Hardened SAE-AISI H21 vs. Hardened SAE-AISI M2
Both hardened SAE-AISI H21 and hardened SAE-AISI M2 are iron alloys. Both are furnished in the hardened (H) condition. They have a moderately high 92% of their average alloy composition in common.
For each property being compared, the top bar is hardened SAE-AISI H21 and the bottom bar is hardened SAE-AISI M2.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 200 | |
| 200 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Rockwell C Hardness | 55 | |
| 66 |
| Shear Modulus, GPa | 76 | |
| 77 |
| Tensile Strength: Ultimate (UTS), MPa | 1790 | |
| 2150 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 260 |
| Melting Completion (Liquidus), °C | 1630 | |
| 1610 |
| Melting Onset (Solidus), °C | 1580 | |
| 1570 |
| Specific Heat Capacity, J/kg-K | 440 | |
| 440 |
| Thermal Conductivity, W/m-K | 27 | |
| 22 |
| Thermal Expansion, µm/m-K | 11 | |
| 10 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 23 | |
| 24 |
| Density, g/cm3 | 8.5 | |
| 8.4 |
| Embodied Carbon, kg CO2/kg material | 4.5 | |
| 8.8 |
| Embodied Energy, MJ/kg | 68 | |
| 130 |
| Embodied Water, L/kg | 72 | |
| 98 |
Common Calculations
| PREN (Pitting Resistance) | 19 | |
| 31 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 23 | |
| 23 |
| Strength to Weight: Axial, points | 58 | |
| 71 |
| Strength to Weight: Bending, points | 38 | |
| 44 |
| Thermal Diffusivity, mm2/s | 7.1 | |
| 5.9 |
| Thermal Shock Resistance, points | 59 | |
| 76 |
Alloy Composition
| Carbon (C), % | 0.28 to 0.36 | |
| 0.78 to 1.1 |
| Chromium (Cr), % | 3.0 to 3.8 | |
| 3.8 to 4.5 |
| Copper (Cu), % | 0 to 0.25 | |
| 0 to 0.25 |
| Iron (Fe), % | 87.6 to 93.8 | |
| 78.5 to 83.4 |
| Manganese (Mn), % | 0.15 to 0.4 | |
| 0.15 to 0.4 |
| Molybdenum (Mo), % | 0 | |
| 4.5 to 5.5 |
| 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 | |
| 0.2 to 0.45 |
| Sulfur (S), % | 0 to 0.030 | |
| 0 to 0.030 |
| Tungsten (W), % | 8.5 to 10 | |
| 5.5 to 6.8 |
| Vanadium (V), % | 0.3 to 0.6 | |
| 1.8 to 2.2 |