Cobalt-Chrome Alloy Stellite 6 vs Ultimet
Cobalt-Chrome Alloy · grade comparison
Cobalt-Chrome Alloy Stellite 6 and Ultimet are both cobalt-chrome alloy grades. Stellite 6 is the stronger of the two: yield strength 541 MPa (78.5 ksi) against 490 MPa (71.1 ksi) for Ultimet, about 10% more. In exchange, Ultimet is the more ductile: elongation 39% versus 1% for Stellite 6, and Stellite 6 is harder (40 HRC vs 28 HRC). Ultimet runs hotter in service (900°C vs 800°C continuous) and Stellite 6 conducts heat better (14.8 W/m·K vs 11 W/m·K). On the shop floor, Ultimet machines more easily (poor vs not recommended), Ultimet welds better (very good vs good), and Ultimet sits in a lower cost tier (high, $$$$) than Stellite 6 (specialty, $$$$$).
Stellite 6Choose it when strength drives the design.
UltimetChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
Stellite 6 vs Ultimet: 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
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Rockwell C
Hardness, Vickers
Reduction in Area
Shear Strength
Hardness, Brinell
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)
Max Service Temperature (continuous)
Latent Heat of Fusion
Same in both: Min Service Temperature -196°C-321 °F
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
Same in both: Polishability 85 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 30%
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 4
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 6 | Ultimet |
|---|---|---|
| Default condition | As Cast | — |
| Relative cost | $$$$$ Specialty | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Stellite 6 vs Ultimet — frequently asked
Is Stellite 6 stronger than Ultimet?
Yes. Stellite 6 has a typical yield strength of 541 MPa (78.5 ksi) against 490 MPa (71.1 ksi) for Ultimet — about 10% more. Tensile strength is 834 MPa (121 ksi) vs 1,000 MPa (145 ksi).
Which is cheaper, Stellite 6 or Ultimet?
Ultimet is the lower-cost material: it sits in the high tier ($$$$) while Stellite 6 is specialty ($$$$$). 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 6 or Ultimet?
Ultimet. Its machinability rates poor (18/100) against not recommended (8/100) for Stellite 6; for welding the order is Ultimet first (very good, 75/100) then Stellite 6 (good, 55/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in Stellite 6 and Ultimet 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.