Aluminum 7075: The Lightweight Alloy Transforming Aerospace and Automotive Industries
The mobility industry stands before its biggest obstacle yet: creating a sustainable, CO2-free transport for people and goods. The race has been on for some time, and various companies have different solutions to make our long-desired reality. From battery-electric road-going vehicles to hybrid airplanes, the mobility landscape of the future looks vastly different from the current one.
But no matter the propulsion, the vehicles and airplanes of the future will also need to be more efficient. Engineers use various techniques to reduce the energy necessary to propel a vehicle forward, including designing the parts to be more structurally efficient, streamlining the bodies for better aerodynamics, implementing energy recovery systems, and simply making engines more efficient.
Still, the most significant contributor to lower energy consumption is lightness. And to achieve that, lighter and stiffer materials are required, which is where Aluminum 7075 comes into play. This high-strength alloy is the new kid on the block in the automotive and aerospace industries, combining strength with lightness, properties that can be further improved using heat treatment.
How Strong is Aluminum 7075?
Aluminum 7075 achieves its excellent strength by combining aluminum with zinc (5.1-6.1%) and magnesium (2.1-2.9%), which gives the alloy an excellent tensile strength of 570 MPa (83,000 psi) after a T6 heat treatment. Moreover, Aluminum 7075 has a yield strength of 505 MPa (73,200 psi) despite weighing much less than similar alloys, with a density of 2.81 g/cm3.
Due to the higher tensile strength, Aluminum 7075 has lower ductility than similar aluminum-based alloys. Still, this alloy is primarily used in high-stress applications, where this property isn’t as crucial. Besides, thanks to the addition of copper (1.2-2.0%), Aluminum 7075 is easier to machine than similar alloys, a significant advantage for the automotive and aerospace industries. Not only that, but the copper in this alloy also enhances thermal conductivity and heat resistance, making it suitable for parts that are subjected to elevated temperatures.
Corrosion Resistance of Aluminum 7075
That said, the addition of copper makes Aluminum 7075 less resistant to corrosion than similar aluminum-based alloys. Still, engineers mitigate this deficiency by using different surface treatments, such as anodizing or cladding. On the other hand, Aluminum 7075 has excellent stress-corrosion cracking resistance thanks to the high magnesium content and generally an outstanding shock and impact resistance for an aluminum-based alloy.
Main Uses of Aluminum 7075
These generally positive properties made Aluminum 7075 a widely used alloy for structural parts in the automotive and aerospace industries. Notably, you can find various transmission parts made from Aluminum 7075 in high-end sports cars and racing vehicles.
However, what was once an alloy reserved for making suspension parts in high-end sports cars (like suspension arms) has now trickled down to premium vehicles and even some economy cars. Carmakers increasingly use Aluminum 7075 to improve their products’ drivability (comfort and handling), but crucially, meet emission standards more easily.
Even truck makers, where decreasing emissions also means reducing fleet costs, use Aluminum 7075 for various structural components. Not to mention, Aluminum 7075 wheels are replacing steel wheels in many modern vehicles, significantly increasing rolling efficiency.
Aluminum 7075 also has a considerable role in the aerospace industry. The alloy is widely used to manufacture aircraft frames, structures, and wing/fuselage parts. Lately, though, Aluminum 7075 has also emerged as a great option for landing gear, where its high strength and excellent impact resistance, combined with the low density, make it a good alternative to high-strength steels and Ti-alloys.
Other parts increasingly made from Aluminum 7075 include aircraft fittings, gears and shafts, fuse parts, meter shafts and gears, missile parts, regulating valve parts, and other defense applications.
Aluminum 7075 not only improves the efficiency of automobiles and aircraft, but it is also a very sustainable alloy in its own right. Notably, Aluminum 7075 is easily recyclable, which is vital for sustainability. But even more important is that it requires less energy to produce and recycle Aluminum 7075 than new aluminum. Therefore, expect to see Aluminum 7075 in even more applications soon, especially with EVs, eVTOLs, and hybrid aircraft on the horizon.
Can You Weld Aluminum 7075?
Aluminum 7075 is only a part of the sustainability story; other aluminum-based alloys will also be increasingly used in the automotive and aerospace industries, aiming to create a more sustainable transport for everyone.
For instance, Aluminum 7075 can be challenging to weld, and manufacturers rarely weld parts made from this alloy. That is because its chemical composition makes it susceptible to cracking and weakening in the heat-affected zones during the welding process. Hence, for applications that require welding, Aluminum 6061 is the preferred option. Furthermore, Aluminum 2024 offers better ductility than Aluminum 7075, while Aluminum 5052 offers higher corrosion resistance.
All these alloys, along with the increased use of composite materials, will make future vehicles lighter, more efficient, and safer for everyone. Critically, they will bring us to a more sustainable future more quickly and make our environment better for everyone.