High-strength, high-toughness and high-formability 5XCT3 aluminum alloy plate and preparation method thereof

Abstract

The invention belongs to the technical field of aluminum alloy plate preparation, and particularly relates to a high-strength, high-toughness and high-formability 5XCT3 aluminum alloy plate and a preparation method thereof. The preparation method of the 5XCT3 aluminum alloy plate sequentially comprises the processes of smelting, two-pass hot rolling, cold rolling, intermediate annealing, finish rolling and recrystallization annealing. According to the invention, an aluminum alloy plate with the thickness of 1.0-1.5 mm can be prepared by combining a microalloying process, a short-flow processing process, an intermediate annealing process and a recrystallization annealing process, a second phase in the alloy is distributed in a strip shape along the rolling direction, the Vickers hardness is greater than or equal to 70HV, the tensile strength is greater than or equal to 320MPa, the yield strength is greater than or equal to 190MPa, the elongation is greater than or equal to 23%, and the cupping value is greater than or equal to 7mm; the comprehensive requirements of new energy automobile door plates, automobile body plates and other parts on high strength, high toughness and high formability of the aluminum alloy plate are met, and the aluminum alloy plate has wide application prospects in the field of preparation of new energy automobile lightweight materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloy sheet preparation, and in particular relates to a 5XCT3 aluminum alloy sheet with high strength, high toughness and high formability and a preparation method thereof. Background Art

[0002] Aluminum alloy is the main material for lightweight new energy vehicles. Lightweighting can not only reduce the overall weight of the vehicle, reduce energy consumption during driving, and extend the vehicle's range under the same battery capacity, but also improve the vehicle's acceleration, braking and handling performance, making the vehicle more flexible and agile. Due to factors such as reduced energy consumption, extended battery life and reduced maintenance costs, the overall cost of the vehicle will also be reduced. In addition, lightweighting can reduce energy consumption and greenhouse gas emissions during vehicle production and use, which is very consistent with the requirements of sustainable development.

[0003] Among them, 5XCT3 aluminum alloy has the advantages of low density, light weight, good corrosion resistance and excellent processing performance compared to traditional steel, and is often used as the body inner panel material of new energy vehicles (such as new energy vehicle door panels, body panels, etc.). However, the existing 5XCT3 aluminum alloy sheet is difficult to take into account the comprehensive requirements of the inner panel material for strength, toughness and forming performance, and it is difficult to achieve the best performance balance, and it cannot meet the application demand of new energy vehicle inner panels for high-quality 5XCT3 aluminum alloy sheet. Summary of the invention

[0004] In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a 5XCT3 aluminum alloy sheet with high strength, high toughness and high formability and a preparation method thereof. The present invention combines microalloying, short-process processing technology, intermediate annealing and recrystallization annealing technology to prepare an aluminum alloy sheet with a thickness of 1.0 to 1.5 mm. The second phase in the alloy is distributed in a band along the rolling direction, with a Vickers hardness of ≥70HV, a tensile strength of ≥320MPa, a yield strength of ≥190MPa, an elongation of ≥23%, and a cupping value of ≥7mm, which meets the comprehensive requirements of high strength, high toughness and high formability of aluminum alloy sheets for components such as door panels and body panels of new energy vehicles.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for preparing a 5XCT3 aluminum alloy sheet with high strength, high toughness and high formability comprises the following steps:

[0007] (1) selecting raw materials according to the composition of the 5XCT3 aluminum alloy plate, mixing the raw materials, smelting them, and then pouring them to obtain a plate-shaped aluminum alloy ingot;

[0008] (2) cooling the plate-shaped aluminum alloy ingot obtained in step (1) to 400-450° C., performing two hot rolling processes using the residual heat, then cooling to room temperature, and then performing cold rolling to obtain a cold-rolled aluminum alloy plate;

[0009] (3) performing intermediate annealing on the cold-rolled aluminum alloy sheet, cooling it to room temperature, and then sequentially performing finish rolling and recrystallization annealing to obtain the 5XCT3 aluminum alloy sheet with high strength, high toughness and high formability;

[0010] The composition of the 5XCT3 aluminum alloy plate is: V 0.10%-0.45%, Ni 0.10%-0.30%, Mg 4.2%-4.6%, Mn 0.25%-0.35%, Si 0.02%-0.10%, Fe 0.02%-0.10%, Cr 0.08%-0.35%, Ti 0.05%-0.15%, and the balance is Al and unavoidable impurities; the temperature of the recrystallization annealing treatment is 350-400° C., and the time is 1-3 h.

[0011] As a preferred solution, in step (1), the smelting temperature is 700-800°C.

[0012] As a preferred solution, in step (1), the thickness of the plate-shaped aluminum alloy ingot is 8 to 12 mm.

[0013] As a preferred solution, in step (2), the pressing amount of each hot rolling process is 20% to 35%.

[0014] As a preferred solution, in step (2), the pressing amount of each cold rolling process is 20% to 25%.

[0015] As a preferred solution, in step (2), the thickness of the aluminum alloy sheet after cold rolling is reduced to 2.5 to 3.5 mm.

[0016] As a preferred solution, in step (3), the temperature of the intermediate annealing treatment is 400-450° C., and the holding time is 3-5 hours.

[0017] As a preferred solution, in step (3), the cooling is air cooling.

[0018] As a preferred solution, in step (3), the finishing rolling treatment is to reduce the thickness of the aluminum alloy plate to 1.0-1.5 mm. Further preferably, the finishing rolling treatment is performed at room temperature.

[0019] The high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet is prepared by the above preparation method.

[0020] The technical solution of the present invention has the following advantages and beneficial effects:

[0021] The preparation method of the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet provided by the present invention comprises smelting, two-pass hot rolling, cold rolling, intermediate annealing, finishing rolling and recrystallization annealing processes in sequence. The present invention can prepare an aluminum alloy sheet with a thickness of 1 to 1.5 mm by combining microalloying, short-process processing technology, intermediate annealing and recrystallization annealing processes. The second phase in the alloy is distributed in a band along the rolling direction, and the Vickers hardness is ≥70HV, the tensile strength is ≥320MPa, the yield strength is ≥190MPa, the elongation is ≥23%, and the cupping value is ≥7mm. It meets the comprehensive requirements of high strength, high toughness and high formability of aluminum alloy sheets for components such as door panels and body panels of new energy vehicles, and has broad application prospects in the preparation of lightweight materials such as inner panels of new energy vehicle bodies. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The second phase distribution diagram of the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy plate prepared in Example 1 of the present invention;

[0023] Figure 2 This is the grain distribution diagram of the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy plate prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The test methods used in the following embodiments are conventional methods unless otherwise specified. The "room temperature" in the present invention, that is, the conventionally understood indoor temperature, is generally 10 to 40°C.

[0025] Example 1

[0026] This embodiment provides a 5XCT3 aluminum alloy plate with high strength, high toughness and high formability, wherein the mass percentages of the alloy raw material components are: V: 0.20%, Ni: 0.15%, Mg: 4.4%, Mn: 0.30%, Si: 0.05%, Fe: 0.05%, Cr: 0.1%, Ti: 0.10%, and the remainder is Al and unavoidable impurities.

[0027] The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet comprises the following steps:

[0028] (1) Melting and casting: The smelting process is to place Al, Mg ingots and various master alloys containing trace elements (V, Ni, Mn, Si, Fe, Cr, Ti) in a pit melting furnace according to the above raw material ratio, and set the melting furnace temperature to 780°C. After the alloy is completely melted, the alloy solution is stirred, the slag is removed, and the furnace temperature is set to 720°C, and then cast into a plate-shaped aluminum alloy ingot with a thickness of 10 mm;

[0029] (2) hot rolling: the plate-shaped aluminum alloy ingot obtained in the above step is air-cooled to 400-450°C, and then hot-rolled in two passes using the residual temperature, with the starting rolling temperature at 440°C and the final rolling temperature at 280°C. After hot rolling, the ingot is air-cooled to room temperature; wherein the pressing amount in each hot rolling pass is 20%-30%;

[0030] (3) cold rolling: the aluminum alloy sheet after hot rolling and cooling in step (2) is subjected to multiple cold rolling processes, with the pressing amount of each cold rolling process being 20% ​​to 25%, and the cold rolling is stopped until the aluminum alloy sheet is thinned to 2.5 to 3.5 mm;

[0031] (4) Intermediate annealing: The alloy sheet after cold rolling is subjected to intermediate annealing treatment; the intermediate annealing temperature is 420°C, kept at this temperature for 4 hours, and then air-cooled to room temperature;

[0032] (5) Finish rolling: The aluminum alloy sheet obtained after the above step is subjected to finish rolling at room temperature to reduce the thickness of the sheet to 1.20 mm;

[0033] (6) Recrystallization annealing: The alloy material after the finish rolling is subjected to recrystallization annealing at a temperature of 375° C. and a holding time of 2 h. After the recrystallization annealing, the alloy material is air-cooled to obtain the high-strength, high-toughness, and high-formability 5XCT3 aluminum alloy sheet of Example 1.

[0034] The high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet prepared in Example 1 was tested for second phase distribution and grain distribution. Figure 1 As shown, the grain distribution diagram is as follows Figure 2 shown.

[0035] Depend on Figure 1 and Figure 2 It can be seen that in the aluminum alloy sheet prepared by the present invention, the second phase is significantly increased, and the size is small, and it is distributed in a band along the rolling direction. At the same time, the alloy grain size is reduced to a certain extent, and the average grain size (equivalent circle diameter) is 12.4μm.

[0036] Example 2

[0037] This embodiment provides a 5XCT3 aluminum alloy plate with high strength, high toughness and high formability, wherein the mass percentages of the alloy raw material components are: V: 0.10%, Ni: 0.20%, Mg: 4.4%, Mn: 0.30%, Si: 0.05%, Fe: 0.05%, Cr: 0.10%, Ti: 0.10%, and the remainder is Al and unavoidable impurities.

[0038] The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet of this embodiment is the same as that of Example 1 except that the alloy raw materials are different from those of Example 1. The second phase distribution and grain distribution test of the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet prepared in Example 2 were conducted. The results showed that the second phase of the aluminum alloy sheet increased significantly, was small in size, and was distributed in a band along the rolling direction. The alloy grain size was reduced to a certain extent, and the average grain size (equivalent circle diameter) was 13.7μm.

[0039] Example 3

[0040] This embodiment provides a 5XCT3 aluminum alloy plate with high strength, high toughness and high formability, and the mass percentages of the alloy raw material components are: V: 0.30%, Ni: 0.10%, Mg: 4.4%, Mn: 0.30%, Si: 0.05%, Fe: 0.05%, Cr: 0.10%, Ti: 0.10%, and the balance is Al and unavoidable impurities.

[0041] The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet of this embodiment is the same as that of Example 1 except that the alloy raw materials are different from those of Example 1. The second phase distribution and grain distribution test of the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet prepared in Example 3 were conducted. The results showed that the second phase of the aluminum alloy sheet increased significantly, was small in size, and was distributed in a band along the rolling direction. The alloy grain size was reduced to a certain extent, and the average grain size (equivalent circle diameter) was 14.4μm.

[0042] Example 4

[0043] This embodiment provides a 5XCT3 aluminum alloy plate with high strength, high toughness and high formability, wherein the mass percentages of the alloy raw material components are: V: 0.15%, Ni: 0.30%, Mg: 4.4%, Mn: 0.30%, Si: 0.05%, Fe: 0.05%, Cr: 0.10%, Ti: 0.10%, and the balance is Al and unavoidable impurities.

[0044] The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy plate of this embodiment is the same as that of Example 1 except that the alloy raw materials are different from those of Example 1, while other processes and parameters are the same as those of Example 1.

[0045] Example 5

[0046] This embodiment provides a 5XCT3 aluminum alloy plate with high strength, high toughness and high formability, wherein the mass percentages of the alloy raw material components are: V: 0.25%, Ni: 0.15%, Mg: 4.4%, Mn: 0.30%, Si: 0.05%, Fe: 0.05%, Cr: 0.10%, Ti: 0.10%, and the balance is Al and unavoidable impurities.

[0047] The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy plate of this embodiment is the same as that of Example 1 except that the alloy raw materials are different from those of Example 1, while other processes and parameters are the same as those of Example 1.

[0048] Example 6

[0049] This embodiment provides a 5XCT3 aluminum alloy plate with high strength, high toughness and high formability, wherein the mass percentages of the alloy raw material components are: V: 0.45%, Ni: 0.20%, Mg: 4.4%, Mn: 0.30%, Si: 0.05%, Fe: 0.05%, Cr: 0.10%, Ti: 0.10%, and the remainder is Al and unavoidable impurities.

[0050] The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy plate of this embodiment is the same as that of Example 1 except that the alloy raw materials are different from those of Example 1, while other processes and parameters are the same as those of Example 1.

[0051] Comparative Example 1

[0052] The comparative example provides a 5XCT3 aluminum alloy plate, the alloy raw material composition does not contain V and Ni elements, and the specific mass percentages are: Mg: 4.4%, Mn: 0.30%, Si: 0.05%, Fe: 0.05%, Cr: 0.10%, Ti: 0.10%, and the balance is Al and unavoidable impurities. The preparation method of the 5XCT3 aluminum alloy plate of the comparative example, except that the alloy raw material is different from that of Example 1, other processes and parameters are the same as those of Example 1. The 5XCT3 aluminum alloy plate prepared in Comparative Example 1 was tested for grain distribution, and the results showed that the average size of the alloy grains (equivalent circle diameter) of the aluminum alloy plate was 17.2μm.

[0053] Comparative Example 2

[0054] The comparative example provides a 5XCT3 aluminum alloy plate, whose alloy raw material composition is the same as that of Example 1. The preparation method of the 5XCT3 aluminum alloy plate of the comparative example is basically the same as that of Example 1, and the difference between the two is that in step (6), the recrystallization annealing temperature is adjusted to 175° C., the holding time is 1 hour, and the rest of the processing technology is consistent with that of Example 1.

[0055] Comparative Example 3

[0056] The comparative example provides a 5XCT3 aluminum alloy plate, and its alloy raw material composition is the same as that of Example 1. The preparation method of the 5XCT3 aluminum alloy plate of the comparative example is basically the same as that of Example 1, and the difference between the two is that: step (1) is the same as that of Example 1; step (2) is: after the plate-shaped aluminum alloy ingot obtained in the above step is air-cooled to room temperature, the plate-shaped aluminum alloy ingot is directly cold-rolled, and the pressing amount of each cold rolling is 20% to 25%, and the cold rolling is stopped until the aluminum alloy plate is thinned to 2.5 to 3.5 mm; steps (3) to (5) are sequentially the same as steps (4) to (6) of Example 1.

[0057] Comparative Example 4

[0058] The comparative example provides a 5XCT3 aluminum alloy plate, whose alloy raw material composition is the same as that of Example 1. The preparation method of the 5XCT3 aluminum alloy plate of the comparative example is basically the same as that of Example 1, and the difference between the two is that the recrystallization annealing process in step (6) is eliminated, and the rest of the processing technology is consistent with that of Example 1.

[0059] Comparative Example 5

[0060] The comparative example provides a 5XCT3 aluminum alloy plate, the mass percentage of the alloy raw material components of which are: V: 0.65%, Mg: 4.4%, Mn: 0.30%, Si: 0.05%, Fe: 0.05%, Cr: 0.10%, Ti: 0.10%, and the balance is Al and unavoidable impurities. The preparation method of the 5XCT3 aluminum alloy plate of the comparative example, except that the alloy raw material is different from that of Example 1, other processes and parameters are the same as those of Example 1. The 5XCT3 aluminum alloy plate prepared in Comparative Example 5 was tested for grain distribution, and the results showed that the average size of the alloy grains (equivalent circle diameter) of the aluminum alloy plate was 18.2μm.

[0061] Comparative Example 6

[0062] The comparative example provides a 5XCT3 aluminum alloy plate, whose alloy raw material composition is the same as that of Example 1. The preparation method of the 5XCT3 aluminum alloy plate of the comparative example is basically the same as that of Example 1, and the difference between the two is that the intermediate annealing process of step (4) is eliminated, and the rest of the processing technology is consistent with that of Example 1.

[0063] Comparative Example 7

[0064] The comparative example provides a 5XCT3 aluminum alloy plate, the mass percentage of the alloy raw material components of which are: Ni: 0.50%, Mg: 4.4%, Mn: 0.30%, Si: 0.05%, Fe: 0.05%, Cr: 0.10%, Ti: 0.10%, and the balance is Al and unavoidable impurities. The preparation method of the 5XCT3 aluminum alloy plate of the comparative example, except that the alloy raw material is different from that of Example 1, other processes and parameters are the same as those of Example 1. The 5XCT3 aluminum alloy plate prepared in Comparative Example 7 was tested for grain distribution, and the results showed that the average size of the alloy grains (equivalent circle diameter) of the aluminum alloy plate was 19.7μm.

[0065] Test example

[0066] The 5XCT3 aluminum alloy sheets prepared in Examples 1 to 6 of the present invention and Comparative Examples 1 to 7 were subjected to microhardness tests, with a test force of 100 gf and a holding time of 15 s; further, the specimens were designed and subjected to tensile performance tests in accordance with GB / T228-2021 "Room Temperature Tensile Test Method for Metallic Materials"; and the specimens were designed and subjected to bulging performance tests of the alloy sheets in accordance with GB / T 4156-2020 "Erichsen Cupping Test for Metallic Materials Sheets and Strips". The properties of the 5XCT3 aluminum alloy sheets of Examples 1 to 6 of the present invention and Comparative Examples 1 to 7 are shown in Table 1.

[0067] Table 1 Performance test results of 5XCT3 aluminum alloy plates obtained in Examples 1 to 6 and Comparative Examples 1 to 7

[0068]

[0069] As can be seen from Table 1, the 5XCT3 aluminum alloy sheets prepared in Examples 1 to 6 of the present invention have a Vickers hardness of 70.9 to 80.0 HV, a tensile strength of 323.2 to 380.3 MPa, a yield strength of 194.6 to 223.3 MPa, an elongation of 23.5% to 27.8%, and a cupping value of 7.3 to 8.2 mm. They have excellent strength, toughness and formability, which greatly meets the comprehensive technical requirements of high strength, toughness and high formability of aluminum alloy sheets for components such as door panels and body panels in new energy vehicles.

[0070] Among them, the comparative example 1 omitted V and Ni elements, and its tensile strength and Vickers hardness were significantly reduced. Since V and Ni elements have a certain effect of inhibiting the recrystallization of the alloy, the Al precipitated during the recrystallization process 10 V and Al3Ni phases will inhibit the growth of recrystallized grains, thereby refining the grains and improving the strength and hardness of the material. However, in Comparative Example 1, V and Ni elements are omitted, resulting in deterioration of the strength and hardness of the material.

[0071] The Vickers hardness of the aluminum alloy plate of Comparative Example 2 is 99.3HV, the tensile strength is 403.6MPa, the yield strength is 292.2MPa, and the elongation is 6.8%, which cannot meet the formability requirements of new energy vehicles for aluminum plates. The reason is that the annealing temperature after final rolling is low, resulting in the failure of the plate to fully recover and recrystallize, more deformed grains, and higher rolling texture, which leads to the brittleness of the material.

[0072] The aluminum alloy sheet prepared in Comparative Example 3 cracked during the cold rolling process, which does not meet the performance requirements of aluminum sheets for new energy vehicles. The reason is that when the deformation amount is large during the cold rolling process, the emergency concentration is increased, the non-uniformity of the deformation is increased, and thus the cracking occurs.

[0073] The aluminum alloy sheet prepared in Comparative Example 4 has a Vickers hardness of 106.1 HV, a tensile strength of 423.3 MPa, a yield strength of 327.5 MPa, an elongation of 4.1%, and a cupping value of 3.1 mm, which cannot meet the formability requirements of new energy vehicles for aluminum sheets. The reason is that the sheet is not annealed after final rolling, resulting in the failure of recovery recrystallization, a highly fibrous structure, and a high rolling texture, which leads to the brittleness of the material.

[0074] The aluminum alloy sheet prepared in Comparative Example 5 has a Vickers hardness of 70.1HV, a tensile strength of 329.6MPa, a yield strength of 198.3MPa, an elongation of 20.3%, and a cupping value of 4.8mm. Compared with Example 1, the forming performance of Comparative Example 5 is greatly reduced. Comparative Example 5 has a high content of V, which leads to the formation of a brittle hard phase Al in the alloy. 10 The V phase segregates, resulting in interface debonding, which has an adverse effect on the forming performance.

[0075] The aluminum alloy sheet prepared in Comparative Example 6 has a Vickers hardness of 76.2 HV, a tensile strength of 363.8 MPa, a yield strength of 200.1 MPa, an elongation of 19.9%, and a cupping value of 6.8 mm. Compared with Example 1, the toughness and formability of Comparative Example 6 are greatly reduced, and cannot meet the toughness and formability requirements of new energy vehicles for aluminum sheets.

[0076] The aluminum alloy sheet prepared in Comparative Example 7 has a Vickers hardness of 72.3 HV, a tensile strength of 330.6 MPa, a yield strength of 199.7 MPa, an elongation of 18.6%, and a cupping value of 5.0 mm. Compared with Example 1, the formability of Comparative Example 7 is greatly reduced. Due to the high content of Ni in Comparative Example 7, a clustering phenomenon of needle-shaped Al3Ni phase is generated in the alloy, which has a relatively adverse effect on the formability.

[0077] Based on the above results, it can be seen that the present invention reduces energy consumption and saves energy and reduces emissions by optimizing the rolling annealing process, especially improving the toughness and formability of aluminum alloy plates. In addition, the present invention has a certain inhibitory effect on the alloy grain size by adding a certain amount of V and Ni elements. Among them, adding V and Ni elements at the same time can make the alloy grain structure finer and increase the number of strengthening phases, thereby effectively improving the alloy strength and formability. Compared with the existing traditional 5XCT3 aluminum alloy, the tensile strength of the 5XCT3 aluminum alloy prepared by the present invention is increased by 20%. In the stamping experiment, the cupping value can reach more than 7mm. Compared with the conventional 5XCT3 aluminum alloy, the formability is better.

[0078] In summary, the present invention can prepare an aluminum alloy sheet with a thickness of 1 to 1.5 mm by combining microalloying, short-process processing technology, intermediate annealing and recrystallization annealing technology. The second phase in the alloy is distributed in a band along the rolling direction, and the Vickers hardness is ≥70HV, the tensile strength is ≥320MPa, the yield strength is ≥190MPa, the elongation is ≥23%, and the cupping value is ≥7mm. It meets the comprehensive requirements of high strength, high toughness and high formability of aluminum alloy sheets for components such as door panels and body panels of new energy vehicles, and has broad application prospects in the preparation of lightweight materials such as inner panels of new energy vehicle bodies.

[0079] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a 5XCT3 aluminum alloy sheet with high strength, high toughness and high formability, characterized in that: The following steps are involved: (1) selecting raw materials according to the composition of the 5XCT3 aluminum alloy plate, mixing the raw materials, smelting them, and then pouring them to obtain a plate-shaped aluminum alloy ingot; (2) cooling the plate-shaped aluminum alloy ingot obtained in step (1) to 400-450° C., performing two hot rolling processes using the residual heat, then cooling to room temperature, and then performing cold rolling to obtain a cold-rolled aluminum alloy plate; (3) performing intermediate annealing on the cold-rolled aluminum alloy sheet, cooling it to room temperature, and then sequentially performing finish rolling and recrystallization annealing to obtain the 5XCT3 aluminum alloy sheet with high strength, high toughness and high formability; The composition of the 5XCT3 aluminum alloy plate is: V 0.10%-0.45%, Ni 0.10%-0.30%, Mg 4.2%-4.6%, Mn 0.25%-0.35%, Si 0.02%-0.10%, Fe 0.02%-0.10%, Cr 0.08%-0.35%, Ti 0.05%-0.15%, and the balance is Al and unavoidable impurities; the temperature of the recrystallization annealing treatment is 350-400° C., and the time is 1-3 h.

2. The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet according to claim 1, characterized in that: In step (1), the smelting temperature is 700-800°C.

3. The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet according to claim 1, characterized in that: In step (1), the thickness of the plate-shaped aluminum alloy ingot is 8 to 12 mm.

4. The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet according to claim 1, characterized in that: In step (2), the pressing amount of each hot rolling process is 20% to 35%.

5. The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet according to claim 1, characterized in that: In step (2), the pressing amount of each cold rolling process is 20% to 25%.

6. The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet according to claim 1, characterized in that: In step (2), the thickness of the aluminum alloy sheet is reduced to 2.5 to 3.5 mm after cold rolling.

7. The method for preparing the high-strength, high-toughness and high-formability 5XCT3 aluminum alloy sheet according to any one of claims 1 to 6, characterized in that: In step (3), the temperature of the intermediate annealing treatment is 400-450° C., and the holding time is 3-5 hours.

8. The method for preparing the 5XCT3 aluminum alloy sheet with high strength, high toughness and high formability according to any one of claims 1 to 6, characterized in that: In step (3), the cooling is air cooling.

9. The method for preparing a 5XCT3 aluminum alloy sheet with high strength, high toughness and high formability according to any one of claims 1 to 6, characterized in that: In step (3), the finish rolling treatment is to reduce the thickness of the aluminum alloy plate to 1.0 to 1.5 mm.

10. A 5XCT3 aluminum alloy sheet with high strength, high toughness and high formability prepared by the preparation method according to any one of claims 1 to 9.

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