ASTM G34-01(2013)
(Test Method)Standard Test Method for Exfoliation Corrosion Susceptibility in 2XXX and 7XXX Series Aluminum Alloys (EXCO Test)
Standard Test Method for Exfoliation Corrosion Susceptibility in 2XXX and 7XXX Series Aluminum Alloys (EXCO Test)
SIGNIFICANCE AND USE
5.1 This test method was originally developed for research and development purposes; however, it is referenced, in specific material specifications, as applicable for evaluating production material (refer to Section 14 on Precision and Bias).
5.2 Use of this test method provides a useful prediction of the exfoliation corrosion behavior of these alloys in various types of outdoor service, especially in marine and industrial environments.5 The test solution is very corrosive and represents the more severe types of environmental service, excluding, of course, unusual chemicals not likely to be encountered in natural environments.
5.3 The exfoliation ratings were arbitrarily chosen to illustrate a wide range in resistance to exfoliation in this test. However, it remains to be determined whether correlations can be established between EXCO test ratings and realistic service conditions for a given alloy. It is an ongoing activity of the Task Group on Exfoliation Corrosion of Aluminum Alloys (G01.05.02.08) to maintain outdoor exposure tests for this purpose. For example, it has been reported6 that samples of Al-Zn-Mg-Cu alloys rated EA or P in a 48-h EXCO test did not develop more than a slight amount of incipient exfoliation (EA) during six- to nine-year exposures to seacoast atmospheres, whereas, ED rated materials in most cases developed severe exfoliation within a year in the seacoast atmosphere. It is anticipated that additional comparisons will become available as the outdoor tests are extended.
SCOPE
1.1 This test method covers a procedure for constant immersion exfoliation corrosion (EXCO) testing of high-strength 2XXX and 7XXX series aluminum alloys. Note 1—This test method was originally developed for research and development purposes; however, it is referenced, in specific material specifications, as applicable for evaluating production material (refer to Section 14 on Precision and Bias).
1.2 This test method applies to all wrought products such as sheet, plate, extrusions, and forgings produced from conventional ingot metallurgy process.
1.3 This test method can be used with any form of specimen or part that can be immersed in the test solution.
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.
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Standards Content (Sample)
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Designation: G34 − 01 (Reapproved 2013)
Standard Test Method for
Exfoliation Corrosion Susceptibility in 2XXX and 7XXX
1
Series Aluminum Alloys (EXCO Test)
ThisstandardisissuedunderthefixeddesignationG34;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 2.2 ASTM Adjuncts:
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Illustrations (Enlarged Glossy Prints)
1.1 This test method covers a procedure for constant im-
mersion exfoliation corrosion (EXCO) testing of high-strength
3. Terminology
2XXX and 7XXX series aluminum alloys.
3.1 Definitions:
NOTE 1—This test method was originally developed for research and
3.1.1 exfoliation—corrosion that proceeds laterally from the
development purposes; however, it is referenced, in specific material
sites of initiation along planes parallel to the surface, generally
specifications, as applicable for evaluating production material (refer to
at grain boundaries, forming corrosion products that force
Section 14 on Precision and Bias).
metal away from the body of the material giving rise to a
1.2 This test method applies to all wrought products such as
layered appearance (Terminology G15).
sheet, plate, extrusions, and forgings produced from conven-
4. Summary of Test Method
tional ingot metallurgy process.
4.1 This test method provides an accelerated exfoliation
1.3 Thistestmethodcanbeusedwithanyformofspecimen
corrosion test for 2XXX and 7XXX series aluminum alloys
or part that can be immersed in the test solution.
that involves the continuous immersion of test materials in a
1.4 This standard does not purport to address all of the
solution containing 4 M sodium chloride, 0.5 M potassium
safety concerns, if any, associated with its use. It is the
nitrate, and 0.1 M nitric acid at 25 6 3°C (77 6 5°F). The
responsibility of the user of this standard to establish appro-
susceptibility to exfoliation is determined by visual
priate safety and health practices and determine the applica-
examination, with performance ratings established by refer-
bility of regulatory limitations prior to use.
ence to standard photographs.
2. Referenced Documents
5. Significance and Use
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2.1 ASTM Standards: 5.1 This test method was originally developed for research
D1193 Specification for Reagent Water
and development purposes; however, it is referenced, in
E3 Guide for Preparation of Metallographic Specimens specific material specifications, as applicable for evaluating
G15 Terminology Relating to Corrosion and Corrosion Test-
productionmaterial(refertoSection14onPrecisionandBias).
3
ing (Withdrawn 2010)
5.2 Use of this test method provides a useful prediction of
G112 Guide for Conducting Exfoliation Corrosion Tests in
the exfoliation corrosion behavior of these alloys in various
Aluminum Alloys
types of outdoor service, especially in marine and industrial
5
environments. The test solution is very corrosive and repre-
sents the more severe types of environmental service,
1
This test method is under the jurisdiction of ASTM Committee G01 on excluding, of course, unusual chemicals not likely to be
Corrosion of Metals and is the direct responsibility of Subcommittee G01.05 on
encountered in natural environments.
Laboratory Corrosion Tests.
CurrenteditionapprovedMay1,2013.PublishedJuly2013.Originallyapproved
in 1972. Last previous edition approved in 2007 as G34–01 (2007). DOI:
4
10.1520/G0034-01R13. Available from ASTM International Headquarters. Order Adjunct No.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or ADJG003402. Original adjunct produced in 1980.
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contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Ketcham, S. J., and Jeffrey, P. W., “Exfoliation Corrosion Testing of 7178 and
Standards volume information, refer to the standard’s Document Summary page on 7075AluminumAlloys” (Report ofASTM G01.05 Interlaboratory Testing Program
the ASTM website. in Cooperation with the Aluminum Association); and Sprowls, D. O., Walsh, J. D.,
3
The last approved version of this historical standard is referenced on and Shumaker, M. B., “Simplified Exfoliation Testing of Aluminum Alloys,”
www.astm.org. Localized Corrosion—Cause of Metal Failure, ASTM STP 516, ASTM, 1972.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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G34 − 01 (2013)
5.3 The exfoliation ratings were arbitrarily chosen to illus- 9. Test Specimens
trate a wide range in resistance to exfoliation in this test.
9.1 Specimens may be of any
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