Which corrosion form is an advanced form of intergranular corrosion, where layers peel away?

Which corrosion form is an advanced form of intergranular corrosion, where layers peel away?

• A. Uniform Surface Corrosion
• B. Intergranular Corrosion
• C. Exfoliation Corrosion
• D. Pitting

Answer: (C)

Exfoliation describes corrosion that progresses along grain boundaries and causes the material between those grains to separate and lift away as thin sheets, so the surface appears to peel. In intergranular attack the metal is corroding along the boundaries between grains, and in this advanced form the weakening is so extensive that layers of material separate and shed from the surface, often looking like peeled or onion-skin layers. This is especially common in certain wrought aluminum alloys used in aerospace, where the layered structure can delaminate under corrosive attack. This differs from uniform surface corrosion, which wears away the surface evenly; pitting, which forms small holes; and basic intergranular corrosion, which attacks along grain boundaries but doesn’t necessarily produce peeling layers.

Exfoliation describes corrosion that progresses along grain boundaries and causes the material between those grains to separate and lift away as thin sheets, so the surface appears to peel. In intergranular attack the metal is corroding along the boundaries between grains, and in this advanced form the weakening is so extensive that layers of material separate and shed from the surface, often looking like peeled or onion-skin layers. This is especially common in certain wrought aluminum alloys used in aerospace, where the layered structure can delaminate under corrosive attack.

This differs from uniform surface corrosion, which wears away the surface evenly; pitting, which forms small holes; and basic intergranular corrosion, which attacks along grain boundaries but doesn’t necessarily produce peeling layers.