UNS R31233 Cobalt
R31233 cobalt is a cobalt alloy. Cited properties are appropriate for the annealed condition. It has a moderately high melting temperature among cobalt alloys. In addition, it has a moderately low heat capacity and a moderately low thermal conductivity.
The graph bars on the material properties cards below compare R31233 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
220 GPa 32 x 106 psi
Elongation at Break
17 %
Fatigue Strength
220 MPa 32 x 103 psi
Poisson's Ratio
0.29
Shear Modulus
85 GPa 12 x 106 psi
Tensile Strength: Ultimate (UTS)
1020 MPa 150 x 103 psi
Tensile Strength: Yield (Proof)
420 MPa 62 x 103 psi
Thermal Properties
Latent Heat of Fusion
320 J/g
Melting Completion (Liquidus)
1350 °C 2470 °F
Melting Onset (Solidus)
1330 °C 2430 °F
Specific Heat Capacity
440 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
12 W/m-K 7.1 BTU/h-ft-°F
Thermal Expansion
13 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
2.0 % IACS
Electrical Conductivity: Equal Weight (Specific)
2.1 % IACS
Otherwise Unclassified Properties
Density
8.6 g/cm3 540 lb/ft3
Embodied Carbon
8.4 kg CO2/kg material
Embodied Energy
110 MJ/kg 49 x 103 BTU/lb
Embodied Water
480 L/kg 57 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
140 MJ/m3
Resilience: Unit (Modulus of Resilience)
410 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
23 points
Strength to Weight: Axial
33 points
Strength to Weight: Bending
26 points
Thermal Diffusivity
3.2 mm2/s
Thermal Shock Resistance
25 points
Alloy Composition
| Co | 44.7 to 63.3 | |
| Cr | 23.5 to 27.5 | |
| Ni | 7.0 to 11 | |
| Mo | 4.0 to 6.0 | |
| Fe | 1.0 to 5.0 | |
| W | 1.0 to 3.0 | |
| Mn | 0.1 to 1.5 | |
| Si | 0.050 to 1.0 | |
| N | 0.030 to 0.12 | |
| C | 0.020 to 0.1 | |
| P | 0 to 0.030 | |
| S | 0 to 0.020 | |
| B | 0 to 0.015 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B815: Standard Specification for Cobalt-Chromium-Nickel-Molybdenum-Tungsten Alloy (UNS R31233) Rod
ASTM B818: Standard Specification for Cobalt-Chromium-Nickel-Molybdenum-Tungsten Alloy (UNS R31233) Plate, Sheet and Strip
ASM Specialty Handbook: Nickel, Cobalt, and Their Alloys, Joseph R. Davis (editor), 2000
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015