Overview
EN ISO 5832-6:2022 - "Implants for surgery - Metallic materials - Part 6: Wrought cobalt‑nickel‑chromium‑molybdenum alloy" specifies the required chemical composition, microstructure, tensile properties and corresponding test methods for wrought Co–Ni–Cr–Mo alloys used as raw material in the manufacture of surgical implants. Published by CEN/ISO, this standard applies to the base material (not finished devices) and is part of the ISO 5832 series for implant metallic materials.
Key topics and technical requirements
- Chemical composition (heat analysis): the alloy composition limits include, for example:
- Nickel: 33.0–37.0%
- Chromium: 19.0–21.0%
- Molybdenum: 9.0–10.5%
- Boron: ≤ 0.015% and limits for Fe, Ti, Mn, Si, C, P, S; Cobalt as balance.
- Microstructure
- Microstructure must be uniform.
- Grain size in the annealed condition shall be not coarser than grain size No. 4 (per ISO 643).
- Tensile properties (tested per ISO 6892‑1): specified minimum values by condition:
- Annealed: Tensile strength Rm ≥ 793 MPa, Proof/Yield Rp0.2 ≥ 300 MPa, Elongation A ≥ 50%
- Medium hard: Rm ≥ 1 000 MPa, Rp0.2 ≥ 655 MPa, A ≥ 20%
- Hard: Rm ≥ 1 207 MPa, Rp0.2 ≥ 1 000 MPa, A ≥ 10%
- Note: tensile properties can be altered by cold‑working and ageing; tensile results from finished product samples may not reflect these raw‑material values.
- Test methods & conformity
- Chemical analysis, grain size (ISO 643) and tensile testing (ISO 6892‑1) are referenced.
- Retest and failure handling procedures are defined for conformity assessment.
Applications and practical value
- Material specification for manufacturers of orthopaedic and trauma implants, dental implants, and other non‑active surgical implants where Co–Ni–Cr–Mo alloys are chosen for strength and corrosion resistance.
- Used by material suppliers, medical device OEMs, quality/acceptance laboratories, and regulatory/standards teams to:
- Verify raw‑material compliance before device fabrication.
- Define procurement specifications and supplier contracts.
- Support regulatory submissions and technical documentation.
Who should use this standard
- Implant manufacturers, metallurgists, procurement and quality engineers, test laboratories, and regulatory compliance personnel involved with metallic implant materials.
Related standards
- ISO 5832 series (other metallic implant materials)
- ISO 643 - Micrographic determination of apparent grain size
- ISO 6892‑1 - Tensile testing of metallic materials
This standard provides authoritative, testable requirements for wrought Co–Ni–Cr–Mo implant alloy supply and acceptance, helping ensure material consistency, safety, and traceability in surgical implant manufacturing.
