Hastelloy C22: A Nickel-Based Alloy That is Corrosion Resistant and High-Temperature Stable
Definition and Composition of Hastelloy C22
Hastelloy C22, also known as Alloy C22, is a nickel-based alloy composed of nickel, chromium, molybdenum, and tungsten. It outperforms other alloys made of nickel, chromium, and molybdenum, such as C276, C4, and 625 alloys, in terms of corrosion resistance. The high chromium content of Hastelloy C22 provides good oxidation resistance, while the addition of molybdenum and tungsten gives it good resistance to reducing media. This corrosion resistance makes C22 very useful in applications that deal with harsh environments such as strong acids.
Chemical Composition of Hastelloy C22
Hastelloy C22 is a nickel-chromium-molybdenum alloy that contains 56% nickel, 22% chromium, and 13% molybdenum, and also contains iron, tungsten, and cobalt. This alloy is commonly referred to as Hastelloy C22 and is also designated as UNS N06022. C22 has good corrosion and oxidation resistance, good mechanical properties over a wide temperature range, and also has good processing properties.
Characteristics of Hastelloy C22
1. Corrosion resistance
Hastelloy C22 is one of the most corrosion-resistant alloys on the market, and is even considered superior to C276 and C625. This nickel-based alloy is resistant to almost all reducing and oxidizing environments, including strong oxidants, seawater, and a variety of organic acids. In addition, it also has good resistance to localized corrosion caused by chlorides.
2. Oxidation resistance
C22 has good resistance to oxidation, carburization, and sulfidation at high temperatures, but it may form brittle phases when used at temperatures above 1250°F, so it is not ideal.
3. Mechanical properties
Hastelloy C22 is usually used in the annealed state and has a minimum yield strength. This alloy can be strengthened by cold working, and its melting point is 1399°C.
4. Heat treatment
Hastelloy C22 is usually annealed at 1121°C and then rapidly cooled, and its melting point is 2550°F.
5. Processing performance
Hastelloy C22 alloy can be cold worked and hot worked. C22 hardens rapidly during processing, and cold working must be carried out in stages with annealing in between. After cold working, the parts should be annealed.
Application of Hastelloy C22
Due to its excellent corrosion resistance, C22 is widely used in various harsh environment markets, including chemical processing, pharmaceuticals, power generation, food processing, oil and gas, and even papermaking industries. Here are some specific applications of Hastelloy C22:
Chemical processing
Oil and gas
Food processing
Power generation
Pharmaceutical industry
Pulp and paper industry
Nuclear fuel regeneration
Pesticide manufacturing
Pickling system
Sulfur dioxide cooling tower
Processing and heat treatment
Due to its good density, C22 is easy to hot forge, hot roll and hot stamp, and can be heat treated afterwards. C22 has a narrow hot working temperature range, with the recommended hot forging start temperature of 1232°C and the recommended hot working end temperature of 954°C.
