A clearer view of how crevice corrosion occurs

Crevice corrosion is a poorly understood and very damaging form of corrosion. This paper presents the essential characteristics of crevice corrosion established during the last four decades and some recent results that provide a fresh approach to understanding the process. A simple criterion has been developed that involves two factors. First is the current and resistance between the anodic reaction in the crevice and the cathodic reaction at the outer surface; second is the polarization curve. Practices for preventing crevice corrosion are also discussed. The size of the active peak in the polarization curve and, in particular, whether it increases or decreases can be used to determine whether or not a change in a system parameter (e.g., a solute addition to the alloy) will promote or inhibit crevice corrosion. A second indicator is whether the solution resistivity increases or decreases.