Grain size effects on plastic strain and dislocation density tensor fields in metal polycrystals

International audienceA strain gradient crystal plasticity model is used to explore the grain size effect on the fields of plastic strain and of the dislocation density tensors in two-dimensional polycrystals. Finite element simulations are performed for several aggregates of 24 and 52 grains with a detailed description of the intragranular fields. It is found that the increasing energy cost associated with the development of geometrically necessary dislocations (GNDs) leads to the formation of a network of intense slip bands accommodating the imposed deformation in ultra-fine grain polycrystals