Benefits of Stellite™ Cobalt Castings
Considered a universal alloy, Stellite™ is relied upon by manufacturers for its excellent mechanical properties and superior wear, oxidation, corrosion, impact, and shock resistance at elevated temperatures. Stellite™ alloys are also commonly used in the investment casting process.
Despite the many advantages of Stellite,™ there are several factors to consider before deciding to use it for your investment casting project. It is important to understand the chemical composition, mechanical properties, and how that material will react during the manufacturing process.
In this brief guide, we’ll cover the basic chemical composition of Stellite,™ compare it to other alloys on the market, and help you understand how, when, and why to use it for your casting application.
Stellite™ refers to a group of cobalt-chromium alloys that contain some combination of carbon, tungsten, molybdenum, nickel, iron, manganese, and silicone. They generally have excellent wear, cavitation, abrasion, and corrosion resistance. Stellite™ 3, 6, 21, and 31 are just some of the alloys that comprise the Stellite™ family.
Stellite™ 3 alloys are composed of cobalt, chromium, tungsten, nickel, iron, manganese, and silicon. Stellite™ 6 contains lower amounts of cobalt, chromium, and tungsten compared to Stellite™ 3, but also contains molybdenum, nickel, iron, silicon, and manganese. Stellite™ 21 contains carbon, chromium, molybdenum, and cobalt, while Stellite™ 31 contains higher amounts of carbon and lower amounts of chromium, tungsten, cobalt, and nickel.
While the chemical makeup of the many Stellite™ alloys varies from one to the next, the carbon and chromium content can be considered the elements that impact the alloys’ performance the most. High-carbon Stellite™ alloys have excellent wear resistance, while low-carbon alloys perform well in high-temperature applications. Finally, low-carbon and high-chromium alloys have excellent corrosion resistance.
Benefits of Stellite™
The primary benefit of Stellite™ alloys is their ability to maintain their superior mechanical properties, such as strength and high hardness, at elevated temperatures. As previously mentioned, these alloys are relied upon for their excellent wear, impact, corrosion, and erosion resistance. However, the same properties that make Stellite™ alloys so valued are the same properties that decrease its machinability. Although the hardness value of Stellite™ makes it difficult to machine, it’s still one of the best alloys to use for investment casting. When using Stellite™ for investment casting, manufacturers are able to produce parts with tight tolerances, reducing the need for machining.
Advantages of Using Stellite™ Over Stainless Steel
While Stellite™ alloys are more expensive than other metal alloys like stainless steel, they don’t require as many additional processing steps after casting. The cobalt matrix and complex microstructure within Stellite™ alloys provide them with much better corrosion, wear, oxidation, and heat resistance than stainless steel or other metal alloys.
Lastly, Stellite™ alloys perform much better than stainless steel at high temperatures. Therefore, Stellite™ is not only a stronger and more durable material, but it also has superior corrosion, oxidation, and wear resistance than stainless steel at much higher temperatures.
Most Commonly Used Stellite™ Alloy
The most common Stellite™ alloy used to produce castings is Stellite™ 6. These cobalt-chromium and tungsten Stellite™ alloys have a Rockwell Hardness Value of 42 HRC and an operating temperature approaching 1,100 degrees Fahrenheit.
Like all Stellite™ alloys, Stellite™ 6 has fantastic wear and oxidation resistance, as well as a low coefficient of friction. Stellite™ 6 castings also have excellent impact and shock resistance and don’t typically require additional heat treatments.
Stellite™ 6 castings are most commonly used in the Aerospace and Oil/Gas industries. Petrochemical and refining processes use air, chamber, reactor, and stripping nozzles cast from Stellite™ 6. Pumps, pump components, and valves are also cast from Stellite ™ 6.
Find Your Solution With Help From Barron Industries
Barron Industries is an ISO 9001 and AS 9100-accredited investment casting foundry. We have the ability to produce castings from over 200 ferrous and non-ferrous alloys, including Stellite™ 3, 6, 21, and 31. To ensure quality, our state-of-the-art facility also includes a NADCAP-certified non-destructive testing lab for digital radiography and liquid penetrant testing. If you have general questions about Stellite™ or want to learn more about our turnkey capabilities, please contact us today.