Mechanical and electrochemical analysis of AA5083-AA7075 dissimilar alloy joints fabricated by friction stir welding

Mechanical and electrochemical analysis of AA5083-AA7075 dissimilar alloy joints fabricated by friction stir welding | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Mechanical and electrochemical analysis of AA5083-AA7075 dissimilar alloy joints fabricated by friction stir welding Meghavath Mothilal, Atul Kumar, Mahesh VP, Sandeep Rathee This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6718161/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 aims to enhance high strength (AA7075), high-corrosion resistant (AA5083) dissimilar joints of Aluminum (Al) alloys employing friction stir welding (FSW) technique for marine applications. The dissimilar weld of Al alloys was fabricated with standardized FSW process parameters (i.e., 1100 rpm of tool rotational speed, 2° tilt angle, and 50 mm/min of welding speed). Detailed analysis of weld characteristics, mechanical properties, and corrosion behaviour are carried out to establish the effectiveness of the FSW technique for dissimilar welding. The hardness profiles across the weld regions revealed a notable increase in hardness within the stir zone when compared to the base metals, which is attributed to the fine-grained microstructure produced during the FSW process. The optimized FSW joint's ultimate tensile strength (UTS) is 80% of the AA7075 base metal, indicating good joint efficiency. Microstructural analysis through optical microscopy and SEM provides insights into the grain structure and phase distribution within the weld zone. The stirred zone exhibits a refined equiaxed grain structure due to the effect of dynamic recrystallization during FSW. Corrosion behavior was assessed using Tafel plots and Electrochemical impedance spectroscopy (EIS). The Tafel plots illustrated that the welded joint exhibited a corrosion potential and current density comparable to that of the base metals, suggesting that the FSW process did not lower the corrosion resistance of the materials. EIS results provided further evidence of the weld's stability in corrosive environments, with impedance spectra indicating better corrosion resistance. Corrosion resistance scanning electron microscopy friction stir welding microstructure microhardness Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 1. Introduction Al alloys are generally utilized in an engineering field, mainly in the marine-related applications, owing to their superior strength and corrosion resistance [ 1 ]. Nonetheless, amalgamating these alloys with dissimilar characteristics, such as the high-strength 7xxx series and the corrosion-resistant 5xxx series, creates challenges for shipbuilding applications. Traditional fusion welding methods, such as gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW), frequently encounter efficiency issues due to the creation of brittle intermetallic compounds (IMCs) and porosity [ 2 , 3 ]. FSW has been implemented to mitigate obstacles since it efficiently resolves issues like solidification cracking and porosity [ 4 , 5 ]. The Welding Institute (TWI) pioneered the development of FSW in the 1990s. FSW provides a unique approach for joining materials without the need to melt them [ 6 ]. It employs a rotating H13 tool to produce heat via friction between the workpiece, resulting in the plastic mixing of the materials at the weld joint [ 7 , 8 ]. This process arises at temperatures under the melting points of the workpieces, hence mitigating the emergence of undesirable phases and defects usually linked to traditional welding techniques [ 9 ]. FSW has shown effectiveness in joining various aluminum alloys, resulting in enhanced mechanical properties and more excellent corrosion resistance compared to traditional welding methods [ 10 , 11 ]. FSW leads to the creation of multiple zones: the heat-affected zone (HAZ), the thermomechanically affected zone (TMAZ), and the nugget zone (NZ). NZ is where the actual weld joint is created through plastic deformation and recrystallization[ 12 ]. Adjacent to NZ, TMAZ is present under the shoulder of the tool and undergoes plastic flow, while recrystallization does not occur [ 13 ]. Besides the TMAZ on the base material (BM) side, the HAZ experiences metallurgical changes due to the thermal gradient from the welding process [ 14 , 15 ]. The varying microstructure of the zones results in different due to various electrochemical, mechanical, and physical factors. Microstructure of the FSWed joint is influenced by several process parameters, which are rotational speed (R), welding speed (W), axial force (AF), tilt angle (T), the dwell phase (the period during the rotating tool remains idle after plunging), and tool design (TD) [ 16 – 18 ]. The study examined how the parameters and tool pin/probe profiles on the mechanical and microstructural properties of AA2219 Al alloys across the plate thickness. The study evaluated how varying FSW weld process parameters affected underwater welding, showing that a higher cooling rate improved the properties of the FSW joint. Additionally, another investigation indicated that the heat input during the welding process had a more significant effect on the residual stress and mechanical properties of a specific FSW weld joint than the deformation caused by the tool [ 19 , 20 ]. Variations in microstructural and mechanical characteristics were observed in dissimilar FSW (DFSW) weld joints of Al alloys because of different welding process conditions or parameters. Furthermore, the study revealed that the R-to-W ratio significantly influenced tensile and fatigue properties in the FSW of AA2198 Al-Li alloy [ 21 ]. The gel visualization methodology was used to examine how various FSW parameters affect the extent of the corrosion on the AA2024 plate [ 22 ]. It was found that the R (rpm) had a significant impact on the corrosion susceptibility. Analyzing corrosion resistance at different areas within the NZ and throughout the thickness of the plate revealed that corrosion resistance has been decreased as the R (rpm) and W (mm/min) increased [ 23 , 24 ]. The optimal combinations of R and W were identified to achieve the best corrosion performance for plate AA5052 in the FSW joint [ 25 ]. Additionally, Finer grain structures were observed as the W increases, which enhanced corrosion resistance by establishing a protective coating within the FSW joint of AA6061 [ 26 ]. The corrosion resistance of DFSW weld joints was assessed under several welding parameters; it is shown that the joints with lower heat input demonstrated the best corrosion resistance [ 27 ]. This research highlights the complex interplay between FSW parameters, microstructural changes, and the corrosion susceptibility of AA7075 [ 28 ]. It specifically notes the negative influence of precipitation distribution and the size of the grain boundaries (GBs) on corrosion resistance. However, the use of secondary heating emerges as a promising technique to minimize corrosion tendencies in AA7075 welds by improving microstructural changes and modifying precipitation distribution [ 29 , 30 ]. Further research is needed to comprehend the metallurgical, materials properties and the corrosion resistance of FSWed joints. Presently, there is limited literature available in the field of corrosion, metallurgical and mechanical behavior of DFSW joints of AA5083-AA7075 Al alloys. Therefore, it is essential to examine the comprehensive study to ensure the reliability and corrosion resistance of the DFSW weld joint. This research seeks to assess how the FSWed zones influence the mechanical, metallurgical, and electrochemical behaviour of the joint through tensile testing, Vickers microhardness, macro and microstructure analysis, scanning electron microscopy (SEM), EIS, and Tafel testing. 2. Materials and methodology As received, base materials of AA7075 (B7) and AA5083 (B5) (Bharat Aerospace Metals Mumbai, India) were utilized for the FSW butt joint. They were prepared using a wire-cut electrical discharge machine (EDM) with Length x width x thickness = 110 x 7 x 5 mm. The composition (wt.%) of AA7075 includes 5.29% Zn, 1.71% Cu, 2.46% Mg, 2.21% Cr, 0.06% Mn, 0.23% Fe, 0.20% Si, 0.03% Ti, and the remainder is aluminum. In contrast, AA5083's composition consists of 0.25% Zn, 0.10% Cu, 4.50% Mg, 0.15% Cr, 0.40% Si, 0.50% Mn, 0.02% Ti, 0.40% Fe, and the remainder is aluminum [ 31 ]. Optical microscopy is used to analyze the microstructural characteristics of these base metals, as illustrated in Fig. 1. Contamination (dirt) on the surface of the plates was removed with the help of ethanol before starting the joining of the workpieces, and then the plates were clamped tightly on the fixture. These two Al-alloy plates (AA7075 and AA5083) were joined using an FSW machine with a non-consumable rotating cylindrical tapered threaded H13 steel tool, and the dimensions are represented in Fig. 2. The AA7075 was situated on the advancing side (AS), whereas the AA5083 was set on the retreating side (RS), as illustrated in Fig. 3. All the experiments were conducted at an optimized FSW process parameter of tool R 1100 rpm, T 2˚, and W 50 mm/min. The transverse joints were maintained at a right angle to the rolling direction of the BM. The micro and macrostructural specimens were cut into 10 mm x 10 mm to analyze. The specimen was polished with emery sheets of 220 to 2000 grit size. Then, cloth polishing was done with alumina to get a mirror-like surface for the analysis of macrostructure, microstructure, and corrosion. The specimen is etched with Keller's reagent (composition) for 30 seconds to reveal the grain boundaries (GBs). Optical microscopy (Make: Olympus, Model: Olympus BX61) was utilized for the microstructural analysis. The SEM (Model - Carl Zeiss, Make - Evo 18 Research). The microhardness test was carried out by utilizing Vicker’s microhardness tester (Model: MMT X7B Make: Matsuzawa Co. Ltd.) on the traverse-section of dissimilar joined sample, as specified by ASTM E-384. The tensile samples were taken from the base plates and welded plates following the guidelines of ASTM E-8. The tensile testing was performed by a 100kN capacity UTM (Model: 8801, Make: Instron) to determine the UTS of the weld joint. The corrosion behavior of B7 and B5, as well as the weld zone (WZ), was assessed using potentiodynamic polarization (PP) and EIS tests. Samples were polished to a mirror finish prior to testing to ensure surface quality. A 3.5% sodium chloride solution at room temperature was used for the corrosion tests. A standard 3-electrode setup was used, with a sample as the working electrode, a saturated calomel electrode as the reference, and platinum wire serving as the counter electrode. The PP test was conducted within the potential range − 1.5 V to + 1.5 V relative to the open-circuit voltage (OCV) at a scan rate of 1 mV/s. An open circuit delay (OCD) time of 1800 seconds was applied prior to the measurements. EIS was conducted over a 10 kHz to 0.01 Hz frequency range at the OCV with an AC amplitude of 10 millivolts (mV). Potentiodynamic polarization (Make: Ivium Potentiostat, Model: Vertex One) was used for the electrochemical studies, and the data was analyzed using the corresponding software. 3. Results and discussion 3.1. Macrostructure The weld joint was created using the optimized process parameter and was examined using a stereo-zoom microscope to assess the development of specific zones within the weld. As represented in Fig. 4 , the macrostructure reveals a clean weld interface free of cracks and defects, highlighting the effectiveness of the optimized FSW parameters in achieving sound joint quality. While material deformation is evident on the advancing and retreating sides of the weld due to the heat generated by a rotating tool, the macrostructure exhibits variations across the weld region [ 32 ]. FSWed joints typically exhibit distinct zones, each characterized by unique microstructural features. When considering the DFSW joint, the stirred zone appears wider at the upper section due to the influence of the rotating shoulder. In contrast, the TMAZ, characterized by partially deformed and elongated grains, is also more pronounced on the top side. This heterogeneity in grain structure across the WZ significantly influences the mechanical integrity and corrosion performance of the joint [ 23 ]. 3.2. Microstructure The metallographic samples (cross-section area in the traverse direction) were analyzed to study the microstructure of the optimized DFSW weld joint. Figure 5 shows different microstructures in the weld zones, such as HAZ, TMAZ, and the NZ. Delicate equiaxed grain structures are shown to develop within the NZ. This development occurs due to the dynamic recrystallization induced by thermal and mechanical conditions during the FSW process [ 33 ]. The material in that area experienced significant plastic deformation, producing refined smaller grains caused by the mechanical stirring effect of the rotating probe [ 34 , 35 ]. Figure 5 illustrates the NZ on both sides of plate RS and plate AS. The grains adjacent to these boundaries appear elongated, while finer grains are located within the NZ. The fine-grained structure in the NZ enhances its strength, as demonstrated by the hardness measurements presented in the microhardness section [ 36 ]. Welding joints of various materials pose challenges due to their differing mechanical characteristics like, tensile, hardness, and metallurgical properties, such as microstructure and macrostructure [ 37 , 38 ]. Both AA5083 and AA7075 show significant differences in grain deformation because of their distinct material properties. The TMAZ of plate RS exhibits the development of reveals the presence of smaller grains of irregular shape, as illustrated in Fig. 5 (b). In contrast, the TMAZ of AS (Fig. 5(a)) displays a banded grain structure at the NZ, causing the BM (Fig. 1(a)) to deform toward the NZ. As a result, grain deformation occurs in workpieces. The HAZ of AS exhibits enlarged grains due to the thermal influence from the NZ and the TMAZ of the same material. Furthermore, the AS of the weld experiences greater deformation and produces increased heat while stirring action in comparison to the RS of the weld. The HAZ of RS reveals a larger grain size than the BM (Fig. 1(b)) of the same, which primarily accounts for the weakened hardness and increased risk of failure relative to the NZ [ 39 ]. 3.3. Microhardness: A microhardness test was done along their cross-section of dissimilar (AA5083 and AA7075) aluminum alloy samples using a 100-gf load applied for 15 seconds and measured at every 0.75 mm interval, in line with ASTM E-384. The findings in Fig. 6 illustrate a distinct "W" shaped profile (bar chart), characteristic of FSW weld joints, and signaling microstructural variations across different zones. The highest microhardness value (189 HV) was recorded in the NZ, attributed to the refined grain structure formed through dynamic recrystallization during the friction stir welding process. Hardness consistently decreased from BM (B5-125 HV and B7-197 HV) to HAZ and increased from the HAZ to the NZ on both the AA5083 and AA7075 sides, indicating a finer grain size nearer to the weld centerline. This grain refinement process is driven by the intense thermo-mechanical conditions experienced by the material during the butt joint process. Notably, the HAZ of AA5083 exhibited lower hardness relative to other zones/regions, except for the BM of AA5083. This occurrence may be because of the presence of larger grains in this area, possibly caused by factors such as higher heat input or variations in material characteristics. The presence of these larger grains can act as potential sites for the initiation and propagation of fractures, which could compromise the mechanical integrity of the welded joint. This finding is supported by tensile test results, demonstrating the reduced strength of the HAZ (AA5083 (RS)). The effect of the FSW process on the microstructure evolution and mechanical response of the material is highlighted by the contrast in hardness between the NZ and the BM. The localized heat produced and distortion during the butt weld results in grain refinement and altered precipitation behavior, ultimately impacting the hardness and overall mechanical performance of the dissimilar butt weld [ 40 ]. 3.4. Tensile testing The tensile tests were conducted on the DFSW Al-alloys weld joints (AA7075-AA5083) using optimized FSW parameters: an R of 1100 rpm, a W of 50 mm/min, and a T of 2˚. Tensile samples were prepared following the standardized dimensions specified in ASTM E-8, as illustrated in Fig. 7. The fractures observed at a 45˚ to the loading direction predominantly occurred in the HAZ of AA5083 on the RS, indicating that this region is the weakest point in the weld. The improved tensile strength in the process, as mentioned above parameters, was confirmed and supported by the microhardness test. Consequently, the B7 strength is higher than that of the FSWed fractured specimen in the HAZ (RS), as shown in the stress vs. strain plot in Fig. 7. Table 1 illustrates the results obtained from the optimized and BMs tensile testing procedure. Table 1 Tensile strength comparison of base alloys with the welded sample Material UTS (MPa) AA7075 Base alloy (B7) 517 AA5083 Base alloy (B5) 284 AA7075-AA5083 Welded sample (WZ) at 1100 rpm (R), 50 mm/min (W), and 2˚ tilt angle (T) 417 3.5. Corrosion analysis of base materials and welded sample The corrosion behavior of B7 and B5, along with the WZ joint, was studied using PP Tafel curves and EIS tests. Each sample's corrosion potential (E corr ) was measured to evaluate its corrosion resistance. The BMs exhibited distinct corrosion behavior, with AA5083 showing better resistance due to the refined grains and the elimination of Al 3 Mg 2 precipitates during FSW processing. Conversely, AA7075, enriched with Mg, Fe, and Si phases, demonstrated increased susceptibility to corrosion due to localized galvanic reactions initiated at Fe-enriched regions, as observed in Fig. 8. The E corr difference is 200 mV between the BM, which highlights the potential for galvanic corrosion when dissimilar joints are formed [ 41 ]. Figure 8 shows the PP test outcomes, which are summarized in Table 2 . This table includes values for corrosion potential and Tafel slopes. The corrosion potential values are close to the open circuit potential (OCP) results presented in Fig. 8. Among the 3 locations, the corrosion current density for B7 is greater than that of the other two locations. The FSWed area displays a corrosion current density comparable to that of B5, which aligns with the fact that the FSW zone consists of material from B5, as illustrated in Fig. 4 . Table 2 Data obtained through analysis of the PP curves are presented in Fig. 8. Work materials Ecorr (mV vs. SCE) i corr (mA/cm 2 ) B5 − 480 1.376 WZ − 730 5.322 B7 − 680 8.549 B5 has better corrosion resistance, as its corrosion current density value is lower compared to B7 and WZ. A higher corrosion current density value corresponds to lower corrosion resistance, and a higher corrosion potential value signifies better corrosion resistance [ 42 , 43 ]. As per Table 2 , B5 has superior potential and lower current density values of corrosion, making it the best material among the three under discussion. BMs' and DFSW's joint corrosion behavior was extensively analyzed using EIS and PP tests. EIS tests using Nyquist and Bode plots revealed the distinct corrosion characteristics for the BM and the FSW joint, enabling the evaluation of their electrochemical stability in a corrosive environment [ 44 ]. In Fig. 9 , the Nyquist plots for B5, B7, and WZ samples exhibited the same shapes but were different in the magnitude of impedance, with larger semicircle diameters showing higher resistance. Lower corrosion resistance was observed in the FSW joint relative to the BMs; this is because of the galvanic coupling of dissimilar weld zones. However, sample B5 demonstrated better corrosion resistance than the tested samples of WZ and B7, as confirmed by both the PP and EIS results. These findings emphasize the impact of material composition, microstructural changes, and precipitation behavior on the corrosion performance of the FSW weld joints. The EIS data for the B7 and B5 exhibited significant differences in the impedance profiles, reflecting their different corrosion behavior. In Fig. 9 , the Nyquist plots for both materials displayed semicircles of various diameters, with B5 showing a larger semicircle than B7. This difference shows that the higher corrosion resistance in B5[ 17 ]. The enhanced performance of B5 is attributed to the dissolution of Al 3 Mg 2 precipitates at higher temperatures, leading to a more refined grain structure and reduced susceptibility to localized corrosion. In contrast, the B7 alloy, enriched with Mg, Si, and Fe phases, exhibited lower impedance values. These phases act as active sites for corrosion, initiating galvanic cells within the aluminum matrix and accelerating the corrosion process [ 45 ]. In Fig. 10 , the Bode plots further validated these observations, showing a higher modulus of impedance and phase angle for B5 across a wide frequency range. These parameters suggest a more stable passive film and greater resistance to charge transfer, contributing to B5's superior corrosion resistance. On the other hand, B7 displayed a lower impedance magnitude, indicating a less protective oxide layer and higher susceptibility to localized attack [ 46 ]. The DFSW joint of AA7075 and AA5083 exhibited a complex impedance response due to the heterogeneity of the WZ. The Nyquist plots displayed a combination of semicircles that corresponded to the mixed regions of these two alloys. Notably, there was a reduction in the diameter of the semicircles compared to the BMs. This finding highlights the lower corrosion resistance of the friction stir welded joint, primarily due to the galvanic coupling between the regions enriched with AA7075 and those enriched with AA5083 within the WZ. The areas rich in AA7075 acted as cathodes, while those rich in AA5083 functioned as anodes, which facilitated the initiation of galvanic corrosion at the boundaries and its subsequent propagation into the AA5083-rich areas. 3.6. SEM Analysis The results of the SEM examination indicate notable differences in the microstructural features and intermetallic compounds present in the BMs and WZ of Al alloy samples that are either affected by corrosion or not. Samples B5 and B7 showed a consistent microstructure with few intermetallic precipitates in the base material regions. In contrast, the WZ samples exhibited a more varied microstructure, marked by a finer grain structure in the nugget area and partially deformed grains in the thermomechanically affected zone (TMAZ) [ 47 ] as shown in Fig. 5. Electrochemical corrosion tests showed that the samples containing corrosion base materials (CB5 and CB7) had lower corrosion resistance compared to the samples without corrosion (B5 and B7). This reduction in resistance is attributed to a higher presence of intermetallic compounds and second-phase precipitates, which provide favorable sites for the initiation of corrosion. The corroded weld zone (CWZ) specimen displayed the lowest corrosion resistance when compared to the non-corroded samples. This can be associated with the complex and heterogeneous microstructural weld region, which consists of various microstructural features. These include the fine-grained nugget, partially deformed grains in the TMAZ, and the coarse-grained HAZ [ 48 ]. The differences in microstructure create microgalvanic cells, which accelerate the corrosion process. In the dissimilar AA7075-AA5083 joint, the presence of blended regions resulted in distinct corrosion characteristics. The areas rich in AA7075 acted as cathodes in relation to AA5083, leading to the initiation of galvanic corrosion along the boundaries of AA7075 before spreading into the AA5083-enriched regions. This behavior is particularly evident in sample B7, which exhibited more pronounced corrosion damage compared to sample B5, which had fewer surface pits (see Fig. 11). The corrosion process eventually transitioned to a more uniform attack along the as-welded surface (Fig. 11), while widespread corrosion was observed throughout the weld zone (WZ) of the joint. Additionally, the iron-enriched regions within the Al matrix further aggravated the corrosion in these joints. EIS and PP tests provided consistent insights into the corrosion resistance of the materials [ 49 ]. 4. Conclusion A comprehensive investigation of the electrochemical characteristics of the friction stir welded joint between AA7075 and AA5083 and the base metals has been conducted. The principal outcomes of this research are outlined below: Dissimilar joints of AA5083 (RS) and AA7075 (AS) aluminum alloys are successfully fabricated using the FSW technique with optimized parameters. The friction stir welding process resulted in refined equiaxed grains in the NZ, leading to an increased microhardness in this region compared to the unprocessed base materials. The UTS of the FSW joint fabricated with optimized parameters is 80% of the AA7075 base metal, indicating good joint efficiency. Electrochemical tests revealed that the FSW process did not significantly reduce the corrosion resistance of the dissimilar welded joint, with corrosion potential and current density values comparable to the base metals. The heterogeneous microstructure of the weld zone, characterized by a combination of regions from both base alloys, led to microgalvanic cells that influenced the corrosion behavior of the dissimilar joint. The fabricated dissimilar weld exhibited better mechanical properties without compromising the corrosion resistance in the chloride environments. Declarations Data availability : Data sets generated during the current study are available from the corresponding author upon reasonable request. Conflict of interest: On behalf of all authors, the corresponding author states that there is no conflict of interest. Ethical statement: The Author states that the research was conducted in accordance with ethical standards. Author's contribution: Meghavath Mothilal was the lead researcher and contributed significantly to all aspects of the work, including conceptualization, experimentation, data analysis, and manuscript presentation. Atul Kumar, as the research supervisor, provided academic guidance and critically reviewed the manuscript. Mahesh V.P. and Sandeep Rathee contributed to the paper background and assisted in parts of the experimental interpretation. All authors have read and approved the final manuscript and take responsibility for its content and integrity Funding: No funding was received for conducting this study. References Sinhmar S, Dwivedi DK (2024) Enhancement of the Mechanical and Corrosion Behaviour of FSW Joints Using a Novel Particle Reinforcement Approach. Trans Indian Inst Met 77:1053–1061. https://doi.org/10.1007/s12666-023-03160-4 Mehdi H, Mishra RS (2021) Effect of friction stir processing on mechanical properties and heat transfer of TIG welded joint of AA6061 and AA7075. 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Can Metall Q 62:244–261. https://doi.org/10.1080/00084433.2022.2120415 Satyanarayana MVNV, Kumar A, jain VKS et al (2023) Microstructure, mechanical properties and corrosion behavior of friction stir processed AA2014 alloy. Archives Civil Mech Eng 23. https://doi.org/10.1007/s43452-022-00565-8 Raturi M, Bhattacharya A (2023) Attributes of intergranular corrosion in AA6061-AA7075 double sided friction stir weld. Mater Chem Phys 298:127429. https://doi.org/10.1016/j.matchemphys.2023.127429 de Viveiros BVG, da Silva RMP, Donatus U, Costa I (2023) Welding and galvanic coupling effects on the electrochemical activity of dissimilar AA2050 and AA7050 aluminum alloys welded by Friction Stir Welding (FSW). Electrochim Acta 449:142196. https://doi.org/10.1016/j.electacta.2023.142196 Mothilal M, Kumar A (2024) Optimization of friction stir welding process parameter in the joining of AA7075-T6/AA5083-O dissimilar aluminum alloy using response surface methodology. Int J Press Vessels Pip 211:105282. https://doi.org/10.1016/j.ijpvp.2024.105282 Ashok J, Gupta AVSSKS (2024) Parametric effect on mechanical, microstructural and corrosion behaviour of friction stir welded AA5083-AA7075 alloys. Int J Interact Des Manuf (IJIDeM) 18:3849–3860. https://doi.org/10.1007/s12008-024-01850-x Mahesh VP, Kumar A, Arora A (2020) Microstructural Modification and Surface Hardness Improvement in Al-Mo Friction Stir Surface Composites. J Mater Eng Perform 29:5147–5157. https://doi.org/10.1007/s11665-020-05018-y Mirandola P, Novel D, Perini M et al (2024) Microstructures and mechanical properties of friction stir welded additively manufactured Scalmalloy®. Int J Adv Manuf Technol 134:1645–1660. https://doi.org/10.1007/s00170-024-14237-9 Jiang D, Kolupaev IN, Wang HF, Ge X (2025) Effect of tool diameter on the performance of 6061-T6 aluminum alloy in refill friction stir spot welding zone. Weld World. https://doi.org/10.1007/s40194-025-02008-3 Ghosh A, Sahu M, Singh PK et al (2019) Assessment of Mechanical Properties for Dissimilar Metal Welds: A Nondestructive Approach. J Mater Eng Perform 28:900–907. https://doi.org/10.1007/s11665-019-3867-3 Chen J, Chen R, Liao H et al (2024) Improving joint performance of friction stir welded 2195-O Al–Li alloy by post-weld heat treatment and rolling deformation. J Mater Res Technol 29:5048–5059. https://doi.org/10.1016/j.jmrt.2024.03.009 Prasad GS, Srinivasa Rao K, Madhusudhan Reddy G (2022) The effect of microstructure on corrosion behaviour and mechanical properties of friction stir welds of AA2519 and AA2219 Al-alloys. Mater Today Commun 33. https://doi.org/10.1016/j.mtcomm.2022.104446 You H, Kang M, Yi S et al (2021) Comprehensive Analysis of the Microstructure and Mechanical Properties of Friction-Stir-Welded Low-Carbon High-Strength Steels with Tensile Strengths Ranging from 590 MPa to 1.5 GPa. Appl Sci 11:5728. https://doi.org/10.3390/app11125728 Prabhakaran V, Strange L, Kalsar R et al (2023) Investigating electrochemical corrosion at Mg alloy-steel joint interface using scanning electrochemical cell impedance microscopy (SECCIM). Sci Rep 13:13250. https://doi.org/10.1038/s41598-023-39961-2 Ikeuba AI (2023) Bimetallic corrosion evaluation of the π-Al8Mg3FeSi6 phase/Al couple in acidic, neutral and alkaline aqueous solutions using the scanning vibrating electrode technique. Electrochim Acta 449:142240. https://doi.org/10.1016/j.electacta.2023.142240 Mroczkowska KM, Antończak AJ, Gąsiorek J (2019) The Corrosion Resistance of Aluminum Alloy Modified by Laser Radiation. Coatings 9:672. https://doi.org/10.3390/coatings9100672 Soomro IA, Hassan A, Aftab U et al (2025) Investigation of stress corrosion cracking behavior of friction stir welded thick al 6061-t6 alloy plate. Weld World 69:299–309. https://doi.org/10.1007/s40194-024-01845-y Lipińska M, Kooijman A, Śnieżek L et al (2024) The Influence of Microstructure Evolution on the Mechanical and Electrochemical Properties of Dissimilar Welds from Aluminum Alloys Manufactured Via Friction Stir Welding. Metall Mater Trans A 55:4373–4390. https://doi.org/10.1007/s11661-024-07550-1 Ma Y, Dong H, Li P et al (2023) Galvanic corrosion of AA5052/304SS welded joint with Zn-based filler metal in marine engineering. Corros Sci 211:110912. https://doi.org/10.1016/j.corsci.2022.110912 Seo B, Song KH, Park K (2018) Corrosion Properties of Dissimilar Friction Stir Welded 6061 Aluminum and HT590 Steel. Met Mater Int 24:1232–1240. https://doi.org/10.1007/s12540-018-0135-2 Anantharam GS, Kuriachen B (2025) Experimental investigation on the slurry erosion and corrosion characteristics of friction stir welded AA5052 in the marine environment. Wear 205920. https://doi.org/10.1016/j.wear.2025.205920 Gupta S, Haridas RS, Agrawal P et al (2022) Influence of welding parameters on mechanical, microstructure, and corrosion behavior of friction stir welded Al 7017 alloy. Mater Sci Engineering: A 846:143303. https://doi.org/10.1016/j.msea.2022.143303 Ajay E, Prasad ADV, Rao AG, Raja VS (2024) Role of microstructure on the varying corrosion behavior across the UNS S32750 super duplex stainless steel friction stir weld. J Mater Sci. https://doi.org/10.1007/s10853-024-10501-1 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. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6718161","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":465920715,"identity":"8d858143-a508-44d9-87c3-1b88b4eb577e","order_by":0,"name":"Meghavath Mothilal","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABF0lEQVRIiWNgGAWjYHACNjBpAMTMDAYWDHzsDSCuBUEtEkAtjM0MBhIMbDwHQFokiNXCANQikQAWwKlet7392oOfbXZ15mKHjz8uKJCQZ5N8fnXDjwIJBv727gRsWszOnCk37G1LlrCcnZbYPMNAwrBNOqfsZg/QYRJnzm7AquVGTpoEzxlmCYPbOYbNPAYSjEAtaTeADKB3crFruf8mTfLPmXq4Fvs2yTNpN//g03KD/Zg0T8VhuJbENgn2Y7fx2nImh01apuK45IbbaYmzgSqT23hy2G7LGEjw4PTL8ePPJN8YVPMb3E4+8Jnnj41tP/vxZzff/LGR42/vxaqFgYHHALsID3blIMD+gLDIKBgFo2AUjGwAANGJXxjb8IitAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0009-0000-3098-5590","institution":"Vellore Institute of Technology","correspondingAuthor":true,"prefix":"","firstName":"Meghavath","middleName":"","lastName":"Mothilal","suffix":""},{"id":465920716,"identity":"077e4987-fbfc-4b80-ba5e-0de91151292a","order_by":1,"name":"Atul Kumar","email":"","orcid":"","institution":"Vellore Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Atul","middleName":"","lastName":"Kumar","suffix":""},{"id":465920717,"identity":"7ec3a628-741a-4808-9f31-1602bbaf9fa2","order_by":2,"name":"Mahesh VP","email":"","orcid":"","institution":"Vellore Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Mahesh","middleName":"","lastName":"VP","suffix":""},{"id":465920718,"identity":"62da534b-336b-4c20-b696-e35d342ab15f","order_by":3,"name":"Sandeep Rathee","email":"","orcid":"","institution":"National Institute of Technology Srinagar","correspondingAuthor":false,"prefix":"","firstName":"Sandeep","middleName":"","lastName":"Rathee","suffix":""}],"badges":[],"createdAt":"2025-05-21 16:05:30","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6718161/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6718161/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":84036370,"identity":"c1ba44e6-7633-4449-bed5-d696d0becd2c","added_by":"auto","created_at":"2025-06-06 04:13:00","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":898679,"visible":true,"origin":"","legend":"\u003cp\u003eBase material optical images of dissimilar aluminum alloys (a) AA5083 (b) AA7075\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/e38209fade95aa6a66e2c136.png"},{"id":84036376,"identity":"a9fe8cbd-e29d-4258-adbd-7e564a1cf566","added_by":"auto","created_at":"2025-06-06 04:13:00","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":526394,"visible":true,"origin":"","legend":"\u003cp\u003eFSW experimental setup, along with the non-consumable rotating H13 tool\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/ace2f337ff5e9eb98c1a3a62.png"},{"id":84036778,"identity":"2f07774b-995a-4365-bb06-2ff3d35b4d4f","added_by":"auto","created_at":"2025-06-06 04:21:00","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":367681,"visible":true,"origin":"","legend":"\u003cp\u003eLeft side – Joining workpiece Fixture, and Right side – Solid state joining technique\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/61bd502138e180e42d5d1815.png"},{"id":84036382,"identity":"eb2ad622-27f1-4051-912e-7116c15fa615","added_by":"auto","created_at":"2025-06-06 04:13:00","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":787153,"visible":true,"origin":"","legend":"\u003cp\u003eMacrostructural analysis of a dissimilar Al alloy joint produced under optimized conditions.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/bd96d1c5379cc62928a5f6f1.png"},{"id":84036780,"identity":"f9fe1457-94ae-49c5-9475-f57b94fb9088","added_by":"auto","created_at":"2025-06-06 04:21:00","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":839295,"visible":true,"origin":"","legend":"\u003cp\u003eMicrostructure of aluminum alloys (a) AA7075 and (b) AA5083\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/47bb4b06519f885dc1534da3.png"},{"id":84036371,"identity":"ebd095a7-7771-4d2a-8cea-10d2ac77860d","added_by":"auto","created_at":"2025-06-06 04:13:00","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":38176,"visible":true,"origin":"","legend":"\u003cp\u003eMicrohardness vs distance from weld center.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/e2db47f21e6accbb86dc91d8.png"},{"id":84036386,"identity":"3a7459dc-4262-4842-8b9c-fdcdad533506","added_by":"auto","created_at":"2025-06-06 04:13:00","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":114774,"visible":true,"origin":"","legend":"\u003cp\u003eLeft: Tensile plot for optimized sample, right: Tensile sample as per ASTM-E8\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/f882d8fc5e2994b47edfcfa2.png"},{"id":84037344,"identity":"460e730c-8fb0-41a5-844e-70368804b7b0","added_by":"auto","created_at":"2025-06-06 04:29:00","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":79082,"visible":true,"origin":"","legend":"\u003cp\u003ePP curves for the WZ, B5, and B7 surface regions were obtained in a 3.5% NaCl electrolyte.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/caecc337cd649d46ca14b87c.png"},{"id":84036388,"identity":"99975cd7-913e-49ff-a837-57dab7bab340","added_by":"auto","created_at":"2025-06-06 04:13:00","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":77036,"visible":true,"origin":"","legend":"\u003cp\u003eNyquist plots from EIS measurements were generated for WZ, B7, and B5 surfaces in a 3.5% NaCl medium.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/f60b1c5b1b7cba142e6b5216.png"},{"id":84036380,"identity":"7272de18-d09d-4423-8e79-d2a61cedad9f","added_by":"auto","created_at":"2025-06-06 04:13:00","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":72830,"visible":true,"origin":"","legend":"\u003cp\u003eBode phase plots from the EIS analysis illustrate the electrochemical response of the WZ, B7, and B5 regions in a 3.5% NaCl solution.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/61cf3493deee1cc1f6587165.png"},{"id":84036389,"identity":"97af8b5d-0d71-475f-8a7e-d432de5fc82c","added_by":"auto","created_at":"2025-06-06 04:13:00","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":353397,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of with and without corrosion: (a) B5, (b) CB5, (c) WZ, (d) CWZ, (e) B7, (f) CB7\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/beedb903b208974cc6822de4.png"},{"id":85456043,"identity":"36b157df-9c86-4edc-9a03-4fcab7244daa","added_by":"auto","created_at":"2025-06-26 06:25:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5000367,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6718161/v1/0641857b-aa46-471d-8777-81bf8ad3c958.pdf"}],"financialInterests":"","formattedTitle":"Mechanical and electrochemical analysis of AA5083-AA7075 dissimilar alloy joints fabricated by friction stir welding","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAl alloys are generally utilized in an engineering field, mainly in the marine-related applications, owing to their superior strength and corrosion resistance [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Nonetheless, amalgamating these alloys with dissimilar characteristics, such as the high-strength 7xxx series and the corrosion-resistant 5xxx series, creates challenges for shipbuilding applications. Traditional fusion welding methods, such as gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW), frequently encounter efficiency issues due to the creation of brittle intermetallic compounds (IMCs) and porosity [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. FSW has been implemented to mitigate obstacles since it efficiently resolves issues like solidification cracking and porosity [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The Welding Institute (TWI) pioneered the development of FSW in the 1990s. FSW provides a unique approach for joining materials without the need to melt them [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. It employs a rotating H13 tool to produce heat via friction between the workpiece, resulting in the plastic mixing of the materials at the weld joint [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. This process arises at temperatures under the melting points of the workpieces, hence mitigating the emergence of undesirable phases and defects usually linked to traditional welding techniques [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. FSW has shown effectiveness in joining various aluminum alloys, resulting in enhanced mechanical properties and more excellent corrosion resistance compared to traditional welding methods [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eFSW leads to the creation of multiple zones: the heat-affected zone (HAZ), the thermomechanically affected zone (TMAZ), and the nugget zone (NZ). NZ is where the actual weld joint is created through plastic deformation and recrystallization[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Adjacent to NZ, TMAZ is present under the shoulder of the tool and undergoes plastic flow, while recrystallization does not occur [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Besides the TMAZ on the base material (BM) side, the HAZ experiences metallurgical changes due to the thermal gradient from the welding process [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The varying microstructure of the zones results in different due to various electrochemical, mechanical, and physical factors. Microstructure of the FSWed joint is influenced by several process parameters, which are rotational speed (R), welding speed (W), axial force (AF), tilt angle (T), the dwell phase (the period during the rotating tool remains idle after plunging), and tool design (TD) [\u003cspan additionalcitationids=\"CR17\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe study examined how the parameters and tool pin/probe profiles on the mechanical and microstructural properties of AA2219 Al alloys across the plate thickness. The study evaluated how varying FSW weld process parameters affected underwater welding, showing that a higher cooling rate improved the properties of the FSW joint. Additionally, another investigation indicated that the heat input during the welding process had a more significant effect on the residual stress and mechanical properties of a specific FSW weld joint than the deformation caused by the tool [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Variations in microstructural and mechanical characteristics were observed in dissimilar FSW (DFSW) weld joints of Al alloys because of different welding process conditions or parameters. Furthermore, the study revealed that the R-to-W ratio significantly influenced tensile and fatigue properties in the FSW of AA2198 Al-Li alloy [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe gel visualization methodology was used to examine how various FSW parameters affect the extent of the corrosion on the AA2024 plate [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. It was found that the R (rpm) had a significant impact on the corrosion susceptibility. Analyzing corrosion resistance at different areas within the NZ and throughout the thickness of the plate revealed that corrosion resistance has been decreased as the R (rpm) and W (mm/min) increased [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The optimal combinations of R and W were identified to achieve the best corrosion performance for plate AA5052 in the FSW joint [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Additionally, Finer grain structures were observed as the W increases, which enhanced corrosion resistance by establishing a protective coating within the FSW joint of AA6061 [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The corrosion resistance of DFSW weld joints was assessed under several welding parameters; it is shown that the joints with lower heat input demonstrated the best corrosion resistance [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. This research highlights the complex interplay between FSW parameters, microstructural changes, and the corrosion susceptibility of AA7075 [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. It specifically notes the negative influence of precipitation distribution and the size of the grain boundaries (GBs) on corrosion resistance. However, the use of secondary heating emerges as a promising technique to minimize corrosion tendencies in AA7075 welds by improving microstructural changes and modifying precipitation distribution [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eFurther research is needed to comprehend the metallurgical, materials properties and the corrosion resistance of FSWed joints. Presently, there is limited literature available in the field of corrosion, metallurgical and mechanical behavior of DFSW joints of AA5083-AA7075 Al alloys. Therefore, it is essential to examine the comprehensive study to ensure the reliability and corrosion resistance of the DFSW weld joint. This research seeks to assess how the FSWed zones influence the mechanical, metallurgical, and electrochemical behaviour of the joint through tensile testing, Vickers microhardness, macro and microstructure analysis, scanning electron microscopy (SEM), EIS, and Tafel testing.\u003c/p\u003e"},{"header":"2. Materials and methodology","content":"\u003cp\u003eAs received, base materials of AA7075 (B7) and AA5083 (B5) (Bharat Aerospace Metals Mumbai, India) were utilized for the FSW butt joint. They were prepared using a wire-cut electrical discharge machine (EDM) with Length x width x thickness\u0026thinsp;=\u0026thinsp;110 x 7 x 5 mm. The composition (wt.%) of AA7075 includes 5.29% Zn, 1.71% Cu, 2.46% Mg, 2.21% Cr, 0.06% Mn, 0.23% Fe, 0.20% Si, 0.03% Ti, and the remainder is aluminum. In contrast, AA5083\u0026apos;s composition consists of 0.25% Zn, 0.10% Cu, 4.50% Mg, 0.15% Cr, 0.40% Si, 0.50% Mn, 0.02% Ti, 0.40% Fe, and the remainder is aluminum [\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e]. Optical microscopy is used to analyze the microstructural characteristics of these base metals, as illustrated in Fig. 1. Contamination (dirt) on the surface of the plates was removed with the help of ethanol before starting the joining of the workpieces, and then the plates were clamped tightly on the fixture. These two Al-alloy plates (AA7075 and AA5083) were joined using an FSW machine with a non-consumable rotating cylindrical tapered threaded H13 steel tool, and the dimensions are represented in Fig. 2. The AA7075 was situated on the advancing side (AS), whereas the AA5083 was set on the retreating side (RS), as illustrated in Fig. 3.\u003c/p\u003e\n\u003cp\u003eAll the experiments were conducted at an optimized FSW process parameter of tool R 1100 rpm, T 2˚, and W 50 mm/min. The transverse joints were maintained at a right angle to the rolling direction of the BM. The micro and macrostructural specimens were cut into 10 mm x 10 mm to analyze. The specimen was polished with emery sheets of 220 to 2000 grit size. Then, cloth polishing was done with alumina to get a mirror-like surface for the analysis of macrostructure, microstructure, and corrosion. The specimen is etched with Keller\u0026apos;s reagent (composition) for 30 seconds to reveal the grain boundaries (GBs). Optical microscopy (Make: Olympus, Model: Olympus BX61) was utilized for the microstructural analysis. The SEM (Model - Carl Zeiss, Make - Evo 18 Research). The microhardness test was carried out by utilizing Vicker\u0026rsquo;s microhardness tester (Model: MMT X7B Make: Matsuzawa Co. Ltd.) on the traverse-section of dissimilar joined sample, as specified by ASTM E-384. The tensile samples were taken from the base plates and welded plates following the guidelines of ASTM E-8. The tensile testing was performed by a 100kN capacity UTM (Model: 8801, Make: Instron) to determine the UTS of the weld joint.\u003c/p\u003e\n\u003cp\u003eThe corrosion behavior of B7 and B5, as well as the weld zone (WZ), was assessed using potentiodynamic polarization (PP) and EIS tests. Samples were polished to a mirror finish prior to testing to ensure surface quality. A 3.5% sodium chloride solution at room temperature was used for the corrosion tests. A standard 3-electrode setup was used, with a sample as the working electrode, a saturated calomel electrode as the reference, and platinum wire serving as the counter electrode. The PP test was conducted within the potential range \u0026minus;\u0026thinsp;1.5 V to +\u0026thinsp;1.5 V relative to the open-circuit voltage (OCV) at a scan rate of 1 mV/s. An open circuit delay (OCD) time of 1800 seconds was applied prior to the measurements. EIS was conducted over a 10 kHz to 0.01 Hz frequency range at the OCV with an AC amplitude of 10 millivolts (mV). Potentiodynamic polarization (Make: Ivium Potentiostat, Model: Vertex One) was used for the electrochemical studies, and the data was analyzed using the corresponding software.\u003c/p\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003e3.1. Macrostructure\u003c/h2\u003e\n \u003cp\u003eThe weld joint was created using the optimized process parameter and was examined using a stereo-zoom microscope to assess the development of specific zones within the weld. As represented in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e, the macrostructure reveals a clean weld interface free of cracks and defects, highlighting the effectiveness of the optimized FSW parameters in achieving sound joint quality. While material deformation is evident on the advancing and retreating sides of the weld due to the heat generated by a rotating tool, the macrostructure exhibits variations across the weld region [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e]. FSWed joints typically exhibit distinct zones, each characterized by unique microstructural features. When considering the DFSW joint, the stirred zone appears wider at the upper section due to the influence of the rotating shoulder. In contrast, the TMAZ, characterized by partially deformed and elongated grains, is also more pronounced on the top side. This heterogeneity in grain structure across the WZ significantly influences the mechanical integrity and corrosion performance of the joint [\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003e3.2. Microstructure\u003c/h2\u003e\n \u003cp\u003eThe metallographic samples (cross-section area in the traverse direction) were analyzed to study the microstructure of the optimized DFSW weld joint. Figure\u0026nbsp;5 shows different microstructures in the weld zones, such as HAZ, TMAZ, and the NZ. Delicate equiaxed grain structures are shown to develop within the NZ. This development occurs due to the dynamic recrystallization induced by thermal and mechanical conditions during the FSW process [\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e]. The material in that area experienced significant plastic deformation, producing refined smaller grains caused by the mechanical stirring effect of the rotating probe [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e]. Figure\u0026nbsp;5 illustrates the NZ on both sides of plate RS and plate AS. The grains adjacent to these boundaries appear elongated, while finer grains are located within the NZ. The fine-grained structure in the NZ enhances its strength, as demonstrated by the hardness measurements presented in the microhardness section [\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e]. Welding joints of various materials pose challenges due to their differing mechanical characteristics like, tensile, hardness, and metallurgical properties, such as microstructure and macrostructure [\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eBoth AA5083 and AA7075 show significant differences in grain deformation because of their distinct material properties. The TMAZ of plate RS exhibits the development of reveals the presence of smaller grains of irregular shape, as illustrated in Fig.\u0026nbsp;5 (b). In contrast, the TMAZ of AS (Fig.\u0026nbsp;5(a)) displays a banded grain structure at the NZ, causing the BM (Fig.\u0026nbsp;1(a)) to deform toward the NZ. As a result, grain deformation occurs in workpieces.\u003c/p\u003e\n \u003cp\u003eThe HAZ of AS exhibits enlarged grains due to the thermal influence from the NZ and the TMAZ of the same material. Furthermore, the AS of the weld experiences greater deformation and produces increased heat while stirring action in comparison to the RS of the weld. The HAZ of RS reveals a larger grain size than the BM (Fig.\u0026nbsp;1(b)) of the same, which primarily accounts for the weakened hardness and increased risk of failure relative to the NZ [\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n \u003ch2\u003e3.3. Microhardness:\u003c/h2\u003e\n \u003cp\u003eA microhardness test was done along their cross-section of dissimilar (AA5083 and AA7075) aluminum alloy samples using a 100-gf load applied for 15 seconds and measured at every 0.75 mm interval, in line with ASTM E-384. The findings in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e illustrate a distinct \u0026quot;W\u0026quot; shaped profile (bar chart), characteristic of FSW weld joints, and signaling microstructural variations across different zones. The highest microhardness value (189 HV) was recorded in the NZ, attributed to the refined grain structure formed through dynamic recrystallization during the friction stir welding process. Hardness consistently decreased from BM (B5-125 HV and B7-197 HV) to HAZ and increased from the HAZ to the NZ on both the AA5083 and AA7075 sides, indicating a finer grain size nearer to the weld centerline. This grain refinement process is driven by the intense thermo-mechanical conditions experienced by the material during the butt joint process. Notably, the HAZ of AA5083 exhibited lower hardness relative to other zones/regions, except for the BM of AA5083. This occurrence may be because of the presence of larger grains in this area, possibly caused by factors such as higher heat input or variations in material characteristics. The presence of these larger grains can act as potential sites for the initiation and propagation of fractures, which could compromise the mechanical integrity of the welded joint. This finding is supported by tensile test results, demonstrating the reduced strength of the HAZ (AA5083 (RS)). The effect of the FSW process on the microstructure evolution and mechanical response of the material is highlighted by the contrast in hardness between the NZ and the BM. The localized heat produced and distortion during the butt weld results in grain refinement and altered precipitation behavior, ultimately impacting the hardness and overall mechanical performance of the dissimilar butt weld [\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n \u003ch2\u003e3.4. Tensile testing\u003c/h2\u003e\n \u003cp\u003eThe tensile tests were conducted on the DFSW Al-alloys weld joints (AA7075-AA5083) using optimized FSW parameters: an R of 1100 rpm, a W of 50 mm/min, and a T of 2˚. Tensile samples were prepared following the standardized dimensions specified in ASTM E-8, as illustrated in Fig. 7. The fractures observed at a 45˚ to the loading direction predominantly occurred in the HAZ of AA5083 on the RS, indicating that this region is the weakest point in the weld. The improved tensile strength in the process, as mentioned above parameters, was confirmed and supported by the microhardness test. Consequently, the B7 strength is higher than that of the FSWed fractured specimen in the HAZ (RS), as shown in the stress vs. strain plot in Fig. 7. Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e illustrates the results obtained from the optimized and BMs tensile testing procedure.\u0026nbsp;\u003c/p\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eTensile strength comparison of base alloys with the welded sample\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMaterial\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eUTS (MPa)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAA7075 Base alloy (B7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e517\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAA5083 Base alloy (B5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e284\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAA7075-AA5083 Welded sample (WZ) at 1100 rpm (R), 50 mm/min (W), and 2˚ tilt angle (T)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e417\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cdiv class=\"gridtable\"\u003e\u003cbr\u003e\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003e3.5. Corrosion analysis of base materials and welded sample\u003c/h2\u003e\n \u003cp\u003eThe corrosion behavior of B7 and B5, along with the WZ joint, was studied using PP Tafel curves and EIS tests. Each sample\u0026apos;s corrosion potential (E\u003csub\u003ecorr\u003c/sub\u003e) was measured to evaluate its corrosion resistance. The BMs exhibited distinct corrosion behavior, with AA5083 showing better resistance due to the refined grains and the elimination of Al\u003csub\u003e3\u003c/sub\u003eMg\u003csub\u003e2\u003c/sub\u003e precipitates during FSW processing. Conversely, AA7075, enriched with Mg, Fe, and Si phases, demonstrated increased susceptibility to corrosion due to localized galvanic reactions initiated at Fe-enriched regions, as observed in Fig. 8. The E\u003csub\u003ecorr\u003c/sub\u003e difference is 200 mV between the BM, which highlights the potential for galvanic corrosion when dissimilar joints are formed [\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eFigure 8 shows the PP test outcomes, which are summarized in Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e. This table includes values for corrosion potential and Tafel slopes. The corrosion potential values are close to the open circuit potential (OCP) results presented in Fig. 8. Among the 3 locations, the corrosion current density for B7 is greater than that of the other two locations. The FSWed area displays a corrosion current density comparable to that of B5, which aligns with the fact that the FSW zone consists of material from B5, as illustrated in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e.\u0026nbsp;\u003c/p\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eData obtained through analysis of the PP curves are presented in Fig.\u0026nbsp;8.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWork materials\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003csub\u003eEcorr\u003c/sub\u003e (mV vs. SCE)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ei\u003csub\u003ecorr\u003c/sub\u003e (mA/cm\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026minus;\u0026thinsp;480\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.376\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWZ\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026minus;\u0026thinsp;730\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.322\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026minus;\u0026thinsp;680\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.549\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cp\u003eB5 has better corrosion resistance, as its corrosion current density value is lower compared to B7 and WZ. A higher corrosion current density value corresponds to lower corrosion resistance, and a higher corrosion potential value signifies better corrosion resistance [\u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e]. As per Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e, B5 has superior potential and lower current density values of corrosion, making it the best material among the three under discussion.\u003c/p\u003e\n \u003cp\u003eBMs\u0026apos; and DFSW\u0026apos;s joint corrosion behavior was extensively analyzed using EIS and PP tests. EIS tests using Nyquist and Bode plots revealed the distinct corrosion characteristics for the BM and the FSW joint, enabling the evaluation of their electrochemical stability in a corrosive environment [\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e]. In Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e, the Nyquist plots for B5, B7, and WZ samples exhibited the same shapes but were different in the magnitude of impedance, with larger semicircle diameters showing higher resistance. Lower corrosion resistance was observed in the FSW joint relative to the BMs; this is because of the galvanic coupling of dissimilar weld zones. However, sample B5 demonstrated better corrosion resistance than the tested samples of WZ and B7, as confirmed by both the PP and EIS results. These findings emphasize the impact of material composition, microstructural changes, and precipitation behavior on the corrosion performance of the FSW weld joints.\u003c/p\u003e\n \u003cp\u003eThe EIS data for the B7 and B5 exhibited significant differences in the impedance profiles, reflecting their different corrosion behavior. In Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e, the Nyquist plots for both materials displayed semicircles of various diameters, with B5 showing a larger semicircle than B7. This difference shows that the higher corrosion resistance in B5[\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e]. The enhanced performance of B5 is attributed to the dissolution of Al\u003csub\u003e3\u003c/sub\u003eMg\u003csub\u003e2\u003c/sub\u003e precipitates at higher temperatures, leading to a more refined grain structure and reduced susceptibility to localized corrosion. In contrast, the B7 alloy, enriched with Mg, Si, and Fe phases, exhibited lower impedance values. These phases act as active sites for corrosion, initiating galvanic cells within the aluminum matrix and accelerating the corrosion process [\u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eIn Fig. \u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e, the Bode plots further validated these observations, showing a higher modulus of impedance and phase angle for B5 across a wide frequency range. These parameters suggest a more stable passive film and greater resistance to charge transfer, contributing to B5\u0026apos;s superior corrosion resistance. On the other hand, B7 displayed a lower impedance magnitude, indicating a less protective oxide layer and higher susceptibility to localized attack [\u003cspan class=\"CitationRef\"\u003e46\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe DFSW joint of AA7075 and AA5083 exhibited a complex impedance response due to the heterogeneity of the WZ. The Nyquist plots displayed a combination of semicircles that corresponded to the mixed regions of these two alloys. Notably, there was a reduction in the diameter of the semicircles compared to the BMs. This finding highlights the lower corrosion resistance of the friction stir welded joint, primarily due to the galvanic coupling between the regions enriched with AA7075 and those enriched with AA5083 within the WZ. The areas rich in AA7075 acted as cathodes, while those rich in AA5083 functioned as anodes, which facilitated the initiation of galvanic corrosion at the boundaries and its subsequent propagation into the AA5083-rich areas.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003e3.6. SEM Analysis\u003c/h2\u003e\n \u003cp\u003eThe results of the SEM examination indicate notable differences in the microstructural features and intermetallic compounds present in the BMs and WZ of Al alloy samples that are either affected by corrosion or not. Samples B5 and B7 showed a consistent microstructure with few intermetallic precipitates in the base material regions. In contrast, the WZ samples exhibited a more varied microstructure, marked by a finer grain structure in the nugget area and partially deformed grains in the thermomechanically affected zone (TMAZ) [\u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e] as shown in Fig.\u0026nbsp;5.\u003c/p\u003e\n \u003cp\u003eElectrochemical corrosion tests showed that the samples containing corrosion base materials (CB5 and CB7) had lower corrosion resistance compared to the samples without corrosion (B5 and B7). This reduction in resistance is attributed to a higher presence of intermetallic compounds and second-phase precipitates, which provide favorable sites for the initiation of corrosion.\u003c/p\u003e\n \u003cp\u003eThe corroded weld zone (CWZ) specimen displayed the lowest corrosion resistance when compared to the non-corroded samples. This can be associated with the complex and heterogeneous microstructural weld region, which consists of various microstructural features. These include the fine-grained nugget, partially deformed grains in the TMAZ, and the coarse-grained HAZ [\u003cspan class=\"CitationRef\"\u003e48\u003c/span\u003e]. The differences in microstructure create microgalvanic cells, which accelerate the corrosion process.\u003c/p\u003e\n \u003cp\u003eIn the dissimilar AA7075-AA5083 joint, the presence of blended regions resulted in distinct corrosion characteristics. The areas rich in AA7075 acted as cathodes in relation to AA5083, leading to the initiation of galvanic corrosion along the boundaries of AA7075 before spreading into the AA5083-enriched regions. This behavior is particularly evident in sample B7, which exhibited more pronounced corrosion damage compared to sample B5, which had fewer surface pits (see Fig.\u0026nbsp;11). The corrosion process eventually transitioned to a more uniform attack along the as-welded surface (Fig.\u0026nbsp;11), while widespread corrosion was observed throughout the weld zone (WZ) of the joint. Additionally, the iron-enriched regions within the Al matrix further aggravated the corrosion in these joints. EIS and PP tests provided consistent insights into the corrosion resistance of the materials [\u003cspan class=\"CitationRef\"\u003e49\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eA comprehensive investigation of the electrochemical characteristics of the friction stir welded joint between AA7075 and AA5083 and the base metals has been conducted. The principal outcomes of this research are outlined below:\u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eDissimilar joints of AA5083 (RS) and AA7075 (AS) aluminum alloys are successfully fabricated using the FSW technique with optimized parameters.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe friction stir welding process resulted in refined equiaxed grains in the NZ, leading to an increased microhardness in this region compared to the unprocessed base materials.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe UTS of the FSW joint fabricated with optimized parameters is 80% of the AA7075 base metal, indicating good joint efficiency.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eElectrochemical tests revealed that the FSW process did not significantly reduce the corrosion resistance of the dissimilar welded joint, with corrosion potential and current density values comparable to the base metals.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe heterogeneous microstructure of the weld zone, characterized by a combination of regions from both base alloys, led to microgalvanic cells that influenced the corrosion behavior of the dissimilar joint.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe fabricated dissimilar weld exhibited better mechanical properties without compromising the corrosion resistance in the chloride environments.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e: \u0026nbsp; Data sets generated during the current study are available from the corresponding author upon reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest:\u003c/strong\u003e On behalf of all authors, the corresponding author states that there is no conflict of interest.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical statement:\u0026nbsp;\u003c/strong\u003eThe Author states that the research was conducted in accordance with ethical standards.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor\u0026apos;s contribution:\u003c/strong\u003e \u003cstrong\u003eMeghavath Mothilal\u0026nbsp;\u003c/strong\u003ewas the lead researcher and contributed significantly to all aspects of the work, including conceptualization, experimentation, data analysis, and manuscript presentation. \u003cstrong\u003eAtul Kumar,\u0026nbsp;\u003c/strong\u003eas the research supervisor, provided academic guidance and critically reviewed the manuscript. \u003cstrong\u003eMahesh V.P.\u0026nbsp;\u003c/strong\u003eand \u003cstrong\u003eSandeep Rathee\u0026nbsp;\u003c/strong\u003econtributed to the paper background and assisted in parts of the experimental interpretation. All authors have read and approved the final manuscript and take responsibility for its content and integrity\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e No funding was received for conducting this study.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSinhmar S, Dwivedi DK (2024) Enhancement of the Mechanical and Corrosion Behaviour of FSW Joints Using a Novel Particle Reinforcement Approach. Trans Indian Inst Met 77:1053\u0026ndash;1061. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s12666-023-03160-4\u003c/span\u003e\u003cspan address=\"10.1007/s12666-023-03160-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMehdi H, Mishra RS (2021) Effect of friction stir processing on mechanical properties and heat transfer of TIG welded joint of AA6061 and AA7075. 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J Mater Sci. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10853-024-10501-1\u003c/span\u003e\u003cspan address=\"10.1007/s10853-024-10501-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"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":"Corrosion resistance, scanning electron microscopy, friction stir welding, microstructure, microhardness","lastPublishedDoi":"10.21203/rs.3.rs-6718161/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6718161/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study aims to enhance high strength (AA7075), high-corrosion resistant (AA5083) dissimilar joints of Aluminum (Al) alloys employing friction stir welding (FSW) technique for marine applications. The dissimilar weld of Al alloys was fabricated with standardized FSW process parameters (i.e., 1100 rpm of tool rotational speed, 2° tilt angle, and 50 mm/min of welding speed). Detailed analysis of weld characteristics, mechanical properties, and corrosion behaviour are carried out to establish the effectiveness of the FSW technique for dissimilar welding. The hardness profiles across the weld regions revealed a notable increase in hardness within the stir zone when compared to the base metals, which is attributed to the fine-grained microstructure produced during the FSW process. The optimized FSW joint's ultimate tensile strength (UTS) is 80% of the AA7075 base metal, indicating good joint efficiency. Microstructural analysis through optical microscopy and SEM provides insights into the grain structure and phase distribution within the weld zone. The stirred zone exhibits a refined equiaxed grain structure due to the effect of dynamic recrystallization during FSW. Corrosion behavior was assessed using Tafel plots and Electrochemical impedance spectroscopy (EIS). The Tafel plots illustrated that the welded joint exhibited a corrosion potential and current density comparable to that of the base metals, suggesting that the FSW process did not lower the corrosion resistance of the materials. EIS results provided further evidence of the weld's stability in corrosive environments, with impedance spectra indicating better corrosion resistance.\u003c/p\u003e","manuscriptTitle":"Mechanical and electrochemical analysis of AA5083-AA7075 dissimilar alloy joints fabricated by friction stir welding","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-06 04:12:55","doi":"10.21203/rs.3.rs-6718161/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":"daffddfd-2725-4f6d-8074-e73845dec132","owner":[],"postedDate":"June 6th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-10-16T14:53:20+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-06 04:12:55","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6718161","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6718161","identity":"rs-6718161","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}