Hastelloy B2 vs C22 – What’s the Difference
Hastelloy is a family of nickel-based alloys highly resistant to corrosion, oxidation, and high-temperature applications. In this blog post, we will compare two of the most popular members of the Hastelloy family: B2 and C22. These two alloys are widely used in the chemical processing industry, where their corrosion resistance and durability are essential. We will explore the differences between Hastelloy B2 and C22 and help you decide which alloy suits your requirements.
Difference Between Hastelloy B2 and C22
Chemical Composition
Hastelloy B2 and C22 have different chemical compositions, which affect their performance in specific environments. Hastelloy B2 contains 26% molybdenum, 1% iron, and 68% nickel, while Hastelloy C22 has a higher concentration of molybdenum (22%), chromium (22.5%), and a smaller amount of iron (3%). The higher chromium content in C22 enhances its resistance to oxidizing agents such as nitric acid, chlorine, and sulfuric acid, whereas B2 is better against reducing media, such as hydrogen chloride gas and acetic acid. So, the choice of alloy will depend on the chemical composition of the environment where it will be used.
Temperature Resistance
Both alloys resist high temperatures, but their respective temperature ranges differ slightly. Hastelloy C22 can handle temperatures up to 1250°C, while B2 can withstand temperatures up to 1095°C. This means that C22 can handle more extreme temperatures than B2, which makes it more suitable for applications that require high-temperature resistance.
Fabrication and Welding
Hastelloy B2 is easier to fabricate and weld compared to C22. B2 has a lower carbon content that reduces the risk of sensitization. Sensitization is a condition where the precipitation of carbides can occur on the boundary of the grains, making the alloy vulnerable to corrosion. C22, on the other hand, requires more skill and experience during fabrication and welding due to its higher carbon content. Its higher chromium content makes it more vulnerable to sensitization.
Cost
Hastelloy C22 is more expensive than B2 due to its higher concentration of molybdenum and chromium. If cost is a significant factor, B2 is the more affordable option. However, the overall cost will depend on the specific requirements of your application.
Application
Hastelloy B2 and C22 are both suitable for numerous applications. B2 is commonly used in reactors, heat exchangers, and furnaces that require high resistance to reducing media. C22 is used in the chemical processing industry, particularly in corrosive environments that require high resistance to oxidizing agents. Both alloys can withstand highly corrosive environments and provide long service life when used correctly.
Conclusion
Choosing the right Hastelloy alloy for your specific application depends on several factors, such as chemical composition, temperature resistance, fabrication and welding processes, and cost. Hastelloy B2 is more affordable and has excellent resistance to reducing media, while Hastelloy C22 is more expensive but can handle more extreme temperatures and has high resistance to oxidizing agents. Both alloys provide long service life when used correctly. Hence, a thorough understanding of your requirements is essential to make an informed decision.
