Inconel 718.
Aerospace superalloy.
Heat & strength.
Inconel 718 — nickel-chromium superalloy. Premium aerospace material. Strength up to 700°C. Used in turbine engines, exhaust systems, oil & gas.
Key principles.
Ni-Cr-Fe-Nb
55% Ni, 19% Cr, 18% Fe, 5% Nb, 3% Mo. Strengthened by Nb-rich precipitates.
UTS 1240 MPa
Yield 1050 MPa. Heat-treated condition. Aerospace-grade strength.
To 700°C
Strength retained to 700°C. Above, strength drops rapidly.
Excellent
Resists oxidation, stress corrosion cracking. Standard for aerospace exhaust.
Difficult
Work-hardens during cutting. Specialty tooling, slow speeds, expensive.
Premium
~$80-150/kg. Top-tier engineering metal.
FAQ
Inconel 718 vs 625?
718: precipitation-hardenable, higher strength via heat treat. 625: solution-strengthened, easier to weld.
Heat treatment?
Solution annealed + age-hardened. AMS 5662/5663 standard. Critical for full strength.
Major applications?
Aircraft turbine engine parts (compressor disks, turbine blades). Oil & gas downhole tools. Rocket engines.
Welding?
TIG, MIG with matching filler. Cracking-prone — controlled procedure required. Aerospace certification specific.
Machining tips?
Carbide tools, low speeds (15-30 m/min), high feed. Climb milling. Coolant-flooded. Tooling cost 5-10× aluminum.
Why so expensive?
Nickel commodity priced. Niobium small-source mineral. Aerospace-grade certification, melting, heat treat add cost.