ISO/FDIS 25408-1

• Abstract:

  This document specifies test methods of round steel Bead Wires which are used for tyre reinforcement.Test methods on Mechanical properties and Chemical properties (coating analysis) are included. By agreement, these test methods may be applied to similar single filaments used for reinforcing other rubber products.

• Status: Not Published
• ICS: 77.140.65 - Steel wire, wire ropes and link chains
• ICS: 83.140.01 - Rubber and plastics products in general
• ICS: 83.160.01 - Tyres in general
• Technical Committee: ISO/TC 17/SC 17 - Steel wire rod and wire products
• Drafting Committee: ISO/TC 17/SC 17 - Steel wire rod and wire products
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 26-Aug-2026
• Completion Date: 26-Aug-2026

Overview

ISO/FDIS 25408-1:2026 – Testing method for bead wire – Part 1: General requirements specifies standardized test methods for round steel bead wires used in tyre reinforcement. This international standard by ISO covers both mechanical and chemical property testing, including coating analysis, and offers the flexibility to apply these methods, by agreement, to similar single filaments for other rubber reinforcement applications. Establishing clear general requirements for testing bead wire ensures consistency, reliability, and international harmonization across industries relying on steel wire reinforcement.

Key Topics

This standard addresses several critical aspects of bead wire testing:

• Mechanical Property Testing: Procedures for measuring diameter, out-of-roundness, maximum force, yield strength, tensile strength, elongation at fracture, bend testing, torsion testing, and residual torsions.
• Chemical Property Testing: Guidelines for coating analysis, specifically using X-ray fluorescence spectroscopy to evaluate mass and composition of bronze coatings.
• Test Method Precision: Defines acceptable limits for variation (coefficient of variation) for key properties, supporting reliable and reproducible results.
• Test Equipment and Preparation: Specifies apparatus requirements (e.g., micrometer, laser measurement devices, tensile testers, bend and torsion testers) and standardized sample preparation.
• Reporting and Result Expression: Outlines methods for calculating results, presenting data, and reporting parameters such as diameter, force, and torsions.

Applications

ISO/FDIS 25408-1:2026 provides practical value for multiple stakeholders in the tyre manufacturing and rubber reinforcement sectors:

• Tyre Manufacturing: Ensures that steel bead wires used for tyre reinforcement meet stringent mechanical and chemical properties, leading to improved safety and durability of finished tyres.
• Wire Producers and Suppliers: Enables consistency in quality control, with standardized methods for in-house and customer-facing test reports.
• Rubber Product Reinforcement: Beyond tyres, the standard’s test methods can be applied by agreement to steel filaments reinforcing hoses, seals, belts, and similar products.
• Quality Assurance and Compliance: Serves as a reference for verifying product conformity in procurement processes and during audits.
• Research and Product Development: Provides a reliable framework for developing new bead wire products with traceable, reproducible test results.

Practical scenarios include:

• Verifying mechanical strength of bead wire batches.
• Assessing the uniformity of bronze coatings for corrosion resistance.
• Ensuring compliance with tire manufacturer requirements.
• Streamlining cross-border trade through harmonized test protocols.

Related Standards

Several related standards form an integrated framework for bead wire and metallic wire testing:

• ISO 7800:2012 – Metallic materials - Wire - Simple torsion test: Describes torsion testing, referenced for bead wire.
• ISO 16650:2025 – Bead wire: Another key ISO standard on bead wire, complementing ISO/FDIS 25408-1.
• General ISO test method standards for tensile strength, elongation, and coating thickness may also apply, depending on product and market requirements.

Conclusion

ISO/FDIS 25408-1:2026 sets forth comprehensive, internationally recognized requirements and procedures for testing round steel bead wires in tyre and rubber reinforcement applications. Adhering to this standard ensures product quality, supports regulatory compliance, and fosters global supply chain efficiency. By referencing and applying these methods, companies can guarantee consistent bead wire performance, reduce risk, and enhance product reputation across the tyre and rubber industries.

Keywords: ISO 25408-1, bead wire testing, tyre reinforcement, steel wire standard, mechanical properties, chemical analysis, coating analysis, wire tensile testing, wire torsion test, international standards for bead wire.

FINAL DRAFT
International
Standard
ISO/TC 17/SC 17
Testing method for bead wire —
Secretariat: SAC
Part 1:
Voting begins on:
2026-08-26
General requirements
Voting terminates on:
Méthode d'essai pour les fils de tringle —
2026-10-21
Partie 1: Exigences générales
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 17/SC 17
Testing method for bead wire —
Secretariat: SAC
Part 1:
Voting begins on:
General requirements
Voting terminates on:
Méthode d'essai pour les fils de tringle —
Partie 1: Exigences générales
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ii
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Diameter . 2
4.1 Measuring with micrometre .2
4.1.1 Principle .2
4.1.2 Apparatus .2
4.1.3 Test procedure.3
4.1.4 Calculations and report .3
4.2 Non contact methods — Laser .4
5 Maximum force, total elongation at fracture and yield ratio . 4
5.1 Principle .4
5.2 Apparatus .5
5.2.1 Tensile testing machine .5
5.2.2 Grips.5
5.2.3 Extensometer (Optional) .6
5.2.4 Oven (Optional) .6
5.3 Test procedure .6
5.3.1 Sample preparation .6
5.3.2 Test procedure.6
5.4 Calculation .7
5.5 Report .7
5.6 Precision and variance limits .7
6 Bend . 8
6.1 Principle .8
6.2 Apparatus .8
6.3 Test procedure .9
6.3.1 Sample preparation .9
6.3.2 Test procedure.9
6.4 Report .10
6.5 Precision and variance .11
7 Torsions .11
7.1 Principle .11
7.2 Apparatus .11
7.2.1 Torsion tester .11
7.3 Test procedure . 12
7.3.1 Sample preparation . 12
7.3.2 Test settings. 12
7.3.3 Test procedure. 12
7.4 Report . 12
7.5 Precision and variance . 12
8 Residual torsions bead wire .13
8.1 Principle . 13
8.2 Apparatus . 13
8.3 Test procedure . 13
8.4 Report .14
9 Straightness . 14
9.1 Principle .14
9.2 Test option 1 . 15
9.2.1 Apparatus . 15
9.2.2 Test procedure (option 1) . 15

iii
9.3 Test option 2 . 15
9.3.1 Apparatus . 15
9.3.2 Test procedure (option 2) . 15
9.4 Report .16
10 Tip rise and S-shape of bead wire .16
10.1 Test procedures .16
10.2 Report .17
10.3 S-shape of bead wire .17
10.4 Report .17
11 Mass and composition of bronze coating by X-ray fluorescence spectroscopy . 17
11.1 Principle .17
11.2 Apparatus .17
11.3 Test procedure .18
11.3.1 Preparation of test samples .18
11.3.2 Procedure .19
11.4 Expression of results .19
11.5 Test report .19
Bibliography .20

iv
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 17, Steel wire rod
and wire products.
A list of all parts in the ISO 25408 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
FINAL DRAFT International Standard ISO/FDIS 25408-1:2026(en)
Testing method for bead wire —
Part 1:
General requirements
1 Scope
This document specifies test methods of round steel bead wires (BW) which are used for tyre reinforcement.
Test methods on mechanical properties and chemical properties (coating analysis) are included.
By agreement, these test methods can be applied to similar single filaments used for reinforcing other
rubber products.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 7800:2012, Metallic materials — Wire — Simple torsion test
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
diameter
average of maximum and minimum values in multiple transversal measurements on the same section of the
specimen.
3.2
out-of-roundness
absolute value of the arithmetic difference between the maximum and minimum diameter measured in the
same transverse cross-section perpendicular to the wire axis
3.3
maximum force
F
m
highest load that the material withstands when subjected to the static tensile test is represented, expressed
in newtons
Note 1 to entry: Maximum force is not equal to breaking load.

3.4
total elongation at fracture
percentage of the ratio of the arithmetic value of subtracting the original gauge length from the total length
of the specimen at the time of fracture to the original gauge length
[SOURCE: ISO 16650:2025,3.4]
Note 1 to entry: Total elongation at fracture is not equal to Total elongation at maximum force.
3.5
yield strength
highest stress to which a material can be subjected before plastic deformation occurs
3.6
yield ratio
force ratio at 0,2 % elongation offset to maximum force, expressed in %
3.7
tensile strength
R
m
maximum force, F , that the test piece withstands divided by the original cross-sectional area, expressed in
m
N/mm
3.8
arc height
expression of short distance for straightness of bead wire
Note 1 to entry: It is a more practical and easier way of working to determine the performance of straightness of bead
wire
3.9
straightness
maximum bow height (or curvature) measured over a given gauge length of the wire
4 Diameter
4.1 Measuring with micrometre
4.1.1 Principle
Hold the sample between two parallel circular faced anvils of a micrometre. Close the movable anvil
gradually and gently until it is in contact with the specimen. Read the value on the micrometre.
4.1.2 Apparatus
4.1.2.1 Micrometre
a) A precision cylindrical outside micrometre with non-rotating spindle type with a resolution of 0,001 mm
shall be used (see Figure 1).
b) The micrometre shall have a circular spindle of ⌀6,35 mm in diameter.
c) Measuring range of the micrometre is from 0 mm to 25 mm.
d) Measuring force range of the micrometre is <10 N.

Figure 1 — Micrometre illustration
4.1.3 Test procedure
4.1.3.1 Sample preparation
a) Cut a sample at length (about 10 cm to 15 cm).
b) A right-angle bend on the wire is to be applied to assist in rotating the wire between measurements.
c) The measured area of the wire shall be as straight as possible.
d) The wire surface shall be clean. Dirt and lubricant residues shall be removed with a clean tissue.
4.1.3.2 Zero-setting of the micrometre
a) Check the zero position of the micrometre and ensure that the numerical value displayed is 0,000 with
closed anvils for electronic micrometre, for a mechanical micrometre, the zero graduation line of the
fixed sleeve shall be aligned.
b) If reset action is needed, both anvil faces shall always be cleaned with a clean paper prior to the reset
action.
c) This ‘zero-setting’ procedure shall to be done before each test series.
4.1.3.3 Method of measuring
a) The movable anvil is closed until it is in contact with the specimen. Closing speed shall be controlled
until three clicks can be heard. The closing speed shall be controlled to avoid too high closing pressure.
b) Measure at least three values at the one section. Record the maximum as d and minimum as d or
1 2
measure two values in two perpendicular directions at the same cross-section, and record two values
as d and d .
3 4
4.1.4 Calculations and report
4.1.4.1 Method for diameter
Determine the wire diameter by calculating the arithmetic mean
...

ISO/TC 17/SC 17/WG 22
Secretariat: SAC
Date: 2026-06-2908-12
Testing method for bead wire — —
Part 1:
General requirements
Méthode d'essai pour les fils de tringle —
Partie 1: Exigences générales
FDIS stage
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents
Foreword . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Diameter . 2
4.1 Measuring with micrometre . 2
4.2 Non contact methods — Laser . 4
5 Maximum force, total elongation at fracture and yield ratio . 5
5.1 Principle . 5
5.2 Apparatus . 7
5.3 Test procedure . 8
5.4 Calculation . 9
5.5 Report . 9
5.6 Precision and variance limits . 9
6 Bend . 10
6.1 Principle . 10
6.2 Apparatus . 10
6.3 Test procedure . 12
6.4 Report . 13
6.5 Precision and variance. 13
7 Torsions. 14
7.1 Principle . 14
7.2 Apparatus . 14
7.3 Test procedure . 14
7.4 Report . 15
7.5 Precision and variance. 16
8 Residual torsions bead wire . 16
8.1 Principle . 16
8.2 Apparatus . 16
8.3 Test procedure . 16
8.4 Report . 19
9 Straightness . 19
9.1 Principle . 19
9.2 Test option 1 . 19
9.3 Test option 2 . 20
9.4 Report . 21
10 Tip rise and S-shape of bead wire . 21
10.1 Test procedures . 21
10.2 Report . 22
10.3 S-shape of bead wire . 22
10.4 Report . 23
11 Mass and composition of bronze coating by X-ray fluorescence spectroscopy . 23
11.1 Principle . 23
11.2 Apparatus . 24
11.3 Test procedure . 25
11.4 Expression of results . 25
11.5 Test report . 25
iii
Bibliography . 26

iv
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 document 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).
Field Code Changed
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
Field Code Changed
This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 17, Steel wire rod
and wire products.
A list of all parts in the ISO 25408 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
Field Code Changed
v
Testing method for bead wire – —
Part 1:
General requirements
1 Scope
This document specifies test methods of round steel bead wires (BW) which are used for tyre reinforcement.
Test methods on mechanical properties and chemical properties (coating analysis) are included.
By agreement, these test methods maycan be applied to similar single filaments used for reinforcing other
rubber products.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 7800:2012, Metallic materials — Wire — Simple torsion test
ISO 16650:2025, Bead wire
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/
3.1 3.1
diameter
average of maximum and minimum values in multiple transversal measurements on the same section of the
specimen.
3.2 3.2
out-of-roundness
absolute value of the arithmetic difference between the maximum and minimum diameter measured in the
same transverse cross-section perpendicular to the wire axis
3.3 3.3
maximum force
F
m
highest load that the material withstands when subjected to the static tensile test is represented, expressed in
newtons
Note 1 to entry: Maximum force is not equal to breaking load.
3.4 3.4
total elongation at fracture
percentage of the ratio of the arithmetic value of subtracting the original gauge length from the total length of
the specimen at the time of fracture to the original gauge length
[SOURCE: ISO 16650:2025,3.4]
Note 1 to entry: Total elongation at fracture is not equal to Total elongation at maximum force.
3.5 3.5
yield strength
highest stress to which a material can be subjected before plastic deformation occurs
3.6 3.6
yield ratio
force ratio at 0,2 % elongation offset to maximum force, expressed in %
3.7 3.7
tensile strength
R
m
maximum force, Fm, that the test piece withstands divided by the original cross-sectional area, expressed in
N/mm
3.8 3.8
arc height
expression of short distance for straightness of bead wire
Note 1 to entry: It is a more practical and easier way of working to determine the performance of straightness of bead
wire
3.9 3.9
straightness
maximum bow height (or curvature) measured over a given gauge length of the wire
4 Diameter
4.1 Measuring with micrometre
4.1.1 Principle
Hold the sample between two parallel circular faced anvils of a micrometre. Close the movable anvil gradually
and gently until it is in contact with the specimen. Read the value on the micrometre.
4.1.2 Apparatus
4.1.2.1 4.1.2.1 Micrometre
a) a) A precision cylindrical outside micrometre with non-rotating spindle type with a resolution of
0,001 mm shall be used (see Figure 1Figure 1).).
b) b) The micrometre shall have a circular spindle of ⌀6,35 mm in diameter.
c) c) Measuring range of the micrometre is from 0 mm to 25 mm.
d) d) Measuring force range of the micrometre is <10 N.
Figure 1 — Micrometre illustration
4.1.3 Test procedure
4.1.3.1 Sample preparation
a) a) Cut a sample at length (about 10 cm to 15 cm).
b) b) A right-angle bend on the wire is to be applied to assist in rotating the wire between
measurements.
c) c) The measured area of the wire shall be as straight as possible.
d) d) The wire surface shall be clean. Dirt and lubricant residues shall be removed with a clean tissue.
4.1.3.2 Zero-setting of the micrometre
a) a) Check the zero position of the micrometre and ensure that the numerical value displayed is
0,000 with closed anvils for electronic micrometre, for a mechanical micrometre, the zero graduation line
of the fixed sleeve shall be aligned.
b) b) If reset action is needed, both anvil faces shall always be cleaned with a clean paper prior to
the reset action.
c) c) This ‘zero-setting’ procedure shall to be done before each test series.
4.1.3.3 Method of measuring
a) a) The movable anvil is closed until it is in contact with the specimen. Closing speed shall be
controlled until three clicks can be heard. The closing speed shall be controlled to avoid too high closing
pressure.
b) b) Measure at least three values at the one section. Record the maximum as d and minimum as
d2 or measure two values in two perpendicular directions at the same cross-section, and record two values
as d and d .
3 4
4.1.4 Calculations and report
4.1.4.1 Method for diameter
Determine the wire diameter by calculating the arithmetic mean (AVG) of maximum and minimum with
Formula (1)Formula (1)::
d =( = (d + d )/2 (1)
0 1 2
where
d is the average diameter, expressed in millimetres (mm);
d is the maximum diameter, expressed in millimetres (mm);
d2 is the minimum diameter, expressed in millimetres (mm).
or determine the wire diameter by calculating the arithmetic average of two measured values with
Formula (2)Formula (2)
d = (d + d )/2 (2)
0 3 4
where
d0 is the average diameter, expressed in millimetres (mm);
d3 is one diameter measured in perpendicular directions, expressed in millimetres (mm);
d4 is the other diameter measured in perpendicular directions, expressed in millimetres (mm)
4.1.4.2 Method for out-of-roundness
Determine the ‘out-of-roundness’ by calculating the difference of the two readings with
Formula (3)Formula (3).
O= d – d (3)
1 2
where
O is the out-of-roundness or ovality of wire, expressed in millimetres (mm);
d is the maximum diameter, expressed in millimetres (mm);
d2 is the minimum diameter, expressed in millimetres (mm).
4.2 Non contact methods –— Laser
a) a) A minimum resolution of 0,001 mm is required.
b) b) The sample shall be cleaned prior to the test.
c) c) During the measurement, the sample shall be perpendicular to the direction in which the laser
is emitted.
d) d) The sample shall be rotatable during testing to have multiple measurements to calculate the
average diameter. The out-of-roundness or non-contact measuring device shall be able to test in multiple
angles (Min 4) to take average diameter and roundness.
NOTE Rotating sample or working with multiple angles laser are all acceptable.
5 Maximum force, total elongation at fracture and yield ratio
5.1 Principle
Both ends of a test sample are clamped under a defined pretension in a tensile testing machine; increasing
load under a constant rate of extension is applied until the specimen breaks. The change in force is measured
versus the increase in separation of the specimen clamps to form a force-extension curve. The maximum force
is measured, total elongation at fracture and yield ratio are calculated (see Figure 2Figure 2).).
NOTE The auto-calculated Young’s modulus is taken to form modulus line for calculating the R . proof of strength
P0 ,2
or yield strength.
Key
F force
0 zero point curve
e percentage extension
Fm maximum force
Rp proof strength, plastic extension
ep specified percentage plastic extension
0 zero point                      mE slope of the elastic part of the stress-percentage extension curve
e   percentage extension            a fracture
Fm  maximum force                 At percentage total extension at fracture
Rp  proof strength, plastic extension

Figure 2 — Tensile stress-strain curve
5.2 Apparatus
5.2.1 Tensile testing machine
a) a) For the constant rate of extension (CRE) tensile testing machine, the measured force required
to fracture the wire shall not exceed 90 % of the selected force measurement range. The device is
equipped with a load and extension recorder, digital read-out, automated data logger or computer
controlled tensile test machine.
b) b) The cross-head speed: maximum speed ≥ 150 mm/min. (≠ test speed)
c) c) The machine accuracy Class 0,5 = Load weighing accuracy: +/-± 0,5 %
d) d) The load cell capacity depends on the type and characteristics of the wire.
e) e) The structure of the machine and gripping systems shall be able to handle the axial force.
f) f) The specifications and methods of calibration and verification for tensile testing machines shall
conform to appropriate standards.
5.2.2 Grips
Grip types shall be selected according to the wire dimensions and characteristics and within range of the load
cell. They may be wedge grip type or action screw type or pneumatic action type with suitable jaw faces
(serrated or grooved) to avoid failure of specimen at gripping point and avoid slippage of specimen within the
jaws (grips).
5.2.3 Extensometer (Optional)
a) a) Contact or non-contact extensometers.
b) b) Resolution of 0,001 % of the gauge length.
c) c) Gauge length: length = 200 mm (≠ test length) or according to customer requirements.
d) d) Extensometer accuracy Class 0,5
— — Contact extensometer with sensor and contact arms
— — Non-contact extensometer
e) e) Video extensometer
f) f) Laser extensometer
g) g) Light extensometer
5.2.4 Oven (Optional)
— — Specifications : Capable of reaching temperatures up to 200 °C.
— — Built-in timer is preferred.
...