A superplastic high-strength aluminum alloy fine-grained plate and preparation method thereof
By introducing hard phase pinning grain boundary and subgrain boundary structures and combining isothermal rolling technology, the environmental pollution and grain unevenness of traditional alloy sheets are solved, and high-strength and high-plastic superplastic aluminum alloy fine crystals are achieved. The preparation of plates is suitable for the manufacturing of integrally formed parts in the aerospace field.
Patent Information
- Application Number
- CN202310434052.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-04-21
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2043-04-21
AI Technical Summary
In the preparation process of traditional Al-Zn-Mg-Cu alloy superplastic plates, salt bath annealing leads to environmental pollution, uneven grain structure, and the steering rolling process is limited by the plate size, which leads to defects such as edge cracks, which affects the alloy superplastic Performance.
By introducing hard phase pinning grain boundaries, subgrain boundaries and dislocation structures with good high temperature stability, composite microalloyation and isothermal rolling technology, and conventional air furnaces replace salt bath furnaces, achieving uniform deformation of the plate along the thickness direction is achieved by using a conventional air furnace. and grain tissue uniformity.
The preparation of superplastic high-strength aluminum alloy fine crystal panels is realized, reducing the dependence of recrystallization annealing on high temperature rise rate, reducing environmental pollution, and improving the mechanical and plastic properties of the panels.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of alloy material processing, and in particular relates to a superplastic high-strength aluminum alloy fine-grained plate and a preparation method thereof. Background Art
[0002] Al-Zn-Mg-Cu alloys are ultra-high strength deformable aluminum alloys with high strength, good hot working properties, good fracture toughness and corrosion resistance. They are widely used in aerospace, rail transit, bridge construction, national defense and military industries, and play an extremely important role in industrial production.
[0003] The aerospace field is in urgent need of integrally formed parts with excellent performance. Superplastic forming, as a material manufacturing technology, has the characteristics of "large deformation, low stress, and easy forming". It can achieve less or no cutting processing and forming. It is suitable for manufacturing aluminum alloy thin-walled integral components. It can reduce the number of parts, reduce costs, improve the overall stiffness and reliability of parts, and extend the service life of aircraft. It has significant economic benefits and important strategic significance.
[0004] The traditional preparation process of Al-Zn-Mg-Cu alloy superplastic sheet is solid solution-aging-rolling-salt bath recrystallization annealing, but there are several problems in the preparation of superplastic sheet using this process:
[0005] (1) The coarse η(MgZn2) phase formed by overaging of Al-Zn-Mg-Cu alloys is very easy to soften at high temperatures. It is necessary to use a salt bath furnace to quickly heat up to the recrystallization temperature to suppress the release of excessive deformation energy due to the softening of the η(MgZn2) phase during the heating process, increase the recrystallization nucleation rate, and refine the grains. However, the size of the plate annealed in the salt bath is limited by the size of the salt bath furnace. There are few large salt bath furnaces in China, and the waste gas and waste residue generated by the salt bath destroy the ecological balance and pollute water resources, which is not conducive to energy conservation and environmental protection.
[0006] (2) During the rolling process, the plate has uneven deformation along the thickness direction. The surface of the plate is subjected to more shear deformation. At the same time, the surface of the plate is in contact with the roller and the air, and the heat dissipation speed is faster, resulting in a lower actual deformation temperature of the surface. Since large shear deformation and low rolling deformation temperature are key factors in improving deformation energy storage, the surface of the plate accumulates higher deformation energy storage. In the final recrystallization annealing process, the nucleation rate of the surface layer is higher than that of the center layer. The prepared superplastic plate shows the characteristics of uneven grain structure along the thickness direction. The grain size of the surface layer is significantly smaller than that of the center layer, which affects the coordinated deformation of the organization during the superplastic forming process and is not conducive to the performance of the superplastic properties of the alloy.
[0007] In addition, the Chinese patent with authorization announcement number CN108034909B and the Chinese patent with publication number CN103882351A have successfully achieved the preparation of superplastic plates. However, due to the use of a steering rolling process, large-size plates are limited by their large size and heavy weight, making it difficult to rotate on the roller. In addition, the long residence time during the steering process causes the plate temperature to drop, which can easily cause defects such as edge cracks, resulting in poor plate quality.
[0008] Therefore, how to ensure the mechanical properties of superplastic alloy sheets while improving their plasticity is the key to the application of this series of aluminum alloys. Summary of the invention
[0009] In view of the technical problems existing in the prior art, the present invention proposes a superplastic high-strength aluminum alloy fine-grained plate. Through composite microalloying, a hard phase with good stability at high temperature is introduced to pin grain boundaries, subgrain boundaries and dislocation structures, thereby inhibiting the release of deformation energy storage during the heating process, thereby getting rid of the dependence of recrystallization annealing on high heating rate.
[0010] In addition, the present invention also proposes a method for preparing the superplastic high-strength aluminum alloy fine-grained plate, which uses a conventional air furnace instead of a salt bath furnace, and adopts an isothermal rolling process. Through the coordination of the billet and roller temperature and the rolling process, the plate is uniformly deformed along the thickness direction, and the surface and the core accumulate the same deformation energy storage, thereby realizing the preparation of a superplastic plate with uniform grain structure.
[0011] Based on the above purpose, the present invention adopts the following technical solutions:
[0012] A superplastic high-strength aluminum alloy fine-grained plate. The aluminum alloy is prepared by aluminum alloy ingots. The aluminum alloy ingots are composed of the following components in percentage by mass: zinc: 4.2-6.8%, magnesium: 1.6-2.7%, copper: 1.0-2.1%, chromium: 0.10-0.35%, scandium: 0.10-0.35%, zirconium: 0.05-0.30%, silver: 0.10-0.35%, erbium: 0.05-0.25%, yttrium: 0.05-0.15%, and the balance is aluminum.
[0013] Further preferably, the aluminum alloy ingot is composed of the following components in mass percentage: zinc: 5.4-6.4%, magnesium: 1.6-2.3%, copper: 1.3-2.0%, chromium: 0.15-0.30%, scandium: 0.10-0.35%, zirconium: 0.05-0.30%, silver: 0.10-0.35%, erbium: 0.05-0.25%, yttrium: 0.05-0.15%, and the balance is aluminum.
[0014] The method for preparing the superplastic high-strength aluminum alloy fine-grained plate comprises the following steps:
[0015] (1) Preparation of ingot: The raw materials are prepared according to the mass percentage of each component in the aluminum alloy, and the prepared raw materials are placed in a vacuum medium frequency induction melting furnace and melted at 700-820° C., and the obtained molten metal is refined in an argon atmosphere at 730-750° C. for 10-20 min. After refining, the molten metal is allowed to stand at 730-750° C. for 10-20 min, and then cast to obtain an ingot;
[0016] (2) Annealing treatment: subjecting the ingot obtained in step (1) to a two-stage homogenization annealing to eliminate micro-component segregation and obtain a homogeneous ingot;
[0017] (3) Forging: After removing the surface oxide layer of the ingot after homogenization treatment in step (2), preheat to 380-420°C, keep warm for 4-8 hours, forge the blank, adopt the three-upsetting and three-drawing forging process, the forging ratio is 1.5-1.9, and forge in one fire without tempering in the middle;
[0018] (4) hot rolling: after removing the surface oxide layer of the forging obtained in step (3), hot rolling is performed after keeping the temperature at 400-440° C. for 4-6 hours to obtain a hot-rolled plate blank;
[0019] (5) Solution treatment: the plate blank obtained in step (4) is kept at 460-530° C. for 2-4 h, and then water quenched;
[0020] (6) Strong aging treatment: The plate blank of step (5) is kept at 360-440°C for 8-24h, and then air-cooled to room temperature.
[0021] Specifically, in step (2), the double-stage homogenization annealing process is: the first stage homogenization degradation treatment is 430-450° C. for 12-36 hours, the second stage homogenization degradation treatment is 460-480° C. for 12-36 hours, and then air-cooled or water-cooled to room temperature.
[0022] Specifically, during hot rolling in step (4), the reduction in a single pass is 20 to 30%.
[0023] Specifically, in step (4), hot rolling is performed to obtain a hot-rolled plate blank with a size of 1000*1000*20 mm.
[0024] Specifically, during the water quenching in step (5), the water temperature is 40-55°C.
[0025] Further, the plate after the solution treatment and aging treatment in step (6) is subjected to isothermal rolling, wherein the isothermal rolling is specifically as follows:
[0026] The plate blank is heated to 100-300°C and kept warm for 2-4 hours. At the same time, the rollers are heated to 100-300°C using a thermal oil furnace to ensure isothermal rolling when the material temperature and roller temperature are consistent.
[0027] Specifically, the reduction amount of the isothermal rolling pass is 5 to 30%.
[0028] Specifically, after isothermal rolling, a warm-rolled plate with a size of 2000*1000*(1-3) mm is obtained.
[0029] Further, the isothermally rolled plate is subjected to recrystallization annealing, wherein the recrystallization annealing is specifically as follows:
[0030] The plate is kept at 460-500° C. for 10-90 minutes in an air furnace for recrystallization annealing to obtain a superplastic fine-grained plate with a size of 2000*1000*(1-3) mm.
[0031] Specifically, in the preparation method of the present invention, the raw materials include high-purity aluminum (≥99.996%), pure zinc (≥99.95%), pure magnesium (≥99.95%), pure copper (≥99.99%) and AlAg40, AlCr5, AlSc2, AlZr10, AlY10, and AlEr5 intermediate alloys.
[0032] The above method obtains an ingot by smelting and casting, and then performs homogenization annealing, forging and rolling on the ingot to finally obtain a superplastic high-strength aluminum alloy fine-grained plate.
[0033] The present invention also proposes the application of the superplastic high-strength aluminum alloy fine-grained plate in the manufacture of parts in the aerospace field.
[0034] Specifically, the superplastic high-strength aluminum alloy fine-grained plate can be used to manufacture aircraft air intake lip frames, which can achieve integrated forming and reduce riveting processes; it can also be used to manufacture maintenance doors for large passenger aircraft, which can reduce the number of parts to 1 / 5 and reduce the use of rivets; in addition, it can also be used to manufacture astronaut helmets on spacecraft.
[0035] Compared with the prior art, the present invention has the following beneficial effects:
[0036] 1. The present invention introduces Al3Sc, Al3(Sc by adding microalloying elements Sc and Zr. x ,Zr 1-x ), Al3Zr and other hard and heat-resistant phases can serve as heterogeneous nucleation cores to increase the nucleation rate, while pinning grain boundaries to inhibit grain growth and refine the alloy casting structure.
[0037] 2. The present invention also uses a strong aging process to guide the MgZn2 phase and Al3Sc, Al3(Sc x ,Zr 1-x), Al3Zr and other heat-resistant phases continue to precipitate and coarsen, and a strong strain zone is formed around the coarse MgZn2 phase during the rolling process, retaining extremely high deformation energy storage. During the recrystallization annealing heating process, the heat-resistant phases pin the grain boundaries, subgrain boundaries and dislocation structures, inhibiting the release of deformation energy storage, and rapidly recrystallizing when the recrystallization temperature is reached to obtain a fine-grained structure. This reduces the requirement for high heating rate of recrystallization annealing. In order to get rid of the limitation of salt bath, the process of the present invention can use a conventional air furnace for recrystallization annealing, reducing the pollution to the environment during the production process.
[0038] 3. The present invention utilizes a heat transfer oil heating system to heat the rollers, ensuring that the material temperature and the roller temperature are consistent, so that the surface and core temperatures of the plate are close during the rolling process. At the same time, the plate is uniformly deformed along the thickness direction through a large amount of reduction, which promotes the uniform distribution of deformation energy storage in the thickness direction, and finally realizes the preparation of superplastic plates with uniform grain structure.
[0039] 4. The present invention reduces the requirement of high heating rate for recrystallization annealing through the process of "microalloying + isothermal rolling", and at the same time realizes uniform deformation of the plate, thus successfully preparing superplastic high-strength aluminum alloy fine-grained plate.
[0040] The superplastic Al-Zn-Mg-Cu series high-strength aluminum alloy plate material involved in the present invention has simple process flow, low cost, high comprehensive mechanical properties and good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS
[0041] Figure 1 The metallographic image of the superplastic fine-grained plate obtained in step (8) of Example 1;
[0042] Figure 2 These are photos of Examples 1 to 3 and the comparative example samples after stretching. DETAILED DESCRIPTION
[0043] In order to make the technical purpose, technical scheme and beneficial effects of the present invention clearer, the technical scheme of the present invention is further described below in conjunction with specific embodiments, but the embodiments are intended to explain the present invention and cannot be understood as limiting the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in the field or the product instructions are followed. The raw materials used in the following embodiments are all common commercially available products.
[0044] Example 1
[0045] A superplastic Al-Zn-Mg-Cu series high-strength aluminum alloy fine-grained plate, wherein the aluminum alloy is prepared by aluminum alloy ingots, and the aluminum alloy ingots are composed of the following components in percentage by mass: zinc: 5.7%, magnesium: 2.3%, copper: 1.6%, chromium: 0.22%, scandium: 0.20%, zirconium: 0.10%, silver: 0.20%, erbium: 0.15%, yttrium: 0.10%, and the balance is aluminum.
[0046] The preparation method of the superplastic high-strength aluminum alloy fine-grained plate comprises the processes of melting, deterioration treatment, forging, rolling and the like, wherein the aluminum element, zinc element, magnesium element and copper element are respectively added in the form of high-purity aluminum (≥99.996%), pure zinc (≥99.95%), pure magnesium (≥99.95%) and pure copper (≥99.99%); the Ag, Cr, Sc, Zr, Y and Er used are respectively added in the form of AlAg40, AlCr5, AlSc2, AlZr10, AlY10 and AlEr5 master alloys, and the specific steps are as follows:
[0047] (1) Preparation of ingot: The raw materials are prepared according to the mass percentage of each component in the aluminum alloy, and the prepared raw materials are placed in a vacuum medium frequency induction melting furnace and melted at 700° C., and the obtained molten metal is refined at 750° C. in an argon atmosphere for 10 min. After refining, the molten metal is allowed to stand at 750° C. for 20 min, and then cast to obtain an ingot;
[0048] (2) Annealing treatment: subjecting the ingot obtained in step (1) to a double-stage homogenization annealing to obtain a homogeneous ingot; wherein the double-stage homogenization annealing process is: the first stage homogenization degradation treatment is 440° C. for 24 hours, the second stage homogenization degradation treatment is 470° C. for 24 hours, and then air-cooled to room temperature;
[0049] (3) Forging: After removing the surface oxide layer of the ingot after homogenization treatment in step (2), preheat to 400°C, keep the temperature for 6 hours, forge the blank, adopt the three-upsetting and three-drawing forging process, the forging ratio is 1.7, and the ingot is forged in one fire without tempering in the middle;
[0050] (4) hot rolling: after removing the surface oxide layer of the forging obtained in step (3), hot rolling is performed at 420° C. for 6 h, with a single-pass reduction of 25% to obtain a hot-rolled sheet blank with a thickness of 1000*1000*20 mm;
[0051] (5) Solution treatment: the plate blank obtained in step (4) was kept at 490° C. for 3 h and then water quenched;
[0052] (6) Aging treatment: the plate blank obtained in step (5) is kept at 400° C. for 16 h, and then air-cooled to room temperature;
[0053] (7) Isothermal rolling: the plate blank obtained in step (6) is heated to 200° C. and kept at this temperature for 3 h. At the same time, the rollers are heated to 200° C. using a thermal oil furnace. Isothermal rolling is performed while ensuring that the material temperature and the roller temperature are consistent. The single-pass reduction is 17%, and a 2 mm thick plate is obtained.
[0054] (8) Recrystallization annealing: The plate obtained in step (7) is subjected to recrystallization annealing at 480° C. in an air furnace for 60 min to obtain a superplastic fine-grained plate of 2000*1000*2 mm.
[0055] The metallographic image of the superplastic fine-grained plate obtained in step (8) of Example 1 is as follows: Figure 1 As shown, from Figure 1 It can be seen that the grain structure of the plate is uniform and fine.
[0056] Example 2
[0057] A superplastic Al-Zn-Mg-Cu series high-strength aluminum alloy fine-grained plate, wherein the aluminum alloy is prepared by aluminum alloy ingots, and the aluminum alloy ingots are composed of the following components in percentage by mass: zinc: 5.7%, magnesium: 2.3%, copper: 1.6%, chromium: 0.22%, scandium: 0.20%, zirconium: 0.10%, silver: 0.20%, erbium: 0.15%, yttrium: 0.10%, and the balance is aluminum.
[0058] The method for preparing the superplastic high-strength aluminum alloy fine-grained plate in Example 2 is different from that in Example 1 in that:
[0059] In step (7), the rollers are not preheated before isothermal rolling, and isothermal rolling is directly performed; in addition, no recrystallization annealing is performed after isothermal rolling.
[0060] Example 3
[0061] A superplastic Al-Zn-Mg-Cu series high-strength aluminum alloy fine-grained plate, wherein the aluminum alloy is prepared by aluminum alloy ingots, and the aluminum alloy ingots are composed of the following components in percentage by mass: zinc: 5.7%, magnesium: 2.3%, copper: 1.6%, chromium: 0.22%, silver: 0.20%, erbium: 0.15%, yttrium: 0.10%, and the balance is aluminum.
[0062] The preparation method of the superplastic high-strength aluminum alloy fine-grained plate in Example 3 is the same as that in Example 1.
[0063] Comparative Example 1
[0064] Comparative Example 1 discloses a method for preparing a 7075 aluminum alloy, wherein the 7075 aluminum alloy is composed of the following components in percentage by mass: zinc: 5.6%, magnesium: 2.5%, copper: 1.6%, chromium: 0.23%, and the balance is aluminum.
[0065] The preparation method of the 7075 aluminum alloy comprises the following specific steps:
[0066] (1) Preparation of ingot: The raw materials are prepared according to the mass percentage of each component in the aluminum alloy, and the prepared raw materials are placed in a vacuum medium frequency induction melting furnace and melted at 730° C., and the obtained molten metal is refined in an argon atmosphere at 750° C. for 20 min. After refining, the molten metal is allowed to stand at 750° C. for 20 min, and then cast to obtain an ingot;
[0067] (2) Annealing treatment: subjecting the ingot obtained in step (1) to a double-stage homogenization annealing to obtain a homogeneous ingot; wherein the double-stage homogenization annealing process is: the first stage homogenization degradation treatment is 440° C. for 24 hours, the second stage homogenization degradation treatment is 470° C. for 24 hours, and then air-cooled to room temperature;
[0068] (3) Forging: After removing the surface oxide layer of the ingot after homogenization treatment in step (2), preheat to 400°C, keep the temperature for 6 hours, forge the blank, adopt the three-upsetting and three-drawing forging process, the forging ratio is 1.7, and the ingot is forged in one fire without tempering in the middle;
[0069] (4) hot rolling: after removing the surface oxide layer of the forging obtained in step (3), hot rolling is performed at a temperature of 420° C. with a single-pass reduction of 25% to obtain a hot-rolled plate with a thickness of 2000*1000*2 mm;
[0070] (5) Recrystallization annealing: The plate obtained in step (4) is subjected to recrystallization annealing at 480° C. for 60 min in an air furnace to obtain a superplastic fine-grained plate of 2000*1000*2 mm.
[0071] Performance Testing
[0072] The superplastic properties of the samples (superplastic plates prepared in Examples 1 to 3 and the product of Comparative Example 1) were tested using a RWS50 stretching machine equipped with a split three-section resistance wire heating furnace. Three parallel samples were tested in each state and the average value was taken. The superplastic test was carried out in accordance with the test method in the Theory of Superplastic Deformation of Metals.
[0073] The room temperature mechanical properties test was carried out in accordance with the provisions of GB / T 228. The sample was stretched on an MTS Landmark electro-hydraulic servo testing machine. The stretching direction was along the rolling direction of the sample. An extensometer was added during the stretching process to more accurately measure the deformation. The chuck moving speed was 2 mm / min. Three parallel samples were tested in each state and the average value was taken. The properties of the aluminum alloy sheets obtained in the embodiment and the comparative example are shown in Table 1.
[0074] Figure 2 The following are photos of the samples of Example 1, Example 2, Example 3 and Comparative Example 1 after superplastic stretching.
[0075] Table 1 Summary of properties of superplastic plates of examples and comparative examples
[0076]
[0077]
[0078] From Table 1 and Figure 2 It can be seen that the superplastic sheet prepared by the present invention has a -4 s -1 Under the initial strain rate conditions, the maximum elongation can reach 860%, and the room temperature tensile strength is as high as 608MPa. It is suitable for manufacturing thin-walled integral components or aerospace skins used in the aerospace field and has broad application prospects.
[0079] The above describes the specific implementation examples of the present invention. It should be understood that the present invention is not limited to the above specific implementation examples. Those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.
Claims
1. A superplastic high-strength aluminum alloy fine-grained plate, characterized in that: The aluminum alloy is prepared by aluminum alloy ingot, and the aluminum alloy ingot is composed of the following components in percentage by mass: Composition: Zinc: 4.2~6.8%, Magnesium: 1.6~2.7%, Copper: 1.0~2.1%, Chromium: 0.10~0.35%, Scandium: 0.10~0.35%, Zirconium: 0.05~0.30%, Silver: 0.10~0.35%, Erbium: 0.05~0.25%, Yttrium: 0.05~0.15%, the balance is aluminum; The method for preparing the superplastic high-strength aluminum alloy fine-grained plate comprises the following steps: (1) Preparation of ingot: The raw materials are prepared according to the mass percentage of each component in the aluminum alloy, and the prepared raw materials are placed in a vacuum medium frequency induction melting furnace and melted at 700-820°C, and the obtained molten metal is refined in an argon atmosphere at 730-750°C for 10-20 minutes. After refining, the molten metal is allowed to stand at 730-750°C for 10-20 minutes, and then cast to obtain an ingot; (2) Annealing treatment: subjecting the ingot obtained in step (1) to a double-stage homogenization annealing to obtain a homogeneous ingot; (3) Forging: After removing the surface oxide layer of the ingot after homogenization treatment in step (2), preheat it to 380-420°C, keep it warm for 4-8 hours, forge it into a blank, adopt a three-upsetting and three-drawing forging process, the forging ratio is 1.5-1.9, and it is forged in one fire without tempering in the middle; (4) hot rolling: after removing the surface oxide layer of the forging obtained in step (3), hot rolling is performed after keeping the temperature at 400-440°C for 4-6 hours to obtain a hot-rolled plate blank; (5) Solution treatment: the plate blank obtained in step (4) is kept at 460-530°C for 2-4 hours, and then water quenched; (6) Strong aging treatment: the sheet blank of step (5) is kept at 360-440°C for 8-24h, and then air-cooled to room temperature; The preparation method further comprises isothermal rolling the plate after the solution treatment and aging treatment in step (6), wherein the isothermal rolling is specifically as follows: The plate blank is heated to 100~300℃ and kept warm for 2~4h. At the same time, the rollers are heated to 100~300℃ using a thermal oil furnace to ensure isothermal rolling when the material temperature and roller temperature are consistent.
2. The superplastic high-strength aluminum alloy fine-grained plate according to claim 1, characterized in that: The aluminum alloy ingot is composed of the following components in percentage by mass: Composition: Zinc: 5.4~6.4%, Magnesium: 1.6~2.3%, Copper: 1.3~2.0%, Chromium: 0.15~0.30%, Scandium: 0.10~0.35%, Zirconium: 0.05~0.30%, Silver: 0.10~0.35%, Erbium: 0.05~0.25%, Yttrium: 0.05~0.15%, and the balance is aluminum.
3. The superplastic high-strength aluminum alloy fine-grained plate according to claim 1 or 2, characterized in that: In step (2), the double-stage homogenization annealing process is as follows: the first stage homogenization degradation treatment is 430-450°C for 12-36 hours, the second stage homogenization degradation treatment is 460-480°C for 12-36 hours, and then air-cooled or water-cooled to room temperature.
4. The superplastic high-strength aluminum alloy fine-grained plate according to claim 1 or 2, characterized in that: During hot rolling in step (4), the reduction per pass is 20-30%.
5. The superplastic high-strength aluminum alloy fine-grained plate according to claim 1 or 2, characterized in that: During the water quenching in step (5), the water temperature is 40-55°C.
6. The superplastic high-strength aluminum alloy fine-grained plate according to claim 1 or 2, characterized in that: The isothermal rolling pass reduction is 5-30%.
7. The superplastic high-strength aluminum alloy fine-grained plate according to claim 1 or 2, characterized in that: The isothermally rolled plate is subjected to recrystallization annealing, wherein the recrystallization annealing is specifically as follows: The plate is kept at 460-500°C for 10-90 minutes for recrystallization annealing to obtain a superplastic fine-grained plate.
8. Application of the superplastic high-strength aluminum alloy fine-grained plate according to claim 1 or 2 in the manufacture of parts in the aerospace field.