R30003 Cobalt vs. ASTM A387 Grade 21 Steel
R30003 cobalt belongs to the cobalt alloys classification, while ASTM A387 grade 21 steel belongs to the iron alloys. They have a modest 20% of their average alloy composition in common, which, by itself, doesn't mean much. There are 27 material properties with values for both materials. Properties with values for just one material (5, in this case) are not shown.
For each property being compared, the top bar is R30003 cobalt and the bottom bar is ASTM A387 grade 21 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 210 | |
| 190 |
| Elongation at Break, % | 10 to 73 | |
| 21 |
| Fatigue Strength, MPa | 320 to 560 | |
| 160 to 250 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 83 | |
| 74 |
| Tensile Strength: Ultimate (UTS), MPa | 970 to 1720 | |
| 500 to 590 |
| Tensile Strength: Yield (Proof), MPa | 510 to 1090 | |
| 230 to 350 |
Thermal Properties
| Latent Heat of Fusion, J/g | 310 | |
| 260 |
| Melting Completion (Liquidus), °C | 1400 | |
| 1470 |
| Melting Onset (Solidus), °C | 1440 | |
| 1430 |
| Specific Heat Capacity, J/kg-K | 450 | |
| 470 |
| Thermal Conductivity, W/m-K | 13 | |
| 41 |
| Thermal Expansion, µm/m-K | 13 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 2.0 | |
| 7.6 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 2.1 | |
| 8.8 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 95 | |
| 4.1 |
| Density, g/cm3 | 8.4 | |
| 7.9 |
| Embodied Carbon, kg CO2/kg material | 8.0 | |
| 1.8 |
| Embodied Energy, MJ/kg | 110 | |
| 23 |
| Embodied Water, L/kg | 400 | |
| 62 |
Common Calculations
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 600 to 2790 | |
| 140 to 320 |
| Stiffness to Weight: Axial, points | 14 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 32 to 57 | |
| 18 to 21 |
| Strength to Weight: Bending, points | 26 to 38 | |
| 18 to 20 |
| Thermal Diffusivity, mm2/s | 3.3 | |
| 11 |
| Thermal Shock Resistance, points | 26 to 45 | |
| 14 to 17 |
Alloy Composition
| Boron (B), % | 0 to 0.1 | |
| 0 |
| Carbon (C), % | 0 to 0.15 | |
| 0.050 to 0.15 |
| Chromium (Cr), % | 19 to 21 | |
| 2.8 to 3.3 |
| Cobalt (Co), % | 39 to 41 | |
| 0 |
| Iron (Fe), % | 10 to 20.5 | |
| 94.4 to 96 |
| Manganese (Mn), % | 1.5 to 2.5 | |
| 0.3 to 0.6 |
| Molybdenum (Mo), % | 6.0 to 8.0 | |
| 0.9 to 1.1 |
| Nickel (Ni), % | 14 to 16 | |
| 0 |
| Phosphorus (P), % | 0 to 0.015 | |
| 0 to 0.025 |
| Silicon (Si), % | 0 to 1.2 | |
| 0 to 0.5 |
| Sulfur (S), % | 0 to 0.015 | |
| 0 to 0.025 |