Aluminum alloy sheet hot-cold die combined heat treatment method

Abstract

The present application relates to non-ferrous metal processing technical field, specifically provide a kind of aluminium alloy sheet hot cold die composite heat treatment method.The aluminium alloy sheet hot cold die composite heat treatment method provided by the present application includes the following steps:S1.workpiece is placed in quenching device, and the workpiece is closed and clamped using upper and lower split heating die, is kept at 400-550 DEG C for 5-20min to carry out solid solution treatment;S2.the workpiece after solid solution treatment is transferred to cooling station, and the workpiece after solid solution treatment is closed and clamped using upper and lower split cooling die to carry out quenching treatment, and finished product is obtained;Wherein, the temperature of the upper and lower cooling die is controlled at 15-25 DEG C.The present application is by using the continuous processing mode of upper and lower split hot and cold die combination, so that the effective support of die is obtained in the whole process of solid solution and quenching for sheet, so that the deficiency of traditional air cushion furnace process in plate shape control and performance uniformity is successfully overcome, and then high-quality aluminium alloy sheet with flat plate shape and uniform structure can be stably prepared.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal processing technology, and in particular to a hot-cold mold composite heat treatment method for aluminum alloy thin plates. Background Technology

[0002] In the field of aerospace vehicle manufacturing, thin-walled structures are widely used to balance the core requirements of structural strength, service life and weight control. Among them, key components such as frames, beams, webs, partitions, panels and skins use a large number of aluminum alloy thin plates. The thickness of these thin plates is mainly concentrated in 0.6-2.0mm, so as to maximize the weight reduction of the aircraft structure and provide support for the lightweight development of aerospace technology.

[0003] In recent years, although China has developed the production capacity for aluminum alloy sheets with a thickness of 0.3mm or more, in actual production, thin sheets with a thickness of 0.3-0.5mm face serious problems of shape deformation and surface damage after quenching. Even after solution quenching in an air cushion furnace and subsequent online straightening, obvious defects such as central wavy lines, wrinkles, and scratches on the lower surface are still commonly found on the sheet surface, resulting in a low overall yield, large quality fluctuations, and extended delivery cycles. These problems mainly stem from the insufficient adaptability of existing air cushion furnace processes to ultra-thin sheets: Regarding sheet shape control, ultra-thin sheets exhibit a sinusoidal shape during air cushion levitation; the thinner the sheet, the greater the waveform amplitude. Furthermore, due to the sheet's own weight, the heated sheet always tends to deform downwards, making it difficult to maintain a stable floating height, resulting in uncontrollable plastic deformation during heating and cooling. On the other hand, uniform cooling is difficult to achieve during the quenching process of ultra-thin sheets. When the sheet enters the cooling stage after solution heating, the material is in a state of alternating hot and cold, causing a rapid change in rheological stress. At this time, the impact distribution of the nozzle liquid flow on the sheet surface is uneven, and the inconsistent shrinkage in different areas during cooling results in significant differences in local cooling rates. For ultra-thin sheets, this uneven cooling has a particularly prominent impact, easily leading to uneven distribution of microstructure and properties. This, in turn, causes defects such as strip breakage and deviation during subsequent straightening due to stress concentration, significantly reducing the yield of 0.3-0.5mm thick sheets.

[0004] Currently, the yield rate of 0.2-0.5mm thick aluminum alloy sheets produced by domestic aluminum alloy manufacturers is generally maintained at around 10%, and in some cases even lower. The production process frequently results in the scrapping of entire batches of materials, leading to significantly extended supply cycles and delivery difficulties. This is especially true for 0.3mm thick quenched sheets, where procurement channels are extremely unstable, making it difficult to meet the schedule requirements of existing and new aerospace vehicle development and production. Therefore, developing a high-precision, high-uniformity heat treatment process suitable for ultra-thin aluminum alloy sheets is of significant practical importance for improving sheet quality and yield. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a hot-cold mold composite heat treatment method for aluminum alloy thin plates. By employing a continuous processing method combining upper and lower split hot and cold molds, the plate material receives effective mold support throughout the solution treatment and quenching processes, thereby producing high-quality aluminum alloy thin plates with flat shapes and uniform microstructure.

[0006] In a first aspect, the present invention provides a method for combined hot and cold mold heat treatment of aluminum alloy thin plates, comprising the following steps:

[0007] S1. Place the workpiece in a quenching device, and use an upper and lower split heating mold to close and clamp the workpiece, and keep it at 400-550℃ for 5-20 minutes for solution treatment.

[0008] S2. The solution-treated workpiece is transferred to the cooling station, and the solution-treated workpiece is clamped in a closed cooling mold to perform quenching treatment to obtain the finished product; wherein the temperature of the upper and lower cooling molds is controlled at 15-25℃.

[0009] This invention employs a split-type heating mold and a split-type cooling mold to achieve continuous solution treatment and quenching of the sheet metal. During the solution treatment and quenching process, the mold provides effective support for the sheet metal throughout the process, precisely controlling its shape until it cools to room temperature (15–25℃). This effectively suppresses the sagging deformation of the ultra-thin sheet metal due to its own weight, avoiding the shape control problems such as the formation of sinusoidal waves due to sheet metal floating and wrinkles caused by cooling contraction in traditional air cushion furnaces. This ensures that the straightness of the finished aluminum alloy sheet metal is stably controlled within 0.1 mm / m, solving the problem of sheet metal shape control for ultra-thin aluminum alloy sheet metal.

[0010] This invention relies on the rigid structure and clamping pressure of an upper and lower split mold to ensure full and tight contact between the mold surface and the sheet metal surface, establishing a uniform heat conduction interface. During the solution treatment stage, the heating mold ensures precise temperature control of the sheet metal within the range of 450-550℃, achieving synchronized heating and uniform heat preservation, ensuring sufficient re-dissolution of solute atoms while preventing overheating. During the quenching stage, the cooling mold achieves rapid and uniform cooling at a stable low temperature, ensuring that the cooling start temperature is higher than the quenching sensitivity temperature and reaches the required cooling rate, preventing the precipitation of coarse equilibrium phases. Furthermore, due to the high thermal conductivity of aluminum alloys and the extremely rapid heat dissipation of thin sheets, the solution-treated sheet metal must be transferred to the cooling station within seconds; otherwise, a sudden temperature drop will occur, affecting the solution treatment effect. However, existing die-pressing quenching technology struggles to achieve rapid transfer and precise positioning of long coils (single section lengths exceeding 5m), causing premature temperature drops in thin sheets and triggering unfavorable phase transformations. This invention, through a segmented hot-cold mold combination device, successfully achieves rapid roller conveying of the plate after solution treatment and precise positioning within the cooling mold. It breaks through the technical bottleneck of continuous partitioned quenching of large-size thin plates, ultimately obtaining long-length aluminum alloy thin plates with sufficient solution treatment and excellent microstructure and properties. The surface roughness of the finished plate is ≤10μm, and the microstructure and properties are highly consistent, significantly reducing the production risks such as strip breakage and deviation caused by uneven properties. It successfully realizes high-quality continuous production of long-length aluminum alloy thin plates.

[0011] Preferably, in step S1, the workpiece is a rolled aluminum alloy sheet with a thickness of 0.2-2 mm.

[0012] Preferably, the aluminum alloy sheet is selected from 2xxx series aluminum alloys, such as 2A12 aluminum alloy, 2A14 aluminum alloy, 2024 aluminum alloy, etc.

[0013] Preferably, in step S1, the opening and closing speed of the upper and lower split heating mold is 40-60 mm / min.

[0014] Preferably, in step S2, the time for transferring the workpiece to the cooling station after solution treatment does not exceed 5 seconds.

[0015] Preferably, in step S2, the opening and closing speed of the upper and lower split cooling mold is 40-60 mm / min.

[0016] Preferably, in step S2, the quenching treatment time is 5-20 minutes. More preferably, the quenching treatment time is the same as the solution treatment time, ensuring that the heat in the core of the plate is fully dissipated, thereby achieving uniform cooling and phase transformation of the entire cross-section of the plate, effectively avoiding the deterioration of the core properties due to insufficient cooling, and obtaining a finished product with more consistent microstructure and properties; at the same time, it allows the solution treatment and quenching to start and complete simultaneously in time, enabling continuous production and greatly improving production efficiency.

[0017] Preferably, in step S2, after the quenching process is completed, the process further includes coiling and slitting.

[0018] Secondly, the present invention also provides an aluminum alloy sheet, which is prepared by the hot and cold mold composite heat treatment method for aluminum alloy sheets provided by the present invention.

[0019] Preferably, the aluminum alloy sheet is selected from 2xxx series aluminum alloys, such as 2A12 aluminum alloy, 2A14 aluminum alloy, 2024 aluminum alloy, etc.

[0020] Thirdly, the present invention also provides a quenching apparatus for the above-mentioned hot and cold mold combined heat treatment method for aluminum alloy thin plates, comprising:

[0021] A traction structure, comprising a feeding roller and a receiving roller, is used to drive the workpiece to move.

[0022] The heating station is equipped with an upper and lower split heating mold, which includes an upper heating mold and a lower heating mold that can move towards or away from each other. The upper heating mold and the lower heating mold are equipped with electric heating elements.

[0023] The cooling station is equipped with an upper and lower split cooling mold, which includes an upper cooling mold and a lower cooling mold that can move towards or away from each other. The upper and lower cooling molds are equipped with water-cooling elements.

[0024] Preferably, the upper heating mold and the lower heating mold further include a temperature controller. The temperature controller is used to detect the temperature and control the temperature of the upper and lower split heating molds to ensure that the solid solution temperature is accurate and stable, which can prevent incomplete solid solution caused by insufficient temperature and avoid overheating defects caused by excessive temperature.

[0025] Preferably, the upper and lower cooling molds further include a temperature controller, which is used to detect the temperature and control the temperature of the upper and lower split cooling molds to ensure a stable low temperature during continuous production and achieve effective quenching.

[0026] Preferably, the traction speed of the traction structure is 0.5-5 m / s.

[0027] Preferably, the mold material for the upper and lower split heating mold and the upper and lower split cooling mold is mold steel.

[0028] The hot and cold mold composite heat treatment method for aluminum alloy thin plates provided by this invention has the following advantages compared with the prior art:

[0029] This invention employs a continuous processing method combining upper and lower split hot and cold molds, ensuring effective mold support throughout the solution treatment and quenching process. This successfully overcomes the shortcomings of traditional air cushion furnace processes in terms of plate shape control and performance uniformity, enabling the stable production of high-quality aluminum alloy thin plates with flat shapes and uniform microstructures. This method combines continuous process flow with a high degree of automation, showing promising prospects for industrial application. Furthermore, this invention utilizes segmented hot and cold mold equipment to achieve rapid transfer and precise placement within 5 seconds after solution treatment, overcoming the problem of reduced solution treatment effect caused by the rapid thermal conductivity of aluminum alloys and the rapid temperature drop of thin plates in traditional die-press quenching. Ultimately, the finished plate exhibits a surface roughness ≤10μm and highly consistent microstructure and properties, achieving high-quality continuous production of large-length aluminum alloy thin plates. Attached Figure Description

[0030] Figure 1 This is a schematic diagram illustrating the process principle of the hot and cold mold composite heat treatment method for aluminum alloy thin plates provided in Embodiment 1 of the present invention.

[0031] Figure 2 This is a macroscopic morphology image of the finished aluminum alloy sheet obtained in Example 1 of the present invention;

[0032] Figure 3 This is a microscopic morphology image of the finished aluminum alloy sheet obtained in Example 1 of the present invention. Detailed Implementation

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the specific embodiments will be briefly introduced below. Obviously, the embodiments described below are some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these embodiments without creative effort.

[0034] Where specific experimental steps or conditions are not specified in the embodiments, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. All raw materials or instruments used are commercially available conventional products, including but not limited to those used in the embodiments of this application.

[0035] Example 1

[0036] This embodiment provides a hot and cold mold composite heat treatment method for 2024 aluminum alloy thin plates, and the process principle diagram is shown below. Figure 1 As shown, the steps include:

[0037] (1) Install the 0.3mm thick 2024 aluminum alloy sheet in coil onto the feeding roller and pull it to the receiving roller. Set the conveying speed to 2.5 m / s. When the sheet enters the heating station, the feeding roller and the receiving roller stop moving. The upper heating mold and the lower heating mold close at a speed of 50mm / min to make the mold fully contact the sheet. The sheet is heated to 495℃ and kept at that temperature for 5.5min for solution treatment. The heating area is 1.5m*5m.

[0038] (2) After the solution treatment is completed, the upper heating mold and the lower heating mold are opened at a speed of 50 mm / min, and the feeding roller and the receiving roller are restarted. The solution-treated plate is transferred to the cooling station within 3 seconds. After the plate enters the cooling station, the feeding roller and the receiving roller are stopped again, and the upper cooling mold and the lower cooling mold are closed at a speed of 50 mm / min. The upper and lower cooling molds are used to achieve rapid cooling of the plate and complete the quenching treatment. The temperature of the upper cooling mold and the lower cooling mold is set to 25℃, the holding time is 5.5 min, and the heating area is 1.5m*5m.

[0039] (3) Open the upper cooling mold and the lower cooling mold at a speed of 50 mm / min, start the feeding roller and the receiving roller, and collect the quenched plate into the receiving roller within 3 seconds; after the whole roll is finished, unfold the roll, cut the area that has undergone hot and cold mold composite heat treatment into the required size for later use, and cut off the junction area of ​​the thin plate that has not undergone hot and cold mold composite heat treatment to ensure uniform microstructure and properties, and obtain the finished 2024 aluminum alloy thin plate.

[0040] The macroscopic morphology of the finished 2024 aluminum alloy sheet obtained in this embodiment is shown in the following figure. Figure 2 As shown, its microstructure is illustrated in the following diagram. Figure 3 As shown, the image was taken in secondary electron mode using a Thermo Fisher Scientific FEI-Apero scanning electron microscope, with a scale bar of 100 μm.

[0041] The finished 2024 aluminum alloy sheet prepared in this embodiment was tested using a coordinate measuring machine and a surface roughness measuring instrument. The straightness was 0.1 mm / m, the surface roughness was 9.5 μm, the sheet shape was good, and the performance was uniform.

[0042] This embodiment provides a quenching apparatus for the above-described hot and cold mold combined heat treatment method for aluminum alloy thin plates, comprising:

[0043] The traction structure includes a feeding roller and a receiving roller for driving the workpiece to move;

[0044] The heating station is equipped with an upper and lower split heating mold, which includes an upper heating mold and a lower heating mold that can move towards or away from each other. The upper and lower heating molds are equipped with electric heating elements. The upper and lower heating molds also include temperature controllers, which are used to detect the temperature and control the temperature of the upper and lower split heating molds to ensure that the set temperature is accurately reached. This prevents the temperature from being too low, which may lead to incomplete solidification, or from being too high, which may lead to overheating. The mold material is mold steel.

[0045] The cooling station is equipped with an upper and lower split cooling mold, which includes an upper cooling mold and a lower cooling mold that can move towards or away from each other. The upper and lower cooling molds are equipped with water-cooling components. The upper and lower cooling molds also include temperature controllers, which are used to detect and control the temperature of the upper and lower split cooling molds to prevent the mold temperature from rising during mass production and failing to quench effectively. The mold material is mold steel.

[0046] Example 2

[0047] This embodiment provides a hot and cold mold composite heat treatment method for 2024 aluminum alloy thin plates, including the following steps:

[0048] (1) Install the 0.5mm thick 2024 aluminum alloy sheet in coil onto the feeding roller and pull it to the receiving roller. Set the conveying speed to 3 m / s. When the sheet enters the heating station, the feeding roller and the receiving roller stop moving. The upper heating mold and the lower heating mold close at a speed of 50mm / min to make the mold fully contact the sheet. The sheet is heated to 505℃ and kept at that temperature for 9 minutes for solution treatment. The heating area is 1.5m*5m.

[0049] (2) After the solution treatment is completed, the upper heating mold and the lower heating mold are opened at a speed of 50 mm / min, and the feeding roller and the receiving roller are restarted. The solution-treated plate is transferred to the cooling station within 3 seconds. After the plate enters the cooling station, the feeding roller and the receiving roller are stopped again, and the upper cooling mold and the lower cooling mold are closed at a speed of 50 mm / min. The upper and lower cooling molds are used to achieve rapid cooling of the plate and complete the quenching treatment. The temperature of the upper cooling mold and the lower cooling mold is set to 25℃, the holding time is 9 min, and the heating area is 1.5m*5m.

[0050] (3) Open the upper cooling mold and the lower cooling mold at a speed of 50 mm / min, start the feeding roller and the receiving roller, and collect the quenched plate into the receiving roller within 3 seconds; after the whole roll is finished, unfold the roll, cut the area that has undergone hot and cold mold composite heat treatment into the required size for later use, and cut off the junction area of ​​the thin plate that has not undergone hot and cold mold composite heat treatment to ensure uniform microstructure and properties, and obtain the finished 2024 aluminum alloy thin plate.

[0051] The finished 2024 aluminum alloy sheet prepared in this embodiment was tested using a coordinate measuring machine and a surface roughness measuring instrument. The straightness was 0.09 mm / m, the surface roughness was 9.3 μm, the sheet shape was good, and the performance was uniform.

[0052] The quenching apparatus used in this embodiment is the same as that in Embodiment 1.

[0053] Example 3

[0054] This embodiment provides a hot and cold mold composite heat treatment method for 2A12 aluminum alloy thin plates, including the following steps:

[0055] (1) Install the 0.2mm thick 2A12 aluminum alloy sheet in coil onto the feeding roller and pull it to the receiving roller. Set the conveying speed to 1 m / s. When the sheet enters the heating station, the feeding roller and the receiving roller stop moving. The upper heating mold and the lower heating mold close at a speed of 50mm / min to make the mold fully contact the sheet. The sheet is heated to 485℃ and kept at that temperature for 3 minutes for solution treatment. The heating area is 1.5m*5m.

[0056] (2) After the solution treatment is completed, the upper heating mold and the lower heating mold are opened at a speed of 50 mm / min, and the feeding roller and the receiving roller are restarted. The solution-treated plate is transferred to the cooling station within 3 seconds. After the plate enters the cooling station, the feeding roller and the receiving roller are stopped again, and the upper cooling mold and the lower cooling mold are closed at a speed of 50 mm / min. The upper and lower cooling molds are used to achieve rapid cooling of the plate and complete the quenching treatment. The temperature of the upper cooling mold and the lower cooling mold is set to 25℃, the holding time is 3 min, and the heating area is 1.5m*5m.

[0057] (3) Open the upper cooling mold and the lower cooling mold at a speed of 50 mm / min, start the feeding roller and the receiving roller, and collect the quenched plate into the receiving roller within 3 seconds; after the whole roll is finished, unfold the roll, cut the area that has undergone hot and cold mold composite heat treatment into the required size for later use, and cut off the junction area of ​​the thin plate that has not undergone hot and cold mold composite heat treatment to ensure uniform microstructure and properties, and obtain the finished 2A12 aluminum alloy thin plate.

[0058] The finished 2A12 aluminum alloy sheet prepared in this embodiment was tested using a coordinate measuring machine and a surface roughness measuring instrument. The straightness was 0.08 mm / m, the surface roughness was 9.7 μm, the sheet shape was good, and the performance was uniform.

[0059] The quenching apparatus used in this embodiment is the same as that in Embodiment 1.

[0060] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method of hot-cold die combined heat treatment of an aluminum alloy sheet, characterized by, Includes the following steps: S1. Place the workpiece in a quenching device, and use an upper and lower split heating mold to close and clamp the workpiece, and keep it at 400-550℃ for 5-20 minutes for solution treatment. S2. The solution-treated workpiece is transferred to the cooling station, and the solution-treated workpiece is clamped in a closed cooling mold with upper and lower openings for quenching treatment to obtain the finished product; wherein the temperature of the upper cooling mold and the lower cooling mold is controlled at 15-25℃. The upper and lower split heating mold and the upper and lower split cooling mold are arranged sequentially from the feeding roller to the receiving roller; In step S1, the opening and closing speed of the upper and lower split heating mold is 40-60 mm / min; In step S2, the opening and closing speed of the upper and lower split cooling mold is 40-60 mm / min.

2. The method of claim 1, wherein the aluminum alloy sheet is a 6xxx series aluminum alloy sheet. The workpiece is a rolled aluminum alloy sheet with a thickness of 0.2-2mm.

3. The method of claim 1, wherein the aluminum alloy sheet is a 6xxx series aluminum alloy sheet. In step S2, the time for the workpiece to be transferred to the cooling station after solution treatment does not exceed 5 seconds.

4. The method of claim 1, wherein the aluminum alloy sheet is a 6xxx series aluminum alloy sheet. In step S2, the quenching process takes 5-20 minutes.

5. An aluminum alloy sheet, characterized by, It is prepared by the hot and cold mold composite heat treatment method of aluminum alloy sheet according to any one of claims 1-4.

6. A quenching apparatus for the hot-cold mold combined heat treatment method for aluminum alloy thin plates according to any one of claims 1-4, comprising: A traction structure, comprising a feeding roller and a receiving roller, is used to drive the workpiece to move. The heating station is equipped with an upper and lower split heating mold, which includes an upper heating mold and a lower heating mold that can move towards or away from each other. The upper heating mold and the lower heating mold are equipped with electric heating elements. The cooling station is equipped with an upper and lower split cooling mold, which includes an upper cooling mold and a lower cooling mold that can move towards or away from each other. The upper and lower cooling molds are equipped with water-cooling elements. The upper and lower split heating mold and the upper and lower split cooling mold are arranged sequentially along the receiving direction of the receiving roller.

7. The quenching apparatus of claim 6, wherein The upper heating mold and the lower heating mold also include a temperature controller, which is used to detect the temperature and control the temperature of the upper and lower split heating molds.

8. The quenching apparatus of claim 6, wherein The traction speed of the traction structure is 0.5-5 m / s.

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