Interfacial microstructure of stainless steel/aluminum alloy tube lap joints fabricated via magnetic pulse welding

Magnetic pulse welding was utilized to join 5A02 aluminum alloy and SS304 stainless steel tubes under a discharge voltage of 15-17 kV and 1.75 mm radial gap. SEM, TEM, and EDS analyses are performed to assess the interface microstructure of the transition zone joint. The interface with the transition zone is composed of an amorphous matrix comprised mostly of Al with relatively less Fe, plus irregular nanocrystalline second phases embedded within the amorphous phase matrix. The magnetic pulse welding interface with the transition zone essentially forms a fused interface and the base metals on both sides of the transition zone maintain the deformed structure exhibiting severe plastic deformation, grain refinement, and an increased hardness near the interface.