Introduction:
Alloy C-22 was introduced in 1982 as an improved development of the previously mentioned high-molybdenum Ni-Cr-Mo alloys. Considering that the earlier alloys (Hastelloy C-276 and C-4) had relatively low chromium content (around 16%) and that C-4 contained no tungsten, resulting in reduced corrosion resistance in certain media, the newly developed C-22 alloy increased the chromium content to about 21%, decreased nickel to about 13%, and added an appropriate amount of tungsten (approximately 3%). This balanced the levels of chromium, molybdenum, and tungsten in the alloy. Due to these characteristics, C-22 exhibits superior corrosion resistance in many environments compared to the previous Ni-Cr-Mo(W) alloys. Its advantages are particularly notable in oxidizing media such as FeCl₃, CuCl₂, wet chlorine, and oxidizing-reducing acids. At the same time, C-22 maintains excellent resistance to pitting, crevice corrosion, and stress corrosion cracking. With very low carbon and sulfur content, this alloy is highly suitable for corrosion-resistant welded equipment, vessels, and pipelines in the chemical industry without the risk of sensitization.

Applications:
Alloy 00Cr21Ni57Mo13W3 is a relatively new corrosion-resistant alloy. It is mainly used in seawater, acetic acid, acetic anhydride, chloride and fluoride systems, as well as in pickling equipment for phosphoric and mixed acid production, plate heat exchangers, SO₂ cooling towers, and other applications requiring resistance to general corrosion, pitting, and crevice corrosion. It is particularly suitable for media containing both high levels of chloride ions and strong oxidizing agents.