Relationship between crack propagation rate and dissolution rate of type 310 stainless steel in H2SO4-NaCl solution

Relationship between crack propagation rate and dissolution rate of type 31 0 stainless steel was studied to clarify the effect of the lattice defects on crack initiation and crack propagation in H2SO4-NaCl solutions. Stress corrosion morphology changed in order of general corrosion, localize d corrosion, stress corrosion cracking with increasing NaCl concentration. Stress corrosion cracking was observed at the potential range of active reg ion on an anodic polarization curve. Dissolution rates of prestrained speci mens were increased with increasing the dislocation density. Optical microg raph showed the formation of corrosion grooves and dissolution rates of the se corrosion grooves are close to the crack propagation rates under low ini tial stress intensity. Transmission electron microscopic observation showed the existence of bundle structure that is high dislocation density region like a plane. As the dissolution rate was accelerated with increasing the d islocation density, this corrosion grooves might be formed by the preferent ial dissolution of bundle structure. From these results, it is thought that the crack initiation and the propaga tion are accelerated with preferential dissolution of bundle structure.