Hardened SAE-AISI H21 vs. Hardened SAE-AISI O7
Both hardened SAE-AISI H21 and hardened SAE-AISI O7 are iron alloys. Both are furnished in the hardened (H) condition. They have a moderately high 94% of their average alloy composition in common. There are 23 material properties with values for both materials. Properties with values for just one material (2, in this case) are not shown.
For each property being compared, the top bar is hardened SAE-AISI H21 and the bottom bar is hardened SAE-AISI O7.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 200 | |
| 190 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Rockwell C Hardness | 55 | |
| 65 |
| Shear Modulus, GPa | 76 | |
| 73 |
| Tensile Strength: Ultimate (UTS), MPa | 1790 | |
| 2110 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 250 |
| Melting Completion (Liquidus), °C | 1630 | |
| 1480 |
| Melting Onset (Solidus), °C | 1580 | |
| 1430 |
| Specific Heat Capacity, J/kg-K | 440 | |
| 470 |
| Thermal Conductivity, W/m-K | 27 | |
| 41 |
| Thermal Expansion, µm/m-K | 11 | |
| 12 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 23 | |
| 6.0 |
| Density, g/cm3 | 8.5 | |
| 7.9 |
| Embodied Carbon, kg CO2/kg material | 4.5 | |
| 2.3 |
| Embodied Energy, MJ/kg | 68 | |
| 33 |
| Embodied Water, L/kg | 72 | |
| 52 |
Common Calculations
| PREN (Pitting Resistance) | 19 | |
| 3.6 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 23 | |
| 24 |
| Strength to Weight: Axial, points | 58 | |
| 74 |
| Strength to Weight: Bending, points | 38 | |
| 46 |
| Thermal Diffusivity, mm2/s | 7.1 | |
| 11 |
| Thermal Shock Resistance, points | 59 | |
| 70 |
Alloy Composition
| Carbon (C), % | 0.28 to 0.36 | |
| 1.1 to 1.3 |
| Chromium (Cr), % | 3.0 to 3.8 | |
| 0.35 to 0.85 |
| Copper (Cu), % | 0 to 0.25 | |
| 0 to 0.25 |
| Iron (Fe), % | 87.6 to 93.8 | |
| 92.9 to 97.6 |
| Manganese (Mn), % | 0.15 to 0.4 | |
| 0 to 1.0 |
| Molybdenum (Mo), % | 0 | |
| 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), % | 0.15 to 0.5 | |
| 0 to 0.6 |
| Sulfur (S), % | 0 to 0.030 | |
| 0 to 0.030 |
| Tungsten (W), % | 8.5 to 10 | |
| 1.0 to 2.0 |
| Vanadium (V), % | 0.3 to 0.6 | |
| 0 to 0.4 |