Aluminum plate is a versatile metal with a wide range of properties that make it ideal for many applications. In the aerospace industry, aluminum plate is used in a variety of components, including aircraft structures, marine components, and jet engine parts.
Two of the most common types of aluminum plates used in aircraft applications are the 7xxx and 2xxx series. These two series have different alloying elements, which give them different properties.
Alloying Elements: Defining Dissimilarity
The main difference between the 7xxx and 2xxx series is the alloying element. 7xxx series aluminum plates are alloyed with zinc, while 2xxx series aluminum plates are alloyed with copper.
Zinc is a stronger alloying element than copper, so 7xxx series aluminum plates are stronger than 2xxx series aluminum plates. Zinc also improves the corrosion resistance of aluminum, so 7xxx series aluminum plates are more resistant to corrosion than 2xxx series aluminum plates.
Copper is a more ductile alloying element than zinc, so 2xxx series aluminum plates are more ductile than 7xxx series aluminum plates. Ductility is the ability of a material to be deformed without breaking. This makes 2xxx series aluminum plates more suitable for applications where they need to be bent or shaped.
Physical Properties: Strength, Ductility, and Corrosion Resistance
The different alloying elements in the 7xxx and 2xxx series give rise to different physical properties in the two types of aluminum plates.
Here is a table summarizing the key physical properties of 7xxx and 2xxx series aerospace aluminum plate:
| Property | 7xxx series | 2xxx series |
| Density | 2.81 g/cm³ | 2.70 g/cm³ |
| Melting point | 651 °C | 658 °C |
| Specific heat | 0.903 J/g/°C | 0.921 J/g/°C |
| Thermal conductivity | 237 W/(m·K) | 205 W/(m·K) |
| Young’s modulus | 70 GPa | 110 GPa |
| Poisson’s ratio | 0.33 | 0.35 |
As you can see, 7xxx series aluminum plates have a higher density, specific heat, and thermal conductivity than 2xxx series aluminum plates. However, 2xxx series aluminum plates have a higher melting point and Young’s modulus than 7xxx series aluminum plates.
Applications: Tailoring Selection to Purpose
The different properties of the 7xxx and 2xxx series make them suitable for different applications.
7xxx series aluminum plates are often used in applications where high strength and corrosion resistance are required, such as:
- Aircraft structures: 7xxx series aluminum plates are used in a variety of aircraft structures, including fuselages, wings, and tails. These plates are used because they offer a good combination of strength, corrosion resistance, and formability.
- Marine components: 7xxx series aluminum plates are also used in marine components, such as hulls, decks, and propellers. These plates are used because they are resistant to seawater corrosion and can withstand the harsh marine environment.
- Jet engine parts: 7xxx series aluminum plates are used in a variety of jet engine parts, such as turbine blades and compressor disks. These plates are used because they can withstand the high temperatures and stresses of jet engine operation.
- Chemical processing equipment: 7xxx series aluminum plates are used in chemical processing equipment, such as reactors and tanks. These plates are used because they are resistant to corrosion by chemicals.
- Food processing equipment: 7xxx series aluminum plates are also used in food processing equipment, such as conveyor belts and food mixers. These plates are used because they are resistant to corrosion by food products.
2xxx series aluminum plates are often used in applications where good formability and weldability are required, such as:
- Aircraft skin panels: 2xxx series aluminum plates are used in aircraft skin panels because they are easy to form and can be bonded to other materials. These plates are also resistant to fatigue, which makes them suitable for applications where the panels are subjected to repeated loading.
- Landing gear components: 2xxx series aluminum plates are used in landing gear components, such as struts and shock absorbers. These plates are used because they are strong and ductile, which allows them to withstand the high loads and shocks experienced during landing.
- Structural components for cars and trucks: 2xxx series aluminum plates are also used in structural components for cars and trucks, such as chassis rails and suspension components. These plates are used because they are lightweight and strong, which helps to improve fuel efficiency and reduce emissions.
- Medical implants: 2xxx series aluminum plates are also used in medical implants, such as hip replacements and knee replacements. These plates are used because they are biocompatible, which means that they are not rejected by the body.
Conclusion
The 7xxx and 2xxx series are two of the most common types of aluminum plates used in aerospace applications. The different alloying elements in these two series give rise to different properties, which make them suitable for different applications.
The engineer will need to consider the required strength, corrosion resistance, ductility, formability, and weldability to make the best selection of aluminum plate for a particular application.
