ASTM D7775-11(2015)

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.
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: 31-May-2015
• ICS: 59.100.20 - Carbon materials
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.F0 - Manufactured Carbon and Graphite Products

Relations

• Replaces: ASTM D7775-11e1 - Standard Guide for Measurements on Small Graphite Specimens
• Effective Date: 01-Jun-2015
• Referred By: ASTM D8289-20 - Standard Test Method for Tensile Strength Estimate by Disc Compression of Manufactured Graphite
• Effective Date: 01-Jun-2015
• 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-Jun-2015
• Referred By: ASTM D7846-21 - Standard Practice for Reporting Uniaxial Strength Data and Estimating Weibull Distribution Parameters for Advanced Graphites
• Effective Date: 01-Jun-2015
• Referred By: ASTM D8091-21 - Standard Guide for Impregnation of Graphite with Molten Salt
• Effective Date: 01-Jun-2015
• Referred By: ASTM C781-20 - Standard Practice for Testing Graphite Materials for Gas-Cooled Nuclear Reactor Components
• Effective Date: 01-Jun-2015
• Referred By: ASTM D8255-19 - Standard Guide for Work of Fracture Measurements on Small Nuclear Graphite Specimens
• Effective Date: 01-Jun-2015
• Referred By: ASTM C695-21 - Standard Test Method for Compressive Strength of Carbon and Graphite
• Effective Date: 01-Jun-2015
• 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-Jun-2015
• Referred By: ASTM C714-17 - Standard Test Method for Thermal Diffusivity of Carbon and Graphite by Thermal Pulse Method
• Effective Date: 01-Jun-2015

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: D7775 − 11 (Reapproved 2015) An American National Standard
Standard Guide for
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 C748 Test Method for Rockwell Hardness of Graphite Ma-
terials
1.1 This guide covers best practice for properties measure-
C749 Test Method for Tensile Stress-Strain of Carbon and
ments on small (nonstandard) graphite specimens and require-
Graphite
ments for representing properties of the bulk material. This
C769 Test Method for Sonic Velocity in Manufactured
guide is aimed specifically at measurements required on
Carbon and Graphite Materials for Use in Obtaining
nuclear graphites, where there may be constraints on the
Young’s Modulus
geometry or volume of the test specimen, or both.
C781 Practice for Testing Graphite and Boronated Graphite
1.2 The values stated in SI units are to be regarded as
Materials for High-Temperature Gas-Cooled Nuclear Re-
standard. No other units of measurement are included in this
actor Components
standard.
C886 Test Method for Scleroscope Hardness Testing of
1.3 This standard does not purport to address all of the Carbon and Graphite Materials
safety concerns, if any, associated with its use. It is the
C1161 Test Method for Flexural Strength of Advanced
responsibility of the user of this standard to establish appro- Ceramics at Ambient Temperature
priate safety and health practices and determine the applica-
C1259 Test Method for Dynamic Young’s Modulus, Shear
bility of regulatory limitations prior to use. Modulus, and Poisson’s Ratio for Advanced Ceramics by
Impulse Excitation of Vibration
2. Referenced Documents
E228 Test Method for Linear Thermal Expansion of Solid
2.1 ASTM Standards: Materials With a Push-Rod Dilatometer
C559 Test Method for Bulk Density by Physical Measure- E1461 Test Method for Thermal Diffusivity by the Flash
ments of Manufactured Carbon and Graphite Articles Method
C565 Test Methods for Tension Testing of Carbon and
Graphite Mechanical Materials
3. Summary of Guide
C611 TestMethodforElectricalResistivityofManufactured
3.1 There is currently a suite of ASTM standards (see 2.1)
Carbon and Graphite Articles at Room Temperature
that can be applied to graphite covering a range of physical,
C651 Test Method for Flexural Strength of Manufactured
mechanical, electrical and thermal property measurements.
CarbonandGraphiteArticlesUsingFour-PointLoadingat
Each of these standards has been developed with the objective
Room Temperature
ofoptimizingthemethodofmeasurementintheabsenceofany
C695 Test Method for Compressive Strength of Carbon and
constraints on test specimen production. Without exception,
Graphite
these standards specify limits on the ratio between test speci-
C714 Test Method for Thermal Diffusivity of Carbon and
men dimensions and coke and filler grain sizes or prescribe test
Graphite by Thermal Pulse Method
specimen geometries or size ranges, or both. The default
C747 Test Method for Moduli of Elasticity and Fundamental
position for any user should be to follow these standards
Frequencies of Carbon and Graphite Materials by Sonic
exactly as described. However, in some applications, available
Resonance
test material or experiment design constraints on test specimen
sizes may result in noncompliance. The objective of this guide
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum
is to provide advice on how the application of selected
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
standards under noncompliant conditions can be tested for
mittee D02.F0 on Manufactured Carbon and Graphite Products.
suitability.The ultimate objective is to provide guidance on the
CurrenteditionapprovedJune1,2015.PublishedJuly2015.Originallyapproved
ε1
use of each of the ASTM standards listed. The 2011 issue of
in 2011. Last previous edition approved in 2011 as D7775 – 11 . DOI: 10.1520/
D7775-11R15.
this guide addresses eight standards: Test Method C559 for
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Bulk Density by Physical Measurement of Manufactured
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Carbon and GraphiteArticles, Test Method C611 for Electrical
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. Resistivity of Manufactured Carbon and Graphite Articles at
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7775 − 11 (2015)
RoomTemperature,TestMethodC747forModuliofElasticity large relative to the flash source as the front surface needs to be
and Fundamental Frequencies of Carbon and Graphite Mate- heated uniformly. The specimen thickness must be selected
rials by Sonic Resonance, Test Method C769 for Sonic such that τ/t is smaller than 0.02, where τ is the pulse time
1/2
Velocity in Manufactured Carbon and Graphite Materials for and t is the time for the rear surface temperature to rise to
1/2
Use in Obtaining Young’s Modulus, Test Method C749 for one half of its maximum value.
Tensile Stress-Strain of Carbon and Graphite and Practice
5.7 Test Method C747—Applies to slender rod or bar
C781 for Testing Graphite and Boronated Graphite Materials
geometries. The test specimen length to thickness ratio should
for High-Temperature Gas-Cooled Nuclear Reactor
lie in the range 5 to 20:1.
Components,Test Method E228 for LinearThermal Expansion
5.8 Test Method C748—Applies to flat specimens of mini-
of Solid Materials with a Push-Rod Dilatometer, and Test
mum thickness 6.35 mm. The grain size of the test material
Method E1461 for Thermal Diffusivity by the Flash Method.
should be less than 0.8 mm, with a hardness range 0 to 120
4. Significance and Use
Rockwell L.
4.1 The purpose of this guide is to report considerations,
5.9 Test Method C749—Applies to reduced-diameter uni-
which should be included in testing nonstandard specimens
axial tensile test geometries as defined in Fig. 9 of that
that lie outside the constraints imposed on size/volume in
standard. Gage diameter must be greater than 3 to 5 times the
existing ASTM standards for graphite (noting that there are
maximum grain size.
some generic ASTM standards with no such constraints).
5.10 Test Method C769—Applies to right cylinder geom-
These constraints may be real or may be an artifact of the
etry. The user should minimize attenuation of the sonic pulse
round-robin test program that supported the standard. It is the
by selecting a wavelength appropriate to the grain size of the
responsibility of the user to demonstrate that the application of
test material. If the test specimen is a few grains thick,
a standard outside any specified constraints is valid and
acceptability of application should be tested over a range of
reasonably provides properties of the bulk material from which
lengths. Specimen should have a diameter of at least a factor of
the nonstandard specimen was extracted.
two and ideally a factor of five greater than the wavelength of
5. Test Specimen Volume/Size Constraints in Current
sound within the material.
Standards
5.11 Test Method C886—Can be applied to any convenient
5.1 Test Method C559—Applies to test specimens with
test specimen size, but test surfaces smaller than 5 mm by
rectangular parallelepiped or right circular cylinder geometry.
5 mm are not recommended. The material must have a grain
The minimum test volume is specified as 500 mm . The
size less than 0.8 mm. The minimum specimen thickness is
minimum test specimen dimension should be 10 times the
5 mm.
length of the largest visible grain.
5.12 Test Method E228—Applies to right cylinder (prefer-
5.2 Test Methods C565—Applies to reduced diameter uni-
able) or slab geometries. Ideally, test specimens should be
axial tensile specimens. Grain size must be smaller than
25 mm to 60 mm long and 5 mm to 10 mm in diameter or
0.79 mm; while not specified, it is assumed that this refers to
equivalent (although there is no fundamental limitation pro-
average grain size. The acceptable fracture zone shall be
vided the instrument controls the maximum thermal gradient to
19 mm long with the centre of the zone at the point of
better than 62 °C⁄50 mm). The specimen length should be
minimum diameter. The ratio of specimen diameter to grain
such that the accuracy of determining the expansion ∆L/L is
size or flaw size must be greater than 5.
at least 620 mm⁄m.
5.3 Test Method C611—Applies to strip, rod, bar or tube
5.13 Test Method E1461—Applies to thin circular disk
geometries. Specimen length to maximum cross-sectional di-
specimens with the front surface area less than that of the
mension should be 6:1. No dimension should be smaller than 5
energy beam. Typically, test specimens should be 10 mm to
times the length of the largest visible grain.
12.5 mm in diameter and 1 mm to 6 mm in thickness.
5.4 Test Method C651—Applies to rectangular parallelepi-
5.14 Test Method C1259—Can be applied to graphite test
ped geometries. The minimum dimension should be greater
specimens with both round and rectangular cross sections. The
than 5 times the largest grain dimension. Test specimen length
ratio of test specimen length to minimal cross-sectional dimen-
tothicknessshouldbegreaterthan8.Theratiooftestspecimen
sion should be greater than 10, and preferably greater than 20.
width to thickness should be less than or equal to 2.
For shear modulus measurements, the test specimen width to
5.5 Test Method C695—Applies to right cylinder geometry. thickness ratio should be greater than 5.
The test specimen diameter should be greater than 10 times the
5.15 Test Method C1161—Applies to rectangular parallel-
maximum grain size. The test specimen height to diameter
epiped geometries and can be adapted for graphite. The
ratio should be in the range 1.9 to 2.1. The minimum test size
average grain size should be less than 2 % of the beam
is specified as 9.5 mm diameter and 19.1 mm height.
thickness. For beam lengths of 25 mm, 45 mm, and 90 mm,
5.6 TestMethodC714—Applies to circular disks, 2 to 4 mm specified widths are 2 mm, 4 mm, and 8 mm, respectively, and
thickand6to12mmindiameter.Thediametermustnotbetoo specified depths are 1.5 mm, 3 mm, and 6 mm, respectively.
D7775 − 11 (2015)
6. General Principle for Measurements Outside Specified either a rectangular parallelepiped or right cylinder geometry.
Specimen Volume/Size Constraints in Current The standard specifies that the specimen volume should not be
Standards
less than 500 mm and the minimum dimension must be at
least ten times the length of the largest visible grain. The
6.1 The default position for any user should be to follow
minimum dimension should also be more than 2000 times the
these standards exactly as described.
resolution of the measuring device. The volume determination
6.2 Specimen size and volume constraints may be set by a
involves four length measurements (longest dimension) either
particular measurement technique and hence apply to any test
at the centre of each long face in the case of the rectangular
material, but some may depend upon the microstructure and
parallelepiped or 90° apart on the periphery of the circular end
composition of the material. In such cases, it is preferable to
faces in the case of the right cylinder. For the rectangular
provide technical data and basis to support the choice of the
parallelepiped, width and thickness at each end and at two
adapted measurement technique and test specimen dimensions
intermediate points along the length are required. For the right
used.
cylinder, two sets of diameter measurements are required, each
6.3 A simple, general principle should be applied to any
set consisting of four measurements, one at each end and two
proposed measurements that are noncompliant with respect to at two intermediate points along an axial line.
volume/size.
7.2 The accuracy of contact measuring devices must be
6.3.1 The user must first specify the level of accuracy
assessed in the context of point and flat contact options.
required for the measurements together with tolerable
repeatability, tolerance, and bias uncertainties associated with
7.3 Principal sources of mensuration error will arise from
themeasuredproperties.Thismayneedtotakeintoaccountthe
geometry irregularity and from surface condition.
number of specimens used for the measurements.
7.4 For specimens of regular geometry, mensuration could
6.3.2 These qualifying measurement criteria must be dem-
be carried out with automated multi-measurement contact
onstrated using representative material in a manner compliant
devices that record and analyze results for prescribed measure-
with the ASTM standard. The user should take account of
ment patterns.
in-service changes to test material (for example, irradiation,
oxidation) when selecting representative material for such a
7.5 Non-contact scanning devices can also be used to
demonstration; as-manufactured material may not be suffi-
determine volumes of both regular and non-regular geometry
ciently representative for such purposes.
specimens. Such devices need careful qualification before use
6.3.3 The measurements should then be repeated on the
to ensure the detectors respond consistently for graphite
same material, progressively reducing the volume/size of the
surfaces. The calibration and accuracy of the device must be
specimen and repeating the measurements. Ideally, this proce-
tested on volume standards made from materials that respond
dure would involve the successive re-sizing of the starting
to the scanning beam in a simple manner to graphite.
specimen. This would ensure that no specimen to specimen
7.6 Bulk density can also be determined usingArchimedes’
variability affected the results. Consideration should be given
Principle, as an alternative to mensuration techniques. The
to within specimen variability and any potential effects of
specimen immersed in a fluid is subject to an upwards
specimen preparation that might affect the property measure-
buoyancyforceequaltotheweightofthefluiddisplacedbythe
ment. This process should be continued until there are suffi-
specimen. By measuring the weight of the immersed specimen,
cient compliant data to benchmark the measurement technique
the buoyancy force can be deduced, and by using the measured
against the material; there should be sufficient d
...

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: D7775 − 11 D7775 − 11 (Reapproved 2015) An American National Standard
Standard Guide for
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.
ε NOTE—Minor formatting changes made throughout editorially in July 2012.
1. 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.
2. Referenced Documents
2.1 ASTM Standards:
C559 Test Method for Bulk Density by Physical Measurements of Manufactured Carbon and Graphite Articles
C565 Test Methods for Tension Testing of Carbon and Graphite Mechanical Materials
C611 Test Method for Electrical Resistivity of Manufactured Carbon and Graphite Articles at Room Temperature
C651 Test Method for Flexural Strength of Manufactured Carbon and Graphite Articles Using Four-Point Loading at Room
Temperature
C695 Test Method for Compressive Strength of Carbon and Graphite
C714 Test Method for Thermal Diffusivity of Carbon and Graphite by Thermal Pulse Method
C747 Test Method for Moduli of Elasticity and Fundamental Frequencies of Carbon and Graphite Materials by Sonic Resonance
C748 Test Method for Rockwell Hardness of Graphite Materials
C749 Test Method for Tensile Stress-Strain of Carbon and Graphite
C769 Test Method for Sonic Velocity in Manufactured Carbon and Graphite Materials for Use in Obtaining Young’s Modulus
C781 Practice for Testing Graphite and Boronated Graphite Materials for High-Temperature Gas-Cooled Nuclear Reactor
Components
C886 Test Method for Scleroscope Hardness Testing of Carbon and Graphite Materials
C1161 Test Method for Flexural Strength of Advanced Ceramics at Ambient Temperature
C1259 Test Method for Dynamic Young’s Modulus, Shear Modulus, and Poisson’s Ratio for Advanced Ceramics by Impulse
Excitation of Vibration
E228 Test Method for Linear Thermal Expansion of Solid Materials With a Push-Rod Dilatometer
E1461 Test Method for Thermal Diffusivity by the Flash Method
3. Summary of Guide
3.1 There is currently a suite of ASTM standards (see 2.1) that can be applied to graphite covering a range of physical,
mechanical, electrical and thermal property measurements. Each of these standards has been developed with the objective of
optimizing the method of measurement in the absence of any constraints on test specimen production. Without exception, these
standards specify limits on the ratio between test specimen dimensions and coke and filler grain sizes or prescribe test specimen
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.F0 on Manufactured Carbon and Graphite Products.
Current edition approved Dec. 1, 2011June 1, 2015. Published January 2012July 2015. Originally approved in 2011. Last previous edition approved in 2011 as
ε1
D7775 – 11 . DOI: 10.1520/D7775–11.10.1520/D7775-11R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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
D7775 − 11 (2015)
geometries or size ranges, or both. The default position for any user should be to follow these standards exactly as described.
However, in some applications, available test material or experiment design constraints on test specimen sizes may result in
noncompliance. The objective of this guide is to provide advice on how the application of selected standards under noncompliant
conditions can be tested for suitability. The ultimate objective is to provide guidance on the use of each of the ASTM standards
listed. The 2011 issue of this guide addresses eight standards: Test Method C559 for Bulk Density by Physical Measurement of
Manufactured Carbon and Graphite Articles, Test Method C611 for Electrical Resistivity of Manufactured Carbon and Graphite
Articles at Room Temperature, Test Method C747 for Moduli of Elasticity and Fundamental Frequencies of Carbon and Graphite
Materials by Sonic Resonance, Test Method C769 for Sonic Velocity in Manufactured Carbon and Graphite Materials for Use in
Obtaining Young’s Modulus, Test Method C749 for Tensile Stress-Strain of Carbon and Graphite and Practice C781 for Testing
Graphite and Boronated Graphite Materials for High-Temperature Gas-Cooled Nuclear Reactor Components, Test Method E228
for Linear Thermal Expansion of Solid Materials with a Push-Rod Dilatometer, and Test Method E1461 for Thermal Diffusivity
by the Flash Method.
4. 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.
5. Test Specimen Volume/Size Constraints in Current Standards
5.1 Test Method C559—Applies to test specimens with rectangular parallelepiped or right circular cylinder geometry. The
minimum test volume is specified as 500 mm500 mm . The minimum test specimen dimension should be 10 times the length of
the largest visible grain.
5.2 Test Methods C565—Applies to reduced diameter uniaxial tensile specimens. Grain size must be smaller than 0.79 mm;
0.79 mm; while not specified, it is assumed that this refers to average grain size. The acceptable fracture zone shall be 19 mm
19 mm long with the centre of the zone at the point of minimum diameter. The ratio of specimen diameter to grain size or flaw
size must be greater than 5.
5.3 Test Method C611—Applies to strip, rod, bar or tube geometries. Specimen length to maximum cross-sectional dimension
should be 6:1. No dimension should be smaller than 5 times the length of the largest visible grain.
5.4 Test Method C651—Applies to rectangular parallelepiped geometries. The minimum dimension should be greater than 5
times the largest grain dimension. Test specimen length to thickness should be greater than 8. The ratio of test specimen width to
thickness should be less than or equal to 2.
5.5 Test Method C695—Applies to right cylinder geometry. The test specimen diameter should be greater than 10 times the
maximum grain size. The test specimen height to diameter ratio should be in the range 1.9 to 2.1. The minimum test size is
specified as 9.5 mm 9.5 mm diameter and 19.1 mm 19.1 mm height.
5.6 Test Method C714—Applies to circular disks, 2 to 4 mm thick and 6 to 12 mm in diameter. The diameter must not be too
large relative to the flash source as the front surface needs to be heated uniformly. The specimen thickness must be selected such
that τ/t is smaller than 0.02, where τ is the pulse time and t is the time for the rear surface temperature to rise to one half of
1/2 1/2
its maximum value.
5.7 Test Method C747—Applies to slender rod or bar geometries. The test specimen length to thickness ratio should lie in the
range 5 to 20:1.
5.8 Test Method C748—Applies to flat specimens of minimum thickness 6.35 mm. 6.35 mm. The grain size of the test material
should be less than 0.8 mm, 0.8 mm, with a hardness range 0 to 120 Rockwell L.
5.9 Test Method C749—Applies to reduced-diameter uniaxial tensile test geometries as defined in Fig. 9 of that standard. Gage
diameter must be greater than 3 to 5 times the maximum grain size.
5.10 Test Method C769—Applies to right cylinder geometry. The user should minimize attenuation of the sonic pulse by
selecting a wavelength appropriate to the grain size of the test material. If the test specimen is a few grains thick, acceptability of
application should be tested over a range of lengths. Specimen should have a diameter of at least a factor of two and ideally a factor
of five greater than the wavelength of sound within the material.
5.11 Test Method C886—Can be applied to any convenient test specimen size, but test surfaces smaller than 55 mm by 5 mm
5 mm are not recommended. The material must have a grain size less than 0.8 mm. 0.8 mm. The minimum specimen thickness
is 5 mm.5 mm.
5.12 Test Method E228—Applies to right cylinder (preferable) or slab geometries. Ideally, test specimens should be 2525 mm
to 60 mm 60 mm long and 55 mm to 10 mm 10 mm in diameter or equivalent (although there is no fundamental limitation provided
D7775 − 11 (2015)
the instrument controls the maximum thermal gradient to better than 62°C/5062 °C ⁄ mm). 50 mm). The specimen length should
be such that the accuracy of determining the expansion ΔL/L is at least 620 620 mm mm/m.⁄m.
5.13 Test Method E1461—Applies to thin circular disk specimens with the front surface area less than that of the energy beam.
Typically, test specimens should be 1010 mm to 12.5 mm 12.5 mm in diameter and 11 mm to 6 mm 6 mm in thickness.
5.14 Test Method C1259—Can be applied to graphite test specimens with both round and rectangular cross sections. The ratio
of test specimen length to minimal cross-sectional dimension should be greater than 10, and preferably greater than 20. For shear
modulus measurements, the test specimen width to thickness ratio should be greater than 5.
5.15 Test Method C1161—Applies to rectangular parallelepiped geometries and can be adapted for graphite. The average grain
size should be less than 2%2 % of the beam thickness. For beam lengths of 25, 45, and 90 mm, 25 mm, 45 mm, and 90 mm,
specified widths are 2, 4, and 8 mm, 2 mm, 4 mm, and 8 mm, respectively, and specified depths are 1.5, 3, and 6 mm, 1.5 mm,
3 mm, and 6 mm, respectively.
6. General Principle for Measurements Outside Specified Specimen Volume/Size Constraints in Current Standards
6.1 The default position for any user should be to follow these standards exactly as described.
6.2 Specimen size and volume constraints may be set by a particular measurement technique and hence apply to any test
material, but some may depend upon the microstructure and composition of the material. In such cases, it is preferable to provide
technical data and basis to support the choice of the adapted measurement technique and test specimen dimensions used.
6.3 A simple, general principle should be applied to any proposed measurements that are noncompliant with respect to
volume/size.
6.3.1 The user must first specify the level of accuracy required for the measurements together with tolerable repeatability,
tolerance, and bias uncertainties associated with the measured properties. This may need to take into account the number of
specimens used for the measurements.
6.3.2 These qualifying measurement criteria must be demonstrated using representative material in a manner compliant with the
ASTM standard. The user should take account of in-service changes to test material (for example, irradiation, oxidation) when
selecting representative material for such a demonstration; as-manufactured material may not be sufficiently representative for such
purposes.
6.3.3 The measurements should then be repeated on the same material, progressively reducing the volume/size of the specimen
and repeating the measurements. Ideally, this procedure would involve the successive re-sizing of the starting specimen. This
would ensure that no specimen to specimen variability affected the results. Consideration should be given to within specimen
variability and any potential effects of specimen preparation that might affect the property measurement. This process should be
continued until there are sufficient compliant data to benchmark the measurement technique against the material; there should be
sufficient data at and below the desired test specimen geometry to characterize the dependence of the measured property upon
volume/size. It may be necessary to study more than one parameter and these should be varied singly in order not to confound the
results.
6.3.4 The results should be analyzed to establish either the standard can be applied directly to an extended specimen volume/size
range or it can be applied with volume/size corrections. In both cases, the accuracy and uncertainty of the measurement at the
desired specimen volume/size should be evaluated and assessed for acceptability against the original specification.
6.3.5 It is good practice to retain the test specimens as checks or secondary standards in the subsequent measurement campaigns.
7. Bulk Density by Physical Measurement (Test Method C559)
7.1 Test Method C559 requires a mass measurement and a volume determination by mensuration on a test specimen with either
a rectangular parallelepiped or right cylinder geometry. The standard specifies that the specimen volume should not be less than
500 mm500 mm and the minimum dimension must be at least ten times the length of the largest visible grain. The minimum
dimension should also be more than 2000 times the resolution of the measuring device. The volume determination involves four
length measurements (longest dimension) either at the centre of each long face in the case of the rectangular parallelepiped or 90°
...