A dislocation-based model for the substructure evolution and flow stress of aluminum alloys during high-temperature compression

Abstract

The microstructure evolution of aluminum alloys during plastic deformation is a complex metallurgical process controlled by interacting physical mechanisms, such as recovery, continuous dynamic recrystallization (CDRX), and substructure evolution. The present study proposes a dislocation-based model framework to describe the microstructural evolution of dislocation density, subgrain size, misorientation angle, and flow stress. The wall dislocation density is modeled on the basis of the average subgrain size and misorientation evolution. The dislocation density and substructure evolution are independently simulated and compared with electron back- scatter diffraction (EBSD) experimental results. Their mechanisms are thoroughly discussed. The decrease in low- angle subgrain size and the increase in the misorientation angle of subgrain boundaries with increasing strain rate, as well as their evolution with temperature and strain rate, are well reproduced over a wide range of large strains. Furthermore, the evolution of these experimental substructures is employed to model other related mechanical properties. The framework is successfully applied and validated for AA1050 and AA5052 aluminum alloys across different deformation conditions.