Basic Study on Process Parameter Control to Induce Button Fracture in SPREW(Self Piercing Resistance Element Welding) of 2.4 mm Al6451 and 1.0 mm GA-980

Self Piercing Resistance Element Welding (SPREW) is a dissimilar welding process based on resistance spot welding, using a steel rivet. This method employs a steel rivet to pierce the aluminum sheet under a piercing current, then a welding current is conducted to weld the rivet to the steel sheet. Previous studies have focused on relatively thin aluminum sheets (≤1.5 mm), and research on thicker aluminum sheets has rarely been attempted. In this study, the SPREW process was applied to join a 2.4 mm-thick aluminum alloy (Al6451) and a 1.0 mm-thick galvanized high-strength steel (GA-980). By varying the piercing current, piercing time, cooling time, welding current, and welding force, tensile load and fracture mode were evaluated. The best joint performance-a maximum tensile load of 6.38 kN with button fracture-was achieved at 2 kA, 6 s, 10 s, 10 kA, and 4.4 kN, respectively.