Non-oriented silicon steel and method for producing the same

Abstract

The application provides a non-oriented silicon steel and a production method thereof, and relates to the technical field of alloys. In the cold rolling process of the non-oriented silicon steel, the surface roughness of the work roll of a rolling mill is set in a trend of first decreasing and then increasing. Through fine control of the surface roughness of the roll in the rolling process, the surface roughness of the steel plate can be effectively controlled, the non-oriented silicon steel with excellent adhesion is produced, the adhesion between the coating and the steel plate is improved, the problem that the surface coating of the traditional non-oriented silicon steel is easy to fall off in the production process is solved, and the comprehensive performance of the non-oriented silicon steel is improved.

Description

Technical Field

[0001] This invention relates to the field of alloy technology, and more specifically to a non-oriented silicon steel and its production method. Background Technology

[0002] Non-oriented silicon steel is an important soft magnetic material, mainly used to manufacture stator and rotor cores for various motors and generators. During production, an insulating coating is applied to the surface of non-oriented silicon steel to reduce eddy current losses and iron losses. During the slitting and high-speed lamination processes of the finished silicon steel strip, a certain tension is applied. The clamping friction and curling process of the tension clamp can easily cause the coating on the surface of the non-oriented silicon steel to peel off. Coating peeling can lead to mold damage and a decrease in core performance. Summary of the Invention

[0003] The purpose of this invention is to provide a non-oriented silicon steel and its production method to solve the problem of easy peeling off of the insulating coating on the surface of silicon steel.

[0004] This invention provides a method for producing non-oriented silicon steel, comprising the following steps:

[0005] The chemical composition of the cold-rolled slab, by mass percentage, includes: Si: 0.50–2.25%, Mn: 0.20–1.0%, C ≤ 0.003%, P ≤ 0.04%, S ≤ 0.003%, with the remainder being Fe and unavoidable impurities;

[0006] According to the above chemical composition ratio, molten steel is obtained by smelting, and the molten steel is cast to form a cold-rolled slab.

[0007] The cold-rolled slab is cold-rolled to obtain a cold-rolled sheet. The target surface roughness of the cold-rolled slab is controlled to be 0.65-0.80 μm. In the rolling process, an acid continuous rolling mill is used for multi-pass rolling. The surface roughness of the work rolls of the mill is set according to the trend of first decreasing and then increasing. The surface roughness of the work rolls of the initial stand mill is controlled to be greater than the target surface roughness of the cold-rolled sheet. The surface roughness of the work rolls of the intermediate stand mill is controlled to be lower than the target surface roughness of the cold-rolled sheet. The surface roughness of the work rolls of the final stand mill is controlled to be greater than the target surface roughness of the cold-rolled sheet.

[0008] Annealing is performed after rolling;

[0009] After annealing, pickling is performed to remove the oxide layer on the surface of the steel plate;

[0010] An insulating layer is coated on the surface of the steel plate, and the final non-oriented silicon steel plate has a coating adhesion grade A ratio of >97%, iron loss ≤3.2W / kg, and magnetic induction ≥1.68T.

[0011] As a further improvement of the present invention, the chemical composition of the cold-rolled slab also includes one or more of Al, Ni, Cu, Cr, Sn, Sb, and Nb, and the above elements satisfy 0.3% ≤ (Al + Ni + Cu + Cr + Sn + Sb + Nb) ≤ 1% by mass percentage.

[0012] As a further improvement of the present invention, the step of cold rolling the cold-rolled slab to obtain a cold-rolled sheet further includes:

[0013] The surface roughness range of the initial stand mill work rolls is controlled to be no greater than 150% of the target surface roughness of the cold-rolled sheet, the surface roughness range of the intermediate stand work rolls is controlled to be no greater than 85% of the target surface roughness of the cold-rolled sheet, and the surface roughness range of the final stand work rolls is controlled to be no greater than 115% of the target surface roughness of the cold-rolled sheet.

[0014] As a further improvement of the present invention, the step of cold rolling the cold-rolled slab to obtain a cold-rolled sheet further includes:

[0015] During the rolling process, the total reduction rate is controlled at 84-87%, and the reduction rate of different stands gradually decreases.

[0016] As a further improvement of the present invention, the step of cold rolling the cold-rolled slab to obtain a cold-rolled sheet specifically includes:

[0017] The rolling process is carried out in 5 passes using a continuous rolling mill, consisting of 1 to 5 stands. The diameter of the work rolls is controlled within the range of 390 to 450 mm. The roughness value of the work rolls in stand 1 is controlled within the range of 0.90 to 1.20 μm, the roughness value of the work rolls in stands 2 to 4 is controlled within the range of 0.40 to 0.70 μm, and the roughness value of the work rolls in stand 5 is controlled within the range of 0.75 to 0.90 μm.

[0018] As a further improvement of the present invention, the step of cold rolling the cold-rolled slab to obtain a cold-rolled sheet further includes:

[0019] The total rolling reduction rate is controlled at 84-87%, the reduction rate of the 1st stand is controlled at 30-36%, the reduction rate of the 5th stand is controlled at 10-15%, and the reduction rate of the 1st to 5th stands gradually decreases.

[0020] As a further improvement of the present invention, the annealing treatment after rolling specifically includes:

[0021] Annealing is performed under a mixture of H2 and N2 gas or under all H2 conditions. When using a mixture of H2 and N2 gas, the volume content of H2 is not less than 50%. The annealing temperature is controlled at 800–950℃ and held at 800–950℃ for 180–300 seconds.

[0022] As a further improvement of the present invention, the pickling after annealing to remove the oxide layer on the surface of the steel plate specifically includes:

[0023] Pickling is performed using a mixed acid of phosphoric acid, oxalic acid, and trisodium phosphate to remove the oxide layer from the surface of the steel plate. In the mixed acid, the concentration of phosphoric acid ranges from 50% to 75%, the concentration of oxalic acid ranges from 0.5% to 1%, and the concentration of trisodium phosphate ranges from 20% to 30%. The mass ratio of phosphoric acid, oxalic acid, and trisodium phosphate is 20:1:4. The pickling temperature is controlled at 30 to 50°C, and the pickling time is controlled at 5 to 20 seconds.

[0024] As a further improvement of the present invention, the coating of the insulating layer on the surface of the steel plate specifically includes:

[0025] A chromium-containing coating or an environmentally friendly coating is applied to the surface of the steel plate. The thickness of the coating on one side is controlled to be 0.05–2.0 μm, the curing temperature of the coating is controlled to be 400–620℃, and the curing time of the coating is 30–180 s.

[0026] As a further improvement of the present invention, the method further includes the step of: finishing the steel plate to adjust it into a non-oriented silicon steel plate with a width of 1240 mm and a thickness of 0.35 mm.

[0027] The present invention also provides a non-oriented silicon steel, wherein the surface roughness of the non-oriented silicon steel is 0.65-0.80μm, the proportion of coating adhesion grade A is >97%, the iron loss is ≤3.2W / kg, and the magnetic induction is ≥1.68T.

[0028] The beneficial effects of this invention are as follows: This invention proposes a non-oriented silicon steel and its production method. During the cold rolling process, the surface roughness of the working rolls of the rolling mill is set according to the trend of first decreasing and then increasing. By precisely controlling the surface roughness of the rolls during the rolling process, the surface roughness of the steel plate can be effectively controlled, and non-oriented silicon steel with excellent adhesion can be produced. This improves the adhesion between the coating and the steel plate, thereby solving the problem of easy peeling of the surface coating in the production process of traditional non-oriented silicon steel and improving the comprehensive performance of non-oriented silicon steel. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the steps in a method for producing non-oriented silicon steel according to one embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] This embodiment provides a non-oriented silicon steel and its production method. By precisely controlling the surface roughness of the rolls during the rolling process, the surface roughness of the steel plate can be effectively controlled, resulting in non-oriented silicon steel with excellent adhesion. This improves the adhesion between the coating and the steel plate, thereby solving the problem of easy peeling of the surface coating in the production process of traditional non-oriented silicon steel and enhancing the overall performance of non-oriented silicon steel.

[0032] In this embodiment, the chemical composition of the non-oriented silicon steel is the same as that of conventional non-oriented silicon steel, mainly including Si and Mn, with controlled contents of C, P, and S. Specifically, by mass percentage, it includes: Si: 0.50–2.25%, Mn: 0.20–1.0%, C ≤ 0.003%, P ≤ 0.04%, S ≤ 0.003%, with the remainder being Fe and unavoidable impurities.

[0033] In non-oriented silicon steel, the addition of silicon (Si) significantly increases the resistivity of the steel. Since eddy current loss is inversely proportional to the resistivity of the material, it can reduce eddy current loss. Although Si reduces eddy current loss, it also reduces the magnetic permeability and magnetic flux density. Therefore, it is necessary to balance the Si content to optimize the relationship between iron loss and magnetic flux density. The addition of Si can also shrink the γ-phase region of the steel. With high silicon content, decarburization is easier during steel annealing, thereby reducing residual stress and optimizing the microstructure. Furthermore, silicon can improve the strength of the solid solution and the cold work hardening rate in the steel, thus enabling the steel to obtain better mechanical properties during cold rolling, which is beneficial to improving the quality of the final product. However, the addition of Si significantly reduces the thermal conductivity of the steel, which may lead to stress concentration due to temperature gradients between the inside and outside of the material, making it prone to cracking. Therefore, in this embodiment, the mass content of Si is controlled to be 0.50–2.25%.

[0034] Mn can act as a deoxidizer and desulfurizer. As an effective deoxidizer, Mn can form stable MnO with oxygen in steel, reducing oxygen inclusions. Simultaneously, Mn has a strong affinity for sulfur (S), forming MnS, reducing the adverse effects of S in steel, particularly alleviating S-induced hot brittleness. Mn can expand the γ-phase region in steel, lower the eutectoid temperature, and improve the mechanical properties of steel by reducing the carbon content in pearlite, thereby affecting the phase transformation and microstructure. Furthermore, the formation of MnS prevents hot brittleness caused by low-melting-point FeS along grain boundaries, which is beneficial for improving the plasticity and microstructure of steel, and also has a positive effect on improving magnetic properties. However, the presence of MnS inclusions may affect the properties of the steel; therefore, in this embodiment, the mass content of Mn is controlled at 0.20–1.0%.

[0035] Furthermore, the chemical composition of the cold-rolled slab also includes one or more of Al, Ni, Cu, Cr, Sn, Sb, and Nb, and the above elements, by mass percentage, satisfy 0.3% ≤ (Al + Ni + Cu + Cr + Sn + Sb + Nb) ≤ 1%. The performance of silicon steel is enhanced by adding a small amount of strengthening elements, while avoiding any impact on magnetic properties.

[0036] Al is an effective deoxidizer that can reduce the oxygen content in steel, thereby reducing oxide inclusions. Furthermore, Al increases the resistivity of steel, which helps reduce eddy current losses and improves the magnetic properties of the steel.

[0037] Ni can improve the strength and toughness of steel, and also helps to enhance its magnetic properties. Furthermore, Ni can improve the overall mechanical properties of steel, making it more suitable for manufacturing high-performance electrical steel.

[0038] Cu can enhance the corrosion resistance of steel and, to some extent, improve its electrical conductivity. While improved conductivity is detrimental to reducing the magnetic properties of steel, an appropriate amount of copper can play a balancing role in improving corrosion resistance and enhancing mechanical properties.

[0039] Cr is mainly used to improve the oxidation and corrosion resistance of steel, and to enhance the stability of steel at high temperatures.

[0040] Sn can improve the corrosion resistance of steel, especially its resistance to sulfides.

[0041] Sb can increase the strength of steel, and at the same time, it forms stable compounds with sulfur, which helps to reduce the brittleness caused by sulfur in steel.

[0042] By refining the grain size, nitrogen (Nb) can improve the strength and toughness of steel and enhance its magnetic properties, thereby reducing iron loss.

[0043] like Figure 1As shown, the present invention also provides a method for producing the aforementioned steel plate. In this embodiment, the production method includes the following steps:

[0044] S1: According to the above chemical composition ratio, molten steel is obtained by smelting, and the molten steel is cast to form a cold-rolled slab.

[0045] S2: Cold-rolled slabs are cold-rolled to obtain cold-rolled sheets. The target surface roughness of the cold-rolled slabs is controlled to be 0.65-0.80 μm. In the rolling process, acid continuous rolling mills are used for multi-pass rolling. The surface roughness of the work rolls of the mills is set according to the trend of first decreasing and then increasing. The surface roughness of the work rolls of the initial stand mills is controlled to be greater than the target surface roughness of the cold-rolled sheets. The surface roughness of the work rolls of the intermediate stand mills is controlled to be lower than the target surface roughness of the cold-rolled sheets. The surface roughness of the work rolls of the final stand mills is controlled to be greater than the target surface roughness of the cold-rolled sheets.

[0046] S3: Annealing treatment is performed after rolling.

[0047] S4: After annealing, pickling is performed to remove the oxide layer on the surface of the steel plate.

[0048] S5: Coat the surface of the steel plate with an insulating layer.

[0049] In step S1, cold-rolled slabs are obtained through conventional smelting and casting. Various raw materials, including pig iron, scrap steel, alloying elements, deoxidizers, and desulfurizers, are prepared. These raw materials are charged into a steelmaking furnace in proportion and melted using an electric arc furnace, induction furnace, or converter. During the melting process, the timing of alloying element addition is controlled by adjusting the heating temperature and time to ensure that the alloying elements are fully dissolved and evenly distributed in the molten steel. During the melting process, deoxidizers and desulfurizers are added to the molten steel, reacting with oxygen and sulfur to generate oxides and sulfide inclusions, which are subsequently removed through slag treatment.

[0050] The molten steel is continuously cast, and by controlling the cooling rate and casting rate, the molten steel solidifies into a solid slab.

[0051] In step S2, the target surface roughness of the cold-rolled slab after rolling is controlled within the range of 0.65–0.80 μm. Maintaining a surface roughness within this range increases the contact area between the coating and the steel plate, providing more mechanical anchoring points, thereby improving coating adhesion and ensuring coating uniformity and durability. Furthermore, precise control of surface roughness can also reduce surface defects such as scratches and pits to some extent, thus improving the overall quality and appearance of the final product.

[0052] The rolling process employs a pickling continuous rolling process, which involves removing oxide scale and other contaminants from the steel plate surface through pickling before continuous cold rolling. Pickling involves immersing the steel plate in an acidic solution containing dilute sulfuric acid or hydrochloric acid, removing the oxide scale from the steel plate surface through a chemical reaction, cleaning the steel plate surface, and providing a clean and smooth surface for the subsequent cold rolling process.

[0053] During the rolling process, rolling mills that utilize variations in the surface roughness of the work rolls have the following effects:

[0054] The initial frame roll surface roughness is relatively high. This high roll surface roughness helps to form a certain micro-uneven structure on the surface of the cold-rolled slab, which is beneficial to the adhesion of coating materials in subsequent processes and can also effectively reduce the initial defects on the material surface, providing a good foundation for the next processing step.

[0055] The surface roughness of the intermediate stand rolls is reduced. By reducing the surface roughness of the rolls in the intermediate rolling stage, the surface of the steel plate is further refined, surface defects are reduced, and surface flatness is improved. This helps to improve the overall quality of the steel plate and ensures that the surface of the steel plate has good adaptability to subsequent coating processes.

[0056] Finally, the surface roughness of the frame rollers is increased again to ensure that the steel plate surface has sufficient micro-uneven structure to enhance the mechanical anchoring effect of subsequent coatings, optimize coating adhesion, and improve coating uniformity and durability.

[0057] Using the above-mentioned roll surface roughness control strategy helps to achieve precise management of the steel plate surface quality during the cold rolling process. Through precise control at different stages, the coating adhesion requirements are met, while the flatness and excellent electromagnetic properties of the steel plate are guaranteed.

[0058] Furthermore, in this embodiment, the surface roughness range of the initial stand mill work rolls is controlled to be no greater than 150% of the target surface roughness of the cold-rolled sheet, the surface roughness range of the intermediate stand work rolls is controlled to be no greater than 85% of the target surface roughness of the cold-rolled sheet, and the surface roughness of the final stand work rolls is controlled to be no greater than 115% of the target surface roughness of the cold-rolled sheet.

[0059] Specifically, in this embodiment, a continuous rolling mill is used for 5 passes, namely 1 to 5 stands. The diameter of the work rolls of the mill is controlled within the range of 390 to 450 mm. The roughness value of the work rolls of the 1st stand is controlled within the range of 0.90 to 1.20 μm. The roughness value of the work rolls of the 2nd to 4th stands is controlled within the range of 0.40 to 0.70 μm. The roughness value of the work rolls of the 5th stand is controlled within the range of 0.75 to 0.90 μm.

[0060] In other embodiments of the present invention, the roughness range of the work rolls and the number of rolling mills can also be adaptively adjusted according to the type of steel being processed and the type of coating film.

[0061] Furthermore, the rolling process also includes: during the rolling process, the total rolling reduction rate is controlled at 84-87%, and the reduction rate of different stand rolling mills is gradually reduced.

[0062] Specifically, in this embodiment, the total rolling reduction rate is controlled at 84-87%, the reduction rate of the 1st stand is controlled at 30-36%, the reduction rate of the 5th stand is controlled at 10-15%, and the reduction rate of the 1st to 5th stands gradually decreases.

[0063] By setting the total reduction rate between 84% and 87%, it is ensured that the steel plate undergoes sufficient plastic deformation throughout the rolling process, which helps to refine the grains, optimize the microstructure of the material, and achieve the final required specifications.

[0064] Starting with a higher reduction rate at the first stand and gradually decreasing to a lower reduction rate at the fifth stand, the progressively decreasing reduction rate helps to smoother material deformation, reduces internal stress and surface defects that may occur during rolling, and improves the quality of the final product. The higher reduction rate in the initial stage facilitates rapid thinning and breaks up the as-cast structure, while the subsequent progressively decreasing reduction rate helps to refine the surface quality, making the steel plate's thickness and surface roughness more uniform, providing a good foundation for subsequent coating processes.

[0065] By controlling the rolling reduction rate, the grain size and orientation of steel can be effectively controlled, thereby reducing hysteresis loss and eddy current loss and improving the magnetic permeability of the material. Furthermore, by rationally allocating the deformation amount in each pass, the stability and efficiency of rolling can be improved while ensuring product performance.

[0066] In step S3, the rolled steel sheet is annealed, specifically including:

[0067] Annealing is performed under a mixture of H2 and N2 gas or under all H2 conditions. When using a mixture of H2 and N2 gas, the volume content of H2 is not less than 50%. The annealing temperature is controlled at 800–950℃ and held at 800–950℃ for 180–300 seconds.

[0068] Using hydrogen as the annealing atmosphere, its strong reducing properties effectively remove oxides from the material's surface and interior, preventing further oxidation of the metal at high temperatures. Nitrogen is mixed in to dilute the hydrogen, controlling the atmosphere's reducing power and cost. Controlling the annealing temperature and holding time promotes recrystallization of the metal grains, refining the grain structure. Refined grains help reduce hysteresis loss and improve magnetic permeability. Annealing also eliminates internal stresses generated during cold rolling, reducing material brittleness, improving plasticity and toughness, and resulting in better performance stability during subsequent processing and use.

[0069] In step S4, in this embodiment, a mixed acid of phosphoric acid, oxalic acid, and trisodium phosphate is used for pickling to remove the oxide layer on the surface of the steel plate. In the mixed acid, the concentration of phosphoric acid ranges from 50 to 75%, the concentration of oxalic acid ranges from 0.5 to 1%, and the concentration of trisodium phosphate ranges from 20 to 30%. The mass ratio between phosphoric acid, oxalic acid, and trisodium phosphate is 20:1:4. The pickling temperature is controlled at 30 to 50°C, and the pickling time is controlled at 5 to 20 seconds.

[0070] In the aforementioned pickling agents, phosphoric acid and oxalic acid effectively remove the oxide layer formed on the steel plate surface during cold rolling and heat treatment, preventing any impact on coating adhesion. Adding trisodium phosphate to the mixed acid as a buffer prevents excessive corrosion of the metal during pickling, protecting the steel plate substrate from damage. Trisodium phosphate also neutralizes residual acidity, reducing the stress on subsequent cleaning processes.

[0071] By precisely controlling the concentration and mass ratio of phosphoric acid, oxalic acid, and trisodium phosphate, the pickling speed and efficiency can be adjusted, ensuring that the pickling process effectively removes the oxide layer while maintaining high production efficiency. Controlling the pickling temperature and time can optimize pickling efficiency and avoid material damage caused by excessively high temperatures or prolonged times.

[0072] In other embodiments of the present invention, other pickling agents may also be used, as long as they can achieve the effect of pickling the oxide layer.

[0073] Step S5 specifically includes:

[0074] A chromium-containing coating or an environmentally friendly coating is applied to the surface of the steel plate. The thickness of the coating on one side is controlled to be 0.05–2.0 μm, the curing temperature of the coating is controlled to be 400–620℃, and the curing time of the coating is 30–180 s.

[0075] The coating thickness is controlled between 0.05 and 2.0 μm to ensure that the coating can function effectively without adversely affecting the material's flexibility and processing performance. An excessively thick coating may affect the magnetic properties of the steel plate, while an excessively thin coating may not provide sufficient protection and insulation.

[0076] By controlling the curing temperature between 400 and 620°C and the curing holding time between 30 and 180 seconds, the uniformity and adhesion of the coating can be ensured, while maintaining the performance of the coating.

[0077] After coating the steel plate, it is finished to obtain a non-oriented silicon steel plate with a width of 1240mm and a thickness of 0.35mm, meeting the specifications. According to GB / T2522-2017 standard, the final non-oriented silicon steel has a coating adhesion grade A ratio >97%, and according to GB / T 39042-2020 standard, the iron loss of the non-oriented silicon steel is ≤3.2W / kg, and the magnetic induction is ≥1.68T.

[0078] This embodiment also provides a non-oriented silicon steel with a surface roughness of 0.65 to 0.80 μm. According to GB / T 2522-2017 standard, the proportion of coating adhesion grade A of the non-oriented silicon steel is >97%. According to GB / T 39042-2020 standard, the iron loss of the non-oriented silicon steel is ≤3.2 W / kg, and the magnetic induction of the non-oriented silicon steel is ≥1.68 T.

[0079] In summary, this solution proposes a method for producing non-oriented silicon steel. During the cold rolling process, the surface roughness of the working rolls of the rolling mill is set to decrease first and then increase. By precisely controlling the surface roughness of the rolls during the rolling process, the surface roughness of the steel plate can be effectively controlled, resulting in non-oriented silicon steel with excellent adhesion. This improves the adhesion between the coating and the steel plate, thereby solving the problem of easy coating peeling during the production of traditional non-oriented silicon steel and enhancing the overall performance of the non-oriented silicon steel.

[0080] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0081] The detailed descriptions listed above are merely specific descriptions of feasible implementations of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent implementations or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing non-oriented silicon steel, characterized in that, The chemical composition of the non-oriented silicon steel, by mass percentage, includes: Si: 0.50~2.25%, Mn: 0.20~1.0%, C≤0.003%, P≤0.04%, S≤0.003%, with the remainder being Fe and unavoidable impurities; The production method includes the following steps: According to the above chemical composition ratio, molten steel is obtained by smelting, and the molten steel is cast to form a cold-rolled slab. The cold-rolled slab is cold-rolled to obtain a cold-rolled sheet. The target surface roughness of the cold-rolled slab is controlled to be 0.65~0.80μm. In the rolling process, a continuous acid rolling mill is used for multi-pass rolling. The surface roughness of the work rolls of the mill is set according to the trend of first decreasing and then increasing. The surface roughness of the work rolls of the initial stand mill is controlled to be greater than the target surface roughness of the cold-rolled sheet but not greater than 150% of the target surface roughness of the cold-rolled sheet. The surface roughness of the work rolls of the intermediate stand mill is controlled to be lower than the target surface roughness of the cold-rolled sheet but not greater than 85% of the target surface roughness of the cold-rolled sheet. The surface roughness of the work rolls of the final stand mill is controlled to be greater than the target surface roughness of the cold-rolled sheet but not greater than 115% of the target surface roughness of the cold-rolled sheet. Annealing is performed after rolling; After annealing, pickling is performed to remove the oxide layer on the surface of the steel plate; An insulating layer is coated on the surface of the steel plate, and the final non-oriented silicon steel plate has a coating adhesion grade A ratio of >97%, iron loss ≤3.2W / kg, and magnetic induction ≥1.68T.

2. The method for producing non-oriented silicon steel according to claim 1, characterized in that, The chemical composition of the cold-rolled slab also includes one or more of Al, Ni, Cu, Cr, Sn, Sb, and Nb, and satisfies 0.3%≤(Al+Ni+Cu+Cr+Sn+Sb+Nb)≤1% by mass percentage.

3. The method for producing non-oriented silicon steel according to claim 1, characterized in that, The step of cold rolling the cold-rolled slab to obtain a cold-rolled sheet further includes: During the rolling process, the total reduction rate is controlled at 84-87%, and the reduction rate of different stands gradually decreases.

4. The method for producing non-oriented silicon steel according to claim 1, characterized in that, The process of cold rolling the cold-rolled slab to obtain a cold-rolled sheet specifically includes: The rolling process is carried out in 5 passes using a continuous rolling mill, consisting of 1 to 5 stands. The diameter of the work rolls is controlled within the range of 390 to 450 mm. The roughness value of the work rolls in stand 1 is controlled within the range of 0.90 to 1.20 μm, the roughness value of the work rolls in stands 2 to 4 is controlled within the range of 0.40 to 0.70 μm, and the roughness value of the work rolls in stand 5 is controlled within the range of 0.75 to 0.90 μm.

5. The method for producing non-oriented silicon steel according to claim 4, characterized in that, The step of cold rolling the cold-rolled slab to obtain a cold-rolled sheet further includes: The total rolling reduction rate is controlled at 84-87%, the reduction rate of the 1st stand is controlled at 30-36%, the reduction rate of the 5th stand is controlled at 10-15%, and the reduction rate of the 1st to 5th stands gradually decreases.

6. The method for producing non-oriented silicon steel according to claim 1, characterized in that, The annealing process following rolling specifically includes: Annealing is performed under a mixture of H2 and N2 or under all H2 conditions. When using a mixture of H2 and N2, the volume content of H2 is not less than 50%. The annealing temperature is controlled at 800~950℃ and held at 800~950℃ for 180~300s.

7. The method for producing non-oriented silicon steel according to claim 1, characterized in that, The pickling process following annealing removes the oxide layer from the steel plate surface, specifically including: Pickling is performed using a mixed acid of phosphoric acid, oxalic acid, and trisodium phosphate to remove the oxide layer from the surface of the steel plate. In the mixed acid, the concentration of phosphoric acid ranges from 50 to 75%, the concentration of oxalic acid ranges from 0.5 to 1%, and the concentration of trisodium phosphate ranges from 20 to 30%. The mass ratio of phosphoric acid, oxalic acid, and trisodium phosphate is 20:1:

4. The pickling temperature is controlled at 30 to 50°C, and the pickling time is controlled at 5 to 20 seconds.

8. The method for producing non-oriented silicon steel according to claim 1, characterized in that, The process of coating an insulating layer on the surface of the steel plate specifically includes: A chromium-containing coating or an environmentally friendly coating is applied to the surface of the steel plate. The thickness of the coating on one side is controlled to be 0.05~2.0μm, the curing temperature of the coating is controlled to be 400~620℃, and the curing time of the coating is 30~180s.

9. The method for producing non-oriented silicon steel according to claim 1, characterized in that, It also includes the step of finishing the steel plate and adjusting it to a non-oriented silicon steel plate with a width of 1240mm and a thickness of 0.35mm.

10. A non-oriented silicon steel, characterized in that, The non-oriented silicon steel is prepared by the non-oriented silicon steel production method as described in any one of claims 1 to 9. The surface roughness of the non-oriented silicon steel is 0.65~0.80μm, the proportion of coating adhesion grade A is >97%, the iron loss is ≤3.2W / kg, and the magnetic induction is ≥1.68T.

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