2218 Aluminum
2218 aluminum is a 2000-series aluminum alloy: the main alloying addition is copper, and it is formulated for primary forming into wrought products. 2218 is the Aluminum Association (AA) designation for this material. In European standards, it will be given as EN AW-2218. Additionally, the British Standard (BS) designation is 6L25. The AFNOR (French) designation is A-U4N. And the UNS number is A92218.
It has been in use since 1930, but has only received its standard designation in 1954.
The properties of 2218 aluminum include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare 2218 aluminum to: 2000-series alloys (top), all aluminum alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Brinell Hardness
95 to 110
Elastic (Young's, Tensile) Modulus
73 GPa 11 x 106 psi
Elongation at Break
6.8 to 10 %
Fatigue Strength
110 MPa 16 x 103 psi
Poisson's Ratio
0.33
Shear Modulus
27 GPa 4.0 x 106 psi
Shear Strength
210 to 250 MPa 30 to 37 x 103 psi
Tensile Strength: Ultimate (UTS)
330 to 430 MPa 48 to 63 x 103 psi
Tensile Strength: Yield (Proof)
260 to 310 MPa 37 to 45 x 103 psi
Thermal Properties
Latent Heat of Fusion
390 J/g
Maximum Temperature: Mechanical
220 °C 430 °F
Melting Completion (Liquidus)
640 °C 1180 °F
Melting Onset (Solidus)
510 °C 940 °F
Specific Heat Capacity
870 J/kg-K 0.21 BTU/lb-°F
Thermal Conductivity
140 W/m-K 81 BTU/h-ft-°F
Thermal Expansion
22 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
37 % IACS
Electrical Conductivity: Equal Weight (Specific)
110 % IACS
Otherwise Unclassified Properties
Base Metal Price
11 % relative
Density
3.1 g/cm3 190 lb/ft3
Embodied Carbon
8.2 kg CO2/kg material
Embodied Energy
150 MJ/kg 64 x 103 BTU/lb
Embodied Water
1130 L/kg 130 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
27 to 31 MJ/m3
Resilience: Unit (Modulus of Resilience)
450 to 650 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
45 points
Strength to Weight: Axial
30 to 39 points
Strength to Weight: Bending
34 to 41 points
Thermal Diffusivity
52 mm2/s
Thermal Shock Resistance
15 to 19 points
Alloy Composition
Among wrought aluminum alloys, the composition of 2218 aluminum is notable for including nickel (Ni) and containing a comparatively high amount of copper (Cu). Nickel is used to increase mechanical strength at elevated temperatures, and to reduce thermal expansion. However, it can increase susceptibility to pitting corrosion in certain alloys. Copper is used to improve strength. This comes at the cost of a decrease in corrosion resistance and weldability.
| Al | 88.8 to 93.6 | |
| Cu | 3.5 to 4.5 | |
| Ni | 1.7 to 2.3 | |
| Mg | 1.2 to 1.8 | |
| Fe | 0 to 1.0 | |
| Si | 0 to 0.9 | |
| Zn | 0 to 0.25 | |
| Mn | 0 to 0.2 | |
| Cr | 0 to 0.1 | |
| res. | 0 to 0.15 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B247: Standard Specification for Aluminum and Aluminum-Alloy Die Forgings, Hand Forgings, and Rolled Ring Forgings
Iron in Aluminium Alloys: Impurity and Alloying Element, N. A. Belov et al., 2002
Aluminum Standards and Data, Aluminum Association Inc., 2013
ASM Specialty Handbook: Aluminum and Aluminum Alloys, J. R. Davis (editor), 1993