Dynamic recrystallization mechanism of Ti-6554 alloy during high-temperature deformation

Abstract

Isothermal hot compression tests were carried out at a temperature range of 810–930 ℃ and a strain rate range of 0.001 s−1-10 s−1 to investigate the dynamic recrystallization (DRX) mechanism of Ti-6554 alloy during high-temperature deformation. The constitutive equation based on DRX was established. Optical microscopy (OM) and electron backscatter diffraction (EBSD) techniques were used to characterize the microstructure. The results showed that the developed constitutive equation based on DRX can effectively predict the flow stress of Ti-6554 alloy with a correlation coefficient of 0.995. High temperature and low strain rate are conducive to the development of DRX. The DRX mechanism is more dependent on the strain rate. At low strain rate, continuous DRX (CDRX) is dominant. With the increase of strain rate, the inhomogeneity of deformation leads to the occurrence of several DRX mechanisms simultaneously. Discontinuous DRX (DDRX) is often found near serrated grain boundaries. In addition, when the strain rate is increased to 10 s−1, the rare geometric DRX (GDRX) is detected, which is associated with the activation of deformation bands at high strain rate.