Hastelloy C22 (UNS N06022): A Super Alloy Offering Superior Performance in Abrasive Environments
Hastelloy C22 is a nickel-based super alloy developed with the aim of showing extraordinary resistance to abrasive chemical environments. The basic composition of the alloy contains approximately 56% nickel, 20-23% chromium, 12.5-14.5% molybdenum, 2.5-3.5% iron, 2-6% tungsten, and small amounts of cobalt, vanadium, copper, carbon and silicon.
Hastelloy C22 has been designed particularly for use in chemical systems that alternate between oxidising and reducing environments. Thanks to the multiple protective element content of the material, it provides high durability against both the pitting corrosion caused by chloride ions and stress corrosion cracking.
Its microstructure is austenitic, and it can reach the desired strength and forming properties with a combination of solution annealing and cold working. It has high ductility at room temperature; at the same time its mechanical strength is largely preserved at temperatures between 400–600 °C.
Hastelloy C22 Relevant Standards
The production, quality control and supply of the Hastelloy C22 alloy are carried out according to the following ASTM, ASME and AMS norms:
- ASTM B575 – Sheet, plate and strip products
- ASTM B564 – Forged and flange parts
- ASTM B619 / B622 / B626 – Pipe and tube products
- ASTM B366 – Welded fittings
- ASME SB-575 / SB-619 – Usability in pressure vessels
- UNS N06022 – Unified Numbering System designation
- Werkstoff Nr. 2.4602 – German standard number
Compliance with these standards is mandatory in terms of certified material supply in critical fields such as the chemical, energy, pharmaceutical and defence industries.
Hastelloy C22 Trade Names and Equivalents
- Hastelloy® C-22® – Trade name registered by Haynes International
- Alloy C-22 – The name widely used in technical documents and commercial catalogues
- UNS N06022 – Chemical composition identifier
- W.Nr. 2.4602 – European designation number
- NiCr21Mo14W – Its equivalent in the EN standard
Among some equivalents of Hastelloy C22 are alloys such as INCONEL 686, Alloy 59, Nicrofer 5621 and Haynes 22. C22, however, stands out in this group with the broadest spectrum of corrosion resistance.
Application Areas
Hastelloy C-22 has been developed specifically for systems operating in very aggressive chemical environments and is widely used in the following fields:
1.Chemical and Petrochemical Plants
*Sulphuric, nitric, hydrochloric and phosphoric acid production and transport systems
*Chlorine-containing process tanks and in-reactor coils
*Acid recovery and separation systems
2.Pharmaceutical and Biotechnology Industry
*Reactor linings and agitator assemblies
*Pipelines resistant to cleaning chemicals
*Systems durable against bacterial and microbial contamination
3.Waste Water and Acidic Fluid Treatment Systems
*Pipes and tanks in which abrasive liquids are carried
*Internal surface plates used in gas scrubber systems
4.Nuclear and Power Plants
*Coolant pipes in contact with radioactive media
*Gaskets and fittings operating at high pressure and temperature
5.Surface Treatment and Metal Plating Systems
*Electroplating tanks
*Abrasive electrolyte transfer lines
In these application areas the reason why Hastelloy C22 is preferred is that it can show two-way resistance to both oxidising and reducing substances.
Advantages
- Superior Corrosion Resistance: C-22 provides comprehensive protection against both oxidising (nitric acid, hypochlorite) and reducing (hydrochloric, sulphuric) environments.
- Pitting and Stress Corrosion Resistance: It is resistant to subsurface pit formation and stress cracking in environments containing chloride.
- High Temperature Strength: It preserves its mechanical and chemical stability at temperatures up to 600 °C.
- Weldability: Successful joining can be achieved with common welding methods such as GTAW and GMAW. The grain structure is not disturbed after welding.
- Metallurgical Stability: Grain boundary precipitation is at a minimum level, so the internal structure remains stable in long-term use.
Disadvantages
- High Cost: Because of the high proportion metals it contains, such as nickel, molybdenum and tungsten, its cost is high compared with carbon steel and some stainless steels.
- Machining Difficulty: Cutting tool life may decrease with cold worked material, and special cutting fluids and a low feed rate are required.
- Limited in Extremely High Pressure Systems: In situations requiring very high mechanical strength it may remain limited when compared with alloys such as 718 or C-276.
Conclusion and Industrial Evaluation
Hastelloy C22 is an alloy offering extraordinary resistance in a very wide variety of chemical environments and providing safety and sustainability on an industrial scale with its high nickel, molybdenum and chromium content. Especially in complex processes where both oxidising and reducing environments are present together, offering a broad solution field on its own is the principal property that sets it apart from other super alloys.
Although its high cost means it should be used only in critical systems, it should be assessed as one of the main components of a long-term investment in plants carrying a heavy chemical corrosion risk. Hastelloy C22 lies at the centre of technical engineering solutions and is an alloy used with confidence in complex processes.
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| Chemical Composition (NiCr21Mo14W) | | Mechanical Properties at Room Temperature | |
|---|---|---|---|
| Grade | Hastelloy C-22 (2.4602) | Properties | Values |
| Ni | 50-63% (typically ~59%) | Density (Specific Gravity) | 9220 kg/m³ |
| Cr | 20.0-22.5% | Melting Point | 1370 – 1420 °C |
| Fe | 2.0-6.0% | | |
| Mo | 12.5-14.5% | | |
| W Tungsten | 2.5-3.5% | | |
| Co | max 2.5% | | |
| C | max 0.015% | | |
| Mn | max 0.5% | | |
| Si | max 0.08% | | |
| P | max 0.02% | | |
| S | max 0.02% | | |
| V | max 0.35% | |
We supply this material
We supply Hastelloy C22 (2.4602) — to ASTM B574 / ASTM B575 standards, in the dimensions and forms required. For stock availability and pricing:
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