The influence of grain orientation on the stored energy during cold rolling of steels - experimental evidence and finite element simulations

In order to understand the role of the stored energy within individual grains of a deformed polycrystal during the nucleation step of recrystallization, a finite element code has been used to characterise in some details the deformed state of an aggregate of grains after rolling. This code takes explicitly into account the crystallographic nature of the material, and includes a physically-based hardening law of individual slip systems, enabling us to calculate an average dislocation density within each grain after each deformation step. The presented simulations of large plane strain deformation have been performed on an aggregate of 343 cubic grains, asociated with 343 initially randomly distributed orientations. It is thus possible to follow during deformation the global texture and deformation evolutions and also to get more local information within deformed grains, such as reorientations, average intra and intercrystalline misorientations and dislocation densities. It is thus found that the predicted texture evolution is in good agreement with the experimental one measured after various rolling strains; also, at the end of the simulated rolling process, the so-called γ orientations are predicted to be the hardest, i. e. associated with maximum dislocation density. This result is finally discussed, together with preliminary calculations of intragranular misorientations in the context of nucleation