Alloy 718 INCONEL® 718 – W. Nr. 2.4668 / UNS N07718 / ASTM B637, B670, B906

Alloy 718 INCONEL® 718

Alloy 718 INCONEL® 718 is a highly corrosion-resistant, high-temperature nickel -chromium alloy with excellent mechanical strength, high machinability, and excellent weldability. It can be used over a temperature range from -423°F (-253°C) to 1300°F (704°C).

This alloy is particularly appreciated for its ability to maintain high mechanical properties thanks to precipitation hardening of secondary phases (gamma prime and gamma double-prime). The excellent combination of fatigue , tensile , creep , and creep rupture resistance makes it ideal for applications in the aerospace, nuclear, and oil & gas sectors .

Reference standards:

  • ASTM B637 (bars and forgings)
  • ASTM B670 (sheet and strip)
  • ASTM B906 (plates and sheets)

Chemical composition (%)

Element Content (%)
Nickel (Ni) + Cobalt (Co) 50.00 – 55.00
Chromium (Cr) 5:00 PM – 9:00 PM
Iron (Fe) Balanced
Niobium + Tantalum (Nb+Ta) 4.75 – 5.50
Molybdenum (Mo) 2.80 – 3.30
Titanium (Ti) 0.65 – 1.15
Aluminum (Al) 0.20 – 0.80
Cobalt (Co) 1.00 max
Carbon (C) 0.08 max
Manganese (Mn) 0.35 max
Silicon (Si) 0.35 max
Phosphorus (P) 0.015 max
Sulfur (S) 0.015 max
Boron (B) 0.006 max
Copper (Cu) 0.30 max

Mechanical properties

Temperature (°C) Tensile strength (MPa) Yield strength (MPa) Elongation (%)
20 1240 – 1515 825 – 1035 12 – 20
600 1035 720 16
800 880 665 15
1000 750 560 10

Heat treatments

INCONEL® 718 is a precipitation-hardenable alloy. The main thermal cycles used to optimize mechanical properties are:

  1. Solution annealing at 1700-1850°F (925-1010°C), followed by rapid cooling and subsequent aging at:
    • 1325°F (720°C) for 8 hours, oven cooling to 1150°F (620°C) for a total of 18 hours, followed by air cooling.
  2. Solution annealing at 1900-1950°F (1038-1065°C), followed by rapid cooling and subsequent aging at:
    • 1400°F (760°C) for 10 hours, oven cooling to 1200°F (650°C) for a total of 20 hours, followed by air cooling.

Available formats

INCONEL® Alloy 718 is available in the following forms:

Industrial applications

Thanks to its combination of mechanical and corrosion resistance, INCONEL® 718 finds application in various sectors:

  • Aerospace and Defense: Aircraft engine turbine components, jet engine exhausts, propulsion systems, and rockets.
  • Power Generation: Heat exchangers, gas and steam turbine plants.
  • Chemical and Pharmaceutical Industry: Components for chemical reactors and systems operating in high temperatures and corrosive environments.
  • Motorsport: Critical components for racing engines and high-performance exhausts.
  • Nuclear: Structural materials for nuclear reactors, control rods and steam generator piping.
  • Oil & Gas: Deep-hole drilling components, pipelines, and fittings resistant to marine environments and high pressures.

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