Investigation of Collision Surfaces and Weld Interface in Magnetic Pulse Welding of Dissimilar Al/Cu Sheets

Magnetic Pulse Welding (MPW) is an essential procedure for joining of dissimilar metals. The high velocity collision and jetting are the most important aspects of MPW controlled by welding parameters: discharge voltage and air gap. In this study, the collision surfaces and interface of MPW of pure Al and Cu are investigated. The effect of air gap on the bonding is studied by variation of the air gap from 0.7 to 4 mm. The collision surfaces of Cu and Al, the interface of welding and fracture surface were examined by optical microscope and SEM equipped with EDS analysis. The results revealed that the metallurgical bonding is obtained in the air gap of 0.7 mm, whereas higher air gaps (1 to 4 mm) result in debonding due to higher impact energy. The feature of collision surfaces depends on the physical properties of Al and Cu, the variation of collision angle and distance from the centerline of the collision. By increasing the collision angle and distance from the centerline of the collision, the porous and wavy structures in the collision surface of Al, and wavy structure with vortices in the collision surface of Cu are formed. Furthermore, by increasing the distance from the centerline of collision, the wavy structure with vortices is formed in the interface of welding. Also, the highest shear strength is obtained at the middle of the weld line, and the failure is occurred in Al.