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ASTM D7775-11

(Guide)

Standard Guide for Measurements on Small Graphite Specimens

Standard Guide for Measurements on Small Graphite Specimens

SIGNIFICANCE AND USE
The purpose of this guide is to report considerations, which should be included in testing nonstandard specimens that lie outside the constraints imposed on size/volume in existing ASTM standards for graphite (noting that there are some generic ASTM standards with no such constraints). These constraints may be real or may be an artifact of the round-robin test program that supported the standard. It is the responsibility of the user to demonstrate that the application of a standard outside any specified constraints is valid and reasonably provides properties of the bulk material from which the nonstandard specimen was extracted.
SCOPE
1.1 This guide covers best practice for properties measurements on small (nonstandard) graphite specimens and requirements for representing properties of the bulk material. This guide is aimed specifically at measurements required on nuclear graphites, where there may be constraints on the geometry or volume of the test specimen, or both.
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.

General Information

Status
Historical
Publication Date
30-Nov-2011
ICS
59.100.20 - Carbon materials
Technical Committee
D02 - Petroleum Products, Liquid Fuels, and Lubricants
Drafting Committee
D02.F0 - Manufactured Carbon and Graphite Products
Current Stage
Ref Project

Relations

Replaced By
ASTM D7775-11e1 - Standard Guide for Measurements on Small Graphite Specimens
Effective Date
01-Dec-2011
Referred By
ASTM C781-20 - Standard Practice for Testing Graphite Materials for Gas-Cooled Nuclear Reactor Components
Effective Date
01-Dec-2011
Referred By
ASTM D8356-20 - Standard Test Method for Sonic Velocity in Manufactured Carbons and Graphite Materials for use in Obtaining Approximate Elastic Constants: Young’s Modulus, Shear Modulus, and Poisson’s Ratio
Effective Date
01-Dec-2011
Referred By
ASTM D8289-20 - Standard Test Method for Tensile Strength Estimate by Disc Compression of Manufactured Graphite
Effective Date
01-Dec-2011
Referred By
ASTM D8255-19 - Standard Guide for Work of Fracture Measurements on Small Nuclear Graphite Specimens
Effective Date
01-Dec-2011
Referred By
ASTM D7846-21 - Standard Practice for Reporting Uniaxial Strength Data and Estimating Weibull Distribution Parameters for Advanced Graphites
Effective Date
01-Dec-2011
Referred By
ASTM D7972-14(2020) - Standard Test Method for Flexural Strength of Manufactured Carbon and Graphite Articles Using Three-Point Loading at Room Temperature
Effective Date
01-Dec-2011
Referred By
ASTM D8091-21 - Standard Guide for Impregnation of Graphite with Molten Salt
Effective Date
01-Dec-2011
Referred By
ASTM C695-21 - Standard Test Method for Compressive Strength of Carbon and Graphite
Effective Date
01-Dec-2011
Referred By
ASTM C714-17 - Standard Test Method for Thermal Diffusivity of Carbon and Graphite by Thermal Pulse Method
Effective Date
01-Dec-2011

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ASTM D7775-11 - Standard Guide for Measurements on Small Graphite Specimens
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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:D7775–11
Standard Guide for
1
Measurements on Small Graphite Specimens
This standard is issued under the fixed designation D7775; 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 tal Frequencies of Carbon and Graphite Materials by Sonic
Resonance
1.1 This guide covers best practice for properties measure-
C748 Test Method for Rockwell Hardness of Graphite
ments on small (nonstandard) graphite specimens and require-
Materials
ments for representing properties of the bulk material. This
C749 Test Method for Tensile Stress-Strain of Carbon and
guide is aimed specifically at measurements required on
Graphite
nuclear graphites, where there may be constraints on the
C769 Test Method for Sonic Velocity in Manufactured
geometry or volume of the test specimen, or both.
Carbon and Graphite Materials for Use in Obtaining
1.2 The values stated in SI units are to be regarded as
Young’s Modulus
standard. No other units of measurement are included in this
C781 Practice for Testing Graphite and Boronated Graphite
standard.
Materials for High-Temperature Gas-Cooled Nuclear Re-
1.3 This standard does not purport to address all of the
actor Components
safety concerns, if any, associated with its use. It is the
C886 Test Method for Scleroscope Hardness Testing of
responsibility of the user of this standard to establish appro-
Carbon and Graphite Materials
priate safety and health practices and determine the applica-
C1161 Test Method for Flexural Strength of Advanced
bility of regulatory limitations prior to use.
Ceramics at Ambient Temperature
2. Referenced Documents
C1259 Test Method for Dynamic Young’s Modulus, Shear
2
Modulus, and Poisson’s Ratio for Advanced Ceramics by
2.1 ASTM Standards:
Impulse Excitation of Vibration
C559 Test Method for Bulk Density by Physical Measure-
E228 Test Method for Linear Thermal Expansion of Solid
ments of Manufactured Carbon and Graphite Articles
Materials With a Push-Rod Dilatometer
C565 Test Methods for Tension Testing of Carbon and
E1461 Test Method for Thermal Diffusivity by the Flash
Graphite Mechanical Materials
Method
C611 Test Method for Electrical Resistivity of Manufac-
tured Carbon and Graphite Articles at Room Temperature
3. Summary of Guide
C651 Test Method for Flexural Strength of Manufactured
3.1 There is currently a suite of ASTM standards (see 2.1)
Carbon and GraphiteArticles Using Four-Point Loading at
that can be applied to graphite covering a range of physical,
Room Temperature
mechanical, electrical and thermal property measurements.
C695 Test Method for Compressive Strength of Carbon and
Each of these standards has been developed with the objective
Graphite
ofoptimizingthemethodofmeasurementintheabsenceofany
C714 Test Method for Thermal Diffusivity of Carbon and
constraints on test specimen production. Without exception,
Graphite by Thermal Pulse Method
these standards specify limits on the ratio between test speci-
C747 Test Method for Moduli of Elasticity and Fundamen-
mendimensionsandcokeandfillergrainsizesorprescribetest
specimen geometries or size ranges, or both. The default
position for any user should be to follow these standards
1
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum
exactly as described. However, in some applications, available
Products and Lubricants and is the direct responsibility of Subcommittee D02.F0 on
test material or experiment design constraints on test specimen
Manufactured Carbon and Graphite Products.
sizes may result in noncompliance. The objective of this guide
Current edition approved Dec. 1, 2011. Published January 2012. DOI: 10.1520/
D7775–11.
is to provide advice on how the application of selected
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
standards under noncompliant conditions can be tested for
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
suitability.The ultimate objective is to provide guidance on the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. use of each of the ASTM standards listed. The 2011 issue of
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
D7775–11
this guide addresses eight standards: Test Method C559 for largerelativetotheflashsourceasthefrontsurfaceneedstobe
Bulk Density by Physical Measurement of Manufactured heated uniformly. The specimen thickness must be selected
Carbon and GraphiteArticles, Test Method C611 for Electric
...

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ASTM D7775-21(Guide)
Standard Guide for Measurements on Small Graphite Specimens

SIGNIFICANCE AND USE
4.1 The purpose of this guide is to report considerations, which should be included in testing nonstandard specimens that lie outside the constraints imposed on size/volume in existing ASTM standards for graphite (noting that there are some generic ASTM standards with no such constraints). These constraints may be real or may be an artifact of the round-robin test program that supported the standard. It is the responsibility of the user to demonstrate that the application of a standard outside any specified constraints is valid and reasonably provides properties of the bulk material from which the nonstandard specimen was extracted.
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1.1 This guide covers best practice for properties measurements on small (nonstandard) graphite specimens and requirements for representing properties of the bulk material. This guide is aimed specifically at measurements required on graphites, where there may be constraints on the geometry or volume of the test specimen, or both. The objective of this guide is to provide advice on how the application of selected standards under noncompliant conditions can be tested for suitability.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 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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ASTM D8356-20(Test Method)
Standard Test Method for Sonic Velocity in Manufactured Carbons and Graphite Materials for use in Obtaining Approximate Elastic Constants: Young’s Modulus, Shear Modulus, and Poisson’s Ratio

SIGNIFICANCE AND USE
5.1 Sonic velocity measurements are useful for comparing materials with similar elastic properties, dimensions, and microstructure.  
5.2 Eq 1 provides an accurate value of Young’s modulus only for isotropic, non-attenuative, non-dispersive materials of infinite dimensions. For non-isotropic graphite Eq 1 can be modified to take into account the Poisson’s ratios in all directions. As graphite is a strongly attenuative material, the value of Young’s modulus obtained with Eq 1 will be dependent on specimen length. If the specimen lateral dimensions are not large compared with the wavelength of the propagated pulse, then the value of Young’s modulus obtained with Eq 1 will be dependent on the specimen lateral dimensions. The accuracy of the Young’s modulus calculated from Eq 1 will also depend upon uncertainty in Poisson’s ratio and its impact on the evaluation of the Poisson’s factor in Eq 2. However, a value for Young’s modulus Eq 1 or Eq 7) can be obtained for many applications, which is often in good agreement with the value obtained by other more accurate methods, such as in Test Method C747. The technical issues and typical values of corresponding uncertainties are discussed in detail in STP 1578.6  
5.3 If the grain size of the carbon or graphite is greater than or about equal to the wavelength of the sonic pulse, the method may not provide a value of the Young’s modulus representative of the bulk material. Therefore it would be desirable to test a lower frequency (longer wavelength) to demonstrate that the range of obtained velocity values are within acceptable levels of accuracy. Significant signal attenuation should be expected when grain size of the material is greater than or about equal to the wavelength of the transmitted sonic pulse or the material is more porous than would be expected for as-manufactured graphite.
Note 1: Due to frequency dependent attenuation in graphite, the wavelength of the sonic pulse through the test specimen is not necessaril...
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1.1 This test method covers a procedure for measuring the longitudinal and transverse (shear) sonic velocities in manufactured carbon and graphite which can be used to obtain approximate values for the elastic constants: Young’s modulus (E), the shear modulus (G), and Poisson’s ratio (v).  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 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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ASTM D7779-20(Test Method)
Standard Test Method for Determination of Fracture Toughness of Graphite at Ambient Temperature

SIGNIFICANCE AND USE
5.1 This test method may be used for guidance for material development to improve toughness, material comparison, quality assessment, and characterization.  
5.2 The fracture toughness value provides information on the initiation of fracture in graphite containing a straight-through notch; the information on stress intensity factor beyond fracture toughness as a function of crack extension provides information on the crack propagation resistance once a fracture crack has been initiated to propagate through the test specimen.
SCOPE
1.1 This test method covers and provides a measure of the resistance of a graphite to crack extension at ambient temperature and atmosphere expressed in terms of stress-intensity factor, K, and strain energy release rate, G. These crack growth resistance properties are determined using beam test specimens with a straight-through sharp machined V-notch.  
1.2 This test method determines the stress intensity factor, K, from applied force and gross specimen deflection measured away from the crack tip. The stress intensity factor calculated at the maximum applied load is denoted as fracture toughness, KIc, and is known as the critical stress intensity factor. If the resolution of the deflection gauge is sensitive to fracture behavior in the test specimen and can provide a measure of the specimen compliance, strain energy release rate, G, can be determined as a function of crack extension.  
1.3 This test method is applicable to a variety of grades of graphite which exhibit different types of resistance to crack growth, such as growth at constant stress intensity (strain energy release rate), or growth with increasing stress intensity (strain energy release rate), or growth with decreasing stress intensity (strain energy release rate). It is generally recognized that because of the inhomogeneous microstructure of graphite, the general behavior will exhibit a mixture of all three during the test. The crack resistance behavior exhibited in the test is usually referred to as an “R-curve.”  
Note 1: One difference between the procedure in this test method and test methods such as Test Method E399, which measure fracture toughness, KIc, by one set of specific operational procedures, is that Test Method E399 focuses on the start of crack extension from a fatigue precrack for metallic materials. This test method for graphite makes use of a machined notch with sharp cracking at the root of the notch because of the nature of graphite. Therefore, fracture toughness values determined with this method may not be interchanged with KIc as defined in Test Method E399.  
1.4 This test method gives fracture toughness values, KIc and critical strain energy release rate, GIc for specific conditions of environment, deformation rate, and temperature. Fracture toughness values for a graphite grade can be functions of environment, deformation rate, and temperature.  
1.5 This test method is divided into two major parts. The first major part is the main body of the standard, which provides general information on the test method, the applicability to materials comparison and qualification, and requirements and recommendations for fracture toughness testing. The second major part is composed of annexes, which provide information related to test apparatus and test specimen geometry.    
Main Body  
Section  
Scope  
1  
Referenced Documents  
2  
Terminology  
3  
Summary of Test Method  
4  
Significance and Use  
5  
Apparatus  
6  
Test Specimen  
7  
Procedure  
8  
Specimen Dryness  
9  
Calculation of Results  
10  
Report  
11  
Precision and Bias  
12  
Keywords  
13  
Annex  
Annex A1  
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.6.1 Measurement units expressed in these test methods are in accordance with IEEE/ASTM SI 10.  
1.7 This standard does no...

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ASTM D8289-20(Test Method)
Standard Test Method for Tensile Strength Estimate by Disc Compression of Manufactured Graphite

SIGNIFICANCE AND USE
4.1 By definition, the tensile strength of manufactured graphite is obtained by the direct uniaxial tensile test (Test Method C749). The C749 tensile test specimen is relatively large and is frequently incompatible with available irradiation capsule volumes, or oxidation apparatus (Test Method D7542). The splitting tensile test provides an alternate means of testing tensile properties on specimens that have severe geometric constraints and otherwise cannot meet the prescribed testing geometries of Test Method C749. By loading a disc-shaped specimen, on edge, under a compressive load, the resulting tensile stresses transverse to the loading axis provide an indication of the tensile strength properties of graphite. To obtain consistent and meaningful values of a splitting tensile strength, it is vital that the fracture initiate in the center of the disk and not along an edge. This standard test helps to ensure that the disk specimens break diametrally along the loading diameter due to tensile stresses that are perpendicular to the loading axis and that the fracture initiates at the center of the disk.  
4.2 The stress determined using the diametral compression test is the maximum tensile stress at the center of the disk when loaded under the prescribed conditions and the fracture initiates at the center of the disk. It should be understood that this tensile stress value is obtained with the specimen in a complex biaxial stress condition. When the test is performed carefully and consistently these tensile stress values are comparable to each other, but the performers of this test should validate the values obtained. Any bias when comparing values with this standard to the uniaxial tensile stress values obtained using Test Method C749 should be identified and reported. Validation shall be performed on the same material and may not be applicable to other states of the same material (for example, oxidized, irradiated). Guidance on small specimen testing can be found in G...
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1.2 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.  
1.3 All dimension and force measurements and stress calculations shall conform to the guidelines for significant digits and rounding established in Practice D6026.  
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.  
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SIGNIFICANCE AND USE
5.1 The properties determined by these test methods are of value in material specifications, qualifications, data base generation, certification, research, and development.  
5.2 These test methods are intended for the testing of fibers that have been specifically developed for use as reinforcing agents in advanced composite structures. The test results of an impregnated and consolidated fiber should be representative of the strength and modulus that are available in the material when used as intended. The performance of fibers in different resin systems can vary significantly so that correlations between results using these test methods and composite testing may not always be obtained.  
5.3 The reproducibility of test results is dependent upon precise control over all test conditions. Resin type, content and distribution, curing process, filament alignment, gripping in the testing machine, and alignment in the testing machine are of special importance.  
5.4 The measured strengths of fibers are not unique quantities and test results are strongly dependent on the test methods used. Therefore the test method described here will not necessarily give the same mean strengths or standard deviations as those obtained from single filaments, dry fibers, composite laminas, or composite laminates.
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1.2 These test methods also cover the determination of the density and mass per unit length of the yarn, roving, or tow to provide supplementary data for tensile property calculation.  
1.3 These test methods include a procedure for sizing removal to provide the preferred desized fiber samples for density measurement. This procedure may also be used to determine the weight percent sizing.  
1.4 These test methods include a procedure for determining the weight percent moisture adsorption of carbon or graphite fiber.  
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1.6 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.  
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5.1 The test is used to determine the oxidative resistances of carbon fibers as a means of selecting the most stable fibers for incorporation in high-temperature fiber-reinforced composite systems. It can be used for quality control, material specification, and for research and development of improved carbon fibers. Factors that influence the oxidative resistance and should be reported are fiber identification, carbon fiber precursor type, fiber modulus, and any information on impurities, particularly metals. Also note that the presence of finish on the fiber can affect the oxidative resistance, and thus, alternative specimen preparations that enable the evaluation of finish effects are included.
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1.1 This test method covers the apparatus and procedure for the determination of the weight loss of carbon fibers, exposed to ambient hot air, as a means of characterizing their oxidative resistance.  
1.2 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.  
1.2.1 Within the text, the inch-pound units are shown in brackets.  
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ASTM D7775-21(Guide)
Standard Guide for Measurements on Small Graphite Specimens

SIGNIFICANCE AND USE
4.1 The purpose of this guide is to report considerations, which should be included in testing nonstandard specimens that lie outside the constraints imposed on size/volume in existing ASTM standards for graphite (noting that there are some generic ASTM standards with no such constraints). These constraints may be real or may be an artifact of the round-robin test program that supported the standard. It is the responsibility of the user to demonstrate that the application of a standard outside any specified constraints is valid and reasonably provides properties of the bulk material from which the nonstandard specimen was extracted.
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1.1 This guide covers best practice for properties measurements on small (nonstandard) graphite specimens and requirements for representing properties of the bulk material. This guide is aimed specifically at measurements required on graphites, where there may be constraints on the geometry or volume of the test specimen, or both. The objective of this guide is to provide advice on how the application of selected standards under noncompliant conditions can be tested for suitability.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 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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ASTM D8356-20(Test Method)
Standard Test Method for Sonic Velocity in Manufactured Carbons and Graphite Materials for use in Obtaining Approximate Elastic Constants: Young’s Modulus, Shear Modulus, and Poisson’s Ratio

SIGNIFICANCE AND USE
5.1 Sonic velocity measurements are useful for comparing materials with similar elastic properties, dimensions, and microstructure.  
5.2 Eq 1 provides an accurate value of Young’s modulus only for isotropic, non-attenuative, non-dispersive materials of infinite dimensions. For non-isotropic graphite Eq 1 can be modified to take into account the Poisson’s ratios in all directions. As graphite is a strongly attenuative material, the value of Young’s modulus obtained with Eq 1 will be dependent on specimen length. If the specimen lateral dimensions are not large compared with the wavelength of the propagated pulse, then the value of Young’s modulus obtained with Eq 1 will be dependent on the specimen lateral dimensions. The accuracy of the Young’s modulus calculated from Eq 1 will also depend upon uncertainty in Poisson’s ratio and its impact on the evaluation of the Poisson’s factor in Eq 2. However, a value for Young’s modulus Eq 1 or Eq 7) can be obtained for many applications, which is often in good agreement with the value obtained by other more accurate methods, such as in Test Method C747. The technical issues and typical values of corresponding uncertainties are discussed in detail in STP 1578.6  
5.3 If the grain size of the carbon or graphite is greater than or about equal to the wavelength of the sonic pulse, the method may not provide a value of the Young’s modulus representative of the bulk material. Therefore it would be desirable to test a lower frequency (longer wavelength) to demonstrate that the range of obtained velocity values are within acceptable levels of accuracy. Significant signal attenuation should be expected when grain size of the material is greater than or about equal to the wavelength of the transmitted sonic pulse or the material is more porous than would be expected for as-manufactured graphite.
Note 1: Due to frequency dependent attenuation in graphite, the wavelength of the sonic pulse through the test specimen is not necessaril...
SCOPE
1.1 This test method covers a procedure for measuring the longitudinal and transverse (shear) sonic velocities in manufactured carbon and graphite which can be used to obtain approximate values for the elastic constants: Young’s modulus (E), the shear modulus (G), and Poisson’s ratio (v).  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 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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ASTM D7779-20(Test Method)
Standard Test Method for Determination of Fracture Toughness of Graphite at Ambient Temperature

SIGNIFICANCE AND USE
5.1 This test method may be used for guidance for material development to improve toughness, material comparison, quality assessment, and characterization.  
5.2 The fracture toughness value provides information on the initiation of fracture in graphite containing a straight-through notch; the information on stress intensity factor beyond fracture toughness as a function of crack extension provides information on the crack propagation resistance once a fracture crack has been initiated to propagate through the test specimen.
SCOPE
1.1 This test method covers and provides a measure of the resistance of a graphite to crack extension at ambient temperature and atmosphere expressed in terms of stress-intensity factor, K, and strain energy release rate, G. These crack growth resistance properties are determined using beam test specimens with a straight-through sharp machined V-notch.  
1.2 This test method determines the stress intensity factor, K, from applied force and gross specimen deflection measured away from the crack tip. The stress intensity factor calculated at the maximum applied load is denoted as fracture toughness, KIc, and is known as the critical stress intensity factor. If the resolution of the deflection gauge is sensitive to fracture behavior in the test specimen and can provide a measure of the specimen compliance, strain energy release rate, G, can be determined as a function of crack extension.  
1.3 This test method is applicable to a variety of grades of graphite which exhibit different types of resistance to crack growth, such as growth at constant stress intensity (strain energy release rate), or growth with increasing stress intensity (strain energy release rate), or growth with decreasing stress intensity (strain energy release rate). It is generally recognized that because of the inhomogeneous microstructure of graphite, the general behavior will exhibit a mixture of all three during the test. The crack resistance behavior exhibited in the test is usually referred to as an “R-curve.”  
Note 1: One difference between the procedure in this test method and test methods such as Test Method E399, which measure fracture toughness, KIc, by one set of specific operational procedures, is that Test Method E399 focuses on the start of crack extension from a fatigue precrack for metallic materials. This test method for graphite makes use of a machined notch with sharp cracking at the root of the notch because of the nature of graphite. Therefore, fracture toughness values determined with this method may not be interchanged with KIc as defined in Test Method E399.  
1.4 This test method gives fracture toughness values, KIc and critical strain energy release rate, GIc for specific conditions of environment, deformation rate, and temperature. Fracture toughness values for a graphite grade can be functions of environment, deformation rate, and temperature.  
1.5 This test method is divided into two major parts. The first major part is the main body of the standard, which provides general information on the test method, the applicability to materials comparison and qualification, and requirements and recommendations for fracture toughness testing. The second major part is composed of annexes, which provide information related to test apparatus and test specimen geometry.    
Main Body  
Section  
Scope  
1  
Referenced Documents  
2  
Terminology  
3  
Summary of Test Method  
4  
Significance and Use  
5  
Apparatus  
6  
Test Specimen  
7  
Procedure  
8  
Specimen Dryness  
9  
Calculation of Results  
10  
Report  
11  
Precision and Bias  
12  
Keywords  
13  
Annex  
Annex A1  
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.6.1 Measurement units expressed in these test methods are in accordance with IEEE/ASTM SI 10.  
1.7 This standard does no...

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ASTM
ASTM D8289-20(Test Method)
Standard Test Method for Tensile Strength Estimate by Disc Compression of Manufactured Graphite

SIGNIFICANCE AND USE
4.1 By definition, the tensile strength of manufactured graphite is obtained by the direct uniaxial tensile test (Test Method C749). The C749 tensile test specimen is relatively large and is frequently incompatible with available irradiation capsule volumes, or oxidation apparatus (Test Method D7542). The splitting tensile test provides an alternate means of testing tensile properties on specimens that have severe geometric constraints and otherwise cannot meet the prescribed testing geometries of Test Method C749. By loading a disc-shaped specimen, on edge, under a compressive load, the resulting tensile stresses transverse to the loading axis provide an indication of the tensile strength properties of graphite. To obtain consistent and meaningful values of a splitting tensile strength, it is vital that the fracture initiate in the center of the disk and not along an edge. This standard test helps to ensure that the disk specimens break diametrally along the loading diameter due to tensile stresses that are perpendicular to the loading axis and that the fracture initiates at the center of the disk.  
4.2 The stress determined using the diametral compression test is the maximum tensile stress at the center of the disk when loaded under the prescribed conditions and the fracture initiates at the center of the disk. It should be understood that this tensile stress value is obtained with the specimen in a complex biaxial stress condition. When the test is performed carefully and consistently these tensile stress values are comparable to each other, but the performers of this test should validate the values obtained. Any bias when comparing values with this standard to the uniaxial tensile stress values obtained using Test Method C749 should be identified and reported. Validation shall be performed on the same material and may not be applicable to other states of the same material (for example, oxidized, irradiated). Guidance on small specimen testing can be found in G...
SCOPE
1.1 This test method covers testing apparatus, specimen preparation, and testing procedures for determining the splitting tensile strength of graphite by diametral line compression of a disk. This small specimen geometry (Test Method D7779) is specifically intended for irradiation capsule use. Users are cautioned to use Test Method C749 if possible for measuring tensile strength properties of graphite.  
1.2 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.  
1.3 All dimension and force measurements and stress calculations shall conform to the guidelines for significant digits and rounding established in Practice D6026.  
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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