Continuous casting device for hypereutectic aluminum-silicon alloy and preparation method thereof

Abstract

The present invention belongs to the technical field of metal material preparation and application, and specifically discloses a continuous casting device for hypereutectic aluminum silicon alloy, which is composed of a molten pool component and an electromagnetic stirring component used in conjunction with the molten pool component. The beneficial effects of the present invention are: a powdered or granular modifier generates a large number of "heterogeneous" nucleation particles, which serve as the "core" of the crystallization of primary silicon, improve the effective nucleation rate of primary silicon, refine primary silicon, change the morphology of primary silicon, refine the primary silicon structure, reduce the amount of modifier, and reduce the cost; the electromagnetic stirrer and the airflow stir the alloy melt, promote the rapid dispersion and strengthening of the modifier, and promote the temperature field and composition field of the alloy melt to be more uniform; the setting of the powder spraying pipe connected to the powder spraying device avoids the influence of the skin effect of the electromagnetic field, the distribution of the electromagnetic field is more uniform, the temperature field and composition field of the alloy melt are more uniform, and the hypereutectic aluminum silicon alloy melt is processed, which is conducive to obtaining high-quality hypereutectic aluminum silicon alloy billets.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material preparation and application, and in particular relates to a continuous

[0002] Casting device and preparation method thereof. Background Art

[0003] A390 hypereutectic aluminum-silicon alloy billet is usually used to manufacture key parts such as automobile engine pistons, rotors, and swash plates due to its advantages of light weight, high strength, high wear resistance, high heat resistance, and low thermal expansion. Compared with conventional castings, it is not only lighter than ordinary cast iron parts, but also eliminates structural segregation through silicon spheroidization, and obtains uniform structure and fine grains through solid solution treatment, which can significantly improve the mechanical properties and thermal process properties of the alloy. It is widely used in the automotive industry, especially in the application of lightweight automobiles and new energy vehicles.

[0004] Under ordinary casting, primary silicon is generally coarse, in the form of plates, needles and other complex shapes with sharp edges and corners, which seriously splits the matrix, thus reducing the mechanical properties and cutting performance of hypereutectic aluminum-silicon alloy, especially the plasticity is significantly reduced. Therefore, improving the morphology and distribution of primary silicon, refining the size of primary silicon, and reducing its weakening effect on matrix performance are of great significance to improving the comprehensive performance of hypereutectic aluminum-silicon alloy.

[0005] After the addition of supersaturated silicon, the morphology of primary silicon during the re-solidification process has an important influence on the properties of high-silicon aluminum alloys. Its nucleation and growth mechanism and morphological evolution mechanism have always been one of the main research directions of high-silicon aluminum alloys.

[0006] At present, the main preparation methods for defect control of primary silicon in high silicon aluminum alloys include: modifier treatment, semi-solid stirring, rapid solidification, and electric pulse treatment. In the process of powder making, the method of improving the morphology of primary silicon is carried out by optimizing the equipment, but it is difficult to completely control the morphology of primary silicon and make it spheroidized using the existing process. Due to the process characteristics of the A390 aluminum alloy after adding silicon powder under the process conditions, inclusions will inevitably be brought. This defect is the main factor affecting the life of the final product. Previous studies have shown that it is very difficult to completely eliminate inclusions according to the current aluminum alloy preparation process, but the number of inclusions can be reduced by controlling the process parameters. The inclusions of A390 aluminum alloy mainly include metal inclusions and oxide inclusions. Metal inclusions mainly come from particles introduced during the smelting process of the master alloy, and oxide porcelain inclusions are often oxides of Al, Mg, Ca, etc. They come from the slag in the electroslag smelting process of the master alloy, the air and dust impurities that accidentally enter during the addition of silicon powder during processing. The number and size of inclusion defects in the A390 supersaturated aluminum alloy are important factors affecting the safety and reliability of the final product.

[0007] Compared with the United States and Japan, my country still has a huge gap in the research and development of high-purity A390 supersaturated aluminum alloy. Both the preparation of high-purity A390 supersaturated aluminum alloy and its application in the automotive parts industry are restricted by others. Especially in the context of the application of a new generation of lightweight, high-strength and high-wear-resistant aluminum alloys for new energy vehicles, research in this area is still in its infancy. Therefore, it is very meaningful to carry out research on the formation and control of inclusions in A390 supersaturated aluminum alloys.

[0008] As we all know, all materials have magnetism. Magnetism originates from the orbital and spin motion of electrons and the interaction between electrons. According to the behavior of materials to magnetic fields, they can be divided into five categories: diamagnetism, paramagnetism, ferromagnetism, antiferromagnetism and ferrimagnetism. Among them, ferromagnetic and ferrimagnetic materials are usually considered to be magnetic materials, while the other three are called non-magnetic materials due to their weak magnetism. Before the maturity of superconducting magnet technology, ordinary DC magnetic fields were commonly used in the preparation of electromagnetic materials. Due to the low intensity of the magnetic field, its influence on materials is mainly concentrated on magnetic materials, while for non-magnetic materials, it is limited to the macroscopic effect on materials (such as Lorentz force). In the 1980s, with the increasing maturity of low-temperature superconducting technology, the widespread application of superconducting DC strong magnetic fields became possible, which greatly promoted the development of EPM. Different from the macroscopic force of ordinary DC magnetic fields, strong magnetic fields can transfer high-intensity energy without contact and act on the microscopic range of materials, such as changing the arrangement, matching and migration of atoms, thereby having an important impact on the organization and performance of materials. The birth of strong magnetic fields has brought revolutionary changes to the development of EPM in non-magnetic materials. It greatly enhances the generally negligible magnetizing force on non-magnetic materials under ordinary DC magnetic fields, thus having a significant impact on the organizational structure of non-magnetic materials. There are generally two types of magnetizing forces: one is the "orientation" magnetizing force that rotates the material to a certain direction of the magnetic field (similar to a compass pointing to the North Pole), and the other is the "gradient" magnetizing force that attracts ferromagnetic and paramagnetic materials or repels diamagnetic materials. The former is mainly used in crystal arrangement, while the latter is mainly used in magnetic separation, magnetic levitation and measurement of material magnetic susceptibility. Strong magnetic fields have been widely used in various electromagnetic processes of materials, such as alloy solidification, phase change, vapor deposition, electrodeposition and electromagnetic casting, and have gradually developed into a new branch of science called "strong magnetic field material science."

[0009] When a metal alloy is cooled from the liquidus to the "paste zone", the primary crystals will be surrounded by the liquid medium, which means that if an external force is applied at this time, their precipitation behavior can be easily changed. During the solidification process of the alloy with a magnetic field applied, a magnetizing force acting on the primary crystals will be induced, which will have a certain impact on the cast structure of the alloy, and its impact is mainly manifested in the change and migration of crystal orientation.

[0010] Therefore, based on the above problems, the present invention provides a continuous casting device for hypereutectic aluminum-silicon alloy and a preparation method thereof. Summary of the invention

[0011] Purpose of the invention: The purpose of the present invention is to provide a continuous casting device for hypereutectic aluminum-silicon alloy and a preparation method thereof, which has a reasonable design structure, refines the primary silicon structure, reduces the amount of modifier used, and reduces the cost.

[0012] Technical solution: One aspect of the present invention provides a continuous casting device for hypereutectic aluminum-silicon alloy, which is composed of a molten pool component and an electromagnetic stirring component used in conjunction with the molten pool component; the molten pool component includes an outer shell, a vacuum furnace arranged in the outer shell, a rotating electromagnetic stirring hollow shell arranged on the inner wall of the vacuum furnace, a charged coil arranged in the rotating electromagnetic stirring hollow shell, and a solution conduit arranged at the bottom of the outer shell; the electromagnetic stirring component includes a transition molten pool connected to the conduit, and a plurality of L-shaped solution delivery pipes arranged at the bottom of the transition molten pool, and a hollow outer shell respectively arranged on the plurality of L-shaped solution delivery pipes, and a hollow inner shell arranged in the hollow outer shell, and a cold air inlet and a cold air outlet arranged on the hollow outer shell, and auxiliary charged coils, a plurality of circular magnets and a plurality of spiral magnets arranged in sequence between the hollow outer shell and the hollow inner shell from top to bottom; the vacuum furnace is externally connected to a powder spraying pipe and a nitrogen protection conduit, wherein the powder spraying pipe is used to add silicon powder.

[0013] In the technical solution, the length of the solution catheter is 5cm-10cm; the number of the plurality of meander-shaped magnets is four or six; the number of the plurality of spiral magnets is four or six.

[0014] According to the technical solution, the continuous casting device for hypereutectic aluminum-silicon alloy also includes a positioning seat arranged at the top of the outer shell, a vertical external thread adjustment rod arranged on one side of the positioning seat, a transverse ultrasonic detection probe mounting plate fixed on the vertical external thread adjustment rod by a set of locking nuts, and an ultrasonic detection probe arranged in one end of the transverse ultrasonic detection head mounting plate, wherein the ultrasonic detection probe is connected to the ultrasonic detector for detecting the melting state inside the vacuum furnace.

[0015] Another aspect of the present invention provides a continuous casting preparation method for hypereutectic aluminum-silicon alloy, comprising the following steps: step 1, first add an aluminum ingot into a vacuum furnace for melting, then add silicon powder through a powder spraying tube for continuous melting, and introduce nitrogen through a nitrogen protection conduit, and perform preliminary melting electromagnetic treatment with an energized coil; step 2, use an ultrasonic detection probe to detect the melting state of the aluminum ingot and silicon powder in the vacuum furnace in real time; step 3, the smelted mixed liquid enters the transition melt pool through the conduit for pre-insulation treatment; step 4, the mixed liquid in the transition melt pool enters an L-shaped solution feed pipe, and is subjected to electromagnetic forming treatment through an auxiliary energized coil, a plurality of round magnets and a plurality of spiral magnets, wherein during the forming process, the cold air inlet and the cold air outlet are connected to the cold air supply equipment for certain temperature control.

[0016] Compared with the prior art, the continuous casting device for hypereutectic aluminum-silicon alloy and the preparation method thereof of the present invention have the following beneficial effects: 1. The powdered or granular modifier produces a large number of "heterogeneous" nucleation particles, which serve as the "core" of the crystallization of primary silicon, thereby improving the effective nucleation rate of primary silicon, refining primary silicon, changing the morphology of primary silicon, refining the primary silicon structure, reducing the amount of modifier used, and reducing the cost; 2. The electromagnetic stirrer and the airflow stir the alloy melt, which promotes the rapid dispersion and strengthening of the modifier and promotes the temperature field and composition field of the alloy melt to be more uniform; 3. The setting of the powder spraying pipe connected to the powder spraying device avoids the influence of the skin effect of the electromagnetic field, the distribution of the electromagnetic field is more uniform, and the temperature field and composition field of the alloy melt are more uniform. The hypereutectic aluminum-silicon alloy melt is processed, which is conducive to obtaining high-quality hypereutectic aluminum-silicon alloy billets. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a continuous casting device for a hypereutectic aluminum-silicon alloy according to the present invention;

[0018] Figure 2 It is a schematic diagram of the side view of the structure of the transition molten pool and a plurality of L-shaped solution conveying pipes of the continuous casting device for hypereutectic aluminum-silicon alloy of the present invention;

[0019] Figure 3 and Figure 4 The invention is a structural schematic diagram of a positioning seat, a vertical external thread adjustment rod, a set of locking nuts, a transverse ultrasonic detection probe mounting plate, and an ultrasonic detection probe for a continuous casting device for a hypereutectic aluminum-silicon alloy. DETAILED DESCRIPTION

[0020] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. Example

[0021] like Figure 1 , Figure 2 , Figure 3 and Figure 4 The continuous casting device for hypereutectic aluminum-silicon alloy shown in the figure is composed of a molten pool component and an electromagnetic stirring component used in conjunction with the molten pool component; the molten pool component includes an outer shell 1, a vacuum furnace 2 arranged in the outer shell 1, a rotating electromagnetic stirring hollow shell 3 arranged on the inner wall of the vacuum furnace 2, an electrically charged coil 4 arranged in the rotating electromagnetic stirring hollow shell 3, and a solution conduit 7 arranged at the bottom of the outer shell 1; the electromagnetic stirring component includes a transition molten pool 8 connected to the conduit 7, and a A plurality of L-shaped solution delivery pipes 9, and hollow outer shells 10 respectively arranged on the plurality of L-shaped solution delivery pipes 9, and a hollow inner shell 21 arranged in the hollow outer shell 10, and a cold air inlet 11 and a cold air outlet 12 arranged on the hollow outer shell 10, and an auxiliary charged coil 13, a plurality of circular magnets 14 and a plurality of spiral magnets 15 arranged sequentially between the hollow outer shell 10 and the hollow inner shell 21 from top to bottom; the vacuum melting furnace 2 is externally connected to a powder spraying pipe 5 and a protective conduit 6, wherein the powder spraying pipe 5 is used for adding silicon powder.

[0022] Further preferably, the length of the solution conduit 7 is 5cm-10cm; the plurality of circular magnets 17 are arranged in four or six; the plurality of spiral magnets 22 are arranged in four or six; and the continuous casting device for hypereutectic aluminum-silicon alloy also includes a positioning seat 16 arranged at the top of the outer shell 1, and a vertical external thread adjustment rod 17 arranged on one side of the positioning seat 16, and a transverse ultrasonic detection probe mounting plate 18 fixed on the vertical external thread adjustment rod 17 by a set of locking nuts 19, and an ultrasonic detection probe 20 arranged in one end of the transverse ultrasonic detection head mounting plate 18, wherein the ultrasonic detection probe 20 is connected to the ultrasonic detector for detecting the internal melting state of the vacuum furnace 2.

[0023] The continuous casting preparation method for hypereutectic aluminum-silicon alloy of the present invention comprises the following steps: step 1, firstly adding aluminum ingots into a vacuum melting furnace 2 for melting, then adding silicon powder through a powder spraying pipe 5 for continuous melting, and introducing nitrogen through a nitrogen protection conduit 6, and performing preliminary melting electromagnetic treatment with an electrified coil 4; step 2, using an acoustic wave detection probe 20 to detect the melting state of the aluminum ingots and silicon powder in the vacuum melting furnace 2 in real time; step 3, the smelted mixed solution enters a transition melting pool 8 through a conduit 7 for pre-insulation treatment; step 4, the mixed solution in the transition melting pool 8 enters an L-shaped solution feeding pipe 9, and undergoes electromagnetic forming treatment through an auxiliary electrified coil 13, a plurality of serpentine magnets 14 and a plurality of spiral magnets 15, wherein during the forming process, a cold air supply device is connected through a cold air inlet 11 and a cold air outlet 12 to perform certain temperature control.

[0024] The A390 aluminum alloy blank prepared by the present invention has a silicon content of 17.2%, and the modifier used is a powdered aluminum phosphorus modifier with a phosphorus content of 4.5%. Before pouring, the powder spraying device and the modifier are preheated to 300°C (the powder spraying device and the modifier are Figure 1 During the preparation, the A390 aluminum alloy melt at 820°C is introduced into the hot top, and the melt flows to the crystallization through the gap channel for continuous casting; after the continuous casting process is stable, the powder spraying device (powder spraying device) is turned on. Figure 1 Not marked in the figure), the nitrogen pressure blown in is 0.05Mpa, the nitrogen flow rate is 0.1L / min, the powdered modifier input and output is 150g / min, the nominal input power of the electromagnetic stirrer is 1.2kw, the stirring frequency is 40Hz, and the continuous casting process parameters adopted after the continuous casting is stable are: continuous casting speed is 300mm / min, cooling water pressure is 0.35Mpa, and the melt temperature in the gap channel is 740-780℃. At the end of continuous casting, A390 aluminum alloy ingots with fine structure and uniform composition are obtained.

[0025] The continuous casting device for hypereutectic aluminum-silicon alloy of the present invention performs integral continuous casting and adopts an L-type continuous casting process. The melting and solidification equipment is fixed on a vertical plane, and the final product is placed on a horizontal plane, thereby improving production efficiency.

[0026] In the continuous casting device for hypereutectic aluminum-silicon alloy of this structure, the molten metal is first stirred and melted in the one-ton molten pool at the top, and then enters the rectangular transition molten pool (pre-casting insulation pool, the liquid flow in the insulation pool is relatively stable, if it comes directly from a vacuum furnace, the vacuum furnace itself has stirring, and the flow field is chaotic) through a 5 cm channel of the solution conduit below. Silicon powder protected by nitrogen is added to the molten pool and fully stirred, and then a number of L-shaped solution feed pipes (4 small channels, which improve production efficiency, can be 1 to 4 production, etc.) are separated from the rectangular transition molten pool, and finally enter the water cooling solidification and electromagnetic stirring assembly for electromagnetic stirring sequence, first, electromagnetic rotary stirring, the purpose is to get rid of the dendrites of the quenching layer by rotary stirring, which is achieved by an auxiliary charged coil, and the molten metal coming down from the top is quenched when it is connected to the cold air through the cold air inlet 11 and the cold air outlet 12. , dendrites are produced by the quenching, and the dendrites in the quenching layer are thrown off by rotating stirring; second, traveling wave electromagnetic stirring, which is achieved by a number of meandering magnets. The principle is explained as follows: when the broken dendrites thrown out by the first electromagnetic stirring pass through the channel, in order to make the thrown dendrites evenly distributed in the molten pool channel, a driving force must be added to homogenize the broken crystals produced by the cylindrical water-cooled wall in the entire molten pool, and then a horizontal circular traveling wave electromagnetic field is added to diffuse the broken crystals on the circumferential surface to the middle through the thrust of the traveling wave; third, spiral electromagnetic stirring, which is achieved by a number of spiral magnets. After the broken crystals and fine crystals are evenly diffused, the large grains need to be discharged, and an upward spiral electromagnetic stirring is applied. A vertical positive wave is applied. After the wave energy reaches the upper suspension propulsion force of the particles, the particles will automatically exclude the interface to be solidified upward, thereby achieving the ultimate goal of optimizing the organization.

[0027] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention. These improvements should also be regarded as within the scope of protection of the present invention.

Claims

1. A continuous casting device for hypereutectic aluminum-silicon alloy, characterized in that: The invention is composed of a molten pool component and an electromagnetic stirring component used in conjunction with the molten pool component; the molten pool component comprises an outer shell (1), a vacuum melting furnace (2) arranged in the outer shell (1), a rotating electromagnetic stirring hollow shell (3) arranged on the inner wall of the vacuum melting furnace (2), an electric coil (4) arranged in the rotating electromagnetic stirring hollow shell (3), and a solution conduit (7) arranged at the bottom of the outer shell (1); the electromagnetic stirring component comprises a transition molten pool (8) connected to the solution conduit (7), a plurality of L-shaped solution delivery pipes (9) arranged at the bottom of the transition molten pool (8), and hollow shells (10) respectively arranged on the plurality of L-shaped solution delivery pipes (9), and a plurality of L-shaped solution delivery pipes (9) arranged at the bottom of the transition molten pool (8). A hollow inner shell (21) inside the hollow outer shell (10), a cold air inlet (11) and a cold air outlet (12) arranged on the hollow outer shell (10), and an auxiliary charged coil (13), a plurality of circular magnets (14) and a plurality of spiral magnets (15) arranged in sequence from top to bottom between the hollow outer shell (10) and the hollow inner shell (21); the vacuum melting furnace (2) is externally connected to a powder spraying pipe (5) and a nitrogen protection conduit (6), wherein the powder spraying pipe (5) is used for adding silicon powder; the length of the solution conduit (7) is 5 cm-10 cm; four or six of the plurality of circular magnets (14) are arranged; and four or six of the plurality of spiral magnets (15) are arranged; It also includes a positioning seat (16) arranged at the top of the housing (1), a vertical external thread adjustment rod (17) arranged on one side of the positioning seat (16), a transverse ultrasonic detection probe mounting plate (18) fixed to the vertical external thread adjustment rod (17) via a set of locking nuts (19), and an ultrasonic detection probe (20) arranged in one end of the transverse ultrasonic detection probe mounting plate (18), wherein the ultrasonic detection probe (20) is connected to an ultrasonic detector and is used to detect the internal melting state of the vacuum furnace (2).

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