Hardened SAE-AISI A8 vs. Hardened SAE-AISI H12
Both hardened SAE-AISI A8 and hardened SAE-AISI H12 are iron alloys. Both are furnished in the hardened (H) condition. Their average alloy composition is basically identical.
For each property being compared, the top bar is hardened SAE-AISI A8 and the bottom bar is hardened SAE-AISI H12.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Rockwell C Hardness | 59 | |
| 57 |
| Shear Modulus, GPa | 74 | |
| 75 |
| Tensile Strength: Ultimate (UTS), MPa | 1920 | |
| 1850 |
Thermal Properties
| Latent Heat of Fusion, J/g | 270 | |
| 270 |
| Melting Completion (Liquidus), °C | 1480 | |
| 1480 |
| Melting Onset (Solidus), °C | 1430 | |
| 1440 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 470 |
| Thermal Conductivity, W/m-K | 37 | |
| 36 |
| Thermal Expansion, µm/m-K | 12 | |
| 12 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 8.3 | |
| 8.3 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 9.5 | |
| 9.5 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 8.5 | |
| 9.0 |
| Density, g/cm3 | 7.9 | |
| 7.9 |
| Embodied Carbon, kg CO2/kg material | 2.3 | |
| 2.9 |
| Embodied Energy, MJ/kg | 31 | |
| 41 |
| Embodied Water, L/kg | 73 | |
| 76 |
Common Calculations
| PREN (Pitting Resistance) | 12 | |
| 12 |
| Stiffness to Weight: Axial, points | 14 | |
| 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 68 | |
| 65 |
| Strength to Weight: Bending, points | 44 | |
| 42 |
| Thermal Diffusivity, mm2/s | 9.9 | |
| 9.8 |
| Thermal Shock Resistance, points | 62 | |
| 60 |
Alloy Composition
| Carbon (C), % | 0.5 to 0.6 | |
| 0.3 to 0.4 |
| Chromium (Cr), % | 4.8 to 5.5 | |
| 4.8 to 5.5 |
| Copper (Cu), % | 0 to 0.25 | |
| 0 to 0.25 |
| Iron (Fe), % | 88.5 to 91.9 | |
| 87.8 to 91.7 |
| Manganese (Mn), % | 0 to 0.5 | |
| 0.2 to 0.5 |
| Molybdenum (Mo), % | 1.2 to 1.7 | |
| 1.3 to 1.8 |
| Nickel (Ni), % | 0 to 0.3 | |
| 0 to 0.3 |
| Phosphorus (P), % | 0 to 0.030 | |
| 0 to 0.030 |
| Silicon (Si), % | 0.75 to 1.1 | |
| 0.8 to 1.2 |
| Sulfur (S), % | 0 to 0.030 | |
| 0 to 0.030 |
| Tungsten (W), % | 1.0 to 1.5 | |
| 1.0 to 1.7 |
| Vanadium (V), % | 0 | |
| 0 to 0.5 |