ASTM A387 Grade 21 Steel vs. R30035 Cobalt
ASTM A387 grade 21 steel belongs to the iron alloys classification, while R30035 cobalt belongs to the cobalt alloys. There are 28 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 ASTM A387 grade 21 steel and the bottom bar is R30035 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 220 to 230 |
| Elongation at Break, % | 21 | |
| 9.0 to 46 |
| Fatigue Strength, MPa | 160 to 250 | |
| 170 to 740 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 74 | |
| 84 to 89 |
| Tensile Strength: Ultimate (UTS), MPa | 500 to 590 | |
| 900 to 1900 |
| Tensile Strength: Yield (Proof), MPa | 230 to 350 | |
| 300 to 1650 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 320 |
| Melting Completion (Liquidus), °C | 1470 | |
| 1440 |
| Melting Onset (Solidus), °C | 1430 | |
| 1320 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 440 |
| Thermal Conductivity, W/m-K | 41 | |
| 11 |
| Thermal Expansion, µm/m-K | 13 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.6 | |
| 1.7 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.8 | |
| 1.8 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 4.1 | |
| 100 |
| Density, g/cm3 | 7.9 | |
| 8.7 |
| Embodied Carbon, kg CO2/kg material | 1.8 | |
| 10 |
| Embodied Energy, MJ/kg | 23 | |
| 140 |
| Embodied Water, L/kg | 62 | |
| 410 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 84 to 110 | |
| 160 to 320 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 140 to 320 | |
| 210 to 5920 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 to 15 |
| Stiffness to Weight: Bending, points | 24 | |
| 23 to 24 |
| Strength to Weight: Axial, points | 18 to 21 | |
| 29 to 61 |
| Strength to Weight: Bending, points | 18 to 20 | |
| 24 to 39 |
| Thermal Diffusivity, mm2/s | 11 | |
| 3.0 |
| Thermal Shock Resistance, points | 14 to 17 | |
| 23 to 46 |
Alloy Composition
| Boron (B), % | 0 | |
| 0 to 0.015 |
| Carbon (C), % | 0.050 to 0.15 | |
| 0 to 0.025 |
| Chromium (Cr), % | 2.8 to 3.3 | |
| 19 to 21 |
| Cobalt (Co), % | 0 | |
| 29.1 to 39 |
| Iron (Fe), % | 94.4 to 96 | |
| 0 to 1.0 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0 to 0.15 |
| Molybdenum (Mo), % | 0.9 to 1.1 | |
| 9.0 to 10.5 |
| Nickel (Ni), % | 0 | |
| 33 to 37 |
| Phosphorus (P), % | 0 to 0.025 | |
| 0 to 0.015 |
| Silicon (Si), % | 0 to 0.5 | |
| 0 to 0.15 |
| Sulfur (S), % | 0 to 0.025 | |
| 0 to 0.010 |
| Titanium (Ti), % | 0 | |
| 0 to 1.0 |