High strength titanium alloys suffer from a limited combination of strength and ductility.Considering their microstructure,the coarse β grain is a detrimental factor.In the present study,the effects of hot deformation and annealing treatment on the β grain refinement of Ti-5Al-5Mo-5V-1Cr-1Fe (TC18) titanium alloy have been investigated by using electronic backscattered diffraction(EBSD) and transmission electric microscopy (TEM).Hot compression tests of TC18 alloy were performed between 1073 and 1223 K at strain rates of 0.01 and 0.10 s-1.Subsequent annealing treatments were conducted to investigate the effect of deformation microstructure on the recrystallization behavior of β grains.The results indicate that dynamic recovery (DRV) is the dominant restoration mechanism during hot deformation.Discontinuous dynamic recrystallization (dDRX) is significantly limited at a higher temperature in the β region,whereas continuous dynamic recrystallization (cDRX) of the β phase is observed at a higher strain rate in the (α + β) region.The final annealing microstructure is highly dependent on the deformation microstructure.Limited dDRX during hot deformation could not effectively refine the β grains.The refined and uniform β grains with an average grain size of 12 μm are achieved by combining hot deformation and subsequent annealing in the (α + β) region.This study provides a guide for the β grain refinement of high strength titanium alloys.