Effect of post-forging heat treatment on the microstructure and mechanical properties of a nickel-base superalloy SDZhS-15

Abstract

The newly designed ingot-metallurgy Ni-base superalloy SDZhS-15 intended for disc applications was subjected to multiple heat treatment and forging in the temperature range (Ts-70)-Ts, where Ts is the γ’ solvus temperature, followed by solid solution treatment and ageing. A fine-grained microstructure was attained in the forged condition as a result of recrystallization processes occurring during processing. It was revealed that solution treatment at T>(Ts-50) led to a fast γ grain growth, which in turn led to a decrease in strength and ductility of the superalloy. At the same time, the solution treatment at slightly lower temperatures, at (Ts-60)-(Ts-50), allowed to save fine γ grains (d γ = 10-20 μm) and to provide the formation of secondary γ′ precipitates with a mean size of about 0.1 The superalloy in the forged and heat treated condition showed superior mechanical properties as compared with those of other disc superalloys.