In metallurgy, exfoliation corrosion (also called lamellar corrosion[1]) is a severe type[2] of intergranular corrosion that raises surface grains from metal by forming corrosion products at grain boundaries under the surface. It is frequently found on extruded sections where grain thickness is not as thick as the rolled grain. It can affect aircraft structures,[citation needed] marine vessels, heaters [1] and other objects.