ASTM D638-22

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D638 − 22
Standard Test Method for
Tensile Properties of Plastics
This standard is issued under the fixed designation D638; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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* consider the precautions and limitations of this method found
in Note 2 and Section 4 before considering these data for
1.1 This test method covers the determination of the tensile
engineering design.
properties of unreinforced and reinforced plastics in the form
1.5 The values stated in SI units are to be regarded as
ofstandarddumbbell-shapedtestspecimenswhentestedunder
standard. The values given in parentheses are for information
defined conditions of pretreatment, temperature, humidity, and
only.
testing machine speed.
1.6 This standard does not purport to address all of the
1.2 This test method is applicable for testing materials of
safety concerns, if any, associated with its use. It is the
any thickness up to 14 mm (0.55 in.). However, for testing
responsibility of the user of this standard to establish appro-
specimensintheformofthinsheeting,includingfilmlessthan
priate safety, health, and environmental practices and deter-
1.0 mm (0.04 in.) in thickness, ASTM standard D882 is the
mine the applicability of regulatory limitations prior to use.
preferred test method. Materials with a thickness greater than
1.7 This international standard was developed in accor-
14 mm (0.55 in.) shall be reduced by machining.
dance with internationally recognized principles on standard-
1.3 This test method includes the option of determining
ization established in the Decision on Principles for the
Poisson’s ratio at room temperature.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
NOTE 1—This standard and ISO 527-1 address the same subject matter,
but differ in technical content.
Barriers to Trade (TBT) Committee.
NOTE 2—This test method is not intended to cover precise physical
procedures. It is recognized that the constant rate of crosshead movement
2. Referenced Documents
type of test leaves much to be desired from a theoretical standpoint, that
2.1 ASTM Standards:
wide differences may exist between rate of crosshead movement and rate
of strain between gage marks on the specimen, and that the testing speeds D229Test Methods for Rigid Sheet and Plate Materials
specified disguise important effects characteristic of materials in the
Used for Electrical Insulation
plastic state. Further, it is realized that variations in the thicknesses of test
D412TestMethodsforVulcanizedRubberandThermoplas-
specimens,whicharepermittedbytheseprocedures,producevariationsin
tic Elastomers—Tension
thesurface-volumeratiosofsuchspecimens,andthatthesevariationsmay
D618Practice for Conditioning Plastics for Testing
influence the test results. Hence, where directly comparable results are
desired, all samples should be of equal thickness. Special additional tests
D651Test Method for Test for Tensile Strength of Molded
should be used where more precise physical data are needed.
Electrical Insulating Materials (Withdrawn 1989)
NOTE 3—This test method may be used for testing phenolic molded
D882Test Method for Tensile Properties of Thin Plastic
resin or laminated materials. However, where these materials are used as
Sheeting
electrical insulation, such materials should be tested in accordance with
D883Terminology Relating to Plastics
Test Methods D229 and Test Method D651.
NOTE 4—For tensile properties of resin-matrix composites reinforced D1822Test Method for Determining the Tensile-Impact
with oriented continuous or discontinuous high modulus >20-GPa
Resistance of Plastics
(>3.0×10 -psi) fibers, tests shall be made in accordance with Test
D3039/D3039MTest Method forTensile Properties of Poly-
Method D3039/D3039M.
mer Matrix Composite Materials
1.4 Test data obtained by this test method have been found
D4000Classification System for Specifying Plastic Materi-
to be useful in engineering design. However, it is important to
als
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction ofASTM Committee D20 on Plastics contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties. Standards volume information, refer to the standard’s Document Summary page on
CurrenteditionapprovedJuly1,2022.PublishedJuly2022.Originallyapproved the ASTM website.
in 1941. Last previous edition approved in 2014 as D638-14. DOI: 10.1520/ The last approved version of this historical standard is referenced on
D0638-22. www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D638 − 22
D4066Classification System for Nylon Injection and Extru- the limit of usefulness can be made for most plastics. This
sion Materials (PA) sensitivity to rate of straining and environment necessitates
D5947Test Methods for Physical Dimensions of Solid testing over a broad load-time scale (including impact and
Plastics Specimens creep) and range of environmental conditions if tensile prop-
E4Practices for Force Calibration and Verification of Test- erties are to suffice for engineering design purposes.
ing Machines
NOTE 5—Since the existence of a true elastic limit in plastics (as in
E83Practice for Verification and Classification of Exten-
many other organic materials and in many metals) is debatable, the
someter Systems
propriety of applying the term “elastic modulus” in its quoted, generally
E132Test Method for Poisson’s Ratio at RoomTemperature
accepted definition to describe the “stiffness” or “rigidity” of a plastic has
beenseriouslyquestioned.Theexactstress-straincharacteristicsofplastic
E456Terminology Relating to Quality and Statistics
materials are highly dependent on such factors as rate of application of
E691Practice for Conducting an Interlaboratory Study to
stress, temperature, previous history of specimen, etc. However, stress-
Determine the Precision of a Test Method
strain curves for plastics, determined as described in this test method,
E2935Practice for Evaluating Equivalence of Two Testing
almost always show a linear region at low stresses, and a straight line
Processes drawn tangent to this portion of the curve permits calculation of an elastic
modulus of the usually defined type. Such a constant is useful if its
2.2 ISO Standard:
arbitrary nature and dependence on time, temperature, and similar factors
ISO 527-1Determination of Tensile Properties
are realized.
3. Terminology
5. Apparatus
3.1 Terms used in this standard are defined in accordance
5.1 Testing Machine—A testing machine of the constant-
with Terminology D883, and Annex A2. For terms relating to
rate-of-crosshead-movement type and comprising essentially
precision and bias and associated issues, the terms used in this
the following:
standard are defined in accordance with Terminology E456.
5.1.1 Fixed Member—A fixed or essentially stationary
4. Significance and Use
member carrying one grip.
4.1 This test method is designed to produce tensile property 5.1.2 Movable Member—A movable member carrying a
dataforthecontrolandspecificationofplasticmaterials.These
second grip.
data are also useful for qualitative characterization and for
5.1.3 Grips—Grips for holding the test specimen between
research and development.
the fixed member and the movable member of the testing
machine can be either the fixed or self-aligning type.
4.2 Some material specifications that require the use of this
test method, but with some procedural modifications that take 5.1.3.1 Fixed grips are rigidly attached to the fixed and
precedence when adhering to the specification. Therefore, it is movable members of the testing machine. When this type of
advisabletorefertothatmaterialspecificationbeforeusingthis grip is used take extreme care to ensure that the test specimen
test method. Table 1 in Classification D4000 lists the ASTM is inserted and clamped so that the long axis of the test
materials standards that currently exist. specimen coincides with the direction of pull through the
center line of the grip assembly.
4.3 Tensile properties are known to vary with specimen
5.1.3.2 Self-aligning grips are attached to the fixed and
preparation and with speed and environment of testing.
movablemembersofthetestingmachineinsuchamannerthat
Consequently, where precise comparative results are desired,
they will move freely into alignment as soon as any load is
these factors must be carefully controlled.
applied so that the long axis of the test specimen will coincide
4.4 Itisrealizedthatamaterialcannotbetestedwithoutalso
with the direction of the applied pull through the center line of
testingthemethodofpreparationofthatmaterial.Hence,when
the grip assembly.Align the specimens as perfectly as possible
comparativetestsofmaterialspersearedesired,exercisegreat
with the direction of pull so that no rotary motion that may
caretoensurethatallsamplesarepreparedinexactlythesame
induce slippage will occur in the grips; there is a limit to the
way, unless the test is to include the effects of sample
amountofmisalignmentself-aligninggripswillaccommodate.
preparation. Similarly, for referee purposes or comparisons
5.1.3.3 The test specimen shall be held in such a way that
within any given series of specimens, care shall be taken to
slippage relative to the grips is prevented insofar as possible.
secure the maximum degree of uniformity in details of
Grip surfaces that are deeply scored or serrated with a pattern
preparation, treatment, and handling.
similar to those of a coarse single-cut file, serrations about 2.4
4.5 Tensile properties provide useful data for plastics engi-
mm (0.09 in.) apart and about 1.6 mm (0.06 in.) deep, have
neering design purposes. However, because of the high degree
been found satisfactory for most thermoplastics. Finer serra-
ofsensitivityexhibitedbymanyplasticstorateofstrainingand
tions have been found to be more satisfactory for harder
environmental conditions, data obtained by this test method
plastics,suchasthethermosettingmaterials.Itisimportantthat
cannotbeconsideredvalidforapplicationsinvolvingload-time
the serrations be kept clean and sharp. Should breaking in the
scales or environments widely different from those of this test
grips occur, even when deep serrations or abraded specimen
method.Incasesofsuchdissimilarity,noreliableestimationof
surfaces are used, other techniques shall be used. Other
techniques that have been found useful, particularly with
smooth-faced grips, are abrading that portion of the surface of
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. the specimen that will be in the grips, and interposing thin
D638 − 22
pieces of abrasive cloth, abrasive paper, or plastic, or rubber- classification within the range of use for modulus measure-
coated fabric, commonly called hospital sheeting, between the ments meets this requirement.
specimen and the grip surface. No. 80 double-sided abrasive 5.2.2 Low-Extension Measurements—For elongation-at-
paper has been found effective in many cases. An open-mesh yield and low-extension measurements (nominally 20% or
fabric, in which the threads are coated with abrasive, has also less), the same above extensometer, attenuated to 20 %
been effective. Reducing the cross-sectional area of the speci- extension, is acceptable. In any case, the extensometer system
men may also be effective. The use of special types of grips is must meet at least Class C (Practice E83) requirements, which
sometimes necessary to eliminate slippage and breakage in the include a fixed strain error of 0.001 strain or 61.0% of the
grips. indicated strain, whichever is greater.
5.2.3 High-Extension Measurements—Formakingmeasure-
5.1.4 Drive Mechanism—A drive mechanism for imparting
ments at elongations greater than 20%, measuring techniques
a uniform, controlled velocity to the movable member with
with error no greater than 610% of the measured value are
respect to the stationary member. This velocity is to be
acceptable.
regulated as specified in Section 8.
5.1.5 Load Indicator—A suitable load-indicating mecha-
5.3 Micrometers—Apparatus for measuring the width and
nism capable of showing the total tensile load carried by the
thickness of the test specimen shall comply with the require-
testspecimenwhenheldbythegrips.Thismechanismshallbe
ments of Test Method D5947.
essentially free of inertia lag at the specified rate of testing and
shall indicate the load with an accuracy of 61% of the
6. Test Specimens
indicated value, or better. The accuracy of the testing machine
6.1 Sheet, Plate, and Molded Plastics:
shall be verified in accordance with Practices E4.
6.1.1 Rigid and Semirigid Plastics—The test specimen shall
NOTE 6—Experience has shown that many testing machines now in use conform to the dimensions shown in Fig. 1. The Type I
are incapable of maintaining accuracy for as long as the periods between
specimen is the preferred specimen and shall be used where
inspection recommended in Practices E4. Hence, it is recommended that
sufficientmaterialhavingathicknessof7mm(0.28in.)orless
each machine be studied individually and verified as often as may be
is available. The Type II specimen is recommended when a
found necessary. It frequently will be necessary to perform this function
materialdoesnotbreakinthenarrowsectionwiththepreferred
daily.
Type I specimen. The Type V specimen shall be used where
5.1.6 The fixed member, movable member, drive
only limited material having a thickness of 4 mm (0.16 in.) or
mechanism, and grips shall be constructed of such materials
less is available for evaluation, or where a large number of
and in such proportions that the total elastic longitudinal strain
specimens are to be exposed in a limited space (thermal and
ofthesystemconstitutedbythesepartsdoesnotexceed1%of
environmental stability tests, etc.). The Type IV specimen is
thetotallongitudinalstrainbetweenthetwogagemarksonthe
generally used when direct comparisons are required between
test specimen at any time during the test and at any load up to
materials in different rigidity cases (that is, nonrigid and
the rated capacity of the machine.
semirigid). The Type III specimen must be used for all
5.1.7 Crosshead Extension Indicator—A suitable extension
materials with a thickness of greater than 7 mm (0.28 in.) but
indicating mechanism capable of showing the amount of
not more than 14 mm (0.55 in.).
change in the separation of the grips, that is, crosshead
6.1.2 Nonrigid Plastics—The test specimen shall conform
movement.This mechanism shall be essentially free of inertial
tothedimensionsshowninFig.1.TheTypeIVspecimenshall
lag at the specified rate of testing and shall indicate the
be used for testing nonrigid plastics with a thickness of 4 mm
crosshead movement with an accuracy of 610% of the
(0.16 in.) or less. The Type III specimen must be used for all
indicated value.
materials with a thickness greater than 7 mm (0.28 in.) but not
5.2 Extension Indicator (extensometer)—A suitable instru- more than 14 mm (0.55 in.).
ment shall be used for determining the distance between two
6.1.3 Reinforced Composites—The test specimen for rein-
designated points within the gauge length of the test specimen forced composites, including highly orthotropic laminates,
as the specimen is stretched. For referee purposes, the exten-
shall conform to the dimensions of theType I specimen shown
someter must be set at the full gage length of the specimen, as in Fig. 1.
shown in Fig. 1. It is desirable, but not essential, that this
6.1.4 Preparation—Methods of preparing test specimens
instrument automatically record this distance, or any change in include injection molding, machining operations, or die
it, as a function of the load on the test specimen or of the
cutting, from materials in sheet, plate, slab, or similar form.
elapsedtimefromthestartofthetest,orboth.Ifonlythelatter Materialsthickerthan14mm(0.55in.)shallbemachinedto14
is obtained, load-time data must also be taken.This instrument
mm (0.55 in.) for use as Type III specimens.
shall be essentially free of inertia at the specified speed of
NOTE 7—Test results have shown that for some materials such as glass
testing. Extensometers shall be classified, and their calibration
cloth, SMC, and BMC laminates, other specimen types should be
periodically verified in accordance with Practice E83.
considered to ensure breakage within the gage length of the specimen, as
mandated by 7.3.
5.2.1 Modulus-of-Elasticity Measurements—For modulus-
NOTE 8—When preparing specimens from certain composite laminates
of-elasticity measurements, an extensometer with a maximum
such as woven roving, or glass cloth, exercise care in cutting the
strain error of 0.0002 mm/mm (in./in.) that automatically and
specimens parallel to the reinforcement. The reinforcement will be
continuously records shall be used.An extensometer classified
significantly weakened by cutting on a bias, resulting in lower laminate
by Practice E83 as fulfilling the requirements of a B-2 properties, unless testing of specimens in a direction other than parallel
D638 − 22
A
Specimen Dimensions for Thickness, T, mm (in.)
7 (0.28) or under Over 7 to 14 (0.28 to 0.55), incl 4 (0.16) or under
Dimensions (see drawings) Tolerances
B C,D
Type I Type II Type III Type IV Type V
E,F B,C
W—Width of narrow section 13 (0.50) 6 (0.25) 19 (0.75) 6 (0.25) 3.18 (0.125) ±0.5 (±0.02)
C
L—Length of narrow section 57 (2.25) 57 (2.25) 57 (2.25) 33 (1.30) 9.53 (0.375) ±0.5 (±0.02)
G
WO—Width overall, min 19 (0.75) 19 (0.75) 29 (1.13) 19 (0.75) . + 6.4 ( + 0.25)
G
WO—Width overall, min . . . . 9.53 (0.375) + 3.18 ( + 0.125)
H
LO—Length overall, min 165 (6.5) 183 (7.2) 246 (9.7) 115 (4.5) 63.5 (2.5) no max (no max)
I C
G—Gage length 50 (2.00) 50 (2.00) 50 (2.00) . 7.62 (0.300) ±0.25 (±0.010)
I
G—Gage length . . . 25 (1.00) . ±0.13 (±0.005)
J
D—Distance between grips 115 (4.5) 135 (5.3) 115 (4.5) 65 (2.5) 25.4 (1.0) ±5 (±0.2)
C
R—Radius of fillet 76 (3.00) 76 (3.00) 76 (3.00) 14 (0.56) 12.7 (0.5) ±1 (±0.04)
RO—Outer radius (Type IV) . . . 25 (1.00) . ±1 (±0.04)
A
Thickness, T, shall be 3.2± 0.4 mm (0.13 ± 0.02 in.) for all types of molded specimens, and for other Types I and II specimens where possible. If specimens are machined
from sheets or plates, thickness, T, shall be the thickness of the sheet or plate provided this does not exceed the range stated for the intended specimen type. For sheets
of nominal thickness greater than 14 mm (0.55 in.) the specimens shall be machined to 14 ± 0.4 mm (0.55 ± 0.02 in.) in thickness, for use with the Type III specimen. For
sheets of nominal thickness between 14 and 51 mm (0.55 and 2 in.) approximately equal amounts shall be machined from each surface. For thicker sheets both surfaces
of the specimen shall be machined, and the location of the specimen with reference to the original thickness of the sheet shall be noted. Tolerances on thickness less than
14 mm (0.55 in.) shall be those standard for the grade of material tested.
B
For the Type IV specimen, the internal width of the narrow section of the die shall be 6.00 ± 0.05 mm (0.250 ± 0.002 in.). The dimensions are essentially those of Die
C in Test Methods D412.
C
The Type V specimen shall be machined or die cut to the dimensions shown, or molded in a mold whose cavity has these dimensions. The dimensions shall be:
W=3.18±0.03mm(0.125±0.001 in.),
L=9.53±0.08mm(0.375±0.003 in.),
G=7.62±0.02mm(0.300±0.001 in.), and
R=12.7±0.08mm(0.500±0.003 in.).
The other tolerances are those in the table.
D
Supporting data on the introduction of the L specimen of Test Method D1822 as the Type V specimen are available from ASTM Headquarters. Request RR:D20-1038.
E
The tolerances of the width at the center W shall be +0.00 mm, −0.10 mm ( +0.000 in., −0.004 in.) compared with width W at other parts of the reduced section. Any
c
reduction in W at the center shall be gradual, equally on each side so that no abrupt changes in dimension result.
F
For molded specimens, a draft of not over 0.13 mm (0.005 in.) is allowed for either Type I or II specimens 3.2 mm (0.13 in.) in thickness. See diagram below and this
shall be taken into account when calculating width of the specimen. Thus a typical section of a molded Type I specimen, having the maximum allowable draft, could be
as follows:
G
Overall widths greater than the minimum indicated are used for some materials in order to avoid breaking in the grips.
H
Overall lengths greater than the minimum indicated are used for some materials to avoid breaking in the grips or to satisfy special test requirements.
I
Test marks or initial extensometer span.
J
When self-tightening grips are used, for highly extensible polymers, the distance between grips will depend upon the types of grips used and may not be critical if
maintained uniform once chosen.
FIG. 1 Tension Test Specimens for Sheet, Plate, and Molded Plastics
D638 − 22
NOTE 9—Specimens prepared by injection molding may have different
tensile properties than specimens prepared by machining or die-cutting
because of the orientation induced. This effect may be more pronounced
in specimens with narrow sections.
6.2 Rigid Tubes—The test specimen for rigid tubes shall be
asshowninFig.2.Thelength, L,shallbeasshowninthetable
inFig.2.Agrooveshallbemachinedaroundtheoutsideofthe
specimenatthecenterofitslengthsothatthewallsectionafter
machining shall be 60% of the original nominal wall thick-
ness. This groove shall consist of a straight section 57.2 mm
(2.25 in.) in length with a radius of 76 mm (3 in.) at each end
joining it to the outside diameter. Steel or brass plugs having
diameters such that they will fit snugly inside the tube and
having a length equal to the full jaw length plus 25 mm (1 in.)
shall be placed in the ends of the specimens to prevent
crushing. They can be located conveniently in the tube by
separating and supporting them on a threaded metal rod.
Details of plugs and test assembly are shown in Fig. 2.
6.3 Rigid Rods—Thetestspecimenforrigidrodsshallbeas
shown in Fig. 3. The length, L, shall be as shown in the table
in Fig. 3. A groove shall be machined around the specimen at
the center of its length so that the diameter of the machined
portion shall be 60% of the original nominal diameter. This
groove shall consist of a straight section 57.2 mm (2.25 in.) in
length with a radius of 76 mm (3 in.) at each end joining it to
the outside diameter.
6.4 All surfaces of the specimen shall be free of visible
flaws, scratches, or imperfections. Marks left by coarse ma-
chiningoperationsshallbecarefullyremovedwithafinefileor
abrasive, and the filed surfaces shall then be smoothed with
abrasive paper (No. 00 or finer). The finishing sanding strokes
shall be made in a direction parallel to the long axis of the test
specimen.All flash shall be removed from a molded specimen,
taking great care not to disturb the molded surfaces. In
machining a specimen, undercuts that would exceed the
dimensional tolerances shown in Fig. 1 shall be scrupulously
DIMENSIONS OF TUBE SPECIMENS
avoided. Care shall also be taken to avoid other common
Standard Length, L,
Length of Radial Total Calculated
machining errors.
Nominal Wall of Specimen to Be
Sections, Minimum
Thickness Used for 89-mm
6.5 If it is necessary to place gage marks on the specimen,
2R.S. Length of Specimen
A
(3.5-in.) Jaws
this shall be done with a wax crayon or India ink that will not
mm (in.)
affect the material being tested. Gage marks shall not be
0.79 ( ⁄32) 13.9 (0.547) 350 (13.80) 381 (15)
3 scratched, punched, or impressed on the specimen.
1.2 ( ⁄64) 17.0 (0.670) 354 (13.92) 381 (15)
1.6 ( ⁄16) 19.6 (0.773) 356 (14.02) 381 (15)
6.6 When testing materials that are suspected of anisotropy,
2.4 ( ⁄32) 24.0 (0.946) 361 (14.20) 381 (15)
3.2 ( ⁄8) 27.7 (1.091) 364 (14.34) 381 (15) duplicate sets of test specimens shall be prepared, having their
4.8 ( ⁄16) 33.9 (1.333) 370 (14.58) 381 (15)
long axes respectively parallel with, and normal to, the
6.4 ( ⁄4) 39.0 (1.536) 376 (14.79) 400 (15.75)
suspected direction of anisotropy.
7.9 ( ⁄16) 43.5 (1.714) 380 (14.96) 400 (15.75)
9.5 ( ⁄8) 47.6 (1.873) 384 (15.12) 400 (15.75)
11.1 ( ⁄16 ) 51.3 (2.019) 388 (15.27) 400 (15.75) 7. Number of Test Specimens
12.7 ( ⁄2 ) 54.7 (2.154) 391 (15.40) 419 (16.5)
7.1 Test at least five specimens for each sample in the case
A of isotropic materials.
For jaws greater than 89 mm (3.5 in.), the standard length shall be increased by
twice the length of the jaws minus 178 mm (7 in.). The standard length permits a
7.2 For anisotropic materials, when applicable, test five
slippage of approximately 6.4 to 12.7 mm (0.25 to 0.50 in.) in each jaw while
specimens, normal to, and five parallel with, the principal axis
maintaining the maximum length of the jaw grip.
of anisotropy.
FIG. 2 Diagram Showing Location of Tube Tension Test Speci-
7.3 Discardspecimensthatbreakatsomeflaw,orthatbreak
mens in Testing Machine
outside of the narrow cross-sectional test section (Fig. 1,
dimension “L”), and make retests, unless such flaws constitute
with the reinforcement constitutes a variable being studied. a variable to be studied.
D638 − 22
8. Speed of Testing
8.1 Speed of testing shall be the relative rate of motion of
the grips or test fixtures during the test. The rate of motion of
the driven grip or fixture when the testing machine is running
idle may be used, if it can be shown that the resulting speed of
testing is within the limits of variation allowed.
8.2 Choose the speed of testing from Table 1. Determine
thischosenspeedoftestingbythespecificationforthematerial
being tested, or by agreement between those concerned. When
the speed is not specified, use the lowest speed shown in Table
1 for the specimen geometry being used, which gives rupture
within 0.5 to 5-min testing time.
8.3 Make modulus determinations at the speed selected for
the other tensile properties when the recorder response and
resolution are adequate.
9. Conditioning
9.1 Conditioning—Condition the test specimens in accor-
dance with Procedure A of Practice D618, unless otherwise
specified by contract or the relevantASTM material specifica-
tion. Conditioning time is specified as a minimum. Tempera-
ture and humidity tolerances shall be in accordance with
Section 7 of Practice D618 unless specified differently by
contract or material specification.
9.2 Test Conditions—Conductthetestsatthesametempera-
ture and humidity used for conditioning with tolerances in
accordance with Section 7 of Practice D618, unless otherwise
specified by contract or the relevantASTM material specifica-
tion.
DIMENSIONS OF ROD SPECIMENS
10. Procedure
Standard Length, L,of
Total Calculated
Nominal Diam- Length of Radial Specimen to Be Used
10.1 Measure the width and thickness of each specimen to
Minimum
eter Sections, 2R.S. for 89-mm (3.5-in.)
Length of Specimen
A
the nearest 0.025 mm (0.001 in.) using the applicable test
Jaws
methods in D5947.
mm (in.)
3.2 ( ⁄8) 19.6 (0.773) 356 (14.02) 381 (15)
A
TABLE 1 Designations for Speed of Testing
4.7 ( ⁄16) 24.0 (0.946) 361 (14.20) 381 (15)
Nominal
6.4 ( ⁄4) 27.7 (1.091) 364 (14.34) 381 (15)
C
Strain Rate at
9.5 ( ⁄8) 33.9 (1.333) 370 (14.58) 381 (15)
Speed of Testing,
B
Classification Specimen Type
1 Start of Test,
12.7 ( ⁄2 ) 39.0 (1.536) 376 (14.79) 400 (15.75)
mm/min (in./min)
mm/mm· min
15.9 ( ⁄8 ) 43.5 (1.714) 380 (14.96) 400 (15.75)
(in./in.·min)
19.0 ( ⁄4 ) 47.6 (1.873) 384 (15.12) 400 (15.75)
Rigid and Semirigid I, II, III rods and 5 (0.2) ± 25 % 0.1
22.2 ( ⁄8 ) 51.5 (2.019) 388 (15.27) 400 (15.75)
tubes
25.4 (1) 54.7 (2.154) 391 (15.40) 419 (16.5)
1 50 (2) ± 10 % 1
31.8 (1 ⁄4 ) 60.9 (2.398) 398 (15.65) 419 (16.5)
500 (20) ± 10 % 10
38.1 (1 ⁄2 ) 66.4 (2.615) 403 (15.87) 419 (16.5)
3 IV 5 (0.2) ± 25 % 0.15
42.5 (1 ⁄4 ) 71.4 (2.812) 408 (16.06) 419 (16.5)
50 (2) ± 10 % 1.5
50.8 (2) 76.0 (2.993) 412 (16.24) 432 (17)
500 (20) ± 10 % 15
V 1 (0.05) ± 25 % 0.1
A
For jaws greater than 89 mm (3.5 in.), the standard length shall be increased by
10 (0.5) ± 25 % 1
twice the length of the jaws minus 178 mm (7 in.). The standard length permits a
100 (5)± 25 % 10
slippage of approximately 6.4 to 12.7 mm (0.25 to 0.50 in.) in each jaw while
Nonrigid III 50 (2) ± 10 % 1
maintaining the maximum length of the jaw grip.
500 (20) ± 10 % 10
IV 50 (2) ± 10 % 1.5
FIG. 3 Diagram Showing Location of Rod Tension Test Specimen
500 (20) ± 10 % 15
in Testing Machine
A
Select the lowest speed that produces rupture in 0.5 to 5 min for the specimen
geometry being used (see 8.2).
B
See Terminology D883 for definitions.
C
The initial rate of straining cannot be calculated exactly for dumbbell-shaped
NOTE10—Beforetesting,alltransparentspecimensshouldbeinspected
specimens because of extension, both in the reduced section outside the gage
in a polariscope. Those which show atypical or concentrated strain
length and in the fillets. This initial strain rate can be measured from the initial slope
patterns should be rejected, unless the effects of these residual strains
of the tensile strain-versus-time diagram.
constitute a variable to be studied.
D638 − 22
10.1.1 Measure the width and thickness of flat specimens at 11.2 Tensile Strength—Calculate the tensile strength by
thecenterofeachspecimenandwithin5mmofeachendofthe dividing the maximum load sustained by the specimen in
gage length. newtons (pounds-force) by the average original cross-sectional
10.1.2 For injection molded specimens, the actual measure- area in the gage length segment of the specimen in square
mentofonlyonespecimenfromeachsamplewillsufficewhen
metres (square inches). Express the result in pascals (pounds-
it has previously been demonstrated that the specimen-to- force per square inch) and report it to three significant figures
specimen variation in width and thickness is less than 1%.
as tensile strength at yield or tensile strength at break,
10.1.3 For thin sheeting, including film less than 1.0 mm whichever term is applicable. When a nominal yield or break
(0.04 in.), take the width of specimens produced by a Type IV
load less than the maximum is present and applicable, it is
die as the distance between the cutting edges of the die in the often desirable to also calculate, in a similar manner, the
narrow section. For all other specimens, measure the actual
corresponding tensile stress at yield or tensile stress at break
width of the center portion of the specimen to be tested, unless
and report it to three significant figures (see Note A2.8).
it can be shown that the actual width of the specimen is the
11.3 Elongation values are valid and are reported in cases
same as that of the die within the specimen dimension
where uniformity of deformation within the specimen gage
tolerances given in Fig. 1.
length is present. Elongation values are quantitatively relevant
10.1.4 Measure the diameter of rod specimens, and the
and appropriate for engineering design. When non-uniform
inside and outside diameters of tube specimens, to the nearest
deformation(suchasnecking)occurswithinthespecimengage
0.025 mm (0.001 in.) at a minimum of two points 90° apart;
length nominal strain values are reported. Nominal strain
make these measurements along the groove for specimens so
values are of qualitative utility only.
constructed. Use plugs in testing tube specimens, as shown in
11.3.1 Percent Elongation—Percent elongation is the
Fig. 2.
change in gage length relative to the original specimen gage
10.2 Place the specimen in the grips of the testing machine,
length, expressed as a percent. Percent elongation is calculated
taking care to align the long axis of the specimen and the grips
using the apparatus described in 5.2.
with an imaginary line joining the points of attachment of the
11.3.1.1 Percent Elongation at Yield—Calculate the percent
grips to the machine. The distance between the ends of the
elongation at yield by reading the extension (change in gage
gripping surfaces, when using flat specimens, shall be as
length) at the yield point. Divide that extension by the original
indicatedinFig.1.Ontubeandrodspecimens,thelocationfor
gage length and multiply by 100.
the grips shall be as shown in Fig. 2 and Fig. 3. Tighten the
grips evenly and firmly to the degree necessary to prevent 11.3.1.2 Percent Elongation at Break—Calculate the per-
slippage of the specimen during the test, but not to the point cent elongation at break by reading the extension (change in
where the specimen would be crushed. gage length) at the point of specimen rupture. Divide that
extension by the original gage length and multiply by 100.
10.3 Attach the extension indicator.When modulus is being
11.3.2 Nominal Strain—Nominalstrainisthechangeingrip
determined, a Class B-2 or better extensometer is required (see
separation relative to the original grip separation expressed as
5.2.1).
a percent. Nominal strain is calculated using the apparatus
NOTE 11—Modulus of materials is determined from the slope of the
described in 5.1.7.
linear portion of the stress-strain curve. For most plastics, this linear
portion is very small, occurs very rapidly, and must be recorded automati-
11.3.2.1 Nominal strain at break—Calculate the nominal
cally. The change in jaw separation is never to be used for calculating
strain at break by reading the extension (change in grip
modulus or elongation.
separation)atthepointofrupture.Dividethatextensionbythe
10.4 Setthespeedoftestingattheproperrateasrequiredin
original grip separation and multiply by 100.
Section 8, and start the machine.
11.4 Modulus of Elasticity—Calculate the modulus of elas-
10.5 Record the load-extension curve of the specimen.
ticity by extending the initial linear portion of the load-
10.6 Recordtheloadandextensionattheyieldpoint(ifone
extension curve and dividing the difference in stress corre-
exists) and the load and extension at the moment of rupture.
sponding to any segment of section on this straight line by the
corresponding difference in strain. All elastic modulus values
NOTE 12—If it is desired to measure both modulus and failure
properties (yield or break, or both), it may be necessary, in the case of
shall be computed using the average original cross-sectional
highly extensible materials, to run two independent tests. The high
area in the gage length segment of the specimen in the
magnification extensometer normally used to determine properties up to
calculations. The result shall be expressed in pascals (pounds-
the yield point may not be suitable for tests involving high extensibility.
force per square inch) and reported to three significant figures.
If allowed to remain attached to the specimen, the extensometer could be
permanently damaged. A broad-range incremental extensometer or hand-
11.5 Secant Modulus—At a designated strain, this shall be
rule technique may be needed when such materials are taken to rupture.
calculated by dividing the corresponding stress (nominal) by
11. Calculation
thedesignatedstrain.Elasticmodulusvaluesarepreferableand
11.1 Toe compensation shall be made in accordance with shall be calculated whenever possible. However, for materials
Annex A1, unless it can be shown that the toe region of the where no proportionality is evident, the secant value shall be
curve is not due to the take-up of slack, seating of the calculated.DrawthetangentasdirectedinA1.3andFig.A1.2,
specimen, or other artifact, but rather is an authentic material and mark off the designated strain from the yield point where
response. the tangent line goes through zero stress. The stress to be used
D638 − 22
in the calculation is then determined by dividing the load- 13. Precision and Bias
extension curve by the original average cross-sectional area of
13.1 Precision—The precision of this test method is based
the specimen.
on two interlaboratory studies of ASTM D638, Standard Test
11.6 For each series of tests, calculate the arithmetic mean Method for Tensile Properties of Plastics, conducted in 1984
of all values obtained and report it as the “average value” for and 1988, respectively. Tables 2-4 are based on eight labora-
the particular property in question. tories who tested five different materials using Type I speci-
mens of a nominal 3.175 mm (0.125 in.) thickness. Every “test
11.7 Calculate the standard deviation (estimated) as follows
result” represents five individual determinations. Each labora-
and report it to two significant figures:
tory was asked to submit two replicate test results, from a
2 ¯ 2
single operator, for each material. Practice E691 was followed
=
s 5 ~ X 2 nX !/~n 2 1! (1)
(
for the design and analysis of the data; the details are given in
where:
ASTM Research Report No. D20-1125.
s = estimated standard deviation,
13.1.1 Tables 5-8 are based on ten laboratories who tested
X = value of single observation,
eight different materials. For each material, all samples were
n = number of observations, and
molded at one source, but the individual specimens were
¯
X = arithmetic mean of the set of observations.
preparedatthelaboratoriesthattestedthem.Every“testresult”
11.8 See Annex A1 for information on toe compensation. represents five individual determinations. Each laboratory was
asked to submit three test results, from a single operator for
11.9 SeeAnnexA3forthedeterminationofPoisson’sRatio.
each material. Data from some laboratories could not be used
for various reasons, and this is noted in each table. Practice
12. Report
E691 was followed for the design and analysis of the data; the
12.1 Report the following information:
details are given in ASTM Research Report No. D20-1170.
12.1.1 Completeidentificationofthematerialtested,includ-
13.1.2 Tables 9 and 10 are based on eight laboratories who
ingtype,source,manufacturer’scodenumbers,form,principal
tested three different materials. For each material, all samples
dimensions, previous history, etc.,
were molded at one source, but the individual specimens were
12.1.2 Method of preparing test specimens,
preparedatthelaboratoriesthattestedthem.Every“testresult”
12.1.3 Type of test specimen and dimensions,
represents five individual determinations. Each laboratory was
12.1.4 Conditioning procedure used,
asked to submit three test results, from a single operator, for
12.1.5 Atmospheric conditions in test room,
each material. Practice E691 was followed for the design and
12.1.6 Number of specimens tested; for anisotropic
analysis of the data; the details are given in ASTM Research
materials, the number of specimens tested and the direction in
Report No. D20-1170.
which they were tested,
13.1.3 The precision of this test method is very dependent
12.1.7 Speed of testing,
upon the uniformity of specimen preparation, standard prac-
12.1.8 Classification of extensometers used. A description
tices for which are covered in other documents.
of measuring technique and calculations employed instead of a
13.2 Bias—There are no recognized standards on which to
minimum Class-C extensometer system,
base an estimate of bias for this test method.
12.1.9 Tensile strength at yield or break, average value, and
standard deviation,
13.3 Warning—The data in Tables 2-10 shall not be rigor-
12.1.10 Tensile stress at yield or break, if applicable,
ously applied to acceptance or rejection of material, as those
average value, and standard deviation,
data are specific to the interlaboratory study and are not
12.1.11 Percent elongation at yield, or break, or nominal
necessarily representative of other lots, conditions, materials,
strain at break, or all three, as applicable, average value, and
or laboratories. Users of this test method shall apply the
standard deviation,
12.1.12 Modulus of elasticity or secant modulus, average
Supporting data are available from ASTM Headquarters. Request RR:D20-
value, and standard deviation,
1125 for the 1984 round robin and RR:D20-1170 for the 1988 round robin.
12.1.13 If measured, Poisson’s ratio, average value, stan-
darddeviation,andstatementofwhethertherewasproportion-
TABLE 3 Tensile Stress at Break, 10 psi, for Eight Laboratories,
ality within the strain range,
A
Five Materials
12.1.14 Date of test, and
Mean S S I I
r R r R
12.1.15 Revision date of Test Method D638.
Polypropylene 2.97 1.54 1.65 4.37 4.66
Cellulose acetate butyrate 4.82 0.058 0.180 0.164 0.509
Acrylic 9.09 0.452 0.751 1.27 2.13
Glass-reinforced polyester 20.8 0.233 0.437 0.659 1.24
TABLE 2 Modulus, 10 psi, for Eight Laboratories, Five Materials
Glass-reinforced nylon 23.6 0.277 0.698 0.784 1.98
Mean S S I I A
r R r R
Tensile strength and elongation at break values obtained for unreinforced
Polypropylene 0.210 0.0089 0.071 0.025 0.201
propylene plastics generally are highly variable due to inconsistencies in necking
Cellulose acetate butyrate 0.246 0.0179 0.035 0.051 0.144 or “drawing” of the center section of the test bar. Since tensile strength and
Acrylic 0.481 0.0179 0.063 0.051 0.144
elongation at yield are more reproducible and relate in most cases to the practical
Glass-reinforced nylon 1.17 0.0537 0.217 0.152 0.614 usefulness of a molded part, they are generally recommended for specification
Glass-reinforced polyester 1.39 0.0894 0.266 0.253 0.753
purposes.
D638 − 22
TABLE 4 Elongation at Break, %, for Eight Laboratories, Five TABLE 7 Tensile Break Stress, for Nine Laboratories, Six
A
Materials Materials
Mean S S I I
r R r R Test
Values Expressed in psi Units
Material Speed,
Glass-reinforced polyester 3.68 0.20 2.33 0.570 6.59
Average S S rR
in./min r R
Glass-reinforced nylon 3.87 0.10 2.13 0.283 6.03
Acrylic 13.2 2.05 3.65 5.80 10.3
LDPE 20 1592 52.3 74.9 146.4 209.7
Cellulose acetate butyrate 14.1 1.87 6.62 5.29 18.7
LDPE 20 1750 66.6 102.9 186.4 288.1
Polypropylene 293.0 50.9 119.0 144.0 337.0
LLDPE 20 4379 127.1 219.0 355.8 613.3
LLDPE 20 2840 78.6 143.5 220.2 401.8
A
Tensile strength and elongation at break values obtained for unreinforced
LLDPE 20 1679 34.3 47.0 95.96 131.6
propylene plastics generally are highly variable due to inconsistencies in necking
LLDPE 20 2660 119.1 166.3 333.6 465.6
or “drawing” of the center section of the test bar. Since tensile strength and
elongation at yield are more reproducible and relate in most cases to the practical
usefulness of a molded part, they are generally recommended for specification
purposes.
TABLE 8 Tensile Break Elongation, for Nine Laboratories, Six
Materials
Test
Values Expressed in Percent Units
TABLE 5 Tensile Yield Stress, for Ten Laboratories, Eight
Material Speed,
Materials
Average S S rR
in./min r R
Test
Values Expressed in psi Units LDPE 20 567 31.5 59.5 88.2 166.6
Material Speed,
LDPE 20 569 61.5 89.2 172.3 249.7
Average S S rR
in./min r R
LLDPE 20 890 25.7 113.8 71.9 318.7
LLDPE 20 64.4 6.68 11.7 18.7 32.6
LDPE 20 1544 52.4 64.0 146.6 179.3
LLDPE 20 803 25.7 104.4 71.9 292.5
LDPE 20 1894 53.1 61.2 148.7 171.3
LLDPE 20 782 41.6 96.7 116.6 270.8
LLDPE 20 1879 74.2 99.9 207.8 279.7
LLDPE 20 1791 49.2 75.8 137.9 212.3
LLDPE 20 2900 55.5 87.9 155.4 246.1
LLDPE 20 1730 63.9 96.0 178.9 268.7
TABLE 9 Tensile Stress at Yield, 10 psi, for Eight Laboratories,
HDPE 2 4101 196.1 371.9 549.1 1041.3
Three Materials
HDPE 2 3523 175.9 478.0 492.4 1338.5
Mean S S I I
r R r R
Polypropylene 3.63 0.022 0.161 0.062 0.456
Cellulose acetate butyrate 5.01 0.058 0.227 0.164 0.642
TABLE 6 Tensile Yield Elongation, for Eight Laboratories, Eight
Acrylic 10.4 0.067 0.317 0.190 0.897
Materials
Test
Values Expressed in Percent Units
Material Speed,
Average S S rR TABLE 10 Elongation at Yield, %, for Eight Laboratories, Three
in./min r R
Materials
LDPE 20 17.0 1.26 3.16 3.52 8.84
LDP
...