On the dependence of in-grain subdivision and deformation texture of aluminum on grain interaction

Abstract

We present plane strain simulations about the dependence of orientational in-grain subdivision and crystallographic deformation textures in aluminum polycrystals on grain interaction. The predictions are compared to experiments. For the simulations we use a crystal plasticity finite element and different polycrystal homogenization models. One set of finite element simulations is conducted by statistically varying the arrangement of the grains in a polycrystal. Each grain contains 8 integration points and has different neighbor grains in each simulation. The reorientation paths of the 8 integration points in each grain are sampled for the different polycrystal arrangements. For quantifying the influence of the grain neighborhood on subdivision and texture we use a mean orientation concept for the calculation of the orientation spread among the 8 originally identical in-grain orientation points after plastic straining. The results are compared to Taylor–Bishop–Hill-type and Sachs-type models which consider grain interaction on a statistical basis. The study reveals five important points about grain interaction. First, the consideration of local grain neighborhood has a significant influence on the reorientation of a grain (up to 20% in terms of its end orientation and its orientation density), but its own initial orientation is more important for its reorientation behavior than its grain neighborhood. Second, the sharpness of the deformation texture is affected by grain interaction leading to an overall weaker texture when compared to results obtained without interaction. Third, the in-grain subdivision of formerly homogeneous grains occurring during straining is strongly dependent on their initial orientation. For instance some crystals build up in-grain orientation changes of more than 20° after 95% straining while others do practically not subdivide. Fourth, the dependence of in-grain subdivision on the neighbor grains is different for crystals with different initial orientation (cube or rotated Goss grains reveal strong subdivision). Fifth, the upper bound for the variation of texture due to changes in grain neighborhood amounts at most to 5% in terms of the positions of the main texture components. In terms of the overall orientation density all predictions (using different neighborhood configurations) remain within a narrow tube with an orientation scatter of 10% (β-fiber) to 20% (Brass component, α-fiber)) when the neighborhood changes.