Coupled quantitative simulation of microstructural evolution and plastic flow during dynamic recrystallization

A new modelling approach that couples fundamental metallurgical principles of dynamical recrystallization (DRX) with the cellular automaton (CA) method has been developed to simulate the microstructural evolution and the plastic flow behaviour during thermomechanical processing with DRX. It provides an essential link for multiscale modelling to bridge mesostructural dislocation activities with microstructural grain boundary dynamics, allowing accurate predictions of microstructure, plastic flow behaviour, and property attributes. Variations of dislocation density and growth kinetics of each dynamically recrystallizing grain (R-grain) were determined by metallurgical relationships of DRX, and the flow stress was evaluated from the average dislocation density of the matrix and all the R-grains. The growth direction and the shape of each R-grain were simulated using the CA method. The predictions of microstructural evolution and the flow behaviour at various hot working conditions agree well with the experimental results for an oxygen free high conductivity (OFHC) copper. It is identified that the oscillation of the flow stress-strain curve not only depends on thermomechanical processing parameters (strain rate and temperature) but also the initial microstructure. The mean size of R-grains is only a function of the Zener-Hollomon parameter. However, the percentage of DRX is not only related with the Zener-Hollomon parameter, but also influenced by the nucleation rate and the initial microstructure.