Experimental investigation of CTOD fracture toughness in FCAW-GS welds of offshore jacket structure

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Agag Jr This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7196752/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Offshore jackets are essential structures in the energy sector, including wind farms and oil and gas activities. The experiment involves welding a 72 mm K-bevel S355 KT-40 plate utilizing gas-shielded flux-cored arc welding (FCAW-GS) in a horizontal position. Welds are evaluated using microhardness, tensile, Charpy impact toughness at -40°C, crack tip opening displacement (CTOD) at 0°C, and microscopy, subsequently accompanied by statistical analysis and numerical modelling. The highest microhardness is 246 Hv5, meeting the maximum requisite of 325 Hv5, while the yield stress and tensile strength of the welds exceed those of the base metal, measured at 565 and 602 MPa, respectively. The minimum Charpy single value is 73.9 J, and the average value is 108 J, both exceeding the 40 J industry norm. Weld metals (WMs) at the weld centerline and the grain-coarsened heat-affected zones (GCHAZs) have minimal CTOD values of 0.28 mm and 0.36 mm, respectively, surpassing the requisite threshold of 0.15 mm. The microstructure of the GCHAZs has a grain size between 31.8 and 63.5 µm, hence improving corrosion resistance. A one-way ANOVA of the Charpy and microhardness has significant differences corresponding to measurement regions. Mesh and contour plots demonstrate a robust positive correlation among CTOD, load, and displacement. The quadratic equation modelling fracture lengths demonstrates a significant correlation coefficient of 74.7%, producing a parabola with its vertex at x, y (35.435385, 40.2809) mm, which defines optimal crack length. The welds surpass AWS D1.1 criteria, enhancing performance and prolonging structural integrity. Materials Engineering CTOD FCAW fracture toughness mechanical properties microscopy Offshore jacket structure Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 1. Introduction Offshore renewable energy wind farms and oil and gas industries necessitate offshore jacket structures in deep water having high fracture toughness materials such as low carbon steel with suitable strength and impact toughness. The works of Bai and Jin and Sanchez et al. indicate that offshore jacket structures are essential for maintaining the integrity of assets utilized in the offshore renewable energy and oil and gas operations [ 1 ][ 2 ]. These structures are subject to active monitoring by regulatory and national authorities due to the dangers of failure and environmental impacts, as noted by Scherf et al. [ 3 ]. For instance, a significant failure from the occurrence of surface cracks, which have been observed in cyclically loaded structures from the standpoint of fracture mechanics, is indicated in the work by Fajuyigbe and Brennan [ 4 ] and Maljaars et al. [ 5 ]. According to the study of Fondjo and Dzogbewu [ 6 ], the said type of linear defects, such as cracks, can pose a greater risk than rounded defects because of their susceptibility to increasing stress, which needs to be considered in the selection of suitable destructive testing. For instance, more companies are now preventing the failures by testing material properties beyond the normal standards, like using CTOD fracture toughness, instead of correcting the issues after they happen, as pointed out by Kulkarni et al. [ 7 ]. Additionally, Brewer and Sheets [ 8 ] state that the Charpy impact toughness test is not the optimal method for assessing fracture toughness due to its lack of accuracy and indirect relevance. Conversely, the same study indicated that the crack tip opening displacement (CTOD) test, which exceeds traditional material property assessment, is becoming increasingly favoured in the offshore sector, most especially for critical structures and pipelines. The study by Avila et al. advocates for the utilization of CTOD fracture toughness, since it is strongly endorsed for computations in fracture mechanics to assess the severity of material or weld failures and their associated microstructure [ 9 ]. For example, utilizing CTOD is essential for thick-walled materials due to the significant constraint and residual stresses after welding that might result in failures, as demonstrated by Tan et al. [ 7 ]. Consequently, applying CTOD to examine critical welds in structures is essential due to the danger from crack propagation, according to the study of Goli-Oglu and Filatov [ 8 ]. In summary, the potential structural failure due to linear weld defects, which may result in crack propagation, can be alleviated by controlling weld flaws using appropriate welding conditions and employing both non-destructive and destructive testing methods. Utilizing CTOD fracture toughness, substantiated by extensive literature, is of paramount importance. Nonetheless, employing Charpy as a standalone method is inadvisable due to its indirect relevance and insufficient precision in evaluating fracture toughness. The study acknowledges the prior contributions of Coronado and Ceron regarding the CTOD fracture toughness of welds in AISI 1045 medium carbon steel shafting, characterized by a carbon content of 0.45%, welded individually using flux-cored arc welding (FCAW), submerged arc welding (SAW), and shielded metal arc welding (SMAW), serving as the foundational reference [ 9 ]. Furthermore, the investigation by Kitagawa and Kawasaki into the current advancements in high-strength and durable welding consumables for offshore structures serves as a key guideline in selecting the welding process for the project. [ 10 ]. Finally, the research conducted by Setiyanto et al. regarding the application of 1.5% Ni in FCAW to enhance weldability and mechanical properties serves as a significant reference for this work in choosing the welding consumable [ 11 ]. This research constitutes a novel contribution to various fields of science and engineering through the experimental investigation of a K-bevel 72 mm thick plate composed of S355 KT-40 grade, full welding via flux-cored arc welding with gas shielding (FCAW-GS) in a horizontal orientation (2G), employing CTOD fracture toughness testing to evaluate the welds in offshore jacket structures, supplemented by statistical analysis and numerical modelling. This work investigates CTOD fracture toughness in the theoretical design, construction execution, and potential repair maintenance of offshore jacket structures to mitigate crack propagation in welds. Moreover, preselecting welding parameters and performing material testing through appropriate non-destructive testing and suitable destructive testing for the welded experiment are essential for tackling weldability issues and guaranteeing weld integrity, respectively. The primary aim of the study is to avert weld failures resulting from material or weld flaws that may induce crack propagation. This can improve general safety for all inhabitants, maximize asset efficiency, and extend equipment longevity. The succeeding objectives include welding the joint, non-destructive testing using magnetic particles and ultrasonics, and destructive testing using macro-examination, microhardness, tensile, microscopy, CTOD fracture toughness, and Charpy tests. The microscopy at magnifications of 25x and 100x is concentrated on GCHAZ to ascertain the position of fatigue cracks, determine the microstructure phases, and to quantify the corresponding grain sizes in the grain-coarsened heat-affected zone or within 0.5 mm from the fusion line. Moreover, conduct statistical analysis utilizing a one-way ANOVA to investigate the significant differences in crack lengths, Charpy impact values, and microhardness with respect to measurement regions. Additionally, assess and analyze the trend and correlation between load and displacement relative to CTOD through mesh and contour plots. Finally, model the measured crack lengths using numerical fitting and a quadratic equation to define the location of the optimal crack length, an important factor in fracture mechanics. 2. Materials and methods This section delineates the materials and methods in accordance with the established objectives. 2.1. Experimental welding The experiment entails the use of parallel K-bevel joint preparations made from S355 KT-40 material grade, with a thickness of 72 mm, each joint member is measuring 2000 mm in length and 350 mm in width. The junction was welded utilizing complete flux-cored arc welding with gas shielding (FCAW-GS) in a horizontal position. A study indicates that FCAW-GS provides superior weld quality and cleaner welds than self-shielded flux-cored arc welding (FCAW-SS). Both employ flux-cored wire; however, FCAW-GS incorporates an external shielding gas to safeguard the weld against ambient contamination, yielding a smoother finish and reduced spatter [ 12 ]. When CO₂ is utilized in FCAW, it is subjected to the arc's heat, resulting in its decomposition into carbon monoxide and oxygen, so generating energy that amplifies the arc's heat, penetration, and fluidity [ 13 ]. This exothermic reaction, along with the gas's elevated thermal conductivity, results in a deeper and wider weld penetration profile, rendering it appropriate for welding thicker materials [ 13 ]. To check for hydrogen cracking susceptibility, there is a 48-hour delay after welding. Before moving on to destructive testing, non-destructive testing using manual ultrasonics and magnetic particle inspection is carried out to determine the integrity of the welds. 2.1.1. Chemical composition of base material and welding consumable The welding experiment employs S355 KT-40 plate and welding consumables, with their chemical compositions specified in Table 1 and Fig. 1 . The chemical compositions were assessed according to the standard welding criteria specified in AWS D1.1 [ 14 ]. Carbon (C) and manganese (Mn) are definitively the primary elements in both base materials and welding consumables, affecting the carbon equivalent (CE), weldability, and mechanical properties. Moreover, the concentrations of sulphur (S) and phosphorus (P) are controlled due to their potential detrimental impact on weldability, which can cause embrittlement of the weld metal. The high nickel concentration in the filler wire is evident, as nickel atoms in steel interact with carbon to improve toughness, especially at low temperatures, through various methods such as acting as austenite (FCC) stabilizer. The research by Setiyanto et al. indicates that an increase of 1.5% Ni in FCAW diminishes grain boundary ferrite and enhances resistance to cold cracking [ 11 ]. Furthermore, nickel reduces the martensite start (Ms) temperature, improving hardenability and refining the microstructure, which leads to increased yield strength and impact toughness [ 11 ]. Eon et al. assert that nickel especially promotes the formation of a refined martensite structure, distinguished by a higher density of high-angle grain boundaries, which is crucial for toughness [ 15 ]. Table 1 Chemical composition of base metal and filler wire. Element Plate S355 KT-40, 72 mm thick FCAW-GS, 1.2 mm diameter E81T1-K2C C 0.06 0.04 Si 0.19 0.20 Mn 1.49 1.23 P 0.009 0.014 S 0.0015 0.10 Cr 0.13 0.02 Mo 0.01 0.01 Ni 0.37 1.72 V 0.002 0.01 Ti 0.014 0 Cu 0.15 0 Nb 0.028 0 CE 0.37 NA 2.1.2. Welding of joint for CTOD Figure 2 illustrates the simulated weld, including a K-bevel joint preparation executed in a horizontal orientation, whereas Table 2 delineates the welding parameters employed for the joint fabrication. BSEN 1101-2 served as the basis for establishing the minimum preheat based on the welding conditions specified in Table 2 . The minimum preheat, inter-run temperature, and heat input were established accordingly. The full-thickness single-edge notch bend (SENB) samples for the crack tip opening displacement (CTOD) test were covered, considering the notch location, geometry, and orientation were all in accordance with the criteria of ISO 15653 [ 16 ]. The CTOD test specimens were extracted from the weld center and the grain-coarsened heat-affected zone regions (GCHAZs) or within 0.5 from the fusion line. The weld centerline (WCL) is a primary focus of the investigation due to its propensity for crack initiation, attributed to flaws such as slag inclusion, porosity, lack of inter-run fusion, and metallurgical alterations due to dilution [ 17 ]. These defects can function as stress concentrators, making the weld metal more vulnerable to failure. Furthermore, fusion lines between the base metal and the weld or (GCHAZs) are investigated due to historical metallurgical discrepancies, such as the chemical composition of the parent metal and welds between adjacent materials, which might initiate failure [ 18 ]. Conversely, because of the low-carbon steel composition of the base metals and welding consumables, the likelihood of brittle martensite formation leading to hydrogen or heat-affected zone cracking is minimal, resulting in a lower priority for scrutiny [ 19 ]. In summary, this study investigates the relationship between weld metal (WM) and grain-coarsened heat-affected zone (GCHAZ) in connection to CTOD while also performing destructive testing, including tensile, Charpy, and microhardness tests, along with microscope analysis to check the integrity of the welds. Table 2 Welding parameters of offshore jacket structure. Item Parameter Value/Details Base Metal Thickness (mm) 72 Specification S355 KT-40 Carbon Equivalent (CE) 0.37 Yield strength (MPa) 390 Joint Weld joint type K-bevel Bevel Angle 45–50° Weld category Original weld Back gouging Yes Position Welding position 2G (horizontal) Welding Process Process mode Constant Voltage (FCAW-GS) Transfer mode Spray Electrical Characteristics Polarity DCEP Current Root: 190–230 A; Rests: 200–240 A Voltage 21–25 V Heat input (kJ/mm) Root: 0.9–2.3; Rests: 1.0–2.4 Arc efficiency 0.5 Gas Shielding Purely CO₂ Flow rate (L/min) 20–25 Technique Method of back gouging Carbon arc air gouging String or Weaving Both Maximum weaving (mm) 17 Electrode extension (mm) 15–25 Inter-pass cleaning Chipping, grinding, and bopping Temperature Minimum preheat temperature (°C) 110 Maximum inter-run temperature (°C) 243 2.2. Methods of non-destructive testing The welded specimen, made of ferrous material, utilizes AC (alternating current) magnetic particle inspection (MPI) in accordance with ASME V. Alternating current (AC) is favored over direct current (DC) due to its ability to identify surface and slightly subsurface discontinuities, attributed to the "skin effect," which concentrates the magnetic field near the surface, rendering it optimal for detecting surface fractures [ 20 ]. The weld joint is inspected 48 hours post-welding to ensure it is not susceptible to hydrogen cracking prior to non-destructive testing. This delay permits adequate time for hydrogen, which may induce delayed cracking, to diffuse from the weld and perhaps render the cracking observable [ 21 ]. The weld surface and base material are cleansed before inspection to ensure accurate assessment. Required materials comprise the AC magnetic yoke, wet-visible black particles, and white contrast paint. Magnetic particle inspection (MPI) is performed at temperatures not surpassing 50°C, with defect analysis conducted under 500 lux illumination [ 22 ]. White contrast paint is applied to the cleaned and dried surfaces of the base material and weld during inspection. Wet-visible black particles are applied using the AC magnetic yoke angled at 45–60° over the weld or parent material until the entire welded specimen is thoroughly coated [ 22 ]. Defects in welds and materials discovered during testing are recorded and measured using a steel ruler, including the location, length, width, and/or diameter of each flaw. The specimen's thickness is 72 mm, rendering radiography impractical. Iridium-192 necessitates an extended exposure duration to get adequate imaging. A limitation of radiography concerning substantial wall thickness is its challenge in identifying planar defects, including lack of sidewall fusion, fractures, and laminations. Ultrasonic testing is optimal for thick-walled materials and proficient in identifying both planar and volumetric flaws in material. Manual ultrasonic testing (UT) employs A, B, C, and D scans in accordance with ASME V standards [ 20 ]. The A-scan displays three signal echoes: the initial echo on the left signifies the metal surface where the probe is placed; the central echo denotes the defect; and the final echo on the right represents the back wall surface of the material. B, C, and D represent the lateral, superior, and terminal perspectives of the welds, respectively [ 20 ]. The weld and base metal, along with the required surface area of scanning, are thoroughly cleaned before testing to ensure effective scanning and probe connection or coupling efficiency. Finally, significant indications are sketched and recorded and ensure proper evaluation for acceptance or rejection of the inspected weld joint. 2.3. Methods of destructive testing Upon the successful completion of nondestructive testing, destructive mechanical testing is conducted, encompassing tensile testing, macro-examination, microhardness assessment, Charpy impact toughness evaluation, CTOD fracture toughness analysis, and microscopy. Table 3 delineates the scope of destructive testing of welds, while the details are elaborated in the subsequent subsections. According to Table 3 , the test points and notch location for the destructive testing are displayed in the corresponding figures. Table 3 Scope of destructive testing. Destructive testing method Offshore jacket structure Location of test Total specimen Figure Macro-examination Weld with HAZ 1 3 Microhardness 22°C WM, HAZ & BM 1 (68 test points) 4, 13 Tensile at 22°C All-weld longitudinal & transverse 2 ASTM A370 Charpy at -40°C WCL, FL, FL + 2 mm, FL + 5 mm 10 x 3 = 30 14 CTOD at 0°C WCL and GCHAZ (within 0.5mm from FL) 6 6 Microscopy Optical (25x and 100x)—GCHAZ, FL & crack tip, grain size & microstructure 3 x 2 = 6 7–11 2.3.1. Macro-examination and microhardness ISO 17639 is employed to produce specimens intended for macro-examination, assessing weld quality, detecting material defects, and determining the sequence of weld passes. The specimen is magnified by a factor of 10 in compliance with ASTM E340 criteria. Flux-cored arc welding (FCAW) is employed to perform welds that may exhibit defects such as porosity, slag, copper inclusions, and lack of fusion. The total number of runs can be evaluated and measured by a macro-analysis. In addition to macro-examination, a microhardness test is performed to evaluate if the heat-affected zones (HAZs) and weld metal are below the maximum hardness requirement. The aim for microhardness is to attain a lower average value in the weld relative to the heat-affected zone, with all values remaining below 325 Hv5 [ 23 ]. The sample examinations are performed utilizing the macro-specimen. 2.3.2. Tensile testing The welds undergo one all-weld longitudinal and one transverse tensile test in accordance with ASTM A370 to provide confidence prior to CTOD fracture toughness testing [ 24 ]. The principal criteria are tensile strength ( R m ) and yield stress ( Rp 0.2 ), documented to confirm their compliance with the base material and their capacity to withstand load without failure. The R m and Rp 0.2 must reach or surpass the values recommended for ST355 KT-40 base metal’s specification. The applied force and the tension at both extremities of the specimen are quantified and documented. Rp 0.2 represents the greatest stress the weld material can withstand within its elastic limit, whereas R m denotes the ultimate stress prior to failure [ 25 ]. Ultimately, elongation is quantified by the variation in length after the tensile test relative to the original length. 2.3.3. Charpy impact toughness testing at -40°C The Charpy impact toughness test is performed at -40°C in accordance with ASTM A370, with specimens collected from the weld center, fusion line (FL), FL + 2 mm, and FL + 5 mm, which are the suspected regions influenced by welding. The impact toughness of a weld is evaluated by measuring the energy absorbed during fracture under an impact load [ 24 ]. It is utilized to assess the ability of a weld to endure sudden shocks and impacts, hence establishing its appropriateness for application in offshore jacket structures at a minimum design temperature of -40°C. The goal is to achieve a minimum value of 40 J to match the impact toughness of the base metal. 2.3.4. Crack tip opening displacement Fracture propagation in materials can be evaluated using the crack tip opening displacement (CTOD) test with a single-edge notch bend (SENB) specimen, as per ISO 15653 [ 16 ]. This test is appropriate for structures where the principles of Linear Elastic Fracture Mechanics (LEFM) can be employed to evaluate the fracture properties of low-carbon steel weldments, especially when the material exhibits primarily linear elastic behavior and the plastic zone near the crack tip is insignificant relative to the crack length [ 26 ]. The CTOD test evaluates a material's ductility by replicating the propagation of a fatigue fracture, facilitating the assessment of significant flaw size. The CTOD specimen geometry consists of four primary phases [ 27 ]. The test specimen is initially machined and subjected to fatigue or pre-cracking within defined specifications at a temperature of 22°C. The final phase involves fracturing the specimen under controlled conditions at a temperature of 0°C, followed by an analysis of the specimen and the associated data to ascertain the CTOD value. 2.3.4.1. Prefatigued fracture and pre-cracking of CTOD specimen Prefatigued fracture and pre-cracking at ambient temperature are conducted in accordance with ISO 12135 prior to CTOD fracture toughness evaluation [ 28 ]. To facilitate the initiation of a fatigue crack, a machined notch is incorporated into the specimen, owing to the challenges associated with generating a genuine fatigue fracture [ 28 ]. To ensure the accuracy of the CTOD test, the pre-cracking must include the elastic-plastic region. For accurate CTOD fracture toughness testing, the fatigue pre-cracking must be exact within ± 2.5%, and for three-point bend specimens, the maximum fatigue pre-cracking force during the final 1.3 mm or 50% of pre-crack extension must comply with ISO 12135 [ 28 ]. 2.3.4.2. Cracking and measurement of CTOD BS 7448-part 2 is utilized for the assessment and verification of CTOD and its related parameters, including applied force, crack length, displacement, stress intensity factor, and the specimen's width and thickness, as well as tensile, among others. [ 27 ]. The progression of the crack is observed and graphed with load against displacement. The crack tip opening displacement (CTOD) is measured using the clip gauge method, a technique utilized to assess fracture toughness in materials. It utilizes two clip gauges in accordance with ISO 15653, one fixed at the crack mouth opening displacement and the other positioned at the crack tip, to evaluate the crack opening displacement at two distinct points. [ 16 ]. This method optimizes the CTOD measurement process and is widely employed, particularly in weld applications. The objective for CTOD is to achieve a minimum value of 0.15 mm, as stipulated by DNV-OS-C401. [ 29 ]. This value serves as a threshold to guarantee that a material can withstand crack propagation and avert brittle fracture under stress. [ 29 ]. 2.3.4.3. Modes of CTOD fracture The research has employed four modes of fracture [ 30 ]. Initially, M-mode demonstrates a terminal fracture with decreasing stress, with the fracture surface showing indications of tearing. Secondly, U-mode demonstrates a terminal fracture when subjected to increasing stress, with the fracture surface exhibiting ripping [ 30 ]. Thirdly, C-mode demonstrates the ultimate fracture with increasing strain, and the fracture surface shows no signs of ripping [ 30 ]. Finally, a pop-in represents the fourth form of fracture that occurs when the load rebounds to surpass the starting condition after either a load reduction, an increase in displacement, or both [ 30 ]. The aim for fracture mode is to achieve a minimum of U-mode for optimal outcomes. 2.3.5. Microscopy at 25x and 100x Microscopy is performed at 25x magnification to visualize the fatigue crack and at 100x to ascertain the grain size number according to ASTM E112 [ 31 ]. The aim of microscopy is to analyze grain size and determine the microstructure of the GCHAZ, a region strongly suspected of weld failure due to potential grain growth [ 16 ]. Additionally, weld microstructure images are examined in correlation with CTOD values. The expected grain size is between 10 and 100 µm for optimal corrosion resistance [ 32 ], while the microstructure should predominantly consist of ferrite and pearlite, with minimal martensite. 2.4. Statistical Analysis Destructive testing results are analysed using statistical techniques. An advanced one-way ANOVA assesses the significant difference of crack length, Charpy, and microhardness with respect to the measurement locations using a 95% confidence interval by using the p-value and F-critical as the references to either accept or reject the null hypothesis [ 33 ]. Finally, unique mesh and contour plots visualize the relationship, trend, and distortion between CTOD and the load and displacement. 2.5. Numerical modelling A novel approach for ascertaining the average or optimal crack length is presented, utilizing mathematical fitting and the quadratic equation of a parabolic curve as an alternative to traditional methods as described by Eq. 1. The vertex of the parabola determines the optimal crack length, which is a critical parameter in fracture mechanics to ascertain the integrity of materials, such as the ratio of average crack length to width ratio ( a o /W ) [ 16 ]. 3. Results and discussion 3.1. Results of actual welding experiment The study aims to conduct the welding experiment in compliance with design codes and standards, incorporating a detailed welding procedure specification to obtain a tough weld. The heat input was maintained within the specified range, as it is a crucial welding parameter for regulating the toughness of the weld [ 34 ], which is affected by the weldability of the base materials, including their thickness and carbon equivalent [ 35 ]. Moreover, the impact of alloying elements was controlled, especially the carbon concentration, which can alter the Ac 3 (transformation of ferrite to austenite), Ac 1 (initiation of austenite formation), and M s (formation of martensite) [ 36 ][ 37 ]. The utilization of low carbon inhibits a high proportion of martensite, thus diminishing hardness and vulnerability to hydrogen and heat-affected zone cracking while enhancing ductility [ 38 ][ 39 ]. Furthermore, enhanced weldability and mechanical properties are achieved by keeping low levels of sulfur and phosphorus [ 40 ][ 41 ]. The chemical composition of base metal and welding consumables was meticulously controlled to provide optimal cooling rates and yield good mechanical properties of the welds [ 42 ]. In summary, the weld's microstructures mostly comprise ferrite and pearlite, leading to improved ductility and fracture toughness. The evidence comprises microscopy images, Charpy impact toughness, and CTOD data, which are discussed in the following sections. In conclusion, superior welds are achieved by the judicious selection of compatible base metals and welding consumables, optimal welding settings, skilled welders, effective supervision, and the use of suitable welding tools, equipment, and instruments. 3.2. Results of non-destructive testing Magnetic particle testing is a visual aid method employed to detect surface and near-surface flaws of the welds and adjacent base metal [ 20 ]. Moreover, ultrasonics is a precise technique utilized for identifying both internal and external material defects, with accuracy up to 10 microns. The test results documented random volumetric indications in three locations near the root, with a maximum dimension of 1.5 mm, which are deemed acceptable per AWS D1.1 standards [ 14 ]. In conclusion, the non-destructive tests conform to AWS D1.1 requirements, signifying that the welds are suitable for destructive testing. 3.3. Results of destructive testing After the non-destructive inspection, the welded joint was subjected to destructive testing, encompassing macro-examination, microhardness assessment, tensile testing, CTOD fracture toughness evaluation, and microscopy analysis, as detailed in the following subsections. 3.3.1. Macro-examination and microhardness A macro-examination was conducted to confirm the acceptability of the weld before proceeding to other destructive testing methods. Figure 3 illustrates that the weld contains a minor flaw of 1 mm slag inclusion at the root, which is permissible according to AWS D1.1 [ 14 ]. An acceptable weld is attained by the regulation of welding factors, consumables, base metal, and the proficiency of the welder. Welds with minimal discontinuities significantly enhance mechanical properties, including tensile strength and toughness, while welds with substantial defects create additional voids, compromising metallic bonding and leading to reduced tensile strength and toughness [ 43 ]. Moreover, Fig. 4 depicts the microhardness graphs for the left and right sides of the weld joint derived from the macro specimen. The hardness of the central region with root and other weld regions are assessed using one-way ANOVA. The disparity in weld values is not an issue; nonetheless, it is crucial that microhardness values remain below 325 Hv5 according to EEMUA 158 [ 23 ]. The microhardness illustrated in Figs. 4 and 13 indicates that the heat-affected zones exhibit greater hardness than the weld metal. The discovery aligns with the research of Celin and Burja, demonstrating that the heat-affected zone cools more rapidly than the weld center, leading to the development of hard martensitic products with increased hardness [ 44 ]. Furthermore, lower microhardness values at the weld center result from tempering, which enhances ductility and hardness [ 45 ]. In summary, the macro-examination photos showed that the welds are accepted and have no significant defects, and the micro-hardness results meet EEMUA requirements, providing confidence that the welds are suitable for Charpy and CTOD tests. 3.3.2. Tensile testing Table 6 presents the results of the tensile testing conducted at room temperature. The recorded values of yield stress and tensile strength are above the base metal’s specified tensile properties. The all-weld longitudinal test is conducted just on weld metal or parallel to the weld length concerning the CTOD specimen, whereas the transverse tensile specimen is extracted across the weld metal and heat-affected zone for the CTOD of GCHAZ specimen. Yield stress data are required as an input parameter in CTOD, which is calibrated to correspond with the CTOD test temperature at 0°C. These tensile specimens are utilized to assess the properties of weld metal, including tensile strength, ductility, and hardness, including defects and unusual inclusions. The rationale is that longitudinal tensile specimens typically demonstrate superior strength and toughness compared to transverse specimens, owing to the alignment of the material's grain structure with the applied force in the longitudinal direction [ 46 ]. On the other hand, transverse specimens experience force perpendicular to the grain direction, rendering them more vulnerable to fracture along the weaker grain boundaries [ 46 ]. In summary, tensile testing accurately assesses the properties of the weld and heat-affected zone before CTOD testing, which are enhanced by the base metal and welding consumable compositions, welding parameters, and the absence of significant defects in the welds. 3.3.3. Charpy impact toughness at -40°C Before CTOD testing, Charpy impact toughness is assessed at the weld metal, fusion line (FL), fusion line plus 2 mm (FL + 2 mm), and fusion line plus 5 mm (FL + 5 mm), which are anticipated areas of metallurgical change affected by welding. The outcomes are presented in Table 8 and illustrated in Fig. 13 . All recorded values exceed the threshold of 40 J for both individual and average measurements. The satisfactory attainment of Charpy impact toughness is realized by the judicious selection of the chemical composition of the base metal and welding consumables, encompassing filler wire and appropriate shielding gas to control the microstructure [ 47 ]. Furthermore, selecting welding consumables such as nickel contents and other alloying elements, utilizing multi-pass welding for tempering the previous bead welds, and managing the heat input within the designated range are advantageous for regulating grain size [ 48 ]. In conclusion, the Charpy impact toughness test has been successfully conducted, instilling confidence in the execution of the CTOD test. One-way ANOVA is utilized to conduct thorough Charpy impact toughness analyses of the substantial variations in measurement regions, as outlined in section 3.4.1 . 3.3.4. Crack Tip Opening Displacement (CTOD) The objective of the CTOD fracture toughness test is to assess the welds' resistance to crack propagation, utilizing the applicable pre-cracking and cracking parameters outlined in Table 4 and Table 5 . Figure 5 illustrates the measurement of crack length utilizing Eq. 1 to compute the average crack length. The six specimens, as shown in Fig. 6 , depicted the fracture surfaces taken from the weld center and grain-coarsened heat-affected zones (GCHAZs). Underneath each specimen is the corresponding load vs. extension curve, which categorizes the corresponding mode of fracture. Table 9 indicates the sizes of the average crack length ( a o ), which was used to calculate the value of a o /W , where W is the width of the specimen. Equation 1. \(\:{a}_{0}=\frac{1}{8}({a}_{2}+\:{a}_{3}+{a}_{4}+{a}_{5}+{a}_{6}+{a}_{7}+{a}_{8}+\frac{{a}_{1}+{a}_{9}}{2})\:\) [28] Referring to Table 6 , the WM-2 specimen had the lowest CTOD of 0.28 mm, while the highest was GCHAZ-1 at 2.38 mm, both having ductile crack propagation (U-mode). Table 6 shows that there is a total of four with U-mode, which are acceptable. The ultimate goal for a weld is to have the perfect M-mode for a stable ductile failure [ 49 ], which is obtained in two specimens, GCHAZ-2 and WM-3. Moreover, according to the study of Zhu et al., a material with high fracture toughness yields ductile fracture, whereas a material with low fracture toughness is susceptible to brittle fracture [ 50 ]. In conclusion, the welds exhibit satisfactory performance, as all failures are M and U modes with CTOD values above 0.15 mm. Furthermore, welds demonstrate improved CTOD results through the utilization of low carbon, 1.7% nickel in welding consumables, and diminished residual stresses attained through suitable preheating and controlled heat input via multi-pass welding, narrow bead width, and chipping methods that yield enhanced mechanical properties [ 51 ]. Table 6 describes the categorical variables with the corresponding test results of continuous variables. The location of the notch, geometry, orientation, and fracture mode are the categorical variables considered in accordance with ISO 15653 [ 16 ]. Table 6 delineates the notch location for six specimens. These are taken from the weld metal (WM) and grain-coarsened heat-affected zone (GCHAZ) areas, or within 0.5 mm of the fusion line, exhibiting B x B (square geometry) and NP orientation. B represents the thickness of the specimen, whereas NP refers to a specimen exhibiting through-thickness properties. Furthermore, Table 6 illustrates that the minimum and maximum values of the CTOD for both WM and GCHAZ specimens exhibit a significant positive correlation with displacement ( Vp ), as displacement directly quantifies CTOD in a three-point bending test. This corresponds with the findings of Khor et al., which indicate that the CTOD test measures the opening displacement at the crack tip, with displacement functioning as the plastic component of the clip gauge opening [ 52 ]. Lastly, mesh and contour plots were used to plot the relationship of CTOD with load and displacement in Section 3.4.2 . In summary, the distinct number of specimens utilized for CTOD testing precisely characterized the fracture toughness properties of the weld metal and grain-coarsened heat-affected zone. The fracture toughness of CTOD is improved by controlled welding parameters and standard testing conditions. Table 4 Pre-cracking and cracking parameters. Pre-cracking and cracking parameters Loading Span (mm) B (mm) a 0 /W Pre-cracking temperature (°C) Cracking temperature (°C) 288 72 0.56 22 0 Table 5 Tensile and pre-cracking parameters. Tensile and pre-cracking GCHAZ and WM at 22°C Tensile (N/mm²) Stress intensity factor (N/mm³/²) Pre-cracking force (kN) Rp 0.2 (BM) R m (BM) Rp 0.2 (Weld) R m (Weld) Rp 0.2 (HAZ) R m (HAZ) kF (Weld) kF (HAZ) Ff (Weld) Ff (HAZ) 385 471 565 602 475 537 1584 1358 77 66 N/mm 3/2 Loading rate mm/min kF (weld) kF HAZ WM HAZ 3956 4464 0.38 0.42 Table 6 CTOD results. Location Location of notch Geometry* Orientation* Rp 0.2 (Note 1) Load (kN) Vp (mm) CTOD (mm) Fracture mode Grain size (µm) GCHAZ1 FL < 0.5 mm B x B NP 490 216.79 9.64 2.38 U 31.8, 44.9 GCHAZ2 FL < 0.5 mm B x B NP 490 205.26 3.14 0.84 M 31.8, 63.5 GCHAZ3 FL < 0.5 mm B x B NP 490 173.70 1.19 0.36 U 44.9 WM1 WCL B x B NP 580 191.26 2.26 0.61 U - WM2 WCL B x B NP 580 183.01 0.89 0.28 U - WM3 WCL B x B NP 580 194.54 1.66 0.47 M - Notes: 1. Rp 0.2 is reported as yield stress and corrected to the CTOD test temperature, 0°C. 2. Young's modulus of elasticity = 207000 N/mm² and Poisson's ratio = 0.3. * Please refer to ISO 15653 Annex A. 3.3.5. Microscopy The microscopic examination concentrated on the grain-coarsened heat-affected zone (GCHAZ) within 0.5 mm of the fusion line, as previously noted, due to the anticipated onset of failure resulting from metallurgical alterations. Figures 7 to 12 display microscope images of the GCHAZs of the fractured specimen depicted in Fig. 6 , including samples with the associated CTOD values in Table 6 . The welds demonstrate that BCC pearlite and ferrite are the primary constituents, resulting in improved ductility. Pearlite consists of alternating layers of ferrite (α-iron) and cementite (Fe₃C), appearing as small, lath-like structures within the ferrite matrix [ 53 ]. Furthermore, due to the ferrous nature of the microstructural phases, they demonstrate a ductile-to-brittle transition with respect to temperature, hence affecting the material's toughness [ 54 ]. Figure 7 , Fig. 9 , and Fig. 11 depict the locations of fatigue fractures and the corresponding GCHAZ regions, while Fig. 8 , Fig. 10 , and Fig. 12 provide the relevant grain size numbers of the GCHAZs according to ASTM E112, which are 6–7, 5–7, and 6, respectively [ 31 ]. According to ASTM E112 Table 4 , grain size numbers 7, 6, and 5 equate to 31.8, 44.9, and 63.5 µm, respectively [ 31 ]. The measured grain size values fall within the corrosion resistance range for low carbon steel, which is 10 to 100 µm [ 32 ]. Consequently, correlating grain size with the acquired CTOD values of GCHAZs will prove to be difficult. The research by Cathapuram and Lagad indicates that CTOD fracture toughness is not exclusively dependent on grain size, since a decrease in grain size of ferrous materials will increase hardness and may trigger a ductile-to-brittle transition [ 55 ]. Additional factors influencing fracture toughness include base metal thickness, welding carbon and nickel contents, other alloying elements, and welding parameters. The conclusion is consistent with the studies conducted by Inoue et al. [ 56 ] and Hanamura et al. [ 57 ], suggesting that reduced grain sizes and additional improvement techniques can increase toughness, hence improving CTOD. In summary, the ferrite and pearlite microstructural phases of the GCHAZs exhibit ductility, and the grain sizes of the said region are suitable for corrosion resistance. These indicate that the examined weld region possesses optimal mechanical properties, including tensile strength, impact resistance, and fracture toughness. 3.4. Statistical analysis 3.4.1. One-way ANOVA The investigation progresses by employing one-way ANOVA box plots to analyze the significant differences in microhardness, Charpy impact toughness, and fracture lengths about their measurement locations at a 95% confidence interval. Table 7 and Table 8 , along with Fig. 13 and Fig. 14 , demonstrate that the F-statistic values are significantly lower than the F-critical values, while the p-values are below 0.05, indicating a highly significant difference in the means of microhardness and Charpy impact toughness relative to their measurement locations. The minor inconsistencies in welds produced by semi-automatic welding processes, such as FCAW-GS, may elucidate the differences compared to those generated by fully automated methods. The variation in welding effects over different areas of a weld joint can lead to non-homogenous material properties within the weld regions [ 48 ]. This finding is consistent with ISO 15653, which justifies the requirement for CTOD fracture toughness across all variations [ 16 ]. Figure 13 illustrates that the heat-affected zones (HAZs) region has the highest mean microhardness as compared to the weld metal (WM) region. WM has better mechanical properties since the fusion zone lacks an additional weld that would temper the region [ 48 ]. Furthermore, the cooling period of the HAZ is more rapid than that of the weld, resulting in smaller grains and some martensite microstructure, which yield higher microhardness values compared to the weld [ 48 ]. Conversely, referring to Fig. 14 , the Charpy impact toughness of the fusion line plus 5 mm (FL + 5) exhibits the highest mean, as the base metal region remains largely unaffected by metallurgical alterations during welding, whereas the weld metal demonstrates the lowest toughness due to significant impacts from the welding process, resulting in non-uniform material properties of the weld region [ 48 ]. Nevertheless, certain sections of the fusion lines (FL and FL + 2) exhibit impact toughness inferior to that of the weld metal (WM) due to insufficient tempering. [ 58 ]. Xiao et al. assert that tempering enhances mechanical properties, including ductility and toughness [ 59 ]. Finally, Fig. 15 illustrates outliers of diminished values for the measure of crack lengths; the average measurements obtained from the crack edge may be inferior to those at the center due to the fracture's geometry and the applied stress [ 60 ]. Figure 15 indicates that the mean crack lengths from the measurement zones exhibit no significant difference, as the F-statistic exceeds the F-critical value and the P-value is more than 0.05, attributable to the use of standard, precise input variables and fracture toughness properties of the material. In summary, employing advanced one-way ANOVA successfully analyzes the significant differences of critical variables concerning their measurement locations. Microhardness and Charpy impact toughness exhibit substantial variations based on their measurement locations, caused by metallurgical alterations, whereas average crack lengths from 6 groups show no significant differences. Table 7 Microhardness measurements and one-way ANOVA analysis. BM (Hv5) WM (Hv5) HAZ (Hv5) 194 212 175 204 217 201 218 181 234 219 152 198 202 197 240 153 201 209 193 223 165 197 207 203 202 157 197 222 207 201 169 206 228 220 187 154 207 213 191 212 203 211 228 182 206 207 214 178 211 213 211 197 206 205 199 216 215 185 213 202 177 227 216 201 246 225 216 227 Summary Groups Count Sum Average Variance BM 12 2171 180.9167 593.9015 WM 16 3330 208.125 66.25 HAZ 40 8304 207.6 308.759 ANOVA Source of Variation SS df MS F-statistic P-value F-critical Between Groups 7118.718627 2 3559.359 11.82314 4.18E-05 3.138142 Within Groups 19568.26667 65 301.0503 Total 26686.98529 67 Table 8 Charpy impact toughness measurements and one-way ANOVA analysis. FL (J) FL + 2 mm (J) FL + 5 mm (J) WM (J) 246.5 83.5 > 300 124.1 112 73.9 > 300 103 133 112.8 > 300 97.2 145.8 300 > 300 172.7 171.7 52.9 > 300 177.2 160.4 258.6 > 300 180.7 > 300 197.4 184.8 191 > 300 204.3 Summary Groups Count Sum Average Variance FL 6 1800 300 0 FL + 2 mm 9 1666.5 185.1667 11300.06 FL + 5 mm 12 2232.4 186.0333 4124.704 WM 6 969.4 161.5667 2167.843 ANOVA Source of Variation SS df MS F-statistic P-value F-critical Between Groups 73042.4297 3 24347.48 4.815974 0.007676 2.93403 Within Groups 146611.42 29 5055.566 Total 219653.8497 32 Table 9 Crack length measurements and one-way ANOVA analysis. Crack length GCHAZ-1 (mm) GCHAZ-2 (mm) GCHAZ-3 (mm) WM-1 (mm) WM-2 (mm) WM-3 (mm) a 2 39.43 38.97 39.34 39.28 38.73 38.97 a 3 39.95 39.61 40.26 40.04 39.87 39.83 a 4 40.08 39.09 40.87 40.37 40.41 40.21 a 5 39.88 38.77 40.38 40.17 40.26 40.05 a 6 40.16 40 40.38 40.3 40.45 40 a 7 39.91 39.6 40.44 39.88 40.12 39.24 a 8 39.35 39.11 39.83 38.95 39.24 38.65 (a 1 + a 9 ) 2 38.155 37.44 38.2065 38.265 37.975 37.605 Ave ( a 0 ) 39.61438 39.07375 39.96331 39.65688 39.63188 39.31938 Summary Groups Count Sum Average Variance GCHAZ-1 8 316.915 39.61438 0.431253 GCHAZ-2 8 312.59 39.07375 0.599455 GCHAZ-3 8 319.7065 39.96331 0.711039 WM-1 8 317.255 39.65688 0.565864 WM-2 8 317.055 39.63188 0.810928 WM-3 8 314.555 39.31938 0.795217 ANOVA Source of Variation SS df MS F-statistic P-value F-critical Between Groups 3.782613 5 0.756523 1.15979 0.344824 2.437693 Within Groups 27.3963 42 0.652293 Total 31.17891 47 3.4.2. Mesh and contour plots Figure 16 shows mesh and contour plots, which are employed to depict the interrelationship among three variables, emphasizing a unique facet of this study. The CTOD demonstrates a strong correlation with load and displacement, as it directly measures the crack's opening behaviour at the tip under applied force, which is naturally influenced by the load and resultant material deformation [ 60 ]. Figure 16 also shows slight distortion observed near the midway of the load at low displacement levels. When a load is applied to a fractured component, the material deforms, leading to the advancement of the crack. The quantity of the load immediately affects the extent of deformation and, consequently, the CTOD [ 50 ]. An augmented load generally results in a larger crack opening and an increased CTOD value, which conclude both toughness and ductility of the material. In conclusion, the generated unique mesh and contour plots accurately depict the relationship between the interaction of welds’ CTOD with load and displacement. 3.5. Modelling with quadratic equation An additional innovation of the investigation is the utilization of numerical modelling with a quadratic equation, as delineated in Eq. 2. The objective is to ascertain the horizontal (x) position of the optimal crack length to model across all specimen data. The documented crack lengths from Table 9 are graphically represented alongside the quadratic fitting line, as depicted in Fig. 17 . The correlation coefficient (R²) of 74.7% derived from the fitting of Eq. 3 signifies a strong link, identifying a root on the x-axis of 3.937265 (unitless) or 35.435385 mm from a 72 mm specimen thickness ( B ), which denotes the position of the optimal crack length resulting in a y-value of 40.2809 mm. This method is equally beneficial for individual specimens by analyzing their data and calculating the quadratic equation to ascertain the optimal crack length of a specimen. Equation 2. \(\:y={ax}^{2}+bx+c\) {Quadratic formula} Equation 3. \(\:y={-0.1323x}^{2}+1.0418x+38.23\) {Modelled quadratic equation} The application of average crack length is essential for calculating CTOD and for assessing the ratio of average crack length to specimen width ( a₀/W ), where W is the specimen width, a vital parameter in fracture mechanics that indicates the depth of a crack relative to its width [ 22 ]. The conventional calculation method results in a final average of a 0 /W as 0.55, but our method generates 0.56, indicating a minimal discrepancy. The results reside within the designated range of 0.45 to 0.70 as stipulated by E1290-02 [ 61 ]. This ratio is essential as it directly influences the structural integrity of a material, particularly in evaluating the risk of failure under stress; a larger ratio signifies a heightened likelihood of fracture due to increased stress concentration at the crack tip [ 61 ]. In summary, plotting the measured fracture lengths of a specimen and applying a quadratic fit produces a parabolic curve, representing a unique approach or an alternative to conventional methods, as illustrated in Eq. 1. The vertex of the parabola identifies the optimal crack length, corresponding to the mean crack length ( a 0 ), a crucial parameter in fracture mechanics. 4. Conclusion and Future Work The study examines FCAW-GS welds with a K-bevel joint design, concentrating on CTOD fracture toughness testing of the weld center and GCHAZ to mitigate failure of offshore jacket structures caused by crack propagation. The microhardness of the welds on both sides of the weld joint has a similar profile, reflecting a uniform influence of welding and cooling, with a favorable peak value of 246 Hv5, which satisfies the EEMUA 158 maximum requirement of 325 Hv5. All weld and HAZ regions exhibit exceptional impact toughness, with a minimum Charpy single value of 73.9 J and an average value of 108 J, both above the 40 J industry standard. The CTOD of CGHAZ and the weld center, with values of 0.36 mm and 0.28 mm, respectively, surpass the stipulated 0.15 mm threshold outlined in DNV-OS-C401. The microstructures of the GCHAZs have no signs of grain growth and yield a grain size ranging from 31.8 to 63.5 µm, indicating enhanced corrosion resistance. The tensile strength surpasses that of the base metal, with yield and ultimate tensile strength values of 565 MPa and 602 MPa, respectively. The welds adhere to industry standards, as the mechanical properties, including yield and tensile strength, microhardness, Charpy impact toughness, and CTOD fracture toughness, have achieved the requisite values, hence ensuring integrity and safety. Statistical examination utilizing one-way ANOVA, with box plots and tables, reveals no significant variation in crack lengths among groups of specimens; nonetheless, Charpy impact toughness and microhardness demonstrate substantial variances contingent upon their respective measurement locations. Furthermore, the mesh plot and contour map validate the robust association between CTOD, load, and displacement. Finally, the optimal crack length is ascertained using numerical modelling of the documented crack lengths utilizing a quadratic equation, with a yield ratio of average crack length to width of 0.56, falling within the industry standard range of 0.45 to 0.7. The findings have considerable application for both industry and academia, especially in various fields of engineering, particularly in the front-end and detailed designs, construction, installation, and maintenance of offshore jacket structures and analogous infrastructure. The CTOD tests concentrate on the GCHAZ and weld center regions, facilitating further research on the heat-affected zones or beyond the fusion lines. Finally, the data and conclusions can be utilized in future studies to enhance the assessment of fracture mechanics, hence improving the understanding of stresses and acceptance criteria for weld defects in low-carbon steel structures. Abbreviations Nomenclature and acronyms # Symbol/Acronym Description Unit 1 AC Alternating Current - 2 A c1 Start formation of austenite o C 3 A c3 Transformation of ferrite into austenite o C 4 a 0 average crack length, mm mm 5 ANOVA Analysis of Variance - 6 ASME American Society of Mechanical Engineers - 7 ASTM American Society for Testing and Materials - 8 AWS American Welding Society - 9 B specimen thickness mm 10 BCC Body-Centred Cubic - 11 CE Carbon Equivalent % 12 CTOD Crack Tip Opening Displacement mm 13 EEMUA Engineering Equipment and Materials Users Association - 14 FCAW-GS Flux-Cored Arc Welding Gas-Shielded - 15 FCC Face-Centered Cubic - 16 Fe 3 C Cementite - 17 Ff Pre-cracking force - 18 FL Fusion Line - 19 GCHAZ Grain-Coarsened Heat Affected Zone - 20 HSLA High strength low alloy - 21 HAZ Heat affected zone - 22 J Joules - 23 Kf Stress intensity factor - 24 LEFM Linear Elastic Fracture Mechanics - 25 MPI Magnetic Particle Inspection - 26 M s Start formation of martensite o C 27 N Normal to welding direction - 28 P Parallel to welding direction - 29 PAUT Phased Array Ultrasonic Testing - 30 Q Weld thickness direction - 31 Rm Ultimate Tensile Strength (UTS) MPa 32 Rp 0.2 Yield Strength (YS) MPa 33 SAW Submerged Arc Welding - 34 SENB S ingle-edge notched bend - 35 SMAW Shielded Metal Arc Welding - 36 W specimen width mm 37 WCL Weld centreline - 38 δ CTOD - Crack Tip Opening Displacement mm 39 µm microns µm 40 Vp displacement mm Declarations Data Availability Statement The data for this study are provide and accessible in the tables, pictures, plots, and figures. 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Cathapuram S and Lagad V (2019) Factors affecting impact toughness in carbon steels. NACE - International Corrosion Conference Series, 2019, vol. 2019-March. March 24-28, 2019, Teneesee, USA. Inoue T, Qiu H, Ueji R, and Kimura Y (2021) Ductile-to-brittle transition and brittle fracture stress of ultrafine-grained low-carbon steel. Materials (Basel)., vol. 14, no. 7, 2021, doi: 10.3390/ma14071634. Hanamura T, Yin F, and Nagai K (2004) Ductile-brittle transition temperature of ultrafine ferrite/cementite microstructure in a low carbon steel controlled by effective grain size. ISIJ Int., vol. 44, no. 3. doi: 10.2355/isijinternational.44.610. Alfredsson B, Hazar S, and Lai J (2021) Loading rate and temperature effects on the fracture toughness of a high strength bearing steel. Eng. Fract. Mech., vol. 245. doi: 10.1016/j.engfracmech.2021.107600. Xiao Y, Li W, Zhao HS, Lu WX, and Jin XJ (2016) Investigation of carbon segregation during low temperature tempering in a medium carbon steel. Mater. Charact., vol. 117. doi: 10.1016/j.matchar.2016.04.021. Ritchie RO and Liu D (2021) Introduction to Fracture Mechanics, 1st Edition - June 23, 2021, Elsevier, Paperback ISBN: 9780323898225, eBook ISBN: 9780323902793. doi: 10.1016/C2020-0-03038-0. Tagawa T et al. (2010) Difference between ASTM E1290 and BS 7448 CTOD estimation procedures. Weld. World, vol. 54, no. 7–8, 2010, doi: 10.1007/BF03263504. Additional Declarations The authors declare no competing interests. Supplementary Files Nomenclature.docx Nomenclature and Acronyms GraphicalAbstract.jpg Graphical Abstract Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7196752","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":489779730,"identity":"c4c0619d-fa13-48d4-b53d-fd9b81a38d72","order_by":0,"name":"Gil M. Agag Jr","email":"data:image/png;base64,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","orcid":"https://orcid.org/0009-0006-9680-9614","institution":"Mapua University","correspondingAuthor":true,"prefix":"","firstName":"Gil","middleName":"M.","lastName":"Agag","suffix":"Jr"}],"badges":[],"createdAt":"2025-07-23 13:11:34","currentVersionCode":1,"declarations":{"humanSubjects":false,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":false,"humanSubjectConsent":false,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-7196752/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7196752/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":87473910,"identity":"c46daeec-ed39-42bf-bc4e-e890caed3997","added_by":"auto","created_at":"2025-07-24 08:52:43","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":159879,"visible":true,"origin":"","legend":"\u003cp\u003eChemical composition of plate and filler wire.\u003c/p\u003e","description":"","filename":"image1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/04c83e35e56a0d75c0dc4abc.jpeg"},{"id":87474896,"identity":"43802da8-fc3e-4620-ac15-992bef371bfe","added_by":"auto","created_at":"2025-07-24 09:00:44","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":204383,"visible":true,"origin":"","legend":"\u003cp\u003eK-bevel simulated welds at 2G position.\u003c/p\u003e","description":"","filename":"image2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/f806d934ad1fab282c97dd2a.jpeg"},{"id":87473914,"identity":"423983f5-be4a-475d-98bd-7949d93dc441","added_by":"auto","created_at":"2025-07-24 08:52:44","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":679789,"visible":true,"origin":"","legend":"\u003cp\u003eMacro examination with target CTOD observation area.\u003c/p\u003e","description":"","filename":"image3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/2148c0e849f75db55fdd9f44.jpeg"},{"id":87474894,"identity":"fad6e2e9-9968-40ad-9f44-8fa0942d9216","added_by":"auto","created_at":"2025-07-24 09:00:44","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":299977,"visible":true,"origin":"","legend":"\u003cp\u003eMicrohardness history at left and right sides of weld.\u003c/p\u003e","description":"","filename":"image4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/0a58a5d3bad9ccbf15ebf97d.jpeg"},{"id":87474898,"identity":"d04e6154-ef46-41cd-aed5-2d14cced7c7f","added_by":"auto","created_at":"2025-07-24 09:00:44","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":110896,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurements of crack length.\u003c/p\u003e","description":"","filename":"image5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/ab95e5ca9fced458b7154171.jpeg"},{"id":87475836,"identity":"d2da6996-eefb-40e5-9a78-5578ff7faa48","added_by":"auto","created_at":"2025-07-24 09:08:44","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":741786,"visible":true,"origin":"","legend":"\u003cp\u003eFracture surfaces with load vs. extension curve.\u003c/p\u003e","description":"","filename":"image6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/39a4dd6835802c9f0976f72e.jpg"},{"id":87473920,"identity":"fbdab01e-014c-47cc-bd9f-a3664ea8ae84","added_by":"auto","created_at":"2025-07-24 08:52:44","extension":"jpeg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":767263,"visible":true,"origin":"","legend":"\u003cp\u003eMicroscopy 25x and 100x of fatigue crack at GCHAZ-1.\u003c/p\u003e","description":"","filename":"image7.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/726fa39db0a76f18ee2ae696.jpeg"},{"id":87473939,"identity":"860c60b9-e47b-451b-833a-77306d67572b","added_by":"auto","created_at":"2025-07-24 08:52:44","extension":"jpeg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":750566,"visible":true,"origin":"","legend":"\u003cp\u003eGrain size number 6–7 at GCHAZ-1.\u003c/p\u003e","description":"","filename":"image8.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/318b54bcd260144db6725678.jpeg"},{"id":87473919,"identity":"7f042865-41c5-4bf9-960d-b939e5ec6646","added_by":"auto","created_at":"2025-07-24 08:52:44","extension":"jpeg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":810640,"visible":true,"origin":"","legend":"\u003cp\u003eMicroscopy at 25x and 100x of fatigue crack at GCHAZ-2.\u003c/p\u003e","description":"","filename":"image9.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/498640e1b00016588b85510f.jpeg"},{"id":87476850,"identity":"e05e381c-e95a-4821-aea9-3f6ac33493c7","added_by":"auto","created_at":"2025-07-24 09:16:44","extension":"jpeg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":756846,"visible":true,"origin":"","legend":"\u003cp\u003eGrain size number 5–7 at GCHAZ-2.\u003c/p\u003e","description":"","filename":"image10.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/8acff9bc065a73e8a037254e.jpeg"},{"id":87473925,"identity":"cca125b1-981c-4451-9a75-7bd7bd55264a","added_by":"auto","created_at":"2025-07-24 08:52:44","extension":"jpeg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":805333,"visible":true,"origin":"","legend":"\u003cp\u003eMicroscopy 25x and 100x of fatigue crack at GCHAZ-3.\u003c/p\u003e","description":"","filename":"image11.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/786046888604f5c02c02daac.jpeg"},{"id":87475843,"identity":"4ecf8e8f-9c08-4f1a-a187-35b7e067c60e","added_by":"auto","created_at":"2025-07-24 09:08:44","extension":"jpeg","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":778026,"visible":true,"origin":"","legend":"\u003cp\u003eGrain size number 6 at GCHAZ-3.\u003c/p\u003e","description":"","filename":"image12.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/693470edcc124091dc9461e4.jpeg"},{"id":87474900,"identity":"8258e248-a308-42f5-8783-d8b19f78a2ea","added_by":"auto","created_at":"2025-07-24 09:00:44","extension":"jpeg","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":277690,"visible":true,"origin":"","legend":"\u003cp\u003eOne-way ANOVA Boxplot of Microhardness.\u003c/p\u003e","description":"","filename":"image13.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/3868b16b3f5ec0014183d5ca.jpeg"},{"id":87473935,"identity":"89640258-dd3c-4fc5-88ac-c2e73e8c62c4","added_by":"auto","created_at":"2025-07-24 08:52:44","extension":"jpeg","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":225503,"visible":true,"origin":"","legend":"\u003cp\u003eOne-way ANOVA Boxplot of Charpy Impact Toughness.\u003c/p\u003e","description":"","filename":"image14.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/4c67deca6f35bcfd03a891aa.jpeg"},{"id":87475848,"identity":"a3fbbb15-9c75-40d9-9624-285351dbb8fd","added_by":"auto","created_at":"2025-07-24 09:08:44","extension":"jpg","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":28036,"visible":true,"origin":"","legend":"\u003cp\u003eOne-way ANOVA box plot of crack lengths.\u003c/p\u003e","description":"","filename":"image15.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/006d53e38c748974ba263a67.jpg"},{"id":87473940,"identity":"e216633e-1f24-4ecd-a6fc-0696ac004c4a","added_by":"auto","created_at":"2025-07-24 08:52:44","extension":"jpeg","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":225558,"visible":true,"origin":"","legend":"\u003cp\u003eCTOD load \u0026amp; displacement.\u003c/p\u003e","description":"","filename":"image16.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/70888c0d799aad85378d8b7e.jpeg"},{"id":87473947,"identity":"078fd446-bbbd-4aef-9d7b-dccdb409e9c5","added_by":"auto","created_at":"2025-07-24 08:52:44","extension":"jpg","order_by":17,"title":"Figure 17","display":"","copyAsset":false,"role":"figure","size":45537,"visible":true,"origin":"","legend":"\u003cp\u003ePlots and fit of crack lengths.\u003c/p\u003e","description":"","filename":"image17.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/207c997f262fe94cf4747cdb.jpg"},{"id":88505062,"identity":"2f283e26-c087-4ad7-ac4f-151a6f65adf5","added_by":"auto","created_at":"2025-08-07 07:14:46","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":9391113,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/8734abc2-9aa6-40d0-adca-78c6a4bdd1f0.pdf"},{"id":87474895,"identity":"449e8949-fd0e-4268-b75a-cb474f450cbd","added_by":"auto","created_at":"2025-07-24 09:00:44","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":27916,"visible":true,"origin":"","legend":"\u003cp\u003eNomenclature and Acronyms\u003c/p\u003e","description":"","filename":"Nomenclature.docx","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/ead4754b81d3f5d736da14cd.docx"},{"id":87473912,"identity":"6a7c2a04-5b35-4e3c-b499-4cd07b8d4598","added_by":"auto","created_at":"2025-07-24 08:52:44","extension":"jpg","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":102490,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cu\u003e\u003cstrong\u003eGraphical Abstract\u003c/strong\u003e\u003c/u\u003e\u003c/p\u003e","description":"","filename":"GraphicalAbstract.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7196752/v1/41b795a4082c531aa9b68da0.jpg"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eExperimental investigation of CTOD fracture toughness in FCAW-GS welds of offshore jacket structure\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eOffshore renewable energy wind farms and oil and gas industries necessitate offshore jacket structures in deep water having high fracture toughness materials such as low carbon steel with suitable strength and impact toughness. The works of Bai and Jin and Sanchez et al. indicate that offshore jacket structures are essential for maintaining the integrity of assets utilized in the offshore renewable energy and oil and gas operations [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e][\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. These structures are subject to active monitoring by regulatory and national authorities due to the dangers of failure and environmental impacts, as noted by Scherf et al. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. For instance, a significant failure from the occurrence of surface cracks, which have been observed in cyclically loaded structures from the standpoint of fracture mechanics, is indicated in the work by Fajuyigbe and Brennan [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] and Maljaars et al. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. According to the study of Fondjo and Dzogbewu [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], the said type of linear defects, such as cracks, can pose a greater risk than rounded defects because of their susceptibility to increasing stress, which needs to be considered in the selection of suitable destructive testing. For instance, more companies are now preventing the failures by testing material properties beyond the normal standards, like using CTOD fracture toughness, instead of correcting the issues after they happen, as pointed out by Kulkarni et al. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Additionally, Brewer and Sheets [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] state that the Charpy impact toughness test is not the optimal method for assessing fracture toughness due to its lack of accuracy and indirect relevance. Conversely, the same study indicated that the crack tip opening displacement (CTOD) test, which exceeds traditional material property assessment, is becoming increasingly favoured in the offshore sector, most especially for critical structures and pipelines. The study by Avila et al. advocates for the utilization of CTOD fracture toughness, since it is strongly endorsed for computations in fracture mechanics to assess the severity of material or weld failures and their associated microstructure [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. For example, utilizing CTOD is essential for thick-walled materials due to the significant constraint and residual stresses after welding that might result in failures, as demonstrated by Tan et al. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Consequently, applying CTOD to examine critical welds in structures is essential due to the danger from crack propagation, according to the study of Goli-Oglu and Filatov [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. In summary, the potential structural failure due to linear weld defects, which may result in crack propagation, can be alleviated by controlling weld flaws using appropriate welding conditions and employing both non-destructive and destructive testing methods. Utilizing CTOD fracture toughness, substantiated by extensive literature, is of paramount importance. Nonetheless, employing Charpy as a standalone method is inadvisable due to its indirect relevance and insufficient precision in evaluating fracture toughness.\u003c/p\u003e\u003cp\u003eThe study acknowledges the prior contributions of Coronado and Ceron regarding the CTOD fracture toughness of welds in AISI 1045 medium carbon steel shafting, characterized by a carbon content of 0.45%, welded individually using flux-cored arc welding (FCAW), submerged arc welding (SAW), and shielded metal arc welding (SMAW), serving as the foundational reference [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Furthermore, the investigation by Kitagawa and Kawasaki into the current advancements in high-strength and durable welding consumables for offshore structures serves as a key guideline in selecting the welding process for the project. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Finally, the research conducted by Setiyanto et al. regarding the application of 1.5% Ni in FCAW to enhance weldability and mechanical properties serves as a significant reference for this work in choosing the welding consumable [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThis research constitutes a novel contribution to various fields of science and engineering through the experimental investigation of a K-bevel 72 mm thick plate composed of S355 KT-40 grade, full welding via flux-cored arc welding with gas shielding (FCAW-GS) in a horizontal orientation (2G), employing CTOD fracture toughness testing to evaluate the welds in offshore jacket structures, supplemented by statistical analysis and numerical modelling. This work investigates CTOD fracture toughness in the theoretical design, construction execution, and potential repair maintenance of offshore jacket structures to mitigate crack propagation in welds. Moreover, preselecting welding parameters and performing material testing through appropriate non-destructive testing and suitable destructive testing for the welded experiment are essential for tackling weldability issues and guaranteeing weld integrity, respectively.\u003c/p\u003e\u003cp\u003eThe primary aim of the study is to avert weld failures resulting from material or weld flaws that may induce crack propagation. This can improve general safety for all inhabitants, maximize asset efficiency, and extend equipment longevity. The succeeding objectives include welding the joint, non-destructive testing using magnetic particles and ultrasonics, and destructive testing using macro-examination, microhardness, tensile, microscopy, CTOD fracture toughness, and Charpy tests. The microscopy at magnifications of 25x and 100x is concentrated on GCHAZ to ascertain the position of fatigue cracks, determine the microstructure phases, and to quantify the corresponding grain sizes in the grain-coarsened heat-affected zone or within 0.5 mm from the fusion line. Moreover, conduct statistical analysis utilizing a one-way ANOVA to investigate the significant differences in crack lengths, Charpy impact values, and microhardness with respect to measurement regions. Additionally, assess and analyze the trend and correlation between load and displacement relative to CTOD through mesh and contour plots. Finally, model the measured crack lengths using numerical fitting and a quadratic equation to define the location of the optimal crack length, an important factor in fracture mechanics.\u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cp\u003eThis section delineates the materials and methods in accordance with the established objectives.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Experimental welding\u003c/h2\u003e\u003cp\u003eThe experiment entails the use of parallel K-bevel joint preparations made from S355 KT-40 material grade, with a thickness of 72 mm, each joint member is measuring 2000 mm in length and 350 mm in width. The junction was welded utilizing complete flux-cored arc welding with gas shielding (FCAW-GS) in a horizontal position. A study indicates that FCAW-GS provides superior weld quality and cleaner welds than self-shielded flux-cored arc welding (FCAW-SS). Both employ flux-cored wire; however, FCAW-GS incorporates an external shielding gas to safeguard the weld against ambient contamination, yielding a smoother finish and reduced spatter [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. When CO₂ is utilized in FCAW, it is subjected to the arc's heat, resulting in its decomposition into carbon monoxide and oxygen, so generating energy that amplifies the arc's heat, penetration, and fluidity [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. This exothermic reaction, along with the gas's elevated thermal conductivity, results in a deeper and wider weld penetration profile, rendering it appropriate for welding thicker materials [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. To check for hydrogen cracking susceptibility, there is a 48-hour delay after welding. Before moving on to destructive testing, non-destructive testing using manual ultrasonics and magnetic particle inspection is carried out to determine the integrity of the welds.\u003c/p\u003e\u003cdiv id=\"Sec4\" class=\"Section3\"\u003e\u003ch2\u003e2.1.1. Chemical composition of base material and welding consumable\u003c/h2\u003e\u003cp\u003eThe welding experiment employs S355 KT-40 plate and welding consumables, with their chemical compositions specified in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The chemical compositions were assessed according to the standard welding criteria specified in AWS D1.1 [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Carbon (C) and manganese (Mn) are definitively the primary elements in both base materials and welding consumables, affecting the carbon equivalent (CE), weldability, and mechanical properties. Moreover, the concentrations of sulphur (S) and phosphorus (P) are controlled due to their potential detrimental impact on weldability, which can cause embrittlement of the weld metal. The high nickel concentration in the filler wire is evident, as nickel atoms in steel interact with carbon to improve toughness, especially at low temperatures, through various methods such as acting as austenite (FCC) stabilizer. The research by Setiyanto et al. indicates that an increase of 1.5% Ni in FCAW diminishes grain boundary ferrite and enhances resistance to cold cracking [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Furthermore, nickel reduces the martensite start (Ms) temperature, improving hardenability and refining the microstructure, which leads to increased yield strength and impact toughness [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Eon et al. assert that nickel especially promotes the formation of a refined martensite structure, distinguished by a higher density of high-angle grain boundaries, which is crucial for toughness [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eChemical composition of base metal and filler wire.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eElement\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePlate S355 KT-40, 72 mm thick\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eFCAW-GS, 1.2 mm diameter E81T1-K2C\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.04\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSi\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.20\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMn\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.23\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.009\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.014\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.0015\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCr\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.02\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNi\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.72\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.002\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTi\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.014\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCu\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNb\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.028\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCE\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNA\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section3\"\u003e\u003ch2\u003e2.1.2. Welding of joint for CTOD\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e illustrates the simulated weld, including a K-bevel joint preparation executed in a horizontal orientation, whereas Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e delineates the welding parameters employed for the joint fabrication. BSEN 1101-2 served as the basis for establishing the minimum preheat based on the welding conditions specified in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The minimum preheat, inter-run temperature, and heat input were established accordingly.\u003c/p\u003e\u003cp\u003eThe full-thickness single-edge notch bend (SENB) samples for the crack tip opening displacement (CTOD) test were covered, considering the notch location, geometry, and orientation were all in accordance with the criteria of ISO 15653 [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The CTOD test specimens were extracted from the weld center and the grain-coarsened heat-affected zone regions (GCHAZs) or within 0.5 from the fusion line. The weld centerline (WCL) is a primary focus of the investigation due to its propensity for crack initiation, attributed to flaws such as slag inclusion, porosity, lack of inter-run fusion, and metallurgical alterations due to dilution [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. These defects can function as stress concentrators, making the weld metal more vulnerable to failure. Furthermore, fusion lines between the base metal and the weld or (GCHAZs) are investigated due to historical metallurgical discrepancies, such as the chemical composition of the parent metal and welds between adjacent materials, which might initiate failure [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Conversely, because of the low-carbon steel composition of the base metals and welding consumables, the likelihood of brittle martensite formation leading to hydrogen or heat-affected zone cracking is minimal, resulting in a lower priority for scrutiny [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn summary, this study investigates the relationship between weld metal (WM) and grain-coarsened heat-affected zone (GCHAZ) in connection to CTOD while also performing destructive testing, including tensile, Charpy, and microhardness tests, along with microscope analysis to check the integrity of the welds.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eWelding parameters of offshore jacket structure.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eItem\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eValue/Details\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003eBase Metal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eThickness (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e72\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSpecification\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eS355 KT-40\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCarbon Equivalent (CE)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.37\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eYield strength (MPa)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e390\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003eJoint\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWeld joint type\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eK-bevel\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBevel Angle\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e45\u0026ndash;50\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWeld category\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eOriginal weld\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBack gouging\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePosition\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWelding position\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2G (horizontal)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eWelding Process\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eProcess mode\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eConstant Voltage (FCAW-GS)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eTransfer mode\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSpray\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e\u003cp\u003eElectrical Characteristics\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePolarity\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDCEP\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCurrent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRoot: 190\u0026ndash;230 A; Rests: 200\u0026ndash;240 A\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVoltage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e21\u0026ndash;25 V\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHeat input (kJ/mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRoot: 0.9\u0026ndash;2.3; Rests: 1.0\u0026ndash;2.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eArc efficiency\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eGas\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eShielding\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePurely CO₂\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFlow rate (L/min)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e20\u0026ndash;25\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e\u003cp\u003eTechnique\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMethod of back gouging\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCarbon arc air gouging\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eString or Weaving\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eBoth\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMaximum weaving (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e17\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eElectrode extension (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e15\u0026ndash;25\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eInter-pass cleaning\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eChipping, grinding, and bopping\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTemperature\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMinimum preheat temperature (\u0026deg;C)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e110\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMaximum inter-run temperature (\u0026deg;C)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e243\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.2. Methods of non-destructive testing\u003c/h2\u003e\u003cp\u003eThe welded specimen, made of ferrous material, utilizes AC (alternating current) magnetic particle inspection (MPI) in accordance with ASME V. Alternating current (AC) is favored over direct current (DC) due to its ability to identify surface and slightly subsurface discontinuities, attributed to the \"skin effect,\" which concentrates the magnetic field near the surface, rendering it optimal for detecting surface fractures [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The weld joint is inspected 48 hours post-welding to ensure it is not susceptible to hydrogen cracking prior to non-destructive testing. This delay permits adequate time for hydrogen, which may induce delayed cracking, to diffuse from the weld and perhaps render the cracking observable [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. The weld surface and base material are cleansed before inspection to ensure accurate assessment. Required materials comprise the AC magnetic yoke, wet-visible black particles, and white contrast paint. Magnetic particle inspection (MPI) is performed at temperatures not surpassing 50\u0026deg;C, with defect analysis conducted under 500 lux illumination [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. White contrast paint is applied to the cleaned and dried surfaces of the base material and weld during inspection. Wet-visible black particles are applied using the AC magnetic yoke angled at 45\u0026ndash;60\u0026deg; over the weld or parent material until the entire welded specimen is thoroughly coated [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Defects in welds and materials discovered during testing are recorded and measured using a steel ruler, including the location, length, width, and/or diameter of each flaw.\u003c/p\u003e\u003cp\u003eThe specimen's thickness is 72 mm, rendering radiography impractical. Iridium-192 necessitates an extended exposure duration to get adequate imaging. A limitation of radiography concerning substantial wall thickness is its challenge in identifying planar defects, including lack of sidewall fusion, fractures, and laminations. Ultrasonic testing is optimal for thick-walled materials and proficient in identifying both planar and volumetric flaws in material. Manual ultrasonic testing (UT) employs A, B, C, and D scans in accordance with ASME V standards [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The A-scan displays three signal echoes: the initial echo on the left signifies the metal surface where the probe is placed; the central echo denotes the defect; and the final echo on the right represents the back wall surface of the material. B, C, and D represent the lateral, superior, and terminal perspectives of the welds, respectively [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The weld and base metal, along with the required surface area of scanning, are thoroughly cleaned before testing to ensure effective scanning and probe connection or coupling efficiency. Finally, significant indications are sketched and recorded and ensure proper evaluation for acceptance or rejection of the inspected weld joint.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e2.3. Methods of destructive testing\u003c/h2\u003e\u003cp\u003eUpon the successful completion of nondestructive testing, destructive mechanical testing is conducted, encompassing tensile testing, macro-examination, microhardness assessment, Charpy impact toughness evaluation, CTOD fracture toughness analysis, and microscopy. Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e delineates the scope of destructive testing of welds, while the details are elaborated in the subsequent subsections. According to Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the test points and notch location for the destructive testing are displayed in the corresponding figures.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eScope of destructive testing.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDestructive testing method\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003eOffshore jacket structure\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLocation of test\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eTotal specimen\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eFigure\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMacro-examination\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWeld with HAZ\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMicrohardness 22\u0026deg;C\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWM, HAZ \u0026amp; BM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1 (68 test points)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4, 13\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTensile at 22\u0026deg;C\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAll-weld longitudinal \u0026amp; transverse\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eASTM A370\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCharpy at -40\u0026deg;C\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWCL, FL, FL\u0026thinsp;+\u0026thinsp;2 mm, FL\u0026thinsp;+\u0026thinsp;5 mm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10 x 3\u0026thinsp;=\u0026thinsp;30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e14\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCTOD at 0\u0026deg;C\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWCL and GCHAZ (within 0.5mm from FL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMicroscopy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOptical (25x and 100x)\u0026mdash;GCHAZ, FL \u0026amp; crack tip, grain size \u0026amp; microstructure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3 x 2\u0026thinsp;=\u0026thinsp;6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7\u0026ndash;11\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section3\"\u003e\u003ch2\u003e2.3.1. Macro-examination and microhardness\u003c/h2\u003e\u003cp\u003eISO 17639 is employed to produce specimens intended for macro-examination, assessing weld quality, detecting material defects, and determining the sequence of weld passes. The specimen is magnified by a factor of 10 in compliance with ASTM E340 criteria. Flux-cored arc welding (FCAW) is employed to perform welds that may exhibit defects such as porosity, slag, copper inclusions, and lack of fusion. The total number of runs can be evaluated and measured by a macro-analysis. In addition to macro-examination, a microhardness test is performed to evaluate if the heat-affected zones (HAZs) and weld metal are below the maximum hardness requirement. The aim for microhardness is to attain a lower average value in the weld relative to the heat-affected zone, with all values remaining below 325 Hv5 [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The sample examinations are performed utilizing the macro-specimen.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section3\"\u003e\u003ch2\u003e2.3.2. Tensile testing\u003c/h2\u003e\u003cp\u003eThe welds undergo one all-weld longitudinal and one transverse tensile test in accordance with ASTM A370 to provide confidence prior to CTOD fracture toughness testing [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The principal criteria are tensile strength (\u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e) and yield stress (\u003cem\u003eRp\u003c/em\u003e\u003csub\u003e\u003cem\u003e0.2\u003c/em\u003e\u003c/sub\u003e), documented to confirm their compliance with the base material and their capacity to withstand load without failure. The \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eRp\u003c/em\u003e\u003csub\u003e\u003cem\u003e0.2\u003c/em\u003e\u003c/sub\u003e must reach or surpass the values recommended for ST355 KT-40 base metal\u0026rsquo;s specification. The applied force and the tension at both extremities of the specimen are quantified and documented. \u003cem\u003eRp\u003c/em\u003e\u003csub\u003e\u003cem\u003e0.2\u003c/em\u003e\u003c/sub\u003e represents the greatest stress the weld material can withstand within its elastic limit, whereas \u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e denotes the ultimate stress prior to failure [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Ultimately, elongation is quantified by the variation in length after the tensile test relative to the original length.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section3\"\u003e\u003ch2\u003e2.3.3. Charpy impact toughness testing at -40\u0026deg;C\u003c/h2\u003e\u003cp\u003eThe Charpy impact toughness test is performed at -40\u0026deg;C in accordance with ASTM A370, with specimens collected from the weld center, fusion line (FL), FL\u0026thinsp;+\u0026thinsp;2 mm, and FL\u0026thinsp;+\u0026thinsp;5 mm, which are the suspected regions influenced by welding. The impact toughness of a weld is evaluated by measuring the energy absorbed during fracture under an impact load [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. It is utilized to assess the ability of a weld to endure sudden shocks and impacts, hence establishing its appropriateness for application in offshore jacket structures at a minimum design temperature of -40\u0026deg;C. The goal is to achieve a minimum value of 40 J to match the impact toughness of the base metal.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section3\"\u003e\u003ch2\u003e2.3.4. Crack tip opening displacement\u003c/h2\u003e\u003cp\u003eFracture propagation in materials can be evaluated using the crack tip opening displacement (CTOD) test with a single-edge notch bend (SENB) specimen, as per ISO 15653 [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. This test is appropriate for structures where the principles of Linear Elastic Fracture Mechanics (LEFM) can be employed to evaluate the fracture properties of low-carbon steel weldments, especially when the material exhibits primarily linear elastic behavior and the plastic zone near the crack tip is insignificant relative to the crack length [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The CTOD test evaluates a material's ductility by replicating the propagation of a fatigue fracture, facilitating the assessment of significant flaw size. The CTOD specimen geometry consists of four primary phases [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. The test specimen is initially machined and subjected to fatigue or pre-cracking within defined specifications at a temperature of 22\u0026deg;C. The final phase involves fracturing the specimen under controlled conditions at a temperature of 0\u0026deg;C, followed by an analysis of the specimen and the associated data to ascertain the CTOD value.\u003c/p\u003e\u003cdiv id=\"Sec12\" class=\"Section4\"\u003e\u003ch2\u003e2.3.4.1. Prefatigued fracture and pre-cracking of CTOD specimen\u003c/h2\u003e\u003cp\u003ePrefatigued fracture and pre-cracking at ambient temperature are conducted in accordance with ISO 12135 prior to CTOD fracture toughness evaluation [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. To facilitate the initiation of a fatigue crack, a machined notch is incorporated into the specimen, owing to the challenges associated with generating a genuine fatigue fracture [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. To ensure the accuracy of the CTOD test, the pre-cracking must include the elastic-plastic region. For accurate CTOD fracture toughness testing, the fatigue pre-cracking must be exact within \u0026plusmn;\u0026thinsp;2.5%, and for three-point bend specimens, the maximum fatigue pre-cracking force during the final 1.3 mm or 50% of pre-crack extension must comply with ISO 12135 [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section4\"\u003e\u003ch2\u003e2.3.4.2. Cracking and measurement of CTOD\u003c/h2\u003e\u003cp\u003eBS 7448-part 2 is utilized for the assessment and verification of CTOD and its related parameters, including applied force, crack length, displacement, stress intensity factor, and the specimen's width and thickness, as well as tensile, among others. [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. The progression of the crack is observed and graphed with load against displacement. The crack tip opening displacement (CTOD) is measured using the clip gauge method, a technique utilized to assess fracture toughness in materials. It utilizes two clip gauges in accordance with ISO 15653, one fixed at the crack mouth opening displacement and the other positioned at the crack tip, to evaluate the crack opening displacement at two distinct points. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. This method optimizes the CTOD measurement process and is widely employed, particularly in weld applications. The objective for CTOD is to achieve a minimum value of 0.15 mm, as stipulated by DNV-OS-C401. [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. This value serves as a threshold to guarantee that a material can withstand crack propagation and avert brittle fracture under stress. [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec14\" class=\"Section4\"\u003e\u003ch2\u003e2.3.4.3. Modes of CTOD fracture\u003c/h2\u003e\u003cp\u003eThe research has employed four modes of fracture [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Initially, M-mode demonstrates a terminal fracture with decreasing stress, with the fracture surface showing indications of tearing. Secondly, U-mode demonstrates a terminal fracture when subjected to increasing stress, with the fracture surface exhibiting ripping [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Thirdly, C-mode demonstrates the ultimate fracture with increasing strain, and the fracture surface shows no signs of ripping [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Finally, a pop-in represents the fourth form of fracture that occurs when the load rebounds to surpass the starting condition after either a load reduction, an increase in displacement, or both [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. The aim for fracture mode is to achieve a minimum of U-mode for optimal outcomes.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec15\" class=\"Section3\"\u003e\u003ch2\u003e2.3.5. Microscopy at 25x and 100x\u003c/h2\u003e\u003cp\u003eMicroscopy is performed at 25x magnification to visualize the fatigue crack and at 100x to ascertain the grain size number according to ASTM E112 [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The aim of microscopy is to analyze grain size and determine the microstructure of the GCHAZ, a region strongly suspected of weld failure due to potential grain growth [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Additionally, weld microstructure images are examined in correlation with CTOD values. The expected grain size is between 10 and 100 \u0026micro;m for optimal corrosion resistance [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], while the microstructure should predominantly consist of ferrite and pearlite, with minimal martensite.\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003e2.4. Statistical Analysis\u003c/h2\u003e\u003cp\u003eDestructive testing results are analysed using statistical techniques. An advanced one-way ANOVA assesses the significant difference of crack length, Charpy, and microhardness with respect to the measurement locations using a 95% confidence interval by using the p-value and F-critical as the references to either accept or reject the null hypothesis [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Finally, unique mesh and contour plots visualize the relationship, trend, and distortion between CTOD and the load and displacement.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\u003ch2\u003e2.5. Numerical modelling\u003c/h2\u003e\u003cp\u003eA novel approach for ascertaining the average or optimal crack length is presented, utilizing mathematical fitting and the quadratic equation of a parabolic curve as an alternative to traditional methods as described by Eq.\u0026nbsp;1. The vertex of the parabola determines the optimal crack length, which is a critical parameter in fracture mechanics to ascertain the integrity of materials, such as the ratio of average crack length to width ratio (\u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003eo\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e/W\u003c/em\u003e) [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\u003ch2\u003e3.1. Results of actual welding experiment\u003c/h2\u003e\u003cp\u003eThe study aims to conduct the welding experiment in compliance with design codes and standards, incorporating a detailed welding procedure specification to obtain a tough weld. The heat input was maintained within the specified range, as it is a crucial welding parameter for regulating the toughness of the weld [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e], which is affected by the weldability of the base materials, including their thickness and carbon equivalent [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Moreover, the impact of alloying elements was controlled, especially the carbon concentration, which can alter the \u003cem\u003eAc\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e (transformation of ferrite to austenite), \u003cem\u003eAc\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e (initiation of austenite formation), and \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e (formation of martensite) [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e][\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. The utilization of low carbon inhibits a high proportion of martensite, thus diminishing hardness and vulnerability to hydrogen and heat-affected zone cracking while enhancing ductility [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e][\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. Furthermore, enhanced weldability and mechanical properties are achieved by keeping low levels of sulfur and phosphorus [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e][\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. The chemical composition of base metal and welding consumables was meticulously controlled to provide optimal cooling rates and yield good mechanical properties of the welds [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. In summary, the weld's microstructures mostly comprise ferrite and pearlite, leading to improved ductility and fracture toughness. The evidence comprises microscopy images, Charpy impact toughness, and CTOD data, which are discussed in the following sections.\u003c/p\u003e\u003cp\u003eIn conclusion, superior welds are achieved by the judicious selection of compatible base metals and welding consumables, optimal welding settings, skilled welders, effective supervision, and the use of suitable welding tools, equipment, and instruments.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec20\" class=\"Section2\"\u003e\u003ch2\u003e3.2. Results of non-destructive testing\u003c/h2\u003e\u003cp\u003eMagnetic particle testing is a visual aid method employed to detect surface and near-surface flaws of the welds and adjacent base metal [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Moreover, ultrasonics is a precise technique utilized for identifying both internal and external material defects, with accuracy up to 10 microns. The test results documented random volumetric indications in three locations near the root, with a maximum dimension of 1.5 mm, which are deemed acceptable per AWS D1.1 standards [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn conclusion, the non-destructive tests conform to AWS D1.1 requirements, signifying that the welds are suitable for destructive testing.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec21\" class=\"Section2\"\u003e\u003ch2\u003e3.3. Results of destructive testing\u003c/h2\u003e\u003cp\u003eAfter the non-destructive inspection, the welded joint was subjected to destructive testing, encompassing macro-examination, microhardness assessment, tensile testing, CTOD fracture toughness evaluation, and microscopy analysis, as detailed in the following subsections.\u003c/p\u003e\u003cdiv id=\"Sec22\" class=\"Section3\"\u003e\u003ch2\u003e3.3.1. Macro-examination and microhardness\u003c/h2\u003e\u003cp\u003eA macro-examination was conducted to confirm the acceptability of the weld before proceeding to other destructive testing methods. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e illustrates that the weld contains a minor flaw of 1 mm slag inclusion at the root, which is permissible according to AWS D1.1 [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. An acceptable weld is attained by the regulation of welding factors, consumables, base metal, and the proficiency of the welder. Welds with minimal discontinuities significantly enhance mechanical properties, including tensile strength and toughness, while welds with substantial defects create additional voids, compromising metallic bonding and leading to reduced tensile strength and toughness [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]. Moreover, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e depicts the microhardness graphs for the left and right sides of the weld joint derived from the macro specimen. The hardness of the central region with root and other weld regions are assessed using one-way ANOVA. The disparity in weld values is not an issue; nonetheless, it is crucial that microhardness values remain below 325 Hv5 according to EEMUA 158 [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The microhardness illustrated in Figs.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e and \u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e indicates that the heat-affected zones exhibit greater hardness than the weld metal. The discovery aligns with the research of Celin and Burja, demonstrating that the heat-affected zone cools more rapidly than the weld center, leading to the development of hard martensitic products with increased hardness [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. Furthermore, lower microhardness values at the weld center result from tempering, which enhances ductility and hardness [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn summary, the macro-examination photos showed that the welds are accepted and have no significant defects, and the micro-hardness results meet EEMUA requirements, providing confidence that the welds are suitable for Charpy and CTOD tests.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec23\" class=\"Section3\"\u003e\u003ch2\u003e3.3.2. Tensile testing\u003c/h2\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e presents the results of the tensile testing conducted at room temperature. The recorded values of yield stress and tensile strength are above the base metal\u0026rsquo;s specified tensile properties. The all-weld longitudinal test is conducted just on weld metal or parallel to the weld length concerning the CTOD specimen, whereas the transverse tensile specimen is extracted across the weld metal and heat-affected zone for the CTOD of GCHAZ specimen. Yield stress data are required as an input parameter in CTOD, which is calibrated to correspond with the CTOD test temperature at 0\u0026deg;C. These tensile specimens are utilized to assess the properties of weld metal, including tensile strength, ductility, and hardness, including defects and unusual inclusions. The rationale is that longitudinal tensile specimens typically demonstrate superior strength and toughness compared to transverse specimens, owing to the alignment of the material's grain structure with the applied force in the longitudinal direction [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]. On the other hand, transverse specimens experience force perpendicular to the grain direction, rendering them more vulnerable to fracture along the weaker grain boundaries [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn summary, tensile testing accurately assesses the properties of the weld and heat-affected zone before CTOD testing, which are enhanced by the base metal and welding consumable compositions, welding parameters, and the absence of significant defects in the welds.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec24\" class=\"Section3\"\u003e\u003ch2\u003e3.3.3. Charpy impact toughness at -40\u0026deg;C\u003c/h2\u003e\u003cp\u003eBefore CTOD testing, Charpy impact toughness is assessed at the weld metal, fusion line (FL), fusion line plus 2 mm (FL\u0026thinsp;+\u0026thinsp;2 mm), and fusion line plus 5 mm (FL\u0026thinsp;+\u0026thinsp;5 mm), which are anticipated areas of metallurgical change affected by welding. The outcomes are presented in Table\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e and illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e. All recorded values exceed the threshold of 40 J for both individual and average measurements. The satisfactory attainment of Charpy impact toughness is realized by the judicious selection of the chemical composition of the base metal and welding consumables, encompassing filler wire and appropriate shielding gas to control the microstructure [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e]. Furthermore, selecting welding consumables such as nickel contents and other alloying elements, utilizing multi-pass welding for tempering the previous bead welds, and managing the heat input within the designated range are advantageous for regulating grain size [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn conclusion, the Charpy impact toughness test has been successfully conducted, instilling confidence in the execution of the CTOD test. One-way ANOVA is utilized to conduct thorough Charpy impact toughness analyses of the substantial variations in measurement regions, as outlined in section \u003cspan refid=\"Sec28\" class=\"InternalRef\"\u003e3.4.1\u003c/span\u003e.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec25\" class=\"Section3\"\u003e\u003ch2\u003e3.3.4. Crack Tip Opening Displacement (CTOD)\u003c/h2\u003e\u003cp\u003eThe objective of the CTOD fracture toughness test is to assess the welds' resistance to crack propagation, utilizing the applicable pre-cracking and cracking parameters outlined in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e illustrates the measurement of crack length utilizing Eq.\u0026nbsp;1 to compute the average crack length. The six specimens, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, depicted the fracture surfaces taken from the weld center and grain-coarsened heat-affected zones (GCHAZs). Underneath each specimen is the corresponding load vs. extension curve, which categorizes the corresponding mode of fracture. Table\u0026nbsp;\u003cspan refid=\"Tab9\" class=\"InternalRef\"\u003e9\u003c/span\u003e indicates the sizes of the average crack length (\u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003eo\u003c/em\u003e\u003c/sub\u003e), which was used to calculate the value of \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003eo\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e/W\u003c/em\u003e, where \u003cem\u003eW\u003c/em\u003e is the width of the specimen.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eEquation 1. \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{a}_{0}=\\frac{1}{8}({a}_{2}+\\:{a}_{3}+{a}_{4}+{a}_{5}+{a}_{6}+{a}_{7}+{a}_{8}+\\frac{{a}_{1}+{a}_{9}}{2})\\:\\)\u003c/span\u003e\u003c/span\u003e[28]\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eReferring to Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, the WM-2 specimen had the lowest CTOD of 0.28 mm, while the highest was GCHAZ-1 at 2.38 mm, both having ductile crack propagation (U-mode). Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e shows that there is a total of four with U-mode, which are acceptable. The ultimate goal for a weld is to have the perfect M-mode for a stable ductile failure [\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e], which is obtained in two specimens, GCHAZ-2 and WM-3. Moreover, according to the study of Zhu et al., a material with high fracture toughness yields ductile fracture, whereas a material with low fracture toughness is susceptible to brittle fracture [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e]. In conclusion, the welds exhibit satisfactory performance, as all failures are M and U modes with CTOD values above 0.15 mm. Furthermore, welds demonstrate improved CTOD results through the utilization of low carbon, 1.7% nickel in welding consumables, and diminished residual stresses attained through suitable preheating and controlled heat input via multi-pass welding, narrow bead width, and chipping methods that yield enhanced mechanical properties [\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e describes the categorical variables with the corresponding test results of continuous variables. The location of the notch, geometry, orientation, and fracture mode are the categorical variables considered in accordance with ISO 15653 [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e delineates the notch location for six specimens. These are taken from the weld metal (WM) and grain-coarsened heat-affected zone (GCHAZ) areas, or within 0.5 mm of the fusion line, exhibiting \u003cem\u003eB x B\u003c/em\u003e (square geometry) and \u003cem\u003eNP\u003c/em\u003e orientation. \u003cem\u003eB\u003c/em\u003e represents the thickness of the specimen, whereas \u003cem\u003eNP\u003c/em\u003e refers to a specimen exhibiting through-thickness properties. Furthermore, Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e illustrates that the minimum and maximum values of the CTOD for both WM and GCHAZ specimens exhibit a significant positive correlation with displacement (\u003cem\u003eVp\u003c/em\u003e), as displacement directly quantifies CTOD in a three-point bending test. This corresponds with the findings of Khor et al., which indicate that the CTOD test measures the opening displacement at the crack tip, with displacement functioning as the plastic component of the clip gauge opening [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e]. Lastly, mesh and contour plots were used to plot the relationship of CTOD with load and displacement in Section \u003cspan refid=\"Sec29\" class=\"InternalRef\"\u003e3.4.2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eIn summary, the distinct number of specimens utilized for CTOD testing precisely characterized the fracture toughness properties of the weld metal and grain-coarsened heat-affected zone. The fracture toughness of CTOD is improved by controlled welding parameters and standard testing conditions.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePre-cracking and cracking parameters.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e\u003cp\u003ePre-cracking and cracking parameters\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLoading Span (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eB\u003c/em\u003e (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e/W\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePre-cracking temperature (\u0026deg;C)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCracking temperature (\u0026deg;C)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e288\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eTensile and pre-cracking parameters.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"10\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"10\" nameend=\"c10\" namest=\"c1\"\u003e\u003cp\u003eTensile and pre-cracking GCHAZ and WM at 22\u0026deg;C\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e\u003cp\u003eTensile (N/mm\u0026sup2;)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003eStress intensity factor\u003c/p\u003e\u003cp\u003e(N/mm\u0026sup3;/\u0026sup2;)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003ePre-cracking force\u003c/p\u003e\u003cp\u003e(kN)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cem\u003eRp\u003c/em\u003e\u003csub\u003e\u003cem\u003e0.2\u003c/em\u003e\u003c/sub\u003e (BM)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e (BM)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003eRp\u003c/em\u003e\u003csub\u003e\u003cem\u003e0.2\u003c/em\u003e\u003c/sub\u003e (Weld)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e (Weld)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eRp\u003c/em\u003e\u003csub\u003e\u003cem\u003e0.2\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e\u003cp\u003e(HAZ)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e (HAZ)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003ekF\u003c/em\u003e (Weld)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cem\u003ekF\u003c/em\u003e\u003c/p\u003e\u003cp\u003e(HAZ)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e\u003cem\u003eFf\u003c/em\u003e\u003c/p\u003e\u003cp\u003e(Weld)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u003cem\u003eFf\u003c/em\u003e\u003c/p\u003e\u003cp\u003e(HAZ)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e385\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e471\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e565\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e602\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e475\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e537\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1584\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1358\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e66\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e\u003cp\u003eN/mm\u003csup\u003e3/2\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c10\" namest=\"c7\"\u003e\u003cp\u003eLoading rate mm/min\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003ekF (weld)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c6\" namest=\"c4\"\u003e\u003cp\u003ekF HAZ\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003eWM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003eHAZ\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003e3956\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c6\" namest=\"c4\"\u003e\u003cp\u003e4464\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e0.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e0.42\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCTOD results.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"10\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLocation\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLocation of notch\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eGeometry*\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eOrientation*\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRp\u003csub\u003e0.2\u003c/sub\u003e\u003c/p\u003e\u003cp\u003e(Note 1)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eLoad (kN)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eVp\u003c/em\u003e (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eCTOD (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eFracture mode\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eGrain size (\u0026micro;m)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGCHAZ1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFL\u0026thinsp;\u0026lt;\u0026thinsp;0.5 mm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eB x B\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e490\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e216.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e9.64\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e2.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eU\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e31.8, 44.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGCHAZ2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFL\u0026thinsp;\u0026lt;\u0026thinsp;0.5 mm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eB x B\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e490\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e205.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e3.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.84\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e31.8, 63.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGCHAZ3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFL\u0026thinsp;\u0026lt;\u0026thinsp;0.5 mm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eB x B\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e490\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e173.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eU\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e44.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWM1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWCL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eB x B\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e580\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e191.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e2.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eU\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWM2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWCL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eB x B\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e580\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e183.01\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eU\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWM3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWCL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eB x B\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e580\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e194.54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"10\" nameend=\"c10\" namest=\"c1\"\u003e\u003cp\u003eNotes:\u003c/p\u003e\u003cp\u003e1. Rp\u003csub\u003e0.2\u003c/sub\u003e is reported as yield stress and corrected to the CTOD test temperature, 0\u0026deg;C.\u003c/p\u003e\u003cp\u003e2. Young's modulus of elasticity\u0026thinsp;=\u0026thinsp;207000 N/mm\u0026sup2; and Poisson's ratio\u0026thinsp;=\u0026thinsp;0.3.\u003c/p\u003e\u003cp\u003e* Please refer to ISO 15653 Annex A.\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec26\" class=\"Section3\"\u003e\u003ch2\u003e3.3.5. Microscopy\u003c/h2\u003e\u003cp\u003eThe microscopic examination concentrated on the grain-coarsened heat-affected zone (GCHAZ) within 0.5 mm of the fusion line, as previously noted, due to the anticipated onset of failure resulting from metallurgical alterations. Figures\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e to \u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e display microscope images of the GCHAZs of the fractured specimen depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, including samples with the associated CTOD values in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. The welds demonstrate that BCC pearlite and ferrite are the primary constituents, resulting in improved ductility. Pearlite consists of alternating layers of ferrite (α-iron) and cementite (Fe₃C), appearing as small, lath-like structures within the ferrite matrix [\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e]. Furthermore, due to the ferrous nature of the microstructural phases, they demonstrate a ductile-to-brittle transition with respect to temperature, hence affecting the material's toughness [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e, and Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e depict the locations of fatigue fractures and the corresponding GCHAZ regions, while Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e, and Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e provide the relevant grain size numbers of the GCHAZs according to ASTM E112, which are 6\u0026ndash;7, 5\u0026ndash;7, and 6, respectively [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. According to ASTM E112 Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, grain size numbers 7, 6, and 5 equate to 31.8, 44.9, and 63.5 \u0026micro;m, respectively [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The measured grain size values fall within the corrosion resistance range for low carbon steel, which is 10 to 100 \u0026micro;m [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Consequently, correlating grain size with the acquired CTOD values of GCHAZs will prove to be difficult. The research by Cathapuram and Lagad indicates that CTOD fracture toughness is not exclusively dependent on grain size, since a decrease in grain size of ferrous materials will increase hardness and may trigger a ductile-to-brittle transition [\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e]. Additional factors influencing fracture toughness include base metal thickness, welding carbon and nickel contents, other alloying elements, and welding parameters. The conclusion is consistent with the studies conducted by Inoue et al. [\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e] and Hanamura et al. [\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e], suggesting that reduced grain sizes and additional improvement techniques can increase toughness, hence improving CTOD.\u003c/p\u003e\u003cp\u003eIn summary, the ferrite and pearlite microstructural phases of the GCHAZs exhibit ductility, and the grain sizes of the said region are suitable for corrosion resistance. These indicate that the examined weld region possesses optimal mechanical properties, including tensile strength, impact resistance, and fracture toughness.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec27\" class=\"Section2\"\u003e\u003ch2\u003e3.4. Statistical analysis\u003c/h2\u003e\u003cdiv id=\"Sec28\" class=\"Section3\"\u003e\u003ch2\u003e3.4.1. One-way ANOVA\u003c/h2\u003e\u003cp\u003eThe investigation progresses by employing one-way ANOVA box plots to analyze the significant differences in microhardness, Charpy impact toughness, and fracture lengths about their measurement locations at a 95% confidence interval. Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, along with Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e, demonstrate that the F-statistic values are significantly lower than the F-critical values, while the p-values are below 0.05, indicating a highly significant difference in the means of microhardness and Charpy impact toughness relative to their measurement locations. The minor inconsistencies in welds produced by semi-automatic welding processes, such as FCAW-GS, may elucidate the differences compared to those generated by fully automated methods. The variation in welding effects over different areas of a weld joint can lead to non-homogenous material properties within the weld regions [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. This finding is consistent with ISO 15653, which justifies the requirement for CTOD fracture toughness across all variations [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Figure\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e illustrates that the heat-affected zones (HAZs) region has the highest mean microhardness as compared to the weld metal (WM) region. WM has better mechanical properties since the fusion zone lacks an additional weld that would temper the region [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. Furthermore, the cooling period of the HAZ is more rapid than that of the weld, resulting in smaller grains and some martensite microstructure, which yield higher microhardness values compared to the weld [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. Conversely, referring to Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e, the Charpy impact toughness of the fusion line plus 5 mm (FL\u0026thinsp;+\u0026thinsp;5) exhibits the highest mean, as the base metal region remains largely unaffected by metallurgical alterations during welding, whereas the weld metal demonstrates the lowest toughness due to significant impacts from the welding process, resulting in non-uniform material properties of the weld region [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. Nevertheless, certain sections of the fusion lines (FL and FL\u0026thinsp;+\u0026thinsp;2) exhibit impact toughness inferior to that of the weld metal (WM) due to insufficient tempering. [\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e]. Xiao et al. assert that tempering enhances mechanical properties, including ductility and toughness [\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e]. Finally, Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003e illustrates outliers of diminished values for the measure of crack lengths; the average measurements obtained from the crack edge may be inferior to those at the center due to the fracture's geometry and the applied stress [\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e]. Figure\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003e indicates that the mean crack lengths from the measurement zones exhibit no significant difference, as the F-statistic exceeds the F-critical value and the P-value is more than 0.05, attributable to the use of standard, precise input variables and fracture toughness properties of the material.\u003c/p\u003e\u003cp\u003eIn summary, employing advanced one-way ANOVA successfully analyzes the significant differences of critical variables concerning their measurement locations. Microhardness and Charpy impact toughness exhibit substantial variations based on their measurement locations, caused by metallurgical alterations, whereas average crack lengths from 6 groups show no significant differences.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMicrohardness measurements and one-way ANOVA analysis.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"14\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eBM (Hv5)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003eWM (Hv5)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"9\" nameend=\"c14\" namest=\"c6\"\u003e\u003cp\u003eHAZ (Hv5)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e194\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e212\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e175\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e204\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e217\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e201\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e218\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e181\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e234\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e219\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e152\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e198\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e202\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e197\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e240\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e153\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e201\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e209\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e193\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e223\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e165\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e197\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e207\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e203\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e202\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e157\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e197\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e222\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e207\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e201\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e169\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e206\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e228\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e220\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e187\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e154\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e207\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e213\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e191\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e212\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e203\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e211\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e228\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e182\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e206\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e207\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e214\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e178\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e211\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e213\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e211\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e197\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003e206\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e205\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e199\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e216\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e215\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e185\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e213\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e202\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e177\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e227\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e216\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e201\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e246\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e225\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e216\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e227\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"14\" nameend=\"c14\" namest=\"c1\"\u003e\u003cp\u003eSummary\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGroups\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003eCount\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e\u003cp\u003eSum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u003cp\u003eAverage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003eVariance\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e\u003cp\u003e2171\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u003cp\u003e180.9167\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e593.9015\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e\u003cp\u003e3330\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u003cp\u003e208.125\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e66.25\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHAZ\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003e40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e\u003cp\u003e8304\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u003cp\u003e207.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e308.759\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"14\" nameend=\"c14\" namest=\"c1\"\u003e\u003cp\u003eANOVA\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSource of Variation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eSS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c6\" namest=\"c4\"\u003e\u003cp\u003edf\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003eMS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003eF-statistic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c13\" namest=\"c11\"\u003e\u003cp\u003eP-value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eF-critical\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBetween Groups\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003e7118.718627\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c6\" namest=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e3559.359\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e11.82314\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c13\" namest=\"c11\"\u003e\u003cp\u003e4.18E-05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e3.138142\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWithin Groups\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003e19568.26667\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c6\" namest=\"c4\"\u003e\u003cp\u003e65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e301.0503\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c13\" namest=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003e26686.98529\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c6\" namest=\"c4\"\u003e\u003cp\u003e67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c13\" namest=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab8\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCharpy impact toughness measurements and one-way ANOVA analysis.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"14\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003eFL (J)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c7\" namest=\"c4\"\u003e\u003cp\u003eFL\u0026thinsp;+\u0026thinsp;2 mm (J)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u003cp\u003eFL\u0026thinsp;+\u0026thinsp;5 mm (J)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003eWM (J)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003e246.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c7\" namest=\"c4\"\u003e\u003cp\u003e83.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e124.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003e112\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c7\" namest=\"c4\"\u003e\u003cp\u003e73.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e103\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003e133\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c7\" namest=\"c4\"\u003e\u003cp\u003e112.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e97.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003e145.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c7\" namest=\"c4\"\u003e\u003cp\u003e300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e172.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003e171.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c7\" namest=\"c4\"\u003e\u003cp\u003e52.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e177.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u003cp\u003e160.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c7\" namest=\"c4\"\u003e\u003cp\u003e258.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e180.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c7\" namest=\"c4\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e197.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c7\" namest=\"c4\"\u003e\u003cp\u003e184.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e191\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c7\" namest=\"c4\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c11\" namest=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c14\" namest=\"c12\"\u003e\u003cp\u003e204.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"14\" nameend=\"c14\" namest=\"c1\"\u003e\u003cp\u003eSummary\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eGroups\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003eCount\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003eSum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003eAverage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003eVariance\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eFL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e1800\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e300\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eFL\u0026thinsp;+\u0026thinsp;2 mm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e1666.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e185.1667\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e11300.06\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eFL\u0026thinsp;+\u0026thinsp;5 mm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e2232.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e186.0333\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e4124.704\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eWM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c5\" namest=\"c3\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e\u003cp\u003e969.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c12\" namest=\"c10\"\u003e\u003cp\u003e161.5667\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e2167.843\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"14\" nameend=\"c14\" namest=\"c1\"\u003e\u003cp\u003eANOVA\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSource of Variation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003eSS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003edf\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003eMS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003eF-statistic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c13\" namest=\"c11\"\u003e\u003cp\u003eP-value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003eF-critical\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBetween Groups\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003e73042.4297\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e24347.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e4.815974\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c13\" namest=\"c11\"\u003e\u003cp\u003e0.007676\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e2.93403\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWithin Groups\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003e146611.42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e5055.566\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c13\" namest=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003e219653.8497\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"3\" nameend=\"c13\" namest=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab9\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 9\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCrack length measurements and one-way ANOVA analysis.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCrack length\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGCHAZ-1 (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003eGCHAZ-2 (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eGCHAZ-3 (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eWM-1 (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003eWM-2 (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eWM-3 (mm)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ea\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e39.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e38.97\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e39.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e39.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e38.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e38.97\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ea\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e39.95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e39.61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e40.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e40.04\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e39.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e39.83\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ea\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e40.08\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e39.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e40.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e40.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e40.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e40.21\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ea\u003csub\u003e5\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e39.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e38.77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e40.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e40.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e40.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e40.05\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ea\u003csub\u003e6\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e40.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e40.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e40.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e40.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e40\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ea\u003csub\u003e7\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e39.91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e39.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e40.44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e39.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e40.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e39.24\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ea\u003csub\u003e8\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e39.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e39.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e39.83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e38.95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e39.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e38.65\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e(a\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;a\u003csub\u003e9\u003c/sub\u003e) 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e38.155\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e37.44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e38.2065\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e38.265\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e37.975\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e37.605\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAve (\u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e39.61438\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e39.07375\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e39.96331\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e39.65688\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e39.63188\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e39.31938\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"9\" nameend=\"c9\" namest=\"c1\"\u003e\u003cp\u003eSummary\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGroups\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eCount\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003eSum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003eAverage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003eVariance\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGCHAZ-1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e316.915\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e39.61438\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e0.431253\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGCHAZ-2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e312.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e39.07375\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e0.599455\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGCHAZ-3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e319.7065\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e39.96331\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e0.711039\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWM-1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e317.255\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e39.65688\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e0.565864\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWM-2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e317.055\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e39.63188\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e0.810928\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWM-3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003e314.555\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003e39.31938\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003e0.795217\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"9\" nameend=\"c9\" namest=\"c1\"\u003e\u003cp\u003eANOVA\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSource of Variation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003edf\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eF-statistic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003eP-value\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003eF-critical\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBetween Groups\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.782613\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.756523\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.15979\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e0.344824\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e2.437693\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWithin Groups\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e27.3963\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.652293\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e31.17891\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec29\" class=\"Section3\"\u003e\u003ch2\u003e3.4.2. Mesh and contour plots\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e shows mesh and contour plots, which are employed to depict the interrelationship among three variables, emphasizing a unique facet of this study. The CTOD demonstrates a strong correlation with load and displacement, as it directly measures the crack's opening behaviour at the tip under applied force, which is naturally influenced by the load and resultant material deformation [\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e]. Figure\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e also shows slight distortion observed near the midway of the load at low displacement levels. When a load is applied to a fractured component, the material deforms, leading to the advancement of the crack. The quantity of the load immediately affects the extent of deformation and, consequently, the CTOD [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e]. An augmented load generally results in a larger crack opening and an increased CTOD value, which conclude both toughness and ductility of the material.\u003c/p\u003e\u003cp\u003eIn conclusion, the generated unique mesh and contour plots accurately depict the relationship between the interaction of welds\u0026rsquo; CTOD with load and displacement.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec30\" class=\"Section2\"\u003e\u003ch2\u003e3.5. Modelling with quadratic equation\u003c/h2\u003e\u003cp\u003eAn additional innovation of the investigation is the utilization of numerical modelling with a quadratic equation, as delineated in Eq.\u0026nbsp;2. The objective is to ascertain the horizontal (x) position of the optimal crack length to model across all specimen data. The documented crack lengths from Table\u0026nbsp;\u003cspan refid=\"Tab9\" class=\"InternalRef\"\u003e9\u003c/span\u003e are graphically represented alongside the quadratic fitting line, as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e17\u003c/span\u003e. The correlation coefficient (R\u0026sup2;) of 74.7% derived from the fitting of Eq.\u0026nbsp;3 signifies a strong link, identifying a root on the x-axis of 3.937265 (unitless) or 35.435385 mm from a 72 mm specimen thickness (\u003cem\u003eB\u003c/em\u003e), which denotes the position of the optimal crack length resulting in a y-value of 40.2809 mm. This method is equally beneficial for individual specimens by analyzing their data and calculating the quadratic equation to ascertain the optimal crack length of a specimen.\u003c/p\u003e\u003cp\u003eEquation 2. \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:y={ax}^{2}+bx+c\\)\u003c/span\u003e\u003c/span\u003e {Quadratic formula}\u003c/p\u003e\u003cp\u003eEquation 3. \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:y={-0.1323x}^{2}+1.0418x+38.23\\)\u003c/span\u003e\u003c/span\u003e {Modelled quadratic equation}\u003c/p\u003e\u003cp\u003eThe application of average crack length is essential for calculating CTOD and for assessing the ratio of average crack length to specimen width (\u003cem\u003ea₀/W\u003c/em\u003e), where \u003cem\u003eW\u003c/em\u003e is the specimen width, a vital parameter in fracture mechanics that indicates the depth of a crack relative to its width [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The conventional calculation method results in a final average of \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e/W\u003c/em\u003e as 0.55, but our method generates 0.56, indicating a minimal discrepancy. The results reside within the designated range of 0.45 to 0.70 as stipulated by E1290-02 [\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e]. This ratio is essential as it directly influences the structural integrity of a material, particularly in evaluating the risk of failure under stress; a larger ratio signifies a heightened likelihood of fracture due to increased stress concentration at the crack tip [\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn summary, plotting the measured fracture lengths of a specimen and applying a quadratic fit produces a parabolic curve, representing a unique approach or an alternative to conventional methods, as illustrated in Eq.\u0026nbsp;1. The vertex of the parabola identifies the optimal crack length, corresponding to the mean crack length (\u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e), a crucial parameter in fracture mechanics.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Conclusion and Future Work","content":"\u003cp\u003eThe study examines FCAW-GS welds with a K-bevel joint design, concentrating on CTOD fracture toughness testing of the weld center and GCHAZ to mitigate failure of offshore jacket structures caused by crack propagation. The microhardness of the welds on both sides of the weld joint has a similar profile, reflecting a uniform influence of welding and cooling, with a favorable peak value of 246 Hv5, which satisfies the EEMUA 158 maximum requirement of 325 Hv5. All weld and HAZ regions exhibit exceptional impact toughness, with a minimum Charpy single value of 73.9 J and an average value of 108 J, both above the 40 J industry standard. The CTOD of CGHAZ and the weld center, with values of 0.36 mm and 0.28 mm, respectively, surpass the stipulated 0.15 mm threshold outlined in DNV-OS-C401. The microstructures of the GCHAZs have no signs of grain growth and yield a grain size ranging from 31.8 to 63.5 \u0026micro;m, indicating enhanced corrosion resistance. The tensile strength surpasses that of the base metal, with yield and ultimate tensile strength values of 565 MPa and 602 MPa, respectively. The welds adhere to industry standards, as the mechanical properties, including yield and tensile strength, microhardness, Charpy impact toughness, and CTOD fracture toughness, have achieved the requisite values, hence ensuring integrity and safety. Statistical examination utilizing one-way ANOVA, with box plots and tables, reveals no significant variation in crack lengths among groups of specimens; nonetheless, Charpy impact toughness and microhardness demonstrate substantial variances contingent upon their respective measurement locations. Furthermore, the mesh plot and contour map validate the robust association between CTOD, load, and displacement. Finally, the optimal crack length is ascertained using numerical modelling of the documented crack lengths utilizing a quadratic equation, with a yield ratio of average crack length to width of 0.56, falling within the industry standard range of 0.45 to 0.7.\u003c/p\u003e\u003cp\u003eThe findings have considerable application for both industry and academia, especially in various fields of engineering, particularly in the front-end and detailed designs, construction, installation, and maintenance of offshore jacket structures and analogous infrastructure. The CTOD tests concentrate on the GCHAZ and weld center regions, facilitating further research on the heat-affected zones or beyond the fusion lines. Finally, the data and conclusions can be utilized in future studies to enhance the assessment of fracture mechanics, hence improving the understanding of stresses and acceptance criteria for weld defects in low-carbon steel structures.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e\u003cstrong\u003eNomenclature and acronyms\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e#\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eSymbol/Acronym\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eDescription\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003eUnit\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eAlternating Current\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eA\u003csub\u003ec1\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eStart formation of austenite\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e\u003csup\u003eo\u003c/sup\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eA\u003csub\u003ec3\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eTransformation of ferrite into austenite\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e\u003csup\u003eo\u003c/sup\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003ea\u003csub\u003e0\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp class=\"ReferencesCxSpMiddle\"\u003e\u003cspan lang=\"EN-GB\"\u003eaverage\u003c/span\u003e\u003cspan lang=\"EN-PH\"\u003e\u0026nbsp;crack length, mm\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003emm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eANOVA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eAnalysis of Variance\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eASME\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eAmerican Society of Mechanical Engineers\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e\u003csup\u003e-\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eASTM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eAmerican Society for Testing and Materials\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e\u003csup\u003e-\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eAWS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eAmerican Welding Society\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eB\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp class=\"ReferencesCxSpMiddle\"\u003e\u003cspan lang=\"EN-PH\"\u003especimen thickness\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003emm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eBCC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eBody-Centred Cubic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eCE\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eCarbon Equivalent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eCTOD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eCrack Tip Opening Displacement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003emm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eEEMUA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eEngineering Equipment and Materials Users Association\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eFCAW-GS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eFlux-Cored Arc Welding Gas-Shielded\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eFCC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eFace-Centered Cubic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eFe\u003csub\u003e3\u003c/sub\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eCementite\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eFf\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003ePre-cracking force\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eFL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eFusion Line\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eGCHAZ\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eGrain-Coarsened Heat Affected Zone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eHSLA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eHigh strength low alloy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eHAZ\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eHeat affected zone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eJ\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eJoules\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eKf\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eStress intensity factor\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eLEFM\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eLinear Elastic Fracture Mechanics\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eMPI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eMagnetic Particle Inspection\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eM\u003csub\u003es\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eStart formation of martensite\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e\u003csup\u003eo\u003c/sup\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eN\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eNormal to welding direction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eParallel to welding direction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003ePAUT\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003ePhased Array Ultrasonic Testing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eQ\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eWeld thickness direction\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eRm\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eUltimate Tensile Strength (UTS)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eRp\u003csub\u003e0.2\u003c/sub\u003e\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eYield Strength (YS)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eSAW\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eSubmerged Arc Welding\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eSENB\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp class=\"ReferencesCxSpMiddle\"\u003e\u003cspan lang=\"EN-GB\"\u003eS\u003c/span\u003e\u003cspan lang=\"EN-PH\"\u003eingle-edge notched bend\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eSMAW\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eShielded Metal Arc Welding\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eW\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp class=\"ReferencesCxSpMiddle\"\u003e\u003cspan lang=\"EN-PH\"\u003especimen width\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003emm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003eWCL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eWeld centreline\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003e\u0026delta;\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003eCTOD - Crack Tip Opening Displacement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003emm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u0026micro;m\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003emicrons\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003e\u0026micro;m\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 6.50096%;\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 24.6654%;\"\u003e\n \u003cp\u003e\u003cem\u003eVp\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51.8164%;\"\u003e\n \u003cp\u003edisplacement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 17.0172%;\"\u003e\n \u003cp\u003emm\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData Availability Statement\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data for this study are provide and accessible in the tables, pictures, plots, and figures. The authors are available for further inquiries.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGil M. Agag Jr. a, b, c,\u003cem\u003e\u003csup\u003e\u0026nbsp;d \u0026amp; e\u003c/sup\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003ePersia Ada N. de Yro \u003cem\u003e\u003csup\u003ea, f\u003c/sup\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eRocel D. Gualberto \u003cem\u003e\u003csup\u003ee\u003c/sup\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eDonnalyn Cabaces \u003cem\u003e\u003csup\u003ee\u003c/sup\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eClodualdo Aranas Jr. \u003cem\u003e\u003csup\u003ee\u003c/sup\u003e\u003c/em\u003e\u003c/p\u003e\n\u003col style=\"list-style-type: lower-alpha;\"\u003e\n \u003cli\u003e\u003cem\u003eConception or design of the work\u003c/em\u003e\u003c/li\u003e\n \u003cli\u003e\u003cem\u003eData collection\u003c/em\u003e\u003c/li\u003e\n \u003cli\u003e\u003cem\u003eData analysis and interpretation\u003c/em\u003e\u003c/li\u003e\n \u003cli\u003e\u003cem\u003eDrafting and revision of the article\u003c/em\u003e\u003c/li\u003e\n \u003cli\u003e\u003cem\u003eCritical review of the article\u003c/em\u003e\u003c/li\u003e\n \u003cli\u003e\u003cem\u003eFinal approval of the version to be published\u003c/em\u003e\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere is no available funding for this project.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no acknowledged competing financial interests or personal relationships that could have influenced the work presented in this study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBai Y and Jin WL (2015) Marine Structural Design. LNG Carrier. In: Marine Structural Design, 3\u003csup\u003erd\u003c/sup\u003e edn, Elsevier, London, UK, pp 957-977. doi: 10.1016/b978-0-08-099997-5.00004-6. \u003c/li\u003e\n\u003cli\u003eS\u0026aacute;nchez S, L\u0026oacute;pez-Guti\u0026eacute;rrez JS, Negro V, and Esteban MD (2009) Foundations in offshore wind farms: Evolution, characteristics and range of use. Analysis of main dimensional parameters in monopile foundations. Journal of Marine Science and Engineering vol. 7, no. 12. doi: 10.3390/JMSE7120441.\u003c/li\u003e\n\u003cli\u003eScherf I, Hansen T, and Sigurdsson G (2018) Safe operation of jacket platforms in a major oil field in the North Sea. In: Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE, \u003cbr\u003e Madrid, Spain, 17-22 June 2018 vol. 1. doi: 10.1115/OMAE2018-77526.\u003c/li\u003e\n\u003cli\u003eFajuyigbe A and Brennan F (2021) Fitness-for-purpose assessment of cracked offshore wind turbine monopile. Marine Structures, vol. 77. doi: 10.1016/j.marstruc.2021.102965.\u003c/li\u003e\n\u003cli\u003eMaljaars J, Pijpers R, and Slot H (2015) Load sequence effects in fatigue crack growth of thick-walled welded C-Mn steel members. International Journal of Fatigue, vol. 79. doi: 10.1016/j.ijfatigue.2015.04.021.\u003c/li\u003e\n\u003cli\u003eFondjo AA and Dzogbewu TC (2019) Assessment of stress raiser factor using finite element solvers. Univers. J. Mech. Eng., vol. 7, no. 6. doi: 10.13189/ujme.2019.070608.\u003c/li\u003e\n\u003cli\u003eGuest S, Dyck J, Egbewande A, MacKenzie AR, and Sadowski M (2016) Design of in-service repair welding procedures for operating pipelines: Critical assessment of variables affecting restraint level and heat-affected zone microstructures of vintage pipelines. In: Proceedings of the Biennial International Pipeline Conference, IPC, Sep 26-30, 2016, Alberta Canada, vol. 3. doi: 10.1115/IPC201664206.\u003c/li\u003e\n\u003cli\u003eGoli-Oglu EA and Filatov AN (2023) Fractographic Studies of Destruction Nature of Plate Steel S420MLO After Fatigue Tests CTOD. Steel Transl., vol. 53, no. 5. doi: 10.3103/S0967091223050054.\u003c/li\u003e\n\u003cli\u003eCoronado JJ and Cer\u0026oacute;n C (2010) Fracture mechanisms of CTOD samples of submerged and flux cored arc welding. Theor. Appl. Fract. Mech., vol. 53, no. 2. doi: 10.1016/j.tafmec.2010.03.008.\u003c/li\u003e\n\u003cli\u003eKitagawa Y and Kawasaki H (2013) Recent development of high-strength and tough welding consumables for offshore structures. R D Res. Dev. Kobe Steel Eng. Reports, vol. 63, no. 1.\u003c/li\u003e\n\u003cli\u003eSetiyanto NA, Oktadinata H, and Winarto W (2019) Effect of Nickel on the Microstructure, Hardness and Impact Toughness of SM570-TMC Weld Metals. 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World, vol. 54, no. 7\u0026ndash;8, 2010, doi: 10.1007/BF03263504.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"CTOD, FCAW, fracture toughness, mechanical properties, microscopy, Offshore jacket structure","lastPublishedDoi":"10.21203/rs.3.rs-7196752/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7196752/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eOffshore jackets are essential structures in the energy sector, including wind farms and oil and gas activities. The experiment involves welding a 72 mm K-bevel S355 KT-40 plate utilizing gas-shielded flux-cored arc welding (FCAW-GS) in a horizontal position. Welds are evaluated using microhardness, tensile, Charpy impact toughness at -40°C, crack tip opening displacement (CTOD) at 0°C, and microscopy, subsequently accompanied by statistical analysis and numerical modelling. The highest microhardness is 246 Hv5, meeting the maximum requisite of 325 Hv5, while the yield stress and tensile strength of the welds exceed those of the base metal, measured at 565 and 602 MPa, respectively. The minimum Charpy single value is 73.9 J, and the average value is 108 J, both exceeding the 40 J industry norm. Weld metals (WMs) at the weld centerline and the grain-coarsened heat-affected zones (GCHAZs) have minimal CTOD values of 0.28 mm and 0.36 mm, respectively, surpassing the requisite threshold of 0.15 mm. The microstructure of the GCHAZs has a grain size between 31.8 and 63.5 µm, hence improving corrosion resistance. A one-way ANOVA of the Charpy and microhardness has significant differences corresponding to measurement regions. Mesh and contour plots demonstrate a robust positive correlation among CTOD, load, and displacement. The quadratic equation modelling fracture lengths demonstrates a significant correlation coefficient of 74.7%, producing a parabola with its vertex at x, y (35.435385, 40.2809) mm, which defines optimal crack length. The welds surpass AWS D1.1 criteria, enhancing performance and prolonging structural integrity.\u003c/p\u003e","manuscriptTitle":"Experimental investigation of CTOD fracture toughness in FCAW-GS welds of offshore jacket structure","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-24 08:52:39","doi":"10.21203/rs.3.rs-7196752/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"866044cf-cda8-4948-9854-143e5e4fcf35","owner":[],"postedDate":"July 24th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":51999304,"name":"Materials Engineering"}],"tags":[],"updatedAt":"2025-07-24T08:52:39+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-24 08:52:39","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7196752","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7196752","identity":"rs-7196752","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}