High-resolution characterisation of austenitic stainless steel in PWR environments: Effect of strain and surface finish on crack initiation and propagation

Abstract

Initiation and propagation of cracks under simulated primary water conditions and different slow strain rates have been studied for an austenitic 304-type stainless steel. Two surface finishes were used to better understand the conditions that trigger stress corrosion cracking (SCC). The main objective is to identify the mechanism(s) that govern the initiation and propagation of SCC and the influence of microstructure. Crack morphology, stress localisation and local chemical composition were characterized for all samples studied. The characterization methodology includes scanning electron microscopy (SEM), 3D focused ion beam (FIB), Transmission Kikuchi Diffraction (TKD), and analytical scanning transmission electron microscopy (STEM).