Alloy C22 / UNS N06022 / W.Nr. 2.4602
Hastelloy C22
Alloy C-22, also known as HASTELLOY® C-22, is a versatile nickel-based superalloy that offers superior resistance to corrosion in a range of harsh environments. With its high chromium, molybdenum, and tungsten content, this alloy provides excellent protection against both oxidizing and reducing media.
The fully austenitic structure of Alloy C-22 makes it immune to sensitization, ensuring it retains its corrosion resistance even after exposure to high temperatures. This makes it an ideal choice for applications that demand long-term reliability and performance. In comparison to other alloys, such as C-276, C4, and 625, Alloy C-22 offers improved overall corrosion resistance and durability.
Industries and Applications
With its resistance to a broad range of corrosive environments, Alloy C-22 is ideal for use in many applications, including waste incinerators, flue-gas desulfurization scrubbers, nuclear fuel reprocessing and spent fuel containers, pickling systems, heat exchanger components, chemical manufacturing equipment, flow meters and many others. The maximum service temperature for Alloy C-22 is 1250 °F.
Resistance to Corrosion
Alloy C-22 demonstrates outstanding resistance to oxidizing aqueous media, such as wet chlorine and mixtures containing nitric acid or oxidizing acids with chlorine ions. Additionally, it offers excellent resistance to reducing acids, such as sulfuric and hydrochloric acid, as well as a variety of corrosive chemicals, including oxidizing acid chlorides, formic and acetic acids, ferric and cupric chlorides, sea water, brine, and mixed or contaminated chemical solutions, both organic and inorganic. With its resistance to both reducing and oxidizing conditions, Alloy C-22 is ideal for use in multi-purpose plants where “upset” conditions frequently occur.
Fabrication and Heat Treatment
Alloy C-22 can be formed using standard processes for nickel alloys, though intermediate annealing may be required due to work hardening. Forging should be performed between 1750°F and 2050°F, followed by rapid cooling, while annealing should be done at a temperature range between 2020°F and 2150°F, with a rapid quench. Welding can be done using gas tungsten-arc, gas metal-arc, and shielded metal-arc processes. The alloy’s heat treatment must be performed at an accelerated rate to avoid the formation of detrimental phases which form between 400°F and 1800°F.
Hastelloy C22 – Applicable Specifications
| Form | ASTM | ASME | Other |
|---|---|---|---|
Alloy C22 Plate & Sheet |
B575 | SB-575 | – |
Alloy C22 Bar |
B574 | SB-574 | AMS 5751, AMS 5747 |
Alloy C22 Pipe |
B622 | SB-622 | – |
Alloy C22 Fittings |
B366 | SB-366 | – |
Alloy C22 Welding Wire |
B574 | SB-574 | – |
Alloy C22 Forgings |
B564 | SB-564 | AMS 5751, AMS 5747 |
Common Trade Names
INCONEL® alloy 22 and HASTELLOY® C-22® are trademarks of well-known corporations. INCONEL® is a trademark owned by Special Metals Corporation, while HASTELLOY® is a registered trademark of Haynes International Inc.
Key Properties
(in annealed condition)
| Tensile strength: | 880 MPa |
| Yield strength: | 730 MPa |
| Elongation: | 40% |
| Hardness: |
Rockwell C35 |
Chemical Composition (%)
| Element | Composition |
|---|---|
| Nickel | Balance |
| Chromium | 22% |
| Molybdenum | 13% |
| Tungsten | 2.5% |
| Cobalt | 1.5% |
| Iron | 1.0% |
| Manganese | 1.0% |
| Silicon | 0.08% |
| Carbon | 0.03% |
| Sulfur | 0.01% |
| Phosphorus | 0.01% |
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