ASTM A387 Grade 91 Class 2 vs. R30008 Cobalt
ASTM A387 grade 91 class 2 belongs to the iron alloys classification, while R30008 cobalt belongs to the cobalt alloys. They have a modest 25% of their average alloy composition in common, which, by itself, doesn't mean much. There are 23 material properties with values for both materials. Properties with values for just one material (9, in this case) are not shown.
For each property being compared, the top bar is ASTM A387 grade 91 class 2 and the bottom bar is R30008 cobalt.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 210 |
| Elongation at Break, % | 20 | |
| 1.1 to 73 |
| Fatigue Strength, MPa | 330 | |
| 320 to 530 |
| Poisson's Ratio | 0.28 | |
| 0.29 |
| Shear Modulus, GPa | 75 | |
| 83 |
| Tensile Strength: Ultimate (UTS), MPa | 670 | |
| 950 to 1700 |
| Tensile Strength: Yield (Proof), MPa | 470 | |
| 500 to 1080 |
Thermal Properties
| Latent Heat of Fusion, J/g | 270 | |
| 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 | 7.0 | |
| 95 |
| Density, g/cm3 | 7.8 | |
| 8.4 |
| Embodied Carbon, kg CO2/kg material | 2.6 | |
| 8.1 |
| Embodied Energy, MJ/kg | 37 | |
| 110 |
| Embodied Water, L/kg | 88 | |
| 400 |
Common Calculations
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 580 | |
| 590 to 2720 |
| Stiffness to Weight: Axial, points | 14 | |
| 14 |
| Stiffness to Weight: Bending, points | 25 | |
| 24 |
| Strength to Weight: Axial, points | 24 | |
| 31 to 56 |
| Strength to Weight: Bending, points | 22 | |
| 25 to 37 |
| Thermal Shock Resistance, points | 19 | |
| 25 to 44 |
Alloy Composition
| Aluminum (Al), % | 0 to 0.020 | |
| 0 |
| Boron (B), % | 0 | |
| 0 to 0.0010 |
| Carbon (C), % | 0.080 to 0.12 | |
| 0 to 0.15 |
| Chromium (Cr), % | 8.0 to 9.5 | |
| 18.5 to 21.5 |
| Cobalt (Co), % | 0 | |
| 39 to 42 |
| Iron (Fe), % | 87.3 to 90.3 | |
| 7.6 to 20 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 1.0 to 2.0 |
| Molybdenum (Mo), % | 0.85 to 1.1 | |
| 6.5 to 7.5 |
| Nickel (Ni), % | 0 to 0.4 | |
| 15 to 18 |
| Niobium (Nb), % | 0.060 to 0.1 | |
| 0 |
| Nitrogen (N), % | 0.030 to 0.070 | |
| 0 |
| Phosphorus (P), % | 0 to 0.020 | |
| 0 to 0.015 |
| Silicon (Si), % | 0.2 to 0.5 | |
| 0 to 1.2 |
| Sulfur (S), % | 0 to 0.010 | |
| 0 to 0.015 |
| Titanium (Ti), % | 0 to 0.010 | |
| 0 |
| Vanadium (V), % | 0.18 to 0.25 | |
| 0 |
| Zirconium (Zr), % | 0 to 0.010 | |
| 0 |