Extra-strengthening in a harmonic structure designed pure titanium due to preferential recrystallization phenomenon through thermomechanical treatment

The effect of thermomechanical processing (TMP), consisting of cold rolling followed by annealing, on the microstructure and mechanical properties of Harmonic Structure designed commercially pure Ti (HS–Ti) was studied. The TMP of HS-Ti led to the evolution of a peculiar preferentially recrystallized structure, localized in the Shell and Shell-Core interface regions. The underlying mechanism for such a unique microstructural evolution in the TMP HS-Ti has been proposed and discussed. The TMP treated HS-Ti specimens exhibited considerably higher strength values and comparable ductility with respect to its conventional homogeneous structured Ti (Homo-Ti) and as-sintered HS-Ti counterparts. The present work demonstrated that it is feasible to further enhance the superior mechanical properties of harmonic-structured materials through controlling the volume fraction and the grain size of the Core/Shell via controlling TMP parameters.