Multi-stage fusion casting purification and asymmetrical rolling integrated process for aluminum alloy sheet

Abstract

The invention discloses a multi-stage casting purification and asynchronous rolling integrated process of an aluminum alloy sheet, which comprises the steps of multi-stage casting purification, asynchronous hot rolling, high-processing-rate cold rolling, low last-pass reduction rate and optimized intermediate annealing, specifically, the casting purification adopts mixed refining of a sodium-free refining agent and argon, online degassing and two-stage filtering; the high purity of the melt is ensured; the asynchronous hot rolling adopts a pass distribution mode of front-section large reduction and rear-section small reduction; the total machining rate of cold rolling is 71%-80%, and the reduction rate of the last pass is smaller than or equal to 15%; and the intermediate annealing adopts a three-section temperature control process. The method effectively solves the problems of low melt purity, high plate anisotropy and poor surface quality in the traditional process, and realizes green and efficient production of the aluminum alloy thin plate with low earing rate (less than or equal to 5%) and high surface quality.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy sheet processing technology, specifically to an integrated process of multi-stage melting and casting purification and asynchronous rolling of aluminum alloy thin sheets. Background Technology

[0002] High-end aluminum sheets are widely used in cosmetic containers, electronic casings, and other fields, but they require extremely high purity, uniformity of microstructure, anisotropy, and surface quality. However, traditional processes for producing high-end aluminum sheets have many shortcomings:

[0003] In the melt purification process, traditional processes often use chlorine- and sodium-containing refining agents, which are not only environmentally unfriendly and prone to causing pollution, but also easily leave residues in the molten aluminum, leading to defects such as porosity and inclusions in the sheet material.

[0004] An unreasonable rolling process design results in significant anisotropy of the sheet metal during subsequent processing, leading to a high ear-forming rate and affecting the forming accuracy and appearance quality of the product.

[0005] The lack of effective coordination between heat treatment and rolling processes makes it difficult to accurately control the grain structure of the sheet material, resulting in insufficient product performance stability.

[0006] The aforementioned defects often necessitate subsequent mechanical polishing processes to compensate for surface quality issues in the final product. This not only increases production costs but also causes environmental pollution from polishing dust and wastes resources, failing to meet the demands of high-end sectors for green, efficient, and high-quality production of aluminum alloy thin sheets. Therefore, developing an aluminum alloy thin sheet manufacturing process that integrates high-purity melt control, asynchronous hot rolling microstructure regulation, cold rolling deformation optimization, and intermediate annealing has become an urgent technical problem to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to solve the problems of poor environmental performance, high anisotropy, and insufficient surface quality in the existing technology, and to provide an integrated process of multi-stage melting and casting purification and asynchronous rolling of aluminum alloy thin plates. Through systematic process design and optimization, aluminum alloy thin plates with high internal quality, low anisotropy, and good surface quality are produced, which are suitable for high-end fields, while reducing the environmental pressure and production costs in the production process.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] The integrated process of multi-stage melting, casting purification, and asynchronous rolling of aluminum alloy thin sheets includes the following steps:

[0010] S1 Multi-stage Melting and Casting Purification

[0011] (1) Refining is carried out by mixing argon gas with sodium-free refining agent;

[0012] (2) The refined melt is passed into an online degassing box for purification treatment;

[0013] (3) The degassed melt is filtered sequentially through a two-stage plate filter to remove inclusions in the melt;

[0014] S2 rolling and heat treatment synergy

[0015] (1) Asynchronous hot rolling: Hot rolling is carried out in 21 passes, and the final rolling temperature is controlled at 280-300℃;

[0016] (2) Cold rolling treatment: Two cold rolling treatments are adopted, and the reduction rate of the last pass is ≤15%;

[0017] (3) Intermediate annealing: An intermediate annealing system with three-stage temperature control is adopted between two cold rolling processes.

[0018] Furthermore, in S1 (1), the amount of sodium-free refining agent added is 0.6-0.8 kg / 1000 kg of aluminum liquid.

[0019] Furthermore, in S1 (2), the rotor speed in the degassing box is controlled at 350-380 r / min, so that the hydrogen content of the melt is ≤0.15 ml / 100 g Al.

[0020] Furthermore, in S1 (3), the primary filter specification is 40ppi and the secondary filter specification is 60ppi.

[0021] Furthermore, in S2 (1), the first 15 passes use large reduction rolling, with a reduction of >35mm per pass, and the last 6 passes use small reduction rolling, with a reduction of <15mm per pass to control the plate shape.

[0022] Furthermore, in S2 (2), the total cold rolling processing rate is controlled at 71%-80%.

[0023] Furthermore, in S2 (3), the three-stage intermediate annealing process is as follows: preheating at 240℃±5℃ for 1.5-2h; heating at 380℃±5℃; and holding at 345℃±5℃ for 2-3h.

[0024] The system for performing the above-mentioned integrated multi-stage casting purification and asynchronous rolling process for aluminum alloy thin plates includes:

[0025] The smelting furnace is equipped with a sodium-free refining agent feeding device;

[0026] The online degassing box has an adjustable rotor speed range of 350-380 r / min.

[0027] A two-stage plate filter system, consisting of a primary 40ppi filter plate and a secondary 60ppi filter plate;

[0028] Asynchronous hot rolling mills can achieve multi-pass asynchronous rolling;

[0029] Cold rolling mills can control the total processing rate and the final pass reduction rate;

[0030] The annealing furnace is capable of performing a three-stage temperature-controlled annealing process.

[0031] An aluminum alloy sheet is prepared by the multi-stage melting, casting, purification and asynchronous rolling integrated process of the aluminum alloy sheet described above. The alloy sheet has an earing rate of ≤5%, a tensile strength of ≥175MPa and an elongation of ≥4%.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: The integrated process of multi-stage melting and casting purification and asynchronous rolling of this aluminum alloy sheet has the following advantages:

[0033] 1. Environmental protection and high purity: This invention uses a sodium-free refining agent mixed with argon gas for refining, avoiding the environmental pollution caused by traditional chlorine- and sodium-containing refining agents, making it green and environmentally friendly; at the same time, through a multi-stage melting and casting purification process, the hydrogen content of the melt is ≤0.15ml / 100gAl, the inclusion content is significantly reduced, and the internal quality of the plate is effectively improved.

[0034] 2. Significantly improves anisotropy: Through the asynchronous hot rolling mode of high-temperature and high-reduction rolling in the front stage and low-temperature and low-reduction shaping in the back stage, combined with the cold rolling process with low final pass reduction rate, the ear-making rate of the sheet is stably controlled below 5%, which greatly improves the anisotropy of the sheet and enhances the forming accuracy of the product.

[0035] 3. Improved surface quality and environmental benefits: Through process synergy optimization, this invention enables products to directly obtain a high-gloss, uniformly colored surface after anodizing. Downstream customers can significantly reduce or even eliminate the mechanical polishing process, which not only reduces production costs but also reduces the pollution of polishing dust to the environment and improves the working environment.

[0036] 4. Strong process versatility: The core technology of this invention can be extended to the production of other high-performance aluminum alloy thin plates, with a wide range of applications and good prospects for industrial application. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] This invention includes a first aspect: an integrated process for multi-stage casting purification and asynchronous rolling of aluminum alloy thin plates, comprising the following steps:

[0039] S1 Multi-stage Melting and Casting Purification

[0040] (1) Argon gas and sodium-free refining agent are mixed for refining. The amount of sodium-free refining agent added is 0.6-0.8 kg / 1000 kg of aluminum liquid;

[0041] (2) The refined melt is passed into an online degassing box for purification. The rotor speed in the degassing box is controlled at 350-380 r / min so that the hydrogen content of the melt is ≤0.15 ml / 100 g Al;

[0042] (3) The degassed melt is filtered sequentially through a two-stage plate filter. The first-stage filter has a specification of 40ppi, and the second-stage filter has a specification of 60ppi to remove inclusions in the melt.

[0043] S2 rolling and heat treatment synergy

[0044] (1) Asynchronous hot rolling: Hot rolling is carried out in 21 passes. The first 15 passes are rolled with a large reduction, with a reduction of >35mm per pass. The last 6 passes are rolled with a small reduction, with a reduction of <15mm per pass to control the plate shape. The final rolling temperature is controlled at 280-300℃.

[0045] (2) Cold rolling treatment: Two cold rolling treatments are adopted, the total cold rolling processing rate is controlled at 71%-80%, and the final reduction rate is ≤15%;

[0046] (3) Intermediate annealing: Between the two cold rolling processes, a three-stage temperature-controlled intermediate annealing system is adopted. The three-stage intermediate annealing system is as follows: preheating at 240℃±5℃ for 1.5-2h; heating at 380℃±5℃; and holding at 345℃±5℃ for 2-3h.

[0047] The present invention includes a second aspect, a system for performing the above-described integrated process of multi-stage casting purification and asynchronous rolling of aluminum alloy thin plates, comprising:

[0048] The smelting furnace is equipped with a sodium-free refining agent feeding device;

[0049] The online degassing box has an adjustable rotor speed range of 350-380 r / min.

[0050] A two-stage plate filter system, consisting of a primary 40ppi filter plate and a secondary 60ppi filter plate;

[0051] Asynchronous hot rolling mills can achieve multi-pass asynchronous rolling;

[0052] Cold rolling mills can control the total processing rate and the final pass reduction rate;

[0053] The annealing furnace is capable of performing a three-stage temperature-controlled annealing process.

[0054] The present invention includes a third aspect, an aluminum alloy sheet, which is prepared by the multi-stage melting and casting purification and asynchronous rolling integrated process of the aluminum alloy sheet described above, wherein the alloy sheet has an earing rate of ≤5%, a tensile strength of ≥175MPa, and an elongation of ≥4%.

[0055] Example 1

[0056] Taking the production of 0.4mm thick 5657H16 sheet metal for cosmetic container caps as an example, the specific implementation steps are as follows:

[0057] (1) Add 0.75 kg of sodium-free refining agent per 1000 kg of aluminum liquid to the aluminum liquid in proportion, and pass argon gas through for mixing and refining;

[0058] (2) The refined melt is fed into an online degassing box. The rotor speed in the degassing box is controlled at 365 r / min to degas the melt and ensure that the hydrogen content of the melt is ≤0.15 ml / 100 g Al.

[0059] (3) The degassed melt is passed through a 40ppi primary plate filter and a 60ppi secondary plate filter in sequence to remove inclusions in the melt.

[0060] (4) Cast the filtered melt to obtain an ingot, and then homogenize the ingot.

[0061] (5) The homogenized ingot is subjected to asynchronous hot rolling in 21 passes. The reduction of each pass in the first 15 passes is >35mm, and the reduction of each pass in the last 6 passes is <15mm. The final rolling temperature is controlled at 285℃, and the thickness is hot rolled to 7.0mm.

[0062] (6) The hot-rolled sheet is cold-rolled once to a thickness of 2.0 mm;

[0063] (7) Perform a three-stage intermediate annealing process, with an annealing regime of 240℃×2h->380℃->350℃×3h;

[0064] (8) The annealed sheet is subjected to secondary cold rolling, with the final reduction rate controlled at 13%, and finally cold rolled to a thickness of 0.4 mm to obtain a 5657H16 aluminum alloy sheet.

[0065] The aluminum alloy sheet produced in this embodiment has a tensile strength ≥175MPa, an elongation ≥4%, and an ear-making rate ≤5%. After anodizing, it can directly obtain a high-gloss, uniformly colored surface without the need for subsequent mechanical polishing.

[0066] Example 2

[0067] Taking a 0.8mm thick 5052H32 tempered sheet metal as an example for manufacturing electronic device housings, the specific implementation steps are as follows:

[0068] (1) Add 0.65 kg of sodium-free refining agent per 1000 kg of aluminum liquid to the aluminum liquid in proportion, and pass argon gas through to mix and refine, ensuring that the refining agent and aluminum liquid are fully in contact and react;

[0069] (2) The refined melt is fed into an online degassing box. The rotor speed in the degassing box is controlled at 355 r / min to degas the melt. The hydrogen content of the melt is detected to be 0.13 ml / 100 g Al, which meets the requirement of ≤0.15 ml / 100 g Al.

[0070] (3) The degassed melt is passed through a 40ppi primary plate filter and a 60ppi secondary plate filter in sequence. The removal rate of inclusions with a size ≥10μm in the melt after filtration is over 98%.

[0071] (4) The filtered melt was semi-continuously cast to obtain an ingot with a thickness of 400 mm. Then, it was homogenized at 480℃±5℃ for 6 hours to eliminate the component segregation inside the ingot.

[0072] (5) The homogenized ingot is subjected to asynchronous hot rolling in 21 passes. The reduction of each pass in the first 15 passes is controlled at 36-38 mm, and the reduction of each pass in the last 6 passes is controlled at 12-14 mm. The final rolling temperature is controlled at 290℃, and the hot rolled coil is rolled to a thickness of 10.0 mm.

[0073] (6) Perform the first cold rolling on the hot-rolled coil, with the cold rolling rate controlled at 55%, and cold-roll to a thickness of 4.5 mm;

[0074] (7) Perform three-stage intermediate annealing treatment. The annealing regime is 245℃×2h->375℃->345℃×2.5h. After annealing, the hardness of the plate is controlled at 60-65HB.

[0075] (8) The annealed sheet is subjected to a second cold rolling process. The reduction rate of the last pass is controlled at 14%, the total cold rolling processing rate is 75%, and the final cold rolling is carried out to a thickness of 0.8 mm to obtain a 5052H32 state aluminum alloy sheet.

[0076] The aluminum alloy sheet produced in this embodiment has a tensile strength ≥210MPa, elongation ≥8%, and yield strength ≥180MPa. It has excellent formability and corrosion resistance, and can meet the stringent requirements of electronic device housings for sheet strength and appearance.

[0077] Example 3

[0078] Taking the production of 0.3mm thick 3003H14 sheet metal for food packaging caps as an example, the specific implementation steps are as follows:

[0079] (1) Add 0.70 kg / 1000 kg of sodium-free refining agent to the aluminum liquid according to the ratio, and mix and refine with argon gas. The refining time is controlled within 15 minutes to ensure the refining effect.

[0080] (2) The refined melt is fed into an online degassing box. The rotor speed in the degassing box is controlled at 370 r / min. After degassing, the hydrogen content of the melt is measured to be 0.12 ml / 100 g Al, which meets the requirement of ≤0.15 ml / 100 g Al.

[0081] (3) The degassed melt passes through a 40ppi primary plate filter and a 60ppi secondary plate filter in sequence to effectively intercept oxide inclusions and non-metallic impurities in the melt.

[0082] (4) Cast the filtered melt into an ingot with a thickness of 350 mm, and homogenize it at 450℃±5℃ for 5 hours to refine the grain structure of the ingot.

[0083] (5) The homogenized ingot is subjected to asynchronous hot rolling in 21 passes. The reduction of each pass in the first 15 passes is 35-37 mm, and the reduction of each pass in the last 6 passes is 10-13 mm. The final rolling temperature is controlled at 285℃, and the thickness is hot rolled to 8.0 mm.

[0084] (6) The hot-rolled sheet is subjected to a first cold rolling process with a cold rolling rate of 62.5% to a thickness of 3.0 mm;

[0085] (7) Three-stage intermediate annealing treatment was carried out. The annealing regime was 235℃×2h->380℃->350℃×2h. After annealing, the plate exhibited good plasticity.

[0086] (8) The annealed sheet is subjected to a second cold rolling, with the final reduction rate controlled at 12% and the total cold rolling rate at 78%. Finally, it is cold rolled to a thickness of 0.3 mm to obtain a 3003H14 state aluminum alloy sheet.

[0087] The aluminum alloy sheet produced in this embodiment has been tested and found to have a tensile strength ≥180MPa, elongation ≥6%, ear-making rate ≤4%, high surface finish, and meets the safety standards for food contact materials. It is suitable for stamping and forming production of food packaging caps.

[0088] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An integrated process for multi-stage melting, casting purification, and asynchronous rolling of aluminum alloy thin plates, characterized in that, Includes the following steps: S1 Multi-stage Melting and Casting Purification (1) Refining is carried out by mixing argon gas with sodium-free refining agent; (2) The refined melt is passed into an online degassing box for purification treatment; (3) The degassed melt is filtered sequentially through a two-stage plate filter to remove inclusions in the melt; S2 rolling and heat treatment synergy (1) Asynchronous hot rolling: Hot rolling is carried out in 21 passes, and the final rolling temperature is controlled at 280-300℃; (2) Cold rolling treatment: Two cold rolling treatments are adopted, and the reduction rate of the last pass is ≤15%; (3) Intermediate annealing: An intermediate annealing system with three-stage temperature control is adopted between two cold rolling processes.

2. The integrated process of multi-stage casting purification and asynchronous rolling of aluminum alloy thin plates according to claim 1, characterized in that, In S1 (1), the amount of sodium-free refining agent added is 0.6-0.8 kg / 1000 kg of aluminum liquid.

3. The integrated process of multi-stage casting purification and asynchronous rolling of aluminum alloy thin plates according to claim 1, characterized in that, In S1 (2), the rotor speed in the degassing box is controlled at 350-380 r / min so that the hydrogen content of the melt is ≤0.15 ml / 100 g Al.

4. The integrated process of multi-stage casting purification and asynchronous rolling of aluminum alloy thin plates according to claim 1, characterized in that, In S1 (3), the primary filter specification is 40ppi, and the secondary filter specification is 60ppi.

5. The integrated process of multi-stage casting purification and asynchronous rolling of aluminum alloy thin plates according to claim 1, characterized in that, In S2 (1), the first 15 passes are rolled with a large reduction amount, with a reduction amount of >35mm per pass, and the last 6 passes are rolled with a small reduction amount, with a reduction amount of <15mm per pass, in order to control the shape of the plate.

6. The integrated process of multi-stage casting purification and asynchronous rolling of aluminum alloy thin plates according to claim 1, characterized in that, In S2 (2), the total cold rolling processing rate is controlled at 71%-80%.

7. The integrated process of multi-stage casting purification and asynchronous rolling of aluminum alloy thin plates according to claim 1, characterized in that, In S2 (3), the three-stage intermediate annealing process is as follows: preheating at 240℃±5℃ for 1.5-2h; heating at 380℃±5℃; and holding at 345℃±5℃ for 2-3h.

8. A system for performing the integrated multi-stage casting purification and asynchronous rolling process for aluminum alloy thin plates as described in any one of claims 1-7, characterized in that, include: The smelting furnace is equipped with a sodium-free refining agent feeding device; The online degassing box has an adjustable rotor speed range of 350-380 r / min. A two-stage plate filter system, consisting of a primary 40ppi filter plate and a secondary 60ppi filter plate; Asynchronous hot rolling mills can achieve multi-pass asynchronous rolling; Cold rolling mills can control the total processing rate and the final pass reduction rate; The annealing furnace is capable of performing a three-stage temperature-controlled annealing process.

9. An aluminum alloy sheet, prepared by an integrated multi-stage melting, casting, purification, and asynchronous rolling process according to any one of claims 1-7, characterized in that, The ear-making rate of alloy sheet is ≤5%, the tensile strength is ≥175MPa, and the elongation is ≥4%.