KR101353461B1 - Non-oriented electrical steel sheets and method for manufacturing the same - Google Patents

Abstract

Disclosed are a non-oriented electrical steel sheet and a method of manufacturing the same. The non-oriented electrical steel sheet according to the present invention is a weight percent (%), C: 0.005% or less, Si: 1.0 to 3.5%, Al: 0.1 to 0.3%, Mn: 0.01 to 0.07%, P: 0.02 to 0.2%, N: 0.005% or less, S: 0.001% to 0.005%, Ti: 0.005% or less, at least one of Sn and Sb is 0.01% to 0.2%, the balance includes impurities added to Fe and other unavoidably, Mn, Al, P and S are the following formulas, 0.8≤ {[Mn] / (100x [S]) + [Al]} / [P] ≤40, (where [Mn], [Al], [P], [S] Denotes the weight percentage (%) of Mn, Al, P, and S, respectively).

Description

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

The present invention relates to a non-oriented electrical steel sheet, and more particularly to a non-oriented electrical steel sheet to improve the magnetism by optimizing the content of Mn, S, Al, P.

Non-oriented electrical steel is used as a material for iron cores in rotating equipment such as motors and generators, and in stationary equipment such as small transformers, and plays an important role in determining the energy efficiency of electrical equipment.

The characteristics of the steel sheet include iron loss and magnetic flux density. The iron loss is small and the magnetic flux density is high. The higher the iron loss, the higher the iron loss when inducing a magnetic field. The higher the magnetic flux density, the greater the magnetic field can be induced with the same energy.

Therefore, in order to cope with the reduction of energy and the increasing demand for eco-friendly products, it is necessary to develop a non-oriented electrical steel sheet manufacturing technology with low iron loss and high magnetic flux density.

Among the magnetic properties of the non-oriented electrical steel sheet, typical methods for improving iron loss include a method of thinning the thickness and a method of adding an element having a high resistivity such as Si or Al.

However, in the case of the thickness is determined according to the characteristics of the product used, the thinner the thickness has the problem of lower productivity and increased cost.

The addition of Si, Al, and Mn, which are alloy elements with high resistivity, which is a method of reducing iron loss by increasing the electrical resistivity of general materials, also reduces the iron loss when the alloying elements are added, but also decreases the magnetic flux density due to the decrease of the saturation magnetic flux density. There is a contradiction that it cannot be avoided.

If the amount of Si added is more than 4%, the workability is lowered, which makes cold rolling difficult and lowers the productivity. When Al, Mn, etc. are added too much, the rolling property is lowered and hardness is increased and workability is lowered.

On the other hand, impurity elements C, S, N, Ti, etc., which are inevitably added in steel, combine with Mn, Cu, Ti, etc. to form fine inclusions of about 0.05 μm, thereby inhibiting grain growth and preventing magnetic domains from moving. Deteriorates enemy properties.

These impurities are extremely difficult to manage in the normal manufacturing process, and also the inclusion itself is difficult to control because the inclusions are re-dissolved and precipitated according to each manufacturing process.

Therefore, in order to reduce the iron loss and improve the magnetic flux density, the addition of a trace alloy element increases the {100} texture, which is advantageous to magnetic properties, and reduces the {111} texture, which is harmful to the magnetic structure, or minimizes the amount of impurities. Techniques for producing clean steel are used.

However, since all of these technologies cause an increase in manufacturing cost and the difficulty of mass production, there is a need for a technology having excellent magnetic improvement effect without significantly increasing the manufacturing cost.

The present invention has been made to solve the above problems, by optimally managing the components of Mn, S, Al, P of the alloy elements of the steel while reducing the addition amount of Mn and Al while suppressing the formation of fine inclusions and coarse It is an object of the present invention to provide a non-oriented electrical steel sheet and a method of manufacturing the same by improving the grain density and the mobility of magnetic walls by increasing the distribution density of inclusions.

In order to achieve the above object, the non-oriented electrical steel sheet according to an embodiment of the present invention is a weight percent (%), C: 0.005% or less, Si: 1.0 to 3.5%, Al: 0.1 to 0.3%, Mn: 0.01 to 1% 0.07%, P: 0.02 ~ 0.2%, N: 0.005% or less, S: 0.001 ~ 0.005%, Ti: 0.005% or less, at least one of Sn and Sb is 0.01 ~ 0.2%, the balance is Fe and other unavoidably added Contains impurities,

Mn, Al, P, S are the following formula,

0.8≤ {[Mn] / (100x [S]) + [Al]} / [P] ≤40,

(Where [Mn], [Al], [P], and [S] mean weight percent (%) of Mn, Al, P, S, respectively)).

The inevitably added impurities include Cu, Ni, Cr, Zr, Mo, and V, and the content of Cu, Ni, and Cr is added in 0.05 weight percent or less, respectively, and the Zr, Mo, and V of The content may each be added up to 0.01 weight percent (%).

The electrical steel sheet is a ratio of the number of MnS, CuS and (Mn, Cu) S composite sulfides (N S _{≧ 0.1} μm or more) of 0.1 μm or more with _respect to the total number of inclusions (N _Tot ) having a size of 0.01 to 1 μm or less (N S _{≧ 0.1 μm)} / N _Tot ) may be greater than or equal to 0.5.

The average size of the total inclusions having a size of 0.01 to 1 μm and including sulfides in the electrical steel sheet may be 0.11 μm or more.

The grain size in the microstructure of the electrical steel sheet may be 50 ~ 180㎛.

Method for producing a non-oriented electrical steel sheet according to another preferred embodiment of the present invention by weight percent (%), C: 0.005% or less, Si: 1.0 ~ 3.5%, Al: 0.1 ~ 0.3%, Mn: 0.01 ~ 0.07% , P: 0.02 ~ 0.2%, N: 0.005% or less, S: 0.001 ~ 0.005%, Ti: 0.005% or less, 0.01-0.2% of at least one of Sn and Sb, the balance of Fe and other unavoidable impurities Include,

Mn, Al, P, S are the following formula,

0.8≤ {[Mn] / (100x [S]) + [Al]} / [P] ≤40,

Providing a slab that satisfies (wherein [Mn], [Al], [P], [S] represents the weight percent (%) of Mn, Al, P, S), respectively), the slab being 1,200 Manufacturing a hot rolled steel sheet by heating to less than or equal to ℃ ℃, pickling the hot rolled steel sheet, and then rolling to 0.10 to 0.70 mm to manufacture a cold rolled steel sheet, and finishing annealing the cold rolled steel sheet at 850 to 1,100 ° C. It includes.

The inevitably added impurities include Cu, Ni, Cr, Zr, Mo, and V, and the content of Cu, Ni, and Cr is added in 0.05 weight percent or less, respectively, and the Zr, Mo, and V of The content may each be added up to 0.01 weight percent (%).

The method for manufacturing the non-oriented electrical steel sheet may further include annealing the hot rolled sheet at a temperature range of 850 to 1,150 ° C.

The ratio of the number of MnS, CuS, and (Mn, Cu) S composite sulfides (N _S≥0.1 μm) of 0.1 μm or more to the total number of inclusions (N _Tot ) having a size of 0.01 to 1 μm or less in the finished electrical annealing ( N _{S ≧ 0.1 μm} / N _Tot ) may be 0.5 or more.

In the electrical steel sheet in which the finish annealing is completed, the average size of the entire inclusion including a sulfide having a size of 0.01 to 1 μm may be 0.11 μm or more.

The size of the crystal grains in the microstructure of the electrical steel sheet after the finish annealing may be 50 ~ 180㎛.

According to the present invention, by optimally managing the components of Mn, S, Al, P in the alloy elements of the steel, while reducing the amount of Mn and Al added, while suppressing the formation of fine inclusions and increasing the distribution density of coarse inclusions, It is possible to provide a non-oriented electrical steel sheet having excellent magnetic properties and its manufacturing method by improving the mobility of the magnetic wall.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, a non-oriented electrical steel sheet according to a preferred embodiment of the present invention will be described.

Non-oriented electrical steel sheet according to a preferred embodiment of the present invention is a weight percent (%), C: 0.005% or less, Si: 1.0 ~ 3.5%, Al: 0.1 ~ 0.3%, Mn: 0.01 ~ 0.07%, P: 0.02 -0.2%, N: 0.005% or less, S: 0.001-0.005%, Ti: 0.005% or less, 0.01-0.2% of at least one of Sn and Sb, the balance includes Fe and other unavoidable impurities,

Mn, Al, P, S are the following formula,

<Composition>

0.8≤ {[Mn] / (100x [S]) + [Al]} / [P] ≤40,

(Where [Mn], [Al], [P], and [S] mean weight percent (%) of Mn, Al, P, S, respectively)).

In general, Mn is added at least 0.1% in the production of non-oriented electrical steel sheet together with Al and Si to reduce the iron loss by increasing the resistivity of the steel.

However, Mn combines with S to form a precipitate of MnS. In addition, the impurity element S combines with Cu to form CuS or Cu ₂ S. That is, S combines with Mn and Cu to form a sulfide, and the sulfide is formed of MnS or CuS alone or a composite inclusion of (Mn, Cu) S.

Inclusions of non-oriented electrical steel sheets are generally about 0.05 μm in size, which inhibits grain growth and disturbs the movement of the magnetic domain walls, which greatly affects magnetism. Therefore, the frequency of formation of coarse inclusions is increased to minimize magnetic deterioration. There is a need.

Al added as a resistivity element also forms a fine nitride and causes magnetism to become weak. In the prior art, it is known that inclusions become finer when the amount of Mn and Al is decreased.

According to the present invention, Mn, Al, P, S is 0.8≤ {[Mn] / (100 * [S]) + [Al]} / [P] ≤40 (wherein [Mn], [S], When [Al] and [P] control the component content to satisfy the weight percent (%) of Mn, S, Al, and P, respectively, the expectation is that the inclusions will be finer if the amount of Mn and Al is reduced. Otherwise, the average size of inclusions of 0.01 μm or more and 1 μm or less becomes coarse.

In addition, more than 0.01μm total number of inclusions (N _Tot) than 0.1μm or more MnS, Cus alone or combined sulphide of 1μm or less ((Mn, Cu) S and so on), the number (N _S≥0.1μm) the ratio of (N _{S≥0.1 μm} / N _Tot ) becomes coarse above 0.5.

In other words, by adjusting the distribution density of the inclusions in the steel sheet, it is possible to obtain a non-oriented electrical steel sheet having low iron loss and high magnetic flux density even though an alloy element is added in a minimum amount.

More specifically, in the present invention, the reason for limiting the amount of Mn, Al, P, and S added as in the above formula is that the ratio of Mn / S is important for determining the distribution and size of inclusions, especially sulfides, and Al. Also, the addition amount is important as an element to form fine inclusions, especially nitrides, and since P is also an element segregating at grain boundaries, an appropriate ratio of addition amount of Mn, Al, and S to affect inclusion formation is appropriate. This is because it can have a very important effect on eliminating grain growth inhibition and enhancing magnetism through coarsening.

That is, when the value of the composition formula is less than 0.8 or greater than 40, the inclusions are not coarsened and the distribution density of the fine inclusions is increased, thereby inhibiting magnetic growth, such as inhibiting grain growth and preventing magnetic domain movement.

In addition, the ratio of the number of MnS, CuS and (Mn, Cu) S composite sulfides (N _S≥0.1 μm or more) of 0.1 μm or more to the total number of inclusions (N _Tot ) having a size of 0.01 to 1 μm or less (N _{S≥0.1 μm} / N _Tot ) is greater than or _equal to 0.5.

In addition, it is preferable that the average size of the total inclusions having a size of 0.01 to 1 μm and containing sulfides in the electrical steel sheet is 0.11 μm or more.

In addition, the size of ferrite grains in the microstructure of the electrical steel sheet is 50 ~ 180㎛. Increasing the size of the ferrite grains is advantageous because the hysteresis loss during iron loss is reduced, but the vortex loss during iron loss increases, so the size of the crystal grains desirable to minimize such iron loss is limited as described above.

The reason for limiting the content of the components of the non-oriented electrical steel sheet according to the present invention is as follows.

Si: 1.0 to 3.5 wt%

The Si is a main element added because it increases the specific resistance of the steel to lower the vortex loss in the iron loss, it is difficult to obtain the low iron loss characteristics less than 1.0%, and when added in excess of 3.5% breakage of the sheet during cold rolling It is preferable to limit to 1.0 to 3.5% by weight.

Mn: 0.01 to 0.07% by weight

Since Mn has an effect of lowering iron loss by increasing specific resistance of steel together with Si and Al, in the conventional non-oriented electrical steel sheet, Mn is added for the purpose of improving iron loss by adding at least 0.1%.

However, as the amount of Mn added increases, the saturation magnetic flux density decreases, so the magnetic flux density decreases. In addition, it forms a fine MnS inclusion in combination with S to suppress grain growth. .

Therefore, in order to improve magnetic flux density and prevent iron loss due to inclusions, the amount of Mn added is limited to 0.01 to 0.07%. Preferably, when the content of Mn is reduced, fine precipitates are reduced to improve magnetic properties, so that the magnetic content is increased to 0.01 to 0.05%.

Al: 0.1 to 0.3 wt%

Al is an element that is inevitably added for deoxidation of steel in the steelmaking process, and is mainly added to reduce iron loss, but also serves to reduce saturation magnetic flux density.

In addition, when the amount of Al added is excessively less than 0.1%, fine AlN is formed to suppress grain growth and the magnetism is lowered. When the amount of Al added is more than 0.3%, the magnetic flux density is reduced, so the amount of addition is 0.1 to 0.3. It is desirable to limit to%.

P: 0.02 to 0.2 wt%

The P suppresses formation of {111} aggregates harmful to magnetism by increasing specific resistance, lowering iron loss and segregation at grain boundaries, and forming {100}, which is an advantageous texture, but when added in an amount of 0.2% or more, 0.02 to 0.2 weight It is preferably added in%.

C: 0.005 wt% or less

When C is added a lot, the austenite region is expanded, the phase transformation period is increased, and ferrite grain growth is suppressed by annealing, thereby increasing iron loss. It is limited to less than 0.005% because iron loss is increased by self-aging when processed from product to electric product.

S: 0.001 to 0.005% by weight or less

S is an element which forms sulfides such as MnS, CuS, and (Cu, Mn) S, which are detrimental to magnetic properties. Therefore, it is preferable to add S as low as possible. However, if it is added below 0.001%, it is rather disadvantageous to form tissue, and the content of magnetism is lowered. Therefore, if it is added more than 0.005%, the magnetic content is deteriorated due to the increase of fine sulfide. Limit to content.

N: 0.005 wt% or less

Since N is an element harmful to magnetism, such as forming a nitride by strongly bonding with Al, Ti, etc. to suppress grain growth, it is preferable to contain N less than 0.005% by weight or less.

Ti: 0.005 wt% or less

Ti inhibits grain growth by forming fine carbides and nitrides, and as the amount of Ti increases, the carbides and nitrides increase inferior texture and deteriorate magnetic properties. Therefore, the Ti content is limited to 0.005% or less.

Sn or Sb: 0.01 to 0.2 wt%

Sn and Sb are added to improve magnetic properties by inhibiting diffusion of nitrogen through grain boundaries as segregates at grain boundaries, inhibiting {111} textures that are harmful to magnetism, and increasing advantageous {100} textures.

When Sn or Sb alone or a sum of 0.2% or more is added, the grain growth is suppressed to decrease magnetism and the rolling property becomes worse. Therefore, Sn or Sb alone or a sum thereof is added at 0.01 to 0.2%.

The inevitably added impurities include Cu, Ni, Cr, Zr, Mo, and V, and the content of Cu, Ni, and Cr is added in 0.05 weight percent or less, respectively, and the Zr, Mo, and V of The content is added up to 0.01 weight percent (%) each.

The impurities may be inevitably added in the steel manufacturing process in the steelmaking process, and, in the case of Cu, Ni, and Cr, react with the impurity elements to form fine sulfides, carbides, and nitrides, which have a detrimental effect on the magnetic properties, respectively. It is limited to 0.05% by weight or less.

In addition, Zr, Mo, and V is also a strong carbonitride-forming element, so it is preferable not to be added as much as possible.

In addition to the above compositions, the remainder contains Fe and other unavoidable impurities that may be added in the steelmaking process.

Hereinafter, a method of manufacturing a non-oriented electrical steel sheet according to another embodiment of the present invention.

In weight percent (%), C: 0.005% or less, Si: 1.0 to 3.5%, Al: 0.1 to 0.3%, Mn: 0.01 to 0.07%, P: 0.02 to 0.2%, N: 0.005% or less, S: 0.001 0.005%, Ti: 0.005% or less, at least one of Sn and Sb is 0.01-0.2%, the balance includes Fe and other unavoidable impurities,

Mn, Al, P, S are the following formula,

0.8≤ {[Mn] / (100x [S]) + [Al]} / [P] ≤40,

(Wherein [Mn], [Al], [P], [S] means the weight percent (%) of Mn, Al, P, S, respectively)) To produce a hot-rolled steel sheet.

When the heating temperature is 1,200 ° C. or more, precipitates such as AlN, MnS, etc. present in the slab are re-used and finely precipitated during hot rolling to inhibit grain growth and lower magnetism, so the reheating temperature is limited to 1200 ° C. or less.

The finish rolling in filamentary rolling during hot rolling is finished in the ferrite phase and the final rolling rate is 20% or less for the correction of plate shape.

The hot-heated steel sheet manufactured as described above is wound up at 700 ° C. or lower, and cooled in air. The wound cooled hot rolled steel sheet is subjected to hot rolled sheet annealing, pickling, cold rolling, and finally cold rolled sheet annealing if necessary.

Hot-rolled sheet annealing is to anneal the hot-rolled sheet when necessary to improve the magnetic properties, hot-rolled sheet annealing temperature is to be 850 ~ 1,150 ℃. When the hot-rolled sheet annealing temperature is lower than 850 ° C, grain growth is insufficient. When the hot-rolled sheet annealing temperature is lower than 850 ° C, the grains grow excessively and the surface defects of the plate become excessive, so the annealing temperature is set to 850-1150 ° C.

Hot rolled steel sheets pickled in the usual manner or annealed hot rolled steel sheets are cold rolled.

The cold rolling is finally rolled to a thickness of 0.10 mm to 0.70 mm. If necessary, the first cold rolling and the second annealing after the intermediate annealing can be carried out, and the final rolling rate is in the range of 50 ~ 95%.

The final cold rolled steel sheet is cold rolled (annealed). In the annealing process of the cold rolled steel sheet, the cold rolled sheet annealing (finishing annealing) temperature during the annealing is 850-1100 ° C.

Cold rolling plate annealing temperature (finish annealing) is less than 850 ℃, grain growth is insufficient, and {111} texture, which is harmful to magnetism, increases, and grains grow excessively above 1,100 ℃, which adversely affects magnetism. Since the cold rolled steel sheet may be finished, the annealing temperature is 850 to 1100 ° C.

After that, the annealing plate may be insulated coating.

Hereinafter, the method for producing a non-oriented electrical steel sheet according to the present invention through the embodiment will be described in detail. The following examples are illustrative of the present invention only and are not intended to limit the scope of the present invention.

&Lt; Example 1 >

The steel ingot was prepared as shown in Table 1 through vacuum melting to change the amount of Mn, Al, P, S to see the effect. Each ingot was heated at 1180 ° C., hot rolled to a thickness of 2.1 mm, and wound up. The hot rolled steel sheet wound and cooled in air was annealed at 1080 ° C. for 3 minutes, pickled and cold rolled to a thickness of 0.35 mm, and the cold rolled sheet annealed at 1050 ° C. for 90 seconds. For each specimen, the number of inclusions of 0.01 μm or more and 1 μm or less, the number of sulfides having a size of 0.1 μm or more, iron loss and magnetic flux density were measured. The results are shown in Table 2 below.

Steel grade C Si Mn P S Al N Ti Sn Sb Remarks A1 0.0022 1.5 0.04 0.15 0.0044 0.2 0.0025 0.0014 0.025 0 Honor A2 0.0027 2.4 0.05 0.12 0.0037 0.22 0.0021 0.0016 0.035 0.023 Honor A3 0.0013 2.6 0.01 0.06 0.0031 0.19 0.0014 0.001 0.013 0.026 Honor A4 0.0022 2.0 0.004 0.23 0.0048 0.005 0.0026 0.001 0.044 0 Comparative Example A5 0.0025 2.6 0.03 0.07 0.0034 0.42 0.0021 0.0009 0.013 0.026 Comparative Example A6 0.0022 2.8 0.04 0.02 0.0028 0.16 0.0017 0.002 0 0.015 Honor A7 0.0019 2.9 0.07 0.03 0.0012 0.29 0.0019 0.0009 0.026 0.022 Honor A8 0.0024 2.8 0.08 0.007 0.0021 0.13 0.0019 0.0016 0.029 0.05 Comparative Example A9 0.0029 2.8 0.06 0.02 0.0011 0.29 0.0016 0.0017 0 0.028 Comparative Example A10 0.0033 3.2 0.11 0.02 0.0029 0.5 0.0015 0.0025 0 0.048 Comparative Example A11 0.0029 3.1 0.06 0.07 0.0038 0.3 0.0026 0.0016 0.019 0 Honor A12 0.0025 3.3 0.04 0.04 0.0025 0.27 0.0016 0.0012 0 0.025 Honor A13 0.0035 3.5 0.03 0.03 0.0013 0.15 0.0039 0.0015 0.025 0.016 Honor A14 0.0025 3.3 0.12 0.06 0.0064 0.29 0.0015 0.0019 0 0.021 Comparative Example A15 0.0024 3.5 0.1 0.05 0.0007 0.18 0.0041 0.0016 0 0.036 Comparative Example

Steel grade {[Mn] / (100x [S]) + [Al]} / [P] 0.01 ~ 1μm
Inclusion
Average size (μm) N _{s≥0.1 μm}
/ N _Tot ¹⁾ Iron loss
W15 / 50 ²⁾ Magnetic flux density
B50 ₃₎ Remarks A1 1.9 0.155 0.57 2.30 1.77 Honor A2 3.0 0.137 0.62 2.23 1.76 Honor A3 3.7 0.133 0.58 1.92 1.75 Honor A4 0.1 0.088 0.39 2.91 1.69 Comparative Example A5 7.3 0.095 0.43 2.77 1.70 Comparative Example A6 15.1 0.156 0.68 1.87 1.76 Honor A7 29.1 0.128 0.61 2.02 1.74 Honor A8 73.0 0.098 0.45 2.79 1.67 Comparative Example A9 41.8 0.103 0.48 2.67 1.67 Comparative Example A10 44.0 0.091 0.41 2.53 1.65 Comparative Example A11 6.5 0.135 0.66 2.04 1.73 Honor A12 10.8 0.151 0.7 1.97 1.73 Honor A13 12.7 0.163 0.67 1.85 1.71 Honor A14 8.0 0.093 0.33 2.55 1.65 Comparative Example A15 32.2 0.102 0.41 2.51 1.64 Comparative Example

1) (N _S≥0.1μm / N _Tot ) means the ratio of the number of MnS, CuS or complex sulfides having a size of 0.1μm or more among the total inclusions of 0.01 to 1μm or less.

2) _Iron loss (W _15/50 ) means the average loss (W / kg) in the rolling direction and the vertical direction when the magnetic flux density of 1.5 Tesla is induced at 50 Hz.

3) Magnetic flux density (B ₅₀ ) means the magnitude of magnetic flux density (Tesla) induced when a magnetic field of 5000 A / m is added.

In the present invention, as a method for analyzing the size, type, and distribution of inclusions, a carbon replica extracted from the specimen was observed with a transmission electron microscope (TEM) and analyzed by EDS.

TEM observation was a randomly selected area with no bias and was set at a magnification that clearly contained 0.01 μm or larger inclusions, and then measured the size and distribution of all inclusions taken by at least 100 images, and also measured carbonitrides through EDS spectrum Types of inclusions, emulsions, etc. were analyzed.

In analyzing the size and distribution of inclusions in the present invention, in the case of inclusions of 0.01 μm or less, it is difficult to observe and measure, and the effect on magnetism is small, and also oxides such as SiO ₂ and Al ₂ O _{3 of} 1 μm or more are observed. However, the influence on the magnetism is small and was not included in the analysis target of the present invention.

As shown in Table 2, [Mn], [Al], [P], [S] and 0.8≤ {[Mn] / (100x [S]) + [Al]} / [P] ≤ of the present invention. For steel grades A1, A2, A3, A6, A7, A11, A12, and A13 that satisfy the composition formula of 40, the average size of inclusions of 0.01 μm or more and 1 μm or more was also 0.11 μm or more and 0.1 μm or more of the number of inclusions of 0.01 μm or more and 1 μm or less. The number ratio (N _{S ≥0.1μm} / N _Tot ) of MnS, CuS or composite sulfides with size also was over 0.5, resulting in low iron loss and high magnetic flux density.

On the other hand, A4, A8, A10, Mn, P, Al, etc., did not satisfy the composition formula beyond the control range, and the average size of inclusions of 0.01 μm or more and 1 μm or less was fine to 0.11 μm or less and 0.01 μm or more and 1 μm or less of the inclusions. N _{S ≥} 0.1 μm / N _{Tot, which} is the number ratio of MnS, CuS or complex sulfides having a size of 0.1 μm or more, was also less than 0.5, resulting in inferior iron loss and magnetic flux density.

In A5, A14 and A15, Al, Mn, and P were out of control range, respectively, and as a result, the average size of inclusions of 0.01 μm or more and 1 μm or less was 0.11 μm or less, and 0.1 μm or more of the number of inclusions of 0.01 μm or more and 1 μm or less. The number ratio of MnS, CuS or composite sulfides with (N _{S ≥ 0.1 μm} / N _Tot ) was also less than 0.5, indicating poor iron loss and magnetic flux density.

In the case of A9, Mn, P, S, and Al were satisfied with the component management range, but the composition formula was not satisfied.As a result, the average size of inclusions of 0.01 μm or more and 1 μm or less was 0.11 μm or less and 0.01 μm or more and 1 μm or less. The number ratio of MnS, CuS or complex sulfide (N _{S ≥} 0.1 μm / N _Tot ) having a size of 0.1 μm or more among the inclusions of was also less than 0.5, _resulting in inferior iron loss and magnetic flux density.

<Example 2>

A steel ingot prepared as shown in Table 3 was prepared through vacuum dissolution. At this time, the effects of hot-rolled sheet annealing and cold-rolled sheet annealing temperature on the inclusion size, distribution and magnetic properties. Each ingot was heated at 1,180 ° C, hot rolled to a thickness of 2.5 mm, and wound up. The hot rolled steel sheet wound and cooled in air was annealed at 800-1,200 ° C. for 2 minutes, pickled, and cold rolled to a thickness of 0.35 mm, and the cold rolled sheet annealed at 800-1,200 ° C. for 50 seconds. For each specimen, the number of inclusions of 0.01 μm or more and 1 μm or less, the number of sulfides having a size of 0.1 μm or more, iron loss and magnetic flux density were measured, and the results are shown in Table 4 below.

Steel grade C Si Mn P S Al N Ti Sn Sb Remarks B1 0.0012 1.3 0.03 0.14 0.0012 0.1 0.0029 0.0009 0.046 0.021 Honor B2 0.0022 2.1 0.06 0.05 0.0019 0.18 0.0016 0.0025 0.021 0.025 Honor B3 0.0035 2.5 0.05 0.11 0.0038 0.15 0.0035 0.0015 0.039 0 Honor B4 0.0027 2.8 0.05 0.07 0.0021 0.21 0.0019 0.0016 0 0.041 Honor B5 0.0021 1.7 0.07 0.11 0.0012 0.12 0.0022 0.0008 0.011 0.031 Comparative Example B6 0.0016 2.3 0.05 0.02 0.0019 0.29 0.0019 0.0023 0.035 0 Comparative Example B7 0.0025 2.4 0.07 0.08 0.0022 0.26 0.0022 0.0012 0 0.025 Comparative Example B8 0.0031 2.8 0.03 0.05 0.0017 0.22 0.0016 0.0019 0.029 0.011 Honor B9 0.0019 3.0 0.05 0.08 0.0035 0.24 0.0023 0.0021 0.029 0.022 Honor B10 0.0029 3.5 0.06 0.06 0.0037 0.29 0.0029 0.0015 0.045 0 Honor B11 0.0023 3.5 0.04 0.03 0.003 0.13 0.0021 0.0011 0 0.036 Honor B12 0.0033 2.8 0.07 0.05 0.0023 0.18 0.0025 0.0019 0.030 0 Comparative Example B13 0.0027 3.1 0.06 0.07 0.0016 0.3 0.0013 0.0016 0.032 0.03 Comparative Example B14 0.0016 3.3 0.05 0.04 0.0027 0.19 0.0026 0.0017 0 0.024 Comparative Example

Steel grade {Mn / (100x [S]) + [Al]} / [P] Hot-rolled plate
Annealing temperature
(℃) Cold rolled plate
Annealing temperature
(℃) 0.01 ~ 1μm
Inclusion
Average size (μm) N _{s≥0.1 μm}
/ N _tot Iron loss
W15 / 50 Magnetic flux
density
B50 Remarks B1 2.5 1080 970 0.136 0.62 2.39 1.77 Honor B2 9.9 1020 1010 0.145 0.55 2.25 1.75 Honor B3 2.6 1040 1050 0.125 0.51 2.21 1.74 Honor B4 6.4 990 1040 0.141 0.59 2.16 1.74 Honor B5 6.4 830 1040 0.096 0.42 2.92 1.71 Comparative Example B6 27.7 1020 1120 0.100 0.46 2.85 1.68 Comparative Example B7 7.2 1170 990 0.107 0.31 2.65 1.67 Comparative Example B8 7.9 1040 1050 0.166 0.53 1.89 1.76 Honor B9 4.8 1080 1030 0.148 0.55 1.96 1.76 Honor B10 7.5 1100 990 0.114 0.58 2.03 1.72 Honor B11 8.8 1050 1040 0.138 0.61 1.94 1.71 Honor B12 9.7 800 1050 0.098 0.35 2.61 1.66 Comparative Example B13 9.6 1180 1130 0.093 0.49 2.62 1.64 Comparative Example B14 9.4 1020 820 0.101 0.37 2.54 1.64 Comparative Example

As shown in Table 3, [Mn], [Al], [P], [S] and 0.8 ≦ {[Mn] / (100 × [S]) + [Al]} / [P] ≦ of the present invention. Steel grades B1, B2, B3, B4, B8, B9, B10, and B11 that satisfy the composition formula of 40 and satisfy the cold rolled sheet annealing temperature and the cold rolled sheet annealing temperature, had an average size of inclusions of 0.01 μm or more and 1 μm or more, and 0.011 μm or more. MnS, CuS or _Ns (N _S≥0.1μm / N _Tot ), which has a size ratio of 0.1μm or more among the inclusions of μm or more and 1μm or less, also showed more than 0.5, resulting in low iron loss and high magnetic flux density. .

On the other hand, B5, B7 and B12 are the formulas of [Mn], [Al], [P], [S] and 0.8≤ {[Mn] / (100x [S]) + [Al]} / [P] ≤40 Although the hot-rolled sheet annealing temperature is beyond the scope of the present invention, the fraction of fine inclusions increases, so that the average size of inclusions of 1 μm or less is also 0.11 μm or less, and MnS having a size of 0.1 μm or more of the number of inclusions of 0.01 μm or more and 1 μm or less. The number ratio of CuS or complex sulfides (N _{S ≥ 0.1 μm} / N _Tot ) was also less than 0.5, resulting in inferior iron loss and magnetic flux density.

In addition, B6 and B14 satisfy the composition formula of [Mn], [Al], [P], [S] and 0.8≤ {[Mn] / (100x [S]) + [Al]} / [P] ≤40. The cold rolled sheet annealing temperature is outside the scope of the present invention, the average size of inclusions of 1 μm or less is also 0.11 μm, and the number ratio of MnS, CuS or complex sulfide having a size of 0.1 μm or more of the number of inclusions of 0.01 μm or more and 1 μm or less (N _{S ≥0.1μm} / N _Tot ) was also less than 0.5 and the grains were too coarse or fine, resulting in inferior iron loss and magnetic flux density.

B13 satisfied the composition formula of [Mn], [Al], [P], [S] and 0.8≤ {[Mn] / (100x [S]) + [Al]} / [P] ≤40, but the hot-rolled sheet was annealed. Both the temperature and the cold-rolled sheet annealing temperature are outside the scope of the present invention and the average size of inclusions of 1 μm or less is also 0.11 μm, and the number ratio of MnS, CuS or complex sulfide having a size of 0.1 μm or more of the number of inclusions of 0.01 μm or more and 1 μm or less. (N _{S ≧ 0.1 μm} / N _Tot ) was also less than 0.5, which resulted in inferior magnetism.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

Claims (11)

In weight percent (%), C: 0.005% or less (0%), Si: 1.0 to 3.5%, Al: 0.1 to 0.3%, Mn: 0.01 to 0.07%, P: 0.02 to 0.2%, N : 0.005% or less (does not contain 0%), S: 0.001% to 0.005%, Ti: 0.005% or less (does not contain 0%), at least one of Sn and Sb is 0.01 to 0.2%, the balance is Fe and Other impurities inevitably added,
Mn, Al, P, S are the following formula,
0.8≤ {[Mn] / (100x [S]) + [Al]} / [P] ≤40,
(Where [Mn], [Al], [P], and [S] mean weight percent (%) of Mn, Al, P, S, respectively)),
Total number of inclusions having a size less than 0.01 ~ 1μm in the microstructure of the electrical steel sheet or more than 0.1μm (N _Tot) MnS, CuS and the ratio of (Mn, Cu) S sulfide complex number (N _S≥0.1㎛) (N _{S≥ 0.1 µm} / N _Tot ) is a non-oriented electrical steel sheet, characterized in that more than 0.5. The method of claim 1,
The inevitably added impurities include Cu, Ni, Cr, Zr, Mo, and V, and the content of Cu, Ni, and Cr is added in 0.05 weight percent or less, respectively, and the Zr, Mo, and V of The non-oriented electrical steel sheet is added in an amount of less than 0.01% by weight (%), respectively. delete 3. The method according to claim 1 or 2,
Non-oriented electrical steel sheet having a size of 0.01 ~ 1μm in the electrical steel sheet and the average size of the total inclusions containing sulfide is 0.11μm or more. 5. The method of claim 4,
Non-oriented electrical steel sheet, characterized in that the size of the crystal grains in the microstructure of the electrical steel sheet 50 ~ 180㎛. In weight percent (%), C: 0.005% or less (0%), Si: 1.0 to 3.5%, Al: 0.1 to 0.3%, Mn: 0.01 to 0.07%, P: 0.02 to 0.2%, N : 0.005% or less (does not contain 0%), S: 0.001% to 0.005%, Ti: 0.005% or less (does not contain 0%), at least one of Sn and Sb is 0.01 to 0.2%, the balance is Fe and Other impurities inevitably added,
Mn, Al, P, S are the following formula,
0.8≤ {[Mn] / (100x [S]) + [Al]} / [P] ≤40,
Providing a slab that satisfies (wherein [Mn], [Al], [P], [S] represents the weight percent (%) of Mn, Al, P, S, respectively));
Manufacturing a hot rolled steel sheet by heating the slab to 1,200 ° C. or less and then rolling the slab;
Manufacturing the cold rolled steel sheet by pickling the hot rolled steel sheet and then rolling it to 0.10 to 0.70 mm; And
Comprising the step of finishing annealing the cold rolled steel sheet at 850 ~ 1,100 ℃,
The number of MnS, CuS and (Mn, Cu) S composite sulfides (N S _≧ 0.1 μm) of 0.1 μm or more relative to the total number of inclusions (N _Tot ) having a size of 0.01 to 1 μm or less in the microstructure of the finished steel sheet A method of producing a non-oriented electrical steel sheet, characterized in that the ratio (N _{S ≥ 0.1㎛} / N _Tot ) is 0.5 or more. The method according to claim 6,
The inevitably added impurities include Cu, Ni, Cr, Zr, Mo, and V, and the content of Cu, Ni, and Cr is added in 0.05 weight percent or less, respectively, and the Zr, Mo, and V of The content is a method for producing a non-oriented electrical steel sheet is added to each 0.01 weight percent (%) or less. The method according to claim 6 or 7,
The method of manufacturing a non-oriented electrical steel sheet further comprising the step of annealing the hot rolled steel sheet at a temperature range of 850 ~ 1,150 ℃. delete The method according to claim 6,
In the electrical steel sheet, the finish annealing is completed,
Method of producing a non-oriented electrical steel sheet having a size of 0.01 ~ 1μm and the average size of the total inclusions containing sulfide is 0.11μm or more. The method according to claim 6,
The size of the crystal grains in the microstructure of the electrical steel sheet is a manufacturing method of the non-oriented electrical steel sheet, characterized in that 50 ~ 180㎛.