A quantitative analysis has been made on the initiation of crevice corrosion on the following assumption: (1) The pH in crevice is uniquely determined by the total charge passed as passive current, and (2) the crevice pH decreases to depassivation pH at which active dissolution, crevice corrosion, initiates.
The obtained results are summarized in the followings: (1) The chloride-ion concentration and pH in the artificial pit are closely related to the total charge passed as passive current, and (2) depassivation pH is mainly dependent on dissolved oxygen concentration and alloying elements expressed as (Cr%+3Mo%+0.5Ni%).
The quantitative method for the estimation of the incubation time for crevice corrosion is proposed on the basis of passive current density and depassivation pH. A reasonable correlation is found between the incubation time based on the proposed method and that measured for SUS304 and SUS316 stainless steels in sea-water.
