Method for preparing electrical steel and electrical steel

Abstract

The present application discloses a method for preparing electrical steel and the electrical steel. The method comprises: continuously casting molten steel from a tundish through a chamfered crystallizer at a speed of 1.2 to 1.5 m / min to obtain a continuously cast billet; wherein continuously casting the molten steel from the tundish through the chamfered crystallizer at a speed of 1.2 to 1.5 m / min comprises: cooling the molten steel in the chamfered crystallizer, wherein the cooling comprises using first cooling water in a first direction and second cooling water in a second direction; the flow rate of the first cooling water is 4200 to 4900 L / min, and the flow rate of the second cooling water is 580 to 650 L / min. The method of the present application can significantly improve the spot-like peeling phenomenon on the edge of the electrical steel, improve the yield rate of the electrical steel, and improve the overall performance of the electrical steel.

Description

Technical Field

[0001] The present application belongs to the technical field of steel plate smelting, and specifically relates to a preparation method of electrical steel and electrical steel. Background Art

[0002] Pitting and peeling on the edges of electrical steel can severely impact its performance and yield. For example, this can expose the base material. Damage to the surface oxide layer or coating can affect the steel's iron loss characteristics, leading to flux leakage or increased magnetic losses, impacting electromagnetic performance. Pitting and peeling can also create uneven edge defects that can cause magnetic discontinuities and increase eddy current losses. Due to coating damage or exposed base material in the peeling area, localized eddy currents can increase, affecting high-frequency performance and reducing the material's magnetic permeability.

[0003] The performance of electrical steel with spot-like peeling on the edges is affected by the extent, depth, and area of ​​the peeling. Therefore, improvements are urgently needed. Summary of the Invention

[0004] In view of this, the present application provides a preparation method of electrical steel and electrical steel, aiming to provide a method that can significantly improve the spot peeling phenomenon on the edge of electrical steel, improve the yield rate of electrical steel, and improve the comprehensive performance of electrical steel.

[0005] In a first aspect, embodiments of the present application provide a method for preparing electrical steel, comprising:

[0006] The tundish molten steel is continuously cast through the chamfered crystallizer at a speed of 1.2 to 1.5 m / min to obtain a continuously cast billet;

[0007] The method of continuously casting the tundish molten steel through the chamfered crystallizer at a speed of 1.2 to 1.5 m / min includes: cooling the molten steel in the chamfered crystallizer, wherein the cooling includes using first cooling water in a first direction and second cooling water in a second direction;

[0008] The flow rate of the first cooling water is 4200 L / min to 4900 L / min, and the flow rate of the second cooling water is 580 L / min to 650 L / min.

[0009] According to an embodiment of one aspect of the present application, the flow rate of the first cooling water is 8.5 m / s-9.5 m / s.

[0010] According to an embodiment of one aspect of the present application, the distance between one end of the submerged nozzle of the chamfered crystallizer immersed in the molten steel and the surface of the molten steel is 120mm-130mm.

[0011] According to an embodiment of one aspect of the present application, when the width of the electrical steel is 1220 to 1250 mm, the taper coefficient of the chamfered crystallizer is 1.4%-1.6%.

[0012] According to an embodiment of one aspect of the present application, the superheat degree of the molten steel in the tundish is 25°C to 35°C.

[0013] According to an embodiment of one aspect of the present application, the pouring temperature of the molten steel in the tundish is 1552°C to 1564°C.

[0014] According to an embodiment of one aspect of the present application, the tundish molten steel includes, in mass percentage, the following: C≤0.0025%, Si: 1.2%-1.5%, Mn: 0.25%-0.35%, Al: 0.2%-0.3%, and the remainder is iron and unavoidable impurity elements.

[0015] According to an embodiment of one aspect of the present application, the liquidus temperature of the molten steel in the tundish is 1527°C to 1529°C.

[0016] According to an embodiment of one aspect of the present application, the method also includes: slab heating, high-pressure water dephosphorization, hot rolling, laminar cooling, coiling and packaging into a furnace, the slab heating temperature is 1150±20°C, the slab heating time is 110-130min, and the slab heated out-of-furnace temperature is 1030-1070°C; hot rolling includes finishing rolling, and the final rolling temperature of finishing rolling is 900±15°C.

[0017] In a second aspect, an embodiment of the present application provides an electrical steel produced by the preparation method of the first aspect.

[0018] This application has at least the following beneficial effects:

[0019] The method provided in the present application, under a suitable continuous casting speed and in combination with a suitable cooling water flow rate, can promote the rapid solidification of molten steel on the meniscus of the chamfered crystallizer during the preparation process of electrical steel, ensure sufficient strength of the solidified billet shell, avoid the leakage of molten steel causing small steel particles on the chamfered edge of the electrical steel and point-like peeling during the hot rolling process, thereby reducing the occurrence of point-like peeling on the edge of the electrical steel, improving the quality of the edge of the electrical steel and improving the yield rate of the electrical steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the implementation regulations of this application, the following is a brief introduction to the drawings required for use in the embodiments of this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0021] Figure 1 A schematic diagram of the structure of molten steel and protective slag in a chamfered crystallizer according to an embodiment of the present application is shown.

[0022] Figure 2 The figure shows the appearance of peeling at the chamfer of the electrical steel billet of comparative example 1 of the present application.

[0023] Figure 3 The figure shows the appearance of the chamfered corner of the electrical steel billet of Example 1 of the present application.

[0024] Among them, 1. Chamfered crystallizer; 2. Glass slag layer; 3. Crystallization slag layer; 4. Liquid slag layer; 5. Solidified shell; 6. Immersed nozzle. DETAILED DESCRIPTION

[0025] In order to make the application purpose, technical solutions and beneficial technical effects of this application clearer, the application is further described in detail below with reference to the embodiments. It should be understood that the implementation regulations described in this specification are only for the purpose of explaining this application and are not intended to limit this application.

[0026] For simplicity, this application only explicitly discloses certain numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and similarly, any upper limit can be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value can serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0027] In the description of this application, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number, and “a variety” in “one or more” means two or more.

[0028] The above disclosure of the present application is not intended to describe every disclosed embodiment or every implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided through a series of examples, and these implementation regulations can be used in various combinations. In each example, the enumeration is only intended to be representative and should not be construed as exhaustive.

[0029] During the solidification and forming process of molten steel, the connection between the wide surface and the chamfered surface of the crystallizer is often insufficient due to factors such as excessive corner gap, weak cooling water volume of the crystallizer, and unreasonable setting of the crystallizer taper. This often leads to quality problems such as small steel particles or infiltration of steel (see the figure below). When the amount of infiltration is serious or the amount of burn-in in the heating furnace is small, edge defects such as edge scarring and spot peeling will appear during the hot rolling process. The product quality does not meet the judgment requirements, and the edge trimming is outsourced, resulting in certain economic losses and seriously affecting the fulfillment of product orders.

[0030] In view of this, an embodiment of the present application provides a method for preparing electrical steel to solve the above problems.

[0031] Method for preparing electrical steel

[0032] In a first aspect, embodiments of the present application provide a method for preparing electrical steel, comprising:

[0033] The tundish molten steel is continuously cast through the chamfered crystallizer at a speed of 1.2 to 1.5 m / min to obtain a continuously cast billet;

[0034] The method of continuously casting the tundish molten steel through the chamfered crystallizer at a speed of 1.2 to 1.5 m / min includes: cooling the molten steel in the chamfered crystallizer, wherein the cooling includes using first cooling water in a first direction and second cooling water in a second direction;

[0035] The flow rate of the first cooling water is 4200 L / min to 4900 L / min, and the flow rate of the second cooling water is 580 L / min to 650 L / min.

[0036] Optionally, the tundish molten steel is continuously cast through the chamfered mold at a speed of 1.20 m / min, 1.25 m / min, 1.30 m / min, 1.35 m / min, 1.40 m / min, 1.45 m / min, or 1.50 m / min. This speed can be understood as the casting speed of the continuous casting.

[0037] Optionally, the flow rate of the first cooling water can be any value among 4200L / min, 4250L / min, 4300L / min, 4350L / min, 4400L / min, 4450L / min, 4500L / min, 4550L / min, 4600L / min, 4650L / min, 4700L / min, 4750L / min, 4800L / min, 4850L / min, 4900L / min or any range of their combinations.

[0038] Optionally, the flow rate of the first cooling water can be any value among 580L / min, 590L / min, 600L / min, 610L / min, 620L / min, 630L / min, 640L / min, 650L / min or a range thereof.

[0039] It can be understood that the first direction may be the wide direction of the crystallizer or the length direction of the continuous casting billet; the second direction may be the narrow direction of the crystallizer or the width direction of the continuous casting billet.

[0040] In the embodiment of the present application, the molten steel in the middle package is continuously cast through the chamfered crystallizer at a speed of 1.2 to 1.5 m / min. Combined with an appropriate cooling water flow rate, the rapid solidification of the molten steel on the meniscus of the chamfered crystallizer can be promoted, sufficient strength of the solidified billet shell can be ensured, and the leakage of molten steel can be avoided, thereby improving the apparent quality of the corner area of ​​the chamfered continuous casting billet of electrical steel, reducing the rework rate of its hot-rolled coil, improving the overall yield rate, and saving production costs.

[0041] In addition, the first cooling water flow in the first direction is greater than the second cooling water flow in the second direction, which can further increase the shrinkage of the solidified shell, especially the shrinkage of the initial solidified shell in the meniscus area, thereby enhancing the strength of the solidified shell and preventing the leakage of molten steel.

[0042] In some optional embodiments, the flow rate of the first cooling water is 8.5 m / s-9.5 m / s. The flow rate of the first cooling water within the above range, matched with the flow rate of the first cooling water, can promote rapid solidification of the molten steel at the chamfered meniscus of the crystallizer, ensure sufficient solidified shell strength, further improve the surface quality of the corner area of ​​the electrical steel continuous casting slab, and further reduce the repair rate.

[0043] In some optional embodiments, the distance between one end of the submerged nozzle of the chamfered crystallizer immersed in the molten steel and the surface of the molten steel is 120mm-130mm. The distance between one end of the submerged nozzle immersed in the molten steel and the surface of the molten steel can be understood as the insertion depth of the submerged nozzle. Within the above range, the overall heat of the molten steel reflow zone in the chamfered crystallizer can be moved upward, effectively promoting the melting of the protective slag, improving the solidification heat conductivity, facilitating the rapid formation or thickening of the solidified shell, and enhancing the strength of the solidified shell, reducing molten steel seepage, thereby improving the apparent quality of the corner area of ​​the electrical steel continuous casting billet, reducing the rework rate, improving the overall yield rate, and saving production costs.

[0044] In addition, the distance between one end of the submerged nozzle immersed in the molten steel and the surface of the molten steel is within the above range, which will not obviously cause the risk of slag rolling in the crystallizer protective slag, and can make the flow rate of the molten steel surface in the crystallizer within a reasonable range, which is conducive to normal continuous casting.

[0045] In some optional embodiments, when the width of the electrical steel is 1220 to 1250 mm, the taper coefficient of the chamfered crystallizer is 1.4%-1.6%.

[0046] It can be understood that: mold taper coefficient = mold taper / steel width

[0047] The taper coefficient of the chamfered crystallizer is within the above range, which can provide sufficient support to avoid the phenomenon of insufficient support force of the solidified shell on the narrow side of the crystallizer, thereby preventing the loss of support and leakage of molten steel after the solidified shell shrinks, improving the apparent quality of the corner area of ​​the electrical steel continuous casting billet, reducing the rework rate, improving the comprehensive yield rate, and saving production costs.

[0048] In some optional embodiments, the superheat of the molten steel in the tundish is between 25° C. and 35° C. Controlling the superheat of the molten steel in the tundish within the above range is conducive to promoting the rapid melting of the mold powder in the crystallizer, improving lubrication, and allowing the liquid mold powder to flow between the solidified shell and the crystallization wall. This improves the heat conduction effect compared to air heat conduction, facilitates the rapid formation or thickening of the solidified shell, enhances the strength of the solidified shell, reduces molten steel seepage, thereby improving the apparent quality of the corner area of ​​the electrical steel continuous casting slab, reducing the rework rate, increasing the overall yield rate, and saving production costs.

[0049] Figure 1 The schematic diagram of the structure of molten steel and protective slag in the chamfered crystallizer of the embodiment of the present application is shown. Figure 1 Molten steel is contained in a chamfered mold 1. Within the container wall of the chamfered mold 1 are, in order, a glass slag layer 2 and a crystallized slag layer 3. The molten steel between the molten steel and the crystallized slag layer 3 begins to cool, forming a solidified shell 5. The mold slag liquefies under the action of high temperature, becoming liquefied mold slag. The liquefied mold slag flows between the solidified shell 5 and the crystallized slag layer 3, forming a liquid slag layer 4. This also facilitates the formation of the solidified shell 5 and enhances its strength. The molten steel enters the chamfered mold 1 through a submerged nozzle 6.

[0050] In some optional embodiments, the pouring temperature of the tundish steel is 1552° C. to 1564° C. The pouring temperature of the tundish steel within the above range can promote rapid melting of the mold powder in the crystallizer, improve lubrication, facilitate rapid formation or thickening of the solidified shell, enhance the strength of the solidified shell, and reduce molten steel seepage.

[0051] In some optional embodiments, the tundish molten steel comprises, by mass percentage, the following: C ≤ 0.0025%, Si: 1.2%-1.5%, Mn: 0.25%-0.35%, Al: 0.2%-0.3%, with the remainder being iron and unavoidable impurities. Tundish molten steel with this composition is susceptible to edge flaking during hot rolling. The above method can improve this edge flaking in hot-rolled electrical steel.

[0052] The liquidus temperature of the tundish molten steel of this composition is within a certain range, and the superheat of the tundish molten steel can be controlled, thereby achieving the purpose of reducing the seepage of the molten steel.

[0053] In some optional embodiments, the liquidus temperature of the molten steel in the tundish is 1527° C. to 1529° C. When the liquidus temperature of the molten steel in the tundish is within the above range, the casting temperature can be controlled, thereby reducing molten steel seepage during the continuous casting process and improving the surface quality of the continuously cast slab.

[0054] In some optional embodiments, the method also includes: slab heating, high-pressure water dephosphorization, hot rolling, laminar cooling, coiling and packaging into the furnace, the slab heating temperature is 1150±20℃, the slab heating time is 110-130min, and the slab out-of-furnace temperature is 1030-1070℃; hot rolling includes finishing rolling, and the final rolling temperature of finishing rolling is 900±15℃.

[0055] In some optional embodiments, the coiling temperature is 725±18°C

[0056] In a second aspect, embodiments of the present application provide an electrical steel produced by the preparation method of the first aspect. The electrical steel produced by the above method has good edge quality, especially good edge quality at the chamfer, which improves and enhances the surface quality of the continuous casting billet and the electrical steel after hot rolling.

[0057] Example

[0058] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and all instruments used in the examples are commercially available.

[0059] Example 1

[0060] This embodiment provides a method for preparing electrical steel, comprising the following steps:

[0061] Continuously casting the tundish molten steel through a chamfered crystallizer at a speed of 1.3 m / min to obtain a continuously cast billet, wherein the tundish molten steel comprises, by mass percentage, the following: C ≤ 0.0025%, Si: 1.3%, Mn: 0.30%, Al: 0.25%, and the balance being iron and unavoidable impurity elements;

[0062] The method of continuously casting the tundish molten steel through the chamfered crystallizer at a speed of 1.3 m / min includes: cooling the molten steel in the chamfered crystallizer, wherein the cooling includes using first cooling water in a first direction and second cooling water in a second direction;

[0063] The primary cooling water flow rate is 4200 L / min, with a primary cooling water velocity of 8.91 m / s; the secondary cooling water flow rate is 610 L / min. The immersion nozzle insertion depth is 120 mm. The width of the electrical steel is 1230 mm, and the chamfered mold taper coefficient is 1.5%. The superheat of the molten steel in the tundish is 31°C, the pouring temperature of the molten steel in the tundish is 1552°C, and the liquidus temperature of the molten steel in the tundish is 1521°C.

[0064] The continuously cast slab then undergoes slab heating, high-pressure water dephosphorization, hot rolling, laminar cooling, coiling, and packaging for loading into a furnace to produce electrical steel. The slab heating temperature is 1150±20°C for 110-130 minutes, and the slab exits the furnace at a temperature of 1030-1070°C. Hot rolling includes finishing rolling, with the final rolling temperature at 900±15°C.

[0065] Example 2

[0066] The difference between this embodiment and embodiment 1 is that the flow rate of the first cooling water is 4900 L / min and the flow rate of the second cooling water is 650 L / min.

[0067] Example 3

[0068] The difference between this embodiment and embodiment 1 is that the flow rate of the first cooling water is 4600 L / min, the flow velocity of the first cooling water is 8.93 m / s; the flow rate of the second cooling water is 580 L / min.

[0069] Example 4

[0070] The difference between this embodiment and embodiment 1 is that the taper coefficient of the chamfered crystallizer is 1.6%.

[0071] Example 5

[0072] The difference between this embodiment and embodiment 1 is that the superheat of the molten steel in the middle ladle is 35°C, the pouring temperature of the molten steel in the middle ladle is 1556°C, and the liquidus temperature of the molten steel in the middle ladle is 1521°C.

[0073] Example 6

[0074] The difference between this embodiment and embodiment 1 is that the insertion depth of the submerged nozzle is increased from the previous 155 mm.

[0075] Example 7

[0076] The difference between this embodiment and embodiment 1 is that the taper coefficient of the chamfered crystallizer is 1.3%.

[0077] Example 8

[0078] The difference between this embodiment and embodiment 1 is that the superheat of the molten steel in the middle ladle is 20°C, the pouring temperature of the molten steel in the middle ladle is 1541°C, and the liquidus temperature of the molten steel in the middle ladle is 1521°C.

[0079] Comparative Example 1

[0080] The difference between this comparative example and Example 1 is that the tundish molten steel is continuously cast through the chamfered crystallizer at a speed of 1.8 m / min.

[0081] Comparative Example 2

[0082] The difference between this comparative example and Example 1 is that the flow rate of the first cooling water on the narrow side of the chamfered crystallizer is 7.60 m / s, and the flow rate of the first cooling water is 3580 L / min.

[0083] Test section

[0084] The electrical steel coils prepared in the examples and comparative examples were tested for peeling at the edges, and the peeled portions of the coils were trimmed. The peeled portions of the coils were generally located 35-45 mm in the wide width direction of the coils. The coils with peeled edges were trimmed, and the remaining coils were unqualified.

[0085] Trimming rate = the mass of the peeled steel coil that has been trimmed / the mass of the steel coil that has not been trimmed

[0086] Yield rate = quality of qualified steel coils / quality of untrimmed steel coils

[0087] Table 1 Test results of electrical steel of Examples and Comparative Examples.

[0088]

[0089]

[0090] The above measured performance parameters are averaged.

[0091] The spot peeling phenomenon at the chamfer of the chamfered electrical steel in Comparative Example 1 is as follows Figure 2 As shown; in Example 1, the chamfered electrical steel has less spot peeling at the chamfer, such as Figure 3 shown. Figure 2 and Figure 3 The comparison shows that the method of the embodiment of the present application can effectively reduce the spot peeling at the chamfer of chamfered electrical steel and improve the surface quality of the electrical steel.

[0092] The above are only specific embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any familiarity with the present technology or replacement should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for preparing electrical steel, characterized in that: include: The tundish molten steel is continuously cast through the chamfered crystallizer at a speed of 1.2-1.5 m / min to obtain a continuous casting billet; The method of continuously casting the tundish molten steel through the chamfered crystallizer at a speed of 1.2 to 1.5 m / min includes: cooling the molten steel in the chamfered crystallizer, wherein the cooling includes using first cooling water in a first direction and second cooling water in a second direction; the first direction is the wide side direction of the chamfered crystallizer; and the second direction is the narrow side direction of the chamfered crystallizer. The flow rate of the first cooling water is 4200 L / min to 4900 L / min, and the flow rate of the second cooling water is 580 L / min to 650 L / min.

2. The preparation method according to claim 1, characterized in that The flow rate of the first cooling water is 8.5m / s-9.5m / s.

3. The preparation method according to claim 1, characterized in that The distance between one end of the submerged nozzle of the chamfered crystallizer immersed in the molten steel and the surface of the molten steel is 120 mm to 130 mm.

4. The preparation method according to claim 1, characterized in that When the width of the electrical steel is 1220 to 1250 mm, the taper coefficient of the chamfered crystallizer is 1.4% to 1.6%.

5. The preparation method according to claim 1, characterized in that The superheat degree of the molten steel in the tundish is 25°C to 35°C.

6. The preparation method according to claim 1, characterized in that The pouring temperature of the tundish molten steel is 1552°C to 1564°C.

7. The preparation method according to claim 1, characterized in that The tundish molten steel comprises, by mass percentage, the following: C≤0.0025%, Si: 1.2%-1.5%, Mn: 0.25%-0.35%, Al: 0.2%-0.3%, and the remainder being iron and unavoidable impurity elements.

8. The preparation method according to claim 1, characterized in that The liquidus temperature of the tundish molten steel is 1527°C to 1529°C.

9. The preparation method according to any one of claims 1 to 8, characterized in that The method also includes: slab heating, high-pressure water dephosphorization, hot rolling, laminar cooling, coiling and packaging into a furnace, the slab heating temperature is 1150±20°C, the slab heating time is 110-130 minutes, and the slab out-of-furnace temperature is 1030-1070°C; the hot rolling includes finish rolling, and the final rolling temperature of the finish rolling is 900±15°C.

10. An electrical steel, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 9.

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