The dissimilar materials, aluminum alloys and galvanized steels were joined by CMT welding-brazing method. Analyzing the macro feature of cross-section, microstructure, the defects and mechanical properties of welding-brazing joints with SEM, EDAX, tension text, it is shown that the lap joints with better properties and better weld appearance are formed between the aluminum alloys and galvanized steels. From the microstructure and formation of weld metal, the cross-section of the joint can be divided into four zones: weld metal, middle interface, transitional interface and zinc-rich zone. There is a continuous and compact inter-metallic compound layers with a thickness of 3~4μm, which is formed in the brazing interface zone between the weld metal and the galvanized steel sheet. The main components of the layer are Fe3Al,FeAl2,Fe2Al5 and FeAl3,then, the zinc-rich zone is mainly composed of aluminum-rich solid solution and residue of Zn. Tensile strength tests show that the joint is fractured in the aluminum heat affect zone, and the joint strength with 204MPa is obtained.
