Multiscale simulation of irradiation-induced embrittlement in low-Cu RPV steel

Abstract

Irradiation embrittlement critically influences the mechanical performance of low-Cu reactor pressure vessel (RPV) steels, with Mn-Ni-Si precipitates recognized as primary contributors. To elucidate the underlying mechanisms, we establish a multiscale simulation framework that integrates density functional theory (DFT), atomic kinetic Monte Carlo (AKMC), cluster dynamics (CD), and crystal plasticity finite element (CPFE) modeling. First-principles calculations provide vacancy formation energies and migration barriers, which determine solute diffusion kinetics. These parameters are incorporated into a CD model to predict the evolution of precipitate size, number density, and volume fraction under irradiation. The resulting microstructural statistics are then used as inputs to a CPFE model that accounts for dislocation evolution, from which an irradiation-induced hardening law is derived. This approach quantitatively links the evolution of irradiation-induced precipitates to macroscopic yield strength and ductile-to-brittle transition (DBTT) behavior, with predictions validated against available experimental data.