Magnetic pulse joining of aluminum alloy-carbon steel tubes

The magnetic pulse joining (MPJ) between 3A21 aluminum alloy and steel 20 tubes was experimentally investigated with a solenoid coil assisted by a field shaper. The mechanical properties and microstructure of MPJ joints were tested and observed. The results show that the metallurgical joints can be obtained at a voltage of 15 kV, a radial gap of 1.2-1.4 mm, and a slope angle of 3°-7°in the lapping area. The joint comprises a transition zone with different widths, two matrix metals and two interfaces between the zone and the two metals. The interface presents a typical wavy pattern and mutual diffusion of Fe and Al elements happens in the zone. The transition zone is composed of Fe-Al intermetallics, micro cracks and micro pores. The microhardness of the transition zone is much higher than that of the matrix metals.