ISO 6931-1:2016

Overview

ISO 6931-1:2016 - "Stainless steels for springs - Part 1: Wire" defines the stainless steel grades, delivery conditions and test requirements for cold-drawn, circular-section spring wire (nominal diameter up to 10.00 mm) used to make springs and spring parts exposed to corrosive environments and mildly elevated temperatures. The standard also allows ordering wires between 10.00 mm and 15.00 mm by agreement and references general delivery rules in ISO 404.

Key topics and technical requirements

• Material grades and chemistry: Specifies commonly used austenitic, duplex and precipitation‑hardening stainless steels for spring wire (examples include X10CrNi18‑8 / 4310‑301‑00‑I, X5CrNi18‑10 / 4301‑304‑00‑I, X2CrNiMoN22‑5‑3 / 4462‑318‑03‑I). Chemical composition requirements are provided as cast-analysis limits.
• Mechanical properties: Defines tensile strength levels in the as‑drawn condition, including normal (NS) and high (HS) tensile-strength levels. Mechanical property ranges are presented by nominal diameter groups.
• Forms of supply and surface finish: Wire can be supplied in coils, on spools/coreless spools, carriers or as straightened and cut lengths. Surface finish options (e.g., uncoated, polished, nickel coated) are to be agreed at order.
• Dimensional and surface requirements: Tolerances for diameter, out‑of‑roundness and cut length classes, plus surface quality, inner soundness and wire cast/helix specifications.
• Testing and inspection: Covers sampling, inspection documents and test methods including chemical analysis, tensile testing, coiling, wrapping, simple bend and reverse‑torsion tests, and wire-cast assessment.
• Purchaser information: Lists required data for enquiries/orders - grade, tensile level, nominal diameter and tolerance class, surface finish, delivery form and inspection document type.

Practical applications and users

ISO 6931-1 is intended for:

• Spring manufacturers designing corrosion‑resistant springs for valves, pumps, automotive systems, medical devices and general industrial applications.
• Materials engineers and metallurgists specifying spring wire grades and mechanical requirements.
• Procurement and quality teams who require consistent stainless steel spring wire quality, traceability and inspection documentation.
• Test laboratories verifying chemical composition and mechanical performance to international norms.

Adopting ISO 6931-1 ensures predictable corrosion performance, consistent tensile properties and standardized delivery formats for spring wire - reducing risk in production and easing cross-border procurement.

Related standards

• ISO 404 - General technical delivery requirements
• ISO 16143-2 - Stainless steels for general purposes (relevant alternative grades)
• Test & sampling standards referenced: ISO 6892-1, ISO 10474, ISO 14284, ISO 22034 (see ISO 6931-1 for full normative list)

Keywords: ISO 6931-1, stainless steel spring wire, spring steels, tensile strength, corrosion-resistant spring wire, cold-drawn wire, wire diameter, spring manufacturing.