The stress corrosion cracking behaviour of annealed 316 stainless steel in low oxygen 5 ppm chloride content water at 300°C

Stress corrosion cracking tests on annealed 316 stainless steel in water containing 5 ppm Cl− and <5 ppb O2 at 300°C have been conducted at a strain rate of 1.8 × 10−6 s−1. The tests were performed in a low flow rate refreshed autoclave loop under potentiostatic control. Stress corrosion cracking of the steel in 300°C water occurred in two ranges of electrochemical potential; >100 mV and −200 to −450 mV (SHE). The mechanism of stress corrosion cracking in the two potential ranges was anodic dissolution controlled. Crack initiation in the potential range −200 to −450 mV resulted from the presence of a thick magnetite film. The initiation and propagation of stress corrosion cracks in these water conditions is discussed; it is concluded that the surface state of the material is important in determining whether stress corrosion cracks are formed during slow strain rate tests.