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Modeling of microstructure development during hot deformation and subsequent annealing of precipitates containing AA6016
Microstructure and microchemistry evolution during hot deformation and subsequent annealing of a commercial Al-Mg-Si alloy were experimentally investigated using electron backscatter diffraction (EBSD) and SEM. Meanwhile, a through-process model framework consisting of the deformation model GIA-3IVM+ and the recrystallization (RX) model CORe was utilized to simulate the microstructure evolution during the processing. Based on the experimental observations a new model for the RX driving force in particular after hot deformation and its evolution during subsequent annealing is proposed. Unlike a driving force model for cold deformed materials proposed recently, the geometrically necessary dislocations (GNDs) are taken into account in the new model for hot deformed materials, in which the deformation stored energy is normally very low. Furthermore, the static recovery of statistical stored dislocations, which decreases the RX driving force, is terminated in the new model at a certain level. This is based on the fact that after evolving into subgrain boundaries, dislocation cell walls will no longer change (apart from very slow subgrain growth). Fine precipitates exhibit back-driving forces on the moving grain boundary, namely the Zener drag force. This diminishes the effective driving force for RX in the deformed grains. Implementing these aspects into the RX model CORe, the partial RX in materials deformed at two variant conditions could be modeled. The predicted microstructural results are consistent with the experimental observation in terms of RX kinetics, recrystallized grain structure and size, and recrystallized volume fraction.