Interfacial microstructure and mechanical properties of Al/Mg butt joints made by MIG welding process with Zn-Cd alloy as interlayer

Abstract

Butt joints between Mg alloy AZ31B and pure Al 1 060 sheets were produced via metal inert gas welding process with Zn-Cd alloy foil. Crack-free Al/Mg butt joints between AZ31B Mg alloy and pure Al 1060 sheets were obtained. Intermetallic compound layer 1 and layer 2 had formed in fusion zone/Mg alloy and the average thickness of the layer 1 was about 50 μm. The intermetallic compound layer 1 consisted of Al₁₂Mg₁₇ and Mg₂Si phases while layer 2 consisted of Al₁₂Mg₁₇, Mg₂Si and MgZn₂ phases. The crack started from the IMC layer at the bottom of the joint and propagated along the brittle IMC layer, then expanded into weld metal during the SEM in situ tensile test. The highest tensile strength of the dissimilar metal butt joints could reach 46.8 MPa and the effect of interfacial IMC layer on mechanical property of the joint was discussed in detail in the present study.

Keywords

metal inert gas welding / aluminum / magnesium / microstructure / mechanical property

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