High temperature tensile tests of hot-rolled annealing TC4 titanium alloy profile were carried out at 773 K

993 Kand 1 093 K

respectively with 1 mm/min

0.618 mm/min

0.382 mm/min and 0.236 mm/min.The microstructure of TC4 titanium alloy was observed by metallographic microscope

and the effects of different deformation temperature and strain rate on the microstructure evolution of TC4 titanium alloy were investigated.The results indicate that when the stretching rate is constant

the lamellarαphase in the microstructureis is firstly converted into the equiaxedαphase with the increase of deformation temperature.With the further increase of temperature

the grain boundary is broken

of which theαphase also began to undergo equiaxed transformation

and the microstructure is converted from weissmann microstructure to equiaxed microstructure.When the deformation temperature is constant

with decreasing in the stretching rate

the fineness and equiaxed degree of the laminar and grain boundaryαphases in the microstructure are increased

and the weissmann structure is converted to the equiaxed structure.