ISO 8458-2:2026

International
Standard
ISO 8458-2
Third edition
Steel wire for mechanical springs —
2026-01
Part 2:
Patented cold-drawn non-alloy steel
wire
Fils en acier pour ressorts mécaniques —
Partie 2: Fils en acier non allié, patentés, tréfilés à froid
Reference number
© ISO 2026
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Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Classification and designation . 1
5 Dimensions and supply conditions . 2
5.1 Dimensional tolerances .2
5.2 Welds .2
5.3 Cast of the wire .2
5.4 Straightness of cut lengths .2
6 Requirements . 3
6.1 Material .3
6.1.1 General .3
6.1.2 Chemical composition .3
6.2 Coating and surface finish .3
6.3 Surface quality .4
6.4 Mechanical properties .4
6.5 Technological properties .7
6.5.1 Wrapping test .7
6.5.2 Torsion test .7
6.5.3 Bend test .8
6.5.4 Coiling test .8
7 Inspection and testing . 8
7.1 Test methods and other requirements .8
7.2 Extent of testing .8
Bibliography .10

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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
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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.
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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.
This third edition cancels and replaces the second edition (ISO 8458-2:2002), of which it constitutes a minor
revision.
The changes are as follows:
— the normative references have been updated;
— the structure of the document has been updated in accordance with the latest ISO/IEC Directives, Part 2.
A list of all parts in the ISO 8458 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.

iv
International Standard ISO 8458-2:2026(en)
Steel wire for mechanical springs —
Part 2:
Patented cold-drawn non-alloy steel wire
1 Scope
This document specifies requirements for cold-drawn non-alloy steel wire for the manufacture of mechanical
springs for static duty and dynamic duty applications, in accordance with the general requirements of
ISO 8458-1.
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 8458-1, Steel wire for mechanical springs — Part 1: General requirements
ISO 16120-1, Non-alloy steel wire rod for conversion to wire — Part 1: General requirements
ISO 16120-2, Non-alloy steel wire rod for conversion to wire — Part 2: Specific requirements for general purpose
wire rod
ISO 16120-4, Non-alloy steel wire rod for conversion to wire — Part 4: Specific requirements for wire rod for
special applications
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8458-1 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/
4 Classification and designation
The wire diameter ranges and tensile strength grades normally available for static duty and dynamic duty
are shown in Table 1.
Table 1 — Tensile strength grades and diameter range
a
Tensile strength Static duty Diameter range Dynamic duty Diameter range
Low tensile strength SL 1-10 — —
Medium tensile strength SM 0,30-20,00 DM 0,08-20,00
High tensile strength SH 0,30-20,00 DH 0,05-20,00
a
For specific applications, other tensile strength requirements may be agreed.

5 Dimensions and supply conditions
5.1 Dimensional tolerances
The dimensional tolerances on wire diameters shall be in accordance with ISO 8458-1.
5.2 Welds
The wire of a unit coil shall consist of one single length of wire originating from only one heat.
For coiled and cut lengths of wire, welds prior to the last patenting operation are allowed. All other welds
shall be removed or, if so agreed, properly marked.
5.3 Cast of the wire
5.3.1 The wire shall be uniformly cast.
5.3.2 By agreement, for sizes up to 5 mm, the cast requirements may be considered as being fulfilled if the
following statement is satisfied.
An individual ring taken from the coil and freely hung on a hook may show an axial displacement, f, at the
ends of the ring (see Figure 1).
This displacement, f, shall not exceed a value given by the following inequality [see Formula (1)]:
fD02,/ 4 d (1)

where
f is the axial displacement in millimetres;
D is the diameter of a free ring in millimetres;
d is the nominal diameter of the wire in millimetres.
Figure 1 — Cast of wire
5.4 Straightness of cut lengths
For the straightness of cut lengths, the following requirements apply.
For 500 mm test lengths – 0,5 mm maximum deviation from straightness.

For 1 000 mm test lengths – 2 mm maximum deviation from straightness.
1 000 mm test lengths are recommended for wire diameter above 6 mm and 500 mm test lengths for those
below.
6 Requirements
6.1 Material
6.1.1 General
Spring wire shall be made from steel in accordance with ISO 16120-1.
For grades SL, SM and SH the steel shall be in accordance with ISO 16120-2.
For grades DM and DH, the steel shall comply with ISO 16120-4.
6.1.2 Chemical composition
The steel is characterized by the heat analysis, which shall be in accordance with the values of Table 2. The
permissible deviation of the product analysis from the heat analysis shall be in accordance with ISO 16120-2
or ISO 16120-4.
Table 2
...