ASTM A387 Grade 91 Class 2 vs. SAE-AISI A8 Steel
Both ASTM A387 grade 91 class 2 and SAE-AISI A8 steel are iron alloys. They have a very high 96% of their average alloy composition in common. There are 24 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 ASTM A387 grade 91 class 2 and the bottom bar is SAE-AISI A8 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Poisson's Ratio | 0.28 | |
| 0.29 |
| Shear Modulus, GPa | 75 | |
| 74 |
| Tensile Strength: Ultimate (UTS), MPa | 670 | |
| 700 to 1920 |
Thermal Properties
| Latent Heat of Fusion, J/g | 270 | |
| 270 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1480 |
| Melting Onset (Solidus), °C | 1420 | |
| 1430 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 470 |
| Thermal Conductivity, W/m-K | 26 | |
| 37 |
| Thermal Expansion, µm/m-K | 13 | |
| 12 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 8.9 | |
| 8.3 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 10 | |
| 9.5 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 7.0 | |
| 8.5 |
| Density, g/cm3 | 7.8 | |
| 7.9 |
| Embodied Carbon, kg CO2/kg material | 2.6 | |
| 2.3 |
| Embodied Energy, MJ/kg | 37 | |
| 31 |
| Embodied Water, L/kg | 88 | |
| 73 |
Common Calculations
| PREN (Pitting Resistance) | 13 | |
| 12 |
| Stiffness to Weight: Axial, points | 14 | |
| 14 |
| Stiffness to Weight: Bending, points | 25 | |
| 24 |
| Strength to Weight: Axial, points | 24 | |
| 25 to 68 |
| Strength to Weight: Bending, points | 22 | |
| 22 to 44 |
| Thermal Diffusivity, mm2/s | 6.9 | |
| 9.9 |
| Thermal Shock Resistance, points | 19 | |
| 22 to 62 |
Alloy Composition
| Aluminum (Al), % | 0 to 0.020 | |
| 0 |
| Carbon (C), % | 0.080 to 0.12 | |
| 0.5 to 0.6 |
| Chromium (Cr), % | 8.0 to 9.5 | |
| 4.8 to 5.5 |
| Copper (Cu), % | 0 | |
| 0 to 0.25 |
| Iron (Fe), % | 87.3 to 90.3 | |
| 88.5 to 91.9 |
| Manganese (Mn), % | 0.3 to 0.6 | |
| 0 to 0.5 |
| Molybdenum (Mo), % | 0.85 to 1.1 | |
| 1.2 to 1.7 |
| Nickel (Ni), % | 0 to 0.4 | |
| 0 to 0.3 |
| Niobium (Nb), % | 0.060 to 0.1 | |
| 0 |
| Nitrogen (N), % | 0.030 to 0.070 | |
| 0 |
| Phosphorus (P), % | 0 to 0.020 | |
| 0 to 0.030 |
| Silicon (Si), % | 0.2 to 0.5 | |
| 0.75 to 1.1 |
| Sulfur (S), % | 0 to 0.010 | |
| 0 to 0.030 |
| Titanium (Ti), % | 0 to 0.010 | |
| 0 |
| Tungsten (W), % | 0 | |
| 1.0 to 1.5 |
| Vanadium (V), % | 0.18 to 0.25 | |
| 0 |
| Zirconium (Zr), % | 0 to 0.010 | |
| 0 |