Hardened SAE-AISI A4 vs. Hardened SAE-AISI O7
Both hardened SAE-AISI A4 and hardened SAE-AISI O7 are iron alloys. Both are furnished in the hardened (H) condition. They have a very high 97% of their average alloy composition in common.
For each property being compared, the top bar is hardened SAE-AISI A4 and the bottom bar is hardened SAE-AISI O7.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Rockwell C Hardness | 63 | |
| 65 |
| Shear Modulus, GPa | 73 | |
| 73 |
| Tensile Strength: Ultimate (UTS), MPa | 2050 | |
| 2110 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 250 |
| Melting Completion (Liquidus), °C | 1450 | |
| 1480 |
| Melting Onset (Solidus), °C | 1410 | |
| 1430 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 470 |
| Thermal Conductivity, W/m-K | 40 | |
| 41 |
| Thermal Expansion, µm/m-K | 12 | |
| 12 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.4 | |
| 7.6 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.6 | |
| 8.7 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 3.9 | |
| 6.0 |
| Density, g/cm3 | 7.8 | |
| 7.9 |
| Embodied Carbon, kg CO2/kg material | 1.8 | |
| 2.3 |
| Embodied Energy, MJ/kg | 24 | |
| 33 |
| Embodied Water, L/kg | 59 | |
| 52 |
Common Calculations
| PREN (Pitting Resistance) | 5.3 | |
| 3.6 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 73 | |
| 74 |
| Strength to Weight: Bending, points | 46 | |
| 46 |
| Thermal Diffusivity, mm2/s | 11 | |
| 11 |
| Thermal Shock Resistance, points | 67 | |
| 70 |
Alloy Composition
| Carbon (C), % | 1.0 to 1.1 | |
| 1.1 to 1.3 |
| Chromium (Cr), % | 0.9 to 2.2 | |
| 0.35 to 0.85 |
| Copper (Cu), % | 0 to 0.25 | |
| 0 to 0.25 |
| Iron (Fe), % | 92 to 95.5 | |
| 92.9 to 97.6 |
| Manganese (Mn), % | 1.8 to 2.2 | |
| 0 to 1.0 |
| Molybdenum (Mo), % | 0.9 to 1.4 | |
| 0 to 0.3 |
| Nickel (Ni), % | 0 to 0.3 | |
| 0 to 0.3 |
| Phosphorus (P), % | 0 to 0.030 | |
| 0 to 0.030 |
| Silicon (Si), % | 0 to 0.5 | |
| 0 to 0.6 |
| Sulfur (S), % | 0 to 0.030 | |
| 0 to 0.030 |
| Tungsten (W), % | 0 | |
| 1.0 to 2.0 |
| Vanadium (V), % | 0 | |
| 0 to 0.4 |