Work hardening model based on multiple dislocation densities

Abstract

A variant of the 3IVM (three internal variables model) [F. Roters, D. Raabe, G. Gottstein, Acta Mater. 48 (2000) 4181–4189] is presented. It utilizes the microstructural state variables to describe the plastic flow behavior of cell forming metals and alloys. The internal variables are the six categories of dislocation densities: the mobile edge and screw dislocation densities ( ρ e m , ρ s m ), the immobile edge and screw dislocation densities in the cell walls ( ρ e w , ρ s w ) and the immobile dislocation densities in the cell interiors ( ρ e i , ρ s i ). The inclusion of screw dislocations and their ability to cross slip contributes to enhanced dynamic recovery, particularly at low temperatures and high strain rates. Results will be presented on how the model can be used to calculate the stress–strain curves for various temperatures and strain rates. For the same set of optimising parameters, the predicted flow curves for a variety of strain rates and temperatures are in good agreement with experiments. A particular advantage of this model is that its output can directly be used as input for subsequent recovery and recrystallisation models.