ASTM R0071 - Standard Method of Test for Exfoliation Corrosion Susceptibility in 7XXX Series Copper-Containing Aluminum Alloys (Exco Test) (This is not an approved ASTM standard; available as PDF, only)

1.1 This method describes a procedure for constant immersion exfoliation (Note 1) corrosion testing of high strength 7XXX series aluminum alloys containing 1.2 to 2.8 % copper.

Note 1-The term exfoliation is used to describe that form of corrosion which proceeds laterally from the sites of initiation along planes, generally grain boundaries, parallel to the surface. The resulting corrosion products force the metal upwards giving rise to a layered appearance to the surface.

1.2 This method applies only to wrought products such as sheet, plate, extrusions, and forgings.

1.3 This method of test can be used with any form of specimen or part that can be immersed in the test solution.