Preparation method of high-strength and high-plasticity multi-layer aluminum alloy plate

Abstract

The application discloses a preparation method of high-strength and high-plasticity multilayer aluminum alloy plate and belongs to the rolling technical field of composite layered metal materials. Main steps are as follows: a milled surface and homogenization treatment are conducted on a 7017 / 7055 ingot prepared by melting and blending; after surface treatment, the ingot blank is coated with a pure aluminum layer to prepare a pre-coated plate; rolling and compounding of the pre-coated plate are conducted at 440-475 DEG C; surface treatment is conducted on the obtained two pre-coated plates, the pre-coated plates are stacked and riveted, and rolling and compounding of the stacked and riveted pre-coated plates are conducted at 420-470 DEG C to prepare a laminated composite plate; after multi-pass rolling of the laminated composite plate, solid solution treatment and aging treatment are conducted to obtain a finished aluminum / aluminum laminated composite plate. The application reduces the number of composite layers of the finished laminated plate in the actual rolling process by preparing the pre-coated plate in advance, effectively controls the generation of surface bubbles, and simultaneously, the preparation method has low requirements on equipment, the laminated composite plate produced has good interface combination, and the mechanical properties and impact resistance are excellent. The method can provide technical support for the preparation of multilayer aluminum alloy composite materials.

Description

Technical Field

[0001] This invention belongs to the field of composite layered metal material rolling technology, specifically relating to a method for preparing high-strength, high-plasticity multilayer aluminum alloy plates. Background Technology

[0002] With rapid economic development and continuous social progress, there are increasingly higher requirements for lightweight, high-performance, multi-functional, and low-cost materials used in industries such as aerospace and special vehicles.

[0003] Aluminum alloys are among the most widely used non-ferrous metal structural materials in industry. Among them, 7xxx series aluminum alloys (Al-Zn-Mg and Al-Zn-Mg-Cu) are widely used in aerospace and special vehicles due to their high specific strength, low density, excellent weldability, and good machinability. However, due to the influence of alloy composition, it is difficult for a single 7xxx series aluminum alloy to simultaneously possess both high strength and high ductility, thus urgently requiring the development of new manufacturing processes. 7017 aluminum alloy belongs to the Al-Zn-Mg series, exhibiting good ductility but moderate to low strength. Although this alloy possesses excellent impact resistance, it may undergo plastic deformation before fully absorbing impact energy under high-speed impact or impact, thus failing to fully utilize its impact resistance. 7055 aluminum alloy belongs to the Al-Zn-Mg-Cu series and is currently the strongest deformable aluminum alloy, with good fracture toughness, strong resistance to fatigue crack propagation, and resistance to intergranular fracture and corrosion. However, this alloy has poor ductility, making it insufficient in absorbing impact energy and preventing crack propagation. Therefore, single 7017 or 7055 aluminum alloys are difficult to achieve ideal results in resisting high-speed impacts, which limits their application range and scenarios.

[0004] To address the aforementioned issues, this invention employs rolling technology to composite 7055 and 7017 alloys, enabling the hard 7055 alloy and the soft 7017 alloy to mutually constrain each other during deformation. This achieves complementary advantages in the strength and plasticity of the two alloys, resulting in an aluminum / aluminum laminated composite sheet with excellent comprehensive mechanical properties, providing a technical approach for improving the impact resistance of aluminum alloy sheets. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method for preparing a high-strength, high-ductility multilayer aluminum alloy plate with excellent mechanical properties and impact resistance. The technical solution adopted by this invention is as follows:

[0006] The method for preparing the high-strength, high-ductility multilayer aluminum alloy plate of the present invention is carried out according to the following steps:

[0007] (1) Preparation of the original ingots: Prepare 7017 aluminum alloy ingots and 7055 aluminum alloy ingots with the same area and thickness. Cut off the casting ends and bottoms of the ingots, and after milling the surface of the ingots, homogenize the two aluminum alloys. This reduces the compositional segregation that occurs during the casting process and prepares for the subsequent sheet rolling and thinning.

[0008] (2) Preparation of pre-clad plates: Prepare four 1050 aluminum alloy thin plates with dimensions larger than the ingots in step (1). After grinding, cleaning and drying the surfaces of the ingots and thin plates, 1050 aluminum plates are clad on both sides of the 7017 and 7055 aluminum alloy ingots by riveting to obtain 7017 and 7055 aluminum alloy pre-clad plates respectively. During riveting, the 1050 aluminum alloy thin plates, ingots and 1050 aluminum alloy thin plates are stacked alternately in the order of 1050 aluminum alloy thin plates. Holes are drilled on both sides of the plates and riveted with pure aluminum rivets. The holes do not need to penetrate the ingots.

[0009] (3) Pre-rolling and thinning of pre-coated plates: 7017 and 7055 pre-coated plates were rolled and thinned respectively. Stress-relief annealing was performed before rolling, and intermediate annealing was performed between rolling passes. The thickness ratio of 7017 pre-coated plate to 7055 pre-coated plate after thinning was 1:1 to 1:10.

[0010] (4) Trimming of pre-coated plates: Trim the rolled and thinned plates, select plates of appropriate size to avoid rivet positions, and roughen, clean and dry the surfaces of the two types of pre-coated plates.

[0011] (5) Surface cleaning of pre-coated boards: roughen, clean and dry the surfaces of the two types of pre-coated boards to remove surface stains.

[0012] (6) Fixing treatment of laminated composite panels: After cleaning, the pre-composite panels are stacked along the rolling direction in the order of 7017 pre-composite panels and 7055 pre-composite panels and then riveted to make the joint surfaces of the laminated panels contact and fix them.

[0013] (7) Rolling thinning of laminated composite plate: The fixed laminated plate is rolled. Stress relief annealing is performed before rolling. Intermediate annealing is performed between two passes during rolling to obtain a 7017 / 1050 / 7055 laminated composite plate with preliminary bonding.

[0014] (8) Preparation of laminated composite board: The laminated composite board is cut in half along the transverse direction of the board, and the operations of steps (5), (6), and (7) are repeated to perform one-pass cumulative rolling of composite.

[0015] (9) Heat treatment regime of laminated composite board: The laminated composite board is subjected to solution treatment in a box furnace and aging treatment in a drying oven.

[0016] In the above method, the composition of the 7017 aluminum alloy, by weight percentage, is: Si≤0.35%, Fe≤0.45%, Cu≤0.2%, 0.05%≤Mn≤0.50%, 2.0%≤Mg≤3.0%, Cr≤0.35%, Ni≤0.1%, 4.0%≤Zn≤5.2%, Ti≤0.15%, 0.10%≤Zr≤0.25%, Sc≤0.25%. The composition of 7055 aluminum alloy by weight percentage is: Si≤0.1%, Fe≤0.15%, 2.0%≤Cu≤2.6%, Mn≤0.05%, 1.8%≤Mg≤2.3%, Cr≤0.04%, 7.6%≤Zn≤8.4%, Ti≤0.06%, 0.08%≤Zr≤0.25%, Sc≤0.25%, with the balance being Al.

[0017] In the above method, the homogenization process in step (1) is a two-stage homogenization process. The first-stage homogenization process is: the board is heated in the furnace, and the furnace temperature is raised to 400℃ and then kept for 8 hours. The second-stage aging process is: the furnace temperature is raised to 460℃ and then kept for 36 hours.

[0018] In the above method, the treatment of all board surfaces is as follows: First, rinse the board with acetone to remove stains from the board surface. After air drying, roughen the pre-composite surface with a steel brush, and the scratches are distributed in a cross-shaped network. Then rinse the board with alcohol and then dry it with a hair dryer.

[0019] In the above method, when riveting the plates in step (2), 1050 aluminum alloy thin plates, ingots, and 1050 aluminum alloy thin plates are stacked alternately in that order. Holes are drilled on both sides of the plates and riveted with pure aluminum rivets to fix the four corners of the laminated composite plate together. The hole depth is 15mm and the length of the pure aluminum rivet is 20mm.

[0020] In the above method, the stress-relief annealing process in step (3) is to hold at 430℃~480℃ for 1.5h. The rolling thinning method of the pre-clad plate is as follows: the pre-clad plate is held at 440℃~480℃ for 1.5h. In order to prevent the aluminum cladding plate from shifting during rolling, the initial two passes have a reduction of 5%, and the remaining passes have a reduction of 20%~50%. Intermediate annealing is performed between passes at a temperature of 440℃~475℃ for 20min, but no intermediate annealing is performed before the last pass.

[0021] In the above method, during the riveting of the plates in step (6), holes are drilled at both ends of the plates and rivets are made with pure aluminum rivets to fix the four corners of the laminated composite plate together. The holes penetrate through the two pre-composite plates, and the length of the pure aluminum rivets is 25mm.

[0022] In the above method, the rolling thinning method of the laminated composite plate in steps (7) and (8) is as follows: the riveted laminated plate is subjected to stress-relief annealing at 430℃~475℃ and held for 1.5h. The reduction in each pass is 20%~50%, and intermediate annealing at 420℃~470℃ is performed between passes for 20min. The last pass is an exception, and intermediate annealing is not performed before it.

[0023] In the above method, the heat treatment regime of step (9) is divided into solution treatment and aging treatment. The solution treatment regime is as follows: the plate is heated in the furnace, the furnace temperature is raised to 470℃, and then held for 70 minutes, and then immediately water quenched. The aging treatment regime is as follows: the plate is heated in the furnace to 120℃, held for 24 hours, and then cooled to room temperature after being taken out.

[0024] Compared with the prior art, the features and beneficial effects of the present invention are as follows:

[0025] 1. In the preparation of 7017 / 1050 / 7055 aluminum alloy laminated composite plates, instead of fixing all the plates together for rolling at once, a method was adopted to first prepare 7017 aluminum alloy pre-clad plates and 7055 aluminum alloy pre-clad plates, and then composite rolling the 7017 aluminum alloy pre-clad plates and 7055 aluminum alloy pre-clad plates together. This reduced the number of composite layers in the finished laminated plate during the actual rolling process and effectively controlled the generation of surface bubbles.

[0026] 2. By employing hot rolling and single-pass cumulative rolling technology, along with appropriate heat treatment parameters, aluminum / aluminum laminated composite sheets with good interfacial bonding and strong impact resistance can be obtained. The process is simple and requires minimal equipment, providing a framework for large-scale industrial production.

[0027] This invention was supported by the 14th Five-Year Plan National Key Research and Development Program (Project No.: 2021YFB3701302). Attached Figure Description

[0028] Figure 1 This is a process flow diagram for the preparation of the aluminum / aluminum laminated composite plate of the present invention;

[0029] Figure 2 Metallographic images of the aluminum / aluminum laminated composite plates prepared in Examples 1-3 of this invention;

[0030] Figure 3 These are the stretching curves of Comparative Examples 1-2 and Examples 1-3 of the present invention. Detailed Implementation

[0031] The invention will be further illustrated below with specific examples.

[0032] A method for preparing a high-strength, high-ductility multilayer aluminum alloy plate, such as... Figure 1As shown, proceed with the following steps:

[0033] (1) Preparation of the original ingots: Melt and mix one 7017 and one 7055 aluminum alloy ingot each with a diameter of 175mm×150mm×46mm. Cut off 15mm from the ingot ends, 10mm from the bottom, and mill off 2-4mm from the surface. The processed ingots are subjected to a two-stage homogenization treatment. The first-stage homogenization treatment process is as follows: the plate is heated in the furnace, and the furnace temperature is raised to 400℃ and held for 8 hours. The second-stage aging treatment process is as follows: the furnace temperature is raised to 460℃ and held for 36 hours. This reduces the component segregation generated during the casting process and prepares for the subsequent plate rolling and thinning.

[0034] (2) Preparation of pre-clad plates: Prepare four 1050 aluminum alloy thin plates (155mm × 155mm × 1mm). Roughen the surfaces of the ingots and thin plates with a steel brush to create cross-scratches, then clean and dry. Use riveting to clad both sides of the 7017 and 7055 aluminum alloy ingots with 1050 aluminum plates to obtain 7017 and 7055 aluminum alloy pre-clad plates. When riveting the plates, stack the 1050 aluminum alloy thin plates, ingots, and 1050 aluminum alloy thin plates alternately. Drill holes on both sides of the plates and rivet them with pure aluminum rivets to fix the four corners of the laminated composite plate together. The hole depth is 15mm, and the pure aluminum rivet length is 20mm.

[0035] (3) Pre-rolling and thinning of pre-clad plates: 7017 and 7055 pre-clad plates were rolled and thinned respectively. Intermediate annealing was performed between rolling passes to obtain 7017 and 7055 alloy pre-clad plates with a thickness ratio of 1:1 to 1:10. The specific rolling and thinning method is as follows: the pre-clad plate is held at 440℃ to 480℃ for 1.5h. In order to prevent the aluminum cladding plate from shifting during rolling, the initial two passes have a reduction of 5%, and the remaining passes have a reduction of 20% to 50%. Intermediate annealing is performed between passes at a temperature of 440℃ to 475℃ for 20min, but no intermediate annealing is performed before the last pass.

[0036] (4) Trimming of pre-clad plates: Trim the rolled and thinned plates, selecting plates of appropriate size to avoid rivet locations. The dimensions of the trimmed 7017 alloy pre-clad plates and 7055 alloy pre-clad plates are both 200mm × 155mm, with the height being the thickness of the plate reduction.

[0037] (5) Surface cleaning of pre-coated boards: roughen, clean and dry the surfaces of the two types of pre-coated boards to remove surface stains.

[0038] (6) Fixing of the laminated composite panel: After cleaning, the pre-composite panels are stacked along the rolling direction in the order of 7017 pre-composite panels and 7055 pre-composite panels. Holes are drilled at the same position on the laminated panel blanks, and rivets are inserted into the holes to make the mating surfaces of each panel contact and fix them. When riveting the panels, holes are drilled at both ends of the panels and pure aluminum rivets are used to fix the four corners of the laminated composite panel together. The holes penetrate through the two pre-composite panels, and the length of the pure aluminum rivets is 25mm.

[0039] (7) Rolling thinning of laminated composite plate: Several laminated composite plates are rolled at room temperature, and intermediate annealing is carried out between rolling passes to make the thickness of the laminated composite plate 5mm.

[0040] (8) Preparation of laminated composite board: After removing the rivet-containing parts at the head and tail of the board, cut the resulting laminated composite board in half along the transverse direction to obtain a laminated board of 220mm×156mm×5mm. Repeat steps (5), (6), and (7) to perform one-pass cumulative rolling to obtain a laminated composite board with a thickness of 5mm.

[0041] In steps (7) and (8), the specific rolling thinning method for the laminated composite plate is as follows: the riveted laminated plate is subjected to stress-relief annealing at 430℃~475℃ and held for 1.5h. The reduction in each pass is 20%~50%, and intermediate annealing at 420℃~470℃ is performed between passes for 20min. The last pass is an exception, and intermediate annealing is not performed before it.

[0042] (9) Heat treatment regime of laminated composite board: The laminated composite board is subjected to solution treatment in a box furnace. The solution treatment regime is as follows: the board is heated with the furnace, and after the furnace temperature rises to 470℃, it is held for 70 minutes, and then immediately water quenched; the laminated composite board is subjected to aging treatment in a drying oven. The aging treatment regime is as follows: the board is heated with the furnace to 120℃, and then held for 24 hours, and then cooled to room temperature after being taken out.

[0043] Comparative Example 1

[0044] Fabrication of 5mm thick single 7017 aluminum alloy pre-clad plates

[0045] The mass percentage of the 7017 aluminum alloy ingot used is as follows: Si≤0.01%, Fe≤0.05%, Cu≤0.01%, Mn=0.28%, Mg=2.9%, Cr=0.12%, Ni≤0.01%, Zn=4.9%, Ti=0.005%, Zr=0.125%, Sc=0.25%, with the balance being Al. The ingot dimensions are 175mm×150mm×46mm.

[0046] Milling and homogenization of ingots: A 2-4 mm thick surface layer is milled off the aluminum alloy ingot using a milling machine, and a 10 mm section is cut off from the bottom of the ingot and a 15 mm section is cut off from the casting port using a saw. The treated ingot is then placed in a pit furnace for homogenization treatment. The homogenization treatment regime is as follows: the furnace temperature is raised to 400℃, held for 8 hours, and then the furnace temperature is raised to 460℃ and held for 36 hours.

[0047] Surface treatment and riveting of the pre-clad plate: Prepare two 155mm×155mm×1mm 1050 aluminum alloy sheets. Grind the surfaces of the ingot and the sheets to create cross-scratches, and clean and dry them with acetone and alcohol. Rivet the 7017 aluminum alloy ingot to cover both sides with 1050 aluminum sheets to obtain the 7017 aluminum alloy pre-clad plate. The specific riveting method is as follows: Drill holes on both sides of the sheet and rivet it with pure aluminum rivets to fix the four corners of the laminated composite plate together. The hole depth is 15mm, and the pure aluminum rivet length is 20mm.

[0048] Pre-rolling and thinning of the pre-clad sheet: The pre-clad sheet was held at 450℃ for 1.5 hours. During rolling, to prevent misalignment of the cladding sheet, the initial two passes had a reduction of 5%, and the remaining passes had a reduction of 20%–50%. Intermediate annealing was performed between passes at 460℃ for 20 minutes, but no intermediate annealing was performed before the last pass. A 5mm thick 7017 alloy pre-clad sheet was obtained.

[0049] Comparative Example 2

[0050] Fabrication of 5mm thick single 7055 aluminum alloy pre-clad plates

[0051] The mass percentage of the 7055 aluminum alloy ingot used is: Si≤0.01%, Fe≤0.05%, Cu=2.5%, Mn≤0.01%, Mg=2.2%, Cr=0.005%, Zn=8.2%, Ti=0.005%, Zr=0.131%, Sc=0.25%, with the balance being Al. The ingot dimensions are 175mm×150mm×46mm.

[0052] Milling and homogenization of ingots: A 2-4 mm thick surface layer is milled off the aluminum alloy ingot using a milling machine, and a 10 mm section is cut off from the bottom of the ingot and a 15 mm section is cut off from the casting port using a saw. The treated ingot is then placed in a pit furnace for homogenization treatment. The homogenization treatment regime is as follows: the furnace temperature is raised to 400℃, held for 8 hours, and then the furnace temperature is raised to 460℃ and held for 36 hours.

[0053] Surface treatment and riveting of the pre-clad plate: Prepare two 1050 aluminum alloy sheets, each 155mm × 155mm × 1mm in size. Grind the surfaces of the ingot and the sheets to create cross-scratches, then clean and dry them with acetone and alcohol. Rivet the 7055 aluminum alloy ingot to cover both sides with 1050 aluminum sheets, resulting in a 7055 aluminum alloy pre-clad plate. The specific riveting method is as follows: Drill holes on both sides of the sheet and rivet it with pure aluminum rivets to fix the four corners of the laminated composite plate together. The hole depth is 15mm, and the pure aluminum rivet length is 20mm.

[0054] Pre-rolling and thinning of the pre-clad sheet: The pre-clad sheet was held at 450℃ for 1.5 hours. During rolling, to prevent misalignment of the cladding sheet, the initial two passes had a reduction of 5%, and the remaining passes had a reduction of 20%–50%. Intermediate annealing was performed between passes at 460℃ for 20 minutes, but no intermediate annealing was performed before the last pass. A 5mm thick 7055 alloy pre-clad sheet was obtained.

[0055] Example 1

[0056] Prepare an aluminum / aluminum laminated composite plate with a thickness of 5 mm and a 7017 / 7055 thickness ratio of 1:4. (The stacking order is: 7055 / 7017 / 7017 / 7055 pre-clad plate)

[0057] The 7017 aluminum alloy ingots used have the following mass percentages: Si ≤ 0.01%, Fe ≤ 0.05%, Cu ≤ 0.01%, Mn = 0.28%, Mg = 2.9%, Cr = 0.12%, Ni ≤ 0.01%, Zn = 4.9%, Ti = 0.005%, Zr = 0.125%, Sc = 0.25%, with the balance being Al. The ingot dimensions are 175mm × 150mm × 46mm; the mass percentage of the 7055 aluminum alloy ingot used is: Si≤0.01%, Fe≤0.05%, Cu=2.5%, Mn≤0.01%, Mg=2.2%, Cr=0.005%, Zn=8.2%, Ti=0.005%, Zr=0.131%, Sc=0.25%, with the balance being Al, and the ingot size is 175mm×150mm×46mm.

[0058] Milling and homogenization of ingots: A 2-4 mm thick surface layer is milled off the aluminum alloy ingot using a milling machine, and a 10 mm section is cut off from the bottom of the ingot and a 15 mm section is cut off from the casting port using a saw. The treated ingot is then placed in a pit furnace for homogenization treatment. The homogenization treatment regime is as follows: the furnace temperature is raised to 400℃, held for 8 hours, and then the furnace temperature is raised to 460℃ and held for 36 hours.

[0059] Surface treatment and riveting of the pre-clad panels: Prepare four 155mm×155mm×1mm 1050 aluminum alloy sheets. Grind the surfaces of the ingots and sheets to create cross-scratches, and clean and dry them with acetone and alcohol. Rivet the sides of the 7017 and 7055 aluminum alloy ingots with 1050 aluminum sheets to obtain 7017 and 7055 aluminum alloy pre-clad panels. The specific riveting method is as follows: Drill holes on both sides of the sheet and rivet them with pure aluminum rivets to fix the four corners of the laminated composite panel together. The hole depth is 15mm, and the pure aluminum rivet length is 20mm.

[0060] Pre-rolling and thinning of the pre-clad sheet: The pre-clad sheet was held at 450℃ for 1.5 hours. During rolling, to prevent misalignment of the cladding sheet, the initial two passes had a reduction of 5%, and the remaining passes had a reduction of 20%–50%. Intermediate annealing was performed between passes at 460℃ for 20 minutes, but no intermediate annealing was performed before the last pass. This yielded a 3mm thick 7017 alloy pre-clad sheet and a 12mm thick 7055 alloy pre-clad sheet.

[0061] Surface treatment and riveting of the laminated composite panel: The 7017 alloy pre-clad panel is cut into sheets measuring 200mm × 155mm × 3mm, and the 7055 alloy pre-clad panel is cut into sheets measuring 200mm × 155mm × 12mm. The bonding surfaces of the two pre-clad panels are then roughened, cleaned, and dried using acetone and alcohol. The 7017 and 7055 pre-clad panels are stacked in sequence. Holes are drilled at both ends of the panels, and pure aluminum rivets are used to rivet them together, securing the four corners of the laminated composite panel. The holes penetrate both pre-clad panels, and the pure aluminum rivets are 22mm long.

[0062] Rolling of the laminated composite plate: The riveted laminated plate is stress-relieved annealed at 445℃ for 1.5 hours, with a reduction of 20% to 50% per pass and an intermediate annealing at 460℃ for 20 minutes between passes. An exception is made before the last pass, where no intermediate annealing is performed. After obtaining a 440mm × 156mm × 5mm thick laminated composite plate, it is cut in half along the transverse direction to obtain a laminated plate with a length × width × height of 220mm × 156mm × 5mm. Two laminated plates are stacked and riveted together, and the above rolling process is repeated. A cumulative composite rolling process is performed in one pass, with 7055 / 7017 laminated composite plates and 7017 / 7055 laminated composite plates stacked in that order, to obtain a 5mm thick laminated composite plate.

[0063] Heat treatment of laminated composite panels: The laminated composite panels are solution treated in a box furnace and then aged in a drying oven. The solution treatment regime involves heating the panels in the furnace until the furnace temperature reaches 470℃, holding at that temperature for 70 minutes, followed immediately by water quenching. The aging treatment regime involves heating the panels in the furnace until the temperature in the drying oven reaches 120℃, holding at that temperature for 24 hours, and then removing them to cool to room temperature.

[0064] Example 2

[0065] Prepare an aluminum / aluminum laminated composite plate with a thickness of 5 mm and a 7017 / 7055 thickness ratio of 1:4. (The stacking order is: 7055 / 7017 / 7055 / 7017 pre-clad plate)

[0066] The 7017 aluminum alloy ingots used have the following mass percentages: Si ≤ 0.01%, Fe ≤ 0.05%, Cu ≤ 0.01%, Mn = 0.28%, Mg = 2.9%, Cr = 0.12%, Ni ≤ 0.01%, Zn = 4.9%, Ti = 0.005%, Zr = 0.125%, Sc = 0.25%, with the balance being Al. The ingot dimensions are 175mm × 150mm × 46mm; the mass percentage of the 7055 aluminum alloy ingot used is: Si≤0.01%, Fe≤0.05%, Cu=2.5%, Mn≤0.01%, Mg=2.2%, Cr=0.005%, Zn=8.2%, Ti=0.005%, Zr=0.131%, Sc=0.25%, with the balance being Al, and the ingot size is 175mm×150mm×46mm.

[0067] Milling and homogenization of ingots: A 2-4 mm thick surface layer is milled off the aluminum alloy ingot using a milling machine, and a 10 mm section is cut off from the bottom of the ingot and a 15 mm section is cut off from the casting port using a saw. The treated ingot is then placed in a pit furnace for homogenization treatment. The homogenization treatment regime is as follows: the furnace temperature is raised to 400℃, held for 8 hours, and then the furnace temperature is raised to 460℃ and held for 36 hours.

[0068] Surface treatment and riveting of the pre-clad panels: Prepare four 155mm×155mm×1mm 1050 aluminum alloy sheets. Grind the surfaces of the ingots and sheets to create cross-scratches, and clean and dry them with acetone and alcohol. Rivet the sides of the 7017 and 7055 aluminum alloy ingots with 1050 aluminum sheets to obtain 7017 and 7055 aluminum alloy pre-clad panels. The specific riveting method is as follows: Drill holes on both sides of the sheet and rivet them with pure aluminum rivets to fix the four corners of the laminated composite panel together. The hole depth is 15mm, and the pure aluminum rivet length is 20mm.

[0069] Pre-rolling and thinning of the pre-clad sheet: The pre-clad sheet was held at 450℃ for 1.5 hours. During rolling, to prevent misalignment of the cladding sheet, the initial two passes had a reduction of 5%, and the remaining passes had a reduction of 20%–50%. Intermediate annealing was performed between passes at 460℃ for 20 minutes, but no intermediate annealing was performed before the last pass. This yielded a 3mm thick 7017 alloy pre-clad sheet and a 12mm thick 7055 alloy pre-clad sheet.

[0070] Surface treatment and riveting of the laminated composite panel: The 7017 alloy pre-clad panel is cut into sheets measuring 200mm × 155mm × 3mm, and the 7055 alloy pre-clad panel is cut into sheets measuring 200mm × 155mm × 12mm. The bonding surfaces of the two pre-clad panels are then roughened, cleaned, and dried using acetone and alcohol. The 7017 and 7055 pre-clad panels are stacked in sequence. Holes are drilled at both ends of the panels, and pure aluminum rivets are used to rivet them together, securing the four corners of the laminated composite panel. The holes penetrate both pre-clad panels, and the pure aluminum rivets are 22mm long.

[0071] Rolling of the laminated composite plate: The riveted laminated plate is stress-relieved annealed at 445℃ for 1.5 hours, with a reduction of 20% to 50% per pass and an intermediate annealing at 460℃ for 20 minutes between passes. An exception is made before the last pass, where no intermediate annealing is performed. After obtaining a 440mm × 156mm × 5mm thick laminated composite plate, it is cut in half along the transverse direction to obtain a laminated plate with a length × width × height of 220mm × 156mm × 5mm. Two laminated plates are stacked and riveted together, and the above rolling process is repeated. A cumulative composite rolling process is performed in the stacking sequence of 7055 / 7017 laminated composite plates to obtain a 5mm thick laminated composite plate.

[0072] Heat treatment of laminated composite panels: The laminated composite panels are solution treated in a box furnace and then aged in a drying oven. The solution treatment regime involves heating the panels in the furnace until the furnace temperature reaches 470℃, holding at that temperature for 70 minutes, followed immediately by water quenching. The aging treatment regime involves heating the panels in the furnace until the temperature in the drying oven reaches 120℃, holding at that temperature for 24 hours, and then removing them to cool to room temperature.

[0073] Example 3

[0074] Prepare an aluminum / aluminum laminated composite plate with a thickness of 5 mm and a 7017 / 7055 thickness ratio of 1:4. (The stacking order is: 7017 / 7055 / 7055 / 7017 pre-clad plate)

[0075] The 7017 aluminum alloy ingots used have the following mass percentages: Si ≤ 0.01%, Fe ≤ 0.05%, Cu ≤ 0.01%, Mn = 0.28%, Mg = 2.9%, Cr = 0.12%, Ni ≤ 0.01%, Zn = 4.9%, Ti = 0.005%, Zr = 0.125%, Sc = 0.25%, with the balance being Al. The ingot dimensions are 175mm × 150mm × 46mm; the mass percentage of the 7055 aluminum alloy ingot used is: Si≤0.01%, Fe≤0.05%, Cu=2.5%, Mn≤0.01%, Mg=2.2%, Cr=0.005%, Zn=8.2%, Ti=0.005%, Zr=0.131%, Sc=0.25%, with the balance being Al, and the ingot size is 175mm×150mm×46mm.

[0076] Milling and homogenization of ingots: A 2-4 mm thick surface layer is milled off the aluminum alloy ingot using a milling machine, and a 10 mm section is cut off from the bottom of the ingot and a 15 mm section is cut off from the casting port using a saw. The treated ingot is then placed in a pit furnace for homogenization treatment. The homogenization treatment regime is as follows: the furnace temperature is raised to 400℃, held for 8 hours, and then the furnace temperature is raised to 460℃ and held for 36 hours.

[0077] Surface treatment and riveting of the pre-clad panels: Prepare four 155mm×155mm×1mm 1050 aluminum alloy sheets. Grind the surfaces of the ingots and sheets to create cross-scratches, and clean and dry them with acetone and alcohol. Rivet the sides of the 7017 and 7055 aluminum alloy ingots with 1050 aluminum sheets to obtain 7017 and 7055 aluminum alloy pre-clad panels. The specific riveting method is as follows: Drill holes on both sides of the sheet and rivet them with pure aluminum rivets to fix the four corners of the laminated composite panel together. The hole depth is 15mm, and the pure aluminum rivet length is 20mm.

[0078] Pre-rolling and thinning of the pre-clad sheet: The pre-clad sheet was held at 450℃ for 1.5 hours. During rolling, to prevent misalignment of the cladding sheet, the initial two passes had a reduction of 5%, and the remaining passes had a reduction of 20%–50%. Intermediate annealing was performed between passes at 460℃ for 20 minutes, but no intermediate annealing was performed before the last pass. This yielded a 3mm thick 7017 alloy pre-clad sheet and a 12mm thick 7055 alloy pre-clad sheet.

[0079] Surface treatment and riveting of the laminated composite panel: The 7017 alloy pre-clad panel is cut into sheets measuring 200mm × 155mm × 3mm, and the 7055 alloy pre-clad panel is cut into sheets measuring 200mm × 155mm × 12mm. The bonding surfaces of the two pre-clad panels are then roughened, cleaned, and dried using acetone and alcohol. The 7017 and 7055 pre-clad panels are stacked in sequence. Holes are drilled at both ends of the panels, and pure aluminum rivets are used to rivet them together, securing the four corners of the laminated composite panel. The holes penetrate both pre-clad panels, and the pure aluminum rivets are 22mm long.

[0080] Rolling of the laminated composite plate: The riveted laminated plate is stress-relieved annealed at 445℃ for 1.5 hours, with a reduction of 20% to 50% per pass and an intermediate annealing at 460℃ for 20 minutes between passes. An exception is made before the last pass, where no intermediate annealing is performed. After obtaining a 440mm × 156mm × 5mm thick laminated composite plate, it is cut in half along the transverse direction to obtain a laminated plate with a length × width × height of 220mm × 156mm × 5mm. Two laminated plates are stacked and riveted together, and the above rolling process is repeated. A cumulative composite rolling process is performed in one pass, with 7017 / 7055 laminated composite plates stacked in sequence, to obtain a 5mm thick laminated composite plate.

[0081] Heat treatment of laminated composite panels: The laminated composite panels are solution treated in a box furnace and then aged in a drying oven. The solution treatment regime involves heating the panels in the furnace until the furnace temperature reaches 470℃, holding at that temperature for 70 minutes, followed immediately by water quenching. The aging treatment regime involves heating the panels in the furnace until the temperature in the drying oven reaches 120℃, holding at that temperature for 24 hours, and then removing them to cool to room temperature.

[0082] The following performance tests were performed on the products obtained in the examples:

[0083] The longitudinal tensile properties of the 7017 / 1050 / 7055 laminated composite board were tested according to the national standard GB / T 228.1-2010. The Vickers hardness of the 7017 and 7055 layers of the board was tested according to the national standard GB / T 231.1-2009. The bending properties of the 7017 / 1050 / 7055 laminated composite board were tested according to the national standard GB / T 232-2010. The Hopkinson bar test was conducted on the 7017 / 1050 / 7055 laminated composite board according to the national standard GB / T 34108-2017.

[0084] Table 1 Performance data of Comparative Examples 1-2 and Examples 1-3 of the present invention

[0085]

[0086]

[0087] Table 2. Experimental performance (true stress-strain curves) of Hopkinson compression bars in Comparative Examples 1-2 and Examples 1-2 of the present invention.

[0088]

[0089] Metallographic images of the aluminum / aluminum laminated composite plates prepared in Examples 1-3 of this invention are shown below. Figure 2 As shown, the stretching curves of Comparative Examples 1-2 and Examples 1-3 are as follows: Figure 3 As shown, the strength of the composite material is between that of 7055 and 7017, while the total elongation is increased by 30% compared to 7017.

[0090] Regarding impact strength, compared to single 7017 and 7055 aluminum alloy sheets, the laminated composite plate prepared by this invention exhibits a greater ability to absorb impact energy and improve its impact resistance when subjected to high-speed impact due to the mutual restraint between the 7055 alloy and the 7017 alloy.

Claims

1. A method for preparing a high-strength, high-ductility multilayer aluminum alloy plate, characterized in that, The aluminum alloy used is grade 7017, and its composition by weight percentage is: Si≤0.35%, Fe≤0.45%, Cu≤0.2%, 0.05%≤Mn≤0.50%, 2.0%≤Mg≤3.0%, Cr≤0.35%, Ni≤0.1%, 4.0%≤Zn≤5.2%, Ti≤0.15%, 0.10%≤Zr≤0.25%, Sc≤0.25%, with the balance being Al; The aluminum alloy used is grade 7055, and its composition by weight percentage is: Si≤0.1%, Fe≤0.15%, 2.0%≤Cu≤2.6%, Mn≤0.05%, 1.8%≤Mg≤2.3%, Cr≤0.04%, 7.6%≤Zn≤8.4%, Ti≤0.06%, 0.08%≤Zr≤0.25%, Sc≤0.25%, with the balance being Al; Follow these steps: (1) Preparation of the original ingot: Prepare 7017 aluminum alloy ingots and 7055 aluminum alloy ingots with the same area and thickness. Cut off the casting end and bottom of the ingots, and after milling the surface of the ingots, perform two-stage homogenization treatment on the two aluminum alloys. The first stage is heated to 400℃ in the furnace and held for 8 hours. The second stage is heated to 460℃ and held for 36 hours. (2) Preparation of pre-coated plates: Prepare four 1050 aluminum alloy thin plates with length and width larger than the ingot in step (1). After grinding, cleaning and drying the surfaces of the ingot and thin plates, stack them alternately in the order of 1050 aluminum alloy thin plates, ingot, and 1050 aluminum alloy thin plates. Then, use riveting to coat the sides of the 7017 and 7055 aluminum alloy ingots with 1050 aluminum plates to obtain 7017 and 7055 aluminum alloy pre-coated plates respectively. (3) Pre-rolling and thinning of pre-clad plates: 7017 and 7055 pre-clad plates are rolled and thinned respectively. In order to prevent the aluminum cladding plate from shifting during rolling, the initial two passes have a reduction of 5%, and the remaining passes have a reduction of 20%~50%. Stress relief annealing is performed before rolling at a temperature of 430℃~480℃ and a holding time of 1.5h. Intermediate annealing is performed between passes during rolling at a temperature of 440℃~475℃ and a duration of 20min. No intermediate annealing is performed before the last pass. After rolling and thinning, the thickness ratio of 7017 pre-clad plate to 7055 pre-clad plate is 1:1~1:

10. (4) Trimming of pre-coated plates: Trim the pre-coated plates that have been rolled and thinned, and select plates of appropriate size to avoid the rivet positions; (5) Surface cleaning of pre-coated panels: roughen, clean and dry the surfaces of the two types of pre-coated panels to remove surface stains; (6) Fixing treatment of laminated composite panels: After cleaning, the pre-composite panels are stacked in the order of 7017 pre-composite panels and 7055 pre-composite panels and then riveted to make the joint surfaces of the laminated composite panels contact and fix them. (7) Rolling thinning of laminated composite plate: The fixed laminated composite plate is rolled. Before rolling, stress relief annealing is performed at a temperature of 430℃~475℃ and held for 1.5h. The reduction of each pass during rolling is 20%~50%. Intermediate annealing is performed between two passes at a temperature of 420℃~470℃ for 20min. No intermediate annealing is performed before the last pass to obtain a preliminarily bonded 7017 / 1050 / 7055 laminated composite plate. (8) Preparation of laminated composite board: Cut the obtained laminated composite board in half along the transverse direction of the board, and repeat the operations of steps (5), (6), and (7) to carry out composite cumulative rolling; (9) Heat treatment regime of laminated composite plate: The laminated composite plate is heated in a box furnace. After the furnace temperature rises to 470℃, it is kept at the temperature for 70 minutes for solution treatment, and then immediately water quenched; the laminated composite plate is aged in a drying oven.

2. The method for preparing a high-strength, high-ductility multilayer aluminum alloy plate according to claim 1, characterized in that, In step (2), when riveting, 1050 aluminum alloy sheet, ingot, and 1050 aluminum alloy sheet are stacked alternately in sequence. After the sheets are stacked alternately, holes are drilled on both sides of the sheet and riveted with pure aluminum rivets to fix the four corners together. The hole depth is 15mm and the length of the pure aluminum rivet is 20mm.

3. The method for preparing a high-strength, high-ductility multilayer aluminum alloy plate according to claim 1, characterized in that, The aging process for step (9) is as follows: after the laminated composite board is heated to 120°C in the furnace, it is kept at that temperature for 24 hours, and then cooled to room temperature after being removed.

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