Influences of pre-precipitated 8 phase on microstructures and hot compressive deformation features of a nickel-based superalloy

Microstructural changes and flow characteristics of a nickel-based superalloy with pre-precipitated delta phases (Ni3Nb) are investigated using hot compressive experiments. The higher forming temperature or lower strain rate not only aggravate the arrangement/annihilation of dislocations, but also stimulate the generation/growth of substructures and dynamic recrystallization (DRX) grains. As the percentage of pre-precipitated delta phases is raised, the obvious work hardening behavior induced by the intense interactions between delta phases, grain boundaries and substructures occurs in the initial hot forming process. While the alloy is further strained, the DRX behavior are obviously promoted by delta phases. Considering the influences of pre-precipitated delta phases and forming parameters, an improved Hensel-Spittel-Carofalo (HSC) equation and an e-insensitive support vector regression (e-SVR) model are developed for reconstructing the flow features of the researched alloy. The minor deviations between the tested and forecasted true stresses indicate that the developed HSC model and e-SVR model can be properly utilized to characterize the hot forming features of the researched superalloy with different percentages of pre-precipitated delta phases.