Non-uniformity of intermetallic compounds and properties in inertia friction welded joints of 2A14 Al alloy to 304 stainless steel

Abstract

Abstract Inertia friction welding (IFW) is attracting considerable attention in recent years for dissimilar metals joining such as aluminum (Al) alloy to stainless steel due to its ease to control heat input accurately. As a result of thermo-mechanical conditions, the microstructure at the friction interface, especially the brittle IMCs, is usually considered to be non-uniformly distributed. In the present study, the non-uniformity of IMCs at different interfacial regions in the IFWed joint and the diffusion bonded joint was comparatively studied by annealing experiments with tensile tests conducted accordingly for quantitatively evaluating the influence of IMCs thickness on the bonding properties. Following the heat treatment, unlike diffusion bonded joints, different growth behavior of IMCs at different interfacial positions of the IFWed joint was observed, which deviated with a varying degree from the parabolic diffusion law. The phenomenon indicated a non-uniform distribution of energy storage along friction interface after welding, resulting from the unique thermo-mechanical conditions in the friction welding process. Moreover, the highest bonding strength appeared at the central interface region where no obvious IMCs layer was founded in the as-welded joint, and a negative correlation between IMCs thickness layer and bonding strength was observed. Therefore, for designing a high-performance Al/steel IFWed joint, the distribution and the corresponding thickness of IMCs should be carefully considered.