Non-oriented electrical steel sheet and method for manufacturing same

Abstract

The present application relates to a non-oriented electrical steel sheet and a method for manufacturing same. According to the non-oriented electrical steel sheet and the method for manufacturing same of the present application, the non-oriented electrical steel sheet can possess excellent magnetic properties through texture improvement.

Description

Non-oriented electrical steel sheet and manufacturing method thereof

[0001] This application relates to a non-oriented electrical steel sheet and a method for manufacturing the same.

[0002] Due to recent policies to reduce CO2 emissions to combat global warming, conventional internal combustion engine vehicles are rapidly being replaced by eco-friendly vehicles such as hybrid electric vehicles (HEVs) and, especially, electric vehicles (EVs). These EVs require high torque at low speeds and during acceleration, and high-speed rotation at speeds exceeding 200 Hz at constant and high speeds. Consequently, the non-oriented electrical steel used as the core material for the motor must simultaneously meet high magnetic flux density and low core loss.

[0003] Factors affecting the magnetic properties of non-oriented electrical steel sheets include chemical composition, thickness, microstructure, insulating coating layer, and / or texture. These various factors are influenced by the manufacturing process conditions for non-oriented electrical steel sheets. Typically, non-oriented electrical steel sheets are manufactured through a series of processes including steelmaking / casting, hot rolling, preliminary annealing, cold rolling, final annealing, and coating. Optimizing each process condition can yield superior magnetic properties.

[0004] Among these, the aggregate structure is one of the important factors for improving iron loss and magnetic flux density. In terms of aggregate structure, <100> The direction is one that is easy to magnetize, <111> A direction is the unfavorable magnetization direction. Magnetization is determined by the processes of domain wall motion and domain rotation. The more favorable orientations there are in a sample and the fewer unfavorable orientations there are, the higher the magnetic flux density and the lower the iron loss. Due to this crystalline magnetic anisotropy, the magnetic flux density and iron loss in non-oriented electrical steel sheets are highly dependent on the grain structure.

[0005] Patent Document 1 (Japanese Patent Application Publication No. 2016-199787) proposes a method for securing superior magnetic properties by improving the grain structure of a non-oriented electrical steel sheet by heating it at a heating rate of 100°C / s or higher between 630°C and 700°C during the final annealing process. However, Patent Document 1 suffers from the problem that, despite the improved grain structure, the rapid heating during the final annealing process also reduces the grain size, resulting in increased iron loss. Therefore, a non-oriented electrical steel sheet and a manufacturing method thereof that can address these issues are in demand.

[0006] The object of the present application is to provide a non-oriented electrical steel sheet with excellent magnetic properties by improving the aggregate structure and a method for manufacturing the same.

[0007] In order to solve the above problem, the non-oriented electrical steel sheet of the present application contains, in wt%, Si: 1.8% or more and 3.8% or less, Mn: 0.2% or more and 0.4% or less, Al: 0.8% or more and 1.5% or less, B: more than 0% and less than 0.02%, and Ce: more than 0% and less than 0.02%, and the remainder includes Fe and inevitable impurities, and satisfies the following general formula 1.

[0008] [General Formula 1]

[0009]

[0010] In the general formula 1 above, a is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45° max ), and b is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, and φ2=45° max), and c is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45° max )am.

[0011] In the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g)) max ) can be 4.4 or more and 7.0 or less.

[0012] In addition, in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g) max ) has a direction (g) of {113} <251> It could be defense.

[0013] In addition, in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, φ2=45°, the maximum intensity of the orientation distribution function (f(g) max ) can be 3.0 or more and 7.0 or less.

[0014] In addition, in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, φ2=45°, the maximum intensity of the orientation distribution function (f(g) max ) has a direction (g) of {100} <130> It could be defense.

[0015] In addition, in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g) max ) can be 3.0 or more and 8.5 or less.

[0016] In addition, in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g) max ) has a direction (g) of {334} <483> It could be defense.

[0017] In addition, the non-oriented electrical steel sheet may have a total weight % of B and Ce of more than 0% and less than or equal to 0.02%.

[0018] In addition, the non-oriented electrical steel sheet may further include, in weight %, at least one selected from C: more than 0% and 0.002% or less, P: more than 0% and 0.015% or less, S: more than 0% and 0.002% or less, N: more than 0% and 0.002% or less, and Ti: more than 0% and 0.002% or less.

[0019] In addition, the non-oriented electrical steel sheet has iron loss W measured at angles of 0° and 90° with respect to the rolling direction during cold rolling. 10 / 400 The average is less than 13.00 W / kg, and the magnetic flux density (B 50 ) may have an average of 1.64 T or more.

[0020] In addition, the method for manufacturing a non-oriented electrical steel sheet of the present application includes a step of reheating and then hot-rolling a slab containing, in wt%, Si: 1.8% or more and 3.8% or less, Mn: 0.2% or more and 0.4% or less, Al: 0.8% or more and 1.5% or less, B: more than 0% and less than 0.02%, and Ce: more than 0% and less than 0.02%, and the remaining Fe and unavoidable impurities; a step of cold-rolling to manufacture a cold-rolled steel sheet; and a step of finally annealing the cold-rolled steel sheet, wherein the finally annealed steel sheet satisfies the following general formula 1.

[0021] [General Formula 1]

[0022]

[0023] In the general formula 1 above, a is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45° max ), and b is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, and φ2=45° max ), and c is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45° max )am.

[0024] In addition, in the final annealed steel plate, the maximum intensity (f(g)) of the orientation distribution function in the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45° max ) can be 4.4 or more and 7.0 or less.

[0025] In addition, in the final annealed steel plate, the maximum intensity (f(g)) of the orientation distribution function in the texture appearing at the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, φ2=45° max ) can be 3.0 or more and 7.0 or less.

[0026] In addition, in the final annealed steel plate, the maximum intensity (f(g)) of the orientation distribution function in the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45° max ) can be 3.0 or more and 8.5 or less.

[0027] Additionally, the slab may have a total weight % of B and Ce of greater than 0% and less than or equal to 0.02%.

[0028] In addition, the slab may further include, in wt%, at least one selected from C: more than 0% and less than or equal to 0.002%, P: more than 0% and less than or equal to 0.015%, S: more than 0% and less than or equal to 0.002%, N: more than 0% and less than or equal to 0.002%, and Ti: more than 0% and less than or equal to 0.002%.

[0029] In addition, the method for manufacturing the non-oriented electrical steel sheet further includes a step of pre-annealing the hot-rolled steel sheet after the hot-rolling step, and the pre-annealing step can be performed by heating the hot-rolled steel sheet to 900°C or higher and 1100°C or lower at a heating rate of 20°C / s or higher.

[0030] In addition, the above hot-rolled steel sheet may have an average grain size of 100 ㎛ or more and 250 ㎛ or less during the preliminary annealing process.

[0031] According to the non-oriented electrical steel sheet of the present application and the method for manufacturing the same, excellent magnetic properties can be obtained by improving the texture.

[0032] The present application relates to a non-oriented electrical steel sheet, which is a core material used in a motor that converts electrical energy into mechanical energy. The non-oriented electrical steel sheet contains, in wt%, Si: 1.8% or more and 3.8% or less, Mn: 0.2% or more and 0.4% or less, Al: 0.8% or more and 1.5% or less, B: 0% or more and less than 0.02%, and Ce: 0% or more and less than 0.02%, and the remainder includes iron and inevitable impurities, and satisfies the following general formula 1.

[0033] [General Formula 1]

[0034]

[0035] In the general formula 1 above, a is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45° max), and b is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, and φ2=45° max ), and c is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45° max )am.

[0036] Specifically, the value calculated by the general formula 1 above may be 5.2 or more or 5.4 or more. In addition, the upper limit of the value calculated by the general formula 1 above may be 15 or less, 14 or less or 13 or less. The non-oriented electrical steel sheet may have excellent magnetic properties, specifically, low iron loss and high magnetic flux density, by satisfying the general formula 1 described above. At this time, the intensity (f(g)) of the orientation distribution function means the relative intensity when the intensity 1 of a disordered structure having no aggregate structure is used as a standard. For example, the maximum intensity (f(g)) of the orientation distribution function max ) means the maximum intensity among the intensities of the orientations of the aggregate tissue existing in the angle range of φ1 and the angle range of Φ shown in the cross-section of the orientation distribution function (ODF) with φ2=45°.

[0037] In one example, in the set of structures appearing at Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g) max ) can be 4.4 or more and 7.0 or less. Specifically, in the set structure appearing in the Euler angles mentioned above, the maximum intensity of the orientation distribution function (f(g) max) may be 4.4 or more and 6.8 or less, 4.4 or more and 6.5 or less, or 4.4 or more and 6.3 or less. The non-oriented electrical steel sheet satisfies the general formula 1, and in the aggregate structure appearing at the aforementioned Euler angle, the maximum intensity of the orientation distribution function (f(g) max ) can have excellent magnetic properties, specifically, high magnetic flux density and low iron loss, by satisfying the aforementioned range.

[0038] For example, in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g) max ) has a direction (g) of {113} <251> It could be a defense. That is, the above {113} <251> The orientation is a favorable orientation for magnetization, and the maximum intensity (f(g)) of the orientation distribution function described above for the non-oriented electrical steel sheet max ), the non-oriented electrical steel sheet can have excellent magnetic properties, specifically, high magnetic flux density and low iron loss.

[0039] In addition, in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, φ2=45°, the maximum intensity of the orientation distribution function (f(g) max ) can be 3.0 or more and 7.0 or less. Specifically, in the set structure appearing in the Euler angles mentioned above, the maximum intensity of the orientation distribution function (f(g) max ) may be 3.1 or more and 6.7 or less or 3.2 or more and 6.5 or less. The non-oriented electrical steel sheet satisfies the general formula 1, and in the aggregate structure appearing at the aforementioned Euler angle, the maximum intensity of the orientation distribution function (f(g) max ) can have excellent magnetic properties, specifically, high magnetic flux density and low iron loss, by satisfying the aforementioned range.

[0040] For example, in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g) max ) has a direction (g) of {100} <130> It can be a defense. That is, the above {100} <130> The orientation is a favorable orientation for magnetization, and the maximum intensity (f(g)) of the orientation distribution function described above for the non-oriented electrical steel sheet max ), the non-oriented electrical steel sheet can have excellent magnetic properties, specifically, high magnetic flux density and low iron loss.

[0041] In addition, in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g) max ) can be 3.0 or more and 8.5 or less. Specifically, in the set structure appearing in the Euler angles mentioned above, the maximum intensity of the orientation distribution function (f(g) max ) may be 3.2 or more and 8.4 or less, 3.5 or more and 8.3 or less, or 3.7 or more and 8.2 or less. The non-oriented electrical steel sheet satisfies the general formula 1, and in the aggregate structure appearing at the Euler angles described above, the maximum intensity of the orientation distribution function (f(g) max ) can have excellent magnetic properties, specifically, high magnetic flux density and low iron loss, by satisfying the aforementioned range.

[0042] For example, in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g) max ) has a direction (g) of {334} <483> It could be a defense. That is, the above {334} <483> The orientation is an orientation unfavorable to magnetization, and the maximum intensity (f(g)) of the orientation distribution function described above for the non-oriented electrical steel sheetmax ), the non-oriented electrical steel sheet can have excellent magnetic properties, specifically, high magnetic flux density and low iron loss.

[0043] In one example, the non-oriented electrical steel sheet has iron loss W measured at angles of 0° and 90° with respect to the rolling direction during cold rolling. 10 / 400 The average may be less than 13.00 W / kg, and the magnetic flux density (B 50 ) may be greater than 1.64 T. Specifically, the iron loss W measured under the conditions described above 10 / 400 The average of may be 12.80 W / kg or less or 12.60 W / kg or less. The above non-oriented electrical steel sheet has a core loss W 10 / 400 The lower the magnetic flux density (B), the better the magnetic properties are, and the lower limit is not particularly limited. 50 ) is not particularly limited in terms of the magnetic properties being better the higher it is, but for example, it can be 5 W / kg or more and 1.70 T or less, respectively. The iron loss W 10 / 400 It means the iron loss when a magnetic flux density of 1.0 T is induced at a high frequency of 400 Hz. In addition, the magnetic flux density (B 50 ) means the magnetic flux density induced in a magnetic field of 5000 A / m. At this time, the iron loss and the magnetic flux density were measured using a single sheet tester after punching the non-oriented electrical steel plate to a width of 60 mm × length of 60 mm.

[0044] The above non-oriented electrical steel sheet may have a thickness of less than 0.35 mm, and specifically, may have a thickness of 0.1 mm or more and less than 0.35 mm or 0.1 mm or more and 0.3 mm or less. Since the above non-oriented electrical steel sheet has a thickness within the above-mentioned range, eddy current loss is reduced, and thus excellent core loss can be achieved.

[0045] In one example, the non-oriented electrical steel sheet may further include a coating layer on the surface. The coating layer is an insulating coating layer formed on the surface of the non-oriented electrical steel sheet and may be referred to as an insulating film. Since the insulating film is widely known, a detailed description thereof will be omitted. For example, the coating layer may be formed by applying a chromate-based coating solution, or a chromium-free coating solution, which is an organic-inorganic composite coating solution that does not contain chromium, to the surface of a final annealed steel sheet, and then baking it. At this time, the thickness of the coating layer may be 0.1 ㎛ or more and 5 ㎛ or less. The non-oriented electrical steel sheet further includes the aforementioned coating layer on the surface, thereby maintaining insulation between upper and lower non-oriented electrical steel sheets when a plurality of non-oriented electrical steel sheets are stacked, thereby reducing eddy current loss.

[0046] The components of the above non-oriented electrical steel sheet are described below.

[0047] Si: 1.8 wt% or more and 3.8 wt% or less

[0048] Silicon (Si) is an element that increases the resistivity of a material and reduces eddy current loss. If the silicon is included in the non-oriented electrical steel sheet in an amount less than the lower limit of the aforementioned range, the iron loss reduction effect may be insufficient. In addition, if the silicon is included in the non-oriented electrical steel sheet in an amount greater than the upper limit of the aforementioned range, the magnetic permeability and magnetic flux density may decrease. On the other hand, since the silicon is included in the non-oriented electrical steel sheet in an amount of 1.8 wt% or more and 3.8 wt% or less, the texture can be improved even when a low content of silicon is added, and thus, a low iron loss value similar to the iron loss value that can be obtained when a high content of silicon is added can be obtained. Specifically, the silicon may be included in the non-oriented electrical steel sheet in an amount of 2.4 wt% or more and 3.5 wt% or less, or 3.0 wt% or more and 3.3 wt% or less.

[0049] Mn: 0.2 wt% or more and 0.4 wt% or less

[0050] Manganese (Mn) is an element that, together with Si, increases resistivity, lowers iron loss, and improves grain structure. When the manganese is included in the non-oriented electrical steel sheet in an amount less than the lower limit of the aforementioned range, fine MnS may precipitate, inhibiting grain growth and increasing iron loss. In addition, when the manganese is included in the non-oriented electrical steel sheet in an amount greater than the upper limit of the aforementioned range, coarse MnS may precipitate, reducing magnetic flux density, and reducing iron loss compared to the amount added, which may result in deterioration of cold rolling properties. Therefore, the manganese may be included in the non-oriented electrical steel sheet in an amount of 0.2 wt% or more and 0.4 wt% or less, and specifically, may be included in an amount of 0.2 wt% or more and 0.3 wt% or less.

[0051] Al: 0.8 wt% or more and 1.5 wt% or less

[0052] Aluminum (Al) is an element that increases resistivity together with the Si, thereby reducing eddy current loss, and induces precipitation of AlN when combined with nitrogen (N). If the aluminum is included in the non-oriented electrical steel sheet in an amount less than the lower limit of the aforementioned range, the resistivity may be insufficient, thereby increasing iron loss. In addition, if the aluminum is included in the non-oriented electrical steel sheet in an amount exceeding the upper limit of the aforementioned range, cold rolling properties may deteriorate and magnetic flux density may decrease. Therefore, the aluminum may be included in the non-oriented electrical steel sheet in an amount of 0.8 wt% or more and 1.5 wt% or less, and specifically, in an amount of 0.9 wt% or more and 1.0 wt% or less.

[0053] B: More than 0 wt% and less than 0.02 wt%

[0054] Boron (B) is an element that lowers grain boundary energy due to grain boundary segregation, and reduces the volume fraction of orientations that are unfavorable for magnetic properties by suppressing nucleation in {111} and {112} orientations as the recrystallization rate decreases, and increases {100} orientation and Goss orientation that are favorable for magnetism. Specifically, the boron is an element that lowers the elastic energy within the lattice by segregating to reduce the strain (E) caused by the lattice contraction due to C and / or N, which are solid-solution elements in the lattice, or by the lattice expansion by atoms such as interstitial elements, and by the expanded lattice. The boron segregates to lower the energy of grain boundaries with high interfacial energy through recrystallization and create a stable state. The orientations that are favorable for nucleation may be the {111} and {112} orientations. If the interfacial energy is lowered due to segregation, the possibility of nucleation in {111} and {112} orientations decreases, and the possibility of nucleation in other orientations increases, so that the nucleation in {111} and {112} orientations may be relatively suppressed. In addition, shear deformation rather than plane deformation may be applied to the material during rolling due to segregation, and while {111} and {112} orientations generally grow preferentially during recrystallization in a plane-deformed structure, nucleation in {110} orientation or other orientations rather than {111} and {112} orientations occurs preferentially during recrystallization in a shear-deformed structure. Therefore, the nucleation in {111} and {112} orientations may be suppressed by the shear deformation induced during rolling due to segregation. If the boron is contained in the non-oriented electrical steel sheet in an amount exceeding the upper limit of the aforementioned range, the boron hinders the growth of recrystallized grains due to the pinning effect caused by grain boundary segregation, thereby preventing grain growth and rather having a negative effect on the texture. Therefore, the boron may be contained in the non-oriented electrical steel sheet in an amount of more than 0 wt% and less than 0.02 wt%, and specifically, in an amount of 0.001 wt% or more and 0.016 wt% or less, or 0.002 wt% or more and 0.It may be included in amounts up to 0.12 wt%.

[0055] Ce: more than 0 wt% and less than 0.02 wt%

[0056] Cerium (Ce) is an element that lowers grain boundary energy due to grain boundary segregation, suppresses nucleation of {111} and {112} orientations as the recrystallization speed decreases, reduces the volume fraction of orientations that are unfavorable to magnetic properties, and increases {100} orientation and Goss orientation that are advantageous to magnetism. When the cerium is included in the non-oriented electrical steel sheet at or above the upper limit of the aforementioned range, the pinning effect due to grain boundary segregation hinders recrystallization grain growth, preventing grain growth and rather having a negative effect on the texture. Therefore, the cerium may be included in the non-oriented electrical steel sheet in an amount of more than 0 wt% and less than 0.02 wt%, and specifically, may be included in an amount of 0.0005 wt% or more and 0.018 wt% or less, or 0.001 wt% or more and 0.015 wt% or less.

[0057] The remaining Fe and other unavoidable impurities

[0058] The above-mentioned inevitable impurities are impurities mixed in during the steelmaking and manufacturing processes of non-oriented electrical steel sheets, and since this is widely known in the art, a detailed description thereof will be omitted. In addition to the components of the non-oriented electrical steel sheet described above in one embodiment of the present application, the addition of elements is not excluded, and various elements may be included within a scope that does not impair the technical spirit of the present application. When additional elements are included, they may be included to replace the remaining iron (Fe).

[0059] For example, the above-mentioned inevitable impurities may be niobium (Nb) and / or copper (Cu), and the non-oriented electrical steel sheet may include Nb: less than 0.001 wt% and / or Cu: less than 0.001 wt%.

[0060] In one example, the non-oriented electrical steel sheet may have a total of boron (B) and cerium (Ce) in wt% of more than 0% and less than or equal to 0.02%. Specifically, the total of boron (B) and cerium (Ce) may be 0.001 wt% or more and 0.02 wt% or less, 0.002 wt% or more and 0.02 wt% or less, or 0.003 wt% or more and 0.02 wt% or less. When the total of boron and cerium included in the non-oriented electrical steel sheet exceeds the upper limit of the above-mentioned range, the pinning effect due to grain boundary segregation hinders recrystallization grain growth, preventing grain growth and rather having a negative effect on the grain structure. On the other hand, the boron and the cerium can satisfy the general formula 1 described above by satisfying the above-mentioned range in the total amount included in the non-oriented electrical steel sheet, and thus can have excellent magnetic properties, specifically, low iron loss and high magnetic flux density. That is, the boron and the cerium can satisfy the general formula 1 by satisfying the above-mentioned range in the total amount included in the non-oriented electrical steel sheet, and at the same time, satisfying the above-mentioned range in the content of each.

[0061] In another example, the non-oriented electrical steel sheet may further include at least one selected from C: more than 0% and less than or equal to 0.002%, P: more than 0% and less than or equal to 0.015%, S: more than 0% and less than or equal to 0.002%, N: more than 0% and less than or equal to 0.002%, and Ti: more than 0% and less than or equal to 0.002% in weight %.

[0062] C: More than 0 wt% and less than or equal to 0.002 wt%

[0063] Carbon (C) is an element that can increase iron loss by combining with other unavoidable impurities to form carbides such as TiC and / or NbC. If the carbon is included in the non-oriented electrical steel sheet in an amount exceeding the upper limit of the aforementioned range, it can cause magnetic aging, which can adversely affect magnetic properties. Therefore, the carbon may be included in the non-oriented electrical steel sheet in an amount of more than 0 wt% and less than or equal to 0.002 wt%, and specifically, may be included in an amount of more than 0.001 wt% and less than or equal to 0.002 wt%.

[0064] P: More than 0 wt% and less than or equal to 0.015 wt%

[0065] Phosphorus (P) is an element that develops grain structure as a grain boundary segregation element. If the phosphorus is included in the non-oriented electrical steel sheet in an amount exceeding the upper limit of the aforementioned range, grain growth may be suppressed due to the segregation effect, magnetic properties may deteriorate, and cold-rollability may deteriorate. Therefore, the phosphorus may be included in the non-oriented electrical steel sheet in an amount of more than 0 wt% and less than or equal to 0.015 wt%, and specifically, may be included in an amount of more than 0.005 wt% and less than or equal to 0.010 wt%.

[0066] S: More than 0 wt% and less than or equal to 0.002 wt%

[0067] Sulfur (S) is an element that forms sulfides such as MnS and / or CuS by combining with other unavoidable impurities. If it is included in excess of the upper limit of the aforementioned range, it may increase iron loss and inhibit grain growth. Therefore, the sulfur may be included in the non-oriented electrical steel sheet in an amount of more than 0 wt% and less than or equal to 0.002 wt%, and specifically, may be included in an amount of more than 0.001 wt% and less than or equal to 0.002 wt%.

[0068] N: More than 0 wt% and less than or equal to 0.002 wt%

[0069] Nitrogen (N) is an element that forms nitrides such as AlN, TiN, and / or NbN by combining with other unavoidable impurities. If it is included in excess of the upper limit of the aforementioned range, it may increase iron loss and inhibit grain growth. Therefore, the nitrogen may be included in the non-oriented electrical steel sheet in an amount of more than 0 wt% and less than or equal to 0.002 wt%, and specifically, in an amount of more than 0.001 wt% and less than or equal to 0.0015 wt%.

[0070] Ti: More than 0 wt% and less than or equal to 0.002 wt%

[0071] Titanium (Ti) is an element that forms fine carbides and / or nitrides, such as TiC and / or TiN, by combining with other unavoidable impurities. If it is included in excess of the upper limit of the aforementioned range, it may inhibit grain growth and deteriorate magnetic properties. Therefore, the titanium may be included in the non-oriented electrical steel sheet in an amount of more than 0 wt% and less than or equal to 0.002 wt%, and specifically, in an amount of more than 0.001 wt% and less than or equal to 0.0015 wt%.

[0072] The present application also relates to a method for manufacturing a non-oriented electrical steel sheet. The method for manufacturing the non-oriented electrical steel sheet relates to the method for manufacturing the non-oriented electrical steel sheet described above. Since the specific details of the non-oriented electrical steel sheet described below are equally applicable to the non-oriented electrical steel sheet described above, they will be omitted.

[0073] The method for manufacturing a non-oriented electrical steel sheet of the present application includes a hot rolling step, a cold rolling step, and a final annealing step, and the final annealed steel sheet satisfies the general formula 1 above. According to the method for manufacturing a non-oriented electrical steel sheet of the present application, the final annealed steel sheet, i.e., the manufactured non-oriented electrical steel sheet, can satisfy the general formula 1 above, and thus, can have excellent magnetic properties, specifically, high magnetic flux density and low iron loss.

[0074] The above hot rolling step is a step for manufacturing a slab into a hot-rolled steel sheet, and is performed by reheating the slab and then hot rolling it. The composition of the slab is the same as the composition of the non-oriented electrical steel sheet, so all the contents described in the non-oriented electrical steel sheet are equally applied, and therefore, it is omitted. The reheating temperature of the slab is not particularly limited, but may be, for example, 1000°C or more and 1200°C or less, and specifically, 1110°C or more and 1150°C or less. If the reheating temperature of the slab is less than the lower limit of the above-mentioned range, the rolling load increases during hot rolling, and if it exceeds the upper limit of the above-mentioned range, precipitates such as C, S, and / or N in the slab are re-dissolved, and fine precipitates are generated in the subsequent process, which may inhibit grain growth and adversely affect magnetic properties.

[0075] In addition, the finishing rolling temperature during the hot rolling may be 860°C or more and 900°C or less, specifically 880°C or more and 900°C or less. In addition, the hot-rolled steel sheet obtained through the hot rolling may be coiled at 550°C or more and 650°C or less. The thickness of the hot-rolled steel sheet may be 1.8 mm or more and 2.6 mm or less. If the thickness of the hot-rolled steel sheet exceeds the upper limit of the above-mentioned range, the reduction ratio may increase during cold rolling, which may deteriorate the bonding structure. Therefore, the thickness of the hot-rolled steel sheet may be controlled within the above-mentioned range.

[0076] In one example, the method for manufacturing the non-oriented electrical steel sheet may further include a preliminary annealing step. The preliminary annealing step is a step for annealing the hot-rolled steel sheet that has been hot-rolled through the hot-rolling step to increase an orientation advantageous for magnetic properties, and may be performed by heating the hot-rolled steel sheet to a temperature of 900°C or higher and 1100°C or lower at a heating rate of 20°C / s or higher. Specifically, the preliminary annealing step may be performed by heating the hot-rolled steel sheet to a temperature of 900°C or higher and 1100°C or lower in a nitrogen atmosphere at a heating rate of 20°C / s or higher, maintaining the temperature range for 30 seconds or higher and 120 seconds or lower, and then cooling the hot-rolled steel sheet at a cooling rate of 30°C or higher. At this time, the preliminary annealing may be performed by uncoiling the coiled hot-rolled steel sheet. The above hot-rolled steel sheet has a {100} grain structure that is advantageous to magnetism after cold rolling and final annealing when the annealing temperature and heating rate during preliminary annealing exceed the upper limit of the above-mentioned range. <130> Defense and {113} <251> The volume fraction of the direction increases, and {334} is unfavorable for magnetism. <483> Although the volume fraction of the orientation is reduced, it is advantageous in terms of the aggregate structure, but since the average crystal grain size exceeds the above-mentioned range, the microstructure may be formed very heterogeneously after cold rolling, and orientation colonies may be formed during the final annealing, which may have a negative effect on the magnetic properties. In addition, in the case of the hot-rolled steel sheet, if the annealing temperature and heating rate during the preliminary annealing are below the lower limit of the above-mentioned range, the {100} aggregate structure, which is advantageous for magnetism after cold rolling and final annealing <130> Defense and {113} <251> The volume fraction of the direction is reduced, and {334} is unfavorable for magnetism. <483> As the volume fraction of the direction increases, the final product does not satisfy general formula 1, which may adversely affect the magnetic properties. In addition, if the holding time during preliminary annealing of the hot-rolled steel sheet is less than the lower limit of the aforementioned range, non-uniform grain growth may occur, which may adversely affect the magnetic properties of the final product.

[0077] The above hot-rolled steel sheet may have an average grain size of 100 ㎛ or more and 250 ㎛ or less during the preliminary annealing process, and all of the processed structure formed during the hot rolling, which is the previous step, may be recrystallized, that is, more than 99%. Since the above hot-rolled steel sheet has an average grain size within the aforementioned range during the preliminary annealing process, the non-oriented electrical steel sheet manufactured through the final annealing process may satisfy the general formula 1, thereby improving the magnetic properties. On the other hand, if the average grain size of the above hot-rolled steel sheet is less than the lower limit of the aforementioned range during the preliminary annealing process, the {100} grain structure, which is advantageous for magnetism after cold rolling and final annealing, may be <130> Defense and {113} <251> The volume fraction of the direction is reduced, and {334} is unfavorable for magnetism. <483> The volume fraction of the direction increases, so that the final product does not satisfy general formula 1, which may have a negative effect on the magnetic properties. In addition, if the average grain size of the hot-rolled steel sheet exceeds the upper limit of the above-mentioned range during the preliminary annealing process, the {100} grain structure, which is advantageous for magnetism, is formed after cold rolling and final annealing. <130> Defense and {113} <251> The volume fraction of the direction increases, and {334} is unfavorable for magnetism. <483> Although the volume fraction of the orientation is reduced, which is advantageous in terms of the aggregate structure, the average crystal grain size exceeds the aforementioned range, so that the microstructure may be formed very heterogeneously after cold rolling, and during the final annealing, orientation colonies may be formed, which may have a negative effect on the magnetic properties.

[0078] Afterwards, the annealed hot-rolled steel sheet can be further pickled using a pickling solution to remove the oxide layer formed on the surface.

[0079] The step of manufacturing the above cold-rolled steel sheet is a step for manufacturing the hot-rolled steel sheet into a cold-rolled steel sheet, and is performed through cold rolling. The reduction ratio during the cold rolling may be 80% or more and 90% or less. The thickness of the cold-rolled steel sheet may be 0.1 mm or more and 0.5 mm or less, and specifically, 0.2 mm or more and 0.5 mm or less.

[0080] The final annealing step is a step for securing magnetic properties by growing the crystal grains to a specific size, and is performed by heat treating the cold-rolled steel sheet. For example, the final annealing may be performed by heating the steel to 900°C to 1100°C at a heating rate of 10°C / s or more, heat-treating at this temperature range for 5 to 70 seconds, and then cooling at a cooling rate of 20°C / s or more. The final annealing step is performed at the heating rate, temperature, time, and cooling rate within the aforementioned ranges, thereby reducing iron loss and deriving an optimal grain size considering mechanical properties. In contrast, if the heating rate, temperature, and time of the final annealing step exceed the upper limit of the aforementioned range, the grain size may become coarser, which may increase eddy current loss. In addition, if the heating rate, temperature, and time of the final annealing step are less than the lower limit of the aforementioned range, the grain size may become fine, which may increase hysteresis loss.

[0081] At this time, the final annealing step can be performed in an atmosphere of 10% to 100% hydrogen and 0% to 90% nitrogen, specifically, 20% to 40% hydrogen and 60% to 80% nitrogen. The method for manufacturing the non-oriented electrical steel sheet can further smoothen the surface condition of the steel sheet by performing the final annealing step in an atmosphere within the aforementioned range.

[0082] The above non-oriented electrical steel sheet may have an average grain size of 80 ㎛ or more and 160 ㎛ or less during the final annealing process, and all of the processed structure formed during the previous cold rolling process, that is, more than 99%, may be recrystallized. If the average grain size of the above non-oriented electrical steel sheet is less than the lower limit of the above-mentioned range during the final annealing process, hysteresis loss may increase due to the fine grain size, and if it exceeds the upper limit of the above-mentioned range, eddy current loss may increase, which may increase iron loss.

[0083] In another example, the method for manufacturing the non-oriented electrical steel sheet may further include a step of forming a coating layer to improve the punchability and secure insulation. Specifically, the step of forming the coating layer is a step of forming a coating layer to provide insulation to the surface of the final annealed steel sheet, and is performed after the final annealing step. For example, a chromate-based coating solution, or a chromium-free coating solution, which is an organic-inorganic composite coating solution that does not contain chromium, may be applied to the surface of the final annealed steel sheet, and then baked to form a coating layer. At this time, the coating layer may be formed to a thickness of 0.1 ㎛ to 5 ㎛. The method for manufacturing the non-oriented electrical steel sheet may further include the step of forming the coating layer, thereby maintaining insulation between upper and lower non-oriented electrical steel sheets when stacking a plurality of non-oriented electrical steel sheets, thereby reducing eddy current loss.

[0084]

[0085] Hereinafter, the present application will be described in more detail through examples according to the present application and comparative examples not according to the present application, but the scope of the present application is not limited by the examples presented below.

[0086]

[0087] Example 1

[0088] Manufacturing of non-oriented electrical steel sheets

[0089] A slab was manufactured by steelmaking and continuous casting using the components shown in Table 1 below, the remaining Fe, and other unavoidable impurities, and after reheating at a temperature of 1130°C, hot rolling was performed at a finishing temperature of 880°C to manufacture a hot-rolled steel sheet having a thickness of 2.0 mm.

[0090] Afterwards, the hot-rolled steel sheet was coiled at a coiling temperature of 600°C.

[0091] Afterwards, the hot-rolled steel sheet was pre-annealed by heating it to 1000°C at a heating rate of 20°C / s in an atmosphere of 100% nitrogen, maintaining it at this temperature for 100 seconds, and then cooling it at a cooling rate of 30°C / s.

[0092] Afterwards, the pre-annealed hot-rolled steel plate was cold-rolled at a reduction ratio of 87.5% to manufacture a cold-rolled steel plate with a thickness of 0.25 mm.

[0093] Thereafter, the cold-rolled steel sheet was heated to 1000°C at a heating rate of 20°C / s in an atmosphere of 30% hydrogen and 70% nitrogen, maintained at this temperature for 60 seconds, and then cooled at a cooling rate of 30°C / s to perform final annealing, thereby manufacturing a non-oriented electrical steel sheet.

[0094] Slab composition (wt%)SiMnAlCPSNTiBCe3.30.20530.90250.00200.010.00180.00120.00130.0120.0075

[0095] Examples 2 to 8 and Comparative Examples 1 to 7

[0096] Manufacturing of non-oriented electrical steel sheets

[0097] A non-oriented electrical steel sheet was manufactured in the same manner as Example 1, except that the contents of boron (B) and cerium (Ce) in the composition of the slab were changed as shown in Table 2 below.

[0098] Slab Composition (% by weight) BCeExample 20.0110.0053Example 30.00230.0137Example 40.0010.0145Example 50.010.002Example 60.00870.0018Example 70.00230.0049Example 80.0020.0012Comparative Example 10.020.04Comparative Example 20.0180.039Comparative Example 30.0350.008Comparative Example 40.0080.027Comparative Example 50.0110.01Comparative Example 60.0195-Comparative Example 7-0.0195

[0099] Examples 9 to 12 and Comparative Examples 8 to 12

[0100] Manufacturing of non-oriented electrical steel sheets

[0101] A non-oriented electrical steel sheet was manufactured in the same manner as in Example 1, except that the pre-annealing conditions of the hot-rolled steel sheet were changed as shown in Table 3 below. In this case, pre-annealing was not performed in Comparative Example 8.

[0102] Atmosphere (%)Heating rate (℃ / s)Maintenance temperature (℃)Maintenance time (sec)Cooling rate (℃ / s)Example 9Nitrogen 1003510507575Example 10Nitrogen 1005510009545Example 11Nitrogen 1006510308565Example 12Nitrogen 1008598010530Comparative Example 8-----Comparative Example 9Nitrogen 100258501308Comparative Example 10Nitrogen 1002082315010Comparative Example 11Nitrogen 1001075018020Comparative Example 12Nitrogen 100870021025

[0103] Evaluation Example 1. Collective Organization Evaluation

[0104] For each of the non-oriented electrical steel sheets manufactured in the examples and comparative examples, the orientation of the grain structure was measured in an area of ​​1000 ㎛ Х 1000 ㎛ or more using electron backscatter diffraction (EBSD), and then the orientation of the measured grain structure was calculated using the orientation distribution function (ODF) to obtain a, b, and c shown in the general formula 1 below, and based on the results, the calculations were performed using the general formula 1 below and are shown in Table 4 below.

[0105] [General Formula 1]

[0106]

[0107] In the general formula 1 above, a is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45° max ), and b is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, and φ2=45° max ), and c is the maximum intensity (f(g)) of the orientation distribution function in the set structure appearing at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45° max )am.

[0108]

[0109] Evaluation Example 2. Iron loss and magnetic flux density evaluation

[0110] In each of the examples and comparative examples, a chromium-free coating solution was applied to the surface of the non-oriented electrical steel sheet manufactured, and then heated to 300°C, slowly cooled, and dried to form a coating layer. Then, the non-oriented electrical steel sheet with the coating layer formed on the surface was punched into a width of 60 mm × length of 60 mm, and then the magnetism was measured at angles of 0° and 90° with respect to the rolling direction during cold rolling using a single sheet tester, and the average values ​​are shown in Table 4 below. At this time, W 10 / 400 It means the iron loss when a magnetic flux density of 1.0 T is induced at a high frequency of 400 Hz. In addition, B 50 refers to the magnetic flux density induced in a magnetic field of 5000 A / m.

[0111]

[0112] Evaluation Example 3. Grain Size Evaluation

[0113] In the manufacturing of the non-oriented electrical steel sheets manufactured in each of the examples and comparative examples, the average grain size formed in the hot-rolled steel sheet during the preliminary annealing process was measured according to ASTM E112, and the results are shown in Table 4 below.

[0114] abcGeneral formula 1 Calculated value Average grain size (㎛) during pre-annealing W 10 / 400 (W / kg)B 50 (T) Example 15.34.78.25.420112.511.65 Example 24.63.857.323812.461.66 Example 35.13.74.87.821012.431.66 Example 44.43.23.78.811612.171.67 Example 564.44.79.415012.021.67 Example 64.54.349.813411.851.67 Example 75.84.94.111.418911.441.65 Example 86.36.34.612.317610.891.68 Example 95.14.88.55.211512.831.64Example 105.44.18.05.515812.771.64Example 115.34.78.25.420112.511.64Example 125.54.28.15.124112.831.64Comparative Example 12.11.114.10.918315.561.60Comparative Example 23.2313.52.012515.121.64Comparative Example 33.53.211.22.719514.571.63Comparative Example 44.13.89.53.723214.121.59Comparative Example 54.34.28.74.411213.891.61Comparative example 64.43.29.33.513514.321.62Comparative example 74.13.78.83.918514.881.61Comparative example 80.8120.50.4Not measurable15.781.61Comparative example 91.31.818.80.83314.231.62Comparative example 101.52.615.81.38513.441.63Comparative example 114.36.17.26.927513.851.63Comparative example 124.15.87.56.333714.311.63

[0115] As shown in Tables 3 and 4 above, the non-oriented electrical steel sheets manufactured in each of Examples 1 to 12 satisfy the general formula 1, and the average grain size formed in the hot-rolled steel sheet during the preliminary annealing process during the manufacture of the non-oriented electrical steel sheet satisfies a specific range, thereby confirming that they have low iron loss and high magnetic flux density. In contrast, the non-oriented electrical steel sheets manufactured in each of Comparative Examples 1 to 5 do not satisfy the general formula 1, and thus it was confirmed that even if the average grain size formed in the hot-rolled steel sheet during the preliminary annealing process during the manufacture of the non-oriented electrical steel sheet satisfies a specific range, it is difficult to secure both low iron loss and high magnetic flux density at the same time. In addition, the non-oriented electrical steel sheets manufactured in each of Comparative Examples 6 to 12 do not satisfy the general formula 1, and since the average grain size formed in the hot-rolled steel sheet during the preliminary annealing process during the manufacture of the non-oriented electrical steel sheet does not satisfy a specific range, it was confirmed that they have high iron loss and low magnetic flux density.

Claims

1. Contains, in weight%, Si: 1.8% or more and 3.8% or less, Mn: 0.2% or more and 0.4% or less, Al: 0.8% or more and 1.5% or less, B: more than 0% and less than 0.02%, and Ce: more than 0% and less than 0.02%, and the remainder includes Fe and inevitable impurities. Non-oriented electrical steel sheet satisfying the following general formula 1: [General formula 1] In the above general formula 1, a is the maximum intensity (f(g)) of the orientation distribution function in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45°. max ) and, b is the maximum intensity (f(g)) of the orientation distribution function in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, and φ2=45°. max ) and c is the maximum intensity (f(g)) of the orientation distribution function in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45°. max )am.

2. In paragraph 1, In the set of structures that appear at Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g)) max ) is a non-oriented electrical steel sheet with a grade of 4.4 or more and 7.0 or less.

3. In paragraph 1, In the set of structures that appear at Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g)) max ) has a orientation (g) of {113} <251> Non-oriented electrical steel sheet for defense.

4. In paragraph 1, In the set of structures that appear at Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g)) max ) is a non-oriented electrical steel sheet with a grade of 3.0 or more and 7.0 or less.

5. In paragraph 1, In the set of structures that appear at Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g)) max ) has a direction (g) of {100} <130> Non-oriented electrical steel sheet for defense.

6. In paragraph 1, In the set of structures that appear at Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g)) max ) is a non-oriented electrical steel sheet with a grade of 3.0 or more and 8.5 or less.

7. In paragraph 1, In the set of structures that appear at Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45°, the maximum intensity of the orientation distribution function (f(g)) max ) has a orientation (g) of {334} <483> Non-oriented electrical steel sheet for defense.

8. In paragraph 1, A non-oriented electrical steel sheet in which the sum of the above B and the above Ce is more than 0% and less than or equal to 0.02% in weight%.

9. In paragraph 1, Non-oriented electrical steel sheet further comprising at least one selected from among C: more than 0% and 0.002% or less, P: more than 0% and 0.015% or less, S: more than 0% and 0.002% or less, N: more than 0% and 0.002% or less, and Ti: more than 0% and 0.002% or less, in weight%.

10. In paragraph 1, Iron loss W measured at angles of 0° and 90° with respect to the rolling direction during cold rolling 10 / 400 The average of is less than 13.00 W / kg and the magnetic flux density (B 50 ) Non-oriented electrical steel sheet having an average of 1.64 T or higher.

11. A step of hot rolling after reheating a slab containing Si: 1.8% or more and 3.8% or less, Mn: 0.2% or more and 0.4% or less, Al: 0.8% or more and 1.5% or less, B: more than 0% and less than 0.02%, and Ce: more than 0% and less than 0.02% by weight, and the remainder including Fe and unavoidable impurities; A step for manufacturing a cold rolled steel sheet by cold rolling; and It includes a step of final annealing of the above cold rolled steel sheet, A method for manufacturing a non-oriented electrical steel sheet, wherein the final annealed steel sheet satisfies the following general formula 1: [General formula 1] In the above general formula 1, a is the maximum intensity (f(g)) of the orientation distribution function in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45°. max ) and, b is the maximum intensity (f(g)) of the orientation distribution function in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, and φ2=45°. max ) and c is the maximum intensity (f(g)) of the orientation distribution function in the set structure that appears at the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=35° to 60°, and φ2=45°. max )am.

12. In paragraph 11, In the final annealed steel plate, the maximum intensity (f(g)) of the orientation distribution function in the Euler angles (φ1, Φ, φ2) of φ1=15° to 35°, Φ=0° to 35°, and φ2=45° max ) is a method for manufacturing a non-oriented electrical steel sheet having a hardness of 4.4 or higher and 7.0 or lower.

13. In paragraph 11, In the final annealed steel plate, the maximum intensity (f(g)) of the orientation distribution function in the Euler angles (φ1, Φ, φ2) of φ1=55° to 75°, Φ=0° to 20°, and φ2=45° max ) is a method for manufacturing a non-oriented electrical steel sheet having a hardness of 3.0 or more and 7.0 or less.

14. In paragraph 11, In the final annealed steel plate, the maximum intensity (f(g)) of the orientation distribution function in the Euler angles (φ1, Φ, φ2) that appear at φ1=15° or more and 35° or less, Φ=35° or more and 60° or less, and φ2=45° max ) is a method for manufacturing a non-oriented electrical steel sheet having a hardness of 3.0 or more and 8.5 or less.

15. In paragraph 11, The above slab is a method for manufacturing a non-oriented electrical steel sheet in which the sum of the above B and the above Ce is more than 0% and less than or equal to 0.02% in weight%.

16. In paragraph 11, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further includes at least one selected from the group consisting of C: more than 0% and 0.002% or less, P: more than 0% and 0.015% or less, S: more than 0% and 0.002% or less, N: more than 0% and 0.002% or less, and Ti: more than 0% and 0.002% or less, in wt%.

17. In paragraph 11, It further includes a step of pre-annealing the hot rolled steel sheet after going through the above hot rolling step, A method for manufacturing a non-oriented electrical steel sheet, wherein the above preliminary annealing step is performed by heating the hot-rolled steel sheet to 900°C or higher and 1100°C or lower at a heating rate of 20°C / s or higher.

18. In paragraph 17, The above hot-rolled steel sheet is a method for manufacturing a non-oriented electrical steel sheet having an average grain size of 100 ㎛ or more and 250 ㎛ or less during the preliminary annealing process.

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