High-silicon steel thin strip containing trace antimony and preparation method of high-silicon steel thin strip

Abstract

The invention discloses a trace antimony-containing high-silicon steel thin strip and a preparation method thereof, and belongs to the field of high-performance soft magnetic materials and advanced manufacturing processes thereof. The high-silicon steel thin strip containing trace antimony comprises the following chemical components in percentage by mass: 4.5-7.0% of Si, 0.01-0.50% of Sb, less than or equal to 0.002% of C, less than or equal to 0.002% of N, less than or equal to 0.002% of O, less than or equal to 0.002% of S and the balance of Fe and inevitable impurities. The preparation method comprises the following steps: smelting according to design components; a thin strip with the thickness ranging from 0.03 mm to 0.15 mm is prepared through a plane flow casting technology; and carrying out low-strain leveling rolling with the total rolling reduction of less than or equal to 30%, and carrying out annealing treatment. The method has the advantages that the finally obtained high-silicon steel thin strip is uniform in thickness, excellent in surface quality and outstanding in magnetic performance.

Description

Technical Field

[0001] The present invention belongs to the field of high-performance soft magnetic materials and their advanced manufacturing processes, and particularly relates to a high-silicon steel strip containing trace antimony and a planar flow casting preparation method thereof. Background Art

[0002] Non-oriented silicon steel is widely used in the core manufacturing of industrial motors, transformers, household appliances and other equipment. With the rapid development of new energy vehicles, power electronics, renewable energy and other fields, the demand for high-efficiency and low-loss soft magnetic materials is increasing day by day, and non-oriented silicon steel has become a key functional material in the power regulation, transmission and conversion links.

[0003] High-silicon steel generally refers to silicon steel with a silicon content exceeding 4.5 wt.%, especially silicon steel with a silicon content of 6.5 wt.%. It has excellent soft magnetic properties, showing high magnetic permeability, high magnetic flux density, high resistivity, low iron loss at high frequencies and nearly zero magnetostrictive effect, and is one of the most promising soft magnetic materials. Compared with traditional 3.0 wt.% Si non-oriented silicon steel, the high resistivity of high-silicon steel can effectively suppress eddy current loss under high-frequency conditions, showing lower iron loss and better energy efficiency performance.

[0004] Although high-silicon steel has excellent soft magnetic properties, with the increase of Si content, stable ordered structures such as B2 and D03 are easily formed between Si and Fe atoms, significantly increasing the brittleness of the material, severely weakening its room-temperature plasticity, and making it unable to adapt to conventional plastic processing processes such as hot rolling and cold rolling, which has become the core technical obstacle restricting its industrialization. At present, only JFE Company in Japan has realized the industrial production of 6.5 wt.% Si high-silicon steel by chemical vapor deposition (CVD) technology globally, but this process has problems such as complex equipment, high energy consumption and serious pollution, which limits the feasibility and economy of its popularization and application.

[0005] Aiming at the problems of increased brittleness and processing difficulties caused by the formation of ordered phases in high-silicon steel, alloying is regarded as an effective strategy to improve its organizational structure and processing performance. By introducing alloying elements such as Cu, Cr, Nb, Ni, etc., the grains can be effectively refined, the matrix structure can be strengthened, and the formation of ordered phases can be inhibited to a certain extent, thereby improving the plasticity and ductility of high-silicon steel. In addition, rare earth elements such as Ce, La, Y have significant effects on steel liquid purification, inclusion modification and grain refinement, further optimizing the recrystallization texture, promoting the formation of favorable textures, and enhancing the antioxidant ability. Although alloying has achieved certain results in alleviating brittleness and improving processing performance, it has not fundamentally solved the core problem of poor room-temperature plasticity, and some alloying elements may introduce second phases, affecting magnetic properties, and it is difficult to achieve a comprehensive balance between performance and processability. Therefore, relying solely on the alloying strategy is difficult to break through the core bottleneck of high-silicon steel preparation, and it is necessary to seek a breakthrough in the process to fundamentally solve the problem of coordinating forming and performance.

[0006] In recent years, with the continuous development of rapid solidification and near-net forming technology, the plane flow casting process is considered to be an important breakthrough path for the industrial production of high silicon steel. This technology can flow the molten steel liquid through a flat nozzle onto a high-speed rotating cooling copper roller. 5 At a cooling rate of 0.1 K / s, it rapidly solidifies into a thin ribbon, effectively suppressing the formation of an ordered phase and significantly improving the material's plasticity and uniformity. Currently, planar flow casting technology has been successfully applied to the industrial production of amorphous alloys, fully demonstrating its feasibility in terms of forming efficiency and cost control. Drawing on the mature process paths of the amorphous alloy industry, planar flow casting is used to prepare non-oriented high-silicon steel, and combined with subsequent flat rolling and annealing treatments, its magnetic properties are further optimized to meet the application requirements of high-performance soft magnetic materials for high-end electromagnetic components.

[0007] Therefore, developing a systematic plane flow casting preparation process for high silicon steel, from melting, temperature and pressure control to subsequent flat rolling and annealing heat treatment, can comprehensively solve the problems of high silicon steel in traditional processes such as high brittleness, difficult forming, and unstable performance. It has important theoretical value and engineering application significance. Summary of the Invention

[0008] The purpose of the present invention is to provide a high-silicon steel strip containing trace antimony and a planar flow casting preparation method thereof, which introduces trace antimony elements into high-silicon steel, utilizes the grain boundary segregation and surface segregation behavior of antimony, promotes the development of favorable textures, inhibits unfavorable textures and the oxidation behavior of the strip, and thus significantly improves the comprehensive magnetic properties of the material. The synergistic effect of the planar flow casting process and antimony microalloying overcomes the difficult problems of high brittleness and low yield in traditional processing of high-silicon steel, and effectively achieves uniform product thickness and improved surface quality through low-strain flat rolling with controlled reduction. This process is green and low-carbon, and the prepared high-silicon steel strip has excellent magnetic properties and is suitable for the manufacture of electromagnetic components such as high-frequency transformers and high-frequency inductors, and shows good application prospects in the fields of new energy power generation and electric vehicles.

[0009] To achieve the above purpose, the technical solution of the present invention is as follows:

[0010] The chemical composition of the trace antimony-containing high-silicon steel strip of the present invention is as follows by mass percentage: Si: 4.5-7.0%, Sb: 0.01-0.50%, C≤0.002%, N≤0.002%, O≤0.002%, S≤0.002%, and the remainder is Fe and unavoidable impurities. Finally, a non-oriented high-silicon steel strip with a thickness of 0.02-0.12 mm is prepared.

[0011] Furthermore, the magnetic properties of the non-oriented high silicon steel strip containing trace antimony meet the following requirements: magnetic induction intensity B8 ≥ 1.25T, iron loss P 10 / 400≤11.50W / kg, P 2 / 5000 ≤12.80W / kg;

[0012] The obtained non-oriented high-silicon steel thin strip containing trace antimony has a thickness tolerance of less than ±0.005mm and a surface roughness Ra≤0.8μm.

[0013] The specific steps of the invented planar flow casting method for preparing a high silicon steel strip containing trace antimony are as follows:

[0014] 1) Melting: Weigh each raw material according to the designed chemical composition, accurately melt it at 1550-1650℃, and cast it into a master alloy with uniform composition;

[0015] 2) Remelting and holding: placing the master alloy obtained in step 1) in a planar flow casting device under the protection of an inert gas or a covering agent, heating, remelting, and holding the temperature;

[0016] 3) Pressure control: A pressure control system is used to apply pressure on the molten steel according to the superheat of the molten steel;

[0017] 4) Plane casting: Under pressure, the molten steel is cast onto a rotating cooling copper roller through a flat nozzle at the bottom of the equipment to obtain an initial antimony-containing high-silicon steel strip with a thickness of 0.03 to 0.15 mm;

[0018] 5) Temper rolling: Temper rolling the high silicon steel strip obtained in step 4) at room temperature;

[0019] 6) Annealing: The high silicon steel strip after the temper rolling in step 5) is subjected to annealing to obtain a finished strip with a thickness of 0.02 to 0.12 mm.

[0020] Furthermore, the inert gas in step 2) is argon or nitrogen; the covering agent is a CaO-Al2O3-SiO2 basic molten steel covering agent; and the remelting and holding temperature is controlled between 1490 and 1600°C.

[0021] Furthermore, the superheat of the molten steel in step 3) is controlled between 30 and 140° C. using an infrared thermometer, and the corresponding applied pressure is 30 to 200 kPa, with a pressure control accuracy of ±5 kPa.

[0022] Furthermore, in step 4), the distance between the nozzle and the cooling copper roller is 0.3-2.0 mm, and the rotation speed of the cooling copper roller is 300-1500 rpm.

[0023] Furthermore, the total reduction of the temper rolling in step 5) is ≤30%, preferably in the range of 10 to 30%.

[0024] Furthermore, step 6) annealing is carried out in a reducing atmosphere of a H2+N2 mixed gas with a gas volume ratio VH2 :V N2 is 1:3 to 3:1, the annealing temperature is 950 to 1200 °C, the annealing time is 0.5 to 3 h, and it is cooled to room temperature in the furnace after annealing.

[0025] The technical principle of the present invention lies in:

[0026] (1) Grain boundary and surface segregation of antimony element: During the annealing process of high-silicon steel, antimony element is prone to segregate at grain boundaries and surfaces, inhibiting the nucleation of unfavorable {111} texture components, promoting the growth of favorable {100} components, optimizing the texture characteristics of high-silicon steel, and improving the magnetic properties of high-silicon steel. (2) Rapid solidification of strip casting: The strip casting process realizes rapid solidification through high-speed cooling, which can inhibit the formation of ordered phases in high-silicon steel, significantly improve the plasticity of the material during cold working, and improve the subsequent rolling processability. (3) Antimony element inhibits strip oxidation: Antimony has the property of inhibiting oxygen diffusion, which can reduce the generation of oxides in steel, especially during strip casting and annealing, reducing the adverse effects of oxidation on magnetic properties and improving the magnetic properties of high-silicon steel. (4) Precise control of skin pass rolling and heat treatment: Adopting a precise control skin pass rolling process with a total reduction of no more than 30%, effectively eliminating the surface defects of the cast strip, improving the surface quality and thickness uniformity, and at the same time enhancing the driving force for grain growth during subsequent heat treatment, preparing a non-oriented high-silicon steel thin strip material with uniform structure and excellent comprehensive magnetic properties containing trace amounts of antimony.

[0027] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0028] (1) Good magnetic properties: Through the grain boundary segregation and surface segregation of antimony element, the formation of unfavorable textures is effectively inhibited, and the comprehensive magnetic properties of high-silicon steel are significantly improved, which is widely applicable to the manufacture of electromagnetic components such as high-frequency transformers and motor cores.

[0029] (2) Significantly improved processing performance: The rapid solidification of strip casting inhibits the formation of ordered phases, making the final thin strip have good plasticity and processability.

[0030] (3) Optimized surface quality: The inhibitory effect of antimony element on oxygen effectively reduces the oxidation phenomenon during casting and annealing, ensuring that the surface of the thin strip is dense and has a low oxygen content, meeting the requirements of subsequent insulation treatment and electromagnetic applications.

[0031] (4) Green and low-carbon process: The process flow of the present invention is simplified, and energy conservation and consumption reduction are obvious. The strip casting process not only improves production efficiency but also reduces energy consumption, which is an environmentally friendly and efficient production method.

[0032] (5) Wide application prospects: The high-silicon steel strip prepared by this method has excellent magnetic properties and processing performance, and is especially suitable for fields such as high-frequency transformers, high-frequency inductors, new energy power generation, and electric vehicles, with broad market prospects. Brief Description of the Drawings

[0033] Figure 1 It is a schematic flow chart of the method for preparing the high-silicon steel strip containing trace antimony and its planar flow casting of the present invention.

[0034] Figure 2 It is a B-H curve graph of the magnetic induction and iron loss of the high-silicon steel strip after annealing in Example 1 of the present invention. Detailed Embodiments

[0035] The present invention will be further described below in conjunction with the embodiments:

[0036] Example 1:

[0037] The chemical composition mass percentage of the high-silicon steel is: Si: 6.60%, Sb: 0.11%, C, N, O, S are all ≤ 0.002%, and the rest are Fe and inevitable impurity elements. The preparation steps are as follows:

[0038] 1) Melting: Melting at 1600 °C and casting into a master alloy with uniform composition;

[0039] 2) Remelting and heat preservation: Remelting and heat preservation at 1510 °C under argon protection;

[0040] 3) Pressure control: The superheat of the molten steel is controlled at 50 °C, and the applied pressure is 60 kPa;

[0041] 4) Planar flow casting: The distance between the nozzle and the copper roll is 1.0 mm, the rotation speed of the copper roll is 800 rpm, and an initial strip with a thickness of 0.070 mm is prepared;

[0042] 5) Skin pass rolling: The total reduction is 20%;

[0043] 6) Heat treatment: The strip after skin pass rolling is annealed at 1000 °C for 1 h in a reducing atmosphere of V H2 :V N2 = 3:1 to obtain a finished strip with a thickness of 0.056 mm.

[0044] The magnetic induction B8 of the finished strip: 1.28 T, the iron loss P 10 / 400 : 7.73 W / kg, P 2 / 5000 : 9.93 W / kg; The thickness tolerance of the finished strip is ±0.004 mm, Ra = 0.77 μm.

[0045] Example 2:

[0046] The chemical composition of the high-silicon steel strip in mass percentage is: Si: 5.23%, Sb: 0.18%, C, N, O, S are all ≤ 0.002%, and the rest are Fe and inevitable impurity elements. The specific steps of this method are as follows:

[0047] 1) Melting: Melting at 1630 °C and casting into a master alloy with uniform composition;

[0048] 2) Remelting and heat preservation: Remelting and heat preserving at 1530 °C under nitrogen protection;

[0049] 3) Pressure control: The superheat of the molten steel is controlled at 70 °C, and the applied pressure is 90 kPa;

[0050] 4) Planar flow casting: The distance between the nozzle and the copper roll is 1.2 mm, the rotational speed of the copper roll is 1000 rpm, and an initial thin strip with a thickness of 0.085 mm is prepared;

[0051] 5) Skin pass rolling: The total reduction is 25%;

[0052] 6) Heat treatment: The thin strip after skin pass rolling is annealed at 950 °C for 3 h in a reducing atmosphere with V H2 :V N2 = 1:1 to obtain a finished thin strip with a thickness of 0.064 mm.

[0053] The magnetic induction B8 of the finished thin strip is 1.30 T, and the iron losses P 10 / 400 : 8.56 W / kg, P 2 / 5000 : 11.21 W / kg; the thickness tolerance of the finished thin strip is ±0.004 mm, and Ra = 0.78 μm.

[0054] Example 3:

[0055] The chemical composition of the high-silicon steel in mass percentage is: Si: 6.97%, Sb: 0.01%, C, N, O, S are all ≤ 0.002%, and the rest are Fe and inevitable impurity elements. The preparation steps are as follows:

[0056] 1) Melting: Melting at 1550 °C and casting into a master alloy with uniform composition;

[0057] 2) Remelting and heat preservation: Remelting and heat preserving at 1600 °C under the protection of a CaO - Al2O3 - SiO2 covering agent;

[0058] 3) Pressure control: The superheat of the molten steel is controlled at 140 °C, and the applied pressure is 30 kPa;

[0059] 4) Planar flow casting: The distance between the nozzle and the copper roll is 0.3 mm, the rotational speed of the copper roll is 1500 rpm, and an initial thin strip with a thickness of 0.030 mm is prepared;

[0060] 5) Skin pass rolling: total reduction is 30%;

[0061] 6) Heat treatment: The thin strip after skin pass rolling is annealed at 1200 °C for 0.5 h in a reducing atmosphere with V H2 :V N2 = 2:1 to obtain a finished thin strip with a thickness of 0.020 mm.

[0062] Magnetic induction B8 of the finished thin strip: 1.25 T, iron loss P 10 / 400 : 6.95 W / kg, P 2 / 5000 : 8.63 W / kg; thickness tolerance of the finished thin strip is ±0.003 mm, Ra = 0.73 μm.

[0063] Example 4:

[0064] The chemical composition mass percentage of high silicon steel is: Si: 5.80%, Sb: 0.36%, C, N, O, S are all ≤ 0.002%, and the rest are Fe and unavoidable impurity elements. The preparation steps are as follows:

[0065] 1) Melting: Melting at 1580 °C and casting into a master alloy with uniform composition;

[0066] 2) Remelting and holding: Remelting and holding at 1520 °C under argon protection;

[0067] 3) Pressure control: Superheat of the molten steel is controlled at 60 °C, and the applied pressure is 110 kPa;

[0068] 4) Planar flow casting: The distance between the nozzle and the copper roll is 1.4 mm, the copper roll rotation speed is 600 rpm, and an initial thin strip with a thickness of 0.125 mm is prepared;

[0069] 5) Skin pass rolling: total reduction is 20%;

[0070] 6) Heat treatment: The thin strip after skin pass rolling is annealed at 1050 °C for 2 h in a reducing atmosphere with V H2 :V N2 = 1:2 to obtain a finished thin strip with a thickness of 0.100 mm.

[0071] Magnetic induction B8 of the finished thin strip: 1.32 T, iron loss P 10 / 400 : 10.48 W / kg, P 2 / 5000 : 12.36 W / kg; thickness tolerance of the finished thin strip is ±0.005 mm, Ra = 0.80 μm.

[0072] Example 5:

[0073] The chemical composition of the high-silicon steel in mass percentage is: Si: 6.34%, Sb: 0.05%, C, N, O, S are all ≤ 0.002%, and the rest are Fe and inevitable impurity elements. The preparation steps are as follows:

[0074] 1) Melting: Melting at 1620 °C and casting into a master alloy with uniform composition;

[0075] 2) Remelting and heat preservation: Remelting and heat preserving at 1580 °C under nitrogen protection;

[0076] 3) Pressure control: The superheat of the molten steel is controlled at 120 °C, and the applied pressure is 40 kPa;

[0077] 4) Planar flow casting: The distance between the nozzle and the copper roll is 0.5 mm, the rotational speed of the copper roll is 1200 rpm, and an initial thin strip with a thickness of 0.035 mm is prepared;

[0078] 5) Skin pass rolling: The total reduction is 18%;

[0079] 6) Heat treatment: The thin strip after skin pass rolling is annealed at 1150 °C for 1.5 h in a reducing atmosphere with V H2 :V N2 = 2:1, and a finished thin strip with a thickness of 0.025 mm is obtained.

[0080] The magnetic induction B8 of the finished thin strip: 1.27 T, the iron loss P 10 / 400 : 7.43 W / kg, P 2 / 5000 : 9.37 W / kg; The thickness tolerance of the finished thin strip is ±0.003 mm, Ra = 0.74 μm.

[0081] Example 6:

[0082] The chemical composition of the high-silicon steel in mass percentage is: Si: 4.51%, Sb: 0.50%, C, N, O, S are all ≤ 0.002%, and the rest are Fe and inevitable impurity elements. The preparation steps are as follows:

[0083] 1) Melting: Melting at 1650 °C and casting into a master alloy with uniform composition;

[0084] 2) Remelting and heat preservation: Remelting and heat preserving at 1495 °C under the protection of a CaO-Al2O3-SiO2 covering agent;

[0085] 3) Pressure control: The superheat of the molten steel is controlled at 35 °C, and the applied pressure is 200 kPa;

[0086] 4) Planar flow casting: The distance between the nozzle and the copper roll is 2.0 mm, the rotational speed of the copper roll is 300 rpm, and an initial thin strip with a thickness of 0.150 mm is prepared;

[0087] 5) Skin pass rolling: total reduction is 20%;

[0088] 6) Heat treatment: the thin strip after skin pass rolling is annealed at 950 °C for 2 h in a reducing atmosphere with V H2 :V N2 = 1:3 to obtain a finished thin strip with a thickness of 0.120 mm.

[0089] Magnetic induction B8 of the finished thin strip: 1.35 T, iron loss P 10 / 400 : 11.45 W / kg, P 2 / 5000 : 12.80 W / kg; thickness tolerance of the finished thin strip is ±0.005 mm, Ra = 0.80 μm.

Claims

1. A high-silicon steel thin strip containing trace antimony, characterized in that, The chemical composition of the high-silicon steel strip is as follows by mass percentage: Si: 4.5 - 7.0%, Sb: 0.01 - 0.50%, C ≤ 0.002%, N ≤ 0.002%, O ≤ 0.002%, S ≤ 0.002%, and the balance is Fe and unavoidable impurities.

2. The thin strip of high-silicon steel containing trace antimony according to claim 1, characterized in that, Magnetic induction intensity B8 ≥ 1.25 T, iron loss P 10 / 400 ≤ 11.50 W / kg, P 2 / 5000 ≤ 12.80 W / kg; the thickness tolerance of the thin strip is ±0.005 mm, and the surface roughness Ra ≤ 0.8 μm.

3. A method for preparing a thin strip of high-silicon steel containing trace antimony by planar flow casting as described in claim 1 or 2, characterized in that, It includes the following specific steps: 1) Melting: Weigh each chemical raw material according to the designed ratio, precisely smelt the raw materials at a temperature of 1550 - 1650 °C, and cast them into a master alloy with uniform composition. 2) Remelting and heat preservation: Under the protection of inert gas or flux, place the master alloy obtained in step 1) into a planar flow casting device for heating, remelting, and heat preservation. 3) Pressure control: Through the equipment pressure control system, apply pressure above the molten steel according to the superheat of the molten steel. 4) Planar flow casting: Under pressurized conditions, cast the molten steel through a planar nozzle below the equipment onto a rotating cooling copper roll to obtain an initial high-silicon steel strip containing antimony with a thickness of 0.03 - 0.15 mm. 5) Skin pass rolling: Perform skin pass rolling on the high-silicon steel strip obtained in step 4) at room temperature. 6) Annealing treatment: Anneal the high-silicon steel strip after skin pass rolling in step 5) to obtain a finished strip with a thickness of 0.02 - 0.12 mm.

4. The planar flow casting preparation method of the high-silicon steel strip containing trace antimony according to claim 3, characterized in that, The inert gas in step 2) is argon or nitrogen; the flux is a CaO - Al2O3 - SiO2-based basic steel flux; the remelting and heat preservation temperature is controlled between 1490 - 1600 °C.

5. The planar flow casting preparation method of the high-silicon steel strip containing trace antimony according to claim 3, characterized in that, In step 3), the superheat of the molten steel is controlled between 30 - 140 °C by an infrared thermometer, and the corresponding applied pressure is 30 - 200 kPa, with a control accuracy of ±5 kPa.

6. According to the planar flow casting preparation method of the high-silicon steel strip containing trace antimony as described in claim 3, the distance between the nozzle and the cooling copper roll in step 4) is 0.3 - 2.0 mm, and the rotation speed of the cooling copper roll is 300 - 1500 rpm.

7. The planar flow casting preparation method of the high-silicon steel strip containing trace antimony according to claim 3, wherein, The total reduction range of the skin pass rolling in step 5) is 10 - 30%.

8. The planar flow casting preparation method of the high-silicon steel strip containing trace antimony according to claim 3, characterized in that, Step 6) The annealing treatment is carried out in a reducing atmosphere of a H2 + N2 mixed gas, and the gas volume ratio V H2 :V N2 is 1:3 to 3:1, the annealing temperature is 950 to 1200 °C, the annealing time is 0.5 to 3 h, and after annealing, it is cooled to room temperature with the furnace.

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