JP5896112B2 - Oriented electrical steel sheet, method of manufacturing the same, and transformer - Google Patents

Description

  The present invention relates to a grain-oriented electrical steel sheet having excellent magnetostriction characteristics, a manufacturing method thereof, and a low-noise transformer using the grain-oriented electrical steel sheet.

  In recent years, there has been a strong demand for reduction of noise generated by electromagnetic application devices such as transformers and electric motors due to increasing environmental awareness. Accordingly, directional electromagnetic steel sheets used for iron cores of transformers and electric motors are demanded to be materials having excellent noise characteristics in addition to low iron loss.

As a material factor affecting the noise of the transformer, there is a magnetostriction characteristic of the grain-oriented electrical steel sheet. The above-mentioned “magnetostriction” refers to the rate of expansion and contraction of the steel sheet in the rolling direction when the directional electromagnetic steel sheet is excited with an alternating current (= the amount of expansion and contraction of the steel sheet in the rolling direction / the length of the steel sheet). About 10 ⁻⁶ . Therefore, conventionally, research has been made to reduce noise by reducing the magnitude of magnetostriction.

  In order to reduce magnetostriction, it is most effective to reduce the reflux magnetic domain. Here, the “return magnetic domain” means a magnetic domain in which the magnetization vector is oriented in the direction of 90 ° with respect to the magnetic field application direction, and magnetostriction occurs when the magnetization tries to move in a direction parallel to the magnetic field application direction. . This magnetostriction is known to increase as the compressive stress applied to the steel plate increases.

  Therefore, as a method of reducing the reflux magnetic domain, a method of applying a film tension to the grain-oriented electrical steel sheet has been proposed. For example, Non-Patent Document 1 and Patent Document 1 disclose a method of erasing a reflux magnetic domain by applying a film tension to a steel plate. In general, a grain-oriented electrical steel sheet is provided with a forsterite base coating that imparts tensile stress to the steel plate and an insulating coating mainly composed of a phosphate formed thereon. The method intends to improve the magnetostriction characteristics by forming the upper insulating film as a tension-imparting film that applies a tensile stress to the steel sheet. However, these methods have a problem that sufficient effects cannot be obtained when compressive stress is applied to the steel sheet.

  Usually, the iron core of the transformer is cooled by a refrigerant. However, when this cooling is insufficient or the temperature distribution in the iron core becomes uneven at the initial stage of operation of the transformer, the thermal stress is reduced. It is inevitable that it will occur. According to Non-Patent Document 2, when a temperature difference of 5 ° C. occurs, a compressive stress of about 3 to 6 MPa is generated in the <001> direction. This compressive stress reduces magnetostriction characteristics and increases transformer noise. It has been reported. Therefore, development of a grain-oriented electrical steel sheet having low magnetostriction sensitivity to compressive stress is strongly desired.

Japanese Patent Publication No.59-17521

T.A. Nozawa et al, "Relationship between total loss under tenile stress in 3 percent Si-Fe single Crystals and theorientations near (110) 4, IEon. Okazaki et al., “Effect of Temperature Distribution on Magnetostrictive Properties of Oriented Electrical Steel Sheet”, IEEJ Transactions A. Vol. 123 (2003), no. 9, p833-838

  The present invention has been made in view of the above problems of the prior art, and its purpose is to reduce magnetostriction sensitivity to compressive stress and effectively reduce noise generated from iron cores such as transformers. An object of the present invention is to provide a grain-oriented electrical steel sheet having excellent magnetostrictive properties and a low noise transformer using the steel sheet.

  In order to solve the above-mentioned problems, the inventors have conducted detailed studies on various material factors that affect the magnetostriction characteristics of a grain-oriented electrical steel sheet under compressive stress. As a result, in the steel sheet having the tension-imparting coating, the orientation difference angle δ of the crystal orientation of the Goth orientation (110) <001> grains in the steel sheet after secondary recrystallization is a factor that affects the magnetostriction characteristics under compressive stress. I found it important. Here, the above-mentioned misorientation angle δ is a rotation angle around the rolling direction, which is the magnitude of deviation from the ideal Goth orientation grain in the Goth orientation (110) <001> grain of the steel sheet after secondary recrystallization. It is a representation. The inventors have found that a grain-oriented electrical steel sheet having magnetostriction characteristics effective for noise reduction can be obtained by optimizing the steel components and controlling the orientation difference angle δ within an appropriate range. Thus, the present invention has been developed.

That is, the present invention provides Si: 3.0 to 7.0 mass%, Mn: 0.04 to 0.15 mass%, Sb: 0.01 to 0.10 mass%, and Sn: 0.01 to 0.20 mass%. A grain- oriented electrical steel sheet comprising a tension-imparting insulating coating comprising a component composition consisting of Fe and inevitable impurities, and a total of 10 MPa or more of the tensile stress due to the forsterite coating , The average misorientation angle δ of the crystal orientation with the rolling direction as the rotation axis in the Goss orientation {110} <001> grains is 6 ° or less, and a compressive stress of 3.92 MPa is applied in the rolling direction to 50 Hz, 1. It is a grain _- oriented electrical steel sheet having a magnetostriction λpp of 1.7 × 10 ⁻⁶ or less when magnetized at 7T.

  In addition to the above component composition, the grain-oriented electrical steel sheet of the present invention further includes Cr: 0.10 mass% or less, Ni: 0.50 mass% or less, Mo: 0.10 mass% or less, Cu: 0.10 mass% or less, Nb : One or more selected from 0.05 mass% or less and P: 0.05 mass% or less.

In the present invention, C: 0.01-0.10 mass%, Si: 3.0-7.0 mass%, Mn: 0.04-0.15 mass%, N: 0.0030-0.0100 mass% And one or more of Al, S, Se and B as an inhibitor component, Al: 0.01 to 0.030 mass%, S and Se: alone or in total 0.010 to 0.0. A steel slab containing 030 mass%, B: 0.0005 to 0.0030 mass%, the balance being composed of Fe and inevitable impurities, is hot-rolled, and subjected to hot-rolled sheet annealing as necessary, once or after a final thickness by two times or more cold rolling sandwiching the intermediate annealing, primary recrystallization annealing, applying an annealing separating agent, and secondary recrystallization annealing, flattening annealing, tensioning insulating directional to HiNaru a coating In the method for producing a magnetic steel sheet, the steel slab further contains a composite of Sb: 0.01 to 0.10 mass% and Sn: 0.01 to 0.20 mass%, and has a rolling reduction of 84 at a temperature of 150 to 250 ° C. The final cold rolling of ˜90%, the in-furnace tension in flattening annealing is set to 10 MPa or less, and the total tensile stress applied by the forsterite coating and the tension-imparting insulating coating is set to 10 MPa or more, so that the Goth orientation {110} When the average orientation difference angle δ of the crystal orientation with the rolling direction of the <001> grains as the rotation axis is 6 ° or less, and a compressive stress of 3.92 MPa is applied in the rolling direction and magnetized at 50 Hz and 1.7 T The grain _- oriented electrical steel sheet having a magnetostriction λ _p-p of 1.7 × 10 ⁻⁶ or less is obtained .

Moreover, this invention contains C: 0.01-0.10 mass%, Si: 3.0-7.0mass%, Mn: 0.04-0.15mass % , and Al: 0.0100mass% Below, N: 0.0050 mass% or less, S: 0.0050 mass% or less, Se: 0.0050 mass% or less, B: 0.0010 mass% or less, with the balance being a component composition of Fe and inevitable impurities The slab is hot-rolled, hot-rolled sheet annealing is performed as necessary, and cold rolling is performed once or two times sandwiching the intermediate annealing to the final sheet thickness, followed by primary recrystallization annealing and annealing separation agent is applied, secondary recrystallization annealing, flattening annealing, in the manufacturing method of the grain-oriented electrical steel sheet which HiNaru tensioning insulating coating, the steel slab further, Sb: 0.01~0.10mass% And Sn : The 0.01～0.20Mass% containing composite, rolling reduction at a temperature of 150 to 250 ° C. is facilities the rolled 84-90% of the final cooling, the following 10MPa furnace tension in flattening annealing, folders By setting the total tensile stress imparted by the stellite coating and the tension-imparting insulating coating to 10 MPa or more, the average misorientation angle δ of the crystal orientation with the rolling direction in the Goss orientation {110} <001> grains as the rotation axis is 6 °. A grain _- oriented electrical steel sheet having a magnetostriction λ _p-p of 1.7 × 10 ⁻⁶ or less when applied with a compressive stress of 3.92 MPa in the rolling direction and magnetized at 50 Hz and 1.7 T is obtained. It is a manufacturing method of the grain-oriented electrical steel sheet characterized by this.

  In addition to the above component composition, the steel slab in the grain-oriented electrical steel sheet manufacturing method of the present invention further includes Cr: 0.10 mass% or less, Ni: 0.50 mass% or less, Mo: 0.10 mass% or less, Cu: It is characterized by containing one or more selected from 0.10 mass% or less, Nb: 0.05 mass% or less, and P: 0.05 mass% or less.

  Moreover, this invention is a transformer characterized by using the iron core which laminated | stacked the grain-oriented electrical steel sheet as described above.

  According to the present invention, a grain-oriented electrical steel sheet having excellent magnetostriction characteristics can be provided, and a low-noise transformer can be stably manufactured.

It is a graph which shows the relationship between magnetostriction (lambda) _pp under a compressive stress, and the noise of a transformer. It is a graph which shows the relationship between the average orientation difference angle (delta) of a grain-oriented electrical steel sheet, and the magnetostriction (lambda) _pp under compressive stress. It is a graph which shows the influence of the cold rolling reduction ratio on the average orientation difference angle (delta) of a grain-oriented electrical steel sheet.

First, an experiment that triggered the development of the present invention will be described.
<Experiment 1>
C: 0.070 mass%, Si: 3.3 mass%, Mn: 0.06 mass%, Al: 0.02 mass%, N: 0.008 mass%, Se: 0.02 mass%, and further, Sb : Steel mass slab having 0.05 to 5 mass% and / or Sn: 0.05 mass% and having A to C 3 kinds of composition shown in Table 1 is heated to 1420 ° C and hot-rolled to obtain a thickness of 1.6. A hot-rolled sheet having a thickness of ˜3.3 mm was subjected to hot-rolled sheet annealing at 1100 ° C. × 30 seconds, followed by final cold rolling to obtain a cold-rolled sheet having a thickness of 0.29 mm. In the final cold rolling in the cold rolling, the steel plate temperature was raised to 220 ° C. by processing heat generation. Further, the reduction ratio of the final cold rolling was changed in the range of 82 to 91% depending on the difference in the material plate thickness.

Next, in a wet hydrogen atmosphere with a dew point of 60 ° C., after subjecting to primary recrystallization annealing also serving as decarburization at 840 ° C. for 120 seconds, an annealing separator mainly composed of MgO is applied to the steel sheet surface and dried. After that, the temperature is raised to 1000 ° C. in a dry (N ₂ + H ₂ ) mixed atmosphere to perform secondary recrystallization, and then purified at a temperature of 1150 ° C. or higher for 20 hours in a dry H ₂ atmosphere. Finish annealing was performed. Next, after removing the unreacted annealing separator from the surface of the steel sheet after the finish annealing, a coating liquid composed of 50 mass% colloidal silica and magnesium phosphate was applied so that the double-sided area weight was 10 g / m ² . While applying tension, planarization annealing was performed at a temperature of 840 ° C. to form a tension-applying coating film to obtain a product plate.

From the product plate thus obtained, a test piece of length: 300 mm × width: 100 mm was cut out with the rolling direction as the length direction, and the rolling direction in the Goss orientation (110) <001> grains after secondary recrystallization was determined. The average misorientation angle δ of the crystal orientation as the rotation axis was measured by the X-ray Laue method.
Further, the magnetostriction λ _p-p when magnetized at 50 Hz and 1.7 T with a compressive stress of 3.92 MPa applied in the rolling direction of the steel sheet was measured with a laser displacement meter.
Furthermore, a laminated iron core was assembled using the product plate, a 400 kVA transformer was produced, and noise when excited at 1.7 T and 50 Hz was measured.

FIG. 1 shows the relationship between magnetostriction λ _p-p and transformer noise under a compressive stress of 3.92 MPa. From this figure, it is possible to reduce the noise of the transformer by reducing the magnetostriction λp _-p, and it is difficult to reduce the noise with the steel A added with Sb alone or the steel B added with Sn alone. In Steel C in which Sn and Sn are added in combination, a low noise of 50 dB or less can be realized in a region where the magnetostriction λ _p-p is 1.7 × 10 ⁻⁶ or less. Therefore, in order to reduce magnetostriction and noise, It can be seen that the combined addition of Sb and Sn is essential.

FIG. 2 is a graph showing the influence of the average misorientation angle δ of the steel sheet after secondary recrystallization on the magnetostriction λ _p-p under a compressive stress of 3.92 MPa. From this figure, the smaller the average misorientation angle δ, the smaller the magnetostriction λ _p-p , and in the steel C to which Sb and Sn are added in combination, the magnetostriction λ _p-p is 1.7 × 10 ⁻⁶ or less. In order to achieve this, it is understood that the average misorientation angle δ needs to be suppressed to about 6 ° or less.

  FIG. 3 shows the effect of the final cold rolling reduction ratio on the average misorientation angle δ of the steel sheet after secondary recrystallization. From this figure, there is an optimum cold rolling reduction range for reducing the average misorientation angle δ, and in the case of steel C to which Sb and Sn are added in combination, the misorientation angle δ is set to 6 ° or less. Therefore, it is necessary to control the cold rolling reduction ratio in the range of 84 to 90%, and in order to make the misorientation angle δ 4 ° or less, the cold rolling reduction ratio is set in the range of 85 to 89%. Furthermore, it can be seen that in order to make the misorientation angle δ 3 ° or less, it is necessary to control the cold rolling reduction ratio in the range of 86 to 98%.

  Here, the reason why the average misorientation angle δ is greatly reduced in the steel sheet to which Sb and Sn are added in combination is that the effect of Sb that tends to segregate on the surface and Sn that tends to segregate on the grain boundary will be described later. This is thought to be due to the improvement in the primary recrystallization texture and the increase in the degree of integration of the secondary recrystallization orientation in the ideal Goth orientation, coupled with the effect of the steel plate temperature increase after the final cold rolling.

  In addition, Sb and Sn also have an effect of increasing the steel strength in the hot, so that the elongation of the steel sheet in the flattening annealing is suppressed, and damage to the base film (forsterite film) during shape correction is reduced. It is also conceivable that the tensile stress due to the undercoat is strengthened and the deterioration of magnetostrictive properties due to compressive stress is suppressed.

That is, in the steel sheet to which Sb and Sn are added in combination, the effect of improving the magnetostriction characteristics due to the decrease in the misorientation angle δ of the secondary recrystallized grains and the tensile stress strengthening effect of the undercoat are effectively combined. Thus, it is considered that the absolute value (λ _p−p ) of the magnetostriction and the harmonic component of the magnetostrictive waveform are reduced, and the noise reduction of the transformer is achieved. In particular, since the harmonic component increases with an increase in the reflux magnetic domain, the enhancement of the film tension that suppresses the generation of the reflux magnetic domain is effective in reducing the harmonic component.

<Experiment 2>
C: 0.072 mass%, Si: 3.4 mass%, Mn: 0.07 mass%, Al: 0.02 mass%, N: 0.009 mass%, Se: 0.02 mass%, Sb: 0.04 mass% and Sn : A steel slab containing 0.06 mass% and the balance being composed of Fe and inevitable impurities, heated to 1420 ° C., and then hot-rolled to a hot-rolled sheet having a thickness of 2.4 mm, 1120 ° C. × After hot-rolled sheet annealing for 30 seconds, it was cold-rolled to obtain a cold-rolled sheet having a final sheet thickness of 0.27 mm. In the final cold rolling of the cold rolling described above, the cold rolling reduction ratio is set to 88.8%, and the steel sheet temperature after rolling is increased to various temperatures shown in Table 2 by controlling the rolling speed and by heat generated by processing. I let you.

Next, in a wet hydrogen atmosphere with a dew point of 60 ° C., after performing primary recrystallization annealing that also serves as decarburization at 840 ° C. for 120 seconds, an annealing separator mainly composed of MgO is applied to the steel sheet surface and dried. Thereafter, the temperature is raised to 1000 ° C. in a dry (N ₂ + H ₂ ) mixed atmosphere and subjected to secondary recrystallization, and then the finish annealing is performed at a temperature of 1150 ° C. or higher for 20 hours in a dry H ₂ atmosphere for purification treatment. Was given. Next, after removing the unreacted annealing separator from the surface of the steel sheet after the finish annealing, a coating liquid composed of 50 mass% colloidal silica and magnesium phosphate is applied so that the double-sided weight is 10 g / m ^2, and a tension of 9 MPa A flattening annealing was performed at a temperature of 840 ° C. while applying a tension to form a tension-imparting coating, thereby obtaining a product plate.

From the product plate thus obtained, a test piece of length: 300 mm × width: 100 mm was cut out with the rolling direction as the length direction, and the rolling direction in the Goss orientation (110) <001> grains after secondary recrystallization was determined. The average misorientation angle δ of the crystal orientation as the rotation axis was measured by the X-ray Laue method.
Further, the magnetostriction λ _p-p when magnetized at 50 Hz and 1.7 T with a compressive stress of 3.92 MPa applied in the rolling direction of the steel sheet was measured with a laser displacement meter.
Furthermore, a laminated iron core was assembled using the product plate, a 400 kVA transformer was produced, and noise when excited at 1.7 T and 50 Hz was measured.

The results of the experiment are also shown in Table 2. From this result, in order to make magnetostriction (lambda) _pp below 1.7 * 10 < ^-6 >, it turns out that it is necessary to control the steel plate temperature after final cold rolling in the range of 150-250 degreeC. .
The reason why the steel plate temperature needs to be controlled within the above temperature range is that the steel plate temperature improves the primary recrystallization texture through a change in deformation behavior by changing the twisting system, and thus the secondary recrystallization grain. This is because there is an effect of increasing the degree of integration in the Goss direction. This is because if the steel plate temperature after the final cold rolling is less than 150 ° C., the above effect cannot be obtained sufficiently, while if it exceeds 250 ° C., the dislocation recovers and degrades the primary recrystallization texture.
In addition, the steel plate temperature may be raised by working heat generation in the cold rolling as described above, or may be preheated before the final cold rolling, and there is no difference in the effect.

From the result of the above experiment, in order to reduce the noise of the transformer to 50 dB or less, the average misorientation angle δ in the goth orientation grain of the grain-oriented electrical steel sheet used for the iron core is 6 ° or less, and the magnetostriction λ _p-p is It is necessary to set it as 1.7 * 10 <^-6> or less, For that purpose, the steel slab which added Sb and Sn as a raw material is used, and the cold rolling reduction in final cold rolling is made into the range of 84 to 90%. At the same time, the present inventors have newly found that it is necessary to control the steel plate temperature after the final cold rolling to a temperature range of 150 to 250 ° C., thereby completing the present invention.

Next, the grain-oriented electrical steel sheet of the present invention will be described.
As described above, the grain-oriented electrical steel sheet of the present invention improves the magnetostriction characteristics under compressive stress and reduces transformer noise. In the orientation {110} <001> grains, the orientation difference angle δ of the crystal orientation with the rolling direction as the rotation axis needs to be 6 ° or less.

Furthermore, the grain-oriented electrical steel sheet of the present invention has a magnetizing force of 50 Hz and 1.7 T with a compressive stress of 3.92 MPa applied in the rolling direction of the steel sheet in order to reduce the iron loss (noise) of the transformer. It is necessary that the magnetostriction λ _p−p has a magnetostriction characteristic of 1.7 × 10 ⁻⁶ or less.

  In order to further improve the magnetostrictive properties, in addition to limiting the steel component and crystal orientation described above, the insulating coating is used as a tension-imparting coating, and a tensile stress of 10 MPa or more is applied to the steel sheet, It is preferable to remove the residual strain that cancels the applied tensile stress from the steel sheet.

Next, the component composition of the grain-oriented electrical steel sheet (product board) of the present invention will be described.
Si: 3.0 to 7.0 mass%
Si is an essential element necessary for increasing the specific resistance of steel to reduce eddy current loss and reducing iron loss, and for improving magnetostriction characteristics and reducing transformer noise. If the effect is less than 3.0 mass%, it is not sufficient. On the other hand, the addition exceeding 7.0 mass% significantly impairs workability and makes it difficult to produce a steel sheet by rolling. Therefore, Si is set to a range of 3.0 to 7.0 mass%. Preferably it is the range of 3.2-3.7 mass%.

Sb: 0.01 to 0.10 mass%, Sn: 0.01 to 0.20 mass%
As shown in FIGS. 1 and 2, in the grain-oriented electrical steel sheet according to the present invention, the orientation difference angle of the crystal orientation in the Goss orientation {110} <001> grains after secondary recrystallization with the rolling direction as the rotation axis. In a state where δ is reduced and a compressive stress of 3.92 MPa is applied in the steel sheet rolling direction, the magnetostriction λ _p-p when magnetized at 50 Hz and 1.7 T is 1.7 × 10 ⁻⁶ or less, In order to reduce the noise of the transformer, the combined addition of Sb and Sn is essential. When the addition amount of Sb and Sn is less than 0.01 mass%, the above effect cannot be obtained sufficiently. On the other hand, when Sb exceeds 0.10 mass% and Sn exceeds 0.20 mass%, the workability is remarkably lowered. To do. Therefore, Sb and Sn are in the ranges of Sb: 0.01 to 0.10 mass% and Sn: 0.01 to 0.20 mass%, respectively. Preferably, Sb: 0.02 to 0.05 mass%, Sn: 0.03 to 0.10 mass%.

Mn: 0.04 to 0.15 mass%
Mn is an element necessary for ensuring the hot workability of steel, and is also an element that binds to S and Se to form an inhibitor. If the amount of Mn added is less than 0.04 mass%, the effect of improving the hot workability cannot be sufficiently obtained. On the other hand, if it exceeds 0.15 mass%, the magnetostrictive characteristics are lowered and noise is increased. Therefore, Mn is set to a range of 0.04 to 0.15 mass%. Preferably it is the range of 0.05-0.08 mass%.

  Further, the grain-oriented electrical steel sheet of the present invention, in addition to the essential components described above, assists the action of the inhibitor described later and further improves iron loss and magnetic properties, so Cr: 0.10 mass% or less, Ni: Containing one or more selected from 0.50 mass% or less, Mo: 0.10 mass% or less, Cu: 0.10 mass% or less, Nb: 0.05 mass% or less, and P: 0.05 mass% or less Can be made. However, addition of these elements beyond the above range causes embrittlement of the steel and causes cracking and fracture in hot rolling and cold rolling, resulting in a decrease in product yield. preferable.

  In the grain-oriented electrical steel sheet of the present invention, the balance other than the above components is Fe and inevitable impurities. However, the content of other elements is not rejected as long as the effects of the present invention are not adversely affected. However, if C is contained in excess of 0.0050 mass%, the magnetic properties of the product are deteriorated due to magnetic aging, so 0.0050 mass% or less is preferable, and 0.0030 mass% or less is more preferable. preferable.

Next, the manufacturing method of the grain-oriented electrical steel sheet of this invention is demonstrated.
First, the steel slab used as the raw material of the grain-oriented electrical steel sheet of the present invention may be produced according to a conventional method, and there is no particular limitation.
However, as described above, for the steel component, in order to reduce the average misorientation angle δ and improve the magnetostriction characteristics, Sb is 0.01 to 0.10 mass%, Sn is 0.01 to 0.20 mass%. It is necessary to contain it in a composite range.
Further, in order to increase the specific resistance of steel to reduce eddy current loss and reduce iron loss, and to improve magnetostriction characteristics and reduce transformer noise, Si is 3.0 to 7.0 mass. Further, in order to ensure the hot workability of the steel in the range of%, and as an inhibitor forming component, it is necessary to contain Mn in the range of 0.04 to 0.15 mass%.
Furthermore, the steel slab is made of one or more selected from Cr, Ni, Mo, Nb, Cu, and P, with Cr: 0.10 mass% or less, Ni: 0.50 mass% or less, Mo: 0 .10 mass% or less, Cu: 0.10 mass% or less, Nb: 0.05 mass% or less, and P: 0.05 mass% or less are preferable.

Other components contained in the steel slab include C and inhibitor components.
C is preferably contained in the range of 0.01 to 0.10 mass%. That is, C is not only an element useful for improving the crystal structure of a hot-rolled sheet using phase transformation, but also an element useful for generating goth-oriented grains, and at least 0.01 mass%. It is preferable to contain. However, addition exceeding 0.10 mass% may cause insufficient decarburization even if decarburization annealing is performed. Therefore, C is preferably in the range of 0.01 to 0.10 mass%.

  The inhibitor component is essential when an inhibitor is used to develop secondary recrystallization. For example, when AlN is used as an inhibitor, Al: 0.010 to 0.030 mass%, N: 0.0030 to When using MnS and / or MnSe as an inhibitor in the range of 0.0100 mass%, S and Se are used alone or in total in the range of 0.010 to 0.030 mass%, and when BN is used as an inhibitor. Is preferably contained in the range of B: 0.0005 to 0.0030 mass% and N: 0.0030 to 0.0100 mass%. In addition, the said inhibitor utilized for secondary recrystallization may be only 1 type, and may use 2 or more types.

  On the other hand, as in the technique disclosed in Japanese Patent Application Laid-Open No. 2000-129356, when secondary recrystallization is expressed using the effect of suppressing the grain boundary migration of solute nitrogen without using an inhibitor, Al, Inhibitor components such as N, S, Se and B are desirably reduced as much as possible. For example, Al: 0.0100 mass% or less, N: 0.0050 mass% or less, S: 0.0050 mass% or less, Se: 0.0050 mass % Or less and B: It is preferable to reduce to 0.0010 mass% or less.

  Prior to hot rolling, the steel slab adjusted to the above component composition needs to be charged into a heating furnace and reheated to a predetermined temperature. When the steel slab contains an inhibitor component, the reheating temperature is preferably 1300 ° C. or higher in order to completely dissolve the inhibitor component. On the other hand, when the steel slab is a high-purity material in which inhibitor components are reduced as much as possible, the temperature may be 1280 ° C. or lower.

  The subsequent hot rolling may be performed under ordinary conditions, and is not particularly limited. The hot-rolled steel sheet is then preferably subjected to hot-rolled sheet annealing as necessary. This hot-rolled sheet annealing is effective for highly developing a goth structure in the product plate, and in order to obtain the effect, it is preferable to set the annealing temperature in the range of 800 to 1100 ° C.

The hot-rolled sheet that has been hot-rolled or subjected to hot-rolled sheet annealing is then pickled and made into a cold-rolled sheet having a final thickness by cold rolling at least once with one or intermediate annealing in between.
Here, in the production method of the present invention, what is important is that the orientation difference angle δ of the goth-oriented grains of the steel sheet after secondary recrystallization is 6 ° or less, so that the rolling reduction in the final cold rolling is 84 to 90%. It is important to control the steel sheet temperature after the final cold rolling to a temperature range of 150 to 250 ° C.

  After that, the cold-rolled sheet rolled to the final sheet thickness is preferably subjected to primary recrystallization annealing in the temperature range of 800 to 1000 ° C. At this time, when C of the material (steel slab) is higher than 0.005 mass%, in order to prevent magnetic aging in the product plate, the primary recrystallization annealing is performed in a wet atmosphere (oxidizing atmosphere). It is preferable to carry out it also.

  The steel sheet subjected to primary recrystallization annealing is then coated with an annealing separator mainly composed of MgO, dried, wound on a coil, and then finished at a temperature of 1000 ° C. or higher for secondary recrystallization and forsterite film formation. It is preferable to perform annealing. After finishing annealing, after removing the unreacted annealing separator on the surface of the steel sheet, the steel sheet is subjected to flattening annealing that combines the formation of the insulating coating and the correction of the steel plate shape, or after flattening annealing. It is preferable to form a product plate by depositing an insulating coating on the surface of the steel plate.

Here, the insulating coating stably has a magnetostriction λp _-p of 1.7 × 10 ⁻⁶ or less when magnetized at 50 Hz and 1.7 T with a compressive stress of 3.92 MPa applied in the steel sheet rolling direction. Therefore, it is preferable to use a tension-imparting film in which a tensile stress can be imparted to a steel sheet, in which phosphate and colloidal silica are mixed. The tensile stress imparted to the steel sheet by the insulating coating is preferably 10 MPa or more in combination with the tensile stress imparted by the underlying forsterite coating.

  Further, the in-furnace tension applied to the steel plate in the above-described flattening annealing is preferably set to 10 MPa or less which is the minimum necessary tension for shape correction. As a result, damage to the underlying forsterite film is suppressed, and the tensile stress imparted to the steel sheet can be increased, which is advantageous in securing magnetostrictive characteristics under compressive stress.

  A steel slab having the composition shown in Table 3 was heated to the temperature shown in Table 3, and then hot-rolled to a hot-rolled sheet having a thickness of 2.4 mm, and subjected to hot-rolled sheet annealing at 1120 ° C. for 30 seconds. After that, it was cold-rolled to obtain a cold-rolled sheet having a final sheet thickness of 0.27 mm (final cold-rolling reduction ratio: 88.8%). In the final cold rolling of the cold rolling, the steel plate temperature was raised to 220 ° C. by processing heat generation.

Next, after performing primary recrystallization annealing also serving as decarburization at 830 ° C. for 120 seconds in a wet hydrogen atmosphere with a dew point of 62 ° C., an annealing separator mainly composed of MgO is applied to the steel sheet surface, and then dried. Finish annealing after heating to 1000 ° C. in a dry (N ₂ + H ₂ ) mixed atmosphere, followed by secondary recrystallization, and further maintaining in a dry H ₂ atmosphere at a temperature of 1150 ° C. or higher for 20 hours. Was given. The steel sheet after the finish annealing is applied with a coating liquid composed of 50 mass% colloidal silica and magnesium phosphate after removing the unreacted annealing separator on the steel sheet surface so that the double-sided weight is 10 g / m ^2. A flattening annealing was performed at a temperature of 850 ° C. while applying a tension, and a tension-imparting film was formed to obtain a product plate.

From the product plate thus obtained, a test piece of length: 300 mm × width: 100 mm was cut out with the rolling direction as the length direction, and the rolling direction in the Goth orientation (110) <001> grains of the secondary recrystallized grains was determined. The average misorientation angle δ of the crystal orientation as the rotation axis was measured by the X-ray Laue method.
In addition, the magnetostriction λ _p-p when magnetized under the condition of 50 Hz and 1.7 T with a compressive stress of 3.92 MPa applied in the rolling direction of the steel sheet was measured with a laser displacement meter.
Furthermore, a laminated iron core was assembled using the product plate, a 400 kVA transformer was produced, and noise when excited at 1.7 T and 50 Hz was measured.

The results of the above measurements are also shown in Table 3. From Table 3, in the state where the average misorientation angle δ of the crystal orientation with the rolling direction as the rotation axis in the Goss orientation {110} <001> grains is 6 ° or less and a compressive stress of 3.92 MPa is applied in the rolling direction. All steel sheets suitable for the present invention having a magnetostriction λ _p-p of 1.7 × 10 ⁻⁶ or less when magnetized at 50 T, 1.7 T have noise characteristics of the transformer of 50 dB or less and noise characteristics. It turns out that it is excellent.

Claims (6)

Si: 3.0 to 7.0 mass%, Mn: 0.04 to 0.15 mass%, Sb: 0.01 to 0.10 mass% and Sn: 0.01 to 0.20 mass%, the balance being Fe And a grain- oriented electrical steel sheet having a component composition comprising unavoidable impurities and formed by a tension-imparting insulating coating having a total of 10 MPa or more of the tensile stress caused by the forsterite coating , wherein the Goth orientation {110} <001> When the average orientation difference angle δ of the crystal orientation with the rolling direction as the rotation axis is 6 ° or less, and a compressive stress of 3.92 MPa is applied in the rolling direction and magnetized at 50 Hz and 1.7 T A grain _- oriented electrical steel sheet having a magnetostriction λp _-p of 1.7 × 10 ⁻⁶ or less. In addition to the above component composition, Cr: 0.10 mass% or less, Ni: 0.50 mass% or less, Mo: 0.10 mass% or less, Cu: 0.10 mass% or less, Nb: 0.05 mass% or less, and P: The grain-oriented electrical steel sheet according to claim 1, comprising one or more selected from 0.05 mass% or less. C: 0.01-0.10 mass%, Si: 3.0-7.0 mass%, Mn: 0.04-0.15 mass%, N: 0.0030-0.0100 mass%, and an inhibitor As a component, any one or more of Al, S, Se and B is used, Al: 0.01 to 0.030 mass%, S and Se: alone or in total 0.010 to 0.030 mass%, B: 0 A steel slab having a component composition containing 0.05 to 0.0030 mass%, the balance being Fe and inevitable impurities, is hot-rolled, and is subjected to hot-rolled sheet annealing as necessary, and sandwiches one time or intermediate annealing 2 after a final thickness by the above cold rolling once, the direction in which the primary recrystallization annealing, applying an annealing separating agent, secondary recrystallization annealing, to HiNaru flattening annealing, the tensioning insulating coating Of electrical steel sheet In the above, the steel slab further contains Sb: 0.01 to 0.10 mass% and Sn: 0.01 to 0.20 mass%, and finally has a rolling reduction of 84 to 90% at a temperature of 150 to 250 ° C. Cold rolling , the furnace tension in flattening annealing is 10 MPa or less, and the total tensile stress imparted by the forsterite coating and the tension-imparting insulating coating is 10 MPa or more, so that the Goth orientation {110} <001> grains Magnetostriction λ _p− when the average orientation difference angle δ of the crystal orientation with the rolling direction as the rotation axis is 6 ° or less, and a compressive stress of 3.92 MPa is applied in the rolling direction and magnetized at 50 Hz, 1.7 T. _A method for producing a grain-oriented electrical steel sheet, comprising obtaining a grain-oriented electrical steel sheet having _p of 1.7 × 10 ⁻⁶ or less . C: 0.01-0.10 mass%, Si: 3.0-7.0 mass%, Mn: 0.04-0.15 mass % , Al: 0.0100 mass% or less, N: 0.0. 0050 mass% or less, S: 0.0050 mass% or less, Se: 0.0050 mass% or less, B: Reduced to 0.0010 mass% or less, and hot-rolling a steel slab having a composition composed of Fe and inevitable impurities. Then, if necessary, hot-rolled sheet annealing is performed, and cold rolling is performed twice or more with one or more intermediate annealings to obtain a final sheet thickness, followed by primary recrystallization annealing, application of an annealing separator, and following recrystallization annealing, flattening annealing, in the manufacturing method of the grain-oriented electrical steel sheet which HiNaru tensioning insulating coating, the steel slab further, Sb: 0.01~0.10mass% and Sn: 0.01 ~ 0. Containing composite of 20 mass% to facilities the rolling 150 to 250 ° C. The final cold rolling reduction at a temperature of 84 to 90%, the furnace tension not more than 10MPa in flattening annealing, forsterite film and tensioning insulating coating The average tensile difference angle δ of the crystal orientation with the rolling direction of the Goss orientation {110} <001> grains as the rotation axis is 6 ° or less, and the total tensile stress imparted by Directionality characterized by obtaining a grain _- oriented electrical steel sheet having a magnetostriction λpp of 1.7 × 10 ⁻⁶ or less when magnetized at 50 Hz and 1.7 T with a compressive stress of 3.92 MPa applied in the direction. A method for producing electrical steel sheets. In addition to the above component composition, the steel slab further includes Cr: 0.10 mass% or less, Ni: 0.50 mass% or less, Mo: 0.10 mass% or less, Cu: 0.10 mass% or less, Nb: 0.05 mass. % Or less and P: 0.05 mass% or less, 1 type, or 2 or more types chosen from it are contained, The manufacturing method of the grain-oriented electrical steel sheet of Claim 3 or 4 characterized by the above-mentioned. A transformer comprising an iron core in which the grain-oriented electrical steel sheets according to claim 1 or 2 are laminated.

Images