Cobalt-Chrome Alloy Stellite 21 vs Stellite 3
Cobalt-Chrome Alloy · grade comparison
Cobalt-Chrome Alloy Stellite 21 and Stellite 3 are both cobalt-chrome alloy grades. Stellite 3 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 Stellite 3, and Stellite 3 is harder (580 HB vs 300 HB). Stellite 21 is lighter (8.33 g/cm³ vs 8.6 g/cm³ for Stellite 3) and Stellite 21 is stiffer (248 GPa vs 230 GPa). On the shop floor, Stellite 21 machines more easily (poor vs not recommended), Stellite 21 welds better (good vs poor), and Stellite 3 sits in a lower cost tier (high, $$$$) than Stellite 21 (specialty, $$$$$).
Stellite 21Choose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
Stellite 3Choose it when strength drives the design, or when cost is the deciding factor.
Stellite 21 vs Stellite 3: 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 Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Max Service Temperature (continuous)
Min Service Temperature
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
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 %)
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
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 | Stellite 21 | Stellite 3 |
|---|---|---|
| Default condition | As Cast | — |
| Relative cost | $$$$$ Specialty | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Stellite 21 vs Stellite 3 — frequently asked
Is Stellite 3 stronger than Stellite 21?
Yes. Stellite 3 has a typical yield strength of 600 MPa (87 ksi) against 495 MPa (71.8 ksi) for Stellite 21 — about 21% more. Tensile strength is 620 MPa (89.9 ksi) vs 710 MPa (103 ksi).
Which is cheaper, Stellite 21 or Stellite 3?
Stellite 3 is the lower-cost material: it sits in the high tier ($$$$) while Stellite 21 is specialty ($$$$$). 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, Stellite 21 or Stellite 3?
Stellite 21. Its machinability rates poor (15/100) against not recommended (4/100) for Stellite 3; for welding the order is Stellite 21 first (good, 55/100) then Stellite 3 (poor, 20/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in Stellite 21 and Stellite 3 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.