Hot-rolled steel sheet for non-oriented electrical steel sheet, method for manufacturing same, and method for manufacturing non-oriented electrical steel sheet

Abstract

A hot-rolled steel sheet for a non-oriented electrical steel sheet according to an embodiment of the present invention contains, in wt%, 2.5-4.5% of Si, 0.1-2.5% of Mn, and 1.0-2.5% of Al, with the remainder comprising Fe and inevitable impurities, wherein the peak of a heat flow curve measured using differential scanning calorimetry (DSC) while heating is in the range of 325°C to 475°C.

Description

Hot rolled steel sheet for non-oriented electrical steel sheet, manufacturing method thereof, and manufacturing method of non-oriented electrical steel sheet

[0001] One embodiment of the present invention relates to a hot-rolled steel sheet for non-oriented electrical steel, a method for manufacturing the same, and a method for manufacturing the non-oriented electrical steel sheet. Specifically, one embodiment of the present invention relates to a hot-rolled steel sheet for non-oriented electrical steel, a method for manufacturing the same, and a method for manufacturing the non-oriented electrical steel sheet, wherein the regular fraction within the hot-rolled steel sheet is suppressed by appropriately controlling the cooling rate after hot rolling.

[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] The most basic and effective way to reduce the iron loss, which is one of the important characteristics of non-oriented electrical steel sheets, is to increase the addition amount of elements with high resistivity, such as Si, Al, and Mn, or to make the steel sheet thinner. Increasing the addition amount of Si, Al, and Mn increases the resistivity of the steel, which reduces the eddy current loss among the iron loss of the non-oriented electrical steel sheet, thereby reducing the iron loss. In the case of high-frequency iron loss, the proportion of eddy current loss is larger, so it can be a very effective method for reducing high-frequency iron loss. However, the effect varies depending on the addition ratio, and since the magnetic flux density deteriorates as the addition amount of alloying elements increases, the appropriate addition amount and the addition ratio between the Si, Al, and Mn additions must be properly controlled in order to secure excellent iron loss and magnetic flux density.

[0006] Meanwhile, as the content of Si, Al, and Mn increases, problems with the magnetic flux density of the material may arise due to the regular formation of B2 and DO3 in areas where the above elements are locally concentrated. The exact principle has not yet been elucidated, but it is known that when regular phases exist in hot-rolled steel sheets, which are the raw materials for electrical steel sheets, it is difficult to secure magnetic flux density in the final non-oriented electrical steel sheets.

[0007] Ultimately, when manufacturing electrical steel sheets with increased Si, Al, and Mn contents to reduce iron loss, it is necessary to secure hot-rolled steel sheets with controlled B2 and DO3 regularity formation in local areas.

[0008] One embodiment of the present invention provides a hot-rolled steel sheet for non-oriented electrical steel, a method for manufacturing the same, and a method for manufacturing the non-oriented electrical steel sheet. Specifically, one embodiment of the present invention provides a hot-rolled steel sheet for non-oriented electrical steel, a method for manufacturing the same, and a method for manufacturing the non-oriented electrical steel sheet, wherein the regular fraction within the hot-rolled steel sheet is suppressed by appropriately controlling the cooling rate after hot rolling.

[0009] A hot-rolled steel sheet for non-oriented electrical steel according to one embodiment of the present invention contains, in wt%, Si: 2.5 to 4.5%, Mn: 0.1 to 2.5%, Al: 1.0 to 2.5%, the remainder Fe, and other inevitable impurities, and a peak of a heat flow curve measured during a heating process by differential scanning calorimetry (DSC) exists at 325 to 475°C.

[0010] A hot-rolled steel sheet for non-oriented electrical steel 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 hot-rolled steel sheet for non-oriented electrical steel 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 hot-rolled steel sheet for non-oriented electrical steel 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 hot-rolled steel sheet for non-oriented electrical steel 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 hot-rolled steel sheet for non-oriented electrical steel 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 hot-rolled steel sheet for non-oriented electrical steel according to one embodiment of the present invention may have a resistivity (ρ) of 63 μΩcm or more at 25°C.

[0019]

[0020] A method for manufacturing a hot-rolled steel sheet for non-oriented electrical steel according to one embodiment of the present invention comprises the steps of: hot-rolling a slab containing, by weight %, Si: 2.5 to 4.5%, Mn: 0.1 to 2.5%, Al: 1.0 to 2.5%, the remainder Fe, and other unavoidable impurities to manufacture a hot-rolled steel sheet; and the step of cooling the hot-rolled steel sheet.

[0021] The cooling step can cool at a temperature range of 400 to 100°C at a rate of 30°C / second or more.

[0022] After the step of cooling the hot-rolled steel sheet, a step of coiling the hot-rolled steel sheet is included, and the step of coiling the hot-rolled steel sheet can be coiled at a temperature of 100°C or less.

[0023] The cooling step can cool in a temperature range of 400 to 100°C at a rate of 30°C / sec to 100°C / sec.

[0024] 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%).

[0025] 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.

[0026] 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%), Zn: 0.01 wt% or less (excluding 0%), and Co: 0.05% or less (excluding 0%).

[0027] 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%).

[0028]

[0029] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention comprises the steps of preparing a hot-rolled steel sheet containing, by weight %, 2.5 to 4.5% of Si, 0.1 to 2.5% of Mn, 1.0 to 2.5% of Al, the remainder being Fe and other unavoidable impurities, and having a peak in a heat flow curve measured during a heating process using a differential scanning calorimeter (DSC) at 325 to 475°C; cold-rolling the hot-rolled steel sheet to manufacture a cold-rolled steel sheet; and annealing the cold-rolled steel sheet.

[0030] The manufactured 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.

[0031] A hot-rolled steel sheet for non-oriented electrical steel according to one embodiment of the present invention has regular generation suppressed, and a non-oriented electrical steel sheet manufactured using the same has excellent magnetic flux density and high-frequency iron loss at the same time.

[0032] 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.

[0033] Figure 1 is a differential scanning calorimetry (DSC) analysis graph of the steel plate manufactured in Invention Example 1.

[0034] Figure 2 is a differential scanning calorimetry (DSC) analysis graph of the steel plate manufactured in Invention Example 15.

[0035] Figure 3 is a differential scanning calorimetry (DSC) analysis graph of the steel plate manufactured in Comparative Example 3.

[0036] The terms first, second, and third, etc., are used to describe, but are not limited to, various parts, components, regions, layers, and / or sections. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0037] 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.

[0038] 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.

[0039] Also, unless otherwise stated, % means weight%, and 1 ppm is 0.0001 weight%.

[0040] 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.

[0041] 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.

[0042] 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.

[0043]

[0044] 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.

[0045] Below, the reasons for the limitation of the components of non-oriented electrical steel sheets are explained.

[0046]

[0047] Si: 2.50 to 4.50 wt%

[0048] Silicon (Si) is a major element added to increase the resistivity of steel and reduce eddy current loss among iron losses, and is added to secure low iron loss characteristics, especially in the high-frequency range. If too little Si is added, the iron loss improvement effect may be insufficient. If too much Si is added, the magnetic flux density may decrease significantly and the possibility of B2, DO3 regular formation in local areas may increase. More specifically, it may contain 2.70 to 4.30 wt%. More specifically, it may contain 3.00 to 4.00 wt%.

[0049]

[0050] Mn: 0.10 to 2.50 wt%

[0051] Manganese (Mn), along with silicon (Si) and aluminum (Al), is an element that increases resistivity and reduces iron loss. However, if the amount added is too small, it can form fine sulfides, which can be detrimental to texture control during subsequent annealing heat treatment after hot rolling. If the amount added is excessive, not only will the magnetic flux density decrease significantly, but the risk of B2 and DO3 regularization in localized areas of the hot-rolled steel sheet can also increase. More specifically, it can be included in an amount of 0.30 to 2.30 wt%. More specifically, it can be included in an amount of 0.50 to 2.10 wt%.

[0052]

[0053] Al: 1.00 to 2.50 wt%

[0054] Aluminum (Al) is an element added because it plays an important role in reducing iron loss by increasing resistivity together with Si, and also reduces magnetic anisotropy, thereby reducing magnetic deviation in the rolling direction and the direction perpendicular to the rolling. However, if the amount added is small, the effect of reducing iron loss is not significant, and if the amount added is too large, the magnetic flux density is greatly inferior, and the risk of B2, DO3 regular formation in local areas of the hot-rolled steel sheet may increase. More specifically, it may contain 1.05 to 2.30 wt%. More specifically, it may contain 1.10 to 2.25 wt%.

[0055] A hot-rolled steel sheet for non-oriented electrical steel according to one embodiment of the present invention can satisfy the following equation 1.

[0056] [Formula 1]

[0057] 0.6≤([Al]+[Mn]) / [Si]≤1

[0058] (In Equation 1, [Al], [Mn], and [Si] represent the contents (weight %) of Al, Mn, and Si, respectively.)

[0059] 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 an increase in the amount of Si added 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 0.63 to 0.99.

[0060]

[0061] A hot-rolled steel sheet for non-oriented electrical steel 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%).

[0062] P: 0.002 to 0.02 wt%

[0063] Phosphorus (P) improves the grain structure of steel by segregating between grain boundaries and surfaces. However, if the amount added is insufficient, its effect may be minimal. Excessive addition of P can inhibit grain growth, thereby reducing iron loss, and reduce productivity by causing grain boundary segregation, thereby reducing rollability. More specifically, P may be added in an amount of 0.003 to 0.015 wt%.

[0064] C: 0.005 wt% or less

[0065] Carbon (C) combines with Ti, Nb, etc. to form carbides, thereby lowering magnetism. In addition, when processed into an electrical product in the final product and used, the iron loss increases due to magnetic aging, thereby reducing the efficiency of the electrical device. Therefore, it can be limited to 0.005 wt% or less. More specifically, C can be included in an amount of 0.0001 to 0.003 wt%.

[0066] S: 0.0005 to 0.005 wt%

[0067] 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 desirable to add as little as possible. However, if added in an amount less than 0.0005 wt%, it is rather detrimental to the formation of texture, and the formation of fine sulfides may be promoted, which may reduce magnetism. If too much sulfur is added, the magnetism may be deteriorated due to the increase in sulfides. More specifically, S may be included in an amount of 0.0010 to 0.0045 wt%.

[0068] Ti: 0.005 wt% or less

[0069] Titanium (Ti) forms fine carbides and nitrides by combining with C and N, which inhibits grain growth and lowers magnetic flux density. As more is added, the aggregate structure becomes lower due to the increased carbides and nitrides, which may result in poor magnetism. More specifically, Ti may be included in an amount of 0.0001 to 0.005 wt%. More specifically, Ti may be included in an amount of 0.0001 to 0.003 wt%.

[0070] N: 0.005 wt% or less

[0071] Nitrogen (N) is an element harmful to magnetism, as it forms nitrides by strongly combining with Al, Ti, Nb, etc., thereby inhibiting grain growth, and therefore may be included in small amounts. More specifically, N may be included in an amount of 0.0001 to 0.0030 wt%.

[0072] A hot-rolled steel sheet for non-oriented electrical steel 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.

[0073] Sn and Sb

[0074] Tin (Sn) and antimony (Sb) are elements that improve the texture and can be added to further improve magnetic properties. More specifically, the alloy may contain 0.005 to 0.200 wt% Sn or 0.005 to 0.200 wt% Sb.

[0075] Bi, Pb, Ge, and As

[0076] Bismuth (Bi), lead (Pb), germanium (Ge), and arsenic (As) further improve the magnetic flux density when added additionally. If they are added appropriately, the aforementioned effects can be additionally obtained, but if they are included in too much, a large amount of segregation may occur, which may inhibit grain growth and deteriorate the magnetic flux density and iron loss. More specifically, one or two or more kinds of Bi, Pb, Ge, and As may be included individually or in a combined amount of 0.200 wt% or less. More specifically, one or two or more kinds of Bi, Pb, Ge, and As may be included individually or in a combined amount of 0.0001 to 0.200 wt%. More specifically, one or two or more kinds of Bi, Pb, Ge, and As may be included individually or in a combined amount of 0.001 to 0.100 wt%.

[0077]

[0078] A hot-rolled steel sheet for non-oriented electrical steel 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%).

[0079] Cu: 0.005 to 0.200 wt%

[0080] Copper (Cu) may be added for reasons such as improving magnetism, but it may react with impurity elements to form fine sulfides, carbides, and nitrides, which may have a detrimental effect on magnetism. More specifically, 0.01 to 0.10 wt% of Cu may be included.

[0081] Cr: 0.01 to 0.50 wt%

[0082] 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%.

[0083] Ni: 0.05 wt% or less

[0084] Nickel (Ni) may be added for reasons such as improving magnetism, but it may react with impurity elements to form fine sulfides, carbides, and nitrides, which may have a detrimental effect on magnetism. More specifically, Ni may be included in an amount of 0.001 to 0.03 wt%.

[0085] Zn: 0.01 wt% or less

[0086] 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%.

[0087] Co: 0.05 wt% or less

[0088] Cobalt (Co) does not form fine precipitates that reduce the magnetism of steel sheets, but it increases high-temperature strength and can cause poor coil shape after hot rolling. More specifically, Co may be included in an amount of 0.001 to 0.02 wt%.

[0089]

[0090] A hot-rolled steel sheet for non-oriented electrical steel 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%).

[0091] Mo: 0.030 wt% or less

[0092] 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%.

[0093] B: 0.0050 wt% or less

[0094] 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%.

[0095] V: 0.0050 wt% or less

[0096] 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%.

[0097] Ca: 0.0050 wt% or less

[0098] 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.

[0099] Nb: 0.0050 wt% or less

[0100] 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%.

[0101] Zr: 0.0050 wt% or less

[0102] 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%.

[0103] Te: 0.0100 wt% or less

[0104] 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%.

[0105] Mg: 0.0050 wt% or less

[0106] 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%.

[0107]

[0108] 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).

[0109]

[0110] In a hot-rolled steel sheet for non-oriented electrical steel according to one embodiment of the present invention, the peak of the heat flow curve measured during the heating process using a differential scanning calorimeter (DSC) exists at 325 to 475°C.

[0111] In steel grades with high Si, Al, and Mn contents, there is a high possibility that B2 and DO3 ordered phases will be formed in areas where these elements are locally concentrated in the hot-rolled steel sheet. In one embodiment of the present invention, it was found that when manufacturing a non-oriented electrical steel sheet with a hot-rolled steel sheet with a high fraction of ordered phase, it is disadvantageous to secure magnetic flux density. If an ordered phase exists, the formation of a texture that is disadvantageous to securing magnetic flux density may be promoted at the interface between the ordered and irregular phases during subsequent deformation and annealing processes. Meanwhile, the fraction of the ordered phase at room temperature can be measured by Differential Scanning Calorimetry (DSC). When the steel sheet is heated at a constant rate and the heat flow curve according to temperature is observed, the presence or absence of the ordered phase in the material before heating and the relative fraction difference can be determined by observing the peak of the exothermic reaction in which the irregular phase is transferred to the ordered phase. In other words, the lower the fraction of the ordered phase at room temperature, the more the peak of the corresponding curve exists at a relatively low temperature. This can be attributed to the phenomenon that even hot-rolled steel sheets with a low fraction of regular phases controlled through an appropriate cooling method can generate regular phases when heated, and that the lower the fraction of regular phases at room temperature, the more regular phases are generated at relatively low temperatures. In one embodiment of the present invention, as a result of analyzing the DSC peak and the magnetic flux density of the final electrical steel sheet, it was confirmed that the magnetic flux density (B50) was 1.60 T or higher when the peak was 475 ℃ or lower. Although the lower limit of the peak is better, in order to satisfy the iron loss proposed in the present invention, a certain level of Si, Mn, and Al content must be added, and therefore, it needs to be 325 ℃ or higher. Therefore, in the present invention, the peak of the heat flow curve measured during the heating process by Differential Scanning Calorimetry (DSC) of the hot-rolled steel sheet can be 325 to 475 ℃. More specifically, it can be 330 to 465 ℃. More specifically, it can be between 340 and 460°C.The method of analyzing DSC is to remove the scale existing on the surface of the hot-rolled steel plate, and then measure the heat flow during the heating process at a heating rate of 10℃ / min from 600 to 700℃ using DSC, and measure the temperature at which a peak is generated during the process. At this time, the peak is determined as the shape of the heat flow curve, that is, the position where the graph changes from an increasing to a decreasing trend.

[0112] A hot-rolled steel sheet for non-oriented electrical steel according to one embodiment of the present invention 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.

[0113]

[0114] 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; and a step of cooling the hot-rolled steel sheet.

[0115] Below, each step is explained in detail.

[0116] First, the slab is hot rolled.

[0117] Since the alloy composition of the slab has been described in the alloy composition of the hot-rolled steel sheet for non-oriented electrical steel mentioned above, a duplicate description will be omitted. Since the alloy composition does not substantially change during the manufacturing process of the hot-rolled steel sheet, the alloy composition of the hot-rolled steel sheet and the slab are substantially the same. Furthermore, since the alloy composition does not substantially change during the manufacturing process of the non-oriented electrical steel sheet after the manufacturing of the hot-rolled steel sheet, the alloy composition of the hot-rolled steel sheet and the final manufactured non-oriented electrical steel sheet are substantially the same.

[0118] Specifically, the slab contains, by weight, 2.5 to 4.5% Si, 0.1 to 2.5% Mn, 1.0 to 2.5% Al, the remainder being Fe and other unavoidable impurities.

[0119] As for other additional elements, they have been described in the alloy composition of hot-rolled steel sheets for non-oriented electrical steel sheets, so any duplicate description will be omitted.

[0120] 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.

[0121] 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.

[0122] The step of manufacturing the hot rolled sheet may include a step of finish rolling at a temperature of 850°C or higher.

[0123] 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.

[0124] After finishing rolling, the hot rolled steel sheet can be cooled before coiling. In one embodiment of the present invention, by controlling the cooling rate and coiling temperature after hot rolling, the regular fraction can be reduced.

[0125] The cooling step can be performed at a temperature range of 400 to 100°C at a rate of 30°C / sec or more. In steels with high Si, Al, and Mn contents, it is known that regular phases are generated in the range of 400 to 100°C during cooling after hot rolling. If the range is cooled at a rate of 30°C / sec or more, it is effective in suppressing the fraction of regular phases in the hot-rolled steel sheet. If the cooling rate is too high, a problem of shape defects due to a difference in cooling rate between each section of the hot-rolled steel sheet may occur. More specifically, the cooling can be performed at a rate of 30°C / sec to 100°C / sec. More specifically, the cooling can be performed at a rate of 31 to 90°C / sec. The cooling rate may be an average cooling rate in the temperature range of 400 to 100°C.

[0126] The coiling step of the hot-rolled steel sheet can be performed at a temperature of 100°C or lower. If rapid cooling is performed after coiling, a material deviation problem may occur due to a difference in cooling speed between the inner and outer coils. In one embodiment of the present invention, this problem can be solved by coiling the hot-rolled steel sheet at a temperature of 100°C or lower. The method of cooling the hot-rolled steel sheet can use a method such as air blowing or water cooling. More specifically, the coiling step can be performed at 70°C to 90°C. If the coiling temperature is low, the problem of excessive cooling deviation in the width direction due to excessively rapid cooling of the edge of the hot-rolled steel sheet may occur during the process of cooling the hot-rolled steel sheet to the coiling temperature. However, this can be solved by controlling the amount of air blown to the edge, the amount of water, etc. to suppress excessive cooling.

[0127] Alternatively, cooling can be performed after the coiling step of the hot-rolled steel sheet. Even then, cooling can be performed at the aforementioned cooling rate. To ensure this cooling rate, the coiled coil can be immersed in a water bath for cooling.

[0128]

[0129] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention comprises the steps of preparing a hot-rolled steel sheet containing, by weight %, 2.5 to 4.5% of Si, 0.1 to 2.5% of Mn, 1.0 to 2.5% of Al, the remainder being Fe and other unavoidable impurities, and having a peak in a heat flow curve measured during a heating process using a differential scanning calorimeter (DSC) at 325 to 475°C; cold-rolling the hot-rolled steel sheet to manufacture a cold-rolled steel sheet; and annealing the cold-rolled steel sheet.

[0130] Since hot-rolled steel plates and their manufacturing methods have been described above, redundant descriptions will be omitted.

[0131] 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 850 to 1100°C. If the annealing temperature is too low, the recrystallized structure may not form 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 deteriorate, and the deformation of the sheet shape may deteriorate the rolling workability. More specifically, the temperature range can be 830 to 1170°C. The soaking time can be 15 to 180 seconds. Hot-rolled sheet annealing can be omitted if necessary.

[0132] 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 0.3 mm. More specifically, it can be 0.15 to 0.25 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.

[0133] Cold rolling can be performed as a single pass, if necessary, or as two passes with an intermediate annealing. In either case, the final reduction ratio should be between 30 and 80% to ensure proper grain structure control and ensure excellent magnetic properties.

[0134] Next, the cold-rolled steel sheet is annealed. In the annealing process for cold-rolled steel, the annealing temperature is not particularly limited as long as it is the temperature typically applied to non-oriented electrical steel sheets. The iron loss of non-oriented electrical steel sheets is closely related to grain size. Iron loss in non-oriented electrical steel sheets can be divided into hysteresis loss and eddy current loss. Hysteresis loss decreases with increasing grain size, while eddy current loss increases with increasing grain size. Therefore, there exists an optimal grain size at which the sum of hysteresis loss and eddy current loss is minimized. Therefore, it is important to determine and apply an annealing temperature that secures the optimal grain size, which can be between 850 and 1100°C. If the annealing temperature is too low, the grains become too fine, increasing hysteresis loss. If the annealing temperature is too high, the grains become too coarse, increasing eddy current loss and resulting in poor iron loss. More specifically, annealing can be performed at 900 to 1050°C.

[0135] After the cold-rolled sheet annealing step, a step of forming an insulating film may be further included to ensure insulation and corrosion resistance of the steel sheet. Since the insulating film is widely known, a detailed description thereof will be omitted.

[0136]

[0137] The non-oriented electrical steel sheet manufactured in one embodiment of the present invention has excellent magnetic flux density and, at the same time, excellent high-frequency iron loss. Specifically, the non-oriented electrical steel sheet according to one embodiment of the present invention has excellent 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.

[0138] B 50 refers to the magnetic flux density induced in a magnetic field of 5000 A / m.

[0139] W 10 / 400 is the iron loss when a magnetic flux density of 1.0 T is induced at a frequency of 400 Hz.

[0140] In one embodiment of the present invention, B 50 and W10 / 400 The 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.

[0141] 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. More specifically, it may be 65 to 90.

[0142]

[0143] 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.

[0144]

[0145] Example 1

[0146] A slab was manufactured with the composition shown in Table 1 below. The remainder is Fe. The slab was heated to 1180°C, hot-rolled to a thickness of 2.1 mm, and then cooled in the temperature range of 400 to 100°C at the cooling rate listed in Table 2 below. Thereafter, it was coiled at the coiling temperature listed in Table 2 below. When the coiling temperature exceeded 400°C, the slab was coiled before cooling and immersed in a water bath to cool in the temperature range of 400 to 100°C at the cooling rate listed in Table 2 below.

[0147] After hot rolling, the cooled hot-rolled steel sheet was subjected to surface scale removal, and the heat flow was measured during the heating process at a heating rate of 10℃ / s using Differential Scanning Calorimetry (DSC). The temperature at which peaks were generated was measured and summarized in Table 2.

[0148] The manufactured hot-rolled steel sheet was hot-rolled and annealed at 1000°C. Then, the hot-rolled sheet annealed above was pickled, cold-rolled to a thickness of 0.2 mm, and then finally cold-rolled at 1000°C.

[0149] After machining the magnetic measurement specimen from the final product of cold-rolled sheet annealed, the resistivity and iron loss W at room temperature 10 / 400 and magnetic flux density B 50 The results were also shown in Table 2 below. Meanwhile, in this experiment, the iron loss W 10 / 400 It represents the average loss (W / Kg) in the rolling direction and the direction perpendicular to the rolling when a magnetic flux density of 1.0 Tesla is induced at a frequency of 400 Hz, and the magnetic flux density B 50 It represents the size (Tesla) of the magnetic flux density induced when a magnetic field of 5000 A / m is applied.

[0150] (Wt%) CSiMnPSAlTiInvention Example 10.00134.201.820.0130.00341.530.0022Invention Example 20.00162.960.740.0030.00311.330.0007Invention Example 30.00373.652.090.0050.00081.230.0042Invention Example 40.00123.090.700.0050.00142.190.0026Invention Example 50.00212.891.710.0150.00371.160.0031Invention Example 60.00364.221.570.0050.00241.320.00 35 Invention Example 70.00373.661.750.0040.00361.770.0017 Invention Example 80.00204.021.030.0110.00081.890.0038 Invention Example 90.00293.320.510.0090.00392.040.0023 Invention Example 10 0.00383.161.000.0050.00401.050.0007Invention Example 110.00183.600.730.0050.00292.220.0034Invention Example 120.00253.700.600.0090.00242.380.0034Invention Example 130.001 43.332.080.0120.00321.130.0034Invention Example 140.00123.061.310.0150.00371.600.0024Invention Example 150.00253.400.770.0110.00421.970.0007Comparative Example 10.00161.96 0.740.0030.00311.330.0007Comparative Example 20.00211.891.710.0150.00371.160.0031Comparative Example 30.00134.521.820.0130.00341.530.0022Comparative Example 40.00364.511.570.0 050.00241.320.0035Comparative Example 50.00293.320.080.0090.00392.040.0023Comparative Example 60.00253.700.070.0090.00242.380.0034Comparative Example 70.00143.332.520.0120.003 21.130.0034Comparative Example 80.00123.252.530.0080.00270.750.0028Comparative Example 90.00383.161.000.0050.00400.980.0007Comparative Example 100.00212.891.710.0150.00370.970.0031Comparative Example 110.00253.700.600.0090.00242.520.0034Comparative Example 120.00183.600.730.0050.00292.510.0034Comparative Example 130.00134.201.820.0130.00341.530.0 022Comparative Example 140.00162.960.740.0030.00311.330.0007Comparative Example 150.00373.652.090.0050.00081.230.0042Comparative Example 160.00123.090.700.0050.00142.190.0026Comparative Example 170.00212.891.710.0150.00371.160.0031Comparative Example 180.00364.221.570.0050.00241.320.0035Comparative Example 190.00373.661.750.0040.00361.770.001 7Comparative Example 200.00204.021.030.0110.00081.890.0038Comparative Example 210.00293.320.510.0090.00392.040.0023Comparative Example 220.00383.161.000.0050.00401.050.0007.

[0151] Hot rolled steel sheet 400~100℃ Cooling speed (℃ / sec) Coiling temperature (℃) Water bath cooling DSC Peak position (℃) Invention example 140620○421 Invention example 251675○452 Invention example 349699○471 Invention example 459673○405 Invention example 572666○342 Invention example 678572○400 Invention example 752575○428 Invention example 86292X341 Invention example 93174X345 Invention Example 103491X406 Invention Example 114376X363 Invention Example 124181X446 Invention Example 135472X459 Invention Example 147977X375 Invention Example 157884X386 Comparative Example 170650○460 Comparative Example 25297X332 Comparative Example 372656○492 Comparative Example 46682X 485Comparative Example 551656○351Comparative Example 64398X334Comparative Example 745604○478Comparative Example 84584X482Comparative Example 979691○400Comparative Example 107397X450Comparative Example 1178585○480Comparative Example 127482X483Comparative Example 1322610X486Comparative Example 1419553X486Comparison Example 1521557X486Comparison Example 1629658X480Comparison Example 1719575X486Comparison Example 1820145X487Comparison Example 1923145X481Comparison Example 2019144X481Comparison Example 2127141X480Comparison Example 2228149X487

[0152] Resistivity (μΩcm)W 10 / 400(W / Kg)B50(T)Invention Example 187.98.31.61Invention Example 265.510.11.63Invention Example 379.89.11.62Invention Example 476.59.81.62Invention Example 568.39.71.61Invention Example 684.39.31.62Invention Example 784.18.81.61Invention Example 885.49.01.62Invention Example 976.39.41.63 Honor 1066.210.31.63 Invention Example 1182.78.41.61 Invention Example 1284.98.01.61 Invention Example 1375.09.81.62 Invention Example 1472.910.11.63 Invention Example 1577.99.11.62 Comparative Example 162.512.11.63 Comparative Example 262.712.31.62 Comparative Example 388.98.21.56 Comparative Example 485 .19.11.55Comparative Example 562.512.31.65Comparative Example 661.212.51.64Comparative Example 774.89.91.59Comparative Example 872.610.01.58Comparative Example 962.812.11.64Comparative Example 1062.512.31.63Comparative Example 1186.18.21.58Comparative Example 1284.38.31.57Comparative Example 1387.78.1 1.57Comparative Example 1464.39.71.55Comparative Example 1578.59.31.56Comparative Example 1675.89.61.55Comparative Example 1769.310.11.56Comparative Example 1885.29.61.52Comparative Example 1984.38.91.52Comparative Example 2084.89.21.55Comparative Example 2175.39.31.52Comparative Example 2273.510.51.56

[0153] As shown in Tables 1 to 3, in the case of the invention examples in which the steel composition is appropriately controlled and the cooling rate and coiling temperature after hot rolling are appropriately controlled, the regular fraction is small, so that the DSC peak temperature exists in an appropriate range, and it can be confirmed that the non-oriented electrical steel sheet manufactured through this has excellent magnetism.

[0154] Comparative Examples 1 to 4 show poor magnetism due to insufficient Si content. Comparative Examples 1 and 2 show poor resistivity and iron loss due to insufficient Si content, while Comparative Examples 3 and 4 show excessive Si content, resulting in a large amount of regular phase formation and a DSC peak at a high temperature. This confirms poor magnetic flux density.

[0155] Comparative Examples 5 to 8 show poor magnetism due to insufficient Mn content. Comparative Examples 5 and 6 show poor resistivity and iron loss due to insufficient Mn content, while Comparative Examples 7 and 8 show excessive Mn content, resulting in the formation of a large amount of regular phase and the formation of a DSC peak at a high temperature. This confirms poor magnetic flux density.

[0156] Comparative Examples 9 to 12 show poor magnetism due to insufficient Al content. Comparative Examples 9 and 10 show poor resistivity and iron loss due to too little Al, and Comparative Examples 11 and 12 show excessive Al content, resulting in a large amount of regular phase formation and a DSC peak formation at a high temperature. This confirms poor magnetic flux density.

[0157] Comparative Examples 13 to 22 show that the cooling rate is not adequately secured, resulting in a large amount of regular phase formation and the formation of DSC peaks at high temperatures. This confirms that the magnetic flux density is inferior.

[0158]

[0159] 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

Contains Si: 2.5 to 4.5% by weight, Mn: 0.1 to 2.5%, Al: 1.0 to 2.5%, the remainder being Fe and other unavoidable impurities. A hot-rolled steel sheet for non-oriented electrical steel, the peak of the heat flow curve measured during the heating process by differential scanning calorimetry (DSC) existing at 325 to 475°C. In the first paragraph, A hot rolled steel sheet for non-oriented electrical steel 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 hot-rolled steel sheet for non-oriented electrical steel 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 hot-rolled steel sheet for non-oriented electrical steel further containing 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 hot-rolled steel sheet for non-oriented electrical steel 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, A hot-rolled steel sheet for non-oriented electrical steel 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, Hot-rolled steel sheet for non-oriented electrical steel having a resistivity (ρ) of 63 μΩcm or more at 25℃. A step of manufacturing a hot-rolled steel sheet by hot-rolling a slab containing Si: 2.5 to 4.5% by weight, Mn: 0.1 to 2.5%, Al: 1.0 to 2.5%, the remainder Fe, and other inevitable impurities; and Comprising a step of cooling the hot rolled steel plate, A method for manufacturing a hot-rolled steel sheet for non-oriented electrical steel, wherein the cooling step is performed at a temperature range of 400 to 100°C at a rate of 30°C / sec or more. In Article 8, After the step of cooling the hot-rolled steel sheet, a step of coiling the hot-rolled steel sheet is included. A method for manufacturing a hot-rolled steel sheet for non-oriented electrical steel, wherein the step of coiling the hot-rolled steel sheet is performed at a temperature of 100°C or less. In Article 8, A method for manufacturing a hot rolled steel sheet for non-oriented electrical steel, wherein the cooling step is performed at a temperature range of 400 to 100°C at a rate of 30°C / sec to 100°C / sec. In Article 8, A method for manufacturing a hot-rolled steel sheet for non-oriented electrical steel, 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 8, A method for manufacturing a hot-rolled steel sheet for non-oriented electrical steel, 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 8, A method for manufacturing a hot-rolled steel sheet for non-oriented electrical steel, wherein the above slab further contains 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 8, A method for manufacturing a hot rolled steel sheet for non-oriented electrical steel, 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%). Contains Si: 2.5 to 4.5% by weight, Mn: 0.1 to 2.5%, Al: 1.0 to 2.5%, the remainder being Fe and other unavoidable impurities. A step for preparing a hot-rolled steel sheet in which the peak of the heat flow curve measured during the heating process by differential scanning calorimetry (DSC) exists at 325 to 475°C; A step of manufacturing a cold rolled steel sheet by cold rolling the hot rolled steel sheet; and A method for manufacturing a non-oriented electrical steel sheet, comprising a step of annealing the cold rolled steel sheet. In Article 15, The non-oriented electrical steel sheet manufactured above has a core loss (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.

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