ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR PREPARING SAME

Abstract

An oriented electrical steel sheet according to an embodiment of the present invention includes, in a unit of wt %, Si at 1.0 wt % to 5.0 wt %, C at 0.005 wt % or less (excluding 0 wt %), Mn at 0.001 wt % to 0.1 wt %, Cu at 0.001 wt % to 0.1 wt %, S at 0.001 wt % to 0.020 wt %, Se at 0.001 wt % to 0.050 wt %, Al at 0.0005 wt % to 0.010 wt %, N at 0.0005 wt % to 0.005 wt %, and the remainder of Fe and inevitable impurities.

The oriented electrical steel sheet according to the embodiment of the present invention satisfies Equation 1.

16≤(10×[Mn]+[Cu])/([S]+[Se])+(0.02−[Al])/[N]≤20  [Equation 1]

(In Equation 1, [Mn], [Cu], [S], [Se], [Al], and [N] represent contents (wt %) of Mn, Cu, S, Se, Al, and N, respectively.)

Claims

1. A preparing method of an oriented electrical steel sheet, comprising: preparing a slab including, in a unit of wt %, Si at 1.0 wt % to 5.0 wt %, C at 0.001 wt % to 0.10 wt %, Mn at 0.001 wt % to 0.1 wt %, Cu at 0.001 wt % to 0.1 wt %, S at 0.001 wt % to 0.020 wt %, Se at 0.001 wt % to 0.050 wt %, Al at 0.0005 wt % to 0.010 wt %, N at 0.0005 wt % to 0.005 wt %, and the remainder of Fe and inevitable impurities, and satisfying Equation 1; heating the slab; hot rolling the slab to prepare a hot rolled sheet; cold rolling the hot rolled sheet to prepare a cold rolled sheet; primary recrystallization annealing the cold rolled sheet; and secondary recrystallization annealing the cold rolled sheet in which the primary recrystallization annealing is completed:
16≤(10×[Mn]+[Cu])/([S]+[Se])+(0.02−[Al])/[N]≤20  [Equation 1] (in Equation 1, [Mn], [Cu], [S], [Se], [Al], and [N] represent contents (wt %) of Mn, Cu, S, Se, Al, and N, respectively.)

2. The preparing method of the oriented electrical steel sheet of claim 1, wherein the heating of the slab includes heating the slab at 1000 to 1250° C.

3. The preparing method of the oriented electrical steel sheet of claim 1, wherein the cold rolled sheet in which the primary recrystallization annealing is completed includes one or more precipitates of (Fe,Mn,Cu)S and (Fe,Mn,Cu)Se.

4. The preparing method of the oriented electrical steel sheet of claim 1, wherein the primary recrystallization annealing is performed in a hydrogen and nitrogen mixed atmosphere at a dew point temperature of 50° C. to 70° C.

Description

MODE FOR INVENTION

[0019] It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers, and/or sections, they are not limited thereto. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Therefore, a first part, component, area, layer, or section to be described below may be referred to as second part, component, area, layer, or section within the range of the present invention.

[0020] The technical terms used herein are to simply mention a particular embodiment and are not meant to limit the present invention. An expression used in the singular encompasses an expression of the plural, unless it has a clearly different meaning in the context. In the specification, it is to be understood that the terms such as “including”, “having”, etc., are intended to indicate the existence of specific features, regions, numbers, stages, operations, elements, components, and/or combinations thereof disclosed in the specification, and are not intended to preclude the possibility that one or more other features, regions, numbers, stages, operations, elements, components, and/or combinations thereof may exist or may be added.

[0021] When referring to a part as being “on” or “above” another part, it may be positioned directly on or above another part, or another part may be interposed therebetween. In contrast, when referring to a part being “directly above” another part, no other part is interposed therebetween.

[0022] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meanings as those generally understood by those with ordinary knowledge in the field of art to which the present invention belongs. Terms defined in commonly used dictionaries are further interpreted as having meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as having idealized or very formal meanings unless defined otherwise.

[0023] Unless otherwise stated, % means % by weight, and 1 ppm is 0.0001% by weight.

[0024] Further, in exemplary embodiments of the present invention, inclusion of an additional element means replacing remaining iron (Fe) by an additional amount of the additional elements.

[0025] The present invention will be described more fully hereinafter, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

[0026] An oriented electrical steel sheet according to an embodiment of the present invention includes, in a unit of wt %, Si at 1.0 wt % to 5.0 wt %, C at 0.005 wt % or less (excluding 0 wt %), Mn at 0.001 wt % to 0.1 wt %, Cu at 0.001 wt % to 0.1 wt %, S at 0.001 wt % to 0.020 wt %, Se at 0.001 wt % to 0.050 wt %, Al at 0.0005 wt % to 0.010 wt %, N at 0.0005 wt % to 0.005 wt %, and the remainder of Fe and inevitable impurities.

[0027] Hereinafter, the reason for limiting the components of the oriented electrical steel sheet will be described.

[0028] Si at 1.0 to 5.0 wt %

[0029] Silicon (Si) increases specific resistance of the oriented electrical steel sheet, and thus serves to decrease core loss, that is, iron loss. When a Si content is excessively small, the specific resistance decreases, eddy current loss increases, and thus the iron loss may deteriorate. In addition, during primary recrystallization annealing, phase transformation between ferrite and austenite occurs, so a primary recrystallized texture may be severely damaged. In addition, phase transformation between ferrite and austenite occurs during secondary recrystallization annealing, thus the second recrystallization may become unstable, and a Goss texture may be severely damaged. When the Si content is excessively large, oxide layers of SiO.sub.2 and Fe.sub.2SiO are excessively and densely formed during decarburization in primary recrystallization annealing, thus decarburization behavior may be delayed. In addition, brittleness of the steel increases, and toughness thereof decreases, so an occurrence rate of plate rupture during a rolling process may be intensified. In addition, weldability between plates may be degraded, making it difficult to secure easy workability. Therefore, Si may be included at 1.0 to 5.0 wt %. Specifically, it may be included at 2.0 to 4.0 wt %.

[0030] C at 0.005 wt % or less

[0031] Carbon (C) is an element that contributes to refining grains and to improve elongation by causing phase transformation between ferrite and austenite. C is an essential element for improving rollability of an electric steel sheet having poor rolling properties due to high brittleness. However, when it remains in a final product, it must be controlled to an appropriate content because it is an element that deteriorates magnetic properties by precipitating carbides formed due to a magnetic aging effect in a product sheet. In the embodiment of the present invention, during the primary recrystallization annealing in the preparing process, a decarburization process is performed, and the C content in the final electrical steel sheet prepared after the decarburization annealing may be 0.005 wt % or less. More specifically, it may be 0.003 wt % or less.

[0032] C of 0.001 to 0.10 wt % may be included in the slab. When the slab contains too little C, phase transformation between austenite does not sufficiently occur, causing unevenness of the slab and the hot-rolled microstructure. As a result, cold rolling properties are also deteriorated. When it contains too much C, sufficient decarburization may not be obtained in a decarburization process. Therefore, due to the phase transformation phenomenon caused by this, the secondary recrystallized texture is severely damaged. Further, when the final product is applied to a power apparatus, it may cause deterioration of magnetic properties due to self-aging. More specifically, C at 0.01 to 0.1 wt % may be included in the slab.

[0033] Mn at 0.001 to 0.1 wt %

[0034] Manganese (Mn) has the effect of reducing the iron loss by increasing the specific resistance, like Si. In addition, it is an important element for forming secondary precipitates as a grain growth inhibitor by forming S- and Se-based precipitates. When a content of Mn is excessively small, a sufficient effect as an inhibitor may not be expected because the amount and volume formed are small. When the content of Mn is excessively large, a large amount of (Fe, Mn) and Mn oxide in addition to Fe.sub.2SiO.sub.4 is formed on a surface of the steel sheet, which inhibits formation of a base coating formed during the secondary recrystallization annealing, thereby lowering surface quality, and in the primary recrystallization annealing process, non-uniformity of phase transformation between ferrite and austenite causes a size of the primary recrystallized grains to be non-uniform, resulting in unstable secondary recrystallization. Therefore, the content of Mn may be limited to 0.001 to 0.10 wt %. Specifically, Mn may be included in an amount of 0.01 to 0.05 wt %.

[0035] Cu at 0.001 to 0.10 wt %

[0036] Copper (Cu) is an important element for forming secondary recrystallization as a grain growth inhibitor by forming S- and Se-based precipitates like Mn. When a Cu content is excessively small, a sufficient effect as an inhibitor may not be expected. In contrast, when the content thereof is excessively large, a decomposition temperature of the precipitate is excessively high, which makes it difficult to control the precipitate. Therefore, the content of Cu may be limited to 0.001 to 0.10 wt %. Specifically, Cu may be included in an amount of 0.01 to 0.07 wt %.

[0037] S at 0.001 to 0.020 wt %

[0038] Sulfur (S) is an important element for forming secondary precipitates as a grain growth inhibitor by forming S- and Se-based precipitates. When a S content is excessively small, an effect of inhibiting grain growth may be deteriorated. When the S content is excessively large, occurrence of edge cracks in continuous casting and hot rolling processes may increase, so that an actual yield may decrease. Therefore, the content of S may be limited to 0.001 to 0.020 wt %. Specifically, S may be included in an amount of 0.007 to 0.015 wt %.

[0039] Se at 0.001 to 0.050 wt %

[0040] Selenium (Se) is an important element for forming secondary precipitates as a grain growth inhibitor by forming S- and Se-based precipitates like S. In the embodiment of the present invention, Se is added in combination with S in order to inhibit edge cracking during slab continuous casting and hot rolling processes due to an excessive S content. When a Se content is excessively small, an effect of inhibiting grain growth may be deteriorated. When the Se content is excessively large, occurrence of edge cracks in continuous casting and hot rolling processes may increase, so that an actual yield may decrease. Therefore, the Se content may be limited to 0.001 to 0.050 wt %. Specifically, Se may be included in an amount of 0.007 to 0.03 wt %.

[0041] Al at 0.0005 to 0.010 wt %

[0042] Aluminum (Al) is combined with nitrogen in the steel to form AlN precipitates. In the present invention, S- and Se-based precipitates are used as a grain growth inhibitor, and insufficient grain growth inhibition is solved by using the AlN precipitates. When an Al content is excessively large, a decomposition temperature of the AlN precipitate becomes excessively high, and the grain growth inhibition ability by the AlN increases, which affects the secondary recrystallization by the S- and Se-based precipitates. When the Al content is excessively small, the grain growth inhibition ability by the AlN precipitate may not be expected. Therefore, the Al content may be limited to 0.0005 to 0.010 wt %. Specifically, Al may be included in an amount of 0.0015 to 0.01 wt %.

[0043] N at 0.0005 to 0.005 wt %

[0044] Nitrogen (N) reacts with Al to form AlN precipitates. For the same reason as Al, a content of N may be limited to 0.0005 to 0.005 wt % in order to not affect secondary recrystallization by S- and Se-based precipitates. Specifically, N may be included in an amount of 0.003 to 0.005 wt %. In the embodiment of the present invention, during the preparing process, a nitriding process is not included, and the slab and the content of N in the final prepared oriented electrical steel sheet may be the same.

[0045] In the embodiment of the present invention, the oriented electrical steel sheet may satisfy Equation 1.

16≤(10×[Mn]+[Cu])/([S]+[Se])+(0.02−[Al])/[N]≤20  [Equation 1]

[0046] (In Equation 1, [Mn], [Cu], [S], [Se], [Al], and [N] represent the contents (wt %) of Mn, Cu, S, Se, Al, and N, respectively.)

[0047] When a value of Equation 1 is excessively small, rolling rupture may occur, or a large amount of S- and Se-based precipitates may be precipitated, thereby deteriorating the magnetic properties. When the value of Equation 1 is excessively large, the S- and Se-based precipitates are not properly formed, and the secondary recrystallized texture is damaged, and the magnetism may deteriorate. Specifically, the value of Equation 1 may be 16.2 to 19.9.

[0048] In the embodiment of the present invention, the oriented electrical steel sheet may satisfy Equation 2.

0.016≤[S]+[Se]≤0.05

[0049] (In Equation 2, [S] and [Se] represent the contents (wt %) of S and Se, respectively.)

[0050] When a value of Equation 2 is excessively small, the S- and Se-based precipitates are not properly formed, the secondary recrystallized texture is damaged, and the magnetism may deteriorate. When the value of Equation 2 is excessively large, a large amount of S- and Se-based precipitates may be precipitated, thereby deteriorating the magnetic properties. Specifically, the value of Equation 2 may be 0.02 to 0.03.

[0051] In the embodiment of the present invention, the oriented electrical steel sheet may satisfy Equation 3.

0.5≤[Al]/[N]≤3.0

[0052] (In Equation 3, [Al] and [N] represent the contents (wt %) of Al and N, respectively.)

[0053] When the value of Equation 3 is excessively small, the grain growth inhibition ability by the AlN may not be expected. When the value of Equation 3 is excessively large, the grain growth inhibition ability by the AlN increases, which affects the secondary recrystallization by the S- and Se-based precipitates. Specifically, the value of Equation 3 may be 0.5 to 2.8.

[0054] Impurity Element

[0055] In addition to the above elements, impurities such as Ni, Zr, and V, which are inevitably added, may be included. In the case of Ni, it reacts with impurity elements to form fine sulfides, carbides, and nitrides, which have a undesirable effect on magnetism, and thus these contents are limited to 0.05 wt % or less, respectively. Since Zr, V, etc. are also elements strongly forming carbonitrides, it is preferable that they are added as little as possible, and they are contained in an amount of 0.01 wt % or less, respectively.

[0056] In the embodiment of the present invention, by controlling the correlation between Mn, Cu, S, Se, Al, and N in the alloy component, magnetic properties may be further improved. Specifically, in a thickness standard of 0.30 mm, the iron loss in a condition of 1.7 Tesla and 50 Hz of the oriented electrical steel sheet may be 1.5 W/kg or less. More specifically, in the thickness standard of 0.30 mm, the iron loss in the condition of 1.7 Tesla and 50 Hz of the oriented electrical steel sheet may be 0.9 to 1.1 W/kg. A magnetic flux density B8 induced under the magnetic field of 800 A/m of the oriented electrical steel sheet may be 1.88 T or more. Specifically, it may be 1.88 to 1.95 T. When the magnetic flux density B8 is 1.88 T or more, there is an advantage of high transformer efficiency and low noise.

[0057] A preparing method of an oriented electrical steel sheet according to an embodiment of the present invention includes: preparing a slab; heating the slab; hot rolling the slab to prepare a hot rolled sheet; cold rolling the hot rolled sheet to prepare a cold rolled sheet; primary recrystallization annealing the cold rolled sheet; and secondary recrystallization annealing the cold rolled sheet in which the primary recrystallization annealing is completed.

[0058] Hereinafter, each step will be described in detail.

[0059] First, a slab is prepared.

[0060] In a steel making process, Si, C, Mn, Cu, S, Se, Al, and N may be controlled to an appropriate amount, and alloy elements, which are advantageous for forming a Goss texture, may be added as necessary. Molten steel whose components have been adjusted in the steel making process is prepared into a slab through continuous casting.

[0061] Each composition of the slab has been described in detail in the above-described oriented electrical steel sheet, so a duplicate description thereof is omitted. Equations 1 to 3 described above may be identically satisfied even in an alloy component of the slab.

[0062] Next, the slab is heated.

[0063] The heating of the slab is preferably performed at a low temperature of 1250° C. or less, more preferably 1150° C. or less, so that the precipitates are partially solvated. This is because, when the slab heating temperature is increased, a surface of the slab is melted, and thus it is required that a heating furnace is repaired and life of the heating furnace may be shortened. In addition, when the slab is heated at a temperature of 1250° C. or lower, and more preferably 1150° C. or lower, it is prevented that a columnar structure of the slab is coarsely grown, thereby preventing cracks from occurring in a width direction of the sheet in a subsequent hot-rolling process to improve an actual yield. When the temperature is less than 1000° C., the hot rolling temperature is low, so that deformation resistance of the steel sheet increases, which increases a rolling load. Therefore, the slab heating temperature may be 1000° C. to 1250° C.

[0064] Next, a hot rolled sheet is prepared by hot rolling the slab. A hot rolled sheet having a thickness of 1.5 to 4.0 mm may be prepared by the hot rolling.

[0065] The hot-rolled hot rolled sheet may be subjected to hot rolled sheet annealing or may be subjected to cold rolling without performing hot rolled sheet annealing, as necessary. In the case of performing the hot rolled sheet annealing, in order to make a hot-rolled structure uniform, it may be heated to a temperature of 900° C. or higher, and then cooled.

[0066] Next, a cold rolled sheet is prepared by cold rolling the hot rolled sheet. The cold rolling is performed by using a reverse mill or a tandem mill by cold rolling once or two times or more including intermediate annealing to prepare a cold rolled sheet having a final product thickness. It is advantageous to improve the magnetic property to perform warm rolling that maintains a temperature of the steel sheet at 100° C. or higher during the cold rolling.

[0067] Next, the cold-rolled cold rolled sheet is subjected to primary recrystallization annealing. In the primary recrystallization annealing process, primary recrystallization occurs in which nuclei of Goss grains are generated. In the primary recrystallization annealing process, decarburization of the steel sheet may be performed. For the decarburization, it may be performed in a dew point temperature of 50° C. to 70° C. and a mixed atmosphere of hydrogen and nitrogen. The primary recrystallization annealing temperature may be 800 to 950° C. When the annealing temperature is low, decarburization may take a long time. When the annealing temperature is high, the primary recrystallized grains grow coarse, and grain growth driving force is lowered, so that stable secondary recrystallization is not formed. In addition, an annealing time is not a big problem for the effect of the present invention, but may be set within 5 minutes in consideration of productivity. In the embodiment of the present invention, only decarburization is performed, and nitriding may not be performed. That is, the primary recrystallization annealing may be performed only at a dew point temperature of 50° C. to 70° C. and a mixed atmosphere of hydrogen and nitrogen.

[0068] The cold rolled sheet subjected to the primary recrystallization annealing includes S- and Se-based precipitates, and is used as a grain growth inhibitor during secondary recrystallization annealing. Specifically, the S- and Se-based precipitates may include one or more precipitates of (Fe,Mn,Cu)S and (Fe,Mn,Cu)Se. (Fe,Mn,Cu)S means a precipitate in which one or more of S, Fe, Mn, and Cu are combined.

[0069] Next, the cold rolled sheet in which the primary recrystallization annealing is completed is subjected to the secondary recrystallization annealing. In this process, a Goss {110}<001> texture is formed in which a {110} plane is parallel to the rolling plane and a <001> direction is parallel to the rolling direction. In this case, after an annealing separator is applied to the cold rolled sheet in which the primary recrystallization annealing is completed, the secondary recrystallization annealing may be performed. In this case, the annealing separator is not particularly limited, and an annealing separator containing MgO as a main component may be used.

[0070] In the secondary recrystallization annealing, a temperature is raised at an appropriate heating rate to form the second recrystallization of a {110}<001> Goss orientation, and then, after purification annealing, which is an impurity removal process, it is cooled. In the process, an annealing atmosphere gas is heat-treated using a mixed gas of hydrogen and nitrogen during the temperature rising process as in the general case, and 100% hydrogen gas is used in the purification annealing for a long time to remove impurities.

[0071] Hereinafter, preferred examples of the present invention and comparative examples will be described. However, the following examples are only preferred examples of the present invention, and the present invention is not limited to the following examples.

EXAMPLES

[0072] A slab including Si at 3.2 wt %, C at 0.055 wt %, and the contents of Mn, Cu, S, Se, Al, and N that were changed as shown in Table 1, and a remainder Fe and inevitable impurities was prepared. Subsequently, the slab was heated to 1250° C. and then hot rolled to prepare a 2.3 mm thick hot rolled sheet. The hot rolled sheet was heated at a temperature of 1085° C., then maintained at 910° C. for 160 seconds and quenched in water. Next, after pickling the hot-rolled annealing sheet, it was cold-rolled to a thickness of 0.30 mm, and the primary recrystallization annealing was performed for the cold-rolled steel sheet by maintaining it at a temperature of 850° C. for 180 seconds in a mixed gas atmosphere of hydrogen and nitrogen at a dew point of 60° C. After applying MgO, which is an annealing separator, to this steel sheet, the secondary recrystallization annealing was performed therefor, wherein the secondary recrystallization annealing was performed in a mixed gas atmosphere of “25 v % nitrogen+75 v % hydrogen” up to 1200° C. and in a gas atmosphere of 100 v % hydrogen after reaching 1200° C. for 10 hours or more, and then was furnace-cooled. Table 1 shows the magnetic properties of the oriented electrical steel sheet according to each component.

[0073] The iron loss was measured under the condition of 1.7 Tesla and 50 Hz using a single sheet measurement method, and the magnetic flux density (Tesla) induced under the magnetic field of 800 Nm was measured. Each iron loss value was an average of each condition.

TABLE-US-00001 TABLE 1 Mn Cu S Se Al N Classification (wt %) (wt %) (wt %) (wt %) (wt %) (wt %) Comparative 0.025 0.01 0.024 0.005 0.002 0.0038 Example 1 Comparative 0.025 0.01 0.003 0.059 0.0018 0.0039 Example 2 Comparative 0.024 0.011 0.003 0.006 0.0017 0.0035 Example 3 Comparative 0.025 0.01 0.007 0.008 0.0018 0.0038 Example 4 Inventive 0.025 0.012 0.01 0.011 0.0018 0.0035 Example 1 Inventive 0.025 0.031 0.01 0.01 0.002 0.0033 Example 2 Inventive 0.024 0.05 0.011 0.009 0.0017 0.0034 Example 3 Comparative 0.025 0.072 0.01 0.011 0.0015 0.0036 Example 5 Comparative 0.026 0.089 0.01 0.01 0.0016 0.0035 Example 6 Inventive 0.025 0.01 0.01 0.012 0.0051 0.0034 Example 4 Inventive 0.026 0.012 0.01 0.01 0.0098 0.0036 Example 5 Comparative 0.025 0.011 0.01 0.011 0.013 0.0037 Example 7 Inventive 0.036 0.011 0.01 0.015 0.01 0.0045 Example 6 Inventive 0.036 0.032 0.008 0.016 0.008 0.0043 Example 7 Inventive 0.036 0.052 0.009 0.016 0.007 0.0044 Example 8 Comparative 0.036 0.072 0.009 0.014 0.007 0.0045 Example 8 Comparative 0.036 0.104 0.009 0.015 0.008 0.0043 Example 9 Inventive 0.035 0.012 0.01 0.016 0.0019 0.0034 Example 9 Inventive 0.034 0.01 0.012 0.012 0.0066 0.0035 Example 10 Comparative 0.049 0.01 0.01 0.018 0.002 0.0038 Example 10 Comparative 0.05 0.011 0.018 0.041 0.0017 0.0035 Example 11

TABLE-US-00002 TABLE 2 Equa- Equa- Equa- Magnetic flux Iron loss Classifica- tion 1 tion 2 tion 3 density (B8, (W17/50, tion value value value Tesla) W/kg) Comparative 13.7 0.029 0.526 Rolling crack Example 1 Comparative 8.86 0.062 0.462 Rolling crack Example 2 Comparative 33.12 0.009 0.486 1.48 2.39 Example 3 Comparative 22.12 0.015 0.474 1.83 1.23 Example 4 Inventive 17.68 0.021 0.514 1.94 0.91 Example 1 Inventive 19.5 0.02 0.606 1.92 0.95 Example 2 Inventive 19.88 0.02 0.5 1.91 0.96 Example 3 Comparative 20.47 0.021 0.417 1.85 1.17 Example 5 Comparative 22.71 0.02 0.457 1.82 1.27 Example 6 Inventive 16.2 0.022 1.5 1.92 0.96 Example 4 Inventive 16.43 0.02 2.722 1.9 0.98 Example 5 Comparative 14.32 0.021 3.514 1.86 1.15 Example 7 Inventive 17.06 0.025 2.222 1.88 1.03 Example 6 Inventive 19.12 0.024 1.86 1.9 0.99 Example 7 Inventive 19.43 0.025 1.591 1.92 0.96 Example 8 Comparative 21.67 0.023 1.556 1.68 1.80 Example 8 Comparative 22.12 0.024 1.86 1.71 1.71 Example 9 Inventive 19.25 0.026 0.559 1.88 1.03 Example 9 Inventive 18.41 0.024 1.886 1.91 0.97 Example 10 Comparative 22.59 0.028 0.526 1.47 2.48 Example 10 Comparative 13.89 0.059 0.486 1.48 2.45 Example 11

[0074] As can be seen in Table 1 and Table 2, it can be confirmed that the magnetic flux density and the iron loss was excellent in the inventive examples satisfying Equation 1 by controlling the Mn, Cu, S, Se, Al, and N contents.

[0075] In contrast, in the comparative example that did not satisfy Equation 1, it can be confirmed that the edge crack occurred or the magnetic flux density and iron loss were deteriorated.

[0076] The present invention may be embodied in many different forms, and should not be construed as being limited to the disclosed embodiments. In addition, it will be understood by those skilled in the art that various changes in form and details may be made thereto without departing from the technical spirit and essential features of the present invention. Therefore, it is to be understood that the above-described exemplary embodiments are for illustrative purposes only, and the scope of the present invention is not limited thereto.