Constitutive modeling and dynamic recrystallization mechanism elaboration of FGH96 with severe hot deformation

Abstract

FGH96 nickel-based superalloy is widely used in manufacturing high-temperature components of aero engine, and welded by inertia friction welding (IFW). The materials welded by IFW suffer high temperature just below melting point and strain rate above 10 s−1. The deformation behavior and microstructures of FGH96 at severe deformation conditions are not sufficiently studied. In this paper, hot compression experiments with temperature of 1273–1473 K and strain rate of 0.01–30 s−1 were carried out to analyze the deformation behavior and dynamic recrystallization (DRX) of FGH96. Different from low strain rate researches, the continuous dynamic recrystallization was found complete and dominant at high strain rate and inferred to be stress driven. Two strain modified viscoplastic constitutive models which cover different DRX mechanisms were established by polynomial fitting or defining strain factor. The flow stresses calculated by both constitutive models were in good agreement with the experimental results. The finite element simulation application showed that the two constitutive models can accurately reflect the deformation behavior, and are suitable for the numerical simulation of IFW.