Non-oriented electrical steel and method of manufacturing the same

Abstract

The present application provides a non-oriented electrical steel containing the following elements by weight percentage: C: ≤0.005%, Si: 3.0%-3.8%, Mn: 0.20%-0.85%, Al: 0.4%-1.0%, 0 1.0 / 400 ≤12W / kg, magnetic induction B 50 1.62T-1.70T, yield strength R el 400MPa-470MPa, tensile strength R m 500MPa-600MPa, which can meet the demand of high magnetic induction and low iron loss for high speed and high efficiency motor.

Description

Technical Field

[0001] This application relates to the field of electrical steel technology, and in particular to a non-oriented electrical steel and its manufacturing method. Background Technology

[0002] In recent years, various electronic devices, especially small aircraft and new energy vehicles, have placed higher demands on motor performance: motors need to have low iron loss and high magnetic flux density while maintaining high speed and high efficiency. Accordingly, non-oriented electrical steel, as a key material for motor cores, needs to meet good comprehensive properties such as high strength, low iron loss, and high magnetic flux density in order to satisfy the above application requirements.

[0003] Existing technologies often employ increasing the silicon and aluminum content in non-oriented electrical steel to reduce eddy current and hysteresis losses. While increasing the silicon and aluminum content improves product strength and reduces iron losses, making it suitable for general industrial motors and generator sets, it also reduces the magnetic flux density of the electrical steel, making it unsuitable for high-speed motors in small aircraft and new energy vehicles. Therefore, developing non-oriented electrical steel with high magnetic flux density and low magnetic loss has become a research hotspot.

[0004] In recent years, there have been many reports on the development of non-oriented electrical steel with high magnetic induction and low magnetic loss. For example, patent CN108531813A discloses a cold-rolled non-oriented electrical steel for drive motors of new energy vehicles and its production method. The chemical composition of the material by weight percentage is: C: 0.0039%, Si: 2.82%, Mn: 0.18%, P≤0.04%, Als: 0.62%, S≤0.005%, N≤0.005%, Ti≤0.005%, with the remainder being Fe and unavoidable impurities. The production method involves casting, hot rolling, normalizing and pickling, cold rolling, annealing, and coating of molten steel to obtain the finished steel strip. The finished steel strip B... 5000 ≥1.65T, P 1.0 / 400 ≤17W / kg. Although the electrical steel has a high magnetic induction, its iron loss is still relatively high.

[0005] Patent CN112322972A discloses a method for improving the comprehensive performance of high-strength non-oriented high-silicon steel through normalizing treatment. The chemical composition of the material (by weight percentage) is: C≤0.50%, Si=3.5%~5.5%, Mn≤0.50%, S≤0.002%, Ti≤0.0030%, P≤0.30%, B≤0.0020%, with the balance being iron. The material uses only silicon as a solid solution strengthening element, without adding other alloying elements, thus reducing costs and saving resources. The magnetic induction intensity B of the finished high-strength non-oriented electrical steel sheet is... 50 =1.58T~1.68T, iron loss value P 1.0 / 400=15W / kg~40W / kg, yield strength is 540MPa~1060MPa. Although this electrical steel has high strength and high magnetic induction, its iron loss is still high.

[0006] Patent CN113981329A discloses a low-iron-loss, high-strength non-oriented electrical steel for drive motors of new energy vehicles and its manufacturing method. The chemical composition of the material by weight percentage is: C: 0.001%–0.005%, Si: 2.4%–3.0%, Mn: 0.25%–0.5%, Al: 0.70%–1.10%, P: ≤0.02%, S: ≤0.005%, 0.015% ≤ Ce + Sn ≤ 0.035%, with the balance being iron and unavoidable impurities. This method purifies the molten steel by adding Ce and Sn, and improves the strength and magnetic properties of the non-oriented electrical steel through micro-alloying, ultimately producing a finished plate with a thickness of 0.35 mm. 50 The W is between 1.67T and 1.74T. 10 / 400 The strength ranges from 16.5 W / kg to 21.5 W / kg, with a yield strength of 660 MPa to 745 MPa. Rare earth elements are added to this electrical steel to optimize the texture and grain size of the finished product, thereby improving its magnetic properties. However, this results in extremely high production costs in industrial manufacturing, making large-scale industrial application difficult. Furthermore, its relatively large thickness makes it unsuitable for medium- and high-frequency applications.

[0007] It is evident that the existing technologies for non-oriented electrical steel and their preparation methods cannot simultaneously achieve the excellent properties of low iron loss and high magnetic induction, making it difficult to meet the application requirements of high-speed, high-efficiency motors. Summary of the Invention

[0008] This application is made in view of the above-mentioned problems, and its purpose is to provide a non-oriented electrical steel and a method for manufacturing the same, which has high magnetic induction and low iron loss.

[0009] Specifically, the first aspect of this application provides a non-oriented electrical steel containing the following elements by weight percentage: C: ≤0.005%, Si: 3.0%~3.8%, Mn: 0.20%~0.85%, Al: 0.4%~1.0%, 0<P≤0.02%, S: ≤0.0009%, N: ≤0.0009%, with the balance being iron and unavoidable impurities.

[0010] This application increases the Si content to 3.0%–3.8% and strictly controls the content of impurity elements such as C, S, N, and Ti in the molten steel. At the same time, the reasonable ratio of Al, Mn, and P elements results in a material with high magnetic induction and low iron loss.

[0011] Optionally, the weight percentage of Si is 3.2% to 3.8%.

[0012] This application can significantly reduce eddy current losses and produce a stronger solid solution strengthening effect by increasing the Si content to more than 3.2%. If it is controlled within 3.8%, it can avoid abnormally high hysteresis losses caused by excessive grain refinement or brittleness.

[0013] Optionally, the Mn content is preferably 0.20% to 0.65%.

[0014] Optionally, the Al is preferably 0.5% to 0.8%.

[0015] Optionally, the thickness of the non-oriented electrical steel is 0.1 mm to 0.2 mm.

[0016] Optionally, the average grain size of the non-oriented electrical steel is 70 μm to 160 μm.

[0017] Optionally, the B of the non-oriented electrical steel 50 The range is 1.62T to 1.70T.

[0018] Optionally, the P of the non-oriented electrical steel 1.0 / 400 ≤12W / Kg.

[0019] Optionally, the yield strength R of the non-oriented electrical steel el Tensile strength R is 400MPa~470MPa. m The elongation is 500MPa to 600MPa. 50 It ranges from 10% to 20%.

[0020] The second aspect of this application provides a method for manufacturing non-oriented electrical steel, comprising the steps of smelting, hot rolling, normalizing pickling, cold rolling, and annealing molten steel.

[0021] Optionally, the C+S+N+Ti in the molten steel is ≤0.004%.

[0022] Optionally, the hot rolling includes heat treatment, rolling, and coiling.

[0023] Optionally, the normalizing pickling includes pretreatment, normalizing, and pickling.

[0024] Optionally, the cold rolling reduction rate is 70% to 95%.

[0025] Optionally, the annealing is carried out in an annealing furnace at a temperature of 800℃ to 1050℃.

[0026] Optionally, the annealing process further includes applying an insulating material, which is a semi-organic coating.

[0027] Optionally, the heating temperature of the heat treatment is 1000℃~1200℃.

[0028] Optionally, the final rolling temperature is 800℃~960℃.

[0029] Optionally, the thickness of the rolled hot plate is 1.6 mm to 3.0 mm.

[0030] Optionally, the winding temperature is 500℃~750℃.

[0031] Optionally, the pretreatment involves trimming the steel plate before the normalizing pickling step, with a trimming width of 5mm to 10mm on each side.

[0032] Optionally, the normalizing temperature is 850℃~950℃, and the holding time is 30s~300s.

[0033] Optionally, the pickling solution is hydrochloric acid, and the pickling temperature is 40℃~90℃.

[0034] Optionally, the dew point inside the annealing furnace is -40℃ to -10℃.

[0035] Optionally, the internal tension of the annealing furnace is 0.1 MPa to 9 MPa.

[0036] Compared with the prior art, the present invention has the following beneficial effects: This invention significantly improves the resistivity of steel and reduces eddy current losses at high frequencies by increasing the Si content to 3.0%–3.8% and strictly controlling the content of impurity elements such as C, S, N, and Ti in the molten steel. Simultaneously, a reasonable ratio of Al, Mn, and P elements helps improve the texture, allowing the material to maintain high magnetic induction (B... 50 While achieving a torque of 1.62T to 1.70T, it also achieved extremely low iron loss (P0.05). 1.0 / 400 With a strength of ≤12W / Kg, it can meet the requirements of high-speed, high-efficiency motors for low iron loss and high magnetic induction.

[0037] While ensuring magnetic properties, this invention achieves a yield strength of 400MPa to 470MPa and a tensile strength of 500MPa to 600MPa in the final product through high Si solid solution strengthening and P element microalloying, combined with an optimized full-process manufacturing process. This makes it suitable for high-speed, high-efficiency motor applications.

[0038] This invention eliminates the need for adding rare earth elements or other precious elements. By selecting alloy composition, using appropriate hot rolling heating temperature, cold rolling process, and final annealing temperature, as well as controlling inclusions and grain size, non-oriented electrical steel exhibits high magnetic induction and low iron loss. It also helps reduce losses in high-speed drive motors, improves motor efficiency, and saves a significant amount of energy. The manufacturing method is simple and feasible, easy to industrialize, and has high practical and economic value. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this drawing 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 drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0040] Figure 1 The image shows the metallographic structure of the non-oriented electrical steel obtained in Example 5. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the following description and illustration are provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0042] Obviously, the following description is merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0043] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0044] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0045] On one hand, embodiments of this application provide a non-oriented electrical steel containing the following elements by weight percentage: C: ≤0.005%, Si: 3.0%~3.8%, Mn: 0.20%~0.85%, Al: 0.4%~1.0%, O<P≤0.02%, S: ≤0.0009%, N: ≤0.0009%, with the balance being iron and unavoidable impurities.

[0046] The non-oriented electrical steel provided in this application has the following control mechanism and effect on the content of its relevant components: C: In electrical steel, carbon (C) is the main element causing magnetic aging. Whether present in solid solution or cementite form, C impairs the magnetic properties of the steel. A high residual C content in the steel leads to increased coercivity and hysteresis loss, and also causes magnetic aging. Therefore, the carbon content in the finished product should be as low as possible. This invention limits the C content to below 0.005%.

[0047] Si: The main function of Si is to increase the resistivity of electrical steel and reduce iron loss. However, excessive Si content increases the difficulty of surface quality control of hot-rolled coils and worsens rollability. Therefore, this invention controls the Si content to be 3.0% to 3.8%, preferably 3.2% to 3.8%.

[0048] Mn: Mn is beneficial for increasing the resistivity of electrical steel, reducing iron loss, and improving the rollability of hot-rolled plates. However, excessive Mn reduces saturation magnetization. Therefore, the Mn content in this invention is set at 0.20% to 0.85%, preferably 0.20% to 0.65%.

[0049] Al: Al is soluble in ferrite, which increases resistivity, reduces iron loss, and improves yield strength. However, excessive Al content can cause molten steel to become sticky, making casting difficult. Therefore, this invention controls the Al content to be 0.4%–1.0%, preferably 0.5%–0.8%.

[0050] P: P can refine grains, increase strength, and improve texture, but excessive P, especially at very low carbon content, can cause Fe3P segregation, leading to embrittlement of electrical steel and reduced toughness. Therefore, this invention controls 0 < P ≤ 0.02%.

[0051] S: S is a harmful element. It easily forms plastic MnS with Mn, which can alleviate hot brittleness, but it also causes the strip to form a banded structure, reducing the toughness and formability of electrical steel. Furthermore, MnS can strongly hinder grain growth during the annealing of non-oriented electrical steel, thus affecting its magnetic properties. Therefore, this invention controls the S content to ≤0.0009%.

[0052] Nitrogen (N): Nitrogen is an element that causes magnetic aging. It readily combines with Al to form fine AlN precipitates, inhibiting grain growth and affecting magnetic properties. A key objective of heating, hot rolling, and annealing processes is to prevent the precipitation of fine AlN or to coarsen existing AlN in the steel. Therefore, this invention controls the N content to ≤0.0009%.

[0053] In some embodiments of this application, the thickness of the non-oriented electrical steel is 0.1 mm to 0.2 mm.

[0054] In some embodiments of this application, the average grain size of the non-oriented electrical steel is 70 μm to 160 μm.

[0055] In some embodiments of this application, the minimum magnetic flux density of the non-oriented electrical steel is 1.62T to 1.70T. Here, minimum magnetic flux density refers to the minimum magnetic flux density at which the material is magnetized under a 1.5T magnetic field. A minimum magnetic flux density within this range for the non-oriented electrical steel is beneficial for improving its magnetic properties.

[0056] In some embodiments of this application, the maximum iron loss of the non-oriented electrical steel is 12 W / kg. Here, maximum iron loss refers to the maximum core loss value when the material is magnetized to 1.0T at a frequency of 400 Hz. The maximum iron loss of the non-oriented electrical steel falling within this range is beneficial for improving its magnetic properties.

[0057] In some embodiments of this application, the yield strength R of the non-oriented electrical steel el The pressure ranges from 400 MPa to 470 MPa.

[0058] In some embodiments of this application, the tensile strength R of the non-oriented electrical steel m The pressure is 500MPa to 600MPa.

[0059] In some embodiments of this application, the elongation A of the non-oriented electrical steel is... 50 It ranges from 10% to 20%.

[0060] On the other hand, this application provides a method for manufacturing non-oriented electrical steel, the specific steps of which include: smelting molten steel, hot rolling, normalizing pickling, cold rolling and annealing.

[0061] In some embodiments of this application, the impurity elements in the molten steel are controlled to be C+S+N+Ti≤0.004%.

[0062] In some embodiments of this application, the hot rolling includes heat treatment, rolling, and coiling.

[0063] A suitable hot rolling process can refine the grains of non-oriented electrical steel, making the stress distribution inside the material more uniform, avoiding the increase of magnetic domain wall movement resistance, and further reducing hysteresis loss. A suitable hot rolling process is conducive to the formation of specific crystal textures. By controlling parameters such as rolling temperature during the hot rolling process, the development of favorable textures such as (110) <001> can be promoted, making the magnetic properties of non-oriented electrical steel more uniform in all directions and improving the magnetic induction intensity of non-oriented electrical steel.

[0064] In some embodiments of this application, the normalizing pickling includes pretreatment, normalizing, and pickling.

[0065] In some embodiments of this application, the cold rolling reduction rate is 70% to 95%.

[0066] In some embodiments of this application, the annealing is performed in an annealing furnace at a temperature of 800°C to 1050°C.

[0067] The positive effects of controlling the annealing temperature to 800℃~1050℃: If the annealing temperature is too high, the finished product grains will be coarse, the high-frequency iron loss will be significantly increased, which is not conducive to the application of the material in high-speed motors. If the annealing temperature is too low, the grains cannot complete recrystallization, the material structure may have deformed structure, and the magnetic properties will be greatly deteriorated.

[0068] In some embodiments of this application, the annealing process further includes applying an insulating material, which is a semi-organic coating.

[0069] In some embodiments of this application, the heating temperature of the heat treatment is 1000℃~1200℃.

[0070] The positive effects of controlling the heating temperature to 1000℃~1200℃ are as follows: Heating temperatures above 1200℃ can cause AlN to re-solidify and re-precipitate in subsequent processes, deteriorating its magnetic properties; heating temperatures below 1000℃ result in high deformation resistance and heavy load on the hot rolling mill during subsequent hot rolling. Therefore, the heating temperature should be controlled to 1000℃~1200℃.

[0071] In some embodiments of this application, the final rolling temperature is 800°C to 960°C.

[0072] The positive effects of controlling the final rolling temperature to 800℃~960℃ are as follows: Excessively high final rolling temperatures lead to energy waste and increased surface oxide scale; excessively low final rolling temperatures increase the load on the hot rolling mill, affecting the shape of the hot-rolled plate. Therefore, controlling the final rolling temperature to 800℃~960℃ is crucial.

[0073] In some embodiments of this application, the thickness of the rolled hot plate is 1.6 mm to 3.0 mm.

[0074] The positive effects of controlling the thickness of the hot plate during rolling to be between 1.6 mm and 3.0 mm: If the thickness of the hot plate is greater than 3.0 mm, the processing volume of the subsequent cold rolling process will increase, reducing the efficiency of the cold rolling process. At the same time, the increased deformation in the cold rolling process will lead to the deterioration of the magnetic properties of the final product. If the thickness of the hot plate is less than 1.6 mm, the requirements for the plate shape control capability of the hot rolling mill will be too high, and the stability of hot rolling will be reduced.

[0075] In some embodiments of this application, the winding temperature is 500°C to 750°C.

[0076] The positive effects of controlling the coiling temperature between 500℃ and 750℃ are as follows: Excessive coiling temperature leads to energy waste and thickens the surface oxide scale; excessively low coiling temperature results in a high proportion of deformed microstructure in the hot-rolled sheet, affecting the steel's magnetic properties. Therefore, controlling the coiling temperature between 500℃ and 750℃ is crucial.

[0077] In some embodiments of this application, the pretreatment is to trim the steel plate before the normalizing pickling step, with the trimmed edge width being 5mm to 10mm on each side.

[0078] In some embodiments of this application, the normalization temperature is 850℃~950℃, and the holding time is 30s~300s.

[0079] The positive effects of controlling the normalizing temperature to 850℃~950℃: Normalizing can improve the uniformity of the microstructure and enhance the magnetic properties of the finished product. If the normalizing temperature is higher than 950℃, the cold rolling machinability of the steel coil will deteriorate for high-grade non-oriented electrical steel, and edge cracks or even strip breaks are likely to occur during the cold rolling process. If the normalizing temperature is lower than 850℃, the effect of normalizing is weakened, the recrystallization of the hot-rolled deformed microstructure cannot be completed, the microstructure uniformity will deteriorate, and it will also be detrimental to the improvement of the texture component and the deterioration of the magnetic properties.

[0080] The positive effects of controlling the holding time of normalizing treatment to 30s to 300s: If the normalizing time is less than 30s, the normalizing effect is weakened, the hot-rolled deformed structure cannot be recrystallized, the structure uniformity is worse, and it is also not conducive to the improvement of texture components and the magnetic properties are deteriorated; if the normalizing time exceeds 300s, it will waste resources and at the same time worsen the cold rolling processability.

[0081] In some embodiments of this application, the pickling solution is hydrochloric acid, and the pickling temperature is 40°C to 90°C.

[0082] In some embodiments of this application, the dew point inside the annealing furnace is -40°C to -10°C.

[0083] In some embodiments of this application, the internal tension of the annealing furnace is 0.1 MPa to 9 MPa.

[0084] Example The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0085] Example 1 The non-oriented electrical steel provided in this embodiment contains the following elements by weight percentage: C: 0.0011%, Si: 3.518%, Mn: 0.2931%, Al: 0.9255%, P: 0.0116%, S: 0.0005%, N: 0.0004%, with the balance being iron and unavoidable impurities.

[0086] The manufacturing method of non-oriented electrical steel provided in this embodiment includes the following steps: Smelting: Based on the chemical composition in Example 1 of Table 1, and controlling the impurity elements in the molten steel to C+S+N+Ti≤0.004%, the molten steel is desulfurized, smelted in a converter, treated with RH vacuum, and continuously cast into slabs; Hot rolling: The slab is heated to 1120℃, and the final rolling temperature is 905℃. It is then hot rolled into a 1.6mm thick hot-rolled plate, which is then coiled at 620℃ and held for 2 hours before air cooling. Normalizing and pickling: Normalizing and pickling includes pretreatment, normalizing, and pickling; pretreatment involves trimming the hot-rolled plate before the normalizing and pickling steps, with a trimming width of 6.1 mm on each side; the pretreated hot-rolled plate is then normalized at a temperature of 850℃ for 120 seconds; the normalized hot-rolled plate is then pickled using hydrochloric acid at a concentration of 10% at a temperature of 60℃. Cold rolling: The steel plate after normalizing and pickling is cold rolled with a reduction rate controlled at 90% to a final thickness of 0.15mm. Annealing: The cold-rolled sheet is annealed in an annealing furnace at a temperature of 1010℃ and a heating rate of 20℃ / s, and held at the annealing temperature for 130s. The annealing atmosphere is hydrogen with a volume content of 5% and the remainder is nitrogen. After holding, it is cooled to 20℃ at a cooling rate of 8℃ / s. The dew point inside the annealing furnace is controlled at -34℃ and the furnace tension is controlled at 4MPa. The surface of the annealed steel sheet is coated with Wuhan Iron and Steel T4 coating to obtain a finished product with a thickness of 0.15mm.

[0087] Example 2 The non-oriented electrical steel provided in this embodiment contains the following elements by weight percentage: C: 0.0013%, Si: 3.528%, Mn: 0.2931%, Al: 0.9255%, P: 0.0096%, S: 0.0008%, N: 0.0005%, with the balance being iron and unavoidable impurities.

[0088] The manufacturing method of non-oriented electrical steel provided in this embodiment includes the following steps: Smelting: Based on the chemical composition in Example 2 of Table 1, and controlling the impurity elements in the molten steel to C+S+N+Ti≤0.004%, the molten steel is desulfurized, smelted in a converter, treated with RH vacuum, and continuously cast into slabs; Hot rolling: The slab is heated to 1130℃, and the final rolling temperature is 903℃. It is then hot rolled into a 1.6mm thick hot-rolled plate, which is then coiled at 620℃ and held for 2 hours before air cooling. Normalizing and pickling: Normalizing and pickling includes pretreatment, normalizing, and pickling; pretreatment involves trimming the hot-rolled plate before the normalizing and pickling steps, with a trimming width of 6.3 mm on each side; the pretreated hot-rolled plate is then normalized at a temperature of 850℃ for 120 seconds; the normalized hot-rolled plate is then pickled using hydrochloric acid at a concentration of 10% at a temperature of 60℃. Cold rolling: The steel plate after normalizing and pickling is cold rolled with a reduction rate controlled at 90% to a final thickness of 0.15mm. Annealing: The cold-rolled sheet is annealed in an annealing furnace at a temperature of 1010℃ and a heating rate of 20℃ / s, and held at the annealing temperature for 130s. The annealing atmosphere is hydrogen with a volume content of 5% and the remainder is nitrogen. After holding, it is cooled to 20℃ at a cooling rate of 8℃ / s. The dew point inside the annealing furnace is controlled at -33℃ and the furnace tension is controlled at 5MPa. The surface of the annealed steel sheet is coated with Wuhan Iron and Steel T4 coating to obtain a finished product with a thickness of 0.15mm.

[0089] Example 3 The non-oriented electrical steel provided in this embodiment contains the following elements by weight percentage: C: 0.0011%, Si: 3.548%, Mn: 0.2931%, Al: 0.9255%, P: 0.0086%, S: 0.0006%, N: 0.0006%, with the balance being iron and unavoidable impurities.

[0090] The manufacturing method of non-oriented electrical steel provided in this embodiment includes the following steps: Smelting: Based on the chemical composition in Example 3 of Table 1, and controlling the impurity elements in the molten steel to C+S+N+Ti≤0.004%, the molten steel is desulfurized, smelted in a converter, treated with RH vacuum, and continuously cast into slabs; Hot rolling: The slab is heated to 1110℃ and the final rolling temperature is 895℃. It is then hot rolled into a 1.6mm thick hot-rolled plate, which is then coiled at 650℃ and held for 2 hours before air cooling. Normalizing and pickling: Normalizing and pickling includes pretreatment, normalizing, and pickling; pretreatment involves trimming the hot-rolled plate before the normalizing and pickling steps, with a trimming width of 6.5 mm on each side; the pretreated hot-rolled plate is then normalized at a temperature of 850℃ for 120 seconds; the normalized hot-rolled plate is then pickled using hydrochloric acid at a concentration of 10% at a temperature of 60℃. Cold rolling: The steel plate after normalizing and pickling is cold rolled with a reduction rate controlled at 90% to a final thickness of 0.15mm. Annealing: The cold-rolled sheet is annealed in an annealing furnace at a temperature of 1000℃ and a heating rate of 20℃ / s, and held at the annealing temperature for 130s. The annealing atmosphere is hydrogen with a volume content of 10% and the remainder is nitrogen. After holding, it is cooled to 20℃ at a cooling rate of 8℃ / s. The dew point inside the annealing furnace is controlled at -30℃ and the furnace tension is controlled at 4MPa. The surface of the annealed steel sheet is coated with Wuhan Iron and Steel T4 coating to obtain a finished product with a thickness of 0.15mm.

[0091] Example 4 The non-oriented electrical steel provided in this embodiment contains the following elements by weight percentage: C: 0.0009%, Si: 3.536%, Mn: 0.277%, Al: 0.9573%, P: 0.0126%, S: 0.0007%, N: 0.0005%, with the balance being iron and unavoidable impurities.

[0092] The manufacturing method of non-oriented electrical steel provided in this embodiment includes the following steps: Smelting: Based on the chemical composition in Example 4 of Table 1, and controlling the impurity elements in the molten steel to C+S+N+Ti≤0.004%, the molten steel was desulfurized, smelted in a converter, treated with RH vacuum, and continuously cast into slabs. Hot rolling: The slab is heated to 1110℃ and the final rolling temperature is 890℃. It is then hot rolled into a 1.6mm thick hot-rolled plate, which is then coiled at 650℃ and held for 2 hours before air cooling. Normalizing and pickling: Normalizing and pickling includes pretreatment, normalizing, and pickling; pretreatment involves trimming the hot-rolled plate before the normalizing and pickling steps, with a trimming width of 6.3 mm on each side; the pretreated hot-rolled plate is then normalized at a temperature of 850℃ for 120 seconds; the normalized hot-rolled plate is then pickled using hydrochloric acid at a concentration of 10% at a temperature of 60℃. Cold rolling: The steel plate after normalizing and pickling is cold rolled with a reduction rate controlled at 90% to a final thickness of 0.15mm. Annealing: The cold-rolled sheet is annealed in an annealing furnace at a temperature of 1000℃ and a heating rate of 20℃ / s, and held at the annealing temperature for 130s. The annealing atmosphere is hydrogen with a volume content of 10% and the remainder is nitrogen. After holding, it is cooled to 20℃ at a cooling rate of 8℃ / s. The dew point inside the annealing furnace is controlled at -30℃ and the furnace tension is controlled at 5MPa. The surface of the annealed steel sheet is coated with Wuhan Iron and Steel T4 coating to obtain a finished product with a thickness of 0.15mm.

[0093] Example 5 The non-oriented electrical steel provided in this embodiment contains the following elements by weight percentage: C: 0.0005%, Si: 3.505%, Mn: 0.3132%, Al: 0.8953%, P: 0.0136%, S: 0.0008%, N: 0.0007%, with the balance being iron and unavoidable impurities.

[0094] The manufacturing method of non-oriented electrical steel provided in this embodiment includes the following steps: Smelting: Based on the chemical composition in Example 5 of Table 1, and controlling the impurity elements in the molten steel to C+S+N+Ti≤0.004%, the molten steel is desulfurized, smelted in a converter, treated with RH vacuum, and continuously cast into slabs; Hot rolling: The slab is heated to 1140℃ and the final rolling temperature is 910℃. It is then hot rolled into a 1.6mm thick hot-rolled plate, which is then coiled at 680℃ and held for 2 hours before air cooling. Normalizing and pickling: Normalizing and pickling includes pretreatment, normalizing, and pickling; pretreatment involves trimming the hot-rolled plate before the normalizing and pickling steps, with a trimming width of 6.2 mm on each side; the pretreated hot-rolled plate is then normalized at a temperature of 850℃ for 120 seconds; the normalized hot-rolled plate is then pickled using hydrochloric acid at a concentration of 10% at a temperature of 60℃. Cold rolling: The steel plate after normalizing and pickling is cold rolled with a reduction rate controlled at 90% to a final thickness of 0.15mm. Annealing: The cold-rolled sheet is annealed in an annealing furnace at a temperature of 1020℃ and a heating rate of 20℃ / s, and held at the annealing temperature for 130s. The annealing atmosphere is hydrogen with a hydrogen volume content of 8% and the remainder is nitrogen. After holding, it is cooled to 20℃ at a cooling rate of 8℃ / s. The dew point inside the annealing furnace is controlled at -36℃ and the furnace tension is controlled at 3MPa. The surface of the annealed steel sheet is coated with Wuhan Iron and Steel T4 coating to finally obtain a 0.15mm finished product.

[0095] Figure 1 This is a metallographic image of the non-oriented electrical steel obtained in this embodiment.

[0096] Example 6 The non-oriented electrical steel provided in this embodiment contains the following elements by weight percentage: C: 0.0008%, Si: 3.515%, Mn: 0.3132%, Al: 0.8953%, P: 0.0106%, S: 0.0009%, N: 0.0009%, with the balance being iron and unavoidable impurities.

[0097] The manufacturing method of non-oriented electrical steel provided in this embodiment includes the following steps: Smelting: Based on the chemical composition in Example 6 of Table 1, and controlling the impurity elements in the molten steel to C+S+N+Ti≤0.004%, the molten steel was desulfurized, smelted in a converter, treated with RH vacuum, and continuously cast into slabs. Hot rolling: The slab is heated to 1140℃ and the final rolling temperature is 906℃. It is then hot rolled into a 1.6mm thick hot-rolled plate, which is then coiled at 680℃ and held for 2 hours before air cooling. Normalizing and pickling: Normalizing and pickling includes pretreatment, normalizing, and pickling; pretreatment involves trimming the hot-rolled plate before the normalizing and pickling steps, with a trimming width of 6.0 mm on each side; the pretreated hot-rolled plate is then normalized at a temperature of 850℃ for 120 seconds; the normalized hot-rolled plate is then pickled using hydrochloric acid at a concentration of 10% at a temperature of 60℃. Cold rolling: The steel plate after normalizing and pickling is cold rolled with a reduction rate controlled at 90% to a final thickness of 0.15mm. Annealing: The cold-rolled sheet is annealed in an annealing furnace at a temperature of 1020℃ and a heating rate of 20℃ / s, and held at the annealing temperature for 130s. The annealing atmosphere is hydrogen with a hydrogen volume content of 8% and the remainder is nitrogen. After holding, it is cooled to 20℃ at a cooling rate of 8℃ / s. The dew point inside the annealing furnace is controlled at -36℃ and the furnace tension is controlled at 2MPa. The surface of the annealed steel sheet is coated with Wuhan Iron and Steel T4 coating to obtain a finished product with a thickness of 0.15mm.

[0098] The element weight percentages of the non-oriented electrical steels in Examples 1-6 are shown in Table 1, and the process parameters are shown in Table 2.

[0099] Table 1 shows the weight percentage (wt%) of elements contained in the examples of non-oriented electrical steel.

[0100] Table 2 Process parameters for non-oriented electrical steel examples

[0101] The performance of the manufactured non-oriented electrical steel was evaluated.

[0102] (1) Mechanical property testing of non-oriented electrical steel: According to GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Test at room temperature", an electronic universal testing machine was used to process the non-oriented electrical steel into standard tensile specimens. The tensile speed was controlled between 0.00025 / s and 0.0025 / s. Force and displacement data during the tensile process were recorded, and the tensile strength R was calculated. m Yield strength R el and elongation A 50 .

[0103] (2) Testing of iron loss and magnetic properties of non-oriented electrical steel: Following GB / T 3655-2019 "Methods for Measuring the Magnetic Properties of Electrical Steel Sheets (Strips)," the power loss per unit weight of non-oriented electrical steel was measured using an Epstein square ring apparatus or a single-piece tester at a magnetic field strength of 400Hz and 1.0T. This power loss is the iron loss. The magnetic induction intensity of the non-oriented electrical steel was measured when the magnetic field strength reached 1.5T and recorded as B. 50 .

[0104] The evaluation results of each performance aspect are shown in Table 3.

[0105] Table 3 Performance test results of non-oriented electrical steel

[0106] As can be seen from the embodiments, the performance of the product manufactured according to the composition and production parameters of this application meets the requirements of B. 50The iron loss P is 1.62T~1.70T. 1.0 / 400 ≤12W / Kg, yield strength R el Tensile strength R is 400MPa~470MPa. m The elongation is 500MPa to 600MPa. 50 The content is 10% to 20%. Performance test results of the examples show that by selecting alloy composition, appropriate hot rolling heating temperature, cold rolling process and final annealing temperature, as well as controlling inclusions and grain size, non-oriented electrical steel can have excellent properties such as high magnetic strength and low iron loss.

[0107] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A non-oriented electrical steel, characterized in that, It contains the following elements by weight percentage: C: ≤0.005%, Si: 3.0%~3.8%, Mn: 0.20%~0.85%, Al: 0.4%~1.0%, O<P: ≤0.02%, S: ≤0.0009%, N: ≤0.0009%, with the balance being iron and unavoidable impurities.

2. The non-oriented electrical steel according to claim 1, characterized in that: The weight percentage of Si is 3.20% to 3.80%; And / or, the weight percentage of Mn is 0.20% to 0.65%; And / or, the weight percentage of Al is 0.5% to 0.8%.

3. The non-oriented electrical steel according to claim 1, characterized in that, The thickness of the non-oriented electrical steel is 0.1mm to 0.2mm.

4. The non-oriented electrical steel according to claim 1, characterized in that, The average grain size of the non-oriented electrical steel is 70μm to 160μm.

5. The non-oriented electrical steel according to claim 1, characterized in that, B of the non-oriented electrical steel 50 The range is 1.62T to 1.70T; And / or, the P of the non-oriented electrical steel 1.0 / 400 ≤12W / Kg.

6. The non-oriented electrical steel according to claim 1, characterized in that, The yield strength R of the non-oriented electrical steel el The pressure ranges from 400 MPa to 470 MPa. And / or, the tensile strength R of the non-oriented electrical steel m The pressure is 500MPa to 600MPa. And / or, the elongation A of the non-oriented electrical steel 50 It ranges from 10% to 20%.

7. The method for manufacturing non-oriented electrical steel according to any one of claims 1 to 6, characterized in that, The specific steps include: smelting molten steel, hot rolling, normalizing and pickling, cold rolling and annealing.

8. The method for manufacturing non-oriented electrical steel according to claim 7, characterized in that, The molten steel contains C+S+N+Ti≤0.004%.

9. The method for manufacturing non-oriented electrical steel according to claim 7, characterized in that, The hot rolling process includes heat treatment, rolling, and coiling; And / or, the normalizing pickling includes pretreatment, normalizing, and pickling; And / or, the cold rolling reduction rate is 70% to 95%; And / or, the annealing is performed in an annealing furnace at a temperature of 800°C to 1050°C; And / or, the annealing process further includes applying an insulating material, which is a semi-organic coating.

10. The method for manufacturing non-oriented electrical steel according to claim 9, characterized in that, The heating temperature for the heat treatment is 1000℃~1200℃; And / or, the final rolling temperature is 800℃~960℃; And / or, the thickness of the rolled hot plate is 1.6 mm to 3.0 mm; And / or, the winding temperature is 500℃~750℃; And / or, the pretreatment is to trim the steel plate before the normalizing pickling step, with a trim width of 5mm to 10mm on each side; And / or, the normalization temperature is 850℃~950℃, and the holding time is 30s~300s; And / or, the pickling solution is hydrochloric acid, and the pickling temperature is 40℃~90℃; And / or, the dew point inside the annealing furnace is -40℃ to -10℃; And / or, the internal tension of the annealing furnace is 0.1 MPa to 9 MPa.

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