Crystal-plasticity-based FE modelling of a dual-phase microstructure in which grains have non-uniform shape and size

Melchior, Maxime [UCL] Remacle, Jean-François [UCL] Delannay, Laurent [UCL]

Different modelling approaches are tested for the prediction of plastic heterogeneity of a dual-phase polycrystalline microstructure. A novel technique is proposed for the generation of finite element (FE) meshes offering a more realistic representation of the grain topology in 3D. The model microstructure consists of a primary phase with regular grain shapes, and a secondary phase, characterised by a smaller average grain size, located preferentially at the triple junctions. In order to reduce computational cost, the FE mesh is coarse within the grains and fine at the interfaces. A specifically designed coarsening procedure is used to ensure that the mesh remains periodic in 3D. Initial grain orientations are generated such that they constitute a statistically representative sampling of the global texture while accounting for the non-uniform grain size. Compared to other modelling strategies including the conventional Taylor model and FE modelling with grains shaped as bricks or as truncated octahedrons, the new method yields a more accurate prediction of the strain partitioning between the two phases and the macroscopic texture development in a multiphase steel.