Hastelloy C22 and Hastelloy C276 are two readily available alloys when choosing a corrosion-resistant alloy. They both belong to the Hastelloy nickel-based family and are known for their excellent properties in resisting various forms of corrosion. But how do they differ from each other? In this blog post, we will explore the differences between Hastelloy C22 and C276 and guide you in making an informed decision in choosing which one to use for your industrial needs.
What is Hastelloy C22?
Hastelloy C22 is a nickel-chromium-molybdenum superalloy with excellent resistance to oxidizing and non-oxidizing acids, pitting, and crevice corrosion. It is used in chemical processing applications for its unmatched strength and resistance to localized corrosion. It can also handle higher temperatures than other alloys, making it ideal for high-temperature environments.
What is Hastelloy C276?
Hastelloy C276 is a nickel-molybdenum-chromium-tungsten alloy with superior corrosion resistance in harsh, aggressive environments. It is often used in marine, chemical processing and pollution control applications due to its outstanding strength, thermal stability and formability.
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Difference Between Hastelloy C22 and C276
Chemical Composition
Chemical composition is a critical factor to consider when deciding which alloy to use. Hastelloy C22 contains a lower percentage of molybdenum and tungsten than C276. The presence of chromium, molybdenum, and tungsten in C276 gives it better overall corrosion resistance than C22, which has great resistance to localized corrosion attack but falls short when exposed to highly oxidized situations.
Temperature Range
Hastelloy C22 excels in environments with high temperatures that fall within a range of 2,000°F. It’s superior due to its capability of handling numerous acids, such as sulfuric, hydrochloric, and hydrofluoric, known to increase in levels with rising temperatures. On the other hand, Hastelloy C276 has a relatively broader temperature range and can work in temperatures up to 2,300°F.
Weldability
Hastelloy C22 and C276 have moderate to good weldability compared to other alloys in this family. However, Hastelloy C276 is more difficult to weld than C22 due to its need for controlled heating and cooling, which is more complex than C22’s welding operation. Overall, both alloys are amenable to routine welding practices.
Applications
Hastelloy C276 is widely used in organic chloride and chemical processing units that encounter various chemical elements such as corrosive gases, acids and seawater. While C22 is more commonly used in cupric and nickel-chromium alloys as it shows extraordinary resistance to various forms of pitting.
Cost
Regarding the cost of alloying, it takes work to determine which is superior since other factors like location and quantity would play a significant role. However, overall, Hastelloy C276 is considered slightly more expensive due to the need for stronger heat treatments during welding.
Conclusion
Hastelloy C22 and Hastelloy C276 are excellent corrosion-resistant alloys, each with unique benefits. If you’re looking for an alloy that offers optimal protection against localized corrosion, Hastelloy C22 is an excellent choice. If you need a corrosion-resistant alloy that can withstand high temperatures, go for Hastelloy C276. Regardless of which one you choose, make sure that you select an alloy that will provide excellent resistance to the specific environment you plan to use it.
