An aluminum alloy ingot and a preparation method thereof

Abstract

The present invention provides a method for preparing an aluminum alloy ingot, which comprises the following steps carried out in sequence: batching, melting, composition adjustment, melt purification, melt filtration, grain refinement, casting, soaking and machining; by controlling the melt purification, melt filtration, grain refinement, casting and the composition of the alloy, the chemical composition, grain size and hydrogen content of the aluminum alloy ingot can be effectively controlled in this application.

Description

Technical Field

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

[0002] Al-Cu series aluminum alloys are widely used in the aerospace field due to their good process performance, easy welding and good high-temperature performance. With the increasing demand for the load-carrying capacity of spacecraft, larger-sized forgings are required to meet the product requirements. However, as the ingot size increases, it is more difficult to control the tissue uniformity (composition, grain size), forming and melt purity of the ingot, and uneven tissue will reduce the high-temperature performance and elongation of the aluminum alloy.

[0003] Furthermore, in order to meet the requirements of key structural components of a certain spacecraft, it is necessary to have application requirements such as high load-carrying capacity, high temperature performance, safety and reliability. For Al-Cu series alloys, the diameter of the ingot generally does not exceed 1000 mm, but in order to increase the load-carrying capacity, the diameter of the ingot needs to reach more than 1300 mm. However, for high-strength wrought aluminum alloys of the Al-Cu series, as the diameter increases and the performance requirements increase, the grain size, segregation degree and forming difficulty of the ingot increase geometrically, and the requirements for chemical composition and melt purity also increase significantly. Up to now, there is no mature production process for ingots with a diameter of more than 1300 mm. Summary of the Invention

[0004] The technical problem solved by the present invention is to provide a preparation method for an aluminum alloy ingot. The preparation method provided by the present application can stably control the chemical composition, grain size and hydrogen content of the aluminum alloy.

[0005] In view of this, the present application provides a preparation method for an aluminum alloy ingot, including the following steps carried out in sequence: batching, melting, composition adjustment, melt purification, melt filtration, grain refinement, casting, soaking and machining;

[0006] During the process of melt purification, a mixed gas of argon and chlorine is used for rotary degassing, the refining time is ≥30 min, and the online degassing rotor speed is 200 - 300 rpm;

[0007] During the process of melt filtration, a ceramic filter plate with ≥40 + 40 ppi is used for filtration;

[0008] During the process of grain refinement, the grain refiner used is Al-5Ti-1B, and the dosage is 3 - 10 kg / t;

[0009] During the process of casting, the casting speed is 10 - 18 mm / min, the cooling water flow rate is 20 - 50 m 3 / h, and the temperature at the end of the runner is 690 - 720 °C;

[0010] The composition of the aluminum alloy ingot is as follows: Si ≤ 0.05 wt%, Fe ≤ 0.05 wt%, Cu 5.8 - 6.4 wt%, Mn 0.2 - 0.4 wt%, Mg < 0.02 wt%, Cr < 0.05 wt%, Zn < 0.10 wt%, Ti 0.02 - 0.06 wt%, Zr 0.10 - 0.15 wt%, V 0.06 - 0.12 wt%, Pb < 0.002 wt%, Bi < 0.002 wt%, Sn < 0.002 wt%, and the balance is Al.

[0011] Preferably, during the melting process, a combined treatment method of mechanical stirring and electromagnetic stirring is adopted.

[0012] Preferably, during the melt purification process, the hydrogen content after in-furnace purification ≤ 0.27 ml / 100 g Al, and the hydrogen content after online degassing ≤ 0.10 ml / 100 g Al.

[0013] Preferably, during the grain refinement process, the residence time of the grain refiner in the melt does not exceed 25 min, and the melt temperature at the addition position of the grain refiner is 715 - 750 °C.

[0014] Preferably, during the casting process, pure aluminum with a grade of Al99.70 is used for bottom laying, the temperature of the bottom-laying aluminum melt is 730 - 780 °C, and the thickness of the bottom-laying aluminum is 50 - 80 mm.

[0015] Preferably, the temperature of the refining is 740 - 760 °C, and the time is 30 - 40 min.

[0016] Preferably, the casting speed is 11 - 17 mm / min, the cooling water flow rate is 25 - 50 m 3 / h, and the temperature at the end of the launder is 690 - 710 °C.

[0017] Preferably, the specification of the aluminum alloy ingot is Ф1300 - Ф1400 mm.

[0018] This application also provides an aluminum alloy ingot, including: Si ≤ 0.05 wt%, Fe ≤ 0.05 wt%, Cu 5.8 - 6.4 wt%, Mn 0.2 - 0.4 wt%, Mg < 0.02 wt%, Cr < 0.05 wt%, Zn < 0.10 wt%, Ti 0.02 - 0.06 wt%, Zr 0.10 - 0.15 wt%, V 0.06 - 0.12 wt%, Pb < 0.002 wt%, Bi < 0.002 wt%, Sn < 0.002 wt%, and the balance is Al.

[0019] The present application provides a method for preparing an aluminum alloy ingot, which includes the following steps carried out in sequence: batching, melting, composition adjustment, melt purification, melt filtration, grain refinement, casting, homogenization, and machining; by controlling the melt purification, melt filtration, grain refinement, casting, and the composition of the alloy, the chemical composition, grain size, and hydrogen content of the aluminum alloy ingot can be effectively controlled. Detailed Embodiments

[0020] To further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0021] In view of the requirements for the performance of aluminum alloy ingots with a diameter of more than 1300 mm in the prior art, the present application provides a method for preparing a large-grain-size aluminum alloy ingot. By adjusting the alloy composition and related processes in the preparation process, the chemical composition and grain size of the aluminum alloy are stably controlled, and the hydrogen content is ≤0.10 ml / 100 g Al, meeting the quality requirements of new space vehicles. Specifically, an embodiment of the present invention discloses a method for preparing an aluminum alloy ingot, which includes the following steps carried out in sequence: batching, melting, composition adjustment, melt purification, melt filtration, grain refinement, casting, homogenization, and machining;

[0022] During the melt purification process, a mixed gas of argon and chlorine is used for rotary degassing, the refining time is ≥30 min, and the online degassing rotor speed is 200 - 300 rpm;

[0023] During the melt filtration process, a ceramic filter plate with ≥40 + 40 ppi is used for filtration;

[0024] During the grain refinement process, the grain refiner used is Al-5Ti-1B, and the dosage is 3 - 10 kg / t;

[0025] During the casting process, the casting speed is 10 - 18 mm / min, the cooling water flow rate is 20 - 50 m 3 / h, and the temperature at the end of the launder is 690 - 720 °C;

[0026] The composition of the aluminum alloy ingot is: Si ≤ 0.05 wt%, Fe ≤ 0.05 wt%, Cu 5.8 - 6.4 wt%, Mn 0.2 - 0.4 wt%, Mg < 0.02 wt%, Cr < 0.05 wt%, Zn < 0.10 wt%, Ti 0.02 - 0.06 wt%, Zr 0.10 - 0.15 wt%, V 0.06 - 0.12 wt%, Pb < 0.002 wt%, Bi < 0.002 wt%, Sn < 0.002 wt%, and the balance is Al.

[0027] In the process of preparing aluminum alloy ingots, the preparation steps include batching, melting, composition adjustment, melt purification, melt filtration, grain refinement, casting, soaking, and machining, which are carried out in sequence.

[0028] In the above preparation steps, batching is required first. In order to meet the high low-temperature mechanical properties, fracture toughness, and welding properties of aluminum alloy ingots, this application preferably uses high-purity aluminum ingots and other raw materials with better uniformity, ensuring that elements such as Si, Fe, and other impurity elements such as Pb, Bi, and Sn are controlled at a low level; the raw materials use aluminum ingots with a grade of Al99.99 and above, the Mn element is added in the form of an additive, and the others are added in the form of master alloys, and no waste materials are used.

[0029] According to the present invention, melting is carried out after batching. Since alloy elements with a relatively large density (such as Cu) are prone to sink to the bottom, and the addition of alloy elements cannot be absolutely uniform, this results in non-uniform distribution of alloy elements between the upper and lower layers of the melt and between different regions in the furnace; if the stirring is not thorough (without sufficient time and eliminating dead corners), it is easy to cause non-uniform melt chemical composition. In order to make the composition more uniform, the melt in the furnace is treated by a combined method of mechanical stirring and electromagnetic stirring.

[0030] This application conducts melt purification after melting. It is a process of removing gases, inclusions, and harmful elements in the aluminum alloy melt by using physical and chemical principles and corresponding process measures, including in-furnace purification, on-line degassing, and filtration, etc. For in-furnace purification, that is, introducing gas into the melt to remove harmful gases and impurities. The present invention preferably adopts the method of rotary degassing with a mixed gas of argon and chlorine; argon does not react with the melt, and chlorine is a reactive gas. Although chlorine refining has good effects, it is harmful to the environment and equipment. Therefore, a reasonable ratio of the argon-chlorine mixed gas is used to improve the refining effect and reduce its harmful effects; the refining temperature is 740 - 760 °C, and the refining time ≥ 30 min. More specifically, the refining time is 30 - 40 min; it can ensure that the hydrogen content after in-furnace purification ≤ 0.27 ml / 100 g Al. For on-line degassing, the gas forms dispersed and fine bubbles through a high-speed rotating nozzle, and at the same time agitates the melt to make the bubbles evenly dispersed throughout the melt, thereby producing the melt purification effect of degassing and slag removal; the present invention adopts a series connection method of 2 degassing devices, and the medium is a mixed gas of argon and chlorine; the rotational speed of the on-line degassing rotor is 200 - 300 rpm, and the argon flow rate is 3 - 5 Nm 3 / h, which can ensure that the hydrogen content after in-furnace purification ≤ 0.10 ml / 100 g Al. For on-line filtration, it is the most effective and reliable means to remove non-metallic inclusions in the aluminum melt; the present invention adopts a foam ceramic filter plate with 40 + 40 ppi and above to filter, reducing the inclusions to the lowest level.

[0031] According to the present invention, a grain refinement process is carried out. The present invention selects Al-5Ti-1B wire as the grain refiner, and the dosage is 3-10 kg / t, more specifically 4.5-6 kg / t. The residence time of the grain refiner in the melt does not exceed 25 min, and the melt temperature at the position where the grain refiner is added is controlled at 715-750 °C.

[0032] After this application, the casting process is entered. In order to ensure the formation of the ingot, pure aluminum is used for bottom laying during casting. The grade of the aluminum ingot for bottom laying is Al99.70, the temperature of the molten aluminum for bottom laying is 730-780 °C, and the thickness of the bottom-laying aluminum is 50-80 mm; in a specific embodiment, the temperature of the molten aluminum for bottom laying is 730-760 °C, and the thickness of the bottom-laying aluminum is 60-70 mm. Any treatment that can promote nucleation and inhibit grain growth can refine grains; in order to obtain a fine-grained structure, the present invention mainly adopts the method of increasing the degree of supercooling during the casting process, that is, reducing the casting speed, increasing the cooling speed of the liquid metal, and lowering the pouring temperature; if the pouring temperature is too low, defects such as inclusions and shiny crystals are likely to appear; if the casting speed is too low, the compactness of the ingot becomes poor, and defects such as porosity, oxide film, and cold shut are likely to appear; increasing the cooling speed can also refine the size of the primary crystal compounds and reduce the degree of regional segregation. The present invention selects the temperature at the end of the runner plate to be 690-710 °C, the casting speed to be 11-17 mm / min, and the cooling water flow rate to be 25-50 m 3 / h.

[0033] The preparation method of the aluminum alloy ingot provided by this application is applicable to aluminum alloys with a diameter of Ф1300-1400 mm, and is particularly applicable to aluminum alloys with a diameter of Ф1350 mm.

[0034] This application provides an aluminum alloy ingot, including: Si≤0.05 wt%, Fe≤0.05 wt%, Cu 5.8-6.4 wt%, Mn 0.2-0.4 wt%, Mg <0.02 wt%, Cr <0.05 wt%, Zn <0.10 wt%, Ti 0.02-0.06 wt%, Zr 0.10-0.15 wt%, V 0.06-0.12 wt%, Pb <0.002 wt%, Bi <0.002 wt%, Sn <0.002 wt%, and the balance is Al.

[0035] In the composition of the above aluminum alloy ingot, Si and Fe are impurity elements. Reducing their content can reduce the insoluble second phase in the ingot and improve the uniformity and plasticity of the ingot; Pb, Bi, and Sn are impurity elements and all are low-melting-point alloying elements, which affect the welding performance of the product, and their content needs to be strictly controlled. Specifically, the content of Pb is <0.0015 wt%, the content of Bi is <0.0015 wt%, and the content of Sn is <0.0015 wt%; The Cu element exists in the form of CuAl2 phase, which mainly plays a strengthening role. However, as the content of the Cu element increases, the strength increases but the elongation decreases, and too much Cu will also cause poor corrosion resistance. Specifically, the content of Cu is 5.9 - 6.3 wt%; Zr is a commonly added element in aluminum alloys. Zr and Al form ZrAl3 compounds, which can hinder the recrystallization process and refine the recrystallized grains; but when Zr is present, part of Ti in TiAl3 and TiB2 is replaced by Zr, forming aluminides (TiX, ZrX)Al3 and borides (TiX, ZrX)B2, which change the lattice constant, the nucleation effect disappears, and TiB2 is poisoned and loses its refining effect, reducing the grain refinement effect of titanium and boron, resulting in coarse grains. Specifically, the content of Zr is 0.10 - 0.13 wt%; V forms refractory compounds in aluminum alloys, which plays a role in refining grains during the melting and casting process. At the same time, V also has the effect of refining the recrystallized structure and raising the recrystallization temperature. However, VAl3 aggregates and grows with TiAl3 and TiB2 particles, causing TiB2 to be poisoned and lose its refining effect, leading to refinement decline. Specifically, the content of V is 0.08 - 0.12 wt%. The content of Mn is 0.25 - 0.35 wt%, and the content of Ti is 0.03 - 0.06 wt%.

[0036] To further understand the present invention, the following examples are used to illustrate in detail the aluminum alloy ingot and its preparation method provided by the present invention. The protection scope of the present invention is not limited by the following examples.

[0037] Example 1

[0038] Prepare the aluminum alloy according to the following method: successively carry out batching, melting, composition adjustment, melt purification, melt filtration, grain refinement, casting, homogenization, sawing, and detection;

[0039] Ingot specification: Ф1350mm;

[0040] Batching process: Carry out batching according to the alloy composition and technical requirements, and use Al99.99 aluminum ingots, Mn agents, and master alloys for batching;

[0041] Smelting process: After melting the alloy raw materials completely, samples are taken for analysis; the melting temperature in the furnace is 720 - 760 °C, and electromagnetic stirring and mechanical stirring are used to treat the melt. Mechanical stirring is carried out 3 times, 5 minutes each time, and electromagnetic stirring is carried out 4 times, 30 minutes each time;

[0042] Composition adjustment: Compare the actual analysis results of the chemical composition in front of the furnace with the pre - obtained target values. If the element content is lower than the target value, add intermediate alloys containing certain elements until the target value is reached. If the element content exceeds the target value, add aluminum ingots into the furnace to reduce the excessive elements to the target value;

[0043] Melt purification: In the furnace, the mixture of Ar + Cl2 gas is used for refining for 30 minutes; the liquid hydrogen content of the refined melt is 0.25 ml / 100 g Al;

[0044] On - line purification: On - line, the mixture of Ar + Cl2 gas is used for refining. Adopt the series connection mode of 2 degassing devices, and the medium for degassing is the argon - chlorine mixed gas. The melt is pretreated 15 minutes before casting; the liquid hydrogen content of the melt after on - line purification is 0.087 ml / 100 g Al;

[0045] On - line filtration: Filtration is carried out using 50 + 50 ppi foam ceramic filter plates;

[0046] On - line grain refinement: Add Al - 5Ti - 1B wire during on - line grain refinement, and the dosage is 5 kg / t;

[0047] Casting parameters: The temperature of the molten aluminum at the end of the runner is 702 °C; the casting speed is 12 mm / min; the cooling water flow rate is 30 m 3 / h; the cooling water temperature is 26 °C;

[0048] Sawing process: Cut 400 mm at the gate part and 500 mm at the bottom.

[0049] Testing process:

[0050] Macro - structure results of the ingot: The grain size is 3.5 levels and the porosity is 1 level; the testing method is GB / T3246.2 "Test Methods for Microstructure of Wrought Aluminum and Aluminum Alloy Products - Part 2 Macro - structure Test Methods";

[0051] Chemical composition: Si 0.03%, Fe 0.04%, Cu 6.12%, Mn 0.28%, Mg 0.01%, Cr 0.01%, Zn 0.01%, Ti 0.05%, Zr 0.13%, V 0.10%, Pb 0.0008%, Bi 0.0005%, Sn 0.0007%; the testing methods are GB / T 20975 "Analytical Methods for Aluminum Alloys" and GB / T "17432 Photometric Direct - Reading Emission Spectrometric Analysis Method for Aluminum and Aluminum Alloys";

[0052] Liquid hydrogen content: 0.087 ml / 100 g Al; The detection method is "YS / T 600 Method for Measuring Hydrogen in Liquid Aluminum and Aluminum Alloys - Closed Circuit Circulation Method".

[0053] Example 2

[0054] Prepare the aluminum alloy according to the following method: successively carry out batching, melting, composition adjustment, melt purification, melt filtration, grain refinement, casting, soaking, sawing, and detection;

[0055] Ingot specification: Ф1350 mm;

[0056] Batching process: Carry out batching according to the alloy composition and technical requirements, and use Al99.99 aluminum ingots, Mn agents, and master alloys for batching;

[0057] Melting process: After melting the alloy raw materials, take samples for analysis; The melting temperature in the furnace is 720 - 760 °C, and the melt is treated by electromagnetic stirring and mechanical stirring. Mechanical stirring is carried out 3 times, 5 minutes each time, and electromagnetic stirring is carried out 4 times, 30 minutes each time;

[0058] Composition adjustment: Compare the actual analysis results of the chemical composition in the furnace with the pre - obtained target values. If the element content is lower than the target value, add a certain master 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 excessive elements to the target value;

[0059] Melt purification: Refine the furnace with a mixed gas of Ar + Cl2 for 40 minutes; The liquid hydrogen content of the melt after refining is 0.23 ml / 100 g Al;

[0060] On - line purification: Refine on - line with a mixed gas of Ar + Cl2. Adopt a series connection method of 2 degassing devices, and the medium is argon - chlorine mixed gas for degassing. Pretreat the melt 15 minutes before casting; The liquid hydrogen content of the melt after on - line purification is 0.081 ml / 100 g Al;

[0061] On - line filtration: Filter with 50 + 50 ppi foam ceramic filter plates;

[0062] On - line refinement: Add Al - 5Ti - 1B wire for on - line grain refinement, with a dosage of 5 kg / t;

[0063] Casting parameters: The temperature of the molten aluminum at the end of the launder is 700 °C; The casting speed is 13 mm / min; The cooling water flow rate is 35 m 3 / h; The cooling water temperature is 27 °C;

[0064] Sawing process: Cut 400 mm at the sprue part and 500 mm at the bottom.

[0065] Detection process:

[0066] Macrostructure results of the ingot: Grain size is grade 3, and porosity is grade 1; The testing method is GB / T 3246.2 "Test Methods for Microstructure of Wrought Aluminum and Aluminum Alloy Products - Part 2 Macrostructure Test Methods".

[0067] Chemical composition: Si 0.03%, Fe 0.04%, Cu 6.05%, Mn 0.26%, Mg 0.01%, Cr 0.01%, Zn 0.01%, Ti 0.05%, Zr 0.12%, V 0.08%, Pb 0.0010%, Bi 0.0006%, Sn 0.0008%; The testing methods are GB / T 20975 "Analytical Methods for Aluminum Alloys" and GB / T "17432 Optical Emission Spectrometric Analysis Method for Aluminum and Aluminum Alloys".

[0068] Liquid hydrogen content: 0.081 ml / 100 g Al; The testing method is "YS / T 600 Test Method for Measuring Hydrogen in Liquid Aluminum and Aluminum Alloys - Closed-loop Circulation Method".

[0069] Example 3

[0070] Prepare the aluminum alloy according to the following method: Conduct batching, melting, composition adjustment, melt purification, melt filtration, grain refinement, casting, homogenization, sawing, and testing in sequence;

[0071] Ingot specification: Ф1350 mm;

[0072] Batching process: Conduct batching according to the alloy composition and technical requirements, and use Al99.99 aluminum ingots, Mn agents, and master alloys for batching;

[0073] Melting process: Take samples for analysis after melting all the alloy raw materials; The melting temperature in the furnace is 720 - 760 °C. Use electromagnetic stirring and mechanical stirring to process the melt. Mechanical stirring is carried out 3 times, 5 minutes each time, and electromagnetic stirring is carried out 4 times, 30 minutes each time;

[0074] Composition adjustment: Compare the actual analysis results of the chemical composition in front of the furnace with the pre-obtained target values. If the element content is lower than the target value, add a certain master 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 over-standard element to the target value;

[0075] Melt purification: Refine the melt in the furnace with a mixed gas of Ar + Cl2 for 40 minutes; The liquid hydrogen content of the refined melt is 0.24 ml / 100 g Al;

[0076] Online purification: During online operation, refining is carried out using a mixed gas of Ar + Cl2. Two degassing devices are connected in series, and the medium for degassing is the argon-chlorine mixed gas. The melt is pretreated 15 minutes before casting. The liquid hydrogen content of the melt after online purification is 0.083 ml / 100 g Al;

[0077] Online filtration: Filtration is carried out using 50 + 50 ppi foam ceramic filter plates;

[0078] Online grain refinement: Al-5Ti-1B wire is added for online grain refinement, with a dosage of 5 kg / t;

[0079] Casting parameters: The temperature of the molten aluminum at the end of the runner is 703 °C; the casting speed is 13 mm / min; the cooling water flow rate is 35 m 3 / h; the cooling water temperature is 25 °C;

[0080] Sawing process: Cut 400 mm at the gate part and 500 mm at the bottom.

[0081] Inspection process:

[0082] Macrostructure results of the ingot: Grain size is grade 3, and porosity is grade 1; The inspection method is GB / T 3246.2 "Test Methods for Microstructure of Wrought Aluminum and Aluminum Alloy Products - Part 2 Macrostructure Inspection Methods";

[0083] Chemical composition: Si 0.02%, Fe 0.04%, Cu 6.01%, Mn 0.25%, Mg 0.01%, Cr 0.01%, Zn 0.01%, Ti 0.05%, Zr 0.12%, V 0.09%, Pb 0.0010%, Bi 0.0010%, Sn 0.0010%; The inspection methods are GB / T 20975 "Analysis Methods for Aluminum Alloys" and GB / T "17432 Optical Emission Spectrometric Analysis Methods for Aluminum and Aluminum Alloys";

[0084] Liquid hydrogen content: 0.083 ml / 100 g Al; The inspection method is "YS / T 600 Test Method for Measuring Hydrogen in Liquid Aluminum and Aluminum Alloys - Closed Circuit Circulation Method".

[0085] Comparative Example 1

[0086] The aluminum alloy is prepared according to the following method: Charging, melting, composition adjustment, melt purification, melt filtration, grain refinement, casting, homogenization, sawing, and inspection are carried out in sequence;

[0087] Ingot specification: Ф1350 mm;

[0088] Charging process: Charging is carried out according to the alloy composition and technical requirements, using Al99.99 aluminum ingots, Mn agents, and master alloys for charging;

[0089] Smelting process: After melting the alloy raw materials completely, samples are taken for analysis; the melting temperature in the furnace is 720 - 760 °C, and the melt is treated by electromagnetic stirring and mechanical stirring. Mechanical stirring is carried out 3 times, 5 minutes each time, and electromagnetic stirring is carried out 4 times, 30 minutes each time;

[0090] Composition adjustment: Compare the actual analysis results of the chemical composition in front of the furnace with the pre - obtained target values. If the element content is lower than the target value, intermediate alloys containing certain elements are added until the target value is reached. If the element content exceeds the target value, aluminum ingots are added into the furnace to reduce the excessive elements to the target value;

[0091] Melt purification: The furnace is refined with a mixed gas of Ar + Cl2 for 30 minutes; the liquid hydrogen content of the refined melt is 0.26 ml / 100 g Al;

[0092] On - line purification: On - line, a mixed gas of Ar + Cl2 is used for refining, single - stage degassing is adopted, and the melt is pretreated 15 minutes before casting; the liquid hydrogen content of the melt after on - line purification is 0.105 ml / 100 g Al;

[0093] On - line filtration: Filtration is carried out using a 50 + 50 ppi foam ceramic filter plate;

[0094] On - line grain refinement: Al - 5Ti - 1B wire is added for on - line grain refinement, and the dosage is 3.5 kg / t;

[0095] Casting parameters: The temperature of the molten aluminum at the end of the runner is 700 °C; the casting speed is 13 mm / min; the cooling water flow rate is 35 m 3 / h; the cooling water temperature is 28 °C;

[0096] Sawing process: Cut 400 mm at the gate part and 500 mm at the bottom.

[0097] Testing process:

[0098] Macro - structure results of the ingot: The grain size is 4.5 grades, the grains are relatively large, and the porosity is grade 1; the testing method is GB / T3246.2 "Test Methods for Microstructure of Wrought Aluminum and Aluminum Alloy Products - Part 2 Macro - structure Test Methods";

[0099] Chemical composition: Si 0.03%, Fe 0.05%, Cu 6.14%, Mn 0.28%, Mg 0.01%, Cr 0.01%, Zn 0.01%, Ti 0.05%, Zr 0.13%, V 0.11%, Pb 0.0009%, Bi 0.0005%, Sn 0.0006%; the testing methods are GB / T 20975 "Analysis Methods for Aluminum Alloys" and GB / T "17432 Optical Emission Spectrometric Analysis Methods for Aluminum and Aluminum Alloys";

[0100] Liquid hydrogen content: 0.105 ml / 100 g Al, with a relatively high hydrogen content; the detection method is "YS / T 600 Method for Measuring Hydrogen in Liquid Aluminum and Aluminum Alloys - Closed Circuit Circulation Method".

[0101] The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0102] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an aluminum alloy ingot, comprising the following steps carried out in sequence: batching, melting, composition adjustment, melt purification, melt filtration, grain refinement, casting, homogenization, and machining; characterized in that, During the melting process, a combined treatment method of mechanical stirring and electromagnetic stirring is adopted; During the melt purification process, a rotary degassing method using a mixed gas of argon and chlorine is adopted, the refining time is ≥30 min, and the on-line degassing rotor speed is 200 - 300 rpm; during the melt purification process, the hydrogen content after in-furnace purification is ≤0.27 ml / 100 g Al, and the hydrogen content after on-line degassing is ≤0.10 ml / 100 g Al; During the melt filtration process, a ceramic filter plate with ≥40 + 40 ppi is used for filtration; During the grain refinement process, the grain refiner used is Al-5Ti-1B, and the dosage is 3 - 10 kg / t; the residence time after the grain refiner is added to the melt does not exceed 25 min, and the melt temperature at the position where the grain refiner is added is 715 - 750 °C; During the casting process, the casting speed is 10 - 18 mm / min, the cooling water flow rate is 20 - 50 m 3 / h, and the temperature at the end of the runner is 690 - 720 °C; the bottom of the mold is paved with pure aluminum melt with a grade of Al99.70, the temperature of the bottom-paving aluminum melt is 730 - 780 °C, and the thickness of the bottom-paving aluminum melt is 50 - 80 mm; The composition of the aluminum alloy ingot is: Si ≤ 0.05 wt%, Fe ≤ 0.05 wt%, Cu 5.8 - 6.4 wt%, Mn 0.2 - 0.4 wt%, Mg < 0.02 wt%, Cr < 0.05 wt%, Zn < 0.10 wt%, Ti 0.02 - 0.06 wt%, Zr 0.10 - 0.15 wt%, V 0.06 - 0.12 wt%, Pb < 0.002 wt%, Bi < 0.002 wt%, Sn < 0.002 wt%, and the balance is Al; The specification of the aluminum alloy ingot is Ф1350 - Ф1400 mm.

2. The preparation method according to claim 1, characterized in that, The refining temperature is 740 - 760 °C, and the time is 30 - 40 min.

3. The preparation method according to claim 1, characterized in that, The casting speed is 11 - 17 mm / min, the cooling water flow rate is 25 - 50 m 3 / h, and the temperature at the end of the runner plate is 690 - 710 °C.

4. An aluminum alloy ingot, with the composition: Si ≤ 0.05 wt%, Fe ≤ 0.05 wt%, Cu 5.8 - 6.4 wt%, Mn 0.2 - 0.4 wt%, Mg < 0.02 wt%, Cr < 0.05 wt%, Zn < 0.10 wt%, Ti 0.02 - 0.06 wt%, Zr 0.10 - 0.15 wt%, V 0.06 - 0.12 wt%, Pb < 0.002 wt%, Bi < 0.002 wt%, Sn < 0.002 wt%, and the balance is Al; the preparation method of the aluminum alloy ingot is the preparation method described in any one of claims 1 - 3.