Microstructures at the Interface of Al alloy and galvannealed steel jointed by scrubbing refill friction stir spot welding

Abstract

Al alloy sheet and galvannealed steel sheet were joined by Sc-RFSSW, and the bonding process was analyzed by observing the microstructure of the bonded interface. The interface was divided into three regions. Al, Zn, and IMC flowed into the GA steel sheet at the interface produced under the inner and outer circumferences of the tool shoulder. Zn and Fe discharged by the scrubbing process were rolled into Al from the anchor at the interface produced under the outer periphery of the shoulder and expelled from the interface.