Is alloy C22 a Hastelloy?
Alloy C22 is a nickel-chromium-molybdenum solid 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 known by the trade name Hastelloy C22 and the generic name UNS N06022. C22 has excellent corrosion and oxidation resistance, excellent mechanical properties over a wide temperature range, and good fabrication properties.
Features
Corrosion Resistance
Alloy C22 is one of the most corrosion resistant alloys available, even better than C276 and 625. It resists nearly all reducing and oxidizing environments, including strong oxidants, seawater and organic acids. In addition, C22 has excellent resistance to chloride-induced localized corrosion, including pitting, crevice corrosion and stress corrosion cracking.
Oxidation Resistance
C22 has excellent resistance to oxidation, carburization and sulfidation at elevated temperatures. However, C22 should not be used at temperatures above 1250°F due to the potential for the formation of brittle phases.
Mechanical Properties
C22 is typically supplied in the annealed condition with a minimum yield strength of 45 ksi. However, C22 can be cold worked to higher strength levels.
Heat Treatment
C22 is typically annealed at 2050°F (1121°C) and then rapidly cooled.
Machinability
C22 can be hot worked or cold worked. However, C22 work hardens rapidly. Therefore, cold working must usually be done in stages with anneals in between. Parts should be annealed after cold working.
