Investigation of dynamic recrystallization and modeling of microstructure evolution of an Al-Mg-Si aluminum alloy during high-temperature deformation

The dynamic recrystallization (DRX) behavior and microstructure evolution of an Al-Mg-Si aluminum alloy (AA6N01) during hot deformation are investigated by experiments and mathematical modeling. Based on hot compression tests under different strain rates and temperatures, the type of dynamic recrystallization are firstly investigated by EBSD analysis. It is observed that DRX occurs under all examined conditions, however, the type of DRX is associated with the deformation temperature at the strain level of about 1.5. Then considering the deformed and recrystallized behaviors, a grain size evolution model is established to predict the microstructure evolution during hot deformation. (1) According to the dislocation work hardening theory, the DRX kinetic model is built to predict the distribution of DRX. (2) Taking the effects of deformation temperature and strain rate into account, the DRX grain size model is built to predict the equiaxed recrystallized grain size. (3) By combining the experimental observations with numerical simulation, the deformed grain size model is established to predict the elongated grain size evolution. Finally, by integrating above three models, the grain size evolution model is established to predict the microstructure evolution of AA6N01 during high-temperature deformation and is validated by comparing the predicted grain size with experimental observations during hot compression and hot extrusion, respectively.