Significance and Use

Although there are ASTM test methods for exfoliation testing, they concentrate on specific procedures for test methodology itself. Existent test methods do not discuss material variables that can affect performance. Likewise they do not address the need to establish the suitability of an accelerated test for alloys never previously tested nor the need to correlate results of accelerated tests with tests in outdoor atmospheres and with end use performance.

This guide is a compilation of the experience of investigators skilled in the art of conducting exfoliation tests and assessing the degree and significance of the damage encountered. The focus is on two general aspects: guides to techniques that will enhance the likelihood of obtaining reliable information, and tips and procedures to avoid pitfalls that could lead to erroneous results and conclusions.

The following three areas of testing are considered: the test materials starting with the as-received sample up through final specimen preparation, the corrosion test procedures including choice of test, inspection periods, termination point, and rating procedures, and analyses of results and methods for reporting them.

This guide is not intended as a specific corrosion test procedure by which to evaluate the resistance to exfoliation of an aluminum alloy product.

This guide is not intended as a basis for specifications, nor as a guide for material lot acceptance.

1. Scope

1.1 This guide differs from the usual ASTM standard in that it does not address a specific test. Rather, it is an introductory guide for new users of other standard exfoliation test methods, (see Terminology G 15 for definition of exfoliation).

1.2 This guide covers aspects of specimen preparation, exposure, inspection, and evaluation for conducting exfoliation tests on aluminum alloys in both laboratory accelerated environments and in natural, outdoor atmospheres. The intent is to clarify any gaps in existent test methods.

1.3 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only.

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

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

G1 Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens

G15 Terminology Relating to Corrosion and Corrosion Testing

G34 Test Method for Exfoliation Corrosion Susceptibility in 2XXX and 7XXX Series Aluminum Alloys (EXCO Test)

G50 Practice for Conducting Atmospheric Corrosion Tests on Metals

G66 Test Method for Visual Assessment of Exfoliation Corrosion Susceptibility of 5XXX Series Aluminum Alloys (ASSET Test)

G85 Practice for Modified Salt Spray (Fog) Testing

G92 Practice for Characterization of Atmospheric Test Sites

Keywords

2XXX aluminum alloys; 5XXX aluminum alloys; 6XXX aluminum alloys; 7XXX aluminum alloys; accelerated test; atmospheric tests; exfoliation corrosion; immersion tests; salt fog (spray) tests; test problems; test procedures; Accelerated aging/testing--corrosion; Aluminum alloys--corrosion testing; Atmospheric corrosion analysis; Corrosion--Al/Al alloys; Exfoliation corrosion; Immersion--corrosion testing; Salt spray (fog) testing;

ICS Code

ICS Number Code 77.120.10 (Aluminium and aluminium alloys)

DOI: 10.1520/G0112-92R09

ASTM International is a member of CrossRef.

ASTM G112