KR101648334B1 - Non-oriented electrical steel sheet and method for manufacturing the same - Google Patents

Abstract

The non-oriented electrical steel sheet according to one embodiment of the present invention comprises 1.0 to 3.5% of Si, 0.03% or less of Al, 0.01 to 1.50% of Mn, 0.001 % To 0.15%, S: 0.001% to 0.01%, the remainder including Fe and other unavoidable impurity elements.

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 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, the same magnetic flux density can be obtained even if a smaller current is applied, so that heat loss caused by the copper wire wound can be reduced, and the higher the magnetic flux density characteristic is, the better.

In order to improve the iron loss 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 large resistivity, is generally used for increasing the electrical resistance. 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.

Moreover, if the amount of addition of silicon (Si) and aluminum (Al) increases, the workability is lowered, which makes it difficult to perform cold rolling, resulting in deteriorated productivity and increased hardness, resulting in poor workability.

The method that is effectively used for the improvement of the aggregate structure is known as a method of adding a trace alloy 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.
BACKGROUND ART 1: Published patent publication No. 10-2009-0014383
BACKGROUND ART 2: Published Patent Publication No. 10-2008-0027913

An embodiment of the present invention is to provide a non-oriented electrical 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 comprises 1.0 to 3.5% of Si, 0.03% or less of Al, 0.01 to 1.50% of Mn, 0.001 % To 0.15%, and S: 0.001% to 0.01%, the remainder including Fe and other unavoidable impurity elements, wherein the value of [Al] / [S]

In addition, the value of [Al] / [S] in the non-oriented electrical steel sheet may be 3 or less. (Where [Al] and [S] are amounts of Al and S added (weight%), respectively)

The electrical steel sheet may further contain 0.004 wt% or less of C, 0.004 wt% or less of N, 0.004 wt% or less of Ti, and 0.004 wt% or less of Mg.

Further, the electrical steel sheet may further include Sn and Sb, and the value of [Sn] + [Sb] + [P] may be 0.03 wt% to 0.35 wt%. ([Sn], [Sb], and [P] are addition amounts (% by weight) of Sn, Sb and P, respectively)

The electrical steel sheet may further contain 0.05 wt% or less of Cu, Ni, or Cr, respectively, and may further contain 0.01 wt% or less of Zr, Mo, or V, respectively.

In addition, the average value of the grain size of the grain of the non-oriented electrical steel sheet may be 60 탆 to 300 탆.

A method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention comprises: providing a slab including 1.0 to 3.5% of Si, 0.03% or less of Al, 0.01 to 1.50% of Mn, : 0.001% to 0.15%, S: 0.001% to 0.01%, the remainder comprising Fe and other unavoidable impurity elements, wherein the value of [Al] / [S] is 3 or less; Heating the slab and then hot rolling to produce a hot rolled sheet; Cold-rolling the hot-rolled sheet to produce a cold-rolled sheet; And finally annealing the cold-rolled sheet.

(Where [Al] and [S] are amounts of Al and S added (weight%), respectively)

The slab may further contain 0.004 wt% or less of C, 0.004 wt% or less of N, 0.004 wt% or less of Ti, and 0.004 wt% or less of Mg.

The slab further includes Sn and Sb, and the value of [Sn] + [Sb] + [P] may be 0.03 wt% to 0.35 wt%. ([Sn], [Sb], and [P] are weight percentages of Sn, Sb and P, respectively)

The slab may further contain 0.05 wt% or less of Cu, Ni, or Cr, respectively, and may further contain 0.01 wt% or less of Zr, Mo, or V, respectively.

The final annealing temperature may be 800 캜 or higher and 1230 캜 or lower.

The average value of the grain sizes of the crystal grains grown by the final annealing may be 60 탆 to 300 탆.

Further comprising the step of annealing the hot-rolled sheet after the hot-rolling, wherein the annealing temperature of the hot-rolled sheet may be 900 to 1180 占 폚.

According to an embodiment of the present invention, a non-oriented electrical steel sheet having low iron loss and excellent magnetic flux density can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction 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.

Thus, in some embodiments, well-known techniques are not specifically described to avoid an undesirable interpretation of the present invention. Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Whenever a component is referred to as "including" an element throughout the specification, it is to be understood that the element may include other elements, not the exclusion of any other element, unless the context clearly dictates otherwise. Also, singular forms include plural forms unless the context clearly dictates otherwise.

Unless otherwise stated,% means weight%.

The non-oriented electrical steel sheet according to one embodiment of the present invention comprises 1.0 to 3.5% of Si, 0.03% or less of Al, 0.01 to 1.50% of Mn, 0.001 % To 0.15%, and S: 0.001% to 0.01%, the remainder including Fe and other unavoidable impurity elements.

In addition, the value of [Al] / [S] in the non-oriented electrical steel sheet may be 3 or less. Here, [Al] and [S] are amounts of Al and S added (% by weight), respectively.

The electrical steel sheet may further contain 0.004 wt% or less of C, 0.004 wt% or less of N, 0.004 wt% or less of Ti, and 0.004 wt% or less of Mg.

Further, the electrical steel sheet may further include Sn and Sb, and the value of [Sn] + [Sb] + [P] may be 0.03 wt% to 0.35 wt%. Here, [Sn], [Sb] and [P] are amounts of Sn, Sb and P added (weight%), respectively.

The electrical steel sheet may further contain 0.05 wt% or less of Cu, Ni, or Cr, respectively, and may further contain 0.01 wt% or less of Zr, Mo, or V, respectively.

First, the reason for the limitation of the element is described.

Si is a component that lowers the eddy loss by increasing the resistivity. When the content of Si is less than 1.0%, it is difficult to obtain low iron loss characteristics, and when it exceeds 3.5%, plate breakage may occur during cold rolling.

Mn has the effect of lowering the iron loss by increasing the resistivity, but the saturation flux density decreases as the addition amount is increased. Therefore, in order to improve the magnetic flux density and prevent the increase of iron loss due to inclusions, the Mn addition amount may be 0.01 to 1.5% in one embodiment of the present invention. More specifically, it may be 0.03% to 1.50%, 0.03% to 0.5%.

The Al resistivity can be increased and the rolling property can be improved. However, when it exceeds 0.03%, the saturation magnetic flux density can be decreased and the fine AlN can be formed to lower the magnetism.

P is added in an amount of 0.001% or more to increase the resistivity, lower the iron loss, inhibit the formation of {111} texture, and promote the formation of {100} texture. However, if it exceeds 0.15%, the rolling property may be lowered.

If C is more than 0.004%, the grain growth of the ferrite can be suppressed to increase the iron loss upon annealing, and the iron can be bonded with Ti or the like to dislocate the magnetism.

N may not be added because it is an element harmful to magnetism such as inhibiting grain growth by bonding with Al, Ti, etc. However, it may be 0.004% or less considering the amount that is inevitably incorporated during the steelmaking process.

S is segregated on the surface of the steel to lower the surface energy of the {100} plane to obtain a texture having a strong {100} plane. If it is less than 0.001%, the formation of aggregate structure may be disadvantageous and the magnetic property may be deteriorated. If it exceeds 0.01%, precipitates may be greatly increased and adversely affect magnetism.

Ti forms fine carbides and nitrides to inhibit crystal growth. As the amount of Ti is increased, the magnetization becomes poor due to the increase of carbides and nitrides, resulting in a dislocation of the texture. Therefore, it can be 0.004% or less.

Mg may form Mg ₂ S, Mg ₂ Sn and the like to precipitate finely, which may adversely affect magnetism, and therefore may be 0.004% or less.

Sn and Sb segregate in the grain boundaries, suppressing the diffusion of nitrogen through grain boundaries, inhibiting the {111} texture and increasing {100} texture. If the value of [Sn] + [Sb] + [P] is less than 0.03% by weight, the effect of improving the magnetic properties due to the increase in {100} texture can not be exhibited. ([Sn], [Sb], and [P] are weight percentages of Sn, Sb and P, respectively)

Cu, Ni, and Cr may form fine sulfides, carbides, and nitrides, which may have detrimental effects on the magnetic properties. Therefore, the respective contents may be limited to 0.05 wt% or less.

Further, since Zr, Mo, and V form a carbonitride, the respective contents can be 0.01% by weight or less.

In addition to the above-mentioned elements, any element on the periodic table can be introduced into the electrical steel sheet as an impurity, and is included in an amount of 0.004% by weight or less for each element. If it exceeds 0.004%, the magnetic properties of the electrical steel sheet may be affected by impurities.

Further, the value of [Al] / [S] may be 3 or less. More specifically from 0.14 to 3. When the value of [Al] / [S] is 0.14 to 3, the formation of {111} texture is low and the formation of {100} and {110} texture is improved and the magnetism can be improved. Also, when the value of [Al] / [S] is more than 3, the saturation magnetic flux density is reduced and fine AlN is formed to suppress the grain growth and decrease the magnetism.

In addition, the average value of the grain size of the grain of the non-oriented electrical steel sheet may be 60 탆 to 300 탆. If the average value of the grain size of the crystal grains is less than 60 탆, the crystal growth may be insufficient and the magnetism may be deteriorated. If the average grain size exceeds 300 탆, the iron loss characteristics may be lowered in the high frequency region.

Hereinafter, a method for producing the non-oriented electrical steel sheet according to the present invention will be described.

First, a steel slab having a slab content of 1.0 to 3.5%, Al of 0.03% or less, Mn of 0.01 to 1.50%, P of 0.001 to 0.15% and S of 0.001 to 0.01% % And the remainder comprises Fe and other unavoidable impurity elements, wherein the value of [Al] / [S] is 3 or less. (Where [Al] and [S] are the addition amounts (% by weight) of Al and S, respectively)

The slab may further contain 0.004 wt% or less of C, 0.004 wt% or less of N, 0.004 wt% or less of Ti, and 0.004 wt% or less of Mg.

The slab further includes Sn and Sb, and the value of [Sn] + [Sb] + [P] may be 0.03 wt% to 0.35 wt%. ([Sn], [Sb], and [P] are weight percentages of Sn, Sb and P, respectively)

The slab further contains 0.05 wt% or less of Cu, Ni, and Cr, respectively, and may further contain 0.01 wt% or less of Zr, Mo, and V, respectively.

The other unavoidable impurity elements may be included in an amount of 0.004% by weight or less for each element.

The reason for limiting the constituent elements in the slab is the same as the reason for limiting the constituent elements in the electric steel sheet.

The slab of the base material is heated at a temperature of 1230 캜 or lower and hot rolled to produce a hot rolled sheet. When the slab heating temperature is higher than 1230 ° C, precipitates such as AlN and MnS existing in the slab may be dissolved and then precipitated finely during hot rolling.

Finishing rolling in hot rolling finishes when the steel sheet is in ferrite phase, and the reduction rate is 20% or less for the plate shape calibration, and the thickness of the final plate may be 2.8 mm or less. When the rolling on the ferrite is terminated as described above, many {100} planes are formed and the magnetic property can be improved.

The hot-rolled sheet may be subjected to hot-rolled sheet annealing as needed for improving the magnetic properties. When the hot-rolled sheet annealing is carried out, the annealing temperature may be 900 ° C to 1180 ° C. If there is no austenite-ferrite phase transformation during the hot rolling, the annealing temperature may be 1000 ° C to 1180 ° C. When the annealing temperature of the hot-rolled sheet is less than 900 캜, the crystal growth is insufficient. When the annealing temperature exceeds 1180 캜, the crystal grains excessively grow and the surface defects of the plate may become excessive.

The hot-rolled sheet is cold-rolled to produce a cold-rolled sheet. The cold rolling may be performed by cold rolling one time to the final thickness, or by cold rolling twice or more including intermediate annealing at least once.

It can be cold-rolled to a final thickness of 0.10 mm to 0.70 mm by cold rolling.

The cold-rolled cold-rolled sheet is subjected to final annealing.

The final annealing can be performed by annealing at a temperature of 800 占 폚 or higher and 1230 占 폚 or lower for 10 seconds or longer to be annealed.

Hereinafter, 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 slabs having the compositions shown in Table 1 were heated to 1150 占 폚. Thereafter, it was hot rolled to a thickness of 2.5 mm and rolled at 650 ° C. The hot-rolled steel sheet cooled in air was annealed at 1100 ° C for 3 minutes, pickled, and then cold-rolled to a thickness of 0.35 mm. Thereafter, the cold-rolled sheet was finally annealed at an annealing temperature of 1050 DEG C for 60 seconds.

Steel grade C Si Mn Mg P S Al N Ti Sn Sb A1 25 1.45 0.13 10 0.13 32 0.006 12 14 0.051 0.034 A2 15 1.53 0.03 6 0.035 51 0.002 15 9 0.071 0 A3 33 2.51 0.5 54 0.065 68 0.035 34 14 0 0.052 A4 23 2.03 0.09 45 0.012 12 0.015 27 12 0 0 A5 31 2.54 0.03 45 0.009 48 0.3 23 16 0.015 0 A6 11 2.09 0.25 32 0.003 21 0.8 25 19 0.012 0.015 A7 23 2.51 0.51 51 0.005 235 0.005 12 14 0 0.021 A8 32 3.3 0.16 21 0.025 56 0.002 23 12 0.031 0.011 A9 13 3.23 0.27 2 0.078 62 0.006 14 17 0.034 0.031 A10 21 2.08 0.19 3 0.05 58 0.006 23 12 0.051 0.053 A11 17 2.14 0.15 5 0.092 47 0.003 18 18 0.056 0.065 A12 29 2.13 0.35 3 0.035 72 0.001 21 7 0.043 0.051 A13 37 2.1 0.03 4 0.015 52 0.006 27 12 0.061 0 A14 28 2.3 0.05 5 0.045 43 0.004 29 2 0.031 0.051 A15 21 0.5 0.32 31 0.035 51 0.016 37 12 0.041 0.023 A16 25 1.3 0.13 45 0.054 98 0.06 35 14 0.031 0.033

In Table 1, the unit of the component content is% by weight. However, the units of C, Mg, S, N and Ti are ppm by weight. Here, ppm means 0.0001 wt%.

Steel grade ({100} + {110}) / {111} [Al] / [S] Slab
Reheating temperature (℃) After hot rolling
Plate thickness,
mm Hot-rolled plate
Annealing temperature (캜) Number of cold rolling A1 0.6 1.88 1150 2.500 850 One A2 2 0.39 1150 2.500 1000 One A3 1.2 5.2 1150 2.500 1150 One A4 0.5 12.5 1200 3.000 1050 One A5 0.4 63 1200 3.000 1050 One A6 0.2 381 1200 2.500 1050 One A7 0.8 0.21 1200 2.500 1050 One A8 1.1 0.36 1100 2.500 Smiling One A9 1.5 0.97 1150 2.500 1130 One A10 2.1 1.03 1200 2.500 1130 One A11 1.8 0.64 1200 2.500 1130 One A12 2.3 0.14 1200 2.000 1100 One A13 4.1 1.15 1200 2.000 1100 2 A14 8.1 0.93 1150 2.000 1100 3 A15 0.3 3.14 1150 2.500 Smiling One A16 1.2 6.12 1250 2.500 Smiling One

In Table 2, {100}, {110}, and {111} indicate the volume fraction of crystal grains parallel to the plane of the electrical steel sheet within 15 ° of each {100}, {110} . It was measured by using X-ray or EBSD on the plate after final annealing, and by usual method of calculating by ODF in X-ray measurement. In both methods, the measurement area was 1 cm ² or more.

Steel grade Cold rolled plate
Thickness, mm Final annealing
Crack temperature,
℃ Crack time, sec _Iron loss W _15/50,
W / kg Magnetic flux density
B _50, T Remarks A1 0.50 850 15 4.12 1.683 Comparative Example A2 0.50 850 15 3.5 1.765 Honor A3 0.50 1000 15 3.73 1.730 Comparative Example A4 0.50 1000 20 3.65 1.680 Comparative Example A5 0.50 1000 20 3.52 1.656 Comparative Example A6 0.35 1000 20 3.35 1.663 Comparative Example A7 0.35 1050 15 3.52 1.693 Comparative Example A8 0.35 1050 15 2.65 1.615 Comparative Example A9 0.35 1050 15 2.23 1.742 Honor A10 0.35 1000 5 3.26 1.759 Honor A11 0.35 1000 20 2.51 1.747 Honor A12 0.35 1000 20 2.62 1.738 Honor A13 0.25 1000 20 2.15 1.795 Honor A14 0.25 1000 20 2.04 1.812 Honor A15 0.50 850 15 6.3 1.720 Comparative Example A16 0.50 850 15 4.95 1.734 Comparative Example

Iron loss (W15 / 50) is the average loss (W / kg) in the rolling direction and in the direction perpendicular to the rolling direction when magnetic flux density of 1.5 Tesla is induced at 50 Hz frequency.

The magnetic flux density B50 is the magnitude of the magnetic flux density Tesla when a magnetic field of 5000 A / m is added.

As shown in the above table, it can be seen that the specimen satisfying the range according to one embodiment of the present invention has excellent magnetic flux density and iron loss characteristics.

[Example 2]

0.002% of Al, 0.002% of N, 0.001% of Ti, 0.001% of Ti, 0.0004% of Mg, And the remaining Fe and other unavoidable impurities. The slab was heated to 1180 캜, and then subjected to finish rolling under the same conditions as in Table 3 to obtain a hot-rolled steel sheet having a thickness of 2.0 mm, followed by winding at 650 캜 and cooling in air.

Thereafter, annealing was performed for 5 minutes under the conditions shown in Table 4, pickling, cold-rolling to a thickness of 0.35 mm, and final annealing for one minute at 90% by volume of nitrogen and 10% by volume of hydrogen.

division Annealing temperature of hot-rolled sheet
(° C) Final annealing temperature
(° C) Crystal grain
Average Size (탆) Iron loss
(W _15/50)
(W / kg) Magnetic flux density
B ₅₀ {100} + {110} / {111} Inventory 1 1150 1050 195 2.2 1.79 1.52 Inventory 2 1050 1050 154 2.6 1.78 1.37 Inventory 3 1000 900 63 3.8 1.78 1.11 Comparative Example 1 1000 790 54 4.5 1.75 0.95 Comparative Example 2 850 900 48 5.4 1.70 0.65

In Table 4, {100}, {110}, and {111} represent the volume fraction of crystal grains parallel to the plane of the electrical steel sheet within 15 ° of each {100}, {110} . It was measured by X-ray or EBSD on the plate after final annealing, and by the usual method of calculating by ODF for X-ray measurement. In both methods, the measurement area was at least 1 cm ² .

As shown in the above table, it can be seen that the iron loss is low and the magnetic flux density is excellent in the electric steel sheet having the average size of the grains contained in the range of the present invention by controlling the annealing temperature and the annealing time.

While the present invention has been described in connection with certain exemplary embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

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 (13)

Wherein the steel sheet comprises 1.0 to 3.5% of Si, 0.03% or less (excluding 0%) of Al, 0.01 to 1.50% of Mn, 0.001 to 0.15% of P, S: 0.001% to 0.01%, the remainder including Fe and other unavoidable impurity elements, wherein the value of [Al] / [S] is 3 or less,
({100} + {110}) / {111} of not less than 1.11.
(Where [Al] and [S] are the addition amounts (% by weight) of Al and S, respectively,
{100}, {110}, and {111} mean volume fractions of crystal grains in which the faces of {100}, {110}, and {111} orientations in each plate surface are parallel to the plate surface of the electrical steel sheet within 15 °,
The plate surface of the electric steel sheet means the rolling direction of the electric steel sheet, and the x-axis width direction is the y-axis.
The method according to claim 1,
Wherein the electrical steel sheet further contains 0.004 wt% or less of C, 0.004 wt% or less of N, 0.004 wt% or less of Ti, and 0.004 wt% or less of Mg.
3. The method of claim 2,
Wherein the electrical steel sheet further comprises Sn and Sb,
And the value of [Sn] + [Sb] + [P] is 0.03 wt% to 0.35 wt%.
([Sn], [Sb], and [P] are amounts of Sn, Sb, and P added,
The method of claim 3,
Wherein the electrical steel sheet further contains Cu, Ni and Cr in an amount of 0.05 wt% or less, respectively;
Zr, Mo, and V in an amount of 0.01 wt% or less, respectively.
5. The method according to any one of claims 1 to 4,
Wherein the average value of the grain size of the grain of the non-oriented electrical steel sheet is 60 mu m to 300 mu m.
delete Al: 0.03% or less (excluding 0%), Mn: 0.01 to 1.50%, P: 0.001 to 0.15%, S: 0.001 % To 0.01%, the remainder comprising Fe and other inevitable impurity elements, wherein the value of [Al] / [S] is 3 or less;
Heating the slab and then hot rolling to produce a hot rolled sheet;
Annealing the hot-rolled sheet at 900 to 1180 占 폚;
Cold-rolling the hot-rolled sheet to produce a cold-rolled sheet; And;
And finally annealing the cold-rolled sheet at 800 ° C to 1230 ° C,
(100) + {110} / {111} of not less than 1.11 is produced.
(Where [Al] and [S] are amounts of Al and S added (wt%), respectively,
{100}, {110}, and {111} mean volume fractions of crystal grains in which the faces of {100}, {110}, and {111} orientations in each plate surface are parallel to the plate surface of the electrical steel sheet within 15 °,
The plate surface of the electric steel sheet means the rolling direction of the electric steel sheet, and the x-axis width direction is the y-axis.
8. The method of claim 7,
Wherein the slab further contains C: 0.004 wt% or less, N: 0.004 wt% or less, Ti: 0.004 wt% or less, and Mg: 0.004 wt% or less.
9. The method of claim 8,
The slab further includes Sn and Sb,
Wherein the value of [Sn] + [Sb] + [P] is 0.03 wt% to 0.35 wt%.
([Sn], [Sb], and [P] are amounts of Sn, Sb, and P added,
10. The method of claim 9,
The slab further contains not more than 0.05% by weight of Cu, Ni and Cr, respectively;
Zr, Mo, and V in an amount of 0.01 wt% or less, respectively.
delete 11. The method of claim 10,
Wherein an average value of grain sizes of the crystal grains grown by the final annealing is 60 mu m to 300 mu m. delete