Solid State Welding Process Research Articles

A comparative study of friction stir welding and friction stir scribe technique for dissimilar metal joining

Abstract Friction stir welding (FSW) has emerged as a novel method for joining similar and dissimilar ferrous and non-ferrous materials. This solid-state welding process utilizes frictional heat generated between a tool shoulder and the base material. The stirring action facilitates the movement and consolidation of the material, resulting in localized fusion and the formation of a joint. This review examines their effectiveness in joining various material combinations, with particular focus on automotive and aerospace applications. FSW utilizes frictional heat and stirring action to create localized plasticity and material flow, while FSS incorporates a cutting feature to mechanically interlock dissimilar materials. The review paper shows comparison of various experimental investigations considering variables such as tool geometry, welding parameters, and material combinations. FSW has some significant parameters to enhance weld quality such as traverse speed, plunge depth, and tool design. These techniques show promising applications for multi-material integration, offering advantages over conventional fusion welding methods. Future research directions include expanding material combinations, developing automated systems, and exploring hybrid joining approaches.

Insights into the microstructural evolution and strengthening mechanisms of friction stir spot welded advanced high strength ultrafine bainitic steel

Unlocking the full potential of advanced high-strength bainitic steels in spot-welding is a pivotal endeavor for harnessing their extraordinary mechanical properties in the automotive industry. This study suggests a shift in paradigm to address the inferior fusion weldability of this type of steel because of the formation of coarse martensite within the welded zone of weldments obtained by liquid-state welding, through the strategy of refining the martensite within the weld zone using the solid-state friction stir spot welding (FSSW) process. This paper delves into an in-depth investigation of the microstructural evolution and load-bearing capacity of a Fe-0.25C-3Cr-1.63Mn-1.5Si (wt%) ultrafine bainitic steel, having a remarkable tensile strength of 1.7 GPa, during the intriguing process of FSSW at rotational speeds of 600 to 2000 rpm. The research uncovers that the stir zone (SZ) undergoes dynamic recrystallization, resulting in a significantly refined microstructure. Regardless of the rotational speed employed, the high hardenability of the steel and rapid cooling during the process inevitably results in martensite formation within this region. However, a comprehensive microstructural characterization conducted by the electron backscatter diffraction (EBSD) analysis proves that the different thermal cycles induced by different rotational speeds lead into various prior austenite grain sizes, martensitic/bainitic packets and blocks attributes, and density of high-angle grain boundaries (HAGBs). Through the evaluation of strengthening mechanisms in different weld zones, the study sheds light on the key factors influencing strength. Block boundaries emerge as the primary contributor to SZ hardening, surpassing the role of geometrically necessary dislocations (GNDs) and solid solution strengthening. The load-bearing capacity observed during the tensile-shear test is governed by a delicate interplay between bonding width and crystallographic features (block size and HAGBs density) of the martensite formed within the SZ. The highest peak load was achieved under optimal welding conditions (rotational speed of 1000 rpm), which enabled the production of a sufficiently large bonding width, providing ample bonding area for load-bearing, along with an abundance of blocks and HAGBs to effectively impeding crack propagation.

Characteristics analysis and monitoring of friction stir welded dissimilar AA5083/AA6061-T6 using acoustic emission technique

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.

Comparison between Mechanical Properties and Joint Performance of AA 2024-T351 Aluminum Alloy Welded by Friction Stir Welding, Metal Inert Gas and Tungsten Inert Gas Processes.

The aim of this work is to study joining Al 2024-T3 alloy plates with different welding procedures. Aluminum alloy AA 2024-T351 is especially used in the aerospace industry. Aluminum plates are welded by the TIG and MIG fusion welding process, as well as by the solid-state welding process, friction stir welding (FSW), which has recently become very important in aluminum and alloy welding. For welding AA2024-T35 with MIG and TIG fusion processes, the filler material ER 4043-AlSi5 was chosen because of reduced cracking. Different methods were used to evaluate the quality of the produced joints, including macro- and microstructure evaluation, in addition to hardness and tensile tests. The ultimate tensile strength (UTS) of the FSW sample was found to be 80% higher than that of MIG and TIG samples. The average hardness value of the weld zone of metal for the MIG- and TIG-produced AA2024-T3511 butt joints showed a significant decrease compared to the hardness of the base metal AA2024-T351 by 50%, while for FSW joints, in the nugget zone, the hardness is about 10% lower relative to the base metal AA2024-T3511.

Tribological and mechanical properties of FSW joints of untainted stainless steel and titanium: novel characterization of similar and dissimilar joints

Friction Stir Welding (FSW) is an emerging solid-state welding process that joins dissimilar or similar metals based on requirements. The additional material to make the joint is also a weight reduction factor deemed vital in weight-sensitive industries like aerospace and orthopedic applications. The similar and dissimilar Ti-6Al-3Nb-2Zr-1Mo (Ti6321) and stainless steel (SS 310) joints are performed through friction stir welding. This investigation aims to identify the effect of process parameters on the mechanical behavior and microstructural characteristics of the FSW joints. Five plates are chosen; three are FSW joints, and two are kept in the original base material. In all five plates, tensile, microhardness, and wear tests are performed, including an analysis of grain size. It is observed that the similar Ti6321 joint with a 6 mm pin diameter, 60 mm transverse speed, 900 mm rotational speed, and a constant axial force of 1 KN exhibits a maximum microhardness of 362 HV and a tensile strength of 927 MPa when compared to other joints. The tribological properties are identified as varying load (10–50 N), sliding speed (1–5 m s−1), and a constant sliding distance (1000 m) on pin-on-disc apparatus. It reveals that welding parameters and tool diameter influence tribological characteristics. The surface morphology carried out by FE-SEM revealed that the HAZ is composed of acicular α. The increase in microhardness is higher in WC than in BM due to the uniform distribution of particles. The chemical composition and phases are analyzed using XRD.

Friction Stir Welding Benefits Technique over Other Welding Techniques of Dissimilar Metals

Abstract: Due to the low heat input situation, solid state welding (SSW) has demonstrated higher potential for integrating a variety of equivalent and dissimilar material combinations. The temperature stays below the melting point of the source materials throughout the solid-state welding process. Compared to fusion welding, solid state welding offers the highest quality. Aeronautics, nuclear, space, and aviation are just a few of the industrial production sectors that utilize the solid-state welding technology. Diffusion welding, explosion welding, friction welding, forge welding, cold welding, role welding, hot pressure welding, and ultrasonic welding are just a few of the SSW techniques covered in the current article. This study looks at a variety of SSW kinds and solid-state welding applications. This study examines many types of SSW and the applications of solid-state welding. Current Study includes the pros and cons of other welding techniques over friction stir welding.

Friction Stir Welding Benefits Technique over Other Welding Techniques of Dissimilar Metals

Abstract: Due to the low heat input situation, solid state welding (SSW) has demonstrated higher potential for integrating a variety of equivalent and dissimilar material combinations. The temperature stays below the melting point of the source materials throughout the solid-state welding process. Compared to fusion welding, solid state welding offers the highest quality. Aeronautics, nuclear, space, and aviation are just a few of the industrial production sectors that utilize the solid-state welding technology. Diffusion welding, explosion welding, friction welding, forge welding, cold welding, role welding, hot pressure welding, and ultrasonic welding are just a few of the SSW techniques covered in the current article. This study looks at a variety of SSW kinds and solid-state welding applications. This study examines many types of SSW and the applications of solid-state welding. Current Study includes the pros and cons of other welding techniques over friction stir welding

Effect of process parameters on weld geometry and mechanical properties in friction stir welding of AA2024 and AA7075 alloys

FSW joints are promising because they have a minimal heat input in welding and can limit the amount of intermetallic compound formation in dissimilar metals. Solid-state welding processes, particularly friction stir welding (FSW), are preferred for welding aluminium alloys due to their low heat input and ability to minimize intermetallic compound formation. This study conducted FSW trials on AA7075 and AA2024 alloys, each 4 mm thick. Parameters such as axial force, rotational speed, and traverse feed were adjusted while keeping other factors constant. The study analyzed weld geometry characteristics, including bead width and penetration depth. Angle distortions during FSW of thin plates in a butt joint were investigated. Additionally, the study examined the effects of FSW parameters on mechanical properties such as tensile strength and hardness immediately after welding. Microstructures of the welds were observed using optical microscopy (OM). The optimal mechanical properties are achieved at a rotational speed of 1000 rpm, a traverse feed of 30 mm/min, and an axial force of 10 kN. This optimal condition facilitates material flow around the pin at an ideal speed, ensuring adequate material filling and preventing tunnel formation. The stir zone's microstructure under these parameters exhibits a finely recrystallized structure with a significantly smaller grain size than the base material. Consequently, this enhances the joint's microhardness and tensile strength.

Investigation of the Effect of Heat Transfer during Friction Stir Welding (FSW) of AZ80A Mg Alloy Plates using a Pin Tool by Conducting Finite Elements Analysis

Friction stir welding (FSW) is an innovative solid-state welding process that has attracted substantial attention due to its potential for combining problematic materials such magnesium alloys, such as AZ80A. In order to better understand the impact of heat transport during FSW of AZ80A magnesium alloy plates using a pin tool, this study used finite element analysis (FEA). The welding process's thermal features, such as temperature distribution, thermal stresses, and material flow patterns, are the major focus of this analysis. The first step of the study is to conduct a comprehensive literature evaluation to lay a firm groundwork and pinpoint knowledge gaps. The thermal conductivity, specific heat, density, and mechanical characteristics of AZ80A magnesium alloy are measured and recorded as part of the material characterisation process. To ensure an exact simulation of real-world welding circumstances, a comprehensive 3D model of the welding setup is built, including the AZ80A magnesium alloy plates and the pin tool. In order to accurately record temperature variations, a tiny mesh is used, particularly in the welding zone. By include boundary conditions that mimic the real-world welding characteristics, such as the rotation of the pin tool and the clamping or fixturing of the plates, finite element analysis is used to model the FSW procedure. To simulate the heat input produced by FSW, a heat source or heat production model is used.

Friction Welding Processes: A Review

Friction welding is a sort of solid-state welding process that does not use flux, shielding gases, or filler metal; instead, the heat needed to fuse the materials is produced by the friction between two or more objects moving relative to one another. This kind of welding is an alternative to the traditional fusion and adhesive-based welding procedures. The method is reliable, capable of joining materials that would seem hard to join with traditional welding, and suitable for joining both similar and dissimilar materials including wood, steel, aluminum, copper, masurium, nickel, zinc and carbon steel. Friction welding can be carried out by using several techniques including linear, rotary, friction stir, direct drive and inertia welding. Each of these welding techniques is distinct and are named according to the relative motion involved. Although the process varies slightly subject to the type of motion, the procedure is consistent and the resultant joint is comparable with those obtained through conventional welding technique. This study reviews the distinct friction welding processes and specific techniques involved in the process.

Microstructure evolution and mechanical properties analysis in dissimilar ultrasonic metal welding of aluminum to copper

Ultrasonic metal welding is a solid-state welding process being widely employed for joining the interconnections of lithium-ion batteries in hybrid and plug-in hybrid vehicles. Examining the microstructure of the joint is of crucial importance to evaluate the performance. This analysis allows a comprehensive understanding of the phenomena influencing the joint strength. In this study, ultrasonic welding was utilized to join copper to aluminum sheets of 0.3 mm thickness, and then the macro- and microstructural characteristics of the weld cross-section and interface were thoroughly investigated. Finally, the microstructural changes at different values of ultrasonic welding parameters were correlated with the mechanical strength characteristics. This research identified mechanical interlocking and interface diffusion as the primary welding mechanisms. With an increase in welding time from 0.2 to 0.8 s, the bond density rose, the post-weld thickness decreased, and the average Vickers hardness at various points along the weld interface decreased by 10%.

Minimizing residual stress and fatigue crack propagation rate of FSW joints of AA2024-T3 by transient thermal tensioning: Effect of heater distance

Friction stir welding (FSW) is a solid-state welding process that is suitable for joining hardly weldable metals such as aircraft AA2024-T3 aluminum alloy. Despite FSW owns many advantages, however, some problems still arise, especially welding residual stress which influences the weld fatigue performance. In the present work, in-process transient thermal tensioning (TTT) treatment was applied to the FSW process of AA2024-T3 aluminum alloy by putting two symmetrical heaters at the sides of the weld line at distances of 25 mm, 40 mm, and 55 mm. The FSW was conducted at the tool rotational speed of 1500 rpm and tool traveling speed of 30 mm/min whereas the heating temperature was set at 200 °C. Subsequently, changes in microstructure, strength, hardness, residual stress, and fatigue crack propagation rate under TTT treatment were evaluated. The results showed that the use of TTT generated peaks of tensile residual stress along the heater passage which changed the residual stress distributions. It was found that the best fatigue crack propagation resistance of the weld occurred at the heater distance of 25 mm which was attributable to the compressive residual stresses present in the weld region induced by thermal tensioning combined with re-precipitation during welding.

State-of-the-art survey of literature for finding an effective solution to mitigate the exit-hole defect in friction stir welded samples

Friction stir welding is a solid-state welding process among the most important processes used for welding materials that the conventional welding process cannot weld. The joining of two metals occurs by heat generated due to the friction between the non-consuming rotating tool surface and workpiece. This technology is extensively used in the automobile, railway, maritime and aerospace industries. There are some defects that occurred in this process such as the tunnel, kissing bond, incomplete root penetration, excessive flash and void, those can be overcome by modifying the process parameters namely tool rotational speed, welding speed, downward force, shoulder diameter, shoulder geometry, tool pin geometry, tool pin diameter, tool pin length and tilt angle. The inevitable defect is the exit-hole left after the retraction of a rotating tool at the end of the weld cycle. The present work reviews different repair techniques for the exit-hole of the welded joints. This article discusses various exit-hole repairing techniques pertinent to the method, process parameters, material, plate thickness and the defect that emerges using these techniques. The current survey also presents a few future research opportunities in this field that can be carried out to mitigate the exit-hole defect.

Multi-objective optimization and experimental investigation of friction stir welding under Minimum quantity lubrication

Aluminium is widely used in the aerospace, marine, and transportation industries. However, achieving defect-free, high-quality welds using conventional welding processes is challenging. Friction stir welding (FSW) is a promising solid-state welding process that is environmentally friendly, produces high-quality welds, and improves the mechanical and other properties of aluminium and other lightweight materials. This study examines the welding force, power consumption, and surface roughness of friction stir-welded 6061-T651 and 5052-H32 aluminium alloys under similar and dissimilar circumstances using the minimum quantity lubrication (MQL) process. The main variables of the MQL system, including flow rate, nozzle orientation, and nozzle diameter, were analysed using analysis of variance. A multi-objective model was used to predict the optimal levels, and grey relational analysis techniques were applied for optimization. Furthermore, this study provides a clear mechanism for using MQL during FSW. The results indicate that a flow rate of 7.5 ml/h reduces welding forces by 25% and 4% compared to 5 ml/h and 10 ml/h, respectively. Additionally, the 7.5 ml/h flow rate reduces power consumption by 20% and 10% compared to 5 ml/h and 10 ml/h, respectively. In addition, it improves the surface quality. The orientation nozzle angle of 60° yielded slightly better results than those at the other levels. Similarly, for the nozzle diameter, both 2.5 mm and 3.75 mm showed slightly better results in terms of welding forces, power consumption, and surface roughness.

Bonding characteristics of aluminium laminates and aluminium–graphite composites processed by roll bonding

Roll bonding is a solid-state welding process, employed to join similar and dissimilar metals. Roll bonding with secondary particles in-between and accumulating the roll bonded material multiple times is an alternative method for manufacturing high-strength composites. In the current work, commercially pure aluminium strips are roll bonded at room temperature to 400 °C. The percent reduction varied from 10% to 70%, with an increment of 10%. Moreover, the aluminium strips are roll bonded with graphite particles dispersed in between (Al–Gr–Al). The aim is to study the effect of graphite particles on bonding behaviour. The critical process parameters such as the effect of temperature and percentage reduction on the bond strength are determined. The lap shear test is used to evaluate the bond strength. It is observed that the dispersion of graphite particles in between aluminium significantly increased the threshold reduction required for bond establishment. The threshold reduction decreases for roll-bonding aluminium with increasing temperature. Furthermore, it is observed that the bond strength significantly increases with increasing processing temperature. However, roll bonding with the graphite particles dispersed in between reduced the bond strength, and the effect was significant with increasing temperature. The bond strength of both Al and the Al–Gr–Al composites increases by increasing the reduction percentage. The de-bonded sample surfaces are analyzed using a scanning electron microscope. It is worth mentioning that the experimental outcomes of the current study predict the roll bonding parameters for the successful fabrication of an Al/Gr composite by accumulative roll bonding.

Short and Brief Review on Friction Stir Welding

Friction stir welding (FSW) has become the most popular welding technique for nonferrous alloys among researchers of the concerned field in the recent decade. It is a solid-state welding process and most suitable for nonferrous alloys, especially aluminium and magnesium alloys. Aluminium and magnesium alloys are the hot material for structural applications in transport vehicles, aerospace, and marine due to their lower densities and superior mechanical properties. Furthermore, FSW is associated with low temperature, which is responsible for eliminating defects of fusion welding such as porosity, liquation cracking, solidification, and cracking. This review article briefly introduces FSW and explains the different methods employed for FSW. Furthermore, process parameters, microstructural, mechanical properties, metallurgical investigations, advantages, disadvantages, applications, contemporary challenges and drawbacks, and future hotspots of FSW are identified.

Critical Review on Magnetically Impelled Arc Butt Welding: Challenges, Perspectives and Industrial Applications.

Magnetically Impelled Arc Butt (MIAB) welding is a cutting-edge joining method that replaces the conventional welding procedures such as resistance, friction, flash and butt welding. It is a solid-state process that uses a rotating arc to heat up the butt ends of tubes, being followed by a forging process that completes the joining of the workpieces The magnetic flux density and the current interact to develop the Lorentz force that impels the arc along the faying surfaces. This process is found to produce high tensile strength and defect-free welds in ferrous materials and for this reason, it is predominantly employed in automobile applications for joining metallic tubes. Also, this joining procedure can be applied in the fabrication of boilers, heat exchangers, furnace piping in petrochemical industry and other safety-critical high-pressure machinery parts. The MIAB method has several advantages such as a shorter welding cycle, lower input energy requirement and lower loss of material. Compared to other solid-state welding processes, the MIAB welding has an important advantage in terms of cost-efficient welds with better control and reliability. Moreover, there are researchers who have investigated the joining of non-ferrous dissimilar materials using this welding procedure. The studies have been focused on process parametric analysis that involves optimizing and forecasting the magnetic field and thermal profile distribution. This review article provides competitive insights into various design features, computational methods, tests and material characterization, technical issues and workarounds, as well as automation aspects related to the MIAB-welding process. This work will prove to be a quick reference for researchers, useful to identify the research gaps and conflicting ideas that can be further explored for advancements in joining the similar and dissimilar materials.

A Review on the Weldability of Additively Manufactured Aluminium Parts by Fusion and Solid-State Welding Processes

Additive manufacturing (AM) processes are playing a significant role in several industrial sectors such as construction and machine building industries, involving a wide variety of metallic materials. Among these, the AM of aluminium alloys has developed significantly over the last decade, mainly through Powder Bed Fusion (PBF) and Directed Energy Deposition (DED) processes. Despite the many advantages of AM technology, some large or complex products cannot be produced entirely without the use of conventional manufacturing and joining processes, generally for financial or operational reasons. In this way, the ability to join conventionally and additively manufactured components or parts represents a crucial step towards their future use and the consolidation of conventional and additive manufacturing technologies. Despite the growing interest in AM technologies, there is still a significant lack of information on the joining of conventionally and additively manufactured components. The present work proposes a first review of the literature evaluating the weldability of AM aluminium alloys. The focus is on the use of fusion and solid-state welding processes and analysing the achieved microstructural evolution and mechanical properties. A clear relationship is observed between the AM technology used to produce the part, and the physical principles of the joining process. In addition, the gaps in the literature are highlighted to enable focused future work.

AZ91 magnezyum alaşımlarının sürtünme karıstırma nokta kaynağı;eksenel kuvvet ve dönme hızının kaynak kalitesine etkisi ve muayene planlamasına ilişkin bir yaklaşım

In this study, the friction stir spot welding (FSSW) process for the magnesium alloy (AZ91) sheet materials are investigated. Friction stir spot welding (FSSW) is a solid-state welding process and one of the innovative methods to join specifically automotive components. Recently magnesium alloys are promising materials where combination of high strength and low density can be observed to improve vehicle performance and reduce emissions and fuel consumption in structural materials for automotive applications. A finite element model (FEM) established to understand the effect of axial force and rotational speed during the simulation in automotive applications. The FEM investigates the effect of axial force ranging from 1 kN to 8 kN and rotational speeds of 1000 rpm - 4000 rpm. The model analyses the heat flux and the temperature rise that leads defect formation after the process. 4.5 kN, 6 kN and 8 kN axial forces and 3000 rpm-4000 rpm rotational speeds are evaluated as the critical values in terms of defect and crack formation during the process under specified boundary conditions. Finally, several non-destructive inspection methods are suggested to secure structural integrity after the FSSW process to eliminate the harmful effects of surface and volumetric discontinuities.

Multi objective Optimizations of friction stir welding process parameters for reinforcement of copper particles in aluminum alloy using Taguchi based grey relational analysis (GRA) and ANOVA.

In this paper, optimize process parameters of friction stir welding for reinforcement of copper particulate in between aluminum alloys. It is to boost the thermal conductivity and mechanical properties of base metals. Two dissimilar aluminum alloys with different mechanical properties .AA6061-AA6063. successfully joined. In addition, the introducing copper particles of 325 mesh size in between aluminum alloy 6061 and 6063. It is a direct application of rotating non-consumable friction stir welding tool plunged for reinforcement. Introduction of a copper particle in between aluminum alloy is a unique system in the solid-state welding process. Taguchi method as an optimization tool used to design process parameters. Afterward, welding samples were cut in the desired size and progressed for a further test such as tensile and hardness test. Finally, it is observed to have improved mechanical strength in minimum spindle speed i.e.1000 rpm and welding speed 20 mm/min. Study also shows feasibility of GRA, Hypothesis .Z-test. test and ANOVA with Taguchi technique.