JPH07179947A - Production of silicon steel sheet for small-size transformer - Google Patents

Abstract

PURPOSE:To obtain a silicon steel sheet useful for small-size transformer by performing the finish annealing of a rolled silicon steel sheet by means of continuous annealing in which tension in a longitudinal direction of rolling and temp. are respectively specified to reduce the iron loss value of a steel sheet in a longitudinal direction. CONSTITUTION:A hot rolled plate for nonoriented silicon steel sheet, having a composition consisting of, by weight, <=0.01% C, 2.5-5.0% Si, 0.1-1.5% Mn, <=2.0% Al, and the balance Fe with inevitable impurities, is cold-rolled once or cold-rolled while process-annealed between the cold rolled stages and worked to the final sheet thickness. Subsequent finish annealing is done by means of continuous annealing under the conditions of >=0.3kgf/mm<2> tension in the longitudinal direction of rolling of the steel sheet and of 980-1100 deg.C temp. By this procedure, the iron loss ratio between the iron loss W15/50(L) in the longitudinal direction of rolling of the steel sheet and the iron loss W15/50(C) in a crossing direction is regulated so that C/L>=1.25 is satisfied. By this method, the iron loss value in the L direction can be reduced by increasing tension at the time of annealing, and the silicon steel sheet capable of being advantageously utilized for a small-size transformer as specific purpose can be obtained.

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 high-grade electromagnetic steel sheets, and more particularly to a method for manufacturing electromagnetic steel sheets for small transformers.

[0002]

2. Description of the Related Art Small transformers are widely used as power transformers and transformers for household electric appliances, ballasts for fluorescent lamps, and the like. In recent years, household electric appliances have been required to be lighter and smaller, and transformers have also been required to be smaller and lighter. On the other hand, these transformers have to be inexpensive and can be miniaturized by using unidirectional electrical steel sheet or the like, but this is disadvantageous in terms of cost. Has been used. The non-oriented raw material steel plate is used after the raw material steel plate manufactured by the steel manufacturer is punched by the transformer manufacturer.

The shape to be punched at this time is designed so that the longitudinal direction (L) of the steel sheet is larger than that in the transverse direction (C). The reason is iron loss W in the longitudinal direction.
The iron loss ratio C / L of _15/50 (L) and the iron loss W _15/50 (C) in the transverse direction is about 1.1 to 1.2, that is, the iron loss in the longitudinal direction (L) is the transverse direction (C ) Is 10 to 20% better than the iron loss.

The iron loss of W _{15/50 is} an iron loss (W / kg) measured at 50 cycles for 1.5 Tesla. On the other hand, the non-oriented electrical steel sheet reduces the magnetic anisotropy as disclosed in JP-A-62-102507, JP-A-1-92318 and JP-A-3-271323. Various measures have been taken to improve the magnetism.

Therefore, the shape of the small transformer has also been made uniform (eg, EI core). More special shapes (eg
The same applies to the LT core). In order to improve these performances and downsize them, higher-grade electromagnetic steel sheets will be used, but in order to further improve them, it is necessary to upgrade the shape of high-grade electromagnetic steel sheets along with changing the shape of small transformers. .

[0006]

As one of the measures to be taken by the present invention, the present invention aims to improve the magnetism in the longitudinal direction (L) of the steel sheet, that is, the iron loss ratio in the longitudinal direction (L) and the transverse direction (C) of the steel sheet. The object of the present invention is to provide a method for manufacturing a magnetic steel sheet for a small transformer with C / L ≧ 1.25.

[0007]

The present invention is based on C, in weight percent.
Is 0.01% or less, Si is 2.5 to 5.0%, Mn is 0.1 to 1.5%,
After hot rolling a non-oriented electrical steel sheet with Al of 2.0% or less and the balance of unavoidable impurities and iron, cold rolling is performed once or twice to form the final thickness after intermediate annealing, and then finished. Annealing is performed by rolling the steel sheet in the longitudinal direction with a tension of 0.3 kgf / mm ² or more and a temperature of 9
Performed by continuous annealing at 80 ° C to 1100 ° C, the iron loss W _15/50 (L) in the rolling longitudinal direction and the iron loss W in the transverse direction of the steel sheet.
An iron loss ratio of _15/50 (C) is C / L ≧ 1.25.

[0008]

It has been conventionally known that when the tension in the longitudinal direction (L) of a steel sheet during finish annealing is increased, the iron loss in the longitudinal direction (L) is improved and the iron loss in the transverse direction (C) is deteriorated. ing. The prior art described above also pays attention to this fact, but aims to reduce the difference in iron loss between the longitudinal direction (L) and the transverse direction (C) of the steel sheet because the purpose is to improve overall magnetism. I am trying.

According to the present invention, the iron loss ratio in the longitudinal direction (L) and the transverse direction (C) of the steel sheet is increased on the basis of the idea opposite to the prior art. The loss ratio is C / L ≧ 1.25. The component composition of the material targeted by the present invention will be described. C is a harmful element from the viewpoint of magnetic properties, and it is preferable to reduce it as much as possible. Therefore, it is limited to 0.01% or less.

Since Si is a useful element for reducing iron loss by increasing the specific resistance, the lower limit was made 2.5% in order to reduce iron loss. If the upper limit exceeds 5.0%, cold ductility is impaired, so the upper limit was made 5.0%. Mn addition is effective in reducing the amount of solid solution S during heating of the slab, and is added to suppress hot embrittlement due to S, but if it is less than 0.1%, the addition effect is poor. %, The magnetic properties are deteriorated, so the content is limited to 0.1 to 1.5%.

Al is effective for deoxidizing steel and reducing the amount of AlN-based precipitates, and, like Si, increases the specific resistance,
Although it is a useful component for improving iron loss, if it exceeds 2.0%, the cold rolling property deteriorates, so the content was limited to 2.0% or less. A hot-rolled sheet of a non-oriented electrical steel sheet containing the above components, the balance being unavoidable impurities and iron, is made into a product thickness by one cold rolling, or cold rolled twice by sandwiching an intermediate rolling. The product thickness may be obtained by rolling, or the hot rolled sheet may be annealed and then cold rolled once to obtain the product thickness.

When the final annealing is performed under the tension in the longitudinal direction of the steel sheet after the final thickness is processed, the tension is 0.3 kgf /
An annealing temperature of 980 ° C to 1100 ° C is required for mm ² or more. Figure 1
Figure 3 shows the relationship between the annealing conditions and electromagnetic characteristics when hot-rolled Si 3.2% was annealed, cold-rolled to 0.50 mm, and subjected to finish annealing. Regarding the electromagnetic characteristics, the values in the longitudinal direction of the steel sheet are shown. Further, the iron loss ratio C / L = 1.25 of the value (L) in the longitudinal direction and the value (C) in the transverse direction of the steel sheet was shown.

Iron loss value W in the longitudinal direction of a non-oriented electrical steel sheet
_An annealing temperature of 980 ° C or higher is required to obtain the highest grade of _15/50 ≤ 2.10 w / kg. On the other hand, when the annealing temperature exceeds 1100 ° C, the magnetic properties are good, but the load on the annealing furnace is large, which is not economical. Further, when the tension is changed, there is a risk that the plate width will be reduced. Therefore, the annealing temperature is 980
Limited to ℃ ~ 1100 ℃.

Further, in order to set the iron loss ratio C / L in the longitudinal direction (L) and the transverse direction (C) of the steel sheet, which is a feature of the present invention, to 1.25 or more, the tension during annealing is 0.3 kgf / mm ² or more. Need to By performing finish annealing under the above conditions,
The iron loss ratio in the longitudinal direction (L) and transverse direction (C) of the steel sheet is C /
L ≧ 1.25, iron loss value in the longitudinal direction W _15/50 ≦ 2.10 w /
Excellent magnetic steel sheet for small transformer can be obtained.

[0015]

Example: C: 0.004% by weight, Si: 3.18%, Mn: 0.
32%, Al: 0.41%, the balance unavoidable impurities and iron hot-rolled sheet was annealed at a temperature of 1000 ℃ for 1 minute in a continuous annealing furnace, then cold rolled to a final sheet thickness of 0.50 mm It was The final finish annealing was performed in a continuous annealing furnace under various tensions at a temperature of 1000 ° C for a time of 30 seconds. Table 1 shows the iron loss value W _15/50 of the obtained steel sheet.

[0016]

[Table 1]

In the case of the present invention, the iron loss ratio in the longitudinal direction (L) and the transverse direction (C) of the steel sheet is C / L ≧ 1.25. The conventional material had C / L = 1.14 to 1.16.

[0018]

INDUSTRIAL APPLICABILITY The present invention manufactures a non-oriented electrical steel sheet having a superior iron loss value in the longitudinal direction, and in particular, C / L ≧ 1.25 in terms of the iron loss ratio in the longitudinal direction (L) and the transverse direction (C). In the manufacture of
By increasing the tension at the time of annealing, which has been avoided in the past, the iron loss value in the L direction can be reduced and it can be advantageously used for electromagnetic steel sheets for small transformers for specific applications.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between longitudinal tension and iron loss value.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location C22C 38/06 (72) Inventor Toshinori Nakanishi 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama (No address) Kawasaki Steel Mizushima Steel Works, Ltd. (72) Inventor Toko Teshiba 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Prefecture (without street number) Kawasaki Steel Works, Mizushima Steel Works

Claims (1)

[Claims] 1. By weight%, C is 0.01% or less, and Si is 2.5-.
5.0%, Mn 0.1-1.5%, Al 2.0% or less, and the balance of the hot-rolled sheet for non-oriented electrical steel sheet consisting of inevitable impurities and iron is cold-rolled once or twice with intermediate annealing. After finishing to the final plate thickness, finish annealing is performed by continuous annealing at a tension of 0.3 kgf / mm ² or more in the rolling longitudinal direction of the steel sheet and at a temperature of 980 ° C to 1100 ° C. _15/50 (L)
And the iron loss ratio of the transverse iron loss W _15/50 (C) is C / L ≧ 1.
25. A method of manufacturing a magnetic steel sheet for a small transformer, characterized in that the number is 25.