Non-oriented electrical steel sheet and method for manufacturing same

Abstract

The present invention relates to a method for manufacturing a non-oriented electrical steel sheet and provides a method for manufacturing a non-oriented electrical steel sheet, the method comprising: a hot rolling step of hot-rolling a slab to produce a hot-rolled sheet, the slab comprising, by weight%, silicon (Si): 1.8 wt% to 2.8 wt%, manganese (Mn): 0.1 wt% to 0.5 wt%, aluminum (Al): 0.1 wt% to 0.7 wt%, sulfur (S): 0 wt% (exclusive) to 0.003 wt% (inclusive), and a total of at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y): 0.0005 wt% to 0.0034 wt%, with the balance being iron (Fe) and inevitable impurities; a preliminary annealing step of annealing the hot-rolled sheet; a cold rolling step of cold-rolling the preliminarily annealed hot-rolled sheet to produce a cold-rolled sheet; and a cold rolling annealing step of cold annealing the cold-rolled sheet.

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] There are various directions in research to improve the magnetic properties of existing non-oriented electrical steel sheets, but in terms of component control, there is a tendency to remain limited to the level of adding elements such as tin (Sn) and antimony (Sb) to the basic components such as silicon (Si), aluminum (Al), and manganese (Mn).

[0007] However, in order to develop electrical steel sheets with higher-performance magnetic properties, research on various elements is necessary.

[0008] Embodiments of the present invention can provide a non-oriented electrical steel sheet with improved magnetic properties by controlling the alloy composition of the non-oriented electrical steel sheet and a method for manufacturing the same.

[0009] One embodiment of the present invention is a method for manufacturing a non-oriented electrical steel sheet, comprising: a hot rolling step of hot-rolling a slab including, in wt%, silicon (Si): 1.8 wt% to 2.8 wt%, manganese (Mn): 0.1 wt% to 0.5 wt%, aluminum (Al): 0.1 wt% to 0.7 wt%, sulfur (S): more than 0 wt% and 0.003 wt% or less, a total of at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y): 0.0005 wt% to 0.0034 wt%, the remainder iron (Fe) and unavoidable impurities, to manufacture a hot-rolled sheet; a preliminary annealing step of preliminarily annealing the hot-rolled sheet; a cold rolling step of cold-rolling the preliminarily annealed hot-rolled sheet to manufacture a cold-rolled sheet; A method for manufacturing a non-oriented electrical steel sheet is provided, including a cold rolling annealing step of cold rolling the cold rolled sheet.

[0010] In this embodiment, the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among all sulfide inclusions can satisfy the following relationship 1.

[0011] <Relationship 1>

[0012] A / B * 100 ≤ 20%

[0013] In the above relational expression 1, A may be the number of sulfide inclusions having a diameter of 10 nm to 100 nm, and B may be the total number of sulfide inclusions.

[0014] In this embodiment, the aggregate structure of the non-oriented electrical steel sheet {110} <110> The orientation function can be 3 to 5.

[0015] In the present embodiment, the sum of the contents of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y), the ratio of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions, and the aggregate structure {110} of the non-oriented electrical steel sheet <110> The orientation function can satisfy the following relationship 2.

[0016] <Relationship 2>

[0017]

[0018] In the above relational expression 2, L is the sum of the contents of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y), S is the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions, and T is the {110} texture of the non-oriented electrical steel sheet. <110> may be a defense function.

[0019] In this embodiment, the non-oriented electrical steel sheet has a core loss (W) of less than 3.28 W / kg. 15 / 50 (standard) can be used.

[0020] In this embodiment, the non-oriented electrical steel sheet has a magnetic flux density (B) of 1.69 T or more. 50 (standard) can be used.

[0021] In this embodiment, the average grain size of the non-oriented electrical steel sheet may be 90 µm to 150 µm.

[0022] In the present embodiment, in the hot rolling step, the slab may be reheated to 1100°C to 1210°C, and the reheated slab may be hot rolled at a finishing rolling temperature of 800°C to 950°C.

[0023] In this embodiment, the pre-annealing temperature in the pre-annealing step may be 900°C to 1040°C.

[0024] In this embodiment, the cold rolling annealing temperature in the cold rolling annealing step may be 900°C to 990°C.

[0025] In the present embodiment, the slab may further include carbon (C): more than 0 wt% and less than or equal to 0.003 wt%, phosphorus (P): more than 0 wt% and less than or equal to 0.1 wt%, nitrogen (N): more than 0 wt% and less than or equal to 0.003 wt%, and titanium (Ti): more than 0 wt% and less than or equal to 0.003 wt%.

[0026] Another embodiment of the present invention provides a non-oriented electrical steel sheet, which comprises, in wt%, silicon (Si): 1.8 wt% to 2.8 wt%, manganese (Mn): 0.1 wt% to 0.5 wt%, aluminum (Al): 0.1 wt% to 0.7 wt%, sulfur (S): more than 0 wt% and 0.003 wt% or less, a total of at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y): 0.0005 wt% to 0.0034 wt%, the remainder being iron (Fe) and unavoidable impurities.

[0027] In this embodiment, the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among all sulfide inclusions can satisfy the following relationship 3.

[0028] <Relationship 3>

[0029] A / B * 100 ≤ 20%

[0030] In the above relational expression 3, A may be the number of sulfide inclusions having a diameter of 10 nm to 100 nm, and B may be the total number of sulfide inclusions.

[0031] In this embodiment, the aggregate structure of the non-oriented electrical steel sheet {110} <110> The orientation function can be 3 to 5.

[0032] In the present embodiment, the sum of the contents of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y), the ratio of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions, and the aggregate structure {110} of the non-oriented electrical steel sheet <110> The orientation function can satisfy the following relationship 4.

[0033] <Relationship 4>

[0034]

[0035] In the above relational expression 4, L is the sum of the contents of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y), S is the ratio of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions, and T is the {110} texture of the non-oriented electrical steel sheet. <110> may be a defense function.

[0036] In this embodiment, the non-oriented electrical steel sheet has a core loss (W) of less than 3.28 W / kg. 15 / 50 (standard) can be used.

[0037] In this embodiment, the non-oriented electrical steel sheet has a magnetic flux density (B) of 1.69 T or more. 50 (standard) can be used.

[0038] In this embodiment, the average grain size of the non-oriented electrical steel sheet may be 90 µm to 150 µm.

[0039] Other aspects, features and advantages other than those described above will become apparent from the following detailed description, claims and drawings for carrying out the invention.

[0040] According to one embodiment of the present invention, as described above, the magnetic properties of a non-oriented electrical steel sheet can be improved by controlling the alloy composition of the non-oriented electrical steel sheet. Of course, the scope of the present invention is not limited by these effects.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] In the examples below, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Referring to Fig. 1, a method for manufacturing a non-oriented electrical steel sheet may include a hot rolling step (S100), a preliminary annealing step (S200), a cold rolling step (S300), and a cold annealing step (S400).

[0052] 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.

[0053] First, the slab can be manufactured through a continuous casting process. The slab can contain silicon (Si), manganese (Mn), aluminum (Al), sulfur (S), rare earth elements, the remainder iron (Fe), and unavoidable impurities. Here, the rare earth elements can include one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y). In addition, the slab can further contain carbon (C), phosphorus (P), nitrogen (N), and titanium (Ti).

[0054] Specifically, the slab may contain, in wt%, silicon (Si): 1.8 wt% to 2.8 wt%, manganese (Mn): 0.1 wt% to 0.5 wt%, aluminum (Al): 0.1 wt% to 0.7 wt%, sulfur (S): more than 0 wt% and 0.003 wt% or less, rare earth elements: 0.0005 wt% to 0.0034 wt%, the remainder iron (Fe) and unavoidable impurities. Here, the rare earth elements may include at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y). Accordingly, the slab may contain at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y) in a total amount of 0.0005 wt% to 0.0034 wt%. Preferably, the slab may contain at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y) in a total amount of 0.0005 wt% or more and 0.0032 wt% or less.

[0055] Additionally, the slab may further include carbon (C): more than 0 wt% and less than or equal to 0.003 wt%, phosphorus (P): more than 0 wt% and less than or equal to 0.1 wt%, nitrogen (N): more than 0 wt% and less than or equal to 0.003 wt%, and titanium (Ti): more than 0 wt% and less than or equal to 0.003 wt%.

[0056] Silicon (Si) can be a major additive element that increases the resistivity of the manufactured non-oriented electrical steel sheet and lowers the core loss. Silicon (Si) can be included in an amount of 1.8 wt% to 2.8 wt%. If silicon (Si) is included in an amount less than 1.8 wt%, it may be difficult for the manufactured non-oriented electrical steel sheet to achieve the target core loss value. That is, if silicon (Si) is included in an amount less than 1.8 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 2.8 wt%, the magnetic flux density may decrease, the difficulty of the production process may increase, and the manufacturing cost may increase. In addition, the present invention is characterized in that the magnetic characteristics of a non-oriented electrical steel sheet manufactured by adding at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y) to a slab in a total amount of 0.0005 wt% or more and 0.0034 wt% or less (preferably, 0.0005 wt% or more and 0.0032 wt% or less) can be improved. However, when the content of silicon (Si) exceeds 2.8 wt%, the content of silicon (Si) may be too high and the effect of adding rare earth elements may be minimal.

[0057] Manganese (Mn) can be an element that increases the resistivity of non-oriented electrical steel sheets manufactured with silicon, reduces iron loss, and forms sulfur (S) and sulfide inclusions (e.g., MnS). Manganese (Mn) can be included in an amount of 0.1 wt% to 0.5 wt%. If manganese (Mn) is included in an amount of less than 0.1 wt%, the iron loss improvement effect may be insufficient. On the other hand, if manganese (Mn) is included in an amount of more than 0.5 wt%, sulfide inclusions (e.g., MnS) may be finely precipitated, increasing iron loss.

[0058] Aluminum (Al) increases the resistivity of non-oriented electrical steel sheets manufactured with silicon, thereby reducing iron loss, and can form nitride-based inclusions (e.g., AlN) with nitrogen (N). Aluminum (Al) may be included in an amount of 0.1 wt% to 0.7 wt%. When the aluminum (Al) content is less than 0.1 wt%, fine nitride-based inclusions (e.g., AlN) may precipitate, which may have a negative effect on magnetism. On the other hand, when the aluminum (Al) content exceeds 0.7 wt%, problems may occur in the steelmaking / casting process.

[0059] Sulfur (S) may be a component that increases iron loss and inhibits grain growth by forming precipitates such as MnS and TiS. Therefore, it may be desirable to have a low sulfur content in the slab. Sulfur may be included in an amount greater than 0 wt% and less than or equal to 0.003 wt%. When sulfur is included in an amount greater than 0.003 wt%, precipitates such as MnS and TiS may be formed, increasing iron loss and inhibiting grain growth.

[0060] Carbon (C) is a component that increases iron loss by forming carbides such as TiC, so a lower carbon content within the slab may be desirable. Carbon may be included in an amount greater than 0 wt% and less than 0.003 wt%. If carbon 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 is included in an amount less than 0.003 wt%, the self-aging phenomenon may be suppressed.

[0061] Phosphorus (P) may be a grain boundary segregation element that develops the texture. Phosphorus may be included in an amount greater than 0 wt% and less than or equal to 0.1 wt%. If phosphorus is included in an amount greater than 0.1 wt%, grain growth may be suppressed due to the segregation effect, magnetic properties may be deteriorated, and cold rolling properties may be reduced.

[0062] Nitrogen (N) can form precipitates such as AlN and TiN, thereby increasing iron loss and inhibiting grain growth. Therefore, it may be desirable to have a low nitrogen content in the slab. Nitrogen may be included in an amount greater than 0 wt% and less than or equal to 0.003 wt%. If nitrogen is included in an amount greater than 0.003 wt%, precipitates such as AlN and TiN may be formed, thereby increasing iron loss and inhibiting grain growth.

[0063] Titanium (Ti) can inhibit grain growth by forming fine precipitates such as TiC, TiN, and TiS. As more titanium is added, the magnetic properties deteriorate, so it may be desirable to add as little titanium as possible. Titanium can be included in amounts greater than 0 wt% and less than or equal to 0.003 wt%. When titanium is included in amounts greater than 0.003 wt%, it can form fine precipitates such as TiC, TiN, and TiS, inhibiting grain growth and possibly resulting in deteriorated magnetic properties.

[0064] In one embodiment, the slab may comprise at least 0.0005 wt% and at most 0.0034 wt% of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y). Preferably, the slab may comprise at least 0.0005 wt% and at most 0.0032 wt% of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y). When the sum of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) satisfies 0.0005 wt% or more and 0.0034 wt% or less (preferably 0.0005 wt% or more and 0.0032 wt% or less), the amount (or number) of sulfide inclusions having a diameter of 10 nm to 100 nm among the entire sulfide inclusions can be reduced, and {110} <110> The iron loss of the manufactured non-oriented electrical steel sheet can be reduced and the magnetic flux density can be increased because the texture can be increased. For example, when the sum of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) satisfies 0.0005 wt% or more and 0.0034 wt% or less (preferably, 0.0005 wt% or more and 0.0032 wt% or less), the ratio of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions can be 20% or less, and the texture {110} <110> Since the orientation function can satisfy 3 to 5, the iron loss of the non-oriented electrical steel sheet manufactured through this can be reduced and the magnetic flux density can be increased.

[0065] When the sum of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) is less than 0.0005 wt%, the content of rare earth elements may be too small to exhibit the aforementioned effect. On the other hand, when the sum of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) exceeds 0.0034 wt%, the iron loss is reduced, but the magnetic flux density may also be reduced, resulting in poor magnetic properties.

[0066] 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.

[0067] First, the hot rolling step (S100) can reheat the slab. The slab reheating temperature can be 1100°C to 1210°C. If the slab reheating temperature is lower than 1100°C, 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 1210°C, 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.

[0068] The hot rolling step (S100) can roll the slab at a predetermined finishing rolling temperature. At this time, the finishing rolling temperature can be 800°C to 950°C.

[0069] Additionally, the hot rolling step (S100) can cool and coil the hot-rolled steel plate to a predetermined coiling temperature (CT). At this time, the coiling temperature can be 550°C to 650°C.

[0070] The thickness of the hot-rolled sheet manufactured through the hot rolling step (S100) may be 1.6 mm to 2.6 mm. 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 deteriorated texture.

[0071] A pre-annealing step (S200) may be performed after the hot rolling step (S100). In the pre-annealing step (S200), the hot-rolled hot-rolled sheet may be pre-annealed.

[0072] In the preliminary annealing step (S200), the hot-rolled sheet may be heated to a preliminary annealing temperature (e.g., holding temperature) at a heating rate (or heating rate) of 10°C / s or more, then annealed (e.g., held) at the preliminary annealing temperature for 30 s to 100 s, and then cooled at a cooling rate of 10°C / s or more. At this time, the preliminary annealing temperature (e.g., holding temperature) may be 900°C to 1040°C. Preferably, the preliminary annealing temperature (e.g., holding temperature) may be 900°C to 1030°C. When the preliminary annealing temperature is less than 900°C, the grain size may be fine, which may increase the hysteresis loss. On the other hand, when the preliminary annealing temperature exceeds 1040°C (preferably, exceeds 1030°C), fine sulfides may increase, which may increase the iron loss of the manufactured non-oriented electrical steel sheet.

[0073] After the pre-annealing step (S200), a cold rolling step (S300) may be performed. In the cold rolling step (S300), a pre-annealed hot-rolled sheet may be cold rolled to produce a cold-rolled sheet. For example, a steel sheet that has undergone the cold rolling step (S300) may be referred to as a cold-rolled sheet.

[0074] Shot blasting and pickling may be performed prior to the cold rolling stage (S300).

[0075] In the cold rolling step (S300), the pre-annealed plate can be cold rolled to a thickness of 0.55 mm or less. For example, the thickness of the cold-rolled plate manufactured through the cold rolling step (S300) may be 0.35 mm to 0.55 mm. At this time, in order to impart rollability, the plate temperature may be increased to 150°C to 200°C to perform warm rolling. However, the present invention is not limited thereto. Cold rolling may also be performed at room temperature.

[0076] The reduction ratio in the cold rolling stage (S300) can be 65% to 87%.

[0077] A cold rolling annealing step (S400) may be performed after the cold rolling step (S300). At this time, the cold rolling annealing step (S400) may be referred to as the final annealing step. In the cold rolling annealing step (S400), the cold-rolled cold-rolled sheet may be annealed.

[0078] In the cold rolling annealing step (S400), the cold rolled sheet is heated to a cold rolling annealing temperature (e.g., holding temperature) at a heating rate (or heating rate) of 10°C / s to 80°C / s, then annealed (e.g., held) at the cold rolling annealing temperature for 30 s to 90 s, and then cooled at a cooling rate of 30°C / s to 100°C / s. At this time, the cold rolling annealing temperature (e.g., holding temperature) may be 900°C to 990°C. When the cold rolling annealing temperature is less than 900°C, the grain size may be fine, which may increase the hysteresis loss. On the other hand, when the annealing temperature is more than 990°C, {110} <110> The iron loss of non-oriented electrical steel sheets manufactured with a reduced grain structure may increase.

[0079] In one embodiment, the average grain size after annealing may be from 90 μm to 150 μm.

[0080] The cold rolling annealing step (S400) can be performed under a mixed gas atmosphere to prevent surface oxidation and nitriding. For example, a mixed gas atmosphere of nitrogen and hydrogen can be used to further smooth the surface.

[0081] After the cold-rolled annealing step (S400), a coating layer can be formed on the cold-rolled annealed cold-rolled sheet. By forming the coating layer, the punchability can be improved and the insulation can be secured.

[0082] In one embodiment, a non-oriented electrical steel sheet can be manufactured through a hot rolling step (S100) to a cold rolling annealing step (S400).

[0083] A non-oriented electrical steel sheet according to one embodiment of the present invention may include silicon (Si), manganese (Mn), aluminum (Al), sulfur (S), rare earth elements, the remainder iron (Fe), and unavoidable impurities. In this case, the rare earth elements may include one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y).

[0084] Specifically, the non-oriented electrical steel sheet may contain, in wt%, silicon (Si) of 1.8 wt% to 2.8 wt%, manganese (Mn) of 0.1 wt% to 0.5 wt%, aluminum (Al) of 0.1 wt% to 0.7 wt%, sulfur (S) of more than 0 wt% and 0.003 wt% or less, rare earth elements in total: 0.0005 wt% to 0.0034 wt%, the remainder iron (Fe) and unavoidable impurities. At this time, the rare earth elements may include at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y). Therefore, the non-oriented electrical steel sheet may include at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y) in a total amount of 0.0005 wt% to 0.0034 wt%. Preferably, the non-oriented electrical steel sheet may contain at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y) in a total amount of 0.0005 wt% or more and 0.0032 wt% or less.

[0085] In addition, the non-oriented electrical steel sheet may further include carbon (C): more than 0 wt% and less than 0.003 wt%, phosphorus (P): more than 0 wt% and less than 0.1 wt%, nitrogen (N): more than 0 wt% and less than 0.003 wt%, and titanium (Ti): more than 0 wt% and less than 0.003 wt%.

[0086] In one embodiment, the average grain size of the non-oriented electrical steel sheet may be from 90 μm to 150 μm.

[0087] In one embodiment, the core loss of the non-oriented electrical steel sheet (e.g., W 15 / 50The standard) may be less than 3.28 W / kg. Preferably, the core loss of the non-oriented electrical steel sheet (e.g., W 15 / 50 The standard) may be 2.5 W / kg or more and 3.25 W / kg or less. More preferably, the iron loss of the non-oriented electrical steel sheet (e.g., W 15 / 50 The standard) may be 2.5 W / kg or more and 3.23 W / kg or less.

[0088] In one embodiment, the magnetic flux density of the non-oriented electrical steel sheet (e.g., B 50 The standard) can be 1.69 T or more. Specifically, the magnetic flux density of the non-oriented electrical steel sheet (e.g., B 50 The standard) may be 1.69 T or more and 1.76 T or less. Preferably, the magnetic flux density of the non-oriented electrical steel sheet (e.g., B 50 The standard) can be 1.70T or more and 1.76T or less.

[0089] Inclusions formed by impurities can interfere with the magnetization process of non-oriented electrical steel sheets, which can increase iron loss and decrease magnetic flux density. Specifically, the movement of domain walls is essential during the magnetization process, and sulfide inclusions (e.g., MnS, TiS, etc.) formed by sulfur (S) contained in the slab (or non-oriented electrical steel sheet) can interfere with the movement of the domain walls, which can increase iron loss and decrease magnetic flux density. In this case, among the sulfide inclusions, sulfide inclusions having a diameter of 10 nm to 100 nm, which is similar to the thickness of the domain walls, can interfere with the movement of the domain walls the most.

[0090] Therefore, when the amount (or number) of sulfide inclusions having a diameter of 10 nm to 100 nm among sulfide inclusions is reduced, the magnetization inhibition effect can be reduced, so that the iron loss of the manufactured non-oriented electrical steel sheet can be reduced and the magnetic flux density can be increased.

[0091] In addition, the grain structure is an important factor that determines the magnetism of non-oriented electrical steel sheets and is usually <111> → <110> → <100> It is known that the more you have, the more advantageous it is for you. For example, <100> Collective organization and <110> As the aggregate structure increases, the magnetic properties can be improved, <111> When the aggregate structure increases, the magnetic properties may deteriorate. In this case, to improve the magnetic properties, <100> Increasing the collective organization is best, but second best is <110> The magnetic properties can be improved by increasing the aggregate structure. In the present invention, rare earth elements are added to the slab (or, non-oriented electrical steel sheet). <110> By increasing the amount of aggregate tissue, the magnetic properties can be improved.

[0092] In one embodiment, when a rare earth element is added to a slab (or, non-oriented electrical steel sheet), the rare earth element may react with sulfur to form sulfide inclusions, and the sulfide inclusions formed by the reaction of the rare earth element with sulfur may have a diameter larger than 100 nm, so that the amount (or number, ratio) of sulfide inclusions having a diameter of 10 nm to 100 nm among all sulfide inclusions may be reduced. At this time, the rare earth element may include one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y).

[0093] Specifically, when rare earth elements are added to a slab (or non-oriented electrical steel sheet), the rare earth elements and sulfur may react to form sulfide inclusions. At this time, the sulfide inclusions formed by the reaction between the rare earth elements and sulfur may have a diameter larger than 100 nm. In addition, the sulfide inclusions formed by the reaction between the rare earth elements and sulfur have a diameter larger than 100 nm, so that the amount (or number, ratio) of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions is reduced, thereby improving the magnetic properties of the manufactured non-oriented electrical steel sheet.

[0094] In addition, when rare earth elements are added to slabs (or non-oriented electrical steel sheets), the rare earth elements and sulfur react to form sulfide inclusions, forming {110} <110> The aggregate structure can be increased, which can improve the magnetic properties of the manufactured non-oriented electrical steel sheet.

[0095] In a non-oriented electrical steel sheet and a manufacturing method thereof according to one embodiment of the present invention, a rare earth element is added to a slab (or non-oriented electrical steel sheet) to reduce the amount (or number) of sulfide inclusions having a diameter of 10 nm to 100 nm among sulfide inclusions, thereby improving the magnetic properties of the manufactured non-oriented electrical steel sheet.

[0096] In addition, in the non-oriented electrical steel sheet and the manufacturing method thereof according to one embodiment of the present invention, rare earth elements are added to the slab (or non-oriented electrical steel sheet) to form {110} <110> The magnetic properties of non-oriented electrical steel sheets manufactured by increasing the aggregate structure can be improved.

[0097] Specifically, by adding one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) to a slab (or non-oriented electrical steel sheet) in a total amount of 0.0005 wt% or more and 0.0034 wt% or less (preferably 0.0005 wt% or more and 0.0032 wt% or less) to cause neodymium (Nd) and / or yttrium (Y) and sulfur (S) to react to form sulfide inclusions, the iron loss of the manufactured non-oriented electrical steel sheet can be reduced and the magnetic flux density can be increased by reducing the amount (or number, ratio) of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions. In addition, by adding one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) to a slab (or, non-oriented electrical steel sheet) in a total amount of 0.0005 wt% or more and 0.0034 wt% or less (preferably, 0.0005 wt% or more and 0.0032 wt% or less), and causing neodymium (Nd) and / or yttrium (Y) and sulfur (S) to react to form sulfide inclusions, {110} <110> The iron loss of non-oriented electrical steel sheets manufactured by increasing the aggregate structure can be reduced and the magnetic flux density can be increased.

[0098] As described above, the slab (or non-oriented electrical steel sheet) may contain at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y) in a total amount of 0.0005 wt% or more and 0.0034 wt% or less (preferably, 0.0005 wt% or more and 0.0032 wt% or less). When the total amount of at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y) satisfies 0.0005 wt% or more and 0.0034 wt% or less (preferably, 0.0005 wt% or more and 0.0032 wt% or less), the amount (or number, ratio) of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions may be reduced, and {110} <110> The iron loss of the manufactured non-oriented electrical steel sheet can be reduced and the magnetic flux density can be increased because the aggregate structure can be increased.

[0099] In one embodiment, the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions may be 20% or less. For example, when the number of the total sulfide inclusions is B and the number of sulfide inclusions having a diameter of 10 nm to 100 nm is A, the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions may satisfy the following relationship 1.

[0100] <Relationship 1>

[0101] A / B * 100 ≤ 20%

[0102] At this time, if the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions exceeds 20%, the amount (or number) of sulfide inclusions having a diameter of 10 nm to 100 nm that impede the movement of the domain wall may be too large, which may impede the movement of the domain wall, thereby increasing iron loss and decreasing magnetic flux density. For example, if the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions exceeds 20%, the non-oriented electrical steel sheet may have high iron loss and low magnetic flux density.

[0103] In one embodiment, the sum of the contents of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) is L, the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions is S, and the texture {110} <110> When the orientation function is T, the sum (L) of the contents of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y), the proportion (S) of sulfide inclusions having a diameter of 10 nm to 100 nm among all sulfide inclusions, and the aggregate texture {110} <110> The orientation function (T) can satisfy the following relationship 2.

[0104] <Relationship 2>

[0105]

[0106] By adding rare earth elements to the slab, the amount (or number) of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions can be reduced, and {110} <110> The aggregate structure can be increased. Specifically, when the sum of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) satisfies 0.0005 wt% or more and 0.0034 wt% or less (preferably 0.0005 wt% or more and 0.0032 wt% or less), the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions can be 20% or less, and the aggregate structure {110} <110> The orientation function can satisfy 3 to 5.

[0107] When the total of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) is added in a slab in an amount of less than 0.0005 wt%, the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions may exceed 20%, and the texture {110} <110> The magnetic flux density may be less than 3. On the other hand, if the total amount of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) is added to the slab in an amount exceeding 0.0034 wt%, the magnetic flux density may be reduced.

[0108] When the total of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) is added in a slab in an amount of less than 0.0005 wt%, the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions may exceed 20%, and the texture {110} <110> The azimuth function may be less than 3, so the value of relation 2 may be less than 20, and when the value of relation 2 is less than 20, the iron loss (W) is greater than 3.28 W / kg. 15 / 50 (standard) can be used.

[0109] Even when the sum of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) in the slab is satisfied, if the pre-annealing temperature (e.g., the holding temperature) of the pre-annealing step (S200) exceeds 1040°C, the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among the entire sulfide inclusions may exceed 20%, so that the value of relational expression 2 may be less than 20, and if the value of relational expression 2 is less than 20, the iron loss (W) of 3.28 W / kg or more may be 15 / 50 (standard) can be used.

[0110] In addition, even when the sum of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) is satisfied within the slab, when the cold rolling annealing temperature (e.g., holding temperature) of the cold rolling annealing step (S400) exceeds 990°C, the texture {110} <110> The azimuth function may be less than 3, so the value of relation 2 may be less than 20, and when the value of relation 2 is less than 20, the iron loss (W) is greater than 3.28 W / kg. 15 / 50 (standard) can be used.

[0111] When the value of relational expression 2 exceeds 45, the magnetic flux density may decrease. For example, when the value of relational expression 2 exceeds 45, the magnetic flux density may be less than 1.69 T. Specifically, when the sum of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y) in the slab exceeds 0.0034 wt%, the value of relational expression 2 may exceed 45, and when the value of relational expression 2 exceeds 45, the magnetic flux density may be less than 1.69 T.

[0112] Therefore, the sum (L) of the contents of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y), the proportion (S) of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions, and the texture {110} <110> If the orientation function (T) satisfies Equation 2, the non-oriented electrical steel sheet can have excellent magnetic properties.

[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] Distinctive component (wt%) SiMnAl Rare earth element NdY Total [L] Example 12.010.300.520.00010.00300.0031 Example 22.000.300.530.00300.00010.0031 Example 31.980.290.510.00140.00160.0030 Example 41.990.300.500.00010.00200.0021 Example 51.990.310.500.00190.00010.0020 Example 62.000.320.490.00110.00110.0022 Example 71.820.280.490.00020.00250.0027Example 82.250.270.490.00260.00010.0027Example 92.590.290.510.00280.00020.0030Example 102.780.300.510.00020.00270.0029

[0116] Classification Component (wt%) CSPNTi Example 10.00210.00200.00610.00250.0019 Example 20.00240.00220.00530.00170.0017 Example 30.00220.00210.00960.00230.0023 Example 40.00240.00220.00840.00230.0020 Example 50.00210.00190.00630.002 50.0021Embodiment 60.00180.00180.00780.00200.0021Embodiment 70.00220.00170.00730.00210.0018Embodiment 80.00240.00180.00800.00180.0024Embodiment 90.00240.00180.00510.00200.0022Embodiment 100.00180.00190.00590.00240.0017

[0117] Classification Component (wt%) SiMnAl Rare Earth Element NdY Total [L] Comparative Example 12.010.310.510.00020.00020.0004 Comparative Example 22.000.310.520.00020.00010.0003 Comparative Example 32.030.280.470.00010.00280.0029 Comparative Example 42.050.290.520.00280.00010.0029 Comparative Example 52.060.310.480.00010.00260.0027 Comparative Example 62.000.270.490.00270.00010.0028 Comparative Example 72.010.320.530.00020.00290.0031Comparative example 81.970.330.510.00280.00010.0029Comparative example 91.950.290.520.00150.00130.0028Comparative example 101.990.300.520.00350.00010.0036Comparative example 111.980.320.500.00020.00370.0039Comparative example 121.970.320.470.00500.00010.0051Comparative example 131.980.300.480.00020.00500.0052Comparative example 142.000.290.490.00300.00320.0062Comparative example 151.780.300.490.00100.00120.0022Comparative example 162.820.310.500.00120.00100.0022

[0118] Distinctive component (wt%) CSPNTi Comparative example 10.00160.00190.00920.00180.0017Comparative example 20.00160.00200.00810.00160.0018Comparative example 30.00170.00190.00700.00150.0017Comparative example 40.00160.00180.00840.00250.0019Comparative example 50.00240.00180.00530.00230.0025Comparative example 60.00240.00180.00870.00200.0024Comparative example 70.00240.0020.00930.00230.0019Comparative example 80.00240.00220.00880.00170.0025Comparative example 90.00220.00220.00750.00230.0020Comparative example 100.00190.00210.00840.00220.0018Comparative example 110.00220.00220.00590.00180.0020Comparative example 120.00210.00210.00850.00240.0020Comparative example 130.00190.00210.00820.00160.0016Comparative example 140.00220.00190.00680.00170.0019Comparative example 150.00170.00200.00590.00240.0016Comparative example 160.00190.00210.00610.00170.0022

[0119] Hot rolling stage Slab reheating temperature (℃) 1160 Finish rolling temperature (℃) 850 Coiling temperature (℃) 580 Hot rolling thickness (mm) 2.3 Preliminary annealing stage Heating rate (℃ / s) 10 Holding time (s) 100 Cooling rate (℃ / s) 10 Whether shot blasting and pickling are performed O Cold rolling stage Reduction ratio (%) 78.2 Cold rolling thickness (mm) 0.5 Cold rolling annealing stage Heating rate (℃ / s) 40 Holding time (s) 45 Cooling rate (℃ / s) 40

[0120] Classification Preliminary annealing temperature (℃) Cold rolling annealing temperature (℃) Example 1 1000947 Example 2 999951 Example 3 1005953 Example 4 1003952 Example 5 1003951 Example 6 1001950 Example 7 997950 Example 8 9999951 Example 9 9999952 Example 10 1001952

[0121] Classification Preliminary annealing temperature (℃) Cold rolling annealing temperature (℃) Comparative example 11001949 Comparative example 21000948 Comparative example 31049949 Comparative example 41055952 Comparative example 59991001 Comparative example 61001999 Comparative example 710491003 Comparative example 810551002 Comparative example 910521001 Comparative example 10999948 Comparative example 111000952 Comparative example 121001953 Comparative example 13998950 Comparative example 141003951 Comparative example 15999950 Comparative example 16999948

[0122] The proportion of sulfide inclusions of a specific diameter among all sulfide inclusions, the value of the equation for the aggregate structure, and the magnetic properties of the equation 2 are 10~100 nm (%) [S]{110} <110> [T]Iron Loss(W 15 / 50 ,W / kg) magnetic flux density (B 50 , T) Example 1 10.5 3.7 4 0.4 1 8 3.1 5 1.7 1 Example 2 10.9 3.8 4 1.0 6 8 3.1 4 1.7 2 Example 3 10.7 3.9 4 2.6 4 5 3.1 7 1.7 1 Example 4 11.13.5 2 3.1 7 6 3.2 2 1.7 2 Example 5 11.33.6 2 2.9 3 8 3.2 3 1.7 1 Example 6 113.4 2 3.1 2 0 3.2 3 1.7 1 Example 7 11.13.5 2 9.7 9 7 3.2 0 1.7 2 Example 8 10.9 3.4 2 8.6 3 5 3.0 9 1.7 2 Example 9 10.83.4 3 2.1 1 1 3.0 1 1.7 1 Example 10113.328.7102.971.70

[0123] The proportion of sulfide inclusions of a specific diameter among all sulfide inclusions, the value of the equation for the aggregate structure, and the magnetic properties of the equation 2 are 10~100 nm (%) [S]{110} <110> [T]Iron Loss(W 15 / 50 ,W / kg) magnetic flux density (B 50, T) Comparative Example 121.12.00.7583.301.70 Comparative Example 220.62.30.7703.331.71 Comparative Example 329.13.411.5203.291.70 Comparative Example 4283.311.2793.311.71 Comparative Example 511.12.717.7323.281.71 Comparative Example 611.32.819.4273.321.70 Comparative Example 721.32.710.6103.411.71 Comparative Example 821.62.69.0763.441.69 Comparative Example 9222.68.6043.291.70 Comparative Example 1010.33.747.8493.131.67Comparative example 1110.13.855.7583.111.67Comparative example 129.93.978.3553.111.68Comparative example 139.83.980.7063.101.67Comparative example 149.24.0107.8263.101.68Comparative example 1513.62.913.6043.331.73Comparative example 1614.73.013.4693.021.68

[0124] Examples 1 to 10 and Comparative Examples 1 to 16 are samples manufactured using slabs composed of the components shown in Tables 1, 2, 3 and 4, the remainder iron (Fe), and unavoidable impurities, under the process conditions shown in Tables 5, 6 and 7, respectively.

[0125] Examples 1 to 10 and Comparative Examples 1 to 16 were manufactured under the same conditions except for the component content, pre-annealing temperature, and cold rolling annealing temperature. At this time, all samples were manufactured to the same size of 80 mm in width and 150 mm in length.

[0126] The number of sulfide inclusions was measured through SEM-EDS analysis. Specifically, observation specimens (15x15mm in size) were collected from the manufactured samples, and mirror-polished to less than 1㎛ were performed on the surface (ND plane) and the center of the specimen (center of thickness). The analysis area was 160 mm at the center of the thickness direction of the specimen. 2Above, analysis was performed under the conditions of magnification: x100, dwell time: 0.1 second. In addition, after measuring more than 2000 fields based on a spherical diameter of 0.4㎛ per detecting pixel unit, 100 mm 2 The average number of inclusions per area was calculated.

[0127] The texture was measured using EBSD. At this time, the texture {110} <110> When the amount of disordered assembly organization is considered as 1, it corresponds to the amount of assembly organization in that direction.

[0128] The value of relational expression 2 is the sum of the contents of rare earth elements (L), the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among all sulfide inclusions (S), and the texture {110}. <110> It corresponds to the value of relation 2 related to the orientation function (T).

[0129] The magnetic properties were measured twice in the rolling direction and the direction perpendicular to the rolling direction using a Single Sheet Tester (SST) and the average value was obtained. At this time, W 15 / 50 refers to the iron loss when a magnetic flux density of 1.5 Tesla is induced at a frequency of 50 Hz, and B 50 It refers to the magnetic flux density induced when a magnetic field of 5000 A / m is applied.

[0130] Referring to Table 8, in the case of Examples 1 to 10, the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among all sulfide inclusions is 20% or less, and the aggregate texture {110} <110> It can be confirmed that the orientation function satisfies 3 to 5, and the value of relational expression 2 satisfies 20 to 45. Therefore, it can be confirmed that Examples 1 to 10 have excellent magnetic properties by having relatively low iron loss and high magnetic flux density.

[0131] On the other hand, Comparative Examples 1 and 2 are cases where rare earth elements are added to slabs (or non-oriented electrical steel sheets) in an amount of less than 0.0005 wt%, and Comparative Examples 1 and 2 have a ratio of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions exceeding 20%, and a texture {110}. <110> It can be confirmed that the azimuth function is less than 3 and the value of relational expression 2 is less than 20. Therefore, it can be confirmed that when the rare earth element content is less than the required content, a relatively high iron loss is obtained.

[0132] Comparative Examples 3 and 4 are cases where the pre-annealing temperature exceeds 1040°C, and it can be confirmed that when the pre-annealing temperature exceeds 1040°C, the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among all sulfide inclusions exceeds 20%. That is, even when the required content of rare earth elements is satisfied, it can be confirmed that when the pre-annealing temperature is high, sulfide inclusions having a diameter of 10 nm to 100 nm are not reduced, resulting in a relatively high iron loss.

[0133] Comparative Examples 5 and 6 are cases where the cold rolling annealing temperature exceeds 990°C, and when the cold rolling annealing temperature exceeds 990°C, the texture {110} <110> It can be confirmed that the azimuth function is less than 3. That is, even if the rare earth element satisfies the required content, if the cold rolling annealing temperature is high, {110} <110> It can be confirmed that the iron loss is relatively high because the fraction of the aggregate organization does not increase.

[0134] Comparative Examples 7, 8 and 9 are cases where the pre-annealing temperature is more than 1040°C and the cold rolling annealing temperature is more than 990°C. In cases where the pre-annealing temperature is more than 1040°C and the cold rolling annealing temperature is more than 990°C, the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among all sulfide inclusions is more than 20%, and the texture {110} <110> It can be confirmed that the azimuth function is less than 3. That is, even if the rare earth element satisfies the required content, if the pre-annealing temperature and cold rolling annealing temperature do not satisfy the required conditions, it can be confirmed that it has a relatively high iron loss and low magnetic flux density (in the case of Comparative Example 8).

[0135] Comparisons 10 to 14 are cases where rare earth elements are added in excess of 0.0034 wt% to the slab (or non-oriented electrical steel sheet). It can be confirmed that when rare earth elements are added in excess of 0.0034 wt% to the slab (or non-oriented electrical steel sheet), the magnetic flux density decreases without any further iron loss reduction effect.

[0136] Comparative Example 15 is a case where less than 1.8 wt% of silicon (Si) is added to a slab (or non-oriented electrical steel sheet). It can be confirmed that when less than 1.8 wt% of silicon (Si) is included in a slab (or non-oriented electrical steel sheet), a relatively high iron loss is obtained.

[0137] Comparative Example 16 is a case where silicon (Si) is added in excess of 2.8 wt% to a slab (or non-oriented electrical steel sheet). It can be confirmed that when silicon (Si) is included in excess of 2.8 wt% in a slab (or non-oriented electrical steel sheet), it has a relatively low magnetic flux density.

[0138] 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 non-oriented electrical steel sheet, A hot rolling step of manufacturing a hot-rolled sheet by hot-rolling a slab including, in wt%, silicon (Si): 1.8 wt% to 2.8 wt%, manganese (Mn): 0.1 wt% to 0.5 wt%, aluminum (Al): 0.1 wt% to 0.7 wt%, sulfur (S): more than 0 wt% and 0.003 wt% or less, a total of at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y): 0.0005 wt% to 0.0034 wt%, the remainder iron (Fe) and unavoidable impurities; A preliminary annealing step for preliminary annealing the above hot-rolled plate; A cold rolling step for manufacturing a cold rolled sheet by cold rolling the above pre-annealed hot rolled sheet; and A cold rolling annealing step of cold rolling the above cold rolled cold rolled sheet; A method for manufacturing a non-oriented electrical steel sheet, comprising:

2. In paragraph 1, A method for manufacturing a non-oriented electrical steel sheet, wherein the ratio of sulfide inclusions having a diameter of 10 nm to 100 nm among all sulfide inclusions satisfies the following relationship 1. <Relationship 1> A / B * 100 ≤ 20% In the above relational expression 1, A is the number of sulfide inclusions having a diameter of 10 nm to 100 nm, and B is the total number of sulfide inclusions.

3. In paragraph 2, The aggregate structure of the above non-oriented electrical steel sheet {110} <110> A method for manufacturing a non-oriented electrical steel sheet having a direction function of 3 to 5.

4. In paragraph 3, The sum of the contents of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y), the ratio of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions, and the aggregate structure {110} of the non-oriented electrical steel sheet <110> A method for manufacturing a non-oriented electrical steel sheet, wherein the orientation function satisfies the following relational expression 2. <Relationship 2> In the above relational expression 2, L is the sum of the contents of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y), S is the ratio of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions, and T is the {110} texture of the non-oriented electrical steel sheet. <110> is the orientation function.

5. In paragraph 1, The above non-oriented electrical steel sheet has a core loss (W) of less than 3.28 W / kg. 15 / 50 A method for manufacturing a non-oriented electrical steel sheet having a standard.

6. In paragraph 1, The above non-oriented electrical steel sheet has a magnetic flux density (B) of 1.69 T or more. 50 A method for manufacturing a non-oriented electrical steel sheet having a standard.

7. In paragraph 1, A method for manufacturing a non-oriented electrical steel sheet, wherein the pre-annealing temperature in the above pre-annealing step is 900°C to 1040°C.

8. In paragraph 1, A method for manufacturing a non-oriented electrical steel sheet, wherein the cold rolling annealing temperature in the above cold rolling annealing step is 900°C to 990°C.

9. In paragraph 1, A method for manufacturing a non-oriented electrical steel sheet, wherein the above slab further contains carbon (C) in wt% greater than 0 wt% and 0.003 wt% or less, phosphorus (P) in wt% greater than 0 wt% and 0.1 wt% or less, nitrogen (N) in wt% greater than 0 wt% and 0.003 wt% or less, and titanium (Ti) in wt% greater than 0 wt% and 0.003 wt% or less.

10. As a non-oriented electrical steel sheet, A non-oriented electrical steel sheet comprising, in wt%, silicon (Si): 1.8 wt% to 2.8 wt%, manganese (Mn): 0.1 wt% to 0.5 wt%, aluminum (Al): 0.1 wt% to 0.7 wt%, sulfur (S): more than 0 wt% and 0.003 wt% or less, a total of at least one element selected from the group consisting of neodymium (Nd) and yttrium (Y): 0.0005 wt% to 0.0034 wt%, the remainder iron (Fe) and unavoidable impurities.

11. In paragraph 10, A non-oriented electrical steel sheet, wherein the proportion of sulfide inclusions having a diameter of 10 nm to 100 nm among all sulfide inclusions satisfies the following relationship 3. <Relationship 3> A / B * 100 ≤ 20% In the above relational expression 3, A is the number of sulfide inclusions having a diameter of 10 nm to 100 nm, and B is the total number of sulfide inclusions.

12. In paragraph 11, The aggregate structure of the above non-oriented electrical steel sheet {110} <110> A method for manufacturing a non-oriented electrical steel sheet having a direction function of 3 to 5.

13. In paragraph 12, The sum of the contents of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y), the ratio of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions, and the aggregate structure {110} of the non-oriented electrical steel sheet <110> A non-oriented electrical steel sheet whose orientation function satisfies the following relational expression 4. <Relationship 4> In the above relational expression 4, L is the sum of the contents of one or more elements selected from the group consisting of neodymium (Nd) and yttrium (Y), S is the ratio of sulfide inclusions having a diameter of 10 nm to 100 nm among the total sulfide inclusions, and T is the {110} texture of the non-oriented electrical steel sheet. <110> is the orientation function.

14. In paragraph 10, The above non-oriented electrical steel sheet has a core loss (W) of less than 3.28 W / kg. 15 / 50 Non-oriented electrical steel sheet having a standard.

15. In paragraph 10, The above non-oriented electrical steel sheet has a magnetic flux density (B) of 1.69 T or more. 50 Non-oriented electrical steel sheet having a standard.

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