Multiple Deformation Mechanisms of a Metastable beta Ti-V Alloy at High Strain Rates

Dynamic compressive properties, microstructure evolution and deformation modes of binary Ti-16V alloys have been investigated. Mechanical tests were performed on the split Hopkinson pressure bar. In addition, optical microscopy, electron backscatter diffraction technique and transmission electron microscopy were applied to observe deformed microstructures. The results show that flow stress and strain hardening rate are both insensitive to loading strain rates. Critical instability strain rate of Ti-16V alloys is measured to be about 3000 s(-1). {332}< 113 > type mechanical twinning and stress induced omega phase transformation are dominant dynamic deformation modes of Ti-16V alloys. Schmid factor, calculated by the twinning Schmid factor model, is proved to be a key parameter determining the activation of twinning behavior of Ti-16V alloys.