JPH09241754A - Production of grain oriented silicon steel sheet, and coating device for separation agent at annealing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a grain oriented silicon steel sheet having uniform magnetic properties and film characteristics over the entire length of the steel sheet by changing the additive quantity of a film formation accelerator, to be added to a separation agent at annealing, depending on the position of coiling. SOLUTION: A silicon-containing slab is hot-rolled, formed into final sheet thickness by cold rolling including process annealing between cold rolling stages, and then subjected to decarburizing and primary recrystallization annealing. After a separation agent at annealing, containing a film formation accelerator, is applied, the resultant sheet is coiled and then subjected to finish annealing consisting of secondary recrystallization annealing and purification annealing, by which the grain oriented silicon steel sheet is produced. At this time, the additive quantity of the film formation accelerator added to the separation agent at annealing, to be applied to the surface of the steel sheet, is changed depending on the coiling position in the longitudinal direction of the steel sheet. For example the additive quantity of the film formation is increased in the outer part and inner part of coil than the intermediate part of coil. It is preferable to add 5-10wt.% in the outer part and inner part of coil, 1-5wt.% in the intermediate part of coil. The film formation accelerator is one or more kinds among TiO2 , CuO and CaO.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a grain-oriented silicon steel sheet having uniform magnetic properties and coating properties over the entire length of the steel sheet, and an annealing separator coating device.

In the manufacturing process of grain-oriented silicon steel sheets, it is indispensable to wind them into a coil and subject them to secondary recrystallization by finishing annealing consisting of secondary recrystallization annealing at high temperature for a long time and purification annealing. is there. At that time, in order to prevent seizure between steel sheets due to high temperature annealing, MgO was added in the pre-process of finish annealing.
An annealing separator having as a main component is applied to the surface of the steel sheet. This annealing separator is used by dispersing MgO in water to form a slurry, which is evenly applied to the surface of a steel sheet with a grooved roll (roll coater).

MgO applied to the surface of the steel sheet as an annealing separating agent forms a forsterite insulating coating by the reaction shown in the following formula by finish annealing.
Furthermore, this insulating coating has the effect of imparting tension to the steel sheet and improving iron loss. SiO ₂ + 2MgO → Mg ₂ SiO ₄

[0004]

2. Description of the Related Art In the annealing of steel sheets, a continuous annealing method is suitable for ensuring uniformity over the entire length of the steel sheet. However, finish annealing of grain-oriented silicon steel sheet requires high temperature and long time. Therefore, a method of winding a steel sheet into a coil and annealing the coil in a batch furnace is used.

Therefore, a difference in temperature rising rate occurs between the inner winding portion and the outer winding portion of the coil and the middle winding portion, and therefore the forsterite insulating coating formed during the finish annealing also
As shown in the explanatory view showing the non-uniform portion of the insulating coating when finish annealing is performed in the coil shape in FIG. 1, quality unevenness occurs in each winding portion of the coil, that is, in the steel plate longitudinal direction. It is known that the deterioration of the coating film characteristics of the coil outer winding portion and the inner winding portion due to the unevenness of quality is reduced by the addition or increase of the addition amount of the film formation accelerator to the annealing separator.

However, if the amount of the film formation accelerator added is increased too much, there is a problem that the magnetic characteristics of the coil middle winding portion are deteriorated.

On the other hand, the annealing separator is usually used by adding a few percent of the film formation accelerator to MgO in order to accelerate the formation of the forsterite insulating coating. The powdery state MgO and the film-forming accelerator were weighed and mixed, water was added, and the mixture was stirred with a mixer to obtain an annealing separator slurry, which was supplied to the surface of the steel sheet for coating. Therefore, it was impossible to change the concentration of the film formation promoter in the slurry depending on the longitudinal direction of the steel sheet, that is, the coil winding position.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems in an advantageous manner, and devises an annealing separator applied to the surface of a steel sheet to obtain uniform magnetic properties and coating over the entire length of the steel sheet. It is an object of the present invention to propose a method for producing a grain-oriented silicon steel sheet having characteristics and an annealing separator application device for the same.

[0009]

As a result of various investigations, the inventor has found that it is optimal to change the composition of the annealing separator depending on the position of the coil to obtain a product of uniform quality over the entire length of the steel sheet. The inventors have found out that there is something and achieved the present invention. That is, the gist of the present invention is as follows.

After heating the silicon steel slab, it is hot-rolled and then cold-rolled once or twice with an intermediate anneal to finish it to the final thickness, followed by decarburization and primary recrystallization annealing. Then, after applying an annealing separator containing a film formation accelerator to the surface of the steel sheet, winding the coil on a coil, and finishing annealing such as secondary recrystallization annealing and purification annealing, Decarburization ・ 1 when manufacturing plain steel sheets
A method for producing a grain-oriented silicon steel sheet, characterized in that the addition amount of the film formation promoter added to the annealing separator applied to the steel sheet surface after the secondary recrystallization annealing is changed depending on the coil winding position in the steel sheet longitudinal direction ( First invention).

The method for producing a grain-oriented silicon steel sheet according to the first aspect of the present invention is characterized in that the amount of the film formation accelerator added is larger in the outer winding portion and the inner winding portion than in the middle winding portion of the coil. (Second invention).

A first feature of the present invention is that the film formation accelerator is added in an amount of 5 wt% or more and 10 wt% or less in the outer winding portion and the inner winding portion of the coil and 1 wt% or more and less than 5 wt% in the middle winding portion. Alternatively, the method for producing a unidirectional silicon steel sheet according to the second invention (third invention).

The unidirectionality according to the first, second or third invention, wherein the film formation accelerator is one or more selected from TiO ₂ , CuO and CaO. Method for manufacturing silicon steel sheet (fourth invention).

After heating the silicon steel containing slab, it is hot-rolled and then cold-rolled once or twice with intermediate annealing to finish it to a final plate thickness, and then decarburization / primary recrystallization annealing. After that, the annealing separation agent containing a film formation accelerator is applied to the surface of the steel sheet, the coil is wound up into a coil, and then a secondary recrystallization annealing / purification annealing finish annealing is performed. A roll coater type annealing separator coating device for manufacturing a steel sheet, wherein the annealing separator coating device has an annealing separator spray manufacturing device and a film formation accelerator additional injection device, and an annealing separator slurry is provided. Annealing separation that connects the passage of the film formation accelerator from the film formation accelerator additional injection device to the slurry passage from the slurry supply pump of the manufacturing equipment to the slurry supply nozzle that supplies the annealing separation agent slurry to the steel plate surface Agent coating device (Fifth invention).

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The operation and effect of the present invention will be described below with reference to experimental examples.

First, the results of investigations on the effect of the film formation accelerator in the annealing separator on the insulating film characteristics and iron loss are described below. The relationship between the amount of film formation promoter added to the annealing separator, the film adhesion (minimum bending diameter at which the film does not peel off) and the film nonuniform part length in the outer and inner winding parts of the coil after finish annealing is shown. As shown in Table 1, as is clear from Table 1, as the amount of the film formation promoter added increases, the film adhesion improves and the film nonuniform portion length also becomes shorter.

[0017]

[Table 1]

On the other hand, a graph of the iron loss in the longitudinal direction (excluding the non-uniform coating portion of the outer and inner winding parts of the coil) of each coil, that is, the amount of the film formation accelerator added, is shown in FIG. As shown in FIG. As is clear from this figure, the core loss decreases as the amount of the film formation promoter added decreases in the middle coil portion, and the D sample with the minimum amount of addition (3 wt%) exhibits the best iron loss. .

The present invention is based on the results of such investigations. In order to obtain a uniform coating property and magnetic property in the lengthwise direction of a steel sheet, a steel sheet (primary recrystallization annealed sheet) is manufactured. Change the amount of film formation promoter added to the applied annealing separator depending on the coil winding position, and further add the amount of film formation promoter in the outer and middle winding parts compared to the middle winding part of the coil. It is necessary to increase the amount of the film formation promoter added to the outer winding portion and inner winding portion of the coil at 5 wt% or more and 10 wt% or less, and the middle winding portion of 1 wt% or more and less than 5 wt%. is important.

In the outer winding portion and the inner winding portion of the coil, the effect of improving the film formation is not sufficient when the amount of the film formation promoter added is less than 5 wt%, and the magnetic properties deteriorate when it exceeds 10 wt%. In the middle winding portion, if the addition amount is less than 1 wt%, the film formation failure occurs, and if it is 5 wt% or more, the magnetic characteristics deteriorate.

As the film formation accelerator, generally known TiO ₂ , CuO, CaO and the like may be used alone or in combination.

Here, the reason why the amount of the film formation accelerator added to the annealing separator applied to the primary recrystallization annealed plate is larger in the outer winding portion and the inner winding portion than in the middle winding portion of the coil, That is, the film formation mechanism during batch annealing of a steel sheet coated with an annealing separator and wound into a coil will be described below. When the temperature of the coil is increased by heating, as shown in the graph of the temperature distribution in the coil cross section shown in FIG. 3 and the graph of the relationship between temperature and time at the middle winding part (C / P: cold point) of the coil shown in FIG. The winding part and the inner winding part are
Temperature rises 10 to 100 ° C / h faster. Therefore, the SiO ₂ levitation reaction in the subscale of the steel sheet is too fast in the outer and inner winding portions, and the adhesion of the coating of (a) in the explanatory view of the cross-sectional structure of the forsterite insulating coating in FIG. As in the case of deterioration, the base iron-coating interface becomes smooth, and in some cases, the coating may fall off to expose the base iron. Therefore, if an appropriate amount of film formation accelerator is added to the annealing separator,
Before the floating reaction of SiO ₂ proceeds too much, the reaction between MgO and SiO ₂ proceeds and is fixed as a forsterite insulating coating, as in the case where the adhesion of the coating shown in Fig. 5 (b) is good. The structure is like rooting on the ground iron. In the above, the appropriate amount of the film formation promoter added increases as the heating rate increases.

On the other hand, in the middle winding part of the coil, when the film formation accelerator is added excessively, deterioration of iron loss (hysteresis loss) due to intrusion of Ti or the like used as a film formation accelerator into the base iron, SO Deterioration of iron loss (eddy current loss) etc. occurs due to coarsening of secondary recrystallized grains due to ₄ roots. For this reason, the upper limit value of the amount of the film formation accelerator added for preventing the deterioration of the magnetic properties is smaller in the middle winding portion than in the outer winding portion and the inner winding portion of the coil.

The phenomenon described above is large between the layers of the tightly wound coil, the rate of temperature rise is high at the time of temperature rise, and the thermal expansion is large correspondingly, so that the winding is somewhat loose (C
・ It is smaller at the outer winding than P).

From the above, by appropriately changing the addition amount of the film formation accelerator in the longitudinal direction of the steel sheet and applying the annealing separator, the film characteristics and the magnetic characteristics can be improved without being affected by the coil winding position. A grain-oriented silicon steel sheet that is uniform in the length direction is manufactured.

Next, a description will be given of the suitable component composition range and suitable manufacturing process of the silicon steel material which is the object of the present invention.

Component composition range The component composition of a usual material for grain-oriented silicon steel sheet may be used, and the preferable range thereof is as follows.

C: 0.10 wt% or less C is a component useful not only for making the structure uniform and fine during hot rolling and cold rolling but also for developing the Goss orientation, but 0.10 wt%
If it is contained in excess of 0.1%, decarburization becomes difficult, and the Goss orientation is disturbed, so the content should be 0.10 wt% or less. The lower limit is preferably 0.01 wt%.

Si: 2.5-4.5 wt% Si increases the specific resistance of the steel sheet and effectively contributes to the reduction of iron loss, but if the content exceeds 4.5 wt%, the cold rollability is impaired, while 2.5 wt% If the content is less than 100%, not only the specific resistance decreases, but also the crystal orientation is randomized by α-γ transformation during the secondary recrystallization and final finishing annealing performed for purification, and a sufficient iron loss reducing effect is obtained. You won't get it. Therefore, its content is preferably in the range of 2.5 to 4.5 wt%.

Mn: 0.15 wt% or less Mn is at least 0.04 wt% in order to prevent hot embrittlement.
%, The upper limit of the content is 0.15 wt% because if it is contained excessively, the magnetic properties deteriorate.
It is good to set it as%.

When using MnS and MnSe as inhibitors. At least one selected from S and Se: 0.005 to 0.
06wt% S, Se is an important component as an inhibitor-forming component that controls secondary recrystallization of grain-oriented silicon steel sheet. From the viewpoint of suppressing power, at least 0.005 wt% is preferably contained, and if it exceeds 0.06 wt%, the effect is impaired. Therefore, their content is 0.005 ~
It is preferably in the range of 0.06 wt%.

When using AlN 3 as an inhibitor. Al: 0.005 to 0.10 wt%, N: 0.004 to 0.015 wt% Al and N content ranges are preferably set to the above ranges for the same reason as in the case of MnS and MnSe.

As the inhibitor, the above-mentioned Mn is used.
One or more selected from S, MnSe and AlN can be used in combination. As the inhibitor component, in addition to S, Se and Al described above, Cu,
Since Sn, Sb, Mo, Ti, Bi and the like also have an advantageous effect, they can be contained in a small amount. The preferred range of the content of these components is 0.01 to 0.15 wt% for Cu and Sn, respectively.
%, Sb, Mo, Ti, Bi in the range of 0.005 to 0.1 wt%,
Each of these inhibitor components can also be used alone or in combination.

Manufacturing process: Molten steel obtained by a conventional steelmaking method and adjusted to the above-mentioned composition is made into a slab having a predetermined thickness by continuous casting or ingot-casting method, and then the inhibitor components Al, Se, and S are added. In order to form a complete solid solution, the material is heated and soaked to a temperature of 1200 ° C or higher by induction heating or the like. The slab after the heating-soaking is hot-rolled, and then hot-rolled sheet annealing for homogenizing the structure and stabilizing secondary recrystallization is performed as necessary.

Next, cold rolling is performed once or twice or more with an intermediate anneal between them to obtain a final plate thickness, and then decarburization / secondary recrystallization annealing is performed.

After that, in the present invention, it is important to apply the annealing separator by changing the addition amount of the film formation accelerator depending on the coil winding position in the longitudinal direction of the steel sheet as described above.

After the annealing separator is applied, the coil is wound and subjected to ordinary finish annealing (secondary recrystallization annealing / purification annealing) to obtain a grain-oriented silicon steel sheet.

By the way, according to the present invention, it is necessary to change the amount of the film formation accelerator added to the annealing separator in the longitudinal direction of the steel sheet in the continuous step of applying the annealing separator.

Therefore, as an annealing separator applying device for that purpose, an annealing separator slurry manufacturing device and a film formation accelerator additional injection device are provided, and the slurry is supplied to the steel plate surface from a slurry supply pump of the annealing separator slurry manufacturing device. The passage for the film formation accelerator from the film formation accelerator adding device is connected to the slurry passage leading to the slurry supply nozzle. By doing so, the annealing separator slurry to be supplied to the steel sheet can be added with the film formation accelerator immediately before the supply, and the amount of the film formation accelerator added to the annealing separator can be easily adjusted in the longitudinal direction of the moving steel sheet. You can change it.

As an example, FIG. 6 shows an explanatory view of an annealing separating agent coating apparatus which is suitable for the present invention.

In FIG. 6, 1 is an MgO hopper, 2 is a film formation accelerator hopper, 3 is a water absorption tank, 4 is an adjusting stirring tank, 5 is a slurry storage tank, 6 is a slurry supply pump,
Reference numeral 7 is a slurry supply nozzle, and 8 is a grooved roll for coating. Up to now, the annealing separator has been coated on the steel plate 12 with these configurations. In addition to these, the present invention is provided with a film formation accelerator additional supply tank 9 and an additional injection pump 10 to provide a passage 11 for the annealing separator slurry from the slurry supply pump 6 to the slurry supply nozzle 7. The passage of the film formation promoter from the additional infusion pump 10 is connected at the connection position of.

In FIG. 6, 13 is an apparatus for producing an annealing separation agent slurry, and 14 is an apparatus for additionally injecting a film formation accelerator, which is surrounded by a dotted line.

In the above structure, by adjusting the additional supply amount of the film formation accelerator from the additional injection pump 10,
The annealing separator, in which the amount of the film formation promoter added is controlled, can be supplied from the slurry supply nozzle 7 to the surface of the steel plate 12. For example, the process computer controls the additional supply timing and supply amount of the film formation accelerator,
That is, based on the information on the coil diameter of the winder (not shown), it may be possible to additionally supply a different amount of the film formation promoter depending on the position of the steel plate 12 in the longitudinal direction. It is possible to change the amount of the film formation promoter added therein according to the required amount that varies depending on the coil winding position in the longitudinal direction of the steel sheet.

[0044]

【Example】

C: 0.048 wt%, Si: 3.25 wt%, Mn: 0.081 wt%, S:
0.025 wt%, Se: 0.018 wt%, Sb: 0.025 wt% and M
o: 200 mm containing 0.019 wt% and the balance consisting essentially of Fe
After heating a thick continuous cast slab at a temperature of 1380 ° C for 1 hour,
Plate thickness: Hot rolled to 2.2 mm. Then the temperature: 930 ℃,
Time: 2 minutes of hot-rolled sheet annealing, followed by pickling, sheet thickness:
After intermediate rolling (cold rolling) to 0.65 mm, temperature: 980 ° C, time: 1.5 minutes of intermediate annealing, and final cold rolling with a reduction rate of 66% to finish the sheet thickness: 0.22 mm. .

Then, after degreasing, in wet H ₂ temperature: 840
After decarburization and primary recrystallization annealing for 3 minutes at ℃, time: Annealing agent mainly composed of MgO with different addition amount including type of film formation accelerator and longitudinal direction of steel sheet
It was applied at g / m ² (both sides).

In this case, according to the application example of the present invention, in order to ensure the uniformity of the film properties and magnetic properties of the product, it is necessary to increase the amount of the film formation accelerator added to the annealing separator. The length of the outer winding part and the length of the inner winding part and the amount added are obtained in advance and based on these values,
The annealing separator was applied with the annealing separator applying device having the structure shown in FIG.

After the annealing separator is applied, it is dried and wound on a coil, respectively, and then secondary recrystallization annealing is carried out in dry N ₂ at a temperature of 845 ° C. for 35 hours, followed by drying in dry H ₂ . Temperature: 1200 ° C., time: 10 hours for purification annealing.

Then, after removing the annealing separator, tension coating was applied and flattening annealing was performed to obtain respective products.

With respect to the outermost wound portion, the middle wound portion and the innermost wound portion of each product coil thus obtained, the magnetic characteristics, the adhesion of the coating and the length of the nonuniform portion of the coating were investigated. The survey results are summarized in Table 2.

[0050]

[Table 2]

As is clear from Table 2, all the conforming examples conforming to the present invention show that the magnetic characteristics are equally excellent in the outer winding part, the middle winding part and the inner winding part of the coil, and the adhesion of the coating film is good. The length of the non-uniform portion of the coating on the outer winding portion and the inner winding portion of the coil is stable and shows a short value.

On the other hand, among the comparative examples in which the amount of the film-forming accelerator added was substantially the same in the longitudinal direction of the coil, Sample Nos. 2, 5 and 8 in which the amount added was 2 to 4 wt% were wound on the outside of the coil. The adhesion of the coating is inferior in the inner part and the inner winding part, the length of the non-uniform part of the coating is long, and the addition amount is 6 to 9 wt%.
In Nos. 3, 6 and 9, the iron loss is deteriorated at the inner winding portion or the outer winding portion of the coil.

[0053]

The present invention is intended to change the amount of the film formation promoter added to the annealing separator in the production of grain-oriented silicon steel sheets depending on the coil winding position in the longitudinal direction of the steel sheet. According to this, quality deterioration of the forsterite insulating coating on the outer and inner winding parts of the coil can be prevented, uniform magnetic properties and coating properties can be obtained in the longitudinal direction of the steel sheet, the amount of waste is reduced, and the yield is improved. Can greatly contribute to

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a non-uniform portion of an insulating coating when finish annealing is performed in a coil shape.

FIG. 2 is a graph of iron loss in the longitudinal direction of each coil in which the amount of film formation accelerator added is changed.

FIG. 3 is a graph showing a temperature distribution of a coil cross section.

FIG. 4 is a graph showing a relationship between temperature and time in a coil middle winding portion.

FIG. 5 is an explanatory diagram of a cross-sectional structure of a forsterite insulating coating. (a) is when the adhesiveness is deteriorated. (b) is when the adhesion is good.

FIG. 6 is an explanatory view of an annealing separating agent applying device which is suitable for the present invention.

[Explanation of symbols]

 1 MgO hopper 2 Coating formation accelerator hopper 3 Water absorption tank 4 Adjustment stirring tank 5 Slurry storage tank 6 Slurry supply pump 7 Slurry supply nozzle 8 Grooved roll for coating 9 Tank for additional supply of coating formation accelerator 10 Pump for additional injection 11 Coupling position 12 Steel plate 13 Annealing agent slurry manufacturing device 14 Coating formation accelerator additional injection device

Claims (5)

[Claims] 1. A silicon steel-containing slab is heated and then hot-rolled, and then cold-rolled once or twice with intermediate annealing to finish to a final thickness, followed by decarburization and primary re-rolling. After performing crystal annealing, after applying an annealing separator containing a film formation accelerator to the surface of the steel sheet and winding it into a coil, the secondary recrystallization annealing / purification annealing finish annealing is performed. When manufacturing a silicon carbide steel sheet, change the amount of film formation promoter added to the annealing separator applied to the steel sheet surface after decarburization and primary recrystallization annealing, depending on the coil winding position in the longitudinal direction of the steel sheet. And a method for manufacturing a grain-oriented silicon steel sheet. 2. The grain-oriented silicon steel sheet according to claim 1, wherein the film formation accelerator is added in a larger amount in the outer winding portion and the inner winding portion than in the middle winding portion of the coil. Production method. 3. The addition amount of the film formation accelerator is 5 wt% or more and 10 wt% or less in the outer winding portion and the inner winding portion of the coil and 1 wt% or more and less than 5 wt% in the middle winding portion. The method for manufacturing a unidirectional silicon steel sheet according to claim 1. 4. The film formation accelerator comprises TiO ₂ , CuO and
The method for producing a unidirectional silicon steel sheet according to claim 1, 2 or 3, wherein any one or more selected from CaO. 5. A silicon steel-containing slab is heated, then hot-rolled, and then cold-rolled once or twice with intermediate annealing, to obtain a final plate thickness, followed by decarburization and primary re-rolling. A unidirectional process is carried out by a series of steps in which crystal annealing is performed, then an annealing separator containing a film formation accelerator is applied to the steel sheet surface, the coil is wound, and then finish annealing such as secondary recrystallization annealing and purification annealing is performed. A roll coater type annealing separator applying device for manufacturing silicon steel sheets, wherein the annealing separator applying device has an annealing separator slurry manufacturing device and a film formation accelerator additional injection device, and is subjected to annealing separation. The slurry passage from the slurry supply pump of the agent slurry manufacturing device to the slurry supply nozzle that supplies the annealing separator slurry to the steel plate surface is connected to the passage of the film formation accelerator from the additional film formation accelerator injection device. Annealing agent coating equipment .