ASTM G34-23
(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. 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.
SCOPE
1.1 This test method covers a procedure for constant immersion exfoliation corrosion (EXCO) testing of high-strength 2XXX (see Note 2) 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).
Note 2: Some Al-Cu-Li alloys are registered in the 2xxx family. This test method has been reported as non representative of performance in outdoor atmospheres for various Al-Cu-Li alloys in both as-quenched and artificially aged tempers.2
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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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.
Designation: G34 − 23
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 2. Referenced Documents
3
2.1 ASTM Standards:
1.1 This test method covers a procedure for constant im-
D1193 Specification for Reagent Water
mersion exfoliation corrosion (EXCO) testing of high-strength
E3 Guide for Preparation of Metallographic Specimens
2XXX (see Note 2) and 7XXX series aluminum alloys.
G112 Guide for Conducting Exfoliation Corrosion Tests in
NOTE 1—This test method was originally developed for research and
Aluminum Alloys
development purposes; however, it is referenced, in specific material
G193 Terminology and Acronyms Relating to Corrosion
specifications, as applicable for evaluating production material (refer to
Section 14 on Precision and Bias).
2.2 ASTM Adjunct:
NOTE 2—Some Al-Cu-Li alloys are registered in the 2xxx family. This
Adjunct to G34 Test Method for Exfoliation Corrosion
test method has been reported as non representative of performance in
Susceptibility in 2XXX and 7XXX Series Aluminum
outdoor atmospheres for various Al-Cu-Li alloys in both as-quenched and
2
Alloys (EXCO Test) (Digital PDF illustrations of appear-
artificially aged tempers.
4
ance classifications – 6 glossy photos (B&W))
1.2 This test method applies to all wrought products such as
sheet, plate, extrusions, and forgings produced from conven-
3. Terminology
tional ingot metallurgy process.
3.1 Definitions:
1.3 This test method can be used with any form of specimen
3.1.1 exfoliation corrosion, n—subsurface corrosion that
or part that can be immersed in the test solution.
proceeds laterally from the sites of initiation along planes
parallel to the surface forming corrosion products that force
1.4 This standard does not purport to address all of the
metal away from the body of the material, giving rise to a
safety concerns, if any, associated with its use. It is the
layered appearance resembling the pages of a book (Terminol-
responsibility of the user of this standard to establish appro-
ogy G193).
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4. Summary of Test Method
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4.1 This test method provides an accelerated exfoliation
ization established in the Decision on Principles for the
corrosion test for 2XXX and 7XXX series aluminum alloys
Development of International Standards, Guides and Recom-
that involves the continuous immersion of test materials in a
mendations issued by the World Trade Organization Technical
solution containing 4 M sodium chloride, 0.5 M potassium
Barriers to Trade (TBT) Committee.
nitrate, and 0.1 M nitric acid at 25 °C 6 3 °C (77 °F 6 5 °F).
The susceptibility to exfoliation is determined by visual
examination, with performance ratings established by refer-
1 ence to standard photographs.
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 Dec. 1, 2023. Published December 2023. Originally
ɛ1
3
approved in 1972. Last previous edition approved in 2018 as G34 – 01 (2018) . For referenced ASTM standards, visit the ASTM website, www.astm.org, or
DOI: 10.1520/G0034-23. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
2
Colvin, E. L., and Murtha, S. J., “Exfoliation Corrosion Testing of Al-Li Alloys Standards volume information, refer to the standard’s Document Summary page on
2090 and 2091,” Proceedings of the Fifth International Aluminum-Lithium the ASTM website.
4
Conference, Williamsburg, VA, Materials and Component Engineering Publications Available from ASTM International Headquarters. Order Adjunct No.
Ltd, U.K., March 24–31, 1989, p. 1251. ADJG003402-E-PDF. 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 − 23
5. Significance and Use
NaCl (4.0 M)
KNO (0.5 M)
3
5.1 This
...
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.
´1
Designation: G34 − 01 (Reapproved 2018) G34 − 23
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
ε NOTE—Adjunct description/stock number updated editorially and editorial changes made throughout in November 2020.
1. Scope
1.1 This test method covers a procedure for constant immersion exfoliation corrosion (EXCO) testing of high-strength 2XXX (see
Note 2) 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).
NOTE 2—Some Al-Cu-Li alloys are registered in the 2xxx family. This test method has been reported as non representative of performance in outdoor
2
atmospheres for various Al-Cu-Li alloys in both as-quenched and artificially aged tempers.
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.
2. Referenced Documents
3
2.1 ASTM Standards:
D1193 Specification for Reagent Water
E3 Guide for Preparation of Metallographic Specimens
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 Oct. 1, 2018Dec. 1, 2023. Published November 2018December 2023. Originally approved in 1972. Last previous edition approved in 20132018
ɛ1
as G34 – 01 (2013).(2018) . DOI: 10.1520/G0034-01R18E01.10.1520/G0034-23.
2
Colvin, E. L., and Murtha, S. J., “Exfoliation Corrosion Testing of Al-Li Alloys 2090 and 2091,” Proceedings of the Fifth International Aluminum-Lithium Conference,
Williamsburg, VA, Materials and Component Engineering Publications Ltd, U.K., March 24–31, 1989, p. 1251.
3
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
G34 − 23
G112 Guide for Conducting Exfoliation Corrosion Tests in Aluminum Alloys
G193 Terminology and Acronyms Relating to Corrosion
2.2 ASTM Adjunct:
Adjunct to G34 Test Method for Exfoliation Corrosion Susceptibility in 2XXX and 7XXX Series Aluminum Alloys (EXCO
4
Test) (Digital PDF illustrations of appearance classifications – 6 glossy photos (B&W))
3. Terminology
3.1 Definitions:
3.1.1 exfoliation—exfoliation corrosion, n—subsurface corrosion that proceeds laterally from the sites of initiation along planes
parallel to the surface, generally at grain boundaries, surface forming corrosion products that force metal away from the body of
the material, giving rise to a layered appearance resembling the pages of a book (Terminology G193).
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 0.1 M nitric
ac
...
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