Towards a modelling of RPV steel brittle fracture using crystal plasticity computations on polycrystalline aggregates

In the frame of the multi-scale approach of the fracture toughness prediction defined in the PERFECT project, we proposed a new crystal plasticity model and applied it to the computation of stress heterogeneities within a reference polycrystalline aggregate defined in the project RPV material. The proposed crystal plasticity model is able to take into account the effects of temperature and irradiation hardening. The analysis of the results of aggregate computations shows that the distributions of the maximum values of the maximal principal stresses are found to be well described by a Gumbell function. Applying these distributions on a Griffith criterion allows settling the basis of an original fracture criterion. However the increasing resistance to fracture of the steel with temperature can be reproduced only by introducing a temperature dependence of the fracture energy.