UNS R30816 (formerly Grade 671) Cobalt
R30816 cobalt is a cobalt alloy. Cited properties are appropriate for the annealed and aged condition. R30816 is the UNS number for this material. Older literature may refer to this material as ASTM Grade 671, but this is now discouraged.
It has the highest embodied energy among cobalt alloys. In addition, it has a very high melting temperature and a fairly low heat capacity.
The graph bars on the material properties cards below compare R30816 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
Brinell Hardness
280
Elastic (Young's, Tensile) Modulus
210 GPa 31 x 106 psi
Elongation at Break
23 %
Fatigue Strength
250 MPa 36 x 103 psi
Poisson's Ratio
0.3
Reduction in Area
22 %
Shear Modulus
81 GPa 12 x 106 psi
Tensile Strength: Ultimate (UTS)
1020 MPa 150 x 103 psi
Tensile Strength: Yield (Proof)
460 MPa 67 x 103 psi
Thermal Properties
Latent Heat of Fusion
300 J/g
Melting Completion (Liquidus)
1540 °C 2800 °F
Melting Onset (Solidus)
1460 °C 2660 °F
Specific Heat Capacity
420 J/kg-K 0.1 BTU/lb-°F
Thermal Conductivity
13 W/m-K 7.3 BTU/h-ft-°F
Thermal Expansion
12 µm/m-K
Otherwise Unclassified Properties
Density
9.1 g/cm3 570 lb/ft3
Embodied Carbon
20 kg CO2/kg material
Embodied Energy
320 MJ/kg 140 x 103 BTU/lb
Embodied Water
440 L/kg 52 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
190 MJ/m3
Resilience: Unit (Modulus of Resilience)
510 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
22 points
Strength to Weight: Axial
31 points
Strength to Weight: Bending
25 points
Thermal Diffusivity
3.3 mm2/s
Thermal Shock Resistance
28 points
Alloy Composition
| Co | 40 to 49.8 | |
| Ni | 19 to 21 | |
| Cr | 19 to 21 | |
| Mo | 3.5 to 4.5 | |
| W | 3.5 to 4.5 | |
| Nb | 3.5 to 4.5 | |
| Ta | 3.5 to 4.5 | |
| Fe | 0 to 5.0 | |
| Mn | 1.0 to 2.0 | |
| Si | 0 to 1.0 | |
| C | 0.32 to 0.42 | |
| 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
ASTM B639: Standard Specification for Precipitation Hardening Cobalt-Containing Alloys (UNS R30155 and UNS R30816) Rod, Bar, Forgings, and Forging Stock for High-Temperature Service
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015