Non-oriented electrical steel sheet, hot-rolled steel sheet for 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 to 5.0% of Si, 0.2 to 2.0% of Al, and 0.5 to 2.0% of Mn, and the balance of Fe and inevitable impurities, and satisfies Equation 1. [Equation1] -1.2 ≤ VA + VB + VC - VD ≤ 3.0 (In equation 1, VA, VB, VC, and VD represent area fractions (%) of crystal grains having grain sizes of 2 μm or more and orientations within 15° from (001)[110], (110)[001], (100)[001], and (111)[1-10], respectively.

Description

Non-oriented electrical steel sheet, hot-rolled steel sheet for non-oriented electrical steel sheet, and method of manufacturing the same

[0001] One embodiment of the present invention relates to a non-oriented electrical steel sheet, a hot-rolled steel sheet for 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 with improved magnetism, a hot-rolled steel sheet for a non-oriented electrical steel sheet, and a method for manufacturing the same, by appropriately controlling the reduction rate of each pass of finishing rolling during hot rolling to appropriately control the texture within the hot-rolled steel sheet and the non-oriented electrical steel sheet.

[0002] Non-oriented electrical steel is primarily used in motors that convert electrical energy into mechanical energy, and excellent magnetic properties are required to achieve high efficiency in this process. In particular, with the recent rise in interest in eco-friendly vehicles driven by motors instead of internal combustion engines, the demand for non-oriented electrical steel used as core materials for drive motors is increasing, and to meet this demand, non-oriented electrical steel with excellent magnetic properties and strength is required.

[0003] The magnetic properties of non-oriented electrical steel are primarily evaluated based on iron loss and magnetic flux density. Iron loss refers to the energy loss occurring at a specific magnetic flux density and frequency, while magnetic flux density refers to the degree of magnetization obtained under a specific magnetic field. Lower iron loss allows for the manufacture of motors with higher energy efficiency under the same conditions, whereas higher magnetic flux density enables motor miniaturization or reduced copper loss. Therefore, by utilizing non-oriented electrical steel with low iron loss and high magnetic flux density, drive motors with excellent efficiency and torque can be produced, 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 motor's operating conditions. A widely used general standard for evaluating the characteristics of non-oriented electrical steel sheets used in motors is W15 / 50, which represents the iron loss when a 1.5T magnetic field is applied at a commercial frequency of 50Hz. However, for non-oriented electrical steel sheets with a thickness of 0.35mm or less used in drive motors for eco-friendly vehicles, magnetic properties are often critical at low fields of 1.0T or less and high frequencies above 400Hz; therefore, W 10 / 400 The characteristics of non-oriented electrical steel sheets are often evaluated based on iron loss.

[0005] Among the important characteristics of non-oriented electrical steel sheets, the most basic and efficient methods to reduce iron loss include increasing the addition of elements with high resistivity, such as Si, Al, and Mn, or reducing the thickness of the steel sheet. Increasing the addition of Si, Al, and Mn increases the resistivity of the steel, thereby reducing eddy current losses among the iron losses of non-oriented electrical steel sheets and effectively reducing iron loss. Since eddy current losses account for a larger proportion of iron loss in the case of high-frequency iron loss, this method can be very effective for reducing high-frequency iron loss. However, the effect varies depending on the addition ratio. Furthermore, as the amount of alloying elements increases, magnetic flux density deteriorates, and the increase in material strength due to increased alloy content causes material brittleness, which impairs workability. Therefore, to secure excellent iron loss, magnetic flux density, and workability, it is necessary to properly control the addition ratio between the appropriate amount of Si, Al, and Mn.

[0006] Ultimately, there is an urgent need for technology to manufacture electrical steel sheets with good workability while increasing the addition of elements with high resistivity, such as Si, Al, and Mn.

[0007] 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 a non-oriented electrical steel sheet. Specifically, one embodiment of the present invention provides a hot-rolled steel sheet for non-oriented electrical steel in which the fraction of regular phases within the hot-rolled steel sheet is suppressed by appropriately controlling the cooling rate after hot rolling, a method for manufacturing the same, and a method for manufacturing a non-oriented electrical steel sheet.

[0008] A non-oriented electrical steel sheet according to one embodiment of the present invention comprises, in weight%, Si: 1.5 to 5.0%, Al: 0.2 to 2.5%, Mn: 0.5 to 2.0%, the remainder being Fe and unavoidable impurities, and satisfies Formula 1 below.

[0009] [Equation 1]

[0010] -1.2≤VA+VB+VC-VD≤3.0

[0011] (In Equation 1, VA, VB, VC, and VD represent the area fraction (%) of crystal grains with a diameter of 2 μm or more having orientations within 15° from the (001)

[0110] , (110)

[0001] , (100)

[0001] , and (111)[1-10] orientations, respectively.)

[0012] A non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following conditions for ratios of hysteresis loss, eddy current loss, and abnormal eddy current loss of W10 / 100, W10 / 400, and W10 / 1000.

[0013] The iron loss ratio of W10 / 100 is hysteresis loss: 60 to 80%, eddy current loss: 5 to 15%, abnormal eddy current loss: 10 to 30%

[0014] The iron loss ratio of W10 / 400 is hysteresis loss: 35 to 65%, eddy current loss: 15 to 30%, abnormal eddy current loss: 15 to 35%

[0015] The iron loss ratio of W10 / 1000 is hysteresis loss: 30 to 50%, eddy current loss: 30 to 50%, abnormal eddy current loss: 20 to 40%.

[0016] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of P: 0.1 wt% or less, C: 0.005 wt% or less, S: 0.005 wt% or less, Ti: 0.005 wt% or less, and N: 0.005 wt% or less.

[0017] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include 0.005 to 0.200 weight% of one or more of Sn, Sb, Bi, Pb, Ge, and As, respectively or in their combined amount.

[0018] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

[0019] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of Mo: 0.03 wt% or less, B: 0.0050 wt% or less, V: 0.0050 wt% or less, Ca: 0.0050 wt% or less, Nb: 0.0050 wt% or less, Zr: 0.005 wt% or less, Te: 0.01 wt% or less, and Mg: 0.0050 wt% or less.

[0020] A hot-rolled steel sheet for manufacturing non-oriented electrical steel sheets according to one embodiment of the present invention comprises, in weight percent, Si: 1.5 to 5.0%, Al: 0.2 to 2.5%, and Mn: 0.5 to 2.0%, and the remainder is Fe and unavoidable impurities; comprises a microstructure in which the proportion of a region with a Grain Orientation Spread value of 0.8 or less analyzed by EBSD of 2.0 or less is 15% or more; and has a non-notched room temperature shock absorption energy value of 50 J / cm² 2 That is all.

[0021] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention comprises: a step of manufacturing a hot-rolled steel sheet by hot-rolling a slab comprising, in weight%, Si: 1.5 to 5.0%, Al: 0.2 to 2.5%, Mn: 0.5 to 2.0%, and the remainder being Fe and unavoidable impurities; a step of manufacturing a cold-rolled sheet by cold-rolling the hot-rolled steel sheet; and a cold-rolled sheet annealing step of annealing the cold-rolled sheet.

[0022] The steps for manufacturing hot-rolled steel sheets include a rough rolling step and a finishing rolling step, and the finishing rolling step includes three or more rolling passes, and when the last pass of the finishing rolling step is called the nth pass, the reduction rates of the n-2nd, n-1st, and nth passes are as follows.

[0023] 21% ≤ n-2th reduction rate ≤ 46%

[0024] 18% ≤ n-1th reduction rate ≤ 39%

[0025] 7% ≤ nth reduction rate ≤ 25%

[0026] The slab may further include one or more of P: 0.1 wt% or less, C: 0.005 wt% or less, S: 0.005 wt% or less, Ti: 0.005 wt% or less, and N: 0.005 wt% or less.

[0027] The slab may further contain 0.005 to 0.200 weight% of one or more of Sn, Sb, Bi, Pb, Ge, and As, either individually or in their combined amount.

[0028] The slab may further include one or more of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

[0029] The slab may further include one or more of Mo: 0.03 wt% or less, B: 0.0050 wt% or less, V: 0.0050 wt% or less, Ca: 0.0050 wt% or less, Nb: 0.0050 wt% or less, Zr: 0.005 wt% or less, Te: 0.01 wt% or less, and Mg: 0.0050 wt% or less.

[0030] The hot-rolled steel sheet contains a microstructure in which the proportion of regions with a Grain Orientation Spread value of 0.8 or less, analyzed by EBSD, is 15% or more, and the notched room-temperature impact absorption energy value is 50 J / cm² 2 It could be more than that.

[0031] A non-oriented electrical steel sheet according to one embodiment of the present invention has improved texture characteristics and simultaneously exhibits excellent iron loss at low and high frequencies.

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

[0034] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0035] When it is stated that one part is "on" or "on" another part, it may be directly on or on the other part, or another part may be involved in between. In contrast, when it is stated that one part is "directly on" another part, no other part is interposed in between.

[0036] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0037] In one embodiment of the present invention, the meaning of including additional elements is that the remainder of iron (Fe) is replaced by an amount of the additional element.

[0038] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0039] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0040]

[0041] A non-oriented electrical steel sheet according to one embodiment of the present invention comprises, in weight%, Si: 1.5 to 5.0%, Al: 0.2 to 2.5%, Mn: 0.5 to 2.0%, and the remainder being Fe and unavoidable impurities.

[0042] Below, we will explain the reason for limiting the composition of non-oriented electrical steel sheets.

[0043]

[0044] Si: 1.5 to 5.0 wt%

[0045] Silicon (Si) is a major element added to increase the resistivity of steel to reduce eddy current losses among iron losses, and is added to secure low iron loss characteristics, particularly in the high-frequency region. If too little Si is added, the effect of improving iron loss may be insufficient. If too much Si is added, the magnetic flux density decreases significantly and machinability may decline. More specifically, it may be included in an amount of 1.6 to 4.9 weight%.

[0046]

[0047] Al: 0.2 to 2.5 wt%

[0048] 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 rolling perpendicular direction. 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 significantly inferior and workability may also be inferior. More specifically, it may be included in an amount of 0.3 to 2.0 weight%.

[0049]

[0050] Mn: 0.5 to 2.0 wt%

[0051] Manganese (Mn) is an element that, along with Si and Al, increases resistivity and lowers iron loss. However, if the amount added is too small, it forms fine sulfides, which may be disadvantageous for texture control during subsequent annealing heat treatment after hot rolling. If the amount added is excessive, not only is the magnetic flux density significantly reduced, but the risk of formation according to the B2 and DO3 rules may also increase in localized areas of the hot-rolled steel sheet. More specifically, it may be included in an amount of 0.7 to 1.9 weight%.

[0052]

[0053] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of P: 0.1 wt% or less, C: 0.005 wt% or less, S: 0.005 wt% or less, Ti: 0.005 wt% or less, and N: 0.005 wt% or less.

[0054] P: 0.1 wt% or less

[0055] Phosphorus (P) has the effect of improving the texture of steel as a grain boundary and surface segregation element. However, if too much phosphorus is added, it inhibits grain growth, thereby reducing iron loss, and reduces rolling performance due to grain boundary segregation, which may also reduce productivity. More specifically, it may further contain 0.005 to 0.050 weight% of P.

[0056] C: 0.005 wt% or less

[0057] Carbon (C) combines with Ti, Nb, etc. to form carbides, thereby degrading magnetism, and when used after processing from the final product into an electrical product, iron loss increases due to magnetic aging, which reduces the efficiency of the electrical device; therefore, it can be limited to 0.005 weight% or less. More specifically, C may be included in an amount of 0.0001 to 0.003 weight%.

[0058] S: 0.005 wt% or less

[0059] 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 it in the lowest possible amount. If too much sulfur is added, the magnetic properties may deteriorate due to an increase in sulfides. More specifically, S may be included in an amount of 0.0005 to 0.0040 weight%.

[0060] Ti: 0.005 wt% or less

[0061] Titanium (Ti) forms fine carbides and nitrides by bonding with C and N, thereby inhibiting grain growth and degrading magnetic flux density; as more is added, the texture also degrades due to the increased carbides and nitrides, which can lead to poor magnetism. More specifically, it may contain 0.0001 to 0.005 weight% of Ti. More specifically, it may contain 0.0001 to 0.003 weight% of Ti.

[0062] N: 0.005 wt% or less

[0063] Nitrogen (N) is an element harmful to magnetism, as it forms nitrides by strongly bonding with Al, Ti, Nb, etc., thereby inhibiting grain growth, so it may be included in small amounts. More specifically, N may be included in an amount of 0.0001 to 0.0030 weight%.

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

[0065] Sn and Sb

[0066] Tin (Sn) and antimony (Sb) are elements that improve the texture and may be added for further improvement of magnetism. More specifically, it may contain 0.005 to 0.200 wt% of Sn or 0.005 to 0.200 wt% of Sb.

[0067] Bi, Pb, Ge, and As

[0068] When bismuth (Bi), lead (Pb), germanium (Ge), and arsenic (As) are added, they further improve magnetic flux density. If they are added appropriately, the aforementioned effects can be additionally obtained; however, if they are included in excessive amounts, a large amount of segregation occurs, which inhibits grain growth and may result in inferior magnetic flux density and iron loss. More specifically, one or more of Bi, Pb, Ge, and As may be included in an amount of 0.200 wt% or less, either individually or in their total amount. More specifically, one or more of Bi, Pb, Ge, and As may be included in an amount of 0.0001 to 0.200 wt%, either individually or in their total amount. More specifically, one or more of Bi, Pb, Ge, and As may be included in an amount of 0.001 to 0.100 wt%, either individually or in their total amount.

[0069]

[0070] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

[0071] Cu: 0.005 to 0.200 wt%

[0072] 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 harmful effect on magnetism. More specifically, it may contain 0.01 to 0.10 weight% of Cu.

[0073] Cr: 0.01 to 0.50 wt%

[0074] Chromium (Cr) plays a role in improving iron loss by increasing resistivity. If too little Cr is added, the effect of increasing resistivity may not be sufficient. If too much Cr is included, magnetic flux density may decrease. More specifically, 0.050 to 0.20 weight% of Cr may be included.

[0075] Ni: 0.05 wt% or less

[0076] 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 harmful effect on magnetism. More specifically, it may contain 0.001 to 0.03 weight% of Ni.

[0077] Zn: 0.01 wt% or less

[0078] If the content of zinc (Zn) is excessive, it can act as an impurity and impair magnetism. Therefore, Zn may be added within the aforementioned range. More specifically, Zn may be included in an amount of 0.001 to 0.005 weight%.

[0079] Co: 0.05 wt% or less

[0080] Cobalt (Co) does not form fine precipitates that reduce the magnetism of the steel sheet, but it increases high-temperature strength, which can cause the coil shape to be defective after hot rolling. More specifically, Co may be included in an amount of 0.001 to 0.02 weight%.

[0081]

[0082] A non-oriented electrical steel sheet according to one embodiment of the present invention may further include one or more of Mo: 0.03 wt% or less, B: 0.0050 wt% or less, V: 0.0050 wt% or less, Ca: 0.0050 wt% or less, Nb: 0.0050 wt% or less, Zr: 0.005 wt% or less, Te: 0.01 wt% or less, and Mg: 0.0050 wt% or less.

[0083] Mo: 0.030 wt% or less

[0084] If molybdenum (Mo) is added in excess, it may suppress the segregation of segregated elements, thereby reducing the texture improvement effect. Therefore, Mo may be included in an amount of 0.03 weight% or less. The lower limit is not specifically limited, but since it plays a role in improving the texture by segregating at the surface and grain boundaries, it may be included in an amount of 0.001 weight% or more. More specifically, Mo may be included in an amount of 0.001 to 0.010 weight%. Even more specifically, Mo may be included in an amount of 0.005 to 0.010 weight%.

[0085] B: 0.0050 wt% or less

[0086] If an excessive amount of boron (B) is added, it may cause deterioration of magnetic properties through the formation of inclusions within the steel. Therefore, B may be included in an amount of 0.005 weight% or less. The lower limit is not specifically limited, but it may be 0.0001 weight% due to steelmaking costs. More specifically, B may be included in an amount of 0.0001 to 0.0030 weight%.

[0087] V: 0.0050 wt% or less

[0088] Vanadium (V) has a very strong tendency to form precipitates in steel and degrades iron loss by forming fine carbides or nitrides inside the base material, thereby inhibiting grain growth and domain wall movement. Therefore, the V content may be 0.0050 wt% or less. The lower limit is not specifically limited, but it may be 0.0003 wt% due to steelmaking costs. That is, V may be included in 0.0003 to 0.0050 wt%. More specifically, V may be included in 0.0003 to 0.0030 wt%.

[0089] Ca: 0.0050 wt% or less

[0090] Calcium (Ca) has a very strong tendency to form precipitates within the steel and degrades iron loss by forming fine sulfides inside the base material, thereby inhibiting grain growth and domain wall movement.

[0091] Nb: 0.0050 wt% or less

[0092] Niobium (Nb) has a very strong tendency to form precipitates in steel and degrades iron loss by forming fine carbides or nitrides within the base material, thereby inhibiting grain growth and domain wall movement. Therefore, the Nb content may be 0.0050 wt% or less. The lower limit is not specifically limited, but it may be 0.0003 wt% due to steelmaking costs. That is, it may contain 0.0003 to 0.0050 wt% of Nb. More specifically, it may contain 0.0003 to 0.0030 wt% of Nb.

[0093] Zr: 0.0050 wt% or less

[0094] If an excessive amount of zirconium (Zr) is added, it may cause deterioration of magnetic properties through the formation of inclusions within the steel. Therefore, Zr may be included in an amount of 0.005 weight% or less. The lower limit is not specifically limited, but it may be set to 0.0001 weight% due to steelmaking costs. That is, Zr may be included in an amount of 0.0001 to 0.0050 weight%. More specifically, it may be included in an amount of 0.0005 to 0.0030 weight%.

[0095] Te: 0.0100 wt% or less

[0096] Tellurium (Te) can be added to prevent the oxide layer, which is fractured during rolling, from being pressed into the base material and to detach it, as it diffuses into the oxide layer on the surface of the hot-rolled coil, increases the coefficient of friction between the oxide layer and the rolling work roll, and increases hardness by concentrating beneath the oxide layer. If the amount of Te added is too small, the effect may be negligible. If too much Te is added, the oxide layer detaches easily, causing the base material to come into direct contact with the work roll, which reduces the above effect, and excessive deformation bands may be generated within the steel sheet during cold rolling, leading to the development of a {111} / ND texture that is unfavorable to magnetism. More specifically, it may contain 0.0001 to 0.007 weight% of tellurium.

[0097] Mg: 0.0050 wt% or less

[0098] Magnesium (Mg) is an element that primarily combines with S to form sulfides and can affect the surface oxide layer of the base iron. Therefore, Mg may be included in an amount of 0.0050 wt% or less. The lower limit is not specifically limited, but it may be 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%.

[0099]

[0100] The remainder comprises Fe and unavoidable impurities. The unavoidable impurities are those introduced during the steelmaking stage and the manufacturing process of non-oriented electrical steel sheets; as this is widely known in the field, a detailed description is 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. If additional elements are included, they replace the remainder, Fe.

[0101]

[0102] A non-oriented electrical steel sheet according to one embodiment of the present invention satisfies the following Equation 1.

[0103] [Equation 1]

[0104] -1.2≤VA+VB+VC-VD≤3.0

[0105] (In Equation 1, VA, VB, VC, and VD represent the area fraction (%) of crystal grains with a diameter of 2 μm or more having orientations within 15° from the (001)

[0110] , (110)

[0001] , (100)

[0001] , and (111)[1-10] orientations, respectively.)

[0106] VA+VB+VC-VD of Equation 1 affects the iron loss and magnetism identified during the process of the present invention. Typically, since the (001)

[0110] , (110)

[0001] , and (100)

[0001] orientations are orientations that are easy to magnetize, a large area fraction of crystal grains having these orientations is advantageous for low iron loss and high magnetic flux density. However, if the fractions of these orientations are excessively high, a problem arises in which the difference in iron loss and magnetic flux density between the rolling direction and the width direction of the material becomes large. If the value of Equation 1 is too small, a problem of high iron loss and low magnetic flux density may occur. Conversely, if the value of Equation 1 is too large, anisotropy of iron loss and magnetic flux density may become a problem. More specifically, the value of Equation 1 can be -1.0 to 3.0. The value of Equation 1 can be measured from a cross-section including the thickness direction of the steel plate. Specifically, it can be measured from the TD plane. The cross-section of the steel plate can be observed using EBSD or the like, and crystal grains with a diameter of 2 μm or more that have an orientation within 15° from each orientation can be identified and the area fraction of the corresponding crystal grains can be calculated to obtain the value. The grain diameter can be determined by assuming a virtual circle with the same area as the grain and using the diameter of that circle. Since the degree to which the grain contributes to iron loss and magnetism is not significant when the grain diameter is too small, the value of Equation 1 can be obtained only for crystal grains of 2 μm or more.

[0107]

[0108] A non-oriented electrical steel sheet according to one embodiment of the present invention can satisfy the following conditions for ratios of hysteresis loss, eddy current loss, and abnormal eddy current loss of W10 / 100, W10 / 400, and W10 / 1000.

[0109] The iron loss ratio of W10 / 100 is hysteresis loss: 60 to 80%, eddy current loss: 5 to 15%, abnormal eddy current loss: 10 to 30%

[0110] The iron loss ratio of W10 / 400 is hysteresis loss: 35 to 65%, eddy current loss: 15 to 30%, abnormal eddy current loss: 15 to 35%

[0111] The iron loss ratio of W10 / 1000 is hysteresis loss: 30 to 50%, eddy current loss: 30 to 50%, abnormal eddy current loss: 20 to 40%.

[0112] W 10 / 100 is the iron loss when a magnetic flux density of 1.0T is induced at a frequency of 100Hz.

[0113] W 10 / 400 is the iron loss when a magnetic flux density of 1.0T is induced at a frequency of 400Hz.

[0114] W 10 / 1000 is the iron loss when a magnetic flux density of 1.0T is induced at a frequency of 1000Hz.

[0115] Hysteresis loss, eddy current loss, and abnormal eddy current loss can be measured by the following method known as the 'KJ Overshott best fit model'.

[0116] It is known that iron loss typically follows the relationship in Equation 2 below based on empirical formulas.

[0117] [Equation 2]

[0118] W t = W h + W e + W a = C × f + B2 × f 2 + B1× f 3 / 2

[0119] W t: Total iron loss measured under a saturation magnetic flux density (Bmax) of 1T

[0120] f: Frequency, measured at 10 to 1000 Hz in the present invention

[0121] W h : Hysteresis loss, corresponding to C × f, where C is the hysteresis loss coefficient

[0122] W e : Eddy current loss, B2× f 2 Corresponds to, B2 is the eddy current loss coefficient

[0123] W a : Ideal eddy current loss, B1× f 3 / 2 , B1 is the ideal eddy current loss coefficient

[0124] At this time W t / f = y, f 1 / 2 If we substitute =x, Equation 2 is transformed into Equation 3 below.

[0125] [Equation 3]

[0126] y = C + B1x + B2x 2

[0127] Ultimately, the values ​​of C, B1, and B2 in Equation 2 can be calculated using the least squares method based on the total iron loss values ​​measured under the condition of a saturation flux density (Bmax) of 1T at various frequencies. In this case, C × f and B2 × f 2 , B1× f 3 / 2 Each corresponds to hysteresis loss, eddy current loss, and abnormal eddy current loss at the corresponding frequency, and based on this, the iron loss ratio can be calculated.

[0128]

[0129] A hot-rolled steel sheet for non-oriented electrical steel according to one embodiment of the present invention may have a resistivity (ρ) of 40 μΩcm or more at 25°C. High-frequency iron loss can be improved as the resistivity increases. More specifically, the resistivity (ρ) at 25°C may be 65 to 85 μΩcm.

[0130]

[0131] A 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 an iron loss (W 10 / 400 ) is 16.0 W / Kg or less, and magnetic flux density (B 50 ) can be 1.60T or more.

[0132] B 50 represents the magnetic flux density induced in a magnetic field of 5000 A / m.

[0133] In one embodiment of the present invention, B 50 and W 10 / 400 is represented by averaging the values ​​measured in the rolling direction (RD direction) and the rolling perpendicular direction (TD direction). More specifically, the non-oriented electrical steel sheet according to one embodiment of the present invention has iron loss (W 10 / 400 ) is 9.0 to 15.8 W / Kg, and magnetic flux density (B 50 ) can be 1.62T to 1.75T.

[0134]

[0135] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention comprises: a step of manufacturing a hot-rolled steel sheet by hot-rolling a slab; a step of manufacturing a cold-rolled sheet by cold-rolling the hot-rolled steel sheet; and a cold-rolled sheet annealing step of annealing the cold-rolled sheet.

[0136] Below, each step is explained in detail.

[0137] First, the slab is hot-rolled.

[0138] As the alloy composition of the slab has been explained in the aforementioned section on the alloy composition of hot-rolled steel sheets for non-oriented electrical steel sheets, a redundant explanation is omitted. Since the alloy composition does not substantially change during the manufacturing process of electrical steel sheets, the alloy composition of electrical steel sheets, slabs, and hot-rolled steel sheets is substantially the same.

[0139] Specifically, the slab contains Si: 1.5 to 5.0%, Al: 0.2 to 2.5%, Mn: 0.5 to 2.0% by weight, and the remainder is Fe and unavoidable impurities.

[0140] As other additional elements have been explained in the section on the alloy composition of hot-rolled steel sheets for non-oriented electrical steel sheets, redundant explanations are omitted.

[0141] The slab can be heated before hot rolling. The heating temperature of the slab is not limited, but the slab can be heated to 1200°C or lower. If the heating temperature of the slab is too high, precipitates such as AlN and MnS present in the slab may be re-dissolved and then finely precipitated during hot rolling and annealing, which can inhibit grain growth and reduce magnetism.

[0142] Next, the slab is hot-rolled to produce a hot-rolled plate.

[0143] The rough rolling stage is a stage in which a slab is rolled and manufactured immediately. Rough rolling and finishing rolling can be distinguished by the thickness after rolling. Typically, the stage of rolling a slab to a thickness of 30 to 50 mm is classified as rough rolling, and the subsequent stage as finishing rolling.

[0144]

[0145] In one embodiment of the present invention, the number of passes refers to the number of times a steel plate passes through a rolling roll. For example, the finishing rolling step may include 3 to 8 rolling passes. If the finishing rolling step includes n rolling passes, the third-to-last pass refers to the (n-2)th pass, and the last pass refers to the nth pass.

[0146] The reduction ratio refers to the ratio obtained by dividing the amount of thickness reduction as the material passes through the rolling roll by the thickness before passing through the rolling roll. If the thickness of the material before passing through the n-2nd rolling roll is 5 mm and the thickness after passing through the n-2nd rolling roll is 3 mm, then the reduction ratio of the n-2nd pass is (5-3) / 5 x 100% = 40%.

[0147] The steps for manufacturing hot-rolled steel sheets include a rough rolling step and a finishing rolling step, and the finishing rolling step includes three or more rolling passes, and the reduction rates for the last three passes of the finishing rolling step, namely the n-2nd, n-1st, and nth passes, are as follows.

[0148] 21% ≤ n-2th reduction rate ≤ 46%, more specifically 24 to 45%.

[0149] 18% ≤ n-1th reduction rate ≤ 39%, more specifically 19 to 38%.

[0150] 7% ≤ nth reduction rate ≤ 25%, more specifically, it can be 8 to 24%.

[0151] By increasing the reduction ratio at the end of the finishing rolling process, the development of the recrystallized structure of the hot-rolled material is influenced, thereby providing a hot-rolled material for electrical steel sheets with excellent room-temperature shock absorption energy values. In addition, the material with the increased reduction ratio at the end of the finishing rolling process influences the orientational dislocation distribution within the material, which in turn influences the formation of the texture in subsequent processes, resulting in the satisfaction of Equation 1.

[0152]

[0153] If the reduction rate per of the last three passes of the finishing rolling stage—namely, the nth, n-1st, and n-2nd passes—is less than the previous standard, it is difficult to sufficiently obtain the aforementioned effect, and the microstructure is not properly formed, which may result in reduced magnetism.

[0154] If the reduction rate for the last three passes of the finishing rolling stage—namely, the nth, n-1th, and n-2nd passes—exceeds the previous criteria, control during rolling becomes extremely difficult, and problems with material shape defects may occur.

[0155] After hot rolling, the thickness of the hot-rolled plate may be 1.0 to 4.5 mm. In one embodiment of the present invention, a step of pre-cold rolling before cold rolling may be additionally included, so that a non-oriented electrical steel sheet of appropriate thickness can be manufactured even if the thickness of the hot-rolled plate is relatively thick. More specifically, the thickness of the hot-rolled plate may be 1.5 to 3.5 mm.

[0156] The step of manufacturing hot-rolled plates can be finish-rolled at a temperature of 850°C or higher.

[0157] If the finishing rolling temperature is too low during hot rolling, the rolling load increases, leading to reduced hot rolling workability. Furthermore, a significant amount of deformation remains in the hot-rolled steel sheet, which causes an increase in the rolling load during the subsequent pre-cold rolling process. In addition, from the deformation during intermediate annealing <111> / ND Recrystallization of the grains is promoted, resulting in lower magnetic flux density. Therefore, the hot rolling finish rolling temperature should be as high as possible, and more specifically, it is desirable to perform finish rolling at a temperature of 860 to 1000°C. The hot-rolled sheet can be coiled at a temperature of 550°C or higher.

[0158] After hot rolling, the hot-rolled steel sheet contains a microstructure in which the proportion of regions with a Grain Orientation Spread value of 0.8 or less, analyzed by EBSD, is 15% or more, and the notched room-temperature impact absorption energy value is 50 J / cm² 2 It could be more than that.

[0159] It includes a microstructure in which the proportion of regions with a Grain Orientation Spread value of 0.8 or less analyzed by EBSD is 15% or more, and the notched room temperature shock absorption energy value is 50 J / cm² 2"Above" signifies that the recrystallization and recovery of the hot-rolled material have progressed sufficiently. This microstructure influences the texture of the final non-oriented electrical steel sheet and improves the texture to enhance both low-frequency and high-frequency iron losses. More specifically, within the region where the Grain Orientation Spread value analyzed by EBSD is 2.0 or less, the proportion of the area with a value of 0.8 or less is 15 to 65%, and the notched room-temperature shock absorption energy value is 52 to 220 J / cm² 2 It could be.

[0160] Grain Orientation Spread (GOS), analyzed by EBSD, is defined as the average value (°, degree) of the misorientation calculated from the mean orientation of the corresponding grain at every location within the grain, and is described in detail in 'Field, DP, et al. "The role of annealing twins during recrystallization of Cu." Acta materialia 55.12 (2007): 4233-4241." In this invention, analysis was performed only when GOS ≤ 2° and grain ≥ 10 μm or greater, because the reliability of GOS calculation decreases when grain < 10 μm.

[0161] Grain Orientation Spread (GOS), analyzed by EBSD, is defined as the average value (°, degree) of the misorientation calculated from the mean orientation of the corresponding grain at every location within the grain, and is described in detail in 'Field, DP, et al. "The role of annealing twins during recrystallization of Cu." Acta materialia 55.12 (2007): 4233-4241." In this invention, analysis was performed only when GOS ≤ 2° and grain ≥ 10 μm or greater, because the reliability of GOS calculation decreases when grain < 10 μm.

[0162] The value of the impact absorption energy at room temperature without notch can be measured using ASTM E23-7 Unnotched Charpy Impact Test Specimen.

[0163] After manufacturing hot-rolled steel sheets, annealing of the hot-rolled sheets may be performed before cold rolling. During the annealing of the hot-rolled sheets, the cracking temperature may be 850 to 1100°C. If the annealing temperature is too low, a recrystallization structure may not form or may grow finely, resulting in a small increase in magnetic flux density; if the annealing temperature is too high, magnetic properties may actually deteriorate, and rolling workability may be poor due to deformation of the sheet shape. More specifically, the temperature range may be 830 to 1170°C. The cracking time may be 15 to 180 seconds. The annealing of the hot-rolled sheets may be omitted if necessary.

[0164] Returning to the explanation of the manufacturing method for non-oriented electrical steel sheets, a cold-rolled sheet is produced by cold-rolling a hot-rolled steel sheet. At this time, cold rolling can be performed with a reduction rate of 30 to 95%. If the reduction rate is too low, the deformation energy accumulated in the rolled steel sheet is small, making it difficult to recrystallize during the subsequent annealing process. As a result, the rolled structure remains, which may cause problems in improving magnetic flux density and iron loss. Conversely, if the reduction rate is too high, during the subsequent annealing process <111> / ND The recrystallization of the grains is promoted and the grains become finer, which may cause problems such as reduced magnetic flux density and increased iron loss. More specifically, the reduction ratio may be 40 to 70%. The thickness may be 0.1 mm to 0.3 mm. More specifically, it may be 0.15 to 0.25 mm. For the cold rolling step, 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 may be used.

[0165] Cold rolling can be performed as a single step if necessary, or as two steps with intermediate annealing in between. In either case, the final reduction rate must be in the range of 30 to 80% to ensure excellent magnetism through appropriate texture control.

[0166] Next, the cold-rolled steel sheet is annealed. In the process of annealing the cold-rolled sheet, there are generally no significant restrictions on the annealing temperature as long as it is a temperature typically applied to non-oriented electrical steel. The iron loss of non-oriented electrical steel is closely related to the grain size. The iron loss of non-oriented electrical steel can be classified into hysteresis loss and eddy current loss; hysteresis loss decreases as the grain size increases, while conversely, eddy current loss increases as the grain size increases. Consequently, 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 can secure the optimal grain size, and the annealing temperature can be between 850 and 1100°C. If the annealing temperature is too low, the grains become too fine, increasing hysteresis loss; if it is too high, the grains become too coarse, increasing eddy current loss and potentially resulting in inferior iron loss. More specifically, annealing can be performed at 900 to 1050°C.

[0167] After the annealing step of the cold-rolled sheet, a step of forming an insulating film on the steel sheet may be further included to ensure insulation and corrosion resistance. Since the insulating film is widely known, a detailed description is omitted.

[0168]

[0169] The present invention will be explained in more detail below through examples. However, these examples are merely for illustrating the invention and the invention is not limited thereto.

[0170]

[0171] Examples

[0172] A slab was manufactured with the composition shown in Table 1 below. The remainder was Fe and unavoidable impurities. The slab was heated to 1180°C and hot-rolled to a thickness of 2.1 mm. At this time, finishing rolling was performed with 7 passes, and the reduction rates for the 5th, 6th, and 7th passes were adjusted as shown in Table 1 below. The finishing rolling temperature was set to 910°C, and the slab was coiled at 620°C to produce a hot-rolled steel sheet with a thickness of 2.1 mm.

[0173] The proportion of hot-rolled steel sheets with a Grain Orientation Spread value of 0.8 or less within the region of EBSD analysis of Grain Orientation Spread values ​​of 2.0 or less was measured by the following method and summarized in Table 1. Grain Orientation Spread (GOS) analyzed by EBSD is described in detail in 'Field, DP, et al. "The role of annealing twins during recrystallization of Cu." Acta materialia 55.12 (2007): 4233-4241." GOS is determined by calculating the misorientation from the average orientation of the corresponding grain at all locations within the grain and determining the average value (°, degree). In this invention, analysis was performed only when GOS ≤ 2° and grain ≥ 10 μm or more, because the reliability of GOS calculation decreases when the grain < 10 μm.

[0174] The values ​​of the impact absorption energy at room temperature without notch were measured using ASTM E23-7 Unnotched Charpy Impact Test Specimen and summarized in Table 1.

[0175] The manufactured hot-rolled steel sheet was annealed at 1000°C for 50 seconds. Then, the annealed hot-rolled sheet was pickled, cold-rolled to a thickness of 0.2 mm, and then finally annealed at 1000°C for 50 seconds.

[0176] Hysteresis loss, eddy current loss, and abnormal eddy current loss were measured by the following methods.

[0177] Hysteresis loss, eddy current loss, and abnormal eddy current loss can be measured by the following Equation 2, known as the 'best fit model of KJ Overshott'.

[0178] [Equation 2]

[0179] Wt = Wh + We + Wa = C × f + B2 × f 2 + B1× f 3 / 2

[0180] Wt: Total iron loss measured under a saturation magnetic flux density (Bmax) of 1T

[0181] f: Frequency, measured at 10 to 1000 Hz in the present invention

[0182] Wh: Hysteresis loss, corresponding to C × f, where C is the hysteresis loss coefficient

[0183] We : Eddy current loss, B2×f 2 Corresponds to, B2 is the eddy current loss coefficient

[0184] Wa : Ideal eddy current loss, B1×f 3 / 2 , B1 is the ideal eddy current loss coefficient

[0185] In this case, Wt / f = y, f 1 / 2 If we substitute =x, Equation 2 is transformed into Equation 3 below.

[0186] [Equation 3]

[0187] y = C + B1x + B2x 2

[0188] Ultimately, after calculating the coefficient values ​​C, B1, and B2 in Equation 2 using the least squares method based on the total iron loss values ​​measured under the condition of a saturation flux density (Bmax) of 1T at various frequencies, C × f and B2 × f 2 , B1× f 3 / 2 Each corresponds to hysteresis loss, eddy current loss, and abnormal eddy current loss at the corresponding frequency, and based on this, the iron loss ratio can be calculated.

[0189] Composition [wt.%] Hot-rolled finish rolling reduction ratio [%] Hot-rolled material properties SiAlMn5 pass6 pass7 pass GOS ≤0.8 / GOS ≤2.0 ratio [%] Non-notched room temperature impact energy [J / cm 2 Invention Example 14.31.11.733291840131 Invention Example 21.70.90.842362444157 Invention Example 33.41.90.933291142130 Invention Example 43.81.11.734281245213 Invention Example 54.80.41.929281732190 Invention Example 61.90.80.82923141789 Invention Example 71.80.5 0.930261732174 Invention Example 81.90.71.040361347205 Invention Example 94.20.91.943352015173 Invention Example 101.90.61.52319815214 Invention Example 114.81.90.93026106399 Invention Example 123.70.91.63935223752 Invention Example 134.11.00.82423830 87 Invention Example 143.71.81.53029181557 Invention Example 151.70.41.930291920110 Invention Example 163.21.61.630281028190 Invention Example 174.30.81.845382440147 Invention Example 184.11.31.829231619152 Invention Example 192.41.70.92421926172 Invention Example 2 02.40.71.941372557151 Comparative Example 13.41.90.92035201445 Comparative Example 21.90.71.0191981349 Comparative Example 34.30.81.8241781447 Comparative Example 42.40.71.93016181240 Comparative Example 53.81.11.7393561143 Comparative Example 63.21.61.6242361448

[0190] VA+VB+VC-VD [%]W10 / 100W10 / 400W10 / 1000 Hysteresis Loss Ratio [%] Eddy Current Loss Ratio [%] Abnormal Eddy Current Loss Ratio [%] Hysteresis Loss Ratio [%] Eddy Current Loss Ratio [%] Abnormal Eddy Current Loss Ratio [%] Hysteresis Loss Ratio [%] Eddy Current Loss Ratio [%] Abnormal Eddy Current Loss Ratio [%] Invention Example 1 1.869 1318 3730 334 135 24 Invention Example 2 0.964 630 532 225 304 8 22 Invention Example 3 2.265 142 151 1930 40 30 30 Invention Example 4 2.877 716 4916 353 33 5 32 Invention Example 5 0.967 62 761 201 934 39 27 Invention Example 6 1.864 152 150 30 2030 50 20 Invention Example 7 0.779 111 0532621463321 Invention Example 82.677518522919314524 Invention Example 92.568527363034324226 Invention Example 10-0.4791011632017323335 Invention Example 111.161930542620393031 Invention Example 121.870723501634383923 Invention Example 130.8631225511633314425 Honorary 142.4681517541927403921 Invention Example 151.776717462133323830 Invention Example 162.0661420541828393229 Invention Example 172.2651520422830423127 Invention Example 180.0701515492031383923 Invention Example 193.075619532918353431 Invention Example 202.96312 25622216374023Comparative Example 13.1701614601426512821Comparative Example 2-1.3791110602614302941Comparative Example 3-1.478418661816295021Comparative Example 4-1.3591526503119412930Comparative Example 5-1.562731481636315019Comparative Example 63.278139342046305119

[0191] As shown in Tables 1 and 2, when the steel composition is appropriately controlled and the reduction rate in the n-2nd pass to the last pass of finishing rolling during hot rolling is appropriately controlled, the ratio of the Grain Orientation Spread value of 0.8 or less in the region of 2.0 or less analyzed by EBSD of the hot-rolled steel sheet and the notched room temperature shock absorption energy value are increased, and an appropriate microstructure is formed after annealing of the cold-rolled sheet, and as a result, the ratio of hysteresis loss, eddy current loss, and abnormal eddy current loss within the iron loss is appropriately controlled, and it can be confirmed that both low-frequency and high-frequency iron losses are excellent.

[0192] Meanwhile, if the reduction ratio of finishing rolling during hot rolling is not properly controlled, the microstructure is not properly formed after annealing of the hot-rolled steel sheet and cold-rolled sheet, and it can be confirmed that the ratio of hysteresis loss, eddy current loss, and abnormal eddy current loss of low-frequency and high-frequency iron loss deviates from the appropriate level.

[0193]

[0194] The present invention is not limited to the embodiments described above but can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without altering the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. A non-oriented electrical steel sheet comprising, in weight%, Si: 1.5 to 5.0%, Al: 0.2 to 2.5%, Mn: 0.5 to 2.0%, the remainder being Fe and unavoidable impurities, and satisfying Formula 1 below. [Equation 1] -1.2≤VA+VB+VC-VD≤3.0 (In Equation 1, VA, VB, VC, and VD represent the area fraction (%) of crystal grains with a diameter of 2 μm or more having orientations within 15° from the (001)[110], (110)[001], (100)[001], and (111)[1-10] orientations, respectively.) 2. In Paragraph 1, Non-oriented electrical steel sheets with a ratio of hysteresis loss, eddy current loss, and abnormal eddy current loss of W10 / 100, W10 / 400, and W10 / 1000 satisfying the following conditions. The iron loss ratio of W10 / 100 is hysteresis loss: 60 to 80%, eddy current loss: 5 to 15%, abnormal eddy current loss: 10 to 30% The iron loss ratio of W10 / 400 is hysteresis loss: 35 to 65%, eddy current loss: 15 to 30%, abnormal eddy current loss: 15 to 35% The iron loss ratio of W10 / 1000 is hysteresis loss: 30 to 50%, eddy current loss: 30 to 50%, abnormal eddy current loss: 20 to 40%.

3. In Paragraph 1, A non-oriented electrical steel sheet further comprising one or more of P: 0.1 wt% or less, C: 0.005 wt% or less, S: 0.005 wt% or less, Ti: 0.005 wt% or less, and N: 0.005 wt% or less.

4. In Paragraph 1, A non-oriented electrical steel sheet further comprising 0.005 to 0.200 weight% of one or more of Sn, Sb, Bi, Pb, Ge, and As, either individually or in their combined amount.

5. In Paragraph 1, A non-oriented electrical steel sheet further comprising one or more of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

6. In Paragraph 1, A non-oriented electrical steel sheet further comprising one or more of Mo: 0.03 wt% or less, B: 0.0050 wt% or less, V: 0.0050 wt% or less, Ca: 0.0050 wt% or less, Nb: 0.0050 wt% or less, Zr: 0.005 wt% or less, Te: 0.01 wt% or less, and Mg: 0.0050 wt% or less.

7. In weight%, it comprises Si: 1.5 to 5.0%, Al: 0.2 to 2.5%, Mn: 0.5 to 2.0%, and the remainder comprises Fe and unavoidable impurities, It includes a microstructure in which the proportion of regions with a Grain Orientation Spread value of 0.8 or less analyzed by EBSD is 15% or more, and the notched room temperature shock absorption energy value is 50 J / cm² 2 Hot-rolled steel sheet for manufacturing non-oriented electrical steel sheets.

8. A step of manufacturing a hot-rolled steel sheet by hot-rolling a slab containing, by weight%, Si: 1.5 to 5.0%, Al: 0.2 to 2.5%, Mn: 0.5 to 2.0%, and the remainder being Fe and unavoidable impurities; A step of manufacturing a cold-rolled plate by cold-rolling the above hot-rolled steel plate and A cold-rolled plate annealing step for annealing the above cold-rolled plate; comprising, The step of manufacturing the above hot-rolled steel sheet includes a rough rolling step and a finish rolling step, and The above finishing rolling step includes three or more rolling passes, and A method for manufacturing non-oriented electrical steel sheets where the last pass of the above-mentioned rolling step is called the n-th pass, and the reduction rates of the n-2nd, n-1st, and n-th passes are each as follows. 21% ≤ n-2th reduction rate ≤ 46% 18% ≤ n-1th reduction rate ≤ 39% 7% ≤ nth reduction rate ≤ 25% 9. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further comprises one or more of P: 0.1 wt% or less, C: 0.005 wt% or less, S: 0.005 wt% or less, Ti: 0.005 wt% or less, and N: 0.005 wt% or less.

10. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further comprises 0.005 to 0.200 weight% of one or more of Sn, Sb, Bi, Pb, Ge, and As, respectively or in their combined amount.

11. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further comprises one or more of Cu: 0.005 to 0.2 wt%, Cr: 0.01 to 0.5 wt%, Ni: 0.05 wt% or less, Zn: 0.01 wt% or less, and Co: 0.05 wt% or less.

12. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further comprises one or more of Mo: 0.03 wt% or less, B: 0.0050 wt% or less, V: 0.0050 wt% or less, Ca: 0.0050 wt% or less, Nb: 0.0050 wt% or less, Zr: 0.005 wt% or less, Te: 0.01 wt% or less, and Mg: 0.0050 wt% or less.

13. In Paragraph 8, The above hot-rolled steel sheet contains a microstructure in which the proportion of regions with a Grain Orientation Spread value of 0.8 or less, analyzed by EBSD, is 15% or more, and the notched room temperature shock absorption energy value is 50 J / cm² 2 Method for manufacturing non-oriented electrical steel sheets.