Manufacturing method of ultrahigh-strength and high-toughness Ti-6Al-4V alloy plate

Abstract

The invention relates to a manufacturing method of an ultrahigh-strength and high-toughness Ti-6Al-4V alloy plate. A preparation process comprises a high-temperature solution treatment process, a large-deformation rolling process and a structure ultrafine gradient heat treatment process. Compared with the prior art, the average grain size of the prepared ultrafine lamellar structure Ti-6Al-4V alloy ranges from 150 nm to 400 nm, the yield strength is not lower than 1200 MPa, the tensile strength is not lower than 1500 MPa, and the ductility is not lower than 8.0%. The composite material has ultrahigh strength and high toughness, and shows good comprehensive mechanical properties. According to the technology, the structure is refined through conventional equipment and a production technology, lamellar structure refining can be achieved, a large number of separated nano-particles are dispersed and distributed in a matrix, the comprehensive mechanical property of the alloy is remarkably improved, the technology is simple and easy to implement, common industrial equipment can be used for implementation, the production efficiency is high, and industrial production and application are easy.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy material processing, and in particular relates to a method for manufacturing an ultra-high-strength and high-toughness Ti-6Al-4V alloy plate. Background Art

[0002] Ti-6Al-4V alloy, as a widely used titanium alloy material, plays an important role in aerospace, medical equipment and many industrial fields due to its excellent mechanical properties and good corrosion resistance. With the advancement of science and technology and the development of industry, the requirements for material properties are also increasing, especially in terms of high strength and high toughness.

[0003] Grain (structure) refinement is an effective way to improve both the strength and toughness of materials. In recent years, research on the preparation of ultrafine grains (UFG, less than 1 micron) or nanocrystalline (NG, less than 100 nanometers) materials using severe plastic deformation (SPD) has attracted widespread attention from materials scholars. Commonly used methods for intense plastic deformation include heavy deformation rolling (HDR): it can achieve large-scale continuous production, with low requirements on the shape and size of the material, but with high requirements on the control of rolling equipment and process parameters; high pressure torsion (HPT): it can significantly refine the grains to ultrafine or nanocrystalline levels and improve the mechanical and physical properties of the material, but it has certain restrictions on the size and shape of the specimen, the equipment cost is high, and it is difficult to achieve large-scale production; equal-channel angular extrusion or pressing (ECAE / ECAP): it can significantly refine the grains, evenly distribute the grain size, and improve the mechanical properties of the material, but it has high requirements on mold design and low production efficiency, and it cannot achieve large-scale production; cumulative roll bonding (ARB): it can achieve the preparation of large blocks of ultrafine-grained materials, and the process is relatively simple, but the process flow is long, and there may be quality problems at the welding interface.

[0004] Patent document CN 116060470 B provides a titanium alloy TA32 thick plate and its preparation method. The intermediate thickness of the invention is fully deformed in the two-phase temperature range of 920-960°C, and the processing temperature range is gradually reduced to 930-950°C, effectively weakening the phase change texture of the plate. In addition, the 550°C titanium alloy TA32 thick plate prepared by the method described in the invention has uniform microstructure, excellent room temperature tensile properties and endurance properties, and stable mechanical properties. However, the TA32 plate prepared by this method has a low tensile strength of only 900MPa, which cannot meet the urgent needs of modern industry for high-performance titanium alloys.

[0005] Patent document CN 115971249 A provides a method for preparing ultra-thin TC4 titanium alloy sheet, the steps of which include hot rolling, hot rolling, quenching, hot rolling, double-sheet stacking, steel plate cladding rolling, cold rolling and step annealing. The double-sheet stacking and steel plate cladding rolling used in the invention effectively overcome the rolling limit of the minimum thickness of the hot rolling mill, and greatly improve the production efficiency while optimizing the organization. In particular, the double-sheet stacking is arranged before the steel plate cladding rolling, which can provide high-precision slabs for the steel plate cladding rolling efficiently and at low cost, which is conducive to giving full play to the characteristics of the steel plate cladding rolling, and effectively obtaining a clad slab with thin thickness and good uniformity; on the whole, it also reduces the subsequent cold rolling pressure, and can effectively play the effect of high surface quality of cold rolling. However, the average grain size of the sheet prepared by this method is between 2.8 and 7.0 μm, which seriously limits the upper limit of the mechanical properties of the sheet, which is only about 1100 MPa.

[0006] Although traditional manufacturing methods can regulate the properties of Ti-6Al-4V alloy, it is difficult to achieve high strength and high toughness at the same time. The present invention aims to make the product have both high strength and high toughness. It adopts a process combining large deformation rolling and heat treatment. Large deformation rolling reshapes the internal structure of the material, and heat treatment further optimizes the structure. The two complement each other and refine the grain size of the material to 150-400nm. The material organization is ultrafine lamellar organization + nano-precipitation phase, which improves the strength of the material while maintaining good toughness of the material. Therefore, the present invention intends to provide a method for manufacturing ultra-high strength and high toughness Ti-6Al-4V alloy sheet, so that the material has both high strength and high toughness. Summary of the invention

[0007] The purpose of the present invention is to provide a method for manufacturing an ultra-high-strength and high-toughness Ti-6Al-4V alloy plate in order to overcome the defects of the above-mentioned prior art. The method adopts a combination of large deformation rolling and heat treatment process to significantly refine the alloy structure, and realizes the dual improvement of strength and toughness of Ti-6Al-4V alloy through ultra-fine lamellar structure. The process is simple and easy, can be realized by general industrial equipment, has high production efficiency, and is easy to industrialize.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] A method for manufacturing an ultra-high-strength and high-toughness Ti-6Al-4V alloy plate comprises the following steps:

[0010] Step 1 High temperature solution treatment: The initial alloy is placed in (T β +20~T β Carry out sufficient heat preservation treatment in a heat treatment furnace at +50)℃ and cool to room temperature;

[0011] Step 2: large deformation rolling: the material after the solution treatment in step 1 is subjected to large deformation rolling processing, and the large deformation rolling adopted is any one of the four methods of high temperature hot rolling + large deformation warm rolling, large deformation warm rolling, large deformation warm rolling + cold rolling, high temperature hot rolling + large deformation warm rolling + cold rolling;

[0012] Step 3: Ultrafine organization gradient heat treatment: The plate of step 2 is subjected to gradient heat treatment organization control, and any one of the three methods of low temperature + medium temperature short-time continuous annealing, high temperature short-time annealing + quenching + low temperature tempering, low temperature annealing + high temperature short-time insulation + quenching is adopted to obtain a Ti-6Al-4V alloy plate with ultrafine organization structure.

[0013] Preferably, in the large deformation rolling described in step 2, the rolling method adopts large deformation asynchronous rolling or large deformation asynchronous rolling + synchronous rolling, the speed ratio of asynchronous rolling is 1.2 to 2.0, and the total rolling deformation is not less than 90%; in the ultra-fine organization gradient heat treatment described in step 3, the temperature of low-temperature annealing treatment is not higher than 300°C, the temperature of medium-temperature short-time heat treatment is 500 to 700°C, the temperature of high-temperature short-time heat treatment is 850 to 1150°C, and the short-time insulation time is not higher than 30min.

[0014] Preferably, in the large deformation rolling described in step 2, high-temperature hot rolling + large deformation warm rolling are adopted, wherein: the large deformation warm rolling adopts asynchronous rolling + synchronous rolling, and the total deformation is not less than 92%, and the final rolled plate thickness is 2.0 mm and below; in the ultra-fine organization gradient heat treatment described in step 3, a high-temperature short-time annealing + quenching + low-temperature tempering process is adopted, the high-temperature short-time heat treatment temperature is 950-1050°C, the short-time holding time is not higher than 10min, and the low-temperature annealing temperature is not higher than 300°C.

[0015] Preferably, in the large deformation rolling described in step 2, asynchronous rolling + synchronous rolling is adopted, the asynchronous rolling deformation is not less than 85%, the synchronous rolling deformation is not less than 10%, the total deformation is not less than 95%, and the final rolled plate thickness is 1.5 mm or less; in the ultra-fine organization gradient heat treatment described in step 3, a high temperature short-time annealing + quenching + low temperature tempering process is adopted, the high temperature short-time treatment temperature is 1000-1050°C, the short-time insulation time is 2.0-5.0min, the low temperature annealing treatment is 250-300°C, and the insulation time is 20-30min.

[0016] Furthermore, in step 1, in the high temperature solution treatment, a stepwise gradient heating method is adopted, and Tr~(T β The heating rate from (T -200)℃ is 180~240℃ / h, (T β -200)℃ and the heating rate is 60~80℃ / h, where T r It is room temperature.

[0017] Furthermore, the large deformation asynchronous rolling used in step 2 is any one of the three methods: the roller diameters are the same but the rotation speeds are different, the roller diameters are different but the rotation speeds are the same, or the roller diameters and rotation speeds are different.

[0018] Furthermore, in step 2, in the large deformation rolling, the first pass is a single rolling along the width direction of the slab; the second pass is to rotate the slab 90° and perform a single rolling along the length direction of the slab.

[0019] Furthermore, the high-temperature hot rolling used in step 2 for large deformation rolling is heating at 950-1100°C for 20-30 minutes, performing 3-6 passes of reversing hot rolling, and the final rolling temperature is not less than 900°C; the large deformation warm rolling is performing 2-3 continuous warm rolling passes at 700-850°C; and the cold rolling is performing 2 continuous rolling passes at room temperature.

[0020] Furthermore, after the treatment in step 2, Ti-6Al-4V is a typical β transformation structure, that is, an ultra-fine lamellar structure with thin layers of lamellar β phase distributed in the middle of the α lamellae, presenting fine microscopic shear bands with an average size of 100 to 150 nm.

[0021] The alloy is remarkably refined by large deformation rolling and undergoes dynamic recrystallization above the recrystallization temperature. The refinement of the structure increases the number of grain boundaries per unit area, and the blockage effect of grain boundaries on dislocations increases the resistance to dislocation movement and the strength of the material. When relatively small grains are deformed, dislocations can be initiated in more grains, and the deformation between different grains is easier to coordinate, delaying the occurrence of stress concentration and fracture, thereby improving the plasticity of the alloy while maintaining high strength. A large number of dislocations gathered at the grain boundaries become heterogeneous nucleation points (discontinuous dynamic recrystallization) or small low-angle subgrains directly transform into high angles (continuous dynamic recrystallization products) during severe deformation, introducing high-density dislocations and high lattice distortion, which plays a significant role in improving the strength and hardness of the material.

[0022] Furthermore, in the step (3) of the ultra-fine organization gradient heat treatment, a low temperature + medium temperature short-time continuous annealing process is adopted, and the final material organization maintains a lamellar structure, and a large number of dispersedly distributed nano-precipitates are distributed in the matrix of the lamellar organization; a high temperature short-time annealing + quenching + low temperature tempering or a low temperature annealing + high temperature short-time insulation + quenching process is adopted, and the high temperature short-time time is less than 10 minutes, and the final material organization basically retains the macroscopic structural characteristics of the lamellar, that is, the α+β two-phase ultra-fine lamellar organization structure and the dispersedly distributed nano-precipitates; a high temperature short-time annealing + quenching + low temperature tempering or a low temperature annealing + high temperature short-time insulation + quenching process is adopted, and the high temperature short-time time exceeds 10 minutes, and the final material organization is transformed into an ultra-fine equiaxed (α+β) phase and a hexagonal martensite α' phase dispersedly distributed in the β phase, and the average grain size is 150 to 400nm.

[0023] Furthermore, the alloy sheet prepared by this process has a yield strength of not less than 1000 MPa, a tensile strength of not less than 1200 MPa, and a total elongation of not less than 5.0%.

[0024] Furthermore, the yield strength of the alloy sheet with the ultrafine lamellar structure prepared by the preferred process is not less than 1200 MPa, the tensile strength is not less than 1500 MPa, and the elongation is not less than 8.0%.

[0025] By using ultra-fine organization gradient heat treatment, the alloy will produce hexagonal martensite α' phase and metastable β phase during low temperature and medium temperature annealing, and dispersed α and β nano-precipitation phases will be formed during the aging process, resulting in dispersion strengthening, increased strength and hardness. During high temperature annealing, the plastically deformed Ti-6Al-4V organization will recrystallize, the recrystallized grains will grow and gradually decompose the original lamellar organization, and ultra-fine grain equiaxed β phase and equiaxed α phase will be obtained, with an average grain size of 150-400nm, giving the alloy excellent comprehensive mechanical properties.

[0026] In the present invention, Ti-6Al-4V alloy is used as raw material, and the Ti-6Al-4V alloy is treated by high temperature solid solution treatment, large deformation rolling, and ultra-fine structure gradient heat treatment. Compared with the prior art, the present invention has the following advantages:

[0027] 1. The process of the present invention refines the grain structure of the alloy and introduces a dispersed strengthening phase through several steps of high-temperature solid solution, rolling and blanking, large deformation rolling, gradient temperature rolling and ultra-fine organization gradient heat treatment, thereby effectively improving the mechanical properties of the alloy. The final tensile strength is not less than 1200MPa, the tensile strength is not less than 1500MPa, and the elongation is not less than 8.0%, showing excellent strength and toughness.

[0028] 2. The process of this patent can significantly improve the internal structure of Ti-6Al-4V alloy. After large deformation rolling treatment, the alloy presents a typical β transformation structure, that is, an α+β dual-phase ultrafine lamellar structure, and presents fine microscopic shear bands. In addition, after the ultra-fine gradient heat treatment, the alloy either maintains the original ultra-fine lamellar structure, or transforms into an equiaxed α+β phase and a hexagonal martensite α' phase dispersed in the β phase. At the same time, there are a large number of nano-precipitations in the matrix. This optimized structure provides the alloy with better mechanical properties and durability.

[0029] 3. The deformation heat treatment process provided by this patent has high flexibility and applicability. By adjusting parameters such as temperature, time and deformation in each step, the properties of the alloy can be precisely controlled. In addition, the process is suitable for Ti-6Al-4V alloy raw materials in different original states (such as cast, hot-rolled, annealed or solution-aged), further expanding its scope of application. This flexibility enables the process to customize the properties of the alloy according to different needs and meet the requirements of diverse engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The process flow chart of the preparation method of the present invention is shown;

[0031] Figure 2 The heat treatment process diagram of Example 1 is shown;

[0032] Figure 3 The tissue morphology photograph of Example 1 is shown;

[0033] Figure 4 The heat treatment process diagram of Example 2 is shown;

[0034] Figure 5 A photograph of the structure morphology of Example 2 is shown. DETAILED DESCRIPTION

[0035] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

[0036] Example 1

[0037] A method for manufacturing an ultra-high-strength and high-toughness Ti-6Al-4V alloy plate, the steps of which are as follows:

[0038] Step 1 High temperature solution treatment: Place the Ti-6Al-4V raw material in a heat treatment furnace at 1015°C for 3 hours, cool to room temperature, T β 995℃;

[0039] Step 2: large deformation rolling: the material after the solution treatment in step 1 is subjected to large deformation rolling processing, and the large deformation rolling adopted is a high temperature hot rolling + large deformation warm rolling method. The material after the treatment in step 1 is first heated at 1055°C for 28 minutes, and then subjected to 3 passes of reversing hot rolling, with a final rolling temperature of 910°C to obtain a hot-rolled slab, and then cooled to 790°C for 2 passes of continuous warm rolling to obtain a plate;

[0040] Step 3: Ultrafine organization gradient heat treatment: The plate obtained in step 2 is subjected to gradient heat treatment organization control, and a low-temperature + medium-temperature short-time continuous annealing method is adopted. The plate obtained in step 2 is placed in a heat treatment furnace, firstly subjected to low-temperature annealing at 250°C for 8 minutes, and then subjected to medium-temperature annealing at 650°C for 8 minutes to obtain a Ti-6Al-4V alloy plate with an ultrafine organization structure.

[0041] The Ti-6Al-4V alloy plate prepared by the method of the present invention has a grain size of 275nm, is ultrafine grain, and has a uniform structure; a yield strength of 1230MPa, a tensile strength of 1350MPa, and a total elongation of 7.0%.

[0042] Example 2

[0043] A method for manufacturing an ultra-high-strength and high-toughness Ti-6Al-4V alloy plate, the steps of which are as follows:

[0044] Step 1: high temperature solution treatment: the Ti-6Al-4V raw material is placed in a heat treatment furnace at 1030°C for 2 hours and cooled to room temperature;

[0045] Step 2: large deformation rolling: the material after the solution treatment in step 1 is subjected to large deformation rolling, and the large deformation rolling adopted is a large deformation warm rolling method. The material after the treatment in step 1 is subjected to two continuous warm rollings at 850° C. to obtain a plate;

[0046] Step 3: Ultrafine organization gradient heat treatment: The plate obtained in step 2 is subjected to gradient heat treatment organization control, and a high temperature short-time annealing + quenching + low temperature tempering method is adopted. The plate obtained in step 2 is placed in a heat treatment furnace, firstly subjected to high temperature annealing treatment at 1025°C for 10 minutes, and then subjected to low temperature tempering treatment at 150°C for 20 minutes after quenching, to obtain a Ti-6Al-4V alloy plate with an ultrafine organization structure.

[0047] The Ti-6Al-4V alloy plate prepared by the method of the present invention has a grain size of 280nm, is ultrafine grain, and has a uniform structure; a yield strength of 1250MPa, a tensile strength of 1355MPa, and a total elongation of 6.0%.

[0048] Example 3

[0049] A method for manufacturing an ultra-high-strength and high-toughness Ti-6Al-4V alloy plate, the steps of which are as follows:

[0050] Step 1 High temperature solution treatment: Place the Ti-6Al-4V raw material in a heat treatment furnace at 1020°C for 2.5 hours.

[0051] Cool to room temperature;

[0052] Step 2: large deformation rolling: the material after the solution treatment in step 1 is subjected to large deformation rolling processing, and the large deformation rolling adopted is large deformation warm rolling + cold rolling. The material after the treatment in step 1 is first subjected to two continuous warm rolling at 775° C. to obtain a warm-rolled plate, and then cooled to room temperature and subjected to two continuous rolling to obtain a plate;

[0053] Step 3: Ultrafine organization gradient heat treatment: The plate obtained in step 2 is subjected to gradient heat treatment organization control, and a low-temperature annealing + high-temperature short-time heat preservation + quenching method is adopted. The plate obtained in step 2 is placed in a heat treatment furnace, firstly subjected to low-temperature annealing treatment at 225°C for 8 minutes, and then subjected to high-temperature annealing treatment at 900°C for 25 minutes, and finally subjected to quenching to obtain a Ti-6Al-4V alloy plate with an ultrafine organization structure.

[0054] The Ti-6Al-4V alloy plate prepared by the method of the present invention has a grain size of 250nm, is ultrafine grain, and has a uniform structure; a yield strength of 1215MPa, a tensile strength of 1305MPa, and a total elongation of 8.0%.

[0055] Example 4

[0056] A method for manufacturing an ultra-high-strength and high-toughness Ti-6Al-4V alloy plate, the steps of which are as follows:

[0057] Step 1: high temperature solution treatment: the Ti-6Al-4V raw material is placed in a heat treatment furnace at 1045°C for 1 hour and cooled to room temperature;

[0058] Step 2: large deformation rolling: the material after the solution treatment in step 1 is subjected to large deformation rolling processing, and the large deformation rolling adopted is high temperature hot rolling + large deformation warm rolling + cold deformation. The material after the treatment in step 1 is first heated at 1025°C for 25 minutes, and then subjected to 3 passes of reversing hot rolling, with a final rolling temperature of 910°C to obtain a hot-rolled slab, and then cooled to 700°C for 2 passes of continuous warm rolling to obtain a warm-rolled plate, and finally cooled to room temperature for 2 passes of continuous rolling to obtain a plate;

[0059] Step 3: Ultrafine organization gradient heat treatment: The plate obtained in step 2 is subjected to gradient heat treatment organization control, and a low-temperature + medium-temperature short-time continuous annealing method is adopted. The plate obtained in step 2 is placed in a heat treatment furnace, firstly subjected to low-temperature annealing at 100°C for 30 minutes, and then subjected to medium-temperature annealing at 675°C for 5 minutes to obtain a Ti-6Al-4V alloy plate with an ultrafine organization structure.

[0060] The Ti-6Al-4V alloy plate prepared by the method of the invention has a grain size of 1150nm, is ultrafine grain, and has a uniform structure; a yield strength of 1400MPa, a tensile strength of 1600MPa, and a total elongation of 5.0%.

[0061] Embodiments 5 to 12

[0062] The processes and performances in the specific embodiments are shown in Table 1, which shows the processes and performances in the embodiments.

[0063] Among them, in step 2, large deformation rolling, embodiments 1, 5, and 9 adopt high-temperature hot rolling + large deformation warm rolling, embodiments 2, 6, and 10 adopt large deformation warm rolling, embodiments 3, 7, and 11 adopt large deformation warm rolling + cold rolling, and embodiments 4, 8, and 12 adopt high-temperature hot rolling + large deformation warm rolling + cold deformation.

[0064] In step 3, in the gradient heat treatment for microstructure ultrafineness, embodiments 1, 4, 7, and 10 adopt low temperature + medium temperature short-time continuous annealing, embodiments 2, 5, 8, and 11 adopt high temperature short-time annealing + quenching + low temperature tempering, and embodiments 3, 6, 9, and 12 adopt low temperature annealing + high temperature short-time insulation + quenching.

[0065]

[0066] Table 1

[0067] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate, characterized in that: The steps include: Step 1 High temperature solution treatment: The initial alloy is placed in (T β +20~T β +50)℃ heat treatment furnace for 1.0~3.0 hours, then cooled to room temperature, T β is the β phase transition temperature point; Step 2: large deformation rolling: the material after the solution treatment in step (1) is subjected to large deformation rolling processing, and the large deformation rolling adopted is any one of the four methods of high temperature hot rolling + large deformation warm rolling, large deformation warm rolling, large deformation warm rolling + cold rolling, high temperature hot rolling + large deformation warm rolling + cold rolling; Step 3: Ultrafine organization gradient heat treatment: The plate of step (2) is subjected to gradient heat treatment organization control, and any one of the three methods of low temperature + medium temperature short-time continuous annealing, high temperature short-time annealing + quenching + low temperature tempering, low temperature annealing + high temperature short-time insulation + quenching is adopted to obtain a Ti-6Al-4V alloy plate with an ultrafine organization structure.

2. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claim 1, characterized in that: The specific steps are as follows: In the high temperature solution treatment described in step 1, the initial alloy is a plate in a forged state, a hot rolled state, an annealed state or an aging treatment state; In the large deformation rolling described in step 2, the rolling method adopts large deformation asynchronous rolling or large deformation asynchronous rolling + synchronous rolling, the speed ratio of asynchronous rolling is 1.2 to 2.0, and the total rolling deformation is not less than 90%; In the ultra-fine organization gradient heat treatment described in step 3, the temperature of the low-temperature annealing treatment is not higher than 300°C, the temperature of the medium-temperature short-time heat treatment is 500-700°C, the temperature of the high-temperature short-time heat treatment is 850-1150°C, and the short-time insulation time is not higher than 30 minutes.

3. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claim 2, characterized in that: The specific steps are as follows: In the large deformation rolling described in step 2, high temperature hot rolling + large deformation warm rolling are adopted, wherein: the large deformation warm rolling adopts large deformation asynchronous rolling + synchronous rolling, and the total deformation is not less than 92%, and the final rolled plate thickness is 2.0 mm or less; In the ultra-fine organization gradient heat treatment described in step 3, a high temperature short-time annealing + quenching + low temperature tempering process is adopted. The high temperature short-time heat treatment temperature is 950-1050°C, the short-time holding time is not higher than 10 minutes, the low temperature annealing temperature is not higher than 300°C, and the holding time does not exceed 30 minutes.

4. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claim 3, characterized in that: The specific steps are as follows: In the large deformation rolling described in step 2, a large deformation asynchronous rolling + synchronous rolling method is adopted, the asynchronous rolling deformation is not less than 85%, the synchronous rolling deformation is not less than 10%, the total deformation is not less than 95%, and the final rolled plate thickness is 1.5 mm or less; In the ultra-fine organization gradient heat treatment described in step 3, a high temperature short-time annealing + quenching + low temperature tempering process is adopted, the high temperature short-time treatment temperature is 1000-1050°C, the short-time holding time is 2.0-5.0min, the low temperature annealing treatment is 250-300°C, and the holding time is 20-30min.

5. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claims 1 to 4, characterized in that: In step 1, in the high-temperature solution treatment, a stepwise gradient heating method is used, and T r ~(T β The heating rate from (T -200)℃ is 180~240℃ / h, (T β -200)℃ and the heating rate is 60~80℃ / h, where T r It is room temperature.

6. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy sheet according to claims 1 to 4, characterized in that: The large deformation asynchronous rolling used in step 2 is any one of the three methods: the roller diameters are the same but the rotation speeds are different, the roller diameters are different but the rotation speeds are the same, or the roller diameters and rotation speeds are different.

7. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claims 1 to 4, characterized in that: In step 2, in the large deformation rolling, the first pass is a single rolling along the width direction of the slab; the second pass is to rotate the slab 90° and roll it once along the length direction of the slab.

8. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claims 1 to 4, characterized in that: In step 2, the high-temperature hot rolling used in the large deformation rolling is heating at 950-1100°C for 20-30 minutes, and performing 3-6 passes of reversing hot rolling, with the final rolling temperature not lower than 900°C; the large deformation warm rolling is performing 2-3 continuous warm rolling passes at 700-850°C; and the cold rolling is performing 2 continuous rolling passes at room temperature.

9. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claims 1 to 4, characterized in that: After the treatment in step 2, Ti-6Al-4V is a typical β transformation structure, that is, an ultra-fine lamellar structure with thin layers of lamellar β phase distributed in the middle of the α layer, showing fine microscopic shear bands with an average size of 100 to 150 nm.

10. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claims 1 to 4, characterized in that: In step 3, in the gradient heat treatment for ultra-fine organization, a low-temperature + medium-temperature short-time continuous annealing process is adopted, and the final material organization maintains a lamellar structure, and a large number of dispersed nano-precipitates are distributed in the matrix of the lamellar organization.

11. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claims 1 to 4, characterized in that: In step 3, in the gradient heat treatment for ultrafine organization, a high temperature short-time annealing + quenching + low temperature tempering or a low temperature annealing + high temperature short-time insulation + quenching process is adopted. The high temperature short-time time is less than 10 minutes. The final material organization basically retains the macroscopic structural characteristics of the lamellar structure, that is, the α+β two-phase ultrafine lamellar organization structure and the dispersed nano-precipitation.

12. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claims 1 to 4, characterized in that: In step 3, in the gradient heat treatment for ultra-fine organization, a high temperature short-time annealing + quenching + low temperature tempering or a low temperature annealing + high temperature short-time insulation + quenching process is adopted. The high temperature short-time time exceeds 10 minutes. The final material organization is transformed into an ultra-fine equiaxed (α+β) phase and a hexagonal martensite α' phase dispersed in the β phase, with an average grain size of 150 to 400 nm.

13. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claim 1, characterized in that: The yield strength of the alloy plate shall not be less than 1000MPa, the tensile strength shall not be less than 1200MPa, and the total elongation shall not be less than 5.0%.

14. The method for manufacturing an ultra-high strength and high toughness Ti-6Al-4V alloy plate according to claim 1, characterized in that: The yield strength of the alloy plate with the ultrafine structure is not less than 1200 MPa, the tensile strength is not less than 1500 MPa, and the elongation is not less than 8.0%.

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