Preparation method of Ti2AlNb-based alloy plate

Abstract

The invention belongs to the technical field of titanium-based intermetallic compound processing, and particularly relates to a preparation method of a Ti2AlNb-based alloy plate, which comprises the following steps: preparing and drying Ti2AlNb-based alloy powder; a substrate is cleaned and pretreated, and the substrate is placed in a low-oxygen forming bin and preheated to 280-350 DEG C; a coaxial powder feeding type laser melting deposition process is adopted, and layer-by-layer deposition is carried out through 90-degree interlayer rotation and a layer-by-layer remelting mode; stress relief annealing is conducted on the part at 600-800 DEG C after deposition, and grinding and finishing are conducted; and finally, the ground blank is heated to 50-10 DEG C lower than the beta phase transformation point for reversing rolling, and the alloy plate is obtained after air cooling. The room-temperature tensile strength of the obtained plate is larger than or equal to 1080 MPa, the ductility is larger than or equal to 8%, the high-temperature yield strength at 750 DEG C and the high-temperature yield strength at 800 DEG C are not lower than 630 MPa and 450 MPa respectively, and the method is simple in technological process, high in material utilization rate and suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of titanium-based intermetallic compound processing, and particularly relates to a preparation method of Ti2AlNb-based alloy plate. BACKGROUND

[0002] The Ti2AlNb-based alloy plate can be applied to the skin, rudder and wing parts of aerospace vehicles due to excellent high-temperature yield strength, good high-temperature creep resistance and high oxidation resistance. The patent "Ti2AlNb alloy plate preparation method" (patent number: CN202010131495.7) prepares the Ti2AlNb alloy plate through the process of placing the blank in a cladding for sealing and then performing multi-pass rolling, but the rolling temperature is set in the B2 single-phase region, which is easy to form coarse beta / B2 grains and reduce the room temperature strength and plasticity of the alloy. The patent "Ti2AlNb alloy plate, preparation method and application thereof" (patent number: CN202211231724.8) adopts the process of Ti2AlNb pre-alloy powder hot isostatic pressing to prepare the blank and rolling, and cooperates with certain parameter conditions to prepare the Ti2AlNb alloy plate, but the temperature control in the hot isostatic pressing process is easy to cause the temperature difference between the edge and the center of the blank, resulting in uneven microstructure of the blank and performance fluctuation, and in addition, the size of the blank prepared by the hot isostatic pressing is limited. The patent "Preparation method of high-performance Ti2AlNb-based alloy plate" (patent number: CN202310346244.4) prepares the Ti2AlNb alloy plate through multi-directional near isothermal forging and hot rolling. In the blank preparation process, the 2-5mm thick 304 stainless steel is used to clamp the forging blank in the middle, and the four corners of the two 304 stainless steels are fixed by rivets to form the blank for hot rolling, but the rivet is usually different from the blank in material, which may contaminate the Ti2AlNb base body due to element diffusion at high temperature, or form a stress concentration point at the rivet hole to become the source of micro-cracks. It can be seen that the traditional preparation method of the Ti2AlNb-based alloy plate has the defects of poor microstructure uniformity, unstable performance and low material utilization, which is mainly caused by the difficulty in controlling the composition uniformity of the alloy, the intrinsic brittleness of the alloy, the large number of forming passes, the poor thermal conductivity and the significant element redistribution of each phase in the hot working process. SUMMARY

[0003] In order to solve the above technical problems, the application provides a preparation method of Ti2AlNb-based alloy plate. The microstructure of the plate after rolling is composed of fine alpha2 / O particles and beta / B2 matrix, and the size of the alpha2 / O particles is controlled to be less than 2 microns and is uniformly distributed. The prepared Ti2AlNb-based alloy plate has excellent strength and plasticity matching, and the mechanical properties of the plate in the transverse and longitudinal directions are isotropic, which meets the service requirements of the skin, rudder and wing parts of aerospace vehicles, solves the problem of deformation difficulty in the rolling process, has a simple process flow, high material utilization and is suitable for large-scale industrial production.

[0004] The specific technical solution is as follows: A method for preparing a Ti2AlNb-based alloy plate includes the following steps: Step 1: Prepare Ti2AlNb-based alloy powder, dry the powder and load it into a powder cylinder; Step 2: Sand the substrate with sandpaper to remove the oxide scale and wipe it clean with acetone. Then place the substrate into the molding chamber, seal it, and perform vacuum treatment to ensure that the oxygen content in the molding chamber is <50ppm. Step 3: Heat the substrate before laser melting deposition to maintain the substrate temperature at 280℃~350℃; Step 4: Layer-by-layer deposition is performed using a coaxial powder feeding laser melting deposition process. The printing path uses a multi-pass, multi-scan method. During each layer deposition process, the deposition direction between layers is rotated 90° relative to the previous layer. After each layer is deposited, it is remelted before the next layer is deposited. Step 5: Heat the deposited part to 600℃~800℃ and hold for 60min~180min for stress relief annealing, and then grind and finish the surface of the part. Step 6: Heat the ground parts to 10~20℃ below the β phase transformation point, heat through at a coefficient of 1min / mm, and then hold for 60~120min. After taking them out of the furnace, roll them to the target size using a reversing rolling method. After rolling, air cool to obtain hot-rolled Ti2AlNb-based alloy sheet.

[0005] The preferred embodiment of the method for preparing a Ti2AlNb-based alloy plate is that, in step 1, the Ti2AlNb-based alloy powder is a spherical powder with a particle size of 50~150μm.

[0006] The preferred embodiment of the method for preparing a Ti2AlNb-based alloy plate is as follows: in step 1, the obtained powder is placed in a vacuum drying oven for drying at a temperature of 80℃~100℃ for 8~10h.

[0007] The preferred embodiment of the method for preparing a Ti2AlNb-based alloy plate is that, in step 2, the substrate is a TA15 titanium alloy substrate.

[0008] The preferred embodiment of the method for preparing a Ti2AlNb-based alloy plate is as follows: in step 4, the laser melting deposition process parameters are: laser power 2600~3200 W, scanning speed 5mm / s~20mm / s, spot diameter 3mm~5mm, and laser power density 1.3×10⁻⁶. 4 W / cm 2 ~4.5×10 4W / cm 2 The laser melting deposition process has a small molten pool and a short solidification time, and elements cannot diffuse for a long distance, which can effectively avoid macrosegregation caused by large density difference between Al and Nb elements in the traditional Ti2AlNb ingot melting process, and is beneficial to improve the uniformity of alloy composition and structure.

[0009] The preferred scheme of the preparation method of the Ti2AlNb-based alloy plate is that, in step 4, the single-layer deposition thickness is 1-2 mm.

[0010] The preferred scheme of the preparation method of the Ti2AlNb-based alloy plate is that, in step 5, the cooling mode after the stress relief annealing treatment is air cooling.

[0011] The preferred scheme of the preparation method of the Ti2AlNb-based alloy plate is that, in step 6, the rolling deformation amount is 20%-50%.

[0012] The preferred scheme of the preparation method of the Ti2AlNb-based alloy plate is that, after the rolling in step 6, the obtained base alloy plate has a microstructure composed of fine α2 / O particles and a β / B2 matrix, wherein the size of the α2 / O particles is controlled to be below 2 μm and the α2 / O particles are uniformly distributed.

[0013] The preferred scheme of the preparation method of the Ti2AlNb-based alloy plate is that the Ti2AlNb-based alloy plate prepared by the method has a tensile strength at room temperature of not less than 1080 MPa, an elongation of not less than 8%, a high-temperature yield strength at 750 DEG C of not less than 630 MPa, a high-temperature yield strength at 800 DEG C of not less than 450 MPa, and no significant anisotropy in the mechanical properties in the transverse and longitudinal directions of the plate. Beneficial effects

[0014] The laser melting deposition process has a small molten pool and a short solidification time, and elements cannot diffuse for a long distance, which can effectively avoid macrosegregation caused by large density difference between Al and Nb elements in the traditional Ti2AlNb ingot melting process, and is beneficial to improve the uniformity of alloy composition and structure.

[0015] The laser melting deposition process has a small molten pool and a short solidification time, and elements cannot diffuse for a long distance, which can effectively avoid macrosegregation caused by large density difference between Al and Nb elements in the traditional Ti2AlNb ingot melting process, and is beneficial to improve the uniformity of alloy composition and structure.

[0016] The laser melting deposition process has a small molten pool and a short solidification time, and elements cannot diffuse for a long distance, which can effectively avoid macrosegregation caused by large density difference between Al and Nb elements in the traditional Ti2AlNb ingot melting process, and is beneficial to improve the uniformity of alloy composition and structure.

[0017] The second scanning with laser at the end of printing in each layer remelts the solid layer, which can eliminate defects such as pores, slag inclusions and cracks generated in the laser melting deposition process, reduce residual stress, and further improve the quality of the blank.

[0018] In the plate rolling process, by changing the rolling direction between each pass, the strong texture formed in a single direction can be weakened, the deformation uniformity of the grains can be improved, the performance of the material in the longitudinal and transverse directions can be more uniform and consistent, and the anisotropy of the material can be reduced.

[0019] The rolling is selected to be performed in the α2+B2 two-phase region, the soft B2 phase undertakes the main deformation, which is beneficial to the formability of the alloy, in addition, the fewer uniformly distributed hard α2 particles as the second phase can inhibit the growth of B2 grains during the deformation process, which is beneficial to the final organization regulation.

[0020] Compared with the traditional forging and multiple rolling forming, the Ti2AlNb-based alloy plate forming process by laser melting deposition and one-fire rolling can significantly reduce the process, improve the production efficiency, and avoid the problem of α2 / O particle growth caused by multiple deformation and rolling processes.

[0021] The microstructure of the Ti2AlNb-based alloy plate prepared by the method is composed of fine α2 / O particles and β / B2 matrix, wherein the size of the α2 / O particles is controlled to be less than 2 μm and is uniformly distributed. In terms of performance, the room temperature tensile strength is not less than 1080 MPa, the elongation is not less than 8%, the high temperature yield strength at 750°C is not less than 630 MPa, the high temperature yield strength at 800°C is not less than 450 MPa, the plate has no anisotropy in the longitudinal and transverse directions, and meets the service requirements of the skin, rudder wing and other components of the aerospace aircraft, which can solve the problem of poor uniformity of the traditional casting and rolling process of the Ti2AlNb alloy plate, has high material utilization, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a high magnification microstructure photograph of the Ti2AlNb alloy plate in Example 1; Figure 2 It is a high magnification microstructure photograph of the Ti2AlNb alloy plate in Example 2; Figure 3 It is a high magnification microstructure photograph of the Ti2AlNb alloy plate in Comparative Example 1; Figure 4 It is a high magnification microstructure photograph of the Ti2AlNb alloy plate in Comparative Example 2. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the following will combine the drawings of the embodiments of the present application with the specific embodiments of the present application. Figures 1-4The specific embodiments of the present application are described in detail. Those skilled in the art can make appropriate adjustments without departing from the spirit of the application. The following examples can further illustrate the present application, but not limit the present application in any form. The specific preparation method of the Ti2AlNb-based alloy plate is as follows: Example 1

[0024] The prepared Ti2AlNb chemical composition is Ti-21.9Al-24.1Nb-0.55Mo, and the T β The phase transition point is 1055℃, the plate size of TA15 alloy is 950mm×950mm×200mm, the chemical composition is Ti-6.5Al-2Zr-1Mo-1V, and the preparation method of the Ti2AlNb-based alloy plate is as follows: The specific preparation method of the Ti2AlNb-based alloy plate is as follows: Step 1: Prepare Ti2AlNb-based alloy powder, put the powder into a vacuum drying oven for drying, the drying temperature is 80℃, the drying time is 8h, and after drying, load into a powder cylinder; Step 2: Sand the base plate to remove the oxide skin and wipe it clean with acetone, then seal the base plate in the forming bin and perform vacuum treatment to make the oxygen content in the forming bin <50ppm; Step 3: Heat the base plate before laser melting deposition to 280℃; Step 4: Use coaxial powder feeding type laser melting deposition process for layer-by-layer deposition, the printing path uses multi-pass scanning mode, the deposition direction between layers is rotated by 90°, and after each layer is deposited, the next layer is deposited after remelting; The single-layer deposition thickness is 2mm, and the total size of the deposited alloy is X×Y×Z=860mm×780mm×24mm; The laser melting deposition process parameters are: laser power 2600W, scanning speed 5mm / s, spot diameter 3mm, laser power density 1.3×10 4 W / cm 2 , powder feeding rate 0.08g / s, overlap rate 40%, protective gas argon flow rate 10L / min; Single-layer deposition thickness is 1mm; Step 5: Heat the deposited and formed parts to 600℃ for 60min for stress relief annealing treatment, and then air cool after stress relief annealing treatment; Then grind and trim the surface of the Ti2AlNb-based alloy; Step 6: The ground part is heated to 1020℃ by using a resistance wire heating furnace, and is kept for 120 min before being taken out of the furnace. The part is rolled along the X direction to X×Y×Z=920mm×785mm×18mm, with a deformation of 25%. Then the part is rolled along the Y direction to X×Y×Z=930mm×815mm×14mm, with a deformation of 22.2%. After rolling, the part is air-cooled to obtain the hot-rolled alloy plate.

[0025] Table 1 Mechanical properties of the Ti2AlNb-based alloy plate prepared in Example 1

[0026] Conclusion: The microstructure of the plate prepared in Example 1 is composed of fine α2 / O particles and β / B2 matrix, and the average size of the α2 / O particles is 1.71 μm. The microstructure is shown in FIG. 1. The mechanical properties of the Ti2AlNb-based alloy plate prepared in this example after heat treatment are shown in Table 1. The mechanical properties along different directions at room temperature and high temperature are small, and the plate has a good match of high strength and high plasticity. Figure 1

[0027] Example 2

[0028] The prepared Ti2AlNb chemical composition is Ti-22.5Al-23.8Nb-0.48Mo, and the T β The phase transition point is 1060℃, the size of the TA15 alloy plate is 950mm×950mm×200mm, the chemical composition is Ti-6.5Al-2Zr-1Mo-1V, and the preparation method of the Ti2AlNb-based alloy plate is as follows. The specific preparation method of the Ti2AlNb-based alloy plate is as follows: Step 1: Prepare Ti2AlNb-based alloy powder, and dry the powder in a vacuum drying box at a temperature of 100℃ for 10h, and then load the powder into a powder cartridge; Step 2: The base plate is polished with sandpaper to remove the oxide skin and cleaned with acetone. The base plate is placed in the forming bin and sealed for vacuum treatment, so that the oxygen content in the forming bin is <50ppm; Step 3: Heat the base plate before laser melting deposition to 350℃; Step 4: Layer-by-layer deposition is performed by using a coaxial powder feeding type laser melting deposition process. The printing path adopts a multi-pass scanning mode. The deposition direction is rotated by 90° between layers during the deposition process. After each layer is deposited, the next layer is deposited after remelting. The single-layer deposition thickness is 2mm, and the total size of the deposited alloy is X×Y×Z=900mm×860mm×20mm; ​The laser melting deposition process parameters are as follows: laser power 2800W, scanning speed 20mm / s, laser power density 1.4x10 4 W / cm 2 , spot diameter 5mm, powder feeding rate 10g / min, overlap rate 40%, argon flow rate 15L / min; Step 5: the printed part is heated to 800℃ for 180min for stress relief annealing treatment, and then air-cooled after stress relief annealing treatment; then the Ti2AlNb-based alloy is ground and trimmed; Step 6: the ground and trimmed part is heated to 1030℃ by using a resistance wire heating furnace, and then heated for 120min and taken out of the furnace, and then rolled along the Y direction to XxYxZ=910mmx895mmx15mm, with a deformation of 25%; then rolled along the X direction to XxYxZ=955mmx900mmx12mm, with a deformation of 20%, and then air-cooled after rolling, to obtain a hot-rolled alloy plate.

[0029] Table 2 Mechanical properties of the Ti2AlNb-based alloy plate prepared in Example 2

[0030] Conclusion: The microstructure of the plate prepared in this example 2 is composed of fine α2 / O particles and β / B2 matrix, and the average size of the α2 / O particles is 1.57μm, and the microstructure is as shown in Figure 2 Table 2. The mechanical properties of the Ti2AlNb-based alloy plate prepared in this example after heat treatment are as shown in Table 2, and the mechanical properties along different directions at room temperature and high temperature are small, and have a good match of high strength and high plasticity.

[0031] Comparative Example 1 The prepared Ti2AlNb chemical composition is Ti-21.9Al-24.1Nb-0.55Mo, and the T β transformation point of the alloy is 1055℃, the size of the TA15 alloy plate is 900mmx900mmx180mm, the chemical composition is Ti-6.5Al-2Zr-1Mo-1V, and the preparation method of the Ti2AlNb-based alloy plate is as follows; The specific preparation method of the Ti2AlNb-based alloy plate is as follows: Step 1: prepare Ti2AlNb-based alloy powder, and then dry the powder and load it into a powder cylinder; Step 2: polish the substrate with sandpaper to remove the oxide skin and wipe it clean with acetone, then seal the forming bin after placing the substrate into it for vacuum treatment, so that the oxygen content in the forming bin is <50ppm; Step 3: heat the substrate before laser melting deposition to 300℃; Step 4: Layer-by-layer deposition is performed by using multi-pass and multi-time scanning mode, and the deposition process is not reversed between layers. After each layer is deposited and remelted, the next layer is deposited; the thickness of each layer is 2 mm, and the total size of the deposited alloy is XxYxZ = 850 mm x 850 mm x 25 mm; The laser melting deposition process parameters are as follows: laser power 2600 W, scanning speed 20 mm / s, laser power density 2.0 x 10 4 (W / cm 2 ), spot diameter 4 mm, powder feeding rate 10 g / min, overlap rate 40%, argon flow rate 15 L / min; Step 5: The printed part is heated to 600 DEG C for 60 min for stress relief annealing treatment, and the Ti2AlNb-based alloy after treatment is ground for trimming; Step 6: The trimmed part is heated to 1010 DEG C in a resistance wire heating furnace, and is kept for 120 min before being taken out of the furnace. It is rolled along the X direction to XxYxZ = 910 mm x 855 mm x 20 mm, with a deformation of 20%. It is continuously rolled along the X direction to XxYxZ = 965 mm x 860 mm x 16 mm, with a deformation of 20%. After rolling, it is air-cooled to obtain a hot-rolled alloy plate.

[0032] Table 3 Mechanical properties of the Ti2AlNb-based alloy plate prepared in Comparative Example 1

[0033] Conclusion: The microstructure of the plate prepared in Comparative Example 1 is composed of a2 / O particles and a β / B2 matrix. The a2 / O particles have poor spheroidization and large size, with an average size of 1.84 μm. The microstructure is shown in Figure 3 Table 3. The mechanical properties of the Ti2AlNb-based alloy plate prepared in the comparative example after heat treatment are shown in Table 3. The mechanical properties at room temperature and high temperature have large differences along different directions.

[0034] Comparative Example 2 The Ti2AlNb chemical composition prepared is Ti-22.5Al-23.8Nb-0.48Mo, and the T β transus point of the alloy is 1060 DEG C. The size of the TA15 alloy plate is 900 mm x 900 mm x 180 mm, and the chemical composition is Ti-6.5Al-2Zr-1Mo-1V. The preparation method of the Ti2AlNb-based alloy plate is as follows: The specific preparation method of the Ti2AlNb-based alloy plate is as follows: Step 1: Prepare Ti2AlNb-based alloy powder, and load the dried powder into a powder cylinder; Step 2: The substrate is polished with sandpaper to remove the oxide scale and cleaned with acetone, and then the substrate is placed into a forming bin and sealed for vacuum treatment, so that the oxygen content in the forming bin is less than 50 ppm; Step 3: The substrate is heated before laser melting deposition, and the heating temperature is 350 DEG C; Step 4: The laser melting deposition process is used, and the printing path is a multi-pass scanning mode for layer-by-layer deposition. The deposition direction between layers is rotated by 90 DEG during the deposition process, and after each layer is deposited, the next layer is deposited after remelting. The single-layer deposition thickness is 2 mm, and the total size of the deposited alloy is X*Y*Z = 860 mm*860 mm*20 mm; The laser melting deposition process parameters are as follows: laser power 3000 W, scanning speed 20 mm / s, laser power density 2.4*10 4 (W / cm 2 ), spot diameter 4 mm, powder feeding rate 10 g / min, overlap rate 40%, argon flow rate 15 L / min; Step 5: The printed part is heated to 800 DEG C and held for 180 min for stress relief annealing treatment, and the Ti2AlNb-based alloy after treatment is ground and trimmed; Step 6: The ground and trimmed part is heated to 1000 DEG C by using a resistance wire heating furnace, held for 120 min, and taken out of the furnace. The first pass is rolled along the Y direction to X*Y*Z = 865 mm*900 mm*15 mm, and the deformation amount is 25%. Without changing the rolling direction, the part is continuously rolled along the Y direction to X*Y*Z = 870 mm*935 mm*12 mm, and the deformation amount is 20%. After rolling, the part is air-cooled to obtain a hot-rolled alloy plate.

[0035] Table 4 Mechanical properties of the Ti2AlNb-based alloy plate prepared in Comparative Example 2

[0036] Conclusion: The microstructure of the plate prepared in Comparative Example 2 is composed of alpha2 / O particles and beta / B2 matrix, the alpha2 / O particles have poor spheroidization degree and large size, the average size is 3.14 microns, and the microstructure is shown in Figure 4 The mechanical properties of the Ti2AlNb-based alloy plate prepared in the comparative example after heat treatment are shown in Table 4, and the mechanical properties at room temperature and high temperature have large differences along different directions, and the overall performance is low.

[0037] The remaining matters of the present application are known technologies.

[0038] The above describes some embodiments of the present application, which are relatively specific. Within the technical concept of the present application, the technical solutions of the present application can be deformed in various ways. These all belong to the protection scope of the present application.

Claims

1. A method for preparing a Ti2AlNb-based alloy plate, characterized in that, Includes the following steps: Step 1: Prepare Ti2AlNb-based alloy powder, dry the powder and load it into a powder cylinder; Step 2: Polish the substrate to remove oxide scale and clean it. Then place the substrate into the molding chamber, seal it, and perform vacuum treatment to ensure that the oxygen content in the molding chamber is <50ppm. Step 3: Heat the substrate before laser melting deposition to maintain the substrate temperature at 280℃~350℃; Step 4: Layer-by-layer deposition is performed using a coaxial powder feeding laser melting deposition process. The printing path uses a multi-pass, multi-scan method. During each deposition process, the deposition direction between layers is rotated 90° relative to the previous layer. After each layer is deposited, it is remelted before the next layer is deposited. Step 5): Heat the deposited part to 600℃~800℃ and hold for 60min~180min for stress relief annealing, and then grind and finish the surface of the part. Step 6): Heat the ground parts to 10~50℃ below the β phase transformation point, heat through at a coefficient of 1min / mm, and then hold for 60~120min. After taking them out of the furnace, roll them to the target size using a reversing rolling method. After rolling, air cool them to obtain hot-rolled Ti2AlNb-based alloy plates.

2. The method for preparing a Ti2AlNb-based alloy plate according to claim 1, characterized in that: In step 1, the Ti2AlNb-based alloy powder is a spherical powder with a particle size range of 50~150μm.

3. The method for preparing a Ti2AlNb-based alloy plate according to claim 1, characterized in that: In step 1, the obtained powder is placed in a vacuum drying oven for drying at a temperature of 80℃~100℃ for 8~10 hours.

4. The method for preparing a Ti2AlNb-based alloy plate according to claim 1, characterized in that: In step 2, the substrate is a TA15 titanium alloy substrate.

5. A method for preparing a Ti2AlNb-based alloy plate according to claim 1, characterized in that: In step 4, the laser melting deposition process parameters are: laser power 2600~3200W, scanning speed 5mm / s~20mm / s, spot diameter 3mm~5mm, and laser power density 1.3×10⁻⁶. 4 W / cm 2 ~4.5×10 4 W / cm 2 The powder feeding rate is 0.08 g / s to 0.17 g / s, the overlap rate is 40% to 60%, and the protective gas argon flow rate is 10 L / min to 15 L / min.

6. A method for preparing a Ti2AlNb-based alloy plate according to claim 1, characterized in that: In step 4, the thickness of a single layer deposition is 1~2 mm.

7. A method for preparing a Ti2AlNb-based alloy plate according to claim 1, characterized in that: In step 5, the cooling method after the stress-relief annealing treatment is air cooling.

8. A method for preparing a Ti2AlNb-based alloy plate according to claim 1, characterized in that: In step 6, the rolling deformation is 20% to 50%.

9. A method for preparing a Ti2AlNb-based alloy plate according to claim 1, characterized in that: The base alloy sheet obtained after rolling in step 6 has a microstructure composed of fine α2 / O particles and β / B2 matrix, wherein the size of the α2 / O particles is controlled below 2μm and is uniformly distributed.

10. A method for preparing a Ti2AlNb-based alloy plate according to claim 1, characterized in that: The Ti2AlNb-based alloy plates prepared by this method have a room temperature tensile strength of not less than 1080 MPa and an elongation of not less than 8%; a high temperature yield strength of not less than 630 MPa at 750℃ and a high temperature yield strength of not less than 450 MPa at 800℃, and the plates have no significant anisotropy in transverse and longitudinal mechanical properties.

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