Mechanical properties of dissimilar resistance spot welds of aluminum to magnesium with Sn-coated steel interlayer

Dissimilar joining of aluminum (AA5052) to magnesium (AZ31) alloys was investigated in the current study by resistance spot welding. The formation of Al-Mg intermetallic compounds was successfully prevented and strong Al/Mg resistance spot welded joints were achieved by inserting a Sn-coated steel interlayer between the two base metals before welding. The tensile shear strength was as high as 88% of the reported value of the Mg/Mg joints. The failure during mechanical loading occurred inside the Al fusion zone away from the Al/steel interface. It follows that the thin Al-Fe reaction layer formed at the Al/steel interface did not significantly affect the tensile strength of the joints. The significant reduction of voids, due to the high boiling temperature of Sn and also long downslope time, may also contribute to the relatively strong Al/steel interfaces.