Modeling of surface dynamic recrystallisation during the finish turning of the 15-5PH steel

摘要

Modelling surface microstructural changes is a key issue when considering the manufacture of critical metallic parts. During machining, extreme conditions of temperature and deformation appear in the cutting zone. Consequently, surface microstructure is strongly affected with a direct impact on its integrity and the fatigue resistance of the part. Thus the machining effect on the 15-5PH steel surface has been underlined. To explain and predict the formation of this modified surface layer, the dynamic recrystallization (DRX) has been considered. Firstly, a DRX model has been identified using dynamic compressive tests. The calibrated DRX model is composed of two parts: a criterion of initiation and an evolution law. EBSD maps obtained from compressed samples show recrystallized microstructures comparable with micrographys of machined surface. Then, the DRX model has been implemented in an ALE orthogonal cutting model. Numerical simulation results predict the recrystallized layer at the machined surface. The DRX proportion rapidly decreases from 100% at the surface to 0% at few micrometers depth. So, experimental observations are successfully reproduced.