KR20100071213A - Non-directional electrical steel sheets having low anisotropy and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A non-oriented electric steel sheet and the manufacturing method thereof in which anisotropy smalls are provided to reduce manufacturing method by increasing the magnetism. CONSTITUTION: A non-oriented electric steel sheet comprises Si 1.0~4.0 weight%, Mn 0.1~0.5 weight%, P 0.01~0.1 weight%, Al 0.1~1.0 weight%, C+S+Ti+N 0.004~0.011 weight%, Sn 0.01~0.10 weight%, the rest Fe and other inevitable impurities. A grain size of a steel sheet is smaller than (Si+Al)x45.

Description

Non-directional Electrical Steel Sheets Having Low Anisotropy and Manufacturing Method

The present invention relates to a method for manufacturing non-oriented electrical steel sheet used as an iron core of an electric device such as a motor, a transformer, and more particularly, to a non-oriented electrical steel sheet excellent in magnetic properties and a method for manufacturing the same.

 Non-oriented electrical steel is used as a core material for small transformers in rotating machines and motors such as motors and generators.The most important component in the design of electrical products is that the energy loss can be the largest in converting electrical energy into rotational energy. do. The iron core is used because it increases the size of the magnetic field when the electric field is applied to the magnetic field. If the iron loss of the non-oriented electrical steel sheet is low, the electrical loss can be reduced. Recently, attention has been focused on electric steel sheets for motors driving electric vehicles, since the most important material is non-oriented electrical steel sheets.

Iron loss may be lowered by lowering the thickness or by adding a large amount of alloying elements. However, iron loss may be made of clean steel with less impurity, or may be made of steel that can improve magnetism by adding additional elements. In the former case, the cost of the additional process is increased in the manufacturing process, and in the latter case, the cost of additional elements is increased.

The main magnetic properties required for non-oriented electrical steel sheets are low iron loss, high magnetic flux density, and small deviations in magnetic properties in the rolling direction, the rolling vertical direction and the circumferential direction. The non-oriented electrical steel sheet should have a small deviation from the rolling direction or other directions compared to the rolling direction, and, in the end, rotation is easy when the anisotropy is low. Among them, iron loss is considered to be an important factor because it is easy to rotate only when the anisotropy is low.

Factors affecting the magnetic properties include impurity components added and inevitably added, grain size of materials, and the like, and Japanese Patent No. 2700505 has a problem in that Sn, Ni, and Cu are added.

As for anisotropy, Japanese Laid-Open Patent Publication No. 2008-127659 demands a material having excellent anisotropy at an angle of 55 degrees relative to the rolling direction. Japanese Laid-Open Patent Publication 2006-045613 requires a material having excellent magnetic properties at 45 degrees relative to the rolling direction.

An object of the present invention is to solve the above problems of the prior art and to provide a non-oriented electrical steel sheet having low anisotropy and excellent magnetic properties.

The present invention for achieving the above object. By weight% Si: 1.0 ~ 4.0%, Mn: 0.1 ~ 0.5%, P: 0.01 ~ 0.1%, Al: 0.1 ~ 1.0%, (C + S + Ti + N): 0.004 ~ 0.011%, balance Fe and others It is composed of impurity added unavoidably, and the grain size (μm) of the steel sheet is smaller than (Si + Al) x 45, and the iron loss is composed of iron loss (L) in the rolling direction and iron loss (C) in the right direction in the rolling direction. Deviation satisfies (CL) x100 / (C + L) = 10%.

In addition, the steel sheet is characterized in that it further comprises Sn: 0.01 ~ 0.10%.

In the method for producing a non-oriented electrical steel sheet having a small anisotropy of the present invention, after reheating and hot rolling the slab of the composition, hot rolled sheet annealing or omitting, cold rolling, and then one stage annealing furnace and two stages The final annealing is characterized in that the annealing furnace divided into annealing furnace.

Here, the slab is characterized in that it further comprises Sn: 0.01 ~ 0.10%, the temperature of the first stage annealing furnace is 800 ~ 1050 ^o C, the temperature of the two stage annealing furnace is the temperature of 850 ~ 1,100 ^o C It characterized in that the range, between the first stage annealing path and the second stage annealing path is characterized in that the continuous connection is connected by a connecting passage.

The present invention provides a method of improving magnetic properties by reducing iron loss by appropriately combining the amount of impurity elements and the amount of (Si + Al) added to reduce anisotropy in non-oriented electrical steel sheets. Therefore, it is possible to improve the magnetism without excessively reducing the amount of impurity elements to provide a steel sheet that can reduce the cost.

The present invention is Si: 1.0 ~ 4.0%, Mn: 0.1 ~ 0.5%, P: 0.01 ~ 0.10%, Al: 0.1 ~ 1.0%, (C + S + Ti + N): 0.004 ~ 0.011%, remainder Formula (1): (Si + Al) x 45 = crystal grains Iron loss deviation equation (2) consisting of size (GS) and iron loss (L) in the rolling direction of the steel plate and iron loss (C) in the right direction in the rolling direction: (CL) x100 / (C + L) = 10% It provides a non-oriented electrical steel sheet with a small anisotropy to satisfy.

In addition, it provides a non-oriented electrical steel sheet having a small anisotropy further comprises Sn: 0.01 ~ 0.10% in the above components.

 In the non-oriented electrical steel sheet manufacturing process of hot rolling, hot-rolled sheet annealing or omitting, cold rolling and final annealing in the steel sheet composed of the above components and the balance Fe and other unavoidable impurities, annealing furnace when the final annealing 1 Single annealing furnace and two stage annealing furnace, the temperature of the first stage annealing furnace is 800 ~ 1050 ℃ and the temperature of the second stage annealing furnace is characterized in that the temperature range of 850 ~ 1100 ℃ small anisotropic small It provides a method for manufacturing electrical steel sheet.

It was investigated that a small grain size is required for the non-oriented electrical steel sheet to have a small deviation in the other direction from the rolling direction. However, the non-oriented electrical steel sheet also had a problem that the iron loss is increased when the grain is excessively small, especially hysteresis loss among the iron loss. In order to improve the average magnetic value, grains have to be grown, but in order to reduce the variation of magnetism in the rolling direction, it is required to make the grains small. However, when a large amount of alloying elements of Si and Al was added, grains were greatly grown. Also, grains were greatly grown even when the amounts of impurity elements C, S, Ti, and N were reduced. However, excessively large grains resulted in deviations of magnetism and deterioration of magnetism. In addition, Sn was added in order to adjust the grains by segregation in the grain boundary.

It was shown that the iron loss deviation can be reduced by reducing the amount of impurity elements (C + S + Ti + N) and by appropriately adjusting the amount and grain size of the alloying elements in the alloying elements.

In the constituents of the present invention, it was found that there is a certain relationship between the sum of Si and Al and the grain size (1) .Si and Al are irradiated as representative elements for growing grains in the component system of the present invention. appear. Although it is possible to grow crystal grains larger, it is preferable to use impurity elements to grow within the scope of the present invention and to reduce the deviation of magnetic properties. When the grain size was larger than the product of (Si + Al) times 45, the anisotropy increased.

(1): (Si + Al) x 45 = grain size of the steel sheet (unit: 탆)

In the present invention, the iron loss deviation formula (2) consisting of iron loss (L) in the rolling direction of the steel sheet and iron loss (C) in the direction perpendicular to the rolling direction was used. The rolling direction and the rolling direction and the vertical direction can easily measure the direction. The rolling direction is the best magnetic and the vertical direction of the rolling direction is the bad magnet.

(2): (C-L) x100 / (C + L) = 10%

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In order to reduce iron loss by appropriately reducing the amount of impurity element (C + S + Ti + N) and increasing the specific resistance among alloying elements to reduce the eddy current loss and the grain size, It was adjusted appropriately.

First, look at the reasons for limiting the components of the present invention.

(C + S + Ti + N): 0.004-0.011%,

C, S, Ti and N are impurity elements that can be added unavoidably. The four elements should be contained at least 0.011%. Even if it is excessively low, the magnetism is worsened because the deviation of the magnetism increases. If it is less than 0.004%, the grain size becomes excessively large and the magnetic deviation increases, and if it is added more than 0.0011%, the grain size becomes excessively small and the magnetism deteriorates. The upper limit for each element is as follows.

  C causes self-aging in the final product, and also forms carbides, which contain less than 0.004% as much as possible by increasing iron loss during use.

S should not exceed 0.004% by weight because it is advantageous to form MnS, a fine precipitate, to be managed as low as possible by increasing iron loss.

Since N forms fine and long AlN precipitates to suppress grain growth, the content of N is less. In the present invention, N is preferably limited to 0.004% by weight or less.

Ti is less than 0.001% to 0.005% in the present invention because fine precipitates of TiN and TiC are made to suppress grain growth. In addition, when more than this is added, too many fine precipitates are generated to deteriorate the texture and increase iron loss.

Si: 1.0-4.0 wt%

Since Si is a component that increases the specific resistance and lowers the eddy current loss during iron loss, Si is an important element that determines the magnetism by growing crystal grains in combination with Al. If it is added in excess of 4.0% by weight, cold rolling property is lowered and plate breaking occurs, so it is preferable to limit it to 1.0 to 4.0% by weight.

P: 0.01% to 0.1% by weight

The P is added to increase the specific resistance to lower the iron loss, but if P is excessively limited to 0.1 wt% or less due to poor cold rolling. However, the crystal grains are excessively increased to 0.01% or less and the magnetic deviation increases, so 0.01% or more is added.

Mn: 0.1-0.5 wt%

The Mn develops the texture of the texture, and is added since yesterday to the generation of fine precipitates, MnS, and when added to less than 0.01%, the texture becomes worse, and when 0.5% or more is added, the decrease in iron loss is small compared to the amount of addition and cold rolling. Harms the castle. Therefore, Mn is preferably added 0.1 to 0.5% by weight.

Al: 0.1-1.0 wt%

The Al is an effective ingredient to increase the specific resistance and lower the eddy current loss, and when added below 0.1%, AlN is a precipitate that inhibits grain growth, and when it is added in excess of 1.0% by weight, the magnetism is improved compared to the added amount. Since the degree of falls, it is preferable to limit to 1.0% by weight. Therefore, Al is added in 0.1 ~ 1.0%.

Sn: 0.01-0.1 wt%

The Sn is added to the grain boundary to suppress the growth of grains and improve the texture of the grains. If Sn is added at 0.01% or less, the Sn is not more than 0.01%.

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

The steel slab formed as described above is reheated to 1200 ° C. or lower under normal conditions, and then hot rolled. The hot rolling method is rough rolling and finishing rolling, finishing finishing of finishing rolling is finished on ferrite, and final loading rate is 40% or less for straightening of plate.

The hot rolled sheet prepared as described above is wound up at 680 ° C. or lower and cooled in air. Hot-rolled sheet annealing can be made into the range of 900-1100 degreeC.

The wound hot rolled sheet is cold rolled after annealing and pickling. Cold rolling is finally rolled to a thickness of 0.10mm to 0.70mm. If necessary, the first cold rolling may be followed by the second cold rolling after the intermediate annealing, and the final rolling rate may be in the range of 50 to 95%. The final cold rolled steel sheet is blunt two stages. The first stage annealing and the second stage annealing separate the annealing path, and the first stage annealing and the second stage annealing are performed. The first stage annealing temperature is equal to or lower than the second stage annealing temperature.

In the present invention, the temperature of the first stage annealing is 800 ~ 1050 ℃ and the temperature of the second stage annealing is set to a temperature range of 850 ~ 1100 ℃. The distinction between 1-stage annealing and 2-stage annealing is to reduce the magnetic deviation by securing stable cracking temperature in 2-stage annealing. Create a connecting passage between them so that they can be continuously annealed. If the temperature of the one-stage annealing is excessively high, the deviation of the magnetism in the rolling direction and the rolling vertical direction increases, so the temperature of the one-stage annealing is set to 800 to 1050 ° C. The temperature of the two-stage annealing is separated from the one-stage annealing in order to grow the grains and reduce the deviation of the magnetic, and anneal at 850 ~ 1100 ℃.

The annealing plate is shipped to the customer after the insulation coating treatment. The insulating coating may be treated with an organic, inorganic and organic-inorganic composite coating, and may be treated with other insulating coating. The customer can use the steel plate as it is after processing.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

The steel slab, as shown in Table 1 below, was heated at 1150 ° C., and finish rolling at hot rolling was performed at 880 ° C. The rolling reduction in the last stand during filamentous rolling of hot rolling was 15%, rolled to a thickness of 2.2 mm, and wound up at 620 ° C. The hot rolled steel sheet wound and cooled in air is annealed at 1000 ℃, pickled, cold rolled to 0.35mm thickness, and annealed, but the first stage annealing temperature and the second stage annealing temperature are 980 ℃ and 1020 ℃, respectively. Hold for 1 minute. The annealing plate was measured after the iron loss measurement and grains, the results are shown in Table 2.

Gang name C Si S P Mn Al N Ti Sn C + S + Ti + N Comparative Steel A 0.0035 2.73 0.0045 0.03 0.25 0.70 0.0025 0.0009 0.025 0.0114 Comparative Steel B 0.0015 2.71 0.0005 0.02 0.26 0.20 0.0009 0.0009 - 0.0038 Inventive Steel A 0.0015 2.70 0.0015 0.03 0.27 0.30 0.0012 0.0017 - 0.0059 Inventive Steel B 0.0030 2.72 0.0020 0.06 0.27 0.51 0.0011 0.0035 0.025 0.0076 Invention Steel C 0.0026 2.73 0.0010 0.04 0.25 0.70 0.0012 0.0030 0.03 0.0078 Inventive Steel D 0.0021 1.60 0.0025 0.09 0.45 0.84 0.0011 0.0016 0.05 0.0073 Inventive Steel E 0.0026 3.20 0.0020 0.07 0.29 0.71 0.0011 0.0016 0.025 0.0073 Comparative Steel C 0.0045 3.21 0.0035 0.02 0.29 0.71 0.0021 0.0023 0.025 0.0124

division Gang name (Si + Al) (Si + Al)
x 45 Grain size (㎛) Iron loss (W15 / 50) Iron loss
(CL) x100 / (C + L) Magnetic flux density
(B50) Comparative Material 1 Comparative Steel A 3.43 154 60 2.50 8 1.67 Comparative Material 2 Comparative Steel B 2.91 131 160 2.45 14 1.68 Invention 1 Inventive Steel A 3.00 135 110 2.10 6 1.69 Invention 2 Inventive Steel B 3.23 145 125 2.15 5 1.70 Invention 3 Invention Steel C 3.43 154 115 2.15 4 1.72 Invention 4 Inventive Steel D 2.44 110 75 2.32 4 1.70 Invention 5 Inventive Steel E 3.91 176 150 1.95 5 1.69 Comparative Material 3 Comparative Steel C 3.92 176 50 2.36 12 1.66

1) _Iron loss (W _15/50 ) is the loss (W / kg) when the magnetic flux density of 1.5 Tesla is induced at 50 Hz frequency.

2) The magnetic flux density (B50) is the strength of the magnetic field induced at 5,000 A / m

As shown in Table 2, the invention materials (1 to 5) manufactured using the inventive steels (A to E) satisfying the component range of the present invention under the manufacturing conditions of the present invention, the degree of iron loss while the iron loss is low It can be seen that the magnetic flux density is relatively high. Comparative Material 1 was found to have a large amount of impurities including S, so that the grains were excessively small and the magnetism was bad. Comparative material 2 indicates that excessive clean steel may result in excessive grain growth and large deviations. In Comparative Material 3, the amount of (C + S + N + Ti) was high, and among them, C was 0.0045%, indicating that the grains were small, indicating that the total magnetism was lowered and the magnetic deviation was also increased.

 Example 2

By weight, C: 0.0025%, Si: 3.1%, Mn: 0.15%, P: 0.015%, S: 0.0011%, Al: 0.60%, N: 0.0015%, Ti: 0.0015%, Sn: 0.025% The slab composed of other unavoidable impurities was reheated to 1120 ° C., and then hot rolling was performed at a finishing rolling temperature of 800 ° C. and a reduction ratio of 19% at hot rolling to produce a 2.0 mm thick hot rolled steel sheet. The hot rolled steel sheet was wound at 600 ° C. and then air cooled. The hot rolled sheet annealing was continuously annealed and pickled at 950 ° C. for 5 minutes, and cold rolled to a thickness of 0.20 mm. The cold rolled plate was annealed as shown in Table 3 and examined for magnetic measurements and grain size. C + S + Ti + N = 0.0066%, (Si + Al) = 3.70%, and (Si + Al) x45 = 167. Comparative material 4 was found to be caused by high iron loss and large deviation due to excessively higher one-stage annealing temperature than two-stage annealing temperature. Comparative material 5 was investigated due to the excessively low one-stage annealing temperature due to the presence of stress in the steel sheet and excessively fine grains.

division 1 stage annealing temperature (℃) 2-stage annealing temperature
(℃) Grain size (㎛) Iron loss (W10 / 400) Iron loss
(CL) x100 / (C + L) Magnetic flux density
(B50) Comparative Material 4 1050 1020 220 13.5 15 1.62 Comparative Material 5 750 1020 55 12.5 9 1.65 Invention 6 980 1020 95 10.7 6 1.68 Invention Material7 1020 1050 120 9.8 5 1.67

1) _Iron loss (W _10/400 ) is the loss (W / kg) when the magnetic flux density of 1.0 Tesla is induced at 400 Hz frequency.

2) The magnetic flux density (B50) is the strength of the magnetic field induced at 5,000 A / m

Claims (6)

By weight% Si: 1.0 ~ 4.0%, Mn: 0.1 ~ 0.5%, P: 0.01 ~ 0.1%, Al: 0.1 ~ 1.0%, (C + S + Ti + N): 0.004 ~ 0.011%, balance Fe and others It is composed of impurity added unavoidably, and the grain size of the steel sheet is smaller than (Si + Al) x 45, and the iron loss is composed of iron loss (L) in the rolling direction and iron loss (C) in the right direction in the rolling direction. The non-oriented electrical steel sheet having a small anisotropy, wherein the deviation satisfies (CL) x100 / (C + L) = 10%. The method of claim 1, The steel sheet is a non-oriented electrical steel sheet having a small anisotropy, characterized in that it further comprises Sn: 0.01 ~ 0.10%. The slab of the composition of claim 1 is reheated and hot rolled, and then hot-rolled sheet annealing is omitted or cold-rolled, followed by final annealing in an annealing furnace divided into a first stage annealing furnace and a second stage annealing furnace. Method for producing a non-oriented electrical steel sheet having a small anisotropy. The method of claim 3, The slab is a method for producing a small anisotropic non-oriented electrical steel sheet, characterized in that it further comprises Sn: 0.01 ~ 0.10%. The method according to claim 3 or 4, The temperature of the first stage annealing furnace is 800 ~ 1050 ℃, the temperature of the second stage annealing furnace is a manufacturing method of a small anisotropic non-oriented electrical steel sheet, characterized in that the temperature range of 850 ~ 1,100 ℃. The method of claim 5, The method of manufacturing a non-oriented electrical steel sheet having a small anisotropy, characterized in that connected between the first stage annealing path and the second stage annealing passage is continuous annealing.