CN-117418140-B - High-strength alpha+beta titanium alloy suitable for 500 ℃ and preparation method thereof

Abstract

A high-strength alpha+beta titanium alloy suitable for 500 ℃ and a preparation method thereof comprise Ti, al, V, mo, nb, zr and other impurity elements, wherein the mass percent (wt%) of the alloy components is ,Al：6.2～7.2、V：1.5～2.5、Mo：1.5～2.5、Nb：0.5～1.5、Zr：13.5～14.5、Mn≤0.02、C≤0.02、Ni≤0.01、Si≤0.20、Sn≤0.20、Cr≤0.04、O≤0.02、P≤0.01、S≤0.01、N≤0.006、Ti： as follows. The invention realizes that the alloy has a specific structure morphology into a double-state structure through alloy design, consists of a primary alpha phase and a transition beta phase, wherein the content of the primary equiaxial alpha p phase is 10% -40%, the diameter is 7.0-9.0 mu m, the width of a secondary alpha s phase is 50-100 nm, alpha s can cause alpha s /β T interface formation for preventing dislocation movement, no harmful phase is generated after aging at 550 ℃, and the alloy has excellent heat stability and heat intensity. Meanwhile, the alloy has good mechanical property and excellent processing deformation capability, the room temperature yield strength exceeds 1250MPa, the room temperature tensile strength exceeds 1300MPa, the room temperature plasticity exceeds 7%, and the 500 ℃ tensile strength exceeds 600MPa, so that the alloy is a novel high-strength titanium alloy suitable for 500 ℃.

Inventors

• Kong Chuisen
• SONG MENGFAN
• DONG CHUANG
• WANG QING

Assignees

• 大连理工大学

Dates

Publication Date

20260508

Application Date

20231024

Claims (4)

1. 1. The titanium alloy suitable for 500 ℃ high-strength alpha+beta comprises a main alloy component Ti, al, V, mo, nb, zr and other impurity elements, wherein the mass percent (wt%) of the main alloy component is as follows, al is 6.2-7.2, V is 1.5-2.5, mo is 1.5-2.5, nb is 0.5-1.5, zr is 13.5-14.5, ti is the balance, the mass percent (wt%) of the other impurity elements is Mn less than or equal to 0.02, C less than or equal to 0.02, ni less than or equal to 0.01, si less than or equal to 0.20, sn less than or equal to 0.04, O less than or equal to 0.02, P less than or equal to 0.01, S less than or equal to 0.01 and N less than or equal to 0.006, the titanium alloy suitable for 500 ℃ high-strength alpha+beta titanium alloy has a dual-phase morphology by alloy design, is composed of a primary alpha p phase and a transition beta T phase, wherein the primary alpha phase is less than or equal to 5-5, the secondary alpha phase is equal to 5-35, the heat stability is 6250 nm, the residual heat stability is no less than or equal to 0.83 m equal to 0.35.50, and the thermal stability is equal to 0.83 m.
2. 2. The high strength alpha + beta titanium alloy suitable for use at 500C as recited in claim 1, wherein the high strength titanium alloy suitable for use at 500C has typical properties of room temperature yield strength >1250 MPa, room temperature tensile strength >1300 MPa, room temperature elongation > 7%, and high temperature tensile strength >600 MPa at 500C.
3. 3. A method for producing a high strength titanium alloy suitable for use at 500 ℃ as claimed in any one of claims 1 to 2, comprising the steps of: Firstly, weighing high-purity alloy materials according to mass percentage, respectively adding the high-purity alloy materials into a vacuum arc melting furnace from high to low according to the melting point of elements, and repeatedly melting for many times to obtain alloy ingots with uniform components; Secondly, heating the alloy ingot to the beta phase transition point temperature in a muffle furnace, preserving heat, and carrying out 5-10-pass unidirectional rolling on the alloy ingot after heat preservation treatment, wherein the deformation of single-pass rolling in multi-pass rolling treatment is 10% -15%, and the total pressing amount is 85% -90%; And thirdly, carrying out solution treatment for 1-1.5 h at 800-850 ℃, air-cooling to room temperature, carrying out aging treatment for 3-5 h at 530-560 ℃ and air-cooling to room temperature to obtain a final product.
4. 4. The method for preparing a high-strength titanium alloy at 500 ℃ according to claim 3, wherein in the second step, the heat preservation time is 25 min-35 min.

Description

High-strength alpha+beta titanium alloy suitable for 500 ℃ and preparation method thereof Technical Field The invention belongs to the technical field of new materials, and particularly relates to a 500 ℃ high-strength alpha+beta titanium alloy and a preparation method thereof, which can keep a two-state structure stable after aging at 550 ℃ and have high-temperature strength exceeding 600MPa at 500 ℃. Background Currently, alpha+beta high temperature titanium alloys generally work under the action of high temperature of 350-650 ℃ and complex stress, and the severe environment has strict requirements on various physical, chemical and mechanical properties of the alloy. The alpha+beta high temperature titanium alloy must have high heat resistance, good plasticity, high temperature oxidation resistance, corrosion resistance and long term tissue heat stability. With the rapid development of the aerospace industry, the thrust-weight ratio of the aircraft is increased, the working temperature of engine parts is continuously increased, and the research and the application of alpha+beta high-temperature titanium alloy for key parts such as a compressor disc, a blade, a wheel disc and the like are promoted. In order to improve the service performance of the alloy and meet the high-temperature strength requirement, a large amount of alpha stable elements (Al), beta stable elements (Mo, nb, V) and neutral elements (Zr) are added into the alpha+beta high-temperature titanium alloy for high-performance compressor disks, blades and wheel disks. However, the high alloying degree increases the difficulty of alloy processing deformation and structure property regulation, and meanwhile, if excessive addition of elements such as Al, zr and the like can cause the generation of precipitated phases, the strength and plasticity of the alloy are reduced, so that the application range of the alloy is greatly reduced. The room-temperature tensile strength of the alpha+beta high-temperature titanium alloy material for key components such as the existing compressor disc, blade, wheel disc and the like is difficult to break through 1300MPa, and meanwhile, the high-temperature tensile strength of the alpha+beta high-temperature titanium alloy material is difficult to be higher than 600MPa at 500 ℃. For example, the Ti-6Al-4V alloy originally developed in 1954 by the United states was one of the most widely used alpha+beta titanium alloys, operable at 350 ℃. Then, beta isomorphic elements Mo and Nb, neutral elements Zr and beta eutectoid element Si are added into the biphase alloy in each country to improve the high-temperature performance of the alloy, the BT9 alloy (Ti-6.5 Al-1.5Zr-3.5Mo-0.3Si, chinese denominated as TC 11) which is suitable for 500 ℃ and developed in 1958 in Russia, and the Ti-6Al-3Mo-2Sn-2Zr-2Nb-1.5Cr-0.1Si alloy (TC 21) developed by northwest nonferrous metal institute in 1977 can be used for a long time at 500 ℃. It can be seen that reasonable composition design has important significance to material properties. Furthermore, the morphology of the dual phase titanium alloy structure has a significant impact on material properties, especially the bimodal structure is known to provide a good balance between high strength and ductility, as well as good creep and fatigue resistance properties, from equiaxed primary alpha (alpha p) particles and beta transus (beta T). The elongation of Ti-6Al-4V titanium alloy prepared by LSF process was reported to be 18% higher than that of the wrought sample when it was solutionized at 920℃for 2h and at 550℃for 4 h. Triple heat treatment of Ti-6Al-4V-ELI titanium alloy prepared by LSF shows that the microstructure consists of lamellar structure composed of equiaxed alpha p and fine alpha s and residual beta phase, so that the elongation of the sample is greatly improved. Studies have shown that Ti-6Al-2Mo-2Cr alloys with equiaxed structure have lower strength than lamellar structure, but opposite ductility. In addition, different cooling modes have larger difference on mechanical properties of the alloy, mechanical property tests are respectively carried out on the TC21 alloy after air cooling and furnace cooling, and the TC21 alloy after air cooling has better yield strength and tensile strength than those after furnace cooling, and the ductility is just opposite. It can be seen that accurate tissue regulation has important significance to material properties. The existing alpha+beta high-temperature titanium alloy has the defects of simple preparation process, low cost, large deformation difficulty, poor tissue uniformity, insufficient temperature bearing capacity and difficult improvement of comprehensive performance. Therefore, two core problems restricting the development of the current alpha+beta high temperature titanium alloy are that, on one hand, the high temperature bearing capacity and the high temperature structure stability of the alloy are ensured, and meanwhile, the r