Preparation method of high-strength plastic Ti-Al-Nb alloy plate for aerospace vehicles

Abstract

The application discloses a preparation method of high-strength plastic Ti-Al-Nb alloy plate for aerospace vehicles, and the method comprises the following steps: firstly, a Ti-Al-Nb alloy ingot is heated and kept at different temperatures in sequence and then forged to obtain a Ti-Al-Nb forged plate blank; secondly, the Ti-Al-Nb forged plate blank is heated and kept and then rolled to obtain a Ti-Al-Nb alloy hot-rolled plate; and thirdly, the Ti-Al-Nb alloy hot-rolled plate is subjected to solid solution and aging treatment. The finished product is obtained by adopting the forging + rolling process combined with the solid solution and aging heat treatment, the preparation efficiency of the Ti-Al-Nb alloy is fully improved by strictly controlling the heat processing and heat treatment parameters, and the performance of the Ti-Al-Nb alloy plate is improved, so that the Ti-Al-Nb alloy plate prepared has high plasticity and excellent comprehensive mechanical properties and is suitable for aerospace fields and the like.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal processing technology, specifically to a method for preparing high-strength, ductile Ti-Al-Nb alloy plates for aerospace vehicles. Background Technology

[0002] In the research and production of spacecraft, weight reduction can effectively improve the carrying capacity and operational efficiency of spacecraft. Meanwhile, due to the demanding service conditions of aero-engines, the materials required for their manufacture must not only have good room temperature performance but also excellent high-temperature performance and good machinability. Currently, high-density nickel-based superalloys are the main materials used in this field, but their high density and large weight are significant drawbacks. While traditional titanium and titanium alloys are widely used in aerospace, their limited high-temperature oxidation resistance and creep resistance limit their application to temperatures below 600℃. Compared to traditional high-temperature titanium alloys, Ti-Al alloys have low density, high specific strength, and good oxidation resistance, making them an important material choice for high-temperature lightweight structural components in aerospace applications above 650℃. Ti-Al-Nb alloys are an important branch of Ti-Al alloys, with a service temperature of 650℃~750℃. They solve the 600℃ "thermal barrier" problem of traditional titanium alloys and have promising applications in the field of high-temperature structural materials for aerospace, particularly suitable for manufacturing hot-end parts of aerospace engines, such as engine blades and turbine disks. However, the low plasticity, toughness, and inherent brittleness of Ti-Al-Nb alloys, as intermetallic compounds, severely limit their widespread application. Furthermore, Ti-Al-Nb-based alloys have a narrow hot working window, and their microstructure and properties are highly susceptible to temperature influences, resulting in generally poor performance of rolled sheets. Therefore, optimizing the composition of Ti-Al-Nb-based alloys and improving their processing properties to enhance their plasticity and machinability, achieve a strong-plasticity-strength balance, and obtain high-performance Ti-Al-Nb-based alloy sheets remains a problem to be solved in the field of Ti-Al-Nb alloy sheet preparation. Summary of the Invention

[0003] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for preparing high-strength, high-ductility Ti-Al-Nb alloy sheets for aerospace vehicles. This invention employs a forging and rolling process combined with solution aging heat treatment to obtain the finished product. By strictly controlling the hot working and heat treatment parameters, the preparation efficiency of the Ti-Al-Nb alloy is significantly improved, and the performance of the Ti-Al-Nb alloy sheet is enhanced. The resulting Ti-Al-Nb alloy sheet exhibits high ductility and excellent comprehensive mechanical properties, solving the problems of poor ductility and high processing difficulty in the prior art for Ti-Al-Nb alloy sheets.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing high-strength and ductile Ti-Al-Nb alloy plates for aerospace vehicles, characterized in that the method includes the following steps:

[0005] Step 1: Forging

[0006] Step 101: Peel and saw the Ti-Al-Nb alloy ingot, then heat and hold it at 100℃~150℃ above the phase transformation point. After taking it out of the furnace, perform one-fire forging on a high-speed forging machine. After forging, air cool it to obtain a one-fire forged billet.

[0007] Step 102: Heat the forged billet obtained in step 101 at 100°C above the phase transformation point and hold it at that temperature. After it comes out of the furnace, perform re-forging above the phase transformation point on a high-speed forging machine. After forging, air cool it to obtain the first re-forged billet. The re-forging above the phase transformation point is completed in 1 to 2 heats.

[0008] Step 103: Heat and hold the first modified forging billet obtained in step 102 at 20°C to 40°C below the phase transformation point. After taking it out of the furnace, perform modified forging below the phase transformation point on a high-speed forging machine. After forging, air cool to obtain the second modified forging billet. The modified forging below the phase transformation point is completed in 1 to 2 heats.

[0009] Step 104: Heat and hold the second modified forging billet obtained in step 103 at 80℃~100℃ below the phase transformation point. After taking it out of the furnace, forge the billet on a high-speed forging machine. After forging, air cool it to obtain Ti-Al-Nb forged billet.

[0010] Step 2: Hot rolling

[0011] The surface of the Ti-Al-Nb forged slab obtained in step 104 is coated with a high-temperature resistant protective coating. After the protective coating dries completely, it is placed in a heating furnace for heating and heat preservation treatment. After being taken out of the furnace, the slab is rolled to obtain a hot-rolled Ti-Al-Nb alloy slab. The slab rolling is completed in 1 to 2 passes according to the target thickness of the hot-rolled Ti-Al-Nb alloy slab.

[0012] Step 3: Heat Treatment

[0013] The hot-rolled Ti-Al-Nb alloy sheet obtained in step two is solution treated in an atmospheric furnace and then aged to obtain a high-strength and high-ductility Ti-Al-Nb alloy sheet. The high-strength and high-ductility Ti-Al-Nb alloy sheet has a tensile strength Rm≥1050MPa, a yield strength Rp0.2≥900MPa, and an elongation after fracture A≥13%.

[0014] The above-mentioned method for preparing a high-strength, high-ductility Ti-Al-Nb alloy sheet for aerospace vehicles is characterized in that the Ti-Al-Nb alloy ingot in step 101 is composed of the following components by mass percentage: Al 13%–14%, Nb 35%–38%, Mo 0.8%–1.0%, N ≤ 0.03%, H ≤ 0.01%, O ≤ 0.15%, with the balance being Ti and unavoidable impurities.

[0015] The above-mentioned method for preparing a high-strength, ductile Ti-Al-Nb alloy sheet for aerospace vehicles is characterized in that, before each forging in step one, a high-temperature resistant protective coating is applied to the surface of the forging object.

[0016] The above-mentioned method for preparing a high-strength and ductile Ti-Al-Nb alloy plate for aerospace vehicles is characterized in that, in the forging process described in step one, the deformation method of each forging is two upsetting and two drawing, and the deformation amount of each forging is more than 115%.

[0017] The above-mentioned method for preparing a high-strength and ductile Ti-Al-Nb alloy sheet for aerospace vehicles is characterized in that, in the forging process described in step one, the heating and holding time for the first forging is 0.4 to 0.7 times the diameter of the cylindrical Ti-Al-Nb alloy ingot, and the heating and holding time for each subsequent forging is 0.6 times the thickness of the corresponding forging blank. The unit of heating and holding time is min, and the unit of diameter and thickness is mm.

[0018] The above-mentioned method for preparing a high-strength and ductile Ti-Al-Nb alloy sheet for aerospace vehicles is characterized in that the rolling in step two is unidirectional rolling, and the deformation per pass is 60% to 80%, and the deformation per single pass is 10% to 15%.

[0019] The above-mentioned method for preparing a high-strength, ductile Ti-Al-Nb alloy sheet for aerospace vehicles is characterized in that the solution treatment temperature in step three is 900℃~950℃ and the holding time is 90min~120min; the aging treatment temperature is 650℃~720℃ and the holding time is 8h~10h; and the cooling method is air cooling.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. This invention, from the perspective of processing technology and heat treatment, adopts a forging and rolling process combined with solution aging heat treatment to obtain the finished product. By strictly controlling the hot working and heat treatment parameters, the preparation efficiency of Ti-Al-Nb alloy is fully improved, and the performance of Ti-Al-Nb alloy plate is improved. The resulting Ti-Al-Nb alloy plate has a uniform structure, stable performance, high strength-plasticity matching, and good comprehensive mechanical properties.

[0022] 2. This invention, by adding Mo to Ti-Al-Nb alloy to replace part of Nb, effectively refines the microstructure, improves the creep resistance and high-temperature performance of the alloy without affecting the yield strength and plasticity, and helps to improve the processing performance and comprehensive mechanical properties of Ti-Al-Nb alloy.

[0023] 3. This invention applies a high-temperature resistant protective coating to the surface of the forging object before each forging pass, and simultaneously preheats the forging anvil and hammer. This effectively prevents surface cooling during forging, ensuring its machinability and reducing cracking during alloy processing. Furthermore, the high-temperature resistant protective coating transforms into a glassy state at high temperatures and adheres to the alloy surface, mitigating oxidation and cracking during forging and reducing surface cooling during transfer from the furnace to the forging anvil. In addition, compared to conventional forging methods, this invention allows for up to 2-3 upsetting and drawing processes per forging pass, with greater forging deformation, sufficient billet deformation, and improved production efficiency.

[0024] 4. This invention follows the principle of fewer passes and larger deformation, employing a rolling method with large plastic deformation. The deformation per single pass is controlled to be 10%–15%, allowing for rapid completion of the rolling process under high-temperature conditions. This improves production efficiency and, through greater plastic deformation, enhances the internal distortion energy of the Ti-Al-Nb alloy hot-rolled sheet microstructure, providing fine-grained material for subsequent heat treatment. Furthermore, by controlling the rolling process parameters and rolling temperature, this invention ensures that the Ti-Al-Nb alloy hot-rolled sheet undergoes significant plastic deformation without localized stress concentration leading to cracking or significant rolling overheating, thus guaranteeing a smooth rolling process and improving yield.

[0025] 5. The high-strength and high-performance Ti-Al-Nb alloy sheet prepared by this invention has a tensile strength Rm≥1050MPa, a yield strength Rp0.2≥900MPa, and an elongation after fracture A≥13% at room temperature, which meets the application requirements of aerospace and other fields such as aerospace engines and rocket propulsion.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the preparation method of the high-strength and ductile Ti-Al-Nb alloy sheet of the present invention.

[0028] Figure 2 The image shows the metallographic structure of the Ti-Al-Nb alloy plate prepared in Example 1 of this invention.

[0029] Figure 3 The image shows the metallographic structure of the Ti-Al-Nb alloy plate prepared in Example 2 of this invention.

[0030] Figure 4 The image shows the metallographic structure of the Ti-Al-Nb alloy plate prepared in Example 3 of this invention.

[0031] Figure 5 The image shows the metallographic structure of the Ti-Al-Nb alloy plate prepared in Example 4 of this invention. Detailed Implementation

[0032] Example 1

[0033] like Figure 1 As shown, this embodiment includes the following steps:

[0034] Step 1: Forging

[0035] Step 101: Peel and saw the Ti-Al-Nb alloy ingot to obtain a cylindrical Ti-Al-Nb alloy ingot with a diameter of Φ340mm. Apply a high-temperature resistant protective coating to its surface, then place it in a heating furnace and heat it at 100℃ above the phase transformation point for 136 minutes. Immediately remove it from the furnace and perform a single-fire forging on a high-speed forging mill. The deformation method is two upsetting and two drawing, with the upsetting and drawing deformation amount being 125%. After forging, air cool it to obtain a single-fire forged billet with a side length × length of □300mm × Lmm. The Ti-Al-Nb alloy ingot is composed of the following composition by mass percentage: Al 13%, Nb 35%, Mo 0.8%, N≤0.03%, H≤0.01%, O≤0.15%, with the balance being Ti and unavoidable impurities.

[0036] Step 102: Apply a high-temperature resistant protective coating to the surface of the forged billet obtained in Step 101, then place it in a heating furnace and heat it at 100°C above the phase transformation point for 180 minutes. Immediately remove it from the furnace and perform re-forging above the phase transformation point on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 125%. After forging, air cool it to obtain the first re-forged billet with a side length × length of □300mm × Lmm.

[0037] Step 103: Apply a high-temperature resistant protective coating to the surface of the first modified forging billet obtained in step 102, then place it in a heating furnace and heat it at 20°C below the phase transformation point for 180 minutes. Immediately remove it from the furnace and perform modified forging below the phase transformation point on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 125%. After forging, air cool it to obtain a second modified forging billet with a side length × length of □300mm × Lmm.

[0038] Step 104: Apply a high-temperature resistant protective coating to the surface of the second modified forging billet obtained in step 103, then place it in a heating furnace and heat it at 80°C below the phase transformation point for 180 minutes. Immediately remove it from the furnace and forge the billet on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 125%. After forging, air cool it to obtain a Ti-Al-Nb forged billet.

[0039] Step 2: Hot rolling

[0040] The Ti-Al-Nb forged slab obtained in step 104 is subjected to milling to remove surface defects, and a high-temperature resistant protective coating is brushed onto the surface. After the protective coating dries completely, it is placed in a heating furnace and heated and held at 1020℃ for 120 minutes. It is then immediately removed from the furnace and rolled into a sheet. The sheet is rolled in one pass in one direction, with a deformation of 60% in one pass and a deformation of 10% in a single pass, to obtain a Ti-Al-Nb alloy hot-rolled sheet with a thickness × width × length of δ30mm × 423mm × Lmm.

[0041] Step 3: Heat Treatment

[0042] The hot-rolled Ti-Al-Nb alloy sheet obtained in step two was solution treated in an atmospheric annealing furnace at 900℃ for 90 min, then air-cooled after being removed from the furnace, and then aged at 650℃ for 8 h, and air-cooled after being removed from the furnace to obtain the Ti-Al-Nb alloy sheet.

[0043] The Ti-Al-Nb alloy sheet prepared in this embodiment has a tensile strength Rm = 1147 MPa, a yield strength Rp0.2 = 984 MPa, and an elongation after fracture A = 17% at room temperature, as determined by testing.

[0044] Figure 2 The image shows the metallographic structure of the Ti-Al-Nb alloy plate prepared in this embodiment. Figure 2 It can be seen that the microstructure of the heat-treated Ti-Al-Nb alloy plate consists of α2 phase, O phase and matrix phase, and the microstructure is uniform.

[0045] Example 2

[0046] like Figure 1 As shown, this embodiment includes the following steps:

[0047] Step 1: Forging

[0048] Step 101: Peel and saw the Ti-Al-Nb alloy ingot to obtain a cylindrical Ti-Al-Nb alloy ingot with a diameter of Φ330mm. Apply a high-temperature resistant protective coating to its surface, then place it in a heating furnace and heat it at 150℃ above the phase transformation point for 230 minutes. Immediately remove it from the furnace and perform a single-fire forging on a high-speed forging mill. The deformation method is two upsetting and two drawing, with the upsetting and drawing deformation amount being 130%. After forging, air cool it to obtain a single-fire forged billet with a side length × length of □300mm × Lmm. The Ti-Al-Nb alloy ingot is composed of the following composition by mass percentage: Al 14%, Nb 38%, Mo 1.0%, N≤0.03%, H≤0.01%, O≤0.15%, with the balance being Ti and unavoidable impurities.

[0049] Step 102: Apply a high-temperature resistant protective coating to the surface of the forged billet obtained in Step 101, then place it in a heating furnace and heat it at 100°C above the phase transformation point for 180 minutes. Immediately remove it from the furnace and perform re-forging above the phase transformation point on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 138%. After forging, air cool it. Repeat the heating, holding, upsetting and drawing forging, and air cooling process once to obtain the first re-forged billet with a side length × length of □300mm × Lmm.

[0050] Step 103: Apply a high-temperature resistant protective coating to the surface of the first modified forging billet obtained in step 102, then place it in a heating furnace and heat it at 40°C below the phase transformation point for 180 minutes. Immediately remove it from the furnace and perform modified forging below the phase transformation point on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 132%. After forging, air cool it. Repeat the heating and holding process and the upsetting and drawing forging and air cooling process once to obtain a second modified forging billet with a side length × length of □300mm × Lmm.

[0051] Step 104: Apply a high-temperature resistant protective coating to the surface of the second modified forging billet obtained in step 103, then place it in a heating furnace and heat it at 100°C below the phase transformation point for 180 minutes. Immediately remove it from the furnace and forge the billet on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 122%. After forging, air cool it to obtain a Ti-Al-Nb forged billet.

[0052] Step 2: Hot rolling

[0053] The Ti-Al-Nb forged slab obtained in step 104 is subjected to milling to remove surface defects, and a high-temperature resistant protective coating is brushed onto the surface. After the protective coating dries, it is placed in a heating furnace and heated and held at 1020℃ for 120 minutes. It is then immediately taken out of the furnace for plate rolling. The plate rolling is a single-pass unidirectional rolling with a deformation of 80% in one pass and a deformation of 15% in a single pass, to obtain an intermediate hot-rolled plate with a thickness × width × length of δ30mm × 430mm × Lmm.

[0054] The intermediate hot-rolled sheet is polished and coated with a high-temperature resistant protective coating. After the protective coating dries completely, it is placed in a heating furnace and heated and held at 1010℃ for 40 minutes. It is then immediately taken out of the furnace for sheet rolling. The sheet rolling is a single-pass unidirectional rolling with a deformation of 73% in one pass and a deformation of 15% in a single pass, to obtain a Ti-Al-Nb alloy hot-rolled sheet with a thickness × width × length of δ8mm × 430mm × Lmm.

[0055] Step 3: Heat Treatment

[0056] The hot-rolled Ti-Al-Nb alloy sheet obtained in step two was solution treated in an atmospheric annealing furnace at 950℃ for 120 min, then air-cooled after being removed from the furnace, and then aged at 720℃ for 10 h, and air-cooled after being removed from the furnace to obtain the Ti-Al-Nb alloy sheet.

[0057] The Ti-Al-Nb alloy sheet prepared in this embodiment has a tensile strength Rm = 1072 MPa, a yield strength Rp0.2 = 917 MPa, and an elongation after fracture A = 23% at room temperature, as tested.

[0058] Figure 3 The image shows the metallographic structure of the Ti-Al-Nb alloy plate prepared in this embodiment. Figure 3 It can be seen that the microstructure of the heat-treated Ti-Al-Nb alloy plate consists of α2 phase, O phase and matrix phase, and the microstructure is uniform.

[0059] Example 3

[0060] like Figure 1 As shown, this embodiment includes the following steps:

[0061] Step 1: Forging

[0062] Step 101: Peel and saw the Ti-Al-Nb alloy ingot to obtain a cylindrical Ti-Al-Nb alloy ingot with a diameter of Φ330mm. Apply a high-temperature resistant protective coating to its surface, then place it in a heating furnace and heat at 120℃ above the phase transformation point for 180 minutes. Immediately remove it from the furnace and perform a single-fire forging on a high-speed forging mill. The deformation method is two upsetting and two drawing, with the upsetting and drawing deformation amount being 130%. After forging, air cool to obtain a single-fire forged billet with a side length × length of □300mm × Lmm. The Ti-Al-Nb alloy ingot is composed of the following components by mass percentage: Al 13.5%, Nb 37%, Mo 0.9%, N≤0.03%, H≤0.01%, O≤0.15%, with the balance being Ti and unavoidable impurities.

[0063] Step 102: Apply a high-temperature resistant protective coating to the surface of the forged billet obtained in Step 101, then place it in a heating furnace and heat it at 100°C above the phase transformation point for 180 minutes. Immediately remove it from the furnace and perform re-forging above the phase transformation point on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 136%. After forging, air cool it to obtain the first re-forged billet with a side length × length of □300mm × Lmm.

[0064] Step 103: Apply a high-temperature resistant protective coating to the surface of the first modified forging billet obtained in step 102, then place it in a heating furnace and heat it at 30°C below the phase transformation point for 180 minutes. Immediately remove it from the furnace and perform modified forging below the phase transformation point on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 128%. After forging, air cool it. Repeat the heating, holding and modified forging below the phase transformation point and air cooling process once to obtain a second modified forging billet with a side length × length of □300mm × Lmm.

[0065] Step 104: Apply a high-temperature resistant protective coating to the surface of the second modified forging billet obtained in step 103, then place it in a heating furnace and heat it at 90°C below the phase transformation point for 180 minutes. Immediately remove it from the furnace and forge it on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 130%. After forging, air cool it to obtain a Ti-Al-Nb forged billet.

[0066] Step 2: Hot rolling

[0067] The Ti-Al-Nb forged slab obtained in step 104 is subjected to milling to remove surface defects, and a high-temperature resistant protective coating is brushed onto the surface. After the protective coating dries completely, it is placed in a heating furnace and heated and held at 1000℃ for 120 minutes. It is then immediately removed from the furnace and rolled into a sheet. The sheet is rolled in one pass in one direction, with a deformation of 70% in one pass and a deformation of 12.5% ​​in a single pass, to obtain a Ti-Al-Nb alloy hot-rolled sheet with a thickness × width × length of δ30mm × 430mm × Lmm.

[0068] Step 3: Heat Treatment

[0069] The hot-rolled Ti-Al-Nb alloy sheet obtained in step two was solution treated in an atmospheric annealing furnace at 925℃ for 105 min, then air-cooled after being removed from the furnace, and then aged at 700℃ for 9 h. After being air-cooled again, the Ti-Al-Nb alloy sheet was obtained.

[0070] The Ti-Al-Nb alloy sheet prepared in this embodiment has a tensile strength Rm = 1065 MPa, a yield strength Rp0.2 = 910 MPa, and an elongation after fracture A = 19% at room temperature, as determined by testing.

[0071] Figure 4 The image shows the metallographic structure of the Ti-Al-Nb alloy plate prepared in this embodiment. Figure 4 It can be seen that the microstructure of the heat-treated Ti-Al-Nb alloy plate consists of α2 phase, O phase and matrix phase, and the microstructure is uniform.

[0072] Example 4

[0073] like Figure 1 As shown, this embodiment includes the following steps:

[0074] Step 1: Forging

[0075] Step 101: Peel and saw the Ti-Al-Nb alloy ingot to obtain a cylindrical Ti-Al-Nb alloy ingot with a diameter of Φ330mm. Apply a high-temperature resistant protective coating to its surface, then place it in a heating furnace and heat it at 120℃ above the phase transformation point for 180 minutes. Immediately remove it from the furnace and perform a single-fire forging on a high-speed forging mill. The deformation method is two upsetting and two drawing, with the upsetting and drawing deformation amount being 130%. After forging, air cool it to obtain a single-fire forged billet with a side length × length of Φ300mm × Lmm. The Ti-Al-Nb alloy ingot is composed of the following composition by mass percentage: Al 13.8%, Nb 36%, Mo 0.85%, N≤0.03%, H≤0.01%, O≤0.15%, with the balance being Ti and unavoidable impurities.

[0076] Step 102: Apply a high-temperature resistant protective coating to the surface of the forged billet obtained in Step 101, then place it in a heating furnace and heat it at 100°C above the phase transformation point for 180 minutes. Immediately remove it from the furnace and perform re-forging above the phase transformation point on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 136%. After forging, air cool it. Repeat the heating, holding and re-forging above the phase transformation point and air cooling process once to obtain the first re-forged billet with a side length × length of □300mm × Lmm.

[0077] Step 103: Apply a high-temperature resistant protective coating to the surface of the first modified forging billet obtained in step 102, then place it in a heating furnace and heat it at 25°C below the phase transformation point for 180 minutes. Immediately remove it from the furnace and perform modified forging below the phase transformation point on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 128%. After forging, air cool it to obtain a second modified forging billet with a side length × length of □300mm × Lmm.

[0078] Step 104: Apply a high-temperature resistant protective coating to the surface of the second modified forging billet obtained in step 103, then place it in a heating furnace and heat it at 85°C below the phase transformation point for 180 minutes. Immediately remove it from the furnace and forge the billet on a high-speed forging machine. The deformation method is two upsetting and two drawing, and the deformation amount of upsetting and drawing forging is 128%. After forging, air cool it to obtain a Ti-Al-Nb forged billet.

[0079] Step 2: Hot rolling

[0080] The Ti-Al-Nb forged slab obtained in step 104 is subjected to milling to remove surface defects, and a high-temperature resistant protective coating is brushed onto the surface. After the protective coating dries completely, it is placed in a heating furnace and heated and held at 1000℃ for 120 minutes. It is then immediately removed from the furnace and rolled into a sheet. The sheet is rolled in one pass in one direction, with a deformation of 65% in one pass and a deformation of 14% in a single pass, to obtain a Ti-Al-Nb alloy hot-rolled sheet with a thickness × width × length of δ35mm × 430mm × Lmm.

[0081] Step 3: Heat Treatment

[0082] The hot-rolled Ti-Al-Nb alloy sheet obtained in step two was solution treated in an atmospheric annealing furnace at 940℃ for 110 min, then air-cooled after being removed from the furnace, and then aged at 680℃ for 10 h, and air-cooled after being removed from the furnace to obtain the Ti-Al-Nb alloy sheet.

[0083] The Ti-Al-Nb alloy sheet prepared in this embodiment has a tensile strength Rm = 1165 MPa, a yield strength Rp0.2 = 950 MPa, and an elongation after fracture A = 18% at room temperature, as tested.

[0084] Figure 5 The image shows the metallographic structure of the Ti-Al-Nb alloy plate prepared in this embodiment. Figure 5 It can be seen that the microstructure of the heat-treated Ti-Al-Nb alloy plate consists of α2 phase, O phase and matrix phase, and the microstructure is uniform.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for producing a high-strength plastic Ti-Al-Nb alloy sheet for aerospace vehicles, characterized by, The method comprises the following steps: Step one, forging Step 101, the Ti-Al-Nb alloy ingot is subjected to skinning and sawing treatment, then heated and kept at 100-150 DEG C above the phase transition point, after discharging, one-heat blooming forging is carried out on a fast forging machine, after forging, air cooling is carried out, and a one-heat forged blank is obtained; Step 102, the one-heat forged blank obtained in step 101 is heated and kept at 100 DEG C above the phase transition point, after discharging, above-phase transition point re-forging is carried out on a fast forging machine, after forging, air cooling is carried out, and a first re-forged blank is obtained; The above-phase transition point re-forging is completed in 1-2 heats; Step 103, the first re-forged blank obtained in step 102 is heated and kept at 20-40 DEG C below the phase transition point, after discharging, below-phase transition point re-forging is carried out on a fast forging machine, after forging, air cooling is carried out, and a second re-forged blank is obtained; The below-phase transition point re-forging is completed in 1-2 heats; Step 104, the second re-forged blank obtained in step 103 is heated and kept at 80-100 DEG C below the phase transition point, after discharging, slab forging is carried out on a fast forging machine, after forging, air cooling is carried out, and a Ti-Al-Nb forged slab is obtained; In the forging process, the deformation mode of each heat forging is two upsetting and two drawing, and the deformation amount of each heat forging is more than 115%; Step two, hot rolling The surface of the Ti-Al-Nb forged slab obtained in step 104 is brushed with high-temperature-resistant protective paint, after the protective paint is dry, it is loaded into a heating furnace for heating and keeping, after discharging, slab rolling is carried out, and a Ti-Al-Nb alloy hot-rolled plate is obtained; The slab rolling is completed in 1-2 heats according to the target thickness of the Ti-Al-Nb alloy hot-rolled plate; The rolling is single-direction rolling, and the deformation amount of each heat is 60%-80%, and the single-pass deformation amount is 10%-15%; Step three, heat treatment The Ti-Al-Nb alloy hot-rolled plate obtained in step two is subjected to solid solution treatment by an air furnace, and then is subjected to aging treatment, and a high-strength plastic Ti-Al-Nb alloy plate is obtained; The solid solution treatment temperature is 900-950 DEG C, and the holding time is 90-120 min; The aging treatment temperature is 650-720 DEG C, the holding time is 8-10 h, and the cooling mode is air cooling; The tensile strength Rm of the high-strength plastic Ti-Al-Nb alloy plate is greater than or equal to 1050 MPa, the yield strength Rp0.2 is greater than or equal to 900 MPa, and the elongation A after fracture is greater than or equal to 13%.

2. The method of claim 1, wherein the method is characterized by: The Ti-Al-Nb alloy ingot in step 101 is composed of the following mass percentage components: Al 13%-14%, Nb 35%-38%, Mo 0.8%-1.0%, N≤0.03%, H≤0.01%, O≤0.15%, and the balance is Ti and unavoidable impurities.

3. The method for preparing a high-strength, ductile Ti-Al-Nb alloy sheet for aerospace vehicles according to claim 1, characterized in that, In step one, high-temperature-resistant protective paint is brushed on the surface of the forging object before each heat forging.

4. The method of claim 1, wherein the method is characterized by: In the forging process in step one, the heating and holding time of the first open-die forging is 0.4-0.7 times the diameter of the cylindrical Ti-Al-Nb alloy ingot, and the heating and holding time of the remaining open-die forging is 0.6 times the thickness of the corresponding processed forging blank, and the unit of the heating and holding time is min, and the units of the diameter and thickness are mm.

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