Intergranular stress corrosion crack growth of sensitized type 304 stainless steel in a simulated boiling-water reactor environment

Stress corrosion cracking (SCC) of type 304 (UNS S30400) stainless steel (SS) was studied using fracture mechanics-type standard compact tension (CT) specimens in simulated boiling-water reactor (BWR) environments at 288 degrees C. Tests were performed under constant loading. Crack lengths and crack growth rates (CGR) were determined by the reverse direct current (DC) potential drop method. Fractography was used to determine the mode of cracking and to confirm validity of the potential drop method for crack length determination Test environments were high-purity deionized water with < 10 ppb to 440 ppb dissolved oxygen (O-2) O ppb to 570 ppb hydrogen peroxide (H2O2), and 14 ppb to 150 ppb dissolved hydrogen (H-2). CGR were found to be 4.9 x 10(-8) mm/s to 3.0 x 10(-7) mm/s at an initial stress Intensity (K) of 31 MP root m (100 kgf/mm(1.5) in simulated normal water chemistry (NWC), However the CGR was < I x 10(-9) mm/s in simulated hydrogen water chemistry (HWC). CGR decreased with decreasing corrosion potential (E-corr). The critical potential below which SCC growth did not occur was < similar to -200 mV(SHE).