Passivity breakdown and stress corrosion cracking of stainless steel

Passivity breakdown of stainless steel is an important initial process for starting stress corrosion cracking. It was found that small amount of impurities in environments affects the initiation process, but do not affect the propagation process of SCC. The environmental effect on the initiation process is rationally explained by introducing “bound water model” of passive film and HSAB (Hard and Soft Acid and Base) rule. Background of the issue including bound water model and HSAB rule was discussed.