High-temperature compression and electron backscatter diffraction (EBSD) techniques were used in a systematic investigation of the dynamic recrystallization (DRX) behavior and texture evolution of the Inconel625 alloy. The true stress–true strain curves and the constitutive equation of Inconel625 were obtained at temperatures ranging from 900 to 1200 °C and strain rates of 10, 1, 0.1, and 0.01 s−1. The adiabatic heating effect was observed during the hot compression process. At a high strain rate, as the temperature increased, the grains initially refined and then grew, and the proportion of high-angle grain boundaries increased. The volume fraction of the dynamic recrystallization increased. Most of the grains were randomly distributed and the proportion of recrystallized texture components first increased and then decreased. Complete dynamic recrystallization occurred at 1100 °C, where the recrystallized volume fraction and the random distribution ratios of grains reached a maximum. This study indicated that the dynamic recrystallization mechanism of the Inconel625 alloy at a high strain rate included continuous dynamic recrystallization with subgrain merging and rotation, and discontinuous dynamic recrystallization with bulging grain boundary induced by twinning. The latter mechanism was less dominant.
Dynamic recrystallization (DRX) and grain growth behaviors of Inconel 625 alloy are investigated via hot compression test in the temperature range of 900–1200 °C and strain rate range of 0.01–10 s−1. The electron backscatter distribution technique is an effective method for identifying twin boundary evolution on the basis of temperature and strain rate; this approach is applied in this study to investigate the effects of twins on the DRX process and grain growth. The fraction of DRX increases with temperature under all strain rates, but the strain rate exerts a complex effect on DRX. Grain size variation with temperature follows a similar trend of declining and then increasing, whereas no apparent trend is observed at various strain rates. The DRX mechanism of the Inconel 625 alloy shifts from discontinuous DRX to continuous DRX with a reduction in deformation temperature and increase in strain rate. The fraction of Σ3n (n = 1, 2, 3) boundaries (twin boundaries) increases with increasing temperature at low temperatures (<1100 °C), but declines with increasing temperature at high temperatures (≥1100 °C). At low temperatures (<1100 °C), the fraction of Σ3n (n = 1, 2, 3) boundaries declines with an increasing strain rate up to 1 s−1 and then increases.
Texture evolution and dislocation behavior of Ni‐based superalloys at various temperatures and strain rate of 1 s−1 are studied using electron backscatter diffraction (EBSD) technique and transmission electron microscope (TEM). It can be concluded that no significant texture is formed at high deformation temperature, especially for the occurrence of completed dynamic recrystallization (DRX). In addition, texture weakening is easy to realize by conducting DRX process on the Ni‐based superalloys, whereas a slight strengthening is observed during grain growth. Based on the TEM images, the original grain boundary with high orientation gradient at low temperature provides an excellent position for DRX nuclei, which is strongly related with the dislocation motion. Moreover, it is concluded that the dislocation behavior plays a significant role in the plastic deformation of the Ni‐based superalloys. Herein, theoretical guidance for the application of nickel‐based superalloys and furthermore enhancement of their plastic deformation properties is provided.
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