Friction Stir Welding Process Research Articles

Mechanical, wear, fatigue, and water absorption behavior of proso millet husk derived biosilica reinforced nylon 6–6 composite thick plates for friction stir welding process

Mechanical, wear, fatigue, and water absorption behavior of proso millet husk derived biosilica reinforced nylon 6–6 composite thick plates for friction stir welding process

Characterization of non-steady-stage during friction stir welding

Friction stir welding (FSW) has been widely applied in joining lightweight metals such as aluminum alloys. Similar to traditional arc welding, FSW also experiences a non-steady-stage in the initial stage of welding. Regarding the characteristics of the non-steady-stage during the FSW process, there has been a lack of research by scholars in this area. In this work, the Coupled Eulerian-Lagrangian (CEL) method was employed to perform a numerical simulation of the FSW process. Combined with related experiments, it was discovered that the instability of temperature and axial force leads to the characteristic transition from tunnel defects to void defects during the non-steady-stage. Furthermore, the length of the non-steady-stage was found to be 30 mm, and its duration is influenced by the welding conditions. Tensile tests have confirmed that the welding quality of the remaining part, after removing the keyhole at the weld’s end, is reliable.

Morphological and plastic deformation study on impact strength of AA7075 and 316LSS in friction stir welding

The Impact of Friction stir Welding (FSW) in two dissimilar materials particularly in 316L Stainless Steel (SS) and AA7075 is very challenging due to its inherent properties when exposed to elevated temperature environment. The 316L SS is the grade generally used for deep drawing process of various SS applications. The Aluminum which generally provides the oxide formation when subjected to friction stir welding and develops the proper patter of stir zone in the heat affected environment. General preheating is required for SS before exposing it to the FSW process. The temperature might be of around 350˚ C is required for SS, so that the developmental of thermal gradient and weld quality between the two metals will achieve in proper pattern. As the Impact study will provides the aluminum and Stainless steels in the welded zone or Heat Affected Zone (HAZ) with different cracking and nucleation behavior. This phenomenon enhances the mechanical property in the Aluminum zone. After the various literature study, the FSW welded region of the metal provides improper pattern due to same start of welding at the mid of the dissimilar joints. In this phenomenon the FSW can start its process from the steel side of the joint and completing it to the Aluminum joint will reduces the growth of void and nucleate the agglomeration of oxides fromAA7075 to 316LSS.

Experimental investigation and optimization of nano Al2O3 mixed FSWed joint between AA2024-T351 and AA7075-T651 by response surface approach

Additive mixed friction stir welding can be an innovative and novel method for enhancing the friction stir welding process. Thus, this research aimed to investigate nano Al2O3 effects on the mechanical and microstructure of FSWed joints using Al alloys AA2024-T351/AA7075-T651. The experiments were performed based on response surface approach based CCD twenty run with varying three factors: tool rotational speed (A: 800–1,200 rpm), welding speed (B: 20–60 mm/min), tool plunge depth (C: 0.2–0.4 mm) and fixed volume percentages of Al2O3 nano-particles (8%). Mechanical performances such as tensile, yield, and hardness tests have been performed and microstructural properties have been analyzed through SEM and microscopy. The statistical analysis shows that the tensile strength can be significantly affected by rotational speed (A), welding speed (B), tool plunge depth (C), interaction (AB, BC, AC), and quadratic term A2, B2 in the FSW process; yield strength was influenced considerably by main, interaction, and quadratic terms; main factors and quadratic terms A2, B2 and C2 significantly influenced hardness values. The fracture test revealed that the joints with Al2O3-reinforced AA2024-T351/AA7075-T651 alloys were more ductile and less brittle. The optimal conditions for FSW, tool rotational at 1,146 rpm, weld speed at 60 mm/min, and 0.4 mm plunge depth were responsible for higher tensile strength of 169 MPa, yield strength of 145 MPa, and micro-hardness values of 89 HRB due to the uniform nano-particle dispersions and better material mixing.

A novel hybrid multi-criteria decision methodology for assessing tool materials in friction stir welding process

A novel hybrid multi-criteria decision methodology for assessing tool materials in friction stir welding process

Friction stir welding and processing of pipes: a status report on joining, materials, and industry applications

Purpose The purpose of this paper is to compile a comprehensive status report on pipes/piping networks across different industrial sectors, along with specifications of materials and sizes, and showcase welding avenues. It further extends to highlight the promising friction stir welding as a single solid-state pipe welding procedure. This paper will enable all piping, welding and friction stir welding stakeholders to identify scope for their engagement in a single window. Design/methodology/approach The paper is a review paper, and it is mainly structured around sections on materials, sizes and standards for pipes in different sectors and the current welding practice for joining pipe and pipe connections; on the process and principle of friction stir welding (FSW) for pipes; identification of main welding process parameters for the FSW of pipes; effects of process parameters; and a well-carved-out concluding summary. Findings A well-carved-out concluding summary of extracts from thoroughly studied research is presented in a structured way in which the avenues for the engagement of FSW are identified. Research limitations/implications The implications of the research are far-reaching. The FSW is currently expanding very fast in the welding of flat surfaces and has evolved into a vast number of variants because of its advantages and versatility. The application of FSW is coming up late but catching up fast, and as a late starter, the outcomes of such a review paper may support stake holders to expand the application of this process from pipe welding to pipe manufacturing, cladding and other high-end applications. Because the process is inherently inclined towards automation, its throughput rate is high and it does not need any consumables, the ultimate benefit can be passed on to the industry in terms of financial gains. Originality/value To the best of the authors’ knowledge, this is the only review exclusively for the friction stir welding of pipes with a well-organized piping specification detailed about industrial sectors. The current pipe welding practice in each sector has been presented, and the avenues for engaging FSW have been highlighted. The FSW pipe process parameters are characteristically distinguished from the conventional FSW, and the effects of the process parameters have been presented. The summary is concise yet comprehensive and organized in a structured manner.

The Effect of Welding Process Parameters on the nilon-6 Plate Friction Stir Welded Joint

Nylon-6 is one of the most extensively used engineering thermoplastics. Due to its durability, reduced weight, low coefficient of friction, and abrasion resistance, this polymer is an excellent substitute for various materials, including metals and rubber. Despite being those, nylon-6 materials are joined together utilizing multiple welding processes. The current work examined the viability of the friction stir welding (FSW) method on nylon 6 plates that were 4 mm thick to investigate the effect of tool diameter ratio and feed rate on nylon-6 sheets with the FSW method on the tensile properties of the joints. The 4 mm thickness of the nylon-6 plate was cut into the dimensions of 115 mm x 100 mm. The sliced plates were then joined through the FSW process using ST80-based tools with various parameters in the shoulder to pin diameter ratio (D/r ratio) of 10/3, 15/3, and 20/3 and feed rates (FR) of 4 mm/minute, 6 mm/minute, and 8 mm/minute at a rotational speed (RS) of 5800 RPM. Afterward, the weld joint is cut using water jet cutting according to the tensile testing standard ASTM D638 type IV. Following this, characterization of the speci-mens, including macrograph examination, hardness testing, and tensile testing, was carried out. The results show that the highest tensile strength was obtained at a tool diameter ratio of 10/3 mm with a feed rate of 6 mm/minute, with a tensile strength value of 19 MPa reaching up to circa 90% of joint efficiency. The strength of the welded joint then decreases as the diameter ratio of the tool increases with each feed rate. Some defects appeared at the higher tool diameter ratios welded joint, including incomplete fusion, flash, thinning, and lack of bonding. In conclusision the combination of a D/d ratio of 10/3 and a FR of 6 mm/min at RS 5800 RPM can provide the optimal conditions for a strong nylon-6 friction stir welded joint.

Experimental and Simulation Investigation on Fatigue Performance of H13 Steel Tools in Friction Stir Welding of Aluminum Alloys.

As the central component in friction stir welding, the design and manufacture of welding tools for aluminum alloys have garnered substantial attention. However, the understanding of tool reliability during the welding process, especially in terms of fatigue performance, remains unclear. This paper focuses on the welding of AA2219-T4 as a case study to elucidate the predominant failure mode of the tool during the friction stir welding (FSW) of aluminum alloys. Experimental methods, including FSW welding and fracture morphology analysis of the failed tool, coupled with numerical simulation, confirm that high-cycle mechanical fatigue fracture is the primary mode of the tool failure. Failures predominantly occur at the tool pin's root and the shoulder end face with scroll concave grooves. The experimental and simulation results exhibit a noteworthy agreement, validating the reliability of the simulation model. The FSW Arbitrary Lagrangian-Eulerian (ALE) model developed in this study analyzes stress distribution and variation under the thermo-mechanical coupling effect of the tool. It reveals that stress concentration resulting from structural changes in the tool is the primary driver of fatigue crack initiation. This is attributed to exposure to alternating cyclic stresses such as bending, tension, and torsion at the tool pin's root, manifesting as multiaxial composite mechanical fatigue. Among these stresses, bending alternating cyclic stress exerts the most significant influence. The paper employs the Tool Life module in DEFORM software to predict the fatigue life of the tool. Results indicate that reducing welding speed or increasing rotation speed can enhance the tool's fatigue life to some extent. The methodology proposed in this paper serves as a valuable reference for optimizing FSW structures or processes to enhance the fatigue performance of welding tools.

Investigation of The Weldability of PLA Plus Sheets with Different Infill Ratios by Friction Stir Welding

Although the joining processes of plastics are typically carried out through welding, adhesive bonding, or mechanical fastening elements, the production of complex and large parts often requires welding technology. In this study, the effect of part infill ratio (20%, 40%, 60%, 80%, and 100%) on the welding strength of 3D printed PLA Plus parts was evaluated through friction stir welding (FSW). Tensile tests and temperature measurements were carried out to examine the effects of friction stir welding process parameters (feed rate: 50 and 100 mm/min and rotational speed: 1000 and 1500 rpm) on the structure and mechanical properties of friction stir welding. Moreover, visual inspections were performed to detect defects in the weld zone. Compared to the PLA Plus samples given as reference according to the infill ratios, the highest welding strengths were obtained at 80%, 60% and 100% infill ratios (29.4 MPa, 17.47 MPa and 41.12 MPa and 112.38%, 97.48%, 87.04% efficiency, respectively). As a result, it was determined that at low infill ratios (20% and 40%), the weld quality was negatively affected, and a surface tunnel defect occurred in the weld zone. It has been determined that the weld quality in FSW is significantly affected by the temperature occurring during the process. The study has shown that parts printed at different infill ratios, especially on a 3D printer, can be combined with friction stir welding and that the efficiency of the welding process can be increased by optimizing the infill ratios.

RS/AS and nugget zone SEM analysis and mathematical equations for parameter optimization on friction stir welding tool

In order to find the ideal process parameters, the friction stir welding (FSW) production process is combined with mathematical optimisation techniques in the current thesis. In terms of optimisation, the goals (or objectives) are process- related in that they define or represent how the process behaves. The Welding Institute (TWI),UK introduced the FSW process, which has been enhanced in this study, as a relatively new welding technology in 1991. In conclusion, because the process is solid-state and does not involve melting, many of the problems of conventional fusing welding techniques may be avoided. In the FSW process, two work pieces are submerged in a spinning tool. As a result of friction and plastic dissipation, the temperature rises to the point where the material is sufficiently softened to be mixed together, forming a weld. Involving solid material ow, heat transmission, thermal softening, recrystallization, and the production of residual stresses, the process is multiphysics in nature.

Optimization of 2024-T3 Aluminum Alloy Friction Stir Welding Using Random Forest, XGBoost, and MLP Machine Learning Techniques.

This study optimized friction stir welding (FSW) parameters for 1.6 mm thick 2024T3 aluminum alloy sheets. A 3 × 3 factorial design was employed to explore tool rotation speeds (1100 to 1300 rpm) and welding speeds (140 to 180 mm/min). Static tensile tests revealed the joints' maximum strength at 87% relative to the base material. Hyperparameter optimization was conducted for machine learning (ML) models, including random forest and XGBoost, and multilayer perceptron artificial neural network (MLP-ANN) models, using grid search. Welding parameter optimization and extrapolation were then carried out, with final strength predictions analyzed using response surface methodology (RSM). The ML models achieved over 98% accuracy in parameter regression, demonstrating significant effectiveness in FSW process enhancement. Experimentally validated, optimized parameters resulted in an FSW joint efficiency of 93% relative to the base material. This outcome highlights the critical role of advanced analytical techniques in improving welding quality and efficiency.

Micro-adhesive wear and microhardness behavior of friction stir welded 2524-T3 aluminium alloy

Friction Stir Welding (FSW) emerges as a compelling solid-state welding technique for aluminium alloy components used as aircfrat materials. Despite being a solid-state process and mitigating numerous solidification challenges, it retains its thermomechanical nature, affecting the material's microstructure and, consequently, its mechanical properties. This concise communication sought to assess the impact of the FSW process on the micro-adhesive wear and microhardness properties of the 2524-T3 alloy. The results showed that the FSW process was executed successfully on 2524-T3 aluminium alloy plates as well as the great influence of intermetallic particles on hardness and micro-adhesive wear.

In Situ Study on Fracture Behavior of Thick‐Section Friction Stir‐Welded AA 5083 Alloy

Friction stir welding (FSW) produces a gradient microstructure with distinct metallurgical zones. The present study focuses on characterizing the fracture behavior during uniaxial loading across thick‐section FSW joint in nonheat‐treatable 5083 aluminum alloy. The hardness variation is linked to microstructural features across the weld zones through correlative microscopy. Notably, the heat‐affected zone (HAZ) exhibits a lower hardness of 75 HV, while the thermomechanically affected zone (TMAZ) and stir zones (SZ) display a hardness of around 79HV. A marginal difference in hardness in HAZ prompts strain localization in HAZ on the advancing side of the weld, resulting in offset in fracture from the SZ, which is captured through in situ monitoring of the tensile test. Further, the postdeformation analysis reveals crack propagation along the maximum shear stress plane due to the coalescence of microvoids resulting from the fracturing and debonding of second‐phase particles. Overall, this study provides valuable insight for optimizing the FSW process of AA 5083 alloy for thick‐section applications.

Optimization of Installation Position for Complex Space Curve Weldments in Robotic Friction Stir Welding Based on Dynamic Dual Particle Swarm Optimization

Robotic friction stir welding (RFSW), with its wide application range, ample working space, and task flexibility, has emerged as a vital development in friction stir welding (FSW) technology. However, the low stiffness of serial industrial robots can lead to end-effector deviations and vibrations during FSW tasks, adversely affecting the weld quality. This paper proposes a dynamic dual particle swarm optimization (DDPSO) algorithm through a new comprehensive stability index that considers both the stiffness and vibration stability of the robot to optimize the installation position of complex space curve weldments, thereby enhancing the robot’s stability during the FSW process. The algorithm employs two independent particle swarms for exploration and exploitation tasks and dynamically adjusts task allocation and particle numbers based on current results to fully utilize computational resources and enhance search efficiency. Compared to the standard particle swarm optimization (PSO) algorithm, the DDPSO approach demonstrated superior search capabilities and stability of optimization results. The maximum fitness value improved by 4.2%, the average value increased by 12.74%, and the concentration level of optimization results rose by 72.91% on average. The new optimization method pioneers fresh perspectives for optimizing the stability of RFSW, providing significant grounds for the process optimization and offline programming of complex spatial curve weldments.

Friction stir extrusion of thin AA 7075-T6 into low-carbon steel: Effects of low weld pitch value

Friction stir extrusion, a derivative process of friction stir welding, forms a mechanical joint between workpieces by forging one into a prefabricated geometry within the other. Thin sheet AA7075-T651 extrusion joints were made into an O-ring dovetail channel within a low-carbon steel workpiece. The effects of low weld pitch process parameters on joint characteristics between the extruded thin sheet AA7075-T651 and low-carbon steel were observed. The weld pitch was varied from 0.02 to 0.05 mm rev−1. No material mixing was observed. Tensile-shear test results were normalised by sample width. The 0.04 mm rev−1 weld pitch group yielded the highest average joint strength at 493 N mm−1. The weld pitch parameters reduced machine in-process forces without a large decrease in joint strength.

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 200ºC. 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.

Efficiency Improvement of Friction Stir Welding Parameters on AZ91 Magnesium Alloy Joints

Abstract: Friction Stir Welding (FSW) is a solid-state welding that permits an intensive formof parts and geometries to be welded with great nature of joints. The use of high-quality Magnesium alloys is extending in shipbuilding industry, particularly for the advancementof naval warships, cruise ships, littoral surface craft and merchant ships. FSW advancementhas been seemed to have various focal points for the exploitation of Magnesium alloys structures, as it is a minimal effort welding process. The objective is to come across the optimum levels of the process parameters in which it yields maximum tensile strength andbetter hardness. A three-factor, three-level design is utilized for optimizing the FSW process parameters and a Taguchi L9 orthogonal array experimental set up is used to anticipate the responses. The system parameters considered are Rotational speed, Transverse speed and the Tool tilt angle. The Friction stir welding is processed for butt joining of Magnesium alloys (AZ91) plates with 6 mm thickness. Tensile testing is attempted on dog-bone kind test specimen for Magnesium alloys. Analysis of Variance (ANOVA) has been used to analyze the effect of different parameters regarding the responses. The microstructural attributes of the welded segments, including base metal, heat affected zone (HAZ), Thermo Mechanically Affected Zone (TMAZ) and Stir Zone (SZ) are examined through Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis carried out to quantify the chemical element allocation at the weld interface. The observed optimum condition for Magnesium alloys (AZ91) is 560 rpm, 60 mm/min and 1 degree.

Modeling and simulation of friction stir welding process: A neural approach

Friction Stir Welding (FSW) stands out as a groundbreaking method in solid-state joining for aluminum alloys, presenting an innovative way to achieve joints of exceptional quality. This research delves into the application of FSW for bonding, focusing on plates that are 6mm thick and made from aluminum alloys Al6063, Al5083, and AL6061, aiming to produce a variety of FSW joints. To evaluate the quality of these joints, the study compares mechanical properties such as tensile strength, safe bending strength, and bending toughness necessary for achieving a 90° bend. The investigation leverages welding data to formulate a neural model, starting with using a conventional feedforward neural model (CFNM). It tackles the limitations of CFNM, including its intensive training requirements and the challenge of dealing with unknown configurations, by proposing a new, more adaptable neural network model known as FNNM. When comparing the two models, it becomes evident that CFNM is constrained by a root mean square error (RMSE) of 7-15%, whereas FNNM marks a significant improvement with a minimal RMSE of 1-3%. This indicates that FNNM improves accuracy and effectively navigates the complexities of modeling with unknown parameters. Through this study, insightful contributions are made to understanding FSW in joining aluminum alloys and developing an advanced neural model capable of predicting the outcomes of welding with greater precision.

Effect of Dispersing In Situ Al-Cu Intermetallic Compounds on Joint Strength in Friction Stir Welding of AA3003-H18 Sheets

In this study, friction stir welding (FSW) was employed to join AA3003-H18 sheets by incorporating in situ Al-Cu intermetallic compounds within the stir zone. The FSW process was carried out under three distinct conditions: (I) without applying powder, (II) by introducing Cu powder, and (III) by incorporating Cu-Al mixed powder (50 vol.% Cu, 50 vol.% Al). The powder was embedded into the gap between two sheets. Subsequently, two-pass FSW, involving both forward and backward movements, was conducted with a rotational speed of 1200 rpm and traverse speed of 100 mm/min across all three experimental conditions. In the second and third conditions, the formation of in situ intermetallic compounds occurred through a solid-state reaction between Cu particles and Al within the stir zone. Examination of the stir zone through optical and electron microscopic studies revealed that the utilization of Cu-Al mixed powder resulted in finer and more uniformly distributed Cu clusters and Al-Cu intermetallics than samples welded with Cu powder alone. Notably, the stir zone of samples incorporating Cu-Al mixed powder exhibited finely dispersed, completely gray Al-Cu intermetallic particles, whereas those with only Cu powder displayed predominantly coarse core-shell particles in the microstructure. The introduction of Cu-Al mixed powder during FSW resulted in a stir zone with an average hardness of 74 HB, showing a 14% increase compared to the cases where Cu powder alone was added (65 HB). Tensile tests, conducted in both transverse and longitudinal directions on the FSWed samples, did not exhibit a consistent trend across the three mentioned conditions. Transverse tensile strength consistently ranged between 107 and 110 MPa, with joint efficiency varying from 52% to 54%. However, the longitudinal tensile strength of the joint with added Cu-Al mixed powder (158 MPa) surpassed those welded with Cu powder alone (134 MPa).

Behavior of microstructure and mechanical properties in the stir zone of friction stir welded ME21 magnesium alloy

In this work, Friction Stir Welding (FSW) of magnesium alloy ME21 in a T-profile is performed with a relatively higher welding speed than usual in this material. The FSW process parameters, i.e., rotational speed and welding speed, are investigated focused within its inherent microstructural and mechanical properties on the stir zones of the welded joints. The concept of a Stribeck Curve in tribological systems, is transferred to FSW to explain the transition between insufficient and full plasticization of the material. The stir zone presented a strong grain refinement due to the activation of dynamic recrystallization along with a completely changed crystallographic texture and orientation due to FSW. The hardness is overall improved, while the ductility and tensile strength were reduced. The microstructure and texture in the stir zone were not strongly influenced by changes in the welding parameters.