EN ISO 6892-1:2016

SLOVENSKI STANDARD
01-februar-2017
1DGRPHãþD
SIST EN ISO 6892-1:2010
Kovinski materiali - Natezni preskus - 1. del: Metoda preskušanja pri sobni
temperaturi (ISO 6892-1:2016)
Metallic materials - Tensile testing - Part 1: Method of test at room temperature (ISO
6892-1:2016)
Metallische Werkstoffe - Zugversuch - Teil 1: Prüfverfahren bei Raumtemperatur (ISO
6892-1:2016)
Matériaux métalliques - Essai de traction - Partie 1: Méthode d'essai à température
ambiante (ISO 6892-1:2016)
Ta slovenski standard je istoveten z: EN ISO 6892-1:2016
ICS:
77.040.10 Mehansko preskušanje kovin Mechanical testing of metals
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 6892-1
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2016
EUROPÄISCHE NORM
ICS 77.040.10 Supersedes EN ISO 6892-1:2009
English Version
Metallic materials - Tensile testing - Part 1: Method of test
at room temperature (ISO 6892-1:2016)
Matériaux métalliques - Essai de traction - Partie 1: Metallische Werkstoffe - Zugversuch - Teil 1:
Méthode d'essai à température ambiante (ISO 6892- Prüfverfahren bei Raumtemperatur (ISO 6892-1:2016)
1:2016)
This European Standard was approved by CEN on 15 April 2016.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6892-1:2016 E
worldwide for CEN national Members.

Contents Page
European Foreword . 3
European Foreword
This document (EN ISO 6892-1:2016) has been prepared by Technical Committee ISO/TC 164
“Mechanical testing of metals” in collaboration with Technical Committee ECISS/TC 101 “Test methods
for steel (other than chemical analysis)” the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2017, and conflicting national standards shall
be withdrawn at the latest by January 2017.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
This document supersedes EN ISO 6892-1:2009.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 6892-1:2016 has been approved by CEN as EN ISO 6892-1:2016 without any
modification.
INTERNATIONAL ISO
STANDARD 6892-1
Second edition
2016-07-01
Metallic materials — Tensile testing —
Part 1:
Method of test at room temperature
Matériaux métalliques — Essai de traction —
Partie 1: Méthode d’essai à température ambiante
Reference number
ISO 6892-1:2016(E)
©
ISO 2016
ISO 6892-1:2016(E)
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
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Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2016 – All rights reserved

ISO 6892-1:2016(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 6
5 Principle . 7
6 Test pieces . 8
6.1 Shape and dimensions . 8
6.1.1 General. 8
6.1.2 Machined test pieces . 8
6.1.3 Unmachined test pieces . 9
6.2 Types. 9
6.3 Preparation of test pieces . 9
7 Determination of original cross-sectional area . 9
8 Original gauge length and extensometer gauge length .10
8.1 Choice of the original gauge length .10
8.2 Marking the original gauge length .10
8.3 Choice of the extensometer gauge length .10
9 Accuracy of testing apparatus .10
10 Conditions of testing .11
10.1 Setting the force zero point .11
10.2 Method of gripping .11
10.3 Testing rates .11
10.3.1 General information regarding testing rates .11
10.3.2 Testing rate based on strain rate (method A) .11
10.3.3 Testing rate based on stress rate (method B) .13
10.3.4 Report of the chosen testing conditions .15
11 Determination of the upper yield strength .15
12 Determination of the lower yield strength .15
13 Determination of proof strength, plastic extension.15
14 Determination of proof strength, total extension .16
15 Method of verification of permanent set strength .16
16 Determination of the percentage yield point extension .16
17 Determination of the percentage plastic extension at maximum force .17
18 Determination of the percentage total extension at maximum force .17
19 Determination of the percentage total extension at fracture .17
20 Determination of percentage elongation after fracture .18
21 Determination of percentage reduction of area .18
22 Test report .19
23 Measurement uncertainty .20
23.1 General .20
23.2 Test conditions .20
23.3 Test results.20
ISO 6892-1:2016(E)
Annex A (informative) Recommendations concerning the use of computer-controlled
tensile testing machines .34
Annex B (normative) Types of test pieces to be used for thin products: sheets, strips, and
flats between 0,1 mm and 3 mm thick .40
Annex C (normative) Types of test pieces to be used for wire, bars, and sections with a
diameter or thickness of less than 4 mm .43
Annex D (normative) Types of test pieces to be used for sheets and flats of thickness equal
to or greater than 3 mm and wire, bars, and sections of diameter or thickness equal
to or greater than 4 mm .44
Annex E (normative) Types of test pieces to be used for tubes .48
Annex F (informative) Estimation of the crosshead separation rate in consideration of
the stiffness (or compliance) of the testing equipment .50
Annex G (normative) Determination of the modulus of elasticity of metallic materials using
a uniaxial tensile test .52
Annex H (informative) Measuring the percentage elongation after fracture if the specified
value is less than 5 % .61
Annex I (informative) Measurement of percentage elongation after fracture based
on subdivision of the original gauge length .62
Annex J (informative) Determination of the percentage plastic elongation without necking,
A , for long products such as bars, wire, and rods.64
wn
Annex K (informative) Estimation of the uncertainty of measurement .65
Annex L (informative) Precision of tensile testing — Results from interlaboratory programmes .69
Bibliography .76
iv © ISO 2016 – All rights reserved

ISO 6892-1:2016(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 164, Mechanical testing of metals, Subcommittee
SC 1, Uniaxial testing.
This second edition cancels and replaces the first edition (ISO 6892-1:2009), which has been technically
revised with the following changes:
a) renumbering of Clause 10;
b) additional information about the use of Method A and B;
c) new denomination for:
1) Method A closed loop → A1
2) Method A open loop → A2;
e) addition of A.5;
f) addition in Annex F for determination of the stiffness of the testing equipment;
g) new normative Annex G: Determination of the modulus of elasticity of metallic materials using a
uniaxial tensile test;
h) the old Annex G is renamed to Annex H, Annex H to Annex I, etc.
ISO 6892 consists of the following parts, under the general title Metallic materials — Tensile testing:
— Part 1: Method of test at room temperature
— Part 2:Method of test at elevated temperature
— Part 3:Method of test at low temperature
— Part 4: Method of test in liquid helium
ISO 6892-1:2016(E)
Introduction
During discussions concerning the speed of testing in the preparation of ISO 6892, it was decided to
recommend the use of strain rate control in future revisions.
In this part of ISO 6892, there are two methods of testing speeds available. The first, method A, is based
on strain rates (including crosshead separation rate) and the second, method B, is based on stress rates.
Method A is intended to minimize the variation of the test rates during the moment when strain rate
sensitive parameters are determined and to minimize the measurement uncertainty of the test results.
Therefore, and out of the fact that often the strain rate sensitivity of the materials is not known, the use
of method A is strongly recommended.
vi © ISO 2016 – All rights reserved

INTERNATIONAL STANDARD ISO 6892-1:2016(E)
Metallic materials — Tensile testing —
Part 1:
Method of test at room temperature
1 Scope
This part of ISO 6892 specifies the method for tensile testing of metallic materials and defines the
mechanical properties which can be determined at room temperature.
NOTE Annex A contains further recommendations for computer controlled testing machines.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 7500-1, Metallic materials — Verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Verification and calibration of the force-measuring system
ISO 9513, Metallic materials — Calibration of extensometer systems used in uniaxial testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE In what follows, the designations “force” and “stress” or “extension”, “percentage extension”, and
“strain”, respectively, are used on various occasions (as figure axis labels or in explanations for the determination
of different properties). However, for a general description or point on a curve, the designations “force” and
“stress” or “extension”, “percentage extension”, and “strain”, respectively, can be interchanged.
3.1
gauge length
L
length of the parallel portion of the test piece on which elongation is measured at any moment during
the test
3.1.1
original gauge length
L
o
length between gauge length (3.1) marks on the test piece measured at room temperature before the test
3.1.2
final gauge length after fracture
L
u
length between gauge length (3.1) marks on the test piece measured after rupture, at room temperature,
the two pieces having been carefully fitted back together so that their axes lie in a straight line
ISO 6892-1:2016(E)
3.2
parallel length
L
c
length of the parallel reduced section of the test piece
Note 1 to entry: The concept of parallel length is replaced by the concept of distance between grips for
unmachined test pieces.
3.3
elongation
increase in the original gauge length (3.1.1) at any moment during the test
3.4
percentage elongation
elongation expressed as a percentage of the original gauge length (3.1.1)
3.4.1
percentage permanent elongation
increase in the original gauge length (3.1.1) of a test piece after removal of a specified stress, expressed
as a percentage of the original gauge length
3.4.2
percentage elongation after fracture
A
permanent elongation of the gauge length after fracture, (L − L ), expressed as a percentage of the
u o
original gauge length (3.1.1)
Note 1 to entry: For further information, see 8.1.
3.5
extensometer gauge length
L
e
initial extensometer gauge length used for measurement of extension by means of an extensometer
Note 1 to entry: For further information, see 8.3.
3.6
extension
increase in the extensometer gauge length (3.5), at any moment during the test
3.6.1
percentage extension
“strain”
e
extension expressed as a percentage of the extensometer gauge length (3.5)
Note 1 to entry: e is commonly called engineering strain.
3.6.2
percentage permanent extension
increase in the extensometer gauge length, after removal of a specified stress from the test piece,
expressed as a percentage of the extensometer gauge length (3.5)
3.6.3
percentage yield point extension
A
e
in discontinuous yielding materials, the extension between the start of yielding and the start of uniform
work-hardening, expressed as a percentage of the extensometer gauge length (3.5)
Note 1 to entry: See Figure 7.
2 © ISO 2016 – All rights reserved

ISO 6892-1:2016(E)
3.6.4
percentage total extension at maximum force
A
gt
total extension (elastic extension plus plastic extension) at maximum force, expressed as a percentage
of the extensometer gauge length (3.5)
Note 1 to entry: See Figure 1.
3.6.5
percentage plastic extension at maximum force
A
g
plastic extension at maximum force, expressed as a percentage of the extensometer gauge length (3.5)
Note 1 to entry: See Figure 1.
3.6.6
percentage total extension at fracture
A
t
total extension (elastic extension plus plastic extension) at the moment of fracture, expressed as a
percentage of the extensometer gauge length (3.5)
Note 1 to entry: See Figure 1.
3.7 Testing rate
3.7.1
strain rate
e
L
e
increase of strain, measured with an extensometer, in extensometer gauge length (3.5), per time
3.7.2
estimated strain rate over the parallel length

e
L
c
value of the increase of strain over the parallel length (3.2), of the test piece per time based on the
crosshead separation rate (3.7.3) and the parallel length of the test piece
3.7.3
crosshead separation rate
v
c
displacement of the crossheads per time
3.7.4
stress rate

R
increase of stress per time
Note 1 to entry: Stress rate is only used in the elastic part of the test (method B) (see also 10.3.3).
3.8
percentage reduction of area
Z
maximum change in cross-sectional area which has occurred during the test, (S − S ), expressed as a
o u
percentage of the original cross-sectional area, S :
o
SS−
ou
Z = ⋅100
S
o
ISO 6892-1:2016(E)
3.9 Maximum force
3.9.1
maximum force
F
m
highest force that the test piece withstands during
the test
3.9.2
maximum force
F
m
highest force that the test piece withstands during the
test after the beginning of work-hardening
Note 1 to entry: For materials which display discontinuous yielding, but where no work-hardening can be
established, F is not defined in this part of ISO 6892 [see footnote to Figure 8 c)].
m
Note 2 to entry: See Figure 8 a) and b).
3.10
stress
R
at any moment during the test, force divided by the original cross-sectional area, S , of the test piece
o
Note 1 to entry: All references to stress in this part of ISO 6892 are to engineering stress.
3.10.1
tensile strength
R
m
stress corresponding to the maximum force (3.9.2)
3.10.2
yield strength
when the metallic material exhibits a yield phenomenon, stress corresponding to the point reached
during the test at which plastic deformation occurs without any increase in the force
3.10.2.1
upper yield strength
R
eH
maximum value of stress (3.10) prior to the first decrease in force
Note 1 to entry: See Figure 2.
3.10.2.2
lower yield strength
R
eL
lowest value of stress (3.10) during plastic yielding, ignoring any initial transient effects
Note 1 to entry: See Figure 2.
3.10.3
proof strength, plastic extension
R
p
stress at which the plastic extension is equal to a specified percentage of the extensometer gauge
length (3.5)
Note 1 to entry: Adapted from ISO/TR 25679:2005, “proof strength, non-proportional extension”.
Note 2 to entry: A suffix is added to the subscript to indicate the prescribed percentage, e.g. R .
p0,2
Note 3 to entry: See Figure 3.
4 © ISO 2016 – All rights reserved

ISO 6892-1:2016(E)
3.10.4
proof strength, total extension
R
t
stress at which total extension (elastic extension plus plastic extension) is equal to a specified
percentage of the extensometer gauge length (3.5)
Note 1 to entry: A suffix is added to the subscript to indicate the prescribed percentage, e.g. R .
t0,5
Note 2 to entry: See Figure 4.
3.10.5
permanent set strength
R
r
stress at which, after removal of force, a specified permanent elongation or extension, expressed
respectively as a percentage of original gauge length (3.1.1), or extensometer gauge length (3.5), has not
been exceeded
Note 1 to entry: A suffix is added to the subscript to indicate the specified percentage of the original gauge length,
L , or of the extensometer gauge length, L , e.g. R .
o e r0,2
Note 2 to entry: See Figure 5.
3.11
fracture
phenomenon which is deemed to occur when total separation of the test piece occurs
Note 1 to entry: Criteria for fracture for computer controlled tests are given in Figure A.2.
3.12
computer-controlled tensile testing machine
machine for which the control and monitoring of the test, the measurements, and the data processing
are undertaken by computer
3.13
modulus of elasticity
E
quotient of change of stress ΔR and change of percentage extension Δe in the range of evaluation,
multiplied by 100 %
DR
E =⋅100 %
De
Note 1 to entry: It is recommended to report the value in GPa rounded to the nearest 0,1 GPa and according to
ISO 80000-1.
3.14
default value
lower or upper value for stress respectively strain which is used for the description of the range where
the modulus of elasticity is calculated
3.15
coefficient of correlation
R
additional result of the linear regression which describes the quality of the stress-strain curve in the
evaluation range
Note 1 to entry: The used symbol R is a mathematical representation of regression and is no expression for a
squared stress value.
ISO 6892-1:2016(E)
3.16
standard deviation of the slope
S
m
additional result of the linear regression which describes the difference of the stress values from the
best fit line for the given extension values in the evaluation range
3.17
relative standard deviation of the slope
S
m(rel)
quotient of the standard deviation of the slope and the slope in the evaluation range, multiplied by 100 %
S
m
S =⋅100 %
m(rel)
E
4 Symbols
The symbols used in this part of ISO 6892 and corresponding designations are given in Table 1.
Table 1 — Symbols and designations
Symbol Unit Designation
Test piece
a
a , T mm original thickness of a flat test piece or wall thickness of a tube
o
original width of the parallel length of a flat test piece or average width of the longi-
b mm
o
tudinal strip taken from a tube or width of flat wire
original diameter of the parallel length of a circular test piece, or diameter of round
d mm
o
wire or internal diameter of a tube
D mm original external diameter of a tube
o
L mm original gauge length
o
initial gauge length for determination of A (see Annex J)
wn
¢ mm
L
o
L mm parallel length
c
L mm extensometer gauge length
e
L mm total length of test piece
t
L mm final gauge length after fracture
u
final gauge length after fracture for determination of A (see Annex J)
wn
¢ mm
L
u
S mm original cross-sectional area of the parallel length
o
S mm minimum cross-sectional area after fracture
u
k — coefficient of proportionality (see 6.1.1)
Z % percentage reduction of area
Elongation
A % percentage elongation after fracture (see 3.4.2)
A % percentage plastic elongation without necking (see Annex J)
wn
Extension
e % extension
A % percentage yield point extension
e
A % percentage plastic extension at maximum force, F
g m
A % percentage total extension at maximum force, F
gt m
A % percentage total extension at fracture
t
ΔL mm extension at maximum force
m
6 © ISO 2016 – All rights reserved

ISO 6892-1:2016(E)
Table 1 (continued)
Symbol Unit Designation
ΔL mm extension at fracture
f
Rates
 −1
e
s strain rate
L
e
−1

e s estimated strain rate over the parallel length
L
c
−1 stress rate
 MPa s
R
−1
v mm s crosshead separation rate
c
Force
F N maximum force
m
Yield strength — Proof strength — Tensile strength
b
R MPa stress
R MPa upper yield strength
eH
R MPa lower yield strength
eL
R MPa tensile strength
m
R MPa proof strength, plastic extension
p
R MPa specified permanent set strength
r
R MPa proof strength, total extension
t
Modulus of Elasticity — slope of the stress-percentage extension curve
c
E GPa modulus of elasticity
m MPa slope of the stress-percentage extension curve at a given moment of the test
d
m MPa slope of the elastic part of the stress-percentage extension curve
E
R MPa lower stress value
R MPa upper stress value
e % lower strain value
e % upper strain value
R — coefficient of correlation
S MPa standard deviation of the slope
m
S % relative standard deviation of the slope
m(rel)
a
Symbol used in steel tube product standards.
b −2
1 MPa = 1 N mm .
c
The calculation of the modulus of elasticity is described in Annex G. It is not required to use Annex G to
determine the slope of the elastic part of the stress-percentage extension curve for the determination of proof
strength.
d
In the elastic part of the stress-percentage extension curve, the value of the slope may not necessarily
represent the modulus of elasticity. This value may closely agree with the value of the modulus of elasticity if
optimal conditions are used (see Annex G).
CAUTION — The factor 100 is necessary if percentage values are used.
5 Principle
The test involves straining a test piece by tensile force, generally to fracture, for the determination of
one or more of the mechanical properties defined in Clause 3.
The test shall be carried out at room temperature between 10 °C and 35 °C, unless otherwise specified.
For laboratory environments outside the stated requirement, it is the responsibility of the testing
laboratory to assess the impact on testing and or calibration data produced with and for testing
ISO 6892-1:2016(E)
machines operated in such environments. When testing and calibration activities are performed
outside the recommended temperature limits of 10 °C and 35 °C, the temperature shall be recorded
and reported. If significant temperature gradients are present during testing and or calibration,
measurement uncertainty may increase and out of tolerance conditions may occur.
Tests carried out under controlled conditions shall be made at a temperature of 23 °C ± 5 °C.
If the determination of the modulus of elasticity is requested in the tensile test, this shall be done in
accordance with Annex G.
6 Test pieces
6.1 Shape and dimensions
6.1.1 General
The shape and dimensions of the test pieces may be constrained by the shape and dimensions of the
metallic product from which the test pieces are taken.
The test piece is usually obtained by machining a sample from the product or a pressed blank or casting.
However, products of uniform cross-section (sections, bars, wires, etc.) and also as-cast test pieces (i.e.
for cast iron and non-ferrous alloys) may be tested without being machined.
The cross-section of the test pieces may be circular, square, rectangular, annular or, in special cases,
some other uniform cross-section.
Preferred test pieces have a direct relationship between the original gauge length, L , and the original
o
cross-sectional area, S , expressed by the formula L = kS , where k is a coefficient of proportionality,
o o
o
and are called proportional test pieces. The internationally adopted value for k is 5,65. The original
gauge length shall be not less than 15 mm. When the cross-sectional area of the test piece is too small
for this requirement to be met with, k = 5,65, a higher value (preferably 11,3) or a non-proportional test
piece may be used.
NOTE By using an original gauge length smaller than 20 mm, the uncertainty of the result “elongation after
fracture” will be increased.
For non-proportional test pieces, the original gauge length, L , is independent of the original cross-
o
sectional area, S .
o
The dimensional tolerances of the test pieces shall be in accordance with the Annexes B to E (see 6.2).
Other test pieces such as those specified in relevant product standards or national standards may be
[1] [2] [6]
used by agreement with the customer, e.g. ISO 3183 , (API 5L), ISO 11960 , (API 5CT), ASTM A370 ,
[7] [10] [13] [14]
ASTM E8M , DIN 50125 , IACS W2 , and JIS Z 2241 .
6.1.2 Machined test pieces
Machined test pieces shall incorporate a transition radius between the gripped ends and the parallel
length if these have different dimensions. The dimensions of the transition radius are important and it is
recommended that they be defined in the material specification if they are not given in the appropriate
annex (see 6.2).
The gripped ends may be of any shape to suit the grips of the testing machine. The axis of the test piece
shall coincide with the axis of application of the force.
The parallel length, L , or, in the case where the test piece has no transition radii, the free length
c
between the grips, shall always be greater than the original gauge length, L .
o
8 © ISO 2016 – All rights reserved

ISO 6892-1:2016(E)
6.1.3 Unmachined test pieces
If the test piece consists of an unmachined length of the product or of an unmachined test bar, the free
length between the grips shall be sufficient for gauge marks to be at a reasonable distance from the
grips (see Annexes B to E).
As-cast test pieces shall incorporate a transition radius between the gripped ends and the parallel
length. The dimensions of this transition radius are important and it is recommended that they be
defined in the product standard. The gripped ends may be of any shape to suit the grips of the testing
machine provided that they enable the centre of the test piece to coincide with the axis of application of
force. The parallel length, L , shall always be greater than the original gauge length, L .
c o
6.2 Types
The main types of test pieces are defined in Annexes B to E according to the shape and type of product,
as shown in Table 2. Other types of test pieces can be specified in product standards.
Table 2 — Main types of test pieces according to product type
Dimensions in millimetres
Corresponding
Type of product
Annex
Sheets — Plates — Flats Wire — Bars — Sections

Thickness Diameter or side
a
0,1 ≤ a < 3 — B
— <4 C
a ≥ 3 ≥4 D
Tubes E
6.3 Preparation of test pieces
The test pieces shall be taken and prepared in accordance with the requirements of the relevant
International Standards for the different materials (e.g. ISO 377).
7 Determination of original cross-sectional area
The relevant dimensions of the test piece should be measured at sufficient cross-sections perpendicular
to the longitudinal axis in the central region of the parallel length of the test piece.
A minimum of three cross-sections is recommended.
The original cross-sectional area, S , is the average cross-sectional area and shall be calculated from
o
the measurements of the appropriate dimensions.
The accuracy of this calculation depends on the nature and type of the test piece. Annexes B to E
describe methods for the evaluation of S for different types of test pieces and contain specifications for
o
the accuracy of measurement.
All measuring devices used for the determination of the original cross-sectional area shall be calibrated
to the appropriate reference standards with traceability to a National Measurement System.
ISO 6892-1:2016(E)
8 Original gauge length and extensometer gauge length
8.1 Choice of the original gauge length
For proportional test pieces, if the original gauge length is not equivalent to 56, 5 S where S is the
o
o
original cross-sectional area of the parallel length, the symbol A should be supplemented by a subscript
indicating the coefficient of proportionality used, e.g. A indicates a percentage elongation of the
11,3
gauge length, L , according to Formula (1):
o
AS=11,3 (1)
11,3 o
NOTE 56,/55SS= 4 p .
oo
For non-proportional test pieces (see Annex B), the symbol A should be supplemented by a subscript
indicating the original gauge length used, expressed in millimetres, e.g. A indicates a percentage
80 mm
elongation of a gauge length, L , of 80 mm.
o
8.2 Marking the original gauge length
For the manual determination of the elongation after fracture A, each end of the original gauge length,
L , shall be marked by means of fine marks, scribed lines, or punch marks, but not by marks which
o
could result in premature fracture. The original gauge length shall be marked to an accuracy of ±1 %.
For proportional test pieces, the calculated value of the original gauge length may be rounded to the
nearest multiple of 5 mm, provided that the difference between the calculated and marked gauge length
is less than 10 % of L .
o
If the parallel length, L , is much greater than the original gauge length, as, for instance, with
c
unmachined test pieces, a series of overlapping gauge lengths may be marked.
In some cases, it may be helpful to draw a line parallel to the longitudinal axis, along which the gauge
lengths are marked.
8.3 Choice of the extensometer gauge length
For measurement of yield and proof strength parameters, L should span as much of the parallel length
e
of the test piece as possible. Ideally, as a minimum, L should be greater than 0,50L but less than
e o
approximately 0,9L . This should ensure that the extensometer detects all yielding events that occur
c
in the test piece. Further, for measurement of parameters “at” or “after reaching” maximum force, L
e
should be approximately equal to L .
o
9 Accuracy of testing apparatus
The force-measuring system of the testing machine shall be in accordance with ISO 7500-1, class 1,
or better.
For the determination of proof strength (plastic or total extension), the extensometer used shall be in
accordance with ISO 9513, class 1 or better, in the relevant range. For other properties (with extensions
greater than 5 %), an ISO 9513, class 2 extensometer in the relevant range may be used.
10 © ISO 2016 – All rights reserved

ISO 6892-1:2016(E)
10 Conditions of testing
10.1 Setting the force zero point
The force-measuring system shall be set to zero after the testing loading train has been assembled, but
before the test piece is actually gripped at both ends. Once the force zero point has been set, the force-
measuring system shall not be changed in any way during the test.
NOTE The use of this method ensures that, on one hand, the weight of the gripping system is compensated
for in the force measurement, and on the other hand, any force resulting from the clamping operation does not
affect this measurement.
10.2 Method of gripping
The test pieces shall be gripped by suitable means, such as wedges, screwed grips, parallel jaw faces, or
shouldered holders.
Every endeavour should be made to ensure that test pieces are held in such a way that the force is applied
[8]
as axially as possible, in order to minimize bending (more information is given in ASTM E1012 , for
example). This is of particular importance when testing brittle materials or when determining proof
strength (plastic extension), proof strength (total exten
...