Preparation method of 7a09 aluminum alloy oversize round ingot

Abstract

The present application relates to the technical field of alloy, in particular to a preparation method of 7A09 aluminum alloy super-large specification round ingot.The preparation method of 7A09 aluminum alloy super-large specification round ingot provided by the present application comprises the following steps: sequentially performing dosing, smelting and composition adjustment, melt purification, grain refinement, casting and soaking treatment, and through controlling the process conditions of each step, especially the conditions of the casting process and the soaking conditions, the ingot forming, grain size, segregation layer depth and hydrogen content (≤0.12 mL / 100 g Al) can be stably controlled, so that the quality requirements of large-scale products are met.The ingot produced according to the process parameters of the present application has good forming effect and surface quality, high uniformity and stability of the structure;the ingot of the present application has large specification, can meet the demand of large-scale integral products, improve the overall performance of the products and reduce the process and cost;in addition, the operation of the present application is simple and clear, and the on-site executability is high.

Description

Technical Field

[0001] This invention relates to the field of alloy technology, and in particular to a method for preparing ultra-large-sized round ingots of 7A09 aluminum alloy. Background Technology

[0002] Al-Zn-Cu-Mg alloys are generally known as ultra-high-strength aluminum alloys. Due to their excellent processing properties, weldability, corrosion resistance, and toughness, they are widely used in the aerospace field and are considered one of the most important structural materials in this field. Aluminum alloy products are trending towards larger sizes. Currently, large-scale products are mainly produced using riveting and welding methods. To improve overall product performance and reduce processes and costs, large-scale products are moving towards integrated designs, requiring larger ingots to meet product demands.

[0003] For Al-Zn-Cu-Mg alloys, the ingot diameter is generally no more than 700mm. However, to meet the demands of large or monolithic products, ingot diameters of 1100mm are required. However, for high-strength, high-hardness wrought aluminum alloys in the Al-Zn-Cu-Mg series, the difficulty of controlling ingot forming, melt purity (hydrogen content), and microstructure uniformity increases exponentially with the increase in diameter. Currently, there is no production process for ultra-large Al-Zn-Cu-Mg aluminum alloy round ingots with a diameter of 1100mm; there are no successful precedents in China. Existing aluminum alloy casting technologies are insufficient to guarantee the forming and metallurgical quality requirements of the ingots. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing ultra-large 7A09 aluminum alloy round ingots. The present invention can successfully produce ultra-large Al-Zn-Cu-Mg aluminum alloy round ingots with a diameter of 1100mm, while ensuring the purity of the melt and the uniformity of the microstructure.

[0005] This invention provides a method for preparing ultra-large 7A09 aluminum alloy round ingots, comprising:

[0006] S1. Ingredients:

[0007] The raw materials are proportioned according to the target alloy composition;

[0008] in,

[0009] The target alloy comprises, by weight percentage:

[0010] Si: ≤0.10%;

[0011] Fe: Si content +0.08% < Fe ≤ 0.30%;

[0012] Cu: 1.20%~1.80%;

[0013] Mn: ≤0.05%;

[0014] Mg: 2.00%~3.00%;

[0015] Cr: 0.16%~0.30%;

[0016] Zn: 5.10%~6.10%;

[0017] Ti: ≤0.10%;

[0018] The balance consists of Al and unavoidable impurities;

[0019] The raw materials include: aluminum ingots, master alloys, pure metals, and primary waste.

[0020] S2, Smelting and Composition Adjustment:

[0021] The raw materials are melted, sampled, analyzed, and their composition is adjusted to obtain an alloy melt;

[0022] S3, Melt purification:

[0023] The alloy melt obtained in step S2 is refined in a furnace, then degassed and refined online, and then filtered to obtain a purified melt.

[0024] S4. Grain refinement:

[0025] Grain refinement was achieved using Al-5Ti-1B wire;

[0026] S5, Casting:

[0027] Pure aluminum is used to lay the bottom of the crystallizer, and then the aluminum liquid obtained in step S4 is introduced to fill the crystallizer, and then the casting is started.

[0028] in,

[0029] The purity of the aluminum is Al 99.70% or higher;

[0030] The length of the casting is >1000mm;

[0031] The casting conditions are as follows:

[0032] ① Cooling water temperature: 22~28℃;

[0033] ② Casting speed: When the casting length is < 600 mm, 10 mm / min ≤ casting speed ≤ 12 mm / min; when the casting length is 600 mm ≤ casting length < 1000 mm, 12 mm / min < casting speed ≤ 14 mm / min; when the casting length is ≥ 1000 mm, 14 mm / min < casting speed ≤ 17 mm / min.

[0034] ③ Water flow rate: When the casting length is <100mm, the water flow rate is 50~70m³ / h. 3 / h; when the casting length is 100mm ≤ casting length < 500m, the water flow rate is 40~60m. 3 / h; when the casting length is 500mm ≤ casting length < 700m, the water flow rate is 30~50m³ / h. 3 / h; when the casting length is ≥700mm, the water flow rate is 20~30m³ / h. 3 / h;

[0035] ④ Temperature at the end of the casting plate: When the casting length is <100mm, the temperature at the end of the casting plate is 675~690℃; when the casting length is 100mm≤300m, the temperature at the end of the casting plate is 680~690℃; when the casting length is 300mm≤500m, the temperature at the end of the casting plate is 685~700℃; when the casting length is ≥500mm, the temperature at the end of the casting plate is 690~705℃.

[0036] S6. Soaking heat treatment:

[0037] The ingot obtained in step S5 is subjected to homogenization heat treatment to obtain an ultra-large 7A09 aluminum alloy round ingot.

[0038] Preferably, in step S5, the pure aluminum is molten aluminum formed from aluminum ingots with an Al grade of 99.70% or higher;

[0039] The temperature of the bottom aluminum is 730~760℃, the filling time of the bottom aluminum is 150~250s, and the thickness of the bottom aluminum is ≥50mm;

[0040] The filling time is 300~400s.

[0041] Preferably, in step S5, a scraper is used during the casting process, with an initial scraping length of ≥400mm and a scraper height of 150~300mm.

[0042] Preferably, in step S6, the conditions for the homogenization heat treatment are as follows: ingot loading temperature ≤150℃, ingot heating rate 10~30℃ / h, holding temperature 460~480℃, and holding time ≥50h.

[0043] Preferably, in step S3, the alloy melt obtained in step S2 is refined in a furnace using a mixture of Ar and Cl2 gas; wherein the volume percentage of Ar in the mixture is 94% to 97%.

[0044] Preferably, in step S3, the refining temperature in the furnace is 740~760℃, and the time is ≥30min.

[0045] Preferably, in step S3, an online degassing and refining process is performed using a mixture of Ar and Cl2 gas; wherein the volume percentage of Ar in the mixture is 96% to 99%.

[0046] The online degassing rotor speed for the online degassing refining process is 200~400 rpm;

[0047] During the online degassing and refining process, the temperature of the online degassing chamber is 725~745℃.

[0048] Preferably, in step S4, the amount of Al-5Ti-1B wire used is 1.5 to 2.5 kg / t.

[0049] Preferably, in step S2, the melting temperature is 720~760℃;

[0050] The composition adjustment includes: comparing the actual chemical composition analysis results before the furnace with the target value; if the element content is lower than the target value, adding intermediate alloys containing the element until the target value is reached; if the element content exceeds the target value, adding aluminum ingots into the furnace to reduce the excess element to the target value.

[0051] Preferably, in step S3, the filter plate used for filtration has an accuracy of 50 ppi or higher;

[0052] The temperature of the filter basin used in the filtration process is 715~730℃;

[0053] The diameter of the 7A09 aluminum alloy extra-large round ingot is >1000mm.

[0054] The present invention provides a method for preparing ultra-large-sized round ingots of 7A09 aluminum alloy, which involves sequentially performing batching, smelting and composition adjustment, melt purification, grain refinement, casting, and homogenization. By controlling the process conditions of each step, especially the casting and homogenization conditions, the ingot forming, grain size, segregation layer depth, and hydrogen content ≤0.12mL / 100gAl can be stably controlled, meeting the quality requirements of large-scale products. Therefore, the ingots produced according to the process parameters of the present invention have good forming effect and surface quality, and high microstructure uniformity and stability. The large ingot size of the present invention can meet the needs of large-scale integral products, improve the overall performance of the product, and reduce process and cost. In addition, the present invention is simple and clear to operate, and has high on-site feasibility.

[0055] The experimental results show that the quality of the ingots obtained by this invention is as follows: grain size ≤ grade 2, segregation layer depth ≤ 35 mm; H content ≤ 0.12 mL / 100 g Al. Attached Figure Description

[0056] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0057] Figure 1 This is a microstructure diagram of the ingot core obtained in Embodiment 1 of the present invention, wherein, Figure 1 (a)- Figure 1 (b) are tissue morphology images at different magnifications. Detailed Implementation

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0059] In this article, the technical features described in an open-ended manner include both closed technical solutions composed of the listed features and open technical solutions that include the listed features.

[0060] As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items.

[0061] In this document, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when a range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0062] In this article, when referring to units for data ranges, if the unit is only followed by the right endpoint, it indicates that the units for the left and right endpoints are the same. For example, 675~690℃ means that the units for the left endpoint "675" and the right endpoint "690" are both in degrees Celsius (℃).

[0063] This invention provides a method for preparing ultra-large 7A09 aluminum alloy round ingots, comprising:

[0064] S1. Ingredients:

[0065] The raw materials are proportioned according to the target alloy composition;

[0066] in,

[0067] The target alloy comprises, by weight percentage:

[0068] Si: ≤0.10%;

[0069] Fe: Si content +0.08% < Fe ≤ 0.30%;

[0070] Cu: 1.20%~1.80%;

[0071] Mn: ≤0.05%;

[0072] Mg: 2.00%~3.00%;

[0073] Cr: 0.16%~0.30%;

[0074] Zn: 5.10%~6.10%;

[0075] Ti: ≤0.10%;

[0076] The balance consists of Al and unavoidable impurities;

[0077] The raw materials include: aluminum ingots, master alloys, pure metals, and primary waste.

[0078] S2, Smelting and Composition Adjustment:

[0079] The raw materials are melted, sampled, analyzed, and their composition is adjusted to obtain an alloy melt;

[0080] S3, Melt purification:

[0081] The alloy melt obtained in step S2 is refined in a furnace, then degassed and refined online, and then filtered to obtain a purified melt.

[0082] S4. Grain refinement:

[0083] Grain refinement was achieved using Al-5Ti-1B wire;

[0084] S5, Casting:

[0085] Pure aluminum is used to lay the bottom of the crystallizer, and then the aluminum liquid obtained in step S4 is introduced to fill the crystallizer, and then the casting is started.

[0086] in,

[0087] The purity of the aluminum is Al 99.70% or higher;

[0088] The length of the casting is >1000mm;

[0089] The casting conditions are as follows:

[0090] ① Cooling water temperature: 22~28℃;

[0091] ② Casting speed: When the casting length is < 600 mm, 10 mm / min ≤ casting speed ≤ 12 mm / min; when the casting length is 600 mm ≤ casting length < 1000 mm, 12 mm / min < casting speed ≤ 14 mm / min; when the casting length is ≥ 1000 mm, 14 mm / min < casting speed ≤ 17 mm / min.

[0092] ③ Water flow rate: When the casting length is <100mm, the water flow rate is 50~70m³ / h. 3 / h; when the casting length is 100mm ≤ casting length < 500m, the water flow rate is 40~60m. 3 / h; when the casting length is 500mm ≤ casting length < 700m, the water flow rate is 30~50m³ / h. 3 / h; when the casting length is ≥700mm, the water flow rate is 20~30m³ / h. 3 / h;

[0093] ④ Temperature at the end of the casting plate: When the casting length is <100mm, the temperature at the end of the casting plate is 675~690℃; when the casting length is 100mm≤300m, the temperature at the end of the casting plate is 680~690℃; when the casting length is 300mm≤500m, the temperature at the end of the casting plate is 685~700℃; when the casting length is ≥500mm, the temperature at the end of the casting plate is 690~705℃.

[0094] S6. Soaking heat treatment:

[0095] The ingot obtained in step S5 is subjected to homogenization heat treatment to obtain an ultra-large 7A09 aluminum alloy round ingot.

[0096] Regarding step S1 :

[0097] S1. Batching: Batching the raw materials according to the target alloy composition.

[0098] In this invention, the target alloy comprises, by mass percentage:

[0099] Si: ≤0.10%;

[0100] Fe: Si content +0.08% < Fe ≤ 0.30%;

[0101] Cu: 1.20%~1.80%;

[0102] Mn: ≤0.05%;

[0103] Mg: 2.00%~3.00%;

[0104] Cr: 0.16%~0.30%;

[0105] Zn: 5.10%~6.10%;

[0106] Ti: ≤0.10%;

[0107] The margin is Al.

[0108] Specifically, the Si content can be 0.04%, 0.05%, etc. The Fe content is ≤0.30% and >Si content +0.08%, specifically 0.16%, 0.17%, 0.22%, etc. The Cu content can be 1.20%, 1.30%, 1.40%, 1.50%, 1.58%, 1.60%, 1.65%, 1.70%, 1.80%, etc. The Mn content can be 0.01%, 0.02%, etc. The Mg content can be 2.00%, 2.10%, 2.20%, 2.30%, 2.35%, 2.40%, 2.50%, 2.60%, 2.70%, 2.80%, 2.90%, 3.00%, etc. The specific Cr content can be 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, etc. The specific Zn content can be 5.10%, 5.20%, 5.30%, 5.40%, 5.50%, 5.60%, 5.66%, 5.70%, 5.71%, 5.80%, 5.82%, 5.90%, 6.00%, 6.10%, etc. The specific Ti content can be 0.03%, etc.

[0109] In some embodiments of the present invention, the chemical composition of the alloy is: Si 0.05%, Fe 0.17%, Cu 1.58%, Mn 0.02%, Mg 2.35%, Cr 0.18%, Zn 5.66%, Ti 0.03%, Be 9ppm, Na 3ppm, with Al as the balance. In some embodiments of the present invention, the chemical composition of the alloy is: Si 0.05%, Fe 0.22%, Cu 1.65%, Mn 0.02%, Mg 2.40%, Cr 0.19%, Zn 5.71%, Ti 0.03%, Be 11ppm, Na 2ppm, with Al as the balance.

[0110] The raw materials used in this invention include: aluminum ingots, master alloys, pure metals, and primary waste. Preferably, the aluminum ingots are primary aluminum ingots with an Al content of 99.70% or higher. The master alloys include AlCu master alloys, AlCr master alloys, and AlTi master alloys. The pure metals include Cu plates, Mg ingots, and Zn ingots. This invention does not impose any special restrictions on the type and source of the primary waste; any primary waste commonly used in aluminum alloy manufacturing processes in this field is acceptable. Preferably, the raw materials also include additives. The additives are preferably Cr additives.

[0111] Regarding step S2 :

[0112] S2. Melting and Composition Adjustment: Melt the raw materials, take samples for analysis and adjust the composition to obtain the alloy melt.

[0113] In this invention, the preferred melting temperature is 720~760℃, specifically 720℃, 725℃, 730℃, 735℃, 740℃, 745℃, 750℃, 751℃, 755℃, and 760℃. During the melting process, stirring is preferably performed simultaneously; the stirring is both electromagnetic stirring and mechanical stirring.

[0114] In this invention, after stirring, sampling analysis and composition adjustment are also performed. Specifically, the actual chemical composition analysis results before the furnace are compared with the expected target value. If the element content is lower than the target value, a certain amount of intermediate alloy containing the element is added until the target value is reached. If the element content exceeds the target value, aluminum ingots are added to the furnace to reduce the excess element to the target value.

[0115] Regarding step S3 :

[0116] S3. Melt purification: The alloy melt obtained in step S2 is refined in a furnace, then degassed and refined online, and finally filtered to obtain purified melt.

[0117] In this invention, preferably, the alloy melt obtained in step S2 is refined in a furnace using a mixed gas of Ar + Cl2. The volume percentage of Ar (argon) in the mixed gas is 94%~97%, specifically 94%, 95%, 96%, or 97%. The furnace refining temperature is 740~760℃, specifically 740℃, 745℃, 748℃, 750℃, 751℃, 752℃, 755℃, or 760℃. The furnace refining time is ≥30 min, preferably 30~60 min, specifically 30 min, 40 min, or 60 min. In this invention, after the above furnace refining, the liquid hydrogen content of the resulting melt is ≤0.25 mL / 100gAl.

[0118] In this invention, after the above-mentioned in-furnace refining, the melt obtained from in-furnace refining is subjected to online degassing refining; specifically, online degassing refining is performed using a rotary degassing device. Preferably, an Ar+Cl2 mixed gas is used for online degassing refining. The volume percentage of Ar (argon) in the mixed gas is 96%~99%, specifically 96%, 97%, 98%, or 99%. The flow rate of Ar is 3~5 Nm³. 3 / h, specifically 3Nm 3 / h、4Nm 3 / h、5Nm 3 / h. In this invention, the online degassing and refining process involves an online degassing rotor speed of 200~400 rpm, specifically 200 rpm, 250 rpm, 300 rpm, 350 rpm, or 400 rpm. The online degassing chamber temperature during the online degassing and refining process is 725~745℃, specifically 725℃, 730℃, 732℃, 734℃, 735℃, 738℃, 740℃, or 745℃. After the above online degassing and refining process, the liquid hydrogen content of the resulting melt is ≤0.12 mL / 100gAl.

[0119] In this invention, after the above-mentioned online degassing and refining, filtration is performed. The filtration is online filtration. There are no special limitations on the filtration device used; any conventional filtration device in the art is acceptable, generally including a filter basin for the flow of molten aluminum and a filter plate for filtering the molten aluminum. In this invention, the filter plate used is preferably a ceramic plate. The filter plate's precision is preferably 50 ppi or higher. In some embodiments of this invention, a 40+60 ppi foam ceramic filter plate is used. In this invention, the temperature of the filter basin used for filtration is 715~730℃, specifically 715℃, 720℃, 724℃, 725℃, 727℃, 730℃, etc.

[0120] Regarding step S4 :

[0121] S4. Grain refinement: Grain refinement is performed using Al-5Ti-1B wire.

[0122] In this invention, after filtration in step S3, the melt is subjected to online grain refinement using Al-5Ti-1B wire. The amount of Al-5Ti-1B wire used in this invention is 1.5–2.5 kg / t, and the Ti content before the furnace is supplemented to 0.02%. Specifically, the amount of Al-5Ti-1B wire used can be 1.5 kg / t, 1.6 kg / t, 1.7 kg / t, 1.8 kg / t, 1.9 kg / t, 2.0 kg / t, 2.1 kg / t, 2.2 kg / t, 2.3 kg / t, 2.4 kg / t, or 2.5 kg / t.

[0123] Regarding step S5 :

[0124] S5. Casting: Pure aluminum is used to lay the bottom of the crystallizer, and then the aluminum liquid obtained in step S4 is introduced to fill the crystallizer. Then the casting is started.

[0125] In this invention, pure aluminum is first used to pave the bottom of the crystallizer. The pure aluminum is molten aluminum formed from aluminum ingots with an Al content of 99.70% or higher. The temperature of the molten aluminum lining is 730~760℃, specifically 730℃, 735℃, 740℃, 745℃, 750℃, 753℃, 755℃, 760℃, etc. The filling time of the molten aluminum lining is 150~250s, specifically 150s, 160s, 170s, 180s, 190s, 200s, 210s, 220s, 230s, 240s, 250s, etc. The thickness of the molten aluminum lining is ≥50mm, preferably 50~65mm, specifically 50mm, 60mm, 65mm.

[0126] In this invention, after the aforementioned base layering, the molten aluminum obtained in step S4 is introduced into the crystallizer to fill it. Specifically, immediately after the base layering is completed, the gate is opened and the main metal (i.e., the molten aluminum obtained in step S4) is introduced for filling. In this invention, the filling time is 300-400 seconds, specifically 300s, 310s, 320s, 330s, 340s, 350s, 360s, 370s, 371s, 380s, 390s, or 400s. After the crystallizer is filled, casting is started.

[0127] In this invention, the target diameter of the casting is >1000mm, and in some embodiments of this invention it is 1100mm (i.e., Φ1100mm). In this invention, the length of the casting is >1000mm.

[0128] In this invention, to prevent the ingot from cracking at the bottom and during the casting process, specific casting process parameters are controlled. The casting conditions are as follows: ①-④

[0129] ① Cooling water temperature: 22~28℃; specifically, it can be 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, or 28℃.

[0130] ② Casting speed: When the casting length is < 600 mm, 10 mm / min ≤ casting speed ≤ 12 mm / min; when the casting length is 600 mm ≤ casting length < 1000 mm, 12 mm / min < casting speed ≤ 14 mm / min; when the casting length is ≥ 1000 mm, 14 mm / min < casting speed ≤ 17 mm / min.

[0131] That is, during the casting process, the casting speed is controlled separately in different casting sections:

[0132] When the casting length is less than 600mm (meaning from the start of casting until the casting length is less than 600mm, i.e., during the casting length from 0mm to 600mm), the casting speed should be 10mm / min ≤ casting speed ≤ 12mm / min, specifically 10mm / min, 11mm / min, 12mm / min, etc.

[0133] When the casting length is between 600mm and 1000mm (meaning from the time the casting length reaches 600mm until it reaches 1000mm, i.e., during the casting length of 600-1000mm), the casting speed is between 12mm / min and 14mm / min, specifically 13mm / min, 14mm / min, etc.

[0134] When the casting length is ≥1000mm (meaning from the time the casting length reaches 1000mm until the casting is completed), the casting speed should be 14mm / min < casting speed ≤17mm / min, specifically 15mm / min, 16mm / min, 17mm / min, etc.

[0135] ③ Water flow rate: When the casting length is <100mm, the water flow rate is 50~70m³ / h. 3 / h; when the casting length is 100mm ≤ casting length < 500m, the water flow rate is 40~60m. 3 / h; when the casting length is 500mm ≤ casting length < 700m, the water flow rate is 30~50m³ / h. 3 / h; when the casting length is ≥700mm, the water flow rate is 20~30m³ / h. 3 / h.

[0136] That is, during the casting process, the water flow is controlled separately in different casting sections:

[0137] When the casting length is <100mm (meaning from the start of casting until the casting length reaches 100mm, i.e., during the casting length from 0mm to 100mm), the water flow rate is 50~70m³ / h. 3 / h, specifically 50m 3 / h、55m 3 / h、60m 3 / h、65m 3 / h、70m 3 / h etc.

[0138] When the casting length is between 100mm and 500mm (meaning from the time the casting length reaches 100mm until it reaches 500mm, i.e., during the casting length of 100-500mm), the water flow rate is 40-60m³ / h. 3 / h, specifically 40m 3 / h、43m 3 / h, 45m 3 / h, 50m 3 / h、55m 3 / h、60m 3 / h etc.

[0139] When the casting length is between 500mm and 700mm (meaning from the time the casting length reaches 500mm until it reaches 700mm, i.e., during the casting length of 500-700mm), the water flow rate is 30-50m³ / h. 3 / h, specifically 30m 3 / h, 35m 3 / h, 40m 3 / h, 45m 3 / h, 50m 3 / h etc.

[0140] When the casting length is ≥700mm (meaning from the time the casting length reaches 700mm until the casting is completed), the water flow rate is 20~30m³ / h. 3 / h, specifically 20m 3 / h、22m 3 / h, 25m 3 / h, 30m 3 / h etc.

[0141] ④ Temperature at the end of the casting plate: When the casting length is <100mm, the temperature at the end of the casting plate is 675~690℃; when the casting length is 100mm≤300m, the temperature at the end of the casting plate is 680~690℃; when the casting length is 300mm≤500m, the temperature at the end of the casting plate is 685~700℃; when the casting length is ≥500mm, the temperature at the end of the casting plate is 690~705℃.

[0142] That is, during the casting process, the temperature at the end of the casting plate is controlled separately in different casting sections:

[0143] When the casting length is <100mm (meaning from the start of casting until the casting length is less than 100mm, i.e., during the casting length from 0mm to 100mm), the temperature at the end of the runner is 675~690℃, specifically 675℃, 678℃, 680℃, 682℃, 685℃, 690℃, etc.

[0144] When the casting length is between 100mm and 300mm (meaning from the time the casting length reaches 100mm until it reaches 300mm, i.e., during the casting length of 100~300mm), the temperature at the end of the runner is 680~690℃, specifically 680℃, 683℃, 685℃, 687℃, 689℃, 690℃, etc.

[0145] When the casting length is 300mm≤casting length<500mm (meaning from the casting length from 100mm to 500mm, i.e., during the casting length of 100~500mm), the temperature at the end of the runner is 685~700℃, specifically 685℃, 687℃, 690℃, 691℃, 695℃, 700℃, etc.

[0146] When the casting length is ≥500mm (meaning from the time the casting length reaches 500mm until the casting is completed), the temperature at the end of the runner is 690~705℃, specifically 690℃, 693℃, 695℃, 699℃, 700℃, 705℃, etc.

[0147] In this invention, a wiper is used during the casting process. The initial wiping length is ≥400mm (i.e., wiping begins when the casting length reaches 400mm or more and continues until the casting is completed), preferably 400~600mm, specifically 400mm, 450mm, 500mm, 550mm, or 600mm. The height of the wiper is 150~300mm, specifically 150mm, 160mm, 170mm, 180mm, 190mm, 200mm, 210mm, 220mm, 230mm, 240mm, 250mm, 260mm, 270mm, 280mm, 290mm, or 300mm. Specifically, for air-filled or water-filled wipers, the initial wiping length is ≥400mm, and the wiper height is 150~300mm. For integral rubber wipers, the height is 150~300mm.

[0148] Regarding step S6 :

[0149] S6. Homogenization heat treatment: The ingot obtained in step S5 is subjected to homogenization heat treatment to obtain 7A09 aluminum alloy ultra-large round ingot.

[0150] In this invention, to eliminate ingot stress and reduce segregation and ensure sufficient re-dissolution of non-equilibrium crystalline phases, the ingot is subjected to homogenization heat treatment immediately after casting in step S5. The conditions for homogenization heat treatment are as follows: ingot loading temperature ≤150℃, ingot heating rate 10~30℃ / h, holding temperature 460~480℃, and holding time ≥50h. The ingot loading temperature is preferably 100~150℃, specifically 100℃, 120℃, or 150℃. The ingot heating rate can be specifically 10℃ / h, 15℃ / h, 20℃ / h, 25℃ / h, or 30℃ / h. The holding temperature can be specifically 460℃, 465℃, 470℃, 475℃, or 480℃. The holding time is preferably 50~60h, specifically 50h, 55h, or 60h. After the above heat treatment, the material is sawn; specifically, 500-600mm is cut from the gate and 300-600mm (preferably 500mm) from the bottom. This process yields a 7A09 aluminum alloy extra-large round ingot. The diameter of the 7A09 aluminum alloy extra-large round ingot is >1000mm, and in some embodiments of this invention, it is 1100mm (i.e., Φ1100mm).

[0151] In this invention, the quality of the obtained ingot is as follows: grain size ≤ grade 2, segregation layer depth ≤ 35 mm; H content ≤ 0.12 ml / 100 g Al.

[0152] The present invention provides a method for preparing ultra-large-sized round ingots of 7A09 aluminum alloy, which involves sequentially performing batching, smelting and composition adjustment, melt purification, grain refinement, casting, and homogenization. By controlling the process conditions of each step, especially the casting and homogenization conditions, the ingot forming, grain size, segregation layer depth, and hydrogen content ≤0.12mL / 100gAl can be stably controlled, meeting the quality requirements of large-scale products. Therefore, the ingots produced according to the process parameters of the present invention have good forming effect and surface quality, and high microstructure uniformity and stability. The large ingot size of the present invention can meet the needs of large-scale integral products, improve the overall performance of the product, and reduce process and cost. In addition, the present invention is simple and clear to operate, and has high on-site feasibility.

[0153] 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, and not for limiting the scope of the claims of the present invention.

[0154] Example 1

[0155] Ingot specifications: Ф1100mm × length 5000mm.

[0156] The preparation process is as follows:

[0157] S1. Ingredients:

[0158] The raw materials are batched according to the target alloy composition. The raw materials used include: 99.70% Al aluminum ingots, master alloys, pure metals, and primary waste.

[0159] S2, Smelting and Composition Adjustment:

[0160] After the alloy raw materials are completely melted, samples are taken for analysis; the melting temperature in the furnace is 740℃, and electromagnetic stirring and mechanical stirring are used simultaneously to treat the melt;

[0161] Composition adjustment: Based on the actual chemical composition analysis results before the furnace and the expected target value, if the element content is lower than the target value, add a certain amount of intermediate alloy containing the element until the target value is reached. If the element content exceeds the target value, add aluminum ingots into the furnace to reduce the excess element to the target value.

[0162] S3, Melt purification:

[0163] The furnace was used for refining with a mixture of Ar and Cl2 gas (Ar content 97%) for 30 minutes at a refining temperature of 748℃. The liquid hydrogen content of the melt obtained after furnace refining was 0.22 mL / 100 g Al. Then, the furnace was used for online refining with a mixture of Ar and Cl2 gas (Ar content 98%) for 40 minutes at an online degassing rotor speed of 300 rpm and an Ar flow rate of 5 Nm³. 3 The online degassing chamber temperature was 738℃, and the liquid hydrogen content of the melt obtained after online degassing and refining was 0.10mL / 100gAl. Subsequently, filtration was performed using a 40+60ppi foam ceramic filter plate, with the filter pan temperature maintained at 725℃ during the filtration process.

[0164] S4. Grain refinement:

[0165] Al-5Ti-1B wire was added to the melt to refine the grains at a rate of 2.0 kg / t.

[0166] S5, Casting:

[0167] First, pure aluminum (aluminum liquid formed from aluminum ingots with an Al content of 99.70% or higher, Si content of 0.05%, and Fe content of 0.12%) is used to lay the bottom layer of the crystallizer. The bottom layer aluminum melt temperature is 750℃, the bottom layer aluminum thickness is 65mm, and the bottom layer aluminum filling time is 190s.

[0168] After the base layer is laid, immediately open the gate and pour in the main body metal (i.e., the molten aluminum obtained in step S4) for filling, controlling the filling time to 380 seconds. After filling is completed, start casting.

[0169] Wiper parameters: starting wiping length 600mm, wiper height 240mm.

[0170] The casting conditions are as follows: ①-④

[0171] ① Cooling water temperature: 27℃;

[0172] ② Casting speed: When the casting length is < 600 mm, the casting speed is 12 mm / min; when the casting length is 600 mm ≤ casting length < 1000 mm, the casting speed is 14 mm / min; when the casting length is ≥ 1000 mm, the casting speed is 16 mm / min.

[0173] ③ Water flow rate: When the casting length is <100mm, the water flow rate is 60m³ / h. 3 / h; when the casting length is 100mm ≤ casting length < 500m, the water flow rate is 45m³ / h. 3 / h; when the casting length is 500mm ≤ casting length < 700m, the water flow rate is 40m³ / h. 3 / h; when the casting length is ≥700mm, the water flow rate is 25m³ / h. 3 / h.

[0174] ④ Temperature at the end of the casting plate: When the casting length is <100mm, the temperature at the end of the casting plate is 680℃; when the casting length is 100mm≤300m, the temperature at the end of the casting plate is 687℃; when the casting length is 300mm≤500m, the temperature at the end of the casting plate is 691℃; when the casting length is ≥500mm, the temperature at the end of the casting plate is 700℃.

[0175] After casting, an ingot is obtained, with dimensions of Ф1100mm × length of 5000mm.

[0176] S6. Soaking heat treatment:

[0177] The ingot obtained in step S5 was subjected to homogenization heat treatment under the following conditions: ingot loading temperature 120℃, ingot heating rate 25℃ / h, holding temperature 470℃, and holding time 60h. Afterwards, it was sawn, with 600mm cut from the gate and 500mm from the bottom, ultimately yielding a 7A09 aluminum alloy extra-large round ingot (Ф1100mm × length 3900mm).

[0178] Product detection :

[0179] Low-magnification results of the ingot: grain size grade 2, porosity grade 1, segregation layer 20 mm; the testing method was GB / T3246.2 "Methods for Inspection of Microstructure of Wrought Aluminum and Aluminum Alloy Products - Part 2: Low-Magnification Microstructure Inspection Methods". The microstructure morphology of the obtained ingot core is as follows. Figure 1 As shown, Figure 1 (a)- Figure 1 (b) are tissue morphology images (SEM images) at different magnifications.

[0180] Chemical composition: Si 0.05%, Fe 0.17%, Cu 1.58%, Mn 0.02%, Mg 2.35%, Cr 0.18%, Zn 5.66%, Ti 0.03%, Be 9ppm, Na 3ppm, balance Al; detection methods are GB / T 20975 "Analytical Methods for Aluminum Alloys" and GB / T 7999 "Direct Reading Photoelectric Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloys".

[0181] Liquid hydrogen content: 0.10 mL / 100 g Al; detection method is YS / T600 "Closed-loop circulation method for the determination of liquid hydrogen in aluminum and aluminum alloys".

[0182] Solid hydrogen content: 0.15 μg / g; detection method is GJB 5909 "Determination of hydrogen in aluminum and aluminum alloys by heating extraction and thermal conductivity method".

[0183] Example 2

[0184] Ingot specifications: Ф1100mm × length 5500mm.

[0185] The preparation process is as follows:

[0186] S1. Ingredients:

[0187] The raw materials are batched according to the target alloy composition. The raw materials used include: 99.70% Al aluminum ingots, master alloys, pure metals, and primary waste.

[0188] S2, Smelting and Composition Adjustment:

[0189] After the alloy raw materials are completely melted, samples are taken for analysis; the melting temperature in the furnace is 751℃, and electromagnetic stirring and mechanical stirring are used simultaneously to treat the melt;

[0190] Composition adjustment: Based on the actual chemical composition analysis results before the furnace and the expected target value, if the element content is lower than the target value, add a certain amount of intermediate alloy containing the element until the target value is reached. If the element content exceeds the target value, add aluminum ingots into the furnace to reduce the excess element to the target value.

[0191] S3, Melt purification:

[0192] The furnace was used for refining with a mixture of Ar and Cl2 gas (Ar content 97%) for 40 minutes at a refining temperature of 751℃. The liquid hydrogen content of the melt obtained after furnace refining was 0.23 mL / 100gAl. Then, the furnace was used for online refining with a mixture of Ar and Cl2 gas (Ar content 98%) for 40 minutes at an online degassing rotor speed of 300 rpm and an Ar flow rate of 5 Nm³. 3The online degassing chamber temperature was 734℃, and the liquid hydrogen content of the melt obtained after online degassing and refining was 0.11mL / 100gAl. Subsequently, filtration was performed using a 40+50ppi foam ceramic filter plate, with the filter pan temperature maintained at 727℃ during the filtration process.

[0193] S4. Grain refinement:

[0194] Al-5Ti-1B wire was added to the melt to refine the grains at a rate of 2.0 kg / t.

[0195] S5, Casting:

[0196] First, pure aluminum (aluminum liquid formed from aluminum ingots with an Al content of 99.70% or higher, Si content of 0.04%, and Fe content of 0.13%) is used to lay the bottom layer of the crystallizer. The bottom layer aluminum melt temperature is 753℃, the bottom layer aluminum thickness is 60mm, and the bottom layer aluminum filling time is 200s.

[0197] After the base layer is laid, immediately open the gate and pour in the main body metal (i.e., the molten aluminum obtained in step S4) for filling, controlling the filling time to 371 seconds. After filling is completed, start casting.

[0198] Wiper parameters: starting wiping length 550mm, wiper height 220mm.

[0199] The casting conditions are as follows: ①-④

[0200] ① Cooling water temperature: 26℃;

[0201] ② Casting speed: When the casting length is < 600 mm, the casting speed is 12 mm / min; when the casting length is 600 mm ≤ casting length < 1000 mm, the casting speed is 14 mm / min; when the casting length is ≥ 1000 mm, the casting speed is 16 mm / min.

[0202] ③ Water flow rate: When the casting length is <100mm, the water flow rate is 50m³ / h. 3 / h; when the casting length is 100mm ≤ casting length < 500m, the water flow rate is 45m³ / h. 3 / h; when the casting length is 500mm ≤ casting length < 700m, the water flow rate is 40m³ / h. 3 / h; when the casting length is ≥700mm, the water flow rate is 25m³ / h. 3 / h.

[0203] ④ Temperature at the end of the casting plate: When the casting length is <100mm, the temperature at the end of the casting plate is 678℃; when the casting length is 100mm≤300m, the temperature at the end of the casting plate is 683℃; when the casting length is 300mm≤500m, the temperature at the end of the casting plate is 687℃; when the casting length is ≥500mm, the temperature at the end of the casting plate is 693℃.

[0204] After casting, an ingot is obtained, with dimensions of Ф1100mm × length of 5500mm.

[0205] S6. Soaking heat treatment:

[0206] The ingot obtained in step S5 was subjected to homogenization heat treatment under the following conditions: ingot loading temperature 100℃, ingot heating rate 25℃ / h, holding temperature 470℃, and holding time 60h. Afterwards, it was sawn, with 600mm cut from the gate and 500mm from the bottom, ultimately yielding a 7A09 aluminum alloy extra-large round ingot (Ф1100mm × length 4400mm).

[0207] Product detection :

[0208] The various tests were performed according to the detection method in Example 1, and the results are as follows:

[0209] Low magnification results of the ingot: grain size grade 1.5, porosity grade 1, segregation layer 22mm.

[0210] Chemical composition: Si 0.05%, Fe 0.22%, Cu 1.65%, Mn 0.02%, Mg 2.40%, Cr 0.19%, Zn 5.71%, Ti 0.03%, Be 11ppm, Na 2ppm, balance Al.

[0211] Liquid hydrogen content: 0.11 mL / 100 g Al;

[0212] Solid hydrogen content: 0.15 μg / g.

[0213] Example 3

[0214] Ingot specifications: Ф1100mm × length 5000mm.

[0215] The preparation process is as follows:

[0216] S1. Ingredients:

[0217] The raw materials are batched according to the target alloy composition. The raw materials used include: 99.70% Al aluminum ingots, master alloys, pure metals, and primary waste.

[0218] S2, Smelting and Composition Adjustment:

[0219] After the alloy raw materials are completely melted, samples are taken for analysis; the melting temperature in the furnace is 750℃, and electromagnetic stirring and mechanical stirring are used simultaneously to treat the melt;

[0220] Composition adjustment: Based on the actual chemical composition analysis results before the furnace and the expected target value, if the element content is lower than the target value, add a certain amount of intermediate alloy containing the element until the target value is reached. If the element content exceeds the target value, add aluminum ingots into the furnace to reduce the excess element to the target value.

[0221] S3, Melt purification:

[0222] The furnace was used for refining with a mixture of Ar and Cl2 gas (Ar content 97%) for 60 minutes at a refining temperature of 752℃. The liquid hydrogen content of the melt obtained after furnace refining was 0.24 mL / 100gAl. Then, it was refined online with a mixture of Ar and Cl2 gas (Ar content 98%) for 40 minutes at an online degassing rotor speed of 300 rpm and an Ar flow rate of 5 Nm³. 3 The online degassing chamber temperature was 732℃, and the liquid hydrogen content of the melt obtained after online degassing and refining was 0.09mL / 100gAl. Subsequently, filtration was performed using a 40+60ppi foam ceramic filter plate, with the filter pan temperature maintained at 724℃ during the filtration process.

[0223] S4. Grain refinement:

[0224] Al-5Ti-1B wire was added to the melt to refine the grains at a rate of 2.2 kg / t.

[0225] S5, Casting:

[0226] First, pure aluminum (aluminum liquid formed from aluminum ingots with an Al content of 99.70% or higher, Si content of 0.05%, and Fe content of 0.12%) is used to lay the bottom layer of the crystallizer. The bottom layer aluminum melt temperature is 755℃, the bottom layer aluminum thickness is 65mm, and the bottom layer aluminum filling time is 210s.

[0227] After the base layer is laid, immediately open the gate and pour in the main body metal (i.e., the molten aluminum obtained in step S4) for filling, controlling the filling time to 371 seconds. After filling is completed, start casting.

[0228] Wiper parameters: starting wiping length 500mm, wiper height 210mm.

[0229] The casting conditions are as follows: ①-④

[0230] ① Cooling water temperature: 24℃;

[0231] ② Casting speed: When the casting length is < 600 mm, the casting speed is 12 mm / min; when the casting length is 600 mm ≤ casting length < 1000 mm, the casting speed is 14 mm / min; when the casting length is ≥ 1000 mm, the casting speed is 15 mm / min.

[0232] ③ Water flow rate: When the casting length is <100mm, the water flow rate is 50m³ / h. 3 / h; when the casting length is 100mm ≤ casting length < 500m, the water flow rate is 43m³ / h. 3 / h; when the casting length is 500mm ≤ casting length < 700m, the water flow rate is 40m³ / h. 3 / h; when the casting length is ≥700mm, the water flow rate is 22m³ / h. 3 / h.

[0233] ④ Temperature at the end of the casting plate: When the casting length is <100mm, the temperature at the end of the casting plate is 682℃; when the casting length is 100mm≤300m, the temperature at the end of the casting plate is 689℃; when the casting length is 300mm≤500m, the temperature at the end of the casting plate is 695℃; when the casting length is ≥500mm, the temperature at the end of the casting plate is 699℃.

[0234] After casting, an ingot is obtained, with dimensions of Ф1100mm × length of 5000mm.

[0235] S6. Soaking heat treatment:

[0236] The ingot obtained in step S5 was subjected to homogenization heat treatment under the following conditions: ingot loading temperature 150℃, ingot heating rate 25℃ / h, holding temperature 470℃, and holding time 60h. Afterwards, it was sawn, with 500mm cut from the gate and 500mm from the bottom, ultimately yielding a 7A09 aluminum alloy extra-large round ingot (Ф1100mm × length 3900mm).

[0237] Product detection :

[0238] The various tests were performed according to the detection method in Example 1, and the results are as follows:

[0239] Low magnification results of ingot casting: grain size grade 2, porosity grade 1, segregation layer 18mm.

[0240] Chemical composition: Si 0.04%, Fe 0.16%, Cu 1.60%, Mn 0.01%, Mg 2.20%, Cr 0.21%, Zn 5.82%, Ti 0.03%, Be 8ppm, Na 2ppm, balance Al.

[0241] Liquid hydrogen content: 0.09 mL / 100 g Al;

[0242] Solid hydrogen content: 0.12 μg / g.

[0243] Comparative Example 1

[0244] The process was carried out according to Example 1, except that the alloy composition was changed. The pre-furnace composition analysis is as follows: Si 0.15%, Fe 0.12%, Cu 1.65%, Mn 0.02%, Mg 2.40%, Cr 0.19%, Zn 5.71%, Ti 0.03%, Be 11ppm, Na 2ppm, with the balance being Al. The above chemical composition was maintained for subsequent melt purification, grain refinement, casting, and other processes, all under the same conditions as in Example 1.

[0245] Casting results: Due to the high Si and Fe content, with Si content exceeding Fe, the ingots developed cracks and were scrapped during the casting process.

[0246] Comparative Example 2

[0247] The process was carried out according to Example 1, except that the cooling water temperature was controlled at 19°C during the casting process.

[0248] Casting result: Due to excessively low cooling water temperature, the ingot developed cracks and was scrapped during the casting process.

[0249] Comparative Example 3

[0250] The process was carried out as described in Example 1, except that the casting speed was kept constant at 14 mm / min and the water flow rate was kept constant at 45 m³ / min during the casting process. 3 / h, the temperature at the end of the flow tray is kept constant at 700℃.

[0251] Casting result: Due to the rapid start-up speed and high temperature, the ingots developed cracks and were scrapped during the casting process.

[0252] Comparative Example 4

[0253] The process was carried out according to Example 1, except that the control conditions during the homogenization heat treatment were as follows: the ingot loading temperature was 80°C, the ingot heating rate was 5°C / h, the holding temperature was 440°C, and the holding time was 60h.

[0254] The results showed that the ingot structure still contained a lot of unbalanced crystallization formed during the casting process, resulting in poor heat homogenization.

[0255] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for preparing ultra-large 7A09 aluminum alloy round ingots, characterized in that, include: S1. Ingredients: The raw materials are proportioned according to the target alloy composition; in, The target alloy comprises, by weight percentage: Si: ≤0.10%; Fe: Si content +0.08% < Fe ≤ 0.30%; Cu: 1.20%~1.80%; Mn: ≤0.05%; Mg: 2.00%~3.00%; Cr：0.16%~0.30%； Zn: 5.10%~6.10%; Ti: ≤0.10%; The balance consists of Al and unavoidable impurities; The raw materials include: aluminum ingots, master alloys, pure metals, and primary waste. S2, Smelting and Composition Adjustment: The raw materials are melted, sampled, analyzed, and their composition is adjusted to obtain an alloy melt; S3, Melt purification: The alloy melt obtained in step S2 is refined in a furnace, then degassed and refined online, and then filtered to obtain a purified melt. S4. Grain refinement: Grain refinement was achieved using Al-5Ti-1B wire; S5, Casting: Pure aluminum is used to lay the bottom of the crystallizer, and then the aluminum liquid obtained in step S4 is introduced to fill the crystallizer, and then the casting is started. in, The purity of the aluminum is Al 99.70% or higher; The length of the casting is >1000mm; The casting conditions are as follows: ① Cooling water temperature: 22~28℃; ② Casting speed: When the casting length is < 600 mm, 10 mm / min ≤ casting speed ≤ 12 mm / min; when the casting length is 600 mm ≤ casting length < 1000 mm, 12 mm / min < casting speed ≤ 14 mm / min; when the casting length is ≥ 1000 mm, 14 mm / min < casting speed ≤ 17 mm / min. ③ Water flow rate: When the casting length is <100mm, the water flow rate is 50~70m³ / h. 3 / h; when the casting length is 100mm ≤ casting length < 500m, the water flow rate is 40~60m. 3 / h; when the casting length is 500mm ≤ casting length < 700m, the water flow rate is 30~50m³ / h. 3 / h; when the casting length is ≥700mm, the water flow rate is 20~30m³ / h. 3 / h; ④ Temperature at the end of the casting plate: When the casting length is <100mm, the temperature at the end of the casting plate is 675~690℃; when the casting length is 100mm≤300m, the temperature at the end of the casting plate is 680~690℃; when the casting length is 300mm≤500m, the temperature at the end of the casting plate is 685~700℃; when the casting length is ≥500mm, the temperature at the end of the casting plate is 690~705℃. S6. Soaking heat treatment: The ingot obtained in step S5 is subjected to homogenization heat treatment to obtain an ultra-large 7A09 aluminum alloy round ingot.

2. The preparation method according to claim 1, characterized in that, In step S5, the pure aluminum is molten aluminum formed from aluminum ingots with an Al grade of 99.70% or higher; The temperature of the bottom aluminum is 730~760℃, the filling time of the bottom aluminum is 150~250s, and the thickness of the bottom aluminum is ≥50mm; The filling time is 300~400s.

3. The preparation method according to claim 1, characterized in that, In step S5, a scraper is used during the casting process. The initial scraping length is ≥400mm, and the height of the scraper is 150~300mm.

4. The preparation method according to claim 1, characterized in that, In step S6, the conditions for the homogenization heat treatment are as follows: ingot loading temperature ≤150℃, ingot heating rate 10~30℃ / h, holding temperature 460~480℃, and holding time ≥50h.

5. The preparation method according to claim 1, characterized in that, In step S3, the alloy melt obtained in step S2 is refined in a furnace using a mixed gas of Ar + Cl2; wherein the volume percentage of Ar in the mixed gas is 94%~97%.

6. The preparation method according to claim 1, characterized in that, In step S3, the refining temperature in the furnace is 740~760℃, and the time is ≥30min.

7. The preparation method according to claim 1, characterized in that, In step S3, an online degassing and refining process is performed using a mixture of Ar and Cl2 gas; wherein the volume percentage of Ar in the mixture is 96% to 99%. The online degassing rotor speed for the online degassing refining process is 200~400 rpm; During the online degassing and refining process, the temperature of the online degassing chamber is 725~745℃.

8. The preparation method according to claim 1, characterized in that, In step S4, the amount of Al-5Ti-1B wire used is 1.5 to 2.5 kg / t.

9. The preparation method according to claim 1, characterized in that, In step S2, the melting temperature is 720~760℃; The composition adjustment includes: comparing the actual chemical composition analysis results before the furnace with the target value; if the element content is lower than the target value, adding intermediate alloys containing the element until the target value is reached; if the element content exceeds the target value, adding aluminum ingots into the furnace to reduce the excess element to the target value.

10. The preparation method according to claim 1, characterized in that, In step S3, the filter plate used for filtration has an accuracy of 50 ppi or higher; The temperature of the filter basin used in the filtration process is 715~730℃; The diameter of the 7A09 aluminum alloy extra-large round ingot is >1000mm.

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