FE modelling of microstructure evolution during friction stir spot welding in AA6082-T6

Friction stir spot welding (FSSW) is a solid-state joining method, which is a variant of friction-stir welding. Microstructure analysis shows that the FSSW joint contains four different zones, namely the stir zone, thermo-mechanical affected zone, heat-affected zone and base metal, respectively. In this paper, the results of a FE analysis of the FSSW process of AA6082-T6 considering geometric dynamic recrystallization are presented. A physically based model taking into account three internal state variables was implemented into the commercial FE package DEFORM-3D to describe the microstructure evolution during FSSW. This model allows predicting the dislocation density, grain size, temperature, effective strain, and strain rate during FSSW. The microstructure in stir zone was analysed by electron backscattered diffraction. Experimental and simulation results have been compared to validate the model.