Final answer:
Pitting Corrosion is the uneven attack resulting in metal surface imperfections, where a galvanic cell forms at the anode, leading to oxidation and significant damage usually under protective coatings with less visible warning signs.
Step-by-step explanation:
When metal surfaces experience an uneven and localized attack that leads to imperfections, this type of deterioration is known as Pitting Corrosion. This corrosion process involves the creation of a galvanic cell, with different sites on the metal functioning as anode and cathode. The anode is where the metal is oxidized and corroded. For instance, when iron is exposed to oxygen, holes in a protective coating can allow oxygen to reduce at the surface with greater air exposure, while iron is oxidized to Fe²⁺ (aq) in less exposed areas, forming rust at the anodic site. Pitting corrosion can cause a large pit under a painted surface, often with little visible warning. Protective coatings and cathodic protection are two strategies to prevent this kind of corrosion.