Inconel vs Hastelloy vs Monel: Machining Differences

All three are nickel-based superalloys but their machining behavior differs enough to require different tool grades.

Composition Differences

• Inconel (e.g. 625, 718) — Nickel-chromium, hardens with heat treatment, work-hardens fast
• Hastelloy (e.g. C276, C22) — Nickel-molybdenum-chromium, exceptional corrosion resistance, very tough
• Monel (e.g. K500, 400) — Nickel-copper, more ductile than Inconel/Hastelloy, lower work-hardening

Machinability Rating (1212 steel = 100%)

Tool Selection

• Monel: PVD AlTiN carbide (M-grade), 60-100 m/min
• Inconel 718: Submicron carbide + AlTiN (S-grade KCS10B/S05F), 30-60 m/min carbide or 200+ m/min ceramic
• Hastelloy: Same as Inconel but reduce parameters 20%

Critical: HP Coolant

For all three, high-pressure coolant (1000+ PSI through internal-coolant tooling) drops cutting temp 200-300°C and triples tool life. See our Inconel turning guide.