Pitting corrosion is best described as which type of attack?

• A. Uniform attack
• B. Localized pits
• C. Erosion
• D. Intergranular attack

Answer: (B)

Pitting corrosion is a localized attack that creates discrete pits on the metal surface, often starting where a protective film breaks down and in environments such as chlorides. The surface may look largely intact, but small openings permit ongoing corrosion that can penetrate deeply. This distinct pattern—small, isolated pits rather than uniform thinning—is what sets pitting apart.

In contrast, a uniform attack wears away the entire surface more or less evenly; intergranular attack progresses along grain boundaries rather to the surface as a whole and along those boundaries; erosion is mechanical wear from flow and turbulence rather than chemical attack.