Corrosion and Stress Corrosion Crack Initiation in the Machined Surfaces of Austenitic Stainless Steels in Pressurized Water Reactor Primary Water: Research Progress and Perspective

Austenitic stainless steels (ASSs) are important materials which are used widely in the primary circuits of pressurized water reactors (PWRs). The performance of the ASSs in PWR primary water has been outstanding. However, stress corrosion cracking cases have been identified in ASS components in the primary loop of PWR nuclear power plants since the end of 20th century. Most stress corrosion cracking cases occurred in low flow or stagnant zones in the dead-leg regions, where the primary water chemistry was contaminated with anionic impurities. Cold work has been identified to be necessary for stress corrosion cracking for components operating in locations where the water is well circulated. Machining and other surface treatments can always introduce cold work to ASS components. Therefore, considerable research efforts have been invested to understand the nature of the surface deformation layer on ASS introduced during machining processes and by other surface treatments, as well as the corrosion and stress corrosion crack initiation behaviors of the machined surfaces in simulated PWR primary water. This paper reviews the research progress on the surface deformation layer on ASSs introduced by various processes, and the effects of surface deformation on the corrosion and stress corrosion crack initiation behavior of ASSs. The key issues that remain to be solved are summarized, and possible solutions are suggested.