Overview
ISO 5832-12:2019 specifies requirements for two wrought cobalt‑chromium‑molybdenum (CoCrMo) alloys intended for surgical implants. The standard covers chemical composition, microstructure and mechanical properties for wrought bar, rod and wire forms used to produce implant components. It defines two variants: low‑carbon (Alloy 1) and high‑carbon (Alloy 2), and sets test methods to demonstrate conformity.
Key topics and requirements
- Chemical composition: Specified mass fractions include
- Chromium: 26.0–30.0%
- Molybdenum: 5.0–7.0%
- Carbon: Alloy 1 ≤ 0.14%; Alloy 2 = 0.15–0.35%
- Iron: ≤ 0.75%; Mn, Si, Ni: ≤ 1.0% each; N: ≤ 0.25%; Cobalt: balance
- Microstructure: Uniform microstructure required; grain size shall be not coarser than No. 5 (ISO 643).
- Mechanical properties: Minimum tensile and proof/yield values and elongation for typical conditions:
- Annealed: Rm ≥ 897 MPa, Rp0.2 ≥ 517 MPa, A ≥ 20%
- Hot worked: Rm ≥ 1 000 MPa, Rp0.2 ≥ 700 MPa, A ≥ 12%
- Warm worked: Rm ≥ 1 172 MPa, Rp0.2 ≥ 827 MPa, A ≥ 12%
- Testing methods: Chemical analysis by recognized procedures; grain size by ISO 643; tensile testing by ISO 6892‑1. Retest and acceptance rules for failed specimens are defined.
- Important notes: Mechanical properties of finished devices can differ from bar/rod/wire samples; carbide distribution (affected by the alloy’s high carbon content) can be adjusted during manufacturing but the final carbide distribution in devices is outside the scope of this document.
Applications and users
ISO 5832-12:2019 is intended for stakeholders involved in the manufacture, specification, testing and regulation of metallic surgical implants, including:
- Implant manufacturers and component fabricators (bars, rods, wire feedstock)
- Material suppliers and metallurgists specifying CoCrMo alloys
- Test laboratories and quality managers performing conformity testing
- Biomedical engineers and device designers selecting materials for surgical implants
Typical applications include metallic implant components produced from wrought feedstock (orthopaedic and other surgical devices) where controlled chemistry, microstructure and mechanical performance are critical.
Related standards
- Other parts of the ISO 5832 series (metallic materials for implants)
- Test standards referenced: ISO 643 (grain size) and ISO 6892‑1 (tensile testing)
Practical takeaway: Use ISO 5832‑12:2019 to ensure wrought CoCrMo implant feedstock meets defined composition, microstructure and strength requirements and to align testing with recognized ISO methods when qualifying materials for surgical use.
Open preview (PDF)Implants for surgery — Metallic materials — Part 12: Wrought cobalt-chromium-molybdenum alloy