Process Parameters Optimization of Refill Friction Stir Spot Welded Al/Cu Joint by Response Surface Method

Refill friction stir spot welding is a new branch of friction stir welding. In this study, the dissimilar Al/Cu joint was acquired by refill friction stir spot welding. A quadratic regression model was established by Box–Behnken design to explore the relationships between the key process parameters of rotational velocity, plunge depth and welding time and the joint tensile shear load. The results show that the rotational velocity is the most dominant factor for tensile shear load, while the welding time and plunge depth are the second and third effective process parameters. The contour map and response surface present that tensile shear load first increases and then decreases with the increase of the investigated process parameters. The maximum tensile shear load of 4.69 kN is acquired at the optimized rotational velocity of 2500 rpm, plunge depth of 1.7 mm and welding time of 6.2 s.