Non-oriented electrical steel sheet and method for manufacturing the same

Abstract

The present invention provides a non-oriented electrical steel sheet and a method for producing the same, in which Si, Al, Mn, Cu, and Cr components for increasing resistivity and In, Sn, Sb, P, and Mg components for improving texture are added to the steel sheet, and the process conditions are also controlled to improve both strength and core loss of the steel sheet. [Solution] A method for producing a non-oriented electrical steel sheet of the present invention includes a step of producing a slab in a steelmaking process by adding, by weight, 2.8-3.8% Si, 0.5-1.5% Al, 0.3-2.0% Mn, 0.01-0.2% Cu, and 0.01-0.5% Cr, and adding 0.0005-0.015% In, 0.0050-0.08% Sn, 0.0050-0.05% Sb, and 0.0050-0.06% P to the basic components, and controlling Mg to a range of 0.002-0.05%, a slab heating step of heating the slab, a hot rolling step of final finish rolling the slab, a hot rolled sheet annealing step of annealing the hot rolled sheet, a cold rolling step of rolling the hot rolled sheet, and a final annealing step of annealing the cold rolled sheet.

Description

Technical Field

[0001] The present invention relates to a non-oriented electromagnetic steel sheet and a method for manufacturing the same. More specifically, the present invention adds components that increase the specific resistance and components that improve the grain structure to the steel sheet, and further controls the process conditions together to obtain a non-oriented electromagnetic steel sheet in which the strength and iron loss of the steel sheet are excellent at the same time, and a method for manufacturing the same.

Background Art

[0002] Recently, due to climate change, global attention and efforts for carbon neutrality have been increasing for environmental conservation of the earth. In relation to carbon neutrality, efficient use of electric energy has become a major issue for improving the global environment, such as energy conservation, reduction of fine particulate matter generation, and reduction of greenhouse gas emissions. Since more than 50% of the total electric energy currently generated is consumed by electric motors, in fact, high efficiency of electric motors is essential for efficient use of electricity. Recently, as the field of environmentally friendly vehicles (hybrid, plug-in hybrid, electric vehicle, fuel cell vehicle) has been rapidly developing, the interest in high-efficiency drive motors has been increasing rapidly. The electrification of vehicles, which is rapidly progressing mainly in electric vehicles, has attracted attention in the direction of enhancing the characteristics of drive motors.

[0003] The characteristics required for drive motors for electric vehicles are to further increase the driving range and simultaneously increase the maximum speed. Such goals are directly related to the low iron loss and high strength characteristics of the electromagnetic steel sheet used in drive motors. If the yield strength of the electromagnetic steel sheet is high, the rotational speed of the drive motor can be increased, and the iron loss is low, so that the efficiency can be further improved and the driving range can be further increased. Therefore, high strength and high-frequency low iron loss characteristics of electromagnetic steel sheets are essential. For this purpose, efforts are being made in the direction of ensuring high-frequency low iron loss and high strength by containing Si even higher than the normal content of Si in electromagnetic steel sheets and adding large amounts of Al, Mn, and Cr. However, simply adding large amounts of resistivity elements such as Si, Al, Mn, and Cr to electrical steel sheets to reduce grain size and increase strength has limitations in satisfying the ever-increasing limits on maximum speed and long-distance driving characteristics of drive motors, and therefore also limits the improvement of the physical properties of electrical steel sheets. Consequently, there is an increasing need to improve the properties of the material itself by changing the internal structure of non-oriented electrical steel sheets used in electric vehicle drive motors. [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present invention provides non-oriented electrical steel sheets and methods for manufacturing the same. Specifically, it provides non-oriented electrical steel sheets and methods for manufacturing the same, in which Si, Al, Mn, Cu, and Cr components that increase resistivity and In, Sn, Sb, P, and Mg components that improve texture are added to the steel sheet, and process conditions are also controlled to simultaneously improve the strength and iron loss of the steel sheet. [Means for solving the problem]

[0005] The non-oriented electrical steel sheet of the present invention has the following composition by weight %, Si: 2.8~3.8%, Al: 0.5~1.5%, Mn: 0.3~2.0%, Cu : 0.01-0.2%, Cr : The 0.01-0.5% component consists of In: 0.0005-0.015%, Sn: 0.0050-0.08%, Sb: 0.0050-0.05%, P: 0.0050-0.06%, and Mg: 0.002-0.05%, with the remainder being Fe and other unavoidable impurities. The non-oriented electrical steel sheet of the present invention satisfies the relationship between the content of In, Sn, Sb, P, and Mg and the size of the crystal grains shown in the following formula [Equation 1]. [Formula 1] [Mg]≦([In]*[Sn]) / ([Sb]*[P])≦Crystal grain size (mm)*20

[0006] The non-oriented electrical steel sheet of the present invention further comprises one or more of the following: C: 0.0040 or less (0% excluded), S: 0.0040 or less (0% excluded), N: 0.0040 or less (0% excluded), and Ti: 0.0040 or less (0% excluded). The resistivity is 50 μΩ·cm or more. Also, ND / / <114> The proportion of collective organizations is 5% or more. The following equation [Equation 2] relating yield strength by crystal orientation is satisfied. [Formula 2] Ys(RD*10.3)≦Ys(45゜)≦Ys(TD)

[0007] The present invention relates to a method for manufacturing non-oriented electrical steel sheets, in which, in the steelmaking process, Si: 2.8~3.8%, Al: 0.5~1.5%, Mn: 0.3~2.0%, Cu : 0.01-0.2%, Cr : The process includes the steps of: manufacturing a slab by adding 0.01-0.5% of the basic components, along with In: 0.0005-0.015%, Sn: 0.0050-0.08%, Sb: 0.0050-0.05%, and P: 0.0050-0.06%, and controlling Mg: to a range of 0.002-0.05%; a slab heating step of heating the slab; a hot rolling step of final finishing rolling of the slab at 800°C or higher; a hot rolled sheet annealing step of annealing the hot rolled sheet; a cold rolling step of rolling the hot rolled sheet with a reduction ratio of 70-95%; and a final annealing step of annealing the cold rolled sheet at 800-1,000°C. The following [Equation 1] is satisfied. [Formula 1] [Mg]≦([In]*[Sn]) / ([Sb]*[P])≦Crystal grain size (mm)*20

[0008] The method for manufacturing non-oriented electrical steel sheets of the present invention further comprises one or more of the following: C: 0.0040 or less (0% excluded), S: 0.0040 or less (0% excluded), N: 0.0040 or less (0% excluded), and Ti: 0.0040 or less (0% excluded). The resistivity of electrical steel sheets is 50 μΩ·cm or higher or ND / / <114> The fraction of aggregate tissue is 5% or more, or one or more of the following yield strength-related conditions [Equation 2] are satisfied. [Equation 2] Ys(RD*1.03)≦Ys(45゜)≦Ys(TD) The slab is heated to 1,100-1,250°C. The hot-rolled sheet is annealed at 850-1,150°C. [Effects of the Invention]

[0009] According to the non-oriented electrical steel sheet of the present invention, a superior non-oriented electrical steel sheet for electric vehicle drive motors is provided, which has Si, Al, Mn, Cu, and Cr as basic components to increase resistivity, and in, Sn, Sb, and P to promote segregation, while simultaneously adding Mg to inhibit segregation, and by controlling the manufacturing process conditions while doing so, the optimal component ratio according to the grain size is derived, thereby increasing both yield strength and iron loss simultaneously. Furthermore, the yield strength increases as it moves from the rolling direction to the direction perpendicular to the rolling direction, improving its suitability for high-speed rotation, while simultaneously achieving a technical effect that provides excellent iron loss characteristics. Furthermore, when manufactured as a drive motor, it can drive the motor with a small current even at high rotational speeds, and it also boasts excellent motor efficiency. Ultimately, this contributes to the manufacture of environmentally friendly automotive motors, high-efficiency home appliance motors, and super-premium electric motors. [Modes for carrying out the invention]

[0010] The terms first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited to these. These terms are used solely to distinguish one part, component, region, layer, or section from other parts, components, regions, layers, or sections. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the invention. The technical terms used herein are for the sole purpose of referring to specific embodiments and are not intended to limit the invention. The singular form used herein also includes plural forms unless the phrase explicitly indicates otherwise. The meaning of “includes” as used in this specification is to embody specific characteristics, regions, integers, stages, operations, elements, and / or components, and does not exclude the presence or addition of other characteristics, regions, integers, stages, operations, elements, and / or components. When one part is described as being "on top of" or "above" another part, it means that it is directly on top of or above the other part, or that the other part is present between them. In contrast, when one part is described as being "directly on top of" another part, there is no other part in between them.

[0011] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as those generally understood by a person of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have the meaning corresponding to the relevant technical literature and the content now disclosed, and are not interpreted in their ideal or highly formal sense unless otherwise defined. Also, unless otherwise specified, % means weight percent, and 1 ppm is 0.0001 weight percent. In this invention, the inclusion of additional elements means that the additional amount of the additional elements replaces the remaining iron (Fe). The embodiments of the present invention will be described below in detail so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. However, the present invention can be realized in a variety of different forms and is not limited to the embodiments described herein. In this invention, yield strength and iron loss are simultaneously improved by efficiently controlling the Si, Al, Mn, Cu, and Cr components that increase resistivity in non-oriented steel sheets, while also controlling the In, Sn, Sb, and P components that promote segregation and the Mg component that inhibits segregation, thereby altering the texture.

[0012] The non-oriented electrical steel sheet of the present invention contains, by weight%, Si: 2.8 to 3.8%, Al: 0.5 to 1.5%, Mn: 0.3 to 2.0%, Cu : 0.01 to 0.2%, Cr : It contains In: 0.0005 to 0.015%, Sn: 0.0050 to 0.08%, Sb: 0.0050 to 0.05%, P: 0.0050 to 0.06%, and Mg: 0.002 to 0.05% in the components of 0.01 to 0.5%, and the balance consists of Fe and unavoidable impurities. First, an explanation will be given from the reasons for limiting the components of the non-oriented electrical steel sheet.

[0013] [Si: 2.8 to 3.8 wt%] Silicon (Si) plays a role in increasing the specific resistance of the material to reduce iron loss while ensuring high strength, so a large amount must be added. When Si is added too little, the effect of improving high-frequency iron loss cannot be expected and the strength is not sufficient. When added too much, the hardness of the material increases and the productivity and punching property become inferior, which is not preferable. Therefore, Si can be contained in an amount of 2.8 to 3.8 wt%.

[0014] [Al: 0.5 to 1.5 wt%] Aluminum (Al) plays a role in increasing the specific resistance of the material to reduce iron loss while ensuring high strength at the same time. If Al is added too little, it has no effect on reducing high-frequency iron loss and ensuring high strength, and nitrides may be finely formed to reduce magnetism. On the contrary, if added too much, it may cause problems of changing the physical properties of the mold flux in processes such as steelmaking and continuous casting, and greatly reduce productivity. Therefore, Al can be added within the above range. More specifically, Al can be contained in an amount of 0.3 to 2.0 wt%.

[0015] [Mn: 0.3 to 2.0 wt%] Manganese (Mn) plays a role in increasing the resistivity of the material, improving iron loss, and promoting sulfide formation. If too little Mn is added, fine MnS deposits may form, reducing magnetism. Conversely, if too much is added, it may promote the formation of a {111} texture unfavorable to magnetism, leading to a decrease in magnetic flux density. Therefore, it is preferable to include 0.3 to 2.0% by weight of Mn.

[0016] [Cu:0.01~0.2wt%] Copper (Cu), along with manganese (Mn), plays a role in forming sulfides. If too little Cu is added, fine CuMnS deposits may form, degrading the magnetism. Conversely, if too much Cu is added, high-temperature embrittlement may occur, leading to crack formation in the steel sheet during continuous casting or hot rolling processes. Therefore, it is preferable to include 0.01 to 0.2% by weight of Cu.

[0017] [Cr:0.01~0.50wt%] Chromium (Cr) plays a role in increasing the resistivity of the material and reducing iron loss. If the amount of Cr is too low, there is no resistivity improvement effect, and if the amount of Cr is too high, the magnetic flux density decreases and the magnetic properties deteriorate. Therefore, it is preferable to include 0.01 to 0.50% by weight of Cr.

[0018] [Amounts of In, Sn, Sb, and P added] Indium (In), tin (Sn), antimony (Sb), and phosphorus (P) can be segregated at grain boundaries by appropriately controlling the annealing conditions. To obtain the grain boundary segregation effect from the addition of In, Sn, Sb, and P, the concentrations of these components are preferably In: 0.0005~0.015%, Sn: 0.0050~0.08%, Sb: 0.0050~0.05%, and P: 0.0050~0.06%. Below the respective addition ranges of In, Sn, Sb, and P, there is no grain boundary segregation effect, and above these ranges, the brittleness of the material increases. Therefore, it is preferable to limit the amounts within the proposed ranges.

[0019] [Mg:0.002~0.1wt%] Magnesium (Mg) plays a role in improving iron loss by forming coarser sulfides. If too little Mg is added, it cannot adequately perform this role and forms fine sulfides, degrading the magnetism. Conversely, if too much Mg is added, sulfides cannot be formed, and residual Mg remains, degrading the iron loss. Furthermore, even if the amount of Mg is within the allowed range, it can sometimes form compounds with segregating elements, degrading magnetism. Therefore, even if the amount of Mg added is within the allowed range, it is preferable to control the amount added so that it is less than the ([In]*[Sn]) / ([Sb]*[P]) value, as shown in [Equation 1] below. [Formula 1] [Mg]≦([In]*[Sn]) / ([Sb]*[P])≦Crystal grain size (mm)*20 The meaning of equation 1 is that, in order to maximize the segregation effect by controlling the amount of segregating elements added, the elements that promote segregation and the elements that inhibit segregation should be appropriately adjusted. Therefore, in the case of Mg, since it has the ability to combine with segregating elements to form intermetallic compounds, it is preferable to limit it to the range [Mg] ≤ ([In] * [Sn]) / ([Sb] * [P]).

[0020] If the amount of Mg added exceeds the range shown in [Equation 1], it is not easy to achieve only the desired magnetic and strength improvement effects without segregation effects. Furthermore, when grain boundary segregation is formed by the addition of segregating elements, it is affected by the size of the crystal grains of the steel sheet, i.e., the grain size. That is, if the grain size of the steel sheet becomes coarser, the amount of segregation decreases and there is no segregation effect, so it is preferable to control the content of the segregating elements within the range related to the grain size [Equation 1]. Thus, if the grain size grows larger than the relationship between the amount of segregating element addition according to [Equation 1], it is not easy to expect a segregation effect.

[0021] The non-oriented electrical steel sheet of the present invention may further contain one or more of the following: C: 0.0040 or less (0% excluded), S: 0.0040 or less (0% excluded), N: 0.0040 or less (0% excluded), and Ti: 0.0040 or less (0% excluded). If additional elements are included, they may be included in place of the remainder Fe. Here, C, N, and Ti form carbonitrides and play a role in hindering magnetic domain movement, so it is preferable to limit them within the aforementioned range. Similarly, S forms sulfides and impairs grain growth, so for this reason, it is also preferable to limit it within the aforementioned range.

[0022] The non-oriented electrical steel sheet of the present invention may further contain other elements that are inevitably present in addition to the above-mentioned components. Unavoidable impurities refer to impurities that are intentionally added or inevitably mixed in during the steelmaking and non-oriented electrical steel sheet manufacturing processes. Since unavoidable impurities are widely known, a detailed explanation will be omitted. Furthermore, this invention does not exclude the addition of elements other than the alloy components mentioned above, but rather allows for a variety of elements to be included as long as it does not impair the technical concept of this invention. If additional elements are included, they shall be included in place of the remaining Fe.

[0023] [Specific resistance: 50 μΩ cm or more] The resistivity of steel plates is calculated from 13.25 + 11.3 × ([Si] + [Al] + [Mn] / 2 + [Cu] / 2 + [Cr] / 2). In this formula, [Si], [Al], [Mn], [Cu], and [Cr] represent the content (weight %) of Si, Al, Mn, Cu, and Cr, respectively. A higher resistivity helps to reduce iron loss. If the resistivity is too low, iron loss will be poor, making it difficult to use as a high-efficiency motor, and if it is too high, the magnetic flux density may be poor. For use in high-speed rotating motors, the resistivity needs to be controlled to 50 μΩ·cm or higher.

[0024] [ND / / <114> [Percentage: 5% or more] The steel sheet of the present invention developed in the thickness direction (ND) perpendicular to the rolling direction. <114> Fraction of collective organization relative to direction (ND / / <114> The fraction may be 5% or more. The ND / / <114> fraction of the steel sheet is investigated using SEM-EBSD within an allowable error angle of 5°. Since the Young's modulus in this orientation is large in the rolling direction (RD) and the direction perpendicular to the rolling plane (TD), as the proportion of this orientation increases, the yield strength value of Ys(TD±α) becomes larger compared to the yield strength Ys(RD) in the rolling direction. If segregation occurs frequently, the ND / / <114> fraction becomes 5% or more, ensuring the Ys(RD)<Ys(TD±α) characteristic. At this time, the α value ranges from 5 to 90°. [Yield strength: Ys] In the present invention, the yield strength according to each crystal direction of the steel sheet satisfies the following [Equation 2]. [Equation 2] Ys(RD*1.03)≦Ys(45°)≦Ys(TD) The yield strength of the steel sheet was measured by a tensile test, and the 2% off-set strength was used to eliminate the influence of the deformation rate. In [Equation 2], Ys(RD) is the yield strength in the rolling direction, and the value multiplied by the exponent 1.03 is used as the comparison target. Ys(TD) is the yield strength in the direction perpendicular to the rolling plane direction. Also, the yield strength inclined 45 degrees from the rolling direction is expressed as Ys(45°). In one embodiment of the present invention, when the yield strength of the steel sheet satisfies the conditions of [Equation 2], the iron loss is also improved.

[0025] Hereinafter, the manufacturing method of the non-oriented electrical steel sheet of the present invention will be described. The manufacturing method of the non-oriented electrical steel sheet of the present invention includes, in the steelmaking process, Si: 2.8 to 3.8% by weight, Al: 0.5 to 1.5% by weight, Mn: 0.3 to 2.0% by weight, Cu : 0.01 to 0.2% by weight, Cr : 0.01 to 0.5% by weight, and to the basic components, In: 0.0005 to 0.015% by weight, Sn: 0.0050 to 0.08% by weight, Sb: 0.0050 to 0.05% by weight, P: 0.0050 to 0.06% by weight are added, and Mg is controlled within the range of 0.002 to 0.05% by weight to produce a slab, heating the slab, hot rolling the slab to produce a hot-rolled sheet, cold rolling the hot-rolled sheet to produce a cold-rolled sheet, and finally annealing the cold-rolled sheet. Non-oriented electrical steel sheets manufactured by this method satisfy the following [Equation 1]. [Formula 1] [Mg]≦([In]*[Sn]) / ([Sb]*[P])≦Crystal grain size (mm)*20

[0026] The following sections will provide a detailed explanation of each stage. First, let's explain the process of manufacturing the slab. The reasons for limiting the constituent elements within the slab are the same as those for limiting the composition of the non-oriented electrical steel sheet mentioned above, so we will omit the repeated explanation. Since the composition of the slab does not change substantially during the manufacturing processes described later, such as hot rolling, hot-rolled sheet annealing, cold rolling, and final annealing, the composition of the slab and the composition of the non-oriented electrical steel sheet are substantially the same. The slab can be heated before the stage of manufacturing the hot-rolled sheet. Specifically, the slab is placed in a heating furnace and heated to 1,100-1,250°C. When heated at temperatures exceeding 1,250°C, precipitates may be redissolved and finely precipitated after hot rolling.

[0027] The heated slab is hot-rolled to a thickness of 2-2.3 mm to produce a hot-rolled sheet. The final finishing rolling temperature may be 800°C or higher during the production of the hot-rolled sheet. The process may further include a stage of annealing the hot-rolled sheet after the stage of manufacturing the hot-rolled sheet. In this case, the annealing temperature of the hot-rolled sheet may be 850 to 1,150°C. If the annealing temperature is below 850°C, the microstructure will not grow or will grow only slightly, resulting in little increase in magnetic flux density. If the annealing temperature exceeds 1,150°C, the magnetic properties may actually decrease, and the deformation of the sheet shape may worsen the rolling workability. More specifically, the temperature range may be 950 to 1,125°C. Annealing of the hot-rolled sheet is performed as needed to increase the orientations favorable to magnetism, and it can be omitted.

[0028] Next, the hot-rolled sheet is pickled and cold-rolled to the desired thickness. Depending on the thickness of the hot-rolled sheet, a reduction ratio of 70-95% can be applied to cold-roll the sheet to achieve a final thickness of 0.2-0.65 mm. To achieve the correct reduction ratio, one cold-rolling pass or two or more cold-rolling passes with intermediate annealing in between can be performed. During the manufacturing process of the cold-rolled sheet, the maximum rolling speed may be 10 m / s or more. The cold-rolled sheet undergoes final annealing. During the final annealing stage, the sheet can be uniformly heated to 800-1,000°C. To optimize grain boundary segregation, a lower annealing temperature is preferable, but the annealing temperature must increase as the sheet thickness decreases. If the uniform heating temperature is below 800°C, sufficient recrystallization will not occur, and if the final annealing temperature exceeds 1,000°C, the segregation effect will disappear. During cooling after soaking, the material can be cooled at a rate of 10-40°C / s from the soaking temperature down to 700°C. The cooling rate is adjusted within a range that does not cause excessive grain growth and negatively impact high-frequency iron loss. More specifically, it can be cooled at a rate of 15-35°C / s. The process may further include a step of forming an insulating layer. Since methods for forming insulating layers are widely known in the field of non-oriented electrical steel sheet technology, a detailed explanation will be omitted.

[0029] The following describes preferred embodiments and comparative examples of the present invention. However, the following embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to these embodiments. [Examples]

[0030] Example 1 Slabs were manufactured with the composition shown in Table 1 below. The components were controlled to match those listed in Table 1, with the remainder being Fe. The slabs were heated to 1,150°C and hot-finished-rolled at 850°C to produce hot-rolled sheets with a thickness of 2.0 mm. The hot-rolled sheets were annealed at 1,100°C for 4 minutes and then pickled. Next, the sheet was cold-rolled to a reduction ratio of 87.5% to a thickness of 0.25 mm, followed by final annealing. The final annealing was performed at 950°C for 3 minutes. For the non-oriented electrical steel sheets manufactured in this manner, the composition of the steel sheets is as follows: white The resistivity calculated from, and the size of the crystal grains measured by the area method, ND / / <114> The fractional yield strengths and yield strengths in each direction of the texture were measured and are shown in Table 2 below. Texture was measured using SEM-EBSD, and the texture was within the tolerance range. horn The degree of offset was kept within 5 degrees, and the yield strength was calculated from the 2% offset strength.

[0031] [Table 1]

[0032] [Table 2]

[0033] As shown in Tables 1 and 2, the examples that satisfy the alloy composition and manufacturing process conditions are ND / / <114> When the fraction exceeds 5%, the rate of increase in yield strength increases by more than 3% as the deviation from the rolling direction increases, and it can be confirmed that the iron loss is also excellent. On the other hand, steel grades 4, 10, and 13, which contain even more Mg than the calculated value of ([In]*[Sn]) / ([Sb]*[P]), are ND / / <114> The fraction of this component is less than 4%, indicating that the segregation effect is minimal, and thus confirming that the strength improvement effect in each direction is also minimal.

[0034] Furthermore, steel grades 1, 3, 5, and 7 satisfy the conditions of [Equation 1] specified in the embodiments of the present invention, satisfy all the conditions of [Equation 2] related to the yield strength in each direction, and ensure sufficient iron loss. In addition, steel grades 1, 3, 5, and 7 all have resistivity of 50 μΩ·cm or more, and ND / / <114> It was also found that the fraction was 5% or more. However, steel grades 2, 4, 6, 8-13 that deviate from the composition range of the present invention, or that, even if within the composition range, do not satisfy the conditions of [Formula 1], are ND / / <114> It can be confirmed that the fraction is 5% or less, or that the yield strength values ​​for each direction of the aggregate tissue do not satisfy [Equation 2]. The present invention is not limited to the embodiments described above, and can be manufactured in a variety of different forms. Those with ordinary skill in the art to which the present invention belongs should understand that it can be implemented in other specific forms without altering the technical idea or essential features of the present invention. Therefore, the embodiments described above should be understood to be illustrative and not limiting in all respects.

Claims

1. The composition, by weight percent, is Si: 2.8–3.8%, Al: 0.5–1.5%, Mn: 0.3–2.0%, Cu: 0.01–0.2%, Cr: 0.01–0.50%, with In: 0.0005–0.015%, Sn: 0.0050–0.08%, Sb: 0.0050–0.05%, P: 0.0050–0.06%, and Mg: 0.002–0.05%, with the remainder being Fe and other unavoidable impurities. A non-oriented electrical steel sheet characterized in that the fraction of the ND / / <114> texture is 5% or more.

2. The non-oriented electrical steel sheet according to claim 1, characterized in that the content of In, Sn, Sb, P, and Mg and the size of the crystal grains satisfy the relationship shown in [Equation 1] below. [Formula 1] [Mg]≦([In]*[Sn]) / ([Sb]*[P])≦crystal grain size (mm)*20

3. C: 0.0040% or less (0% excluded), S: 0.0040% or less (0% excluded), N: 0.0040% or less (excluding 0%), and The non-oriented electrical steel sheet according to claim 1, further comprising one or more types of Ti: 0.0040% or less (excluding 0%).

4. The non-oriented electrical steel sheet according to claim 1, characterized in that the resistivity of the non-oriented electrical steel sheet is 50 μΩ·cm or more.

5. The non-oriented electrical steel sheet according to claim 1 is characterized in that it satisfies the following relationship between yield strength by crystal direction [Equation 2]. [Formula 2] Ys(RD)*1.03≦Ys(45°)≦Ys(TD) In Equation 2, Ys(RD) is the yield strength in the rolling direction, and Ys(TD) is in the rolling plane direction. This is the yield strength in the vertical direction, and Ys(45°) is the yield strength at a 45-degree angle from the rolling direction.

6. In the steelmaking process, the basic components are: Si: 2.8-3.8% by weight, Al: 0.5-1.5%, Mn: 0.3-2.0%, Cu: 0.01-0.2%, Cr: 0.01-0.50%, with In: 0.0005-0.015%, Sn: 0.0050-0.08%, Sb: 0.0050-0.05%, and P: 0.0050-0.06% added, and the Mg content is controlled to be within the range of 0.002-0.05% to produce the slab. Slab heating step in which the slab is heated, The slab is subjected to a hot rolling stage in which it is subjected to final finish rolling at 800°C or higher. The hot-rolled sheet annealing stage, in which the hot-rolled sheet is annealed. A cold rolling step in which the hot-rolled sheet is rolled with a reduction ratio of 70 to 95%, and This includes a final annealing step in which the cold-rolled sheet is annealed at 800 to 1,000°C. A method for manufacturing non-oriented electrical steel sheets, characterized in that the fraction of ND / / <114> texture in the manufactured non-oriented electrical steel sheet is 5% or more.

7. The method for manufacturing a non-oriented electrical steel sheet according to claim 6, characterized in that the non-oriented electrical steel sheet satisfies the relationship between the content of In, Sn, Sb, P, and Mg and the size of the crystal grains shown in the following formula [Equation 1]. [Formula 1] [Mg]≦([In]*[Sn]) / ([Sb]*[P])≦crystal grain size (mm)*20

8. C: 0.0040% or less (0% excluded), S: 0.0040% or less (0% excluded), N: 0.0040% or less (excluding 0%), and A method for manufacturing a non-oriented electrical steel sheet according to claim 6, further comprising one or more of the following: Ti: 0.0040% or less (excluding 0%).

9. The method for manufacturing a non-oriented electrical steel sheet according to claim 6, characterized in that the resistivity of the non-oriented electrical steel sheet is 50 μΩ·cm or more, or satisfies one or more of the conditions related to yield strength shown below [Equation 2]. [Formula 2] Ys(RD)*1.03≦Ys(45°)≦Ys(TD)

10. The method for manufacturing a non-oriented electrical steel sheet according to claim 6, characterized in that the slab heating step is performed at 1,100 to 1,250°C.

11. The method for manufacturing a non-oriented electrical steel sheet according to claim 6, characterized in that the hot-rolled sheet annealing step is performed at 850 to 1,150°C.

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