A control method for improving the consistency of surface notch quality of oriented silicon steel

Abstract

The application discloses a control method for improving surface scratch quality consistency of oriented silicon steel, which comprises the following steps: S1, performing degreasing and pickling combined pretreatment on the plate; S2, performing isolating agent coating treatment on the plate; S3, performing high-temperature annealing treatment on the plate; S4, performing post-treatment on the plate; in S1, the degreasing and pickling combined pretreatment comprises degreasing, pickling, rinsing and drying which are sequentially performed, wherein: the degreasing temperature is controlled to be 60-80 DEG C, and the degreasing time is controlled to be 3-5 min; the plate is pickled by using a dilute hydrochloric acid solution with a concentration of 5-8%, and the pickling temperature is controlled to be 40-50 DEG C, and the pickling time is controlled to be 2-4 min; the plate is rinsed by using high-pressure water with a pressure of 10-15 MPa; and the drying temperature is controlled to be 80-100 DEG C. The application can eliminate surface scratch mark defects of the finished oriented silicon steel and improve the surface quality consistency of the oriented silicon steel.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for controlling the consistency of surface marking quality in grain-oriented silicon steel. Background Technology

[0002] Grain-oriented silicon steel is a core material for power equipment such as power transformers and large motors. Its surface quality directly affects the insulation performance, processing performance, and operational stability of the equipment. The scoring process is one of the key processes for improving the magnetic properties of grain-oriented silicon steel. However, in actual production, uneven distribution of scoring marks often appears on the surface of finished grain-oriented silicon steel, severely reducing the product's surface quality and market competitiveness.

[0003] In actual production, a defect called "scratching marks" often appears on the surface of finished grain-oriented silicon steel, severely affecting the product's appearance and market competitiveness. This defect is not directly caused by the subsequent laser scratching process; its root cause lies in the unevenness of the magnesium silicate underlayer formed after high-temperature annealing and the final coated insulating coating. The uniformity of the underlayer, as the substrate for the insulating coating, directly determines the forming quality and thickness distribution of the insulating coating. Uneven growth of the underlayer will lead to localized variations in the thickness and adhesion of the insulating coating, ultimately manifesting as scratch marks of varying brightness and depth on the finished product surface.

[0004] Therefore, there is an urgent need to develop a control method that starts from the source, optimizes the process to achieve uniform generation of the oriented silicon steel underlayer and uniform forming of the glass film, and completely eliminates surface scratch marks, so as to adapt to existing production lines and take into account both process feasibility and production economy. Summary of the Invention

[0005] In order to solve all or part of the above problems, the purpose of this invention is to provide a method for controlling the quality consistency of surface scratches on grain-oriented silicon steel, which can eliminate surface scratch defects of finished grain-oriented silicon steel and improve the surface quality consistency of grain-oriented silicon steel.

[0006] This invention provides a method for controlling the consistency of surface scoring quality in grain-oriented silicon steel, comprising the following steps: S1, the board undergoes a combined pretreatment of degreasing and pickling; S2, apply a release agent coating to the board; S3, high-temperature annealing treatment of the board material; S4, post-processing of the board material; In S1, the combined degreasing and pickling pretreatment includes sequential degreasing, pickling, rinsing, and drying, wherein: Control the defatting temperature to 60-80℃ and the defatting time to 3-5 minutes; The board is pickled using a 5-8% dilute hydrochloric acid solution, and the pickling temperature is controlled at 40-50℃ and the pickling time is 2-4 minutes. The boards are rinsed with high-pressure water at 10-15MPa; Control the drying temperature to 80-100℃.

[0007] Optionally, in S2, magnesium oxide release agent and deionized water are mixed to form a suspension with a solid content of 30-40%, and ultrasonically dispersed for 30-60 minutes. Then, the suspension is uniformly coated on the surface of the board using a roller coating method, and the board is dried.

[0008] Optionally, in S2, the magnesium oxide separating agent has the following mass percentage composition: MgO ≥ 95%, SiO2 ≤ 2.0%, CaO ≤ 1.0%, with the balance being unavoidable impurities.

[0009] Optionally, in S2, the coating roller pressure is controlled to be 0.3-0.5MPa, the coating speed is controlled to be 10-15m / min, the thickness of the release agent layer on the surface of the board after drying is controlled to be 10-15μm, and the thickness deviation of the release agent layer at each position on the surface of the board is ≤±1μm.

[0010] Optionally, in S2, the board is dried at 60-80°C for 10-15 minutes to form a dense MgO coating layer.

[0011] Optionally, in S3, the plate is sent into a continuous annealing furnace for high-temperature secondary recrystallization annealing. The plate is heated at a rate of 5-8℃ / min and held at 800-850℃ for 2-3 hours. The temperature is then increased to 1100-1150℃ and held for 10-15 hours. Finally, the plate is cooled to below 600℃ at a rate of 3-5℃ / min before being removed from the furnace.

[0012] Optionally, in S3, the plate annealing process is carried out in a mixed protective atmosphere of N2 and H2, and the volume percentage of H2 is controlled at 20-30% and the oxygen potential in the furnace is 10. -18 -10 -16 Pa.

[0013] Optionally, in S4, the board is lightly acid-washed, rinsed with deionized water, then an insulating coating is applied to the surface of the board, and the board is cured.

[0014] Optionally, in S4, the board is lightly acid-washed for 1-2 minutes with a 2-3% dilute nitric acid solution to remove free MgO from the surface of the board.

[0015] Optionally, in S4, the board is cured at 200-250°C for 10-15 minutes to form a uniform, insulating surface coating with tensile stress on the board surface.

[0016] As can be seen from the above technical solution, the method for controlling the consistency of surface scoring quality of grain-oriented silicon steel provided by the present invention has the following advantages: This control method addresses the root cause of scratch marks by optimizing the entire process, including surface pretreatment, release agent optimization, annealing process control, and glass film post-treatment. This achieves uniform generation of the bottom layer of oriented silicon steel and uniform forming of the glass film, thereby eliminating scratch mark defects on the surface of the finished oriented silicon steel and improving the surface quality consistency of the oriented silicon steel.

[0017] Other features and advantages of the present invention will be set forth in the following description. Attached Figure Description

[0018] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation on the technical solutions of the present invention.

[0019] Figure 1 This is a flowchart illustrating an embodiment of the present invention; Figure 2 This is a comparative product morphology diagram in an embodiment of the present invention; Figure 3 This is a product morphology diagram of a specific embodiment of the present invention; Figure 4 This is a bottom cross-sectional view of a comparative example in an embodiment of the present invention; Figure 5 This is a bottom cross-sectional view of a specific embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be arbitrarily combined with each other.

[0021] like Figures 1-5 The illustration shows an embodiment of the present invention, which discloses a method for controlling the consistency of surface scoring quality in grain-oriented silicon steel, comprising the following steps: S1, the board undergoes a combined pretreatment of degreasing and pickling; S2, apply a release agent coating to the board; S3, high-temperature annealing treatment of the board material; S4, post-processing of the board material.

[0022] The method for improving the consistency of surface scratch quality in this embodiment achieves uniform generation of the oriented silicon steel substrate and uniform forming of the glass film through coordinated optimization of the entire process, including surface pretreatment, release agent optimization, annealing process control, and glass film post-treatment. This completely eliminates surface scratch defects and improves the consistency of the oriented silicon steel surface quality. Furthermore, the process scheme of this invention is compatible with existing oriented silicon steel production lines, requiring no additional core production equipment. The process adjustment is simple, and its industrial application feasibility is high. While improving product quality, it does not increase production costs or affect production efficiency.

[0023] The sheet material in this embodiment is a decarburized annealed plate of oriented silicon steel, which is an intermediate product obtained after hot rolling, normalizing, cold rolling and decarburizing annealing processes.

[0024] In step S1, the combined degreasing and pickling pretreatment includes sequential degreasing, pickling, rinsing, and drying. The degreasing temperature is controlled at 60-80℃ and the degreasing time is 3-5 minutes. The board is pickled using a 5-8% dilute hydrochloric acid solution, with the pickling temperature controlled at 40-50℃ and the pickling time controlled at 2-4 minutes. Subsequently, the board is rinsed with high-pressure water at 10-15 MPa and dried with hot air at 80-100℃.

[0025] This step aims to thoroughly remove oil stains and thin oxide layers formed during annealing from the board surface, and to control the surface roughness Ra within a uniform range of 0.3-0.5 μm, providing a clean and activated substrate for subsequent uniform application of the release agent.

[0026] In step S2, a high-purity magnesium oxide isolating agent is prepared, with the following mass percentage composition: MgO ≥ 95%, SiO2 ≤ 2.0%, CaO ≤ 1.0%, and the balance being unavoidable impurities. Subsequently, the magnesium oxide isolating agent and deionized water are mixed to prepare a suspension with a solid content of 30-40%, and ultrasonically dispersed for 30-60 minutes to ensure uniform dispersion.

[0027] Next, the suspension is uniformly coated onto the board surface using a roller coating method, with the coating roller pressure controlled at 0.3-0.5 MPa and the coating speed at 10-15 m / min to ensure uniform wet film thickness. Simultaneously, the thickness of the release agent layer on the board surface after drying is controlled to be 10-15 μm, with a thickness deviation of ≤±1 μm at different locations on the board surface. Subsequently, the board is dried at 60-80℃ for 10-15 minutes to form a dense MgO adhesion layer.

[0028] In S3, the sheet is fed into a continuous annealing furnace for high-temperature secondary recrystallization annealing. The sheet is controlled to be heated at a rate of 5-8 °C / min, held at 800-850 °C for 2-3 hours, continuously heated to 1100-1150 °C and held for 10-15 hours, and then cooled to below 600 °C at a rate of 3-5 °C / min before being taken out of the furnace.

[0029] The entire annealing process of the sheet is carried out in a mixed protective atmosphere of N2 and H2, and the volume percentage of H2 is controlled to be 20-30%, and the oxygen potential in the furnace is 10 -18 -10 -16 Pa. This step is the key to forming a uniform magnesium silicate bottom layer. By controlling the heating rate and oxygen potential, the secondary recrystallization process of the steel sheet and the chemical reaction rate between MgO and the silicon of the substrate are synchronously regulated to ensure that the bottom layer grows uniformly and densely at each position of the steel sheet.

[0030] In S4, after high-temperature annealing, a magnesium silicate bottom layer is formed on the surface of the sheet and unreacted free MgO is attached. First, the sheet surface is lightly pickled with a dilute nitric acid solution with a concentration of 2-3% for 1-2 minutes to remove the free MgO, and then rinsed clean with deionized water after pickling.

[0031] Subsequently, an insulating coating (such as a phosphate-based tension coating) is coated on the clean bottom layer surface and cured at 200-250 °C for 10-15 minutes. This step forms a final uniform, insulating and stress-bearing surface coating, and its uniformity directly depends on the smoothness and uniformity of the bottom layer.

[0032] Finally, the surface quality of the final product is inspected. Visual inspection is combined with a surface roughness meter for inspection. It is required that there are no visible scratch marks on the surface of the finished product, and the deviation of the surface roughness Ra at each position on the sheet surface ≤ ±0.1 μm, which is considered qualified.

[0033] To illustrate the present application more clearly, the following are specific examples and comparative examples: Example 1 S1, the sheet is pretreated by combining degreasing and pickling: The degreasing temperature is controlled at 60 °C, the degreasing time is 3 min, the sheet is pickled with a dilute hydrochloric acid solution with a concentration of 5%, and the pickling temperature is controlled at 40 °C and the pickling time is 2 min. Subsequently, the sheet is rinsed with high-pressure water at 10 MPa and dried with hot air at 80 °C. The surface roughness Ra of the sheet is 0.3.

[0034] S2, the sheet is coated with an isolating agent: A high-purity magnesium oxide release agent with a MgO content of 95% was prepared and mixed with deionized water to form a suspension with a solid content of 30%. This suspension was then ultrasonically dispersed for 30 minutes. Next, the suspension was uniformly coated onto the surface of the board using a roller coating method, with the coating roller pressure controlled at 0.3 MPa and the coating speed at 10 m / min. Simultaneously, the thickness of the release agent layer on the board surface after drying was controlled at 10 μm, and the board was dried at 60℃ for 10 minutes.

[0035] S3, high-temperature annealing treatment of the board material: The sheet material was fed into a continuous annealing furnace for high-temperature secondary recrystallization annealing. The temperature was increased at a rate of 5°C / min and held at 800°C for 2 hours. The temperature was then increased to 1100°C and held for 10 hours, followed by a decrease to 600°C at a rate of 3°C / min before being removed from the furnace. Simultaneously, the entire annealing process was carried out in a mixed protective atmosphere of N2 and H2, with the H2 volume percentage controlled at 20% and the oxygen potential in the furnace at 10. -18 Pa.

[0036] S4, Post-processing of the board material: The board surface was lightly acid-washed for 1 minute with a 2% dilute nitric acid solution to remove free MgO, followed by rinsing with deionized water. Subsequently, an insulating coating was applied to the cleaned substrate surface and cured at 200°C for 10 minutes.

[0037] The surface of the grain-oriented silicon steel was found to be free of scratches, and the roughness Ra deviation was ≤ ±0.08μm, indicating that the product was qualified.

[0038] Example 2 S1, Pre-treatment of the board material by a combination of degreasing and pickling: The degreasing temperature was controlled at 70℃ and the degreasing time was 4 minutes. The board was then pickled with a 6.5% dilute hydrochloric acid solution at a controlled temperature of 45℃ for 3 minutes. Subsequently, the board was rinsed with 12MPa high-pressure water and dried with hot air at 90℃, resulting in a surface roughness Ra of 0.4.

[0039] S2, Apply a release agent coating to the board: A high-purity magnesium oxide release agent with a MgO content of 96% was prepared and mixed with deionized water to form a suspension with a solid content of 35%. This suspension was then ultrasonically dispersed for 45 minutes. Next, the suspension was uniformly coated onto the surface of the board using a roller coating method, with the roller pressure controlled at 0.4 MPa and the coating speed at 12 m / min. Simultaneously, the thickness of the release agent layer on the board surface after drying was controlled at 12 μm, and the board was dried at 70℃ for 12 minutes.

[0040] S3, high-temperature annealing treatment of the board material: The sheet material was fed into a continuous annealing furnace for high-temperature secondary recrystallization annealing. The temperature was increased at a rate of 6°C / min and held at 820°C for 2.5 hours. The temperature was then increased to 1120°C and held for 12 hours, followed by a decrease to 580°C at a rate of 4°C / min before being removed from the furnace. The entire annealing process was carried out in a mixed protective atmosphere of N2 and H2, with the H2 volume percentage controlled at 25% and the oxygen potential in the furnace at 10. -17 Pa.

[0041] S4, Post-processing of the board material: The board surface was lightly acid-washed for 1 minute with a 2% dilute nitric acid solution to remove free MgO, followed by rinsing with deionized water. Subsequently, an insulating coating was applied to the cleaned substrate surface and cured at 200°C for 10 minutes.

[0042] The surface of the grain-oriented silicon steel was found to be free of scratches, and the roughness Ra deviation was ≤ ±0.09μm, indicating that the product was qualified.

[0043] Example 3 S1, Pre-treatment of the board material by a combination of degreasing and pickling: The degreasing temperature was controlled at 80℃ and the degreasing time was 5 minutes. The board was then pickled with an 8% dilute hydrochloric acid solution at a controlled temperature of 50℃ for 4 minutes. Subsequently, the board was rinsed with 15MPa high-pressure water and dried with hot air at 100℃, resulting in a surface roughness Ra of 0.5.

[0044] S2, Apply a release agent coating to the board: A high-purity magnesium oxide release agent with a MgO content of 97% was prepared and mixed with deionized water to form a suspension with a solid content of 40%. This suspension was then ultrasonically dispersed for 60 minutes. Next, the suspension was uniformly coated onto the surface of the board using a roller coating method, with the roller pressure controlled at 0.5 MPa and the coating speed at 15 m / min. Simultaneously, the thickness of the release agent layer on the board surface after drying was controlled at 15 μm, and the board was dried at 80℃ for 15 minutes.

[0045] S3, high-temperature annealing treatment of the board material: The sheet material was fed into a continuous annealing furnace for high-temperature secondary recrystallization annealing. The temperature was increased at a rate of 8°C / min and held at 850°C for 3 hours. The temperature was then increased to 1150°C and held for 15 hours, followed by a decrease to 580°C at a rate of 5°C / min before being removed from the furnace. Simultaneously, the entire annealing process was carried out in a mixed protective atmosphere of N2 and H2, with the H2 volume percentage controlled at 30% and the oxygen potential in the furnace at 10. -16 Pa.

[0046] S4, Post-processing of the board material: The board surface was lightly acid-washed for 2 minutes with a 3% dilute nitric acid solution to remove free MgO, followed by rinsing with deionized water. Subsequently, an insulating coating was applied to the cleaned substrate surface and cured at 250°C for 15 minutes.

[0047] The surface of the grain-oriented silicon steel was found to be free of scratches, and the roughness Ra deviation was ≤ ±0.10μm, indicating that the product was qualified.

[0048] Comparative Example 1 The surface pretreatment step S1 is omitted, and the remaining conditions are the same as in Example 2.

[0049] Testing revealed contamination on the board surface, severely uneven growth of the substrate, obvious surface scratches, and a roughness Ra deviation of ±0.5μm, making the product substandard.

[0050] Comparative Example 2 The dry film thickness of the release agent coating is 20 μm, with a thickness deviation of ±3 μm. The other conditions are the same as in Example 2.

[0051] Testing revealed uneven distribution of the release agent and the underlying layer, resulting in uneven insulation coating, clear scratch marks on the surface, and a roughness Ra deviation of ±0.3μm, indicating that the product was substandard.

[0052] like Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown in the product surface morphology diagrams and bottom cross-sectional diagrams of Examples 1-3 and Comparative Examples 1-2, it is clear that the oriented silicon steel produced using this control method has better product quality and the surface scratch problem is significantly improved.

[0053] As described above, this control method constructs a comprehensive synergistic optimization system encompassing "pretreatment-release agent-annealing-post-treatment," precisely controlling multiple stages from film-forming substrate, release agent distribution, high-temperature reaction to coating curing. This achieves synergistic and uniform forming of the substrate and glass film, overcoming the limitations of existing single-process optimization. Simultaneously, by optimizing the magnesium oxide release agent formulation and coating process, and through high-purity component control, ultrasonic dispersion, and precise roller coating parameter settings, the release agent coating thickness deviation is ensured to be ≤±1μm, providing a stable foundation for uniform substrate growth.

[0054] Furthermore, this control method precisely regulates the high-temperature annealing process parameters (heating rate, holding period, and atmospheric oxygen potential), simultaneously ensuring the quality of secondary recrystallization and the uniformity of the bottom layer formation, avoiding defects caused by differences in reaction rates. In addition, this process is compatible with existing production lines, requiring no additional core equipment; it can be achieved simply by adjusting parameters, thus balancing industrial feasibility and production economics.

[0055] Therefore, this embodiment can completely eliminate surface scratch marks on grain-oriented silicon steel from the root, resulting in a finished product surface with no visible scratch marks and a surface roughness Ra deviation of ≤±0.1μm at various locations, significantly improving surface quality. Simultaneously, this process requires no additional core equipment or complex post-processing steps, does not increase production costs or reduce production efficiency, is compatible with existing production lines for stable mass production, and significantly enhances product market competitiveness.

[0056] It should be noted that, unless otherwise stated, the technical or scientific terms used in this invention should have the ordinary meaning as understood by one of ordinary skill in the art.

[0057] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for controlling the consistency of surface scratch quality in grain-oriented silicon steel, characterized in that, Includes the following steps: S1, the board undergoes a combined pretreatment of degreasing and pickling; S2, apply a release agent coating to the board; S3, high-temperature annealing treatment of the board material; S4, post-processing of the board material; In S1, the combined degreasing and pickling pretreatment includes sequential degreasing, pickling, rinsing, and drying, wherein: Control the defatting temperature to 60-80℃ and the defatting time to 3-5 minutes; The board is pickled using a 5-8% dilute hydrochloric acid solution, and the pickling temperature is controlled at 40-50℃ and the pickling time is 2-4 minutes. The boards are rinsed with high-pressure water at 10-15MPa; Control the drying temperature to 80-100℃.

2. The control method according to claim 1, characterized in that, In S2, magnesium oxide release agent and deionized water are mixed to form a suspension with a solid content of 30-40%, and ultrasonic dispersion is performed for 30-60 minutes. Then, the suspension is uniformly coated on the surface of the board using a roller coating method, and the board is dried.

3. The control method according to claim 2, characterized in that, In S2, the mass percentage composition of the magnesium oxide separating agent is as follows: MgO ≥ 95%, SiO2 ≤ 2.0%, CaO ≤ 1.0%, with the balance being unavoidable impurities.

4. The control method according to claim 2, characterized in that, In S2, the coating roller pressure is controlled at 0.3-0.5MPa, the coating speed is controlled at 10-15m / min, the thickness of the release agent layer on the surface of the board after drying is controlled at 10-15μm, and the thickness deviation of the release agent layer at each position on the board surface is ≤±1μm.

5. The control method according to claim 2, characterized in that, In S2, the board is dried at 60-80℃ for 10-15 minutes to form a dense MgO coating layer.

6. The control method according to claim 1, characterized in that, In S3, the sheet material is sent into a continuous annealing furnace for high-temperature secondary recrystallization annealing. The sheet material is heated at a rate of 5-8℃ / min and held at 800-850℃ for 2-3 hours. The temperature is then increased to 1100-1150℃ and held for 10-15 hours. Finally, the temperature is reduced to below 600℃ at a rate of 3-5℃ / min before being removed from the furnace.

7. The control method according to claim 6, characterized in that, In S3, the plate annealing process is carried out in a mixed protective atmosphere of N2 and H2, with the volume percentage of H2 controlled at 20-30% and the oxygen potential in the furnace at 10. -18 -10 -16 Pa.

8. The control method according to claim 1, characterized in that, In S4, the board is lightly acid-washed and rinsed with deionized water. Then, an insulating coating is applied to the surface of the board, and the board is cured.

9. The control method according to claim 8, characterized in that, In S4, the board is lightly acid-washed for 1-2 minutes with a 2-3% dilute nitric acid solution to remove free MgO from the board surface.

10. The control method according to claim 8, characterized in that, In S4, the board is cured at 200-250°C for 10-15 minutes to form a uniform, insulating surface coating with tensile stress on the board surface.

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