Non-oriented electrical steel sheet and method for manufacturing same

Abstract

Provided in the present invention is a non-oriented electrical steel sheet comprising, in weight%, silicon (Si): 2.0 wt% to 3.8 wt%, aluminum (Al): 0.1 wt% to 1.3 wt%, manganese (Mn): 0.1 wt% to 0.5 wt%, carbon (C): 0 wt% (exclusive) to 0.003 wt%, sulfur (S): 0 wt% (exclusive) to 0.003 wt%, nitrogen (N): 0 wt% (exclusive) to 0.003 wt%, titanium (Ti): 0 wt% (exclusive) to 0.003 wt%, zirconium (Zr): 0 wt% (exclusive) to 0.003 wt%, niobium (Nb): 0 wt% (exclusive) to 0.003 wt%, phosphorus (P): 0.001 wt% to 0.015 wt%, copper (Cu): 0 wt% (exclusive) to 0.02 wt%, and the balance being iron (Fe) and inevitable impurities.

Description

Non-oriented electrical steel sheet and manufacturing method thereof

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

[0002] As environmental regulations have become increasingly stringent worldwide, the automobile industry is shifting from conventional internal combustion engines to eco-friendly vehicles (e.g., hybrids and electric vehicles). Unlike conventional fossil fuel-powered internal combustion engines, eco-friendly vehicles are powered by motors powered by batteries.

[0003] Drive motors for electric vehicles require improved magnetic properties of non-oriented electrical steel sheets used as motor core material to improve motor efficiency, and the development of drive motors for electric vehicles is accelerating as demand for electric vehicles increases.

[0004] Generally, electrical steel is divided into grain-oriented and non-oriented types. Grain-oriented electrical steel is primarily used for fixed components such as transformers. Non-oriented electrical steel, on the other hand, possesses consistent magnetic properties in all directions, regardless of rolling direction, making it primarily used in rotating automotive drive motors.

[0005] Non-oriented electrical steel sheets are easy to magnetize. <100> The directional aggregate structure must be uniformly generated throughout the plate, and for energy efficiency, core loss must be reduced and magnetic flux density increased. Here, core loss refers to the energy loss generated during the magnetization process, and magnetic flux density refers to the power that generates power.

[0006] Factors affecting the magnetic properties of non-oriented electrical steel include chemical composition, sheet thickness, microstructure, insulating coating, texture, and material shape. These diverse factors are influenced by the manufacturing process for non-oriented electrical steel. Non-oriented electrical steel is produced through a series of processes, including steelmaking / casting, hot rolling, hot pre-annealing, cold rolling, and heat treatment / coating. Optimizing these process conditions can produce electrical steel with superior magnetic properties.

[0007] Additionally, drive motors can be manufactured by stamping and laminating thin electrical steel sheets of 0.5 mm or less. The stamping properties of electrical steel sheets are a factor that affects the final performance of the drive motor. Burrs generated after stamping can result in shape defects, stress generation, and reduced insulation properties during lamination.

[0008] Embodiments of the present invention can provide a non-oriented electrical steel sheet having excellent punchability and a method for manufacturing the same by controlling the alloy composition of the non-oriented electrical steel sheet.

[0009] One embodiment of the present invention is a method for manufacturing a non-oriented electrical steel sheet, comprising, in wt%, silicon (Si): 2.0 wt% or more and 3.8 wt% or less, aluminum (Al): 0.1 wt% or more and 1.3 wt% or less, manganese (Mn): 0.1 wt% or more and 0.5 wt% or less, carbon (C): 0 to 0.003 wt% or less, sulfur (S): 0 to 0.003 wt% or less, nitrogen (N): 0 to 0.003 wt% or less, titanium (Ti): 0 to 0.003 wt% or less, zirconium (Zr): 0 to 0.003 wt% or less, niobium (Nb): 0 to 0.003 wt% or less, phosphorus (P): 0.001 wt% or more and 0.015 wt% or less, copper (Cu): 0 to 0.02 wt% or less, the remainder iron (Fe) and unavoidable impurities. A method for manufacturing a non-oriented electrical steel sheet is provided, comprising: a step of hot-rolling a slab to manufacture a hot-rolled sheet; a step of hot-rolling and annealing the manufactured hot-rolled sheet to manufacture a hot-rolled and annealed sheet; a step of cold-rolling the hot-rolled and annealed sheet to manufacture a cold-rolled sheet; and a step of cold-rolling and annealing the cold-rolled sheet to manufacture a cold-rolled and annealed sheet; wherein the contents of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the slab satisfy the following relational expression 1.

[0010] <Relationship 1>

[0011] 2.75≤log(5*[S]+21*[N]+11*[Ti]+12*[Zr]+18*[Nb]+6*[P]+11*[Cu])≤3.70

[0012] In the above relational expression 1, [S], [N], [Ti], [Zr], [Nb], [P], and [Cu] represent the contents (in ppm) of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the slab, respectively.

[0013] In this embodiment, when the non-oriented electrical steel sheet is punched, a shear surface, a fracture surface, and a burr may be formed in the non-oriented electrical steel sheet.

[0014] In this embodiment, the ratio of the shear surface can satisfy 45% or more and 100% or less, and the ratio of the fracture surface can satisfy 0% or more and 55% or less.

[0015] In this embodiment, the ratio of the length of the burr to the thickness of the non-oriented electrical steel sheet can be satisfied to be 3.5% or less.

[0016] In this embodiment, the contents of silicon (Si), manganese (Mn), and aluminum (Al) included in the slab can satisfy the following relationship 2.

[0017] <Relationship 2>

[0018] 1.55≤log(10.1169+(11.75*[Si]+6.2*[Mn]+8.76*[Al]))≤1.80

[0019] In the above relational expression 2, [Si], [Mn], and [Al] represent the contents (in weight%) of silicon (Si), manganese (Mn), and aluminum (Al) contained in the slab, respectively.

[0020] In this embodiment, the average grain size of the non-oriented electrical steel sheet may be 50 µm to 150 µm.

[0021] In this embodiment, the non-oriented electrical steel sheet has a core loss (W) of 3.0 W / kg or less. 15 / 50 (standard) can be used.

[0022] Another embodiment of the present invention is a non-oriented electrical steel sheet, which comprises, in wt%, silicon (Si): 2.0 wt% or more and 3.8 wt% or less, aluminum (Al): 0.1 wt% or more and 1.3 wt% or less, manganese (Mn): 0.1 wt% or more and 0.5 wt% or less, carbon (C): 0 to 0.003 wt% or less, sulfur (S): 0 to 0.003 wt% or less, nitrogen (N): 0 to 0.003 wt% or less, titanium (Ti): 0 to 0.003 wt% or less, zirconium (Zr): 0 to 0.003 wt% or less, niobium (Nb): 0 to 0.003 wt% or less, phosphorus (P): 0.001 wt% or more and 0.015 wt% or less, copper (Cu): 0 to 0.02 wt% or less, the remainder iron (Fe) and unavoidable impurities, and A non-oriented electrical steel sheet is provided in which the contents of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the non-oriented electrical steel sheet satisfy the following relational expression 3.

[0023] <Relationship 3>

[0024] 2.75≤log(5*[S]+21*[N]+11*[Ti]+12*[Zr]+18*[Nb]+6*[P]+11*[Cu])≤3.70

[0025] In the above relational expression 3, [S], [N], [Ti], [Zr], [Nb], [P], and [Cu] represent the contents (in ppm) of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the slab, respectively.

[0026] In this embodiment, when the non-oriented electrical steel sheet is punched, a shear surface, a fracture surface, and a burr may be formed in the non-oriented electrical steel sheet.

[0027] In this embodiment, the ratio of the shear surface can satisfy 45% or more and 100% or less, and the ratio of the fracture surface can satisfy 0% or more and 55% or less.

[0028] In this embodiment, the ratio of the length of the burr to the thickness of the non-oriented electrical steel sheet can be satisfied to be 3.5% or less.

[0029] In this embodiment, the contents of silicon (Si), manganese (Mn), and aluminum (Al) included in the non-oriented electrical steel sheet can satisfy the following relationship 4.

[0030] <Relationship 4>

[0031] 1.55≤log(10.1169+(11.75*[Si]+6.2*[Mn]+8.76*[Al]))≤1.80

[0032] In the above relational expression 4, [Si], [Mn], and [Al] represent the contents (in weight%) of silicon (Si), manganese (Mn), and aluminum (Al) contained in the slab, respectively.

[0033] In this embodiment, the average grain size of the non-oriented electrical steel sheet may be 50 µm to 150 µm.

[0034] In this embodiment, the non-oriented electrical steel sheet has a core loss (W) of 3.0 W / kg or less. 15 / 50 (standard) can be used.

[0035] According to one embodiment of the present invention, as described above, the alloy composition of a non-oriented electrical steel sheet can be controlled to improve punchability. Of course, the scope of the present invention is not limited by these effects.

[0036] FIG. 1 is a flowchart schematically illustrating a method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention.

[0037] FIG. 2 is a schematic drawing showing a cross-section of a non-oriented electrical steel sheet after a punching process is performed according to one embodiment of the present invention.

[0038] The present invention is capable of various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. The effects and features of the present invention, as well as the methods for achieving them, will become clearer with reference to the embodiments described in detail below, along with the drawings. However, the present invention is not limited to the embodiments disclosed below and can be implemented in various forms.

[0039] In the examples below, the terms first, second, etc. are not used in a limiting sense, but are used for the purpose of distinguishing one component from another.

[0040] In the examples below, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0041] In the following examples, terms such as “include” or “have” mean that a feature or component described in the specification is present, and do not preclude the possibility that one or more other features or components may be added.

[0042] For convenience of explanation, the sizes of components in the drawings may be exaggerated or reduced. For example, the sizes and thicknesses of each component shown in the drawings are arbitrarily shown for convenience of explanation, and the present invention is not necessarily limited to what is shown.

[0043] In some embodiments, where implementations are otherwise feasible, specific process sequences may be performed in a different order than described. For example, two processes described in succession may be performed substantially simultaneously, or in a reverse order from the described order.

[0044] In this specification, “A and / or B” refers to the case where it is A, or B, or both A and B. And, “at least one of A and B” refers to the case where it is A, or B, or both A and B.

[0045] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. When describing with reference to the drawings, identical or corresponding components are given the same drawing reference numerals, and redundant descriptions thereof will be omitted.

[0046] FIG. 1 is a flowchart schematically illustrating a method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention.

[0047] Referring to FIG. 1, a method for manufacturing a non-oriented electrical steel sheet may include a hot rolling step (S100), a hot rolling annealing step (S200), a slitting step (S300), a cold rolling step (S400), a cold rolling annealing step (S500), and a coating step (S600).

[0048] In a method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention, the semi-finished product subjected to hot rolling may be a slab. The slab in a semi-finished state can be obtained through a continuous casting process after obtaining molten steel of a predetermined composition through a steelmaking process.

[0049] First, slabs can be manufactured through a continuous casting process. Slabs may contain silicon (Si), aluminum (Al), manganese (Mn), carbon (C), sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), copper (Cu), the remainder iron (Fe), and unavoidable impurities.

[0050] Specifically, the slab may contain, in wt%, silicon (Si): 2.0 wt% or more and 3.8 wt% or less, aluminum (Al): 0.1 wt% or more and 1.3 wt% or less, manganese (Mn): 0.1 wt% or more and 0.5 wt% or less, carbon (C): 0 to 0.003 wt% or less, sulfur (S): 0 to 0.003 wt% or less, nitrogen (N): 0 to 0.003 wt% or less, titanium (Ti): 0 to 0.003 wt% or less, zirconium (Zr): 0 to 0.003 wt% or less, niobium (Nb): 0 to 0.003 wt% or less, phosphorus (P): 0.001 wt% or more and 0.015 wt% or less, copper (Cu): 0 to 0.02 wt% or less, the remainder iron (Fe) and unavoidable impurities.

[0051] Silicon (Si) can be a major additive element that increases the resistivity of manufactured non-oriented electrical steel sheets and reduces eddy current loss. Silicon (Si) can be included in an amount of 2.0 wt% or more and 3.8 wt% or less. If silicon (Si) is included in an amount less than 2.0 wt%, it may be difficult for the manufactured non-oriented electrical steel sheets to achieve the target core loss value. That is, if silicon (Si) is included in an amount less than 2.0 wt%, it may be difficult to achieve low core loss. On the other hand, as the silicon (Si) content increases, the permeability and magnetic flux density may decrease. If silicon (Si) is included in an amount exceeding 3.8 wt%, the magnetic flux density may decrease, the difficulty of the production process may increase, and the manufacturing cost may increase. In addition, if the silicon (Si) content exceeds 3.8 wt%, brittleness may increase, which may cause cracks and / or plate fracture during cold rolling.

[0052] Manganese (Mn) can increase the resistivity of non-oriented electrical steel sheets manufactured with silicon (Si) and improve the grain structure. Manganese (Mn) may be included in an amount of 0.1 wt% or more and 0.5 wt% or less. When manganese (Mn) is included in an amount less than 0.1 wt%, fine MnS precipitates may be formed, which may inhibit grain growth. On the other hand, when manganese (Mn) is included in an amount greater than 0.5 wt%, coarse MnS precipitates may be formed, which may deteriorate magnetic properties such as a decrease in magnetic flux density. In addition, when manganese (Mn) is included in an amount greater than 0.5 wt%, the iron loss reduction is small compared to the added amount, and cold rolling properties may deteriorate.

[0053] Aluminum (Al) can be a major additive element that increases the resistivity of non-oriented electrical steel sheets manufactured with silicon (Si) and thus reduces eddy current loss. Aluminum (Al) can be included in an amount of 0.1 wt% or more and 1.3 wt% or less. Aluminum (Al) induces AlN precipitation when combined with nitrogen. If aluminum (Al) is included in an amount exceeding 1.3 wt%, AlN may be formed, which may increase the iron loss of the manufactured non-oriented electrical steel sheet and inhibit grain growth. In addition, if aluminum (Al) is included in an amount exceeding 1.3 wt%, cold rolling properties may deteriorate, and magnetic flux density may decrease, resulting in poor magnetic properties.

[0054] Carbon (C) is a component that increases iron loss by forming carbides such as TiC and NbC, so the lower the carbon (C) content in the slab, the better. Carbon (C) may be included in an amount greater than 0 and less than or equal to 0.003 wt%. If carbon (C) is included in an amount greater than 0.003 wt%, self-aging may occur, which may deteriorate the magnetic properties of the manufactured non-oriented electrical steel sheet. If carbon (C) is included in an amount less than or equal to 0.003 wt%, the self-aging phenomenon may be suppressed. When the carbon (C) content is converted to ppm (parts per million), carbon (C) may be included in an amount greater than 0 and less than or equal to 30 ppm.

[0055] Phosphorus (P) can be a component that develops the grain structure as a grain boundary segregation element. Phosphorus (P) can be included in an amount of 0.001 wt% or more and 0.015 wt% or less. If phosphorus (P) is included in an amount exceeding 0.015 wt%, grain growth may be suppressed due to the segregation effect, magnetic properties may be deteriorated, and cold rolling properties may be reduced. When the phosphorus (P) content is converted to ppm, phosphorus (P) can be included in an amount of 10 ppm or more and 150 ppm or less.

[0056] Sulfur (S) may be a component that increases iron loss and inhibits grain growth by forming precipitates such as MnS and CuS. Therefore, it may be desirable to have a low sulfur (S) content in the slab. Sulfur (S) may be included in an amount greater than 0 and less than or equal to 0.003 wt%. When sulfur (S) is included in an amount greater than 0.003 wt%, precipitates such as MnS and CuS may be formed, increasing iron loss and inhibiting grain growth. When the sulfur (S) content is converted to ppm, sulfur (S) may be included in an amount greater than 0 and less than or equal to 30 ppm.

[0057] Nitrogen (N) can form precipitates such as AlN, TiN, and NbN, thereby increasing iron loss and inhibiting grain growth. Therefore, it may be desirable to have a low nitrogen (N) content in the slab. Nitrogen (N) may be included in an amount greater than 0 and less than or equal to 0.003 wt%. When nitrogen (N) is included in an amount greater than 0.003 wt%, precipitates such as AlN, TiN, and NbN may be formed, thereby increasing iron loss and inhibiting grain growth. When the nitrogen (N) content is converted to ppm, nitrogen (N) may be included in an amount greater than 0 and less than or equal to 30 ppm.

[0058] Titanium (Ti) can suppress grain growth by forming fine precipitates such as TiC and TiN. As the magnetic properties deteriorate as titanium (Ti) is added, it may be desirable to add as little titanium (Ti) as possible. Titanium (Ti) may be included in an amount greater than 0 and less than or equal to 0.003 wt%. When titanium (Ti) is included in an amount greater than 0.003 wt%, fine precipitates such as TiC and TiN may be formed, suppressing grain growth and resulting in poor magnetic properties. When the titanium (Ti) content is converted to ppm, titanium (Ti) may be included in an amount greater than 0 and less than or equal to 30 ppm.

[0059] Zirconium (Zr) reacts with carbon and nitrogen to form fine precipitates and inhibit grain growth. Since increasing the amount of zirconium (Zr) results in poorer grain structure formation, zirconium (Zr) may be included in amounts exceeding 0 and not exceeding 0.003 wt%. When the zirconium (Zr) content is converted to ppm, zirconium (Zr) may be included in amounts exceeding 0 ppm and not exceeding 30 ppm.

[0060] Niobium (Nb) can form fine precipitates such as NbC, inhibiting grain growth and developing a structure unfavorable for magnetism. Niobium (Nb) may be included in an amount greater than 0 and less than or equal to 0.003 wt%. When niobium (Nb) is included in an amount greater than 0.003 wt%, it may form fine precipitates such as NbC, inhibiting grain growth and resulting in poor magnetic properties. When the content of niobium (Nb) is converted to ppm, niobium (Nb) may be included in an amount greater than 0 and less than or equal to 30 ppm.

[0061] Copper (Cu) can form sulfides with manganese. Furthermore, the formed precipitates can inhibit grain growth. Copper (Cu) may be present in an amount greater than 0 and less than or equal to 0.02 wt%. If copper (Cu) is present in an amount greater than 0.02 wt%, high-temperature embrittlement may occur, resulting in cracks during rolling or hot rolling. When the copper (Cu) content is converted to ppm, copper (Cu) may be present in an amount greater than 0 and less than or equal to 200 ppm.

[0062] In one embodiment, the contents of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) included in the slab may satisfy the following relationship 1.

[0063] <Relationship 1>

[0064] 2.75≤log(5*[S]+21*[N]+11*[Ti]+12*[Zr]+18*[Nb]+6*[P]+11*[Cu])≤3.70

[0065] In equation 1, [S], [N], [Ti], [Zr], [Nb], [P], and [Cu] represent the contents (in ppm) of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the slab, respectively. For example, if the content of sulfur (S) contained in the slab is 5 ppm, [S] may be 5.

[0066] If the value of relational expression 1 is less than 2.75, the ratio of the length of the burr to the thickness of the non-oriented electrical steel sheet may exceed 3.5%, which may cause shape defects, stress generation, and reduced insulation properties when the non-oriented electrical steel sheet is laminated. In addition, if the value of relational expression 1 exceeds 3.70, the fracture surface ratio may exceed 55%, which may cause cracks.

[0067] Therefore, when the contents (in ppm) of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the slab satisfy Equation 1, the ratio of the length of the burr to the thickness of the non-oriented electrical steel sheet formed during punching can be formed to be 3.5% or less, and the occurrence of cracks can be prevented or minimized. This will be explained in more detail below.

[0068] In one embodiment, the contents of silicon (Si), manganese (Mn), and aluminum (Al) included in the slab may satisfy the following relationship 2.

[0069] <Relationship 2>

[0070] 1.55≤log(10.1169+(11.75*[Si]+6.2*[Mn]+8.76*[Al]))≤1.80

[0071] In equation 2, [Si], [Mn], and [Al] represent the contents (in wt%) of silicon (Si), manganese (Mn), and aluminum (Al) contained in the slab, respectively. For example, if the content of silicon (Si) contained in the slab is 2.0 wt%, [Si] may be 2.0.

[0072] When the value of relational expression 2 is less than 1.55, the core loss of the manufactured non-oriented electrical steel sheet may exceed 3.0 W / kg. On the other hand, when the value of relational expression 2 exceeds 1.80, the core loss is excellent, but the cold-rollability is deteriorated, which may cause cracks or plate breakage. Therefore, when the value of relational expression 2 satisfies 1.55 or more and 1.80 or less, the manufactured non-oriented electrical steel sheet may have a core loss of 3.0 W / kg or less, and cracks and / or plate breakage in the steel sheet during cold rolling may be prevented or minimized. This will be described in more detail below.

[0073] In the hot rolling step (S100), the slab is reheated and then hot rolled to produce a hot-rolled sheet. For example, a steel sheet that has undergone the hot rolling step (S100) may be called a hot-rolled sheet.

[0074] First, the hot rolling step (S100) can reheat the slab. The slab reheating temperature can be 1,000℃ or higher and 1,250℃ or lower. If the slab reheating temperature is lower than 1,000℃, the rolling load may increase during hot rolling (e.g., rough rolling and / or finish rolling), which may reduce the rollability. On the other hand, if the slab reheating temperature exceeds 1,250℃, precipitates such as C, S, and N in the slab may be re-dissolved, forming fine precipitates during subsequent rolling and annealing steps, which may inhibit grain growth and deteriorate magnetic properties.

[0075] The hot rolling step (S100) can roll the slab at a predetermined finishing rolling temperature. At this time, the finishing rolling temperature can be 850°C or higher and 950°C or lower.

[0076] Additionally, the hot rolling step (S100) can cool and coil the hot-rolled steel plate to a predetermined coiling temperature (Coiling Temperature: CT). At this time, the coiling temperature can be 550°C or higher and 680°C or lower.

[0077] The thickness of the hot-rolled sheet manufactured through the hot rolling step (S100) may be 1.8 mm or more and 2.6 mm or less. In this case, if the thickness of the hot-rolled sheet exceeds 2.6 mm, the cold rolling reduction ratio increases, which may result in a deterioration of the texture.

[0078] A hot-rolling annealing step (S200) may be performed after the hot-rolling step (S100). In the hot-rolling annealing step (S200), a hot-rolled hot-rolled sheet may be annealed to produce a hot-rolled annealed sheet. For example, a steel sheet that has undergone the hot-rolling annealing step (S200) may be referred to as a hot-rolled annealed sheet.

[0079] In the hot-rolling annealing step (S200), the hot-rolled sheet may be heated to a hot-rolling annealing temperature at a heating rate (or heating rate) of 20°C / s or more, annealed at the hot-rolling annealing temperature for 30 s to 150 s, and then cooled at a cooling rate of 20°C / s or more. At this time, the hot-rolling annealing temperature may be 950°C or more and 1,100°C or less. If the hot-rolling annealing temperature is less than 950°C, grain growth may not be sufficient, resulting in the formation of fine grains, which may deteriorate the magnetism of the manufactured non-oriented electrical steel sheet. In addition, if the hot-rolling annealing temperature is less than 950°C, fine inclusions such as carbides and nitrides may be formed from the surface layer, and the inclusions may not grow sufficiently, which may deteriorate the magnetism of the manufactured non-oriented electrical steel sheet. On the other hand, if the hot-rolled annealing temperature exceeds 1,100℃, the grains may grow excessively, which may increase the grain size deviation and cause a lot of oxidation, which may have a negative effect on the manufactured non-oriented electrical steel sheet.

[0080] A slitting step (S300) may be performed after the hot-rolled annealing step (S200). In the slitting step (S300), a coiled steel plate (e.g., a hot-rolled and annealed plate or a hot-rolled plate) is uncoiled, and then the steel plate (e.g., a hot-rolled and annealed plate or a hot-rolled plate) is cut using a knife or the like, and then the cut steel plate (e.g., a hot-rolled and annealed plate or a hot-rolled plate) is wound into a coil.

[0081] In one embodiment, in the slitting step (S300), a steel plate (e.g., a hot-rolled and annealed plate or a hot-rolled plate) may be cut using a knife or the like. For example, in the slitting step (S300), the steel plate (e.g., a hot-rolled and annealed plate or a hot-rolled plate) may be divided into three parts in the width direction, or the steel plate (e.g., a hot-rolled and annealed plate or a hot-rolled plate) may be divided into four parts in the width direction. Alternatively, in the slitting step (S300), both edge portions of the steel plate (e.g., a hot-rolled and annealed plate or a hot-rolled plate) may be slit.

[0082] After the slitting step (S300), a cold rolling step (S400) may be performed. In the cold rolling step (S400), the slit hot-rolled and annealed sheet may be cold rolled to produce a cold-rolled sheet. For example, a steel sheet that has undergone the cold rolling step (S400) may be referred to as a cold-rolled sheet.

[0083] The oxide layer formed on the surface of the hot-rolled and annealed plate can be removed using a pickling solution before the cold rolling step (S400).

[0084] In the cold rolling step (S400), the hot-rolled and annealed plate can be cold rolled to a thickness of 0.5 mm or less. At this time, in order to impart rollability, the plate temperature can be increased to 150°C or more and 200°C or less to perform warm rolling. The reduction ratio in the cold rolling step (S400) can be 50% or more. Preferably, the final reduction ratio in the cold rolling step (S400) can be 70% or more and 95% or less.

[0085] After the cold rolling step (S400), a cold rolling annealing step (S500) may be performed. In the cold rolling annealing step (S500), a cold-rolled cold-rolled sheet may be annealed to produce a cold-rolled annealed sheet. For example, a steel sheet that has undergone the cold rolling annealing step (S500) may be referred to as a cold-rolled annealed sheet.

[0086] In the cold rolling annealing step (S500), the cold rolled sheet is heated to a cold rolling annealing temperature (e.g., target temperature) at a heating rate (or heating rate) of 5°C / s or more and 30°C / s or less, and then annealed at the cold rolling annealing temperature for 40 s or more and 300 s or more, and then cooled at a cooling rate of 20°C / s or more. At this time, the cold rolling annealing temperature may be 800°C or more and 1,100°C or less. When the cold rolling annealing temperature is less than 800°C, the grain size may be fine, which may increase the hysteresis loss. On the other hand, when the cold rolling annealing temperature is more than 1,100°C, the grain size may be coarse, which may increase the eddy current loss.

[0087] The cold rolling annealing step (S500) can be performed under mixed atmosphere conditions to prevent surface oxidation and nitriding. For example, a mixed atmosphere of nitrogen and hydrogen can be used to further smooth the surface.

[0088] A coating step (S600) may be performed after the cold-rolled annealing step (S500). In the coating step (S600), a coating layer may be formed on the cold-rolled annealed sheet. By forming the coating layer through the coating step (S600), the punchability can be improved and insulation can be secured.

[0089] In one embodiment, a non-oriented electrical steel sheet can be manufactured through a hot rolling step (S100) to a coating step (S600).

[0090] A non-oriented electrical steel sheet according to one embodiment of the present invention may include silicon (Si), aluminum (Al), manganese (Mn), carbon (C), sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), copper (Cu), the remainder iron (Fe) and unavoidable impurities.

[0091] Specifically, the non-oriented electrical steel sheet may contain, in wt%, silicon (Si): 2.0 wt% or more and 3.8 wt% or less, aluminum (Al): 0.1 wt% or more and 1.3 wt% or less, manganese (Mn): 0.1 wt% or more and 0.5 wt% or less, carbon (C): 0 to 0.003 wt% or less, sulfur (S): 0 to 0.003 wt% or less, nitrogen (N): 0 to 0.003 wt% or less, titanium (Ti): 0 to 0.003 wt% or less, zirconium (Zr): 0 to 0.003 wt% or less, niobium (Nb): 0 to 0.003 wt% or less, phosphorus (P): 0.001 wt% or more and 0.015 wt% or less, copper (Cu): 0 to 0.02 wt% or less, the remainder iron (Fe) and unavoidable impurities.

[0092] The average grain size of the non-oriented electrical steel sheet manufactured through the method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention may be 50 ㎛ or more and 150 ㎛ or less. In addition, the non-oriented electrical steel sheet manufactured through the method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention may have a core loss (W) of 3.0 W / kg or less. 15 / 50 can have a magnetic flux density (B) of 1.60 T or more. 50 In addition, the non-oriented electrical steel sheet manufactured through the method for manufacturing a non-oriented electrical steel sheet according to one embodiment of the present invention may have a yield strength (YP) of 200 MPa or more and a tensile strength (TS) of 350 MPa or more.

[0093] FIG. 2 is a schematic drawing showing a cross-section of a non-oriented electrical steel sheet after a punching process is performed according to one embodiment of the present invention.

[0094] Referring to FIG. 2, when a punching process is performed on a non-oriented electrical steel sheet (100) according to one embodiment of the present invention, a shear surface (110), a fracture surface (120), and a burr (130) may be formed on the non-oriented electrical steel sheet (100).

[0095] In one embodiment, the shear surface (110) may be a surface extending in the thickness direction of the non-oriented electrical steel sheet (100) or at a predetermined angle with the thickness direction. The shear surface (110) may have a smooth surface. Alternatively, the shear surface (110) may be formed in a straight line within the thickness range of the material when analyzing the side surface of the material after punching, and may have less roughness when observed from the front.

[0096] In one embodiment, the fracture surface (120) may be a surface formed when the non-oriented electrical steel sheet (100) is fractured. The fracture surface (120) may be irregular compared to the shear surface (110). The fracture surface (120) may have an irregular surface. Alternatively, the fracture surface (120) may be formed in a diagonal shape within the thickness range of the material when analyzing the side of the material after punching, and may have a rough surface when observed from the front.

[0097] In one embodiment, a burr (130) may be formed on the non-oriented electrical steel sheet (100) during a punching process of the non-oriented electrical steel sheet (100). Alternatively, the burr (130) may refer to a portion formed outside the thickness range of the material when analyzing the side surface of the material after punching.

[0098] Additionally, in one embodiment, a roll over may be formed in the non-oriented electrical steel sheet (100). The compressive stress generated during punching may cause plastic deformation of the material as the punching progresses, and the plastic deformation of the material may cause the material to bend and be pressed, thereby forming a roll over. The roll over may be affected by the material quality or clearance conditions of the material.

[0099] In one embodiment, the shear section ratio (%) may be 45% or more and 100% or less (or, 45% or more and less than 100%). At this time, the shear section ratio (%) may be calculated as L1 / TH*100. At this time, TH may be the thickness of the non-oriented electrical steel sheet (100), and L1 may be the length of the shear section (110) in the thickness direction of the non-oriented electrical steel sheet (100). That is, the shear section ratio (%) may mean the ratio of the thickness of the non-oriented electrical steel sheet (100) to the shear section (110). In addition, the thickness (TH) of the non-oriented electrical steel sheet (100) and the length (L1) of the shear section (110) in the thickness direction of the non-oriented electrical steel sheet (100) may be measured using an optical microscope (OM, Optical Microscopy).

[0100] In one embodiment, the fracture surface ratio (%) may be 0% or more and 55% or less (or, more than 0% and 55% or less). At this time, the fracture surface ratio (%) may be calculated as L2 / TH*100. At this time, TH may be the thickness of the non-oriented electrical steel sheet (100), and L2 may be the length of the fracture surface (120) in the thickness direction of the non-oriented electrical steel sheet (100). That is, the fracture surface ratio (%) may mean the ratio of the thickness of the non-oriented electrical steel sheet (100) to the fracture surface (120). In addition, the thickness (TH) of the non-oriented electrical steel sheet (100) and the length (L2) of the fracture surface (120) in the thickness direction of the non-oriented electrical steel sheet (100) may be measured using an optical microscope (OM). When the fracture surface ratio (%) exceeds 55%, the magnetic properties may be deteriorated. In addition, if the fracture surface ratio (%) exceeds 55%, residual stress increases and it may be difficult to form a sound laminated surface during lamination.

[0101] In one embodiment, the ratio of the length of the burr (130) to the thickness of the non-oriented electrical steel sheet (100) may be 3.5% or less. At this time, the ratio of the length of the burr (130) to the thickness (TH) of the non-oriented electrical steel sheet (100) may be calculated as L3 / TH*100. At this time, L3 may be the length of the burr (130) in the thickness direction of the non-oriented electrical steel sheet (100), and TH may be the thickness of the oriented electrical steel sheet (100) in the thickness direction of the non-oriented electrical steel sheet (100). When the ratio of the length (L3) of the burr (130) to the thickness (TH) of the non-oriented electrical steel sheet (100) exceeds 3.5%, shape defects, stress generation, and reduced insulation properties may occur when the non-oriented electrical steel sheet (100) is laminated.

[0102] In one embodiment, the contents of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) included in the non-oriented electrical steel sheet may satisfy the following relationship 3.

[0103] <Relationship 3>

[0104] 2.75≤log(5*[S]+21*[N]+11*[Ti]+12*[Zr]+18*[Nb]+6*[P]+11*[Cu]) ≤ 3.70

[0105] In equation 3, [S], [N], [Ti], [Zr], [Nb], [P], and [Cu] represent the contents (in ppm) of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the non-oriented electrical steel sheet, respectively. For example, when the content of sulfur (S) contained in the non-oriented electrical steel sheet is 5 ppm, [S] may be 5.

[0106] When the value of relational expression 3 is less than 2.75, the length of the burr formed during the punching process increases, which may cause shape defects, stress generation, and reduced insulation properties when laminating non-oriented electrical steel sheets. Specifically, when the value of relational expression 3 is less than 2.75, the ratio of the length (L3) of the burr (130) to the thickness (TH) of the non-oriented electrical steel sheet (100) is formed to exceed 3.5%, which may cause shape defects, stress generation, and reduced insulation properties when laminating non-oriented electrical steel sheets. In addition, when the value of relational expression 1 exceeds 3.70, the fracture surface ratio may exceed 55%, which may cause cracks.

[0107] Accordingly, when the contents (in ppm) of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the slab satisfy the relational expression 1, the ratio of the length (L3) of the burr (130) to the thickness (TH) of the non-oriented electrical steel sheet (100) is formed to be 3.5% or less, so that shape defects, stress generation, and reduction in insulation properties during lamination of the non-oriented electrical steel sheet (100) can be prevented or minimized, and cracks can be prevented or minimized. This will be described in more detail below.

[0108] In one embodiment, the contents of silicon (Si), manganese (Mn), and aluminum (Al) included in the non-oriented electrical steel sheet may satisfy the following relationship 4.

[0109] <Relationship 4>

[0110] 1.55≤log(10.1169+(11.75*[Si]+6.2*[Mn]+8.76*[Al]))≤1.80

[0111] In Equation 4, [Si], [Mn], and [Al] represent the contents (in wt%) of silicon (Si), manganese (Mn), and aluminum (Al) contained in the non-oriented electrical steel sheet, respectively. For example, when the content of silicon (Si) contained in the non-oriented electrical steel sheet is 2.0 wt%, [Si] may be 2.0.

[0112] When the value of relational expression 2 is less than 1.55, the iron loss of the non-oriented electrical steel sheet (100) may exceed 3.0 W / kg. On the other hand, when the value of relational expression 2 is more than 1.80, the iron loss is excellent, but the cold rolling property is reduced, which may cause cracks or plate breakage. Therefore, when the value of relational expression 2 satisfies 1.55 or more and 1.80 or less, the non-oriented electrical steel sheet (100) may have an iron loss of 3.0 W / kg or less, and cracks and / or plate breakage in the steel sheet during cold rolling may be prevented or minimized. This will be described in more detail below.

[0113] Experimental example

[0114] Below, the present invention will be described in more detail through experimental examples. However, the following experimental examples are intended to further illustrate the present invention, and the scope of the present invention is not limited by these examples. Those skilled in the art may appropriately modify or alter the following experimental examples within the scope of the present invention.

[0115] Classification Component (% by weight) (ppm) SiAlMnCSNTiZrNbPCuExample 12.00.240.14192112881670100Example 22.350.520.231220188786545Example 32.620.620.412024121012144630Example 42.800.560.2114111916131112040Example 53.170.800.45251042015187041Example 63.440.58 0.292418111020155070Comparison Example 11.820.220.2510121555105060Comparison Example 22.00.260.185555551010Comparison Example 32.810.520.204353441516Comparison Example 42.650.580.43353638362835160170Comparison Example 52.820.570.21323733313631160190Comparison Example 63.920.720.42121819925166872

[0116] Hot rolling step Slab reheating temperature (℃) 1,200℃ Finish rolling temperature (℃) 900℃ Coiling temperature (℃) 600℃ Hot rolling thickness (mm) 2.3mm Hot rolling annealing step Heating speed (℃ / s) 20℃ / s Annealing temperature (℃) 1,000℃ Holding time (s) 60s Cooling speed (℃ / s) 20℃ / s Cold rolling step Reduction ratio (%) 0.27mm 88.3% 0.30mm 87% 0.35mm 84.8% 0.50mm 78.3% Cold rolling annealing step Heating speed (℃ / s) 20℃ / s Annealing temperature (℃) 950℃ Holding time (s) 60s Cooling speed (℃ / s) 20℃ / s

[0117] Thickness (mm) Value of equation 1 Ratio of length of burr to thickness (%) Ratio of fracture area (%) Value of equation 2 Iron loss (W 15 / 50, W / kg)Example 10.503.371.2254.71.562.93Example 20.503.231.8150.81.632.82Example 30.503.172.0647.91.682.75Example 40.353.331.3953.71.682.31Example 50.303.241.7751.31.752.08Example 60.273.301.5154.21.75 1.88Comparative Example 10.503.211.8949.81.543.12Comparative Example 20.502.704.224.81.572.87Comparative Example 30.352.734.026.31.682.24Comparative Example 40.503.710.1273.91.692.81Comparative Example 50.353.720.1174.81.692.36Comparative Example 60.353.381.7858.21.811.62

[0118] Examples 1 to 6 and Comparative Examples 1 to 6 are samples manufactured using slabs composed of the components shown in Table 1, the remainder iron (Fe), and unavoidable impurities, under the process conditions shown in Table 2. At this time, all samples were manufactured to the same size of 80 mm in width and 150 mm in length.

[0119] Examples 1 to 6 and Comparative Examples 1 to 6 were manufactured under the same process conditions, but with different component contents.

[0120] At this time, the side and front surfaces of the samples were observed at a magnification of 100 to 300 times using an optical microscope (OM, Optical Microscopy) to measure the thickness of the samples (e.g., non-oriented electrical steel sheet), the length of the cross-section, the length of the fracture surface, and the length of the burr.

[0121] In Table 3, the value of relation 1 corresponds to the value of log(5*[S]+21*[N]+11*[Ti]+12*[Zr]+18*[Nb]+6*[P]+11*[Cu]), and the value of relation 2 corresponds to the value of log(10.1169+(11.75*[Si]+6.2*[Mn]+8.76*[Al])).

[0122] Referring to Examples 1 to 6, it can be confirmed that the value of relational expression 1 satisfies 2.75 or more and 3.70 or less, and the value of relational expression 2 satisfies 1.55 or more and 1.80 or less. In addition, when the value of relational expression 1 satisfies 2.75 or more and 3.70 or less, it can be confirmed that the ratio of the burr length to the thickness of the non-oriented electrical steel sheet (or sample) satisfies 3.5% or less, and the fracture surface ratio (%) satisfies 0% or more and 55% or less (or, more than 0 and 55% or less). In addition, when the value of relational expression 2 satisfies 1.55 or more and 1.80 or less, it can be confirmed that the core loss is 3.0 W / kg or less.

[0123] Comparative Example 1 is a case where the value of relational expression 2 is less than 1.55, and it can be confirmed that the iron loss of Comparative Example 1 exceeds 3.0 W / kg. Therefore, when the value of relational expression 2 is less than 1.55, the iron loss of the manufactured non-oriented electrical steel sheet may exceed 3.0 W / kg.

[0124] Comparative Example 2 is a case where the value of Relationship 1 is less than 2.75, and it can be confirmed that Comparative Example 2 has a ratio of the length of the burr to the thickness of the non-oriented electrical steel sheet exceeding 3.5%. In this case, when the ratio of the length of the burr to the thickness of the non-oriented electrical steel sheet exceeds 3.5%, shape defects, stress generation, and reduced insulation properties may occur when laminating the non-oriented electrical steel sheet.

[0125] Comparative Example 3 is a case where the value of Relationship 1 is less than 2.75, and it can be confirmed that Comparative Example 3 has a ratio of the length of the burr to the thickness of the non-oriented electrical steel sheet exceeding 3.5%. In this case, when the ratio of the length of the burr to the thickness exceeds 3.5%, shape defects, stress generation, and reduced insulation properties may occur when laminating the non-oriented electrical steel sheet.

[0126] Comparative Examples 4 and 5 are cases where the value of relational expression 1 exceeds 3.70, and it can be confirmed that Comparative Examples 4 and 5 have a fracture ratio (%) of 73.9% and 74.8%, respectively. When the fracture ratio (%) exceeds 55%, cracks may occur.

[0127] Comparative Example 6 is a case where the value of relational expression 2 exceeds 1.80. When the value of relational expression 2 exceeds 1.80, the iron loss satisfies 3.0 W / kg, but the cold rolling property decreases, which may cause plate breakage and / or cracking.

[0128] While the present invention has been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and those skilled in the art will appreciate that various modifications and equivalent alternative embodiments are possible. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the appended claims.

Claims

1. A method for manufacturing a non-oriented electrical steel sheet, A step of manufacturing a hot-rolled sheet by hot-rolling a slab including, in wt%, silicon (Si): 2.0 wt% or more and 3.8 wt% or less, aluminum (Al): 0.1 wt% or more and 1.3 wt% or less, manganese (Mn): 0.1 wt% or more and 0.5 wt% or less, carbon (C): 0 to 0.003 wt% or less, sulfur (S): 0 to 0.003 wt% or less, nitrogen (N): 0 to 0.003 wt% or less, titanium (Ti): 0 to 0.003 wt% or less, zirconium (Zr): 0 to 0.003 wt% or less, niobium (Nb): 0 to 0.003 wt% or less, phosphorus (P): 0.001 wt% or more and 0.015 wt% or less, copper (Cu): 0 to 0.02 wt% or less, the remainder iron (Fe) and unavoidable impurities; A step of manufacturing a hot-rolled and annealed plate by hot-rolling and annealing the hot-rolled plate manufactured above; A step of manufacturing a cold-rolled sheet by cold rolling the hot-rolled and annealed sheet; and A step of manufacturing a cold-rolled annealed plate by cold-rolling and annealing the above cold-rolled plate; Including, A method for manufacturing a non-oriented electrical steel sheet, wherein the contents of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the above slab satisfy the following relational expression 1. <Relationship 1> 2.75≤log(5*[S]+21*[N]+11*[Ti]+12*[Zr]+18*[Nb]+6*[P]+11*[Cu])≤3.70 In the above relational expression 1, [S], [N], [Ti], [Zr], [Nb], [P], and [Cu] represent the contents (in ppm) of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the slab, respectively.

2. In paragraph 1, A method for manufacturing a non-oriented electrical steel sheet, wherein when the non-oriented electrical steel sheet is punched, a shear plane, a fracture plane, and a burr are formed on the non-oriented electrical steel sheet.

3. In paragraph 2, A method for manufacturing a non-oriented electrical steel sheet, wherein the ratio of the above cross-section satisfies 45% or more and 100% or less, and the ratio of the above fracture surface satisfies 0% or more and 55% or less.

4. In paragraph 2, A method for manufacturing a non-oriented electrical steel sheet, wherein the ratio of the length of the burr to the thickness of the non-oriented electrical steel sheet is 3.5% or less.

5. In paragraph 1, A method for manufacturing a non-oriented electrical steel sheet, wherein the contents of silicon (Si), manganese (Mn), and aluminum (Al) contained in the above slab satisfy the following relationship 2. <Relationship 2> 1.55≤log(10.1169+(11.75*[Si]+6.2*[Mn]+8.76*[Al]))≤1.80 In the above relational expression 2, [Si], [Mn], and [Al] represent the contents (in weight%) of silicon (Si), manganese (Mn), and aluminum (Al) contained in the slab, respectively.

6. In paragraph 1, A method for manufacturing a non-oriented electrical steel sheet, wherein the average grain size of the non-oriented electrical steel sheet is 50 ㎛ to 150 ㎛.

7. In paragraph 1, The above non-oriented electrical steel sheet has a core loss (W) of 3.0 W / kg or less. 15 / 50 A method for manufacturing a non-oriented electrical steel sheet having a standard.

8. As a non-oriented electrical steel sheet, In weight%, silicon (Si): 2.0 wt% or more and 3.8 wt% or less, aluminum (Al): 0.1 wt% or more and 1.3 wt% or less, manganese (Mn): 0.1 wt% or more and 0.5 wt% or less, carbon (C): 0 to 0.003 wt% or less, sulfur (S): 0 to 0.003 wt% or less, nitrogen (N): 0 to 0.003 wt% or less, titanium (Ti): 0 to 0.003 wt% or less, zirconium (Zr): 0 to 0.003 wt% or less, niobium (Nb): 0 to 0.003 wt% or less, phosphorus (P): 0.001 wt% or more and 0.015 wt% or less, copper (Cu): 0 to 0.02 wt% or less, the remainder iron (Fe) and unavoidable impurities, A non-oriented electrical steel sheet having a content of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the above non-oriented electrical steel sheet, which satisfies the following relational expression 3. <Relationship 3> 2.75≤log(5*[S]+21*[N]+11*[Ti]+12*[Zr]+18*[Nb]+6*[P]+11*[Cu])≤3.70 In the above relational expression 3, [S], [N], [Ti], [Zr], [Nb], [P], and [Cu] represent the contents (in ppm) of sulfur (S), nitrogen (N), titanium (Ti), zirconium (Zr), niobium (Nb), phosphorus (P), and copper (Cu) contained in the slab, respectively.

9. In paragraph 8, A non-oriented electrical steel sheet, wherein when the non-oriented electrical steel sheet is punched, a shear plane, a fracture plane, and a burr are formed on the non-oriented electrical steel sheet.

10. In paragraph 9, A non-oriented electrical steel sheet, wherein the above cross-sectional ratio satisfies 45% or more and 100% or less, and the above fracture surface ratio satisfies 0% or more and 55% or less.

11. In paragraph 9, A non-oriented electrical steel sheet having a ratio of burr length to thickness of the non-oriented electrical steel sheet of 3.5% or less.

12. In paragraph 8, A non-oriented electrical steel sheet having a content of silicon (Si), manganese (Mn), and aluminum (Al) contained in the non-oriented electrical steel sheet that satisfies the following relational expression 4. <Relationship 4> 1.55≤log(10.1169+(11.75*[Si]+6.2*[Mn]+8.76*[Al]))≤1.80 In the above relational expression 4, [Si], [Mn], and [Al] represent the contents (in weight%) of silicon (Si), manganese (Mn), and aluminum (Al) contained in the slab, respectively.

13. In paragraph 8, A non-oriented electrical steel sheet having an average grain size of 50 ㎛ to 150 ㎛.

14. In paragraph 8, The above non-oriented electrical steel sheet has a core loss (W) of 3.0 W / kg or less. 15 / 50 Non-oriented electrical steel sheet having a standard).

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