Inconel is Special Metals' trademarked family of nickel-chromium-based superalloys, developed to keep their strength and resist corrosion and oxidation at temperatures where most other metals lose their structural integrity — a combination that has made the family a mainstay of jet engines, gas turbines, and chemical processing equipment. Inconel 600 is the original, classic grade in that family: a solid-solution-strengthened nickel-chromium-iron alloy first developed decades ago and still one of the most widely specified nickel alloys in industry today.

Because it isn't precipitation-hardened, 600 gets its strength purely from the nickel-chromium solid solution rather than from an aging heat treatment, which keeps its metallurgical behavior comparatively simple and consistent from heat to heat. Its high nickel content (72% minimum) gives it strong resistance to chloride-ion stress-corrosion cracking, a failure mode that plagues austenitic stainless steels, while the chromium content provides good resistance to oxidizing conditions and high-temperature scaling up to roughly 2000°F (1095°C).

These properties have made 600 a workhorse for chemical and food processing equipment, heat-treating fixtures and furnace components, nuclear reactor components, and various high-temperature springs, fasteners, and thermocouple protection tubes. It's not the strongest or most oxidation-resistant Inconel grade — later alloys like 601 and 603XL improved on high-temperature oxidation resistance specifically — but its broad corrosion resistance across a wide range of chemical environments keeps it in continuous demand.

Nickel-chromium-iron alloys like 600 machine very differently from steel, and the reasons come down to physics as much as chemistry. Thermal conductivity is roughly a third that of carbon steel, so instead of the chip carrying heat away from the cutting zone, that heat concentrates right at the tool tip, driving edge temperatures up fast and accelerating diffusion and notch wear on the insert.

The alloy also work-hardens noticeably under cutting forces, so a dull edge, an overly light cut, or excessive dwell time leaves a hardened skin on the surface that the next pass then has to cut through — which only accelerates wear further if it isn't accounted for. Unlike steel, which softens as it heats up during machining, 600 retains a large share of its room-temperature strength and hardness even as the cutting zone gets hot, so the tool doesn't get any assistance from thermal softening the way it would cutting most steels.

The material also tends to gall and adhere to the cutting edge under pressure, particularly with dull or poorly finished tools, which can lead to built-up edge and chipping rather than clean flank wear. Sharp, positive cutting geometries, rigid low-vibration setups, and steady feed rates that keep the tool cutting rather than rubbing all help control these effects. As a solid-solution alloy rather than a precipitation-hardened one, 600 is genuinely more forgiving to machine than grades like Inconel 718 or X-750, but it still demands tooling and technique suited to nickel superalloys rather than to steel or stainless.