Effect of wire feeding positions on microstructure and properties of CMT lap welding joint between aluminum and galvanized steel

Effect of wire feeding positions on the weld joint quality of 6082 aluminum/ galvanized steel was studied by CMT lap welding method. The surface morphology and microstructure were observed by metallographic microscope and SEM, respectively, and element distribution was measured by EDS. The mechanical properties of the weld joint were measured by tensile test. The results show that the shape of weld joints was not plump, when the wire feeding was at 1 and 2 position and the zinc layer of galvanized steel evaporated seriously. The intermetallic compounds of FeAl₂, FeAl and FeAl₃ formed at the interface. The tensile strength of weld joint was 6 kN. The better shape of weld joints was prepared when the wire feeding was pointed to the aluminum plate. Fe_6.6Al₃Zn_0.2 and Fe₂Al₃Si_0.3 were founded at the interface with about 2 μm in thickness. The tensile strength of weld joint was 7.5 kN. In summary, the wire feeding direction should be pointed to aluminum alloy during CMT lap welding for a good performance of weld joints.