Deformation heterogeneity and its effect on recrystallization behavior in commercially pure titanium: Comparative study on initial microstructures

Abstract

Commercially pure titanium (CP–Ti) has seen major applications in medical and chemical equipment. However, improving its strength in its coarse-grained state is expected to extend its usage in structural applications. This study demonstrated that tailoring bimodal grain structures (in terms of grain size or shape) in CP-Ti offers a new way to enhance its mechanical properties. For this, an extensive effort was made to clarify the relationship between the initial microstructures and the deformation heterogeneities of a CP-Ti (Gr. 2). Samples with initially equiaxed (EQ), bimodal (BM), and lamellar (LM) microstructures were cold-rolled and subjected to annealing at different temperatures. The results showed that variations in initial grain orientation, size, and morphology result in different deformation heterogeneities during the plastic deformation, which in turn play an important role in determining the recrystallization kinetics during annealing as well as the resulting mechanical properties. The initial BM and EQ microstructures yielded better mechanical performances in both their initial and cold-rolled states than the initial LM microstructure. Furthermore, the initial BM microstructure exhibited the best strength–ductility combination in both their partially and fully recrystallized states.