Abstract:The multi-pass thermal compression experiments of hot isostatic pressed TC4 titanium alloy were carried out on the Gleeble-1500D thermal simulator at strain rate of 0.001s-1~5s-1, the total deformation was 70%. The hot isostatic pressed TC4 titanium alloy was treated by 935℃+60 min+water quench solution treatment, and520℃+ 4/6h+water quench and 560+4/6h+water quench aging treatment, respectively. After multi-pass deformation, the samples were treated by solution treatment at 945℃ +60min+water quench and aging treatment at 560℃ +6h+water quench. The results show that the content of secondary α phase of hot isostatic pressed TC4 titanium alloy decreases with the increase of aging temperature, while the equiaxed α phase increases with the increase of aging time, and the microstructure mainly consists of secondary strip α phase and equiaxed α phase. Meanwhile, the ideal tri-modal microstructure(equiaxed α phase + secondary strip α phase + β transformation phase) of hot isostatic pressed TC4 titanium alloy can be obtained by solution and aging treatment during multi-pass deformation at the deformation temperature from 950℃ to 850℃and strain rate of 0.1s-1.