SAE-AISI 4340 Steel vs. 4115 Aluminum
SAE-AISI 4340 steel belongs to the iron alloys classification, while 4115 aluminum belongs to the aluminum alloys. Please note that the two materials have significantly dissimilar densities. This means that additional care is required when interpreting the data, because some material properties are based on units of mass, while others are based on units of area or volume.
For each property being compared, the top bar is SAE-AISI 4340 steel and the bottom bar is 4115 aluminum.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 210 to 360 | |
| 38 to 68 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 70 |
| Elongation at Break, % | 12 to 22 | |
| 1.1 to 11 |
| Fatigue Strength, MPa | 330 to 740 | |
| 39 to 76 |
| Poisson's Ratio | 0.29 | |
| 0.33 |
| Shear Modulus, GPa | 73 | |
| 26 |
| Shear Strength, MPa | 430 to 770 | |
| 71 to 130 |
| Tensile Strength: Ultimate (UTS), MPa | 690 to 1280 | |
| 120 to 220 |
| Tensile Strength: Yield (Proof), MPa | 470 to 1150 | |
| 39 to 190 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 420 |
| Maximum Temperature: Mechanical, °C | 430 | |
| 160 |
| Melting Completion (Liquidus), °C | 1460 | |
| 640 |
| Melting Onset (Solidus), °C | 1420 | |
| 590 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 900 |
| Thermal Conductivity, W/m-K | 44 | |
| 160 |
| Thermal Expansion, µm/m-K | 13 | |
| 23 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.5 | |
| 41 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.6 | |
| 140 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 3.5 | |
| 9.5 |
| Density, g/cm3 | 7.8 | |
| 2.7 |
| Embodied Carbon, kg CO2/kg material | 1.7 | |
| 8.1 |
| Embodied Energy, MJ/kg | 22 | |
| 150 |
| Embodied Water, L/kg | 53 | |
| 1160 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 79 to 170 | |
| 2.1 to 10 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 590 to 3490 | |
| 11 to 270 |
| Stiffness to Weight: Axial, points | 13 | |
| 14 |
| Stiffness to Weight: Bending, points | 24 | |
| 50 |
| Strength to Weight: Axial, points | 24 to 45 | |
| 12 to 23 |
| Strength to Weight: Bending, points | 22 to 33 | |
| 20 to 30 |
| Thermal Diffusivity, mm2/s | 12 | |
| 66 |
| Thermal Shock Resistance, points | 20 to 38 | |
| 5.2 to 9.9 |
Alloy Composition
| Aluminum (Al), % | 0 | |
| 94.6 to 97.4 |
| Carbon (C), % | 0.38 to 0.43 | |
| 0 |
| Chromium (Cr), % | 0.7 to 0.9 | |
| 0 |
| Copper (Cu), % | 0 | |
| 0.1 to 0.5 |
| Iron (Fe), % | 95.1 to 96.3 | |
| 0 to 0.7 |
| Magnesium (Mg), % | 0 | |
| 0.1 to 0.5 |
| Manganese (Mn), % | 0.6 to 0.8 | |
| 0.6 to 1.2 |
| Molybdenum (Mo), % | 0.2 to 0.3 | |
| 0 |
| Nickel (Ni), % | 1.7 to 2.0 | |
| 0 |
| Phosphorus (P), % | 0 to 0.035 | |
| 0 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 1.8 to 2.2 |
| Sulfur (S), % | 0 to 0.040 | |
| 0 |
| Zinc (Zn), % | 0 | |
| 0 to 0.2 |
| Residuals, % | 0 | |
| 0 to 0.15 |