S81921 Stainless Steel vs. R30001 Cobalt
S81921 stainless steel belongs to the iron alloys classification, while R30001 cobalt belongs to the cobalt alloys. They have a modest 25% of their average alloy composition in common, which, by itself, doesn't mean much. There are 24 material properties with values for both materials. Properties with values for just one material (11, in this case) are not shown.
For each property being compared, the top bar is S81921 stainless steel and the bottom bar is R30001 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 200 | |
| 220 |
| Elongation at Break, % | 29 | |
| 1.0 |
| Poisson's Ratio | 0.28 | |
| 0.28 |
| Rockwell C Hardness | 27 | |
| 55 |
| Shear Modulus, GPa | 79 | |
| 86 |
| Tensile Strength: Ultimate (UTS), MPa | 710 | |
| 620 |
Thermal Properties
| Latent Heat of Fusion, J/g | 290 | |
| 310 |
| Melting Completion (Liquidus), °C | 1430 | |
| 1530 |
| Melting Onset (Solidus), °C | 1390 | |
| 1260 |
| Specific Heat Capacity, J/kg-K | 480 | |
| 430 |
| Thermal Conductivity, W/m-K | 15 | |
| 15 |
| Thermal Expansion, µm/m-K | 13 | |
| 11 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 2.2 | |
| 1.8 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 2.5 | |
| 1.8 |
Otherwise Unclassified Properties
| Density, g/cm3 | 7.7 | |
| 9.0 |
| Embodied Carbon, kg CO2/kg material | 2.9 | |
| 8.9 |
| Embodied Energy, MJ/kg | 41 | |
| 130 |
| Embodied Water, L/kg | 150 | |
| 460 |
Common Calculations
| Stiffness to Weight: Axial, points | 14 | |
| 14 |
| Stiffness to Weight: Bending, points | 25 | |
| 22 |
| Strength to Weight: Axial, points | 25 | |
| 19 |
| Strength to Weight: Bending, points | 23 | |
| 18 |
| Thermal Diffusivity, mm2/s | 4.0 | |
| 3.7 |
| Thermal Shock Resistance, points | 20 | |
| 19 |
Alloy Composition
| Carbon (C), % | 0 to 0.030 | |
| 2.0 to 3.0 |
| Chromium (Cr), % | 19 to 22 | |
| 28 to 32 |
| Cobalt (Co), % | 0 | |
| 43 to 59 |
| Iron (Fe), % | 66.7 to 75.9 | |
| 0 to 3.0 |
| Manganese (Mn), % | 2.0 to 4.0 | |
| 0 |
| Molybdenum (Mo), % | 1.0 to 2.0 | |
| 0 to 1.0 |
| Nickel (Ni), % | 2.0 to 4.0 | |
| 0 to 3.0 |
| Nitrogen (N), % | 0.14 to 0.2 | |
| 0 |
| Phosphorus (P), % | 0 to 0.040 | |
| 0 |
| Silicon (Si), % | 0 to 1.0 | |
| 0 to 2.0 |
| Sulfur (S), % | 0 to 0.030 | |
| 0 |
| Tungsten (W), % | 0 | |
| 11 to 13 |