Cobalt-Chrome Alloy ERCoCr-A vs Stellite 21
Cobalt-Chrome Alloy · grade comparison
Cobalt-Chrome Alloy ERCoCr-A and Stellite 21 are both cobalt-chrome alloy grades. ERCoCr-A is the stronger of the two: yield strength 620 MPa (89.9 ksi) against 495 MPa (71.8 ksi) for Stellite 21, about 25% more; tensile strength follows at 830 MPa (120 ksi) vs 710 MPa (103 ksi). In exchange, Stellite 21 is the more ductile: elongation 9% versus 1% for ERCoCr-A, and ERCoCr-A is harder (390 HB vs 300 HB). Stellite 21 is stiffer (248 GPa vs 210 GPa). On the shop floor, ERCoCr-A sits in a lower cost tier (high, $$$$) than Stellite 21 (specialty, $$$$$).
ERCoCr-AChoose 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.
ERCoCr-A 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
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Reduction in Area
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 Resistivity
Same in both: Electrical Conductivity 2 % IACS
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Formability (cold)
Castability
Polishability
Same in both: Weldability 55 / 100 · Brazeability / Solderability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 25%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
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-A | Stellite 21 |
|---|---|---|
| Default condition | — | As Cast |
| Relative cost | $$$$ High | $$$$$ Specialty |
| Min. machined wall | — | — |
| Best machined surface | — | — |
ERCoCr-A vs Stellite 21 — frequently asked
Is ERCoCr-A stronger than Stellite 21?
Yes. ERCoCr-A has a typical yield strength of 620 MPa (89.9 ksi) against 495 MPa (71.8 ksi) for Stellite 21 — about 25% more. Tensile strength is 830 MPa (120 ksi) vs 710 MPa (103 ksi).
Which is cheaper, ERCoCr-A or Stellite 21?
ERCoCr-A is the lower-cost material: it sits in the high tier ($$$$) while Stellite 21 is specialty ($$$$$). 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-A or Stellite 21?
Stellite 21. Its machinability rates poor (15/100) against not recommended (8/100) for ERCoCr-A.
Ready to make it?
Upload a CAD file and FabDigit prices the part in ERCoCr-A 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.