Microstructure and tensile strength of aluminum/stainless steel joint welded by inertia friction and continuous drive friction

Microstructure and mechanical properties of 6061-T6 aluminum alloy/304 stainless steel (Al/steel) joints welded by inertia friction (IFW) and continuous drive friction (CDFW) were studied comparatively. Morphology, microstructure, interfacial composition, and mechanical properties of Al/steel joints were investigated. Results showed that an intermetallic compound (IMC) reaction layer was formed at the welding interface in the CDFWed joint, and wider and clearer than that of the IFWed joint. The high concentration Si was observed at the welding interface. The grain of fully dynamic recrystallized zone (FDRZ) was below 0.1 μm in both joints, and the average width of FDRZ in the IFWed joint and CDFWed joint was about 5 μm and 2 μm, respectively. FDRZ had the high hardness, and the hardness value of IFWed joint was higher than that of CDFWed joint. The maximum tensile strength of IFWed joint was higher than that of CDFWed joint, and the reason should be related to the thickness of IMC at the welding interface.