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Magnesium (Mg) alloys are used more frequently as a replacement for heavier structural materials because of their advantageous specific strength and eco-friendly attributes. Their fusion welding is a difficult process, but the friction stir welding (FSW) offers a potential solution to these issues. In this study, a thermal analysis is carried out to obtain the temperature distribution and residual stresses related to FSW of different Mg-Al-Zn series Mg alloys under different processing conditions. The highest temperature recorded at the centre of the weld was 544.04°C, while the average von Mises stress during welding was 185.07 MPa. These values were achieved with a tool rotational speed of 1000 rpm, welding speed of 40 mm/min, and a tool shoulder diameter of 21 mm. The temperatures obtained through the numerical model were validated by comparing them with experimental data. During the experimental analysis, small cracks were observed at the centre of the welded joint, resulting from the formation of MgO. The welded joint exhibited a maximum tensile strength of 234.86 MPa, which is approximately 90% of the stronger AZ31 Mg alloy. [ABSTRACT FROM AUTHOR]

This study investigated the effects of laser energy density at different scanning speeds on the microstructure evolution, phase equilibrium, mechanical properties, and fracture modes of welds in dissimilar steel welded joints (Q345D and 20Mn2). The connection of dissimilar steel welded joints is achieved by using a laser synchronous powder feeding method. The microstructure and phase evolution of the joint were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Mechanical property testing was performed on the joint via a micro-Vickers hardness tester and an electronic testing machine, and the fracture surface morphology was observed via a scanning electron microscope. The results show that when the laser energy density is 1125 J/mm2, the fine cellular crystals, columnar crystals, and equiaxed crystal structures of the joint are more uniformly distributed. As the laser energy density increased, the transition of the Q345D side structure from cellular to columnar crystals and the transition of the 20Mn2 side structure from cellular to equiaxed crystals became more pronounced. Mechanical property testing revealed that an increase in the laser energy density can significantly improve the microhardness and tensile strength of a joint. However, a large amount of the Fe matrix from the 20Mn2 side permeates into the coating, making the mechanical properties of the dilution zone lower than those of the crystallization zone, and making it more prone to fracture on this side. The fracture analysis results show that the fracture mode has strong ductility, and the fracture mode is judged to be ductile fracture. [ABSTRACT FROM AUTHOR]

The objective of present research work is to study joint strength and corrosion behaviour of dissimilar Friction Stir Welding (FSW) of Al 7075 and Mg AZ31 alloys with Cd and Zn interlayer. The FSW process performed at rotational speed 1300 rev min–1 and travel speed 20 mm min−1. The comparative study of mechanical properties and corrosion behaviour of FSW with Cd and Zn interlayers has been attempted for the first time. The result shows that the maximum tensile strength of 129 MPa has been achieved for FSW with Cd interlayer as compared to 85 MPa in the case of FSW with Zn interlayer. The corrosion rate was found in order of FSW with Cd > FSWwith Zn > BM AZ31 > BM-7075. It has been concluded that FSW with Zn interlayer resulted in comparatively lower strength and better polarisation resistance than the FSW with Cd interlayer in 3.5 wt-% sodium chloride (NaCl) solution. [ABSTRACT FROM AUTHOR]

This article outlines the development and examination of the properties of an asymmetrical dissimilar metal joint produced using friction welding (FW). Friction welding involving dissimilar materials, specifically a 50 mm (length) × 45 mm (width) × 20-mm (thickness) electrolytic tough pitch copper (ETP-Cu) plate and a 12.5-mm-diameter SS304L rod, was carried out. The assessment of the asymmetrically welded components encompassed ultrasonic testing, high-pressure helium gas testing, leak testing, tensile testing, scanning electron microscopy, optical microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, hardness measurements, and elemental mapping via X-ray. Significantly, there was an observed increase in tensile strength, resulting in a joint efficiency of 86.50% compared to the ETP-Cu base material, following FW between an asymmetric ETP-Cu plate and SS304L rod. The study unveiled notable variations in the microstructure near the joint interface on the ETP-Cu material side. Intermetallic compounds, such as FeCu4 and Cu9Si phases, were detected within the reaction layer at the interface between ETP-Cu and SS304L, exhibiting a variable thickness ranging from 30 to 50 μm. [ABSTRACT FROM AUTHOR]

This study explores the dissimilar welding of nickel superalloy 59 with Fe-Ni superalloy 904 L using the Gas Tungsten Arc Welding with Hot Wire technique (HW-GTAW). The HW-GTAW process produced defect-free weldments with complete penetration, as confirmed by macroscopic analysis. Microstructural analysis using FESEM and EDS revealed fine equiaxed and columnar dendrites in the fusion zone and identified a secondary phase enriched with chromium. XRD analysis supported the presence of predominant austenitic phases and indicated the formation of Cr23C6-type carbide. The grain size of the weld joint, determined using the Gaussian method and Scherer formula, was 44.53 nm, slightly smaller than base metals. Microhardness tests revealed values ranging from 226 ± 5 HV 10 to 243 ± 5 HV 10, with the highest values observed in the deep cryogenic treatment (DCT). The Mo in the ERNiCrMo-13 filler and the effects of DCT, which promote grain refinement, are responsible for this increase in hardness. Residual stress measurements revealed a maximum tensile stress of 315 MPa along the longitudinal axis and a maximum compressive stress of 355 MPa along the transverse axis. DCT enhanced the weldment's tensile strength by up to 12% compared to as-welded samples, with a 6% increase compared to shallow cryogenic-treated (SCT) samples. Charpy impact testing indicated a value of 88 J in the fusion zone, which is 1.2% less than alloy 59 and 9% higher than 904 L. Tensile fracture analysis revealed ductile dimples, while impact fractography showed a mix of ductile dimples and brittle, glassy cleavage facets. [ABSTRACT FROM AUTHOR]

This study explores the influence of welding current, travel speed and gas flow rate on response parameters including ultimate tensile strength (UTS), percentage elongation (PE), microhardness (MH) and residual stress (RS) using face-centred central composite design (FCCCD). Dissimilar AA6061-T6 and AA7075-T6 plates were welded using an automated tungsten inert gas (TIG) process. Mathematical models were developed to predict the mechanical properties. High welding current or low travel speed enhanced the joint quality but raised residual stresses. At a welding current of 145 A, travel speed of 1.28 mm/s and gas flow rate of 18 l/min, the optimized UTS, PE, MH and RS were predicted to be 167.28 MPa, 10.25%, 69.61 HV and 65.49 MPa, respectively. Confirmation experiments were conducted to verify the model's practicality. The results indicate that travel speed has the greatest influence on the responses, followed by welding current, while the gas flow rate has the least effect. [ABSTRACT FROM AUTHOR]

The creep behaviour of dissimilar weld joint of 316LN SS-P91 steel when subjected to lower applied stresses (below 100 MPa) generally fails in a Type-IV pattern. The dissimilar weld joint was welded through shielded metal arc welding (SMAW) process with INCONEL as electrode, a nickel-based superalloy. An interrupted creep test was carried out at creep condition of 80 MPa −600 °C temperature. Interruption was done at two stages of creep, i.e. (a) mid of secondary and (b) start of tertiary. Microstructural evolution with respect to the hardness variation along various regions of P91 steel at interrupted and the failed specimen was done. A coarsening of hierarchical boundaries and M23C6 carbides was observed along HAZ region that has resulted with respect to time and temperature. [ABSTRACT FROM AUTHOR]

AbstractThis study investigates the dissimilar welding of Inconel 718 (IN 718) and austenitic stainless steel 304L (ASS 304L) using Gas Tungsten Arc Welding (GTAW) with Ni-based filler ERNiCr-3. IN 718 is valued for its high-temperature stability, oxidation, and corrosion resistance, while ASS 304L offers excellent ductility, formability, and corrosion resistance. The objective is to evaluate the impact of ERNiCr-3 on the weld’s metallurgical and mechanical attributes. The materials, prepared with U-groove edges, were optimized for manual multi-pass welding. Microstructural analysis revealed an austenitic matrix with dispersed Ti(CN) and NbC precipitates, enhancing strength through dispersion-strengthening mechanisms, with no solidification cracking due to Nb presence. FESEM/EDS and colour mapping identified elemental migration and stable carbide formation at the weld interfaces. Mechanical testing revealed uniform hardness within the weld zone and tensile resistance of 510 MPa, underscoring the robustness of ERNiCr-3 weld metal. These results indicate that ERNiCr-3 is highly effective for producing superior quality dissimilar welds amidst IN 718/ASS 304L, making it suitable for applications in elevated-temperature and mechanically demanding environments. [ABSTRACT FROM AUTHOR]

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Several potential benefits in joining thin, dissimilar and highly conductive metals in a solid-state environment make ultrasonic welding (USW) a popular method for building Li-ion battery packs. The USW method is highly complex and relies on multiple factors. In this study, aluminum (AA1100) and nickel (UNS N02200) dissimilar sheets were ultrasonically welded using various process parameters. Plastic deformation, microstructural development, and the corresponding mechanical characteristics of the joints were evaluated qualitatively and quantitatively. The joint strength and critical intensity factor values seemed to rise until the welding duration of 0.3 s, following which there was a subsequent drop in their values. Based on the mechanical analysis, it is observed that the optimal condition records an amplitude of 68 µm, a weld time of 0.3 s, and a clamping pressure of 0.24 MPa. It showed that the joint performance was significantly impacted by the plastic deformation and microstructural changes at the weld region. On the Al side, substantial plastic deformation was observed, and it was primarily attributed to the sonotrode knurls' penetration. The Al sheet's thickness was reduced by more than 40%. The microhardness readings at the welding region experienced diminution due to the acoustic softening effect. The cross-section and fracture surfaces of the Al/Ni weld exhibited several distinct microstructural characteristics, such as atomic diffusion, crimped interface, dimple pattern, and swirl pattern flow. Additionally, the diffusion zone is also investigated using X-ray diffraction analysis. These observations offer valuable insights for enhancing weld quality and controlling the overall welding process. [ABSTRACT FROM AUTHOR]

This review paper explores the impact of various weld cladding techniques, such as MIG and TIG, alongside innovative methods like Cold Metal Transfer (CMT), on enhancing the microstructure, corrosion resistance and mechanical properties of metals and alloys. Welding dissimilar metals with traditional methods presents challenges, but the CMT process, a modified version of MIG welding, addresses these with its rapid deposition rate, improved bead aesthetics and low thermal heat input. Robotic welding further enhances microstructural characteristics. Advancements in conventional TIG, MIG and CMT processes, including A-TIG, Keyhole-TIG, Pulsed MIG, Plasma-MIG, CMT Pulse and CMT Advanced, improve capabilities such as weld penetration, heat-affected zone width, weld finish, and defect reduction. This paper summarises how different welding techniques improve weld quality in terms of microstructure, electrochemical and mechanical properties. Additionally, it compares conventional welds and their variants to identify the best welding technology for Austenitic SS316 in marine environments. Highlighting the applications and benefits of weld cladding in industries like aerospace, shipbuilding and power generation, the paper underscores the significance of a comparative study on TIG, MIG and CMT weld cladding using Ni-Cr-Mo filler on SS316 base metal for optimal corrosion resistance and mechanical performance in marine settings. [ABSTRACT FROM AUTHOR]

In recent years, hybrid materials combining aluminum alloys and steels have gained popularity across various industries due to their lightweight design and superior mechanical properties. However, joining these dissimilar metals is challenging because conventional fusion welding often fails due to significant metallurgical differences, leading to poor weld quality and increased defect susceptibility. Friction stir welding (FSW) has emerged as a promising technique to address these issues. This article reviews recent advancements in FSW of aluminum alloy and steel components, focusing on aerospace, marine, and automotive applications. It examines the impact of FSW parameters on intermetallic compound development and dissimilar weld joint characteristics. Topics include interlayer applications, modified FSW procedures, and numerical simulations predicting flow behavior, temperature profiles, and residual stresses. The study aims to be a valuable resource for professionals and researchers seeking to improve the joining of high-performance materials in key industries. [ABSTRACT FROM AUTHOR]

A lightweight multi-material combination of steel and aluminium alloy is becoming a novel approach towards environmentally sustainable transport systems. However, the joining of steel/Al is difficult due to the formation of brittle and hard intermetallic compounds (IMC) at the interface. Hence, there is an immense need to critically review the metallurgical challenges of IMC formation for steel/Al dissimilar RSW and summarise its significance and current scenario for controlling IMC formation and growth. This article presents the review of past research works that focus on controlling the formation and growth of IMC for steel/Al dissimilar resistance spot welding during the last decade. It also includes IMC formation mechanism, advanced characterisation techniques, significance of IMC thickness and effect of process parameters on IMC formation. Fe2Al5 is the most brittle and dominant IMC formed at the interface, which affects the soundness of the welded joint. Application of third-party interlayer at the interface, directly or by an auxiliary process, is observed as an effective approach for controlling the growth of IMC. Though this interlayer does not prevent the formation of IMC, it will reduce the growth or brittleness of IMC by changing its chemical configuration. [ABSTRACT FROM AUTHOR]

The joining of aluminum alloys using fusion welding often leads to issues such as hot tears, porosity, distortion, and solidifying cracks. To address these challenges, solid-state welding processes like Friction Stir Welding (FSW) are preferable. This study investigates the FSW of dissimilar aluminum alloys AA 5083 and AA 6061-T6, employing Acoustic Emission (AE) techniques for real-time monitoring. FSW was conducted under conditions with no defects, pinhole defects, and piping defects. The resulting joints were evaluated for their mechanical properties and metallurgical characteristics. Microstructural analysis was performed using an optical microscope, revealing that the defect-free condition achieved the highest tensile strength of 256 MPa and superior hardness of 93 HV at the stir zone. Tensile failure commonly manifested within the heat-affected zone (HAZ) of AA 6061-T6, primarily due to grain enlargement and the impact of Mg2Si precipitates. Examination of the fractured regions via scanning electron microscopy revealed ductile-mode fractures featuring elongated dimples and microvoids. AE parameters such as hits, amplitude RMS, and energy were analyzed, demonstrating that defect-free welds had consistent AE signal patterns, while significant variations were observed in pinhole and piping defect conditions due to larger defect areas. The findings suggest that AE monitoring is effective in detecting and analyzing welding defects, providing valuable insights into the FSW process for dissimilar aluminum alloys. [ABSTRACT FROM AUTHOR]

In this study, 6061-Al and AZ31-Mg were successfully joined using the contact reaction brazing process without an interlayer under a pressure of 2 MPa and a vacuum of 1 Pa. The study examined the microstructure and mechanical properties of 6061/AZ31 joints, as well as the impact of process parameters including heating mode, cooling rate, heating temperature, and holding time on the joints. The results show that the 6061/AZ31 brazing seam can be divided into two zones: the liquid-phase solidification zone and the diffusion reaction zone. The liquid-phase solidification zone consists of the (α-Mg + Al12Mg17) eutectic organization and precipitation phases distributed therein. The diffusion reaction zone mainly consists of the Al3Mg2 layer in the brazing seam close to the 6061. Fractures in joints mainly occur in the diffusion reaction zone, where the hard and brittle Al3Mg2 layer is located and extends into the liquid-phase solidification zone. Brazing joint quality was better with a cooling rate of 5 °C/s and heating without pre-weld and post-weld holding processes. The highest joint shear strength of 37 MPa was achieved at 445 °C with a holding time of 5 s. The joint exhibited no obvious defects, and the axial shrinkage of the specimen was 0.414 mm, with minimal deformation. [ABSTRACT FROM AUTHOR]

Towards ensuring the structural integrity of the high-temperature components, it is essential to evaluate the creep crack growth (CCG) behaviour, especially for the weaker creep regions of the components. In this study, the CCG behaviour was investigated in the modified 9Cr-1Mo (P91) and Inconel (IN182) buttered layer interface regions of dissimilar metal weld (DMW) joints of P91 and type 316LN SS at 798 K and 898 K. For a quantitative assessment, the CCG rates were compared with the heat-affected zone (HAZ) of similar metal P91 welds (P91HAZ). The CCG rate was characterised using the creep fracture C* parameter as per ASTM E1457–17. The CCG rate in the P91/IN182 interface region was found to be higher than the P91HAZ, viz. 3.5 times and 4 times at 798 K and 898 K, respectively. This could be attributed to the propensity for creep cavitation in the interface region of the DMW joint. [ABSTRACT FROM AUTHOR]

In this study, a novel embedded machine learning (ML) framework was employed to analyze interfacial characteristics in dissimilar-alloy impact welding. While keeping the substrates constant, i.e., stainless steel and Ti alloy, the influence of interlayer types on the resultant morphology of impact-welded bonds was also highlighted. The dataset was meticulously generated through numerical simulations, utilizing materials properties and processing parameters as primary inputs. These inputs were used to predict various interfacial features, including the extent of wave formation (L), specific welding zone area (S), average waveform amplitude (A), and maximum interface temperature (Tmax). Impressively, exceptional predictive capabilities were demonstrated by the ML model, with determination coefficients of 0.938, 0.924, 0.967, and 0.909 for S, L, A, and Tmax, respectively. Based on the results, strong dependencies between interfacial features and the weight functions of materials properties and processing parameters were unveiled. Intriguingly, as the weight function of materials properties for a specific output objective increased, a corresponding decrease in the weight function of processing parameter inputs was observed. These findings emphasize the complex connection between input parameters and output characteristics, revealing previously unexplored intricacies in the impact welding process, facilitated by our advanced ML methodology. [ABSTRACT FROM AUTHOR]

Polymer/metal hybrid lightweight structures are increasingly employed in automotive, aerospace and electronics industries. Friction stir welding (FSW) is applied for the effective welding of metals and thermoplastic materials. For the welding of dissimilar materials, due to the significant property differences, it is hard to achieve high strength welded joints with smooth appearance. In this article, the influence of pin length is studied by experiments for the friction stir lap welding (FSLW) of Al alloy and carbon-fiber-reinforced thermoplastic (CFRTP). Tensile tests, OM, SEM and EBSD are carried out to evaluate the welding performance. Results indicate that the joint with smooth surface topography is obtained at the pin length of 2.5 mm with a peak temperature of 250.3 °C and the CFRTP matrix PEI thermal decomposition temperature residence time of 47.6 s. From OM and SEM micro analysis, the width of the bonding area is 3.02 mm and a thin uniform interaction layer is formed in the joint. EBSD confirms that the Al alloy in the stirring zone is refined after recrystallization. It is difficult to form a stacked layered structure in the bottom of joint, so the property of the joint is improved. The tensile strength is 32.9 MPa, which is 63.1% of CFRTP. [ABSTRACT FROM AUTHOR]

Dissimilar joining between carbon fiber reinforced thermoplastic (CFRTP) and metal has attracted attention of transportation equipment industry for reduction of weight and cost by multi-material structure. Friction stir spot welding (FSSW) between anodized A5052 (AO-A5052) and carbon fiber reinforced thermoplastic (CFRTP) was investigated for the improvement of joining strength. Average tensile shear strength of AO-A5052/CFRTP joint was 2505 N and more than 500 N higher than that of untreated-A5052/CFRTP joint. In the AO-A5052/CFRTP joint, probe plunge induced cracks and microwrinkles in the anodic oxide layer on the weld surface. Matrix resin was immersed into the cracks and the microwrinkles underneath of the shoulder of the welding tool. Reinforced carbon fiber and matrix resin was immersed into large crack at the outer peripheral corner of probe. Thus, those increased the joining strength by mechanical anchoring effect. Thermal stress test and machining stress test were performed for revealing the mechanism of cracking of anodic oxide layer. Although thermal stress did not generate cracks in the anodic oxide layer, machining stress by probe plunge generated cracks in the anodic oxide layer. The generated cracks in anodic oxide layer underneath of the shoulder were distorted to the rotating direction of welding tool by the friction stirring. [ABSTRACT FROM AUTHOR]

The present work describes the effect of welding parameters and tool pin features during friction stir welding of dissimilar AA6082 and AA7050. Mechanical behaviour of dissimilar joints fabricated by using two distinct tool pin features, welding speed (WS), and rotary speed (RS) were compared for superior weld properties. All joints fabricated from tool having threaded cylindrical (TC) pin feature were defect-free, whereas welds fabricated by the plain cylindrical (PC) pin tool at 800 rpm RS using different WS were found defective. At the same RS and WS parameters combinations, the width of the softened region was found comparatively less in PC tool welds. The highest ultimate tensile strength (UTS) and elongation of 187.33 MPa and 7.55% were obtained for weld fabricated from TC tool at 180 mm.min−1 WS and 800 rpm RS. However, the highest yield strength (YS) value of 168.8 MPa was obtained for dissimilar joints produced using the PC tool at 180 mm.min−1 WS and 1600 rpm RS. The tensile specimens of defect-free dissimilar joints were fractured from respective minimum hardness locations in ductile mode. [ABSTRACT FROM AUTHOR]

Selective microwave hybrid heating (SMHH)-based joining technology was utilized to fabricate dissimilar joints between SS2205 and SS304. The joining process involved exposing the materials to a 2.45 GHz frequency and 900 W of power for 720 s under atmospheric conditions, with SS304 powder used as the filler material. SMHH principles were employed to melt and fuse the filler powder with the interfaces of the joining specimens. To assess the joint properties, various characterizations were conducted, including X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), microhardness and tensile testing. XRD revealed the presence of carbides and intermetallics in the joint region. SEM revealed that the complete melting of powdered particles with the joining interface resulted in good metallurgical bonding between the joining specimens. The Vicker's microhardness measured in the joint region was determined to be 515.2 HV, indicating a substantial increase as compared to the microhardness value of the joining specimens. The average measured ultimate tensile strength of dissimilar joints was 584.15 MPa, with an elongation of 20.27%. The SMHH-induced dissimilar welds between SS2205 and SS304 demonstrated promising microstructural and mechanical properties, indicating the effectiveness of this joining method in industrial applications. [ABSTRACT FROM AUTHOR]

The joining of different materials, particularly metals and polymers, is exceptionally challenging due to the necessity of producing lightweight hybrid structures in the automotive, aeronautics, and shipbuilding industries. In this research, an attempt was made to fabricate hybrid joints between aluminum alloy 5052-H32 and polycarbonate. The weld joint was made using friction stir spot welding. Response surface methodology was used to optimize the working process parameters. In addition, laser presurface treatment techniques were used to compare the joint's performance. The mechanical and metallurgical findings demonstrate that these welds were effectively bonded together. Chemical adhesion was found to be the bonding mechanism between these dissimilar materials. The maximum tensile shear value obtained was 19.02 MPa at a tool rotational speed (TRS) of 1381 rpm, dwell time (DT) of 10 sec, and plunge depth (PD) of 0.9 mm in friction stir spot welding. Interestingly, the maximum joint strength of 23.37 MPa was obtained with the influence of laser-based presurface treatment at the same optimized welding parameters. This technology offers a feasible alternative to mechanical fastening and adhesive bonding for structural applications. [ABSTRACT FROM AUTHOR]

Joining of stainless steel (SS) and Ti alloys offers lightweight, cost-efficient, and versatile part design options across various industries. This work incorporates Cu and Ni interlayers and compares the evolution of temperature, force, and microstructure, with and without interlayers. With these interlayers, SS321 underwent dynamic recrystallization-driven grain refinement, whereas SS321 grains coarsen without interlayers. Ti6Al4V consistently undergoes grain refinement. Interlayers impact elemental diffusion and intermetallic formation, replacing Fe–Ti intermetallics with Ni–Ti and Cu–Ti intermetallics in the interlayered joints. Additionally, in this study, interlayers reduce peak welding temperatures, resulting in higher forces for improved contact and enhanced joint strength. Joint strength increases by 30% with the Cu interlayer and 64% with the Ni interlayer. Tensile tests reveal brittle failures with intermetallics at the fracture sites. Notably, the Ni interlayer leads to failure at the Ti6Al4V–Ni interface, instead of SS321–Ti6Al4V interface. [ABSTRACT FROM AUTHOR]

In the current work, quadratic mathematical models at a 95% confidence level were developed to predict the optimum value of output responses such as the tensile strength, microhardness, and % strain of SiC particles-based friction stir welded composite joints of AA6061 and AA7075. Tool rotating speed, transverse speed, and volume percentage of SiC particles were considered as processing variables to multi-optimize the output responses using the desirability function in the Response surface methodology. ANOVA analysis was carried out to confirm the validity and adequacy of the developed model. The developed models showed that rotating speed is the most influential and transverse speed is the least influential variable. The highest tensile strength of 263 MPa, microhardness of 189 HV, and % strain of 29.4% was found at a rotating speed (RS) of 1200 rpm, transverse speed (TS) of 30 mm/min, and 10% volume percentage of SiC particles. The optimized processing variables, including transverse speed, rotating speed, and volume percentage of SiC particles, were found to be 32 mm/min, 1164 rpm, and 8.7%, respectively. The value of multi-optimized output responses, including tensile strength, % strain, and microhardness, was found to be 252 MPa, 26.7%, and 178 HV, respectively. [ABSTRACT FROM AUTHOR]

Under time-dependent creep deformation in metallic materials in the presence of a crack, the driving force is influenced at a distance in the presence of a zone (such as an interlayer, interface, hole, etc.) which deforms differently in reference configuration. This influence may increase or decrease the crack driving force based on the type of inhomogeneity (elastic, plastic, creep). The nature and extent of influence of material inhomogeneity are studied in this work with a configurational force-based rate of crack driving force definition for a crack in the presence of dissimilar metal weld zone, HAZ and second base metal. [ABSTRACT FROM AUTHOR]

The objective of this research work is to present the mechanism of rotary friction welding of two dissimilar steels (X70 steel and duplex stainless steel). The selected rotational speed was maintained during the welding process. The welded sample was characterized by optical microscopy and hardness measurements. The welding sequence was presented. The duration and the mechanism of different welding stages have been determined. Optical observation revealed distinct zones in the welded joint. The Vickers hardness profile showed the difference in hardness across the welded joint. [ABSTRACT FROM AUTHOR]

The primary aim of this study is to enhance our understanding of friction stir welding (FSW) at the atomic level. To accomplish this, we utilised molecular dynamics simulations to examine the nanoscale fusion welding of dissimilar metals, i.e. aluminium and copper, through the FSW method. Our particular focus was on how the rotation speed of the tool affects structural changes and defect evolution during the nanoscale FSW process. Our research findings revealed that the region subjected to frictional stirring undergoes a phase change as a result of extensive plastic deformation during the FSW operation. Notably, stacking faults and similar defects were predominantly observed on the advancing side as the tool rotated and moved into the friction stir zone. Further, investigation of atomic shear strain snapshots indicated that higher rotational speeds resulted in a broader and more scattered friction stir zone, requiring a longer recovery time compared to slower rotational speeds. Additionally, the changes in atomic concentration during FSW have been studied using displacement vectors, concentration profiles and diffusion coefficient parameters. We also conducted simulationbased tensile and shear deformation tests, which revealed that higher tool rotational speeds led to enhanced material interlocking, consequently improving the mechanical strength of the FSW joints. [ABSTRACT FROM AUTHOR]

Shielded metal arc welding (SMAW) is one of the most important processes of joining two metals or materials because of its high efficiency and low time requirement. This work studied the tensile strength of SMAW dissimilar mild steel (MS) and medium carbon steel (CS) with various process variables such as Welding Current (WC), Electrode Angle (EA), and Root Face (RF). The chosen variable ranges are WC of 140,180 and 200Amp, EA of 30,45 and 60 degrees and RF of 1,2 and 3 mm respectively to identify the important variables on Tensile strength (TS). Design of experiments (DOE) is executed as per Taguchi L9 OA for recognizing the optimal level of variables to accomplish maximum tensile strength. The experimental result is witnessed that the highest TS (201.38 MPa) is attained at sample-8 when WC −140 Amp, EA-45 degree and RF-1mm are maintained whereas the lowest TS (41.61 MPa) is obtained at sample-9 due to increment of the electrode angle (60 degree) and root face (2 mm), Analysis of variance result is revealed that Electrode Angle is the most important variable (73.97%) which improves TS of the SMAW joints, followed by Root face (6.24%) and Welding current (5.12%). [ABSTRACT FROM AUTHOR]

In this experimental study, ultrasonic metal welding (USMW) is introduced to join Al and SS thin sheets by varying surface conditions and weld energies. This research aims to enhance joint performance by properly controlling process parameters. Al/SS joints made at weld energy of 2550 J have the highest tensile shear and T-peel loads for the lubricated surface condition. The peak failure energy and critical stress intensity of the joints are also achieved under the aforementioned welding condition. With rising weld energy, the bond density increases and effective thickness decreases, revealing the increment in plastic deformation under the sonotrode knurls at the Al side. The upsurge in the microhardness values at the welding interface demonstrates the influence of natural aging and softening at the weld zone. Distinct mutual diffusion, wavy-like interface, dimple islands and swirl pattern flow appear at the Al/SS weld cross-section and fracture surfaces. [ABSTRACT FROM AUTHOR]

In the present day, the joining of dissimilar metals used in the same industry applications is of great interest. MIG and TIG welding processes are among the most common methods used to join dissimilar metals with high strength and reliability. Due to the different mechanical properties of dissimilar metals to be joined by these welding methods and welding parameters, they must be carefully selected. In this study, the effects of Total Accumulated Weld Volumes (TAWV) and different groove angles (45°, 60°, 75° and 90°) on the mechanical properties of AISI 1040 and AISI 8620 cylindrical steel joints were investigated experimentally. In addition, the fracture surfaces of the samples were examined by scanning electron microscopy (SEM) and energy dispersive X-ray (EDAX). In the process with MIG and TIG welding, only current and voltage changes were made in order to measure the effects of parameters on the mechanical properties of the joints more clearly. As a result of the studies, the highest average Ultimate Tensile Strength (UTS) was 579.611 MPa and the lowest average UTS value was 424.611 MPa. Based on TAWVs, the highest average UTS value was obtained in TIG welded joints, and the lowest average UTS value was obtained in MIG welded joints. It was observed that the UTS values of the joints were positively affected by the increase in TAWV. The UTS value of the 90° groove angled joint was found to be 40.25% higher than the UTS value of the 45° groove angled joint. [ABSTRACT FROM AUTHOR]

To evaluate the potential of similar and dissimilar welding, 3 mm thick plates of 5083 and 7039 aluminum alloys were joined by using the self-reactive friction stir welding technique. The bobbin tool was manufactured from H13 tool steel. The effect of several process parameters such as shoulder pinching gap, transverse speed, and tool rotation speed was investigated in order to design a defect-free joint. Tensile testing indicated that the joint efficiency for connections 5083–5083, 7039–7039, and 7039–5083, respectively, is 94.5, 80.4, and 97.4%. Which are much superior to the joint efficiency of fusion welding procedures and at least as good as, if not slightly better than, conventional friction stir welding. Microscopic investigation of the fracture surface of welded specimens indicated that ductile fracture is the primary failure mechanism for similar joints, whereas minor areas of brittle fracture can be seen for dissimilar joints. The hardness profile of the welded components' cross-sections near the upper and lower shoulders was investigated, and it was revealed that the higher hardness at the lower shoulder is due to the lower temperature of the workpiece in this area. [ABSTRACT FROM AUTHOR]

Al/Cu dissimilar welding is a key technology for weight reduction in fabricating high-functional products, however, conventional tungsten inert gas (TIG) welding is difficult to be applied due to a large fusion area. The constricted nozzle equipped inside the conventional TIG torch has been developed and can improve the position accuracy of tungsten electrode and arc plasma characteristics, moreover increase the heat input density. In this study, 0.5 mm-thick Al and Cu dissimilar sheets were butt welded using pulsed TIG welding with the constricted nozzle under two welding speed-current combinations of 50 mm/s-85 A and 100 mm/s-105 A. The 50 mm/s-85 A joint exhibited that Al and Cu mixed each other in the entire weld metal, containing two intermetallic compounds (IMC) of Al2Cu and Al4Cu9 mainly in the Al side. In contrast, both elements hardly mixed each other in the 100 mm/s-105 A weld metal and the interface exhibited hook-like shape at a nearly constant pitch, depending on the welding speed and pulse frequency. Consequently, the formation of IMC layers was limited. Based on the three-dimensional images reconstructed using a serial sectioning technique, the hook-shaped Al/Cu interface was also formed inside the weld metal. The mixed-zone volume per unit weld length of the 100 mm/s-105 A joint was estimated to be about 0.12 mm3/mm, and is much smaller than that of the 50 mm/s-85 A joint (0.97 mm3/mm). The average tensile strength of the 100 mm/s-105 A joint were higher than those of the 50 mm/s-85 A joint, suggesting that the hook-shaped Al/Cu interface together with the reduced mixed zone seems to increase the joint strength. [ABSTRACT FROM AUTHOR]

This paper characterises the dissimilar laser welding of 0.5 mm thick plate of shape memory alloy (NiTi) and copper (Cu) at different welding speeds. Properties of laser welds are characterised by microhardness testing, tensile-shear testing, XRD analysis, differential scanning calorimetry (DSC), and optical microscopy. XRD analysis of welded zone demonstrates the presence of NiTi, Cu, and equiatomic NiTi-Cu phases due to diffusion of NiTi and Cu at the interfacial zone of NiTi-Cu joint. DSC analysis shows the start and finish temperature of austenite phase during heating and martensitic phase during cooling for NiTi and laser welded sample. Microhardness studies reveal that weld zone possesses much higher hardness than NiTi and Cu base alloy. Microhardness value at NiTi-Cu joint interface (fusion zone) increases to 280HV and 150HV because of the presence of brittle and hard IMC phases (i.e. NiTiCu). The welded joints deliver higher joint strength than Cu base alloy but lower strength than NiTi SMA. Maximum joint strength of 335MPa (strain of 13.6%) is achieved at 1400W laser power and 1 m/min welding speed due to improved mixing and material flow. Microstructures of the fusion zone have dendrites grains and show the presence of Cu and NiTi constituents in the weld region. [ABSTRACT FROM AUTHOR]

Dissimilar materials welding between A6061 and SPC270 thin sheets was performed through friction stir lap welding and the effects of welding tool shape and clearance were investigated. The welding process was carried out on the 3-axis vertical machining center without tilt angle, using welding tools with flat or scroll shoulder surfaces. The highest tensile shear strength of 208.2 MPa using the flat shoulder was achieved under tool rotation speed of 2000 rpm and welding speed of 500 mm/min. Groove-like defects were found at the advancing side of this welding joint, which was thought to be caused by the deficiency of plastic material flow. Scroll shoulder improved the plastic material flow of aluminum alloys and weld surface without defects. However, cavities were formed in joints welding with a clearance of 0.1 mm near the interface between A6061 and SPC270. Reduction of clearance suppressed the formation of cavities and tensile shear strength of 217.9 MPa was achieved with the clearance of 0 mm. The welding interface was observed by SEM and TEM for microstructure investigation. Welding interface temperature during FSLW was measured and the factors for welding strength variation were also discussed in this paper. [ABSTRACT FROM AUTHOR]

As an alternative to fusion welding, FSW (Friction Stir Welding) is a unique solid-state welding technique that creates heat by friction between a non-consumable spinning tool and material substrate. The aluminium alloys (AA 2014 and AA 6082) have gained widespread recognition in the manufacture of light-weight structures. The mechanical and microstructural qualities of welded joints are appreciably influenced by welding process attributes namely tool spindle speed, pin geometry, and welding speed. The study centres on microstructural characterization and optimization means, mathematically developing a model to envisage tensile strength and micro hardness of dissimilar welds. Taguchi L9 orthogonal array with three factors and three levels was employed to carry out the experimentation. ANOVA and GRA (Grey Relational Analysis), dual technique based optimization approaches were used to signify the proposed mathematical model. For dissimilar joints, the best welding settings to optimize tensile strength and hardness were determined and presented here. [ABSTRACT FROM AUTHOR]

To obtain permanent joints from diversified parts and powder compositions, it is proposed to use discharge-pulse processes with the accumulation of stored energy in a capacitor bank. Technological difficulties in the manufacture of structures from non-ferrous metal and alloy parts of different thicknesses are listed. The thermal effect is carried out by passing the discharge current from the batteries of pulse capacitors, and the power effect is realized through the use of an inductive-dynamic drive. A scheme for the series connection of a compacted powder with an induction-dynamic drive, consisting of a flat inductor with a pusher, is proposed. The physical essence of the formation of compounds is described. The processes responsible for the formation of permanent connections by a pulsed current discharge have been identified. A picture of the relationship between the main parameters of the pressing process – sintering in time, as well as the results of measuring the temperature of the sintering process of powders by the photoemission method is presented. The results of energy consumption for the consolidation of powder compositions with simultaneous welding to a steel base are given. [ABSTRACT FROM AUTHOR]

The ability to integrate multiple distinct properties into a single structure is the driving force behind the development of NiTi to Ti6Al4V dissimilar joints. However, differences in thermophysical properties and the subsequent development of brittle Ti2Ni and Ni3Ti intermetallic compounds (IMCs) make fusion welding of these alloys rather challenging. The solidification of brittle IMC causes cracking upon solidification and a significant reduction on the joint mechanical properties. In this study, two strategies were used concurrently to reduce the formation of brittle IMC: zirconium (Zr) interlayer was introduced alongside with the laser beam being offset to the Ti6Al4V side. The influence on microstructural evolution was investigated using various characterization techniques. Scanning electron microscopy aided by energy dispersive spectroscopy and micro-X-ray diffraction supported by Rietveld refinement revealed that the volume fraction of the Ti2Ni brittle phase was drastically reduced from 90 to 9%, leading to improvements on the joint mechanical performance. A joint with a lower hardness of 392 HV was obtained, compared to 515 HV for the conventional NiTi/Ti6Al4V joint. The strength and ductility of the Zr-interlayered joint were improved to 320 MPa and 1.7%, respectively, compared to 148 MPa and 0.8% for the Zr-free joint. [ABSTRACT FROM AUTHOR]

Electromagnetic pulse welding technology shows a wide range of applications in welding dissimilar metals. In this work, the effect of the angle between the magnesium sheet rolling route and welding direction on the magnesium–aluminum joint has been studied. An electromagnetic pulse welding equipment WD-28 was used to weld the magnesium sheet and aluminum sheet. The angle was set to 0º, 45º, and 90º, and the discharge energy was set from 10.08 kJ to 17.92 kJ. The mechanical property of the magnesium–aluminum joints was compared. Scanning electron microscope and energy dispersive spectrometer were used to observe the microscopic morphology and element distribution of the bonding interface. Results show that the tensile strength of the joint is the highest when the angle is 0º under the same conditions. The tensile strength of the magnesium sheet, the movement of the collision point, and the metal jet during the electromagnetic pulse welding process were affected by the angle, causing the difference in the thickness of the diffusion layer, the morphology of the wavy interface, and the length of the welded zone. Moreover, the quality of the joints with different angles can be improved by increasing discharge energy. [ABSTRACT FROM AUTHOR]

Numerous industrial applications, particularly those in the transport industry, require the joining of dissimilar materials which offers considerable benefits in terms of low cost, design flexibility, and weight reduction for overall structures. The problems associated with conventional fusion welding processes have stimulated researchers in recent years to develop new joining methods for dissimilar materials which are particularly difficult to join. Friction stir welding (FSW) originally developed for joining difficult-to-weld Al-alloys and FSSW (a variant of FSW for spot welding) have exhibited great potential for obtaining sound joints in various dissimilar alloy systems in different configurations namely butt-, lap- and spot-welding, particularly in dissimilar Al-alloys systems with different properties, which are very difficult to weld using conventional fusion welding techniques. A major difficulty in joining dissimilar Al-alloys by FSW/FSSW lies in the discontinuity in mechanical and technological properties (such as high-temperature strength, plastic deformation capacity, viscosity, etc.) of the materials to be welded across the abutting surfaces. This discontinuity as well as inherent asymmetry in heat generation and material flow of FWS/FSSW processes causes a higher asymmetry in materials flow behavior in dissimilar welding. However, it is relatively easier to implement the FSW/FSSW process to dissimilar Al-alloys in contrast to FSW of dissimilar materials combinations with very differing properties, such as Al-alloy to Mg-alloy or Al-alloy to steel. [ABSTRACT FROM AUTHOR]

Dissimilar metals joining, especially Aluminum (Al) to copper (Cu), have gained importance in batteries for electric vehicles. Although friction stir spot welding (FSSW) has recently been used for welding dissimilar materials, progress has been very slow toward understanding the effect of temperature on diffusion condition between the two materials with the same FCC crystal structure. The thermo-mechanical modeling has been used to define the trajectory of Al and Cu particles at the weld interface, but it had a limitation to quantified the diffusion coefficient. Hence, the molecular dynamics (MD) study has been used to investigate the atomic interdiffusion of Al and Cu. The transmission electron microscopy results are used to validate the MD simulation outcome to understand the formation of dislocations and intermetallic compounds. The MD results implicated the formation of γ-phase (BCC), i.e., Al4Cu9 IMC toward the Cu side. Further, the In-situ investigation of non-FCC phase formation at FSSW condition has also been studied. [ABSTRACT FROM AUTHOR]

Dissimilar weld made of AA5083 and AA 7075 aluminium alloys using TIG welding (Current inthe range of 80120 amps) has investigated. Ultimate tensile strength of different weld joints fabricated at different current considered for assessing the joint quality. The results demonstrated that an optimum weld current of 100 amp yielded ~ 283 MPa tensile strength. Compositional analysis across weld pool has shown a signature of Mg vaporisation and Zn retention resulting in yielding high weld strength. The dilution curves of the Zn in 7075 side of TIG welded specimens show a gradual decrease in Zn fraction in HAZ leads to failure of tested samples along the HAZ side of AA7075. It has found that in the weld microstructure,there is a tendency in the weld zone for stabilising Mg by forming various intermetallic phases. [ABSTRACT FROM AUTHOR]

Welding of aluminium alloys to steels has been always challengeable. There are a certain number of methods to join these dissimilar metals all have their advantages and disadvantages. Advancement of any aluminium to steel welding strategies is an approach to control the size and nature of the intermetallic compound layer. A new method of electro spark microwelding has been developed for dissimilar welding of an aluminium alloy to steel to improve the joint mechanical properties. The microstructure of the welds are investigated by scanning transmission electron microscopy. The maximum tensile strength reached 206 MPa representing 65% of the tensile strength of the parent aluminium alloy with a ductile fracture locating at the fusion zone. The excellent bonding of the aluminium alloy and steel was based on the combined effects of the formation of about 4 μm thick nanoscale Fe rich intermetallic compound layer and complex mechanical inter-locking. The current research confirmed that aluminium could be successfully welded to steel via electro spark microwelding process. [ABSTRACT FROM AUTHOR]

Aluminium alloys and magnesium alloys offer superior properties with less density that allow designing structures with reduced cost, high efficiency, and material optimisation. Increasing usage of aluminium and magnesium alloys in industries like automobile, aerospace, railway, shipbuilding and marine requires their fabrication. At the same time, aluminium and magnesium joining is challenging due to detrimental effect of hard and brittle intermetallic compound (IMC) (Mg17Al12 and Mg2Al3) formation. Addition of interlayer or filler of chosen composition limit formation of Al/Mg IMCs by controlling IMC dispersal and variety (retarding amount of Al/Mg IMC and preferentially forming other less brittle IMCs). Fast welding processes; limit energy input and reactivity time to avoid IMC formation. Controlled heat input; maintain lower processing temperature to avoid IMC formation. These three individually or in combination are possible ways to tackle the formation of Al/Mg IMCs. Dissimilar Al-Mg joining by methods like Gas Tungsten Arc Welding , Diffusion Bonding, Laser Welding and Laser Weld Bonding, Cold Metal Transferand Friction Stir Welding have been discussed in detail. The effects of modification implemented on the material response in terms of resultant joint properties, microstructure and metallurgical relations are emphasised. Furthermore, the future scope for dissimilar Al/Mg welding has been deliberated. [ABSTRACT FROM AUTHOR]

One of the most significant requirements for joining dissimilar materials is to produce a minimum number of deeper-penetration welds and thereby avoid flaws. The Activated Flux TIG welding process improves penetration depth in a single pass, reducing the number of weldments. The dissimilar weld between LAFM – Stainless Steel 316LN also possesses the same requirement for a particular application. The present study aims to investigate the structure-property relationship and mechanical properties of dissimilar weldments of LAFM – SS 316LN using conventional TIG and Activated TIG welding using TiO2 and Co3O4 oxide fluxes. The microstructure study of conventional TIG weld reveals the fine lath martensitic structure as compared to weld prepared with A-TIG using TiO2 flux due to difference in the cooling rate. Also, the carbide formation in conventional TIG and A-TIG using TiO2 confirms the presence of delta ferrite But, the same observation was not confirmed with A-TIG weldments prepared using Co3O4. Similarly, the hardness results also support the microstructure study. The higher transverse tensile strength of weld indicates that it is stronger than base metal. The lower impact energy in case of Activated Flux TIG welding process was reported due to presence of oxide flux. [ABSTRACT FROM AUTHOR]

Crude fired heater furnaces in refineries are adopting P5 and P9 steel grades, depending on temperature and feed characteristics. Process conditions, however, are characterised by temperatures up to 600°C, well above the conventional creep threshold, which eventually cause a considerable over-tempering of the material. At the same time, crudes being processed have become more'critical' in terms of sulphur content and TAN (total acid number). THOR®115 steel grade designed by Tenaris already showed very good corrosion resistance against oxidation and sulphidation. In the present work, THOR®115 and P9 have been analysed and compared, considering their static and creep resistance, together with oxidation and corrosion rate occurring on the external and internal surfaces. The output of the benchmark, resulting in a better performance of THOR®115 rather than P9, has been used to develop an economical comparison between the two materials and quantify the advantage to adopt THOR®115 in furnace applications. [ABSTRACT FROM AUTHOR]

Welding of two dissimilar alloys of aluminium such as AA5082 and AA6061 using friction stir welding (FSW) and their weldability has been studied in terms of microstructural and mechanical characteristics of the formed joint. Assessment of tensile strength of the weld joint and microhardness in the weld zone and the thermo-mechanically affected zone were done. The joint showed a tensile strength of 0.253 kN/mm2 and a Rockwell hardness of 54 HRA. Optical microscopy was conducted to study microstructure in different areas on the joined workpieces. Neither cracking nor porosity was observed in the weld zone in several high-resolution optical examinations, implying that defect free zones seem to have formed with the process parameters used, i.e. at 1000 RPM and 30 mm/min. This indicates a very good compatibility in welding the two alloys. [ABSTRACT FROM AUTHOR]

In this paper, heat source model was developed for predicting temperature gradients and residual stress developing in welds of combined base materials AISI 309 L and Monel 400. The heat flux of 20.6 W/mm2, 28.9 W/mm2, and 35.8 W/mm2 were considered to perform the transient thermal analysis. A sequentially coupled transient thermo-mechanical analysis has been used to carry out numerical simulation with ANSYS 18.0 Workbench. Variation in the material properties with temperature was considered during FE preprocessing. The Poisson's ratio of Monel 400 and AISI 309 L metals was considered to remain same. Boundaries are subjected to conduction and convection loads. Radiation heat transfer is also considered in boundary conditions. The peak temperature and its distribution at different time locations were predicted from simulation results. Thermal stresses were predicted by performing structural analysis by taking thermal histories as inputs from thermal analysis. The thermal stress distribution was observed to be lower at welding current of 140 A and voltage of 14 V. The minimum longitudinal and transverse thermal stresses were observed as 282 MPa and 159 MPa respectively. Uniform and balanced thermal stresses were predicted in final pass welding simulation when compared to other two welding passes simulation. [ABSTRACT FROM AUTHOR]

Selection of suitable parameter range is essential in joining dissimilar combinations joints when more than one number of influencing parameters are present in giving desired output. This paper discusses on combination joints of AA6082 and AA7075 that were joined with ER4043 filler wire using suitable input parameters obtained from Taguchi's Method. The input parameters weld current, filler wire diameter and root gap were considered to design the experiments and output responses such as mechanical properties and bead geometry sizes were considered. For optimising the bead sizes and mechanical properties of weldments, an L9 array was used. Grey relational analysis was performed for optimising input parameters with multi-objective responses. ANOVA was performed to find the significance in effect of the welding parameters on dissimilar weldments. The analysis results of 8th trail was obtained as best performance set of values with main current at 210 A, filler wire diameter of 2.4 mm with a root gap at 2.0 mm. Results from ANOVA has shown that the welding current (36.75%) is affecting more on output responses followed by filler wire (35%) diameter and root gap (22%). Further, confirmation test was conducted for the optimum parameters and test results were validated. [ABSTRACT FROM AUTHOR]

During welding, the heat input is a critical parameter in determining the quality of the joints welded by any welding process. In the case of dissimilar welding, as dissimilar metals have significant differences in melting point, it is challenging to achieve an adequate joint. The emerging cold metal transfer welding process can resolve it effectively by controlling the heat while joining dissimilar metals. Therefore, in this research work, Aluminum-galvanized steel dissimilar joints were fabricated using varying heat inputs and their mechanical, metallurgical, and corrosion properties were evaluated. Furthermore, the second-phase formation at the weld interface has been investigated, and corrosion behavior is analyzed using electrochemical techniques in a 0.1% sodium chloride environment. The Tafel polarization and electrochemical impedance spectroscopy studies reveal it improved corrosion resistance due to an increase in heat input. The reduced solidification defects and the establishment of an appropriate intermetallic layer thickness with a suitable microstructure at the interface are the reasons for the improved corrosion resistance and strength of the dissimilar joints. [ABSTRACT FROM AUTHOR]

In manufacturing firms, welding technology plays a supreme role in joining purposes. The joining of dissimilar metals is complex in several conventional type welding. Friction stir spot welding (FSSW) is a solid-state welding technique and it is a derivative of conventional friction stir welding (FSW) to join the metals. The recent demands of advanced engineering materials such as aluminum alloys and stainless steel in the automobile sectors are forced to facilitate this research work, at the same time, the joining of such materials is quite complex because of its different welding characteristics. The main contribution of this work is to optimize and predict the microhardness and tensile failure properties of dissimilar metals by hybrid lightning search algorithm-simplex method (LSA-SM) and ANN algorithm. The dissimilarly joined metals namely, duplex stainless steel 32760 and aluminum 7075-T6 are utilized in this work and the experimentation is performed for six different test runs. Besides, the predicted values from the proposed algorithm are compared with the existing support vector machine (SVM) method. The predicted values of 314 Hv microhardness and 4967 N tensile shear failure load are optimized by the ANN-LSA-SM method at 1900 rpm. From the test results, it shows that the proposed model is efficient to predict the mechanical properties of the dissimilar welded materials than the experimental and SVM method. [ABSTRACT FROM AUTHOR]