While we associate aluminum with the production of aircraft structures, components, and systems, the truth is that this metal in its pure form is hardly ever used in these applications.
Instead, it’s aluminum alloys that are essential for building airplane and helicopter parts, since they have a high enough strength-to-weight ratio, corrosion resistance, and UV resistance for that purpose.
Pure aluminum is much too soft and lacks the right amount of tensile strength to support aircraft applications exposed to high stress, high temperature, and high corrosive environments during flight.
However, not all aluminum alloys exhibit the same properties, especially not in the amounts needed for the construction of aircraft applications.
Which brings us to the question of which aluminum alloys are aircraft grade.
You can find the answer to this question, along with other interesting facts like aluminum’s historical importance for aircraft, its benefits for aircraft manufacturing, and its future use in the aerospace and aircraft industry in the following sections.
We hope it will give you the information you need to choose the right alloy for your aircraft project.
How far back does the use of aluminum in the aircraft industry go? As far back as humans started building aircraft for flight!
Back in 1903, the Wright brothers used aluminum to build engine parts for the first-ever manned flight in human history.
As astonishing as that may seem, it’s even more remarkable that aluminum was also being used for other aircraft components before airplanes were invented.
During the late 19th century, Count Ferdinand Zeppelin used aluminum to build the frames for his “flying airship”.
Aluminum’s use at the beginning of aircraft manufacturing was a direct result of its strength-to-weight ratio (strong and light).
This was an essential combination since excessive weight and a weak structure negatively affect aircraft flight efficiency.
Heavy materials slow down and alter an aircraft’s take-off speed, flight speed, rate of climb, ceiling altitude, maneuverability, and range.
What is more, if the material being used is not strong and durable enough to withstand forces like lift, thrust, drag, and weight, as well as small objects like pebbles and rocks colliding with the aircraft’s structure during take-off and landing then severe damage can occur during flight operations.
Needless to say, this is extremely dangerous for the passengers and the flight crew.
Aluminum alloys have these properties, which, along with their high corrosion resistance, makes them the primary aircraft material used throughout the aerospace and aircraft industry’s illustrious history.
Aluminum comprises around 80% of most of today’s aircraft weight.
However, over the years the demands on aircraft materials have become more stringent.
For example, faster jets and international flights demand more durable and more fatigue-resistance aluminum derivatives (that is, alloys) to increase speed and longevity, as well as cut down on fuel costs.
In the following section, we’ll explain the benefits these derivatives have in the aircraft industry.
Aside from being the most common material used for the manufacturing of everyday products and applications, aluminum is one of the most popular materials used for aircraft structural components.
In fact, aluminum has so many beneficial properties conducive to flight that it trumps the other two materials used for building aircraft structures and parts, namely wood, and steel.
Originally, wood was used on early aircraft models but was discarded since it tended to rot and splinter, needing constant maintenance.
And while steel is still used today in some aircraft components, it is far too heavy for most aircraft applications which is why aluminum takes precedence.
The most prized benefits of aluminum include:
Ultimately, the above characteristics allow aircraft to carry more weight, use less fuel, increase safety measures, and exhibit more ergonomic properties inside the cockpit and cabin.
Of course, the benefits provided by aluminum are greatly enhanced through the use of aluminum alloys.
This is especially true when it comes to strength.
These alloys are often thirty times stronger than pure aluminum and have higher strength-to-weight ratios than steel.
Additional benefits provided by aluminum alloys include:
That being said, while many aluminum alloys exhibit much of the same properties, some do so to a higher degree and are therefore used more often in the aerospace industry.
In other words, the quality of those properties makes them more conducive to flight conditions.
In the next section, we will look at the top aluminum alloys best suited for building aircraft structures, systems, and parts.
Due to their high strength, corrosion resistance, and lightweight properties, aluminum alloys enable longer flight distances and improved flight performance.
Structures and components made from them are more durable, which lowers manufacturing costs (i.e., there are fewer material requirements).
However, the specific aluminum alloy chosen will depend on the job requirements of an aircraft application and the environment in which it must operate.
Therefore, the specific properties needed for optimal performance should be understood before alloy selection is made.
The following is a list of the most popular aluminum alloys used for aircraft manufacturing.
It includes a brief description of each alloy’s main properties and some of the aerospace applications they are commonly used for—all the basic information to make an informed decision.
Alloy 2014 is mostly used for aircraft framework projects because of its high strength and excellent machinability properties.
However, it tends to perform poorly in high-corrosive and high-stress environments and so should be avoided for designing applications working under such conditions.
Its high tensile strength, stress resistance, and ability to be heat-treated have made this alloy a popular choice for many aircraft and aerospace applications such as structures, wings, and component repair.
Alloy 3003 has good weldability and corrosion resistance making it a popular manufacturing material for many aircraft components.
It should be noted, though, that it cannot be heat-treated and therefore will not exhibit any of the benefits derived from this process.
With one of the highest fatigue strength properties among all alloy grades, alloy 5052 is the ideal choice for aircraft fuel tanks.
It also has a good degree of corrosion resistance and formability but, like alloy 3003, is not heat-treatable.
Since it has good corrosion-resistant properties and can be easily welded, alloy 6061 is primarily used for fuselage and wing components.
Alloy 6063 has a high degree of tensile strength and corrosion resistance as well as excellent extrudability properties, which makes it one of the best choices for aircraft parts that need an aesthetic design and visually appealing finishes.
With an excellent strength-to-weight ratio and the ability to be heat-treated, this alloy grade is primarily used for military aircraft components and wing skins.
Since it is one of the strongest grades of aluminum alloys and has a high degree of corrosion resistance, alloy 7068 is ideal for aircraft applications that are subjected to extreme environmental stress.
Aluminum alloy 7075 is the most widely used material for commercial airplane structures and components.
It is just as strong as steel and has high fatigue resistance and an adequate amount of corrosion resistance, making it one of the most commonly used aluminum alloys for aircraft and aerospace components, particularly gears and fuselages.
While the above list gives a good idea of which aluminum alloy is best suited for specific aircraft applications, it is still strongly advised to consult with a custom-metal parts manufacturer to narrow down which grades will work best for your aviation components and structures.
Aluminum and aluminum alloys have a long and successful history within the aerospace and aircraft industry.
Their future use looks to be just as positive and maybe even more so.
According to industry experts, the demand for aluminum in the aerospace industry is expected to double by 2025, due to the constant innovations in the industry.
One such example is the highly innovative aluminum-lithium alloy (Al-Li), a combination of aluminum and lithium.
This material brings a host of beneficial properties to aircraft design, including:
Another added benefit of Al-Li and other new-generation aluminum alloys is that they can reduce aircraft weight drastically—10% lower than composite materials.
This increases flight safety and reliability, while reducing manufacturing costs by a significant margin.
A long successful track record coupled with consistent and continuous innovations is sure to keep aluminum alloy usage in the aerospace industry at an all-time high for many years to come.
Aircraft-grade aluminum is lightweight, high strength, and corrosion-resistant.
This helps increase flight safety, speed, distance, and overall performance.
Different aircraft-grade aluminum alloys vary in properties, so it is important to know as much as you can about the different grades as possible.
Hopefully, the information within this short guide has done just that—given you enough information to select the aluminum alloy that exhibits the highest quantity of properties required by your aircraft applications.
If you need more help in making a decision, don’t hesitate to contact Bunty, a metal manufacturer who deals in custom metal parts.
We will be happy to help you choose the right material for your aircraft project.
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