Multi-scale Modeling of Crack Propagation

Abstract

Structural materials inside a nuclear reactor are subjected to contact with high-temperature coolant water, and after several decades of operation, cracks begin to grow in these materials which are otherwise resistant to cracks and corrosion. The mechanism of this phenomenon, referred to as "stress corrosion cracking", still remains unclear. In this paper, we present our attempt to identify the mechanism of stress corrosion cracking using numerical simulations, wherein we attempt to validate a hypothetical oxygen embrittlement mechanism. This mechanism involves diffusion of oxygen and embrittlement caused by the oxygen, and its simulation requires integration of oxygen diffusion and crack growth models. This paper presents the basic framework of such an integrated model and some preliminary simulation results, and shows that the integrated model captures the basic properties of stress corrosion cracking such as the rapid increase in the growth rate at the critical stress and its gradual increase above the critical stress.