An internal state variable approach to modelling microstructural evolution during thermomechanical processing

摘要

During industrial hot working operations, thevarying local thermomechanical histories can be accuratelycomputed by finite element modelling, but their consequencesare not yet incorporated in microstructural evolution models.This paper considers dislocation density, subgrain size andsubgrain boundary misorientation as internal state variables,which control flow stress and subsequent staticrecrystallisation kinetics and recrystallised grain size of singlephase alloys. A simple physical model, based on the concept of"random" and "geometrically necessary" dislocations,indicates that under transient deformation conditions theevolution of each variable is interrelated, and this has important consequences.