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Aluminium: O

Oil Staining

Surface staining caused by the partial decomposition during thermal treatment of residual lubricant.

Orange Peel

A roughening, on subsequent cold deformation, of the surface of sheet or strip when the grain size is too coarse. Has the appearance of an orange skin.


Bauxite - A red rock found in the earth's crust, close to the surface. Extracted by open-cast mining it is a very rich ore with a 25% yield.


Any variation from a true circle of the cross section of a round tube, bar or wire.


Artificial ageing treatment at too high a temperature, or for too long a time, after the maximum hardening effect has been achieved. It causes some loss of properties. In some cases it may be a deliberate act, e.g. to improve resistance to stress corrosion or to minimise any further loss of properties in alloys operating at higher temperatures.