KR101395800B1 - Method for refining magnetic domain of steel sheets and oriented electrical steel sheets manufacutred by the same - Google Patents

Method for refining magnetic domain of steel sheets and oriented electrical steel sheets manufacutred by the same Download PDF

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Publication number
KR101395800B1
KR101395800B1 KR1020120138350A KR20120138350A KR101395800B1 KR 101395800 B1 KR101395800 B1 KR 101395800B1 KR 1020120138350 A KR1020120138350 A KR 1020120138350A KR 20120138350 A KR20120138350 A KR 20120138350A KR 101395800 B1 KR101395800 B1 KR 101395800B1
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KR
South Korea
Prior art keywords
steel sheet
heating
electrical steel
laser
electric steel
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KR1020120138350A
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Korean (ko)
Inventor
정유철
권오열
이양석
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주식회사 포스코
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/352—Working by laser beam, e.g. welding, cutting or boring for surface treatment
    • B23K26/354—Working by laser beam, e.g. welding, cutting or boring for surface treatment by melting
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/40—Direct resistance heating
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/42—Induction heating
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D10/00—Modifying the physical properties by methods other than heat treatment or deformation
    • C21D10/005—Modifying the physical properties by methods other than heat treatment or deformation by laser shock processing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1294—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a localized treatment

Abstract

The present invention relates to a method of miniaturizing an electric steel sheet and a directional electric steel sheet produced thereby, characterized in that the lower surface of the electric steel sheet is partially heated before or after tension coating on the electric steel sheet, To form a linear groove on the side and bottom surfaces to form molten byproducts and then removing the molten byproducts formed on the bottom surface by air blowing or suction, And a directional electric steel sheet produced by the method are disclosed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of miniaturizing a magnetic steel sheet,

More particularly, the present invention relates to a method for finishing a magnetic strip of an electric steel sheet by partially heating a lower surface of an electric steel sheet and irradiating a laser beam thereon, and a method for manufacturing To a directional electrical steel sheet.

Generally, when a magnetic material such as a silicon electric steel sheet is magnetized close to saturation, the magnetic wall must overcome pinning, which causes a core loss. The magnetic loss is divided into hysteresis loss, eddy current loss and anomalous loss. Hysteresis loss and eddy current loss depend on the material characteristics, but the abnormal loss can be improved by miniaturizing the magnetic domain. .

In order to improve the magnetic properties of the grain-oriented electrical steel sheet, a method of miniaturizing the magnetic domain is used. As the magnetic domain refining method, there is a method of miniaturization of the magnetic domain by temporary annealing and permanent magnetic microfabrication .

The temporary magnetic microfabrication technique is a domain refinement technique which miniaturizes a magnetic domain by forming a 90 DEG domain in order to minimize self-elastic energy generated by applying a local compressive stress to the surface by thermal energy or mechanical energy. On the other hand, the technique of microminiaturization of the temporal magnetic domain is a laser magnetic domain refining method, a ball scratching method, a plasma or ultrasonic wave magnetic domain refining method according to an energy source for finely domaining.

The permanent magnetic microfabrication method capable of maintaining the iron loss improvement effect even after the heat treatment can be classified into an etching method, a roll method and a laser method. The etching method is a method of forming a groove on the surface of an electrical steel sheet by an electrochemical corrosion reaction in an acid solution Therefore, it is difficult to control the groove shape (groove width, groove depth), and it is difficult to guarantee the iron loss property of the final product because grooves are formed in the intermediate process (before decarburization annealing and high temperature annealing) to produce an electric steel sheet. There is a drawback that it is not environmentally friendly.

In the method of refining permanent magnetic billets by a roll, a groove having a constant width and depth is formed on the surface of the electric steel sheet by a pressing process by processing a projection on the roll, and after the permanent magnetic billet is refined, the electric steel sheet is annealed to cause recrystallization under the groove Which is a technique for miniaturizing a magnetic domain, has a disadvantage in that the stability, reliability and process for machining are complicated.

In addition to the above methods, a technique for miniaturization by laser scribing has been developed. Microscopic fringing by the laser scribing is easier than the method of physically stressing the sample, and the reproducibility is high. In addition, the shape of the scribing pattern and the output power of the laser beam are relatively simple, The production process can be improved.

FIG. 1 is a cross-sectional view of a groove 20 formed by irradiating a general laser beam. Referring to FIG. 1, it can be seen that molten by-products are generated on the side surface and the bottom surface of the groove.

At this time, the molten by-product 22 formed on the side surface contributes to the improvement of the iron loss, but the molten by-product 24 formed on the bottom surface adversely affects the iron loss improvement rate.

Therefore, there is a need for a technique for selectively removing only the molten by-products formed on the bottom surface while leaving the molten by-products formed on the sides as they are.

In order to solve the above problems, the present invention provides a method for finely laminating the magnetic steel plate by partially heating the lower surface of the steel plate before laser irradiation, and a directional electric steel sheet produced thereby.

In one or more embodiments of the present invention, partial heating of the lower surface of the electrical steel sheet before or after the tension coating of the electrical steel sheet is performed is performed in a noncontact manner; Forming a linear groove on the side and bottom surfaces of the electrical steel sheet by irradiating a laser beam to form a molten by-product; And a step of removing the molten by-products formed on the bottom surface by air blowing or suction.

The partial heating is performed in a line or spot type, and the width of the line or spot is 90 to 100% of the width (W) of the bottom surface. However, the width W of the bottom surface is the shortest distance in the rolling direction between the side where the side melting ash and bottom side melting by-product meet.

The laser is a continuous wave laser having a frequency range of 200 Hz to 8.5 kHz, and an irradiation distance (D S ) in the rolling direction of the laser is 3 mm to 30 mm.

The noncontact partial heating may be any one of induction heating, resistance heating, spot heating, and energization heating.

Further, in the embodiment according to the present invention, a directional electrical steel sheet produced by any one of the above methods can be provided.

According to the embodiment of the present invention, it is possible to improve the iron loss of the electrical steel sheet by finely laminating the magnetic strip even by laser irradiation with a low output power by preliminarily heating the bottom surface of the steel strip while irradiating the laser beam.

1 is a cross-sectional view of a groove formed by irradiation of a general laser beam.
2 is a cross-sectional view of a groove formed by using a laser beam after preliminarily heating an electric steel sheet lower surface according to an embodiment of the present invention.
3 is a cross-sectional view of a groove in which molten by-products on the bottom surface are removed by air blowing and suction according to an embodiment of the present invention.
4 is a view showing a groove shape formed on an electric steel plate according to an embodiment of the present invention on an XY plane.
5 is a flowchart illustrating a process of forming a groove according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims. Like reference numerals refer to like elements throughout the specification.

The present invention is characterized in that a laser beam is irradiated on the surface of an electric steel plate 10 before the final tension coating is applied before the completion of the secondary recrystallization so that the lower surface of the electric steel plate 10 is partially heated by a pre- The present invention relates to a magnetic microfabrication technique of a directional electrical steel sheet 10 in which a linear groove 20 from which a by-product of melting is removed is formed to maintain the effect of miniaturization even after heat treatment to reduce iron loss.

FIG. 2 is a cross-sectional view of a groove formed by using a laser beam after preliminarily heating the lower surface of an electric steel sheet according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of a groove formed by the air blowing and suction according to the embodiment of the present invention, Is a cross-sectional view of the groove in the removed state.

2, a laser beam 30 is irradiated on the upper surface of the electrical steel sheet 10 and heated by the non-contact type partial heating means 40 on the lower surface thereof, whereby the side-melting by-products 22 and the bottom- Is formed on the surface of the substrate 20.

In the embodiment of the present invention, the irradiation of the laser beam 30 and the heating by the partial heating means 40 can be performed at the same time, and the laser beam 30 is heated after being preheated by the partial heating means 40 You can also investigate.

At this time, the noncontact partial heating may be performed by any one of induction heating, resistance heating, spot heating or energization heating, and the partial heating may be performed in a line or spot type.

In the embodiment of the present invention, as shown in FIG. 2, the partial heating means 40 is heated to a size corresponding to the bottom surface 14 in the rolling direction of the steel strip 10. That is, the width of the line or spot is limited to 90 to 100% of the width W of the bottom surface 14.

If it is less than 90%, the bottom side melting by-product 24 may not be removed properly. On the other hand, if it exceeds 100%, the bottom side melting by-product 24 as well as the side melting by- The width of the lines or spots in the rolling direction is limited to 90 to 100% of the width W of the bottom surface in the embodiment of the present invention. The width W of the bottom surface is the shortest distance in the rolling direction between the side where the side melting byproduct 22 and bottom side melting by-product 24 meet.

The bottom side melt byproduct 24 in the embodiment of the present invention has been melted by irradiation of the laser beam 30 and then cooled to solidify on the bottom surface 14 of the groove 20 and the side melt by- Is melted by irradiation of the laser beam 30 and then cooled and solidified on the side surface 12 of the groove 20. [

3 is a cross-sectional view of the groove 20 in a state where the bottom side of the melt by-product 24 is removed by air blowing and suction means. It is noted that only the molten by- .

As described above, only the bottom side melting by-product 24 is selectively melted to selectively remove the molten by-products 24 formed on the bottom side.

The electrical steel sheet 10 may be a directional electrical steel sheet, and the directional electrical steel sheet may be a GOSS texture in which the aggregate structure of the electrical steel sheet 10 is {110} < 001 > Or a soft magnetic material having excellent magnetic properties in the rolling direction.

Directional electrical steel sheets have excellent magnetic properties in the rolling direction and are used as iron core materials for transformers, motors, generators and other electronic devices.

Generally, the production of a directional electrical steel sheet is performed by a continuous casting process in which a slab is subjected to hot rolling, preliminary annealing, cold rolling, decarburization annealing, high temperature annealing, planarization annealing, insulation coating, do.

The directional electrical steel sheet to be subjected to the laser irradiation may be an electrical steel sheet after completion of the high temperature annealing process for the recrystallization of the electric steel sheet, coating of the tension coat, completion of the high temperature annealing process, and application of the tension coat.

FIG. 5 is a flowchart illustrating a process of forming a groove 20 according to an embodiment of the present invention. Hereinafter, a method of miniaturization of an electric steel sheet will be described with reference to FIG.

In the method of miniaturizing an electric steel sheet according to an embodiment of the present invention, the lower surface of the electric steel sheet is subjected to partial heating (S100) before or after tension coating on the electric steel sheet (S100), and then a laser beam is irradiated S110) so that side side melt bottoms 22 and bottom side melt side products 24 are formed on the side and bottom sides, respectively. At this time, the partial heating (S100) may be performed simultaneously with the irradiation (S110) of the laser beam or before the irradiation of the laser beam, but the preheating treatment may be performed by partially heating the electric steel plate It is more preferable to irradiate the light emitting layer 30.

In order to obtain the effect of irradiating the laser beam with a low output and low intensity by such pretreatment even in the case of preheating the electric steel plate 10, the laser beam 30 is irradiated immediately after partial heating of the lower surface of the electric steel plate 10, .

In the case of partial heating before the irradiation of the laser beam, the electric steel sheet 10 is preheated by the pre-treatment before irradiation with the laser beam in step S100 before laser irradiation, 20 may be formed.

As described above, the groove 20 is formed with the side melting byproducts 22, and the bottom side melting by-product 24 is formed by the subsequent laser irradiation.

After the side-walled by-products 22 and the bottom-walled by-products 24 are formed as described above, the bottom-walled by-products formed on the bottom surface are selectively removed by air blowing or suction (S120) do. The blowing or suction may be performed individually or simultaneously.

The air blowing means and the suction means are provided near the point where the molten by-product is generated when the laser beam is irradiated, and the molten by-products are removed by air blowing or suction.

In order to form the solidification structure of the molten by-product formed in the groove 20 by the air blowing only on the side surface 12 of the groove, the width of the laser beam in the rolling direction corresponds to the size of the width W of the bottom surface By irradiating a laser beam and thereby blowing the molten metal 24 formed in the groove 20 by injecting air and scattering it out or moving to the side 12 of the groove.

As described above, the molten by-product 24 formed on the bottom surface 14 of the groove 20 can be removed by suction or the like to prevent the solidification portion from being formed on the bottom surface 14 of the groove.

By performing scribing on the surface of the electrical steel sheet by the above process, it is possible to achieve miniaturization of the magnetic ball by laser irradiation with a low output. This is because the electric steel sheet is heated by irradiating the laser to melt the electric steel sheet, so that the laser output can be lowered by irradiating the electric steel sheet without heating the electric steel sheet.

At this time, by performing the partial heating of the line or spot type, it is economical to reduce the cost due to the heating rather than to preheat the entire steel plate.

In the embodiment of the present invention, the frequency of the laser beam is not particularly limited, but the laser is preferably a continuous wave laser having a frequency range of 200 Hz to 8.5 kHz.

If the frequency of the laser beam is within 200 Hz or exceeds 8.5 KHz, the depth of the groove 20 does not change at the same laser output, irradiation distance, and line speed, so that it can not be applied to a high line speed. The frequency of the beam is limited to 200Hz to 8.5kHz. In addition, it is possible to form the grooves 20 by melting by irradiating the laser beam within the above frequency range.

Hereinafter, an electric steel sheet according to the present invention will be described.

4 is a view showing a shape of a groove 20 formed in an electric steel plate 10 according to an embodiment of the present invention on an XY plane where the X direction means the width direction of the electric steel plate 10, Means the rolling direction of the electric steel plate 10. Here, Bw is the groove diameter in the rolling direction of the steel strip, and BL is the groove length in the width direction of the steel strip.

The electrical steel sheet 10 of the embodiment according to the present invention limits the interval D s of the line-shaped grooves 20 to 3 to 30 mm, which is the effect of the heat affected zone (HAZ, heat affected zone) So as to improve the iron loss of the electric steel plate 10 by miniaturizing the magnetic domains.

The continuous wave laser is irradiated so as to be divided into 3 to 6 with respect to the width direction of the electric steel plate 10 so that the linear grooves 20 are divided into 3 to 6 with respect to the width direction of the electric steel plate 10.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

Claims (7)

Partially heating the lower surface of the electrical steel sheet in a noncontact manner before or after applying the tension coating to the electrical steel sheet;
Forming a linear groove on the side and bottom surfaces of the electrical steel sheet by irradiating a laser beam to form a molten by-product; And
And removing the molten by-products formed on the bottom surface by air blowing or suction. The method according to claim 1,
Wherein the partial heating is performed in a line or spot type. 3. The method of claim 2,
Wherein the width of the line or spot is 90 to 100% of the width (W) of the bottom surface.
However, the width W of the bottom surface is the shortest distance in the rolling direction between the side where the side melting ash and bottom side melting by-product meet. The method according to claim 1,
Wherein the laser is a continuous wave laser having a frequency range of 200 Hz to 8.5 kHz. The method according to claim 1,
Wherein the irradiation distance (D S ) of the laser in the rolling direction is 3 mm to 30 mm. The method according to claim 1,
Wherein the noncontact partial heating is a heating method selected from the group consisting of induction heating, resistance heating, spot heating, and energization heating. A directional electrical steel sheet produced by any one of claims 1 to 6.
KR1020120138350A 2012-11-30 2012-11-30 Method for refining magnetic domain of steel sheets and oriented electrical steel sheets manufacutred by the same KR101395800B1 (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101491094B1 (en) * 2012-12-27 2015-02-09 주식회사 포스코 Method for refining magnetic domain of steel sheets and oriented electrical steel sheets manufacutred by the same
KR101693513B1 (en) * 2016-01-22 2017-01-06 주식회사 포스코 Method and apparatus for refining magnetic domains grain-oriented electrical steel
KR101739868B1 (en) * 2016-01-22 2017-05-25 주식회사 포스코 Method and apparatus for refining magnetic domains grain-oriented electrical steel
KR101739865B1 (en) * 2016-01-22 2017-05-25 주식회사 포스코 Method and apparatus for refining magnetic domains grain-oriented electrical steel
WO2017126810A1 (en) * 2016-01-22 2017-07-27 주식회사 포스코 Method and device for miniaturizing magnetic domains of directional electric steel plate
KR20170088244A (en) * 2016-01-22 2017-08-01 주식회사 포스코 Method and apparatus for refining magnetic domains grain-oriented electrical steel
JP2019509394A (en) * 2016-01-22 2019-04-04 ポスコＰｏｓｃｏ Magnetic domain refinement method and apparatus for grain-oriented electrical steel sheet

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KR100345723B1 (en) 1999-12-28 2002-07-27 주식회사 포스코 Method for manufacturing a grain oriented electrical steel sheet having a low magnetostriction and manufacturing apparaturs used therein
KR20110124292A (en) * 2009-03-11 2011-11-16 신닛뽄세이테쯔 카부시키카이샤 Oriented electrical steel sheet and method of producing same
JP2012087332A (en) 2010-10-15 2012-05-10 Nippon Steel Corp Method for producing grain-oriented electromagnetic steel sheet

Patent Citations (3)

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Publication number Priority date Publication date Assignee Title
KR100345723B1 (en) 1999-12-28 2002-07-27 주식회사 포스코 Method for manufacturing a grain oriented electrical steel sheet having a low magnetostriction and manufacturing apparaturs used therein
KR20110124292A (en) * 2009-03-11 2011-11-16 신닛뽄세이테쯔 카부시키카이샤 Oriented electrical steel sheet and method of producing same
JP2012087332A (en) 2010-10-15 2012-05-10 Nippon Steel Corp Method for producing grain-oriented electromagnetic steel sheet

Cited By (19)

* Cited by examiner, † Cited by third party
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KR101491094B1 (en) * 2012-12-27 2015-02-09 주식회사 포스코 Method for refining magnetic domain of steel sheets and oriented electrical steel sheets manufacutred by the same
KR101693513B1 (en) * 2016-01-22 2017-01-06 주식회사 포스코 Method and apparatus for refining magnetic domains grain-oriented electrical steel
KR101739868B1 (en) * 2016-01-22 2017-05-25 주식회사 포스코 Method and apparatus for refining magnetic domains grain-oriented electrical steel
KR101739865B1 (en) * 2016-01-22 2017-05-25 주식회사 포스코 Method and apparatus for refining magnetic domains grain-oriented electrical steel
WO2017126888A1 (en) * 2016-01-22 2017-07-27 주식회사 포스코 Method for refining magnetic domains of grain-oriented electrical steel plates, and apparatus therefor
WO2017126811A1 (en) * 2016-01-22 2017-07-27 주식회사 포스코 Method for refining magnetic domains of grain-oriented electrical steel plates, and apparatus therefor
WO2017126810A1 (en) * 2016-01-22 2017-07-27 주식회사 포스코 Method and device for miniaturizing magnetic domains of directional electric steel plate
KR20170088244A (en) * 2016-01-22 2017-08-01 주식회사 포스코 Method and apparatus for refining magnetic domains grain-oriented electrical steel
CN108495940A (en) * 2016-01-22 2018-09-04 Posco公司 The magnetic domain thinning method and its device of oriented electrical steel
EP3406743A4 (en) * 2016-01-22 2018-11-28 Posco Method for refining magnetic domains of grain-oriented electrical steel plates, and apparatus therefor
JP2019509394A (en) * 2016-01-22 2019-04-04 ポスコＰｏｓｃｏ Magnetic domain refinement method and apparatus for grain-oriented electrical steel sheet
JP2019511630A (en) * 2016-01-22 2019-04-25 ポスコＰｏｓｃｏ Method and apparatus for magnetic domain refinement of grain oriented electrical steel sheet
JP2019511629A (en) * 2016-01-22 2019-04-25 ポスコＰｏｓｃｏ Method and apparatus for magnetic domain refinement of grain oriented electrical steel sheet
JP2019512047A (en) * 2016-01-22 2019-05-09 ポスコＰｏｓｃｏ Magnetic domain refining method and magnetic domain refining apparatus for oriented magnetic steel sheet
US11000920B2 (en) 2016-01-22 2021-05-11 Posco Method and device for magnetic domain refinement of oriented electrical steel plate
US11060163B2 (en) 2016-01-22 2021-07-13 Posco Method for refining magnetic domains of grain-oriented electrical steel plates, and apparatus therefor
US11065720B2 (en) 2016-01-22 2021-07-20 Posco Method for refining magnetic domains of grain-oriented electrical steel plates, and apparatus therefor
US11072838B2 (en) 2016-01-22 2021-07-27 Posco Method and device for magnetic domain refinement of oriented electrical steel plate
KR102466498B1 (en) * 2016-01-22 2022-11-10 주식회사 포스코 Method and apparatus for refining magnetic domains grain-oriented electrical steel

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