JP3019705B2 - Heat treatment method of silicon steel sheet in magnetic field - 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 heat-treating a silicon steel sheet used for a low-noise transformer core material in a magnetic field in a magnetic field, and to manufacture a silicon steel sheet having low magnetostriction and low iron loss.

[0002]

2. Description of the Related Art Normally, silicon is added to an electromagnetic steel sheet widely used as a core material of a motor or a transformer. The reason why silicon is added in this way is that the addition of silicon increases electric resistance, lowers magnetic anisotropy, is inexpensive as an additional element, and forms a metallurgically stable phase. And the like. Conventionally, as a method of manufacturing a high silicon steel sheet, a rolling method (for example, Japanese Patent Publication No. 60-32705) and a siliconizing method (for example, Japanese Patent Publication No. 3-8)
No. 0846) has been established as an industrial technology. Further, it is known that a silicon steel sheet containing about 6.5 wt% of Si has a very small magnetostriction and a very good magnetic property such as a maximum magnetic permeability, and has a low-noise (low magnetostriction) transformer core. Its use as a material is drawing attention.

[0003] The effect of heat treatment in a magnetic field on a high silicon steel sheet containing 3 wt% or more of Si has been well known, and the following specific proposals have been made. Goertz casts an iron alloy containing 3 to 11 wt% Si in a ring shape in a magnetic field of 10 Oe (800 A / m).
The magnetic permeability is improved by cooling from 00 ° C. (J. Appl. Phys., 22, (7), 964, (1951)) In JP-A-57-79120, a thin steel strip obtained by ultra-rapid solidification is heat-treated at a high temperature to achieve {100}. <0
kl> or {100} <001>, and heat treatment in a specific temperature range in a magnetic field to improve the soft magnetic properties in the longitudinal direction even if the cooling rate during annealing in a magnetic field is increased to 500 ° C / min or more Suggest ways to make it happen.

In Japanese Patent Application Laid-Open No. 62-56527, 100 to
A magnetic field of 200 Oersted is applied after punching a steel plate,
It has been proposed to improve the magnetic properties by controlling the state of the precipitates in the steel sheet. JP-A-62-2
227079 and JP-A-63-26326 propose a cooling method in a magnetic field in a siliconizing method.
These documents disclose a method of applying a magnetic field in a continuous line and a method of applying a magnetic field a plurality of times, and state that a soft magnetic material can be economically obtained by these methods. JP-A-1-309922 proposes a method of applying a coating containing metal powder to a grain-oriented silicon steel sheet, and then cooling in a magnetic field to precipitate precipitates of these metal powders and improve magnetic properties. ing.

[0005]

However, although the above-mentioned heat treatment in a magnetic field can improve the magnetic characteristics, it is a method for obtaining low magnetostriction, which is a characteristic required for a low-noise transformer core. Is not valid. In the case of a high silicon steel sheet manufactured by the siliconizing method,
The Si content may vary in the inside of the steel strip, particularly in the width direction of the steel sheet, and when such a variation in the Si content occurs, it becomes difficult to control magnetic properties, iron loss, and magnetostriction, Product yield is poor.

The present invention has been made in view of such a problem of the prior art. Even with the same Si content, a smaller magnetostriction can be obtained, the noise when a transformer is formed, and the Si
An object of the present invention is to provide a heat treatment method in a magnetic field capable of stably obtaining excellent magnetostriction and iron loss characteristics even in a silicon steel sheet having a variation in the content.

[0007]

Various methods have been proposed for the heat treatment of high silicon steel sheets in a magnetic field as described above. However, in order to obtain the effect of heat treatment in a magnetic field and obtain excellent iron loss and magnetostriction. Regarding the nature of the magnetic field, which is an important requirement,
JP-A-62-56527, JP-A-62-227079
No. 10 Oe (800
Only a method of applying a magnetic field having a strength of A / m or more is disclosed.

[0008] The present inventors have conducted test research on silicon steel sheets, particularly high silicon steel sheets produced by the rolling method or the siliconizing method, in order to find out the optimal heat treatment conditions in a magnetic field, especially the properties of the applied magnetic field. As a result, it was newly found that excellent iron loss and magnetostriction can be obtained by changing the applied magnetic field when applying heat treatment in a magnetic field to AC, and furthermore, the optimum conditions for the heat treatment conditions and the strength of the magnetic field were determined. I found it. Also, this effect is irrespective of the Si content,
In addition, it was confirmed that the steel sheet could be obtained regardless of the method of producing a silicon steel sheet such as a rolling method, a siliconizing method, and a rapid solidification method. The present invention has been made based on such knowledge, and is characterized by having the following configuration.

(1) Rolling or rapid solidification
Infiltration and diffusion of silicon by silicon steel or siliconizing method
An alternating magnetic field having an effective magnetic field of 40 A / m or more is applied to the silicon steel sheet after the treatment, wherein the silicon steel sheet contains Si: 1 to 10 wt% in a temperature range lower than the Curie temperature, and is continuously heated at 400 ° C. in the magnetic field. A method for heat-treating a silicon steel sheet in a magnetic field, characterized by cooling to below.

(2) Rolling or rapid solidification
Infiltration and diffusion of silicon by silicon steel or siliconizing method
A silicon steel sheet after the treatment, wherein Si: 1 to 10 wt%,
C: 0.01 wt% or less, Mn: 0.5 wt% or less,
P: 0.01 wt% or less, S: 0.01 wt% or less, S
ol. Al: 0.2 wt% or less, N: 0.01 wt% or less, O: 0.02 wt% or less
In a temperature range below the Curie temperature, the effective magnetic field 40
A / m or more alternating magnetic field
A method for heat-treating a silicon steel sheet in a magnetic field, wherein the heat treatment is performed to a temperature of not more than 00C.

(3) Rolling or rapid solidification
Infiltration and diffusion of silicon by silicon steel or siliconizing method
An alternating magnetic field having an effective magnetic field of 40 A / m or more is applied to the silicon steel sheet after the treatment, wherein the high silicon steel sheet contains 4 to 10 wt% of Si in a temperature range lower than the Curie temperature.
A method for heat-treating a silicon steel sheet in a magnetic field, wherein the silicon steel sheet is continuously cooled to 400 ° C. or lower in the magnetic field.

(4) Rolling method or rapid solidification method
Infiltration and diffusion of silicon by silicon steel or siliconizing method
A silicon steel sheet after the treatment, wherein Si: 4 to 10 wt%,
C: 0.01 wt% or less, Mn: 0.5 wt% or less,
P: 0.01 wt% or less, S: 0.01 wt% or less, S
ol. Al: 0.2 wt% or less, N: 0.01 wt% or less, O: 0.02 wt% or less
In a temperature range below the Curie temperature, the effective magnetic field 40
A / m or more alternating magnetic field
A method for heat-treating a silicon steel sheet in a magnetic field, wherein the heat treatment is performed to a temperature of not more than 00C.

(5) Rolling method or rapid solidification method
Infiltration and diffusion of silicon by silicon steel or siliconizing method
A silicon steel sheet after the treatment, wherein Si + Sol. Al: 4 ~
An alternating magnetic field having an effective magnetic field of 40 A / m or more is applied to a silicon steel sheet containing 10 wt% in a temperature range lower than the Curie temperature, and subsequently cooled to 400 ° C. or less in the magnetic field. Medium heat treatment method.

(6) Rolling or rapid solidification
Infiltration and diffusion of silicon by silicon steel or siliconizing method
A silicon steel sheet after the treatment, wherein Si + Sol. Al: 4 ~
10 wt%, C: 0.01 wt% or less, Mn: 0.5 w
t% or less, P: 0.01 wt% or less, S: 0.01 wt%
%, N: 0.01 wt% or less, O: 0.02 wt%
An alternating magnetic field having an effective magnetic field of 40 A / m or more is applied to a silicon steel sheet containing the following in a temperature range lower than the Curie temperature, and subsequently cooled to 400 ° C. or less in the magnetic field. Heat treatment method.

[0015]

The details of the present invention will be described below, together with the reasons for its limitation. The heat treatment in a magnetic field of the present invention can be performed at the time of cooling when recrystallization annealing of a silicon steel sheet or at the time of cooling when heating the steel sheet for coating or slitting, etc. It can also be performed at the time of cooling after the Si infiltration diffusion treatment for enrichment. Also, the heat treatment may be performed in a special process for heat treatment in a magnetic field.

The temperature at which a predetermined magnetic field is applied to the steel sheet (the heat treatment temperature in the magnetic field) may be lower than the Curie temperature. If the heat treatment temperature in the magnetic field is equal to or higher than the Curie temperature, the steel sheet does not show ferromagnetism, and there is no effect of applying the magnetic field. Also, preferably 40
If the heat treatment in a magnetic field is performed at 0 ° C. or more and 650 ° C. or less, the effect of the heat treatment in a magnetic field becomes more remarkable.

The nature of the magnetic field is the most significant feature of the present invention, and the applied magnetic field is an alternating magnetic field. The heat treatment in such an alternating magnetic field has the effect of cooling while moving the magnetic domains of the silicon steel sheet. During the processing, the domain wall (180-degree domain wall) having a low energy required for movement actively moves and is required for movement. High energy domain walls (90
Are cooled without moving. The silicon steel sheet that has been subjected to such a process has a specific magnetic domain structure, and as a result, each property of iron loss and magnetostriction is improved. The AC waveform for obtaining such an effect may be any of a sine wave, a triangular wave, and a square wave, and may be a half wave of each waveform.

The alternating magnetic field is a magnetic field that vibrates periodically at a frequency of 0.5 Hz or more. When the frequency is less than 0.5 Hz, the speed of the domain wall moving during cooling is too slow, so that there is no effect. Further, the frequency is preferably set to 1 kHz or less. At a frequency exceeding 1 kHz, the voltage applied to the magnetic field applying coil becomes extremely large, and the loss in the steel sheet becomes large, so that it is not practical.

It is necessary that the magnitude of the applied magnetic field, that is, the effective value of the strength of the alternating magnetic field be 40 A / m or more as an effective magnetic field in which the demagnetizing field is corrected. Effective magnetic field is 4
If it is less than 0 A / m, the effect of applying a magnetic field cannot be sufficiently obtained.
On the other hand, as the strength of the magnetic field increases, the respective characteristics of magnetostriction and iron loss improve, but the effect is almost saturated at about 2400 A / m. Causes an increase in cost burden. Therefore, the magnitude of the effective magnetic field is preferably set to 2400 A / m or less.

The steel sheet to which the magnetic field has been applied as described above is cooled to 400 ° C. or lower in the magnetic field.
Unless cooled to 400 ° C. or lower in a magnetic field, the effect of the heat treatment in a magnetic field cannot be sufficiently obtained. Further, by cooling to preferably 300 ° C. or lower, the effect of the heat treatment in a magnetic field becomes more remarkable.

The atmosphere for the heat treatment in a magnetic field is not particularly limited as long as it is a non-oxidizing atmosphere. However, since the steel sheet is already coated with an insulating film or the like, the method of the present invention is carried out in a heat treatment that also serves as baking. In this case, the atmosphere does not need to be strictly a non-oxidizing atmosphere, and may be an atmosphere having a high oxygen concentration to some extent.

Next, the composition of the silicon steel sheet subjected to the heat treatment in the magnetic field will be described. The silicon steel sheet targeted by the present invention is a silicon steel sheet containing 1 to 10% by weight of Si, and the properties of magnetostriction and iron loss are significantly improved by heat-treating such a silicon steel sheet in a magnetic field as described above. In addition, magnetic properties such as magnetic permeability are improved. 1 wt% Si content
If it is less than the above, the effect of the heat treatment in the magnetic field is not sufficiently exhibited.
If the content of Si exceeds 10 wt%, the saturation magnetic flux density is remarkably reduced, so that it is not suitable as an electromagnetic steel sheet.

In particular, in the case of a so-called high silicon steel sheet having a Si content of 4 to 10 wt%, the effect of the heat treatment in a magnetic field is remarkably exhibited. Such a high silicon steel sheet has the magnetostriction of zero when the Si content is about 6.5 wt% and exhibits the best soft magnetism. Therefore, the effect of heat treatment in a magnetic field for further improving such characteristics is very important in practical use. Note that a part of Si can be replaced with Al. In this case, Si + Sol. Al is 4 to 10% by weight.

Next, preferred contents of other elements will be described. C is an element harmful to soft magnetic properties,
When C exceeds 0.01 wt%, a so-called aging deterioration phenomenon occurs in which the soft magnetic properties deteriorate with time. Therefore, C is 0.
01 wt% or less. There is no particular limitation on the lower limit of C, but from the viewpoint of smelting, about 0.0005 wt% is a practical lower limit. Mn combines with S to form MnS,
It works to improve hot workability in the slab stage. However, if Mn exceeds 0.5% by weight, the saturation magnetic flux density is greatly reduced, which is not appropriate. Therefore, Mn is 0.5
wt% or less. There is no particular lower limit on Mn, but from the viewpoint of smelting, about 0.005 wt% is a practical lower limit.

P is an element that degrades soft magnetic characteristics,
The content is preferably as low as possible. If the economic efficiency and P are 0.01 wt% or less, the adverse effect is substantially negligibly small.
wt% or less. There is no particular lower limit for P, but from the viewpoint of smelting, about 0.001 wt% is a practical lower limit. S is an element that increases brittleness during hot rolling and also degrades soft magnetic properties. Therefore, the content of S is preferably as low as possible. Since the economic effect and the adverse effect can be substantially ignored if S is 0.01 wt% or less, S is set to 0.01 wt% or less. There is no particular lower limit for S, but from the viewpoint of smelting, about 0.0001 wt% is a practical lower limit.

Al has the effect of cleaning the steel by deoxidation, increases the electrical resistance and affects the magnetic properties. In steel to which 1 to 10 wt% of Si is added, magnetic properties are improved by Si, and Al only has to deoxidize the steel. Al is set to 0.2 wt% or less. Note that Sol. There is no particular limitation on the lower limit of Al, but from the viewpoint of smelting, about 0.0005 wt% is a practical lower limit. On the other hand, a part of Si was dissolved in Sol. When replacing with Al, as described above, 4 to 10 watts of Si + Al
t%.

N is an element that degrades soft magnetic characteristics.
Since the magnetic properties also change with time due to aging, the content is preferably as low as possible. N is set to 0.01 wt% or less because the economic effect and the adverse effect can be substantially ignored if N is 0.01 wt% or less.
There is no particular limitation on the lower limit of N, but from the viewpoint of smelting, about 0.0005 wt% is a substantial lower limit. O is an element that deteriorates the soft magnetic properties, and its content is preferably as low as possible. Economy and O 0.02
If it is less than wt%, the adverse effect can be substantially ignored, so O is made 0.02 wt% or less. There is no particular lower limit on O, but from the viewpoint of smelting, 0.000
About 5 wt% is a practical lower limit.

In addition to the above-mentioned components, there are cases where Cr, Ni, Cu, Sn, Mo and the like are contained as inevitable impurities in the steel. The effect of is not impaired. Silicon steel sheets having these components are rolled, ultra-quenched (rapid solidification),
It may be manufactured by any method of the siliconizing method.

Further, these steel sheets preferably have a thickness of 0.5 mm or less and an average crystal grain size of 20 μm or more and 2.0 mm or less. If the thickness exceeds 0.5 mm, the eddy current loss of the steel plate becomes extremely large. In addition, the average crystal grain size is 20μ.
If it is less than m, the hysteresis loss increases, and it is not suitable for practical use. On the other hand, when the average crystal grain size exceeds 2.0 mm,
The workability of the steel sheet, such as punchability and bendability, deteriorates. For the above reasons, the thickness of the silicon steel sheet is preferably 0.5 mm or less, and the average crystal grain size is preferably 20 μm or more and 2.0 mm or less.

[0030]

【Example】

[Example 1] A sheet thickness of 0.30 mm having the chemical components shown in Table 1
Was manufactured by a siliconizing method and a rolling method. Samples of 3 mx 30 mm were collected from these steel plates, and
The sample was placed in a furnace having a magnetic field application coil having a length of 1 m as shown in Fig. 4 and heat-treated in a magnetic field while moving at a speed of 0.25 cm / sec. The application of the magnetic field to the sample was started during the cooling during the heat treatment. At this time, the temperature at the start of the application of the magnetic field is T
₁ (° C), and the temperature at the end of applying the magnetic field is T
₂ (° C). In this embodiment, T ₁ , T ₂ , heat treatment in a magnetic field under different conditions for the type, frequency, waveform, strength of the magnetic field, etc. of the magnetic field, an Epstein test piece is collected from the center of the processed sample, An AC magnetization test was performed to measure iron loss, and magnetostriction was measured by an optical magnetostriction measuring instrument. The results are shown in Tables 2 and 3 together with the heat treatment conditions in a magnetic field.

According to Tables 2 and 3, it is found that the values of magnetostriction and iron loss are improved by performing the heat treatment in a magnetic field under the conditions specified by the present invention. This effect can be obtained irrespective of the type of AC waveform, and the greater the strength of the applied magnetic field, the smaller the iron loss and magnetostriction. However, 24
In the range of 00 to 4000 A / m, both the magnetostriction and the iron loss tend to slightly decrease, but the change is small in spite of increasing the strength of the magnetic field.

[Embodiment 2] Using equipment for a baking process in a coating line of an insulating film as shown in FIG.
Heat treatment in a magnetic field was performed. In this example, a high silicon steel strip having a chemical composition shown in Table 1 and having a thickness of 0.30 mm was manufactured by a siliconizing method, and this was slit to a width of 80 mm and used as a sample. By adjusting the temperature of the baking furnace so that the temperature of the steel strip at the point where magnetic field application is started is in the range of 500 ° C. to 550 ° C. and adjusting the flow rate of air in the air cooling device at the baking furnace outlet, The temperature at the place where the magnetic field application was completed after leaving the baking furnace was set to 300 ° C. In this example, a heat treatment in a magnetic field was performed in which the type and strength of the magnetic field were changed. After cutting the processed sample and laminating it in a transformer shape by the right-angled butting method as shown in FIG. did. 1kHz, 1T
The noise value at the time of excitation was measured. The measurement was 30 dB (A
Scale) in the acoustic laboratory, and 1
Noise at a point separated by 00 mm was measured with a sound level meter (A scale). Table 4 shows the results together with the heat treatment conditions in a magnetic field.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

According to the present invention described above, it is possible to obtain a silicon steel sheet having excellent magnetostriction and iron loss characteristics and low noise when used as a transformer, and the effect is particularly remarkable in a high silicon steel sheet. It is. Further, even in a silicon steel sheet in which the Si content varies in the sheet width direction, excellent magnetostriction,
Iron loss characteristics can be obtained stably.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an apparatus used in Example 1.

FIG. 2 is an explanatory view showing an apparatus used in Example 2.

FIG. 3 is a perspective view showing a transformer for noise test constituted by a sample of Example 3.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C21D 9/46 501 C21D 1/04 H01F 1/16 C22C 38/00-38/60

Claims (6)

(57) [Claims] (1) It is manufactured by a rolling method or a rapid solidification method.
After permeation and diffusion treatment of silicon by wet silicon steel or siliconizing method
A silicon steel sheet containing Si: 1 to 10 wt%, in a temperature range lower than the Curie temperature,
A method for heat-treating a silicon steel sheet in a magnetic field, comprising applying an alternating magnetic field having an effective magnetic field of 40 A / m or more and subsequently cooling to 400 ° C. or less in the magnetic field. 2. It is manufactured by a rolling method or a rapid solidification method.
After permeation and diffusion treatment of silicon by wet silicon steel or siliconizing method
A silicon steel sheet having : Si: 1 to 10% by weight;
01 wt% or less, Mn: 0.5 wt% or less, P: 0.0
1 wt% or less, S: 0.01 wt% or less, Sol. A
l: 0.2 wt% or less, N: 0.01 wt% or less, O:
An alternating magnetic field having an effective magnetic field of 40 A / m or more is applied to a high silicon steel sheet containing 0.02 wt% or less in a temperature range lower than the Curie temperature, and then cooled to 400 ° C. or less in the magnetic field. Method for heat treatment of silicon steel sheet in a magnetic field. 3. It is manufactured by a rolling method or a rapid solidification method.
After permeation and diffusion treatment of silicon by wet silicon steel or siliconizing method
An alternating magnetic field having an effective magnetic field of 40 A / m or more is applied to a high silicon steel sheet containing 4 to 10 wt% of Si in a temperature range lower than the Curie temperature, and subsequently 400 ° C. or lower in the magnetic field. A method for heat-treating a silicon steel sheet in a magnetic field, characterized by cooling the silicon steel sheet. 4. Manufactured by a rolling method or a rapid solidification method.
After permeation and diffusion treatment of silicon by wet silicon steel or siliconizing method
A silicon steel sheet having a Si content of 4 to 10% by weight and a C: 0.
01 wt% or less, Mn: 0.5 wt% or less, P: 0.0
1 wt% or less, S: 0.01 wt% or less, Sol. A
l: 0.2 wt% or less, N: 0.01 wt% or less, O:
An alternating magnetic field having an effective magnetic field of 40 A / m or more is applied to a high silicon steel sheet containing 0.02 wt% or less in a temperature range lower than the Curie temperature, and then cooled to 400 ° C. or less in the magnetic field. Method for heat treatment of silicon steel sheet in a magnetic field. 5. It is manufactured by a rolling method or a rapid solidification method.
After permeation and diffusion treatment of silicon by wet silicon steel or siliconizing method
A silicon steel sheet of Si + Sol. Al: 4-10w
An alternating magnetic field having an effective magnetic field of 40 A / m or more is applied to a silicon steel sheet containing t% in a temperature range lower than the Curie temperature, and the magnetic field is subsequently cooled to 400 ° C. or less in the magnetic field. Medium heat treatment method. 6. Manufactured by a rolling method or a rapid solidification method.
After permeation and diffusion treatment of silicon by wet silicon steel or siliconizing method
A silicon steel sheet of Si + Sol. Al: 4-10w
t%, C: 0.01 wt% or less, Mn: 0.5 wt% or less, P: 0.01 wt% or less, S: 0.01 wt% or less, N: 0.01 wt% or less, O: 0.02 wt% or less Characterized in that an alternating magnetic field having an effective magnetic field of 40 A / m or more is applied to a silicon steel sheet containing at least a Curie temperature, and then cooled to 400 ° C. or less in the magnetic field. Method.