Abstract:
The effect of annealing time on the microstructure and mechanical properties of Ti‒6.0Al‒3.0Zr‒0.5Sn‒1.0Mo‒1.5Nb‒1.0V new titanium alloys were studied based on the optimum annealing temperature of 740 ℃. Results show that after smelting thrice by vacuum consumable arc furnace and thrice hot rolling processes, the microstructure of the sheet is the partial recrystallization structure composed of the primary α phase, structure of β transformation, and the processing status structure. With increased annealing time, the microstructure of the annealed sheet is mainly composed of the primary α phase, with the proportion of the α phase being gradually increased from 81.73% to 85.61%. The strip-shaped α phase in the microstructure is broken and spheroidized gradually, and an equiaxial α phase begins to be homogenized and coarsened. With the increase of annealing time, the elongation of annealed sheets increases greatly; the tensile strength initially decreases, increases, and then decreases again; and the yield strength and the microhardness first increase and then decrease. When the annealing time is 1 h, the fracture of the sheet has a ductile fracture mode and is composed of slip bands, ripple appearance, and small equiaxial dimples. When the annealing time is more than or equal to 2 h, the fracture exhibits a ductile fracture mode and is completely composed of equiaxial dimples. The optimal annealing process is achieved at 740 ℃ for 2 h, in which the tensile strength, yield strength, elongation, and microhardness of the alloy plate is 984 MPa, 941 MPa, 15.27%, and HV 347.67, respectively. The main results from this paper can guide the formulation of the annealing process of high-strength corrosion-resistant titanium alloy and provide a scientific basis for solving problems encountered in the actual production of titanium alloy.