Views: 6 Author: Site Editor Publish Time: 2025-06-12 Origin: Site
Hastelloy alloy has become a key material in extreme environments such as chemical, energy and marine due to its excellent corrosion resistance. Hastelloy C22 and C276 are two different nickel-based high-temperature alloys, both of which are known for their excellent corrosion resistance and high-temperature performance, but there are some differences in chemical composition, physical properties and application areas. This article provides a comprehensive comparison of Hastelloy C22 and C276 to help understand the differences between them and determine their suitability in various industrial applications.
Shanghai Zhucheng Pipe Fittings Manufacturing Co Ltd. focus on the production of pipe fittings, flanges, bolts and other products using Hastelloy C22 and C276 materials, and are committed to providing customers with reliable and excellent corrosion-resistant alloy solutions. This article will compare Hastelloy C22 and C276 in detail to help you understand the differences between them and choose the right alloy according to the actual application.
Hastelloy C22
Hastelloy C276
Hastelloy C22 (N06022) Hastelloy alloy is a nickel-based high-temperature alloy composed of nickel, molybdenum, cobalt, tungsten and other elements, with a nickel content of about 60%. It is a versatile nickel-chromium-molybdenum-tungsten alloy with better overall corrosion resistance than other existing nickel-chromium-molybdenum alloys, including Hastelloy C-276, C4 alloy and 625 alloy. Hastelloy C22 alloy has good resistance to pitting, crevice corrosion and stress corrosion cracking. It has excellent resistance to oxidizing aqueous media, including wet chlorine, nitric acid or mixed acids of oxidizing acids containing chloride ions.
- Commonly used in high temperature and corrosive environments in chemical processing, petrochemical and power industries.
- Suitable for manufacturing equipment such as heat exchangers, reactors and valves.
- Also used for certain parts in aerospace and marine engineering.
Hastelloy C276 is a nickel-based alloy, belonging to the Hastelloy alloy series. It is mainly composed of nickel, chromium and molybdenum, and contains a small amount of iron, tungsten, cobalt and other elements. Compared with other nickel-based alloys, Hastelloy C276 has a strong ability to resist oxidation and reduction corrosion due to its unique chemical composition combination, especially in acidic and high temperature environments.
- Widely used in chemical, marine engineering, nuclear industry and aerospace fields.
- Particularly suitable for manufacturing equipment working in chloride environments, such as parts of offshore platforms and parts of chemical equipment.
- Also used in pollution control equipment such as scrubbers and flue gas desulfurization systems.
Both of these Hastelloy alloys are nickel-based and contain high proportions of chromium (Cr), molybdenum (Mo) and tungsten (W), which are key to their excellent corrosion resistance. Their low carbon (C) and silicon (Si) contents are intended to optimize weldability and reduce susceptibility to intergranular corrosion.
The most notable feature of C22 is its higher chromium content, which makes it perform better than C276 in oxidizing media. C276 has a higher molybdenum content, which contributes to its corrosion resistance in reducing media.
Element | Carbon (C) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) | Silicon (Si) | Chromium (Cr) | Nickel (Ni) | Molybdenum (Mo) | Cobalt (Co) | Iron (Fe) | Tungsten (W) | Vanadium (V) |
Hastelloy C22 | ≤0.015 | ≤0.50 | ≤0.02 | ≤0.02 | ≤0.08 | 20.0 – 22.5 | Remainder (rem) | 12.5 – 14.5 | ≤2.5 | 2.0 – 6.0 | 2.5 – 3.5 | ≤0.35 |
Hastelloy C276 | ≤0.01 | ≤1.00 | ≤0.04 | ≤0.03 | – | 14.5 – 16.5 | Remainder (rem) | 15.0 – 17.0 | ≤2.5 | 4.0 – 7.0 | 3.0 – 4.5 | ≤0.35 |
Mechanically, both Hastelloy C22 and C276 exhibit excellent strength and toughness, meeting the needs of most demanding industrial applications. C22 may have a slight advantage in yield strength, but overall, the difference in mechanical properties is usually not as significant as the difference in corrosion performance and is not the most important consideration when choosing between the two.
These mechanical properties make both alloys suitable for a wide range of applications, including chemical processing, oil and gas, power generation, and aerospace. The choice between the two usually depends on the specific requirements of the application, such as the need for higher corrosion resistance or better formability.
Hastelloy C22:
-Has high thermal stability and good mechanical properties.
-Maintains its strength and corrosion resistance at high temperatures.
-Suitable for parts working in high temperature and corrosive environments.
Hastelloy C276:
-Also has good high temperature strength and corrosion resistance.
-Due to its special alloy design, C276 performs particularly well in chloride environments.
-Also has good welding performance and hot and cold processing performance.
Common excellent corrosion resistance
1. Comprehensive corrosion resistance: Both can resist a wide range of highly corrosive media, including oxidizing and reducing environments.
2. Local corrosion resistance: Both have excellent resistance to pitting corrosion, crevice corrosion and stress corrosion cracking (SCC). This is crucial for media containing chloride ions, halides, etc. that are prone to local corrosion.
3. Welded corrosion resistance: Both have extremely low carbon (C) and silicon (Si) contents, which minimizes the precipitation of intergranular carbides in the weld heat affected zone (HAZ), so they can still maintain good corrosion resistance in the welded state (usually without post-weld solution heat treatment), especially intergranular corrosion resistance.
4. Resistance to various acids: They show good tolerance to sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, and organic acids such as formic acid and acetic acid.
Comparison of key differences in corrosion resistance
Corrosive Environment | C22 Performance | C276 Performance | Comparison Result |
Oxidizing acids (e.g. nitric acid, wet chlorine gas) | Excellent (high Cr content, superior oxidation resistance) | Good, but slightly inferior to C22 | ✅ C22 is stronger |
Reducing acids (e.g. hydrochloric acid, phosphoric acid) | Good, but slightly weaker than C276 | Excellent (high Mo and W content) | ✅ C276 is stronger |
Mixed acids (e.g. sulfuric acid + chlorides) | Outstanding general corrosion resistance | Excellent, but slightly lower than C22 | ⚖️ C22 slightly better |
Chloride-induced corrosion (pitting/crevice) | High PREN value (excellent chloride corrosion resistance) | Good, but slightly lower PREN | ✅ C22 is stronger |
Wet chlorine gas, sodium hypochlorite | Excellent resistance to oxidizing chlorine corrosion | May show slight corrosion | ✅ C22 clearly outperforms C276 |
Stress Corrosion Cracking (SCC) | High resistance | High resistance | ⚖️ Both are excellent |
Seawater / Salt spray | Excellent | Excellent | ⚖️ Comparable |
High-temperature corrosion (>500°C) | Stable and suitable | Stable, but slightly lower performance | ⚖️ C22 slightly better |
Hastelloy C22：
The C22 alloy exhibits good metallurgical stability at elevated temperatures, particularly under long-term service conditions up to 600°C. Its microstructure remains stable, offering strong resistance to intergranular corrosion. With a higher chromium content (approximately 22%), C22 provides superior high-temperature oxidation resistance, making it especially suitable for aggressive oxidizing atmospheres such as wet chlorine and hot nitric acid. C22 also maintains good strength below 600°C, though its mechanical strength decreases more rapidly beyond this temperature.
Hastelloy C276：
C276 alloy also maintains structural stability at high temperatures, but compared to C22, it is more prone to intermetallic phase precipitation during prolonged exposure, which can reduce its toughness and corrosion resistance. While C276 does possess some oxidation resistance, its lower chromium content (around 15%) makes it less effective than C22 in high-temperature oxidizing environments. However, C276 has slightly higher tensile strength than C22 and can retain good mechanical properties even at extreme temperatures (e.g., above 800°C).
Hastelloy C22: Generally more expensive due to its greater resistance to a wider range of corrosive environments and superior weldability.
Hastelloy C276: A cost-effective choice for applications requiring excellent corrosion resistance in challenging environments, making it a top choice for many industries.
However, the exact cost depends on the shape, size, and quantity of fasteners you require, as well as the supplier you choose. Always compare prices and quality from different suppliers before purchasing.
In summary, Hastelloy C22 and C276 are both highly versatile alloys, renowned for their corrosion resistance and mechanical strength in harsh environments. Hastelloy C22 offers outstanding resistance to a wide range of acids and chlorides, making it well-suited for applications requiring broad chemical resistance. If your application involves strong oxidizing agents, high-concentration wet chlorine, hypochlorites, chlorates, or demands exceptional resistance to localized corrosion (such as pitting and crevice corrosion), and the budget allows, Hastelloy C22 will deliver superior performance and extended service life.
Hastelloy C276 performs exceptionally well in environments rich in chlorides and oxidizing acids, providing strong protection against stress corrosion cracking and pitting. If your application primarily involves reducing media or general corrosive conditions, and cost is a key consideration, Hastelloy C276 is often an excellent choice.
By gaining a deep understanding of the microstructure and properties of these two alloys, industries can select the most appropriate material based on specific requirements, ensuring long-term stability and reliability of their equipment.
