Prediction of the critical conditions for dynamic recrystallization in the austenitic steel 800H

Engineering approaches to model dynamic recrystallization (DRX) explicitly assume the existence of a critical strain for DRX. However, DRX is not set off at a certain “critical” amount of strain, rather is initiated by reaching critical conditions for microstructural instability. It was proposed recently that these critical conditions can be expressed in terms of a point of inflection on the θ(σ) curve, where σ is the flow stress and θ is the hardening rate. A theoretical framework is presented to predict these critical conditions on the basis of a dislocation work hardening model. Once tuned to a specific hardening curve the model allows to predict the onset of DRX for different temperatures and strain rates, and, in principle, for changing materials chemistry.