UNS N07718 alloy is an agehardenable nickel-iron-chromium-columbium-molybdenumtitanium-aluminum alloy designed to combine excellent strength with good fabrication characteristics in the annealed condition. While limited to applications below 1200°F (650°C), it is significantly stronger at these lower temperatures than materials such as Waspaloy alloy, R-41 alloy, or X-750 alloy. It is also much easier to weld than these alloys, and is less susceptible to the strain age cracking problems common for gamma prime strengthened materials. 718 alloy is normally only used for component applications up to 1200°F (650°C); however, its oxidation resistance is comparable to that for other gamma-primestrengthened superalloys.
718 alloy is furnished in the solution heattreated condition unless otherwise specified. The alloy is normally solution heat-treated at 1700 to 1850°F (925 to 1010°C) and rapidly cooled or water quenched for optimal properties. Following solution heat treatment, the alloy is normally age-hardened by a two step treatment consisting of 1325°F (720°C) for 8 hours, furnace cooling to 1150°F(620°C), holding for an additional 8 hours, and then air cooling.
718 alloy is produced in the form of sheet, strip, plate, bar, billet, wire, and tubular products.
