Large-scale ti2alnab alloy sheet and method of making

Abstract

The application relates to the alloy processing technical field, in particular to a large-specification Ti2AlNb alloy sheet and a preparation method thereof. The preparation method comprises the following steps: (a) carrying out one-pass rolling on a Ti2AlNb alloy slab along the width and length directions respectively at 1050-1100 DEG C to obtain an intermediate slab; and carrying out annealing treatment on the intermediate slab at 1000-1045 DEG C; (b) carrying out one-pass rolling on the annealed intermediate slab along the width and length directions respectively at 850-980 DEG C, carrying out cladding rolling along the length direction, and then carrying out annealing treatment at 800-950 DEG C. The application sequentially carries out high-temperature reversing rolling, intermediate annealing, low-temperature reversing rolling and post-rolling annealing, controls the transverse and longitudinal deformation amounts of the high-temperature reversing rolling and the low-temperature reversing rolling, guarantees the mechanical properties of the sheet and reduces the transverse and longitudinal performance difference of the sheet.

Description

Technical Field

[0001] This invention relates to the field of alloy processing technology, and in particular to a large-size Ti2AlNb alloy thin plate and its preparation method. Background Technology

[0002] Ti2AlNb alloy belongs to the titanium-aluminum intermetallic compound structural material. This alloy has the advantages of low density, good flame retardancy, high specific strength, high fracture toughness, and good high-temperature creep resistance. It is a structural material that can be used for long-term service at 600-750℃ or for short-term application at higher temperatures. It shows great application potential, especially in aerospace structural materials. It is of great significance for improving the thrust-to-weight ratio of aircraft, improving fuel efficiency, and enhancing high-temperature service performance.

[0003] With the rapid development of the aerospace industry, high-speed aircraft place higher demands on the load-bearing capacity and temperature resistance of thin-walled complex components such as wings and air intakes. Simultaneously, as the size of the aircraft increases, the size of the components also increases accordingly, thus creating greater demand for large-format Ti2AlNb alloy sheets. During high-speed flight, thin-walled components will be subjected to severe aerodynamic and thermal coupling effects. In service, components often experience severe force / thermal coupling effects in multiple directions, requiring materials with low anisotropy and ensuring as much uniformity in microstructure and properties as possible. Ti2AlNb alloy sheets prepared using conventional processes exhibit significant differences in transverse and longitudinal properties, and are prone to irregular deformation during component fabrication, making it difficult to meet the dimensional accuracy requirements of the components.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide large-size Ti2AlNb alloy thin plates and their preparation methods. The preparation method of this invention can obtain large-size Ti2AlNb alloy thin plates with low transverse and longitudinal differences, laying a good foundation for the preparation of large-size thin-walled complex structural parts for aerospace applications.

[0006] To achieve the above-mentioned objectives of the present invention, the first aspect of the present invention provides a method for preparing large-size Ti2AlNb alloy thin plates, comprising the following steps:

[0007] (a) The Ti2AlNb alloy slab is rolled at 1050-1100℃ in both the width and length directions to obtain an intermediate slab; the intermediate slab is then annealed at 1000-1045℃.

[0008] (b) The intermediate slab after annealing is rolled at 850-980°C in both the width and length directions, and then rolled in the length direction; then annealed at 800-935°C to obtain the Ti2AlNb alloy sheet.

[0009] In a specific embodiment of the present invention, in step (a), the deformation amount in the first-pass rolling along the width direction is 30% to 50%, and the deformation amount in the first-pass rolling along the length direction is 40% to 60%.

[0010] In a specific embodiment of the present invention, in step (b), the deformation amount in the first-pass rolling along the width direction is 35% to 75%, and the deformation amount in the first-pass rolling along the length direction is 10% to 45%.

[0011] In a specific embodiment of the present invention, the deformation amount of the cladding rolling is 30% to 90%.

[0012] In a specific embodiment of the present invention, in step (a), the annealing time is 30 to 240 minutes.

[0013] In a specific embodiment of the present invention, in step (b), the annealing time is 10 to 240 minutes.

[0014] In a specific embodiment of the present invention, the thickness of the Ti2AlNb alloy slab is 100-200 mm.

[0015] In a specific embodiment of the present invention, the thickness of the intermediate slab is 12 to 40 mm.

[0016] In a specific embodiment of the present invention, in step (b), the intermediate slab after annealing is rolled at 850-980°C in both the width and length directions, and the thickness of the slab is 4-10 mm.

[0017] In a specific embodiment of the present invention, the thickness of the Ti2AlNb alloy sheet is 1 to 2 mm.

[0018] The second aspect of the present invention provides a large-size Ti2AlNb alloy sheet prepared by the method of the first aspect of the present invention.

[0019] In a specific embodiment of the present invention, the large-size Ti2AlNb alloy sheet has a tensile strength ≥1000MPa, a yield strength ≥850MPa, and an elongation ≥6.0% at room temperature of 23℃; and a tensile strength ≥700MPa, a yield strength ≥450MPa, and an elongation ≥19.0% at high temperature of 650℃.

[0020] In a specific embodiment of the present invention, the ratio of the difference between the longitudinal and transverse tensile strengths to the transverse tensile strength of the large-size Ti2AlNb alloy sheet at room temperature of 23°C is ≤5%, and the ratio of the difference between the longitudinal and transverse yield strengths to the transverse yield strength is ≤5% at room temperature of 23°C; the ratio of the difference between the longitudinal and transverse tensile strengths to the transverse tensile strength is ≤6% at high temperature of 650°C, and the ratio of the difference between the longitudinal and transverse yield strengths to the transverse yield strength is ≤6% at high temperature of 650°C.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) The preparation method of the large-size Ti2AlNb alloy thin plate of the present invention involves sequentially processing high-temperature reversing rolling, intermediate annealing, low-temperature reversing rolling and post-rolling annealing, and coordinating the control of the transverse and longitudinal deformation of high-temperature reversing rolling and low-temperature reversing rolling, so as to ensure the mechanical properties of the plate and reduce the difference in transverse and longitudinal properties of the plate.

[0023] (2) The preparation method of the present invention is applicable to the preparation of large-size Ti2AlNb alloy thin plates. The large-size Ti2AlNb alloy thin plates prepared not only have low differences in transverse and longitudinal properties, but also have good room temperature and high temperature strength and plasticity, which lays a good foundation for the subsequent preparation of aerospace thin-walled complex structural parts. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 The crystal orientation distribution diagram of the plate obtained in step (2) of Embodiment 1 of the present invention;

[0026] Figure 2 The crystal orientation distribution diagram of the plate obtained in step (3) of Embodiment 1 of the present invention;

[0027] Figure 3 This is a longitudinal microstructure image of the Ti2AlNb alloy thin plate prepared in Example 1 of the present invention;

[0028] Figure 4 This is a transverse microstructure diagram of the Ti2AlNb alloy thin plate prepared in Example 1 of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0030] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] Currently, in the preparation of Ti2AlNb alloy thin plates, improper control of rolling processes leads to significant transverse and longitudinal differences, making it difficult to meet the service requirements of thin-walled complex components in aerospace applications. While multiple reversing rolling processes can make the transverse and longitudinal deformation amounts roughly equal and appropriately improve the transverse and longitudinal performance differences, current methods for improving these differences cannot meet higher requirements. Furthermore, the room temperature and high temperature properties of the resulting Ti2AlNb alloy thin plates are relatively low, and the production efficiency of Ti2AlNb alloy thin plates is low.

[0032] Based on this, the first aspect of the present invention provides a method for preparing large-size Ti2AlNb alloy thin plates, comprising the following steps:

[0033] (a) The Ti2AlNb alloy slab is rolled in one heat along the width and length directions at 1050-1100℃ to obtain an intermediate slab; the intermediate slab is annealed at 1000-1045℃.

[0034] (b) The annealed intermediate slab is rolled at 850-980°C in both the width and length directions, and then rolled in the length direction; then annealed at 800-935°C to obtain Ti2AlNb alloy sheet.

[0035] The method for preparing large-size Ti2AlNb alloy thin plates of the present invention involves sequentially performing high-temperature reversing rolling, intermediate annealing, low-temperature reversing rolling, and post-rolling annealing. By controlling the transverse and longitudinal deformation amounts during high-temperature and low-temperature reversing rolling, the mechanical properties of the plate are guaranteed while reducing the difference in transverse and longitudinal properties.

[0036] The process involves first rolling a Ti2AlNb alloy slab in a single pass along its width at a rolling temperature range of 1050–1100℃, followed by a single pass along its length to obtain an intermediate slab. The rolling temperature in this stage can be any combination of 1050℃, 1060℃, 1070℃, 1080℃, 1090℃, and 1100℃. At this rolling temperature, the hot deformation properties of the Ti2AlNb alloy, combined with rolling with large deformation, significantly improve the homogenization of the grain structure, eliminate internal defects, and enhance the material's strength and plasticity. Simultaneously, it effectively shortens the overall rolling cycle, increasing yield and production efficiency. Furthermore, research has shown that at this rolling temperature, combined with subsequent annealing at a specific temperature, the anisotropy of the slab is further reduced, resulting in an intermediate slab without a significant preferred orientation, while simultaneously improving the homogenization of the microstructure, ensuring or even improving room temperature / high temperature strength and plasticity. The annealing temperature can be 1000℃, 1010℃, 1020℃, 1030℃, 1040℃, 1045℃, or any combination thereof.

[0037] After annealing the intermediate slab, it is rolled once along the width at a rolling temperature range of 850–980℃, followed by a single-pass rolling along the length. Then, according to the target sheet size requirements, it undergoes cladding rolling along the length. The rolling temperature in this stage can be 850℃, 880℃, 900℃, 920℃, 950℃, 980℃, or any combination thereof. By reducing the rolling temperature after high-temperature rolling and intermediate annealing, the grain size of the sheet is effectively refined while maintaining low transverse and longitudinal differences, improving the sheet's mechanical properties and enhancing its room temperature and high-temperature plasticity. Further annealing is performed after the above rolling process. The annealing temperature can be 800℃, 820℃, 850℃, 880℃, 900℃, 920℃, 935℃, or any combination thereof.

[0038] In a specific embodiment of the present invention, in step (a), the annealing time is 30 to 240 minutes. For example, the annealing time can be 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, 210 minutes, 240 minutes, or any combination thereof.

[0039] In a specific embodiment of the present invention, in step (b), the annealing time is 10 to 240 minutes. For example, the annealing time can be 10 minutes, 40 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, 240 minutes, or any combination thereof.

[0040] After the above annealing treatment is completed and the heat preservation is finished, air cooling treatment shall be performed unless otherwise specified.

[0041] It should be noted that the “width direction” and “length direction” in this invention refer to the width direction Y and length direction X of the initial Ti2AlNb alloy slab, respectively. They are perpendicular to each other and are also perpendicular to the thickness direction Z of the initial Ti2AlNb alloy slab.

[0042] In practice, rolling includes: rolling after holding the slab at the rolling temperature. The holding time is determined based on the slab thickness. The holding time for cold material charged into the furnace is calculated at 0.5–0.8 min / mm, and the holding time for hot material returned to the furnace is calculated at 0.2–0.4 min / mm. The specific holding time can be controlled between 10 and 240 min.

[0043] In a specific embodiment of the present invention, in step (a), the deformation amount in the first-pass rolling along the width direction is 30% to 50%, and the deformation amount in the first-pass rolling along the length direction is 40% to 60%.

[0044] It should be noted that the deformation amount in this invention is calculated as follows:

[0045] (Thickness of sheet material before deformation - Thickness of sheet material after deformation) / Thickness of sheet material before deformation × 100%.

[0046] In different embodiments, in step (a), during the one-time rolling along the width direction, the deformation amount can be a range of 30%, 35%, 40%, 45%, 50%, or any combination thereof; during the one-time rolling along the length direction, the deformation amount can be a range of 40%, 45%, 50%, 55%, 60%, or any combination thereof. Using the relatively high rolling temperature in step (a), combined with the aforementioned deformation amount, helps to balance improved processing efficiency, low anisotropy, and uniform grain size of the sheet.

[0047] In a specific embodiment of the present invention, in step (b), the deformation amount in the first-pass rolling along the width direction is 35% to 75%, and the deformation amount in the first-pass rolling along the length direction is 10% to 45%.

[0048] In different embodiments, in step (b), during the single-pass rolling along the width direction, the deformation amount can be a range of 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or any combination thereof; during the single-pass rolling along the length direction, the deformation amount can be a range of 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or any combination thereof. Using the low rolling temperature in step (b), combined with the aforementioned deformation amounts, helps to balance refining the grain size of the sheet and ensuring sheet quality.

[0049] In a specific embodiment of the present invention, in step (a), during the single-fire rolling along the width and length directions, the rolling passes of each fire are independently selected from 2 to 8 passes.

[0050] In a specific embodiment of the present invention, in step (b), during the single-fire rolling along the width and length directions, the rolling passes of each fire are independently selected from 2 to 8 passes.

[0051] In a specific embodiment of the present invention, the deformation amount of the cladding rolling is 30% to 90%, for example, it can be a range of 30%, 40%, 50%, 60%, 70%, 80%, 90%, or any combination thereof.

[0052] In practice, the slab can be divided into multiple equal parts and then rolled over and clad. The specific number of equal parts can be adjusted according to the slab and cladding dimensions.

[0053] In a specific embodiment of the present invention, the thickness of the Ti2AlNb alloy slab is 100–200 mm. Specifically, the thickness can be 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, or any combination thereof.

[0054] In a specific embodiment of the present invention, the thickness of the intermediate slab is 12 to 40 mm, for example, it can be a range of 12 mm, 16 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm or any combination thereof.

[0055] In a specific embodiment of the present invention, in step (b), after the annealed intermediate slab is rolled at 850-980°C in both the width and length directions, the thickness of the slab is 4-10 mm, for example, it can be 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm or any combination thereof.

[0056] In a specific embodiment of the present invention, the thickness of the Ti2AlNb alloy sheet is 1-2 mm. Further, the length of the Ti2AlNb alloy sheet is >1000 mm, and the width is >800 mm.

[0057] In a specific embodiment of the present invention, the Ti2AlNb alloy slab is mainly obtained by multi-stage forging of Ti2AlNb alloy ingots. The multi-stage forging includes: the Ti2AlNb alloy ingot undergoing conventional three-upsetting and three-drawing processes at 1170℃, 1080℃, 1030℃, and 980℃ respectively, followed by forging at 980℃ to form the Ti2AlNb alloy slab.

[0058] The second aspect of the present invention provides a large-size Ti2AlNb alloy sheet prepared by the method of the first aspect of the present invention.

[0059] In a specific embodiment of the present invention, the large-size Ti2AlNb alloy sheet has a tensile strength ≥1000MPa, a yield strength ≥850MPa, and an elongation ≥6.0% at room temperature of 23℃; and a tensile strength ≥700MPa, a yield strength ≥450MPa, and an elongation ≥19.0% at high temperature of 650℃.

[0060] In different embodiments, the tensile strength of large-size Ti2AlNb alloy sheets at room temperature (23°C) can be in the range of 1000MPa, 1050MPa, 1100MPa, 1150MPa, 1160MPa, or any combination thereof; the yield strength can be in the range of 850MPa, 900MPa, 1000MPa, 1050MPa, 1100MPa, or any combination thereof; and the elongation can be in the range of 8.0%, 8.5%, 9%, 9.5%, 9.5%, 10.0%, or any combination thereof. The tensile strength at 650℃ can be 750MPa, 760MPa, 770MPa, 780MPa, 790MPa, 800MPa or any combination thereof; the yield strength can be 620MPa, 630MPa, 640MPa, 650MPa or any combination thereof; and the elongation can be 19.0%, 19.5%, 20%, 21%, 22%, 22.5% or any combination thereof.

[0061] In a specific embodiment of the present invention, the ratio of the difference between the longitudinal and transverse tensile strengths to the transverse tensile strength of large-size Ti2AlNb alloy thin plates at room temperature of 23°C is ≤5%, preferably ≤3%, and can be, for example, a range of 5%, 4%, 3%, 2%, 1%, 0.5%, or any two of these; the ratio of the difference between the longitudinal and transverse yield strengths to the transverse yield strength at room temperature of 23°C is ≤5%, preferably ≤3%, and can be, for example, a range of 5%, 4%, 3%, 2%, 1%, 0.5%, or any two of these; the ratio of the difference between the longitudinal and transverse tensile strengths to the transverse tensile strength at a high temperature of 650°C is ≤6%, preferably ≤3%, and can be, for example, a range of 6%, 4%, 2%, 1%, 0.5%, or any two of these; the ratio of the difference between the longitudinal and transverse yield strengths to the transverse yield strength at a high temperature of 650°C is ≤6%, preferably ≤3%, and can be, for example, a range of 6%, 4%, 2%, 1%, 0.5%, or any two of these.

[0062] The Ti2AlNb alloy of the present invention is illustrated using Ti-22Al-25Nb (at.%) as an example, but is not limited thereto.

[0063] Example 1

[0064] This embodiment provides a method for preparing large-size Ti2AlNb alloy thin plates, including the following steps:

[0065] (1) Ti2AlNb alloy ingots were obtained by a combination of vacuum self-consuming electric arc melting and vacuum solidification melting. The ingots were subjected to three upsetting and three drawing at 1170℃, three upsetting and three drawing at 1080℃, three upsetting and three drawing at 1030℃, and three upsetting and three drawing at 980℃. Then, they were forged at 980℃ into Ti2AlNb alloy slabs with dimensions of X×Y×Z=900mm×800mm×150mm.

[0066] (2) The Ti2AlNb alloy slab obtained in step (1) is held at 1060℃ for 120 min and then rolled in one heat along the Y direction (width direction) to obtain a slab with dimensions X×Y×Z=900mm×1333mm×90mm; then it is returned to the furnace for reheating for 30 min and rolled in one heat along the X direction (length direction) to obtain an intermediate slab with dimensions X×Y×Z=2250mm×1333mm×36mm; wherein, the deformation of the one heat rolling along the Y direction is 40%, and the deformation of the one heat rolling along the X direction is 60%; the one heat rolling along the Y direction includes 7 passes, and the thickness reduction of each pass is 12mm, 11mm, 9mm, 8mm, 7mm, 7mm, 6mm respectively; the one heat rolling along the X direction includes 6 passes, and the thickness reduction of each pass is 11mm, 10mm, 9mm, 9mm, 8mm, 7mm respectively.

[0067] (3) After annealing and holding the intermediate slab obtained in step (2) at 1040℃ for 120 minutes, air-cool it, and then grind, trim and slit it to obtain an annealed intermediate slab with dimensions of X×Y×Z=1000mm×1280mm×35mm.

[0068] (4) After annealing the intermediate slab in step (3), the slab is held at 930℃ for 160 min and then rolled in one heat along the Y direction (width direction) to obtain a plate with dimensions X×Y×Z=1000mm×3200mm×14mm. Then, it is ground, trimmed, and slit to obtain a plate with dimensions X×Y×Z=980mm×1500mm×13mm. Then, the plate is held at 930℃ for 30 min and then rolled in one heat along the X direction (length direction) to obtain a plate with dimensions X×Y×Z=1592mm×1500mm×8mm. Then, it is ground, trimmed, and slit to obtain two plates with dimensions X×Y×Z=750mm×1500mm×7mm. Then, the two plates are stacked in a steel cladding with a thickness of 54mm and held at 930℃ for 120 min. Subsequently, a plate with dimensions of X×Y×Z=2280mm×1500mm×2.3mm is obtained by rolling along the X direction (length direction). Among them, the deformation of the first rolling along the Y direction is 60%, the deformation of the first rolling along the X direction is 38%, and the deformation of the cladding rolling along the X direction is 67%. The first rolling along the Y direction includes 8 passes, and the thickness reduction of each pass is 4mm, 3mm, 3mm, 3mm, 3mm, 2mm, 2mm, and 1mm respectively. The first rolling along the X direction includes 6 passes, and the thickness reduction of each pass is 2mm, 1mm, 1mm, 1mm, 0.5mm, and 0.5mm. The cladding rolling along the X direction includes 6 passes, and the thickness reduction of each pass of the steel cladding is 10mm, 8mm, 8mm, 6mm, 5mm, and 4mm respectively.

[0069] (5) The plate obtained in step (4) is kept at 850℃ for 60 minutes. After the heat preservation is completed, it is directly leveled by multi-roller, then sanded, trimmed and pickled to obtain a Ti2AlNb alloy thin plate with dimensions of X×Y×Z=2000mm×1400mm×2mm.

[0070] Example 2

[0071] This embodiment refers to the preparation method of large-size Ti2AlNb alloy thin plate in embodiment 1, with the only difference being: in step (2), the rolling holding temperature is 1100℃; in step (3), the annealing holding temperature is 1045℃; in step (4), the rolling holding temperature is 980℃; and in step (5), the annealing holding temperature is 935℃.

[0072] Example 3

[0073] This embodiment refers to the preparation method of large-size Ti2AlNb alloy thin plate in embodiment 1, with the only difference being: in step (2), the rolling holding temperature is 1050℃; in step (3), the annealing holding temperature is 1000℃; in step (4), the rolling holding temperature is 850℃; and in step (5), the annealing holding temperature is 800℃.

[0074] Comparative Example 1

[0075] Comparative Example 1 refers to the preparation method of the large-size Ti2AlNb alloy thin plate of Example 1, the difference being that step (3) is different.

[0076] Step (3) of Comparative Example 1 is as follows: Grind, trim and cut the intermediate slab obtained in step (2) to obtain an intermediate slab with dimensions of X×Y×Z=1000mm×1280mm×35mm.

[0077] Comparative Example 2

[0078] Comparative Example 2 uses the same method as Example 1 for preparing large-size Ti2AlNb alloy thin plates, but the difference lies in step (3).

[0079] Step (3) of Comparative Example 2 is as follows: the intermediate slab obtained in step (2) is annealed at 980℃ for 120 minutes, then air-cooled, and then ground, trimmed and cut to obtain an intermediate slab with dimensions of X×Y×Z=1000mm×1280mm×35mm.

[0080] Comparative Example 3

[0081] Comparative Example 3 uses the same method as Example 1 for preparing large-size Ti2AlNb alloy thin plates, but the difference lies in step (3).

[0082] Step (3) of Comparative Example 3 is as follows: the intermediate slab obtained in step (2) is annealed at 1080℃ and held for 120 minutes, then air-cooled, and then ground, trimmed and cut to obtain an intermediate slab with dimensions of X×Y×Z=1000mm×1280mm×35mm.

[0083] Comparative Example 4

[0084] Comparative Example 4 refers to the preparation method of large-size Ti2AlNb alloy thin plates in Example 1, the difference being that the rolling and holding temperatures are different in step (2).

[0085] In step (2) of Comparative Example 4, the rolling and heat preservation temperature was 1150℃.

[0086] Comparative Example 5

[0087] Comparative Example 5 refers to the preparation method of large-size Ti2AlNb alloy thin plates in Example 1, the difference being that the rolling and holding temperatures are different in step (2).

[0088] In step (2) of Comparative Example 5, the rolling and heat preservation temperature was 1000℃.

[0089] Comparative Example 6

[0090] The preparation method of the large-size Ti2AlNb alloy thin plate of Comparative Example 6 is the same as that of Example 1, except that the rolling and holding temperature is different in step (4).

[0091] In step (4) of Comparative Example 6, the rolling and heat preservation temperature was 1000℃.

[0092] Comparative Example 7

[0093] Comparative Example 7 refers to the preparation method of large-size Ti2AlNb alloy thin plates in Example 1, the difference being that the rolling and holding temperatures are different in step (4).

[0094] In step (4) of Comparative Example 7, the rolling and heat preservation temperature was 830℃.

[0095] Comparative Example 8

[0096] The preparation method of the large-size Ti2AlNb alloy thin plate of Comparative Example 8 is the same as that of Example 1, except that the annealing and holding temperature is different in step (5).

[0097] In step (5) of Comparative Example 8, the annealing holding temperature is 960℃.

[0098] Experimental Example

[0099] Figures 1-2 The figures show the crystal orientation distribution of the plates obtained in step (2) and step (3) of Embodiment 1 of the present invention, respectively. As can be seen from the figures, the high-temperature reversing rolling of the present invention, combined with a certain annealing treatment, is beneficial for obtaining plates without a clear preferred orientation. Figure 3 This is a longitudinal cross-sectional microstructure diagram of the Ti2AlNb alloy thin plate prepared in Example 1 of the present invention. Figure 4 This is a cross-sectional microstructure diagram of the Ti2AlNb alloy thin plate prepared in Example 1 of the present invention.

[0100] The mechanical properties of the Ti2AlNb alloy thin plates prepared in different embodiments and comparative examples were further tested, and the test results are shown in Tables 1 and 2.

[0101] Table 1. Test results of mechanical properties of different Ti2AlNb alloy thin plates at room temperature (23℃)

[0102]

[0103]

[0104] Table 2. High-temperature (650℃) mechanical property test results of different Ti2AlNb alloy thin plates

[0105]

[0106] The test results above show that the Ti2AlNb alloy thin plates obtained by the preparation method of the present invention have basically the same mechanical properties in the transverse and longitudinal directions at room temperature and high temperature, which can lay a good foundation for the subsequent molding of large-size aerospace thin-walled complex structural parts.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing large-size Ti2AlNb alloy thin plates, characterized in that, Includes the following steps: (a) The Ti2AlNb alloy slab is rolled at 1050-1100℃ in both the width and length directions to obtain an intermediate slab; the intermediate slab is then annealed at 1000-1045℃. (b) The annealed intermediate slab is rolled at 850-980°C in both the width and length directions, and then rolled in the length direction; then annealed at 800-935°C to obtain the Ti2AlNb alloy sheet. In step (a), the deformation in the single-rolling along the width direction is 30%–50%, and the deformation in the single-rolling along the length direction is 40%–60%; in step (b), the deformation in the single-rolling along the width direction is 35%–75%, and the deformation in the single-rolling along the length direction is 10%–45%; the deformation in the cladding rolling is 30%–90%. The thickness of the Ti2AlNb alloy sheet is 1-2 mm, the length is >1000 mm, and the width is >800 mm.

2. The preparation method according to claim 1, characterized in that, In step (a), the annealing process takes 30 to 240 minutes.

3. The preparation method according to claim 1, characterized in that, In step (b), the annealing process takes 10 to 240 minutes.

4. The preparation method according to claim 1, characterized in that, It has at least one of the following characteristics: (1) The thickness of the Ti2AlNb alloy slab is 100-200 mm; (2) The thickness of the intermediate slab is 12-40 mm; (3) In step (b), the intermediate slab after annealing is rolled at 850-980°C in both the width and length directions, and the thickness of the slab is 4-10 mm.

5. Large-format Ti2AlNb alloy thin plates, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 4.

6. The large-size Ti2AlNb alloy thin plate according to claim 5, characterized in that, The large-size Ti2AlNb alloy sheet has a tensile strength ≥1000MPa, a yield strength ≥850MPa, and an elongation ≥6.0% at room temperature (23℃); and a tensile strength ≥700MPa, a yield strength ≥450MPa, and an elongation ≥19.0% at high temperature (650℃).

7. The large-size Ti2AlNb alloy thin plate according to claim 5, characterized in that, The ratio of the difference between the longitudinal and transverse tensile strengths to the transverse tensile strength of the large-size Ti2AlNb alloy sheet at room temperature of 23℃ is ≤5%, and the ratio of the difference between the longitudinal and transverse yield strengths to the transverse yield strength is ≤5% at room temperature of 23℃; the ratio of the difference between the longitudinal and transverse tensile strengths to the transverse tensile strength is ≤6% at high temperature of 650℃, and the ratio of the difference between the longitudinal and transverse yield strengths to the transverse yield strength is ≤6% at high temperature of 650℃.

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