Alloy C22 is a nickel-chromium-molybdenum solid solution reinforced 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 as Hastelloy C22 and generic name UNS NO6022.

Hastelloy C22 is a general purpose nickel-chromium-molybdenum-tungsten austenitic alloy with increased resistance to pitting, crevice corrosion and stress corrosion cracking. The high chromium content gives good oxidation resistance to oxidizing media, while the molybdenum and tungsten content gives good oxidation resistance to reducing media.

Hastelloy C22 also has excellent resistance to oxidizing aqueous media, including wet chlorine and mixtures containing nitric acid or oxidizing acids with chloride ions.

Hastelloy C22 should not be used at service temperatures above 1250°F due to formation of harmful phases above this temperature.