DAIKOFCW 622

The composition of the weld deposit, Ni-22Cr-13.5Mo-3W, is tailored to correspond to the nickel base alloy commonly referred to as alloy C22. The elevated molybdenum content mirrors alloys C276 and C4, but alloy C22 significantly improves performance in a broader range of oxidizing media by increasing chromium to 22%. Alloy C22 also furnishes a robust Nb-free weld metal suitable for dissimilar welds involving superaustenitic and superduplex stainless steels, or combinations of these with nickel base alloys. Some authorities prohibit or have ceased the use of alloy 625 consumables in such applications, where harmful Nb-rich precipitates may form in diluted or partially mixed regions around the fusion boundary. Applications of alloy C22 in highly corrosive environments encompass scrubbers for flue gas desulphurization (FGD), digesters and papermaking equipment, chemical process plants, corrosion-resistant overlays, and in severe offshore and petrochemical settings. Preheat is not typically required, with interpass temperature restricted to 100°C, and maintaining heat inputs below 1 kJ/mm is advisable.