High-strength and high-toughness aluminum alloy and preparation method thereof

Abstract

The invention provides a preparation method of a high-strength and high-toughness aluminum alloy, which comprises the following steps: S1) proportioning according to the components of the aluminum alloy, and smelting to obtain an initial melt; s2) carrying out melt purification on the initial melt; s3) carrying out on-line two-stage filtration on the melt obtained in the step S2), and then carrying out grain refinement; s4) casting the melt obtained in the step S3); s5) performing soaking treatment on the cast ingot obtained in the step S4); and (S6) the aluminum alloy obtained in the step (S4) is subjected to aftertreatment, and the high-strength and high-toughness aluminum alloy is obtained. In the process of preparing the high-strength and high-toughness aluminum alloy, through raw material control, melt purification, grain refinement, matching of a proper casting process and specific soaking treatment, a cast ingot with a high-purity melt, excellent casting performance and a uniform and fine structure is obtained; and therefore, the aluminum alloy material with high strength, high toughness, excellent corrosion resistance and low cost is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a high-strength and high-toughness aluminum alloy and a preparation method thereof. Background Art

[0002] With the development of the aviation industry, large-scale, stability and economy have become the most urgent needs for the development of aluminum alloys. In order to improve the strength and toughness of the product while ensuring that the corrosion resistance is not reduced, it is necessary to increase the content of strengthening phase elements in the alloy and match the appropriate proportion. However, as the degree of alloying increases, the difficulty of melting and casting increases sharply, and ultra-wide ingots are more difficult to engineer. In order to meet the comprehensive performance requirements of the plate, it is necessary to reasonably control the content and proportion of alloy elements; in order to ensure that the plate has good stability and long life, it is necessary to control the melt purity, ingot uniformity and density at an extremely high level. At the same time, as the composition range narrows and the requirements increase, the melt purification and casting process control window are difficult to explore and match, and the difficulty of ingot molding is also greatly increased. Therefore, in order to meet the comprehensive performance requirements of the product, it is necessary to develop and optimize the chemical composition, melt purification and casting process of the alloy.

[0003] Aluminum alloy sheets for aviation products are mainly used for frames, skins, wall panels, etc., of which rolled sheets account for about 60%. As aircraft develop towards high strength, light weight, reliability, and long life, while meeting the comprehensive performance of materials, low-cost engineering applications must be achieved. For aviation aircraft, the cost mainly includes the cost of raw materials, manufacturing costs, and use costs; the low density of aviation aluminum alloys limits the strength performance, and the development of products towards extreme sizes requires the ingot to be infinitely close to zero defects. Improving strength limits damage resistance, and high strength will also cause processing difficulties and yield rates. The main materials currently used in aviation are third-generation aluminum alloys represented by 2024 and 7050. The process technology of the materials has been very mature after decades of development, and it is difficult to reduce the cost of raw materials and manufacturing by optimizing processes and processes. In order to reduce the cost of engineering applications, the cost of melting and casting low-density alloys is extremely high.

[0004] In order to meet the requirements of high strength and high toughness of materials, it is necessary to optimize the alloy composition ratio. However, while the strength and toughness of the alloy increase, the purity is extremely difficult to control, the casting performance deteriorates, and the production efficiency is low.

[0005] Therefore, it is of great significance to provide a preparation method to obtain an aluminum alloy with high purity melt, excellent comprehensive properties and low cost. Summary of the invention

[0006] The technical problem solved by the present invention is to provide a method for preparing a high-strength and high-toughness aluminum alloy, which can obtain a high-purity melt, excellent casting performance and a uniform and fine ingot structure, which is conducive to obtaining an aluminum alloy material with high strength, high toughness and excellent corrosion resistance.

[0007] In view of this, the present application provides a method for preparing a high-strength and high-toughness aluminum alloy, comprising the following steps:

[0008] S1) mixing the aluminum alloy according to its composition and then smelting it to obtain an initial melt;

[0009] S2) refining the initial melt with a granular refining agent, refining with high-purity argon gas through the bottom air bricks, and then refining with high-purity argon chlorine gas through a rotary degassing device, to obtain a melt with a hydrogen content of <0.08ml / 100gAl;

[0010] S3) performing online double-stage filtration on the melt obtained in step S2) and then performing grain refinement;

[0011] S4) Casting the melt obtained in step S3) at a casting speed of 40-55 mm / min and a water flow rate of 30-60 m / min. 3 / h / root, aluminum liquid temperature at the end of the flow plate is 695~715℃, water temperature is 20~28℃, and the wiper height is 200~500mm;

[0012] S5) performing a soaking treatment on the ingot obtained in step S4), wherein the first soaking treatment has a heating rate of 30-90°C / h, a heating temperature of 400-450°C, a holding temperature of 380-420°C, and a holding time of 5-12h, and the second soaking treatment has a heating rate of 5-20°C / h, a heating temperature of 470-480°C, a holding temperature of 465-475°C, and a holding time of 30-50h;

[0013] S6) deforming and heat treating the aluminum alloy obtained in step S4) to obtain a high-strength and high-toughness aluminum alloy;

[0014] The components of the high-strength and high-toughness aluminum alloy include: Si≤0.05%, Fe≤0.08%, Cu 2.0~2.4%, Mn≤0.02%, Mg 1.4~1.8%, Cr≤0.02%, Zn 7.8~8.6%, Ti≤0.05%, Zr 0.05~0.15%, Be≤0.005%, Na≤0.0003%, and the balance is Al.

[0015] Preferably, in step S1), the raw materials for the batching are specifically selected as: original aluminum ingots with a grade of Al99.95 or above, magnesium ingots with a grade of Mg99.9 or above, zinc ingots with a grade of Zn99.99 or above, high-purity AlSi master alloys, high-purity AlMn master alloys, high-purity AlZr master alloys, high-purity AlTi master alloys and primary waste.

[0016] Preferably, in step S2), the particle refining agent comprises: 50~58wt% KCl, 40~48wt% MgCl2, 0.1~1.0wt% NaCl, 0.1~1.0wt% H2O, 0.1~1.0wt% MgO, 0.1~1.0wt% CaCl2; the added amount of the particle refining agent is 0.8~1.5kg / t melt.

[0017] Preferably, in step S2), during the refining process using the granular refining agent, the refining time is 30-40 minutes, and the standing time is ≥45 minutes; during the refining process using the furnace bottom air brick, the temperature of the melt is 700-800°C, the time is 30-60 minutes, and the hydrogen content of the melt after refining is ≤0.20ml / 100gAl.

[0018] Preferably, in step S3), the filter plate of the online double-stage filtration is 30ppi+50ppi or 40ppi+60ppi.

[0019] Preferably, in step S3), the grain refining agent is Al-3Ti-0.15C, and the amount used is 2.0-4.0 kg / t melt.

[0020] Preferably, in step S5), the heating time of the first-stage heat treatment is 8 to 15 hours, and the heating time of the second-stage heat treatment is 5 to 20 hours.

[0021] Preferably, in step S4), the casting speed is 45-50 mm / min, and the water flow rate is 40-48 m / min. 3 / h / root, the aluminum liquid temperature at the end of the flow plate is 697~710℃, the water temperature is 24~26℃, and the wiper height is 300~450mm.

[0022] The present application also provides a high-strength and high-toughness aluminum alloy prepared by the preparation method, comprising: Si≤0.05wt%, Fe≤0.08wt%, Cu 2.0~2.4wt%, Mn≤0.02wt%, Mg 1.4~1.8wt%, Cr≤0.02wt%, Zn 7.8~8.6wt%, Ti≤0.05wt%, Zr 0.05~0.15wt%, Be 0.0005~0.005wt%, Na≤0.0003wt%, and the balance is Al.

[0023] Preferably, it includes: Si≤0.03wt%, Fe≤0.06wt%, Cu 2.2~2.3wt%, Mn≤0.01wt%, Mg 1.60~1.75wt%, Cr≤0.01wt%, Zn 7.85~8.15wt%, Ti≤0.02wt%, Zr 0.10~0.12wt%, and the balance is Al.

[0024] The present application provides a method for preparing a high-strength and high-toughness aluminum alloy, which firstly prepares materials according to an optimized composition of the aluminum alloy and then performs smelting to obtain an initial melt; then, a granular refining agent is used to refine the initial melt, and high-purity argon gas is used to refine it through the air-permeable bricks at the bottom of the furnace, and high-purity argon-chlorine gas is used to refine it through a rotating initial device to control the hydrogen content in the melt to be less than 0.08ml / 100gAl; then, the obtained melt is subjected to online double-stage filtration and grain refinement; the obtained melt is subsequently cast, and the parameters in the casting process are controlled, and finally, a heat treatment under specific conditions is performed; in the process of preparing the high-strength and high-toughness aluminum alloy, the present application obtains an ingot with a high-purity melt, excellent casting performance and uniform and fine structure by controlling the raw materials, the melt purification process, the grain refinement, matching the appropriate casting process and the specific heat treatment, that is, by regulating the chemical composition and preparation process of the aluminum alloy, an aluminum alloy material with high strength, high toughness and excellent corrosion resistance is obtained. DETAILED DESCRIPTION

[0025] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0026] In view of the requirements of aviation aluminum alloy materials for composition, the present application provides a method for preparing a high-strength and high-toughness aluminum alloy, which improves the strength of the material while maintaining the fracture toughness. When using the same thickness of the plate, the strength of the aluminum alloy material prepared by the present application is increased by more than 8% on the basis of the 7050 alloy, and the weight can be reduced by 5~10%, thereby reducing the use cost of the aircraft by reducing weight; compared with existing aerospace materials, it has higher strength, better damage resistance, better comprehensive performance, and the new material has a significant weight reduction effect of up to 5-10%; however, compared with the third-generation 7 series aluminum alloy, the casting molding, ingot internal structure and product performance stability control of the aluminum alloy of the present invention are more difficult, and the present application significantly improves the casting performance and production efficiency of the aluminum alloy material by controlling the chemical composition, melt quality and preparation process. Specifically, the embodiment of the present invention discloses a method for preparing a high-strength and high-toughness aluminum alloy, comprising the following steps:

[0027] S1) mixing the aluminum alloy according to its composition and then smelting it to obtain an initial melt;

[0028] S2) refining the initial melt with a granular refining agent, refining with high-purity argon gas through the bottom air bricks, and then refining with high-purity argon chlorine gas through a rotary degassing device, to obtain a melt with a hydrogen content of <0.08ml / 100gAl;

[0029] S3) performing online double-stage filtration on the melt obtained in step S2) and then performing grain refinement;

[0030] S4) Casting the melt obtained in step S3) at a casting speed of 40-55 mm / min and a water flow rate of 30-60 m / min. 3 / h / root, aluminum liquid temperature at the end of the flow plate is 695~715℃, water temperature is 20~28℃, and the wiper height is 200~500mm;

[0031] S5) performing a soaking treatment on the ingot obtained in step S4), wherein the first soaking treatment has a heating rate of 30-90°C / h, a heating temperature of 400-450°C, a holding temperature of 380-420°C, and a holding time of 5-12h, and the second soaking treatment has a heating rate of 5-20°C / h, a heating temperature of 470-480°C, a holding temperature of 465-475°C, and a holding time of 30-50h;

[0032] S6) deforming and heat treating the aluminum alloy obtained in step S4) to obtain a high-strength and high-toughness aluminum alloy;

[0033] The components of the high-strength and high-toughness aluminum alloy include: Si≤0.05%, Fe≤0.08%, Cu 2.0~2.4%, Mn≤0.02%, Mg 1.4~1.8%, Cr≤0.02%, Zn 7.8~8.6%, Ti≤0.05%, Zr 0.05~0.15%, Be≤0.005%, Na≤0.0003%, and the balance is Al.

[0034] In the preparation process of high-strength and high-toughness aluminum alloy, the present application firstly mixes the ingredients of the aluminum alloy and then smelts it to obtain an initial melt; in the process of mixing the ingredients, in order to meet the requirements of good casting performance and comprehensive performance of the alloy, the present application uses aluminum ingots with high purity and other raw materials with good uniformity, ensuring that impurities and trace elements such as Si, Fe, Mn, Cr, and Na are controlled at extremely low levels; for example, aluminum raw materials use aluminum ingots with a grade of Al99.95 or above, magnesium raw materials use magnesium ingots with a grade of Mg99.9 or above, zinc raw materials use zinc ingots with a grade of Zn99.99 or above, high-purity AlSi, AlMn, AlZr, AlTi intermediate alloys and high-purity primary waste, and the raw materials must be dry and pollution-free. After mixing the ingredients, the alloy raw materials are smelted to obtain an initial melt, and the melting temperature of the smelting is 700~800℃, and specifically, the melting temperature of the smelting is 740~760℃.

[0035] The present application further purifies the above-mentioned initial melt, firstly refines the initial melt with a particle refining agent, then refines it with high-purity argon gas through the air-permeable bricks at the bottom of the furnace, and then refines it with high-purity argon chlorine gas through a rotary degassing device; in the above process, the particle refining agent is blown into the melt for refining with high-purity argon gas, the purity of the high-purity argon gas is not less than 99.999%, the refining time is 30-40 minutes, and the melt is left to stand for not less than 45 minutes after refining, so that the slag after removal can fully float or precipitate, the particle refining agent includes: 50-58wt% KCl, 40-48wt% MgCl2, 0.1-1.0wt% NaCl, 0.1-1.0wt% H2O, 0.1-1.0wt% MgO, 0.1-1.0wt% CaCl2; the addition amount of the particle refining agent is 0.8-1.5 kg / t melt, the size of the particle refining agent is 2~3mm; specifically, the particle refining agent comprises: 52~56wt% KCl, 42~45wt% MgCl2, 0.2~0.8wt% NaCl, 0.15~0.75wt% H2O, 0.3~0.7wt% MgO, 0.12~0.60wt% CaCl2, more specifically, the particle refining agent comprises: 56wt% KCl, 42.5wt% MgCl2, 0.26wt% NaCl, 0.18wt% H2O, 0.3wt% MgO, 0.14wt% CaCl2; the addition amount of the particle refining agent is 1.0~1.2 kg / t melt.

[0036] In the process of refining with furnace bottom air-permeable bricks, the temperature of the melt is 700-800°C, the time is 30-60 minutes, and the hydrogen content of the melt after refining is ≤0.20ml / 100gAl. Specifically, the temperature of the melt is 740-760°C, the time is 40-50 minutes, and the hydrogen content of the melt after refining is ≤0.18ml / 100gAl. In the process of refining with high-purity argon-chlorine gas through a rotary degassing device, the purity of the high-purity argon-chlorine gas is not less than 99.999%. Preferably, argon gas can be used to protect the flow supply and degassing system. Finally, the hydrogen content of the melt is reduced to within 0.08ml / 100gAl. Further, the hydrogen content of the melt is reduced to 0.07ml / 100gAl.

[0037] According to the present invention, after the melt is purified and degassed online, it is filtered online; conventional melt filtration includes ceramic filter plates, deep beds and tubular filtration methods. With the improvement of the accuracy of the filter plates, the filtration gaps are smaller, more uniform, and more numerous, which is more conducive to the removal of fine inclusions in the melt. In order to ensure the uniformity and fine grain structure of aluminum alloy materials, it is necessary to intercept the slag and agglomerated refiners, while ensuring that the particles with its refinement effect pass through the filter device. According to the characteristics of the alloy and the requirements of production efficiency, the present invention proposes and applies double-stage filtration, specifically using 30ppi+50ppi or 40ppi+60ppi ceramic filter plates, selecting high-quality filter plates (few blind holes, good uniformity) as much as possible, and selecting large-sized or multiple filter plates to meet the requirements of throughput; preferably, the online filtration process equipment is also protected by argon.

[0038] The present application then performs grain refinement on the melt filtered online. Adding intermediate alloys containing Ti and B or Ti and C to the alloy can refine the cast grains, but too high an amount will form aggregated compounds. At the same time, due to the high degree of alloying and the greater difficulty in forming of the aluminum alloy of the present application, an extremely uniform and dense structure is required, and a rapid solidification method is also required, which will cause increased stress. Thus, the present invention preferably uses Al-3Ti-0.15C wire for grain refinement online, and the amount used is 2.0~4.0kg / t. Specifically, the amount of the Al-3Ti-0.15C wire is 2.5~3.5kg / t, and more specifically, the amount of the Al-3Ti-0.15C wire is 3.0kg / t.

[0039] According to the present invention, casting is performed after grain refinement; in order to obtain an ingot with better performance, a faster casting speed is generally used, which can make the ingot grains finer and the ingot density higher, but the alloying degree is higher, the melt fluidity is very poor, and the solidification process is prone to insufficient shrinkage. Too high a degree of shrinkage will increase the tendency to crack and cause insufficient melt flow; with the increase of cooling intensity, the size of the primary crystal compound can be refined and regional segregation can be reduced. Therefore, in order to obtain good ingot quality and comprehensive product performance, in the casting process of this application, the casting speed is 40~55mm / min, and the water flow rate is 30~60m 3 / h / root, the aluminum liquid temperature at the end of the flow plate is 695~715℃, the water temperature is 20~28℃, and the wiper height is 200~500mm; specifically, the casting speed is 45~50mm / min, the water flow rate is 40~48m 3 / h / root, the aluminum liquid temperature at the end of the flow plate is 697~710℃, the water temperature is 24~26℃, and the wiper height is 300~450mm.

[0040] After research, the applicant found that in order to eliminate the stress of the ingot, reduce the segregation of the ingot, and make the residual phase generated during the casting process fully dissolved into the matrix, it is necessary to perform multi-stage, homogenization annealing treatment on the ingot. This kind of heat treatment can fully dissolve the strengthening phase. The parking time before the heat treatment should not exceed 10h; specifically, the heating rate of the first stage of the heat treatment is 30~90℃ / h, the heating temperature is 400~450℃, the heating time is 8~15h, the insulation temperature is 380~420℃, the insulation time is 5~12h, the heating rate of the second stage of the heat treatment is 5~20℃ / h, the heating temperature is 470~480℃, the heating time is 5~20h, the insulation temperature is 465~475℃, and the insulation time is 30~50h; specifically, the heating rate of the first stage of the heat treatment is 40~70℃ / h, the heating temperature is 410~440℃, and the heating time is 5~20h. The heating time is 9~12h, the insulation temperature is 390~410℃, the insulation time is 6~10h, the heating rate of the second level heat treatment is 7~18℃ / h, the heating temperature is 470~480℃, the heating time is 6~10h, the insulation temperature is 468~470℃, and the insulation time is 36~42h; more specifically, the heating rate of the first level heat treatment is 40℃ / h, the heating temperature is 410℃, the heating time is 9~12h, the insulation temperature is 410℃, and the insulation time is 8h, the heating rate of the second level heat treatment is 7℃ / h, the heating temperature is 470℃, the heating time is 10h, the insulation temperature is 470℃, and the insulation time is 36h.

[0041] Finally, the ingot after the soaking treatment is heated, rolled, stretched, and solution-aged to obtain the T7451 aluminum alloy sheet.

[0042] The composition of the high-strength and high-toughness aluminum alloy of the present application includes: Si≤0.05wt%, Fe≤0.08wt%, Cu 2.0~2.4wt%, Mn≤0.02wt%, Mg 1.4~1.8wt%, Cr≤0.02wt%, Zn 7.8~8.6wt%, Ti≤0.05wt%, Zr 0.05~0.15wt%, Be 0.0005~0.005wt%, Na≤0.0003wt%, and the balance is Al; specifically, the composition of the high-strength and high-toughness aluminum alloy includes: Si≤0.03wt%, Fe≤0.06wt%, Cu 2.2~2.3wt%, Mn≤0.01wt%, Mg 1.60~1.75wt%, Cr≤0.01wt%, Zn 7.85~8.15wt%, Ti≤0.02wt%, Zr 0.10~0.12wt%, and the balance is Al; for example, the composition of the high-strength and high-toughness aluminum alloy includes: Si0.03wt%, Fe0.05wt%, Cu2.25wt%, Mn0.01wt%, Cr0.01wt%, Mg1.65wt%, Zn8.10wt%, Ti0.02wt%, Zr0.11wt%, and Al balance; or, Si0.03wt%, Fe0.06wt%, Cu2.23wt%, Mn0.01wt%, Cr0.01wt%, Mg1.68wt%, Zn7.96wt%, Ti0.02wt%, Zr0.11wt%, and Al balance; or, Si0.03wt%, Fe0.05wt%, Cu2.29wt%, Mn0.01wt%, Cr0.01wt%, Mg1.71wt%, Zn8.06wt%, Ti0.02wt%, Zr0.11wt%, and Al balance.

[0043] For the aluminum alloy provided in the present application, its main strengthening phases are MgZn2 (η) phase and Al2Mg3Zn3 (T) phase. The increase in alloy strength is mainly related to the Zn and Mg contents and the Zn / Mg ratio, and increases with the increase of Zn, Mg contents and the Zn / Mg ratio; when Cu is added under a certain content of Zn and Mg, the corrosion resistance and plasticity of the alloy can be improved with the increase of Cu content; the increase of Zn element can generate more MgZn2 (η) phase and Al2Mg3Zn3 (T) phase, but too high Zn will cause the casting performance of the alloy to deteriorate by 9%; within the alloy range containing 6-% Zn and a certain Mg content, the elongation increases with the Cu content increasing to 3%, and the addition of Cu can increase the concentration of the supersaturated solid solution, thereby increasing the plasticity. Since the solid solubility of Mg in aluminum decreases with the increase of Zn content, the maximum strength and the alloy strength move to the side with low Mg content. In order to improve the strength, toughness and corrosion resistance of the alloy and meet the requirements of product weight reduction, the Zn content in the aluminum alloy is greatly increased, the Cu content is appropriately increased, and the Mg content is reduced. The present invention controls Cu 2.0-2.4%, Mg 1.4-1.8%, and Zn 7.8-8.6%.

[0044] The present application provides a high-strength and high-toughness aluminum alloy and its preparation method, which obtains a high-purity melt, excellent casting performance and uniform and fine ingot structure through a series of steps including raw material selection, component matching, smelting, melt purification, melt filtration, grain refinement, casting, heat treatment, deformation and heat treatment, and finally obtains an aluminum alloy material with high strength, high toughness and excellent corrosion resistance, and reduces the cost. The tensile strength in three directions (L, LT, ST) is ≥500MPa, the yield strength in three directions (L, LT, ST) is ≥460MPa, the conductivity is ≥39.5%IACS, and the fracture toughness is: thickness ≤102mm, and the LT direction should be not less than 32MPa•m 1 / 2 ; Thickness>102 and ≤153mm, LT direction should be no less than 27MPa•m 1 / 2 .

[0045] In order to further understand the present invention, the high-strength and high-toughness aluminum alloy and the preparation method thereof provided by the present invention are described in detail below in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0046] Example 1

[0047] The aluminum alloy is prepared according to the following method: ingot selection, alloy element matching and control, raw material selection, smelting, furnace purification, online filtration, grain refinement, casting, soaking treatment, deformation and heat treatment in sequence;

[0048] Ingot selection: plate thickness 50 mm; ingot specification 520×1600 mm;

[0049] Raw material selection: Al99.95 grade original aluminum ingot, Cu99.95 grade copper plate, Mg99.9 grade magnesium ingot, Zn99.99 grade zinc ingot, AlCu, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots not lower than Al99.70 grade, and high-purity first-level waste materials;

[0050] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 746°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0051] Purification in the furnace: After the composition is adjusted, high-purity argon is used to blow granular refining agent into the melt in the furnace. The purity of argon should not be less than 99.999%. The size of the granular refining agent is 2.5mm. The granular refining agent includes 56% KCl, 42.5% MgCl2, 0.26% NaCl, 0.18% H2O, 0.30% MgO, and 0.14% CaCl2 by mass fraction. The amount of granular refining agent is 1.0kg / t melt. The time is 30 minutes, and the refining is allowed to stand for 50 minutes. After the powder spray refining in the furnace is qualified, it is transferred to the holding furnace. The melt is refined by high-purity argon gas through the air-permeable bricks at the bottom of the furnace. The melt temperature during refining is 742°C, the refining time is 50 minutes, and the hydrogen content of the melt after refining is 0.18mL / 100gAl; after the bottom of the furnace is refined by ventilation, it is refined by a high-purity argon-chlorine mixed gas through a rotary degassing device. After treatment, the hydrogen content of the melt is 0.07mL / 100gAl;

[0052] Online filtration: After online degassing, the melt is filtered using a 40+60ppi ceramic foam filter plate. The slag content after filtration is 0.008m 2 / kg;

[0053] Grain refinement: Al-3Ti-0.15C wire was used for grain refinement online, with a dosage of 3.0 kg / t;

[0054] Casting process: casting speed 50mm / min, water flow 40m 3 / h / root, aluminum liquid temperature of flow plate 695℃, water temperature 25℃, wiper height 450mm;

[0055] Heat treatment: The aluminum alloy ingots after casting are immediately subjected to heat treatment. The first-level homogenization annealing of the ingots has a heating rate of 30°C / h, a heating time of 12h, a holding temperature of 410°C, and a holding time of 8h. The second-level homogenization annealing of the ingots has a heating rate of 7°C / h, a heating time of 10h, a holding temperature of 470°C, and a holding time of 36h.

[0056] Deformation and heat treatment: After heating, rolling, stretching and solution aging, the ingot is converted into T7451 state 50mm thick plate.

[0057] After the above processes, the plates are sawn, flaw-detected and performance-tested before being packaged and delivered.

[0058] Quality Inspection:

[0059] (1) Macroscopic examination of ingot: grain size 2.5; the test method is GB / T3246.2 "Test Methods for Microstructure of Deformed Aluminum and Aluminum Alloy Products - Part 2 Macroscopic Examination Method";

[0060] (2) Chemical composition: Si0.03%, Fe0.05%, Cu2.25%, Mn0.01%, Cr0.01%, Mg1.65%, Zn8.10%, Ti0.02%, Zr0.11%, Al remainder; the detection method is GB / T 20975 "Analysis method of aluminum alloy" and GB / T 7999 "Photoelectric direct reading emission spectroscopy analysis method of aluminum and aluminum alloy";

[0061] (3) Hydrogen content: 0.07mL / 100g Al; the detection method is YS / T600 "Liquid Hydrogen Measurement Method for Aluminum and Aluminum Alloy Closed Circuit Method"; slag content: 0.008m 2 / kg, the detection method is YS / T1681 "Offline slag content detection method for deformed aluminum and aluminum alloy melts";

[0062] (4) Mechanical properties: tensile strength 557MPa, yield strength 513MPa, elongation 14%. The test method is GB / T16865 "Specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products";

[0063] (5) Fracture toughness: 43.89MPa•m 1 / 2 The test method is GB / T 4161 "Plane Strain Fracture Toughness K of Metallic Materials" IC Test Methods;

[0064] (6) Stress corrosion resistance: The sample did not crack after 20 days of testing. The testing method was HB / 5259 "Stress corrosion test method for aluminum alloy C ring sample";

[0065] (7) Exfoliation corrosion: EA level, the detection method is HB / 5455 "Test method for exfoliation corrosion of aluminum alloys".

[0066] Example 2

[0067] The aluminum alloy is prepared according to the following method: ingot selection, alloy element matching and control, raw material selection, smelting, furnace purification, online filtration, grain refinement, casting, soaking treatment, deformation and heat treatment in sequence;

[0068] Ingot selection: plate thickness 120mm; ingot specification 520×1600mm;

[0069] Raw material selection: Al99.95 grade original aluminum ingot, Cu99.95 grade copper plate, Mg99.9 grade magnesium ingot, Zn99.99 grade zinc ingot, AlCu, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots not lower than Al99.70 grade, and high-purity first-level waste materials;

[0070] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 745°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0071] Purification in the furnace: After the composition is adjusted, high-purity argon is used in the furnace to blow the granular refining agent into the melt. The purity of argon should be no less than 99.999%. The size of the granular refining agent is 2.5 mm. The granular refining agent includes 56% KCl, 42.5% MgCl2, 0.26% NaCl, 0.18% H2O, 0.30% MgO, and 0.14% CaCl2 by mass fraction. The amount of granular refining agent is 1.0 kg / t melt, the refining time is 30 min, and it is allowed to stand for 50 min after refining; after the powder spray refining in the furnace is qualified, it is transferred to the holding furnace. The melt is refined by high-purity argon through the air-permeable bricks at the bottom of the furnace. The melt temperature during refining is 744 ° C, the refining time is 50 min, and the hydrogen content of the melt after refining is 0.17 mL / 100 g Al; after being refined by ventilation at the bottom of the furnace, it is refined by a rotary degassing device using a high-purity argon-chlorine mixed gas. After treatment, the hydrogen content of the melt is 0.06mL / 100g Al;

[0072] Online filtration: After online degassing, the melt is filtered using a 40+60ppi ceramic foam filter plate. The slag content after filtration is 0.005m 2 / kg;

[0073] Grain refinement: Al-3Ti-0.15C wire was used for grain refinement online, with a dosage of 3.0 kg / t;

[0074] Casting process: casting speed 50mm / min, water flow 40m 3 / h / root, aluminum liquid temperature of flow plate 697℃, water temperature 24℃, wiper height 450mm;

[0075] Heat treatment: The aluminum alloy ingots after casting are immediately subjected to heat treatment. The first-level homogenization annealing of the ingots has a heating rate of 30°C / h, a heating time of 12h, a holding temperature of 410°C, and a holding time of 8h. The second-level homogenization annealing of the ingots has a heating rate of 7°C / h, a heating time of 10h, a holding temperature of 470°C, and a holding time of 36h.

[0076] Deformation and heat treatment: After heating, rolling, stretching and solution aging, the ingot is converted into T7451 state 120mm thick plate.

[0077] After the above processes, the plates are sawn, flaw-detected and performance-tested before being packaged and delivered.

[0078] Quality Inspection:

[0079] (1) Macroscopic examination of ingot: Grain size 2.0; the test method is GB / T3246.2 "Test Methods for Microstructure of Deformed Aluminum and Aluminum Alloy Products - Part 2 Macroscopic Examination Methods";

[0080] (2) Chemical composition: Si 0.03%, Fe 0.06%, Cu 2.23%, Mn 0.01%, Cr 0.01%, Mg 1.68%, Zn 7.96%, Ti 0.02%, Zr 0.11%, Al remainder; the detection method is GB / T 20975 "Analysis Method of Aluminum Alloy" and GB / T 7999 "Photoelectric Direct Reading Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloy";

[0081] (3) Hydrogen content: 0.06mL / 100g Al; the detection method is YS / T600 "Closed-circuit method for liquid hydrogen measurement of aluminum and aluminum alloys"; slag content: 0.005m 2 / kg, the detection method is YS / T1681 "Offline slag content detection method for deformed aluminum and aluminum alloy melts";

[0082] (4) Mechanical properties: tensile strength 547MPa, yield strength 511MPa, elongation 12%. The test method is GB / T16865 "Specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products".

[0083] (5) Fracture toughness: 29.50MPa•m 1 / 2 The test method is GB / T 4161 "Plane Strain Fracture Toughness K of Metallic Materials" IC Test Methods;

[0084] (6) Stress corrosion resistance: The sample did not crack after 20 days of testing. The testing method was HB / 5259 "Stress corrosion test method for aluminum alloy C ring sample";

[0085] (7) Exfoliation corrosion: EA level, the detection method is HB / 5455 "Test method for exfoliation corrosion of aluminum alloys".

[0086] Example 3

[0087] The aluminum alloy is prepared according to the following method: ingot selection, alloy element matching and control, raw material selection, smelting, furnace purification, online filtration, grain refinement, casting, soaking treatment, deformation and heat treatment in sequence;

[0088] Ingot selection: plate thickness 150mm; ingot specification 500×2000mm;

[0089] Raw material selection: Al99.95 grade original aluminum ingot, Cu99.95 grade copper plate, Mg99.9 grade magnesium ingot, Zn99.99 grade zinc ingot, AlCu, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots not lower than Al99.70 grade, and high-purity first-level waste materials;

[0090] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 745°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0091] Purification in the furnace: After the composition is adjusted, high-purity argon is used in the furnace to blow the granular refining agent into the melt. The purity of argon should be no less than 99.999%. The size of the granular refining agent is 2.5mm. The granular refining agent includes 56% KCl, 42.5% MgCl2, 0.26% NaCl, 0.18% H2O, 0.30% MgO, and 0.14% CaCl2 by mass fraction. The amount of granular refining agent is 1.0kg / t melt, the refining time is 30min, and it is allowed to stand for 50min after refining; after the powder spray refining in the furnace is qualified, it is transferred to the holding furnace, and the melt is refined by high-purity argon through the air-permeable bricks at the bottom of the furnace. The melt temperature during refining is 744℃, and the refining time is 50 min; the hydrogen content of the melt after refining is 0.18mL / 100g Al; after being refined by ventilation at the bottom of the furnace, it is refined by a rotary degassing device using a high-purity argon-chlorine mixed gas. After treatment, the hydrogen content of the melt is 0.06mL / 100g Al;

[0092] Online filtration: After online degassing, the melt is filtered using a 40+60ppi foam ceramic filter plate. The slag content after filtration is 0.004m 2 / kg;

[0093] Grain refinement: Al-3Ti-0.15C wire was used for grain refinement online, with a dosage of 3.0 kg / t;

[0094] Casting process: Casting speed 45mm / min, water flow 48m 3 / h / root, aluminum liquid temperature of flow plate 697℃, water temperature 24℃, wiper height 450mm;

[0095] Heat treatment: The aluminum alloy ingots after casting are immediately subjected to heat treatment. The first-level homogenization annealing of the ingots has a heating rate of 30°C / h, a heating time of 12h, a holding temperature of 410°C, and a holding time of 8h. The second-level homogenization annealing of the ingots has a heating rate of 7°C / h, a heating time of 10h, a holding temperature of 470°C, and a holding time of 36h.

[0096] Deformation and heat treatment: After heating, rolling, stretching and solution aging, the ingot is converted into T7451 state 150mm thick plate.

[0097] After the above processes, the plates are sawn, flaw-detected and performance-tested before being packaged and delivered.

[0098] Quality Inspection:

[0099] (1) Macroscopic examination of ingot: Grain size 2.0; the test method is GB / T3246.2 "Test Methods for Microstructure of Deformed Aluminum and Aluminum Alloy Products - Part 2 Macroscopic Examination Methods";

[0100] (2) Chemical composition: Si 0.03%, Fe 0.05%, Cu 2.29%, Mn 0.01%, Cr 0.01%, Mg 1.71%, Zn 8.06%, Ti 0.02%, Zr 0.11%, Al remainder; the detection method is GB / T 20975 "Analysis Method of Aluminum Alloy" and GB / T 7999 "Photoelectric Direct Reading Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloy";

[0101] (3) Hydrogen content: 0.06mL / 100g Al; the detection method is YS / T600 "Closed-circuit method for liquid hydrogen measurement of aluminum and aluminum alloys"; slag content: 0.004m 2 / kg, the detection method is YS / T1681 "Offline slag content detection method for deformed aluminum and aluminum alloy melts";

[0102] (4) Mechanical properties: tensile strength 532MPa, yield strength 494MPa, elongation 11%. The test method is GB / T16865 "Test specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products".

[0103] (5) Fracture toughness: 28.10MPa•m 1 / 2 The test method is GB / T 4161 "Plane Strain Fracture Toughness K of Metallic Materials" IC Test Methods;

[0104] (6) Stress corrosion resistance: The sample did not crack after 20 days of testing. The testing method was HB / 5259 "Stress corrosion test method for aluminum alloy C ring sample";

[0105] (7) Exfoliation corrosion: EA level, the detection method is HB / 5455 "Test method for exfoliation corrosion of aluminum alloys".

[0106] Comparative Example 1

[0107] The aluminum alloy is prepared according to the following method: ingot selection, alloy element matching and control, raw material selection, smelting, furnace purification, online filtration, grain refinement, casting, soaking treatment, deformation and heat treatment in sequence;

[0108] Ingot selection: plate thickness 150 mm; ingot specification 500×2000 mm;

[0109] Raw material selection: Al99.95 grade original aluminum ingot, Cu99.95 grade copper plate, Mg99.9 grade magnesium ingot, Zn99.99 grade zinc ingot, AlCu, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots not lower than Al99.70 grade, and high-purity first-level waste materials;

[0110] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 745°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0111] Purification in the furnace: After the composition is adjusted, high-purity argon is used in the furnace to blow the granular refining agent into the melt. The purity of argon should be no less than 99.999%. The size of the granular refining agent is 2.5 mm. The granular refining agent includes 56% KCl, 42.5% MgCl2, 0.26% NaCl, 0.18% H2O, 0.30% MgO, and 0.14% CaCl2 by mass fraction. The amount of granular refining agent is 1.0 kg / t melt, the refining time is 30 min, and it is allowed to stand for 50 min after refining; after the powder spray refining in the furnace is qualified, it is transferred to the holding furnace, and the melt is refined by high-purity argon through the air-permeable bricks at the bottom of the furnace. During the refining, the melt temperature is 744°C and the refining time is 50 min; the hydrogen content of the melt after refining is 0.18mL / 100g Al; after being refined by ventilation at the bottom of the furnace, it is refined by a rotary degassing device using a high-purity argon-chlorine mixed gas. After treatment, the hydrogen content of the melt is 0.06mL / 100g Al;

[0112] Online filtration: After online degassing, the melt is filtered using a 40+60ppi ceramic foam filter plate. The slag content after filtration is 0.007m 2 / kg;

[0113] Grain refinement: Al-3Ti-0.15C wire was used for grain refinement online, with a dosage of 3.0 kg / t;

[0114] Casting process: Casting speed 45mm / min, water flow 48m 3 / h / root, aluminum liquid temperature of flow plate 697℃, water temperature 24℃, wiper height 450mm;

[0115] Heat treatment: The cast aluminum alloy ingot is immediately subjected to heat treatment. The first-level homogenization annealing of the ingot has a heating rate of 30°C / h, a heating time of 12h, a holding temperature of 410°C, and a holding time of 8h. The second-level homogenization annealing of the ingot has a heating rate of 7°C / h, a heating time of 10h, a holding temperature of 470°C, and a holding time of 36h.

[0116] Deformation and heat treatment: After heating, rolling, stretching and solution aging, the ingot is converted into T7451 state 150mm thick plate.

[0117] After the above processes, the plates are sawn, flaw-detected and performance-tested before being packaged and delivered.

[0118] Quality Inspection:

[0119] (1) Macroscopic examination of ingot: Grain size 2.0; the test method is GB / T3246.2 "Test Methods for Microstructure of Deformed Aluminum and Aluminum Alloy Products - Part 2 Macroscopic Examination Methods";

[0120] (2) Chemical composition: Si 0.03%, Fe 0.05%, Cu 2.29%, Mn 0.01%, Cr 0.01%, Mg 1.71%, Zn 7.51%, Ti 0.02%, Zr 0.11%, Al remainder; the detection method is GB / T 20975 "Analysis Method of Aluminum Alloy" and GB / T 7999 "Photoelectric Direct Reading Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloy";

[0121] (3) Hydrogen content: 0.06mL / 100g Al; the detection method is YS / T600 "Closed-circuit method for liquid hydrogen measurement of aluminum and aluminum alloys"; slag content: 0.007m 2 / kg, the detection method is YS / T1681 "Offline slag content detection method for deformed aluminum and aluminum alloy melts";

[0122] (4) Mechanical properties: tensile strength 502MPa, yield strength 465MPa, elongation 13%. The test method is GB / T16865 "Specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products".

[0123] (5) Fracture toughness: 28.50MPa•m 1 / 2 The test method is GB / T 4161 "Plane Strain Fracture Toughness K of Metallic Materials" IC Test Methods;

[0124] (6) Stress corrosion resistance: The sample did not crack after 20 days of testing. The testing method was HB / 5259 "Stress corrosion test method for aluminum alloy C ring sample";

[0125] (7) Exfoliation corrosion: EA level, the detection method is HB / 5455 "Test method for exfoliation corrosion of aluminum alloys".

[0126] Since the Zn content of this comparative example is relatively low, the tensile strength and yield strength of the plate do not meet the product requirements and are scrapped.

[0127] Comparative Example 2

[0128] The aluminum alloy is prepared according to the following method: ingot selection, alloy element matching and control, raw material selection, smelting, furnace purification, online filtration, grain refinement, casting, soaking treatment, deformation and heat treatment in sequence;

[0129] Ingot selection: plate thickness 150mm; ingot specification 500×2000mm;

[0130] Raw material selection: Al99.95 grade original aluminum ingot, Cu99.95 grade copper plate, Mg99.9 grade magnesium ingot, Zn99.99 grade zinc ingot, AlCu, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots not lower than Al99.70 grade, and high-purity first-level waste materials;

[0131] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 745°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0132] Purification in the furnace: After the composition is adjusted, high-purity argon is used to blow granular refining agent into the melt in the furnace. The purity of argon should be no less than 99.999%. The size of the granular refining agent is 2.5 mm. The granular refining agent includes 56% KCl, 42.5% MgCl2, 0.26% NaCl, 0.18% H2O, 0.30% MgO, and 0.14% CaCl2 by mass fraction. The amount of granular refining agent is 1.0 kg / t melt, the refining time is 30 minutes, and it is allowed to stand for 50 minutes after refining; after the powder spray refining in the furnace is qualified, it is transferred to the insulation furnace, and the melt is refined by high-purity argon through the air bricks at the bottom of the furnace. During the refining, the melt temperature is 744°C and the refining time is 50 minutes; the hydrogen content of the melt after refining is 0.18 mL / 100 g Al; after refining through the bottom of the furnace, it is refined by a high-purity argon-chlorine mixed gas through a rotary degassing device. The hydrogen content of the melt after treatment is 0.07mL / 100g Al;

[0133] Online filtration: After online degassing, the melt is filtered using a 40+60 ppi ceramic foam filter plate. The slag content after filtration is 0.005m 2 / kg;

[0134] Grain refinement: Al-3Ti-0.15C wire is used for grain refinement online, with a dosage of 3.0kg / t

[0135] Casting process: casting speed 45 mm / min, water flow 48m 3 / h. root, flow plate aluminum liquid temperature 697℃, water temperature 24℃, wiper height 450mm;

[0136] Heat treatment: The aluminum alloy ingots after casting are immediately subjected to heat treatment. The first-level homogenization annealing of the ingots has a heating rate of 30°C / h, a heating time of 12h, a holding temperature of 410°C, and a holding time of 8h. The second-level homogenization annealing of the ingots has a heating rate of 7°C / h, a heating time of 10h, a holding temperature of 470°C, and a holding time of 36h.

[0137] Deformation and heat treatment: After heating, rolling, stretching and solution aging, the ingot is converted into T7451 state 150mm thick plate.

[0138] After the above processes, the plates are sawn, flaw-detected and performance-tested before being packaged and delivered.

[0139] Quality Inspection:

[0140] (1) Macroscopic examination of ingot: Grain size 2.0; the test method is GB / T3246.2 "Test Methods for Microstructure of Deformed Aluminum and Aluminum Alloy Products - Part 2 Macroscopic Examination Methods";

[0141] (2) Chemical composition: Si0.03%, Fe0.05%, Cu2.28%, Mn0.01%, Cr0.01%, Mg2.05%, Zn8.10%, Ti0.02%, Zr0.11%, Al remainder; the detection method is GB / T 20975 "Analysis method of aluminum alloy" and GB / T 7999 "Photoelectric direct reading emission spectroscopy analysis method of aluminum and aluminum alloy";

[0142] (3) Hydrogen content: 0.07mL / 100g Al; the detection method is YS / T600 "Closed-circuit method for liquid hydrogen measurement of aluminum and aluminum alloys"; slag content: 0.005m 2 / kg, the detection method is YS / T1681 "Offline slag content detection method for deformed aluminum and aluminum alloy melts";

[0143] (4) Mechanical properties: tensile strength 486MPa, yield strength 461MPa, elongation 13%, the test method is GB / T16865 "Specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products";

[0144] (5) Fracture toughness: 28.50MPa•m 1 / 2 The test method is GB / T 4161 "Plane Strain Fracture Toughness K of Metallic Materials" IC Test Methods;

[0145] (6) Stress corrosion resistance: The sample did not crack after 20 days of testing. The testing method was HB / 5259 "Stress corrosion test method for aluminum alloy C ring sample";

[0146] (7) Exfoliation corrosion: EA level, the detection method is HB / 5455 "Test method for exfoliation corrosion of aluminum alloys".

[0147] Since the Mg content of this comparative example is too high, the tensile strength and yield strength of the plate do not meet the product requirements and are scrapped.

[0148] Comparative Example 3

[0149] The aluminum alloy is prepared according to the following method: ingot selection, alloy element matching and control, raw material selection, smelting, melt purification, online filtration, grain refinement, and casting;

[0150] Ingot selection: plate thickness 150mm; ingot specification 500×2000mm;

[0151] Raw material selection: Al99.95 grade original aluminum ingot, Cu99.95 grade copper plate, Mg99.9 grade magnesium ingot, Zn99.99 grade zinc ingot, AlCu, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots not lower than Al99.70 grade, and high-purity first-level waste materials;

[0152] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 745°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0153] Purification in the furnace: After the composition is adjusted, high-purity argon is used in the furnace to blow the granular refining agent into the melt. The purity of argon should be no less than 99.999%. The size of the granular refining agent is 2.5mm. The granular refining agent includes 56% KCl, 42.5% MgCl2, 0.26% NaCl, 0.18% H2O, 0.30% MgO, and 0.14% CaCl2 by mass fraction. The amount of granular refining agent is 1.0kg / t melt, the refining time is 30min, and it is allowed to stand for 50min after refining; after the powder spray refining in the furnace is qualified, it is transferred to the insulation furnace, and the melt is refined by high-purity argon through the air bricks at the bottom of the furnace. During the refining, the melt temperature is 744℃ and the refining time is 50min; the hydrogen content of the melt after refining is 0.18mL / 100g Al; after refining through the bottom of the furnace, it is refined by a high-purity argon-chlorine mixed gas through a rotary degassing device. The hydrogen content of the melt after treatment is 0.06mL / 100g Al;

[0154] Online filtration: After online degassing, the melt is filtered using a 40+60ppi foam ceramic filter plate. The slag content after filtration is 0.004m 2 / kg;

[0155] Grain refinement: Al-5Ti-1B wire was used for grain refinement online, with a dosage of 1.5 kg / t;

[0156] Casting process: casting speed 45mm / min, water flow 48m 3 / h / root, aluminum liquid temperature of flow plate 697℃, water temperature 24℃, wiper height 450mm;

[0157] The comparative example uses Al-5Ti-1B for grain refinement, but the ingot is scrapped due to the presence of multiple cracks during the casting process.

[0158] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0159] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a high-strength and high-toughness aluminum alloy, comprising the following steps: S1) mixing the aluminum alloy according to its composition and then smelting it to obtain an initial melt; S2) refining the initial melt with a granular refining agent, refining with high-purity argon gas through the bottom air bricks, and then refining with high-purity argon chlorine gas through a rotary degassing device, to obtain a melt with a hydrogen content of <0.08ml / 100gAl; S3) performing online double-stage filtration on the melt obtained in step S2) and then performing grain refinement; S4) Casting the melt obtained in step S3) at a casting speed of 40-55 mm / min and a water flow rate of 30-60 m / min. 3 / h / root, aluminum liquid temperature at the end of the flow plate is 695~715℃, water temperature is 20~28℃, and the wiper height is 200~500mm; S5) performing a soaking treatment on the ingot obtained in step S4), wherein the first soaking treatment has a heating rate of 30-90°C / h, a heating temperature of 400-450°C, a holding temperature of 380-420°C, and a holding time of 5-12h, and the second soaking treatment has a heating rate of 5-20°C / h, a heating temperature of 470-480°C, a holding temperature of 465-475°C, and a holding time of 30-50h; S6) deforming and heat treating the aluminum alloy obtained in step S4) to obtain a high-strength and high-toughness aluminum alloy; The components of the high-strength and high-toughness aluminum alloy include: Si≤0.05%, Fe≤0.08%, Cu 2.0~2.4%, Mn≤0.02%, Mg1.4~1.8%, Cr≤0.02%, Zn 7.8~8.6%, Ti≤0.05%, Zr 0.05~0.15%, Be≤0.005%, Na≤0.0003%, and the balance is Al.

2. The preparation method according to claim 1, characterized in that: In step S1), the raw materials for the batching are specifically selected as: original aluminum ingots with a grade of Al99.95 or above, magnesium ingots with a grade of Mg99.9 or above, zinc ingots with a grade of Zn99.99 or above, high-purity AlSi master alloys, high-purity AlMn master alloys, high-purity AlZr master alloys, high-purity AlTi master alloys and primary scrap.

3. The preparation method according to claim 1, characterized in that: In step S2), the particle refining agent includes: 50-58wt% KCl, 40-48wt% MgCl2, 0.1-1.0wt% NaCl, 0.1-1.0wt% H2O, 0.1-1.0wt% MgO, and 0.1-1.0wt% CaCl2; the added amount of the particle refining agent is 0.8-1.5kg / t melt.

4. The preparation method according to claim 1, characterized in that: In step S2), during the refining process using the granular refining agent, the refining time is 30-40 minutes, and the standing time is ≥45 minutes; during the refining process using the furnace bottom air brick, the temperature of the melt is 700-800°C, the time is 30-60 minutes, and the hydrogen content of the melt after refining is ≤0.20ml / 100gAl.

5. The preparation method according to claim 1, characterized in that: In step S3), the filter plate of the online double-stage filtration is 30ppi+50ppi or 40ppi+60ppi.

6. The preparation method according to claim 1, characterized in that: In step S3), the grain refining agent is Al-3Ti-0.15C, and the amount used is 2.0-4.0 kg / t melt.

7. The preparation method according to claim 1, characterized in that: In step S5), the heating time of the first-stage heat treatment is 8 to 15 hours, and the heating time of the second-stage heat treatment is 5 to 20 hours.

8. The preparation method according to claim 1, characterized in that: In step S4), the casting speed is 45-50 mm / min, and the water flow rate is 40-48 m 3 / h / root, the aluminum liquid temperature at the end of the flow plate is 697~710℃, the water temperature is 24~26℃, and the wiper height is 300~450mm.

9. The high-strength and high-toughness aluminum alloy prepared by the preparation method according to any one of claims 1 to 8, comprising: Si≤0.05wt%, Fe≤0.08wt%, Cu 2.0~2.4wt%, Mn≤0.02wt%, Mg 1.4~1.8wt%, Cr≤0.02wt%, Zn 7.8~8.6wt%, Ti≤0.05wt%, Zr 0.05~0.15wt%, Be 0.0005~0.005wt%, Na≤0.0003wt%, and the balance is Al.

10. The aluminum alloy according to claim 9, characterized in that include: Si≤0.03wt%, Fe≤0.06wt%, Cu2.2~2.3wt%, Mn≤0.01wt%, Mg 1.60~1.75wt%, Cr≤0.01wt%, Zn 7.85~8.15wt%, Ti≤0.02wt%, Zr 0.10~0.12wt%, and the balance is Al.