KR102464576B1 - Non-oriented electrical steels and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a non-oriented electrical steel sheet and a manufacturing method thereof. The non-oriented electrical steel sheet has improved high tensile strength and magnetic properties by controlling a cold rolling process and heat treatment time in a short time so that addition of Mn, which has a small effect on increasing tensile strength per weight%, is minimized, high tensile strength is maintained by maximizing the amount of Al added, which has a large effect on increasing tensile strength, the surface strength of the {100} texture, which is excellent in magnetic properties, among crystal grains in the steel sheet is increased, and an average grain size is properly adjusted so as not to harm the effect of increasing the tensile strength. The non-oriented electrical steel sheet includes more than 2.6 wt% and less than 4 wt% of Si, more than 0.6 wt% and less than 2 wt% of Al, more than 0.001 wt% and less than 0.005 wt% of Nb, less than 0.1 wt% (excluding 0 wt%) of Mn, etc.

Description

Non-oriented electrical steels and method for manufacturing the same

The present invention relates to a non-oriented electrical steel sheet, and more particularly, by minimizing the addition amount of Mn having a small effect of increasing the tensile strength per weight %, and maximizing the amount of adding Al having a large effect of increasing the tensile strength to maintain high tensile strength, High tensile strength and magnetic properties are improved by controlling the cold rolling process and heat treatment time to be short so that the average grain size can be appropriately adjusted so as not to impair the effect of increasing the tensile strength while increasing the surface strength of the {100} texture, which is excellent in magnetic properties among grains. It relates to a non-oriented electrical steel sheet and a method for manufacturing the same.

The reason that the characteristics of non-oriented electrical steel sheet plays an important role in determining the energy efficiency of electrical equipment is that non-oriented electrical steel sheet is used as a material for iron cores in rotating equipment such as motors and generators, and stationary equipment such as small transformers. to convert it into mechanical energy.

The magnetic properties of the electrical steel sheet include iron loss and magnetic flux density. Since iron loss is energy loss, the lower the better. On the other hand, the magnetic flux density indicates the degree of magnetization under an external magnetic field. If the magnetic flux density is high, the same magnetic flux density can be obtained even when a smaller current is applied. The higher the better.

In general, Si, Al, Mn, etc., which have a large effect of increasing electrical resistance and specific resistance, are added to reduce iron loss among the magnetic properties of non-oriented electrical steel sheets. For Si, Al, and Mn, the effect of increasing the specific resistance per weight % is the largest for Si, the smallest for Mn, and a moderate effect for Al.

In addition, in the texture, it is preferable to increase the {100} surface strength including the crystal direction of <100> easy magnetization and lower the {111} surface or {211} surface strength to increase the magnetic flux density and lower the iron loss.

0.5이다. 따라서, 피로강도를 높이기 위해서는 결정립 크기가 작아야 하는데, 냉연판을 장시간 소둔시, {100}면이 {111}과 {110} 결정립들을 잠식하면서 성장하기 때문에, {100} 집합조직의 면강도가 90%이상으로 증가하더라도, 평균 결정립 크기가 극도로 조대화되기 때문에 상기에 기술된 피로강도 저하를 피할 수 없다. 따라서, 피로강도를 높이기 위해서는 냉연판 최종 열처리 온도에서 열처리 시간을 짧게 하여 결정립 크기를 무한정 작게 하여야 하나, 이러한 경우 짧은 열처리 시간으로 인해 {100} 결정립들에 의한 {111}과 {110} 결정립들의 잠식시간이 너무 짧기 때문에 자성특성에 유리한 {100} 집합조직의 면강도는 감소할 수 밖에 없다.In recent years, in the trend of increasing power of electric vehicle driving motors, efforts are being made to improve not only the magnetic properties of the motor core but also the fatigue strength by increasing the tensile strength. In general, it is a well-known fact that hardness, tensile strength, and fatigue limit (fatigue limit) increase as the grain size (diameter) in the metal decreases (Non-Patent Document 1-3). Here, fatigue strength/tensile strength

0.5. Therefore, in order to increase the fatigue strength, the grain size should be small. When the cold-rolled sheet is annealed for a long time, the {100} plane grows while encroaching on the {111} and {110} grains, so the surface strength of the {100} texture is 90. % or more, the fatigue strength reduction described above cannot be avoided because the average grain size becomes extremely coarse. Therefore, in order to increase fatigue strength, it is necessary to shorten the heat treatment time at the final heat treatment temperature of the cold rolled sheet to make the grain size infinitely small. In this case, the {111} and {110} grains are eroded by the {100} grains due to the short heat treatment time. Since the time is too short, the surface strength of the {100} texture, which is advantageous for magnetic properties, is inevitably reduced.

Therefore, in order to achieve this objective at the same time, the surface strength of the {100} texture advantageous for magnetic properties is secured by appropriately adjusting the average grain size, and the tensile strength must be maximized by minimizing the Mn addition amount and maximizing the Al addition amount. .

Non-patent document 1: N.J. Petch, “The cleavage strength of polycrystals,” J. Iron and Steel Inst., 1953 pp. 25-28. Non-Patent Document 2: Geon-Ho Kim, "Effect of grain size on fatigue crack propagation behavior of low-carbon steel (SM25C)," Journal of the Korean Society for Mechanical Engineers Park, 2002, pp. 76-81. Non-Patent Document 3: "Heat Treatment of Steel", Mechanism Research History, 1979 page 189

The present invention has been devised to solve the above problems, and more specifically, secures the surface strength of the {100} texture to be advantageous for magnetic properties among the grains in the steel sheet, and appropriately adjusts the average grain size, Mn An object of the present invention is to provide a non-oriented electrical steel sheet having high tensile strength and excellent magnetic properties by minimizing the addition amount and maximizing the Al addition amount, and a method for manufacturing the same.

Non-oriented electrical steel sheet according to an embodiment of the present invention by weight%, Si: more than 2.6% 4% or less, Al: more than 0.6% 2% or less, Nb: more than 0.001% 0.005% or less, Mn: less than 0.1% ( excluding 0%), S: less than 0.01% (excluding 0%), C: less than or equal to 0.004% (excluding 0%), N: less than or equal to 0.004% (excluding 0%), P: less than 0.01% (excluding 0%), V: less than 0.005% (excluding 0%), Mo: less than 0.003% (excluding 0%), Ti: less than 0.03% (excluding 0%), Sb: less than 0.015% (excluding 0%), Sn: less than 0.005% ( excluding 0%), Cu: 0.04% by weight or less (excluding 0%), Bi: less than 0.0005% (excluding 0%), As: less than 0.0005% (excluding 0%), Ga: less than 0.002% (excluding 0%), O: 0.005% or less (excluding 0%) and the remainder including Fe and other unavoidable impurities, but may be characterized by satisfying the following Relations 1, 2, 3 and 4.

[Relational Expression 1]

[Sb]+[Sn]+[P]<0.02 (excluding 0)

[Relational Expression 2]

[Bi]+[Ga] < 0.002 (excluding 0)

[Relational Expression 3]

3 ≤ {100} _max ≤ 10

[Relational Expression 4]

0 ≤ ({110} _max /{100} _max ) ≤ 1.5

(In Relations 1 and 2, [Sb], [Sn], [P], [Bi] and [Ga] represent the contents (% by weight) of Sb, Sn, P, Bi and Ga, respectively,

In Relations 3 and 4, {100} _max and {110} _max are the maximum sets of {100} or {110} textures in which the {100} or {110} orientation is parallel to the steel plate within 15° It represents the tissue strength, and the steel sheet surface means the xy surface when the rolling direction of the electrical steel sheet is the x-axis and the width direction is the y-axis.)

In the non-oriented electrical steel sheet according to an embodiment of the present invention, the tensile strength in the rolling direction may be 485 MPa or more.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, the magnetic flux density (B ₅₀ ) in the rolling direction may be 1.60 Tesla or more.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, the iron loss in the rolling direction (W _15/50 ) may be 2.40 W/kg or less.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, the average grain size after final annealing may be 70 to 350 ㎛.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, Si, Al, Nb, Mn, S, C, N, P, V, Mo, Ti, As, Sb, Sn, Cu, Bi, Ga, O And the total amount of the remaining element components other than Fe may be 1% or less.

The non-oriented electrical steel sheet manufacturing method according to an embodiment of the present invention is a) in weight %, Si: more than 2.6% and less than 4%, Al: more than 0.6% and less than or equal to 2%, Nb: more than 0.001% and less than or equal to 0.005%, Mn: Less than 0.1% (excluding 0%), S: Less than 0.01% (excluding 0%), C: Less than 0.004% (excluding 0%), N: Less than 0.004% (excluding 0%), P: Less than 0.01% (0%) %), V: less than 0.005% (excluding 0%), Mo: less than 0.003% (excluding 0%), Ti: less than 0.03% (excluding 0%), Sb: less than 0.015% (excluding 0%), Sn: Less than 0.005% (excluding 0%), Cu: less than 0.04 wt% (excluding 0%), Bi: less than 0.0005% (excluding 0%), As: less than 0.0005% (excluding 0%), Ga: less than 0.002% (0%) %), O: heating the slab containing 0.005% or less (excluding 0%) and the remainder of Fe and other unavoidable impurities to 1200° C. or less; b) preparing a hot-rolled sheet by hot-rolling the heated slab; c) cold-rolling the hot-rolled sheet to manufacture a cold-rolled sheet; and d) final annealing of the cold-rolled sheet to produce a non-oriented electrical steel sheet that satisfies the above Relations 1, 2, 3 and 4.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, the cold-rolled sheet final annealing temperature may be 860 to 1150 °C.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, the final annealing time of the cold-rolled sheet may be 15 to 300 seconds.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, the cold-rolled sheet final annealing atmosphere may be a reducing or non-oxidizing atmosphere.

As described above, according to the non-oriented electrical steel sheet and its manufacturing method according to the present invention, the surface strength of the {100} texture is secured to be advantageous for magnetic properties among the grains in the steel sheet, the grain size is appropriately adjusted, and the tensile strength It is possible to provide a non-oriented electrical steel sheet excellent in fatigue strength and magnetic properties and a method for manufacturing the same by minimizing the amount of Mn added and maximally increasing the amount of Al to maximize the amount of Mn.

On the other hand, even if it is an effect not explicitly mentioned herein, it is added that the effects described in the following specification expected by the technical features of the present invention and their potential effects are treated as described in the specification of the present invention.

1 is an orientation distribution function (ODF) for a steel sheet final annealed according to Example 6.

Hereinafter, the present invention will be described in detail. The embodiments introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. In addition, if there is no other definition in the technical and scientific terms used in the present invention, it has the meaning commonly understood by those of ordinary skill in the art to which this invention belongs, and the gist of the present invention in the following description Descriptions of known functions and configurations that may be unnecessarily obscure will be omitted.

In addition, unless otherwise specified in the specification, % means % by weight.

The term "{100} plane" used in the present invention means a plane in which the crystallographic {100} plane of the crystal grains constituting the electrical steel sheet is parallel to the plate plane of the electrical steel sheet. Here, the plate surface of the 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) is the y-axis.

{100} For the measurement of texture and average grain size (diameter), the surface strength for each orientation was calculated and analyzed using an orientation distribution function (ODF) using EBSD (Electron Backscatter Diffraction).

As used in the present invention, the term “face strength of {100} texture” refers to a relative strength based on Intensity 1 of a disordered tissue that does not have any texture. In addition, the maximum aggregate strength of {100} ({100} _max ) means the maximum strength among the texture strengths of the {100} texture shown in the azimuth distribution function image (ODF image, φ ₂ =45º degree section). .

Non-oriented electrical steel sheet according to an embodiment of the present invention by weight%, Si: more than 2.6% 4% or less, Al: more than 0.6% 2% or less, Nb: more than 0.001% 0.005% or less, Mn: less than 0.1% ( excluding 0%), S: less than 0.01% (excluding 0%), C: less than or equal to 0.004% (excluding 0%), N: less than or equal to 0.004% (excluding 0%), P: less than 0.01% (excluding 0%), V: less than 0.005% (excluding 0%), Mo: less than 0.003% (excluding 0%), Ti: less than 0.03% (excluding 0%), Sb: less than 0.015% (excluding 0%), Sn: less than 0.005% ( excluding 0%), Cu: 0.04% by weight or less (excluding 0%), Bi: less than 0.0005% (excluding 0%), As: less than 0.0005% (excluding 0%), Ga: less than 0.002% (excluding 0%), O: 0.005% or less (excluding 0%) and the remainder including Fe and other unavoidable impurities, but may be characterized by satisfying the following Relations 1, 2, 3 and 4.

[Relational Expression 1]

[Sb]+[Sn]+[P]<0.02 (excluding 0)

[Relational Expression 2]

[Bi]+[Ga] < 0.002 (excluding 0)

[Relational Expression 3]

3 ≤ {100} _max ≤ 10

[Relational Expression 4]

0 ≤ ({110} _max /{100} _max ) ≤ 1.5

(In Relations 1 and 2, [Sb], [Sn], [P], [Bi] and [Ga] represent the contents (% by weight) of Sb, Sn, P, Bi and Ga, respectively,

In Relations 3 and 4, {100} _max and {110} _max are the maximum sets of {100} or {110} textures in which the {100} or {110} orientation is parallel to the steel plate within 15° It represents the tissue strength, and the steel sheet surface means the xy surface when the rolling direction of the electrical steel sheet is the x-axis and the width direction is the y-axis.)

As such, the tensile strength is increased by maximizing the amount of Al added to maximize the solid solution strengthening effect per weight%, and the surface strength of the {100} texture excellent in magnetic properties is increased, but the average grain size is appropriately adjusted so as not to impair the tensile strength. It is possible to provide a non-oriented electrical steel sheet having improved tensile strength and magnetic properties by controlling the cold rolling process and heat treatment time to be short so that it can be adjusted.

More preferably, Relation 3 may satisfy 7 ≤ {100} _max ≤ 9, Relation 4 may satisfy 0 ≤ {110} _max /{100} _max ≤ 1.2, In this case, 3 ≤ {110} _max ≤ It could be 8. More preferably, Relation 3 may satisfy 7.5 ≤ {100} _max ≤ 9, Relation 4 may satisfy 0.5 ≤ {110} _max /{100} _max ≤ 1, where 4 ≤ {110} _max ≤ can be 6 In such a range, superior magnetic properties can be secured.

In addition, the average grain size of the non-oriented electrical steel sheet according to an embodiment of the present invention may be 70 to 350 μm, more preferably 70 to 200 μm, even more preferably 70 to 100 μm. While satisfying the above Relations 3 and 4, the average grain size satisfies the above range, so that more excellent magnetic flux density can be secured.

As a specific example, the non-oriented electrical steel sheet according to an example of the present invention may have a magnetic flux density (B ₅₀ ) in the rolling direction of 1.60 Tesla or more, more preferably 1.74 Tesla or more, and even more preferably 1.76 Tesla or more. . At this time, the upper limit of the magnetic flux density (B ₅₀ ) is not particularly limited, but may be, for example, 2.0 Tesla.

In addition, as mentioned above, as the average grain size increases, the tensile strength and fatigue strength of the electrical steel sheet decrease. . As a specific example, the non-oriented electrical steel sheet according to an embodiment of the present invention may have a tensile strength of 485 MPa or more in a rolling direction.

In addition, the non-oriented electrical steel sheet according to an example of the present invention may have an iron loss (W _15/50 ) in the rolling direction of 2.4 W/kg or less, more preferably 2.0 W/kg or less, and even more preferably 1.7 W/kg or less. kg or less. In this case, the lower limit of the iron loss (W _15/50 ) is not particularly limited, but may be, for example, 0.1 W/kg.

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

Si: greater than 2.6% by weight and less than or equal to 4% by weight

The Si is a major element added because it is a component that increases the specific resistance of steel and lowers eddy current loss during iron loss. If it is less than 2.6%, it is difficult to obtain low iron loss characteristics, and if it is added in excess of 4%, plate fracture occurs during cold rolling. In the invention, Si is limited to more than 2.6% and not more than 4%.

Al: greater than 0.6% by weight and less than or equal to 2% by weight

The Al is an alloying element that increases solid solution strength and increases specific resistance. In order to increase tensile strength and specific resistance, Al must be added in excess of 0.6%, and when added in excess of 2%, it is cold by increasing strength and forming a large amount of AlN precipitates. Since there is a risk of plate breakage during rolling, in the present invention, it is preferable to limit the addition amount of Al to more than 0.6% and not more than 2%.

Nb: greater than 0.001% by weight and less than or equal to 0.005% by weight

The Nb forms fine NbN precipitates to suppress the growth of crystal grains, and develops a texture of {111} plane unfavorable to magnetism. In addition, since Nb combines with C to make fine carbide, it is necessary to reduce Nb as much as possible in the slab. Since such Nb has a very large effect on the amount added, in the present invention, it is preferable to limit the amount of Nb added to more than 0.001% and 0.005% or less.

Mn: less than 0.1% by weight (excluding 0%)

As the amount of Mn added increases, the specific resistance increases and iron loss decreases. However, when a large amount of Mn is added, the maximum amount of Al that can be added decreases, so the tensile strength of the steel sheet decreases and the effect of increasing the specific resistance is small. rises In addition, in the present invention, it is preferable to limit the amount of Mn added to less than 0.1% in the present invention, because excessive MnS precipitates generated by the reaction of a large amount of Mn with S promotes {111} or {112} grain growth, which is unfavorable to magnetic properties. .

S: less than 0.01% by weight (excluding 0%)

Since S is an element that forms sulfides, such as MnS, which are harmful to magnetic properties, it is known that it is preferable to add S at a low level. However, when S is segregated on the surface of the steel, it has the effect of lowering the surface energy of the {100} plane. However, when S is added in an amount of 0.01% or more, {100} grain growth is suppressed due to excessive MnS precipitates, and S is segregated on the surface to lower the surface energy of the {111} plane to promote {111} grain growth. In the present invention, it is preferable to limit the addition amount of S to less than 0.01% (excluding 0%).

C: 0.004 wt% or less (excluding 0%)

When a large amount of C is added, it combines with Fe, Nb, Ti, etc. to form carbide, which is inferior to magnetism and increases iron loss by magnetic aging when used after processing from a final product into an electrical product. It is preferable to limit to the following.

N: 0.004 wt% or less (excluding 0%)

Since N is an element harmful to magnetism such as suppressing grain growth by forming a nitride with Fe, Nb, Al, Ti, etc., it is preferable to contain less, and in the present invention, it is preferable to limit the addition amount of N to 0.004% or less.

P: less than 0.01% by weight (excluding 0%)

The effect of P on {100} texture formation is insignificant, and when excessively added, it segregates at grain boundaries to weaken grain boundary strength, so it is preferable to limit the addition amount of P to less than 0.01% in the present invention.

V: less than 0.005 wt% (excluding 0%)

V has an effect of reducing iron loss by increasing specific resistance, but the effect is insignificant. Therefore, in the present invention, it is preferable to limit the amount of V added to less than 0.005%.

Mo: less than 0.003 wt% (excluding 0%)

The Mo has an effect of reducing iron loss by increasing specific resistance, but the effect is insignificant. Therefore, in the present invention, it is preferable to limit the addition amount of Mo to less than 0.003%.

Ti: 0.03% or less (excluding 0%)

The Ti can reduce iron loss by increasing specific resistance, but in the present invention, the amount of Ti added is limited to 0.03% or less because it can combine with N in steel to form precipitates that interfere with magnetic domain movement, thereby worsening iron loss. it is preferable

Sb: less than 0.015% (excluding 0%)

The Sb has an effect of reducing iron loss by improving the texture during annealing, but when added in excess, it may cause plate breakage during normal temperature rolling. In the present invention, it is preferable to limit the addition amount of Sb to less than 0.015%.

Sn: less than 0.005 wt% (excluding 0%)

The Sn has an effect of reducing iron loss by improving the texture during annealing, but when it is added in excess, it may cause plate breakage during normal temperature rolling. In the present invention, it is preferable to limit the amount of Sn to less than 0.005%.

Cu: 0.04 wt% or less (excluding 0%)

The Cu has an effect of reducing iron loss by improving the texture during annealing, but since it may deteriorate continuous castability at high temperature when excessively added, it is preferable to limit the addition amount of Cu to 0.04% or less in the present invention.

Bi: less than 0.0005% (excluding 0%)

The Bi has an effect of reducing iron loss by improving the texture during annealing, but when added in excess, it may cause plate breakage during normal temperature rolling. In the present invention, it is preferable to limit the amount of Bi to less than 0.0005%.

As: less than 0.0005% (excluding 0%)

The As has an effect of reducing iron loss by improving the texture during annealing, but when added in excess, it may cause plate breakage during normal temperature rolling.

Ga: less than 0.002% (excluding 0%)

The Ga has an effect of reducing iron loss by improving the texture during annealing, but when it is added in excess, it may cause plate breakage during normal temperature rolling.

In particular, as shown in Relations 1 and 2, [Sb]+[Sn]+[P], which is the sum of Sb, Sn, and P, is less than 0.02% (excluding 0%), and [Bi], which is the sum of Bi and Ga It is particularly preferable to control the +[Ga] to be less than 0.002% (excluding 0%) to prevent plate breakage during normal temperature rolling.

In addition, the non-oriented electrical steel sheet according to an embodiment of the present invention is the Si, Al, Nb, Mn, S, C, N, P, V, Mo, Ti, As, Sb, Sn, Cu, Bi, Ga, The total amount of the remaining element components other than O and Fe may be 1% or less. In detail, the remaining element components may be at least one selected from Pb, Zr, Se, Sr, In, Be, Mg, B, Co, Cr, Ni, W, and Ni.

At least one selected from Pb, Sb, Zr, Se, Sr, In, Be, Mg, B, Co, Cr, Ni, W and Ni: 1 wt% or less (excluding 0%)

Each of the above-mentioned elements may be added alone or in total in an amount of 1 wt% or less. The above elements are elements that exhibit a more improved effect on magnetism when added in a small amount, but when added in excess, they deteriorate continuous castability at high temperature or form austenite during final annealing to prevent {100} grain growth. It is preferable to manage it at 1 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 method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention is a) in weight %, Si: more than 2.6% and less than 4%, Al: more than 0.6% and less than or equal to 2%, Nb: more than 0.001% and less than or equal to 0.005%, Mn : Less than 0.1% (excluding 0%), S: Less than 0.01% (excluding 0%), C: Less than 0.004% (excluding 0%), N: Less than 0.004% (excluding 0%), P: Less than 0.01% ( excluding 0%), V: less than 0.005% (excluding 0%), Mo: less than 0.003% (excluding 0%), Ti: less than 0.03% (excluding 0%), Sb: less than 0.015% (excluding 0%), Sn : less than 0.005% (excluding 0%), Cu: less than 0.04 wt% (excluding 0%), Bi: less than 0.0005% (excluding 0%), As: less than 0.0005% (excluding 0%), Ga: less than 0.002% ( 0%), O: heating the slab containing 0.005% or less (excluding 0%) and the remainder of Fe and other unavoidable impurities to 1200° C. or less; b) preparing a hot-rolled sheet by hot-rolling the heated slab; c) cold-rolling the hot-rolled sheet to manufacture a cold-rolled sheet; and d) final annealing the cold-rolled sheet to produce a non-oriented electrical steel sheet, characterized in that it satisfies the following Relations 1, 2, 3 and 4.

[Relational Expression 1]

[Sb]+[Sn]+[P]<0.02 (excluding 0)

[Relational Expression 2]

[Bi]+[Ga] < 0.002 (excluding 0)

[Relational Expression 3]

3 ≤ {100} _max ≤ 10

[Relational Expression 4]

0 ≤ ({110} _max /{100} _max ) ≤ 1.5

(In Relations 1 and 2, [Sb], [Sn], [P], [Bi] and [Ga] represent the contents (% by weight) of Sb, Sn, P, Bi and Ga, respectively,

In Relations 3 and 4, {100} _max and {110} _max are the maximum sets of {100} or {110} textures in which the {100} or {110} orientation is parallel to the steel plate within 15° It represents the tissue strength, and the steel sheet surface means the xy surface when the rolling direction of the electrical steel sheet is the x-axis and the width direction is the y-axis.)

First, the slab is heated to 1200 ℃ or less. When it exceeds 1200 ℃, the precipitate is re-dissolved and can be finely re-precipitated after hot rolling, so it is preferable to heat to 1200 ℃ or less, specifically, it can be heated to 1100 to 1200 ℃.

Next, a hot-rolled sheet having a thickness of 1.8 to 3.0 mm may be manufactured by hot rolling the heated slab.

After the hot-rolled sheet is manufactured, a preliminary annealing step may be further performed before cold rolling is performed. The hot-rolled sheet pre-annealing may be performed at a temperature of 900 to 1150 °C. In the case of pre-annealing at less than 900 ° C, there is a risk of non-recrystallization of the internal structure of the hot-rolled sheet, and when it exceeds 1150 ° C, there is a risk of plate breakage during cold rolling due to the coarse grain size after pre-annealing, within 900 to 1150 ° C. Pre-annealing is preferably performed at a temperature of

Next, the hot-rolled sheet may be cold-rolled to manufacture a cold-rolled sheet having a thickness of 0.1 to 0.7 mm. The final rolling reduction during cold rolling may be 20 to 95%, but this may vary depending on the thickness of the hot-rolled sheet.

In addition, the cold rolling may be one-stage cold rolling without intermediate annealing, or two-stage cold rolling including intermediate annealing at 900 to 1150°C. In detail, when the intermediate annealing temperature in the two-stage cold rolling is lower than 900°C, recrystallization in the cold structure in the cold-rolled sheet is difficult, and when it exceeds 1150°C, the crystal grains grow excessively, and {100} grain growth during final annealing It is preferable to perform the intermediate annealing at a temperature within the range of 900 to 1150 °C for the intermediate annealing temperature during the two-stage cold rolling.

Next, the cold-rolled sheet may be final annealed to manufacture a non-oriented electrical steel sheet. The final annealing may be performed at 860 to 1150°C, and when the final annealing temperature is lower than 860°C, the growth of {100} grains is insufficient and the time required for recrystallization is long, making it difficult to realize in the process, exceeding 1150°C In , due to the decrease in strength due to excessive grain growth, the final annealing temperature of the cold-rolled sheet is within 850 to 1150°C.

In addition, the final annealing may be performed for 15 to 300 seconds, and when the final annealing time is less than 15 seconds, the magnetic properties are deteriorated due to insufficient grain growth, and when it exceeds 300 seconds, the productivity deteriorates and the grains are too coarse. As a result, the strength characteristics may be greatly reduced.

In addition, the final annealing of the cold-rolled sheet can be performed under a reducing or non-oxidizing gas atmosphere, and as such, the final annealing is performed in a reducing or non-oxidizing gas atmosphere in a short time using a steel sheet showing a ferrite structure in the pre-heat treatment temperature section. , it is possible to easily and inexpensively manufacture electrical steel sheets showing high tensile strength and high {100} texture strength. Specifically, the final annealing may be performed under a gas atmosphere containing hydrogen (H ₂ ) gas.

Hereinafter, a non-oriented electrical steel sheet and a manufacturing method thereof according to the present invention will be described in detail through examples. However, the following examples only illustrate the present invention, and the content of the present invention is not limited by the following examples.

Steel grade (wt%) S1 S2 S3 S4 Si 3.2 3.2 3.2 3.2 Al 0.02 0.02 0.8 1.2 Mn 0.1 0.8 0.02 0.02 Nb 0.002 0.002 0.002 0.002 S 0.001 0.001 0.001 0.002 C 0.001 0.002 0.001 0.002 N 0.002 0.002 0.001 0.001 P 0.002 0.002 0.001 0.002 V 0.001 0.001 0.002 0.001 Mo 0.001 0.003 0.001 0.002 Sn 0.002 0.001 0.001 0.002 Cu 0.002 0.001 0.001 0.002 Bi 0.0003 0.0003 0.0004 0.0003 Ga 0.0002 0.0003 0.0002 0.0002 O 0.001 0.001 0.001 0.001 As 0.0003 0.0004 0.0002 0.0002 Pb 0.0005 0.0006 0.0004 0.0003 Ti 0.003 0.002 0.001 0.001 Sb 0.001 0.001 0.002 0.001 Zr 0.002 0.001 0.002 0.001 Co 0.08 0.07 0.03 0.04 Cr 0.05 0.06 0.02 0.04 Ni 0.2 0.2 0.1 0.1 W 0.001 0.002 0.001 0.001 Se 0.0009 0.0005 0.0004 0.0002 Sr 0.0003 0.0002 0.0003 0.0003 In 0.0002 0.0002 0.0002 0.0003 Be 0.0004 0.0006 0.0002 0.0002 Mg 0.0002 0.0002 0.0002 0.0003 B 0.0003 0.0004 0.0002 0.0002 Other elements (total) ≤ 1.0 ≤ 1.0 ≤ 1.0 ≤ 1.0 Fe balance balance balance balance

[Examples 1 to 7 and Comparative Examples 1 to 4]

After dissolving the slab satisfying Table 1, it was heated to 1150° C. and hot rolled to a thickness of 2 mm. After pickling, the hot-rolled sheet was cold-rolled to a thickness of 0.2 mm, and then final annealed at the temperature and time conditions described in Table 2 below under an atmosphere of 75% by volume H ₂ + 25% by volume N ₂ .

For each specimen, the texture, average grain size, and maximum texture strength of the {100} texture were investigated using EBSD, and magnetic flux density (B ₅₀ ) and iron loss (W ₁₅ ) in the rolling direction using a magnetometer. _/50 ) was measured, and the tensile strength (Ts) results of the tensile test in the rolling direction using an Instron tensile tester are shown in Table 2 below.

In Comparative Examples 1 and 2 of the S1 steel type in Table 2, {100} _max was relatively high, but the amount of Mn and Al added was so small that the tensile strength was low. In addition, in Comparative Examples 3 and 4 for S2 steel type, the tensile strength was relatively increased compared to S1 steel type due to the addition of a large amount of Mn, but a large amount of MnS was precipitated to inhibit the growth of {100} grains to an extremely low {100} As the maximum aggregate strength of the texture was less than 2, the magnetic properties were inferior.

However, in Examples 1 to 7 for S3 and S4 steel grades in which the Mn addition amount was minimized and the Al addition amount having a large tensile strength increasing effect was maximized, the maximum aggregate strength ({100} _max ) of the {100} texture was 3 or more. and {110} _max /{100} _max showed 0 or more and 1.5 or less, indicating excellent magnetic properties, high tensile strength of 503 to 541 MPa, and average grain size of 75 or more and 339 μm or less.

Claims (10)

In wt%, Si: more than 2.6% and less than 4%, Al: more than 0.6% and less than 2%, Nb: more than 0.001% and less than or equal to 0.005%, Mn: less than 0.1% (excluding 0%), S: less than 0.01% (0%) excluding), C: 0.004% or less (excluding 0%), N: 0.004% or less (excluding 0%), P: less than 0.01% (excluding 0%), V: less than 0.005% (excluding 0%), Mo: Less than 0.003% (excluding 0%), Ti: less than 0.03% (excluding 0%), Sb: less than 0.015% (excluding 0%), Sn: less than 0.005% (excluding 0%), Cu: 0.04% by weight or less (0%) %), Bi: less than 0.0005% (excluding 0%), As: less than 0.0005% (excluding 0%), Ga: less than 0.002% (excluding 0%), O: less than 0.005% (excluding 0%) and the balance A non-oriented electrical steel sheet containing Fe and other unavoidable impurities, characterized in that it satisfies the following Relations 1, 2, 3 and 4,
The non-oriented electrical steel sheet has a magnetic flux density in the rolling direction (B ₅₀ ) of 1.60 Tesla or more, and an iron loss (W _15/50 ) in the rolling direction is 2.0 W/kg or less.
[Relational Expression 1]
[Sb]+[Sn]+[P]<0.02 (excluding 0)
[Relational Expression 2]
[Bi]+[Ga] < 0.002 (excluding 0)
[Relational Expression 3]
3 ≤ {100} _max ≤ 10
[Relational Expression 4]
0 ≤ ({110} _max /{100} _max ) ≤ 1.5
(In Relations 1 and 2, [Sb], [Sn], [P], [Bi] and [Ga] represent the contents (% by weight) of Sb, Sn, P, Bi and Ga, respectively,
In Relations 3 and 4, {100} _max and {110} _max are the maximum sets of {100} or {110} textures in which the {100} or {110} orientation is parallel to the steel plate within 15° It represents the tissue strength, and the steel sheet surface means the xy surface when the rolling direction of the electrical steel sheet is the x-axis and the width direction is the y-axis.) The method of claim 1,
The non-oriented electrical steel sheet has an average grain size of 70 to 350 μm, non-oriented electrical steel sheet. The method of claim 1,
The non-oriented electrical steel sheet has a tensile strength of 485 MPa or more in the rolling direction, non-oriented electrical steel sheet. delete delete The method of claim 1,
The non-oriented electrical steel sheet is of the remaining element components except for the Si, Al, Nb, Mn, S, C, N, P, V, Mo, Ti, As, Sb, Sn, Cu, Bi, Ga, O and Fe. A non-oriented electrical steel sheet with a total amount of 1% or less. a) in wt%, Si: more than 2.6% and less than 4%, Al: more than 0.6% and less than 2%, Nb: more than 0.001% and less than or equal to 0.005%, Mn: less than 0.1% (excluding 0%), S: less than 0.01% ( excluding 0%), C: 0.004% or less (excluding 0%), N: 0.004% or less (excluding 0%), P: less than 0.01% (excluding 0%), V: less than 0.005% (excluding 0%), Mo: less than 0.003% (excluding 0%), Ti: less than 0.03% (excluding 0%), Sb: less than 0.015% (excluding 0%), Sn: less than 0.005% (excluding 0%), Cu: 0.04% by weight or less (excluding 0%), Bi: less than 0.0005% (excluding 0%), As: less than 0.0005% (excluding 0%), Ga: less than 0.002% (excluding 0%), O: less than 0.005% (excluding 0%) and Heating the slab containing the remainder of Fe and other unavoidable impurities to 1200 ℃ or less;
b) preparing a hot-rolled sheet by hot-rolling the heated slab;
c) cold-rolling the hot-rolled sheet to manufacture a cold-rolled sheet; and
d) final annealing of the cold-rolled sheet to produce a non-oriented electrical steel sheet, characterized in that it satisfies the following Relations 1, 2, 3 and 4;
The final annealing is performed under a reducing or non-oxidizing atmosphere at 860 to 1150 ° C for 15 to 300 seconds,
The non-oriented electrical steel sheet has a magnetic flux density (B ₅₀ ) in the rolling direction of 1.60 Tesla or more, and the iron loss in the rolling direction (W _15/50 ) is 2.0 W/kg or less.
[Relational Expression 1]
[Sb]+[Sn]+[P]<0.02 (excluding 0)
[Relational Expression 2]
[Bi]+[Ga] < 0.002 (excluding 0)
[Relational Expression 3]
3 ≤ {100} _max ≤ 10
[Relational Expression 4]
0 ≤ ({110} _max /{100} _max ) ≤ 1.5
(In Relations 1 and 2, [Sb], [Sn], [P], [Bi] and [Ga] represent the contents (% by weight) of Sb, Sn, P, Bi and Ga, respectively,
In Relations 3 and 4, {100} _max and {110} _max are the maximum sets of {100} or {110} textures in which the {100} or {110} orientation is parallel to the steel plate within 15° It represents the tissue strength, and the steel sheet surface means the xy plane when the rolling direction of the electrical steel sheet is the x-axis and the width direction is the y-axis.) delete delete delete

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