SAE-AISI M4 Steel vs. SAE-AISI M3 Class 2 Steel
Both SAE-AISI M4 steel and SAE-AISI M3 class 2 steel are iron alloys. Their average alloy composition is basically identical.
For each property being compared, the top bar is SAE-AISI M4 steel and the bottom bar is SAE-AISI M3 class 2 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 200 | |
| 200 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 76 | |
| 77 |
| Tensile Strength: Ultimate (UTS), MPa | 770 to 2150 | |
| 770 to 2210 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 260 |
| Melting Completion (Liquidus), °C | 1610 | |
| 1620 |
| Melting Onset (Solidus), °C | 1560 | |
| 1570 |
| Specific Heat Capacity, J/kg-K | 440 | |
| 440 |
| Thermal Conductivity, W/m-K | 25 | |
| 26 |
| Thermal Expansion, µm/m-K | 12 | |
| 12 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 25 | |
| 25 |
| Density, g/cm3 | 8.3 | |
| 8.3 |
| Embodied Carbon, kg CO2/kg material | 14 | |
| 12 |
| Embodied Energy, MJ/kg | 210 | |
| 180 |
| Embodied Water, L/kg | 110 | |
| 110 |
Common Calculations
| PREN (Pitting Resistance) | 30 | |
| 33 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 23 | |
| 23 |
| Strength to Weight: Axial, points | 26 to 72 | |
| 26 to 74 |
| Strength to Weight: Bending, points | 23 to 45 | |
| 22 to 45 |
| Thermal Diffusivity, mm2/s | 6.9 | |
| 7.2 |
| Thermal Shock Resistance, points | 24 to 68 | |
| 24 to 69 |
Alloy Composition
| Carbon (C), % | 1.3 to 1.4 | |
| 1.2 to 1.3 |
| Chromium (Cr), % | 3.8 to 4.8 | |
| 3.8 to 4.5 |
| Copper (Cu), % | 0 to 0.25 | |
| 0 to 0.25 |
| Iron (Fe), % | 75.9 to 81.4 | |
| 75.8 to 82.3 |
| Manganese (Mn), % | 0.15 to 0.4 | |
| 0.15 to 0.4 |
| Molybdenum (Mo), % | 4.3 to 5.5 | |
| 4.8 to 6.5 |
| Nickel (Ni), % | 0 to 0.3 | |
| 0 to 0.3 |
| Phosphorus (P), % | 0 to 0.030 | |
| 0 to 0.030 |
| Silicon (Si), % | 0.2 to 0.45 | |
| 0.2 to 0.45 |
| Sulfur (S), % | 0 to 0.030 | |
| 0 to 0.030 |
| Tungsten (W), % | 5.3 to 6.5 | |
| 5.0 to 6.8 |
| Vanadium (V), % | 3.8 to 4.5 | |
| 2.8 to 3.8 |