The preferred corrosion of internal layers
of a material can occur if individual structural constituents, e.g. grains or grain boundaries, have been plastically deformed during processing. Also, rolled-in slag lines or segregations can cause
layer corrosion. Layer-type corrosion takes place, by which the material is torn open in strips.
Metallographic section through a layer-type corrosion
on rolled-in segregations in the base material