ASTM G39-99(2021)
(Practice)Standard Practice for Preparation and Use of Bent-Beam Stress-Corrosion Test Specimens
Standard Practice for Preparation and Use of Bent-Beam Stress-Corrosion Test Specimens
SIGNIFICANCE AND USE
5.1 The bent-beam specimen is designed for determining the stress-corrosion behavior of alloy sheets and plates in a variety of environments. The bent-beam specimens are designed for testing at stress levels below the elastic limit of the alloy. For testing in the plastic range, U-bend specimens should be employed (see Practice G30). Although it is possible to stress bent-beam specimens into the plastic range, the stress level cannot be calculated for plastically-stressed three- and four-point loaded specimens as well as the double-beam specimens. Therefore, the use of bent-beam specimens in the plastic range is not recommended for general use.
SCOPE
1.1 This practice covers procedures for designing, preparing, and using bent-beam stress-corrosion specimens.
1.2 Different specimen configurations are given for use with different product forms, such as sheet or plate. This practice is applicable to specimens of any metal that are stressed to levels less than the elastic limit of the material, and therefore, the applied stress can be accurately calculated or measured (see Note 1). Stress calculations by this practice are not applicable to plastically stressed specimens.
Note 1: It is the nature of these practices that only the applied stress can be calculated. Since stress-corrosion cracking is a function of the total stress, for critical applications and proper interpretation of results, the residual stress (before applying external stress) or the total elastic stress (after applying external stress) should be determined by appropriate nondestructive methods, such as X-ray diffraction (1).2
1.3 Test procedures are given for stress-corrosion testing by exposure to gaseous and liquid environments.
1.4 The bent-beam test is best suited for flat product forms, such as sheet, strip, and plate. For plate material the bent-beam specimen is more difficult to use because more rugged specimen holders must be built to accommodate the specimens. A double-beam modification of a four-point loaded specimen to utilize heavier materials is described in 10.5.
1.5 The exposure of specimens in a corrosive environment is treated only briefly since other practices deal with this aspect, for example, Practices D1141, G30, G36, G44, G50, and G85. The experimenter is referred to ASTM Special Technical Publication 425 (2).
1.6 The bent-beam practice generally constitutes a constant strain (deflection) test. Once cracking has initiated, the state of stress at the tip of the crack as well as in uncracked areas has changed, and therefore, the known or calculated stress or strain values discussed in this practice apply only to the state of stress existing before initiation of cracks.
1.7 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.
1.8 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. (For more specific safety hazard information see Section 7 and 12.1.)
1.9 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.
General Information
Standards Content (Sample)
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: G39 −99 (Reapproved 2021)
Standard Practice for
Preparation and Use of Bent-Beam Stress-Corrosion Test
1
Specimens
ThisstandardisissuedunderthefixeddesignationG39;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope stress at the tip of the crack as well as in uncracked areas has
changed,andtherefore,theknownorcalculatedstressorstrain
1.1 This practice covers procedures for designing,
valuesdiscussedinthispracticeapplyonlytothestateofstress
preparing, and using bent-beam stress-corrosion specimens.
existing before initiation of cracks.
1.2 Differentspecimenconfigurationsaregivenforusewith
1.7 The values stated in SI units are to be regarded as
different product forms, such as sheet or plate. This practice is
standard. The values given in parentheses after SI units are
applicable to specimens of any metal that are stressed to levels
providedforinformationonlyandarenotconsideredstandard.
less than the elastic limit of the material, and therefore, the
1.8 This standard does not purport to address all of the
applied stress can be accurately calculated or measured (see
safety concerns, if any, associated with its use. It is the
Note 1). Stress calculations by this practice are not applicable
responsibility of the user of this standard to establish appro-
to plastically stressed specimens.
priate safety, health, and environmental practices and deter-
NOTE 1—It is the nature of these practices that only the applied stress
mine the applicability of regulatory limitations prior to use.
canbecalculated.Sincestress-corrosioncrackingisafunctionofthetotal
(For more specific safety hazard information see Section 7 and
stress, for critical applications and proper interpretation of results, the
residual stress (before applying external stress) or the total elastic stress 12.1.)
(after applying external stress) should be determined by appropriate
1.9 This international standard was developed in accor-
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nondestructive methods, such as X-ray diffraction (1).
dance with internationally recognized principles on standard-
1.3 Test procedures are given for stress-corrosion testing by
ization established in the Decision on Principles for the
exposure to gaseous and liquid environments.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
1.4 The bent-beam test is best suited for flat product forms,
Barriers to Trade (TBT) Committee.
suchassheet,strip,andplate.Forplatematerialthebent-beam
specimen is more difficult to use because more rugged speci-
2. Referenced Documents
men holders must be built to accommodate the specimens. A
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double-beam modification of a four-point loaded specimen to 2.1 ASTM Standards:
utilize heavier materials is described in 10.5. D1141Practice for the Preparation of Substitute Ocean
Water
1.5 The exposure of specimens in a corrosive environment
G30 Practice for Making and Using U-Bend Stress-
is treated only briefly since other practices deal with this
Corrosion Test Specimens
aspect, for example, Practices D1141, G30, G36, G44, G50,
G36Practice for Evaluating Stress-Corrosion-Cracking Re-
and G85. The experimenter is referred to ASTM Special
sistance of Metals and Alloys in a Boiling Magnesium
Technical Publication 425 (2).
Chloride Solution
1.6 The bent-beam practice generally constitutes a constant
G44PracticeforExposureofMetalsandAlloysbyAlternate
strain (deflection) test. Once cracking has initiated, the state of
Immersion in Neutral 3.5 % Sodium Chloride Solution
G50Practice for Conducting Atmospheric Corrosion Tests
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This practice is under the jurisdiction ofASTM Committee G01 on Corrosion
on Metals
of Metals and is the direct responsibility of Subcommittee G01.06 on Environmen-
tally Assisted Cracking.
Current edition approved May 1, 2021. Published May 2021. Originally
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approvedin1973.Lastpreviouseditionapprovedin2016asG39–99(2016).DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/G0039-99R21. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
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The boldface numbers in parentheses refer to a list of references at the end of Standards volume information, refer to the standard’s Document Summary page on
this standard. the ASTM website.
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G39 − 99 (2021)
G85Pract
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