Effect of ultrasonic energy field on plastic deformation behavior and microstructure evolution of Ti6Al4V alloy under room-temperature compression

The room-temperature compression tests of Ti6Al4V alloy are conducted under different ultrasonic vibration conditions. The effects of ultrasonic energy field and strain rate on the plastic deformation behaviors and microstructure evolution are carefully investigated. Moreover, by considering the effects of ultrasonic energy field, a modified Johnson-Cook (MJC) constitutive model and a deep-improved Johnson-Cook (DJC) constitutive model are constructed to represent the plastic deformation behaviors of Ti6Al4V alloy. The results indicate that the plastic deformation behaviors of Ti6Al4V alloy are remarkably affected by the ultrasonic energy field and strain rate. As the vibration amplitude rises or the strain rate decreases, the flow stress exerts a decrease trend. The introduction of ultrasonic energy field boosts the activation of $\left\{0001\right\}<11\overline{2}0>$ basal slip systems and the formation of soft orientation $<0001>$, which facilitates dislocation multiplication and uniform distribution of dislocations. Meanwhile, dislocation motion is enhanced, and dislocation cells are smoothly rearranged into subgrain boundaries, which further promotes the grain refinement. In addition, the progress of grain rotation is accelerated toward the soft orientation $<0001>$, which boosts the formation of $<0001>//\mathrm{ND}$ texture. By comparing the measured and predicted stress, both the MJC model and the DJC model show the good agreement to reproduce the plastic deformation behavior under different ultrasonic vibration conditions. However, the higher correlation coefficient (equals to 0.999) and the lower average absolute relative error (controlled in 4.27 %) indicate that the DJC model enjoys the superior prediction capability compared to the MJC model.