Study of plastic flow on intermetallic compounds formation in friction welding of aluminum alloy to stainless steel

Abstract During friction welding of Al alloy to steel, the metallurgical reaction of Al and Fe can be occurred under the coupling effect of heat and rotational plastic flow. However, the detailed role of them in contributing intermetallic compounds (IMCs) development remains largely unknown, causing the significant impediment in further tailoring IMCs. In this regard, a thermal compression bonding process was elaborately designed to highlight the influence of frictional flow on the formation of IMCs in friction welding. From the results, it was revealed in friction welding process, frictional flow significantly promoted the formation of sub-micron sized IMCs along weld interface, since in thermal compression bonded specimens, a significantly thinner IMCs were confirmed. Due to the non-uniform distribution of heat and plastic flow rate at different regions along interface, an inhomogeneous distribution of IMCs in terms of thickness was also identified in friction welded joint. Additionally, the frictional flow and stirring effect of Al alloy also resulted in the convex on friction surface at steel side stripped into Al alloy, enhancing the appearance of IMCs particles. Therefore, frictional plastic flow was supposed to predominately contribute to the growth of IMCs in friction welding of Al alloy to steel.