Inconel 718
Pick when: high-temp aerospace
Gas-turbine hot-section parts, cryogenic LH2 hardware, fasteners that must hold strength at 650 °C. Age-hardenable to 1380 MPa. Machinability is the worst of the three.
Common AMS: 5662, 5663, 5596
Engineering library
Engineering · Comparison
Inconel 718 vs Hastelloy C-276 vs Monel 400.
Three nickel-based alloys, three different applications. Picking between them comes down to which environment the part has to survive — high temperature, aggressive chemistry, or seawater — and what the cost ceiling is.
Inconel 718
High-temp strength
Hastelloy C-276
Aggressive chemistry
Monel 400
Seawater + cost
| Property | Inconel 718 | Hastelloy C-276 | Monel 400 |
|---|---|---|---|
| UTS (annealed) | ~930 MPa | 790 MPa | 550 MPa |
| UTS (aged / hardened) | 1380 MPa (aged) | — | — |
| Density | 8.19 g/cc | 8.89 g/cc | 8.80 g/cc |
| Max service temp | 700 °C (1300 °F) | 1038 °C | 535 °C |
| Cost ($/lb, Q1 2026) | $35–50 | $50–80 | $15–25 |
| Machinability vs B1112 | 12 | 18 | 35 |
| Pitting / crevice resistance | Good | Best-in-class | Moderate |
| Galling tendency | Moderate | Low | High |
| Magnetic | Slightly | No | Slightly |
Hastelloy C-276
Pick when: aggressive chemistry
Chemical processing, flue-gas scrubbers, high-temp seawater, exhaust hardware. Best pitting/crevice corrosion resistance of the three. Most expensive, but the price is justified when chloride or sulfur is present.
Common AMS: 5750
Monel 400
Pick when: marine + cost
Seawater pumps, valve trim, propeller shafts, marine fasteners. ~2× cheaper than Inconel and ~3× cheaper than Hastelloy. Loses strength above 535 °C and isn’t as corrosion-resistant as Hastelloy in oxidizing acids.
AMS 4675 (bar) · ASTM B164 · QQ-N-281
Decision rule
Three questions in order.
- 1. Will it operate above 535 °C (1000 °F)?
If yes, Monel is out. Inconel 718 holds usable strength to ~700 °C (1300 °F); Hastelloy C-276 resists oxidation/scaling up to ~1038 °C but, as a solid-solution alloy, loses strength well below that — pick it for corrosion at temperature, not load-bearing high-temp duty.
- 2. Will it see chlorides, mixed acids, or chemical-processing chemistry?
If yes, Hastelloy C-276 is the answer. Inconel 718 handles oxidizing environments well but is weak against reducing acids; Monel handles deaerated seawater but not aggressive chemistry.
- 3. Is cost the constraint and the environment is benign?
Monel 400. Especially for marine work where its galvanic compatibility with copper alloys avoids dissimilar-metal issues.
Keep exploring
Related tools & references
Inconel 718 datasheet→
The high-temp, age-hardenable superalloy in detail.
Hastelloy C-276 datasheet→
Best-in-class chloride and acid corrosion resistance.
Monel 400 datasheet→
The seawater-and-cost nickel alloy in detail.
How to machine Inconel 718→
Tooling and strategy for the hardest of the three to cut.
How to machine Hastelloy C-276→
Work-hardening and feed strategy for C-276.
How to machine Monel 400→
The most machinable of the three nickel alloys.
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