SAE-AISI 8740 Steel vs. R30008 Cobalt
SAE-AISI 8740 steel belongs to the iron alloys classification, while R30008 cobalt belongs to the cobalt alloys. There are 23 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 SAE-AISI 8740 steel and the bottom bar is R30008 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 210 |
| Elongation at Break, % | 11 to 23 | |
| 1.1 to 73 |
| Fatigue Strength, MPa | 270 to 350 | |
| 320 to 530 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 73 | |
| 83 |
| Tensile Strength: Ultimate (UTS), MPa | 580 to 670 | |
| 950 to 1700 |
| Tensile Strength: Yield (Proof), MPa | 380 to 570 | |
| 500 to 1080 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 320 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1400 |
| Melting Onset (Solidus), °C | 1420 | |
| 1330 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 450 |
| Thermal Expansion, µm/m-K | 13 | |
| 13 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 2.6 | |
| 95 |
| Density, g/cm3 | 7.8 | |
| 8.4 |
| Embodied Carbon, kg CO2/kg material | 1.5 | |
| 8.1 |
| Embodied Energy, MJ/kg | 20 | |
| 110 |
| Embodied Water, L/kg | 50 | |
| 400 |
Common Calculations
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 390 to 850 | |
| 590 to 2720 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 20 to 24 | |
| 31 to 56 |
| Strength to Weight: Bending, points | 20 to 22 | |
| 25 to 37 |
| Thermal Shock Resistance, points | 17 to 20 | |
| 25 to 44 |
Alloy Composition
| Boron (B), % | 0 | |
| 0 to 0.0010 |
| Carbon (C), % | 0.38 to 0.43 | |
| 0 to 0.15 |
| Chromium (Cr), % | 0.4 to 0.6 | |
| 18.5 to 21.5 |
| Cobalt (Co), % | 0 | |
| 39 to 42 |
| Iron (Fe), % | 96.5 to 97.7 | |
| 7.6 to 20 |
| Manganese (Mn), % | 0.75 to 1.0 | |
| 1.0 to 2.0 |
| Molybdenum (Mo), % | 0.2 to 0.3 | |
| 6.5 to 7.5 |
| Nickel (Ni), % | 0.4 to 0.7 | |
| 15 to 18 |
| Phosphorus (P), % | 0 to 0.035 | |
| 0 to 0.015 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 0 to 1.2 |
| Sulfur (S), % | 0 to 0.040 | |
| 0 to 0.015 |