JPH08109449A - Nonoriented silicon steel sheet high in magnetic flux density and low in core loss, its production and motor core using the same - Google Patents

Abstract

PURPOSE: To produce a nonoriented silicon steel sheet high in magnetic flux density and low in core loss by incorporating a small amt. of Ni into a steel having a specified compsn. and regulating the grain size of the hot rolled sheet to certain value or above by annealing. CONSTITUTION: A steel contg., by weight, 0.010% C, 0.1 to <1.9% Si, 0.1 to <1.0% Mn, 1 to <1.9% Al, Si+Al<2, 0.1 to 3% Ni, and the balance Fe is subjected to hot rolling and is thereafter subjected to hot rolled sheet annealing or self annealing to regulate the average grain size of the hot rolled sheet to >=100μm. Next, it is subjected to cold rolling for one time or two or more times including process annealing and is subjected to continuous annealing. Thus, the nonoriented silicon steel sheet in which the value of B50 in the C direction is higher than the value of B50cal(C) prescribed by the formula of B50cal(C)=6.500×10<-3> ×Ni-1.350×10<-2> ×-(Mn+0.116)<2> -5.590×10<-3> ×(Si+2.406)<2> --0.055×Al+1.797 and having high magnetic flux density and low core loss can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss, which is used as a core material for electric equipment, a method for producing the same, and a high magnetic flux density material used for the electric equipment. The present invention relates to a motor core using a grain-oriented electrical steel sheet.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for higher efficiency of electric equipment in a global movement for saving electric power and energy. Further, with the miniaturization of electric devices, there is an increasing demand for higher magnetic flux density of magnetic materials. Therefore, even in non-oriented electrical steel sheets which are widely used for iron core materials such as rotating machines and small and medium-sized transformers, there is an increasing demand for higher magnetic flux density and lower iron loss.

In the conventional non-oriented electrical steel sheet, a method of increasing the content of Si, Al or the like has been generally used as a means for reducing the iron loss from the viewpoint of reducing the eddy current loss due to an increase in the specific resistance. However, this method has an essential problem that it cannot avoid a decrease in magnetic flux density.

In addition to simply increasing the content of Si or Al, it is also possible to reduce C, S, or
Manufacture of component treatment such as addition of B, increasing cold rolling reduction before finish annealing, and increasing finish annealing temperature, as described in JP-A-58-15143. Although the process has been devised, in either case, the iron loss can be reduced, but it is not so effective in improving the magnetic flux density, and the non-directional electromagnetic having a high magnetic flux density and a low iron loss. We were unable to meet the request to manufacture steel sheets.

[0005]

In view of the above problems, it is an object of the present invention to provide a non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss, a method for manufacturing the same, and a motor core using the steel sheet. It is what

[0006]

The inventors of the present invention have obtained a non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss by devising manufacturing process conditions and positively utilizing a trace amount of additive elements in combination. We have been making intensive studies from the perspective of whether or not there is any. As a result, it is possible to increase the magnetic flux density and reduce the iron loss by containing a small amount of Ni in steel and increasing the crystal grain size of the hot-rolled sheet to a certain value or more by hot-rolled sheet annealing or self-annealing. Investigated.

As inventions showing that Ni is contained, JP-A-3-281758 and JP-A-5-186833 are available.
Japanese Patent Laid-Open No. 5-186834.
In JP-A-3-281758, Al + Si: 2 to
It is disclosed to contain 5%. Since Si and Al have a function of lowering the saturation magnetic flux density, if they are contained in this amount, it is essentially impossible to produce a magnetic steel sheet having a high magnetic flux density. Further, the manufacturing method is also premised on decarburization, so that the manufacturing cost becomes very high.

[0008] As an example in which Ni is contained in a non-oriented electrical steel sheet, JP-A-63-317627 and JP-A-1-13 are cited.
There is a 9721 publication. These all have a Mn content of 1%
As described above, the purpose is to improve the characteristics by the synergistic effect of Mn and Ni, and the magnetic flux density is not sufficient in the steel sheet manufactured by this technique. In addition, Ni is used for the non-oriented electrical steel sheet for the purpose of obtaining the characteristics of corrosion resistance and high tensile strength.
JP-A-5-255817 and Japanese Patent Application Laid-Open No. 64-64817
No. 226 is available, all of them add Cr, Mo and the like in combination for the purpose of improving the corrosion resistance and the strength of the steel sheet, and the component range and purpose are different from the present invention.
As described above, the magnetic flux density is not sufficient in the conventional technique.

In Japanese Patent Laid-Open No. 5-186833 and Japanese Patent Laid-Open No. 5-186834, finish annealing is performed in the γ region, and the annealing cycle is elaborated so that {11
Although an invention relating to a manufacturing method aiming at reducing the ratio of 1} / {100} orientations has been proposed, Ni is not positively utilized for improving the texture texture, but only Mn, Cr is used. , Mo, just used to increase the strength.

Further, examples of the technique in which the magnetic steel sheet is used for the core are found below. In Japanese Unexamined Patent Publication No. 4-361508, a core is filled with an impregnating material having a surface roughness Rmax of 3.5 μm or more, and a low magnetostrictive material of Si: 4.9 to 7.1 wt% is used to cause magnetostriction. It is characterized by suppressing core vibration. In addition, JP-A-4-3681
No. 03 publication, Si: 4.5 to 7 wt% in a part of the core.
It is characterized by suppressing the vibration of the entire core due to the magnetostriction by using the low magnetostrictive material. Since the above two techniques contain Si as high as around 6.5%, the saturation magnetization becomes low, and the magnetic flux density cannot be essentially increased.

Further, in Japanese Patent Laid-Open No. 6-45131,
It is characterized by using a material having better magnetic properties in the width direction than in the length direction, but it is costly to manufacture a material satisfying this. As described above, it is not possible to inexpensively obtain a high magnetic flux density magnetic steel sheet with the above techniques.

On the other hand, in the present invention, by adding a small amount of Ni to steel having an essentially high magnetic flux density of Si + Al of less than 2% and positively utilizing Ni for texture improvement, it is possible to reduce the cost. A non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss can be obtained. That is, the combination of the manufacturing process devised to increase the crystal grain size of the hot-rolled sheet to 100 μm or more by hot-rolled sheet annealing or self-annealing and the positive utilization of Ni, which is a trace additive element, increases the magnetic flux density. It was also found to be effective in reducing iron loss.

The present invention has been made on the basis of these findings. The first gist of the present invention is C: 0.0 by weight%.
10% or less, Si: 0.1% or more and less than 1.9%,
Mn: 0.1% or more and less than 1%, Al: 0.1% or more and less than 1.9%, Si + Al: less than 2%, Ni:
0.1% or more and 3% or less, and the balance is Fe and unavoidable impurity elements, and the B50 value in the C direction is as follows (1).
A non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss, which is characterized by being larger than the value of B50cal (C) defined by the formula. B50cal (C) = 6.500 × 10 ⁻³ × Ni−1.350 × 10 ⁻² × (Mn + 0.116) ² −5.590 × 10 ⁻³ × (Si + 2.406) ² −0.055 × Al + 1 .797 ・ ・ ・ ・ ・ ・ ・ ・ (1)

A second aspect of the present invention is, in wt%, C:
0.010% or less, Si: 0.1% or more and 1.9%
Less than, Mn: 0.1% or more and less than 1%, Al: 0.1%
Or more and less than 1.9%, Si + Al: less than 2%, N
i: 0.1% or more and 3% or less, the balance being Fe and inevitable impurity elements, and the B50 value of L + C being larger than the value of B50cal (L + C) defined by the following formula (2). It is a non-oriented electrical steel sheet with high density and low iron loss. B50cal (L + C) = 2.221 × 10 ⁻² × Ni−1.350 × 10 ⁻² × (Mn + 0.116) ² −5.590 × 10 ⁻³ × (Si + 2.406) ² −0.055 × Al + 1 805 ・ ・ ・ ・ ・ ・ ・ ・ (2)

A third aspect of the present invention is that the content of Ni is more than 1% and not more than 3%, and the magnetic flux density of the first or second aspect is high and the iron loss is low. It is in non-oriented electrical steel sheet.

The fourth gist of the present invention is to subject the steel containing the above components to hot rolling, followed by hot-rolled sheet annealing or self-annealing to make the average grain size of the hot-rolled sheet 100 μm or more, It is a method for producing a non-directional electromagnetic having a high magnetic flux density and a low iron loss, which is characterized by performing continuous annealing by performing cold rolling once or twice or more with intermediate annealing interposed.

A fifth gist of the present invention is, in a stator and / or rotor core of a rotating machine using an electromagnetic steel plate, in weight%, C: 0.01% or less, Si:
0.1% or more and 2.0% or less, Al: 2.0% or less,
Mn: 1% or less, Ni: 0.1% or more and 3% or less,
By using an electrical steel sheet composed of the balance Fe and unavoidable impurity elements, the core characteristics are significantly improved, and a high magnetic flux density and low cost core is obtained.

The details of the present invention will be described below. First, the reasons for limitation of the present invention will be described. C is a harmful component that increases iron loss and causes magnetic aging, so 0.010%
The following is assumed. As is well known, Si is an element effective in reducing iron loss, and in order to obtain this effect, it is necessary to contain Si by 0.1% or more. On the other hand, if the content increases, the magnetic flux density decreases as described above, rolling workability deteriorates, and the cost also increases, so the content is made less than 1.9%.

Mn also has the effect of increasing the specific resistance and decreasing the iron loss, but in order to obtain this effect, it is necessary to contain Mn in an amount of 0.1% or more. On the other hand, Ni, which is indispensable to the present invention, is an element that lowers the ferrite-austenite transformation temperature. Therefore, if the Mn content is too high, the ferrite-austenite transformation temperature will be too low, and Ni will cause a decrease in the strength of the non-oriented electrical steel sheet. Finish annealing in the ferrite region, which is a general condition for finish annealing, is required for a long time, which deteriorates productivity. Further, it lowers the workability in steelmaking and further increases the cost, so it is made less than 1%.

Al, like Si, has the effect of increasing the specific resistance and reducing the iron loss, so it is necessary to contain Al in an amount of 0.1% or more. When the Al content increases, the magnetic flux becomes the same as Si. Since the density decreases, it is set to less than 1.9%. As described above, Al and Si are elements that essentially reduce the magnetic flux density, so Si + Al is set to less than 2%.

When Ni is contained in an amount of 0.1% or more, the magnetic flux density can be increased and the iron loss can be reduced. On the other hand, if the content is increased, manufacturing becomes difficult in terms of cost, so the content is made 3% or less. Other than the above components, they are iron and inevitable impurity elements.

The relationship between the action of Ni, which is a feature of the present invention, and the average crystal grain size of the hot-rolled sheet will be described below. First, regarding the action of Ni, the slabs of steel having the components shown in Table 1 (shown as the components of the hot rolled sheet) were hot rolled, and then hot rolled sheet annealing was performed at 850 ° C. for 2.5 minutes. Done, then
After cold rolling to a thickness of 0.50 mm, continuous finishing annealing was performed at 850 ° C for 30 seconds, then Epstein samples were sheared, strain relief annealing was performed at 750 ° C for 2 hours, and the magnetic properties were measured. 2 shows. In Table 1, T-Al,
T in T-N is an abbreviation for Total.

[0023]

[Table 1]

[0024]

[Table 2]

From Table 2, N containing 0.1% or more of Ni was added.
o. The sample of No. 2 has no Ni added thereto. The iron loss value is lower than 1 and the magnetic flux density (B50 value) is also higher. As the added amount of Ni is increased, the iron loss value becomes lower and the magnetic flux density (B50
It was confirmed by an experiment that the value) also becomes higher and this tendency continues up to a Ni content of 3%.

No. 1, No. Textures after finish annealing of the sample of No. 3 are shown in FIGS. 2 (a) and 2 (b). From FIG. 2, (b)
No. in the figure Sample No. 3 is No. 3 in FIG. It can be seen that the {111} strength is extremely weak and the {110} strength is extremely strong as compared with the texture of 1. Thus, since Ni has the effect of improving the texture, the magnetic properties are significantly improved. By the way, from Table 2, the range of Ni is Ni: 1.
When it is more than 0% and less than 3.0%, the magnetic flux density (B5
(0 value) becomes a large value of 1.78 T or more, and the characteristics are remarkably improved. Therefore, the optimum range is Ni: more than 1.0% and not more than 3.0%.

From the above, the feature of the present invention is to produce a non-oriented electrical steel sheet having a significantly improved texture, a high magnetic flux density and a low iron loss by adding Ni. Then, the effect of the addition of Ni is enjoyed only by growing the crystal grain size of the hot-rolled sheet to a certain level or more, as shown below.

FIG. 1 shows the above-mentioned No. It shows the relationship between the hot-rolled plate crystal grain size and the magnetic properties of the product plate when the hot-rolled conditions of the samples 2 to 7 are changed to change the crystal grain size. The conditions after cold rolling are the same as those described above, that is, after cold rolling to a thickness of 0.50 mm, continuous finishing annealing is performed at 850 ° C. for 30 seconds, and then the Epstein sample is sheared and 750 2 at ℃
Temporal strain relief annealing was performed and the magnetic properties were measured. As is clear from FIG. 1, the average grain size of the hot-rolled sheet is 10
It can be seen that when it is 0 μm or more, the magnetic properties are remarkably improved, and high magnetic flux density and low iron loss can be achieved.

Next, the steel slabs having the components shown in Table 1 were hot-rolled, hot-rolled sheet annealed at 800 ° C. for 1 minute, then cold-rolled to a thickness of 0.50 mm, and then 800 ° C. 30
A continuous finish annealing was performed for 2 seconds, and then the Epstein sample was sheared and subjected to strain relief annealing at 750 ° C. for 2 hours, and the magnetic flux density (B50 value) was measured. Table 3 shows the results.

[0030]

[Table 3]

Table 3 shows the magnetic characteristics in the C direction and L + C, and the details are as follows. Regarding B50 in the C direction, the measured value of the magnetic flux density (B50 value) in the C direction when Ni is 0.00 wt% is 1.719 T, and the calculated value is 1.737 T, which is the magnetic flux density according to the equation (1). (B50
The calculated value of (value) is 0.018 T larger than the measured value. On the other hand, when Ni: 0.10 wt% or more, the actually measured value of the magnetic flux density (B50 value) in the C direction is larger than the calculated value of the magnetic flux density (B50 value) by the equation (1).

As for the L + C characteristic, Ni is 0.00 w.
The measured value of the magnetic flux density (B50 value) of L + C at t% is 1.733T, and the calculated value is 1.745T.
The calculated value of the magnetic flux density (B50 value) by the formula is 0.012 T larger than the actually measured value. On the other hand, Ni: 0.10.
At more than wt%, the magnetic flux density (B50 value) according to equation (2)
The measured value of the magnetic flux density (B50 value) in the L + C direction is larger than the calculated value of. These means that the addition of Ni significantly improved the texture and improved the magnetic flux density.

The equations (1) and (2) are set based on a lot of experimental data, and are set in the C direction and L direction, respectively.
Calculate the minimum magnetic flux density (B50 value) of + C. That is, in the present invention, it means that the magnetic flux density (B50 value) obtained by adding Ni is obtained at a value larger than the values expressed by the equations (1) and (2). (1)
In formulas (2), Ni, Mn, Si, and Al represent wt% of each element. The index of the magnetic flux density in the present invention is B5.
Let us consider it as a 0 value.

The manufacturing method of the present invention will be described below. The steel composed of the above components is melted in a converter or an electric furnace, and after continuous casting or ingot casting, slab rolling is performed to form a slab. Then, after hot rolling, hot-rolled sheet annealing or self-annealing is performed to make the average grain size of the hot-rolled sheet 100 μm.
m or more. If the average crystal grain size of the hot-rolled sheet is less than 100 μm, the effect of adding Ni is small, the magnetic flux density is high, and the iron loss is low, as already described in FIG. Next, a predetermined plate thickness is obtained by performing cold rolling twice or more with one cold rolling or intermediate annealing, and continuous finish annealing for recrystallization and grain growth is performed. By using the steel sheet of the present invention for the motor core, the exciting current of the motor can be reduced.

[0035]

Example 1 Steels having the components shown in Table 4 were hot-rolled, annealed by hot rolling under the heat treatment conditions shown in the table, and then 0.
After cold-rolling to a thickness of 50 mm, continuous finish annealing was performed at 850 ° C. for 30 seconds, then the Epstein sample was sheared, and strain relief annealing was performed at 750 ° C. for 2 hours to measure magnetic properties. The results are also shown in Table 4. As described above, it is apparent that the present invention makes it possible to manufacture a non-oriented electrical steel sheet having a significantly high magnetic flux density and a low iron loss.

[0036]

[Example 2] When a core containing Ni was used, the magnetizing force when the inner core was used as an exciting core and the outer core for the purpose of evaluating the core performance by measuring the exciting current of the core. The magnetic flux density generated in was measured, and the results are shown in FIG. At that time, the gap between the outer core and the inner core was set to 1 mm, and the generated magnetic flux density at a magnetizing force of 100 Oe was measured. As a result, in the core containing 0.1% of Ni, the magnetic flux density generated in the outer core is significantly increased as compared with the case of not containing Ni. As the Ni content increases, the generated magnetic flux density increases up to a Ni content of 3%. Therefore, by using the core of the present invention, when the exciting current is kept constant, the magnetic flux density of the core can be increased, and the motor can be downsized, the output can be increased, and the efficiency can be improved.

[0037]

[Table 4]

[0038]

As described above, according to the present invention, a non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss can be obtained.
If such a material of the present invention is used for a motor core, the exciting power of the motor can be reduced. as a result,
As electrical equipment becomes more efficient and smaller, the demand for non-oriented electrical steel sheets used as iron core materials can be sufficiently met, and its industrial effect is extremely large.

[Brief description of drawings]

FIG. 1 shows the above No. The relationship between the crystal grain size of the hot-rolled sheet and the magnetic properties of the product sheet when the crystal grain size of the samples 2 to 7 is changed by changing the hot-rolling conditions is shown.

FIG. 2 (a) is No. No. 1 sample, (b) is No. The textures of the samples of No. 3 after finish annealing are shown.

FIG. 3 shows the results of measuring the magnetizing force and the magnetic flux density generated in the outer core when the inner core is an exciting core when a core containing Ni is used.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Kubota 1-1 Tobahata-cho, Tobata-ku, Kitakyushu, Fukuoka Prefecture New Nippon Steel Corporation Yawata Works

Claims (5)

[Claims] 1. C .: 0.010% or less, Si: 0.1% or more and less than 1.9%, Mn: 0.1% or more and less than 1%, Al: 0.1% or more and 1. Less than 9%, Si + Al: less than 2%, Ni: 0.1% or more and 3% or less, and the balance Fe and unavoidable impurity elements, and the B50 value in the C direction is B50cal (C) defined by the following formula (1). A non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss, which is characterized by being larger than the value of. B50cal (C) = 6.500 × 10 ⁻³ × Ni−1.350 × 10 ⁻² × (Mn + 0.116) ² −5.590 × 10 ⁻³ × (Si + 2.406) ² −0.055 × Al + 1 .797 ・ ・ ・ ・ ・ ・ ・ ・ (1) 2. C .: 0.010% or less, Si: 0.1% or more and less than 1.9%, Mn: 0.1% or more and less than 1%, Al: 0.1% or more and 1. Less than 9%, Si + Al: less than 2%, Ni: 0.1% or more and 3% or less, balance Fe and unavoidable impurity elements, and the B50 value of L + C is B50cal (L + C) defined by the following formula (2). A non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss, which is characterized by being larger than the value. B50cal (L + C) = 2.221 × 10 ⁻² × Ni−1.350 × 10 ⁻² × (Mn + 0.116) ² −5.590 × 10 ⁻³ × (Si + 2.406) ² −0.055 × Al + 1 805 ・ ・ ・ ・ ・ ・ ・ ・ (2) 3. A non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss according to claim 1 or 2, characterized in that it contains more than 1% and less than 3% by weight of Ni. 4. A steel having the composition according to claim 1, 2 or 3 is hot-rolled and then subjected to hot-rolled sheet annealing or self-annealing to make the average grain size of the hot-rolled sheet 100 μm or more,
Then, a method for producing a non-directional electromagnetic having a high magnetic flux density and a low iron loss, which is characterized by performing continuous annealing by performing cold rolling once or twice or more with intermediate annealing interposed therebetween. 5. A motor core using a high magnetic flux density electromagnetic steel sheet, characterized in that the steel having the composition according to claim 1, 2 or 3 is used for a core of a stator and / or a rotor of a rotating machine.