Annealed R31538 Cobalt vs. Annealed S21904 Stainless Steel
Annealed R31538 cobalt belongs to the cobalt alloys classification, while annealed S21904 stainless steel belongs to the iron alloys. They have a modest 22% of their average alloy composition in common, which, by itself, doesn't mean much. There are 28 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 annealed R31538 cobalt and the bottom bar is annealed S21904 stainless steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 220 | |
| 200 |
| Elongation at Break, % | 23 | |
| 51 |
| Fatigue Strength, MPa | 310 | |
| 380 |
| Poisson's Ratio | 0.29 | |
| 0.28 |
| Reduction in Area, % | 22 | |
| 64 |
| Shear Modulus, GPa | 86 | |
| 78 |
| Tensile Strength: Ultimate (UTS), MPa | 1020 | |
| 700 |
| Tensile Strength: Yield (Proof), MPa | 580 | |
| 390 |
Thermal Properties
| Latent Heat of Fusion, J/g | 320 | |
| 290 |
| Melting Completion (Liquidus), °C | 1360 | |
| 1400 |
| Melting Onset (Solidus), °C | 1290 | |
| 1350 |
| Specific Heat Capacity, J/kg-K | 450 | |
| 480 |
| Thermal Conductivity, W/m-K | 13 | |
| 14 |
| Thermal Expansion, µm/m-K | 13 | |
| 17 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 2.0 | |
| 2.5 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 2.1 | |
| 2.9 |
Otherwise Unclassified Properties
| Density, g/cm3 | 8.4 | |
| 7.7 |
| Embodied Carbon, kg CO2/kg material | 8.1 | |
| 3.0 |
| Embodied Energy, MJ/kg | 110 | |
| 43 |
| Embodied Water, L/kg | 530 | |
| 160 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 200 | |
| 310 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 750 | |
| 380 |
| Stiffness to Weight: Axial, points | 15 | |
| 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 25 |
| Strength to Weight: Axial, points | 34 | |
| 25 |
| Strength to Weight: Bending, points | 27 | |
| 23 |
| Thermal Diffusivity, mm2/s | 3.5 | |
| 3.8 |
| Thermal Shock Resistance, points | 25 | |
| 15 |
Alloy Composition
| Carbon (C), % | 0.15 to 0.35 | |
| 0 to 0.040 |
| Chromium (Cr), % | 26 to 30 | |
| 19 to 21.5 |
| Cobalt (Co), % | 58.7 to 68.9 | |
| 0 |
| Iron (Fe), % | 0 to 0.75 | |
| 59.5 to 67.4 |
| Manganese (Mn), % | 0 to 1.0 | |
| 8.0 to 10 |
| Molybdenum (Mo), % | 5.0 to 7.0 | |
| 0 |
| Nickel (Ni), % | 0 to 1.0 | |
| 5.5 to 7.5 |
| Nitrogen (N), % | 0 to 0.25 | |
| 0.15 to 0.4 |
| Phosphorus (P), % | 0 | |
| 0 to 0.045 |
| Silicon (Si), % | 0 to 1.0 | |
| 0 to 1.0 |
| Sulfur (S), % | 0 | |
| 0 to 0.030 |