Investigation on the influences of δ phase on the dynamic recrystallization of Inconel 718 through a modified cellular automaton model

Abstract

The dynamic recrystallization (DRX) behavior of Inconel 718 containing δ phase was investigated through the isothermal compression experiments and cellular automaton (CA). The compression experiments were conducted under the deformation temperature of 980Co and strain rates of 0.01, 0.1, 1s−1. A modified CA model was established to investigate the DRX for Inconel 718 alloy with δ phase, by which the influences of size, volume fraction and shape of δ phase on DRX behavior of the alloy were investigated. One commercial Ni-based superalloy with 5.40% Nb and the other with 5.27% Nb were used to investigate the influences of δ phase content on DRX, and the various pre-treatments were carried out to investigate the influences of δ phase size and morphology on DRX. The results obtained by the developed CA model show a great agreement with the physical results, which indicates that the modified CA model could be used to describe the DRX phenomenon with δ phase. The results show the smaller size and rod-like δ phase make the DRX fraction increase faster. Little difference for the studied alloy with the various particle fractions in DRX curves at early stage and faster DRX fraction rising for the alloy with higher particle fraction at later stage are shown. Compared with the alloy with rod-like δ phase, the strain reaching entire DRX fraction is larger for the alloy with needle-like δ phase. The finer grain size can be obtained for the studied alloy with smaller δ phase size after the deformation stage.