Non-oriented electrical steel sheet and method for producing same

Abstract

The present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same, and more particularly, to a non-oriented electrical steel sheet which can be preferably used as an iron core or the like of a motor, and a method for manufacturing the same. One aspect of the invention aims to provide a non-oriented electrical steel plate with low high-frequency iron loss and a manufacturing method of the non-oriented electrical steel plate.

Description

Technical Field

[0001] The present invention relates to a non-oriented electrical steel sheet and a manufacturing method thereof, and more particularly, to a non-oriented electrical steel sheet that can be preferably used for cores of electric motors and the like, and a manufacturing method thereof. Background Art

[0002] In recent years, as the disasters caused by climate change have increased, countries around the world are releasing carbon neutral roadmaps for 2050. The total carbon emissions reached 3.9 billion tons in 2020, of which the emissions from internal combustion engines accounted for 24%, reaching 940 million tons. Therefore, the demand for carbon neutrality in this field by electrifying internal combustion engines is very high. For this reason, in the field of transportation, electrification led by electric vehicles is rapidly progressing. In new transportation means, the required characteristics of drive motors are to increase the driving range and the maximum speed. This is directly related to the low iron loss characteristics of electrical steel sheets.

[0003] Generally, in order to improve the recrystallization texture, a method of suppressing the formation of orientations with poor magnetism by grain boundary segregation elements is used. However, if a large amount of segregation elements are used, the brittleness of the steel will increase, resulting in the disadvantage of poor rolling productivity. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] One aspect of the present invention aims to provide a non-oriented electrical steel sheet with low high-frequency iron loss and a manufacturing method thereof.

[0006] (II) Technical Solutions

[0007] One embodiment of the present invention provides a non-oriented electrical steel sheet, which, by weight%, contains: Si: 3.3 - 4.3%, Al: 0.8 - 1.7%, Mn: 0.3 - 2.0%, Cu: 0.03 - 0.5%, Sn: 0.01 - 0.1%, S: 0.002 - 0.01%, the balance being Fe and other inevitable impurities. The non-oriented electrical steel sheet satisfies the following relational expression 1, and the texture (112)[1 - 31] / texture (112)[1 - 10] strength ratio is 2.0 or more.

[0008] [Relational Expression 1] 0.02 ≤ Sn × S × 100 / Cu ≤ 0.75

[0009] The non-oriented electrical steel sheet may further contain one or more of C: 0.005% or less, N: 0.005% or less, Ti: 0.005% or less, Nb: 0.005% or less, and V: 0.005% or less.

[0010] The non-oriented electrical steel sheet may further contain one or more of P: 0.1% or less, Cr: 0.01 - 0.5%, Sb: 0.1% or less, Ni: 0.05% or less, and Zn: 0.01% or less.

[0011] The non-oriented electrical steel sheet may further contain one or more of Mo: 0.03% or less, B: 0.0050% or less, Ca: 0.005% or less, and Mg: 0.005% or less.

[0012] The non-oriented electrical steel sheet may further contain one or more of Bi, Pb, Ge, and As, and the contents of Bi, Pb, Ge, and As are each 0.20% or less (excluding 0%) or the total amount is 0.20% or less (excluding 0%).

[0013] The strength of the texture (112)[1 - 31] of the non-oriented electrical steel sheet may be 2.5 or more, and the strength of the texture (112)[1 - 10] may be 0.9 or less.

[0014] The resistivity of the non-oriented electrical steel sheet may be 55 μΩcm or more.

[0015] The iron loss (W10 / 400) of the non-oriented electrical steel sheet may be 12.2 W / Kg or less.

[0016] The magnetic flux density (B50) of the non-oriented electrical steel sheet may be 1.66 Tesla or more.

[0017] Another embodiment of the present invention provides a method for manufacturing a non-oriented electrical steel sheet, which includes the following steps: heating a slab at 1100 - 1250 °C, and by weight, the slab contains: Si: 3.3 - 4.3%, Al: 0.8 - 1.7%, Mn: 0.3 - 2.0%, Cu: 0.03 - 0.5%, Sn: 0.01 - 0.1%, S: 0.002 - 0.01%, the balance being Fe and other inevitable impurities, and satisfying the following relational expression 1; hot finish rolling the heated slab at 800 - 1000 °C to obtain a hot rolled sheet; cold rolling the hot rolled sheet with a reduction ratio of 70 - 95% to obtain a cold rolled sheet; and a final annealing step of soaking the cold rolled sheet at 950 - 1020 °C for 30 - 60 seconds, wherein, during the final annealing, the tension on the inlet side of the annealing furnace is 0.5 - 1.0 kgf / mm 2 and controlling the holding time in the range of 600 - 750 °C to be 24 seconds or less during heating to the soaking temperature.

[0018] [Relational expression 1] 0.02 ≤ Sn × S × 100 / Cu ≤ 0.75

[0019] The slab may further contain one or more of C: 0.005% or less, N: 0.005% or less, Ti: 0.005% or less, Nb: 0.005% or less, and V: 0.005% or less.

[0020] The slab may further contain one or more of P: 0.1% or less, Cr: 0.01 - 0.5%, Sb: 0.1% or less, Ni: 0.05% or less, and Zn: 0.01% or less.

[0021] The slab may further contain one or more of Mo: 0.03% or less, B: 0.0050% or less, Ca: 0.005% or less, and Mg: 0.005% or less.

[0022] The slab may further contain one or more of Bi, Pb, Ge, and As, and the contents of Bi, Pb, Ge, and As are each 0.20% or less (except 0%) or the total amount is 0.20% or less (except 0%).

[0023] It may further include the following step: after the step of obtaining the hot-rolled sheet, annealing the hot-rolled sheet at 850 - 1150 °C.

[0024] The cold rolling may be performed one or two times.

[0025] (III) Advantageous Effects

[0026] According to one aspect of the present invention, a non-oriented electrical steel sheet with low high-frequency iron loss and a manufacturing method thereof can be provided. Best Embodiment

[0027] In order to improve the iron loss of the non-oriented electrical steel sheet, elements Si, Al, and Mn that increase the resistivity are used to increase the resistivity. While using Sn, S, and Cu as elements for controlling segregation, by appropriately controlling the conditions during final annealing, a region with improved texture is obtained, thereby realizing that a non-oriented electrical steel sheet with excellent magnetic properties can be manufactured, and the present invention is completed.

[0028] Hereinafter, a non-oriented electrical steel sheet according to an embodiment of the present invention will be described. First, the alloy composition will be described. Unless otherwise specifically stated, the contents of the alloy compositions described below represent weight %.

[0029] Si: 3.3 - 4.3%

[0030] Si is an element that plays a role in increasing the resistivity of the material to reduce iron loss. When the content of Si is less than 3.3%, the improvement effect of high-frequency iron loss is very small. When the content of Si exceeds 4.3%, due to the increase in hardness, productivity and stamping performance may deteriorate. Therefore, the content of Si is preferably in the range of 3.3 - 4.3%. The lower limit of the Si content is more preferably 3.35%, and even more preferably 3.40%. The upper limit of the Si content is more preferably 4.25%, and even more preferably 4.20%.

[0031] Al: 0.8 - 1.7%

[0032] Al is an element that plays a role in increasing the resistivity of the material to reduce iron loss. When the content of Al is less than 0.8%, there is no high-frequency iron loss reduction effect, and fine nitrides will be formed, resulting in poor magnetic properties. When the content of Al exceeds 1.7%, it will cause problems in changing the physical properties of the mold powder during the continuous casting process, resulting in a significant reduction in productivity. Therefore, the content of Al is preferably in the range of 0.8 - 1.7%. The lower limit of the Al content is more preferably 0.85%, and further preferably 0.90%. The upper limit of the Al content is more preferably 1.65%, and further preferably 1.60%.

[0033] Mn: 0.3 - 2.0%

[0034] Mn is an element that plays a role in increasing the resistivity of the material to improve iron loss and form sulfides. When the content of Mn is less than 0.3%, fine MnS will precipitate, resulting in poor magnetic properties. When the content of Mn exceeds 2.0%, it will promote the formation of the

[111] texture that is not conducive to magnetism, resulting in a rapid decrease in magnetic flux density. Therefore, the content of Mn is preferably in the range of 0.3 - 2.0%. The lower limit of the Mn content is more preferably 0.35%, and further preferably 0.40%. The upper limit of the Mn content is more preferably 1.95%, and even more preferably 1.90%.

[0035] Cu: 0.03 - 0.5%

[0036] Cu plays a role in forming sulfides together with Mn, and precipitates together with S and Sn as segregation elements, thereby hindering segregation. When the content of Cu is less than 0.03%, fine CuMnS will precipitate, resulting in poor magnetism, and will also form fine precipitates with S and Sn, thereby hindering segregation. When the content of Cu exceeds 0.5%, high-temperature brittleness will occur, resulting in cracks during continuous casting or hot rolling. Therefore, the content of Cu is preferably in the range of 0.03 - 0.5%. The lower limit of the Cu content is more preferably 0.04%, and further preferably 0.05%. The upper limit of the Cu content is more preferably 0.45%, and further more preferably 0.40%.

[0037] Sn: 0.01 - 0.1%

[0038] Sn is an element that segregates or precipitates at grain boundaries when annealing conditions are appropriately controlled. In addition, the Sn can also precipitate in combination with Cu to form intermetallic compounds, and can also precipitate as sulfides. When the content of Sn is less than 0.01%, it is difficult to fully obtain the grain boundary segregation or precipitation effect. When the content of Sn exceeds 0.1%, it will precipitate as intermetallic compounds or sulfides, resulting in poor magnetism. Therefore, the content of Sn is preferably in the range of 0.01 - 0.1%. The lower limit of the Sn content is more preferably 0.02%, and further preferably 0.03%. The upper limit of the Sn content is more preferably 0.09%, and further more preferably 0.08%.

[0039] S: 0.002 - 0.01%

[0040] S is an element that segregates or precipitates at grain boundaries when annealing conditions are appropriately controlled. In addition, the S can also precipitate in combination with Cu to form intermetallic compounds, and can also precipitate as sulfides. When the content of S is less than 0.002%, it is difficult to fully obtain the grain boundary segregation or precipitation effect. When the content of S exceeds 0.01%, it will precipitate as intermetallic compounds or sulfides, resulting in poor magnetism. Therefore, the content of S is preferably in the range of 0.002 - 0.01%. The lower limit of the S content is more preferably 0.0025%, further preferably 0.0030%, and most preferably 0.0035%. The upper limit of the S content is more preferably 0.009%, further preferably 0.008%.

[0041] The remaining component is Fe. However, in the general manufacturing process, it is inevitable to mix in unwanted impurities from raw materials or the surrounding environment, so these impurities cannot be excluded. Since these impurities are well known to those of ordinary skill in the general manufacturing process, all of their details will not be specifically described in this specification.

[0042] The non-oriented cold-rolled steel sheet of the present invention may further contain one or more of C: 0.005% or less, N: 0.005% or less, Ti: 0.005% or less, Nb: 0.005% or less, and V: 0.005% or less.

[0043] C: 0.005% or less

[0044] C reacts with N, Ti, Nb, V, etc. to form fine carbides, which play a role in hindering grain growth and magnetic domain movement, and its upper limit is limited to 0.005%. More specifically, the content of C may be 0.0001 - 0.005%. More specifically, the content of C may be 0.0005 - 0.003%.

[0045] N: 0.005% or less

[0046] N combines with Ti, Nb, V, etc. to form nitrides, which play a role in reducing grain growth, so its upper limit is limited to 0.005%. More specifically, the content of N may be 0.0001 - 0.005%. More specifically, the content of N may be 0.0005 - 0.003%.

[0047] Ti: 0.005% or less

[0048] Ti combines with C, N, O, etc. to form fine nitrides or oxides, which play a role in hindering magnetic domain movement, so its upper limit is limited to 0.005%. More specifically, the content of Ti may be 0.0001 - 0.005%. More specifically, the content of Ti may be 0.0005 - 0.003%.

[0049] Nb: 0.005% or less

[0050] Nb combines with C, N, etc. to form fine nitrides, which play a role in hindering magnetic domain movement, so its upper limit is limited to 0.005%. More specifically, the content of Nb may be 0.0001 - 0.005%. More specifically, the content of Nb may be 0.0005 - 0.003%.

[0051] V: 0.005% or less

[0052] V combines with C, N, etc. to form fine nitrides, which play a role in hindering magnetic domain movement, so its upper limit is limited to 0.005%. More specifically, the content of V may be 0.0001 - 0.005%. More specifically, the content of V may be 0.0005 - 0.003%.

[0053] The non-oriented cold-rolled steel sheet of the present invention may further contain one or more of P: 0.1% or less, Cr: 0.01 - 0.5%, Sb: 0.1% or less, Ni: 0.05% or less, and Zn: 0.01% or less.

[0054] P: 0.1% or less

[0055] As a grain boundary segregation element, P deteriorates the strength uniformity in the rolling direction and the direction perpendicular to rolling due to delayed recrystallization, and thus its upper limit is restricted to 0.1%. More specifically, the content of P may be 0.0001 - 0.1%. More specifically, the content of P may be 0.001 - 0.05%.

[0056] Cr: 0.01 - 0.5%

[0057] Cr plays a role in improving iron loss by increasing the resistivity. When the content of Cr is less than 0.01%, the effect of increasing the resistivity may be insufficient. When the content of Cr exceeds 0.5%, the magnetic flux density may be reduced. More specifically, the content of Cr may be 0.02 - 0.3%.

[0058] Sb: 0.1% or less

[0059] As an element segregating at the grain boundary, Sb is added to inhibit the diffusion of nitrogen through the grain boundary, inhibit the {111} texture (which is unfavorable to magnetism), and increase the favorable {100} texture, thereby improving the magnetic properties. When the content of Sb exceeds 0.1%, it hinders grain growth, thereby reducing magnetism and deteriorating the rolling properties. More specifically, the content of Sb may be 0.001 - 0.1%. More specifically, the content of Sb may be 0.005 - 0.08%.

[0060] Ni: 0.05% or less

[0061] Ni reacts with impurity elements to form fine sulfides, carbides, and nitrides, which have an adverse effect on magnetism, and thus its upper limit is restricted to 0.05%. More specifically, the content of Ni may be 0.0001 - 0.050%. More specifically, the content of Ni may be 0.001 - 0.030%.

[0062] Zn: 0.01% or less

[0063] Since Zn as an impurity may deteriorate the magnetism, its upper limit is restricted to 0.01%. More specifically, the content of Zn may be 0.0001 - 0.01%. More specifically, the content of Zn may be 0.001 - 0.008%.

[0064] The non-oriented cold-rolled steel sheet of the present invention may further contain one or more of Mo: 0.03% or less, B: 0.0050% or less, Ca: 0.005% or less, and Mg: 0.005% or less.

[0065] They react with inevitably contained C, S, N, etc. to form fine carbides, nitrides or sulfides, which have an adverse effect on magnetism. Therefore, the upper limit can be restricted as described above.

[0066] The non-oriented cold-rolled steel sheet of the present invention may further contain one or more of Bi, Pb, Ge, and As, and the contents of Bi, Pb, Ge, and As are each 0.20% or less (except 0%) or the total amount is 0.20% or less (except 0%).

[0067] When the above elements are further added, they segregate at the grain boundaries to relieve the stress concentration at the grain boundaries during cold rolling and suppress the recrystallization of <111> / ND-oriented grains during recrystallization annealing as a post-treatment, thereby increasing the magnetic flux density. When they are appropriately added, the above effects can be further obtained. However, if they are contained in excessive amounts, a large amount of segregation will occur, suppressing grain growth, resulting in a deterioration of the magnetic flux density and iron loss instead. More specifically, one or more of Bi, Pb, Ge, and As can be contained at 0.0001 - 0.20% respectively or in total. More specifically, one or more of Bi, Pb, Ge, and As can be contained, and the contents of Bi, Pb, Ge, and As are each 0.001 - 0.10% or the total amount is 0.001 - 0.10%.

[0068] The non-oriented cold-rolled steel sheet of the present invention is preferably such that while satisfying the above alloy composition, it satisfies the following relational expression 1.

[0069] [Relational expression 1] 0.02 ≤ Sn × S × 100 / Cu ≤ 0.75

[0070] Sn, S, and Cu are elements for controlling segregation. If the final annealing conditions are appropriately controlled, the texture (112)[1 - 31] / texture (112)[1 - 10] strength ratio of the texture can be controlled. When the value of Sn × S × 100 / Cu is less than 0.02, the Cu content is relatively large compared to Sn and S, so segregation is difficult. When the value of Sn × S × 100 / Cu exceeds 0.75, segregation is overly developed, deteriorating the magnetism. The lower limit of the Sn × S × 100 / Cu value is more preferably 0.025, and even more preferably 0.03. The upper limit of the Sn × S × 100 / Cu value is more preferably 0.70, and most preferably 0.65.

[0071] The texture (112)[1-31] / texture (112)[1-10] strength ratio of the non-oriented electrical steel sheet of the present invention is preferably 2.0 or more. Even on the same (112) plane, if the strength of the texture corresponding to the [1-31] direction is higher than that corresponding to the [1-10] direction, the magnetic properties will be improved. When the texture (112)[1-31] / texture (112)[1-10] strength ratio is less than 2.0, the magnetic improvement effect cannot be fully obtained. The texture (112)[1-31] / texture (112)[1-10] strength ratio is more preferably 2.2 or more, further preferably 2.4 or more, and most preferably 2.6 or more. On the other hand, in the present invention, the higher the texture (112)[1-31] / texture (112)[1-10] strength ratio, the more advantageous, so no particular limitation is imposed on its upper limit. However, the upper limit of the texture (112)[1-31] / texture (112)[1-10] strength ratio can be, for example, 6.0.

[0072] The strength of the texture (112)[1-31] of the non-oriented electrical steel sheet can be 2.5 or more, and the strength of the texture (112)[1-10] can be 0.9 or less. By satisfying such conditions, the magnetic properties can be improved. The strength of the texture (112)[1-31] is more preferably 2.7 or more, further preferably 2.9 or more, and most preferably 3.1 or more. The strength of the texture (112)[1-10] is more preferably 0.7 or less, and further more preferably 0.5 or less. In the present invention, the higher the strength of the texture (112)[1-31], the more advantageous, so no particular limitation is imposed on its upper limit. However, the upper limit of the strength of the texture (112)[1-31] can be, for example, 6.0. In addition, the lower the strength of the texture (112)[1-10], the more advantageous, so no particular limitation is imposed on its lower limit. However, the lower limit of the strength of the texture (112)[1-10] can be, for example, 0.2.

[0073] The resistivity of the non-oriented electrical steel sheet of the present invention provided as described above can be 55 μΩcm or more, the iron loss (W10 / 400) can be 12.2 W / Kg or less, and the magnetic flux density (B50) can be 1.66 tesla or more. In the present invention, the lower the resistivity and the iron loss (W10 / 400), the more advantageous, so no particular limitation is imposed on their lower limits. On the other hand, the iron loss (W10 / 400) and the magnetic flux density (B50) are based on a steel sheet thickness of 0.25 mm.

[0074] Hereinafter, a method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention will be described.

[0075] First, the slab that satisfies the above alloy composition and relational expression 1 is heated at 1100 - 1250 °C. When the heating temperature of the slab is lower than 1100 °C, in order to make the whole slab reach the same temperature, the holding time becomes too long, resulting in the disadvantage of reduced productivity. When the heating temperature of the slab exceeds 1250 °C, the inclusions generated during continuous casting will be redissolved and finely precipitated during the hot rolling process, resulting in the disadvantage of deteriorated magnetic properties. Therefore, the heating temperature of the slab preferably has a range of 1100 - 1250 °C. The lower limit of the heating temperature of the slab is more preferably 1110 °C, further preferably 1120 °C, and most preferably 1130 °C. The upper limit of the heating temperature of the slab is more preferably 1240 °C, further preferably 1230 °C, and most preferably 1220 °C.

[0076] Then, the heated slab is hot finish rolled at 800 - 1000 °C to obtain a hot rolled sheet. When the hot finish rolling temperature is lower than 800 °C, the temperature during hot rolling is too low, resulting in the disadvantage that it cannot be rolled to the desired thickness. When the hot finish rolling temperature exceeds 1000 °C, there are disadvantages in controlling surface oxidation and shape control. The lower limit of the hot finish rolling temperature is more preferably 810 °C, further preferably 820 °C, and most preferably 830 °C. The upper limit of the hot finish rolling temperature is more preferably 990 °C, further preferably 980 °C, and most preferably 970 °C.

[0077] After the step of obtaining the hot rolled sheet, the hot rolled sheet can also be annealed at 850 - 1150 °C. Through the hot rolled sheet annealing process, the crystal orientation beneficial to magnetism can be increased. When the hot rolled sheet annealing temperature is lower than 850 °C, the grains do not grow or grow finely, which may result in a small increase effect on the magnetic flux density. When the hot rolled sheet annealing temperature exceeds 1150 °C, the magnetic properties may instead deteriorate, and due to the deformation of the sheet shape, the rolling workability may deteriorate. Therefore, the hot rolled sheet annealing temperature can have a range of 850 - 1150 °C. The lower limit of the hot rolled sheet annealing temperature is more preferably 870 °C, further preferably 890 °C, and most preferably 910 °C. The upper limit of the hot rolled sheet annealing temperature is more preferably 1140 °C, further preferably 1130 °C. On the other hand, the hot rolled sheet annealing can be omitted.

[0078] Then, the hot-rolled sheet is cold-rolled at a reduction ratio of 70 - 95% to obtain a cold-rolled sheet. When the cold reduction ratio is less than 70%, the deformed structure is uneven, thus having the drawback that the magnetic deviation of the final product may become larger. When the cold reduction ratio exceeds 95%, it is not conducive to the development of the texture for magnetism, thus having the drawback that the magnetism of the final product may deteriorate. Therefore, the cold reduction ratio is preferably in the range of 70 - 95%. The lower limit of the cold reduction ratio is more preferably 72%, further preferably 74%, and most preferably 76%. The upper limit of the cold reduction ratio is more preferably 93%, further preferably 91%, and most preferably 89%. The cold rolling can be carried out once or twice to obtain the target thickness.

[0079] Then, final annealing is carried out by soaking the cold-rolled sheet at 950 - 1020 °C for 30 - 60 seconds. When the soaking temperature is lower than 950 °C, an appropriate level of grain growth cannot occur, thus it may not be possible to obtain the effect of improved magnetism. When the soaking temperature exceeds 1020 °C, defects such as micro-indentations will increase on the surface, and the grain growth property increases, thus resulting in deteriorated high-frequency iron loss. The lower limit of the soaking temperature is more preferably 955 °C, further preferably 960 °C, and most preferably 965 °C. The upper limit of the soaking temperature is more preferably 1015 °C, further preferably 1010 °C, and most preferably 1005 °C. When the soaking time is less than 30 seconds, the crystal grain size does not grow sufficiently, thus having the drawback of deteriorated magnetism. When the soaking time exceeds 60 seconds, there is the drawback of excessive grain growth. The lower limit of the soaking time is more preferably 32 seconds, further preferably 34 seconds, and most preferably 36 seconds. The upper limit of the soaking time is more preferably 59 seconds, further preferably 58 seconds, and most preferably 57 seconds.

[0080] During the final annealing, the tension on the inlet side of the annealing furnace is 0.5 - 1.0 kgf / mm 2 , and during the heating to the soaking temperature, it is preferable to control the holding time in the range of 600 - 750 °C to be less than 24 seconds. If an appropriate tension is applied on the inlet side of the annealing furnace, it will promote grain boundary segregation, thus improving the magnetism. When the tension on the inlet side of the annealing furnace is less than 0.5 kgf / mm 2 , there is the drawback that it is difficult to control the sheet shift during continuous annealing. When the tension on the inlet side of the annealing furnace exceeds 1.0 kgf / mm 2 , there is the drawback of promoting the formation of a texture that is not conducive to magnetism. The lower limit of the tension on the inlet side of the annealing furnace is more preferably 0.55 kgf / mm 2 , further preferably 0.6 kgf / mm 2 , and most preferably 0.65 kgf / mm 2 . The upper limit of the tension on the inlet side of the annealing furnace is more preferably 0.95 kgf / mm 2, more preferably 0.90 kgf / mm 2 , most preferably 0.85 kgf / mm 2 . The tension on the inlet side of the annealing furnace can be based on the tension applied to the bridle roll. The temperature range of 600 - 750 °C is a temperature range where grain recovery and recrystallization are active. In the present invention, it is preferred to minimize the residence time in this range. Thereby, the texture can be improved by promoting segregation at the grain boundaries. When the holding time exceeds 24 seconds, it is difficult to fully obtain the above effects. The holding time is more preferably 22 seconds or less, and further preferably 20 seconds or less. In the present invention, the shorter the holding time, the more advantageous, so no particular limitation is imposed on its lower limit. However, the lower limit of the holding time can be, for example, 10 seconds. Detailed Description of the Invention

[0081] Hereinafter, the present invention will be described in more detail by way of examples. However, it should be noted that the following examples are only for illustrating the present invention and for more detailed description, rather than for limiting the scope of the rights of the present invention. This is because the scope of the rights of the present invention is determined by the content recorded in the claims and the content reasonably deduced therefrom.

[0082] (Examples)

[0083] A slab (C, N, Ti: 0.003%) having the alloy composition shown in Table 1 below was heated at 1150 °C, and then the heated slab was hot finish rolled at 850 °C to obtain a hot rolled sheet with a thickness of 2.0 mm. Then, the hot rolled sheet was annealed at 1100 °C for 4 minutes and then pickled. Then, the hot rolled sheet was cold rolled at a reduction ratio of 87.5% to obtain a cold rolled sheet with a thickness of 0.25 mm. Then, final annealing was carried out under the conditions shown in Table 2 below to manufacture a non-oriented electrical steel sheet. On the other hand, the conditions shown in Table 2 below are based on the surface temperature of the steel sheet.

[0084] For the non-oriented electrical steel sheet manufactured as described above, the texture (112)[1 - 31] strength and the texture (112)[1 - 10] strength were measured, and the resistivity, iron loss (W10 / 400), and magnetic flux density (B50) were measured, and the results are shown in Table 3 below.

[0085] The texture (112)[1 - 31] strength and the texture (112)[1 - 10] strength were measured using SEM - EBSD.

[0086] The resistivity can be obtained by Equation 1 below.

[0087] [Equation 1] 13.25 + 11.3×([Si] + [Al] + [Mn] / 2)

[0088] The iron loss (W10 / 400) and the magnetic flux density (B50) were measured using a single sheet tester according to the JIS standard.

[0089] [Table 1]

[0090]

[0091] [Table 2]

[0092]

[0093] [Table 3]

[0094]

[0095] As can be seen from Tables 1 to 3 above, in the case of Invention Examples 1 to 11 that satisfy the alloy composition and manufacturing conditions proposed by the present invention, since the texture (112)[1-31] / texture (112)[1-10] strength ratio proposed by the present invention is satisfied, low high-frequency iron loss can be ensured.

[0096] Comparative Examples 1 to 13 are cases where the alloy composition or manufacturing conditions proposed by the present invention are not satisfied. It can be seen that since the texture (112)[1-31] / texture (112)[1-10] strength ratio proposed by the present invention is not satisfied, the high-frequency iron loss is poor.

Claims

1. An non-oriented electrical steel sheet, by weight%, the non-oriented electrical steel sheet comprises: Si: 3.3 - 4.3%, Al: 0.8 - 1.7%, Mn: 0.3 - 2.0%, Cu: 0.03 - 0.5%, Sn: 0.01 - 0.1%, S: 0.002 - 0.01%, the balance Fe and other inevitable impurities, the non-oriented electrical steel sheet satisfies the following relational expression 1, and the texture (112)[1 - 31] / texture (112)[1 - 10] strength ratio is 2.0 or more, [Relational expression 1] 0.02 ≤ Sn × S × 100 / Cu ≤ 0.

75.

2. The non-oriented electrical steel sheet according to claim 1, wherein, the non-oriented electrical steel sheet further comprises one or more of C: 0.005% or less, N: 0.005% or less, Ti: 0.005% or less, Nb: 0.005% or less, and V: 0.005% or less.

3. The non-oriented electrical steel sheet according to claim 1, wherein, the non-oriented electrical steel sheet further comprises one or more of P: 0.1% or less, Cr: 0.01 - 0.5%, Sb: 0.1% or less, Ni: 0.05% or less, and Zn: 0.01% or less.

4. The non-oriented electrical steel sheet according to claim 1, wherein, the non-oriented electrical steel sheet further comprises one or more of Mo: 0.03% or less, B: 0.0050% or less, Ca: 0.005% or less, and Mg: 0.005% or less.

5. The non-oriented electrical steel sheet according to claim 1, wherein, the non-oriented electrical steel sheet further comprises one or more of Bi, Pb, Ge, and As, the contents of Bi, Pb, Ge, and As are each 0.20% or less and excluding 0% or the total amount is 0.20% or less and excluding 0%.

6. The non-oriented electrical steel sheet according to claim 1, wherein, the strength of the texture (112)[1 - 31] of the non-oriented electrical steel sheet is 2.5 or more, and the strength of the texture (112)[1 - 10] is 0.9 or less.

7. The non-oriented electrical steel sheet according to claim 1, wherein, the resistivity of the non-oriented electrical steel sheet is 55 μΩcm or more.

8. The non-oriented electrical steel sheet according to claim 1, wherein, the iron loss (W10 / 400) of the non-oriented electrical steel sheet is 12.2 W / Kg or less.

9. The non-oriented electrical steel sheet according to claim 1, wherein, the magnetic flux density (B50) of the non-oriented electrical steel sheet is 1.66 tesla or more.

10. A method for manufacturing a non-oriented electrical steel sheet, which comprises the following steps: heating a slab at 1100 - 1250 °C, by weight%, the slab comprises: Si: 3.3 - 4.3%, Al: 0.8 - 1.7%, Mn: 0.3 - 2.0%, Cu: 0.03 - 0.5%, Sn: 0.01 - 0.1%, S: 0.002 - 0.01%, the balance Fe and other inevitable impurities, and satisfies the following relational expression 1; hot-rolling the heated slab at 800 - 1000 °C to obtain a hot-rolled sheet; cold-rolling the hot-rolled sheet with a reduction ratio of 70 - 95% to obtain a cold-rolled sheet; and a final annealing step of soaking the cold-rolled sheet at 950 - 1020 °C for 30 - 60 seconds, Among them, during the final annealing, the tension on the inlet side of the annealing furnace is 0.5 - 1.0 kgf / mm 2 , and during the heating to the soaking temperature, the holding time in the range of 600 - 750 °C is controlled to be below 24 seconds. [Relational expression 1] 0.02 ≤ Sn × S × 100 / Cu ≤ 0.

75.

11. The method for manufacturing an non-oriented electrical steel sheet according to claim 10, wherein, The slab further contains one or more of C: 0.005% or less, N: 0.005% or less, Ti: 0.005% or less, Nb: 0.005% or less, and V: 0.005% or less.

12. The manufacturing method of the non-oriented electrical steel sheet according to claim 10, wherein, The slab further contains one or more of P: 0.1% or less, Cr: 0.01 - 0.5%, Sb: 0.1% or less, Ni: 0.05% or less, and Zn: 0.01% or less.

13. The manufacturing method of the non-oriented electrical steel sheet according to claim 10, wherein, The slab further contains one or more of Mo: 0.03% or less, B: 0.0050% or less, Ca: 0.005% or less, and Mg: 0.005% or less.

14. The manufacturing method of the non-oriented electrical steel sheet according to claim 10, wherein, The slab further contains one or more of Bi, Pb, Ge, and As, and the contents of Bi, Pb, Ge, and As are 0.20% or less each, excluding 0%, or the total amount is 0.20% or less, excluding 0%.

15. The manufacturing method of the non-oriented electrical steel sheet according to claim 10, wherein, The manufacturing method further includes the following step: after the step of obtaining the hot-rolled sheet, annealing the hot-rolled sheet at 850 - 1150 °C.

16. The manufacturing method of the non-oriented electrical steel sheet according to claim 10, wherein, The cold rolling is performed once or twice.

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