Precipitation behavior during high-temperature isothermal compressive deformation of Inconel 718 alloy

Abstract

The precipitation behaviors of γ″ and δ phases during high-temperature isothermal compressive deformation of Inconel 718 alloy are investigated under the strain rate of 2.2·10 -4 s -1 . It is found that the precipitation behaviors are tailored by deformation temperatures, and lead to the disparately abnormal deformation characteristics. Under the deformation temperature of 800 o C, the microstructure is composed of incoherent needle-shaped γ″ precipitates at grain boundaries and ultrafine spherical γ″ particles within grains, resulting in the exceptional decrease of flow stress with absence of DRX. When deformed at 900 o C, it becomes needle-shaped δ precipitates at grain boundaries and intragranular disc-shaped γ″ precipitates, and the DRX softening degree is lowered consequently.

A new dynamic recrystallization kinetics model for a Nb containing Ni-Fe-Cr-base superalloy considering influences of initial δ phase

“…Jiang et al [32] analyzed the evolution of twins and substructures in hot deformation, and found that the dominant nucleation mechanism for Inconel 617B superalloy is original grain boundary bulging at low strain rates. Zhang et al [33] discussed the influences of γ′′ and δ phases on the high-temperature deformation behavior of Inconel 718 superalloy. Mei et al [34] discussed analyzed the effects of cold rolling on the precipitation and the morphology of δ-phase in Inconel 718 alloy.…”

Artificial Neural Network-Based Constitutive Relationship of Inconel 718 Superalloy Construction and Its Application in Accuracy Improvement of Numerical Simulation

“…In these tests, a computer control automatic data acquisition system was applied to monitor the experimental data continuously. The recorded normal stress and normal strain were converted into the homologous true stress and true strain according to the formulae in Equations (1) and (2).…”

“…ε T = ln(1 + ε N ) (2) where ε N and ε T are respectively the nominal strain and true strain, σ N and σ T are the nominal stress and true stress [21].…”

“…Inconel 718 is a typical nickel-based superalloy extensively applied in aero engines and gas turbines due to its superior corrosion resistance, oxidation resistance, heat resistance and high strength, creep strength [1][2][3]. Exactly because of its high strength and outstanding heat-resistance, it is a hard issue to process Inconel 718 superalloy under low temperature.…”

“…Exactly because of its high strength and outstanding heat-resistance, it is a hard issue to process Inconel 718 superalloy under low temperature. However, the flow behaviors of Inconel 718 superalloy become extremely complicated under elevated temperature not only due to concomitant hardening and softening behaviors, which mainly include three metallurgical phenomena: work hardening (WH) as well as the subsequent dynamic recovery (DRV) and dynamic recrystallization (DRX) [4][5][6][7] but also due to the precipitation and dissolution of the three different intermetallic precipitation phases, namely γ', γ" and δ phases [2]. The flow behaviors of materials are generally described by constitutive relationship: the intrinsic relationship among the process variables such as stress, strain, strain rate and temperature.…”