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G-CoCr28 (2.4778) Cobalt-Chromium Alloy

G-CoCr28 cobalt is a cobalt alloy. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. 2.4778 is the EN numeric designation for this material. G-CoCr28 is the EN chemical designation.

It has the lowest tensile strength among cobalt alloys. In addition, it has the lowest thermal conductivity and the lowest embodied energy.

The graph bars on the material properties cards below compare G-CoCr28 cobalt to other cobalt alloys (top) and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Elastic (Young's, Tensile) Modulus

210 GPa 31 x 106 psi

Elongation at Break

6.7 %

Fatigue Strength

130 MPa 19 x 103 psi

Poisson's Ratio

0.28

Shear Modulus

83 GPa 12 x 106 psi

Tensile Strength: Ultimate (UTS)

560 MPa 81 x 103 psi

Tensile Strength: Yield (Proof)

260 MPa 38 x 103 psi

Thermal Properties

Latent Heat of Fusion

320 J/g

Maximum Temperature: Mechanical

1200 °C 2190 °F

Melting Completion (Liquidus)

1330 °C 2430 °F

Melting Onset (Solidus)

1270 °C 2310 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

8.5 W/m-K 4.9 BTU/h-ft-°F

Thermal Expansion

14 µm/m-K

Otherwise Unclassified Properties

Base Metal Price

100 % relative

Density

8.1 g/cm3 510 lb/ft3

Embodied Carbon

6.2 kg CO2/kg material

Embodied Energy

84 MJ/kg 36 x 103 BTU/lb

Embodied Water

440 L/kg 53 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

31 MJ/m3

Resilience: Unit (Modulus of Resilience)

160 kJ/m3

Stiffness to Weight: Axial

15 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

19 points

Strength to Weight: Bending

19 points

Thermal Diffusivity

2.2 m2/s

Thermal Shock Resistance

14 points

Alloy Composition

Cobalt (Co) 48 to 52
Chromium (Cr) 27 to 30
Iron (Fe) 9.7 to 24.5
Nickel (Ni) 0 to 4.0
Silicon (Si) 0.5 to 1.5
Manganese (Mn) 0 to 1.5
Molybdenum (Mo) 0 to 0.5
Niobium (Nb) 0 to 0.5
Carbon (C) 0.050 to 0.25
Phosphorus (P) 0 to 0.040
Sulfur (S) 0 to 0.030

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

EN 10295: Heat Resistant Steel Castings

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015