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) metho d has been developed to simulate the microstructural evolution and the plas tic flow behaviour during thermomechanical processing with DRX. It provides an essential link for multiscale modelling to bridge mesostructural disloc ation activities with microstructural grain boundary dynamics, allowing acc urate predictions of microstructure, plastic flow behaviour, and property a ttributes. Variations of dislocation density and growth kinetics of each dy namically recrystallizing grain (R-grain) were determined by metallurgical relationships of DRX, and the flow stress was evaluated from the average di slocation 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 predi ctions of microstructural evolution and the flow behaviour at various hot w orking conditions agree well with the experimental results for an oxygen fr ee high conductivity (OFHC) copper. It is identified that the oscillation o f the flow stress-strain curve not only depends on thermomechanical process ing parameters (strain rate and temperature) but also the initial microstru cture. The mean size of R-grains is only a function of the Zener-Hollomon p arameter. However, the percentage of DRX is not only related with the Zener -Hollomon parameter, but also influenced by the nucleation rate and the ini tial microstructure. (C) 2001 Acta Materialia Inc. Published by Elsevier Sc ience Ltd. All rights reserved.