JP3369724B2 - Grain-oriented electrical steel sheet with low iron loss - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low iron loss oriented magnetic steel sheet suitable for use in an iron core of a transformer or other electric equipment. Grain-oriented electrical steel sheets are mainly used as core materials for transformers, and are required to have good magnetic properties. In particular, it is important that the energy loss, that is, the iron loss when used as an iron core is low. [0002] Conventionally, in order to reduce iron loss, the crystal orientation should be more highly aligned with the (110) [001] orientation, the Si content should be increased, thereby increasing the electrical resistance of the steel sheet. Various attempts have been made to reduce impurities and to reduce the thickness of the sheet. As a result, for steel sheets with a thickness of _{0.23 mm} or less, iron loss W _17/50 (magnetic flux density 1.7
T, iron loss value at 50 Hz) is 0.9 W / kg or less. However, no further significant improvement in iron loss can be expected with metallurgical methods. [0003] In recent years, various attempts have been made to artificially subdivide magnetic domains as means for achieving a significant reduction in iron loss. Among them, the method currently being industrialized includes irradiating a laser to the surface of a steel sheet that has been finish-annealed, as disclosed in a method for improving iron loss characteristics of grain-oriented electrical steel sheets of Japanese Patent Publication No. 57-2252. There is a way.
However, although this method is effective in reducing iron loss, it has a disadvantage that iron loss is deteriorated by strain relief annealing, and is not used for wound iron cores that require strain relief annealing. [0004] As a technique for reducing iron loss, which is capable of performing strain relief annealing by improving such a magnetic domain refining method, Japanese Patent Publication No. 62-54873.
The method for producing a low iron loss unidirectional magnetic steel sheet disclosed in Japanese Patent Application Publication No. 2004-214873 includes a method in which an insulating film is locally removed from a finish-annealed steel sheet by laser or mechanical means, and then a film removing portion is pickled or a knife is used. A method in which a linear groove is locally formed by a method such as mechanically directly marking the ground iron, and then a phosphoric acid-based tension imparting coating treatment is applied to fill the groove. No. 53579 discloses a method for producing a low iron loss unidirectional electrical steel sheet.
A method of forming a groove with a depth of more than 5 μm in the base iron part with a load of kgf / mm ² and then performing heat treatment at a temperature of 750 ° C. or more is described in Japanese Patent Publication No. 3-69968. Methods for introducing linear notches in a direction substantially perpendicular to the subsequent rolling direction of the steel sheet have been proposed and disclosed. [0005] The above-mentioned Japanese Patent Publication No. Sho 62-54873
JP, JP-B-62-53579 and JP-B-3-69968
The steel sheets obtained by the method disclosed in Japanese Patent Laid-Open Publication No. H10-150572 have in common that they have linear grooves, and the magnetic domain refinement effect derived from the magnetic poles generated around the grooves is one of the iron loss improvement principles. At present, steel sheets using these methods are industrially produced as magnetic steel sheets capable of performing strain relief annealing. However, these steel sheets cannot be said to have a sufficient magnetic domain segmentation effect because the generation of magnetic poles is limited to the vicinity of the groove, and there is room for improvement in reducing iron loss. [0006] Therefore, an object of the present invention is to propose a grain-oriented electrical steel sheet with further improved magnetic properties, particularly iron loss properties, with respect to a grain-oriented silicon steel sheet having grooves formed on its surface. The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have obtained a steel sheet having a linear groove extending in a direction substantially perpendicular to the rolling direction on the surface. An electromagnetic steel sheet in which crystal grains having a fine particle size exist continuously or discontinuously in a direction perpendicular to the rolling direction in a portion other than the linear grooves, and the width of the region where the fine crystal grains exist is 2 mm or less. However, it was found that they show lower iron loss than ever before,
The present invention has been made. That is, the present invention relates to a grain-oriented electrical steel sheet having a plurality of linear grooves extending on a surface thereof in a direction substantially perpendicular to the rolling direction, wherein the linear grooves have a width of 30 μm or more and 300 μm or more.
m or less, depth of 10 μm or more and 70 μm or less, spacing in the rolling direction
Is 1mm or more and 30mm or less, deviation from the direction perpendicular to the rolling direction.
The deflection angle is within 30 °, and a band-like region composed of a group of fine crystal grains is provided between adjacent grooves.
Has a width of 2 mm or less, a gap in the rolling direction of 1 mm or more and 50 mm or less,
The deviation angle from the direction perpendicular to the rolling direction is within 30 °
Is a low oriented electrical steel sheet iron loss, characterized in that that. Hereinafter, the results of the research on which the present invention is based will be described. Including MnSe and AlN as inhibitors
Si: Intermediate annealing of a hot rolled steel sheet containing 3.3% silicon steel 2
Rolling was performed to a thickness of 0.23 mm by cold rolling each time, and thereafter, the following five types of processes (A) to (E) were performed to obtain various types of magnetic steel sheets. (A) After applying an etching resist by gravure offset printing, a linear groove was formed by electrolytic etching, followed by decarburizing annealing and then final finishing annealing. (B) After performing the same groove forming process as in (A) and performing a resist removing process, 3 g of SnSO ₄ per 1 m ^{2 in} a direction parallel to the groove is applied linearly between the adjacent grooves. Then, the same decarburizing annealing and final finishing annealing as in (A) were performed.
The number of the linear coating portions of SnSO ₄ was one each between the grooves. (C) After the same groove forming treatment as in (A), SnSO ₄ was applied to the groove, and thereafter the same decarburizing annealing and final finish annealing as in (A) were performed. (D) SnSO under the same conditions as (B) without groove formation
₄ was applied linearly. (E) Decarburizing annealing and final finishing annealing were performed without performing the groove forming treatment, and used as comparative materials. Each of the grooves introduced in (A) to (C) above had a width of 150 μm, a depth of 20 μm, and a spacing of 4 mm in the rolling direction, and was linearly introduced in a direction perpendicular to the rolling direction. The width of the SnSO ₄ coating area in (B) and (C) is 100
μm. The sample (A) is a material in which a groove is only introduced into a steel plate. The cross-sectional structure of each of the samples (A) to (E) that passed through these steps was observed. As shown in FIG. 1, the samples (B) and (D) had SnSO It was confirmed that fine crystal grains having an average crystal grain size of 0.5 mm continued from the coated portion of No. _{4 to} the other steel sheet surface in the thickness direction. In sample (C), fine crystal grains continuous from the groove bottom to the other steel sheet surface in the thickness direction were observed. Further, Epstein coupons were collected from these samples, and the magnetic properties after strain relief annealing were measured. Table 1 shows the measurement results. Here B ₈ shows the magnetic flux density at a magnetizing force 800A / m. [Table 1] As shown in Table 1, the samples (B) and (C) formed by combining the linear grooves on the surface of the steel sheet and the linear regions of the fine crystal grains were the samples (A), Fine grain only sample
Iron loss lower than (D) was obtained. From the comparison between Sample (B) and Sample (C), Sample (C) in which fine particles are formed under the linear groove also has an effect of reducing iron loss, but has a groove like Sample (B). It was found that the effect of reducing the iron loss was higher when the fine particles were linearly generated in the other portions. The effect of reducing iron loss in a steel sheet having a combination of linear grooves and fine crystal grains as described above is not yet clear, but is considered as follows. That is, sample (C)
In this method, fine particles were introduced to generate more magnetic poles under the groove having the magnetic pole generating action by itself, and as a result, the effect of reducing iron loss was observed. Then, since a magnetic pole of fine grains was introduced separately from the groove in the region where no magnetic pole was originally formed, (B) is
It is considered that a lower iron loss than (C) was obtained. As described above, the present invention relates to a method for producing fine crystal grains having a linear groove extending in a direction substantially perpendicular to the rolling direction on a surface thereof and penetrating a plate thickness in a portion other than the linear groove in the rolling direction. Thus, the iron loss can be reduced more than before by generating a band-shaped region extending in a direction substantially perpendicular to the above. Next, the results of various experiments performed to examine the proper range of the grooves and the proper range of the formation region of the fine crystal grains in the present invention will be described. First, the preferred range of the linear groove formed on the surface of the steel sheet was examined. 2 and 3 show the relationship between the width and the depth of the linear groove formed in the steel plate having a plate thickness of _{0.23 mm} and the iron loss W _17/50 , respectively. From these figures, the groove width is
0.3 when the groove depth is 10 μm or more and 70 μm or less.
It is understood that a low iron loss of 80 W / kg or less can be stably obtained.
Regarding this groove width, a low iron loss can be obtained even if it exceeds 300 μm, but the magnetic flux density is remarkably reduced. 4 and 5 show the relationship between the groove deviation angle and the iron loss from a direction perpendicular to the rolling direction when the groove width is 200 μm and the groove depth is 20 μm, respectively, the groove interval and the iron loss in the rolling direction. The relationship is shown below. From these figures, in order to obtain a low iron loss of 0.80w / kg or less, the groove interval in the rolling direction should be 1mm or more and 30mm or less.
Hereinafter, it is understood that the deviation angle of the groove may be set within 30 ° from the direction perpendicular to the rolling direction. Next, a region where fine crystal grains are to be formed in a portion other than the groove was examined. In the following experiment,
The width of the linear groove is 200 μm, the depth is 25 μm, the groove interval is 4 mm, and the linear groove is introduced at right angles to the rolling direction. Also, fine crystal grains
It was generated by applying SnSO ₄ before decarburization annealing. FIG. 6 shows the relationship between the width in the rolling direction and the magnetic characteristics of a linear region of fine crystal grains generated between grooves. In this experiment, the interval between the linear grooves was set to 4 mm, and only one fine grain region was introduced between the grooves at a distance of 2 mm from the grooves in a direction perpendicular to the rolling direction. As is clear from FIG. 6, when the width of the fine grain region on the steel sheet surface is 2 mm or less, a lower iron loss value is obtained than when only the grooves are formed. If the width of the fine crystal grain region exceeds 2 mm, the magnetic flux density decreases and the iron loss value increases. FIG. 7 shows the relationship between the distance between the fine-grain regions and the core loss. In this experiment, the width of the fine-grain region was set to 0.5 mm, and the fine-grain region was introduced so as not to exist under the linear groove. According to FIG. 7, the interval between the fine grain regions is 1 mm or more.
It can be said that there is an iron loss reducing effect in the range of 50 mm or less.
Further, as for the angle for introducing the fine grain region, it can be said that the range of 0 ° to 30 ° is suitable from the experimental results shown in FIG. Next, as a result of examining the relationship between the state of formation of the fine crystal grain regions and the iron loss characteristics, the following was found.
That is, in the plan views of the magnetic steel sheets shown in FIGS. 9A to 9D, in order to obtain good iron loss characteristics, as shown in FIG. In the case where the fine crystal grains having a diameter are arranged in a line, any of several rows in the rolling direction within the width of the fine grain region as shown in FIG. 9B may be used. Also, as shown in FIG. 9C, when the fine grain region is introduced at a predetermined deviation angle from a direction perpendicular to the rolling direction,
The band-like fine crystal grain regions may intersect with the linear linear grooves. Further, as shown in FIG. 9D, the effect of reducing iron loss was similarly confirmed when two or more fine grain regions were formed between grooves on the surface of the steel sheet. In addition, the fine crystal grains having the magnetic domain refining effect are greater when they exist over the plate thickness. Note that, in the experiments shown in FIGS.
μm and a depth of 20 μm, and introduced linearly in a direction perpendicular to the rolling direction at an interval of 4 mm in the rolling direction. As described above, in the present invention, by introducing linear grooves on the surface of the steel sheet at a substantially right angle to the rolling direction, magnetic domains are formed by the magnetic poles formed in the grooves to reduce the iron loss and further reduce the iron loss. By introducing a strip-shaped subdivided crystal region extending in a direction substantially perpendicular to the rolling direction into a portion having no groove, the iron loss is further reduced as compared with the case where only the groove is formed. It is considered that the iron loss reduction mechanism is because the magnetic poles are formed by fine grains separately from the groove portions where the magnetic poles are already generated, and the magnetic domains are further subdivided. It is desirable that the band-like region of the fine crystal grains be continuous in a direction substantially perpendicular to the rolling direction. However, even if there is a discontinuous portion as shown in FIG. 9, the effect of reducing iron loss is obtained. It is desirable that the fine crystal grains penetrate the plate thickness in order to generate the magnetic pole, but even if they do not penetrate, the effect of reducing iron loss is obtained. As for the linear grooves, as shown in FIG. 2, when the width of the groove is too small, the effect of reducing iron loss is small, while when the width of the groove is excessively wide, the magnetic flux density is lowered. Therefore, the groove width should be 30 μm or more and 300 μm or less .
If the depth of the groove is less than 10 μm, the effect of magnetic domain refining is insufficient, and if it is deeper than 70 μm, the hysteresis loss increases.
10 µm to 70 µm is appropriate. The deviation angle of the groove from the direction perpendicular to the rolling direction is 0 ° to 30 ° because the hysteresis loss increases as the groove direction approaches the rolling direction.
° range . If the groove interval is smaller than 1 mm, the hysteresis loss tends to increase, and if it is larger than 30 mm, there is no magnetic domain refining effect. Therefore, the appropriate range of groove width is 1mm
30 mm. Next, we describe the preferred range of the fine crystal grain region for introducing the strip. Since the fine crystal grains themselves have a large deviation from the rolling direction of the crystal orientation [001], the expansion of the fine grain region leads to a decrease in magnetic flux density and an increase in iron loss. Therefore, from the results of FIG. 6, the width of the fine grain region is set to 2 mm or less in order to reduce the iron loss as compared with the case of only the groove .
You. Further, if the interval between the fine grain regions is excessively reduced, the ratio of the fine grain portion in the entire steel sheet is increased and the hysteresis loss is increased. On the other hand, the interval is 50mm
If it exceeds, the effect of domain refining cannot be expected. Therefore, the interval between the fine grain regions is 1 mm to 50 mm according to FIG. Further, the deviation angle from the direction orthogonal to the rolling direction of the band-like fine grain region is 0 ° to 30 ° for the same reason as in the case of the groove.
And In the grain-oriented electrical steel sheet of the present invention, a slab for a grain-oriented electrical steel sheet is hot-rolled according to a conventional method, and thereafter, if necessary, hot-rolled sheet annealing is performed. The final product thickness is obtained by cold rolling two or more times, followed by decarburizing annealing and then final finishing annealing, and then a normal top coat is applied to obtain a product. The groove may be introduced either before or after the final finish annealing. Examples of the method of forming the groove include a method of locally performing an etching treatment, a method of scribing with a blade or the like, a method of rolling with a roll having protrusions, and the like. However, the method of rolling the steel sheet after finish annealing with a gear-type roll and then annealing at a high temperature as in the method disclosed in Japanese Patent Publication No. Sho 62-53579 results in both groove formation and generation of fine crystal grains. The fine grains formed in this case are directly below the grooves, and the effect of reducing iron loss is small because the fine grains do not penetrate the plate thickness. The most desirable method for introducing grooves is to form an etching resist on a steel plate after the final cold rolling by printing or the like, and then to form grooves by electrolytic etching. Next, as a method for obtaining fine grains, a metal such as Sn, Sb, B, Bi, S, Pb, As, Se, Te, or an oxide or sulfide thereof is attached to the base iron portion. , Normal decarburization annealing,
There are a method of performing finish annealing, a method of locally applying mechanical strain before finish annealing, and a method of locally irradiating a laser or a plasma flame and performing high-temperature heat treatment. Example 1 As an inhibitor, a hot-rolled 3.2% silicon steel sheet containing MnSe, Sb, and AlN was rolled to a thickness of 0.23 mm by two cold-rollings sandwiching intermediate annealing. (A) and (B)
By performing the above steps, samples (A) and (B) were obtained, respectively. (A) After applying an etching resist by gravure offset printing, a linear groove is formed by electrolytic etching, and the etching resist is removed by dipping in an alkaline solution. (B) After forming grooves by the same process as in (A), a fine grain generation process of applying SnSO ₄ powder at a width of 100 μm and an interval of 4 mm perpendicular to the rolling direction was performed on an intermediate region between adjacent grooves. . (C) As a comparative example, a sample (C) was used without performing both the groove formation processing and the fine grain generation processing. The grooves introduced in (A) and (B) have a width of 170
μm, a depth of 20 μm, and introduced at intervals of 4 mm in a direction perpendicular to the rolling direction. These steel sheets were subjected to decarburization annealing, followed by final annealing, and further overcoated. In the cross section of the product obtained in this way, (A) showed only grooves, whereas (B) showed grains penetrating the plate thickness under the SnO ₂ coating area in addition to the grooves. Fine grains with a diameter of about 0.5 mm were found. Table 2 shows the results obtained by collecting Epstein coupons from the product thus obtained, performing strain relief annealing, and measuring magnetic properties. As is evident from Table 2, the iron loss is lower in the adaptation example in which the linear fine crystal grain region is introduced between the grooves than in the conventional steel sheet in which only the grooves are introduced. [Table 2] EXAMPLE 2 A hot rolled plate of 3.2% silicon steel containing MnSe and AlN as inhibitors was subjected to 0.18 cold rolling twice with intermediate annealing.
It was rolled to a thickness of mm and subjected to the following processes (D) to (F) to obtain samples (D) to (F), respectively. (D) After applying an etching resist by gravure offset printing, a linear groove is formed by electrolytic etching, and the etching resist is removed by dipping in an alkaline solution. (E) After forming a groove by the same process as the sample (D), place a 100 μm
A SnO ₂ powder was applied at an interval of 4 mm. (F) After forming a groove by the same process as sample (D), SnO ₂
Powder was filled into the groove. (G) A comparative example without a groove forming treatment. The grooves introduced in (D) to (F) have a width of 180 μm.
m and a depth of 18 μm, and were introduced at 6 mm intervals from the rolling direction.
Samples (E), (F), and (G) were further subjected to decarburization finish annealing, and then to final finish annealing, followed by a topcoat coating. As a result of observing the cross section of the product thus obtained and observing it, in the sample (E), fine grains having a grain diameter of 0.3 mm penetrating in the Sn coating portion in the region between the grooves were found. On the other hand, in (F), a similar grain region was formed below the groove. Epstein coupons were collected from the product thus obtained, and after the strain relief annealing, the magnetic properties were measured. Table 3 shows the results. [Table 3] As is apparent from Table 3, the conforming example having fine grains penetrating the plate thickness in a portion other than the groove shows a lower iron loss value than the comparative example having the fine grains below the groove. The grain-oriented electrical steel sheet of the present invention has on its surface linear grooves extending in a direction substantially perpendicular to the rolling direction, and a width penetrating the sheet thickness between adjacent grooves. A grain-oriented electrical steel sheet having a low iron loss having a fine crystal grain area of 2 mm or less,
The steel sheet according to the present invention not only exhibits a lower iron loss than the conventional steel sheet, but also has no deterioration of the iron loss due to strain relief annealing.
Can be used with wound iron cores, greatly contributing to transformer efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a cross-sectional structure of a steel plate. FIG. 2 is a diagram showing the relationship between groove width and iron loss W _17/50 . FIG. 3 is a diagram showing a relationship between groove depth and iron loss W _17/50 . FIG. 4 is a diagram showing a relationship between a groove introduction angle and iron loss W _17/50 . FIG. 5 is a diagram showing the relationship between groove spacing and iron loss W _17/50 . FIG. 6 is a view showing the relationship between the width of a fine grain region and iron loss W _17/50 . FIG. 7 is a diagram showing the relationship between the interval between fine grain regions and iron loss W _17/50 . FIG. 8 is a diagram showing a relationship between a fine grain region introduction angle and iron loss W _17/50 . FIG. 9 is a diagram showing an example of a macrostructure when a fine grain region is introduced.

Continuing on the front page (72) Inventor Kazuhiro Suzuki 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Works Co., Ltd. (72) Inventor Michio Komatsubara 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation (56) References JP-A-6-100997 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 1/12-1/375

Claims (1)

(57) [Claim 1] A grain-oriented electrical steel sheet having a plurality of linear grooves extending on a surface thereof in a direction substantially orthogonal to a rolling direction,
The linear groove has a width of 30 μm or more and 300 μm or less and a depth of 10 μm.
m to 70 μm, spacing in the rolling direction is 1 mm to 30 mm
Bottom, deviation angle from the direction perpendicular to the rolling direction is within 30 °
And a band-like region consisting of a group of fine crystal grains is provided between adjacent grooves, and the band-like fine-grain region has a width of 2 mm or less and a pressure
1mm or more and 50mm or less in the rolling direction, perpendicular to the rolling direction
A grain- oriented electrical steel sheet with low iron loss, wherein the angle of deviation from the direction is within 30 ° .