SAE-AISI M4 Steel vs. ASTM A387 Grade 91 Class 2
Both SAE-AISI M4 steel and ASTM A387 grade 91 class 2 are iron alloys. They have 85% of their average alloy composition in common. There are 22 material properties with values for both materials. Properties with values for just one material (10, in this case) are not shown.
For each property being compared, the top bar is SAE-AISI M4 steel and the bottom bar is ASTM A387 grade 91 class 2.
Metric UnitsUS Customary Units
Mechanical Properties
| Elastic (Young's, Tensile) Modulus, GPa | 200 | |
| 190 |
| Poisson's Ratio | 0.29 | |
| 0.28 |
| Shear Modulus, GPa | 76 | |
| 75 |
| Tensile Strength: Ultimate (UTS), MPa | 770 to 2150 | |
| 670 |
Thermal Properties
| Latent Heat of Fusion, J/g | 260 | |
| 270 |
| Melting Completion (Liquidus), °C | 1610 | |
| 1460 |
| Melting Onset (Solidus), °C | 1560 | |
| 1420 |
| Specific Heat Capacity, J/kg-K | 440 | |
| 470 |
| Thermal Conductivity, W/m-K | 25 | |
| 26 |
| Thermal Expansion, µm/m-K | 12 | |
| 13 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 25 | |
| 7.0 |
| Density, g/cm3 | 8.3 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 14 | |
| 2.6 |
| Embodied Energy, MJ/kg | 210 | |
| 37 |
| Embodied Water, L/kg | 110 | |
| 88 |
Common Calculations
| PREN (Pitting Resistance) | 30 | |
| 13 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 |
| Stiffness to Weight: Bending, points | 23 | |
| 25 |
| Strength to Weight: Axial, points | 26 to 72 | |
| 24 |
| Strength to Weight: Bending, points | 23 to 45 | |
| 22 |
| Thermal Diffusivity, mm2/s | 6.9 | |
| 6.9 |
| Thermal Shock Resistance, points | 24 to 68 | |
| 19 |
Alloy Composition
| Aluminum (Al), % | 0 | |
| 0 to 0.020 |
| Carbon (C), % | 1.3 to 1.4 | |
| 0.080 to 0.12 |
| Chromium (Cr), % | 3.8 to 4.8 | |
| 8.0 to 9.5 |
| Copper (Cu), % | 0 to 0.25 | |
| 0 |
| Iron (Fe), % | 75.9 to 81.4 | |
| 87.3 to 90.3 |
| Manganese (Mn), % | 0.15 to 0.4 | |
| 0.3 to 0.6 |
| Molybdenum (Mo), % | 4.3 to 5.5 | |
| 0.85 to 1.1 |
| Nickel (Ni), % | 0 to 0.3 | |
| 0 to 0.4 |
| Niobium (Nb), % | 0 | |
| 0.060 to 0.1 |
| Nitrogen (N), % | 0 | |
| 0.030 to 0.070 |
| Phosphorus (P), % | 0 to 0.030 | |
| 0 to 0.020 |
| Silicon (Si), % | 0.2 to 0.45 | |
| 0.2 to 0.5 |
| Sulfur (S), % | 0 to 0.030 | |
| 0 to 0.010 |
| Titanium (Ti), % | 0 | |
| 0 to 0.010 |
| Tungsten (W), % | 5.3 to 6.5 | |
| 0 |
| Vanadium (V), % | 3.8 to 4.5 | |
| 0.18 to 0.25 |
| Zirconium (Zr), % | 0 | |
| 0 to 0.010 |