KR930011406B1 - Method and product of manufacturing silicon steel sheet having improved magnetic flux density - Google Patents

Abstract

The steel sheet having superior magnetic properties comprises (in wt.) up to 0.02 % C, up to 0.008 % N, 1.0-3.5 % Si, up to 0.7 % Al, up to 1.0 % Mn, 0.05-1.0 % Ni, up to 0.10 % P, 0.02-0.50 % Cu, up to 0.01 % S, and 0.02-0.2 % Sn + Sb with the balance Fe. A steel slab is hot-rolled to give sheet which is pickled and cold- rolled with a one-stage or double cold-rolling method from which cold-rolled sheet is high-temp. annealed or annealed with stress- relieving. The sheets are used for the core materials of electrical equipment for example motors, generators, small transformers, etc., and have low iron loss and high magnetic flux density and permeability.

Description

Non-oriented electrical steel sheet having excellent magnetic properties and manufacturing method thereof

The present invention relates to a non-oriented electrical steel sheet used in the iron core of electric motors, such as various motors, small transformers, and a manufacturing method thereof, and more particularly, to a non-oriented electrical steel sheet having a low iron loss, high magnetic flux density and permeability, and a manufacturing method thereof. It is about.

In general, non-oriented electrical steel sheet is divided into magnetic properties based on Si content, so it is a low grade material when the Si content is 1.0% or less, a medium grade material when the Si content is 1.0 to 2.0%, and a high grade material when the Si content is 2.0% or more. Phase is divided.

This division is because the iron loss is lowered as much Si is added, but the magnetic flux density or permeability is rather reduced as the Si content is increased.

Therefore, efforts have been made to improve all of these magnetic properties in non-oriented electrical steel sheets.

The method of manufacturing the non-oriented electrical steel sheet is classified into a fully-process and a semi-process. The pulley process is a process in which hot rolled plates are pickled, cold rolled, and then annealed. The semi-process is a process where demand is processed after pickling hot rolled plates, cold rolling, and intermediate annealing, usually with a rolling pass of 15% or less.

In the case of the pulley process, there is a two-stage cold rolling method in which the first cold rolling during cold rolling, the intermediate annealing, and the second cold rolling are performed. However, the pulley process is also classified as a pulley process.

Conventional methods for producing grain-oriented electrical steel sheet are known to lower the Si or Al to increase the iron loss but increase the permeability. This method has limitations in use, and also increases the magnetic flux density and the permeability by increasing the Si and Al. However, there is a known method that is intended to lower the iron loss, this method has a problem in the efficiency of the electric machine.

In addition, Japanese Laid-Open Patent Publication No. 63-317627 discloses 0.2-1.0 wt% Si-containing steel containing 1.0-1.5 wt% of Mn, and at least one selected from the group consisting of Sn, Sb, Ni, and Cu. A non-oriented electrical steel sheet manufactured by semi-process by adding a paper phase and a manufacturing method thereof have been presented. Since the increase in cost and hot rolling is performed on austenite due to excessive addition of Mn, the problem of low magnetic flux density in the characteristics of the magnet is eliminated. have.

An object of the present invention is to provide an excellent non-oriented electrical steel sheet having low magnetic loss and high magnetic flux density and high magnetic permeability by a pulley process for appropriately selecting the component system of the non-oriented electrical steel sheet.

Hereinafter, the present invention will be described.

The present invention by weight, C: 0.02% or less, Si: 1.0-3.5%, Mn: 1.0% or less, P: 0.10% or less, S: 0.01% or less, N: 0.008% or less, Al: 0.7% or less, Ni: 0.05 to 1.0%, Cu: 0.02 to 0.5%, one or two of Sn and Sb: 0.02 to 0.2%, and a non-oriented electrical steel sheet having excellent magnetic properties composed of residual Fe and other unavoidable impurities. In addition, the present invention is a weight%, C: 0.02% or less, Si: 1.0 to 3.5%, Mn: 1.0% or less, P: 0.10% or less, S: 0.01% or less, N: 0.008% or less, Al: 0.7% Hereafter, Ni: 0.05 to 1.0%, Cu: 0.02 to 0.05%, one or two of Sn and Sb: 0.02 to 0.2%, hot rolled steel slab composed of balance Fe and other unavoidable impurities Annealing, pickling, 1st stage cold rolling or 1st cold rolling, after intermediate annealing, 2nd stage cold rolling after secondary cold rolling, and high temperature annealing and stress removal annealing of cold rolled plate Room to manufacture oriented electrical steel sheet Relate to.

Normally, when the segregation element of the grain boundary such as Sn or Sb coexists in the hot processing of the steel to which Cu is added, the melting point of the thickened and precipitated Cu is lowered, which may increase the susceptibility of surface cracking. Since Sn or Sb lowers the melting temperature of Cu, which is particularly invasive to grain boundaries of steel, it is necessary to make the amount of Cu and Sn or Sb less than the proper amount. The present inventors found that iron loss, magnetic flux density, and permeability are simultaneously improved when Sn or Sb, Ni, and Cu are added together than when adding elements one by one. These elements are added in one or two or more kinds because they control the grain shape and develop a good texture for magnetism such as (110) and (200), but Si is 1.0-3.5% as in the present invention, Mn In the non-oriented electrical steel sheet added at 1.0% or less, it was observed that grains grew particularly well by adding these elements simultaneously. In the manufacturing method as in the present invention, since the addition of components other than Fe as possible is a method of increasing the permeability, the components other than Si are added at 1.0% or less.

Hereinafter, the reason for numerical limitation about the component system of this invention is demonstrated.

The C may improve the texture, but when excessively remaining in the final product inhibits magnetism, the content is preferably limited to 0.02% or less, and decarburized so that C is 0.008% or less in the final product. It may be.

The Si is a basic component showing the product characteristics of the non-oriented electrical steel sheet to increase the specific resistance serves to lower the iron loss, if the content is less than 1.0%, the iron loss is increased, if more than 3.5% cold rolling property is bad Since the content of Si is preferably limited to 1.0 to 3.5%.

The Mn has the effect of lowering the iron loss by increasing the specific resistance, but in combination with S to MnS deteriorates the magnetism, there is a problem to manage S, and also because there is a problem that can not increase the reheating temperature to more than 1200 ℃ The content of Mn is preferably limited to 1.0% or less.

The P has an effect of lowering the iron loss by increasing the specific resistance and improving the magnetism by well developing the texture of the (200) and (100) surfaces which are favorable for magnetism, but the cold rolling property of the steel having a Si content of 1.0% or more In consideration, it is preferable to limit it to 0.1% or less.

It is advantageous for magnetism that S is not added as much as possible as an unnecessary impurity, but in the present invention, up to 0.01% does not significantly affect the magnetic properties.

The Al is added to improve the iron loss by increasing the specific resistance, but since the price is expensive, it is preferable to add up to 0.7% in consideration of the degree of magnetic improvement.

Since N is an impurity, it is advantageous to add as little as possible, and up to 0.008% can be tolerated.

When Ni is added alone, the effect is small, and Sn or So and Cu are added in combination, but the amount of addition is preferably limited to 0.5 ~ 1.0%, for less than 0.05%, the degree of magnetic enhancement is less. This is because the magnetic enhancement degree is less than the addition amount at 1.0% or more.

The Cu decreases iron loss by increasing the resistivity, which increases the corrosion resistance, which increases the life of electrical appliances, and develops the texture that is favorable for magnetism, but can ensure the cracking of the surface only during hot rolling, so the Cu content is 0.02. It is preferable to limit to 0.5%.

When Sn and Sb are added alone or in combination, Cu may be added up to 0.5% when the amount is less than 0.2%, but when the amount is more than 0.2%, the hot rolled plate is difficult to control the surface shape. It can be a cause of fatality.

Su or Sb can be added in one kind or two kinds, and these elements are segregated at grain boundaries, and the effect is less when the addition amount is less than 0.02%, and cold rolling is difficult when the amount is more than 0.2%. It is preferable to limit the amount of Sb or Sn alone or in combination to 0.02 to 0.2%.

Hereinafter, the method of manufacturing the non-oriented electrical steel sheet of the present invention will be described in detail.

Steel manufactured in the steelmaking process is charged into a hot rolled material furnace in the form of slabs and wound up at a temperature of 600 ° C. or higher after hot rolling. At this time, the reheating temperature of the slab can be heated to 1250 ° C. In order to grow a grain, it is preferable to set it as the range of 600-800 degreeC.

Hot-rolled sheet as described above is continuously annealed for 10 seconds to 20 minutes in the temperature range of 700-1100 ℃, when the continuous annealing time is less than 10 seconds, the crystal grains do not grow, the magnetism is poor, more than 20 minutes In this case, since equipment is subject to limitation, the continuous annealing time of the hot rolled sheet is preferably limited to 10 seconds to 20 minutes.

On the other hand, instead of continuously annealing the hot-rolled hot rolled plate as described above, the annealing may be performed, but when performing annealing, it is preferable to perform for 30 minutes-10 hours in the temperature range of 600-1000 ℃, the reason This is because when the annealing time is 30 minutes or less, the effect of the annealing is less, and when the annealing time is 10 hours or more, only the productivity without a large inclination is lost.

As described above, the continuous annealing or annealing hot rolled plate is pickled, subjected to two stages cold rolling followed by one stage cold rolling or the first cold rolling, and the second cold rolling after the intermediate annealing, followed by high temperature annealing.

The pulley process is a method in which the required cost is processed after the high temperature annealing of the cold rolled plate after the first stage cold rolling or the two stage cold rolling, as described above. The demand for the growth of stress-based grains after rolling at a light reduction rate is different from that of the semi-process which undergoes heat treatment.

The high temperature annealing is performed by continuous annealing for 10 minutes or less in the temperature range of 700-1100 ° C., and is preferably performed in an atmosphere of 100% nitrogen gas or a mixed gas of nitrogen and hydrogen and other reducing gases.

If the C content of the cold rolled plate is more than 0.008%, decarburization can be carried out in a mixed atmosphere of order and hydrogen for 10 minutes or less with dew point of 20-70 ℃ before high temperature annealing. If the content is 0.003% or more, the demand may be heat-treated in a decarburized atmosphere during stress relief annealing.

Insulation coating may be performed after the cold rolled sheet is hot annealed, and when the coating is not carried out, demand may be blued.

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

Example 1

Steel slabs prepared in the steelmaking process as shown in Table 1 are heated at 1220 ° C. and hot rolled as shown in Table 2 to a thickness of 2.3 mm, followed by winding and annealing, followed by cold rolling to a thickness of 0.5 mm. It was.

Next, the cold rolled cold rolled plate as described above was carried out for 3 minutes at an annealing temperature of Table 2 in an atmosphere of 20% hydrogen and 80% nitrogen mixed gas.

Next, the cold-rolled sheet annealing material was subjected to stress relief annealing at a temperature of 790 ° C. and 100% nitrogen atmosphere for 2 hours, and then the magnetic properties were measured for each, and the measurement results are shown in Table 2 below.

TABLE 1

TABLE 2

(*) W15 / 50 (W / kg): Iron loss when magnetized to 1.5 Tesla at 50 Hz

B 50 (Tesla): Induced magnetic flux density when magnetized at 5000A / m

u 1.5: Permeability when magnetized to 1.5 Tesla at 50 Hz

As shown in Table 2 above, the inventive material (1-4) manufactured by the inventive steel (ad) corresponding to the component range of the present invention in accordance with the present invention is out of the component range of the present invention ( It can be seen that the magnetic properties are superior to the comparative material (1-7) prepared using ae) as a starting material.

On the other hand, as a result of measuring the grain size for each specimen of Table 2, Comparative materials 1,2 and 3 were 5㎛, 56㎛ and 47㎛, respectively, 56-63㎛ in the case of the comparative materials (4-7) In the case of Inventive Material (1-4), the value of the range was in the range of 65-98 μm.

That is, the grain size of this invention material (1-4) has a large value compared with the thing of the comparative materials (1-7).

Example 2

After re-heating the slab with different contents of Cu and Sn at 1200 ° C. as shown in Table 1, the finish rolling was finished at 850 ° C. to a thickness of 2.3 mm, wound at 700 ° C., and then annealed the hot rolled plate for 800 ° C. for 3 hours. And then pickled.

After pickling, the hot rolled plate was cold rolled to a thickness of 0.5 mm, and then magnetically measured at 950 ° C. for 2 minutes at high temperature, and the results are shown in Table 4 together with the cold rolled state.

TABLE 3

TABLE 4

(*) W15 / 50 (W / kg): Iron loss when magnetized to 1.5 Tesla at 50 Hz

B 50 (Tesla): Induced magnetic flux density when magnetized at 5000A / m

u 1.5: Permeability when magnetized to 1.5 Tesla at 50 Hz

As shown in Table 4, the invention steel (ef) corresponding to the component range of the present invention manufactured by the manufacturing conditions conforming to the present invention (5-6) is a comparative steel (out of the component range of the present invention) Compared with the comparative material 8 manufactured by using f) as a starting material, it was found that not only was excellent magnetic property but also good in the cold rolled state.

Example 3

By weight, C: 0.006%, Si: 2.9%, Mn: 0.35%, P: 0.03%, S: 0.005%, Al: 0.2%, N: 0.003%, Sn: 0.11%, Ni: 0.25% and Cu : After reheating the steel slab composed of 0.16% to 1200 ° C., the final temperature at the time of finish rolling was 900 ° C., which is a ferrite phase, hot rolled to a thickness of 2 mm, and wound at 700 ° C., followed by the hot rolled sheet under the conditions shown in Table 5 below. After annealing, pickling, primary cold rolling to thickness of 1.0mm, middle annealing at 900 ℃ for 2 minutes, secondary cold rolling to thickness of 0.5mm with 50% reduction rate, and cold by two stage cold rolling method Rolled.

Next, the cold-rolled final cold rolled plate as described above was subjected to high temperature annealing at 1050 ° C. for 3 minutes and subjected to stress relief annealing at 790 ° C. for 2 hours, and then to measure magnetic properties. The measurement results are shown in Table 5 below. Indicated.

TABLE 5

(*) W15 / 50 (W / kg): Iron loss when magnetized to 1.5 Tesla at 50 Hz

B 50 (Tesla): Induced magnetic flux density when magnetized at 5000A / m

u 1.5: Permeability when magnetized to 1.5 Tesla at 50 Hz

As shown in Table 5, the inventive material (7-9) annealed under the hot-rolled sheet annealing conditions in accordance with the present invention is magnetic compared to the comparative material (9) manufactured by annealing the hot-rolled sheet under the annealing conditions out of the present invention It can be seen that this is excellent.

As described above, the present invention is to provide a non-oriented electrical steel sheet having a low iron loss, high magnetic flux density and high permeability, thereby maximizing the efficiency of sex energy and electrical appliances.

Claims (4)

By weight%, C: 0.02% or less, Si: 1.0 ~ 3.5%, Mn: 1.0% or less, P: 0.10% or less, S: 0.01% or less, N: 0.008% or less, Al: 0.7% or less, Ni: 0.05 ~ 1.0%, Cu: 0.02 ~ 0.5%, Sn or Sb, or one or two of them: 0.02 ~ 0.2%, balance Fe and other unavoidable impurities. . By weight%, C: 0.02% or less, Si: 1.0 ~ 3.5%, Mn: 1.0% or less, P: 0.10% or less, S: 0.01% or less, N: 0.008% or less, Al: 0.7% or less, Ni: 0.05 ~ 1.0%, Cu: 0.02 ~ 0.5%, Sn or Sb, or one or two of them: 0.02 ~ 0.2%, remainder Fe and other unavoidably added impurities, hot rolled, hot rolled annealing, After pickling, 1 stage cold rolling or 1st cold rolling and intermediate annealing followed by 2 stage cold rolling which carries out 2nd cold rolling, it is manufactured by the pulley process of high temperature annealing and stress removal annealing of a cold rolled sheet. Method for producing non-oriented electrical steel sheet having excellent magnetic properties. The method of claim 2, wherein the annealing method of the hot rolled sheet is a continuous annealing method performed for 10 seconds to 20 minutes at a temperature of 700-1100 ℃. The method of claim 2, wherein the annealing method of the hot rolled sheet is a normal annealing method performed at a temperature of 600-1000 ° C. for 30 minutes to 10 hours.