S31730 Stainless Steel vs. R30021 Cobalt
S31730 stainless steel belongs to the iron alloys classification, while R30021 cobalt belongs to the cobalt alloys. They have a modest 26% of their average alloy composition in common, which, by itself, doesn't mean much. There are 23 material properties with values for both materials. Properties with values for just one material (13, in this case) are not shown.
For each property being compared, the top bar is S31730 stainless steel and the bottom bar is R30021 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 200 | |
| 220 |
| Elongation at Break, % | 40 | |
| 9.0 |
| Fatigue Strength, MPa | 170 | |
| 250 |
| Poisson's Ratio | 0.28 | |
| 0.29 |
| Shear Modulus, GPa | 77 | |
| 86 |
| Tensile Strength: Ultimate (UTS), MPa | 540 | |
| 700 |
| Tensile Strength: Yield (Proof), MPa | 200 | |
| 500 |
Thermal Properties
| Latent Heat of Fusion, J/g | 290 | |
| 330 |
| Melting Completion (Liquidus), °C | 1430 | |
| 1350 |
| Melting Onset (Solidus), °C | 1390 | |
| 1190 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 450 |
| Thermal Expansion, µm/m-K | 16 | |
| 11 |
Otherwise Unclassified Properties
| Density, g/cm3 | 8.0 | |
| 8.4 |
| Embodied Carbon, kg CO2/kg material | 4.6 | |
| 8.0 |
| Embodied Energy, MJ/kg | 63 | |
| 110 |
| Embodied Water, L/kg | 180 | |
| 520 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 170 | |
| 57 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 99 | |
| 570 |
| Stiffness to Weight: Axial, points | 14 | |
| 15 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 19 | |
| 23 |
| Strength to Weight: Bending, points | 18 | |
| 21 |
| Thermal Shock Resistance, points | 12 | |
| 21 |
Alloy Composition
| Carbon (C), % | 0 to 0.030 | |
| 0.2 to 0.35 |
| Chromium (Cr), % | 17 to 19 | |
| 26 to 29 |
| Cobalt (Co), % | 0 | |
| 61.7 to 67.3 |
| Copper (Cu), % | 4.0 to 5.0 | |
| 0 |
| Iron (Fe), % | 52.4 to 61 | |
| 0 to 3.0 |
| Manganese (Mn), % | 0 to 2.0 | |
| 0 |
| Molybdenum (Mo), % | 3.0 to 4.0 | |
| 4.5 to 6.0 |
| Nickel (Ni), % | 15 to 16.5 | |
| 2.0 to 3.0 |
| Nitrogen (N), % | 0 to 0.045 | |
| 0 |
| Phosphorus (P), % | 0 to 0.040 | |
| 0 |
| Silicon (Si), % | 0 to 1.0 | |
| 0 to 1.5 |
| Sulfur (S), % | 0 to 0.010 | |
| 0 |