Interface microstructure and weld strength of steel/aluminum alloy joints by resistance spot welding

摘要

In this study, in order to investigate effects of welding conditions and alloy element Cu in aluminum alloy on growth of intermetallic compounds at weld interfacial zones and weld strength of steel/aluminum alloy joints, the pure aluminum A1050 and the aluminum alloy A2017 to cold-rolling steel SPCC were welded by resistance spot welding. Two intermetallic layers were observed, and the major phases are Fe_2Al_5 adhering to the steel and FeAl_3 adhering to the aluminum. The results of EPMA suggested that diffusion of alloy element Cu in the A2017 happened at the interface, which may be the reason for that the anisotropic growth of Fe_2Al_5 might be inhibited. The tensile-shear strength of A2017/SPCC joint decreased with an increasing of the thickness of r=0.5, considering the nugget radius as 1.