The initiation of environmentally assisted cracking in BWR high temperature water

The initiation of environmentally assisted cracking (EAC) usually takes a long time in LWR high temperature water. To understand where EAC tends to initiate and how it initiates, i.e. the initiation mechanism, would be significant in proactively preventing harmful deep cracks and to the development of materials of high EAC resistance. The initiation of EAC from stainless steel specimens with work hardened surface layers in simulated boiling water reactor (BWR) high temperature water has been proposed to be a repeating process of oxidation / film rupture based on a previous work of ours. The work hardened surface layer and local stress concentrations, e.g. at a scratch site, were shown to influence the EAC initiation. Meanwhile, in that work, the role of slip bands is required to be made clear to further the understanding of the development of crack embryos. Those slip bands were already introduced by the applied tensile stress. The present work was focused on specimens without work hardened surface layers. The surface oxide film rupture (just rupture-like) was examined by TEM. It was shown that slip bands are not obviously sensitive to EAC in high temperature water. Factors affecting EAC initiation in BWR high temperature water were discussed.