Impact of radiation on corrosion and SCC of austenitic stainless steels

Radiation affects both corrosion and stress corrosion cracking of stainless steels in high temperature water. While a general understanding of the processes is emerging, there are several interesting observations that have yet to be incorporated. Under irradiation, metal loss both by dissolution and oxide formation is reduced compared to the non-irradiated condition. Both radiolysis and radiation damage in the metal play a role in this observation. Regarding SCC, it is now known that the local stress at the grain boundaries at sites of dislocation channel impingement plays a critical role, as does the composition of the surface oxide over the grain boundary. Emerging factors include grain boundary migration and oxidation down the grain boundary. Other factors such as the presence of second phases near grain boundaries and the overall composition of the steel can significantly affect the cracking susceptibility. Still, the low percentage of cracked boundaries suggests additional factors not accounted for. This talk will focus on what is known and what remains to be discovered on the role of irradiation in corrosion and stress corrosion cracking.