KR20210080658A - Non-oriented electrical steel sheet and method for manufacturing the same - Google Patents

Abstract

A non-oriented electrical steel sheet according to an embodiment of the present invention includes 0.1 to 1.9 wt% of Si, 0.005 to 1.0 wt% of Mn, 0.005 to 0.6 wt% of Al, 0.0005 to 0.0035 wt% of Bi, and 0.0005 to 0.0045 wt% of As, and the balance includes Fe and unavoidable impurities. In the non-oriented electrical steel sheet of the present invention, Bi and As are added to minimize the influence of precipitates and to thereby have excellent magnetic density and iron loss.

Description

Non-oriented electrical steel sheet and its manufacturing method {NON-ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME}

One embodiment of the present invention relates to a non-oriented electrical steel sheet and a method for manufacturing the same. More specifically, an embodiment of the present invention relates to a non-oriented electrical steel sheet having excellent magnetic flux density and iron loss by adding Bi and As to minimize the influence of precipitates, and a method for manufacturing the same.

Electrical steel sheet is a product used as a material for transformers, motors, and electrical equipment, and is a functional product that places importance on electrical properties, unlike general carbon steel that values processability such as mechanical properties. Required electrical properties include low iron loss, high magnetic flux density, magnetic permeability and space factor.

Electrical steel sheet is further divided into grain-oriented electrical steel sheet and non-oriented electrical steel sheet. Grain-oriented electrical steel sheet is an electrical steel sheet with excellent magnetic properties in the rolling direction by forming a Goss texture ({110}<001> texture) throughout the steel sheet by using an abnormal grain growth phenomenon called secondary recrystallization. Non-oriented electrical steel sheet is an electrical steel sheet with uniform magnetic properties in all directions on the rolled sheet.

As a production process of non-oriented electrical steel sheet, after manufacturing a slab, an insulating coating layer is formed through hot rolling, cold rolling and final annealing.

As a production process of grain-oriented electrical steel sheet, after manufacturing a slab, an insulating coating layer is formed through hot rolling, preliminary annealing, cold rolling, decarburization annealing, and final annealing.

Double non-oriented electrical steel sheet has uniform magnetic properties in all directions, so it is generally used as a material for motor cores, iron cores of generators, electric motors, and small transformers. The typical magnetic properties of non-oriented electrical steel sheet are iron loss and magnetic flux density. The lower the iron loss of non-oriented electrical steel sheet, the lower the iron loss lost in the process of magnetizing the iron core, the higher the efficiency. A larger magnetic strength can be induced, and since a small current can be applied to obtain the same magnetic flux density, copper loss can be reduced and energy efficiency can be improved.

A method commonly used to increase the magnetic properties of the non-oriented electrical steel sheet is to add an alloying element such as Si. The specific resistance of the steel can be increased through the addition of such alloying elements. As the specific resistance increases, the eddy current loss decreases, thereby lowering the total iron loss. On the other hand, as the amount of Si added increases, the magnetic flux density becomes inferior and brittleness increases. When a certain amount or more is added, cold rolling becomes impossible, making commercial production impossible. In particular, as the thickness of the electrical steel sheet is made thinner, the iron loss can be reduced. Elements such as Al and Mn are added to further increase the specific resistance of the steel to produce the highest grade non-oriented electrical steel sheet with excellent magnetic properties.

However, as described above, as the amount of added elements increases to increase the specific resistance, the process cost increases due to problems such as a decrease in rollability and a decrease in continuous annealing productivity. There is also a steady demand for mid- to low-end non-oriented electrical steel sheets.

In the case of such a low-end non-oriented electrical steel sheet, despite the relatively low Si content, the iron loss is about 50% lower than that of a general cold-rolled steel sheet, so the price/performance ratio is excellent. These low- and mid-grade non-oriented electrical steel sheets have a greater influence of precipitates and grain size on iron loss than high-end materials. Therefore, in order to secure the characteristics of low-end non-oriented electrical steel sheet, a technique for controlling the formation of coarse precipitates and grain growth is required. However, stricter standards for impurity control cause an increase in cost, and thus the application is limited.

An embodiment of the present invention is to provide a non-oriented electrical steel sheet and a method for manufacturing the same. More specifically, in an embodiment of the present invention, Bi and As are added to provide a non-oriented electrical steel sheet having excellent magnetic flux density and iron loss by minimizing the influence of precipitates, and a method for manufacturing the same.

The non-oriented electrical steel sheet according to an embodiment of the present invention is, by weight, Si: 0.1 to 1.9%, Mn: 0.005 to 1.0%, Al: 0.005 to 0.6%, Bi: 0.0005 to 0.0035%, and As: 0.0005 to 0.0045 %, and the balance includes Fe and unavoidable impurities.

The non-oriented electrical steel sheet according to an embodiment of the present invention may further include at least one of P: 0.1 wt% or less, Sn: 0.08 wt% or less, and Sb: 0.08 wt% or less.

The non-oriented electrical steel sheet according to an embodiment of the present invention may further include one or more of C: 0.01 wt% or less, S: 0.01 wt% or less, N: 0.01 wt% or less, and Ti: 0.005 wt% or less .

The non-oriented electrical steel sheet according to an embodiment of the present invention may further include at least one of Cu, Ni, and Cr in an amount of 0.05 wt% or less, respectively.

The non-oriented electrical steel sheet according to an embodiment of the present invention may further include at least one of Zr, Mo, and V in an amount of 0.01 wt% or less, respectively.

The ratio of the number of precipitates having a particle diameter of 100 nm or less among the total precipitates of the steel sheet may be 3% or less.

The ratio of the number of precipitates having a particle diameter of 1 μm or more among all precipitates of the steel sheet may be 55% or more.

The ratio of the number of precipitates having a particle diameter of 2 μm or more among all precipitates of the steel sheet may be 25% or more.

The non-oriented electrical steel sheet according to an embodiment of the present invention may satisfy Equation 1 below.

[Equation 1]

[W15/50] ≤ 6.7 - 1.8 × [Si] ² + 0.4 × [t]

(In Equation 1, [W15/50] represents the iron loss (W15/50) value (W/kg), Si represents the Si content (wt%) in the steel sheet, and t represents the thickness (mm) of the steel sheet. )

The method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention is, by weight%, Si: 0.1 to 1.9%, Mn: 0.005 to 1.0%, Al: 0.005 to 0.6%, Bi: 0.0005 to 0.0035%, and As: Preparing a hot-rolled sheet by hot-rolling a slab containing 0.0005 to 0.0045%, and the remainder being Fe and unavoidable impurities; It includes the steps of manufacturing a cold-rolled sheet by cold-rolling the hot-rolled sheet and final annealing of the cold-rolled sheet.

After the step of manufacturing the hot-rolled sheet, the step of annealing the hot-rolled sheet may be further included.

The step of annealing the hot-rolled sheet includes a first annealing step of hot-rolled sheet annealing at a temperature of 850 to 1050° C. for 40 to 100 seconds and a second annealing step of hot-rolled sheet annealing at a temperature of 750 to 950° C. for 30 to 95 seconds. can do.

According to an embodiment of the present invention, it is possible to manufacture a medium-low grade non-oriented electrical steel sheet having relatively excellent magnetic properties by coarsening or suppressing precipitation and sufficiently growing the grain size.

Terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and/or sections. These terms are used only to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is for the purpose of referring to specific embodiments only, and is not intended to limit the invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising," as used herein, specifies a particular characteristic, region, integer, step, operation, element and/or component, and includes the presence or absence of another characteristic, region, integer, step, operation, element and/or component. It does not exclude additions.

When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part, or the other part may be involved in between. In contrast, when a part refers to being "directly above" another part, the other part is not interposed therebetween.

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

In an embodiment of the present invention, the meaning of further including the additional element means that the remaining iron (Fe) is included by replacing the additional amount of the additional element.

Although not defined otherwise, all terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Commonly used terms defined in the dictionary are additionally interpreted as having a meaning consistent with the related technical literature and the presently disclosed content, and unless defined, they are not interpreted in an ideal or very formal meaning.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

The non-oriented electrical steel sheet according to an embodiment of the present invention is, by weight, Si: 0.1 to 1.9%, Mn: 0.005 to 1.0%, Al: 0.005 to 0.6%, Bi: 0.0005 to 0.0035%, and As: 0.0005 to 0.0045 %, and the balance includes Fe and unavoidable impurities.

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

Si: 0.1 to 1.9 wt%

Silicon (Si, silicon) serves to lower the iron loss by increasing the specific resistance of the material, and if it is added too little, the effect of improving the iron loss may be insufficient. Therefore, it is advantageous to increase the content of Si, but it is advantageous to add it in an amount of 1.9% or less in low-end non-oriented electrical steel sheets where price competitiveness is important. Conversely, if too little silicon is added, magnetic properties may be rapidly deteriorated. Therefore, Si may be added in the above-mentioned range. More specifically, Si may be included in an amount of 0.2 to 1.5 wt%.

Mn: 0.005 to 1.000 wt%

Manganese (Mn) is an element that improves the iron loss by increasing the specific resistance of the material and plays a role in forming sulfides. If too little Mn is added, sulfide may be finely precipitated to deteriorate the magnetism. Conversely, if Mn is added too much, the magnetic flux density may decrease by promoting the formation of a {111} texture unfavorable to magnetism. Accordingly, Mn may be included in the above-described range. More specifically, it may include 0.100 to 1.000 wt% of Mn.

Al: 0.005 to 0.600 wt%

Aluminum (Al) serves to lower the iron loss by increasing the specific resistance of the material, and also improves the rollability or workability during cold rolling. If too little Al is added, there is no effect in reducing the high frequency iron loss, and the precipitation temperature of AlN is lowered, so that the nitride is formed finely, thereby reducing the magnetism. When Al is added too much, nitride is formed excessively, which deteriorates magnetism, and may cause problems in all processes such as steelmaking and continuous casting, thereby greatly reducing productivity. Accordingly, Al may be included in the above-described range. More specifically, it may contain 0.010 to 0.550 wt% of Al. More specifically, it may contain 0.030 to 0.500 wt% of Al.

Bi: 0.0005 to 0.0035 wt%

Bismuth (Bi) is a segregation element and segregates at grain boundaries, thereby reducing grain boundary strength and suppressing a phenomenon in which dislocations are adhered to grain boundaries. Through this, it is possible to contribute to controlling the precipitates by reducing the conditions for forming the precipitates. When Bi is included too little, it is difficult to expect the above-mentioned role. When Bi is included in an excessive amount, the magnetism may be deteriorated on the contrary. Accordingly, Bi may be included in the above-described range. More specifically, Bi may be included in an amount of 0.0010 to 0.0030 wt%.

As: 0.0005 to 0.0045 wt%

Arsenic (As, arsenic) is a segregation element and segregates at grain boundaries, thereby reducing grain boundary strength and suppressing the shape in which dislocations are fixed to grain boundaries. When too little As is included, it is difficult to expect the above-mentioned role. When As is included in an excessive amount, the magnetism may be deteriorated on the contrary. Accordingly, As may be included in the above-described range. More specifically, As may be included in an amount of 0.0010 to 0.0035 wt%.

The non-oriented electrical steel sheet according to an embodiment of the present invention may further include at least one of P: 0.1 wt% or less, Sn: 0.08 wt% or less, and Sb: 0.08 wt% or less. As described above, when an additional element is further included, it is included by replacing the remainder of Fe.

P 0.100 wt% or less

Phosphorus (P) not only serves to increase the specific resistance of the material, but also segregates at the grain boundary to improve the texture to increase the specific resistance and lower the iron loss, so it can be additionally added. However, if the amount of P added is too large, it may cause the formation of a texture unfavorable to magnetism, and thus have no effect of improving the texture, and excessive segregation at grain boundaries may reduce rollability and workability, thereby making production difficult. Therefore, P can be added in the above-mentioned range. More specifically, it may include 0.001 to 0.090% by weight of P. More specifically, it may include 0.005 to 0.085 wt% of P.

Sn: 0.0800 wt% or less

Tin (Sn) segregates at grain boundaries and surfaces to improve the texture of the material and inhibit surface oxidation, and thus may be additionally added to improve magnetism. When Sn is added too much, grain boundary segregation is severe, the surface quality is deteriorated, hardness is increased, and the cold-rolled sheet is fractured, thereby reducing the rollability. Therefore, Sn can be added in the above-mentioned range. More specifically, it may include 0.0001 to 0.0500 wt% of Sn. More specifically, it may include 0.0003 to 0.0350 wt% of Sn.

Sb: 0.0800 wt% or less

Antimony (Sb) segregates at grain boundaries and surfaces to improve the texture of the material and inhibit surface oxidation, so it may be additionally added to improve magnetism. When Sb is added too much, grain boundary segregation is severe, the surface quality is deteriorated, hardness is increased, and the cold-rolled sheet is broken, thereby reducing the rollability. Therefore, Sb can be added in the above-mentioned range. More specifically, it may include 0.0001 to 0.0600 wt% of Sb. More specifically, it may include 0.0002 to 0.0500 wt% of Sb.

The non-oriented electrical steel sheet according to an embodiment of the present invention may further include one or more of C: 0.01 wt% or less, S: 0.01 wt% or less, N: 0.01 wt% or less, and Ti: 0.005 wt% or less .

C: 0.0100 wt% or less

Carbon (C) combines with Ti, Nb, etc. to form carbide, which is inferior to magnetism, and when used after processing into electrical products in the final product, iron loss increases due to magnetic aging and reduces the efficiency of electric devices, so the upper limit is 0.0100 wt% can be done with More specifically, it may further include C in an amount of 0.0050 wt% or less. More specifically, it may further include 0.0001 to 0.0035 wt% of C.

S: 0.0100 wt% or less

Sulfur (S) is preferably added as low as possible because it forms fine sulfide inside the base material to suppress grain growth and weakens iron loss. When a large amount of S is included, it may combine with Mn and the like to form precipitates or cause high-temperature brittleness during hot rolling. Accordingly, S may be further included in an amount of 0.0100 wt % or less. Specifically, S may be further included in an amount of 0.0050 wt% or less. More specifically, it may further include 0.0001 to 0.0040 wt% of S.

N: 0.0100 wt% or less

Nitrogen (N) not only forms fine and long precipitates inside the base material by combining with Al, Ti, Nb, etc., but also worsens iron loss such as inhibiting grain growth by combining with other impurities to form fine nitrides. desirable. In an embodiment of the present invention, N may be further included in an amount of 0.0100 wt% or less. More specifically, it may further include N in an amount of 0.0050 wt % or less. More specifically, it may further include 0.0001 to 0.0030 wt% of N.

Ti: 0.0050 wt% or less

Titanium (Ti) is an element that has a very strong tendency to form precipitates in the steel, and forms fine carbides or nitrides inside the base material to inhibit grain growth. do. In an embodiment of the present invention, Ti may be further included in an amount of 0.0050 wt % or less. More specifically, Ti may be further included in an amount of 0.0030 wt% or less. More specifically, it may further include 0.0005 to 0.0020 wt% of Ti.

The non-oriented electrical steel sheet according to an embodiment of the present invention may further include at least one of Cu, Ni, and Cr in an amount of 0.05 wt% or less, respectively.

The non-oriented electrical steel sheet according to an embodiment of the present invention may further include at least one of Zr, Mo, and V in an amount of 0.01 wt% or less, respectively.

Cu, Ni and Cr, which are elements inevitably added in the steelmaking process, react with impurity elements to form fine sulfides, carbides, and nitrides, which have a detrimental effect on magnetism. Therefore, their content is limited to 0.05 wt% or less, respectively. In addition, since Zr, Mo, and V are strong carbonitride forming elements, it is preferable not to be added as much as possible, and each is contained in an amount of 0.01 wt% or less.

The balance contains Fe and unavoidable impurities. The unavoidable impurities are impurities that are mixed in the steelmaking step and the manufacturing process of the grain-oriented electrical steel sheet, which are widely known in the art, and thus a detailed description thereof will be omitted. In one embodiment of the present invention, the addition of elements other than the alloy components described above is not excluded, and may be included in various ways within the scope of not impairing the technical spirit of the present invention. When additional elements are included, they are included by replacing the remainder of Fe.

As described above, by appropriately controlling the amounts of Si, Mn, Al, Bi, and As added, it is possible to selectively form and control the precipitates.

Specifically, the ratio of the number of precipitates having a particle diameter of 100 nm or less among the total precipitates of the steel sheet may be 3% or less. Precipitates having a particle diameter of 100 nm or less impair the movement of the magnetic domain wall during the magnetization process, thereby making the magnetism inferior, so the ratio can be lowered. More specifically, the ratio of the number of precipitates having a particle diameter of 100 nm or less may be 2.0 to 3.0%. The particle size of the precipitate can be measured based on a plane parallel to the rolling plane (ND plane). The particle diameter of the precipitate is assumed to be an imaginary circle having the same area as the area of the precipitate, and means the diameter of the circle. The minimum particle size of the measurable precipitate may be 10 nm.

The ratio of the number of precipitates having a particle diameter of 1 μm or more among the total precipitates of the steel sheet may be 55% or more. As the ratio of the number of precipitates having a particle size of 1 μm or more increases, it means that a large amount of coarsened precipitates are formed, and deterioration of magnetism can be prevented due to the precipitates. More specifically, the ratio of the number of precipitates having a particle diameter of 1 μm or more may be 55.0 to 65.0%.

The ratio of the number of precipitates having a particle diameter of 2 μm or more among all precipitates of the steel sheet may be 25% or more. As the number ratio of the precipitates having a particle diameter of 2 μm or more increases, it means that a large amount of coarsened precipitates are formed, and deterioration of magnetism can be prevented due to the precipitates. More specifically, the ratio of the number of precipitates having a particle diameter of 2 μm or more may be 25.0 to 35.0%.

As described above, by appropriately controlling the amounts of Si, Mn, Al, Bi, and As added, the magnetic properties can be improved by selectively forming and controlling the precipitates to improve the texture.

Specifically, the iron loss (W _15/50 ) of the electrical steel sheet is 6.30 W/Kg or less, and the magnetic flux density (B ₅₀ ) may be 1.72T or more. The iron loss (W15/50) is the iron loss when a magnetic flux density of 1.5T is induced at a frequency of 50Hz. The magnetic flux density (B ₅₀ ) is the magnetic flux density induced in a magnetic field of 5000 A/m. More specifically, the iron loss (W _15/50 ) of the electrical steel sheet is 3.00 to 6.30 W/Kg, and the magnetic flux density (B ₅₀ ) may be 1.72 to 1.80T. In this case, the magnetic measurement standard may be 0.50 mm thick.

An embodiment of the present invention is a low-end non-oriented electrical steel sheet containing a small amount of Si, it is difficult to directly compare the magnetic properties of the high-grade non-oriented electrical steel sheet containing a large amount of Si.

Therefore, the iron loss can be evaluated by reflecting the Si content and the thickness of the steel sheet as shown in Equation 1 below.

[Equation 1]

[W15/50] ≤ 6.7 - 1.8 × [Si] ² + 0.4 × [t]

(In Equation 1, [W15/50] represents the iron loss (W15/50) value (W/kg), Si represents the Si content (wt%) in the steel sheet, and t represents the thickness (mm) of the steel sheet. )

A method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention comprises the steps of: manufacturing a hot-rolled sheet by hot rolling a slab; It includes the steps of manufacturing a cold-rolled sheet by cold-rolling the hot-rolled sheet and final annealing of the cold-rolled sheet.

Since the alloy composition of the slab has been described in the alloy composition of the non-oriented electrical steel sheet, the overlapping description will be omitted. Since the alloy composition is not substantially changed in the manufacturing process of the non-oriented electrical steel sheet, the alloy composition of the non-oriented electrical steel sheet and the slab is substantially the same.

Specifically, the slab is, by weight, Si: 0.1 to 1.9%, Mn: 0.005 to 1.0%, Al: 0.005 to 0.6%, Bi: 0.0005 to 0.0035% and As: 0.0005 to 0.0045%, the balance being Fe and inevitable It may contain impurities.

Since the other additional elements have been described in the alloy composition of the non-oriented electrical steel sheet, the overlapping description will be omitted.

The slab can be heated before hot rolling. The heating temperature of the slab is not limited, but the slab may be heated in the range of 1120 to 1250° C. for 0.1 to 1 hour. If the heating temperature of the slab is too high, precipitates such as AlN, MnS, etc. present in the slab are re-dissolved and then finely precipitated during hot rolling and annealing to suppress grain growth and reduce magnetism. More specifically, the slab may be heated in the range of 1150 to 1200° C. for 0.5 to 1 hour.

Next, the slab is hot-rolled to manufacture a hot-rolled sheet. The thickness of the hot-rolled sheet may be 2.0 to 3.0 mm. The finish rolling temperature in the step of manufacturing the hot-rolled sheet may be 800 to 1000 ℃. The hot-rolled sheet may be wound at a temperature of 700° C. or less.

After the step of manufacturing the hot-rolled sheet, the step of annealing the hot-rolled sheet may be further included.

At this time, the step of annealing the hot-rolled sheet is a first annealing step of the hot-rolled sheet annealing at a temperature of 850 to 1050 ℃ for 40 to 100 seconds, and annealing the second hot-rolled sheet for 30 to 95 seconds at a temperature of 750 to 950 ℃ may include steps. Hot-rolled sheet annealing requires a process of partial solutionization of precipitates at high temperature and a process of re-precipitating precipitates to be re-precipitated in the process of re-precipitating the precipitates that have been partially solutionized at high temperatures, and heat treatment at low temperature to coarsen the precipitates. The hot-rolled sheet annealing can be performed by dividing it into two steps.

The hot-rolled sheet annealing is performed in order to increase the orientation favorable to magnetism, if necessary, and may be omitted. The annealed hot-rolled sheet can be pickled.

Next, the hot-rolled sheet is cold-rolled to manufacture a cold-rolled sheet. Cold rolling is final rolling to a thickness of 0.35mm to 0.65mm. If necessary, secondary cold rolling may be performed after primary cold rolling and intermediate annealing, and the final rolling reduction may be in the range of 50 to 95%.

Next, the cold-rolled sheet is final annealed. In the process of annealing the cold-rolled sheet, the annealing temperature is not particularly limited as long as it is a temperature typically applied to the non-oriented electrical steel sheet. Since the iron loss of the non-oriented electrical steel sheet is closely related to the grain size, it can be annealed at 760 to 1000°C for 10 to 110 seconds. If the temperature is too low, the hysteresis loss increases because the crystal grains are too fine, and if the temperature is too high, the crystal grains are too coarse and the eddy loss increases, which may result in inferior iron loss. More specifically, it may be annealed for 30 to 80 seconds at a temperature of 780 to 980 ℃.

After final annealing, the steel sheet may have an average grain diameter of 10 to 70 μm, and all (99% or more) of the structure processed by cold rolling may be recrystallized.

After final annealing, an insulating film may be formed. The insulating film may be treated with an organic, inorganic and organic/inorganic composite film, and may be treated with other insulating film materials.

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

Example

A slab containing the alloy components and the remainder Fe and unavoidable impurities summarized in Tables 1 and 2 was prepared. The slab was heated at 1150°C, hot rolled and wound at 650°C. The wound and cooled hot-rolled steel sheet was annealed and pickled at the temperature shown in Table 2 below, then cold-rolled to the thickness shown in Table 2, and finally cold-rolled sheet annealing was performed. At this time, the annealing temperature is summarized in Table 2.

The prepared final annealed plate was formed as an Epstein test piece with a length of 305 mm and a width of 30 mm for magnetic measurement from the L direction (rolling direction) and C direction (rolling vertical direction), and the iron loss (W _15/50 ) and magnetic flux density (B ₅₀ ) was measured and the results are shown in Table 3 below.

In addition, in order to measure the size distribution of the precipitates, a 0.5mm x 0.5mm area was measured using Auto SEM. Based on the measured precipitate information, fractions of precipitates of 100 nm or less, 1 μm or more, and 2 μm or more were obtained.

The iron loss (W _15/50 ) is the average loss (W/kg) in the rolling direction and the vertical direction in the rolling direction when a magnetic flux density of 1.5 Tesla is induced at a frequency of 50 Hz.

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

Example Si Mn Al P C S N Ti Comparative Goods 1 0.38 0.03 0.012 0.092 0.0021 0.0038 0.0007 0.0015 Comparative Goods 2 1.22 0.21 0.054 0.029 0.0013 0.0025 0.0011 0.0008 Comparative Goods 3 0.75 0.19 0.018 0.085 0.0042 0.0013 0.0021 0.0005 Comparative Goods 4 1.38 0.27 0.410 0.066 0.0007 0.0032 0.0009 0.0009 invention material 1 0.65 0.24 0.440 0.049 0.0022 0.0017 0.0007 0.0018 invention material 2 0.55 0.89 0.080 0.027 0.0031 0.0009 0.0005 0.0005 invention material 3 0.24 0.47 0.030 0.085 0.0047 0.0008 0.0014 0.0017 Invention 4 0.17 0.07 0.470 0.058 0.0016 0.0005 0.0009 0.0009 invention 5 1.00 0.51 0.210 0.009 0.0031 0.0031 0.0016 0.0019 invention 6 0.54 0.09 0.430 0.005 0.0026 0.0006 0.0027 0.0006 invention 7 1.31 0.54 0.390 0.013 0.0012 0.0017 0.0021 0.0011 invention 8 0.71 0.31 0.210 0.027 0.0034 0.0026 0.0008 0.0007 invention 9 0.98 0.91 0.050 0.038 0.0007 0.0038 0.0005 0.0006 invention 10 0.59 0.45 0.040 0.072 0.002 0.0008 0.0006 0.0016 Invention 11 1.16 0.32 0.070 0.006 0.001 0.0027 0.0018 0.0008

Example
Sn
Sb
Bi
As Hot-rolled sheet annealing conditions
1st - 2nd thickness
(μm) Final annealing temperature
(℃) final annealing time
(s) Comparative Goods 1 0.0023 0.0015 0.0003 0.0005 - 0.35 780 45 Comparative Goods 2 0.0081 0.0005 0.0040 0.0045 1000 - 850 0.50 850 45 Comparative Goods 3 0.0005 0.0003 0.0033 0.0003 - 0.50 820 45 Comparative Goods 4 0.0351 0.0071 0.0018 0.0048 1000 - 830 0.65 910 50 invention material 1 0.0077 0.0011 0.0035 0.0043 - 0.35 830 45 invention material 2 0.0069 0.0049 0.0028 0.0029 - 0.50 870 30 invention material 3 0.0073 0.0065 0.0005 0.0005 - 0.50 800 45 Invention 4 0.0131 0.0002 0.0013 0.0027 - 0.50 820 40 invention 5 0.0268 0.0008 0.0016 0.0035 1000 - 900 0.50 830 45 invention 6 0.0095 0.0012 0.0024 0.0017 - 0.50 780 60 invention 7 0.0004 0.0007 0.0013 0.0006 1000 - 900 0.50 920 70 invention 8 0.0018 0.0312 0.0029 0.0019 980 - 850 0.50 950 55 invention 9 0.0015 0.0411 0.0011 0.0020 980 - 850 0.50 870 50 invention 10 0.0011 0.0023 0.0008 0.0023 - 0.65 880 45 Invention 11 0.0310 0.0165 0.0012 0.0021 980 - 850 0.65 830 60

Example Precipitate fraction below 100 nm
(%) Precipitate fraction over 1um
(%) Precipitate fraction over 2um
(%) iron loss
(W15/50,
W/kg) Equation 1 magnetic flux density
(B50, T) Comparative Goods 1 4.2 56.1 24.8 6.78 X 1.74 Comparative Goods 2 5.0 51.7 19.2 4.27 X 1.72 Comparative Goods 3 3.8 45.8 8.1 6.10 X 1.73 Comparative Goods 4 7.1 54.3 12.2 3.65 X 1.71 invention material 1 2.6 55.7 25.1 4.78 O 1.73 invention material 2 2.1 56.8 26.6 5.24 O 1.73 invention material 3 1.8 57.0 25.7 6.22 O 1.76 Invention 4 2.9 59.4 27.2 6.18 O 1.74 invention 5 2.2 62.2 32.3 4.38 O 1.73 invention 6 1.4 55.2 27.5 6.04 O 1.75 invention 7 2.7 56.5 25 3.60 O 1.72 invention 8 3.0 55.9 26.4 4.27 O 1.73 invention 9 2.4 61.2 31.3 4.73 O 1.74 invention 10 2.3 59.8 26.6 6.05 O 1.74 Invention 11 2.6 64.4 28.9 4.32 O 1.73

As shown in Tables 1 to 3, in Inventive Materials 1 to 11, in which Si, Al, Mn, Bi, and As satisfies each component addition range, the precipitate properties were improved, iron loss W _15/50 and magnetic flux density were improved. B _{50 was} also very good.

On the other hand, Comparative Example 1 contains too little Bi, so it can be confirmed that a large amount of fine precipitates are not generated, and the magnetism is poor.

Comparative Example 2 includes an excessive amount of Bi, so it can be confirmed that a large amount of fine precipitates are not generated, and the magnetism is poor.

Comparative Example 3 includes too little As, it can be confirmed that a large amount of fine precipitates are not generated, and the magnetism is poor.

Comparative Example 4 includes an excessive amount of As, it can be confirmed that a large amount of fine precipitates are not generated, and the magnetism is poor.

The present invention is not limited to the embodiments, but may be manufactured in various different forms, and those of ordinary skill in the art to which the present invention pertains may develop other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that this may be practiced. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (12)

By weight, Si: 0.1 to 1.9%, Mn: 0.005 to 1.0%, Al: 0.005 to 0.6%, Bi: 0.0005 to 0.0035% and As: 0.0005 to 0.0045%, the balance comprising Fe and unavoidable impurities Non-oriented electrical steel sheet. According to claim 1,
P: 0.1 wt% or less, Sn: 0.08 wt% or less, and Sb: Non-oriented electrical steel sheet further comprising at least one of 0.08 wt% or less. According to claim 1,
C: 0.01 wt% or less, S: 0.01 wt% or less, N: 0.01 wt% or less, and Ti: Non-oriented electrical steel sheet further comprising at least one of 0.005 wt% or less. According to claim 1,
A non-oriented electrical steel sheet further comprising at least one of Cu, Ni and Cr in an amount of 0.05 wt% or less, respectively. According to claim 1,
A non-oriented electrical steel sheet further comprising at least one of Zr, Mo, and V in an amount of 0.01 wt% or less, respectively. According to claim 1,
A non-oriented electrical steel sheet in which the ratio of the number of precipitates having a particle diameter of 100 nm or less among the total precipitates of the steel sheet is 3% or less. According to claim 1,
Non-oriented electrical steel sheet in which the ratio of the number of precipitates having a particle diameter of 1 μm or more among the total precipitates of the steel sheet is 55% or more. According to claim 1,
A non-oriented electrical steel sheet in which the ratio of the number of precipitates having a particle diameter of 2 μm or more among the total precipitates of the steel sheet is 25% or more. According to claim 1,
A non-oriented electrical steel sheet satisfying Equation 1 below.
[Equation 1]
[W15/50] ≤ 6.7 - 1.8 × [Si] ² + 0.4 × [t]
(In Equation 1, [W15/50] represents the iron loss (W15/50) value (W/kg), Si represents the Si content (wt%) in the steel sheet, and t represents the thickness (mm) of the steel sheet. ) By weight, Si: 0.1 to 1.9%, Mn: 0.005 to 1.0%, Al: 0.005 to 0.6%, Bi: 0.0005 to 0.0035% and As: 0.0005 to 0.0045%, the balance comprising Fe and unavoidable impurities manufacturing a hot-rolled sheet by hot-rolling the slab;
manufacturing a cold-rolled sheet by cold-rolling the hot-rolled sheet; and
A method of manufacturing a non-oriented electrical steel sheet comprising the step of final annealing the cold-rolled sheet. 11. The method of claim 10,
After the step of manufacturing the hot-rolled sheet, the method of manufacturing a non-oriented electrical steel sheet further comprising the step of annealing the hot-rolled sheet. 12. The method of claim 11,
The step of annealing the hot-rolled sheet includes a first annealing step of hot-rolled sheet annealing at a temperature of 850 to 1050° C. for 40 to 100 seconds and a second annealing step of hot-rolled sheet annealing at a temperature of 750 to 950° C. for 30 to 95 seconds A method of manufacturing a non-oriented electrical steel sheet comprising a.