Ingot mould device and ingot mould method for novel nitrogen-containing silicon steel plate-shaped cast ingot

Abstract

The invention discloses an ingot mould device and an ingot mould method for a novel nitrogen-controlled silicon steel plate-shaped cast ingot, and belongs to the technical field of smelting and casting. The technical problems that in the prior art, when a novel nitrogen-controlled steel plate-shaped cast ingot is smelted, element segregation is serious, and the defects of air holes and looseness occur in the cast ingot are solved. The ingot mould device provided by the invention is arranged at a molten steel outlet of a vacuum induction device; the ingot mould device comprises a plate-shaped water-cooling copper mould, an insulated feeder, a double-hole pouring funnel and an electromagnetic stirrer; the insulated feeder is positioned above the plate-shaped water-cooling copper mold, and the insulated feeder and the plate-shaped water-cooling copper mold are aligned and are communicated in inner cavities; after the double-hole pouring funnel and the insulated feeder are aligned and connected, inner cavities of the double-hole pouring funnel and the insulated feeder are communicated; and the electromagnetic stirrer is arranged on the outer side of the plate-shaped water-cooling copper mold. By means of the method, the novel nitrogen-controlled silicon steel plate-shaped cast ingot free of macroscopic defects and low in segregation can be stably prepared.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum induction special smelting and casting, and in particular to an ingot mold device and an ingot mold method for a novel nitrogen-containing silicon steel plate-shaped ingot. Background Art

[0002] Oriented silicon steel is an important metal material used in the transformer manufacturing industry. Its silicon content is about 3%, and the number of oxide inclusions in the steel is extremely low. It is usually designed to contain MnS, AlN, etc. as inhibitors to control the growth rate of grains. During the preparation process, it needs to go through multiple processes such as steelmaking, hot rolling, pickling, cold rolling, annealing, etc., and has high requirements for precise control of elements in steel and coordinated control between multiple processes of deformation and heat treatment. The magnetism of oriented silicon steel has a strong directionality, which makes it have the lowest iron loss value and the highest magnetic permeability in the rolling direction, and has a high magnetic induction value under a certain magnetizing field. The magnetic induction intensity of oriented silicon steel, as the most core factor restricting weight, volume and load loss, has become the main direction of the upgrading and development of oriented silicon steel materials.

[0003] In the process of development and design of new nitrogen-containing silicon steel, it is often necessary to optimize the content ratio of inhibitor-forming elements such as Mn, S, Al, N, Cu, Bi, Sn in the steel, control the content of C, O, H and other impurity elements, and ensure that the ingot has good metallurgical quality during the casting and solidification stage.

[0004] The plate-shaped ingot molds used in the prior art are usually made of cast iron, which can be used for the smelting and casting of most types of steel or alloys. However, in order to obtain a higher inhibitor content, new silicon steel contains a high content of nitrogen, and its solubility in steel decreases significantly as the temperature decreases, resulting in the formation of a large number of pores inside the ingot during solidification and serious segregation of alloy elements, which seriously reduces the yield rate and even causes the entire ingot to be scrapped. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a new ingot mold device and ingot mold method for nitrogen-controlled silicon steel plate-shaped ingots, so as to solve the problems of macroscopic defects such as loose pores inside the plate-shaped ingot and severe segregation of alloy elements during the vacuum induction melting and pouring stage.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions:

[0007] On the one hand, the present invention provides a novel ingot mold device for nitrogen-controlled silicon steel plate-shaped ingots, which is arranged at the outlet of molten steel of a vacuum induction device; the ingot mold device comprises a plate-shaped water-cooled copper mold, a heat-insulating riser, a double-hole pouring funnel and an electromagnetic stirrer;

[0008] The insulation riser is located above the plate-shaped water-cooled copper mold, the two are aligned and the inner cavities are connected; the double-hole pouring funnel is located above the insulation riser, the two are aligned and connected and their inner cavities are connected; the electromagnetic stirrer is located outside the plate-shaped water-cooled copper mold.

[0009] In a possible design, the plate-shaped water-cooled copper mold includes a U-shaped water-cooled side bottom plate and a first rectangular water-cooled panel and a second rectangular water-cooled panel with the same structure;

[0010] The first rectangular water-cooling panel and the second rectangular water-cooling panel are arranged parallel to each other on the two side surfaces of the U-shaped water-cooling side sealing bottom plate, and their bottoms are connected to the bottom surface of the U-shaped water-cooling side sealing bottom plate; the area enclosed by the three together constitutes a mold casting cavity for containing molten steel and ingots.

[0011] In one possible design, the electromagnetic stirrer includes a first plate-shaped electromagnetic stirrer and a second plate-shaped electromagnetic stirrer;

[0012] The first plate-shaped electromagnetic stirrer is located outside the first rectangular water-cooling panel; the second plate-shaped electromagnetic stirrer is located outside the second rectangular water-cooling panel; the first plate-shaped electromagnetic stirrer and the second plate-shaped electromagnetic stirrer are used to form a uniform magnetic field in the mold cavity.

[0013] In a possible design, the ingot mold device further includes two sets of upper and lower fastening clamps of identical structure;

[0014] The fastening fixture comprises a U-shaped fixture body; both ends of the U-shaped fixture body are provided with threaded holes and bolts;

[0015] The fastening clamp is used to fix the first rectangular water-cooling panel and the second rectangular water-cooling panel on the two side surfaces of the U-shaped water-cooling side bottom cover plate.

[0016] In a possible design, the double-hole pouring funnel includes a concave soup channel and a first funnel and a second funnel located on both sides of the concave soup channel; a first funnel outlet is provided at the bottom of the first funnel; and a second funnel outlet is provided at the bottom of the second funnel;

[0017] During pouring, the molten steel flows through the concave channel and enters the casting cavity of the plate-shaped water-cooled copper mold from the first funnel outlet and the second funnel outlet.

[0018] In a possible design, the first funnel outlet and the second funnel outlet are respectively located at one quarter and three quarters of the length of the double-hole pouring funnel; the concave soup channel is located in the middle position of the length of the double-hole pouring funnel.

[0019] In a possible design, the first funnel outlet and the second funnel outlet are both circular hole-shaped;

[0020] The diameters of the first funnel outlet and the second funnel outlet are both 25-30 mm.

[0021] In one possible design, the insulating riser has a hollow rectangular frustum;

[0022] Insulated risers are used to improve the shrinkage feeding efficiency of ingot solidification.

[0023] In a possible design, the outer wall of the insulating riser is made of cast iron, and the inner wall is made of a mixture of magnesia sand and water glass.

[0024] On the other hand, the present invention also provides a novel ingot mold method for nitrogen-controlled silicon steel plate-shaped ingots, using the novel ingot mold device for nitrogen-controlled silicon steel plate-shaped ingots mentioned above; the mold method comprises the following steps:

[0025] Step 1, placing the ingot mold device at the bottom of the vacuum induction furnace;

[0026] Step 2, charging the vacuum induction device and smelting to obtain molten steel;

[0027] Step 3, pouring the molten steel into the inner cavity containing the molten steel and the ingot through the double-hole pouring funnel to complete the casting;

[0028] Step 4: Cool the furnace under inert gas protection for 1 to 2 hours, open the ingot mold device, demould and take out the ingot to obtain a plate-shaped ingot.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] (1) The present invention is mainly aimed at obtaining plate-shaped ingots with good metallurgical quality by means of a vacuum induction furnace during the laboratory development and design stage of new steel grades. The plate-shaped water-cooled copper ingot mold of the present invention has the characteristics of high cooling strength and adjustable cooling water inlet temperature and flow rate; compared with the existing traditional cast iron plate-shaped ingot mold, the cooling and solidification speed of the molten steel is greatly improved, the initial grain size inside the ingot is reduced, the density of the ingot is high, and the possibility of forming defects such as pores and looseness is reduced, thereby ensuring that the material contains a high nitrogen content.

[0031] (2) The present invention arranges magnetic field agitators on both sides of the plate-shaped water-cooled copper mold, which can cause internal disturbance of the molten steel during the solidification process, break up the dendrites, increase the fine crystal nuclei and improve the nucleation rate, further reduce the grain size in the steel, and at the same time reduce the temperature gradient of the molten steel to reduce the solidification thermal stress.

[0032] (3) The plate-shaped water-cooled copper mold of the present invention is a flexibly assembled and disassembled device consisting of a U-shaped water-cooled side bottom plate and two rectangular water-cooled panels. Multiple sets of U-shaped water-cooled side bottom plates of different widths can be manufactured to match the rectangular water-cooled panels to meet the needs of different hot rolling compression ratio process parameters in the process of steel grade development. At the same time, by adjusting the parameters of the cooling water inlet temperature, flow rate and power-on frequency of the electromagnetic stirring device, a plate-shaped ingot with good metallurgical quality can be obtained.

[0033] (4) The present invention designs a double-hole pouring funnel for use with a plate-shaped water-cooled copper mold. The concave channel in the middle can buffer and divert the molten steel poured from the smelting crucible. Compared with a single-hole casting funnel, the double-hole casting can greatly reduce the flow time of the molten steel inside the plate-shaped ingot mold, accelerate the solidification speed and improve the metallurgical quality of the ingot. In addition, after the casting is completed, a small amount of molten steel will remain in the concave channel, which can be taken out after solidification and used to detect the chemical composition of the material.

[0034] (5) The ingot mold device and ingot mold method for the new type of nitrogen-controlled silicon steel plate-shaped ingot provided by the present invention realize the stable preparation of the new type of silicon steel plate-shaped ingot with good metallurgical quality by vacuum induction melting and casting, which is convenient for the subsequent development and research of the deformation heat treatment process of hot rolling-pickling-cold rolling-annealing of the new type of nitrogen-controlled silicon steel.

[0035] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the embodiments of the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0037] Figure 1 A schematic diagram of the structure of an ingot mold device for a novel nitrogen-containing silicon steel plate-shaped ingot provided by the present invention;

[0038] Figure 2 A top view of the plate-shaped water-cooled copper mold of the present invention;

[0039] Figure 3 It is a left side view of the ingot mold device of the present invention;

[0040] Figure 4 This is a microscopic morphology of the as-cast grains of the plate-shaped ingot prepared in Example 1;

[0041] Figure 5 This is a microscopic morphology of the as-cast grains of the plate-shaped ingot prepared in Comparative Example 1;

[0042] Figure 6 This is a microscopic morphology of the as-cast grains of the plate-shaped ingot prepared in Comparative Example 2;

[0043] Figure 7 This is a microscopic morphology of the as-cast grains of the plate-shaped ingot prepared in Example 2.

[0044] Reference numerals:

[0045] 1 - Plate-shaped water-cooled copper mold; 11 - U-shaped water-cooled side sealing bottom plate; 12 - Rectangular water-cooled panel; 2 - Insulating riser; 3 - Double-hole pouring funnel; 31 - First funnel outlet; 32 - Concave runner; 4 - Plate-shaped electromagnetic stirrer; 13 - First upper fastening clamp; 14 - Die-casting cavity. Detailed implementation manners

[0046] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0047] The present invention discloses an ingot mold device for a new type of nitrogen-controlled silicon steel plate-shaped ingot. The ingot mold device is arranged at the molten steel outlet of a vacuum induction device (for example, a vacuum induction furnace); the ingot mold device includes a plate-shaped water-cooled copper mold 1, an insulating riser 2, a double-hole pouring funnel 3 and an electromagnetic stirrer 4; the insulating riser 2 is located above the plate-shaped water-cooled copper mold 1, and after they are aligned and connected, their inner cavities are communicated with each other; the double-hole pouring funnel 3 is arranged above the insulating riser 2, and after they are aligned and connected, their inner cavities are communicated; the electromagnetic stirrer 4 is arranged outside the plate-shaped water-cooled copper mold 1.

[0048] Specifically, the above-mentioned plate-shaped water-cooled copper mold 1 is a hollow structure with an open top, and the inside of the plate-shaped water-cooled copper mold 1 is a cavity; the insulating riser 2 is located directly above the plate-shaped water-cooled copper mold 1, and after they are aligned and connected, the inner cavity of the insulating riser 2 is communicated with the cavity of the plate-shaped water-cooled copper mold 1; the vacuum induction furnace is used to melt the raw materials of the new type of nitrogen-controlled silicon steel into molten steel with a high superheat degree. After melting, the molten steel with a high superheat degree enters the cavity of the plate-shaped water-cooled copper mold 1 through the double-hole pouring funnel 3 and the insulating riser 2. Under the strong cooling action of its cooling water, the molten steel quickly solidifies and quickly compensates for shrinkage to eliminate the macroscopic defects of internal porosity and shrinkage cavities. And under the stirring action of the uniform magnetic field generated by the electromagnetic stirrer 4, the molten steel can eliminate alloy element segregation.

[0049] In the prior art, when preparing a new type of nitrogen-controlled silicon steel ingot, the molten steel after melting is directly poured into a plate-shaped ingot mold made of cast iron, resulting in a large number of pores inside the cast billet and serious alloy element segregation. Compared with the prior art, the present invention uses the plate-shaped water-cooled copper mold 1 to quickly cool and cast the molten steel with a high superheat degree, and uses the electromagnetic stirrer 4 to stir it, which can realize the stable preparation of a plate-shaped ingot without macroscopic defects and low segregation; in addition, the present invention uses a vacuum induction furnace as the primary melting equipment, which can strictly control the content of active metal elements such as aluminum and titanium in the alloy, reduce the content of hydrogen, oxygen and nitrogen in the alloy, so as to obtain an ingot with accurate alloy element content and high purity.

[0050] It should also be noted that the ingot prepared by the present invention can be directly rolled and heat treated without forging. The components of the novel nitrogen-controlled silicon steel of the present invention include, by weight percentage: C: 0.05-0.07wt.%, Si: 0.8-1.2wt.%, Mn: 0.12-0.16wt.%, Al: 0.02-0.03wt.%, N: 0.020-0.028wt.%, S: 0.008-0.012wt.%, Cu: 0.1-0.12wt.%, Sn: 0.1-0.12wt.%, Bi: 0.002-0.006wt.%, and the balance is Fe and unavoidable impurities.

[0051] In order to quickly cool the molten steel to form an ingot, the plate-shaped water-cooled copper mold 1 of the present invention includes a U-shaped water-cooled side bottom plate 11, a first rectangular water-cooled panel and a second rectangular water-cooled panel with the same structure; the first rectangular water-cooled panel and the second rectangular water-cooled panel are arranged parallel to each other on the two side surfaces of the U-shaped water-cooled side bottom plate 11 and their bottoms are connected to the bottom surface of the U-shaped water-cooled side bottom plate 11; the area enclosed by the three together constitutes a mold casting cavity 14 for containing molten steel and ingots.

[0052] Specifically, Figure 1 and Figure 2 As shown, the U-shaped water-cooled side bottom plate 11 provides the bottom surface and two symmetrical narrow side surfaces of the mold casting cavity 14, and the two rectangular water-cooled panels provide two symmetrical wide surfaces of the mold casting cavity 14. The five planes together form a cavity that can contain molten steel / ingots.

[0053] Compared with the prior art, the present invention is provided with a U-shaped water-cooled side bottom plate 11 and rectangular water-cooled panels 12 on both sides thereof. On the one hand, a mold casting cavity 14 for containing molten steel and ingots can be formed. The forced rapid cooling effect of the plate-shaped water-cooled copper mold 1 and the stirring effect of the uniform magnetic field generated by the electromagnetic stirrer 4 can make the molten steel quickly solidify into a plate-shaped ingot with good metallurgical quality; on the other hand, the present invention can flexibly assemble and disassemble the device by arranging two rectangular water-cooled panels 12 on both sides of the U-shaped water-cooled side bottom plate 11, and can produce multiple groups of U-shaped water-cooled side bottom plates 11 with different widths to match the rectangular water-cooled panels 12 to meet the needs of different hot rolling compression ratio process parameters in the process of steel grade development. At the same time, by adjusting the parameters of the cooling water inlet temperature, flow rate and power-on frequency of the electromagnetic stirring device, a plate-shaped ingot with good metallurgical quality can be obtained.

[0054] It is also necessary to emphasize that the present invention can rapidly solidify the molten steel by providing a plate-shaped water-cooled copper mold 1. When the molten steel solidifies, due to the high degree of supercooling and the fast cooling rate, it can not only increase the solidification nucleation rate, but also is not easy to have obvious component segregation due to selective crystallization, making the alloy composition more uniform. At the same time, the grain size in the rapidly solidified steel is small and the size distribution is uniform.

[0055] It should be noted that the material of the U-shaped water-cooled side bottom plate 11 and the rectangular water-cooled panels 12 on both sides of the present invention are forged copper. Compared with cast copper, the plate-shaped water-cooled copper mold 1 of the present invention adopts forged copper because: the forged copper parts are made by hammering with copper hammers under high temperature and high pressure, and have dense structure, high density, high hardness, wear resistance, loss resistance, and good dimensional stability.

[0056] The inner bottom length of the U-shaped water-cooled side bottom plate 11 of the present invention is 360 mm, the inner bottom width is 30 mm, and the inner height is 180 mm, which is the same as the ingot mold cavity size of the plate-shaped water-cooled copper mold 1.

[0057] The maximum amount of molten steel that can be poured at a time by the casting mold device of the present invention is 15 kg. The geometric dimensions and nominal capacity of the ingot mold can be adjusted according to the requirements of steel smelting and subsequent hot processing.

[0058] In order to stir the molten steel in the mold cavity 14, the electromagnetic stirrer 4 of the present invention includes a first plate-shaped electromagnetic stirrer and a second plate-shaped electromagnetic stirrer; the first plate-shaped electromagnetic stirrer is located on the outside of the first rectangular water-cooling panel; the second plate-shaped electromagnetic stirrer is located on the outside of the second rectangular water-cooling panel; the first plate-shaped electromagnetic stirrer and the second plate-shaped electromagnetic stirrer are used to form a uniform magnetic field in the mold cavity 14 and thus stir the molten steel.

[0059] Specifically, the first plate-shaped electromagnetic stirrer and the second plate-shaped electromagnetic stirrer are both double-sided traveling wave magnetic field stirrers, and the power-on frequency thereof is 20-60 Hz; the two electromagnetic stirrers are respectively fixed to the outer sides of two rectangular water-cooled panels 12 of the plate-shaped water-cooled copper mold 1 .

[0060] Compared with the prior art, the present invention arranges a first plate-shaped electromagnetic stirrer on the outer side of the first rectangular water-cooled panel and a second plate-shaped electromagnetic stirrer on the outer side of the second rectangular water-cooled panel, thereby ensuring that the magnetic field formed in the mold casting cavity 14 is a uniform magnetic field in which the magnetic flux lines are parallel to the horizontal plane of the molten steel, thereby making the solidification quality (including grain size and degree of element homogenization) of the plate-shaped new silicon steel ingot have good consistency from bottom to top.

[0061] In order to fix the two rectangular water-cooling panels 12 on both sides of the U-shaped water-cooling side bottom plate 11, the ingot mold device of the present invention also includes two sets of upper and lower fastening clamps with the same structure; the fastening clamp includes a U-shaped clamp body; both ends of the U-shaped clamp body are provided with threaded holes and bolts; the fastening clamp is used to fix the first rectangular water-cooling panel and the second rectangular water-cooling panel on the two side surfaces of the U-shaped water-cooling side bottom plate 11.

[0062] Specifically, Figure 2 and Figure 3 As shown, the upper group of fastening clamps includes a first upper fastening clamp 13 and a second upper fastening clamp; the lower group of fastening clamps includes a first lower fastening clamp and a second lower fastening clamp; the first upper fastening clamp 13 and the second upper fastening clamp are symmetrically arranged and both are arranged at the upper half of the water-cooled copper mold; the first lower fastening clamp and the second lower fastening clamp are symmetrically arranged and both are arranged at the lower half of the water-cooled copper mold; the four fastening clamps all include a U-shaped clamp body, and threaded holes are arranged at both ends of the U-shaped clamp body, and bolts are arranged in the threaded holes; when fixing, first set the first rectangular water-cooling panel and the second rectangular water-cooling panel parallel to each other, A first plate-shaped electromagnetic stirrer is arranged on the two side surfaces of the U-shaped water-cooled side sealing bottom plate 11, and a second plate-shaped electromagnetic stirrer is arranged on the outer side surface of the first rectangular water-cooled panel, and a second plate-shaped electromagnetic stirrer is arranged on the outer side surface of the second rectangular water-cooled panel. Then, the U-shaped clamp bodies of each fastening clamp are inserted from both sides of the side sealing plate of the U-shaped water-cooled side sealing bottom plate 11, and each bolt is tightened to fix the two rectangular water-cooled panels 12 and the two electromagnetic stirrers on the U-shaped water-cooled side sealing bottom plate 11, so that the two rectangular water-cooled panels 12 and the U-shaped water-cooled side sealing bottom plate 11 together constitute a mold casting cavity 14 for containing molten steel and ingots.

[0063] It should be noted that the material of the upper and lower sets of fastening clamps of the present invention is stainless steel. This is because stainless steel has good strength, toughness, fatigue resistance and good corrosion resistance, and has a smooth and beautiful surface.

[0064] In order to achieve rapid cooling of the molten steel in the mold casting cavity 14, the U-shaped water-cooled side bottom plate 11, the first rectangular water-cooled panel and the second rectangular water-cooled panel of the present invention are all connected to cooling water inlet and outlet pipelines, and flow meters and thermometers are installed on the cooling water inlet and outlet pipelines, so that the inlet and outlet flow rates and inlet and outlet water temperature parameters of the cooling water can be monitored in real time.

[0065] It should be noted that the insulating riser 2 of the present invention has a hollow rectangular cone shape and is used to improve the shrinkage compensation efficiency of the ingot solidification. The outer wall of the insulating riser 2 is made of cast iron, and the inner wall is made of a mixture of magnesia and water glass.

[0066] Specifically, the above-mentioned insulation riser 2 has an appearance of a hollow rectangular cone, which is narrow at the top and wide at the bottom. The top is tightly connected to the double-hole pouring funnel 3, and the bottom size is the same as that of the plate-shaped water-cooled copper mold 1 and the two are installed in alignment. The outer wall of the insulation riser 2 is made of cast iron, and the interior is made of a mixture of magnesia sand and water glass. The magnesia sand acts as a binder. The insulation riser 2 can improve the shrinkage compensation efficiency of the ingot solidification.

[0067] In order to buffer and distribute the pouring molten steel, the double-hole pouring funnel 3 of the present invention includes a concave channel 32 and a first funnel and a second funnel located on both sides of the concave channel 32; a first funnel outlet 31 is provided at the bottom of the first funnel; a second funnel outlet is provided at the bottom of the second funnel; during pouring, the molten steel flows through the concave channel 32 and enters the casting cavity 14 of the plate-shaped water-cooled copper mold 1 from the first funnel outlet 31 and the second funnel outlet.

[0068] Specifically, the first funnel and the second funnel of the present invention have the same structure and are symmetrically arranged, and the concave channel 32 is located in the middle of the two. The molten steel smelted by the vacuum induction furnace enters the first funnel and the second funnel respectively after being buffered and distributed by the concave channel 32, and enters the mold casting cavity 14 through the first funnel outlet 31 and the second circular hole funnel outlet.

[0069] Compared with the prior art, the double-hole pouring funnel 3 of the present invention can play a role in buffering the molten steel during the pouring of the molten steel.

[0070] It should be noted that the first funnel outlet 31 and the second funnel outlet of the present invention are respectively located at one quarter and three quarters of the length direction of the double-hole pouring funnel 3; the concave soup channel 32 is located at the middle position of the length direction of the double-hole pouring funnel 3. In addition, the double-hole pouring funnel 3 is made of magnesium, which has high temperature resistance and good thermal stability.

[0071] Compared with the prior art, the present invention pours molten steel into the ingot mold through the double-hole pouring funnel 3, so that the molten steel flows and solidifies quickly and evenly in the ingot mold, which can reduce segregation.

[0072] It should be noted that the first funnel outlet 31 and the second funnel outlet are in the shape of circular holes, and their diameters are both 24-26 mm.

[0073] The present invention also provides a novel ingot mold method for nitrogen-controlled silicon steel plate-shaped ingots, which uses the novel ingot mold device for nitrogen-controlled silicon steel plate-shaped ingots; the ingot mold method comprises the following steps:

[0074] Step 1, placing a vacuum induction melting ingot mold device at the bottom of a vacuum induction furnace at a molten steel outlet;

[0075] Step 2, charging the vacuum induction furnace and performing vacuum smelting to obtain molten steel;

[0076] In the above step 1, before smelting in a vacuum induction furnace, industrial pure iron is first added to a magnesium crucible for iron washing. After the iron washing is completed, the materials are mixed according to the target composition of the new nitrogen-controlled silicon steel and in combination with various metals or alloy materials and element yields. According to different feeding timings, raw materials of industrial pure iron, photoelectric carbon, high-purity silicon, metallic copper, metallic tin, and iron sulfide are loaded into the crucible, and raw materials of aluminum particles, manganese-nitrogen alloy, and metallic bismuth are loaded into a secondary feeding box.

[0077] In the above step 1, the mechanical pump and the Roots pump are turned on in turn to evacuate the multi-stage vacuum system. When the vacuum degree in the furnace is lower than 10Pa, the power-on vacuum induction melting is started. The power-on vacuum induction melting includes three stages: melting period, refining period, and alloying period. According to the smelting requirements, the smelting tasks of melting raw materials, refining and degassing, stirring molten steel, and adding alloy materials are completed. Inert gas protection is filled in and the electric power is adjusted to make the temperature of the molten steel reach the tapping temperature.

[0078] In the above step 1, the components of the novel nitrogen-controlled silicon steel include, by weight percentage: C: 0.05-0.07wt.%, Si: 0.8-1.2wt.%, Mn: 0.12-0.16wt.%, Al: 0.02-0.03wt.%, N: 0.020-0.028wt.%, S: 0.008-0.012wt.%, Cu: 0.1-0.12wt.%, Sn: 0.1-0.12wt.%, Bi: 0.002-0.006wt.%, and the remainder is Fe and unavoidable impurities.

[0079] Step 3, pouring the molten steel into the cavity containing the molten steel and the ingot through the double-hole pouring funnel 3 to complete the casting;

[0080] In the above step 3, after the vacuum induction melting is completed, the electromagnetic stirrer 4 of the plate-shaped water-cooled copper mold 1 is turned on, and the electric power is adjusted so that the temperature of the molten steel reaches a high superheated temperature, and then the crucible is tilted to start pouring, and the molten steel enters the plate-shaped water-cooled copper mold 1 through the double-hole pouring funnel 3 and the insulation riser 2.

[0081] In step 3 above, the inlet and outlet temperature difference of the cooling water is 2-3°C, and the cooling water flow rate is 40-80m 3 / h, cooling capacity (kW) = cooling water flow (m 3 / h)×specific heat capacity of water (kJ / kg·℃)×temperature difference (℃); the specific heat capacity of water is usually 4.186kJ / kg·C; the cooling capacity of the water-cooled copper mold is 335kW~1005kW.

[0082] Step 4: Cool in the furnace under inert gas protection for 1 to 2 hours, open the ingot mold device, demould and take out the ingot to obtain a plate-shaped ingot.

[0083] In the above step 4, the electromagnetic stirrer 4 outside the plate-shaped water-cooled copper mold 1 is turned on to a preset stirring frequency of 20 to 60 Hz, the melting crucible is slowly tilted, and casting begins. The molten steel is poured into the cavity of the plate-shaped water-cooled copper mold 1 through the double-hole pouring funnel 3 and the insulation riser 2, and the casting is completed.

[0084] In the above step 4, the furnace is cooled for 1 to 2 hours under inert gas protection conditions, the furnace body vent valve is opened to break the air, the cooling water is turned off, the double-hole pouring funnel 3 and the insulation riser 2 are removed in turn, and the plate-shaped water-cooled copper mold 1 and the plate-shaped ingot are taken out of the furnace, and the fastening clamps and the rectangular water-cooled panel 12 are disassembled to demold and take out the ingot.

[0085] In summary, the present invention utilizes the strong cooling effect of cooling water to rapidly solidify the molten steel, rapidly compensates for the shrinkage of the highly superheated molten steel to eliminate the macroscopic defects of internal porosity and shrinkage, and eliminates the segregation of alloy elements under the action of electromagnetic stirring (electromagnetic stirring can increase the equiaxed crystal rate of the ingot and refine the solidification structure, thereby significantly reducing the segregation of alloy elements.).

[0086] The ingot mold device and ingot mold method of the present invention are mainly designed for smelting new nitrogen-controlled silicon steel plate-shaped metal ingots in a 10-50kg vacuum induction furnace (ZLG type), and are suitable for reducing solidification defects of plate-shaped ingots and improving their metallurgical quality.

[0087] Example 1

[0088] This embodiment provides a novel ingot mold device and ingot mold method for nitrogen-controlled silicon steel plate-shaped ingots, which are used to smelt novel oriented silicon steel (nitrogen content in the steel is in the range of 0.012 to 0.016 wt.%) on a ZGL type 50 kg vacuum induction furnace and complete the plate-shaped ingot casting operation, which includes the following steps:

[0089] Step 1, placing the ingot mold device at the steel liquid outlet position at the bottom of the vacuum induction furnace;

[0090] Use two sets of upper and lower fastening clamps to fix two rectangular water-cooled panels 12 and two plate-shaped electromagnetic stirrers on both sides of the U-shaped water-cooled side bottom plate 11 to complete the installation of the plate-shaped water-cooled copper mold 1; then, use an overhead crane to move the installed plate-shaped water-cooled copper mold 1 to a suitable position of the vacuum induction furnace; then, connect the cooling water inlet and outlet pipes of the U-shaped water-cooled side bottom plate 11 and the two rectangular water-cooled panels 12 and the external lines of the two plate-shaped electromagnetic stirrers; finally, install the insulating riser 2 directly above the plate-shaped water-cooled copper mold 1 and install the double-hole pouring funnel 3 above the insulating riser 2. At this point, the overall installation of the ingot mold device is completed.

[0091] Step 2, charging the vacuum induction furnace and performing vacuum smelting to obtain molten steel;

[0092] Before smelting in the vacuum induction furnace, industrial pure iron is added into the magnesium crucible for iron washing to ensure that the vacuum induction furnace melting crucible is clean and to prevent impurity elements in the crucible from contaminating the smelted steel materials.

[0093] The amount of industrial pure iron and various alloy raw materials to be charged is calculated based on a charge of 15 kg and the target composition of the new silicon steel (in terms of mass percentage, containing 0.06% C, 1.2% Si, 0.15% Mn, 0.010% S, 0.025% Al, 0.021% N, 0.002% Bi, 0.1% Sn, 0.1% Cu, and the rest is Fe). 14.85 kg of industrial pure iron, 165 g of high-purity silicon, 1 g of iron sulfide, 15 g of metallic tin, and 15 g of metallic copper are charged into the bottom of the smelting crucible, and 10 g of manganese-nitrogen alloy (nitrogen content is about 15 wt.%), 6 g of electrolytic manganese, 4 g of metallic aluminum particles, and 7 g of photoelectric carbon are charged into the material box at the top of the vacuum induction furnace;

[0094] The vacuum smelting process includes: step 21, closing the cover of the vacuum induction furnace, opening the vacuum systems of the furnace body in turn, and evacuating the vacuum until the vacuum degree is less than 0.5Pa; step 22, turning on the power supply to start powering on, the power of the vacuum induction furnace is gradually increased from the initial 20kW to 60kW, the raw materials inside the crucible of the vacuum induction furnace are induction heated, the melting period smelting begins, the metal raw materials are gradually melted, and the melting period lasts for 0.75 hours; step 23, the melting period ends, the refining period smelting begins, and the power is reduced , the electric power during the refining period is maintained at 50kW, the non-contact optical thermometer above the peephole of the vacuum induction furnace cover is used to monitor the temperature of the molten steel in real time, and the electric power is dynamically adjusted to maintain the temperature of the molten steel at 1600°C. The refining period is 0.25 hours; step 24, the refining period ends, the alloying period smelting begins, the electric power is reduced to 45kW, 0.02MPa argon is charged as a protective gas, the alloy raw materials in the top box of the vacuum induction furnace are added to the molten steel in the melting crucible, and the temperature is kept for 5 minutes;

[0095] Step 3, pouring the molten steel into the cavity containing the molten steel and the ingot through the double-hole pouring funnel 3 to complete the casting;

[0096] Open the cooling water system of the plate-shaped water-cooled copper mold 1, and adjust the cooling water inlet temperature and flow rate to the set value (inlet temperature 25°C, inlet flow rate 35m 3 / h), turn on the power switch of the electromagnetic stirrer 4, and adjust its frequency to 30Hz; adjust the input power, the temperature of the molten steel is 1530℃, slowly tilt the melting crucible in the furnace to start pouring, the molten steel accurately flows through the concave soup channel 32 in the middle of the double-hole pouring funnel 3 to the first funnel outlet 31 and the second funnel outlet on both sides quickly and continuously, and passes through the insulation riser 2 into the mold casting cavity 14 of the plate-shaped water-cooled copper mold 1. The molten steel is quickly solidified into a plate-shaped ingot under the action of cooling water and electromagnetic stirring.

[0097] Step 4: Cool in the furnace under inert gas protection for 1.5 hours, open the ingot mold device, demould and take out the ingot to obtain a plate-shaped ingot.

[0098] Maintain the vacuum and argon filling conditions for 1 hour, turn off the cooling water of the plate-shaped water-cooled copper mold 1 and the power switch of the electromagnetic stirrer 4, open the furnace body vent valve to break the air, remove the double-hole pouring funnel 3 and the insulation riser 2, use the overhead crane to take out the plate-shaped water-cooled copper mold 1 and disassemble it, and complete the demolding operation. At this time, the vacuum induction furnace smelting of 15kg new silicon steel plate-shaped ingot is completed.

[0099] The plate-shaped ingot was cut longitudinally. There were no pores or cracks on the cross section. The low-power organization analysis was performed to calculate the grain size and Mn element segregation coefficient. The results are shown in Table 1. The microscopic morphology of the as-cast grains under an optical microscope is shown in Figure 4 shown.

[0100] Example 2

[0101] This embodiment provides a novel ingot mold device and ingot mold method for nitrogen-controlled silicon steel plate-shaped ingots, which are used to smelt novel oriented silicon steel (nitrogen content in the steel is in the range of 0.012 to 0.016 wt.%) on a ZGL type 50 kg vacuum induction furnace and complete the plate-shaped ingot casting operation, which includes the following steps:

[0102] Step 1, placing the ingot mold device at the steel liquid outlet position at the bottom of the vacuum induction furnace;

[0103] Use two sets of upper and lower fastening clamps to fix two rectangular water-cooled panels 12 and two plate-shaped electromagnetic stirrers on both sides of the U-shaped water-cooled side bottom plate 11 to complete the installation of the plate-shaped water-cooled copper mold 1; then, use an overhead crane to move the installed plate-shaped water-cooled copper mold 1 to a suitable position of the vacuum induction furnace; then, connect the cooling water inlet and outlet pipes of the U-shaped water-cooled side bottom plate 11 and the two rectangular water-cooled panels 12 and the external lines of the two plate-shaped electromagnetic stirrers; finally, install the insulating riser 2 directly above the plate-shaped water-cooled copper mold 1 and install the double-hole pouring funnel 3 above the insulating riser 2. At this point, the overall installation of the ingot mold device is completed.

[0104] Step 2, charging the vacuum induction furnace and performing vacuum smelting to obtain molten steel;

[0105] Before smelting in the vacuum induction furnace, industrial pure iron is added into the magnesium crucible for iron washing to ensure that the vacuum induction furnace melting crucible is clean and to prevent impurity elements in the crucible from contaminating the smelted steel materials.

[0106] Based on a charge of 15 kg and in accordance with the target composition of the new silicon steel (in mass percentage, 0.06% C, 1.2% Si, 0.15% Mn, 0.010% S, 0.025% Al, 0.027% N, 0.004% Bi, 0.1% Sn, 0.1% Cu, and the rest Fe), the charge of industrial pure iron and various alloy raw materials is calculated.

[0107] The vacuum smelting process includes: step 21, closing the cover of the vacuum induction furnace, opening the vacuum systems of the furnace body in turn, and evacuating the vacuum until the vacuum degree is less than 0.5Pa; step 22, turning on the power supply to start powering on, the power of the vacuum induction furnace is gradually increased from the initial 20kW to 60kW, the raw materials inside the crucible of the vacuum induction furnace are induction heated, the melting period smelting begins, the metal raw materials are gradually melted, and the melting period lasts for 0.75 hours; step 23, the melting period ends, the refining period smelting begins, and the power is reduced , the electric power during the refining period is maintained at 55kW, the temperature of the molten steel is monitored in real time by a non-contact optical thermometer above the peephole of the vacuum induction furnace cover, and the electric power is dynamically adjusted to maintain the temperature of the molten steel at 1610°C. The refining period is 0.25 hours; Step 24, the refining period ends, the alloying period smelting begins, the electric power is reduced to 45kW, 0.02MPa argon is charged as a protective gas, the alloy raw materials in the material box at the top of the vacuum induction furnace are added to the molten steel in the melting crucible, and the temperature is kept for 5 minutes;

[0108] Step 3, pouring the molten steel into the cavity containing the molten steel and the ingot through the double-hole pouring funnel 3 to complete the casting;

[0109] Open the cooling water system of the plate-shaped water-cooled copper mold 1, and adjust the cooling water inlet temperature and flow rate to the set values ​​(inlet temperature 25°C, inlet flow rate 50m 3 / h), turn on the power switch of the electromagnetic stirrer 4, and adjust its frequency to 40Hz; adjust the input power, the temperature of the molten steel is 1550℃, slowly tilt the melting crucible in the furnace to start pouring, the molten steel accurately flows through the concave soup channel 32 in the middle of the double-hole pouring funnel 3 to the first funnel outlet 31 and the second funnel outlet on both sides quickly and continuously, and passes through the insulation riser 2 into the mold casting cavity 14 of the plate-shaped water-cooled copper mold 1. The molten steel is quickly solidified into a plate-shaped ingot under the action of cooling water and electromagnetic stirring.

[0110] Step 4: Cool in the furnace under inert gas protection for 2 hours, open the ingot mold device, demould and take out the ingot to obtain a plate-shaped ingot.

[0111] Maintain the vacuum and argon filling conditions for 1 hour, turn off the cooling water of the plate-shaped water-cooled copper mold 1 and the power switch of the electromagnetic stirrer 4, open the furnace body vent valve to break the air, remove the double-hole pouring funnel 3 and the insulation riser 2, use the overhead crane to take out the plate-shaped water-cooled copper mold 1 and disassemble it, and complete the demolding operation. At this time, the vacuum induction furnace smelting of 15kg new silicon steel plate-shaped ingot is completed.

[0112] The plate-shaped ingot was cut longitudinally. The average grain size, macroscopic defects and Mn segregation coefficient of the ingot are shown in Table 1. The microscopic morphology of the as-cast grains under an optical microscope is shown in Table 1. Figure 7 shown.

[0113] Comparative Example 1

[0114] This comparative example 1 is basically the same as Example 1, except that: the power switch of the electromagnetic stirrer 4 is not turned on in step 3, that is, the electromagnetic stirring operation is not performed during the solidification of the molten steel. Similarly, the ingot obtained in this comparative example 1 is subjected to the same characterization analysis as in Example 1. The results are shown in Table 1. The microscopic morphology of the cast grains under an optical microscope is shown in Figure 5 shown.

[0115] Comparative Example 2

[0116] This comparative example 2 is basically the same as Example 1, except that: in step 2, a water-free cast iron ingot mold with the same geometric dimensions of the ingot is used to replace the plate-shaped water-cooled copper mold 1 device of the present invention, and the ingot mold operation using the ingot mold device of the present invention in step 3 is cancelled. Similarly, the ingot obtained in this comparative example 2 is subjected to the same characterization analysis as in Example 1, and the results are shown in Table 1. The microscopic morphology of the cast grains under an optical microscope is shown in Figure 6 shown.

[0117] Table 1 Characterization and analysis results of the castings of the embodiments and comparative examples

[0118]

[0119] Through Example 1 and Example 2 and two comparative examples, it is found that the casting operation of the new nitrogen-controlled silicon steel material is completed by using a plate-shaped water-cooled copper mold 1 with an electromagnetic stirrer 4. Rapid solidification and electromagnetic stirring can effectively refine the cast grain size and reduce the possibility of nitrogen precipitation and escape caused by the reduction of nitrogen solubility to form pores in the ingot. In addition, on the basis of ensuring smooth casting, the local cooling time of the alloy is effectively shortened, the non-equilibrium solidification diffusion kinetic energy of the segregated elements in the steel is reduced, and the uniformity of the distribution of alloy elements is improved.

[0120] In summary, the ingot mold device and ingot mold method for the new nitrogen-controlled silicon steel plate-shaped ingot provided by the present invention are suitable for vacuum smelting and casting in the laboratory development stage of new silicon steel and other new steel types. With the help of high-intensity water cooling and electromagnetic stirring, the rapid solidification of molten steel is achieved to obtain plate-shaped ingots with fine grains and high density, which is conducive to the development of new oriented silicon steel materials. The plate-shaped ingots with good metallurgical quality can be directly connected to the subsequent hot rolling process research.

[0121] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A novel ingot mold device for nitrogen-controlled silicon steel plate-shaped ingot, characterized in that: The ingot mold device is arranged at the molten steel outlet of the vacuum induction device; the ingot mold device comprises a plate-shaped water-cooled copper mold, a heat-insulating riser, a double-hole pouring funnel and an electromagnetic stirrer; The insulation riser is located above the plate-shaped water-cooled copper mold, the two are aligned and arranged, and the inner cavities are connected; the double-hole pouring funnel is arranged above the insulation riser, and the two are aligned and connected, and their inner cavities are connected; the electromagnetic stirrer is arranged on the outside of the plate-shaped water-cooled copper mold.

2. The ingot mold device for the new type of nitrogen-controlled silicon steel plate-shaped ingot according to claim 1 is characterized in that: The plate-shaped water-cooled copper mold comprises a U-shaped water-cooled side bottom plate and a first rectangular water-cooled panel and a second rectangular water-cooled panel having the same structure; The first rectangular water-cooling panel and the second rectangular water-cooling panel are arranged parallel to each other on the two side surfaces of the U-shaped water-cooling side bottom plate and their bottoms are connected to the bottom plate of the U-shaped water-cooling side bottom plate; the area enclosed by the three together constitutes a mold casting cavity for containing molten steel and ingots.

3. The ingot mold device for the new type of nitrogen-controlled silicon steel plate-shaped ingot according to claim 2 is characterized in that: The electromagnetic stirrer comprises a first plate-shaped electromagnetic stirrer and a second plate-shaped electromagnetic stirrer; The first plate-shaped electromagnetic stirrer is located outside the first rectangular water-cooled panel; the second plate-shaped electromagnetic stirrer is located outside the second rectangular water-cooled panel; the first plate-shaped electromagnetic stirrer and the second plate-shaped electromagnetic stirrer are used to form a uniform magnetic field in the mold casting cavity to stir the molten steel.

4. The ingot mold device for the new type of nitrogen-controlled silicon steel plate-shaped ingot according to claim 3 is characterized in that: The ingot mold device also includes two sets of upper and lower fastening clamps with the same structure; The fastening fixture comprises a U-shaped fixture body; both ends of the U-shaped fixture body are provided with threaded holes and bolts; The fastening fixture is used to fix the first rectangular water-cooling panel and the second rectangular water-cooling panel on two side surfaces of the U-shaped water-cooling side bottom cover plate.

5. The ingot mold device for the new type of nitrogen-controlled silicon steel plate-shaped ingot according to claim 2 is characterized in that: The double-hole pouring funnel comprises a concave soup channel and a first funnel and a second funnel located on both sides of the concave soup channel; a first funnel outlet is provided at the bottom of the first funnel; and a second funnel outlet is provided at the bottom of the second funnel; During pouring, the molten steel flows through the concave channel and enters the casting cavity of the plate-shaped water-cooled copper mold from the first funnel outlet and the second funnel outlet.

6. The ingot mold device for the new type of nitrogen-controlled silicon steel plate-shaped ingot according to claim 5 is characterized in that: The first funnel outlet and the second funnel outlet are respectively located at one quarter and three quarters of the length direction of the double-hole pouring funnel; the concave soup channel is located at the middle position of the length direction of the double-hole pouring funnel.

7. The ingot mold device for the new type of nitrogen-controlled silicon steel plate-shaped ingot according to claim 6 is characterized in that: The first funnel outlet and the second funnel outlet are both in the shape of circular holes; The diameters of the first funnel outlet and the second funnel outlet are both 25-30 mm.

8. The ingot mold device for the new type of nitrogen-controlled silicon steel plate-shaped ingot according to claim 1 is characterized in that: The shape of the thermal insulation riser is a hollow rectangular frustum; The heat-insulating riser is used to improve the shrinkage-feeding efficiency of the ingot solidification.

9. The ingot mold device for the new type of nitrogen-controlled silicon steel plate-shaped ingot according to claim 8, characterized in that: The outer wall of the thermal insulation riser is made of cast iron, and the inner wall is made of a mixture of magnesia sand and water glass.

10. A novel ingot mold method for nitrogen-controlled silicon steel plate-shaped ingots, using the novel ingot mold device for nitrogen-controlled silicon steel plate-shaped ingots according to any one of claims 1 to 9; the mold method comprises the following steps: Step 1, placing the ingot mold device at the bottom of the vacuum induction furnace; Step 2, charging the vacuum induction device and smelting to obtain molten steel; Step 3, pouring the molten steel into the inner cavity containing the molten steel and the ingot through the double-hole pouring funnel to complete the casting; Step 4: Cool the furnace under inert gas protection for 1 to 2 hours, open the ingot mold device, demould and take out the ingot to obtain a plate-shaped ingot.

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