Interfacial characterization of joint between mild steel and aluminum alloy welded by resistance spot welding

The interfacial characteristics of resistance spot welded steel–aluminum alloy joint have been investigated using electron microscopy. The results reveal that reaction product FeAl3 is generated in the peripheral region of the weld while a reaction layer consisting of Fe2Al5 adjacent to steel and FeAl3 adjacent to aluminum alloy forms in the central region of the weld, and that the morphology and thickness of the reaction layer vary with the position at the welding interface.