Stress Corrosion Cracking of ASTM A508 Cl 2 Steel in Oxygenated Water at Elevated Temperatures

A508 Cl 2 steel has been found to undergo stress corrosion cracking (SCC) in pure water containing 1 or 8 ppm of oxygen at temperatures ranging from 100 to 288 C, as determined using constant extension rate tests (CERTs). At temperatures of 100 and 150 C, cracks nucleate at corrosion pits. At higher temperatures, however, cracks nucleate beneath hematite crystals which grow via a dissolution-precipitation mechanism upon a base oxide film at sites of high anodic dissolution activity. The susceptibility of SCC increases with increasing oxygen concentration, but passes through a maximum as a function of temperature at 250 C.