Haynes 601 is Haynes International's trade name for the nickel-chromium-iron alloy more commonly sold as Inconel 601. It shares the same solid-solution-strengthened family as Haynes/Inconel 600, but with a deliberately different balance: less nickel (60.5% nominal versus 72%+ minimum for 600), more iron (14% versus 6-10%), and a distinguishing 1.4% aluminum addition that Haynes/Inconel 600 does not have.

That aluminum addition is the whole point of the alloy. Under oxidizing conditions it forms a tight, adherent, self-healing Al2O3 scale on top of the alloy's chromium oxide layer, giving Haynes 601 meaningfully better resistance to high-temperature oxidation than 600 — usable up to roughly 2200°F (1204°C). It is a general-purpose heat- and corrosion-resistant engineering alloy used for furnace muffles, radiant tubes, heat-treating baskets and fixtures, and other components that see prolonged cyclic exposure to oxidizing atmospheres at high temperature.

Haynes 601 machines similarly to Haynes 600, since both are solid-solution nickel-chromium-iron alloys without gamma-prime hardening — tough and gummy rather than hard and abrasive. Low thermal conductivity concentrates cutting heat at the tool-chip interface rather than letting it escape into the chip, so crater wear accelerates quickly once speeds run too high for the tool grade in use.

The higher iron content and aluminum addition in 601 give it slightly different work-hardening behavior than 600, but the practical machining response is the same family of problems: rapid strain hardening under light or interrupted cuts, a tendency to gall and build up on the cutting edge due to chemical affinity with common tool materials, and retained strength at elevated temperature that keeps tool edges under heavy load even as the cutting zone heats up. Rigid setups, sharp positive-rake coated carbide, constant chip loads, and generous coolant flow remain the standard approach.