JP3232148B2 - Manufacturing method of grain-oriented electrical steel sheet with excellent magnetic properties - Google Patents

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 unidirectional silicon steel sheet having excellent magnetic properties, which is mainly used as a core material for transformers and other electric equipment.

[0002]

2. Description of the Related Art As the iron core material of this kind of electric equipment,
Excellent magnetic properties, specifically 800A /
It is required that the magnetic flux density B ₈ (T) at m is high and the iron loss characteristic W _17/50 (W / kg) at an AC magnetic flux density of 1.7 T at 50 Hz is low. For this reason, oriented silicon steel sheets
The {110} <001> orientation, a so-called Goss orientation, is developed using secondary recrystallization. In order to obtain a material with excellent magnetic properties, the easy axis <001>
The axis must be highly aligned in the rolling direction, and it is important to stably develop the secondary recrystallized grains in the Goss orientation by various processes combining appropriate rolling and heat treatment.
In particular, it is important to uniformly and finely disperse a precipitate called an inhibitor such as AlN or MnS or MnSe.

To achieve this, Japanese Patent Publication No. 50-21291
Japanese Patent Laid-Open Publication No. H10-15064 discloses a method in which the finish front temperature during hot rolling is set to 1150 ° C. or lower to precipitate an inhibitor during finish rolling. In this method, a steel sheet is cooled to a temperature lower than the precipitation temperature of an inhibitor such as AlN or the like, and strain such as rolling is introduced into the steel sheet to precipitate an inhibitor such as AlN. However, in the above method, the surface layer is cooled before the finish rolling, so that there is a problem that the inhibitor (such as AlN) on the surface of the sheet surface is coarsely precipitated.

In Japanese Patent Publication No. 59-45730, AlN
This shows a method of controlling the precipitation of steel at a high temperature during hot rolling, but it is difficult to control the temperature uniformly in the longitudinal and width directions of the coil industrially, which is not practical. .

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to propose a manufacturing method capable of industrially stably obtaining a grain-oriented electrical steel sheet having excellent magnetic properties.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for producing S by weight%.
i: 2.0-4.5%, C: 0.01-0.12%, acid-soluble Al: 0.0
Hot-rolled steel containing 10 to 0.06%, N: 0.0030 to 0.0120%, and if necessary, 0.005 to 0.060% of one or two of S and Se in addition to 0.02 to 0.15% of Mn. Then, one or more times of cold rolling is performed to obtain a final sheet thickness, and then a series of steps of decarburizing annealing followed by final finishing annealing are performed. The side temperature is 1100 ° C or higher and 1250 ° C or lower, the finish-rolling outlet temperature is higher than 1050 ° C, and immediately after cooling, the winding temperature is set to 700 ° C or lower. And a weight ratio of SiO ₂ to 0.2 or less.

[0007]

The present inventors have intensively studied an inhibitor control method in order to obtain an electromagnetic steel sheet having excellent electromagnetic characteristics. As a result, the inhibitor thickness was reduced during hot rolling and oxidation during finish annealing was performed. It has been found that a means for suppressing the oxidative decomposition of the surface layer inhibitor due to a neutral atmosphere is very effective.

That is, as a means for refining the surface layer portion inhibitor during hot rolling, a method is effective in which strain is applied by finish rolling, then the sheet is cooled, and the inhibitor is precipitated at a stroke. For the surface oxidation of the inhibitor during annealing, it was found that a method of densifying the oxide film on the steel sheet surface during decarburizing annealing by increasing SiO ₂ was effective.

First, a preferred composition range of the electromagnetic steel sheet used in the present invention will be described. Si: 2.0-4.5% Si increases the specific resistance of the steel sheet and effectively contributes to the reduction of iron loss. However, when it exceeds 4.5%, the cold-rolling property is impaired, whereas when it is less than 2.0%, the specific resistance only decreases. Not secondary recrystallization
Since the crystal orientation is randomized by the α-γ transformation during the final high-temperature annealing performed for purification, and a sufficient iron loss improvement effect cannot be obtained, the Si content is preferably about 2.0 to 4.5%.

C: 0.01 to 0.12% C is an element useful not only for uniform micronization of the structure during hot rolling and cold rolling, but also for development of the Goss orientation.
The content is preferably 0.01% or more. However, if the content exceeds 0.12%, the Goss orientation is rather disturbed. Therefore, the upper limit is preferably about 0.12%.

Mn: 0.02 to 0.15% Mn needs to be at least about 0.02% in order to prevent hot embrittlement, but if it is too much, it deteriorates the magnetic properties. Therefore, the upper limit should be set to about 0.12%. preferable. Inhibitors include the following AlN-based inhibitors,
There are nS and MnSe systems.

First, in the case of AlN system, acid soluble Al: 0.01 to 0.06% N: 0.0030 to 0.0120% Al and N are effective elements as inhibitors for controlling secondary recrystallization of grain-oriented silicon steel sheets. From the viewpoint of securing the restraining force, at least 0.01% of Al and 0.0090% of N are required. However, if Al exceeds 0.060% and N exceeds 0.0120%, the effects are impaired. .
01% and N: 0.0030%, upper limit is Al: 0.06% and N: 0.01
20%.

In the case of MnS or MnSe, at least one selected from Se and S: 0.005 to 0.3.
The ranges of 060% Se and S are also set in the above ranges for the same reason as in the case of the AlN system described above. MnS described above
, MnSe-based and AlN-based are preferably used together in terms of electromagnetic characteristics.

The inhibitor components include S, S described above.
e, Al, Cu, Ni, Sn, Cr, Ge, Sb, Mo, Zn, Te, Bi
And P etc. are also advantageously used, so that they can be contained together in small amounts. Here, the preferable addition ranges of the above components are Cu, Ni, Sn, Cr: 0.01 to 0.15%, Ge, S
b, Mo, Zn, Te, Bi: 0.005 to 0.1%, P: 0.01 to 0.2
%, And each of these inhibitor components can be used alone or in combination.

The silicon steel slab having the above-described composition is manufactured by continuous casting or the like from molten steel produced by melting a predetermined component. And this silicon steel slab is hot
It is heated to 1300 ℃ or more and hot rough rolling is performed. Hot finish rolling entry side temperature of 1100 ° C. or higher 1250 ° C. or less, finish rolling delivery temperature to implement the finish rolling to secure the 1050 ° C. greater. Immediately after finish rolling, it is quenched, and the temperature is reduced to 700 ° C or less and winding is performed.

If the entry temperature of hot finish rolling exceeds 1250 ° C., recrystallization occurs during finish rolling, which is disadvantageous in terms of electromagnetic characteristics.
If the temperature is lower than 1100 ° C., the inhibitor on the surface of the plate becomes coarse at the plate edge, so that the electromagnetic characteristics are deteriorated. To refine the deposition of AlN introduces distortion in the finish rolling is achievable by quenching thereafter, terminates the finish rolling at 1050 ° C. greater, it is effective then quenching method of.

If the coiling temperature is higher than 700 ° C., the coil self-annealing after coiling cannot ensure the uniformity of the inhibitor deposition in the coil. As described above, after the obtained hot-rolled sheet is subjected to one or more cold rolling operations by a known method, the surface oxide film of the steel sheet is subjected to decarburizing annealing before finish annealing, and firelite and Si
Finish annealing is performed after the composition of O _{2 has} a weight ratio of 0.2 or less. Note that the oxide film firelite and SiO ₂
Can be easily controlled by controlling the ratio between the partial pressure of water vapor and the partial pressure of hydrogen in the decarburized atmosphere.

If this ratio exceeds 0.2, the electromagnetic properties are degraded due to oxidation and decomposition of the inhibitor on the surface layer of the steel sheet during the finish annealing. By the above method, a unidirectional silicon steel sheet having good electromagnetic characteristics can be obtained industrially stably.

[0019]

【Example】

Example 1 C: 0.06%, Si: 3.05%, sol. Al: 0.023%, Mn: 0.07%
A large number of silicon slabs containing 5%, S: 0.025%, N: 0.0085%, and substantially consisting of iron and inevitable impurities, obtained by continuous casting, are heated at 1370 ° C for 30 minutes, and then finish-rolled The temperature conditions at the time were carried out under various conditions shown in Table 1, and 1.8 mm
It was hot rolled thick. Next, the hot-rolled sheet was continuously annealed at 1050 ° C., then rapidly cooled to room temperature for 60 seconds, and then cold-rolled at a reduction rate of 88.9% to a final sheet thickness of 0.23 mm. H ₂ : 25
% And N _2: was subjected to final annealing of 1200 ° C. in 75% atmosphere.

The average value of the results obtained by examining the electromagnetic properties of the final product thus obtained over the entire length of the coil is also shown in Table 1. The coil No. II of the present invention has a remarkable effect of improving the electromagnetic characteristics.

[0021]

[Table 1]

Example 2 C: 0.06%, Si: 3.05%, sol. Al: 0.028%, Mn: 0.07
A number of silicon slabs containing 0%, S: 0.020%, N: 0.0090%, and substantially consisting of iron and inevitable impurities, obtained by continuous casting, were heated at 1400 ° C for 20 minutes, and then hot-rolled. And hot-rolled to a thickness of 1.8 mm. Then hot rolled sheet 1100
After continuous annealing at ℃, rapidly cooled to room temperature for 60 seconds, then 8
Cold rolling at a rolling reduction of 7.2% to a final thickness of 0.23mm,
Subsequently, the composition of the surface oxide during the decarburization annealing was changed to 1200 ° C. in an atmosphere of H ₂ : 25% and N ₂ : 75%.
Was subjected to final annealing. FIG. 1 shows the electromagnetic characteristics and manufacturing conditions of the obtained final product.

The superiority of the present invention in the magnetic properties is recognized. Example 3 C: 0.06%, Si: 3.05%, sol. Al: 0.030%, N: 0.00
A large number of silicon steel slabs obtained by continuous casting, containing 95%, with the balance substantially consisting of iron and unavoidable impurities,
After heating for 50 minutes, change the hot rolling conditions as shown in Table 2 to 1.8m
It was hot rolled to a thickness of m. Next, the hot-rolled sheet is continuously annealed at 1050 ° C., then rapidly cooled to room temperature for 60 seconds, and then cold-rolled at a rolling reduction of 88.9% to a final sheet thickness of 0.20 mm. H ₂ for the modified composition:
A final anneal at 1200 ° C. was performed in an atmosphere of 25% and N ₂ : 75%. Table 2 shows the results obtained by examining the average value of the magnetic properties over the entire length of the coil in the final product thus obtained.

Similarly, according to the present invention, it can be seen that good electromagnetic characteristics can be obtained.

[0025]

[Table 2]

[0026]

According to the present invention, a unidirectional silicon steel sheet having good electromagnetic characteristics over the entire length of the coil can be obtained in an industrially stable manner.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between manufacturing conditions and electromagnetic characteristics.

Continuation of front page (56) References JP-A-60-197819 (JP, A) JP-A-61-12823 (JP, A) JP-A-2-133525 (JP, A) JP-A-4-154914 (JP) (A) JP-A-4-323 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C21D 8/12 C21D 9/46 501 C22C 38/00 303 C22C 38/06 H01F 1 / 16

Claims (2)

(57) [Claims] (1) Si: 2.0-4.5% by weight, C: 0.01-% by weight
0.12%, acid-soluble Al: 0.010-0.06%, N: 0.0030-0.
After the steel containing 120% is hot-rolled, the steel sheet is subjected to one or more cold rolling steps to a final thickness, and then subjected to a decarburizing annealing followed by a final finishing annealing to produce a unidirectional magnetic steel sheet. In the hot rolling, the finish-rolling inlet temperature during hot rolling was 1100
° C. or higher 1250 ° C. or less, the finish rolling exit side temperature of 1050 ° C. greater,
Immediately thereafter, cooling was performed to reduce the coiling temperature to 700 ° C or less.
A method for producing a grain-oriented electrical steel sheet having excellent magnetic properties, wherein the weight ratio of O ₂ is 0.2 or less. 2. Si: 2.0-4.5% by weight, C: 0.01-% by weight
0.12%, acid-soluble Al: 0.010-0.06%, N: 0.0030-0.
[0120] After hot rolling a steel containing Mn: 0.02 to 0.15% and further containing 0.005 to 0.060% of one or two of S or Se, the steel sheet is subjected to one or more cold rollings to obtain a final sheet thickness. None, then, to produce a grain-oriented electrical steel sheet by a series of steps of performing the final finish annealing subsequent to decarburization annealing, the finish rolling entry temperature during hot rolling is 1100 ° C or more and 1250 ° C or less,
A finish rolling delivery temperature and 1050 ° C. greater than the coiling temperature perform cooling immediately after the 700 ° C. or less, and a fayalite and SiO ₂ weight ratio of the steel sheet surface oxide film after the decarburization annealing 0.2
A method for producing a grain-oriented electrical steel sheet having excellent magnetic properties, characterized by the following.