Friction Stir Welding Process Research Articles

Parametric study to investigate mechanical properties of welded dissimilar Al6063 and Al 7073 alloys through FSW process

Aluminium alloys have been the most prominent materials that have applications in every industry due to their high strength-to-weight ratio. The low melting point and easy recyclability also attract the scientific community to apply such material in modern manufacturing. The revolution in aluminium alloys came after the invention of friction stir welding, which provided high-end welding results and catastrophically increased its application in aerospace industries. Still, many inconclusive studies need to be explored for its high-end application, especially for newly invented aluminium alloy composites. Hence, this study investigates the application of friction stir welding process for welding dissimilar Aluminium alloy compositions. The investigation starts by analysing the effect of rotational speed, feed rate, and force on temperature generation, hardness, and welding strength. Three levels of process parameters, i.e. rotational speed in the range of 1000–1200 rpm, force of 12–18 N and feed rate of 40–60 mm min−1, are selected to analyse the effect on hardness and strength of the weld. After analysis, the optimum conditions obtained were a rotational speed of 1200 rpm, a feed rate of 50 mm min−1, and an average load of 15 N for a maximum hardness of 93.16 BHN and welding strength of 228 MPa. The investigation’s findings indicated that several phenomena, including the effects of high blending activity, plastic disfigurement, the repercussions of grain structure, and frictional intensity, may influence the hardness and strength of the weld. The growth of uniform structure at the stirred area is caused by pin movement during welding, specifically from the retreating side to the advancing side.

Numerical simulation and experimental investigation on friction stir welding of AZ31 magnesium alloy

Integrated numerical simulations and experimental investigations were employed to scrutinize the thermal, mechanical, and microstructural transformations of the AZ31 magnesium alloy during the friction stir welding (FSW) process. Especially, the primary focus was on the influence of process parameters such as rotational speed and welding speed on the temperature distribution, grain refinement, and mechanical properties of welded joints in alloys. By employing Deform-3D coupled with the integration of constitutive equations and dynamic recrystallization (DRX) models, the FSW process was investigated. The investigation revealed a significant increase in temperature when the tool’s shoulder made contact with the weld, resulting in the substantial accumulation of heat during FSW. Distinctions became apparent between the advancing side (AS) and the receding side (RS), with the AS exhibiting slightly elevated levels of temperature, equivalent stress, strain, and grain size. Specifically, adjustments in the rotational speed of the stirring tool and a reduction in welding speed resulted in larger grain sizes within the alloy. For example, when the rotational speed was set at 1200 rpm and the travel rate was 200 mm min−1, the initial grain size of the weld experienced a substantial decrease from 57.8 μm to 8.2 μm. Subsequent experimental verification, considering grain size and microhardness, was carried out to optimize FSW parameters for achieving the desired material properties. The accuracy of simulation results was validated through a meticulous comparison with experimental findings, underscoring the potential of numerical simulation in comprehending and predicting FSW processes.

Elucidating the influence mechanisms of splat cooling on microstructure evolution in friction stir welding of 2195 Al–Li alloy by multi-scale simulation

Al–Li alloy has been widely used in the manufacture of aerospace aircraft structural parts due to its high specific strength and excellent comprehensive performance. Friction stir welding (FSW), as a solid-state joining technique, generates comparatively lower heat generation in contrast to fusion welding. However, even with this reduced heat input, the welded joints of 2195 Al–Li alloy still exhibit noticeable thermal softening. FSW is very sensitive to welding heat input, and the thermal cycle of high peak temperature coarsens the grain in the weld zone, thereby reducing joint properties. To overcome these problems, external cooling can be applied to reduce peak temperature and increase cooling speed, improving the performance of FSW joints. In order to study the mechanism of external cooling on the microstructure evolution of joints, this work established a multi-scale simulation of splat cooling assisted friction stir welding (SCaFSW) of 2195 Al–Li alloy. The temperature change and material deformation data in SCaFSW were calculated in the macroscopic finite element model and used for further Monte Carlo microstructure evolution simulation, and compared with the conventional FSW process. Results reveal that the splat cooling significantly reduces the area of the high temperature region of the workpiece, decreasing the temperature at the same location 10 mm behind the tool by approximately 50 °C compared to FSW. While the local temperature field around the tool pin is not affected by the splat cooling, which mainly accelerates the cooling rate of the welded joint and reduces the plastic strain. In addition, the dislocation density in the weld nugget zone (WNZ) of SCaFSW joint is higher than that in conventional FSW, which promotes the process of grain nucleation and finally refines the grain in the WNZ. The simulated average grain size and thermal cycling results are in good agreement with the experimental results.

Multi-weld Quality Optimization of Friction Stir Welding for Aluminium Flange Using the Grey-based Taguchi Method

Friction stir welding (FSW) is gaining traction as a preferred technique due to its potential to reduce heat input and enhance the mechanical properties of welded joints. However, the path to commercializing FSW for flange joints is not without challenges. Two primary obstacles are the complexity of the welding path and the intricate design requirements for the fixtures. These factors contribute to the difficulty in determining the ideal weld settings and process parameters, which are critical for achieving optimal results. The current study addresses these challenges by applying FSW to flange joints using custom-engineered fixtures. These fixtures are meticulously designed to hold the pipes and plates securely during the welding process. The focus of the research is on optimizing the multi-performance characteristics of FSW for Al 6063 flange joints through the hybrid Grey-based Taguchi method. The integrity of the weld joint is assessed by examining various mechanical properties within the weld zone, including rotation speed, travel speed, tool profile, and shoulder diameter. The study identifies the optimal parameter settings for the FSW process: a rotation speed of 3000 rpm, a travel speed of 3 mm/min2, a shoulder diameter of 20 mm, and a conical tool profile. Under these ideal conditions, the welded material exhibited a tensile strength of 170.169 MPa, a hardness of 63.7709 HV, and a corrosion rate of 0.022 mm/year. These findings underscore the effectiveness of the optimized FSW process in producing robust and durable flange joints.

Analysis of variance and grey relational analysis application methods for the selection and optimization problem in 6061-T6 flange friction stir welding process parameters

A study was carried out to investigate and enhance the effects of friction stir welding on the mechanical characteristics of a flange composed of 6061-T3 aluminum alloy. The pipes possess an outer diameter and wall thickness of 6 mm, while the plates are sized at 100 x 100 × 6 mm. Nine unique experiments were planned using the Taguchi orthogonal array method, with the welding tool remaining constant. Three independent variables (travel speed, rotation speed, and shoulder diameter) were altered at three different levels for each variable. The research analyzed the influence of various FSW factors on the weld flange joint. Analysis of variance (ANOVA) and grey relational analysis (GRA) were employed to determine the impact of each FSW underwater parameter. Moreover, the statistical Taguchi technique (TM) was used to predict the optimal combination of welding parameters to improve tensile properties, including tensile strength (UTS), yield strength (YS), elongation (EI%), and bending load (BL) of welded joints. Additionally, the actual tests demonstrated a high level of agreement with the results obtained from the proposed mathematical model. The validation results obtained indicate that the optimization method is a dependable tool for enhancing the quality responses of friction stir welding.

A New Approach in Part Design for Friction Stir Welding of 3D-Printed Parts with Different Infill Ratios and Colors.

Parts produced using a 3D printer are combined with friction stir welding (FSW). In the FSW processing of parts with a low infill ratio, welding errors occur due to a lack of material. In this study, plates were created using two different-colored PLA Plus filaments with different infill ratios in the weld area (20%, 60%, and 100%). Triangular pin geometry, different feed rates (20, 40, and 60 mm/min), and different tool rotation speeds (1250, 1750, and 2250 rpm) were used as FSW process parameters. Tensile testing was performed to determine weld strength and hardness measurements, and visual inspections were performed. Color measurements were made on the test samples before and after the welding process, and the relationship between welding performance and color was evaluated. The best welding strength was obtained as 17.83 ± 0.68 MPa at a feed rate of 20 mm/min, a tool rotation speed of 1750 rpm, and a part with a 60% infill ratio in the welding zone. In the sample with the best weld strength, the temperature was measured as 198.97 °C. Color changes in the weld area of parts with 60% and 100% infill ratios were measured between 78.9-82.2 and 79.1-84.5, respectively. It was determined that the color change decreases as the weld strength increases in these parts. The results show that with the proposed new part design, the FSW method can be used at low infill ratios, and the weld strength can be evaluated based on the color changes in the weld zone.

A Review of Recent Improvements, Developments, Influential Parameters and Challenges in the Friction Stir Welding Process

Friction Stir Welding (FSW) is an innovative and reliable welding technique. Since this method is environmentally beneficial, it has received much attention and development over the past few decades. This study aims to revise the conceptual facts of FSW and evaluate the most recent improvements and developments in its applications. This review also assesses the influences of design parameters such as rotational and welding speeds on weld quality and joint efficiency. Existing challenges associated with applying FSW in various contexts, as well as the potential advantages that might lead to further study and broader FSW applications, are addressed. It has been concluded that FSW allows for optimising the rotating speed based on the preferred welding speed to achieve the greatest tensile strength in the welded materials. Despite FSW being established as effective in laboratory and small-scale applications, utilising FSW for large structures poses challenges. These challenges include maintaining consistent weld quality, controlling heat dissipation, and ensuring joint integrity during FSW. Consequently, further research is required to resolve these challenges and make FSW a promising welding method in contemporary production sectors.

Mechanical properties of base metal and heat-affected zone in friction-stir-welded AA6061-T6 at ultra-low temperature of 20 K

This study investigates the mechanical properties of a friction-stir-welded (FSW) AA6061-T6 aluminum alloy at ultra-low temperature (ULT) of 20 K. In-situ neutron diffraction and orientation imaging microscopy were employed to compare the tensile deformation behavior of the base metal (BM) and heat-affected zone (HAZ) in the FSW aluminum plate. The results demonstrate that compared to room-temperature (RT), ULT induces a significant improvement in tensile strength and ductility in both the BM and HAZ. The enhanced mechanical properties in BM at ULT result from a more homogeneous deformation than occurs at RT. On the other hand, HAZ at ULT exhibits an even lower yield strength than at RT, but the strain hardening rate (SHR) is the most significant among the alloys, leading to a tensile strength of 346 MPa and the highest ductility of 46.8%. The lowest yield strength corresponds to the lowest-hardness zones in HAZ, caused by dissolved/coarsened precipitates during the FSW process. The highest SHR in HAZ at ULT is attributed to the hardening of the {111} grain families and finer dislocation cell structures. The dislocation densities of both the BM and HAZ increased considerably during tensile deformation at ULT, which accounts for the improvement in tensile strength. Revealing the mechanism behind the remarkable improvement in the mechanical properties of FSW AA6061-T6 at ULT suggests its applicability for cryogenic applications.

Numerical Simulation of Friction Stir Welding of Dissimilar Al/Mg Alloys Using Coupled Level Set and Volume of Fluid Method.

The coupled level set and volume of fluid (CLSVOF) method is proposed to simulate the material distribution and physical properties during dissimilar aluminum/magnesium friction stir welding (FSW) process more accurately. Combined with a computational fluid dynamics model, the FSW process is numerically simulated and the heat transfer and material flow are analyzed. The results show that heat transfer and material flow have great influence on the Al/Mg bonding. In order to verify the accuracy of the model, the calculated results based on different methods are compared with the experimental results, and the Al/Mg interface simulated by the CLSVOF method is in better agreement with the experimental results. Finally, the material distribution and interface evolution near the tool at different times were studied based on the CLSVOF method.

Effect of tool rotational speeds on material flow and strain rates during friction stir butt welding of AA2219-T87 plates

ABSTRACT Friction stir welding (FSW) process is widely used for joining Al-Cu alloy (AA2219-T87) plates because of its high joint efficiency and low residual stresses in contrast to fusion-based joining techniques. A two-way coupled, 3D thermal-material flow model has been developed in COMSOL software, and the effect of tool rotational speeds on thermal and material flow fields, strain rates, thermal histories, and size of weld zones are being studied. The non-uniform net heat generation during the FSW process is due to the friction between workpiece and tool materials and the deformation energy of plasticized material flow sheared by the rotating tool. An approximate range of temperatures for the weld zones has been proposed and found to be appropriate because the predicted sizes are in good agreement with the experiments. Furthermore, the authors suggested that a quality FSW joint must have the nugget zone smaller and the heat-affected zone larger than the tool shoulder diameter.

Study on the microstructure and properties of spray formed 7055-T76 aluminum alloy joints by rotating magnetic field assisted friction stir welding

This study explores an electrically-magnetically-assisted friction stir welding (EMAFSW) method, conducting butt welding experiments on T76 tempered spray-formed 7055 aluminum alloy. Compared to traditional friction stir welding (FSW) processes, the EMAFSW method maintained basically consistent weld hardness, while tensile strength and elongation increased by 13.1% and 72.3%, respectively. The rotating magnetic field enhanced the mechanical stirring action of the welding tool, reduced the size of precipitates, promoted dislocation pinning, and increased the mobility of dislocations. The stirred zone (SZ) and thermo-mechanically affected zone (TMAZ) of EMAFSW weld joint showed significant grain refinement and increased recrystallization proportion, enhancing the weld joint toughness. The joint's fracture behavior shifted from brittle to ductile fracture.

Thermal and Mechanical Investigation of Friction Stir Welding with Disparate Materials AA6061 and AA7075

Background:: The primary objective of this study is to assess the impact of welding conditions on the mechanical properties of friction stir-welded butt joints created from two distinct aluminium alloys, namely, AA6061 and AA7075. Friction stir welding (FSW), known for its innovation and low-energy solid-state bonding technique, was employed in this research. Methods:: FSW experiments were carried out on both AA6061 and AA7075 alloys using a computer numerical control (CNC) machine. The selection and design of the tool geometry were meticulous, with an emphasis on new pin profiles that are nearly flat at the weld contact point. Precisely, four distinct tool geometries were machined from HC-HCr (High carbon, high chromium steel): Circular, Square, Tapered third, and Triangular. Critical process variables that significantly influence weld quality include rotation speed (800 rpm-1400 rpm) and traverse speed (12 to 25 mm/min). These variables were carefully optimized to achieve flawless welds. During the friction stir welding process, the nugget zone undergoes significant deformation, leading to the formation of a new microstructure that substantially impacts the mechanical properties of the joint. Results:: This study comprehensively investigates the thermal and mechanical properties of friction stir welding using aluminium alloys AA6061 and AA7075, considering various tool shapes. Among the four tool shapes employed, two were found to yield higher hardness values (referred to as BH). Notably, the square-shaped tool produced the highest temperature, reaching up to 690ºC, as determined by thermocouple readings. Based on the findings, the optimal FSW parameters for enhancing hardness involve an axial feed and spindle speed of 800 rpm combined with a feed rate of 15 mm/min. These parameters were identified as crucial for achieving the desired mechanical properties in the friction stir-welded joints. Conclusion:: This study presents new developments in FSW technology, which may have patent implications.

Progressive effect of dual-hybridization in friction stir welding by ultrasonic vibration and resistive heating for joining dissimilar material Al6063 aluminium alloy and C26000 copper alloy

In the world of disruptive technology, Al–Cu joints are quite in demand for electric vehicle batteries and other ion battery applications. Fusion welding is the less preferred method due to its many disadvantages; friction stir welding has the potential to become a sustainable process for producing a sound dissimilar Al–Cu joint. A study of multiple hybridization to the Friction Stir Welding (FSW)was made by utilizing two different energy sources of ultrasonic energy and electric current. The improvement is the property by different combination of the hybridization studied for utilizing the multiple hybridization technique to the FSW process for improving the weld efficacy and defects free weld even in case of dissimilar joints. Mechanical properties obtained by varying the process parameters have been studied and compared. Three process parameters have been selected including ultrasonic energy (10 KHz), electric current (75–125 Amps), rpm (400–600 rpm) and transverse tool rate (30–50 mm/min). A remarkable improvement in the mechanical property has been monitored by adding electric current to the UAFSW. Similar optimistic results in the improvement of the property have been found by adding Ultrasonic energy to RHFSW. The comparative study in the mechanical property had been presented to explain the improvement in the weld efficacy.

Active Vibration Avoidance Method for Variable Speed Welding in Robotic Friction Stir Welding Based on Constant Heat Input.

Robotic Friction Stir Welding (RFSW) technology integrates the advantages of friction stir welding and industrial robots, finding extensive applications and research in aerospace, shipbuilding, and new energy vehicles. However, the high-speed rotational process of friction stir welding combined with the low stiffness characteristics of serial industrial robots inevitably introduces vibrations during the welding process. This paper investigates the vibration patterns and impacts during the RFSW process and proposes an active vibration avoidance control method for variable speed welding based on constant heat input. This method utilizes a vibration feedback strategy that adjusts the spindle speed actively if the end-effector's vibration exceeds a threshold, thereby avoiding the modal frequencies of the robot at its current pose. Concurrently, it calculates and adjusts the welding speed of the robot according to the thermal equilibrium equation to maintain constant heat input. A simplified dynamic model of the RFSW robot was established, and the feasibility of this method was validated through simulation experiments. This study fills the gap in vibration analysis of RFSW and provides new insights into control strategies and process optimization for robotic friction stir welding.

Enhancing Friction Stir Welding: Quality Machine Learning Based Friction Stir Welding Tool Condition Monitoring

Ensuring the quality and optimizing the tool in Friction Stir Welding (FSW) process is quite complex and the solution relies on implementing Condition Monitoring. The major impact of this process yields good quality welds and cuts down the non-operational timing and cost. Condition Monitoring is the key to find a solution to the challenging problem of ensuring quality and optimizing the tool in the FSW process. The creation of a graphical user interface (GUI) and the development and comparison of several models, including Decision Tree (DT), Random Forest (RF), Light Gradient Boosted Machine (LGBM), and Extreme Gradient Boosting (XGBoost), are the main objectives of this study. By offering an uniform interface for tracking and evaluating tool condition data, GUI can make it easier for operators and the maintenance crew to collaborate. Vibration analysis is the first step in tool condition monitoring. Al5083 and AZ31B are used as the workpiece and H13 as the tool in this investigation. The signals are obtained from the experimental setup via DAQ, and LabView processes them. A Python script converts the raw signals into statistical data. Following that, the data was loaded into ML models and optimized using Optuna. TKinter has been used to create the GUI. For prediction, the best models were included in the GUI. By the deployed models, LGBM generates 96% for 1000 rpm, 96.55% for 1200 rpm, and 95.90% for 1400 rpm for Al5083 93.22% for 1000 rpm, 99.29% for 1200 rpm, and 91.50% for 1000 rpm for AZ31B. For real-time prediction, these models are thus connected to a graphical user interface. In each case, the LGBM classifier topped the others. This work served as an initial basis for the creation of a semi-onboard diagnostic approach that requires minimal human input.

The Effect of Friction Stir Weld (FSW) Process Parameters on Tensile Strength, Macro Structure, and Hardness in Results of AA7075 Butt Joints

Friction Stir Welding (FSW) is an innovative technique that enhances the conventional method of joining metals. Notably ecofriendly due to its energy efficiency, FSW involves minimal energy input, reduces pollution, and saves time and costs. It finds applications in diverse sectors such as automotive, aerospace, and industry. Each material requires specific process parameters, which leads to this study focusing on identifying suitable parameters for AA7075 aluminum with a 6mm thickness. Using a tool featuring a tapered cylindrical thread pin and a flat shoulder, the study aims to investigate the influence of FSW process parameters, rotation speed, and traverse speed on the mechanical strength of butt joint connections. The study's experimental design varies these parameters and evaluates the joints through tensile strength testing, hardness testing, and macrostructural analysis. Utilizing Response Surface Methodology (RSM), the data highlights the impact of rotation and traverse speed on tensile strength. Hardness test results present variations within heat zones, analyzing the effects of the mentioned variables. The findings demonstrate minimal flash and successful surface outcomes but also identify wormholes within the stir zone (SZ). Tensile strength testing reveals a definite correlation between RPM and traverse speed with joint strength. In contrast, hardness testing indicates that these parameters do not significantly affect joint hardness. Macrostructure examination suggests RPM and traverse speed have negligible effects on the heat-affected zone. In conclusion, FSW presents a sustainable and effective welding approach with implications for multiple industries, and this research provides insights into optimizing its parameters for specific aluminum materials.

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.

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

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.

Optimization of Process Parameters in Under Water Friction Stir Welded AA2014 and AA6082 joints.

This work focuses on optimizing process parameters in underwater friction stir welding to study their impact on the mechanical characteristics of aluminum 2014 T6 and 6082 T6 joints. The aluminum plates are precisely machined to provide the necessary polish for the underwater friction stir welding process (UFSW). Experiments are designed using Taguchi L-9 orthogonal array, considering three process parameters: speed, transverse speed, and tool angles at three levels each. The aluminum plates of series 2014-T6 and 6082-T6 are securely installed in the machine. The plates will be welded using the UFSW process using a taper pin tool. The welded plates are next subjected to tests to assess their mechanical qualities. Tests for tensile strength, hardness, and impact strength are conducted on the welded area of the plate to determine its mechanical qualities. An ANOVA was conducted to determine the significant influence of each variable. The optimal values achieved are Tensile Strength of 185.592 N/mm2, Hardness of 75.1 (BHN), and Impact Strength of 21.236 Joules at a speed of 1120 rpm, transverse speed of 80 mm/min, and tilt angle of 2 degrees.