Development of Udimet 720 for High Strength Disk Applications

Udimet 720 is a cast-wrought nickel base superalloy which was originally used for land based gas turbine blades. Work is being done to develop this alloy for high strength disks applications. Hot tensile tests were preformed to define temperature and strain rate parameters for conventional, hot die and superplastic forging. This information was used to select forging parameters for disk type pancakes. Heat treatments were developed to produce mechanical properties suitable for disks. Microstructure and hot tensile properties are reported for various heat treatments. Tensile and stress rupture properties of U720 compare favorably to high strength P/M disk alloys. The production of fine grained U720 billet by use of the VADER (Vacuum Arc Double Electrode Remelt) process offers the potential to produce large disks from a cast-wrought high strength superalloy.