Aluminum vs. Stainless Steel in Aerospace


Aluminum was once the primary material used in aerospace applications. However, in modern jet aircraft, it accounts for just 20% of the construction. However, because of the demand for lighter weight aircraft, composite materials such as carbon-reinforced polymers and honeycomb materials continue to increase in usage across the modern aerospace and aviation industries. Further requirements such as the need to withstand high temperatures, pressures, and corrosion have paved the way for other materials once considered impossible for use in aerospace. One such material is stainless steel, which has seen increased usage in newer aircraft components.This blog will explain uses of and differences between aluminum and stainless steel in modern aircraft.

Aluminum is a silvery-white, soft, non-magnetic and ductile metal. It is highly conductive and distinguished by its low density and ability to resist corrosion through the phenomenon of passivation. In addition to the aerospace industry, aluminum and its alloys are used in the transportation, building & construction, packaging, electricity, household, and machinery & equipment industries. It is the most widely used non-ferrous metal. In 2016, global production of aluminum reached nearly 60 million metric tons. Aluminum is nearly always alloyed, which significantly improves its mechanical properties, especially when tempered.

Despite its seemingly waning popularity, aluminum is still widely used throughout aircraft for a broad range of components. For many applications, aluminum is still the strongest and most lightweight material available. It can be machined easily thanks to its high ductility, and is relatively cheap in comparison to alternatives like composites or titanium. Additionally, aluminum can be strengthened further by alloying it with other metals such as magnesium, zinc, and manganese, or by subjecting it to cold or heat treatment. When exposed to air, aluminum’s tight chemical oxide bond causes it to be sealed off from the environment. This feature makes it extremely resistant to corrosion.

Aluminum can also be finished in a wide range of ways to serve an array of functions, and its high electrical conductivity makes it an ideal raw material for many different applications. There are three types of aluminum alloy used in the fabrication of aerospace parts: aluminum alloy 7075, aluminum alloy 7475-02, and aluminum alloy 6061. 7075 is a combination of aluminum and zinc, and is the most commonly used alloy in aerospace applications due to its excellent mechanical properties, ductility, strength, and resistance to fatigue. 7475-02 is a combination of aluminum, zinc, silicon, and chromium, and 6061 comprises aluminum, magnesium, and silicon. Which alloy is needed depends entirely on the intended application of the end part. While many aluminum aircraft parts are purely cosmetic, some are critical to the function of the aircraft and must have specific characteristics.

A common type of aluminum alloy used in the aerospace industry is aluminum-scandium. The addition of scandium to aluminum bolsters the metal’s strength and ability to resist heat. The use of aluminum-scandium can also increase fuel efficiency. As it is an alternative to denser materials such as steel and titanium, replacement of these with lighter aluminum-scandium leads to weight reduction which in turn provides greater fuel efficiency.

Stainless steel refers to a family of iron-based alloys that contain a minimum of 11% chromium, a compound that prevents iron from corroding, as well as providing resistance to heat. Different types of stainless steel include the elements nitrogen, aluminum, silicon, sulfur, titanium, nickel, copper, selenium, niobium, and molybdenum. Types of stainless steel are graded and designated by a three-digit number. There are more than 150 grades of stainless steel, though only about one tenth are used regularly. Stainless steel’s resistance to ferric oxide formation stems from the presence of chromium within the alloy, which creates a passive film that protects the material from corrosion. In fact, this film can actually self-heal when exposed to oxygen.

Resistance to corrosion and staining, low maintenance, and familiar luster make stainless steel a popular material in applications where both strength and corrosion resistance are required. Furthermore, stainless steel can be shaped into sheets, plates, bars, wire, and tubing, making them useful for a variety of applications. There are five main families of stainless steel, primarily classified by their crystalline structures. These families are austentistic, ferritic, martensitic, duplex, and precipitation hardening stainless steels.

As stated above, stainless steel is an alloy made through the combination of steel and chromium. The strength of stainless steel is directly linked to the amount of chromium within the alloy. The higher chromium volume, the stronger the steel. Although it is stronger than aluminum, stainless steel is also heavier, preventing it from being widely used in aerospace applications. Nevertheless, stainless steel parts have two significant advantages over aluminum. First, stainless-steel is highly resistant to corrosion. Second, it is stronger and more resistant to wear and tear. Stainless steel parts can handle stress, vibration, scratches, impact, and damage much better than aluminum parts.

Stainless steel alloys are seeing increasing use in aircraft components that require great strength and can withstand the extra weight. The high corrosion and temperature resistances found in stainless steel make it a suitable choice for a wide range of aerospace parts such as actuators, fasteners, and landing gear components. Whether you are in search of high quality aluminum or stainless steel aircraft components, ASAP Buying has the parts you need.

At ASAP Buying, owned and operated by ASAP Semiconductor, we can help you find all types of aluminum and stainless steel aircraft parts and deliver them with short lead times and competitive prices. We’re always available and ready to help you find all the parts and equipment you need, 24/7-365. ASAP Buying is an AS9120B, ISO 9001:2015, and FAA AC 00-56B accredited business, as well as the only independent distributor with a No China Sourcing Pledge, ensuring each part you purchase from is fully traceable or comes directly from the manufacturer. For a quick and competitive quote, email us at sales@asapbuying.com or call us at +1-509-449-7700. Our team of dedicated account managers is standing by and will reach out to you in 15 minutes or less.


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September 28, 2021
April 20, 2021

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