Microstructure of the interface between aluminum alloy and galvannealed steel plates jointed by FSSW multi-step loading process

Abstract When joining between GA980 and A6061 plates by the FSSW, brittle intermetallic compounds and Zn-contained region are formed at the joint interface. These local reaction products determine the strength of the joint. Therefore, the bonding interface microstructure analysis is crucial to control the process and improve strength. This study performed microstructural analysis near the joint interface on GA980/A6061 joints bonded by the FSSW. The detailed variation of the IMC thickness along with the bonded interface and the microstructure of the Zn-contained region in A6061 plate was clarified. In the A6061 plate, a simple shear texture was observed with the Al <110> direction in the tool rotational direction and the Al {111} plane perpendicular to the direction of the elongated grains. In elongated Al grains surrounded by high-angle grain boundaries, the grains were divided by the low-angle grain boundaries.