退火时间对Ti‒6.0Al‒3.0Zr‒0.5Sn‒1.0Mo‒1.5Nb‒1.0V钛合金组织及力学性能的影响

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

  • 摘要: 针对近α型Ti‒6.0Al‒3.0Zr‒0.5Sn‒1.0Mo‒1.5Nb‒1.0V新型钛合金,在退火温度740 ℃的基础上,研究了退火时间对其组织与力学性能的影响。结果表明:经过3次真空自耗电弧炉熔炼,三火热轧后得到的板材组织由初生α相基体及β转变组织组成的部分再结晶组织和加工态组织等组成。随着退火时间的增加,退火板材的显微组织均以初生α相为主,且α相所占的比例从81.73%逐渐增加至85.61%,组织中长条状α相逐渐破碎球化,等轴α相开始均匀化、粗化。随着退火时间的增加,退火板材的延伸率逐渐增加,抗拉强度先降低再增加然后又降低,屈服强度先增加后降低,显微硬度先增加后降低。退火时间为1 h时,板材的断口由滑移带、涟波、小等轴韧窝组成,断裂方式为韧性断裂,退火时间大于等于2 h时,板材的断口完全由等轴韧窝组成,断裂方式为韧性断裂。最佳退火工艺为740 ℃退火2 h,此时板材的抗拉强度、屈服强度、延伸率和显微硬度分别为:984 MPa、941 MPa、15.27%、HV 347.67。研究结果对高强耐蚀钛合金退火工艺的制定有指导作用,为解决钛合金在实际生产中遇到的问题提供了科学依据。

     

    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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