Crystal plasticity modeling of hardening and creep in ferritic-martensitic alloys under thermal and irradiation environments

Abstract

A crystal plasticity constitutive modeling framework is presented to model the inelastic deformation behavior of unirradiated and irradiated ferritic-martensitic steels. The model considers dislocation densities that evolve during inelastic deformation, as well as irradiation-induced defect densities and their sizes, as internal state variables. The model accounts for key deformation mechanisms - dislocation glide and climb - as well as the microstructural effects governing hardening, thermal creep, irradiation hardening, and irradiation creep. The model accounts for the effects of temperature, strain rate, and irradiation dose on hardening, and successfully reproduces the stress and temperature dependence of both thermal and irradiation creep. Validation against multiple experimental datasets confirms that the model predictions fall within the range of experimentally observed variability, particularly in predicting the irradiation-induced hardening and the steady-state creep rates across a wide range of thermal and irradiation conditions. Overall, this work establishes a robust, mechanistic framework for predicting the elevated temperature, irradiation-induced deformation behavior of ferritic-martensitic steels.