Abstract: Effect of hot working process on microstructure and mechanical properties of TC6 titanium alloy bars was studied. The results indicate that the ø160 and ø60 mm bars are composed of equiaxed α phase+transformed β including platelet α phase when the TC6 titanium alloy is hot worked within 50 ℃ below the β phase transformation point. Compared with the core, more equiaxed α grains are found and the number and size of the platelet α phase are smaller in the surface. Furthermore, the continuous and discontinuous grain boundary α along prior β grain boundary occurs in core of the ø60 mm bar produced by the first hot rolling while that isn't found in the ø25 mm bar deformed fully due to the secondary hot rolling. When annealed at 900 ℃, more primary α and most of equiaxed α grains occur, but the grain size distribution is uneven in the ø25 mm bar. The strength of the ø60 mm bar in the surface is greater than in the core, and the strength decreases greatly and elongation varies slightly with the annealing temperature increasing. The strength of the ø25 mm bar decreases and the elongation increases gradually when the annealing temperature increases from as-rolled to 800 ℃, while the strength increases and the elongation decreases gradually with the continuous increase of annealing temperature to 900 ℃.

Key words: TC6 titanium alloy, hot working process, microstructure, mechanical properties