Research Status on Refill Friction Stir Spot Welding of Aluminum Alloy

As an advanced solid-phase welding technology, refill friction stir spot welding (RFSSW) can effectively avoid the inherent defects of liquid-phase welding, and eliminate the keyhole brought by friction stir spot welding.Therefore, it has irreplaceable advantages in the spot connection field of aluminum alloy, magnesium alloy and other light metals, and has attracted extensive attention. After years of development, RFSSW is no longer limited to the early sleeve insertion mode, but many different types and modes have emerged, such as extra filler RFSSW, two-stage RFSSW, etc.The current research status of RFSSW in the field of aluminum alloy welding in recent years was reviewed, involving the basic working principle, the welding process, the microstructure of the joint and the analysis of failure behavior of the joints. It can provide some reference for the process optimization or parameters selection in RFSSW.