Non-oriented electrical steel with excellent overall performance and its manufacturing method

Abstract

The present disclosure provides a non-oriented electrical steel with excellent overall performance, which contains, in addition to Fe and inevitable impurities, the following chemical elements by mass percentage: C≦0.0050%, Si: 3.10-4.50%, Al: 0.10%-2.00%, Mn: 0.10%-2.50%, and 3.75%≦Si+Al≦5.22%. Correspondingly, the present disclosure also discloses a method for producing the non-oriented electrical steel. The non-oriented electrical steel has small magnetic anisotropy, high magnetic induction strength, small iron loss at medium and high frequencies, and high yield strength, making it suitable for use as an iron core material in electric vehicle drive motors, high-speed motors, unmanned aerial vehicles, and the like.

Description

[Technical Field]

[0001] The present disclosure relates to a steel sheet and a manufacturing method thereof, and more particularly to a non-oriented electrical steel sheet and a manufacturing method thereof. [Background technology]

[0002] With the rapid development of electric vehicles, higher requirements are being placed on non-oriented silicon steel as the magnetic core material of their core components (i.e., drive motors). Non-oriented silicon steel should have sufficiently high strength to withstand centrifugal forces at high rotational speeds while ensuring that the rotor is not deformed or destroyed. It should also have excellent electromagnetic properties, especially the lowest possible core loss and high magnetic induction strength in the high frequency range of 400 Hz to 2000 Hz, to meet the high torque requirements when the motor starts or accelerates.

[0003] Chinese Patent Application Publication No. 101490294 (published on July 22, 2009, entitled "High Strength Non-oriented Electrical Steel Sheet") discloses a non-oriented electrical steel sheet having a strength exceeding 650 MPa. Although this electrical steel sheet has high strength, it has a low iron loss P 10 / 400 is high at 70W / kg, and its electromagnetic properties are poor.

[0004] Chinese Patent Application Publication No. 112930412 (published June 8, 2021, entitled "Non-oriented electrical steel sheet and manufacturing method thereof, and motor core and manufacturing method thereof") discloses a non-oriented electrical steel sheet with excellent strength and iron loss. The main solution in Chinese Patent Application Publication No. 112930412 is to anneal a cold-rolled steel sheet with a silicon content of 2.8 to 6.5% at 700 to 820°C, strengthening it with an incompletely recrystallized structure with a recrystallized area ratio of 40 to 95%, resulting in a steel sheet with a yield strength of over 500 MPa. However, this method does not simultaneously address the high frequency and high magnetic flux intensity requirements of drive motors, resulting in low iron loss.

[0005] From the above, it is expected that a non-oriented electrical steel having high strength and excellent electromagnetic properties and excellent overall performance, and a method for manufacturing the same, can be obtained. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Chinese Patent Application Publication No. 101490294 [Patent Document 2] Chinese Patent Application Publication No. 112930412 Summary of the Invention

[0007] One objective of the present disclosure is to provide a non-oriented electrical steel with excellent overall performance, which has small magnetic anisotropy, high magnetic induction strength, small iron loss at medium and high frequencies, and high yield strength, and can be widely used as an iron core material for electric vehicle drive motors, high-speed motors, unmanned aerial vehicles, etc.

[0008] To achieve the above-mentioned objectives, the present disclosure provides a non-oriented electrical steel comprising, in addition to Fe and inevitable impurities, the following chemical elements in mass percentages: C≦0.0050%, Si: 3.10 to 4.50%, Al: 0.10 to 2.00%, Mn: 0.10 to 2.50%; and 3.75%≦Si+Al≦5.22%, preferably 3.75%≦Si+Al≦5.00%.

[0009] Preferably, the present disclosure provides a non-oriented electrical steel comprising the following chemical elements in mass percentages: C≦0.0050%, Si: 3.10 to 4.50%, Al: 0.10 to 2.00%, Mn: 0.10 to 2.50%, and the balance being Fe and unavoidable impurities; and 3.75%≦Si+Al≦5.22%, preferably 3.75%≦Si+Al≦5.00%.

[0010] In the non-oriented electrical steel according to the present disclosure, the design principles of each chemical element are as follows.

[0011] C: In the non-oriented electrical steel according to the present disclosure, C element is an impurity element that is harmful to the magnetic properties of the non-oriented silicon steel. Therefore, the content of C element should be controlled to C≦0.0050%, for example, C≦0.0042%, or C≦0.0030%.

[0012] Si: In the non-oriented electrical steel according to the present disclosure, Si increases resistivity and reduces iron loss in the non-oriented electrical steel sheet. It also acts as a solid-solution strengthening element to improve the strength of the steel sheet. If the Si content is higher than 4.50%, ordered phases such as Fe3Si and FeSi are formed, resulting in a rapid decrease in the room-temperature plasticity of the material, making industrial large-scale cold-rolling production impossible, and the magnetic induction strength is also reduced. If the Si content is less than 3.10%, the effects of high yield strength and low iron loss at high frequencies cannot be achieved. For these reasons, the Si content is controlled to 3.10 to 4.50%. For example, the upper limit of the Si content may be 4.00% or 3.78%, and the lower limit of the Si content may be 3.25%.

[0013] Al: In the non-oriented electrical steel according to the present disclosure, Al is also an effective element for increasing resistivity and reducing iron loss. However, excessive addition of Al is unfavorable for the magnetic induction strength of the material, causes difficulties in steelmaking and casting, and reduces the cold workability of the steel sheet. Therefore, the amount of Al added is controlled to 2.00% or less. At the same time, taking into account the iron loss improvement effect of this element, the amount added is controlled to 0.10% or more. For these reasons, the Al content is controlled to 0.10 to 2.00%. For example, the upper limit of the Al content may be 1.50% or 1.35%, and the lower limit of the Al content may be 0.15%, 0.50%, or 0.65%.

[0014] Furthermore, in this disclosure, the total content of the two alloying elements Si and Al is controlled to 3.75% to 5.22%, preferably 3.75% to 5.00%, because these two elements are both solid-solution strengthening elements and increase the resistivity of the material. If the total content is less than 3.75%, the performance of the non-oriented silicon steel sheet of this disclosure cannot be achieved. If the total content is higher than 5.22%, it will make cold-rolling production difficult and reduce magnetic induction. For example, the upper limit of the Si+Al content may be 5.00% or 4.80%, and the lower limit of the Si+Al content may be 3.95% or 4.10%.

[0015] Mn: In the non-oriented electrical steel according to the present disclosure, Mn improves resistivity and reacts with the impurity element S to form MnS, thereby improving electromagnetic properties. Therefore, the addition of 0.10% or more of Mn is necessary, but adding more than 2.50% of Mn reduces the plasticity of the steel and can cause the steel strip to break during cold rolling. Therefore, the Mn content is controlled to 0.10% to 2.50%, preferably 0.10 to 2.00%. For example, the upper limit of the Mn content may be 1.84% or 1.51%, and the lower limit of the Mn content may be 0.15%, 0.35%, or 0.65%.

[0016] Preferably, the content of the C element is C≦0.0030%.

[0017] Of the unavoidable impurities, the following are preferred: P≦0.040%, S≦0.0030%, N≦0.0050%, O≦0.0030%, and Nb+V+Ti≦0.0050%.

[0018] More preferably, among the unavoidable impurities, P≦0.020% and N≦0.0035%.

[0019] In the non-oriented electrical steel according to the present disclosure, the elements P, S, N, O, Nb, V, and Ti are all impurity elements. When technical conditions permit, the content of impurity elements in the steel should be reduced as much as possible to obtain steel with better performance and quality.

[0020] P: P is a grain boundary segregating element. In the composition system having a Si content greater than 3.10% according to the present disclosure, if the P content is higher than 0.040%, the brittleness of the electrical steel sheet worsens, making rolling difficult. For example, the P content may be P≦0.034%, P≦0.024%, or P≦0.020%.

[0021] S: In this disclosure, S is an element that is detrimental to magnetic properties. It combines with Mn to form fine MnS, which inhibits grain growth during annealing of the finished product and reduces the magnetic properties of the steel sheet. Therefore, the content of S element is controlled to S≦0.0030% by mass. For example, S≦0.0018% or S≦0.0015%.

[0022] N: In the present disclosure, N is an element that is detrimental to magnetic properties. It combines with Al, Ti, Nb, and V to form fine nitrides, thereby hindering grain growth. Therefore, in the non-oriented electrical steel according to the present disclosure, the content of N element is controlled to N≦0.0050% by mass. For example, N≦0.0035% or N≦0.0015%.

[0023] O: In the present disclosure, O is a harmful element. In the composition system where 3.75%≦Si+Al≦5.22%, the cold workability of the material is very sensitive to oxygen segregation at the grain boundaries, and the formed oxides of silicon, aluminum, and manganese can also deteriorate the magnetic properties of the material. Therefore, in the present disclosure, the content of O element is controlled to O≦0.0030%, for example, O≦0.0021%, or O≦0.0015%, by mass percentage.

[0024] Nb, V, and Ti can combine with residual C and N in the steel to form fine carbides and nitrides, which seriously affect grain growth during annealing and are unfavorable for the magnetic properties of the material. Therefore, in the present disclosure, the total content of the three elements Nb, V, and Ti is controlled to 0.0050% or less, for example, 0.0045% or less, or 0.0035% or less, by mass percentage.

[0025] Preferably, the non-oriented electrical steel according to the present disclosure further contains B: 0.0003 to 0.0100%.

[0026] In the above technical solution of the present disclosure, in order to further optimize the performance of the non-oriented electrical steel of the present disclosure, preferably, an appropriate amount of B element can be added to the steel.

[0027] B: In the non-oriented electrical steel according to the present disclosure, B is a grain boundary strengthening element. This can improve the cold rolling processability of the material by enhancing the grain boundary bonding ability of high silicon composition systems. However, adding an excessive amount of B element refines the crystal grain structure, which does not contribute to magnetic properties. Therefore, the B content should be 0.0100% or less by mass percentage. If the B element content in the steel is less than 0.0003%, the grain boundary strengthening effect cannot be obtained. For example, the upper limit of the B content may be 0.0080%, and the lower limit of the B content may be 0.0010%.

[0028] Preferably, the non-oriented electrical steel according to the present disclosure contains at least one selected from Sn and Sb, and the total content of Sn and Sb is 0.005 to 0.300%. For example, the total content of Sn and Sb may be 0.010 to 0.300%.

[0029] Both Sn and Sb are grain boundary segregating elements. On the one hand, Sn and Sb can prevent the diffusion of trace oxygen along grain boundaries during the normalizing annealing process of hot-rolled steel sheets, thereby preventing oxidation and a decrease in plasticity of the steel sheets. On the other hand, Sn and Sb can improve textures, such as the {100} plane texture and Goss texture, which are beneficial to magnetic properties, during the annealing process of the finished sheets.

[0030] Preferably, the non-oriented electrical steel according to the present disclosure further contains at least one element selected from Co, Ni, Cu, and Cr, and the total content of these elements is controlled to be 0.02 to 3.00% by mass. For example, the total content of Co, Ni, Cu, and Cr may be 0.30 to 3.00%, e.g., 0.40 to 2.00%.

[0031] Co, Ni, Cu and Cr elements can have the effect of solid solution strengthening, which can further improve the electromagnetic properties and strength of the material without impairing the cold workability of the steel sheet.

[0032] Preferably, the non-oriented electrical steel according to the present disclosure has an average grain size of 10 to 110 μm, preferably 35 to 98 μm.

[0033] If the grain size of the finished plate is less than 10 μm, the iron loss P 10 / 600 The performance requirements of this disclosure cannot be met. If the grain size of the finished plate exceeds 110 μm, the yield strength will decrease, production efficiency will be low, the requirements for production equipment will be high, and costs will increase.

[0034] Preferably, the non-oriented electrical steel according to the present disclosure has a thickness of 0.10 to 0.30 mm, for example 0.15 to 0.30 mm.

[0035] The non-oriented electrical steel according to the present disclosure has excellent overall performance including high strength, low core loss, high magnetic induction, and low magnetic anisotropy.

[0036] Preferably, the non-oriented electrical steel according to the present disclosure has a yield strength of ≧430 MPa, preferably ≧455 MPa.

[0037] Preferably, the non-oriented electrical steel according to the present disclosure has an iron loss P of ≦35.0 W / kg at a magnetic flux density of 1.0 T and a frequency of 600 Hz. 10 / 600 (Preferably P 10 / 600 ≦29.3W / kg), magnetic induction strength B ≧1.640T 50 (Preferably B 50 ≧1.654T) and has a longitudinal magnetic induction strength B 50L and the transverse magnetic induction strength B 50C The difference ΔB between the two is 1000 gauss or less (preferably ΔB is 822 gauss or less).

[0038] Accordingly, another object of the present disclosure is to provide a method for producing the above-mentioned non-oriented electrical steel, which is simple and feasible, and by which a non-oriented electrical steel sheet with excellent overall performance can be obtained.

[0039] In order to achieve the above-mentioned object, the present disclosure provides a method for producing a non-oriented electrical steel, the method comprising the steps of: (1) Cast slab production; (2) Hot rolling: The reduction ratio of the final pass in rough rolling is controlled to 35-55%, and the intermediate slab obtained from rough rolling is kept warm for 50-80 seconds before entering the finishing mill. The temperature of the intermediate slab when entering the finishing mill is 960-1100°C (preferably 965-1100°C), and the temperature difference (ΔT) between the front end and the rear end of the intermediate slab is ≦40°C (preferably ≦35°C); (3) Normalizing annealing; (4) cold rolling; (5) Final annealing; (6) Application of insulating coating.

[0040] Preferably, in step (2), the {111} <112> The ratio I of the {001} plane texture intensity to the texture intensity is ≧0.55.

[0041] In this disclosure, the inventors optimize the chemical composition design of steel and determine a rational manufacturing process, in which a continuously cast slab is produced according to the designed chemical composition, and then the continuously cast slab is sequentially subjected to hot rolling, normalizing annealing, cold rolling (which can be one-pass cold rolling or two-pass cold rolling with intermediate annealing), final annealing, and application of an insulating coating to obtain a non-oriented electrical steel with excellent overall performance.

[0042] Preferably, during hot rough rolling of the continuously cast slab, the reduction ratio of the final pass is controlled to 35-55% to obtain an intermediate slab. Before entering the hot finishing mill, the intermediate slab must remain on a roller table equipped with a heat-insulating cover for 50-80 seconds, or it can be recoiled and uncoiled using a hot coil box facility after the roughing mill to achieve a heat-insulating holding time of 50-80 seconds. The temperature of the intermediate slab when it enters the first stand of the finishing mill is controlled to 960-1100°C, and the temperature difference ΔT between the front and rear ends of the intermediate slab is ≦40°C.

[0043] The above process parameters mainly allow the intermediate slab to be fully recrystallized, reduce the solid solution precipitation of second phases such as AlN, MnS and TiC, and increase the texture beneficial to the magnetic properties. In particular, the {001} plane texture intensity at the position located at a distance of one-quarter of the slab thickness from the intermediate slab surface is increased, and the {111} plane texture intensity is increased. <112> The ratio of the annealed steel sheet to the longitudinal magnetic induction strength is controlled to be ≥ 0.55, thereby improving the texture of the finished annealed steel sheet, reducing the magnetic anisotropy, and increasing the longitudinal magnetic induction strength B. 50L and the transverse magnetic induction strength B 50C The difference ΔB between the magnetic induction intensity B and the 50A technical effect of more than 1.64T is achieved.

[0044] In addition, the temperature difference ΔT between the leading and trailing ends of the intermediate slab is controlled to be ≦40°C, which ensures the consistency of performance across the entire coil of steel strip products and achieves constant speed, isothermal rolling in the subsequent finishing mill, significantly reducing the risk of motor overcurrent when producing thin high-grade non-oriented silicon steel sheets through the finishing mill and thereby ensuring the stability of continuous production.

[0045] Preferably, in step (2), the thickness of the intermediate slab obtained by rough rolling is 25 to 40 mm.

[0046] Preferably, in step (3), the normalizing temperature is 850 to 1050°C, and the normalizing holding time is, for example, 90 seconds.

[0047] Preferably, in step (5), the final annealing temperature is 750 to 1000°C and the final annealing time is 11 to 125 seconds.

[0048] The final annealing process is intended to better achieve the target grain size of 10-110 μm in the finished non-oriented electrical steel sheet. If the annealing temperature is too low or the annealing time is too short, the grain size of the finished sheet will be less than 10 μm, resulting in a decrease in iron loss P. 10 / 600 If the annealing temperature is too high or the annealing time is too long, the grain size of the finished steel sheet will exceed 110 μm, resulting in reduced yield strength, lower production efficiency, and increased costs.

[0049] The non-oriented electrical steel and its manufacturing method described in this disclosure have the following advantages and beneficial effects: The non-oriented electrical steel according to the present disclosure has small magnetic anisotropy, high magnetic induction strength, small iron loss at medium and high frequencies, and high yield strength, and can be widely used as an iron core material for drive motors of electric vehicles, high-speed motors, unmanned aerial vehicles, etc.

[0050] Preferably, the non-oriented electrical steel according to the present disclosure has a yield strength of ≧430 MPa (preferably ≧455 MPa), an iron loss P 10 / 600 ≦35.0W / kg (preferably P 10 / 600 ≦29.3W / kg), magnetic induction strength B 50 ≧1.640T (preferably B 50 ≥ 1.654 T), and a longitudinal magnetic induction strength B of ≤ 1000 Gauss 50L and the transverse magnetic induction strength B 50C and ΔB (preferably ΔB is ≦822 Gauss).

[0051] Unless expressly stated otherwise or where there is a clear contradiction, the endpoints of the ranges set forth herein may be combined in any way to create additional ranges or subranges. For example, in some embodiments, the upper limit value stated for a certain feature may be used as the lower limit value for that feature, and vice versa. DETAILED DESCRIPTION OF THE INVENTION

[0052] The non-oriented electrical steel and its manufacturing method according to the present disclosure will be further described and illustrated below with reference to specific embodiments, however, these descriptions and illustrations do not constitute undue limitations on the technical solutions of the present disclosure.

[0053] Examples 1 to 10 and Comparative Examples 1 to 5 Table 1 lists the mass percentages of each chemical element in the finished electrical steels of Examples 1-10 and Comparative Examples 1-5.

[0054] [Table 1]

[0055] The non-oriented electrical steels of Examples 1 to 10 were prepared by the following steps. (1) Smelting and casting of molten steel were carried out to obtain cast slabs.

[0056] (2) Hot rolling (including rough rolling and finish rolling): The reduction ratio of the final pass in rough rolling was controlled to 35-55% to obtain an intermediate slab with a thickness of 25-40 mm; the intermediate slab was clamped and kept warm for 50-80 seconds before entering the finish rolling mill; <112> The ratio I of the {001} plane texture intensity to the texture intensity was ≥ 0.55 at a position a quarter of the slab thickness from the slab surface before entering the finishing mill; the temperature of the intermediate slab was 960–1100°C when entering the finishing mill, and the temperature difference ΔT between the front and rear ends of the intermediate slab was controlled to be ≤ 40°C.

[0057] (3) Normalizing annealing: The normalizing temperature in Examples 1 to 4 was 1050°C, the normalizing temperature in Examples 5 to 7 was 920°C, and the normalizing temperature in Examples 8 to 10 was 850°C; the normalizing temperature in Comparative Examples 1 to 5 was 920°C; the normalizing holding time in Examples 1 to 10 and Comparative Examples 1 to 5 was 90 seconds.

[0058] (4) Cold rolling: Rolling to the target thickness by a single cold rolling, or rolling to a plate with a thickness of 0.10 to 0.30 mm by a first cold rolling + intermediate annealing + second cold rolling.

[0059] (5) Final annealing: The final annealing temperature was 750 to 1000°C, and the final holding time was 11 to 125 seconds.

[0060] (6) Apply insulating coating.

[0061] It should be noted that Comparative Examples 1-5 were also prepared using the above processing steps, but one or more of their specific process parameters and / or chemical element contents do not meet the control requirements of the present disclosure.

[0062] Table 2 lists the specific manufacturing process parameters and final finished product thicknesses of the electrical steels of Examples 1 to 10 and Comparative Examples 1 to 5.

[0063] [Table 2]

[0064] The finally obtained finished electrical steels of Examples 1 to 10 and Comparative Examples 1 to 5 were sampled, and the iron loss P 10 / 600 , magnetic induction strength B when magnetized under a magnetic field of 5000 A / m 50 , longitudinal magnetic induction strength B 50L and transverse magnetic induction strength B 50C The test results are listed in Table 3 below. The test methods for the relevant performance are described below.

[0065] The grain size of the finished plate is measured based on the area method of the standard "GB / T6394-2017 Method for Determining the Average Grain Size of Metals."

[0066] Iron loss P 10 / 600 The test is based on the Epstein method of the standard "GB / T10129-2019 Method for determining medium-frequency magnetic properties of electrical steel strips (pieces)."

[0067] The magnetic induction strength is measured based on the Epstein method of the standard "GB / T3655-2008 Method for measuring the magnetic properties of electromagnetic steel pieces (strips) using an Epstein tester" and B 50 , vertical direction B 50L , and the horizontal direction B 50C are tested respectively.

[0068] The yield strength performance index is measured based on the standard "GB / T228.1-2010 Metallic Materials Tensile Test Part 1: Room Temperature Test Method."

[0069] Table 3 lists the test results of the finished electrical steels of Examples 1 to 10 and Comparative Examples 1 to 5.

[0070] [Table 3]

[0071] According to Tables 1, 2, and 3, in Comparative Examples 1 and 2, the Si content is not within the range of the present disclosure. As a result, the grain size of the finished product of Comparative Example 1 exceeds the upper limit, the yield strength is low, and the iron loss of Comparative Example 2 is large.

[0072] The Si content of Comparative Example 3 does not meet the requirements of the present disclosure, with the Si+Al content being less than 3.75%, which results in low yield strength. Although the compositions of Comparative Examples 4 and 5 meet the requirements of the present disclosure, the hot rolling process parameters and texture ratio I are not within the specified ranges, so Comparative Examples 4 and 5 cannot achieve the desired magnetic induction strength and magnetic anisotropy of the finished product of the present disclosure.

[0073] In Examples 1 and 2 of the present disclosure, a single-pass cold rolling process is adopted, and the chemical composition, the reduction rate of the final rough rolling, the heat retention time, the temperature of the intermediate slab when it enters the finishing mill, the temperature difference between the front and rear ends of the intermediate slab, and the grain size of the finished product are all within the design ranges of the present disclosure, so that a non-oriented silicon steel with excellent overall performance, such as high yield strength and excellent magnetic properties, can be obtained.

[0074] In Example 2 of the present disclosure, Sn and Sb are further added, and the strength and core loss are better than those of Example 1.

[0075] In Example 3 of the present disclosure, B is further added, and the strength and core loss are better than those of Example 1.

[0076] In Examples 4 to 9 of the present disclosure, the performance of the finished steel sheet is further improved by further adding at least one selected from trace alloy elements Sn, Sb, Co, Ni, Cu, and Cr and by using a double cold rolling process.

[0077] In Example 10 of the present disclosure, trace alloy elements such as Co, Ni, Cu, and Cr are further added, and the strength and core loss are better than those of Example 1.

[0078] It should be noted that the prior art part within the protection scope of the present disclosure is not limited to the embodiments described in the application documents, and all prior art that is not inconsistent with the solution of the present disclosure, including, but not limited to, prior patent documents, prior publications, and prior public use, may be included in the protection scope of the present disclosure.

[0079] Furthermore, the combinations of the technical features of the present disclosure are not limited to the combinations described in the claims or the specific embodiments of the present disclosure, and all technical features described in the present disclosure can be freely combined in any manner as long as they are not mutually contradictory.

[0080] It should be further noted that the above exemplified embodiments are merely specific examples of the present disclosure. It is clear that the present disclosure is not limited to the above-described embodiments and may undergo various changes or modifications. Those skilled in the art may directly obtain or easily conceive such changes or modifications from the disclosure of the present disclosure, and they all fall within the protection scope of the present disclosure.

Claims

1. A non-oriented electrical steel containing, in addition to Fe and unavoidable impurities, the following chemical elements in mass percentages: C≦0.0050%, Si: 3.10 to 4.50%, Al: 0.10 to 2.00%, Mn: 0.10 to 2.50%; and 3.75%≦Si+Al≦5.22%, preferably 3.75%≦Si+Al≦5.00%.

2. 2. The non-oriented electrical steel according to claim 1, comprising the following chemical elements in mass percentages: C≦0.0050%, Si: 3.10 to 4.50%, Al: 0.10 to 2.00%, Mn: 0.10 to 2.50%, and the balance being Fe and unavoidable impurities; and 3.75%≦Si+Al≦5.22%, preferably 3.75%≦Si+Al≦5.00%.

3. The non-oriented electrical steel according to claim 1 or 2, wherein C≦0.0030%.

4. 3. The non-oriented electrical steel according to claim 1, wherein the unavoidable impurities are P≦0.040%, S≦0.0030%, N≦0.0050%, O≦0.0030%, and Nb+V+Ti≦0.0050%.

5. 5. The non-oriented electrical steel according to claim 4, wherein P≦0.020% and N≦0.0035%.

6. The non-oriented electrical steel according to claim 1 or 2, further comprising B: 0.0003 to 0.0100%.

7. 3. The non-oriented electrical steel according to claim 1, further comprising at least one selected from Sn and Sb, wherein the total content of Sn and Sb is, in mass percentage, 0.005 to 0.300%.

8. 3. The non-oriented electrical steel according to claim 1 or claim 2, further comprising at least one selected from Co, Ni, Cu, and Cr, wherein the total content of Co, Ni, Cu, and Cr is, in mass percentage, 0.02 to 3.00%, preferably 0.30 to 3.00%.

9. 3. The non-oriented electrical steel according to claim 1, having an average grain size of 10 to 110 μm.

10. 3. The non-oriented electrical steel according to claim 1, having a thickness of 0.10 to 0.30 mm.

11. Yield strength ≧430 MPa, iron loss P ≦35.0 W / kg １０／６００ , magnetic induction strength B ≥ 1.640 T ５０ , and a longitudinal magnetic induction strength B of 1000 Gauss or less ５０Ｌ and the transverse magnetic induction strength B ５０Ｃ The non-oriented electrical steel according to claim 1 or 2, wherein the difference ΔB between the

12. A method for producing a non-oriented electrical steel according to any one of claims 1 to 11, comprising the following steps: (1) Production of cast slabs; (2) Hot rolling: the reduction rate of the final pass in rough rolling is 35-55%, and the intermediate slab obtained from rough rolling is kept warm for 50-80 seconds before entering the finishing mill, and the temperature of the intermediate slab when entering the finishing mill is 960-1100°C, and the temperature difference (ΔT) between the front end and the rear end of the intermediate slab is ≦40°C; (3) Normalizing annealing; (4) cold rolling; (5) Final annealing; (6) Application of insulating coating.

13. 13. The method of claim 12, wherein in step (2), a ratio I of {001} plane texture intensity to {111}<112> texture intensity is ≥ 0.55 at a position in the intermediate slab prior to entry into the finish rolling mill that is a quarter of the slab thickness from the slab surface.

14. The method according to claim 12, wherein in step (2), the intermediate slab obtained by the rough rolling has a thickness of 25 to 40 mm.

15. The method according to claim 12, wherein in step (3), the normalizing is carried out at a temperature of 850 to 1050°C.

16. 13. The method according to claim 12, wherein in step (5), the final annealing is carried out at a temperature of 750 to 1000°C for 11 to 125 seconds.

Images