Description
Overview Of CoCrMo
CoCrMo is a cobalt-based alloy renowned for its exceptional wear resistance, corrosion resistance, and biocompatibility. Widely used in biomedical implants, aerospace, and high-temperature industrial applications, it combines the strength of cobalt with chromium and molybdenum to deliver performance in extreme environments. As a powder, CoCrMo is optimized for additive manufacturing (AM) and metal injection molding (MIM), enabling complex, high-precision components.
Powder Chemical Composition(wt,-%)
Typical composition of CoCrMo powder (per ASTM F75 and ISO 5832-12 standards):
| Element | Content (wt%) | Role |
| Cobalt (Co) | 58–65% | Base metal, provides high-temperature strength and toughness |
| Chromium (Cr) | 27–30% | Enhances corrosion/oxidation resistance (forms Cr₂O₃ passive layer) |
| Molybdenum (Mo) | 5–7% | Improves strength, wear resistance, and grain refinement |
| Carbon (C) | ≤0.35% | Forms carbides (e.g., Cr₃C₂) for wear resistance |
| Nickel (Ni) | ≤1.0% | Optional for ductility improvement |
| Iron (Fe) | ≤0.75% | Impurity control |
| Silicon (Si) | ≤1.0% | Deoxidizer and fluidity enhancer |
| Manganese (Mn) | ≤1.0% | Sulfur scavenger |
Physical & Mechanical Properties
Key properties of CoCrMo in as-sintered and heat-treated conditions:
| Property | As-Sintered | Heat-Treated |
| Tensile Strength (MPa) | 800–1000 | 1000–1300 |
| Yield Strength (MPa) | 600–800 | 800–1000 |
| Elongation at Break (%) | 8–15 | 5–10 |
| Hardness (HV) | 300–400 | 400–500 |
| Density (g/cm³) | 8.3–8.5 | 8.3–8.5 |
| Melting Point (°C) | 1350–1450 | 1350–1450 |
| Thermal Conductivity (W/m·K) | 12–15 | 12–15 |
| Corrosion Resistance | Excellent (passive Cr₂O₃ layer) | Maintained under stress |
Comparison With Similar Alloys
| Alloy | Key Advantages | Primary Use |
| CoCrMo | Biocompatibility, wear resistance | Medical implants, aerospace |
| CoCrMoW | Higher thermal stability (W addition) | Extreme-temperature tools |
| Ti-6Al-4V | Lightweight, high strength-to-weight | Aerospace, biomedical |
| 316L Stainless | Cost-effective corrosion resistance | General industrial |
Key Features
Biocompatibility
● Complies with ASTM F75 and ISO 5832-12 for medical implants (e.g., hip/knee replacements, dental prosthetics).
● Low ion release and resistance to bodily fluids.
Wear & Fatigue Resistance
● Ideal for high-stress applications like turbine blades, engine valves, and cutting tools.
● Retains hardness up to 600°C due to carbide formation (Cr₃C₂, MoC).
Additive Manufacturing Compatibility
● Suitable for laser powder bed fusion (LPBF) and electron beam melting (EBM).
● Powder specifications:
Particle size: 15–45 μm (spherical morphology via gas atomization).
Oxygen content: <0.1% (critical for minimizing brittleness).
Post-Processing
● Heat treatment (e.g., hot isostatic pressing, HIP) reduces porosity and enhances mechanical properties.
● Electrochemical polishing achieves surface roughness Ra <0.1 μm for medical devices.
Primary Applications
Medical:
● Orthopedic implants (hip stems, knee joints), dental crowns, and surgical instruments.
Aerospace:
● Turbine blades, fuel nozzles, and high-temperature engine components.
Industrial:
● Wear-resistant coatings, dies, and molds for plastic injection or metal forming.
Energy:
● Valve components in nuclear reactors and oil/gas drilling equipment.
