Research on Effect of Cu on Microstructure of Interface Area of Aluminum/Steel CMT Welding-brazing Joint

The cold metal transfer method was used for lap fusion welding with AlSi5 welding wire as the filler metal and Cu foil added between 5052 aluminum alloy and galvanized steel plate. The interfacial microstructure and properties of the joint were studied by scanning electron microscope combined with energy spectrum analysis and tensile test machine. The results show that without copper foil addition, the microstructure of the interfacial zone is mainly composed of FeAl₃ intermetallic compounds.The addition of copper foil makes the interfacial area generate CuAl₂ intermetallic compounds, and improves the distribution of Zn in the interface area. Zn solid dissolves into Al, which inhibits the formation of Fe-Al intermetallic compounds.The fracture position changes after adding Cu foil, and the strength is similar to that without Cu foil.