Localised corrosion is corrosion that occurs in specific spots rather than evenly across the whole exposed surface. It can arise where conditions are more aggressive in one location (crevice corrosion) or where the protective passive film is damaged or defective. These forms can combine, for example pits forming inside a crevice, which then accelerates the corrosion.
Common forms of localised corrosion include:
- Pitting on a boldly exposed surface
- Corrosion in a creviced region shielded from the bulk environment
- Intergranular corrosion of an alloy with a susceptible grain boundary region
- Exfoliation corrosion, a form of intergranular corrosion that pries apart elongated grains with a voluminous grain boundary corrosion product