A method for manufacturing oriented electrical steel with excellent surface quality

Abstract

The present invention provides a method for manufacturing oriented electrical steel with excellent surface quality, belonging to the technical field of oriented electrical steel manufacturing, the method comprising applying an isolating agent to the oriented electrical steel and then applying an additive; the chemical composition of the oriented electrical steel strip comprises: 0.0005% (weight) to 0.05% (weight) of Bi; the application of the isolating agent comprises: firstly uniformly applying the isolating agent on the surface of the strip, then dividing the surface of the strip into a plurality of coating areas along the width direction from the edge to the middle according to the distance from the edge of the strip, applying the additive to the coating area, and the coating amount of the additive in the coating area closer to the edge of the strip is greater. The method realizes differentiated adjustment of different areas by spraying the additive non-uniformly on the surface of the strip, so that the quality of the edge and the middle reaches the best state, thereby improving the surface quality of the oriented electrical steel.

Description

Technical Field

[0001] The present application relates to the technical field of oriented electrical steel manufacturing, and in particular to a method for manufacturing oriented electrical steel with excellent surface quality. Background Art

[0002] Grain-oriented silicon steel is a kind of metal functional material, which is mainly used in the power industry. Due to its high technical difficulty, long manufacturing process and strict process requirements, it is often praised as the "crown jewel" of the steel industry. Among them, bottom-free oriented electrical steel is mainly used as raw material for ultra-thin strips, and the cores of large generators and drive motors. When used as raw material for ultra-thin strips, if there is a bottom layer composed of magnesium silicate on the surface of the strip, it will aggravate the wear of the rollers during the rolling process, and cause the bottom layer and the metal substrate to peel off due to different elongation rates, affecting the rolling accuracy. The peeled bottom layer will contaminate the rolling oil system; when used as the core of large generators and drive motors, if there is a magnesium silicate bottom layer on the surface of the strip, it will greatly damage the life of the stamping mold, and the number of stamping times may be reduced from tens of thousands to thousands. Therefore, bottom-free oriented electrical steel requires that there is no bottom layer residue on the surface of the strip.

[0003] The traditional manufacturing of bottom-free oriented silicon steel adopts the technology of adjusting the release agent formula, that is, mixing the characteristic elements that cause the bottom layer to be loose into the release agent in the form of additives, and evenly applying the release agent to the surface of the strip by roller coating, so that the main area of ​​the strip can be free of bottom layers. However, during the high-temperature annealing process, the steel coil is heated unevenly, and the bottom layer reaction degree in different areas is different. Therefore, while the bottom layer is well controlled in the middle area of ​​the plate width, it is very easy to have residual bottom layer defects at the edge. To solve the problem of residual bottom layer at the edge, the traditional method is to optimize the method of adjusting the release agent formula and adjusting the ring furnace process. However, while the edge residue is alleviated, it will damage the surface quality of the middle part. Therefore, the bottom-free oriented electrical steel manufacturers can only choose to cut off the residual bottom layer area at the edge and sacrifice the yield rate to ensure the delivery quality. Summary of the invention

[0004] The embodiment of the present application provides a method for manufacturing oriented electrical steel with excellent surface quality, so as to solve the technical problems of residual bottom layer at the edge of bottom-free oriented steel processed by the existing processing method of coating isolation agent, large trimming amount and low yield rate.

[0005] In a first aspect, an embodiment of the present application provides a method for manufacturing oriented electrical steel with excellent surface quality, the method comprising applying a release agent and then applying an additive to the oriented electrical steel;

[0006] The chemical composition of the oriented electrical steel strip includes: 0.0005% (by weight) to 0.05% (by weight) Bi;

[0007] The method of applying the additive after applying the isolation agent includes: firstly uniformly applying the isolation agent on the surface of the steel strip, then dividing the surface of the steel strip along the width direction from the edge to the middle according to the distance from the edge of the steel strip, and applying the additive to the coating area, wherein the coating area closer to the edge of the steel strip has a larger amount of additive applied.

[0008] Furthermore, the coating area is divided into a first coating area, a second coating area and a third coating area, the third coating area is farther from the edge of the steel strip than the second spraying area, the second coating area is farther from the edge of the steel strip than the first coating area, the additive is uniformly coated on the surface of the steel strip in the first coating area, the additive is coated on the surface of the steel strip in the second coating area and the coating amount of the additive decreases from the outside to the inside along the width direction of the steel strip, and the additive is uniformly coated on the surface of the steel strip in the third coating area.

[0009] Further, the step of coating the additive on the surface of the steel strip in the second coating zone and the coating amount of the additive decreasing from outside to inside along the width direction of the steel strip comprises:

[0010] According to Wp and W0, the surface of the strip in the second coating zone is coated with additives in a decreasing trend from outside to inside along the width direction of the strip,

[0011] Wherein, Wp represents the distance between the coating site and the edge of the strip, and W0 represents the actual residual width of the edge of the bottom-free oriented electrical steel. Further, the strip surface of the second coating area is coated with the additive and the coating amount of the additive decreases from the outside to the inside along the width direction of the strip, including:

[0012] The additive is applied to the surface of the strip in the second coating area starting from the critical line with the first coating area and in a coating amount shown in Expression 1. The second coating area satisfies W0≤W p Area ≤W0+200;

[0013] Expression 1:

[0014]

[0015] Wherein, m represents the coating amount, Wp represents the distance between the coating site and the edge of the strip, in mm, W0 represents the actual edge residual width of the bottom-free oriented electrical steel, in mm, and m represents the coating amount, in mm. a The coating amount of the first coating area is set to 15-50g / m 2 , the m b The coating amount of the third coating area is set to 11-27 g / m 2Furthermore, the step of uniformly coating the surface of the steel strip in the first coating zone with the additive comprises:

[0016] The uniform coating mass of the strip surface in the first coating area is m a The additive, the m a Set to 15~50g / m 2 ;

[0017] Wherein, the first coating area is an area satisfying Wp<W0, the W p represents the distance between the coating position and the edge of the strip, W represents the strip width, W0 represents the actual edge residual width of the oriented electrical steel without the bottom layer, and

[0018] Furthermore, the step of uniformly coating the additive on the surface of the strip steel in the third coating zone comprises:

[0019] The uniform coating mass of the strip surface in the third coating zone is m b The additive, the m b Set to 11~27g / m 2 ; and m a >m b ;

[0020] Wherein, the third coating area satisfies The area of ​​W p represents the distance between the coating position and the edge of the strip, W represents the width of the strip, W0 represents the actual residual width of the edge of the bottom-free oriented electrical steel, and

[0021] Furthermore, the isolation agent component is a mixture of silicon steel grade MgO and Al2O3, and the mass fraction of MgO in the mixture is 20%-100%.

[0022] Furthermore, the additive is formed by mixing component A with water, and component A is at least one of NaCl, KCl, MgCl2, ZnCl2, BaCl2, SrCl2, NH4Cl, MnCl2, CaCl2, BiOCl, SbOCl, Bi(NO3)2, Cu(NO3)2, NaNO3, and NH4NO3; the concentration of the additive is 5% to 10%.

[0023] Furthermore, the droplet size of the additive coated is 10 to 300 μm.

[0024] Further, the coating of the coating area with an additive comprises:

[0025] The additive is applied to the coating area on one side and / or both sides of the surface of the steel strip.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] The embodiment of the present application provides a method for manufacturing oriented electrical steel with excellent surface quality. The method adds Bi element to the oriented silicon steel, which inhibits the formation of oxide film during decarburization annealing, and changes the morphology of SiO2 in the oxide film, so that the air permeability between steel plate layers deteriorates during high-temperature annealing. Meanwhile, during high-temperature annealing, Bi diffuses from the steel plate substrate to the external atmosphere in the form of steam bubbles. The poor air permeability between the steel plate layers makes it difficult for Bi steam to escape, which will corrode the magnesium silicate bottom layer generated on the surface of the steel plate substrate, and easily cause the interface between the steel plate substrate and the bottom layer to expand, so that the magnesium silicate bottom layer is easy to peel off during the subsequent pickling process, and after complete peeling, the bottom-free oriented silicon steel is formed; and by non-uniformly coating the additive on the strip, the coating amount at the edge is greater than that in the middle, and differentiated adjustments are achieved in different regions, so that the quality of the edge and the middle reaches the best state, thereby reducing the bottom layer residue, reducing the trimming amount, and improving the yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0030] Figure 1 A schematic diagram of a strip steel spraying device in a method for manufacturing oriented electrical steel with excellent surface quality provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of the strip spraying position and corresponding spraying amount in the method for manufacturing oriented electrical steel with excellent surface provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0033] The bottom-free oriented electrical steel is mainly used as raw material for ultra-thin strips, and the cores of large generators and drive motors. When used as raw material for ultra-thin strips, if there is a bottom layer composed of magnesium silicate on the surface of the strip, it will increase the wear of the rollers during the rolling process, and cause the bottom layer and the metal substrate to peel off due to different elongation rates, affecting the rolling accuracy. The peeled bottom layer will contaminate the rolling oil system; when used as the core of large generators and drive motors, if there is a magnesium silicate bottom layer on the surface of the strip, it will greatly damage the life of the stamping mold, and the number of stamping times may be reduced from tens of thousands to thousands. Therefore, bottom-free oriented electrical steel requires that there is no bottom layer residue on the surface of the strip.

[0034] The traditional manufacturing of bottom-free oriented silicon steel adopts the technology of adjusting the release agent formula, that is, mixing the characteristic elements that cause the bottom layer to be loose into the release agent in the form of additives, and evenly applying the release agent to the surface of the strip by roller coating, so that the main area of ​​the strip can be free of bottom layers. However, during the high-temperature annealing process, the steel coil is heated unevenly, and the bottom layer reaction degree in different areas is different. Therefore, while the bottom layer is well controlled in the middle area of ​​the plate width, it is very easy to have residual bottom layer defects at the edge. To solve the problem of residual bottom layer at the edge, the traditional method is to optimize the method of adjusting the release agent formula and adjusting the ring furnace process. However, while the edge residue is alleviated, it will damage the surface quality of the middle part. Therefore, the bottom-free oriented electrical steel manufacturers can only choose to cut off the residual bottom layer area at the edge and sacrifice the yield rate to ensure the delivery quality.

[0035] In view of this, the present application provides a method for manufacturing oriented electrical steel with excellent surface quality, which can effectively solve the above-mentioned problems existing in the existing bottom layer-free optimization method.

[0036] The technical solution provided by the embodiment of the present invention is to solve the above technical problems, and the overall idea is as follows:

[0037] The embodiment of the present application provides a method for manufacturing oriented electrical steel with excellent surface quality, so as to solve the technical problems of residual bottom layer at the edge of bottom-free oriented steel processed by existing processing methods, large trimming amount and low yield rate.

[0038] In a first aspect, an embodiment of the present application provides a method for manufacturing oriented electrical steel with excellent surface quality, wherein the method applies a release agent to the oriented electrical steel and then applies an additive;

[0039] The chemical composition of the oriented electrical steel strip includes: 0.0005% (by weight) to 0.05% (by weight) Bi;

[0040] The method of applying the additive after applying the isolation agent includes: firstly uniformly applying the isolation agent on the surface of the steel strip, then dividing the surface of the steel strip along the width direction from the edge to the middle according to the distance from the edge of the steel strip, and applying the additive to the coating area, wherein the coating area closer to the edge of the steel strip has a larger amount of additive applied.

[0041] The embodiment of the present application provides a method for manufacturing oriented electrical steel with excellent surface quality. The method adds Bi element to the oriented silicon steel, which inhibits the formation of oxide film during decarburization annealing, and changes the morphology of SiO2 in the oxide film, so that the air permeability between steel plate layers deteriorates during high-temperature annealing. Meanwhile, during high-temperature annealing, Bi diffuses from the steel plate substrate to the external atmosphere in the form of steam bubbles. The poor air permeability between the steel plate layers makes it difficult for Bi steam to escape, which will corrode the magnesium silicate bottom layer generated on the surface of the steel plate substrate, and easily cause the interface between the steel plate substrate and the bottom layer to expand, so that the magnesium silicate bottom layer is easy to peel off during the subsequent pickling process, and after complete peeling, the bottom-free oriented silicon steel is formed; and by non-uniformly coating the additive on the strip, the coating amount at the edge is greater than that in the middle, and differentiated adjustments are achieved in different regions, so that the quality of the edge and the middle reaches the best state, thereby reducing the bottom layer residue, reducing the trimming amount, and improving the yield rate.

[0042] It should be noted that if Figure 1 As shown, the coating of the additive of the present application can be before the drying furnace, after the drying furnace, or before and after the drying furnace. The method for manufacturing oriented electrical steel of the present application also includes steelmaking, hot rolling, normalizing annealing, cold rolling, decarburization and nitriding annealing, high temperature annealing, stretching and leveling annealing, and coating of insulating coating. The above processes all adopt the existing technology and will not be described in detail in this application.

[0043] As an implementation manner of an embodiment of the present invention, the coating area is divided into a first coating area, a second coating area and a third coating area, the third coating area is farther from the edge of the steel strip than the second spraying area, the second coating area is farther from the edge of the steel strip than the first coating area, the additive is uniformly coated on the surface of the steel strip in the first coating area, the additive is coated on the surface of the steel strip in the second coating area and the coating amount of the additive decreases from the outside to the inside along the width direction of the steel strip, and the additive is uniformly coated on the surface of the steel strip in the third coating area.

[0044] In the present application, the bottom layer residue at the edge of the strip is the heaviest, and the bottom layer in the middle has the best quality. By gradually setting the coating amount in the second coating area, the quality of the edge and the middle can reach the best state, and the straight edge coating can be avoided to form a corresponding dividing line on the finished product, which affects the apparent quality of the product and is not easily accepted by users.

[0045] As an implementation manner of the embodiment of the present invention, the method of coating the additive on the surface of the steel strip in the second coating zone and the coating amount of the additive decreasing from the outside to the inside along the width direction of the steel strip includes:

[0046] According to Wp and W0, the surface of the strip in the second coating zone is coated with additives in a decreasing trend from outside to inside along the width direction of the strip,

[0047] Wherein, Wp represents the distance between the coating site and the edge of the strip, and W0 represents the actual edge residual width of the bottom-free oriented electrical steel.

[0048] As an implementation manner of the embodiment of the present invention, the method of coating the additive on the surface of the steel strip in the second coating zone and the coating amount of the additive decreasing from the outside to the inside along the width direction of the steel strip includes:

[0049] The additive is applied to the surface of the strip in the second coating area starting from the critical line with the first coating area and in a coating amount shown in Expression 1. The second coating area satisfies W0≤W p Area ≤W0+200;

[0050] Expression 1:

[0051]

[0052] Wherein, m represents the coating amount, Wp represents the distance between the coating site and the edge of the strip, in mm, W0 represents the actual edge residual width of the bottom-free oriented electrical steel, in mm, and m represents the coating amount, in mm. a The coating amount of the first coating area is set to 15-50g / m 2 , the m b The coating amount of the third coating area is set to 11-27 g / m 2 .

[0053] In this application, if the coating amount is too small, the characteristic element content is low, and the effect of loosening the bottom layer and improving the residual defects of the bottom layer cannot be achieved; if the coating amount is too large, the special elements will have too severe a destructive effect on the bottom layer, which will reduce the protective effect of the bottom layer on the precipitates in the steel plate, causing the precipitates to mature quickly in advance and the magnetic properties to deteriorate. Therefore, the coating amount must be controlled within a certain reasonable range.

[0054] The amount of the second coating area is to ensure that the secondary edge of the plate width meets the quality requirements and there is no obvious visible boundary mark with the edges of the first and third spraying areas. Selecting an area 200mm away from the residual area of ​​the edge for gradual coating can effectively prevent the appearance of a boundary line and ensure that the middle area reaches the best state.

[0055] As an implementation manner of the embodiment of the present invention, the step of uniformly coating the surface of the steel strip in the first coating area with the additive comprises:

[0056] The uniform coating mass of the strip surface in the first coating area is m a The additive, the m a Set to 15~50g / m 2 ;

[0057] Wherein, the first coating area is an area satisfying Wp<W0, the W p represents the distance between the coating position and the edge of the strip, W represents the strip width, W0 represents the actual edge residual width of the oriented electrical steel without the bottom layer, and

[0058] In the present application, the amount of the first spraying zone is to ensure that the wide edge of the plate meets the quality requirements.

[0059] As an implementation manner of the embodiment of the present invention, the step of uniformly coating the surface of the strip steel in the third coating zone with the additive comprises:

[0060] The uniform coating mass of the strip surface in the third coating zone is m b The additive, the m b Set to 11~27g / m 2 ; and m a >m b ;

[0061] Wherein, the third coating area satisfies The area of ​​W p represents the distance between the coating position and the edge of the strip, W represents the width of the strip, W0 represents the actual residual width of the edge of the bottom-free oriented electrical steel, and

[0062] In this application, the amount of the third spraying zone is to ensure that the middle of the plate width meets the quality requirements.

[0063] As an implementation manner of the embodiment of the present invention, the isolation agent component is a mixture of silicon steel grade MgO and Al2O3, and the mass fraction of MgO in the mixture is 20%-100%.

[0064] As an implementation method of an embodiment of the present invention, the additive is formed by mixing component A with water, and component A is at least one of NaCl, KCl, MgCl2, ZnCl2, BaCl2, SrCl2, NH4Cl, MnCl2, CaCl2, BiOCl, SbOCl, Bi(NO3)2, Cu(NO3)2, NaNO3, and NH4NO3; the concentration of the additive is 5% to 10%.

[0065] In this application, the additive is Cl - or NO3 - compounds, or compounds that can react with H + The ions form acidic compounds, which corrode the bottom layer through the acidic atmosphere such as HCl or HNO3 formed during high-temperature annealing, making the bottom layer loose. The acid liquid easily invades the bottom layer during subsequent pickling, making it easier for the bottom layer to peel off the steel plate matrix. If the additive concentration is too low, the required spray volume is too large, the strip is not easy to dry, and too much water is introduced into the strip, which is prone to water vapor print defects; if the additive concentration is too high, the carrier solution is too little, and uneven spraying is prone to occur, which is reflected as point defects on the finished product. Therefore, the additive concentration value should be within an appropriate range.

[0066] As an implementation of the embodiment of the present invention, the droplet diameter of the additive coated is 10 to 300 μm.

[0067] In this application, if the droplet size of the additive coating is too small, the droplets are easily suspended in the environment under the high-speed operation of the strip steel, and cannot reach the surface of the strip steel; if the droplet size is too large, uneven coating is likely to occur, and point defects are likely to form on the surface of the strip steel. By controlling the droplet size of the additive, the coating effect is optimized.

[0068] As an implementation manner of an embodiment of the present invention, the step of applying the additive to the coating area includes:

[0069] The additive is applied to the coating area on one side and / or both sides of the surface of the steel strip.

[0070] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then proceed according to general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0071] Example 1

[0072] This embodiment provides a method for manufacturing oriented electrical steel with excellent surface quality, specifically: after the ingot is heated at 1150°C in a high-temperature annealing furnace, it is hot rolled to 2.5mm, annealed in two stages in a normalizing annealing furnace, and then cold rolled to 0.23mm. Next, the strip is sequentially subjected to decarburization and nitriding annealing, the entire plate surface is uniformly roll-coated with an isolation agent (MgO slurry), sprayed with additives, and coiled. Then, the steel coil is changed from horizontal to vertical, and enters a high-temperature annealing furnace for annealing at a maximum of 1200°C. After leaving the furnace, it is subjected to stress relief annealing and insulation coating in a hot stretching and leveling unit.

[0073] The additive is sprayed on one side of the strip along the width direction, with a spraying amount of m (g / m 2 ) is calculated as

[0074]

[0075] Wherein, Wp represents the distance between the spraying site and the edge of the strip, in mm;

[0076] The isolation agent is prepared by mixing NaCl2 and BiOCl in a mass ratio of 7:3 and then dissolving in water to a concentration of 8%.

[0077] The chemical composition of the low-temperature and high magnetic induction oriented silicon steel used in this embodiment is calculated by mass fraction as follows: C: 0.052%, Si: 3.0%, Mn: 0.08%, S: 0.010%, Als: 0.0245%, N: 0.0099%, Bi: 0.0045%, Sn: 0.20%, Cr: 0.05%, Cu: 0.25%, and the rest are Fe and unavoidable impurity elements.

[0078] Example 2

[0079] This embodiment provides a method for manufacturing oriented electrical steel with excellent surface quality, specifically: after the ingot is heated at 1150°C in a high-temperature annealing furnace, it is hot rolled to 2.5mm, annealed in two stages in a normalizing annealing furnace, and then cold rolled to 0.23mm. Next, the strip is sequentially subjected to decarburization and nitriding annealing, the entire plate surface is uniformly roll-coated with an isolation agent (MgO slurry), sprayed with additives, and coiled. Then, the steel coil is changed from horizontal to vertical, and enters a high-temperature annealing furnace for annealing at a maximum of 1200°C. After leaving the furnace, it is subjected to stress relief annealing and insulation coating in a hot stretching and leveling unit.

[0080] The additive is sprayed on both the upper and lower surfaces of the strip along the width direction, with a spraying amount of m (g / m 2 ) is calculated as

[0081]

[0082] Wherein, Wp represents the distance between the spraying site and the edge of the strip, in mm;

[0083] The isolation agent is prepared by mixing MgCl2, SbOCl and NH4NO3 in a mass ratio of 1:2:7 and then dissolving in water, with a concentration of 7%.

[0084] The chemical composition of the low-temperature and high magnetic induction oriented silicon steel used in this embodiment is calculated by mass fraction as follows: C: 0.052%, Si: 3.0%, Mn: 0.08%, S: 0.010%, Als: 0.0245%, N: 0.0099%, Bi: 0.0005%, Sn: 0.20%, Cr: 0.05%, Cu: 0.25%, and the rest are Fe and unavoidable impurity elements.

[0085] Example 3

[0086] This embodiment provides a method for manufacturing oriented electrical steel with excellent surface quality, specifically: after the ingot is heated at 1150°C in a high-temperature annealing furnace, it is hot rolled to 2.5mm, annealed in two stages in a normalizing annealing furnace, and then cold rolled to 0.23mm. Next, the strip is sequentially subjected to decarburization and nitriding annealing, the entire plate surface is uniformly roll-coated with an isolation agent (MgO slurry), sprayed with additives, and coiled. Then, the steel coil is changed from horizontal to vertical, and enters a high-temperature annealing furnace for annealing at a maximum of 1200°C. After leaving the furnace, it is subjected to stress relief annealing and insulation coating in a hot stretching and leveling unit.

[0087] The additive is sprayed on one side of the lower surface of the strip along the width direction, and the spraying amount is m (g / m 2 ) is calculated as

[0088]

[0089] Wherein, Wp represents the distance between the spraying site and the edge of the strip, in mm;

[0090] The isolation agent is made by mixing ZnCl2, SrCl2 and Cu(NO3)2 in a mass ratio of 3:2:5 and then dissolving in water, and its concentration is 8%.

[0091] The chemical composition of the low-temperature and high magnetic induction oriented silicon steel used in this embodiment is calculated by mass fraction as follows: C: 0.052%, Si: 3.0%, Mn: 0.08%, S: 0.010%, Als: 0.0245%, N: 0.0099%, Bi: 0.05%, Sn: 0.20%, Cr: 0.05%, Cu: 0.25%, and the rest are Fe and unavoidable impurity elements.

[0092] Comparative Example 1

[0093] The spraying additive in Example 1 is eliminated, and the rest is the same as Example 1.

[0094] Comparative Example 2

[0095] The spraying amount of the additive in Example 1 is m (g / m 2 ) is changed to:

[0096] The rest is the same as Example 1.

[0097] Comparative Example 3

[0098] The concentration of the additive in Example 2 was changed to 20%, and the rest was the same as Example 2.

[0099] Table 1 Implementation effects of embodiments and comparative examples

[0100]

[0101] In summary, the method for manufacturing oriented electrical steel with excellent surface quality provided by the present invention adopts a segmented and gradual control mode based on the bottom layer generation characteristics of the bottom-free oriented steel, which can effectively realize the differentiated adjustment of defective areas and normal areas, so that the quality of the edges and the middle can reach the best bottom-free state, ensuring the uniformity of the plate surface quality.

[0102] It should be noted that, in this article, relational terms such as "first" and "second" are only used 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. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0103] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be 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 the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for producing oriented electrical steel with excellent surface quality, characterized in that: The method comprises applying a release agent to the oriented electrical steel and then applying an additive; The chemical composition of the oriented electrical steel strip includes: 0.0005% (weight) to 0.05% (weight) of Bi; The method of applying the additive after applying the release agent comprises: firstly uniformly applying the release agent on the surface of the steel strip, then dividing the surface of the steel strip from the edge to the middle along the width direction into a plurality of coating areas according to the distance from the edge of the steel strip, and applying the additive to the coating areas, wherein the coating area closer to the edge of the steel strip has a larger coating amount of the additive; The additive is formed by mixing component A with water, wherein component A is at least one of NaCl, KCl, MgCl2, ZnCl2, BaCl2, SrCl2, NH4Cl, MnCl2, CaCl2, BiOCl, SbOCl, Bi(NO3)2, Cu(NO3)2, NaNO3, and NH4NO3; and the concentration of the additive is 5% to 10%.

2. The method for producing surface-quality oriented electrical steel according to claim 1, characterized in that: The coating area is divided into a first coating area, a second coating area and a third coating area. The third coating area is farther from the edge of the steel strip than the second coating area, and the second coating area is farther from the edge of the steel strip than the first coating area. The additive is uniformly coated on the surface of the steel strip in the first coating area, the additive is coated on the surface of the steel strip in the second coating area and the coating amount of the additive decreases from the outside to the inside along the width direction of the steel strip, and the additive is uniformly coated on the surface of the steel strip in the third coating area.

3. The method for producing surface-quality oriented electrical steel according to claim 2, characterized in that: The step of coating the additive on the surface of the steel strip in the second coating zone and wherein the coating amount of the additive decreases from the outside to the inside along the width direction of the steel strip, comprises: According to Wp and W0, the surface of the strip in the second coating zone is coated with additives in a decreasing trend from outside to inside along the width direction of the strip, Wherein, Wp represents the distance between the coating site and the edge of the strip, and W0 represents the actual edge residual width of the oriented electrical steel.

4. The method for producing surface-quality oriented electrical steel according to claim 2 or 3, characterized in that: The step of coating the additive on the surface of the steel strip in the second coating zone and wherein the coating amount of the additive decreases from the outside to the inside along the width direction of the steel strip, comprises: The additive is applied to the surface of the strip steel in the second coating area starting from the critical line with the first coating area and in a coating amount shown in Expression 1. The second coating area satisfies area; Expression 1: ； Wherein, m represents the coating amount, Wp represents the distance between the coating site and the edge of the strip, in mm, W0 represents the actual residual width of the edge of the oriented electrical steel, in mm, and , the m a The coating amount of the first coating area is set to 15~50g / m 2 , the m b The coating amount of the third coating area is set to 11~27g / m 2 , W represents the strip width.

5. The method for producing surface-quality oriented electrical steel according to claim 2, characterized in that: The step of uniformly coating the surface of the steel strip in the first coating zone with the additive comprises: The uniform coating mass of the strip surface in the first coating area is m a The additive, the m a Set to 15~50g / m 2 ; Wherein, the first coating area satisfies The area of ​​W p represents the distance between the coating position and the edge of the strip, W represents the strip width, W0 represents the actual residual width of the edge of the oriented electrical steel, and .

6. The method for producing surface-quality oriented electrical steel according to claim 2, characterized in that: The step of uniformly coating the surface of the steel strip in the third coating zone with the additive comprises: The uniform coating mass of the strip surface in the third coating zone is m b The additive, the m b Set to 11~27g / m 2 ; and m a >m b ; Wherein, the third coating area satisfies The area of ​​W p represents the distance between the coating position and the edge of the strip, W represents the width of the strip, W0 represents the actual residual width of the edge of the oriented electrical steel, and .

7. The method for producing surface-quality oriented electrical steel according to claim 1, characterized in that: The isolation agent component is a mixture of silicon steel grade MgO and Al2O3, and the mass fraction of MgO in the mixture is 20%-100%.

8. The method for producing surface-quality grain-oriented electrical steel according to claim 1, characterized in that: The droplet particle size of the additive coated is 10-300 μm.

9. The method for producing surface-quality oriented electrical steel according to claim 1, characterized in that: The step of applying the additive to the coating area comprises: The additive is applied to the coating area on one side and / or both sides of the surface of the steel strip.

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