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%, 1.5-4.5% of Si, 0.5-2.5% of Al, and 0.1-2.5% of Mn, with the remainder comprising Fe and inevitable impurities, wherein the ratio of the number of AlN particles having a particle size of 4-5 µm to the number of AlN particles having a particle size of 0.5-5 µm in a surface layer extending to a depth of 20 µm from the surface of the steel sheet is at least 0.1.

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, which improves magnetism, particularly high-frequency iron loss, by forming a large number of coarse AlN particles in a surface layer by appropriately controlling the ratio of N2 in the atmosphere during a cold-rolled sheet annealing process.

[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] A common method for improving the magnetic properties of non-oriented electrical steel is to add alloying elements such as Si, Al, and Mn. These alloying elements increase the steel's resistivity, reducing eddy current losses and lowering overall core loss. Furthermore, these alloying elements act as substitutional elements in the steel, strengthening it and increasing its strength. However, increasing the amount of Si, Al, and Mn alloying elements results in lower magnetic flux density and increased brittleness. Beyond a certain level, cold rolling becomes impossible, making commercial production impossible. In particular, thinner electrical steel sheets exhibit superior high-frequency core loss, but the resulting brittleness can be a critical issue. The maximum combined Si, Al, and Mn content for commercial production is known to be approximately 4.5 wt%. Optimizing the content of trace elements beyond this level can produce premium non-oriented electrical steel with superior magnetism and strength.

[0006] There are also reported technologies that utilize special additive elements such as REM to improve the texture and magnetic properties while reducing the core loss of non-oriented electrical steel sheets, or introduce additional manufacturing processes such as warm rolling, double rolling, and double annealing. However, all of these technologies lead to increased manufacturing costs and difficulties in mass production, so it is necessary to develop technologies that are both commercially feasible and possess excellent magnetic properties. In addition, technologies are being developed to suppress and control the formation of inclusions by minimizing the amount of impurities added and adding elements such as Ca. However, these also lead to increased manufacturing costs, and it is difficult to clearly secure their effects.

[0007] 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, which improves magnetism, particularly high-frequency iron loss, by forming a large number of coarse AlN particles in the surface layer by appropriately controlling the ratio of N2 in the atmosphere during a cold-rolled sheet annealing process.

[0008] A non-oriented electrical steel sheet according to one embodiment of the present invention contains, in wt%, 1.5 to 4.5% of Si, 0.5 to 2.5% of Al, and 0.1 to 2.5% of Mn, with the remainder being Fe and unavoidable impurities, and in a surface layer from the surface of the steel sheet to a depth of 20 μm, a ratio of the number of AlN having a grain size of 4 to 5 μm to the number of AlN having a grain size of 0.5 to 5 μm is 0.1 or more.

[0009] The density of AlN with a particle size of 0.5 to 5 ㎛ in the surface layer is 200 / cm 2 It could be as follows:

[0010] A non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following equation 1.

[0011] [Formula 1]

[0012] 0.6≤([Al]+[Mn]) / [Si]≤1

[0013] (In Equation 1, [Al], [Mn], and [Si] represent the contents (weight %) of Al, Mn, and Si, respectively.)

[0014] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include at least one of P: 0.002 to 0.02 wt%, C: 0.005 wt% or less (excluding 0%), S: 0.0005 to 0.005 wt%, Ti: 0.005 wt% or less (excluding 0%), and N: 0.005 wt% or less (excluding 0%).

[0015] 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.

[0016] 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%).

[0017] 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%).

[0018] A non-oriented electrical steel sheet according to one embodiment of the present invention may have a resistivity (ρ) of 63 μΩcm or more at 25°C.

[0019] According to one embodiment of the present invention, a non-oriented electrical steel sheet has a core loss (W 10 / 400 ) is 12.0 W / Kg or less, and the magnetic flux density (B 50 ) can be 1.60T or more.

[0020]

[0021] 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 %, 1.5 to 4.5% Si, 0.5 to 2.5% Al, and 0.1 to 2.5% Mn, with the remainder including Fe and unavoidable impurities, to manufacture a hot-rolled steel sheet; cold-rolling the hot-rolled steel sheet to manufacture a cold-rolled sheet; and annealing the cold-rolled sheet.

[0022] The cold-rolled sheet annealing step includes a soaking step and a cooling step, and the ratio of the volume fraction of N2 in the atmospheric gas in the cooling step to the volume fraction of N2 in the atmospheric gas in the soaking step is 0.99 or less.

[0023] Slavs can satisfy the following equation 1.

[0024] [Formula 1]

[0025] 0.6≤([Al]+[Mn]) / [Si]≤1

[0026] (In Equation 1, [Al], [Mn], and [Si] represent the contents (weight %) of Al, Mn, and Si, respectively.)

[0027] The slab may further include at least one of P: 0.002 to 0.02 wt%, C: 0.005 wt% or less (excluding 0%), S: 0.0005 to 0.005% wt%, Ti: 0.005 wt% or less (excluding 0%), and N: 0.005 wt% or less (excluding 0%).

[0028] 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.

[0029] 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%).

[0030] 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%), and Mg: 0.0050 wt% or less (excluding 0%).

[0031] In the cracking step, the cracking temperature may be 800 to 1100°C, and the cooling step may be a step of cooling from the cracking temperature to 750°C.

[0032] The volume fraction of N2 in the atmosphere during the cracking and cooling stages may be less than 85%, respectively.

[0033] The volume fraction of N2 in the atmosphere at the cracking stage can satisfy the following equation 2.

[0034] [Formula 2]

[0035] 0.03 ≤ ([N]×[N2]) / [Al] ≤ 0.17

[0036] (In Equation 2, [N] and [Al] represent the contents (weight%) of N and Al in the steel plate, and [N2] represents the volume fraction (volume%) of N2 in the atmosphere at the cracking stage.)

[0037] A non-oriented electrical steel sheet according to one embodiment of the present invention has excellent magnetic flux density and high-frequency iron loss at the same time.

[0038] Ultimately, the non-oriented electrical steel sheet according to one embodiment of the present invention contributes to the manufacture of eco-friendly automobile motors, high-efficiency home appliance motors, and super-premium motor cores.

[0039] Figure 1 is a drawing schematically showing a cross-section of a non-oriented electrical steel sheet according to one embodiment of the present invention.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Also, unless otherwise stated, % means weight%, and 1 ppm is 0.0001 weight%.

[0044] 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.

[0045] 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.

[0046] 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.

[0047]

[0048] A non-oriented electrical steel sheet according to one embodiment of the present invention includes, in wt%, Si: 1.5 to 4.5%, Al: 0.5 to 2.5%, and Mn: 0.1 to 2.5%, with the remainder being Fe and unavoidable impurities.

[0049] Below, the reasons for the limitation of the components of non-oriented electrical steel sheets are explained.

[0050]

[0051] Si: 1.50 to 4.50 wt%

[0052] 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 1.50 to 4.50 wt%. More specifically, it may be included in an amount of 2.00 to 4.30 wt%. More specifically, it may be included in an amount of 2.50 to 4.10 wt%.

[0053]

[0054] Al: 0.50 to 2.50 wt%

[0055] Aluminum (Al) acts as an element that increases the resistivity of the material, thereby lowering iron loss and reducing magnetic anisotropy, thereby reducing magnetic deviation in the rolling direction and the direction perpendicular to the rolling direction. If too little Al is added, fine nitrides may be formed, making it difficult to achieve the effect of improving magnetism. If too much Al is added, excessive nitrides may be formed, which deteriorates magnetism and causes problems in all processes such as steelmaking and continuous casting, which can significantly reduce productivity. Therefore, Al may be included in an amount of 0.50 to 2.50 wt%. More specifically, it may be included in an amount of 0.70 to 2.30 wt%. More specifically, it may be included in an amount of 1.30 to 2.00 wt%.

[0056]

[0057] Mn: 0.10 to 2.50 wt%

[0058] 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 0.10 to 2.50 wt%. More specifically, it may be included in an amount of 0.30 to 2.00 wt%. More specifically, it may be included in an amount of 0.50 to 1.80 wt%.

[0059] A non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following equation 1.

[0060] [Formula 1]

[0061] 0.60 ≤([Al]+[Mn]) / [Si]≤ 1.00

[0062] (In Equation 1, [Al], [Mn], and [Si] represent the contents (weight %) of Al, Mn, and Si, respectively.)

[0063] The core loss of non-oriented electrical steel is divided into hysteresis loss and eddy current loss. Eddy current loss can be significantly reduced by increasing the resistivity of the steel by adding elements such as Si, Al, and Mn. In particular, as the frequency increases, the proportion of eddy current loss in the total core loss increases. Therefore, it is necessary to control the resistivity of the steel above a certain level to ensure excellent high-frequency core loss. It was confirmed that the higher the resistivity, the better the characteristics can be secured. Among Si, Al, and Mn, Si is the element that increases the resistivity of the steel the most, but increasing the Si content increases the brittleness of the steel, which reduces productivity. Therefore, to increase the resistivity of the steel while ensuring productivity, an appropriate amount of Al and Mn must be added along with Si. The results of a review of the appropriate addition ratio showed that when it is controlled to satisfy Equation 1, excellent magnetic properties can be achieved while ensuring productivity. More specifically, the value of Equation 1 can be 0.70 to 0.95.

[0064]

[0065] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include at least one of P: 0.002 to 0.02 wt%, C: 0.005 wt% or less (excluding 0%), S: 0.0005 to 0.005 wt%, Ti: 0.005 wt% or less (excluding 0%), and N: 0.005 wt% or less (excluding 0%).

[0066] P: 0.002 to 0.02 wt%

[0067] Phosphorus (P) is a grain boundary segregation element that can improve magnetic flux density. If the amount added is too small, the effect is insufficient. If added in excess, it can inhibit grain growth, resulting in poor iron loss. Furthermore, grain boundary segregation can impair rollability, thereby reducing productivity. More specifically, P may be included in an amount of 0.003 to 0.015 wt%.

[0068] C: 0.005 wt% or less

[0069] 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%.

[0070] S: 0.0005 to 0.005 wt%

[0071] Sulfur (S) is an element that forms sulfides such as MnS, CuS, and (Cu,Mn)S, which are detrimental to magnetic properties, so it is advantageous to add it in as low a amount as possible. However, if it is included in too little, it is rather detrimental to the formation of texture, and the formation of fine sulfides is promoted, which may lower magnetism and increase the cost of steelmaking. On the other hand, if it is included in too much, the increase in sulfides may worsen magnetic properties and worsen hot workability. More specifically, S may be included in an amount of 0.0010 to 0.0045 wt%.

[0072] Ti: 0.005 wt% or less

[0073] Titanium (Ti) can be limited because it forms carbonitrides and thus hinders domain movement. More specifically, Ti can be included in an amount of 0.0001 to 0.005 wt%. More specifically, Ti can be included in an amount of 0.0001 to 0.003 wt%.

[0074] N: 0.005 wt% or less

[0075] 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%.

[0076]

[0077] 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.

[0078] Sn and Sb

[0079] Tin (Sn) and antimony (Sb) play a role in suppressing the development of {111} orientation, which segregates at the grain boundary in the early stage of final recrystallization annealing and worsens magnetism. If too much Sn and Sb are added, the recovery and growth of coarse stretched band structure may be hindered and the surface quality may be deteriorated. Therefore, at least one of Sn and Sb may be further added within the above-mentioned range. More specifically, Sn may be included in an amount of 0.005 to 0.200 wt% or Sb may be included in an amount of 0.005 to 0.200 wt%.

[0080] Bi, Pb, Ge, and As

[0081] 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.

[0082]

[0083] 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%).

[0084] Cu: 0.005 to 0.200 wt%

[0085] 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%.

[0086] Cr: 0.01 to 0.50 wt%

[0087] 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%.

[0088] Ni: 0.05 wt% or less

[0089] 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.

[0090] Zn: 0.01 wt% or less

[0091] 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%.

[0092] Co: 0.05 wt% or less

[0093] 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.

[0094]

[0095] 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%).

[0096] Mo: 0.030 wt% or less

[0097] 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%.

[0098] B: 0.0050 wt% or less

[0099] 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%.

[0100] V: 0.0050 wt% or less

[0101] 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%.

[0102] Ca: 0.0050 wt% or less

[0103] 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.

[0104] Nb: 0.0050 wt% or less

[0105] 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%.

[0106] Zr: 0.0050 wt% or less

[0107] 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%.

[0108] Te: 0.0100 wt% or less

[0109] 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%.

[0110] Mg: 0.0050 wt% or less

[0111] 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%.

[0112]

[0113] 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).

[0114]

[0115] Fig. 1 schematically illustrates a cross-section of a non-oriented electrical steel sheet according to one embodiment of the present invention. As shown in Fig. 1, the non-oriented electrical steel sheet (100) according to one embodiment of the present invention includes a surface layer (20) extending from the surface of the steel sheet to a depth of 20 μm.

[0116] As described above, in one embodiment of the present invention, by appropriately controlling the characteristics of AlN present in the surface layer (20), high-frequency iron loss can be improved.

[0117] In the surface layer (10) from the surface of the steel plate to a depth of 20 ㎛, the ratio of the number of AlN particles having a particle size of 4 to 5 ㎛ to the number of AlN particles having a particle size of 0.5 to 5 ㎛ is 0.1 or more.

[0118] AlN refers to the agglomeration of Al and N components in the steel sheet into particles. In other words, it refers to a portion containing aluminum and nitrogen in larger amounts than the base material content of the steel sheet. In one embodiment of the present invention, AlN can be observed and analyzed for components using SEM, TEM, etc., and the components and size can be measured for a large area using Auto-SEM, etc. The cross-section for measuring AlN is not particularly limited, but may be a normal plane (TD plane) in the rolling vertical direction (TD direction) of the steel sheet. In the cross-section, when both the upper surface layer and the lower surface layer are included, the characteristics can be satisfied for both the upper surface and the lower surface layers. The particle size of AlN refers to the diameter of an imaginary circle having the same area as the area occupied by AlN.

[0119] The reason why AlN in the surface layer (10) is specified in one embodiment of the present invention is that the influence of AlN in the surface layer (10) on magnetism is particularly large.

[0120] In addition, even if AlN exists, the presence of a large number of coarse AlN with a particle size of 4 to 5 μm can suppress the formation of fine AlN and prevent magnetization interference by fine AlN, which is advantageous for high-frequency iron loss. More specifically, the ratio of the number of AlN with a particle size of 4 to 5 μm to the number of AlN with a particle size of 0.5 to 5 μm is 0.1 to 0.25. More specifically, it is 0.11 to 0.20. The AlN ratio can be analyzed using an image analysis program using images obtained through TEM or SEM and EDS. In order to reduce the deviation according to the measurement position, the ratio can be obtained by measuring non-overlapping positions twice or more for a specimen with an area of ​​5 mm × 5 mm or more, and using the average value.

[0121] In one embodiment of the present invention, the density of AlN having a particle size of 0.5 to 5 ㎛ is 200 / cm 2It can be below. If the density of AlN is high, even if the aforementioned AlN ratio is high, the absolute number of fine AlN particles increases, which can have a negative effect on iron loss. More specifically, the density of AlN is 50 to 200 particles / cm. 2 It can be. More specifically, 100 to 195 / cm 2 It can be. The density of AlN can be obtained in the same way as the ratio of AlN mentioned above.

[0122] The size ratio and density of AlN can be controlled by controlling the composition of steel and the atmosphere during cold-rolled sheet annealing, and the specific details are explained in relation to the manufacturing method of non-oriented electrical steel sheet.

[0123] According to one embodiment of the present invention, a non-oriented electrical steel sheet may have a resistivity (ρ) of 63 μΩcm or more at 25°C. The higher the resistivity, the more the high-frequency iron loss may be improved. More specifically, the resistivity (ρ) may be 65 to 85 μΩcm at 25°C.

[0124]

[0125] In one embodiment of the present invention, the magnetic flux density in the rolling direction is excellent and the high-frequency iron loss is excellent. Specifically, the non-oriented electrical steel sheet according to one embodiment of the present invention has an iron loss (W 10 / 400 ) is 12.0 W / Kg or less, and the magnetic flux density (B 50 ) can be 1.60T or more.

[0126] B 50 refers to the magnetic flux density induced in a magnetic field of 5000 A / m.

[0127] W 10 / 400 is the iron loss when a magnetic flux density of 1.0 T is induced at a frequency of 400 Hz.

[0128] In one embodiment of the present invention, B 50 and W 10 / 400The values ​​measured in the rolling direction (RD direction) and the rolling vertical direction (TD direction) are averaged and shown. More specifically, the non-oriented electrical steel sheet according to one embodiment of the present invention has a core loss (W 10 / 400 ) is 8.0 to 10.5 W / Kg, and the magnetic flux density (B 50 ) may be 1.61T to 1.65T.

[0129]

[0130] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention includes a step of hot-rolling a slab to manufacture a hot-rolled steel sheet; a step of cold-rolling the hot-rolled steel sheet to manufacture a cold-rolled steel sheet; and a cold-rolled steel sheet annealing step of annealing the cold-rolled steel sheet.

[0131] Below, each step is explained in detail.

[0132] First, the slab is hot rolled.

[0133] 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.

[0134] Specifically, the slab contains Si: 1.5 to 4.5%, Al: 0.5 to 2.5%, and Mn: 0.1 to 2.5% by weight, with the remainder being Fe and unavoidable impurities.

[0135] As other additional elements have been described in the alloy composition of non-oriented electrical steel sheets, redundant descriptions are omitted.

[0136] 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.

[0137] Next, the slab is hot-rolled to produce a hot-rolled sheet. The hot-rolled sheet may have a thickness of 1.0 to 4.5 mm. In one embodiment of the present invention, a preliminary cold-rolling step may be additionally included before cold rolling, so that even if the hot-rolled sheet is relatively thick, a non-oriented electrical steel sheet of an appropriate thickness can be produced. More specifically, the thickness of the hot-rolled sheet may be 1.5 to 3.5 mm.

[0138] The step of manufacturing the hot rolled sheet may include a step of finish rolling at a temperature of 850°C or higher.

[0139] If the hot rolling finishing temperature is too low, the rolling load increases, which reduces the hot rolling workability. In addition, a lot of deformation structures remain in the hot rolled steel sheet, which can cause an increase in the rolling load during the subsequent preliminary cold rolling process. In addition, during the intermediate annealing, deformation structures are removed. <111> / ND The recrystallization of the orientation grains is promoted, resulting in a lower magnetic flux density. Therefore, the higher the hot rolling finishing temperature, the better, and more specifically, finishing rolling at a temperature of 860 to 1000°C is preferable.

[0140] The step of manufacturing a hot-rolled sheet may include a step of performing water cooling after a time of 0.1 seconds or more after finish rolling.

[0141] After the finishing rolling, cooling is performed for coiling. When water cooling is performed immediately after the finishing rolling (i.e., within less than 0.1 seconds), the steel sheet may be rapidly cooled, causing deformation and residual stress, making coiling difficult. In addition, in terms of microstructure, the deformation stress after the finishing rolling is not released and remains, causing an increase in the rolling load and micro-stress in the subsequent cold rolling stage. <111> / ND may cause recrystallization of the orientation. Therefore, it is necessary to maintain the hot-rolled deformation structure for more than 0.1 seconds immediately after the hot-rolled finishing rolling to allow recovery and recrystallization, thereby reducing the rolling load during the subsequent preliminary cold rolling. <111> / ND suppresses the formation of azimuth recrystallization grains. More specifically, water cooling can be performed after 0.3 to 5.0 seconds, and even more specifically, water cooling can be performed after 0.5 to 3.0 seconds.

[0142] The step of manufacturing a hot rolled sheet may include a coiling step at a temperature of 600 to 800°C. A rough rolling step may also be included before the finish rolling step.

[0143] If the temperature during the coiling stage is controlled too low, the recovery and recrystallization of the hot-rolled deformation structure will not occur well, and the cooling load will increase in order to quickly cool the steel sheet to a low temperature, which may make it difficult to coil the supercooled coil. On the other hand, if the temperature is too high, recovery and recrystallization may be promoted, but additional oxidation by atmospheric oxygen may occur during coiling, which may cause thicker scale formation and the problem of intergranular oxidation. Intergranular oxidation of hot-rolled sheets promotes intergranular corrosion during the subsequent pickling process, which increases the possibility of surface stripe defects and may cause severe wear of the rolling rolls. Therefore, it is recommended that the coiling temperature be 600 to 800℃, and more specifically, coiling can be performed at 600 to 750℃.

[0144] After manufacturing hot-rolled steel sheets, hot-rolled sheet annealing can be performed before cold rolling. The soaking temperature during hot-rolled sheet annealing can be 800 to 1200℃. If the annealing temperature is too low, the recrystallized structure may not be formed or may grow finely, which will have little effect on increasing the magnetic flux density. If the annealing temperature is too high, the magnetic properties may actually deteriorate, and the rolling workability may deteriorate due to deformation of the plate shape. More specifically, the temperature range can be 830 to 1170℃. The soaking time can be 15 to 180 seconds. Hot-rolled sheet annealing can also be omitted if necessary.

[0145] Returning to the description of the manufacturing method of non-oriented electrical steel sheet, cold-rolled steel sheet is cold-rolled to produce cold-rolled steel sheet. At this time, cold rolling can be performed at a reduction ratio of 30 to 80%. 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 can cause problems in improving the magnetic flux density and iron loss. On the other hand, if the reduction ratio is too high, it can cause problems in the subsequent annealing process. <111> / ND The recrystallization of the orientation grains is promoted and the grains become finer, which may cause problems such as poor magnetic flux density and increased iron loss. More specifically, the reduction ratio can be 40 to 70%. The thickness can be 0.1 mm to 0.5 mm. More specifically, it can be 0.15 to 0.35 mm. The cold rolling step can use 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 using 12 or more rolling rolls.

[0146] Next, the cold-rolled sheet is annealed. In one embodiment of the present invention, the nitrogen fraction in the atmosphere is controlled during the annealing of the cold-rolled sheet to appropriately form AlN in the surface layer (10).

[0147] The cold rolled sheet annealing step includes a soaking step and a cooling step. The soaking step is a heat treatment step at a soaking temperature of 800 to 1100℃. If the soaking temperature is too low, <111> / ND The recrystallization of the orientation grains is promoted, and the grains become finer, making it difficult to secure excellent magnetic flux density characteristics. If the soaking temperature is too high, the grains grow coarsely, increasing iron loss. In addition, an oxide layer or nitride layer may form on the surface of the steel sheet from the annealing atmosphere gas, which may also increase iron loss. More specifically, the soaking temperature may be 850 to 1050°C. The soaking time may be 10 to 300 seconds.

[0148] The cooling step may be a step of cooling from the soaking temperature to 750°C. The cooling rate in the cooling step may be 1 to 30°C / s. If the cooling rate is too fast, the magnetism may be degraded due to stress caused by thermal shock. If the cooling rate is too slow, the crystal grains may coarsen, degrading the magnetism. More specifically, the cooling rate may be 3 to 20°C / s.

[0149] The ratio of the volume fraction of N2 in the atmospheric gas in the cooling stage to the volume fraction of N2 in the atmospheric gas in the cracking stage may be 0.99 or less. If the volume fraction of N2 in the cooling stage is relatively higher than that in the cracking stage, a nitride surface layer may be formed during cooling, which may result in poor magnetism. More specifically, the ratio of the volume fraction of N2 in the atmospheric gas in the cooling stage to the volume fraction of N2 in the atmospheric gas in the cracking stage may be 0.75 to 0.99.

[0150] In one embodiment of the present invention, by independently distinguishing the gas input into the cracking zone and cooling zone sections, the atmosphere in the cracking stage and the cooling stage can be independently controlled.

[0151] The volume fraction of N2 in the atmosphere during the soaking and cooling stages may be 85% or less. If the volume fraction of N2 in each stage is too high, a large number of nitrides may be generated, resulting in poor magnetic properties. More specifically, the volume fraction of N2 in the atmosphere during the soaking and cooling stages may be 65 to 84%, respectively.

[0152] The volume fraction of N2 in the atmosphere at the cracking stage can satisfy the following equation 2.

[0153] [Formula 2]

[0154] 0.03 ≤ ([N]×[N2]) / [Al] ≤ 0.17

[0155] When equation 2 is satisfied, AlN can be formed coarsely in the surface layer (10). More specifically, the value of equation 2 can be 0.030 to 0.165.

[0156] After the cold-rolled sheet annealing step, a step of forming an insulating film may be further included to ensure insulation and corrosion resistance on the steel sheet. Since the insulating film is widely known, a detailed description thereof will be omitted. When the insulating film is formed, the surface layer (10) refers to the portion extending up to 2 μm from the boundary between the insulating film and the steel sheet substrate into the steel sheet.

[0157]

[0158] 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.

[0159]

[0160] Example 1

[0161] Slabs were manufactured with the composition shown in Table 1 below. The remainder was Fe. The slabs were heated to 1180°C, hot-rolled to a thickness of 2.2 mm, and then coiled. The hot-rolled steel sheets, coiled and cooled in air, were hot-rolled at 1000°C, pickled, cold-rolled to a thickness of 0.2 mm, and finally cold-rolled. At this time, the soaking temperature and atmospheric conditions were varied as shown in Table 2 below to manufacture the sheets.

[0162] For each specimen, the resistivity at room temperature was measured using the 4-point probe method, and after polishing the surface in the direction of the specimen thickness, the distribution of AlN was observed and analyzed by measuring it more than twice using Auto-SEM in an area of ​​5 mm × 5 mm or more. After processing the magnetic measurement specimen, the iron loss W 10 / 400 and magnetic flux density B 50 The results were measured and shown in Table 3 below.

[0163] The magnetic properties were measured using an Epstein tester by preparing Epstein specimens at each angle, and the average results in the rolling direction and the direction perpendicular to the rolling are summarized in Table 3 below.

[0164] Steel grade CSiMnPSAlTiN10.00112.960.800.0100.00191.690.00360.002220.00224.041.110.0020.00261.460.00150.001030.00413.511.500.0020.0017 1.410.00120.002940.00113.400.800.0060.00381.750.00200.002950.00372.961.120.0050.00411.060.00100.001760.00183.010.440.0110.001 22.000.00160.001470.00433.321.260.0050.00421.580.00210.002180.00053.400.610.0050.00241.670.00050.001890.00283.901.310.0030.00 362.390.00080.0036100.00252.910.620.0070.00061.370.00300.0031110.00143.281.300.0140.00280.720.00360.0006120.00382.850.510.014 0.00441.380.00220.0027130.00393.840.650.0080.00301.970.00310.0011140.00363.621.550.0090.00081.270.00070.0005150.00412.951.12 0.0110.00161.690.00250.0011160.00153.710.790.0060.00192.130.00280.0008170.00373.041.350.0100.00121.870.00260.0036180.00134.08 1.270.0040.00170.570.00340.0041190.00073.200.290.0120.00101.040.00160.0012200.00342.820.430.0120.00161.230.00220.0018210.0027 2.560.890.0100.00411.040.00140.0029220.00283.391.160.0110.00231.220.00100.0042230.00143.331.360.0040.00420.990.00320.0033240.0023.441.550.0040.00191.200.00220.0020250.00444.010.340.0100.00191.490.00240.0025260.00133.611.870.0030.00261.760.00210.0045270.00163.310.590.0100.00441.320.00080.0040280.00173.681.550.0080.00280.800.00060.0021290.00143.071.960.0090.00290.780.00300.0034300.00063.250.470.0040.00141.690.00150.0017.

[0165] Steel grade (Al+Mn) / Si resistivity (μΩcm) Cold rolled sheet annealing cracking temperature (℃) Cracking stage N2gas (v%) Cooling stage N2gas (v%) Formula 2 value Cooling stage / cracking Step N2 ratio 10.8470.387074.469.80.0970.9420.6481.7109083.065.80.0570.7930.8377.3101074.869.80.1540.9340.7576.092074.173.70.1230.9950.7465.0101084.076.70.1350.9160.8172.3103076.968.10.0540.8970.8675.798076.872.30.1020.9480.6774.08808 2.576.60.0890.9390.9591.785074.365.20.1120.88100.6865.195071.269.00.1610.97110.6265.8103076.272.30.0640.95120.6663.997078.776.40.1540.97130.6882.687082.366.00.0460.8140.7877.395083.980.70.0330.96150.9572.0103071.369.10.0460.97 160.7983.791079.878.50.0300.98171.0676.490079.982.80.1541.04180.4573.0102085.468.50.6140.8190.4262.8109076.479.20.0881.04200.5961.494070.569.10.1030.98210.7559.098076.578.50.2131.03220.7071.990085.675.80.2950.89230.7169.810508 6.988.30.2901.02240.8074.492072.685.90.1211.18250.4677.391071.575.30.1201.05261.0184.5104082.380.30.2100.98270.5868.996071.575.00.2171.05280.6472.690078.076.30.2050.98290.8967.890075.579.00.3291.05300.6671.796071.679.60.0721.11

[0166] Steel grade 0.5 to 5 ㎛ AlN density (units / cm) 2 )4 to 5㎛AlN / 0.5 to 5㎛AlNW10 / 400(W / Kg)B50(T)Remarks11300.1210.01.64Invention Example21800.138.91.62Invention Example31030.249.31.62Invention Example41550.139.51.63Invention Example51250.1510.41.64Invention Example61670.1510.11.62Invention Example71020.199.31.6 4 inventions 81200.159.41.63 inventions 91100.159.61.62 inventions 101550.159.91.62 inventions 111220.169.61.62 inventions 121220.1210.31.63 inventions 131650.139.61.63 inventions 141770.128.61.62 inventions 151000.2010.11.6 4 Invention Example 161390.148.81.62 Invention Example 172350.0612.31.58 Comparative Example 182220.1212.11.57 Comparative Example 192030.0813.41.57 Comparative Example 201360.1412.51.59 Comparative Example 211910.0913.01.59 Comparative Example 222270.0812.31.57 Comparative Example 232180.0 913.21.57Comparative Example 242200.1112.71.57Comparative Example 251920.0712.21.57Comparative Example 262130.0813.11.57Comparative Example 271800.0912.51.59Comparative Example 282490.0912.51.59Comparative Example 292150.1113.01.58Comparative Example 302280.0912.61.58Comparative Example

[0167] As shown in Tables 1 to 3, it can be confirmed that the examples in which the steel components are appropriately controlled and the process conditions are appropriately controlled so that AlN is appropriately formed on the surface layer have excellent iron loss and magnetic flux density.

[0168] On the other hand, steel No. 17 did not satisfy Equation 1, although the amount of each component added satisfied the management range, and the density of AlN was high due to the high N2 ratio in the cooling stage, and the coarse AlN ratio was low, resulting in high iron loss W. 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0169] Steel No. 18 did not satisfy Equation 1, and the density of AlN was high due to the high N2 ratio in the cooling stage, and the iron loss W 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0170] Steel No. 19 did not satisfy the control range for the amount of each component added, but did not satisfy the value of Equation 1 and the resistivity (ρ) at room temperature. In addition, the N2 ratio was high during the cooling stage, so the density of AlN was high, and the coarse AlN ratio was low, resulting in a high iron loss W. 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0171] Steel No. 20 does not satisfy the conditions of Equation 1 and the resistivity (ρ) at room temperature, resulting in a core loss W 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0172] Steel No. 21 did not satisfy the resistivity (ρ) condition at room temperature, had a high N2 ratio in the cooling stage, and did not satisfy Equation 2, so the coarse AlN ratio was low, resulting in a high iron loss W. 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0173] Steel No. 22 has a high N2 ratio at the crack stage, does not satisfy Equation 2, has a high AlN density, and has a low coarse AlN ratio, resulting in a high iron loss W. 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0174] Steel No. 23 has a high N2 ratio in the cracking and cooling stages, does not satisfy Equation 2, has a high AlN density, and has a low coarse AlN ratio, resulting in a high iron loss W. 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0175] Steel No. 24 has a high N2 ratio in the cooling stage, so the density of AlN is high and the iron loss W 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0176] Steel No. 25 does not satisfy Equation 1, has a high N2 ratio in the cooling stage, a low coarse AlN ratio, and high iron loss W. 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0177] Steel No. 26 does not satisfy Equation 1 and Equation 2, so the density of AlN is high and the coarse AlN ratio is low, resulting in a high iron loss W. 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0178] Steel No. 27 does not satisfy Equation 1, does not satisfy Equation 2, has a high N2 ratio in the cooling stage, has a low coarse AlN ratio, and has a high iron loss W. 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0179] Steel No. 28 does not satisfy Equation 2, so the density of AlN is high and the coarse AlN ratio is low, resulting in a high iron loss W. 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0180] Steel No. 29 does not satisfy the value of Equation 2, has a high N2 ratio in the cooling stage, and has a high density of AlN and a high iron loss W. 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0181] Steel No. 30 has a high N2 ratio in the cooling stage, so the density of AlN is high, and the coarse AlN ratio is low, resulting in iron loss W. 10 / 400 and magnetic flux density B 50 This appeared to be inferior.

[0182]

[0183] 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.

[0184] [Explanation of symbols]

[0185] 100: Electrical steel plate 10: Surface layer

Claims

Containing Si: 1.5 to 4.5% by weight, Al: 0.5 to 2.5%, and Mn: 0.1 to 2.5%, with the remainder being Fe and inevitable impurities; A non-oriented electrical steel sheet having a ratio of the number of AlN having a grain size of 4 to 5 ㎛ to the number of AlN having a grain size of 0.5 to 5 ㎛ of 0.1 or more in a surface layer from the surface of the steel sheet to a depth of 20 ㎛. In the first paragraph, The density of AlN having a particle size of 0.5 to 5 ㎛ in the above surface layer is 200 / cm 2 Below is the non-oriented electrical steel sheet. In the first paragraph, A non-oriented electrical steel sheet satisfying the following equation 1. [Formula 1] 0.6≤([Al]+[Mn]) / [Si]≤1 (In Equation 1, [Al], [Mn], and [Si] represent the contents (weight%) of Al, Mn, and Si, respectively.) In the first paragraph, A non-oriented electrical steel sheet further comprising at least one of P: 0.002 to 0.02 wt%, C: 0.005 wt% or less (excluding 0%), S: 0.0005 to 0.005 wt%, Ti: 0.005 wt% or less (excluding 0%), and N: 0.005 wt% or less (excluding 0%). In the first paragraph, 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. In the first paragraph, 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%). In the first paragraph, 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%). In the first paragraph, Non-oriented electrical steel sheet having a resistivity (ρ) of 63 μΩcm or more at 25℃. In the first paragraph, Iron Hand(W 10 / 400 ) is 12.0 W / Kg or less, and the magnetic flux density (B 50 ) Non-oriented electrical steel sheet with a strength of 1.60T or higher. A step of manufacturing a hot-rolled steel sheet by hot-rolling a slab containing Si: 1.5 to 4.5% by weight, Al: 0.5 to 2.5%, and Mn: 0.1 to 2.5% by weight, with the remainder being Fe and unavoidable impurities; A step of manufacturing a cold rolled sheet by cold rolling the hot rolled steel sheet above, and A cold rolled sheet annealing step for annealing the above cold rolled sheet; Including, The above cold rolled sheet annealing step includes a soaking step and a cooling step, A method for manufacturing a non-oriented electrical steel sheet, wherein the ratio of the volume fraction of N2 in the atmospheric gas in the cooling step to the volume fraction of N2 in the atmospheric gas in the cracking step is 0.99 or less. In Article 10, The above slab is a method for manufacturing a non-oriented electrical steel sheet satisfying the following equation 1. [Formula 1] 0.6≤([Al]+[Mn]) / [Si]≤1 (In Equation 1, [Al], [Mn], and [Si] represent the contents (weight%) of Al, Mn, and Si, respectively.) In Article 10, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further includes at least one of P: 0.002 to 0.02 wt%, C: 0.005 wt% or less (excluding 0%), S: 0.0005 to 0.005 wt%, Ti: 0.005 wt% or less (excluding 0%), and N: 0.005 wt% or less (excluding 0%). In Article 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. In Article 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%). In Article 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%). In Article 10, A method for manufacturing a non-oriented electrical steel sheet, wherein the cracking temperature in the above cracking step is 800 to 1100°C, and the cooling step is a step of cooling from the above cracking temperature to 750°C. In Article 10, A method for manufacturing a non-oriented electrical steel sheet, wherein the volume fraction of N2 in the atmosphere in the above-mentioned cracking step and the above-mentioned cooling step is each 85% or less. In Article 10, A method for manufacturing a non-oriented electrical steel sheet, wherein the volume fraction of N2 in the atmosphere at the above cracking stage satisfies the following equation 2. [Formula 2] 0.03 ≤ ([N]×[N2]) / [Al] ≤ 0.17 (In Equation 2, [N] and [Al] represent the contents (in weight%) of N and Al in the steel plate, and [N2] represents the volume fraction (in volume%) of N2 in the atmosphere at the cracking stage.)

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