Validation of a model for static and dynamic recrystallization in metals

In this paper, modifications are proposed to a phenomenological plasticity model to account for the evolution of recrystallization and the resultant softening behavior. The novel model includes internal state variables representing dislocation density and the spacing between geometrically necessary subgrain boundaries. In order to capture both single and multiple peak recrystallization, the model tracks the evolution of recrystallized volume fractions for multiple cycles of recrystallization, and has a set of state variables for each volume fraction. A rule of mixtures is used to determine the average stress. The model is capable of capturing static recrystallization as well as both single and multiple peak dynamic recrystallization. Material parameters are fit to data from monotonic compression tests on copper for a wide range of temperatures and strain rates. The model is then validated by using the same parameter set to predict multiple-stage response in which samples are compressed, held at temperature for various lengths of time, and then compressed further. The model predicts both the static recrystallization that occurs between loading stages as well as the dynamic recrystallization occurring during the second loading stage