Coupled quantitative modeling of microstructural evolution and plastic flow during continuous dynamic recrystallization

Continuous dynamic recrystallization (cDRX) dominates microstructural evolution during the hot working of metallic materials with high stacking fault energy (SFE), such as aluminum alloys. However, in reality, a lack of quantitative and visual modeling of the process hinders its wide-spread application in the hot working process. In this study, using a recently developed multilevel cellular automaton (MCA) that integrates the newly established cell switching rules and topology deformation technique, a novel mesoscale MCA-cDRX model was constructed to investigate the evolution of both microstructures and macroscopic mechanical response in the hot working of AA7075 aluminum alloy. By considering the evolution of dislocation density and the orientation angle of the local cells as the primary clues, the plastic flow, recrystallization kinetics, features of subgrain size and high-angle grain boundaries, and influence of initial matrix characteristics on the cDRX mechanism were analyzed. The model predictions are consistent with the experimental data. Quantitative analysis confirms that the incubation time for the initiation of subgrain for-mation is significantly short. The fine-grain matrix and high initial volume fraction of low-angle grain boundaries can significantly accelerate the progress of cDRX owing to a stronger accumu-lation of dislocations in the dislocation cell walls through the climb and cross-slip mechanisms in the deformed aluminum alloy. The subgrain size is dependent on the Zener-Hollomon parameter. The developed simulation framework offers an effective means to allow the visualization of the cDRX.

Automated summary

In this study, a novel mesoscale MCA-cDRX model was constructed to investigate the evolution of microstructures and mechanical response during the hot working of AA7075 aluminum alloy. The analysis shows that the initial matrix characteristics have a significant impact on the cDRX mechanism, and the subgrain size is dependent on the Zener-Hollomon parameter.