A two-site mean field model of discontinuous dynamic recrystallization
The paper describes a new model of discontinuous dynamic recrystallization (DDRX) which can operate in constant or variable thermomechanical conditions. The model considers the elementary physical phenomena at the grain scale such as strain hardening, recovery, grain boundary migration, and nucleation. The microstructure is represented through a set of representative grains defined by their size and dislocation density. It is linked to a constitutive law giving access to the polycrystal flow stress. Interaction between representative grains and the surrounding material is idealized using a two-site approach whereby two homogeneous equivalent media with different dislocation densities are considered. Topological information is incorporated into the model by prescribing the relative weight of these two equivalent media as a function of their volume fractions. This procedure allows accounting for the well-known necklace structures. The model is applied to the prediction of DDRX in 304. L stainless steel, with parameters identified using an inverse methodology based on a genetic algorithm. Results show good agreement with experimental data at different temperatures and strain rates, predicting recrystallization kinetics, recrystallized grain size and stress-strain curve. Parameters identified with one initial grain size lead to accurate results for another initial grain size without introducing any additional parameter. © 2011 Elsevier B.V.
Keywords: Constitutive law ; Discontinuous dynamic recrystallization ; Dislocation densities ; Dynamic recrystallization ; Experimental data ; Grain boundaries ; Grain boundary migration ; Grain boundary migrations ; Grain size and shape ; Initial grain size ; Inverse methodology ; Mean field models ; Mean field theory ; Modelling ; New model ; Nucleation ; Physical phenomena ; Recrystallization kinetics ; Recrystallized grains ; Relative weights ; Stainless steel ; Stainless steels ; Strain hardening ; Strain rate ; Stress-strain curves ; Surrounding materials ; Thermo-mechanical ; Topological information ; Topology
Record created on 2014-11-14, modified on 2016-08-09