In industries that face highly aggressive chemical environments, material selection is a crucial decision that directly affects safety, durability, and cost. Two alloys that are frequently compared for such demanding applications are Alloy 20 and Hastelloy C276. Both are renowned for their corrosion resistance, but they are optimized for different conditions. This article provides a detailed corrosion comparison of Alloy 20 vs Hastelloy C276 to help you make an informed choice for your project.
What is Alloy 20
Alloy 20, also known as Carpenter 20, is an iron based austenitic alloy that contains significant amounts of nickel, chromium, molybdenum, and copper. It was originally developed for sulfuric acid service but is also resistant to a wide range of aggressive media.
Key characteristics of Alloy 20 include
Nickel content of about 32 to 38 percent which enhances corrosion resistance
Chromium content of about 19 to 21 percent for oxidation resistance
Copper content of about 3 to 4 percent which improves resistance to sulfuric acid
Molybdenum content of about 2 to 3 percent for pitting and crevice corrosion resistance
What is Hastelloy C276
Hastelloy C276 is a nickel molybdenum chromium alloy with added tungsten. It is considered one of the most corrosion resistant alloys available for severe chemical service.
Key characteristics of Hastelloy C276 include
Nickel content of over 57 percent which provides excellent corrosion resistance
Molybdenum content of about 15 to 17 percent for enhanced resistance to pitting and crevice corrosion
Chromium content of about 14 to 16 percent for improved oxidation resistance
Tungsten content of about 3 to 4 percent which adds strength and protection in reducing environments
Corrosion resistance comparison
Sulfuric acid
Alloy 20 was designed specifically for sulfuric acid environments. It performs very well in concentrations up to about 60 percent at moderate temperatures. It provides a cost effective solution where sulfuric acid is the primary concern.
Hastelloy C276 is resistant to sulfuric acid but is not optimized for it. In sulfuric acid environments where Alloy 20 is suitable, Hastelloy C276 is often considered excessive in terms of cost and capability.
Hydrochloric acid
Hastelloy C276 is one of the few alloys that can withstand hydrochloric acid across a broad range of concentrations and temperatures. Alloy 20 is not recommended for hydrochloric acid and is subject to rapid attack.
Chloride environments
Alloy 20 offers good resistance to chloride stress corrosion cracking but can be vulnerable to pitting in highly concentrated chloride solutions.
Hastelloy C276 provides excellent resistance to pitting and crevice corrosion even in aggressive chloride conditions.
Mixed chemical environments
Alloy 20 is effective in moderately oxidizing and reducing environments but not ideal for strong oxidizers like nitric acid.
Hastelloy C276 performs well in both oxidizing and reducing environments which makes it a more versatile choice for mixed chemical service.
Strength and fabrication
Both Alloy 20 and Hastelloy C276 offer good mechanical strength at room temperature. Alloy 20 typically provides slightly higher yield strength. Hastelloy C276 retains its properties better at elevated temperatures.
In terms of fabrication Alloy 20 is easier to work with. It can be welded using standard procedures and generally does not require post weld heat treatment. Hastelloy C276 can be welded but requires more care and often post weld cleaning to preserve its corrosion resistance.
Cost comparison
Alloy 20 is less expensive due to its lower nickel and molybdenum content. It is often chosen where its corrosion resistance is sufficient for the environment.
Hastelloy C276 is more costly but provides unmatched corrosion protection where failure would have significant safety or financial consequences.
Applications
Alloy 20 typical uses
Sulfuric acid storage and processing equipment
Chemical processing vessels and piping
Pharmaceutical and food processing
Heat exchangers and pump components handling acid
Hastelloy C276 typical uses
Pulp and paper industry bleach plants
Waste treatment and pollution control systems
Chemical processing under severe conditions
Flue gas scrubbers and heat exchangers exposed to aggressive media
Marine components exposed to seawater
How to choose between Alloy 20 and Hastelloy C276
Consider the following factors when selecting between these alloys
If sulfuric acid is the primary chemical Alloy 20 is often sufficient and more cost effective
If the environment involves hydrochloric acid chlorides or mixed aggressive chemicals Hastelloy C276 is the better option
For higher temperature applications Hastelloy C276 offers better retention of properties
If fabrication ease and lower cost are priorities Alloy 20 is advantageous
Working with a trusted supplier like sasaalloy ensures you get material that meets your project’s technical and economic requirements
The role of sasaalloy
At sasaalloy we supply Alloy 20 Hastelloy C276 and other high performance alloys in forms including pipe fittings flanges and custom fabrications. Our materials come with full certification and traceability and we provide expert guidance to help customers choose the best solution for their applications.
Conclusion
When comparing Alloy 20 vs Hastelloy C276 in terms of corrosion resistance the choice depends on the specific environment and application
Alloy 20 is ideal for sulfuric acid and moderately aggressive environments where cost control is important
Hastelloy C276 provides superior performance in chloride rich mixed acid and high temperature environments where failure is not an option
By understanding the strengths of each material and aligning them with your service conditions you can ensure long term safety and reliability
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Post time: Jul-01-2025