In the aerospace industry, the demands placed on materials are incredibly high as components must withstand extreme temperatures, mechanical wear, and corrosive environments while maintaining structural integrity. Over the years, certain alloys have proven to be exceptional in meeting these rigorous standards. Among them, the Kennametal Stellite™ family of alloys stands out as a key player in ensuring the longevity and performance of aerospace components. Stellite™ alloys have played a historic role in aerospace, with some of these materials dating back to the early 1900s. Today, they continue to push the boundaries of aerospace.
Explore the Kennametal Stellite™ Legacy in Aerospace Alloys
Stelllite turbine blades for jet engines are measured in the 1960s
The Legacy of Stellite Alloys
Stellite alloys, primarily made from cobalt, chromium, and other elements, have been used for decades in some of the most critical applications in aerospace, including the combustion zone, hot gas paths, bearings, and valves. These alloys were developed with a focus on providing exceptional resistance to high temperatures, corrosion, and mechanical wear—critical qualities for materials used in engines and other high-stress components.
Some of the most longstanding and proven Stellite alloys include Stellite 6 and 6B, Stellite 31, Stellite 21, Nistelle X, and more. Let’s take flight and explore the distinct properties of these alloys and what makes them key contributors in aerospace.
Proven Properties and Applications of Legacy Alloys in Today’s Solutions
- Stellite 6 and 6B (AMS 5387 / AMS 5894)
First issued in 1913, Stellite 6 and its variant, Stellite 6B, are two of the most widely used alloys in aerospace. The alloys were covered under the Haynes patent, developed by Elwood Haynes and later named Stellite. Known for their outstanding resistance to mechanical and chemical wear, these alloys are ideal for applications exposed to abrasive conditions. - Stellite 31 (AMS 5382)
Introduced in 1941 Stellite 31, or X-40, has been used to invest in cast turbine buckets (or blades) in the world of aerospace. The alloy offers excellent corrosion resistance and high-temperature strength that excels in environments that demand both high mechanical performance and resistance to thermal shock. Stellite 31 is particularly suited for components exposed to extreme temperature fluctuations, such as its original use in turbine buckets and high-stress areas in jet engines. - Stellite 21 (AMS 5385)
Stellite 21 was first introduced to the aerospace sector in 1936 to address exhaust valve seat wear issues in radial engines. In addition, millions of buckets for aircraft superchargers were produced using investment casting of Stellite 21 alloy during and after World War II. Building on its impressive history, Stellite 21 was also among the first heat-resistant alloys tested for use in jet engines in 1947, solidifying its place as a key material in aerospace. Known for its exceptional high-temperature performance, Stellite 21 is particularly well-suited for components exposed to extreme heat, such as nozzles, turbine blades and other critical parts in the hot gas path of engines. - Stellite 3
Stellite 3 is notable for its high carbon content, which boosts its resistance to abrasion and solid particle erosion. This alloy is well-regarded for its metal-to-metal wear resistance, making it a top choice for components subjected to frequent contact and friction, such as seals and valve seats. - Stellite 25
With a low carbon content, Stellite 25 is prized for its excellent thermal fatigue, oxidation, and sulfidation resistance. Patented in 1954, this alloy is highly suitable for a variety of component applications in the aerospace industry, including parts in established military and commercial gas turbine engines. Additionally, it is widely used as a bearing material, for both balls and races, due to its durability and resistance to wear. - Stellite 694
A high-performance cobalt-chromium alloy with high tungsten content, Stellite 694 is engineered for use in extreme environments, where temperatures can reach up to 1148°C (2100°F). This alloy exhibits excellent resistance to wear, erosion, oxidation, and creep, making it ideal for components exposed to prolonged heat and mechanical stresses, such as turbine blades and nozzles. - Nistelle X (AMS 5390)
Nistelle X, also known as Hasteloy X, is a highly corrosion-resistant, nickel-base alloy that has demonstrated its exceptional performance since its patenting in 1955. Renowned for its strength and outstanding resistance to corrosion, it remains the preferred choice for critical components in the combustion zone of jet engines operating under extreme conditions.
Stellite is a Proven Choice for Aerospace Customers
The aerospace industry requires materials that deliver both reliability and performance. Stellite alloys provide numerous benefits to customers, including:
- Extended Component Life: Stellite alloys are engineered to resist wear, corrosion, and thermal degradation, meaning they help increase the lifespan of aerospace components, reducing the need for costly repairs or replacements.
- Enhanced Performance: These alloys are optimized for high-temperature applications, providing consistent performance in extreme environments. This makes them particularly useful for critical parts in engines, hot gas paths and bearings.
- Versatility and Availability: Stellite alloys are available in a variety of forms, including investment castings, bar-stock, sheet, and plate, allowing for tailored applications across a wide range of aerospace components. Additionally, Stellite products are available as weld consumables, including powder, wire and rod.
- Engineering Support: Kennametal Stellite offers unparalleled metallurgical and engineering expertise to assist customers in selecting the right material for their specific needs. From alloy selection to process optimization, the support provided ensures that customers receive the highest-quality solutions.
A Historic Legacy in Aerospace
From the pioneering of Stellite 21 to the versatile and widely used Stellite 6B, Kennametal’s Stellite alloys represent decades of innovation and excellence in materials science. Their ability to withstand the harshest conditions in aerospace—whether it's extreme temperatures, mechanical wear or corrosion—makes them indispensable in the industry. As we look toward the future, these legacy alloys continue to be integral to the aerospace sector, offering performance, durability and support to customers worldwide.