Inconel 671 is a nickel-chromium alloy documented under UNS N06671, notable for a chromium level far above what is typical in the Inconel family. Active composition data places it at roughly 51.5% nickel and 48% chromium, a near even split rather than the 15-25% chromium range seen in most nickel-base superalloys used as bulk bar stock.

That high chromium loading is the reason Inconel 671 is used primarily as a corrosion-resistant weld overlay and cladding material rather than as a general-purpose structural alloy. In practice, it is deposited as a protective surface layer onto carbon steel or low-alloy steel components that must survive aggressive, high-temperature, chloride- and sulfur-bearing atmospheres, such as boiler tubing in pulp and paper recovery boilers and waste-to-energy furnaces. The overlay carries the corrosion and oxidation resistance while the steel substrate underneath carries the mechanical load. FM Carbide stocks Inconel 671 in machinable form for shops that need to face, turn, or mill overlay-clad or solid sections of this alloy, and the cutting data below reflects real parameters used for that purpose.

Machining Inconel 671 involves the same core challenges that make nickel-chromium superalloys difficult to cut, made more pronounced by its unusually high chromium fraction. The alloy's thermal conductivity is low compared with steel, so heat generated at the cutting edge does not dissipate efficiently into the chip or workpiece. Instead it concentrates at the tool-chip interface, driving up local temperatures and accelerating tool wear.

Nickel-chromium alloys also work-harden aggressively. Each pass leaves the freshly cut surface harder than the parent material, so a tool that dwells, rubs, or takes too light a cut ends up cutting into a harder layer on the next pass. This punishes light, hesitant cuts and rewards steady, adequate chip loads that get beneath the hardened layer rather than skating across it.

Because these alloys retain their strength and hardness at elevated temperatures, a property that makes them valuable in corrosion-resistant service, they do not soften the way ordinary steels do as cutting temperature rises. The tool cannot rely on thermal softening of the workpiece to ease the cut, so edge loads stay high for the full length of the pass. Nickel-rich alloys also have a strong chemical affinity for cobalt binders and coating materials, promoting galling, adhesion, and built-up edge, which accelerates notch wear and can trigger sudden edge chipping. Rigid setups, sharp and properly honed edges, adequate coolant, and grades engineered for heat-resistant alloys are essential for acceptable tool life.