Preparation method and application of Al-Mg-Mn-Sc series aluminum alloy plate

Abstract

The invention provides a preparation method of an Al-Mg-Mn-Sc series aluminum alloy plate. The preparation method comprises the following steps: S1, carrying out hot rolling on an Al-Mg-Mn-Sc series aluminum alloy cast ingot; s2, the hot-rolled aluminum alloy plate is pre-annealed and then cold-rolled for the first time; s3, carrying out intermediate annealing on the cold-rolled aluminum alloy plate, and then carrying out secondary cold rolling; and S4, the aluminum alloy plate obtained in the step S3 is subjected to air cushion furnace rapid annealing. The invention further provides application of the aluminum alloy plate prepared through the method. According to the preparation method of the Al-Mg-Mn-Sc series aluminum alloy plate, through accurate component regulation and control and process optimization, the strength of the aluminum alloy plate is improved, and the mechanical property of the aluminum alloy plate is not obviously reduced under the 280 DEG C brazing machining condition.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a preparation method and application of an Al-Mg-Mn-Sc series aluminum alloy plate. Background Art

[0002] 5xxx aluminum alloy is one of the most widely used rust-proof aluminum alloys in industry. It is known for its excellent corrosion resistance, medium strength, and good processing properties. Currently, 5xxx aluminum alloy products use a box-type Steckel heat treatment process during cold rolling pre-annealing and intermediate annealing. The annealing temperature is generally between 350 and 410°C. After annealing, it has the following characteristics:

[0003] 1) The annealing temperature is too high. During annealing, the material undergoes complete recovery and recrystallization, and the material becomes soft. After the material softens, it is cold-rolled again. The strength of the material increases relatively slowly. Even after more than 40% cold deformation, the material still cannot meet its high strength requirements.

[0004] 2) The material has extremely high strength after cold rolling and hardening, and the yield strength in the H18 state can reach more than 480MPa. After the material strength is increased, it is relatively difficult to continue cold rolling. The main problems are small rolling reduction, difficulty in controlling the rolled plate shape, and brittle fracture during cold rolling coiling.

[0005] With the demand for aluminum alloy performance in modern industry, the applicant has developed a new Al-Mg-Mn-Sc aluminum alloy through continuous research and experimental exploration. The preparation method of 5xxx aluminum alloy in the existing technology cannot meet the performance requirements of high temperature resistance and strength. Summary of the Invention

[0006] The technical problem solved by the present invention is to provide a method for preparing an Al-Mg-Mn-Sc series aluminum alloy plate. The aluminum alloy plate prepared by the preparation method provided in this application has excellent mechanical properties and performance stability.

[0007] In view of this, the present application provides a method for preparing an Al-Mg-Mn-Sc series aluminum alloy plate, comprising the following steps:

[0008] S1, hot rolling an Al-Mg-Mn-Sc aluminum alloy ingot;

[0009] S2. Pre-annealing the hot-rolled aluminum alloy sheet and then performing a first cold rolling; the pre-annealing temperature is ≤320° C.;

[0010] S3, performing intermediate annealing on the aluminum alloy sheet obtained in step S2, and then performing a second cold rolling; the intermediate annealing temperature is ≤320°C;

[0011] S4, performing rapid annealing of the aluminum alloy plate obtained in step S3 in an air cushion furnace; the temperature of the rapid annealing in the air cushion furnace is ≥300° C.;

[0012] Calculated by mass percentage, the Al-Mg-Mn-Sc aluminum alloy plate includes: Mn 0.5-0.8%, Mg 3.8-4.4%, Cr 0.05-0.50%, Zn 0.01-0.50%, Ti 0.01-0.35%, Sc 0.01-0.50%, Si≤0.40%, Fe≤0.40%, Al balance and unavoidable impurities.

[0013] In some specific embodiments, in step S1 , the hot rolling temperature is 400-500° C., and the hot rolling deformation rate is 98.0%-99.5%.

[0014] In some specific embodiments, in step S2, the pre-annealing temperature is 150-320° C., and the holding time is 1-8 hours.

[0015] In some specific embodiments, the total deformation rate of the first cold rolling and the second cold rolling is 75% to 85%.

[0016] In some specific embodiments, the deformation rate of the first cold rolling is 40% to 60%, and the total deformation rate of the second cold rolling is 40% to 60%.

[0017] In some specific embodiments, the intermediate annealing temperature is 150-320° C., and the holding time is 1-8 hours.

[0018] In some specific embodiments, the air cushion furnace rapid annealing adopts single coil unfolding heat treatment, the air cushion furnace temperature of the air cushion furnace rapid annealing is 360-450°C, the process speed is 12-15m / min, the air cushion pressure is 30-70mmHg, and the time is 3-10min.

[0019] In some specific embodiments, the Al-Mg-Mn-Sc aluminum alloy plate includes: Mn 0.6-0.7%, Mg 3.9-4.2%, Cr 0.12-0.35%, Zn 0.15-0.30%, Ti 0.12-0.30%, Sc 0.12-0.32%, Si≤0.40%, Fe≤0.40%, Al balance and unavoidable impurities.

[0020] In some specific embodiments, the air cushion furnace rapid annealing further includes stretching and straightening, and the tensile stress of the stretching and straightening is 1% to 2%.

[0021] The present application also provides the use of the aluminum alloy plate prepared by the preparation method in the preparation of wind power blades.

[0022] The present application provides a method for preparing an Al-Mg-Mn-Sc series aluminum alloy plate, which firstly hot-rolls an Al-Mg-Mn-Sc series aluminum alloy ingot, then sequentially performs pre-annealing, first cold rolling, intermediate annealing and second cold rolling on the obtained aluminum alloy plate, and finally performs rapid annealing in an air cushion furnace on the obtained aluminum alloy plate; in the preparation process of the Al-Mg-Mn-Sc series aluminum alloy plate, the introduction and content control of alloying elements such as Sc and Zr significantly improve the mechanical properties and high temperature resistance of the aluminum alloy; at the same time, the pre-annealing and intermediate annealing are respectively introduced before the first cold rolling and before the second cold rolling, and the temperature is limited. The temperature is controlled so that the aluminum alloy plate does not undergo complete recovery and recrystallization, and only the stress generated during the cold rolling process is effectively eliminated, and the grain size does not change significantly. Therefore, when the second cold rolling is performed, the strength of the aluminum alloy plate can be rapidly improved; and, after the aluminum alloy plate of the present application undergoes a series of process treatments of hot rolling-pre-annealing-first cold rolling-intermediate annealing-second cold rolling-air cushion furnace rapid annealing, when kept warm at 280°C for 10 minutes in a specific application, its yield strength can still be stably maintained at above 280MPa, and its tensile strength can be maintained at above 350MPa, that is, the aluminum alloy plate shows excellent performance stability and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the rapid annealing process in an air cushion furnace during the preparation of an Al-Mg-Mn-Sc series aluminum alloy plate according to the present invention; in the figure, 1 is the aluminum alloy plate, 2 is the nozzle, 3 is the floating waviness of the aluminum alloy plate, and 4 is the floating height of the aluminum alloy plate;

[0024] Figure 2 This is a schematic diagram of the stretching, bending and straightening process during the preparation of the Al-Mg-Mn-Sc aluminum alloy plate of the present invention; in the figure, 1 is a straightening roller and 2 is a tension roller. DETAILED DESCRIPTION

[0025] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0026] In view of the requirements for mechanical properties and performance stability of 5xxx aluminum alloys in the prior art, the present application provides a method for preparing Al-Mg-Mn-Sc series aluminum alloy plates, which includes hot rolling-pre-annealing-first cold rolling-intermediate annealing-second cold rolling-air cushion furnace rapid annealing in sequence. By introducing low-temperature pre-annealing and low-temperature intermediate annealing before cold rolling, the grain structure does not undergo recovery and recrystallization, thereby ensuring the high strength and high-temperature resistance of the aluminum alloy plates. The introduction of alloying elements such as Sc and Zr significantly improves the key properties of the aluminum alloy plates, such as mechanical properties and high-temperature resistance. Furthermore, the present application adopts a heat treatment method of suspended rapid annealing in an air cushion furnace, and improves the plate shape by stretching, bending and straightening, which is beneficial to improving the flatness of the aluminum alloy plates and provides a plate shape guarantee for the subsequent brazing of aluminum alloy materials. Specifically, the present application provides a method for preparing Al-Mg-Mn-Sc series aluminum alloy plates, which includes the following steps:

[0027] S1, hot rolling an Al-Mg-Mn-Sc aluminum alloy ingot;

[0028] S2. Pre-annealing the hot-rolled aluminum alloy sheet and then performing a first cold rolling; the pre-annealing temperature is ≤320° C.;

[0029] S3, performing intermediate annealing on the aluminum alloy sheet obtained in step S2, and then performing a second cold rolling; the intermediate annealing temperature is ≤320°C;

[0030] S4, performing rapid annealing of the aluminum alloy plate obtained in step S3 in an air cushion furnace; the temperature of the rapid annealing in the air cushion furnace is ≥300° C.;

[0031] Calculated by mass percentage, the Al-Mg-Mn-Sc aluminum alloy plate includes: Mn 0.5-0.8%, Mg 3.8-4.4%, Cr 0.05-0.50%, Zn 0.01-0.50%, Ti 0.01-0.35%, Sc 0.01-0.50%, Si≤0.40%, Fe≤0.40%, Al balance and unavoidable impurities.

[0032] In the preparation process of Al-Mg-Mn-Sc aluminum alloy plate, the Al-Mg-Mn-Sc aluminum alloy ingot is first hot-rolled. The preparation method of the Al-Mg-Mn-Sc aluminum alloy ingot is carried out according to the method well known to those skilled in the art, namely, batching-smelting-casting-homogenization treatment. The above steps are carried out according to the method well known to those skilled in the art. After the Al-Mg-Mn-Sc aluminum alloy ingot is obtained, it is hot-rolled. The hot rolling is a process of deforming the heated ingot by rolling to form a plate of the desired thickness. In this application, the hot rolling temperature is 400-500°C, specifically 420-450°C; the hot rolling deformation rate is 98.0%-99.5%, specifically 98.8-99.2%.

[0033] The total deformation rate of the first and second cold rolling processes described in this application is 75% to 85%. This high cold rolling deformation rate transforms the microstructure of the aluminum alloy sheet into a cold-rolled fiberized state, imparting high strength to the aluminum alloy sheet. Since the aluminum alloy exhibits high strength (yield strength up to 480 MPa) when cold-rolled to the H18 state, this significantly increases the difficulty in controlling the cold-rolled and straightened sheet shapes. During the cold rolling process, high-strength materials are often more prone to poor sheet shapes such as edge waves and second rib waves, which poses a production challenge. Therefore, to effectively reduce the difficulty of cold rolling, this application introduces pre-annealing and intermediate annealing before the first and second cold rolling passes, respectively. The intermediate cold rolling pass employs an intermediate annealing followed by another cold rolling pass to reduce cold rolling stress, thereby improving the ability to control the cold rolling sheet shape. The pre-annealing and intermediate annealing processes are independently heat-treated at a temperature of ≤320°C. Under these temperature conditions, the aluminum alloy sheet does not undergo a complete recovery and recrystallization process, but rather effectively eliminates the stress generated during the cold rolling process, without significantly changing the grain size of the aluminum alloy sheet. Since the aluminum alloy sheet does not undergo recovery recrystallization, the strength of the aluminum alloy sheet can be rapidly improved during the second cold rolling, thereby achieving higher performance. Specifically, the pre-annealing temperature is 150-320°C, and the holding time is 1-8 hours. More specifically, the pre-annealing temperature is 180-280°C, and the holding time is 2-6 hours. More specifically, the pre-annealing temperature is 220-250°C, and the holding time is 3-5 hours. The deformation rate of the first cold rolling is 40%-60%, and the number of passes is 3. Specifically, the deformation rate of the first cold rolling is 43%-56%. More specifically, the deformation rate of the first cold rolling is 45%-53%. Specifically, the intermediate annealing temperature is 150-320°C, and the holding time is 1-8 hours. More specifically, the intermediate annealing temperature is 180-280°C, and the holding time is 2-6 hours. More specifically, the intermediate annealing temperature is 200-250°C, and the holding time is 4.5-5 hours. The deformation rate of the second cold rolling is 40%-60%, and the number of passes is 3. Specifically, the deformation rate of the second cold rolling is 42-56%, and more specifically, the deformation rate of the second cold rolling is 45%-52%. If the above-mentioned pre-annealing or intermediate annealing is missing or the temperature is not within the above range, the strength of the aluminum alloy sheet will be too high, the edges will easily crack, and it will be impossible to cold-roll the finished product.

[0034] After the second cold rolling, the aluminum alloy sheet needs to be annealed. Its properties are shown in Table 1:

[0035] Table 1 Performance data of aluminum alloy sheets after the second cold rolling and annealing

[0036]

[0037] From the above data in Table 1, it can be seen that the strength of the aluminum alloy sheet after annealing is still relatively high, and the plate shape control is relatively difficult when the strip is subsequently handed over to the customer for straightening and shearing. In order to effectively improve the straightness of the aluminum alloy sheet, after in-depth research and repeated experiments, this application adopts air cushion furnace rapid annealing, and the annealing temperature is ≥300℃. Annealing at this temperature is beneficial to the aluminum alloy sheet to maintain its performance during the subsequent brazing at 280℃ for 10 minutes. At the same time, the process of rapid annealing in the air cushion furnace is strictly controlled to ensure that all performance indicators of the aluminum alloy sheet meet the standard requirements after annealing.

[0038] Air cushion furnace rapid annealing is a highly efficient heat treatment process for metal strips, which combines air cushion suspension technology and rapid heating / cooling technology to improve the performance of metal strips. The air cushion furnace rapid annealing is carried out in an air cushion continuous heat treatment furnace, using a single coil unwinding heat treatment method, and can be used for continuous annealing and quenching heat treatment of strips. Since the residence time of all parts of the entire coil of aluminum alloy sheet in the furnace is exactly the same when passing through the air cushion furnace, the heating rate, holding time, and cooling rate of sheets of the same thickness are exactly the same, and the performance after heat treatment is relatively stable. The annealing principle is as follows: Figure 1 In the present application, the air cushion furnace temperature for rapid annealing in the air cushion furnace is 360-450°C, the process speed is 12-15 m / min, the air cushion pressure is 30-70 mmHg, and the time is 3-10 min; specifically, the air cushion furnace temperature for rapid annealing in the air cushion furnace is 380-425°C, the process speed is 13-14 m / min, the air cushion pressure is 40-65 mmHg, and the time is 4-9 min; more specifically, the air cushion furnace temperature for rapid annealing in the air cushion furnace is 390-410°C, the air cushion pressure is 45-58 mmHg, and the time is 5-8 min; more specifically, the air cushion furnace temperature for rapid annealing in the air cushion furnace is 395-405°C, the air cushion pressure is 50-53 mmHg, and the time is 6-7 min.

[0039] After the aluminum alloy plate has been rapidly annealed in the air cushion furnace, it also includes stretch and bend straightening to further improve the plate shape. Stretch and bend straightening is an effective plate shape adjustment method that can make the material plate shape straighter by applying appropriate tension and bending force. The stretch and bend straightening principle is shown in Figure 2 . In the present application, the tensile stress of the stretch-bend straightening is 1.0% to 2.0%. Specifically, the tensile stress of the stretch-bend straightening is 1.2% to 1.7%. In a specific embodiment, the tensile stress of the stretch-bend straightening is 1.5%. This processing method creates extremely favorable conditions for controlling the plate shape during subsequent straightening and shearing processing, reduces the processing difficulty and quality risks caused by plate shape problems, thereby not only improving the applicability of the material, but also enhancing the competitiveness of the material in the market, laying a solid foundation for the wide application of the material in various fields.

[0040] In this application, the Al-Mg-Mn-Sc aluminum alloy sheet comprises, by mass percentage, the following: Mn 0.5-0.8%, Mg 3.8-4.4%, Cr 0.05-0.50%, Zn 0.01-0.50%, Ti 0.01-0.35%, Sc 0.01-0.50%, Si ≤ 0.40%, Fe ≤ 0.40%, the remainder being Al and unavoidable impurities. By adding alloying elements such as Sc and Zr and adjusting their content, the aluminum alloy sheet significantly improves key properties such as mechanical properties and high-temperature resistance. This new aluminum alloy exhibits high specific strength and hardness, enabling it to withstand greater loads in practical applications while ensuring structural stability and reliability. Specifically, the Mn content is 0.6-0.7%. Specifically, the Mg content is 3.9-4.2%, and more specifically, the Mg content is 4.0-4.1%. Specifically, the Cr content is 0.08-0.46%, more specifically, the Cr content is 0.10-0.42%, more specifically, the Cr content is 0.12-0.35%, more specifically, the Cr content is 0.18-0.32%, more specifically, the Cr content is 0.20-0.28%, more specifically, the Cr content is 0.23-0.26%. Specifically, the Zn content is 0.08-0.42%, more specifically, the Zn content is 0.10-0.37%, more specifically, the Zn content is 0.15-0.35%, more specifically, the Zn content is 0.18-0.27%, more specifically, the Zn content is 0.21-0.25%. Specifically, the Ti content is 0.06-0.32%, more specifically, the Ti content is 0.12-0.30%, more specifically, the Ti content is 0.15-0.27%, more specifically, the Ti content is 0.18-0.25%, more specifically, the Ti content is 0.20-0.22%. Specifically, the Sc content is 0.06-0.42%, more specifically, the Sc content is 0.10-0.40%, more specifically, the Sc content is 0.12-0.38%, more specifically, the Sc content is 0.15-0.28%, more specifically, the Sc content is 0.18-0.26%, more specifically, the Sc content is 0.21-0.24%.

[0041] The present application also provides the use of the aluminum alloy plate prepared by the above preparation method in the preparation of wind power blades.

[0042] The aluminum alloy plate prepared in the present application is used in the preparation process of wind turbine blades, and can be brazed at 280° C. for 10 minutes without a significant decrease in mechanical properties.

[0043] The present application provides a method for preparing an Al-Mg-Mn-Sc series aluminum alloy plate. First of all, from the perspective of material composition, the Al-Mg-Mn-Sc series aluminum alloy plate is an innovative improvement on the traditional 5xxx high-magnesium aluminum alloy; by adding alloying elements such as Sc and Zr and controlling their content, the key properties of the aluminum alloy, such as mechanical properties and high-temperature resistance, are significantly improved; this new aluminum alloy exhibits high specific strength and hardness, and can withstand greater loads in practical applications while ensuring structural stability and reliability.

[0044] The aluminum alloy sheet prepared in this application performs well in terms of thermal processing properties, can adapt to various complex processing technologies, and provides greater flexibility for production and manufacturing; in addition, its excellent welding performance also makes the component connection and assembly process more convenient and efficient, reducing production costs and process difficulty.

[0045] It is particularly worth mentioning that the aluminum alloy sheet prepared in this application has important application value in the manufacture of wind turbine blades; under the conditions of 280°C brazing processing (holding temperature for 10 minutes), its mechanical properties can maintain the original high performance without significant decline. This feature ensures the stability and reliability of wind turbine blades in harsh working environments, extends the service life of the blades, and improves the overall efficiency of the wind power generation system. Therefore, compared with the existing technology, this new aluminum alloy has achieved a major breakthrough in performance. Traditional aluminum alloys often have the problem of mechanical property degradation in high temperature environments, but the present invention has successfully overcome this problem through precise composition control and process optimization. It provides a more reliable and efficient material solution for fields such as wind power generation. Experimental results show that the aluminum alloy sheet prepared in this application has a yield strength of ≥280MPa, a tensile strength of ≥350MPa, and an elongation of ≥12%, and the sheet can be held at 280°C for 10 minutes without a significant decrease in strength.

[0046] In order to further understand the present invention, the preparation method of the Al-Mg-Mn-Sc series aluminum alloy plate provided by the present invention is described in detail below with reference to the examples. The protection scope of the present invention is not limited by the following examples.

[0047] Example 1

[0048] Step 1: heating an aluminum alloy ingot with a thickness of 460 mm and the composition shown in Table 2 to 450° C. and rolling it to 5.5 mm at a deformation rate of 98.8%;

[0049] Step 2: pre-annealing the aluminum alloy sheet obtained in step 1, and then rolling it to 2.6 mm at a deformation rate of 52.7%, wherein the pre-annealing temperature is 220° C. and the temperature is kept for 4.5 hours;

[0050] Step 3: The aluminum alloy sheet obtained in step 2 is subjected to intermediate annealing, and then rolled to 1.5 mm at a deformation rate of 42.3%, wherein the intermediate annealing temperature is 200° C. and the temperature is kept for 5 hours;

[0051] Step 4: The aluminum alloy plate obtained in step 3 is subjected to rapid annealing in an air cushion furnace, wherein the air cushion furnace temperature is 410° C., the process speed is 14 m / min, the air cushion pressure is 53 mmHg, and the time is 6 min;

[0052] Step 5: The aluminum alloy sheet obtained in step 4 is subjected to stretching, bending and straightening to obtain an aluminum alloy sheet.

[0053] The properties of the aluminum alloy plate prepared in this embodiment were tested, and the test results are shown in Table 3.

[0054] Example 2

[0055] Step 1: heating an aluminum alloy ingot with a thickness of 460 mm and the composition shown in Table 2 to 450° C. and rolling it to 5.5 mm at a deformation rate of 98.8%;

[0056] Step 2: pre-annealing the aluminum alloy sheet obtained in step 1, and then rolling it to 2.6 mm at a deformation rate of 52.7%, wherein the pre-annealing temperature is 220° C. and the temperature is kept for 4.5 hours;

[0057] Step 3: The aluminum alloy sheet obtained in step 2 is subjected to intermediate annealing, and then rolled to 1.5 mm at a deformation rate of 42.3%, wherein the intermediate annealing temperature is 200° C. and the temperature is kept for 5 hours;

[0058] Step 4: The aluminum alloy plate obtained in step 3 is subjected to rapid annealing in an air cushion furnace, wherein the air cushion furnace temperature is 410° C., the process speed is 14 m / min, the air cushion pressure is 53 mmHg, and the time is 6 min;

[0059] Step 5: The aluminum alloy sheet obtained in step 4 is subjected to stretching, bending and straightening to obtain an aluminum alloy sheet.

[0060] The properties of the aluminum alloy plate prepared in this embodiment were tested, and the test results are shown in Table 3.

[0061] Example 3

[0062] Step 1: heating an aluminum alloy ingot with a thickness of 460 mm and the composition shown in Table 2 to 450° C. and rolling it to 5.5 mm at a deformation rate of 98.8%;

[0063] Step 2: pre-annealing the aluminum alloy sheet obtained in step 1, and then rolling it to 2.6 mm at a deformation rate of 52.7%, wherein the pre-annealing temperature is 220° C. and the temperature is kept for 4.5 hours;

[0064] Step 3: The aluminum alloy sheet obtained in step 2 is subjected to intermediate annealing, and then rolled to 1.5 mm at a deformation rate of 42.3%, wherein the intermediate annealing temperature is 200° C. and the temperature is kept for 5 hours;

[0065] Step 4: The aluminum alloy plate obtained in step 3 is subjected to rapid annealing in an air cushion furnace, wherein the air cushion furnace temperature is 410° C., the process speed is 14 m / min, the air cushion pressure is 53 mmHg, and the time is 6 min;

[0066] Step 5: The aluminum alloy sheet obtained in step 4 is subjected to stretching, bending and straightening to obtain an aluminum alloy sheet.

[0067] The properties of the aluminum alloy plate prepared in this embodiment were tested, and the test results are shown in Table 3.

[0068] Comparative Example 1

[0069] The preparation method is the same as that of Example 1, except that the pre-annealing temperature is 330°C.

[0070] The properties of the aluminum alloy plate prepared in this embodiment were tested, and the test results are shown in Table 3.

[0071] Comparative Example 2

[0072] The preparation method is the same as that of Example 2, except that the intermediate annealing temperature is 350°C.

[0073] The properties of the aluminum alloy plate prepared in this embodiment were tested, and the test results are shown in Table 3.

[0074] Table 2 Composition data of aluminum alloy plates in the embodiment

[0075]

[0076] Table 3 Performance data of aluminum alloy plates prepared in Example

[0077] Group Thickness (mm) Yield strength MPa Tensile strength MPa Elongation% Example 1 1.0 379-384 430-436 13.5-14.5 Example 2 1.0 374-383 434-442 14.0-15.0 Example 3 1.0 374-378 429-431 14.0-15.5 Comparative Example 1 1.0 250-320 350-400 13.5-15.0 Comparative Example 2 1.0 170-250 310-360 13.0-19.0

[0078] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0079] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an Al-Mg-Mn-Sc aluminum alloy plate, comprising the following steps: S1, hot rolling an Al-Mg-Mn-Sc aluminum alloy ingot; S2. Pre-annealing the hot-rolled aluminum alloy sheet and then performing a first cold rolling; the pre-annealing temperature is ≤320° C.; S3, performing intermediate annealing on the aluminum alloy sheet obtained in step S2, and then performing a second cold rolling; the intermediate annealing temperature is ≤320°C; S4, performing rapid annealing of the aluminum alloy plate obtained in step S3 in an air cushion furnace; The temperature of the air cushion furnace rapid annealing is ≥300°C; Calculated by mass percentage, the Al-Mg-Mn-Sc aluminum alloy plate includes: Mn 0.5-0.8%, Mg 3.8-4.4%, Cr 0.05-0.50%, Zn 0.01-0.50%, Ti 0.01-0.35%, Sc 0.01-0.50%, Si≤0.40%, Fe≤0.40%, Al balance and unavoidable impurities.

2. The preparation method according to claim 1, characterized in that In step S1 , the hot rolling temperature is 400-500° C., and the hot rolling deformation rate is 98.0%-99.5%.

3. The preparation method according to claim 1 or 2, characterized in that In step S2, the pre-annealing temperature is 150-320° C., and the holding time is 1-8 hours.

4. The preparation method according to claim 3, characterized in that The total deformation rate of the first cold rolling and the second cold rolling is 75% to 85%.

5. The preparation method according to claim 4, characterized in that The deformation rate of the first cold rolling is 40% to 60%, and the total deformation rate of the second cold rolling is 40% to 60%.

6. The preparation method according to claim 4, characterized in that The intermediate annealing temperature is 150-320° C., and the holding time is 1-8 hours.

7. The preparation method according to claim 6, characterized in that The air cushion furnace rapid annealing adopts single coil unfolding heat treatment, the air cushion furnace temperature of the air cushion furnace rapid annealing is 360-450°C, the process speed is 12-15m / min, the air cushion pressure is 30-70mmHg, and the time is 3-10min.

8. The preparation method according to any one of claims 1 to 7, characterized in that The Al-Mg-Mn-Sc series aluminum alloy plate comprises: Mn 0.6-0.7%, Mg 3.9-4.2%, Cr 0.12-0.35%, Zn 0.15-0.30%, Ti 0.12-0.30%, Sc 0.12-0.32%, Si≤0.40%, Fe≤0.40%, Al balance and inevitable impurities.

9. The preparation method according to any one of claims 1 to 7, characterized in that The air cushion furnace rapid annealing further includes stretching and bending straightening, wherein the tensile stress of the stretching and bending straightening is 1% to 2%.

10. Use of the aluminum alloy plate prepared by the preparation method according to any one of claims 1 to 9 in the preparation of wind power blades.

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