ASTM D4018 - 23

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Designation: D4018 −23
Standard Test Methods for
Properties of Continuous Filament Carbon and Graphite
Fiber Tows
1
This standard is issued under the ﬁxed designation D4018; 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
1.1 These test methods cover the preparation and tensile
testing of resin-impregnated and consolidated test specimens
made from continuous ﬁlament carbon and graphite yarns,
rovings, and tows to determine their tensile properties.
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.
1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
standard.
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 appro-
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
2
D70 Test Method for Speciﬁc Gravity and Density of Semi-
Solid Asphalt Binder (Pycnometer Method)
D1193 Speciﬁcation for Reagent Water
D3800 Test Method for Density of High-Modulus Fibers
D5550 Test Method for Speciﬁc Gravity of Soil Solids by
Gas Pycnometer
E4 Practices for Force Calibration and Veriﬁcation of Test-
ing Machines
E83 Practice for Veriﬁcation and Classiﬁcation of Exten-
someter Systems
2.2 Other Document:
CRC Handbook of Chemistry and Physics
3
3. Terminology
3.1 Deﬁnitions:
3.1.1 sizing, n—a generic term for compounds which, when
applied to yarn or fabric, form a more or less continuous solid
ﬁlm around the yarn and individual ﬁbers.
3.2 Deﬁnitions of Terms Speciﬁc to This Standard:
3.2.1 desized ﬁber, n—ﬁber which has had a sizing removed
from it.
3.2.2 ﬁber, n—continuous ﬁlament carbon or graphite yarn,
roving, or tow.
3.2.3 sized ﬁber, n—a ﬁber with a sizing applied to it.
3.2.4 unsized ﬁber, n—ﬁber which has never had a sizing
applied to it.
3.3 Symbols:
3.3.1 A—Unit conversion factor for tensile strength
1
These test methods are under the jurisdiction of ASTM Committee D30 on
Composite Materials and are the direct responsibility of Subcommittee D30.03 on
Constituent/Precursor Properties.
Current edition approved Sept. 1, 2023. Published September 2023. Originally
approved in 1981. Last previous edition approved in 2017 as D4018 – 17. DOI:
10.1520/D4018-23.
2
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.
3
CRC Press Inc., Boca Raton, Ann Arbor, London, Tokyo, 73rd Edition,
1992–1993.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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.
1

3.3.2 B—Unit conversion factor for tensile modulus

3.3.3 E—ﬁber chord modulus

3.3.4 ε

—Lower strain limit

3.3.5 ε

—Upper strain limit

3.3.6 k

—correction factor for density of sizing

3.3.7 L—specimen length

3.3.8 MUL—the mass per unit length of the sized ﬁber

3.3.9 MUL

—the mass per unit length of the impregnated

and consolidated ﬁber

3.3.10 P—maximum load

3.3.11 P

—tensile load at lower strain limit

3.3.12 P

—tensile load at upper strain limit

3.3.13 ρ

—density of the ﬁber

3.3.14 ρ

—density of the ﬁber with sizing

3.3.15 RC—weight percent of resin (resin content)

3.3.16 W

—specimen mass

4. Summary of Test Methods

4.1 These test methods include procedures for determining

the tensile strength and modulus of a resin-impregnated and

consolidated carbon ﬁber tow. Also included are procedures to

measure the mass per unit length and density of the carbon

ﬁber and the resin content of the resin-impregnated and

consolidated specimens.

4.2 MUL—The MUL of the ﬁber is determined by dividing

the mass of a sample of sized ﬁber by its length.

4.3 Density—The density of the ﬁber is determined using

Archimedes’ method or a pycnometer method. The recom-

mended specimen is desized or unsized ﬁber. The ideal

immersion ﬂuid is one that completely wets the specimen and

provides minimum toxicity or environmental hazard.

4.4 Resin Content—The resin content (weight percent) of

the resin-impregnated and consolidated ﬁber is determined by

comparing the mass per unit length of the impregnated and

consolidated specimen to the ﬁber mass per unit length.

4.5 Tensile Properties—The tensile strength and tensile

chord modulus of the ﬁber are determined by the tensile

loading to failure of the resin-impregnated and consolidated

ﬁber. The chord modulus is determined between deﬁned strain

limits. The purpose of the impregnating resin is to provide the

ﬁber, when consolidated, with sufficient mechanical strength to

produce an easily handled test specimen capable of sustaining

uniform loading of the individual ﬁlaments in the specimen.

The resin shall be compatible with the ﬁber and any sizing

applied to it. The strain capability of the consolidated resin

shall be at least twice the strain capability of the ﬁber.

5. 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 be-

tween 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 quan-

tities 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 devia-

tions as those obtained from single ﬁlaments, dry ﬁbers,

composite laminas, or composite laminates.

6. Apparatus

6.1 Three sets of apparatus are required. One set is for resin

impregnation of the ﬁber. A second set is for curing the

resin-impregnated specimens. A third set is for tensile testing

the resin-impregnated and consolidated specimens. Optional

apparatus may be used for applying end tabs to the specimens

and removing sizing.

6.1.1 Resin Impregnation—The goal of the resin-

impregnation apparatus is to apply and uniformly impregnate

resin into the ﬁber. This is normally achieved by dipping the

ﬁber into the resin and then working the wet ﬁber over rolls or

through a die, or both. While automated apparatuses are

preferred for consistency, any apparatus which achieves uni-

form impregnation of 35 % to 60 % resin by weight and does

not damage the ﬁber is acceptable.

6.1.2 Consolidation—An apparatus to hold the impregnated

specimens under tension during consolidation is required.

6.1.3 Optional End Tabs—An apparatus to cast resin end

tabs on specimens may be used. Apparatuses to apply and align

other forms of end tabs such as bonded on cardboard or metal

tabs may also be used.

6.1.4 Testing—A tensile testing machine and recorder meet-

ing the requirements of Practices E4 at the maximum expected

test load are required. The load recording device shall be

coordinated with the extensometer and strain recorder to assure

that the corresponding load and elongation of the specimen are

recorded at essentially the same time. The testing machine

shall also have the following features:

6.1.4.1 Grips—Grips suitable for loading the tabbed or

untabbed specimen without damaging it are required. For resin

tabbed specimens a custom grip is generally required. For

untabbed or cardboard tabbed specimens pneumatic or hydrau-

lically powered grips are typically used. Different grip pressure

settings may be required for different ﬁbers.

6.1.4.2 Jaws—Jaws compatible with the grips and capable

of holding a specimen without damaging it are required. For

untabbed specimens, ﬂat jaws with rubber or other compliant

materials bonded to the face are generally used. Sandpaper

may also be placed on the grips to reduce slippage. For

D4018 − 23

cardboard tabbed specimens serrated jaws are generally used.
Jaws should be inspected regularly and cleaned or repaired as
required.
6.1.4.3 Extensometer and Recorder—An extensometer and
recording device in accordance with the requirements of
Practice E83 Class B-2 are required. The extensometer and
recorder shall be coordinated with the tensile testing machine
so that the corresponding load and elongation of the specimen
are recorded at essentially the same time.
6.1.4.4 Balance, Analytical—Accuracy of 60.0002 g for
mass per unit length, density, and resin or sizing content
determinations.
6.1.4.5 Balance, Laboratory—Accuracy of 60.1 g for
measuring components of resin.
6.1.4.6 Length Measuring Devices—Devices to measure the
length of impregnated and consolidated specimens and dry
ﬁber to 62 mm accuracy are required.
6.1.4.7 Density Measuring Device—See Test Methods D70,
D3800, or D5550.
6.1.4.8 Forced Air Oven—A forced air oven of sufficient
sizing and temperature capabilities to cure the impregnated
ﬁber on the curing device. The temperature shall be controlled
to 610 °C.
7. Reagents and Materials
7.1 Reagent Water—Unless otherwise indicated, references
to water shall be understood to mean reagent water as deﬁned
by Type III of Speciﬁcation D1193.
7.2 Resin.
7.3 Commercial Grade Solvent, (optional) for resin dilution.
7.4 Hardener or Catalyst.
7.5 Surfactant (optional).
8. Test Specimens
8.1 Mass per Unit Length Specimen—The specimen to
measure mass per unit length is an 1 m minimum length of
ﬁber in the form in which it is intended to be used. Test one
specimen per sample. Coil the specimen into a usable form for
testing. Care is required to not damage and lose ﬁlaments from
the specimen.
8.2 Density Specimen—Density specimens may be sized,
unsized, or desized material. Unsized or desized samples are
preferred. Test one specimen per sample. An 1 m minimum
length is required for Test Method D3800. For methods in Test
Methods D70 and D5550, a suitable volume to ﬁll the
container is recommended. Coil the specimen into a usable
form for testing. Care is required to not damage and lose
ﬁlaments from the specimen.
8.3 Tensile Test Specimen—The tensile specimen shall be a
tabbed or untabbed resin-impregnated and consolidated ﬁber.
Tabbed specimens shall have a 150 mm 65 mm gauge length
between the tabs. Untabbed specimens shall be of sufficient
length to allow a 150 mm 65 mm gauge length between the
grips when they are tested. Samples with 3000 ﬁlaments or less
may be tested using specimens of more than one ﬁber bundle
to facilitate handling. Combine the bundles before resin im-
pregnation and count the test results as one specimen. Test a
minimum of four test specimens per sample. Separate test
specimens for modulus and strength determination are permit-
ted; however, four specimens for each test are required.
Specimens that are fuzzy, curved, not uniform in cross section,
have broken ﬁlaments, resin lumps, or other observable defects
should be rejected unless they are representative of the material
being tested.
9. Conditioning
9.1 Fibers that adsorb less than 0.5 % moisture by weight at
23°C 62 °C and 90 % or greater relative humidity require no
conditioning before testing. Conduct mass per unit length,
density, and tensile testing for these materials at 23 °C 67 °C
and 50 % 620 % relative humidity unless other conditions are
the variables of interest.
9.2 Fibers that adsorb more than 0.5 % moisture by weight
at 23 °C 62 °C and 90 % or greater relative humidity require
conditioning before testing. Condition ﬁbers at 23 °C 62 °C
and 50 % 610 % relative humidity for a minimum of 24 h.
Conduct mass per unit length and density testing at 23 °C 6
2 °C and 50 % 610 % relative humidity unless other condi-
tions are the variables of interest. Conduct tensile testing at
23 °C 67 °C and 50 % 610 % relative humidity unless other
conditions are the variables of interest.
9.3 To determine moisture adsorption, dry a minimum of
ﬁve mass per unit-type specimens at 120 °C 65 °C for 24 h in
a circulating air oven. Cool the specimens in a desiccator.
Remove the specimens from desiccator one at a time and
immediately weigh them. Place the specimens in a humidity
chamber and maintain at 23 °C 62 °C and 90 % or greater
relative humidity for 24 h. Remove the specimens from the
humidity chamber one at a time and weigh immediately.
9.4 If all specimens are conditioned for 24 h and mass per
unit length and density testing are performed at 23 °C 62 °C
and 50 % 610 % relative humidity, then no testing for
moisture adsorption is required.
9.5 Moisture adsorption testing is only required once annu-
ally for a standard product.
10. Specimen Preparation
10.1 Mass per Unit Length—No preparation is required. The
sample is taken from a package of material as it is intended to
be used.
10.2 Density—The preferred density specimen is a desized
or unsized ﬁber. This eliminates any need to correct for the
density of the sizing. The sizing may be removed using solvent
extraction, pyrolysis, or other means. An example method is
described in Appendix X1. An unsized sample of a sized ﬁber
would have to be collected during the production of the ﬁber
and is therefore not recommended.
10.3 Tensile Test—The tensile test specimen must be im-
pregnated with resin and consolidated before testing.
10.3.1 Resin Preparation—Any resin that meets the require-
ments of 4.5 may be used. The resin when combined with the
ﬁber shall produce a composite (reinforcement/matrix) failure.
D4018 − 23
3

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摘要：

ASTM D4018 - 23 是 ASTM 国际标准组织发布的最新版本标准，全称为《Standard Test Methods for Tensile Properties of Continuous Filament Carbon and Graphite Yarns, Strands, Rovings, and Tows》。该标准规定了测定连续碳纤维和石墨纤维纱线、丝束、粗纱及纤维束的拉伸性能的试验方法，包括试样制备、测试条件、加载速率及数据处理要求。适用于航空航天、复合材料、汽车、风电叶

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