KR101842417B1 - Electrical steels with (100) texture and method for manufacturing the same - Google Patents

Abstract

The present invention relates to an electrical steels with (100) texture and a method for manufacturing the same (100). A non-oriented electrical steels according to the present invention comprises: 2.0-3.5 wt% of Si; 0.02-0.50 wt% of Mn; equal to and less than 0.004 wt% (excluding 0 wt%) of C; equal to and less than 0.004 wt% (excluding 0 wt%) of N; equal to and less than 0.01 wt% (excluding 0 wt%) of S; and the balance Fe and other unavoidable impurities. Besides, the maximum surface strength of {100} texture is not equal to and more than 30, and <001> an angle formed by the crystal direction within {100} the texture representing the maximum face strength with the rolling direction represents any one of an angle of 0-30 degrees or 45 degrees.

Description

Technical Field [0001] The present invention relates to an electrical steel sheet composed of (100)

More particularly, the present invention relates to an electric steel sheet composed of a {100} texture and a method of manufacturing the same, and more particularly, Directional electrical steel sheet composed of {100} ordered structure improved by the present invention and a method of manufacturing the same.

The nonoriented electric steel sheet plays an important role in determining the energy efficiency of the electric equipment because the nonoriented electric steel sheet is used as an iron core material in rotating devices such as motors and generators and stationary devices such as small transformers, This is because it plays a role of converting it into mechanical energy.

The magnetic properties of the electric steel sheet include iron loss and magnetic flux density. The iron loss is energy loss, so the lower the better. On the other hand, when the magnetic flux density characteristic showing the property of easy magnetization is high, since the same magnetic flux density can be obtained even when a smaller current is applied, the heat loss caused by the copper wire wound can be reduced, and the higher the magnetic flux density characteristic, the better.

Generally, among the magnetic properties of the non-oriented electrical steel sheet, a method of adding Si, Al, Mn or the like, which is an alloy element having a high resistivity, is used for the purpose of improving the iron loss. However, addition of an alloying element reduces the iron loss, but also decreases the magnetic flux density due to the decrease of the saturation magnetic flux density. In addition, when the amount of addition of silicon (Si) and aluminum (Al) increases, cold rolling becomes difficult, resulting in decreased productivity and increased hardness, resulting in poor workability.

As a method for effectively improving the magnetic properties through improvement of the texture, there is a method using a microalloy element. By using this, it is possible to manufacture a clean steel by reducing the fraction of crystal grains parallel to the <111> axis in the direction perpendicular to the sheet, which is a harmful texture, or by reducing the amount of impurities extremely.

However, all of these technologies cause a rise in manufacturing costs and difficulties in mass production, so that technology for improving magnetic properties is required without significantly increasing the manufacturing cost.

In order to solve these problems, there have been continuous efforts in Japanese Patent Application No. 2012-112015, Japanese Patent Application Laid-Open No. 2011-179027 and Korean Patent Laid-Open No. 1998-026183, but there has been a problem such as deterioration of magnetism, increase in cost or decrease in productivity.

In addition, aluminum (Al) together with silicon (Si) and manganese (Mn) is a major element that increases electrical resistivity. It also reduces iron loss by lowering eddy loss, but forms fine inclusions by bonding with nitrogen (N) Which is a main factor for lowering the magnetic property, and also serves to suppress the growth of the ferrite phase, which is a factor for lowering the magnetic property.

However, there are few techniques to improve the magnetic flux density by controlling the addition amount of aluminum (Al) in steel. Japanese Unexamined Patent Application Publication No. 2004-292829 discloses a method for improving the magnetic properties of aluminum (Al) of 0.0005% or less and silicon (Si) of 0.7-1.5%, but refining a small amount of aluminum (Al) It has been difficult to apply it to high-grade electrical steel sheets depending on the manufacturing difficulties and the low silicon (Si) content.

In the nonoriented electric steel sheet, the iron loss is lowered when the grain size is increased in the factors affecting the magnetic properties. However, if the aggregate structure that is easy to magnetize is not developed, the aggregate structure is more important because it increases iron loss and lowers the magnetic flux density. It is preferable that the {100} planes of the crystal grains are parallel to each other, and the {111} planes or {211} planes are preferably low in the texture of the set texture. In the texture, the {110} plane is advantageous in comparison with the {100} plane parallel to the {111} plane or {112} plane as compared to the plane parallel to the plane. .

Japanese Laid-Open Patent Publication No. 2012-112015, Japanese Laid-Open Patent Application No. 2011-179027 Korea Patent Publication No. 1998-026183 Japanese Patent Application Laid-Open No. 2004-292829

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and more particularly, it is an object of the present invention to minimize the sulfur (S) An electric steel sheet and a manufacturing method thereof.

On the other hand, other unspecified purposes of the present invention will be further considered within the scope of the following detailed description and easily deduced from the effects thereof.

In order to achieve the above object, the non-oriented electrical steel sheet according to an embodiment of the present invention includes 2.0 to 3.5% of Si, 0.02 to 0.50% of Mn, 0.004% or less of C (excluding 0%), , N: not more than 0.004% (excluding 0%), S: not more than 0.001% (excluding 0%), the balance Fe and other unavoidable impurities, the maximum surface strength of the {100} The angle formed by the <001> crystal direction in the {100} texture representing the surface strength with the rolling direction is any one of 0 degree to 30 degrees or 45 degrees.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, the thickness of the electrical steel sheet may be 0.05 to 0.3 mm.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, the average grain diameter of the electrical steel sheet may be 9 to 50 times the thickness of the electrical steel sheet.

A method for producing a non-oriented electrical steel sheet according to one embodiment of the present invention comprises: a) 2.0 to 3.5% Si, 0.02 to 0.50% Mn, 0.004% or less C (excluding 0% % Or less (excluding 0%), S: not more than 0.02% (excluding 0%), the remainder Fe and other unavoidable impurities to 1200 ° C or less; b) hot rolling the reheated slab to obtain a hot rolled sheet; c) annealing the hot-rolled sheet by heating the hot-rolled sheet to 950 to 1150 캜 and then cooling it; d) cold-rolling the annealed hot-rolled sheet to a two-stage cold-rolled sheet including one-stage cold rolling or intermediate annealing not including intermediate annealing to obtain a cold-rolled sheet; And e) final annealing the cold-rolled sheet at 950 to 1250 占 폚 in a reducing gas atmosphere.

In the method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention, in the step (e), the final annealing may be performed at a temperature of 10 to 14400 DEG C / h.

In the method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention, in the step e), the final annealing may be performed at the temperature for 10 to 60 hours.

In the non-oriented electrical steel sheet manufacturing method according to an embodiment of the present invention, pre-annealing is performed between the steps d) and e) by heating the cold-rolled sheet to 1000 to 1100 ° C and cooling Step &lt; / RTI &gt;

As described above, according to the non-oriented electrical steel sheet and the method for manufacturing the same according to the present invention, the sulfur (S) component is minimized and the cold rolling process is controlled to efficiently arrange the aggregate structure favorable to magnetism, A directional electrical steel sheet can be provided.

On the other hand, even if the effects are not explicitly mentioned here, the effect described in the following specification, which is expected by the technical features of the present invention, and its potential effects are treated as described in the specification of the present invention.

1 is a view showing an orientation distribution function (ODF) obtained by observing a non-oriented electrical steel sheet according to Comparative Example 2 with an EBSD.
FIG. 2 is a view showing an orientation distribution function (ODF) obtained by observing a non-oriented electrical steel sheet according to Inventive Example 3 with an EBSD.
Fig. 3 is a view showing an ODF showing an unoriented electric steel sheet composed of two types of crystal grains in Fig. 2 as an atchipet structure. Fig.
4 is a view showing an orientation distribution function (ODF) obtained as a result of observing the non-oriented electrical steel sheet according to Inventive Example 8 with an EBSD.
FIG. 5 is a view showing an inverse pole figure and an orientation distribution function (ODF) obtained by observing the non-oriented electrical steel sheet according to the inventive example 11 with the EBSD.
6 is a view showing an inverse pole figure and an orientation distribution function (ODF) obtained by observing the non-oriented electrical steel sheet according to the inventive example 15 with the EBSD.

Hereinafter, the present invention will be described in detail. The following embodiments and drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. In addition, unless otherwise defined in the technical and scientific terms used herein, unless otherwise defined, the meaning of what is commonly understood by one of ordinary skill in the art to which this invention belongs is as follows, A description of known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted. Further, various elements and regions in the drawings are schematically drawn. Accordingly, the technical spirit of the present invention is not limited by the relative size or spacing depicted in the accompanying drawings.

In addition, unless otherwise stated,% means% by weight, and 1 ppm is 0.0001% by weight.

The term "{100} texture" used in the present invention means a plane parallel to the plane of the non-oriented electrical steel sheet. Here, the plate surface of the non-oriented electrical steel sheet means the xy plane when the rolling direction (RD direction) of the steel sheet is the x axis width direction (TD direction) and the y axis. The measurement of {100} texture was performed by EBSD (Electron Backscatter Diffraction) based on ND direction crystal orientation under Rolling, T (Transverse) and N (Vertical) Were calculated and analyzed using an orientation distribution function (ODF).

As used herein, the term "face strength of a {100} texture" refers to the relative strength when referring to intensity 1 of a random texture that does not have any texture. The intensity of a random texture that does not have a texture has been obtained from powdered form of steel. For example, the maximum surface strength of the {100} texture refers to the surface strength of the bearing showing the maximum surface strength among the orientations shown in the orientation distribution function image (ODF image, φ ₂ = 45 ° degree section).

The non-oriented electrical steel sheet according to the present invention minimizes the growth of {111} crystal grains due to the surface segregation of S by controlling the S content to 0.02 wt% or less in the component system containing Si, Mn and Al, So that the magnetic properties can be improved by maximizing the surface strength of the {100} texture.

To this end, the non-oriented electrical steel sheet according to an embodiment of the present invention includes 2.0 to 3.5% of Si, 0.02 to 0.50% of Mn, 0.004% or less of C (excluding 0%), 0.004% or less of N (Excluding 0%), S: not more than 0.001% (excluding 0%), the balance Fe and other unavoidable impurities, the maximum surface strength of the {100} The angle between the crystal direction and the rolling direction is any one of an angle of 0 degree or more and 30 degrees or less or 45 degrees.

The Al added as a resistivity element causes fine nitrides to be formed which cause the magnetism to become dull. In the case of the non-oriented electrical steel plate No. 10-1632890, if the size of the article to be printed is small, the magnetism is deteriorated due to interference with the movement of the magnetic wall, so that the frequency of formation of coarse inclusions needs to be increased. In addition, AlN plays a role of suppressing the growth of crystal grains by fixing the grain boundaries during annealing.

In one embodiment of the present invention, when S is added in a large amount, S is combined with Mn to form MnS to adversely affect the iron loss, and the surface energy of {100} and {110} To promote the growth of crystal grains parallel to the {111} plane to inhibit magnetism.

According to one embodiment of the present invention, the intensity of the {100} plane, which is an aggregate structure parallel to the surface of the sheet, which is preferable for magnetism, is controlled to exceed 30, preferably 30 or more and 100 or less, or 45 or more and 80 or less.

Hereinafter, the alloy composition of the non-oriented electrical steel sheet according to one embodiment of the present invention will be described in detail.

Si: 2.0 to 3.5 wt%

Since Si is a component which increases the specific resistance of the steel and lowers eddies loss during iron loss, it is difficult to obtain low iron loss characteristics when the Si content is less than 2.0%, and plate breakage occurs when the Si content exceeds 3.5% In the invention, Si is limited to 2.0 to 3.5 wt%.

Mn: 0.02 to 0.50%

Since the Mn has the effect of increasing the specific resistance and lowering the iron loss in addition to Si and Al, the conventional non-oriented electrical steel sheet was attempted to improve the iron loss by adding Mn in an amount of at least 0.5%. However, as the Mn addition amount increased, the saturation magnetic flux density The magnetic flux density at the time of application of a constant current decreases. Therefore, in order to improve the magnetic flux density and prevent the increase of iron loss due to inclusions, the amount of Mn added is limited to 0.02 or more and 0.5% or less in one embodiment of the present invention.

C: 0.004% or less (excluding 0%)

When a large amount of C is added, it enlarges the austenite region, increases the phase transformation period, inhibits the crystal growth of ferrite during annealing, increases the iron loss, combines with Ti and forms carbides to dislodge magnetism, , The iron loss is increased by magnetic aging at the time of use after use. Therefore, the content of C is limited to 0.004% or less in the present invention.

S: 0.001% or less (excluding 0%)

S is an element which forms sulfides such as MnS, CuS and (Cu, Mn) S which are harmful to the magnetic properties, and therefore it is known that it is preferable to add S low. However, when S is segregated on the surface of the steel, it has the effect of lowering the surface energy of {100} plane. Therefore, by adding S, a texture having strong {100} plane can be obtained. If the S component of the slab composition according to the present invention is added in an amount exceeding 0.02%, the possibility of breakage of the steel sheet due to the deterioration of the hot and cold rolling characteristics is increased. Therefore, S contained in the slab is not more than 0.02% ). When the cold-rolled steel sheet containing the S component in this range is subjected to the final heat treatment at a temperature of 950 to 1250 캜 for 10 hours or more in the reducing gas atmosphere, due to H ₂ S reaction in the steel sheet and hydrogen in the atmosphere, S remaining in the non-oriented electrical steel sheet becomes 0.001% or less. When the S content is more than 0.001% after the final heat treatment, the S content in the final heat-treated steel sheet is limited to 0.001% or less because the magnetic properties are deteriorated due to the formation of a large amount of MnS precipitates during the cooling process.

N: 0.004% or less (excluding 0%)

N is an element which is detrimental to magnetism such as forming a nitride by binding strongly with Al, Ti or the like to inhibit grain growth, and therefore it is preferable to contain N in a small amount, and in the present invention, N is limited to 0.004 wt% or less.

In addition to the above composition, the remainder is composed of Fe and other unavoidable impurities.

Hereinafter, a method for manufacturing a non-oriented electrical steel sheet according to another embodiment of the present invention will be described in detail.

The non-oriented steel sheet steel slab exhibiting a ferrite phase is reheated to a temperature of 1200 DEG C or less and then hot-rolled in the pre-heat treatment temperature range as described above. If the reheating temperature is higher than 1200 ° C., the precipitates such as MnS present in the slab may be re-precipitated during hot rolling to suppress crystal growth and decrease magnetism, so that the reheating temperature is limited to below 1200 ° C.

Next, the reheated slab is hot-rolled to obtain a hot-rolled sheet.

The hot-rolled sheet prepared as described above is subjected to annealing of a hot-rolled sheet which is heated to 950 to 1150 占 폚, followed by pickling, primary cold-rolling which does not include intermediate annealing, and finally cold-

The hot-rolled sheet annealing is carried out to improve the magnetic properties, and the hot-rolled sheet annealing temperature is set at 950 to 1150 ° C. If the annealing temperature of the hot-rolled sheet is lower than 950 占 폚, grain growth is insufficient, and if it exceeds 1150 占 폚, crystal grains excessively grow and surface defects of the plate become excessive.

The hot-rolled sheet annealed by a conventional method is pickled and then cold-rolled.

The cold rolling is performed by cold rolling at a thickness of 0.05 to 0.3 mm by rotating the annealed hot rolled sheet by 180 degrees in parallel with the plate surface for each pass of the cold rolling and then performing cold rolling, have.

Alternatively, the cold-rolling may be performed at a thickness of 0.05 to 0.3 mm, and the hot-rolled sheet may be subjected to cold rolling at 180 degrees parallel to the sheet surface for each cold rolling pass, followed by cold rolling with intermediate annealing.

In the cold rolling according to an embodiment of the present invention, cold rolling is performed by changing the rolling direction for each pass of the cold rolling. For example, the single-stage cold rolling can be performed a plurality of passes, and one end or the other end of the hot-rolled sheet can be cold-rolled in the rolling direction alternately for each unit pass. That is, the non-oriented electrical steel sheet according to the present invention can improve the magnetic property by efficiently arranging the aggregate structure favorable to magnetism.

Next, the final cold-rolled steel sheet is finally annealed at a temperature of 950 to 1250 캜 to produce a annealed sheet.

If the final annealing is performed at a temperature lower than 950 占 폚, the growth of crystal grains is insufficient and the time required for recrystallization is long, which is difficult to realize in the process. When the temperature exceeds 1250 占 폚, crystal grains grow excessively, It may be finely precipitated during the post-cooling to adversely affect the magnetism.

At this time, it is preferable that the final annealing is performed by heating at a temperature of 10 ° C. to 14400 ° C./h for improving the surface strength and the magnetic property of the {100} texture of the non-oriented electrical steel sheet according to the present invention.

It is preferable that the final annealing is performed at a temperature of 950 to 1250 캜 for 10 hours to 60 hours to improve the surface strength and the magnetic property of the {100} texture of the nonoriented electrical steel sheet according to the present invention.

As described above, the non-oriented electrical steel sheet manufacturing method according to the preferred embodiment of the present invention uses a steel sheet showing a ferrite structure at a preheating temperature range to perform heat treatment in a reducing gas atmosphere instead of a vacuum, 100} crystal orientation can be easily formed.

Thereafter, the annealed sheet is shipped to the customer after the insulating coating treatment. The insulating coating may be treated with an organic, inorganic and organic composite coating, or may be treated with other insulating coatings. The customer can use the steel sheet after processing.

Meanwhile, in the method for manufacturing a non-oriented electrical steel sheet according to a preferred embodiment of the present invention, pre-annealing is performed by heating the cold-rolled sheet to 1000 to 1100 ° C and then cooling the cold- . &Lt; / RTI &gt; When the pre-annealing is carried out, it is possible to have the effect shown by the result of the above-mentioned final annealing.

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

[Example 1]

A slab having the composition shown in Table 1 was heated to 1150 占 폚 and hot-rolled to a thickness of 2.5 mm. The hot-rolled steel sheet cooled in the air was annealed at 1050 ° C for 2 minutes, pickled, and then rolled in a rolling direction of 180 ° for 0.1 mm and 0.2 mm thickness for each cold rolling pass. Final annealing of the cold-rolled sheet was carried out at a heating rate of 50 DEG C / h to 1050 DEG C for 2.5 or 10 hours under a 75% hydrogen + 25% nitrogen atmosphere.

For each specimen, the texture was examined in the area of 5 mm x 12 mm using EBSD, and the iron loss and magnetic flux density were measured in the rolling direction by using a magnetometer. The results are shown in Table 2 below.

[Table 1]

[Table 2]

As shown in Table 2, E1 and E2 steels with 0.2 mm thickness showed relatively low {100} strength.

1 is a view showing an orientation distribution function (ODF) obtained by observing the non-oriented electrical steel sheet according to Comparative Example 2 with an EBSD. Referring to FIGS. 1 and 2, the non-oriented electrical steel sheet according to Comparative Example 2 significantly reduced the {100} strength from 73 to 13 compared with the non-oriented electrical steel sheet according to Example 2, and also had an iron loss of 1.33 to 1.65 And the average crystal grain diameter is 2.25 times the thickness of the non-oriented electrical steel sheet according to Comparative Example 2. Therefore, it can be seen that the preferred average grain diameter is out of the range of 9 to 50 times the thickness of the above- have.

[Example 2]

A slab having the composition shown in Table 1 was heated to 1150 占 폚 and hot-rolled to a thickness of 2.5 mm. The hot-rolled steel sheet cooled in the air was annealed at 1050 ° C for 2 minutes, pickled, and then rolled in a rolling direction of 180 ° for 0.1 mm and 0.2 mm thickness for each cold rolling pass. Final annealing of the cold-rolled sheet was carried out at a heating rate of 200 ° C / h to 1050 ° C and for 2.5 or 10 hours under a 75% hydrogen + 25% nitrogen atmosphere.

For each specimen, the texture was examined in an area of 5 mm x 12 mm using EBSD, and the iron loss and magnetic flux density were measured in the rolling direction using a magnetometer. The results are shown in Table 3 below.

[Table 3]

As shown in Table 3, E1 steel of 0.1 and 0.2 mm thickness showed low {100} strength, but E2 steel showed excellent magnetic properties due to high {100} strength regardless of thickness.

FIG. 2 is an orientation distribution function (ODF) obtained by observing the non-oriented electrical steel sheet according to the third embodiment of the present invention with an EBSD, and FIG. 3 is a graph showing the results of a non- Fig. 8 is a drawing showing an ODF shown by an atchipet structure. Fig. 2 and 3, it can be seen that the non-oriented electrical steel sheet according to Inventive Example 3 exhibits a maximum plane strength of 80 or more at an angle formed by the <001> crystal direction in the {100} texture with the rolling direction at about 26.6 degrees (001) [120] can be found.

[Example 3]

A slab having the composition shown in Table 1 was heated to 1150 占 폚 and hot-rolled to a thickness of 2.5 mm. The hot-rolled steel sheet cooled in the air was annealed at 1050 ° C for 2 minutes, pickled, and then rolled in a rolling direction of 180 ° for 0.1 mm and 0.2 mm thickness for each cold rolling pass. Final annealing of the cold-rolled sheet was carried out at a heating rate of 14400 ° C / h to 1050 ° C for 10 hours under a 75% hydrogen + 25% nitrogen atmosphere.

For each specimen, the texture was examined in the area of 5 mm x 12 mm using EBSD, and the iron loss and magnetic flux density were measured in the rolling direction by using a magnetometer. The results are shown in Table 4 below.

[Table 4]

As shown in Table 4, 0.1 and 0.2 mm thick E1 and E2 steels exhibited excellent magnetic properties due to their high {100} surface strength.

4 is a view showing an orientation distribution function (ODF) obtained by observing the non-oriented electrical steel sheet according to the EXPERIMENTAL EXAMPLE 8 with an EBSD. Referring to FIG. 4, the non-oriented electrical steel sheet according to the inventive example 8 exhibits a maximum surface strength at an angle of 45 degrees with the <001> crystal direction in the {100} [110] can be seen.

[Example 5]

A slab having the composition shown in Table 1 was heated to 1150 占 폚 and hot-rolled to a thickness of 2.5 mm. The hot-rolled steel sheet cooled in air was annealed at 1050 ° C for 2 minutes, pickled, and then cold rolled for one-step cold rolling by rotating the rolling direction by 180 degrees for each cold rolling pass of 0.2 mm thickness. The final annealing of the cold-rolled sheet was carried out at a heating rate of 50 ° C / h to 1100 ° C for 24 hours under a 75% hydrogen + 25% nitrogen atmosphere.

For each specimen, the texture was examined in an area of 5 mm x 12 mm using EBSD, and the iron loss and magnetic flux density were measured in the rolling direction using a magnetometer, and the results are shown in Table 5 below.

[Table 5]

As shown in Table 5, E1 steel of 0.2 mm thickness showed low {100} strength, but E2 steel showed excellent magnetic properties due to relatively high {100} strength.

[Example 5]

A slab having the composition shown in Table 1 was heated to 1150 占 폚 and hot-rolled to a thickness of 2.5 mm. The hot-rolled steel sheet cooled in the air was annealed at 1050 ° C for 2 minutes, pickled, and then rolled in a rolling direction of 180 ° for 0.1 mm and 0.2 mm thickness for each cold rolling pass. The final annealing for the cold-rolled sheet was conducted at a heating rate of 50 ° C / h to 1100 ° C and for 12 hours under a 75% hydrogen + 25% nitrogen atmosphere.

For each specimen, the texture was examined in an area of 5 mm x 12 mm using EBSD, and the iron loss and magnetic flux density were measured in the rolling direction by using a magnetometer. The results are shown in Table 6 below.

[Table 6]

As shown in Table 6, the E2 steel showed excellent magnetic properties due to the strength of {100} plane of 30 or more regardless of the thickness.

5, it can be seen that the non-oriented electrical steel sheet according to Inventive Example 11 exhibits a maximum plane strength of 30 or more at an angle formed by the <001> crystal direction in the {100} texture with the rolling direction at about 23.2 degrees, It can be seen that the specific aggregate organization represents (001) [370]. In addition, a large amount of grains other than {100} texture (red color) are observed.

[Example 6]

A slab having the composition shown in Table 1 was heated to 1150 占 폚 and hot-rolled to a thickness of 2.5 mm. The hot-rolled steel sheet cooled in air was annealed at 1050 占 폚 for 2 minutes, pickled, and then cold rolled in two steps including intermediate annealing in which the rolling direction was rotated 180 degrees for each cold rolling pass to a thickness of 0.1 mm. At this time, after the primary cold rolling, intermediate annealing was performed at 1050 ° C for 2 minutes. The cold rolling reduction rate in the secondary cold rolling was 25% and 75%, and the final annealing for the cold- To 1050 &lt; 0 &gt; C for 12 hours at 1050 &lt; 0 &gt; C and 75% hydrogen + 25% nitrogen.

For each specimen, the texture was examined in the area of 5 mm x 12 mm using EBSD, and the iron loss and magnetic flux density were measured in the rolling direction using a magnetometer. The results are shown in Table 7 below.

[Table 7]

As shown in Table 7, when 25 and 75% secondary cold-rolled steel are heat-treated at 1050 ° C for a long time, most of the steel is composed of {100} crystal grains and excellent magnetic properties are obtained. However, the 75% second cold-rolled E2 steel has a considerable strength on the {110} plane and deteriorates the properties of the molybdenum due to poor <111> crystal orientation in the {110} plane.

[Example 7]

A slab having the composition shown in Table 1 was heated to 1150 占 폚 and hot-rolled to a thickness of 2.5 mm. The hot-rolled steel sheet cooled in air was annealed at 1050 占 폚 for 2 minutes, pickled, and then cold rolled in two steps including intermediate annealing in which the rolling direction was rotated 180 degrees for each cold rolling pass to a thickness of 0.1 mm. At this time, after the primary cold rolling, intermediate annealing was performed at 1050 ° C for 2 minutes, the cold rolling reduction rate at the time of the secondary cold rolling was set at 50%, the final annealing at the cold rolling was performed at a heating rate of 50 ° C / , And the reaction was carried out at 1050 DEG C under a 75% hydrogen + 25% nitrogen atmosphere for 12 hours.

For each specimen, the texture was examined in the area of 5 mm x 12 mm using EBSD, and the iron loss and magnetic flux density were measured in the rolling direction using a magnetometer. The results are shown in Table 8 below.

[Table 8]

As shown in Table 8, when a steel sheet having a thickness of 0.1 mm and a thickness of 0.1 mm is cold-rolled at a temperature of 1050 ° C for a long period of time, most of the steel sheets are composed of a {100} crystal grain and have excellent magnetic properties.

6 is a view showing an orientation distribution function (ODF) obtained by observing the non-oriented electrical steel sheet according to the Inventive Example 15 with an EBSD. Referring to FIG. 6, the non-oriented electrical steel sheet according to Inventive Example 15 exhibits a maximum surface strength at an angle of 0 degree with respect to the <001> crystal orientation in the {100} [010].

[Example 8]

A slab having the composition shown in Table 1 was heated to 1150 占 폚 and hot-rolled to a thickness of 2.5 mm. The hot-rolled steel sheet cooled in the air was annealed at 1050 ° C for 2 minutes, pickled, and then cold-rolled at a thickness of 0.2 mm for each cold rolling pass by 180 degrees in the cold rolling direction. In this case, after the primary cold rolling, intermediate annealing was performed at 1050 ° C. for 2 minutes. The cold rolling reduction rate in the secondary cold rolling was 25%, 50% and 75%, and the final annealing for the cold- Deg.] C / h to 1050 [deg.] C for 24 hours at 1100 [deg.] C under 75% hydrogen + 25% nitrogen.

For each specimen, the texture was examined in the area of 5 mm x 12 mm using EBSD, and the iron loss and magnetic flux density were measured in the rolling direction by using a magnetometer. The results are shown in Table 9 below.

[Table 9]

As shown in Table 9, when 25, 50, and 75% secondary cold-rolled 0.2 mm thick steel sheets are heated at 1050 ° C. for a long period of time, most of the steel sheets are composed of {100} crystal grains and have excellent magnetic properties. However, the strength of the {110} plane is considerably higher for 75% two-stage cold-rolled E2 steel. Therefore, the characteristics of the high-performance magnetic core are deteriorated due to the <111> crystal orientation in the {110} plane having poor magnetic properties.

[Example 9]

A slab having the composition shown in Table 1 was heated to 1150 占 폚 and hot-rolled to a thickness of 2.5 mm. The hot-rolled steel sheet cooled in air was annealed at 1050 ° C for 2 minutes, pickled, and then rolled in a rolling direction of 180 degrees for each cold rolling pass to a thickness of 0.1 mm, followed by one-step cold rolling. The final annealing for the cold-rolled sheet was performed at a heating rate of 50 ° C / h up to 1050 ° C and pre-annealing was performed at 3050 ° C for 60 seconds in a nitrogen atmosphere of 75% hydrogen + 25% 120 seconds and 300 seconds, and heating was carried out at 1050 占 폚 at a heating rate of 50 占 폚 / h in the same heat treatment atmosphere, followed by 10 hours at that temperature.

For each specimen, the texture was examined in an area of 5 mm x 12 mm using EBSD, and the iron loss and magnetic flux density were measured in the rolling direction by using a magnetometer. The results are shown in Table 10 below.

[Table 10]

As shown in Table 10, the E1, E2 and E3 steel grades of 0.1 mm thickness exhibited excellent magnetic properties due to the high {100} surface irrespective of the preheating temperature time.

As described above, the non-oriented electrical steel sheet according to an embodiment of the present invention has a maximum plane strength of {100} texture of not less than 30 and a direction of <001> crystal in {100} Direction is in the range of 0 to 30 degrees or 45 degrees. In particular, the non-oriented electrical steel sheet according to an embodiment of the present invention has a maximum surface strength of {110} texture of 0 or less. Accordingly, since the non-oriented electrical steel sheet according to the present invention shows almost no {110} texture and has a maximum surface strength of 30 or more, the magnetic properties of the non-oriented electrical steel sheet are excellent when the high- Can be maintained.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (7)

0.004% or less (excluding 0%), N: 0.004% or less (excluding 0%), S: 0.001% or less (0% , The remainder Fe and other unavoidable impurities,
The maximum surface strength of {100} texture is over 30,
Wherein the angle formed by the <001> crystal orientation in the {100} texture representing the maximum face strength with the rolling direction is any one of an angle of 0 to 30 degrees or an angle of 45 degrees.
The method according to claim 1,
Wherein the thickness of the electrical steel sheet is 0.05 to 0.3 mm.
3. The method of claim 2,
The average grain diameter of the steel sheet
Wherein the thickness of the non-oriented electrical steel sheet is 9 to 50 times the thickness of the electrical steel sheet.
a) 0.001% or less (excluding 0%), N: 0.004% or less (excluding 0%), S: 0.02% or less (in terms of% by weight, Si: 2.0 to 3.5%, Mn: 0.02 to 0.50% 0% is excluded), reheating the slab containing the remaining Fe and other unavoidable impurities to 1200 占 폚 or less;
b) hot rolling the reheated slab to obtain a hot rolled sheet;
c) annealing the hot-rolled sheet by heating the hot-rolled sheet to 950 to 1150 캜 and then cooling it;
d) cold-rolling the annealed hot-rolled sheet to a two-stage cold-rolled sheet including one-stage cold rolling or intermediate annealing not including intermediate annealing to obtain a cold-rolled sheet; And
e) final annealing the cold-rolled sheet in a reducing gas atmosphere at 950 to 1250 占 폚.
5. The method of claim 4,
In the step e)
Wherein the final annealing is performed at a temperature of 10 to 14400 DEG C / h.
6. The method of claim 5,
In the step e)
Wherein the final annealing is performed at the temperature for 10 to 60 hours.
5. The method of claim 4,
Between step d) and step e)
And performing pre-annealing in which the cold-rolled sheet is heated to 1000 to 1100 캜 and then cooled.

Images