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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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Historical
Publication Date
30-Sep-2018
Current Stage
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ASTM G34-01(2018) - Standard Test Method for Exfoliation Corrosion Susceptibility in 2XXX and 7XXX Series Aluminum Alloys (EXCO Test)
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Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: G34 − 01 (Reapproved 2018)
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.
3
1. Scope ing (Withdrawn 2010)
G112 Guide for Conducting Exfoliation Corrosion Tests in
1.1 This test method covers a procedure for constant im-
Aluminum Alloys
mersion exfoliation corrosion (EXCO) testing of high-strength
2XXX and 7XXX series aluminum alloys.
2.2 ASTM Adjuncts:
4
Illustrations (Enlarged Glossy Prints)
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
3. Terminology
Section 14 on Precision and Bias).
3.1 Definitions:
1.2 This test method applies to all wrought products such as
3.1.1 exfoliation—corrosion that proceeds laterally from the
sheet, plate, extrusions, and forgings produced from conven-
sites of initiation along planes parallel to the surface, generally
tional ingot metallurgy process.
at grain boundaries, forming corrosion products that force
1.3 Thistestmethodcanbeusedwithanyformofspecimen
metal away from the body of the material giving rise to a
or part that can be immersed in the test solution.
layered appearance (Terminology G15).
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Summary of Test Method
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 4.1 This test method provides an accelerated exfoliation
mine the applicability of regulatory limitations prior to use.
corrosion test for 2XXX and 7XXX series aluminum alloys
1.5 This international standard was developed in accor-
that involves the continuous immersion of test materials in a
dance with internationally recognized principles on standard-
solution containing 4 M sodium chloride, 0.5 M potassium
ization established in the Decision on Principles for the
nitrate, and 0.1 M nitric acid at 25 6 3°C (77 6 5°F). The
Development of International Standards, Guides and Recom-
susceptibility to exfoliation is determined by visual
mendations issued by the World Trade Organization Technical
examination, with performance ratings established by refer-
Barriers to Trade (TBT) Committee.
ence to standard photographs.
2. Referenced Documents
5. Significance and Use
2
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).
5.2 Use of this test method provides a useful prediction of
1
This test method is under the jurisdiction of ASTM Committee G01 on
the exfoliation corrosion behavior of these alloys in various
Corrosion of Metals and is the direct responsibility of Subcommittee G01.05 on
types of outdoor service, especially in marine and industrial
Laboratory Corrosion Tests.
Current edition approved Oct. 1, 2018. Published November 2018. Originally
approved in 1972. Last previous edition approved in 2013 as G34 – 01 (2013). DOI:
10.1520/G0034-01R18.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or The last approved version of this historical standard is referenced on
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM www.astm.org.
4
Standards volume information, refer to the standard’s Document Summary page on Available from ASTM International Headquarters. Order Adjunct No.
the ASTM website. ADJG003402. Original adjunct produced in 1980.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
G34 − 01 (2018)
5
environments. The test solution is very corrosive and repre- 7.4 The solution shall be maintained at a temperature of 25
sents the more severe types of environmental service, 6 3°C (77 6 5°F).
excluding, of course, unusual chemicals not likely to be
8. Sampling
encountered in natural environments.
8.1 Sampling procedures are not considered applicable to
5.3 The exfoliation ratings were arbitra
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: G34 − 01 (Reapproved 2013) G34 − 01 (Reapproved 2018)
Standard Test Method for
Exfoliation Corrosion Susceptibility in 2XXX and 7XXX
1
Series Aluminum Alloys (EXCO Test)
This standard is issued under the fixed designation G34; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
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
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
D1193 Specification for Reagent Water
E3 Guide for Preparation of Metallographic Specimens
3
G15 Terminology Relating to Corrosion and Corrosion Testing (Withdrawn 2010)
G112 Guide for Conducting Exfoliation Corrosion Tests in Aluminum Alloys
2.2 ASTM Adjuncts:
4
Illustrations (Enlarged Glossy Prints)
3. Terminology
3.1 Definitions:
3.1.1 exfoliation—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 (Terminology G15).
4. Summary of Test Method
4.1 This test method provides an accelerated exfoliation corrosion test for 2XXX and 7XXX series aluminum alloys that
involves the continuous immersion of test materials in a solution containing 4 M sodium chloride, 0.5 M potassium nitrate, and
1
This test method is under the jurisdiction of ASTM Committee G01 on Corrosion of Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory
Corrosion Tests.
Current edition approved May 1, 2013Oct. 1, 2018. Published July 2013November 2018. Originally approved in 1972. Last previous edition approved in 20072013 as
G34G34 – 01 (2013).–01 (2007). DOI: 10.1520/G0034-01R13.10.1520/G0034-01R18.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The last approved version of this historical standard is referenced on www.astm.org.
4
Available from ASTM International Headquarters. Order Adjunct No. ADJG003402. Original adjunct produced in 1980.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
G34 − 01 (2018)
0.1 M nitric acid at 25 6 3°C (77 6 5°F). The susceptibility to exfoliation is determined by visual examination, with performance
ratings established by reference to standard photographs.
5. 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
5
of outdoor service, especially in marine and indust
...

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