Large-flow aluminum alloy continuous casting ultrasonic online melt treatment method

Abstract

The invention belongs to the technical field of aluminum alloy continuous casting, and particularly relates to a large-flow aluminum alloy continuous casting ultrasonic online melt treatment method. The treatment method comprises the steps that (1) molten aluminum or alloy molten aluminum continuously flows into a continuous casting machine through a runner, and a tundish is arranged on the runner; (2) the molten aluminum or alloy molten aluminum is subjected to ultrasonic pretreatment; (3) after pretreatment, flowing into a continuous casting machine through a small casting ladle; (4) on-line grain refinement treatment is carried out; and (5) casting into a casting blank by adopting a continuous casting process. The problems that in the existing large-flow aluminum alloy continuous casting process, the grain refinement effect is poor, the purity degree is insufficient, and the component uniformity is poor are solved, micron-level grain refinement is achieved, the average grain size reaches 45 micrometers or below, and the grain size grade reaches 5.5 or above.

Description

Technical Field

[0001] This invention belongs to the field of continuous aluminum alloy casting technology, specifically relating to a method for ultrasonic online melt treatment in continuous aluminum alloy casting with high flow rate. Background Technology

[0002] Aluminum alloys are widely used in aerospace, automobile manufacturing and other fields due to their excellent properties. Their physical and chemical properties are closely related to grain size, compositional uniformity, hydrogen content and purity.

[0003] The finer the grains, the more uniform the composition, the higher the purity, and the lower the hydrogen content of aluminum alloys, the better their performance is generally.

[0004] Traditional methods for refining the grains of aluminum alloys often involve adding grain refiners. However, this method suffers from drawbacks, including difficulty in precisely controlling the dosage, the refiner's susceptibility to factors such as addition time and temperature leading to potential failure, and unsatisfactory refining effects for high-volume continuous casting of aluminum alloys, failing to meet the production requirements of high-quality aluminum alloy products. Furthermore, the addition of grain refiners can affect the purity of the aluminum alloy, causing an increase in resistivity. These refiners exist in the form of hard particles, leading to a decline in the quality of subsequent processed products and even scrapping them.

[0005] Existing technologies include those that use ultrasound to refine grains, such as CN201510291549, but these only achieve millimeter-level grain refinement. Summary of the Invention

[0006] This invention aims to solve the problems of poor grain refinement, insufficient purity, and poor compositional uniformity in existing high-flow-rate continuous aluminum alloy casting processes. It provides an ultrasonic online melt treatment technology that can effectively refine grains, improve the purity and compositional uniformity of aluminum alloys, and is suitable for high-flow-rate continuous casting production. This technology achieves micron-level grain refinement, including reducing the average grain size to below 45 μm and the grain size grade to above 5.5.

[0007] Therefore, the present invention provides a method for ultrasonic online melt treatment of high-flow-rate aluminum alloy continuous casting, the method comprising:

[0008] 1) Molten aluminum or molten alloy aluminum flows continuously into the continuous casting machine through the flow channel, and an intermediate ladle is set on the flow channel;

[0009] 2) An ultrasonic pretreatment device is installed on the tundish to perform ultrasonic pretreatment on the molten aluminum or alloy aluminum liquid to eliminate gases and impurities in the molten metal and promote the initial formation of crystal nuclei.

[0010] 3) Pretreated molten aluminum or alloy molten aluminum flows into the continuous casting machine through a small ladle;

[0011] 4) The ultrasonic probe is inserted into the sprue at an angle of 40-55 degrees, with an insertion depth of 50-90mm; the output frequency of the ultrasonic generator is 19.8-22kHz and the power is 300-500W, to perform online grain refinement treatment on molten aluminum or alloy aluminum liquid.

[0012] 5) The billet is cast using a continuous casting process. The solidified billet is then continuously rolled into finished products of different specifications or sheared into alloy ingots.

[0013] In step 4), the angle at which the ultrasonic probe is inserted into the nozzle at an angle of 40-55 degrees refers to the angle between the ultrasonic probe and the horizontal plane being 40-55 degrees.

[0014] As a preferred embodiment, in step 2) of the above-mentioned high-flow-rate aluminum alloy continuous casting ultrasonic online melt treatment method:

[0015] The frequency of ultrasonic pretreatment is 18-22kHz;

[0016] The power of ultrasonic pretreatment is 400-1000W;

[0017] The insertion depth of the probe of the ultrasonic pretreatment device is 80-150mm.

[0018] As a further preferred option, in the ultrasonic pretreatment:

[0019] For pure aluminum molten metal: the frequency of ultrasonic pretreatment is 20.3-21.4kHz, the power is 780-820W; the insertion depth of the probe of the ultrasonic pretreatment device is 140-150mm.

[0020] For molten aluminum-silicon alloy: the frequency of ultrasonic pretreatment is 18.7-19.6kHz, the power is 680-720W; the insertion depth of the probe of the ultrasonic pretreatment device is 120-140mm.

[0021] For aluminum-silicon-magnesium alloy liquid: the frequency of ultrasonic pretreatment is 19.2-20.5kHz, the power is 580-620W; the insertion depth of the probe of the ultrasonic pretreatment device is 90-110mm.

[0022] For aluminum-magnesium alloy liquid: the frequency of ultrasonic pretreatment is 19.9-20.7kHz, the power is 950-1000W; the insertion depth of the probe of the ultrasonic pretreatment device is 130-150mm.

[0023] For aluminum-silicon-copper alloy liquid: the frequency of ultrasonic pretreatment is 18.6-19.9kHz, and the power is 880-920W; the insertion depth of the probe of the ultrasonic pretreatment device is 80-100mm.

[0024] As a preferred embodiment, in step 4) of the above-mentioned high-flow-rate aluminum alloy continuous casting ultrasonic online melt treatment method:

[0025] For pure aluminum molten metal: the ultrasonic probe is inserted into the sprue at an angle of 43-45 degrees to a depth of 80-90mm; the output frequency of the ultrasonic generator is 19.8-20.2kHz and the power is 480-500W, and the grain size of the solidified billet can reach level 5.6.

[0026] For aluminum-silicon alloy melt: the ultrasonic probe is inserted into the sprue at an angle of 46-48 degrees, with an insertion depth of 70-90mm; the output frequency of the ultrasonic generator is 20.8-21.6kHz, and the power is 300-320W; the grain size of the solidified billet can reach grade 6.2.

[0027] For aluminum-silicon-magnesium alloy liquid: the ultrasonic probe is inserted into the sprue at an angle of 51-53 degrees, with an insertion depth of 60-80mm; the output frequency of the ultrasonic generator is 21.6-22kHz, and the power is 380-420W, so that the grain size of the solidified billet can reach grade 7.6.

[0028] For aluminum-magnesium alloy liquid: the ultrasonic probe is inserted into the sprue at an angle of 50-52 degrees, with an insertion depth of 70-90mm; the output frequency of the ultrasonic generator is 20.8-21.7kHz, and the power is 380-420W; the grain size of the solidified billet can reach grade 7.1.

[0029] For aluminum-silicon-copper alloy liquid: the ultrasonic probe is inserted into the sprue at an angle of 45-47 degrees, with an insertion depth of 80-90mm; the output frequency of the ultrasonic generator is 20.4-21.6kHz, and the power is 480-500W, so that the grain size of the solidified billet can reach grade 6.3.

[0030] As a preferred embodiment, in the above-mentioned ultrasonic online melt treatment method for continuous casting of aluminum alloys with high flow rate, the relationship between the temperature T2 of the molten aluminum or alloy aluminum liquid in the tundish and its liquidus temperature T1 is T2 = T1 + (40~60)℃. Further preferably:

[0031] For pure aluminum melt: T2 = T1 + (47~49)℃;

[0032] For aluminum-silicon alloy melt: T2 = T1 + (52~54)℃;

[0033] For aluminum-silicon-magnesium alloy melt: T2 = T1 + (56~58)℃;

[0034] For aluminum-magnesium alloy melt: T2 = T1 + (54~56)℃;

[0035] For aluminum-silicon-copper alloy liquid: T2 = T1 + (58~60)℃.

[0036] As a preferred embodiment, in step 1) of the above-mentioned ultrasonic online melt treatment method for continuous casting of high-flow-rate aluminum alloys, an intermediate ladle is set on the flow channel at a distance of 1000-1200mm from the sprue.

[0037] As a preferred embodiment, in step 2) of the above-mentioned high-flow-rate aluminum alloy continuous casting ultrasonic online melt treatment method, 2-3 sets of ultrasonic pretreatment devices are installed on the tundish.

[0038] As a preferred embodiment, in step 3) of the above-mentioned high-flow-rate aluminum alloy continuous casting ultrasonic online melt treatment method, the pretreated aluminum liquid or alloy aluminum liquid flows into the continuous casting machine through a small ladle at a rate of 6-8 tons per hour.

[0039] As a preferred embodiment, the tundish size and capacity of the above-mentioned high-flow-rate aluminum alloy continuous casting ultrasonic online melt treatment method meet at least one of the following characteristics:

[0040] The capacity of the intermediate batch is 295-383 kg;

[0041] The length of the intermediate bag is 1300-1400mm, the width is 280-320mm, and the depth is 270-350mm;

[0042] The height and volume of molten aluminum within it satisfy at least one of the following characteristics:

[0043] The liquid level of molten aluminum or alloy aluminum in the tundish is 192-300 mm.

[0044] The volume of molten aluminum or alloy aluminum in the tundish is 210-328 kg.

[0045] To achieve better grain refinement.

[0046] As a preferred embodiment, step 5) of the above-mentioned ultrasonic online melt treatment method for continuous casting of high-flow-rate aluminum alloys satisfies the following characteristics:

[0047] Cast using continuous casting process to produce cross-sectional areas of 3200-3600 mm² 2 Trapezoidal casting billet;

[0048] The casting speed is 6.0-8.0 t / h;

[0049] The cooling water pressure is 0.3-0.6 MPa, and the cooling water temperature is 25-33℃.

[0050] According to the present invention, the grain size of the solidified billet prepared by the above method is 5-8.

[0051] According to the present invention, the average grain size of the solidified cast billet prepared by the above method is ≤45μm.

[0052] Compared with the prior art, the present invention has at least the following beneficial effects:

[0053] 1. It improves the uniformity of alloy composition, resulting in a more uniform internal structure.

[0054] 2. It reduces the hydrogen content in the alloy melt, improves the purity of the alloy, and obtains a billet with excellent physical and chemical properties.

[0055] 3. The grain size of the cast billet has been significantly improved, achieving micron-level grain refinement with an average grain size below 45μm and a grain size grade of 5.5 or higher.

[0056] 4. Improved the conductivity of the product.

[0057] 5. The adoption of this technology has greatly improved the quality of large-flow continuous casting billets, meeting the requirements of high-end products.

[0058] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Detailed Implementation

[0059] The following description provides numerous specific details to offer a more thorough understanding of the technical solutions provided by this invention. However, it will be apparent to those skilled in the art that the technical solutions provided by this invention can be implemented without one or more of these details.

[0060] In this embodiment of the invention, the angle at which the ultrasonic probe is inserted into the nozzle refers to the angle between the ultrasonic probe and the horizontal plane.

[0061] In Example 1 of this invention, the aluminum liquid that meets the chemical composition requirements refers to a pure aluminum melt with a mass percentage content of silicon: 0.04%, Fe: 0.18%, and the balance being aluminum, in which all components are stirred evenly.

[0062] In Example 2 of this invention, the alloy aluminum liquid that meets the chemical composition requirements refers to an aluminum-silicon alloy melt with the following mass percentages: silicon: 6.3%, iron ≤ 0.12%, magnesium: 0.03%, titanium: 0.18%, manganese ≤ 0.8%, copper ≤ 0.1%, and the balance being aluminum.

[0063] In Example 3 of this invention, the alloy aluminum liquid that meets the chemical composition requirements refers to an aluminum-silicon-magnesium alloy liquid with the following mass percentages: silicon: 0.7%, iron ≤ 0.12%, magnesium: 0.85%, titanium: 0.05%, manganese ≤ 0.05%, copper ≤ 0.05%, and the balance being aluminum.

[0064] In Example 4 of this invention, the alloy aluminum liquid that meets the chemical composition requirements refers to an aluminum-magnesium alloy liquid with the following mass percentages: silicon: ≤0.1%, iron: ≤0.12%, magnesium: 4.8%, titanium: 0.15%, manganese: 0.12%, chromium: 0.10%, copper: ≤0.05%, and the balance being aluminum.

[0065] In Example 5 of this invention, the alloy aluminum liquid that meets the chemical composition requirements refers to an aluminum-silicon-copper alloy liquid with the following mass percentages: silicon: 7.0%, iron ≤1.0%, magnesium: 0.45%, titanium ≤0.3%, manganese ≤1.0%, copper 3.4%, and the balance being aluminum.

[0066] Example 1

[0067] (1) The pure aluminum melt is smelted and the aluminum melt with the chemical composition meets the requirements. It flows continuously into the continuous casting machine through the flow channel. An intermediate ladle with a capacity of 295 kg of aluminum alloy melt is set at 1100 mm away from the gate on the flow channel.

[0068] (2) The dimensions of the intermediate tundish are designed as follows: length 1350mm, width 300mm, depth 270mm;

[0069] (3) The liquid level of the alloy aluminum liquid in the tundish is 233mm and the amount of aluminum liquid is controlled at 255kg;

[0070] (4) The temperature of the alloy aluminum liquid in the tundish is controlled to be 48°C above the liquidus temperature.

[0071] (5) Set up three ultrasonic pretreatment devices on the tundish to perform ultrasonic pretreatment on the molten aluminum alloy to eliminate gas and impurities in the molten metal and promote the initial formation of crystal nuclei.

[0072] (6) The frequency of the ultrasonic pretreatment device is 20.3-21.4kHz, the power is 800W, and the probe insertion depth is 150mm;

[0073] (7) The pretreated alloy aluminum liquid flows into the continuous casting machine at a rate of 6.4 tons per hour via a small ladle;

[0074] (8) The ultrasonic probe is inserted into the nozzle at a 44-degree angle and the insertion depth is 90mm. The ultrasonic generator outputs a frequency of 19.8-20.2kHz and a power of 500W to perform online grain refinement treatment on the aluminum alloy.

[0075] (9) Cast using continuous casting process to form a cross-sectional area of ​​3400 mm². 2 The trapezoidal billet was cast at a speed of 6.4 t / h, with cooling water pressure controlled at 0.52 MPa and water temperature at 26℃.

[0076] (10) The solidified billet is continuously rolled into a finished product with a specification of 9.5mm;

[0077] (11) The grain size of the solidified billet is grade 5.6.

[0078] Example 2

[0079] (1) The aluminum-silicon alloy melt is smelted and the alloy aluminum melt with the chemical composition meets the requirements is continuously fed into the continuous casting machine through the flow channel. An intermediate ladle with an aluminum alloy melt capacity of 317kg is set on the flow channel at a distance of 1100mm from the gate.

[0080] (2) The dimensions of the intermediate tundish are designed as follows: length 1350mm, width 300mm, depth 290mm;

[0081] (3) The liquid level of the alloy aluminum liquid in the tundish is 230mm and the amount of aluminum liquid is controlled at 252kg;

[0082] (4) The temperature of the molten aluminum alloy in the tundish is controlled to be 53°C above the liquidus temperature;

[0083] (5) Two sets of ultrasonic pretreatment devices are set on the tundish to perform ultrasonic pretreatment on the alloy aluminum liquid to eliminate gas and impurities in the molten metal and promote the initial formation of crystal nuclei.

[0084] (6) The frequency of the ultrasonic pretreatment device is 18.7-19.6kHz, the power is 700W, and the probe insertion depth is 130mm.

[0085] (7) The pretreated alloy aluminum liquid flows into the continuous casting machine at a rate of 6.8 tons per hour through a small ladle;

[0086] (8) The ultrasonic probe is inserted into the nozzle at a 47-degree angle and the insertion depth is 80mm. The ultrasonic generator outputs a frequency of 20.8-21.6kHz and a power of 300W to perform online grain refinement treatment on the aluminum alloy.

[0087] (9) Cast using continuous casting process to form a cross-sectional area of ​​3400 mm². 2 The trapezoidal billet was cast at a speed of 6.8 t / h, with cooling water pressure controlled at 0.48 MPa and water temperature at 28℃.

[0088] (10) The solidified billet is sheared into alloy ingots;

[0089] (11) The grain size of the solidified billet is grade 6.2.

[0090] Example 3

[0091] (1) The aluminum-silicon-magnesium alloy liquid is melted and the alloy aluminum liquid with the chemical composition meets the requirements is continuously flowed into the continuous casting machine through the flow channel. An intermediate ladle with an aluminum alloy liquid capacity of 340kg is set on the flow channel at a distance of 1100mm from the gate.

[0092] (2) The dimensions of the intermediate tundish are designed as follows: length 1350mm, width 300mm, depth 310mm;

[0093] (3) The liquid level of the alloy aluminum liquid in the tundish is 260mm and the amount of aluminum liquid is controlled at 284kg.

[0094] (4) The temperature of the molten aluminum alloy in the tundish is controlled to be 57°C above the liquidus temperature.

[0095] (5) Two sets of ultrasonic pretreatment devices are set on the tundish to perform ultrasonic pretreatment on the alloy aluminum liquid to eliminate gas and impurities in the molten metal and promote the initial formation of crystal nuclei.

[0096] (6) The frequency of the ultrasonic pretreatment device is 19.2-20.5kHz, the power is 600W, and the probe insertion depth is 100mm.

[0097] (7) The pretreated alloy aluminum liquid flows into the continuous casting machine at a rate of 7.0 tons per hour through a small ladle;

[0098] (8) The ultrasonic probe is inserted into the nozzle at a 52-degree angle and the insertion depth is 70mm. The ultrasonic generator outputs a frequency of 21.6-22kHz and a power of 400W to perform online grain refinement treatment on the aluminum alloy.

[0099] (9) Cast using continuous casting process to form a cross-sectional area of ​​3400 mm². 2 The trapezoidal billet was cast at a speed of 7.0 t / h, with cooling water pressure controlled at 0.38 MPa and water temperature at 32℃.

[0100] (10) The solidified billet is continuously rolled into a finished product with a specification of 15mm;

[0101] (11) The grain size of the solidified billet is grade 7.6.

[0102] Example 4

[0103] (1) The aluminum-magnesium alloy liquid is melted and the alloy aluminum liquid with the chemical composition meets the requirements is continuously fed into the continuous casting machine through the flow channel. An intermediate ladle with a capacity of 383kg of aluminum alloy liquid is set at 1100mm away from the gate on the flow channel.

[0104] (2) The dimensions of the intermediate tundish are designed as follows: length 1350mm, width 300mm, depth 350mm;

[0105] (3) The liquid level of the alloy aluminum liquid in the tundish is 300 mm and the amount of aluminum liquid is controlled at 328 kg;

[0106] (4) The temperature of the molten aluminum alloy in the tundish is controlled to be 55°C above the liquidus temperature;

[0107] (5) Set up three ultrasonic pretreatment devices on the tundish to perform ultrasonic pretreatment on the aluminum alloy liquid to eliminate gas and impurities in the molten metal and promote the initial formation of crystal nuclei.

[0108] (6) The frequency of the ultrasonic pretreatment device is 19.9-20.7kHz, the power is 1000W, and the probe insertion depth is 140mm.

[0109] (7) The pretreated alloy aluminum liquid flows into the continuous casting machine at a rate of 6.3 tons per hour via a small ladle;

[0110] (8) The ultrasonic probe is inserted into the nozzle at a 51-degree angle and the insertion depth is 80mm. The ultrasonic generator outputs a frequency of 20.8-21.7kHz and a power of 400W to perform online grain refinement treatment on the aluminum alloy.

[0111] (9) Cast using continuous casting process to form a cross-sectional area of ​​3400 mm². 2 The trapezoidal billet was cast at a speed of 6.3 t / h, with cooling water pressure controlled at 0.33 MPa and water temperature at 30℃.

[0112] (10) The solidified billet is continuously rolled into a finished product with a specification of 9.5mm;

[0113] (11) The grain size of the solidified billet is grade 7.1.

[0114] Example 5

[0115] (1) The aluminum-silicon-copper alloy liquid is melted and the alloy aluminum liquid with the chemical composition meets the requirements is continuously fed into the continuous casting machine through the flow channel. An intermediate ladle with an aluminum alloy liquid capacity of 306kg is set on the flow channel at a distance of 1100mm from the gate.

[0116] (2) The dimensions of the intermediate tundish are designed as follows: length 1350mm, width 300mm, depth 280mm;

[0117] (3) The liquid level of the alloy aluminum liquid in the tundish is 240mm and the amount of aluminum liquid is controlled at 262kg.

[0118] (4) The temperature of the alloy aluminum liquid in the tundish is controlled to be 60°C above the liquidus temperature;

[0119] (5) Two sets of ultrasonic pretreatment devices are set on the tundish to perform ultrasonic pretreatment on the alloy aluminum liquid to eliminate gas and impurities in the molten metal and promote the initial formation of crystal nuclei.

[0120] (6) The frequency of the ultrasonic pretreatment device is 18.6-19.9kHz, the power is 900W, and the probe insertion depth is 90mm.

[0121] (7) The pretreated alloy aluminum liquid flows into the continuous casting machine at a rate of 7.8 tons per hour via a small ladle;

[0122] (8) The ultrasonic probe is inserted into the nozzle at a 46-degree angle and the insertion depth is 90mm. The ultrasonic generator outputs a frequency of 20.4-21.6kHz and a power of 500W to perform online grain refinement treatment on the aluminum alloy.

[0123] (9) Cast using continuous casting process to form a cross-sectional area of ​​3400 mm². 2 The trapezoidal billet was cast at a speed of 7.8 t / h, with cooling water pressure controlled at 0.59 MPa and water temperature at 25℃.

[0124] (10) The solidified billet is sheared into alloy ingots;

[0125] (11) The grain size of the solidified billet is grade 6.3.

[0126] Comparative Example 1

[0127] The difference from Example 1 is that no ultrasonic pretreatment is performed.

[0128] Comparative Example 2

[0129] The difference from Example 2 is that in step (8), the ultrasonic probe is inserted into the nozzle at an angle of 39 degrees to the horizontal plane.

[0130] Comparative Example 3

[0131] The difference from Example 3 is that in step (8), the insertion depth of the ultrasonic probe is 100 mm.

[0132] Comparative Example 4

[0133] The difference from Example 4 is that in step (8), the output frequency of the ultrasonic generator is 19.3 kHz.

[0134] Comparative Example 5

[0135] The difference from Example 5 is that in step (8), the power of the ultrasonic generator is 250W.

[0136] Comparative Example 6

[0137] The difference from Example 5 is that in step (4), the temperature of the molten aluminum alloy in the tundish is controlled to be 48-53°C above the liquidus temperature.

[0138] The test results of each embodiment and comparative example are shown in Table 1:

[0139] Table 1

[0140]

[0141]

[0142] As shown in Table 1:

[0143] Compared to Example 1, Comparative Example 1 did not undergo ultrasonic pretreatment, resulting in a significant increase in average grain size;

[0144] Compared to Example 2, in step (8) of Comparative Example 2, the ultrasonic probe was inserted into the sprue at a 39-degree angle. The hydrogen removal rate of the alloy liquid in Comparative Example 2 decreased significantly, the average grain size increased, the grain size grade decreased after treatment, the resistivity reduction rate decreased from 0.07% to 0.03%, and the main alloy component range reduction rate decreased from 23% to 16%.

[0145] Compared to Example 3, in step (8) of Comparative Example 3, the insertion depth of the ultrasonic probe is 100 mm. The hydrogen removal rate of the alloy liquid in Comparative Example 3 is significantly reduced, the average grain size is significantly increased, the grain size grade after treatment is reduced, the resistivity reduction rate is reduced from 0.08% to 0.01%, and the main alloy component range reduction rate is reduced from 26% to 11%.

[0146] Compared to Example 4, in step (8) of Comparative Example 4, the output frequency of the ultrasonic generator is 19.3kHz. The hydrogen removal rate of the alloy liquid in Comparative Example 4 is significantly reduced, the average grain size is significantly increased, the grain size grade after treatment is reduced, the resistivity reduction rate is reduced from 0.07% to 0, and the main alloy component range reduction rate is reduced from 31% to 7%.

[0147] Compared to Example 5, in step (8) of Comparative Example 5, the power of the ultrasonic generator is 250W. The hydrogen removal rate of the alloy liquid in Comparative Example 5 is significantly reduced, the average grain size is increased, the grain size grade after treatment is reduced, the resistivity reduction rate is reduced from 0.09% to 0, and the main alloy component range reduction rate is reduced from 36% to 6%.

[0148] Compared to Example 5, in step (4) of Comparative Example 6, the temperature of the alloy aluminum liquid in the tundish is controlled at 48-53°C above the liquidus temperature. The hydrogen removal rate of the alloy liquid in Comparative Example 6 is significantly reduced, the average grain size is increased, the grain size grade after treatment is reduced, the resistivity reduction rate is reduced from 0.09% to 0, and the reduction rate of the main alloy component range is reduced from 36% to 11%.

[0149] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for ultrasonic online melt treatment in high-flow-rate continuous casting of aluminum alloys, characterized in that, The processing method includes: 1) Molten aluminum or molten alloy aluminum flows continuously into the continuous casting machine through the flow channel, and an intermediate ladle is set on the flow channel; 2) An ultrasonic pretreatment device is installed on the tundish to perform ultrasonic pretreatment on the molten aluminum or alloy aluminum liquid to eliminate gases and impurities in the molten metal and promote the initial formation of crystal nuclei. 3) Pretreated molten aluminum or alloy molten aluminum flows into the continuous casting machine through a small ladle; 4) The ultrasonic probe is inserted into the sprue at an angle of 40-55 degrees, with an insertion depth of 50-90mm; the output frequency of the ultrasonic generator is 19.8-22kHz and the power is 300-500W, to perform online grain refinement treatment on molten aluminum or alloy aluminum liquid. 5) The billet is cast using a continuous casting process. The solidified billet is then continuously rolled into finished products of different specifications or sheared into alloy ingots.

2. The ultrasonic online melt treatment method for high-flow-rate continuous casting of aluminum alloys according to claim 1, characterized in that, In step 2): The frequency of ultrasonic pretreatment is 18-22kHz; The power of ultrasonic pretreatment is 400-1000W; The insertion depth of the probe of the ultrasonic pretreatment device is 80-150mm.

3. The ultrasonic online melt treatment method for high-flow-rate continuous casting of aluminum alloys according to claim 2, characterized in that, For pure aluminum molten metal: the frequency of ultrasonic pretreatment is 20.3-21.4kHz, the power is 780-820W; the insertion depth of the probe of the ultrasonic pretreatment device is 140-150mm. For molten aluminum-silicon alloy: the frequency of ultrasonic pretreatment is 18.7-19.6kHz, the power is 680-720W; the insertion depth of the probe of the ultrasonic pretreatment device is 120-140mm. For aluminum-silicon-magnesium alloy liquid: the frequency of ultrasonic pretreatment is 19.2-20.5kHz, the power is 580-620W; the insertion depth of the probe of the ultrasonic pretreatment device is 90-110mm. For aluminum-magnesium alloy liquid: the frequency of ultrasonic pretreatment is 19.9-20.7kHz, the power is 950-1000W; the insertion depth of the probe of the ultrasonic pretreatment device is 130-150mm. For aluminum-silicon-copper alloy liquid: the frequency of ultrasonic pretreatment is 18.6-19.9kHz, and the power is 880-920W; the insertion depth of the probe of the ultrasonic pretreatment device is 80-100mm.

4. The ultrasonic online melt treatment method for high-flow-rate continuous aluminum alloy casting according to claim 1, characterized in that, In step 4): For molten pure aluminum: the ultrasonic probe is inserted into the sprue at an angle of 43-45 degrees to a depth of 80-90mm; the output frequency of the ultrasonic generator is 19.8-20.2kHz and the power is 480-500W. For molten aluminum-silicon alloy: the ultrasonic probe is inserted into the nozzle at an angle of 46-48 degrees to a depth of 70-90mm; the output frequency of the ultrasonic generator is 20.8-21.6kHz and the power is 300-320W. For aluminum-silicon-magnesium alloy liquid: the ultrasonic probe is inserted into the nozzle at an angle of 51-53 degrees, with an insertion depth of 60-80mm; the output frequency of the ultrasonic generator is 21.6-22kHz, and the power is 380-420W. For aluminum-magnesium alloy liquid: the ultrasonic probe is inserted into the nozzle at an angle of 50-52 degrees, with an insertion depth of 70-90mm; the output frequency of the ultrasonic generator is 20.8-21.7kHz, and the power is 380-420W; For aluminum-silicon-copper alloy liquid: the ultrasonic probe is inserted into the sprue at an angle of 45-47 degrees, with an insertion depth of 80-90mm; the output frequency of the ultrasonic generator is 20.4-21.6kHz, and the power is 480-500W.

5. The ultrasonic online melt treatment method for high-flow-rate continuous casting of aluminum alloys according to claim 1, characterized in that, The relationship between the temperature T2 of the molten aluminum or alloy aluminum liquid in the tundish and its liquidus temperature T1 is T2 = T1 + (40~60)℃.

6. The ultrasonic online melt treatment method for high-flow-rate continuous casting of aluminum alloys according to claim 5, characterized in that, The relationship between the temperature T2 of the molten aluminum or alloy aluminum liquid in the tundish and its liquidus temperature T1 is as follows: For pure aluminum melt: T2 = T1 + (47~49)℃; For aluminum-silicon alloy melt: T2 = T1 + (52~54)℃; For aluminum-silicon-magnesium alloy melt: T2 = T1 + (56~58)℃; For aluminum-magnesium alloy melt: T2 = T1 + (54~56)℃; For aluminum-silicon-copper alloy liquid: T2 = T1 + (58~60)℃.

7. The ultrasonic online melt treatment method for high-flow-rate continuous casting of aluminum alloys according to claim 1, characterized in that: In step 1), an intermediate tundish is placed on the runner at a distance of 1000-1200mm from the gate. In step 2), 2-3 sets of ultrasonic pretreatment devices are installed on the intermediate package; In step 3), the pretreated molten aluminum or alloy molten aluminum flows into the continuous casting machine at a rate of 6-8 tons per hour via a small ladle.

8. The ultrasonic online melt treatment method for high-flow-rate continuous casting of aluminum alloys according to claim 1, characterized in that, The size and capacity of the intermediate package must satisfy at least one of the following characteristics: The capacity of the intermediate batch is 295-383 kg; The length of the intermediate bag is 1300-1400mm, the width is 280-320mm, and the depth is 270-350mm; The height and volume of molten aluminum within it satisfy at least one of the following characteristics: The liquid level of molten aluminum or alloy aluminum in the tundish is 192-300 mm. The volume of molten aluminum or alloy aluminum in the tundish is 210-328 kg.

9. The ultrasonic online melt treatment method for high-flow-rate continuous aluminum alloy casting according to claim 1, characterized in that, Step 5) satisfies the following characteristics: Cast using continuous casting process to produce cross-sectional areas of 3200-3600 mm² 2 Trapezoidal casting billet; The casting speed is 6.0-8.0 t / h; The cooling water pressure is 0.3-0.6 MPa, and the cooling water temperature is 25-33℃.

10. The ultrasonic online melt treatment method for high-flow-rate continuous casting of aluminum alloys according to claim 1, characterized in that, In step 5), The grain size of the solidified billet is grade 5-8; The average grain size of the solidified billet is ≤45μm.

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