A grain scale approach for modeling steady-state discontinuous dynamic recrystallization

Discontinuous dynamic recrystallization (DDRX) generally occurs in low-stacking-fault-energy metals. New grains nucleate and grow at the expense of the strain-hardened older grains. A steady-state flow stress independent of initial conditions is experimentally observed. A general model is proposed to describe these phenomena. While the transient behavior can be addressed only numerically, a steady state is described in detail by closed-form relationships. The approach includes strain hardening and dynamic recovery, nucleation, growth and shrinkage of grains. Furthermore, the strain-hardening equation can be supplemented to account for the effect of boundary-migration-induced softening (BMIS). The present paper first states the general equations of the model some simple strain-hardening laws neglecting BM IS are then discussed. Finally, a method for evaluating the material parameters is described and illustrated by the example of 304L stainless steel. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.