ASTM E8 - E 8M - 24

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Designation: E8/E8M −24 American Association State
Highway and Transportation Officials Standard
AASHTO No.: T68
An American National Standard
Standard Test Methods for
Tension Testing of Metallic Materials
1
This standard is issued under the ﬁxed designation E8/E8M; 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 tension testing of metallic
materials in any form at room temperature, speciﬁcally, the
methods of determination of yield strength, yield point
elongation, tensile strength, elongation, and reduction of area.
1.2 The gauge lengths for most round specimens are re-
quired to be 4D for E8 and 5D for E8M. The gauge length is
the most signiﬁcant difference between E8 and E8M test
specimens. Test specimens made from powder metallurgy
(P/M) materials are exempt from this requirement by industry-
wide agreement to keep the pressing of the material to a
speciﬁc projected area and density.
1.3 Exceptions to the provisions of these test methods may
need to be made in individual speciﬁcations or test methods for
a particular material. For examples, see Test Methods and
Deﬁnitions A370 and Test Methods B557, and B557M.
1.4 Room temperature shall be considered to be 10 °C to
38 °C [50 °F to 100°F] unless otherwise speciﬁed.
1.5 The values stated in SI units are to be regarded as
separate from inch/pound units. The values stated in each
system are not exact equivalents; therefore each system must
be used independently of the other. Combining values from the
two systems may result in non-conformance with the 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
A356/A356M Speciﬁcation for Steel Castings, Carbon, Low
Alloy, and Stainless Steel, Heavy-Walled for Steam Tur-
bines
A370 Test Methods and Deﬁnitions for Mechanical Testing
of Steel Products
B557 Test Methods for Tension Testing Wrought and Cast
Aluminum- and Magnesium-Alloy Products
B557M Test Methods for Tension Testing Wrought and Cast
Aluminum- and Magnesium-Alloy Products (Metric)
E4 Practices for Force Calibration and Veriﬁcation of Test-
ing Machines
E6 Terminology Relating to Methods of Mechanical Testing
E29 Practice for Using Signiﬁcant Digits in Test Data to
Determine Conformance with Speciﬁcations
E83 Practice for Veriﬁcation and Classiﬁcation of Exten-
someter Systems
E345 Test Methods of Tension Testing of Metallic Foil
E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
E1012 Practice for Veriﬁcation of Testing Frame and Speci-
men Alignment Under Tensile and Compressive Axial
Force Application
D1566 Terminology Relating to Rubber
E1856 Guide for Evaluating Computerized Data Acquisition
Systems Used to Acquire Data from Universal Testing
Machines
E2658 Practices for Veriﬁcation of Speed for Material Test-
ing Machines
1
These test methods are under the jurisdiction of ASTM Committee E28 on
Mechanical Testing and are the direct responsibility of Subcommittee E28.04 on
Uniaxial Testing.
Current edition approved Jan. 1, 2024. Published March 2024. Originally
approved in 1924. Last previous edition approved 2022 as E8/E8M – 22.
DOI: 10.1520/E0008_E0008M-24.
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.
*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
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

2.2 ISO/ASTM Standard:

ISO/ASTM 52909:2024(en) Additive manufacturing of met-

als — Finished part properties — Orientation and location

dependence of mechanical properties for metal parts

3. Terminology

3.1 Deﬁnitions of Terms Common to Mechanical Testing—

3.1.1 The deﬁnitions of mechanical testing terms that ap-

pear in the Terminology E6 apply to this test method.

3.1.1.1 These terms include bending strain, constraint,

elongation, extensometer, force, gauge length, necking, re-

duced section, stress-strain diagram, testing machine, and

modulus of elasticity.

3.1.2 In addition, the following common terms from Termi-

nology E6 are deﬁned:

3.1.3 discontinuous yielding, n—in a uniaxial test, a hesita-

tion or ﬂuctuation of force observed at the onset of plastic

deformation, due to localized yielding.

3.1.3.1 Discussion—The stress-strain curve need not appear

to be discontinuous.

3.1.4 elongation after fracture, n—the elongation measured

by ﬁtting the two halves of the broken specimen together.

3.1.5 elongation at fracture, n—the elongation measured

just prior to the sudden decrease in force associated with

fracture.

3.1.6 lower yield strength, LYS [FL

-2

]—in a uniaxial test,

the minimum stress recorded during discontinuous yielding,

ignoring transient effects.

3.1.7 reduced parallel section, A, n—the central portion of

the specimen that has a nominally uniform cross section, with

an optional small taper toward the center, that is smaller than

that of the ends that are gripped, not including the ﬁllets.

3.1.7.1 Discussion—This term is often called the parallel

length in other standards.

3.1.7.2 Discussion—Previous versions of E8/E8M deﬁned

this term as “reduced section.”

3.1.8 reduction of area, n—the difference between the

original cross-sectional area of a tension test specimen and the

area of its smallest cross section.

3.1.8.1 Discussion—The reduction of area is usually ex-

pressed as a percentage of the original cross-sectional area of

the specimen.

3.1.8.2 Discussion—The smallest cross section may be mea-

sured at or after fracture as speciﬁed for the material under test.

3.1.8.3 Discussion—The term reduction of area when ap-

plied to metals generally means measurement after fracture;

when applied to plastics and elastomers, measurement at

fracture. Such interpretation is usually applicable to values for

reduction of area reported in the literature when no further

qualiﬁcation is given. (E28.04)

3.1.9 tensile strength, S

[FL

–2

], n—the maximum tensile

stress that a material is capable of sustaining.

3.1.9.1 Discussion—Tensile strength is calculated from the

maximum force during a tension test carried to rupture and the

original cross-sectional area of the specimen.

3.1.10 uniform elongation, El

, [%]—the elongation deter-

mined at the maximum force sustained by the test specimen

just prior to necking or fracture, or both.

3.1.10.1 Discussion—Uniform elongation includes both

elastic and plastic elongation.

3.1.11 upper yield strength, UYS [FL

-2

]—in a uniaxial test,

the ﬁrst stress maximum (stress at ﬁrst zero slope) associated

with discontinuous yielding at or near the onset of plastic

deformation.

3.1.12 yield point elongation, YPE, n—in a uniaxial test, the

strain (expressed in percent) separating the stress-strain curve’s

ﬁrst point of zero slope from the point of transition from

discontinuous yielding to uniform strain hardening.

3.1.12.1 Discussion— If the transition occurs over a range

of strain, the YPE end point is the intersection between (a) a

horizontal line drawn tangent to the curve at the last zero slope

and (b) a line drawn tangent to the strain hardening portion of

the stress-strain curve at the point of inﬂection. If there is no

point at or near the onset of yielding at which the slope reaches

zero, the material has 0 % YPE.

3.1.13 yield strength, YS or S

[FL

–2

], n—the engineering

stress at which, by convention, it is considered that plastic

elongation of the material has commenced.

3.1.13.1 Discussion—This stress may be speciﬁed in terms

of (a) a speciﬁed deviation from a linear stress-strain

relationship, (b) a speciﬁed total extension attained, or (c)

maximum or minimum engineering stresses measured during

discontinuous yielding.

3.2 Deﬁnitions of Terms Speciﬁc to This Standard:

3.2.1 referee test, n—test made to settle a disagreement as to

the conformance to speciﬁed requirements, or conducted by a

third party to arbitrate between conﬂicting results. D1566,

D11.08

4. Signiﬁcance and Use

4.1 Tension tests provide information on the strength and

ductility of materials under uniaxial tensile stresses. This

information may be useful in comparisons of materials, alloy

development, quality control, and design under certain circum-

stances.

4.2 The results of tension tests of specimens machined to

standardized dimensions from selected portions of a part or

material may not totally represent the strength and ductility

properties of the entire end product or its in-service behavior in

different environments.

4.3 These test methods are considered satisfactory for ac-

ceptance testing of commercial shipments. The test methods

have been used extensively in the trade for this purpose.

5. Apparatus

5.1 Testing Machines—Machines used for tension testing

shall conform to the requirements of Practices E4. The forces

used in determining tensile strength and yield strength shall be

Available from International Organization for Standardization (ISO), ISO

Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,

Switzerland, https://www.iso.org.

E8/E8M − 24

within the veriﬁed force application range of the testing
machine as deﬁned in Practices E4. Where veriﬁcation of the
testing machine speed is required, Practices E2658 shall be
used unless otherwise speciﬁed.
5.2 Gripping Devices:
5.2.1 General—Various types of gripping devices may be
used to transmit the measured force applied by the testing
machine to the test specimens. To ensure axial tensile stress
within the gauge length, the axis of the test specimen should
coincide with the center line of the heads of the testing
machine. Any departure from this requirement may introduce
bending stresses that are not included in the usual stress
computation (force divided by cross-sectional area).
NOTE 1—The effect of this eccentric force application may be illus-
trated by calculating the bending moment and stress thus added. For a
standard 12.5 mm [0.500 in.] diameter specimen, the stress increase is 1.5
percentage points for each 0.025 mm [0.001 in.] of eccentricity. This error
increases to 2.5 percentage points/ 0.025 mm [0.001 in.] for a 9 mm
[0.350 in.] diameter specimen and to 3.2 percentage points/ 0.025 mm
[0.001 in.] for a 6 mm [0.250 in.] diameter specimen.
NOTE 2—Alignment methods are given in Practice E1012.
5.2.2 Wedge Grips—Testing machines usually are equipped
with wedge grips. These wedge grips generally furnish a
satisfactory means of gripping long specimens of ductile metal
and ﬂat plate test specimens such as those shown in Fig. 1. If,
however, for any reason, one grip of a pair advances farther
than the other as the grips tighten, an undesirable bending
stress may be introduced. When liners are used behind the
wedges, they must be of the same thickness and their faces
must be ﬂat and parallel. For best results, the wedges should be
supported over their entire lengths by the heads of the testing
machine. This requires that liners of several thicknesses be
available to cover the range of specimen thickness. For proper
gripping, it is desirable that the entire length of the serrated
face of each wedge be in contact with the specimen. Proper
alignment of wedge grips and liners is illustrated in Fig. 2. For
short specimens and for specimens of many materials it is
generally necessary to use machined test specimens and to use
a special means of gripping to ensure that the specimens, when
under load, shall be as nearly as possible in uniformly
distributed pure axial tension (see 5.2.3,5.2.4, and 5.2.5).
5.2.3 Grips for Threaded and Shouldered Specimens and
Brittle Materials—A schematic diagram of a gripping device
for threaded-end specimens is shown in Fig. 3, while Fig. 4
shows a device for gripping specimens with shouldered ends.
Both of these gripping devices should be attached to the heads
of the testing machine through properly lubricated spherical-
seated bearings. The distance between spherical bearings
should be as great as feasible.
5.2.4 Grips for Sheet Materials—The self-adjusting grips
shown in Fig. 5 have proven satisfactory for testing sheet
materials that cannot be tested satisfactorily in the usual type of
wedge grips.
5.2.5 Grips for Wire—Grips of either the wedge or snubbing
types as shown in Fig. 5 and Fig. 6 or ﬂat wedge grips may be
used.
5.3 Dimension-Measuring Devices—Micrometers and other
devices used for measuring linear dimensions shall be accurate
and precise to at least one half the smallest unit to which the
individual dimension is required to be measured.
5.4 Extensometers—Extensometers used in tension testing
shall conform to the requirements of Practice E83 for the
classiﬁcations speciﬁed by the procedure section of this test
method. Extensometers shall be used and veriﬁed to include
the strains corresponding to the yield strength and elongation at
fracture (if determined).
5.4.1 Extensometers with gauge lengths equal to or shorter
than the nominal gauge length of the specimen (dimension
shown as “G-Gauge Length” in the accompanying ﬁgures) may
be used to determine the yield behavior. For specimens without
a reduced section (for example, full cross sectional area
specimens of wire, rod, or bar), the extensometer gauge length
for the determination of yield behavior shall not exceed 80 %
of the distance between grips. For measuring elongation at
fracture with an appropriate extensometer, the gauge length of
the extensometer shall be equal to the nominal gauge length
required for the specimen being tested.
6. Test Specimens
6.1 General:
6.1.1 Specimen Size—Test specimens shall be either sub-
stantially full size or machined, as prescribed in the product
speciﬁcations for the material being tested.
6.1.2 Location—Unless otherwise speciﬁed, the axis of the
test specimen shall be located within the parent material as
follows:
6.1.2.1 At the center for products 40 mm [1.500 in.] or less
in thickness, diameter, or distance between ﬂats.
6.1.2.2 Midway from the center to the surface for products
over 40 mm [1.500 in.] in thickness, diameter, or distance
between ﬂats.
6.1.3 Specimen Machining—Improperly prepared test speci-
mens often are the reason for unsatisfactory and incorrect test
results. It is important, therefore, that care be exercised in the
preparation of specimens, particularly in the machining, to
maximize precision and minimize bias in test results.
6.1.3.1 The reduced section including the ﬁllets of prepared
specimens should be free of cold work, notches, chatter marks,
grooves, gouges, burrs, rough surfaces or edges, overheating,
or any other condition which can deleteriously affect the
properties to be measured.
NOTE 3—Punching or blanking of the reduced section may produce
signiﬁcant cold work or shear burrs, or both, along the edges which should
be removed by machining.
6.1.3.2 Within the reduced parallel section of rectangular
specimens, edges or corners should not be ground or abraded in
a manner which could cause the actual cross-sectional area of
the specimen to be signiﬁcantly different from the calculated
area.
6.1.3.3 For brittle materials, large radius ﬁllets at the ends of
the reduced parallel section should be used.
6.1.3.4 The cross-sectional area of the specimen should be
smallest at the center of the reduced parallel section to ensure
fracture within the gauge length. For this reason, a small taper
is permitted in the reduced parallel section of each of the
specimens described in the following sections.
E8/E8M − 24
3

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摘要：

ASTM E8 - E 8M - 24 是金属材料拉伸试验的最新标准规范，由美国材料与试验协会发布，涵盖室温下金属材料拉伸性能的测试方法，包括屈服强度、抗拉强度、伸长率和断面收缩率等关键参数的测定。该标准统一了英制和公制单位（E8 与 E8M），适用于板材、棒材、管材、线材等多种金属制品的质量控制与研发验证。2024 年版整合了近年来的技术修订与澄清要求，确保测试结果在不同实验室间的可重复性、可比性与合规性。对于从事金属材料生产、制造、检验以及进出口贸易的专业人士而言，掌握 ASTM E8 -

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