Microstructure and mechanical properties of a novel polycrystalline rhenium-containing nickel-based disc superalloy subjected to hot forging

Abstract

A newly developed heavy alloyed polycrystalline nickel-based superalloy SDZhS-15 containing rhenium and intended as a structural material for turbine discs in gas turbine engines has been studied. Multiple homogenization and heterogenization heat treatment was developed for the superalloy to improve its hot workability. The heat treated workpieces were subjected to single-step hot forging under quasi-isothermal conditions at temperatures slightly below the γ′ solvus temperature followed by air cooling and ageing. As a result, sound forgings with an inhomogeneous, partially recrystallized microstructure were produced. The obtained forgings were used for preparation of specimens for mechanical testing. The new superalloy showed superior high strength and high temperature capability, while retaining reasonable ductility in comparison with currently known disc superalloys.