Aluminium alloy exfoliation corrosion (ASSET)

LMATS has been assessed by NATA, Australia to perform a Standard Test Method in accordance with ASTM G66 for Visual Assessment of Exfoliation Corrosion Susceptibility of 5XXX Series Aluminium Alloys (ASSET Test).

ASTM G66 covers a procedure for continuous immersion exfoliation corrosion testing of 5XXX series aluminium-magnesium wrought alloys containing 2.0 % or more magnesium.  In this test, specimens are immersed for 24 h at 65 ±1°C in a solution containing ammonium chloride, ammonium nitrate, ammonium tartrate, and hydrogen peroxide. The susceptibility to exfoliation is determined by visual examination using performance ratings established by reference to standard photographs. By definition, exfoliation is a type of corrosion that proceeds laterally from the sites of initiation along planes parallel to the surface, generally at grain boundaries, forming corrosion products that force metal away from the body of the material, giving rise to a layered appearance.

This test method provides a reliable prediction of the exfoliation corrosion behaviour of Al-Mg alloys in marine environments. The test is useful for alloy development studies and quality control of mill products such as sheets and plates.

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