Sub Grain Formation in Plastically Deformed Microstructures in the Combined Simulation of Rolling and Annealing for Static Recrystallization with the Phase-Field Method

摘要

The microstructure and the mechanical properties of cold rolled metal sheets after annealing strongly depend on the prior deformation step and the recrystallization process. To obtain a recrystallized microstructure after annealing, we simulate the recrystallization and sub grain formation process for plastically deformed microstructures, considering crystallographic orientations and deformation with the phase-field method. The first step is the conversion of the simulation data for a rolling process which is calculated with the finite element method (FEM) on an irregular grid. These data are subsequently projected on a regular grid to simulate the static recrystallization with the phase-field method. Before the misorientation between discretisation points can be used to generate sub grains, the data of the FE simulation must be transferred in an appropriate manner on the regular grid. Voronoi tessellation is a common technique, which is used to map irregular grid points on a regular grid, e.g. in simulation of recrystallization processes with cellular automata [1]. The accumulated plastic slip of the crystal plasticity FE simulation is considered as a measure of the plastic deformation for the recrystallization and is included in the mapping process. Nucleation of sub grains is modeled depending on the deformation of the grain structure and the misorientation of the grain boundary. An additional driving force for the growth of the nuclei during recrystallization is incorporated in the phase-field model [2] by using the accumulated plastic slip (stored energy) as an additional system variable.