Abstract
Formulating appropriate simulation models that capture the microstructure evolution at the mesoscale in metals undergoing thermomechanical treatments is a formidable task. In this work, an approach combining higher-order dislocation density based crystal plasticity with a phase-field model is used to predict microstructure evolution in deformed polycrystals. This approach allows to model the heterogeneous reorientation of the crystal lattice due to viscoplastic deformation and the reorientation due to migrating grain boundaries. The model is used to study the effect of strain localization in subgrain boundary formation and grain boundary migration due to stored dislocation densities. It is demonstrated that both these phenomena are inherently captured by the coupled approach.
Highlights
A metallic polycrystal exposed to thermomechanical treatment can undergo significant microstructural evolution due to viscoplastic deformation and subsequent or concurrent recrystallization processes
Summary and conclusions Microstructure evolution in deformed polycrystals is studied in this work by finite element simulations, applying a constitutive model that combines Cosserat single crystal plasticity with a phase-field model
A major result is the importance of strain localization and curvature localization on subsequent grain boundary formation and grain boundary migration
Summary
A metallic polycrystal exposed to thermomechanical treatment can undergo significant microstructural evolution due to viscoplastic deformation and subsequent or concurrent recrystallization processes. In order to create extended frameworks which take into account grain boundary migration after deformation, and in some cases nucleation as an intermediate step, several authors have coupled crystal plasticity models with methods such as cellular automata [12,13], level-sets [14,15] or phase-field methods [16,17,18,19,20] (these references are by no means a complete list but should rather be considered a sample of works for each mentioned approach). A fully coupled, thermodynamically consistent model that combines a Cosserat single crystal plasticity model with the modified KWC orientation phase-field model of [26] is used to predict microstructure evolution in deformed polycrystals. Because the KWC model represents the lattice orientation as a continuous field rather than relying on a cellular description of the grains, it can accommodate the heterogeneous reorientation associated with plastic slip processes.
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