Hastelloy is Haynes International's trademarked family of nickel-based corrosion-resistant superalloys, developed for chemical environments aggressive enough to attack standard stainless steels — strong acids, chlorides, and both oxidizing and reducing media used across chemical processing, pollution control, and pharmaceutical equipment. Hastelloy C-22 belongs to the C-family, which builds on the B-family's molybdenum-driven resistance to reducing acids by adding a substantial dose of chromium and tungsten alongside the molybdenum. That combination — roughly 20-22.5% chromium, 12.5-14.5% molybdenum, and 2.5-3.5% tungsten, on a nickel base — is what gives C-family alloys their signature trait: broad, general-purpose corrosion resistance across both oxidizing conditions (where chromium does the work) and reducing conditions (where molybdenum takes over).

C-22 in particular is prized for its resistance to localized attack — pitting, crevice corrosion, and stress-corrosion cracking — in oxidizing chloride environments such as ferric and cupric chlorides, wet chlorine, and mixed acid solutions where many other corrosion-resistant alloys struggle. It also holds up well against strongly oxidizing media like nitric acid mixtures. That versatility across such a wide range of aggressive chemistries makes it a common choice for scrubber systems, pickling and etching equipment, and process piping handling variable or blended process streams.

Hastelloy C-22 is a genuinely tough material to run efficiently. Its low thermal conductivity keeps the heat generated in the cut concentrated at the cutting edge instead of carrying it away in the chip, so tool temperatures rise quickly even at speeds that would be unremarkable on carbon or stainless steel. The alloy work-hardens under light or dwelling cuts, leaving a hardened skin behind the tool that resists the next pass — feed rates need to stay high enough that the insert is consistently cutting new, unworked material rather than skating across a hardened surface.

C-22 also has a strong tendency to gall and adhere to the cutting edge rather than shearing away cleanly, which shows up as built-up edge, chip welding, and accelerated flank wear when the tool isn't well matched to the material. A rigid setup that minimizes deflection and vibration, sharp positive-rake carbide geometry to keep cutting forces down, and a coating chosen for hot hardness and resistance to adhesion rather than pure wear resistance all pay off in tool life. Cutting speeds should stay low to moderate compared with steel, and a steady, adequately heavy feed — rather than light finishing passes — keeps the tool cutting productively and limits work-hardening between passes.