Film rupture model for aqueous stress corrosion cracking under constant and variable stress intensity factor

A film rupture model for aqueous stress corrosion cracking is developed and used to predict kinetics of crack growth under constant and variable stress intensity factor. The model predicts that creep is necessary for sustained crack growth and creep rate limits crack velocity for constant K and dK/da loading. Contrary to recent thinking, the crack tip strain due to crack advance is viewed as a result, not a cause of crack growth. The crack tip strain gradient elevates and maintains crack tip stress as the crack propagates, which enables creep and sustained crack growth. The model provides a basis for understanding effects of positive and negative K - variation on crack growth.