Overview
EN ISO 5832-7:2024 specifies the required characteristics and test methods for forgeable and cold-formed cobalt-chromium-nickel-molybdenum-iron (Co-Cr-Ni-Mo-Fe) alloy intended for use in the manufacture of surgical implants. The standard addresses raw material composition, microstructure, inclusion limits and mechanical properties, and references recognized test methods to verify conformity. Note that mechanical properties of finished devices can differ from those of raw material samples.
Why this standard matters
- Ensures consistent alloy composition and microstructure for implant manufacturing
- Defines mechanical property minima for typical conditions (annealed, hot-worked, cold-worked)
- Provides harmonized test methods to support regulatory compliance and quality control
Key Topics
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Chemical composition
- The alloy composition is specified by mass fractions. Typical limits include: cobalt 39.0 to 42.0%, chromium 18.5 to 21.5%, nickel 14.0 to 18.0%, molybdenum 6.5 to 8.0%, with iron as balance. Controlled maximums apply for elements such as carbon, silicon, phosphorus, sulfur and beryllium.
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Microstructure
- The standard requires a uniform microstructure with grain size no coarser than grain size No. 5.
- Non-metallic inclusion content is limited; thin inclusions are bounded per type (sulfides, aluminates, silicates, globular oxides) and thick inclusions are not permitted.
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Mechanical properties
- Minimum tensile strength and proof/yield strength and elongation are specified for conditions including annealed, hot-worked, 30% cold-worked and spring temper. Examples: annealed condition minimum tensile strength 950 MPa and minimum elongation 65% (see standard for full table).
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Test methods
- Test procedures include ISO 643 (grain size), ISO 4967 (inclusion content) and ISO 6892-1 (tensile testing at room temperature), together with recognized analytical procedures for chemical analysis.
Applications
This alloy and the standard are intended for manufacturers of surgical implants and material suppliers involved in:
- Orthopaedic and trauma implant components
- Dental implant frameworks
- Any non-active surgical implant applications where forgeable or cold-formed Co-Cr-Ni-Mo-Fe is appropriate
Following EN ISO 5832-7:2024 supports product conformity, traceable material verification, and reproducible mechanical behavior in downstream device fabrication.
Related Standards
- ISO 643: Micrographic determination of apparent grain size
- ISO 4967: Determination of non-metallic inclusions
- ISO 6892-1: Tensile testing of metallic materials at room temperature
- Other parts of the ISO 5832 series covering alternative implant metals and alloys
For implementation, manufacturers should consult the full EN ISO 5832-7:2024 text and coordinate testing and certification with their national standards body or conformity assessment authority.
