ASTM D7972-14
(Test Method)Standard Test Method for Flexural Strength of Manufactured Carbon and Graphite Articles Using Three-Point Loading at Room Temperature
Standard Test Method for Flexural Strength of Manufactured Carbon and Graphite Articles Using Three-Point Loading at Room Temperature
SIGNIFICANCE AND USE
4.1 This test method provides a framework for material development, quality control, characterization, and design data generation purposes. The user needs to assess the applicability of the method on the specific material and for the intended use, as shown by the interlaboratory study.
4.2 This test method determines the maximum loading on a graphite specimen with simple beam geometry in three–point bending, and it provides a means for the calculation of flexural strength at ambient temperature and environmental conditions.
4.3 The flexure stress is computed based on simple beam theory with assumptions that the material is isotropic and homogeneous, the moduli of elasticity in tension and compression are identical, and the material is linearly elastic. For materials with large grains, the minimum specimen dimension should be significantly larger than the maximum grain size (see Guide D7775).
4.4 Flexural strength of a group of test specimens is influenced by several parameters associated with the test procedure. Such factors include the loading rate, test environment, specimen size, specimen preparation, and test fixtures. Specimen sizes and fixtures should be chosen to reduce errors due to material variability or testing parameters, such as friction and non-parallelism of specimen surfaces.
4.5 The flexural strength of a manufactured graphite or carbon material is dependent on both its inherent resistance to fracture and the size and severity of flaws. Variations in these cause a natural scatter in test results for a sample of test specimens. Fractographic analysis of fracture surfaces, although beyond the scope of this standard, is highly recommended for all purposes, especially if the data will be used for design as discussed in Practices C1239 and C1322.
4.6 The three-point test configuration exposes only a very small portion of the specimen to the maximum stress. Therefore, three-point flexural strengths are likely to be much greater than four-po...
SCOPE
1.1 This test method covers determination of the flexural strength of manufactured carbon and graphite articles using a square, rectangular or cylindrical beam in three-point loading at room temperature.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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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Designation:D7972 −14 AnAmerican National Standard
Standard Test Method for
Flexural Strength of Manufactured Carbon and Graphite
1
Articles Using Three-Point Loading at Room Temperature
This standard is issued under the fixed designation D7972; 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.
1. Scope 3. Terminology
1.1 This test method covers determination of the flexural 3.1 Definitions:
strength of manufactured carbon and graphite articles using a 3.1.1 flexural strength—a measure of the ultimate load
square, rectangular or cylindrical beam in three-point loading carrying capacity of a specified beam in bending.
at room temperature.
3.1.2 grain—in manufactured (synthetic) carbon and
graphite, particle of filler material (usually coke or graphite) in
1.2 The values stated in SI units are to be regarded as
the starting mix formulation. Also referred to as granular
standard. No other units of measurement are included in this
material, filler particle, or aggregate material.
standard.
1.3 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
4.1 This test method provides a framework for material
responsibility of the user of this standard to establish appro-
development, quality control, characterization, and design data
priate safety and health practices and determine the applica-
generation purposes. The user needs to assess the applicability
bility of regulatory limitations prior to use.
of the method on the specific material and for the intended use,
as shown by the interlaboratory study.
2. Referenced Documents
4.2 This test method determines the maximum loading on a
2
2.1 ASTM Standards:
graphite specimen with simple beam geometry in three–point
C78 Test Method for Flexural Strength of Concrete (Using
bending, and it provides a means for the calculation of flexural
Simple Beam with Third-Point Loading)
strength at ambient temperature and environmental conditions.
C559 Test Method for Bulk Density by Physical Measure-
4.3 The flexure stress is computed based on simple beam
ments of Manufactured Carbon and Graphite Articles
C1161 Test Method for Flexural Strength of Advanced theory with assumptions that the material is isotropic and
homogeneous, the moduli of elasticity in tension and compres-
Ceramics at Ambient Temperature
C1239 Practice for Reporting Uniaxial Strength Data and sion are identical, and the material is linearly elastic. For
materials with large grains, the minimum specimen dimension
Estimating Weibull Distribution Parameters forAdvanced
Ceramics shouldbesignificantlylargerthanthemaximumgrainsize(see
Guide D7775).
C1322 Practice for Fractography and Characterization of
Fracture Origins in Advanced Ceramics
4.4 Flexural strength of a group of test specimens is
D7775 Guide for Measurements on Small Graphite Speci-
influenced by several parameters associated with the test
mens
procedure. Such factors include the loading rate, test
E4 Practices for Force Verification of Testing Machines
environment, specimen size, specimen preparation, and test
E691 Practice for Conducting an Interlaboratory Study to
fixtures. Specimen sizes and fixtures should be chosen to
Determine the Precision of a Test Method
reduce errors due to material variability or testing parameters,
such as friction and non-parallelism of specimen surfaces.
4.5 The flexural strength of a manufactured graphite or
1
This test method is under the jurisdiction of ASTM Committee D02 on
carbon material is dependent on both its inherent resistance to
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
fracture and the size and severity of flaws. Variations in these
Subcommittee D02.F0 on Manufactured Carbon and Graphite Products.
cause a natural scatter in test results for a sample of test
Current edition approved Dec. 1, 2014. Published February 2015. DOI: 10.1520/
D7972-14.
specimens. Fractographic analysis of fracture surfaces, al-
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
though beyond the scope of this standard, is highly recom-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
mended for all purposes, especially if the data will be used for
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. design as discussed in Practices C1239 and C1322.
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D7972−14
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