Inconel 718 is an age-hardenable nickel–chromium superalloy with niobium. After ageing it keeps very high strength up to about 650 °C and resists corrosion well. It is welded more easily than most superalloys, but is hard to machine. It is used for jet engine parts, turbine discs and shafts, fasteners, oil and gas tools, and high-temperature springs.
Quick facts
- Type
- Precipitation-hardened nickel superalloy
- Nickel / chromium
- About 50–55% / 17–21%
- Niobium
- About 4.75–5.5%
- Tensile strength
- About 1,240 MPa or more after ageing
- Service temperature
- Up to about 650 °C for full strength
- Machinability
- Difficult: low speeds, rigid set-up, carbide or ceramic tools
Equivalent grades
| Standard | Grade |
|---|---|
| UNS | N07718 |
| W.Nr / EN | 2.4668 (NiCr19Fe19Nb5Mo3) |
| AMS | 5662, 5663 (bar), 5596 (sheet) |
Equivalents are close, not identical. Name the grade and standard on the drawing.
Inconel 718 or Inconel 625?
| 718 | 625 | |
|---|---|---|
| Strength | Much higher (age hardened) | Lower |
| Corrosion resistance | Good | Excellent |
| Heat treatment | Solution treat and age | Used annealed |
| Typical use | Rotating and load-bearing parts | Corrosive service, cladding |
Machining it
- Machine in the solution-treated state where possible, then age
- Low cutting speeds and steady feeds; avoid rubbing
- Rigid machines and sharp carbide or ceramic tools
- Plenty of coolant; tools wear fast
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Questions
- Why is Inconel 718 so hard to machine?
- It stays strong when hot and work hardens quickly, so the cutting edge sees high heat and force.
- Is 718 magnetic?
- It is essentially non-magnetic in normal use.
- Can Inconel 718 be welded?
- Yes, it is one of the more weldable superalloys, usually welded before ageing.
The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 29 October 2026.