Abstract:The impact of rolling temperature and the crystallographic orientation of α-colonies on the globularization behavior of lamellar α+β microstructure in Ti-6Al-4V alloy was investigated. Firstly, the lamellar structure was heavily rolled at 600, 700, 800 and 900 °C, respectively. Heavy rolling from temperatures of 600 to 900 °C resulted in an increased volume fraction and thickness of β lamellae, while the corresponding parameters for α lamellae decreased. Then, these rolled α+β lamellar microstructures were spheroidized into equiaxed grains upon subsequent annealing. The results demonstrate that the globularization fraction of the lamellar structures diminishes as the rolling temperature increases. Additionally, the globularization fraction for α-colonies with hard crystallographic orientations, such as á0001？//ND and á0001？//TD, is considerably lower compared to those with softer orientations, positioned at certain angles to ND, RD, and TD during annealing process. This results in heterogeneous globularization of α lamellae, leading to the development of pronounced sharp micro-texture. Furthermore, the slipping deformations of α-colonies with varying crystallographic orientations during rolling were meticulously analyzed.

Key words: heterogeneous globularization; Ti-6Al-4V alloy; lamellar structure; slip; orientation; misorientation