JP3352599B2 - Manufacturing method of non-oriented electrical steel sheet with high magnetic flux density - 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 a low magnetic force and a high magnetic flux density.

[0002]

2. Description of the Related Art Conventionally, skin pass cold rolling has been performed for the purpose of reducing iron loss. Among them, the following prior arts are disclosed as prior arts in which the crystal grain size before skin pass cold rolling is disclosed. In Japanese Patent Application Laid-Open No. H2-179823, a non-directional electromagnetic treatment is performed in which the finish continuous annealing after cold rolling is performed under conditions of not less than recrystallization to an average crystal grain size of less than 20 μm, and then a final skin pass cold rolling of 3 to 15% is performed. A method for manufacturing a steel sheet is presented.

Japanese Patent Application Laid-Open No. 1-191741 discloses a method for producing a non-oriented electrical steel sheet in which a hot-rolled sheet is annealed, then cold-rolled by a 3 to 15% skin pass, and further the hot-rolled sheet is annealed and cold-rolled. Is presented. This is a technique for improving the magnetism by cold rolling a skin-passed sheet to a hot-rolled sheet and then increasing the crystal grain size of the hot-rolled sheet to a certain value or more.

[0004]

As the demand for higher motor efficiency has increased, it has become necessary to increase the efficiency of the motor even if the design magnetic flux density of the motor is reduced. As a result, there has been a demand for a non-oriented electrical steel sheet used for such motors, a material having a low magnetizing force and a high magnetic flux density. In order to satisfy this requirement, it is necessary to sufficiently increase the crystal grain size of the final product (material after annealing subsequent to skin pass cold rolling).

However, Japanese Patent Application Laid-Open Nos.
The conventional technology as disclosed in Japanese Patent Application Laid-Open No. 1-191741 cannot meet this demand. In the method disclosed in Japanese Patent Application Laid-Open No. H2-179823, the crystal grain size after annealing subsequent to skin pass cold rolling is not sufficiently large, and the magnetic flux density at low magnetizing force is not improved. Also, in Japanese Patent Application Laid-Open No. 1-191741, although the crystal grain size of the hot-rolled sheet is coarsened, this is not a technique for increasing the grain size of the final product.

[0006]

Means for Solving the Problems Accordingly, the present inventors have:
In view of the above problems, as a result of intensive studies, it has been found that the above problems can be solved by controlling the crystal grain size before skin pass cold rolling and the rolling reduction of skin pass cold rolling. The contents are as follows. Weight%, C ≤ 0.010%, 0.1% ≤
Si ≦ 2.0%, Mn ≦ 1.5%, Al ≦ 1.0%, P ≦ 0.15%, S ≦ 0.01
%, N ≤ 0.01%, the balance is steel consisting of Fe and unavoidable impurities, after hot rolling, without hot-rolled sheet annealing, or hot-rolled sheet annealing, or subjected to self-annealing,
After performing one or two or more cold rollings sandwiching the intermediate annealing, perform the annealing, then in the method of manufacturing a non-oriented electrical steel sheet subjected to annealing after skin pass cold rolling, the crystal grain size before skin pass, 20μm Not less than 50 μm and skin pass cold rolling reduction of 3% or more and 12% or less, or 50 μm or more and 20% or less
If it is 0 μm or less, 12% ≧ skin pass cold rolling reduction [%] ≧ 0.
Non-directional electromagnetic with high magnetic flux density characterized by cold rolling of skin pass under the condition of 04 × grain size before skin pass [μm] + 1
This is a method for manufacturing a steel sheet.

In addition, Ni ≦ 2.0%, Sn ≦
A method for producing a non-oriented electrical steel sheet having a high magnetic flux density as described above, characterized by containing 0.50% and Cu ≦ 1.0% .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below.
First, the reasons for limiting the components of the present invention will be described. C is a harmful component that increases iron loss and causes magnetic aging. Therefore, the content of C is set to 0.010% or less.

As is well known, Si is an element effective in reducing iron loss, and it is necessary to contain 0.1% or more to obtain this effect. On the other hand, when the content increases, the magnetic flux density decreases, the rolling workability deteriorates, the finish annealing temperature increases, and the cost increases, so that the content is set to 2.0% or less. Mn is an element effective in reducing iron loss like Si, but when it exceeds 1.5%, the magnetic flux density decreases, so it is set to 1.5% or less. If Mn is less than 0.05%, the magnetic characteristics deteriorate, so the lower limit is made 0.05%.

Al, like Si, has the effect of increasing the specific resistance and lowering the iron loss, and therefore may be included. However, in the present invention, there is no particular lower limit since the specific resistance may be increased by using Si. On the other hand, when the Al content increases, the magnetic flux density decreases. In addition, since Al has the effect of reducing solid solution N and suppressing the fine precipitation of nitrides, B is added when the amount of Al is low, and N is coarsely precipitated in the form of BN to be harmless. This does not impair the present invention.

If P exceeds 0.15%, iron loss increases, so P is set to 0.15% or less. If S exceeds 0.01%, sulfides such as MnS precipitate finely, hindering grain growth during finish annealing and increasing iron loss. N is 0.01
%, Nitrides such as AlN precipitate finely, hindering grain growth during finish annealing and increasing iron loss.
The following is assumed.

[0012] Ni is added to improve the saturation magnetization and improve the texture, but excessive addition causes an increase in cost, so Ni is set to 2% or less. Sn is added to improve the texture, but excessive addition increases the cost and deteriorates the brittleness.
0.5% or less. Cu is added because it improves the texture, but excessive addition is made 1.0% or less because surface flaws during hot rolling increase.

The lower limit amounts of Ni, Sn, and Cu are determined from the viewpoint of the texture improvement effect that affects the magnetic properties.
Ni: 0.1%, Sn: 0.01%, Cu: 0.05% are the lower limits. Next, the reasons for limiting the manufacturing method will be described. The present inventors examined the crystal grain size [μm] before skin pass cold rolling and the skin pass cold rolling rate [%], and found that there was a certain relationship between the two as shown in FIG. Was. That is, if the skin pass rolling reduction is too high, recrystallization nuclei are newly generated in subsequent annealing, and the crystal grain size after annealing subsequent to skin pass cold rolling becomes fine, and ΔB1 does not improve. . If the skin pass rolling reduction is too low, the driving force for grain growth decreases in the subsequent annealing, and the crystal grain size after annealing subsequent to the skin pass cold rolling does not become coarse and ΔB1 does not improve.
If the grain size before skin pass cold rolling is too small, the number of nuclei that grow in the grain size after annealing after skin pass cold rolling increases, and the crystal grain size after annealing after skin pass cold rolling becomes fine. 200 μm
The following is assumed. Between these effects, as shown in Examples, when the crystal grain size before skin pass cold rolling is 50 to 200 μm, 12% ≧ skin pass cold rolling rate [%] ≧ 0.04 × crystal grain size before skin pass [μm This range is used because it is better in the range of [+1]. Here, B1 indicates the magnetic flux density [T] when H is 100 [A / m]. ΔB1 means the difference between B1 when the material after cold rolling and annealing is annealed without skin pass cold rolling and B1 when the material is annealed with skin pass cold rolling.

[0014]

【Example】

(Example 1) An example is shown below. The starting material was steel having the components shown in Table 1, and the process was hot-rolled, cold-rolled, annealed, skin-pass cold-rolled, held at 750 ° C for 2 hours, and then cooled in the furnace.

[0015]

[Table 1]

Table 2 shows the crystal grain size before skin pass cold rolling and ΔB1 when the skin pass cold rolling reduction was variously changed.
When the particle size before skin pass cold rolling is 20 μm or more and less than 50 μm, ΔB1 is improved by setting the skin pass cold rolling reduction to 3% or more and 12% or less. Also, 50μm
12% ≧ Skin pass ratio [%] ≧ 200 μm
ΔB1 is improved by setting 0.04 × the crystal grain size before skin pass [μm] +1.

[0017]

[Table 2]

Example 2 A non-oriented electrical steel sheet was manufactured in the same process as in Example 1, except that the starting material was steel having the components shown in Table 3. As shown in Table 4, it can be seen that the same effects as in Example 1 were obtained even when Ni, Sn, and Cu were added.

[0019]

[Table 3]

[0020]

[Table 4]

[0021]

As described above, according to the present invention, a non-oriented electrical steel sheet having a low magnetic force and a high magnetic flux density can be obtained.
It can sufficiently meet the demand for non-oriented electrical steel sheets used as core materials for high-efficiency motors, and its industrial effect is very large.

[Brief description of the drawings]

FIG. 1 shows the relationship between the crystal grain size before skin pass cold rolling and the rolling reduction of skin pass cold rolling.

Continuation of the front page (56) References JP-A-62-130259 (JP, A) JP-A-2-179823 (JP, A) JP-A-5-140648 (JP, A) JP-A-2-263952 (JP) (A) JP-A-6-287640 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C21D 8/12 C22C 38/00 303 C22C 38/06 H01F 1/16

Claims (2)

(57) [Claims] (1) In terms of% by weight, C ≦ 0.010%, 0.1% ≦ Si ≦ 2.0%, Mn ≦ 1.5%, Al ≦ 1.0%, P ≦ 0.15%, S ≦ 0.01%, N ≦ 0.01%. , The rest being steel consisting of Fe and unavoidable impurities,
After hot rolling, as it is, without hot-rolled sheet annealing, or hot-rolled sheet annealing, or self-annealing, perform cold rolling once or twice or more with intermediate annealing, then perform annealing, and then continue In the method for producing a non-oriented electrical steel sheet subjected to annealing after skin pass cold rolling, if the crystal grain size before skin pass is 20 μm or more and less than 50 μm, the skin pass cold rolling rate is 3%.
If it is not less than 12% or not less than 50 μm or not more than 200 μm, cold rolling of skin pass is performed under the condition of 12% ≧ skin pass cold rolling rate [%] ≧ 0.04 × crystal grain size before skin pass [μm] +1. High magnetic flux density
Manufacturing method of non-oriented electrical steel sheet. 2. The magnetic flux density according to claim 1, wherein the steel further contains Ni ≦ 2.0%, Sn ≦ 0.50%, Cu ≦ 1.0% by weight.
Highly non-oriented electrical steel sheet manufacturing method.