Once an indispensable material of the aerospace industry, aluminum now makes up only about 20% of aircraft parts in a jet today. Other materials have since taken its place, with factors such as superior capabilities and the desire for lighter aircraft serving as reasons for replacement.
While composite materials and carbon-reinforced polymers are light and help reduce an aircraft’s weight, the need for corrosion resistant and hardy metal is strong. The result is a prominent increase in the use of stainless steel parts in the aerospace industry. Stainless steel parts are being used in aircraft and aerospace manufacturing now more than ever.
Uses of Aluminum vs Stainless Steel in Aerospace Manufacturing
Aerospace grade aluminum was once the preferred metal of the industry and it is still widely used. However, aluminum has been replaced by other materials with more strength and resistance to harsh environments.
Aluminum is a relatively lightweight material, weighing approximately 2.7 g/cm3 (grams per cubic centimeter). Though lighter and cheaper than stainless steel, aluminum is not as strong and corrosion resistant as stainless steel. When it comes to durability and strength, stainless steel outperforms aluminum.
In aerospace manufacturing, consistency and quality is essential. Stainless steel carts enable aviation parts cleaning and maintenance, repair, and overhaul (MRO) to run as efficiently as possible. Carts made from stainless steel can safely hold parts for assembly, reduce employee strain when manually moving parts, and can speed up drying after a parts washing process.
Properties of Aerospace Grade Aluminum
The popularity of aerospace grade aluminum can be traced to its attractive properties. Besides having high strength, aluminum is a lightweight material that can be easily machined and processed due to its high ductility. Aluminum can also be strengthened by adding additional metals such as copper, and through a cold or heat treatment.
In addition to being corrosion resistant, aluminum is also relatively cheap when compared to other metals due to being an atomic element.
Popular aerospace grade aluminum-based alloys include aluminum alloy 7075, 7475-02, and 6061 due to their light weight and high electrical conductivity.
Properties of Stainless Steel for Aviation
Stainless steel may seem a surprising choice over aluminum for aviation. After all, stainless steel is heavier than aluminum—and aircraft generally try to be as lightweight as possible. Still, stainless steel has several advantages over aerospace grade aluminum.
Stainless steel is highly resistant to corrosion, whether it's from atmospheric conditions or chemical solvents. Thanks to its protective oxide layer, stainless steel prohibits oxidation and corrosion. Additionally, stainless steel has greater strength than aluminum. Although aluminum is strong, stainless steel has a higher tensile strength and is able to resist impact damage better than aluminum can. For instance, grade 304 stainless steel has a higher ultimate tensile strength than aluminum—505 MPa (73,200 psi) vs 310 MPa (45,000 psi).
Besides a higher tensile strength, stainless steel has a greater shear modulus and a melting point than aluminum. These properties are essential for many aviation parts and enables stainless steel parts to be versatile options for aerospace applications.
Aluminum vs Stainless Steel: Properties.
Though aluminum is a lighter material, stainless steel has a higher tensile strength, melting point, and shear modulus than aluminum.
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)|
Stainless Steel Aerospace Applications
Stainless steel is now being used in a variety of applications, ranging from aerospace manufacturing to aviation parts. In aerospace manufacturing, stainless steel carts are used to create a more effective and efficient MRO process. Stainless steel custom wire baskets and carts enable a thorough parts cleaning and assembly without compromising parts protection.
In aerospace manufacturing, custom wire baskets can hold delicate, small parts through continuous chemical baths. Wire baskets with dividers and lids can protect parts from intermingling with each other and potentially escaping the basket during the cleaning process. Due to stainless steel’s excellent corrosion resistance, baskets made from stainless steel can also be subjected to continuous chemical processes without being corroded.
Stainless steel carts also can be an efficient means of quickly transporting delicate and large aviation parts through MRO processes. Carts can prevent metal-on-metal contact, keeping aircraft parts safe from damage and reducing rejection rates from surface scratches. The durability of stainless steel ensures that carts can withstand years of continuous use.
Aerospace applications where corrosion resistance, high melting point, and strength are necessary are ideal for stainless steel parts. Stainless steel is commonly used in airframes—the body of an aircraft—since the materials used here need to withstand extreme hot and cold temperatures as well as corrosives.
Landing gear and jet engines also benefit from being made in stainless steel. Both need to be exceptionally strong to withstand continuous flight. Additionally, the chromium in stainless steel resists deterioration and weathering. When the chromium encounters oxygen, it creates a protective oxide layer that enables stainless steel to endure extreme weather.
Marlin Steel's Stainless Steel Solutions
Marlin Steel prides itself on designing and delivering custom stainless steel products for the aerospace industry. Whether as an aviation cleaning basket or a custom cart, stainless steel is vital for efficient aerospace manufacturing and aircraft MRO.
Marlin Steel’s custom stainless steel carts are provided with neoprene liners (or other coatings) that prevent metal-on-metal contact—preventing parts from being damaged during movement. If you have a specific challenge for your aviation MRO, Marlin Steel’s engineers design wire and stainless steel solutions customized to your needs.
As a whole, stainless steel is essential for the 21st century aerospace industry.
Want to learn more about how to use stainless steel components in your aircraft? Do you need a custom aerospace parts cleaning basket? Start by reaching out to the Marlin Steel team today.