The correlation between mechanical and electrochemical parameters of stress corrosion cracking of austenitic stainless steels

Extension measurements of exposed specimens of austenitic stainless steels in hot magnesium chloride solutions are interpreted with the potential-time curves. For austenitic stainless steels, it is very difficult to determine the yield point; it is necessary to study the stress-elongation curves at different elongation rates and to known the creep behaviour of the steels. In dead load stress corrosion tests the elongation-time curves allow the incubation time of stress corrosion cracks to be distinguished from the propagation time. The propagation time is more important than incubation time for the classification of the susceptibility of austenitic stainless steels to stress corrosion cracking, because the incubation time is more dependent on experimental procedure than is the propagation time. The stainless steel classification obtained was compared with a new test in which a load is applied and immediately taken off; after a rapid fall the potential-time behaviour provides information about the crack velocity.