Dynamic Softening Behavior of Ti-6.5Al-2Sn-4Zr-4Mo-1W-0.2Si Alloy with Lamellar Starting Microstructure during Hot Deformation

The high-temperature deformation behavior of Ti-6.5Al-2Sn-4Zr-4Mo-1W-0.2Si alloy with lamellar starting structure was investigated by carrying a series of isothermal compression tests at temperatures of 850-1030 °C and strain rates of 0.001-10 s −1 on the Gleeble-3500 simulator. Strain-rate sensitivity exponent and deformation activation energy have been analyzed associated with the dynamic softening behaviors. Meanwhile, different identification approaches like power dissipation distribution and work-hardening derivative have been adopted to identify the softening behaviors corresponding to different deformation parameters. Then constitutive models based on the dislocation evolution have been employed to characterize the flow curves of Ti-6.5Al-2Sn-4Zr-4Mo-1W-0.2Si alloy. Finally, microstructure observation has been carried out to verify the dynamic softening behaviors occurred under different deformation conditions.