Dislocation Density-Based Modeling of Dynamic Recrystallized Microstructure and Process in Friction Stir Spot Welding of AA6082

This work mainly focuses on a series of microstructural analysis and predictions regarding
dynamic recrystallization behavior, change in grain size, and dislocation density. Additionally,
this study includes the shape prediction of the stir zone formed during friction stir spot welding.
Microstructure analysis of the joint reveals that the mechanism of dynamic recrystallization in the
stir zone is geometric dynamic recrystallization. A set of constitutive equations based on dislocation
density is established and implemented in DEFORM-3D software to predict dynamic recrystallization
during friction stir spot welding of AA6082. From the experimental and model predictions, it is
observed that the original microstructure in the stir zone is completely replaced by a recrystallized
fine grained microstructure. There is satisfactory agreement between the experimental grain size
and the simulated results. In addition, the predicted shape of the stir zone fits quite well with the
experimental shape as well.