Pitting corrosion is a wet corrosion process that occurs in the presence of an electrolyte, such as water containing chloride ions or other aggressive anions. It involves the localized breakdown of a metal’s passive protective film, leading to the formation of deep, narrow pits.
Key Characteristics:
- Electrolyte Required: Occurs in moist environments — especially where water contains chlorides, acids, or salt spray.
- Localized Attack: Creates small, highly concentrated corrosion sites that can penetrate metal surfaces.
- Common Environments: Found in marine systems, chemical plants, heat exchangers, and humid or coastal regions.
- Material Susceptibility: Affects materials like 304 stainless steel, aluminum alloys, and brass without proper alloying or protection.
Because pitting relies on wet electrochemical conditions, prevention strategies include protective coatings, drainage design, chloride control, and using pitting-resistant alloys like 316 stainless steel or duplex steels.