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 contains, in wt%, 1.5-5.0% of Si, 0.1-2.0% of Al, and 0.1-2.0% of Mn, with the remainder comprising Fe and inevitable impurities, and satisfies Expression 1 below. [Expression 1] V{001}<001> / V{011}<001> ≤ 0.65 (In Expression 1, V{001}<001> represents the fraction of crystal grains having an orientation within 15° of {001}<001>, and V{011}<001> represents the fraction of crystal grains having an orientation within 15° of {011}<001>.)

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 a specific aggregate structure is developed through heating, first cracking, second cracking, and cooling processes in an annealing process following preliminary cold rolling, thereby maximizing 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 45° 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 a specific aggregate structure is developed through heating, first cracking, second cracking, and cooling processes in an annealing process following preliminary cold rolling, thereby maximizing magnetic anisotropy.

[0007] 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%, the remainder being Fe and unavoidable impurities, and satisfies the following formula 1.

[0008] [Formula 1]

[0009] V{001} <001> / V{011} <001> ≤ 0.65

[0010] (V{001} in Equation 1 <001> Silver {001} <001> It represents the fraction of crystal grains having an orientation within 15° from V{011} <001> Silver {011} <001> ) represents the fraction of crystal grains having an orientation within 15° from the center.

[0011] A non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following equation 2.

[0012] [Formula 2]

[0013] (V{100} <001> + V{100} <031> + V{100} <110> ) / ( V{111} <112> + V{111} <011> ) ≥ 1.3

[0014] (V{100} in Equation 2 <001> Silver {100} <001> It represents the fraction of crystal grains having an orientation within 15° from V{100} <031> Silver {100} <031> It represents the fraction of crystal grains having an orientation within 15° from V{100} <110> Silver {100} <110> It represents the fraction of crystal grains having an orientation within 15° from V{111} <112> Silver {111} <112> It represents the fraction of crystal grains having an orientation within 15° from V{111} <011> Silver {111} <011> ) represents the fraction of crystal grains having an orientation within 15° from the center.

[0015] 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%).

[0016] 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.

[0017] 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%).

[0018] 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%).

[0019] A non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following equation 3.

[0020] [Formula 3]

[0021] B 50L - B 50D ≥ 0.08 T

[0022] (B in Equation 3 50L Magnetic flux density B measured in the rolling direction 50 , B 50D is the magnetic flux density B measured in a direction at a 45° angle to the rolling direction. 50 )

[0023] A non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following equation 4.

[0024] [Formula 4]

[0025] B 50c - B 50D ≥ 0.03 T

[0026] (B in Equation 4 50CMagnetic flux density B measured in the direction perpendicular to the rolling 50 , B 50D is the magnetic flux density B measured in a direction at a 45° angle to the rolling direction. 50 )

[0027] A non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following equation 5.

[0028] [Formula 5]

[0029] (B 50L + B 50C ) / 2 ≥ 1.68 T

[0030] (B in Equation 5 50L Magnetic flux density B measured in the rolling direction 50 , B 50C is the magnetic flux density B measured in the vertical direction of the rolling 50 )

[0031] 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.

[0032] The first annealing step includes a step of heating the cold-rolled sheet from 40°C to a first cracking temperature (T1) at 10 to 50°C / s; a first cracking step of cracking the cold-rolled sheet at a first cracking temperature (T1) of 950 to 1100°C; a second cracking step of cracking the cold-rolled sheet at a second cracking temperature (T2) of 800 to 950°C; and a cooling step of cooling from the second cracking temperature (T2) to 670°C for 10 to 40 seconds.

[0033] 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%).

[0034] 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.

[0035] 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%).

[0036] 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%).

[0037] After manufacturing a hot-rolled steel sheet, subsequent steps can be performed while the scale remaining on the hot-rolled steel sheet remains.

[0038] The reduction ratio in the preliminary cold rolling stage can be 40 to 79%.

[0039] The cracking time of the first cracking stage can be 20 to 60 seconds.

[0040] After the first cracking step, a step of cooling to a second cracking temperature at a cooling rate of 1 to 20°C / s may be further included.

[0041] The cracking time of the second cracking stage can be 40 to 100 seconds.

[0042]

[0043] 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.

[0044] 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 only 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.

[0045] 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.

[0046] 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.

[0047] Also, unless otherwise stated, % means weight%, and 1 ppm is 0.0001 weight%.

[0048] 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.

[0049] 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.

[0050] 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.

[0051]

[0052] 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.

[0053] Below, the reasons for the limitation of the components of non-oriented electrical steel sheets are explained.

[0054]

[0055] Si: 1.5 to 5.0 wt%

[0056] Silicon (Si) increases the resistivity of the material, thereby reducing iron loss, and increases 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, which drastically reduces rolling productivity and may form a surface oxide layer and oxides that are harmful 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%.

[0057]

[0058] Al: 0.1 to 2.0 wt%

[0059] 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 0.3 to 1.9 wt%. More specifically, it may be included in an amount of 0.6 to 1.5 wt%.

[0060]

[0061] Mn: 0.1 to 2.0 wt%

[0062] 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 0.2 to 1.6 wt%. More specifically, it may be included in an amount of 0.3 to 1.4 wt%.

[0063]

[0064] 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%).

[0065] P: 0.1 wt% or less

[0066] 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%.

[0067] C: 0.005 wt% or less

[0068] 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 0.003 wt%.

[0069] S: 0.005 wt% or less

[0070] Sulfur (S) can form fine precipitates, MnS and CuS, which can worsen magnetic properties and hot workability. More specifically, S can be included in an amount of 0.0001 to 0.0030 wt%.

[0071] Ti: 0.005 wt% or less

[0072] 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 parent material, thereby inhibiting grain growth and domain wall migration. More specifically, Ti may be included in an amount of 0.0001 to 0.0030 wt%.

[0073] N: 0.005 wt% or less

[0074] 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 0.0030 wt%.

[0075]

[0076] 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.

[0077] Sn

[0078] 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 fracture of cold-rolled sheets 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%.

[0079] Sb

[0080] Antimony (Sb) can be additionally added to improve magnetism, as it improves the material's aggregate structure 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%.

[0081] Bi, Pb, Ge, and As

[0082] 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.

[0083]

[0084] 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%).

[0085] Cu: 0.005 to 0.200 wt%

[0086] 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%.

[0087] Cr: 0.01 to 0.50 wt%

[0088] 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%.

[0089] Ni: 0.05 wt% or less

[0090] 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.

[0091] Zn: 0.01 wt% or less

[0092] 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%.

[0093] Co: 0.05 wt% or less

[0094] 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.

[0095]

[0096] 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%).

[0097] Mo: 0.030 wt% or less

[0098] 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%.

[0099] B: 0.0050 wt% or less

[0100] 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%.

[0101] V: 0.0050 wt% or less

[0102] 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%.

[0103] Ca: 0.0050 wt% or less

[0104] 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.

[0105] Nb: 0.0050 wt% or less

[0106] 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%.

[0107] Zr: 0.0050 wt% or less

[0108] 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%.

[0109] Te: 0.0100 wt% or less

[0110] 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%.

[0111] Mg: 0.0050 wt% or less

[0112] 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%.

[0113]

[0114] 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).

[0115]

[0116] As described above, in one embodiment of the present invention, by appropriately controlling the alloy composition of the steel plate and annealing through an appropriate process in the annealing process after preliminary cold rolling, a specific aggregate structure can be developed, thereby maximizing magnetic anisotropy.

[0117] Specifically, a non-oriented electrical steel sheet according to one embodiment of the present invention satisfies the following equation 1.

[0118] [Formula 1]

[0119] V{001} <001> / V{011} <001> ≤ 0.65

[0120] (V{001} in Equation 1 <001> Silver {001} <001> It represents the fraction of crystal grains having an orientation within 15° from V{011} <001> Silver {011} <001> ) represents the fraction of crystal grains having an orientation within 15° from the center.

[0121] {001} <001> The texture is an Exact Cube texture, which is a desirable texture for non-oriented electrical steel sheets, {011} <001> The texture is known to be an Exact Goss texture, which is desirable for grain-oriented electrical steel sheets. In one embodiment of the present invention, unlike conventional non-oriented electrical steel sheets, the ratio of Exact Cube is lowered compared to Exact Goss, thereby maximizing magnetic anisotropy. However, a problem may arise in that anisotropy is improved when the value on the left side of Equation 1 is small. More specifically, the value on the left side of Equation 1 may be 0.30 to 0.64.

[0122] In one embodiment of the present invention, the grain size fraction can be measured through EBSD. More specifically, the TD surface of the non-oriented electrical steel sheet is measured at a distance of 0.5 to 2 mm. 2 It is manufactured from specimens of the same width and can be measured from at least eight specimens.

[0123] In addition, a non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following equation 2.

[0124] [Formula 2]

[0125] (V{100} <001> + V{100} <031> + V{100} <110> ) / ( V{111} <112> + V{111} <011> ) ≥ 1.30

[0126] {100} <001> , {100} <031> , {100} <110> The assembly structure is a Rotated Cube assembly structure, which is advantageous for securing magnetic flux density and iron loss characteristics, and {111} <112> , {111} <011> The texture is known to be unfavorable for magnetic flux density and iron loss. In one embodiment of the present invention, the fraction of {111} planes was suppressed, similar to the conventional non-oriented electrical steel sheet, to maximize magnetic anisotropy. If the value on the left side of Equation 2 is too small, deterioration of magnetic flux density and iron loss may occur. More specifically, the value on the left side of Equation 2 may be 1.3 to 2.3.

[0127]

[0128] 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 3.

[0129] [Formula 3]

[0130] B 50L - B 50D ≥ 0.08 T

[0131] (B in Equation 3 50L Magnetic flux density B measured in the rolling direction 50 , B 50D is the magnetic flux density B measured in a direction at a 45° angle to the rolling direction. 50 )

[0132] Equation 3 represents the difference in magnetic flux density in the rolling direction (RD direction) and in a direction at a 45° angle with the rolling direction. A larger difference indicates higher magnetic anisotropy. Specifically, the value of the left side of Equation 3 can be 0.08 to 0.13 T.

[0133] A non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following equation 4.

[0134] [Formula 4]

[0135] B 50c - B 50D ≥ 0.03 T

[0136] (B in Equation 4 50C Magnetic flux density B measured in the direction perpendicular to the rolling 50 , B 50D is the magnetic flux density B measured in a direction at a 45° angle to the rolling direction. 50 )

[0137] Equation 4 represents the difference in magnetic flux density in the direction perpendicular to the rolling direction (TD direction) and in the direction at a 45° angle to the rolling direction. A larger difference indicates a higher magnetic anisotropy. Specifically, the value on the left side of Equation 4 can be 0.03 to 0.06 T.

[0138] A non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following equation 5.

[0139] [Formula 5]

[0140] (B 50L + B 50C ) / 2 ≥ 1.680 T

[0141] (B in Equation 5 50L Magnetic flux density B measured in the rolling direction 50 , B 50C is the magnetic flux density B measured in the vertical direction of the rolling 50 )

[0142] Equation 5 represents the average magnetic flux density in the rolling direction and the direction perpendicular to the rolling direction, with a higher value being more advantageous. More specifically, the value on the left side of Equation 5 can be between 1.680 and 1.770 T.

[0143] As described above, in one embodiment of the present invention, the core loss (W) of the non-oriented electrical steel sheet based on a thickness of 0.25 mm 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.

[0144]

[0145] 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.

[0146]

[0147] Below, each step is explained in detail.

[0148] First, the slab is hot rolled.

[0149] 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.

[0150] 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.

[0151] As other additional elements have been described in the alloy composition of non-oriented electrical steel sheets, redundant descriptions are omitted.

[0152] 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.

[0153] 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 1.5 to 4.3 mm.

[0154] 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 ㎛ may remain. In addition, preliminary cold rolling can be performed as is without applying heat from the outside of the steel sheet after hot rolling.

[0155] 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.

[0156] 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 0.6 to 1.3 mm.

[0157] The preliminary cold rolling reduction ratio can be calculated as (steel plate thickness before rolling - steel plate thickness after rolling) / steel plate thickness before rolling × 100(%). 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 <111> / ND This can lead to problems that promote directional recrystallization. Conversely, if the reduction ratio is too high, the cold rolling load increases and the possibility of plate fracture increases.

[0158] The pre-cold rolling step can be performed at a temperature of 60 to 300°C. This temperature can be raised naturally by friction between the steel sheet and the rolling rolls, or by external heating. If the temperature is too low, the rolling load increases significantly, and the steel sheet may slip between the rolling rolls instead of being rolled, resulting in problems such as twisting. If the temperature is too high, a thick oxide layer may form on the steel sheet surface, which can deteriorate magnetism and cause problems such as ignition of the rolling oil. More specifically, it is preferably performed at a temperature of 70 to 250°C. The aforementioned temperature refers to the temperature of the steel sheet.

[0159] As mentioned above, the preliminary cold rolling step can be omitted if necessary.

[0160] Next, in the first annealing step, the pre-cold-rolled steel sheet is annealed. In one embodiment of the present invention, in the first annealing step, a specific aggregate structure is developed through heating, first cracking, second cracking, and cooling processes, thereby maximizing magnetic anisotropy.

[0161] First, the cold-rolled sheet is heated from 40°C to the first cracking temperature (T1) at a rate of 10 to 50°C / s. At this time, if the heating rate is too slow, a problem may arise in which a texture having {111} planes develops. Conversely, if the heating rate is too fast, temperature control may be difficult, making it difficult to control the target sheet temperature. More specifically, heating may be performed at a rate of 15 to 30°C / s. In one embodiment of the present invention, the temperature reference is the surface temperature of the steel sheet.

[0162] Next, the cold-rolled sheet is cracked at a first cracking temperature (T1) of 950 to 1100°C. The first cracking temperature (T1) is an arbitrary temperature selected from the range of 950 to 1100°C, and cracking means that the temperature is maintained at ±10°C or less. If the first cracking temperature is too low, a problem of deterioration of iron loss may occur. If the first cracking temperature is too high, a problem of deterioration of magnetic flux density and iron loss may occur. More specifically, cracking may occur at a first cracking temperature (T1) of 950 to 1050°C. The cracking time of the first cracking step may be 20 to 60 seconds.

[0163] After the first cracking step, cooling can be performed to the second cracking temperature at a cooling rate of 1 to 30°C / s. By appropriately adjusting the cooling rate, residual stress in the steel plate can be removed. More specifically, the cooling rate can be adjusted to 5 to 20°C / s.

[0164] Next, the cold-rolled sheet is cracked at a second cracking temperature (T2) of 800 to 950°C. The second cracking temperature (T2) is an arbitrary temperature selected from the range of 800 to 950°C and may be lower than the first cracking temperature (T1). In this way, performing the cracking in two stages can be advantageous in that it can form an appropriate texture while effectively reducing the cooling rate in continuous annealing. If the second cracking temperature is too low, the cooling rate may increase between the first and second cracks, which may cause residual stress to occur and deteriorate the magnetism. If the second cracking temperature is too high, there is a problem in that the cooling rate cannot be effectively reduced during cooling. More specifically, cracking may be performed at a second cracking temperature (T2) of 800 to 950°C. The cracking time of the second cracking stage may be 1 to 30 seconds, and more specifically, 5 to 20 seconds.

[0165] Next, cool from the second cracking temperature (T2) to 670°C for 10 to 40 seconds. At this time, if the cooling time is too short, the problem of magnetism deteriorating due to an increase in residual stress caused by rapid cooling may occur. Conversely, if the cooling time is too long, the problem of magnetism deteriorating due to the micro-precipitation of TiNb(C,N)-based precipitates may occur. More specifically, the cooling can be performed for 15 to 30 seconds.

[0166] 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 produce a cold rolled sheet. At this time, cold rolling can be performed at a reduction ratio of 55 to 70%. If the reduction ratio is too low, the accumulated strain energy in the rolled steel sheet is small, making it difficult to recrystallize in the subsequent annealing process, and the rolled structure remains, which may cause problems in improving the magnetic flux density and iron loss. On the other hand, if the reduction ratio is too high, it may cause problems in the subsequent annealing process. <111> / ND The recrystallization of the grains in the direction of the direction can be promoted, and the grains can become finer, which can cause problems such as poor magnetic flux density and increased iron loss. More specifically, the reduction ratio can be 58 to 67%. The cold rolling step can be performed using a tandem cold rolling mill that continuously cold rolls the steel sheet using multiple rolling stands, or a reverse rolling mill that discontinuously cold rolls the steel sheet using 12 or more rolling rolls. The final rolled thickness can be 0.1 mm to 0.35 mm.

[0167] Next, in the second annealing stage, the cold-rolled sheet is annealed. The second annealing stage can be performed at temperatures above 900°C. If the soaking temperature is too low, grain growth may not be sufficient, resulting in increased hysteresis loss and deterioration of iron loss. More specifically, annealing can be performed at temperatures ranging from 900 to 1050°C. The second annealing stage can be performed for 50 to 120 seconds.

[0168] 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.

[0169] 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.

[0170]

[0171] 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.

[0172]

[0173] Example 1

[0174] A slab was manufactured using the components shown in Table 1, Table 2, and the remainder including 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 a thickness of 2.3 mm.

[0175] Afterwards, the hot-rolled steel sheet was subjected to preliminary cold rolling at a reduction ratio of 65% without annealing, and was subjected to a first annealing under the conditions in Table 3, and then cold rolled to obtain a final thickness of 0.25 mm. The cold-rolled steel sheet was subjected to a second annealing under the conditions in Table 3.

[0176] The TD plane of the manufactured non-oriented electrical steel sheet was analyzed by EBSD, and the results are shown in Table 4.

[0177] The magnetic flux density (B50) and iron loss (W10 / 400) were measured by the Epstein measurement method by adjusting the number of Epstein specimens processed to the size of 305 mm × 30 mm in the rolling direction, the rolling vertical direction, and the direction at a 45° angle to the rolling direction so that the weight of each Epstein specimen in the rolling direction, the rolling vertical direction, and the direction at a 45° angle to the rolling direction was 400 to 450 g. At this time, W 10 / 400 The average of the values ​​measured in the rolling direction and the direction perpendicular to the rolling was used.

[0178] At this time, W 10 / 400 is the iron loss when a magnetic flux density of 1.0 T is induced at a frequency of 400 Hz. B 50 refers to the magnetic flux density induced in a magnetic field of 5000 A / m.

[0179] Steel grade (weight %)SiAlMnPSnSb13.61.101.400.0070.08-22.91.400.200.0040.080.0233.80.600.700.0070.050.0343.31.700.100.0060.030.0453.51.001.000.009-0.0563.61.000.100.0020.080.0273.11.101.200.002-0.0483.30.501.100.0090.060.0493.42.000.100.009-0.04103.3 1.300.200.0040.06-113.22.000.500.0070.020.03123.41.800.100.0040.050.03133.60.701.300.0070.040.02143.60.900.600.0100.060.01153.51.801.400.0030.050.02162.91.700.900.0020.040.03171.30.600.600.0040.060.07185.31.000.200.0020.040.05193.50.050. 400.0070.030.02203.52.300.200.0080.010.07213.01.100.050.0010.010.04223.61.102.300.0050.020.05232.91.501.00-0.030.03243.11.501.300.1370.040.08253.21.900.500.005-0.01263.21.700.500.0090.100.03272.71.301.300.0030.03-282.42.001.300.0010.080 .10293.21.801.400.0030.030.03303.30.800.900.0090.010.06313.51.300.400.0020.010.08322.52.001.300.0060.040.08333.31.000.900.0070.040.03343.41.900.400.0020.020.08352.51.601.200.0010.020.08362.31.900.900.0010.030.03373.21.600.700.0020.010.07

[0180] Steel grade (weight%)CNSTiAdditional elements (Cr, Cu, Mo, Bi, Pb, B, V, etc.) 10.00100.00280.00110.0023 20.00220.00250.00210.0028Cu 0.02030.00250.00210.00280.0010Cu 0.05040.00140.00160.00120.0010Zn 0.000550.00220.00280.00250.0013Zn 0.00160.00260.00100.00130.0020Co 0.02070.00280.00100.00190.0024Ni 0.03080.00290.00120.00290.0010Ni 0.05090.00100.00250.00110.0016Bi 0.005100.00250.00140.00120.0022Bi 0.007110.00230.00290.00250.0012Pb 0.005120.00160.00120.00290.0023Pb 0.007130.00260.00230.00300.0023Ge 0.005140.00260.00150.00170.0026Ge 0.007150.00210.00260.00290.0029Cr 0.020160.00220.00150.00220.0015Cr 0.050170.00290.00190.00170.0029-180.00190.00260.00130.0030-190.00280.00280.00290.0023-200.00230.00210.00200.0025-210.00240.00260.00120.0027-220.00110.00300.00160.0023-230.00120.00250.00220.0014-240.00170.00200.00250. 0019-250.00260.00240.00210.0019-260.00200.00210.00230.0022-270.00270.00200.00170.0028-280.00200.00200.00110.0029-290.00110.00110.00190.0010-300.00280.00250.00200.0012-310.00220.00210.00180.0018-320.00220.00110.00290.0015-330.00180.00130.00110.0028-340.00230.00220.00210.0021-350.00170.00200.00210.0023-360.00270.00210.00100.0011-370.00110.00160.00200.0011-.

[0181] Steel grade heating rate (℃ / s)First cracking temperature (℃)Cooling rate after first cracking (℃ / s)Second cracking temperature (℃)Cooling time (sec)12410301391040221103012880283201050158502541810303910305331050158902362197098101372310403870338471050129002393410503950 131041103013820191140970108503312341000589022133795020930111445101018950211544104018840221632100098802517311080199302418Cold rolling not possible19121090178502520Cold rolling not possible21281020128703922Cold rolling Unable23229501591010242910305940252523970189402726239903890372732103068101828369504890392951010138001430701060198801031129002820263210115018850143313110030880153413107016770133548980698025361710402820537461080294050

[0182] Steel formula 1 value formula 2 value B50L(Tesla) B50C(Tesla) B50D(Tesla) 10.581.81.741.671.6220.491.51.771.711.6730.531.61.771.711.6640.381.41.741.671.6450.611.71.751.661.6260.511.81.761.681.6570.541.51.761.681.6580.641.31.781.701.66 90.551.61.721.661.62100.491.61.761.691.66110.571.91.721.671.63120.602.11.731.671.64130.621.41.761.691.65140.582.01.761.701.66150.461.81.701.631.59160.381.91.741.651.62170.721.11.801.721.7418Cold rolled Not available 190.820.81.761.641.6920 Not available for cold rolling 210.720.71.651.611.5922 Not available for cold rolling 230.601.31.721.671.64240.551.51.711.661.63250.591.51.711.651.62260.611.41.711.661.63270.581.61.721.661.63280.631.51.711.651.62290.500.41.651.601.59301.201.4 1.661.621.59310.801.41.631.591.59321.200.51.611.551.55330.561.51.711.671.63340.501.21.701.631.60350.481.11.691.631.63360.501.21.691.631.60370.601.11.681.621.59

[0183] Steel type Formula 3 Value Formula 4 Value Formula 5 Value Iron loss W10 / 400 (W / kg) Remarks 10.120.05 1.70 5 10.8 Invention example 20.100.04 1.74 0 11.7 Invention example 30.110.05 1.74 0 11.9 Invention example 40.100.03 1.70 5 11.9 Invention example 50.130.04 1.70 5 12.0 Invention example 60.110.03 1.72 0 11.7 Invention example 70.110.03 1.72 0 11.8 Invention example 80.120.04 1.74 0 11.9 Invention example 90.100.04 1.69 0 11.5 Invention Example 100.100.031.72511.7 Invention Example 110.090.041.69510.9 Invention Example 120.090.031.70011.3 Invention Example 130.110.041.72511.5 Invention Example 140.100.041.73011.0 Invention Example 150.110.041.66511.4 Invention Example 160.120.031.69511.5 Invention Example 170.06-0.021.76018.7 Comparative Example 18 Cold Rolling Not possible Comparative Example 190.07-0.05 1.70 0 14.2 Comparative Example 20 Cold rolling Not possible Comparative Example 210.06 0.02 1.63 0 13.2 Comparative Example 22 Cold rolling Not possible Comparative Example 230.08 0.03 1.69 5 11.80 Invention Example 240.08 0.03 1.68 5 12.10 Invention Example 250.09 0.03 1.68 0 12.30 Invention Example 260.08 0.03 1.68 5 11.80 Invention Example 270.09 0.03 1.69 0 12.00 Invention Example 280.09 0.03 1.68 0 11.70 Invention Example 290.06 0.01 1.62 5 12.20 Comparative Example 300.07 0.0 31.64012.60Comparative Example 310.040.001.61012.80Comparative Example 320.060.001.58012.10Comparative Example 330.080.041.69012.10Invention Example 340.100.031.66512.50Comparative Example 350.060.001.66013.90Comparative Example 360.090.031.66012.70Comparative Example 370.090.031.65012.60Comparative Example

[0184] 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.

[0185] 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.

[0186]

[0187] 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.

Claims

1. Contains Si: 1.5 to 5.0%, Al: 0.1 to 2.0%, Mn: 0.1 to 2.0% by weight, and the remainder includes Fe and inevitable impurities. A non-oriented electrical steel sheet satisfying the following equation 1. [Formula 1] V{001} <001> / V{011} <001> ≤ 0.65 (V{001} in Equation 1 <001> Silver {001} <001> It represents the fraction of crystal grains having an orientation within 15° from V{011} <001> Silver {011} <001> ) represents the fraction of crystal grains having an orientation within 15° from the center.

2. In paragraph 1, A non-oriented electrical steel sheet satisfying the following equation 2. [Formula 2] (V{100} <001> + V{100} <031> + V{100} <110> ) / ( V{111} <112> + V{111} <011> ) ≥ 1.3 (V{100} in Equation 2 <001> Silver {100} <001> It represents the fraction of crystal grains having an orientation within 15° from V{100} <031> Silver {100} <031> It represents the fraction of crystal grains having an orientation within 15° from V{100} <110> Silver {100} <110> It represents the fraction of crystal grains having an orientation within 15° from V{111} <112> Silver {111} <112> It represents the fraction of crystal grains having an orientation within 15° from V{111} <011> Silver {111} <011> ) represents the fraction of crystal grains having an orientation within 15° from the center.

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 3. [Formula 3] B 50L - B 50D ≥ 0.08 T (B in Equation 3 50L B is the magnetic flux density measured in the rolling direction 50 , B 50D is the magnetic flux density B measured in a direction at a 45° angle to the rolling direction. 50 ) 8. In paragraph 1, A non-oriented electrical steel sheet satisfying the following equation 4. [Formula 4] B 50c - B 50D ≥ 0.03 T (B in Equation 450C B is the magnetic flux density measured in the direction perpendicular to the rolling direction. 50 , B 50D is the magnetic flux density B measured in a direction at a 45° angle to the rolling direction. 50 ) 9. In paragraph 1, A non-oriented electrical steel sheet satisfying the following equation 5. [Formula 5] (B 50L + B 50C ) / 2 ≥ 1.68 T (B in Equation 5 50L B is the magnetic flux density measured in the rolling direction 50 , B 50C is the magnetic flux density B measured in the vertical direction of the rolling 50 ) 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, The above first annealing step is a step of heating the cold rolled sheet from 40°C to the first cracking temperature (T1) at 10 to 50°C / s; A first cracking step of cracking the cold rolled sheet at a first cracking temperature (T1) of 950 to 1100°C; A second cracking step of cracking the cold rolled sheet at a second cracking temperature (T2) of 800 to 950°C; and A method for manufacturing a non-oriented electrical steel sheet, comprising a cooling step of cooling from the second cracking temperature (T2) to 670°C for 10 to 40 seconds.

11. In paragraph 10, 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%).

12. In paragraph 10, 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.

13. In paragraph 10, 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%).

14. In paragraph 10, 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%).

15. In paragraph 10, 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.

16. In paragraph 10, A method for manufacturing a non-oriented electrical steel sheet having a reduction ratio of 40 to 79% in the preliminary cold rolling step.

17. In paragraph 10, A method for manufacturing a non-oriented electrical steel sheet, wherein the cracking time of the first cracking step is 20 to 60 seconds.

18. In paragraph 10, A method for manufacturing a non-oriented electrical steel sheet, further comprising, after the first cracking step, a step of cooling to a second cracking temperature at a cooling rate of 1 to 20°C / s.

19. In paragraph 10, A method for manufacturing a non-oriented electrical steel sheet, wherein the cracking time of the second cracking step is 40 to 100 seconds.