JPH09217118A - Production of particle-oriented silicon steel sheet excellent in magnetic property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a stable particle-oriented silicon steel sheet excellent in magnetic properties. SOLUTION: In the method for producing a particle-oriented silicon steel sheet, after final cold rolling, the coercive force, permeability or hysteresis loss of a steel sheet before the start of primary recrystallization is regulated to the specified range. Otherwise, the coercive force, permeability or hysteresis loss of the steel sheet is measured, and, in accordance with the deviation between the measured value and objective value, at least one treatment selected from the regulation of the conditions of primary recrystallization annealing, the regulation of the coating weight and componental compsn. of a separation material for annealing and the regulation of the conditions of secondary recrystallization annealing is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a grain-oriented silicon steel sheet having excellent magnetic properties which is used as an iron core material for transformers and the like.

[0002]

2. Description of the Related Art Grain-oriented silicon steel sheets are used as iron core materials for various types of transformers, which have an easy magnetization axis in the rolling direction with the orientation of the crystal grains constituting the material (110) [00
1] It is a highly integrated azimuth, the so-called Goth azimuth. This degree of integration appears in the magnetic flux density characteristics of the steel sheet, and is generally evaluated by the value of B ₈ (T), which indicates the magnetic flux density in a magnetic field of 800 A / m.

A phenomenon called secondary recrystallization is used as a method of integrating in the Goss orientation. That is, in the thermal growth process of normal crystal grains (this is called primary recrystallized grain), the abnormal grain growth behavior with extremely strong orientation selectivity is utilized. Controlling the points is important for obtaining good secondary recrystallized grains having a high degree of integration in the Goss orientation.

For that purpose, in the primary recrystallization before the secondary recrystallization, the inhibitory force of the inhibitor for suppressing the texture, the crystal grain size and the crystal grain growth (precipitate which is the dispersed second phase, It is important to maintain an appropriate balance such as the force that suppresses the grain boundary migration due to the segregation of grain boundary segregation components).

These are adjusted to a target state by appropriately controlling the conditions in the hot rolling step, cold rolling step and primary recrystallization annealing step, but in any case, delicate temperature or Since it is required to control the rolling reduction and the surface properties, there were the following problems in industrial production.

That is, defective generation of secondary recrystallization occurs in stripes in the rolling direction, defective generation of secondary recrystallization occurs on the entire surface, and the crystal orientation of the secondary recrystallized grains is goth. Due to the large deviation from the azimuth, the magnetic characteristics were often deteriorated and a large amount of waste was often generated.

Further, even in cases other than the above in which each process condition is extremely strictly controlled, there is always a variation in the magnetic characteristics during the strip passing opportunity in the factory production process, and the yield and the quality guarantee as the product are guaranteed. Was causing problems.

As a technique for eliminating such instability, the primary recrystallized grain size is measured online,
A means for controlling the primary recrystallization annealing conditions so that the primary recrystallized grain size is in an appropriate range is proposed and disclosed in Japanese Patent Application Laid-Open No. 2-267223 (primary recrystallization annealing method for grain-oriented electrical steel sheets). . Further, in Japanese Patent Laid-Open No. 4-337029 (method of primary recrystallization annealing of unidirectional electrical steel sheet), the N content of the steel sheet before final cold rolling is measured to determine the primary recrystallization grain size of 15 to 25 μm. It has been proposed and disclosed to change the primary recrystallization annealing temperature so as to obtain the range of.

As described above, these are due to the fact that the primary recrystallization grain size has a great influence on the secondary recrystallization behavior.
Primary recrystallization annealing conditions (temperature and line speed) in order to control the primary recrystallization grain size within the range where the best magnetic properties are obtained.
Is a technique to stabilize and improve the magnetic properties of the product.However, in reality, the inhibitor's inhibitory power changes due to changes in hot rolling conditions, annealing conditions after cold rolling and its cooling conditions. In such a case, the optimum primary recrystallized grain size changes according to these changes, so that the generation of secondary recrystallization can be suppressed, but the magnetic characteristics cannot be stabilized, which is not practically good. It wasn't working.

In addition, a number of techniques have been proposed so far for obtaining good secondary recrystallization having excellent magnetic properties in relation to the primary recrystallization grain size.

For example, Japanese Unexamined Patent Publication (Kokai) No. 2-182866 (a plate material for unidirectional electrical steel sheets) discloses a means for making the grain size after primary recrystallization annealing 15 μm or more and the coefficient of variation 0.6 or less. No. 6-33141 (a method for producing a grain-oriented electrical steel sheet having excellent magnetic properties) describes an average grain size of 6 after primary recrystallization annealing.
-11 μm, a coefficient of variation of 0.5 or less, and means for increasing the average particle size by 5 to 30% immediately before the start of secondary recrystallization are disclosed, respectively, and JP-A-5-156361 (excellent magnetic properties). In the method for producing a grain-oriented electrical steel sheet), the primary recrystallized grain size after the primary recrystallization annealing until the start of the final finish annealing is 10 to 35 μm. The method for producing a unidirectional electrical steel sheet having a primary recrystallized grain size of 18 to 35 μm is disclosed in Japanese Patent Laid-Open No. 6-172861 (method for producing a thick thick unidirectional electrical steel sheet having excellent magnetic properties). )
Discloses a means for controlling the primary recrystallized grain size to 18 to 30 μm, respectively.

[0012] However, all of these are techniques for producing good secondary recrystallization for improving magnetic properties by controlling the primary recrystallized grain size as an index. The above-mentioned problem of instability of magnetic properties in static production has remained.

Furthermore, the change in the secondary recrystallization behavior due to the change in the texture formation in the hot rolling process and the change in the texture formation in the cold rolling process, which does not inherently depend on the primary recrystallized grain size, is caused. Regarding the problem, a technique has been proposed in which the permeability and the magnetic flux density after the primary recrystallization annealing are measured to evaluate the formation state of the texture.

For example, in Japanese Patent Laid-Open No. 59-50119 (manufacturing method of unidirectional silicon steel sheet having excellent magnetic properties), the magnetic permeability of a steel sheet after primary recrystallization annealing and before applying an annealing separator is measured. However, a technique of adjusting the amount of S compound added to the annealing separator according to the value is disclosed in JP-A-61-170514 (method for producing unidirectional silicon steel sheet having excellent magnetic properties). A technique is disclosed in which the magnetic flux density of the steel sheet after the primary recrystallization annealing and before the application of the annealing separating agent is measured, and the addition amount of S or the like added to the annealing separating agent is adjusted according to the value. These are to improve the magnetic properties by grasping the formation state of the texture of the steel sheet after the primary recrystallization annealing and adjusting the secondary recrystallization conditions by changing the composition of the annealing separator according to the state. It is something to try.

However, since these techniques do not correctly reflect the formation state of the texture of the steel sheet after primary recrystallization annealing, good results were not obtained when actually applied to industrial production. That is, the magnetic permeability and magnetic flux density of the steel sheet after primary recrystallization annealing are a measure of how much the <001> axis, which is the easy axis of magnetization, is oriented in the rolling direction. } <001> azimuth (h, k or o is an arbitrary integer) cannot be distinguished at all. For example, (110) 001 azimuth and (1
00) 001 had the problem of becoming equivalent to the azimuth.

When the magnetic permeability and the magnetic flux density in the direction perpendicular to the rolling are also measured, the above problems can be solved, but <0
01> The crystal orientation that does not own the axis in the measurement direction, for example {111
It is not possible to distinguish between many crystallographic orientations such as the {112} orientation and the {112} <111> orientation. In particular, the {111} <112> orientation is important for the growth of secondary recrystallization, which is a problem. Was there. Thus, unlike the X-ray method, the measurement of the magnetic permeability and the magnetic flux density of the steel sheet after primary recrystallization annealing is not sufficient as an evaluation method of the texture of the steel sheet, and needs to be improved.

[0017]

DISCLOSURE OF THE INVENTION In order to properly control secondary recrystallization in order to improve and stabilize magnetic properties, the present invention aims to control the texture and hot rolled band structure formed in the cold rolling process. Focusing on the importance of adjusting the balance between both the primary recrystallized grain size and the inhibitor suppressive force in addition to adjusting the balance between The characteristics of the final cold-rolled sheet, which represents the balance between the texture formed in the cold rolling process and the hot-rolled band structure, and the primary recrystallized grain size and inhibitor inhibitory power. It is an object of the present invention to propose a method for producing a grain-oriented silicon steel sheet that can obtain unprecedented stable and excellent magnetic properties by a new means that takes into account the characteristics of the steel sheet after primary recrystallization and before secondary recrystallization. To

[0018]

SUMMARY OF THE INVENTION The present invention is designed for various experiments and
As a result of repeated studies, it is completely novel that the coercive force, magnetic permeability, or hysteresis loss of the steel sheet after final cold rolling is extremely useful for predicting the magnetic properties of silicon steel sheet products, and further for improving and stabilizing them. It was achieved by the findings of. That is, the gist of the present invention is as follows.

1) A silicon steel slab is heated and then hot-rolled, and cold-rolled once or twice with an intermediate annealing, followed by decarburization / primary recrystallization annealing, and then annealing. In a method for manufacturing a grain-oriented silicon steel sheet, which comprises applying a separating agent and performing a final finishing annealing consisting of secondary recrystallization annealing and purification annealing, a coercive force of the steel sheet after the final cold rolling and before the primary recrystallization is started, A method for producing a grain-oriented silicon steel sheet having excellent magnetic characteristics, characterized by controlling magnetic permeability or hysteresis loss within a predetermined range (first invention).

2) The control means in the first invention is at least one selected from the adjustment of slab heating conditions, the adjustment of hot rolling conditions, and the adjustment of cold rolling conditions including intermediate annealing. A method for producing a grain-oriented silicon steel sheet having excellent characteristics (second invention).

3) After heating the silicon steel slab, it is hot-rolled, cold-rolled once or twice with an intermediate anneal, and then decarburized and primary recrystallization anneal, followed by annealing. In a method for manufacturing a grain-oriented silicon steel sheet, which comprises applying a separating agent and performing a final finishing annealing consisting of a secondary recrystallization annealing and a purification annealing, a coercive force of the steel sheet after the final cold rolling and before the primary recrystallization annealing, The permeability or hysteresis loss is measured, and the secondary recrystallization annealing conditions are adjusted according to the deviation between the measured value and the target value of coercive force, permeability or hysteresis loss, and the amount and composition of the composition of the annealing separator are applied. And at least one treatment selected from the adjustment of the primary recrystallization annealing conditions, the method for producing a grain-oriented silicon steel sheet having excellent magnetic properties (third invention).

4) After heating the silicon steel slab, it is hot-rolled and cold-rolled once or twice or more with an intermediate anneal, followed by decarburization and primary recrystallization annealing, and then annealing. In a method for manufacturing a grain-oriented silicon steel sheet, which comprises applying a separating agent and performing a final finishing annealing consisting of secondary recrystallization annealing and purification annealing, a coercive force of the steel sheet after the final cold rolling and before the primary recrystallization is started, A method for producing a grain-oriented silicon steel sheet having excellent magnetic properties, characterized by controlling the permeability or hysteresis loss and the coercive force of the steel sheet after the primary recrystallization and before the start of the secondary recrystallization within respective predetermined ranges ( Fourth invention).

5) The control means in the fourth invention is a steel sheet after the final cold rolling and before the start of primary recrystallization, in which the slab heating conditions are adjusted, the hot rolling conditions are adjusted, and cold rolling including intermediate annealing is performed. At least one selected from the adjustment of conditions, which is a steel plate after primary recrystallization and before the start of secondary recrystallization,
Directionality with excellent magnetic properties, which is at least one selected from adjustment of slab heating conditions, adjustment of hot rolling conditions, adjustment of cold rolling conditions including intermediate annealing, and adjustment of primary recrystallization annealing conditions Manufacturing method of silicon steel sheet (fifth invention).

6) After heating the silicon steel slab, it is hot-rolled, cold-rolled once or twice with intervening intermediate annealing, followed by decarburization / primary recrystallization annealing, and then annealing. In a method for producing a grain-oriented silicon steel sheet, which comprises applying a separating agent and performing a final finishing annealing consisting of secondary recrystallization annealing and purification annealing, a coercive force of the steel sheet after final cold rolling and before primary recrystallization annealing, The permeability or hysteresis loss is measured, and the secondary recrystallization annealing conditions are adjusted according to the deviation between the measured value and the target value of coercive force, permeability or hysteresis loss, and the amount and composition of the composition of the annealing separator are applied. At least one treatment selected from the adjustment of the above and the adjustment of the primary recrystallization annealing condition, the coercive force of the steel sheet after the primary recrystallization annealing and before the secondary recrystallization annealing is measured, and the measurement is performed. 1 according to the deviation between the target value and the coercive force target value Magnetic properties characterized by performing at least one treatment selected from the followings: adjustment of secondary recrystallization annealing conditions, adjustment of application amount / component composition of annealing separator, and adjustment of secondary recrystallization annealing conditions. Of excellent grain-oriented silicon steel sheet (sixth invention).

7) After heating the silicon steel slab, it is hot-rolled, cold-rolled once or twice with intervening intermediate annealing, and then decarburized and primary recrystallization annealing, and then annealing. In a method for manufacturing a grain-oriented silicon steel sheet, which comprises applying a separating agent and performing a final finishing annealing consisting of a secondary recrystallization annealing and a purification annealing, a coercive force of the steel sheet after the final cold rolling and before the primary recrystallization annealing, After measuring the magnetic permeability or the hysteresis loss, and adjusting the primary recrystallization conditions according to the deviation between the measured value and the target value of the coercive force, the magnetic permeability or the hysteresis loss, the primary recrystallization annealing is further performed. After that, the coercive force of the steel sheet before the secondary recrystallization annealing is measured, and according to the deviation between the measured value and the target value of the coercive force, the application amount and composition of the annealing separator are adjusted and the secondary recrystallization annealing is performed. At least one process selected from the adjustment of conditions Method for producing oriented silicon steel sheet having excellent magnetic properties, wherein the applied (seventh invention).

8) The coercive force, magnetic permeability, or hysteresis loss is due to online measurement.
A method for manufacturing a grain-oriented silicon steel sheet having excellent magnetic properties according to the invention or the fifth invention (eighth invention).

9) A method for producing a grain-oriented silicon steel sheet having excellent magnetic properties according to the third, sixth or seventh inventions, in which the coercive force, magnetic permeability or hysteresis loss is measured online. 9th invention).

Here, in the present invention, after cold rolling, the band structure of the hot rolled sheet and the state of introduction of dislocations are determined by the coercive force, magnetic permeability or hysteresis loss of the steel sheet (cold rolled sheet) before primary recrystallization annealing. This is to evaluate the formation state of the texture of the cold-rolled sheet, and the difference in the difference in the introduction state of the band structure of the hot-rolled sheet and the dislocation of the cold-rolled sheet is the coercive force in the cold-rolled sheet. This is because it is possible to make a more appropriate evaluation by largely reflecting it on the magnetic permeability or the hysteresis loss.

The texture of the steel sheet after primary recrystallization annealing largely depends on the dislocation introduction state of the steel sheet before primary recrystallization annealing and the texture of the steel sheet before annealing. Under normal operating conditions, The primary recrystallization is better evaluated by the coercive force, magnetic permeability or hysteresis loss of the steel sheet before primary recrystallization annealing than by the magnetic permeability or magnetic flux density of the steel sheet after primary recrystallization annealing of the above-mentioned conventional technology. It is suitable even if it includes disturbance factors of the annealing conditions.

Regarding the coercive force, the coercive force of the steel sheet before primary recrystallization annealing serves as an index indicating the state of introduction of dislocations as described above, but the coercive force of the steel sheet after primary recrystallization annealing is mainly an inhibitor. Is another index showing the suppression state of the magnetic field, and by using this index, the magnetic characteristics can be further improved.

Hereinafter, description will be made on the basis of experimental examples that have achieved the present invention. C: 0.068mass%, Si: 3.35mass
%, Mn: 0.072 mass%, sol Al: 0.024 mass%, S: 0.0
03 mass%, Se: 0.016 mass%, Sb: 0.030 mass%, C
When 10 slabs containing u: 0.15 mass% and N: 0.008 mass% and the balance of Fe and inevitable impurities were used, and heating the slabs to a temperature of 1430 ° C.,
The soaking time was 5 minutes for 5 pieces, and 20 minutes for the other 5 pieces. After heating the slab, rough rolling is performed in the temperature range of 1200 to 1210 ° C.
Hot rolling was performed at a finish rolling outlet temperature in the temperature range of 950 to 1000 ° C to obtain a hot rolled coil with a plate thickness of 2.2 mm.

After that, each coil has a temperature of 1000 ° C. and a time of:
After 1 minute of hot-rolled sheet annealing, cold rolling to a sheet thickness of 1.50 mm, then 1 minute of intermediate annealing at a temperature of 1050 ° C, 70-100 ° C, 120-140 ° C, 150-180 ℃, 200〜
In each of the temperature ranges of 230 ° C. and 250 to 270 ° C., one of each of the two levels of slab soaking time described above was cold-rolled.

These cold-rolled coils were subjected to primary recrystallization annealing which measures demagnetizing force and magnetic permeability of a steel sheet at Hm = 1000 A / m, and which also serves as decarburization annealing in wet hydrogen at a temperature of 850 ° C. for 3 minutes. After that, an annealing separator containing MgO as a main component was applied to perform final finishing annealing.

The magnetic flux density B ₈ (T), the secondary recrystallization ratio, and the (110) [001] orientation of the in-plane crystal orientation of the secondary recrystallized grains of each of the steel sheets thus obtained after the final finish annealing were obtained. The deviation angle (α) was measured and the average primary recrystallized grain size of each steel sheet after the primary recrystallization annealing was measured.

These measurement results are shown in FIG. 1, FIG. 2 and FIG.
Shown in FIG. 1 is a graph showing the relationship between the average primary recrystallized grain size of the steel sheet after primary recrystallization annealing and various properties of the steel sheet after final finish annealing, and FIG. 2 is a coercive force of the steel sheet after final cold rolling ( Hc)
And FIG. 3 is a graph showing the relationship between various properties of the steel plate after final annealing, and FIG. 3 is a graph showing the relationship between the magnetic permeability (μ) of the steel plate after final cold rolling and the properties of the steel plate after final annealing. .

As is apparent from FIG. 1, even if the average primary recrystallized grain size is the same, the magnetic characteristic B ₈ changes greatly, and the magnetic characteristic is not uniquely determined by the average primary recrystallized grain size. I understand. That is, unlike the above-mentioned conventional technique, the means for controlling the average primary recrystallization grain size cannot properly obtain the secondary recrystallization having excellent magnetic characteristics.

On the other hand, in FIG. 2 or FIG. 3, even if the slab heating temperature or cold rolling temperature changes, only the coercive force (Hc) or magnetic permeability (μ) of the steel sheet after final cold rolling is used. The magnetic property B ₈ after the secondary recrystallization was determined. In FIG. 2, the coercive force is in the range of 535 to 545 (A / m) or in FIG.
Shows that good magnetic characteristics can be obtained when the magnetic permeability is in the range of 0.53 to 0.56 (× 10 ⁻³ H / m).

Therefore, if this coercive force or magnetic permeability is used as an index, the magnetic characteristics after final finish annealing can be predicted with extremely accurate reproducibility.

Here, the reason why such a result is obtained will be considered. It is generally known that when a slab is heated to a high temperature of 1430 ° C. or higher, the inhibitor dissolves in an extremely short time, and there is no difference in solid solution of the inhibitor between the soaking time of 5 minutes and 20 minutes. Also, since there is no difference in the temperature conditions of hot rolling, there is no difference in precipitation dispersion of the inhibitor. This was also confirmed by the results of measuring the inhibitory potency of both inhibitors.

Therefore, the difference between the two is the crystal grain size after heating the slab. According to the examination of the crystal grain size of the slab after heating, when the soaking time was 5 minutes, the crystal grain size was 15 to 30 mm. On the other hand, when the soaking time was 20 minutes, the crystal grains grew to a size of 50 to 80 mm. The size of the slab crystal grains before the hot rolling is related to the development of the hot rolled band structure after the hot rolling. The larger the slab crystal grains, the more the hot rolled band structure develops.

When the degree of development of the hot-rolled band structure is weak, it is considered that the development of the (110) texture of the primary recrystallization texture is weak, and conversely, the degree of the development of the hot-rolled band structure. If the value is strong, the development of the (111) texture in the primary recrystallization texture is inhibited. Therefore, in order to obtain good magnetic properties in the product plate, it is important to optimize the degree of development of the hot rolled band structure, and for that purpose it is important to optimize the size of the slab crystal grains. become.

Further, changing the temperature of cold rolling changes the deformation behavior during cold rolling and changes the primary recrystallization texture. Therefore, both of them aim for the same effect, and by maintaining an appropriate balance,
It is possible to obtain the best magnetic characteristics.

Factors that influence the primary recrystallization texture include not only the slab soaking temperature and cold rolling temperature, but also the rolling ratio in rough rolling and finish rolling in hot rolling and in steel. C content, carbide size, intermediate annealing, cold rolling reduction, rolling speed, number of times of rolling, friction during rolling, aging between rolling passes,
There are various rolling tensions, and it is important to adjust these.

By the way, there are X-ray diffractometry and the like as a method for measuring the primary recrystallization texture, but there is no simple method. Therefore, in the present invention, the coercive force, magnetic permeability, or hysteresis loss of the steel sheet after the final cold rolling is measured based on the above experimental results.

That is, the dislocations existing in the steel sheet after the final cold rolling are different depending on the behavior at the time of deformation and the crystal structure before rolling.
The accumulation state is different, which affects the primary recrystallization texture. For example, when subjected to cold rolling deformation at a high temperature, high dislocations are accumulated and a (110) texture develops as a primary recrystallization texture. The present invention is based on the finding that the degree of dislocation integration introduced by such cold rolling can be easily estimated by measuring the coercive force, magnetic permeability or hysteresis loss of the steel sheet after final cold rolling.

Therefore, the coercive force and the coercive force of the steel sheet after the final cold rolling are changed by changing the conditions of various factors in the slab heating step, hot rolling step, and cold rolling step that affect the above-mentioned primary recrystallization structure. It is possible to bring the magnetic permeability or the hysteresis loss close to the target value.

On the other hand, the state of the steel sheet after the final cold rolling can be estimated by measuring these coercive force, magnetic permeability or hysteresis loss, and the hot rolled band structure and the accumulation of dislocations introduced by cold rolling are estimated. The inventor's knowledge that it is important to adjust the balance of degrees makes it possible to take easy and appropriate measures for the subsequent processing of the steel sheet.

For example, when the coercive force is higher than the target value or when the magnetic permeability is higher than the target value, the dislocations introduced into the steel are excessively accumulated, so that the temperature rising rate of decarburization annealing is reduced. Yes, the soaking temperature is lowered, or the temperature rising rate of final finish annealing is increased. Delay the switching time from the neutral atmosphere to the reducing atmosphere in the final finish annealing, and further reduce the coating amount of the annealing separator, or add TiO ₂ , Sr (OH) ₂ to the annealing separator. Measures such as reducing the amount of 8H ₂ O and SnO ₂ added or canceling the addition are effective. These are measures to weaken the development of the (110) system recrystallization texture that is formed when dislocation accumulation is excessive, and to promote the development of the (111) system recrystallization texture. Further, when the coercive force, the magnetic permeability, or the hysteresis loss is lower than the target value, it is possible to achieve the balance with the suppression force by taking the opposite measure.

Further, in addition to the technique of stabilizing the recrystallized texture by balancing the degree of dislocation integration, it is not possible to add a technique of balancing the inhibitory force of the inhibitor and the primary recrystallized grain size. It is more preferable for obtaining a product having excellent magnetic properties. In order to do so, the coercive force of the steel sheet after primary recrystallization is adjusted to a target value and maintained constant, or the primary recrystallization annealing conditions are adjusted according to the deviation from the target value, and the amount of the annealing separator applied is adjusted. It is advisable to take measures to either adjust the component composition or the secondary recrystallization annealing conditions.

[0050]

BEST MODE FOR CARRYING OUT THE INVENTION The operation of the present invention will be described below.
The grain-oriented silicon steel sheet that is the subject of the present invention is a molten steel obtained by a steelmaking method that has been conventionally used, is cast by a continuous casting method or an ingot making method, and is a slab through a slab step, if necessary, After hot rolling the slab into a hot rolled sheet,
Cold rolling is performed once or more than twice with an intermediate anneal between them to obtain the final sheet thickness, then after primary recrystallization annealing that also serves as decarburization, an annealing separator is applied to perform secondary recrystallization annealing and purification. It is manufactured by performing final finishing annealing consisting of annealing.

The preferred composition range of the composition of the grain-oriented silicon steel slab is as follows.

When C exceeds 0.20 mass%, decarburization becomes difficult, so the content is preferably 0.20 mass% or less.

If Si is less than 2.0 mass%, the specific resistance is too low to obtain the desired iron loss, while if it exceeds 7.0 mass%, rolling becomes difficult. Therefore, its content is 2.0 mass
% Or more and 7.0 mass% or less is preferable.

Mn needs to be 0.02 mass% or more as an inhibitor component such as MnS and MnSe and for improving the hot rolling property, but if it exceeds 3.0 mass%, the effect on the γ transformation becomes large, and Secondary recrystallization becomes unstable. Therefore, its content is preferably 0.02 mass% or more and 3.0 mass% or less.

In order to obtain good secondary recrystallization having excellent magnetic properties, it is preferable to contain one or more selected from S, Se, Al, Te and B known as inhibitor components in addition to the above components. Is important to. In order to obtain more stable secondary recrystallization, Cu, Ni, Sn, Sb, As, Bi, Cr, M
One or more selected from o, P and N may be contained.

Next, with respect to the coercive force, magnetic permeability, or hysteresis loss of the steel sheet after final cold rolling, which is a feature of the present invention, the measuring method and control method thereof will be described. First, as the measuring method, a method of cutting and measuring the steel sheet after the final cold rolling (off-line measuring method) or a primary coil and a secondary coil are installed in a cold rolling line or a primary recrystallization annealing line, Pass a steel strip through the coil,
There is a method (online measurement method) of magnetizing the steel strip by bringing it into contact with the surface of the steel strip, but the latter is superior as the control method.

Coercive force, magnetic permeability, or hysteresis loss is measured by applying a constant maximum magnetizing force, measuring by applying a constant maximum magnetic flux density, and measuring by magnetizing to a region close to the saturation magnetic flux density. Any method is suitable for this invention. Further, as a method for changing the magnetic field, either a quasi-static changing method (DC method) or an alternating changing method (AC method) is suitable for the present invention.

Further, as a method of applying magnetization, it is possible to use a magnet instead of the primary coil. In addition,
The product of coercive force and magnetic permeability, that is, the amount corresponding to hysteresis loss can also be measured.

The value of the coercive force, magnetic permeability or hysteresis loss of the steel sheet after final cold rolling measured by such a method allows the final cold rolling to exhibit excellent magnetic properties in the product subjected to final finish annealing which has been measured in advance. Coercive force of the later steel plate,
The optimum range of magnetic permeability or hysteresis loss is defined as a predetermined range, and control is performed to fall within this range. The coercive force, as a control means of magnetic permeability or hysteresis loss, from the slab heating step to the cold rolling step, there is each treatment condition that becomes a factor that changes the above-mentioned coercive force, magnetic permeability or hysteresis loss, At least one selected from these may be adjusted.

More preferably, a target value for the coercive force, magnetic permeability or hysteresis loss of the steel sheet after final cold rolling is set within the above predetermined range, and this target value and the coercive force, permeability of the steel sheet after final cold rolling are set. By comparing the measured values of magnetic susceptibility or hysteresis loss, the primary recrystallization annealing conditions are adjusted, the amount of the annealing separating agent applied and the composition of the components are adjusted according to the deviation between the two, and
It is preferable to perform at least one of the adjustments of the secondary recrystallization annealing conditions. By doing so, a product having stable and excellent magnetic properties can be obtained.

Here, when the measured coercive force, magnetic permeability or hysteresis loss is smaller than the target value, the development of the hot-rolled band structure is insufficient, or the dislocations in the steel sheet after the final cold rolling are observed. Since the degree of integration is too low,
Process by any one or more of E.

1. Adjustment of primary recrystallization annealing conditions A. Increase the heating rate between 500 and 800 ℃. B. Increase oxygen potential during soaking.

2. Adjusting the composition of the amount of annealing separator applied C. Increase the amount of annealing separator applied. D. TiO ₂ , Sr (OH) ₂ · 8H ₂ O, SnO ₂ , Fe ₂ O ₃ , NiO, CuO ₂ ,
An oxide such as CoO is contained in the annealing separator, or its content is increased.

3. Adjustment of secondary recrystallization annealing conditions E. Extend the heat treatment time from 800 ℃ to the start of secondary recrystallization.

On the other hand, when the coercive force, magnetic permeability, or hysteresis loss measured on the contrary is larger than the target value, the hot-rolled band structure has developed, or the dislocation integration in the steel sheet after the final cold rolling is excessive. Therefore, any one or more of the measures reverse to A to E described above may be applied.

In the above, the measures A to E, which are carried out when the measured coercive force, magnetic permeability or hysteresis loss are smaller than the target values, all promote the development of (110) recrystallization texture, ) It is a means to suppress the development of recrystallized texture, and conversely, when the coercive force, magnetic permeability or hysteresis loss is larger than the target value, the reverse measures of A to E are all (110) Suppresses the development of crystal texture,
It is a means to promote the development of (111) recrystallization texture.

As described above, in the present invention, the coercive force,
By using an index such as magnetic permeability or hysteresis loss, it was possible to evaluate a composite of two factors that affect secondary recrystallization, that is, a hot rolled band structure and a recrystallization texture. Therefore, the best 2
In order to control the secondary recrystallization, the adjustment amounts of the measures A to E and vice versa are set accurately and quantitatively according to the deviation from the target coercive force, magnetic permeability, or hysteresis loss. Needless to say, is important.

The reduction of the deviation of the coercive force, the magnetic permeability or the hysteresis loss, or the adjustment of the process condition according to the deviation amount is performed not only for each coil but also for each portion in the coil. The good thing is self-evident.

Further, in combination with such a technique, after the primary recrystallization, the value of the coercive force of the steel sheet was measured in advance until the start of the secondary recrystallization, and the product obtained after the final finish annealing showed excellent magnetic properties. It is also effective to further improve the magnetic characteristics by controlling the coercive force of the primary recrystallizable plate that can be expressed so as to fall within a predetermined range.

As a means for controlling the coercive force, there is a means for changing the processing condition that causes the change in the coercive force between the slab heating step and the cold rolling step. Of at least one of the above, the adjustment of the component composition of the annealing separator and the adjustment of the secondary recrystallization annealing conditions, and more preferably, the coercive force of the primary recrystallization plate within the above predetermined range. Then, the target value is determined and the target value is compared with the measured value of the coercive force of the steel sheet after the primary recrystallization annealing, and the primary recrystallization annealing condition is changed and the annealing separator is It is preferable to perform at least one treatment from the adjustment of coating amount / component composition and the adjustment of secondary recrystallization annealing conditions.

By doing so, a product having stable and excellent magnetic properties can be obtained.

If the measured coercive force is smaller than the target value, is the inhibitory force of the inhibitor reduced?
Since the secondary recrystallized grain size is too large, any one or more of the following measures a to m should be taken.

1. Change of primary recrystallization annealing conditions a. Increase oxygen potential during temperature rise. b. Decrease the heating rate. c. Reduce the oxygen basis weight. d. Reduces subscale firelite / silica ratio. e. Lower the soaking temperature. f. Reduce soaking time. g. Reduce the amount of nitriding or denitrify (for grain-oriented silicon steel sheets containing Al).

2. Adjustment of coating amount and component composition of annealing separator h. Increase the amount of annealing separator applied. i. SrSO ₄ , MgSO ₄ , SnSO ₄ , Na ₂ SO ₄ , CaSO ₄ , FeSO ₄ , NiS
Sulfate compounds such as O ₄ and CoSO ₄ are included in the annealing separator or their content is increased. j. In the case of grain-oriented silicon steel sheet containing Al, FeN, S
A nitride such as iN ₄ , Fe _x N, (Mn, Fe) _x N, TiN and CrN is contained in the annealing separator or the content thereof is increased.

3. Adjustment of secondary recrystallization annealing conditions k. Increase heating rate. l. 750-950 for grain-oriented silicon steel sheet containing Sb
The temperature of the isothermal holding treatment for secondary recrystallization or secondary recrystallization nucleation between the temperatures of ° C is increased.

M. In the case of a grain-oriented silicon steel sheet containing Al, the H ₂ partial pressure in the atmosphere until the start of secondary recrystallization is lowered.

On the other hand, when the coercive force measured on the contrary is larger than the target value, either the primary recrystallized grain size is too small or the inhibitory force of the inhibitor is too large. One or more of the countermeasures may be taken.

In the above, the measures a to m to be taken when the measured coercive force is smaller than the target value are all means for increasing the coercive force before the start of secondary recrystallization including the primary recrystallization annealing. On the contrary, when the coercive force is larger than the target value, the reverse measures a to m are all means for decreasing the coercive force before the start of secondary recrystallization including the primary recrystallization annealing. It has become.

As described above, by using the index of coercive force, the inhibitory force of the inhibitor and the primary recrystallized grain size, the two factors of the steel sheet after primary recrystallization annealing, which influence the secondary recrystallization are combined. It was possible to evaluate it.

Therefore, in order to control the secondary recrystallization that is the best, a.about. Depending on the deviation from the target coercive force.
It goes without saying that it is important to accurately and quantitatively set the adjustment amount for the measure of m and the opposite.

The present invention also prevents the simultaneous use of the technique of forming a groove on the surface of the steel sheet or locally applying strain to reduce the magnetic domain width of the grain-oriented silicon steel sheet to improve the iron loss. Not a thing. In the above, as a means for providing a groove, an etching method or a processing method using a protrusion roll, and as a means for adding strain, irradiation with a pulsed or continuous laser beam,
Any conventionally known means such as irradiation with a plasma jet and pressing of a rotating ball are suitable.

[0082]

【Example】

Example 1 C: 0.07 mass%, Si: 3.26 mass%, Mn: 0.07 mass%, so
l Al: 0.024 mass%, S: 0.003 mass%, Se: 0.018 mas
s%, Sb: 0.035 mass%, Cu: 0.10 mass%, Mo: 0.010 ma
14 slabs containing ss% and N: 0.007 mass% 14
It was heated to a temperature of 00 ° C and hot-rolled by a known method to obtain hot-rolled sheet coils each having a sheet thickness of 2.0 mm.

Then, hot-rolled sheet annealing was carried out at a temperature of 1150 ° C. for a time of 50 s, and the temperature was cooled to room temperature in the cooling rate range of 15 to 100 ° C./s. After that, pickle and use a Zenzimer rolling mill.
Cold rolling in the temperature range of 80 to 250 ℃, 0.26
The final plate thickness was mm.

The 24 cold-rolled coils thus obtained were grouped into 12 coils. The first 12 coils have a dew point:
55 ℃, H ₂ : 60% balance in N ₂ atmosphere, heating rate: 15 ℃ / s,
Soaking temperature: 800 ℃, soaking time: After having been subjected to decarburization and primary recrystallization annealing of the 120s, the main component _{MgO, Sr (OH) 2 ·} 8H
An annealing separator containing ₂ O: 3%, TiO ₂ : 10%, SnO ₂ : 5% was applied to the steel sheet surface (both sides) at 10 g / m ² and then wound into a coil to perform final finishing annealing with N ₂ Temperature: 840 ℃ in the atmosphere, heating rate: 30 ℃ / h, and hold at 840 ℃ for 45 hours, then in an atmosphere of N ₂ : 25%, H ₂ : 75%, temperature: 1150 ℃
Heating rate up to 15 ℃ / h, then in H ₂ atmosphere
It was kept at a temperature of 1150 ° C. for 5 hours and then cooled.

After that, the unreacted annealing separating agent was removed, and the tension coating agent was applied also for flattening annealing, and the baking treatment was performed in an N ₂ atmosphere at a temperature of 800 ° C. and a holding time of 90 s. It was made into a product (comparative example).

The next 12 coils are 80 to 80 in the same manner as in the comparative example.
After cold rolling in the temperature range of 250 ℃, cut out steel sheet pieces, measure the coercive force and magnetic permeability of each piece, and obtain the maximum magnetizing force H that gives the best magnetic properties in the laboratory.
= 1000 A / m, coercive force: 540 A / m, and permeability: 0.54
Values of H / m × 10 ⁻³ were obtained, and these values were used as the target coercive force and magnetic permeability.

Thereafter, for the 6 coils, the first 3 coils were subjected to the same decarburization and primary recrystallization annealing as in the comparative example, depending on the difference between the target coercive force and the coercive force of each coil. Using the annealing separator having the same composition as the comparative example, changing the coating amount, the final finishing annealing was made completely the same as the comparative example, and the remaining 3 coils were the same decarburization / primary as the comparative example. After applying the recrystallization annealing conditions and the annealing separator, in the final finishing annealing conditions, only the time of holding at the temperature of 840 ° C was changed, and other than that, the final finishing annealing was performed under the same conditions as the comparative example. . Regarding the remaining 6 coils, depending on the difference between the target magnetic permeability and the magnetic permeability of each coil, the first 3 coils have the same decarburization and primary recrystallization annealing as in the comparative example, but 500 to 800. The temperature rising rate between ° C was changed, the annealing separator and the final finish annealing were exactly the same as in the comparative example, and the following three coils were annealed after the same decarburization and primary recrystallization annealing as in the comparative example. The content of SnO ₂ in the separating agent was adjusted, and the final finish annealing was the same as that of the comparative example.

After removing the unreacted separating agent, each of these coils was coated with a tension coating agent also for flattening annealing, and baked under the conditions of atmosphere: N ₂ , temperature: 800 ° C., time: 90 s. (Compliance example of this invention). The secondary recrystallization temperature of the steel sheet after the primary recrystallization annealing is 1100 ° C.

The magnetic properties (magnetic flux density, iron loss) measured for these products are summarized in Table 1.

[0090]

[Table 1]

As is apparent from Table 1, the conforming example of the present invention has excellent magnetic characteristics as compared with the comparative example, and the variation between the coils is extremely small and shows a stable value.

Example 2 C: 0.07 mass%, Si: 3.35 mass%, Mn: 0.07 mass%,
P: 0.07 mass%, S: 0.003 mass%, Se: 0.018 mass
%, Sb: 0.02mass%, Mo: 0.01mass% and N: 0.008
Eight steel slabs containing mass% were heated at a temperature of 1350 ° C. for 60 minutes and then subjected to ordinary hot rolling to obtain a hot-rolled coil having a plate thickness of 2.4 mm.

Each of these hot-rolled sheet coils was divided into 6 to make a total of 48 coils. After that temperature: 1000 ℃, time: 60s
After the hot rolled sheet is annealed and cold-rolled to a thickness of 1.50 mm, the former is temperature: 830 ° C, time: 30 s, the latter is temperature: 1050 ° C, time: 60 s Annealing,
Dew point: 50 ° C, H ₂ : 50%, balance: N ₂ atmosphere, quench with mist water to a temperature of 350 ° C at a rate of 40 ° C / s, and then hold at a temperature of 350 ° C for 20s After that, it was subjected to a pickling treatment in a pickling bath at a temperature of 80 ° C.

Thereafter, each coil is cold-rolled in a temperature range of 100 to 230 ° C. to obtain a cold-rolled plate coil having a final plate thickness of 0.22 mm, and each coil is online when the final rolling of the cold rolling is passed. The change in coercive force in the longitudinal direction of the coil was measured. After that, the surface of the steel sheet was partially coated with an electrically insulating resist ink and electrolytically etched.On one surface of the steel sheet, at a direction of 85 ° to the rolling direction, width: 100 μm, depth: 25 μm After performing a treatment for forming grooves at a pitch of 3 mm in the rolling direction, the resist ink was removed, decarburization and primary recrystallization annealing were performed, an annealing separator was applied, and the coil was wound on a coil.

The conditions of decarburization and primary recrystallization annealing are as follows: dew point: 50
℃, H ₂ : 50% balance in N ₂ atmosphere, heating rate: 10 ℃ / s, soaking temperature: 845 ℃, soaking time: 120 s, under the fixed conditions, mainly MgO, TiO 2 _2: 8%, SrSO _4: was 8 g / m ² coated annealing separator surface of the steel sheet containing 3% (two-sided).
At this time, in the first 16 coils, as a comparative example, only the coercive force was measured, and the measurement result was not reflected in any process condition.

The following 16 coils, as a conforming example I, set the rolling temperature in the final pass of cold rolling to the longitudinal direction of the coil so that the deviation between the measured value of the coercive force and the appropriate target value of the coercive force becomes zero. In the direction, control was performed to change the oil amount of the roll coolant according to the deviation amount of the coercive force.

The remaining 16 coils, as a conforming example II, were to change the coating amount of the annealing separator in the longitudinal direction of the coil according to the deviation between the measured value of the coercive force and the target value of the appropriate coercive force. , Was performed by changing the squeezing pressure of the coating roll.

Thereafter, these coils were subjected to final finishing annealing in a N ₂ atmosphere at a temperature rising rate of 850 ° C. and a heating rate of 30 ° C./h.
After heating at 850 ° C for 35 hours, N ₂ : 35
%, H ₂ : 65%, temperature: up to 1150 ℃ Temperature rising rate: 3
The temperature was raised at 0 ° C./h, and then the temperature was maintained at 1150 ° C. for 5 hours in an H ₂ atmosphere and then cooled. After that, the unreacted annealing separator was removed, a tension coating agent was applied also for flattening annealing, and a baking treatment was performed in an N ₂ atmosphere at a temperature of 800 ° C. for a time of 90 s to obtain each product.

Table 2 shows the average value and standard deviation of the coercive force of the steel sheet after the final cold rolling of each of the 16 coils and the average value of the magnetic properties of the product sheet for these products.

[0100]

[Table 2]

In Table 2, the conforming examples I and II conforming to the present invention show excellent magnetic property values as compared with the comparative examples. As a matter of course, the standard deviation of the coercive force of the steel sheet after cold rolling of the conforming example I is smaller than that of the comparative example and the conforming example II.

Example 3 Each of steel slabs having four kinds of target component compositions A to D shown in Table 3
60 pieces, steel types A and B at a temperature of 1400 ℃, C and D
Was heated to a temperature of 1300 ° C and then hot-rolled by a conventional method to form hot-rolled sheet coils of 2.2 mm each.

[0103]

[Table 3]

These coils were subjected to hot rolled sheet annealing at a temperature of 1000 ° C. for 30 seconds. After that, it is rapidly cooled in a mist, cold-rolled to a plate thickness of 1.50 mm, and then again at a temperature of 1080 ° C for 1
After intermediate annealing for 1 minute, it was rapidly cooled in a mist and cold-rolled in a temperature range of 140 to 250 ° C to obtain cold-rolled sheets with a final sheet thickness of 0.22 mm.

After that, for each of the steel types A to D, 30 coils were
Dew _{point: 60 ℃, H 2: 50} % balance temperature in an atmosphere of N _2: 850
Decarburization / primary recrystallization annealing at 120 ° C for 120s, 13g / m of steel sheet surface (both sides) with an annealing separator containing MgO as the main component and containing TiO ₂ : 5% and SrSO ₄ : 3%. ^Two coats were applied and wound into a coil.

After that, it was heated in an N ₂ atmosphere to a temperature of 850 ° C. at a heating rate of 40 ° C./h, and then N ₂ : 20% and H ₂ :
850 for steel types A, B and C in 80% atmosphere
Temperature range from ℃ to 1150 ℃ is 30 ℃ / h, and for steel type D, the temperature range is from 850 ℃ to 1000 ℃ is 15 ℃ / h. Final finishing annealing was carried out by holding C and C at a temperature of 1150 ° C. and Steel type D at a temperature of 1000 ° C. for 5 hours.

Thereafter, after removing the unreacted annealing separator, each of these coils was coated with a tension coating agent also for flattening annealing, and in a N ₂ atmosphere, temperature: 800 ° C., time: 90 s
Each of them was baked to obtain a product (comparative example).

On the other hand, of the remaining 60 coils of steel types A to D,
For 30 coils, the optimum permeability of the steel sheet after the final cold rolling was obtained in advance in the laboratory, this value was set as the target permeability, and it was installed at the position immediately before decarburization and primary recrystallization annealing. The magnetic permeability of each coil was measured by the online magnetic permeability measuring device, and the oxygen potential PH ₂ O / PH ₂ of the soaking part of the decarburization / primary recrystallization annealing was measured according to the deviation from the target magnetic permeability. The process conditions were optimized by either one of the changes and the change in the amount of the annealing separator applied or a combination of the two.

In the above changes, PH ₂ O / PH ₂ was changed by changing the flow rate of steam injected into the furnace, and the amount of the annealing separator applied was changed by the annealing separator applying roll installed on the outlet side of the annealing furnace. It was performed by changing the tightening pressure of.

Thus, after the final finish annealing, after removing the unreacted annealing separator, the tension coating agent was applied also for flattening annealing, and the temperature was set to 800 ° C. in a N ₂ atmosphere.
A baking process was performed for a time of 90 s to obtain a product (Compliant example I of the present invention: standalone type).

Next, for each of the remaining 30 coils of the steel types A to D, the optimum magnetic permeability of the steel sheet after the final cold rolling was obtained in advance in the laboratory, and this value was set as the target magnetic permeability and demagnetized. The magnetic permeability of each coil is measured by an online magnetic permeability measuring instrument installed immediately before the charcoal / primary recrystallization annealing, and the decarburization / primary recrystallization annealing of 500 to 8 is performed according to the deviation from the target magnetic permeability.
The rate of temperature increase between 00 ° C was changed.

Further, the optimum coercive force of the steel sheet after decarburization / primary recrystallization annealing was obtained in advance, this value was set as the target coercive force, and it was installed at the position immediately after decarburization / primary recrystallization annealing. The coercive force of each coil was measured by an online coercive force measuring device, and the composition of the annealing separator was changed according to the deviation from the target coercive force. This compositional change was performed by changing the content of SrSO ₄ contained in the annealing separator.

Other decarburization / primary recrystallization annealing conditions, annealing separator application conditions, and final finishing annealing conditions were the same as those of the comparative example.

[0114] Thus, after the final annealing, after removal of the unreacted annealing separator, respectively, the tension coating agent is applied also as a flattening annealing, the temperature in an N ₂ atmosphere: 800
The product was baked at 90 ° C for 90 s to obtain a product (Compliance example II of the present invention: combination type).

Table 4 shows the average values of the magnetic properties measured for these products for each steel type and each manufacturing method.

[0116]

[Table 4]

As is clear from Table 4, the magnetic properties of the conforming example of the present invention were significantly improved as compared with the comparative example. Particularly, the magnetic permeability of the steel sheet after the final cold rolling was measured, and the value The decarburization / primary recrystallization annealing conditions or the amount of the annealing separator applied are changed based on the above, and the coercive force of the steel sheet after decarburization / primary recrystallization annealing is measured. The magnetic properties of the adjusted conformation example II are significantly improved. This is nothing but the result that the inhibitory power of the inhibitor and the consistency between the cold rolling process conditions and the compatibility between the hot-rolled band structure and the cold rolling process conditions were simultaneously satisfied.

Example 4 30 steel slabs having the target composition of A shown in Table 3 above were used as 14
After heating to a temperature of 00 ° C., hot rolling was carried out by an ordinary method to obtain a hot rolled sheet having a plate thickness of 2.6 mm.

15 of these coils are 1150
Annealed hot rolled sheet for 30 seconds at ℃, then in mist
After quenching at a cooling rate of 30 ° C./s, it was cold-rolled at a temperature of 180 to 220 ° C. using a Zenzimer rolling machine to obtain a final plate thickness of 0.34 mm. After measuring the coercive force when the maximum magnetizing force of this steel sheet was 2000 A / m, decarburization was carried out in an atmosphere of dew point: 60 ° C, H ₂ : 50% balance N ₂ at a temperature of 850 ° C and a time of 120 s. Recrystallization annealing was performed, and the coercive force of this steel sheet at the maximum magnetic flux density of 1.5 T was measured. Thereafter, an MgO as a main _{component, TiO 2: 8%, SnO} 2:
Annealing agent containing 3% is applied to the steel plate surface (both sides) at 10 g / m ²
It was applied and wound into a coil.

Thereafter, the sample was heated in an N ₂ atmosphere to 850 ° C. at a temperature rising rate of 40 ° C./h, and then in an atmosphere of N ₂ : 30% and H ₂ : 70% up to 1150 ° C. 15 ° C. / The temperature is raised at a heating rate of h,
A final finish annealing was carried out in a H ₂ atmosphere at a temperature of 1150 ° C. for 8 hours.

Then, after removing the unreacted separating agent, a tension coating agent was applied also for flattening annealing, and baked in a N ₂ atmosphere at a temperature of 800 ° C. for a time of 90 s to obtain a product ( Comparative example).

On the other hand, for the remaining 15 hot-rolled sheet coils, a small sample was cut out from the coil and processed in the laboratory under the same process conditions as the comparative example, and the maximum magnetizing force of the steel sheet after cold rolling was 2000 A / m.
The coercive force at the time of, the coercive force at the maximum magnetic flux density of 1.5 T of the steel sheet after decarburization and primary recrystallization annealing, and the magnetic properties of the final treated product were measured. The coercive force of the cold rolled steel sheet of the sample with the best magnetic properties: 658A / m as the target coercive force of the steel sheet after cold rolling, the cold rolling temperature was changed, and By changing the temperature of hot-rolled sheet annealing, the coercive force of the steel sheet after decarburization / primary recrystallization annealing of the excellent sample was set as the target coercive force of the steel sheet after decarburization / primary recrystallization annealing. Under the same process conditions as the comparative example (excluding the hot-rolled sheet annealing temperature and the cold rolling temperature) so as to meet the target value, these
15 coils were processed and made into a product (compliance example).

Table 5 shows the magnetic characteristics of the products of the comparative example and the conforming example, and the average value and standard deviation of the coercive force of the intermediate process products.
Are shown together.

[0124]

[Table 5]

As is clear from Table 5, as compared with the comparative example,
The magnetic properties of the conforming example of the present invention are significantly improved, and the coercive force of the steel sheet after final cold rolling and the coercive force of the steel sheet after decarburization / primary recrystallization annealing are controlled to target values. It shows that the method of the invention is superior.

Example 5 8 steel slabs having the target composition of B shown in Table 3 above
After heating to a temperature of 20 ° C., hot rolling was carried out by an ordinary method to obtain a hot rolled sheet having a plate thickness of 2.4 mm.

Of these coils, 15 are 11
After hot-rolled sheet annealing for 30 seconds at a temperature of 50 ° C, it is rapidly cooled in a mist at a cooling rate of 30 ° C / s and then 1.50 in a tandem rolling mill.
cold rolled to mm thickness, then dew point: 60 ℃, H ₂ : 50%,
In the rest of N ₂ atmosphere, an intermediate anneal of temperature: 1080 ℃, time: 60 s was performed, and it was rapidly cooled to 350 ℃ in a mist at a cooling rate of 40 ℃ / s, and then kept at a temperature of 350 ℃ for 20 s. , 80
After air cooling to a temperature of ℃, it was pickled.

Then, using a Zenzimer rolling machine,
Cold rolling was carried out in the temperature range of 240 ° C. to a final plate thickness of 0.22 mm. In order to evaluate the permeability or coercive force after the final cold rolling, a sample was cut from a steel sheet and the maximum magnetizing force was set to 1000 with the hysteresis loss having a strong correlation with these magnetic properties.
It was set to A / m and measured.

Of these, four coils have a temperature of 10 ° C / 845 ° C.
Temperature: 845 ° C, time: 120s, dew point: 60 at s heating rate
℃, H ₂ : 50%, balance N ₂ atmosphere, decarburization, primary recrystallization annealing, MgO as a main component, TiO ₂ : 8%, Sr (OH) ₂ ·
An annealing separator containing 8H ₂ O: 3% and Fe ₂ O ₃ : 3% was applied to the steel sheet surface (both sides) at 12 g / m ² and wound into a coil.

Then, after heating in an N ₂ atmosphere to a temperature of 845 ° C. at a temperature rising rate of 40 ° C./h and holding at a temperature of 845 ° C. for 35 hours, N ₂ : 30%, H ₂ : 70% In the atmosphere of 1150 ℃
At a temperature rise rate of 15 ℃ / h to 1160 ℃
Then, the final annealing was performed by heating the temperature to 1160 ° C. and holding it in H ₂ at a temperature of 1160 ° C. for 8 hours.

Then, after removing the unreacted separating agent, a tension coating agent was applied also for flattening annealing, and baked in a N ₂ atmosphere at a temperature of 800 ° C. for a time of 90 s to obtain a product ( Comparative example).

On the other hand, for the remaining 4 coils after the final cold rolling, a sample was taken from a part of the coil and the same treatment as the comparative material was carried out in the laboratory to obtain the final coil of the coil having the best magnetic characteristics. The properties after cold rolling are: coercive force: 544 A / m, magnetic permeability: 0.551 × 10 ^-3 H / m, and hysteresis loss: 6.07 W / kg, which has a strong correlation with both coercive force and magnetic permeability. Obtained.

Therefore, the target value of hysteresis loss is 6.07.
Depending on the deviation of W / kg, decarburization of the remaining 3 coils
After changing the temperature rising rate from 500 ℃ to 800 ℃ after primary recrystallization annealing, other decarburization / primary recrystallization annealing, annealing separation material coating, final finishing annealing, tension coating coating, flattening annealing, etc. The conditions were the same as those of the comparative example (compatible example).

Table 6 shows the magnetic properties of the products of the comparative examples and the conforming examples, and the average values and standard deviations of the coercive force, magnetic permeability and hysteresis loss of the intermediate process products.

[0135]

[Table 6]

As is clear from Table 6, in comparison with the comparative example,
The magnetic properties of the conforming example of the present invention are significantly improved, and in addition to the coercive force of the steel sheet after the final cold rolling and the magnetic permeability, the method of the present invention for controlling the hysteresis loss depending on these to a target value is excellent. It indicates that

[0137]

The present invention relates to a method for producing a grain-oriented silicon steel sheet using the coercive force, magnetic permeability or hysteresis loss of the steel sheet after final cold rolling and before primary recrystallization annealing as an index.
According to the present invention, a grain-oriented silicon steel sheet having stable and excellent magnetic properties is obtained, which is advantageous in terms of quality assurance as well as improvement in yield, and the steel sheet obtained by the present invention is used as an iron core material for a transformer or the like. It can be applied very advantageously.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the average primary recrystallized grain size of a steel sheet after primary recrystallization annealing and various properties of a steel sheet after final finish annealing.

FIG. 2 is a graph showing the relationship between the coercive force of the steel sheet after final cold rolling and various characteristics of the steel sheet after final finish annealing.

FIG. 3 is a graph showing the relationship between the magnetic permeability of the steel sheet after final cold rolling and various characteristics of the steel sheet after final finish annealing.

Claims (9)

[Claims] 1. A silicon steel slab is heated, then hot-rolled, cold-rolled once or twice with an intermediate anneal, followed by decarburization / primary recrystallization annealing, and then annealing. In a method for producing a grain-oriented silicon steel sheet which is subjected to a final finishing annealing consisting of a secondary recrystallization annealing and a purification annealing by applying a separating agent, a coercive force of the steel sheet after the final cold rolling and before the start of the primary recrystallization, A method for producing a grain-oriented silicon steel sheet having excellent magnetic properties, characterized by controlling magnetic permeability or hysteresis loss within a predetermined range. 2. The magnetic device according to claim 1, wherein the control means is at least one selected from adjustment of slab heating conditions, adjustment of hot rolling conditions, and adjustment of cold rolling conditions including intermediate annealing. A method for producing a grain-oriented silicon steel sheet having excellent characteristics. 3. A silicon steel slab is heated, then hot-rolled, cold-rolled once or twice with an intermediate anneal, followed by decarburization / primary recrystallization annealing, and then annealing. In a method for producing a grain-oriented silicon steel sheet, which comprises applying a separating agent and performing a final finishing annealing consisting of secondary recrystallization annealing and purification annealing, a coercive force of the steel sheet after final cold rolling and before primary recrystallization annealing, Magnetic permeability or hysteresis loss is measured, and the measured value,
Depending on the deviation from the target value of coercive force, magnetic permeability or hysteresis loss, the primary recrystallization annealing conditions are adjusted, the coating amount and composition of the annealing separator are adjusted, and the secondary recrystallization annealing conditions are adjusted. A method for producing a grain-oriented silicon steel sheet having excellent magnetic properties, characterized by performing at least one selected treatment. 4. A silicon steel slab is heated, then hot-rolled, cold-rolled once or twice with intermediate annealing, followed by decarburization / primary recrystallization annealing, and then annealing. In a method for producing a grain-oriented silicon steel sheet which is subjected to a final finish annealing consisting of a secondary recrystallization annealing and a purification annealing by applying a separating agent, a coercive force of the steel sheet after the final cold rolling and before the primary recrystallization is After permeability or hysteresis loss and primary recrystallization,
A method for manufacturing a grain-oriented silicon steel sheet having excellent magnetic properties, which comprises controlling the coercive force of the steel sheet before the start of secondary recrystallization within a predetermined range. 5. The control means according to claim 4, wherein the steel plate after the final cold rolling and before the start of primary recrystallization is cold rolling including adjustment of slab heating conditions, hot rolling conditions and intermediate annealing. At least one selected from the adjustment of conditions, which is a steel plate after primary recrystallization and before the start of secondary recrystallization,
Directionality with excellent magnetic properties, which is at least one selected from adjustment of slab heating conditions, adjustment of hot rolling conditions, adjustment of cold rolling conditions including intermediate annealing, and adjustment of primary recrystallization annealing conditions Manufacturing method of silicon steel sheet. 6. A silicon steel slab is heated and then hot-rolled, and cold-rolled once or at least twice with intermediate annealing, followed by decarburization / primary recrystallization annealing, and then annealing. In a method for producing a grain-oriented silicon steel sheet, which comprises applying a separating agent and performing a final finishing annealing consisting of secondary recrystallization annealing and purification annealing, a coercive force of the steel sheet after final cold rolling and before primary recrystallization annealing, The permeability or hysteresis loss is measured, and the secondary recrystallization annealing conditions are adjusted according to the deviation between the measured value and the target value of coercive force, permeability or hysteresis loss, and the amount and composition of the composition of the annealing separator are applied. At least one treatment selected from the adjustment of the above and the adjustment of the primary recrystallization annealing condition, the coercive force of the steel sheet after the primary recrystallization annealing and before the secondary recrystallization annealing is measured, and the measurement is performed. 1 according to the deviation between the target value and the coercive force target value Magnetic properties characterized by performing at least one treatment selected from adjustment of recrystallization annealing conditions, adjustment of application amount and composition of annealing separator, and adjustment of secondary recrystallization annealing conditions. A method for manufacturing an excellent grain-oriented silicon steel sheet. 7. A silicon steel slab is heated and then hot-rolled, and cold-rolled once or twice or more with an intermediate anneal, followed by decarburization and primary recrystallization annealing, and then annealing. In a method for producing a grain-oriented silicon steel sheet, which comprises applying a separating agent and performing a final finishing annealing consisting of secondary recrystallization annealing and purification annealing, a coercive force of the steel sheet after final cold rolling and before primary recrystallization annealing, Magnetic permeability or hysteresis loss is measured, and the measured value,
After adjusting the primary recrystallization conditions according to the deviation from the target value of coercive force, permeability or hysteresis loss, the coercive force of the steel sheet after the primary recrystallization annealing and before the secondary recrystallization annealing is further adjusted. At least one treatment selected from the adjustment of the coating amount and composition of the annealing separator and the adjustment of the secondary recrystallization annealing condition according to the deviation between the measured value and the target value of the coercive force. A method for manufacturing a grain-oriented silicon steel sheet having excellent magnetic properties, characterized by: 8. The coercive force, magnetic permeability or hysteresis loss is obtained by online measurement.
2. A method for producing a grain-oriented silicon steel sheet having excellent magnetic properties according to 2, 4, or 5. 9. The method for producing a grain-oriented silicon steel sheet having excellent magnetic properties according to claim 3, 6 or 7, wherein the measurement of the coercive force, the magnetic permeability or the hysteresis loss is performed by online measurement.