Three dimensional predictions of grain scale plasticity and grain boundaries using crystal plasticity finite element models

In this work, we use crystal plasticity finite element (CPFE) models of 2D and 3D polycrystalline microstructures to elucidate 3D topological effects on microstructural evolution during rolling deformation. The important capabilities of our CPFE framework are that it predicts not only texture evolution but also the evolution of intra-grain and inter-grain misorientations, grain shape and grain boundary character distribution. These abilities are possible because both grain structures and grain boundary surfaces are explicitly meshed. Both the 2D and 3D models predict heterogeneous deformation within the grains and across the polycrystal. They also predict similar evolution in grain shape and texture. However, we find that the inter-granular misorientations are higher, the intra-granular misorientations are lower, and the texture evolves faster in 3D compared to 2D, differences which increase with strain level. We attribute these growing differences to the fact that in the 3D microstructure, grains are allowed to reorient both in plane and out of plane to preferred orientations, unlike in 2D. Interestingly, we also find that in the 3D model, the frequency of Σ 3 boundaries increases with rolling strain up to the largest strain studied, 1.0. The important 3D effects revealed here can help studies that use CPFE models for understanding microstructural evolution, localization, and damage.