Analysis on microstructure and mechanical properties of aluminum alloy/stainless steel joint made with flux-cored filler metal

Dissimilar metal joining between 5A02 aluminum alloy and AISI 304 stainless steel was conducted by gas tungsten arc welding with ZnAl15 and AlSi12 flux-cored filler metals, and the effect of the filler metal composition on the microstructures and mechanical properties of the joints were investigated. The results revealed that the tensile strength of as-welded joints made with ZnAl15 and AlSi12 flux-cored filler metals was 121 MPa and 162 MPa respectively. After annealed at 280℃ for 30 min, the tensile strength of joints made with ZnAl15 fluxcored filler metal reached 180 MPa, while that with AlSi12 fluxcored filler metal was 166 MPa. The interfacial layer in the weld made with ZnAl15 filler metal was comprised ofFeAl₃Zn_x andFe₂Al₅Zn_x, and ternary intermetallic compound Al_7.4Fe₂Si was found in the interfacial layer in the joint made with AlSi12 flux-cored filler metal. The thickness of the interfacial layers made with both filler metal was less than 10μm.