Estimation of the Critical Potential for Crevice Corrosion by Measuring Metastable Pitting Potential of Stainless Steel in Aqueous Chloride Solution

Abstract

It has been reported that crevice corrosion of stainless steel is accompanied by the generation of micro pits with a diameter of several μm in the crevice. Such micro pits are called metastable pits because they are immediately repassivated on free surfaces without a crevice structure. Metastable pitting potential （V’_{C, MS}） of stainless steel in aqueous solution of pH＝1.0, [Cl^－]＝3.0 mol・dm^－3, which was obtained from anodic polarization, was consistent with the critical potential for the initiation of crevice corrosion （V_{C, CREV}）. Therefore, it was found that the measurement of V’_{C, MS} in the aqueous solution simulating the environment in the crevice when the micro pits are generated is useful for the simple estimation of V_{C, CREV}.