LAUSR

Abstract The stress corrosion cracking behavior of alloy 600 was studied in high temperature water at 288°C to 360°C. The effects of dissolved oxygen (DO) and dissolved hydrogen (DH) on crack growth rate (CGR) are discussed. Results show that the CGR of alloy 600 in hydrogenated water (at the Ni/NiO phase boundary) is about 2-200 times higher than in 2 ppm O2 oxygenated water at 325°C and 360°C, while the opposite behavior was observed at 288°C. Much more severe intergranular oxidation was observed at the crack tips after testing in DH water than in DO water at 325°C and 360°C. The good correlation between CGR and intergranular selective oxidation suggests that the peak CGRs in DH water might be attributed to the combined contribution of instability of the oxides and intergranular selective oxidation at the crack tip during the phase transition.