Normalized SAE-AISI 4140 vs. Normalized SAE-AISI 4340
Both normalized SAE-AISI 4140 and normalized SAE-AISI 4340 are iron alloys. Both are furnished in the normalized condition. They have a very high 98% of their average alloy composition in common.
For each property being compared, the top bar is normalized SAE-AISI 4140 and the bottom bar is normalized SAE-AISI 4340.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 300 | |
| 360 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Elongation at Break, % | 18 | |
| 12 |
| Fatigue Strength, MPa | 440 | |
| 540 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 73 | |
| 73 |
| Shear Strength, MPa | 630 | |
| 770 |
| Tensile Strength: Ultimate (UTS), MPa | 1020 | |
| 1280 |
| Tensile Strength: Yield (Proof), MPa | 660 | |
| 860 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 420 | |
| 430 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1460 |
| Melting Onset (Solidus), °C | 1420 | |
| 1420 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 470 |
| Thermal Conductivity, W/m-K | 43 | |
| 44 |
| Thermal Expansion, µm/m-K | 13 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.3 | |
| 7.5 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.4 | |
| 8.6 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 2.4 | |
| 3.5 |
| Density, g/cm3 | 7.8 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 1.5 | |
| 1.7 |
| Embodied Energy, MJ/kg | 20 | |
| 22 |
| Embodied Water, L/kg | 51 | |
| 53 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 160 | |
| 140 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 1140 | |
| 1970 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 36 | |
| 45 |
| Strength to Weight: Bending, points | 29 | |
| 33 |
| Thermal Diffusivity, mm2/s | 12 | |
| 12 |
| Thermal Shock Resistance, points | 30 | |
| 38 |
Alloy Composition
| Carbon (C), % | 0.38 to 0.43 | |
| 0.38 to 0.43 |
| Chromium (Cr), % | 0.8 to 1.1 | |
| 0.7 to 0.9 |
| Iron (Fe), % | 96.8 to 97.8 | |
| 95.1 to 96.3 |
| Manganese (Mn), % | 0.75 to 1.0 | |
| 0.6 to 0.8 |
| Molybdenum (Mo), % | 0.15 to 0.25 | |
| 0.2 to 0.3 |
| Nickel (Ni), % | 0 | |
| 1.7 to 2.0 |
| Phosphorus (P), % | 0 to 0.035 | |
| 0 to 0.035 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 to 0.040 | |
| 0 to 0.040 |