A Ti2AlNb alloy plate and its preparation process

Abstract

The application relates to the metal rolling technical field, and provides a Ti2AlNb alloy plate and a preparation process thereof, which comprises the following steps: performing open-die forging on a Ti2AlNb alloy ingot to obtain a forged blank; performing plate blank forging on the forged blank to obtain a plate blank; the plate blank forging comprises the following steps: upsetting at a temperature below a B2 phase transition point, and then elongating at a temperature above the B2 phase transition point; performing rolling treatment on the plate blank to obtain a plate; the rolling treatment comprises a reversing rolling process and a tandem rolling process, the reversing rolling process comprises first rolling in a first direction and second rolling in a second direction, and the second direction is perpendicular to the first direction; the tandem rolling process comprises cutting, stacking and sheathing the plate, and then rolling. The application effectively refines the grains, improves the uniformity of the structure, weakens the anisotropy of the plate, solves the thin plate rolling cracking problem, the prepared plate has good strength-plasticity matching, and is suitable for industrial production.

Description

Technical Field

[0001] This application relates to the field of metal rolling technology, specifically to a Ti2AlNb alloy sheet and its preparation process. Background Technology

[0002] Ti2AlNb alloy belongs to the Ti-Al-Nb alloy system and is mainly composed of the B2 phase (ordered β phase), α2 phase (Ti3Al), and O phase (Ti2AlNb). Among them, the orthorhombic phase (O phase) is the main strengthening phase, possessing high specific strength, good creep resistance, and oxidation resistance. It can maintain excellent performance for a long time between 650 and 750℃, and its short-term service temperature can reach 1000℃. It is an ideal replacement material for nickel-based superalloys in the aerospace field, which can significantly reduce structural weight and meet the development requirements of lightweight aerospace vehicles.

[0003] However, due to the poor room temperature plasticity, high deformation resistance, and narrow hot working window of Ti2AlNb alloy, coupled with the rapid temperature drop during rolling, the preparation of Ti2AlNb alloy plates is difficult. Cracking and edge cracking are prone to occur during rolling, resulting in low yield, low production efficiency, and high costs. Existing technologies typically employ single-phase forging or conventional rolling processes, which are insufficient to effectively improve the compositional segregation and microstructure inhomogeneity of the ingot. Furthermore, unidirectional large deformation rolling during plate rolling easily leads to significant anisotropy in the plate, resulting in large differences in transverse and longitudinal mechanical properties, making it difficult to meet the stringent isotropic requirements of materials for critical structural components such as aerospace vehicle skins and rudders. In addition, for thin plates, rapid heat dissipation and drastic temperature drops make cracking highly likely during rolling, and existing processes struggle to achieve stable production of high-quality thin plates. Summary of the Invention

[0004] To address the technical problems of easy cracking, poor microstructure uniformity, and significant anisotropy in the preparation of Ti2AlNb alloy plates in existing technologies, this application proposes a Ti2AlNb alloy plate and its preparation process. By adopting a synergistic control strategy of phase transformation point crossing deformation in the forging stage and reversal and stacking combination in the rolling stage, the plate microstructure uniformity and isotropy are improved, thus solving the problem of cracking in thin plates.

[0005] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, this application provides a process for preparing Ti2AlNb alloy sheet, comprising the following steps: forging a Ti2AlNb alloy ingot to obtain a forged billet; forging the forged billet into a slab to obtain a slab; the slab forging includes: upsetting at a temperature below the B2 phase transformation point (i.e., the critical temperature for the transformation of ordered β phase to α2 and O phases), followed by elongation at a temperature above the B2 phase transformation point; rolling the slab to obtain a sheet; the rolling process includes a reversing rolling process and a stacking rolling process, the reversing rolling process including a first rolling along a first direction and a second rolling along a second direction, the second direction being perpendicular to the first direction; the stacking rolling process includes cutting, stacking, and wrapping the sheet before rolling.

[0006] The above scheme effectively refines grains and improves microstructure uniformity by using a phase transformation point crossing deformation method of low-temperature upsetting below the B2 phase transformation point and high-temperature elongation above the B2 phase transformation point during the forging stage, taking advantage of the differences in plastic deformation mechanisms in different phase regions. In the rolling stage, the anisotropy caused by unidirectional large deformation is weakened by reversing rolling, and the problem of rapid temperature drop and easy cracking of thin plates is solved by stack rolling. Finally, Ti2AlNb alloy plates with uniform microstructure, low anisotropy, and good strength-plasticity matching are obtained.

[0007] As an optional implementation, the forging process includes: heating the Ti2AlNb alloy ingot to a temperature above the B2 phase transformation point, and performing upsetting and drawing at least three times.

[0008] The above scheme effectively breaks down the as-cast structure, promotes element diffusion, and improves the uniformity of the forged billet structure through high-temperature, large-deformation forging.

[0009] As an optional implementation, in the slab forging: the upsetting temperature is in the range of 50°C to 100°C below the B2 phase transformation point; the drawing temperature is in the range of 30°C to 55°C above the B2 phase transformation point.

[0010] The above scheme ensures coordinated deformation of the forging billet in the two-phase and single-phase regions by precisely controlling the temperature window for upsetting and drawing, thus avoiding the risk of overheating due to excessively high temperature or cracking due to excessively low temperature.

[0011] As an optional implementation, in the slab forging, the upsetting deformation is 40%~50%, and the upsetting deformation rate is 0.02s. - ¹~0.035s - ¹.

[0012] The above scheme optimizes the dynamic recrystallization behavior during slab forging by controlling the amount and rate of deformation, thereby improving the microstructure refinement effect.

[0013] As an optional implementation, in the slab forging: the final forging temperature of upsetting is not lower than 750°C; the final forging temperature of drawing is not lower than 850°C; and the forging direction is shaft upsetting and side drawing.

[0014] The above scheme avoids cracks caused by low-temperature forging by controlling the final forging temperature; the deformation direction of the shaft upset and side drawing is conducive to breaking dendrites and improving forging penetration.

[0015] As an alternative implementation, after the slab forging and before the rolling process, a slab forming step is further included: heating the slab to a temperature below the B2 phase transformation point and performing one or two upsetting and drawing operations.

[0016] The above solution improves the shape and dimensional accuracy of the slab through the slab forming step, providing a high-quality forging blank for subsequent rolling.

[0017] As an optional implementation, the final rolling temperature of the first rolling process is not lower than 800°C; the final rolling temperature of the second rolling process is not lower than 800°C.

[0018] The above scheme ensures that the slab is in a good plastic state during the rolling process by controlling the final rolling temperature, thus avoiding edge cracks and surface defects caused by low-temperature rolling.

[0019] As an optional implementation, the first rolling process is unidirectional rolling, with a per-pass deformation rate of 60%~75%, a per-pass deformation rate of 15%~20%, 4~6 passes, and a rolling speed of 1m / s~4m / s.

[0020] The above solution achieves rapid thinning of the slab by optimizing the process parameters of the first rolling, while ensuring the surface quality and internal structure of the plate.

[0021] As an optional implementation, the second rolling process is unidirectional rolling, with a per-pass deformation rate of 60%~75%, a per-pass deformation rate of 15%~20%, 4~6 passes, and a rolling speed of 1m / s~4m / s.

[0022] The above scheme effectively weakens the anisotropy of the sheet by optimizing the process parameters of the second rolling process and making them perpendicular to the first rolling direction.

[0023] As an optional implementation, the rolling process further includes a third rolling step, which is located after the reversing rolling step and before the stacking rolling step. The rolling direction of the third rolling step is consistent with the second direction, and the final rolling temperature of the third rolling step is not lower than 800°C.

[0024] The above solution reduces the thickness of the sheet by adding a third rolling process, providing a suitable forging billet size for subsequent stacking rolling.

[0025] As an optional implementation, the deformation rate of the third rolling process is 60%~75%, the deformation rate per pass is 5%~10%, the number of passes is 6~8, and the rolling speed is 1m / s~2m / s.

[0026] The above scheme precisely controls the thickness and surface quality of the sheet metal by using a precision rolling process with small deformation and multiple passes.

[0027] As an optional implementation, in the stacking process, the sheet metal is cut into two or three slabs of the same size, coated with a release coating on the contact surfaces, stacked, and then encased and welded with steel plates and edge strips.

[0028] The above-mentioned scheme effectively prevents the adhesion between the plates during the stacking process through pretreatment before stacking and ensures the integrity of the stacked blank, which facilitates the rolling operation.

[0029] As an optional implementation, the heating temperature of the stacking process is 10°C to 30°C below the B2 phase transformation point, the rolling method is single-pass forming, and the final rolling temperature is not lower than 900°C.

[0030] The above scheme achieves one-time forming of thin plates by performing single-pass large deformation stacking in the α2+B2 two-phase region and using the hard α2 phase to suppress the growth of B2 grains, thus avoiding the microstructure deterioration caused by multiple heating.

[0031] As an optional implementation, the plate is further subjected to heat treatment, which includes solution treatment and aging treatment; the solution treatment temperature is 960℃~980℃, the time is 2h, and the cooling method is oil cooling or air cooling; the aging treatment temperature is 780℃~820℃, the time is 24h, and the cooling method is air cooling.

[0032] The above scheme, through solution treatment and aging, yielded a three-phase microstructure consisting of equiaxed α2 / O particles, coarse lath α2 / O phase, and metastable B2 phase, achieving a good synergy between strength and plasticity.

[0033] Secondly, this application provides a Ti2AlNb alloy plate, which is prepared by the Ti2AlNb alloy plate preparation process described in any of the above claims.

[0034] The above-mentioned scheme ensures that Ti2AlNb alloy plates have excellent microstructure uniformity and mechanical properties by limiting the product through process.

[0035] As an optional embodiment, the thickness of the Ti2AlNb alloy plate is 1mm~5mm; the microstructure of the Ti2AlNb alloy plate is a three-state structure composed of equiaxed α2 / O particles, coarse lath α2 / O phase and metastable B2 phase, wherein the α2 / O particles are fine and uniformly distributed; the room temperature tensile strength of the Ti2AlNb alloy plate is greater than 1000MPa and the elongation is greater than 8%, the high temperature tensile strength at 750℃ is greater than 750MPa and the elongation is greater than 12%, and the difference between the transverse and longitudinal tensile strengths does not exceed 50MPa.

[0036] The above scheme clarifies the specifications, microstructure characteristics and mechanical properties of Ti2AlNb alloy plates, meeting the service requirements of structural components such as aerospace vehicle skins and rudders.

[0037] Compared with the prior art, the technical solution provided in this application has the following beneficial effects: This application provides a preparation process for Ti2AlNb alloy plates. Through low-temperature upsetting and high-temperature drawing in the forging stage, the phase transformation point is crossed by deformation, effectively refining the grains and improving the uniformity of the microstructure. Through reversible rolling in the rolling stage, the anisotropy of the plate is significantly weakened, controlling the difference in tensile strength between the transverse and longitudinal directions to within 50 MPa. The stack rolling process solves the problem of rapid temperature drop and easy cracking in thin plate rolling, achieving high-quality preparation of 1-5 mm thin plates. The resulting Ti2AlNb alloy plate has a microstructure composed of fine equiaxed α2 / O particles, coarse lath α2 / O phase, and metastable B2 phase. It exhibits a room temperature tensile strength greater than 1000 MPa and an elongation greater than 8%, a 750℃ high-temperature tensile strength greater than 750 MPa and an elongation greater than 12%, demonstrating good strength-plasticity matching, high production efficiency, and suitability for large-scale industrial production. Specific advantages are as follows: 1. The ingot casting process combines ultra-high temperature long-term heat preservation and multiple large deformation upsetting and drawing, which can effectively promote element diffusion and improve the uniformity of the microstructure.

[0038] 2. The forging billet is upsetting and drawing multiple times below the B2 phase region before forming the slab, which helps to improve the uniformity and formability of the slab structure, reduce the tendency of edge cracking and chipping caused by subsequent rolling, and greatly improve the stability of the plate rolling process.

[0039] 3. Strictly control the deformation amount and rate of forgings and slabs below the B2 phase region to effectively avoid overheating of forgings and improve microstructure uniformity. Simultaneously, this improves the surface quality of forgings, reduces machining losses, and increases yield.

[0040] 4. The rolling process employs two reversing rolling operations, which can mitigate the anisotropy problem caused by unidirectional large deformation rolling. At the same time, the reheating process in the furnace during rolling ensures the smooth progress of the process and significantly improves production efficiency.

[0041] 5. In the α2+B2 two-phase region, the cladding and rolling process is used in one-pass forming. On the one hand, the hard α2 phase and the plastic B2 phase can coexist, and the alloy has good formability. One-pass forming avoids the deterioration of the microstructure caused by heat treatment in the furnace. On the other hand, as the second phase, the α2 particles can inhibit the growth of B2 grains during the deformation process, so as to balance the strength and plasticity of the material.

[0042] 6. Controlling the rolling temperature below the solution treatment temperature is beneficial for subsequent heat treatment, microstructure, and property regulation of the sheet metal. The microstructure of the Ti2AlNb alloy sheet metal prepared in this application consists of equiaxed α2 / O particles, lath α2 / O phase, and metastable B2 phase, with the α2 / O particles uniformly distributed in the β / B2 matrix. After heat treatment, the sheet metal exhibits good strength-ductility matching, with a room temperature tensile strength greater than 1000 MPa and an elongation greater than 8%, and a high-temperature tensile strength greater than 750 MPa and an elongation greater than 12% at 750℃. The difference between the transverse and longitudinal tensile strengths of the sheet metal does not exceed 50 MPa, meeting the service requirements of structural components such as aerospace vehicle skins and rudders. It boasts high production efficiency and is suitable for large-scale industrial production. Attached Figure Description

[0043] Figure 1 This is a 1000x SEM image of the microstructure of the Ti2AlNb alloy plate from Example 1.

[0044] Figure 2 This is a 1000x SEM image of the microstructure of the Ti2AlNb alloy plate from Example 2. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0047] This application provides a process for preparing Ti2AlNb alloy sheet, mainly including the following steps: 1) Heating the Ti2AlNb alloy ingot to 140~200℃ above the B2 phase transformation point and completing at least three upsetting and three drawing forgings; 2) Heating the forging billet to 100~50℃ below the B2 phase transformation point for upsetting, then returning it to the furnace and heating it to 30~55℃ above the B2 phase transformation point for drawing; 3) Heating the forging billet to 100~50℃ below the B2 phase transformation point and completing one to two upsetting and drawing forgings to form a slab; 4) Heating the slab and rolling it in one heat to obtain a first-heat slab; 5) Rolling it in a second heat with reverse direction to obtain a second-heat slab; 6) Rolling it in a third heat to obtain a third-heat slab; 7) Cutting the third-heat slab, covering and rolling it in a fourth heat, and then straightening it to obtain the Ti2AlNb alloy sheet. The specific steps are as follows: Step 1: Heat the Ti2AlNb alloy ingot to 140~200℃ above the B2 phase transformation point, complete no less than three upsetting and three drawing forgings, with upsetting deformation of 50%~60%, and final forging temperature of no less than 850℃, followed by air cooling.

[0048] Specifically, the holding time of Ti2AlNb alloy ingots above the B2 phase transformation point shall not be less than 24 hours.

[0049] Step 2: Heat the forging billet to 100~50℃ below the B2 phase transformation point for upsetting, requiring upsetting deformation of 40%~50%, and the final forging temperature not lower than 750℃. Then, return the forging billet to the furnace and heat it to 30~55℃ above the B2 phase transformation point for elongation forging, with the final forging temperature not lower than 850℃, and air cool after forging.

[0050] Specifically, the forging billet adopts a low-temperature slow upsetting followed by high-temperature reversing drawing forging method. The forging direction is shaft upsetting and side drawing, the upsetting deformation is 40%~50%, and the upsetting deformation rate is 0.02s. -1 ~0.035s -1 .

[0051] Furthermore, this application employs a deformation direction control strategy of axial upsetting and side drawing. Specifically, axial upsetting and side drawing refers to a deformation method in which the material is upset along the axial direction and then elongated along a side perpendicular to the axial direction. This deformation method with changing direction allows the material to be subjected to compressive and tensile stresses in different directions, effectively breaking the dendrites in the core of the forging blank, improving forging penetration, and thus obtaining a slab with a more uniform microstructure.

[0052] Step 3: Heat the forging billet to 100~50℃ below the B2 phase transformation point, and complete 1~2 upsetting and drawing forgings. The upsetting deformation should be 40%~50%, the single deformation of the billet forming should be 15%~25%, and the final forging temperature should not be lower than 750℃. After forging, air cool. Specifically, the forging direction of the billet is shaft upsetting and side drawing, the upsetting deformation is 40%~50%, and the upsetting deformation rate and billet formation rate are 0.02s.-1 ~0.035s -1 The slab thickness is 100mm~120mm.

[0053] Step 4: Apply a high-temperature resistant antioxidant coating to the slab obtained in Step 3, wait for it to dry completely, and then put it into an electric heating roller hearth furnace. Heat the furnace to 100~50℃ below the B2 phase transformation point and perform one-fire rolling to obtain a one-fire slab.

[0054] Specifically, the rolling method is unidirectional rolling, the deformation rate per pass is 60%~75%, the final rolling temperature is not lower than 800℃, the deformation rate per pass is 15%~20%, the number of passes is 4~6, and the rolling speed is 1m / s~4m / s.

[0055] Step 5: The first-fired slab obtained in Step 4 is ground and coated with a high-temperature anti-oxidation coating. After it dries, it is placed in an electric heating roller hearth furnace and heated to 100~50℃ below the B2 phase transformation point for second-fired rolling to obtain a second-fired slab.

[0056] Specifically, step 5 is a unidirectional rolling process, with the rolling direction perpendicular to the rolling direction of step 4. The deformation rate per pass is 60%~75%, the final rolling temperature is not lower than 800℃, the deformation rate per pass is 15%~20%, the number of passes is 4~6, and the rolling speed is 1m / s~4m / s.

[0057] Step 6: The slab obtained in Step 5 is ground and coated with a high-temperature anti-oxidation coating. After it dries, it is placed in an electric heating roller hearth furnace and heated to 100~50℃ below the B2 phase transformation point for three-fire rolling to obtain a slab.

[0058] Specifically, step 6 is a unidirectional rolling process, with the rolling direction being the same as that in step 5. The deformation rate per pass is 60% to 75%, the final rolling temperature is not lower than 800℃, the deformation rate per pass is 5% to 10%, the number of passes is 6 to 8, and the rolling speed is 1 m / s to 2 m / s.

[0059] Step 7: After surface treatment of the three-fired slab obtained in Step 6, cut it into 2-3 slabs of the same size. Stack the 2-3 three-fired slabs, apply a protective coating to the contact surfaces, and weld them together with steel plates, edge strips, etc. Then, load the wrapped and rolled slabs into an electric heating roller hearth furnace, heat them to 10-30°C below the B2 phase transformation point, and perform four-fire rolling. After straightening at 900°C-950°C, the plate is obtained.

[0060] Specifically, in step 7, the sheet material is cut along the width of the slab obtained in step 6. The rolling method is unidirectional rolling, with the rolling direction perpendicular to the rolling direction of step 6. The deformation rate per pass is 25%~50%, and it is a one-pass forming process. The final rolling temperature is not lower than 900℃, and the rolling speed is 1m / s~2m / s.

[0061] Furthermore, in steps 1-7, the forging billets are heated in the furnace, with the charging temperature not exceeding 700℃ and the heating rate not exceeding 5℃ / min. Steps 2-3: The holding time for cold material charging is 1D~(1D+90) min, and the holding time for hot material returning to the furnace is 0.4D~(0.4D+30) min, where D is the thickness of the minimum cross-section of the forging billet. Steps 4-7: The holding time for cold material charging is 1d~(1d+30) min, and the holding time for hot material returning to the furnace is 0.4d~(0.4d+10) min, where d is the slab thickness.

[0062] The thickness of the Ti2AlNb alloy plate is 1~5mm.

[0063] The heat treatment process for Ti2AlNb alloy sheets is: 960~980℃ / 2h / OC (rapid cooling) + 780~820℃ / 24h / AC (slow cooling). After solution treatment and aging, the Ti2AlNb alloy sheets exhibit excellent properties with a good balance of strength and plasticity. The room temperature tensile strength is greater than 1000MPa with an elongation greater than 8%, and the high-temperature tensile strength at 750℃ is greater than 750MPa with an elongation greater than 12%. The difference between the transverse and longitudinal tensile strengths of the sheets does not exceed 50MPa, meeting the service requirements of aerospace vehicle skins, rudders, and other structural components. The process is highly efficient and suitable for large-scale industrial production.

[0064] The microstructure of the Ti2AlNb alloy sheet prepared by this process consists of fine α2 / O particles, lath α2 / O phase, and metastable B2 phase, achieving a synergistic improvement in strength and plasticity. The difference between the transverse and longitudinal tensile strength of the sheet does not exceed 50 MPa, meeting the service requirements of structural components such as aerospace vehicle skin and rudders. It has high production efficiency and is suitable for large-scale industrial production.

[0065] The preparation process of Ti2AlNb alloy plate disclosed in this application is based on the following principle: (1) Forging across phase transformation point: Low-temperature slow upsetting is performed below the B2 phase transformation point (α2+B2 two-phase region), where hard α2 phase particles pin the grain boundaries and promote dynamic recrystallization, significantly refining the grains; then, high-temperature elongation is performed above the B2 phase transformation point (B2 single-phase region), utilizing the excellent plastic healing of early microcracks in the single-phase region. This path of first refining the grains and then healing solves the problem of coarse grains or cracking caused by forging in the single-phase region.

[0066] (2) Reversing rolling: Large deformation rolling is carried out in two mutually perpendicular directions to disrupt the strong base surface texture formed by unidirectional rolling, so that the mechanical properties of the plate in the transverse and longitudinal directions tend to be consistent, and the difference in transverse and longitudinal strength is controlled within 50MPa.

[0067] (3) Stacking and forming: Single-pass cladding and stacking is carried out in the α2+B2 two-phase region. On the one hand, the temperature drop is slowed down by increasing the total thickness of the forging billet, and on the other hand, the hard α2 phase is used to suppress the growth of B2 grains, so as to realize the thin plate forming in one step and avoid the deterioration of the structure caused by multiple heating.

[0068] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. The following embodiments illustrate this application in more detail, but do not limit this application in any way.

[0069] Example 1: The nominal composition (atomic fraction, at.%) of the Ti2AlNb alloy ingot used in this embodiment is Ti-22Al-23Nb-0.5Mo, with the balance being Ti. The B2 phase transformation point of this alloy ingot was determined to be 1060℃ using metallographic methods. Based on the above composition system and phase transformation temperature characteristics, this embodiment focuses on a multi-stage hot forging-multi-heat hot rolling-coating and stacking rolling-solution aging treatment within the B2 single-phase region and its adjacent phase transformation temperature region to achieve progressively thinner sheet metal, homogenized microstructure, and stable properties. The specific preparation process is as follows: Step 1: Heat the Ti2AlNb alloy ingot to 1200℃, hold for 600min, and raise the temperature at a rate of 5℃ / min to complete the three-upsetting and three-drawing forging. The upsetting deformation is 50%, the final forging temperature is 855℃, and the forging is air-cooled to obtain a forging billet with a thickness of 280mm.

[0070] Step 2: Heat the forging billet to 960℃, hold for 400 min, with a heating rate of 5℃ / min, and perform upsetting. The forging direction is shaft upsetting and side drawing, and the upsetting deformation rate is 0.02s. -1 The upsetting deformation is 40%, the final forging temperature is 755℃, and then the forging billet is returned to the furnace and heated to 1090℃ for elongation forging. The final forging temperature is 860℃, and after forging, it is air-cooled to obtain a slab with a thickness of 135mm.

[0071] Step 3: Heat the forging billet to 960℃ and hold for 300 minutes at a heating rate of 5℃ / min. Complete one upsetting and one drawing forging cycle. The upsetting deformation is 40%, the single-cycle deformation of the billet is 15%, and the upsetting deformation rate and billet formation rate are both 0.02s. -1 The final forging temperature was 755℃, and the slab with a thickness of 112mm was obtained by air cooling after forging. Step 4: Apply a high-temperature resistant, antioxidant coating to the slab obtained in Step 3, wait for it to dry completely, and then place it into an electrically heated roller hearth furnace. Heat the furnace to 960℃ and hold for 280 minutes at a heating rate of 5℃ / min. Perform single-pass rolling in unidirectional rolling, completed in 4 passes. The deformation rates of each pass are 16.3%, 18.8%, 17.1%, and 18.8%, respectively. The total deformation rate of the single-pass rolling is 60%. The final rolling temperature is 805℃, and the rolling speed is 4m / s, resulting in a single-pass slab with a thickness of 45mm.

[0072] Step 5: The first-fired slab obtained in Step 4 is surface-polished and coated with a high-temperature anti-oxidation coating. After drying, it is placed in an electrically heated roller hearth furnace and heated to 960℃ with the furnace. It is held at that temperature for 80 minutes, with a heating rate of 5℃ / min, and then subjected to second-fire rolling. The rolling method is unidirectional rolling, with the rolling direction perpendicular to the rolling direction in Step 4. The rolling is completed in 4 passes, with the deformation rates of each pass being 17.1%, 18.2%, 18.6%, and 17.9%, respectively. The total deformation rate of the first-fired slab is 60%. The final rolling temperature is 800℃, and the rolling speed is 4m / s, resulting in a second-fired slab with a thickness of 18mm.

[0073] Step 6: The slab obtained in Step 5 after two-fire rolling is surface-polished and coated with a high-temperature anti-oxidation coating. After drying, it is placed in an electrically heated roller hearth furnace and heated to 960℃ with the furnace. It is held at that temperature for 30 minutes at a heating rate of 5℃ / min and then rolled in three passes. The rolling method is unidirectional rolling, and the rolling direction is consistent with the rolling direction in Step 5. The rolling is completed in 6 passes. The deformation rates of each pass are 8.0%, 6.9%, 7.6%, 8.1%, 6.6%, and 7.9%, respectively. The total deformation rate is 60%. The final rolling temperature is 810℃, and the rolling speed is 2m / s, resulting in a slab with a thickness of 7mm.

[0074] Step 7: After surface treatment of the three-fired slab obtained in Step 6, cut it into three slabs of the same size. Stack the three three-fired slabs, apply a release coating to the contact surfaces, and weld them together using steel plates and edge strips. Then, load the coated stacked slabs into an electric heating roller hearth furnace, heat them to 1030℃, hold for 10 minutes at a heating rate of 5℃ / min, and perform four-fire rolling. The rolling method is unidirectional rolling, with the rolling direction perpendicular to the rolling direction in Step 6. The deformation rate per fire is 25%, and the slab is formed in one pass. The final rolling temperature is 905℃, and the rolling speed is 2m / s. After straightening at 900℃, a 5mm four-fired slab is obtained.

[0075] The isolation coating can be selected according to the needs, such as alumina suspension, yttrium oxide coating, glass lubricant, etc.

[0076] Step 8: Perform solution treatment and aging on the four-fired slab obtained in Step 7 to obtain a slab with uniform structure, stable performance, and a thickness of 5mm; Solution treatment regime: 960℃ / 2h / OC, Aging regime: 820℃ / 24h / AC.

[0077] Example 2: The nominal composition (atomic fraction, at.%) of the Ti2AlNb alloy ingot used in this embodiment is Ti-22Al-24Nb-0.5Mo, with the balance being Ti. The B2 phase transformation point of this alloy ingot was determined to be 1055℃ using metallographic methods. Based on the above composition system and phase transformation temperature characteristics, this embodiment focuses on a multi-stage hot forging-multi-heat hot rolling-coating and stacking rolling-solution aging treatment within the B2 single-phase region and its adjacent phase transformation temperature region to achieve progressively thinner sheet metal, homogenized microstructure, and stable properties. The specific preparation process is as follows: Step 1: Heat the Ti2AlNb alloy ingot to 1255℃, hold for 600 min, and raise the temperature at a rate of 5℃ / min to complete the three upsetting and three drawing forging. The upsetting deformation is 60%, the final forging temperature is 850℃, and the forging is air-cooled to obtain a forging billet with a thickness of 300mm.

[0078] Step 2: Heat the forging billet to 1005℃, hold for 300 min, with a heating rate of 5℃ / min, and perform upsetting. The forging direction is shaft upsetting and side drawing, and the upsetting deformation rate is 0.03s. -1 The upsetting deformation is 50%, the final forging temperature is 760℃, and then the forging billet is returned to the furnace and heated to 1110℃ for elongation forging. The final forging temperature is 855℃, and after forging, it is air-cooled to obtain a slab with a thickness of 160mm.

[0079] Step 3: Heat the forging billet to 1005℃ and hold for 120 minutes at a heating rate of 5℃ / min. Complete two forging cycles of upsetting and drawing. The upsetting deformation is 50%, and the single-cycle deformation of the billet is 25%. The upsetting deformation rate and the billet formation rate are both 0.03s. -1 The final forging temperature is 750℃, and the slab with a thickness of 120mm is obtained by air cooling after forging. Step 4: Apply a high-temperature resistant, antioxidant coating to the slab obtained in Step 3, allow it to dry completely, and then place it into an electrically heated roller hearth furnace. Heat the furnace to 1005℃ and hold for 120 minutes at a heating rate of 5℃ / min. Perform a single-pass rolling process using unidirectional rolling, completed in 6 passes. The deformation rates for each pass are 18.2%, 18.8%, 19.2%, 18.4%, 19.1%, and 18.6%, respectively, with a total deformation rate of 75%. The final rolling temperature is 810℃, and the rolling speed is 1 m / s. A single-pass slab with a thickness of 32 mm is obtained.

[0080] Step 5: The slab obtained in Step 4 is surface-polished and coated with a high-temperature anti-oxidation paint. After drying, it is placed in an electrically heated roller hearth furnace and heated to 1005℃, held for 35 minutes at a heating rate of 5℃ / min for a second rolling process. The rolling method is unidirectional rolling, perpendicular to the rolling direction in Step 4, completed in 6 passes. The deformation rates of each pass are 18.1%, 19.0%, 18.7%, 18.2%, 18.8%, and 19.2%, respectively, with a total deformation rate of 75%. The final rolling temperature is 800℃, and the rolling speed is 1m / s. A second-fired slab with a thickness of 8mm is obtained.

[0081] Step 6: The slab obtained in Step 5 after two passes is surface-polished and coated with a high-temperature anti-oxidation paint. After drying, it is placed in an electrically heated roller hearth furnace and heated to 1005℃, held for 10 minutes at a heating rate of 5℃ / min. Then, it undergoes three passes of rolling in a unidirectional direction, consistent with the rolling direction in Step 5. The rolling is completed in 8 passes, with the following deformation rates: 9.1%, 8.2%, 8.5%, 8.1%, 8.3%, 8.1%, 8.6%, and 8.9%, respectively. The total deformation rate is 75%. The final rolling temperature is 805℃, and the rolling speed is 1 m / s. A three-pass slab with a thickness of 2 mm is obtained.

[0082] Step 7: After surface treatment of the three-fired slab obtained in Step 6, cut it into three slabs of the same size. Stack two of the three-fired slabs together, apply a release coating to the contact surfaces, and weld them together using steel plates and edge strips. Then, load the coated stacked slabs into an electric heating roller hearth furnace, heat it to 1045℃, hold it for 5 minutes, and perform four-fire rolling. The rolling method is unidirectional rolling, with the rolling direction perpendicular to the rolling direction in Step 6). The deformation rate per fire is 50%, and it is formed in one pass. The final rolling temperature is 900℃, and the rolling speed is 1m / s. After straightening at 950℃, a 1mm thick sheet is obtained.

[0083] Step 8: Perform solution treatment and aging on the four-fired slab obtained in Step 7 to obtain a slab with uniform structure, stable performance and a thickness of 1mm; Solution treatment regime: 980℃ / 2h / OC, Aging regime: 780℃ / 24h / AC.

[0084] The finished Ti2AlNb alloy sheet underwent at least two mechanical property tests, and the results are listed in Table 1. It can be seen that the tensile properties of the sheet at room temperature and at 750℃ both meet the technical specifications. In summary, the tri-phase Ti2AlNb-based alloy sheet obtained through heat treatment exhibits excellent and stable high-temperature mechanical properties, meets room temperature toughness standards, and significantly improves its reliability in engineering applications.

[0085] Table 1. Room temperature and high temperature tensile properties of Ti2AlNb-based alloys before and after heat treatment

[0086] Table 2. High-temperature creep properties of Ti2AlNb-based alloy plates after heat treatment

[0087] Example 3 The nominal composition (atomic fraction, at.%) of the Ti2AlNb alloy ingot used in this embodiment is Ti-22Al-23Nb-0.5Mo, with the balance being Ti. The B2 phase transformation point of this alloy ingot was determined to be 1060℃ using metallographic methods. This embodiment aims to verify that a sheet material with uniform microstructure and excellent performance can still be obtained when the drawing temperature is 40℃ above the phase transformation point (i.e., 1100℃).

[0088] The specific preparation process is as follows: Step 1 (Blank Forging): Heat the Ti2AlNb alloy ingot to 1200℃ (140℃ above the B2 phase transformation point), hold for 600 min, and the heating rate is 5℃ / min to complete the three upsetting and three drawing forging. The upsetting deformation is 50%, the final forging temperature is 855℃, and the forging is air-cooled after forging to obtain a forging blank with a thickness of 280mm.

[0089] Step 2 (Slab forging, drawing temperature +40℃): Heat the forging billet to 960℃ (100℃ below the B2 phase transformation point), hold for 400 min, with a heating rate of 5℃ / min, and perform upsetting. The forging direction is axial upsetting and side drawing, and the upsetting deformation rate is 0.02s. - ¹, The upsetting deformation is 40%, and the final forging temperature is 755℃. Then the forged billet is returned to the furnace and heated to 1100℃ (40℃ above the B2 phase transformation point) for elongation forging. The final forging temperature is 860℃. After forging, it is air-cooled to obtain a slab with a thickness of 135mm.

[0090] Step 3 (Slab Forming): Heat the forging billet to 960℃ and hold for 300 minutes to complete one upsetting and one drawing forging cycle. The upsetting deformation is 40%, the single-cycle deformation of the slab is 15%, and the upsetting deformation rate is 0.02s. - ¹, The final forging temperature is 755℃, and the slab with a thickness of 112mm is obtained by air cooling after forging.

[0091] Step 4 (Single-pass rolling): The slab obtained in Step 3 is coated with a high-temperature resistant and antioxidant coating. After it dries completely, it is placed in an electrically heated roller hearth furnace and heated to 960℃, held for 280 minutes, and then rolled in one pass. The rolling method is unidirectional rolling, completed in 4 passes. The deformation rates of each pass are 16.3%, 18.8%, 17.1%, and 18.8%, respectively, with a total single-pass deformation rate of 60%. The final rolling temperature is 805℃, and the rolling speed is 4 m / s. A single-pass slab with a thickness of 45 mm is obtained.

[0092] Step 5 (Second-stage reversing rolling): Grind the surface of the first-stage slab, spray with an anti-oxidation coating, and after it dries completely, place it into an electrically heated roller hearth furnace. Heat the furnace to 960℃ and hold for 80 minutes for second-stage rolling. The rolling method is unidirectional rolling, perpendicular to step 4, completed in 4 passes. The pass deformation rates for each pass are 17.1%, 18.2%, 18.6%, and 17.9%, respectively, with a total first-stage deformation rate of 60%. The final rolling temperature is 800℃, and the rolling speed is 4 m / s. A second-stage slab with a thickness of 18 mm is obtained.

[0093] Step 6 (Three-pass finishing): Grind the surface of the second-pass slab, spray with coating, heat to 960℃ in the furnace, hold for 30 minutes, and then perform a third-pass rolling. The rolling direction is the same as in Step 5, and it is completed in 6 passes. The deformation rates of each pass are 8.0%, 6.9%, 7.6%, 8.1%, 6.6%, and 7.9%, respectively, with a total deformation rate of 60%. The final rolling temperature is 810℃, and the rolling speed is 2 m / s. A third-pass slab with a thickness of 7 mm is obtained.

[0094] Step 7 (Layer Rolling): Cut the three-fired slab into three identical slabs, apply a release coating (alumina suspension) to the contact surfaces, and weld them together with steel plates and edge strips. Load the laminated slabs into an electrically heated roller hearth furnace, heat to 1030℃ (30℃ below the B2 phase transformation point), hold for 10 minutes, and then perform four-fire rolling. The rolling method is unidirectional rolling, perpendicular to step 6, with a deformation rate of 25% per fire, formed in one pass, a final rolling temperature of 905℃, and a rolling speed of 2 m / s. After straightening at 900℃, a slab with a thickness of 5 mm is obtained.

[0095] Step 8 (Heat Treatment): The slab obtained in Step 7 is subjected to solution treatment and aging treatment. Solution treatment regime: 960℃ / 2h, oil cooling; Aging regime: 820℃ / 24h, air cooling. A 5mm thick slab is finally obtained.

[0096] Performance Testing: The sheet material underwent mechanical property testing. Results showed that the room temperature tensile strength Rm was 1092 MPa (longitudinal) and 1075 MPa (transverse), with elongation A of 10.5% (longitudinal) and 10.0% (transverse); the 750℃ high-temperature tensile strength was 763 MPa (longitudinal) and 752 MPa (transverse), with elongation of 18.0% (longitudinal) and 17.5% (transverse). The difference between the transverse and longitudinal tensile strengths did not exceed 20 MPa, fully meeting the technical requirements.

[0097] This embodiment demonstrates that when the elongation temperature is 40°C above the B2 phase transformation point, it is still possible to obtain Ti2AlNb alloy plates with uniform microstructure, good strength-plasticity matching, and low anisotropy.

[0098] Example 4 The Ti2AlNb alloy ingot used in this embodiment has the same composition as in Example 3, namely Ti-22Al-23Nb-0.5Mo, with a B2 phase transformation point of 1060℃. This embodiment aims to verify that when the deformation rate after each firing is 68% (between 60% and 75%), the formability and microstructure of the sheet metal remain excellent.

[0099] The specific preparation process is as follows: Step 1 (Blank Forging): Similar to Example 3, the ingot is heated to 1200℃, subjected to three upsetting and three drawing operations, with an upsetting deformation of 50%, and finally forged at 855℃, followed by air cooling to obtain a 280mm forging billet. The upsetting deformation rate is 0.035s. - ¹.

[0100] Step 2 (slab forging): The drawing temperature is 1090℃ (+30℃) as in Example 1, and the rest is the same as in Example 3, to obtain a 135mm slab.

[0101] Step 3 (Slab forming): Same as in Example 3, a 112mm slab is obtained.

[0102] Step 4 (Single-pass rolling, deformation rate 68%): The slab is coated with a coating and heated to 960℃ in the furnace, held for 280 minutes. The rolling method is unidirectional rolling, completed in 5 passes. The deformation rates for each pass are 15.0%, 15.0%, 20.0%, 15.0%, and 8.0%, respectively. The total deformation rate is 68% (Calculation: 1 - (1-0.15)). 4 ×(1-0.08) ≈ 0.68), the final rolling temperature is 805℃, and the rolling speed is 3m / s. A first-pass slab with a thickness of 36mm (112mm × (1-0.68) ≈36mm) is obtained.

[0103] Step 5 (Second-pass reversing rolling, 68% deformation rate per pass): After grinding and spraying the first-pass slab, heat it in the furnace to 960℃ and hold for 70 minutes. The rolling direction is perpendicular to Step 4, and it is completed in 5 passes with deformation rates of 15.0%, 15.0%, 15.0%, 15.0%, and 8.0% respectively, resulting in a total deformation rate of 68%. The final rolling temperature is 800℃, and the rolling speed is 3 m / s. A second-pass slab with a thickness of approximately 11.5 mm is obtained.

[0104] Step 6 (Three-pass finishing rolling, 68% deformation rate per pass): Grind and spray the two-pass slab, then heat it in the furnace to 960℃ and hold for 20 minutes. The rolling direction is the same as in Step 5, completed in 7 passes with deformation rates of 10%, 10%, 10%, 10%, 10%, 8%, and 5% respectively (cumulative deformation rate approximately 68%). The final rolling temperature is 810℃, and the rolling speed is 1.5 m / s. A three-pass slab with a thickness of approximately 3.7 mm is obtained.

[0105] Step 7 (Layer Rolling): Cut the three-pass slab into three sheets, stack them, apply a release coating, weld them together, heat to 1030℃, form in a single pass, with a layer deformation rate of 30%, and a final rolling temperature of 905℃. Straighten at 900℃ to obtain a slab with a thickness of approximately 2.6mm (Note: This is the thickness of a single sheet after layer rolling. The actual finished product thickness is reduced due to layer rolling. The specific value can be obtained by adjusting the layer rolling deformation rate to achieve the target thickness. This embodiment focuses on verifying the feasibility of the intermediate layer deformation rate). To obtain a 5mm finished product, the layer rolling deformation rate can be appropriately adjusted, but the core of this embodiment is to prove the feasibility of a 68% layer deformation rate.

[0106] Step 8 (Heat Treatment): Solution treatment at 960℃ for 2 hours followed by oil cooling, and aging at 820℃ for 24 hours followed by air cooling to obtain the sheet material.

[0107] Performance Testing: Mechanical property tests were conducted on the sheet material. Results showed that the room temperature tensile strength Rm was 1085 MPa (longitudinal) and 1068 MPa (transverse), with elongation A of 10.2% (longitudinal) and 9.8% (transverse). At 750℃, the high-temperature tensile strength was 758 MPa (longitudinal) and 749 MPa (transverse), with elongation of 17.8% (longitudinal) and 17.2% (transverse). The difference between transverse and longitudinal tensile strength was 17 MPa, and all indicators exceeded design requirements.

[0108] This embodiment demonstrates that a Ti2AlNb alloy plate with uniform microstructure and excellent performance can also be prepared using a heat deformation rate of 68% (between 60% and 75%), indicating that the heat deformation rate range of this application has continuous process adaptability.

[0109] Comparative Example 1: The Ti2AlNb alloy ingot used in this comparative example has the same composition as in Example 1, with a nominal composition (atomic fraction, at.%) of Ti-22Al-23Nb-0.5Mo and the balance being Ti, and a B2 phase transformation point of 1060℃.

[0110] Step S100: The Ti2AlNb alloy ingot is subjected to forging to obtain a forged blank. This step is consistent with Example 1, where the ingot is heated to 1200°C and three upsetting and three drawing processes are completed to obtain a forged blank with a thickness of 280 mm.

[0111] Step S200: The forged billet is forged into a slab to obtain a slab. Unlike Example 1, this comparative example eliminates the temperature control strategy that crosses the phase transformation point during the slab forging stage. The comparison conditions are set as follows: upsetting and drawing are performed only at temperatures above the B2 phase transformation point. Specifically, the forged billet is heated to 1090℃ (i.e., 30℃ above the B2 phase transformation point), and upsetting is performed directly at this temperature with an upsetting deformation of 40%, followed by drawing at the same temperature. The entire forging process remains within the B2 single-phase region, without experiencing the low-temperature deformation stage of the two-phase region.

[0112] Results Analysis: After the above-mentioned processing, the surface quality of the obtained slab was inspected and its microstructure was observed. Visual inspection revealed numerous visible microcracks on the slab surface, particularly densely distributed at the edges and sides. Metallographic microscopy showed coarse grains inside the slab, with an average grain diameter exceeding 200 μm, and uneven grain size distribution, exhibiting a clear mixed-grain structure. This is because, during large deformation forging in a single B2 phase region, although the material has good plasticity, the lack of pinning effect from hard α2 phase particles allows the dynamically recrystallized grains to grow rapidly at high temperatures, leading to microstructure coarsening. Simultaneously, continuous deformation in a single temperature zone results in the accumulation of deformation heat effects, further exacerbating the grain coarsening tendency through localized temperature rise. The coarse grain structure significantly reduces the material's room-temperature plasticity reserve, preventing the microcracks generated during forging from being effectively healed through subsequent phase transformation-induced plasticity mechanisms, ultimately leaving obvious crack defects on the slab surface.

[0113] As can be seen from Example 1, Example 1, through a combination of upsetting below the B2 phase transformation point and elongation above the B2 phase transformation point, refined the grains in the two-phase region by pinning grain boundaries with the α2 phase, and healed cracks in the single-phase region through high-temperature elongation, ultimately obtaining a high-quality slab with uniform microstructure and no cracks. In contrast, the slab prepared in this comparative example has a coarse microstructure and contains cracks, failing to meet the quality requirements for subsequent rolling. If forced into rolling, it is highly susceptible to edge cracking or even overall cracking, leading to a significant decrease in yield. This comparative result demonstrates the crucial role of the deformation strategy across the phase transformation point in improving microstructure uniformity and suppressing cracking.

[0114] Comparative Example 2: The Ti2AlNb alloy ingot used in this comparative example has the same composition as in Example 1, with a nominal composition (atomic fraction, at.%) of Ti-22Al-23Nb-0.5Mo and the balance being Ti, and a B2 phase transformation point of 1060℃. The preceding forging, slab forging, and slab forming steps are completely consistent with those in Example 1 to ensure the consistency of the initial state of the forged billet.

[0115] The difference from Example 1 is that this comparative example omits the reversing rolling path design during the rolling process. The comparison condition is set as follows: all rolling passes use the same rolling direction, i.e., unidirectional rolling. Specifically, in the first rolling (single-pass rolling), the temperature is raised to 960°C, and rolling is performed along the first direction; in the second rolling (double-pass rolling), the temperature is raised to 960°C, and rolling is still performed along the first direction without changing direction; in the third rolling (triple-pass rolling), the temperature is raised to 960°C, and rolling continues along the first direction. Other process parameters, such as the deformation rate per pass, the deformation rate per roll, the rolling speed, and the final rolling temperature, are consistent with those of Example 1. The subsequent stacking rolling and heat treatment processes are also the same as in Example 1.

[0116] Mechanical property tests were conducted on the prepared sheet material. The results showed that the room temperature tensile strength of the sheet material reached a high level in the longitudinal direction, but decreased significantly in the transverse direction. Specifically, the longitudinal room temperature tensile strength was 1080 MPa with an elongation of 9.5%; the transverse room temperature tensile strength was 980 MPa with an elongation of 7.0%. The difference between the transverse and longitudinal tensile strength reached 100 MPa, far exceeding the anisotropy control standard of 50 MPa. At a high temperature of 750℃, the differences in transverse and longitudinal properties were also significant, with the transverse high-temperature tensile strength being approximately 80 MPa lower than that in the longitudinal direction. This result indicates that the unidirectional rolling path led to the formation of a strong basal texture within the sheet material, with grains elongated and oriented along the rolling direction, resulting in a significant weakening of the material's mechanical properties perpendicular to the rolling direction. This significant anisotropy severely limits the reliability of the sheet material in complex load-bearing structural components and cannot meet the stringent isotropic requirements for materials in critical components such as aerospace vehicle skins and control wings. In contrast, Example 1 effectively disrupted the formation of the texture by introducing mutually perpendicular reversing rolling processes, keeping the difference between transverse and longitudinal tensile strengths within 20 MPa, demonstrating the key role of reversing rolling in improving the anisotropy of Ti2AlNb alloy plates.

[0117] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application, such as conventional adjustments to specific process parameters like forging temperature and rolling deformation within the scope defined by the claims, or substitutions using equivalent process steps with the same function, should be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A preparation process for Ti2AlNb alloy plates, characterized in that, include: The Ti2AlNb alloy ingot was forged to obtain a forged billet. The forging billet is subjected to slab forging to obtain a slab; the slab forging includes: upsetting at a temperature below the B2 phase transformation point, followed by drawing at a temperature above the B2 phase transformation point; The slab is rolled to obtain a sheet material; the rolling process includes a reversing rolling process and a stacking rolling process, the reversing rolling process includes a first rolling along a first direction and a second rolling along a second direction, the second direction being perpendicular to the first direction; the stacking rolling process includes cutting, stacking, and wrapping the sheet material before rolling.

2. The preparation process of the Ti2AlNb alloy plate according to claim 1, characterized in that, The forging process includes heating the Ti2AlNb alloy ingot to a temperature above the B2 phase transformation point and performing upsetting and drawing at least three times.

3. The preparation process of the Ti2AlNb alloy plate according to claim 1, characterized in that, In the slab forging: the upsetting temperature is in the range of 50°C to 100°C below the B2 phase transformation point; the drawing temperature is in the range of 30°C to 55°C above the B2 phase transformation point.

4. The preparation process of the Ti2AlNb alloy plate according to claim 3, characterized in that, In the slab forging process, the upsetting deformation is 40%~50%, and the upsetting deformation rate is 0.02s. - ¹~0.035s - ¹, the final forging temperature for upsetting shall not be lower than 750℃; the final forging temperature for drawing shall not be lower than 850℃, and the forging direction shall be shaft upsetting and side drawing.

5. The preparation process of the Ti2AlNb alloy plate according to claim 1, characterized in that, After the slab forging and before the rolling process, the process further includes a slab forming step: heating the slab to a temperature below the B2 phase transformation point and performing one or two upsetting and drawing operations.

6. The preparation process of the Ti2AlNb alloy plate according to claim 1, characterized in that, The first rolling and the second rolling processes are the same, both of which are: final rolling temperature not lower than 800℃, rolling method is unidirectional rolling, deformation rate per pass is 60%~75%, deformation rate per pass is 15%~20%, number of passes is 4~6, and rolling speed is 1m / s~4m / s.

7. The preparation process of the Ti2AlNb alloy plate according to claim 1, characterized in that, The rolling process further includes a third rolling process, which is located after the reversing rolling process and before the stacking rolling process. The rolling direction of the third rolling process is consistent with the second direction, and the final rolling temperature of the third rolling process is not lower than 800°C. The third rolling process has a deformation rate of 60%~75% per pass, a deformation rate of 5%~10% per pass, 6~8 passes, and a rolling speed of 1m / s~2m / s.

8. The preparation process of the Ti2AlNb alloy plate according to claim 1, characterized in that, In the stacking process, the sheet metal is cut into multiple slabs of the same size, and after applying a protective coating to the contact surfaces, they are stacked and then encased and welded with steel plates and edge strips. The heating temperature of the stacking process is 10°C to 30°C below the B2 phase transformation point, the rolling method is single-pass forming, and the final rolling temperature is not lower than 900°C.

9. The preparation process of the Ti2AlNb alloy plate according to claim 1, characterized in that, It also includes heat treatment of the plate material, which includes solution treatment and aging treatment; the solution treatment temperature is 960℃~980℃, and the cooling method is oil cooling or air cooling; the aging treatment temperature is 780℃~820℃, and the cooling method is air cooling.

10. A Ti2AlNb alloy plate, characterized in that, The Ti2AlNb alloy sheet is prepared by the preparation process of any one of claims 1 to 9; the thickness of the Ti2AlNb alloy sheet is 1 mm to 5 mm; the microstructure of the Ti2AlNb alloy sheet is a three-state structure composed of equiaxed α2 / O particles, coarse lath α2 / O phase and metastable B2 phase; the room temperature tensile strength of the Ti2AlNb alloy sheet is greater than 1000 MPa and the elongation is greater than 8%, the 750℃ tensile strength is greater than 750 MPa and the elongation is greater than 12%; the difference between the transverse and longitudinal tensile strengths does not exceed 50 MPa.

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