JP3350351B2 - Manufacturing method of non-oriented electrical steel sheet with excellent shape and 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 non-oriented electrical steel sheet having excellent shape and magnetic properties, which is used for motors and small transformers in the electric industry.

[0002]

2. Description of the Related Art In general, non-oriented electrical steel sheets are used for motor cores and small transformers, and are punched into predetermined dimensions and laminated. In recent years, this punching, laminating, caulking or welding process has been almost automated,
In order to realize smooth production in each of these processes, there is an increasing demand for non-oriented electrical steel sheets having a flat shape.

[0003] Since the non-oriented electrical steel sheet after cold rolling has an edge wave at the end and a medium elongation near the center in the width direction, conventionally, tension is applied in the length direction in the next continuous annealing step. Shape correction. As a method of correcting the shape in the annealing step, for example, Japanese Patent Publication No. 58-1173 discloses that the elongation rate of a steel sheet is controlled to about 0.1 to 5.0% in accordance with the annealing temperature. There is disclosed a method for obtaining a non-oriented electrical steel sheet having excellent iron loss by setting an elongation rate such that the elongation becomes as large as possible. However, in this method, it is necessary to increase the elongation rate to as large as 2 to 3% as shown in FIG. 1 in the high-temperature side, for example, at 1000 ° C. × 2 domains. Therefore, there is a problem that the steel sheet is easily broken.

Japanese Patent Application Laid-Open No. Hei 3-223422 discloses that the high temperature range of continuous annealing is set to low tension, the low temperature cooling range is set to high tension, and the cooling speed in the width direction in the cooling zone is controlled. A method is disclosed for improving both magnetism and shape. However, in order to separate the tension in the first half and the second half in the annealing furnace in the actual furnace operation, large facilities such as bridal rolls or rolling rolls that take large contact with the steel sheet are required, so investment costs and rolls There was a problem in terms of durability at high temperatures.

[0005]

SUMMARY OF THE INVENTION The present invention is to provide a method for producing a non-oriented electrical steel sheet which does not have the problems as in the above-mentioned conventional method and has both excellent magnetic properties and shape.

[0006]

SUMMARY OF THE INVENTION The present invention provides a method for preparing C
≦ 0.01%, Si ≦ 4%, Al ≦ 2%, Mn ≦ 1.5
%, P ≦ 0.3%, S ≦ 0.02%, N ≦ 0.005%
Containing the balance Fe and incidental molten steel consisting of impurities was continuously cast slabs and without, after hot rolled, in the manufacturing method of the non-oriented electrical steel sheet to continuous annealing cold-rolled, continuously <br/> annealing When performing a shape correction by disposing a hot leveler in one or both of the heating zone and the cooling zone of the furnace, the elongation rate of the steel sheet by the hot leveler is set to 0.01 to 2 in the heating zone leveler in the heating process. % In a cooling zone leveler in a cooling process , and 0.01 to 0.5%. This is a method for producing a non-oriented electrical steel sheet having excellent shape and magnetic properties.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing a non-oriented electrical steel sheet according to the present invention, the following points have been considered. First, continuous annealing
Install a hot leveler in the heating zone or cooling zone in the furnace , and correct the shape with the hot leveler. Second, the elongation of the steel sheet during the heating process, in which the recrystallized grain size of the steel sheet is still small, has a small adverse effect on the magnetic properties. Deterioration. Third, depending on the location of the hot leveler,
It is possible to produce a non-oriented electrical steel sheet having both excellent magnetic properties and shape. Generally speaking, conventional shape correction is performed by applying tension in the high-temperature soaking part of the annealing furnace to extend the steel sheet. Was. In the present invention, adopting shape correction by a hot leveler using a short-time bending at low temperature, at the same time, performing elongation control focusing on dynamic changes during annealing of the steel sheet crystal structure, without breaking The object of the present invention is to obtain a non-oriented electrical steel sheet capable of correcting the shape of a steel sheet and having excellent shape and magnetic properties.

Hereinafter, the present invention will be described in detail. In the present invention, the component composition of the molten steel is specified by weight% as follows.

[0009] The C content is 0.01% or less. 0.01 %
When the time exceeds, the time required for decarburization in the decarburization annealing becomes long, and the productivity decreases. The C content in the product is preferably 0.005% or less in order to eliminate the problem of magnetic aging. The amount of Si is set to 4% or less. Si is necessary to reduce iron loss, but if it is too much, there is a problem of embrittlement, which causes a break in a threading line and a trouble when punching into a motor core. This limit is 4%. Therefore, the upper limit is set to 4% or less.

The Al content is 2% or less. Al is effective in reducing iron loss, but is limited to 2% or less due to the problem of addition cost. The Mn content is 1.5% or less. Mn
Is necessary to suppress precipitate FeS to MnS as a countermeasure for the occurrence of lubrication in hot rolling, but is set to 1.5% or less because of the problem of addition cost. The P content is limited to 0.3% or less. P is useful to reduce burrs and sagging when punching the motor core at the customer, but 0.3%
If it exceeds the maximum value, the segregation in the steel sheet central layer causes troubles such as cracking. Therefore, the upper limit is set to 0.3%.

[0011] The N content is 0.005% or less. If the N content is large, blisters called blisters on the surface of the steel sheet occur, so the content is limited to 0.005% or less. S content is 0.02
% Or less. Since S forms sulfides and deteriorates iron loss, a smaller amount is better limited to 0.02% or less.

As other components, known Cu, Cr, Sn, Ni, and B may be used to further improve the texture of the product. As the content, Cu: 0.02 to
0.2%, Sn: 0.01 to 0.35%, Cr: 0.0
4 to 0.2%, Ni: 0.01 to 0.3%, B: 0.0
005 to 0.01% is preferred, and two or more of these components may be added in combination.

Molten steel having these component compositions is formed into a slab by ordinary continuous casting, and hot-rolled by a conventional method to form an ordinary hot-rolled coil having a thickness of 1.0 to 3.0 mm. This hot rolled coil may or may not be annealed. Annealing increases the magnetic flux density, but increases the cost of annealing. Therefore, this annealing is selectively performed as necessary in consideration of the balance between cost and effect.

Next, the sample is cold-rolled to the usual 0.15-1.
Continuous annealing is performed after the steel sheet has a thickness of 2 mm. The ultimate temperature of the continuous annealing is 650 to 1200 ° C.
However, the higher the temperature, the larger the crystal grain size and the higher the iron loss. The annealing atmosphere is a commonly used mixed atmosphere of hydrogen, nitrogen and partial steam.

The shape correction is basically performed by a hot leveler disposed in a heating zone or a cooling zone of a continuous annealing furnace. When the cold rolled shape is poor, it is effective to correct the shape by a hot leveler during the heating and heating process. Further, in the case where the shape becomes poor due to the influence of the blow-up pressure difference in the width direction due to uneven heating or floating in the high temperature range of annealing, it is effective to perform shape correction by a hot leveler in a cooling zone.

The hot leveler may be provided in both the heating zone and the cooling zone, and the hot leveler in the heating zone and the hot leveler in the cooling zone may be selectively used as needed. A leveler may be used together. When arranging a hot leveler, it is preferable to avoid the vicinity of the highest temperature from the viewpoint of the durability of the roll, and the hot leveler in the heating zone is in a temperature-raising process region, and the hot leveler in the cooling zone is It is preferable to arrange in the cooling process area.

The shape and magnetic properties can be controlled by the elongation of the steel sheet by the hot leveler. The elongation percentage of the steel sheet by the hot leveler during the heating process is 0.0
Limit to 1-2%. If the elongation is less than 0.01%, the shape correcting action is too small, and if it exceeds 2%, the iron loss deteriorates greatly. The elongation of the steel sheet by the hot leveler in the cooling zone is limited to 0.01 to 0.5%. 0.0
If the elongation is less than 1%, the shape correcting effect is too small, and
If it exceeds 0.5%, iron loss deterioration is too large.

It is preferable to use a hot leveler composed of two or more conventional leveler rolls. The elongation of the steel sheet can be controlled by controlling the amount of indentation of the leveler roll (inter mesh), the temperature of the steel sheet (the strength of the steel sheet at that temperature), and the tension on the steel sheet. In this case, since the hot strength of the steel sheet varies depending on the composition and structure of the steel sheet, attention must also be paid to this aspect.

[0019]

Embodiments of the present invention will be described below. 0.002% C, 2.5% Si, 0.5% Mn,
0.03% P, 0.2% Al, 0.001% S, 0.0
Continuous casting slab of molten steel containing 02% N at 1150 ° C
And hot-rolled to obtain a hot-rolled sheet having a thickness of 2.5 mm.
A 5 mm steel plate was used. The shape of this steel sheet after cold rolling was normal ear waves and medium elongation.

Next, after degreasing the steel sheet,
Continuous annealing was performed in a 30% H ₂ + 70% N atmosphere in a continuous annealing furnace at an ultimate temperature of 1000 ° C. and a soaking time of 10 seconds.
The tension of the steel sheet in the continuous annealing furnace was 0.4 kg / mm ² , and the heating rate in the heating zone was about 50 ° C./sec.

A hot leveler (three rolls) is disposed in a zone where the temperature of the steel sheet at the time of temperature rise is 740 ° C. and a zone where the temperature of the steel sheet during the cooling is 700 ° C., and one of the hot levelers is selected. Alternatively, the shape of the steel sheet was corrected in an annealing furnace using both hot levelers in combination, and the shape and magnetic properties (iron loss) of the steel sheet were measured. Table 1 shows the evaluation results together with the results of the comparative examples.

The shape of the steel sheet is indicated by a value obtained by measuring the maximum height on a surface plate after shearing the steel sheet to a width of 100 mm, and subtracting the thickness from the measured value. Is superior. The magnetic properties (iron loss) were obtained by measuring in the L + C direction of Epstein materials, and here, the iron loss was 3.26 to 3.75 w / k.
g, the magnetic flux density B ₅₀ is 1.67T is within a satisfactory range.

[0023]

[Table 1]

As shown in Table 1, in the test No. 1 in which the elongation percentage of the steel sheet in the hot leveler falls within the range of the present invention. 3 to 7, Experiment NO.
12 to 16, Experiment NO. In the case of 19 to 21, the shape of the steel plate is 0.1.
07 mm or less, the iron loss was 3.26 to 3.75 w / kg, the magnetic flux density was 1.67 T, and a non-oriented electrical steel sheet excellent in both shape and magnetic properties was obtained. However, in the experiment NO. 1 in which the elongation rate of the steel sheet in the hot leveler was out of the range of the present invention. 1-2,
Experiment NO. 8 to 11, Experiment NO. In Nos. 17 to 18, either the shape or the magnetic properties (iron loss) were unsatisfactory, and a non-oriented electrical steel sheet excellent in both the steel sheet shape and the magnetic properties (iron loss) was not obtained.

[0025]

As described above, in the present invention, a non-oriented electrical steel sheet having excellent magnetic properties as well as its shape can be obtained by installing a hot leveler in a continuous annealing furnace and controlling the elongation of the steel sheet. be able to.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C21D 8/12 C22C 38/00 303 H01F 1/16

Claims (1)

(57) [Claims] C. ≦ 0.01%, Si ≦ 4%, Al ≦ 2%, Mn ≦ 1.5%, P ≦ 0.3%, S ≦ 0.02%, N ≦ 0 in weight%. containing .005%, the balance Fe and incidental molten steel consisting of impurities was continuously cast slabs and without, after hot rolled, in the manufacturing method of the non-oriented electrical steel sheet to continuous annealing cold-rolled, continuously <br When a hot leveler is arranged in one or both of the heating zone and the cooling zone of the annealing furnace to perform shape correction, the elongation percentage of the steel sheet by the hot leveler is set to 0. A method for producing a non-oriented electrical steel sheet having excellent shape and magnetic properties, characterized in that the content is 0.01 to 2 % and the cooling zone leveler in the cooling process is 0.01 to 0.5%.