Crevices can be formed under deposits of debris or corrosion products.

• A. True
• B. False
• C. Under deposits of debris
• D. Not related to deposits

Answer: (A)

Crevice corrosion happens when a deposit or debris creates a narrow gap that traps electrolyte against the metal surface. In that confined space, oxygen diffusion is limited, so the solution inside the crevice becomes depleted in oxygen and can become acidic and chloride-rich, making the crevice environment more aggressive than the surrounding metal. This difference drives localized metal dissolution, so crevices under deposits of debris or corrosion products are a common and expected form of corrosion. Cleaning away deposits and avoiding buildup helps prevent these crevices from forming or growing.