Adiabatic shear localization in pure titanium deformed by dynamic loading: Microstructure and microtexture characteristic

The adiabatic shear localization characteristic of annealed pure titanium was studied by means of hat-shaped specimen and Split Hopkinson Pressure Bar system. The microstructure and microtexture of the received shear localization regions were investigated by optical microscopy (OM), electron backscatter diffraction (EBSD) technique, transmission electron microscopy (TEM) and microhardness tests. The results show that microstructure within the adiabatic shear band consists of ultrafine grains with well defined high-angle-boundaries. In the vicinity of the shear band, grains are elongated toward the shear direction, and deformation twins including {10 (1) over bar2} <<(1)over bar>011> and {11 (2) over bar2} <11<(2)over bar>(3) over bar> are frequently observed. Microhardness tests reveal that the value of Vickers hardness in the shear band is the higher than all of the outside regions due to the strengthening effect of the ultrafine grains. Microtexture analysis reveals that a stable orientation, in which the <11<(2)over bar>0> direction tends to align with the local shear direction and the {10 (1) over bar0} plane tends to parallel to the local shear plane, develops in the shear localization region. The calculated results show that the dynamic recrystallization (DRX) can take place in the process of deformation on the basis of the rotational dynamic recrystallization mechanism. (C) 2015 Elsevier B.V. All rights reserved.