AISI 440B Stainless Steel vs. R30008 Cobalt
AISI 440B stainless steel belongs to the iron alloys classification, while R30008 cobalt belongs to the cobalt alloys. They have a modest 32% of their average alloy composition in common, which, by itself, doesn't mean much. There are 22 material properties with values for both materials. Properties with values for just one material (10, in this case) are not shown.
For each property being compared, the top bar is AISI 440B stainless steel and the bottom bar is R30008 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 200 | |
| 210 |
| Elongation at Break, % | 3.0 to 18 | |
| 1.1 to 73 |
| Fatigue Strength, MPa | 260 to 850 | |
| 320 to 530 |
| Poisson's Ratio | 0.28 | |
| 0.29 |
| Shear Modulus, GPa | 77 | |
| 83 |
| Tensile Strength: Ultimate (UTS), MPa | 740 to 1930 | |
| 950 to 1700 |
| Tensile Strength: Yield (Proof), MPa | 430 to 1860 | |
| 500 to 1080 |
Thermal Properties
| Latent Heat of Fusion, J/g | 280 | |
| 320 |
| Melting Completion (Liquidus), °C | 1480 | |
| 1400 |
| Melting Onset (Solidus), °C | 1370 | |
| 1330 |
| Specific Heat Capacity, J/kg-K | 480 | |
| 450 |
| Thermal Expansion, µm/m-K | 10 | |
| 13 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 9.0 | |
| 95 |
| Density, g/cm3 | 7.7 | |
| 8.4 |
| Embodied Carbon, kg CO2/kg material | 2.2 | |
| 8.1 |
| Embodied Energy, MJ/kg | 31 | |
| 110 |
| Embodied Water, L/kg | 120 | |
| 400 |
Common Calculations
| Stiffness to Weight: Axial, points | 14 | |
| 14 |
| Stiffness to Weight: Bending, points | 25 | |
| 24 |
| Strength to Weight: Axial, points | 27 to 70 | |
| 31 to 56 |
| Strength to Weight: Bending, points | 24 to 45 | |
| 25 to 37 |
| Thermal Shock Resistance, points | 27 to 70 | |
| 25 to 44 |
Alloy Composition
| Boron (B), % | 0 | |
| 0 to 0.0010 |
| Carbon (C), % | 0.75 to 1.0 | |
| 0 to 0.15 |
| Chromium (Cr), % | 16 to 18 | |
| 18.5 to 21.5 |
| Cobalt (Co), % | 0 | |
| 39 to 42 |
| Iron (Fe), % | 78.2 to 83.3 | |
| 7.6 to 20 |
| Manganese (Mn), % | 0 to 1.0 | |
| 1.0 to 2.0 |
| Molybdenum (Mo), % | 0 to 0.75 | |
| 6.5 to 7.5 |
| Nickel (Ni), % | 0 | |
| 15 to 18 |
| Phosphorus (P), % | 0 to 0.040 | |
| 0 to 0.015 |
| Silicon (Si), % | 0 to 1.0 | |
| 0 to 1.2 |
| Sulfur (S), % | 0 to 0.015 | |
| 0 to 0.015 |