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 one embodiment of the present invention, by controlling the residual amount of sulfur (S) according to the heat treatment time and the sulfur (S) content and by controlling grain size and the area fraction by crystallographic orientation, it is possible to provide a non-oriented electrical steel sheet having excellent magnetic properties and to provide a method for manufacturing same.

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] Recently, in accordance with global policies to reduce carbon dioxide emissions and prevent global warming, conventional internal combustion engine vehicles are being rapidly replaced by eco-friendly vehicles such as hybrid, electric, and hydrogen cars. Eco-friendly vehicles utilize electric motors to generate the driving force required for the vehicle and can reduce environmental pollution by significantly decreasing the emission of harmful exhaust gases.

[0003] As interest in and demand for such eco-friendly vehicles increase, the demand for electric motors, which generate the driving force for the vehicle, is also rising. An electric motor is a device that uses electricity to generate the driving force required for a vehicle, and energy efficiency—the ability to operate for a longer period using the same amount of energy—is a crucial technical factor.

[0004] To increase the energy efficiency of such electric motors, it is essential to improve the magnetic performance of the non-oriented electrical steel sheets used as the core material. Non-oriented electrical steel is a material that possesses uniform magnetic properties in all directions regardless of the rolling direction; to enhance energy efficiency, iron loss must be reduced and magnetic flux density increased.

[0005] In particular, magnetic flux density is determined by the arrangement of crystal grains. Specifically, it is desirable to uniformly create a texture having a {001} orientation, which facilitates magnetization due to the magnetic anisotropy of iron (Fe) atoms, throughout the sheet. Next, iron loss refers to the energy loss that occurs during the magnetization process of the material and can be expressed as the energy loss occurring at a specific magnetic flux density and frequency.

[0006] To satisfy low iron loss and high magnetic flux density, it is necessary to add silicon (Si) or appropriately control the thickness, grain size, texture, and precipitates. However, while adding silicon (Si) and reducing thickness can lower iron loss by increasing the electrical resistance of the material itself, it has the problem of lowering magnetic flux density. Since magnetic properties change sensitively depending on grain size, texture, and precipitates, variations in the manufacturing process lead to variations in magnetic properties. Because the motor core consists of multiple non-oriented electrical steel sheets laminated together, variations in magnetic properties can cause problems during motor processing.

[0007] Therefore, there is a need to develop non-oriented electrical steel sheets with low iron loss and technologies for manufacturing them by controlling the area fraction according to alloy composition, manufacturing process, grain size, and orientation.

[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 having excellent magnetic properties and a method for manufacturing a non-oriented electrical steel sheet by controlling the residual amount of sulfur (S) according to the sulfur (S) content and heat treatment time, and controlling the area fraction according to the grain size and orientation.

[0010] The problems of the present invention are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0011] A non-oriented electrical steel sheet according to one embodiment disclosed in this specification comprises silicon (Si) 3.0 wt% or more and 3.8 wt% or less, aluminum (Al) 0.8 wt% or more and 1.5 wt% or less, manganese (Mn) 0.7 wt% or more and 1.2 wt% or less, sulfur (S) 0.01 wt% or less (excluding 0 wt%), and the remainder being iron (Fe) and other unavoidable impurities, and satisfies Formula 1 below.

[0012] [Equation 1]

[0013]

[0014] In Equation 1, d is the grain size, and P{001}, P{111} and P{110} are the area fractions of grains having {001}, {111} and {110} orientations, respectively.

[0015] In addition, the grain size may be in the range of 3.00 mm or more and 8.00 mm or less.

[0016] In addition, the following Equation 2 may be 80% or more.

[0017] [Equation 2]

[0018]

[0019] In Equation 2, P{001}, P{111}, and P{110} are the area fractions of crystal grains having {001}, {111}, and {110} orientations, respectively.

[0020] In addition, sulfur (S) may be in the range of 0.0020 weight% or more and 0.0090 weight% or less.

[0021] In addition, it may further include at least one of carbon (C) 0.01 wt% or less (excluding 0 wt%), nitrogen (N) 0.01 wt% or less (excluding 0 wt%), titanium (Ti) 0.01 wt% or less (excluding 0 wt%), and phosphorus (P) 0.08 wt% or less (excluding 0 wt%).

[0022] In addition, Sn (tin) or Sb (antimony) may be further included in a range of 0.0001 wt% or more and 0.001 wt% or less.

[0023] Also, iron loss (W 10 / 400 ) may be 12 W / kg or less.

[0024] A method for manufacturing a non-oriented electrical steel sheet according to one embodiment disclosed in this specification comprises the steps of: reheating and hot-rolling a slab containing silicon (Si) 3.0 wt% or more and 3.8 wt% or less, aluminum (Al) 0.8 wt% or more and 1.5 wt% or less, manganese (Mn) 0.7 wt% or more and 1.2 wt% or less, sulfur (S) 0.01 wt% or less (excluding 0 wt%), and the remainder being iron (Fe) and other unavoidable impurities, in order to form a hot-rolled steel sheet; hot-rolling annealing the hot-rolled steel sheet in order to form a hot-rolled annealed steel sheet; cold-rolling the hot-rolled annealed steel sheet in order to form a cold-rolled steel sheet; and cold-rolling annealing the cold-rolled steel sheet in order to form a cold-rolled annealed steel sheet, and satisfying the following formula 3.

[0025] [Equation 3]

[0026]

[0027] In Equation 3, S0 is the sulfur (S) content (weight%) contained in the slab, ACLT is the time (h) of the cold rolling annealing step, and S R is the remaining amount (weight%) of sulfur (S) after the above cold rolling annealing step.

[0028] In addition, the hot rolling annealing step may be performed at a temperature of 900°C or higher and 1100°C or lower for 30 seconds or more and 120 seconds or less.

[0029] In addition, the cold rolling annealing step may be performed at a temperature of 950°C or higher and 1300°C or lower for 0.1 hours (h) or longer and 20 hours (h) or shorter.

[0030] In addition, the steel sheet produced after the above cold rolling and annealing step can satisfy the following Equation 1.

[0031] [Equation 1]

[0032]

[0033] In Equation 1, d is the grain size, and P{001}, P{111} and P{110} are the area fractions of grains having {001}, {111} and {110} orientations, respectively.

[0034] In addition, the steel sheet produced after the above cold rolling and annealing step may have a grain size in the range of 3.00 mm or more and 8.00 mm or less.

[0035] In addition, the steel sheet produced after the above cold rolling and annealing step may have at least 80% of the following Formula 2.

[0036] [Equation 2]

[0037]

[0038] In Equation 2, P{001}, P{111}, and P{110} are the area fractions of crystal grains having {001}, {111}, and {110} orientations, respectively.

[0039] In addition, sulfur (S) may be in the range of 0.0020 weight% or more and 0.0090 weight% or less.

[0040] In addition, the amount of sulfur (S) remaining after the above cold rolling annealing step may be in the range of 0.0005 weight% or more and 0.0030 weight% or less.

[0041] In addition, it may further include at least one of carbon (C) 0.01 wt% or less (excluding 0 wt%), nitrogen (N) 0.01 wt% or less (excluding 0 wt%), titanium (Ti) 0.01 wt% or less (excluding 0 wt%), and phosphorus (P) 0.08 wt% or less (excluding 0 wt%).

[0042] In addition, Sn (tin) or Sb (antimony) may be further included in a range of 0.0001 wt% or more and 0.001 wt% or less.

[0043] In addition, the steel sheet manufactured after the above cold rolling and annealing step has iron loss (W 10 / 400 ) may be 12 W / kg or less.

[0044] 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.

[0045] Specifically, by controlling the residual amount of sulfur (S) according to the sulfur (S) content and heat treatment time, and controlling the area fraction according to the grain size and orientation, it is possible to provide a non-oriented electrical steel sheet having excellent magnetic properties and a method for manufacturing a non-oriented electrical steel sheet.

[0046] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims.

[0047] Preferred embodiments of the present invention are described in detail below so that those skilled in the art can easily implement the invention. However, the present invention is not limited or restricted by the following embodiments.

[0048] Additionally, when it is stated that a component (or area, layer, part, etc.) is "on," "connected," or "combined" with another component, it means that it may be directly placed / connected / combined with the other component, or that a third component may be placed between them.

[0049] Terms such as "include" or "have" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0050] In order to clearly explain the present invention, detailed descriptions of related prior art that are irrelevant to the explanation or could unnecessarily obscure the essence of the invention have been omitted.

[0051] Furthermore, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0052] Unless otherwise specified, the notation 'A ~ B' or 'A to B' for numerical values ​​A and B means 'A or greater, B or less'. In such notation, if a unit is attached only to numerical value B, that unit also applies to numerical value A.

[0053] Also, unless specifically noted otherwise, 1 ppm is 0.0001 wt%.

[0054]

[0055] Non-oriented electrical steel sheets

[0056] A non-oriented electrical steel sheet according to one embodiment disclosed in this specification comprises silicon (Si) 3.0 wt% or more and 3.8 wt% or less, aluminum (Al) 0.8 wt% or more and 1.5 wt% or less, manganese (Mn) 0.7 wt% or more and 1.2 wt% or less, and sulfur (S) 0.01 wt% or less (excluding 0 wt%).

[0057] Hereinafter, the role and content of alloying elements included in the steel material of a non-oriented electrical steel sheet according to one embodiment disclosed in this specification will be described in detail.

[0058]

[0059] Silicon (Si)

[0060] Silicon (Si) is a major additive element in electrical steel sheets and can reduce iron loss by increasing the resistivity of the steel. On the other hand, if silicon is added in small amounts, the effect of improving iron loss may be insufficient. However, if silicon is added in excess, it may lead to a decrease in cold rolling performance due to increased brittleness. Therefore, it is necessary to appropriately control the silicon content.

[0061] When the silicon content is less than 3.0 wt%, the {001} texture does not develop smoothly during heat treatment, making it difficult to obtain high magnetic flux density and low iron loss characteristics, and the aforementioned effects cannot be expected. On the other hand, when the silicon content exceeds 3.8 wt%, problems such as a decrease in magnetic flux density and cracks and fractures during rolling may occur.

[0062] Accordingly, the steel according to one embodiment disclosed in this specification may contain silicon in an amount of 3.0 weight% or more and 3.8 weight% or less.

[0063]

[0064] Aluminum (Al)

[0065] Aluminum (Al) is an element that reduces iron loss by increasing resistivity, just like silicon (Si), and is a major additive element in electrical steel sheets, which are soft magnetic materials. Aluminum can play a role in reducing magnetic deviation by reducing magnetic anisotropy.

[0066] However, aluminum can combine with nitrogen to form nitrides such as AlN. If the aluminum content exceeds 1.5 weight%, problems such as nozzle clogging may occur during the continuous casting process, and problems such as cracking or fracture may occur during rolling. In addition, if the aluminum content is less than 0.8 weight%, it may be difficult to secure iron loss due to insufficient resistivity.

[0067] Accordingly, the steel according to one embodiment disclosed in this specification may contain aluminum in an amount of 0.8 weight% or more and 1.5 weight% or less.

[0068]

[0069] Manganese (Mn)

[0070] Manganese (Mn) is an element that improves magnetic properties by increasing resistivity and reducing iron loss, along with silicon (Si) and aluminum (Al).

[0071] When the manganese content is less than 0.7 wt%, sulfur (S) in the steel precipitates as fine MnS, which can hinder the growth of crystal grains favorable for magnetic properties. On the other hand, when the manganese content exceeds 1.2 wt%, coarse MnS precipitates, which can increase iron loss.

[0072] Accordingly, the steel according to one embodiment disclosed in this specification may contain manganese in an amount of 0.7 weight% or more and 1.2 weight% or less.

[0073]

[0074] Yellow (S)

[0075] Sulfur (S) is an impurity element in steel that is inevitably contained during the manufacturing process. If the sulfur (S) content exceeds 0.1 weight%, precipitates such as MnS and CuS may form inside the steel sheet when the same process is performed. Furthermore, if a large amount of sulfur (S) is added or a large amount remains after the process, it can induce the growth of crystal grains that are unfavorable to magnetic properties. Large amounts of precipitates and crystal grain growth unfavorable to magnetic properties can increase iron loss.

[0076] Accordingly, a non-oriented electrical steel sheet according to one embodiment disclosed in this specification may contain sulfur in an amount of 0.01 weight% or less (excluding 0 weight%).

[0077] More specifically, the non-oriented electrical steel disclosed in this specification may have an upper limit of sulfur (S) content of approximately 0.0100 wt%, 0.0090 wt%, 0.0085 wt%, 0.0080 wt%, 0.0075 wt%, 0.0070 wt%, 0.0065 wt%, 0.0060 wt%, or 0.0055 wt%, and a lower limit of approximately 0.0001 wt%, 0.0010 wt%, 0.0015 wt%, 0.0020 wt%, 0.0030 wt%, 0.0040 wt%, 0.0050 wt%, or 0.0055 wt%. The sulfur (S) content may be within a range of or less than or above the aforementioned upper limit, or or above or above the aforementioned lower limit.

[0078]

[0079] In addition, according to one embodiment disclosed in this specification, the steel may further include at least one of carbon (C) 0.01 wt% or less (excluding 0 wt%), nitrogen (N) 0.01 wt% or less (excluding 0 wt%), titanium (Ti) 0.01 wt% or less (excluding 0 wt%), and phosphorus (P) 0.08 wt% or less (excluding 0 wt%).

[0080]

[0081] Carbon (C)

[0082] Carbon (C) can increase iron loss by combining with titanium (Ti) and niobium (Nb) to form carbides such as TiC and NbC, so it is desirable to have as little as possible. If carbon exceeds 0.01 weight%, it can cause magnetic aging and degrade magnetic properties.

[0083] Accordingly, a non-oriented electrical steel sheet according to one embodiment disclosed in this specification may contain carbon in an amount of 0.01 weight% or less. Preferably, it may further contain more than 0 weight% and less than or equal to 0.01 weight%.

[0084]

[0085] Nitrogen (N)

[0086] Nitrogen (N) combines with aluminum (Al) and titanium (Ti) to form precipitates such as AlN and TiN, which increase iron loss and inhibit grain growth. Therefore, it is desirable to add as little nitrogen as possible.

[0087] Accordingly, a non-oriented electrical steel sheet according to one embodiment disclosed in this specification may contain nitrogen (N) in an amount of 0.01 weight% or less. Preferably, it may further contain more than 0 weight% and less than or equal to 0.01 weight%.

[0088]

[0089] Titanium (Ti)

[0090] Titanium (Ti) is an element with a very strong tendency to form precipitates in steel. It combines with carbon (C) or nitrogen (N) to form precipitates such as TiC and TiN, which inhibit grain growth. Since increasing the amount of titanium degrades magnetic properties, it is desirable to add it as low as possible.

[0091] Accordingly, a non-oriented electrical steel sheet according to one embodiment disclosed in this specification may contain titanium (Ti) in an amount of 0.01 weight% or less. Preferably, it may further contain more than 0 weight% and less than or equal to 0.01 weight%.

[0092]

[0093] Ph(P)

[0094] Phosphorus (P) is a grain boundary segregation element that improves texture, thereby increasing resistivity and contributing to lowering iron loss.

[0095] However, if the phosphorus content exceeds 0.08 weight%, it may form excessive grain boundary segregation, inhibit grain growth, and cause deterioration of magnetic properties and reduced cold rolling performance.

[0096] Accordingly, the non-oriented electrical steel sheet according to one embodiment disclosed in this specification may further contain phosphorus (P) in an amount of 0.08 weight% or less. Preferably, it may further contain more than 0 weight% and less than or equal to 0.08 weight%.

[0097]

[0098] In addition, according to one embodiment disclosed in this specification, the steel may further contain Sn (tin) or Sb (antimony) in a range of 0.01 weight% or more and 0.1 weight% or less.

[0099]

[0100] Tin (Sn) and antimony (Sb)

[0101] Tin (Sn) and antimony (Sb) are precipitating elements that form precipitates on the surface of a steel sheet and can be concentrated in the surface layer of the steel sheet. In this case, the concentrated tin and antimony can reduce iron loss by suppressing the adsorption of nitrogen and suppressing the formation of nitrides. However, if the content of one or more of tin and antimony is less than 0.0001 weight%, the above-described effect cannot be expected, and if it exceeds 0.001 weight%, the grain boundaries may become embrittled due to excessive precipitate formation, which may reduce fatigue resistance. Therefore, a non-oriented electrical steel sheet according to one embodiment disclosed in this specification may further include Sn (tin) or Sb (antimony) in an amount of 0.0001 weight% or more and 0.001 weight% or less.

[0102] In addition, more preferably, a non-oriented electrical steel sheet according to one embodiment disclosed in this specification may contain tin (Sn) in a range of 0.0001 weight% or more and 0.001 weight% or less.

[0103]

[0104] In addition to the components of the steel described above, the remainder may contain Fe and unavoidable impurities. 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 explanation is omitted.

[0105] 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. If additional elements are included, they may be included to replace the remainder of Fe.

[0106] A non-oriented electrical steel sheet according to one embodiment disclosed in this specification can satisfy the following Equation 1.

[0107] [Equation 1]

[0108]

[0109] In Equation 1, d is the grain size, and P{001}, P{111} and P{110} are the area fractions of grains having {001}, {111} and {110} orientations, respectively.

[0110] For example, Equation 1 is a relationship that controls the area fraction according to grain orientation along with grain size. Equation 1 relates to the content of sulfur (S) in the aforementioned alloy composition and / or the residual amount of sulfur (S) remaining during the process. When a large amount of sulfur (S) is dissolved in the steel in an atomic state, sulfur (S) may be concentratedly segregated on the surface of the steel sheet during cold rolling annealing. In this case, the surface energy of grains having {111} or {110} orientations may be lower than that of grains having {001} orientations. Accordingly, during cold rolling annealing, the growth of grains having {111} or {110} orientations may be promoted more than the growth of grains having {001} orientations. That is, if the sulfur (S) content is not appropriate, the grains may become coarse, or the growth of grains having {111} or {110} orientations may degrade magnetic properties. Therefore, magnetic properties can be secured by controlling the area fraction according to the appropriate grain size and grain orientation.

[0111] The lower limit of Formula 1 of the non-oriented electrical steel sheet according to one embodiment disclosed in this specification may be approximately 80, 90, 100, 101, 102, 103, 104, 105, 106, 107, 108, or 109, and the upper limit may be approximately 115, 114, 113, 112, 111, 110, 109, 108, 107, 106, 105, 104, 103, 102, or 101. The value of Formula 1 may be within a range greater than or equal to the aforementioned lower limit or less than or equal to the aforementioned upper limit. If the value of Equation 1 exceeds the aforementioned upper limit, the grain size becomes coarse, and the eddy current loss increases, which may lead to an increase in iron loss; if it falls short of the aforementioned lower limit, it may be difficult to secure grains with an orientation favorable to magnetic characteristics, which may lead to an increase in iron loss.

[0112] A non-oriented electrical steel sheet according to one embodiment disclosed in this specification may have a grain size in the range of 3.00 mm or more and 8.00 mm or less. Preferably, the grain size may be in the range of 3.5 mm or more and 7.5 mm or less, and more preferably, the grain size may be in the range of 4.3 mm or more and 7.3 mm or less. If the grain size does not fall below the lower limit of the above range, it may hinder domain wall movement, and if it exceeds the upper limit, eddy current loss may increase, which may lead to an increase in iron loss. The grain size of the non-oriented electrical steel sheet according to one embodiment disclosed in this specification may refer to the average grain diameter. The average grain diameter is determined according to the '1. Average Grain Diameter' method disclosed in the experimental example described below.

[0113] A non-oriented electrical steel sheet according to one embodiment disclosed in this specification may satisfy a value greater than or equal to a certain value of the following Equation 2.

[0114] [Equation 2]

[0115]

[0116] In Equation 2, P{001}, P{111}, and P{110} are the area fractions of crystal grains having {001}, {111}, and {110} orientations, respectively.

[0117] The method for measuring the area fraction of grains having {001}, {111}, and {110} orientations is based on the ‘2. Grain Area Fraction’ method disclosed in the experimental example described below. Equation 2 represents the ratio of the grain area fraction of the steel sheet, and may be 80% or more, 82% or more, 84% or more, 86% or more, 88% or more, or 90% or more. If the value of Equation 2 does not reach the above value, the magnetic properties of the steel sheet may be inferior as the grains having {111} or {110} orientations remain in a stable state.

[0118] In one embodiment disclosed in this specification, the non-oriented electrical steel sheet has iron loss (W10 / 400 ) may be a non-oriented electrical steel sheet having low iron loss characteristics of 12 W / kg or less. The above iron loss (W 10 / 400 Although the lower limit of ) is not specifically restricted, in one embodiment disclosed herein, the iron loss (W of the non-oriented electrical steel sheet) 10 / 400 The lower limit of ) may be 0.1 W / kg or more, 1 W / kg or more, or 9 W / kg or more. Iron loss (W 10 / 400 ) refers to the iron loss when a magnetic flux density of 1.0T is induced at a frequency of 400Hz, and is based on the method measured according to ‘3. Iron Loss’ disclosed in the experimental example described below.

[0119]

[0120] Method for manufacturing non-oriented electrical steel sheets

[0121] The present invention also relates to a method for manufacturing non-oriented electrical steel sheets.

[0122] The method for manufacturing a non-oriented electrical steel sheet disclosed in this specification comprises: a hot rolling step of manufacturing a hot-rolled steel sheet by reheating a slab containing the alloy components described above and then hot-rolling it; a step of hot-rolling annealing the hot-rolled steel sheet to form a hot-rolled annealed hot-rolled steel sheet; a step of cold-rolling the hot-rolled annealed hot-rolled steel sheet to form a cold-rolled steel sheet; and a step of cold-rolling annealing the cold-rolled steel sheet to form a cold-rolled annealed cold-rolled steel sheet.

[0123] As the content of the alloy components has been explained previously, a redundant explanation is omitted. Below, each step of the method for manufacturing a non-oriented electrical steel sheet according to one embodiment disclosed in this specification will be described in detail.

[0124] The hot rolling step may include the step of manufacturing a slab corresponding to a semi-finished product by designing the alloy composition within the range of the alloy composition described above, the step of reheating the slab, and the step of manufacturing a hot-rolled steel sheet by hot rolling after reheating.

[0125] In one example, the slab may contain silicon (Si) 3.0 wt% or more and 3.8 wt% or less, aluminum (Al) 0.8 wt% or more and 1.5 wt% or less, manganese (Mn) 0.7 wt% or more and 1.2 wt% or less, sulfur (S) 0.01 wt% or less (excluding 0 wt%), and the remainder being iron (Fe) and other unavoidable impurities.

[0126] In addition, the slab may further include at least one of carbon (C) 0.01 wt% or less (excluding 0 wt%), nitrogen (N) 0.01 wt% or less (excluding 0 wt%), titanium (Ti) 0.01 wt% or less (excluding 0 wt%), and phosphorus (P) 0.08 wt% or less (excluding 0 wt%).

[0127] In addition, according to one embodiment disclosed in this specification, the slab may further include Sn (tin) or Sb (antimony) in a range of 0.0001 weight% or more and 0.001 weight% or less.

[0128] In addition, the manufacture of slabs can be carried out using processes known in the relevant technical field, such as steelmaking processes and continuous casting processes.

[0129] Slab reheating may be performed at a temperature of 1000°C or higher and 1150°C or lower. If the reheating temperature is below 1000°C, excessive force is required during hot rolling, which may strain the equipment or make smooth hot rolling difficult. Additionally, if the reheating temperature exceeds 1150°C, surface oxidation of the steel or slab may occur, and precipitates may be redissolved. Such redissolution of precipitates may inhibit grain growth during the rolling or annealing steps described later, or finely reprecipitate, thereby increasing iron loss. Therefore, in one embodiment disclosed in this specification, the reheating temperature may be 1000°C or higher and 1150°C or lower.

[0130] Hot rolling may include rough rolling and finish rolling. Here, rough rolling may refer to making steel into a rolled material having a suitable shape, thickness, and width, and finish rolling may refer to adjusting the steel to a predetermined thickness and width and rolling it at a finishing temperature suitable for the application to achieve a good surface and shape.

[0131] At this time, the finishing temperature of the hot rolling process may be carried out at a temperature for forming a uniform structure and improving appropriate strength, and preferably, the finishing temperature may be 800°C or higher and 900°C or lower. For example, if the finishing temperature is less than 800°C, rolling is performed in a two-phase region and a non-uniform structure may be formed, and if the finishing temperature exceeds 900°C, a problem may arise in which the strength or hardness of the steel material decreases rapidly. Accordingly, in one embodiment disclosed in this specification, the finishing temperature of the hot rolling process may be 800°C or higher and 900°C or lower.

[0132] Subsequently, 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 500°C or higher and 600°C or lower. If the coiling temperature is below 500°C, brittleness increases, which may cause fracture during the cold rolling or stamping process, and the grain size may become too small, preventing sufficient grain growth even after annealing. On the other hand, if the coiling temperature exceeds 600°C, fine precipitates may be generated, which may degrade magnetic properties. Accordingly, in one embodiment disclosed herein, the coiling temperature of the hot rolling process may be 500°C or higher and 600°C or lower.

[0133] The thickness of the hot-rolled steel sheet formed through the step of hot-rolling the above steel material to form a hot-rolled steel sheet may be 1.6 mm or more and 2.3 mm or less. For example, if the thickness of the hot-rolled steel sheet is less than 1.6 mm, the thickness obtained after cold rolling is insufficient, which may cause shape defects when applied to products, and if the thickness of the hot-rolled steel sheet exceeds 2.3 mm, the cold rolling reduction ratio increases, and the fraction of texture unfavorable to magnetic properties increases, which may result in inferior magnetic properties. Accordingly, in one embodiment disclosed herein, the thickness of the hot-rolled steel sheet formed by performing reheating, hot rolling, and / or coiling processes may be 1.6 mm or more and 2.3 mm or less.

[0134] The step of hot rolling annealing may be a step of hot rolling annealing the hot rolled steel plate to form a hot rolled annealed steel plate.

[0135] The hot rolling annealing step may be performed at a temperature of 900°C or higher and 1100°C or lower. For example, if the hot rolling annealing temperature is below 900°C, the crystal grains may not grow sufficiently, resulting in the formation of fine crystal grains that may hinder domain wall movement. Additionally, for example, if the hot rolling annealing temperature exceeds 1100°C, the crystal grains may grow excessively, leading to increased eddy current losses. In one embodiment disclosed herein, the hot rolling annealing temperature may be 900°C or higher and 1100°C or lower. At this time, the heating rate to the above-mentioned temperature is preferably 10°C / s or higher.

[0136] The hot rolling annealing step may be performed for a period of 30 seconds or more and 120 seconds or less. For example, if the hot rolling annealing time is less than 30 seconds, the annealing may be insufficient and the crystal grains may not grow sufficiently, and if it exceeds 120 seconds, the crystal grains may grow excessively and the eddy current loss may increase. Therefore, in one embodiment disclosed herein, the hot rolling annealing time may be 30 seconds or more and 120 seconds or less. At this time, a cooling rate of 20 ℃ / s or more is preferred.

[0137] In addition, the atmosphere during the hot rolling annealing step may be a mixed atmosphere containing hydrogen (H2) and nitrogen (N2) or a 100% nitrogen (N2) atmosphere. More specifically, the atmosphere during the hot rolling annealing step may have a hydrogen (H2) fraction in the range of 80% or more and 100% or less.

[0138] In addition, preferably, pickling may be performed to remove the oxide layer formed on the annealed hot-rolled steel sheet after the hot-rolling annealing step and before the cold rolling described later. For example, the pickling may be performed by supplying a pickling solution, prepared by mixing hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, etc., or alone, to a pickling tank where the steel sheet reacts, thereby reacting fine residual scales that cannot be removed by mechanical means.

[0139] The cold rolling step may be a step of forming a cold-rolled steel sheet by cold-rolling the hot-rolled annealed steel sheet.

[0140] The cold rolling step may be a step of rolling a hot-rolled annealed steel sheet into a cold-rolled steel sheet having a thickness of 0.25 mm or less (excluding 0 mm). Since the packing density of the motor may decrease when the thickness of the cold-rolled steel sheet exceeds 0.25 mm, the cold rolling can be controlled to form a cold-rolled steel sheet having a thickness of 0.25 mm or less. In addition, although the lower limit is not specifically restricted, the lower limit of the thickness of the cold-rolled steel sheet may be 0.2 mm or more. In addition, the reduction rate of the cold rolling can be controlled to be 81% or more and 96% or less.

[0141] The step of cold rolling annealing may be a step of annealing the cold-rolled steel sheet to form a cold-rolled annealed steel sheet.

[0142] The cold rolling annealing step may be performed at a temperature of 950°C or higher and 1300°C or lower. For example, if the cold rolling annealing temperature is below 950°C, the grains may not grow sufficiently, resulting in the formation of fine grains that may hinder domain wall movement. Additionally, for example, if the cold rolling annealing temperature exceeds 1300°C, the grains may grow excessively, and the significant variation in grain size may lead to increased eddy current losses. Therefore, in one embodiment disclosed herein, the cold rolling annealing may be performed at a temperature of 950°C or higher and 1300°C or lower. At this time, the heating rate to the above-mentioned temperature is preferably 5°C / s or higher.

[0143] In addition, the cold rolling annealing step disclosed in this specification may control the heat treatment time by considering the sulfur (S) content. The cold rolling annealing step may perform heat treatment for a certain period of time within the aforementioned temperature range. After the heat treatment, a cooling rate of 20 °C / s or higher is preferred. The lower limit of the heat treatment time during cold rolling annealing may be approximately 0.1 hours (h), 0.3 hours (h), 0.7 hours (h), 1 hour (h), 5 hours (h), 7 hours (h), 10 hours (h), 14 hours (h), or 16 hours (h), and the upper limit may be approximately 20 hours (h), 16 hours (h), 14 hours (h), 10 hours (h), 7 hours (h), or 1 hour (h). The heat treatment time during cold rolling annealing may be within a range greater than or exceeding the aforementioned lower limit, or less than or below the aforementioned upper limit.

[0144] For example, if the heat treatment time in the cold rolling annealing stage is short relative to the sulfur (S) content, the residual sulfur (S) may be excessive, causing crystal grains with {111} or {110} orientations to stabilize and resulting in inferior magnetic properties. Additionally, if the heat treatment time in the cold rolling annealing stage is short relative to the sulfur (S) content, the small grain size may make domain wall movement difficult, leading to an increase in iron loss. Furthermore, if the heat treatment time in the cold rolling annealing stage is long relative to the sulfur (S) content, the residual sulfur (S) may be extremely small, causing crystal grains with {111} or {110} orientations to stabilize again and resulting in inferior magnetic properties, or even if crystal grains with {001} orientations are stabilized, the grain size may become coarse, leading to increased eddy current losses and an increase in iron loss. Therefore, the heat treatment time in the cold rolling annealing stage according to one embodiment disclosed herein can be appropriately controlled within the aforementioned range by considering the sulfur (S) content and / or the residual sulfur (S).

[0145] In addition, the cold rolling annealing step disclosed in this specification may have a residual amount of sulfur (S) within a certain range. The lower limit of the residual amount of sulfur (S) may be approximately 0.0005 wt%, 0.0006 wt%, 0.0007 wt%, 0.0008 wt%, 0.0009 wt%, 0.0010 wt%, or 0.0020 wt%, and the upper limit may be approximately 0.0030 wt%, 0.0025 wt%, 0.0020 wt%, 0.0015 wt%, or 0.0010 wt%. The residual amount of sulfur (S) may be within a range greater than or exceeding the aforementioned lower limit, or less than or below the aforementioned upper limit. If the residual amount of sulfur (S) exceeds the aforementioned upper limit, the {111} or {110} orientation may be stabilized, and iron loss may increase. The remaining amount of sulfur (S) can be controlled according to Equation 3 described below, and can also be controlled by considering the aforementioned alloy composition and the heat treatment time of the cold rolling annealing step.

[0146] In addition, a method for manufacturing a non-oriented electrical steel sheet according to one embodiment disclosed in this specification can satisfy the following Equation 3.

[0147] [Equation 3]

[0148]

[0149] In Equation 3, S0 is the sulfur (S) content (weight%) contained in the slab, ACLT is the time (h) of the cold rolling annealing step, and S R is the remaining amount (weight%) of sulfur (S) after the above cold rolling annealing step.

[0150] As described above, the sulfur (S) content contained in the slab, the cold rolling annealing time, and the residual sulfur (S) play an important role in controlling the grain size and / or grain orientation. Accordingly, the non-oriented electrical steel sheet according to one embodiment disclosed herein may satisfy a range of 10 or more and 40 or less. Additionally, preferably, the lower limit of Equation 3 may be 11 or more, and the upper limit may be 36 or less.

[0151] If the value of Equation 3 does not fall below the aforementioned lower limit, the heat treatment time of the cold rolling annealing step relative to the sulfur (S) content is short, so the residual sulfur (S) content may be high, and the iron loss may increase as the {111} or {110} orientation is stabilized. In addition, if the value of Equation 3 exceeds the aforementioned upper limit, the heat treatment time of the cold rolling annealing step relative to the sulfur (S) content is long, so the grain size becomes coarser, and the eddy current loss increases, which may increase the iron loss. Accordingly, in the method for manufacturing a non-oriented electrical steel sheet according to one embodiment disclosed in this specification, the heat treatment time of the cold rolling annealing step can be controlled to satisfy the aforementioned range by considering the sulfur (S) content and / or the residual sulfur (S).

[0152] The step of forming a cold-rolled annealed steel sheet by cold-rolling annealing a cold-rolled steel sheet can be performed in a mixed atmosphere containing hydrogen (H2) and nitrogen (N2).

[0153] In the case of non-oriented 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. Also, for example, if cold rolling annealing is performed in an atmosphere where the nitrogen (N2) fraction is 100%, the nitrogen present in the atmosphere combines with aluminum (Al) in the steel, and a nitride layer containing AlN or a nitride such as AlN may be formed. Accordingly, in one embodiment disclosed herein, the cold rolling annealing of a non-oriented electrical steel sheet may be performed in a mixed atmosphere containing hydrogen (H2) and nitrogen (N2), and more preferably, in a mixed atmosphere containing hydrogen (H2) at a fraction of 90% or more.

[0154] The steel sheet produced after the above cold rolling and annealing step can satisfy the following Equation 1.

[0155] [Equation 1]

[0156]

[0157] In Equation 1, d is the grain size, and P{001}, P{111} and P{110} are the area fractions of grains having {001}, {111} and {110} orientations, respectively.

[0158] In addition, the steel sheet produced after the above cold rolling and annealing step may have a grain size in the range of 3.00 mm or more and 8.00 mm or less.

[0159] In addition, the steel sheet produced after the above cold rolling and annealing step may have at least 80% of the following Formula 2.

[0160] [Equation 2]

[0161]

[0162] In Equation 2, P{001}, P{111}, and P{110} are the area fractions of crystal grains having {001}, {111}, and {110} orientations, respectively.

[0163] In addition, the steel sheet manufactured after the above cold rolling and annealing step has iron loss (W 10 / 400 ) may be 12 W / kg or less.

[0164] In the steel sheet produced after the cold rolling and annealing step of the method for manufacturing a non-oriented electrical steel sheet according to one embodiment disclosed in this specification, the description of Equation 1, grain size, Equation 2, and iron loss is the same as that described in the non-oriented electrical steel sheet according to one embodiment disclosed in this specification.

[0165]

[0166] Experimental Example

[0167] The present application will be described in more detail below through embodiments 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 embodiments presented below.

[0168] (Method for manufacturing non-oriented electrical steel specimens)

[0169] Table 1 below shows the alloy components constituting the examples and comparative examples. Additionally, Table 2 shows the sulfur (S) content among the alloy components for each example and comparative example. The remainder other than the alloy components listed in Tables 1 and 2 below includes iron (Fe). The unit of the alloy components is weight%.

[0170] SiMnAlCSPNTiSn3.30.90.90.0019 See Table 2 0.0008 0.0017 0.0016 0.0008

[0171] Sulfur (S) Content Examples Comparative Examples 0.0090 Examples 1 to 3 Comparative Examples 1 to 6 0.0055 Examples 4 and 5 Comparative Examples 7 to 13 0.0020 Examples 6 and 7 Comparative Examples 14 to 20

[0172] A slab having the alloy composition according to Tables 1 and 2 above was manufactured, and a non-oriented electrical steel sheet specimen was manufactured under the process conditions of Table 3 below.

[0173] In Table 3, the unit of temperature is °C, the unit of hot rolling annealing time is seconds (s), the unit of cold rolling annealing time is hours (h), the speed is °C / s, the unit of reduction rate is %, and the unit of thickness is mm.

[0174] Hot rolling, hot rolling, annealing, cold rolling, cold rolling, annealing, reheating, temperature, hot rolling, coiling temperature, thickness, temperature, time, reduction rate, thickness, temperature, time, cooling Example 1 1008465502.029919987.6230.2511991010 Example 2 11008455502.0899410187.9800.2512001412 Example 3 11008415502.0399710087.6840.2512011614 Example 4 11008485502.09919887.50.251198714 Example 5 11008425502.089949787.9800.2511991012 Example 6 11008415502.0498710187.740. 2511970.711 Example 7 11008415502.039889987.6840.251198115 Comparative Example 1 11008415502.049899887.7450.2511980.310 Comparative Example 2 11008495502.059879787.8040.2511960.511 Comparative Example 3 11008425502.079889987.9220.2511970.712 Comparative Example 4 11008435502.0999110088.0380.251196110 Comparative Example 5 11008445502.099 310187.50.251197511 Comparative Example 611008455502.0699910087.8640.251198713 Comparative Example 711008425502.0898810087.9800.2511970.310 Comparative Example 811008415502.0499310187.7450.2511980.511 Comparative Example 911008435502.059919987.8040.2511990.712 Comparative Example 1011008465502.0099310187.50.251200113 Comparative Example 11110 08495502.0699910087.8640.251197511Comparative Example 1211008465502.059979987.8040.2512001411Comparative Example 1311008455502.0498810087.7450.2512011610Comparative Example 1411008415502.0599310187.8040.2511990.310Comparative Example 1511008425502.0998910088.0380.2512000.512Comparative Example 1611008495502.099110187.50.251199514Comparative Example 1711008425502.069939887.8640.251200711Comparative Example 1811008435502.089999787.9800.2512011010Comparative Example 1911008435502.059919987.8040.2511991411Comparative Example 2011008465502.0499410087.7450.2512001610.

[0175] In the above process, the heating rate during hot rolling annealing is about 10 ℃ / s and the cooling rate is about 20 ℃ / s, and the heating rate during cold rolling annealing is about 10 ℃ / s.

[0176] In addition, the hot rolling annealing was performed under a nitrogen (N2) atmosphere, and the cold rolling annealing was performed under a mixed atmosphere of nitrogen (N2) and 90% hydrogen (H2).

[0177]

[0178] (Method for measuring the physical properties of non-oriented electrical steel specimens)

[0179] 1. Average grain diameter

[0180] Electron backscatter diffraction (EBSD) specimens were prepared and measured so that the ND plane (Normal direction plane) of a non-oriented electrical steel sheet specimen (60 mm wide x 60 mm long) could be observed. Subsequently, the EBSD measurement values ​​were analyzed using the analysis software TSL-OIM Analysis, and the average grain diameter of each specimen was derived.

[0181] At this time, the grain diameter of each test specimen was measured 16 times, and the average value of the average grain diameters obtained from the 16 measurements was calculated. The calculated average value was set as the average grain diameter of the present invention.

[0182]

[0183] 2. Grain area fraction

[0184] A test specimen for EBSD (Electron backscatter diffraction) measurement was prepared so that the TD plane (Transverse direction plane) of the steel plate could be observed. Subsequently, the EBSD measurements of the prepared test specimen were analyzed using the analysis software TSL-OIM Analysis to identify the grain orientations and derive the area fractions for each orientation.

[0185]

[0186] 3 Iron Hand ( )

[0187] Iron loss of the non-oriented electrical steel sheet specimen of the present invention ( ) was measured using an SST (Single Sheet Tester). More specifically, it was measured based on the test method specified in IEC 60404-3.

[0188] In this experiment, non-oriented electrical steel sheet specimens were 60×60 mm 2 A specimen of a certain size was fabricated, and the iron loss in the direction parallel to the rolling direction (RD, Rolling direction) and the direction perpendicular to the rolling direction (TD, Transverse direction) was measured, and the average value was used as the iron loss value of the specimen.

[0189]

[0190] 4. Remaining amount of sulfur (S)

[0191] The residual amount of sulfur (S) was measured through C / S analysis using a C / S Analyzer (Carbon-Sulfur Analyzer) (ELTRA GmbH, CS-2000).

[0192]

[0193] (Evaluation results of non-oriented electrical steel sheets)

[0194] For the above-mentioned examples and comparative examples, the values ​​of Equation 1, grain size, Equation 2, sulfur (S) residue, Equation 3, and iron loss were measured and summarized in Table 4 below.

[0195] The unit of grain size is μm, the unit of sulfur (S) remainder is % content, and the unit of iron loss is W / kg.

[0196] Formula 1. Grain Size Formula 2. Sulfur (S) Residue Formula 3. Iron Loss (W 10 / 400 Example 1 102.135.5870.00213011.78 Example 2 104.825.8880.000814.4310.2 Example 3 108.616.1900.000712.6311.8 Example 4 107.856.3880.000714.8610.6 Example 5 109.927.2840.000611.510.8 Example 6 100.254.3910.000735.579.8 Example 7 109.415.99 20.00062610.5 Comparative Example 153.000.02530.008138112.69 Comparative Example 251.000.06510.007625612.43 Comparative Example 348.320.8480.0058186.5712.39 Comparative Example 446.721.2460.004413412.25 Comparative Example 548.621.8470.00325012.44 Comparative Example 653.212.9490.002941.8612.36 Comparative Example 75 4.030.23540.0042225.3312.41Comparative Example 864.030.26640.002913912.86Comparative Example 967.813.1630.002199.5712.51Comparative Example 1072.453.3670.00177212.34Comparative Example 11128.728.8900.00014.9312.8Comparative Example 12133.618.9940.00025.4413.1Comparative Example 1356.071.46550 .001682.6712.23Comparative Example 1459.922.8560.00145412.36Comparative Example 15120.387.4930.0005913.2Comparative Example 16124.818.1920.00035.8613.1Comparative Example 17128.458.3940.0004613.33Comparative Example 18128.798.46930.00012.4312.97Comparative Example 19129.588.67920.00001.2513.12

[0197] Referring to Tables 1 to 4 above, Examples 1 to 7 satisfy the alloy composition range, Formula 1, and Formula 3 according to one embodiment of the present invention.

[0198] Examples 1 to 7 can be confirmed to have a stable {001} orientation due to an appropriate amount of residual sulfur (S) and an appropriate cold rolling annealing time relative to the sulfur (S) content. Additionally, Examples 1 to 7 can be confirmed to have an appropriate grain size. Through this, it can be confirmed that the non-oriented electrical steel sheet according to one embodiment disclosed in this specification, or the non-oriented electrical steel sheet manufactured according to the method for manufacturing a non-oriented electrical steel sheet, can secure iron loss.

[0199] On the other hand, Comparative Examples 1 to 6 are examples that do not satisfy the ranges of Formula 1 and Formula 3 according to one embodiment of the present invention. Comparative Examples 1 to 6 have the same S content as Examples 1 to 3, but the heat treatment time of the cold rolling annealing step is shorter relative to the S content. Accordingly, it can be confirmed that in Comparative Examples 1 to 6, the small grain size hinders domain wall movement, or the high residual S content stabilizes the {111} or {110} orientations, resulting in a small area fraction of grains having the {001} orientation and an increase in iron loss.

[0200] Comparative Examples 7 to 10 are examples that do not satisfy the ranges of Formulas 1 and 3 according to one embodiment of the present invention. Comparative Examples 7 to 10 have the same S content as Examples 4 and 5, but the heat treatment time of the cold rolling annealing step is shorter relative to the S content. Accordingly, in Comparative Examples 7 to 10, it can be confirmed that the iron loss increased because the area fraction of grains having the {001} orientation was small, which hinders domain wall movement, or because the residual amount of S is high, the {111} or {110} orientations are stabilized.

[0201] Comparative Examples 11 and 12 are examples that do not satisfy the ranges of Equations 1 and 3 according to one embodiment of the present invention. Comparative Examples 11 and 12 have the same S content as Examples 4 and 5, but the heat treatment time of the cold rolling annealing step is longer relative to the S content. Accordingly, in Comparative Examples 11 and 12, although the {001} orientation may be stable with an appropriate residual amount of S, it can be confirmed that the iron loss has increased due to the large grain size and increased eddy current loss.

[0202] Comparative Examples 13 and 14 are examples that do not satisfy the ranges of Equations 1 and 3 according to one embodiment of the present invention. Comparative Examples 13 and 14 have the same S content as Examples 6 and 7, but the heat treatment time of the cold rolling annealing step is shorter relative to the S content. Accordingly, in Comparative Examples 13 and 14, it can be confirmed that the iron loss increased because the area fraction of grains having the {001} orientation was small, which hinders domain wall movement, or because the residual S content was high, the {111} or {110} orientations were stabilized.

[0203] Comparative Examples 15 to 19 are examples that do not satisfy the ranges of Formulas 1 and 3 according to one embodiment of the present invention. Comparative Examples 15 to 19 have the same S content as Examples 4 and 5, but the heat treatment time of the cold rolling annealing step is longer relative to the S content. Accordingly, in Comparative Examples 15 to 19, although the {001} orientation may be stable with an appropriate residual amount of S, it can be confirmed that the iron loss has increased due to the large grain size and increased eddy current loss.

[0204]

[0205] As described above, preferred embodiments according to the present invention have been examined. It is obvious to those skilled in the art that, in addition to the embodiments described above, the present invention may be embodied in other specific forms without departing from its spirit or scope. Therefore, the embodiments described above should be regarded as illustrative rather than restrictive, and accordingly, the present invention is not limited to the description above but may be modified within the scope of the appended claims and their equivalents.

Claims

1. Containing silicon (Si) 3.0 wt% or more and 3.8 wt% or less, aluminum (Al) 0.8 wt% or more and 1.5 wt% or less, manganese (Mn) 0.7 wt% or more and 1.2 wt% or less, sulfur (S) 0.01 wt% or less (excluding 0 wt%), and the remainder being iron (Fe) and other unavoidable impurities, Non-oriented electrical steel sheet satisfying the following Equation 1: [Equation 1] In Equation 1, d is the grain size, and P{001}, P{111} and P{110} are the area fractions of grains having {001}, {111} and {110} orientations, respectively.

2. In Paragraph 1, Non-oriented electrical steel sheet having a grain size within the range of 3.00 mm or more and 8.00 mm or less.

3. In Paragraph 1, Non-oriented electrical steel sheet having 80% or more of the following Formula 2: [Equation 2] In Equation 2, P{001}, P{111}, and P{110} are the area fractions of crystal grains having {001}, {111}, and {110} orientations, respectively.

4. In Paragraph 1, Non-oriented electrical steel sheet having a sulfur (S) content in the range of 0.0020 wt% or more and 0.0090 wt% or less.

5. In Paragraph 1, A non-oriented electrical steel sheet further comprising at least one of carbon (C) 0.01 wt% or less (excluding 0 wt%), nitrogen (N) 0.01 wt% or less (excluding 0 wt%), titanium (Ti) 0.01 wt% or less (excluding 0 wt%), and phosphorus (P) 0.08 wt% or less (excluding 0 wt%).

6. In Paragraph 1, A non-oriented electrical steel sheet further containing Sn (tin) or Sb (antimony) in a range of 0.0001 weight% or more and 0.001 weight% or less.

7. In Paragraph 1, Iron loss (W 10 / 400 Non-oriented electrical steel sheet with a ) of 12 W / kg or less.

8. A step of reheating and then hot-rolling a slab containing silicon (Si) 3.0 wt% or more and 3.8 wt% or less, aluminum (Al) 0.8 wt% or more and 1.5 wt% or less, manganese (Mn) 0.7 wt% or more and 1.2 wt% or less, sulfur (S) 0.01 wt% or less (excluding 0 wt%), and the remainder being iron (Fe) and other unavoidable impurities, in order to form a hot-rolled steel sheet; A step of hot-rolling annealing the hot-rolled steel sheet to form a hot-rolled annealed steel sheet; A step of cold rolling the hot-rolled annealed hot-rolled steel sheet to form a cold-rolled steel sheet; and To form a cold-rolled annealed steel sheet, the method includes the step of cold-rolling annealing the cold-rolled steel sheet, and A method for manufacturing a non-oriented electrical steel sheet satisfying the following Equation 3: [Equation 3] In Equation 3, S0 is the sulfur (S) content (weight%) contained in the slab, ACLT is the time (h) of the cold rolling annealing step, and S R is the remaining amount (weight%) of sulfur (S) after the above cold rolling annealing step.

9. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above-mentioned hot rolling annealing step is performed at a temperature of 900°C or higher and 1100°C or lower for 30 seconds or more and 120 seconds or less.

10. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the above cold rolling annealing step is performed at a temperature of 950°C or higher and 1300°C or lower for 0.1 hours (h) or higher and 20 hours (h) or lower.

11. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the steel sheet produced after the above cold rolling and annealing step satisfies the following Equation 1: [Equation 1] In Equation 1, d is the grain size, and P{001}, P{111} and P{110} are the area fractions of grains having {001}, {111} and {110} orientations, respectively.

12. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the steel sheet produced after the above cold rolling and annealing step has a grain size within the range of 3.00 mm or more and 8.00 mm or less.

13. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the steel sheet produced after the above cold rolling and annealing step has 80% or more of the following Formula 2: [Equation 2] In Equation 2, P{001}, P{111}, and P{110} are the area fractions of crystal grains having {001}, {111}, and {110} orientations, respectively.

14. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet in which sulfur (S) is in the range of 0.0020 wt% or more and 0.0090 wt% or less.

15. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, wherein the residual amount of sulfur (S) after the above cold rolling annealing step is within the range of 0.0005 weight% or more and 0.0030 weight% or less.

16. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, further comprising at least one of carbon (C) 0.01 wt% or less (excluding 0 wt%), nitrogen (N) 0.01 wt% or less (excluding 0 wt%), titanium (Ti) 0.01 wt% or less (excluding 0 wt%), and phosphorus (P) 0.08 wt% or less (excluding 0 wt%).

17. In Paragraph 8, A method for manufacturing a non-oriented electrical steel sheet, further comprising Sn (tin) or Sb (antimony) in a range of 0.0001 weight% or more and 0.001 weight% or less.

18. In Paragraph 8, The steel sheet manufactured after the above cold rolling and annealing step has iron loss (W 10 / 400 A method for manufacturing non-oriented electrical steel sheets having a value of 12 W / kg or less.

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