Microstructure and mechanical properties of dissimilar inertia friction welding of 7A04 aluminum alloy to AZ31 magnesium alloy

Abstract

The dissimilar joints between 7A04 aluminum alloy rod and AZ31 magnesium alloy rod were produced by inertia friction welding. The effects of friction pressure on microstructure and mechanical properties of the joints were investigated. Results showed that intermetallic compounds (IMCs), mainly Al12Mg17 and Al3Mg2, were formed at the interfaces. A large amount of microcracks were generated in IMCs interlayer. The thickness of IMCs layer decreased significantly with increasing friction pressure. The mechanical properties were assessed by tensile test and microhardness. The mechanical properties of joints largely lies on the characteristic of IMCs interlayers at the interface. The tensile strength of the joints increases remarkably with increasing friction pressure. The maximum tensile strength of 96 MPa was achieved under the friction pressure of 124 MPa. All the tensile specimens failed in quasi-cleavage fracture mode along the boundary between IMCs interlayer and Al base metal.