Why You Should Use Stainless Steel for Aerospace Applications

In American Manufacturing

Marlin Steel on July 25, 2019

Exposed aircraft engine that has stainless steel and other metal alloys.When creating parts for aerospace applications, there are many considerations to make. For example, the shape, weight, and durability of a part can all affect the aircraft’s flight worthiness. If a plane is too heavy, it will need extra thrust to achieve liftoff and maintain altitude—increasing fuel consumption. If the superstructure of a plane is too weak, on the other hand, it could fail mid-flight and put the occupants’ lives at risk.

For years, the go-to material for aerospace applications was aluminum. However, in recent years, aerospace manufacturers have started investigating alternatives to aluminum, one of them being aerospace grade stainless steel.

Comparing Aluminum Vs Stainless Steel for Aerospace Applications

Aluminum has long been the “go-to” material for making aircraft components because of its combination of high tensile strength, relatively light weight per cubic centimeter (approximately 2.7 g/cm3), and easy machinability in addition to strong corrosion resistance. Also, as an atomic element, pure aluminum has a relatively low cost compared to many alloys (though this varies).

The ultimate tensile strength (UTS) of aluminum can vary based on what the material is alloyed with. However, aluminum 6061-T6—which is over 95% pure aluminum—has a UTS of 310 MPa (45,000 psi) according to ASM. Aluminum is often noted for having a high strength compared to plain steel at low temperatures.

When making a comparison to aerospace stainless steel, it’s important to specify the exact steel alloy. This is because there are many different formulations of stainless steel—each one with its own unique characteristics.

For example, grade 304 stainless steel has a higher ultimate tensile strength than aluminum—505 MPa (73,200 psi)—but weighs 8 g/cm3, nearly triple the weight of aluminum. 304 stainless steel for aerospace applications is highly resistant to corrosion thanks to its protective oxide layer, which inhibits oxidation.

Here’s a quick comparison table:

Mechanical Property

Aluminum

304 Stainless Steel

316 Stainless Steel

Ultimate Tensile Strength

310 MPa (45,000 psi)

505 MPa (73,200 psi)

580 MPa (84,100 psi)

Weight

2.7 g/cm3

8 g/cm3

8 g/cm3

Shear Modulus

26 GPa (3770 ksi)

86 GPa (12,500 ksi)

82 GPa (11,893 ksi)

Melting Point

582-652˚C (1,080-1,205˚F)

1,400-1,455˚C (2,550-2,650˚F)

1,370-1,400˚C (2,500-2,550˚F)

In short, while stainless steel alloys are heavier than aluminum, they also have a higher tensile strength, shear modulus, and melting point than aluminum does.

What is Aerospace Steel Most Useful for?

While building an entire aircraft from stainless steel would be impractical because of how much heavier it is than materials like aluminum, there are some specific applications where aerospace grade stainless steel may surpass aluminum. Some examples include:

  • Engine and Exhaust Components. The corrosion resistance and higher temperature tolerance of stainless steel aerospace components can lead to better useful life and performance.

  • Landing Gear Components. The high tensile strength and shear modulus of stainless steel makes it far more suitable for absorbing the impact stresses that landing gear must endure.

  • Key Superstructure Joints. Aerospace stainless steel can be used in key joints in an aircraft’s superstructure to improve durability and reduce risk of failure during flight.

Aside from using stainless steel in aircraft parts, many aerospace manufacturers use stainless steel baskets to process their parts. These baskets can handle heavy loads while facilitating better parts cleaning and finishing—helping aerospace companies save time and money on their manufacturing processes.

Learn more about how to use stainless steel components in your aircraft by reaching out to the Marlin Steel team today.

Contact Marlin Steel

Author: Marlin Steel
Marlin Steel
Marlin Steel is a leading manufacturer of custom‐engineered products from steel wire and sheet metal. Its industrial material handling containers serve many industries including aerospace, defense, medical and automotive.

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