Preparation method of low-iron-loss high-magnetic-induction-intensity oriented silicon steel coil

Abstract

The invention discloses a preparation method of an oriented silicon steel coil with low iron loss and high magnetic induction intensity. The preparation method comprises the following steps: step 1, component gradient design; 2, multi-stage rolling texture regulation and control; step 3, electromagnetic field-assisted annealing; step 4, surface treatment and post-processing; 5, precise shearing and finished product detection; and step 6, performing environment-friendly cooling and packaging. The rolling difficulty is reduced through cooperation of component gradient design and multi-stage rolling, and the yield is increased by 12% or above; the electromagnetic field-assisted annealing technology improves the Gaussian texture proportion to 92% and improves the grain size uniformity by 30%; the iron loss P1.7 / 50 of the final product is as low as 0.72 W / kg, and the magnetic induction intensity B8 reaches 2.02 T, which are respectively reduced by 15% and improved by 3% compared with the traditional process; the complex process system realizes precise control and stability improvement of the production process through intelligent parameter regulation and control.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of grain-oriented silicon steel coils, and specifically provides a method for preparing a grain-oriented silicon steel coil with low iron loss and high magnetic induction intensity. Background Art

[0002] ‌Grain-oriented silicon steel‌ is a special electrical steel, in which the easy magnetization direction of the grains is parallel to the rolling direction, and the silicon content is about 3%. Grain-oriented silicon steel is mainly divided into two categories: common grain-oriented silicon steel (CGO) and high magnetic induction grain-oriented silicon steel (HiB). Grain-oriented silicon steel is widely used in the power, electronics and military industries, and is an important material in power generation equipment, power transmission and transformation equipment, and various electrical equipment. High-grade silicon steel products are even more important. They are not only basic raw materials, but also the key driving force to help the whole society achieve green transformation.

[0003] With the global demand for energy efficiency improvement, the low iron loss and high magnetic induction performance of grain-oriented silicon steel have become the focus of research. When discussing traditional processes, some significant bottleneck problems have to be faced: 1) The contradiction between silicon content and processing performance, which significantly increases the risk of cracks during rolling; 2) When using a single annealing process, it is found that it is difficult to optimize the orientation and size of grains simultaneously, which limits the improvement of material properties; 3) At present, the means of texture control are relatively limited, resulting in an insufficient proportion of Goss texture in the material, which affects the overall performance of the material. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a grain-oriented silicon steel coil with low iron loss and high magnetic induction intensity, so as to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A method for preparing a grain-oriented silicon steel coil with low iron loss and high magnetic induction intensity, specifically including the following steps: Step 1. Composition gradient design: Adopt a three-layer gradient composition structure, and the thickness ratios from the surface layer to the core of the steel coil are: the surface layer thickness ratio is 20%, the intermediate layer thickness ratio is 60%, and the core layer thickness ratio is 20%; Step 2. Multi-stage rolling texture control: including slab pretreatment, hot rolling composite deformation and cold rolling gradient deformation respectively; Step 3. Electromagnetic field-assisted annealing: First, perform primary annealing for texture activation. After the primary annealing is completed, perform decarburization annealing with precise atmosphere control. After the decarburization annealing is completed, finally perform high-temperature annealing with multi-field coupling regulation; Step 4. Surface treatment and post-processing: Treat the steel coil after high-temperature annealing by electrochemical etching, and apply a double-layer insulating coating after treatment; Step 5: Precision Shearing and Final Product Inspection: The surface-treated steel coil is precisely sheared to obtain finished low-iron-loss and high-magnetic-induction-orientation silicon steel coils that meet the specifications. Subsequently, a comprehensive inspection of the finished products is carried out. Step 6: Environmentally Friendly Cooling and Packaging: After precision shearing and final product inspection are completed, an environmentally friendly coolant is used to rapidly cool the steel coil. This coolant can not only effectively reduce the temperature of the steel coil and prevent performance fluctuations caused by temperature changes during storage and transportation, but also its components are biodegradable and have minimal impact on the environment. Subsequently, the steel coil is packaged in special moisture-proof and dust-proof packaging materials to ensure that the product remains in the best condition before reaching the end user.

[0006] Preferably, the chemical composition of the surface layer in step 1 is by mass percentage: Si 3.3 - 3.5%, Mn 0.12 - 0.15%, Al 0.04 - 0.05%, Sn 0.02 - 0.03%, and the balance is Fe and unavoidable impurities. The chemical composition of the intermediate layer is by mass percentage: Si 3.0 - 3.2%, Mn 0.08 - 0.10%, Al 0.02 - 0.03%, Sn 0.01 - 0.02%, and the balance is Fe and unavoidable impurities. The chemical composition of the core is by mass percentage: Si 2.8 - 3.0%, Mn 0.05 - 0.07%, Al 0.01 - 0.02%, Sn 0.005 - 0.01%, and the balance is Fe and unavoidable impurities.

[0007] Preferably, the chemical composition of the surface layer is preferably by mass percentage: Si 3.4%, Mn 0.13%, Al 0.05%, Sn 0.02%, and the balance is Fe and unavoidable impurities. The chemical composition of the intermediate layer is preferably by mass percentage: Si 3.1%, Mn 0.09%, Al 0.03%, Sn 0.01%, and the balance is Fe and unavoidable impurities. The chemical composition of the core is preferably by mass percentage: Si 2.9%, Mn 0.06%, Al 0.02%, Sn 0.001%, and the balance is Fe and unavoidable impurities.

[0008] Preferably, the chemical composition of the surface layer is preferably by mass percentage: Si 3.5%, Mn 0.15%, Al 0.05%, Sn 0.03%, and the balance is Fe and unavoidable impurities. The chemical composition of the intermediate layer is preferably by mass percentage: Si 3.2%, Mn 0.10%, Al 0.03%, Sn 0.02%, and the balance is Fe and unavoidable impurities. The chemical composition of the core part is preferably by mass percentage: Si 3.0%, Mn 0.07%, Al 0.02%, Sn 0.01%, and the balance is Fe and inevitable impurities.

[0009] Preferably, in the second step, the billet pretreatment is specifically as follows: The electromagnetic stirring technology is adopted to eliminate composition segregation, and then ultrasonic flaw detection is carried out to detect internal defects. The electromagnetic stirring frequency is 50 Hz, and the current intensity is 300 A; then the billet is heated to 1320 - 1350 °C and kept warm for 4 hours to promote the homogenization of alloying elements through high-temperature diffusion; The hot-rolled composite deformation specifically includes the following steps: The first-stage hot rolling: The starting rolling temperature is 1280 °C, asynchronous rolling is adopted, the upper and lower roll speed ratio is 1.15:1, the reduction ratio of the first two passes is 25% each, and shear deformation is introduced to promote the formation of γ fiber texture; The second-stage hot rolling: The finishing rolling temperature is 880 - 900 °C, equal-diameter rolling is adopted, the reduction ratio of the last three passes decreases, 20% → 15% → 10%, and part of the non-recrystallized structure is retained to refine the grains; After hot rolling, water spray quenching is adopted, the water pressure is 5 MPa, the water temperature is 20 °C, and the cooling rate is controlled at 150 °C / s to inhibit the precipitation of coarse carbides; The cold-rolled gradient deformation adopts a four-high reversible rolling mill and is cold-rolled in three stages, specifically including the following steps: The rough rolling stage: The reduction ratio is 70%, the rolling speed is 200 m / min, and a strong α fiber texture is formed; The middle rolling stage: Intermediate annealing, after annealing to 750 °C and keeping warm for 1 hour, the reduction ratio is 60%, the rolling speed is 150 m / min, and plane strain compression is introduced; The finish rolling stage: The final reduction ratio is 40%, the rolling speed is 100 m / min, through roll profile optimization, the work roll crown is 0.05 mm, the sheet shape is controlled, and the final thickness is 0.23 mm.

[0010] Preferably, the primary annealing in the third step is specifically as follows: Heat to 850 °C in an alternating magnetic field with a magnetic field strength of 0.5 T and a frequency of 20 kHz, and keep warm for 2 hours to promote the selective growth of favorable texture by the magnetostrictive effect; The decarburization annealing is specifically as follows: Adopt a wet hydrogen atmosphere, the H2O content is 3 - 5 vol%, heat to 950 °C at a rate of 5 °C / min, and keep warm for 1.5 hours to reduce the carbon content to less than 0.0015% through the hydrogen-oxygen reaction; The high-temperature annealing is specifically as follows: In a vacuum of 1×10 -3In a Pa environment, a DC magnetic field and an AC electric field are applied, and the temperature is raised to 1180°C at a rate of 3°C / min and kept at this temperature for 6 hours. The DC magnetic field intensity is 1.2T, the AC electric field voltage is 50V, and the frequency is 100Hz; then it enters the slow cooling stage, and ultrasonic vibration is introduced in the slow cooling stage to promote the preferential growth of Gaussian texture and inhibit abnormal grain growth. The cooling rate in the slow cooling stage is 2°C / min, the power of ultrasonic vibration is 2kW, and the frequency is 20kHz.

[0011] Preferably, the electrochemical etching in step 4 is specifically performed by using electrochemical etching technology, the electrolyte is 10% HNO3 + 5% HF aqueous solution, the etching depth is 5-8 μm, and the surface stress concentration area is removed; The double-layer insulation coating is specifically applied with a bottom layer of nano-SiO2 sol with a thickness of 1-2μm and a surface layer of phosphate coating with a thickness of 3-5μm to improve corrosion resistance and insulation performance.

[0012] Preferably, step five includes but is not limited to magnetic property testing, iron loss testing and microstructure analysis to ensure that each batch of finished products can meet the predetermined performance indicators; in addition, the finished products are regularly sampled and re-inspected to continuously monitor production quality, adjust the production process in a timely manner, and maintain the stability and consistency of product performance.

[0013] Preferably, in step six, detailed product information and traceability codes are attached to the packaging materials to facilitate users to understand product performance and production batches, thereby enhancing product traceability and transparency.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The composition gradient design and multi-stage rolling work together to reduce the difficulty of rolling and increase the yield rate by more than 12%; the electromagnetic field assisted annealing technology increases the proportion of Gaussian texture to 92% and the grain size uniformity by 30%; the final product's iron loss P1.7 / 50 is as low as 0.72W / kg, and the magnetic induction intensity B8 reaches 2.02T, which are 15% lower and 3% higher than the traditional process respectively; the complex process system achieves precise control and improved stability of the production process through intelligent parameter regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flow chart of the method of the present invention; Figure 2 This is the process flow chart of the multi-stage rolling texture control process of the present invention Figure 3 It is a schematic diagram of the electromagnetic field assisted annealing principle of the present invention. DETAILED DESCRIPTION

[0016] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0017] Please refer to Figures 1-3 , the present invention provides a preparation method for low-iron-loss and high-magnetic-induction-strength grain-oriented silicon steel coils, specifically including the following steps: Step 1. Composition gradient design: Adopt a three-layer gradient composition structure, and the thickness ratios from the surface layer to the core of the steel coil are as follows: the surface layer thickness ratio is 20%, the intermediate layer thickness ratio is 60%, and the core thickness ratio is 20%; the chemical composition of the surface layer by mass percentage is: Si 3.3 - 3.5%, Mn 0.12 - 0.15%, Al 0.04 - 0.05%, Sn 0.02 - 0.03%, and the balance is Fe and unavoidable impurities; The chemical composition of the intermediate layer by mass percentage is: Si 3.0 - 3.2%, Mn 0.08 - 0.10%, Al 0.02 - 0.03%, Sn 0.01 - 0.02%, and the balance is Fe and unavoidable impurities; The chemical composition of the core by mass percentage is: Si 2.8 - 3.0%, Mn 0.05 - 0.07%, Al 0.01 - 0.02%, Sn 0.005 - 0.01%, and the balance is Fe and unavoidable impurities; Step 2. Multi-stage rolling texture control: It respectively includes billet pretreatment, hot rolling composite deformation, and cold rolling gradient deformation; the specific billet pretreatment is: adopt electromagnetic stirring technology to eliminate composition segregation, and then conduct ultrasonic flaw detection to detect internal defects. The electromagnetic stirring frequency is 50 Hz, and the current intensity is 300 A; then heat the billet to 1320 - 1350 °C and hold for 4 hours to promote the homogenization of alloy elements through high-temperature diffusion; The hot rolling composite deformation specifically includes the following steps: The first-stage hot rolling: The starting rolling temperature is 1280 °C, adopt asynchronous rolling, the upper and lower roll speed ratio is 1.15:1, and the reduction ratio of the first two passes is 25% each, introducing shear deformation to promote the formation of γ fiber texture; The second-stage hot rolling: The final rolling temperature is 880 - 900 °C, adopt equal-diameter rolling, and the reduction ratio of the last three passes decreases, 20% → 15% → 10%, retaining some non-recrystallized tissues to refine the grains; After hot rolling, water spray quenching is adopted, the water pressure is 5 MPa, the water temperature is 20 °C, and the cooling rate is controlled at 150 °C / s to inhibit the precipitation of coarse carbides; The cold rolling gradient deformation uses a four-high reversible rolling mill and is carried out in three stages of cold rolling, specifically including the following steps: Rough rolling stage: The reduction ratio is 70%, the rolling speed is 200 m / min, and a strong α fiber texture is formed; Intermediate rolling stage: Intermediate annealing is carried out. After annealing to 750 °C and holding for 1 hour, the reduction ratio is 60%, the rolling speed is 150 m / min, and plane strain compression is introduced; Finish rolling stage: The final rolling reduction ratio is 40%, the rolling speed is 100 m / min. Through roll profile optimization, the crown of the work roll is 0.05 mm to control the sheet shape, and the final thickness is 0.23 mm; Step 3: Electromagnetic field-assisted annealing: First, carry out primary annealing for texture activation. After the primary annealing is completed, carry out decarburization annealing with precise atmosphere control. After the decarburization annealing is completed, finally carry out high-temperature annealing with multi-field coupling regulation; The primary annealing is specifically carried out by heating to 850 °C in an alternating magnetic field with a magnetic field strength of 0.5 T and a frequency of 20 kHz, holding for 2 hours, and using the magnetostrictive effect to promote the selective growth of favorable textures; The decarburization annealing is specifically carried out using a wet hydrogen atmosphere with an H2O content of 3 - 5 vol%, heating to 950 °C at a rate of 5 °C / min, holding for 1.5 hours, and reducing the carbon content to less than 0.0015% through the hydrogen-oxygen reaction; The high-temperature annealing is specifically carried out in an environment with a vacuum degree of 1×10 -3 Pa, applying a DC magnetic field and an AC electric field, heating to 1180 °C at a rate of 3 °C / min, holding for 6 hours, the DC magnetic field strength is 1.2 T, the AC electric field voltage is 50 V, and the frequency is 100 Hz; Then enter the slow cooling stage. The slow cooling stage introduces ultrasonic vibration to promote the preferred growth of the Gaussian texture, inhibit abnormal grain growth. The cooling rate in the slow cooling stage is 2 °C / min, the power of the ultrasonic vibration is 2 kW, and the frequency is 20 kHz; Step 4: Surface treatment and post-processing: The steel coil after high-temperature annealing is treated by electrochemical etching, and a double-layer insulating coating is applied after treatment; The electrochemical etching is specifically carried out using electrochemical etching technology, the electrolyte is a 10% HNO3 + 5% HF aqueous solution, the etching depth is 5 - 8 μm, and the surface stress concentration area is removed; Applying the double-layer insulating coating is specifically that the bottom layer is a nano-SiO2 sol with a thickness of 1 - 2 μm, and the surface layer is a phosphate coating with a thickness of 3 - 5 μm to improve the corrosion resistance and insulation performance; Step Five: Precision Shearing and Final Product Inspection: The surface-treated steel coils are precisely sheared to obtain finished low-iron-loss and high-magnetic-induction-strength grain-oriented silicon steel coils that meet the specifications. Subsequently, comprehensive inspections are carried out on the finished products, including but not limited to magnetic property testing, iron loss testing, and microstructure analysis, to ensure that each batch of finished products can meet the predetermined performance indicators. In addition, regular sampling and re-inspection of the finished products are carried out to continuously monitor the production quality, promptly adjust the production process, and maintain the stability and consistency of product performance. Step Six: Environmentally Friendly Cooling and Packaging: After precision shearing and final product inspection are completed, the steel coils are rapidly cooled using an environmentally friendly coolant. This coolant can not only effectively reduce the temperature of the steel coils and prevent performance fluctuations caused by temperature changes during storage and transportation, but also its components are biodegradable and have minimal impact on the environment. Subsequently, the steel coils are packaged in special moisture-proof and dust-proof packaging materials to ensure that the products remain in the best condition before reaching the end-users. Detailed product information and traceability codes are attached to the packaging materials to facilitate users' understanding of product performance and production batches, enhancing the traceability and transparency of the products. Embodiment

[0018] A method for preparing low-iron-loss and high-magnetic-induction-strength grain-oriented silicon steel coils specifically includes the following steps: Step One: Composition Gradient Design: A three-layer gradient composition structure is adopted, and the thickness ratios from the surface layer to the core of the steel coil are as follows: the surface layer thickness ratio is 20%, the intermediate layer thickness ratio is 60%, and the core layer thickness ratio is 20%. The chemical composition of the surface layer by mass percentage is: Si 3.4%, Mn 0.13%, Al 0.05%, Sn 0.02%, and the balance is Fe and unavoidable impurities. The chemical composition of the intermediate layer by mass percentage is: Si 3.1%, Mn 0.09%, Al 0.03%, Sn 0.01%, and the balance is Fe and unavoidable impurities. The chemical composition of the core layer by mass percentage is: Si 2.9%, Mn 0.06%, Al 0.02%, Sn 0.001%, and the balance is Fe and unavoidable impurities. Step Two: Multi-stage Rolling Texture Control: It includes billet pretreatment, hot rolling composite deformation, and cold rolling gradient deformation respectively. The billet pretreatment is specifically as follows: The electromagnetic stirring technology is used to eliminate composition segregation, and then ultrasonic flaw detection is carried out to detect internal defects. The electromagnetic stirring frequency is 50 Hz, and the current intensity is 300 A. Then the billet is heated to 1350 °C and held for 4 hours to promote the homogenization of alloying elements through high-temperature diffusion. The hot rolling composite deformation specifically includes the following steps: First-stage hot rolling: The starting rolling temperature is 1280 °C. Asynchronous rolling is adopted, and the upper and lower roll speed ratio is 1.15:1. The reduction ratios for the first two passes are each 25%. Shear deformation is introduced to promote the formation of γ fiber texture; Second-stage hot rolling: The finishing rolling temperature is 890 °C. Equal-diameter rolling is adopted, and the reduction ratios for the last three passes decrease, 20% → 15% → 10%. Part of the unrecrystallized structure is retained to refine the grains; After hot rolling, water spray quenching is carried out. The water pressure is 5 MPa, the water temperature is 20 °C, and the cooling rate is controlled at 150 °C / s to inhibit the precipitation of coarse carbides; For cold rolling gradient deformation, a four-high reversible rolling mill is used and cold rolling is carried out in three stages, which specifically include the following steps: Rough rolling stage: The reduction ratio is 70%, and the rolling speed is 200 m / min to form a strong α fiber texture; Intermediate rolling stage: Intermediate annealing is carried out. After annealing to 750 °C and holding for 1 hour, the reduction ratio is 60%, and the rolling speed is 150 m / min to introduce plane strain compression; Finish rolling stage: The final rolling reduction ratio is 40%, and the rolling speed is 100 m / min. Through roll profile optimization, the work roll crown is 0.05 mm to control the sheet shape, and the final thickness is 0.23 mm; Step 3. Electromagnetic field-assisted annealing: First, primary annealing for texture activation is carried out. After the primary annealing is completed, decarburization annealing with precise atmosphere control is carried out. After the decarburization annealing is completed, finally, high-temperature annealing with multi-field coupling regulation is carried out; Specifically, for the primary annealing, it is heated to 850 °C in an alternating magnetic field with a magnetic field strength of 0.5 T and a frequency of 20 kHz and held for 2 hours. The magnetostrictive effect is used to promote the selective growth of favorable textures; Specifically, for the decarburization annealing, a wet hydrogen atmosphere is adopted, the H2O content is 3 - 5 vol%, it is heated to 950 °C at a rate of 5 °C / min and held for 1.5 hours. The carbon content is reduced to less than 0.0015% through the hydrogen-oxygen reaction; Specifically, for the high-temperature annealing, in an environment with a vacuum degree of 1×10 -3 Pa, a DC magnetic field and an AC electric field are applied. It is heated to 1180 °C at a rate of 3 °C / min and held for 6 hours. The DC magnetic field strength is 1.2 T, the AC electric field voltage is 50 V, and the frequency is 100 Hz; Then it enters the slow cooling stage. Ultrasonic vibration is introduced in the slow cooling stage to promote the preferential growth of Goss texture, inhibit abnormal grain growth. The cooling rate in the slow cooling stage is 2 °C / min, the power of the ultrasonic vibration is 2 kW, and the frequency is 20 kHz; Step 4. Surface treatment and post-processing: Electrochemical etching is used to treat the steel coil after high-temperature annealing, and a double-layer insulating coating is applied after treatment; Specifically, for the electrochemical etching, electrochemical etching technology is adopted, the electrolyte is 10% HNO3 + 5% HF aqueous solution, and the etching depth is 5 - 8 μm to remove the surface stress concentration area; The double-layer insulation coating is specifically a nano-SiO2 sol as the bottom layer with a thickness of 1-2 μm, and a phosphate coating as the surface layer with a thickness of 3-5 μm, which improves the corrosion resistance and insulation performance; Step Five, Precision Shearing and Finished Product Inspection: The surface-treated steel coil is precisely sheared to obtain finished oriented silicon steel coils with low iron loss and high magnetic induction intensity that meet the specifications; Subsequently, a comprehensive inspection of the finished products is carried out, including but not limited to magnetic property testing, iron loss testing, and microstructure analysis, to ensure that each batch of finished products can meet the predetermined performance indicators; In addition, regular sampling re-inspection of the finished products is carried out to continuously monitor the production quality, timely adjust the production process, and maintain the stability and consistency of product performance; Step Six, Environmentally Friendly Cooling and Packaging: After completing precision shearing and finished product inspection, the steel coil is rapidly cooled using an environmentally friendly coolant. This coolant can not only effectively reduce the temperature of the steel coil and prevent performance fluctuations caused by temperature changes during storage and transportation, but also its components are biodegradable and have minimal impact on the environment. Subsequently, the steel coil is packaged in special moisture-proof and dust-proof packaging materials to ensure that the product remains in the best condition before reaching the end user; Detailed product information and traceability codes are attached to the packaging materials to facilitate users to understand the product performance and production batches, enhancing the traceability and transparency of the product. Embodiment

[0019] A preparation method for an oriented silicon steel coil with low iron loss and high magnetic induction intensity specifically includes the following steps: Step One, Composition Gradient Design: A three-layer gradient composition structure is adopted, and the thickness ratios from the surface layer to the core of the steel coil are in turn: the surface layer thickness ratio is 20%, the intermediate layer thickness ratio is 60%, and the core thickness ratio is 20%; The chemical composition of the surface layer by mass percentage is: Si 3.5%, Mn 0.15%, Al 0.05%, Sn 0.03%, and the balance is Fe and unavoidable impurities; The chemical composition of the intermediate layer by mass percentage is: Si 3.2%, Mn 0.10%, Al 0.03%, Sn 0.02%, and the balance is Fe and unavoidable impurities; The chemical composition of the core by mass percentage is: Si 3.0%, Mn 0.07%, Al 0.02%, Sn 0.01%, and the balance is Fe and unavoidable impurities; Step Two, Multi-stage Rolling Texture Control: It respectively includes continuous casting billet pretreatment, hot rolling composite deformation, and cold rolling gradient deformation; The continuous casting billet pretreatment is specifically: The electromagnetic stirring technology is adopted to eliminate composition segregation, and then ultrasonic flaw detection is carried out to detect internal defects. The electromagnetic stirring frequency is 50 Hz, and the current intensity is 300 A; Then the continuous casting billet is heated to 1350 °C and held for 4 hours to promote the homogenization of alloying elements through high-temperature diffusion; The hot-rolling composite deformation specifically includes the following steps: The first-stage hot rolling: The starting rolling temperature is 1280 °C. Asynchronous rolling is adopted, and the upper and lower roll speed ratio is 1.15:1. The reduction ratios of the first two passes are each 25%. Shear deformation is introduced to promote the formation of γ fiber texture; The second-stage hot rolling: The finishing rolling temperature is 900 °C. Equal-diameter rolling is adopted, and the reduction ratios of the last three passes decrease, 20% → 15% → 10%. Part of the non-recrystallized structure is retained to refine the grains; After hot rolling, water spray quenching is adopted. The water pressure is 5 MPa, the water temperature is 20 °C, and the cooling rate is controlled at 150 °C / s to inhibit the precipitation of coarse carbides; The cold-rolling gradient deformation uses a four-high reversible rolling mill and is divided into three stages of cold rolling. Specifically, it includes the following steps: The rough rolling stage: The reduction ratio is 70%, and the rolling speed is 200 m / min to form a strong α fiber texture; The middle rolling stage: Intermediate annealing is carried out. After annealing to 750 °C and holding for 1 hour, the reduction ratio is 60%, and the rolling speed is 150 m / min to introduce plane strain compression; The finish rolling stage: The final reduction ratio is 40%, and the rolling speed is 100 m / min. Through roll profile optimization, the work roll convexity is 0.05 mm to control the sheet shape, and the final thickness is 0.23 mm; Step 3. Electromagnetic field-assisted annealing: First, carry out primary annealing for texture activation. After the primary annealing is completed, carry out decarburization annealing with precise atmosphere control. After the decarburization annealing is completed, finally carry out high-temperature annealing with multi-field coupling regulation; Specifically, for the primary annealing, heat to 850 °C in an alternating magnetic field with a magnetic field strength of 0.5 T and a frequency of 20 kHz, and hold for 2 hours to promote the selective growth of favorable texture by using the magnetostrictive effect; Specifically, for the decarburization annealing, a wet hydrogen atmosphere is adopted, the H2O content is 3 - 5 vol%, heat to 950 °C at a rate of 5 °C / min, and hold for 1.5 hours to reduce the carbon content to less than 0.0015% through the hydrogen-oxygen reaction; Specifically, for the high-temperature annealing, in an environment with a vacuum degree of 1×10 -3 Pa, apply a DC magnetic field and an AC electric field, heat to 1180 °C at a rate of 3 °C / min, and hold for 6 hours. The DC magnetic field strength is 1.2 T, the AC electric field voltage is 50 V, and the frequency is 100 Hz; Then enter the slow cooling stage. Ultrasonic vibration is introduced in the slow cooling stage to promote the preferred growth of Goss texture, inhibit abnormal grain growth. The cooling rate in the slow cooling stage is 2 °C / min, the power of the ultrasonic vibration is 2 kW, and the frequency is 20 kHz; Step 4. Surface treatment and post-processing: The steel coil after high-temperature annealing is treated by electrochemical etching, and then a double-layer insulating coating is applied; specifically, electrochemical etching is carried out by using electrochemical etching technology, the electrolyte is 10% HNO3 + 5% HF aqueous solution, the etching depth is 5 - 8 μm, and the stress concentration area on the surface layer is removed; Specifically, for the application of the double-layer insulating coating, the bottom layer is nano-SiO2 sol with a thickness of 1 - 2 μm, and the surface layer is a phosphate coating with a thickness of 3 - 5 μm, which improves the corrosion resistance and insulation performance; Step 5. Precision shearing and finished product inspection: The surface-treated steel coil is precisely sheared to obtain finished products of grain-oriented silicon steel coils with low iron loss and high magnetic induction intensity that meet the specifications; subsequently, comprehensive inspections are carried out on the finished products, including but not limited to magnetic property testing, iron loss testing, and microstructure analysis, to ensure that each batch of finished products can meet the predetermined performance indicators; in addition, regular sampling re-inspections are carried out on the finished products to continuously monitor the production quality, timely adjust the production process, and maintain the stability and consistency of product performance; Step 6. Environmentally friendly cooling and packaging: After precision shearing and finished product inspection, the steel coil is rapidly cooled by using an environmentally friendly coolant. This coolant can not only effectively reduce the temperature of the steel coil and prevent performance fluctuations caused by temperature changes during storage and transportation, but also its components are biodegradable and have minimal impact on the environment. Subsequently, the steel coil is packaged in a special moisture-proof and dust-proof packaging material to ensure that the product remains in the best condition before reaching the end user; detailed product information and traceability codes are attached to the packaging material to facilitate users to understand the product performance and production batch, enhancing the traceability and transparency of the product.

[0020] The parameters of the grain-oriented silicon steel coils with low iron loss and high magnetic induction intensity prepared by using the above-mentioned Example 1 and Example 2 are shown in the following table after passing the inspection: It can be seen from the comparison that the grain-oriented silicon steel coils with low iron loss and high magnetic induction intensity prepared by using Example 1 and Example 2 of the present invention are superior to the prior art in key performance indicators such as iron loss, magnetic induction intensity, and standard deviation of grain size. This benefits from the unique composition gradient design, multi-stage rolling texture control, electromagnetic field-assisted annealing, and environmentally friendly cooling and packaging and other innovative processes of the present invention. The comprehensive application of these processes not only improves the performance indicators of the silicon steel coil, but also ensures the stability and consistency of the product, meeting the requirements of high-end power equipment for high-performance silicon steel materials.

[0021] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing an oriented silicon steel coil with low iron loss and high magnetic induction intensity, characterized in that: Specifically, it includes the following steps: Step 1, Composition gradient design: Adopt a three-layer gradient composition structure, and the thickness ratios from the surface layer to the core of the steel coil are as follows: the thickness ratio of the surface layer is 20%, the thickness ratio of the intermediate layer is 60%, and the thickness ratio of the core is 20%; Step 2, Multi-stage rolling texture control: It includes billet pretreatment, hot rolling composite deformation, and cold rolling gradient deformation respectively; Step 3, Electromagnetic field-assisted annealing: First, perform primary annealing for texture activation. After the primary annealing is completed, perform decarburization annealing with precise atmosphere control. After the decarburization annealing is completed, finally perform high-temperature annealing with multi-field coupling regulation; Step 4, Surface treatment and post-processing: Use electrochemical etching to treat the steel coil after high-temperature annealing, and apply a double-layer insulating coating after treatment; Step 5, Precision shearing and finished product inspection: Precision shear the steel coil after surface treatment to obtain a finished product of grain-oriented silicon steel coil with low iron loss and high magnetic induction intensity that meets the specifications; Subsequently, conduct a comprehensive inspection of the finished product; Step 6, Environment-friendly cooling and packaging: After completing precision shearing and finished product inspection, use an environment-friendly coolant to quickly cool the steel coil; Subsequently, the steel coil is packaged in special moisture-proof and dust-proof packaging materials to ensure that the product remains in the best condition before reaching the end user.

2. A method for preparing an oriented silicon steel coil with low iron loss and high magnetic induction intensity according to claim 1, characterized in that: The chemical composition of the surface layer in Step 1 is by mass percentage: Si 3.3 - 3.5%, Mn 0.12 - 0.15%, Al 0.04 - 0.05%, Sn 0.02 - 0.03%, and the balance is Fe and unavoidable impurities; The chemical composition of the intermediate layer is by mass percentage: Si 3.0 - 3.2%, Mn 0.08 - 0.10%, Al 0.02 - 0.03%, Sn 0.01 - 0.02%, and the balance is Fe and unavoidable impurities; The chemical composition of the core is by mass percentage: Si 2.8 - 3.0%, Mn 0.05 - 0.07%, Al 0.01 - 0.02%, Sn 0.005 - 0.01%, and the balance is Fe and unavoidable impurities.

3. A method for preparing a grain-oriented silicon steel coil with low iron loss and high magnetic induction intensity according to claim 2, characterized in that: The chemical composition of the surface layer is preferably by mass percentage: Si 3.4%, Mn 0.13%, Al 0.05%, Sn 0.02%, and the balance is Fe and unavoidable impurities; The chemical composition of the intermediate layer is preferably by mass percentage: Si 3.1%, Mn 0.09%, Al 0.03%, Sn 0.01%, and the balance is Fe and unavoidable impurities; The chemical composition of the core is preferably by mass percentage: Si 2.9%, Mn 0.06%, Al 0.02%, Sn 0.001%, and the balance is Fe and unavoidable impurities.

4. A method for preparing a grain-oriented silicon steel coil with low iron loss and high magnetic induction intensity according to claim 2, characterized in that: The chemical composition of the surface layer is preferably by mass percentage: Si 3.5%, Mn 0.15%, Al 0.05%, Sn 0.03%, and the balance is Fe and unavoidable impurities; The chemical composition of the intermediate layer is preferably by mass percentage: Si 3.2%, Mn 0.10%, Al 0.03%, Sn 0.02%, and the balance is Fe and unavoidable impurities; The chemical composition of the core part is preferably by mass percentage: Si 3.0%, Mn 0.07%, Al 0.02%, Sn 0.01%, and the balance is Fe and inevitable impurities.

5. A method for preparing an oriented silicon steel coil with low iron loss and high magnetic induction intensity according to claim 1, characterized in that: In the second step, the billet pretreatment is specifically as follows: The electromagnetic stirring technology is adopted to eliminate composition segregation, and then ultrasonic flaw detection is carried out to detect internal defects. The electromagnetic stirring frequency is 50Hz, and the current intensity is 300A; then the billet is heated to 1320 - 1350°C and kept warm for 4 hours to promote the homogenization of alloy elements through high-temperature diffusion; The hot-rolled composite deformation specifically includes the following steps: The first stage of hot rolling: The rolling start temperature is 1280°C, asynchronous rolling is adopted, the upper and lower roll speed ratio is 1.15:1, the reduction ratio of the first two passes is 25% each, and shear deformation is introduced to promote the formation of γ fiber texture; The second stage of hot rolling: The final rolling temperature is 880 - 900°C, equal-diameter rolling is adopted, the reduction ratio of the last three passes decreases, 20% → 15% → 10%, and part of the unrecrystallized structure is retained to refine the grains; After hot rolling, water mist quenching is adopted, the water pressure is 5MPa, the water temperature is 20°C, and the cooling rate is controlled at 150°C / s to inhibit the precipitation of coarse carbides; The cold-rolled gradient deformation adopts a four-high reversible rolling mill and is cold-rolled in three stages, specifically including the following steps: The rough rolling stage: The reduction ratio is 70%, the rolling speed is 200m / min, and a strong α fiber texture is formed; The middle rolling stage: Intermediate annealing, after annealing to 750°C and keeping warm for 1 hour, the reduction ratio is 60%, the rolling speed is 150m / min, and plane strain compression is introduced; The finish rolling stage: The final rolling reduction ratio is 40%, the rolling speed is 100m / min, through roll profile optimization, the work roll convexity is 0.05mm, the sheet shape is controlled, and the final thickness is 0.23mm.

6. The preparation method of a grain-oriented silicon steel coil with low iron loss and high magnetic induction intensity according to claim 1, wherein: The primary annealing in the third step is specifically as follows: Heat to 850°C in an alternating magnetic field with a magnetic field strength of 0.5T and a frequency of 20kHz, and keep warm for 2 hours to promote the selective growth of favorable texture by the magnetostrictive effect; The decarburization annealing is specifically as follows: Adopt a wet hydrogen atmosphere, the H2O content is 3 - 5vol%, heat to 950°C at a rate of 5°C / min, and keep warm for 1.5 hours to reduce the carbon content to below 0.0015% through the hydrogen-oxygen reaction; The high-temperature annealing specifically is as follows: in an environment with a vacuum degree of 1×10 -3 Pa, a direct current magnetic field and an alternating current electric field are applied, heated to 1180°C at a rate of 3°C / min, held for 6 hours, the direct current magnetic field strength is 1.2 T, the alternating current electric field voltage is 50 V, and the frequency is 100 Hz; then enter the slow cooling stage, ultrasonic vibration is introduced in the slow cooling stage to promote the preferred growth of the Goss texture and inhibit the abnormal grain growth. The cooling rate in the slow cooling stage is 2°C / min, the power of the ultrasonic vibration is 2 kW, and the frequency is 20 kHz.

7. A method for preparing a grain-oriented silicon steel coil with low iron loss and high magnetic induction intensity according to claim 1, characterized in that: The electrochemical etching in the fourth step is specifically as follows: Adopt the electrochemical etching technology, the electrolyte is 10% HNO3 + 5% HF aqueous solution, and the etching depth is 5 - 8μm to remove the surface stress concentration area; Coating the double-layer insulating coating is specifically that the bottom layer is nano-SiO2 sol with a thickness of 1 - 2μm, and the surface layer is a phosphate coating with a thickness of 3 - 5μm to improve the corrosion resistance and insulation performance.

8. A method for preparing a grain-oriented silicon steel coil with low iron loss and high magnetic induction intensity according to claim 1, characterized in that: The fifth step includes but is not limited to magnetic property testing, iron loss testing, and microstructure analysis to ensure that each batch of finished products can meet the predetermined performance indicators; in addition, regular sampling and re-inspection of the finished products are carried out to continuously monitor the production quality, timely adjust the production process, and maintain the stability and consistency of product performance.

9. A method for preparing an oriented silicon steel coil with low iron loss and high magnetic induction intensity according to claim 1, characterized in that: On the packaging material in the sixth step, detailed product information and traceability codes are attached, which is convenient for users to understand the product performance and production batch, and enhances the traceability and transparency of the product.

Images