High-silicon steel thin strip and preparation method thereof

Abstract

The invention discloses a high-silicon steel thin strip and a preparation method thereof. The preparation method comprises the steps that raw materials are obtained; smelting the raw materials under the heating condition of 1450-1500 DEG C, and forging the raw materials into a forging stock with a first thickness under the heating condition of 900-1200 DEG C; heating the forging stock with the first thickness to 1050-1100 DEG C, preserving heat for a preset time, and then performing hot rolling to a second thickness; normalizing the hot-rolled forging stock at 800-850 DEG C, carrying out first annealing treatment on the normalized forging stock at 1100-1200 DEG C, carrying out acid pickling on the forging stock subjected to the first annealing treatment, and carrying out cold rolling on the forged stock subjected to the acid pickling to a third thickness; and the cold-rolled forging stock is subjected to secondary annealing treatment under the heating condition of 950-1050 DEG C, and the high-silicon steel thin strip is obtained. The plasticity, the strength and the magnetic performance of the high silicon steel can be improved.

Description

Technical Field

[0001] This application relates to the field of silicon steel strip preparation technology, specifically to a high-silicon steel thin strip and its preparation method. Background Technology

[0002] High-silicon steel, a key soft magnetic material in the power industry and electronics technology, is a silicon-iron soft magnetic alloy with extremely low carbon content (typically ≤0.08%). It is renowned for its unique soft magnetic properties, including low iron loss, high permeability, high resistivity, and near-zero magnetostriction coefficient. 6.0% Si high-silicon steel boasts a resistivity as high as 82 μΩ·cm, significantly reducing iron loss in high-frequency applications. Simultaneously, its near-zero magnetostriction coefficient greatly reduces noise in transformers and motors. While the high silicon content brings excellent magnetic properties, it also leads to a series of processing challenges, such as high room-temperature brittleness and hardness, making conventional cold working difficult.

[0003] Related technologies propose doping high-silicon steel with trace amounts of chromium or phosphorus. However, the method of doping with trace amounts of chromium results in inconsistent surface quality and thickness during production, and insufficient toughness. As for the method of doping with trace amounts of phosphorus, the strong solid solution strengthening effect and severe segregation tendency of phosphorus lead to fine cracks in the high-silicon steel after forming, thus affecting its mechanical and magnetic properties. Summary of the Invention

[0004] To address the aforementioned technical problems, this application proposes a high-silicon steel strip and its preparation method.

[0005] On one hand, embodiments of this application provide a method for preparing high-silicon steel strips, the method comprising: Obtain raw materials; the raw materials meet the following alloying element mass percentages: Co: 0.03%–0.15%, C: ≤0.003%, Si: 5.8%–6.15%, Mn: 0.05%–0.11%, S: ≤0.010%, N: 0.003%–0.007%, Al: 0.025%, with the remainder being Fe and impurity elements; The raw materials are melted under heating conditions of 1450℃-1500℃ and then forged into a forging blank of the first thickness under heating conditions of 900℃-1200℃. The forging billet of the first thickness is heated to 1050℃–1100℃, held at the temperature for a preset time, and then hot-rolled to the second thickness. The hot-rolled forging billet is normalized at 800℃–850℃, the normalized forging billet is annealed at 1100℃–1200℃, the forging billet after the first annealing is pickled, and the pickled forging billet is cold-rolled to the third thickness. The cold-rolled forging billet is subjected to a second annealing treatment at a heating temperature of 950℃–1050℃ to obtain high-silicon steel strip.

[0006] In an optional embodiment, the step of melting the raw material at a heating temperature of 1450℃-1500℃ and then forging it into a forging blank of a first thickness at a heating temperature of 900℃-1200℃ includes: The raw materials are mixed according to a preset ratio and then smelted by heating to 1450℃-1500℃ using a vacuum induction device. The forging blank of the first thickness is obtained by air free forging and multiple drawing under heating conditions of 900℃-1200℃.

[0007] In an optional embodiment, heating the forging billet of the first thickness to 1050℃-1100℃, holding it at that temperature for a preset time, and then hot-rolling it to the second thickness includes: The forging billet of the first thickness is heated to 1050℃–1100℃, and then held at the temperature for a preset time in a heating device at a temperature greater than or equal to 1000℃ before being hot rolled to the second thickness in multiple passes symmetrically. The second thickness is 2.0mm-2.5mm.

[0008] In an optional embodiment, the normalization process takes 1.0h-2.5h.

[0009] In an optional embodiment, the first annealing process takes 2-4 hours.

[0010] In an optional embodiment, the pickling solution is a dilute hydrochloric acid solution with a concentration of 0.1 mol / L to 0.5 mol / L.

[0011] In an optional embodiment, the second annealing treatment is performed under an argon protective atmosphere for 1-4 hours.

[0012] In an optional embodiment, the cold rolling is a multi-pass cold rolling, and the third thickness is 0.2mm-0.5mm.

[0013] In an optional embodiment, the high-silicon steel strip is a non-oriented high-silicon steel strip.

[0014] On the other hand, this application also provides a high-silicon steel strip, which is prepared by any of the above-described preparation methods, and the high-silicon steel strip comprises the following elements by mass percentage: Co: 0.03%–0.15%, C: ≤0.003%, Si: 5.8%–6.15%, Mn: 0.05%–0.11%, S: ≤0.010%, N: 0.003%–0.007%, Al: 0.025%, with the remainder being Fe and impurity elements.

[0015] Based on the above technical solution, the present invention has at least the following beneficial effects: This application provides a method for preparing high-silicon steel strips with trace amounts of Co. Under the same volume, cores made of Co-containing high-silicon steel can withstand stronger magnetic fields, significantly improving the power density and efficiency of electromagnetic devices. This is crucial for applications such as miniaturized and lightweight new energy vehicle drive motors and aerospace generators. Co, through solid solution strengthening and other mechanisms, can improve the creep resistance and overall mechanical strength of alloys at high temperatures. This allows components such as motor rotors made of Co-containing high-silicon steel to maintain better dimensional stability and mechanical integrity under harsh high-speed and high-temperature conditions. The addition of Co also enhances the material's hardness and wear resistance, which is beneficial for components with relative movement in motors (such as rotors with certain specific structures), helping to extend the equipment's service life.

[0016] Furthermore, this application optimizes the processing parameters (smelting raw materials at 1450℃-1500℃, forging to a first thickness billet at 900℃-1200℃, holding at 1050℃-1100℃ for a preset time followed by rolling, normalizing at 800℃-850℃, first annealing at 1100℃-1200℃, pickling the billet after the first annealing, cold rolling the pickled billet, and then heating the cold-rolled billet at 950℃-1050℃). The high-silicon steel strip is prepared by a second annealing process under heating conditions. This process synergistically regulates the microstructure and properties of the high-silicon steel strip. Compared with the defects such as cracks, unfavorable textures, increased brittleness, and reduced magnetic loss that occur during the cold rolling of traditional high-silicon steel, the high-silicon steel prepared by the method described in this application has fine grains, which can prevent element enrichment, reduce the formation of precipitates, and prevent a significant increase in harmful textures such as γ texture. This effectively enhances the plasticity of the high-silicon steel and simultaneously improves its strength and magnetic properties, thereby obtaining a high-silicon steel composition that is corrosion-resistant, easy to process, and has excellent magnetic properties. Attached Figure Description

[0017] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart illustrating an exemplary embodiment of the present application of a method for preparing a high-silicon steel strip. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of 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.

[0020] This application provides a method for preparing high-silicon steel strip. Figure 1 This is a schematic flowchart illustrating an exemplary embodiment of the present application of a method for preparing a high-silicon steel strip, as shown below. Figure 1 As shown, the method for preparing this high-silicon steel strip includes: Step S1. Obtain raw materials; the raw materials meet the following alloy element mass percentages: Co: 0.03%–0.15%, C: ≤0.003%, Si: 5.8%–6.15%, Mn: 0.05%–0.11%, S: ≤0.010%, N: 0.003%–0.007%, Al: 0.025%, with the remainder being Fe and impurity elements.

[0021] Optionally, the raw material may include industrial pure iron and high-purity silicon, as well as other major alloying elements, and the raw material meets the following alloying element mass percentages: Co: 0.03%–0.15%, C: ≤0.003%, Si: 5.8%–6.15%, Mn: 0.05%–0.11%, S: ≤0.010%, N: 0.003%–0.007%, Al: 0.025%, with the remainder being Fe and other avoided impurity elements.

[0022] Step S2. After melting the raw material under heating conditions of 1450℃-1500℃, forge it into a forging blank of the first thickness under heating conditions of 900℃-1200℃.

[0023] Optionally, during the smelting and forging process, the above raw materials can be fully mixed according to the above alloy element mass percentages, smelted under heating conditions of 1450℃-1500℃, and then forged into a forging blank of the first thickness under heating conditions of 900℃-1200℃.

[0024] In one specific embodiment, step S2 above may include: The raw materials are mixed according to a preset ratio and then smelted by heating to 1450℃-1500℃ using a vacuum induction device.

[0025] The forging blank of the first thickness is obtained by air free forging and multiple drawing under heating conditions of 900℃-1200℃.

[0026] In this embodiment, the raw materials can be mixed according to a preset composition ratio and then refined by heating to 1450℃-1500℃ using a vacuum induction device. Then, forging is carried out. During the forging process, the forging billet is heated to 900℃-1200℃ and the free forging equipment of the air hammer is used to gradually thin and lengthen the forging billet through multiple drawing operations, and finally make a forging billet with a thickness of the first thickness.

[0027] For example, the first thickness can be 20 mm, and the vacuum sensing device can be a vacuum induction furnace.

[0028] This application utilizes air-free forging, involving multiple drawing operations under heating conditions of 900℃-1200℃. This allows the metal material to remain in an austenitic state, achieving good plasticity and reducing deformation resistance. The upper limit of the forging temperature is 1200℃, close to the initial forging temperature of steel, avoiding overheating (coarse grains) or burning (grain boundary melting). The lower limit is 900℃, higher than the final forging temperature of steel, ensuring sufficient plasticity is maintained during deformation and preventing cold brittle cracking. Furthermore, since a single large deformation can easily lead to internal stress concentration or cracking, this application employs multiple drawing operations to ensure uniform deformation on all surfaces. Thus, through hot plastic deformation, the internal structure of the metal can be improved (refining grains, eliminating forging defects), while obtaining a forging blank of the required size as raw material for subsequent processing, thereby achieving control over dimensions and properties.

[0029] Step S3. Heat the forging billet of the first thickness to 1050℃–1100℃, hold it at that temperature for a preset time, and then hot roll it to the second thickness.

[0030] Optionally, after forging, a hot rolling operation can be performed. During the hot rolling operation, the forging billet of the first thickness can be heated to 1050℃–1100℃, held at the temperature for a preset time, and then hot rolled to the second thickness.

[0031] In an exemplary embodiment, step S3 above may include: The forging billet of the first thickness is heated to 1050℃–1100℃, and then held at the temperature for a preset time in a heating device at a temperature greater than or equal to 1000℃ before being rolled to the second thickness in multiple passes symmetrically.

[0032] In this embodiment, the forging billet of the first thickness can be heated to 1050℃–1100℃, held at a temperature not lower than 1000℃ (i.e., greater than or equal to 1000℃) for a preset time, and then symmetrically rolled in multiple passes to the second thickness. For example, the second thickness can be 2.0mm–2.5mm, and the preset time can be 1h–3h, for example, 2h. The heating equipment can be a heating furnace.

[0033] Therefore, rolling at 1050℃–1100℃ ensures that the forging billet is in a uniform single-phase austenitic state. The single-phase microstructure exhibits good plasticity, relatively low and uniform deformation resistance, which is beneficial for stable rolling and obtaining a uniform internal strain distribution. This provides a better and more uniform deformation for subsequent cold rolling. Furthermore, it allows for control of precipitates to achieve a uniform and appropriate grain size during final annealing. In addition, hot rolling the forging billet to a thickness of 2.0mm–2.5mm provides an optimal starting point for the subsequent complex cold rolling and annealing process chain, a necessary condition for forming a strong deformation texture. During subsequent annealing, this strong deformation texture forms the basis for developing an ideal recrystallization texture. This thickness also ensures that the hot-rolled plate obtains uniform and fine ferrite grains after coiling and cooling.

[0034] Step S4. Normalize the hot-rolled forging billet at 800℃–850℃, anneal the normalized forging billet at 1100℃–1200℃, pickle the forging billet after the first annealing, and cold roll the pickled forging billet to the third thickness.

[0035] In some embodiments, the normalization process can be performed at a medium temperature of 800°C–850°C. Optionally, the normalization time can be 1.0 h–2.5 h.

[0036] The temperature range of 800℃–850℃ ensures sufficient austenitization or phase transformation for a homogeneous microstructure and is also the critical temperature window for inhibitor precipitation, ensuring that the inhibitor precipitates in a favorable morphology. The treatment time of 1.0h–2.5h allows for temperature uniformity in the prepared high-silicon rigid cross-section, completes the austenitization or microstructure homogenization process, and ensures sufficient inhibitor precipitation to achieve the desired size and distribution (too short a time results in insufficient precipitation; too long a time leads to coarsening of the inhibitor particles and weakened inhibitory effect). In summary, normalization at 800℃–850℃ for 1.0h–2.5h promotes texture and microstructure regulation, leading to a fully recrystallized microstructure.

[0037] In some embodiments, for the first annealing step, the normalized forging billet can be subjected to a first homogenization annealing treatment at 1100℃–1200℃. Optionally, the duration of this first homogenization annealing treatment can be 2h–4h.

[0038] On the one hand, at 1100℃–1200℃, the diffusion rate of substitutional solute atoms such as silicon and aluminum is several orders of magnitude higher than at lower temperatures. Prolonged holding time (2h–4h) provides ample time for long-range atomic diffusion, thus reducing microsegregation. On the other hand, the interdendritic solute-rich regions present in the hot-rolled forgings undergo solute migration from high-concentration areas to low-concentration areas during high-temperature, long-term annealing via bulk diffusion and grain boundary diffusion, leading to overall compositional equilibrium and eliminating solidification segregation. Furthermore, high-temperature annealing results in complete recrystallization, forming new equiaxed grains accompanied by grain boundary migration. While grain boundary migration may redistribute solutes in the "sweeped" areas, the prolonged high temperature ultimately makes the solutes more homogeneous within the grains. Grain growth reduces the total grain boundary area, facilitating the resolution or homogenization of some solutes segregated at the grain boundaries. On the other hand, at lower temperatures, ordered structures may exist, which may "pin" the solute. Above approximately 1100℃, the solute is usually in a disordered solid solution state, allowing for freer atomic migration, which is beneficial for composition homogenization. Homogenization annealing at 1100℃–1200℃ for 2-4 hours can improve composition homogenization. After homogenization, magnetic properties become more uniform (increased permeability, reduced iron loss), and mechanical properties become more consistent, thus providing a better foundation for subsequent cold rolling.

[0039] In some embodiments, dilute hydrochloric acid solution, sulfuric acid solution, mixed acid solution, etc., can be used for the pickling process. The mixed acid solution can be a mixture of hydrochloric acid solution and hydrofluoric acid solution, or a mixture of sulfuric acid solution and hydrofluoric acid solution. Taking dilute hydrochloric acid solution as an example, the concentration of the dilute hydrochloric acid solution is 0.1 mol / L-0.5 mol / L.

[0040] After the initial degradation treatment, a thin oxide film typically forms on the surface of high-silicon steel. High-concentration pickling rapidly and violently attacks this film and the substrate, leading to over-corrosion. In contrast, dilute hydrochloric acid (0.1 L / L - 0.5 mol / L) can slowly and uniformly dissolve this film, achieving precise removal and exposing a clean metal substrate. Furthermore, high-concentration acid preferentially attacks grain boundaries and defects, resulting in surface roughness and even pitting. Low-concentration pickling, through a gentle reaction, can remove the oxide film while preserving the original smoothness of the substrate to the greatest extent possible, thus reducing iron loss. During pickling, high-concentration pickling hydrogen atoms penetrate into the steel, accumulating at grain boundaries and other defects, causing material embrittlement. Dilute hydrochloric acid reacts more slowly, producing less hydrogen and having a lower penetration driving force, thus avoiding hydrogen embrittlement. In addition, the core value of high silicon steel lies in its excellent soft magnetic properties of high resistivity and low iron loss. Violent pickling can destroy the integrity of the surface lattice, introduce stress, and even change the surface texture, which may have an adverse effect on the magnetic properties. The gentle process of dilute pickling can better protect the favorable texture and internal stress state formed after annealing.

[0041] In some embodiments, for the room temperature cold rolling step, the pickled forging billet can be cold rolled to a third thickness through multiple passes of decreasing deformation at room temperature. Optionally, the third thickness is 0.2mm-0.5mm, and the total deformation rate is over 80%.

[0042] This application's embodiment employs multi-pass cold rolling with decreasing deformation to achieve a thickness of 0.2mm-0.5mm, which offers the following advantages: 1) Refining grains and homogenizing the microstructure: Gradual strain accumulation promotes grain refinement, resulting in a more uniform microstructure. Large deformation (>80%) introduces high-density dislocations, providing sufficient driving force for subsequent recrystallization annealing, which is beneficial for obtaining fine and uniform recrystallized grains, thereby improving magnetic properties (reducing iron loss); 2) Improving texture and optimizing magnetic properties: Non-oriented silicon steel aims to obtain as many favorable textures as possible to improve magnetic permeability and reduce iron loss. Multi-pass cold rolling combined with large deformation allows for adjustment of the type and intensity of deformation texture. By rationally allocating passes (decreasing deformation), the grain rotation path can be controlled, which is beneficial for forming a recrystallization texture that is conducive to magnetism after recrystallization annealing; 3) Improving the shape accuracy and thickness uniformity of silicon steel sheets: Multi-pass, decreasing deformation makes the rolling process more stable, reducing thickness fluctuations and poor sheet shape (such as edge cracks and warping). High-silicon steel is brittle and prone to cracking if the deformation in a single pass is too large. Multi-pass decreasing deformation can disperse deformation stress and reduce cracking tendency; 4) Promotes the distribution of beneficial precipitates: Large deformation cold rolling can make precipitates smaller and more dispersed, which helps to suppress abnormal grain growth during annealing, obtain uniform grain size, and thus reduce iron loss; 5) Facilitates recrystallization and grain growth in subsequent annealing processes: Large cold rolling deformation with a total deformation of >80% stores a high amount of deformation energy, providing a strong driving force for recrystallization. The recrystallization temperature can be appropriately reduced, the recrystallization process is more complete, which is conducive to the formation of a uniform equiaxed grain structure and improves the uniformity of magnetic properties; 6) Improves the magnetic induction of the final product and reduces iron loss: Increases magnetic induction intensity, significantly reduces iron loss, increases magnetic permeability, and reduces excitation power. Experiments have shown that the fracture probability decreases by 80% during cold rolling, the average grain size is between 15 micrometers and 30 micrometers, the tensile strength is ≥450MPa, and the elongation is ≥15%.

[0043] Step S5. The cold-rolled forging billet is subjected to a second annealing treatment under heating conditions of 950℃–1050℃ to obtain high silicon steel strip.

[0044] In this embodiment of the application, after cold rolling, a second annealing treatment can be performed under heating conditions of 950℃–1050℃ to eliminate residual stress and complete the recrystallization process, thereby obtaining high silicon steel strip.

[0045] Optionally, the second degradation process can be carried out under an argon protective atmosphere, and the second annealing process takes 1-4 hours.

[0046] Alternatively, the high-silicon steel strip can be a non-oriented high-silicon steel strip.

[0047] In this embodiment, the lower limit of the temperature for the second degradation treatment is set at 950°C to ensure that the temperature is high enough to allow the entire cross-section to quickly and uniformly reach above the recrystallization temperature, avoiding incomplete recrystallization and incomplete elimination of internal stress due to insufficient temperature. The lower limit of the temperature is set at 1050°C to prevent excessively high temperatures, which may lead to the following defects: abnormally coarse grains, damaging the mechanical properties and surface quality of the material; excessive precipitation or increased ordering of silicon-rich phases, potentially increasing brittleness; increased oxidation risk; and increased energy consumption. The lower limit of the annealing time is set at 1 hour, which is sufficient to ensure heat penetration and completion of the recrystallization process for thinner forgings. The upper limit of the time is set at 4 hours, providing a longer holding time for thicker billets or when a more uniform grain growth and more stable ordered structure are desired. The use of an argon protective atmosphere effectively isolates oxygen, preventing silicon and iron from being oxidized on the surface to form an oxide layer, thereby ensuring a bright surface, stable composition, and excellent magnetic properties for the forging. In summary, annealing cold-rolled forgings at 950℃–1050℃ under an argon protective atmosphere for 1-4 hours achieves the following beneficial effects: it efficiently eliminates residual stress from cold rolling; it completes sufficient recrystallization, forming a uniform equiaxed crystal structure; it lays the microstructural foundation for obtaining optimal magnetic properties with low iron loss and high permeability; it restores the plasticity of the material, facilitating subsequent processing; and under argon protection, it avoids high-temperature oxidation, ensuring the purity and surface quality of the material.

[0048] Therefore, this application optimizes the processing parameters (smelting raw materials at 1450℃-1500℃, forging to a first thickness billet at 900℃-1200℃, holding at 1050℃-1100℃ for a preset time followed by rolling, normalizing at 800℃-850℃, first annealing at 1100℃-1200℃, pickling the billet after the first annealing, cold rolling the pickled billet, and then heating the cold-rolled billet at 950℃-1050℃). The high-silicon steel strip is prepared by a second annealing process under heating conditions. This process synergistically regulates the microstructure and properties of the high-silicon steel strip. Compared with the defects such as cracks, unfavorable textures, increased brittleness, and reduced magnetic loss that occur during the cold rolling of traditional high-silicon steel, the high-silicon steel prepared by the method described in this application has fine grains, which can prevent element enrichment, reduce the formation of precipitates, and prevent a significant increase in harmful textures such as γ texture. This effectively enhances the plasticity of the high-silicon steel and simultaneously improves its strength and magnetic properties, thereby obtaining a high-silicon steel composition that is corrosion-resistant, easy to process, and has excellent magnetic properties.

[0049] This application embodiment also provides a high-silicon steel strip, which comprises the following elements by mass percentage: Co: 0.03%–0.15%, C: ≤0.003%, Si: 5.8%–6.15%, Mn: 0.05%–0.11%, S: ≤0.010%, N: 0.003%–0.007%, Al: 0.025%, with the remainder being Fe and impurity elements.

[0050] Within the same volume, cores made of Co-containing high-silicon steel can withstand stronger magnetic fields, significantly improving the power density and efficiency of electromagnetic devices. This is crucial for applications such as miniaturized and lightweight new energy vehicle drive motors and aerospace generators. Co, through mechanisms like solid solution strengthening, enhances the alloy's creep resistance and overall mechanical strength at high temperatures. This allows components like motor rotors made of Co-containing high-silicon steel to maintain better dimensional stability and mechanical integrity under harsh high-speed and high-temperature conditions. The addition of Co also enhances the material's hardness and wear resistance, which is highly beneficial for components with relative movement in motors (such as rotors with certain structures), helping to extend the equipment's lifespan.

[0051] Table 1 compares the performance of the Co-containing high-silicon steel prepared in the embodiments of this application with that of Al-containing high-silicon steel and Mn-containing high-silicon steel in related technologies. As shown in Table 1, the Co-containing high-silicon steel prepared in the embodiments of this application has lower density, lower grain boundary inclusion content, lower coercivity, lower iron loss, moderate surface corrosion-resistant area, and higher bending strength. It is evident that the Co-containing high-silicon steel prepared in the embodiments of this application can effectively enhance plasticity, while simultaneously improving strength and magnetic properties, and also exhibits good corrosion resistance.

[0052] Table 1. Performance Comparison of Co-containing High-Silicon Steel Prepared in the Examples of this Application with Al-containing High-Silicon Steel and Mn-containing High-Silicon Steel in Related Technologies. In some embodiments, the test methods and conditions for the above performance can be as shown in Table 2.

[0053] Table 2 Test methods and conditions for various performance characteristics This application also provides a series of embodiments to further verify the implementation effect of the high-silicon steel strip and its preparation method in this application. The implementation effect of the technical solution of this application is described in detail below with reference to specific embodiments.

[0054] Example 1: This application provides a high-silicon steel strip, which comprises the following elements by mass percentage: Co: 0.03%, C: 0.001%, Si: 5.8%, Mn: 0.05%, S: 0%, N: 0.003%, Al: 0.025%, with the remainder being Fe and impurity elements.

[0055] The preparation method of this high-silicon steel strip includes: 1. Obtaining raw materials: The raw materials meet the following alloying element mass percentages: Co: 0.03%, C: 0.001%, Si: 5.8%, Mn: 0.05%, S: 0%, N: 0.003%, Al: 0.025%, with the remainder being Fe and impurity elements.

[0056] 2. Melting: The raw materials are fully mixed according to a certain composition ratio and then refined by heating in a vacuum induction furnace to 1450°C.

[0057] 3. Forging: The billet is forged into a first thickness (20mm) by air free forging and multiple drawing under heating conditions of 900℃.

[0058] 4. Hot rolling: The forging billet of the first thickness is heated to 1050°C and held in a heating furnace at a temperature of not less than 1000°C for 2 hours. Then, it is rolled symmetrically in multiple passes to a second thickness of 2.0 mm.

[0059] 5. Normalizing treatment: The hot-rolled forging billet is normalized at a medium temperature (800℃, 1.0h) to promote texture and microstructure control so that it forms a fully recrystallized microstructure.

[0060] 6. Homogenization annealing: The normalized forging billet is annealed at 1100℃ for 2 hours to improve the uniformity of composition.

[0061] 7. Pickling: Use dilute hydrochloric acid solution (0.1 mol / L) as the pickling solution.

[0062] 8. Room temperature cold rolling: The pickled forging billet is cold rolled to a third thickness of 0.2mm, using multi-pass decreasing deformation, with a total deformation rate of over 80%.

[0063] 9. Final annealing: The cold-rolled forging billet is annealed at 950℃ under an argon protective atmosphere for 1 hour to eliminate residual stress and complete the recrystallization process, thus obtaining high-silicon steel strip.

[0064] The high-silicon steel strip prepared in this example has a density of 99.2, an average grain size of 7.7 μm, a grain boundary inclusion content of 750 ppm, a coercivity of 950 (A / M), an iron loss of 6.8P15 / 50, a surface corrosion-resistant area of ​​67%, and a bending strength of 360 MPa.

[0065] Example 2: This application provides a high-silicon steel strip, which comprises the following elements by mass percentage: Co: 0.08%, C: 0.002%, Si: 5.95%, Mn: 0.07%, S: 0.005%, N: 0.005%, Al: 0.025%, with the remainder being Fe and impurity elements.

[0066] The preparation method of this high-silicon steel strip includes: 1. Obtaining raw materials: The raw materials meet the following alloying element mass percentages: Co: 0.08%, C: 0.002%, Si: 5.95%, Mn: 0.07%, S: 0.005%, N: 0.005%, Al: 0.025%, with the remainder being Fe and impurity elements.

[0067] 2. Smelting: The raw materials are fully mixed according to a certain composition ratio and then refined by heating in a vacuum induction furnace to 1460°C.

[0068] 3. Forging: The billet is forged into a first thickness (20mm) by air free forging and multiple drawing under heating conditions of 1000℃.

[0069] 4. Hot rolling: The forging billet of the first thickness is heated to 1060°C and held in a heating furnace at a temperature of not less than 1000°C for 2 hours. Then, it is rolled symmetrically in multiple passes to a second thickness of 2.1 mm.

[0070] 5. Normalizing treatment: The hot-rolled forging billet is normalized at a medium temperature (820℃, 1.5h) to promote texture and microstructure control so that it forms a fully recrystallized microstructure.

[0071] 6. Homogenization annealing: The normalized forging billet is annealed at 1120℃ for 2 hours to improve the uniformity of composition.

[0072] 7. Pickling: Use dilute hydrochloric acid solution (0.2 mol / L) as the pickling solution.

[0073] 8. Room temperature cold rolling: The pickled forging billet is cold rolled to a third thickness of 0.3mm, using multi-pass decreasing deformation, with a total deformation rate of over 80%.

[0074] 9. Final annealing: The cold-rolled forging billet is annealed at 970℃ under an argon protective atmosphere for 2 hours to eliminate residual stress and complete the recrystallization process, resulting in high-silicon steel strip.

[0075] The high-silicon steel strip prepared in this example has a density of 99.4, an average grain size of 7.5 μm, a grain boundary inclusion content of 740 ppm, a coercivity of 930 (A / M), an iron loss of 6.7P15 / 50, a surface corrosion-resistant area of ​​65%, and a bending strength of 362 MPa.

[0076] Example 3: This application provides a high-silicon steel strip, which comprises the following elements by mass percentage: Co: 0.10%, C: 0.002%, Si: 6.05%, Mn: 0.08%, S: 0.008%, N: 0.006%, Al: 0.025%, with the remainder being Fe and impurity elements.

[0077] The preparation method of this high-silicon steel strip includes: 1. Obtaining raw materials: The raw materials meet the following alloy element mass percentages: Co: 0.10%, C: 0.002%, Si: 6.05%, Mn: 0.08%, S: 0.008%, N: 0.006%, Al: 0.025%, with the remainder being Fe and impurity elements.

[0078] 2. Smelting: The raw materials are fully mixed according to a certain composition ratio and then refined by heating in a vacuum induction furnace to 1470°C.

[0079] 3. Forging: The billet is forged into a first thickness (20mm) by air free forging and multiple drawing under heating conditions of 1150℃.

[0080] 4. Hot rolling: The forging billet of the first thickness is heated to 1080°C and held in a heating furnace at a temperature of not less than 1000°C for 2 hours. Then, it is rolled symmetrically in multiple passes to a second thickness of 2.3 mm.

[0081] 5. Normalizing treatment: The hot-rolled forging billet is normalized at medium temperature (830℃, 2h) to promote texture and microstructure control so that it forms a fully recrystallized microstructure.

[0082] 6. Homogenization annealing: The normalized forging billet is annealed at 1150℃ for 3 hours to improve the uniformity of composition.

[0083] 7. Pickling: Use dilute hydrochloric acid solution (0.3 mol / L) as the pickling solution.

[0084] 8. Room temperature cold rolling: The pickled forging billet is cold rolled to a third thickness of 0.4 mm, using multi-pass decreasing deformation, with a total deformation rate of over 80%.

[0085] 9. Final annealing: The cold-rolled forging billet is annealed at 980℃ under an argon protective atmosphere for 3 hours to eliminate residual stress and complete the recrystallization process, resulting in high-silicon steel strip.

[0086] The high-silicon steel strip prepared in this example has a density of 99.6, an average grain size of 7.3 μm, a grain boundary inclusion content of 720 ppm, a coercivity of 920 (A / M), an iron loss of 6.5P15 / 50, a surface corrosion-resistant area of ​​63%, and a bending strength of 365 MPa.

[0087] Example 4: This application provides a high-silicon steel strip, which comprises the following elements by mass percentage: Co: 0.15%, C: 0.003%, Si: 6.15%, Mn: 0.11%, S: 0.01%, N: 0.007%, Al: 0.025%, with the remainder being Fe and impurity elements.

[0088] The preparation method of this high-silicon steel strip includes: 1. Obtaining raw materials: The raw materials meet the following alloy element mass percentages: Co: 0.15%, C: 0.003%, Si: 6.15%, Mn: 0.11%, S: 0.01%, N: 0.007%, Al: 0.025%, with the remainder being Fe and impurity elements.

[0089] 2. Melting: The raw materials are fully mixed according to a certain composition ratio and then refined by heating in a vacuum induction furnace to 1500°C.

[0090] 3. Forging: The billet is forged into a first thickness (20mm) by air free forging and multiple drawing under heating conditions of 1200℃.

[0091] 4. Hot rolling: The forging billet of the first thickness is heated to 1100℃, and after being held in a heating furnace at a temperature of not less than 1000℃ for 2 hours, it is rolled symmetrically in multiple passes to a second thickness of 2.5mm.

[0092] 5. Normalizing treatment: The hot-rolled forging billet is normalized at a medium temperature (850℃, 2.5h) to promote texture and microstructure control so that it forms a fully recrystallized microstructure.

[0093] 6. Homogenization annealing: The normalized forging billet is annealed at 1200℃ for 4 hours to improve the uniformity of composition.

[0094] 7. Pickling: Use dilute hydrochloric acid solution (0.5 mol / L) as the pickling solution.

[0095] 8. Room temperature cold rolling: The pickled forging billet is cold rolled to a third thickness of 0.5mm, using multi-pass decreasing deformation, with a total deformation rate of over 80%.

[0096] 9. Final annealing: The cold-rolled forging billet is annealed at 1050℃ under an argon protective atmosphere for 4 hours to eliminate residual stress and complete the recrystallization process, resulting in high-silicon steel strip.

[0097] The high-silicon steel strip prepared in this example has a density of 99.3, an average grain size of 7.0 μm, a grain boundary inclusion content of 740 ppm, a coercivity of 930 (A / M), an iron loss of 6.8P15 / 50, a surface corrosion-resistant area of ​​65%, and a bending strength of 362 MPa.

[0098] Comparative Example 1: Compared to Example 3, Comparative Example 1 had Co = 0.25% (>0.15%; content too high), but otherwise remained the same as Example 3, except for a corresponding reduction in Fe.

[0099] Experiments showed that the coercivity of the high-silicon steel strip prepared in this embodiment was significantly improved compared to that in Example 3, while the iron loss was significantly reduced. This demonstrates that excessively high Co content deteriorates the soft magnetic properties of the material, particularly leading to increased coercivity, decreased permeability, increased losses, and the destruction of its low magnetostriction characteristics.

[0100] Comparative Example 2: In Comparative Example 2, Co = 0.02% (<0.03%; content too low) was used, while in Example 3, all other aspects were the same.

[0101] Experiments showed that the coercivity of the high-silicon steel strip prepared in this example was slightly improved compared to Example 3, while the iron loss was slightly reduced. This indicates that excessively low Co content has a slight impact on soft magnetic properties.

[0102] Comparative Example 3: In Comparative Example 3, Si = 6.50% (>6.15%; content is too high) was used, while other aspects were the same as in Example 3.

[0103] Experiments showed that Si atoms can induce lattice distortion through atomic solid solution, significantly enhancing the scattering of free electrons. Furthermore, Si atoms reduce the magnetocrystalline anisotropy of ferromagnets, and as a non-magnetic element, their addition dilutes the concentration of ferromagnetic atoms. The addition of Si also significantly alters the magnetostriction coefficient. Therefore, the high-silicon steel strip prepared in this embodiment exhibits slightly lower iron loss and better magnetic properties compared to Example 3. However, the higher Si content results in poorer processing performance, deteriorating the material's room-temperature plasticity and ductility, making it difficult to obtain a strong texture compared to Example 3.

[0104] Comparative Example 4: Comparative Example 4 was the same as Example 3 except that Mn = 0.15% (>0.11%; the content was too high).

[0105] Experiments have shown that Mn is a strong austenite stabilizing element. During the heating and annealing process of silicon steel, the addition of Mn expands the γ phase (austenite) region and lowers the α→γ phase transformation temperature, thereby complicating the high-temperature phase transformation and hindering the normal growth of recrystallized grains. This may result in uneven grain size after final annealing, with abnormally large grains appearing instead of the ideal uniform large grains compared to Example 3, leading to a deterioration of the microstructure.

[0106] Regarding magnetic properties, although abnormally large grains reduce the total area of ​​grain boundaries, they can lead to an increase in magnetic domain width, an increase in abnormal eddy current loss (the volume swept by the domain wall when it moves is larger, and the local eddy current loss induced at the domain wall increases significantly), and an increase in hysteresis loss (excessively large grains may reduce the number of domain wall pinning points, but the pinning force changes in a complex way, and the initial magnetic susceptibility may decrease), thereby significantly increasing the coercivity.

[0107] As can be seen, compared with Example 3, Comparative Example 4 significantly increases coercivity, hysteresis loss and abnormal loss, worsens total iron loss, and decreases magnetic permeability in terms of magnetic properties. Regarding stability, Comparative Example 4 exhibits decreased microstructural stability and reduced long-term performance reliability.

[0108] Table 3 is a comparison table of elemental contents for each embodiment and comparative example. As shown in Table 3 and the above analysis, compared with Example 3 and Comparative Example 1, excessive Co content will deteriorate the soft magnetic properties of the material, especially leading to increased coercivity, decreased permeability, increased loss, and damage to its low magnetostriction characteristics.

[0109] Compared with Example 3 and Comparative Example 2, a low Co content has a slight impact on soft magnetic properties. Compared with Example 3 and Comparative Example 3, a higher Si content slightly reduces iron loss and achieves better magnetic properties. However, the higher Si content leads to poorer processing performance, deteriorates the material's room temperature plasticity and ductility, and makes it difficult to obtain a strong texture.

[0110] For Examples 3 and 4, regarding magnetic properties, excessively high Mn content significantly increases coercivity, hysteresis loss and abnormal loss, worsens total iron loss, and decreases permeability. Regarding stability, excessively high Mn content reduces microstructural stability and reliability.

[0111] Table 3. Comparison of elemental contents in various embodiments and comparative examples. It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, specific embodiments have been described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in a different order than that shown in the embodiments and still achieve the desired result. Additionally, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0112] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0113] It should be noted that all features described in this invention (including technical features described in different embodiments) can be combined arbitrarily under reasonable circumstances, and the new technical solutions formed by such combinations are all within the protection scope of this invention. The above description is only some embodiments of this invention and is not intended to limit this invention. Those skilled in the art should understand that this invention can have various changes and improvements, and any modifications, equivalent substitutions, and improvements made in accordance with this invention fall within the protection scope claimed by this invention.

Claims

1. A method for preparing high-silicon steel strip, characterized in that, The preparation method includes: Obtain raw materials; the raw materials meet the following alloying element mass percentages: Co: 0.03%–0.15%, C: ≤0.003%, Si: 5.8%–6.15%, Mn: 0.05%–0.11%, S: ≤0.010%, N: 0.003%–0.007%, Al: 0.025%, with the remainder being Fe and impurity elements; The raw materials are melted under heating conditions of 1450℃-1500℃ and then forged into a forging blank of the first thickness under heating conditions of 900℃-1200℃. The forging billet of the first thickness is heated to 1050℃–1100℃, held at the temperature for a preset time, and then hot-rolled to the second thickness. The hot-rolled forging billet is normalized at 800℃–850℃, the normalized forging billet is annealed at 1100℃–1200℃, the forging billet after the first annealing is pickled, and the pickled forging billet is cold-rolled to the third thickness. The cold-rolled forging billet is subjected to a second annealing treatment at a heating temperature of 950℃–1050℃ to obtain high-silicon steel strip.

2. The preparation method according to claim 1, characterized in that, The process of melting the raw material at a heating temperature of 1450℃-1500℃ and then forging it into a forging blank of a first thickness at a heating temperature of 900℃-1200℃ includes: The raw materials are mixed according to a preset ratio and then smelted by heating to 1450℃-1500℃ using a vacuum induction device. The forging blank of the first thickness is obtained by air free forging and multiple drawing under heating conditions of 900℃-1200℃.

3. The preparation method according to claim 1, characterized in that, The step of heating the forging billet of the first thickness to 1050℃-1100℃, holding it at that temperature for a preset time, and then hot-rolling it to the second thickness includes: The forging billet of the first thickness is heated to 1050℃–1100℃, and then held at the temperature for a preset time in a heating device at a temperature greater than or equal to 1000℃ before being hot rolled to the second thickness in multiple passes symmetrically. The second thickness is 2.0mm-2.5mm.

4. The preparation method according to claim 1, characterized in that, The normalization process takes 1.0h to 2.5h.

5. The preparation method according to claim 1, characterized in that, The first annealing process takes 2-4 hours.

6. The preparation method according to claim 1, characterized in that, The pickling solution is a dilute hydrochloric acid solution with a concentration of 0.1 mol / L to 0.5 mol / L.

7. The preparation method according to claim 1, characterized in that, The second annealing process is carried out under an argon protective atmosphere, and the duration of the second annealing process is 1-4 hours.

8. The preparation method according to claim 1, characterized in that, The cold rolling is a multi-pass cold rolling, and the third thickness is 0.2mm-0.5mm.

9. The preparation method according to any one of claims 1 to 8, characterized in that, The high-silicon steel strip is a non-oriented high-silicon steel strip.

10. A high-silicon steel strip, characterized in that, The high-silicon steel strip is prepared by the preparation method according to any one of claims 1 to 9, and the high-silicon steel strip comprises the following elements by mass percentage: Co: 0.03%–0.15%, C: ≤0.003%, Si: 5.8%–6.15%, Mn: 0.05%–0.11%, S: ≤0.010%, N: 0.003%–0.007%, Al: 0.025%, with the remainder being Fe and impurity elements.

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