SAE-AISI 8740 Steel vs. R30605 Cobalt
SAE-AISI 8740 steel belongs to the iron alloys classification, while R30605 cobalt belongs to the cobalt alloys. There are 25 material properties with values for both materials. Properties with values for just one material (6, in this case) are not shown.
For each property being compared, the top bar is SAE-AISI 8740 steel and the bottom bar is R30605 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 210 |
| Elongation at Break, % | 11 to 23 | |
| 34 |
| Fatigue Strength, MPa | 270 to 350 | |
| 260 to 590 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 73 | |
| 81 |
| Tensile Strength: Ultimate (UTS), MPa | 580 to 670 | |
| 1130 to 1900 |
| Tensile Strength: Yield (Proof), MPa | 380 to 570 | |
| 470 to 1600 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 290 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1410 |
| Melting Onset (Solidus), °C | 1420 | |
| 1330 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 410 |
| Thermal Conductivity, W/m-K | 39 | |
| 9.6 |
| Thermal Expansion, µm/m-K | 13 | |
| 12 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.3 | |
| 2.0 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.4 | |
| 1.8 |
Otherwise Unclassified Properties
| Density, g/cm3 | 7.8 | |
| 9.6 |
| Embodied Carbon, kg CO2/kg material | 1.5 | |
| 9.8 |
| Embodied Energy, MJ/kg | 20 | |
| 140 |
| Embodied Water, L/kg | 50 | |
| 450 |
Common Calculations
| Stiffness to Weight: Axial, points | 13 | |
| 12 |
| Stiffness to Weight: Bending, points | 24 | |
| 21 |
| Strength to Weight: Axial, points | 20 to 24 | |
| 33 to 55 |
| Strength to Weight: Bending, points | 20 to 22 | |
| 25 to 36 |
| Thermal Diffusivity, mm2/s | 10 | |
| 2.5 |
| Thermal Shock Resistance, points | 17 to 20 | |
| 31 to 52 |
Alloy Composition
| Carbon (C), % | 0.38 to 0.43 | |
| 0.050 to 0.15 |
| Chromium (Cr), % | 0.4 to 0.6 | |
| 19 to 21 |
| Cobalt (Co), % | 0 | |
| 46.4 to 57 |
| Iron (Fe), % | 96.5 to 97.7 | |
| 0 to 3.0 |
| Manganese (Mn), % | 0.75 to 1.0 | |
| 1.0 to 2.0 |
| Molybdenum (Mo), % | 0.2 to 0.3 | |
| 0 |
| Nickel (Ni), % | 0.4 to 0.7 | |
| 9.0 to 11 |
| Phosphorus (P), % | 0 to 0.035 | |
| 0 to 0.040 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 0 to 0.4 |
| Sulfur (S), % | 0 to 0.040 | |
| 0 to 0.030 |
| Tungsten (W), % | 0 | |
| 14 to 16 |