KR20130140213A - Manufacturing method for unidirectional electromagnetic steel sheet - Google Patents

Abstract

After the final finishing annealing step (S07) and the final finishing annealing step (S07), the annealing is performed in a batch furnace in a state in which the steel sheet is wound in a coil shape to form the glass film on the surface of the steel sheet. Insulating film forming process (S08) which forms an insulating film on a glass film, and the laser irradiation process (S09) which irradiates a laser beam from the said insulating film, and performs magnetic domain control, In a laser irradiation process (S09), The laser beam is irradiated to the surface facing the radial direction outer side of the coil at the time of final finishing annealing process S07.

Description

Manufacturing method of unidirectional electrical steel sheet {MANUFACTURING METHOD FOR UNIDIRECTIONAL ELECTROMAGNETIC STEEL SHEET}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a unidirectional electrical steel sheet in which a glass film and an insulating film are formed on a surface of a steel plate branch iron, and are magnetic domain controlled by laser irradiation.

The above-mentioned unidirectional electrical steel sheet is used as a material which comprises the iron core of electric machines, such as a transformer and a rotating machine. In such a unidirectional electrical steel sheet, it is required to reduce the energy loss (iron loss) at the time of magnetizing. Iron loss is classified into eddy current loss and hysteresis loss. In addition, the eddy current loss is classified into a classical eddy current loss and an abnormal eddy current loss.

Here, in order to reduce the classical eddy current loss, the unidirectional electrical steel sheet having a thin plate thickness having an insulating film formed on the plate surface is provided. As the unidirectional electrical steel sheet in which the insulating film was formed, for example, as disclosed in Patent Literature 1, a two-layer structure in which a glass film is formed on the surface of a steel plate base iron, and an insulating film is further formed on the glass film is proposed. have.

In addition, in order to suppress abnormal eddy current loss, for example, as disclosed in Patent Literatures 2 and 3, the laser beam is collected and irradiated from the insulating coating and scanned by scanning in the approximately width direction of the electrical steel sheet. The magnetic domain control method which subdivides a magnetic domain by providing the area | region which has a residual strain periodically in the direction is proposed.

The above-mentioned unidirectional electrical steel sheet is made of a silicon steel slab, for example, and the same procedure as in the hot rolling process → annealing step → cold rolling step → decarburization annealing step → final finish annealing step → insulation film forming step → laser irradiation step. Is manufactured. Here, in the annealing before the final finishing annealing step, an oxide layer mainly composed of silica (SiO ₂ ) is formed on the surface of the steel sheet base iron.

In the final finishing annealing step, heat treatment is performed using a batch furnace in a state where the steel sheet is wound in a coil shape. For this reason, the annealing separator mainly containing magnesia (MgO) is apply | coated to the surface of the steel plate base iron before the final finishing annealing process, in order to prevent the sieve of the steel plate base iron in a final finishing annealing process.

In the final finishing annealing step, the above-described glass film is formed by reacting an oxide layer mainly composed of silica with an annealing separator mainly composed of magnesia.

By the way, in a laser irradiation process, an insulating film is formed on a glass film, a laser beam is irradiated from this insulating film, and magnetic domain control is performed. Here, the scratches may occur in the insulating film and the glass film by irradiation of a laser beam. Here, a flaw means a film damage, such as defect peeling, injury, alteration, and discoloration of these films, and refers to what can be recognized by visual inspection of visual observation and a microscope. In particular, when a scratch is generated in the glass film, steel sheet steel is exposed to the outside, and rust is generated. For this reason, when a flaw generate | occur | produced in the glass film, it was necessary to apply an insulating film again.

In addition, in a unidirectional electrical steel sheet, since many heat processings are performed, a deviation may arise in the interface structure and thickness of a glass film or an insulating film in the longitudinal direction (rolling direction) and the width direction of a steel plate base iron. Therefore, even if the laser irradiation conditions are adjusted, it may be difficult to reliably suppress the occurrence of scratches in the glass coating on the entire steel sheet branch iron.

From such a situation, the manufacturing method of the unidirectional electrical steel sheet which can suppress the generation | occurrence | production of the scratch in the glass film by laser irradiation and can provide a high quality unidirectional electrical steel sheet than the conventional one was calculated | required.

Japanese Patent Application Publication No. 2007-119821 Japanese Patent Application Publication No. 2003-500541 Japanese Patent Publication Hei 06-019112

The manufacturing method of the unidirectional electrical steel sheet of this invention is a manufacturing method of the unidirectional electrical steel plate which has a steel plate branch steel, the glass film formed on the surface of this steel plate base steel, and the insulating film formed on the glass film, and coils the said steel plate base steel Insulation which forms an insulating film on the glass film after the final finishing annealing step of annealing in a batch-type furnace in the state of being wound into a shape to form a glass film on the surface of the steel sheet, and the final finishing annealing step. It has a film forming process and the laser irradiation process which irradiates a laser beam from the said insulating film, and performs magnetic domain control. In the said laser irradiation process, it is the surface which faces radial direction outer side of the coil at the time of the said final finishing annealing process. Is to irradiate a laser beam.

In the final finishing annealing step, heat treatment is performed in a batch furnace in a state where the steel sheet is wound in a coil shape, and a glass film is coated on the surface facing the radially outer side and the surface facing the radially inner side of the coiled steel sheet. Is formed. And in an insulation film formation process, an insulation film is formed on a glass film in the state which unwound the steel plate branch iron wound up in coil shape and plate-shaped. Moreover, in a laser irradiation process, a laser beam is irradiated to a board surface in the state which plated the steel plate base steel in which the glass film and the insulating film were formed in plate shape.

Here, when releasing the sheet steel coil wound in the coil shape and unfolding it into a plate shape, compressive stress acts on the glass film formed on the surface facing the radially outer side of the coil, and tension is applied to the glass film formed on the surface facing the radially inner side of the coil. The stress acts. In addition, the glass coating is weak in tensile stress but strong in compressive stress.

Therefore, in a laser irradiation process, the flaw generate | occur | produces in a glass film by irradiating a laser beam with respect to the radial direction outer side of the coil in the final finishing annealing process, ie, the glass film on which the compressive stress acted. Can be suppressed. Thereby, it is not necessary to form an insulating film again after a laser irradiation process, and the production efficiency of a unidirectional electrical steel sheet can be improved significantly.

According to the present invention for focusing and irradiating a laser beam on a surface facing the radially outer side of the coil in the final finishing annealing step in which the adhesion between the main body (ferrous iron) of the steel sheet and the glass film is not deteriorated, scratches in the glass film Generation can be suppressed reliably, and it becomes possible to provide a high quality unidirectional electrical steel sheet.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the cross section of the unidirectional electrical steel plate manufactured by the manufacturing method of the unidirectional electrical steel sheet which is embodiment of this invention.
2 is a flowchart of a method of manufacturing a unidirectional electrical steel sheet according to an embodiment of the present invention.
It is a schematic explanatory drawing of the decarburization annealing process and annealing separator coating process in FIG.
It is a schematic explanatory drawing of the final finishing annealing process in FIG.
FIG. 5 is a schematic explanatory diagram of an insulating film forming step in FIG. 2. FIG.
6 is a schematic explanatory diagram of a laser irradiation step in FIG. 2.
7 is a diagram illustrating an evaluation result of an example of the present invention.
8 is a diagram illustrating an evaluation result of a comparative example.

EMBODIMENT OF THE INVENTION Below, embodiment of this invention is described with reference to attached drawing.

The unidirectional electrical steel sheet 10 shown in FIG. 1 includes a steel plate branch iron 11 (steel plate), a glass film 12 formed on the surface of the steel plate branch iron 11, and an insulating film formed on the glass film 12. (13) is provided.

The steel plate base iron 11 (branch iron) is comprised from the iron alloy containing Si. In this embodiment, Si; 2.5 mass% or more and 4.0 mass% or less, C; 0.02 mass% or more and 0.10 mass% or less, Mn; 0.05 mass% or more and 0.20 mass% or less, acid-soluble Al; 0.020 mass% or more and 0.040 mass% or less , N; 0.002% by mass or more, 0.012% by mass or less, S; 0.001% by mass or more and 0.010% by mass or less, P: 0.01% by mass or more and 0.04% by mass or less, and the remainder is composed of compositions such as Fe and inevitable impurities.

In addition, the thickness of the steel plate branch iron 11 (ferrous iron) is generally 0.15 mm or more and 0.35 mm or less.

Glass film 12 is, for example, is composed of a composite oxide such as forsterite (Mg ₂ SiO _4), spinel (MgAl ₂ O _4), and cordierite _{(Mg 2 Al 4 Si 5 O} 16) . In addition, the thickness of this glass film 12 is set to about 1 micrometer.

The insulating film 13 is a coating liquid mainly composed of colloidal silica and phosphate (magnesium phosphate, aluminum phosphate, etc.) (for example, Japanese Patent Application Laid-Open No. 48-39338 and Japanese Patent Laid-Open No. 53-28375). In addition, it is comprised by the coating liquid which mixed alumina sol and boric acid (Unexamined-Japanese-Patent No. 6-65754, Unexamined-Japanese-Patent No. 6-65755). In this embodiment, the insulating film 13 is shown about aluminum phosphate, colloidal silica, and chromic anhydride (Unexamined-Japanese-Patent No. 53-28375). In addition, the thickness of this insulating film 13 is set to about 2 micrometers.

And in this unidirectional electrical steel sheet 10, when a laser beam is irradiated from the insulating film 13, residual strain is given to the linear region substantially orthogonal to a rolling direction. The linear region to which the residual strain is applied is formed at predetermined cycles in the rolling direction, and is subdivided in the domain width in the direction substantially perpendicular to the rolling direction in the region in which the magnetization is directed in the rolling direction by being fitted into the two linear regions. do.

Next, the manufacturing method of the unidirectional electrical steel sheet which is this embodiment is demonstrated.

As the manufacturing method of the unidirectional electrical steel sheet which is this embodiment, as shown in the flowchart of FIG. 2, casting process S01, hot rolling process S02, annealing process S03, cold rolling process S04, decarburization annealing process S05, It has an annealing separator application process S06, a final finishing annealing process S07, an insulation film formation process S08, and a laser irradiation process S09.

In casting process S01, molten steel prepared with the above-mentioned composition is supplied to a continuous casting machine, and an ingot is produced continuously.

In hot rolling process S02, the obtained ingot is heated at predetermined temperature (for example, 1150-1400 degreeC), and hot rolling is performed. Thereby, the hot rolled material of thickness 1.8-3.5 mm is produced, for example.

In the annealing step S03, the hot rolled material is subjected to a heat treatment under the conditions of, for example, 750 to 1200 ° C for 30 seconds to 10 minutes.

In cold rolling process S04, after pickling the surface of the hot rolling material after annealing process S03, it cold-rolls. Thereby, the cold rolled material of thickness 0.15-0.35 mm is produced, for example.

In the decarburization annealing step S05, the cold rolled material is subjected to a heat treatment, for example, under conditions of 700 to 900 ° C × 1 to 3 minutes. Here, in the decarburization annealing step S05, as shown in FIG. 3, the cold rolled material wound in a coil shape is taken out into a plate shape and subjected to heat treatment while traveling in the furnace 21. Thereby, the steel plate branch iron 11 is produced. As shown in Fig. 3, the decarburization annealing step S05 forms an oxide layer 15 mainly composed of silica (SiO ₂ ) on the surface of the steel plate base iron 11. In annealing separator application process S06, as shown in the cross-sectional enlarged view of the steel plate enclosed by (circle) of FIG. 3, the annealing separator 16 which mainly uses magnesia (MgO) is apply | coated on the oxide layer 15. FIG.

In the final finishing annealing process S07, as shown in FIG. 4, in the state which wound up the steel plate base steel 11 to which the annealing separator 16 was apply | coated to coil shape, it charges in the batch furnace 22 and heat-processes. do. In addition, the heat processing conditions in this final finishing annealing process S07 are 1100-1300 degreeC * 20 to 24 hours. In this final finishing annealing step S07, the oxide layer 15 mainly composed of silica and the annealing separator 16 mainly composed of magnesia react, and are shown in the cross-sectional enlarged view of the steel sheet surrounded by ○ in FIG. Similarly, the glass film 12 in which the surface of the steel plate base iron 11 is made of forsterite (Mg ₂ SiO ₄ ) is formed.

In insulating film forming process S08, as shown in FIG. 5, the steel plate base iron 11 wound up in coil shape was unwound, and it conveyed to plate shape, and was carried out on the glass film 12 formed in both surfaces of the steel plate base iron 11 An insulation film is apply | coated and baked, and the insulation film 13 is formed. The steel plate branch iron 11 in which the insulating film 13 was formed is wound in a coil shape.

In laser irradiation process S09, as shown in FIG. 6, the steel plate base iron 11 wound up in coil shape was unwound and conveyed in plate shape, and a laser beam is condensed and irradiated toward the single side | surface of the steel plate base iron 11, It scans in the substantially width direction of an electrical steel plate. Thereby, the deformation | transformation of the linear shape which is substantially orthogonal to a rolling direction is given to the surface of the steel plate branch iron 11 at the interval set previously with respect to the rolling direction. At this time, in the final finishing process S07, the laser irradiation apparatus 23 is arrange | positioned so that a laser beam may be irradiated to the surface which faces the radial direction outer side of the coil when charged in the batch type | mold 22. As shown in FIG. The light source and type of the laser are not particularly limited as long as it is a laser light source normally used for magnetic domain control by laser irradiation. In this embodiment, the example using a YAG laser is shown by laser irradiation process S09.

In this way, the glass film 12 and the insulation film 13 are formed on the surface of the steel plate branch iron 11, and the unidirectional electrical steel sheet 10 which is magnetically controlled by laser irradiation is manufactured.

According to the manufacturing method of the unidirectional electrical steel sheet which is this embodiment which has the above structures, in the state of final finishing annealing process S07, in the state which wound up the steel plate base iron 11 to which the annealing separator 16 was apply | coated in coil shape, Since it is charged in the batch furnace 22 and heat-processed, the glass film 12 is formed in the surface which faces the radial direction outer side, and the surface which faces the radial direction inner side of the coil-shaped steel plate 11, respectively.

And in the laser irradiation process S09, the steel plate branch iron 11 wound up in the coil shape is unfolded and conveyed in plate shape, and the surface facing the radial direction outer side of the coil inserted in the batch type | mold 22 in final finishing process S07. The laser beam is irradiated with respect to.

Here, when unwinding the sheet steel 11 wound in the coil shape and unfolding it into plate shape, a compressive stress acts on the glass film 12 formed in the radial direction outer side of the coil, and the surface which faces the coil inner side radially inward. Tensile stress is applied to the glass film 12 formed in the.

In this embodiment, in the laser irradiation step S09, the laser beam is irradiated to the surface on which the glass film 12 on which the compressive stress is applied is formed. The glass film 12 is weak in tensile stress but strong in compressive stress. As a result, the occurrence of scratches on the glass film 12 can be suppressed, and the steel sheet base 11 can be prevented from being exposed to the outside.

Therefore, after laser irradiation process S09, it is not necessary to form the insulating film 13 again. In addition, it is possible to reliably suppress the occurrence of scratches in the glass film 12 without restricting the laser irradiation conditions in the laser irradiation step S09 more than necessary. Therefore, the production efficiency of the unidirectional electrical steel sheet 10 can be improved significantly.

In addition, the glass coating 12 can be provided with a high-quality unidirectional electrical steel sheet 10 with less occurrence of scratches.

Example

Next, the confirmation experiment performed to confirm the effect of this invention is demonstrated. First, Si; 3.0 mass%, C; 0.05 mass%, Mn; 0.1 mass%, acid soluble Al; 0.02 mass%, N; 0.01 mass%, S; 0.01 mass%, P; 0.02 mass%, and the balance was Fe and A slab having a composition such as unavoidable impurities was prepared.

About this slab, hot rolling was performed at 1280 degreeC, and the hot rolling material of thickness 2.3mm was produced.

Next, heat treatment was performed on the hot rolled material under the condition of 1000 ° C for 1 minute. After the pickling treatment was performed after the heat treatment, cold rolling was performed to prepare a cold rolled material having a thickness of 0.23 mm.

About this cold rolling material, decarburization annealing was performed on condition of 800 degreeCx 2 minutes. And the annealing separator which has magnesia as a main component was apply | coated to both surfaces of the cold rolling material after decarburization annealing.

In the state where the cold rolled material to which the annealing separator was applied was wound in a coil shape, charged into a batch furnace, and finally finished annealing was performed under conditions of 1200 ° C for 20 hours. This produced the steel plate branch iron in which the glass film was formed on the surface.

Next, the insulating material which consists of aluminum phosphate was apply | coated and baked (850 degreeC x 1 minute) on the glass film, and the insulating film was formed.

Then, the laser beam was irradiated to the steel sheet base iron on which the insulating film and the glass film were formed, thereby deforming the surface of the steel sheet base iron. The irradiation conditions of the laser beam at this time are the output 200W, the condensation spot shape dl (rolling direction diameter) x dc (width direction diameter) = 100 micrometers x 4000 micrometers of width | variety, scan speed Vc = 16m / s, pitch 4mm It was set as.

In the example of this invention, the laser beam was irradiated to the surface facing radial direction outer side of a coil at the time of final finishing annealing.

In the comparative example, the laser beam was irradiated to the surface facing radially inner side of the coil at the time of final finishing annealing.

Thus, the salt spray test was performed about the unidirectional electrical steel plate which is the example of this invention, and the unidirectional electrical steel plate which is a comparative example, and it evaluated by rust rating. In addition, the rust rating was evaluated according to the JIS K2246 5.34 wet test method by the following five steps according to the incidence rate of the laser irradiation part (visual and image processing).

Passing a rating 5, no rust, and the laser irradiation part cannot be visually confirmed. It cannot be confirmed even under a microscope.

A grade 4 pass, no rust, and a laser irradiation part are confirmed under a microscope. It cannot be confirmed with the naked eye.

The grade 3 pass, no rust generation, and a laser irradiation part can be visually confirmed (the insulating film may be deteriorated or damaged, but the glass film is sound and the insulation is maintained).

Rejection 2 Rejection, Rust occurs, Visually confirms rust discretely.

Rating 1 Failed, there is rust occurrence, and visually confirmed rust continuously.

If the rating is 4 or more, it is not necessary to reapply the insulating film. The evaluation results are shown in FIGS. 7 and 8.

According to the example of this invention, as shown in FIG. 7, green-flat point is set to 4 and 5, and it is confirmed that a scratch does not generate | occur | produce in a glass film.

On the other hand, in a comparative example, as shown in FIG. 8, there exists a point where a green flat point becomes 1, 2, 3. In many places, a flaw generate | occur | produces in a glass film and it is judged that steel plate base iron is exposed.

In addition, in the above-mentioned other glass film or insulating film other than the above embodiment, the occurrence of scratches in the glass film is suppressed by irradiating a laser beam to the surface on which the glass film on which the compressive stress is applied is formed. It was confirmed. Moreover, the generation | occurrence | production of a scratch was investigated using the fiber laser etc. as a laser beam to irradiate, and the same result was obtained as a tendency.

From the above, according to the example of this invention, even if it is the same laser irradiation conditions, it was confirmed that generation | occurrence | production of the scratch in a glass film can be suppressed.

ADVANTAGE OF THE INVENTION According to this invention, the high quality unidirectional electrical steel plate which irradiated the laser beam with respect to the surface in which the glass film on which the compressive stress acts is formed can be suppressed, and the generation | occurrence | production of the scratch in a glass film can be suppressed.

10: unidirectional electrical steel sheet
11: steel sheet iron
12: glass film
13: insulation film
S07: Final Finish Annealing Process
S09: Laser Irradiation Process

Claims (1)

It is a manufacturing method of the unidirectional electrical steel sheet which has a steel plate branch steel, the glass film formed on the surface of this steel plate base steel, and the insulating film formed on the glass film,
A final finishing annealing step of annealing in a batch furnace in a state in which the steel sheet is wound in a coil shape, thereby forming a glass film on the surface of the steel sheet, and
An insulating film forming step of forming an insulating film on the glass film after the final finishing annealing step,
It has a laser irradiation process which irradiates a laser beam from the said insulating film, and performs magnetic domain control,
In the said laser irradiation process, a laser beam is irradiated to the surface which faces the radial direction outer side of the coil at the time of the said final finishing annealing process, The manufacturing method of the unidirectional electrical steel sheet characterized by the above-mentioned.

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