Non-oriented electrical steel sheet and method for manufacturing same

Abstract

A non-oriented electrical steel sheet according to an embodiment of the present invention comprises, in weight %: 1.5-5.0% of Si; 0.1-2.0% of Al; and 0.1-2.0% of Mn, the remainder being Fe and inevitable impurities, and has a {001}<100> orientation strength, expressed as an orientation distribution function (ODF), of 3.0 or more, and a {011}<100> orientation strength that is greater than the {001}<100> orientation strength.

Description

Non-oriented electrical steel sheet and manufacturing method thereof

[0001] One embodiment of the present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same. Specifically, one embodiment of the present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same, wherein, in a process of performing preliminary cold rolling and cold rolling, the reduction ratio in each pass of the cold rolling is controlled to develop a specific aggregate structure and maximize magnetic anisotropy.

[0002] Non-oriented electrical steel is primarily used in motors that convert electrical energy into mechanical energy. This process requires excellent magnetic properties to achieve high efficiency. In particular, with the recent rise in eco-friendly vehicles powered by motors instead of internal combustion engines, demand for non-oriented electrical steel, used as a drive motor core material, is increasing. This demand is driven by the need for non-oriented electrical steel with both superior magnetic properties and strength.

[0003] The magnetic properties of non-oriented electrical steel are primarily assessed by core loss and magnetic flux density. Core loss refers to the energy loss occurring at a specific magnetic flux density and frequency, while magnetic flux density represents the degree of magnetization achieved under a specific magnetic field. Lower core loss allows for more energy-efficient motors under similar conditions, while higher flux density allows for smaller motors and reduced copper loss. Therefore, non-oriented electrical steel with low core loss and high flux density can be used to create drive motors with superior efficiency and torque, thereby improving the driving range and power output of eco-friendly vehicles.

[0004] The characteristics of non-oriented electrical steel sheets that must be considered also vary depending on the operating conditions of the motor. The general standard for evaluating the characteristics of non-oriented electrical steel sheets used in motors is widely used as W15 / 50, which is the iron loss when a 1.5T magnetic field is applied at a commercial frequency of 50Hz. However, in the case of non-oriented electrical steel sheets with a thickness of 0.35mm or less used in eco-friendly vehicle drive motors, magnetic characteristics are often important at low fields of 1.0T or less and high frequencies of 400Hz or higher, so W 10 / 400 The properties of non-oriented electrical steel sheets are often evaluated by iron loss.

[0005] With the recent adoption of non-oriented electrical steel sheets for electric vehicle drive motors, efforts are being made to maximize magnetic anisotropy, rather than the generally desired uniform magnetic properties, to increase motor output. Maximizing magnetic anisotropy increases motor output, leading to improved overall efficiency. Magnetic anisotropy, in this case, refers to a significant difference in magnetic flux density measured in the rolling direction and in a direction at a 55° angle to the rolling direction.

[0006] One embodiment of the present invention provides a non-oriented electrical steel sheet and a method for manufacturing the same. Specifically, one embodiment of the present invention provides a non-oriented electrical steel sheet and a method for manufacturing the same, wherein, in a process of performing preliminary cold rolling and cold rolling, the reduction ratio in each pass of the cold rolling is controlled to develop a specific aggregate structure, thereby maximizing magnetic anisotropy.

[0007] A non-oriented electrical steel sheet according to one embodiment of the present invention contains Si: 1.5 to 5.0% by weight, Al: 0.1 to 2.0%, Mn: 0.1 to 2.0%, the remainder being Fe and inevitable impurities, and is represented by an orientation distribution function (ODF) of {001} <100> Defense strength is 3.0 or higher, {011} <100> Defense strength is {001} <100> Higher than the defense strength.

[0008] A non-oriented electrical steel sheet according to one embodiment of the present invention includes a surface portion and a center portion from the surface of the steel sheet to a depth of 50 ㎛ in an inward direction, and a ratio of the average grain size in the surface portion to the average grain size in the center portion may be 0.6 to 0.8.

[0009] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include at least one of P: 0.1 wt% or less (excluding 0%), C: 0.005 wt% or less (excluding 0%), S: 0.005 wt% or less (excluding 0%), Ti: 0.005 wt% or less (excluding 0%), and N: 0.005 wt% or less (excluding 0%).

[0010] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include 0.005 to 0.200 wt% of each or a combined amount of one or more of Sn, Sb, Bi, Pb, Ge, and As.

[0011] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include at least one of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less (excluding 0%), Zn: 0.01 wt% or less (excluding 0%), and Co: 0.05 wt% or less (excluding 0%).

[0012] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include at least one of Mo: 0.03 wt% or less (excluding 0%), B: 0.0050 wt% or less (excluding 0%), V: 0.0050 wt% or less (excluding 0%), Ca: 0.0050 wt% or less (excluding 0%), Nb: 0.0050 wt% or less (excluding 0%), Zr: 0.005 wt% or less (excluding 0%), Te: 0.01 wt% or less (excluding 0%), and Mg: 0.0050 wt% or less (excluding 0%).

[0013] A non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following equation 1.

[0014] [Formula 1]

[0015] B 50L - B 50(55°) ≥ 0.11 T

[0016] (B in Equation 1 50L Magnetic flux density B measured in the rolling direction 50 , B 50(55°) is the magnetic flux density B measured in a direction at an angle of 55° to the rolling direction. 50 )

[0017]

[0018] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention comprises the steps of: hot-rolling a slab containing, by weight %, Si: 1.5 to 5.0%, Al: 0.1 to 2.0%, and Mn: 0.1 to 2.0%, with the remainder including Fe and unavoidable impurities, to manufacture a hot-rolled steel sheet; a step of preliminarily cold-rolling the hot-rolled steel sheet; a first annealing step of annealing the preliminarily cold-rolled steel sheet; a step of cold-rolling the annealed steel sheet to manufacture a cold-rolled sheet; and a second annealing step of annealing the cold-rolled sheet.

[0019] In the step of manufacturing a cold-rolled sheet, cold rolling is performed through three or more passes, and the reduction ratios in the first, second, and third passes may each be 23 to 33%.

[0020] The slab may further include at least one of P: 0.1 wt% or less (excluding 0%), C: 0.005 wt% or less (excluding 0%), S: 0.005 wt% or less (excluding 0%), Ti: 0.005 wt% or less (excluding 0%), and N: 0.005 wt% or less (excluding 0%).

[0021] The slab may further contain 0.005 to 0.200 wt% of each or a combination of one or more of Sn, Sb, Bi, Pb, Ge and As.

[0022] The slab may further include at least one of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less (excluding 0%), and Zn: 0.01 wt% or less (excluding 0%).

[0023] The slab may further include at least one of Mo: 0.03 wt% or less (excluding 0%), B: 0.0050 wt% or less (excluding 0%), V: 0.0050 wt% or less (excluding 0%), Ca: 0.0050 wt% or less (excluding 0%), Nb: 0.0050 wt% or less (excluding 0%), Zr: 0.005 wt% or less (excluding 0%), Te: 0.01 wt% or less (excluding 0%), Co: 0.05 wt% or less (excluding 0%), and Mg: 0.0050 wt% or less (excluding 0%).

[0024] After manufacturing a hot-rolled steel sheet, subsequent steps can be performed while the scale remaining on the hot-rolled steel sheet remains.

[0025] In the first annealing stage, 0.1 to 1.0 kgf / mm 2 It can be annealed while applying tension.

[0026] The first annealing step can be performed at a temperature of 800 to 1100°C for 5 to 20 seconds.

[0027] During the manufacturing process of a cold rolled sheet, the product of the diameter (mm) of the work roll and the coefficient of friction (μ) between the work roll and the material may be 1.5 to 9.0.

[0028] A non-oriented electrical steel sheet according to one embodiment of the present invention has an improved texture and thus has high magnetic anisotropy, and thus can obtain high torque when manufactured into an automobile motor.

[0029] Figure 1 is a schematic diagram showing a cross-section of a non-oriented electrical steel sheet according to one embodiment of the present invention.

[0030] Figure 2 is a graph showing the orientation distribution function (ODF) results of the non-oriented electrical steel sheet manufactured in Example B6.

[0031] The terms first, second, and third, etc., are used to describe, but are not limited to, various parts, components, regions, layers, and / or sections. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used herein, the singular forms "singular" and "comprising" include plural forms as well, unless the context clearly dictates otherwise. The word "comprising" as used herein specifies a particular feature, region, integer, step, operation, element, and / or component, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0033] When a part is referred to as being "on" or "over" another part, it can be directly on or over the other part, or there may be other parts intervening. Conversely, when a part is referred to as being "directly on" another part, there are no other parts intervening.

[0034] Also, unless otherwise stated, % means weight%, and 1 ppm is 0.0001 weight%.

[0035] In one embodiment of the present invention, the inclusion of additional elements means including the remaining iron (Fe) in an amount equivalent to the additional amount of the additional elements.

[0036] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

[0037] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0038]

[0039] A non-oriented electrical steel sheet according to one embodiment of the present invention contains, in wt%, Si: 1.5 to 5.0%, Al: 0.1 to 2.0%, Mn: 0.1 to 2.0%, and the remainder includes Fe and inevitable impurities.

[0040] Below, the reasons for the limitation of the components of non-oriented electrical steel sheets are explained.

[0041]

[0042] Si: 1.5 to 5.0 wt%

[0043] Silicon (Si) increases the resistivity of the material, thereby reducing iron loss, and enhances strength through solid solution strengthening. If too little Si is added, the iron loss and strength improvement effects may be insufficient. If too much Si is added, the material becomes brittle, leading to a sharp decline in rolling productivity and the formation of a surface oxide layer and oxides that are detrimental to magnetism. Therefore, Si may be included in an amount of 1.5 to 5.0 wt%. More specifically, it may be included in an amount of 2.0 to 4.5 wt%. Even more specifically, it may be included in an amount of 2.5 to 4.0 wt%.

[0044]

[0045] Al: 0.1 to 2.0 wt%

[0046] Aluminum (Al) increases the resistivity of the material, thereby reducing iron loss and improving rollability, and plays a role in improving workability during cold rolling. If too little Al is added, it may be difficult to achieve the effect of reducing high-frequency iron loss, and the precipitation temperature of AlN may be lowered, which may cause fine nitride formation, which may reduce magnetism. If too much Al is added, excessive nitride formation may deteriorate magnetism, and problems may occur in all processes such as steelmaking and continuous casting, which may significantly reduce productivity. Therefore, Al may be included in an amount of 0.1 to 2.0 wt%. More specifically, it may be included in an amount of 0.15 to 1.7 wt%. Even more specifically, it may be included in an amount of 0.2 to 1.6 wt%.

[0047]

[0048] Mn: 0.1 to 2.0 wt%

[0049] Manganese (Mn) improves iron loss by increasing the resistivity of the material and plays a role in forming sulfides. If too little Mn is added, fine sulfides are formed, causing magnetic deterioration, and if too much Mn is added, fine MnS is excessively precipitated and promotes the formation of {111} texture, which is unfavorable for magnetism, resulting in a rapid decrease in magnetic flux density. Therefore, Mn may be included in an amount of 0.1 to 2.0 wt%. More specifically, it may be included in an amount of 0.15 to 1.7 wt%. More specifically, it may be included in an amount of 0.2 to 1.6 wt%.

[0050]

[0051] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include at least one of P: 0.1 wt% or less (excluding 0%), C: 0.005 wt% or less (excluding 0%), S: 0.005 wt% or less (excluding 0%), Ti: 0.005 wt% or less (excluding 0%), and N: 0.005 wt% or less (excluding 0%).

[0052] P: 0.1 wt% or less

[0053] Phosphorus (P) not only plays a role in increasing the resistivity of a material, but also can improve magnetic flux density as a grain boundary segregation element. However, if too much P is added, it increases the brittleness of the steel plate, resulting in poor weldability. More specifically, P may be included in an amount of 0.0001 to 0.0500 wt%. More specifically, P may be included in an amount of 0.0010 to 0.0200 wt%.

[0054] C: 0.005 wt% or less

[0055] Carbon (C) can cause magnetic aging and combine with other impurity elements to form carbides, thereby hindering grain boundary or domain wall movement and deteriorating magnetic properties. More specifically, C can be included in an amount of 0.0001 to 0.0035 wt%.

[0056] S: 0.005 wt% or less

[0057] Sulfur (S) can form fine precipitates, MnS and CuS, thereby deteriorating magnetic properties and hot workability. More specifically, S may be included in an amount of 0.0001 to 0.0050 wt%. More specifically, S may be included in an amount of 0.0005 to 0.0045 wt%.

[0058] Ti: 0.005 wt% or less

[0059] Titanium (Ti) has a strong tendency to form precipitates within the steel, and can deteriorate iron loss by forming fine carbides, nitrides, or sulfides within the base metal, thereby inhibiting grain growth and domain wall migration. More specifically, Ti may be included in an amount of 0.0001 to 0.0050 wt%. More specifically, Ti may be included in an amount of 0.0005 to 0.0030 wt%.

[0060]

[0061] N: 0.005 wt% or less

[0062] Nitrogen (N) not only forms fine AlN precipitates within the base material, but also combines with other impurities to form fine precipitates, thereby inhibiting grain growth and domain wall migration, thereby worsening iron loss. More specifically, N may be included in an amount of 0.0001 to 0.0050 wt%. More specifically, N may be included in an amount of 0.0005 to 0.0030 wt%.

[0063]

[0064] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include 0.005 to 0.200 wt% of each or a combined amount of one or more of Sn, Sb, Bi, Pb, Ge, and As.

[0065] Sn

[0066] Tin (Sn) can be added to improve magnetism because it improves the material's texture by segregating at grain boundaries and surfaces and plays a role in suppressing surface oxidation. If too much Sn is added, grain boundary segregation becomes severe, which deteriorates the surface quality and increases hardness, which can cause cold-rolled sheet fracture and reduce rollability. Specifically, Sn can be further included in an amount of 0.005 to 0.200 wt%. More specifically, it can be further included in an amount of 0.010 to 0.080 wt%.

[0067] Sb

[0068] Antimony (Sb) can be additionally added to improve magnetism because it improves the material's texture and suppresses surface oxidation by segregating at grain boundaries and surfaces. If too much Sb is added, grain boundary segregation becomes severe, deteriorating surface quality and increasing hardness, which can cause cold-rolled sheet fracture and reducing rollability. Specifically, Sb can be further included in an amount of 0.005 to 0.200 wt%. More specifically, it can be further included in an amount of 0.010 to 0.080 wt%.

[0069] Bi, Pb, Ge, and As

[0070] When added, bismuth (Bi), lead (Pb), germanium (Ge) and arsenic (As) segregate at grain boundaries, thereby relieving stress concentration at grain boundaries during cold rolling, and thus reducing stress concentration in the subsequent recrystallization annealing process. <111> / ND By suppressing the recrystallization of the grains, the magnetic flux density is improved. If these are added appropriately, the aforementioned effects can be additionally obtained. However, if they are included in excessive amounts, segregation may occur in large quantities, inhibiting grain growth and lowering the magnetic flux density and iron loss.

[0071]

[0072] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include at least one of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less (excluding 0%), Zn: 0.01 wt% or less (excluding 0%), and Co: 0.05 wt% or less (excluding 0%).

[0073] Cu: 0.005 to 0.200 wt%

[0074] Copper (Cu) forms sulfides with manganese (Mn). If too little Cu is added, fine precipitation of (Cu · Mn)S may occur, degrading magnetism. If too much Cu is added, high-temperature embrittlement may occur, leading to cracks during rolling or hot rolling. More specifically, Cu may be included in an amount of 0.01 to 0.10 wt%.

[0075] Cr: 0.01 to 0.50 wt%

[0076] Chromium (Cr) increases resistivity and improves iron loss. If too little Cr is added, the resistivity-enhancing effect may not be sufficient. If too much Cr is added, the magnetic flux density may decrease. More specifically, Cr may be included in an amount of 0.050 to 0.20 wt%.

[0077] Ni: 0.05 wt% or less

[0078] Nickel (Ni) can react with impurity elements to form fine sulfides, carbides, and nitrides, which can have a detrimental effect on magnetism. More specifically, it can contain 0.001 to 0.03 wt% of Ni.

[0079] Zn: 0.01 wt% or less

[0080] Zinc (Zn) can act as an impurity and degrade magnetism if the content is excessive. Therefore, Zn may be added further within the aforementioned range. More specifically, Zn may be included in an amount of 0.001 to 0.005 wt%.

[0081] Co: 0.05 wt% or less

[0082] Cobalt (Co) does not form fine precipitates that reduce the magnetism of steel sheets, but it can increase high-temperature strength and cause poor coil shape after hot rolling.

[0083]

[0084] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include at least one of Mo: 0.03 wt% or less (excluding 0%), B: 0.0050 wt% or less (excluding 0%), V: 0.0050 wt% or less (excluding 0%), Ca: 0.0050 wt% or less (excluding 0%), Nb: 0.0050 wt% or less (excluding 0%), Zr: 0.0050 wt% or less (excluding 0%), Te: 0.0100 wt% or less (excluding 0%), and Mg: 0.0050 wt% or less (excluding 0%).

[0085] Mo: 0.030 wt% or less

[0086] When molybdenum (Mo) is added in excessive amounts, it may suppress segregation of segregating elements, thereby reducing the effect of improving the texture. Therefore, Mo may be included in an amount of 0.03 wt% or less. The lower limit is not particularly limited, but since it plays a role in improving the texture by segregating on the surface and grain boundaries, it may be included in an amount of 0.001 wt% or more. More specifically, Mo may be included in an amount of 0.001 to 0.010 wt%. More specifically, Mo may be included in an amount of 0.005 to 0.010 wt%.

[0087] B: 0.0050 wt% or less

[0088] Excessive addition of boron (B) can cause deterioration of magnetism through the formation of inclusions in the steel. Therefore, B may be included in an amount of 0.005 wt% or less. The lower limit is not particularly limited, but may be 0.0001 wt% due to steelmaking costs. More specifically, B may be included in an amount of 0.0001 to 0.0030 wt%.

[0089] V: 0.0050 wt% or less

[0090] Vanadium (V) has a very strong tendency to form precipitates within the steel, and forms fine carbides or nitrides within the base metal, thereby inhibiting grain growth and domain wall migration, thereby deteriorating iron loss. Therefore, the V content may be 0.0050 wt% or less. The lower limit is not particularly limited, but may be 0.0003 wt% due to steelmaking costs. That is, V may be included in an amount of 0.0003 to 0.0050 wt%. More specifically, V may be included in an amount of 0.0003 to 0.0030 wt%.

[0091] Ca: 0.0050 wt% or less

[0092] Calcium (Ca) has a strong tendency to form precipitates within the steel, and forms fine sulfides within the parent material, which inhibits grain growth and domain wall movement, thereby deteriorating iron loss.

[0093] Nb: 0.0050 wt% or less

[0094] Niobium (Nb) has a very strong tendency to form precipitates in steel, and forms fine carbides or nitrides inside the base metal, which inhibits grain growth and domain wall migration, thereby deteriorating iron loss. Therefore, the Nb content may be 0.0050 wt% or less. The lower limit is not particularly limited, but may be 0.0003 wt% due to steelmaking costs. That is, Nb may be included in an amount of 0.0003 to 0.0050 wt%. More specifically, Nb may be included in an amount of 0.0003 to 0.0030 wt%.

[0095] Zr: 0.0050 wt% or less

[0096] Excessive addition of zirconium (Zr) can cause deterioration of magnetism through the formation of inclusions in the steel. Therefore, Zr can be included in an amount of 0.005 wt% or less. The lower limit is not particularly limited, but may be 0.0001 wt% due to steelmaking costs. That is, Zr can be included in an amount of 0.0001 to 0.0050 wt%. More specifically, it can be included in an amount of 0.0005 to 0.0030 wt%.

[0097] Te: 0.0100 wt% or less

[0098] Tellurium (Te) diffuses into the oxide layer on the surface of a hot-rolled coil, increases the coefficient of friction between the oxide layer and the rolling work rolls, and concentrates under the oxide layer to improve hardness. Therefore, it can be added to prevent the fractured oxide layer during rolling from being pressed into the base metal and to be removed. If the amount of Te added is too small, the effect may be minimal. If too much Te is added, the oxide layer is easily removed, and the base metal comes into direct contact with the work rolls, reducing the effect. In addition, deformation bands may be excessively generated in the steel sheet during cold rolling, which may lead to the development of a {111} / ND texture that is unfavorable for magnetism. More specifically, tellurium may be included in an amount of 0.0001 to 0.007 wt%.

[0099] Mg: 0.0050 wt% or less

[0100] Magnesium (Mg) is an element that mainly combines with sulfur to form sulfides, and can affect the surface oxide layer of the steel base. Therefore, Mg may be included in an amount of 0.0050 wt% or less. The lower limit is not particularly limited, but may be set to 0.0001 wt% due to steelmaking costs. That is, Mg may be included in an amount of 0.0001 to 0.0050 wt%. More specifically, it may be included in an amount of 0.0005 to 0.0030 wt%.

[0101]

[0102] The remainder comprises iron (Fe) and unavoidable impurities. Unavoidable impurities are impurities mixed in during the steelmaking process and the manufacturing process of non-oriented electrical steel sheets. Since these impurities are widely known in the art, a detailed description thereof will be omitted. In one embodiment of the present invention, the addition of elements other than the aforementioned alloy components is not excluded, and various elements may be included within a scope that does not impair the technical spirit of the present invention. When additional elements are included, they are included in place of the remainder, iron (Fe).

[0103]

[0104] As described above, in one embodiment of the present invention, by appropriately controlling the alloy composition of the steel sheet and performing preliminary cold rolling and cold rolling, and controlling the reduction ratio in each pass during cold rolling, a specific aggregate structure can be developed, thereby maximizing magnetic anisotropy.

[0105] Specifically, the non-oriented electrical steel sheet according to one embodiment of the present invention is {001} represented by the orientation distribution function (ODF). <100> Defense strength is 3.0 or higher, {011} <100> Defense strength is {001} <100> Higher than the defense strength.

[0106] The orientation distribution function (ODF) is a quantitative method for analyzing the grain distribution within a steel sheet. It quantifies the extent to which a specific crystal orientation is distributed within the steel sheet. Orientation strength refers to how strongly a specific crystal orientation is developed compared to a random grain structure.

[0107] In one embodiment of the present invention, the measurement plane of the orientation distribution function (ODF) targets the rolling vertical direction plane (TD plane), and the measurement area is at least 5 mm × 5 mm. In order to reduce errors depending on the measurement position, data for a sufficiently large area must be measured, and the data can be measured for 20 or more specimens and combined for calculation at once.

[0108] The measurement method uses EBSD mounted on an SEM, and can be analyzed using OIM analysis software, and the error angle for orientation can be set to 15°.

[0109] {001} <100> The direction of the crystal is perpendicular to the rolling direction, which makes it easy to magnetize. <100> It has a direction and also has excellent circumferential magnetism, which is the average in all directions. {001} <100> If the defense strength is suppressed, magnetization is difficult. <111> Directions, etc. may develop within the plane, causing deterioration of magnetic properties. More specifically, {001} <100> The defense strength can be 3.0 to 4.5, more specifically 3.1 to 4.0.

[0110]

[0111] {011} <100> The grain size of the direction is {001} <100> Easy to magnetize with <100> Since it has a direction within the plane, it has a favorable effect on magnetism. In one embodiment of the present invention, {011} <100> Defense strength {001} <100> By increasing the strength compared to the defense strength, not only the magnetism but also the magnetic anisotropy is maximized. More specifically, {011} <100> The defense strength may be 3.3 to 5.5, more specifically 3.5 to 5.0. {011} <100> Defense strength is {001} <100> It can be 0.3 to 2.0 higher than the defense strength.

[0112] FIG. 1 schematically illustrates a cross-section of a non-oriented electrical steel sheet (100) according to an embodiment of the present invention. As shown in FIG. 1, the non-oriented electrical steel sheet (100) according to an embodiment of the present invention includes a surface portion (20) extending from the steel sheet surface to a depth of 50 μm inward and a center portion (10), and a ratio of the average grain size in the surface portion (20) to the average grain size in the center portion (10) (surface portion / center portion) may be 0.60 to 0.80. When the grains in the surface portion (20) are smaller than the grains in the center portion (10), hysteresis loss may increase and magnetic permeability may decrease in the surface portion, which may cause deterioration of magnetic properties. When the grains in the surface portion (20) are larger than the grains in the center portion (10), problems may arise in that eddy current loss in the surface portion increases and a texture that is unfavorable to magnetization develops. More specifically, the ratio of the average grain size within the surface portion (20) to the average grain size within the center portion (10) (surface portion / center portion) may be 0.63 to 0.77. The grain size can be obtained by assuming a virtual circle having the same area as the corresponding grains and using the diameter of the circle. It is measured based on the vertical rolling direction plane (TD plane), and the number of grains within the surface portion (20) and the center portion (10) areas is counted to obtain the average area of ​​each grain, and the area can be calculated using a circle having this area. The surface portion (20) within the steel sheet exists as upper and lower portions, and in this case, the grain sizes of the upper surface portion and the lower surface portion can be obtained by taking the average.

[0113] As described above, in one embodiment of the present invention, a specific aggregate structure can be developed to maximize magnetic anisotropy. Specifically, a non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following equation 1.

[0114] [Formula 1]

[0115] B 50L - B 50(55°) ≥ 0.11 T

[0116] (B in Equation 1 50LMagnetic flux density B measured in the rolling direction 50 , B 50(55°) is the magnetic flux density B measured in a direction at an angle of 55° to the rolling direction. 50 )

[0117] Equation 1 represents the difference in magnetic flux density in the rolling direction (RD direction) and in a direction at an angle of 55° to the rolling direction, and a larger difference indicates higher magnetic anisotropy. Specifically, the value of the left side of Equation 1 can be 0.12 to 0.20 T.

[0118] In one embodiment of the present invention, the iron loss (W) of the non-oriented electrical steel sheet 10 / 400 ) may be less than 12.5 W / Kg. Iron loss (W 10 / 400 ) is the iron loss when a magnetic flux density of 1.0 T is induced at a frequency of 400 Hz. More specifically, the iron loss (W) of non-oriented electrical steel sheet 10 / 400 ) may be 10.0 to 12.0 W / kg. In one embodiment of the present invention, the iron loss may be expressed based on a thickness of 0.25 mm.

[0119]

[0120] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention comprises the steps of: hot-rolling a slab to manufacture a hot-rolled steel sheet; preliminarily cold-rolling the hot-rolled steel sheet; a first annealing step of annealing the preliminarily cold-rolled steel sheet; a step of cold-rolling the annealed steel sheet to manufacture a cold-rolled sheet; and a second annealing step of annealing the cold-rolled sheet.

[0121]

[0122] Below, each step is explained in detail.

[0123] First, the slab is hot rolled.

[0124] The alloy composition of the slab has been described in the alloy composition of the previously mentioned non-oriented electrical steel sheet, so a duplicate description will be omitted. Since the alloy composition does not substantially change during the manufacturing process of the non-oriented electrical steel sheet, the alloy composition of the non-oriented electrical steel sheet and the slab are substantially identical.

[0125] Specifically, the slab contains Si: 1.5 to 5.0%, Al: 0.1 to 2.0%, Mn: 0.1 to 2.0% by weight, with the remainder being Fe and unavoidable impurities.

[0126] As other additional elements have been described in the alloy composition of non-oriented electrical steel sheets, redundant descriptions are omitted.

[0127] Slabs can be heated before hot rolling. The heating temperature of the slab is not limited, but the slab can be heated to 1200℃ or lower. If the slab heating temperature is too high, precipitates such as AlN and MnS present within the slab may be re-dissolved and then finely precipitated during hot rolling and annealing, inhibiting grain growth and reducing magnetism.

[0128] Next, the slab is hot-rolled to produce a hot-rolled sheet. The thickness of the hot-rolled sheet can be 1.0 to 4.5 mm. In the step of producing the hot-rolled sheet, the finishing rolling temperature can be 800°C or higher. Specifically, it can be 870 to 950°C. The hot-rolled sheet can be coiled at a temperature of 600°C or higher. More specifically, the thickness of the hot-rolled sheet can be 1.4 to 3.0 mm.

[0129] After manufacturing a hot-rolled steel sheet, subsequent steps can be performed while the scale remaining on the hot-rolled steel sheet remains. That is, after hot rolling, scale removal processes such as pickling, shot blasting, or surface grinding can be omitted, and subsequent steps can be performed. By performing cold rolling without the pickling process, friction between the rolling work rolls and the steel sheet increases, so that shear deformation is simultaneously applied in addition to plane deformation during rolling, and a specific orientation develops during recrystallization annealing. In one embodiment of the present invention, scale refers to a portion on the surface of the steel sheet where elements such as Fe, Al, and Si combine with oxygen to form a phase different from that of the base metal. Remaining scale means that at least 1 μm of scale remains on the hot-rolled sheet. In this case, the scale thickness refers to the sum of the scale thicknesses formed on both surfaces of the steel sheet. If the remaining scale thickness is too thin, the effect due to the scale residue may not be fully exerted. Even if the scale thickness is thicker, the effect is not improved, and there is a problem of a reduced yield of the steel sheet. More specifically, scales with a thickness of 0.1 to 1 μm may remain. Furthermore, pre-cold rolling can be performed without applying heat from the outside of the steel sheet after hot rolling. In other words, hot-rolled sheet annealing can be omitted.

[0130] Next, the hot-rolled steel sheet undergoes preliminary cold rolling. Preliminary cold rolling is distinguished from cold rolling, described later, in that it is the first rolling step in a process that involves rolling to an intermediate thickness, rather than the final product thickness, followed by intermediate annealing and then cold rolling to the final product thickness.

[0131] Preliminary cold rolling can be performed at a reduction ratio of 40 to 79% to improve final cold rolling productivity and grain size in the final product sheet. Furthermore, if rolling productivity is not a consideration, the present invention also allows preliminary cold rolling to be performed in a reverse mill. The preliminarily cold rolled sheet can have a thickness of 0.3 to 1.5 mm. More specifically, the reduction ratio can be 50 to 75% and the thickness can be 0.5 to 1.0 mm.

[0132] The preliminary cold rolling reduction can be calculated as (steel thickness before rolling - steel thickness after rolling) / steel thickness before rolling. If the reduction ratio is too low in the preliminary cold rolling stage, the rolling load increases during the final cold rolling, which reduces productivity and increases the final reduction ratio, which causes fine grains. <111> Problems that promote azimuth re-determination may arise. Conversely, if the reduction ratio is too high, the cold rolling load increases and the possibility of plate fracture increases.

[0133] Next, in the first annealing step, the pre-cold rolled steel sheet is annealed.

[0134] In one embodiment of the present invention, by appropriately controlling the tension in the first annealing step, the grain size of the crystals on the surface and in the center of the steel sheet can be appropriately controlled. If the tension is too small, fine crystals develop on the surface of the steel sheet, and the average grain size of the surface becomes relatively small, {011} <100> By inhibiting the development of orientation, it can have some negative effects on magnetism. If the tension is too high, similar grain growth can occur on the surface and center of the steel plate, which makes the average grain size on the surface relatively large. In this case, random orientation can develop, which can have some negative effects on magnetism. More specifically, 0.10 to 1.00 kgf / mm 2It can be annealed while applying tension. At this time, the tension is the tension measured at the entrance of the annealing furnace, and can be measured by passing the coil to be processed through a roll equipped with a load cell. More specifically, it is 0.25 to 0.75 kgf / mm. 2 It can be annealed while applying tension.

[0135] The first annealing step can be performed at a temperature of 800 to 1100°C for 5 to 20 seconds. If the annealing temperature is too low, the coarse microstructure in the center will not recover sufficiently, resulting in {001} of the final product. <100> If the fracture temperature is too high, fine precipitates may form on the surface, resulting in {011} defects in the final product. <100> The magnetic properties may be poor due to insufficient development of the magnetic field. More specifically, the first annealing step may cause cracking at temperatures between 850 and 1050°C.

[0136] If the soaking time is too short, the surface microstructure may not be sufficiently recrystallized, resulting in surface grains in the final product being excessively smaller than those in the core. If the soaking time is too long, surface grains may grow excessively. More specifically, soaking can last between 7 and 17 seconds.

[0137] Again, returning to the description of the method for manufacturing non-oriented electrical steel sheets, after the first annealing step, the annealed steel sheet is cold rolled to manufacture a cold-rolled sheet.

[0138] In one embodiment of the present invention, cold rolling is performed through three or more passes, and the reduction ratios in the first, second, and third passes may each be 23 to 33%. In one embodiment of the present invention, the number of passes refers to the number of times the steel sheet passes through the work rolls of the rolling mill. Cold rolling may be performed by tandem rolling or reverse rolling, and a combination of these is also possible.

[0139] When the reduction ratio is high, not only the plane strain but also the shear strain applied to the material increases. If the number of passes is the same, the higher the reduction ratio, the more shear strain is applied to the material, resulting in {011} <100> It is easy to develop defense. If the pressure drop per pass is too low {011} <100> It is difficult to expect improvement in magnetic properties because the defense is not sufficiently developed. If the compression ratio per pass is too high, {001} <100> The defense can be suppressed. More specifically, the compression ratio in the first, second, and third passes can be 24 to 30%.

[0140] In addition, during the step of manufacturing a cold rolled sheet, the product of the diameter (mm) of the work roll and the coefficient of friction (μ) between the work roll and the material may be 1.5 to 9.0. If the diameter of the work roll is large, the area where the work roll comes into contact with the material at a given reduction ratio becomes larger, so that a larger shear deformation can be applied, and if the diameter of the work roll is small, the amount of shear deformation is reduced. The coefficient of friction is determined by the roughness of the work roll and the material, the type of rolling oil, etc., and the larger the coefficient of friction under given conditions, the larger the shear deformation can be applied. The coefficient of friction can be measured by the method of the published patent KR1996-0021206.

[0141] If the product of the work roll diameter and the coefficient of friction is large, the amount of shear strain applied to the material increases {011} <100> It can promote the development of defense. If the value is too small, {011} <100> If this is not developed enough, it is difficult to achieve sufficient improvement in magnetic properties, and if the value is too high, {001} <100> The development of can be suppressed. More specifically, the product of the diameter (mm) of the work roll and the coefficient of friction (μ) of the work roll and the material may be 1.8 to 8.8. Specifically, the work roll diameter may be 50 to 150 mm. More specifically, the work roll diameter may be 55 to 100 mm. The coefficient of friction may be 0.02 to 0.13 μ. More specifically, the coefficient of friction may be 0.03 to 0.12 μ. The work roll diameter and the coefficient of friction may be values ​​at the last pass of cold rolling.

[0142] The final rolled thickness can be from 0.1 mm to 0.35 mm.

[0143] Next, in the second annealing step, the cold-rolled sheet is annealed. The second annealing step can be performed at 900°C or higher. If the soaking temperature is too low, the grains may not grow sufficiently, which may lead to increased hysteresis loss and deterioration of iron loss. More specifically, the annealing can be performed at a temperature of 900 to 1050°C. The second annealing step can be performed for 50 to 120 seconds. The dew point may be -10°C or lower.

[0144] During the cold-rolled sheet annealing process, all (i.e., more than 99%) of the processed structure formed during the cold rolling stage can be recrystallized.

[0145] After cold-rolled sheet annealing, an insulating film can be formed. The insulating film can be treated with organic, inorganic, or organic-inorganic composite films, and can also be treated with other insulating film agents.

[0146]

[0147] The present invention will be described in more detail below through examples. However, these examples are intended only to illustrate the present invention and are not intended to limit the present invention.

[0148]

[0149] Example 1

[0150] A slab was manufactured using the components listed in Table 1 and containing the remainder Fe and unavoidable impurities. This was heated to 1150°C and hot-rolled at a finishing temperature of 950°C to manufacture a hot-rolled sheet having the thickness listed in Table 3 below.

[0151] Afterwards, the hot-rolled steel sheet was preliminarily cold-rolled to the thickness shown in Table 2 below without annealing, and then annealed for the first time under the conditions shown in Table 2, and then cold-rolled under the conditions shown in Table 2 below to obtain a final thickness of 0.25 mm. The cold-rolled steel sheet was annealed for the second time at a dew point of -20°C and a soaking temperature of 1000°C for 100 seconds.

[0152] In order to analyze the texture of the manufactured non-oriented electrical steel sheet, 30 specimens measuring 10 mm × 20 mm were cut for each specimen, mounted in three sets of 10 specimens each so that the observation surface was the TD plane, and the observation surface was polished to a mirror-like surface without scratches. The EBSD measurement applied the conditions of 5000 μm in height, approximately 2500 μm in width (including all 10 0.25 mm specimens), and 1 μm in step size. The three sets of measurement data were merged using the merging function of the OIM software to calculate the ODF at once, and the results are shown in Table 4.

[0153] Magnetic properties such as magnetic flux density and iron loss were measured by cutting 60 mm wide × 60 mm long × 5 sheets of each specimen into single sheet tester and measuring the magnetic flux density in the rolling direction and 55° direction and displaying the results. Iron loss was measured in the rolling direction and the direction perpendicular to the rolling and displayed as the average. At this time, W 10 / 400is the iron loss when a magnetic flux density of 1.0 T is induced at a frequency of 400 Hz, and B50 refers to the magnetic flux density induced in a magnetic field of 5000 A / m.

[0154] Specimen numberSiAlMnCSNTiNbV[%][%][%][ppm][ppm][ppm][ppm][ppm][ppm]A12.701.60.7281416111915A22.701.60.728131323 1721A32.701.60.720181824819A42.701.60.7131817171810A52.701.60.7171614141616A62.701.60.7244317171714A72 .701.60.7261313111313A82.701.60.7141416141418B13.300.61.6137314121123B23.300.61.63513159139B33.300.61 .616329241910B43.300.61.6172012142021B53.300.61.6131313171318B63.300.61.6281716141715B73.300.61.629421 4131817B83.300.61.6311318181313C13.750.21.668199241920C23.750.21.6211611212316C33.750.21.629171223141 2C43.750.21.62188171818C53.750.21.631451391411C63.750.21.6281516131512C73.750.21.625171671715C83.750.2 1.6274217141418D14.200.50.22298118923D24.200.50.2171611121611D34.200.50.2143510122113D44.200.50.291614 141614D54.200.50.2161716161717D64.200.50.2213320151821D74.200.50.2161720101724D84.200.50.2311312131313

[0155] Specimen number Hot rolled plate Thickness Thickness after preliminary cold rolling 1st annealing cracking temperature 1st annealing cracking 1st annealing tension [mm] [mm] [℃] Time [sec] [kgf / mm 2 ]A12.080.73850300.70A22.080.7395070.70A32.080.73100070.70A42.720.95105070.70 A52.080.7385070.30A62.080.7395070.30A72.080.73100070.30A82.080.73105070.30B1 1.840.64850170.30B21.840.64950171.20B31.400.491000170.30B41.840.641150170.30 B51.840.64850170.50B61.840.64950170.50B71.840.641000170.50B81.840.641050170. 50C11.630.57850120.30C21.630.57750120.30C31.630.57850120.05C41.630.5785030.3 0C51.630.57850120.70C61.630.57850120.70C71.630.57850120.70C81.630.57850120.7 0D12.080.73950100.80D22.080.73950100.80D32.080.73950100.80D42.080.73950100.8 0D52.080.73950100.50D62.080.73950100.50D72.080.73950100.50D82.080.73950100.50

[0156] Specimen numberCold rolled 1-pass reduction rateCold rolled 2-pass reduction rateCold rolled 3-pass reduction rateWR diameter [mm]Friction coefficientWR diameter × friction coefficient[%][%][%]A1303030600.031.8A2303030800.1411.2A3303030450.031.4A4363636800.032.4A5303030600.074.2A6303030800.075.6A7303030600.074.2A8303030 800.075.6B1272727600.053.0B2272727800.054.0B3202020600.053.0B427272780 0.054.0B5272727600.116.6B6272727800.118.8B7272727600.116.6B8272727800. 118.8C1242424800.032.4C2242424600.031.8C3242424800.032.4C4242424600.0 31.8C5242424800.075.6C6242424600.074.2C7242424800.075.6C8242424600.074 .2D1303030800.054.0D23030302100.0510.5D3303030800.010.8D4303030600.053 .0D5303030800.118.8D6303030600.116.6D7303030800.118.8D8303030600.116.6

[0157] Psalm number {001} <100> {011} <100> Surface / CenterSurface / Center Directional Strength Directional Strength Grain Size Grain Size [㎛] [㎛] A13.52.272780.92 A22.13.752720.72 A33.22.256830.67 A42.23.555840.65 A53.33.761790.77 A63.33.753820.65 A73.1 4.064840.76A83.43.658770.75B13.62.277810.95B23.62.376850.89B33.52.05 3770.69B43.32.160790.76B53.74.258770.75B63.54.855820.67B73.44.356790. 71B83.24.260830.72C13.32.476810.94C22.03.761840.73C33.72.141830.49C4 3.61.939780.50C53.74.058760.76C63.24.252800.65C73.23.756810.69C83.43. 853830.64D13.22.571760.93D22.23.654760.71D33.42.360790.76D43.53.9538 10.65D53.24.255770.71D63.44.652750.69D73.34.256790.71D83.54.552760.68

[0158] Specimen numberW10 / 400(W / kg)B50(RD)B50(55˚)ΔB50[T][T][T]A112.81.691.590.10A212.61.691.59 0.10A312.91.691.600.09A412.51.691.590.10A511.51.721.590.13A611.41.721.580.14A7 11.51.721.590.13A811.61.721.590.13B112.61.691.600.09B212.61.691.590.10B312.51 .691.590.10B412.71.691.590.10B511.61.721.590.13B611.41.721.590.13B711.41.721.5 90.13B811.51.721.580.14C112.61.691.590.10C212.71.691.590.10C312.51.691.590.10 C412.71.691.590.10C511.51.721.590.13C611.61.721.590.13C711.41.721.590.13C811.7 1.721.590.13D112.61.691.590.10D212.81.691.590.10D312.81.691.600.09D411.71.721. 580.14D511.51.721.590.13D611.41.721.590.13D711.41.721.590.13D811.61.721.590.13

[0159]

[0160] As shown in Tables 1 to 5, it can be confirmed that the invention examples in which the steel components are appropriately controlled, the process conditions are appropriately controlled, and the aggregate structure is appropriately controlled have excellent iron loss and magnetic flux density, and at the same time, the magnetic anisotropy is maximized.

[0161] On the other hand, if the steel component is not properly controlled or the process conditions are not properly controlled, and the aggregate structure is not properly formed, it can be confirmed that the iron loss and magnetic flux density are inferior or the magnetic anisotropy cannot be sufficiently obtained.

[0162]

[0163] The present invention is not limited to the embodiments described herein, but can be manufactured in a variety of different forms. Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

[0164] [Explanation of symbols]

[0165] 100: Non-oriented electrical steel sheet 10: Center

[0166] 20: Surface area

Claims

1. Contains Si: 1.5 to 5.0% by weight, Al: 0.1 to 2.0%, Mn: 0.1 to 2.0%, and the remainder includes Fe and inevitable impurities. {001} represented by the orientation distribution function (ODF) <100> Defense strength is 3.0 or higher, {011} <100> Defense strength is {001} <100> Non-oriented electrical steel sheet with higher strength than the defense strength.

2. In paragraph 1, The above non-oriented electrical steel sheet includes a surface portion and a center portion from the surface of the steel sheet to a depth of 50 μm in the inner direction, A non-oriented electrical steel sheet having a ratio of the average grain size within the surface portion to the average grain size within the center portion of 0.6 to 0.

8.

3. In paragraph 1, Non-oriented electrical steel sheet further comprising at least one of P: 0.1 wt% or less (excluding 0%), C: 0.005 wt% or less (excluding 0%), S: 0.005 wt% or less (excluding 0%), Ti: 0.005 wt% or less (excluding 0%), and N: 0.005 wt% or less (excluding 0%).

4. In paragraph 1, A non-oriented electrical steel sheet further comprising 0.005 to 0.200 wt% of each or a combined amount of one or more of Sn, Sb, Bi, Pb, Ge and As.

5. In paragraph 1, A non-oriented electrical steel sheet further comprising at least one of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less (excluding 0%), Zn: 0.01 wt% or less (excluding 0%), and Co: 0.05 wt% or less (excluding 0%).

6. In paragraph 1, Non-oriented electrical steel sheet further comprising at least one of Mo: 0.03 wt% or less (excluding 0%), B: 0.0050 wt% or less (excluding 0%), V: 0.0050 wt% or less (excluding 0%), Ca: 0.0050 wt% or less (excluding 0%), Nb: 0.0050 wt% or less (excluding 0%), Zr: 0.005 wt% or less (excluding 0%), Te: 0.01 wt% or less (excluding 0%), and Mg: 0.0050 wt% or less (excluding 0%).

7. In paragraph 1, A non-oriented electrical steel sheet satisfying the following equation 1. [Formula 1] B 50L - B 50(55°) ≥ 0.11 T (B in Equation 1 50L B is the magnetic flux density measured in the rolling direction 50 , B 50(55°) is the magnetic flux density B measured in a direction at an angle of 55° to the rolling direction. 50 ) 8. A step of manufacturing a hot-rolled steel sheet by hot-rolling a slab containing Si: 1.5 to 5.0% by weight, Al: 0.1 to 2.0%, Mn: 0.1 to 2.0% by weight, and the remainder being Fe and unavoidable impurities; A step of preliminarily cold rolling the above hot-rolled steel plate; A first annealing step for annealing a cold-rolled steel sheet; A step for manufacturing cold rolled steel sheets by cold rolling an annealed steel sheet, and A second annealing step for annealing the above cold rolled sheet; Including, In the step of manufacturing the above cold rolled plate, cold rolling is performed through three or more passes, A method for manufacturing a non-oriented electrical steel sheet having reduction ratios of 23 to 33% in the first, second, and third passes, respectively.

9. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further includes at least one of P: 0.1 wt% or less (excluding 0%), C: 0.005 wt% or less (excluding 0%), S: 0.005 wt% or less (excluding 0%), Ti: 0.005 wt% or less (excluding 0%), and N: 0.005 wt% or less (excluding 0%).

10. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further contains 0.005 to 0.200 wt% of each or a combined amount of one or more of Sn, Sb, Bi, Pb, Ge and As.

11. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further includes at least one of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less (excluding 0%), Zn: 0.01 wt% or less (excluding 0%), and Co: 0.05 wt% or less (excluding 0%).

12. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further includes at least one of Mo: 0.03 wt% or less (excluding 0%), B: 0.0050 wt% or less (excluding 0%), V: 0.0050 wt% or less (excluding 0%), Ca: 0.0050 wt% or less (excluding 0%), Nb: 0.0050 wt% or less (excluding 0%), Zr: 0.005 wt% or less (excluding 0%), Te: 0.01 wt% or less (excluding 0%), and Mg: 0.0050 wt% or less (excluding 0%).

13. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the subsequent steps are performed while the scale remaining on the hot-rolled steel sheet remains after manufacturing the hot-rolled steel sheet.

14. In paragraph 8, In the first annealing step, 0.1 to 1.0 kgf / mm 2A method for manufacturing a non-oriented electrical steel sheet by annealing while applying tension.

15. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet in which the first annealing step is performed at a temperature of 800 to 1100°C for 5 to 20 seconds.

16. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the product of the diameter (mm) of the work roll and the coefficient of friction (μ) between the work roll and the material is 1.5 to 9.0 during the step of manufacturing the cold rolled sheet.

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