阅读说明：本技术 一种无底层取向硅钢的制备方法及其产品 (Preparation method of non-bottom-layer oriented silicon steel and product thereof ) 是由 王现辉 孙茂林 龚坚 肖辉明 高倩 刘兆月 滕仁昊 赵松山 胡志远 齐杰斌 游学 于 2020-12-17 设计创作，主要内容包括：本发明属于硅钢制备技术领域,具体涉及一种无底层取向硅钢的制备方法。其中,所述脱碳退火的过程中,带钢表层的氧化膜厚度为1.5～2.5μm；所述氧化膜中Si元素和Fe元素的原子重量比满足：Si/(Si+Fe)≥0.76；所述高温退火的过程中,冷却段依次包括：在温度为1200～500℃时,罩内冷却；其中,保护气体为包括有氮气和氢气的混合气体,所述混合气体中氢气的体积百分比＞3％；在温度为500～200℃时,罩内冷却；其中,保护气体为氮气；在温度＜200℃时,揭开内罩进行空气冷却。本发明提供的无底层取向硅钢的制备方法中,通过控制带钢在脱碳退火阶段的氧化膜厚度以及高温退火的冷却段等一些工艺,从而得到了表面光洁化好、表面均质化好、成材率高、磁性能优良的无底层取向硅钢。(The invention belongs to the technical field of silicon steel preparation, and particularly relates to a preparation method of non-bottom-layer oriented silicon steel. Wherein in the decarburization annealing process, the thickness of an oxide film on the surface layer of the strip steel is 1.5-2.5 μm; the atomic weight ratio of the Si element to the Fe element in the oxide film satisfies the following conditions: Si/(Si + Fe) is not less than 0.76; in the high-temperature annealing process, the cooling section sequentially comprises: cooling in a cover when the temperature is 1200-500 ℃; wherein the protective gas is a mixed gas comprising nitrogen and hydrogen, and the volume percentage of the hydrogen in the mixed gas is more than 3 percent; cooling in a cover at the temperature of 500-200 ℃; wherein the protective gas is nitrogen; at a temperature of less than 200 ℃, the inner cover is uncovered for air cooling. According to the preparation method of the non-underlayer oriented silicon steel, the non-underlayer oriented silicon steel with good surface smoothness, good surface homogenization, high yield and excellent magnetic performance is obtained by controlling the thickness of the oxide film of the strip steel in the decarburization annealing stage, the cooling section of high-temperature annealing and other processes.)

1. A preparation method of the non-bottom oriented silicon steel comprises the following steps: smelting, continuous casting, heating of a casting blank, hot rolling, normalizing, cold rolling, decarburization annealing, nitriding, coating of a separant, high-temperature annealing, hot stretching flattening and coating; the method is characterized in that:

in the decarburization annealing process, the thickness of an oxide film on the surface layer of the strip steel is 1.5-2.5 mu m; the atomic weight ratio of the Si element to the Fe element in the oxide film satisfies the following conditions: Si/(Si + Fe) is not less than 0.76;

in the high-temperature annealing process, the cooling section sequentially comprises:

cooling in a cover when the temperature is 1200-500 ℃; wherein the protective gas is a mixed gas comprising nitrogen and hydrogen, and the volume percentage of the hydrogen in the mixed gas is more than 3 percent;

cooling in a cover at the temperature of 500-200 ℃; wherein the protective gas is nitrogen;

at a temperature of less than 200 ℃, the inner cover is uncovered for air cooling.

2. The method of manufacturing non-primer oriented silicon steel as set forth in claim 1, wherein the release agent comprises, during the step of coating the release agent: component A, component B, component C and component D;

wherein the component A is MgO, or the component A comprises MgO and Al₂O₃A mixture of (a);

the component B is selected from NaCl, KCl and MgCl₂、ZnCl₂、BaCl₂、SrCl₂、MnCl₂、CaCl₂、BiOCl、SbOCl、Bi(NO₃)₂、Cu(NO₃)₂、NaNO₃、NO₃NH₄One or more than two of the above;

the component C is a low-melting-point compound with a melting point less than or equal to 820 ℃;

the component D is CaO or Ca (OH)₂。

3. The method of claim 2, wherein the grain-oriented silicon steel comprises MgO and Al₂O₃In the mixture of (a): the Al is₂O₃The mass fraction is less than or equal to 60 percent, and the granularity is more than or equal toThe volume percentage of the 10 mu m particles is 30-60%.

4. The method for preparing the bottom-layer-free oriented silicon steel according to claim 2 or 3, wherein the citric acid activity of MgO is 200-2000S;

the Al is₂O₃The specific surface area of (A) is 15 to 50m²/g。

5. The method for preparing the non-bottom oriented silicon steel according to claim 1 or 2, wherein the low-melting-point compound with the melting point less than or equal to 820 ℃ is one or more than two of boron oxide, sodium carbonate, borax and antimony oxide.

6. The method for preparing the bottom-layer-free oriented silicon steel as claimed in claim 1 or 2, wherein the weight ratio of the component A, the component B, the component C and the component D in the separant is 100 (0.5-6): 0.6-3): 0.6-5.3.

7. The method of manufacturing non-primer oriented silicon steel of claim 5, wherein the release agent further comprises NH in mass fraction₄Cl；

In the release agent, the component A and the NH₄The mass ratio of Cl is 100 (1-2.1).

8. The method for preparing the bottom-layer-free oriented silicon steel as claimed in claim 1 or 2, wherein a four-stage cleaning process is adopted in the hot-drawing leveling process, and the four-stage cleaning process sequentially comprises the following steps:

cleaning with water;

acid washing is carried out by adopting a mixed solution containing 1-10% of sulfuric acid and 1-5% of nitric acid; wherein the pickling temperature is 50-80 ℃;

cleaning with a mixture comprising water and a Fe ion complexing agent; wherein in the mixture, the mass concentration of the Fe ion complexing agent is 0.5-5%;

and washing with water.

9. The method for preparing the bottom-layer-free oriented silicon steel according to claim 1 or 2, wherein the dew point in the decarburization annealing process is 38-58 ℃; the heating temperature is 800-850 ℃.

10. The bottom-free oriented silicon steel obtained by the method for preparing the bottom-free oriented silicon steel according to any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of silicon steel preparation, and particularly relates to a preparation method of non-bottom-layer oriented silicon steel and a product thereof.

Background

In the conventional process for manufacturing oriented silicon steel, the strip steel needs to be decarburized and annealed after being cold-rolled, and an oxide film (made of SiO) is formed on the surface of the strip steel₂And Fe₂SiO₄Composition) and then nitrided. In the nitriding process, N element permeates into the surface layer of the strip steel through an oxide film. Then coating a layer of MgO isolating agent on the surface of the strip steel. When the strip steel enters a high-temperature annealing stage, an oxide film formed on the surface of the strip steel reacts with MgO to generate a magnesium silicate bottom layer. The magnesium silicate underlayer can increase the interlayer resistance of the surface of the strip steel and provide surface tension to improve the magnetic performance of the strip steel. However, such a bottom layer may cause poor punching performance of the conventional oriented silicon steel. In addition, the oxide generated on the surface of the strip steel of the bottom layer can hinder the magnetic domain movement and prevent the ironThe impairment has a certain worsening effect.

At present, the oriented silicon steel without the bottom layer is an important direction for the development of the oriented silicon steel, has excellent magnetic conductivity and non-oriented excellent processability of the oriented silicon steel, and has wide application prospect in the field of manufacturing of high-energy-efficiency motors and generators. In addition, the surface of the silicon steel without the bottom layer can be polished to further improve the magnetic performance level of the oriented silicon steel.

However, the main problems of current non-bottom oriented silicon steels are: (1) the surface of the non-bottom oriented silicon steel is difficult to be polished; (2) the non-bottom oriented silicon steel is easy to generate the defect of unstable magnetic performance; (3) in the production process of the non-bottom oriented silicon steel, the homogenization of the surface and the magnetic property of the strip steel is difficult to control due to the difference of the production temperature and the atmosphere of a large steel coil; (4) the yield of the oriented silicon steel without the bottom layer is low.

Therefore, it is necessary to develop a method for preparing a non-bottom oriented silicon steel to solve the problems of surface smoothness and homogenization of the non-bottom oriented silicon steel.

Disclosure of Invention

In view of the above problems, the present invention provides a method for preparing non-underlayer oriented silicon steel and a product thereof. According to the preparation method of the non-underlayer oriented silicon steel, the non-underlayer oriented silicon steel with good surface smoothness, good surface homogenization, high yield and excellent magnetic performance is obtained by controlling the thickness of the oxide film of the strip steel in the decarburization annealing stage, the cooling section of high-temperature annealing and other processes.

The technical scheme of the invention for realizing the purpose is as follows:

in one aspect of the present invention, there is provided a method of preparing a primer-free oriented silicon steel, comprising: smelting, continuous casting, heating of a casting blank, hot rolling, normalizing, cold rolling, decarburization annealing, nitriding, coating of a separant, high-temperature annealing, hot stretching flattening and coating; wherein:

in the decarburization annealing process, the thickness of an oxide film on the surface layer of the strip steel is 1.5-2.5 mu m; the atomic weight ratio of the Si element to the Fe element in the oxide film satisfies the following conditions: Si/(Si + Fe) is not less than 0.76;

in the high-temperature annealing process, the cooling section sequentially comprises:

cooling in a cover when the temperature is 1200-500 ℃; wherein the protective gas is a mixed gas comprising nitrogen and hydrogen, and the volume percentage of the hydrogen in the mixed gas is more than 3 percent;

cooling in a cover at the temperature of 500-200 ℃; wherein the protective gas is nitrogen;

at a temperature of less than 200 ℃, the inner cover is uncovered for air cooling.

In some embodiments of the present invention, in the method for preparing the non-bottom oriented silicon steel, the heating temperature is 1150 ℃ during the billet heating process.

In some embodiments of the present invention, in the method for preparing a non-underlayer oriented silicon steel, the thickness of the oxide film on the surface layer of the strip steel is 1.5 to 2.5 μm, and the method includes:

the thickness of the oxide film on the surface layer of the strip steel is 1.9-2.3 mu m.

In some embodiments of the present invention, in the method for preparing a non-underlayer oriented silicon steel, the release agent comprises: component A, component B, component C and component D;

wherein the component A is MgO, or the component A comprises MgO and Al₂O₃A mixture of (a);

the component B is selected from NaCl, KCl and MgCl₂、ZnCl₂、BaCl₂、SrCl₂、MnCl₂、CaCl₂、BiOCl、SbOCl、Bi(NO₃)₂、Cu(NO₃)₂、NaNO₃、NO₃NH₄One or more than two of the above;

the component C is a low-melting-point compound with a melting point less than or equal to 820 ℃;

the component D is CaO or Ca (OH)₂。

In some embodiments of the invention, the method for preparing the non-underlayer oriented silicon steel comprises the following steps₂O₃In the mixture of (a): the Al is₂O₃Quality of (1)The mass fraction is less than or equal to 60 percent, and the volume percentage of the particles with the particle size of more than or equal to 10 mu m is 30-60 percent.

In some embodiments of the invention, the method for preparing the non-underlayer oriented silicon steel comprises the following steps₂O₃In the mixture of (1), the MgO and the Al₂O₃In a mass ratio of 90: 5.

In some embodiments of the present invention, in the method for preparing the bottom-layer-free oriented silicon steel, the citric acid activity of the MgO is 200 to 2000S;

the Al is₂O₃The specific surface area of (A) is 15 to 50m²/g。

In some embodiments of the present invention, in the method for preparing the non-bottom oriented silicon steel, the low melting point compound with a melting point of 820 ℃ or less is selected from one or more of boron oxide, sodium carbonate, borax and antimony oxide.

In some embodiments of the present invention, in the method for preparing the non-underlayer oriented silicon steel, the low melting point compound with the melting point of less than or equal to 820 ℃ is boron oxide or antimony oxide.

In some embodiments of the invention, in the preparation method of the bottom-layer-free oriented silicon steel, the mass ratio of the component A, the component B, the component C and the component D in the separant is 100 (0.5-6): 0.6-3): 0.6-5.3.

In some embodiments of the invention, in the method for preparing the bottom-layer-free oriented silicon steel, the separant further comprises NH in mass fraction₄Cl；

In the release agent, the component A and the NH₄The mass ratio of Cl is 100 (1-2.1).

In some embodiments of the present invention, in the method of making a non-underlayer oriented silicon steel of the present invention, the release agent comprises: component A, component B, component C, component D and NH₄Cl；

In the release agent, the component A, the component B, the component C, the component D and NH₄ClThe mass ratio of (1) to (2) to (5) to (1.9).

In some embodiments of the present invention, in the method for preparing the non-underlayer oriented silicon steel, the component A is a composition containing MgO and Al₂O₃A mixture of (a);

the component B is MgCl₂；

The component C is antimony oxide;

the component D is Ca (OH)₂。

In some embodiments of the present invention, in the method for preparing a non-bottom oriented silicon steel, a four-stage cleaning process is adopted in the hot-drawing leveling process, and the four-stage cleaning process sequentially includes:

cleaning with water;

acid washing is carried out by adopting a mixed solution containing 1-10% of sulfuric acid and 1-5% of nitric acid; wherein the pickling temperature is 50-80 ℃;

cleaning with a mixture comprising water and a Fe ion complexing agent; wherein in the mixture, the mass concentration of the Fe ion complexing agent is 0.5-5%;

and washing with water.

In some embodiments of the invention, in the preparation method of the bottom-layer-free oriented silicon steel, the dew point during the decarburization annealing is 38-58 ℃; the heating temperature is 800-850 ℃.

In some embodiments of the present invention, in the method for preparing a non-underlayer oriented silicon steel, the Fe ion complexing agent may be ammonium citrate. In the technical scheme, the ammonium citrate can further prevent the residual Fe ions on the surface of the strip steel from being oxidized, so that a good surface is obtained.

In some embodiments of the present invention, in the method for preparing a non-underlayer oriented silicon steel, the cast slab comprises, by mass: 0.05-0.09% of C, 2.9-4.6% of Si, 0.05-0.20% of Mn, 0.005-0.020% of S, 0.0225-0.0325% of Als, 0.0045-0.0145% of N, 0.01-0.30% of Sn, 0.002-0.15% of Sb, 0.01-0.5% of Cr, 0.01-0.8% of Cu, and the balance of Fe and inevitable impurity elements.

In some embodiments of the present invention, in the method for preparing a non-underlayer oriented silicon steel, the cast slab comprises, by mass: 0.06 to 0.07% of C, 3.2 to 3.5% of Si, 0.16 to 0.17% of Mn, 0.015 to 0.019% of S, 0.028 to 0.030% of Als, 0.012 to 0.013% of N, 0.10 to 0.20% of Sn, 0.09 to 0.11% of Sb, 0.3 to 0.4% of Cr, 0.1 to 0.3% of Cu, and the balance of Fe and inevitable impurity elements.

In another aspect of the invention, the invention also provides the non-bottom-layer oriented silicon steel obtained by the preparation method of the non-bottom-layer oriented silicon steel.

In some embodiments of the present invention, the thickness of the non-bottom oriented silicon steel obtained by the method for preparing the non-bottom oriented silicon steel of the present invention may be 0.18mm, 0.20mm, 0.23mm, 0.27mm, 0.30mm, or 0.35 mm.

One or more technical embodiments of the present invention have at least the following technical effects or advantages:

(1) according to the preparation method of the non-bottom oriented silicon steel, the non-bottom oriented silicon steel with good surface smoothness, good surface homogenization, high yield and excellent magnetic performance can be obtained by controlling the thickness of the oxide film of the strip steel in the decarburization annealing stage and the high-temperature annealing cooling section process.

(2) In the preparation method of the non-bottom oriented silicon steel, aiming at the invention, through a large number of optimization balance tests, specific components and content of the separant are selected and matched with a series of specific process parameters, and the obtained non-bottom oriented silicon steel has the advantages of uniform and bright surface formation state, small oxide residual degree, no obvious steam mark and small friction coefficient.

(3) According to the preparation method of the non-bottom oriented silicon steel, the thickness of the oxide film of the strip steel in the decarburization annealing stage and the high-temperature annealing cooling section process are controlled, the hot stretching flattening process is optimized, the four-section cleaning process is selected, the defects of poor surface uniformity, poor finish degree, low yield, poor magnetic performance and the like of the non-bottom oriented silicon steel can be better solved, the non-bottom oriented silicon steel with uniform surface, excellent finish degree and good magnetic performance is obtained, and the qualified rate is more than 90%.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.

Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

In order to solve the technical problems, the embodiments of the present invention provide the following general ideas:

in one aspect of the present invention, there is provided a method of preparing a primer-free oriented silicon steel, comprising: smelting, continuous casting, heating of a casting blank, hot rolling, normalizing, cold rolling, decarburization annealing, nitriding, coating of a separant, high-temperature annealing, hot stretching flattening and coating; wherein:

in the decarburization annealing process, the thickness of an oxide film on the surface layer of the strip steel is 1.5-2.5 mu m; the atomic weight ratio of the Si element to the Fe element in the oxide film satisfies the following conditions: Si/(Si + Fe) is not less than 0.76;

in the high-temperature annealing process, the cooling section sequentially comprises:

cooling in a cover when the temperature is 1200-500 ℃; wherein the protective gas is a mixed gas comprising nitrogen and hydrogen, and the volume percentage of the hydrogen in the mixed gas is more than 3 percent;

cooling in a cover at the temperature of 500-200 ℃; wherein the protective gas is nitrogen;

at a temperature of less than 200 ℃, the inner cover is uncovered for air cooling.

In the preparation method of the non-bottom oriented silicon steel, the low-activity compact oxide film is obtained by controlling the thickness of the oxide film of the strip steel in the decarburization annealing stage to prevent the generation of magnesium aluminate spinel, and the rough surface of the final product caused by the attachment of a large amount of iron elements reduced by iron oxides in the oxide film on the surface of the strip steel is prevented. In addition, the process parameters of the strip steel in the high-temperature annealing cooling section are controlled, so that the non-underlayer oriented silicon steel with good surface finish, good surface homogenization, high yield and excellent magnetic performance is obtained.

In some embodiments of the present invention, in the method for preparing non-bottom oriented silicon steel, the heating temperature is 1150 ℃ during the heating of the casting blank.

In the preparation method of the non-bottom oriented silicon steel provided by the invention, the inventor conducts a great deal of research on the heating temperature of the casting blank, and finally selects the most suitable heating temperature to be 1150 ℃, so that the yield of the prepared non-bottom oriented silicon steel is higher.

In some embodiments of the present invention, in the method for preparing a non-underlayer oriented silicon steel, the thickness of the oxide film on the surface layer of the strip steel is 1.5 to 2.5 μm, and the method includes:

the thickness of the oxide film on the surface layer of the strip steel is 1.9-2.3 mu m.

In the preparation method of the non-bottom oriented silicon steel provided by the invention, the inventor also conducts a great deal of research on the preferable scheme of the thickness of the oxide film on the surface layer of the strip steel (the thickness of the oxide film is 1.9-2.3 mu m), thereby greatly promoting the surface quality of the final product.

In some embodiments of the present invention, in the method for preparing a non-underlayer oriented silicon steel, the release agent comprises: component A, component B, component C and component D;

wherein the component A is MgO, or the component A comprises MgO and Al₂O₃Mixture of；

The component B is selected from NaCl, KCl and MgCl₂、ZnCl₂、BaCl₂、SrCl₂、MnCl₂、CaCl₂、BiOCl、SbOCl、Bi(NO₃)₂、Cu(NO₃)₂、NaNO₃、NO₃NH₄One or more than two of the above;

the component C is a low-melting-point compound with a melting point less than or equal to 820 ℃;

the component D is CaO or Ca (OH)₂。

In the preparation method of the non-bottom oriented silicon steel provided by the invention, through a large number of optimization balance tests, the specific components and the content of the separant are selected and matched with a series of process parameters, and the obtained non-bottom oriented silicon steel has the advantages of uniform and bright surface formation state, small oxide residue, no obvious steam mark and small friction coefficient.

In some embodiments of the present invention, in the method for preparing the non-underlayer oriented silicon steel, the silicon steel contains MgO and Al₂O₃In the mixture of (1), the MgO and the Al₂O₃In a mass ratio of 90: 5.

In the preparation method of the non-bottom oriented silicon steel provided by the invention, the inventor selects the silicon steel containing MgO and Al through a large number of optimization balance tests₂O₃In the mixture of (1), the MgO and the Al₂O₃The mass ratio of the components is 90:5, and the smoothness and uniformity of the surface of the strip steel are further improved.

In some embodiments of the invention, in the method for preparing the bottom-layer-free oriented silicon steel, the citric acid activity of the MgO is 200-2000S;

in the separant, the volume percentage of particles with the granularity of more than or equal to 10 mu m is 30-60%;

the Al is₂O₃The specific surface area of (A) is 15 to 50m²/g。

As a result of extensive studies, the inventors of the present invention have found that MgO can be controlled more effectively while achieving the object of the present inventionThe reactivity is avoided, and the phenomenon that the uniformity of the surface of the strip steel is not good due to the too fast reaction between the oxide film and the oxide film is avoided. In addition, by adding CaO or Ca (OH)₂The slurry adhesion of the release agent is improved to more effectively avoid the defect of uneven surface quality caused by uneven coating. Furthermore, the invention also limits the particle size of the release agent to reduce the hydration rate, simultaneously improves the air permeability between high-temperature annealing layers, and better avoids the defect of water vapor mark on the surface of the strip steel caused by uneven water vapor release.

In some embodiments of the present invention, in the method for preparing non-bottom oriented silicon steel, the low melting point compound with a melting point less than or equal to 820 ℃ is selected from one or more of boron oxide, sodium carbonate, borax, and antimony oxide.

In some embodiments of the present invention, in the method for preparing the non-underlayer oriented silicon steel, the low melting point compound having a melting point of 820 ℃ or less is boron oxide or antimony oxide.

The inventors consider that MgO and oxide film SiO in high temperature annealing₂Reaction to form Mg₂SiO₄The bottom layer belongs to solid phase reaction, and the low melting point compound with the melting point less than or equal to 820 ℃ can generate liquid phase in high-temperature annealing, promote mass transfer process to accelerate the formation speed and porosity of the bottom layer, and is easier to remove in subsequent processes. Meanwhile, the low-melting-point compound with the melting point less than or equal to 820 ℃ can be beneficial to improving the uniformity of the surface of the steel, and has a certain control effect on the decomposition of an inhibitor on the surface layer of the steel, thereby being beneficial to stabilizing the magnetic performance of the steel.

In some embodiments of the invention, in the preparation method of the bottom-layer-free oriented silicon steel, the mass ratio of the component A, the component B, the component C and the component D in the separant is 100 (0.5-6): 0.6-3): 0.6-5.3.

In the preparation method of the bottomless oriented silicon steel, the specific components and the content of the separant are optimized aiming at the invention purpose, so that the surface finish and the homogenization of the magnetic property of the bottomless oriented silicon steel are greatly promoted, and the magnetic property of the bottomless oriented silicon steel is more stable.

In some embodiments of the invention, in the method for preparing the bottom-layer-free oriented silicon steel, the separant further comprises NH in percentage by mass₄Cl；

In the release agent, the component A and the NH₄The mass ratio of Cl is 100 (1-2.1).

The inventors considered NH through a great deal of research₄NH is released by Cl pyrolysis₃Gas, Si capable of nitriding surface layer of strip steel₃N₄The decomposition of the inhibitor plays a certain role in inhibiting, and further the effect of preventing the unstable magnetic property of the steel caused by the too fast decomposition of the inhibitor is enhanced.

In some embodiments of the present invention, in the method of preparing a non-underlayer oriented silicon steel of the present invention, the release agent comprises: component A, component B, component C, component D and NH₄Cl；

In the release agent, the component A, the component B, the component C, the component D and NH₄The mass ratio of Cl is 100:3:2:5: 1.9.

The content ratio of specific components of the separant is further optimized, and the surface smoothness, surface homogeneity and magnetic performance are greatly promoted on the basis of remarkably improving the yield of the non-bottom oriented silicon steel.

In some embodiments of the present invention, in the method for preparing the non-underlayer oriented silicon steel, the component A comprises MgO and Al₂O₃A mixture of (a);

the component B is MgCl₂；

The component C is antimony oxide;

the component D is Ca (OH)₂。

The invention is more beneficial to realizing the technical effect of the invention by selecting specific separant components, the final product is uniform and bright, and the oxide residue is less than or equal to 0.03g/m²No obvious steam mark and friction coefficient less than 0.25.

In some embodiments of the present invention, in the method for preparing a non-bottom oriented silicon steel, a four-stage cleaning process is adopted in the hot-drawing leveling process, and the four-stage cleaning process sequentially includes:

cleaning with water;

acid washing is carried out by adopting a mixed solution containing 1-10% of sulfuric acid and 1-5% of nitric acid; wherein the pickling temperature is 50-80 ℃;

cleaning with a mixture comprising water and a Fe ion complexing agent; wherein in the mixture, the mass concentration of the Fe ion complexing agent is 0.5-5%;

and washing with water.

In the preparation method of the non-bottom oriented silicon steel, a four-stage cleaning process is adopted in the hot stretching and flattening process, a certain amount of nitric acid is added to remove residual iron and iron oxide in the high-temperature annealing and cooling stage, and meanwhile, the roughness of the surface of the strip steel is further reduced, so that a smooth surface can be obtained. In addition, in the cleaning process, the mixture containing water and the Fe ion complexing agent is used for rinsing, so that the iron ions remained on the surface of the strip steel after the pickling process can be removed, and the defect that the surface of the strip steel is yellowed due to secondary oxidation caused by the iron ions remained on the surface of the strip steel after the cleaning section is finished is avoided.

In some embodiments of the invention, in the preparation method of the bottom-layer-free oriented silicon steel, the dew point is 38-58 ℃ in the decarburization annealing process; the heating temperature is 800-850 ℃.

In the present invention, in order to better achieve the object of the present invention, the dew point and heating temperature during decarburization annealing are controlled to ensure not only decarburization effect but also the target thickness of the oxide film of the present invention, and at the same time, SiO with a dense surface can be obtained₂And the layer can control the uniformity of the magnesium silicate generation reaction speed in the high-temperature annealing process.

In some embodiments of the present invention, in the method for preparing a non-underlayer oriented silicon steel, the cast slab includes, by mass: 0.05-0.09% of C, 2.9-4.6% of Si, 0.05-0.20% of Mn, 0.005-0.020% of S, 0.0225-0.0325% of Als, 0.0045-0.0145% of N, 0.01-0.30% of Sn, 0.002-0.15% of Sb, 0.01-0.5% of Cr, 0.01-0.8% of Cu, and the balance of Fe and inevitable impurity elements.

In some embodiments of the present invention, in the method for preparing a non-underlayer oriented silicon steel, the cast slab includes, by mass: 0.06 to 0.07% of C, 3.2 to 3.5% of Si, 0.16 to 0.17% of Mn, 0.015 to 0.019% of S, 0.028 to 0.030% of Als, 0.012 to 0.013% of N, 0.10 to 0.20% of Sn, 0.09 to 0.11% of Sb, 0.3 to 0.4% of Cr, 0.1 to 0.3% of Cu, and the balance of Fe and inevitable impurity elements.

In order to better realize the technical effect of the invention, the inventor selects and optimizes the chemical elements and the content of the chemical elements of the casting blank, thereby obtaining the non-bottom oriented silicon steel with more uniform surface, better brightness, lower friction coefficient, higher qualification rate and better magnetic property.

The method for preparing the non-primer oriented silicon steel according to the present invention will be described in detail with reference to examples, comparative examples and experimental data.

Example (b):

this example uses 8 test groups. In test groups 1 to 8, the method for preparing the non-bottom oriented silicon steel provided by some embodiments of the invention comprises the following steps: smelting, continuous casting, heating of a casting blank, hot rolling, normalizing, cold rolling, decarburization annealing, nitriding, coating of a separant, high-temperature annealing, hot stretching flattening and coating.

Specifically, a casting blank obtained by smelting and continuous casting is heated, heat-preserved, hot-rolled into a hot-rolled plate, and then normalized and cold-rolled into a cold-rolled plate by twenty rolls; and (3) carrying out decarburization annealing, nitriding, coating an isolating agent, drying, carrying out high-temperature annealing, carrying out hot stretching flattening and coating on the cold-rolled sheet to obtain a finished product. Wherein:

a casting blank heating stage: the heating temperature was 1150 ℃.

And (3) decarburization annealing stage: the thickness of the oxide film on the surface layer of the strip steel is 1.5-2.5 mu m; the atomic weight ratio of the Si element to the Fe element in the oxide film satisfies the following conditions: Si/(Si + Fe) is not less than 0.76; in the decarburization annealing process, the dew point is 38-58 ℃; the heating temperature is 800-850 ℃;

and (3) a release agent coating stage: the release agent comprises: component A, component B, component C, component D and NH₄Cl；

Wherein the component A is MgO, or the component A comprises MgO and Al₂O₃A mixture of (a); the composition contains MgO and Al₂O₃In the mixture of (1), the Al₂O₃The mass fraction is less than or equal to 60 percent, and the volume percentage of particles with the particle size of more than or equal to 10 mu m is 30-60 percent; the citric acid activity of the MgO is 200-2000S; the Al is₂O₃The specific surface area of (A) is 15 to 50m²/g。

The component B is selected from NaCl, KCl and MgCl₂、ZnCl₂、BaCl₂、SrCl₂、MnCl₂、CaCl₂、BiOCl、SbOCl、Bi(NO₃)₂、Cu(NO₃)₂、NaNO₃、NO₃NH₄One or more than two of the above;

the component C is a low-melting-point compound with a melting point of less than or equal to 820 ℃, and the low-melting-point compound with the melting point of less than or equal to 820 ℃ is selected from one or more than two of boron oxide, sodium carbonate, borax and antimony oxide;

the component D is CaO or Ca (OH)₂；

In the separant, the mass ratio of the component A, the component B, the component C and the component D is 100 (0.5-6): 0.6-3): 0.6-5.3): 1-2.1);

the release agent also contains NH₄Cl, said component A and said NH₄The mass ratio of Cl is 100 (1-2.1).

And (3) high-temperature annealing stage:

the cooling section includes in proper order:

(1) cooling in a cover when the temperature is 1200-500 ℃; wherein the protective gas is a mixed gas comprising nitrogen and hydrogen, and the volume percentage of the hydrogen in the mixed gas is more than 3 percent;

(2) cooling in a cover at the temperature of 500-200 ℃; wherein the protective gas is nitrogen;

(3) at a temperature of less than 200 ℃, the inner cover is uncovered for air cooling.

And (3) hot stretching and flattening stage:

adopts a four-section type cleaning process, which comprises the following steps in sequence:

(1) cleaning with water;

(2) acid washing is carried out by adopting a mixed solution containing 1-10% of sulfuric acid and 1-5% of nitric acid; wherein the pickling temperature is 50-80 ℃;

(3) washing with a mixture comprising water and ammonium citrate; wherein in the mixture, the mass concentration of the ammonium citrate is 0.5-5%;

(4) and washing with water.

Wherein, by mass percent, the casting blank comprises: 0.05-0.09% of C, 2.9-4.6% of Si, 0.05-0.20% of Mn, 0.005-0.020% of S, 0.0225-0.0325% of Als, 0.0045-0.0145% of N, 0.01-0.30% of Sn, 0.002-0.15% of Sb, 0.01-0.5% of Cr, 0.01-0.8% of Cu, and the balance of Fe and inevitable impurity elements.

The specific process parameters for the 8 test groups in this example are shown in tables 1 and 2:

table 1: some embodiments of the invention provide process parameters

Table 2: the components and parts by weight of the release agent provided by some embodiments of the invention

Wherein, the casting blank comprises the chemical components shown in the table 3 according to the mass percentage;

table 3: some embodiments of the invention provide a cast slab chemistry

Comparative example:

the comparative example adopts 8 comparison groups, and in comparison groups 1-8, the oriented silicon steel is prepared by adopting the relevant steps in 8 test groups of the embodiment of the invention, except that: the thickness of the oxide film is different, the adopted separant is different, and whether the hot stretching flattening and high-temperature annealing cooling section process is adopted is different.

Table 4: process parameters provided by the comparative group

Table 5: ingredients and parts by mass of release agent provided by comparison group

The oriented silicon steels prepared in the above examples and comparative examples were respectively subjected to performance tests, and the comparison results are shown in table 6:

table 6: the oriented silicon steels prepared in the examples and comparative examples were respectively subjected to performance tests

Note: level 1: uniform, bright and excellent, the oxide residual degree is less than or equal to 0.03g/m²No obvious steam mark, and the friction coefficient is less than 0.25; and 2, stage: uniform, bright and better, the oxide residual degree is less than or equal to 0.05g/m²The edge part is slightly steam-marked, and the friction coefficient is less than 0.35; and 3, level: is relatively uniformEven, local vapor marks, dark and lusterless luster, and oxide residual degree less than or equal to 0.07g/m²The friction coefficient is more than 0.45; 4, level: very uneven, dull and glowing, obvious vapor marks and oxide residue degree of more than 0.1g/m²The friction coefficient is more than 0.5.

From the above comparison of the above examples of the invention with comparative examples, it can be seen that: according to the preparation method of the non-bottom-layer oriented silicon steel, the defects of poor surface uniformity, poor finish, low yield, deteriorated magnetic performance and the like of the non-bottom-layer oriented silicon steel can be overcome by controlling the thickness of the oxide film, adopting the specific separant, adopting the specific hot-drawing flattening and high-temperature annealing cooling section process, so that the non-bottom-layer oriented silicon steel with uniform surface, excellent finish, good magnetic performance, small oxide residual degree, no obvious steam mark and small friction coefficient is obtained, and the qualified rate reaches over 90 percent, as shown in Table 6.

Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.