Abstract: A method of forming a component from a gamma-prime precipitation-strengthened nickel-base superalloy so that, following a supersolvus heat treatment the component characterized by a uniformly-sized grain microstructure. The method includes forming a billet having a sufficiently fine grain size to achieve superplasticity of the superalloy during a subsequent working step. The billet is then worked at a temperature below the gamma-prime solvus temperature of the superalloy so as to form a worked article, wherein the billet is worked so as to maintain strain rates above a lower strain rate limit to control average grain size and below an upper strain rate limit to avoid critical grain growth. Thereafter, the worked article is heat treated at a temperature above the gamma-prime solvus temperature of the superalloy for a duration sufficient to uniformly coarsen the grains of the worked article, after which the worked article is cooled at a rate sufficient to reprecipitate gamma-prime within the worked article.

Abstract: A rotor assembly for a turbine is provided. The rotor assembly includes a first portion of a rotor component forged from a first material. The first material is processed using a first process. The rotor assembly also includes a second portion of the rotor component separately forged from a second material that is the same material as the first material. The second portion is processed using a second process and is coupled to the first portion at a first axial position. A method for fabricating a rotor assembly for a turbine is also provided.