Mechanical Properties Of Friction Stir Welding Research Articles

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.

A Comprehensive Review on Optimal Welding Conditions for Friction Stir Welding of Thermoplastic Polymers and Their Composites.

Friction stir welding (FSW) and friction stir spot welding (FSSW) techniques are becoming widely popular joining techniques because of their increasing potential applications in automotive, aerospace, and other structural industries. These techniques have not only successfully joined similar and dissimilar metal and polymer parts but have also successfully developed polymer-metallic hybrid joints. This study classifies the literature available on the FSW and FSSW of thermoplastic polymers and polymer composites on the basis of joining materials (similar or dissimilar), joint configurations, tooling conditions, medium conditions, and study types. It provides a state-of-the-art and detailed review of the experimental studies available on the FSW and FSSW between similar thermoplastics. The mechanical properties of FSW (butt- and lap-joint configurations) and FSSW weld joints depend on various factors. These factors include the welding process parameters (tool rotational speed, tool traverse speed, tool tilt angle, etc.), base material, tool geometry (pin and shoulder size, pin profile, etc.) and tool material, and medium conditions (submerged, non-submerged, heat-assisted tooling, cooling-assisted tooling). Because of the dependence on many factors, it is difficult to optimize the welding conditions to obtain a high-quality weld joint with superior mechanical properties. The general guidelines are established by reviewing the available literature. These guidelines, if followed, will help to achieve high-quality weld joints with least defects and superior mechanical properties. Apart from parametric-based studies, the statistical-based studies (e.g., analysis of variance (ANOVA)-based studies) are covered, which helps with the determination of the influential parameters that affect the FSW and FSSW weld joint strength. Also, the optimal ranges of the most influential process parameters for different thermoplastic materials are established. The current work on the development of general guidelines and determination of influential parameters and their operating ranges from published literature can help with designing smart future experimental studies for obtaining the global optimum welding conditions. The gaps in the available literature and recommendations for future studies are also discussed.

Physical Model Based on Data-Driven Analysis of Chemical Composition Effects of Friction Stir Welding

Variations in chemical compositions can lead to changes in the mechanical properties during friction stir welding (FSW). To facilitate control over the final mechanical properties of the friction stir weld, the relationship between the chemical compositions and final mechanical properties must be investigated. An artificial neural network was used for a data-driven analysis of the effects that chemical compositions have on the mechanical properties of FSW. A precipitate evolution model was implemented to examine the detailed contributions of different elements to the final mechanical properties. Experiments with different chemical compositions were conducted to validate the established models. Through both numerical and experimental analyses, it was determined that the yield strength in the stir zone increased with an increase in Mg/Si owing to the formation of Mg2Si. The mechanical properties also increased with Si, Mg, and Cu contents in the solid solution. The mechanical properties decreased with an increase in the Fe and Mn contents owing to the formation of an intermetallic compound α-Alx(MnFe)ySiz. The final mechanical properties were determined by both the welding temperature and chemical compositions. By utilizing a physical model based on a data-driven analysis, the mechanical properties could be optimally controlled.

Modeling Mechanical Properties of FSW Thick Pure Copper Plates and Optimizing It Utilizing Artificial Intelligence Techniques

Friction stir welding (FSW) is an innovative solid state joining technique and has been employed in aerospace, rail, automotive and marine industries for joining aluminum, magnesium, zinc and copper alloys. In this process, parameters play a major role in deciding the weld quality these parameters. Using predictive modelling for mechanical properties of FSW not only reduce experiments but also is created standard model for predict outcomes. Therefore, this paper is undertaken to develop a model to predict the microstructure and mechanical properties of FSW. The proposed model is based on Ring Probabilistic logic Neural Network (RPLNN) and optimize it utilizing Genetic Algorithms (GA). The simulation results show that performance of the RPLNN algorithm with utilizing Genetic Algorithm optimizing technique compared to real data is reliable to deal with function approximation problems, and it is capable of achieving a solution in few convergence time steps with powerful and reliable results.

Mg/Al REACTION AND MECHANICAL PROPERTIES OF Al ALLOY/Mg ALLOY FRICTION STIR WELDING JOINTS

Mg alloys are increasingly used in aerospace,aircraft and automotives structures due to the low density and good damping properties,especially,the welding of Mg alloy to Al alloys is of practical importance for widening the application of Mg alloys.Although friction stir welding (FSW) has been used to join Mg and Al alloys,defect free joints are achieved only in the thin plate (less than 4 mm).In this paper,three ways of FSW of 6 mm thick 6061-T651 Al alloy and AZ31 Mg alloy plates,offsetting the pin to the seam between the two plates(M4A4),to the Mg alloy side 2 mm(M6A2) and to the Al alloy side 2 mm(A6M2),were studied.The aim is to examine the effects of the relative position between tool and plate on the microstructure and mechanical properties of FSW Mg/Al alloys joint.SEM and XRD analyses revealed the formations of intermetallics Mg_(17)Al_(12) and voids in the interface between Mg and Al alloy plates in the three FSW samples. The voids are resulted from the melting and subsequent solidification of eutectic.In the M4A4 and M6A2 samples,some Al are stirred into the Mg alloy side during FSW,forming the Mg_(17)Al_(12), whereas in the A6M2 sample,some Mg stirred into the Al alloy side are also transformed to the Mg_(17)Al_(12).Some fine pores are observed around the MgnAl_(12).The hardness of the nugget zone exhibits a slight increase due to the formation of a small amount of Mg_(17)Al_(12).The intermetallics and pores at the jointed interface decrease the strength of the joints significantly.