Abstract: The solution argon gas quenching and aging treatment of TC4 titanium alloy were carried out by using a vacuum heat treatment furnace. Effect of argon gas quenching pressure on the microstructure and mechanical properties of the alloy was studied, and the fracture surface was analyzed. The results show that after solution treatment at 955 ℃ for 1 h and aging treatment at 550 ℃ for 5 h, the strength of the TC4 titanium alloy first increases and then decreases with the increase of argon gas quenching pressure, the elongation and percentage reduction of area gradually increase, the impact absorbed energy increases, and the hardness first increases and then decreases. The higher the volume fraction of β phase, the smaller the width of α phase and β phase, and the better the comprehensive mechanical properties of the alloy. The comprehensive mechanical properties of the alloy are optimal when the argon gas quenching pressure is 4 bar, with the tensile strength of 1043.3 MPa, the yield strength of 961.3 MPa, the elongation of 12.9%, the percentage reduction of area of 38.5%, the impact absorbed energy of 47.0 J, and the Rockwell hardness of 37.6 HRC.

Key words: TC4 titanium alloy, vacuum gas quenching, microstructure, mechanical properties