High-strength and high-plasticity beta titanium alloy strip and full-process preparation method thereof

Abstract

The application discloses a kind of high-strength plastic β titanium alloy strip and whole-process preparation method, the β titanium alloy strip is composed of the following mass percentage components: Cr 7.7%~8.3%, Mo 4.9%~5.5%, V 4.9%~5.5%, Al 2.7%~3.3%, Fe≤0.20%, C≤0.03%, N≤0.02%, H≤0.010%, O≤0.10%, and the rest is Ti;The preparation method comprises: one, forging;Two, hot rolling;Three, cold rolling;Four, heat treatment.The β titanium alloy strip and whole-process preparation method of the application are overall planning from component design to final heat treatment whole-process procedure, improve production efficiency, shorten preparation time, and the β titanium alloy strip solid solution state microstructure is equiaxed β fine grain structure, strength-plasticity matching is high, horizontal longitudinal organization performance is uniform, with excellent comprehensive mechanical properties, applicable to metal processing field.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal processing technology, specifically relating to a high-strength, high-ductility β-titanium alloy strip and its complete preparation method. Background Technology

[0002] In recent years, with the rapid development of my country's aerospace and communications industries, the demand for titanium alloy strips has become increasingly prominent. Beta titanium alloys possess excellent comprehensive properties and are widely used in aerospace and other military fields, where the working environment is demanding and the conditions complex. However, beta titanium alloys have complex compositions, and their microstructure and properties are highly sensitive to process factors. The execution of actual processes, the control of processing procedures, and the heat treatment of products have a significant impact on the final product's performance and quality. Furthermore, in actual production, traditional single-process or single-industry methods cannot achieve comprehensive coordination throughout the entire process, and efficient integration between various steps is difficult. Therefore, how to determine the composition and overall production process of beta titanium alloy strips, improve the strength-ductility matching, and produce strips that meet performance requirements remains a problem to be solved in the field of titanium alloy strip manufacturing. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a high-strength and high-ductility β-titanium alloy strip, addressing the shortcomings of the prior art. This invention employs a comprehensive preparation method that integrates elemental composition, processing technology, and heat treatment, ensuring a high degree of compatibility between the β-titanium alloy strip's composition and the entire preparation process. This eliminates the need for additional auxiliary processes, significantly improving the preparation efficiency of the β-titanium alloy strip. Furthermore, this β-titanium alloy strip exhibits high strength-ductility matching and excellent comprehensive mechanical properties, solving the problem of poor matching between the composition and production process in existing β-titanium alloy strip technologies.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a high-strength and high-ductility β-titanium alloy strip, characterized in that it is composed of the following components by mass percentage: Cr 7.7%–8.3%, Mo 4.9%–5.5%, V 4.9%–5.5%, Al 2.7%–3.3%, Fe≤0.20%, C≤0.03%, N≤0.02%, H≤0.010%, O≤0.10%, with the remainder being Ti; the phase transformation point of the β-titanium alloy strip is 725℃–730℃; the tensile strength Rm of the β-titanium alloy strip in the solid solution state is 849MPa–864MPa, and the yield strength Rp is… 0.2 =831MPa~844MPa, elongation after fracture A=26.5%~34%, tensile strength in aged state Rm=1135MPa~1250MPa, yield strength Rp 0.2 =1029MPa~1097MPa, elongation after fracture A =17%~23.5%.

[0005] Meanwhile, this invention also discloses a complete process preparation method for the high-strength, high-ductility β-titanium alloy strip as described above, characterized in that the method includes the following steps:

[0006] Step 1, Forging: The cylindrical β-titanium alloy ingot is forged using a heating furnace and a high-speed forging machine to obtain a forged slab;

[0007] Step 2, Hot rolling: The forged slab obtained in Step 1 is hot rolled in a heating furnace and a hot rolling mill to obtain a hot-rolled slab.

[0008] Step 3, cold rolling: The hot-rolled slab obtained in step 2 is cold-rolled multiple times through a cold rolling mill to obtain cold-rolled strip.

[0009] Step 4, Heat Treatment: The cold-rolled strip obtained in Step 3 is subjected to solution heat treatment in a vacuum annealing furnace, followed by aging heat treatment to obtain high-strength and high-ductility β-titanium alloy strip.

[0010] The above-mentioned whole-process preparation method is characterized in that the forging process in step one is as follows: a cylindrical β titanium alloy ingot is placed in a heating furnace, heated and held at a certain temperature, and then immediately taken out of the furnace for a first-fire forging to obtain a first-fire forging billet, which is then water-cooled. Then, it is placed in a heating furnace again, heated and held at a certain temperature, and then immediately taken out of the furnace for a second-fire forging to obtain a second-fire forging billet, which is then water-cooled to obtain a forged slab.

[0011] The above-described full-process preparation method is characterized in that the heating and holding temperature of the first forging is 300℃~400℃ higher than the phase transformation temperature of the β titanium alloy, and the time is 0.4~0.7 times the diameter of the cylindrical β titanium alloy ingot; the heating and holding temperature of the second forging is 130℃~180℃ higher than the phase transformation temperature of the β titanium alloy, and the time is 0.6~1.0 times the thickness of the first forging billet; and the units for diameter and thickness are mm, and the units for time are min.

[0012] The above-mentioned whole-process preparation method is characterized in that the deformation mode of the first-fire forging is radial three-upsetting and three-drawing, and the forging ratio of each upsetting or drawing is 1.5 to 1.7; the deformation mode of the second-fire forging is reverse three-upsetting and three-drawing, and the forging ratio of each upsetting or drawing is 1.8 to 2.2; and then axially drawing is performed to the target forging slab size.

[0013] The above-mentioned whole-process preparation method is characterized in that, in step two, the forged slab is placed in a heating furnace for heating and holding, and then immediately taken out of the furnace for hot rolling in one heat to obtain a hot-rolled plate in one heat. Then, the hot-rolled plate in one heat is placed in a heating furnace for reheating and holding, and then immediately taken out of the furnace for hot rolling in two heats to obtain a hot-rolled plate in two heats. Then, the hot-rolled plate in two heats is placed in a heating furnace for reheating and holding, and then immediately taken out of the furnace for hot rolling in three heats to obtain a hot-rolled plate in three heats. The plate is then water-cooled to room temperature to obtain a hot-rolled slab.

[0014] The above-described full-process preparation method is characterized in that the heating and holding temperature of the first hot rolling is 100℃~200℃ higher than the phase transformation temperature of the β titanium alloy, and the time is 1.0~1.4 times the thickness of the forged slab; the reheating and holding temperature of the second hot rolling is 50℃~100℃ higher than the phase transformation temperature of the β titanium alloy, and the time is 0.8~1.2 times the thickness of the first hot rolled plate; the reheating and holding temperature of the third hot rolling is 20℃~50℃ lower than the phase transformation temperature of the β titanium alloy, and the time is 0.6~1.0 times the thickness of the second hot rolled plate. All thicknesses are in mm, and all times are in min.

[0015] The above-mentioned whole-process preparation method is characterized in that the total deformation of each of the first-pass hot rolling, second-pass hot rolling and third-pass hot rolling is 60% to 80% of the corresponding incoming material thickness, and the deformation per pass is 10% to 30% of the corresponding incoming material thickness.

[0016] The above-mentioned whole-process preparation method is characterized in that, in step three, after the surface treatment of the hot-rolled slab, the head and tail are welded with lead strips and then cold-rolled in multiple passes by a cold rolling mill, and the total deformation of the multiple cold rolling passes is 50% to 90% of the thickness of the incoming material, and the deformation of a single pass is 5% to 15% of the thickness of the incoming material.

[0017] The above-mentioned whole-process preparation method is characterized in that, in step four, the cold-rolled strip is subjected to solution heat treatment in a vacuum annealing furnace at a temperature of 740℃~840℃ for 30min~60min, and then cooled by high-purity argon gas quenching. After that, it is subjected to aging heat treatment at a temperature of 450℃~550℃ for 4h~12h, and then cooled in the furnace.

[0018] In this invention, "incoming material" refers to the processing object corresponding to each process.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. Compared to existing β-titanium alloy strip preparation technologies that only focus on researching or improving a single process or method, resulting in unclear alloy composition or grade, leading to a lack of systematic approach and poor matching between the prepared material and the process, this invention starts from the alloy composition and designs a complete preparation method that requires all three elements—elemental composition, processing technology, and heat treatment method—to ensure a high degree of consistency between the composition of the β-titanium alloy strip and its entire preparation method. No additional assistance is needed, significantly improving the preparation efficiency of β-titanium alloy strip. Furthermore, this β-titanium alloy strip exhibits high strength-plasticity matching and excellent comprehensive mechanical properties, making it suitable for the metal processing field.

[0021] 2. The β-titanium alloy strip of the present invention ensures that the titanium alloy is a stable β-titanium alloy with a low phase transformation point by strictly controlling the molybdenum equivalent. Combined with a reasonable solution treatment and aging heat treatment process, a uniform equiaxed microstructure with β phase as the matrix and α phase dispersed is obtained, so that the β-titanium alloy strip has a high strength-plasticity matching, thereby obtaining excellent comprehensive mechanical properties.

[0022] 3. Compared with the traditional forging process for strip preparation which only meets the requirements for slab forming, the forging process adopted in this invention improves the uniformity of the microstructure of the forged slab. In particular, the temperature of the final forging is reduced to 30°C to 80°C above the phase transformation temperature of β-titanium alloy, and the forging ratio is increased to 1.8 to 2.2. That is, a lower temperature and a larger deformation amount are used to obtain a more uniform and fine forging microstructure, thereby reducing the processing difficulty of subsequent processes.

[0023] 4. This invention controls the hot rolling process and rolling temperature, especially reducing the temperature of the last hot rolling pass to 20°C to 50°C below the phase transformation point of β titanium alloy, and increasing the hot rolling deformation to introduce the α phase during the hot rolling process. The α phase and the residual β phase participate in the deformation together, increasing the number of recrystallization nucleation points in the microstructure, improving the internal distortion energy of the microstructure, effectively suppressing the coarsening of the original β grains, and providing a fine-grained slab for the next cold rolling process. The grain refinement hinders the resistance to dislocation movement, thereby increasing the strength of the β titanium alloy strip and reducing the dislocation density dispersed in each grain. This allows the β titanium alloy strip to undergo large plastic deformation without causing large stress concentration that could lead to material cracking, while also improving the plasticity of the β titanium alloy strip.

[0024] 5. This invention employs water cooling during the forging process and gas quenching after solution heat treatment, strictly controlling the cooling rate after each processing step. In particular, the use of high-purity argon gas quenching after solution heat treatment eliminates grain growth and α-phase precipitation during slow cooling, preserves fine-grained structure, and effectively improves the strength-plasticity matching of β-titanium alloy strip.

[0025] 6. This invention is designed for the composition of β-titanium alloy strip and a complete processing technology is developed for it. The overall process is efficient and concise, the processing equipment and equipment requirements are simple, the production cost is reduced, and β-titanium alloy strip with good strength-plasticity matching, excellent comprehensive mechanical properties and smooth surface is obtained, which is easy to promote.

[0026] In summary, this invention integrates the entire process of alloy strip production, from composition design to final heat treatment, with each step seamlessly connected. The billets produced in each step fully meet the requirements of the next step, eliminating the need for additional processing and significantly improving actual production efficiency and shortening preparation time. This overcomes the limitations of single-process or single-step methods in traditional models. Furthermore, the β-titanium alloy strip prepared by this invention exhibits an equiaxed β-fine-grained microstructure in its solid solution state, demonstrating high strength-plasticity matching and uniform transverse and longitudinal microstructure. Especially after aging treatment, it possesses excellent comprehensive mechanical properties.

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0028] Figure 1 This is a schematic flowchart of the entire process for preparing the high-strength, ductile β-titanium alloy strip of the present invention. Detailed Implementation

[0029] Example 1

[0030] like Figure 1 As shown, this embodiment includes the following steps:

[0031] Step 1: Forging: The raw materials are prepared according to the composition of the target product, β-titanium alloy strip, and then melted in a vacuum electric arc furnace to obtain a cylindrical β-titanium alloy ingot. Testing revealed that the cylindrical β-titanium alloy ingot consists of the following components by mass percentage: Cr 8.24%, Mo 5.11%, V 5.37%, Al 2.79%, Fe 0.185%, C 0.008%, N 0.009%, H 0.009%, O 0.03%, with the remainder being Ti. The phase transformation point of the β-titanium alloy strip is 725℃~730℃.

[0032] After removing defects, a cylindrical β-titanium alloy ingot with a diameter × height of Φ440mm × 710mm is placed in a heating furnace and heated at 1030℃ for 180 minutes. It is then immediately removed from the furnace for first-fire forging. The deformation method of the first-fire forging is radial three-upsetting and three-drawing, and the forging ratio of each upsetting or drawing is 1.5 to 1.7, resulting in a first-fire forged square billet with a side length × length of Φ350mm × 880mm. The billet is then water-cooled and placed in a heating furnace for heating at 860℃ for 260 minutes. It is then immediately removed from the furnace for second-fire forging. The deformation method of the second-fire forging is reverse three-upsetting and three-drawing, and the forging ratio of each upsetting or drawing is 1.8 to 2.2. The billet is then axially drawn to a second-fire forged billet with a thickness × width × length of δ100mm × 510mm × Lmm and water-cooled to obtain a forged slab.

[0033] Step 2, Hot Rolling: The forged slab obtained in Step 1 is placed in a heating furnace and heated at 930℃ for 100 minutes. It is then immediately taken out of the furnace for one-fire hot rolling. The total deformation of the one-fire hot rolling is 80% of the thickness of the forged slab, and the deformation per pass is 10% to 30% of the thickness of the forged slab. The resulting one-fire hot-rolled plate has a thickness × width × length of δ20mm × 510mm × Lmm.

[0034] Then, the first-fire hot-rolled plate is placed in a heating furnace and heated at 830℃ for 25 minutes. After that, it is immediately taken out of the furnace for second-fire hot rolling. The total deformation of the second-fire hot rolling is 80% of the thickness of the first-fire hot-rolled plate, and the deformation per pass is 10% to 30% of the thickness of the first-fire hot-rolled plate. The resulting second-fire hot-rolled plate has a thickness × width × length of δ4mm × 510mm × Lmm. It is then water-cooled to room temperature to obtain a hot-rolled slab.

[0035] Step 3, Cold Rolling: After surface treatment of the hot-rolled slab obtained in Step 2, lead strips are welded to the head and tail respectively. The slab is then subjected to multiple cold rolling passes on a cold rolling mill. The total deformation of the multiple cold rolling passes is 75% of the thickness of the hot-rolled slab, and the deformation of a single pass is 5% to 15% of the thickness of the hot-rolled slab. A cold-rolled strip with dimensions of δ1mm × 510mm × Lmm (thickness × width × length) is obtained.

[0036] Step 4, Heat Treatment: The cold-rolled strip obtained in Step 3 is subjected to solution heat treatment in a vacuum annealing furnace at 740℃ for 60 minutes, followed by quenching with argon gas of 99.99% purity. Then, it is subjected to aging heat treatment at 450℃ for 12 hours and cooled in the furnace.

[0037] Testing revealed that the β-titanium alloy strip prepared in this embodiment exhibited a tensile strength Rm of 849 MPa and a yield strength Rp in the solid solution state. 0.2 =831MPa, elongation after fracture A=34%, tensile strength Rm=1135MPa in aged state, yield strength Rp 0.2 =1029MPa, elongation after fracture A =23.5%.

[0038] Example 2

[0039] like Figure 1 As shown, this embodiment includes the following steps:

[0040] Step 1: Forging: The raw materials are prepared according to the composition of the target product, β-titanium alloy strip, and then melted in a vacuum electric arc furnace to obtain a cylindrical β-titanium alloy ingot. Testing revealed that the cylindrical β-titanium alloy ingot consists of the following components by mass percentage: Cr 7.92%, Mo 5.41%, V 4.95%, Al 3.12%, Fe 0.032%, C 0.012%, N 0.016%, H 0.002%, O 0.05%, with the remainder being Ti. The phase transformation point of the β-titanium alloy strip is 725℃~730℃.

[0041] After removing defects, a cylindrical β-titanium alloy ingot with a diameter × height of Φ440mm × 710mm is placed in a heating furnace and heated at 1080℃ for 260min. It is then immediately removed from the furnace for first-fire forging. The deformation method of the first-fire forging is radial three-upsetting and three-drawing, and the forging ratio of each upsetting or drawing is 1.5 to 1.7, resulting in a first-fire forged square billet with a side length × length of □350mm × 880mm. The billet is then water-cooled and placed in a heating furnace for heating at 885℃ for 210min. It is then immediately removed from the furnace for second-fire forging. The deformation method of the second-fire forging is reverse three-upsetting and three-drawing, and the forging ratio of each upsetting or drawing is 1.8 to 2.2. The billet is then axially drawn to a second-fire forged billet with a thickness × width × length of δ100mm × 510mm × Lmm and water-cooled to obtain a forged slab.

[0042] Step 2, Hot Rolling: The forged slab obtained in Step 1 is placed in a heating furnace and heated at 880℃ for 120 minutes. It is then immediately taken out of the furnace for one-fire hot rolling. The total deformation of the one-fire hot rolling is 70% of the thickness of the forged slab, and the deformation per pass is 10% to 30% of the thickness of the forged slab. The resulting one-fire hot-rolled plate has a thickness × width × length of δ30mm × 510mm × Lmm.

[0043] Then, the first-fire hot-rolled plate is placed in a heating furnace and heated at 810℃ for 30 minutes. After that, it is immediately taken out of the furnace for second-fire hot rolling. The total deformation of the second-fire hot rolling is 66% of the thickness of the first-fire hot-rolled plate, and the deformation per pass is 10% to 30% of the thickness of the first-fire hot-rolled plate. The resulting second-fire hot-rolled plate has a thickness × width × length of δ10mm × 510mm × Lmm.

[0044] The second-fire hot-rolled plate is then placed in a heating furnace and heated at 710℃ for 10 minutes. It is then immediately taken out of the furnace for third-fire hot rolling. The total deformation of the third-fire hot rolling is 80% of the thickness of the second-fire hot-rolled plate, and the deformation per pass is 10% to 30% of the thickness of the second-fire hot-rolled plate. The resulting third-fire hot-rolled plate has a thickness × width × length of δ2mm × 510mm × Lmm. It is then water-cooled to room temperature to obtain a hot-rolled slab.

[0045] Step 3, Cold Rolling: After surface treatment of the hot-rolled slab obtained in Step 2, lead strips are welded to the head and tail respectively. The slab is then subjected to multiple cold rolling passes on a cold rolling mill. The total deformation of the multiple cold rolling passes is 50% of the thickness of the hot-rolled slab, and the deformation of a single pass is 5% to 15% of the thickness of the hot-rolled slab. A cold-rolled strip with dimensions of δ1mm × 510mm × Lmm (thickness × width × length) is obtained.

[0046] Step 4, Heat Treatment: The cold-rolled strip obtained in Step 3 is passed through a vacuum annealing furnace at a vacuum degree of not less than 10. -3 Solution heat treatment was performed at 790℃ for 45 minutes, followed by quenching with argon gas of 99.99% purity. Then, aging heat treatment was performed at 500℃ for 8 hours, and the furnace was cooled.

[0047] Testing revealed that the β-titanium alloy strip prepared in this embodiment exhibited a tensile strength Rm of 855 MPa and a yield strength Rp in the solid solution state. 0.2 =837MPa, elongation after fracture A = 29.5%, tensile strength in aged state Rm = 1191MPa, yield strength Rp 0.2 =1054MPa, elongation after fracture A =20.5%.

[0048] Example 3

[0049] like Figure 1 As shown, this embodiment includes the following steps:

[0050] Step 1: Forging: The raw materials are prepared according to the composition of the target product, β-titanium alloy strip, and melted in a vacuum electric arc furnace to obtain a cylindrical β-titanium alloy ingot. Testing revealed that the cylindrical β-titanium alloy ingot consists of the following components by mass percentage: Cr 7.76%, Mo 4.93%, V 5.31%, Al 3.26%, Fe 0.098%, C 0.023%, N 0.006%, H 0.004%, O 0.07%, with the remainder being Ti. The phase transformation point of the β-titanium alloy strip is 725℃~730℃.

[0051] After removing defects, a cylindrical β-titanium alloy ingot with a diameter × height of Φ440mm × 710mm is placed in a heating furnace and heated at 1130℃ for 310 minutes. It is then immediately removed from the furnace for first-fire forging. The deformation method of the first-fire forging is radial three-upsetting and three-drawing, and the forging ratio of each upsetting or drawing is 1.5 to 1.7, resulting in a first-fire forged square billet with a side length × length of □350mm × 880mm. The billet is then water-cooled and placed in a heating furnace again. It is then heated at 910℃ for 350 minutes and immediately removed from the furnace for second-fire forging. The deformation method of the second-fire forging is reverse three-upsetting and three-drawing, and the forging ratio of each upsetting or drawing is 1.8 to 2.2. The billet is then axially drawn to a second-fire forged billet with a thickness × width × length of δ100mm × 510mm × Lmm and water-cooled to obtain a forged slab.

[0052] Step 2, Hot Rolling: The forged slab obtained in Step 1 is placed in a heating furnace and heated at 830℃ for 140 minutes. It is then immediately taken out of the furnace for one-fire hot rolling. The total deformation of the one-fire hot rolling is 60% of the thickness of the forged slab, and the deformation per pass is 10% to 30% of the thickness of the forged slab. The resulting one-fire hot-rolled plate has a thickness × width × length of δ40mm × 510mm × Lmm.

[0053] Then, the first-fire hot-rolled plate is placed in a heating furnace and heated at 780℃ for 30 minutes. After that, it is immediately taken out of the furnace for second-fire hot rolling. The total deformation of the second-fire hot rolling is 60% of the thickness of the first-fire hot-rolled plate, and the deformation per pass is 10% to 30% of the thickness of the first-fire hot-rolled plate. The resulting second-fire hot-rolled plate has a thickness × width × length of δ16mm × 510mm × Lmm.

[0054] The second-fire hot-rolled plate is then placed in a heating furnace and heated at 680℃ for 9.6 minutes. It is then immediately taken out of the furnace for third-fire hot rolling. The total deformation of the third-fire hot rolling is 60% of the thickness of the second-fire hot-rolled plate, and the deformation per pass is 10% to 30% of the thickness of the second-fire hot-rolled plate. The resulting third-fire hot-rolled plate has a thickness × width × length of δ6.4mm × 510mm × Lmm. It is then water-cooled to room temperature to obtain a hot-rolled slab.

[0055] Step 3, Cold Rolling: After surface treatment of the hot-rolled slab obtained in Step 2, lead strips are welded to the head and tail respectively. The slab is then subjected to multiple cold rolling passes on a cold rolling mill. The total deformation of the multiple cold rolling passes is 90% of the thickness of the hot-rolled slab, and the deformation of a single pass is 5% to 15% of the thickness of the hot-rolled slab. A cold-rolled strip with dimensions of δ0.64mm × 510mm × Lmm (thickness × width × length) is obtained.

[0056] Step 4, Heat Treatment: The cold-rolled strip obtained in Step 3 is passed through a vacuum annealing furnace at a vacuum degree of not less than 10. -3Solution heat treatment was performed at 840℃ for 30 minutes, followed by quenching with argon gas of 99.99% purity. Then, aging heat treatment was performed at 550℃ for 4 hours, and the furnace was cooled.

[0057] Testing revealed that the β-titanium alloy strip prepared in this embodiment exhibited a tensile strength Rm of 864 MPa and a yield strength Rp in the solid solution state. 0.2 =844MPa, elongation after fracture A = 26.5%, tensile strength in aged state Rm = 1250MPa, yield strength Rp 0.2 =1097MPa, elongation after fracture A =17%.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A high-strength, high-ductility β-titanium alloy strip, characterized in that, The β-titanium alloy strip is composed of the following components by mass percentage: Cr 7.7%~8.3%, Mo 4.9%~5.5%, V 4.9%~5.5%, Al 2.7%~3.3%, Fe≤0.20%, C≤0.03%, N≤0.02%, H≤0.010%, O≤0.10%, with the remainder being Ti; the phase transformation point of the β-titanium alloy strip is 725℃~730℃; the tensile strength Rm of the β-titanium alloy strip in the solid solution state is 849MPa~864MPa, and the yield strength Rp is... 0.2 =831MPa~844MPa, elongation after fracture A=26.5%~34%, tensile strength in aged state Rm=1135MPa~1250MPa, yield strength Rp 0.2 =1029MPa~1097MPa, elongation after fracture A=17%~23.5%; The complete process for preparing the high-strength, ductile β-titanium alloy strip includes the following steps: Step 1, Forging: The cylindrical β-titanium alloy ingot is forged using a heating furnace and a high-speed forging mill to obtain a forged slab. The forging process is as follows: the cylindrical β-titanium alloy ingot is placed in a heating furnace, heated and held at a certain temperature, and then immediately removed from the furnace for a first-fire forging to obtain a first-fire forged slab, which is then water-cooled. Then, it is placed back in the heating furnace, heated and held at a certain temperature, and immediately removed from the furnace for a second-fire forging to obtain a second-fire forged slab, which is then water-cooled to obtain the forged slab. The heating and holding temperature of the first-fire forging is... The phase transformation temperature of the first forging is 300℃~400℃ higher than that of β titanium alloy, and the heating and holding temperature of the second forging is 130℃~180℃ higher than that of β titanium alloy. The deformation method of the first forging is radial three upsetting and three drawing, and the forging ratio of each upsetting or drawing is 1.5~1.

7. The deformation method of the second forging is reverse three upsetting and three drawing, and the forging ratio of each upsetting or drawing is 1.8~2.

2. Then, it is axially drawn to the target forging slab size. Step Two, Hot Rolling: The forged slab obtained in Step One is hot rolled using a heating furnace and a hot rolling mill. After being heated and held at a certain temperature in the heating furnace, the slab is immediately removed and hot-rolled for the first heat, resulting in a first-heat hot-rolled plate. This first-heat hot-rolled plate is then returned to the heating furnace for reheating and holding before being immediately removed and hot-rolled for the second heat, resulting in a second-heat hot-rolled plate. This second-heat hot-rolled plate is then returned to the heating furnace for reheating and holding before being immediately removed and hot-rolled for the third heat, resulting in a third-heat hot-rolled plate. Finally, the plate is water-cooled to room temperature to obtain the hot-rolled slab. The heating and holding temperature of the first-pass hot rolling is 100℃~200℃ higher than the phase transformation temperature of the β-titanium alloy; the reheating and holding temperature of the second-pass hot rolling is 50℃~100℃ higher than the phase transformation temperature of the β-titanium alloy; and the reheating and holding temperature of the third-pass hot rolling is 20℃~50℃ lower than the phase transformation temperature of the β-titanium alloy. The total deformation of each of the first-pass, second-pass, and third-pass hot rolling processes is 60%~80% of the corresponding incoming material thickness, and the deformation per pass is 10%~30% of the corresponding incoming material thickness. Step 3, cold rolling: The hot-rolled slab obtained in step 2 is cold-rolled multiple times through a cold rolling mill to obtain cold-rolled strip. Step 4, Heat Treatment: The cold-rolled strip obtained in Step 3 is subjected to solution heat treatment in a vacuum annealing furnace at a temperature of 740℃~840℃ for 30min~60min, followed by quenching with high-purity argon gas, and then aging heat treatment at a temperature of 450℃~550℃ for 4h~12h, and then cooled in the furnace to obtain high-strength PVC-U alloy strip.

2. The high-strength, high-ductility β-titanium alloy strip according to claim 1, characterized in that, In step one, the heating and holding time for the first forging is 0.4 to 0.7 times the diameter of the cylindrical β-titanium alloy ingot, and the heating and holding time for the second forging is 0.6 to 1.0 times the thickness of the billet for the first forging. The units for diameter and thickness are mm, and the units for time are min.

3. The high-strength, high-ductility β-titanium alloy strip according to claim 1, characterized in that, In step two, the heating and holding time for the first hot rolling is 1.0 to 1.4 times the thickness of the forged slab, the heating and holding time for the second hot rolling is 0.8 to 1.2 times the thickness of the first hot rolling, and the heating and holding time for the third hot rolling is 0.6 to 1.0 times the thickness of the second hot rolling. All thicknesses are in mm and all times are in min.

4. The high-strength, high-ductility β-titanium alloy strip according to claim 1, characterized in that, In step three, after surface treatment of the hot-rolled slab, guide strips are welded to the head and tail respectively, and the slab is subjected to multiple cold rolling passes through a cold rolling mill. The total deformation of the multiple cold rolling passes is 50% to 90% of the thickness of the incoming material, and the deformation of a single pass is 5% to 15% of the thickness of the incoming material.

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