Intergranular stress distributions in polycrystalline aggregates of irradiated stainless steel

TL;DR

This study uses finite element simulations with validated crystal plasticity models to analyze intergranular stress distributions in irradiated stainless steel, aiding predictions of stress corrosion cracking in nuclear reactors.

Contribution

It introduces a physically-based crystal plasticity approach to predict intergranular stresses in irradiated stainless steel, validated for neutron-irradiated conditions.

Findings

Intergranular normal stress distributions follow a master curve when scaled by macroscopic stress.

Distributions are insensitive to free surface effects, relevant for IGSCC.

Stress distributions increase with irradiation level and plastic strain.

Abstract

In order to predict InterGranular Stress Corrosion Cracking (IGSCC) of post-irradiated austenitic stainless steel in Light Water Reactor (LWR) environment, reliable predictions of intergranular stresses are required. Finite elements simulations have been performed on realistic polycrystalline aggregate with a recently proposed physically-based crystal plasticity constitutive equations validated for neutron-irradiated austenitic stainless steel. Intergranular normal stress probability density functions are found with respect to plastic strain and irradiation level, for uniaxial loading conditions. In addition, plastic slip activity jumps at grain boundaries are also presented. Intergranular normal stress distributions describe, from a statistical point of view, the potential increase of intergranular stress with respect to the macroscopic stress due to grain-grain interactions. The distributions are shown to be well described by a master curve once rescaled by the macroscopic stress, in the range of irradiation level and strain considered in this study. The upper tail of this master curve is shown to be insensitive to free surface effect, which is relevant for IGSCC