Grain size-dependent tensile behaviour in a metastable beta titanium alloy

The present study investigates the effect of beta grain size on the stability of the beta phase in terms of trigger stress and the resultant mechanical properties of metastable beta titanium alloy. The trigger stress has a complex U-shaped relation concerning the beta grain size, which could be due to alternant mechanisms from interface friction and elastic energy. Nevertheless, the residual stress/strain could affect the trigger stress in the small grain size scale. More interestingly, dominant deformation modes are altered by a change of grain size with predominant stress-induced martensite (SIM) at small grain size and prime dislocation at large grain size, leading to grain size-dependent tensile behaviour of a metastable beta titanium alloy.