A method for controlling grain boundary defects of grain-oriented silicon steel

Abstract

The application relates to a method for controlling edge grain defect of oriented silicon steel, characterized in that the method comprises the following steps: coating a set amount of grain defect control slurry in a set range of the inner ring and / or the outer ring of the upper end face and / or the lower end face of an oriented silicon steel coil to reduce the edge grain defect occurrence rate of the oriented silicon steel; and covering the whole end face of the upper end of the steel coil with a metal cover plate on the upper end cover of the steel coil. The method coats the grain defect control slurry in a certain area of the upper and / or lower end face of the steel coil, so that the grain defect control slurry can increase the local interlayer oxidation of the strip steel at high temperature, and then increase the bottom layer reaction, so as to control the width and length of the edge grain defect.

Description

Technical Field

[0001] This application relates to the field of grain-oriented silicon steel manufacturing, and more particularly to a method for controlling edge crystallization defects in grain-oriented silicon steel. Background Technology

[0002] Grain-oriented silicon steel is an important soft magnetic material in power construction, hailed as the "crown jewel" of the steel industry, and is widely used in transformer manufacturing. Transformer manufacturing and use require grain-oriented silicon steel to possess characteristics such as "low iron loss, high magnetic induction, excellent surface quality, and superior plate shape."

[0003] Crystallization defects are a common and typical surface defect in grain-oriented silicon steel products, affecting their application. To control crystallization defects caused by poor reaction, methods such as adjusting the steel composition, adjusting the oxide film structure during decarburization annealing, improving the activity of the MgO release agent, and optimizing the high-temperature annealing process are generally employed. However, traditional methods have consistently failed to effectively control edge-point crystallization defects. Summary of the Invention

[0004] This application provides a method for controlling edge crystallization defects in grain-oriented silicon steel, thereby solving the technical problem that the existing technology has poor improvement effect on edge crystallization of grain-oriented silicon steel.

[0005] In a first aspect, this application provides a method for controlling edge crystallization defects in grain-oriented silicon steel, the method comprising:

[0006] Apply a set amount of crystallization defect control slurry to the inner and / or outer rings of the upper and / or lower end faces of the grain-oriented silicon steel coil to reduce the crystallization rate at the edges of the grain-oriented silicon steel.

[0007] A metal cover plate is placed over the upper end of the steel coil, covering the entire upper end face of the steel coil.

[0008] Furthermore, when the set range is the lower end face of the steel coil or the entire lower end face, the set amount of the crystallization defect control slurry is 500g to 10kg; and / or

[0009] When the set range is 50mm to 600mm from the lower end face or the outer circumference of the lower end face of the steel coil, the set amount of the crystallization defect control slurry is 100g to 8kg; and / or

[0010] When the set range is 50mm to 600mm from the lower end face or the inner circle of the lower end face of the steel coil, the set amount of the crystallization defect control slurry is 100g to 6kg.

[0011] Furthermore, the crystallization defect control slurry comprises the following components: halide salts and / or oxyacid salts, and solvents.

[0012] Furthermore, the crystallization defect control slurry also includes an adhesive.

[0013] Furthermore, the adhesive includes at least one of methylcellulose, hydroxypropylcellulose, and hydroxyethylcellulose.

[0014] Furthermore, the crystallization defect control slurry also includes a carrier substance.

[0015] Furthermore, the carrier material includes at least one of MgO and Al2O3.

[0016] Furthermore, the mass ratio of the halide, oxyacid salt, binder and carrier substance is 0.3-5:0.5-10:0.1-0.5:10-50.

[0017] Furthermore, the crystallization defect control slurry is uniformly distributed on the surface of the steel coil.

[0018] Furthermore, the thickness of the metal cover plate is 0.1 to 1 mm.

[0019] The technical solutions provided in this application have the following advantages compared with the prior art:

[0020] This application provides a method for controlling edge crystallization defects in grain-oriented silicon steel. The method includes: applying a predetermined amount of crystallization defect control slurry within a set range of the inner and / or outer rings of the upper and / or lower end faces of the grain-oriented silicon steel coil to reduce the occurrence rate of edge crystallization. This method, by applying the crystallization defect control slurry to a certain area on the upper and / or lower end faces of the steel coil, allows the slurry to increase the local interlayer oxidation of the strip at high temperatures, thereby increasing the reaction in the underlying layer and achieving the purpose of controlling the width and length of edge crystallization. A metal cover plate allows the gas generated by the crystallization defect control slurry at high temperatures to enter the local interlayer of the strip, preventing it from escaping. Therefore, this method can effectively prevent the formation of crystallization defects and solves the technical problem of poor improvement effect of existing technologies on edge crystallization of grain-oriented silicon steel. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1The oriented silicon steel in this embodiment is rolled into a coil after decarburization annealing, wherein 1 is a steel coil and 2 is a sleeve;

[0024] Figure 2 The above refers to the oriented silicon steel coiled into a roll after decarburization annealing in the embodiments of this application, wherein 1 is the outer ring of the steel coil sprayed with slurry, and 2 is the inner ring of the steel coil sprayed with slurry.

[0025] Figure 3 The deformation state of the steel coil during the high-temperature annealing process is shown in Figure 1, where 1 is the undeformed steel coil at low temperature and 2 is the steel coil deformed by high temperature during the high-temperature annealing process.

[0026] Figure 4 The method for controlling edge crystallization defects in oriented silicon steel provided in this application improves the crystallization state of the front and rear edges of the strip, wherein 1 is the crystallization zone and 2 is the normal magnesium silicate bottom layer zone. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0029] Grain-oriented silicon steel is an important soft magnetic material in power construction, hailed as the "crown jewel" of the steel industry, and is widely used in transformer manufacturing. Transformer manufacturing and use require grain-oriented silicon steel to possess characteristics such as "low iron loss, high magnetic induction, excellent surface quality, and superior plate shape."

[0030] Crystallization defects are a common and typical surface defect in grain-oriented silicon steel products, affecting their application. To control crystallization defects caused by poor reaction, methods such as adjusting the steel composition, adjusting the oxide film structure during decarburization annealing, improving the activity of the MgO release agent, and optimizing the high-temperature annealing process are generally employed. However, traditional methods have consistently failed to effectively control edge-point crystallization defects.

[0031] The technical solution provided by the embodiments of the present invention is to solve the above-mentioned technical problems, and the general idea is as follows:

[0032] In a first aspect, this application provides a method for controlling edge crystallization defects in grain-oriented silicon steel, the method comprising:

[0033] A predetermined amount of crystallization defect control slurry is applied to the inner and / or outer rings of the upper and / or lower end faces of the grain-oriented silicon steel coil to reduce the crystallization rate at the edges of the grain-oriented silicon steel; a metal cover plate is placed on the upper end of the coil, the cover plate covering the entire end face of the upper end of the coil.

[0034] This application provides a method for controlling edge crystallization defects in grain-oriented silicon steel. The method includes: applying a predetermined amount of crystallization defect control slurry within a set range of the inner and / or outer rings of the upper and / or lower end faces of the grain-oriented silicon steel coil to reduce the occurrence rate of edge crystallization. This method, by applying the crystallization defect control slurry to a certain area on the upper and / or lower end faces of the steel coil, allows the slurry to increase the local interlayer oxidation of the strip at high temperatures, thereby increasing the reaction in the underlying layer and achieving the purpose of controlling the width and length of edge crystallization. A metal cover plate allows the gas generated by the crystallization defect control slurry at high temperatures to enter the local interlayer of the strip, preventing it from escaping. Therefore, this method can effectively prevent the formation of crystallization defects and solves the technical problem of poor improvement effect of existing technologies on edge crystallization of grain-oriented silicon steel.

[0035] In this application, the spraying method for the crystal defect control slurry can be mechanical spraying or brushing, or manual spraying or brushing.

[0036] In one embodiment of the present invention, when the set range is the lower end face of the steel coil or the entire lower end face, the set amount of the crystallization defect control slurry is 500g to 10kg; and / or

[0037] When the set range is 50mm to 600mm from the lower end face or the outer circumference of the lower end face of the steel coil, the set amount of the crystallization defect control slurry is 100g to 8kg; and / or

[0038] When the set range is 50mm to 600mm from the lower end face or the inner circle of the lower end face of the steel coil, the set amount of the crystallization defect control slurry is 100g to 6kg.

[0039] In this application, by controlling the coating area and amount of the crystallization defect control slurry, the width and length of edge crystallization can be effectively reduced. The spraying range of the crystallization defect control slurry can be set according to requirements. If the amount of crystallization defect control slurry applied is too small, the reduction effect will be achieved; if the amount applied is too large, blocky crystallization defects will be generated.

[0040] As one embodiment of the present invention, the crystallization defect control slurry includes the following components: halide salts and / or oxyacid salts, and solvents.

[0041] In this application, oxyacid salts refer to salts containing oxygen, including NaNO3, MgSO4, KClO4, etc. In this application, halide salts refer to metal halides, including NaI, MgCl2, CaCl2, NaF, etc. The formation of crystallization defects mainly occurs during the high-temperature annealing stage. The outer ring of the steel coil expands, increasing the interlayer spacing. H2 in the annealing atmosphere easily enters the interlayer. Fe2SiO4 generated on the strip surface during the decarburization annealing stage is reduced by H2, resulting in Fe2SiO4 + H2 → SiO2 + Fe + H2O. The formed H2O escapes along the interlayer gap to the outside of the steel coil, while the amount of Fe2SiO4 decreases, leading to reduced bottom-layer reactivity and making crystallization defects more likely. Oxyacid salts can decompose at high temperatures, releasing O2 to replenish interlayer oxidizing properties and prevent reduced bottom-layer reactivity, thus avoiding crystallization defects. Halides can generate acids at high temperatures, which can corrode the strip surface and promote bottom-layer formation reactions. Therefore, controlling the crystallization defect slurry can increase the bottom-layer reaction, thereby preventing the formation of crystallization defects.

[0042] As one embodiment of the present invention, the crystallization defect control slurry further includes an adhesive.

[0043] In this application, the binder is beneficial to the film-forming and moisture-retaining properties of the slurry. The binder is an organic substance with a certain viscosity and moisturizing effect.

[0044] As one embodiment of the present invention, the adhesive includes at least one of methylcellulose, hydroxypropylcellulose, and hydroxyethylcellulose.

[0045] As one embodiment of the present invention, the crystallization defect control slurry also includes a carrier substance.

[0046] In this application, the carrier material makes the crystallization defect control slurry easier to apply.

[0047] In one embodiment of the present invention, the carrier material includes at least one of MgO and Al2O3.

[0048] In one embodiment of the present invention, the mass ratio of the halide, oxyacid salt, binder and carrier substance is 0.3-5:0.5-10:0.1-0.5:10-50.

[0049] In this application, the mass ratio is obtained through experiments. By adjusting the mass ratio of each component, the effect of controlling crystallization defects in the slurry is improved.

[0050] In one embodiment of the present invention, the crystallization defect control slurry is uniformly distributed on the surface of the steel coil.

[0051] In this application, the crystallization defect control slurry is evenly distributed on the surface of the steel coil, which can avoid the situation where some areas have insufficient coating and poor effect, while other areas have excessive coating and blocky crystallization defects.

[0052] In one embodiment of the present invention, the thickness of the metal cover plate is 0.1 to 1 mm.

[0053] In this application, the thickness of the metal cover plate is set to 0.1 to 1 mm, which allows the metal cover plate to deform at high temperatures, thereby better fitting with the upper surface of the grain-oriented silicon steel coil.

[0054] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0055] Example 1

[0056] A method for controlling edge crystallization defects in grain-oriented silicon steel, characterized by the following steps:

[0057] (1) Preparation of crystallization defect control slurry: Take 2 parts MgCl2, 0.2 parts methylcellulose, 50 parts MgO and 47.8 parts water, mix them evenly to obtain crystallization defect control slurry;

[0058] (2) Preparation of grain-oriented silicon steel:

[0059] The cold-rolled grain-oriented silicon steel sheet is decarburized and annealed (including nitriding), coated with a magnesium oxide release agent, and then rolled into coils to obtain steel coils, such as... Figure 1 As shown;

[0060] Spray 3 kg of crystallization defect control slurry within a 150 mm width area around the upper and lower ends of the steel coil. Figure 2 As shown;

[0061] A 0.5mm thick metal cover plate is placed over the top of the steel coil, covering the entire end face of the top of the steel coil.

[0062] The coated steel coils are then sent into a ring furnace for high-temperature annealing.

[0063] After high-temperature annealing, the steel coils are subjected to hot stretching and leveling processes and rewinding and edge trimming to remove the exposed crystal areas on the edges, resulting in oriented silicon steel with good surface finish.

[0064] Example 2

[0065] A method for controlling edge crystallization defects in grain-oriented silicon steel, characterized by the following steps:

[0066] (1) Preparation of crystallization defect control slurry: Take 5 parts of MgSO4, 0.3 parts of methylcellulose, 40 parts of MgO and 54.7 parts of water, mix them evenly to obtain crystallization defect control slurry;

[0067] (2) Preparation of grain-oriented silicon steel:

[0068] The cold-rolled grain-oriented silicon steel sheet is decarburized and annealed (including nitriding), coated with a magnesium oxide release agent, and then rolled into coils to obtain steel coils, such as... Figure 1 As shown;

[0069] Spray 5 kg of crystallization defect control slurry within a 300 mm width area around the upper and lower ends of the steel coil. Figure 2 As shown;

[0070] A 0.1mm thick metal cover plate is placed over the top of the steel coil, covering the entire end face of the top of the steel coil;

[0071] The coated steel coils are then sent into a ring furnace for high-temperature annealing.

[0072] After high-temperature annealing, the steel coils are subjected to hot stretching and leveling processes and rewinding and edge trimming to remove the exposed crystal areas on the edges, resulting in oriented silicon steel with good surface finish.

[0073] Example 3

[0074] A method for controlling edge crystallization defects in grain-oriented silicon steel, characterized by the following steps:

[0075] (1) Preparation of crystallization defect control slurry: Take 1 part CaCl2, 3 parts NaNO3, 0.3 parts methylcellulose, 10 parts MgO and 85.7 parts water, mix them evenly to obtain crystallization defect control slurry;

[0076] (2) Preparation of grain-oriented silicon steel:

[0077] The cold-rolled grain-oriented silicon steel sheet is decarburized and annealed (including nitriding), coated with a magnesium oxide release agent, and then rolled into coils to obtain steel coils, such as... Figure 1 As shown;

[0078] Spray 8 kg of crystallization defect control slurry onto the entire end face of the upper part of the steel coil, such as... Figure 2 As shown;

[0079] Cover the top of the steel coil with a 1mm thick metal cover plate, covering the entire end face of the top of the steel coil;

[0080] The coated steel coils are then sent into a ring furnace for high-temperature annealing.

[0081] After high-temperature annealing, the steel coils are subjected to hot stretching and leveling processes and rewinding and edge trimming to remove the exposed crystal areas on the edges, resulting in oriented silicon steel with good surface finish.

[0082] Example 4

[0083] A method for controlling edge crystallization defects in grain-oriented silicon steel, characterized by the following steps:

[0084] (1) Preparation of crystallization defect control slurry: Take 5 parts NaCl and 90 parts water, mix them evenly to obtain crystallization defect control slurry;

[0085] (2) Preparation of grain-oriented silicon steel:

[0086] The cold-rolled grain-oriented silicon steel sheet is decarburized and annealed (including nitriding), coated with a magnesium oxide release agent, and then rolled into coils to obtain steel coils, such as... Figure 1 As shown;

[0087] Spray 4 kg of crystallization defect control slurry within a 200 mm width area around the upper and lower ends of the steel coil. Figure 2 As shown;

[0088] A 0.8mm thick metal cover plate is placed over the top of the steel coil, covering the entire end face of the top of the steel coil;

[0089] The coated steel coils are then sent into a ring furnace for high-temperature annealing.

[0090] After high-temperature annealing, the steel coils are subjected to hot stretching and leveling processes and rewinding and edge trimming to remove the exposed crystal areas on the edges, resulting in oriented silicon steel with good surface finish.

[0091] Example 5

[0092] A method for controlling edge crystallization defects in grain-oriented silicon steel, characterized by the following steps:

[0093] (1) Preparation of crystallization defect control slurry: Take 7 parts of MgSO4 and 93 parts of water, mix them evenly to obtain crystallization defect control slurry;

[0094] (2) Preparation of grain-oriented silicon steel:

[0095] The cold-rolled grain-oriented silicon steel sheet is decarburized and annealed (including nitriding), coated with a magnesium oxide release agent, and then rolled into coils to obtain steel coils, such as... Figure 1 As shown;

[0096] Spray 5 kg of crystallization defect control slurry within a 300 mm width area around the upper and lower ends of the steel coil. Figure 2 As shown;

[0097] A 0.3mm thick metal cover plate is placed over the top of the steel coil, covering the entire end face of the top of the steel coil;

[0098] The coated steel coils are then sent into a ring furnace for high-temperature annealing.

[0099] After high-temperature annealing, the steel coils are subjected to hot stretching and leveling processes and rewinding and edge trimming to remove the exposed crystal areas on the edges, resulting in oriented silicon steel with good surface finish.

[0100] Comparative Example 1

[0101] The crystallization defect control slurry in Example 4 was changed to 0.1 parts MgCl2 and 99.9 parts water, the coating range was changed to the outer 30mm width range of the upper and lower ends of the steel coil, the coating amount was changed to 300g, and the rest was the same as in Example 4.

[0102] Comparative Example 2

[0103] The crystallization defect control slurry in Example 5 was changed to 15 parts CaCl2 and 85 parts water, and the coating amount was changed to 4 kg. The rest was the same as in Example 5.

[0104] Comparative Example 3

[0105] The crystallization defect control slurry in Example 5 was changed to 0.5 parts MgSO4 and 99.8 parts water, and the coating amount was changed to 4 kg. The rest was the same as in Example 5.

[0106] Comparative Example 4

[0107] The crystallization defect control slurry in Example 5 was changed to 12 parts MgSO4 and 88 parts water, and the coating amount was changed to 4 kg. The rest was the same as in Example 5.

[0108] Comparative Example 5

[0109] This serves as a blank control group, without the application of the crystallization defect control slurry.

[0110] The surface quality test results of the oriented silicon steel prepared in the examples and comparative examples are shown in Table 1.

[0111] Table 1. Surface quality test results of the oriented silicon steel prepared in the examples and comparative examples.

[0112]

[0113]

[0114] Grain-oriented silicon steel needs to be rolled into coils during high-temperature annealing, such as... Figure 1 As shown, during the high-temperature annealing of the entire coil, the heating is uneven, resulting in uneven thermal expansion at different locations and uneven deformation of the steel coil. The deformation state of the steel coil at high temperature is as follows: Figure 3 As shown, the deformation of the steel coil due to thermal expansion increases the gap between the strip layers. Therefore, the strip loses water faster in areas of greater deformation, reduces interlayer oxidation, and leads to poor formation of the magnesium silicate underlayer, resulting in exposed crystal defects. Figure 3It is known that the inner and outer rings at the top and bottom of the steel coil are more susceptible to thermal deformation, leading to crystallization at the edges of the inner and outer rings of the strip. Locally generated crystallization is difficult to improve by adjusting process parameters. This invention, by coating a crystallization defect control slurry onto a certain area of ​​the steel coil and / or the lower end face, increases the local interlayer oxidation of the strip, thereby controlling the width and length of edge crystallization. The implementation of this invention can effectively reduce the width and length of edge crystallization, such as... Figure 4 As shown, even suppressing the formation of edge crystals can significantly reduce the amount of finishing edge trimming, improve the surface quality and yield of oriented silicon steel, and increase economic benefits.

[0115] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0116] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0117] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for controlling edge crystallization defects in grain-oriented silicon steel, characterized in that, The method includes: A set amount of crystallization defect control slurry is applied within a set range of the inner and / or outer rings of the upper and / or lower end faces of the grain-oriented silicon steel coil, so that the crystallization defect control slurry increases the local interlayer oxidation of the strip at high temperature to reduce the crystallization rate at the edge of the grain-oriented silicon steel. A metal cover plate is placed on the upper end of the steel coil, and the cover plate covers the entire end face of the upper end of the steel coil; When the set range is the lower end face of the steel coil or the entire lower end face, the set amount of the crystallization defect control slurry is 500g~10kg; and / or When the set range is 50mm to 600mm from the lower end face or the outer circumference of the lower end face of the steel coil, the set amount of the crystallization defect control slurry is 100g to 8kg; and / or When the set range is 50mm to 600mm from the lower end face or the inner circle of the lower end face of the steel coil, the set amount of the crystallization defect control slurry is 100g to 6kg. The crystallization defect control slurry comprises the following components: halide salts, oxyacid salts, binders, and carrier substances, wherein the mass ratio of the halide salts, oxyacid salts, binders, and carrier substances is 0.3~5:0.5~10:0.1~0.5:10~50; The thickness of the metal cover plate is 0.1~1mm.

2. The method according to claim 1, characterized in that, The crystallization defect control slurry includes a solvent.

3. The method according to claim 1, characterized in that, The adhesive includes at least one of methylcellulose, hydroxypropylcellulose, and hydroxyethylcellulose.

4. The method according to claim 1, characterized in that, The carrier material includes at least one of MgO and Al2O3.

5. The method according to claim 1, characterized in that, The crystallization defect control slurry is uniformly distributed on the surface of the steel coil.

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