ISO 8458-3:2002

Overview

ISO 8458-3:2002 - "Steel wire for mechanical springs - Part 3: Oil‑hardened and tempered wire" specifies technical and testing requirements for oil‑quenched and tempered carbon and low‑alloy spring wire. It applies to wire intended for manufacture of mechanical springs used in both static duty and dynamic duty applications, and it complements the general requirements of ISO 8458-1.

Key topics and requirements

• Scope and classification

  • Covers oil‑hardened and tempered spring wire grades for static (FD), medium fatigue (TD) and high fatigue/dynamic (VD) service. Variants include CrV and SiCr alloy grades.
  • Diameter ranges typically span about 0.50 mm to 17.00 mm, with lower ranges for TD/VD grades (commonly up to 10 mm for some grades).

• Chemical composition

  • Defines heat analysis limits and permissible product deviations for C, Si, Mn, P, S, Cr, V, Cu (see standard for full tables).

• Mechanical properties

  • Specifies tensile strength and reduction of area ranges by grade and diameter (tables provide precise N/mm or MPa ranges). Tolerance of tensile strength within a coil is limited (e.g., VD: 50 N/mm).

• Surface quality and decarburization

  • Limits for surface discontinuities and permissible decarburization depths are defined by grade and diameter.
  • Eddy‑current inline testing is mandatory for VD grades (optional for TD); non‑metallic inclusion limits for VD are checked per ISO 4967.

• Technological tests

  • Wrapping, torsion, bend and coiling tests are specified with size ranges and acceptance criteria (e.g., torsion test applied for nominal diameters 0.70–6.00 mm using a gauge length of 100 diameters).
  • Test methods, mandatory vs optional tests and sampling plans (production analysis, tensile testing frequency, sample counts) are summarized in the standard.

Applications

• Manufacturing of mechanical springs across industries:
  • Automotive valve springs and high‑fatigue components (VD grades)
  • General-purpose springs for static loads (FD grades)
  • Industrial and precision springs requiring controlled fatigue and surface integrity
• Useful where controlled tensile properties, surface condition and fatigue life are critical.

Who should use this standard

• Spring designers and OEMs, spring‑wire producers, heat‑treatment shops, quality and test laboratories, and procurement/specification engineers who need consistent material and test criteria for oil‑hardened and tempered spring wire.

Related standards

• ISO 8458-1 - General requirements for steel wire for mechanical springs
• ISO 4967 - Non‑metallic inclusion assessment (micrographic method)

Use ISO 8458-3 when you need standardized chemical, mechanical, surface and testing requirements for oil‑quenched and tempered spring wire to ensure reliable spring performance under static and dynamic service.