Experimental research on magnetic pulse joining of 3A21 aluminum alloy-20 steel tubes

Magnetic pulse joining (MPJ) is a solid state joining technology, by which mechanical or metallurgical joint is obtained. It can be used to assemble and join dissimilar metals. In this work, by means of MPJ setup with low inductance coil, the effects of discharge voltage, radial gap between tubes and lap length on the tensile and peel testing strength of 3A21 aluminum alloy-20 steel tubes joint were investigated experimentally. The microstructural observation and the energy spectrum analysis (by linear scan) of basic elements distribution within the MPJ joint interface were performed by SEM. The results showed that an increasing discharge voltage contributed to the change of MPJ joint from mechanical joint to metallurgical one. The metallurgical joint with the small wave joining interface was obtained under a voltage of 5.5 kV, a radial gap of 1.5 mm, and a lap length of 3/4 coil length, where the mutual diffusion of Al and Fe elements occurred. The severe plastic deformation with sharp strain gradient, and the distinct grain refinement occurred in the matrix metals near the joining interface.