Aluminum alloy plate high-temperature rolling rapid connection method

Abstract

The invention discloses an aluminum alloy plate high-temperature rolling rapid connection method, and belongs to the field of aluminum alloy diffusion connection. The invention aims to solve the problems of low production efficiency and low strength caused by high connection temperature, long heat preservation time, difficulty in breaking an oxide film and high equipment requirement during large-area connection in the existing aluminum alloy connection process. On the basis of a plate hot-rolling composite process, an interlayer foil is added between to-be-connected areas of an aluminum alloy plate, during rolling at the temperature lower than or close to the eutectic temperature of the interlayer material and aluminum, an interface original oxidation film is broken through plastic deformation, the temperature of a connecting interface is increased to reach the reaction temperature, and the interlayer material is rapidly diffused; and efficient metallurgical connection of the aluminum alloy plates is achieved. According to the method, interface vacuum protection can be achieved in the rolling connection process, the problem that materials are violently oxidized in the non-vacuum high-temperature environment is effectively avoided, meanwhile, the equipment requirement is low during large-area connection, and cost can be greatly reduced and efficiency can be greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy diffusion bonding, and specifically relates to a method for rapid bonding of aluminum alloy sheets by high-temperature rolling. Background Technology

[0002] Today's industrial civilization is in a phase of rapid development, placing increasingly higher demands on the structural and functional requirements of mechanical equipment components. Simultaneously, reducing energy consumption is a global hot topic, and lightweight construction is emerging in various industries, including aerospace, energy, and transportation. The most direct solution to the problem of lightweight components is to use lightweight materials to fabricate lightweight structural components. Aluminum, as the most abundant metallic element in the Earth's crust, has a density of only 2.7 g / cm³. 3 Aluminum, at one-third the weight of steel, can significantly reduce the weight of components. Pure aluminum has good ductility but low strength, making it difficult to use directly as a structural material; aluminum alloys have higher strength but generally poorer ductility, which limits their use in manufacturing complex components. At the same time, aluminum is highly reactive, forming dense oxides in air, making its weldability far lower than that of steel.

[0003] Currently, the widespread application of lightweight aluminum alloys in fields such as machinery and aerospace has become an urgent need, and high-quality connections are a prerequisite for their effective application in engineering. Traditional aluminum alloy connection methods mainly include bonding, mechanical connection, and welding. Welding, as the most widely used process that meets the advanced requirements of lightweighting and reliability, has attracted much attention. It mainly involves various methods in the field of welding, such as fusion welding, brazing, and pressure welding. Commonly used connection methods include diffusion welding, laser welding, friction stir welding, and brazing. Aluminum alloy diffusion connection performance is relatively low. Due to the obstruction of the oxide film, it usually requires higher temperature, pressure, and longer holding time, resulting in low efficiency and generally poor performance. Laser welding of aluminum alloys is prone to porosity, cracks, and elemental segregation. At the same time, aluminum alloys are high-reflectivity materials, resulting in low processing stability. Friction stir welding, as a newly developed solid-state welding technology in recent years, breaks down the original grains during connection. Although the microstructure can be refined, a large amount of distortion will occur inside the grains. In addition, the process is not mature when performing large-area connections. Brazing is costly and has generally poor connection strength. There is an urgent need for a large-area joining method that is simple in process, low in cost, highly efficient, and compatible with aluminum alloy hot forming technology. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of high connection temperature, long heat preservation time, difficulty in breaking the oxide film, and high equipment requirements in the existing aluminum alloy connection process, which result in low production efficiency and low strength. The invention provides a method for rapid connection of aluminum alloy sheets by high-temperature rolling.

[0005] A method for rapid connection of aluminum alloy sheets by high-temperature rolling is specifically completed according to the following steps:

[0006] I. Blank processing:

[0007] Cut aluminum alloy sheets to the appropriate size according to actual processing needs, then grind the sheets flat, clean and dry them to obtain the processed aluminum alloy sheets.

[0008] II. Applying a release agent:

[0009] Apply peelable adhesive to the surface of the joint area of ​​the treated aluminum alloy sheet, and then spray release agent on the surface of the non-joint area. After spraying, peel off the peelable adhesive. If the treated aluminum alloy sheet is fully joined, there is no need to apply peelable adhesive or spray release agent.

[0010] 3. Trim the middle layer:

[0011] Take the intermediate layer material and cut it to the same size as the connecting area of ​​the aluminum alloy plate to obtain the cut intermediate layer material.

[0012] IV. Blank Assembly:

[0013] Place the cut intermediate layer material in the connection area between the two aluminum alloy plates obtained in step two to form a "sandwich" structure blank of aluminum alloy plate-intermediate layer material-aluminum alloy plate.

[0014] V. Welding and sealing:

[0015] The "sandwich" structure blank of aluminum alloy plate-intermediate layer material-aluminum alloy plate is sealed and welded around its perimeter, and an opening is reserved for welding an air pipe with a valve. This allows the surfaces to be connected to the air pipe while being isolated from the outside, forming a sealed cavity, and thus obtaining the sealed aluminum alloy plate assembly.

[0016] VI. Apply protective agent:

[0017] A release agent is sprayed onto the outer surface of the sealed aluminum alloy plate assembly to prevent the aluminum alloy plate from sticking to the rolls during rolling, resulting in an aluminum alloy plate assembly with the release agent sprayed onto the outer surface.

[0018] VII. Vacuuming:

[0019] Connect the air pipe on the aluminum alloy plate assembly after the outer surface is coated with a release agent to a vacuum pump, and then evacuate the connection interface to obtain the aluminum alloy plate assembly after evacuation.

[0020] 8. High-temperature rolling:

[0021] After the vacuum is removed, the aluminum alloy plate assembly is placed in a heating furnace. After it is heated to the process temperature, it is sent to a rolling mill for high-temperature rapid rolling and connection. After cooling, the connected plate is obtained.

[0022] IX. Post-processing:

[0023] After cutting off the four sides of the connecting process area of ​​the plate after connection, the target connecting plate is obtained, thus completing the high-temperature rolling rapid connection method of aluminum alloy plates.

[0024] The principle of this invention:

[0025] Due to the extremely high stability of aluminum oxide films, interfacial bonding is difficult to achieve without an external energy field. Therefore, this invention proposes a high-temperature rolling rapid bonding technology for aluminum alloys. This technology utilizes a high-temperature rolling method for metallic materials, increasing the eutectic reaction between the intermediate layer and the plate. Diffusion bonding between the aluminum alloy sheet and the intermediate layer material can be achieved without the assistance of an external energy field (ultrasonic vibration, pulsed current, etc.). High-temperature rolling reaction diffusion bonding refers to applying sufficient pressure through rolls at a certain temperature to induce plastic deformation in two or more sheets of the same or different materials to be bonded. This results in a tight bond between the intermediate layer material and the sheet interface, leading to reaction diffusion and a reliable metallurgical bond. Because this technology is simple to operate, low in cost, high in efficiency, can achieve ideal mechanical properties, can bond different grades of the same material, and incorporates multiple bonding mechanisms such as mechanical riveting and diffusion bonding at the microscopic level, it can effectively solve some of the problems associated with diffusion bonding of aluminum alloys under appropriate process parameters.

[0026] The present invention has the following beneficial effects:

[0027] (1) The present invention uses a rolling method to apply force to the plate. Compared with the traditional static pressure diffusion, the required equipment tonnage is small and the connection speed is fast, which has the effect of reducing costs and increasing efficiency.

[0028] (2) The present invention achieves rapid diffusion by the intermediate layer material undergoing a eutectic reaction with the aluminum alloy sheet at high temperature. At the same time, the pre-sealing and vacuuming method is used to prevent interface oxidation. During rolling, the aluminum alloy oxide film can be broken and the intermediate layer material can be completely diffused instantly, which significantly reduces the process parameters such as temperature and time required for traditional static pressure diffusion.

[0029] (3) The high-temperature rolling connection method used in this invention will cause certain plastic deformation of aluminum alloy, resulting in dynamic recrystallization, which will refine and homogenize the structure to a certain extent. During rolling, a large amount of plastic deformation work is converted into internal energy and heat is released during diffusion. The temperature of the connection interface increases significantly. The rolling temperature can be lower than the reaction temperature between the intermediate layer material and the aluminum alloy, thereby ensuring the mechanical properties of the plate.

[0030] (4) The present invention has excellent effect on connecting double-layer and multi-layer aluminum alloy plates with large area or complex geometric shape, and provides a method for rapid connection of thick plates. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the assembly of the sandwich structure blank in Example 1;

[0032] Figure 2 This is a schematic diagram of rapid diffusion bonding during high-temperature rolling in Example 1;

[0033] Figure 3 This is a SEM image of the microstructure at the weld after Cu foil intermediate layer rolling and connection in Example 1.

[0034] Figure 4 This is a bar chart comparing the mechanical properties of aluminum alloy sheets before and after Cu foil interlayer rolling connection in Example 1;

[0035] Figure 5 This is a schematic diagram of the placement of the intermediate layer material and the spraying of the release agent in the rolling section of Example 2;

[0036] Figure 6 BSE image of the microstructure at the weld after the Zn foil interlayer is rolled and connected in Example 2;

[0037] Figure 7 The bar chart in Example 2 shows a comparison of the mechanical properties of aluminum alloy sheets before and after the Zn foil interlayer was rolled and connected.

[0038] Figure 8 For Comparative Example 1, the microstructure of the weld seam after high-temperature rolling connection without intermediate layer is shown in the optical microscope image.

[0039] Figure 9 For Comparative Example 2, the microstructure of the weld seam after ultra-high temperature rolling connection without intermediate layer is shown in the optical microscope image.

[0040] Figure 10 For Comparative Example 3, the microstructure of the weld seam after high-temperature rolling of the pure Al foil interlayer is shown in the optical microscope image.

[0041] Figure 11 Digital image of the sample after room temperature rolling and bonding of Cu foil interlayer for Comparative Example 4;

[0042] Figure 12 For Comparative Example 5, SEM images of the microstructure at the weld after hydrostatic vacuum diffusion bonding of Cu foil interlayer were used.

[0043] Figure 13 Comparison of room temperature mechanical properties of the weld seam after rolling connection of the original 5A06 aluminum alloy sheet, Example 1 and Comparative Examples 1-5;

[0044] In the diagram, 1-pure aluminum capillary, 2-upper aluminum alloy sheet, 3-intermediate layer material, 4-lower aluminum alloy sheet, 5-high temperature heating furnace, and 6-roll. Detailed Implementation

[0045] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0046] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. The materials, reagents, and methods used, unless otherwise specified, are all conventional materials, reagents, and methods in the art, and can be obtained commercially by those skilled in the art.

[0047] Specific Implementation Method 1: This implementation method describes a rapid connection method for high-temperature rolling of aluminum alloy sheets, which is specifically completed according to the following steps:

[0048] I. Blank processing:

[0049] Cut aluminum alloy sheets to the appropriate size according to actual processing needs, then grind the sheets flat, clean and dry them to obtain the processed aluminum alloy sheets.

[0050] II. Applying a release agent:

[0051] Apply peelable adhesive to the surface of the joint area of ​​the treated aluminum alloy sheet, and then spray release agent on the surface of the non-joint area. After spraying, peel off the peelable adhesive. If the treated aluminum alloy sheet is fully joined, there is no need to apply peelable adhesive or spray release agent.

[0052] 3. Trim the middle layer:

[0053] Take the intermediate layer material and cut it to the same size as the connecting area of ​​the aluminum alloy plate to obtain the cut intermediate layer material.

[0054] IV. Blank Assembly:

[0055] Place the cut intermediate layer material in the connection area between the two aluminum alloy plates obtained in step two to form a "sandwich" structure blank of aluminum alloy plate-intermediate layer material-aluminum alloy plate.

[0056] V. Welding and sealing:

[0057] The "sandwich" structure blank of aluminum alloy plate-intermediate layer material-aluminum alloy plate is sealed and welded around its perimeter, and an opening is reserved for welding an air pipe with a valve. This allows the surfaces to be connected to the air pipe while being isolated from the outside, forming a sealed cavity, and thus obtaining the sealed aluminum alloy plate assembly.

[0058] VI. Apply protective agent:

[0059] A release agent is sprayed onto the outer surface of the sealed aluminum alloy plate assembly to prevent the aluminum alloy plate from sticking to the rolls during rolling, resulting in an aluminum alloy plate assembly with the release agent sprayed onto the outer surface.

[0060] VII. Vacuuming:

[0061] Connect the air pipe on the aluminum alloy plate assembly after the outer surface is coated with a release agent to a vacuum pump, and then evacuate the connection interface to obtain the aluminum alloy plate assembly after evacuation.

[0062] 8. High-temperature rolling:

[0063] After the vacuum is removed, the aluminum alloy plate assembly is placed in a heating furnace. After it is heated to the process temperature, it is sent to a rolling mill for high-temperature rapid rolling and connection. After cooling, the connected plate is obtained.

[0064] IX. Post-processing:

[0065] After cutting off the four sides of the connecting process area of ​​the plate after connection, the target connecting plate is obtained, thus completing the high-temperature rolling rapid connection method of aluminum alloy plates.

[0066] This embodiment is based on a hot-rolled composite process for aluminum alloy sheets. An intermediate foil layer is added between the areas to be joined in the aluminum alloy sheets. During rolling at temperatures below or near the eutectic temperature of the intermediate foil and aluminum, plastic deformation causes the original oxide film at the interface to rupture, raising the interface temperature to the reaction temperature. The intermediate foil then diffuses rapidly, achieving efficient metallurgical joining of the aluminum alloy sheets. The method provided by this invention can achieve interface vacuum protection during the rolling joining process, effectively avoiding the problem of severe oxidation of materials under non-vacuum high-temperature environments. Furthermore, it requires less equipment for large-area joining, significantly reducing costs and increasing efficiency.

[0067] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the width of the peelable adhesive mentioned in step two is 5mm~10mm. The other steps are the same as in Specific Implementation Method One.

[0068] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the isolating agent mentioned in step two is boron nitride. The other steps are the same as in Specific Implementation Method One or Two.

[0069] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the separating agent mentioned in step six is ​​boron nitride. The other steps are the same as in Specific Implementation Methods One to Three.

[0070] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: in step seven, a vacuum is drawn at the connection interface until the vacuum level is below 100 Pa. The other steps are the same as in Specific Implementation Methods One to Four.

[0071] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the intermediate layer material mentioned in step three is copper foil, nickel foil, zinc sheet, or silver foil; the thickness of the intermediate layer material is 5μm to 50μm. The other steps are the same as in Specific Implementation Methods One to Five.

[0072] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: when the intermediate layer material is copper foil, the rolling temperature in step eight is 510℃~570℃, the rolling reduction is 5%~50%, and the instantaneous temperature at the connection interface should reach or exceed 548℃. Other steps are the same as in Specific Implementation Methods One to Six.

[0073] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: when the intermediate layer material is nickel foil, the rolling temperature in step eight is 580℃~640℃, the rolling reduction is 5%~50%, and the instantaneous temperature at the connection interface should reach or exceed 640℃. Other steps are the same as in Specific Implementation Methods One to Seven.

[0074] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: when the intermediate layer material is zinc sheet, the rolling temperature in step eight is 350℃~420℃, the rolling reduction is 5%~50%, and the instantaneous temperature at the connection interface should reach or exceed 380℃. Other steps are the same as in Specific Implementation Methods One to Eight.

[0075] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: when the intermediate layer material is silver foil, the rolling temperature in step eight is 520℃~580℃, the rolling reduction is 5%~50%, and the instantaneous temperature at the connection interface should reach or exceed 566℃. Other steps are the same as in Specific Implementation Methods One to Nine.

[0076] The beneficial effects of the present invention are verified using the following embodiments:

[0077] Example 1: A method for rapid connection of aluminum alloy sheets by high-temperature rolling, specifically completed according to the following steps:

[0078] I. Blank processing:

[0079] Cut aluminum alloy sheets to the appropriate size according to actual processing needs, then grind the sheets flat. During the grinding stage, ensure that the sheets are smooth and without obvious deformation. Then clean with anhydrous ethanol to remove surface contaminants, blow dry, and obtain the processed aluminum alloy sheet.

[0080] The aluminum alloy sheet mentioned in step one is 5A06 aluminum alloy with a thickness of 2mm;

[0081] II. Cutting the middle layer:

[0082] Take the intermediate layer material and cut it to the same size as the connecting area of ​​the aluminum alloy plate. During the cutting process, ensure that the intermediate layer material is free of contamination and wrinkles to obtain the cut intermediate layer material.

[0083] The intermediate layer material mentioned in step two is copper foil with a thickness of 10 μm;

[0084] III. Blank Assembly:

[0085] Place the cut interlayer material into the connecting area between the two aluminum alloy plates obtained in step one, forming a "sandwich" structure blank of aluminum alloy plate-interlayer material-aluminum alloy plate. The assembled structure is as follows: Figure 1 As shown;

[0086] IV. Welding and sealing:

[0087] The "sandwich" structure blank of aluminum alloy plate-intermediate layer material-aluminum alloy plate is sealed and welded around its perimeter. A small opening is left at one end, and a pure aluminum capillary tube with a diameter of Φ6 is welded. The welding process ensures that the weld seam is completely sealed, and the joint surface can only be connected to the outside through the capillary tube to obtain the sealed aluminum alloy plate assembly.

[0088] V. Apply protective agent:

[0089] Boron nitride protective agent is sprayed onto the outer surface of the sealed aluminum alloy plate assembly to prevent the aluminum alloy plate from sticking to the rolls during rolling, resulting in an aluminum alloy plate assembly with an outer surface coated with a release agent.

[0090] VI. Vacuuming:

[0091] Connect the air pipe on the aluminum alloy plate assembly after the outer surface is coated with a release agent to a vacuum pump, and then evacuate the connection interface to 1 Pa to obtain the aluminum alloy plate assembly after evacuation.

[0092] VII. High-temperature rolling:

[0093] After the vacuum is removed, the aluminum alloy plate assembly is placed in a heating furnace and held at 520℃ for 30 minutes. Then, it is quickly taken out and placed into a rolling mill and rolled at a speed of 200 mm / s with a rolling reduction of 20%. After the rolling connection is completed, the rolling mill is turned off, and the connected aluminum alloy plate is taken out after air cooling.

[0094] VIII. Post-processing:

[0095] The connecting process area around the plate is removed to obtain the target connecting plate, thus completing the high-temperature rolling rapid connection method for aluminum alloy plates.

[0096] The schematic diagram of the blank assembly structure in step three of Example 1 is shown below. Figure 1 As shown; the schematic diagram of the high-temperature rolling rapid connection in step seven is as follows. Figure 2 As shown;

[0097] The microstructure of the weld seam of the aluminum alloy sheet after rolling and joining in step seven of Example 1 is as follows: Figure 3 As shown;

[0098] from Figure 3 As can be seen, the intermediate layer material diffuses completely along the grain boundaries, forming a diffusion zone with a width exceeding 1 mm at the weld. To characterize the weld strength, shear tests and composite tensile tests were used to perform room temperature mechanical property tests on the diffusion interface. The obtained weld shear strength and overall tensile strength of the welded plate are shown in Table 1 and Table 2. Figure 4 As shown, the strength of the weld after high-temperature rolling can reach 97% of the matrix. Due to the precipitation of a large number of reinforcing phases at the grain boundaries after diffusion, the overall tensile strength increases to 106% of the original plate, while the elongation decreases slightly.

[0099] Table 1

[0100]

[0101] Example 2: A method for rapid connection of aluminum alloy sheets by high-temperature rolling, specifically completed according to the following steps:

[0102] I. Blank processing:

[0103] Cut aluminum alloy sheets to the appropriate size according to actual processing needs, then grind the sheets flat. During the grinding stage, ensure that the sheets are smooth and without obvious deformation. Then clean with anhydrous ethanol to remove surface contaminants, blow dry, and obtain the processed aluminum alloy sheet.

[0104] The aluminum alloy sheet mentioned in step one is a 2A12 aluminum alloy sheet with a thickness of 4mm;

[0105] II. Applying a release agent:

[0106] Apply peelable adhesive to the surface of the connection area of ​​the treated aluminum alloy plate, and then spray release agent on the surface of the non-connection area. After spraying, peel off the peelable adhesive.

[0107] The separating agent mentioned in step two is boron nitride;

[0108] 3. Trim the middle layer:

[0109] Take the intermediate layer material and cut it to the same size as the connecting area of ​​the aluminum alloy plate. During the cutting process, ensure that the intermediate layer material is free of contamination and wrinkles to obtain the cut intermediate layer material.

[0110] The intermediate layer material mentioned in step three is a Zn foil; the thickness of the intermediate layer material is 20 μm.

[0111] IV. Blank Assembly:

[0112] Place the cut intermediate layer material in the connection area between the two aluminum alloy plates obtained in step two to form a "sandwich" structure blank of aluminum alloy plate-intermediate layer material-aluminum alloy plate.

[0113] V. Welding and sealing:

[0114] The "sandwich" structure blank of aluminum alloy plate-intermediate layer material-aluminum alloy plate is sealed and welded around its perimeter. A small opening is left at one end, and a pure aluminum capillary tube with a diameter of Φ6 is welded. The welding process ensures that the weld seam is completely sealed, and the joint surface can only be connected to the outside through the capillary tube to obtain the sealed aluminum alloy plate assembly.

[0115] VI. Apply protective agent:

[0116] Boron nitride protective agent is sprayed onto the outer surface of the sealed aluminum alloy plate assembly to prevent the aluminum alloy plate from sticking to the rolls during rolling, resulting in an aluminum alloy plate assembly with an outer surface coated with a release agent.

[0117] VII. Vacuuming:

[0118] Connect the air pipe on the aluminum alloy plate assembly after the outer surface is coated with a release agent to a vacuum pump, and then evacuate the connection interface to 1 Pa to obtain the aluminum alloy plate assembly after evacuation.

[0119] 8. High-temperature rolling:

[0120] After the vacuum is removed, the aluminum alloy plate assembly is placed in a heating furnace and heated to 430℃ for 20 minutes. Then, it is quickly taken out and placed into a rolling mill and rolled at a speed of 200 mm / s with a rolling reduction of 5%. After the rolling connection is completed, the rolling mill is turned off, and the connected aluminum alloy plate is taken out after air cooling.

[0121] IX. Post-processing:

[0122] After cutting off the four sides of the connecting process area of ​​the plate after connection, the target connecting plate is obtained, thus completing the high-temperature rolling rapid connection method of aluminum alloy plates.

[0123] In Example 2, step two, a schematic diagram of the area where the release agent is sprayed (non-connection area) and the area where the zinc sheet is laid (connection area) is shown below. Figure 5 As shown.

[0124] The microstructure of the weld seam of the rolled aluminum alloy sheet in Example 2 is as follows: Figure 6 As shown in the figure, the intermediate layer material diffuses completely along the grain boundaries, achieving complete metallurgical bonding. To characterize the weld bond strength, shear tests and composite tensile tests were used to test the room temperature mechanical properties of the diffusion interface. The obtained weld shear strength, post-weld plate shear strength, and overall tensile strength are shown in Table 2 and [Table data missing]. Figure 7As shown, the strength of the weld after high-temperature rolling can reach 98% of the matrix. However, due to the precipitation of a large number of hard and brittle reinforcing phases at the grain boundaries after diffusion, the overall tensile strength decreases to 93% of the original plate, and the elongation also decreases.

[0125] Table 2

[0126]

[0127] Comparative Example 1: This comparative example differs from Example 1 in that the 5A06 aluminum alloy is rolled together at the same temperature without an intermediate layer. That is, during high-temperature vacuum rolling, there is no intermediate layer material between the connecting surfaces. Specifically, this is accomplished according to the following steps:

[0128] I. Blank processing:

[0129] Cut aluminum alloy sheets to the appropriate size according to actual processing needs, then grind the sheets flat. During the grinding stage, ensure that the sheets are smooth and without obvious deformation. Then clean with anhydrous ethanol to remove surface contaminants, blow dry, and obtain the processed aluminum alloy sheet.

[0130] The aluminum alloy sheet mentioned in step one is 5A06 aluminum alloy with a thickness of 2mm;

[0131] 2. Stack the two processed aluminum alloy plates together, ensuring that the surfaces to be joined overlap. Then, use argon arc welding to seal the edges of the assembled blank. Leave a small opening at one end and weld a pure aluminum capillary tube with a diameter of Φ6mm. During the welding process, ensure that the weld seam is completely sealed, and the surfaces to be joined can only be connected to the outside through the capillary tube.

[0132] III. Applying Protective Agent:

[0133] Boron nitride protective agent is sprayed onto the outer surface of the sealed aluminum alloy plate assembly to prevent the aluminum alloy plate from sticking to the rolls during rolling, resulting in an aluminum alloy plate assembly with an outer surface coated with a release agent.

[0134] IV. Vacuuming:

[0135] Connect the air pipe on the aluminum alloy plate assembly after the outer surface is coated with a release agent to a vacuum pump, and then evacuate the connection interface to 1 Pa to obtain the aluminum alloy plate assembly after evacuation.

[0136] V. High-temperature rolling:

[0137] After the vacuum is removed, the aluminum alloy plate assembly is placed in a heating furnace and held at 520℃ for 30 minutes. Then, it is quickly taken out and placed into a rolling mill and rolled at a speed of 200 mm / s with a rolling reduction of 20%. After the rolling connection is completed, the rolling mill is turned off, and the connected aluminum alloy plate is taken out after air cooling.

[0138] VI. Post-processing:

[0139] The connecting process area around the plate is removed to obtain the target connecting plate, thus completing the high-temperature rolling rapid connection method for aluminum alloy plates.

[0140] Comparative Example 1: Aluminum alloy sheet joint interface after high-temperature vacuum rolling without intermediate layer, as shown in Figure 1. Figure 8 As shown in the figure. After rolling, the weld is very fine, indicating that the plate interface has achieved tight contact. After anodic coating, the original weld interface still exists, the grain boundaries have not broken through the interface oxide film, and there is no obvious diffusion. At this point, the connection is mainly achieved through mechanical riveting. To characterize the weld bonding strength, a shear test was used to perform room temperature mechanical property testing on the diffused interface. The obtained weld shear strength is shown in the figure. Figure 13 As shown. The shear strength is approximately 120 MPa, and the connection strength is low, only 47% of the matrix strength. Furthermore, since the connection is mechanical, it is considered unreliable for high-temperature applications.

[0141] Comparative Example 2: This comparative example differs from Example 1 in that the 5A06 aluminum alloy is rolled and connected at ultra-high temperature without an intermediate layer. Specifically, it is completed according to the following steps:

[0142] I. Blank processing:

[0143] Cut aluminum alloy sheets to the appropriate size according to actual processing needs, then grind the sheets flat. During the grinding stage, ensure that the sheets are smooth and without obvious deformation. Then clean with anhydrous ethanol to remove surface contaminants, blow dry, and obtain the processed aluminum alloy sheet.

[0144] The aluminum alloy sheet mentioned in step one is 5A06 aluminum alloy with a thickness of 2mm;

[0145] 2. Stack the two processed aluminum alloy plates together, ensuring that the surfaces to be joined overlap. Then, use argon arc welding to seal the edges of the assembled blank. Leave a small opening at one end and weld a pure aluminum capillary tube with a diameter of Φ6mm. During the welding process, ensure that the weld seam is completely sealed, and the surfaces to be joined can only be connected to the outside through the capillary tube.

[0146] III. Applying Protective Agent:

[0147] Boron nitride protective agent is sprayed onto the outer surface of the sealed aluminum alloy plate assembly to prevent the aluminum alloy plate from sticking to the rolls during rolling, resulting in an aluminum alloy plate assembly with an outer surface coated with a release agent.

[0148] IV. Vacuuming:

[0149] Connect the air pipe on the aluminum alloy plate assembly after the outer surface is coated with a release agent to a vacuum pump, and then evacuate the connection interface to 1 Pa to obtain the aluminum alloy plate assembly after evacuation.

[0150] V. High-temperature rolling:

[0151] After the vacuum is removed, the aluminum alloy plate assembly is placed in a heating furnace and held at 600℃ for 30 minutes. Then, it is quickly taken out and placed into a rolling mill and rolled at a speed of 200 mm / s with a rolling reduction of 30%. At this time, the joining temperature is close to the melting point of the plate (620.28℃). After the rolling and joining are completed, the rolling mill is turned off, and the joined aluminum alloy plate is taken out after air cooling.

[0152] VI. Post-processing:

[0153] The connecting process area around the plate is removed to obtain the target connecting plate, thus completing the high-temperature rolling rapid connection method for aluminum alloy plates.

[0154] Comparative Example 2: Aluminum composite sheet with no intermediate layer, after ultra-high temperature vacuum rolling, has the following connection interface: Figure 9 As shown, the grains are spherical and cast with obvious coarsening, indicating that the aluminum alloy is semi-solid at this temperature. At this point, the weld seam is still visible, and the connection is not a reliable metallurgical joint. Since the plate has completely failed at this point, the connection strength cannot be measured.

[0155] Comparative Example 3: This comparative example differs from Example 1 in that the intermediate layer material is a 0.5 mm thick high-purity Al sheet, the rolling temperature is 550°C, and the rolling reduction is 30%. Specifically, it was completed according to the following steps:

[0156] I. Blank processing:

[0157] Cut aluminum alloy sheets to the appropriate size according to actual processing needs, then grind the sheets flat. During the grinding stage, ensure that the sheets are smooth and without obvious deformation. Then clean with anhydrous ethanol to remove surface contaminants, blow dry, and obtain the processed aluminum alloy sheet.

[0158] The aluminum alloy sheet mentioned in step one is 5A06 aluminum alloy with a thickness of 2mm;

[0159] II. Cutting the middle layer:

[0160] Take the intermediate layer material and cut it to the same size as the connecting area of ​​the aluminum alloy plate. During the cutting process, ensure that the intermediate layer material is free of contamination and wrinkles to obtain the cut intermediate layer material.

[0161] The intermediate layer material mentioned in step two is high-purity Al foil with a thickness of 0.5 mm;

[0162] III. Blank Assembly:

[0163] Place the cut interlayer material into the connecting area between the two aluminum alloy plates obtained in step two, forming a "sandwich" structure blank of aluminum alloy plate-interlayer material-aluminum alloy plate. The assembled structure is as follows: Figure 1 As shown;

[0164] IV. Welding and sealing:

[0165] The "sandwich" structure blank of aluminum alloy plate-intermediate layer material-aluminum alloy plate is sealed and welded around its perimeter. A small opening is left at one end, and a pure aluminum capillary tube with a diameter of Φ6 is welded. The welding process ensures that the weld seam is completely sealed, and the joint surface can only be connected to the outside through the capillary tube to obtain the sealed aluminum alloy plate assembly.

[0166] V. Apply protective agent:

[0167] Boron nitride protective agent is sprayed onto the outer surface of the sealed aluminum alloy plate assembly to prevent the aluminum alloy plate from sticking to the rolls during rolling, resulting in an aluminum alloy plate assembly with an outer surface coated with a release agent.

[0168] VI. Vacuuming:

[0169] Connect the air pipe on the aluminum alloy plate assembly after the outer surface is coated with a release agent to a vacuum pump, and then evacuate the connection interface to 1 Pa to obtain the aluminum alloy plate assembly after evacuation.

[0170] VII. High-temperature rolling:

[0171] After the vacuum is removed, the aluminum alloy plate assembly is placed in a heating furnace and held at 550℃ for 30 minutes. Then, it is quickly taken out and placed into a rolling mill and rolled at a speed of 200 mm / s with a rolling reduction of 30%. After the rolling connection is completed, the rolling mill is turned off, and the connected aluminum alloy plate is taken out after air cooling.

[0172] VIII. Post-processing:

[0173] The connecting process area around the plate is removed to obtain the target connecting plate, thus completing the high-temperature rolling rapid connection method for aluminum alloy plates.

[0174] The aluminum alloy sheet connection interface obtained in Comparative Example 3 is as follows: Figure 10 As shown in the figure, the interfacial interlocking degree significantly increases after the addition of the interlayer. However, due to the low chemical potential gradient between the 5A06 aluminum alloy and the pure Al interlayer material, and the extremely high rolling rate, the diffusion motive force and diffusion time are insufficient, resulting in no significant diffusion phenomenon. To characterize the weld bond strength, a shear test was used to perform room temperature mechanical property testing on the diffusion-treated interface. The obtained weld shear strength is shown in the figure. Figure 13 As shown, the shear failure location is in the intermediate layer material, with a shear strength of approximately 100 MPa. The connection strength is low, only 40% of the matrix strength. Furthermore, since the connection is mechanical, it is considered unreliable for high-temperature applications.

[0175] Comparative Example 4: This comparative example differs from Example 1 in that the rolling connection temperature is room temperature, and the outer surface of the welded plate blank does not require spraying with boron nitride protective agent. Specifically, it is completed according to the following steps:

[0176] I. Blank processing:

[0177] Cut aluminum alloy sheets to the appropriate size according to actual processing needs, then grind the sheets flat. During the grinding stage, ensure that the sheets are smooth and without obvious deformation. Then clean with anhydrous ethanol to remove surface contaminants, blow dry, and obtain the processed aluminum alloy sheet.

[0178] The aluminum alloy sheet mentioned in step one is 5A06 aluminum alloy with a thickness of 2mm;

[0179] II. Cutting the middle layer:

[0180] Take the intermediate layer material and cut it to the same size as the connecting area of ​​the aluminum alloy plate. During the cutting process, ensure that the intermediate layer material is free of contamination and wrinkles to obtain the cut intermediate layer material.

[0181] The intermediate layer material mentioned in step two is Cu foil with a thickness of 10 μm;

[0182] III. Blank Assembly:

[0183] Place the cut interlayer material into the connecting area between the two aluminum alloy plates obtained in step two, forming a "sandwich" structure blank of aluminum alloy plate-interlayer material-aluminum alloy plate. The assembled structure is as follows: Figure 1 As shown;

[0184] IV. Welding and sealing:

[0185] The "sandwich" structure blank of aluminum alloy plate-intermediate layer material-aluminum alloy plate is sealed and welded around its perimeter. A small opening is left at one end, and a pure aluminum capillary tube with a diameter of Φ6 is welded. The welding process ensures that the weld seam is completely sealed, and the joint surface can only be connected to the outside through the capillary tube to obtain the sealed aluminum alloy plate assembly.

[0186] V. Vacuuming:

[0187] Connect the air pipe on the aluminum alloy plate assembly after the outer surface is coated with a release agent to a vacuum pump, and then evacuate the connection interface to 1 Pa to obtain the aluminum alloy plate assembly after evacuation.

[0188] VI. High-temperature rolling:

[0189] After the vacuum is removed, the aluminum alloy sheet is rolled at room temperature with a rolling speed of 200 mm / s and a rolling reduction of 30%. After the rolling is completed, the rolling mill is shut down and the connected aluminum alloy sheet is taken out.

[0190] VII. Post-processing:

[0191] The connecting process area around the plate is removed to obtain the target connecting plate, thus completing the high-temperature rolling rapid connection method for aluminum alloy plates.

[0192] The Cu interlayer material obtained in Comparative Example 4, and the sample after room temperature rolling bonding, are shown below. Figure 11 As shown, after the welding process area was cut off, the plates separated directly without forming a connection.

[0193] Comparative Example 5: This comparative example differs from Example 1 in that it uses a 100t three-beam four-column hydraulic press in conjunction with a heating furnace for high-temperature static pressure diffusion bonding. During the bonding process, the heating and pressurization of the plates are carried out simultaneously. The diffusion bonding time is 1 hour, and it is specifically completed according to the following steps:

[0194] 1. Grind the 2mm thick 5A06 aluminum alloy sheet to be joined to a smooth surface, remove contaminants, clean it with anhydrous ethanol, and blow it dry for later use.

[0195] 2. Take oxygen-free copper foil with a thickness of 10μm and cut it into the same shape according to the size of the connection area of ​​the aluminum alloy plate. During the cutting process, ensure that the copper foil is free from contamination and wrinkles.

[0196] 3. Take the prepared sheet material from step 1, lay the cut copper foil from step 2 on the area of ​​the aluminum alloy plate to be connected, and place another plate on top of the copper foil to form a "sandwich" structure of aluminum alloy plate-copper foil-aluminum alloy plate.

[0197] 4. Use argon arc welding to seal the four sides of the blank assembled in step 3, leave a small opening at one end, and weld a pure aluminum capillary tube with a diameter of Φ6mm. During the welding process, ensure that the weld is completely sealed, and the joint surface can only be connected to the outside through the capillary tube.

[0198] 5. Spray a layer of boron nitride protective agent on the outer surface of the welded aluminum alloy plate to prevent the aluminum alloy plate from sticking to the mold during rolling;

[0199] 6. Place the aluminum alloy sheet with connection from step 5 into the diffusion connection professional mold, and adjust the distance between the hydraulic press head and the upper mold to avoid the pressure from the expansion of the press head and premature contact with the mold during heating, which would cause the sheet to break.

[0200] 7. Connect the other end of the capillary tube on the plate in step 6 to the vacuum pump, and evacuate the connection interface to below 1 Pa.

[0201] 9. Slowly lower the hydraulic press head until the pressure on the plate reaches 3MPa, then maintain the temperature and pressure for 1 hour.

[0202] 10. Once the diffusion connection is complete, raise the hydraulic press head, open the furnace door, and cool to 100℃. To prevent the furnace body, heating pipes, and mold from cracking due to excessively rapid cooling, the furnace door can only be opened through a narrow seal. The entire cooling process takes approximately 5 hours.

[0203] 11. Fully open the furnace door, turn off the mechanical vacuum pump, and further air-cool to below 40°C before removing the aluminum alloy sheet after diffusion bonding is completed;

[0204] 12. Cut off the connecting process area around the board to obtain the target connecting board.

[0205] The aluminum alloy connection interface obtained in Comparative Example 5 is as follows Figure 12 As shown in the figure, Cu undergoes significant diffusion during hydrostatic diffusion, forming a good metallurgical bond. Its shear strength is as follows: Figure 13 As shown, its shear strength is close to that of Example 1. However, the entire diffusion bonding process using this method takes more than 7 hours, which is 10 times longer than that of Example 1. Furthermore, the plate bonding dimensions under this method are limited by the press platform, and only one part can be produced per thermal cycle, resulting in low production efficiency, extremely high production costs, and making mass production impossible.

Claims

1. A method for rapid connection of aluminum alloy sheets by high-temperature rolling, characterized in that... The method is specifically implemented according to the following steps: I. Blank processing: Cut aluminum alloy sheets to the appropriate size according to actual processing needs, then grind the sheets flat, clean and dry them to obtain the processed aluminum alloy sheets. II. Applying a release agent: Apply peelable adhesive to the surface of the joint area of ​​the treated aluminum alloy sheet, and then spray release agent on the surface of the non-joint area. After spraying, peel off the peelable adhesive. If the treated aluminum alloy sheet is fully joined, there is no need to apply peelable adhesive or spray release agent.

3. Trim the middle layer: Take the intermediate layer material and cut it to the same size as the connecting area of ​​the aluminum alloy plate to obtain the cut intermediate layer material. IV. Blank Assembly: Place the cut intermediate layer material in the connection area between the two aluminum alloy plates obtained in step two to form a "sandwich" structure blank of aluminum alloy plate-intermediate layer material-aluminum alloy plate. V. Welding and sealing: The "sandwich" structure blank of aluminum alloy plate-intermediate layer material-aluminum alloy plate is sealed and welded around its perimeter, and an opening is reserved for welding an air pipe with a valve. This allows the surfaces to be connected to the air pipe while being isolated from the outside, forming a sealed cavity, and thus obtaining the sealed aluminum alloy plate assembly. VI. Apply protective agent: A release agent is sprayed onto the outer surface of the sealed aluminum alloy plate assembly to prevent the aluminum alloy plate from sticking to the rolls during rolling, resulting in an aluminum alloy plate assembly with the release agent sprayed onto the outer surface. VII. Vacuuming: Connect the air pipe on the aluminum alloy plate assembly after the outer surface is coated with a release agent to a vacuum pump, and then evacuate the connection interface to obtain the aluminum alloy plate assembly after evacuation.

8. High-temperature rolling: After the vacuum is removed, the aluminum alloy plate assembly is placed in a heating furnace. After it is heated to the process temperature, it is sent to a rolling mill for high-temperature rapid rolling and connection. After cooling, the connected plate is obtained. IX. Post-processing: After cutting off the four sides of the connecting process area of ​​the plate after connection, the target connecting plate is obtained, thus completing the high-temperature rolling rapid connection method of aluminum alloy plates.

2. The method for rapid connection of aluminum alloy sheet by high-temperature rolling according to claim 1, characterized in that... The width of the peelable adhesive mentioned in step two is 5mm to 10mm.

3. The method for rapid connection of aluminum alloy sheet by high-temperature rolling according to claim 1, characterized in that... The isolating agent mentioned in step two is boron nitride.

4. The method for rapid connection of aluminum alloy sheet by high-temperature rolling according to claim 1, characterized in that... The isolating agent mentioned in step six is ​​boron nitride.

5. The method for rapid connection of aluminum alloy sheet by high-temperature rolling according to claim 1, characterized in that... In step seven, a vacuum is drawn at the connection interface until the vacuum level is below 100 Pa.

6. The method for rapid connection of aluminum alloy sheet by high-temperature rolling according to claim 1, characterized in that... The intermediate layer material mentioned in step three is copper foil, nickel foil, zinc sheet, or silver foil; the thickness of the intermediate layer material is 5μm~50μm.

7. The method for rapid connection of aluminum alloy sheet by high-temperature rolling according to claim 6, characterized in that... When the intermediate layer material is copper foil, the rolling temperature in step eight is 510℃~570℃, the rolling reduction is 5%~50%, and the instantaneous temperature of the connection interface should reach or exceed 548℃.

8. The method for rapid connection of aluminum alloy sheet by high-temperature rolling according to claim 6, characterized in that... When the intermediate layer material is nickel foil, the rolling temperature in step eight is 580℃~640℃, the rolling reduction is 5%~50%, and the instantaneous temperature of the connection interface should reach or exceed 640℃.

9. A method for rapid connection of aluminum alloy sheets by high-temperature rolling according to claim 6, characterized in that... When the intermediate layer material is zinc sheet, the rolling temperature in step eight is 350℃~420℃, the rolling reduction is 5%~50%, and the instantaneous temperature of the connection interface should reach or exceed 380℃.

10. A method for rapid connection of aluminum alloy sheets by high-temperature rolling according to claim 6, characterized in that... When the intermediate layer material is silver foil, the rolling temperature in step eight is 520℃~580℃, the rolling reduction is 5%~50%, and the instantaneous temperature of the connection interface should reach or exceed 566℃.

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