In situ monitoring of crevice corrosion morphology of Type 316L stainless steel and repassivation behavior induced by sulfate ions

To analyze the repassivation mechanism induced by SO42− ions, in situ monitoring of the crevice corrosion morphology on Type 316L stainless steel was performed. The repassivation of the crevice corrosion was observed when the solution was changed from 1 M NaCl to 0.88 M Na2SO4 or to 1 M NaCl-0.88 M Na2SO4. The active dissolution of Type 316L stainless steel was suppressed by SO42− ions at pH 0.4 in anodic polarization measurements. The transition from active to passive states inside the crevice was likely promoted by SO42− ions.