A kind of aluminum alloy ultra-thin sheet coil material produced by continuous extrusion and rolling and preparation method thereof

Abstract

The present invention relates to the technical field of aluminum alloy sheet preparation, and in particular to a continuous extrusion and rolling aluminum alloy ultra-thin sheet coil and a preparation method thereof, comprising the following steps: S1, pre-treating recycled aluminum alloy waste; S2, heating and melting the pre-treated aluminum alloy waste and raw pure aluminum ingots to obtain an initial alloy liquid; S3, adding a composite refining agent to the initial alloy liquid for refining to obtain a refined alloy liquid; S4, casting the refined alloy liquid into short bars; S5, preheating and extruding the short bars to make aluminum alloy sheets; S6, pressing and coiling the aluminum alloy sheets to obtain an aluminum alloy ultra-thin sheet coil. The technical solution of the present invention realizes the efficient reuse of aluminum alloy waste and the preparation of high-quality ultra-thin sheets, and can effectively improve the mechanical properties of ultra-thin sheet coils prepared from aluminum alloy waste.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy sheet preparation, and in particular to a continuously extruded and rolled aluminum alloy ultra-thin sheet coil and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of the automobile industry and the improvement of environmental protection requirements, the demand for aluminum alloys and the demand for recycling have continued to increase. In the aluminum processing industry, ultra-thin sheet coils are an important product form, and their preparation process has high requirements for raw material purity and performance. At present, the use of recycled aluminum alloy waste to prepare aluminum alloy sheets mainly faces the following problems: First, there is an important problem in the production process of waste aluminum recycling: almost every reuse of waste aluminum requires remelting, and the remelting process will cause different degrees of iron increase. Impure iron is difficult to be purified and removed, so that Fe elements are enriched in aluminum, and thus accumulate to a very high content during the recycling of waste aluminum. The solid solubility of iron in aluminum is very low, and the iron-rich phase is more likely to appear in the aluminum alloy structure in the form of needle-shaped β (Al5FeSi). This phase is coarse and flake-shaped in three dimensions, which is both hard and brittle, forming a stress concentration source, seriously splitting the aluminum matrix, and reducing the mechanical properties of the aluminum alloy. The presence of iron impurities will also destroy the continuity of the aluminum oxide film on the aluminum surface, forming a small anode and a large cathode on the aluminum alloy surface, thereby reducing the corrosion resistance of the aluminum alloy and making the surface quality of the aluminum alloy after anodizing worse. Secondly, the recycled aluminum alloy waste (mainly including the edge materials, waste materials and scrapped parts generated in the process of preparing aluminum alloy) contains a high content of oxide impurities, and the surface is generally attached with cutting fluids, lubricating oils and other oil substances, and some also have electroplating coatings.

[0003] The existing patent CN201510688021.1 discloses an aluminum alloy refining agent containing rare earth, including the following raw materials by weight: 70-80 parts of NaCl, 50-56 parts of KCl, 10-15 parts of MgCl2, 5-8 parts of LiCl, 0-36 parts of NaF3, 10-12 parts of AlF3, 10-12 parts of sodium fluoroaluminate, 5-10 parts of carbon powder, 25-35 parts of light calcium carbonate, 10-15 parts of marble powder, 8-12 parts of CaO, 2-5 parts of fluorite, and 5-10 parts of rare earth. The aluminum alloy refining agent prepared by the above scheme can not only obtain a good dehydrogenation effect, but also has a good modification effect on the aluminum alloy melt, which can significantly reduce the grain size and improve the uniformity of aluminum products. However, although the above refining agent scheme can reduce the grain size to a certain extent, it only uses rare earth elements as modifiers, and the modification reaction efficiency between rare earth and molten aluminum is low, resulting in limited grain refinement effect. At the same time, this scheme is mainly used for dehydrogenation and modification processing of conventional aluminum alloy ingots, and is not optimized for the special precision requirements in ultra-thin plate processing. Summary of the invention

[0004] In view of this, in order to solve the above technical problems, the present invention proposes a continuously extruded and rolled aluminum alloy ultra-thin sheet coil and a preparation method thereof.

[0005] The technical solution of the present invention is implemented as follows: The present invention provides a continuous extrusion and rolling aluminum alloy ultra-thin sheet coil and a preparation method thereof, comprising the following steps:

[0006] S1. Pre-treating the recycled aluminum alloy waste to obtain pre-treated aluminum alloy waste, wherein the recycled aluminum alloy waste is cutting aluminum waste collected from a factory workshop, and the aluminum content in the recycled aluminum alloy waste is more than 90%;

[0007] S2, heating and melting the pretreated aluminum alloy waste and the raw material pure aluminum ingot according to the mass ratio, the melting temperature in the furnace is 730-750° C., after the raw materials in the furnace are melted, removing the slag to obtain an initial alloy liquid;

[0008] S3, adding a composite refining agent to the initial alloy liquid for refining at a refining temperature of 720-740°C for a refining time of 40-60 min, slagging and furnace conduction after refining, standing in a standing furnace for 20-30 min, filtering and degassing after standing to obtain a refined alloy liquid;

[0009] S4, casting the refined alloy liquid into aluminum alloy casting rods at a casting temperature of 695-715° C., with the diameter of the casting rods matching that of the extruder, and cutting the casting rods into short rods for extrusion;

[0010] S5, preheating the short bar to 480-500°C for extrusion to form an aluminum alloy plate;

[0011] S6. Pressing and coiling the aluminum alloy sheet to obtain an aluminum alloy ultra-thin sheet coil.

[0012] In the present invention, the cost of aluminum waste is lower than that of primary aluminum ingots. Through recycling and reuse, it can effectively realize the recycling of aluminum resources, reduce dependence on primary aluminum ingots, and reduce mineral mining and energy consumption. Through waste pretreatment and the introduction of composite refining agents, the problem of impurity enrichment (such as Fe and oxides) in waste is effectively solved, the formation of needle-shaped β (Al5FeSi) phase is inhibited, and the mechanical properties and corrosion resistance of aluminum alloy are significantly improved; by optimizing the extrusion and rolling process, the thickness uniformity and surface quality of ultra-thin sheet coils are ensured.

[0013] On the basis of the above technical solution, preferably, step S1 specifically includes:

[0014] S11, crushing the recycled aluminum alloy waste to obtain fragments;

[0015] S12. Place the scraps in a cleaning agent and perform ultrasonic cleaning at a temperature of 45-55°C, an ultrasonic power of 800-1000W, and a cleaning time of 15-20min. After the cleaning is completed, wash with water and dry to obtain pretreated aluminum alloy scrap.

[0016] On the basis of the above technical scheme, preferably, the aluminum alloy waste is cut aluminum waste collected from factory workshops, mainly Al-Si alloy, including aluminum chips and aluminum blocks. The surface of the aluminum alloy waste contains oxide impurities, and its surface is also covered with oil substances, emulsions and electroplating coatings.

[0017] On the basis of the above technical scheme, preferably, the composition of the cleaning agent includes 10-15wt% of sodium metasilicate pentahydrate, 3-5wt% of trisodium citrate, 3-5wt% of triethanolamine oleate, 5-8wt% of alcohol ether phosphate and 8-12wt% of isopropanol, and the balance is water.

[0018] In the present invention, considering the presence of impurities such as oxides, oily substances, emulsions and electroplating coatings on the surface of recycled aluminum alloy waste, the removal effect of impurities will affect the effects of subsequent smelting and refining processes. Based on this, the present invention first increases the specific surface area of ​​the waste by crushing treatment, thereby improving the efficiency of the subsequent cleaning process; then, by introducing a cleaning agent, the alkaline environment provided by sodium metasilicate pentahydrate in the cleaning agent synergizes with the surfactant system to enhance the emulsification effect on oil stains; the chelating effect of trisodium citrate and the decontamination effect of the surfactant promote each other, thereby improving the removal efficiency of metal oxides; the presence of isopropanol not only enhances the effect of the surfactant, but also promotes the drying process after cleaning, thereby reducing the formation of water stains. The efficient pretreatment process lays the foundation for subsequent smelting and refining processes. By removing surface pollutants and oxides, the formation of inclusions during the smelting process is significantly reduced, the amount of refining agent used is reduced, and the quality of the final product is improved.

[0019] On the basis of the above technical solution, preferably, the added mass of the composite refining agent is 0.1-0.15wt% of the mass of the aluminum alloy.

[0020] On the basis of the above technical scheme, preferably, in step S3, the composite refining agent includes the following chemical composition: NaCl: 25-28wt%, Na3AlF6: 18-22wt%, Al-10Nb: 10-12wt%, ScF3: 5-7wt%, CeO2: 8-10wt%, Al2Cu: 8-10wt%, MnCl2: 6-8wt%.

[0021] On the basis of the above technical scheme, preferably, the preparation method of the refining agent includes: weighing NaCl, Na3AlF6, Al-10Nb, and Al2Cu in proportion, mixing, stirring evenly, heating to melt, and then cooling and crushing the mixture into particles to obtain a premix; mixing the premix with MnCl2, ScF3, CeO2 and polyethylene glycol evenly, pressing into blocks to obtain a refining agent.

[0022] On the basis of the above technical solution, preferably, the amount of polyethylene glycol added is 2-3wt% of the total mass of the composite refining agent.

[0023] In the present invention, firstly, Al-10Nb and ScF3 constitute a Fe phase control and grain optimization system. Al-10Nb inhibits the formation of needle-shaped β(Al5FeSi) phase and promotes the formation of rounded α(Al 12 The formation of Fe3Si) phase, while ScF3, with its negative thermal expansion characteristics, can improve the dispersion effect of the refining agent while refining the grains, further optimize the melt structure, and enhance the capture and removal of inclusions through F ions. Secondly, CeO2 decomposes stubborn impurities such as carbides through its excellent redox properties. At the same time, the addition of Al2Cu improves the melt fluidity and enhances the dispersion efficiency of CeO2. The intermetallic compound formed by the two further enhances the adsorption and removal effect of impurities. The synergistic effect of ScF3 and MnCl2 exerts the dual chemical conversion effect of chloride and fluoride. Among them, chloride can remove the oxide layer and passivation coating, and fluoride accelerates the desorption of coating and inclusions through its unique cracking effect. The negative thermal expansion effect of ScF3 increases the contact area of ​​the melt and strengthens the treatment efficiency.

[0024] On the basis of the above technical scheme, preferably, step S5 specifically includes: preheating the short bar material in sections to 490±10°C, extruding, the extrusion temperature is 470-480°C, the extrusion ratio is 25-35:1, the extrusion speed is 2-4mm / s, the discharge temperature is 440-460°C, and the aluminum alloy plate is made.

[0025] On the basis of the above technical scheme, preferably, in step S5, the segmented preheating specifically includes: heating the short bar material from room temperature to 380-400°C at a rate of ≤50°C / h, and keeping it warm for 3-4h; then continuing to heat it to 400-450°C at a rate of ≤40°C / h, and keeping it warm for 4-5h; finally, heating it to 480-500°C at a rate of ≤30°C / h, and keeping it warm for 5-6h.

[0026] The preheating stage adopts segmented preheating. The preheating in the low-temperature stage promotes the stabilization of the partial analyzed phase, gradually decomposes the residual impurities, releases the local stress of the inclusions and improves the microstructure of the alloy matrix; the medium-temperature stage strengthens the segregation and the uniform distribution of the second phase, activates the recrystallization mechanism of the aluminum matrix, and avoids premature softening that affects subsequent processes; the high-temperature stage further promotes the full dissolution of the precipitated phase and improves the homogeneity and plastic deformation capacity of the aluminum scrap.

[0027] Based on the above technical solution, preferably, step S6 specifically includes:

[0028] S61, performing 25-28 initial rolling of the aluminum alloy plate to form an intermediate plate with a thickness of 1.5-2.0 mm, with the initial rolling temperature being 480-490° C.;

[0029] S62, intermediate annealing is performed after initial rolling, the annealing temperature is controlled at 360-400°C, and the holding time is 1-2h;

[0030] S63, after intermediate annealing, 6-8 passes of finishing rolling are performed to roll into an intermediate plate with a thickness of mm, and the finishing rolling temperature is 330-350°C;

[0031] S64, after fine rolling, coiling is performed to obtain an aluminum alloy ultra-thin sheet coil.

[0032] In the present invention, the initial rolling stage is carried out through multiple passes of gradual thinning to effectively avoid the generation of defects such as cracks and delamination during the processing process, thereby ensuring the dimensional accuracy and surface quality of the plate; the intermediate annealing fully releases the residual stress introduced during the rolling process, promotes the recrystallization and homogenization of the structure, and improves the plasticity and toughness of the material; the low-temperature finishing rolling can effectively control the grain growth, refine the organizational structure, and improve the strength and surface quality of the plate.

[0033] The present invention also provides an ultra-thin aluminum alloy sheet coil prepared by the preparation method as described above.

[0034] The continuously extruded and rolled aluminum alloy ultra-thin sheet coil and the preparation method thereof of the present invention have the following beneficial effects compared with the prior art:

[0035] (1) By using aluminum alloy waste as the main raw material and optimizing the pretreatment, smelting, refining, casting, extrusion and rolling processes based on the technical problems existing in the recycling and reuse of aluminum alloy waste, the efficient reuse of aluminum alloy waste and the preparation of high-quality ultra-thin plates are achieved, which can effectively improve the purity and uniformity of aluminum alloy waste and significantly improve the mechanical properties of aluminum alloy plates. At the same time, it reduces energy consumption and pollution emissions in the production process, and has high industrial application value and environmental protection significance;

[0036] (2) Through the method of crushing treatment and cleaning agent combined with ultrasonic cleaning, the oil, oxide film and other impurities on the surface of the recycled aluminum waste are effectively removed, ensuring the high purity of the waste. The crushing treatment increases the specific surface area of ​​the material and improves the cleaning efficiency. The components such as sodium metasilicate pentahydrate in the cleaning agent decompose oil and oxides, trisodium citrate and alcohol ether phosphate deeply remove stubborn attached impurities, and triethanolamine oleate and isopropyl alcohol improve wettability and dispersibility, thereby preventing the waste substrate from being corroded or oxidized.

[0037] (3) The composite refining agent achieves deep purification of the aluminum alloy melt through the synergistic effect of multiple components. NaCl and Na3AlF6 as basic molten salts provide excellent coverage and fluidity, helping inclusions to float out; Al-10Nb and ScF3 promote grain refinement and uniform distribution of iron-rich phases during the static process, enhancing the alloy structure and properties; CeO2 and MnCl2 effectively remove stubborn impurities such as carbides and small oxide particles, and at the same time, cooperate with Al2Cu to enhance the dispersion and capture efficiency of inclusions. The entire refining process improves the purity and uniformity of the melt;

[0038] (4) During the extrusion stage, the heating rate and holding time of the short bar are precisely controlled to effectively eliminate the thermal stress during the heating process and ensure the dissolution and uniform distribution of the precipitated phase. During the rolling stage, the thickness of the prepared ultra-thin sheet coil is ensured to be less than 0.5 mm by precisely controlling the number of passes and temperature, while maintaining excellent mechanical properties and surface finish. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 The present invention is a flow chart of the method for preparing the aluminum alloy ultra-thin sheet coil;

[0041] Figure 2 This is a SEM image of the aluminum alloy ultra-thin sheet coil prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that the purity of the aluminum ingot used in this embodiment is ≥99.50%, and the aluminum alloy waste is the head and tail waste or edge waste cut off during the production and processing of 6063 aluminum alloy plates, including aluminum chips and aluminum blocks, with an aluminum content of >90%; Al-10Nb alloy was purchased from Suzhou Rongqian Rare Metal Products Co., Ltd.

[0044] Example 1

[0045] This embodiment provides a continuously extruded and rolled aluminum alloy ultra-thin sheet coil and a preparation method thereof, comprising the following steps:

[0046] S1. The recycled aluminum alloy waste is crushed to obtain fragments; the fragments are placed in a cleaning agent, and ultrasonic cleaning is performed at a temperature of 50° C. The ultrasonic power is 1000 W, and the cleaning time is 18 min. After the cleaning is completed, the pretreated aluminum alloy waste is obtained by washing with water and drying; wherein the cleaning agent comprises 125 g of sodium metasilicate pentahydrate, 40 g of trisodium citrate, 40 g of triethanolamine oleate, 65 g of fatty alcohol ether phosphate MOA-3P, 100 g of isopropyl alcohol, and 630 g of water;

[0047] S2, take 65kg of pre-treated aluminum alloy waste and 35kg of raw pure aluminum ingots for heating and melting, the melting temperature in the furnace is 740°C, after the raw materials in the furnace are melted, remove the scum, and obtain the initial alloy liquid;

[0048] S3, adding 0.13kg of composite refining agent to the initial alloy liquid, refining, refining temperature is 730℃, refining time is 50min, after refining, slag removal and furnace conduction are performed, and the alloy liquid is allowed to stand in the standing furnace for 25min, and then filtered and degassed to obtain the refined alloy liquid;

[0049] S4, casting the refined alloy liquid into aluminum alloy casting rods at a casting temperature of 700° C., with the diameter of the casting rods matching that of the extruder, and cutting the casting rods into short rods for extrusion;

[0050] S5. The short bar material is heated from room temperature to 390°C at a rate of 25°C / h, and kept warm for 3.5 hours; then the temperature is further heated to 425°C at a rate of 20°C / h, and kept warm for 4.5 hours; finally, the temperature is heated to 490°C at a rate of 15°C / h, and kept warm for 5.5 hours; after preheating, it is extruded at an extrusion temperature of 475°C, an extrusion speed of 3mm / s, and a discharge temperature of 450°C to produce an aluminum alloy plate;

[0051] S6. The aluminum alloy sheet is subjected to 26 initial rolling passes to be rolled into an intermediate plate with a thickness of 1.5-2.0 mm, and the initial rolling temperature is 485°C; after the initial rolling, intermediate annealing is performed, the annealing temperature is controlled at 380°C, and the insulation time is 1.5h; after the intermediate annealing, 7 finish rolling passes are performed to be rolled into an intermediate plate with a thickness of 0.2-0.5 mm, and the finish rolling temperature is 340°C; after the finish rolling, the sheet is coiled to obtain an aluminum alloy ultra-thin sheet coil.

[0052] The preparation method of the composite refining agent includes: weighing 26g NaCl, 20g Na3AlF6, 11g Al-10Nb, and 9g Al2Cu, mixing them, stirring them evenly, heating them to melt, and then cooling and crushing the mixture into particles to obtain a premix; mixing the premix with 7g MnCl2, 6g ScF3, 9g CeO2 and 2.5g polyethylene glycol evenly, pressing them into blocks, and obtaining a refining agent.

[0053] Example 2

[0054] This embodiment provides a continuously extruded and rolled aluminum alloy ultra-thin sheet coil and a preparation method thereof, comprising the following steps:

[0055] S1. The recycled aluminum alloy waste is crushed to obtain fragments; the fragments are placed in a cleaning agent, and ultrasonic cleaning is performed at a temperature of 45° C. The ultrasonic power is 1000 W, and the cleaning time is 20 min. After the cleaning is completed, the pretreated aluminum alloy waste is obtained by washing with water and drying; wherein the cleaning agent comprises 100 g of sodium metasilicate pentahydrate, 30 g of trisodium citrate, 30 g of triethanolamine oleate, 50 g of fatty alcohol ether phosphate MOA-3P, 80 g of isopropyl alcohol, and 710 g of water;

[0056] S2, take 60kg of pre-treated aluminum alloy waste and 30kg of raw pure aluminum ingots for heating and melting, the melting temperature in the furnace is 730°C, after the raw materials in the furnace are melted, remove the slag to obtain the initial alloy liquid;

[0057] S3, adding 0.1kg of composite refining agent to the initial alloy liquid, refining, refining temperature is 720℃, refining time is 60min, after refining, slag removal and furnace conduction are performed, and the alloy liquid is allowed to stand in the standing furnace for 20min, and filtered and degassed after standing to obtain the refined alloy liquid;

[0058] S4, casting the refined alloy liquid into aluminum alloy casting rods at a casting temperature of 695° C., with the diameter of the casting rods matching that of the extruder, and cutting the casting rods into short rods for extrusion;

[0059] S5, heating the short bar from room temperature to 380°C at a rate of 10°C / h, and keeping it warm for 4h; then heating it to 400°C at a rate of 10°C / h, and keeping it warm for 5h; finally heating it to 480°C at a rate of 10°C / h, and keeping it warm for 6h; after preheating, extruding it, the extrusion temperature is 470°C, the extrusion speed is 2mm / s, and the discharge temperature is 440°C to make an aluminum alloy plate;

[0060] S6. The aluminum alloy sheet is subjected to 25 initial rolling passes to be rolled into an intermediate plate with a thickness of 1.5-2.0 mm, and the initial rolling temperature is 480°C; after the initial rolling, intermediate annealing is performed, the annealing temperature is controlled at 360°C, and the insulation time is 2h; after the intermediate annealing, 6 finishing rolling passes are performed to be rolled into an intermediate plate with a thickness of 0.2-0.5 mm, and the finishing rolling temperature is 330°C; after finishing rolling, coiling is performed to obtain an aluminum alloy ultra-thin sheet coil.

[0061] The preparation method of the composite refining agent includes: weighing 25g NaCl, 18g Na3AlF6, 10g Al-10Nb, and 8g Al2Cu, mixing them, stirring them evenly, heating them to melt, and then cooling and crushing the mixture into particles to obtain a premix; mixing the premix with 6g MnCl2, 5g ScF3, 8g CeO2 and 2g polyethylene glycol evenly, pressing them into blocks, and obtaining a refining agent.

[0062] Example 3

[0063] This embodiment provides a continuously extruded and rolled aluminum alloy ultra-thin sheet coil and a preparation method thereof, comprising the following steps:

[0064] S1. The recycled aluminum alloy waste is crushed to obtain fragments; the fragments are placed in a cleaning agent, and ultrasonic cleaning is performed at a temperature of 55° C. The ultrasonic power is 800 W, and the cleaning time is 15 min. After the cleaning is completed, the pretreated aluminum alloy waste is obtained by washing with water and drying; wherein the cleaning agent comprises 150 g of sodium metasilicate pentahydrate, 50 g of trisodium citrate, 50 g of triethanolamine oleate, 80 g of fatty alcohol ether phosphate MOA-3P, 120 g of isopropyl alcohol, and 550 g of water;

[0065] S2, take 70kg of pre-treated aluminum alloy waste and 30kg of raw pure aluminum ingots for heating and melting, the melting temperature in the furnace is 750°C, after the raw materials in the furnace are melted, remove the slag to obtain an initial alloy liquid;

[0066] S3, adding 0.15kg of composite refining agent to the initial alloy liquid, refining, refining temperature is 740℃, refining time is 40min, after refining, slag removal and furnace conduction are performed, and the alloy liquid is allowed to stand in the standing furnace for 30min, and after standing, filtered and degassed to obtain the refined alloy liquid;

[0067] S4, casting the refined alloy liquid into aluminum alloy casting rods at a casting temperature of 715° C., with the diameter of the casting rods matching that of the extruder, and cutting the casting rods into short rods for extrusion;

[0068] S5, heating the short bar from room temperature to 400°C at a rate of 50°C / h, and keeping it warm for 3h; then heating it to 450°C at a rate of 40°C / h, and keeping it warm for 4h; finally heating it to 500°C at a rate of 30°C / h, and keeping it warm for 5h; after preheating, extruding it, the extrusion temperature is 480°C, the extrusion speed is 4mm / s, and the discharge temperature is 460°C to make an aluminum alloy plate;

[0069] S6. The aluminum alloy sheet is subjected to 28 initial rolling passes to be rolled into an intermediate plate with a thickness of 1.5-2.0 mm, and the initial rolling temperature is 490°C; after the initial rolling, intermediate annealing is performed, the annealing temperature is controlled at 400°C, and the insulation time is 1h; after the intermediate annealing, 8 finishing rolling passes are performed to be rolled into an intermediate plate with a thickness of 0.2-0.5 mm, and the finishing rolling temperature is 350°C; after finishing rolling, coiling is performed to obtain an aluminum alloy ultra-thin sheet coil.

[0070] The preparation method of the composite refining agent includes: weighing 28g NaCl, 22g Na3AlF6, 12g Al-10Nb, and 10g Al2Cu, mixing them, stirring them evenly, heating them to melt, and then cooling and crushing the mixture into particles to obtain a premix; mixing the premix with 8g MnCl2, 7g ScF3, 10g CeO2 and 3g polyethylene glycol evenly, pressing them into blocks, and obtaining a refining agent.

[0071] Comparative Example 1

[0072] This comparative example provides a continuously extruded and rolled aluminum alloy ultra-thin sheet coil and a preparation method thereof, comprising the following steps:

[0073] S1. The recycled aluminum alloy waste is crushed to obtain fragments; the fragments are ultrasonically cleaned at a temperature of 50° C., the ultrasonic power is 800-1000W, and the cleaning time is 18 minutes. After the cleaning is completed, the fragments are washed with water and dried to obtain pretreated aluminum alloy waste, wherein the ultrasonic cleaning includes sodium hydroxide cleaning, water cleaning, phosphoric acid cleaning and water cleaning;

[0074] S2-S6 are the same as in Example 1.

[0075] Comparative Example 2

[0076] This comparative example provides a continuously extruded and continuously rolled aluminum alloy ultra-thin sheet coil and a preparation method thereof, comprising the following steps: Steps S1-S6 are the same as those in Example 1, except that:

[0077] The preparation method of the composite refining agent includes: weighing 26g NaCl, 20g Na3AlF6, 11g Al-10Nb, and 9g Al2Cu, mixing them, stirring them evenly, heating them to melt, and then cooling and crushing the mixture into particles to obtain a premix; mixing the premix with 7g MnCl2 and 2.5g polyethylene glycol evenly, pressing them into blocks, and obtaining a refining agent.

[0078] Comparative Example 3

[0079] This comparative example provides a continuously extruded and continuously rolled aluminum alloy ultra-thin sheet coil and a preparation method thereof, comprising the following steps: Steps S1-S6 are the same as those in Example 1, except that:

[0080] The preparation method of the composite refining agent includes: weighing 26g NaCl, 20g Na3AlF6, 11g Al-10Nb, and 9g Al2Cu, mixing them, stirring them evenly, heating them to melt, and then cooling and crushing the mixture into particles to obtain a premix; mixing the premix with 7g MnCl2, 6g La, 9g Ce and 2.5g polyethylene glycol evenly, pressing them into blocks to obtain a refining agent.

[0081] Comparative Example 4

[0082] This comparative example provides a continuously extruded and rolled aluminum alloy ultra-thin sheet coil and a preparation method thereof, comprising the following steps:

[0083] S1-S4 are the same as in Example 1;

[0084] S5, heating the short bar from room temperature to 490°C at a rate of 25°C / h, and keeping the temperature for 13.5h; after preheating, extruding at a temperature of 475°C, an extrusion speed of 3mm / s, and a discharge temperature of 450°C to produce an aluminum alloy plate;

[0085] S6. The aluminum alloy sheet is subjected to 26 initial rolling passes to be rolled into an intermediate plate with a thickness of 1.5-2.0 mm, and the initial rolling temperature is 485°C; after the initial rolling, intermediate annealing is performed, the annealing temperature is controlled at 380°C, and the insulation time is 1.5h; after the intermediate annealing, 7 finish rolling passes are performed to be rolled into an intermediate plate with a thickness of 0.2-0.5 mm, and the finish rolling temperature is 340°C; after the finish rolling, the sheet is coiled to obtain an aluminum alloy ultra-thin sheet coil.

[0086] Performance Testing

[0087] The aluminum alloy ultra-thin sheet coils prepared in Examples 1-3 and Comparative Examples 1-4 were taken and their elongation, yield strength and tensile strength were measured using a universal tensile testing machine in accordance with GB / T228.1-2010. The test results are shown in Table 1.

[0088] Table 1 Performance test results

[0089] Elongation(%) Yield strength (MPa) Tensile strength(MPa) Example 1 16.72 224 238 Example 2 15.84 215 221 Example 3 16.25 231 232 Comparative Example 1 15.37 209 211 Comparative Example 2 14.78 184 186 Comparative Example 3 14.19 195 197 Comparative Example 4 12.17 202 206

[0090] Figure 2 The SEM image of the aluminum alloy ultra-thin sheet coil prepared in Example 1 of the present invention is shown. From the image, it can be seen that the alloy phase is evenly distributed in the present invention, and the needle-shaped iron-rich phase is obviously refined. As shown in Table 1, the aluminum alloy ultra-thin sheet coil prepared by the technical solution of the present invention has good elongation, yield strength and tensile strength.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an ultra-thin aluminum alloy sheet coil by continuous extrusion and rolling, characterized in that: The following steps are involved: S1. Pre-treating the recycled aluminum alloy waste to obtain pre-treated aluminum alloy waste, wherein the recycled aluminum alloy waste is cutting aluminum waste collected from a factory workshop; S2, heating and melting the pretreated aluminum alloy waste and the raw material pure aluminum ingot in a mass ratio of 60-70:30-40, the melting temperature in the furnace is 730-750° C., and after the raw materials in the furnace are melted, the slag is removed to obtain an initial alloy liquid; S3, adding a composite refining agent to the initial alloy liquid for refining, the refining temperature is 720-740°C, the refining time is 40-60min, slag removal and furnace conduction are performed after refining, and the alloy liquid is allowed to stand in a standing furnace for 20-30min, filtered and degassed after standing to obtain a refined alloy liquid; the composite refining agent comprises the following chemical composition, by mass, NaCl: 25-28 parts, Na3AlF6: 18-22 parts, Al-10Nb: 10-12 parts, ScF3: 5-7 parts, CeO2: 8-10 parts, Al2Cu: 8-10 parts, MnCl2: 6-8 parts; S4, casting the refined alloy liquid into aluminum alloy casting rods at a casting temperature of 695-715° C., with the diameter of the casting rods matching that of the extruder, and cutting the casting rods into short rods for extrusion; S5, preheating the short bar to 480-500°C for extrusion to form an aluminum alloy plate; S6. Rolling and coiling the aluminum alloy sheet to obtain an aluminum alloy ultra-thin sheet coil.

2. The method for preparing an ultra-thin aluminum alloy sheet coil by continuous extrusion and rolling as claimed in claim 1, characterized in that: Step S1 specifically includes: S11, crushing the recycled aluminum alloy waste to obtain fragments; S12. Place the scraps in a cleaning agent and perform ultrasonic cleaning at a temperature of 45-55°C, an ultrasonic power of 800-1000W, and a cleaning time of 15-20min. After the cleaning is completed, wash with water and dry to obtain pretreated aluminum alloy scrap.

3. The method for preparing an ultra-thin aluminum alloy sheet coil by continuous extrusion and rolling as claimed in claim 2, characterized in that: The cleaning agent comprises 10-15wt% of sodium metasilicate pentahydrate, 3-5wt% of trisodium citrate, 3-5wt% of triethanolamine oleate, 5-8wt% of alcohol ether phosphate and 8-12wt% of isopropyl alcohol, and the balance is water.

4. The method for preparing an ultra-thin aluminum alloy sheet coil by continuous extrusion and rolling as claimed in claim 1, characterized in that: The added mass of the composite refining agent is 0.1-0.15wt% of the total mass of the aluminum alloy.

5. The method for preparing an ultra-thin aluminum alloy sheet coil by continuous extrusion and rolling as claimed in claim 1, characterized in that: The preparation method of the composite refining agent comprises: weighing NaCl, Na3AlF6, Al-10Nb and Al2Cu in proportion, mixing them, stirring them evenly, heating and melting them, and then cooling and crushing the mixture into particles to obtain a premix; mixing the premix with MnCl2, ScF3, CeO2 and polyethylene glycol evenly, pressing them into blocks to obtain a refining agent.

6. The method for preparing an ultra-thin aluminum alloy sheet coil by continuous extrusion and rolling as claimed in claim 1, characterized in that: Step S5 specifically includes: preheating the short bar material to 480-500°C in sections, extruding, the extrusion temperature is 470-480°C, the extrusion ratio is 25-35:1, the extrusion speed is 2-4mm / s, the discharge temperature is 440-460°C, and the aluminum alloy plate is made.

7. The method for preparing an ultra-thin aluminum alloy sheet coil by continuous extrusion and rolling as claimed in claim 6, characterized in that: In step S5, the segmented preheating specifically includes: heating the short bar from room temperature to 380-400°C at a rate of ≤50°C / h, and keeping it warm for 3-4h; then continuing to heat it to 400-450°C at a rate of ≤40°C / h, and keeping it warm for 4-5h; finally heating it to 480-500°C at a rate of ≤30°C / h, and keeping it warm for 5-6h.

8. The method for preparing an ultra-thin aluminum alloy sheet coil by continuous extrusion and rolling as claimed in claim 1, characterized in that: Step S6 specifically includes: S61, performing 25-28 initial rolling of the aluminum alloy plate to form an intermediate plate with a thickness of 1.5-2.0 mm, with the initial rolling temperature being 480-490° C.; S62, intermediate annealing is performed after initial rolling, the annealing temperature is controlled at 360-400°C, and the holding time is 1-2h; S63, after intermediate annealing, 6-8 passes of finishing rolling are performed to roll the intermediate plate with a thickness of 0.2-0.5 mm, and the finishing rolling temperature is 330-350°C; S64, after fine rolling, coiling is performed to obtain an aluminum alloy ultra-thin sheet coil.

9. An ultra-thin aluminum alloy sheet coil produced by the production method according to any one of claims 1 to 8.

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