Meaning and use
5.1 The test method was originally developed for research and development purposes; However, in specific material specifications, it is referenced to evaluate production materials (see section 14 on accuracy and deviation).

5.2 Using this test method can effectively predict the spalling corrosion behavior of these alloys in various types of outdoor services, especially in Marine and industrial environments. The four-test solution is highly corrosive and represents a more stringent type of environmental service, and certainly does not include unusual chemicals that are unlikely to be encountered in the natural environment.

5.3 Exfoliation grades were chosen arbitrarily in this test to illustrate the wide range of resistance to exfoliation. However, it remains to be determined whether a correlation can be established between EXCO test ratings and the actual conditions of use for a given alloy. The Aluminium Alloy Peeling Corrosion Working Group (G01.05.02.08) is conducting an activity to conduct outdoor exposure testing for this purpose. For example, it has been reported that Al-Zn-Mg-Cu alloy samples rated EA or P in the 48-hour EXCO test did not experience more than a small amount of early peeling (EA) during six to nine years of exposure to the coastal atmosphere, while in most cases ED grade materials showed significant peeling within a year in the coastal atmosphere. It is expected that more comparisons will be provided as outdoor testing expands.

ASTM G34-2020 Test Method for Cyclic Wet Heat Corrosion

Radius
1.1 This test method covers a constant immersion exfoliation corrosion (EXCO) test procedure for high strength 2XXX and 7XXX series aluminum alloys.

Note 1: This test method was originally developed for research and development purposes; However, in specific material specifications, it is referred to as applicable for evaluating production materials (see section 14, “Accuracy and Deviation”).

1.2 This test method is applicable to all forged products, such as sheets, plates, extrusions and forgings produced by conventional ingot metallurgy processes.

1.3 The test method can be used on any form of sample or part that can be immersed in the test solution.

1.4 This standard is not intended to address all safety concerns, if any, associated with its use. It is the responsibility of users of this standard to establish appropriate safety, health and environmental practices and to determine the applicability of regulatory restrictions prior to use.

1.5 This international standard is based on internationally recognized standardization principles established in the Decision on Principles for the Development of International Standards, Guidelines and Recommendations issued by the WTO Committee on Technical Barriers to Trade.