R30021 Cobalt vs. ASTM A231 Spring Steel
R30021 cobalt belongs to the cobalt alloys classification, while ASTM A231 spring steel belongs to the iron alloys. 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 R30021 cobalt and the bottom bar is ASTM A231 spring steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 220 | |
| 190 |
| Elongation at Break, % | 9.0 | |
| 14 |
| Fatigue Strength, MPa | 250 | |
| 1000 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 86 | |
| 73 |
| Tensile Strength: Ultimate (UTS), MPa | 700 | |
| 1790 |
| Tensile Strength: Yield (Proof), MPa | 500 | |
| 1570 |
Thermal Properties
| Latent Heat of Fusion, J/g | 330 | |
| 250 |
| Melting Completion (Liquidus), °C | 1350 | |
| 1460 |
| Melting Onset (Solidus), °C | 1190 | |
| 1410 |
| Specific Heat Capacity, J/kg-K | 450 | |
| 470 |
| Thermal Conductivity, W/m-K | 15 | |
| 52 |
| Thermal Expansion, µm/m-K | 11 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 1.9 | |
| 7.3 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 2.1 | |
| 8.4 |
Otherwise Unclassified Properties
| Density, g/cm3 | 8.4 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 8.0 | |
| 2.0 |
| Embodied Energy, MJ/kg | 110 | |
| 28 |
| Embodied Water, L/kg | 520 | |
| 51 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 57 | |
| 230 |
| Stiffness to Weight: Axial, points | 15 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 23 | |
| 64 |
| Strength to Weight: Bending, points | 21 | |
| 42 |
| Thermal Diffusivity, mm2/s | 3.8 | |
| 14 |
| Thermal Shock Resistance, points | 21 | |
| 53 |
Alloy Composition
| Carbon (C), % | 0.2 to 0.35 | |
| 0.48 to 0.53 |
| Chromium (Cr), % | 26 to 29 | |
| 0.8 to 1.1 |
| Cobalt (Co), % | 61.7 to 67.3 | |
| 0 |
| Iron (Fe), % | 0 to 3.0 | |
| 96.7 to 97.7 |
| Manganese (Mn), % | 0 | |
| 0.7 to 0.9 |
| Molybdenum (Mo), % | 4.5 to 6.0 | |
| 0 |
| Nickel (Ni), % | 2.0 to 3.0 | |
| 0 |
| Phosphorus (P), % | 0 | |
| 0 to 0.040 |
| Silicon (Si), % | 0 to 1.5 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 | |
| 0 to 0.040 |
| Vanadium (V), % | 0 | |
| 0.15 to 0.3 |