2021 Volume 70 Issue 1 Pages 10-17
In this study, we investigated the corrosion behavior of steel in a crevice by immersion tests in NaCl solution to propose a model of lap-joint corrosion of steel. The crevice was prepared by placing a crevice former above a steel plate. The crevice geometry was controlled by the radius of the crevice former and the distance between the crevice former and the steel. The results of the immersion test showed that corrosion morphology and corrosion weight loss of the steel depended on the crevice geometry. The corrosion potential of the steel during the immersion slightly depended on the crevice geometry and was in the diffusion-limiting region of oxygen reduction reaction. These results revealed that the corrosion of the steel proceeds by the formation of differential aeration inside and outside of the crevice, where the steel surface inside the crevice acts as an anode and the remaining steel surface outside the crevice acts as a cathode. Furthermore, it was shown that the corrosion weight loss evaluated by FEM analysis of dissolved oxygen concentration was consistent with the trend obtained experimentally in this study.