Austenitic stainless steels are known to be resistant to generalized corrosion in high temperature and high pressure water representative of pressurized water reactor (PWR) primary water. Nevertheless, there are some conditions which can induce stress corrosion cracking (SCC) like off-normal water chemistry (chlorides, ..) or high level of residual stresses. Many parameters can influence the SCC behaviour of austenitic alloys, including what is called a heat-to-heat variability. Even if this heat-to-heat variability has been extensively studied for nickel base alloys used in primary water, there are far less results for austenitic stainless steels. In this context, the objective of this study is to better understand which parameters related to material chemical composition and / or microstructure could modify the SCC susceptibility. Different materials will be studied regarding their surface oxidation and grain boundary oxidation which are of great importance for the SCC crack initiation behavior.
Deep characterizations will be performed with a focus on the microstructure and chemical heterogeneities. Corrosion and stress corrosion cracking tests will be performed in simulated PWR primary water with a focus on the first cracking stages.
This study will permit to identify which parameters have to be taken into account to improve life duration modelling.