This paper addresses the many conceptual similarities that exist among structural materials subject to environmentally assisted cracking in high temperature water. While cracking has been viewed as a highly mechanistically and phenomenologically unique process for every material, temperature, environment, loading, etc., there is an increasingly strong basis for treating environmental crack advance processes of ductile alloys in hot water from a common mechanistic and predictive perspective. This paper addresses the roles of various materials (ranging from low alloy and carbon steels, to stainless steels, to high nickel alloys), water chemistries (e.g., including various BWR and PWR conditions), temperature (from <200 to >360°C), irradiation, etc. on the crack advance process. Viewed from the perspective of the crack tip system, differences once perceived as large (e.g., in corrosion potential for BWRS vs. PWRS) are now recognized as relatively small (e.g., crack advance always occurs at ‘‘low” potential associated with deaerated water (because of oxygen depletion in the crack). Additionally, since these materials rely on good passivity, and since creep increases with temperature, the importance to crack advance of film rupture and metal dissolution / repassivation is common to all of these cracking systems. While unique aspects must be acknowledged and modeled for specific materials (e.g., MnS dissolution in low alloy steels, thermal sensitization, irradiation effects) and specific water chemistries (e.g., etlects of high sulfide levels, occluded chemistries, nickel metal stability at high H2 fugacity), the recognition of the broad similarities and the existence of a common underlying framework leads to a more complete understanding of and predictive approaches for environmentally assisted cracking in high temperature water.
Keywords: Stress corrosion cracking, light water reactors, stainless steel, Alloy 600, high temperature water, predictive modeling, water chemistry, crack growth rate.