SAE-AISI P21 Steel vs. R30021 Cobalt
SAE-AISI P21 steel belongs to the iron alloys classification, while R30021 cobalt belongs to the cobalt alloys. There are 23 material properties with values for both materials. Properties with values for just one material (7, in this case) are not shown.
For each property being compared, the top bar is SAE-AISI P21 steel and the bottom bar is R30021 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 220 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Rockwell C Hardness | 35 | |
| 32 |
| Shear Modulus, GPa | 73 | |
| 86 |
| Tensile Strength: Ultimate (UTS), MPa | 1130 | |
| 700 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 330 |
| Melting Completion (Liquidus), °C | 1450 | |
| 1350 |
| Melting Onset (Solidus), °C | 1410 | |
| 1190 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 450 |
| Thermal Conductivity, W/m-K | 41 | |
| 15 |
| Thermal Expansion, µm/m-K | 12 | |
| 11 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.9 | |
| 1.9 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 9.0 | |
| 2.1 |
Otherwise Unclassified Properties
| Density, g/cm3 | 7.9 | |
| 8.4 |
| Embodied Carbon, kg CO2/kg material | 2.3 | |
| 8.0 |
| Embodied Energy, MJ/kg | 32 | |
| 110 |
| Embodied Water, L/kg | 62 | |
| 520 |
Common Calculations
| Stiffness to Weight: Axial, points | 13 | |
| 15 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 40 | |
| 23 |
| Strength to Weight: Bending, points | 31 | |
| 21 |
| Thermal Diffusivity, mm2/s | 11 | |
| 3.8 |
| Thermal Shock Resistance, points | 37 | |
| 21 |
Alloy Composition
| Carbon (C), % | 0.18 to 0.22 | |
| 0.2 to 0.35 |
| Chromium (Cr), % | 0 to 0.5 | |
| 26 to 29 |
| Cobalt (Co), % | 1.1 to 1.3 | |
| 61.7 to 67.3 |
| Copper (Cu), % | 0 to 0.25 | |
| 0 |
| Iron (Fe), % | 92.1 to 94.2 | |
| 0 to 3.0 |
| Manganese (Mn), % | 0.35 to 0.72 | |
| 0 |
| Molybdenum (Mo), % | 0 | |
| 4.5 to 6.0 |
| Nickel (Ni), % | 3.9 to 4.3 | |
| 2.0 to 3.0 |
| Phosphorus (P), % | 0 to 0.030 | |
| 0 |
| Silicon (Si), % | 0.2 to 0.4 | |
| 0 to 1.5 |
| Sulfur (S), % | 0 to 0.030 | |
| 0 |
| Vanadium (V), % | 0.15 to 0.25 | |
| 0 |