Inconel is Special Metals' trademarked family of nickel-chromium-based superalloys, prized for holding onto strength and resisting corrosion and oxidation at temperatures where most metals lose their structural integrity — properties that make the family a staple in jet engines, gas turbines, and chemical processing equipment. The grade cataloged here as Inconel 22 shares the same base chemistry as the widely known Hastelloy C-22 (UNS N06022), a nickel-chromium-molybdenum-tungsten alloy rather than the simpler nickel-chromium-iron chemistry of the classic 600-series grades.

The addition of roughly 13% molybdenum and 3% tungsten alongside 20-22.5% chromium gives this alloy outstanding resistance to both oxidizing and reducing chemical environments, including hot contaminated media that would attack other nickel alloys. Its low carbon content minimizes carbide precipitation at grain boundaries during welding, preserving corrosion resistance in the heat-affected zone. That combination has made it a preferred choice for flue-gas desulfurization systems, chemical process piping, and pollution-control equipment handling aggressive acids.

From a shop-floor perspective, this grade sits at the demanding end of the nickel-superalloy spectrum. The heavy molybdenum and tungsten content that gives it such broad corrosion resistance also raises cutting forces and heat generation well above what's seen on the solid-solution 600 and 601 grades, so tooling and parameters need to be selected accordingly.

Nickel-based superalloys are difficult to cut for a consistent set of reasons, and this Mo-W-rich grade shows all of them at their most pronounced. Thermal conductivity is roughly a third that of carbon steel, so the heat generated in the shear zone can't escape into the chip or workpiece the way it does with steel — it concentrates right at the cutting edge instead, driving up tool-tip temperatures and accelerating diffusion and notch wear.

The alloy also work-hardens aggressively under the mechanical and thermal stress of cutting, forming a hardened layer at the machined surface that the next pass has to cut through. Light cuts, dull edges, or interrupted engagement all make this worse, so maintaining a constant chip load and keeping the tool cutting below the previously work-hardened layer are both important. Unlike hardened tool steel, which softens as it heats up, nickel superalloys retain much of their strength and hardness at elevated temperature, meaning the tool doesn't get any help from thermal softening the way it would on most steels.

Finally, this chemistry is prone to galling and built-up edge because the workpiece material tends to adhere to the cutting edge under pressure and heat, particularly on uncoated or poorly polished inserts. Sharp, positive geometries with a polished rake face, rigid low-vibration setups, and generous coolant flow all help manage these effects. Compared with precipitation-hardened Inconel grades like 718, this solid-solution alloy is somewhat more forgiving, but it remains one of the tougher members of the Inconel-family catalog to machine economically.