Which corrosion is characterized by the exfoliation or flaking of metal layers from the surface?

Which corrosion is characterized by the exfoliation or flaking of metal layers from the surface?

• A. Intergranular Corrosion
• B. Pitting Corrosion
• C. Exfoliation Corrosion
• D. Galvanic Corrosion

Answer: (C)

Exfoliation corrosion describes a peeling or flaking of surface layers caused by corrosion that travels along the grain structure, lifting and separating layers of metal. This gives the surface a flaky, layered appearance as corrosion products push apart the layers between grains. It’s commonly seen in certain wrought aluminum and magnesium alloys in aggressive environments, especially when residual stresses are present. Intergranular corrosion, by contrast, is attack along grain boundaries but doesn’t necessarily result in surface layers peeling off. Pitting corrosion forms tiny pits rather than layered flakes. Galvanic corrosion occurs due to the electrochemical interaction between two different metals in contact, causing preferential attack at one metal, not a peeling of layers.

Exfoliation corrosion describes a peeling or flaking of surface layers caused by corrosion that travels along the grain structure, lifting and separating layers of metal. This gives the surface a flaky, layered appearance as corrosion products push apart the layers between grains. It’s commonly seen in certain wrought aluminum and magnesium alloys in aggressive environments, especially when residual stresses are present.

Intergranular corrosion, by contrast, is attack along grain boundaries but doesn’t necessarily result in surface layers peeling off. Pitting corrosion forms tiny pits rather than layered flakes. Galvanic corrosion occurs due to the electrochemical interaction between two different metals in contact, causing preferential attack at one metal, not a peeling of layers.