An ultrathin non-oriented silicon steel and a preparation method thereof

Abstract

This application belongs to the field of electrical steel manufacturing technology, specifically relating to an ultra-thin non-oriented silicon steel and its preparation method. The preparation method includes: obtaining a silicon steel slab, and performing five cold rolling passes on the silicon steel slab to obtain ultra-thin non-oriented silicon steel. During the five cold rolling passes, there are no external heating sources or heat preservation equipment. The silicon content of the silicon steel slab is 4.0-4.5 wt%. The five cold rolling passes are sequentially divided into a first pass, a second pass, a third pass, a fourth pass, and a fifth pass. The initial rolling temperature of the first pass is room temperature, and the final rolling temperature of the first pass is 60-65℃. This application achieves a self-heating temperature by coordinating and matching the pass reduction rate, rolling speed, and tension, thereby achieving the target thickness and ensuring the plate shape.

Description

Technical Field

[0001] This application relates to the field of electrical steel manufacturing technology, specifically to an ultra-thin non-oriented silicon steel and its preparation method. Background Technology

[0002] With the rapid development of the low-altitude economy and new energy vehicles, the requirements for non-oriented silicon steel in new energy motors are becoming increasingly stringent. New energy motors operate at speeds far exceeding those of industrial motors, reaching up to 31,000 rpm. This necessitates that non-oriented silicon steel exhibit ultra-low iron loss and high magnetic flux density at frequencies ≥800Hz to ensure high-frequency magnetic performance. Furthermore, to overcome the centrifugal force of high-speed motor rotation, non-oriented silicon steel must possess high strength. Therefore, high-grade non-oriented silicon steel with a thickness ≤0.12mm has become the primary specification for new energy motors.

[0003] With increasing silicon content and extremely thin thicknesses, cold rolling of silicon steel has become a critical factor restricting the material's performance. Higher silicon content leads to greater cold brittleness, and the extremely thin thickness further complicates cold rolling. The thinner the electrical steel sheet, the higher the requirements for sheet shape, primarily due to thickness fluctuations and variations within the same sheet. For 0.5mm thick non-oriented silicon steel, variations within the same sheet have a relatively small impact, and normal rolling can meet the requirements. However, for 0.12mm thick and thinner non-oriented silicon steel, sheet shape significantly affects the lamination factor, thus impacting motor efficiency.

[0004] As silicon content increases, the difficulty of rolling increases dramatically. When the silicon content exceeds 4.0%, conventional rolling techniques include 6 or even 7 passes, aging, and preheating before rolling. However, more rolling passes increase the complexity of the control process, production costs, and efficiency, as well as roll wear. Furthermore, more rolling passes lead to more severe work hardening, making the later stages of rolling even more difficult. Some patents employ aging rolling, but this requires additional heating and insulation equipment, significantly increasing production costs and reducing efficiency.

[0005] Existing technology proposes a cold rolling preparation method for high-silicon non-oriented silicon steel. The entry temperature of the first stand in the cold rolling process is 200-250℃, which increases the heating equipment and the corresponding cost. Moreover, it takes several hours to heat the coiled silicon steel to 250℃, which reduces efficiency. The method uses continuous rolling technology, with the 3rd and 4th stands using alternating directional rolling at ±15°. This is intended to improve the texture and anisotropy, reduce the edge cracking rate, and finally roll to 0.25mm.

[0006] For cold rolling, the greater the thickness, the easier it is to control. As the thickness decreases, the sensitivity of silicon steel to stress increases exponentially. It is necessary to comprehensively consider the effects of reduction rate, temperature, speed, and tension; otherwise, it is easy to narrow the strip or even break it. Based on the above problems, there is an urgent need for a method to prepare ultra-thin non-oriented silicon steel (silicon content ≥4.0wt%, thickness ≤0.12mm) with fewer passes and no additional heating required. Summary of the Invention

[0007] To address the aforementioned technical problems, this application provides a method for preparing ultrathin non-oriented silicon steel, comprising: obtaining a silicon steel slab, and performing five cold rolling passes on the silicon steel slab to obtain ultrathin non-oriented silicon steel, wherein no external heating source or heat preservation equipment is used during the five cold rolling passes; the silicon content of the silicon steel slab is 4.0-4.5 wt%, and the five cold rolling passes are sequentially divided into a first pass, a second pass, a third pass, a fourth pass, and a fifth pass; wherein the initial rolling temperature of the first pass is room temperature, and the final rolling temperature of the first pass is 60-65℃.

[0008] As a preferred embodiment of the preparation method of ultra-thin non-oriented silicon steel described in this application, the silicon steel slab is hot-rolled, normalized, and pickled before the five-pass cold rolling, and the thickness of the silicon steel slab is 1.8-2.0 mm.

[0009] In a preferred embodiment of the method for preparing ultrathin non-oriented silicon steel as described in this application, the rolling speeds of the first, second, third, fourth, and fifth passes are 1200-1800 m / min, wherein the rolling speed of the first pass < the rolling speed of the second pass < the rolling speed of the third pass < the rolling speed of the fourth pass < the rolling speed of the fifth pass.

[0010] In a preferred embodiment of the method for preparing ultrathin non-oriented silicon steel as described in this application, the reduction rate of the first pass is 48%-50%, the reduction rate of the second pass is 44%-46%, the reduction rate of the third pass is 43%-45%, the reduction rate of the fourth pass is 40%-42%, and the reduction rate of the fifth pass is 40%-42%.

[0011] In a preferred embodiment of the method for preparing ultrathin non-oriented silicon steel as described in this application, the inlet tension of the first pass is 200-250 kN, and the outlet tension of the first pass is 100-120 kN; the inlet tension of the second pass is 180-220 kN, and the outlet tension of the second pass is 90-110 kN; the inlet tension of the third pass is 150-200 kN, and the outlet tension of the third pass is 80-100 kN; the inlet tension of the fourth pass is 120-150 kN, and the outlet tension of the fourth pass is 70-90 kN; the inlet tension of the fifth pass is 100-120 kN, and the outlet tension of the fifth pass is 60-80 kN.

[0012] In a preferred embodiment of the method for preparing ultrathin non-oriented silicon steel as described in this application, the initial rolling temperature of the second pass is 60-65℃, and the final rolling temperature of the second pass is 70-75℃; the initial rolling temperature of the third pass is 65-70℃, and the final rolling temperature of the third pass is 80-85℃; the initial rolling temperature of the fourth pass is 75-80℃, and the final rolling temperature of the fourth pass is 80-85℃; the initial rolling temperature of the fifth pass is 75-80℃, and the final rolling temperature of the fifth pass is 75-80℃.

[0013] As a preferred embodiment of the preparation method of ultrathin non-oriented silicon steel described in this application, the inlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is ≤1kN, and the outlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is ≤1kN.

[0014] This application also provides an ultrathin non-oriented silicon steel, which is prepared using the above-described method for preparing ultrathin non-oriented silicon steel.

[0015] As a preferred embodiment of the ultrathin non-oriented silicon steel described in this application, the thickness of the ultrathin non-oriented silicon steel is ≤0.12mm.

[0016] As a preferred embodiment of the ultra-thin non-oriented silicon steel described in this application, the thickness dimensional tolerance of the ultra-thin non-oriented silicon steel is within ±0.002mm, the same-plate difference of the ultra-thin non-oriented silicon steel is ≤3μm, and the lamination factor of the ultra-thin non-oriented silicon steel is ≥99%.

[0017] The beneficial effects of this application are as follows: This application proposes a method for preparing ultrathin non-oriented silicon steel. Under high silicon content (4.0-4.5wt%), this application uses a non-preheating and non-aging technology to roll ultrathin non-oriented electrical steel in 5 passes, with a finished product thickness ≤0.12mm. The dimensional tolerance of the thickness of the finished silicon steel is within ±0.002mm, the difference between the same plate is ≤3μm, and the stacking factor is ≥99%. By coordinating and matching the pass reduction rate, rolling speed, and tension, a self-heating temperature is obtained to achieve the target thickness and ensure the plate shape.

[0018] This application employs a single-pass cold rolling technology, eliminating the need for intermediate aging treatment or preheating before rolling. Through five passes with varying reduction rates, and by configuring appropriate tension and rolling speed, ideal thickness and strip shape are achieved. This application uses a five-pass rolling process. A higher reduction rate per pass results in excessively high silicon content, leading to excessive mill bounce and excessive thickness fluctuations. Conversely, a lower reduction rate, even with five passes, cannot achieve an extremely thin strip, necessitating additional passes and increasing costs. Furthermore, a low reduction rate results in insufficient deformation heat, leading to inadequate rolling temperature. Tension, reduction rate, strip thickness, and speed must be strictly matched. Excessive tension can easily lead to narrowing or even breakage; insufficient tension results in poor strip flatness under high-speed rolling. Additionally, the tension difference between the silicon steel slab at the mill inlet and outlet must be controlled to ≤1kN. Otherwise, under high tension, high reduction rate, and high-speed rolling, uneven stress on both sides can easily cause stress concentration and strip breakage. The rolling speed, temperature, reduction rate, and tension must be matched. A low rolling speed results in less frictional heat and faster heat dissipation, leading to insufficient temperature. Conversely, an excessively high rolling speed leads to instability, poor strip shape, and even strip breakage. From the first to the fifth pass, the silicon steel thickness decreases, and heat dissipation accelerates. To maintain the strip temperature, increasingly higher rolling speeds are required to minimize heat loss. Therefore, for high-silicon steel, a strict match between the pass reduction rate, rolling speed, and tension is essential to ensure proper rolling temperature and strip shape. This application achieves pass rolling temperature control between 60-85℃ through coordinated control of the pass reduction rate, speed, and tension. The processing is matched to the motor's operating environment, and smooth rolling is achieved through technical control, thus eliminating the need for aging processes.

[0019] The technological innovation of this application lies in eliminating temperature requirements for cold-rolled raw materials, allowing rolling to begin at room temperature. It utilizes the rolling heat generated by the high reduction rate in each pass, matched with high-speed rolling, to achieve self-heating of the silicon steel, raising it from room temperature to a maximum of 80-85℃, thus reducing the material's brittleness. Therefore, ensuring a high reduction rate in each pass is crucial to generating sufficient rolling heat. Insufficient reduction rate results in insufficient rolling heat and difficulty in heating; excessive reduction rate leads to large mill bounce, significant thickness fluctuations, and increased risk of breakage. Simultaneously, matching each pass with high-speed rolling ensures that slow speed leads to rapid heat dissipation and minimal temperature rise; excessive speed results in unstable rolling, leading to steel accumulation and strip breakage. Compared to traditional silicon steel preheating technology, this overcomes the limitations of raw material temperature, allowing for greater production flexibility; compared to aging rolling technology, it saves on heating equipment and improves production speed; compared to multi-pass technology with low reduction rates, it reduces mill investment, lowers costs, and significantly improves production efficiency. This technology allows for the production of ultra-thin non-oriented silicon steel while ensuring that the dimensional tolerances of the silicon steel thickness and the differences within the same plate are controlled at the limit level, achieving a lamination factor of ≥99%. Detailed Implementation

[0020] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] This application provides a method for preparing ultrathin non-oriented silicon steel, including: A silicon steel slab is obtained, and the slab is subjected to five cold rolling passes to obtain ultra-thin non-oriented silicon steel. During the five cold rolling passes, no external heating source or insulation equipment is used. The silicon content of the silicon steel slab is 4.0-4.5 wt%. The five cold rolling passes are sequentially divided into the first pass, the second pass, the third pass, the fourth pass, and the fifth pass. The initial rolling temperature of the first pass is room temperature, and the final rolling temperature of the first pass is 60-65℃. The silicon steel slab is hot-rolled, normalized, and pickled before undergoing the five cold rolling passes. The thickness of the silicon steel slab is 1.8-2.0 mm. The rolling speed of the first pass, the second pass, the third pass, the fourth pass, and the fifth pass is 1200-1800 m / min, and the rolling speed of the first pass is < the rolling speed of the second pass < the rolling speed of the third pass < the rolling speed of the fourth pass < the rolling speed of the fifth pass. The reduction rate of the first pass is 48%-50%, the reduction rate of the second pass is 44%-46%, the reduction rate of the third pass is 43%-45%, the reduction rate of the fourth pass is 40%-42%, and the reduction rate of the fifth pass is 40%-42%. The inlet tension of the first pass is 200-250 kN, and the outlet tension of the first pass is 100-120 kN; the inlet tension of the second pass is 180-220 kN, and the outlet tension of the second pass is 90-110 kN; the inlet tension of the third pass is 150-200 kN, and the outlet tension of the third pass is 80-100 kN; the inlet tension of the fourth pass is 120-150 kN, and the outlet tension of the fourth pass is 70-90 kN; the inlet tension of the fifth pass is 100-120 kN, and the outlet tension of the fifth pass is 60-80 kN. The initial rolling temperature of the second pass is 60-65℃, and the final rolling temperature of the second pass is 70-75℃; the initial rolling temperature of the third pass is 65-70℃, and the final rolling temperature of the third pass is 80-85℃; the initial rolling temperature of the fourth pass is 75-80℃, and the final rolling temperature of the fourth pass is 80-85℃; the initial rolling temperature of the fifth pass is 75-80℃, and the final rolling temperature of the fifth pass is 75-80℃. The inlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is ≤1kN, and the outlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is ≤1kN.

[0022] This application also provides an ultrathin non-oriented silicon steel, which is prepared by the above-described method for preparing ultrathin non-oriented silicon steel; The thickness of the ultra-thin non-oriented silicon steel is ≤0.12mm; the dimensional tolerance of the thickness of the ultra-thin non-oriented silicon steel is within ±0.002mm; the same-plate difference of the ultra-thin non-oriented silicon steel is ≤3μm; and the lamination factor of the ultra-thin non-oriented silicon steel is ≥99%.

[0023] The technical solution of this application will be further described below with reference to specific embodiments.

[0024] Example 1 This application provides a method for preparing ultrathin non-oriented silicon steel, including: A silicon steel slab is obtained and then subjected to five cold rolling passes to obtain ultra-thin non-oriented silicon steel. During the five cold rolling passes, no external heating source or insulation equipment is used. The composition of the silicon steel slab is: Si: 4.0 wt%, Al: 1.01 wt%, Mn: 1.00 wt%, C + S + O + N < 60 ppm, with the remainder being Fe and unavoidable impurities. The five cold rolling passes are sequentially divided into the first, second, third, fourth, and fifth passes. The initial rolling temperature for the first pass is room temperature, and the final rolling temperature for the first pass is 65℃. Before undergoing five cold rolling passes, the silicon steel slab is hot rolled, normalized, and pickled. The thickness of the silicon steel slab is 2.0 mm. The rolling speed for the first pass is 1200 m / min, the rolling speed for the second pass is 1300 m / min, the rolling speed for the third pass is 1400 m / min, the rolling speed for the fourth pass is 1500 m / min, and the rolling speed for the fifth pass is 1600 m / min. The first pass had a reduction rate of 48%, the second pass had a reduction rate of 44%, the third pass had a reduction rate of 43%, the fourth pass had a reduction rate of 40%, and the fifth pass had a reduction rate of 40%. The inlet tension for the first pass is 250 kN, and the outlet tension is 120 kN; the inlet tension for the second pass is 220 kN, and the outlet tension is 110 kN; the inlet tension for the third pass is 200 kN, and the outlet tension is 100 kN; the inlet tension for the fourth pass is 150 kN, and the outlet tension is 90 kN; the inlet tension for the fifth pass is 120 kN, and the outlet tension is 80 kN. The rolling temperature for the second pass is 65℃ and the rolling temperature for the final pass is 75℃; the rolling temperature for the third pass is 70℃ and the rolling temperature for the final pass is 85℃; the rolling temperature for the fourth pass is 80℃ and the rolling temperature for the final pass is 85℃; the rolling temperature for the fifth pass is 80℃ and the rolling temperature for the final pass is 80℃. The inlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is 0.5 kN, and the outlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is 0.3 kN.

[0025] The prepared ultrathin non-oriented silicon steel was tested, and the results showed that the thickness of the ultrathin non-oriented silicon steel was 0.12 mm; the dimensional tolerance of the thickness was ±0.0015 mm, the difference between the same plate was 3 μm, and the stacking factor was 99%.

[0026] Example 2 This application provides a method for preparing ultrathin non-oriented silicon steel, including: A silicon steel slab is obtained and then subjected to five cold rolling passes to obtain ultra-thin non-oriented silicon steel. During the five-pass cold rolling process, no external heating source or insulation equipment is used. The composition of the silicon steel slab is: Si: 4.5wt%, Al: 1.01wt%, Mn: 1.01wt%, C+S+O+N < 60ppm, with the remainder being Fe and unavoidable impurities. The five cold rolling passes are sequentially divided into the first pass, second pass, third pass, fourth pass, and fifth pass. The initial rolling temperature for the first pass is room temperature, and the final rolling temperature for the first pass is 60℃. Before undergoing five cold rolling passes, the silicon steel slab is hot rolled, normalized, and pickled. The thickness of the silicon steel slab is 1.8 mm. The rolling speed for the first pass is 1200 m / min, the rolling speed for the second pass is 1300 m / min, the rolling speed for the third pass is 1500 m / min, the rolling speed for the fourth pass is 1700 m / min, and the rolling speed for the fifth pass is 1800 m / min. The first pass had a reduction rate of 50%, the second pass had a reduction rate of 46%, the third pass had a reduction rate of 45%, the fourth pass had a reduction rate of 42%, and the fifth pass had a reduction rate of 42%. The inlet tension for the first pass is 200 kN, and the outlet tension is 100 kN; the inlet tension for the second pass is 180 kN, and the outlet tension is 90 kN; the inlet tension for the third pass is 150 kN, and the outlet tension is 80 kN; the inlet tension for the fourth pass is 120 kN, and the outlet tension is 70 kN; the inlet tension for the fifth pass is 100 kN, and the outlet tension is 60 kN. The second pass has an initial rolling temperature of 60℃ and a final rolling temperature of 70℃; the third pass has an initial rolling temperature of 65℃ and a final rolling temperature of 80℃; the fourth pass has an initial rolling temperature of 75℃ and a final rolling temperature of 80℃; and the fifth pass has an initial rolling temperature of 75℃ and a final rolling temperature of 75℃. The inlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is 0.4 kN, and the outlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is 0.25 kN.

[0027] The prepared ultrathin non-oriented silicon steel was tested, and the results showed that the thickness of the ultrathin non-oriented silicon steel was 0.09 mm; the dimensional tolerance of the thickness was ±0.0012 mm, the difference between the same plate was 2.8 μm, and the stacking factor was 99.5%.

[0028] Comparative Example 1 The difference between this comparative example and Example 1 is that the reduction rate in the first pass was 55%; as a result, strip breakage occurred during the rolling process.

[0029] Comparative Example 2 The difference between this comparative example and Example 1 is that the inlet tension of the first pass is 300kN and the outlet tension is 150kN; as a result, strip breakage occurred during the rolling process.

[0030] Comparative Example 3 The difference between this comparative example and Example 1 is that the inlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is 1.3 kN, and the outlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is 1.1 kN. The prepared ultrathin non-oriented silicon steel was tested, and the results showed that the thickness of the ultrathin non-oriented silicon steel was 0.13 mm; the dimensional tolerance of the thickness was ±0.0065 mm, the difference between the same plate was 8 μm, the stacking factor was 95.8%, and the plate shape of the ultrathin non-oriented silicon steel was poor.

[0031] Comparative Example 4 The difference between this comparative example and Example 1 is that the silicon content of the silicon steel slab is 3.5 wt%; The prepared ultrathin non-oriented silicon steel was tested, and the results showed that the thickness of the ultrathin non-oriented silicon steel was 0.12 mm; the dimensional tolerance of the thickness was ±0.01 mm, the difference between the same plate was 7 μm, the stacking factor was 96%, and the plate shape of the ultrathin non-oriented silicon steel was poor.

[0032] Comparative Example 5 The difference between this comparative example and Example 1 is that the silicon content of the silicon steel slab is 5.0 wt%; The prepared ultrathin non-oriented silicon steel was tested, and the results showed that the thickness of the ultrathin non-oriented silicon steel was 0.15 mm; the dimensional tolerance of the thickness was ±0.012 mm, the difference between the same plate was 10 μm, the stacking factor was 93%, and the plate shape of the ultrathin non-oriented silicon steel was poor.

[0033] Comparative Example 6 The difference between this comparative example and Example 1 is that the rolling speed for the first, second, third, fourth, and fifth passes is 800 m / min; as a result, strip breakage occurred during the rolling process.

[0034] Comparative Example 7 The difference between this comparative example and Example 1 is that the reduction rate in the first pass is 35%; as a result, strip breakage occurred during the rolling process.

[0035] Comparative Example 8 The difference between this comparative example and Example 1 is that the rolling speed for the first, second, third, fourth, and fifth passes is 2000 m / min. The prepared ultrathin non-oriented silicon steel was tested, and the results showed that the thickness of the ultrathin non-oriented silicon steel was 0.11 mm; the dimensional tolerance of the thickness was ±0.008 mm, the difference between the same plate was 9 μm, the stacking factor was 95.5%, and surface defects such as wrinkles existed.

[0036] Comparative Example 9 The difference between this comparative example and Example 1 is that the rolling speeds of the first, second, third, fourth, and fifth passes are equal, all being 1500 m / min. The prepared ultrathin non-oriented silicon steel was tested, and the results showed that the thickness of the ultrathin non-oriented silicon steel was 0.10 mm; the dimensional tolerance of the thickness was ±0.005 mm, the difference between the same plate was 7 μm, the lamination factor was 97%, and edge crack defects existed.

[0037] The above embodiments and comparative examples show that: Example 1, combined with Comparative Example 1, indicates that an excessive reduction rate per pass leads to an excessively thin silicon steel slab, exceeding the material strength and causing it to break directly during rolling; Example 1, combined with Comparative Example 2, indicates that excessive tension, exceeding the material strength, similarly narrows or even breaks the material; Example 1, combined with Comparative Example 3, indicates that excessive tension difference on both sides leads to uneven stress on the material, significantly worsening the slab shape and reducing the same-slab difference and stacking coefficient; Example 1, combined with Comparative Example 4, indicates that this method is suitable for silicon content of 4-4.5 wt%. Within this composition range, the hardness, strength, and reduction rate of the material are matched, and the mill bounce is controlled to obtain a suitable thickness and tolerance. If the content is less than the range of this application, the hardness and strength are insufficient, and with the same reduction rate, the mill bounce is small, and the thickness is uncontrollable; Example 1, combined with Comparative Example 5, indicates that if the content is greater than the range of this application... The following are examples of problems: High hardness and strength lead to large mill bounce, uncontrolled thickness, and low rolling efficiency, resulting in excessively thick final products. Example 1, in conjunction with Comparative Example 6, shows that excessively low rolling speeds result in long rolling times, excessive heat dissipation from the silicon steel slab, and failure to reach the temperature range described in this application, leading to high material brittleness and direct strip breakage. Example 1, in conjunction with Comparative Example 7, shows that insufficient reduction ratio prevents the rolling heat from raising the silicon steel slab to the temperature range described in this application, resulting in high material brittleness and direct strip breakage. Example 1, in conjunction with Comparative Example 8, shows that excessively high rolling speeds, mismatched with tension, lead to unstable rolling, resulting in large dimensional tolerances in the thickness of the silicon steel product, wrinkling defects, and a reduced stacking coefficient. Example 1, in conjunction with Comparative Example 9, shows that if the rolling speed does not gradually increase with each pass, it leads to increased rolling time in subsequent passes, excessive heat dissipation, insufficient temperature rise, increased brittleness, and edge cracking.

[0038] The technological innovation of this application lies in eliminating temperature requirements for cold-rolled raw materials, allowing rolling to begin at room temperature. It utilizes the rolling heat generated by the high reduction rate in each pass, matched with high-speed rolling, to achieve self-heating of the silicon steel, raising it from room temperature to a maximum of 80-85℃, thus reducing the material's brittleness. Therefore, ensuring a high reduction rate in each pass is crucial to generating sufficient rolling heat. Insufficient reduction rate results in insufficient rolling heat and difficulty in heating; excessive reduction rate leads to large mill bounce, significant thickness fluctuations, and increased risk of breakage. Simultaneously, matching each pass with high-speed rolling ensures that slow speed leads to rapid heat dissipation and minimal temperature rise; excessive speed results in unstable rolling, leading to steel accumulation and strip breakage. Compared to traditional silicon steel preheating technology, this overcomes the limitations of raw material temperature, allowing for greater production flexibility; compared to aging rolling technology, it saves on heating equipment and improves production speed; compared to multi-pass technology with low reduction rates, it reduces mill investment, lowers costs, and significantly improves production efficiency. This technology allows for the production of ultra-thin non-oriented silicon steel while ensuring that the dimensional tolerances of the silicon steel thickness and the differences within the same plate are controlled at the limit level, achieving a lamination factor of ≥99%.

[0039] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for producing an ultrathin non-oriented silicon steel, characterized by, include: A silicon steel slab is obtained, and the slab is subjected to five cold rolling passes to obtain ultra-thin non-oriented silicon steel. During the five cold rolling passes, no external heating source or insulation equipment is used. The silicon content of the silicon steel slab is 4.0-4.5 wt%. The five cold rolling passes are sequentially divided into the first pass, the second pass, the third pass, the fourth pass, and the fifth pass. The initial rolling temperature of the first pass is room temperature, and the final rolling temperature of the first pass is 60-65℃. The rolling speed of the first pass, the second pass, the third pass, the fourth pass, and the fifth pass is 1200-1800 m / min, and the rolling speed of the first pass is < the rolling speed of the second pass < the rolling speed of the third pass < the rolling speed of the fourth pass < the rolling speed of the fifth pass. The initial rolling temperature of the second pass is 60-65℃, and the final rolling temperature of the second pass is 70-75℃; the initial rolling temperature of the third pass is 65-70℃, and the final rolling temperature of the third pass is 80-85℃; the initial rolling temperature of the fourth pass is 75-80℃, and the final rolling temperature of the fourth pass is 80-85℃; the initial rolling temperature of the fifth pass is 75-80℃, and the final rolling temperature of the fifth pass is 75-80℃.

2. The method of producing an ultrathin non-oriented silicon steel according to claim 1, characterized by, Before undergoing the five cold rolling passes, the silicon steel slab is hot rolled, normalized, and pickled. The thickness of the silicon steel slab is 1.8-2.0 mm.

3. The method of producing an ultrathin non-oriented silicon steel according to claim 1, characterized in that, The reduction rate of the first pass is 48%-50%, the reduction rate of the second pass is 44%-46%, the reduction rate of the third pass is 43%-45%, the reduction rate of the fourth pass is 40%-42%, and the reduction rate of the fifth pass is 40%-42%.

4. The method of claim 1, wherein the thickness of the ultra-thin non-oriented silicon steel is 0.8 mm or less. The inlet tension of the first pass is 200-250 kN, and the outlet tension of the first pass is 100-120 kN; the inlet tension of the second pass is 180-220 kN, and the outlet tension of the second pass is 90-110 kN; the inlet tension of the third pass is 150-200 kN, and the outlet tension of the third pass is 80-100 kN; the inlet tension of the fourth pass is 120-150 kN, and the outlet tension of the fourth pass is 70-90 kN; the inlet tension of the fifth pass is 100-120 kN, and the outlet tension of the fifth pass is 60-80 kN.

5. The method of claim 1, wherein the thickness of the ultra-thin non-oriented silicon steel is 0.8 mm or less. The inlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is ≤1kN, and the outlet tension difference between the two sides of the silicon steel slab in the first, second, third, fourth, and fifth passes is ≤1kN.

6. An ultra-thin non-oriented silicon steel, characterized in that, It is prepared by the preparation method of any one of claims 1-5 for ultrathin non-oriented silicon steel.

7. The ultra-thin non-oriented silicon steel according to claim 6, characterized in that, The thickness of the ultra-thin non-oriented silicon steel is ≤0.12mm.

8. The ultra-thin non-oriented silicon steel according to claim 6, characterized in that, The thickness tolerance of the ultra-thin non-oriented silicon steel is within ±0.002mm, the same-plate difference of the ultra-thin non-oriented silicon steel is ≤3μm, and the lamination factor of the ultra-thin non-oriented silicon steel is ≥99%.