JP2000087139A - Electromagnetic steel sheet and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] (Modified) [Problem] An electrical steel sheet having an excellent balance of magnetic properties in a rolling direction and a direction perpendicular to the rolling direction. SOLUTION: The chemical composition is expressed by weight% and 1.0 ≦ Si <
3.0, Mn: 0 to 0.80, P: 0 to 0.10, C: 0.010, S: 0.030, so
l. Al: 0.020, N: 0.010 or less,
The balance consists of Fe and unavoidable impurities, and has a thickness of 0.
An electromagnetic steel sheet provided with an insulating film containing a resin of 1 to 0.5 μm on at least one surface, wherein the magnetic flux density B _{50 in the} rolling direction is 1.85 T or more, and the Vickers hardness is 100 or more and less than 180. , Electrical steel sheets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrical steel sheet having an excellent balance of magnetic properties in a rolling direction and a direction perpendicular to a rolling direction, and a method for manufacturing the same. In particular, the present invention relates to an electromagnetic steel sheet suitable for a small motor using a split stator core.

[0002]

2. Description of the Related Art In recent years, global environmental problems and energy problems have been highlighted, and there is a demand for improving the efficiency of motors as energy conversion devices. For example, electric vehicles that do not consume fossil fuels and hybrid vehicles that have more than two types of power sources and have improved fuel consumption efficiency are attracting attention. For these, it is desired to use an efficient motor. It is rare.

[0003] The motor efficiency is greatly affected by the performance of the stator core. FIG. 1 shows an example of a shape of an iron core piece (hereinafter, also simply referred to as “integrated type”) which is a core piece constituting a stator iron core (hereinafter, simply referred to as “iron core”) of a motor and is integrally punched from an electromagnetic steel sheet. FIG. In FIG. 1, reference numeral 3 denotes a yoke portion, and reference numeral 4 denotes a teeth portion (teeth portion).
Reference numeral 1 denotes a rotor, reference numeral 2 denotes a winding wound around the teeth, reference numeral 5 schematically shows a flow of magnetic flux inside the iron core, and the magnetic flux passes through the teeth 4 and the yoke 3 to the rotor 1.
Leads to.

[0004] Conventionally, the core of a small motor has been used as an integral type, but recently, in order to improve the motor manufacturing efficiency and performance, an iron core composed of various types of divided core pieces as shown below is used. Hereinafter, it is simply referred to as “split core”)
Has been proposed and its practical use is progressing.

FIG. 2 is a conceptual diagram showing an example of a core piece 6 (T-type split core piece) in which a yoke portion and a tooth portion are arranged in a T-shape. FIG. 3 is a conceptual diagram showing an example of a split-type core piece (I-type split core piece) composed of a ring-shaped yoke portion 7 and an I-shaped tooth portion 8. FIG. 4A is a conceptual diagram showing an example of an iron core piece (expandable split iron core piece) obtained by punching out the yoke portions 9 of a plurality of T-shaped iron core pieces 6 in a straight line. FIG.
(B) is a conceptual diagram of an iron core obtained by applying a winding 2 to a teeth portion 10 of the above-mentioned split-type iron core piece and bending the whole into an annular shape.

[0006] In the conventional integrated iron core, the spacing between adjacent teeth is small, and there is a spatial restriction at the time of winding, so that the density of the winding is reduced and the efficiency of the motor is limited. Productivity during construction was also low.

[0007] On the other hand, in the case of the split core, since the above-described space restriction at the time of winding is small and the winding can be performed without interference of adjacent teeth, the winding density can be reduced as compared with the integrated core. This has the advantage of being able to increase the motor efficiency, which is effective for improving the motor efficiency, and that the winding work is easy, so that the productivity can be improved.

Conventionally, as a material for the core of a motor, especially a small motor, it is inexpensive as compared with a unidirectional magnetic steel sheet.
A non-oriented electrical steel sheet that can be easily punched is used, and a method for improving the magnetic properties of the electrical steel sheet has been disclosed to improve its performance.

Japanese Patent Application Laid-Open No. 5-70833 discloses that the weight%
C: 0.010 to 0.10%, Si: 4.0% or less,
From a non-oriented silicon steel sheet, a steel containing Se and / or S: 0.005 to 0.030% is hot-rolled and cold-rolled, then decarburized and then continuously annealed at 900 to 1200 ° C. Also disclosed is a method for producing an electromagnetic steel sheet having excellent magnetic properties.

Japanese Patent Application Laid-Open No. 7-18334 discloses that
C: 0.010% or less, Si: 1.5 to 4.0%, M
n: 1.0 to 4.0%, S: 0.010% or less, so
l. Al: 0.003 to 0.030%, N: 0.001
A steel slab containing ０．０0.010% is hot-rolled and cold-rolled as it is, or subjected to annealing after hot-rolling and then cold-rolled, and then subjected to continuous annealing for primary recrystallization and 1
A method for producing an electrical steel sheet which is subjected to secondary recrystallization annealing in a 00% hydrogen atmosphere and has an excellent balance of anisotropy of magnetic properties is disclosed.

[0011]

At the teeth of the iron core, magnetic flux concentrates in the longitudinal direction. In the split core, the magnetization directions of all the teeth can be aligned with the rolling direction of the steel sheet having excellent magnetic properties (hereinafter, also simply referred to as “L direction”). It is important that the magnetic properties in the L direction are excellent. Further, when the magnetization direction of the yoke portion of the iron core is aligned with the direction perpendicular to the rolling direction (hereinafter, also simply referred to as “T direction”) where the magnetic characteristics are not good, it is also important that the magnetic characteristics in the T direction are not bad.

In a small motor, the space factor of the iron core has a large influence on the motor efficiency, and it is important to increase the space factor of the iron core. Furthermore, when processing iron core pieces, the core material is punched more frequently than generators and large motors, and the core shape to be punched is more complex than that for transformer cores. It is also necessary that workability is excellent.

The grain-oriented electrical steel sheet has excellent magnetic properties in the L direction. However, the magnetic flux density (B ₅₀ ) at a magnetization force of 5000 A / m in the T direction is extremely inferior to about 1.55 T, the steel content is high, the steel is hard, and forsterite is mainly used between the base steel sheet and the insulating film. Thickness is 3μ
Since there is a hard oxide film having a thickness of 10 to 10 μm, there is a problem that the punching property is not good and the space factor is low.
Further, during the production, decarburization annealing and secondary recrystallization annealing at a high temperature exceeding 1000 ° C. are required, and the production cost is high.
Therefore, the unidirectional magnetic steel sheet is not preferable as a material for a small motor having a split core.

A product obtained by the method disclosed in Japanese Patent Application Laid-Open No. 5-70833 has a high Si content and does not have good punching properties as a core material for a small motor. In addition, in the production thereof, there is a problem that magnetic properties tend to fluctuate greatly because secondary recrystallization is performed by short-time continuous annealing, and the cost is not necessarily low because decarburizing annealing is included as an essential step. Further, in the case of continuous annealing for a short time, fine MnS and / or MnSe precipitates serving as inhibitors may remain in the product and impair magnetic properties.

The product obtained by the method disclosed in Japanese Patent Application Laid-Open No. 7-18334 has a high Si and Mn content, does not have sufficient punching properties as a core material for a small motor, and requires a large amount of an expensive Mn source. In addition, there is also a problem that the production cost is high due to the inclusion in the steel.

As described above, a desirable balance between the magnetic properties in the L direction and the T direction, which is suitable for improving the motor efficiency, particularly for a small motor having a split iron core, and the production efficiency at the time of punching the iron core piece. An electrical steel sheet satisfying the appropriate hardness at the same time as not impairing the hardness has not yet been disclosed.

An object of the present invention is to solve these problems,
The magnetic properties in the L direction are significantly better than conventional non-oriented electrical steel sheets, the magnetic properties in the T direction are better than unidirectional electrical steel sheets, and the punching properties are also excellent. An object of the present invention is to provide an electromagnetic steel sheet suitable for improving the efficiency of a small motor having an iron core and a method for manufacturing the same.

[0018]

Means for Solving the Problems The inventors of the present invention have studied the magnetic characteristics of the magnetic steel sheet with respect to the energy conversion efficiency of a small motor using a split core punched out with the magnetization direction of the teeth aligned with the L direction of the magnetic steel sheet, and other factors. We conducted intensive research on the relationship with desirable steel sheet properties. Furthermore, the research on the manufacturing method of such a steel plate was repeated. As a result, the following new knowledge was obtained. The energy conversion efficiency referred to in the present invention means the ratio of the output energy of the motor to the input energy ([output energy] / [input energy]), and is also simply referred to as “motor efficiency”.

A. During operation of the motor, a magnetic field of a high magnetic field acts on the teeth of the iron core, so that the magnetic properties of the magnetic steel sheet as a material of the iron core at a high magnetic field greatly affect the motor efficiency. For motor using the split core as described above, the motor efficiency when L direction of B ₅₀ of the electromagnetic steel sheet is not less than 1.85T it was markedly improved. Moreover, the effect of improving the motor efficiency when the T direction of B ₅₀ of the core material is less than 1.58T was obtained.

Further, in order to enhance the production efficiency during the punching process with a complicated shape, it is important to keep the hardness of the steel material in an appropriate range, and a hard oxide film which is liable to be generated during the production of magnetic steel sheets. It was also effective in suppressing the noise and optimizing the insulating film.

B. The magnetic properties of the electrical steel sheet are such that during secondary recrystallization annealing, the growth of crystal grains in many directions is suppressed by precipitates called inhibitors, and the
It is greatly influenced by the texture formed by the selective growth of goss crystal grains represented by 0｝ <001>.

In the conventional grain-oriented electrical steel sheet, the inhibitor has an extremely strong effect of inhibiting the growth of crystal grains, and secondary recrystallization with a very high degree of integration in the Goss orientation occurs, so that the magnetic properties in the L direction are significantly improved. However, the magnetic characteristics in the T direction are extremely deteriorated.

On the other hand, a hot-rolled steel sheet having extremely low carbon and a chemical composition in which the content of Si, Al, N, etc. is limited to a specific range is cold-rolled, and then annealed under specific conditions. As described above, it is possible to perform secondary recrystallization annealing with a weaker inhibitor effect than in the case of conventional grain-oriented electrical steel sheets, thereby optimizing the degree of integration of Goss orientation and improving the magnetic property balance in the L and T directions. A desired electromagnetic steel sheet can be easily manufactured. According to this method, it is possible to produce an electromagnetic steel sheet having a low alloy content such as Si and Mn and a preferable hardness.

The present invention has been completed on the basis of these findings, and the gist of the present invention resides in the following electromagnetic steel sheets (1) and (2) and a method for producing the same according to (3).

(1) The chemical composition is% by weight and C: 0.01
0% or less, Si: 1.0% or more and less than 3.0%, Mn:
0 to 0.80%, P: 0 to 0.10%, S: 0.030
% Or less, sol. Al: 0.020% or less, N: 0.0
An electromagnetic steel sheet comprising 10% or less, the balance being Fe and inevitable impurities, and having at least one surface of an insulating film containing a resin having a thickness of 0.1 μm or more and 0.5 μm or less. the magnetic flux density B ₅₀ is more than 1.85 T, 100 or more Vickers hardness, electrical steel sheet and less than 180.

(2) The electromagnetic steel sheet according to the above (1), wherein the thickness of the oxide film between the steel sheet substrate and the insulating film is 1 μm or less.

(3) The chemical composition is% by weight and C: 0.01
0% or less, Si: 1.0 or more and less than 3.0%, Mn: 0
-0.80%, P: 0-0.10%, S: 0.030%
Hereinafter, sol. Al: 0.003 to 0.020%, N:
A steel slab containing 0.001 to 0.010%, the balance being Fe and unavoidable impurities, is hot-rolled, cold-rolled, heated to 860 to 980 ° C., and subjected to primary recrystallization annealing, In an atmosphere having a nitrogen content of 5% by volume or less and a balance of hydrogen gas and / or an inert gas other than nitrogen,
The method for producing an electromagnetic steel sheet according to the above (1) or (2), wherein after heating to 50 ° C. or more and below the Ac1 transformation point and performing secondary recrystallization annealing, an insulating film containing a resin is applied.

[0028]

Embodiments of the present invention will be described below in detail. The percentages of the chemical compositions described below mean% by weight.

Chemical composition of steel: C: Since remaining in the product has an adverse effect on iron loss, it is preferable that the content is as small as possible. If the C content is 0.010% or less, the adverse effect on magnetic properties is small, so the C content is 0.010%.
% As the upper limit. Preferably it is 0.005% or less.

Si: has the effect of increasing the electrical resistance of steel, reducing eddy current loss and reducing iron loss. Si content is 1.0
%, Si is contained in an amount of 1.0% or more because the low iron loss desired by the present invention cannot be obtained. It is preferably at least 1.1%.

On the other hand, when Si is excessively contained, the saturation magnetic flux density is significantly reduced, and it is difficult to reduce the size of the iron core. Further, the steel sheet becomes excessively hard, and the punching property is impaired. Therefore, the Si content is set to less than 3.0%. It is preferably at most 2.8%, more preferably at most 2.0%, even more preferably at most 1.8%.

Mn: Does not significantly affect the secondary recrystallization behavior of the steel of the present invention, and has little effect on the anisotropy of the magnetic properties.
Therefore, Mn is not an essential element, but Mn has an effect of increasing the electrical resistance of the steel, reducing iron loss, hardening the steel and improving the punching property, etc. Is also good. To obtain these effects, Mn is set to 0.0
The content is preferably 5% or more, more preferably more than 0.10%. If the Mn content exceeds 0.8%, the saturation magnetic flux density decreases, and the hardness of the steel material increases, the punching property deteriorates, and the manufacturing cost increases. Therefore, even when Mn is contained, the upper limit is preferably set to 0.80%. More preferably, it is 0.70% or less.

P: P is not an essential element because it has little effect on magnetic properties. However, since it has the effect of hardening steel to improve punchability, it may be contained in an amount of 0.10% or less. If the P content exceeds 0.10%, the steel becomes brittle and easily breaks during cold rolling. Therefore, even when P is contained, the upper limit is preferably set to 0.10%.

S: MnS is combined with Mn to form MnS, which impairs the magnetic properties of steel. Therefore, the smaller the S, the better. Good to do.

Sol. Al: Since it is not an essential element in a magnetic steel sheet as a product, it need not be contained in a magnetic steel sheet as a product. However, sol. Al is an element that forms AlN and (Al, Si) N, which are important inhibitors for causing good secondary recrystallization in the production process, so that sol. It is preferable to contain 0.003% or more of Al. Preferably 0.
005% or more is preferably contained.

Sol. If the Al content exceeds 0.020%, the inhibitor becomes excessive and its dispersion state becomes inappropriate, and secondary recrystallization becomes unstable. Therefore, in steel before rolling, sol. The Al content is preferably set to 0.020% or less. Preferably, the content is 0.018% or less. Sol. Contained in the steel before rolling. Al may decrease during annealing, but may remain in the steel as it is. Therefore, the sol. Al content is 0.
020% or less.

N: Since it is not an essential element in a magnetic steel sheet as a product, it may not be contained in a magnetic steel sheet as a product. However, since N is an element necessary for forming a nitride serving as an inhibitor, it is preferable that the steel before rolling contains 0.001% or more of N. Preferably, the content is 0.002% or more. When the N content exceeds 0.010%, the inhibitor effect is saturated. Therefore, the N content in the steel before rolling is preferably set to 0.010% or less. Preferably, the content is 0.008% or less. N contained in the steel before rolling may decrease during annealing, but may remain in the steel as it is. Therefore, the N content of the magnetic steel sheet as a product is 0.010% or less. The balance is Fe and inevitable impurities.

[0038] Magnetic properties: electrical steel sheet of the present invention, in order to improve the motor efficiency, L direction of the magnetic flux density measured in accordance with the provisions of JIS-C-2550 is a more than 1.85T in B _50. Preferably it is 1.88T or more. T direction of B ₅₀ is more than 1.59T is preferred. More preferably preferably set to more than 1.60T to T direction of B _50.

The motor efficiency mentioned here means a ratio of the output energy of the motor to the input energy ([output energy] / [input energy]). Input energy is calculated from the voltage and current applied to the motor, and output energy is calculated from torque and rotation speed.

Insulating film: The electromagnetic steel sheet of the present invention is generally non-directional on at least one surface of the electromagnetic steel sheet in order to maintain good punching property of the electromagnetic steel sheet and to ensure insulation between the laminated iron core pieces. It is provided with an insulating film containing a known resin and an inorganic component used for a conductive electromagnetic steel sheet. Examples of the insulating film include a film composed of dichromate-boric acid-resin, a film composed of phosphate-resin, and a film composed of silica-resin.

As the resin, an acrylic resin, an acrylic styrene resin, an acrylic silicon resin, a silicon resin, a polyester resin, an epoxy resin, a fluorine resin, or the like can be used. Emulsion type resins are preferred for improving coating properties (roll coating properties).

The composition of the insulating film is as follows: relative to the film weight after drying: inorganic component: 50 to 99%; resin: 1 to 50
%. Pigments such as alumina, zirconia, and titania may be contained as constituent materials other than the above for the insulating film.

If the insulating film is too thin, the insulating property becomes insufficient and the iron loss increases, so the thickness is set to 0.1 μm or more.
If the thickness of the insulating film exceeds 0.5 μm, the space factor decreases, the effective magnetic flux density per sectional area decreases, and the efficiency of the motor decreases. To prevent this, the thickness of the insulating film should be 0.5
μm or less. Preferably it is 0.4 μm or less. The insulating film is preferably provided on both sides of the steel sheet, but may be provided on only one side.

Oxide film: In order to improve the magnetic flux density in the L direction of the magnetic steel sheet of the present invention, <0 in the L direction of the steel sheet before annealing.
Since it is necessary to perform sufficient secondary recrystallization from a nucleus having a 01> axis (Goth nucleus), secondary recrystallization annealing is generally used in the production of non-oriented electrical steel sheets. It is preferable to carry out not the continuous annealing method in which the annealing time is short but the box annealing method in which the steel sheet can be annealed at a high temperature for a long time. Before the box annealing, an annealing separating agent for preventing seizure is applied to the steel sheet, and is removed after the annealing. However, an oxide film that is difficult to remove may remain on the steel sheet surface.

If the oxide film is excessively thick, the continuous punching property is impaired, and the space factor is reduced, and especially the efficiency of a small motor is greatly impaired. Therefore, the thickness of the oxide film is preferably 1 μm or less, more preferably 0.4 μm or less.

Hardness: If the steel plate is too hard, the die will be significantly worn when the iron core is punched, thereby impairing the productivity and deteriorating the fracture surface and flatness of the product. Further, when the deployable iron core is formed into an annular shape, tensile deformation is applied to the outer periphery of the yoke portion, so that the magnetic steel sheet needs to have ductility enough to withstand this. For this reason, the electrical steel sheet of the present invention has a Vickers hardness at a test load of 1 kg (hereinafter simply referred to as “HV”).
) Must be less than 180. Preferably H
V is preferably 175 or less.

If the steel sheet is too soft, the properties of the punched fracture surface deteriorate and the sag increases. In order to avoid this, the hardness (HV) of the steel sheet needs to be 100 or more. Preferably it is 110 or more.

There is a certain relationship between the hardness of the magnetic steel sheet in the annealed state and the chemical composition. For example, Si: 3.3
%, Al: 0.6%, Mn: 0.15%, a general non-oriented electrical steel sheet has an HV of about 200 and a Si content of 3%.
The HV of the contained general-oriented electrical steel sheet is about 190.

Thickness of electromagnetic steel sheet: The thickness of the electromagnetic steel sheet is not particularly limited, but is preferably 0.20 mm or more in order to secure productivity during punching and assembly. More preferably, it is good to be 0.35 mm or more. If the thickness is excessively large, iron loss increases and motor efficiency decreases, so the thickness is preferably 1.0 mm or less, more preferably 0.65 mm or less.

Manufacturing method: The steel sheet of the present invention is preferably manufactured by the following method. Steel having the above chemical composition (provided that sol.
001% or more) is melted in a converter, an electric furnace, etc., and if necessary, continuously cast molten steel subjected to a process such as vacuum degassing, or formed into a steel ingot and then subjected to slab rolling. The slab is formed by hot rolling.

The conditions for the hot rolling are not particularly limited, but when slab heating is performed prior to hot rolling, the temperature is preferably set to 1050 to 1270 ° C. If the temperature of the slab after continuous casting or slab rolling is sufficiently high, hot rolling may be performed directly without performing slab heating.
The finishing temperature in hot rolling is preferably in the range of 700 to 950 ° C, and the winding temperature is preferably in the range of 450 to 800 ° C.

After hot rolling, it is preferable to perform pickling in accordance with a conventional method and then perform cold rolling as it is because of excellent economic efficiency.
Before or after pickling, hot rolled sheet annealing may be performed. The annealing temperature for hot-rolled sheet annealing is 600 ° C. or more and less than 800 ° C. for the box annealing method, and 8 for the continuous annealing method.
It is preferable that the temperature is not lower than 00 ° C and lower than 950 ° C.

For cold rolling, a method of performing cold rolling to a product thickness by one cold rolling (one time cold rolling method) is preferable because it is excellent in economical efficiency, but two cold rolling steps including intermediate annealing are preferable. A method of performing rolling (twice cold rolling) may be used.

Although the rolling reduction of the cold rolling is not particularly limited, if the rolling reduction is less than 65%, the secondary recrystallization may be unstable. If the content is less than 65%, a strong primary recrystallized texture having a {111} orientation suitable for growing crystal grains with a Goss orientation during secondary recrystallization cannot be formed. It is more preferably at least 70%.

If the rolling reduction of the cold rolling exceeds 85%, the Goss orientation of the primary recrystallization texture decreases, and the secondary recrystallization may become unstable. Therefore, the rolling reduction is preferably 85% or less. . It is more preferably at most 83%. The rolling reduction in the case of the double cold rolling method is preferably such that the total rolling reduction from the hot-rolled sheet to the thickness of the final product falls within the above range.

The primary recrystallization annealing temperature is in the range of 860 to 980 ° C. When the annealing temperature is lower than 860 ° C., the primary recrystallized grain size is small, and secondary recrystallization accumulated in the Goss orientation does not occur. Preferably it is 880 ° C or higher. If the annealing temperature exceeds 980 ° C., the primary recrystallization particle size becomes too large, and secondary recrystallization hardly occurs during secondary recrystallization annealing in the next step. Preferably it is 960 ° C or lower.

The annealing time (soaking time) is preferably not shorter than 5 seconds and not longer than 10 minutes. If the annealing time is less than 5 seconds, the primary recrystallized grain size in the steel sheet varies, and stable secondary recrystallization hardly occurs. If the time exceeds 10 minutes, the effect of suppressing the variation in the primary recrystallized grain size is saturated, so that it is economically meaningless.

The heating rate to the primary recrystallization annealing temperature is preferably a rapid heating of 1 ° C./sec or more in order to generate a stable secondary recrystallization in the secondary recrystallization annealing described later. For this purpose, it is preferable to perform annealing by a continuous annealing method.

The secondary recrystallization annealing temperature is at least 750 ° C.
Not more than one transformation point. The purpose of the secondary recrystallization annealing is to obtain a crystal structure having an appropriate degree of Goss orientation accumulation. Therefore, it is important to appropriately control the inhibitor strength in the temperature range where secondary recrystallization occurs.

When the secondary recrystallization annealing temperature is lower than 750 ° C., the inhibitor effect is too strong to cause secondary recrystallization. Preferably it is 800 degreeC or more. If the secondary recrystallization annealing temperature exceeds the Ac1 transformation point, austenite transformation occurs and the inhibitor effect is weakened, so that secondary recrystallization accumulated in the Goss orientation does not occur. Preferably it is 950 ° C. or lower, more preferably 900 ° C. or lower.

The annealing time of the secondary recrystallization annealing is preferably 4 to 100 hours. If the annealing time is less than 4 hours, secondary recrystallization may not be uniform and sufficiently developed over the entire length of the coil. More preferably, it is 8 hours or more. Secondary recrystallization is sufficiently completed within 100 hours. More preferably, it is 80 hours or less.

The atmosphere for the secondary recrystallization annealing is an atmosphere having a nitrogen content of 5% by volume or less and a balance of hydrogen gas and / or an inert gas other than nitrogen. If the nitrogen content exceeds 5% by volume, nitriding from the atmospheric gas to the steel sheet occurs, the inhibitor effect becomes strong, and secondary recrystallization with an excessively high degree of integration in the Goss orientation occurs. In this case,
Although the magnetic properties in the L direction are good, those in the T direction deteriorate and the desired balance of magnetic properties cannot be obtained. Preferably, the nitrogen content is 3% by volume or less.

The atmosphere gas composition other than nitrogen is preferably hydrogen gas. 100% hydrogen gas (a pure hydrogen atmosphere in an industrial sense) may be used. This is because, in the temperature range of 750 to 950 ° C. where secondary recrystallization occurs, the precipitate serving as an inhibitor gradually becomes coarser as the annealing progresses,
This is because a denitrification reaction also occurs, so that a relatively weak inhibitor effect occurs, and secondary recrystallization having an appropriate degree of integration in the Goss orientation occurs. Even in this case, a temperature range of less than 700 ° C. in which nitriding hardly occurs from the viewpoint of economy may be 100% nitrogen gas or a mixed gas of hydrogen and nitrogen.

Prior to the secondary recrystallization annealing, a known annealing separator may be applied to both sides or one side of the steel sheet to prevent seizure between the steel sheets. As a coating method, there are a method of applying in a slurry state, a method of electrostatically applying powder, and the like. Further, an inorganic insulating coating may be applied to one or both surfaces of the steel sheet to have a function of an annealing separator.

In the step after the secondary recrystallization annealing, as in the case of a normal grain-oriented electrical steel sheet, the annealing separator is removed, and if necessary, flattening annealing is performed by a known method. It is preferred that the insulating coating composition containing the inorganic component and the resin is applied by a known method such as a spray method or an immersion method so that the dry film thickness becomes 0.1 to 0.5 μm, and dried by a known method. .

Since the magnetic steel sheet of the present invention has both excellent magnetic properties and punching properties, it is suitable not only for motors having split iron cores but also for transformer materials such as EI iron cores.

[0067]

EXAMPLES (Example 1) Steels having various chemical compositions shown in Table 1 were smelted in a converter, vacuum degassed, adjusted for components, and continuously cast into slabs.

[0068]

[Table 1]

These slabs were hot-rolled to a thickness of 2.
A hot-rolled sheet of 3 mm was formed, pickled, descaled, and then cold-rolled to a thickness of 0.50 mm. Then, heating rate 1
After performing primary recrystallization annealing in which the material is heated to 900 ° C. at 5 ° C./second, held for 30 seconds, and then cooled, an annealing separating agent containing alumina as a main component is applied, and the heating rate is set in an atmosphere of 100% by volume of hydrogen. A second recrystallization annealing was performed in which the temperature was raised to 850 ° C. at 40 ° C./hour, held for 24 hours, and cooled in a furnace.

Thereafter, the annealing separating agent was removed,
Continuous annealing for flattening for 0 second was performed.
No oxide film was observed on the steel sheet surface after continuous annealing. After the flattening annealing, an insulating coating composition containing 80% by weight of magnesium dichromate and boric acid and 20% by weight of an acrylic emulsion resin with respect to the dried film is applied on both sides so that the dry film thickness becomes 0.4 μm. It was applied and dried to obtain electromagnetic steel sheets having various magnetic properties.

The hardness of these magnetic steel sheets was measured, and the B ₅₀ values in the L and T directions were measured in accordance with JIS-C2550. Epstein test pieces were not subjected to stress relief annealing as in general full-process non-oriented electrical steel sheets.

The punching performance of the steel plate was determined by using a punching tool made of SKD11 having a punched piece size of 15 mm square with a clearance of punch and die of 5% of the steel plate thickness and a commercially available punching oil. Is performed at 350 strokes / minute, and the number of punches until the burrow height of the punched piece reaches 50 μm is determined and evaluated according to the following criteria. A case where the number of punches is 1,000,000 or more is judged to be good. did.

◎: 2,000,000 times or more, ：: 1,000,000 times or more, less than 2,000,000 times, ×: Less than 1,000,000 times.

Table 1 shows the performance of the obtained electromagnetic steel sheet. As can be seen from the results shown in Table 1, the steel whose chemical composition satisfies the conditions specified by the present invention had good magnetic properties and excellent punchability.

(Example 2) Of the steels listed in Table 1, S
Steels a and g containing i: 1.8% and Mn: around 0.6%
And slabs of i and i were hot-rolled, pickled, cold-rolled, subjected to primary recrystallization annealing, and coated with an alumina-based annealing separator under the same conditions as described in Example 1. And
Secondary recrystallization annealing was performed. Some coils were subjected to hot rolled sheet annealing before pickling. Then, the annealing separator was removed, and
, Flattening annealing was performed under the same conditions as described above, and the same insulating film composition was applied to various dry film thicknesses and dried to obtain various magnetic steel sheets. The hardness (HV) of each of the obtained magnetic steel sheets was about 145. The magnetic flux densities of these magnetic steel sheets were measured under the same conditions as described in Example 1.

The space factor was measured in accordance with the method specified in JIS-C2550, and 98.5% or more was evaluated as ◎, less than 98.5%, 98.0% or more as ○, and less than 98% as x.

From the various magnetic steel sheets obtained, I-shaped split iron core pieces having the shape shown in FIG. 3 were punched. The teeth were punched out so that their magnetization directions were parallel to the L direction of the magnetic steel sheet. A surface is a motor in which permanent magnets are arranged on a rotor surface of a three-phase four-pole rotor having an output of 750 watts by using a tooth wound and combined with a ring-shaped yoke to produce an I-shaped split core. A magnet type motor was manufactured. As the motor efficiency of these motors, the ratio of the output energy to the input energy at 3600 rpm was investigated, and when this ratio was 84% or more, it was very good (◎), less than 84%, and 83% or more was good (○). , 83%
Less than was evaluated as poor (x). Input energy was calculated from voltage and current applied to the motor, and output energy was calculated from torque and rotation speed. Table 2 shows the obtained results.

[0078]

[Table 2]

As can be seen from the results shown in Table 2, L
Motor using good electromagnetic steel sheet the direction of B ₅₀ and lamination factor had an excellent motor efficiency. In addition, as for the motors of Test Nos. 1 and 6, the drive torque was measured by winding a thread around a pulley having a radius of 10 mm to form a friction brake. As a result, Test No. 1 using an electromagnetic steel sheet satisfying the conditions specified in the present invention was A 3% increase in torque compared to Test No. 6 was observed.

Example 3 Si shown in Table 1 was replaced with 1.4.
%, And a slab of steel h containing 0.17% of Mn was hot-rolled to obtain a hot-rolled coil having a thickness of 2.5 mm. This is pickled, cold-rolled to a thickness of 0.5 mm, hydrogen 75% by volume,
Primary recrystallization annealing was performed for 90 seconds in an atmosphere having a nitrogen content of 25% by volume and a dew point of 50 ° C., and a slurry containing 80% by weight of MgO in terms of dry solid content was adjusted to 5 g / m ^{2 in} terms of dry solid content. After coating and drying to obtain an annealing separator, secondary recrystallization annealing was performed in a hydrogen atmosphere at 880 ° C. for 48 hours. Thereafter, the resultant was washed with 50% and 10% hydrochloric acid to remove the annealing separator floating on the surface. At this point, about 3.2 μm of an oxide film containing forsterite as a main component remained on the surface of the steel sheet. After this, at 40 ° C,
The steel sheet was immersed in 10% hydrofluoric acid, the immersion time was changed variously to dissolve the oxide film, and an electromagnetic steel sheet having oxide films of various thicknesses was obtained. Thereafter, annealing for flattening was performed, and an insulating film having the same composition as described in Example 1 and a dry film thickness of 0.2 μm was applied.

As a conventional example, Si: 3.2%, M:
n: 0.10%, having a thickness of 3.0 μm on both sides having an inorganic coating of 3.0 μm phosphoric acid and colloidal silica.
35 mm commercially available unidirectional electrical steel sheet and Si: 2.0
%, Mn: 0.20%, thickness on both sides: 0.35μ
A commercially available non-oriented electrical steel sheet having a thickness of 0.50 mm and an insulating film made of m-magnesium dichromate-boric acid-acrylic resin was also used as a test material.

Using these magnetic steel sheets, a three-phase four-pole surface magnet type motor having an I-type split iron core similar to that described in Example 2 was manufactured, and under the same conditions as described in Example 2. The motor efficiency was investigated. Further, the punching property was investigated by the same method as described in Example 1. Table 3 shows the obtained results.

[0083]

[Table 3]

As can be seen from the results shown in Table 3, when the thickness of the oxide film was 1.0 μm or less, the punching property and the motor efficiency were good. The commercially available non-oriented electrical steel sheet had poor punching properties, and the commercially available non-oriented electrical steel sheet had poor motor efficiency.

Example 4 The slab of steel g described in Example 1 was heated to 1180 ° C. and hot-rolled at a finishing temperature of 860 ° C. to obtain a hot-rolled steel sheet having a thickness of 2.3 mm. The slab of steel h was heated to 1150 ° C. and hot-rolled at a finishing temperature of 840 ° C. and a winding temperature of 530 ° C. to obtain a hot-rolled sheet having a thickness of 2.3 mm. The Ac1 transformation point was about 1000 ° C. for both steel g and steel h. These hot-rolled steel sheets are pickled and have a thickness of 0.50.
mm, and subjected to primary recrystallization annealing in which continuous annealing was performed at various temperatures. The heating rate to the annealing temperature was set to 10 ° C./sec for steel g and to 15 ° C./sec for steel h. Then, after applying an annealing separator mainly composed of alumina,
It was heated to various temperatures in a hydrogen atmosphere or a hydrogen-nitrogen mixed atmosphere and subjected to secondary recrystallization annealing by a box annealing method. Thereafter, the annealing separator was removed, and continuous annealing was performed for flattening at 820 ° C. for 30 seconds, and an insulating coating was applied. The hardness (HV) of these steel plates is 1 for steel g.
It was around 45 and around 124 for steel h. The magnetic properties of these steel sheets in the L and T directions were measured in the same manner as described in Example 1. Table 4 shows the annealing conditions and the magnetic properties of the obtained steel sheet.

[0086]

[Table 4]

As shown in Table 4, Test Nos. 32, 35, 36, and 37 in which the annealing conditions were within the preferable range.
In Examples 39 and 39, good magnetic properties were obtained. On the other hand, when the conditions of the primary recrystallization annealing or the secondary recrystallization annealing were not in the preferable ranges, the characteristics in the L direction were not good because stable secondary recrystallization did not occur. In Test No. 40 where the N concentration in the secondary recrystallization annealing atmosphere was high,
L direction of B ₅₀ was excellent but not good T direction of B _50.

[0088]

The electromagnetic steel sheet of the present invention is a steel sheet effective for improving the energy conversion efficiency of motors and transformers because the magnetic properties in the L direction are significantly better than conventional non-oriented electrical steel sheets. . Since the electromagnetic steel sheet of the present invention has excellent punching properties, it is possible to improve the efficiency of a small motor having a split iron core with high productivity.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a stator core of a motor, which is an iron core piece integrally punched from an electromagnetic steel plate.

FIG. 2 is a conceptual diagram illustrating an example of a split core piece configured by combining iron pieces in which a yoke portion and a tooth portion are arranged in a T-shape.

FIG. 3 is a conceptual diagram showing an example of a split-type core piece composed of a ring-shaped yoke portion and an I-shaped tooth portion.

FIG. 4A is a conceptual view showing an example of an iron core piece obtained by punching out a plurality of T-shaped iron core pieces by connecting the yokes in a straight line. (B) is a conceptual diagram of an iron core obtained by winding a tooth portion of the above-mentioned split-type split iron core piece and bending the whole into an annular shape.

[Explanation of symbols]

1: rotor, 2: winding, 3: yoke, 4: teeth, 5: magnetic flux, 6: T-shaped iron core, 7: ring-shaped yoke, 8: I-type teeth, 9: T-type Iron core piece, 1
0: Yoke part of T-shaped iron core piece, 11: Teeth part of T-shaped iron core piece.

[Explanation of symbols]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuyo Maeda 4-5-33 Kitahama, Chuo-ku, Osaka City Inside Sumitomo Metal Industries Co., Ltd. (72) Inventor Hiroyoshi Yasu 1850 Minato, Wakayama Sumitomo Metal Industries, Ltd. Wakayama Works

Claims (3)

[Claims] 1. The chemical composition in weight%, C: 0.010%
Hereinafter, Si: 1.0% or more and less than 3.0%, Mn: 0 to 0%
0.80%, P: 0 to 0.10%, S: 0.030% or less, sol. Al: 0.020% or less, N: 0.010
% Or less, the balance being Fe and unavoidable impurities, and having at least one side of an insulating film containing a resin having a thickness of 0.1 μm or more and 0.5 μm or less, wherein the magnetic flux density B ₅₀ is more than 1.85 T,
An electromagnetic steel sheet having a Vickers hardness of 100 or more and less than 180. 2. The magnetic steel sheet according to claim 1, wherein the thickness of the oxide film between the base material of the steel sheet and the insulating film is 1 μm or less. 3. The chemical composition in weight%, C: 0.010%
Hereinafter, Si: 1.0 or more and less than 3.0%, Mn: 0 to 0
0.80%, P: 0 to 0.10%, S: 0.030% or less, sol. Al: 0.003 to 0.020%, N:
A steel slab containing 0.001 to 0.010%, the balance being Fe and unavoidable impurities, is hot-rolled, cold-rolled, heated to 860 to 980 ° C., and subjected to primary recrystallization annealing, In an atmosphere having a nitrogen content of 5% by volume or less and a balance of hydrogen gas and / or an inert gas other than nitrogen,
The method for producing an electromagnetic steel sheet according to claim 1 or 2, wherein an insulating film containing a resin is applied after heating to 50 ° C or higher and below the Ac1 transformation point for secondary recrystallization annealing.