ISO 8458-3:2026

International
Standard
ISO 8458-3
Third edition
Steel wire for mechanical springs —
2026-01
Part 3:
Oil-hardened and tempered wire
Fils en acier pour ressorts mécaniques —
Partie 3: Fils trempés à l'huile et revenus
Reference number
© ISO 2026
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Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Classification and designation . 1
5 Dimensional tolerances . 2
6 Requirements . 2
6.1 Chemical composition .2
6.2 Surface quality .3
6.3 Non-metallic inclusions .3
6.4 Mechanical properties .3
6.5 Technological properties .3
6.5.1 Wrapping test .3
6.5.2 Torsion test .5
6.5.3 Bend test .6
6.5.4 Coiling test .6
7 Test methods and other requirements . 6

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Foreword
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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 8458-3:2002), 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.

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International Standard ISO 8458-3:2026(en)
Steel wire for mechanical springs —
Part 3:
Oil-hardened and tempered wire
1 Scope
This document specifies requirements for oil-hardened and tempered carbon and low 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 4967, Steel — Determination of content of non-metallic inclusions — Micrographic method using standard
diagrams
ISO 8458-1, Steel wire for mechanical springs — Part 1: General requirements
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 various spring wire grades and the relevant diameters are shown in Table 1.
Table 1 — Spring wire grades and diameter ranges
Tensile strength Static Medium fatigue High fatigue
Low tensile strength FDC TDC VDC
Medium tensile strength FDCrV(A.B) TDCrV(A.B) VDCrV(A.B)
High tensile strength FDSiCr TDSiCr VDSiCr
Diameter range (mm) 0,50 to 17,00 0,50 to 10,00 0,50 to 10,00
FD grade is intended for static applications, required for normal springs.
TD grade is intended for medium fatigue levels.
VD grade is intended for use under severe dynamic duty such as for valve springs.

5 Dimensional tolerances
The permissible dimensional tolerances on wire in coils and cut lengths shall be in accordance with those
specified in ISO 8458-1.
When the required tolerance level is different from those mentioned above, it shall be agreed at the time of
ordering.
6 Requirements
6.1 Chemical composition
The steel is characterized by the heat analysis, which shall be in accordance with the values listed in Table 2.
The permissible deviation of the product analysis from the heat analysis shall be in accordance with Table 3.
Table 2 — Chemical composition, mass fraction
Values in percent
Grade C Si Mn P S Cr V Cu max.
max. max.
FDC 0,60 to 0,75 0,10 to 0,35 0,50 to 1,20 0,030 0,030 — — 0,20
TDC 0,60 to 0,75 0,10 to 0,35 0,50 to 1,20 0,020 0,025 — — 0,12
VDC 0,60 to 0,75 0,15 to 0,30 0,50 to 1,00 0,020 0,025 — — 0,12
FDCrV-A 0,030 0,030 0,20
TDCrV-A 0,47 to 0,55 0,10 to 0,40 0,60 to 1,20 0,025 0,025 0,80 to 1,10 0,15 to 0,25 0,12
VDCrV-A 0,025 0,025 0,12
FDCrV-B 0,030 0,030 0,20
TDCrV-B 0,62 to 0,72 0,15 to 0,30 0,50 to 0,90 0,025 0,025 0,40 to 0,60 0,15 to 0,25 0,12
VDCrV-B 0,025 0,025 0,12
FDSiCr 0,030 0,030 0,20
TDSiCr 0,50 to 0,60 1,20 to 1,60 0,50 to 0,90 0,025 0,025 0,50 to 0,80 — 0,12
VDSiCr 0,025 0,025 0,12
Table 3 — Permissible deviation of the product analysis from the limiting values for the heat
analysis
Chemical element Wire grade Permissible deviation, % by mass
C All ± 0,03
SiCr ±0,05
Si
other grades ±0,03
Mn All ±0,04
P All +0,005
S All +0,005
Cu All +0,02
Cr All ±0,05
V All ±0,02
...