Crystal Plasticity modeling of dynamic recrystallization in CP Ti

Abstract

The present work is an attempt at modeling the phenomenon of dynamic recrystallization (DRX) in commercial purity α-titanium. DRX is associated with increase in number of grains along with loss of strength. Thus it is critical to understand its occurrence while structural metal components and parts are processed. A dislocation density hardening based approach accounts for the occurrence of DRX subject to achieving a critical value of dislocation density for each grain. A model describing nucleation and probability of DRX is integrated into a polycrystal plasticity framework. Only slip deformation modes are considered. In the present work, multiple parametric studies have been carried out. The formation of new DRX grains with deformation has been highlighted. Due to applying a probabilistic criterion for addition of new DRX grains, this number is less than the number of grains having dislocation density more than critical value that is required for occurrence of DRX. The average dislocation density over all grains has been shown to decrease with deformation due to nucleation of new grains. A modified algorithm for modeling dynamic recrystallization has henceforth been demonstrated for CP Ti via evolution of flow stress, dislocation density and grain weights of ‘old’ and ‘new’ grains with deformation.