Effects of thickness of zinc layer on microstructure and properties of CMT lap welding joint between aluminum and galvanized steel

It aimed to investigate that effects of the thickness of zinc coating on the microstructure and properties of 6082 aluminum alloy/galvanized steel joint. The thickness of zinc layer was 10, 30 and 60 μm(No.1, No.2, No.3), respectively. The results showed that the No.1 weld shape was poor, with zinc layer ablation of the edge; and the appearance of No.3 weld seam was better and the wettability was better. Tensile properties of No.1 and No.3 welded joint was poor, and the tensile bearing capacity of the No.2 weld seam was 9 519.5 N. The zinc layer mainly affected the zinc-rich zone and the interfacial zone, and the zinc-rich zone had dendrites and cracks. The intermetallic compounds in the interfacial zone were Fe-Al-Zn compound, which formed only in the vicinity of the intermediate position of the interfacial zone. The No.3 compound layer produced was 4 ~ 6 μm, and the No.1 and No.2 compound layer was 1 ~ 2 μm. In summary, a suitable galvanized layer thickness was required to obtain a welded joint with good performance.