Exfoliation Corrosion
Layer corrosion is a form of intergranular corrosion where the material propagates along lamellar structures parallel to the surface. This causes flaking of the material due to volume increase from corrosion products.
Physicochemical Mechanism of Action
Layer corrosion occurs when a chemical reaction takes place at specific spots of the material with the surrounding medium. This leads to local flaking and the formation of a corrosion layer that spreads parallel to the surface.
Metallurgical Relevance & Welding Risks
Layer corrosion can lead to cracks and deformation in the material. It enlarges the material and can impair mechanical properties. Susceptibility to layer corrosion increases with missing or insufficient surface treatment.
Workshop Practice & Action Guidelines
To avoid layer corrosion, take the following steps:
• Use a clean surface before welding.
• Apply a suitable surface treatment (e.g., sandblasting).
• Make sure the welding process is done correctly and temperature control is maintained.