Influences of cold rolling deformation and annealing temperature on the microstructures and properties of pure titanium seamless tubes

Pure titanium tubes with different cold rolling deformations were annealed at different temperatures (450、470、490 ℃) to investigate the influences of deformations and annealing temperatures on the microstructures, texture evolution and mechanical properties of tubes. It is shown that the microstructure of the cold-rolled tubes with small deformation contains a great amount of twins, which mainly consist of {$ \text{11}\bar {\text{2}}\text{2} $}<$1 \text{1}\bar {\text{2}}\bar {\text{3}}\text{ > } $ compression twins and {$ \text{10}\bar {\text{1}}\text{2} $}$ \text{ < 10}\bar {\text{1}}\text{1 > }\text{} $tensile twins. The grains in the cold-rolled tubes with the greater deformation were severely deformed, along with the reduction of twins amount which is dominated by compression twins. The microstructure of tubes with the large deformation shows a strong texture of <$ \text{10}\bar {\text{1}}\text{0} $>//AD, and the other tube with small deformation shows a basal bimodal basal texture. The recrystallization proportion of the pure titanium tube, which is more severely deformed, increases gradually with the increase in annealing temperatures and its ratio reaches 50.5% after 490 ℃ annealing. Meanwhile, the tensile strength of the strongly deformed tubes decreases dramatically after 490 ℃ annealing, with the weakening of the cold-rolled texture and intensifying of the bimodal basal texture. The microstructural change of seamless tubes with the small deformation is not obvious, with a gentle reduction of the tensile strength, and the texture changes gradually from the bimodal basal texture to <$ \text{10}\bar {\text{1}}\text{0} $>//AD texture with the increase in annealing temperatures.