Non-oriented electrical steel sheet and method for manufacturing non-oriented electrical steel sheet

Abstract

The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the non-oriented electrical steel sheet. According to an embodiment of the present invention, there may be provided a non-oriented electrical steel sheet and a method for manufacturing the non-oriented electrical steel sheet, in which, by including a resistivity element in an alloy component and controlling same, the non-oriented electrical steel sheet exhibits excellent rollability and low iron loss.

Description

Non-oriented electrical steel sheet and method for manufacturing non-oriented electrical steel sheet

[0001] The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing a non-oriented electrical steel sheet.

[0002] In line with recent global policies to reduce carbon dioxide emissions to combat global warming, conventional internal combustion engine vehicles are rapidly being replaced by eco-friendly vehicles such as hybrid, electric, and hydrogen-powered vehicles. Eco-friendly vehicles utilize electric motors to generate the necessary driving force and significantly reduce harmful exhaust gas emissions, thereby minimizing environmental pollution.

[0003] As interest in and demand for eco-friendly vehicles grows, so does the demand for electric motors, which power these vehicles. Electric motors use electricity to generate the power needed for vehicles. Energy efficiency, which allows them to operate for longer periods of time using the same amount of energy, is a crucial technological element.

[0004] Non-oriented electrical steel sheets used in eco-friendly vehicles are typically manufactured by laminating multiple cold-rolled steel sheets, each 0.30 mm or less thick, by punching them. To improve the magnetic properties of non-oriented electrical steel sheets, core loss must be reduced by reducing the sheet thickness, increasing the resistivity, and / or controlling the content of impurity elements.

[0005] By adding elements such as Si, Al, or Mn, the resistivity can be increased and eddy current loss can be reduced, but as the single addition amount of each element increases, the rollability during cold rolling decreases, which increases the process cost and leads to a decrease in production volume.

[0006] Additionally, as elements and impurities such as Si, Al or Mn increase, precipitates are generated, and brittleness increases due to grain refinement and increased hardness, which increases the risk of fracture during the rolling process.

[0007] Therefore, there is a need to develop a non-oriented electrical steel sheet that exhibits excellent rollability and resistivity, thus exhibiting low iron loss, and a technology for manufacturing the same.

[0008] The purpose of the present invention is to provide a non-oriented electrical steel sheet and a method for manufacturing a non-oriented electrical steel sheet.

[0009] Specifically, the purpose is to provide a non-oriented electrical steel sheet and a method for manufacturing a non-oriented electrical steel sheet that exhibit excellent rollability and low iron loss by controlling alloy components.

[0010] More specifically, the purpose is to provide a non-oriented electrical steel sheet and a method for manufacturing a non-oriented electrical steel sheet that exhibits excellent rollability and resistivity and low iron loss by including a resistivity element in the alloy composition and controlling the resistivity element.

[0011] The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the description below.

[0012] According to one embodiment of the present invention, a non-oriented electrical steel sheet is disclosed, which contains 3.0 wt% or more and 3.7 wt% or less of silicon (Si), 0.8 wt% or more and 1.5 wt% or less of aluminum (Al), 0.2 wt% or more and 0.4 wt% or less of manganese (Mn), 0.003 wt% or less of tin (Sn) (excluding 0 wt%), 0.003 wt% or less of yttrium (Y) (excluding 0 wt%), 0.002 wt% or less of sulfur (S) (excluding 0 wt%), 0.014 wt% or less of phosphorus (P) (excluding 0 wt%), and the remainder iron (Fe) and other unavoidable impurities, and satisfies the following Equations 1 and 2.

[0013] [Formula 1]

[0014] 0 < [Sn] + [Y] ≤ 0.0050

[0015] In Equation 1, [Sn] and [Y] represent the contents of Sn and Y in wt%, respectively.

[0016] [Formula 2]

[0017] 80 ≤ HV - {(100 × ρ) / d} ≤ 140

[0018] In Equation 2, HV is the Vickers hardness, ρ is calculated by Equation 3 below, and d is the grain size (㎛).

[0019] [Formula 3]

[0020] 10.1169 + 11.7499*[Si] + 8.76*[Al] + 6.1985*[Mn] - 10.3715*[S] + 14.3269*[P] + 1317*([Sn]+[Y])

[0021] In Equation 3, [Si], [Al], [Mn], [S], [P], [Sn] and [Y] represent the contents of Si, Al, Mn, S, P, Sn and Y, respectively, in wt%.

[0022] In addition, the following equation 4 can be satisfied.

[0023] [Formula 4]

[0024] 0 < [Si] + [Al] ≤ 4.5

[0025] In Equation 4, [Si] and [Al] represent the contents of Si and Al, respectively, in wt%.

[0026] Additionally, the Vickers hardness may be within the range of 100 HV or more and 190 HV or less.

[0027] Additionally, the resistivity may be greater than 60 μΩ·cm.

[0028] Additionally, the crystal grain size may be within a range of 110 ㎛ or more and 200 ㎛ or less.

[0029] Also, iron loss (W 10 / 400 ) may be less than 14.3 W / kg.

[0030] Additionally, it may further include at least one of carbon (C) 0.002 wt% or less (excluding 0 wt%), nitrogen (N) 0.002 wt% or less (excluding 0 wt%), and titanium (Ti) 0.002 wt% or less (excluding 0 wt%).

[0031] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention includes a step of reheating a slab containing 3.0 wt% or more of silicon (Si) and 3.7 wt% or less, 0.8 wt% or more of aluminum (Al) and 1.5 wt% or less, 0.2 wt% or more of manganese (Mn) and 0.4 wt% or less, 0.003 wt% or less of tin (Sn) (excluding 0 wt%), 0.003 wt% or less of yttrium (Y) (excluding 0 wt%), 0.002 wt% or less of sulfur (S) (excluding 0 wt%), 0.014 wt% or less of phosphorus (P) (excluding 0 wt%), and the remainder iron (Fe) and other unavoidable impurities, and a step of hot rolling, a step of hot rolling annealing, a step of cold rolling, and a step of cold rolling annealing, and a method for manufacturing a non-oriented electrical steel sheet satisfying the following Equations 1 and 2 is disclosed.

[0032] [Formula 1]

[0033] 0 < [Sn] + [Y] ≤ 0.0050

[0034] In Equation 1, [Sn] and [Y] represent the contents of Sn and Y in wt%, respectively.

[0035] [Formula 2]

[0036] 80 ≤ HV - {(100 × ρ) / d} ≤ 140

[0037] In Equation 2, HV is the Vickers hardness, ρ is calculated by Equation 3 below, and d is the grain size (㎛).

[0038] [Formula 3]

[0039] 10.1169 + 11.7499*[Si] + 8.76*[Al] + 6.1985*[Mn] - 10.3715*[S] + 14.3269*[P] + 1317*([Sn]+[Y])

[0040] In Equation 3, [Si], [Al], [Mn], [S], [P], [Sn] and [Y] represent the contents of Si, Al, Mn, S, P, Sn and Y, respectively, in wt%.

[0041] In addition, the following equation 4 can be satisfied.

[0042] [Formula 4]

[0043] 0 < [Si] + [Al] ≤ 4.5

[0044] In Equation 4, [Si] and [Al] represent the contents of Si and Al, respectively, in wt%.

[0045] In addition, the steel sheet manufactured after the above cold rolling annealing step may have a Vickers hardness within a range of 100 HV or more and 190 HV or less.

[0046] In addition, the steel sheet manufactured after the cold rolling annealing step may have a resistivity of 60 μΩ·cm or more.

[0047] In addition, the steel sheet manufactured after the cold rolling annealing step may have a grain size within a range of 110 ㎛ or more and 200 ㎛ or less.

[0048] In addition, the steel sheet manufactured after the above cold rolling annealing step has a core loss (W 10 / 400 ) may be less than 14.3 W / kg.

[0049] Additionally, it may further include at least one of carbon (C) 0.002 wt% or less (excluding 0 wt%), nitrogen (N) 0.002 wt% or less (excluding 0 wt%), and titanium (Ti) 0.002 wt% or less (excluding 0 wt%).

[0050] According to one embodiment of the present invention, a non-oriented electrical steel sheet and a method for manufacturing a non-oriented electrical steel sheet can be provided.

[0051] Specifically, by controlling the alloy composition, a non-oriented electrical steel sheet and a method for manufacturing a non-oriented electrical steel sheet exhibiting excellent rollability and low iron loss can be provided.

[0052] More specifically, by including a resistivity element in the alloy composition and controlling it, a non-oriented electrical steel sheet and a method for manufacturing a non-oriented electrical steel sheet having excellent rollability and resistivity and low iron loss can be provided.

[0053] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

[0054] Hereinafter, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention is not limited or restricted by the following examples.

[0055] Additionally, when a component (or region, layer, portion, etc.) is referred to as being "on," "connected to," or "coupled to" another component, it means that it can be directly placed / connected / coupled to the other component, or that a third component may be placed between them.

[0056] Terms such as "include" or "have" should be understood to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but not to exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0057] In order to clearly explain the present invention, detailed descriptions of parts that are irrelevant to the description or related known technologies that may unnecessarily obscure the gist of the present invention have been omitted.

[0058] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0059] Unless otherwise specified, the notation 'A to B' or 'A to B' for numerical values ​​A and B means 'A or more and B or less'. In such notation, if a unit is attached only to numerical value B, the unit shall also be applied to numerical value A.

[0060] Also, unless otherwise stated, 1 ppm is 0.0001 wt%.

[0061]

[0062] Non-oriented electrical steel sheet

[0063] A non-oriented electrical steel sheet according to one embodiment disclosed in the present specification includes silicon (Si) at 3.0 wt% or more and 3.7 wt% or less, aluminum (Al) at 0.8 wt% or more and 1.5 wt% or less, manganese (Mn) at 0.2 wt% or more and 0.4 wt% or less, tin (Sn) at 0.003 wt% or less (excluding 0 wt%), yttrium (Y) at 0.003 wt% or less (excluding 0 wt%), sulfur (S) at 0.002 wt% or less (excluding 0 wt%), and phosphorus (P) at 0.014 wt% or less (excluding 0 wt%).

[0064] Hereinafter, the role and content of alloy elements included in the steel of the non-oriented electrical steel sheet according to one embodiment disclosed in the present specification will be described in detail.

[0065]

[0066] Silicon (Si)

[0067] Silicon (Si) is a key additive in electrical steel, increasing the steel's resistivity and reducing core loss. However, too little silicon can insufficiently improve core loss. However, excessive silicon can reduce magnetic flux density and, due to increased brittleness, compromise cold-rollability. Therefore, appropriate adjustment of the silicon content is necessary.

[0068] If the silicon content is less than 3.0 wt%, the above-described effect cannot be expected, and if the silicon content exceeds 3.7 wt%, problems such as a decrease in magnetic flux density and an increase in brittleness may occur. Therefore, the non-oriented electrical steel sheet according to one embodiment of the present invention may contain silicon in an amount of 3.0 wt% or more and 3.7 wt% or less.

[0069]

[0070] Aluminum (Al)

[0071] Aluminum (Al), like silicon (Si), increases resistivity and reduces iron loss. It is a key additive in electrical steel, a soft magnetic material. Aluminum can also play a role in reducing magnetic anisotropy, thereby reducing magnetic deviation.

[0072] When the aluminum content is less than 0.8 wt%, the increase in resistivity is insufficient, which can increase iron loss, and nitrides such as AlN can be precipitated by combining with nitrogen. When the aluminum content exceeds 1.5 wt%, excessive nitride precipitation can reduce the magnetic flux density, and cold-rolling properties can be reduced due to increased brittleness. Therefore, it is necessary to appropriately control the aluminum content.

[0073] Accordingly, the non-oriented electrical steel sheet according to one embodiment disclosed in the present specification may contain aluminum in an amount of 0.8 wt% or more and 1.5 wt% or less.

[0074]

[0075] manganese (Mn)

[0076] Manganese (Mn), along with silicon (Si) and aluminum (Al), is an element that improves magnetic properties by increasing resistivity and reducing iron loss.

[0077] When the manganese content is less than 0.2 wt%, sulfur (S) within the steel precipitates as fine MnS, which can hinder the growth of grains beneficial to magnetic properties. When the manganese content exceeds 0.4 wt%, coarse MnS precipitates, which can reduce the magnetic flux density. Therefore, it is necessary to appropriately control the manganese content.

[0078] Accordingly, the steel according to one embodiment disclosed in the present specification may contain manganese in an amount of 0.2 wt% or more and 0.4 wt% or less.

[0079]

[0080] Sn

[0081] Tin (Sn) is an element that increases resistivity and reduces iron loss. Tin is a precipitant that forms precipitates on the surface of steel sheets and can be concentrated in the surface layer of the steel sheet. This concentrated tin suppresses nitrogen adsorption and nitride formation, thereby reducing iron loss. However, if the tin content exceeds 0.003 wt%, fine tin and yttrium precipitates, such as Sn2Y or Sn5Y2, can form, increasing iron loss. Therefore, it is necessary to appropriately control the tin content.

[0082] Accordingly, the non-oriented electrical steel sheet according to one embodiment disclosed in the present specification may contain tin in an amount of more than 0 wt% and less than or equal to 0.003 wt% (more than 0 ppm and less than or equal to 30 ppm).

[0083]

[0084] Yttrium (Y)

[0085] Yttrium (Y) is an element that increases resistivity and reduces iron loss. If the content of yttrium exceeds 0.003 wt%, it can form fine precipitates such as YS, Y2S3, Sn2Y, or Sn5Y2, which hinders domain wall movement and thus increases iron loss. In addition, it can cause problems such as grain refinement and increased hardness, which leads to increased brittleness and reduced rollability.

[0086] Accordingly, the non-oriented electrical steel sheet according to one embodiment disclosed in the present specification may include yttrium (Y) in an amount of more than 0 wt% and less than or equal to 0.003 wt% (more than 0 ppm and less than or equal to 30 ppm).

[0087]

[0088] Yellow (S)

[0089] Sulfur (S) is an impurity element in steel that is inevitably contained during the manufacturing process. When added in large amounts, it can increase iron loss by forming precipitates such as MnS and CuS, and can inhibit grain growth, thereby deteriorating magnetic properties. Therefore, the non-oriented electrical steel sheet according to one embodiment disclosed in the present specification may contain sulfur in an amount of more than 0 wt% and less than 0.002 wt% (more than 0 ppm and less than 20 ppm).

[0090]

[0091] Person (P)

[0092] Phosphorus (P) is an element that improves the grain structure by segregating at grain boundaries, thereby increasing resistivity and reducing iron loss.

[0093] However, when the phosphorus content exceeds 0.014 wt%, excessive grain boundary segregation may be formed, which may inhibit grain growth and cause a decrease in cold rolling properties. Therefore, the non-oriented electrical steel sheet according to one embodiment disclosed herein may contain phosphorus (P) in an amount exceeding 0 wt% and not more than 0.014 wt% (not more than 0 ppm and not more than 140 ppm).

[0094]

[0095] Additionally, according to one embodiment disclosed herein, the steel may further include at least one of carbon (C) 0.002 wt% or less (excluding 0 wt%), nitrogen (N) 0.002 wt% or less (excluding 0 wt%), and titanium (Ti) 0.002 wt% or less (excluding 0 wt%).

[0096]

[0097]

[0098] *Carbon (C)

[0099] Carbon (C) can increase iron loss by combining with titanium (Ti) and niobium (Nb) to form carbides such as TiC and NbC, so a lower carbon content is preferable. If carbon exceeds 0.002 wt%, it can cause magnetic aging, which can deteriorate magnetic properties.

[0100] Therefore, the non-oriented electrical steel sheet according to one embodiment disclosed in the present specification may contain carbon in an amount of 0.002 wt% or less. Preferably, it may contain carbon in an amount of more than 0 wt% and less than 0.002 wt% (more than 0 ppm and less than 20 ppm).

[0101]

[0102] Nitrogen (N)

[0103] Nitrogen (N) combines with aluminum (Al) and titanium (Ti) to form precipitates such as AlN and TiN, which increases iron loss and inhibits grain growth. Therefore, it is desirable to keep nitrogen addition as low as possible.

[0104] Accordingly, the non-oriented electrical steel sheet according to one embodiment disclosed herein may contain nitrogen (N) in an amount of 0.002 wt% or less. Preferably, it may contain nitrogen (N) in an amount of more than 0 wt% and less than 0.002 wt% (more than 0 ppm and less than 20 ppm).

[0105]

[0106] titanium (Ti)

[0107] Titanium (Ti) is an element with a very strong tendency to form precipitates in steel, and combines with carbon (C) or nitrogen (N) to form precipitates such as TiC and TiN, thereby inhibiting grain growth. As more titanium is added, the magnetic properties deteriorate, so it is desirable to add as little titanium as possible. Therefore, the non-oriented electrical steel sheet according to one embodiment disclosed in the present specification may contain titanium (Ti) in an amount of 0.002 wt% or less. Preferably, it may contain more than 0 wt% and 0.002 wt% or less (more than 0 ppm and 20 ppm or less).

[0108]

[0109] In addition to the aforementioned steel components, the remainder may contain iron and unavoidable impurities. Unavoidable impurities are impurities introduced during the steelmaking process and the manufacturing process of non-oriented electrical steel sheets. Since these impurities are widely known in the field, a detailed description will be omitted.

[0110] In one embodiment disclosed herein, 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 invention disclosed herein. When additional elements are included, they may be included to replace the remaining Fe.

[0111]

[0112] A non-oriented electrical steel sheet according to one embodiment disclosed in this specification can satisfy the following equation 1.

[0113] [Formula 1]

[0114] 0 < [Sn] + [Y] ≤ 0.0050

[0115] In Equation 1, [Sn] and [Y] represent the contents of Sn and Y in wt%, respectively.

[0116] For example, Equation 1 controls the content of resistivity elements of a non-oriented electrical steel sheet, and may mean that even if the content of each resistivity element is within the content range disclosed in this specification, the rollability of the non-oriented electrical steel sheet can be appropriately secured by controlling the sum of the contents of [Sn] and [Y] corresponding to the resistivity elements.

[0117] For example, if the value of Equation 1 exceeds 0.0050 wt%, even if a high resistivity can be secured, fine Sn-Y precipitates may be excessively precipitated, which may hinder domain wall movement and cause grain refinement, thereby increasing hardness. Accordingly, if the value of Equation 1 exceeds 0.0050 wt%, the non-oriented electrical steel sheet may fracture during cold rolling. Therefore, the value of Equation 1 may be within a range of more than 0 wt% and less than or equal to 0.0050 wt%.

[0118] A non-oriented electrical steel sheet according to one embodiment disclosed in this specification can satisfy the following equation 2.

[0119] [Formula 2]

[0120] 80 ≤ HV - {(100 × ρ) / d} ≤ 140

[0121] In Equation 2, HV is the Vickers hardness, ρ is calculated by Equation 3 below, and d is the grain size (㎛).

[0122] [Formula 3]

[0123] 10.1169 + 11.7499*[Si] + 8.76*[Al] + 6.1985*[Mn] - 10.3715*[S] + 14.3269*[P] + 1317*([Sn]+[Y])

[0124] In Equation 3, [Si], [Al], [Mn], [S], [P], [Sn] and [Y] represent the contents of Si, Al, Mn, S, P, Sn and Y, respectively, in wt%.

[0125] If Equation 2 is less than 80, the resistivity may be large, making it difficult to secure iron loss. If Equation 2 exceeds 140, the Vickers hardness may be very large, and fracture may occur during cold rolling. Therefore, the value of Equation 2 may be within the range of 80 to 140. Vickers hardness and grain size will be described later.

[0126] A non-oriented electrical steel sheet according to an embodiment disclosed in this specification can satisfy the following equation 4.

[0127] [Formula 4]

[0128] 0 < [Si] + [Al] ≤ 4.5

[0129] In Equation 4, [Si] and [Al] represent the contents of Si and Al, respectively, in wt%.

[0130] Silicon and aluminum are essential elements of the non-oriented electrical steel sheet according to one embodiment disclosed herein, as they increase resistivity and reduce iron loss. However, when the content of Equation 4 exceeds 4.5 wt%, fracture may occur during rolling due to reduced cold-rollability caused by increased brittleness. Therefore, the value of Equation 4 may be within a range of more than 0 wt% and less than or equal to 4.5 wt%.

[0131] The non-oriented electrical steel sheet according to one embodiment disclosed in the present specification may have a Vickers hardness of 190 HV or less. The Vickers hardness is measured according to the method described in the experimental example below, '1. Vickers hardness'. If the Vickers hardness exceeds 190 HV, fracture may occur during a cold rolling process due to excessively high strength or hardness. Therefore, the non-oriented electrical steel sheet according to one embodiment disclosed in the present specification may have a Vickers hardness of 190 HV. In addition, the lower limit of the Vickers hardness is not particularly limited, but the non-oriented electrical steel sheet according to one embodiment disclosed in the present specification may have a Vickers hardness of 100 HV or more.

[0132] The non-oriented electrical steel sheet according to one embodiment disclosed in the present specification may have a resistivity equal to or higher than a certain value. The resistivity may be calculated by the above-described Equation 3. For example, in the case of a non-oriented electrical steel sheet satisfying Equations 1 and 2, the value of Equation 3 may be equal to or higher than 60 μΩ·cm. When the resistivity is high, eddy current loss may be reduced to reduce iron loss, but depending on the alloy component and its content included to increase the resistivity, the magnetic flux density may be reduced or brittleness may be increased. Therefore, the resistivity of the non-oriented electrical steel sheet according to one embodiment disclosed in the present specification or the resistivity calculated by Equation 3 may have a lower limit of about 60 μΩ·cm or more, about 70 μΩ·cm or more, or about 80 μΩ·cm or more, and the upper limit is not particularly limited, but may be equal to or lower than 140 μΩ·cm.

[0133] According to an embodiment of the present invention, a non-oriented electrical steel sheet may have a grain size in a range of 110 ㎛ to 200 ㎛. The grain size is measured according to the method described in '2. Grain size' in the experimental example described below. When the grain size is less than 110 ㎛, grain growth is suppressed, which may increase iron loss, and when the grain size exceeds 200 ㎛, the grains are coarse, which may increase eddy current loss. Therefore, the grain size may be in a range of 110 ㎛ to 200 ㎛.

[0134] In one embodiment disclosed herein, the non-oriented electrical steel sheet has a core loss (W 10 / 400 ) may be a non-oriented electrical steel sheet having a low iron loss characteristic of 14.3 W / kg or less. The iron loss (W 10 / 400 ) is not particularly limited, but in one embodiment disclosed herein, the core loss (W) of the non-oriented electrical steel sheet 10 / 400 ) can be greater than or equal to 11.4 W / kg. Iron loss (W 10 / 400) means the iron loss when a magnetic flux density of 1.0 T is induced at a frequency of 400 Hz, and is measured according to the method described in '4. Iron loss' in the experimental example described below.

[0135] Hereinafter, a method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention will be described in detail.

[0136]

[0137] Method for manufacturing non-oriented electrical steel sheet

[0138] The present invention also relates to a method for manufacturing a non-oriented electrical steel sheet.

[0139] The method for manufacturing a non-oriented electrical steel sheet disclosed in this specification includes a step of reheating a slab containing the above-described alloy component and then hot rolling it, a step of hot rolling annealing it, a step of cold rolling it, and a step of cold rolling annealing it.

[0140] The above slab contains 3.0 wt% or more and 3.7 wt% or less of silicon (Si), 0.8 wt% or more and 1.5 wt% or less of aluminum (Al), 0.2 wt% or more and 0.4 wt% or less of manganese (Mn), 0.003 wt% or less of tin (Sn) (excluding 0 wt%), 0.003 wt% or less of yttrium (Y) (excluding 0 wt%), 0.002 wt% or less of sulfur (S) (excluding 0 wt%), 0.014 wt% or less of phosphorus (P) (excluding 0 wt%), and the remainder iron (Fe) and other unavoidable impurities.

[0141] Additionally, the slab may further include at least one of carbon (C) 0.002 wt% or less (excluding 0 wt%), nitrogen (N) 0.002 wt% or less (excluding 0 wt%), and titanium (Ti) 0.002 wt% or less (excluding 0 wt%).

[0142] Since the content of the alloy components has been previously explained, a duplicate explanation will be omitted. In addition, the content of the alloy components disclosed in the non-oriented electrical steel sheet described above does not substantially change during the manufacturing process, and therefore, the alloy components disclosed in the method for manufacturing the non-oriented electrical steel sheet and the alloy components of the final product, the non-oriented electrical steel sheet, are substantially the same.

[0143] Hereinafter, each step of a method for manufacturing a non-oriented electrical steel sheet according to an embodiment disclosed in this specification will be described in detail.

[0144]

[0145] The hot rolling step may include designing the alloy composition within the above-described alloy composition range to manufacture a slab, which is a semi-finished product, and reheating the slab, followed by hot rolling to manufacture a hot-rolled steel sheet. Furthermore, the slab manufacturing process may be performed using a process known in the relevant technical field, such as a steelmaking process or a casting process.

[0146] Slab reheating may be performed at a temperature of 1000°C or higher and 1250°C or lower. If the reheating temperature is lower than 1000°C, excessive force may be required during hot rolling, which may strain the equipment or make smooth hot rolling difficult. Furthermore, if the reheating temperature exceeds 1250°C, surface oxidation of the steel or slab may occur, resulting in the re-dissolution of precipitates. This re-dissolution of precipitates may inhibit grain growth and increase iron loss during the rolling or annealing steps described below. Therefore, in one embodiment disclosed herein, the reheating temperature may be higher than 1000°C and lower than 1250°C.

[0147] Next, a hot rolling process may be performed to form a hot-rolled steel sheet by hot-rolling the reheated steel. The hot rolling process may include rough rolling and finish rolling. Here, rough rolling may refer to forming the steel into a rolled material with an appropriate shape, thickness, and width, and finish rolling may refer to adjusting the steel to a specified thickness and width and rolling it at a finishing temperature suitable for the intended use to achieve a good surface and shape.

[0148] At this time, the finishing temperature of the hot rolling process may be carried out at a temperature for uniform tissue formation and appropriate strength enhancement, and preferably, the finishing temperature may be 850°C or more and 900°C or less. For example, if the finishing temperature is less than 850°C, rolling may be performed in a two-phase region, which may result in the formation of an uneven tissue, and if the finishing temperature exceeds 900°C, a problem may arise in which the strength or hardness of the steel material is rapidly reduced. Therefore, in one embodiment disclosed in the present specification, the finishing temperature of the hot rolling process may be 850°C or more and 900°C or less.

[0149] Afterwards, a coiling process may be performed to coil the hot-rolled steel sheet formed through the hot rolling process. At this time, the coiling temperature is preferably 550°C or higher and 750°C or lower. If the coiling temperature is lower than 550°C, brittleness increases, which may cause fracture during cold rolling, and the grain size may become too small, preventing sufficient grain growth even after annealing. On the other hand, if the coiling temperature exceeds 750°C, fine precipitates may be generated, which may deteriorate the magnetic properties. Therefore, in one embodiment disclosed in the present specification, the coiling temperature of the hot rolling process may be 550°C or higher and 750°C or lower.

[0150] The thickness of the hot-rolled steel sheet formed through the step of hot-rolling the above steel may be 1.8 mm or more and 3.5 mm or less. For example, if the thickness of the hot-rolled steel sheet is less than 1.8 mm, the thickness obtained after cold rolling is insufficient, which may cause shape defects when applied to the product, and if the thickness of the hot-rolled steel sheet exceeds 3.5 mm, the cold-rolling reduction ratio increases, and the fraction of aggregate structures unfavorable to magnetic properties increases, which may result in inferior magnetic properties. Therefore, in one embodiment disclosed in the present specification, the thickness of the hot-rolled steel sheet formed by performing the reheating, hot rolling, and / or coiling processes may be 1.8 mm or more and 3.5 mm or less.

[0151] The hot-rolling and annealing step may be a step of hot-rolling and annealing the hot-rolled steel sheet to form a hot-rolled and annealed hot-rolled steel sheet.

[0152] The hot-rolling annealing step may be performed at a temperature of 950°C or more and 1100°C or less. For example, if the hot-rolling annealing temperature is lower than 950°C, the grains may not grow sufficiently, resulting in the formation of fine grains, which may result in poor magnetic properties and a very high Vickers hardness. In addition, for example, if the hot-rolling annealing temperature exceeds 1100°C, the grains may grow excessively, resulting in a severe grain size deviation, excessive oxidation, and a very low Vickers hardness. Therefore, in one embodiment disclosed herein, the hot-rolling annealing temperature may be 950°C or more and 1100°C or less. More preferably, the hot-rolling annealing may be performed at a temperature of 950°C or more and 1000°C or less, and even more preferably, the hot-rolling annealing may be performed at a temperature of 980°C or more and 1000°C or less. At this time, the heating rate to the above-mentioned temperature may be preferably 20°C / s or more.

[0153] The hot-rolling annealing step may be performed for 30 seconds (s) or more and 120 seconds (s) or less. For example, if the hot-rolling annealing time is less than 30 seconds (s), the annealing may be insufficient, resulting in insufficient grain growth and a very high Vickers hardness. If it exceeds 120 seconds (s), the grain growth may be excessive and a very low Vickers hardness. Therefore, in one embodiment disclosed herein, the hot-rolling annealing time may be 30 seconds (s) or more and 120 seconds (s) or less. More preferably, the hot-rolling annealing may be performed for 60 seconds or more and 100 seconds or less, and even more preferably, the hot-rolling annealing may be performed for 80 seconds or more and 90 seconds or less. At this time, the cooling rate may be preferably 30°C / s or more.

[0154] In addition, preferably, pickling may be performed to remove the oxide layer formed on the annealed hot-rolled steel sheet before the cold rolling described below after the hot-rolled annealing step. For example, the pickling may be performed by supplying a pickling solution prepared by using hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, or the like, alone or in combination, to a pickling tank where the solution reacts with the steel sheet, thereby reacting fine residual scales that are not removed by mechanical methods.

[0155] The cold rolling step may be a step of forming a cold rolled steel sheet by cold rolling the hot rolled and annealed hot rolled steel sheet.

[0156] The cold rolling step may be a cold rolling process in which the hot rolled steel sheet performed in the hot rolling annealing step is rolled at a temperature below the recrystallization temperature to further thin the thickness of the steel sheet.

[0157] The cold rolling step may be a step of rolling a hot-rolled annealed hot-rolled steel sheet into a cold-rolled steel sheet having a thickness of 0.3 mm or less (excluding 0 mm). If the thickness of the cold-rolled steel sheet exceeds 0.3 mm, the space factor of the motor may decrease during motor manufacturing, so the cold rolling may be controlled to form a cold-rolled steel sheet having a thickness of 0.3 mm or less (excluding 0 mm). In addition, the lower limit of the thickness of the cold-rolled steel sheet is not particularly limited, but may be 0.2 mm or more. In addition, the reduction ratio of the cold rolling may be controlled to be 70% or more and 95% or less.

[0158] The cold rolling annealing step may be a step of forming a cold rolled steel sheet by annealing the cold rolled steel sheet.

[0159] The cold rolling annealing step may be performed at a temperature of 800°C or higher and 1100°C or lower. For example, if the cold rolling annealing temperature is lower than 800°C, the grains may not grow sufficiently, resulting in the formation of fine grains, which may significantly increase the Vickers hardness of the steel sheet. In addition, for example, if the cold rolling annealing temperature exceeds 1100°C, the grains may grow excessively, resulting in a significant decrease in the Vickers hardness, and the grain size deviation may be significant, which may increase eddy current loss. Therefore, in one embodiment disclosed herein, the cold rolling annealing temperature may be 850°C or higher and 1050°C or lower. In this case, the heating rate to the above-described temperature may preferably be 10°C / s or higher.

[0160] In addition, the cold rolling annealing according to the present invention can control the heat treatment time according to the final annealing temperature. Preferably, the heat treatment can be performed for 30 seconds (s) or more and 400 seconds (s) or less in the above-mentioned temperature range. After the heat treatment, the cooling rate is preferably 20°C / s or more. If the heat treatment time during the cold rolling annealing is less than 30 seconds (s), the annealing is insufficient, the grains do not grow sufficiently, and the Vickers hardness of the steel sheet may become very high, and if it exceeds 400 seconds (s), the grains may grow excessively, and the Vickers hardness may become very low. More preferably, the cold rolling annealing can be performed for 5 seconds or more and 600 seconds or less, and even more preferably, the cold rolling annealing can be performed for 50 seconds or more and 150 seconds or less, and even more preferably, the cold rolling annealing can be performed for 90 seconds or more and 120 seconds or less. At this time, a cooling rate of 20 ℃ / s or more may be desirable.

[0161] In the case of electrical steel sheets, a nitride layer or an oxide layer is formed on the surface depending on the atmosphere during cold rolling annealing. For example, if hydrogen (H2) is not added during cold rolling annealing, a nitride layer may be formed. In addition, for example, if cold rolling annealing is performed in an atmosphere with a nitrogen (N2) fraction of 100%, the nitrogen present in the atmosphere may combine with aluminum (Al) in the steel, thereby forming a nitride such as AlN or a nitride layer including AlN. Therefore, in one embodiment disclosed herein, cold rolling annealing of a non-oriented electrical steel sheet may be performed in a mixed atmosphere including hydrogen and nitrogen. For example, the cold rolling annealing step of the method for manufacturing a non-oriented electrical steel sheet according to one embodiment disclosed herein may preferably be performed in an atmosphere with a hydrogen (H2) fraction of 10% or more and the remainder being nitrogen (N2). The surface of the cold-rolled annealed steel sheet can be smoothed through the mixed atmosphere of hydrogen (H2) and nitrogen (N2). When the hydrogen (H2) fraction is less than 10%, nitrogen (N) can penetrate the steel plate surface to form nitrides, which can increase iron loss. Here, the fraction can mean the volume fraction.

[0162] The steel sheet manufactured after the above cold rolling annealing step can satisfy the following equation 1.

[0163] Equation 1 is an equation for controlling the content of tin (Sn) and yttrium (Y), which are resistivity elements among the alloy components of the slab, and as described above, the content of the alloy components disclosed in the non-oriented electrical steel sheet does not substantially change during the manufacturing process. That is, since the alloy components of the slab and the alloy components of the non-oriented electrical steel sheet manufactured after the cold rolling annealing step are substantially the same, Equation 1 can be equally applied to the slab or the steel sheet manufactured after the cold rolling annealing step.

[0164] [Formula 1]

[0165] 0 < [Sn] + [Y] ≤ 0.0050

[0166] In Equation 1, [Sn] and [Y] represent the contents of Sn and Y in wt%, respectively.

[0167] Equation 1 may indicate that the sum of the contents of [Sn] and [Y] corresponding to resistivity elements must be controlled even within the content range disclosed herein. For example, Equation 1 may be controlled so that breakage of the sheet does not occur in the cold rolling step to further thin the thickness of the steel sheet by rolling the hot-rolled steel sheet performed in the hot-rolling annealing step. For example, if the value of Equation 1 exceeds 0.0050 wt%, even if a high resistivity can be secured, fine Sn-Y precipitates may be excessively precipitated, hindering domain wall movement and causing grain refinement, thereby increasing hardness. Accordingly, if the value of Equation 1 exceeds 0.0050 wt%, the non-oriented electrical steel sheet may break during cold rolling. Therefore, the value of Equation 1 may be within a range of more than 0 wt% and less than or equal to 0.0050 wt%.

[0168] The steel sheet manufactured after the above cold rolling annealing step may have a Vickers hardness within a range of 100 HV or more and 190 HV or less. The Vickers hardness of the steel sheet may be the Vickers hardness of the steel sheet obtained through the alloy component and / or manufacturing method according to an embodiment disclosed in the present specification. The description of the Vickers hardness is the same as that described in the non-oriented electrical steel sheet according to an embodiment disclosed in the present specification.

[0169] The steel sheet manufactured after the above cold rolling annealing step may have a resistivity greater than a certain value. The resistivity can be calculated using the following equation 3.

[0170] [Formula 3]

[0171] 10.1169 + 11.7499*[Si] + 8.76*[Al] + 6.1985*[Mn] - 10.3715*[S] + 14.3269*[P] + 1317*([Sn]+[Y])

[0172] In Equation 3, [Si], [Al], [Mn], [S], [P], [Sn] and [Y] represent the contents of Si, Al, Mn, S, P, Sn and Y, respectively, in wt%.

[0173] Equation 3 is a formula for controlling the content of the alloy component of the slab. As described above, the content of the alloy component disclosed in the non-oriented electrical steel sheet does not substantially change during the manufacturing process. That is, since the alloy component of the slab and the alloy component of the non-oriented electrical steel sheet manufactured after the cold rolling annealing step are substantially the same, Equation 3 can be equally applied to the slab or the steel sheet manufactured after the cold rolling annealing step.

[0174] The steel sheet manufactured after the above cold rolling annealing step may have a resistivity or a value of the above formula 3 of 60 μΩ·cm or more. The resistivity of the steel sheet may be the resistivity of the steel sheet obtained through the alloy component and / or manufacturing method according to an embodiment disclosed in the present specification. The description of the resistivity is the same as that described in the non-oriented electrical steel sheet according to an embodiment disclosed in the present specification.

[0175] The steel sheet manufactured after the above cold rolling annealing step may have a grain size in the range of 110 ㎛ to 200 ㎛. The grain size of the steel sheet may be the grain size of the steel sheet obtained through the alloy component and / or manufacturing method according to an embodiment disclosed in the present specification. The description of the grain size is as described in the non-oriented electrical steel sheet according to an embodiment disclosed in the present specification.

[0176] The steel sheet manufactured after the above cold rolling annealing step can satisfy the following equation 2.

[0177] [Formula 2]

[0178] 80 ≤ HV - {(100 × ρ) / d} ≤ 140

[0179] In Equation 2, HV is Vickers hardness, ρ is calculated by Equation 3, and d is grain size (㎛). Equation 2 is an equation that controls the Vickers hardness, resistivity, and grain size of the steel sheet manufactured after the above-described slab or cold-rolled annealing step, and may correspond to an equation that controls the non-oriented electrical steel sheet according to an embodiment disclosed in the present specification to secure low iron loss and rollability. When Equation 2 is less than 80, the resistivity may be large, making it difficult to secure iron loss, and when Equation 2 exceeds 140, the Vickers hardness may be very large, and fracture may occur during cold rolling. Therefore, the value of Equation 2 may be within a range of 80 to 140.

[0180] However, even if Equation 2 is satisfied, low core loss and cold rollability cannot be secured at the same time. For example, even if the value of Equation 2 is within the range of 80 to 140, if the value of Equation 1 described above exceeds the range of the present invention, fracture may occur during cold rolling. In addition, for example, even if the value of Equation 2 is within the range of 80 to 140, if the alloy component and its content described above exceed the range of the present invention, it may be difficult to secure the resistivity or low core loss of the steel sheet. Therefore, the non-oriented electrical steel sheet manufactured after the cold rolling annealing step of the method for manufacturing a non-oriented electrical steel sheet according to an embodiment disclosed in the present specification can secure low core loss and cold rollability at the same time when the slab having the alloy component described above satisfies Equation 1 and Equation 2 satisfies the above range.

[0181] The steel sheet manufactured after the above cold rolling annealing step can satisfy the following equation 4.

[0182] [Formula 4]

[0183] 0 < [Si] + [Al] ≤ 4.5

[0184] In Equation 4, [Si] and [Al] represent the contents of Si and Al, respectively, in wt%. Since the alloy composition of the slab and the alloy composition of the non-oriented electrical steel sheet manufactured after the cold-rolled annealing step are substantially the same, Equation 4 can be equally applied to the slab or the steel sheet manufactured after the cold-rolled annealing step. The description of Equation 4 is the same as that described in the non-oriented electrical steel sheet according to one embodiment disclosed in the present specification described above.

[0185] The steel sheet manufactured after the above cold rolling annealing step has a core loss (W 10 / 400 ) can have a low iron loss characteristic of 14.3 W / kg or less. The iron loss (W 10 / 400 ) is not particularly limited, but in one embodiment disclosed herein, the core loss (W) of the non-oriented electrical steel sheet 10 / 400 ) may be greater than or equal to 11.4 W / kg.

[0186] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present disclosure may further include a step of forming a coating layer after the cold-rolled annealing step. The coating layer is a coating formed on the surface of the cold-rolled steel sheet after cold rolling annealing, and may be referred to as an insulating film. Since the insulating film is widely known, a detailed description thereof will be omitted. The coating step may be performed using a process known in the relevant technical field.

[0187]

[0188] A non-oriented electrical steel sheet manufactured using a method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention can have low iron loss and no fracture during cold rolling.

[0189]

[0190] Experimental example

[0191] Hereinafter, the present application will be described in more detail through examples according to the present application and comparative examples not according to the present application, but the scope of the present application is not limited by the examples presented below.

[0192] (Method for manufacturing non-oriented electrical steel sheet specimens)

[0193] Table 1 below shows the alloy components that make up the examples and comparative examples.

[0194] Among the alloy components, the units of Si, Al, and Mn are weight percent, and the units of C, S, N, Ti, P, Sn, and Y are ppm. The remainder other than the alloy components listed in Table 1 below includes iron (Fe).

[0195] SiAlMnCSNTiPSnYExample 13.021.290.3513101814821923Example 23.180.930.269151291031010Example 33.270.950.2617171813109138Example 43.540.900.28612511932023Example 53.520.980.205912711486Example 63 .670.830.2792061780617Example 73.231.210.34618146101126Example 83.200.920.311761212105811Comparative Example 12.870.910.36121215109486Comparative Example 23.741.170.271351117781710Comparative Example 33.471.320.22141061613882 5Comparative Example 43.141.500.216105181073630Comparative Example 53.320.950.389131213942728Comparative Example 63.640.840.2912168141372125Comparative Example 73.301.120.2313191810100427Comparative Example 83.151.270.2519914191011435Comparative Example 93.421.030. 3811142061192437Comparative Example 103.130.860.381914178107015Comparative Example 113.160.920.22186107135280Comparative Example 123.341.140.396161517101410Comparative Example 133.031.190.391912121413306Comparative Example 143.400.870.24121817139200

[0196] A cold-rolled steel sheet was manufactured by cold-rolling and annealing using a slab having an alloy composition according to Table 1 above through a process as shown in Table 2 below. Table 2 below shows the temperature, time, speed, and / or thickness after rolling in the non-oriented electrical steel sheet process, which is performed in the order of hot rolling, hot annealing, cold rolling, and cold annealing of examples and comparative examples.

[0197] The unit of temperature is ℃, the unit of time is s, the unit of speed is ℃ / s, the unit of reduction ratio is %, and the unit of thickness is mm.

[0198] Hot rolling, hot rolling, annealing, cold rolling, cold rolling, annealing, reheating temperature, hot rolling temperature, coiling temperature, thickness, temperature, time, heating rate, reduction rate, thickness, temperature, time, Example 1, 100, 88, 600, 2.6, 98, 80, 300, 910, 24, 100, 120, Example 2, 110, 86, 600, 2.4, 98, 80, 990, 0.25, 100, 120, Example 3, 110, 86, 570, 3.1, 98, 80, 1390, 20, 100, 120, Example 4, 110, 86, 630, 2.2, 98, 80, 118, 80, 27, 100, 120, Example 5, 110, 85, 750, 1.9, 98, 80, 780, 0.24, 850, 120 Example 6110085057039808017920.241050120Example 711009006202.4980806900.231000120Example 8110088071029808012870.261000120Comparative Example 111008507002.19808010880.261000120Comparative Example 211009006002.49808017890.271000120Comparative Example 311008506702.39808016900. 241000120Comparative Example 411008606402.39808018890.251000120Comparative Example 5110086070029808013880.241000120Comparative Example 611008506402.59808014900.251000120Comparative Example 711008905603.29808010920.261000120Comparative Example 811008907201.99808019870.241000120Comparative Example 911008507201. 8980806860.261000120Comparative Example 1011008605902.7980808910.251000120Comparative Example 1111008905902.9980807910.261000120Comparative Example 1211008506502.39808017890.251000120Comparative Example 1311008706202.69808014910.241000120Comparative Example 1411008806602.59808013910.231000120

[0199] While manufacturing as in the process of Table 2 above, the cold-rolled annealing step was performed by heating the cold-rolled steel sheet to the cold-rolled annealing temperature of Table 2 above at a heating rate of 10°C / s in a mixed atmosphere of 40% nitrogen (N2) and 60% hydrogen (H2), maintaining it at this temperature for about 120 seconds, and then cooling it at a cooling rate of 20°C / s, thereby manufacturing cold-rolled annealed examples and comparative examples.

[0200] (Method for measuring the properties of non-oriented electrical steel sheets)

[0201] 1. Vickers hardness

[0202] For non-oriented electrical steel sheet specimens, Vickers hardness was measured by applying a load of 500 g for 15 seconds at room temperature (approximately 25°C) in accordance with the ASTM E-384 standard.

[0203]

[0204] 2. Grain size

[0205] Electron backscatter diffraction (EBSD) test specimens measuring 20 mm in width and 20 mm in length were manufactured to observe the ND plane (Normal direction plane) of a non-oriented electrical steel sheet specimen, and grains were measured by applying a step size of 5 ㎛ to the EBSD measurement for the ND plane according to the unit area. The EBSD measurements were performed on approximately 5,000 grains and then averaged to derive the grain size.

[0206]

[0207] 3. Fracture evaluation during cold rolling

[0208] Cross-sections of non-oriented electrical steel sheets were photographed using a scanning electron microscope (SEM) to confirm whether fracture occurred during cold rolling.

[0209] If no fracture occurred during cold rolling, it was judged as “X”, and if fracture occurred, it was judged as “O”.

[0210] At this time, the cross-section refers to a cross-section taken from the side after cutting a non-oriented electrical steel plate in the direction of its thickness.

[0211]

[0212] 4. Iron hand

[0213] It was measured based on the test method specified in the IEC 60404-2 international standard, and the core loss (W) was measured using the Epstein frame test method. 10 / 400 ) was measured.

[0214] The non-oriented electrical steel sheets manufactured in the examples and comparative examples were cut into sizes of (300±0.5) mm in length and (30±0.2) mm in width to prepare iron loss measurement test pieces. When cutting, half of the iron loss measurement test pieces were cut in a direction parallel to the rolling direction (RD, Rolling direction), and the other half were cut in a direction perpendicular to the rolling direction (TD, Transverse direction).

[0215] Afterwards, the iron loss measurement test pieces were prepared in multiples of four and measured using a double-overlapping method. At this time, the iron loss measurement test pieces were measured by inserting iron loss measurement test pieces cut in the same direction into the coil former so that they face each other.

[0216]

[0217] (Evaluation results of non-oriented electrical steel sheets)

[0218] For the above-mentioned manufactured examples and comparative examples, the values ​​of Equation 1, Equation 2 (= resistivity), Equation 3, Equation 4, Vickers hardness, grain size, occurrence of fracture during cold rolling, and iron loss were measured, and the results are summarized in Table 3 below.

[0219] The unit of the value or resistivity of Equation 2 is μΩ·cm, the unit of Vickers hardness is HV, the unit of crystal grain size is μm, and the unit of iron loss is W / kg.

[0220] Formula 1 Formula 2 Formula 3 Formula 4 Vickers hardness Grain size Fracture occurrence Iron loss Example 10.00 4 2 8 8.5 6 4.7 14.3 1 1 4 2 1 2 1 X 13.05 Example 20.00 2 0 8 6.96 0.0 1 4.1 1 1 3 1 1 3 6 X 13.14 Example 30.00 2 1 1 1 5.96 1.3 8 4.2 1 5 6 1 5 3 X 12.33 Example 40.00 4 3 1 2 5 4 6 7.1 2 4 4 1 7 2 1 4 4 X 11.86 Example 50.00 1 4 1 2 3 4 6 3.3 0 4.5 1 6 5 1 5 2 X 12.07 Example 60.00 23138.565.314.50188132X11.48Example 70.0018116.963.274.44155166X12.17Example 80.001992.760.344.12134146X14.21Comparative Example 10.001469.156.013.78121108X15.43Comparative Example 20.0027156.569.654.91197172O-Comparative Example 30.0033142.168.354.791 83167O-Comparative Example 40.006691.470.294.64159104O-Comparative Example 50.0055116.467.174.27164141O-Comparative Example 60.0046142.568.284.48195130O-Comparative Example 70.0049118.666.714.42172125X14.62Comparative Example 80.0049117.866.394.42176114X15.13Comparative Example 90.0061131.86 9.874.45191118O-Comparative Example 100.001575.758.903.99120133X14.51Comparative Example 110.002877.460.544.08121139X14.76Comparative Example 120.004199.667.294.48147142X14.44Comparative Example 130.000655.359.534.22108113X15.79Comparative Example 14075.459.294.27119136X14.87

[0221] Referring to Tables 1 to 3 above, Examples 1 to 8 satisfy both the alloy composition and its range, Equation 1 and Equation 2, according to one embodiment of the present invention. In addition, Examples 1 to 8 satisfy the alloy composition range, Equation 3 or Equation 4, according to one embodiment of the present invention.

[0222] In addition, it can be confirmed that Examples 1 to 8 have a resistivity of 60 μΩ·cm or more, and that cracks or fractures do not occur during cold rolling, and low iron loss can be secured.

[0223] On the other hand, Comparative Example 1 is an example in which the content of silicon among the alloy components according to one embodiment of the present invention falls short of the scope of the present invention and does not satisfy Equation 2. In Comparative Example 1, no cracks or fractures occur during cold rolling, but it can be confirmed that the value of Equation 2 does not fall short of the scope of the present invention and thus low iron loss is not secured.

[0224] Comparative Example 2 is an example in which the content of silicon among the alloy components according to one embodiment of the present invention exceeds the range of the present invention and does not satisfy Equations 2 and 4. In Comparative Example 2, it can be confirmed that the value of Equation 2 exceeds the range of the present invention and the value of Equation 4 also exceeds the range of the present invention, resulting in fracture during cold rolling.

[0225] Comparative Example 3 is an example that does not satisfy Equations 2 and 4 according to one embodiment of the present invention. In Comparative Example 3, it can be confirmed that the value of Equation 2 exceeds the range of the present invention, and the value of Equation 4 also exceeds the range of the present invention, resulting in fracture during cold rolling.

[0226] Comparative Example 4 is an example in which tin (Sn) among the alloy components according to one embodiment of the present invention exceeds the range of the present invention and does not satisfy Equations 1 and 4. In Comparative Example 4, it can be confirmed that the value of Equation 1 exceeds the range of the present invention and the value of Equation 4 also exceeds the range of the present invention, resulting in fracture during cold rolling.

[0227] Comparative Example 5 is an example in which the alloy component according to one embodiment of the present invention does not satisfy Equation 1. In Comparative Example 5, it can be confirmed that fracture occurred during cold rolling because the value of Equation 1 exceeded the range of the present invention. Through this, it can be confirmed that even if each of tin (Sn) and yttrium (Y) is within the range of the present invention, if the total content of resistivity elements exceeds the range of the present invention, the intended effect of the present invention cannot be achieved.

[0228] Comparative Example 6 is an example in which the alloy component according to one embodiment of the present invention does not satisfy Equation 2. In Comparative Example 6, it can be confirmed that fracture occurred during cold rolling because the value of Equation 2 exceeded the range of the present invention. Through this, it can be confirmed that even if each alloy component is within the range of the present invention, if the value of Equation 2 exceeds the range of the present invention, the intended effect of the present invention cannot be achieved.

[0229] Comparative Example 7 is an example in which tin (Sn) among the alloy components according to one embodiment of the present invention exceeds the range of the present invention, and Comparative Example 8 is an example in which yttrium (Y) among the alloy components according to one embodiment of the present invention exceeds the range of the present invention. Comparative Examples 7 and 8 have resistivities corresponding to the range of the present invention and do not cause fracture during cold rolling, but it can be confirmed that the low iron loss targeted by the present invention cannot be achieved. Through this, it can be confirmed that even if the total content of resistivity elements is within the range of the present invention, if each of the tin (Sn) and yttrium (Y) contents exceeds the range of the present invention, the low iron loss cannot be achieved.

[0230] Comparative Example 9 is an example in which yttrium (Y) among the alloy components according to one embodiment of the present invention exceeds the range of the present invention and does not satisfy Equation 1. In Comparative Example 9, it can be confirmed that fracture occurred during cold rolling because the value of Equation 1 exceeded the range of the present invention.

[0231] Comparative Example 10 is an example that does not include tin (Sn) among the alloy components according to one embodiment of the present invention and does not satisfy Equation 2, and Comparative Example 11 is an example that does not include yttrium (Y) among the alloy components according to one embodiment of the present invention and does not satisfy Equation 2. It can be confirmed that Comparative Examples 10 and 11 do not cause fracture during cold rolling, but cannot achieve the low iron loss desired by the present invention.

[0232] Comparative Example 12 is an example in which, among the alloy components according to one embodiment of the present invention, tin (Sn) exceeds the range of the present invention and yttrium (Y) is not included. In Comparative Example 12, although no fracture occurs during cold rolling, it can be confirmed that the low iron loss targeted by the present invention cannot be achieved. Through this, it can be confirmed that, even if the total content of resistivity elements is within the range of the present invention, if the tin (Sn) and yttrium (Y) contents each exceed the range of the present invention, low iron loss cannot be achieved.

[0233] Comparative Examples 13 and 14 are examples that do not include tin (Sn) and / or yttrium (Y) among the alloy components according to one embodiment of the present invention and do not satisfy Equation 2. In Comparative Example 13, since tin (Sn) is not included, it can be confirmed that the resistivity calculated by Equation 3 is inferior, and the value of Equation 2 is not within the range of the present invention, so low iron loss is not secured. In addition, in Comparative Example 14, since tin (Sn) and yttrium (Y) are not included, the value of Equation 1 is not within the range of the present invention, and the resistivity calculated by Equation 3 is inferior, and the value of Equation 2 is not within the range of the present invention, so low iron loss is not secured.

[0234] As described above, preferred embodiments of the present invention have been described. It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms, in addition to the embodiments described above, without departing from the spirit or scope thereof. Therefore, the above-described embodiments should be considered illustrative rather than restrictive, and accordingly, the present invention is not limited to the above description, but may be modified within the scope of the appended claims and their equivalents.

Claims

1. Contains 3.0 wt% or more of silicon (Si) and 3.7 wt% or less, 0.8 wt% or more of aluminum (Al) and 1.5 wt% or less, 0.2 wt% or more of manganese (Mn) and 0.4 wt% or less, 0.003 wt% or less of tin (Sn) (excluding 0 wt%), 0.003 wt% or less of yttrium (Y) (excluding 0 wt%), 0.002 wt% or less of sulfur (S) (excluding 0 wt%), 0.014 wt% or less of phosphorus (P) (excluding 0 wt%), and the remainder iron (Fe) and other unavoidable impurities. Non-oriented electrical steel sheet satisfying the following equations 1 and 2: [Formula 1] 0 < [Sn] + [Y] ≤ 0.0050 In Equation 1, [Sn] and [Y] represent the contents of Sn and Y in wt%, respectively. [Formula 2] 80 ≤ HV - {(100 × ρ) / d} ≤ 140 In Equation 2, HV is the Vickers hardness, ρ is calculated by Equation 3 below, and d is the grain size (㎛). [Formula 3] 10.1169 + 11.7499*[Si] + 8.76*[Al] + 6.1985*[Mn] - 10.3715*[S] + 14.3269*[P] + 1317*([Sn]+[Y]) In Equation 3, [Si], [Al], [Mn], [S], [P], [Sn] and [Y] represent the contents of Si, Al, Mn, S, P, Sn and Y, respectively, in wt%.

2. In paragraph 1, Non-oriented electrical steel sheet satisfying the following equation 4: [Formula 4] 0 < [Si] + [Al] ≤ 4.5 In Equation 4, [Si] and [Al] represent the contents of Si and Al, respectively, in wt%.

3. In paragraph 1, Non-oriented electrical steel sheet with a Vickers hardness of 100 HV or more and 190 HV or less.

4. In paragraph 1, Non-oriented electrical steel sheet with a resistivity of 60 μΩ·cm or more.

5. In paragraph 1, Non-oriented electrical steel sheet with a grain size of 110 ㎛ or more and 200 ㎛ or less.

6. In paragraph 1, Iron Loss (W 10 / 400 ) Non-oriented electrical steel sheet having a strength of 14.3 W / kg or less.

7. In paragraph 1, A non-oriented electrical steel sheet further comprising at least one of carbon (C) 0.002 wt% or less (excluding 0 wt%), nitrogen (N) 0.002 wt% or less (excluding 0 wt%), and titanium (Ti) 0.002 wt% or less (excluding 0 wt%).

8. A step of reheating and then hot-rolling a slab containing 3.0 wt% or more of silicon (Si) and 3.7 wt% or less, 0.8 wt% or more of aluminum (Al) and 1.5 wt% or less, 0.2 wt% or more of manganese (Mn) and 0.4 wt% or less, 0.003 wt% or less of tin (Sn) (excluding 0 wt%), 0.003 wt% or less of yttrium (Y) (excluding 0 wt%), 0.002 wt% or less of sulfur (S) (excluding 0 wt%), 0.014 wt% or less of phosphorus (P) (excluding 0 wt%), and the remainder iron (Fe) and other unavoidable impurities; a step of hot-rolling annealing; a step of cold-rolling; and a step of cold-rolling annealing. A method for manufacturing a non-oriented electrical steel sheet satisfying the following equations 1 and 2: [Formula 1] 0 < [Sn] + [Y] ≤ 0.0050 In Equation 1, [Sn] and [Y] represent the contents of Sn and Y in wt%, respectively. [Formula 2] 80 ≤ HV - {(100 × ρ) / d} ≤ 140 In Equation 2, HV is the Vickers hardness, ρ is calculated by Equation 3 below, and d is the grain size (㎛). [Formula 3] 10.1169 + 11.7499*[Si] + 8.76*[Al] + 6.1985*[Mn] - 10.3715*[S] + 14.3269*[P] + 1317*([Sn]+[Y]) In Equation 3, [Si], [Al], [Mn], [S], [P], [Sn] and [Y] represent the contents of Si, Al, Mn, S, P, Sn and Y, respectively, in wt%.

9. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet satisfying the following equation 4: [Formula 4] 0 < [Si] + [Al] ≤ 4.5 In Equation 4, [Si] and [Al] represent the contents of Si and Al, respectively, in wt%.

10. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the steel sheet manufactured after the above cold rolling annealing step has a Vickers hardness within a range of 100 HV or more and 190 HV or less.

11. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the steel sheet manufactured after the above cold rolling annealing step has a resistivity of 60 μΩ·cm or more.

12. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the steel sheet manufactured after the above cold rolling annealing step has a grain size within a range of 110 ㎛ or more and 200 ㎛ or less.

13. In paragraph 8, The steel sheet manufactured after the above cold rolling annealing step has a core loss (W 10 / 400 ) A method for manufacturing a non-oriented electrical steel sheet having a strength of 14.3 W / kg or less.

14. In paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, further comprising at least one of carbon (C) 0.002 wt% or less (excluding 0 wt%), nitrogen (N) 0.002 wt% or less (excluding 0 wt%), and titanium (Ti) 0.002 wt% or less (excluding 0 wt%).