Method and apparatus for multi-stream sequential alloying and density purification of magnesium alloy ingots

Abstract

The application discloses a magnesium alloy multi-liquid flow sequential alloying and clean density ingot casting method and device, and belongs to the technical field of magnesium alloy smelting. The device comprises a furnace body, a plurality of smelting components, a smelting component comprising a crucible and a heating component, the top of the crucible being communicated with an alloy liquid guide-in pipe, a hot-state protective gas guide-in pipe, an alloy liquid guide-out pipe and a vent valve; the bottom of the crucible is provided with a slag outlet; the outer side of the crucible is provided with the heating component; a slag removal component is arranged at the bottom of the crucible, the slag removal component comprising a slag liquid separator and a slag filter plate, the slag liquid separator being communicated with the alloy liquid guide-out pipe; a hot-state protection component comprising a gas heater, a hot-state gas air distribution device and an air inlet; a clean density ingot casting component comprising an intermediate cabin, a crystallizer, a cooling device and an ingot guide. The magnesium alloy multi-liquid flow sequential alloying and clean density ingot casting device can effectively guarantee the alloy ingot quality in the whole process without significantly changing the existing device configuration and cost input.

Description

Technical Field

[0001] This invention relates to the field of magnesium alloy smelting technology, and more specifically to a method and apparatus for magnesium alloy multi-flow sequential alloying and net-density casting ingots. Background Technology

[0002] Magnesium alloys are the lightest metallic structural materials, and their application potential in lightweight transportation equipment is enormous. Magnesium alloys are of great significance in lightweight applications. Semi-continuous casting is the main raw material for processing and forming the aforementioned deformed magnesium alloy load-bearing structural components. Through reasonable plastic forming processes of semi-continuous casting, such as extrusion, rolling, and forging, long extruded profiles, rolled plates, and volume-formed components can be formed, effectively supporting the manufacturing process of lightweight equipment.

[0003] Clean and dense casting, which ensures the cleanliness and density of magnesium alloys during solidification, is a fundamental technical guarantee for the large-scale industrial application of magnesium alloys. The stable and efficient achievement of clean and dense casting is of great significance to the semi-continuous casting process of magnesium alloys. It can be reasonably expected that the quality of subsequent heat treatment strengthening and plastic forming (such as extrusion, rolling, forging, etc.) will be steadily improved, promoting the downstream application of magnesium alloys.

[0004] Existing industrial magnesium alloy ingot casting technology generally adopts a semi-continuous casting method. However, due to insufficient understanding of the intrinsic properties of magnesium alloys, such as the fact that the entire magnesium alloy casting process is generally extremely sensitive to the casting environment and is prone to the formation of related environmental products that degrade the ingot properties, the yield of magnesium alloy ingots is generally low and unstable. This results in high production costs, which is not conducive to the quality design and application promotion of magnesium alloys.

[0005] Most conventional ingot casting systems employ a "single-flow mixed casting" method, where pure magnesium and all alloying materials are melted uniformly in a single crucible, and then the alloyed melt is transferred to a solidification apparatus for solidification via pipetting or crucible tilting (see reference). Figure 1 (Left figure in the image). The above scheme is more suitable for alloy systems containing only independent components. Generally, flux-assisted purification is carried out simultaneously with the alloying process. However, it is easy to introduce unremoved impurities or excessive flux into the casting process, which may remain in the final alloy product and affect its performance.

[0006] Furthermore, if reactive components are present, especially the second phase with a density greater than the average density of the melt, they may settle to the bottom of the crucible, or the flux may adsorb and mix with the settled oxide inclusions to form bottom slag, which will prevent the reactive components from effectively entering the solidified ingot. As a result, the composition and components of the final ingot will not match the design, and the precise alloying effect cannot be achieved. Summary of the Invention

[0007] To address the above problems, this invention proposes an industrial magnesium alloy clean and dense ingot casting method and apparatus based on the inherent characteristics of magnesium and magnesium alloy materials, such as the easy oxidation of high-temperature melts. Without significantly changing the existing equipment configuration and cost, it can effectively ensure the quality of alloy ingots throughout the entire process. In particular, it significantly improves the removal of oxide inclusions in magnesium alloy melts and the precise design of alloying, realizing the high-quality design and application of magnesium alloy ingots.

[0008] The first objective of this invention is to provide a magnesium alloy multi-flow sequential alloying clean casting ingot apparatus, comprising a furnace body, and further comprising:

[0009] Multiple fusion components are provided, each including a crucible and a heating component. The top of the crucible is connected to one end of an alloy liquid inlet pipe, one end of a hot protective gas inlet pipe, one end of an alloy liquid outlet pipe, and one end of a vent valve. The bottom of the crucible is provided with a slag outlet. The heating component is located on the outside of the crucible.

[0010] A slag removal assembly is located at the bottom of the crucible. The slag removal assembly includes a slag-liquid separator and a filter plate. The slag-liquid separator is connected to one end of the alloy liquid outlet pipe. The filter plate is connected to the side wall of the alloy liquid outlet pipe.

[0011] A thermal protection component includes a gas heater, a thermal gas distribution device, and an air inlet; the air inlet is located at the bottom of the gas heater and is connected to the gas heater, the gas heater is connected to the other end of the thermal protection gas inlet pipe; the thermal gas distribution device is connected to the thermal protection gas inlet pipe.

[0012] The clean-dense ingot casting assembly includes an intermediate chamber, a crystallizer, a cooling device, and an ingot deriver. The other end of the alloy liquid outlet pipe is connected to the intermediate chamber. The hot gas distribution device is arranged around the intermediate chamber. The bottom of the intermediate chamber is connected to the crystallizer. The crystallizer is equipped with a cooling device. The ingot deriver is located at the bottom of the crystallizer.

[0013] In one embodiment of the present invention, the sludge-liquid separator includes an upper circular assembly and a lower circular assembly;

[0014] The upper circular component includes an inner circular structural support plate, an upper base plate, multiple outer diversion ribs, multiple inner diversion ribs, and a filter screen. The inner circular structural support plate is fixedly connected to the upper base plate. The upper base plate has a liquid outlet at its center. The upper circular component is connected to one end of the alloy liquid outlet pipe through the liquid outlet. Multiple inner diversion ribs and multiple outer diversion ribs are arranged in a ring from the inside to the outside of the upper base plate with the liquid outlet as the center. The filter screen is inserted between the multiple inner diversion ribs and between the multiple outer diversion ribs.

[0015] The lower circular component includes an outer circular structural support plate, a groove plate, and a lower base plate; the outer circular structural support plate is fixedly connected to the lower base plate, the lower base plate is provided with multiple liquid inlets, and the groove plate is fixedly connected to the lower base plate;

[0016] The inner circular structural support plate is fastened together with the outer circular structural support plate.

[0017] In one embodiment of the present invention, the filter plate is connected to the side wall of the alloy liquid outlet pipe via a connecting rod; the filter plate is provided with filter holes, liquid inlet holes and a rotating cover, the rotating cover is rotatably connected to the filter plate, and the rotation of the rotating cover realizes the sealing and opening of the liquid inlet holes.

[0018] In one embodiment of the present invention, the crystallizer is provided with a graphite forming channel;

[0019] The cooling device includes a water-cooled pipeline and a spray device. The water-cooled pipeline is located on the inner wall of the graphite forming channel, and the spray device is located on the circumferential side of the lower end of the graphite forming channel of the crystallizer.

[0020] In one embodiment of the present invention, the crucible includes a crucible body and a steel furnace lid. The crucible body, from the outside to the inside, includes a steel pot body, a steel hoisting frame, a heat-conducting buffer pad, and a high-purity, high-density graphite crucible chamber.

[0021] In one embodiment of the present invention, the alloy liquid inlet pipe, the alloy liquid outlet pipe, and the hot protective gas inlet pipe are all provided with a heat insulation layer.

[0022] A second objective of this invention is to provide a method for mass-casting magnesium alloy multi-flow sequential alloying ingots, based on the aforementioned mass-casting ingot apparatus, comprising the following steps:

[0023] Before loading, the alloy liquid inlet pipe and alloy liquid outlet pipe are heated by electric heating so that the pipe wall temperature is more than 50°C higher than the alloy melting point.

[0024] Cold inert gas enters the gas heater through the inlet, heating the gas temperature to 600-800℃, and then enters the crucible through the hot gas inlet pipe to form a hot inert gas protective atmosphere; the hot gas distribution device is used to protect the surface of the magnesium alloy melt in the intermediate chamber and crystallizer from oxidation contamination and low temperature environment.

[0025] Multiple magnesium alloy raw materials to be melted are placed in multiple crucibles and smelted in a hot inert gas protective atmosphere to form a partially alloyed melt. Then, a slag separator, a slag filter plate and an alloy melt outlet pipe are connected and lowered to the bottom of the crucible to remove slag from the partially alloyed melt, thereby obtaining multiple pure partially alloyed melts.

[0026] Multiple pure partially alloyed melts are fed into the alloy liquid inlet pipe of the final alloying crucible through multiple alloy liquid outlet pipes. They are then mixed inside the crucible. A slag separator and a slag filter plate are connected to the alloy liquid outlet pipe and lowered to the bottom of the crucible to remove slag from the partially alloyed melts, thus obtaining the final magnesium alloy melt.

[0027] Finally, the magnesium alloy melt is sequentially transported to the intermediate chamber through the alloy liquid outlet pipe; then it flows into the crystallizer, is cooled by the cooling device, solidifies and is pulled out by the ingot puller, and the ingot is cooled a second time during the pulling process.

[0028] In one embodiment of the present invention, the magnesium alloy raw material is high-purity magnesium with a purity > 99.98%, high-purity zinc with a purity > 99.99%, and high-purity aluminum with a purity > 99.99%.

[0029] In one embodiment of the present invention, the inert gas is argon with a purity of 99.999% or higher.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] Based on the intrinsic functional properties of magnesium and magnesium alloys, this invention designs a "low-oxidation inclusion full-process quality improvement technology" for industrial magnesium alloys, which realizes the formation of clean and dense ingots and can significantly improve the service performance of the substrate in downstream heat treatment strengthening, plastic forming manufacturing and surface protection processes.

[0032] This invention first combines and melts some independent components, and removes impurities through the process to ensure a pure partial alloying solution. Then, the purified alloying solutions are cast according to the designed reaction sequence. During the casting process, the designed reaction components are generated and uniformly dispersed in the sequentially cast mixed melt, ensuring the final preparation of pure magnesium alloy raw materials with precise controllable alloy components and uniform and dense structure.

[0033] This invention incorporates a slag removal device. After the material is completely melted to form a partially alloyed melt, the slag-liquid separator and filter plate are connected together with the alloy melt outlet pipe and lowered to the bottom of the crucible. On one hand, the filter plate removes large-sized slag, specifically through evenly distributed filter holes. On the other hand, the slag-liquid separator performs secondary filtration. Specifically, the outer and inner diversion ribs are evenly distributed in a ring, and secondary slag removal is achieved through filter screens inserted in the interval areas of the same layer of diversion ribs. This invention can effectively and promptly remove primary oxides, process oxide inclusions, and other impurities brought in by the material during the smelting process through the slag removal device. Attached Figure Description

[0034] Figure 1 A comparative schematic diagram of single-flow mixed casting (left) and multi-flow sequential casting (right);

[0035] Figure 2 Schematic diagram of an industrial magnesium alloy net-density casting ingot system;

[0036] Figure 3 This is a schematic diagram of the sludge-liquid separator.

[0037] Figure 4 This is a schematic diagram of the three-dimensional structure of the lower circular component;

[0038] Figure 5 This is a schematic diagram of the cross-sectional structure of the lower circular component;

[0039] Figure 6 This is a schematic diagram of the three-dimensional structure of the upper circular component;

[0040] Figure 7 This is a schematic diagram of the cross-sectional structure of the upper circular component;

[0041] Figure 8 This is a schematic diagram of the filter plate structure;

[0042] Figure 9 A schematic diagram illustrating the working principle of the slag removal chamber for fusion;

[0043] Figure 10 The images show a physical diagram of the crystallizer (a), a physical diagram of the spray nozzle (b), a structural schematic diagram of the crystallizer (c), and a structural schematic diagram of the pull-out ingot device (d).

[0044] Figure 11 The figures show a comparison of corrosion rates of AZ80 magnesium alloys with different purities. (a) The figure shows the hydrogen evolution curves of as-cast AZ80A with different purities; (b) The figure shows the corrosion rate and corrosion morphology of as-cast AZ80A with different purities.

[0045] Figure reference numerals: 1. Alloy liquid inlet pipe; 2. Insulation layer; 3. Alloy liquid outlet pipe; 4. Hot gas inlet pipe; 5. Vent valve; 6. Steel furnace cover; 7. Steel pot body; 8. Steel hoisting frame; 9. Thermally conductive buffer pad; 10. High-purity, high-density graphite crucible; 11. Resistance wire winding; 12. Alloying melt; 13. Connecting rod; 14. Slag-liquid separator; 14-1. Outer circular structural support plate; 14-2. Liquid inlet trough plate; 14-3. Trough plate; 14-4. Inner circular structural support plate; 14-5. External diversion. Ribs, 14-6 Internal diversion ribs, 14-7 Filter screen, 14-8 Liquid outlet, 15-Filter slag plate, 15-1 Connection point, 15-2 Rotary cover, 15-3 Fixed pin, 15-4 Liquid inlet hole, 15-5 Filter slag hole, 16 Slag outlet, 17 Gas heater, 18 Air inlet, 19 Intermediate chamber, 20 Hot gas distribution device, 21 Water cooling pipeline, 22 Crystallizer, 23 Graphite forming channel, 24 Spray device, 25 Ingot, 26 Ingot derrick, 27 Spray nozzle. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0048] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0049] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0050] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0051] The term "industrial magnesium alloy" is an abbreviation for magnesium alloy raw materials that can be produced and processed using existing magnesium alloy industrial technologies or through simple technological improvements to achieve continuous production and stable raw material supply. These materials generally feature controllable manufacturing costs, stable quality, and wide market application, serving as the most direct raw material guarantee for the industrial application of magnesium alloys. "Clean and dense preparation" refers to the process of genetic and process-based impurity control during alloy preparation to fully ensure the purity and density of the alloy, avoiding the deteriorating effects of undesigned components (impurity elements, oxides, inclusions, porosity, shrinkage cavities, etc.) on the alloy's mechanical properties and chemical stability.

[0052] To ensure that the final ingot is free from impurities from various sources, including metallic / non-metallic impurities and primary / processed oxidation inclusions, this invention provides a magnesium alloy multi-flow sequential alloying clean and dense ingot casting device, achieving a pure, uniform, and dense final ingot. The magnesium alloy multi-flow sequential alloying clean and dense ingot casting device designed in this invention avoids the slow melting / diffusion problems caused by the addition of solid intermediate alloys in the past. Instead, after the alloying elements are reasonably diluted with the magnesium-based melt to form a partially alloyed molten liquid, multiple alloying liquid streams sequentially converge into the magnesium-based melt for rapid diffusion, achieving a uniform alloying design. Figure 1 As shown in the right figure. A magnesium alloy multi-flow sequential alloying net-density casting ingot device, as shown... Figures 2-9 As shown, it includes the following devices:

[0053] Multiple slag removal chambers are used to hold different materials to be melted. Each slag removal chamber consists of a fusion unit and a slag removal unit; see reference. Figure 2 .

[0054] The fusion apparatus includes a crucible and a heating assembly. Specifically, the crucible's structure, from the outside in, consists of a steel pot body 7, a steel lifting frame 8, a thermally conductive buffer layer 9, and a high-purity, high-density graphite crucible 10. A multi-functional steel furnace cover 6 is mounted on the crucible. The multi-functional steel furnace cover 6 has a rationally arranged arrangement of one end of an alloy liquid inlet pipe 1, one end of an alloy liquid outlet pipe 3, one end of a hot gas inlet pipe 4, and one end of a vent valve 5. The alloy liquid inlet pipe 1, the alloy liquid outlet pipe 3, and the hot gas inlet pipe 4 are all covered with a heat insulation layer 2. The alloy liquid inlet pipe 1 and the alloy liquid outlet pipe 3 are all electrically heated to ensure that the pipe wall temperature is more than 50°C above the alloy melting point, thus guaranteeing good fluidity of the alloy melt. The above structure allows for a reasonable fit between the inner wall material and the outer steel material of the high-purity, high-density graphite crucible 10. The thermally conductive buffer layer 9 prevents internal stress cracking and leakage due to the difference in thermal expansion coefficients between the high-purity, high-density graphite crucible 10 and the steel pot body 7. Simultaneously, the steel lifting frame 8 facilitates crucible lifting. The alloy liquid inlet pipe 1, the alloy liquid outlet pipe 3, and the hot gas inlet pipe 4 are covered with an insulation layer, effectively mitigating temperature loss during liquid / gas conduction. The heating assembly uses a resistance wire winding 11 for heating, which is arranged around the crucible.

[0055] Impurities in magnesium alloy melts originate from various sources. To effectively and promptly remove primary oxides, process oxide inclusions, and other impurities introduced during the smelting process, this invention provides a slag removal device to ensure effective slag removal. Please refer to [link to relevant documentation]. Figure 3 and Figure 8 The slag removal device includes a slag-liquid separator 14 and a filter plate 15, wherein the filter plate 15 is connected to the alloy liquid outlet pipe 3 via a connecting rod 13, and the slag-liquid separator 14 is connected to the inlet of the alloy liquid outlet pipe 3. The crucible is provided with a slag outlet 16 at the bottom, through which the bottom slag that is finally filtered out is discharged.

[0056] The sludge-liquid separator includes an upper circular component and a lower circular component; the upper circular component and the lower circular component are fastened together.

[0057] Please see Figure 6 and Figure 7The upper circular component includes an inner circular structural support plate 14-4, an upper base plate, multiple outer diversion ribs 14-5, multiple inner diversion ribs 14-6, and a filter screen 14-7. The inner circular structural support plate 14-4 is fixedly connected to the upper base plate. The upper base plate has a liquid outlet 14-8 at its center. The upper circular component is connected to the inlet of the alloy liquid outlet pipe 3 through the liquid outlet 14-8. The multiple inner diversion ribs 14-6 and the multiple outer diversion ribs 14-5 are arranged in a ring from the inside to the outside of the upper base plate with the liquid outlet 14-8 as the center. The filter screen 14-7 is inserted between the multiple inner diversion ribs 14-6 and between the multiple outer diversion ribs 14-5.

[0058] Please see Figure 4 and Figure 5 The lower circular component includes an outer circular structural support plate 14-1, a groove plate 14-3, and a lower bottom plate; the outer circular structural support plate 14-1 is fixedly connected to the lower bottom plate, the lower bottom plate is provided with a plurality of liquid inlets 14-2, and the groove plate 14-3 is fixedly connected to the lower bottom plate;

[0059] The inner circular structural support plate 14-4 is fastened to the outer circular structural support plate 14-1;

[0060] The filter plate 15 has filter holes 15-5 evenly distributed on it, such as Figure 8 As shown in Figure A, the cross-section of the filter residue hole is trapezoidal, with the upper and lower bases of the trapezoid being the upper and lower surfaces of the filter residue hole 15-5, respectively. The lower surface of the filter residue hole 15-5 faces the bottom of the crucible. The filter residue plate 15 has several circumferentially evenly distributed connection points 15-1 that are connected to the connecting rod 13. The connecting rod 13 is fixedly connected to the connection points 15-1. The filter residue plate has a liquid inlet hole 15-4, and a rotating cover 15-2 is provided on the liquid inlet hole 15-4 for use. The rotating cover 15-2 is rotatably connected to the filter residue plate 15, and a fixed pin 15-3 can be used to connect the rotating cover 15-2 and the filter residue plate 15.

[0061] The operation method of the above-mentioned fusion device and slag removal device is as follows: First, a partial alloyed melt needs to be prepared. The multi-functional steel furnace cover 6 is opened in one of the fusion and slag removal chambers. The material to be melted is placed inside the crucible according to the designed content. Then, the multi-functional steel furnace cover 6 is closed, and the heating program is followed until the material melts. Throughout the process, the thermal protection system is continuously activated to create a thermal inert gas protective atmosphere in the chamber. After the material is completely melted to form a partial alloyed melt, the slag-liquid separator 14 and the filter plate 15 are connected together with the alloy liquid outlet pipe 3 and lowered to the bottom of the crucible. This allows the filter plate 15 to filter large-sized slag through the evenly distributed filter holes 15-5. Simultaneously, the slag-liquid separator 14 is positioned, and secondary slag filtration is achieved through the annularly distributed outer diversion ribs 14-5 and inner diversion ribs 14-6, with the filter screens 14-7 inserted in the interval areas of the same layer of diversion ribs. Similarly, the other alloying melts complete the above process in their respective fusion and slag removal chambers. Then, the alloying melts in each fusion and slag removal chamber are sequentially exported to the final alloying chamber, realizing the technical design of "sequential alloying".

[0062] Please see Figure 9 The partially alloyed melts 1, 2, ..., n are fused separately in independent fusion systems for later use. Following a designed sequence, they are sequentially drawn into the final fusion system through the slag removal device and the alloy melt outlet pipe 3 to complete sequential alloying. The final alloyed melt is then guided to a clean, dense ingot casting system for alloy ingot casting, or to other alloy melt inlets (such as continuous casting / rolling inlets or die-casting machine inlets). It should be noted that the independent fusion systems in this invention are parallel and have no positional requirements. Multiple pure partially alloyed melts are sequentially drawn into the system, and the order is adjusted according to the specific characteristics of different alloys.

[0063] Conventional inert gas protection systems use cold gas, which removes the oxidizing atmosphere by purging the near-liquid surface region of the melt to achieve a certain protective effect. However, since cold gas can disturb the near-liquid surface temperature field and affect the condensation sequence and crystallization process, this invention uses a preheating method to ensure hot protection of the inert gas.

[0064] Please see Figure 2The hot protection assembly includes a gas heater 17, a hot gas distribution device 20, and an inlet 18. The inlet 18 is located at the bottom of the gas heater 17 and is connected to the gas heater 17. The gas heater 17 is connected to the hot protection gas inlet pipe 4. The hot protection system mainly heats the gas to 600-800℃ through the gas heater 17, and then enters the crucible chamber and the hot gas distribution device 20 through the hot gas inlet pipe 4 to protect the liquid surface of the intermediate chamber 19 and the crystallizer 22 from oxidation contamination. Cold inert gas enters through the inlet 18. The hot gas distribution device 20 is a pipe, which is arranged in a ring on the intermediate chamber and is connected to the hot protection gas inlet pipe 4. The hot gas outlet of the hot gas distribution device 20 is above the liquid surface of the intermediate chamber 19.

[0065] The clean casting ingot assembly includes an intermediate chamber 19, a crystallizer 22, a cooling device 24, and an ingot guide 26. The alloy liquid outlet pipe is connected to the intermediate chamber 19, and the bottom of the intermediate chamber 19 is connected to the crystallizer 22. The cooling device 24 is installed on the crystallizer 22, and the ingot guide 26 is located at the bottom of the crystallizer 22. Specifically, the cooling device 24 includes a water-cooling pipe 21 and a spray device. The water-cooling pipe 21 is located on the inner wall of the graphite forming channel 23, and the spray device consists of spray nozzles 27 arranged circumferentially on the annular adjacent side at the lower end of the graphite forming channel 23. Figure 10 As shown;

[0066] After sequential alloying, the magnesium alloy is fed into the intermediate chamber through the alloy liquid outlet pipe 3. Under the hot protective atmosphere, the liquid flow in the alloy chamber is slowed down and flows into the crystallizer 22. The water cooling pipe 21 is coiled around the inner wall of the graphite forming channel 23 adjacent to the crystallizer 22 to achieve a controllable and adjustable cooling rate. Finally, the solidified ingot 25 is pulled out by the ingot derrick 26. During the pulling process, water cooling is sprayed through the spray nozzle 27 to achieve further rapid cooling.

[0067] Based on the above-mentioned magnesium alloy multi-flow sequential alloying clean-dense casting ingot apparatus, the present invention provides a magnesium alloy multi-flow sequential alloying clean-dense casting ingot method, comprising the following steps:

[0068] (1) Before loading, the alloy liquid inlet pipe 1 and the alloy liquid outlet pipe 3 are heated by electric heating so that the pipe wall temperature is more than 50°C higher than the alloy melting point.

[0069] Cold inert gas enters the gas heater 17 through the gas inlet 18, heating the gas to 600-800°C. The heated gas then enters the crucible through the hot gas inlet pipe, forming a hot inert gas protective atmosphere. The hot gas distribution device 20 protects the magnesium alloy melt surface in the intermediate chamber 19 and the crystallizer 22 from oxidation contamination and the low-temperature environment. It should be noted that the inert gas used in this invention is argon with a purity of 99.999% or higher. It is understood that other protective atmospheres can also be used.

[0070] (2) Multiple magnesium alloy raw materials to be melted are placed in multiple crucibles under a hot inert gas protective atmosphere to form a partially alloyed melt 12. Then, the slag separator 14, the slag filter plate 15 and the alloy liquid outlet pipe 3 are connected and lowered to the bottom of the crucible to remove slag from the partially alloyed melt, thereby obtaining multiple pure partially alloyed melts. The magnesium alloy raw materials are high-purity magnesium with a purity >99.98%, high-purity zinc with a purity >99.99%, and high-purity aluminum with a purity >99.99%. High-purity raw materials are selected to further reduce impurities.

[0071] (3) Multiple pure partial alloying melts are flowed into the alloy liquid inlet pipe 1 of the final alloying crucible through multiple alloy liquid outlet pipes 3, and then mixed in the crucible of the final alloying crucible. The slag liquid separator 14 and the slag filter plate 15 are connected to the alloy liquid outlet pipe 3 and lowered to the bottom of the crucible to remove slag from the partial alloying melt, so as to obtain the final magnesium alloy melt.

[0072] (4) The final magnesium alloy melt is transported to the intermediate chamber 19 through the alloy liquid outlet pipe 3; then it flows into the crystallizer 22, where the magnesium melt is cooled by the water cooling pipe 21. After solidification, it is pulled out by the ingot puller 26. During the pulling process, the ingot is cooled a second time by the spray nozzle 27 to obtain a high-purity magnesium alloy.

[0073] The following description, in conjunction with specific embodiments, provides further details.

[0074] In the following specific embodiments, unless otherwise specified, all raw materials can be sourced from commercially available sources.

[0075] Example 1

[0076] The main preparation process of AZ80A magnesium alloy is as follows: batching → solid raw material melting → melt filtration and impurity removal → multi-fluid fusion → casting → magnesium alloy ingot inspection → packaging and warehousing.

[0077] The AZ80A magnesium alloy raw materials used in this embodiment are high-purity magnesium with a purity >99.98%, high-purity zinc with a purity >99.99%, and high-purity aluminum with a purity >99.99%; the cold inert gas used in this embodiment is high-purity argon with a purity of 99.99%.

[0078] The raw materials are composed of the following mass fractions: 8.3% high-purity aluminum, 0.3% high-purity zinc, and the balance high-purity magnesium. Combined with the method described in this invention and using the above-mentioned apparatus, the specific steps include:

[0079] (1) Before loading, the alloy liquid inlet pipe and alloy liquid outlet pipe are heated by electric heating so that the pipe wall temperature is more than 50°C higher than the alloy melting point.

[0080] Cold inert gas enters the gas heater through the inlet, heating the gas temperature to 50°C above the alloy's initial melting temperature. In this embodiment, the gas temperature is heated to 700-800°C, and then enters the crucible through the hot gas inlet pipe to form a hot inert gas protective atmosphere. Throughout the entire test, the hot protection components remain activated to maintain a hot inert gas protective atmosphere within the chamber. The hot gas distribution device is used to protect the intermediate chamber and the liquid surface of the crystallizer from oxidation contamination.

[0081] (2) The magnesium alloy raw materials (magnesium, zinc, and aluminum) to be melted are placed in multiple crucibles under a hot inert gas protective atmosphere to form a partially alloyed melt. The melting temperature is generally 50°C higher than the melting point of the elemental metal or intermediate alloy. For example, the melting point of pure magnesium is about 650°C, so the melting temperature will be set to 700°C. The melting temperature of pure aluminum will be set to 710°C, and the melting temperature of pure zinc will be set to 470°C. The principle for setting the melting time is to ensure that the solidified metal is completely transformed into a melt. In this embodiment, the melting time is set to 60 minutes. The slag separator, filter plate, and alloy liquid outlet pipe are connected and lowered to the bottom of the crucible to remove slag from the partially alloyed melt, resulting in a relatively pure magnesium alloy melt. Under the premise of ensuring safety and slag removal efficiency, the descent speed should not be too fast to avoid melt splashing.

[0082] (3) The magnesium alloy melt after multi-flow fusion is sequentially transported to the intermediate chamber through the alloy melt outlet pipe. The melt first undergoes secondary slag removal through filter screens inserted in the interval areas of the same-layer diversion ribs, and then flows into the crystallizer. The crystallizer is a cylindrical barrel structure without a lid or bottom, such as... Figure 10 As shown, its inner diameter is 86 mm. The magnesium alloy melt is cooled by the cooling device and solidified. After solidification, it is pulled out by the ingot puller. The part of the magnesium alloy ingot pulled out of the crystallizer will be further cooled by the spray device set at the bottom.

[0083] Comparative Example 1

[0084] The main preparation process of low-purity AZ80A magnesium alloy is as follows: batching → alloying → refining and slag removal → single-liquid flow mixing and casting → ingot inspection → packaging and warehousing.

[0085] Step 1: Ingredients

[0086] High-purity magnesium (>99.98%), high-purity zinc (>99.99%), and high-purity aluminum (>99.99%) are used. The materials are proportioned according to the mass fraction of the target alloy, with high-purity aluminum at 8.3 wt.%, high-purity zinc at 0.3 wt.%, and high-purity magnesium as the balance.

[0087] Step 2, Alloying

[0088] In the same crucible, pure magnesium (99.98%) raw material was heated until completely melted, and then pure aluminum (99.99%) and 3N pure zinc (99.99%) raw materials were added sequentially to the magnesium melt. Unlike the previous example, here alloying was performed first, followed by refining and slag removal.

[0089] Step 3: Refining and Slag Removal

[0090] A refining agent is added to the molten mixed metal. The total amount of refining agent needs to be calculated in advance according to the production plan, and is 2.5% of the total weight of the alloy being smelted. After the refining agent reacts with the melt for about 40 minutes, slag removal can be performed. Slag removal removes the black refining slag from the bottom of the crucible, achieving the effect of removing impurities from the melt. The refining agent is flux No. 2. Flux No. 2 can be obtained through commercial channels, and this invention does not impose any special restrictions. The flux No. 2 used in this invention was purchased from Taihang Technology Co., Ltd. in Hebi City.

[0091] Step 4: Casting

[0092] After multiple refining and slag removal processes, the magnesium alloy melt is ready for single-flow mixing and casting. The refined magnesium alloy melt is transferred to a crystallizer via pouring or a transfer pipe, where it is cooled by the cooling device. After solidification, it is pulled out by an ingot puller and cooled again by the cooling device. Typically, the refining process is repeated 1-2 times until the target design composition is achieved.

[0093] Table 1. Comparison of chemical composition (wt.%) of as-cast AZ80A with different purities

[0094] Lowpurity (LP) 8.35 0.30 0.32 0.0046 0.0150 <0.0010 <0.0010 Highpurity (HP) 8.34 0.23 0.34 0.0038 0.0030 <0.0010 <0.0010

[0095] Based on the multi-fluid flow sequential alloying clean-dense ingot system, the composition and impurity content of as-cast AZ80A with different purities were prepared as shown in Table 1. It can be seen that by selecting higher purity raw materials (primary magnesium purity >99.98%, primary aluminum purity >99.99%, pure zinc purity >99.99%) and cleaner vessel wall materials (high-purity high-density graphite), the contents of key impurities Fe and Si were significantly reduced. Specifically, the Si impurity content decreased from 150 ppm to 30 ppm, and the Fe impurity content decreased from 46 ppm to 38 ppm.

[0096] The most direct and beneficial effect of reducing Fe and Si impurity content is a significant improvement in the corrosion resistance of the alloy. Hydrogen evolution and weight loss corrosion properties of two magnesium alloys were compared. The test environment was a 3.5% NaCl solution, maintained at a constant temperature of 25℃, for 168 hours. The test results are as follows: Figure 11 As shown, Figure 11 The corrosion rates of the above-mentioned as-cast AZ80A alloys with different purities were compared. Figure 11 As shown in Figure a, the low-purity as-cast AZ80A alloy exhibits not only a higher hydrogen evolution rate compared to the high-purity group, but also a significantly greater fluctuation in hydrogen evolution rate. For example, during the 168-hour immersion test, the lowest hydrogen evolution rate in the low-purity group was approximately 4 ml / cm³. 2 The hydrogen evolution rate can reach as high as 16 ml / cm³. 2 The range is approximately 12 ml / cm. 2 After effectively reducing the Fe and Si impurity content through a multi-fluid flow sequential alloying and dense casting ingot system, the hydrogen evolution rate of the high-purity group was below 3 ml / cm³ after 168 hours of immersion testing. 2 Furthermore, the volatility was significantly reduced, and the range decreased to approximately 1 ml / cm. 2 The corrosion rate calculated based on hydrogen evolution data and weight loss data is as follows: Figure 11 As shown in Figure b, the corrosion rate (calculated from hydrogen evolution data) decreased from 2.8±1.8 mm / a in the low purity group to 0.7±0.1 mm / a in the high purity group. The corrosion resistance was improved, and the fluctuation was significantly narrowed, demonstrating the excellent and stable performance characteristics of high-quality magnesium alloys.

[0097] The low-purity group exhibited larger and more numerous corrosion pits, while the high-purity group showed fewer surface corrosion pits with significantly smaller individual pits, consistent with the differences in corrosion rates among the different purity groups. These results demonstrate that a high-purity magnesium alloy can be prepared using a multi-fluid flow sequential alloying ingot casting system, achieving the high-quality magnesium alloy properties of excellent and stable corrosion resistance.

[0098] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0099] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A magnesium alloy multi-flow sequential alloying and dense casting ingot device, comprising a furnace body, characterized in that, Also includes: Multiple fusion components, each including a crucible and a heating component, wherein the top of the crucible is connected to one end of an alloy liquid inlet pipe (1), one end of a hot protective gas inlet pipe (4), one end of an alloy liquid outlet pipe (3), and one end of a vent valve (5); the bottom of the crucible is provided with a slag outlet (16); and the heating component is provided on the outside of the crucible. A slag removal assembly is located at the bottom of the crucible. The slag removal assembly includes a slag-liquid separator (14) and a slag filter plate (15). The slag-liquid separator (14) is connected to one end of the alloy liquid outlet pipe (3). The slag filter plate (15) is connected to the side wall of the alloy liquid outlet pipe (3). The hot protection component includes a gas heater (17), a hot gas distribution device (20), and an air inlet (18); the air inlet (18) is located at the bottom of the gas heater (17) and is connected to the gas heater (17); the gas heater (17) is connected to the other end of the hot protection gas inlet pipe (4); the hot gas distribution device is connected to the hot protection gas inlet pipe (4); The clean casting ingot assembly includes an intermediate chamber (19), a crystallizer (22), a cooling device, and an ingot maker (26). The other end of the alloy liquid outlet pipe (3) is connected to the intermediate chamber (19). The hot gas distribution device (20) is arranged around the intermediate chamber (19). The bottom of the intermediate chamber (19) is connected to the crystallizer (22). The crystallizer (22) is equipped with a cooling device. The ingot maker (26) is located at the bottom of the crystallizer (22).

2. The magnesium alloy multi-flow sequential alloying net-density casting ingot device according to claim 1, characterized in that, The sludge-liquid separator (14) includes an upper circular component and a lower circular component; The upper circular component includes an inner circular structural support plate (14-4), an upper base plate, multiple outer diversion ribs (14-5), multiple inner diversion ribs (14-6), and a filter screen (14-7). The inner circular structural support plate (14-4) is fixedly connected to the upper base plate. The upper base plate has a liquid outlet (14-8) at its center. The upper circular component is connected to one end of the alloy liquid outlet pipe (3) through the liquid outlet (14-8). Multiple inner diversion ribs (14-6) and multiple outer diversion ribs (14-5) are arranged in a ring from the inside to the outside of the upper base plate with the liquid outlet (14-8) as the center. The filter screen (14-7) is inserted between the multiple inner diversion ribs (14-6) and between the multiple outer diversion ribs (14-5). The lower circular component includes an outer circular structural support plate (14-1), a groove plate (14-3), and a lower base plate; the outer circular structural support plate (14-1) is fixedly connected to the lower base plate, the lower base plate is provided with multiple liquid inlets (14-2), and the groove plate (14-3) is fixedly connected to the lower base plate; The inner circular structural support plate (14-4) is fastened to the outer circular structural support plate (14-1).

3. The magnesium alloy multi-fluid flow sequential alloying net-density casting ingot device according to claim 1, characterized in that, The filter plate (15) is connected to the side wall of the alloy liquid outlet pipe (3) via a connecting rod (13); the filter plate (15) is provided with a filter hole (15-5), a liquid inlet hole (15-4) and a rotating cover (15-2), the rotating cover (15-2) is rotatably connected to the filter plate (15), and the rotation of the rotating cover (15-2) realizes the sealing and opening of the liquid inlet hole (15-4).

4. The magnesium alloy multi-fluid flow sequential alloying net-density casting ingot device according to claim 1, characterized in that, The crystallizer (22) is provided with a graphite forming channel (23); The cooling device includes a water-cooled pipe (21) and a spray device (24). The water-cooled pipe (21) is located on the inner wall of the graphite forming channel (23), and the spray device (24) is located on the annular side of the lower end of the graphite forming channel (23) of the crystallizer (22).

5. The magnesium alloy multi-flow sequential alloying net-density casting ingot device according to claim 1, characterized in that, The crucible includes a crucible body and a steel furnace cover (6). The crucible body, from the outside to the inside, includes a steel pot body (7), a steel hoisting frame (8), a heat-conducting buffer pad (9), and a high-purity, high-density graphite crucible (10) chamber.

6. The magnesium alloy multi-flow sequential alloying net-density casting ingot device according to claim 1, characterized in that, The alloy liquid inlet pipe (1), the alloy liquid outlet pipe (3), and the hot protective gas inlet pipe (4) are all provided with a heat insulation layer (2).

7. A method for sequential alloying and net-density casting of magnesium alloy ingots using multi-fluid flow, characterized in that, The net-density casting ingot apparatus according to any one of claims 1-6 includes the following steps: Before loading, the alloy liquid inlet pipe (1) and alloy liquid outlet pipe (3) are heated by electric heating so that the pipe wall temperature is more than 50°C higher than the alloy melting point. Cold inert gas enters the gas heater (17) through the gas inlet (18) and heats the gas temperature to 600-800℃. It then enters the crucible through the hot gas inlet pipe (4) to form a hot inert gas protective atmosphere. The hot gas distribution device (20) is used to protect the magnesium alloy melt surface in the intermediate chamber (19) and the crystallizer (22) from oxidation pollution and low temperature environment. Multiple magnesium alloy raw materials to be melted are placed in multiple crucibles and smelted in a hot inert gas protective atmosphere to form a partially alloyed melt. Then, the slag separator (14), the slag filter plate (15) and the alloy liquid outlet pipe (3) are connected and lowered to the bottom of the crucible to remove slag from the partially alloyed melt, so as to obtain multiple pure partially alloyed melts. Multiple pure partially alloyed melts are fed into the alloy liquid inlet pipe (1) of the final alloying crucible through multiple alloy liquid outlet pipes (3), and then mixed in the crucible. The slag liquid separator (14) and the slag filter plate (15) are connected to the alloy liquid outlet pipe (3) and lowered to the bottom of the crucible to remove slag from the partially alloyed melts, thus obtaining the final magnesium alloy melt. Finally, the magnesium alloy melt is transported to the intermediate chamber (19) through the alloy liquid outlet pipe (3); then it flows into the crystallizer (22), is cooled under the action of the cooling device, and after solidification, it is pulled out by the ingot puller (26). The ingot is cooled a second time during the pulling process.

8. The method for sequential alloying and net-density casting of magnesium alloys according to claim 7, characterized in that, The magnesium alloy raw materials are high-purity magnesium with a purity of >99.98%, high-purity zinc with a purity of >99.99%, and high-purity aluminum with a purity of >99.99%.

9. The method for sequential alloying and net-density casting of magnesium alloy multi-fluid flow ingots according to claim 7, characterized in that, The inert gas is argon with a purity of 99.999% or higher.

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