Casting process of Al-Mg-Zn aluminum alloy and preparation method of Al-Mg-Zn aluminum alloy square cast ingot

Abstract

The invention provides a casting process of Al-Mg-Zn aluminum alloy, which comprises the following steps: casting an Al-Mg-Zn aluminum alloy melt after grain refinement, and in the casting process, not laying a bottom, not using a water wiper and using a cast iron base; and different casting water flows, speeds and crystallizer filling rates are adopted for different casting lengths. The invention further provides a preparation method of the Al-Mg-Zn aluminum alloy square cast ingot. According to the casting technology of the Al-Mg-Zn aluminum alloy, in the casting process, bottom laying is not needed, a water wiper is not used, a cast iron base is used, and casting technology parameters are optimized, so that the formability and structure uniformity and compactness of an aluminum alloy cast ingot are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, in particular to a casting process of an Al-Mg-Zn aluminum alloy and a preparation method of an Al-Mg-Zn aluminum alloy square ingot. Background Art

[0002] In order to improve the comprehensive protection capabilities of materials in high-end fields such as aerospace, lightweight materials or weight reduction are generally used while ensuring that the protective performance remains unchanged, which can greatly improve their ability to move and transfer.

[0003] Al-Mg-Zn aluminum alloys are a type of lightweight, high-strength material with Al as the matrix and Mg and Zn as the main alloying elements. They are widely used in aerospace, transportation, and industrial fields due to their excellent comprehensive performance. However, as the degree of alloying of Al-Mg-Zn aluminum alloys increases, their casting stress becomes larger. In order to prevent ingot cracking, technicians in this field generally use wipers during the casting process to reduce the casting stress and prevent cracking during the casting process. However, the use of wiper casting technology makes the production process complicated and costly, and also weakens secondary cooling, which is not conducive to microstructure refinement and worsens the shrinkage feeding performance, thereby affecting the microstructure uniformity of the ingot. Therefore, in order to achieve better ingot and product quality requirements, while achieving a short process and maximum economic benefits, it is necessary to develop a melting and casting process for Al-Mg-Zn aluminum alloys that eliminates the wiper. Summary of the Invention

[0004] The technical problem solved by the present invention is to provide a casting process for Al-Mg-Zn aluminum alloy. The casting process provided by the present application can reduce casting cracking, avoid cracking of aluminum alloy ingots, and has a dense, refined and uniform casting structure.

[0005] In view of this, the present application provides a casting process for an Al-Mg-Zn aluminum alloy, comprising:

[0006] Casting the grain-refined Al-Mg-Zn aluminum alloy melt, wherein no bottom is laid, no wiper is used, and a cast iron base is used during the casting process;

[0007] The water flow rate of the casting is specifically: when the casting length is 0mm, the water flow rate is 60-100m 3 / h, when the casting length is 100mm, the water flow rate is 50~90m 3 / h, when the casting length is 800mm, the water flow rate is 60~100m 3 / h until casting is completed;

[0008] The casting speed is specifically as follows: when the casting length is 0 mm, the casting speed is 42 to 55 mm / min; when the casting length is 50 mm, the casting speed is 40 to 53 mm / min; when the casting length is 200 mm, the casting speed is 42 to 55 mm / min;

[0009] The crystallizer filling rate of the casting is specifically: when the casting height is 0 mm, the crystallizer filling rate is 70-100 mm / min, when the casting height is 15 mm, the crystallizer filling rate is 60-90 mm / min, when the casting height is 30 mm, the crystallizer filling rate is 50-80 mm / min, and when the casting height is 60 mm, the crystallizer filling rate is 40-70 mm / min.

[0010] In some specific embodiments, the temperature of the aluminum liquid at the end of the casting flow plate is 690-715°C, and / or the temperature of the cooling water during the casting is 24-30°C.

[0011] In some specific embodiments, the composition of the Al-Mg-Zn aluminum alloy includes, by mass percentage, Cu 0.20-0.60%, Mn 0.30-0.70%, Mg 2.8-3.5%, Cr 0.10-0.20%, Zn 7.0-8.0%, Ti 0.03-0.10%, Zr 0.05-0.15%, Be 5-20ppm, Si≤0.12%, Fe≤0.15%, and the balance is Al.

[0012] The present application also provides a method for preparing an Al-Mg-Zn aluminum alloy square ingot, comprising the following steps:

[0013] According to the composition ratio of Al-Mg-Zn aluminum alloy square ingot, the raw materials after mixing are melted and the composition is adjusted;

[0014] The melt after composition adjustment is melt purified and then subjected to grain refinement;

[0015] Casting the melt after grain refinement to obtain an initial aluminum alloy square ingot, wherein the casting is the casting process described in the above scheme;

[0016] The initial aluminum alloy square ingot is subjected to a soaking treatment.

[0017] In some specific embodiments, the melting temperature is 720-770°C.

[0018] In some specific embodiments, the melt purification includes refining, online degassing and melt filtration performed in sequence, the refining temperature is 720-750°C, the time is 30-50 min, the refining atmosphere is high-purity argon, the online degassing atmosphere is high-purity argon, the hydrogen content of the melt after the online degassing is ≤0.15 ml / 100 g Al, and the melt filtration is performed using a ceramic filter plate with a ≥50 ppi.

[0019] In some specific embodiments, the grain refining agent is Al-5Ti-1B wire, and the amount of the Al-5Ti-1B wire used is 0.8-1.2 kg / t melt.

[0020] In some specific embodiments, the soaking treatment is performed at a heating rate of 40-60°C / h, a heating time of 8-12h, a temperature rise to 480-500°C, a holding temperature of 460-475°C, and a holding time of 30-40h.

[0021] In some specific embodiments, the thickness of the aluminum alloy square ingot is 400-450 mm.

[0022] In some specific embodiments, the aluminum alloy square ingot includes, by mass percentage, Cu 0.20-0.60%, Mn 0.30-0.70%, Mg 2.8-3.5%, Cr 0.10-0.20%, Zn 7.0-8.0%, Ti 0.03-0.10%, Zr 0.05-0.15%, Be 5-20ppm, Si≤0.12%, Fe≤0.15%, and the balance is Al.

[0023] The present application provides a casting process for Al-Mg-Zn aluminum alloy, which casts an Al-Mg-Zn aluminum alloy melt after grain refinement. During the casting process, no bottom is laid and no wiper is used, and a cast iron base is used. At the same time, different casting water flow rates, speeds and crystallizer filling rates are adopted according to different casting lengths during the casting process. In the casting process provided by the present application, not using a wiper is conducive to obtaining a denser and more refined and uniform casting structure. Using a cast iron base reduces the stress level in the starting casting stage, which facilitates warping and forming of the bottom of the ingot. At the same time, the casting parameters are optimized, the casting pressure at the beginning and during the casting process is reduced, and cracking of the ingot during the casting process is avoided.

[0024] The present application also provides a method for preparing an Al-Mg-Zn aluminum alloy square ingot, comprising the following steps: batching the ingredients according to the composition ratio of the Al-Mg-Zn aluminum alloy square ingot, melting the batched raw materials and then adjusting the composition; purifying the melt after the composition adjustment, and then refining the grains; casting the melt after grain refinement to obtain an initial aluminum alloy square ingot, wherein the casting is the casting process described in the above scheme; and subjecting the initial aluminum alloy square ingot to a uniform heat treatment. In the method for preparing the Al-Mg-Zn aluminum alloy square ingot, by introducing the above-mentioned specific casting process and coordinating it with other process steps, the quality of the ingot is guaranteed, the process requirements are shortened, and a high-strength and toughness aluminum alloy plate can be 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 problems in the prior art of Al-Mg-Zn aluminum alloy ingot molding and microstructure uniformity control, as well as the complex process flow, the present application provides a casting process for Al-Mg-Zn aluminum alloy. By not laying a bottom or using a wiper during the casting process, using a cast iron base, and optimizing the casting process parameters, the formability and microstructure uniformity and density of the aluminum alloy ingot are ensured. Specifically, the present application first provides a casting process for Al-Mg-Zn aluminum alloy, including:

[0027] Casting the grain-refined Al-Mg-Zn aluminum alloy melt, wherein no bottom is laid, no wiper is used, and a cast iron base is used during the casting process;

[0028] The water flow rate of the casting is specifically: when the casting length is 0mm, the water flow rate is 60-100m 3 / h, when the casting length is 100mm, the water flow rate is 50~90m 3 / h, when the casting length is 800mm, the water flow rate is 60~100m 3 / h until casting is completed;

[0029] The casting speed is specifically as follows: when the casting length is 0 mm, the casting speed is 42 to 55 mm / min; when the casting length is 50 mm, the casting speed is 40 to 53 mm / min; when the casting length is 200 mm, the casting speed is 42 to 55 mm / min;

[0030] The crystallizer filling of the casting is specifically as follows: when the casting height is 0 mm, the crystallizer filling rate is 70-100 mm / min, when the casting height is 15 mm, the crystallizer filling rate is 60-90 mm / min, when the casting height is 30 mm, the crystallizer filling rate is 50-80 mm / min, and when the casting height is 60 mm, the crystallizer filling rate is 40-70 mm / min.

[0031] In the Al-Mg-Zn aluminum alloy casting process provided in this application, a water wiper is not used, which ensures a dense and finely divided ingot structure, but increases the risk of cracking during casting. This application further optimizes the water flow rate, velocity, and mold filling rate during casting. The use of a cast iron base during the casting process reduces stress levels during the initial casting phase, facilitating warping and shaping of the ingot bottom.

[0032] During the casting process, the water flow rate of the casting is specifically: when the casting length is 0mm, the water flow rate is 60-100m 3 / h, when the casting length is 100mm, the water flow rate is 50~90m 3 / h, when the casting length is 800mm, the water flow rate is 60~100m 3 / h until the casting is completed; specifically, when the casting length is 0mm, the water flow rate is 80-95m 3 / h, when the casting length is 100mm, the water flow rate is 55~70m 3 / h, when the casting length is 800mm, the water flow rate is 80~95m 3 / h until the casting is completed; for the above water flow rate, the water flow rate for the casting length of 0mm is not just the water flow rate of 0mm, but the water flow rate for the casting length of 0mm to 100mm (not equal to 100mm) is 60~100m 3 / h. Similarly, when the casting length is from 100mm to 800mm (not equal to 800mm), the water flow rate is 50-90m 3 / h. Similarly, from the casting length of 800mm to the completion of casting, the water flow rate is 60-100m 3 / h.

[0033] The casting speed is specifically as follows: when the casting length is 0mm, the casting speed is 42-55mm / min, when the casting length is 50mm, the casting speed is 40-53mm / min, and when the casting length is 200mm, the casting speed is 42-55mm / min; for the above casting speeds, the casting speed of the casting length 0mm is not only the casting speed at the 0mm moment, but the casting speed is 42-55mm / min in the stage from 0mm to 50mm (not equal to 50mm) of the casting length. Similarly, the casting speed is 40-53mm / min in the stage from 50mm to 200mm (not equal to 200mm), and the casting speed is 42-55mm / min from the casting length of 200mm to the end of casting; specifically, when the casting length is 0mm, the casting speed is 47-54mm / min, when the casting length is 50mm, the casting speed is 41-46mm / min, and when the casting length is 200mm, the casting speed is 47-54mm / min.

[0034] The crystallizer filling rate of the casting is specifically: when the casting height is 0 mm, the crystallizer filling rate is 70-100 mm / min, when the casting height is 15 mm, the crystallizer filling rate is 60-90 mm / min, when the casting height is 30 mm, the crystallizer filling rate is 50-80 mm / min, and when the casting height is 60 mm, the crystallizer filling rate is 40-70 mm / min. As for the mold filling rate, the mold filling rate when the casting height is 0 mm is only the mold filling rate at the moment of 0 mm, but in the stage where the casting height is 0 to 15 mm (not equal to 15 mm), the mold filling rate is 70-100 mm / min. Similarly, in the stage where the casting height is 15 to 30 mm (not equal to 30 mm), the mold filling rate is 60-90 mm / min. Similarly, in the stage where the casting height is 30 to 60 mm (not equal to 60 mm), the mold filling rate is 50-80 mm / min. Similarly, from the casting height of 60 mm to the end of casting, the mold filling rate is 40-70 mm / min. Specifically, when the casting height is 0 mm, the mold filling rate is 85-95 mm / min, when the casting height is 15 mm, the mold filling rate is 64-84 mm / min, when the casting height is 30 mm, the mold filling rate is 56-83 mm / min, and when the casting height is 60 mm, the mold filling rate is 40-55 mm / min.

[0035] Furthermore, the temperature of the aluminum liquid at the end of the casting flow plate is 690-715°C, and the cooling water temperature is 24-30°C. Specifically, the temperature of the aluminum liquid at the end of the casting flow plate is 695-700°C, and the cooling water temperature is 26-28°C.

[0036] The composition of the Al-Mg-Zn aluminum alloy of the present application, in percentage by mass, includes: Cu 0.20-0.60%, Mn 0.30-0.70%, Mg 2.8-3.5%, Cr 0.10-0.20%, Zn 7.0-8.0%, Ti 0.03-0.10%, Zr 0.05-0.15%, Be 5-20ppm, Si≤0.12%, Fe≤0.15%, and the balance is Al.

[0037] In Al-Zn-Mg alloys, Zn and Mg are the main strengthening elements, and the main strengthening phases are MgZn2(η) phase and Al2Mg3Zn3(T) phase. The strength of the alloy increases with the increase of Zn and Mg content. Although increasing the Zn and Mg content can increase the strength, the toughness of the alloy deteriorates and the brittleness increases, which is not conducive to the comprehensive protective performance of the product. Therefore, the present invention controls the Mg content to 2.8-3.5% and the Zn content to 7.0-8.0%. Specifically, the Mg content is 2.95-3.40%, more specifically, the Mg content is 3.00-3.25%, more specifically, the Mg content is 3.10-3.20%. Specifically, the Zn content is 7.10-7.80%, more specifically, the Zn content is 7.20-7.65%, more specifically, the Zn content is 7.24-7.50%, more specifically, the Zn content is 7.30-7.40%.

[0038] Ti refines the ingot grain size and, like Zr, increases the recrystallization temperature and reduces the tendency to crack during casting and welding. However, Ti also introduces B. TiB2 particles are impurities, introduced as non-spontaneous nucleation particles, and are insoluble in the melt. Therefore, excessive Ti addition will not increase the grain size reduction capability and may even form coarse compounds, affecting the product's plasticity. Specifically, the Ti content is 0.05-0.07%.

[0039] Si and Fe are impurity elements that need to be controlled. Specifically, Si ≤ 0.05% and Fe ≤ 0.12%. Be is added during the preparation process to improve melt quality and prevent ingot cracking. Specifically, the Be content is 9ppm to 10ppm.

[0040] The simultaneous addition of Mn, Cr, and Zr to Al-Zn-Mg alloys is far more effective than adding just one or two of them. Through alloying, these elements form intermetallic compounds of varying dispersion, altering the distribution of dislocations within the grains and near grain boundaries. Cr can evenly distribute the decomposition products of the solid solution of Zn and Mg in aluminum within the grains. However, Mn, Cr, and Zr compounds are insoluble additives, and increasing their content increases the tendency to crack during welding and negatively impacts the strength of the weld. Adding a small amount of Zr to Al-Zn-Mg alloys containing Mn can also significantly reduce the tendency to stress corrosion. Adding trace amounts of Cu has little effect on general corrosion resistance, but can significantly improve the alloy's stress corrosion resistance. The present invention controls Cu 0.20-0.6%, Mn 0.30-0.7%, Cr 0.10-0.20%, and Zr 0.05-0.15%. Specifically, the Cu content is 0.28-0.50%, more specifically, the Cu content is 0.35-0.45%, and more specifically, the Cu content is 0.39-0.42%. Specifically, the Mn content is 0.38-0.62%, more specifically, the Mn content is 0.42-0.58%, and more specifically, the Mn content is 0.45-0.50%. Specifically, the Cr content is 0.12-0.18%, more specifically, the Cr content is 0.13-0.17wt%, and more specifically, the Cr content is 0.14-0.16%. Specifically, the Zr content is 0.07 to 0.12%, and more specifically, the Zr content is 0.09 to 0.11%.

[0041] The high-strength Al-Mg-Zn alloy and the medium-strength Al-Mg-Zn alloy used in the present invention have increased Cu, Mn, Mg, and Zn contents, with the Zn content significantly increased. This results in higher strength at the same mass, with a tensile strength of up to 600 MPa, and superior protective effects compared to existing alloys of equal weight. The aluminum alloy involved in the present invention is the primary load-bearing structure in the material, exhibiting excellent thermal deformation properties, ease of forming, and ease of processing. Under appropriate heat treatment conditions, it can achieve high strength, excellent weldability, and corrosion resistance. It is a high-strength, weldable aluminum alloy widely used in the vehicle and equipment fields.

[0042] The casting process of the aluminum alloy provided in this application preferably matches the composition of the above-mentioned aluminum alloy, and can further improve the comprehensive performance of the aluminum alloy on the basis of ensuring that there is no cracking during the casting process and the structure is uniform and dense.

[0043] Furthermore, the present application also provides a method for preparing an Al-Mg-Zn aluminum alloy square ingot, comprising the following steps:

[0044] According to the composition ratio of Al-Mg-Zn aluminum alloy square ingot, the raw materials after mixing are melted and the composition is adjusted;

[0045] The melt after composition adjustment is melt purified and then subjected to grain refinement;

[0046] Casting the melt after grain refinement to obtain an initial aluminum alloy square ingot, wherein the casting is the casting process described in the above scheme;

[0047] The initial aluminum alloy square ingot is subjected to a soaking treatment.

[0048] In the preparation method of Al-Mg-Zn aluminum alloy square ingots, the present application first prepares the ingredients according to the composition ratio of the Al-Mg-Zn aluminum alloy square ingots, wherein the raw materials are preferably selected from aluminum ingots with a grade of Al99.70 or above, scrap, master alloys, additives, and pure metals. Specifically, the alloy raw materials include: aluminum ingots with a grade of Al99.70, magnesium ingots with a grade of Al99.9, zinc ingots with a grade of Al99.99, master alloys of AlCu, AlMn, AlCr, AlBe, AlZr, and AlTi produced from aluminum ingots with a grade of not less than Al99.70, and first-grade scrap ingredients. The prepared raw materials are melted and the composition is adjusted. The melting temperature is 720-770°C, specifically 730-760°C, and more specifically 741-750°C.

[0049] According to the present invention, the melt after the composition adjustment is subjected to melt purification. In this application, the melt purification includes refining, online degassing and melt filtration performed in sequence. The refining temperature is 720-750°C, the time is 30-50min, the refining atmosphere is high-purity argon, the online degassing atmosphere is high-purity argon, the hydrogen content of the melt after the online degassing is ≤0.15ml / 100g Al, and the melt is filtered using a ceramic filter plate with a ≥50ppi; more specifically, the refining temperature is 730-746°C, the time is 30-40min; the hydrogen content of the melt after the online degassing is 0.10-0.12ml / 100g Al, and the melt is filtered using a 30+50ppi foam filter plate.

[0050] This application then performs grain refinement on the melt, and the refiner is selected from Al-5Ti-1B wire. The TiB2 particles formed by the refiner are easy to aggregate, thereby becoming a source of cracks in the ingot or causing uneven structure. While meeting the grain size requirements of the ingot, the addition amount needs to be limited. At the same time, Al-5Ti-1B wire with less slag content and refiner aggregation is selected to reduce the source of cracks in the casting process. The addition amount of Al-5Ti-1B wire in this application is 0.8~1.2kg / t. Specifically, the addition amount of the Al-5Ti-1B wire is 0.9~1.0kg / t.

[0051] According to the present invention, the grain-refined melt is then cast, which has been described in detail above and will not be described in detail here.

[0052] Finally, the present application performs a soaking treatment on the ingot after casting, and the soaking treatment is used to eliminate the stress of the ingot, reduce the segregation of the ingot and obtain a fine and dispersed compound, while making the strengthening phase dissolve evenly; the heating rate of the soaking treatment is 40-60°C / h, the heating time is 8-12h, the temperature is raised to 480-500°C, the holding temperature is 460-475°C, and the holding time is 30-40h. Specifically, the heating rate of the soaking treatment is 50-58°C / h, the heating time is 9-10h, the holding temperature is 465-470°C, and the time is 32-36h.

[0053] The thickness of the ingot prepared in this application is 400-450 mm, and the limitation of the ingot thickness is to further ensure the quality of the product.

[0054] In the preparation method of the Al-Mg-Zn aluminum alloy square ingot provided by the present invention, the main elements of the Al-Mg-Zn aluminum alloy square ingot are 8, which is the aluminum alloy with the most added elements currently; the total content of alloying elements is about 11.5%, which is 4% more than the conventional 7 series alloy, and the strength is increased by about 25%. Aluminum alloys need to maintain high strength and impact resistance, and also have good welding, corrosion resistance and processing properties. However, for Al-Mg-Zn series high-strength aluminum alloys, as the alloy composition becomes more complex and there are more refractory elements, the melt fluidity deteriorates, and the difficulty of ingot molding and microstructure control increases exponentially. The existing aluminum alloy casting technology has complex procedures and it is difficult to ensure the quality requirements of high-quality ingots. The present invention provides a preparation method of Al-Mg-Zn aluminum alloy square ingots. By adjusting the casting process and matching the ingot composition, specifications and other steps, the process flow is shortened, the metallurgical quality of the ingot can be improved, and the requirements of high-strength and tough plate products can be met.

[0055] In order to further understand the present invention, the casting process of the Al-Mg-Zn aluminum alloy and the preparation method of the Al-Mg-Zn aluminum alloy square ingot provided by the present invention are described in detail below in combination with the embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0056] Example 1

[0057] The Al-Mg-Zn aluminum alloy is prepared in the following steps: ingot specification selection, raw material selection, smelting process, melt purification, grain refinement, casting control, and soaking treatment. The specific process is as follows:

[0058] Ingot specification selection: Ingot specification 400×1620mm;

[0059] Raw material selection: select the following raw materials according to the composition ratio of the aluminum alloy and make batching to obtain alloy raw materials: Al99.70 grade original aluminum ingot, Al99.9 grade magnesium ingot, Al99.99 grade zinc ingot, AlCu, AlMn, AlCr, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots with a grade not lower than Al99.70, and first-level scrap batching;

[0060] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 751°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0061] Melt purification: After the composition is adjusted, the melt in the furnace is refined using high-purity argon at a temperature of 742°C for 30 minutes. The melt is then refined using high-purity argon in a rotary degassing device, achieving a hydrogen content of 0.12 mL / 100 g Al. After online degassing, the melt is filtered using a 30+50 ppi ceramic foam filter plate.

[0062] Grain refinement: AlTi5B1 wire was used for grain refinement online, with a dosage of 1.0 kg / t;

[0063] Casting control: Use cast iron base, no bottom laying and no wiper; Water flow: When the casting length is 0mm, the water flow is 80m 3 / h, when the casting length is 100mm, the water flow rate is 70m 3 / h, when the casting length is 800mm, the water flow rate is 80m 3 / h until casting is completed; Casting speed: When the casting length is 0mm, the casting speed is 47mm / min; when the casting length is 50mm, the casting speed is 45mm / min; when the casting length is 200mm, the casting speed is 51mm / min, until casting is completed; Crystallizer filling: When the casting height is 0mm, the crystallizer filling rate is 85mm / min; when the casting height is 15mm, the crystallizer filling rate is 75mm / min; when the casting height is 30mm, the crystallizer filling rate is 65mm / min; when the casting height is 60mm, the crystallizer filling rate is 55mm / min; Casting temperature: The aluminum liquid temperature at the end of the flow plate is 690-715℃; Cooling water temperature: 27℃;

[0064] Soaking treatment: The aluminum alloy ingot obtained by casting is immediately subjected to soaking treatment to obtain aluminum alloy square ingot, wherein the soaking treatment has a heating rate of 50°C / h, a heating time of 10h, a holding temperature of 465°C, and a holding time of 36h;

[0065] The ingot obtained by the soaking treatment is subjected to machining, milling, rolling, solution quenching, aging treatment, flaw detection and packaging to obtain qualified Al-Mg-Zn aluminum alloy plates.

[0066] The aluminum alloy square ingots and aluminum alloy plates obtained above were subjected to quality inspection:

[0067] (1) Macroscopic examination of ingot: Grain size is Grade 1; Oxide film meets Grade 1; The test method is GB / T3246.2 "Test Methods for Microstructure of Deformed Aluminum and Aluminum Alloy Products - Part 2 Macroscopic Examination Methods";

[0068] (2) Chemical composition: Si 0.05%, Fe 0.10%, Cu 0.35%, Mn 0.45%, Cr 0.16%, Mg 3.10%, Zn 7.30%, Ti 0.05%, Zr 0.11%, Be 9ppm; the detection method is GB / T 20975 "Analysis Method of Aluminum Alloys" and GB / T 7999 "Photoelectric Direct Reading Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloys";

[0069] (3) Hydrogen content: 0.12 mL / 100 g Al; the detection method is YS / T600 "Liquid Hydrogen Determination Method for Aluminum and Aluminum Alloys - Closed Circuit Method";

[0070] (4) Plate flaw detection: in compliance with Class A; the testing method is GB / T 6519 “Ultrasonic testing method for deformed aluminum and magnesium alloy products”;

[0071] (5) Mechanical properties: T6 state performance, tensile strength 621 MPa, yield strength 576 MPa, elongation 8%; the test method is GB / T 16865 "Test specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products".

[0072] Example 2

[0073] The Al-Mg-Zn aluminum alloy is prepared according to the following steps: ingot specification selection, raw material selection, smelting process, melt purification, grain refinement, casting control, and soaking treatment;

[0074] Ingot specification selection: Ingot specification 400×1620mm;

[0075] Raw material selection: select the following raw materials according to the composition ratio of the aluminum alloy and make batching to obtain alloy raw materials: Al99.70 grade original aluminum ingot, Al99.9 grade magnesium ingot, Al99.99 grade zinc ingot, AlCu, AlMn, AlCr, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots with a grade not lower than Al99.70, and first-level scrap batching;

[0076] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 748°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0077] Melt purification: After the composition is adjusted, the melt in the furnace is refined with high-purity argon at a temperature of 740°C for 40 minutes. The melt is then refined with high-purity argon in a rotary degassing device, achieving a hydrogen content of 0.10 mL / 100 g Al. After online degassing, the melt is filtered using a 30+50 ppi ceramic foam filter plate.

[0078] Grain refinement: AlTi5B1 wire was used for grain refinement online, with a dosage of 1.0 kg / t;

[0079] Casting control: Use cast iron base, no bottom laying and no wiper; Water flow: When the casting length is 0mm, the water flow is 80m 3 / h, when the casting length is 100mm, the water flow rate is 70m 3 / h, when the casting length is 800mm, the water flow rate is 80m 3 / h until casting is completed; Casting speed: When the casting length is 0mm, the casting speed is 47mm / min; when the casting length is 50mm, the casting speed is 45mm / min; when the casting length is 200mm, the casting speed is 51mm / min until casting is completed; Crystallizer filling: When the casting height is 0mm, the crystallizer filling rate is 85mm / min; when the casting height is 15mm, the crystallizer filling rate is 75mm / min; when the casting height is 30mm, the crystallizer filling rate is 65mm / min; when the casting height is 60mm, the crystallizer filling rate is 55mm / min; Casting temperature: The aluminum liquid temperature at the end of the flow plate is 690-715℃; Cooling water temperature: 28℃;

[0080] Heat treatment: The aluminum alloy ingot obtained by casting is immediately subjected to heat treatment to obtain an aluminum alloy square ingot; wherein, the heat treatment has a heating rate of 50°C / h, a heating time of 10h, a holding temperature of 465°C, and a holding time of 36h.

[0081] The ingots are subjected to machining, milling, rolling, solution quenching, aging treatment, flaw detection and packaging to obtain qualified Al-Mg-Zn aluminum alloy plates.

[0082] The aluminum alloy square ingots and aluminum alloy plates obtained above were subjected to quality inspection:

[0083] (1) Macroscopic examination of ingot: Grain size is Grade 1; Oxide film meets Grade 1; The test method is GB / T3246.2 "Test Methods for Microstructure of Deformed Aluminum and Aluminum Alloy Products - Part 2 Macroscopic Examination Methods";

[0084] (2) Chemical composition: Si 0.05%, Fe 0.12%, Cu 0.39%, Mn 0.42%, Cr 0.17%, Mg 3.20%, Zn 7.20%, Ti 0.05%, Zr 0.12%, Be 10 ppm; the detection method is GB / T 20975 "Analysis Method of Aluminum Alloys" and GB / T 7999 "Photoelectric Direct Reading Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloys";

[0085] (3) Hydrogen content: 0.10 mL / 100 g Al; the detection method is YS / T600 "Liquid Hydrogen Determination Method for Aluminum and Aluminum Alloys - Closed Circuit Method".

[0086] (4) Plate flaw detection: Meets Class A; the detection method is GB / T 6519 “Ultrasonic testing method for deformed aluminum and magnesium alloy products”.

[0087] (5) Mechanical properties: T6 state performance, tensile strength 630 MPa, yield strength 584 MPa, elongation 9%; the test method is GB / T 16865 "Test specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products".

[0088] Example 3

[0089] The Al-Mg-Zn aluminum alloy is prepared in the following steps: ingot specification selection, raw material selection, smelting process, melt purification, grain refinement, casting control, and soaking treatment. The specific process is as follows:

[0090] Ingot specification selection: Ingot specification 400×1620mm;

[0091] Raw material selection: select the following raw materials according to the composition ratio of the aluminum alloy and make batching to obtain alloy raw materials: Al99.70 grade original aluminum ingot, Al99.9 grade magnesium ingot, Al99.99 grade zinc ingot, AlCu, AlMn, AlCr, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots with a grade not lower than Al99.70, and first-level scrap batching;

[0092] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 753°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0093] Melt purification: After the composition is adjusted, the melt in the furnace is refined using high-purity argon at a temperature of 746°C for 40 minutes. The melt is then refined using high-purity argon in a rotary degassing device, achieving a hydrogen content of 0.11 mL / 100 g Al. After online degassing, the melt is filtered using a 30+50 ppi ceramic foam filter plate.

[0094] Grain refinement: AlTi5B1 wire was used for grain refinement online, with a dosage of 1.0 kg / t;

[0095] Casting control: Use cast iron base, no bottom laying and no wiper; Water flow: When the casting length is 0mm, the water flow is 80m 3 / h, when the casting length is 100mm, the water flow rate is 70m 3 / h, when the casting length is 800mm, the water flow rate is 80m 3 / h until casting is completed; Casting speed: When the casting length is 0mm, the casting speed is 47mm / min; when the casting length is 50mm, the casting speed is 45mm / min; when the casting length is 200mm, the casting speed is 51mm / min until casting is completed; Crystallizer filling: When the casting height is 0mm, the crystallizer filling rate is 85mm / min; when the casting height is 15mm, the crystallizer filling rate is 75mm / min; when the casting height is 30mm, the crystallizer filling rate is 65mm / min; when the casting height is 60mm, the crystallizer filling rate is 55mm / min; Casting temperature: The aluminum liquid temperature at the end of the flow plate is 690-715℃; Cooling water temperature: 26℃;

[0096] Heat treatment: The aluminum alloy ingot obtained by casting is immediately subjected to heat treatment to obtain an aluminum alloy square ingot, wherein the heat treatment has a heating rate of 50°C / h, a heating time of 10h, a holding temperature of 465°C, and a holding time of 36h.

[0097] The ingots are subjected to machining, milling, rolling, solution quenching, aging treatment, flaw detection and packaging to obtain qualified Al-Mg-Zn aluminum alloy plates.

[0098] The aluminum alloy square ingots and aluminum alloy plates obtained above were subjected to quality inspection:

[0099] (1) Macroscopic examination of ingot: Grain size is Grade 1; Oxide film meets Grade 1; 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 0.04%, Fe 0.08%, Cu 0.36%, Mn 0.45%, Cr 0.16%, Mg 3.25%, Zn 7.24%, Ti 0.05%, Zr 0.11%, Be 10 ppm; the detection method is GB / T 20975 "Analysis Method of Aluminum Alloys" and GB / T 7999 "Photoelectric Direct Reading Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloys";

[0101] (3) Hydrogen content: 0.11 mL / 100 g Al; the detection method is YS / T600 "Liquid Hydrogen Determination Method for Aluminum and Aluminum Alloys Closed Circuit Method";

[0102] (4) Plate flaw detection: in compliance with Class A; the testing method is GB / T 6519 “Ultrasonic testing method for deformed aluminum and magnesium alloy products”;

[0103] (5) Mechanical properties: T6 state performance, tensile strength 618 MPa, yield strength 584 MPa, elongation 9%; the test method is GB / T 16865 "Test specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products".

[0104] Comparative Example 1

[0105] The Al-Mg-Zn aluminum alloy is prepared in the following steps: ingot specification selection, raw material selection, smelting process, melt purification, grain refinement, casting control, and soaking treatment. The specific process is as follows:

[0106] Ingot specification selection: Ingot specification 400×1620mm;

[0107] Raw material selection: select the following raw materials according to the composition ratio of the aluminum alloy and make batching to obtain alloy raw materials: Al99.70 grade original aluminum ingot, Al99.9 grade magnesium ingot, Al99.99 grade zinc ingot, AlCu, AlMn, AlCr, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots with a grade not lower than Al99.70, and first-level scrap batching;

[0108] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 751°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0109] Melt purification: After the composition is adjusted, the melt in the furnace is refined with high-purity argon at a temperature of 740°C for 30 minutes. The melt is then refined with high-purity argon in a rotary degassing device, achieving a hydrogen content of 0.12 mL / 100 g Al. After online degassing, the melt is filtered using a 30+50 ppi ceramic foam filter plate.

[0110] Grain refinement: AlTi5B1 wire was used for grain refinement online, with a dosage of 1.0 kg / t;

[0111] Casting control: Aluminum base, no bottom and no wiper casting. Water flow: When the casting length is 0mm, the water flow is 80m 3 / h, when the casting length is 100mm, the water flow rate is 70m 3 / h, when the casting length is 800mm, the water flow rate is 80m 3 / h until casting is completed; Casting speed: When the casting length is 0mm, the casting speed is 47mm / min; when the casting length is 50mm, the casting speed is 45mm / min; when the casting length is 200mm, the casting speed is 51mm / min until casting is completed; Crystallizer filling: When the casting height is 0mm, the crystallizer filling rate is 85mm / min; when the casting height is 15mm, the crystallizer filling rate is 75mm / min; when the casting height is 30mm, the crystallizer filling rate is 65mm / min; when the casting height is 60mm, the crystallizer filling rate is 55mm / min; Casting temperature: The aluminum liquid temperature at the end of the flow plate is 690-715℃; Cooling water temperature: 27℃;

[0112] Soaking treatment: The cast aluminum alloy ingot is immediately subjected to soaking treatment to obtain aluminum alloy square ingots, wherein the soaking treatment has a heating rate of 50°C / h, a heating time of 10h, a holding temperature of 465°C, and a holding time of 36h;

[0113] After the casting was completed, the bottoms of three ingots were cracked and scrapped, and the bottom of another ingot was cracked 2000mm after machining, resulting in only one piece of rough material with a length of 2500mm being preserved.

[0114] Quality inspection:

[0115] (1) Macroscopic examination of ingot: grain size 1.5; oxide film meets the requirements of grade 1; the test method is GB / T3246.2 "Test methods for microstructure of wrought aluminum and aluminum alloy products - Part 2 Macroscopic examination method";

[0116] (2) Chemical composition: Si 0.05%, Fe 0.11%, Cu 0.36%, Mn 0.43%, Cr 0.16%, Mg 3.15%, Zn 7.28%, Ti 0.05%, Zr 0.11%, Be 9ppm; the detection method is GB / T 20975 "Analysis Method of Aluminum Alloys" and GB / T 7999 "Photoelectric Direct Reading Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloys";

[0117] (3) Hydrogen content: 0.12 mL / 100 g Al; the detection method is YS / T600 "Liquid Hydrogen Determination Method for Aluminum and Aluminum Alloys - Closed Circuit Method".

[0118] (4) Plate flaw detection: in compliance with Class A; the testing method is GB / T 6519 “Ultrasonic testing method for deformed aluminum and magnesium alloy products”;

[0119] (5) Mechanical properties: T6 state performance, tensile strength 628 MPa, yield strength 580 MPa, elongation 9%; the test method is GB / T 16865 "Test specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products".

[0120] Comparative Example 2

[0121] The Al-Mg-Zn aluminum alloy is prepared according to the following steps: ingot specification selection, raw material selection, smelting process, melt purification, grain refinement, casting control, and soaking treatment;

[0122] Ingot specification selection: Ingot specification 400×1620mm;

[0123] Raw material selection: select the following raw materials according to the composition ratio of the aluminum alloy and make batching to obtain alloy raw materials: Al99.70 grade original aluminum ingot, Al99.9 grade magnesium ingot, Al99.99 grade zinc ingot, AlCu, AlMn, AlCr, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots with a grade not lower than Al99.70, and first-level scrap batching;

[0124] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 748°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0125] Melt purification: After the composition is adjusted, the melt in the furnace is refined using high-purity argon at a temperature of 743°C for 40 minutes. The melt is then refined using high-purity argon in a rotary degassing device, achieving a hydrogen content of 0.11 mL / 100 g Al. After online degassing, the melt is filtered using a 30+50 ppi ceramic foam filter plate.

[0126] Grain refinement: AlTi5B1 wire was used for grain refinement online, with a dosage of 1.0 kg / t;

[0127] Casting control: Aluminum base, no bottom, and wiper casting; Water flow: When the casting length is 0mm, the water flow is 80m 3 / h, when the casting length is 100mm, the water flow rate is 70m 3 / h, when the casting length is 800mm, the water flow rate is 80m 3 / h until casting is completed; Casting speed: When the casting length is 0mm, the casting speed is 47mm / min; when the casting length is 50mm, the casting speed is 45mm / min; when the casting length is 200mm, the casting speed is 51mm / min until casting is completed; Crystallizer filling: When the casting height is 0mm, the crystallizer filling rate is 85mm / min; when the casting height is 15mm, the crystallizer filling rate is 75mm / min; when the casting height is 30mm, the crystallizer filling rate is 65mm / min; when the casting height is 60mm, the crystallizer filling rate is 55mm / min; Casting temperature: The aluminum liquid temperature at the end of the flow plate is 690-715℃; Cooling water temperature: 28℃;

[0128] Heat treatment: The cast aluminum alloy ingot is immediately subjected to heat treatment to obtain an aluminum alloy square ingot; wherein, the heat treatment has a heating rate of 50°C / h, a heating time of 10h, a holding temperature of 465°C, and a holding time of 36h.

[0129] The above ingots were machined and tested, and the oxide film of the ingots was greater than level 1, and was a level 3 waste.

[0130] The aluminum alloy square ingots obtained above were subjected to quality inspection:

[0131] (1) Ingot low magnification: Grain size is level 2; Oxide film is greater than level 1, level 3 scrap; The test method is GB / T3246.2 "Deformed aluminum and aluminum alloy products microstructure test method - Part 2 macrostructure test method";

[0132] (2) Chemical composition: Si 0.04%, Fe 0.11%, Cu 0.37%, Mn 0.42%, Cr 0.17%, Mg 3.16%, Zn 7.28%, Ti 0.05%, Zr 0.12%, Be 10 ppm; the detection method is GB / T 20975 "Analysis Method of Aluminum Alloys" and GB / T 7999 "Photoelectric Direct Reading Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloys";

[0133] (3) Hydrogen content: 0.11 mL / 100 g Al; the detection method is YS / T600 "Liquid Hydrogen Determination Method for Aluminum and Aluminum Alloys - Closed Circuit Method".

[0134] Comparative Example 3

[0135] The Al-Mg-Zn aluminum alloy is prepared in the following steps: ingot specification selection, raw material selection, smelting process, melt purification, grain refinement, casting control, and soaking treatment. The specific process is as follows:

[0136] Ingot specification selection: Ingot specification 400×1620mm;

[0137] Raw material selection: select the following raw materials according to the composition ratio of the aluminum alloy and make batching to obtain alloy raw materials: Al99.70 grade original aluminum ingot, Al99.9 grade magnesium ingot, Al99.99 grade zinc ingot, AlCu, AlMn, AlCr, AlBe, AlZr, AlTi master alloys produced from original aluminum ingots with a grade not lower than Al99.70, and first-level scrap batching;

[0138] Melting process: After the alloy raw materials are melted, samples are taken for analysis; the melting temperature in the furnace is 753°C, and the melt composition is adjusted to the control range according to the element matching requirements;

[0139] Melt purification: After the composition is adjusted, the melt in the furnace is refined using high-purity argon at a temperature of 748°C for 40 minutes. The melt is then refined using high-purity argon in a rotary degassing device, achieving a hydrogen content of 0.12 mL / 100 g Al. After online degassing, the melt is filtered using a 30+50 ppi ceramic foam filter plate.

[0140] Grain refinement: AlTi5B1 wire was used for grain refinement online, with a dosage of 1.0 kg / t;

[0141] Casting control: Aluminum base, no bottom, and wiper casting. Water flow: When the casting length is 0mm, the water flow is 80m 3 / h, when the casting length is 100mm, the water flow rate is 70m 3 / h, when the casting length is 800mm, the water flow rate is 80m 3 / h until casting is completed; Casting speed: When the casting length is 0mm, the casting speed is 47mm / min; when the casting length is 50mm, the casting speed is 45mm / min; when the casting length is 200mm, the casting speed is 51mm / min until casting is completed; Crystallizer filling: When the casting height is 0mm, the crystallizer filling rate is 85mm / min; when the casting height is 15mm, the crystallizer filling rate is 75mm / min; when the casting height is 30mm, the crystallizer filling rate is 65mm / min; when the casting height is 60mm, the crystallizer filling rate is 55mm / min; Casting temperature: The aluminum liquid temperature at the end of the flow plate is 690-715℃; Cooling water temperature: 26℃;

[0142] Heat treatment: The aluminum alloy ingot obtained by casting is immediately subjected to heat treatment, wherein the heating rate of the heat treatment is 50°C / h, the heating time is 10h, the holding temperature is 465°C, and the holding time is 36h.

[0143] The Al-Mg-Zn aluminum alloy plates obtained by machining, milling, rolling, solution quenching, aging treatment, flaw detection and packaging the above ingots are scrapped if the plate is below the standard.

[0144] The aluminum alloy square ingots and aluminum alloy plates obtained above were subjected to quality inspection:

[0145] (1) Macroscopic examination of ingot: grain size 1.5; oxide film meets the requirements of grade 1; the test method is GB / T3246.2 "Test methods for microstructure of wrought aluminum and aluminum alloy products - Part 2 Macroscopic examination method";

[0146] (2) Chemical composition: Si 0.04%, Fe 0.08%, Cu 0.18%, Mn 0.45%, Cr 0.16%, Mg 2.70%, Zn 6.90%, Ti 0.05%, Zr 0.11%, Be 10 ppm; the detection method is GB / T 20975 "Analysis Method of Aluminum Alloys" and GB / T 7999 "Photoelectric Direct Reading Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloys";

[0147] (3) Hydrogen content: 0.12 mL / 100 g Al; the detection method is YS / T600 "Liquid Hydrogen Determination Method for Aluminum and Aluminum Alloys - Closed Circuit Method";

[0148] (4) Plate flaw detection: in compliance with Class A; the testing method is GB / T 6519 “Ultrasonic testing method for deformed aluminum and magnesium alloy products”;

[0149] (5) Mechanical properties: T6 state performance, tensile strength 582 MPa, yield strength 535 MPa, elongation 9%; the test method is GB / T 16865 "Test specimens and methods for tensile testing of deformed aluminum, magnesium and their alloy products".

[0150] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0151] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily 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 is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A casting process for an Al-Mg-Zn aluminum alloy, comprising: Casting the grain-refined Al-Mg-Zn aluminum alloy melt, wherein no bottom is laid, no wiper is used, and a cast iron base is used during the casting process; The water flow rate of the casting is specifically: when the casting length is 0mm, the water flow rate is 60-100m 3 / h, when the casting length is 100mm, the water flow rate is 50~90m 3 / h, when the casting length is 800mm, the water flow rate is 60~100m 3 / h until casting is completed; The casting speed is specifically as follows: when the casting length is 0 mm, the casting speed is 42 to 55 mm / min; when the casting length is 50 mm, the casting speed is 40 to 53 mm / min; when the casting length is 200 mm, the casting speed is 42 to 55 mm / min; The crystallizer filling rate of the casting is specifically: when the casting height is 0 mm, the crystallizer filling rate is 70-100 mm / min, when the casting height is 15 mm, the crystallizer filling rate is 60-90 mm / min, when the casting height is 30 mm, the crystallizer filling rate is 50-80 mm / min, and when the casting height is 60 mm, the crystallizer filling rate is 40-70 mm / min.

2. The casting process according to claim 1, characterized in that The temperature of the aluminum liquid at the end of the casting flow plate is 690-715°C, and / or the temperature of the cooling water during the casting is 24-30°C.

3. The casting process according to any one of claims 1 to 2, characterized in that: The composition of the Al-Mg-Zn aluminum alloy, in percentage by mass, includes: Cu 0.20-0.60%, Mn 0.30-0.70%, Mg 2.8-3.5%, Cr 0.10-0.20%, Zn 7.0-8.0%, Ti 0.03-0.10%, Zr 0.05-0.15%, Be 5-20ppm, Si≤0.12%, Fe≤0.15%, and the balance is Al.

4. A method for preparing an Al-Mg-Zn aluminum alloy square ingot, comprising the following steps: According to the composition ratio of Al-Mg-Zn aluminum alloy square ingot, the raw materials after mixing are melted and the composition is adjusted; The melt after composition adjustment is melt purified and then subjected to grain refinement; Casting the melt after grain refinement to obtain an initial aluminum alloy square ingot, wherein the casting is the casting process according to any one of claims 1 to 3; The initial aluminum alloy square ingot is subjected to a soaking treatment.

5. The preparation method according to claim 4, characterized in that The melting temperature is 720-770°C.

6. The preparation method according to claim 4, characterized in that The melt purification includes refining, online degassing and melt filtration performed in sequence. The refining temperature is 720-750°C and the time is 30-50 minutes. The refining atmosphere is high-purity argon. The online degassing atmosphere is high-purity argon. After the online degassing, the hydrogen content of the melt is ≤0.15ml / 100gAl. The melt filtration adopts a ceramic filter plate with a ≥50ppi.

7. The preparation method according to claim 4, characterized in that The grain refining agent is Al-5Ti-1B wire, and the amount of the Al-5Ti-1B wire used is 0.8-1.2 kg / t melt.

8. The preparation method according to claim 4, characterized in that The soaking treatment is performed at a heating rate of 40-60°C / h and a heating time of 8-12h. The temperature is raised to 480-500°C, and the holding temperature is 460-475°C and the holding time is 30-40h.

9. The preparation method according to any one of claims 4 to 8, characterized in that The thickness of the aluminum alloy square ingot is 400-450 mm.

10. The preparation method according to any one of claims 4 to 8, characterized in that: Calculated by mass percentage, the aluminum alloy square ingot includes: Cu 0.20-0.60%, Mn 0.30-0.70%, Mg 2.8-3.5%, Cr 0.10-0.20%, Zn 7.0-8.0%, Ti 0.03-0.10%, Zr 0.05-0.15%, Be 5-20ppm, Si≤0.12%, Fe≤0.15%, and the balance is Al.