Exfoliation Corrosion
Layer corrosion is a form of intergranular corrosion where metal peels off in leaf-like layers parallel to the surface. This coarsens the microstructure and can significantly impair mechanical properties.
Physical-Chemical Mechanism of Action
Layer corrosion occurs in anisotropic metals where the metal peels in thin layers parallel to the surface. This happens due to the attraction of ions and molecules at the crystal lattice, leading to a coarsening of the microstructure.
Metallurgical Relevance & Welding Risks
Layer corrosion can significantly impair the mechanical properties of a material by coarsening the microstructure and reducing strength. This increases susceptibility to cracks and fractures. In welded joints, this can lead to uneven deformation or loss of mechanical properties.
Workshop Practice & Action Guidelines
To avoid layer corrosion, it is important to treat the weld so that it cools evenly. This can be achieved through proper cooling control. When selecting a welding process, use metals with isotropic microstructures or avoid environmental conditions that lead to strongly anisotropic corrosion.