Taguchi–PSI based optimization of formability parameters in dissimilar friction stir welded A390–AA2214 aluminum alloy joints

Attractive properties of aluminum alloys make them popular in numerous engineering applications. But some issues are reported in traditional welding processes. An effective method of Friction Stir Welding (FSW) is suggested for joining aluminum alloys. However, the effect of temperature, the strain rate and specimen orientation on the formability of dissimilar welded alloys is not well understood. The dissimilar AA390 and AA2214 were welded by FSW at a rotational speed of 1120 rpm and a traverse speed of 50 mm/min with no tool tilting in this study. The mechanical performance was assessed by performing uniaxial tensile tests under different temperatures, strain rates, and angles with respect to the rolling direction. A Taguchi analysis and Preference Selection Index (PSI) method were used to determine the optimum formability conditions. The results demonstrated that testing temperature was the dominant factor affecting the tensile behaviour of the dissimilar FSW joint. Increasing the temperature decreased the ultimate tensile strength and yield strength but increased percentage elongation, indicating a transition toward greater ductility at elevated temperatures. The PSI main-effects analysis predicted the optimal combined-response condition at a rolling-direction orientation of 60°, a temperature of 120 °C, and a strain rate of 0.0006 s−1.