Exfoliation

  Exfoliation corrosion is a particular form of intergranular corrosion associated with high strength aluminum alloys. Alloys that have been extruded or otherwise worked heavily, with a microstructure of elongated, flattened grains, are particularly prone to this damage.

Corrosion products building up along these grain boundaries exert pressure between the grains and the end result is a lifting or leafing effect. The damage often initiates at end grains encountered in machined edges, holes or grooves and can subsequently progress through an entire section.