A large flow aluminum alloy continuous casting ultrasonic online melt treatment method

Abstract

The present application 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 following steps: 1) continuously flowing molten aluminum or alloy molten aluminum into a continuous casting machine through a flow channel, and arranging a tundish on the flow channel; 2) performing ultrasonic pretreatment on the molten aluminum or alloy molten aluminum; 3) flowing the pretreated molten aluminum or alloy molten aluminum into the continuous casting machine through a small ladle; 4) performing online grain refinement treatment; and 5) casting into a casting blank by using a continuous casting process. The present application solves the problems of poor grain refinement effect, insufficient purity, poor composition uniformity and the like in the existing large-flow aluminum alloy continuous casting process, realizes micron-level grain refinement, and makes the average grain size reach below 45 μm and the grain size grade reach above 5.5.

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 nozzle at an angle of 40-55 degrees, and the insertion depth is 50-90 mm; the output frequency of the ultrasonic generator is 19.8-22 kHz, and the power is 300-500 W, so as to perform online grain refinement treatment on the aluminum melt or alloy melt;

[0012] 5) the continuously cast ingot is continuously rolled into finished products of different specifications, or is cut into alloy ingots.

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

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

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

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

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

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

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

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

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

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

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

[0024] As a preferred solution, in step 4) of the above-mentioned large-flow aluminum alloy continuous casting ultrasonic on-line melt treatment method:

[0025] For pure aluminum melt: the ultrasonic probe is inserted into the nozzle at an angle of 43-45 degrees, and the insertion depth is 80-90 mm; the output frequency of the ultrasonic generator is 19.8-20.2 kHz, and the power is 480-500 W, and the grain size of the solidified and formed casting blank can reach 5.6 levels;

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

[0027] For aluminum-silicon-magnesium alloy melt: the ultrasonic probe is inserted into the nozzle at an angle of 51-53 degrees, and the insertion depth is 60-80 mm; the output frequency of the ultrasonic generator is 21.6-22 kHz, and the power is 380-420 W, and the grain size of the solidified and formed casting blank can reach 7.6 levels;

[0028] For aluminum-magnesium alloy melt: the ultrasonic probe is inserted into the nozzle at an angle of 50-52 degrees, and the insertion depth is 70-90 mm; the output frequency of the ultrasonic generator is 20.8-21.7 kHz, and the power is 380-420 W, and the grain size of the solidified and formed casting blank can reach 7.1 levels;

[0029] For aluminum-silicon-copper alloy melt: the ultrasonic probe is inserted into the nozzle at an angle of 45-47 degrees, and the insertion depth is 80-90 mm; the output frequency of the ultrasonic generator is 20.4-21.6 kHz, and the power is 480-500 W, and the grain size of the solidified and formed casting blank can reach 6.3 levels.

[0030] As a preferred solution, in the above-mentioned large-flow aluminum alloy continuous casting ultrasonic on-line melt treatment method, the relationship between the temperature T2 of the aluminum melt or alloy aluminum melt in the tundish and the liquidus temperature T1 thereof is T2 = T1 + (40-60) °C. Further preferably:

[0031] For pure aluminum melt: T2 = T1 + (47-49) °C;

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

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

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

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

[0036] As a preferred solution, in step 1) of the above-mentioned large-flow aluminum alloy continuous casting ultrasonic online melt treatment method, the tundish is provided with an intermediate ladle at a position 1000-1200 mm away from the nozzle opening.

[0037] As a preferred solution, in step 2) of the above-mentioned large-flow aluminum alloy continuous casting ultrasonic online melt treatment method, the tundish is provided with 2-3 sets of ultrasonic pretreatment devices.

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

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

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

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

[0042] The height of the aluminum liquid and the amount of aluminum liquid therein meet at least one of the following characteristics:

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

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

[0045] In order to achieve the purpose of better grain refinement.

[0046] As a preferred solution, step 5) of the above-mentioned large-flow aluminum alloy continuous casting ultrasonic online melt treatment method meets the following characteristics:

[0047] The continuous casting process is used to cast a trapezoidal billet with a cross-sectional area of 3200-3600 mm 2 ;

[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 °C.

[0050] According to the present application, the grain size of the solidified and shaped billet prepared by the above-mentioned method is 5-8 levels.

[0051] According to the present application, the average grain size of the continuously cast billet prepared by the above method is less than or equal to 45 microns.

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

[0053] 1. The uniformity of alloy composition is improved, and the internal structure is uniform.

[0054] 2. The hydrogen content in the alloy liquid is reduced, the purity of the alloy is improved, and a continuously cast billet with good physical and chemical properties is obtained.

[0055] 3. The grain size grade of the continuously cast billet is obviously improved, micron-level grain refinement is achieved, the average grain size is less than or equal to 45 microns, and the grain size grade is greater than or equal to 5.5.

[0056] 4. The electrical conductivity of the product is improved.

[0057] 5. After using this technology, the quality of large-flow continuously cast billets is greatly improved, and can meet the use requirements of high-end products.

[0058] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, and can be implemented according to the content of the specification, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. DETAILED DESCRIPTION

[0059] In the following description, a large number of specific details are given in order to provide a more thorough understanding of the technical solutions provided by the present application. However, it is obvious to those skilled in the art that the technical solutions provided by the present application can be implemented without one or more of these details.

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

[0061] In the embodiment 1 of the present application, the molten aluminum with chemical composition meeting the requirements refers to a pure aluminum melt with uniform stirring of each component, with mass percentage of silicon: 0.04%, Fe: 0.18%, and the balance being aluminum.

[0062] In the embodiment 2 of the present application, the alloyed molten aluminum with chemical composition meeting the requirements refers to an aluminum-silicon alloy melt with mass percentage of silicon: 6.3%, Fe: 0.12%, magnesium: 0.03%, titanium: 0.18%, manganese: 0.8%, copper: 0.1%, and the balance being aluminum.

[0063] In the embodiment 3 of the present application, the alloy liquid aluminum with the required chemical composition refers to the aluminum silicon magnesium alloy liquid with the mass percentage of silicon 0.7%, iron ≤0.12%, magnesium 0.85%, titanium 0.05%, manganese ≤0.05%, copper ≤0.05%, and the rest of aluminum.

[0064] In the embodiment 4 of the present application, the alloy liquid aluminum with the required chemical composition refers to the aluminum magnesium alloy liquid with the mass percentage of silicon ≤0.1%, iron ≤0.12%, magnesium 4.8%, titanium 0.15%, manganese 0.12%, chromium 0.10%, copper ≤0.05%, and the rest of aluminum.

[0065] In the embodiment 5 of the present application, the alloy liquid aluminum with the required chemical composition refers to the aluminum silicon copper alloy liquid with the mass percentage of silicon 7.0%, iron ≤1.0%, magnesium 0.45%, titanium ≤0.3%, manganese ≤1.0%, copper 3.4%, and the rest of aluminum.

[0066] Embodiment 1

[0067] (1) The pure aluminum liquid is treated by smelting, and the aluminum liquid with the required chemical composition is continuously flowed into the continuous casting machine through the flow channel, and the intermediate ladle with the alloy liquid capacity of 295 kg is arranged at the position 1100 mm away from the nozzle on the flow channel;

[0068] (2) The size of the intermediate ladle is designed as: length 1350 mm, width 300 mm, and depth 270 mm;

[0069] (3) The height of the alloy liquid aluminum in the intermediate ladle is 233 mm, and the amount of the aluminum liquid is controlled to be 255 kg;

[0070] (4) The temperature of the alloy liquid aluminum in the intermediate ladle is controlled to be 48 ℃ above the liquidus temperature;

[0071] (5) Three sets of ultrasonic pretreatment devices are arranged on the intermediate ladle, and the alloy liquid aluminum is subjected to ultrasonic pretreatment to eliminate the gas and impurities in the molten metal and promote the preliminary formation of the crystal nucleus;

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

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

[0074] (8) The ultrasonic probe is inserted into the nozzle at the angle of 44 degrees, the insertion depth is 90 mm, the output frequency of the ultrasonic generator is 19.8-20.2 kHz, the power is 500 W, and the aluminum alloy is subjected to the online grain refinement treatment;

[0075] (9) the continuously cast process is used to cast a trapezoidal casting blank with a cross-sectional area of 3400 mm 2 , the casting speed is controlled at 6.4 t / h, and the cooling water pressure is controlled at 0.52 MPa, and the water temperature is 26℃;

[0076] (10) the solidification-molded casting blank is continuously rolled into a finished product with a specification of 9.5 mm;

[0077] (11) the solidification-molded casting blank has a grain size of 5.6.

[0078] Example 2

[0079] (1) the aluminum-silicon alloy melt is subjected to a smelting treatment, and the alloy melt with a chemical composition meeting the requirements is continuously fed into a continuous casting machine through a runner, and an intermediate ladle with an aluminum alloy liquid capacity of 317 kg is arranged at a position 1100 mm away from the nozzle opening on the runner;

[0080] (2) the intermediate ladle has a size designed as follows: length 1350 mm, width 300 mm, and depth 290 mm;

[0081] (3) the height of the alloy aluminum liquid surface in the intermediate ladle is 230 mm, and the amount of the aluminum liquid is controlled at 252 kg;

[0082] (4) the temperature of the alloy aluminum liquid in the intermediate ladle is controlled at 53℃ above the liquidus temperature;

[0083] (5) two sets of ultrasonic pretreatment devices are arranged on the intermediate ladle to perform ultrasonic pretreatment on the alloy aluminum liquid to eliminate gas and impurities in the molten metal and promote the preliminary formation of crystal nuclei;

[0084] (6) the frequency of the ultrasonic pretreatment device is 18.7-19.6 kHz, the power is 700 W, and the probe is inserted to a depth of 130 mm;

[0085] (7) the pretreated alloy aluminum liquid is fed 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 opening at an angle of 47 degrees and to a depth of 80 mm, and the ultrasonic generator outputs a frequency of 20.8-21.6 kHz and a power of 300 W to perform online grain refinement treatment on the aluminum alloy;

[0087] (9) the continuously cast process is used to cast a trapezoidal casting blank with a cross-sectional area of 3400 mm 2 , the casting speed is controlled at 6.8 t / h, and the cooling water pressure is controlled at 0.48 MPa, and the water temperature is 28℃;

[0088] (10) the solidification-molded casting blank is sheared into an alloy ingot;

[0089] (11) The grain size of the solidified and shaped casting blank is 6.2.

[0090] Example 3

[0091] (1) The aluminum-silicon-magnesium alloy liquid is treated by smelting, and the alloy aluminum liquid with the required chemical composition is continuously fed into the continuous casting machine through the flow channel. An intermediate ladle with an aluminum alloy liquid capacity of 340 kg is arranged at a position 1100 mm away from the nozzle on the flow channel;

[0092] (2) The size of the intermediate ladle is designed as follows: length 1350 mm, width 300 mm, and depth 310 mm;

[0093] (3) The height of the alloy aluminum liquid in the intermediate ladle is 260 mm, and the amount of the aluminum liquid is controlled to be 284 kg;

[0094] (4) The temperature of the alloy aluminum liquid in the intermediate ladle is controlled to be 57°C above the liquidus temperature;

[0095] (5) Two sets of ultrasonic pretreatment devices are arranged on the intermediate ladle to pretreat the alloy aluminum liquid by ultrasonic waves to eliminate the gas and impurities in the molten metal and promote the preliminary formation of crystal nuclei;

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

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

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

[0099] (9) The continuous casting process is used to cast a trapezoidal casting blank with a cross-sectional area of 3400 mm 2 . The casting speed is controlled at 7.0 t / h, the cooling water pressure is controlled at 0.38 MPa, and the water temperature is 32°C;

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

[0101] (11) The grain size of the solidified and shaped casting blank is 7.6.

[0102] Example 4

[0103] (1) The aluminum-magnesium alloy liquid is treated by smelting, and the alloy aluminum liquid with the required chemical composition is continuously fed into the continuous casting machine through the flow channel. An intermediate ladle with an aluminum alloy liquid capacity of 383 kg is arranged at a position 1100 mm away from the nozzle on the flow channel;

[0104] (2) The intermediate ladle is designed with a length of 1350 mm, a width of 300 mm, and a depth of 350 mm;

[0105] (3) The alloy liquid aluminum in the intermediate ladle has a liquid level height of 300 mm, and the aluminum liquid volume is controlled to be 328 kg;

[0106] (4) The alloy liquid aluminum in the intermediate ladle is controlled to have a temperature of 55℃ above the liquidus temperature;

[0107] (5) Three sets of ultrasonic pretreatment devices are arranged on the intermediate ladle to perform ultrasonic pretreatment on the aluminum alloy liquid to eliminate gas and impurities in the molten metal and promote the preliminary formation of crystal nuclei;

[0108] (6) The ultrasonic pretreatment device has a frequency of 19.9-20.7 kHz and a power of 1000 W, and the probe is inserted to a depth of 140 mm;

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

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

[0111] (9) The continuous casting process is used to cast a trapezoidal billet with a cross-sectional area of 3400 mm 2 , the casting speed is controlled at 6.3 t / h, the cooling water pressure is controlled at 0.33 MPa, and the water temperature is 30℃;

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

[0113] (11) The solidified and formed billet has a grain size of 7.1 grade.

[0114] Example 5

[0115] (1) The aluminum-silicon-copper alloy liquid is treated by melting, and the alloy liquid with a chemical composition meeting the requirements continuously flows into the continuous casting machine through the flow channel. An intermediate ladle with an aluminum alloy liquid capacity of 306 kg is arranged on the flow channel 1100 mm away from the nozzle;

[0116] (2) The intermediate ladle is designed with a length of 1350 mm, a width of 300 mm, and a depth of 280 mm;

[0117] (3) The alloy liquid aluminum in the intermediate ladle has a liquid level height of 240 mm, and the aluminum liquid volume is controlled to be 262 kg;

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

[0119] (5) Two sets of ultrasonic pretreatment devices are arranged on the tundish to pretreat the molten alloy with ultrasonic waves to eliminate the gas and impurities in the molten metal and promote the preliminary formation of crystal nucleus;

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

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

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

[0123] (9) The continuous casting process is used to cast a trapezoidal billet with a cross-sectional area of 3400 mm 2 , the casting speed is controlled at 7.8 t / h, the cooling water pressure is controlled at 0.59 MPa, and the water temperature is 25°C;

[0124] (10) The solidified and formed billet is cut into alloy ingots;

[0125] (11) The grain size of the solidified and formed billet is 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 250 W.

[0136] Comparative Example 6

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

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

[0139] Table 1

[0140]

[0141]

[0142] From Table 1, it can be seen that:

[0143] Compared with Example 1, Comparative Example 1 does not perform ultrasonic pretreatment, resulting in a significant increase in the average grain size;

[0144] Compared with Example 2, in step (8) of Comparative Example 2, the ultrasonic probe is inserted into the nozzle opening at an angle of 39 degrees, and the hydrogen removal rate of the alloy liquid of Comparative Example 2 decreases significantly, the average grain size increases, the grain size grade after treatment decreases, the resistivity reduction rate decreases from 0.07% to 0.03%, and the main alloy component range reduction rate decreases from 23% to 16%;

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

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

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

[0148] In step (4) of Comparative Example 6, the temperature of the molten alloy in the tundish was controlled to be 48-53 °C above the liquidus temperature, and the hydrogen removal rate of the molten alloy of Comparative Example 6 was significantly decreased, the average grain size was increased, the grain size grade after treatment was decreased, the resistivity reduction rate was decreased from 0.09% to 0, and the extreme difference reduction rate of the main alloying components was decreased from 36% to 11%.

[0149] The preferred embodiments of the present application have been described above with the purpose not to limit the present application but to more fully and completely reveal the application. Those skilled in the art will further appreciate that various modifications, adaptations, and variations of the preferred embodiments can be made and that such modifications, adaptations, variations are intended to be within the spirit and scope of the present application. Accordingly, the patent is intended to cover all adaptations and variations of the preferred embodiments.

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 gas 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 cut into alloy ingots. In step 2), for pure aluminum melt: 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. In step 2), for aluminum-silicon alloy melt: 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. In step 2), 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. In step 2), 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. In step 2), for aluminum-silicon-copper alloy liquid: the frequency of ultrasonic pretreatment is 18.6-19.9kHz, the power is 880-920W; the insertion depth of the probe of the ultrasonic pretreatment device is 80-100mm. 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 80-90 mm; the output frequency of the ultrasonic generator is 19.8-20.2 kHz and the power is 480-500 W. In step 4), for molten aluminum-silicon alloy: the ultrasonic probe is inserted into the nozzle 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. In step 4), for the aluminum-silicon-magnesium alloy liquid: the ultrasonic probe is inserted into the nozzle at an angle of 51-53 degrees, and the insertion depth is 60-80mm; the output frequency of the ultrasonic generator is 21.6-22kHz and the power is 380-420W. In step 4), for the aluminum-magnesium alloy liquid: the ultrasonic probe is inserted into the nozzle at an angle of 50-52 degrees, and the insertion depth is 70-90mm; the output frequency of the ultrasonic generator is 20.8-21.7kHz and the power is 380-420W. In step 4), for the aluminum-silicon-copper alloy liquid: the ultrasonic probe is inserted into the nozzle at an angle of 45-47 degrees, and the insertion depth is 80-90mm; the output frequency of the ultrasonic generator is 20.4-21.6kHz and the power is 480-500W. 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 molten aluminum-silicon alloy: 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)℃.

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 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.

3. The ultrasonic online melt treatment method for high-flow-rate continuous aluminum alloy casting 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.

4. 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℃.

5. 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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