Microstructural Evolution in ER8 Steel during Hot Deformation: A Cellular Automaton Study
摘要
To study the dynamic recrystallization (DRX) of ER8 wheel steel under hot working conditions, isothermal compression tests were performed. These tests utilized a Gleeble-3500 thermomechanical simulator across a temperature spectrum of 1223K to 1523K and strain rates between 0.001 and 1 s−1. The experimental results provided the foundation for establishing both a constitutive model and a kinetics model describing the DRX behavior of ER8 wheel steel. The material parameters required for cellular automaton (CA) simulations were determined, and a model incorporating dislocation density, recrystallized grain nucleation, and grain growth was developed. Furthermore, by integrating topological deformation techniques, a topology-based cellular automaton dynamic recrystallization model (T-CA) was constructed. This model effectively simulated the microstructural evolution of ER8 wheel steel across a range of strain rates, various temperatures, and differing levels of deformation. The simulation results were compared with physical experiments using optical microscopy (OM) and electron backscatter diffraction (EBSD), demonstrating that the model accurately predicts the DRX behavior of ER8 wheel steel during hot deformation. The austenite transformation behavior of ER8 wheel steel elucidated in this study, together with the validated CA model, provides a reliable theoretical framework and data support for predicting and controlling microstructural evolution during thermomechanical deformation.