Microstructure and mechanical properties of aluminum alloy and galvanized steel joints by fiber laser fusion welding-brazing using a rectangular spot with filler powder

Fluxless fiber laser fusion welding-brazing with rectangular spot was used to produce joints between 6061-T6 aluminum alloy and galvanized steel with filler powder. The joints were evaluated by metallurgical analysis and mechanical properties testing. The results indicated that favorable joint with good figuration,no crack and pore were present with optimized welding parameters. Furthermore,the joint was characterized by layered and dendritic microstructure. The layered structure is composed of Fe₂Al₅. The dendritic part is identified as τ1 and Fe₄Al₁₃ phases. In addition,failures were observed in the weld/steel interface with brittle characteristics from the tensile test. The mechanical resistance of the joint is determined by the ratio of width of weld interface and the maximum thickness of intermetallic compounds layer.