ASTM F1537 Co-28cr-6mo Alloy Bar
Products Description
The Co-28Cr-6Mo alloy simultaneously offers exceptional wear resistance, corrosion resistance, and non-magnetic properties-qualities that have earned it the title of the "King of Medical Metals." After years of working with this material, our procurement and business teams at Lork Group have come to a definitive conclusion: while it serves as the "gold standard" for materials used in medical artificial joints, the barriers to entry for its hot working and machining are truly formidable.
Co-28Cr-6Mo (UNS R31537/R31538, ASTM F1537, ISO 5832-12) is a forged cobalt-chromium-molybdenum alloy specifically designed for load-bearing orthopedic implants. It neither triggers rejection reactions following implantation surgery nor undergoes corrosion, and it does not interfere with magnetic resonance imaging (MRI) scans. It is precisely this material that is utilized to fabricate the articulating surfaces of artificial hip and knee joints-the very surfaces that are continuously subjected to friction day in and day out. While ordinary stainless steel would fail due to wear after just a few years of such use, this material retains its full functionality even after enduring decades of abrasion.
Its typical applications include: artificial hip femoral heads and stems, knee tibial plateaus, spinal internal fixation rods, dental implants, and surgical instruments.
Standards and Grades Supplied
A client is seeking Co-28Cr-6Mo (Chemical Composition Designation)alloy bars; Lork Group need to confirm the standards and grades that we are able to supply.
| Standard / Grade | Description |
| ASTM F1537 | Core Standard - Forged Cobalt-28 Chromium-6 Molybdenum Alloy Bar |
| UNS R31537 | Low-Carbon Version (Alloy 1) - Enhanced Toughness (Components requiring extensive machining) |
| UNS R31538 | High-Carbon Version (Alloy 2) - Enhanced Wear Resistance (Articular surfaces and components subject to direct wear) |
| UNS R31539 | Dispersion-Strengthened Version (Alloy 3) - Ultra-High Strength (Ultra-High Strength Requirements) |
| ISO 5832-12 | International Standard - Equivalent to F1537 |
| AMS 5844 | Aerospace Version |
Would you prefer low-carbon or high-carbon material? Low-carbon steel is somewhat easier to machine, while high-carbon steel offers superior wear resistance. If you are fabricating articulating surfaces-the kind subject to constant friction-I recommend high-carbon steel; however, if the primary requirement is machining for shaping purposes and the part will not serve as a friction surface, low-carbon steel will suffice.
Chemical Composition
ASTM F1537 Alloy 2 / UNS R31538 (High-Carbon Version)
| Element | Content Range |
| Co | 58.7-68.9% |
| Cr | 26-30% |
| Mo | 5.0-7.0% |
| C | 0.15-0.35% |
| Mn / Si / Ni | ≤1.0% |
Mechanical Properties
| Performance | Metric Value |
| Tensile Strength | 897–1360 MPa |
| Yield Strength | 517–930 MPa |
| Elongation | 12–23% |
| Hardness (HRC) | 25–45 |
| Elastic Modulus | 220 GPa |
| Density | 8.3–8.4 g/cm³ |
Key Highlights:
When reviewing ASTM F1537 cocrmo alloy material test reports, the numerical values serve as indicators of material performance. For instance:
- A wide range of elongation values suggests significant differences across various heat-treatment states-specifically, the annealed state exhibits high ductility, while the processed state offers high strength but is more brittle.
- With an elastic modulus of 220 GPa-higher than that of titanium alloys (~110 GPa)-the material aligns more closely with the modulus-matching requirements for bone tissue.
Supply Condition and Processing
Availability Status
Annealed State: suitable for use as raw stock requiring extensive machining.
Hot-worked condition: Suitable for direct use or minimal processing.
Warm-worked condition: Suitable for finished parts requiring little to no further processing.
Lork Group Processing Recommendations
Cutting Tools: Carbide or CBN (Cubic Boron Nitride)
Cutting Strategy: Low cutting speed + High feed rate + Ample cooling
Avoid: Shallow depths of cut and multiple passes (prone to work hardening)
Welding: Not Recommended; Avoid Welding Whenever Possible.
Related News
We maintain shipment records for ASTM F1537 Co-28Cr-6Mo alloy bars, as well as recommendations for related medical-grade materials, to help you learn more. If you would like to request a quotation, please feel free to contact us.
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