Mechanical properties and joining mechanisms of Al-Fe magnetic pulse welding by spot form for automotive application

Magnetic pulse welding (MPW) has the unique advantages in realizing the connection of dissimilar materials, such as waveform interface, reliable joint and high strength. However, the air gap must be ensured by placing the gasket. Magnetic pulse spot welding (MPSW) has great potential in industrial applications for not requiring additional equipment to ensure the air gap between the two plates during the welding process. In this paper, a comparative study of flat-head type welding joint and convex-head type welding joint with dissimilar materials jointed by MPSW was carried out. Mechanical properties, joining mechanism, and interfacial morphology of the two joints were studied by tensile tests, numerical simulations, and microscopic observations. The results showed that different forms of flyer plate had a significant influence on the performance of the joint as it led to different weld lengths. The tensile strength of the convex-head type was higher than that of the flat-head type. In contrast, the flat-head type had better shear strength than the convex-head type because additional torsional force was formed. In general, these two different joints of MPSW had their characteristics. Therefore, the type of welding joint could be selected according to the actual needs. This research broadens the idea of the MPSW of Al-Fe for vehicle bodies applications.