A model of continuous dynamic recrystallization

During continuous dynamic recrystallization (CDRX), which occurs in high stacking fault energy metals, new grains are formed by the progressive increase of low-angle boundary misorientations. A simple CDRX model is proposed, that deals with a set of “crystallites” delimited partly by low-angle (LABs) and partly by high-angle (HABs) boundaries. Strain hardening and dynamic recovery are described by the Laasraoui-Jonas equation, which has been modified to take HAB migration into account. Recovery occurs in two ways, viz. by the condensation of dislocations into new LABs, and the absorption of dislocations in the pre-existing boundaries, which leads to the transformation of LABs into HABs. The predictions of the model are presented for both the transient and steady states, including stress-strain curves at various temperatures and strain rates, as well as the associated evolutions of the microstructural parameters such as crystallite sizes, dislocation densities and LAB misorientation distributions. The effect of HAB migration on these parameters is emphasized.