1 November 2021 2000 Series Aluminum Alloy
2218 Aluminum Alloy Plate
2218 aluminium alloy is an alloy in the wrought aluminium-copper family (2000 or 2xxx series). It is one of the most complex grades in the 2000 series, with at least 88.4% aluminium by weight. Unlike most other aluminium-copper alloys, 2218 is a high work-ability alloy, with relatively low for 2xxx series alloy yield strength of 255 MPa. Despite being highly alloyed, it have a good corrosion and oxidation resistance due sacrificial anode formed by magnesium inclusions, similar to marine-grade 5xxx series alloys. Although 2218 is wrought alloy, owing to granular structure it can be used in casting and been precisely machined after casting. It is easy to weld, coat, or glue.
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.
Good workability, thermal conductivity and dimensional stability make 2218 alloy a material of choice whenever high-precision parts subject to thermal shocks (especially piston engine cylinders and cylinder heads) are needed.
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.
2218 alloy can be heat treated to increase tensile strength in expense of workability, with most common grades been F, T61, T71 and T72. Alternative names for 2218 alloy are A2218 and A92218.
Chemical Composition:
| Component Elements | Metric | English | Comments |
|---|---|---|---|
| Aluminum, Al | 88.8 - 93.6 % | 88.8 - 93.6 % | As remainder |
| Chromium, Cr | <= 0.10 % | <= 0.10 % | |
| Copper, Cu | 3.5 - 4.5 % | 3.5 - 4.5 % | |
| Iron, Fe | <= 1.0 % | <= 1.0 % | |
| Magnesium, Mg | 1.2 - 1.8 % | 1.2 - 1.8 % | |
| Manganese, Mn | <= 0.20 % | <= 0.20 % | |
| Nickel, Ni | 1.7 - 2.3 % | 1.7 - 2.3 % | |
| Other, each | <= 0.05 % | <= 0.05 % | |
| Other, total | <= 0.15 % | <= 0.15 % | |
| Silicon, Si | <= 0.90 % | <= 0.90 % | |
| Zinc, Zn | <= 0.25 % | <= 0.25 % |
Mechanical Properties:
| Thermal Properties | Metric | English | Comments |
|---|---|---|---|
| CTE, linear | 20.7 µm/m-°C @Temperature -50.0 - 20.0 °C | 11.5 µin/in-°F @Temperature -58.0 - 68.0 °F | |
| 22.3 µm/m-°C @Temperature 20.0 - 100 °C | 12.4 µin/in-°F @Temperature 68.0 - 212 °F | AA; Typical; average over range | |
| 22.4 µm/m-°C @Temperature 20.0 - 100 °C | 12.4 µin/in-°F @Temperature 68.0 - 212 °F | ||
| 23.3 µm/m-°C @Temperature 20.0 - 200 °C | 12.9 µin/in-°F @Temperature 68.0 - 392 °F | ||
| 24.2 µm/m-°C @Temperature 20.0 - 300 °C | 13.4 µin/in-°F @Temperature 68.0 - 572 °F | ||
| Specific Heat Capacity | 0.880 J/g-°C | 0.210 BTU/lb-°F | Estimated from trends in similar Al alloys. |
| Thermal Conductivity | 155 W/m-K | 1080 BTU-in/hr-ft²-°F | |
| Melting Point | 502 - 638 °C | 935 - 1180 °F | AA; Typical range based on typical composition for wrought products >= 1/4 in. thickness. Eutectic melting is not eliminated by homogenization. |
| Solidus | 502 °C | 935 °F | AA; Typical |
| Liquidus | 638 °C | 1180 °F | AA; Typical |
Thermal Properties
| Properties | Conditions | ||
|---|---|---|---|
| T (°C) | Treatment | ||
| Thermal conductivity | 148 W/mK | 25 | T61 |
| Thermal expansion | 22.3 x 10-6/°C | 20-100 | - |
Application:
Aluminium / aluminum 2218 alloy is chiefly used in areas such as electrical conductors and transport.