1500MPa-grade titanium alloy bar and preparation method thereof

Abstract

The invention discloses a 1500MPa-grade titanium alloy bar and a preparation method thereof, and belongs to the field of titanium alloy preparation. The 1500MPa-grade titanium alloy bar comprises the following chemical components in percentage by mass: 5.5 to 6.5 percent of V, 4.5 to 5.5 percent of Mo, 3.0 to 4.0 percent of Al, 2.5 to 3.5 percent of Zr, 1.5 to 2.5 percent of Cr, 1.5 to 2.5 percent of Nb, 0.9 to 1.1 percent of Fe and the balance of Ti and impurities. The preparation method comprises the following steps: preparing raw materials according to the components, pressing the raw materials into electrode blocks, welding to obtain consumable electrodes, and performing multi-vacuum consumable smelting to obtain cast ingots; the cast ingot is subjected to cogging forging in a beta area, multi-heating-number upsetting and drawing deformation in the beta area and forged into a bar in a two-phase area; and through multi-pass rolling and multiple solid solution aging heat treatment, the 1500MPa-grade titanium alloy bar is obtained, meanwhile, the ductility is kept to be 6% or above, and the requirement of future aerospace for high-performance titanium alloy is met.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy preparation, and relates to a 1500MPa grade titanium alloy bar and its preparation method. Background Technology

[0002] Titanium alloys, due to their high specific strength, excellent corrosion resistance, and good high-temperature performance, have a wide range of applications in aerospace and other fields. Currently, the tensile strength of titanium alloy bars ranges from 1000 to 1200 MPa, and their fracture toughness is around 40 MPa.m. 1 / 2 ~60MPa.m 1 / 2 With the development of my country's aerospace industry, the performance requirements for titanium alloys in new aircraft and spacecraft are becoming increasingly stringent. Higher demands are being placed on the mechanical properties of titanium alloys, and ultra-high-strength titanium alloys with tensile strength of 1200-1500 MPa and shear strength ≥750 MPa are one of the future development trends. Currently, to achieve the 1500 MPa strength target, domestic and international efforts are mainly focused on developing near-β-type or metastable β-type titanium alloy systems, achieved through the addition of various β-stabilizing elements combined with complex heat treatment.

[0003] CN118028656A discloses an ultra-high strength and high plasticity Ti-Al-Mo-Zr-Sn-Cr-Fe titanium alloy and its preparation method. This method requires the addition of expensive Sn elements in the composition design, leading to a significant increase in raw material costs and smelting control costs. Therefore, it is more suitable for specific scenarios with extreme plasticity requirements, rather than general-purpose high-strength structural components. CN117107113A discloses a Ti-Al-V-Mo-Cr-Zr-Nb metastable β titanium alloy and its preparation method. This preparation method requires repeated upsetting and forging, resulting in a long process flow, high process complexity and manufacturing costs, and significant difficulty in controlling the stability of its microstructure and properties. CN119464838A discloses a 1500MPa grade ultra-high strength titanium alloy fastener, which achieves high strength by adding a high amount of Cr, but this significantly increases the alloy's density and may worsen its hot workability. This composition is designed for tensile bolts, shear bolts, and long threaded bolts, and is not suitable for large-sized products such as bars and forgings that require good forging formability. CN119506659A discloses a 1500MPa grade titanium alloy plate, but its composition has a wide range of Fe content, making it difficult to guarantee the stability and consistency of its microstructure and properties. Furthermore, its process mainly targets plate rolling and does not involve forging and rolling of bars.

[0004] Therefore, developing a titanium alloy bar with reasonable composition design, relatively simple process and easy industrial production, which can simultaneously possess ultra-high strength and good plasticity, and its preparation method, to meet the growing demand for high-performance titanium alloys in aerospace and other fields, is an urgent technical problem to be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the production cost of existing methods for preparing ultra-high strength titanium alloys is relatively high.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows: In a first aspect, the present invention provides a method for preparing 1500MPa grade titanium alloy rods, comprising the following steps: S1. Select raw materials based on the chemical composition of 1500MPa grade titanium alloy bars, then weigh and batch them; The chemical composition, by mass percentage, is: V 5.5~6.5%, Mo 4.5~5.5%, Al 3.0~4.0%, Zr 2.5~3.5%, Cr 1.5~2.5%, Nb 1.5~2.5%, Fe 0.9~1.1%, with the balance being Ti and unavoidable impurities; S2. The raw materials are pressed into electrode blocks, welded to obtain consumable electrodes, and subjected to three vacuum consumable melting processes to obtain titanium alloy ingots. S3. Titanium alloy ingots are processed into bars through β-zone forging, β-zone multi-pass upsetting and drawing, two-phase zone forging, and multi-pass rolling. S4. The bar is subjected to multiple solution aging heat treatments to obtain 1500MPa grade titanium alloy bar. The multiple solution aging heat treatment is as follows: solution treatment is performed at 830℃~920℃ for 1~3 hours; then the converter is cooled to 200℃ at 640℃~730℃, and then air-cooled to room temperature; finally, aging treatment is performed at 520℃~620℃ for 5~8 hours, and then air-cooled to room temperature.

[0007] In step S1 above, the impurity elements in the chemical composition of the 1500MPa grade titanium alloy bar are O<0.1%, N<0.01%, H<0.005%, and C<0.01%.

[0008] In step S1 above, the raw materials include sponge titanium, aluminum briquettes, sponge zirconium, Al-60Cr, Ti-50Nb, Ti-32Mo, Al-85V, and Ti-30Fe.

[0009] In step S2 above, the three vacuum self-consumption melting processes all employ a sinusoidal AC arc-stabilizing current. The specific process is as follows: First time: vacuum degree ≤2Pa, arc ignition to stable melting time ≤30min, average melting rate ≤5kg / min; Second and third times: vacuum degree ≤1.5Pa, arc ignition to stable melting time ≤25min, average melting rate ≤4kg / min.

[0010] In step S3 above, the temperature of the β-zone forging is 1000℃~1200℃.

[0011] In step S3 above, the upsetting and drawing in the β region is performed in 2 to 4 passes, and the deformation temperature of each pass decreases gradually within the range of 900℃ to 1100℃, with the temperature decrease between adjacent passes being 50℃ to 100℃.

[0012] In step S3 above, the forging temperature of the two-phase region is 800℃~950℃. First, it is forged into a square shape at 900℃≤T≤950℃, and then forged into a bar at 800℃≤T<900℃.

[0013] In step S3 above, the multi-pass rolling process specifically includes: the first pass rolling temperature is 900℃~920℃, and the deformation is 7%~10%; the second and third passes rolling temperature is 840℃~860℃, and the deformation is 18%~25%; the fourth and fifth passes rolling temperature is 810℃~830℃, and the deformation is 16%~20%.

[0014] Secondly, the present invention provides a 1500MPa grade titanium alloy rod prepared by the above-described preparation method, the chemical composition of which, by mass percentage, is: V 5.5~6.5%, Mo 4.5~5.5%, Al 3.0~4.0%, Zr 2.5~3.5%, Cr 1.5~2.5%, Nb 1.5~2.5%, Fe 0.9~1.1%, with the balance being Ti and unavoidable impurities, wherein the impurity elements are controlled to be O < 0.1%, N < 0.01%, H < 0.005%, and C < 0.01%.

[0015] Furthermore, the tensile strength of the aforementioned 1500MPa grade titanium alloy bar is >1500MPa, and the elongation is >6%.

[0016] The beneficial effects of this invention are as follows: This invention provides a set of efficient, stable, and potentially cost-effective methods for industrial production of high-performance titanium alloy bars. Based on the idea that the Gibbs free energies of the α phase and β phase are similar, a novel ultra-high-strength titanium alloy is designed. A forging + rolling processing technology is formulated to refine the grains of the titanium alloy matrix and generate a large number of defect densities. Through multiple solid solution aging heat treatments, the α phases of different morphologies and sizes in the titanium alloy are precipitated in stages, producing a 1500MPa grade titanium alloy bar while maintaining an elongation of over 6%, meeting the future aerospace requirements for high-performance titanium alloys. Detailed Implementation

[0017] To make the technical problems, solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with the embodiments. Unless otherwise defined, all technical terms used herein have the same meaning as understood by one of ordinary skill in the art.

[0018] This invention relates to a method for preparing 1500MPa grade titanium alloy rods, the specific steps of which include: Step 1: Alloy Composition Design. Based on the phase equilibrium of the α and β phases near the intersection of their Gibbs free energy curves in titanium alloys, the β phase can provide a driving force for the precipitation of the α phase, promoting the dispersion and precipitation of the α phase from the β matrix in a shorter time, thereby improving the overall mechanical properties of the alloy. Based on this principle, the following alloy composition (by mass percentage) was designed in this invention: V 5.5~6.5%, Mo 4.5~5.5%, Al 3.0~4.0%, Zr 2.5~3.5%, Cr 1.5~2.5%, Nb 1.5~2.5%, Fe 0.9~1.1%, with the balance being Ti and unavoidable impurities, wherein the impurity elements are controlled as follows: O < 0.1%, N < 0.01%, H < 0.005%, C < 0.01%.

[0019] The composition system of this invention effectively suppresses the transformation from the β phase to the α phase through the composite addition of multiple β-stabilizing elements, ensuring sufficient β-phase region for hot working and laying the foundation for obtaining fine and uniformly distributed α-precipitates in subsequent aging treatment. The precise proportions of each element ensure β-phase stability while mitigating macroscopic segregation and optimizing material density. In particular, Fe, as a strong β-stabilizing element, can significantly improve hardenability and aging strengthening effects, but Fe is prone to segregation. Therefore, this invention strictly controls the Fe content within the range of 0.9% to 1.1%, fully leveraging its strengthening effect while effectively suppressing the risk of segregation, ensuring the uniformity of the microstructure and the stability of its properties.

[0020] Step 2: Based on the titanium alloy composition designed in Step 1, select sponge titanium, aluminum briquettes, sponge zirconium, Al-60Cr, Ti-50Nb, Ti-32Mo, Al-85V, and Ti-30Fe as raw materials, then weigh, batch, press into electrode blocks, and weld to obtain consumable electrodes.

[0021] In one embodiment of the present invention, the sponge titanium is grade 0A, the purity of the aluminum granules is ≥99.5%, the purity of the sponge zirconium is ≥99.9%, the purity of Al-60Cr is ≥99.9%, the purity of Ti-50Nb is ≥99.8%, the purity of Ti-32Mo is ≥99.8%, the purity of Al-85V is ≥99.8%, and the purity of Ti-30Fe is ≥99.8%.

[0022] Step 3: The consumable electrode from Step 2 is subjected to three vacuum consumable melting processes to obtain a titanium alloy ingot. This invention ensures the compositional uniformity of the titanium alloy ingot through three vacuum consumable melting processes. Specifically, each of the three vacuum consumable melting processes uses a sinusoidal AC stabilizing current. Specifically, the vacuum degree of the first vacuum consumable melting process is controlled to be ≤2 Pa, the arc initiation to stable melting time is ≤30 min, and the average melting rate is ≤5 kg / min; the vacuum degree of the second and third vacuum consumable melting processes is controlled to be ≤1.5 Pa, the arc initiation to stable melting time is ≤25 min, and the average melting rate is ≤4 kg / min.

[0023] Step 4: The titanium alloy ingot from Step 3 is forged in the β region at a temperature of 1000℃~1200℃ to break up the coarse cast grains and lay the foundation for subsequent processing.

[0024] Step 5: After blanking, the β-region undergoes multiple upsetting and drawing processes to further refine the β-grains, fully break down and homogenize the microstructure. These multiple upsetting and drawing processes in the β-region consist of 2 to 4 passes. To avoid abnormal growth of the β-grains, the deformation temperature of each pass is gradually reduced within the range of 900℃ to 1100℃, with a temperature reduction of 50℃ to 100℃ between adjacent passes. This gradual cooling allows for continued deformation and refinement before the grains grow larger, resulting in a finer and more uniform β-transformation microstructure.

[0025] In one embodiment of the present invention, two-stage upsetting deformation is performed in the β region, with the first upsetting at 1000°C and the second upsetting at 950°C.

[0026] In one embodiment of the present invention, three-stage upsetting deformation is performed in the β region, with the first upsetting at 1100°C, the second upsetting at 1000°C, and the third upsetting at 900°C.

[0027] In one embodiment of the present invention, four-stage upsetting deformation is performed in the β region, with the first stage of upsetting at 1050°C, the second stage at 1000°C, the third stage at 950°C, and the fourth stage at 900°C.

[0028] Step Six: After upsetting, the material is forged into bars in the two-phase region at a temperature of 800℃~950℃. Forging thoroughly breaks down coarse grains, and simultaneously utilizes the principle of phase transformation recrystallization to distribute fine equiaxed α-phase particles on the matrix. Specifically, the two-phase region forging first involves forging into a square shape at 900℃≤T≤950℃, and then forging the square shape into bars at 800℃≤T<900℃.

[0029] Step 7: Roll the bar from Step 6 in multiple passes. The first pass is rolled at 900℃~920℃ with a deformation of 7%~10%, allowing the bar to heat up evenly and adapt to deformation. The second and third passes are rolled at 840℃~860℃ with a deformation of 18%~25%, performing significant deformation to further refine the grains. The fourth and fifth passes are rolled at 810℃~830℃ with a deformation of 16%~20%, performing greater deformation at lower temperatures to introduce more dislocations and deformation energy storage, providing more nucleation sites for subsequent solution aging treatment, resulting in finer and more dispersed α-phase precipitates.

[0030] Step 8: Perform multiple solution aging heat treatments on the bars from Step 7. Solution treatment is performed at 830℃~920℃ for 1~3 hours to partially dissolve the primary α phase, resulting in a supersaturated β phase matrix. The solution is then transferred to a furnace and cooled to 200℃ in the furnace. Afterward, it is removed and cooled to room temperature in air. Slow furnace cooling avoids internal stress and deformation caused by water quenching, while simultaneously allowing some fine, secondary α phases to precipitate from the β phase. Aging treatment is then performed at 520℃~620℃ for 5~8 hours, followed by air cooling to room temperature. Holding at an even lower temperature further allows the remaining supersaturated β phase to precipitate even finer aged α phases. This invention, through multiple solution aging heat treatments, controls the graded precipitation of α phases of different morphologies and sizes in titanium alloys, achieving a suitable match between the tensile strength and toughness of the titanium alloy. The fine α phases strongly hinder dislocation movement, achieving ultra-high strength, while the larger α phases ensure good plasticity and toughness.

[0031] The following specific embodiments will be provided to explain the solution of the present invention. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0032] The chemical composition (by mass percentage) and raw materials of the titanium alloy described in this embodiment of the invention are as follows.

[0033] Example 1: V 6.0%, Mo 4.7%, Al 3.4%, Zr 2.8%, Cr 1.9%, Nb 1.8%, Fe 1.0%, with the balance being Ti and unavoidable impurities, wherein the impurity elements are controlled to be O < 0.1%, N < 0.01%, H < 0.005%, and C < 0.01%.

[0034] Example 2: V 6.5%, Mo 5.5%, Al 4.0%, Zr 2.5%, Cr 2.0%, Nb 2.0%, Fe 1.0%, with the balance being Ti and unavoidable impurities, wherein the impurity elements are controlled to be O < 0.1%, N < 0.01%, H < 0.005%, and C < 0.01%.

[0035] Raw materials for preparation: 0A grade sponge titanium, aluminum briquettes with a purity of 99.5%, sponge zirconium with a purity of 99.9%, Al-60Cr with a purity of 99.9%, Ti-50Nb with a purity of 99.8%, Ti-32Mo with a purity of 99.8%, Al-85V with a purity of 99.8%, and Ti-30Fe with a purity of 99.8%.

[0036] Example 1: Preparation of 1500MPa grade titanium alloy rods, the specific steps are as follows.

[0037] (1) Based on the chemical composition of the titanium alloy, select the raw materials, weigh them, mix them, press them into 12 electrodes (12kg each), and weld them to obtain consumable electrodes.

[0038] (2) The consumable electrode was subjected to vacuum consumable melting. The vacuum degree was controlled at 1.3 Pa for the first melting, the arc ignition melting time was 10 min, and the average melting rate was 3 kg / min. The vacuum degree was controlled at 1.0 Pa for the second melting, the arc ignition melting time was 8 min, and the average melting rate was 2.5 kg / min. The vacuum degree was controlled at 0.9 Pa for the third melting, the arc ignition melting time was 8 min, and the average melting rate was 2 kg / min. The sinusoidal AC arc stabilizing current was used for all three vacuum consumable melting processes to obtain a titanium alloy ingot with a diameter of Φ310 mm.

[0039] (3) The titanium alloy ingot is forged at 1100℃, then forged at 1000℃ for the first upsetting and drawing, then forged at 950℃ for the second upsetting and drawing, then forged at 900℃ into a square shape, and finally forged at 850℃ into a Φ70mm bar.

[0040] (4) The bar is rolled in multiple passes. The first pass is rolled at 920°C with a deformation of 8%; the second and third passes are rolled at 860°C with a deformation of 20%; and the fourth and fifth passes are rolled at 810°C with a deformation of 18%.

[0041] (5) The bar was subjected to multiple solution aging heat treatments. First, solution treatment was performed at a temperature of 910℃ for 2 hours. Then, the temperature was changed to 700℃ and cooled to 200℃ in the furnace. The bar was then removed and cooled to room temperature in the air. Finally, aging treatment was performed at a temperature of 600℃ for 7 hours and air-cooled to room temperature to obtain titanium alloy bar. The tensile strength was 1520MPa and the elongation was 6.4%.

[0042] Example 2: Preparation of 1500MPa grade titanium alloy rods, the specific steps are as follows.

[0043] (1) Based on the chemical composition of the titanium alloy, select the raw materials, weigh them, mix them, press them into 50 electrodes (61kg each), and weld them to obtain consumable electrodes.

[0044] (2) The consumable electrode was subjected to vacuum consumable melting. The vacuum degree was controlled at 1.3 Pa for the first melting, the arc ignition melting time was 10 min, and the average melting rate was 3 kg / min. The vacuum degree was controlled at 1.0 Pa for the second melting, the arc ignition melting time was 8 min, and the average melting rate was 2.5 kg / min. The vacuum degree was controlled at 0.9 Pa for the third melting, the arc ignition melting time was 8 min, and the average melting rate was 2 kg / min. The sinusoidal AC stable arc current was used for all three vacuum consumable melting processes to obtain a titanium alloy ingot with a diameter of Φ750 mm.

[0045] (3) The titanium alloy ingot is forged at 1200℃, then forged at 1100℃ for the first upsetting and drawing, at 1000℃ for the second upsetting and drawing, at 950℃ for the third upsetting and drawing, then forged into a square at 900℃ and into a bar at 850℃.

[0046] (4) The bar is rolled in multiple passes. The first pass is rolled at 900°C with a deformation of 7%; the second and third passes are rolled at 850°C with a deformation of 25%; and the fourth and fifth passes are rolled at 820°C with a deformation of 20%.

[0047] (5) The bar was subjected to multiple solution aging heat treatments. First, solution treatment was performed at a temperature of 880℃ for 3 hours. Then, the temperature was reduced to 680℃ in a converter and cooled to 200℃ in the furnace. The bar was then removed and cooled to room temperature in the air. Finally, aging treatment was performed at a temperature of 580℃ for 8 hours and then cooled to room temperature in the air to obtain titanium alloy bars. The tensile strength was 1580MPa and the elongation was 6.8%.

[0048] Comparative Example 1: Titanium alloy bars were prepared according to the chemical composition and process parameters described in Example 2. The only difference from Example 2 was that in step (3), the titanium alloy ingot was forged at 1100°C, the first upsetting and drawing was performed at 1100°C, the ingot was forged into a square shape at 900°C, and the ingot was forged into a Φ70mm bar at 850°C. The titanium alloy bars were prepared and their tensile strength was tested to be 1420MPa and the elongation was 5.7%.

[0049] A comparison of Example 2 and Comparative Example 1 shows that the ingot obtained by vacuum arc remelting may have coarse columnar crystals and dendritic segregation. Comparative Example 1, however, only underwent a single upsetting and drawing process, resulting in insufficient deformation and strain accumulation to break up the original as-cast structure. Recrystallization was inadequate, and the diffusion and homogenization of alloying elements were not promoted. This leads to uneven element distribution and coarse grain size within the microscopic region. The residual coarse grains and segregation result in reduced overall strength and make the ingot more susceptible to cracking under stress, leading to decreased plasticity.

[0050] Comparative Example 2: Titanium alloy rods were prepared according to the chemical composition and process parameters described in Example 2. The only difference from Example 2 was that in step (5), a solution treatment was first performed at a temperature of 880°C for 2 hours; then the rods were taken out and cooled to room temperature in air; finally, an aging treatment was performed at a temperature of 580°C for 8 hours, followed by air cooling to room temperature; titanium alloy rods were obtained, and their tensile strength was tested to be 1340 MPa and their elongation to be 4.8%.

[0051] A comparison of Example 2 and Comparative Example 2 shows that Comparative Example 2 did not undergo "converter cooling" after solution treatment, but was directly air-cooled. This resulted in the supersaturated β phase failing to pre-precipitate during the cooling process, thus failing to form a fine, dispersed secondary α phase. Under the same subsequent aging conditions, the α phase mainly nucleated non-uniformly from defects such as grain boundaries, resulting in a low nucleation rate, coarsened precipitate size, and sparse distribution, leading to a decrease in tensile strength. At the same time, the non-uniform precipitate phase easily caused stress concentration, forming microcracks and drastically deteriorating plasticity.

[0052] In summary, the 1500MPa grade titanium alloy bar of the present invention achieves both high strength and good plasticity through the synergistic effect of composition design and process. The resulting titanium alloy bar has a tensile strength exceeding 1500MPa and an elongation greater than 6%, meeting the application requirements of the aerospace field and possessing good application and promotion value.

Claims

A method for preparing 1.1500MPa grade titanium alloy bars, characterized in that, Includes the following steps: S1. Select raw materials based on the chemical composition of 1500MPa grade titanium alloy bars, then weigh and batch them; The chemical composition, by mass percentage, is: V 5.5~6.5%, Mo 4.5~5.5%, Al 3.0~4.0%, Zr 2.5~3.5%, Cr 1.5~2.5%, Nb 1.5~2.5%, Fe 0.9~1.1%, with the balance being Ti and unavoidable impurities; S2. The raw materials are pressed into electrode blocks, welded to obtain consumable electrodes, and subjected to three vacuum consumable melting processes to obtain titanium alloy ingots. S3. Titanium alloy ingots are processed into bars through β-zone forging, β-zone multi-pass upsetting and drawing, two-phase zone forging, and multi-pass rolling. S4. The bar is subjected to multiple solution aging heat treatments to obtain 1500MPa grade titanium alloy bar. The multiple solution aging heat treatment is as follows: solution treatment is performed at 830℃~920℃ for 1~3 hours; then the converter is cooled to 200℃ at 640℃~730℃, and then air-cooled to room temperature; finally, aging treatment is performed at 520℃~620℃ for 5~8 hours, and then air-cooled to room temperature.

2. The method for preparing 1500MPa grade titanium alloy rods according to claim 1, characterized in that: In step S1, the impurity elements in the chemical composition of the 1500MPa grade titanium alloy bar are O<0.1%, N<0.01%, H<0.005%, and C<0.01%.

3. The method for preparing 1500MPa grade titanium alloy rods according to claim 1, characterized in that: In step S1, the raw materials include sponge titanium, aluminum briquettes, sponge zirconium, Al-60Cr, Ti-50Nb, Ti-32Mo, Al-85V, and Ti-30Fe.

4. The method for preparing 1500MPa grade titanium alloy rods according to claim 1, characterized in that: In step S2, all three vacuum self-consumption melting processes employ a sinusoidal AC arc-stabilizing current. The specific process is as follows: First time: vacuum degree ≤2Pa, arc ignition to stable melting time ≤30min, average melting rate ≤5kg / min; Second and third times: vacuum degree ≤1.5Pa, arc ignition to stable melting time ≤25min, average melting rate ≤4kg / min.

5. The method for preparing 1500MPa grade titanium alloy rods according to claim 1, characterized in that: In step S3, the temperature for the β-zone forging is 1000℃~1200℃.

6. The method for preparing 1500MPa grade titanium alloy rods according to claim 1, characterized in that: In step S3, the upsetting and drawing in the β region is performed in 2 to 4 passes, and the deformation temperature of each pass decreases gradually within the range of 900℃ to 1100℃, with the temperature decrease between adjacent passes being 50℃ to 100℃.

7. The method for preparing 1500MPa grade titanium alloy rods according to claim 1, characterized in that: In step S3, the forging temperature of the two-phase region is 800℃~950℃. First, it is forged into a square shape at 900℃≤T≤950℃, and then forged into a bar at 800℃≤T<900℃.

8. The method for preparing 1500MPa grade titanium alloy rods according to claim 1, characterized in that: In step S3, the multi-pass rolling process specifically includes: the first pass rolling temperature is 900℃~920℃, and the deformation is 7%~10%; the second and third passes rolling temperature is 840℃~860℃, and the deformation is 18%~25%; the fourth and fifth passes rolling temperature is 810℃~830℃, and the deformation is 16%~20%.

9. A 1500MPa grade titanium alloy rod prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The chemical composition of the 1500MPa grade titanium alloy bar, by mass percentage, is: V 5.5~6.5%, Mo 4.5~5.5%, Al 3.0~4.0%, Zr 2.5~3.5%, Cr 1.5~2.5%, Nb 1.5~2.5%, Fe 0.9~1.1%, with the balance being Ti and unavoidable impurities, wherein the impurity elements are controlled to be O < 0.1%, N < 0.01%, H < 0.005%, and C < 0.01%.

10. The 1500MPa grade titanium alloy bar according to claim 9, characterized in that: The 1500MPa grade titanium alloy bar has a tensile strength >1500MPa and an elongation >6%.