KR101701195B1 - Non-oriented electrical steel sheet and method for manufacturing the same - Google Patents

Abstract

According to an embodiment of the present invention, provided is a non-oriented electrical steel sheet which has excellent magnetism and high productivity. The non-oriented electrical steel sheet comprises: 0.5-4 wt% of Si, 0.4-2.0 wt% of Mn, 0.002-0.2 wt% of P, 0.001-0.005 wt% of S, 0.1 wt% or less of Al (excluding 0 wt%), 0.005 wt% or less of N (excluding 0 wt%), 0.005 wt% or less of Ti (excluding 0 wt%), 0.002-0.2 wt% of Sn, and the remainder consisting of Fe and inevitable impurities. The non-oriented electrical steel sheet satisfies formula 1 and the number of sulfide with a diameter of 10-500 nm is 1.05/m^2. [Formula 1] 0.1 <= [Mn] / ([Si] + 10 [Al]) <= 0.6 (In formula 1; [Mn], [Si] and [Al] represent content of Mn, Si, and Al).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a non-oriented electrical steel sheet,

A non-oriented electrical steel sheet and a manufacturing method thereof.

The nonoriented electrical steel sheet is used as an iron core material in rotating equipment such as motors, generators, and stationary equipment such as small transformers, and it transforms electrical energy into mechanical energy. Since energy saving is emerging as a social issue, it is necessary to improve the characteristics of non-oriented electric steel sheet, which is a very important material for determining the energy efficiency of electric devices.

The iron loss and magnetic flux density are the typical magnetic properties of the non-oriented electrical steel sheet, and the iron loss is the energy lost. Therefore, the lower the magnetic loss and the higher the magnetic flux density, the more magnetic field can be induced with the same energy. In order to obtain the same magnetic flux density, The higher the better, because it can reduce the hands.

The essential alloying elements which are importantly added to the non-oriented electrical steel sheet include Si, Al and Mn. Si, Al, and Mn are alloying elements with high resistivity and are added to improve iron loss, which is an important magnetic property of nonoriented electrical steel sheet. However, the addition of Si, Al, Mn, and other alloying elements with high resistivity reduces the iron loss, but it can not avoid reduction of the magnetic flux density due to the decrease of the saturation magnetic flux density. Therefore, the magnetic flux density is also low in the case of the non- . As described above, the problem of improving the magnetic flux density while lowering the iron loss is a difficult part.

Therefore, in order to improve the magnetic flux density while lowering the iron loss, a technique of introducing additional manufacturing processes such as improving the magnetic properties by improving the texture by using special additional elements such as REM or annealing twice twice of rolling is used. However, all of these technologies cause a rise in manufacturing costs and difficulties in mass production, so it is necessary to develop a technology that can improve productivity while exhibiting excellent magnetic characteristics.

There have been continuous efforts to solve these problems and many technologies have been developed. As a method for developing a non-oriented electrical steel sheet having a high magnetic flux density, hot rolling is carried out at a temperature of A3 or higher. When cooling after hot rolling, the cooling rate from A3 temperature to 200 ° C is 50 ° C / s for better magnetic properties, s, annealing the hot-rolled sheet, cold rolling and annealing the cold-rolled sheet. However, there is a disadvantage in that the additional cost is required to control the cooling rate.

In order to manufacture a non-oriented electrical steel sheet having excellent magnetic properties in the rolling direction, a skin pass rolling is performed at a rolling reduction of 3 to 10% in addition to the processes of hot rolling, hot rolling annealing, cold rolling and cold rolling annealing, Respectively. This also has the problem of cost increase due to the additional process.

In order to improve the magnetic properties by improving the texture, the composition weight ratio (MnO / SiO ₂ ) of MnO and SiO ₂ in the oxide inclusions in the steel is set to 0.43 or less. In the hot rolling, the finishing rolling is performed under a condition that the friction coefficient between steel and roll is 0.2 A method of annealing a hot-rolled sheet, annealing a cold-rolled sheet, and annealing a cold-rolled sheet after a finishing rolling temperature of 700 ° C or more is proposed. In this case, since the hot-rolled sheet must be controlled to a thickness of 1.0 mm or less, .

In order to improve the magnetic properties, the method of annealing twice twice including intermediate annealing as the hot-rolled steel sheet has been proposed, but the productivity is decreased and the manufacturing cost is increased.
BACKGROUND ART Open Patent Publication No. 10-2008-0027913

An embodiment of the present invention is to provide a non-oriented electrical steel sheet having excellent magnetic properties and high productivity without precisely controlling the content of Si, Al, and Mn in the steel additive components and without annealing the hot-rolled steel sheet.

Another embodiment of the present invention is to provide a method for manufacturing a non-oriented electrical steel sheet.

The non-oriented electrical steel sheet according to one embodiment of the present invention may contain 0.005% or less (excluding 0%) of C, 0.5 to 4% of Si, 0.4 to 2.0% of Mn, 0.002 to 0.2% of P, S: 0.001 to 0.005%, Al: not more than 0.1% (excluding 0%), N: not more than 0.005% (excluding 0%), Ti: not more than 0.005% (excluding 0% 0.2%, and the balance contains Fe and unavoidable impurities, and the number of sulfides having a particle diameter of 10 to 500 nm is 1.05 / 탆 ² or less, which satisfies the following formula (1).

[Formula 1]

0.1? [Mn] / ([Si] + 10 x [Al])? 0.6

(Where, [Mn], [Si] and [Al] in the formula 1 represent the contents of Mn, Si and Al, respectively)

The average grain size may be 30 to 100 mu m.

Cu, Ni and Cr in an amount of 0.05 wt% or less (excluding 0 wt%), respectively.

Zr, Mo, and V in an amount of 0.01 wt% or less (excluding 0 wt%), respectively.

_Iron loss (W _15/50 ) of 3.5 W / kg or less, and magnetic flux density (B ₅₀ ) of 1.75 T or more.

A method for producing a non-oriented electrical steel sheet according to an embodiment of the present invention includes: 0.005% or less (excluding 0%) of C, 0.5 to 4% of Si, 0.4 to 2.0% of Mn, 0.002 (Excluding 0%), N: 0.005% or less (excluding 0%), Ti: 0.005% or less (excluding 0%), and Sn : 0.002 to 0.2%, the balance comprising Fe and unavoidable impurities, and heating the slab satisfying the following formula (1) and then hot rolling to produce a hot rolled steel sheet; Winding the hot rolled sheet; Cold rolling the rolled hot rolled sheet directly to produce a cold rolled sheet; And recrystallization annealing the cold-rolled sheet, wherein the slab heating temperature (SRT) satisfies the following formula (2), and the slab heating is performed in austenite single phase.

[Formula 1]

0.1? [Mn] / ([Si] + 10 x [Al])? 0.6

 [Formula 2]

[SRT]? [T _MnS ] -30

(SRT) is the slab heating temperature (占 폚), and [T _MnS ] represents the content of _MnS in the formula (1) and the formula (2) It shows the thermodynamic equilibrium precipitation temperature (℃).)

During hot rolling, finish rolling in finish rolling can be terminated on ferrite.

At the step of winding the hot rolled sheet, it can be rolled at a temperature of 600 to 700 캜.

In the step of recrystallization annealing, the cracking temperature may be 900 to 1100 占 폚.

The slab may further contain 0.05 wt% or less (excluding 0 wt%) of Cu, Ni and Cr, respectively.

The slab may further contain Zr, Mo and V in an amount of 0.01 wt% or less (excluding 0 wt%), respectively.

The produced non-oriented electrical steel sheet may have a number of sulfides having a particle diameter of 10 to 500 nm of 1.05 / 탆 ² or less.

The non-oriented electrical steel sheet produced may have an average grain size of 30 to 100 탆.

The non-oriented electrical steel sheet according to an embodiment of the present invention has excellent magnetic characteristics and excellent productivity.

The terms first, second and third, etc. are used to describe various portions, components, regions, layers and / or sections, but are not limited thereto. These terms are only used to distinguish any moiety, element, region, layer or section from another moiety, moiety, region, layer or section. Thus, a first portion, component, region, layer or section described below may be referred to as a second portion, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified and that the presence or absence of other features, regions, integers, steps, operations, elements, and / It does not exclude addition.

When referring to a portion as being "on" or "on" another portion, it may be directly on or over another portion, or may involve another portion therebetween. In contrast, when referring to a part being "directly above" another part, no other part is interposed therebetween.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

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

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

An embodiment of the present invention is to provide a non-oriented electrical steel sheet having excellent productivity and magnetic properties by controlling the components of Si, Mn, and Al among the alloying elements of the steel and controlling the grain size of the crystal grains at the same time.

The non-oriented electrical steel sheet according to one embodiment of the present invention may contain 0.005% or less (excluding 0%) of C, 0.5 to 4% of Si, 0.4 to 2.0% of Mn, 0.002 to 0.2% of P, S: 0.001 to 0.005%, Al: not more than 0.1% (excluding 0%), N: not more than 0.005% (excluding 0%), Ti: not more than 0.005% (excluding 0% 0.2%, the remainder comprising Fe and unavoidable impurities.

First, the reason for limiting the components of the non-oriented electrical steel sheet will be described.

C: 0.005 wt% or less

Carbon (C) is combined with Ti to form carbide to dislocate magnetism. Since it increases iron loss by magnetic aging when it is used as an electrical product in the final product, it is made to be 0.005 wt% or less.

Si: 0.5 to 4.0 wt%

Silicon (Si) is a major element added to increase the resistivity of the steel and to reduce vortex loss during iron loss. In order to obtain low core loss properties, it should be added in an amount of 0.5 wt% or more. On the other hand, as the addition amount is increased, the magnetic flux density is decreased. Therefore, it is difficult to obtain the characteristics of the high magnetic flux density as the addition amount is increased. When the Si is added in an amount exceeding 4% by weight, the magnetic flux density becomes low and commercial production is difficult. By weight to 4% by weight or less.

Mn: 0.4 to 2.0 wt%

Manganese (Mn) is an element that lowers iron loss by increasing resistivity along with Si and Al, and is an austenite stabilizing element unlike Si and Al, which influences the phase transformation behavior. When it is added too much, the magnetic flux density is greatly reduced, so that the addition amount is limited to 0.4 to 2.0 wt%.

P: 0.002 to 0.2 wt%

Phosphorus (P) plays a role of lowering the iron loss by increasing the resistivity and segregating at grain boundaries and improving the texture. It is necessary to add at least 0.002% by weight in order to increase the effect of addition, and when it is added excessively, crystal grain growth is suppressed and cold rolling property is also weakened, so it is added in the range of 0.002 to 0.2% by weight.

S: 0.001 to 0.005 wt%

Sulfur (S) is an element which forms sulfides such as MnS, CuS and (Cu, Mn) S harmful to the magnetic properties, and therefore it is preferable to add as low as possible. However, when it is added in an amount of less than 0.001% by weight, it is rather disadvantageous to the formation of aggregate structure and the magnetic property is deteriorated. If it is added in an amount of more than 0.005% by weight, the magnetism tends to be heated due to the increase of fine sulfides, so that it is contained in an amount of 0.001 to 0.005% by weight.

Al: 0.1 wt% or less

Aluminum (Al) is added because it increases the resistivity and reduces the iron loss, and also reduces the magnetic anisotropy and reduces the magnetization deviation in the rolling direction and in the direction perpendicular to the rolling direction. However, as the addition amount is increased, the magnetic flux density is greatly reduced, so that the addition amount is limited to 0.1 wt% or less.

N: 0.005 wt% or less

Nitrogen (N) is an element harmful to magnetism such as nitrides formed by binding strongly with Al and Ti to inhibit crystal growth, and therefore it is preferable to contain N in an amount as small as 0.005 wt% or less.

Ti: 0.005 wt% or less

Titanium (Ti) forms fine carbides and nitrides to inhibit crystal growth. As the amount of titanium (Ti) increases, the magnetization deteriorates due to increased carbides and nitrides.

Sn: 0.002 to 0.2 wt%

Tin (Sn) is a grain boundary element that suppresses the diffusion of nitrogen through grain boundaries and inhibits the formation of {111}, {112} texture that is harmful to magnetism and increases {100} and {110} In order to improve the magnetic properties, the amount of Sn added is preferably 0.002 to 0.2% by weight, more preferably 0.002 to 0.2% by weight to increase the effect of addition, By weight.

Sb which is a grain boundary segregation element may be further added and may be added so that the sum of the amounts of Sn and Sb added is 0.002 to 0.2% by weight.

Other impurities

In addition to the above-mentioned elements, Cu, Ni, and Cr, which are inevitably added in steelmaking processes, react with impurity elements to form fine sulfides, carbides, and nitrides, thereby detrimentally affecting the magnetic properties. . Further, since Zr, Mo and V are strong carbonitride-forming elements, they are preferably not added as much as possible, and each is contained in an amount of 0.01% by weight or less.

The non-oriented electrical steel sheet according to one embodiment of the present invention satisfies the following formula (1).

[Formula 1]

0.1? [Mn] / ([Si] + 10 x [Al])? 0.6

([Mn], [Si] and [Al] in the formula 1 represent contents of Mn, Si and Al, respectively.

Si, Mn and Al both have an effect of reducing iron loss and reducing magnetic flux density. However, the effects of Si and Al are larger than those of Si and Al because the effect is larger than that of Si and Al. In the case of Mn, it is necessary to control the proper amount of addition because the effect is smaller than that of Si and Al. Therefore, it is necessary to limit the above.

In one embodiment of the present invention, slab heating must occur in the austenite region in order to exhibit excellent magnetic properties without undergoing a hot-rolled sheet annealing process. For this purpose, Si and Al are ferrite stabilizing elements and Mn is an austenite stabilizing element, so that it is necessary to control the added amount properly. When the above-mentioned formula 1 is satisfied, excellent magnetism can be exhibited even without annealing the hot-rolled sheet.

When the hot-rolled sheet is not annealed, the material properties of the hot-rolled sheet are connected to the final product. Therefore, it is necessary to control the grain size and the distribution of the sulfide and the microstructure of the hot-rolled sheet to be advantageous for magnetism. Therefore, the grain size of the sulfide is increased and the number of sulfides of 10 to 500 nm in diameter is 1.05 / 탆 ² or less in the finally produced nonoriented electrical steel sheet, thereby remarkably improving the iron loss and magnetic flux density without going through the annealing process of the hot- .

The non-oriented electrical steel sheet according to an embodiment of the present invention has an average grain size of 30 to 100 탆. The iron loss and magnetic flux density are excellent in the above-mentioned range. Specifically, the iron loss (W15 / 50) may be 3.5 W / kg or less and the magnetic flux density (B50) may be 1.75 T or more.

A method for producing a non-oriented electrical steel sheet according to an embodiment of the present invention includes: 0.005% or less (excluding 0%) of C, 0.5 to 4% of Si, 0.4 to 2.0% of Mn, 0.002 (Excluding 0%), N: 0.005% or less (excluding 0%), Ti: 0.005% or less (excluding 0%), and Sn : 0.002 to 0.2%, the balance comprising Fe and unavoidable impurities, and heating the slab satisfying the following formula (1) and then hot rolling to produce a hot rolled steel sheet; Winding the hot rolled sheet; Cold rolling the rolled hot rolled sheet directly to produce a cold rolled sheet; And recrystallization annealing the cold-rolled sheet.

The slab heating temperature (SRT) satisfies the following formula (2), and the slab heating is performed in the austenite single phase.

[Formula 1]

0.1? [Mn] / ([Si] + 10 x [Al])? 0.6

 [Formula 2]

[SRT]? [T _MnS ] -30

(SRT) is the slab heating temperature (占 폚), and [T _MnS ] represents the content of _MnS in the formula (1) and the formula (2) It shows the thermodynamic equilibrium precipitation temperature (℃).)

Generally, in order to improve the magnetic properties, the hot-rolled sheet is annealed after the hot-rolling. The annealing process of the hot-rolled sheet involves a great deal of cost. Therefore, if the annealed sheet is not used, the manufacturing cost can be greatly reduced. . As in the embodiment of the present invention, when the steel sheet is directly subjected to cold rolling without passing through the hot-rolled sheet annealing step, the hot-rolled sheet is directly cold-rolled and annealed, so that the material properties of the hot-

The heating temperature (SRT) of the slab needs to satisfy the above-described formula (2). When the hot-rolled sheet is not annealed, the material properties of the hot-rolled sheet are connected to the final product. Therefore, it is necessary to control the grain size and the distribution of the sulfide and the microstructure of the hot-rolled sheet to be advantageous for magnetism. Therefore, when the slab is heated under the condition of Equation 2 and heated in a single-phase austenite, the recrystallization fraction of the hot-rolled sheet is also increased, and the grain size of the sulfide is also increased to remarkably improve the iron loss and magnetic flux density, An electric steel sheet can be obtained.

Specifically, the non-oriented electrical steel sheet to be finally produced satisfies the number of sulfides having a grain size of 10 to 500 nm of 1.05 / 탆 ² or less, the average grain size of 30 to 100 탆, the iron loss (W _15/50 ) of 3.5 W / Kg and a magnetic flux density (B ₅₀ ) of 1.75 T or more, which is excellent in magnetic properties, can be obtained.

Hereinafter, each process will be described in detail.

First, the slab is heated and hot-rolled to produce a hot-rolled sheet. The reason why the addition ratio of each composition is limited is the same as the reason for limiting the composition of the non-oriented electrical steel sheet described above. The composition of the slab is substantially the same as that of the non-oriented electrical steel sheet because the composition of the slab is substantially unchanged in the processes of hot-rolled sheet winding, cold rolling and recrystallization annealing described below.

The slab is charged into a furnace and heated in the austenite single phase region. At this time, the slab heating temperature satisfies the above-described expression (2).

The heated slab is hot-rolled to 2 to 2.3 mm to produce a hot-rolled sheet. Finishing rolling in hot rolling is finished in ferrite and final rolling reduction can be carried out at 20% or less for plate shape calibrating.

Next, the hot rolled sheet is wound. Specifically, it is rolled at 600 to 700 ° C and cooled in air.

Next, the wound hot-rolled sheet is immediately cold-rolled to produce a cold-rolled sheet. In this case, the meaning immediately means cold rolling without any intermediate process such as annealing of the rolled hot rolled sheet. The cold rolling can be finally rolled to a thickness of 0.10 mm to 0.70 mm.

The final cold-rolled cold-rolled sheet is subjected to final recrystallization annealing. The cracking temperature at the annealing temperature of recrystallization may be 900 to 1100 캜. When the cracking temperature is less than 900 캜, the growth of the crystal grains is insufficient, and when it exceeds 1100 캜, the crystal grains are excessively grown, which may adversely affect the magnetism. Therefore, the crack temperature can be controlled within the above-mentioned range.

The recrystallized annealed sheet is treated with insulation coating and shipped to the customer. The insulating coating can be treated with an organic, inorganic or organic composite coating, and other insulating coatings can be used. The customer can use this steel sheet as it is and can use it after stress relieving annealing if necessary.

Hereinafter, the present invention will be described in more detail with reference to examples. However, these embodiments are only for illustrating the present invention, and the present invention is not limited thereto.

Example  One

The slabs prepared as shown in Table 1 were heated to the temperatures listed in Table 2, and hot rolled to produce hot rolled sheets having a thickness of 2.6 mm. The hot-rolled steel sheet taken up in the air and cooled was subjected to cold rolling at a thickness of 0.50 mm without annealing the hot-rolled sheet, and recrystallization annealing was performed at 1000 ° C for 100 seconds. For each sample, were calculated the thermodynamic equilibrium phase fraction and the precipitation temperature of sulfide by using a commercially available thermodynamics program, the particle size and distribution of the sulfides was measured using the TEM iron loss (W _15/50), the magnetic flux density (B ₅₀ ). The results are shown in Table 2 below.

_Iron loss (W _15/50 ) is the average loss (W / kg) in the rolling direction and in the rolling direction perpendicular to the magnetic flux density of 1.5 Tesla at 50 Hz frequency. The magnetic flux density (B ₅₀ ) is the magnitude of the magnetic flux density (Tesla) induced when a magnetic field of 5000 A / m is added.

Steel grade C Si Mn P S Al N Ti Sn A1 0.0015 0.8 0.4 0.07 0.0013 0.04 0.0028 0.0009 0.03 A2 0.0014 1.3 0.5 0.09 0.0030 0.09 0.0015 0.0033 0.02 A3 0.0010 0.7 0.3 0.04 0.0029 0.04 0.0014 0.0026 0.09 A4 0.0038 1.8 0.5 0.03 0.0035 0.18 0.0022 0.0017 0.07 A5 0.0025 1.5 0.8 0.06 0.0040 0.05 0.0023 0.0014 0.02 A6 0.0030 2.1 0.8 0.02 0.0015 0.06 0.0037 0.0027 0.01 A7 0.0041 1.6 0.6 0.05 0.0026 0.09 0.0029 0.0016 0.08 A8 0.0007 2.2 0.2 0.08 0.0015 0.02 0.0036 0.0025 0.06 A9 0.0034 1.9 1.1 0.01 0.0017 0.09 0.0014 0.0014 0.09 A10 0.0019 1.4 0.6 0.02 0.0007 0.3 0.0013 0.0032 0.07 A11 0.0033 2.3 1.5 0.03 0.0014 0.08 0.0030 0.0041 0.03 A12 0.0027 1.2 1.1 0.02 0.0011 0.04 0.0022 0.0027 0.10 A13 0.0015 2.5 One 0.02 0.0012 0.03 0.0024 0.0034 0.12

Steel grade Mn / (Si + 10 * Al) Slab heating temperature (℃) Austenite fraction (%) during slab heating T _MnS (MnS equilibrium precipitation temperature, 占 폚) Sulfide number
(Pieces / μm ² ) Iron loss W15 / 50 Magnetic flux density B50 Remarks A1 0.33 1180 100 1289 0.83 3.11 1.76 Honor A2 0.23 1150 100 1293 0.62 2.95 1.75 Honor A3 0.27 1250 100 1268 1.34 5.92 1.69 Comparative Example A4 0.14 1180 28 1271 0.96 4.95 1.67 Comparative Example A5 0.40 1210 100 1335 0.84 2.82 1.75 Honor A6 0.30 1200 100 1286 0.79 2.66 1.72 Honor A7 0.24 1160 100 1297 1.01 2.7 1.73 Honor A8 0.08 1120 0 1151 1.25 4.43 1.67 Comparative Example A9 0.39 1130 100 1316 0.37 2.61 1.72 Honor A10 0.14 1230 100 1210 1.28 4.85 1.67 Comparative Example A11 0.48 1230 100 1340 0.93 2.54 1.71 Honor A12 0.69 1210 100 1374 1.03 4.91 1.68 Comparative Example A13 0.36 1260 78 1283 1.19 4.15 1.66 Comparative Example

As shown in Table 2, when the slab heating is controlled to be performed in the austenite single-phase region in the hot rolling while satisfying [Si], [Mn], [Al] and the formula 1 and the slab heating temperature (SRT) a control to A1, A2, A5, A6, A7, A9, A11 satisfies 10 to 1.05 the number of sulfides in the 500nm particle size dog / ㎛ ² or less in the final product sheet, and as a result the iron loss W _15/50 and magnetic flux density B ₅₀ was superior.

On the other hand, A3 satisfies the control range and formula 1 of Si, Mn, and Al respectively, and satisfies that the slab heating is carried out in the austenite single phase but does not satisfy the formula 2. In the final product plate, And the number of teeth was less than 1.05 / 탆 ² , so that iron loss and magnetic flux density were inferior.

In the case of A4, Al does not satisfy the control range, and the slab heating temperature satisfies Equation 2, but not in the austenite single phase. As a result, iron loss and magnetic flux density are inferior.

A8 did not satisfy the control range of Mn, did not satisfy the formula 1, and the slab heating temperature satisfied the formula 2 but could not be performed in the austenite single phase. As a result, the iron loss and the magnetic flux density were inferior.

A10 does not satisfy the control range of S and Al, and the slab heating temperature does not satisfy the formula 2. In the final product plate, the number of the sulfide of 10 to 500 nm particle size is also less than 1.05 / 탆 ^2, The density was low.

In A12, Si, Mn, and Al satisfied the control range, but did not satisfy Equation 1. As a result, iron loss and magnetic flux density were inferior.

In A13, Si, Mn and Al satisfied the control range and the formula 1, respectively. However, the slab heating did not satisfy the requirement of the austenite single phase and the formula 2 was unsatisfactory. In the final product plate, the sulfide of 10 to 500 nm And the number of teeth was less than 1.05 / 탆 ² , so that iron loss and magnetic flux density were inferior.

It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims and their equivalents. It will be understood that the invention may be practiced. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (13)

0.001 to 0.005% of Al, 0.1 to less than 0.1% of Al (in terms of% by weight), C: 0.005% or less (excluding 0%), Si: 0.5 to 4%, Mn: 0.4 to 2.0% (Excluding 0%), N: 0.005% or less (excluding 0%), Ti: 0.005% or less (excluding 0%) and Sn: 0.002 to 0.2%, the balance being Fe and unavoidable impurities Wherein the number of sulfides having a particle diameter of 10 to 500 nm is 0.37 to 1.05 / mu m &lt; ² &gt;.
[Formula 1]
0.1? [Mn] / ([Si] + 10 x [Al])? 0.6
(Where, [Mn], [Si] and [Al] in the formula 1 represent the contents of Mn, Si and Al, respectively) The method according to claim 1,
A non-oriented electrical steel sheet having an average grain size of 30 to 100 탆. The method according to claim 1,
Further comprising 0.05% by weight or less (excluding 0% by weight) of Cu, Ni and Cr, respectively. The method according to claim 1,
Zr, Mo, and V in an amount of 0.01 wt% or less (excluding 0 wt%), respectively. The method according to claim 1,
_{Wherein the} iron loss (W _15/50 ) is 3.5 W / kg or less and the magnetic flux density (B ₅₀ ) is 1.75 T or more. 0.001 to 0.005% of Al, 0.1 to less than 0.1% of Al (in terms of% by weight), C: 0.005% or less (excluding 0%), Si: 0.5 to 4%, Mn: 0.4 to 2.0% (Excluding 0%), N: 0.005% or less (excluding 0%), Ti: 0.005% or less (excluding 0%) and Sn: 0.002 to 0.2%, the balance being Fe and unavoidable impurities Heating the slab satisfying the following formula (1) and hot-rolling the slab to produce a hot-rolled steel sheet;
Winding the hot-rolled sheet;
Cold rolling the rolled hot rolled sheet directly to produce a cold rolled sheet; And
And recrystallization annealing the cold rolled sheet, wherein the slab heating temperature (SRT) satisfies the following formula (2), the slab heating is performed in austenite single phase,
Wherein the produced non-oriented electrical steel sheet has a number of sulfides having a particle diameter of 10 to 500 nm of 0.37 to 1.05 / mu m &lt; ² &gt;.
[Formula 1]
0.1? [Mn] / ([Si] + 10 x [Al])? 0.6
[Formula 2]
[SRT]? [T _MnS ] -30
(SRT) is the slab heating temperature (占 폚), and [T _MnS ] represents the content of _MnS in the formula (1) and the formula (2) It shows the thermodynamic equilibrium precipitation temperature (℃).) The method according to claim 6,
Wherein the finish rolling in the hot rolling is finished in a ferrite phase. The method according to claim 6,
Wherein the hot rolled steel sheet is rolled at a temperature of 600 to 700 占 폚 in the step of winding the hot rolled steel sheet. The method according to claim 6,
In the recrystallization annealing step, a cracking temperature is 900 to 1100 占 폚. The method according to claim 6,
Wherein the slab further comprises 0.05 wt% or less (excluding 0 wt%) of Cu, Ni and Cr, respectively. The method according to claim 6,
Wherein the slab further comprises Zr, Mo and V in an amount of 0.01 wt% or less (excluding 0 wt%), respectively. delete The method according to claim 6,
Wherein the produced non-oriented electrical steel sheet has an average grain size of 30 to 100 占 퐉.