What is the difference between Hastelloy C276 and C22?

What is the difference between Hastelloy C276 and C22?
The main difference between Hastelloy C22 and C276 is that Hastelloy C22 is important because of its enhanced versatility and excellent resistance to chloride-induced pitting, while Hastelloy C276 is important because of its proven performance in a wide range of corrosive chemicals.

What is Hastelloy C276?
Alloy C276 is a nickel-chromium-molybdenum solution-strengthened superalloy, considered the most versatile corrosion-resistant alloy, with a nominal chemical composition of 57% nickel, 16% chromium, and 16% molybdenum, with additions of iron, tungsten, and cobalt. It is commonly referred to by the trade name Hastelloy® C276 and the generic name UNS N10276.C276 is commonly used in extremely corrosive environments that other alloys cannot withstand. HASTELLOY C276 has excellent resistance to strong solutions of oxidizing salts, such as ferric chloride and copper chloride.

Hastelloy C276 Properties
Corrosion resistance

Alloy C276 is one of the most corrosion-resistant alloys. The nickel, chromium, and molybdenum found in alloy C276 pose a powerful triple threat to virtually all forms of corrosion.C276 has excellent resistance to reducing and oxidizing acids, including sulfuric, hydrochloric, and acetic acids. It also performs well in seawater, chlorides, wet chlorine gas, oxidizing salts, and hypochlorites. The molybdenum and tungsten content protects against various forms of localized corrosion, including pitting, crevice corrosion, and chloride stress corrosion cracking C276 has excellent oxidation resistance at elevated temperatures up to 1900° F (1038° C) C276 is not recommended for use in extreme oxidizing environments, such as those presented by concentrated hot nitric acid.

High-Temperature Resistance

C276 resists oxidation at temperatures up to 1900°F (1038°C).
Mechanical Properties

The yield strength of C276 is 41(345 MPa) under annealed conditions. However, higher strengths can be obtained by the pilger process, and C276 maintains excellent toughness at low temperatures.

What is C22 material?
Alloy C22 is a nickel-chromium-molybdenum solution-strengthened superalloy with a nominal chemical composition of 56% nickel, 22% chromium, and 13% molybdenum, with additions of iron, tungsten, and cobalt. It is commonly referred to by the trade name Hastelloy® C22 and the generic name UNS N06022. C22 offers excellent corrosion and oxidation resistance, outstanding mechanical properties over a wide temperature range, and good fabrication properties.

Hastelloy C22 Properties
Corrosion Resistance

Alloy C22 is one of the most corrosion-resistant alloys, even better than C276 and 625. It is resistant to almost all reducing and oxidizing environments, including strong oxidizing agents, seawater, and organic acids. In addition, C22 has excellent resistance to localized corrosion caused by chlorides, including pitting, crevice corrosion, and stress corrosion cracking.

Oxidation Resistance
C22 has excellent resistance to oxidation, carburization, and sulfidation at elevated temperatures. However, due to the potential formation of embrittled phases, C22 should not be used at temperatures above 1250°F.

Mechanical Properties
C22 is normally supplied under annealed conditions with a minimum yield strength of 45. however, C22 can be cold-worked to higher strength levels.

Heat Treatment
C22 is typically annealed at 2050°F (1121°C), followed by rapid cooling.

Machinability
C22 can be hot or cold worked. However, C22 hardens quickly. Therefore, cold working must always be done in stages with annealing in between. Parts should be annealed after cold working.

Areas of application for the two Hastelloy materials
C276 is widely used in the oil and gas industry and is a mainstay of the chemical processing industry because of its resistance to corrosion in a wide range of aggressive substances. In upstream oil and gas, C276 is used as tubing, casing, or liner pipe in corrosive sour service environments characterized by high levels of H 2 S, CO 2, and chlorides. It is also used in other industries that encounter harsh environments, including the pharmaceutical and paper industries. c276 is used in valves for cryogenic applications and has been used in superconductors for temperatures as low as -455°F (-271°C).

C22’s excellent corrosion resistance facilitates its use in many different markets, wherever harsh environments are encountered, including the chemical process, pharmaceutical, food processing, oil and gas, power generation, and paper industries.