R31539 Cobalt vs. SAE-AISI 8645 Steel
R31539 cobalt belongs to the cobalt alloys classification, while SAE-AISI 8645 steel belongs to the iron alloys. There are 27 material properties with values for both materials. Properties with values for just one material (6, in this case) are not shown.
For each property being compared, the top bar is R31539 cobalt and the bottom bar is SAE-AISI 8645 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 220 | |
| 190 |
| Elongation at Break, % | 13 to 22 | |
| 12 to 23 |
| Fatigue Strength, MPa | 310 to 480 | |
| 280 to 350 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 86 | |
| 73 |
| Tensile Strength: Ultimate (UTS), MPa | 1000 to 1340 | |
| 600 to 670 |
| Tensile Strength: Yield (Proof), MPa | 590 to 940 | |
| 390 to 560 |
Thermal Properties
| Latent Heat of Fusion, J/g | 320 | |
| 250 |
| Melting Completion (Liquidus), °C | 1360 | |
| 1460 |
| Melting Onset (Solidus), °C | 1290 | |
| 1420 |
| Specific Heat Capacity, J/kg-K | 450 | |
| 470 |
| Thermal Conductivity, W/m-K | 13 | |
| 39 |
| Thermal Expansion, µm/m-K | 13 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 2.0 | |
| 7.3 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 2.1 | |
| 8.4 |
Otherwise Unclassified Properties
| Density, g/cm3 | 8.4 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 8.2 | |
| 1.5 |
| Embodied Energy, MJ/kg | 110 | |
| 20 |
| Embodied Water, L/kg | 530 | |
| 50 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 140 to 190 | |
| 77 to 120 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 780 to 2000 | |
| 420 to 840 |
| Stiffness to Weight: Axial, points | 15 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 33 to 44 | |
| 21 to 24 |
| Strength to Weight: Bending, points | 27 to 32 | |
| 20 to 22 |
| Thermal Diffusivity, mm2/s | 3.5 | |
| 10 |
| Thermal Shock Resistance, points | 24 to 32 | |
| 18 to 20 |
Alloy Composition
| Aluminum (Al), % | 0.3 to 1.0 | |
| 0 |
| Carbon (C), % | 0 to 0.14 | |
| 0.43 to 0.48 |
| Chromium (Cr), % | 26 to 30 | |
| 0.4 to 0.6 |
| Cobalt (Co), % | 57.7 to 68.7 | |
| 0 |
| Iron (Fe), % | 0 to 0.75 | |
| 96.5 to 97.7 |
| Lanthanum (La), % | 0.030 to 0.2 | |
| 0 |
| Manganese (Mn), % | 0 to 1.0 | |
| 0.75 to 1.0 |
| Molybdenum (Mo), % | 5.0 to 7.0 | |
| 0.15 to 0.25 |
| Nickel (Ni), % | 0 to 1.0 | |
| 0.4 to 0.7 |
| Nitrogen (N), % | 0 to 0.25 | |
| 0 |
| Phosphorus (P), % | 0 | |
| 0 to 0.035 |
| Silicon (Si), % | 0 to 1.0 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 | |
| 0 to 0.040 |