工程科学学报 (Jan 2022)
Effect of annealing time on microstructure and mechanical properties of Ti‒6.0Al‒3.0Zr‒0.5Sn‒1.0Mo‒1.5Nb‒1.0V titanium alloy
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.
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