A thermomechanical analysis of the localization process at the microstructure scale of a 316L stainless steel

Polycrystalline metallic materials are made of an aggregate of grains more or less well-oriented, with respect to the loading axis, for plastic gliding. Under mechanical loading, this leads to a heterogeneous deformation at the microstructure scale. This local plasticity triggers a heterogeneous thermal dissipation caused by mechanical irreversibilities. Some original experimental works enabling the simultaneous determination of thermal and strain fields, in the same area, at this scale have already been realized in house on a A316L steel. Two complementary ways have now to be followed: some numerical treatments in order to access experimental dissipations and the development of a consistent constitutive model. Both aspects are presented in this communication and a dialogue between micro structural texture coming from EBSD analysis, local deformation mechanism and thermal localization phenomenon is introduced. More particularly, the numerical implementation in a FE code of a fully coupled crystalline plasticity constitutive model has been realized. It enables to compare local kinematic and thermal fields during monotonic tests and to study the heterogeneity of the stored energy at grain scale. These analyses of thermomechanical couplings at the grain scale could lead to the definition of new thermodynamically based strain localization criteria.