Mechanical property and microstructure of aluminum alloy-steel tubes joint by magnetic pulse welding

The mechanical properties, microstructure and interface pattern of lapped joint of AA3003-O and steel 20 tubes by magnetic pulse welding (MPW) were investigated. The results show that the tension and torsion strength values are higher than that of the aluminum tube when the discharge voltage of MPW process is not less than 8 kV. The metallurgical joint, which composes of interfaces, non-uniform transition zone and basic metals, are obtained under discharge voltage of 15 kV, the preset oblique angle of 4° and radial gap of 1.2–1.4 mm. High-density dislocations and nanocrystals present in basic metals along the interfaces. The transition zone has the highest micro-hardness of 5.1 GPa. The multi-direction micro-cracks and the micro-apertures characterize the transition zone of MPW joint. The mutual diffusion of Fe and Al elements occurs in the transition zone, where content of Al element is higher than Fe element besides a narrow region close to the interface of steel and zone. The narrower transition zone presents more even distribution of basic elements than the wider one.