2218 Aluminum vs. SAE-AISI 81B45 Steel
2218 aluminum belongs to the aluminum alloys classification, while SAE-AISI 81B45 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 2218 aluminum and the bottom bar is SAE-AISI 81B45 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 95 to 110 | |
| 160 to 200 |
| Elastic (Young's, Tensile) Modulus, GPa | 73 | |
| 190 |
| Elongation at Break, % | 6.8 to 10 | |
| 12 to 24 |
| Fatigue Strength, MPa | 110 | |
| 250 to 350 |
| Poisson's Ratio | 0.33 | |
| 0.29 |
| Shear Modulus, GPa | 27 | |
| 73 |
| Shear Strength, MPa | 210 to 250 | |
| 340 to 400 |
| Tensile Strength: Ultimate (UTS), MPa | 330 to 430 | |
| 540 to 670 |
| Tensile Strength: Yield (Proof), MPa | 260 to 310 | |
| 350 to 560 |
Thermal Properties
| Latent Heat of Fusion, J/g | 390 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 220 | |
| 410 |
| Melting Completion (Liquidus), °C | 640 | |
| 1460 |
| Melting Onset (Solidus), °C | 510 | |
| 1420 |
| Specific Heat Capacity, J/kg-K | 870 | |
| 470 |
| Thermal Conductivity, W/m-K | 140 | |
| 40 |
| Thermal Expansion, µm/m-K | 22 | |
| 12 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 37 | |
| 7.2 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 110 | |
| 8.3 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 11 | |
| 2.3 |
| Density, g/cm3 | 3.1 | |
| 7.8 |
| Embodied Carbon, kg CO2/kg material | 8.2 | |
| 1.5 |
| Embodied Energy, MJ/kg | 150 | |
| 20 |
| Embodied Water, L/kg | 1130 | |
| 49 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 27 to 31 | |
| 77 to 110 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 450 to 650 | |
| 320 to 840 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 45 | |
| 24 |
| Strength to Weight: Axial, points | 30 to 39 | |
| 19 to 24 |
| Strength to Weight: Bending, points | 34 to 41 | |
| 19 to 22 |
| Thermal Diffusivity, mm2/s | 52 | |
| 11 |
| Thermal Shock Resistance, points | 15 to 19 | |
| 17 to 21 |
Alloy Composition
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| Aluminum (Al), % | 88.8 to 93.6 | |
| 0 |
| Boron (B), % | 0 | |
| 0.00050 to 0.0030 |
| Carbon (C), % | 0 | |
| 0.43 to 0.48 |
| Chromium (Cr), % | 0 to 0.1 | |
| 0.35 to 0.55 |
| Copper (Cu), % | 3.5 to 4.5 | |
| 0 |
| Iron (Fe), % | 0 to 1.0 | |
| 97 to 98 |
| Magnesium (Mg), % | 1.2 to 1.8 | |
| 0 |
| Manganese (Mn), % | 0 to 0.2 | |
| 0.75 to 1.0 |
| Molybdenum (Mo), % | 0 | |
| 0.080 to 0.15 |
| Nickel (Ni), % | 1.7 to 2.3 | |
| 0.2 to 0.4 |
| Phosphorus (P), % | 0 | |
| 0 to 0.035 |
| Silicon (Si), % | 0 to 0.9 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 | |
| 0 to 0.040 |
| Zinc (Zn), % | 0 to 0.25 | |
| 0 |
| Residuals, % | 0 to 0.15 | |
| 0 |