A method for preparing a low-die-ratio 6061-o state aluminum alloy plate

Abstract

The application relates to a preparation method of a 6061-O state aluminum alloy plate with a low earing rate, which comprises the following steps: (1) melting and casting; (2) milling; (3) heating; (4) hot continuous rolling; (5) product annealing; and (6) shearing. In the melting and casting step, the mass percentage of the chemical composition of the aluminum alloy is controlled as follows: Si: 0.4-0.8%, Fe: <=0.7%, Cu: 0.15-0.4%, Mn: <=0.15%, Mg: 0.8-1.2%, Cr: 0.04-0.35%, Zn: <=0.25%, Ti: <=0.15%, other impurity elements: <=0.05% each, other impurity elements: <=0.15% in total, and the balance is Al, and the total is 100%. The method adjusts the texture type and strength of the balanced product by optimizing the chemical composition of the aluminum alloy, optimizing the hot continuous rolling process and optimizing the product annealing process, so that the earing rate is reduced.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy sheet processing technology, specifically to a method for preparing a low-ear-forming 6061-O state aluminum alloy sheet. Background Technology

[0002] 6061 aluminum alloy's main alloying elements are Al-Mg-Si. It belongs to the heat-treatable aluminum alloy category and possesses moderate strength, good plasticity, corrosion resistance, weldability, and formability. It is widely used in aerospace, transportation, automotive manufacturing, and mechanical stamping. With increasing environmental awareness, lightweight materials have become a social development trend. Due to its excellent stamping performance, 6061-O aluminum alloy is widely used in hydrogen energy storage tanks, oxygen tanks, and other fields. Reducing the lug rate of 6061-O aluminum alloy to improve the yield of stamped parts has become an urgent market demand.

[0003] Chinese patent CN202210632213 discloses an Al-Mg alloy thin plate and a rolling method for reducing the ear-forming rate of Al-Mg alloy thin plates. The Al-Mg alloy thin plate is obtained by sequentially hot rolling and cold rolling Al-Mg alloy ingots. Among them, the total reduction rate of hot rolling is ≥95%, the hot rolling temperature is 220~300℃, and the total reduction rate of cold rolling is ≥90%. All three conditions are indispensable. The control method has a long production cycle and low efficiency.

[0004] Chinese patent CN202010233523 discloses a production process for 5052 aluminum alloy sheet with low lug rate. By reasonably controlling the content of alloying elements and adjusting the homogenization process of the ingot, the size of the second phase in the ingot is changed by appropriately increasing the homogenization temperature. This improves the microstructure distribution of subsequent cold rolling deformation and O-state annealing, and increases the nucleation points during recrystallization, promoting the uniform distribution of grains and thus reducing the anisotropy of the material. The production process requires ingot homogenization annealing and cold rolling, resulting in high production costs.

[0005] Chinese patent CN201811623718 discloses an aluminum strip for capacitor casings with low ear-forming rate and its preparation method. The method involves controlling the fabric texture ratio of the billet by self-annealing at the hot rolling final rolling temperature, and then controlling the fabric texture balance of the finished product by controlling the cold rolling processing rate, thereby obtaining an aluminum strip for capacitor casings with low ear-forming rate. The preparation method includes ingot casting homogenization annealing, intermediate annealing, and cold rolling, which has a long production cycle and high cost.

[0006] To address the shortcomings of existing technologies, such as long production cycles and high costs, this invention addresses these issues by rationally controlling the hot continuous rolling process. This involves designing aspects such as the initial rolling temperature, intermediate billet temperature, the reduction allowance from the intermediate billet to the finished product, the number of rolling passes, the final rolling temperature of the hot finishing roll, and the management of lubrication and cooling media. By controlling the texture ratio of the hot-rolled billet and then using finished product annealing to adjust the texture balance, this invention achieves efficient production of aluminum alloy sheets with low lug rate and high deep-drawing performance.

[0007] This invention provides a method for preparing 6061-O state aluminum alloy sheet with low ear-forming rate, which is suitable for aluminum alloy sheet products for stamping. The produced products have uniform microstructure and the ear-forming rate after stamping is less than 2.5%. Furthermore, the preparation method of this invention has the advantages of short process, low cost and high stability. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for preparing low-ear-ratio 6061-O state aluminum alloy sheets that is short-process, low-cost, highly stable, produces products with uniform microstructure, and has an ear-forming rate of less than 2.5% after stamping. This method is suitable for producing aluminum alloy sheets for stamping.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for preparing a low-ear-forming 6061-O state aluminum alloy sheet, the method comprising the following steps: (1) casting; (2) milling; (3) heating; (4) hot rolling; (5) finished product annealing; (6) shearing;

[0010] In step (1), the mass percentage of the aluminum alloy chemical composition is as follows: Si: 0.4-0.8%, Fe: ≤0.7%, Cu: 0.15-0.4%, Mn: ≤0.15%, Mg: 0.8-1.2%, Cr: 0.04-0.35%, Zn: ≤0.25%, Ti: ≤0.15%, other impurity elements ≤0.05% each, other impurity elements total ≤0.15%, and the balance is Al, totaling 100%.

[0011] In step (3), the heating temperature is 400-460℃ and the holding time is 3-24h;

[0012] In step (4), hot rolling is carried out in the 1+4 hot continuous rolling process. The equipment used in the process includes a 1-stand hot roughing mill and a 4-stand hot finishing mill. The ingot is rolled at a starting temperature of 400-460°C in the hot roughing mill. The hot roughing mill is rolled 17-23 times to obtain an intermediate billet with a thickness of 20-50 mm. The temperature of the intermediate billet is controlled at 320-360°C. The intermediate billet is then transferred to the hot finishing mill and rolled to a thickness of 2.5-7 mm in the hot finishing mill with 4 stands. The final rolling temperature is controlled at 190-220°C. The billet is then coiled and cooled offline.

[0013] In step (5), the roll material is sent to a box-type annealing furnace for two-stage annealing treatment. The furnace gas temperature for the first stage of annealing treatment is 515-525℃ and the time is 5.5-6.5h. The furnace gas temperature for the second stage of annealing treatment is 395-405℃ and the time is 2.8-3.2h.

[0014] Further, in step (1), the mass percentage of the aluminum alloy chemical composition is as follows: Si: 0.5-0.8%, Fe: ≤0.7%, Cu: 0.18-0.4%, Mn: ≤0.15%, Mg: 0.9-1.2%, Cr: 0.07-0.35%, Zn: ≤0.25%, Ti: ≤0.15%, other impurity elements individually ≤0.05%, other impurity elements total ≤0.15%, and the balance is Al, totaling 100%.

[0015] Further, in step (1), the prepared raw materials are added to the melting furnace and mixed evenly to melt into liquid aluminum alloy to obtain aluminum alloy melt. The aluminum alloy melt is transferred to the holding furnace and refined at 720-750℃ for 30-50 minutes. The refined aluminum alloy melt is then cast into aluminum alloy ingots with a thickness of 400-620mm.

[0016] Furthermore, in step (2), the aluminum alloy ingot is milled, with each large surface milled by 9 to 11 mm / surface, while the side surfaces are not milled.

[0017] Furthermore, in step (3), the heating temperature is 420-460℃ and the heat preservation time is 6-24h.

[0018] Furthermore, in step (4), the thickness of the intermediate billet is determined according to the thickness of the finished product, and needs to be reserved to a minimum of 85% of the reduction amount of the finished product thickness.

[0019] Furthermore, in step (4), the hot rolling process uses an emulsion for lubrication and cooling. The temperature of the emulsion during use is 50-65°C, and the pressure of the spraying system is 4-6 bar. The cooling device is located on the inlet side of the finishing mill. The emulsion is sprayed onto the plate through a fan-shaped nozzle to cool the plate entering the finishing mill to ensure the initial rolling temperature of the plate.

[0020] Furthermore, in step (4), the hot roughing mill inlet and outlet, the hot finishing mill 1 stand inlet and 4 stand outlet are all equipped with pyrometers to monitor the temperature of the plate in real time.

[0021] Furthermore, in step (4), the cooling method for the roll is to use a fan to cool both ends of the roll.

[0022] Furthermore, the rolled material is sent to a box-type annealing furnace for two-stage annealing treatment. The furnace gas temperature for the first stage annealing treatment is 520-525℃, and the time is 6-6.5h. The furnace gas temperature for the second stage annealing treatment is 400-405℃, and the time is 3-3.2h.

[0023] This invention discloses a method for preparing 6061-O state aluminum alloy sheet with low earing rate. Earing in aluminum alloy sheet stampings is caused by the formation of textured structures during processing. These textured structures exhibit significant anisotropy, leading to uneven deformation during stamping. Aluminum alloys are prone to forming rolling textures during rolling and cubic textures during full annealing. Rolling textures cause earing at approximately 45° to the rolling direction after stamping, while cubic textures cause earing at 0° / 90° to the rolling direction. This method optimizes the aluminum alloy chemical composition, hot rolling process, and finished product annealing process to adjust and balance the texture type and strength of the finished product, thereby reducing the earing rate.

[0024] This invention discloses a method for preparing 6061-O state aluminum alloy sheet with low lug rate. Hot rolling significantly influences the formation of the sheet's texture. During rolling, the lattice orientation of the sheet grains changes along the deformation direction, forming the rolling texture. When the hot rolling temperature is above the recrystallization temperature, the sheet grains simultaneously undergo recovery and dynamic recrystallization, forming a cubic texture and weakening the rolling texture. The higher the hot rolling temperature, the more pronounced the weakening of the rolling texture. Therefore, hot-rolled billets typically exhibit a weak rolling texture and a strong cubic texture, resulting in lugs at 0° / 90° after stamping. Existing technologies control the texture balance of the finished product by reserving billet thickness and using cold rolling processing rate in subsequent processes. This invention achieves this by rationally controlling the aluminum alloy's chemical composition, optimizing the hot rolling process, and optimizing... The finishing annealing process employs a lower hot roughing rolling temperature to reduce the proportion of the original cubic texture in the intermediate billet, controls the intermediate billet temperature below the recrystallization temperature, and reserves ≥85% reduction from the intermediate billet to the finished product. Rapid cooling of the emulsion during hot finishing rolling ensures no recrystallization of the sheet material, resulting in a hot-rolled billet with a predominantly rolled texture. Furthermore, the final rolling temperature of the hot finishing rolling is controlled between 190 and 220°C to prevent the consumption of a large amount of rolled texture due to high-temperature self-annealing after the billet leaves the production line. Finally, the finished product annealing utilizes a two-stage annealing process in a box-type annealing furnace, efficiently and quickly reaching the annealing temperature to achieve a balanced texture type and strength. The finished sheet exhibits a low earing rate, fine and uniform grains, and excellent deep-drawing performance.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. The method for preparing 6061-O state aluminum alloy sheet with low earing rate disclosed in this invention designs aspects such as hot continuous rolling start temperature, hot continuous rolling intermediate billet temperature, reduction allowance from intermediate billet to finished product, rolling passes, hot finishing rolling finish temperature, and lubrication and cooling medium management. It optimizes the texture type and strength of hot continuous rolled billet, and then uses finished product annealing to control texture balance. This solves the current industry problem of high earing rate in the 0° / 90° direction of hot rolled billet, and provides a new idea and direction for further reducing the overall production cost of aluminum processing products.

[0027] 2. The method for preparing low-ear-forming 6061-O state aluminum alloy sheet disclosed in this invention uses hot-rolled billets and finished product annealing to prepare sheet with low-ear-forming rate, reducing cold rolling processing steps and processing time, improving overall processing efficiency, shortening the overall production cycle of orders, reducing overall production and processing costs, and enhancing product market competitiveness. Attached Figure Description

[0028] Figure 1 The image shows a semi-finished oxygen cylinder obtained by stamping the sheet metal prepared in Example 1 of the present invention, illustrating that the ear-making rate of the finished sheet metal in Example 1 is low.

[0029] Figure 2 Images of oxygen cylinder semi-finished products obtained by stamping the sheet metal prepared in Example 2 of the present invention (left 1) and images of oxygen cylinder semi-finished products obtained by stamping the sheet metal prepared in Comparative Example 2 (right 1) are shown. It can be seen that the ear-making rate of the finished sheet metal in Example 2 is low, while the ear-making rate of the finished sheet metal in Comparative Example 2 is high. Detailed Implementation

[0030] The following embodiments can help those skilled in the art to more fully understand the present invention, but should not be construed as limiting the present invention in any way.

[0031] Example 1

[0032] This embodiment is a method for preparing a low-ear-forming 6061-O state aluminum alloy sheet, which includes the following production process: including the following steps: (1) casting; (2) milling; (3) heating; (4) hot rolling; (5) finished product annealing; (6) shearing.

[0033] (1) Melting and casting: The raw materials are mixed evenly in the melting furnace and melted into liquid aluminum alloy to obtain aluminum alloy melt. The aluminum alloy melt is transferred to the holding furnace and refined at 720°C for 30 minutes. The refined aluminum alloy melt is then cast into aluminum alloy ingots with a thickness of 400 mm.

[0034]

[0035] (2) Milling: Mill the aluminum alloy ingot, with each large surface milling amount of 9mm / surface, and the side surfaces are not milled, to obtain a milled aluminum alloy ingot.

[0036] (3) Heating: The milled aluminum alloy ingot is sent into a heating furnace and held at a heating temperature of 420°C for 10 hours to obtain a heat-treated aluminum alloy ingot.

[0037] (4) Hot continuous rolling: The heated aluminum alloy ingot is placed in a 1+4 hot continuous rolling process for hot continuous rolling. The equipment used in the process includes a 1-stand hot roughing mill and a 4-stand hot finishing mill. The ingot is rolled at 420°C in the hot roughing mill and rolled 19 times to obtain an intermediate billet with a thickness of 40mm. The thickness of the intermediate billet is determined according to the thickness of the finished product and a reduction of ≥85% of the thickness of the finished product is required. The temperature of the intermediate billet is controlled at 320°C. The intermediate billet is then transferred to the hot finishing mill and rolled to a thickness of 4mm in a 4-stand hot finishing mill. The final rolling temperature is controlled at 190°C. The billet is then coiled and cooled. The cooling method is to use a fan to cool both ends of the coil to obtain a cooled coil.

[0038] In the hot continuous rolling process, an emulsion is used for lubrication and cooling. The emulsion is used at a temperature of 50°C and the spraying system pressure is 4 bar. The cooling device is located on the inlet side of the finishing mill. The emulsion is sprayed onto the plate through a fan-shaped nozzle to cool the plate entering the finishing mill and ensure the plate's initial rolling temperature.

[0039] The hot roughing mill inlet and outlet, the hot finishing mill 1 stand inlet and 4 stand outlet are all equipped with pyrometers to monitor the plate temperature in real time; the plate direction is: hot roughing mill, hot finishing mill 1 stand, hot finishing mill 2 stand, hot finishing mill 3 stand, hot finishing mill 4 stand;

[0040] (5) Finished product annealing: The cooled coil is sent to a box annealing furnace for two-stage annealing treatment. The furnace gas temperature for the first stage annealing treatment is 520°C and the time is 6 hours. The furnace gas temperature for the second stage annealing treatment is 400°C and the time is 3 hours, to obtain finished annealed aluminum alloy coil.

[0041] (6) Shearing: The finished annealed aluminum alloy coil is sheared to obtain a low-earing rate 6061-O state aluminum alloy sheet.

[0042]

[0043] As can be seen from the data in the table above, the method of this application adjusts and balances the texture type and strength of the finished product by optimizing the chemical composition of aluminum alloy, optimizing the hot rolling process, and optimizing the finished product annealing process, thereby achieving the purpose of reducing the ear-making rate.

[0044] Example 2

[0045] This embodiment is a method for preparing a low-ear-forming 6061-O state aluminum alloy sheet, which includes the following production process: including the following steps: (1) casting; (2) milling; (3) heating; (4) hot rolling; (5) finished product annealing; (6) shearing.

[0046] (1) Melting and casting: The raw materials are mixed according to the following mass percentages; the prepared raw materials are added to the melting furnace and mixed evenly to melt into liquid aluminum alloy to obtain aluminum alloy melt. The aluminum alloy melt is transferred to the holding furnace and refined at 750℃ for 50 minutes. The refined aluminum alloy melt is then cast into aluminum alloy ingots with a thickness of 620mm.

[0047]

[0048]

[0049] (2) Milling: Mill the aluminum alloy ingot, with each large surface milled by 11mm / surface, and the side surfaces not milled, to obtain a milled aluminum alloy ingot.

[0050] (3) Heating: The milled aluminum alloy ingot is sent into a heating furnace and held at a heating temperature of 450°C for 8 hours to obtain a heat-treated aluminum alloy ingot.

[0051] (4) Hot continuous rolling: The heated aluminum alloy ingot is placed in a 1+4 hot continuous rolling process for hot continuous rolling. The equipment used in the process includes a 1-stand hot roughing mill and a 4-stand hot finishing mill. The ingot is rolled at a starting temperature of 450°C in the hot roughing mill. The hot roughing mill is rolled 21 times to obtain an intermediate billet with a thickness of 32mm. The thickness of the intermediate billet is determined according to the thickness of the finished product. It is necessary to reserve a reduction of ≥85% to the thickness of the finished product. The temperature of the intermediate billet is controlled at 350°C. The intermediate billet is then transferred to the hot finishing mill and rolled to a thickness of 3.0mm in a 4-stand hot finishing mill. The final rolling temperature is controlled at 210°C. The billet is then coiled and cooled off the line. The cooling method is to use a fan to cool both ends of the coil to obtain a cooled coil.

[0052] In the hot continuous rolling process, an emulsion is used for lubrication and cooling. The emulsion is used at a temperature of 65°C and the spraying system pressure is 6 bar. The cooling device is located on the inlet side of the finishing mill. The emulsion is sprayed onto the plate through a fan-shaped nozzle to cool the plate entering the finishing mill and ensure the plate's initial rolling temperature.

[0053] The hot roughing mill inlet and outlet, the hot finishing mill 1 stand inlet and 4 stand outlet are all equipped with pyrometers to monitor the plate temperature in real time; the plate direction is: hot roughing mill, hot finishing mill 1 stand, hot finishing mill 2 stand, hot finishing mill 3 stand, hot finishing mill 4 stand;

[0054] (5) Finished product annealing: The cooled coil is sent to a box annealing furnace for two-stage annealing treatment. The furnace gas temperature for the first stage annealing treatment is 520°C and the time is 6 hours. The furnace gas temperature for the second stage annealing treatment is 400°C and the time is 3 hours, to obtain finished annealed aluminum alloy coil.

[0055] (6) Shearing: The finished annealed aluminum alloy coil is sheared to obtain a low-earing rate 6061-O state aluminum alloy sheet.

[0056]

[0057] As can be seen from the data in the table above, the method of this application adjusts and balances the texture type and strength of the finished product by optimizing the chemical composition of aluminum alloy, optimizing the hot rolling process, and optimizing the finished product annealing process, thereby achieving the purpose of reducing the ear-making rate.

[0058] Example 3

[0059] This embodiment is a method for preparing a low-ear-forming 6061-O state aluminum alloy sheet, which includes the following production process: including the following steps: (1) casting; (2) milling; (3) heating; (4) hot rolling; (5) finished product annealing; (6) shearing.

[0060] (1) Melting and casting: The raw materials are mixed evenly in the melting furnace and melted into liquid aluminum alloy to obtain aluminum alloy melt. The aluminum alloy melt is transferred to the holding furnace and refined at 720°C for 30 minutes. The refined aluminum alloy melt is then cast into aluminum alloy ingots with a thickness of 400 mm.

[0061]

[0062] (2) Milling: Mill the aluminum alloy ingot, with each large surface milling amount of 9mm / surface, and the side surfaces are not milled, to obtain a milled aluminum alloy ingot.

[0063] (3) Heating: The milled aluminum alloy ingot is sent into a heating furnace and held at a heating temperature of 400°C for 3 hours to obtain a heat-treated aluminum alloy ingot.

[0064] (4) Hot continuous rolling: The heated aluminum alloy ingot is placed in a 1+4 hot continuous rolling process for hot continuous rolling. The equipment used in the process includes a 1-stand hot roughing mill and a 4-stand hot finishing mill. The ingot is rolled at 400°C in the hot roughing mill and rolled 17 times to obtain an intermediate billet with a thickness of 20mm. The thickness of the intermediate billet is determined according to the thickness of the finished product and a reduction of ≥85% of the thickness of the finished product is required. The temperature of the intermediate billet is controlled at 320°C. The intermediate billet is then transferred to the hot finishing mill and rolled to a thickness of 2.5mm in a 4-stand hot finishing mill. The final rolling temperature is controlled at 190°C. The billet is then coiled and cooled. The cooling method is to use a fan to cool both ends of the coil to obtain a cooled coil.

[0065] In the hot continuous rolling process, an emulsion is used for lubrication and cooling. The emulsion is used at a temperature of 50°C and the spraying system pressure is 4 bar. The cooling device is located on the inlet side of the finishing mill. The emulsion is sprayed onto the plate through a fan-shaped nozzle to cool the plate entering the finishing mill and ensure the plate's initial rolling temperature.

[0066] The hot roughing mill inlet and outlet, the hot finishing mill 1 stand inlet and 4 stand outlet are all equipped with pyrometers to monitor the plate temperature in real time; the plate direction is: hot roughing mill, hot finishing mill 1 stand, hot finishing mill 2 stand, hot finishing mill 3 stand, hot finishing mill 4 stand;

[0067] (5) Finished product annealing: The cooled coil is sent to a box annealing furnace for two-stage annealing treatment. The furnace gas temperature for the first stage annealing treatment is 515℃ and the time is 5.55h; the furnace gas temperature for the second stage annealing treatment is 395℃ and the time is 2.8h, to obtain finished annealed aluminum alloy coil.

[0068] (6) Shearing: The finished annealed aluminum alloy coil is sheared to obtain a low-earing rate 6061-O state aluminum alloy sheet.

[0069]

[0070] As can be seen from the data in the table above, the method of this application adjusts and balances the texture type and strength of the finished product by optimizing the chemical composition of aluminum alloy, optimizing the hot rolling process, and optimizing the finished product annealing process, thereby achieving the purpose of reducing the ear-making rate.

[0071] Example 4

[0072] This embodiment is a method for preparing a low-ear-forming 6061-O state aluminum alloy sheet, which includes the following production process: including the following steps: (1) casting; (2) milling; (3) heating; (4) hot rolling; (5) finished product annealing; (6) shearing.

[0073] (1) Melting and casting: The raw materials are mixed according to the following mass percentages; the prepared raw materials are added to the melting furnace and mixed evenly to melt into liquid aluminum alloy to obtain aluminum alloy melt. The aluminum alloy melt is transferred to the holding furnace and refined at 750℃ for 50 minutes. The refined aluminum alloy melt is then cast into aluminum alloy ingots with a thickness of 620mm.

[0074]

[0075] (2) Milling: Mill the aluminum alloy ingot, with each large surface milled by 11mm / surface, and the side surfaces not milled, to obtain a milled aluminum alloy ingot.

[0076] (3) Heating: The milled aluminum alloy ingot is sent into a heating furnace and held at a heating temperature of 460°C for 24 hours to obtain a heat-treated aluminum alloy ingot.

[0077] (4) Hot continuous rolling: The heated aluminum alloy ingot is placed in a 1+4 hot continuous rolling process for hot continuous rolling. The equipment used in the process includes a 1-stand hot roughing mill and a 4-stand hot finishing mill. The ingot is rolled at a starting temperature of 460°C in the hot roughing mill. The hot roughing mill is rolled 23 times to obtain an intermediate billet with a thickness of 50 mm. The thickness of the intermediate billet is determined according to the thickness of the finished product. It is necessary to reserve a reduction of ≥85% to the thickness of the finished product. The temperature of the intermediate billet is controlled at 360°C. The intermediate billet is then transferred to the hot finishing mill and rolled to a thickness of 7 mm in a 4-stand hot finishing mill. The final rolling temperature is controlled at 220°C. The billet is then coiled and cooled off the line. The cooling method is to use a fan to cool both ends of the coil to obtain a cooled coil.

[0078] In the hot continuous rolling process, an emulsion is used for lubrication and cooling. The emulsion is used at a temperature of 65°C and the spraying system pressure is 6 bar. The cooling device is located on the inlet side of the finishing mill. The emulsion is sprayed onto the plate through a fan-shaped nozzle to cool the plate entering the finishing mill and ensure the plate's initial rolling temperature.

[0079] The hot roughing mill inlet and outlet, the hot finishing mill 1 stand inlet and 4 stand outlet are all equipped with pyrometers to monitor the plate temperature in real time; the plate direction is: hot roughing mill, hot finishing mill 1 stand, hot finishing mill 2 stand, hot finishing mill 3 stand, hot finishing mill 4 stand;

[0080] (5) Finished product annealing: The cooled coil is sent to a box annealing furnace for two-stage annealing treatment. The furnace gas temperature for the first stage annealing treatment is 525°C and the time is 6.5h; the furnace gas temperature for the second stage annealing treatment is 405°C and the time is 3.2h, to obtain finished annealed aluminum alloy coil.

[0081] (6) Shearing: The finished annealed aluminum alloy coil is sheared to obtain a low-earing rate 6061-O state aluminum alloy sheet.

[0082]

[0083] As can be seen from the data in the table above, the method of this application adjusts and balances the texture type and strength of the finished product by optimizing the chemical composition of aluminum alloy, optimizing the hot rolling process, and optimizing the finished product annealing process, thereby achieving the purpose of reducing the ear-making rate.

[0084] Comparative Example 1

[0085] This embodiment is a method for preparing a low-ear-forming 6061-O state aluminum alloy sheet, which includes the following production process: including the following steps: (1) casting; (2) milling; (3) heating; (4) hot rolling; (5) finished product annealing; (6) shearing.

[0086] (1) Melting and casting: The raw materials are mixed according to the following mass percentages; the prepared raw materials are added to the melting furnace and mixed evenly to melt into liquid aluminum alloy to obtain aluminum alloy melt. The aluminum alloy melt is transferred to the holding furnace and refined at 750℃ for 50 minutes. The refined aluminum alloy melt is then cast into aluminum alloy ingots with a thickness of 620mm.

[0087]

[0088]

[0089] (2) Milling: Mill the aluminum alloy ingot, with each large surface milled by 11mm / surface, and the side surfaces not milled, to obtain a milled aluminum alloy ingot.

[0090] (3) Heating: The milled aluminum alloy ingot is sent into a heating furnace and held at a heating temperature of 450°C for 8 hours to obtain a heat-treated aluminum alloy ingot.

[0091] (4) Hot continuous rolling: The heated aluminum alloy ingot is placed in a 1+4 hot continuous rolling process for hot continuous rolling. The equipment used in the process includes a 1-stand hot roughing mill and a 4-stand hot finishing mill. The ingot is rolled at a starting temperature of 490°C in the hot roughing mill and rolled in 21 passes to obtain an intermediate billet with a thickness of 32 mm. The temperature of the intermediate billet is controlled at 420°C. The intermediate billet is then transferred to the hot finishing mill and rolled to a thickness of 5.0 mm in a 4-stand hot finishing mill. The final rolling temperature is controlled at 310°C. The billet is then coiled and cooled offline. The cooling method is to use a fan to cool both ends of the coil to obtain a cooled coil.

[0092] In the hot continuous rolling process, an emulsion is used for lubrication and cooling. The emulsion is used at a temperature of 65°C and the spraying system pressure is 6 bar. The cooling device is located on the inlet side of the finishing mill. The emulsion is sprayed onto the plate through a fan-shaped nozzle to cool the plate entering the finishing mill and ensure the plate's initial rolling temperature.

[0093] The hot roughing mill inlet and outlet, the hot finishing mill 1 stand inlet and 4 stand outlet are all equipped with pyrometers to monitor the plate temperature in real time; the plate direction is: hot roughing mill, hot finishing mill 1 stand, hot finishing mill 2 stand, hot finishing mill 3 stand, hot finishing mill 4 stand;

[0094] (5) Finished product annealing: The cooled coil is sent to a box annealing furnace for two-stage annealing treatment. The furnace gas temperature for the first stage annealing treatment is 520°C and the time is 6 hours. The furnace gas temperature for the second stage annealing treatment is 400°C and the time is 3 hours, to obtain finished annealed aluminum alloy coil.

[0095] (6) Shearing: The finished annealed aluminum alloy coil is sheared to obtain a low-earing rate 6061-O state aluminum alloy sheet.

[0096]

[0097] As can be seen from the data in the table above, the method of this application adjusts and balances the texture type and strength of the finished product by optimizing the chemical composition of aluminum alloy, optimizing the hot rolling process, and optimizing the finished product annealing process, thereby achieving the purpose of reducing the ear-making rate.

[0098] Comparative Example 2

[0099] This embodiment is a method for preparing a low-ear-forming 6061-O state aluminum alloy sheet, which includes the following production process: including the following steps: (1) casting; (2) milling; (3) heating; (4) hot rolling; (5) finished product annealing; (6) shearing.

[0100] (1) Melting and casting: The raw materials are mixed according to the following mass percentages; the prepared raw materials are added to the melting furnace and mixed evenly to melt into liquid aluminum alloy to obtain aluminum alloy melt. The aluminum alloy melt is transferred to the holding furnace and refined at 750℃ for 50 minutes. The refined aluminum alloy melt is then cast into aluminum alloy ingots with a thickness of 620mm.

[0101]

[0102] (2) Milling: Mill the aluminum alloy ingot, with each large surface milled by 11mm / surface, and the side surfaces not milled, to obtain a milled aluminum alloy ingot.

[0103] (3) Heating: The milled aluminum alloy ingot is sent into a heating furnace and held at a heating temperature of 450°C for 8 hours to obtain a heat-treated aluminum alloy ingot.

[0104] (4) Hot continuous rolling: The heated aluminum alloy ingot is placed in a 1+4 hot continuous rolling process for hot continuous rolling. The equipment used in the process includes a 1-stand hot roughing mill and a 4-stand hot finishing mill. The ingot is rolled at a starting temperature of 510°C in the hot roughing mill and rolled in 21 passes to obtain an intermediate billet with a thickness of 34 mm. The temperature of the intermediate billet is controlled at 440°C. The intermediate billet is then transferred to the hot finishing mill and rolled to a thickness of 6.0 mm in a 4-stand hot finishing mill. The final rolling temperature is controlled at 330°C. The billet is then coiled and cooled offline. The cooling method is to use a fan to cool both ends of the coil to obtain a cooled coil.

[0105] In the hot continuous rolling process, an emulsion is used for lubrication and cooling. The emulsion is used at a temperature of 65°C and the spraying system pressure is 6 bar. The cooling device is located on the inlet side of the finishing mill. The emulsion is sprayed onto the plate through a fan-shaped nozzle to cool the plate entering the finishing mill and ensure the plate's initial rolling temperature.

[0106] The hot roughing mill inlet and outlet, the hot finishing mill 1 stand inlet and 4 stand outlet are all equipped with pyrometers to monitor the plate temperature in real time; the plate direction is: hot roughing mill, hot finishing mill 1 stand, hot finishing mill 2 stand, hot finishing mill 3 stand, hot finishing mill 4 stand;

[0107] (5) Finished product annealing: The cooled coil is sent to a box annealing furnace for two-stage annealing treatment. The furnace gas temperature for the first stage annealing treatment is 520°C and the time is 6 hours. The furnace gas temperature for the second stage annealing treatment is 400°C and the time is 3 hours, to obtain finished annealed aluminum alloy coil.

[0108] (6) Shearing: The finished annealed aluminum alloy coil is sheared to obtain a low-earing rate 6061-O state aluminum alloy sheet.

[0109]

[0110]

[0111] As can be seen from the data in the table above, the method of this application adjusts and balances the texture type and strength of the finished product by optimizing the chemical composition of aluminum alloy, optimizing the hot rolling process, and optimizing the finished product annealing process, thereby achieving the purpose of reducing the ear-making rate.

[0112] As can be seen from the experimental results of the above embodiments, the present invention provides a method for preparing a low-earing-rate 6061-O state aluminum alloy sheet. This invention achieves this by rationally controlling the chemical composition of the aluminum alloy, optimizing the hot continuous rolling process, and optimizing the finished product annealing process. It employs a lower initial hot roughing rolling temperature to reduce the proportion of the original cubic texture in the intermediate billet, controls the intermediate billet temperature below the recrystallization temperature, and reserves a reduction of ≥85% from the intermediate billet to the finished product. Through rapid cooling of the emulsion during the hot finishing rolling process, the sheet material exhibits no recrystallization behavior during hot finishing rolling, forming a hot-rolled billet with a predominantly rolled texture. Furthermore, the final rolling temperature of the hot finishing rolling is controlled at 190–220°C, which avoids the consumption of a large amount of rolled texture due to high-temperature self-annealing after the product is removed from the production line. Furthermore, the finished product annealing adopts a two-stage annealing process using a box-type annealing furnace, which efficiently and quickly reaches the annealing temperature, obtaining a balanced texture type and strength. The finished sheet has a low earing rate, fine and uniform grains, and excellent deep-drawing performance.

[0113] This invention discloses a method for preparing 6061-O state aluminum alloy sheet with low earing rate. The method optimizes the texture type and strength of the hot-rolled billet by designing aspects such as the initial rolling temperature, intermediate billet temperature, reduction allowance from intermediate billet to finished product, rolling passes, final rolling temperature of hot finishing, and management of lubrication and cooling media. Furthermore, finished product annealing is used to control texture balance, solving the current industry problem of high earing rate in the 0° / 90° direction of hot-rolled billets. This provides a new approach and direction for further reducing overall production costs in the aluminum processing industry. By using hot-rolled billets and finished product annealing to prepare sheet with low earing rate, the cold rolling process is reduced, processing time is shortened, overall processing efficiency is improved, the overall order production cycle is shortened, overall production costs are reduced, and product market competitiveness is enhanced.

[0114] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a low-ear-forming 6061-O state aluminum alloy sheet, characterized in that, The method includes the following steps: (1) melting and casting; (2) milling; (3) heating; (4) hot continuous rolling; (5) finished product annealing; (6) shearing; In step (1), the mass percentage of the aluminum alloy chemical composition is as follows: Si: 0.4-0.8%, Fe: ≤0.7%, Cu: 0.15-0.4%, Mn: ≤0.15%, Mg: 0.8-1.2%, Cr: 0.04-0.35%, Zn: ≤0.25%, Ti: ≤0.15%, other impurity elements ≤0.05% each, other impurity elements total ≤0.15%, and the balance is Al, totaling 100%. In step (1), the prepared raw materials are added to the melting furnace and mixed evenly to melt into liquid aluminum alloy to obtain aluminum alloy melt. The aluminum alloy melt is transferred to the holding furnace and refined at 720-750℃ for 30-50 minutes. The refined aluminum alloy melt is then cast into aluminum alloy ingots with a thickness of 400-620mm. In step (3), the heating temperature is 400-460℃ and the holding time is 3-24h; In step (4), hot rolling is carried out in the 1+4 hot continuous rolling process. The equipment used in the process includes a 1-stand hot roughing mill and a 4-stand hot finishing mill. The ingot is rolled at a starting temperature of 400-460°C in the hot roughing mill. The hot roughing mill is rolled 17-23 times to obtain an intermediate billet with a thickness of 20-50 mm. The temperature of the intermediate billet is controlled at 320-360°C. The intermediate billet is then transferred to the hot finishing mill and rolled to a thickness of 2.5-7 mm in the hot finishing mill with 4 stands. The final rolling temperature is controlled at 190-220°C. The billet is then coiled and cooled off the line. In step (4), the thickness of the intermediate billet is determined according to the thickness of the finished product, wherein the thickness of the intermediate billet is obtained by a reduction of more than 85% to obtain the thickness of the finished product; In step (5), the roll material is sent to a box-type annealing furnace for two-stage annealing treatment. The furnace gas temperature for the first stage of annealing treatment is 515-525℃ and the time is 5.5-6.5h. The furnace gas temperature for the second stage of annealing treatment is 395-405℃ and the time is 2.8-3.2h.

2. The method for preparing a low-ear-forming 6061-O state aluminum alloy sheet according to claim 1, characterized in that, In step (1), the mass percentage of the aluminum alloy chemical composition is as follows: Si: 0.5-0.8%, Fe: ≤0.7%, Cu: 0.18-0.4%, Mn: ≤0.15%, Mg: 0.9-1.2%, Cr: 0.07-0.35%, Zn: ≤0.25%, Ti: ≤0.15%, other impurity elements ≤0.05% individually, other impurity elements ≤0.15% in total, and the balance is Al, totaling 100%.

3. The method for preparing a low-ear-forming 6061-O state aluminum alloy sheet according to claim 1, characterized in that, In step (2), the aluminum alloy ingot is milled, with each large surface milled by 9 to 11 mm, and the side surfaces are not milled.

4. The method for preparing a low-ear-forming 6061-O state aluminum alloy sheet according to claim 1, characterized in that, In step (3), the heating temperature is 420-460℃ and the heat preservation time is 6-24h.

5. The method for preparing a low-ear-forming 6061-O state aluminum alloy sheet according to claim 1, characterized in that, In step (4), the hot rolling process uses an emulsion for lubrication and cooling. The temperature of the emulsion during use is 50-65°C, and the pressure of the spraying system is 4-6 bar. The cooling device is located on the inlet side of the finishing mill. The emulsion is sprayed onto the plate through a fan-shaped nozzle to cool the plate entering the finishing mill to ensure the initial rolling temperature of the plate.

6. The method for preparing a low-ear-forming 6061-O state aluminum alloy sheet according to claim 5, characterized in that, In step (4), the hot roughing mill inlet and outlet, the hot finishing mill 1 stand inlet and 4 stand outlet are all equipped with pyrometers to monitor the temperature of the plate in real time.

7. The method for preparing a low-ear-forming 6061-O state aluminum alloy sheet according to claim 1, characterized in that, In step (4), the cooling method after unloading is to use a fan to cool both ends of the roll material.

8. The method for preparing a low-ear-forming 6061-O state aluminum alloy sheet according to claim 1, characterized in that, In step (5), the roll material is sent to a box-type annealing furnace for two-stage annealing treatment. The furnace gas temperature for the first stage of annealing treatment is 520-525℃ and the time is 6-6.5h. The furnace gas temperature for the second stage of annealing treatment is 400-405℃ and the time is 3-3.2h.

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