Quantification of SCC mechanisms in austenitic alloys under PWR primary water conditions

In order to achieve a full mechanistic understanding of stress corrosion cracking (SCC), the key operating mechanisms need to be identified but also quantified. In this study, we summarize and rationalize key findings from the last 15 years of high-resolution characterization of SCC in our group. A comprehensive characterization of a set of austenitic alloys with different Ni content and constant Cr level, tested under simulated pressurized water reactor (PWR) primary water conditions at various temperatures, has revealed evidence for at least two operating mechanisms: one diffusion-related and the other deformation-related. For their relevance to the nuclear industry, two additional alloys with increased Cr content were also studied (A800 and A690). Key precursors for SCC initiation and propagation are identified and their effect on alloy degradation discussed. A list of key materials’ properties that ensure low SCC susceptibility is proposed.