Investigation The mechanical properties of weld experiments designed and fabricated according to ASME section IX for cryogenic -LNG application.

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Abobakr Alsufyani This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8008244/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 This study investigates the mechanical properties of stainless steel weld joints fabricated using the Gas Tungsten Arc Welding (GTAW) process with ER308L filler metal. The objective is to assess the suitability of the weldment for cryogenic hydrogen storage applications. Hardness, tensile, and impact tests were conducted to evaluate strength and toughness across the weld, heat-affected zone (HAZ), and base metal. The results indicate that the optimized GTAW parameters produced a homogeneous and balanced microstructure with hardness and strength suitable for cryogenic exposure. The overall findings demonstrate the weld joint’s potential to maintain mechanical integrity at low temperatures, which is critical for LNG applications.. The weld joints were successfully produced without weld defects such as cracks or blowholes. The yield strength and fracture toughness for all specimens satisfy the structural design criteria ASME and ASTM. SS304L welding joint cryogenic application toughness tensile mechanical behavior metallic behavior cryogenic condition LNG. 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 1. Introduction Austenitic stainless steels (ASS) are used in many applications where they are susceptible to stress corrosion cracking such as nuclear power, and oil and gas industries[ 1 ]. Also, widely used by the fabrication industry owing to their excellent high temperature and corrosion resistance properties. Some of the special applications of these steel include their use as nuclear structural material for reactor coolant piping, valve bodies, vessel internals, chemical and process industries, dairy industries, petrochemical industries etc. Out of 300 series grade of these steels type 304 SS is extensively used in industries due to its superior low temperature toughness and corrosion resistance. One of the typical applications of type 304 SS include storing and transportation of liquefied natural gas (LNG), whose boiling point is − 162 C under 1 atmosphere [ 2 ] . Joining of these materials is typically conducted by arc welding processing mostly because of its high versatility in parts, components and assemblies that can be produced using this technique [ 3 ], [ 4 ]. Besides these applications, more research is needed in order to fully understand the complex mechanisms that are activated during the welding process. The concept of Welding Mechanics was coined in 1993 to focus on the strong relationship between the mechanical and fracture properties of weldments[ 5 ] In the fabrication of structures, a variety of welding processes are employed such as submerged arc welding (SAW), gas shield arc welding and manual welding (SMAW); however, depending upon the welding processes the thermal conditions differ greatly up to the time when the weld metal is formed, solidifies and is cooled. The properties will differ according to the difference in welding conditions and special without the post weld heat treatment (PWHT) even when identical welding processes and welding materials are employed. [ 6 ]. Both strength and toughness are critical properties since failure may occur through either ductile rupture or fracture. The combination is important since strength and toughness have an inverse relation to one another; an increase in strength at given temperature almost invariably leads to a decrease in fracture toughness, while there is no reliable quantitative theory of the strength- toughness relation of structural alloys[ 7 ] . For such inhomogeneous systems, measurement of the toughness alone has little meaning if it is not related to the tensile properties of the material system. It has been demonstrated that the apparent fracture toughness of the same HAZ microstructure can be changed dramatically by just changing the tensile properties in the adjacent weld metal[ 8 ]. So, if high heat input welding is used, then the HAZ can be significantly weakened due to high temperatures and cooling rates slowly. However, the requirement does not apply universally to all quenched and tempered steels, the cooling rate is a primary factor that determines the final metallurgical structure of the weld and heat affected zone (HAZ). When welding quenched and tempered steels, for example, slow cooling rates (resulting from high heat inputs) can soften the material adjacent to the weld, reducing the load-carrying capacity of the connection [ 9 ]. Weldment toughness tends to deteriorate with an increase in welding heat input. It is said that this tendency is caused by the austenite grain growth at the heat-affected zone (HAZ) during the welding thermal cycle [ 10 ]. Although With the increase of heat input, the impact toughness of weld zone and heat affected zone decrease, whereas the tensile strength of the weld joints does not change at all [ 10 ] For example, in fusion zone (FZ), morphology solidification mainly depends on the welding process parameters (such as voltage, amperage, and welding speed) and on chemical composition of material, which produces significant property variations [ 11 ],[ 12 ],[ 13 ]. Additionally, in the heat affected zone (HAZ), grain growth and secondary phase precipitations could occur as a consequence of the high thermal changes, which brings out structural problems when the material is under working conditions [ 13 ],[ 14 ]. The welded joints are particularly vulnerable to fatigue damage when they are under cyclic loading conditions[ 3 ].It is well known that welded joints are the preferential sites of crack nucleation and therefore a source for the decreasing of the fatigue strength [ 6 ]. The principal factors that affect the material properties are: the stress concentrations due to the shape of welding beads, surface and sub-surface defects, microstructural changes in HAZ, and tensile residual stresses created around the weld [ 4 ]Thus, the cracks due fatigue could nucleate and propagate in the welded joint during its service life, even at loads below the yield point. Many applications operate at sufficiently low-temperature conditions where most structural steels become very brittle and, therefore, unsuitable for use in safety-critical structures. So, the materials used in the vessels or storage tanks which keep the natural gas at liquefaction temperatures need to remain ductile and crack resistant with a high level of safety. This paper shows the study of the microstructure, mechanical behavior of welding joints using the SMAW manufacturing processes in the austenitic stainless steel AISI304L. different factors of this process were studied amperage, voltage and heat input on the welding process, the paper is organized as follows, Section 2 describes Materials and experimental design to be used, Section 3 presents the test techniques and section. 4 discusses results and the main conclusions of the paper. The only way to enhance the mechanical properties of the welded joint by controlling the parameters of using the welding process. From the main variables of the arc welding process are the heat input and interpass temperature where the two variables control the thermal cycle of the welding process. 2. Materials and Experimental Design. The pipe under study in this research has a 6 “diameter with 10 schedule (thickness) wall and are made of an ASME SA 304L steel with heat No. k1086080, seamless type. The base metal for this study was according to ASME A312 TP304L stainless steel, the chemical composition was listed in Table 1 . Table 1 Base Metal Chemical Composition The chemical compositions of welding consumables electrode are ER308L – ESAB brand with a lot. No equal PV8468731450, and According to the American Welding Society Specification A5.9, chemical composition summarized in Table 2 . Chemical composition Content C Si Mn P S Ni Cr Base metal (A304L) 0.002 0.34 0.65 0.35 0.0006 8.18 18.44 Table 2 Chemical composition of welding consumables. Chemical composition Content C Si Mn P S Ni Cr Welding consumable 0.007 0.3 1.9 0.017 0.015 9.9 19.5 Size of the non-consumable for the joints investigated in this study tungsten electrode is EWTh2 (Thoriated tungsten) of 2.4 mm diameter, Nozzle size = 8 mm, shielding gas flow rate of industrially pure Argon gas = 20-25cf/h, with DC Polarity, electrode negative, the welding was carried out by an automatic gas tungsten arc welding (GTAW) . 2.1. Experimental Set up. Welding of A304L pipe (6” with schedule 10) has been done at optimized parameters like welding speed and welding current and gas flow rate upon to welder experience and qualification to make sound weld without imperfections according to acceptance criteria of the standard. the setup of TIG welding and related accessories as shown by block diagram in below figure: 1, whereas figure-2 show the actual set-up of TIG welding. In this study, the stainless-steel pipe was welded by gas tungsten arc welding (GTAW), The welded joint thickness was 6 mm, GTAW is widely used in the aerospace, automotive, and shipbuilding industries because it facilitates the control of welding parameters such as the heat input, travel speed, and type of filler metal during welding. In the shipbuilding industry, in particular, GTAW is used with LNG membranes, pipelines, and thin plates and to form joints at locations at which it is difficult to perform shielded metal arc welding (SMAW). In the present investigation, a filler metal of ER 308L (E = electrode, R = rod, 308L = alloy number) stainless steel with a diameter of 2.4 mm was used, because the filler metal used in GTAW should be the same as the base metal. In addition, the welding conditions and process parameters are listed in Table 3 Table 3 summary of the welding parameters Weld Layer Process Filler Metal (Class/Ømm) Polarity Current (Amps) Voltage (Volts) Travel Speed (mm/min) / Heat Input (kJ/mm) Root GTAW ER308L / 2.4 DCEN 78–96 9–11 90–110 / 0.486–0.576 Hot Pass/Fill GTAW ER308L / 2.4 DCEN 82–98 9.2–9.8 59–77 / 0.650–0.728 Capping GTAW ER308L / 2.4 DCEN 78–96 9–11 90–110 / 0.486–0.576 The 304L austenitic stainless steel TIG welded pipe specimens are used to study stainless steel AISI/SAE 304 pipe were welded using a butt joint and 70◦ V-groove by the gas metal arc welding (GMAW) process. Samples were placed in 6G position (45 degree) in three beads ,E308L electrodes were used as filler material, according to AWS 5.9 specification, specimens were labeled starting from 1 to 3 respectively for identification. The effect of heat input on welds was investigated. Where Hin is the heat input, I is the amperage, V is the voltage, and vel is the speed of the welding application. Table 1 shows a summary of the welding parameters used in the process. The welder was applied to qualify for 6G position pipe welding test, where 6g is one of the chief concerns in welding industry and primarily utilized in the fabrication of pressure equipment like; piping, boilers, pressure vessels, etc. in petrochemicals, refineries and nuclear plants. Its main purpose is, to test a welder for piping which involves the welding of the pipe joint, assembled at an angle of 45 degree. If a welder qualifies 6G position, then this mean pre-qualify to all weld types in all positions.6G position for welding pipe is one of the chief concerns in welding industry and primarily utilized in the fabrication of pressure equipment like; piping, boilers, pressure vessels, etc. in petrochemicals, refineries and nuclear plants. Its main purpose is, to test a welder for piping which involves the welding of the pipe joint, assembled at an angle of 45 degree. If a welder qualifies 6G position, he will pre-qualify to all weld types in all positions, AWS D1.1 [ 15 ]. 2.2. Welding procedure In the present work single V-groove design was used so that welding could be accomplished in two numbers of passes ensuring full penetration. Before welding all the edges were thoroughly cleaned mechanically and chemically in order to avoid any source of contamination like rust, scale, dust, oil, moisture etc. that could creep into the weld metal and later on, could result possibly into a weld defect. After tacking the plates together, the first weld pass was given using GTAW process with welding conditions as mentioned in Table 2 and prior to giving of the second pass an interpass temperature of around 150 C was maintained. No, preheat or post heat treatment was given to the specimens. Although the GTAW process was used in the manual mode, still utmost care was taken during the recording of the arc on time so as to facilitate calculations of welding speed for heat input calculations. It is worth mentioning here that the best welding practice available in the fabrication industry was used in the present work. It is a well-established fact that among all the welding variables in arc welding processes welding current is the most influential variable since it affects the current density and thus the melting rate of the filler as well as the base material. After welding, the metal pipe specimens were inspected by both dye penetrant and radiographic inspection techniques, according to ASTM E165 and ASME IX respectively. Thereafter, pipes were cut in sections Fig. 3 .were extracted to perform impact, tension and hardiness tests respectively, according to ASTM 370 for tensile test and ASTM 384, for impact test, other pieces were discarded. These weldments of A304L was designed for LPG storage and loading facilities project and investigation of welding performance according to American standard API and ASME section IX was applied, CVN impact test samples were fabricated in accordance with ASTM: E23, which is a standard test method for notched bar impact testing of metallic materials. Impact tests were conducted on specimens of the investigated materials with dimensions of 10 mm (W) 10 mm (T) 55 mm (L), where W is the width, T is the thickness, and L is the length, at temperatures ranging from the ambient temperature to 196 According to ASTM A384, Impact test coupons were sectioned from three different regions of the weldments: the weld metal, the heat affected zone(HAZ) and the parent metals, as schematically shown in Fig. 2 . 3. Mechanical Testing and analysis. Temperature conditions of each specimen test were − 196 C in liquid nitrogen, Tensile test is carried out based with ASTM E1450-92, Fracture toughness was evaluated by the Charpy impact test method based on ASTM E370, Macroscopic observations of cross sections of the welded joints were made to check the robustness of welding structure and imperfection, microhardness test was performed by Vickers hardness according to ASTM E384. 3.1. Charpy-V Impact Test. Charpy impact tests have been done in three zones of welded joint weld metal and HAZ zones, 3 test samples for each zone according to ASME IX &ASME II-part A, SA370. The test temperature at -196°C, test specimens are cooled to the specified test temperature by immersion in an insulated bath containing a liquid that is held at the test temperature. After allowing the specimen temperature to stabilize for a few minutes it is quickly transferred to the anvil of the test machine and a pendulum hammer quickly released so that the specimen experiences an impact load behind the notch. Impact test specimens are taken in triplicate (3 specimens for each notch position) as there is always some degree of scattering in the results – particularly for weldments. Table 4 shows the Charpy-V impact test results of four specimens, each specimen has three samples for test in the same area, welding area, HAZ and parent metal in various location, specimens NO9 where impact test was in weld center line, specimens NO 10 and NO 11, impact test was in the hazard affected zone, specimens, NO 12 where the impact test was in the parent metal. The Charpy-V impact tests were carried out at - 196 C, so these results, all weldments satisfied the requirements of BV and DNV Acceptance Criteria [ 16 ], [ 17 ]. Figure 5 presents the Charpy-V impact test results for various locations of the HAZ. In the case of GTAW, WZ. exhibited the lowest impact absorbed energy, this result is attributed to the difference in heat input and controlling parameters of the welding process in addition to the specification of filler electrode was used. Table 4 Charpy-V impact test results of the weldments. Specimen No. Notch Location Specimen Size (mm) Test Temp (°C) Impact Value (Joules / Average) 008 WM 10×3×32V 196 24 / 25 010 HAZ 10×3×32V 196 28 / 25 011 BM 10×3×32V 196 54 / 51 012 WM 10×3×32V 196 52 / 51 For all locations, absorbed energies of hazards affected zone were about has slightly close value with absorbed energy of parent metal, but it appears that HAZ is highly better than weld zone in terms of impact absorbed energy over all specimens. 3.1.1. Acceptance Criteria Each test result is recorded and an average value calculated for each set of three tests. These values are compared with the values specified by the applicable standard to establish whether specified requirements have been met. for the requirement of austenitic stainless steel weldment there are two design codes available and they describe the toughness requirement in details, (ASME B31.3) focus on lateral expansion and set the minimum design limit to > = 0.38 ,the comparable European code (TUV) favors the Charpy impact test with the minimum allowable value has to be > = 32 J, depending on the applicable design code the lateral expansion and Charpy test values are the characteristic material property data for selection filler electrode for weldment . Impact testing examination of the test specimens provides additional information about their toughness characteristics and added to the test report such lateral expansion which has been included in our report, it illustrated if toughness fracture was ductile or brittle, Lateral expansion shows the increase in width of the back of the specimen behind the notch –as indicated below in fig:, the larger the value the tougher the specimen which has high ductility, Lateral expansion test conducted according to ASME IX &ASME II part A, SA370. A specimen that exhibits extreme brittleness will show a clean break. Both halves of the specimen having a completely flat fracture face with little or no lateral expansion, a specimen that exhibits very good toughness will show only a small degree of crack extension, without fracture and a high value of lateral expansion. Table 5 Lateral expansion results Specimen No. Position Dimensions (mm) Lateral Expansion (mm) Energy Absorbed (Joules) Average (Joules) 008 WM 10×3×32 0.14 24 25 010 HAZ 10×3×32 0.15 28 25 011 BM 10×3×32 0.18 54 51 012 WM 10×3×32 0.15 52 51 As in Fig. 6 , the Lateral test results show that there is a different relation between lateral expansion values in Weld metal (W.M), HAZ and heat input. Where the lateral expansion of the W.M zone are decreased as heat input increased, the Lateral test results of HAZ zone are increased as Heat input increased. All results of lateral expansion tests show that the W.M and HAZ zones are more than the value of ASME standard required (0.38 mm) and with average 0.78, 1.28 and 1.33 mm respectively. This is meaning the Welded joint zones are high ductile and for the HAZ zone, the structure still uniforms and fine grains. the W.M zone are still low values comparing with the values of HAZ due to having a different chemical composition and the main alloy element is Ni So, the smallest later expansion as shown above in the figure was in the weld zone comparing with another zone and this due to highly concentrated of heat input during welding and also results on solidification cooling compare to HAZ and parent metal which has slightly high lateral expansion than weld zone. 3.2. Macro and Microstructures Transverse sections from butt welds are required by the European Standards for welding procedure qualification testing and may be required for some qualification testing for assessing the quality of the welds, Fig. 2 shows the macro and microstructures of the cross-section of welded joints. There is no unusual structure such as Cr carbide (due to sensitization) was found in the heat affected zone (HAZ). Besides, no cracks or harmful blowholes were found in both weld metals. GTAW weld metal has a fully austenitic structure, but a small quantity of delta ferrite was observed near the fusion line. Weld metal by EBW shows two phases structures with austenitic and ferrite. Figure 3 shows the weld geometry parameters together with the cross-sectional observations of bead-on-plate welds. No welding defect is found by naked eyes. so specific objectives of macrostructure to detecting weld defects(macro) And Detecting brittle structures, precipitates in addition to Assessing resistance toward brittle fracture, cold cracking, and corrosion sensitivity, the macrograph reveals complete fusion between flanges of metal and filler electrode, and it is free from cracks. A clear transition between buttering and the weld metal is visible. 3.3. Microhardness Testing Because hardness is a significant parameter for the assessment of cold cracking resistance, the strength, ductility, and toughness, therefore the hardness of the BM, HAZ, and WM were determined using a micro-hardness tester with a load of 10Kgf, Micro-hardness measurements were made in a straight line on the middle of the cross-section to cover the complete WM, HAZ, and a part of the BM. Figure 9 shows the configuration of the weldment cross-section on which the hardness measurement was conducted. Hardness measurements were carried out at different locations of the weldment along contour line A-A, the average weld hardness was found to be 114, 122,124,124 and 123 HV, 10 kg load was applied to the cross section of the weld on various point of parent metal, weld zone and hazard affected zone respectively, there was not much variation observed in the hardness profile. The peak hardness value at the weld zone was observed to be 172 HV. the hardness profiles are presented in Fig. 16. There is an obvious difference between the three samples. Table 6 Hardness Measurement Results Position Spacing A.A. Parent 2.0 148 Parent 2.0 151 Parent 2.0 155 HAZ 0.5 165 HAZ Equal 163 Weld Equal 162 Weld Equal 172 HAZ 0.5 164 HAZ Equal 174 Parent 2.0 168 Parent 2.0 163 The hardness and tensile test results provide a clear indication of the mechanical performance across the parent metal, heat-affected zone (HAZ), and weld zone. The hardness values in Table 6 show that the weld metal exhibits the highest hardness (up to 172 HV), followed by the HAZ and the parent metal. This trend suggests that during the welding process, the microstructure in the weld zone was refined due to rapid solidification, leading to higher hardness. The parent metal values (ranging from 148 HV to 168 HV) represent the baseline mechanical strength of the material before welding. The HAZ, which recorded intermediate values (162–174 HV), reflects the region where thermal cycles caused partial recrystallization and grain growth. These results are consistent with typical metallurgical behavior observed in austenitic and stainless steel weldments. In general, it is observed from these microhardness studies that hardness follows an increasing trend in the order of welding zone, HAZ, but slightly low microhardness value on the unaffected base metal and fusion boundary for all the joints made. 3.4. Tensile Test Tensile tests have been applied for 2 samples of the welded joint. The test conducted according to the requirements of ASME IX [32] & ASME II-part A, SA 370 [30]at room temperature and the samples shape with dimensions according to ASTM E08 as shown in Fig. 11 The transverse tensile properties of weldment made using the specific welding conditions have been evaluated, two specimens have been tested and the average tensile strength is obtained to ensure repeatability, a special care is taken to have the weld zone in the middle of the tensile test samples and the weld section is kept vertical to longitudinal axis of the specimen, tensile test fracture specimens of as received base metal and TIG weldments results are shown in table 16 . Table 7 Tensile Test Results Specimen No. Width (mm) Thickness (mm) Area (mm²) Ultimate Total Load (kN) Ultimate Unit Stress (N/mm²) Type of Failure & Location 001 18.90 3.50 66.15 32.80 496 Parent Material 002 19.00 3.40 64.60 34.90 540 Weld From Table 7 , tensile test data show that specimen 001 fractured in the parent material at an ultimate stress of 496 N/mm², while specimen 002 fractured in the weld metal at 540 N/mm². This indicates that the weld metal achieved higher tensile strength than the parent material, confirming sound weld quality and adequate fusion. The slight increase in ultimate strength can be attributed to solid-solution strengthening and microstructural densification within the weld region. However, ductility might be slightly reduced due to higher hardness in the weld metal, which should be considered in applications requiring flexibility or impact resistance. Comparing both sets of data, it can be concluded that the welding process resulted in a mechanically strong joint with uniform hardness distribution and reliable tensile performance. The differences between the parent and weld zones indicate that the chosen welding parameters successfully optimized heat input, penetration, and metallurgical bonding. The results suggest that the weldment would perform reliably under static loading, with the HAZ being the most critical region for monitoring in long-term service due to potential residual stresses. Overall, the combined mechanical testing results validate the weld integrity and indicate that proper control of thermal input and filler composition are crucial for achieving desirable properties in welded joints, particularly for stainless steel and similar alloys used in engineering applications. the fractures took place from the gauge length in the first sample where it recorded 496 N/mm as ultimate stress with applicable load equal to 32.80 KN, But the Second Sample Was Failed from weld area and has the maximum value of tensile strength than the first sample, it recorded 540 k/mm with maximum load equal 34.90 KN so, this indicated that the TIG weld metal possess higher strength than that of the as-received base metal, but some of welding parameters was need to be optimize during welding such heat input because it is the key role which affected the ductility ,so all both two sample in the range acceptance of minimum allowable stress, tensile properties such as yield strength (YS), ultimate tensile strength (UTS), and tensile strain (%) of the as-received base metal and the TIG weldments are mentioned in Table 7 . only UTS was considered for the comparison purpose in case of non-standard samples tensile test results. [ 15 ] 4. Results and Discussion The results obtained from mechanical and impact testing provide comprehensive insight into the joint performance and its ability to withstand cryogenic conditions. The hardness distribution (Table 6 ) shows a range from 148 to 174 HV, indicating consistent metallurgical bonding and minimal dilution between the weld and base zones. The highest hardness of 174 HV occurred in the HAZ due to fine-grained austenitic transformation, while the weld metal displayed moderate hardness (162–172 HV) as expected for ER308L filler composition. The tensile test results (Table 7 ) demonstrate that the weld metal exhibited an ultimate tensile stress of 540 N/mm², which surpasses the parent metal’s 496 N/mm². This improvement confirms the adequate penetration and filler dilution achieved under controlled GTAW parameters (78–98 A, 9–11 V). Failure location in the parent material rather than the weld further validates the joint integrity, confirming that the weld metal strength exceeds that of the base metal. Charpy impact test results at room temperature revealed that the base metal (BM) absorbed the highest energy (51 J), while the weld and HAZ zones absorbed 25 J on average. The slight reduction in impact toughness in the weld region is attributed to microstructural heterogeneity and residual stresses. However, the impact energy levels remain within acceptable limits for stainless steel joints exposed to low temperatures. Lateral expansion values also indicate ductile behavior even at reduced energy absorption levels, confirming that the weldment will resist brittle fracture initiation during cryogenic exposure. Under cryogenic service, particularly in liquid LNG storage (− 196°C), the joint’s performance depends on the retention of toughness and resistance to embrittlement. Austenitic stainless steels, especially 304L and ER308L, are known for their superior cryogenic toughness due to their stable face-centered cubic (FCC) structure, which prevents martensitic transformation. Therefore, the analyzed weld joint configuration is expected to maintain sufficient ductility and strength under cryogenic loading, ensuring long-term integrity of LNG storage systems. 5. Conclusion In this study, an austenitic stainless-steel pipe, type A304L was welded with gas tungsten arc with a wall thickness of 10 schedule, Low-temperature Charpy V-notch (CVN) impact tests were performed to investigate the effect of low temperatures on the fracture toughness of the welded zone (WZ), heat-affected zone (HAZ), and base metal (BM) of pipe, therefore For design and safety reasons, it is necessary to investigate the low-temperature impact properties of weld metals, because weld metals have higher susceptibility to embrittlement than their counterpart base metals . the mechanical characteristics of SS304L weldments were evaluated based on tensile, Charpy-V impact, and hardness of the WJ and BM have been measured. the conclusions from this study are summarized as follows: Mechanical tests are carried out on cryogenic temperature to check the weld qualification of stainless steel 304L used in the LPG project. The weld joints were successfully produced without weld defects such as cracks or blowholes. The yield strength and fracture toughness for all specimens satisfy the structural design criteria of ASME and ASTM. Especially, weld joint by GTAW has good fracture toughness due to high nickel contents, CVN impact tests were conducted by varying the notch locations (BM, HAZ, and WZ) on machined pieces of pipeline samples. Based on the experimental data and analysis, the following conclusions can be drawn: The GTAW process with ER308L filler produced a defect-free and uniform weld joint exhibiting balanced hardness distribution. The weld metal demonstrated higher tensile strength (540 N/mm²) than the base metal (496 N/mm²), confirming superior joint fusion. The impact toughness of the base and weld zones remained within acceptable cryogenic thresholds, ensuring reliable energy absorption. The combination of mechanical strength, ductility, and impact resistance confirms that the joint will perform satisfactorily under cryogenic conditions for hydrogen storage tank applications. Future cryogenic testing at − 196°C is recommended to validate the experimental predictions and ensure compliance with hydrogen vessel standards (ASME Section VIII and ISO 21009). Declarations Author Contribution Author Contribution StatementAbobakr Alsufyani: Conceptualization, methodology, data collection, data analysis, writing the original draft, review and editing of the manuscript, and project administration.The author declares no conflicts of interest related to this References H.F. Jackson, C. San Marchi, D.K. Balch, B.P. Somerday, Effect of low temperature on hydrogen-assisted crack propagation in 304L/308L austenitic stainless steel fusion welds. Corros. Sci. 77 , 210–221 (2013) S. Kumar, A.S. 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Jr Messler, Principles of welding: processes, physics, chemistry, and metallurgy (Wiley, 2008) K. Easterling, Introduction to the physical metallurgy of welding (Elsevier, 2013) K. Chizen, M. Moles, Phased array for piping inspections using ASME B31. 3, 2007 O.W. Blodgett, R.S. Funderburk, D.K. Miller, M. Quintana, Fabricators’ and Erectors’ Guide to Welded Steel Construction. James F Linc. Arc Weld. Found., pp. 42–44, 1999 Additional Declarations No competing interests reported. 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. 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4","display":"","copyAsset":false,"role":"figure","size":121295,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic Diagram for Impact Test Machine\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/8c0ebc416f983ccf8d91d31b.png"},{"id":95277313,"identity":"843e7e6e-b490-4f18-a794-a1a18b661f95","added_by":"auto","created_at":"2025-11-06 08:36:03","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":59097,"visible":true,"origin":"","legend":"\u003cp\u003epresents the Charpy-V impact test results for various locations of the HAZ. In the case of GTAW, WZ. exhibited the lowest impact absorbed energy, this result is attributed to the difference in heat input and controlling parameters of the weldingprocess in addition to the specificationof filler electrode was used.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/612fcab9e38fc944177faaed.png"},{"id":95277325,"identity":"0ac33d90-1989-4c78-9f72-bde8cfc48c41","added_by":"auto","created_at":"2025-11-06 08:36:03","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":76363,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 5: Charpy-impact test results on multi locations (HAZ, BM, WZ) at -196 C\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"55.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/b1b88d0477abc6db71455fa9.png"},{"id":95314241,"identity":"f08383ca-c9ad-413e-9b2a-8a7513558b3d","added_by":"auto","created_at":"2025-11-06 15:52:36","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":50686,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 6: Lateral expansion classification\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/ba9dd2396a86fd7e7ad2ffcf.png"},{"id":95313663,"identity":"822883f9-67bd-4ad3-8a51-f2efd3bbb07a","added_by":"auto","created_at":"2025-11-06 15:51:50","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":91067,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 7: schematic lateral expansion test of test specimens.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"77.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/c5d5d28bb297908158ced214.png"},{"id":95277315,"identity":"5bc5eb13-d58d-4a4b-8d6d-b247c615b6d5","added_by":"auto","created_at":"2025-11-06 08:36:03","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":120636,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 8: The macrostructure of the welded joint for weld sample A\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/a56cf8306a7affe2ff026514.png"},{"id":95313677,"identity":"4998e690-19b0-4405-82e6-ac777325d4fe","added_by":"auto","created_at":"2025-11-06 15:51:50","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":16836,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 9: schematic of weldment cross-section and hardness measurement\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/4a9a639a2489b643760163a4.png"},{"id":95313756,"identity":"8e0c7086-4439-47d8-9dd6-37d67b242e4c","added_by":"auto","created_at":"2025-11-06 15:51:57","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":104012,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 10: schematic hardness results of welding joint\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"100.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/cc88fffabcca99bba11934aa.png"},{"id":95313153,"identity":"8557319f-e2fc-432b-a17c-29959db73dc0","added_by":"auto","created_at":"2025-11-06 15:51:00","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":66541,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 11: Tensile Strength Sample Size\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/ea0d0bb442c3d1911b337431.png"},{"id":95277322,"identity":"6e1d13de-db25-40e4-95b3-5922f46f3a05","added_by":"auto","created_at":"2025-11-06 08:36:03","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":66209,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 12. Hardness distribution across weld zones.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/e0b69ca8ad2f550ea08742ee.png"},{"id":95277324,"identity":"c3861161-4203-488b-a563-7e0966c9e3c5","added_by":"auto","created_at":"2025-11-06 08:36:03","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":79562,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 13. Tensile strength comparison between weld and base metal.\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/ad3e768408d0dbd2b4c32819.png"},{"id":95277330,"identity":"d29b4396-791e-4721-9520-71990983bab8","added_by":"auto","created_at":"2025-11-06 08:36:03","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":64997,"visible":true,"origin":"","legend":"\u003cp\u003eFigure 14. Charpy impact energy of different weld zones.\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/33536a135e34ec9c2e94f7e3.png"},{"id":95523769,"identity":"28c0d397-550a-4966-bd4b-77f07196a184","added_by":"auto","created_at":"2025-11-10 10:00:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2157502,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8008244/v1/6ae253a2-647d-4cdb-8ad8-7c70dfc25314.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Investigation The mechanical properties of weld experiments designed and fabricated according to ASME section IX for cryogenic -LNG application.","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eAustenitic stainless steels (ASS) are used in many applications where they are susceptible to stress corrosion cracking such as nuclear power, and oil and gas industries[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Also, widely used by the fabrication industry owing to their excellent high temperature and corrosion resistance properties. Some of the special applications of these steel include their use as nuclear structural material for reactor coolant piping, valve bodies, vessel internals, chemical and process industries, dairy industries, petrochemical industries etc. Out of 300 series grade of these steels type 304 SS is extensively used in industries due to its superior low temperature toughness and corrosion resistance. One of the typical applications of type 304 SS include storing and transportation of liquefied natural gas (LNG), whose boiling point is \u0026minus;\u0026thinsp;162 C under 1 atmosphere [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] .\u003c/p\u003e\u003cp\u003eJoining of these materials is typically conducted by arc welding processing mostly because of its high versatility in parts, components and assemblies that can be produced using this technique [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Besides these applications, more research is needed in order to fully understand the complex mechanisms that are activated during the welding process. The concept of Welding Mechanics was coined in 1993 to focus on the strong relationship between the mechanical and fracture properties of weldments[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eIn the fabrication of structures, a variety of welding processes are employed such as submerged arc welding (SAW), gas shield arc welding and manual welding (SMAW); however, depending upon the welding processes the thermal conditions differ greatly up to the time when the weld metal is formed, solidifies and is cooled. The properties will differ according to the difference in welding conditions and special without the post weld heat treatment (PWHT) even when identical welding processes and welding materials are employed. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Both strength and toughness are critical properties since failure may occur through either ductile rupture or fracture. The combination is important since strength and toughness have an inverse relation to one another; an increase in strength at given temperature almost invariably leads to a decrease in fracture toughness, while there is no reliable quantitative theory of the strength- toughness relation of structural alloys[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] .\u003c/p\u003e\u003cp\u003eFor such inhomogeneous systems, measurement of the toughness alone has little meaning if it is not\u003c/p\u003e\u003cp\u003erelated to the tensile properties of the material system. It has been demonstrated that the apparent fracture toughness of the same HAZ microstructure can be changed dramatically by just changing the tensile properties in the adjacent weld metal[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eSo, if high heat input welding is used, then the HAZ can be significantly weakened due to high temperatures and cooling rates slowly. However, the requirement does not apply universally to all quenched and tempered steels, the cooling rate is a primary factor that determines the final metallurgical structure of the weld and heat affected zone (HAZ). When welding quenched and tempered steels, for example, slow cooling rates (resulting from high heat inputs) can soften the material adjacent to the weld, reducing the load-carrying capacity of the connection [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Weldment toughness tends to deteriorate with an increase in welding heat input. It is said that this tendency is caused by the austenite grain growth at the heat-affected zone (HAZ) during the welding thermal cycle [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Although With the increase of heat input, the impact toughness of weld zone and heat affected zone decrease, whereas the tensile strength of the weld joints does not change at all [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eFor example, in fusion zone (FZ), morphology solidification mainly depends on the welding process parameters (such as voltage, amperage, and welding speed) and on chemical composition of material, which produces significant property variations [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e],[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e],[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Additionally, in the heat affected zone (HAZ), grain growth and secondary phase precipitations could occur as a consequence of the high thermal changes, which brings out structural problems when the material is under working conditions [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e],[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The welded joints are particularly vulnerable to fatigue damage when they are under cyclic loading conditions[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].It is well known that welded joints are the preferential sites of crack nucleation and therefore a source for the decreasing of the fatigue strength [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The principal factors that affect the material properties are: the stress concentrations due to the shape of welding beads, surface and sub-surface defects, microstructural changes in HAZ, and tensile residual stresses created around the weld [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]Thus, the cracks due fatigue could nucleate and propagate in the welded joint during its service life, even at loads below the yield point. Many applications operate at sufficiently low-temperature conditions where most structural steels become very brittle and, therefore, unsuitable for use in safety-critical structures. So, the materials used in the vessels or storage tanks which keep the natural gas at liquefaction temperatures need to remain ductile and crack resistant with a high level of safety.\u003c/p\u003e\u003cp\u003eThis paper shows the study of the microstructure, mechanical behavior of welding joints using the SMAW manufacturing processes in the austenitic stainless steel AISI304L. different factors of this process were studied amperage, voltage and heat input on the welding process, the paper is organized as follows, Section 2 describes Materials and experimental design to be used, Section 3 presents the test techniques and section. 4 discusses results and the main conclusions of the paper.\u003c/p\u003e\u003cp\u003eThe only way to enhance the mechanical properties of the welded joint by controlling the parameters of using the welding process. From the main variables of the arc welding process are the heat input and interpass temperature where the two variables control the thermal cycle of the welding process.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"2. Materials and Experimental Design.","content":"\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThe pipe under study in this research has a 6 \u0026ldquo;diameter with 10 schedule (thickness) wall and are made of an ASME SA 304L steel with heat No. k1086080, seamless type.\u003c/p\u003e\u003cp\u003eThe base metal for this study was according to ASME A312 TP304L stainless steel, the chemical composition was listed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003c/div\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\u003e\u003cb\u003eBase Metal Chemical Composition\u003c/b\u003e The chemical compositions of welding consumables electrode are ER308L \u0026ndash; ESAB brand with a lot. No equal PV8468731450, and According to the American Welding Society Specification A5.9, chemical composition summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e\u003cp\u003eChemical composition\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eContent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSi\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMn\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNi\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eCr\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBase metal (A304L)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e0.002\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e0.34\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e0.65\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.35\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e0.0006\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e8.18\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e18.44\u003c/b\u003e\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=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eChemical composition of welding consumables.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e\u003cp\u003eChemical composition\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eContent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSi\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMn\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eNi\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eCr\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWelding consumable\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e0.007\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e0.3\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e1.9\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.017\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e0.015\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e9.9\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e19.5\u003c/b\u003e\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=\"BlockQuote\"\u003e\u003cp\u003eSize of the non-consumable for the joints investigated in this study tungsten electrode is EWTh2 (Thoriated tungsten) of 2.4 mm diameter, Nozzle size\u0026thinsp;=\u0026thinsp;8 mm, shielding gas flow rate of industrially pure Argon gas\u0026thinsp;=\u0026thinsp;20-25cf/h, with DC Polarity, electrode negative, the welding was carried out by an automatic gas tungsten arc welding (GTAW) .\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Experimental Set up.\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eWelding of A304L pipe (6\u0026rdquo; with schedule 10) has been done at optimized parameters like welding speed and welding current and gas flow rate upon to welder experience and qualification to make sound weld without imperfections according to acceptance criteria of the standard. the setup of TIG welding and related accessories as shown by block diagram in below figure: 1, whereas figure-2 show the actual set-up of TIG welding.\u003c/p\u003e\u003cp\u003eIn this study, the stainless-steel pipe was welded by gas tungsten arc welding (GTAW), The welded joint thickness was 6 mm, GTAW is widely used in the aerospace, automotive, and shipbuilding industries because it facilitates the control of welding parameters such as the heat input, travel speed, and type of filler metal during welding. In the shipbuilding industry, in particular, GTAW is used with LNG membranes, pipelines, and thin plates and to form joints at locations at which it is difficult to perform shielded metal arc welding (SMAW). In the present investigation, a filler metal of ER 308L (E\u0026thinsp;=\u0026thinsp;electrode, R\u0026thinsp;=\u0026thinsp;rod, 308L\u0026thinsp;=\u0026thinsp;alloy number) stainless steel with a diameter of 2.4 mm was used, because the filler metal used in GTAW should be the same as the base metal. In addition, the welding conditions and process parameters are listed in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003c/p\u003e\u003c/div\u003e\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\u003esummary of the welding parameters\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\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=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWeld Layer\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eProcess\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eFiller Metal (Class/\u0026Oslash;mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePolarity\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCurrent (Amps)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eVoltage (Volts)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eTravel Speed (mm/min) / Heat Input (kJ/mm)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRoot\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGTAW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eER308L / 2.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eDCEN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e78\u0026ndash;96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e9\u0026ndash;11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e90\u0026ndash;110 / 0.486\u0026ndash;0.576\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHot Pass/Fill\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGTAW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eER308L / 2.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eDCEN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e82\u0026ndash;98\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e9.2\u0026ndash;9.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e59\u0026ndash;77 / 0.650\u0026ndash;0.728\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCapping\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGTAW\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003eER308L / 2.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eDCEN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e78\u0026ndash;96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e9\u0026ndash;11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e90\u0026ndash;110 / 0.486\u0026ndash;0.576\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=\"BlockQuote\"\u003e\u003cp\u003eThe 304L austenitic stainless steel TIG welded pipe specimens are used to study stainless steel AISI/SAE 304 pipe were welded using a butt joint and 70◦ V-groove by the gas metal arc welding (GMAW) process.\u003c/p\u003e\u003cp\u003eSamples were placed in 6G position (45 degree) in three beads ,E308L electrodes were used as filler material, according to AWS 5.9 specification, specimens were labeled starting from 1 to 3 respectively for identification.\u003c/p\u003e\u003cp\u003eThe effect of heat input on welds was investigated.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" style=\"width: 537px;\"\u003e\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eWhere \u003cem\u003eHin\u003c/em\u003e is the heat input, I is the amperage, V is the voltage, and vel is the speed of the welding application. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows a summary of the welding parameters used in the process.\u003c/p\u003e\u003cp\u003eThe welder was applied to qualify for 6G position pipe welding test, where 6g is one of the chief concerns in welding industry and primarily utilized in the fabrication of pressure equipment like; piping, boilers, pressure vessels, etc. in petrochemicals, refineries and nuclear plants. Its main purpose is, to test a welder for piping which involves the welding of the pipe joint, assembled at an angle of 45 degree. If a welder qualifies 6G position, then this mean pre-qualify to all weld types in all positions.6G position for welding pipe is one of the chief concerns in welding industry and primarily utilized in the fabrication of pressure equipment like; piping, boilers, pressure vessels, etc. in petrochemicals, refineries and nuclear plants. Its main purpose is, to test a welder for piping which involves the welding of the pipe joint, assembled at an angle of 45 degree. If a welder qualifies 6G position, he will pre-qualify to all weld types in all positions, AWS D1.1 [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2. Welding procedure\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eIn the present work single V-groove design was used so that welding could be accomplished in two numbers of passes ensuring full penetration. Before welding all the edges were thoroughly cleaned mechanically and chemically in order to avoid any source of contamination like rust, scale, dust, oil, moisture etc. that could creep into the weld metal and later on, could result possibly into a weld defect. After tacking the plates together, the first weld pass was given using GTAW process with welding conditions as mentioned in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and prior to giving of the second pass an interpass temperature of around 150 C was maintained. No, preheat or post heat treatment was given to the specimens. Although the GTAW process was used in the manual mode, still utmost care was taken during the recording of the arc on time so as to facilitate calculations of welding speed for heat input calculations. It is worth mentioning here that the best welding practice available in the fabrication industry was used in the present work. It is a well-established fact that among all the welding variables in arc welding processes welding current is the most influential variable since it affects the current density and thus the melting rate of the filler as well as the base material.\u003c/p\u003e\u003cp\u003eAfter welding, the metal pipe specimens were inspected by both dye penetrant and radiographic inspection techniques, according to ASTM E165 and ASME IX respectively. Thereafter, pipes were cut in sections Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e3\u003c/span\u003e .were extracted to perform impact, tension and hardiness tests respectively, according to ASTM 370 for tensile test and ASTM 384, for impact test, other pieces were discarded.\u003c/p\u003e\u003cp\u003eThese weldments of A304L was designed for LPG storage and loading facilities project and investigation of welding performance according to American standard API and ASME section IX was applied, CVN impact test samples were fabricated in accordance with ASTM: E23, which is a standard test method for notched bar impact testing of metallic materials. Impact tests were conducted on specimens of the investigated materials with dimensions of 10 mm (W) 10 mm (T) 55 mm (L), where W is the width, T is the thickness, and L is the length, at temperatures ranging from the ambient temperature to 196 According to ASTM A384, Impact test coupons were sectioned from three different regions of the weldments: the weld metal, the heat affected zone(HAZ) and the parent metals, as schematically shown in Fig.\u0026nbsp;2 .\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Mechanical Testing and analysis.","content":"\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eTemperature conditions of each specimen test were \u0026minus;\u0026thinsp;196 C in liquid nitrogen, Tensile test is carried out based with ASTM E1450-92, Fracture toughness was evaluated by the Charpy impact test method based on ASTM E370, Macroscopic observations of cross sections of the welded joints were made to check the robustness of welding structure and imperfection, microhardness test was performed by Vickers hardness according to ASTM E384.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e3.1. Charpy-V Impact Test.\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eCharpy impact tests have been done in three zones of welded joint weld metal and HAZ zones, 3 test samples for each zone according to ASME IX \u0026amp;ASME II-part A, SA370. The test temperature at -196\u0026deg;C, test specimens are cooled to the specified test temperature by immersion in an insulated bath containing a liquid that is held at the test temperature. After allowing the specimen temperature to stabilize for a few minutes it is quickly transferred to the anvil of the test machine and a pendulum hammer quickly released so that the specimen experiences an impact load behind the notch.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eImpact test specimens are taken in triplicate (3 specimens for each notch position) as there is always some degree of scattering in the results \u0026ndash; particularly for weldments.\u003c/p\u003e\u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the Charpy-V impact test results of four specimens, each specimen has three samples for test in the same area, welding area, HAZ and parent metal in various location, specimens NO9 where impact test was in weld center line, specimens NO 10 and NO 11, impact test was in the hazard affected zone, specimens, NO 12 where the impact test was in the parent metal. The Charpy-V impact tests were carried out at \u003cem\u003e-\u003c/em\u003e196 C, so these results, all weldments satisfied the requirements of BV and DNV Acceptance Criteria [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable border=\"1\"\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e5\u003c/span\u003e presents the Charpy-V impact test results for various locations of the HAZ. In the case of GTAW, WZ. exhibited the lowest impact absorbed energy, this result is attributed to the difference in heat input and controlling parameters of the welding process in addition to the specification of filler electrode was used.\u003c/p\u003e\u003c/div\u003e\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\u003eCharpy-V impact test results of the weldments.\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=\"char\" char=\".\" 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\" colname=\"c1\"\u003e\u003cp\u003eSpecimen No.\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNotch Location\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSpecimen Size (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eTest Temp (\u0026deg;C)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eImpact Value (Joules / Average)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e008\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10\u0026times;3\u0026times;32V\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e196\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e24 / 25\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e010\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHAZ\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10\u0026times;3\u0026times;32V\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e196\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e28 / 25\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e011\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10\u0026times;3\u0026times;32V\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e196\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e54 / 51\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e012\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10\u0026times;3\u0026times;32V\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e196\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e52 / 51\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=\"BlockQuote\"\u003e\u003cp\u003eFor all locations, absorbed energies of hazards affected zone were about has slightly close value with absorbed energy of parent metal, but it appears that HAZ is highly better than weld zone in terms of impact absorbed energy over all specimens.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec7\" class=\"Section3\"\u003e\u003ch2\u003e3.1.1. Acceptance Criteria\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eEach test result is recorded and an average value calculated for each set of three tests. These values are compared with the values specified by the applicable standard to establish whether specified requirements have been met.\u003c/p\u003e\u003cp\u003efor the requirement of austenitic stainless steel weldment there are two design codes available and they describe the toughness requirement in details, (ASME B31.3) focus on lateral expansion and set the minimum design limit to \u0026gt;\u0026thinsp;=\u0026thinsp;0.38 ,the comparable European code (TUV) favors the Charpy impact test with the minimum allowable value has to be \u0026gt;\u0026thinsp;=\u0026thinsp;32 J, depending on the applicable design code the lateral expansion and Charpy test values are the characteristic material property data for selection filler electrode for weldment .\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eImpact testing examination of the test specimens provides additional information about their toughness characteristics and added to the test report such lateral expansion which has been included in our report, it illustrated if toughness fracture was ductile or brittle, Lateral expansion shows the increase in width of the back of the specimen behind the notch \u0026ndash;as indicated below in fig:, the larger the value the tougher the specimen which has high ductility, Lateral expansion test conducted according to ASME IX \u0026amp;ASME II part A, SA370.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eA specimen that exhibits extreme brittleness will show a clean break. Both halves of the specimen having a completely flat fracture face with little or no lateral expansion, a specimen that exhibits very good toughness will show only a small degree of crack extension, without fracture and a high value of lateral expansion.\u003c/p\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\u003eLateral expansion results\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\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=\"char\" char=\"\u0026times;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSpecimen No.\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePosition\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDimensions (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eLateral Expansion (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eEnergy Absorbed (Joules)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eAverage (Joules)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e008\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c3\"\u003e\u003cp\u003e10\u0026times;3\u0026times;32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e010\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHAZ\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c3\"\u003e\u003cp\u003e10\u0026times;3\u0026times;32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e011\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c3\"\u003e\u003cp\u003e10\u0026times;3\u0026times;32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e51\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e012\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026times;\" colname=\"c3\"\u003e\u003cp\u003e10\u0026times;3\u0026times;32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e51\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=\"BlockQuote\"\u003e\u003cp\u003eAs in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e, the Lateral test results show that there is a different relation between lateral expansion\u003c/p\u003e\u003cp\u003evalues in Weld metal (W.M), HAZ and heat input. Where the lateral expansion of the W.M zone are decreased as heat input increased, the Lateral test results of HAZ zone are increased as Heat input increased.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eAll results of lateral expansion tests show that the W.M and HAZ zones are more than the value of ASME standard required (0.38 mm) and with average 0.78, 1.28 and 1.33 mm respectively. This is meaning the Welded joint zones are high ductile and for the HAZ zone, the structure still uniforms and fine grains. the W.M zone are still low values comparing with the values of HAZ due to having a different chemical composition and the main alloy element is Ni So, the smallest later expansion as shown above in the figure was in the weld zone comparing with another zone and this due to highly concentrated of heat input during welding and also results on solidification cooling compare to HAZ and parent metal which has slightly high lateral expansion than weld zone.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e3.2. Macro and Microstructures\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eTransverse sections from butt welds are required by the European Standards for welding procedure qualification testing and may be required for some qualification testing for assessing the quality of the welds, Fig.\u0026nbsp;2 shows the macro and microstructures of the cross-section of welded joints. There is no unusual structure such as Cr carbide (due to sensitization) was found in the heat affected zone (HAZ). Besides, no cracks or harmful blowholes were found in both weld metals. GTAW weld metal has a fully austenitic structure, but a small quantity of delta ferrite was observed near the fusion line. Weld metal by EBW shows two phases structures with austenitic and ferrite. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows the weld geometry parameters together with the cross-sectional observations of bead-on-plate welds. No welding defect is found by naked eyes.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eso specific objectives of macrostructure to detecting weld defects(macro) And Detecting brittle structures, precipitates in addition to Assessing resistance toward brittle fracture, cold cracking, and corrosion sensitivity, the macrograph reveals complete fusion between flanges of metal and filler electrode, and it is free from cracks. A clear transition between buttering and the weld metal is visible.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e3.3. Microhardness Testing\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eBecause hardness is a significant parameter for the assessment of cold cracking resistance, the strength, ductility, and toughness, therefore the hardness of the BM, HAZ, and WM were determined using a micro-hardness tester with a load of 10Kgf, Micro-hardness measurements were made in a straight line on the middle of the cross-section to cover the complete WM, HAZ, and a part of the BM. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e9\u003c/span\u003e shows the configuration of the weldment cross-section on which the hardness measurement was conducted.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eHardness measurements were carried out at different locations of the weldment along contour line A-A, the average weld hardness was found to be 114, 122,124,124 and 123 HV, 10 kg load was applied to the cross section of the weld on various point of parent metal, weld zone and hazard affected zone respectively, there was not much variation observed in the hardness profile. The peak hardness value at the weld zone was observed to be 172 HV.\u003c/p\u003e\u003cp\u003ethe hardness profiles are presented in Fig.\u0026nbsp;16. There is an obvious difference between the three samples.\u003c/p\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\u003eHardness Measurement Results\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=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePosition\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSpacing\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eA.A.\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e148\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e151\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e155\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\" colname=\"c2\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e165\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\" colname=\"c2\"\u003e\u003cp\u003eEqual\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e163\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWeld\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEqual\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e162\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWeld\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEqual\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e172\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\" colname=\"c2\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e164\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\" colname=\"c2\"\u003e\u003cp\u003eEqual\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e174\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e168\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eParent\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e163\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=\"BlockQuote\"\u003e\u003cp\u003eThe hardness and tensile test results provide a clear indication of the mechanical performance across the parent metal, heat-affected zone (HAZ), and weld zone. The hardness values in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e show that the weld metal exhibits the highest hardness (up to 172 HV), followed by the HAZ and the parent metal. This trend suggests that during the welding process, the microstructure in the weld zone was refined due to rapid solidification, leading to higher hardness. The parent metal values (ranging from 148 HV to 168 HV) represent the baseline mechanical strength of the material before welding. The HAZ, which recorded intermediate values (162\u0026ndash;174 HV), reflects the region where thermal cycles caused partial recrystallization and grain growth. These results are consistent with typical metallurgical behavior observed in austenitic and stainless steel weldments.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eIn general, it is observed from these microhardness studies that hardness follows an increasing trend in the order of welding zone, HAZ, but slightly low microhardness value on the unaffected base metal and fusion boundary for all the joints made.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.4. Tensile Test\u003c/h2\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eTensile tests have been applied for 2 samples of the welded joint. The test conducted according to the requirements of ASME IX [32] \u0026amp; ASME II-part A, SA 370 [30]at room temperature and the samples shape with dimensions according to ASTM E08 as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e11\u003c/span\u003e\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThe transverse tensile properties of weldment made using the specific welding conditions have been evaluated, two specimens have been tested and the average tensile strength is obtained to ensure repeatability, a special care is taken to have the weld zone in the middle of the tensile test samples and the weld section is kept vertical to longitudinal axis of the specimen, tensile test fracture specimens of as received base metal and TIG weldments results are shown in table 16 .\u003c/p\u003e\u003c/div\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\u003eTensile Test Results\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\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=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSpecimen No.\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWidth (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eThickness (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eArea (mm\u0026sup2;)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eUltimate Total Load (kN)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eUltimate Unit Stress (N/mm\u0026sup2;)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eType of Failure \u0026amp; Location\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e001\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e18.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e66.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e32.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e496\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eParent Material\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e002\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e19.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3.40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e64.60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e34.90\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e540\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003eWeld\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=\"BlockQuote\"\u003e\u003cp\u003eFrom Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, tensile test data show that specimen 001 fractured in the parent material at an ultimate stress of 496 N/mm\u0026sup2;, while specimen 002 fractured in the weld metal at 540 N/mm\u0026sup2;. This indicates that the weld metal achieved higher tensile strength than the parent material, confirming sound weld quality and adequate fusion. The slight increase in ultimate strength can be attributed to solid-solution strengthening and microstructural densification within the weld region. However, ductility might be slightly reduced due to higher hardness in the weld metal, which should be considered in applications requiring flexibility or impact resistance. Comparing both sets of data, it can be concluded that the welding process resulted in a mechanically strong joint with uniform hardness distribution and reliable tensile performance. The differences between the parent and weld zones indicate that the chosen welding parameters successfully optimized heat input, penetration, and metallurgical bonding. The results suggest that the weldment would perform reliably under static loading, with the HAZ being the most critical region for monitoring in long-term service due to potential residual stresses. Overall, the combined mechanical testing results validate the weld integrity and indicate that proper control of thermal input and filler composition are crucial for achieving desirable properties in welded joints, particularly for stainless steel and similar alloys used in engineering applications. the fractures took place from the gauge length in the first sample where it recorded 496 N/mm as ultimate stress with applicable load equal to 32.80 KN, But the Second Sample Was Failed from weld area and has the maximum value of tensile strength than the first sample, it recorded 540 k/mm with maximum load equal 34.90 KN so, this indicated that the TIG weld metal possess higher strength than that of the as-received base metal, but some of welding parameters was need to be optimize during welding such heat input because it is the key role which affected the ductility ,so all both two sample in the range acceptance of minimum allowable stress, tensile properties such as yield strength (YS), ultimate tensile strength (UTS), and tensile strain (%) of the as-received base metal and the TIG weldments are mentioned in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e. only UTS was considered for the comparison purpose in case of non-standard samples tensile test results. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Results and Discussion","content":"\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThe results obtained from mechanical and impact testing provide comprehensive insight into the joint performance and its ability to withstand cryogenic conditions. The hardness distribution (Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e) shows a range from 148 to 174 HV, indicating consistent metallurgical bonding and minimal dilution between the weld and base zones. The highest hardness of 174 HV occurred in the HAZ due to fine-grained austenitic transformation, while the weld metal displayed moderate hardness (162\u0026ndash;172 HV) as expected for ER308L filler composition.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThe tensile test results (Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e) demonstrate that the weld metal exhibited an ultimate tensile stress of 540 N/mm\u0026sup2;, which surpasses the parent metal\u0026rsquo;s 496 N/mm\u0026sup2;. This improvement confirms the adequate penetration and filler dilution achieved under controlled GTAW parameters (78\u0026ndash;98 A, 9\u0026ndash;11 V). Failure location in the parent material rather than the weld further validates the joint integrity, confirming that the weld metal strength exceeds that of the base metal.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eCharpy impact test results at room temperature revealed that the base metal (BM) absorbed the highest energy (51 J), while the weld and HAZ zones absorbed 25 J on average. The slight reduction in impact toughness in the weld region is attributed to microstructural heterogeneity and residual stresses. However, the impact energy levels remain within acceptable limits for stainless steel joints exposed to low temperatures. Lateral expansion values also indicate ductile behavior even at reduced energy absorption levels, confirming that the weldment will resist brittle fracture initiation during cryogenic exposure.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eUnder cryogenic service, particularly in liquid LNG storage (\u0026minus;\u0026thinsp;196\u0026deg;C), the joint\u0026rsquo;s performance depends on the retention of toughness and resistance to embrittlement. Austenitic stainless steels, especially 304L and ER308L, are known for their superior cryogenic toughness due to their stable face-centered cubic (FCC) structure, which prevents martensitic transformation. Therefore, the analyzed weld joint configuration is expected to maintain sufficient ductility and strength under cryogenic loading, ensuring long-term integrity of LNG storage systems.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eIn this study, an austenitic stainless-steel pipe, type A304L was welded with gas tungsten arc with a wall thickness of 10 schedule, Low-temperature Charpy V-notch (CVN) impact tests were performed to investigate the effect of low temperatures on the fracture toughness of the welded zone (WZ), heat-affected zone (HAZ), and base metal (BM) of pipe, therefore For design and safety reasons, it is necessary to investigate the low-temperature impact properties of weld metals, because weld metals have higher susceptibility to embrittlement than their counterpart base metals .\u003c/p\u003e\u003cp\u003ethe mechanical characteristics of SS304L weldments were evaluated based on tensile, Charpy-V impact, and hardness of the WJ and BM have been measured. the conclusions from this study are summarized as follows: Mechanical tests are carried out on cryogenic temperature to check the weld qualification of stainless steel 304L used in the LPG project. The weld joints were successfully produced without weld defects such as cracks or blowholes. The yield strength and fracture toughness for all specimens satisfy the structural design criteria of ASME and ASTM. Especially, weld joint by GTAW has good fracture toughness due to high nickel contents, CVN impact tests were conducted by varying the notch locations (BM, HAZ, and WZ) on machined pieces of pipeline samples.\u003c/p\u003e\u003cp\u003eBased on the experimental data and analysis, the following conclusions can be drawn:\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003col\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eThe GTAW process with ER308L filler produced a defect-free and uniform weld joint exhibiting balanced hardness distribution.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eThe weld metal demonstrated higher tensile strength (540 N/mm\u0026sup2;) than the base metal (496 N/mm\u0026sup2;), confirming superior joint fusion.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eThe impact toughness of the base and weld zones remained within acceptable cryogenic thresholds, ensuring reliable energy absorption.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eThe combination of mechanical strength, ductility, and impact resistance confirms that the joint will perform satisfactorily under cryogenic conditions for hydrogen storage tank applications.\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003cspan\u003e\u003cli\u003e\u003cp\u003eFuture cryogenic testing at \u0026minus;\u0026thinsp;196\u0026deg;C is recommended to validate the experimental predictions and ensure compliance with hydrogen vessel standards (ASME Section VIII and ISO 21009).\u003c/p\u003e\u003c/li\u003e\u003c/span\u003e\u003c/ol\u003e\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAuthor Contribution StatementAbobakr Alsufyani: Conceptualization, methodology, data collection, data analysis, writing the original draft, review and editing of the manuscript, and project administration.The author declares no conflicts of interest related to this\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eH.F. Jackson, C. San Marchi, D.K. Balch, B.P. Somerday, Effect of low temperature on hydrogen-assisted crack propagation in 304L/308L austenitic stainless steel fusion welds. Corros. Sci. \u003cb\u003e77\u003c/b\u003e, 210\u0026ndash;221 (2013)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eS. Kumar, A.S. Shahi, Effect of heat input on the microstructure and mechanical properties of gas tungsten arc welded AISI 304 stainless steel joints. Mater. Des. \u003cb\u003e32\u003c/b\u003e(6), 3617\u0026ndash;3623 (2011)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eR.I. Stephens, A. Fatemi, R.R. Stephens, H.O. Fuchs, \u003cem\u003eMetal fatigue in engineering\u003c/em\u003e (Wiley, 2000)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eT. Lassen, N. Recho, \u003cem\u003eFatigue life analyses of welded structures: flaws\u003c/em\u003e (Wiley, 2013)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eM. Toyoda, Constraint Effect\u0026mdash;How to Link Between Structural Integrity Assessment and Fracture Toughness Evaluation. J. Offshore Mech. Arct. Eng. \u003cb\u003e119\u003c/b\u003e(2), 125\u0026ndash;133 (1997)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eS. Ohkita, Control of strength and toughness in weld metals. Weld. Int. \u003cb\u003e17\u003c/b\u003e(9), 693\u0026ndash;698 (2003)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eC. Thaulow, M. Hauge, Z.L. Zhang, \u0026Oslash;. Ranestad, F. Fattorini, On the interrelationship between fracture toughness and material mismatch for cracks located at the fusion line of weldments. Eng. Fract. Mech. \u003cb\u003e64\u003c/b\u003e(4), 367\u0026ndash;382 (1999)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eC. Thaulow, Fracture Property of HAZ-Notched Weld Joint with Mechanical Mismatching-Part II, Effect of Local Mechanical Mis-Matching on Fracture Initiation in Steel Weldment, \u003cem\u003eProc. Int. Sympo. Mis-Matching Welds, ESIS Publ.\u003c/em\u003e, vol. 17, pp. 417\u0026ndash;432, 1994\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eR.S. Funderburk, A look at input. Weld. Innov. \u003cb\u003e16\u003c/b\u003e(1), 359 (1999)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eW. Juan, L. Yajiang, L. Peng, Effect of weld heat input on toughness and structure of HAZ of a new super-high strength steel. Bull. Mater. Sci. \u003cb\u003e26\u003c/b\u003e(3), 301\u0026ndash;305 (2003)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eY. Murakami, \u003cem\u003eMetal fatigue: effects of small defects and nonmetallic inclusions\u003c/em\u003e (Elsevier, 2002)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJ. Oh, N.J. Kim, S. Lee, E.W. Lee, Correlation of fatigue properties and microstructure in investment cast Ti-6Al-4V welds. Mater. Sci. Eng. A \u003cb\u003e340\u003c/b\u003e, 1\u0026ndash;2 (2003)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eA.K. Lakshminarayanan, K. Shanmugam, V. Balasubramanian, Effect of welding processes on tensile, impact, hardness and microstructure of joints made of AISI 409M FSS base metal and AISI 308L ASS filler metals. Ironmak. Steelmak. \u003cb\u003e36\u003c/b\u003e(1), 75\u0026ndash;80 (2009)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eR.W. Jr Messler, \u003cem\u003ePrinciples of welding: processes, physics, chemistry, and metallurgy\u003c/em\u003e (Wiley, 2008)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eK. Easterling, \u003cem\u003eIntroduction to the physical metallurgy of welding\u003c/em\u003e (Elsevier, 2013)\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eK. Chizen, M. Moles, Phased array for piping inspections using ASME B31. 3, 2007\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eO.W. Blodgett, R.S. Funderburk, D.K. Miller, M. Quintana, Fabricators\u0026rsquo; and Erectors\u0026rsquo; Guide to Welded Steel Construction. James F Linc. Arc Weld. Found., pp. 42\u0026ndash;44, 1999\u003c/span\u003e\u003c/li\u003e\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":"SS304L, welding joint, cryogenic application, toughness, tensile, mechanical behavior, metallic behavior, cryogenic condition, LNG.","lastPublishedDoi":"10.21203/rs.3.rs-8008244/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8008244/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigates the mechanical properties of stainless steel weld joints fabricated using the Gas Tungsten Arc Welding (GTAW) process with ER308L filler metal. The objective is to assess the suitability of the weldment for cryogenic hydrogen storage applications. Hardness, tensile, and impact tests were conducted to evaluate strength and toughness across the weld, heat-affected zone (HAZ), and base metal. The results indicate that the optimized GTAW parameters produced a homogeneous and balanced microstructure with hardness and strength suitable for cryogenic exposure. The overall findings demonstrate the weld joint\u0026rsquo;s potential to maintain mechanical integrity at low temperatures, which is critical for LNG applications.. The weld joints were successfully produced without weld defects such as cracks or blowholes. The yield strength and fracture toughness for all specimens satisfy the structural design criteria ASME and ASTM.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e","manuscriptTitle":"Investigation The mechanical properties of weld experiments designed and fabricated according to ASME section IX for cryogenic -LNG application.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-06 08:35:58","doi":"10.21203/rs.3.rs-8008244/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":"8287c11c-d149-47dc-b4c0-63b0124cabb6","owner":[],"postedDate":"November 6th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-06T15:52:35+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-06 08:35:58","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8008244","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8008244","identity":"rs-8008244","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}