Predicting Multiple Peak Dynamic Recrystallization of Copper

Abstract

Abstract. The relationship between the initial grain size and the critical Zener-Hollomon parameter value ( D 0 -Z c ) defines the conditions for which a material will dynamically recrystallize with a single or with multiple peaks. The relationship between the stable dynamically recrystallized grain and the Zener-Hollomon parameter ( D rex -Z ) predicts the conditions for grain refinement or coarsening during dynamic recrystallization. The Relative-Grain-Size model ( D 0 -Z c and D rex -Z ) adequately predicts the type of hot flow behavior before reaching a stable dynamically recrystallized grain size. However, a model to reliably predict the stress-strain curve is still needed. Several models exist which have been shown to predict the transition from single to multiple peak stresses. Nevertheless few of them report real material parameters and in any case the computational time makes them unviable for any industrial simulation process. The present authors have devised a DRX algorithm to measure the stress due to the diminishing initial grain volume and to measure the correction stress due to recrystallizing grains. One stress contribution is produced as a result of the surrounding or percolating new grains and another stress is due to the response of deforming the initial grain volume. The present authors propose a relatively simple model that in conjunction with existing theories for dynamic recovery can quantitatively predict the transition from single to multiple peak stress behavior during dynamic recrystallization. The predicted stress-strain curves have been correlated to experimental results after compression testing (650oC-950oC) commercially 99.9% pure copper.