When selecting high-performance nickel alloys for corrosive and extreme environments, Hastelloy C276 and Hastelloy C22 are two of the most widely used choices. Both belong to the Hastelloy C-series and offer outstanding corrosion resistance, but their chemical composition, performance characteristics, and ideal applications differ in important ways.

This article provides a detailed comparison of Hastelloy C276 vs Hastelloy C22 to help engineers, designers, and procurement professionals make informed material decisions.

Overview of Hastelloy C-Series Alloys

Hastelloy alloys are nickel-based superalloys known for their exceptional resistance to corrosion, high temperatures, and mechanical stress. The C-series is specifically designed for use in highly aggressive chemical environments, including acids, chlorides, and oxidizing media.

Among them, C276 is a long-established industry standard, while C22 is a more advanced alloy developed to deliver even broader corrosion resistance.

Chemical Composition Comparison

The most fundamental difference between Hastelloy C276 and C22 lies in their alloying elements.

Key takeaway:

• Hastelloy C22 has significantly higher chromium content, which greatly enhances resistance to pitting, crevice corrosion, and oxidizing environments.

• Hastelloy C276 has higher molybdenum, contributing to strong resistance in reducing conditions.

Corrosion Resistance: C276 vs C22

Hastelloy C276 Corrosion Resistance

Hastelloy C276 is well known for its ability to withstand:

• Reducing acids (hydrochloric, sulfuric)

• Chloride-containing environments

• Wet chlorine gas

• Stress corrosion cracking

It performs reliably in mixed chemical environments and remains one of the most versatile corrosion-resistant alloys available.

Hastelloy C22 Corrosion Resistance

Hastelloy C22 offers superior overall corrosion resistance, especially in:

• Strong oxidizing acids

• Pitting and crevice corrosion environments

• Chloride-induced corrosion

• Mixed oxidizing and reducing conditions

Thanks to its higher chromium content, C22 generally outperforms C276 in the most aggressive and unpredictable chemical processes.

Verdict:
👉 Hastelloy C22 provides broader and more robust corrosion resistance than C276.

Mechanical Properties and Fabrication

Both alloys share similar mechanical characteristics:

• Excellent toughness and ductility

• High strength at elevated temperatures

• Good weldability using standard techniques

• Suitable for cold and hot forming

However:

• Hastelloy C276 is often considered slightly easier to fabricate due to its long history and extensive fabrication data.

• Hastelloy C22 may require tighter process control but offers better long-term corrosion performance.

Typical Applications

Applications of Hastelloy C276

• Chemical processing equipment

• Heat exchangers

• Reactors and pressure vessels

• Pollution control and waste treatment systems

• Oil and gas components

Applications of Hastelloy C22

• Pharmaceutical and biotech processing

• Flue gas desulfurization systems

• Advanced chemical reactors

• Seawater and marine environments

• Highly corrosive mixed-acid systems

Cost and Availability

• Hastelloy C22 is generally more expensive than C276 due to higher chromium content and enhanced performance.

• C276 is more widely available and often chosen when cost is a major consideration and conditions are well understood.

Hastelloy C276 vs Hastelloy C22: Which Should You Choose?

Choose Hastelloy C276 if:

• You need proven performance in reducing environments

• Budget constraints are important

• The application has predictable corrosion conditions

Choose Hastelloy C22 if:

• Maximum corrosion resistance is required

• The environment involves both oxidizing and reducing agents

• Long-term reliability and safety are critical

Conclusion

In the comparison of Hastelloy C276 vs Hastelloy C22, both alloys are excellent choices for extreme environments, but they serve slightly different purposes. C276 remains a reliable, cost-effective workhorse, while C22 represents a higher-performance solution for the most aggressive corrosion challenges.

Understanding the chemical environment, mechanical requirements, and budget constraints is key to selecting the right alloy for your application.