Standard Test Method for Exfoliation Corrosion Susceptibility in 2XXX and 7XXX Series Aluminum Alloys (EXCO Test)
|Publication Date:||29 November 1972|
|ICS Code (Aluminium and aluminium alloys):||77.120.10|
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.2
This method applies only to wrought products such as sheet. plate, extrusions. and forgings.
This method of test can be used with any form of specimen or part that can be immersed in the test solution.
2 Ketcham. Sara J., and Jeffery. Paul W., "Exfoliation Corrosion Testing of 7178 and 7075 Aluminum Alloys" (Report of ASTM G01.05 Interlaboratory Testing Program in Cooperation with the Aluminum Association): and Sprowls. D. O., Walsh. J. D., and Shumaker. M. B., "Simplified Exfoliation Testing of Aluminum Alloys. Localized Corrosion - Cause of Metal Failure. ASTM STP 516. Am. Soc. Testing Masts., 1972.