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Cobalt-Chrome Alloy Stellite 21 vs Tribaloy T-800

Cobalt-Chrome Alloy · grade comparison

Cobalt-Chrome Alloy Stellite 21 and Tribaloy T-800 are both cobalt-chrome alloy grades. Stellite 21 is the stronger of the two: tensile strength 710 MPa (103 ksi) against 500 MPa (72.5 ksi) for Tribaloy T-800, about 42% more. Stellite 21 is the more ductile: elongation 9% versus 0.3% for Tribaloy T-800, and Tribaloy T-800 is harder (58 HRC vs 32 HRC). Stellite 21 is lighter (8.33 g/cm³ vs 8.6 g/cm³ for Tribaloy T-800) and Stellite 21 is stiffer (248 GPa vs 225 GPa). On the shop floor, Stellite 21 machines more easily (poor vs not recommended), Stellite 21 welds better (good vs poor), and Tribaloy T-800 sits in a lower cost tier (high, $$$$) than Stellite 21 (specialty, $$$$$).

Stellite 21Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.

Tribaloy T-800Choose it when cost is the deciding factor.

Stellite 21 vs Tribaloy T-800: properties

Stellite 21Tribaloy T-800

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

248 GPa36 Msi
225 GPa32.6 Msi

Shear Modulus

95 GPa13.8 Msi
87 GPa12.6 Msi

Bulk Modulus

200 GPa29 Msi
180 GPa26.1 Msi

Poisson's Ratio

0.3
0.29

Tensile Strength (Ultimate)

710 MPa103 ksi
500 MPa72.5 ksi

Yield Strength (0.2% offset)

495 MPa71.8 ksi
480 MPa69.6 ksi

Elongation at Break

9%
0.3%

Reduction in Area

9%
0%

Compressive Strength

1,250 MPa181 ksi
1,900 MPa276 ksi

Shear Strength

490 MPa71.1 ksi
380 MPa55.1 ksi

Fatigue Strength (Endurance Limit)

240 MPa34.8 ksi
200 MPa29 ksi

Fracture Toughness (K_IC)

50 MPa·√m45.5 ksi·√in
14 MPa·√m12.7 ksi·√in

Charpy V-Notch Impact (RT)

14 J10.3 ft·lbf
2 J1.5 ft·lbf

Hardness, Brinell

300 HB
—

Hardness, Rockwell C

32 HRC
58 HRC

Hardness, Vickers

320 HV
680 HV

Physical

Density and transition temperatures.

Density

8.33 g/cm³0.3 lb/in³
8.6 g/cm³0.31 lb/in³

Melting Point (Solidus)

1,186°C2,167 °F
1,250°C2,282 °F

Liquidus Temperature

1,383°C2,521 °F
1,320°C2,408 °F

Thermal

How each material carries heat and how hot it can run.

Thermal Conductivity

14.8 W/m·K8.6 BTU/hr·ft·°F
12 W/m·K6.9 BTU/hr·ft·°F

Specific Heat Capacity

423 J/kg·K0.1 BTU/lb·°F
420 J/kg·K0.1 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

14.2 µm/m·K7.9 µin/in·°F
12 µm/m·K6.7 µin/in·°F

Latent Heat of Fusion

270 J/g116 BTU/lb
—

Max Service Temperature (continuous)

760°C1,400 °F
800°C1,472 °F

Same in both: Min Service Temperature -196°C-321 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

2 % IACS
1.7 % IACS

Electrical Resistivity

8.6×10⁻⁷ Ω·m33.9 µΩ·in
1×10⁻⁶ Ω·m39.4 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Galvanic Potential (seawater, vs SCE)

-0.3 V
-0.25 V

Corrosion Resistance

80 / 100
78 / 100

Manufacturability

FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.

Machinability

15 / 100
4 / 100

Machinability Rating (AISI 1212 = 100 %)

10%
3%

Weldability

55 / 100
20 / 100

Formability (cold)

20 / 100
2 / 100

Castability

78 / 100
60 / 100

Brazeability / Solderability

55 / 100
45 / 100

Polishability

85 / 100
80 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

145 MJ/kg62,339 BTU/lb
170 MJ/kg73,087 BTU/lb

Embodied Carbon (primary production)

10 kg CO₂/kg
16 kg CO₂/kg

Embodied Water

420 L/kg50.3 gal/lb
400 L/kg47.9 gal/lb

Same in both: Typical Recycled Content 25%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

85 kN·m/kg
58 kN·m/kg

Specific Stiffness (E / density)

29.8 MN·m/kg
26.2 MN·m/kg

Modulus of Resilience

494 kJ/m³
512 kJ/m³

Thermal Diffusivity

4.2 mm²/s
3.3 mm²/s

Thermal Shock Resistance Index

3
2

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.

5007001,0001,5002,0008.28.48.68.89Density (g/cm³)Yield strength (MPa) — log scaleStellite 21Tribaloy T-800

Manufacturing and finishing

CapabilityStellite 21Tribaloy T-800
Default conditionAs Cast—
Relative cost$$$$$ Specialty$$$$ High
Min. machined wall——
Best machined surface——

Stellite 21 vs Tribaloy T-800 — frequently asked

Is Stellite 21 stronger than Tribaloy T-800?

Yes. Stellite 21 has a typical tensile strength of 710 MPa (103 ksi) against 500 MPa (72.5 ksi) for Tribaloy T-800 — about 42% more.

Which is cheaper, Stellite 21 or Tribaloy T-800?

Tribaloy T-800 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 Tribaloy T-800?

Stellite 21. Its machinability rates poor (15/100) against not recommended (4/100) for Tribaloy T-800; for welding the order is Stellite 21 first (good, 55/100) then Tribaloy T-800 (poor, 20/100).

Ready to make it?

Upload a CAD file and FabDigit prices the part in Stellite 21 and Tribaloy T-800 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.