Ti-v-zr-cr-al system ultra-high strength near-beta titanium alloy and preparation method thereof

Abstract

The application discloses a Ti-V-Zr-Cr-Al system ultrahigh-strength near-beta titanium alloy and a preparation method thereof, and belongs to the technical field of titanium alloy materials. The ultrahigh-strength near-beta titanium alloy contains 5.0-5.5% of Al, 11.0-11.5% of V, 2.5-3.0% of Cr, 4.5-5.0% of Zr, and the balance of Ti and inevitable impurity elements according to mass percentage. In the preparation process, firstly, the alloy ingot is subjected to open forging, and then is subjected to upsetting and drawing forging after being cooled to a phase transition point, so that a certain amount of primary alpha phase is formed in the alloy and is uniformly distributed in beta grains, thereby obtaining a titanium alloy forging blank; and then, the titanium alloy forging blank is sequentially subjected to solid solution treatment and aging treatment, thereby obtaining a near-beta ultrahigh-strength titanium alloy with a duplex structure. The titanium alloy has a tensile strength of more than 1800 MPa, a yield strength of 1780 MPa, a fracture elongation of more than 3.2%, and a uniform elongation of more than 2.8%. In particular, the tensile strength reaches 1800 MPa, and the titanium alloy can meet the requirements of the fields of aerospace, energy industry and the like, and has high use value and popularization value.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy materials technology, specifically to a Ti-V-Zr-Cr-Al system ultra-high strength near-β titanium alloy and its preparation method. Background Technology

[0002] Titanium and its alloys possess excellent comprehensive properties, including strength, modulus, toughness, high damage tolerance, corrosion resistance, and weldability, attracting widespread attention across various industries. Currently, high-strength titanium alloys are mainly β-titanium alloys, including some α+β two-phase alloys. Among them, β-titanium alloys have received widespread attention both domestically and internationally due to their high strength, good cold forming properties, and excellent strength-ductility balance, especially near-β and metastable β alloys, which combine the performance advantages of both α+β two-phase alloys and β alloys. Based on the Mo equivalent, β-type titanium alloys can be divided into four types: those with a Mo equivalent of 0 to 5 are called β-rich stabilizing element α+β-type titanium alloys; those with a Mo equivalent of 5 to 10 are called near-β-type titanium alloys; those with a Mo equivalent of 10 to 30 are called metastable β-type titanium alloys; and those with a Mo equivalent greater than 30 are called stable β-type titanium alloys.

[0003] For traditional high-strength β-titanium alloys such as Ti-1023, Ti-6554, Ti-5553, and Ti-55531, the yield strength after aging is generally around 1200–1300 MPa. Their forgings have been successfully applied to key components such as aircraft landing gear and connecting rods. Recently, some researchers have also developed various series of ultra-high-strength titanium alloys, such as the 1300 MPa grade Ti-Al-Mo-V-Cr-Zr system, the 1400 MPa grade Ti-Al-Mo-V-Cr-Fe system and Ti-Al-Mo-Fe system, the 1500 MPa grade Ti-Al-Mo-V-Cr-Zr-Fe-Nb-Sn system and Ti-Al-Mo-V-Cr-Zr-Nb system, and the 1600 MPa grade Ti-Al-Mo-V-Cr-Zr-Sn system.

[0004] However, with the rapid and leapfrog development of next-generation weapons and equipment such as hypersonic missiles, aircraft, unmanned combat aerial vehicles, highly stealthy and highly maneuverable strategic bombers, and new concept weapons, the development of ultra-high-strength titanium alloy materials to achieve superior comprehensive performance requirements such as higher strength, high toughness, damage tolerance, high fatigue performance, low cost, and weldability is urgently needed to meet the design and service goals of lightweight and long service life of next-generation weapons and equipment. Therefore, in order to cope with increasingly harsh operating environments and meet the requirements of future high-performance aircraft for ultra-high-strength structural titanium alloys, it is necessary to carry out research on new 1800MPa-grade ultra-high-strength titanium alloys. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a Ti-V-Zr-Cr-Al series ultra-high strength near-β titanium alloy and its preparation method, the strength of which reaches the 1800MPa level.

[0006] This invention is achieved through the following technical solution:

[0007] A Ti-V-Zr-Cr-Al series ultra-high strength near-β titanium alloy, comprising, by mass percentage, 5.0–5.5% Al, 11.0–11.5% V, 2.5–3.0% Cr, 4.5–5.0% Zr, with the balance being Ti and unavoidable impurity elements.

[0008] Preferably, the ultra-high strength near-β titanium alloy has a dual-state microstructure, including a primary α phase, a high-density distributed ultrafine secondary α phase, and a β phase.

[0009] Preferably, the diameter of the primary α phase is 0.75–0.85 μm; and the width of the ultrafine secondary α phase is 20–25 nm.

[0010] Preferably, the properties of the ultra-high strength near-β titanium alloy are as follows:

[0011] Tensile strength R m The strength ranges from 1818 to 1844 MPa, and the yield strength R is... 0.2 The strength is 1786–1801 MPa, and the elongation at break is A. f The elongation is 3.2% to 5.1%, with a uniform elongation A. u It ranges from 2.8% to 3.5%.

[0012] A method for preparing a Ti-V-Zr-Cr-Al system ultra-high strength near-β titanium alloy includes the following steps:

[0013] Step 1: Prepare alloy ingots;

[0014] Step 2: Forge the alloy ingot into a blank and then cool it to the phase transformation point for upsetting and drawing. A certain amount of primary α phase is formed in the alloy and evenly distributed in the β grains to obtain a titanium alloy forging blank.

[0015] Step 3: The titanium alloy forging billet is subjected to solution treatment and aging treatment in sequence to obtain a near-β ultra-high strength titanium alloy with a dual-state structure;

[0016] The methods for solution treatment and aging treatment are as follows:

[0017] The titanium alloy is heated to 10–30°C below the β-phase transformation temperature for solution treatment to form a metastable β-phase in the alloy; then it is aged in the temperature range of 470–490°C.

[0018] Preferably, the temperature for forging in step 2 is 1000℃~1100℃.

[0019] Preferably, the phase transition temperature is 790°C. 5℃.

[0020] Preferably, the solution treatment method involves heating the titanium alloy to 10–30°C below the β-phase transformation temperature for solution treatment, followed by water cooling to room temperature.

[0021] Preferably, the heat preservation time for the aging treatment is 4 hours.

[0022] Preferably, the alloy ingot is obtained by multiple melting processes in a vacuum consumable arc furnace.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] This invention provides a Ti-V-Zr-Cr-Al system of ultra-high strength near-β titanium alloy with a Mo equivalent of 6.7. Compared to existing high-strength titanium alloys, the absence of Mo, an alloying element with an extremely high melting point, helps reduce the difficulty of industrial titanium alloy smelting. Simultaneously, the β-phase stabilizing element V, by mass percentage, is not less than 11.0%. V has a higher solid solubility in the α-phase than Mo, and such a high V content can effectively strengthen the β-phase through solid solution, while also having a certain strengthening effect on the α-phase. It also lowers the c / a value of the α-phase, which is beneficial for α-phase slippage, giving the titanium alloy better α / β phase interfacial compatibility. The Al content, by mass percentage, ranges from 5.0% to 5.5%. Al promotes the precipitation of secondary α-phase and prevents the formation of ω-phase. Too low a content results in insignificant solid solution strengthening and may lead to a low phase transformation point, which is detrimental to hot deformation processes. Too high a content leads to an ordered trend, which is harmful to the fracture toughness of the TiAl intermetallic compound. Simultaneously, the addition of a higher content of the neutral element Zr further strengthens the α phase through solid solution, increasing the critical shear stress of dislocation slip within the α phase, thereby improving the overall strength of the alloy. A certain amount of the β phase stabilizing element Cr mainly plays a solid solution strengthening role in the β phase, improving the material's plasticity, toughness, and hardenability. At the same time, the fast-diffusing element Cr also facilitates the rapid precipitation and nucleation of the α phase, thus forming an ultrafine secondary α phase.

[0025] The near-β titanium alloy of this invention possesses outstanding mechanical properties. After solution treatment and aging, its tensile strength exceeds 1800 MPa, yield strength exceeds 1780 MPa, elongation at break exceeds 3.2%, and uniform elongation exceeds 2.8%. The microstructure of this near-β titanium alloy is a typical bimodal structure of high-strength titanium alloys, containing a small amount of primary α phase with a diameter of approximately 0.75–0.85 μm and a high-density distribution of ultrafine secondary α phase with a width of approximately 20–25 nm. By combining the plastic effect of the micron-sized primary α phase with the strengthening effect of the ultrafine nano-sized secondary α phase, the alloy's strength and plasticity can be improved simultaneously. This achieves a balance between maintaining a certain level of plasticity and ultra-high strength, providing a theoretical and material technology foundation for promoting the engineering application of ultra-high-strength titanium alloys, further developing my country's aerospace titanium alloy material system, and meeting future demands for ultra-high-strength titanium alloy materials. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The image shows the microstructure of the novel ultra-high strength near-β titanium alloy based on the Ti-V-Zr-Cr-Al system prepared in Example 1 of this invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0030] A Ti-V-Zr-Cr-Al series ultra-high strength near-β titanium alloy, comprising, by mass percentage, 5.0–5.5% Al, 11.0–11.5% V, 2.5–3.0% Cr, 4.5–5.0% Zr, with the balance being Ti and unavoidable impurity elements.

[0031] This Ti-V-Zr-Cr-Al series ultra-high strength near-β titanium alloy has a Mo equivalent of 6.7 and a phase transformation temperature of 790°C. 5℃. Compared to existing high-strength titanium alloys, the absence of Mo, an alloying element with an extremely high melting point, helps reduce the difficulty of industrial titanium alloy smelting. Simultaneously, the β-phase stabilizing element V, at a mass percentage of not less than 11.0%, can effectively strengthen the β-phase through solid solution, and also has a certain strengthening effect on the α-phase, while simultaneously reducing the c / a value of the α-phase, which is beneficial for dislocation slip in the α-phase. Adding higher amounts of the α-stabilizing or neutral elements Al and Zr further strengthens the α-phase through solid solution, increasing the critical shear stress for dislocation slip within the α-phase, thereby improving the overall strength of the alloy. A certain amount of the β-phase stabilizing element Cr mainly plays a solid solution strengthening role for the β-phase, while the fast-diffusion element Cr also promotes the rapid precipitation and nucleation of the α-phase, thus forming an ultrafine secondary α-phase.

[0032] This Ti-V-Zr-Cr-Al series ultra-high strength near-β titanium alloy is a near-β ultra-high strength titanium alloy with a dual-state microstructure. The properties of this titanium alloy are: tensile strength R... m The strength ranges from 1818 to 1844 MPa, and the yield strength R is... 0.2 The strength is 1786–1801 MPa, and the elongation at break is A. f The elongation is 3.2% to 5.1%, with a uniform elongation A. u It ranges from 2.8% to 3.5%.

[0033] Correspondingly, this application also provides a method for preparing a Ti-V-Zr-Cr-Al system ultra-high strength near-β titanium alloy, including the following steps:

[0034] Step 1: Prepare 5.0-5.5% Al, 11.0-11.5% V, 2.5-3.0% Cr, and 4.5-5.0% Zr by mass percentage. Mix the above raw materials evenly and then melt them to obtain alloy ingots.

[0035] Specifically, high-purity Al, high-purity V, electrolytic Cr, and sponge Zr and sponge Ti are mixed and pressed into electrodes according to the designed composition, and then melted into alloy ingots twice using a conventional vacuum consumable arc furnace.

[0036] Step 2: Forge the alloy ingot in the initial stage and cool it down to the phase transformation point for repeated upsetting and drawing to obtain a titanium alloy forging billet.

[0037] The alloy ingot is forged at a temperature of 1000℃~1100℃, and then the forging temperature is gradually reduced to around the phase transformation point of 790℃ for repeated upsetting and drawing forging to achieve static recovery and dynamic recrystallization of its microstructure. After final forging, a certain amount of primary α phase is uniformly distributed in fine β grains, resulting in an ultra-high strength titanium alloy forging billet.

[0038] Step 3: Perform solution treatment and aging treatment on the titanium alloy forging billet in sequence to obtain a near-β ultra-high strength titanium alloy with a dual-state structure.

[0039] Solution treatment: The titanium alloy is heated to 10-30°C below the β phase transformation temperature for solution treatment, and then cooled to room temperature, i.e., within the temperature range of 760-780°C, to form a metastable β phase. A small amount of primary α phase can suppress the excessive growth of β grains. Then, aging treatment is performed.

[0040] Aging treatment: High-temperature aging is carried out by holding at 470-490℃ for 4 hours to induce the dispersion precipitation of fine secondary α phase, thereby achieving precipitation strengthening and finally obtaining a near-β ultra-high strength titanium alloy with a dual-state structure.

[0041] This near-β titanium alloy, after solution treatment and aging, exhibits a typical bimodal microstructure, containing a small amount of primary α phase with a diameter of approximately 0.75–0.85 μm and a high-density distribution of ultrafine secondary α phase with a width of approximately 20–25 nm. Combining the plastic effect of the micron-sized primary α phase with the strengthening effect of the ultrafine nano-sized secondary α phase, it can simultaneously improve the alloy's strength and plasticity, resulting in extremely outstanding mechanical properties: tensile strength greater than 1800 MPa, yield strength greater than 1780 MPa, elongation at break greater than 3.2%, and uniform elongation greater than 2.8%. This near-β titanium alloy maintains a certain level of plasticity while possessing ultra-high strength, providing a theoretical and material technology foundation for promoting the engineering application of ultra-high-strength titanium alloys, further developing my country's aerospace titanium alloy material system, and meeting future demands for ultra-high-strength titanium alloy materials.

[0042] Example 1

[0043] A method for preparing a Ti-V-Zr-Cr-Al system ultra-high strength near-β titanium alloy includes the following steps:

[0044] Step 1: By mass percentage, mix Al 5.1%, V 11.3%, Cr 2.7%, Zr 4.7%, with the balance being Ti and unavoidable impurities, press them into electrodes, and then melt them twice in a vacuum arc furnace to form alloy ingots.

[0045] The above raw materials are high-purity Al, high-purity V, electrolytic Cr, and sponge Zr and sponge Ti.

[0046] Step 2: The alloy ingot is forged at 1050℃, and then the forging temperature is gradually reduced to around 790℃, the phase transformation point, for repeated upsetting and drawing forging to achieve static and dynamic recrystallization of its microstructure. After final forging, a certain amount of primary α phase is uniformly distributed in fine β grains to obtain an ultra-high strength titanium alloy forging billet.

[0047] Step 3: Perform solution treatment and aging treatment on the titanium alloy forging billet.

[0048] Solution treatment within the 770℃ temperature range forms a metastable β phase, and a small amount of primary α phase can suppress the excessive growth of β grains;

[0049] Then, high-temperature aging within the temperature range of 480℃ induces the dispersion precipitation of fine secondary α phase, thereby achieving precipitation strengthening and finally obtaining an ultra-high strength near-β titanium alloy.

[0050] The dual-state microstructure of this ultra-high strength near-β titanium alloy is as follows: Figure 1 As shown, the alloy in this embodiment contains a small amount of primary α phase with a diameter of about 0.79 μm and a high-density distribution of ultrafine secondary α phase with a width of about 21 nm, and the remainder is β phase.

[0051] The Ti-V-Zr-Cr-Al ultra-high strength near-β titanium alloy prepared in this embodiment was heat-treated and then subjected to room temperature tensile property testing according to the requirements of GB / T228.1-2010 standard. Its tensile properties are as follows: tensile strength R... m The yield strength is 1844 MPa, and the yield strength R is... 0.2 The strength is 1801 MPa, and the elongation at break is A. f The uniform elongation is 5.1%, A u The value is 3.5%, as shown in Table 1. This embodiment of the alloy maintains a certain level of plasticity while also possessing ultra-high strength.

[0052] Example 2

[0053] A method for preparing a Ti-V-Zr-Cr-Al system ultra-high strength near-β titanium alloy includes the following steps:

[0054] Step 1: By mass percentage, mix Al 5.5%, V 11.0%, Cr 2.5%, Zr 5.0%, with the balance being Ti and unavoidable impurities, press them into electrodes, and then melt them twice in a vacuum arc furnace to form alloy ingots.

[0055] The above raw materials are high-purity Al, high-purity V, electrolytic Cr, and sponge Zr and sponge Ti.

[0056] Step 2: The alloy ingot is forged at 1000℃, and then the forging temperature is gradually reduced to around 790℃, the phase transformation point, for repeated upsetting and drawing forging to achieve static and dynamic recrystallization of its microstructure. After final forging, a certain amount of primary α phase is uniformly distributed in fine β grains to obtain an ultra-high strength titanium alloy forging billet.

[0057] Step 3: Perform solution treatment and aging treatment on the titanium alloy forging billet.

[0058] Solution treatment: Solution treatment within the temperature range of 780℃ forms a metastable β phase, and a small amount of primary α phase can suppress the excessive growth of β grains;

[0059] Aging treatment: High-temperature aging within the temperature range of 470℃ induces the dispersion precipitation of fine secondary α phase, thereby achieving precipitation strengthening and finally obtaining ultra-high strength near-β titanium alloy.

[0060] The dual-state microstructure of this ultra-high strength near-β titanium alloy is as follows: Figure 1 As shown, the alloy in this embodiment contains a small amount of primary α phase with a diameter of about 0.85 μm and a high-density distribution of ultrafine secondary α phase with a width of about 20 nm, and the remainder is β phase.

[0061] The Ti-V-Zr-Cr-Al ultra-high strength near-β titanium alloy prepared in this embodiment was heat-treated and then subjected to room temperature tensile property testing according to the requirements of GB / T228.1-2010 standard. Its tensile properties are as follows: tensile strength R... m The yield strength is 1844 MPa, and the yield strength R is... 0.2 The strength is 1801 MPa, and the elongation at break is A. f The uniform elongation is 5.1%, A u The value is 3.5%, as shown in Table 1. This embodiment of the alloy maintains a certain level of plasticity while also possessing ultra-high strength.

[0062] Example 3

[0063] A method for preparing a Ti-V-Zr-Cr-Al system ultra-high strength near-β titanium alloy includes the following steps:

[0064] Step 1: By mass percentage, mix Al 5.0%, V 11.5%, Cr 3.0%, Zr 4.5%, with the balance being Ti and unavoidable impurities, press them into electrodes, and then melt them twice in a vacuum arc furnace to form alloy ingots.

[0065] The above raw materials are high-purity Al, high-purity V, electrolytic Cr, and sponge Zr and sponge Ti.

[0066] Step 2: The alloy ingot is forged at 1100℃, and then the forging temperature is gradually reduced to around 790℃, the phase transformation point, for repeated upsetting and drawing forging to achieve static and dynamic recrystallization of its microstructure. After final forging, a certain amount of primary α phase is uniformly distributed in fine β grains to obtain an ultra-high strength titanium alloy forging billet.

[0067] Step 3: Perform solution treatment and aging treatment on the titanium alloy forging billet.

[0068] Solution treatment: Solution treatment within the temperature range of 760℃ forms a metastable β phase, and a small amount of primary α phase can suppress the excessive growth of β grains;

[0069] Aging treatment: High-temperature aging within the temperature range of 490℃ induces the dispersion precipitation of fine secondary α phase, thereby achieving precipitation strengthening and ultimately obtaining an ultra-high strength near-β titanium alloy.

[0070] The dual-state microstructure of this ultra-high strength near-β titanium alloy is as follows: Figure 1 As shown, the alloy in this embodiment contains a small amount of primary α phase with a diameter of about 0.75 μm and a high-density distribution of ultrafine secondary α phase with a width of about 25 nm, and the remainder is β phase.

[0071] The Ti-V-Zr-Cr-Al ultra-high strength near-β titanium alloy prepared in this embodiment was heat-treated and then subjected to room temperature tensile property testing according to the requirements of GB / T228.1-2010 standard. Its tensile properties are as follows: tensile strength R... m The yield strength is 1818 MPa, and the yield strength R is... 0.2 The strength is 1786 MPa, and the elongation at break is A. f The uniform elongation is 3.2%, and the uniform elongation A is 3.2%. u The value is 2.8%, as shown in Table 1. This embodiment of the alloy maintains a certain level of plasticity while also possessing ultra-high strength.

[0072] Table 1. Performance test results of Ti-V-Zr-Cr-Al ultra-high strength near-β titanium alloys prepared in Examples 1-3

[0073]

[0074] As shown in Table 1, the embodiments of the present invention are novel ultra-high strength near-β titanium alloys with a dual-state microstructure, exhibiting a tensile strength exceeding 1800 MPa, a yield strength reaching 1780 MPa, a fracture elongation greater than 3.2%, and a uniform elongation greater than 2.8%. These results demonstrate that the novel ultra-high strength near-β titanium alloys of the present invention maintain a certain degree of plasticity while possessing ultra-high strength, particularly with a tensile strength reaching the 1800 MPa level. This presents significant value and broad prospects for the further application of near-β titanium alloys in aerospace, energy, and other fields requiring ultra-high strength performance in service.

[0075] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A Ti-V-Zr-Cr-Al series ultra-high strength near-β titanium alloy, characterized in that, By mass percentage, it includes 5.0–5.5% Al, 11.0–11.5% V, 2.5–3.0% Cr, 4.5–5.0% Zr, with the balance being Ti and unavoidable impurity elements; The properties of the ultra-high strength near-β titanium alloy are as follows: Tensile strength R m The strength ranges from 1818 to 1844 MPa, and the yield strength R is... 0.2 The strength is 1786–1801 MPa, and the elongation at break is A. f The elongation is 3.2% to 5.1%, with a uniform elongation A. u It ranges from 2.8% to 3.5%; The Ti-V-Zr-Cr-Al series ultra-high strength near-β titanium alloy is prepared by the following method, which includes the following steps: Step 1: Prepare alloy ingots; Step 2: The alloy ingot is forged at 1000℃~1100℃ and then cooled to the phase transformation point for upsetting and drawing forging. A certain amount of primary α phase is formed in the alloy and evenly distributed in the β grains to obtain titanium alloy forging billet. Step 3: The titanium alloy forging billet is subjected to solution treatment and aging treatment in sequence to obtain a near-β ultra-high strength titanium alloy with a dual-state structure; The methods for solution treatment and aging treatment are as follows: The titanium alloy is heated to 10–30°C below the β phase transformation temperature for solution treatment to form a metastable β phase in the alloy; then it is aged in the temperature range of 470–490°C, wherein the phase transformation temperature is 790±5°C.

2. The Ti-V-Zr-Cr-Al series ultra-high strength near-β titanium alloy according to claim 1, characterized in that, The ultra-high strength near-β titanium alloy has a dual-state microstructure, including a primary α phase, a high-density distributed ultrafine secondary α phase, and a β phase.

3. The Ti-V-Zr-Cr-Al series ultra-high strength near-β titanium alloy according to claim 2, characterized in that, The diameter of the primary α phase is 0.75–0.85 μm; the width of the ultrafine secondary α phase is 20–25 nm.

4. A method for preparing a Ti-V-Zr-Cr-Al system ultra-high strength near-β titanium alloy according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Prepare alloy ingots; Step 2: The alloy ingot is forged at 1000℃~1100℃ and then cooled to the phase transformation point for upsetting and drawing forging. A certain amount of primary α phase is formed in the alloy and evenly distributed in the β grains to obtain titanium alloy forging billet. Step 3: The titanium alloy forging billet is subjected to solution treatment and aging treatment in sequence to obtain a near-β ultra-high strength titanium alloy with a dual-state structure; The methods for solution treatment and aging treatment are as follows: The titanium alloy is heated to 10–30°C below the β phase transformation temperature for solution treatment to form a metastable β phase in the alloy; then it is aged in the temperature range of 470–490°C, wherein the phase transformation temperature is 790±5°C.

5. The method for preparing a Ti-V-Zr-Cr-Al system ultra-high strength near-β titanium alloy according to claim 4, characterized in that, The solution treatment method involves heating the titanium alloy to 10–30°C below the β-phase transformation temperature for solution treatment, followed by water cooling to room temperature.

6. The method for preparing a Ti-V-Zr-Cr-Al system ultra-high strength near-β titanium alloy according to claim 4, characterized in that, The heat preservation time for the aging treatment is 4 hours.

7. The method for preparing a Ti-V-Zr-Cr-Al system ultra-high strength near-β titanium alloy according to claim 4, characterized in that, The alloy ingot is obtained by multiple melting processes in a vacuum consumable arc furnace.

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