Analysis of Local Characteristics and Microstructure of Dissimilar Metal Interface in Scrubbing Refill Friction Stir Spot Welding Joint

Friction stir spot welding (FSSW) is one of the solid state welding methods and dissimilar material joining by FSSW has been investigated. "Scrubbing refill FSSW (Sc-RFSSW)" has developed as a new dissimilar material joining method, and it was shown that Sc-RFSSW provides higher joint strength than conventional FSSW methods in joining the aluminum alloy and non-coated steel. In this study, the microscale testing was performed to evaluate the dissimilar material interfacial strength of Sc-RFSSW joints. The relationship between the interfacial strength distribution and the macroscopic strength of the Sc-RFSSW joint was analyzed. In addition, the microstructure of the dissimilar material interface was observed, and the relationship between the microstructure and the interface strength was shown.