Nickel 718 vs. R31538 Cobalt
Nickel 718 belongs to the nickel alloys classification, while R31538 cobalt belongs to the cobalt alloys. They have a modest 24% of their average alloy composition in common, which, by itself, doesn't mean much. There are 29 material properties with values for both materials. Properties with values for just one material (5, in this case) are not shown.
For each property being compared, the top bar is nickel 718 and the bottom bar is R31538 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 220 |
| Elongation at Break, % | 12 to 50 | |
| 13 to 23 |
| Fatigue Strength, MPa | 460 to 760 | |
| 310 to 480 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Reduction in Area, % | 34 to 64 | |
| 13 to 22 |
| Rockwell C Hardness | 40 | |
| 25 to 35 |
| Shear Modulus, GPa | 75 | |
| 86 |
| Tensile Strength: Ultimate (UTS), MPa | 930 to 1530 | |
| 1020 to 1360 |
| Tensile Strength: Yield (Proof), MPa | 510 to 1330 | |
| 580 to 930 |
Thermal Properties
| Latent Heat of Fusion, J/g | 310 | |
| 320 |
| Melting Completion (Liquidus), °C | 1340 | |
| 1360 |
| Melting Onset (Solidus), °C | 1260 | |
| 1290 |
| Specific Heat Capacity, J/kg-K | 450 | |
| 450 |
| Thermal Conductivity, W/m-K | 11 | |
| 13 |
| Thermal Expansion, µm/m-K | 13 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 1.4 | |
| 2.0 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 1.5 | |
| 2.1 |
Otherwise Unclassified Properties
| Density, g/cm3 | 8.3 | |
| 8.4 |
| Embodied Carbon, kg CO2/kg material | 13 | |
| 8.1 |
| Embodied Energy, MJ/kg | 190 | |
| 110 |
| Embodied Water, L/kg | 250 | |
| 530 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 140 to 390 | |
| 140 to 200 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 660 to 4560 | |
| 750 to 1920 |
| Stiffness to Weight: Axial, points | 13 | |
| 15 |
| Stiffness to Weight: Bending, points | 23 | |
| 24 |
| Strength to Weight: Axial, points | 31 to 51 | |
| 34 to 45 |
| Strength to Weight: Bending, points | 25 to 35 | |
| 27 to 32 |
| Thermal Diffusivity, mm2/s | 3.0 | |
| 3.5 |
| Thermal Shock Resistance, points | 27 to 44 | |
| 25 to 33 |
Alloy Composition
| Aluminum (Al), % | 0.2 to 0.8 | |
| 0 |
| Boron (B), % | 0 to 0.0060 | |
| 0 |
| Carbon (C), % | 0 to 0.080 | |
| 0.15 to 0.35 |
| Chromium (Cr), % | 17 to 21 | |
| 26 to 30 |
| Cobalt (Co), % | 0 to 1.0 | |
| 58.7 to 68.9 |
| Copper (Cu), % | 0 to 0.3 | |
| 0 |
| Iron (Fe), % | 11.1 to 24.6 | |
| 0 to 0.75 |
| Manganese (Mn), % | 0 to 0.35 | |
| 0 to 1.0 |
| Molybdenum (Mo), % | 2.8 to 3.3 | |
| 5.0 to 7.0 |
| Nickel (Ni), % | 50 to 55 | |
| 0 to 1.0 |
| Niobium (Nb), % | 4.8 to 5.5 | |
| 0 |
| Nitrogen (N), % | 0 | |
| 0 to 0.25 |
| Phosphorus (P), % | 0 to 0.015 | |
| 0 |
| Silicon (Si), % | 0 to 0.35 | |
| 0 to 1.0 |
| Sulfur (S), % | 0 to 0.015 | |
| 0 |
| Titanium (Ti), % | 0.65 to 1.2 | |
| 0 |