A rare earth aluminum alloy plate and a method for manufacturing the same

Abstract

The application relates to a rare earth aluminum alloy plate and a preparation method thereof, and has the purposes of solving the problem that the existing aluminum alloy plate is difficult to have high strength and high toughness, and the rare earth aluminum alloy plate comprises the following elements in percentage by mass: the content of Mg element is 4.2-5.0 wt%, the content of Mn element is 0.14-0.20 wt%, the content of Sc element is 0.12-0.20 wt%, the content of Zr element is 0.10-0.13 wt%, the content of Ti element is 0.05-0.15 wt%, the total content of inevitable impurities is less than or equal to 0.15 wt%, the content of single impurity is less than or equal to 0.05 wt%, and the balance is Al element. The addition of the Sc element and the Zr element helps to improve the strength and the toughness of the rare earth aluminum alloy plate. The application is applied to the technical field of aluminum alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to a rare earth aluminum alloy plate and a preparation method thereof. BACKGROUND

[0002] Aluminum alloy has the characteristics of light specific gravity, high specific strength, low cost, easy processing, corrosion resistance and the like, and has been a key structural material indispensable in the global aerospace field for a long time. In the contemporary aerospace manufacturing industry, aluminum alloy has been one of the most important materials for aircraft body structures, and its amount accounts for about 40% to 70% of the weight of the aircraft body structure, and is widely used in aircraft main load-bearing frames, beams, wall plates, skins and the like. With the rapid development of the aviation industry, it is urgent to develop aluminum alloys with better comprehensive properties such as strength and toughness to replace the existing alloys and meet the material requirements for upgrading and updating of new generation of aviation equipment. SUMMARY

[0003] The present application aims to solve the problem that the existing aluminum alloy plate cannot simultaneously have high strength and high toughness, and provides a rare earth aluminum alloy plate and a preparation method thereof.

[0004] The rare earth aluminum alloy plate is composed of 4.2-5.0% of Mg, 0.14-0.20% of Mn, 0.12-0.20% of Sc, 0.10-0.13% of Zr, 0.05-0.15% of Ti and the balance of Al in terms of mass percentage; and the mass ratio of Sc element to Zr element is 1.36-1.55:1.

[0005] The preparation method of the rare earth aluminum alloy plate is carried out according to the following steps:

[0006] I. The raw materials are weighed according to the proportions of 4.2-5.0% of Mg, 0.14-0.20% of Mn, 0.12-0.20% of Sc, 0.10-0.13% of Zr, 0.05-0.15% of Ti and the balance of Al in terms of mass percentage, and then casting is carried out to obtain a rare earth aluminum alloy ingot;

[0007] II. The aluminum alloy ingot is subjected to homogenization heat treatment at 340-360℃ for 16-18h, and then heated to 440-460℃ for 10-14h, and then subjected to hot rough rolling and hot finish rolling to obtain a hot finish rolling coil; wherein the number of passes of the hot rough rolling is 17-19 passes, the sum of the processing rates of each pass is 94-95.5%, and the rolling speed is 1.50-3.00m·s -1 ; the number of passes of the hot finish rolling is 3 passes, the processing rates of each pass are 30-45% respectively, and the rolling speed is 2.00-3.00m·s -1 ; and then the hot finish rolling coil is uncoiled and cut into pieces, and annealing treatment is carried out to obtain a rare earth aluminum alloy plate.

[0008] The addition of Mg element in the rare earth aluminum alloy plate of the present application helps to improve the strength and stiffness of the rare earth aluminum alloy plate, while reducing the density of the rare earth aluminum alloy plate. The addition of Mn element helps to improve the strength, plasticity and corrosion resistance of the rare earth aluminum alloy plate. The addition of Sc element and Zr element helps to form fine and dispersed Al3(Sc, Zr) second phase in the aluminum alloy ingot during homogenization heat treatment, thereby helping to improve the strength and toughness of the rare earth aluminum alloy plate. The addition of Ti element helps to improve the strength, corrosion resistance and heat resistance of the rare earth aluminum alloy plate. It is preferred to control the mass percentage of Mg element, Mn element, Sc element, Zr element and Ti element within the above range, which helps to improve the mutual synergy between the elements, thereby further improving the comprehensive performance of the rare earth aluminum alloy plate, such as strength, corrosion resistance and toughness. The rare earth aluminum alloy plate of the present application has important application value in the structure of the aircraft nose, lip, leading edge, wing, straight section fuselage and the like, and can replace the application parts of 2024, 2524 and other 2xxx series alloys in situ, thereby helping to reduce the weight of the aircraft and prolong the service life of the aircraft. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 It is an optical photograph of the hot finished coil in Example 1 of the present application;

[0010] Figure 2 It is an optical photograph of the rare earth aluminum alloy plate in Example 1 of the present application;

[0011] Figure 3 It is a microstructure diagram of the rare earth aluminum alloy plate in Example 1 of the present application;

[0012] Figure 4 It is a microstructure diagram of the rare earth aluminum alloy plate in Comparative Example 4 of the present application. DETAILED DESCRIPTION

[0013] The technical solution of the present application is not limited to the following specific embodiments, but also includes any combination between the specific embodiments.

[0014] Specific embodiment one: the rare earth aluminum alloy plate of the present embodiment is composed of Mg element with a mass percentage of 4.2-5.0%, Mn element with a mass percentage of 0.14-0.20%, Sc element with a mass percentage of 0.12-0.20%, Zr element with a mass percentage of 0.10-0.13%, Ti element with a mass percentage of 0.05-0.15%, and the balance of Al; and the mass ratio of Sc element to Zr element is 1.36-1.55:1.

[0015] The total content of unavoidable impurities in the rare earth aluminum alloy plate of the present embodiment is ≤0.15wt%, and the content of a single impurity is not more than 0.05wt%.

[0016] The addition of Mg element in the rare earth aluminum alloy sheet helps to improve the strength and stiffness of the rare earth aluminum alloy sheet, while reducing the density of the rare earth aluminum alloy sheet. The addition of Mn element helps to improve the strength, plasticity and corrosion resistance of the rare earth aluminum alloy sheet. The addition of Sc element and Zr element helps to form fine and dispersed Al3(Sc, Zr) second phase in the aluminum alloy ingot during homogenization heat treatment, thereby helping to improve the strength and toughness of the rare earth aluminum alloy sheet. The addition of Ti element helps to improve the strength, corrosion resistance and heat resistance of the rare earth aluminum alloy sheet. Preferably, the mass percentage of Mg element, Mn element, Sc element, Zr element and Ti element is controlled within the above range, which helps to improve the mutual synergy between the elements, thereby further improving the comprehensive performance of the rare earth aluminum alloy sheet, such as strength, corrosion resistance and toughness. The rare earth aluminum alloy sheet of the present embodiment has important application value in the structure of the aircraft nose, lip, leading edge, wing, straight section fuselage, etc. It can replace the application parts of 2024, 2524 and other 2xxx series alloys in situ, thereby helping to reduce the weight of the aircraft and prolong the service life of the aircraft.

[0017] Specific embodiment two: the difference between the present embodiment and specific embodiment one is that the rare earth aluminum alloy sheet is composed of 4.6-4.9% of Mg element, 0.15-0.19% of Mn element, 0.15-0.18% of Sc element, 0.11-0.12% of Zr element, 0.06-0.12% of Ti element and the balance of Al. Other aspects are the same as specific embodiment one.

[0018] Preferably, the mass percentage of Mg element, Mn element, Sc element, Zr element and Ti element is controlled within the above range, which helps to further improve the mutual synergy between the elements, thereby further improving the comprehensive performance of the rare earth aluminum alloy sheet, such as strength, corrosion resistance and toughness. The mass ratio of Sc element to Zr element is too large, which is not conducive to the control of coarse Sc-containing compound primary phase. Once coarse Sc-containing compound primary phase appears in the structure, it will have an adverse effect on the comprehensive performance of the product. The mass ratio of Sc element to Zr element is too small, which is not conducive to the formation and distribution of Al3(Sc, Zr) phase. The increase of Sc element will also increase the cost of raw materials. Preferably, the mass ratio of Sc element to Zr element is controlled within the above range, which helps to fully exert the synergy between Sc element and Zr element, so that more fine and dispersed Al3(Sc, Zr) second phase is formed in the aluminum alloy ingot during homogenization heat treatment, thereby further improving the strength and toughness of the rare earth aluminum alloy sheet.

[0019] Specific embodiment three: a preparation method of a rare earth aluminum alloy sheet according to the following steps:

[0020] I. According to the element mass percentage of 4.2-5.0% of Mg, 0.14-0.20% of Mn, 0.12-0.20% of Sc, 0.10-0.13% of Zr, 0.05-0.15% of Ti and the balance of Al, the raw materials are weighed in proportion, and then casting is carried out to obtain a rare earth aluminum alloy ingot;

[0021] II. The aluminum alloy ingot is homogenized at 340-360℃ for 16-18h, then heated to 440-460℃ for 10-14h, and then sequentially subjected to hot rough rolling treatment and hot finish rolling treatment to obtain a hot finish rolling coil; wherein the number of passes of the hot rough rolling treatment is 17-19 passes, the sum of the reduction rates of each pass is 94-95.5%, and the rolling speed is 1.50-3.00m·s -1 ; the number of passes of the hot finish rolling treatment is 3 passes, the reduction rates of each pass are 30-45% respectively, and the rolling speed is 2.00-3.00m·s -1 ; then the hot finish rolling coil is uncoiled and cut into pieces, and annealing treatment is carried out to obtain a rare earth aluminum alloy plate.

[0022] In the embodiment, the aluminum alloy ingot is subjected to homogenization heat treatment, and the microstructure of the alloy is controlled by the homogenization heat treatment, so that fine and dispersed Al3(Sc, Zr) second phases are formed in the alloy, which helps to improve the strength and toughness of the rare earth aluminum alloy plate. Through hot rolling treatment and annealing treatment, a large number of stable subgrain structures can be formed in the rare earth aluminum alloy plate, which helps to further improve the comprehensive performance of the rare earth aluminum alloy plate, such as strength, corrosion resistance and toughness. Therefore, the rare earth aluminum alloy plate prepared by the above method has important application value in the structure of the aircraft nose, lip, leading edge, wing and straight section fuselage, and can replace the 2xxx series alloy such as 2024 and 2524 in situ, which helps to reduce the weight of the aircraft and prolong the service life of the aircraft.

[0023] In the embodiment, the temperature of the annealing treatment is too high, which is not conducive to controlling the distribution and size of the nanoscale Al3(Sc, Zr) dispersed phase, and the Al3(Sc, Zr) dispersed phase will be obviously coarsened. If the temperature of the annealing treatment is too low, it is not conducive to improving the toughness of the rare earth aluminum alloy plate. Therefore, the temperature and holding time of the annealing treatment are preferably controlled within the above range, which helps to improve the elongation of the rare earth aluminum alloy plate while maintaining high yield strength and tensile strength, thereby improving the comprehensive performance of the rare earth aluminum alloy plate.

[0024] The temperature of the homogenization heat treatment is too high to refine the grains, and the temperature of the homogenization heat treatment is too low to fully release the stress inside the material. Preferably, the temperature and the holding time of the homogenization heat treatment are controlled in the above range, which helps to improve the defects inside the alloy structure, eliminate the stress, and refine the Al3(Sc, Zr) second phase, thereby helping to improve the strength and toughness of the rare earth aluminum alloy plate.

[0025] The material after the homogenization heat treatment is subjected to heating treatment, which helps to improve the plasticity of the material and reduce the deformation resistance. The material is subjected to preliminary processing and plastic shaping through the hot rough rolling treatment, which helps to refine the structure, eliminate the defects of the material, and make the structure more homogenized. The size of the material is accurately controlled through the hot finish rolling treatment, which improves the quality of the material surface, improves the uniformity of the structure distribution, and further refines the grains, thereby helping to improve the strength and toughness of the rare earth aluminum alloy plate.

[0026] Preferably, the temperature and the holding time of the heating treatment are controlled in the above range, which helps to further improve the plasticity of the material and reduce the deformation resistance. Preferably, the pass number, the rolling speed, and the processing rate of the hot rough rolling treatment are controlled in the above range, which helps to further refine the structure, eliminate the defects of the material, and make the structure more homogenized. Preferably, the pass number, the rolling speed, and the processing rate of the hot finish rolling treatment are controlled in the above range, which helps to further improve the quality of the material surface, improve the uniformity of the structure distribution, and further refine the grains, thereby helping to further improve the strength and toughness of the rare earth aluminum alloy plate.

[0027] Specific embodiment four: The embodiment is different from one of the specific embodiments one to three in that the mass ratio of the Sc element to the Zr element in the raw materials weighed in step one is 1.36-1.55:1. The others are the same as one of the specific embodiments one to three.

[0028] Specific embodiment five: The embodiment is different from one of the specific embodiments one to four in that the temperature of the homogenization heat treatment in step two is 350℃, and the holding time is 16h. The others are the same as one of the specific embodiments one to four.

[0029] Specific embodiment six: The embodiment is different from one of the specific embodiments one to five in that the heating temperature in step two is 450℃, and the holding time is 10h. The others are the same as one of the specific embodiments one to five.

[0030] Specific embodiment seven: The embodiment is different from one of the specific embodiments one to six in that the temperature of the annealing treatment in step two is 250-300℃, and the holding time of the annealing treatment is 1.5-3h. The others are the same as one of the specific embodiments one to six.

[0031] Embodiment eight: different from any one of the embodiments one to seven is that the annealing temperature in step two is 300℃, and the holding time of the annealing treatment is 2h. The others are the same as any one of the embodiments one to seven.

[0032] Embodiment nine: different from any one of the embodiments one to eight is that the annealing temperature in step two is 250℃, and the holding time of the annealing treatment is 2h. The others are the same as any one of the embodiments one to eight.

[0033] Embodiment ten: different from any one of the embodiments one to nine is that the yield strength of the rare earth aluminum alloy plate is 260-288MPa, the tensile strength is 352-378MPa, the elongation is 13.3-18.8%, and the fracture toughness Kc is 143-168MPa·m 1 / 2 . The others are the same as any one of the embodiments one to nine.

[0034] The beneficial effects of the present application are verified by the following examples:

[0035] Example 1

[0036] A preparation method of a rare earth aluminum alloy plate is carried out according to the following steps:

[0037] In the aluminum alloy ingot, the content of Mg element is 4.8wt%, the content of Mn element is 0.18wt%, the content of Sc element is 0.17wt%, the content of Zr element is 0.11wt%, the content of Ti element is 0.07wt%, the content of single impurity is not more than 0.05wt%, and the rest is Al. The above aluminum alloy ingot is subjected to homogenization heat treatment, the temperature of the homogenization heat treatment is 350℃, and the holding time is 16h. Then, the hot rolling treatment is carried out, wherein the temperature of the heating treatment before the hot rolling is 450℃, and the holding time is 10h. The hot rough rolling is carried out after discharging, and the hot rough rolling is carried out for 19 times. The rolling speed of the hot rough rolling is 2.00m·s -1 . The sum of the processing rate of each pass in the hot rough rolling is 94%, and the rolling is carried out to 24mm in thickness. Then, the hot finishing rolling is carried out for 3 times. The rolling speed of the hot finishing rolling is 3.00m·s -1 . The processing rate of each pass is 45%, and the air cooling is carried out to room temperature. The hot finishing rolling coiled material as shown in Figure 1 is obtained. The hot finishing rolling coiled material is uncoiled and cut into pieces. The length of each plate piece is 4000mm. The plate piece is subjected to annealing treatment. The annealing temperature is 250℃, and the holding time of the annealing treatment is 2h. The rare earth aluminum alloy plate as shown in Figure 2 is obtained.

[0038] Example 2

[0039] The difference from example 1 is that the number of passes of the hot rough rolling is 17 passes, the sum of the reduction rate of each pass of the hot rough rolling is 95.5%, and the rolling thickness is 24 mm, the reduction rate of each pass of the hot finish rolling is 30%, and finally the rare earth aluminum alloy plate is obtained.

[0040] Example 3

[0041] The difference from example 1 is that the annealing temperature is 300℃, the holding time of the annealing treatment is 2h, and finally the rare earth aluminum alloy plate is obtained.

[0042] Example 4

[0043] The difference from example 3 is that the number of passes of the hot rough rolling is 17 passes, the sum of the reduction rate of each pass of the hot rough rolling is 95.5%, and the rolling thickness is 24 mm, the reduction rate of each pass of the hot finish rolling is 30%, and finally the rare earth aluminum alloy plate is obtained.

[0044] Example 5

[0045] The difference from example 1 is that the content of Sc element is 0.15wt%, the content of Zr element is 0.11wt%, and the mass ratio of Sc element to Zr element is 1.36:1, and finally the rare earth aluminum alloy plate is obtained.

[0046] Example 6

[0047] The difference from example 1 is that the content of Mg element is 4.6wt%, the content of Mn element is 0.19wt%, the content of Sc element is 0.15wt%, the content of Zr element is 0.12wt%, and the content of Ti element is 0.06wt%, and finally the rare earth aluminum alloy plate is obtained.

[0048] Example 7

[0049] The difference from example 1 is that the content of Mg element is 4.9wt%, the content of Mn element is 0.15wt%, the content of Sc element is 0.18wt%, the content of Zr element is 0.11wt%, and the content of Ti element is 0.12wt%, and finally the rare earth aluminum alloy plate is obtained.

[0050] Example 8

[0051] The difference from example 1 is that the content of Mg element is 4.2wt%, the content of Mn element is 0.20wt%, the content of Sc element is 0.12wt%, the content of Zr element is 0.13wt%, and the content of Ti element is 0.05wt%, and finally the rare earth aluminum alloy plate is obtained.

[0052] Example 9

[0053] The difference from Example 1 is that the content of Mg is 5.0 wt%, the content of Mn is 0.14 wt%, the content of Sc is 0.20 wt%, the content of Zr is 0.10 wt%, and the content of Ti is 0.15 wt%, and the rare earth aluminum alloy plate is finally obtained.

[0054] Example 10

[0055] The difference from Example 1 is that the annealing temperature is 400℃ and the annealing time is 1 hour, finally obtaining a rare earth aluminum alloy sheet.

[0056] Example 11

[0057] The difference from Example 1 is that the homogenization heat treatment temperature is 360°C, the holding time of the homogenization heat treatment is 16h, the heating treatment temperature is 460°C, the holding time of the heating treatment is 10h, and finally a rare earth aluminum alloy plate is obtained.

[0058] Example 12

[0059] The difference from Example 1 is that the homogenization heat treatment temperature is 340°C, the holding time of the homogenization heat treatment is 18h, the heating treatment temperature is 440°C, the holding time of the heating treatment is 14h, and finally a rare earth aluminum alloy plate is obtained.

[0060] Example 13

[0061] The difference from Example 1 is that the homogenization heat treatment temperature is 370°C, the holding time of the homogenization heat treatment is 15h, the heating treatment temperature is 470°C, the holding time of the heating treatment is 9h, and finally a rare earth aluminum alloy plate is obtained.

[0062] Example 14

[0063] The difference from Example 1 is that the rolling speed for the hot roughing process is 1.50 m / s. -1 The rolling speed for hot finishing is 3.00 m / s. -1 The final product is a rare earth aluminum alloy sheet.

[0064] Example 15

[0065] The difference from Example 1 is that the rolling speed for the hot roughing process is 3.00 m / s. -1 The rolling speed for hot finishing is 2.00 m / s. -1 The final product is a rare earth aluminum alloy sheet.

[0066] Comparative Example 1

[0067] The difference from Example 1 is that no annealing treatment is performed, and the final product is a rare earth aluminum alloy sheet.

[0068] Comparative Example 2

[0069] The difference from Example 2 is that no annealing treatment is performed, and the final product is a rare earth aluminum alloy sheet.

[0070] Comparative Example 3

[0071] The difference from Example 1 is that the content of Mg is 4.0 wt%, the content of Mn is 0.30 wt%, the content of Sc is 0.30 wt%, the content of Zr is 0.05 wt%, and the content of Ti is 0.2 wt%, and the rare earth aluminum alloy plate is finally obtained.

[0072] Comparative Example 4

[0073] The difference from Example 1 is that Sc and Zr elements are not added, and rare earth aluminum alloy sheet is finally obtained.

[0074] The rare earth aluminum alloy plates prepared in the above embodiments and comparative examples were tested for yield strength, tensile strength, elongation and fracture toughness Kc. The yield strength, tensile strength and elongation were sampled and tested according to GB / T228 Metallic Materials, Room Temperature Tensile Test Method, and the fracture toughness Kc was tested according to HB5261. The test results are shown in Table 1.

[0075] Table 1

[0076]

[0077]

[0078] As shown in Table 1, with the increase of hot roughing rolling rate, the hot finishing rolling rate decreases, the yield strength and tensile strength of the alloy decrease, and the elongation increases slightly. With the increase of annealing temperature, the yield strength and tensile strength of the alloy decrease, and the elongation increases slightly, with no significant overall change. Annealing at 250℃ and 300℃ for 2 hours respectively yields a good balance of strength and toughness. The yield strength of the rare earth aluminum alloy sheet is 260–288 MPa, the tensile strength is 352–378 MPa, the elongation is 13.3–18.8%, and the fracture toughness Kc is 143–168 MPa·m. 1 / 2 .

[0079] Figure 3 This is a microstructure diagram of the rare earth aluminum alloy sheet in Example 1 of this application. Figure 3 It can be seen from the data that no recrystallization occurred in the rare earth aluminum alloy sheet; Figure 4 This is a microstructure diagram of the rare earth aluminum alloy sheet in Comparative Example 4 of this application. Figure 4It can be seen that rare earth aluminum alloy plates without added Sc and Zr elements exhibit some recrystallization. This suggests that adding appropriate amounts of Sc and Zr elements to rare earth aluminum alloy plates to form dispersed nano-sized Al3(Sc, Zr) helps to suppress recrystallization.

[0080] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0081] The addition of Mg to the rare-earth aluminum alloy sheet of this application helps to improve the strength and stiffness of the rare-earth aluminum alloy sheet while reducing its density. The addition of Mn helps to improve the strength, plasticity, and corrosion resistance of the rare-earth aluminum alloy sheet. The addition of Sc and Zr helps to form fine and dispersed Al3(Sc,Zr) second phase during the homogenization heat treatment of the aluminum alloy ingot, thereby helping to improve the strength and toughness of the rare-earth aluminum alloy sheet. The addition of Ti helps to improve the strength, corrosion resistance, and heat resistance of the rare-earth aluminum alloy sheet. Preferably, controlling the mass percentages of Mg, Mn, Sc, Zr, and Ti within the above-mentioned ranges helps to enhance the synergistic effect between the elements, thereby further improving the overall performance of the rare-earth aluminum alloy sheet, including its strength, corrosion resistance, and toughness. The rare earth aluminum alloy sheet of this application has important application value in the structure of aircraft such as nose, lip, leading edge, wing, and straight fuselage. It can replace the application parts of 2xxx series alloys such as 2024 and 2524 in situ, thereby helping to reduce the weight of the aircraft and extend its service life.

Claims

1. A method for preparing a rare earth aluminum alloy sheet, characterized in that... The preparation method is carried out according to the following steps:

1. Weigh the raw materials according to the following proportions: Mg 4.8%, Mn 0.18%, Sc 0.17%, Zr 0.11%, Ti 0.07%, and Al balance. Then cast the raw materials to obtain rare earth aluminum alloy ingots.

2. The aluminum alloy ingot is subjected to homogenization heat treatment at 340–360℃ for 16–18 hours, then heated to 440–460℃ and held for 10–14 hours, followed by hot rough rolling and hot finish rolling to obtain hot-finished coils. The hot rough rolling process consists of 17–19 passes, with a total processing yield of 94–95.5% for each pass, and a rolling speed of 1.50–3.00 m / s. -1 The hot finishing process consists of three passes, with each pass having a processing rate of 30-45%, and a rolling speed of 2.00-3.00 m / s. -1 Then, the hot-rolled coil is uncoiled, cut into pieces, and annealed to obtain rare earth aluminum alloy sheets.

2. The method for preparing a rare earth aluminum alloy sheet according to claim 1, characterized in that... In step two, the homogenization heat treatment temperature is 350℃ and the holding time is 16h.

3. The method for preparing a rare earth aluminum alloy sheet according to claim 1, characterized in that... Step 2: Heat to 450℃ and keep warm for 10 hours.

4. The method for preparing a rare earth aluminum alloy sheet according to claim 1, characterized in that... The annealing temperature for step two is 250–300℃, and the holding time for annealing is 1.5–3 hours.

5. The method for preparing a rare earth aluminum alloy sheet according to claim 1, characterized in that... The annealing temperature in step two is 300℃, and the holding time for the annealing treatment is 2 hours.

6. The method for preparing a rare earth aluminum alloy sheet according to claim 1, characterized in that... The annealing temperature in step two is 250℃, and the holding time for the annealing treatment is 2 hours.

7. The method for preparing a rare earth aluminum alloy sheet according to claim 1, characterized in that... The rare earth aluminum alloy sheet has a yield strength of 260–288 MPa, a tensile strength of 352–378 MPa, an elongation of 13.3–18.8%, and a fracture toughness Kc of 143–168 MPa·m. 1 / 2 .

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