Semi-continuous casting device for large-size highly-alloyed magnesium-rare earth alloy round ingot

Abstract

The invention belongs to the technical field of semi-continuous casting devices, and relates to a large-size highly-alloyed magnesium-rare earth alloy round ingot semi-continuous casting device which comprises a crystallizer, a dummy ingot base and a flow dividing disc, a plurality of stages of arc bosses are arranged on the inner bottom face of the dummy ingot base, and the radiuses of the arc bosses are sequentially increased from top to bottom; the core part is used for promoting high-temperature melt to quickly flow to the edge part and reducing the temperature difference between the core part and the edge part; the flow dividing disc comprises a vertical pipe and a plurality of fan-shaped flow dividing areas, the flow dividing areas are arranged in the circumferential direction of the vertical pipe, and the high-temperature melt flows in from the vertical pipe, flows out of the flow dividing areas and enters the crystallizer, so that the radial flow of the high-temperature melt is more uniform. According to the invention, the uniformity of melt flow, the uniformity of temperature and the uniformity of solute and structure of the cast ingot are obviously improved, the hot cracking tendency is reduced, and the cracking problem in the casting process is reduced. The prepared large-size high-toughness magnesium alloy cast ingot is free of cracks, segregation, slag inclusion and other defects of the structure, and the percent of pass is larger than 98%.

Description

Technical Field

[0001] The invention belongs to the technical field of semi-continuous casting devices and relates to a semi-continuous casting device for large-size high-alloyed magnesium rare earth alloy round ingots. Background Art

[0002] With the rapid development of aerospace, rail transit and other fields, the industry has an increasing demand for lightweight engineering materials, and the demand for larger and higher quality magnesium alloy components is increasing day by day. The precursor of large-sized magnesium alloy forgings requires high-quality large-sized ingots, but the high content of rare earth elements in high-strength and tough magnesium alloys leads to more quality problems, which greatly limits the application of magnesium alloys. Among the many quality problems, two are particularly serious. One is segregation. As a defect that runs through the casting process, segregation is difficult to eliminate by heat treatment. This type of defect is more serious in large-sized ingots with high rare earth content. It will reduce the performance of the ingot and make the subsequent deformation process more difficult to implement. The second is casting cracking. Highly alloyed ingots, especially large-sized ingots, have a greater tendency to produce hot cracking and cold cracking during the casting process, which greatly affects the yield of the ingot.

[0003] In semi-continuous casting production, mechanical stirring, electromagnetic stirring and other methods are often used to effectively improve the uniformity of melt flow inside the crystallizer. However, such methods are less effective in the production of large-scale high-strength and tough magnesium alloy ingots. First, the chemical properties of magnesium alloys are more active. Even under a protective atmosphere, slight fluctuations in the melt may cause melt combustion, which is accompanied by great production safety issues. Second, electromagnetic stirring forms an induced current inside the melt through alternating current, and achieves the effect of stirring through the Lorentz force. However, due to the skin effect, electromagnetic stirring has limited stirring effect on the core position of large-scale ingots.

[0004] In view of the characteristics of magnesium alloy production, passive diversion is currently a more reasonable method, but the effect of passive diversion depends largely on the structural rationality of the diversion device and the mutual matching with the process parameters. Especially when producing large-scale high-alloyed magnesium rare earth alloy ingots, it is particularly easy to crack. Therefore, it is necessary to develop a new passive diversion device for large-scale high-strength and tough magnesium alloy ingots to improve the uniformity of melt flow inside the crystallizer, reduce casting segregation, and avoid casting cracking. Summary of the invention

[0005] In order to solve the problems of ingot cracking and poor surface quality of billets in the production process of existing large-scale high-strength and tough magnesium alloy ingots, the present invention provides a large-scale high-alloyed magnesium rare earth alloy ingot semi-continuous casting device, which can effectively improve the uniformity of melt flow inside the crystallizer during the casting process, reduce the temperature gradient between the core and the surface of the ingot, make the liquid cavity morphology more gentle, significantly improve the segregation problem, and significantly reduce the cracking of the ingot. The magnesium alloy billet produced by the device has good surface quality and uniform internal structure. After subsequent normal processing, the corresponding products can be widely used in military fields such as aviation and aerospace, and the product stability is further improved.

[0006] The technical solution of the present invention is as follows:

[0007] The semi-continuous casting device of a large-scale high-alloyed magnesium rare earth alloy round ingot of the present invention comprises a columnar crystallizer, an ingot starter base which can be sleeved with the crystallizer, and a diverter plate arranged above the crystallizer for guiding the melt, wherein the ingot starter base can move relative to the crystallizer, wherein:

[0008] A multi-stage arc boss with a radius increasing from top to bottom is provided on the inner bottom surface of the ingot base, which is used to promote the high-temperature melt to flow to the edge of the molten pool faster and reduce the temperature difference between the center of the molten pool and the edge of the molten pool; the diverter plate includes a vertical pipe and a plurality of fan-shaped diverter areas, and the diverter areas are arranged along the circumference of the vertical pipe. The high-temperature melt flows from the vertical pipe, flows out through the diverter area, and enters the crystallizer, so that the radial flow of the high-temperature melt is more uniform.

[0009] In one embodiment of the present invention, it is preferred that the multi-stage arc boss is a double-stage arc boss, including a primary arc boss connected to the bottom surface of the ingot base, and a secondary arc boss on the primary arc boss. The primary arc boss and the bottom surface of the ingot base are smoothly transitioned, and the primary arc boss and the secondary arc boss are also smoothly transitioned. Among them, it is further preferred that the radius of the primary arc boss is 400-600mm, the radius of the secondary arc boss is 100-150mm, and the heights of the primary arc boss and the secondary arc boss are both 10-20mm.

[0010] In one embodiment of the present invention, preferably, the crystallizer includes a crystallizer inner sleeve and a crystallizer outer sleeve, a platform edge is provided along the circumference of the crystallizer inner sleeve, a ring-shaped platform is provided on the top of the crystallizer outer sleeve and is embedded in the platform edge, the ring-shaped platform is located below the platform edge, and the crystallizer outer sleeve is also provided with a shell connected to the ring-shaped platform for embedding the crystallizer inner sleeve.

[0011] In one embodiment of the present invention, preferably, an annular cooling water trough is provided between the crystallizer shell and the crystallizer inner sleeve, and a water inlet pipe is provided on the crystallizer shell, and the water inlet pipe is connected to the cooling water trough.

[0012] In one embodiment of the present invention, preferably, the water inlet pipe is arranged on both sides of the crystallizer shell.

[0013] In one embodiment of the present invention, preferably, secondary cooling water outlet holes are provided along the lower side of the inner sleeve of the crystallizer, and the water outlet holes are inclined to correspond to the moving direction of the ingot during semi-continuous casting.

[0014] In one embodiment of the present invention, preferably, the shape of the inner sleeve of the crystallizer is a trumpet shape that is wide at the top and narrow at the bottom, and the inclination angle is 1-6°.

[0015] In one embodiment of the present invention, preferably, an oil inlet pipeline is provided between the platform edge and the annular platform, an oil groove is provided along the circumference of the annular platform, and an oil lubrication spray hole communicating with the oil groove is provided on the platform edge.

[0016] In one embodiment of the present invention, preferably, the oil inlet pipeline is arranged on both sides of the inner sleeve of the crystallizer.

[0017] In one embodiment of the present invention, preferably, the number of the diversion areas is six, and further preferably, the six diversion areas are evenly distributed in the circumferential direction of the vertical pipe.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The semi-continuous casting device of a large-scale high-alloyed magnesium rare earth alloy ingot of the present invention realizes the melt diversion in the casting process by relying on the diverter plate above the crystallizer, which causes less oxidation combustion than other active diversion methods. At the same time, compared with the traditional diverter plate and the ingot base, the diversion effect is better. After the diverter plate with a six-way diverter tube and the ingot base with a double boss are adopted in the present invention, the uniformity of the flow of the magnesium alloy melt in the crystallizer during the casting process is significantly improved, the uniformity of the melt temperature is improved, the uniformity of the solute and structure of the ingot is effectively improved, and the tendency of thermal cracking is reduced, and the cracking problem during the casting process is reduced. The large-scale high-strength and tough magnesium alloy ingot prepared by the method of the present invention has no cracks, and the ingot structure has no defects such as segregation and slag inclusion, and the ingot qualification rate is greater than 98%.

[0020] The high-performance magnesium alloy blank produced by the present invention has better internal quality and flaw detection pass rate than existing magnesium alloy products after various subsequent plastic forming processes, and the corresponding products can be widely used in aviation, aerospace and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a front view of a large-scale high-alloyed magnesium rare earth alloy ingot semi-continuous casting device in operation according to an embodiment of the present invention;

[0022] Figure 2 It is a front view of a semi-continuous casting device for large-scale high-alloyed magnesium rare earth alloy ingots according to an embodiment of the present invention;

[0023] Figure 3 This is a front view of the ingot base 2 of the embodiment of the present invention;

[0024] Figure 4 A top view of the diverter plate 3 according to an embodiment of the present invention;

[0025] Figure 5 It is a front view of the ingot base of the conventional semi-continuous casting device;

[0026] Figure 6 It is a schematic diagram of the structure of a diverter plate of a conventional semi-continuous casting device;

[0027] Figure 7 The distribution diagram of Gd content in the ingots cast by the semi-continuous casting device of the present invention and the conventional semi-continuous casting device along the diameter direction;

[0028] Figure 8 This is a schematic diagram of an ingot produced by a semi-continuous casting device for a large-sized high-alloyed magnesium rare earth alloy ingot according to an embodiment of the present invention.

[0029] Markings in the figure: 1-crystallizer, 11-crystallizer inner sleeve, 111-platform edge, 112-water outlet, 113-oil lubrication spray hole, 12-crystallizer shell, 121 annular platform, 122-shell, 123-water inlet pipe, 124-oil tank, 2-ingot base, 21-multi-stage arc boss, 211-first-stage arc boss, 212-second-stage arc boss, 3-diverter plate, 31-vertical pipe, 32-diverter area, 4-cooling water tank, 5-oil inlet pipe. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited to the specific implementation disclosed below.

[0032] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0033] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or a welding connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In addition, in the present invention, descriptions such as "primary", "secondary", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "primary" or "secondary" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0035] like Figures 1 to 4 As shown, a semi-continuous casting device for a large-scale high-alloyed magnesium rare earth alloy ingot according to an embodiment of the present invention has a diameter of ≥500 mm. The device comprises a cylindrical crystallizer 1, an ingot starter base 2 which can be sleeved with the crystallizer 1, and a diverter plate 3 for guiding the melt arranged above the crystallizer 1. The ingot starter base 2 can move relative to the crystallizer 1, wherein:

[0036] A multi-stage arc boss 21 with a radius increasing from top to bottom is provided on the inner bottom surface of the ingot base 2, which is used to promote the high-temperature melt to flow to the edge of the molten pool faster and reduce the temperature difference between the center of the molten pool and the edge of the molten pool; the diverter plate 3 includes a vertical pipe 31 and a plurality of fan-shaped diverter areas 32, and the diverter areas 32 are arranged along the circumference of the vertical pipe 31. The high-temperature melt flows from the vertical pipe 31, flows out through the diverter area 32, and enters the crystallizer 1, so that the radial flow of the high-temperature melt is more uniform.

[0037] When in use, first install the crystallizer 1 on the semi-continuous casting platform, seal the ingot base 2 and the crystallizer 1 with asbestos rope, and connect cooling water with a cooling water flow rate of 100-200L / min. Lubricating oil seeps out from the oil outlet 5 above the crystallizer. After the water flow is stable and the equipment is baked, the magnesium alloy melt flows out from the furnace guide pipe and is introduced into the crystallizer through the diverter plate 3. Casting begins after the melt level rises 80-100mm and covers the diverter plate 3. The casting speed is set to 25-35mm / min. An ingot, a metal liquid-solid two-phase zone, a metal melt and a metal melt level are formed in sequence above the ingot base 2 until the casting is completed. The entire casting process is carried out under a protective atmosphere of nitrogen and sulfur hexafluoride.

[0038] The present invention sets a multi-stage arc boss 21 on the inner bottom surface of the ingot base 2. When the high-temperature melt falls into the molten pool, due to the height difference of the bottom surface, the high-temperature melt can flow to the edge of the molten pool faster, reducing the temperature difference between the core and the edge of the molten pool, which can effectively improve the uniformity of the melt temperature in the bottoming stage, reduce the stress at the bottom of the ingot, reduce the generation of cracks at the bottom of the ingot, and significantly reduce the cracks in the product; and, a plurality of diversion areas 32 are set along the circumference of the diversion plate 3, the high-temperature melt diversion stroke is short, and the radial flow distribution is more uniform. Therefore, the present invention can effectively improve the macro segregation of the ingot and reduce quality problems such as ingot cracking through the synergistic effect of the four-way diversion area 32 and the ingot base with the multi-stage arc boss 21.

[0039] In another embodiment of the present invention, the diverter plate 3 can be made of stainless steel, wherein the vertical pipe 31 is threadedly connected to the furnace guide pipe (not marked in the figure), and the high-temperature melt flows out of the furnace and flows into the vertical pipe 31 through the furnace guide pipe. At the same time, in order to prevent the melt from seeping out during the casting process, talcum powder and water glass are used to seal the threaded connection. In addition, in order to improve the connection strength between the vertical pipe 31 and the diverter area 32, a number of reinforcing ribs (not marked in the figure) are also provided between the vertical pipe 31 and the diverter plate 3, such as steel wires and other connecting reinforcements.

[0040] The flow dividing area 32 is a fan-shaped square tube, whose inner diameter is the same as the diameter of the vertical tube 31, which is 30-40 mm, and whose outer diameter is the same as the diameter of the flow dividing plate 3. The diameter of the flow dividing plate 3 can be 60-90 mm.

[0041] The multi-stage arc boss 21 is preferably a double-stage arc boss, and the double-stage arc boss 21 includes a primary arc boss 211 connected to the bottom surface of the ingot starter base 2, and a secondary arc boss 212 on the primary arc boss 211. It can be further preferably configured that the primary arc boss 211 smoothly transitions to the secondary arc boss 212, and the primary arc boss 211 also smoothly transitions to the bottom surface of the ingot starter base 2.

[0042] Among them, the parameter settings of the first-level arc boss 211 and the second-level arc boss 212 can be as follows, and the present invention does not impose any restrictions thereto, and the specific settings can be made according to actual working conditions: the radius of the first-level arc boss 211 is 400-600mm, the radius of the second-level arc boss 212 is 100-150mm, and the heights of the first-level arc boss 211 and the second-level arc boss 212 are both 10-20mm.

[0043] In another embodiment of the present invention, the crystallizer 1 includes a crystallizer inner sleeve 11 and a crystallizer outer sleeve 12, a platform edge 111 is provided along the circumference of the crystallizer inner sleeve 11, and a ring-shaped platform 121 is provided on the top of the crystallizer outer sleeve 12 to fit in with the platform edge 111, the ring-shaped platform 121 is located below the platform edge 111, and the crystallizer outer sleeve 12 is further provided with an outer shell 122 connected to the ring-shaped platform 121 for embedding the crystallizer inner sleeve 11. The ring-shaped platform 121 and the outer shell 122 are designed to be integrally formed.

[0044] In another embodiment of the present invention, an annular cooling water trough 4 is provided between the crystallizer shell 12 and the crystallizer inner sleeve 11, and a water inlet pipe 123 is provided on the crystallizer shell. The water inlet pipe 123 is connected to the cooling water trough 4 for cooling the ingot.

[0045] Optionally, the water inlet pipe 123 is arranged on both sides of the crystallizer shell 12.

[0046] In another embodiment of the present invention, a secondary cooling water outlet 112 is provided along the lower side of the inner sleeve 11 of the crystallizer, and the water outlet 112 is arranged obliquely, corresponding to the moving direction of the ingot during semi-continuous casting, so as to perform secondary cooling on the ingot and improve the cooling rate of the ingot. In this embodiment, the primary cooling and secondary cooling of the ingot can be achieved by providing the cooling water tank 4 and the water outlet 112.

[0047] In another embodiment of the present invention, preferably, the shape of the inner sleeve 11 of the crystallizer is a trumpet shape that is wide at the top and narrow at the bottom, and the inclination angle is 1-6°, so as to avoid that during the casting process, due to the cooling and shrinkage of the ingot, the ingot and the crystallizer cannot effectively contact each other, the cooling intensity is reduced, and the initial solidification shell on the surface of the ingot is remelted, causing serious segregation, thereby reducing the surface quality of the ingot.

[0048] In order to facilitate installation and avoid stress concentration, in the embodiment of the present invention, the diameter of the upper end of the dummy ingot base 2 is 30-50 mm larger than the diameter of the bottom, and an angled step is used in the middle. The dummy ingot base 2 can be made of stainless steel.

[0049] As for the material of the inner sleeve 11 of the crystallizer, copper can be selected and the inner wall thickness is designed to be 10-15 mm.

[0050] In another embodiment of the present invention, an oil inlet pipe 5 is provided between the platform edge 111 and the annular platform 121, and an oil groove 124 is provided along the circumference of the annular platform 121, and an oil lubrication spray hole 113 communicating with the oil groove 124 is provided on the platform edge 111, and a plurality of oil lubrication spray holes 113 are provided at intervals around the platform edge 111 in the circumferential direction, and the specific number is set according to the working conditions. The lubricating oil can be transported to the inside of the crystallizer through the oil inlet pipe 5 and the oil lubrication spray holes 113, and an oil film is formed on the surface of the crystallizer, which can significantly reduce surface defects such as cold shut and pull marks, and improve the surface quality of the ingot.

[0051] Optionally, the oil inlet pipeline 5 is arranged on both sides of the crystallizer inner sleeve 11.

[0052] In another embodiment of the present invention, the number of the diversion areas 32 is six, and further, the six diversion areas 32 may be evenly distributed in the circumferential direction of the vertical pipe 31 .

[0053] The present invention first installs the crystallizer 1 on the semi-continuous casting platform, uses the ingot base 2 and the asbestos rope to seal the bottom of the crystallizer inner sleeve 11, passes cooling water into the cooling water tank 4, turns on the oil pump, the oil tank 124 is below the crystallizer inner sleeve 11, and the crystallizer inner sleeve 11 is provided with an oil lubrication spray hole 113. The cooling water tank 4 is in the gap between the crystallizer shell 12 and the inner sleeve 11. The assembly gap between the oil tank 3 and the water tank 6 is sealed by a rubber ring. Finally, the cooling water is sprayed from the cooling water hole 112 below the crystallizer, and the water flow rate is 120L. / min, lubricating oil seeps out from the oil lubrication spray hole 113 on the inner sleeve 11 of the crystallizer, and after the water flow is stable and the equipment is baked; the magnesium alloy melt is introduced into the inner sleeve 11 of the crystallizer from the guide pipe through the diverter plate 3, and casting begins after the melt level rises by 80-100mm. The casting speed is set to 25-35mm / min, and an ingot, a metal liquid-solid two-phase region, a metal melt and a metal melt level are formed in sequence above the ingot guide base 2 until the casting is completed. The whole process needs to be carried out under the protective atmosphere of nitrogen and sulfur hexafluoride.

[0054] Example

[0055] The following is a detailed description of a large-scale high-alloy magnesium rare earth alloy round ingot semi-continuous casting device of the present invention, taking a large-scale φ510mm Mg-10Gd-3Y-3Zn-0.5Zr magnesium rare earth alloy semi-continuous casting ingot as an example:

[0056] (1) Casting preparation stage:

[0057] like Figures 2-3As shown, the ingot base 2 is raised, sleeved on the inner sleeve 11 of the crystallizer, and sealed with an asbestos rope. After the sealing is completed, the inner sleeve 11 of the crystallizer is baked.

[0058] like Figure 1 and Figure 4 As shown, the vertical pipe 31 of the diverter plate 3 is threadedly connected to the furnace guide pipe (not marked in the figure), and the threaded connection is sealed with talcum powder and water glass and baked.

[0059] Turn on the water pump and wait until the water pressure stabilizes at 3-4kg / cm 2 Finally, the preparation work is completed when the melt temperature reaches 695-705℃.

[0060] (2) Casting start stage:

[0061] The furnace control valve is opened, and the melt in the furnace flows through the furnace guide pipe under the action of static pressure, passes through the diverter plate 3, and flows into the crystallizer after diversion.

[0062] When the melt level in the crystallizer reaches the bottom of the diverter plate 3, casting begins, the water flow rate is adjusted to 160-200L / min, and the casting speed is controlled at 35-40mm / min. During this period, the scum on the surface of the melt in the crystallizer needs to be cleaned in time to prevent the internal slag from being the source of cracks and causing the ingot to crack. After contacting the crystallizer, the melt quickly forms a solidified shell and begins to move downward with the ingot base 2 under the action of gravity.

[0063] (3) Casting stabilization stage: After the casting process stabilizes, the liquid level is gradually controlled to be 20-30 mm above the diverter plate. The ingot with a solidified crust formed on the surface is rapidly cooled after passing through the cooling water area.

[0064] (4) Casting end stage:

[0065] When the ingot length reaches the required length, the furnace control valve is closed, and casting is stopped when no more melt flows into the crystallizer. The casting is completed when the ingot slowly cools and moves until it is separated from the crystallizer.

[0066] Comparative Example

[0067] The comparative example also takes a large-size Mg-10Gd-3Y-3Zn-0.5Zr magnesium rare earth alloy semi-continuous ingot of φ510mm as an example. The structure and preparation method of the ingot casting device used in the comparative example are the same as those of Example 1. The difference is that 1) using Figure 5 The ingot base shown is a conventional ingot base without a boss; 2) the ingot base used is Figure 6 Conventional manifold shown.

[0068] Compared with the embodiments, 1) in the conventional ingot guide base without a boss, during the discharge process, the high-temperature melt in the middle can only flow slowly to the edge of the base, which increases the temperature difference at the bottom of the ingot during the discharge and bottoming stage. The obtained product is prone to cracks, and it is difficult to obtain a large-sized magnesium alloy ingot with good quality. The improved ingot guide base of the present invention can make the high-temperature melt flow to the edge faster, reduce the temperature difference between the center and the edge, and thus reduce the phenomenon of cracks. 2) During the casting process of the conventional diverter plate, the radial melt flow rate of the diverter plate is difficult to control, there is obvious temperature unevenness, and the diversion effect is poor. During the casting process, the improved diverter plate of the present invention has a short diversion stroke and a more uniform radial flow distribution, which effectively improves the macro segregation of the ingot and reduces quality problems such as ingot cracking.

[0069] After casting a large-size Mg-10Gd-3Y-3Zn-0.5Zr magnesium rare earth alloy ingot of φ510 mm using the embodiment and the comparative example, the content of the main alloy element Gd along the ingot diameter direction was tested using a direct reading spectrometer. The results are as follows: Figure 7 As shown, it can be found that the segregation degree of the ingot produced by the conventional device is more serious than that of the ingot obtained by the device of the present invention.

[0070] Figure 8 The Mg-10Gd-3Y-3Zn-0.5Zr magnesium rare earth alloy round ingot with a diameter of 510 mm produced by the device of the present invention has a smooth surface and is free of defects such as cracks.

[0071] The present invention makes the melt flow inside the crystallizer more uniform by installing a diverter plate with a six-way diverter tube and an ingot guide base with a double-stage boss under the guide tube. During the casting process, the flow mode of the melt has an important influence on the temperature field distribution inside the liquid cavity, thermal cracking, and macro-segregation. When the diverter plate is not added, the melt will form two vortices at the solidification front and the edge of the molten pool under the action of thermal buoyancy and momentum convection. The main flow velocity of the melt is at the solidification front and the upper part of the molten pool, and the distribution is uneven. After adding the traditional diverter plate, due to the action of the diverter plate, the melt generates a strong vortex in the molten pool, and reduces the vertical downward flow velocity of the melt in the center of the molten pool. The melt flow rate distribution is more uniform, and the temperature gradient of the ingot core and surface is reduced to a certain extent. However, when the melt flows through the traditional diverter plate, it is difficult to control the uniformity of the melt flow in the radial direction of the diverter plate. There is still a certain temperature difference in the radial direction of the molten pool, which leads to an increase in stress and then cracks. Compared with the traditional diverter plate, the diverter plate with six-way diverter tubes in the present invention diverts the melt to six diverter tubes when it flows downward and reaches the center of the diverter plate, which significantly shortens the diversion distance of the melt and reduces the unevenness of the melt flow in the radial direction of the diverter plate. It can effectively improve the macro-segregation of the ingot and reduce quality problems such as ingot cracking.

[0072] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A semi-continuous casting device for large-scale high-alloyed magnesium rare earth alloy ingots, characterized in that: It comprises a columnar crystallizer, a starter base which can be sleeved with the crystallizer, and a diverter plate arranged above the crystallizer for guiding the melt, wherein the starter base can move relative to the crystallizer, wherein: A multi-stage arc boss with a radius increasing from top to bottom is provided on the inner bottom surface of the ingot base, which is used to promote the high-temperature melt to flow to the edge of the molten pool faster and reduce the temperature difference between the center of the molten pool and the edge of the molten pool; the diverter plate includes a vertical pipe and a plurality of fan-shaped diverter areas, and the diverter areas are arranged along the circumference of the vertical pipe. The high-temperature melt flows from the vertical pipe, flows out through the diverter area, and enters the crystallizer, so that the radial flow of the high-temperature melt is more uniform.

2. The semi-continuous casting device for large-scale high-alloyed magnesium rare earth alloy ingots according to claim 1 is characterized in that: The multi-stage circular arc boss is a double-stage circular arc boss, comprising a primary circular arc boss connected to the bottom surface of the ingot base, and a secondary circular arc boss on the primary circular arc boss.

3. The semi-continuous casting device for large-scale high-alloyed magnesium rare earth alloy ingots according to claim 1 is characterized in that: The crystallizer includes a crystallizer inner sleeve and a crystallizer outer sleeve. A platform edge is provided along the circumference of the crystallizer inner sleeve. The top of the crystallizer outer sleeve is provided with an annular platform that cooperates with the platform edge and is embedded in the platform edge. The annular platform is located below the platform edge. The crystallizer outer sleeve is also provided with an outer shell connected to the annular platform for embedding the crystallizer inner sleeve.

4. The semi-continuous casting device for large-scale high-alloyed magnesium rare earth alloy ingots according to claim 3 is characterized in that: An annular cooling water trough is arranged between the crystallizer shell and the crystallizer inner sleeve, and a water inlet pipe is arranged on the crystallizer shell, and the water inlet pipe is communicated with the cooling water trough.

5. The semi-continuous casting device for large-scale high-alloyed magnesium rare earth alloy ingots according to claim 4 is characterized in that: The water inlet pipes are arranged on both sides of the crystallizer shell.

6. The semi-continuous casting device for large-scale high-alloyed magnesium rare earth alloy ingots according to claim 3 is characterized in that: A secondary cooling water outlet hole is arranged along the lower side of the inner sleeve of the crystallizer, and the water outlet hole is arranged obliquely, corresponding to the moving direction of the ingot during semi-continuous casting.

7. The semi-continuous casting device for large-scale high-alloyed magnesium rare earth alloy ingots according to claim 3 is characterized in that: The shape of the inner sleeve of the crystallizer is a trumpet shape that is wide at the top and narrow at the bottom, and the inclination angle is 1-6 degrees.

8. The semi-continuous casting device for large-scale high-alloyed magnesium rare earth alloy ingots according to claim 3 is characterized in that: An oil inlet pipeline is arranged between the platform edge and the annular platform, an oil groove is arranged along the circumference of the annular platform, and an oil lubrication spray hole communicating with the oil groove is arranged on the platform edge.

9. The semi-continuous casting device for large-scale high-alloyed magnesium rare earth alloy ingots according to claim 8 is characterized in that: The oil inlet pipeline is arranged on both sides of the inner sleeve of the crystallizer.

10. The semi-continuous casting device for large-scale high-alloyed magnesium rare earth alloy ingots according to claim 1 is characterized in that: The number of the diversion areas is six, and the six diversion areas are evenly distributed on the circumference of the vertical pipe.

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