Cobalt-Chrome Alloy ERCoCr-C vs Stellite 21
Cobalt-Chrome Alloy · grade comparison
Cobalt-Chrome Alloy ERCoCr-C and Stellite 21 are both cobalt-chrome alloy grades. ERCoCr-C is the stronger of the two: yield strength 600 MPa (87 ksi) against 495 MPa (71.8 ksi) for Stellite 21, about 21% more. In exchange, Stellite 21 is the more ductile: elongation 9% versus 0.5% for ERCoCr-C, and ERCoCr-C is harder (520 HB vs 300 HB). Stellite 21 is lighter (8.33 g/cm³ vs 8.68 g/cm³ for ERCoCr-C). On the shop floor, Stellite 21 machines more easily (poor vs not recommended), Stellite 21 welds better (good vs fair), and ERCoCr-C sits in a lower cost tier (high, $$$$) than Stellite 21 (specialty, $$$$$).
ERCoCr-CChoose it when strength drives the design, or when cost is the deciding factor.
Stellite 21Choose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
ERCoCr-C vs Stellite 21: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all cobalt-chrome alloy grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all cobalt-chrome alloy grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Bulk Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Same in both: Poisson's Ratio 0.3
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Liquidus Temperature
Thermal
How each material carries heat and how hot it can run.
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Latent Heat of Fusion
Same in both: Thermal Conductivity 14.8 W/m·K8.6 BTU/hr·ft·°F · Specific Heat Capacity 423 J/kg·K0.1 BTU/lb·°F · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Galvanic Potential (seawater, vs SCE)
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Carbon (primary production)
Typical Recycled Content
Embodied Water
Same in both: Embodied Energy (primary production) 145 MJ/kg62,339 BTU/lb
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Same in both: Thermal Shock Resistance Index 3
Strength versus weight
Yield strength against density for every cobalt-chrome alloy grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | ERCoCr-C | Stellite 21 |
|---|---|---|
| Default condition | — | As Cast |
| Relative cost | $$$$ High | $$$$$ Specialty |
| Min. machined wall | — | — |
| Best machined surface | — | — |
ERCoCr-C vs Stellite 21 — frequently asked
Is ERCoCr-C stronger than Stellite 21?
Yes. ERCoCr-C has a typical yield strength of 600 MPa (87 ksi) against 495 MPa (71.8 ksi) for Stellite 21 — about 21% more. Tensile strength is 620 MPa (89.9 ksi) vs 710 MPa (103 ksi).
Which is cheaper, ERCoCr-C or Stellite 21?
ERCoCr-C is the lower-cost material: it sits in the high tier ($$$$) while Stellite 21 is specialty ($$$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, ERCoCr-C or Stellite 21?
Stellite 21. Its machinability rates poor (15/100) against not recommended (5/100) for ERCoCr-C; for welding the order is Stellite 21 first (good, 55/100) then ERCoCr-C (fair, 35/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in ERCoCr-C and Stellite 21 side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.