Effect of annealing temperature on microstructure and properties of Ti80 alloy extrusion tube

The effect of annealing process on microstructure and properties of Ti80 alloy extruded tube at 800-1 020℃was studied.The results show that the R_m of Ti80 tube increases from 910 MPa to 935 MPa when the annealing temperature rises from 800℃to 1 020℃,meanwhile the elongation increases from 15%to 17%and then goes down to 12%.Tensile strengh is nealy the same,but the ductility change is obvious.The annealing between 800℃and 900℃can remove the internal stress and creat the partial recrystallization.When the temperature goes up to 950℃,the recrystalization is sufficient,the microstructure is refined and spheroidized,and the mechanical properties of the tube are improved.When the annealing temperature continously goes up to 1 020℃,the microstructure changes to Widmanstaten structure and the ductility decreases.