Preparation method of 2xxx series aluminum alloy coated sheet for aviation

Abstract

The invention discloses a preparation method of a 2xxx series aluminum alloy coated thin plate for aviation, which comprises the following steps: (1) sawing and milling a homogenized 2xxx series aluminum alloy cast ingot to obtain a cast ingot with a smooth surface, and taking the cast ingot as a core material; (2) determining the size specification of the coating material 1xxx series aluminum alloy, brushing and grinding the coating surface of the coating material, and then cleaning and drying the coating surface of the coating material; (3) the cladding material obtained in the step (2) is attached to a core material, the cladding material and the core material are fixed through a spot welding and riveting combined method, and a composite cast ingot fixed into a whole is obtained; and (4) the composite cast ingot obtained in the step (3) is subjected to hot rolling, cold rolling and annealing, and the 2xxx series aluminum-clad sheet is obtained. The cladding material and the core material are fixed in a spot welding and riveting combined mode, the roughness of the cladding surface of the cladding material is controlled, the cladding material and the core material are firmly attached, and the hot rolling welding effect is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy thin plate preparation, and particularly relates to a preparation method for 2xxx series aluminum alloy clad thin plates for aviation. Background Art

[0002] The 2xxx series aluminum alloy belongs to the Al-Cu-Mg series alloy and is a heat-treatable strengthened high-strength aluminum alloy. Due to its high specific strength, good high-temperature stability and welding performance, etc., it is often used as the fuselage skin material in the aerospace field. In order to further meet the usage requirements of the 2xxx series aluminum alloy in the harsh environments of aviation and aerospace, a layer of high-purity aluminum can be clad on the alloy surface to improve the corrosion resistance of the alloy. The generally selected materials for high-purity aluminum are 1050 aluminum alloy or 1230 aluminum alloy. The cladding process is in the early stage of hot rolling, specifically, the high-purity aluminum is fixed to the milled matrix structure by welding or pinning, and after processes such as hot rough rolling and hot finish rolling, it is clad on the alloy surface. Cladding a layer of high-purity aluminum on the surface of the 2xxx series aluminum alloy can not only physically protect the alloy matrix, but also act as an anode due to its own high electrode potential for anodic protection. However, there are still some problems in the preparation of the 2xxx series clad thin plate materials at present. If only spot welding is used for fixing, during transportation, it is necessary to carry out steel strip packing to avoid the risk of falling off. The steel strip is likely to leave marks on the surface, and during the rolling process, spot welding cracking may also occur, resulting in poor welding between the cladding material and the core material. And if only riveting is used for fixing, although the fixing is firm, this method requires secondary processing and the process is cumbersome. Based on this, a preparation method for 2xxx series aluminum alloy clad thin plates for aviation is studied. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a preparation method for 2xxx series aluminum alloy clad thin plates for aviation, which improves the welding performance between the core material and the cladding material by combining spot welding and riveting.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A preparation method for 2xxx series aluminum alloy clad thin plates for aviation, comprising the steps of:

[0006] (1) Saw and mill the 2xxx series aluminum alloy ingot after homogenization treatment to obtain a smooth-surface ingot as the core material;

[0007] (2) Determine the size specifications of the 1xxx series aluminum alloy as the cladding material according to the size of the 2xxx series aluminum alloy ingot of the core material, brush and grind the cladding surface of the cladding material, and then clean and dry the cladding surface of the cladding material;

[0008] (3) Bond the cladding material obtained in step (2) to the core material, and fix the cladding material and the core material by a method combining spot welding and riveting to obtain a composite ingot fixed as a whole.

[0009] (4) Subject the composite ingot obtained in step (3) to hot rolling, cold rolling, and annealing to obtain 2xxx series aluminum-clad sheets.

[0010] Further, the homogenization process of the 2xxx series aluminum alloy ingot in step (1) is as follows: the homogenization temperature is 490 - 496 °C, the homogenization time is 20 - 24 h, and after homogenization, it is cooled to room temperature at a cooling rate of not less than 70 - 150 °C / h.

[0011] Further, when sawing the ingot in step (1), the gate end is sawed by 1.50 - 3.0%, and the expanded end is sawed by 4.0 - 5.0%; when milling the ingot, both the upper and lower surfaces of the ingot are milled by 3.5 - 5.0%.

[0012] In the above technical solution, the present invention controls the milling amount to remove segregation problems such as the coarse grain layer of the ingot, ensures that the grain structure of the transition zone where the cladding material and the core material are welded is uniform, and improves the welding effect.

[0013] Further, the surface roughness of the cladding surface of the cladding material after brushing in step (2) is 1.5 - 2.5 μm.

[0014] In the above technical solution, by brushing the cladding surface of the cladding material, the present invention not only removes the surface oxide layer of the cladding surface, but also controls its surface roughness within a certain range, which can increase the contact area between the cladding material and the core material and improve the welding performance of the cladding material and the core material during hot rolling; however, the surface roughness of the cladding surface should not be too large, otherwise, it is difficult to completely remove the cleaning agent on the cladding surface, resulting in defects such as poor welding between the cladding material and the core material; in addition, if the surface roughness of the cladding surface is too large, it may also affect the flow performance of the cladding material during hot rolling, resulting in uneven cladding layers, and even affecting the cladding area, resulting in the cladding layer not completely covering the core material.

[0015] Further, for the 2xxx series aluminum-clad sheets with a finished product thickness of 1.60 - 3.50 mm in step (2), the nominal cladding rate is set to 4.0%, and the minimum cladding rate is not less than 2.5%; and the thickness of the cladding material is 15 - 25 mm, the width of the cladding material is (width of the effective rolling surface of the core material - (20 ± 15 mm) × 2), and the length is (length of the core material - (200 ± 10 mm) × 2).

[0016] Further, when the cladding material and the core material are fixed in step (3), the spot welding positions and the riveting positions are arranged on both side edges of the cladding material. The spot welding positions and the riveting positions on each side are alternately and evenly distributed, and the spot welding position or the riveting position at the outermost end is 20 - 50 mm away from the end edge of the cladding material.

[0017] In the above technical solution, the present invention uses a combination of spot welding and riveting to fix the cladding material and the core material, and the spot welding positions and the riveting positions on each side are alternately and evenly distributed, which can make the cladding material and the core material firmly combined, and make the adhesion and fastening between them more firm, avoiding the adverse effects caused by the packing steel strip during the hot rolling process.

[0018] Further, when the cladding material and the core material are fixed in step (3), the spot welding and riveting positions are adjusted according to the lengths of the cladding material and the core material, and the distance between the spot welding position and the riveting position is controlled to be 500 mm - 1000 mm.

[0019] Further, when the cladding material and the core material are fixed in step (3), the materials of the welding wire and the rivets used for the spot welding positions and the riveting positions are the same as the material of the core material.

[0020] Further, the specific processes of hot rolling and cold rolling in step (4) are as follows: The composite ingot is put into a heating furnace and heated to 430 - 450 °C, and after heat preservation for 2 - 5 h, hot rolling is carried out. The number of hot rolling passes is 20 - 25 passes; among them, the reduction in the first two passes is 1 - 4 mm, and the rolling speed is 0.35 - 0.5 m / s for the welding rolling of the composite ingot; In the third pass, emulsion spraying is started, with the spraying amount on the upper surface being 15 - 25% and the spraying amount on the lower surface being 40 - 55%. In the 10th pass or the 13th pass, the emulsion spraying amount is increased to 35 - 45% on the upper surface and 70 - 80% on the lower surface. Starting from the 4th pass, the reduction in each pass is controlled to be ≤ 30 mm, the rolling speed is ≤ 2.0 m / s, and the final rolling temperature is controlled at 300 - 330 °C. The thickness of the hot-rolled finished product is 4.0 - 7.0 mm; Then the hot-rolled finished product blank is cold-rolled through 2 - 4 passes to the target thickness, ensuring that the cold rolling deformation rate is 50 - 80%, and finally a 2xxx series aluminum-clad thin sheet with a thickness of 1.60 - 3.50 mm is obtained.

[0021] Further, the annealing process in step (4) is as follows: The annealing temperature is 380 - 385 (±3) °C, and the annealing time is 25 ± 5 s.

[0022] The beneficial effects of the present invention are as follows:

[0023] The present invention provides a preparation method of a 2xxx series aluminum alloy clad sheet for aviation. The clad material and the core material are fixed by a combination of spot welding and riveting, and the roughness of the clad surface of the clad material is controlled, so that the contact area between the clad material and the core material is large and the contact is firm, ensuring the hot rolling welding effect. This can not only prevent delamination and cracking of the clad layer and the core material during rolling or use, but also the clad layer of the 2xxx series aluminum alloy clad sheet prepared by the preparation method of the present invention has a uniform thickness and good cladding effect. At the same time, the mechanical properties are ensured, preventing uneven or degraded mechanical properties caused by poor welding between the clad material and the core material or uneven clad layer thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 Schematic diagram of the fixing method of the clad material and the core material in Embodiment 1 of the present invention;

[0026] Figure 2 Metallographic photo of the annealed 2xxx series aluminum-clad sheet prepared in Embodiment 1 of the present invention;

[0027] Figure 3 Metallographic photo of the upper surface clad layer and the transition region of the annealed 2xxx series aluminum-clad sheet prepared in Embodiment 1 of the present invention;

[0028] Figure 4 Metallographic photo of the lower surface clad layer and the transition region of the annealed 2xxx series aluminum-clad sheet prepared in Embodiment 1 of the present invention;

[0029] Figure 5 Metallographic photo of the upper surface clad layer and the transition region of the annealed 2xxx series aluminum-clad sheet prepared in Comparative Example 3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The present invention provides a preparation method of a 2xxx series aluminum alloy clad sheet for aviation. To make the purpose, technical solutions and effects of the present invention clearer and more definite, the present invention will be further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] Embodiment 1

[0032] In this embodiment, a 2xxx series aluminum alloy clad sheet for aviation is prepared, and the steps are as follows:

[0033] (1) The 2xxx series aluminum alloy ingots are produced by semi - continuous casting using large - sized flat ingots with specifications of 400 mm (thickness) × 1800 mm (width) × 4000 mm (length). The alloy composition (mass fraction / wt.%) is Si: 0.23, Fe: 0.40, Cu: 3.93, Mn: 0.33, Mg: 1.25, Cr: 0.08, Zn: 0.18, Ti: 0.03. After casting, the ingots are put into a homogenizing furnace for single - stage homogenization treatment at 493 °C for 23 h. After the homogenization heat treatment is completed, they are cooled to room temperature at a cooling rate of 80 °C / h. The gate end of the homogenized 2xxx series aluminum alloy ingots is sawed off 150 mm of waste ingots, and the expansion end is sawed off 300 mm of waste ingots. 18 mm of segregation layers are milled off from the upper and lower surfaces of the ingots, and 5 mm of segregation layers are milled off from the side surfaces of the ingots, obtaining surface - smooth ingots with specifications of 364 mm (thickness) × 1790 mm (width) × 3550 mm (length) as the core material;

[0034] (2) Determine the size specifications of the 1050 aluminum alloy cladding material according to the size of the core 2xxx series aluminum alloy ingots. Design the cladding rate to be 3.0%. Determine that the thickness of the 1050 aluminum alloy cladding material is 20 mm, the width is 1730 mm, and the length is 3150 mm. Brush and grind the cladding surface of the cladding material to remove the surface oxide layer, and at the same time control its surface roughness to be 1.7 μm to increase the contact area. After brushing and grinding, use an oil - free towel or oil - free paper to dip in methyl ethyl ketone or acetone cleaning agent to wipe the brushed and ground surface, and then use a clean oil - free towel or oil - free paper to wipe the brushed and ground surface to remove the residual methyl ethyl ketone or acetone on the surface, keeping the cladding surface dry;

[0035] (3) Use 1050 aluminum alloy to carry out cladding treatment on the core material. Fit the cladding material and the core material, and use a method combining spot welding and riveting to fix the cladding material and the core material, obtaining a composite ingot fixed as a whole. And the welding wire and rivets used for spot welding and riveting have the same material as the core material. Specifically, as Figure 1 shown, the spot - welding positions and riveting positions are set on both side edges of the cladding material. The spot - welding positions and riveting positions on each side are alternately and evenly distributed along the length direction of the cladding material. The spot - welding position or riveting position at the outermost end of each side is 50 mm away from the end edge of the cladding material, and the distance between adjacent two spot - welding positions and riveting positions is 610 mm;

[0036] (4) Put the composite ingot into a heating furnace for preheating before hot rolling at 435°C for 2.5 h. After heating, conduct hot rolling. Set the number of hot rolling passes to 22. Among them, the reduction in the 1st and 2nd passes is 2 mm, and the rolling speed is 0.35 m / s; in the 3rd pass, emulsion spraying is started, with the spraying amount on the upper surface being 15% and the spraying amount on the lower surface being 40%; after the 4th pass, control the reduction per pass ≤ 30 mm and the rolling speed ≤ 2.0 m / s; and increase the emulsion spraying amount to 35% on the upper surface and 70% on the lower surface in the 10th pass; control the final rolling temperature at 330°C, and the thickness of the hot-rolled finished product is 7.0 mm; then cold roll the hot-rolled finished product blank in 2 passes to the target thickness of 3.2 mm, where the reduction in the 1st pass is 2.2 mm and the reduction in the 2nd pass is 1.6 mm, and control the rolling speed at 0.40 m / s to finally obtain a cold-rolled finished product with a thickness of 3.2 mm; then conduct continuous annealing treatment on the cold-rolled finished product in a cushion-type continuous annealing furnace at 383°C for 24 s to obtain a 2xxx series aluminum-clad sheet in a fully recrystallized annealed state.

[0037] Perform mechanical property tests on the annealed 2xxx series aluminum-clad sheet prepared in this example. Its tensile strength is 180 MPa, yield strength is 90 MPa, and elongation is 33%, meeting the usage standards of 2xxx series aviation aluminum materials, and the cladding effect of the formed cladding layer is uniform.

[0038] Perform metallographic inspection on the annealed 2xxx series aluminum-clad sheet prepared in this example, as Figures 2-4 shown. It can be seen from Figures 2-4 that: the thickness of the cladding layer of the 2xxx series aluminum-clad sheet prepared in this example is uniform, the transition region between the cladding layer and the core material is well welded, and there are no defects such as cracks, slag inclusions, and pores.

[0039] Example 2

[0040] Prepare a 2xxx series aluminum alloy clad sheet for aviation in this example, and the steps are as follows:

[0041] (1) The 2xxx series aluminum alloy ingots adopt large-sized flat ingots with specifications of 480 mm (thickness) × 2000 mm (width) × 5000 mm (length), and are produced by semi-continuous casting. The alloy composition is (mass fraction / wt.%) Si: 0.19, Fe: 0.28, Cu: 4.63, Mn: 0.53, Mg: 1.56, Cr: 0.05, Zn: 0.10, Ti: 0.05. After casting, the ingots are put into a homogenizing furnace for single-stage homogenization treatment at 496 °C for 20 h. After the homogenization heat treatment is completed, they are cooled to room temperature at a cooling rate of 140 °C / h. The gate end of the homogenized 2xxx series aluminum alloy ingots is sawed off by 200 mm of waste ingots, and the expansion end is sawed off by 350 mm of waste ingots. 25 mm of segregation layer is milled off from the upper and lower surfaces of the ingots, and 8 mm of segregation layer is milled off from the side surfaces of the ingots to obtain a surface-smooth ingot with specifications of 430 mm (thickness) × 1984 mm (width) × 4450 mm (length) as the core material;

[0042] (2) Determine the size specifications of the 1050 aluminum alloy cladding material according to the size of the core 2xxx series aluminum alloy ingots. Design the cladding rate to be 3.5%, and determine that the thickness of the 1050 aluminum alloy cladding material is 25 mm, the width is 1924 mm, and the length is 4040 mm. Brush and grind the cladding surface of the cladding material to remove the surface oxide layer, and at the same time control its surface roughness to be 2.3 μm to increase the contact area. After brushing and grinding, use a non-oily towel or non-oily paper to dip in methyl ethyl ketone or acetone cleaning agent to wipe the brushed and ground surface, and then wipe the brushed and ground surface with a clean non-oily towel or non-oily paper to remove the remaining methyl ethyl ketone or acetone on the surface, so that the cladding surface remains dry;

[0043] (3) Use 1050 aluminum alloy to carry out cladding treatment on the core material. Fit the cladding material and the core material, and use a method combining spot welding and riveting to fix the cladding material and the core material to obtain a composite ingot fixed as a whole. The welding wire and rivets used for spot welding and riveting are of the same material as the core material. Specifically, the spot welding positions and riveting positions are set on both side edges of the cladding material, and the spot welding positions and riveting positions on each side are alternately and evenly distributed along the length direction of the cladding material. The spot welding position or riveting position at the outermost end of each side is 20 mm away from the end edge of the cladding material, and the distance between adjacent two spot welding positions and riveting positions is 800 mm;

[0044] (4) The composite ingot was placed in a heating furnace for preheating at 440°C for 4 hours before hot rolling. After the heating, hot rolling was carried out. The hot rolling passes were set to 25, of which the first and second passes had a reduction of 3.5 mm and a rolling speed of 0.35 m / s. The emulsion spraying was started in the third pass, with the upper surface spraying amount being 20% and the lower surface spraying amount being 50%. After the fourth pass, the reduction of each pass was controlled to be ≤30 mm and the rolling speed ≤2.0 m / s. The emulsion spraying amount was increased to 45% of the upper surface spraying amount and 75% of the lower surface spraying amount in the 13th pass. %; the final rolling temperature is controlled at 320°C, and the thickness of the hot-rolled product is 5.0 mm; the hot-rolled finished billet is then cold-rolled in three passes to a target thickness of 2.01 mm, wherein the first pass reduction is 1.1 mm, the second pass reduction is 1.2 mm, and the third pass reduction is 1.2 mm. The rolling speed is controlled at 0.35 m / s, and a cold-rolled product with a thickness of 2.01 mm is finally obtained; the cold-rolled product is then continuously annealed in an air cushion continuous annealing furnace at 380°C×22s to obtain a fully recrystallized annealed 2xxx series aluminum-clad sheet.

[0045] The mechanical properties of the annealed 2xxx series aluminum-clad thin plate prepared in this embodiment were tested, and the tensile strength was 175 MPa, the yield strength was 89 MPa, and the elongation was 38%, which met the use standards of 2xxx series aviation aluminum materials, and the coating effect of the formed coating layer was uniform.

[0046] Comparative Example 1

[0047] This comparative example 1 prepares a 2xxx series aluminum alloy clad sheet for aviation use. The difference between it and Example 1 is that this comparative example adopts a combination of spot welding and riveting to fix the cladding material and the core material, the spot welding positions are evenly distributed on one side edge of the cladding material, and the rivet positions are evenly distributed on the other side edge of the cladding material.

[0048] During the hot rolling process, the composite ingot of this comparative example had a warping problem at the spot welding position, while the riveting position was normally fixed, and thus failed to be rolled smoothly.

[0049] Comparative Example 2

[0050] In this comparative example 2, a 2xxx series aluminum alloy clad sheet for aviation is prepared. The difference between this comparative example and example 1 is that in this comparative example, only riveting is used to fix the cladding material and the core material, and the rivet positions are set at the two side edges of the cladding material and the rivet positions on each side are evenly distributed.

[0051] The mechanical properties of the annealed 2xxx series aluminum-clad thin sheet prepared in this comparative example were tested. Its tensile strength was 173 MPa, yield strength was 88 MPa, and elongation was 35%, meeting the usage standards of 2xxx series aviation aluminum materials, and the cladding effect of the formed cladding layer was uniform. However, riveting requires secondary processing of the core material and the cladding material, with cumbersome production processes and high production and manufacturing costs.

[0052] Comparative Example 3

[0053] In this Comparative Example 3, an aviation-use 2xxx series aluminum alloy clad thin sheet was prepared, and its difference from Example 1 was that: in this comparative example, the cladding surface of the cladding material was brushed, and the surface roughness after brushing was 5.0 μm.

[0054] Metallographic examination was carried out on the annealed 2xxx series aluminum-clad thin sheet prepared in this comparative example, as Figure 5 shown. It can be seen from Figure 5 that: the thickness of the cladding layer of the 2xxx series aluminum-clad thin sheet prepared in this comparative example was uneven, and the cladding effect was poor. If the thickness of the cladding layer is uneven, it is easy to cause stress corrosion during service, affecting the normal service performance of the alloy sheet.

[0055] The main reason for the uneven thickness of the cladding layer in the annealed 2xxx series aluminum-clad thin sheet prepared in this comparative example was that: the surface roughness of the contact surface between the core material and the cladding material was relatively high. During the rolling process, the metal on the inner surface of the cladding material had uneven flow due to relatively large frictional force, resulting in uneven thickness of the cladding layer.

[0056] Comparative Example 4

[0057] In this Comparative Example 4, an aviation-use 2xxx series aluminum alloy clad thin sheet was prepared, and its difference from Example 1 was that: in this comparative example, the cladding surface of the cladding material was brushed, and the surface roughness after brushing was 0.5 μm.

[0058] In this comparative example, during the rolling process, due to the relatively low surface roughness of the contact surface between the cladding material and the core material, the metal flow of the cladding layer was relatively fast under the normal rolling force with a reduction in thickness, resulting in a situation where the tail end of the clad sheet was too long. Moreover, the thickness of the finally prepared clad thin sheet was 1.9 mm, unable to reach the target thickness of 2.0 mm, resulting in a poor cladding effect of the formed cladding layer and not meeting the usage standards of 2xxx series aviation aluminum materials.

[0059] By analyzing the test results of the above-mentioned embodiments and comparative examples: In Example 1 of the present invention, the covering material and the core material are fixed by combining spot welding and riveting, and the roughness of the covering surface of the covering material is controlled, so that the contact area between the covering material and the core material is large and the contact is firm, ensuring the hot rolling welding effect and preventing delamination and cracking between the covering layer and the core material during use. The combined fixing method of spot welding and riveting in the present invention, in combination with the roughness of the covering surface, can achieve the same effect as that of Comparative Example 2 fixed only by the riveting method. However, the method of the present invention reduces the number of riveting positions, reduces the workload of secondary processing, and reduces the production cost.

[0060] It should be noted that the parts not described in the present invention can be realized by adopting or referring to the existing technologies.

[0061] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the scope of the essence of the present invention should also fall within the protection scope of the present invention.

Claims

1. A preparation method of a 2xxx series aluminum alloy clad sheet for aviation, characterized in that Including the steps: (1) Saw and mill the homogenized 2xxx series aluminum alloy ingot to obtain an ingot with a smooth surface as the core material; (2) Determine the size specifications of the cladding material of 1xxx series aluminum alloy according to the size of the core material of 2xxx series aluminum alloy ingot, brush and grind the cladding surface of the cladding material, and then clean and dry the cladding surface of the cladding material; (3) Fit the cladding material obtained in step (2) with the core material, and fix the cladding material and the core material by a method combining spot welding and riveting to obtain a composite ingot fixed as a whole; (4) Subject the composite ingot obtained in step (3) to hot rolling, cold rolling, and annealing to obtain a 2xxx series aluminum-clad sheet.

2. The preparation method of a 2xxx series aluminum alloy clad sheet for aviation according to claim 1, characterized in that The homogenization process of the 2xxx series aluminum alloy ingot in step (1) is: the homogenization temperature is 490 - 496 °C, the homogenization time is 20 - 24 h, and after homogenization, it is cooled to room temperature at a cooling rate of not less than 70 - 150 °C / h.

3. The preparation method of an aviation-used 2xxx series aluminum alloy clad sheet according to claim 1, characterized in that, When sawing the ingot in step (1), the gate end is sawed by 1.50 - 3.0%, and the expanded end is sawed by 4.0 - 5.0%; when milling the ingot in step (1), both the upper and lower surfaces of the ingot are milled by 3.5 - 5.0%.

4. The preparation method of a 2xxx series aluminum alloy clad sheet for aviation according to claim 1, characterized in that, The roughness of the cladding surface of the cladding material after brushing and grinding in step (2) is 1.5 - 2.5 μm.

5. The preparation method of a 2xxx series aluminum alloy clad sheet for aviation according to claim 1, characterized in that, In step (2), for the 2xxx series aluminum-clad sheet with a finished product thickness of 1.60 - 3.50 mm, the nominal cladding rate is set to 4.0%, and the minimum cladding rate is not less than 2.5%; and the thickness of the cladding material is 15 - 25 mm, the width of the cladding material is (width of the effective rolling surface of the core material - (20 ± 15 mm) × 2), and the length is (length of the core material - (200 ± 10 mm) × 2).

6. The preparation method of a 2xxx series aluminum alloy clad sheet for aviation according to claim 1, characterized in that, When fixing the cladding material and the core material in step (3), the spot welding positions and the riveting positions are set on both side edges of the cladding material, and the spot welding positions and the riveting positions on each side are alternately and evenly distributed, and the spot welding position or the riveting position at the outermost end is 20 - 50 mm away from the end edge of the cladding material.

7. The preparation method of a 2xxx series aluminum alloy clad sheet for aviation according to claim 6, characterized in that, When fixing the cladding material and the core material in step (3), control the distance between the spot welding positions and the riveting positions to be 500 mm - 1000 mm.

8. The preparation method of a 2xxx series aluminum alloy clad sheet for aviation according to claim 5, characterized in that, When fixing the cladding material and the core material in step (3), the materials of the welding wire and the rivets used at the spot welding positions and the riveting positions are the same as the material of the core material.

9. The preparation method of a 2xxx series aluminum alloy clad sheet for aviation according to claim 1, characterized in that, The specific processes of hot rolling and cold rolling in step (4) are as follows: Put the composite ingot into a heating furnace and heat it to 430 - 450 °C. After holding for 2 - 5 h, conduct hot rolling with 20 - 25 passes; among them, the reduction per pass for the first two passes is 1 - 4 mm, the rolling speed is 0.35 - 0.5 m / s for the welding rolling of the composite ingot; start spraying emulsion in the third pass, with the spraying amount on the upper surface being 15 - 25% and the spraying amount on the lower surface being 40 - 55%. Increase the emulsion spraying amount to 35 - 45% on the upper surface and 70 - 80% on the lower surface in the 10th or 13th pass. Starting from the 4th pass, control the reduction per pass ≤ 30 mm and the rolling speed ≤ 2.0 m / s, and control the final rolling temperature at 300 - 330 °C. The thickness of the hot-rolled finished product is 4.0 - 7.0 mm; then cold-roll the hot-rolled finished product blank through 2 - 4 passes to the target thickness, ensure that the cold rolling deformation rate is 50 - 80%, and control the rolling speed at 0.35 - 0.5 m / s to finally obtain a 2xxx series aluminum-clad thin sheet with a thickness of 1.60 - 3.50 mm.

10. The preparation method of a 2xxx series aluminum alloy clad sheet for aviation according to claim 1, characterized in that, The annealing process in step (4) is as follows: The annealing temperature is 380 - 385 (±3) °C, and the annealing time is 25 ± 5 s.

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