RELATIONSHIP BETWEEN TEXTURE AND GRAIN-BOUNDARY CHARACTER DISTRIBUTION IN RECRYSTALLIZED PURE TITANIUM

Orientation and grain boundary character distributions in recrystallized pure titanium with hcp structure were investigated by means of the Selected Area Channeling Pattern (SACP) method in order to understand the formation of a characteristic recrystallization texture in pure titanium. The samples uni-directionally rolled at room temperature with reduction of about 95% were annealed at 1073 K for 600 s and 7.2 ks in vacuum, respectively. Texture evolution was measured both with X-ray diffraction and with the SACP method which was developed quite recently by the present authors. By analyzing the SACPs orientation relationship between the adjacent grains was calculated and the grain boundary character was determined on the basis of the Coincidence Site Lattice model. The distribution of grain boundary disorientations was bimodal; i.e. two peaks at low (about 15°) and high (65-70°) disorientation. Moreover, there was a tendency that low angle boundaries form clusters and the orientation distribution is inhomogeneous in relation to microstructure. The fraction of coincidence boundaries about 〈101̄0〉 or 〈112̄O〉 was very low in the samples annealed for 600 s and 7.2 ks, while the Σ7 coincidence boundaries about the 〈0001〉 axis increased with annealing time.