Thin-gauge high-silicon electrical steel strip and preparation method thereof

Abstract

The invention relates to a thin-gauge high-silicon electrical steel strip and a preparation method thereof. The preparation method comprises the following steps: smelting and casting raw materials to obtain a casting blank; carrying out hot rolling on the casting blank to obtain a hot-rolled plate, and then carrying out normalizing treatment; the normalized hot-rolled plate is subjected to acid pickling and then subjected to multi-pass cold rolling, and the cold rolling reduction rate is gt; 80%, obtaining a cold-rolled strip; the cold-rolled strip is subjected to decarburization annealing and secondary recrystallization annealing, and an oriented silicon steel base material is obtained; the oriented silicon steel base material is put into a siliconizing furnace, nanoscale silicon oxide powder is sprayed into a furnace cavity, and siliconizing treatment is carried out under the conditions that the temperature is 800-1200 DEG C and the pressure of the furnace cavity is 0.1-0.2 MPa; and carrying out homogenization treatment on the siliconized base material at 200-400 DEG C in a protective atmosphere to obtain the thin-gauge high-silicon electrical steel strip.

Description

Technical Field

[0001] This invention belongs to the technical field of thin-gauge high-silicon electrical steel strip, specifically relating to a thin-gauge high-silicon electrical steel strip and its preparation method. Background Technology

[0002] Electrical steel strip, as a core soft magnetic material for power equipment, directly determines the energy efficiency and operational stability of key equipment such as transformers and motors due to its magnetic properties and iron loss characteristics, playing an irreplaceable role in energy conversion and transmission. High-silicon electrical steel strip, with its excellent magnetic permeability, extremely low iron loss, and good corrosion resistance, has become the preferred material for high-end power equipment such as ultra-high voltage transformers, high-frequency motors, and energy storage converters, leading to continuously rising market demand. Furthermore, thinner specifications further reduce eddy current losses under high-frequency operating conditions, perfectly aligning with the high-frequency and miniaturization trends in fields such as medium- and high-frequency transformers, new energy vehicle drive motors, and aerospace power supplies.

[0003] The current preparation of high-silicon electrical steel strip faces a core technological bottleneck that is difficult to overcome: the solid solution strengthening effect of silicon in the iron matrix causes a sharp decrease in the plasticity of the steel. The higher the silicon content, the more brittle the material becomes, and the difficulty of cold rolling increases exponentially. When using traditional cold rolling processes to prepare thin-gauge products, the steel strip is prone to defects such as edge cracks and strip breakage during the rolling process, requiring multiple intermediate annealings to restore plasticity. This not only leads to longer production cycles and reduced efficiency but also significantly increases energy consumption and production costs. If a casting-rolling process is used instead, although it can refine the grains and improve some mechanical properties through rapid solidification, an uneven oxide layer is easily formed on the surface of the thin strip, which can easily lead to localized over-corrosion during subsequent pickling, causing excessive thickness fluctuations.

[0004] In existing technologies, the production of thin-gauge high-silicon steel strips often employs a compromise solution of "reducing silicon content while preserving shape," controlling the silicon content below 4.0 wt%. This sacrifices magnetic properties to ensure formability, failing to meet the requirements of high-end equipment. While some companies have attempted to produce high-silicon products, they rely on imported high-precision rolling equipment, with each production line requiring an investment exceeding 100 million yuan, creating an extremely high barrier to entry. Furthermore, finished steel strips produced using existing processes suffer from uneven magnetic properties and large fluctuations in iron loss values, making it difficult to meet the stringent material stability requirements of high-end equipment.

[0005] Therefore, it is urgent to develop a low-cost preparation technology that takes into account high silicon content, thin-gauge characteristics, and molding stability, which is the key to promoting the upgrading of the electrical steel strip industry. Summary of the Invention

[0006] To address the problems of high brittleness, difficulty in cold rolling, and uneven magnetic properties caused by the high silicon content in existing high-silicon electrical steels, this invention provides a method for preparing high-silicon electrical steel strips, comprising the following steps: The raw materials are smelted and cast to obtain a billet; The billet is hot-rolled to obtain a hot-rolled plate, which is then normalized. The normalized hot-rolled plate is pickled and then subjected to multiple cold rolling passes with a cold rolling reduction rate of >80% to obtain cold-rolled strip. The cold-rolled strip is subjected to decarburization annealing and secondary recrystallization annealing to obtain oriented silicon steel base material; The oriented silicon steel base material is placed in a silicon diffusion furnace, and nano-sized silicon oxide powder is sprayed into the furnace cavity. Silicon diffusion treatment is carried out under the conditions of 800℃~1200℃ and furnace cavity pressure of 0.1~0.2MPa. The silicon-infiltrated base material is homogenized at 200-400°C in a protective atmosphere to obtain the thin-gauge high-silicon electrical steel strip.

[0007] Preferably, the process parameters of the silicon infiltration treatment satisfy one or more of the following: The mass ratio of the silicon oxide powder to the oriented silicon steel base material is 1:10; The powder injection pressure is 0.3~0.6MPa; The protective gas is high-purity argon, and the dew point is controlled at -20℃ to -10℃; The heat preservation time is 8h~20h; The base material winding density is 4~6 g / cm³. 3 .

[0008] Preferably, the particle diameter of the silicon oxide powder is 1~20 nm.

[0009] Preferably, the silicon oxide powder is one or more of quartz, crystal, silica, diatomaceous earth, and silica gel.

[0010] Preferably, the furnace cavity pressure for homogenization treatment is 0.3~0.6MPa, and the holding time is 2h~5h.

[0011] Preferably, the smelting and casting specifically includes: using a converter or electric furnace to perform preliminary smelting of the metal raw materials, controlling the carbon content of the molten steel after preliminary smelting to be 0.01%~0.07%, and tapping the steel at a temperature of 1550℃~1700℃. Subsequently, the molten steel is transferred to a refining furnace for purification, with a furnace vacuum degree <100Pa and a constant temperature for 10~30min. After refining, the carbon content should be <60ppm. The refined molten steel is then injected into a continuous casting machine to form a billet. The casting temperature of the molten steel should be maintained at 10~50℃ for superheating, and the billet thickness should be 50~300mm.

[0012] Preferably, the hot rolling specifically includes: heating the billet at a uniform temperature of 1100℃~1400℃ for 3~10 hours; rough rolling at 1000~1300℃, followed by finish rolling at 900~1000℃, with a final rolling temperature of 800~1000℃, to obtain a hot-rolled plate with a thickness of 2~3mm, and a coiling temperature of 400~650℃.

[0013] The normalization process includes: placing the sample in a normalization furnace for normalization at a temperature of 1100°C for 3-10 minutes, followed by air cooling to room temperature after normalization.

[0014] Preferably, the pickling uses a hydrochloric acid solution with a concentration of 10% to 30% and a temperature of 50 to 90°C; the cold rolling process consists of 3 to 7 passes, and the rolling tensile stress is 80 to 200 MPa.

[0015] Preferably, the decarburization annealing temperature is 700℃~850℃, the holding time is 1~10min, and the protective gas is a mixture of hydrogen and nitrogen. In the hydrogen-nitrogen mixture, the hydrogen component is 30% to 60%, and water vapor is added to control the dew point to be +40℃ to +60℃.

[0016] Preferably, the annealing temperature of the secondary recrystallization annealing is 1100℃~1250℃, the protective gas is high-purity hydrogen, the furnace pressure is 0.01MPa~0.10MPa, and the holding time is 4h~20h.

[0017] Preferably, after the secondary recrystallization annealing is completed, the furnace is cooled to 800°C at a rate of ≤40°C / h, and then naturally cooled to room temperature.

[0018] Preferably, the raw materials comprise, by mass percentage: Si: 3.5%~6.5%, C: ≤0.005%, P: ≤0.003%, S: ≤0.003%, Al: 0.01%~0.05%, Mn: 0.03%~0.15%, Cu: 0.01%~0.1%, B: 0.002%~0.007%, with the remainder being Fe and unavoidable impurity elements.

[0019] The present invention also provides a thin-gauge high-silicon electrical steel strip prepared by the aforementioned preparation method. Preferably, the thickness of the thin-gauge high-silicon electrical steel strip is 0.03~0.30mm.

[0020] Preferably, the magnetic induction intensity B800 of the thin-gauge high-silicon electrical steel strip is ≥1.33T; and / or The hysteresis coefficient of the thin-gauge high-silicon electrical steel strip is ≤0.5×10. -6 .

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The proposed method for preparing thin-gauge high-silicon electrical steel strip employs a high-pressure solid-state powder spraying silicon infiltration followed by low-temperature homogenization, effectively avoiding the environmental pollution and equipment corrosion problems associated with traditional CVD methods for preparing high-silicon electrical steel strip. Furthermore, this technical solution features a simple process, short flow, and easily controllable silicon infiltration. The diffusion of nano-sized silicon oxide powder into the silicon steel matrix under high pressure and high temperature conditions is more uniform, reducing the surface energy caused by Si atom diffusion and its impact on the Goss texture of the matrix. This contributes to obtaining high-silicon electrical steel with high magnetic induction and low hysteresis coefficient.

[0022] The thin-gauge high-silicon electrical steel strip of this invention incorporates trace amounts of boron, aluminum, and copper, which simultaneously improve the brittleness and magnetic properties of high-silicon electrical steel. The core benefit of boron lies in its strong tendency for grain boundary segregation, which effectively strengthens grain boundaries and significantly improves the hot brittleness caused by grain boundary weakening during hot working of high-silicon steel. It also refines the grains during final annealing. The addition of aluminum mainly plays a role in solid solution strengthening and purification. It not only increases resistivity to reduce eddy current losses but also combines with impurity elements such as oxygen and nitrogen to form compounds, purifying the matrix and helping to obtain a more perfect recrystallization texture, thereby improving magnetic induction intensity. The addition of copper mainly promotes the precipitation of copper-rich phases at the nanoscale, inhibits the growth of primary recrystallized grains, and dissolves during high-temperature annealing, creating conditions for the rapid growth of subsequent grains. This is conducive to obtaining coarse, uniform Goss texture grains, achieving the best balance between iron loss and magnetic induction. Attached Figure Description

[0023] Figure 1 The image shows the microstructure and texture morphology of the thin-gauge high-silicon electrical steel strip of Embodiment 1 of the present invention. Figure 2 The image shows the microstructure and texture of the thin-gauge high-silicon electrical steel strip in Embodiment 2 of the present invention. Figure 3 This is a microstructure and texture morphology diagram of the thin-gauge high-silicon electrical steel strip of Embodiment 3 of the present invention. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other instances that are improved or modified by those skilled in the art are within the scope of protection of the present invention. It should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the methods used in the embodiments are conventional methods.

[0025] Example 1 This embodiment provides a thin-gauge high-silicon electrical steel strip, the preparation method of which includes the following steps: (1) Smelting and casting: The metal raw materials are initially smelted using a converter or electric furnace. The alloy composition by mass percentage is: Si: 3.5%, C: 0.005%, P: 0.003%, S: 0.003%, Al: 0.01%, Mn: 0.03%, Cu: 0.01%, B: 0.002%, with the remainder being Fe and unavoidable impurity elements. After initial smelting, the carbon content of the molten steel is controlled at 0.01%, and the tapping temperature is 1550℃. Subsequently, the molten steel is transferred to a refining furnace for purification. The furnace cavity vacuum is 90Pa, and the temperature is constant for 10min. After refining, the carbon content is 50ppm. The refined molten steel is injected into a continuous casting machine to form a billet. The casting temperature of the molten steel should be kept at 10℃ for overheating, and the billet thickness is 50mm. (2) Hot rolling and normalizing: The billet is uniformly heated at 1100℃ and held at that temperature for 3 hours. After the holding temperature is reached, it is subjected to multi-pass reversible high-reduction rough rolling at 1000℃, followed by finish rolling at 900℃. The final rolling temperature is about 800℃, the thickness of the hot-rolled plate is 2mm, and the coiling temperature is 400℃. The hot-rolled coil is placed in a normalizing furnace for normalizing treatment at 1100℃ for 3 minutes. After normalizing, it is air-cooled to room temperature. (3) Pickling and cold rolling: Hydrochloric acid solution is used to remove iron oxide scale from the surface of hot-rolled plate. The concentration of hydrochloric acid solution is 10% and the temperature is 50℃. After pickling, multiple passes of cold rolling are used to reduce the thickness to the final thickness. The cold rolling reduction rate is >80%, the rolling passes are 3, and the rolling tensile stress is 80MPa. (4) Decarburization and secondary recrystallization annealing: The cold-rolled strip is placed in a continuous annealing furnace at an annealing temperature of 700℃. The protective gas atmosphere is a mixture of hydrogen and nitrogen with a hydrogen component of 30%. Water vapor is added, and the dew point is strictly controlled at +40℃ to +60℃. The holding time is 1 min. After the decarburization annealing, the steel coil is subjected to long-term secondary recrystallization annealing in the annealing furnace at an annealing temperature of 1100℃. The protective gas atmosphere is high-purity hydrogen. The pressure inside the annealing furnace is 0.01 MPa. The holding time is 4 h. After the annealing, the steel coil is cooled to 800℃ in the furnace at a cooling rate of ≤40℃ / h. Then it is naturally cooled to room temperature, and the grain-oriented silicon steel base material is collected. (5) High-pressure solid powder spraying for silicon infiltration: The stains and oxide layer on the surface of the grain-oriented silicon steel base material are removed by water washing brush rollers and light acid washing. The cleaned grain-oriented silicon steel base material coil is placed in the silicon infiltration furnace. The winding density of the base material is 4 g / cm³. 3 Quartz powder with a diameter of 1 nm was sprayed into the silicon infiltration furnace cavity at a spraying pressure of 0.3 MPa. The mass ratio of silicon oxide powder to silicon steel base material was 1:10. The silicon infiltration temperature was 800℃, the holding time was 8 hours, the protective gas atmosphere was high-purity argon with added water vapor, the dew point was strictly controlled at -20℃ to -10℃, and the furnace cavity pressure was 0.1 MPa. (6) Low-temperature homogenization: After cleaning the surface of the silicon-infiltrated base material by ultrasonic vibration and water washing roller, it is placed in a bell furnace for homogenization treatment. The annealing temperature is 200℃, the holding time is 2h, the protective atmosphere is high-purity argon, and the furnace pressure is 0.3MPa to obtain the thin-gauge high-silicon electrical steel strip.

[0026] The thin-gauge high-silicon electrical steel strip has a thickness of 0.30 mm, a magnetic induction intensity B800 of 1.44 T, and a magnetic hysteresis coefficient of 0.5 × 10⁻⁶. -6 .

[0027] Example 2 This embodiment provides a thin-gauge high-silicon electrical steel strip, the preparation method of which includes the following steps: (1) Smelting and casting: The metal raw materials are initially smelted using a converter or electric furnace. The alloy composition by mass percentage is: Si: 6.5%, C: 0.003%, P: 0.001%, S: 0.002%, Al: 0.05%, Mn: 0.15%, Cu: 0.1%, B: 0.007%, with the remainder being Fe and unavoidable impurity elements. After initial smelting, the carbon content of the molten steel is controlled at 0.07%, and the tapping temperature is 1700℃. Subsequently, the molten steel is transferred to a refining furnace for purification. The furnace cavity vacuum is 60Pa, and the temperature is constant for 30min. After refining, the carbon content is 40ppm. The refined molten steel is then injected into a continuous casting machine to form a billet. The casting temperature of the molten steel should be kept at 50℃ for superheating, and the billet thickness is 300mm. (2) Hot rolling and normalizing: The billet is uniformly heated at 1400℃ and held at that temperature for 10 hours. After the holding temperature is reached, it is subjected to multi-pass reversible high-reduction rough rolling at 1300℃, followed by finish rolling at 1000℃. The final rolling temperature is about 1000℃, the thickness of the hot-rolled plate is 3mm, and the coiling temperature is 650℃. The hot-rolled coil is placed in a normalizing furnace for normalizing treatment at 1100℃ for 10 minutes. After normalizing, it is air-cooled to room temperature. (3) Pickling and cold rolling: Hydrochloric acid solution is used to remove iron oxide scale from the surface of hot-rolled plate. The concentration of hydrochloric acid solution is 30% and the temperature is 90℃. After pickling, multiple passes of cold rolling are used to reduce the thickness to the final thickness. The cold rolling reduction rate is >80%, the rolling passes are 7, and the rolling tensile stress is 200MPa. (4) Decarburization and secondary recrystallization annealing: The cold-rolled strip is placed in a continuous annealing furnace at an annealing temperature of 850℃. The protective gas atmosphere is a mixture of hydrogen and nitrogen with a hydrogen component of 60%. Water vapor is added, and the dew point is strictly controlled at +40℃ to +60℃. The holding time is 10 min. After the decarburization annealing, the steel coil is subjected to long-term secondary recrystallization annealing in the annealing furnace at an annealing temperature of 1250℃. The protective gas atmosphere is high-purity hydrogen. The pressure inside the annealing furnace is 0.10 MPa. The holding time is 20 h. After the annealing, the steel coil is cooled to 800℃ in the furnace at a cooling rate of ≤40℃ / h. Then it is naturally cooled to room temperature, and the grain-oriented silicon steel base material is collected. (5) High-pressure solid powder infiltration: The stains and oxide layer on the surface of the grain-oriented silicon steel base material are removed by water washing brush rollers and light acid washing. The cleaned grain-oriented silicon steel base material coil is placed in the infiltration furnace. The winding density of the base material is 6 g / cm³. 3 Diatomaceous earth powder with a diameter of 20 nm was sprayed into the silicon infiltration furnace cavity at a spraying pressure of 0.6 MPa. The mass ratio of silicon oxide powder to silicon steel base material was 1:10. The silicon infiltration temperature was 1200℃, the holding time was 20 h, the protective gas atmosphere was high-purity argon with added water vapor, the dew point was strictly controlled at -20℃ to -10℃, and the furnace cavity pressure was 0.2 MPa. (6) Low-temperature homogenization: After cleaning the surface of the silicon-infiltrating base material by ultrasonic vibration and water washing roller, it is placed in a bell-type furnace for homogenization treatment. The annealing temperature is 400℃, the holding time is 5h, the protective atmosphere is high-purity argon, and the furnace pressure is 0.6MPa to obtain the thin-gauge high-silicon electrical steel strip.

[0028] The thin-gauge high-silicon electrical steel strip material has a thickness of 0.03 mm, a magnetic induction intensity B800 of 1.33 T, and a magnetic hysteresis coefficient of 0.44 × 10⁻⁶. -6 .

[0029] Example 3 This embodiment provides a thin-gauge high-silicon electrical steel strip, the preparation method of which includes the following steps: (1) Smelting and casting: The metal raw materials are initially smelted using a converter or electric furnace. The alloy composition by mass percentage is: Si: 6.5%, C: 0.001%, P: 0.001%, S: 0.001%, Al: 0.033%, Mn: 0.055%, Cu: 0.03%, B: 0.004%, with the remainder being Fe and unavoidable impurity elements. After initial smelting, the carbon content of the molten steel is controlled at 0.01%, and the tapping temperature is 1610℃. Subsequently, the molten steel is transferred to a refining furnace for purification. The furnace cavity vacuum is 40Pa, and the temperature is constant for 15min. After refining, the carbon content is 30ppm. The refined molten steel is injected into a continuous casting machine to form a billet. The casting temperature of the molten steel should be kept at 30℃ for superheating, and the billet thickness is 120mm. (2) Hot rolling and normalizing: The billet was uniformly heated at 1170℃ and held at that temperature for 4.5 hours. After the holding temperature was reached, it was subjected to multi-pass reversible high-reduction rough rolling at 1100℃, followed by finish rolling at 980℃. The final rolling temperature was approximately 840℃, the thickness of the hot-rolled plate was 2.7 mm, and the coiling temperature was 550℃. The hot-rolled coil was placed in a normalizing furnace for normalizing treatment at 1100℃ for 4 minutes. After normalizing, it was air-cooled to room temperature. (3) Pickling and cold rolling: Hydrochloric acid solution is used to remove iron oxide scale from the surface of hot-rolled plate. The concentration of hydrochloric acid solution is 22% and the temperature is 60℃. After pickling, multiple passes of cold rolling are used to reduce the thickness to the final thickness. The cold rolling reduction rate is >80%, the rolling passes are 5, and the rolling tensile stress is 110MPa. (4) Decarburization and secondary recrystallization annealing: The cold-rolled strip is placed in a continuous annealing furnace at an annealing temperature of 810℃. The protective gas atmosphere is a mixture of hydrogen and nitrogen with a hydrogen component of 40%. Water vapor is added, and the dew point is strictly controlled at +40℃ to +60℃. The holding time is 6 minutes. After the decarburization annealing, the steel coil is subjected to long-term secondary recrystallization annealing in the annealing furnace at an annealing temperature of 1170℃. The protective gas atmosphere is high-purity hydrogen. The pressure inside the annealing furnace is 0.03 MPa. The holding time is 8 hours. After the annealing, the steel coil is cooled to 800℃ in the furnace at a cooling rate of ≤40℃ / h. Then it is naturally cooled to room temperature, and the grain-oriented silicon steel base material is collected. (5) High-pressure solid powder infiltration: The stains and oxide layer on the surface of the grain-oriented silicon steel base material are removed by water washing brush rollers and light acid washing. The cleaned grain-oriented silicon steel base material coil is placed in the infiltration furnace. The winding density of the base material is 4.7 g / cm³. 3 Crystal and silica powder with a diameter of 10nm were sprayed into the silicon infiltration furnace chamber at a spraying pressure of 0.5MPa. The mass ratio of silicon oxide powder to silicon steel base material was 1:10. The silicon infiltration temperature was 1030℃, the holding time was 17h, the protective gas atmosphere was high-purity argon with added water vapor, the dew point was strictly controlled at -20℃ to -10℃, and the furnace chamber pressure was 0.2MPa. (6) Low-temperature homogenization: After cleaning the surface of the silicon-infiltrating base material by ultrasonic vibration and water washing roller, it is placed in a bell furnace for homogenization treatment. The annealing temperature is 330℃, the holding time is 4h, the protective atmosphere is high-purity argon, and the furnace pressure is 0.5MPa to obtain the thin-gauge high-silicon electrical steel strip.

[0030] The thin-gauge high-silicon electrical steel strip has a thickness of 0.15 mm, a magnetic induction intensity B800 of 1.47 T, and a magnetic hysteresis coefficient of 0.1 × 10⁻⁶. -6 .

[0031] Example 4 This embodiment provides a thin-gauge high-silicon electrical steel strip, the preparation method of which includes the following steps: (1) Smelting and casting: The metal raw materials are initially smelted using a converter or electric furnace. The alloy composition by mass percentage is: Si: 5.5%, C: 0.002%, P: 0.001%, S: 0.001%, Al: 0.03%, Mn: 0.03%, Cu: 0.06%, B: 0.005%, with the remainder being Fe and unavoidable impurity elements. After initial smelting, the carbon content of the molten steel is controlled at 0.02%, and the tapping temperature is 1650℃. Subsequently, the molten steel is transferred to a refining furnace for purification. The furnace cavity vacuum is 80Pa, and the temperature is constant for 20min. After refining, the carbon content is 40ppm. The refined molten steel is injected into a continuous casting machine to form a billet. The casting temperature of the molten steel should be kept at 30℃ for superheating, and the billet thickness is 70mm. (2) Hot rolling and normalizing: The billet is uniformly heated at 1200℃ and held at that temperature for 5 hours. After the holding temperature is reached, it is subjected to multi-pass reversible high-reduction rough rolling at 1100℃, followed by finish rolling at 950℃. The final rolling temperature is about 820℃, the thickness of the hot-rolled plate is 2.4mm, and the coiling temperature is 500℃. The hot-rolled coil is placed in a normalizing furnace for normalizing treatment at 1100℃ for 5 minutes. After normalizing, it is air-cooled to room temperature. (3) Pickling and cold rolling: Hydrochloric acid solution is used to remove iron oxide scale from the surface of hot-rolled plate. The concentration of hydrochloric acid solution is 20% and the temperature is 60℃. After pickling, multiple passes of cold rolling are used to reduce the thickness to the final thickness. The cold rolling reduction rate is >80%, the rolling passes are 6, and the rolling tensile stress is 110MPa. (4) Decarburization and secondary recrystallization annealing: The cold-rolled strip is placed in a continuous annealing furnace at an annealing temperature of 810℃. The protective gas atmosphere is a mixture of hydrogen and nitrogen with a hydrogen component of 40%. Water vapor is added, and the dew point is strictly controlled at +40℃ to +60℃. The holding time is 5 minutes. After the decarburization annealing, the steel coil is subjected to long-term secondary recrystallization annealing in the annealing furnace at an annealing temperature of 1200℃. The protective gas atmosphere is high-purity hydrogen. The pressure inside the annealing furnace is 0.08 MPa. The holding time is 8 hours. After the annealing, the steel coil is cooled to 800℃ in the furnace at a cooling rate of ≤40℃ / h. Then it is naturally cooled to room temperature, and the grain-oriented silicon steel base material is collected. (5) High-pressure solid powder infiltration: The stains and oxide layer on the surface of the grain-oriented silicon steel base material are removed by water washing brush rollers and light acid washing. The cleaned grain-oriented silicon steel base material coil is placed in the infiltration furnace. The winding density of the base material is 5.2 g / cm³. 3 Diatomaceous earth and silica gel powder with a diameter of 12nm were sprayed into the silicon infiltration furnace cavity at a spraying pressure of 0.5MPa. The mass ratio of silicon oxide powder to silicon steel base material was 1:10. The silicon infiltration temperature was 1000℃, the holding time was 14h, the protective gas atmosphere was high-purity argon with added water vapor, the dew point was strictly controlled at -20℃ to -10℃, and the furnace cavity pressure was 0.2MPa. (6) Low-temperature homogenization: After cleaning the surface of the silicon-infiltrating base material by ultrasonic vibration and water washing roller, it is placed in a bell furnace for homogenization treatment. The annealing temperature is 300℃, the holding time is 3h, the protective atmosphere is high-purity argon, and the furnace pressure is 0.5MPa to obtain the thin-gauge high-silicon electrical steel strip.

[0032] The thin-gauge high-silicon electrical steel strip has a thickness of 0.22 mm, a magnetic induction intensity B800 of 1.46 T, and a magnetic hysteresis coefficient of 0.3 × 10⁻⁶. -6 .

[0033] Comparative Example 1 This comparative example provides an electrical steel strip, which differs from Example 3 in step (1): In step (1), the Si element content is 7%. The strip has a large deformation resistance accumulated during the cold rolling process, and serious problems such as edge cracks and strip breakage are not possible to process into continuous strip.

[0034] Comparative Example 2 This comparative example provides an electrical steel strip, which differs from Example 3 in step (5): In step (5), the silicon oxide powder has a particle size ≥ 50 μm.

[0035] Due to the large particle size of silica powder, the oriented silicon steel base material forms a large surface energy on the surface during the low-temperature silicon infiltration process, which destroys the original Goss texture of the base material, resulting in a magnetic induction of only 1.26T for the oriented high silicon steel B800.

[0036] Comparative Example 3 This comparative example provides an electrical steel strip, which differs from Example 3 in step (5): In step (5), the high-voltage solid powder-coated silicon-infiltrated substrate winding density is 6.5 g / cm³. 3 The mass ratio of silicon oxide powder to silicon steel base material is 1:40, and the furnace pressure is 0.1 MPa.

[0037] The penetration ratio of silicon (Si) on the surface of silicon steel base material is relatively low, resulting in a low silicon content in high-silicon electrical steel. Consequently, the magnetic hysteresis coefficient of the finished high-silicon steel is 0.8 × 10⁻⁶. -6 .

[0038] As can be seen from the above data, Examples 1-4 all yielded electrical steel strips with high magnetic induction intensity and low hysteresis coefficient, and the thickness of the electrical steel strips was controlled within 0.03~0.30mm. This is due to the strict use of 1-20nm nanoscale silicon oxide powder and precise control of process parameters such as the winding density of the base material, the powder ratio, and the furnace pressure. Among them, the parameter combination in Example 3 ensured that there were appropriate gaps between the layers of the roll material, which facilitated the flow of the silicon diffusion atmosphere and powder penetration; there was a sufficient concentration of silicon source supply; and an appropriate high-pressure environment promoted diffusion, thereby achieving effective and sufficient silicon diffusion and the lowest hysteresis coefficient (0.1×10). -6 ).

[0039] Figures 1-3 The images show the microstructure and texture morphology of the thin-gauge high-silicon electrical steel strips obtained in Examples 1, 2, and 3 of this invention, respectively. Coarse, uniform equiaxed grains can be observed, indicating that the base material has successfully undergone secondary recrystallization. The right side shows the ODF diagram of the thin-gauge high-silicon electrical steel strip. φ1, Φ, and φ2 represent the rotation relationship between the crystal coordinate system and the sample coordinate system, with φ2 = 45°. It can be seen that significant {100} morphology exists in Examples 1 and 2. <100> Texture and {111} <112> Texture, in Example 2 {100} <100> Texture strength increased to 30, {111} <112> The texture intensity decreased to 6, while in Example 3 the texture intensity was further enhanced, forming a grain structure that is beneficial to magnetic properties.

[0040] In Comparative Example 1, the high silicon content (>6.5%) led to a sharp increase in material brittleness, making it unsuitable for traditional cold rolling processes. Comparative Example 2 used larger silica powder particle sizes, resulting in significant surface energy on the surface of the oriented silicon steel base material during low-temperature silicon diffusion. This disrupted the original Goss texture of the base material, leading to deterioration in magnetic properties. In Comparative Example 3, tight winding and insufficient furnace pressure hindered the uniform flow and penetration of the silicon diffusion atmosphere. An excessively low powder ratio meant insufficient available silicon source. These factors combined resulted in insufficient and uneven silicon diffusion into the base material matrix. Uneven silicon content distribution generated significant internal stress, leading to an increased hysteresis coefficient during magnetization and deterioration in product performance.

[0041] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a thin-gauge high-silicon electrical steel strip, characterized in that, Includes the following steps: The raw materials are smelted and cast to obtain a billet; The billet is hot-rolled to obtain a hot-rolled plate, which is then normalized. The normalized hot-rolled plate is pickled and then subjected to multiple cold rolling passes with a cold rolling reduction rate of >80% to obtain cold-rolled strip. The cold-rolled strip is subjected to decarburization annealing and secondary recrystallization annealing to obtain oriented silicon steel base material; The oriented silicon steel base material is placed in a silicon diffusion furnace, and nano-sized silicon oxide powder is sprayed into the furnace cavity. Silicon diffusion treatment is carried out under the conditions of 800℃~1200℃ and furnace cavity pressure of 0.1~0.2MPa. The silicon-infiltrated base material is homogenized at 200-400°C in a protective atmosphere to obtain the thin-gauge high-silicon electrical steel strip.

2. The preparation method according to claim 1, characterized in that, The process parameters for the silicon infiltration treatment satisfy one or more of the following: The mass ratio of the silicon oxide powder to the oriented silicon steel base material is 1:10; The powder injection pressure is 0.3~0.6MPa; The protective gas is high-purity argon, and the dew point is controlled at -20℃ to -10℃; The heat preservation time is 8h~20h; The base material winding density is 4~6 g / cm³. 3 .

3. The preparation method according to claim 2, characterized in that, The silicon oxide powder has a particle diameter of 1~20nm.

4. The preparation method according to claim 3, characterized in that, The silicon oxide powder is one or more of quartz, crystal, silica, diatomaceous earth, and silica gel.

5. The preparation method according to claim 1, characterized in that, The furnace pressure for homogenization treatment is 0.3~0.6MPa, and the holding time is 2h~5h.

6. The preparation method according to claim 1, characterized in that, The hot rolling specifically includes: heating the billet at a uniform temperature of 1100℃~1400℃ for 3~10 hours; rough rolling at 1000~1300℃, followed by finish rolling at 900~1000℃, with a final rolling temperature of 800~1000℃, to obtain a hot-rolled plate with a thickness of 2~3mm, and a coiling temperature of 400~650℃.

7. The preparation method according to claim 1, characterized in that, The pickling process uses a hydrochloric acid solution with a concentration of 10% to 30% and a temperature of 50 to 90°C; the cold rolling process consists of 3 to 7 passes, with a rolling tensile stress of 80 to 200 MPa.

8. The preparation method according to claim 1, characterized in that, The decarburization annealing temperature is 700℃~850℃, the holding time is 1~10min, and the protective gas is a mixture of hydrogen and nitrogen. In the hydrogen-nitrogen mixture, the hydrogen component is 30% to 60%, and water vapor is added to control the dew point to be +40℃ to +60℃.

9. The preparation method according to claim 1, characterized in that, The secondary recrystallization annealing is performed at a temperature of 1100℃~1250℃, with high-purity hydrogen as the protective gas, a furnace pressure of 0.01MPa~0.10MPa, and a holding time of 4h~20h.

10. The preparation method according to claim 1, characterized in that, The raw materials, by mass percentage, include: Si: 3.5%~6.5%, C: ≤0.005%, P: ≤0.003%, S: ≤0.003%, Al: 0.01%~0.05%, Mn: 0.03%~0.15%, Cu: 0.01%~0.1%, B: 0.002%~0.007%, with the remainder being Fe and unavoidable impurity elements.

11. A thin-gauge high-silicon electrical steel strip prepared by the preparation method according to any one of claims 1 to 10.

12. The thin-gauge high-silicon electrical steel strip according to claim 11, characterized in that, The thickness of the thin-gauge high-silicon electrical steel strip is 0.03~0.30mm.

13. The thin-gauge high-silicon electrical steel strip according to claim 11, characterized in that, The magnetic induction intensity B800 of the thin-gauge high-silicon electrical steel strip is ≥1.33T; and / or The hysteresis coefficient of the thin-gauge high-silicon electrical steel strip is ≤0.5×10. -6 .

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