Cobalt-Chrome Alloy Stellite 12 vs Stellite 21
Cobalt-Chrome Alloy · grade comparison
Cobalt-Chrome Alloy Stellite 12 and Stellite 21 are both cobalt-chrome alloy grades. Stellite 12 is the stronger of the two: yield strength 650 MPa (94.3 ksi) against 495 MPa (71.8 ksi) for Stellite 21, about 31% 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 Stellite 12, and Stellite 12 is harder (48 HRC vs 32 HRC). Stellite 21 is lighter (8.33 g/cm³ vs 8.6 g/cm³ for Stellite 12) and Stellite 21 is stiffer (248 GPa vs 230 GPa). On the shop floor, Stellite 21 welds better (good vs fair) and Stellite 12 sits in a lower cost tier (high, $$$$) than Stellite 21 (specialty, $$$$$).
Stellite 12Choose 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.
Stellite 12 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
Poisson's Ratio
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Compressive Strength
Shear Strength
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Rockwell C
Hardness, Vickers
Reduction in Area
Hardness, Brinell
Same in both: Fatigue Strength (Endurance Limit) 240 MPa34.8 ksi
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)
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Latent Heat of Fusion 270 J/g116 BTU/lb
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 %)
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Polishability
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 | Stellite 12 | Stellite 21 |
|---|---|---|
| Default condition | — | As Cast |
| Relative cost | $$$$ High | $$$$$ Specialty |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Stellite 12 vs Stellite 21 — frequently asked
Is Stellite 12 stronger than Stellite 21?
Yes. Stellite 12 has a typical yield strength of 650 MPa (94.3 ksi) against 495 MPa (71.8 ksi) for Stellite 21 — about 31% more. Tensile strength is 830 MPa (120 ksi) vs 710 MPa (103 ksi).
Which is cheaper, Stellite 12 or Stellite 21?
Stellite 12 is the lower-cost material: it sits in the high tier ($$$$) while Stellite 21 is specialty ($$$$$). 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 12 or Stellite 21?
Stellite 21. Its machinability rates poor (15/100) against not recommended (8/100) for Stellite 12; for welding the order is Stellite 21 first (good, 55/100) then Stellite 12 (fair, 35/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in Stellite 12 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.