Friction Stir Welding Of Alloy Research Articles

Comparative numerical analysis between butt and lap joints of Mg alloy friction stir welding with considering tilted tool effect

Magnesium (Mg) alloy, as an important lightweight structural metal, can be effectively joined by the friction stir welding (FSW) method. Understanding FSW temperature and material flow coupling process in butt and lap welding configurations has important theoretical significance. In this study, the tilted tool induced incomplete contact distance is calculated by process parameters and slip rate, and the deflection of the contact interface is related to the tool torque. The non-uniform boundary conditions are considered. The numerical model is proposed and experimentally validated by using the measured temperatures and thermo-mechanically affected zone (TMAZ) profiles. The comparative numerical analysis between butt and lap welding with three levels of process parameters is further conducted. The peak temperature and material flow velocity along the specified circumferences in FSBW are more than 10 K and 4 mm/s higher than these in FSLW, respectively. When the rotation rate increases from 600 rpm to 800 rpm, the peak temperature and material flow velocity along the specified circumferences increase about 20 K and 9 mm/s, respectively. When the welding speed decreases from 150 mm/min to 30 mm/min, the temperature and material flow velocity fluctuations along the specified circumference decreases about 25 K and 14 mm/s, respectively.

Parametric Optimization of Friction Stir Welding of AA6061-T6 Samples Using the Copper Donor Stir-Assisted Material Method

This study presents an optimization of the process parameters for the effect of copper (Cu) donor material percentage on the friction stir welding (FSW) of AA6061-T6 alloy. Extensive factorial experiments were conducted to determine the significance of the rotational speed (ω), the transverse speed (v), the interface coefficient of friction (μ), and the Cu donor material percentage in the plunge, left, right, and downstream zones. Design Expert 13 software was used to identify the number of simulation experiments to be conducted using the Abaqus simulation software. From Design Expert 13, which is a thorough multi-objective optimization analysis software, we were able to identify ideal welding parameters such as a rotational speed of 1222 rpm, transverse speed of 1.1 mm/s, the coefficient of friction of 0.9, and a 19% donor material percentage for the plunge zone. Significant findings demonstrate that increasing the Cu donor material substantially reduced the temperature from 502 °C to 134 °C when the Cu content is increased from 0% to 50%. This integrated modeling and optimization approach provides a practical procedure to identify the best experimental parameters for the process and a new understanding to guide advances for high-quality FSW of aluminum alloys. This work offers a methodology for optimizing the FSW parameters aligned with multifaceted thermomechanical physics.

A Study of Process Parameters for the Friction Stir Welding of Dissimilar Aluminum Alloy by Taguchi Method

A Study of Process Parameters for the Friction Stir Welding of Dissimilar Aluminum Alloy by Taguchi Method

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.

Revealing the microstructure characteristics, deformation behavior and mechanical properties of weakly textured Mg–Y-Nd-Gd-Zr alloy FSW joints

In this work, friction stir welding (FSW) was performed on Mg–Y-Nd-Gd-Zr plate using two different welding parameters: 100 mm/min-1600 rpm and 100 mm/min-1000 rpm. The mechanical properties, deformation characteristic and microstructure of the FSW joints were thoroughly explored. Microstructure analysis revealed a significant refinement in the nugget zone (NZ), with original precipitates being considerably remelted into the matrix. Moreover, the micro-texture in NZ showed symmetrical distribution features, with the highest texture intensity at the NZ-side of the advancing side. Tensile results displayed that the strength of both joints exceeded 95% of the base material (BM), while their elongation was markedly inferior to the BM, with values of 13.8% and 12.2%, respectively. The higher joint connection strength was attributed to the combined effects of dislocation strengthening, grain refinement, precipitation phase re-dissolution softening, and favorable orientation of basal slip near the weld interface.

Improving joint performance of friction stir welded 2195-O Al–Li alloy by post-weld heat treatment and rolling deformation

Post-weld heat treatment and rolling deformation are used to improve the mechanical properties of 2195-O Al–Li alloy friction stir welding (FSW) joints, and the effects on the grain structure, precipitation behaviors, hardness distribution, and tensile performance are discussed. Microstructural characterization was conducted using scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM). Mechanical properties were measured by hardness test and tensile test. Results show that coarse precipitates are subjected to various degrees of dissolution after FSW. Solution treatment following artificial aging (SAA) and 40% rolling deformation + SAA treatment (R40-SAA) enables the dissolution of coarse precipitates completely and precipitation of strengthening phases (T1 and θ′) in the nugget zone (NZ), thermo-mechanically affected zone and heat-affected zone (HAZ). These strengthening precipitates have little difference in precipitation behavior after SAA and R40-SAA treatment and remain consistent across all regions, resulting in joint hardness change a little between these two joints with a homogeneous distribution. The change in precipitates leads to an increase in hardness and enhances both the SAA joint strength and the R40-SAA joint strength to 503 MPa and 528 MPa (superior to the original joints by 309 MPa and 334 MPa, respectively), respectively. The SAA joints fracture in the NZ resulting from the development of AGG, and develop an intergranular fracture morphology with an elongation of 4.2%. The R40-SAA joints have an elongation of 7.2% due to the generation of uniformly fine grains in the NZ, and fail in the HAZ exhibiting a brittle fracture mechanism.

Microstructure, microhardness and mechanical behavior of dissimilar AA7075/AA6061 alloys under friction stir welding

Friction stir welding (FSW) of dissimilar AA6061 and AA7075 aluminum alloys faces challenges such as an unclear forming mechanism and low welding efficiency. In order to improve welding efficiency and elucidate the variations in metallography, Microhardness, and mechanical properties of dissimilar alloy FSW joints, this article designed FSW experiments using the Taguchi method with welding speeds ranging from 600 to 1000 mm/min. We studied the relationship between material mixing and welding defects through macroscopic metallography, microscopic metallography, and Microhardness, while the impact of welding parameters on the microstructure and properties was evaluated. The results show that void defects do not exist in dissimilar alloy FSW joints, and the Microhardness changes are “U” and “W” shaped. Material mixing played a decisive role in determining the microstructure and properties of dissimilar aluminum alloy FSW joints, with increased rotational speed enhancing material flow. The order of influence on the mechanical properties of the joint was found to be plunge depth, welding speed, and rotational speed. Under the conditions of 1000 mm/min, 2400 rpm, and 0.25 mm, the yield strength (YS) and ultimate tensile strength (UTS) of the dissimilar alloy FSW joints reached 87.3% and 73.4% of the AA6061-T6 alloy, respectively.

Effect of base material temper condition on precipitate evolution and mechanical properties of 2195 Al[sbnd]Li alloy friction stir welding joints

In this study, 2195 AlLi alloy plates with different temper conditions (O, T4 and T8) were subjected to friction stir welding (FSW). Precipitate evolution of the three FSW joints (2195-O/T4/T8 joint) was investigated by transmission electron microscopy (TEM). Mechanical properties of these joints were analyzed using micro-hardness and tensile test. Efforts were made to explore the correlation between precipitates, mechanical properties and fracture behavior of the joints. It can be found that the precipitates from the base material are unevenly dissolved in the nugget zone (NZ) of the 2195-O joint, while the original precipitates mostly disappear in NZ of the 2195-T8 joint, and change a little in the NZ of the 2195-T4 joint. In the thermal-mechanically affected zone (TMAZ) of the 2195-O and 2195-T4 joint, precipitates are almost unchanged, while in the TMAZ of the 2195-T8 joint, most of the precipitates are dissolved and the residual is significantly coarsened. Little change of precipitates occurs in the heat affected zone (HAZ) of the 2195-O joint. T1 newly forms in the HAZ of the 2195-T4 joint (T4-HAZ), while this precipitate is mainly dissolved and coarsened in the HAZ of the 2195-T8 joint (T8-HAZ). Moreover, both grain boundary phases (GBPs) and precipitate-free zone (PFZ) are generated in the T4-HAZ and T8-HAZ. Hardness profile is represented as a “n” shape in the 2195-O joint due to significant harden of the NZ, a “wave line” shape in the 2195-T4 joint attributed to the slight change of precipitation degree, and a “w” shape in the 2195-T8 joint mainly owing to the dissolution and coarsening of T1. The three joints are all broken in their weak regions during tensile test and have a similar fracture behavior, indicating that the crack initiation and development are related to the GBPs and PFZ.

Numerical analysis of thermal differential distribution in Bobbin tool friction stir welding of 7075-AZ31B dissimilar alloy

The theoretical model of bobbin tool friction stir welding (BT-FSW) structure and dynamic process is established. Because of the great differences in properties of different materials, the mathematical relationship between material stress and deformation will be expressed based on 3D transient heat conduction equation and J-C constitutive model. The BT-FSW process of 7075 and AZ31B was analyzed by finite element method, and the field distribution, thermal cycle curve and stress distribution characteristics of different welding areas of the welded material were simulated. To predict and control the non-equilibrium distribution of welding temperature and stress field, the influences of different Rotating speed, welding speed, offset and other variables on the BT-FSW process of 7075/AZ31B aluminum magnesium dissimilar alloy were studied comprehensively. Finally, the reliability of the model is proved by fitting the experimental and numerical analysis results. The research results show that the temperature of BT-FSW presents an “hourglass” symmetrical distribution, and the stress distribution on both sides of the plate is uniform when the aluminum alloy is placed on the advancing side, the stirring tool is offset to the aluminum alloy by 2mm, and the rotating speed and welding speed are 700r/min and 180mm/min, respectively.

Optimizing and Redesigning the Vertical Milling Fixture for Friction Stir Welding of Aluminium Alloy (Al 6061)

Friction stir welding is a kind of solid-state fusion process for welding like or unlike metals. Established and patented by “The Institute of Welding” in the UK in December 1991, it involves using a compressive force applied by a conventional milling machine to make contact with work-pieces. The work-pieces are one or the other revolving or moving proportional to a pin tool, generating the heat necessary for atomic diffusion and thereby uniting the material at the edges. FSW can be functional in a variety of materials, together with stainless steel, aluminium, and various alloys. The process typically takes place on vertical milling machines, requiring a vertical milling fixture to firmly hold the plates being welded. In this paper, vertical milling holding setup and fixture for FSW procedures on vertical milling machines are established. Materials such as aluminium and aluminium alloy (Al 6061) are analyzed for their suitability in FSW operations, to identify the best material for the process. Additionally, there is potential for extending the FSW process to plastics and similar materials. Friction stir welding offers significant advantages in terms of weld quality, strength, and versatility across a range of industries, making it a versatile option for solid-state joining processes.

Corrosion and protection of friction stir welding of magnesium alloy

Purpose The high specific strength makes magnesium alloys have a wide range of applications in aerospace, military, automotive, marine and construction industries. However, its poor corrosion resistance and weldability have limited its development and application. Friction stir welding (FSW) can effectively avoid the defects of fusion welding. However, the microstructure, mechanical properties and corrosion behavior of FSW joints in magnesium alloys vary among different regions. The purpose of this paper is to review the corrosion of magnesium alloy FSW joints, and to summarize the protection technology of welded joints. Design/methodology/approach The corrosion of magnesium alloy FSW joints includes electrochemical corrosion and stress corrosion. This paper summarizes corrosion protection techniques for magnesium alloys FSW joints, focusing on composition, microstructure changes and surface treatment methods. Findings Currently, this research is mainly focused on enhancing the corrosion resistance of magnesium alloy FSW joints by changing compositions, structural modifications and surface coating technologies. Refinement of the grains can be achieved by adjusting welding process parameters, which in turn minimizes the effects of the second phase on the alloy’s corrosion resistance. Originality/value This paper presents a comprehensive review on the corrosion and protection of magnesium alloys FSW joints, covering the latest research advancements and practical applications. It aims to equip researchers with a better insight into the field and inspire new studies on this topic.

Performance Assessment of Different Pin Profiles in Friction Stir Welding of AA2014 Aluminum Alloy: A Microstructural and Mechanical Analysis

Performance Assessment of Different Pin Profiles in Friction Stir Welding of AA2014 Aluminum Alloy: A Microstructural and Mechanical Analysis

A Comparative Study of Conventional, Dynamic Rotation and Heat-assisted Friction Stir Welding of Ti-6Al-4V Plates to Reduce Welding Defects

It is very easy to form bottom defects during friction stir welding (FSW) of medium-thick/thick Ti alloys, while there is a lack of in-depth research on its essential cause. In this study, conventional FSW (CFSW), dynamic rotation FSW (DRFSW) and back heating assisted FSW (BHAFSW) were conducted to 6mm Ti-6Al-4V plates. The combination of experimental examination and finite element modelling was utilized to deeply study the bottom defect formation mechanism. The results showed that bottom defects always existed in both CFSW and DRFSW joints, which was mainly attributed to the phase transformation difference at the joint bottom, as the result of the difference of the bottom temperature and the phase transformation point. A proper bottom temperature compensation of 150oC via BHAFSW was designed to avoid the phase transition difference and improve the material flow, which effectively eliminated the bottom defects. This is the first time to uncover the reason of the bottom defect generation during FSW, and thus defect-free Ti alloy medium-thick plate joints were achieved via BHAFSW. The BHAFSW joint achieved the 1022MPa in strength and 16% in ductility, with the equal strength to the base material (BM) but with very few losses of the ductility. The joint exhibited an impact toughness of 10.4J, 48.1% higher than the BM. This study uncovers the reason for the typical bottom defect and provides a new way to improve the quality of medium-thick/thick Ti alloy FSW joints.

Study on the Properties of a 2219 Aluminum Alloy Friction Stir-Welded Joint under the Biaxial Stress State

Friction stir welding (FSW) has been considered ideal for aluminum alloy structures. The performance of FSW joints under unidirectional stress state has been widely tested, but there is still a lack of experimental data under a biaxial stress state. For accurate characterization of the mechanical properties of 2219 aluminum alloy FSW joints under a biaxial stress state, this article conducted biaxial tests. The FSW joint was tested using scanning electron microscopy (SEM) to obtain its microscopic properties and obtain the partition results of the welded joint. The stress–strain relationship and yield characteristics of welded joints under different loading ratios were studied using biaxial tensile tests of cruciform specimens combined with digital image correlation technology. By comparing it with the existing yield criteria, the yield criterion suitable for FSW joints of 2219 aluminum alloy under a biaxial tensile load was determined.

The effect of friction stir welding on the microstructure and mechanical properties of the dissimilar SS304 and Al7075-T6 alloy joints

This study focuses on the friction stir welding (FSW) of dissimilar materials, Al7075 alloy and SS304 stainless steel, in a butt configuration. The objective is to examine the impact of different operating conditions, including tool rotational speed, transverse speed, and tool offset, on the FSW process of the dissimilar sheets. Mechanical properties, specifically the ultimate tensile strength, were found to be influenced by rotational speed. Higher rotational speed resulted in decreased tensile strength due to increased heat generation in the weld zone, leading to the formation of a thicker intermetallic layer. Higher tool rotational speed and greater transverse feed rate improved weld joint performance. Microstructural changes and deformation properties were investigated using optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The FSW process caused significant grain refinement, creating a fine and equiaxed recrystallized grain structure. Intermetallic compounds like Al13Fe14, Al3Fe2, and Al3Mg2 were identified in the interface zone. In summary, this study provides valuable insights into the FSW of dissimilar materials. It sheds light on mechanical properties, microstructural changes, and intermetallic compound formation in the welded joint, contributing to the understanding of FSW for dissimilar materials.

Improvement of weldability and fracture behavior of mild steel and A7075 aluminum alloy dissimilar friction stir welded joints by increasing welding speed

In this study, dissimilar friction stir welding of mild steel and A7075 aluminum alloy was conducted at a constant tool rotational speed (900 rpm) and different welding speeds of 100–400 mm/min with an interval of 100 mm/min. A thermocouple was employed to record the thermal cycle and the maximum reached temperatures of the A7075/steel interface during the joining process. The higher the welding speed, the lower the maximum temperature recorded during the joining process. Conducting the joining process at a high welding speed also enhanced the cooling rate and, thus, effectively contributed towards eliminating the thermal residual stresses and suppressing the interfacial intermetallic compounds growth. As a result, 100% joint efficiency with a steel base metal fracture was obtained for the joints fabricated at the welding speeds of 300 and 400 mm/min.

Phase-field simulation of dynamic recrystallization in friction stir weld nugget zone of dissimilar Al/Mg alloys

In friction stir welding (FSW) of dissimilar Al/Mg alloys, the materials on both sides in weld nugget zone (WNZ) undergo extremely uneven high temperature and plastic deformation, resulting in a great difference in dynamic recrystallization (DRX) which determines the weld microstructure evolution. In this study, the multi-phase field model coupled with the dislocation density model is developed to conduct numerical simulation of DRX behavior in WNZ of Al/Mg alloys FSW with Mg placed on advancing side. It is found that during welding process, the grain size at the checking points in WNZ always decreases rapidly at first and then increases slowly to a stable value, while the dislocation density always increases first and then decreases to a stable level. After welding, the final grain size on Al's side is lower than that on Mg's side. As the welding speed decreases, the DRX becomes more intense, and the dislocation density curve fluctuates more frequently. The calculated final values of average grain size at both Al's and Mg's sides are in good agreement with the experimentally measured ones.

Significance of FSW process parameters and tialite particle reinforcement at the weld zone of AA6082 alloy

In the current work, tialite (Al2TiO5) ceramic particles are added at the weldment during the friction stir welding of AA6082-T6 aluminium alloy. Three different values of tool rotational speed (TRS) (1000, 1200 and 1400 rpm) and welding speed (WS) (35, 40 and 45 mm/min) are taken into consideration in fabricating joints. Totally nine joints are fabricated by adding tialite particles and examinations like microstructural analysis and mechanical properties are carried out to find the quality of the joints. Defect-free welds are obtained for optimal process parameters which is a result of good mixing of base materials with uniform particle distribution. The highest ultimate tensile strength (UTS) (273 MPa) is noticed for specimen fabricated using TRS 1200 rpm and WS 40 mm/min. The peaks from the X-Ray diffraction (XRD) analysis have confirmed the presence of tialite particles in the welded samples. According to the micro hardness profile, the stir zone (SZ) (136.4 HV) and heat affected zone (HAZ) (79.8 HV) have the highest and lowest micro hardness values, respectively.

Prediction of Axial Force on Dissimilar Aluminum Alloys Friction Stir Welding Using Design of Experiment

Friction stir welding (FSW) has become very popular for joining similar or dissimilar aluminum alloys. The heat used for this welding process is caused by friction between the welding tool and the workpiece which the axial force, the main parameter for heat generation, plays a very important role. Insufficient heat during welding will result in defective workpieces. This research is aimed to predict the axial force from the relevant factors of the FSW of dissimilar materials (aluminum alloys AA2024-T3 and AA6061-T6). The 23 full factorial design with center point was used for this experiment that consisted of 3 main factors: 1) rotation speed (rpm), 2) welding speed (mm/min), and 3) pin geometry each factor has 2 levels and 2 replications with the total of 20 experiments. The axial force data of each experiment were collected using a stationary dynamometer which obtained the data acquisition every 0.1 seconds (frequency of 10 Hz). The results from the design of experiment were analyzed by statistical method at the significance level of α = 0.05 which found that the significance and the optimum value of the main factors were rotation speed of 1500 rpm, welding speed of 35 mm/min, pin geometry of tri flat threaded, and the 2-way interaction between rotation speed and pin geometry. Furthermore, the prediction of the average axial force value on dissimilar aluminum alloys obtained from the specified parameters equals 478.91 N.

Multi-objective optimization of process parameters during friction stir welding of similar AA6061 using MOORA

This work is an attempt to select the optimum process parameters for friction stir welding of similar AA6061 aluminum alloy based on multiple criteria decision-making approach. The friction stir welding experiments have been conducted according to the orthogonal L9 array and the chosen input parameters are tool rotational speed, feed, and tilt angle. The responses measured are tensile strength, hardness, and % of elongation of welded joint. The multi-criteria decision-making technique namely multi-objective optimization based on the ratio analysis (MOORA) is used to find the optimum process parameters combination. The optimum conditions are tool rotational speed of 1120 rpm, feed of 30 mm/rev and tilt angle at 1 o.