Fasteners, no matter how small, play an important role in many industries, including chemical, petrochemical, and oil and gas. They need to be strong enough to withstand harsh environments and prevent leaks or corrosion. Hastelloy C276 and Hastelloy C22 Fasteners are two popular choices. But what are the differences between these two alloys? In this blog post, we will take a closer look at Hastelloy C22 vs C276 Fasteners and help you make an informed decision for your next project.
What Are Hastelloy C22 Fasteners?
Hastelloy C22 Fasteners are highly corrosion-resistant fastening components made from an alloy of chromium, molybdenum, and tungsten. They provide superior protection against a wide range of corrosive materials, including acids and alkalis found in industrial settings. The alloy is also extremely resistant to high temperatures which makes it ideal for use in systems handling hot fluids or vapors. It provides excellent weldability along with good formability and machinability making it the perfect material for attaching parts securely and reliably for many applications.
Composition
Hastelloy C22 and C276 are both nickel-chromium-molybdenum alloys, with tungsten and cobalt additions. However, they differ in composition. Hastelloy C22 has a lower carbon content (0.010% max) and higher chromium (22%) and molybdenum (13%) than C276. It also has a small amount of tungsten (3%). On the other hand, C276 has a higher carbon content (0.010% max) and slightly lower chromium (16-18%) and molybdenum (12.5-14.5%), with a higher tungsten content (4-5%). The differences in composition affect the alloys’ mechanical and chemical properties, such as corrosion resistance, high-temperature strength, and weldability.
Corrosion Resistance
Both alloys are known for their exceptional corrosion resistance in highly aggressive environments, such as wet chlorine gas, sulfuric and hydrochloric acid, and seawater. However, Hastelloy C22 has better resistance to localized corrosion, such as pitting and crevice corrosion, due to its higher chromium and molybdenum contents. This makes it a popular choice for components like valves, pumps, and manifolds in the chemical processing and pharmaceutical industries. On the other hand, C276 has a better overall corrosion resistance, especially in reducing and oxidizing environments, at higher temperatures. This makes it suitable for applications in the oil and gas industry, where well fluids and gases can be highly corrosive.
Mechanical Properties
Hastelloy C22 and C276 both exhibit excellent mechanical properties, including high strength, ductility, and toughness, at both room and elevated temperatures. However, there are some differences. Hastelloy C22 has a lower work-hardening rate, making it easier to form and machine into complex shapes. At the same time, it has a lower yield strength and ultimate tensile strength than C276, but better impact strength. C276, on the other hand, has a higher yield and tensile strength than C22, but its hardness increases rapidly when exposed to high temperatures. This makes it more suitable for high-pressure and high-temperature applications, such as heat exchangers and reactors.
Cost
The cost of Hastelloy C22 vs C276 is another factor to consider when choosing the right alloy for your fasteners. Generally, C276 is more expensive than C22, due to its higher tungsten content and good overall properties. However, the exact cost will depend on the form, size, and quantity of fasteners you need, as well as the supplier you choose. It is always important to compare prices and quality from different suppliers before making a purchase.
Conclusion
Hastelloy C22 and C276 are both excellent choices for fasteners in corrosive and high-temperature environments. While they share some similarities, they also have some distinct differences in composition, corrosion resistance, mechanical properties, and cost. Choosing the right alloy for your specific application requires careful consideration of all these factors, as well as other factors like design requirements, operating conditions, and maintenance needs. By understanding the differences between Hastelloy C22 vs C276 fasteners, you can make an informed decision and ensure the quality and safety of your project.
