Refill Friction Stir Spot Welding Al Alloy to Copper via Pure Metallurgical Joining Mechanism

Abstract The current investigation of refill friction stir spot welding (refill FSSW) Al alloy to copper primarily involved plunging the tool into bottom sheet achieve both metallurgical and mechanical interfacial bonding. Compared conventional FSSW pinless FSSW, weld strength can be significantly improved by using this method. Nevertheless, wear is a critical issue during FSSW. In study, defect-free Al/copper dissimilar welds were successfully fabricated only top sheet. Overall, two types continuous ultra-thin intermetallic compounds (IMCs) layers identified at whole interface. Also, strong evidence melting resolidification was observed in localized region. peak temperature obtained center interface 591 °C, heating rate reached up 916 °C/s sleeve penetration phase. A softened region produced via process, hardness profile exhibited W-shaped appearance along middle thickness alloy. lap shear load insensitive condition, whose scatter rather small. fracture path exclusively propagated IMCs layer Cu 9 4 under external loadings, CuAl 2 detected on fractured surface side. This research indicated that acceptable achieved pure joining mechanism, which has significant potential for industrial applications.