5251 Aluminum vs. SAE-AISI 5140 Steel
5251 aluminum belongs to the aluminum alloys classification, while SAE-AISI 5140 steel belongs to the iron 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 5251 aluminum and the bottom bar is SAE-AISI 5140 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 44 to 79 | |
| 170 to 290 |
| Elastic (Young's, Tensile) Modulus, GPa | 68 | |
| 190 |
| Elongation at Break, % | 2.0 to 19 | |
| 12 to 29 |
| Fatigue Strength, MPa | 59 to 110 | |
| 220 to 570 |
| Poisson's Ratio | 0.33 | |
| 0.29 |
| Shear Modulus, GPa | 26 | |
| 73 |
| Shear Strength, MPa | 110 to 160 | |
| 360 to 600 |
| Tensile Strength: Ultimate (UTS), MPa | 180 to 280 | |
| 560 to 970 |
| Tensile Strength: Yield (Proof), MPa | 67 to 250 | |
| 290 to 840 |
Thermal Properties
| Latent Heat of Fusion, J/g | 400 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 180 | |
| 420 |
| Melting Completion (Liquidus), °C | 650 | |
| 1460 |
| Melting Onset (Solidus), °C | 610 | |
| 1420 |
| Specific Heat Capacity, J/kg-K | 900 | |
| 470 |
| Thermal Conductivity, W/m-K | 150 | |
| 45 |
| Thermal Expansion, µm/m-K | 24 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 37 | |
| 7.2 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 120 | |
| 8.3 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 9.5 | |
| 2.1 |
| Density, g/cm3 | 2.7 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 8.5 | |
| 1.4 |
| Embodied Energy, MJ/kg | 150 | |
| 19 |
| Embodied Water, L/kg | 1180 | |
| 49 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 5.4 to 27 | |
| 76 to 180 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 33 to 450 | |
| 220 to 1880 |
| Stiffness to Weight: Axial, points | 14 | |
| 13 |
| Stiffness to Weight: Bending, points | 50 | |
| 24 |
| Strength to Weight: Axial, points | 18 to 29 | |
| 20 to 34 |
| Strength to Weight: Bending, points | 26 to 35 | |
| 19 to 28 |
| Thermal Diffusivity, mm2/s | 61 | |
| 12 |
| Thermal Shock Resistance, points | 7.9 to 13 | |
| 16 to 29 |
Alloy Composition
| Aluminum (Al), % | 95.5 to 98.2 | |
| 0 |
| Carbon (C), % | 0 | |
| 0.38 to 0.43 |
| Chromium (Cr), % | 0 to 0.15 | |
| 0.7 to 0.9 |
| Copper (Cu), % | 0 to 0.15 | |
| 0 |
| Iron (Fe), % | 0 to 0.5 | |
| 97.3 to 98.1 |
| Magnesium (Mg), % | 1.7 to 2.4 | |
| 0 |
| Manganese (Mn), % | 0.1 to 0.5 | |
| 0.7 to 0.9 |
| Phosphorus (P), % | 0 | |
| 0 to 0.035 |
| Silicon (Si), % | 0 to 0.4 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 | |
| 0 to 0.040 |
| Titanium (Ti), % | 0 to 0.15 | |
| 0 |
| Zinc (Zn), % | 0 to 0.15 | |
| 0 |
| Residuals, % | 0 to 0.15 | |
| 0 |