Role of grain size in tensile behavior in twinning-induced plasticity β Ti-20V-2Nb-2Zr alloy

The role of grain size in tensile behavior in a metastable β Ti-20V-2Nb-2Zr mass % alloy was investigated. {332}〈113〉 mechanical twins are activated at high Schmid factors during tensile deformation and twinning becomes more difficult as the average grain size decreases. The dynamic Hall-Petch effect explains reasonably the decrease of the work hardening rate with decreasing grain size. The Hall-Petch equation applies when {332}〈113〉 twinning is dominant, and the Hall-Petch slope for {332}〈113〉 twinning is greater than that for dislocation gliding.