JPH07320921A - Directional electromagnetic steel sheet at low iron loss - Google Patents

Abstract

PURPOSE:To further improve the magnetic characteristics especially the iron loss characteristics by a method wherein a band region comprising fine crystal particle group are provided between adjacent trenches in the almost orthogonal direction to the rolling direction. CONSTITUTION:As an inhibitor, hot rolled sheet comprising silicon steel is rolled by two time cold rolls and after coating with an etching resist, linear trenches are formed by electrolytic etching step. After the trench formation, the free particle producing step coating SnSO4 particles is performed in the orthogonal direction to the tolling direction in the intermediate regions between adjacent trenches.. In such a constitution, the linear trenches are in width between 30mum and 300mum, in depth 10mum to 70mum, the interval in the rolling direction between 1mm-30mm, the deflection angle not exceeding 30 deg., on the other hand, the band fine particle region is in width not exceeding 2mm, the interval in the rolling direction between 1mm-50mm, the deflection angle from the orthogonal direction to the rolling direction not exceeding 30 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low iron loss grain oriented electrical steel sheet suitable for use as an iron core of a transformer or other electric equipment. The grain-oriented electrical steel sheet is mainly used as an iron core material of a transformer and is required to have good magnetic properties. In particular, it is important that the energy loss when used as an iron core, that is, the iron loss is low.

[0002]

2. Description of the Related Art Conventionally, in order to reduce iron loss, the crystal orientation is highly aligned with the (110) [001] orientation, the Si content is increased to thereby increase the electrical resistance of the steel sheet, and the impurities are reduced. Various methods have been performed, such as allowing the plate to be thin and reducing the plate thickness. As a result, iron loss W _17/50 (magnetic flux density 1.7
Iron loss value at T, 50Hz) is 0.9 W / kg or less. However, metallurgical methods cannot be expected to further improve iron loss.

Therefore, in recent years, various methods for artificially subdividing magnetic domains have been tried as means for achieving a significant reduction in iron loss. Among them, the method currently industrialized is to irradiate a laser on the surface of a steel sheet that has been finish-annealed, as disclosed in the method proposed in JP-B-57-2252 for improving the iron loss characteristics of grain-oriented electrical steel sheets. There is a way.
However, although this method is effective in reducing iron loss, it has a drawback that the iron loss is deteriorated by stress relief annealing, and is not used for wound cores that require stress relief annealing.

Japanese Patent Publication No. 62-54873 as an iron loss reduction technique which enables strain relief annealing by improving such a magnetic domain subdivision method.
The low iron loss unidirectional electrical steel sheet manufacturing method disclosed in the publication is a method in which the insulating film is locally removed from the finished annealed steel sheet by a laser or mechanical means, and then the film removal portion is pickled, a knife, etc. A method of forming a linear groove locally by a method such as mechanically scribing directly on the base metal by means of a method of applying a phosphoric acid-based tension-imparting coating treatment so as to fill the groove is also available. -53579 discloses a method for manufacturing low iron loss unidirectional electrical steel sheets, which is based on 90-220 for finish annealed steel sheets.
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 heat-treating at a temperature of 750 ° C. or higher is further described in Japanese Examined Patent Publication No. 3-69968. Proposed and disclosed are methods of introducing linear notches in a direction substantially perpendicular to the rolling direction of the subsequent steel sheet.

[0005]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 62-54873
JP-B, JP-B-62-53579 and JP-B-3-69968
The steel sheets obtained by the method disclosed in the publication are common in 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 improving principles. At present, steel sheets using these methods are industrially produced as magnetic steel sheets capable of stress relief annealing. However, these steel sheets cannot be said to have a sufficient magnetic domain subdivision 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.

Therefore, an object of the present invention is to provide a grain-oriented electrical steel sheet having further improved magnetic characteristics, particularly iron loss characteristics, with respect to the grain-oriented silicon steel sheet having grooves formed on its surface.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the inventors have found that a steel sheet having a linear groove extending on the surface in a direction substantially perpendicular to the rolling direction, Conventionally, there is a magnetic steel sheet in which fine crystal grains with a fine grain size exist continuously or discontinuously in the direction perpendicular to the rolling direction in a portion other than the groove, and the width of the region where the fine crystal grains exist is 2 mm or less. It was obtained as a finding that it shows a lower iron loss than
The invention was made.

That is, the present invention is a grain-oriented electrical steel sheet having a plurality of linear grooves extending on the surface in a direction substantially orthogonal to the rolling direction, wherein a band-shaped region composed of a group of fine crystal grains is formed between adjacent grooves. It is a grain-oriented electrical steel sheet with low iron loss characterized by being provided in a direction substantially orthogonal to the rolling direction.

The linear groove has a width of 30 μm or more and 300 or more.
μm or less, depth of 10 μm or more and 70 μm or less, spacing in the rolling direction of 1 mm or more and 30 mm or less, deviation angle from the direction orthogonal to the rolling direction is 30 ° or less, and the band-shaped fine grain region has a width of 2 mm or less, rolling It is preferable that the interval between the directions is 1 mm or more and 50 mm or less, and the deviation angle from the direction orthogonal to the rolling direction is within 30 °.

The results of the research on which the present invention is based will be described below. Contains MnSe and AlN as inhibitors
Intermediate annealing of Si: 3.3% silicon-containing steel hot-rolled sheet 2
It was cold-rolled once to a thickness of 0.23 mm and then subjected to the following five processes (A) to (E) to obtain various electromagnetic steel sheets.

(A) After applying an etching resist by gravure offset printing, electrolytic etching was performed to form linear grooves, followed by decarburizing annealing and then final finishing annealing. (B) After performing the same groove formation treatment as in (A) and resist removal treatment, 3 g per 1 m ² of SnSO ₄ is linearly formed in the direction parallel to the groove in the middle between the adjacent grooves. After that, the same decarburization annealing and final finishing annealing as in (A) were performed.
There was one SnSO ₄ linear coating part in each groove. (C) After the same groove formation treatment as in (A), SnSO ₄ was applied to the groove portions, and thereafter, the same decarburization annealing and final finishing annealing treatment as in (A) were performed. (D) SnSO under the same conditions as (B) without groove formation treatment.
₄ was applied linearly. (E) Decarburization annealing and final finishing annealing were performed without using the groove forming treatment to obtain a comparative material.

The grooves introduced in the above (A) to (D) had a width of 150 μm, a depth of 20 μm and an interval of 4 mm in the rolling direction, and were introduced linearly in the direction orthogonal 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 introduced into a steel plate.

The cross-sectional structure of each of the samples (A) to (E) which have undergone these steps was observed. As a result, the cross-sectional structure is schematically shown in FIG. It was confirmed that fine crystal grains with an average crystal grain size of 0.5 mm were formed continuously from the coated part of _{4 to} the surface of the other steel plate in the plate thickness direction. In addition, in the sample (C), continuous fine crystal grains were observed from the groove bottom surface to the other steel plate surface in the plate thickness direction. Further, Epstein test pieces were sampled from these samples, and the magnetic characteristics after stress relief annealing were measured. The measurement results are shown in Table 1. Here, B ₈ represents the magnetic flux density at a magnetizing force of 800 A / m.

[0014]

[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 fine crystal grains are the samples (A) having only the grooves, Samples with only fine particles
A lower iron loss than that of (D) was obtained. From the comparison between this sample (B) and sample (C), the sample (C) in which fine particles are generated in the lower part of the linear groove has the iron loss reducing effect, but It was found that the effect of reducing the iron loss was higher when the fine particles were linearly generated in the other portions.

[0016]

The iron loss reducing action in the steel sheet in which the linear grooves and the fine crystal grains are combined as described above is not clear yet, but it is considered as follows. That is, sample (C)
In this case, fine particles are introduced under the groove that has a magnetic pole generating effect even by itself, and as a result, the effect of iron loss reduction was observed. Then, since magnetic poles made of fine particles were introduced into the area where magnetic poles were not originally generated in addition to the grooves, (B)
It is considered that the iron loss was lower than that of (C).

As described above, according to the present invention, a linear groove extending in a direction substantially perpendicular to the rolling direction is formed on the surface, and fine crystal grains penetrating the plate thickness in the portion other than the linear groove are rolled in the rolling direction. The iron loss was successfully reduced more than in the past by forming a band-shaped region extending in a direction substantially perpendicular to the above.

Next, the results of various experiments conducted to investigate the proper range of the groove and the proper range of the fine crystal grain forming region in the present invention will be described. First, the suitable range of the linear grooves formed on the surface of the steel sheet was examined. 2 and 3 show the relationship between the width and depth of the linear groove formed in a steel plate having a plate thickness of _{0.23 mm} and the iron loss W _17/50 . From these figures, the groove width is
0 when the groove depth is 30 μm or more and the groove depth is 10 μm or more and 70 μm or less.
It can be seen that a low iron loss of 80 W / kg or less can be stably obtained.
A low iron loss can be obtained when the groove width exceeds 300 μm, but the magnetic flux density remarkably decreases, so the proper range of the groove width is 30 μm or more and 300 μm or less.

4 and 5 show the relationship between the groove deviation angle from the direction orthogonal to the rolling direction and the iron loss when the groove width is 200 μm and the groove depth is 20 μm, respectively, and the groove interval and the iron loss in the rolling direction are shown. Shows the relationship with. From these figures, in order to obtain a low iron loss of 0.80 w / kg or less, the groove spacing in the rolling direction is 1 mm or more and 30 mm.
It will be seen below that the deviation angle of the groove is preferably within 30 ° from the direction perpendicular to the rolling direction.

Next, the fine crystal grain forming region to be formed in the portion other than the groove portion was examined. In the following experiment,
The width of the linear grooves is 200 μm, the depth is 25 μm, the groove interval is 4 mm, and the linear grooves are 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 for the linear region of fine crystal grains generated between the grooves. In this experiment, the distance between the linear grooves was 4 mm, and only one fine grain region was introduced between the grooves at a position 2 mm away from the grooves in a direction orthogonal to the rolling direction. As is clear from FIG. 6, when the width of the fine grain region on the surface of the steel sheet is 2 mm or less, the iron loss value lower than that when only the groove is formed is obtained. If the width of the fine crystal grain region exceeds 2 mm, the magnetic flux density decreases and the iron loss value increases.

Next, the optimum condition of the interval for introducing the fine crystal grain region is examined, and the result is shown in FIG. 7 by the relationship between the interval of the fine grain region and the iron loss. The width of the fine grain region in this experiment was 0.5 mm, and it was introduced so that the fine grain region did not exist below the linear groove. From Fig. 7, the interval of fine grain area is 1mm or more.
It can be said that there is an iron loss reduction effect in the range of 50 mm or less.
Furthermore, it can be said from the experimental results shown in FIG. 8 that the range of 0 ° to 30 ° is suitable for the angle of introducing the fine grain region.

Next, as a result of investigating the relationship between the state of formation of the fine crystal grain region and the iron loss characteristics, the following was found.
That is, in order to obtain good iron loss characteristics in the plan view of the electromagnetic steel sheets shown in FIGS. In the case where the fine crystal grains having the diameter are arranged in a line, as shown in FIG. 9 (b), there may be a case where several lines are arranged in the rolling direction within the width of the fine grain region. In addition, as shown in FIG. 9 (c), when the fine grain region is introduced at a predetermined deviation angle from the direction orthogonal to the rolling direction,
The band-shaped fine crystal grain region may intersect with the linear groove. Further, as shown in FIG. 9 (d), the iron loss reducing effect was similarly confirmed when two or more fine grain regions were formed between the grooves on the surface of the steel sheet. Further, the fine crystal grains have a greater magnetic domain subdivision effect when they exist over the plate thickness. In addition, in the experiment shown in FIGS.
It was introduced in a linear shape in a direction perpendicular to the rolling direction with a gap of 4 mm in the rolling direction and a depth of 20 μm.

As described above, in the present invention, by introducing a linear groove on the surface of the steel sheet at a substantially right angle to the rolling direction, the magnetic domain is subdivided by the magnetic poles generated in the groove to reduce the iron loss. By introducing a band-shaped subdivided crystal region extending in a direction substantially perpendicular to the rolling direction into the grooveless portion, the core loss is further reduced as compared with the case where only the groove is formed. It is considered that the iron loss reducing mechanism is because a magnetic pole is formed by fine particles and the magnetic domain is further subdivided, in addition to the groove portion where the magnetic pole is already generated.

It is desirable that the strip region of the fine crystal grains is continuous in a direction substantially perpendicular to the rolling direction. However, even if there is a discontinuous portion as shown in FIG. 9, there is an iron loss reducing effect, and It is desirable that the fine crystal grains penetrate the plate thickness in order to generate the magnetic pole, but even if the fine crystal grains do not penetrate, the iron loss reducing effect is obtained.

Regarding the linear groove, as shown in FIG. 2, when the width of the groove is too narrow, the iron loss reducing effect is small, and when the groove width is excessively wide, the magnetic flux density is lowered. Therefore, it is desirable that the groove width is 30 μm or more and 300 μm or less. If the groove depth is shallower than 10 μm, the effect of domain refinement is insufficient, and if it is deeper than 70 μm, the hysteresis loss increases, so 10 μm to 70 μm is appropriate. The deviation angle of the groove from the direction orthogonal to the rolling direction is preferably in the range of 0 ° to 30 ° because the hysteresis loss increases as the direction of the groove approaches the rolling direction. If the groove spacing is narrower than 1 mm, the hysteresis loss tends to increase, and if it is wider than 30 mm, there is no magnetic domain subdivision effect. Therefore, the proper range of groove width is 1 mm to 30 mm.

Next, the preferable range of the fine crystal grain region to be introduced in a band will be described. This fine crystal grain itself has a crystal orientation [00
Since the deviation of 1] from the rolling direction is large, the expansion of the fine grain region leads to a decrease in magnetic flux density and an increase in iron loss. Therefore, from the result of FIG. 6, in order to reduce the iron loss as compared with the case of only the groove, the width of the fine grain region is preferably 2 mm or less. Further, if the spacing between the fine grain regions is reduced too much, the proportion of the fine grain portions in the entire steel sheet is increased and the hysteresis loss is increased. On the other hand, the spacing is 50 mm
If it exceeds, the magnetic domain subdivision effect cannot be expected. Therefore, the interval between the fine grain regions is preferably 1 mm to 50 mm as shown in FIG.
Further, the deviation angle from the direction orthogonal to the rolling direction of the band-shaped fine grain region is 0 ° for the same reason as in the case of the groove.
30 ° is desirable.

In the grain-oriented electrical steel sheet of the present invention, a slab for grain-oriented electrical steel sheet is hot-rolled according to a conventional method, and after that, hot-rolled sheet annealing is carried out if necessary, and then one or intermediate annealing is sandwiched. The final product sheet thickness is obtained by cold rolling two or more times, then decarburization annealing is performed, and then final finishing annealing is performed, and then a general 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, and a method of rolling with a roll having protrusions. However, as in the method disclosed in Japanese Patent Publication No. 62-53579, a method of rolling a steel sheet after finish annealing with a gear type roll and then annealing at a high temperature brings about both groove formation and generation of fine crystal grains. The fine particles formed in this case are directly below the groove, and since the fine particles do not penetrate the plate thickness, the iron loss reducing effect is small. The most desirable method of introducing the groove is a method in which after the final cold rolling, an etching resist is attached to the steel sheet by printing or the like, and then the groove is formed by electrolytic etching treatment.

Next, as a method for obtaining fine grains, after depositing a metal such as Sn, Sb, B, Bi, S, Pb, As, Se, or Te or its oxide, sulfide, etc. on 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, a method of locally irradiating a laser or plasma flame, and a high temperature heat treatment.

[0030]

【Example】

Example 1 A hot-rolled 3.2% silicon steel sheet containing MnSe, Sb, and AlN as an inhibitor was rolled to 0.23 mm thickness by two cold rolling processes with intermediate annealing, and described below (A), and (B)
The above steps were performed to obtain a sample (A) and a sample (B), 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 immersion in an alkaline solution. (B) After forming grooves by the same process as in (A), a fine particle generation process was performed in which SnSO ₄ powder was applied in the intermediate region between adjacent grooves at a width of 100 μm at a right angle to the rolling direction and an interval of 4 mm. . (C) As a comparative example, a sample (C) was prepared without performing the groove forming process and the fine grain forming process.

The groove introduced in the above (A) and (B) has a width of 170 mm.
It was introduced at a distance of 4 mm in a direction perpendicular to the rolling direction at a depth of 20 μm and a thickness of 20 μm. These steel sheets were decarburized annealed, then final annealed, and then topcoated. The cross section of the product obtained in this way shows only grooves in (A), but in (B), in addition to the grooves, the grains that penetrate the plate thickness below the SnO ₂ application area Fine particles with a diameter of about 0.5 mm were seen. Table 2 shows the results of measuring the magnetic properties of the Epstein test pieces obtained from the thus obtained product after stress relief annealing. As is clear from Table 2, the iron loss is lower in the conforming example in which the linear fine crystal grain regions are introduced between the grooves than in the conventional steel sheet in which only the grooves are introduced.

[0032]

[Table 2]

Example 2 A hot rolled sheet of 3.2% silicon steel containing MnSe and AlN as inhibitors was 0.18 by two cold rolling processes with intermediate annealing.
After rolling to a thickness of mm, the following treatments (D) to (F) were performed to obtain samples (D) to (F), respectively. (D) After applying the etching resist by gravure offset printing, a linear groove is formed by electrolytic etching, and the etching resist is removed by immersion in an alkaline solution. (E) After grooves were formed by the same treatment as in sample (D), a width of 100 μm was formed in the groove-free area in the middle of the grooves perpendicular to the rolling direction.
, SnO ₂ powder was applied at intervals of 4 mm. (F) After forming a groove by the same treatment as for sample (D), SnO ₂
Powder was filled in this groove. (G) A comparative example was obtained without performing the groove forming treatment.

The groove introduced in (D) to (F) has a width of 180 μm.
It was introduced at a distance of 6 mm from the rolling direction.
Samples (E), (F) and (G) were further decarburized finish annealed, then final finish annealed and then overcoated. As a result of observing the cross section of the product thus obtained and observing it, in the sample (E), fine particles penetrating a plate thickness of 0.3 mm were generated in the Sn coated portion in the region between the grooves. On the other hand, in (F), similar grain regions were formed in the lower part of the groove. Epstein test pieces were sampled from the products thus obtained, and after annealing for strain relief, magnetic properties were measured. The results are shown in Table 3.

[0035]

[Table 3]

As is clear from Table 3, the conforming example having fine grains penetrating the plate thickness in the portion other than the groove shows a lower iron loss value than the comparative example having fine grains in the lower part of the groove.

[0037]

The grain-oriented electrical steel sheet of the present invention has linear grooves extending on the surface in a direction substantially perpendicular to the rolling direction, and has a width of 2 mm or less which penetrates the sheet thickness between adjacent grooves. A grain-oriented electrical steel sheet having a low iron loss having a fine crystal grain region,
The steel sheet according to the present invention not only exhibits a low iron loss superior to conventional ones, but also has no deterioration in iron loss due to strain relief annealing, so that the laminated core,
It can be used with both wound iron cores and greatly contributes to the improvement of transformer efficiency.

[Brief description of 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 the 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 diagram showing the relationship between the width of the 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.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keiji Sato, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Technical Research Division, Kawasaki Steel Co., Ltd. (72) Kazuhiro Suzuki, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba (72) Inventor Michio Komatsubara, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Kawasaki Steel Co., Ltd.

Claims (2)

[Claims] 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,
A grain-oriented electrical steel sheet with low iron loss, characterized in that a band-shaped region composed of a group of fine crystal grains is provided between adjacent grooves in a direction substantially orthogonal to the rolling direction. 2. The linear groove has a width of 30 μm or more and 300 μm or less, a depth of 10 μm or more and 70 μm or less, and an interval of 1 in the rolling direction.
mm or more and 30 mm or less, the deviation angle from the direction orthogonal to the rolling direction is 30 ° or less, and the band-shaped fine grain region has a width of 2 mm or less, a spacing in the rolling direction of 1 mm or more and 50 mm or less, from a direction orthogonal to the rolling direction. 2. The grain-oriented electrical steel sheet with low iron loss according to claim 1, wherein the deviation angle is less than 30 °.