R30816 Cobalt vs. S21904 Stainless Steel
R30816 cobalt belongs to the cobalt alloys classification, while S21904 stainless steel belongs to the iron alloys. They have a modest 31% of their average alloy composition in common, which, by itself, doesn't mean much. There are 26 material properties with values for both materials. Properties with values for just one material (8, in this case) are not shown.
For each property being compared, the top bar is R30816 cobalt and the bottom bar is S21904 stainless steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 280 | |
| 210 to 300 |
| Elastic (Young's, Tensile) Modulus, GPa | 210 | |
| 200 |
| Elongation at Break, % | 23 | |
| 17 to 51 |
| Fatigue Strength, MPa | 250 | |
| 380 to 550 |
| Poisson's Ratio | 0.3 | |
| 0.28 |
| Shear Modulus, GPa | 81 | |
| 78 |
| Tensile Strength: Ultimate (UTS), MPa | 1020 | |
| 700 to 1000 |
| Tensile Strength: Yield (Proof), MPa | 460 | |
| 390 to 910 |
Thermal Properties
| Latent Heat of Fusion, J/g | 300 | |
| 290 |
| Melting Completion (Liquidus), °C | 1540 | |
| 1400 |
| Melting Onset (Solidus), °C | 1460 | |
| 1350 |
| Specific Heat Capacity, J/kg-K | 420 | |
| 480 |
| Thermal Conductivity, W/m-K | 13 | |
| 14 |
| Thermal Expansion, µm/m-K | 12 | |
| 17 |
Otherwise Unclassified Properties
| Density, g/cm3 | 9.1 | |
| 7.7 |
| Embodied Carbon, kg CO2/kg material | 20 | |
| 3.0 |
| Embodied Energy, MJ/kg | 320 | |
| 43 |
| Embodied Water, L/kg | 440 | |
| 160 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 190 | |
| 160 to 310 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 510 | |
| 380 to 2070 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 |
| Stiffness to Weight: Bending, points | 22 | |
| 25 |
| Strength to Weight: Axial, points | 31 | |
| 25 to 36 |
| Strength to Weight: Bending, points | 25 | |
| 23 to 29 |
| Thermal Diffusivity, mm2/s | 3.3 | |
| 3.8 |
| Thermal Shock Resistance, points | 28 | |
| 15 to 21 |
Alloy Composition
| Carbon (C), % | 0.32 to 0.42 | |
| 0 to 0.040 |
| Chromium (Cr), % | 19 to 21 | |
| 19 to 21.5 |
| Cobalt (Co), % | 40 to 49.8 | |
| 0 |
| Iron (Fe), % | 0 to 5.0 | |
| 59.5 to 67.4 |
| Manganese (Mn), % | 1.0 to 2.0 | |
| 8.0 to 10 |
| Molybdenum (Mo), % | 3.5 to 4.5 | |
| 0 |
| Nickel (Ni), % | 19 to 21 | |
| 5.5 to 7.5 |
| Niobium (Nb), % | 3.5 to 4.5 | |
| 0 |
| Nitrogen (N), % | 0 | |
| 0.15 to 0.4 |
| Phosphorus (P), % | 0 to 0.040 | |
| 0 to 0.045 |
| Silicon (Si), % | 0 to 1.0 | |
| 0 to 1.0 |
| Sulfur (S), % | 0 to 0.030 | |
| 0 to 0.030 |
| Tantalum (Ta), % | 3.5 to 4.5 | |
| 0 |
| Tungsten (W), % | 3.5 to 4.5 | |
| 0 |