JPH0663033B2 - Manufacturing method of thin grain-oriented silicon steel sheet with little iron loss deterioration - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for producing a thin grain-oriented silicon steel sheet having a plate thickness of 0.10 to 0.25 mm, and particularly to the amount of titanium compound in the annealing separator and the final finish. The present invention relates to a method for manufacturing a thin grain-oriented silicon steel sheet with less iron loss deterioration by limiting the cooling rate during annealing.

< _Prior Art> Conventionally, _grain- oriented silicon steel sheets have been mainly used as iron core materials for transformers and other electrical equipment, and have excellent magnetic properties, especially iron loss represented by W _17/50. Low characteristics are required. If this iron loss is large, the energy loss is large, and it is wastefully dissipated as heat. Therefore, from the viewpoint of energy saving, the demand for an iron core material having a low iron loss in which the loss is reduced is increasing year by year. By the way, the iron loss mainly consists of eddy current loss and hysteresis loss, but in the recent high magnetic flux density unidirectional silicon steel sheet, the loss due to eddy current accounts for 70% of the whole, which is effective in reducing the iron loss. Is most effective in reducing eddy current loss.

As one method of reducing this eddy current loss, it is effective to increase the electrical resistance in the silicon steel sheet.In the current manufacturing process, the Si content is increased to the extent that the silicon steel sheet can be processed. To increase the electrical resistance, or to process the product sheet to a very thin thickness (a steel sheet treated in this way is called thin grain oriented silicon steel sheet) and then increase the electrical resistance. Has been done.

Of these, the method of reducing the plate thickness of the product is considered to be the most advantageous and simple in terms of iron loss reduction, and in fact, products with a thickness of 0.35 mm and 0.30 mm have been used in many cases. Today, from the viewpoint of energy saving, 0.23mm, 0.20mm
Thick products have been widely used, and further, products with a small iron loss of 0.18 mm and 0.15 mm and low iron loss have been demanded.

Such a thin grain-oriented silicon steel sheet is mostly used for a small inner iron type iron core called a wound core due to restrictions in handling the steel sheet and manufacturing costs. This wound core is
In the deformation process during manufacturing, strain is generated by receiving a mechanical external force, and the magnetic characteristics are deteriorated. Therefore, in order to recover this strain, it is generally inevitable to perform strain relief annealing at about 800 ° C.

<Problems to be Solved by the Invention> However, even after the strain relief annealing, the iron loss often did not recover to the characteristics of the material before processing. Regarding iron loss deterioration during strain relief annealing, see
As described in JP-A-61-31164, a 0.30 mm-thick unidirectional silicon steel sheet coated with a phosphate-based coating is used to remove S, which has been removed from the steel in the purification step of final annealing.
Since Se reprecipitates in the steel during the stress relief annealing to deteriorate the iron loss, there is a method of minimizing the iron loss deterioration by lowering the stress relief annealing temperature according to the S and Se contents. It is disclosed.

However, in the thin grain-oriented silicon steel sheet of 0.10 to 0.25 mm, which has a thinner sheet thickness, the iron loss deterioration width in the strain relief annealing is very large, and even if the annealing temperature is lowered, deterioration does not improve at all. This is the reason why this deterioration cannot maximize the material characteristics of the transformer, and there is a big problem that the advantage of improving the iron loss due to the thinner plate thickness is offset.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a thin grain-oriented silicon steel sheet with less iron loss deterioration due to strain relief annealing.

<Means for Solving Problems> The present invention uses MnS, MnSe, A as an inhibitor of primary recrystallization.
The hot-rolled grain-oriented silicon steel sheet containing at least one of 1N and BN is cold-rolled once or twice or more with intermediate annealing to a thickness of 0.10 to 0.25 mm, and then decarburized and annealed. By applying an annealing separator containing a titanium compound and then performing final finishing annealing, in producing a thin grain-oriented silicon steel sheet, and a titanium compound adhesion amount when applying the annealing separator and A method for manufacturing a thin grain-oriented silicon steel sheet with less iron loss deterioration, characterized in that the relationship with the cooling rate during the final finish annealing is set as follows.

X ≧ 0.020 X ・ Y ≦ 3.0 where X: Ti on both sides per 1 m ² of steel plate of titanium compound
Converted adhesion amount (g / m ² ) Y: Cooling rate (° C / h) during final finish annealing.

<Operation> The inventors of the present invention have made extensive studies and investigations in order to find out the cause of iron loss deterioration due to strain relief annealing of a thin grain-oriented silicon steel sheet subjected to work strain. As a result, among the compounds added or mixed in the annealing separator, Ti compounds such as TiO ₂ decomposed during the final finish annealing and penetrated into the steel, and as TiN, TiC, etc. during cooling after the purification annealing. , It was discovered that a large number were finely precipitated in the steel. These fine precipitates impede the movement of dislocations, making it difficult to recover the work strain due to strain relief annealing, and also serve as suitable reprecipitation sites for the inhibitors returned to the steel during strain relief annealing, thus causing iron loss in the core. It was found that the characteristics were deteriorated.

By the way, these titanium compounds have been conventionally used as disclosed in Japanese Patent Publication No. 25-2858, Japanese Patent Publication No. 51-12451, Japanese Patent Publication No. 50-145315, or Japanese Patent Publication No. 59-185781. It is added for the purpose of stably forming a forsterite insulating film on a silicon carbide steel plate.

Although it is clear that iron loss deterioration can be reduced by reducing the amount of Ti in the annealing separator, the present inventors, in the case of a steel plate having a thin plate thickness, add to the insulating film when the steel plate is bent. As a result of studying that the stress is small, the plate thickness is 0.25 mm.
In the case of the following thin grain-oriented silicon steel sheets, it has been found that the Ti compound amount added to the annealing separator can secure the film characteristics even if it is much smaller than the amount conventionally required. In addition, the present inventors have found that the cooling rate from the purification annealing in the latter half of the final annealing has a great influence on the precipitation size of fine precipitates such as TiN and TiC, and the precipitates are grown by Ostwald and the number of particles is increased. Experiments were carried out paying attention to the fact that the effect on dislocation movement is drastically reduced by decreasing. As a result, they have found that when the product of the amount of titanium deposited and the cooling rate is a certain amount or less, it is possible to suppress the core loss of the core to a negligible level while securing the film characteristics.

Hereinafter, the present invention will be described in more detail.

For the starting material of the present invention, a conventionally known steelmaking method, for example, a converter, using a conventionally known unidirectional silicon steel material component,
Manufactured in an electric furnace, etc., and further made into a slab by the ingot-segmentation method, continuous casting method, etc.
After heating at a high temperature of 50 ° C to dissociate and solidify the inhibitor,
A hot rolled sheet having a thickness of 1.0 to 3.5 mm by hot rolling may be used. This hot-rolled sheet preferably has a composition containing Si of about 2.0 to 4.0%. This is because if the Si content is less than 2%, the iron loss deteriorates significantly, and if it exceeds 4%, the cold workability deteriorates. Regarding the other components, any of the directional silicon steel material components can be applied,
As an inhibitor for developing the secondary recrystallization strongly integrated in the Goss orientation, it is optimal to include one or more selected from MnS, MnSe, AlN, BN, etc. in the steel within a known range. Next, this hot-rolled sheet was cold-rolled once or twice with intermediate annealing, and the sheet thickness was 0.22 mm.
Three levels of 0.17 mm and 0.12 mm test materials were prepared. Here, the plate thickness is 0.10 for thin grain-oriented silicon steel plates.
The range is ~ 0.25 mm. Then, these test materials were subjected to primary recrystallization annealing in a dehydrocarburizable wet hydrogen atmosphere at 750 ° C, and then MgO added with TiO ₂ as an annealing separator.
The slurry was applied. The amount of Ti deposited on both sides of the test material is 1
5 mg, 10 mg, 20 mg, 30 mg, 50 mg, 100 mg, 200 per m ²
8 levels of mg and 300 mg were adjusted. Next, finish purification annealing, cooling rate after purification annealing is 20 ℃ / h, 30 ℃
/ H, 50 ° C / h and 100 ° C / h. After that, a glass coating film was coated to make the product plate thicknesses of the test materials 0.23 mm, 0.18 mm, and 0.13 mm, respectively, and then the bending adhesion of the insulating film was examined. The survey results are shown in FIG. As is clear from this figure, in the region where the amount of Ti deposited per 1 m ² is less than 20 mg, the bending adhesion is significantly deteriorated, but there is no difference due to the cooling rate.

Next, for the sample material with a plate thickness of 0.17 mm, after subjecting it to the product plate thickness of 0.18 mm by the same treatment as above, iron loss deterioration before and after strain relief annealing at 800 ° C for 5 hours in a nitrogen stream Quantity ΔW _17/50
investigated. The results are shown in FIG. In the figure, when the iron loss is deteriorated by the strain relief annealing, it takes a positive value. Also, as is clear from the figure, in order to make the iron loss deterioration due to strain relief annealing negligible (about 0.01 W / kg), the Ti deposition amount is 100 mg / m ² or less and the cooling rate is 30 ° C.
It turns out that it is necessary to be less than / h.

FIG. 3 is a characteristic diagram in which the relationship between the amount of Ti deposited and the cooling rate during the above experiment using the test material having a plate thickness of 0.17 mm was investigated. In the figure, ○ indicates good characteristics (deterioration of iron loss is 0.
01W / kg or less), ● indicates large iron loss deterioration, Indicates a film defect. As is clear from this figure, in order to make the iron loss deterioration due to the strain relief annealing negligible (about 0.01 W / kg), the amount of Ti deposited is X (g / m ² ) and the cooling rate is Y. It can be seen that it is necessary to satisfy X · Y ≦ 3.0 (region on the left side of the straight line in FIG. 3) when (° C./h). Also,
It is also understood that the Ti adhesion amount X needs to be 20 mg or more.

Now, considering the above characteristics, the following can be said. First, the lower limit of the Ti adhesion amount X is necessary for stable formation of the forsterite film, and it is considered that if the amount is less than 0.020, the adhesion of the film is significantly impaired. On the other hand, when the product of the Ti deposition amount X and the cooling rate Y exceeds 3.0, that is, when the cooling rate is higher than the Ti deposition amount, it penetrates into the steel and forms a solid solution during the purification annealing. However, since it cannot grow after being precipitated as TiN or TiC during cooling, many fine precipitates are dispersed. It is considered that these not only deteriorate the magnetic properties as impurities, but also hinder the movement of dislocations, which makes it difficult to recover the work strain by strain relief annealing, and the iron loss is considered to deteriorate. If the product of X and Y is 3.0 or less, Ti
Although the increase in the amount of adhesion does not affect the magnetism, it takes a long time for cooling, which is not economically preferable.

<Examples> Examples of the present invention will be described below.

% By weight, C: 0.073%, Si: 3.25%, Mn: 0.068%, A
l: 0.030%, S: 0.024%, N: 0.0080% After heating the silicon steel slab consisting of the balance Fe to 1300 ° C, the plate thickness is 2.3 mm.
It was hot rolled to. The hot rolled sheet was cold rolled to 1.35 mm. Then, after annealing at 1120 ° C. for 4 minutes, cold rolling was performed to finish the plate thickness to 0.17 mm. Continue to 840
After applying decarburization annealing in a wet hydrogen atmosphere at ℃ for 3 minutes and applying an annealing separator with MgO as the main component, divide into two equal parts in MgO.
After adding iO ₂ , the amount of Ti adhered per 1 m ² both sides of the steel sheet after applying MgO was adjusted to be 0 mg, 50 mg, and 200 mg. After drying, finish annealing was performed at 1200 ° C. for 20 hours. After annealing at 1200 ℃, cooling the steel plate is divided into two equal parts, 30 ℃ / h and 100 ℃ / h.
I took the standard. The steel sheet thus prepared is coated with colloidal silica, aluminum phosphate, and chromic anhydride-based coating treatment liquid so as to have a film thickness of 2 μm on one side.
Baking in N ₂ at 800 ° C. for 1 minute. Subsequently, strain relief annealing was performed at 850 ° C for 5 hours, and iron loss W _{17/50 was measured} before and after the strain relief annealing.
Was measured and compared. In addition, the bending adhesion of the insulating film was measured.

Table 1 shows the iron loss deterioration before and after the stress relief annealing as ΔW.

As is clear from this table, steel plate N that falls within the scope of the present invention
It is understood that o.3 is excellent in iron loss deterioration amount ΔW and bending adhesion.

<Effects of the Invention> As described above, according to the present invention, the relationship between the titanium compound contained in the annealing separator applied before the final finish annealing step and the cooling rate during the final finish annealing is defined. Therefore, it becomes possible to manufacture a thin grain-oriented silicon steel sheet with less iron loss deterioration due to strain relief annealing, and the effect of energy saving is great.

[Brief description of drawings]

Fig. 1 is a characteristic diagram showing the influence of the Ti deposition amount on bending adhesion by product thickness, and Fig. 2 is the Ti deposition amount on iron loss deterioration of 0.18 mm thick product sheet due to stress relief annealing. FIG. 3 is a characteristic diagram showing the influence, and FIG. 3 is a characteristic diagram showing the influence of the Ti deposition amount on the cooling rate after the purification annealing of the 0.18 mm thick product plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Bunjiro Fukuda 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Headquarters (72) Inventor Yasuo Yokoyama 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Co., Ltd. Technical Research Division

Claims (1)

[Claims] 1. An inhibitor of primary recrystallization, which comprises MnS, MnSe,
Hot-rolled grain-oriented silicon steel containing at least one of AN and BN is cold-rolled once or twice or more with intermediate annealing to obtain a sheet thickness of 0.10 to 0.25 mm, and then decarburized and annealed. By applying an annealing separator containing a titanium compound and then performing final finishing annealing, in producing a thin grain-oriented silicon steel sheet, and a titanium compound adhesion amount when applying the annealing separator and A method for manufacturing a thin grain-oriented silicon steel sheet with less iron loss deterioration, characterized in that the relationship with the cooling rate during the final finish annealing is set as follows. X ≧ 0.020 X ・ Y ≦ 3.0 where X: Ti on both sides per 1 m ² of steel plate of titanium compound
Converted adhesion amount (g / m ² ) Y; Cooling rate (° C / h) during final finish annealing