Modeling and characterization of dynamic recrystallization under variable deformation states

Flexible rolling with variable deformation states has brought new challenges to dynamic recrystallization (DRX) theory based on conventional constant deformation state. Modeling and characterization of DRX are investigated, inspired by the successful application of constitutive models and EBSD technique in the field of characterizing the recrystallization of metallic materials, combined with the characteristics of flow stress. Two constitutive models for constant and transient deformation states were considered. The dynamic recovery effect was integrated into the model for predicting the flow stress and DRX volume fraction. A hot processing map was established to predict the instability region. Various DRX synergistic regulation mechanisms and crystallographic orientation distribution under a transient deformation state were explored. The results suggest that DRX is the main softening characteristic under various deformation states. The predicted flow stress of the constant and transient models are in good agreement with the experimental values. The regulation mechanism of DRX transforms from continuous DRX to discontinuous DRX when the strain rate dynamic decreases. DRX grains display a random orientation distribution, and the crystallographic orientation is toward the 〈111〉 fiber parallel to the normal direction of the compression axis when the DRX volume fraction is high. These findings provide insight into the DRX constitutive description and microstructure evolution under variable deformation states.