AMS 5664 is a designation of Nickel Inconel 718, itself a nickel-chromium alloy with high strength, corrosion and oxidation resistance, and excellent tensile and impact strength at cryogenic temperatures.
Full chemical composition is 52.5Ni – 19Cr – 3.0Mo – 5.1Cb – 0.90Ti – 0.50Al – 18Fe.
This designation is made by solution annealing at 1950°F (1065°C) followed by rapid cooling, usually in water, and precipitation hardening is done at 1400°F (760°C) for 10 hours and furnace cool to 1200°F (650°C), then aging at the same temperature for 20 hours.
It is available as bar, forging and ring, and is best suited for rotating and structural parts requiring high strength at cryogenic temperatures, as well as for short-time service up to 1000°F (538°C) and oxidation resistance up to 1800°F (982°C).
Efficiency when welding is about 100% with the gas tungsten-arc process and using the proprietary Nickel Filler Metal 718. Nickel Inconel 718 AMS 5664 can be age-hardened directly, without stress relief.