In situ EBSD investigation of microtexture evolution and slip activation of α macrozones during tensile deformation in Ti-6Al-4V alloy

The macrozone with sharp local texture is known as a potential cause of the reduced fatigue resistance and lifetime of titanium alloys . In this work, the microtexture evolution and slip activation of α macrozones during tensile deformation in Ti-6Al-4V alloy were analyzed by in situ EBSD . The results indicate that the α macrozones rotate with the orientation change under tensile deformation . The destruction of macrozones occurs when the c axis of the macrozone nearly overlaps with the stress direction. In such a case, the activation of the basal slip system is insufficient, which leads to severe stress concentration and local dislocation accumulation. Consequently, the α laths within the macrozone partially rotates to other directions for pyramidal < c + a > slip system activation. The large macrozone is thus segmented by the rotated α phase. In addition, a small rotation of the macrozone occurs when the angle between the tensile direction and the c -axis ( θ ) increases. In such a case, both basal and pyramidal < c + a > slip systems activate and contribute to the c -axis deformation. Thus, the deformation is homogeneous and the dislocation density is low within the macrozone. If only the pyramidal < c + a > slip system is activated, the macrozone nearly remains unchanged during deformation over a wide range of θ values. This work provides an available route to control macrozones in titanium alloys by pre-deformation.