Crevice corrosion that cannot be ignored
Thread Content
It is a special form of pitting that occurs in gaps (such as those under welds, rivet joints, gaskets, or deposits); the damage takes the form of grooves, and in severe cases it can lead to penetration. The gap contains an oxygen-deficient area that is also blocked; the pH value inside the gap decreases while the concentration increases. There is often a relatively long incubation period; once the pH value inside the crack drops to a critical level, accelerated corrosion occurs, similar to what happens in pores (Figure --2). It generally occurs most easily in solutions containing Cl-. An effective prevention method is to eliminate gaps.
Crevice corrosion is a phenomenon that commonly occurs in gaps such as those at welds, rivet joints, under gaskets, or beneath accumulations of debris. Due to lack of oxygen and being enclosed, the pH level drops and concentrations increase within these gaps; after a prolonged incubation period, accelerated corrosion takes place, resulting in groove-like damage that may even penetrate the metal. This is particularly severe in solutions containing chloride ions. An effective way to prevent crevice corrosion is to eliminate the crevices. .