Stress Corrosion Cracking of Ferritic-Martensitic Steels in Simulated Boiling Water Reactor Environment.

Stress corrosion cracking of advanced powder metallurgy technology (APMT) and T91 (UNS K90901, ferritic-martensitic) steels were investigated in the as-received and proton-irradiated conditions in simulated boiling water reactor environment (2 ppm O₂) using constant extension tensile tests at 288°C at a strain rate of 3x10^-7s^-1. Significant stress corrosion cracking was not observed in the as-received condition. A few cracks, perpendicular the loading direction, were observed in the proton-irradiated (5 dpa) specimen of T91. No intergranular fracture was observed on the fracture surfaces of as-received and proton-irradiated specimens of T91. No cracking was observed for APMT in un-irradiated and proton-irradiated (5 dpa) conditions. Results indicate that both APMT and T91 are highly resistant to stress corrosion cracking in a reactor environment and that irradiation to 5 dpa does not appreciably increase susceptibility. [ABSTRACT FROM AUTHOR]