Experimental Investigation and Statistical Modeling of Friction Stir Spot Welding Process Parameters for AA6082/AA1050 Dissimilar Joints

This study investigated the influence of friction stir spot welding (FSSW) process parameters, specifically rotational speeds of 500, 700, and 900 rpm and dwell times of 2, 4, and 6 s, on the mechanical and microstructural properties of dissimilar AA6082 and AA1050 aluminum alloy joints. The peak temperature during welding, tensile shear load, and joint hardness were evaluated. Mathematical models were developed to establish relationships between the FSSW parameters and measured responses. Analysis of variance (ANOVA) confirmed the significance of the models and influence of individual parameters. The peak temperature exhibited a linear relationship with both the rotational speed and dwell time, whereas the tensile shear load and hardness followed quadratic relationships. Numerical optimization identified an optimal parameter combination of 500 rpm rotational speed and 3.45 s dwell time for superior mechanical performance of the joints. Fracture surface analysis revealed predominantly ductile failure in the AA1050 base material, a more refined dimple structure in AA6082, and a combination of ductile and mixed-mode failure mechanisms at the weld interface of the FSSWed joint produced at 500 rpm and 4 s. These findings provide valuable insights into the optimization of FSSW process parameters for dissimilar aluminum alloy joints.