Abstract
Effect of some alloy elements on the susceptibility of austenitic stainless steels to stress corrosion cracking was investigated by transmission electron microscopy. Thin-foil specimens of the steels were used to examine corrosion behavior before and after exposure to solutions which should cause stress corrosion cracking.
18-8 stainless steels seemed to have high stress corrosion susceptibility at the maximum solubility rof carbon (0.08% C). Dislocation arrangements were dependent on the relative contents of carbon and titanium in the steels containing titanium, but addition of molybdenum had no pronounced effect. Stainless steels containing nitrogen had a planar arrangement of dislocations. In 18-8 and 18-20 austenitic stainless steels containing both elements of nitrogen and carbon, dislocation distributions were dependent on relative contents of them.
Chemical attack was observed in highly restricted slip steps. It was possible that solute atoms segregated to slip planes with moving of dislocations and excess vacancies created during deformation. The solute atoms, therefore, should be concentrated on the slip planes. Stress corrosion, once initiated at slip steps, would be advanced into the interior of the steel by galvanic corrosion.
