The dynamic recrystallization evolution and kinetics of Ni–18.3Cr–6.4Co–5.9W–4Mo–2.19Al–1.16Ti superalloy during hot deformation

The dynamic recrystallization (DRX) behavior of Ni–18.3Cr–6.4Co–5.9W–4Mo–2.19Al–1.16Ti superalloy was investigated by means of isothermal compression tests in the temperature range of 1010–1160 °C and strain rate range of 0.001–1 s−1. It was found that the nucleation mechanisms of discontinuous DRX and continuous DRX (CDRX) occurred simultaneously during hot deformation, and twinning can play an important role in improving the process of DRX. There are three stages in the process of CDRX, i.e., the accumulation and rearrangement of dislocations, the formation of subgrain boundary, and the conversion to high angle grain boundaries (HAGBs) from subgrain boundary. Moreover, the effect of CDRX grows weaker with increasing deformation temperature and decreasing strain rate. Additionally, both the volume fraction of DRX grains and the DRX grain size were closely related to the deformation temperature and strain rate, and a power exponent relationship between the DRX grain size andZparameter was obtained. Based on the experimental data, the kinetic equations were also developed to evaluate the volume fraction of DRX grains during hot deformation in the alloy.