SAE-AISI 8645 Steel vs. R30816 Cobalt
SAE-AISI 8645 steel belongs to the iron alloys classification, while R30816 cobalt belongs to the cobalt alloys. There are 26 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 8645 steel and the bottom bar is R30816 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 180 to 200 | |
| 280 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 210 |
| Elongation at Break, % | 12 to 23 | |
| 23 |
| Fatigue Strength, MPa | 280 to 350 | |
| 250 |
| Poisson's Ratio | 0.29 | |
| 0.3 |
| Shear Modulus, GPa | 73 | |
| 81 |
| Tensile Strength: Ultimate (UTS), MPa | 600 to 670 | |
| 1020 |
| Tensile Strength: Yield (Proof), MPa | 390 to 560 | |
| 460 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 300 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1540 |
| Melting Onset (Solidus), °C | 1420 | |
| 1460 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 420 |
| Thermal Conductivity, W/m-K | 39 | |
| 13 |
| Thermal Expansion, µm/m-K | 13 | |
| 12 |
Otherwise Unclassified Properties
| Density, g/cm3 | 7.8 | |
| 9.1 |
| Embodied Carbon, kg CO2/kg material | 1.5 | |
| 20 |
| Embodied Energy, MJ/kg | 20 | |
| 320 |
| Embodied Water, L/kg | 50 | |
| 440 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 77 to 120 | |
| 190 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 420 to 840 | |
| 510 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 22 |
| Strength to Weight: Axial, points | 21 to 24 | |
| 31 |
| Strength to Weight: Bending, points | 20 to 22 | |
| 25 |
| Thermal Diffusivity, mm2/s | 10 | |
| 3.3 |
| Thermal Shock Resistance, points | 18 to 20 | |
| 28 |
Alloy Composition
| Carbon (C), % | 0.43 to 0.48 | |
| 0.32 to 0.42 |
| Chromium (Cr), % | 0.4 to 0.6 | |
| 19 to 21 |
| Cobalt (Co), % | 0 | |
| 40 to 49.8 |
| Iron (Fe), % | 96.5 to 97.7 | |
| 0 to 5.0 |
| Manganese (Mn), % | 0.75 to 1.0 | |
| 1.0 to 2.0 |
| Molybdenum (Mo), % | 0.15 to 0.25 | |
| 3.5 to 4.5 |
| Nickel (Ni), % | 0.4 to 0.7 | |
| 19 to 21 |
| Niobium (Nb), % | 0 | |
| 3.5 to 4.5 |
| Phosphorus (P), % | 0 to 0.035 | |
| 0 to 0.040 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 0 to 1.0 |
| Sulfur (S), % | 0 to 0.040 | |
| 0 to 0.030 |
| Tantalum (Ta), % | 0 | |
| 3.5 to 4.5 |
| Tungsten (W), % | 0 | |
| 3.5 to 4.5 |