Aircraft are some of the most advanced and meticulously designed machines in modern engineering. Nothing, from the individual bearings to the large superstructures, is left up to chance when it comes to design and composition. One of the most critical elements in aircraft engineering has always been the material that various components are made from, which has changed many times over the years as material technology has advanced. Known for its reliability and cost-effectiveness, one type of material that has stuck around since the earliest days of aviation is stainless steel. In this blog, we will discuss this longstanding material and describe why it has played such a large part in aviation history.
The framework for choosing materials in aviation consists of several equally important factors, including weight, corrosion resistance, economic feasibility, and durability. It is by these metrics that engineers and airlines evaluate the different options and make their decision. Before discussing how stainless steel stacks up against these considerations, it is first beneficial to understand the history of this material in aviation. Stainless steel was first reproduced in large quantities by Harry Brearley. While looking for a metal combination that would provide the military with a rust-avoiding material, he found that a discarded experimental alloy did not form any rust. This alloy was very similar in composition to the stainless steel that would go on to predominate the market.
Stainless steel is not homogenous in its composition. In fact, there are several types of stainless steel that may be chosen to precisely fit an application of interest. Austenitic stainless steel accounts for the vast majority in use, made from a combination of steel and nickel, manganese, and nitrogen. This class provides excellent performance in a vast array of operating temperatures. Ferric stainless steel incorporates a greater amount of chromium while also containing magnetic additives, such as titanium and zirconium. While not as durable as other options, ferric stainless steel is incredibly corrosion-resistant. Finally, martensitic stainless steel is a carbon-containing alloy that can be heat-treated to increase physical resilience.
While aluminum and aluminum alloys predominate the modern aviation industry due to their cost and lightweight nature, stainless steel still remains a viable and widely used option for high-performance components. For example, engine and fuel parts that are commonly exposed to fluctuating temperature and constantly inundated with corrosive materials are nearly uniformly composed of stainless steel derivatives. Likewise, stainless steel is chosen regularly to cast the fasteners that hold aircraft together.
When directly compared to aluminum, stainless steel features much higher tensile strength, regardless of the subtype being used. Additionally, the shear modulus of stainless steel, on average, is 8,000 ksi higher than aluminum. The difference between the melting point is even more drastic, with stainless steel featuring operating temperatures up to 1,400 degrees C, compared to the 650 degrees C exhibited by aluminum. However, aluminum is considerably less dense than stainless steel, with a difference of 5-6 g/cubic centimeters depending on the particular material. When constructing a large aircraft, this discrepancy becomes enormous and may translate to millions of dollars in cost differences.
Whether your application calls for stainless steel or aluminum components, you cannot go wrong when you choose Aviation Distribution to help source them. As a leading distributor, we give customers direct access to an inventory of over 2 billion ready-to-purchase items for the civil and defense aviation industries. With an unparalleled number of parts to choose from, we can help you find all the new, obsolete, and hard-to-find products you need. Additionally, we are the only independent distributor with a strict NO CHINA Sourcing policy to ensure full traceability with each order, as applicable.
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