Hastelloy C22 vs C4 – What’s the Difference

Stainless steel is the most common alloy used to manufacture various industrial components. However, it has some limitations when operating in extreme environmental conditions. Hence, the need for high-performance alloys is increasing in today’s science and engineering world. The hastelloy family of alloys has emerged as the most used high-performance alloys due to their excellent resistance to corrosion, oxidation, and high temperature. Amongst the various hastelloy alloys available in the market, C22 and C4 are the most popular. This blog explains the differences between Hastelloy C22 and C4, their properties, and their applications.

Hastelloy C22 and C4 are both part of the hastelloy family of alloys. However, there are some notable differences between them regarding their compositions, properties, and applications. Hastelloy C22 comprises 22% of chromium, 12% of molybdenum, 2.5% of iron, and some minuscule amounts of tungsten, cobalt, and nickel. In contrast, C4 has a composition of 16% chromium, 16% molybdenum, 2.5% tungsten, and 1% iron. Unlike C22, C4 does not contain any nickel element.

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Hastelloy C22 and C4 differ in their properties, specifically their corrosion resistance. C22 has superior resistance to all forms of media, such as acidic, alkaline, and saline environments. It is highly resistant to pitting, crevice, and stress corrosion cracking. C4 offers excellent resistance to localized corrosion and stress corrosion cracking in hot chloride-containing media. C4 is an excellent alternative to C276 when no nickel contamination is allowed or required.

Hastelloy C22 is commonly used in chemical processing, pharmaceuticals, flue gas desulfurization systems, and pulp and paper industries. It is also popular in generating units requiring continuous operations and high temperatures and pressure. On the other hand, hastelloy C4 is commonly used in chemical processing, petrochemicals, and pharmaceuticals as an alternative to hastelloy C276. As mentioned, C4 is the best choice when nickel contamination is not allowed.

The mechanical properties of hastelloy C22 and C4 are relatively similar. Both alloys have comparable strength, ductility, and hardness. However, hastelloy C22 has a slightly higher endurance limit as compared to C4, which makes it the preferred choice in applications where dynamic loading is involved.


In summary, hastelloy alloys have become the most accepted high-performance alloys globally due to their excellent resistance to corrosion, oxidation, and high-temperature applications. Hastelloy C22 and C4 have unique compositions and properties that make them suitable for various industrial applications. C22 is highly resistant to corrosion and is typically used where continuous operations are required under extreme temperatures and pressure. C4, on the other hand, is an excellent alternative to C276 in situations where nickel contamination is not allowed or required. Before selecting the right hastelloy alloy for your application, it is essential to understand the difference between them to ensure that you choose the most appropriate alloy that meets your requirements.



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