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 mm2/s
Thermal Shock Resistance
14 points
Alloy Composition
| Co | 48 to 52 | |
| Cr | 27 to 30 | |
| Fe | 9.7 to 24.5 | |
| Ni | 0 to 4.0 | |
| Si | 0.5 to 1.5 | |
| Mn | 0 to 1.5 | |
| Mo | 0 to 0.5 | |
| Nb | 0 to 0.5 | |
| C | 0.050 to 0.25 | |
| P | 0 to 0.040 | |
| 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