JP2000045052A - Low core loss and grain-oriented silicon steel sheet excellent in shape in edge part in width direction of coil and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a defect in shape in the edge parts in the width of a coil by high temp.-long time annealing including secondary recrystallization by previously subjecting both edge parts in the width direction of a grain-oriented silicon steel sheet coil contg. specified amounts of Si and Mn to secondary recrystallization promoting treatment and suppressing the formation of fine crystals. SOLUTION: A grain-oriented silicon steel sheet contg., by weight, 1.5 to 7.5% Si and 0.03 to 2.5% Mn is formed into a coiled shape and is subjected to a high temp.-long time annealing including secondary recrystallization to obtain the low core loss and grain-oriented silicon steel sheet. Before this high temp.-long time annealing, at least either the edge part in the width direction of the coil is subjected to additional secondary recrystallization promoting treatment. This treatment can be executed by controlling the coiling tension to >=3 kgf/mm2 and subjecting the primarily recrystallized <=2 mm in the region of >=30 mm from the coil edge part to grain refining or grain growth driving force strengthening. In this way, the distance at which the area ratio of the crystal grains of <=2 mm grain size is made 15% is controlled to <=30 mm from the coil edge part, by which the steel sheet excellent in the shapes in the edge parts in the width direction of the coil can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain-oriented electrical steel sheet used for an iron core of a transformer or a generator, and more particularly to a method for producing a grain-oriented silicon steel sheet having an excellent shape at an end portion in a coil width direction. It is intended to be proposed together with.

[0002]

2. Description of the Related Art Si has a crystal orientation of (11).
Grain-oriented electrical steel sheets oriented in the 0) [001] or (100) [001] orientation are widely used as various core materials in the commercial frequency range because of their excellent soft magnetic properties. In this application, the properties required for _grain- oriented electrical steel sheets are, in general, the iron loss represented by W _17/50 (W / kg), which is the loss when magnetized to 1.7 T at a frequency of 50 Hz. Low is important, and generally 800 A / m
It is important that the magnetic flux density represented by the magnetic flux density B ₈ (T) at the magnetizing force is high.

[0003] Such a grain-oriented electrical steel sheet contains AlN,
Precipitates called inhibitors such as MnSe and MnS are finely dispersed to suppress the growth of primary recrystallized grains (the ability is called inhibitory force), and is called Goss orientation by the secondary recrystallization phenomenon ( 110) It is manufactured by selectively growing only crystal grains close to the [001] orientation. After secondary recrystallization, the inhibitor is decomposed to remove it from the steel sheet.
Although high-temperature heating at around 00 ° C. (generally called purification annealing) is performed, secondary recrystallization and purification annealing are usually performed continuously, and are collectively called final finish annealing. Therefore, this final finish annealing is a high temperature and long time annealing, but since the steel sheet is annealed in a coiled state, the surface of the steel sheet is made of a non-metallic material to prevent fusion between the laminated steel sheets. After applying the annealing separator, it is subjected to final finishing annealing.

However, as a problem of high-temperature and long-time annealing, there is a defect in the shape of the end portion in the coil width direction. In other words, since the surface of the steel sheet is coated with a non-metallic material having low thermal conductivity and wound in a coil shape, when heated from outside the coil,
The heat conduction proceeds from the end in the coil width direction, and the heat conduction in the coil radial direction is suppressed by the heat insulating effect of the annealing separator between the steel sheet layers. Therefore, when the temperature of the coil rises, a large temperature difference occurs between the end and the center in the coil width direction,
Since relatively large thermal expansion occurs at the coil end, the end is deformed, resulting in a defective shape of the coil width end of the steel sheet after final finish annealing. Such a shape defect at the end in the coil width direction not only hinders subsequent processes such as removal of the unreacted annealing separating agent and a coating application / baking process, but also causes poor magnetic characteristics and a voltage change. The size of the slit treatment for forming the core of the transformer is changed to cause a material defect, and the thickness of the transformer core is varied to cause an industrial trouble.

As a conventional method for solving the problem of the defective shape of the end portion in the coil width direction, Japanese Patent Publication No. 52-13169 discloses a technique of winding the coil end so that the side edge becomes uneven. A method of changing the winding tension in the direction is disclosed in Japanese Patent Publication No. 59-14522. Of the conventional methods, the technique disclosed in Japanese Patent Publication No. 52-13169 applies a concentrated load to the side edges of the projections.
There is a possibility that buckling of the protruding portion may be caused, and conversely, shape deterioration may be promoted. Further, the technique disclosed in Japanese Patent Publication No. 59-14522 discloses that the arbitrary width of the end side edge of the coil is preferentially and selectively cooled over the center portion at the time of annealing immediately before final finish annealing, and the end portion and the center portion are cooled. Due to the temperature difference between the coil and the end, relative plastic deformation is generated at the end, so that when wound into a coil, relatively strong tension is applied to the coil end side edge compared to the coil center, thereby The purpose is to reduce the distortion generated at the end side edge. However, in this method, the distortion of the coil end side edge existing before the final finishing is further promoted, and conversely, the coil end shape is deteriorated, and it is difficult to obtain a desired effect. is there.

[0006]

As described above, high temperatures,
Defects in the end of the coil width direction that occur after the final annealing, which is a long-time treatment, can be caused by making a cut in the end, a method of forming the end into an uneven shape, and applying a relatively strong tension to the end of the coil. The conventional method such as the adding method cannot solve the problem. Therefore, the present invention has pursued such a difficult problem to the cause of the occurrence of the end shape defect, and has newly found that the temperature at which secondary recrystallization occurs has a great effect on the coil end shape. Effectively solved the problem by applying secondary recrystallization control technology to the coil end.
An object of the present invention is to propose a low iron loss grain-oriented electrical steel sheet excellent in the shape of a coil width end portion and a method for manufacturing the same.

[0007]

Means for Solving the Problems The inventors of the present invention retrospectively studied the cause of the shape failure of the end portion in the coil width direction due to the final finish annealing, and found that the end portion of the coil and the center portion during the high-temperature long-time annealing. Temperature difference, and the thermal expansion difference causes a deformation force to the coil end to the coil center,
At the lower end of the coil, which is in contact with the pace plate of the annealing furnace, the coil weight is applied and a deforming force is also applied.At this time, the structure composed of primary recrystallized grains is compared with the structure composed of secondary recrystallized grains. The amount of deformation due to creep deformation is large for the same deformation force, and it has been newly found that this structural state is the true cause of the shape failure at the end in the coil width direction.

That is, what governs high-temperature deformation that causes defective shape of the end portion in the coil width direction during high-temperature long-time annealing is as follows:
It was found by experiments that it was a high temperature creep deformation.
In the case of the secondary recrystallized structure, the creep strength is greatly increased because the grain boundary density is greatly reduced. Therefore,
As a solution to the above-mentioned problem, it is effective to preferentially secondary recrystallize the coil end portion which receives the deforming force before the coil becomes high temperature. A new recrystallized structure with a reduced proportion of crystal grains of 2 mm or less can provide a large resistance to creep deformation, thereby suppressing substantial deformation. I found out.

Further, in the secondary recrystallized structure after the final finish annealing, even after flattening annealing for correcting the coil set in the next step, excellent results can be obtained in terms of shape and space factor. That is what I discovered. In addition to the above findings, the inventors have found that by devising a method of expressing secondary recrystallization at a low temperature, it is possible to effectively utilize the effect of the secondary recrystallization, solve the above-described problems, and complete the present invention. Was.

That is, the low iron loss grain-oriented electrical steel sheet of the present invention having an excellent shape of the end portion in the coil width direction has a Si content of 1.5 to 7.0 wt.
%, Mn: In a grain-oriented electrical steel sheet containing 0.03 to 2.5 wt%, a certain distance in the width direction is selected from the end in the coil width direction. The constant distance L at which the area ratio in the region becomes 15% is 30 mm or less from both ends or one end, Si: 1.5 to 7.0 wt%, Mn: 0.03 to 2.5 wt% %
In the grain-oriented electrical steel sheet containing, the average value of the in-plane misorientation angle α of crystal grains having a grain size exceeding 2 mm in a region up to a distance of 30 mm from both ends or one end in the coil width direction.
e is 2 mm in the center area of 100 mm width in the coil width direction.
It is characterized by being 3 to 20 degrees larger than the in-plane misorientation angle αc of crystal grains having a diameter of more than 1 mm, and further, Si: 1.5 to 7.0 wt%, M
n: In a grain-oriented electrical steel sheet containing 0.03 to 2.5 wt%, 30 mm from both ends or one end in the coil width direction
The average grain size of crystal grains whose grain size exceeds 2 mm in the region up to the distance of 4 mm or more and the crystal grain size of which exceeds 2 mm in the region of 100 mm width in the center in the coil width direction is 3 than particle size
It is characterized by being smaller than mm or larger than 3 mm.

[0011] The method for producing a low iron loss grain-oriented electrical steel sheet having an excellent shape of the end portion in the coil width direction according to the present invention is as follows: Si: 1.5 to 7.0;
wt%, Mn: 0.03 to 2.5 wt% In order to perform high-temperature long-time annealing including secondary recrystallization by forming a coil of a grain-oriented electrical steel sheet containing 0.03 to 2.5 wt%, both ends in the width direction of the coil before the high-temperature long-time annealing. The region or one end region is subjected to an additional secondary recrystallization acceleration treatment as compared with the center region in the width direction to reduce the frequency of generation of crystal grains having a grain size of 2 mm or less in the end region. It is characterized by the following.

In the manufacturing method of the present invention, the secondary recrystallization accelerating process is a process for refining primary recrystallized grains or a process for enhancing the driving force for grain growth of primary recrystallized grains. The take-up tension should be 3 kgf / mm ² or more, and the area to be subjected to the secondary recrystallization acceleration treatment should be an area of at least 30 mm in the coil width direction from both ends or one end of the coil, or a combination thereof. Are more advantageously fitted.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the details of the present invention will be described below based on investigations and experimental examples. (Experiment 1: Investigation experiment of coil temperature distribution) Width 1000mm, length
4 km, weight of about 10 t
An annealing separator containing MgO as a main component was applied, and thermocouples were installed at the upper end, the center, and the lower end in the width direction at the center in the longitudinal direction of the coil, and the coil was wound into a coil. Thereafter, this coil was subjected to final finish annealing shown in Examples of Japanese Patent Publication No. 62-56206, that is, the temperature was raised to 1200 ° C. at a temperature rising rate of 20 ° C./h, and maintained at this temperature for 10 hours. Cooled down. FIG. 1 shows the change with time of the temperature difference ΔTL between the coil center and the coil upper end at this time. As shown in FIG. 1, it was found that a maximum temperature difference of 240 ° C. occurred between the central portion in the coil width direction and the upper end portion of the coil during the temperature increase.

Incidentally, the degree of the shape defect in the end area in the coil width direction of the coil is determined by the product HD of the wave height: H (mm) and the distance from the width end of the shape defect: D (mm) shown in FIG. The average value in the longitudinal direction of the coil,
The length was 250 mm ² , and the lower end of the coil was 380 mm ² .

Conventionally, when the coil is softened at a high temperature at the time of the final finish annealing, buckling deformation occurs at the coil end in contact with the base plate receiving the coil due to the coil load. And it was
However, as can be seen in this experiment, although the shape defect at the lower end of the coil that is in contact with the base plate is large, the shape defect also occurs at the upper end of the coil, and the coil load and the softening of the coil at high temperatures. Alone cannot explain this result. Also, even if coils having the same size and weight are annealed with the same annealing pattern, coils with different end shapes may be generated, but this cannot be explained only by the theory of coil load and high temperature softening of the coil. It is.

Therefore, the inventors of the present invention believe that although there may be a coil load as a cause for promoting the shape failure, this corresponds only to the lower end portion of the coil subjected to high-temperature and long-time annealing. At the upper end where the coil load is not applied, a temperature difference from the center occurs when the temperature is increased or the temperature is maintained at a high temperature, and it is considered that a stress accompanying deformation is applied to the upper end of the coil due to the difference in the amount of thermal expansion. Therefore, in any case, a large deformation stress is applied to the coil end region at the time of the final finish annealing at a high temperature for a long time, and the true reason that the degree of the shape defect at the end in the coil width direction differs for each coil is as follows. Then, the following experiment was carried out on the assumption that it might be caused by the material itself subjected to the heat treatment.

(Experiment 2: High temperature load tensile test of 3% Si electrical steel sheet) 3.3 wt% of Si and 0.06 wt% of Mn and 0.02 wt% of Se and 0.02 wt% of Al and 0.02 wt% of Sb as inhibitor components
A 0.22 mm-thick decarburized annealed sheet (symbol A) containing this and a steel sheet (final annealed sheet: symbol B) which was finally and annealed to this sheet were used as samples. The average particle size of the decarburized annealed plate A is 8.2 μ
m, and the final finish-annealed sheet B was completely secondary recrystallized, and the average crystal grain size of its macrostructure was 18.4 mm. Using these samples, a high temperature load tensile test (effective length: 100 mm) was performed under a load (σ = 0.75 kgf / mm ² ) at 800 to 1100 ° C. One example (1000 ° C.) of the result is shown in FIG. 3, and FIG. 4 collectively shows the high-temperature deformation rate.

From the results shown in FIG. 3 and the structure observation using an optical microscope, it was found that these deformations under a high-temperature load were caused by high-temperature creep due to slip of crystal grain boundaries. Therefore, as the decarburized annealed sheet has a smaller crystal grain size, the deformation speed increases. Further, it can be seen from FIG. 4 that at 950 ° C. or higher, the deformation rate of the decarburized annealed sheet is higher than the deformation rate of the final finish annealed sheet, and the difference increases as the temperature increases.

From this experiment, it can be seen that there is a large difference in deformation at high temperature between before and after secondary recrystallization, where there is a large difference in crystal grain size, and the occurrence of secondary recrystallization is high. It can be estimated that the degree of deformation becomes more severe as it becomes more and more. Nevertheless, even if the coil has the same secondary recrystallization behavior, sometimes a coil having the same end shape in the coil width direction may be obtained. It was presumed that factors other than the cause, such as coil winding tension, were also somewhat relevant. To verify these estimates, the following experiment was performed using magnesium sulfate as a secondary recrystallization accelerator.

(Experiment 3: Experiment of promoting secondary recrystallization in coil width direction end region and changing coil winding tension) 3.05 wt% S
i, 0.07wt% Mn, 0.02wt% Se, 0.02wt% Al, 0.02w
It contains t% of Sb, 0.012 wt% of Mo, and 0.008 wt% of N, with the balance being iron and unavoidable impurities, 1200 mm wide and 0.1 mm thick.
22 mm, weight 15t prepared 4 coils oriented electrical steel sheet after decarburization annealing, annealing separator of 10 g / m of the surface thereof 5 wt% of TiO ₂ and consisting of the added MgO to 2 wt% of strontium hydroxide
^{2 were} applied. At this time, one coil was coated with an annealing separator and then wound with a winding tension of 2 kgf / mm ² to obtain a coil before final annealing (condition a). The other coil has a winding tension of 8 kgf / mm ² after applying an annealing separator.
To form a coil before final annealing (condition b). In addition, after applying the annealing separator to the other coil, copper sulfide is placed on the annealing separator in the coil end regions between the ends in the coil width direction and a distance of up to 100 mm from the ends. Further, 2 g / m ^{2 was} applied in layers and wound at a winding tension of 2 kgf / mm ² to obtain a coil before the final finish annealing (condition c). For the remaining coil, after applying the annealing separator, copper sulfide is further superimposed on the annealing separator in the coil end area between the ends in the coil width direction and a distance of 100 mm from the end. 2 g / m ²
The coil was applied and wound at a winding tension of 8 kgf / mm ² to form a coil before final annealing (condition d).

The final annealing was carried out in a rotary hearth furnace with each coil placed on a base plate, covered with an inner cover, and charged in a box with a heater. Conditions of final finish annealing, the temperature was raised at a heating rate of average 30 ° C. / h in N ₂ to 850 ° C., in also N _2, was held for 15 hours at 850 ° C., NH ₃ 25% 75% The temperature was raised to 1180 ° C. at an average rate of 15 ° C./h in an atmosphere of H ₂ , kept at 1180 ° C. for 5 hours in H ₂ , and then cooled. Thereafter, the unreacted annealing separating agent was removed, and the average shape defect factor HD in the end portion in the width direction of the coil was measured every 1 m in the coil longitudinal direction, and the average value in each magnetic coil longitudinal length was determined.

The results are shown in Table 1 and the magnetic properties of each coil are shown in Table 2 as the magnetic properties after finish annealing. The same steel plate after decarburization annealing as in this experiment was
Mg with the addition of ₂ % TiO ₂ and 2% by weight strontium hydroxide
Prepare a sample coated with 10 g / m ^{2 of} an annealing separator composed of O and a sample further coated with 2 g / m ^{2 of} copper sulfide on top of this.
Annealing in a laboratory experimental furnace and determining the secondary recrystallization temperature, the secondary recrystallization temperature of the former sample was 1020 ° C,
The secondary recrystallization temperature of the latter sample with additional application of copper sulfide was 95
It had dropped to 0 ° C.

[0023]

[Table 1]

[0024]

[Table 2]

From the results shown in Table 1, it is found that the coils under the conditions c and d in which magnesium sulfate as the secondary recrystallization accelerator is applied to the end portions in the coil width direction have extremely excellent end shapes in the width direction. In particular, under the condition d in which the winding tension was increased to 8 kgf / mm ² , an unprecedented excellent product was obtained, and it was found that a great improvement effect was obtained. When investigating such an effect of coil winding tension, if the tension is weak, the steel sheet is likely to shift between the steel sheet layers during annealing, and at this time, excessive stress is likely to be applied to a part of the steel sheet Therefore, it was found that large deformation tends to occur locally.

Therefore, in order to improve the shape of the end region in the coil width direction, it is necessary to promote secondary recrystallization in this region and to develop secondary recrystallized grains resistant to high-temperature deformation from a low temperature. In particular, it is effective to combine this technique with the technique of increasing the coil winding tension to uniformly apply stress to each steel sheet during high-temperature annealing. As shown in Table 2, there is no difference in the magnetic characteristics under the four conditions.

Next, with respect to the four types of coils obtained in this experiment, a tension coating containing magnesium phosphate and colloidal silica as main components was applied to the surface of the steel sheet and flattened and annealed. At this time, each coil is divided into two, one a minimum tensile tension 0.4 kgf / mm ² to the extent that the coil set is corrected, the coil end area to the shape of the end portion in the width direction area of each coil is corrected depending on the degree of shape defects 0.4 ~8 kgf / mm ²
The other coil was annealed at 800 ° C. while applying a uniform tension of 8 kgf / mm ² while applying a tension of 800 kg. Table 2 shows the magnetic properties of the former coils as the magnetic properties after flattening annealing. In addition, the length of each coil in the rolling direction is 300 mm from both ends in the coil width direction.
A large number of steel sheets of m were cut out, 100 of them were laminated, and the space factor was measured. After performing strain relief annealing at 800 ° C. for 3 hours, the space factor was measured again. These results are also shown in Table 2.

As shown in Table 2, in the coils a and b where the shape of the end portion in the coil width direction is poor, the magnetic properties after the flattening annealing are significantly deteriorated, Under the conditions c and d, the deterioration of the magnetic characteristics is hardly recognized. This is because the coils under the conditions a and b excessively stretched and deformed the steel sheet in order to correct the shape of the end area in the coil width direction, so that many dislocations were introduced into the steel sheet and the magnetic properties were deteriorated.

Also, in the latter case where the straightening treatment by the flattening annealing is performed under the same conditions, the steel sheet collected from the end area in the coil width direction is not subjected to the strain relief annealing (the flattening annealing) under the conditions a and b. After ()), the space factor has already decreased, and after the strain relief annealing, the space factor has significantly deteriorated. When investigating the cause, under the conditions a and b, the steel plate sampled from the end region in the coil width direction has many secondary recrystallization regions having a grain size of 2 mm or less, and this causes such a phenomenon. I understand. Table 3 shows the results of microstructural observation of the steel sheet by macro-etching in the center and end regions in the coil width direction, based on the ratio of secondary recrystallized grains having a grain size of 2 mm or less and the average crystal grain size of secondary recrystallized grains. Show.

[0030]

[Table 3]

From Table 3, it was found that a large number of fine grains having a grain size of 2 mm or less existed in the secondary recrystallized structure in the steel sheet in the end region. A secondary recrystallized structure having fine grains is likely to be generated in an end region in the coil width direction which receives a strong stress due to a difference in thermal expansion before the secondary recrystallization during the final annealing. According to the study of the inventors, it has been found that these fine grains are responsible for a decrease in the space factor.

FIG. 5 shows the area ratio of crystal grains having a grain size of 2 mm or less in the macrostructures of the steel plates a and c after the flattening annealing in relation to the distance from the end in the coil width direction. Here, a crystal grain of 2 mm or less means a crystal grain having an equivalent diameter of an equivalent circle of 2 mm or less, a grain having a poor secondary recrystallization or a fine secondary recrystallization of 2 mm or less. including. In FIG. 5, in the steel sheet “a” in which the shape defect of the coil end region and the space factor were poor, the area ratio of crystal grains of 2 mm or less is high, and the point where the area ratio becomes 15% in the coil width direction The distance L15 from the end is 58 mm and 63 mm. On the other hand, in the steel sheet c excellent in the shape and the space factor of the coil end area, the generation of fine grains is suppressed, and the value of L15 is 25mm
And found to be 21mm.

Considering the reason for obtaining such a result, if the structure containing fine grains of 2 mm or less is mixed with the coarse secondary recrystallized grain structure, the steel sheet will not be subjected to flattening annealing. Since a non-uniform internal strain is contained at the time of straightening, the shape of the steel sheet after the strain relief annealing is deteriorated again, and eventually, the space factor is reduced. On the other hand, under the conditions c and d in which the secondary recrystallization accelerator is applied, since the secondary recrystallization exceeding 2 mm proceeds to the end portion in the coil width direction, the above disadvantage does not occur. Furthermore, as shown in Table 3, the secondary recrystallized structure at the end portion in the coil width direction has an average particle size smaller than that in the central portion in the width direction because secondary recrystallization is promoted on average. Since this is advantageous in increasing the deformation strength, it can be expected that a more excellent space factor will be maintained even after the strain relief annealing.

By the way, such a function and effect that the deformation strength at the end portion in the coil width direction is increased and an excellent space factor is maintained after strain relief annealing is achieved by reducing the grain size of the secondary recrystallization described above. Not only this, but also by lowering the orientation of the secondary recrystallized grains. In other words, the orientation of the secondary crystal grains in the center part in the coil width direction is set to the normal (
0) While the orientation is relatively uniform in the [001] orientation, the orientation of the secondary recrystallized grains at the location where the secondary recrystallization accelerator has been applied tends to deviate from the (110) [001] orientation. Such a tendency is advantageous for deformation, so that the deformation strength is further increased and the deterioration of the space factor after strain relief annealing is suppressed. The present invention has been completed as a result of intensive studies based on the above experiments and survey results.

Hereinafter, with respect to the component composition and the production method of the grain-oriented electrical steel sheet of the present invention, the requirements for obtaining the advantageous effects of the present invention, the range thereof, and the operation will be described in detail. First,
The reason for limiting the component composition of the grain-oriented electrical steel sheet of the present invention will be described. (Si: 1.5 to 7.0 wt%) Si increases the electrical resistance of the product,
It is an effective ingredient for reducing iron loss.
If the content is more than 7.0 wt%, the hardness becomes high and the production and processing become difficult. Therefore 1.5-7.0
It is contained in the range of wt%. (Mn: 0.03 to 2.5 wt%) Mn also has the effect of increasing the electrical resistance like Si, and also has the effect of facilitating hot working in production. For this purpose, it is necessary to contain 0.03 wt% or more, but if it exceeds 2.5 wt%, γ transformation is induced during heat treatment to deteriorate magnetic properties. Therefore, the content should be 0.03 to 2.5 wt%. .

It is essential that all of the above components are contained, but if they are contained as inhibitors and cannot be purified by final finishing annealing and do not deteriorate the magnetic properties, they may be appropriately contained. Can be done. In addition, C, Al, S, N, etc. are harmful components on magnetic properties and can be removed from steel by purifying annealing or decarburizing annealing. preferable. A steel sheet having such a component usually has various coatings on the surface of the steel sheet, but is sometimes used without a coating.

Further, it is necessary for the grain-oriented electrical steel sheet of the present invention that the crystal structure of the grain-oriented electrical steel sheet satisfy any of the following a), b) and c). That is, when the end region in the coil width direction has a fine grain structure of secondary recrystallization, the following a) needs to be satisfied. Here, the fine grain structure of the secondary recrystallization is different from a structure called ordinary secondary recrystallization failure, and the area of each crystal grain is replaced with a circle having an equivalent area in the macro-etched target region. This is a structure of secondary recrystallized grains in which the area ratio of crystal grains having a diameter of 2 mm or less to the region in terms of the diameter of the circle (equivalent circle diameter) is 15% or more. Further, the term “the end region in the coil width direction having the fine grain structure of the secondary recrystallization” means that when a certain distance L is selected and determined from the coil width direction, there is L which becomes the fine grain structure of the secondary recrystallization. That is.

A) For a grain-oriented electrical steel sheet coil, when a certain distance L from the end in the coil width direction is selected and determined, if L is a value exceeding 30 mm for the area from the coil end to L, It is necessary that the appearance of the fine grain structure of the secondary recrystallization is suppressed. When the secondary recrystallization fine grain structure appears even in the edge region where L exceeds 30 mm, it is necessary to perform excessive correction by flattening annealing due to poor shape of the edge region, and the magnetic characteristics resulting from this This results in deterioration of the area and a decrease in the space factor of the end region after the strain relief annealing. Therefore,
In order to suppress the occurrence of such disadvantages, it is necessary to regulate the size of the distance L corresponding to the end region where the secondary recrystallization has a fine grain structure to 30 mm or less. Also,
Even if the end areas regulated in this way are both ends of the coil,
It goes without saying that the effect can be obtained even at one end.

Next, when a fine grain structure of secondary recrystallization is not recognized in the end region in the coil width direction, it is necessary to adopt the following structure b) or c). B) L = 30 mm, that is, the average grain size of the secondary recrystallized grains in the coil width direction end region from the coil end to the width of 30 mm is 4 mm or more, and the average grain size is in the width direction. The average grain size in the central 100 mm width region should be 3 mm or more larger or smaller than 3 mm or less in the structure. It is necessary to further suppress the decrease in the space factor. If the average grain size of the secondary recrystallized grains in the end region is less than ± 3 mm from the value of the average grain size of the secondary recrystallized grains in the central region having a width of 100 mm, flattening annealing is performed. The effect of suppressing the deterioration of the magnetic properties and the decrease in the space factor after the strain relief annealing due to the excessive correction due to the heat treatment does not appear. On the other hand, if the average grain size of the secondary recrystallized grains in this end region is less than 4 mm, the entire secondary recrystallized structure also approaches the state of the fine grained structure, and conversely, the coil shape is deteriorated. Also, it goes without saying that the effect can be obtained even if the end area regulated in this way is both ends of the coil or one end. Note that, here, the average particle size of the secondary recrystallized grains refers to the area of the entire remaining region, as is usually performed, for the remaining region excluding crystal grains having an equivalent circle diameter of 2 mm or less. Is divided by the number of crystal grains occupied by a circle, and is expressed by the diameter of the area of a circle equivalent to this value.

C) The average value αe of the in-plane misorientation angle of the secondary recrystallization in the end region in the coil width direction (where the in-plane misorientation angle is (110) [00] in the steel sheet plane having the [001] orientation.
1], that is, a so-called α angle. ) Is 3 to 20 times larger than the average value αc of the in-plane misorientation angle of the secondary recrystallized grains in the region having a width of 100 mm at the center in the width direction.
The large degree is necessary to suppress the deterioration of the magnetic properties due to the excessive correction by the flattening annealing and the decrease in the space factor after the strain relief annealing in the end region in the coil width direction. The end area at this time is an area having a width from the coil end to 30 mm in the coil width direction. When the average value of the in-plane misalignment angle αe of the area with a width of 30 mm from the end exceeds the value of the average value of the in-plane misalignment angle αc of the central area with a width of 100 mm is less than 3 degrees. Cannot suppress the deterioration of magnetic properties due to excessive correction by flattening annealing and the decrease of the space factor after strain relief annealing in the end region. On the other hand, if αe is larger than αc by more than 20 degrees, the magnetic properties in the end regions are excessively deteriorated, and cannot be used as an electromagnetic steel sheet. Therefore, the value of the average value αe of the in-plane azimuth misalignment angle of the region having a width of up to 30 mm from the end in the coil width direction is calculated at the center of the coil width direction
The value is 3 to 20 degrees larger than the average value αc of the in-plane misorientation angle in the region having a width of 100 mm. Also, it goes without saying that the effect can be obtained even if the end area regulated in this way is both ends of the coil or one end. The average value of the in-plane azimuth deviation angle is obtained by averaging the area of the crystal grains. For example, a method of measuring the crystal orientation at two-dimensional constant intervals and taking the average value is appropriate.

As described above, the defective shape of the end of the coil in the width direction is usually cut off when the product is shipped.
Defects in the shape are often mixed into the product, causing a major trouble in the processing of transformers due to a decrease in space factor or unevenness.In the state after final finish annealing, the above characteristics The realization of a steel sheet that has been provided has improved the product's shape quality, greatly improved the product yield, and eliminated troubles in the processing process of transformers and the like. Note that the grain-oriented electrical steel sheet in the present invention does not mean a slit coil by dividing a product in the width direction, as a matter of course from the object of the invention.

Next, a method for manufacturing a grain-oriented electrical steel sheet according to the present invention will be described. First, the reasons for limiting the component composition of the material will be described. (Si: 1.5 to 7.0 wt%) Si effectively increases the electrical resistance and reduces iron loss, but its effect is poor when it is less than 1.5 wt%, while it exceeds 7.0 wt% Therefore, the workability is deteriorated, and the production itself and the processing of the product become extremely difficult. Therefore, the range is limited to 1.5 to 7.0 wt%. (Mn: 0.03 to 2.5 wt%) Like Si, Mn is not only useful for improving electrical resistance, but also effectively contributes to improving hot workability. Poor,
If the content exceeds 2.5 wt%, γ transformation is induced during heat treatment to cause deterioration of magnetic properties, so the range is limited to the range of 0.03 to 2.5 wt%.

In the steel, a known inhibitor component for inducing secondary recrystallization is contained in addition to the above components.
That is, as inhibitor components, Al, B, Bi, Sb,
Te, Se, S, Sn, P, Ge, As, Nb, Cr, Ti, Cu, Pb, Zn
And In are known. In addition, as an inhibitor additive component, only one type exerts an action alone,
Preferably, two or more kinds of composite additions obtain more preferable results.

As for other components, all known component compositions for grain-oriented electrical steel sheets are suitable, but particularly, the following components have advantageous ranges. When the content of C exceeds 0.120 wt%, it cannot be sufficiently removed by decarburizing annealing, and the magnetic properties tend to deteriorate. On the other hand, 0.010 wt%
If it is less than 30, the effect of improving the structure is inferior, secondary recrystallization tends to be incomplete, and the magnetic properties also tend to deteriorate. Therefore, C is preferably in the range of 0.010 to 0.120 wt%.

The other additional components are not necessarily required to obtain a high magnetic flux density,
For example, the addition of Mo and the like have the effect of improving the surface properties of the steel sheet, so that it is possible to appropriately add Mo.

The steel adjusted to the above-mentioned components is made into a hot-rolled steel sheet by a known hot-rolling method for a grain-oriented electrical steel sheet, and then, if necessary, is subjected to hot-rolled sheet annealing, once or twice or more with intermediate annealing. To the final thickness by cold rolling. It is to be noted that a combination of known warm rolling and inter-pass aging treatment is also effective in the present invention. After the final rolling, it is also possible to provide a linear groove on the surface of the steel sheet for subdividing the magnetic domains. Furthermore, it is also possible to perform a weak decarburization treatment during hot-rolled sheet annealing or intermediate annealing.

Next, primary recrystallization annealing is performed. At this time, if necessary, a decarburizing treatment is simultaneously performed to reduce the C content to a predetermined value or less. After the primary recrystallization annealing, the steel sheet surface is coated with an annealing separating agent, wound into a coil shape, and subjected to final finish annealing. At this time, by winding the coil with a coil winding tension of 3 kgf / mm ² or more, the effect of the present invention is synergistically enhanced. That is, the coil winding tension acts synergistically to improve the shape of the end portion in the coil width direction, which is the object of the present invention, while suppressing buckling due to thermal deformation of the coil during final finish annealing. Is a particularly important technology.

As an annealing separator, MgO is used for forming a forsterite film at the time of final finish annealing.
It is well-known that the main component of a substance other than MgO, such as Al ₂ O ₃ , is used to suppress the formation of a film. It goes without saying that it can be applied. The final finish annealing is annealing for the purpose of secondary recrystallization and purification, and both are usually performed by the same annealing. However, sometimes the annealing is performed separately in two cases, and even in this case, the method of the present invention can be applied. After the final annealing, the unreacted annealing separator is removed, and if necessary, an insulating coating is applied and baked to serve as a flattening anneal to obtain a product. Further, the product may be locally irradiated with a laser or a plasma jet, or may be subjected to a magnetic domain refining treatment by locally introducing a minute strain with a projection roll.

In the manufacturing process of such a grain-oriented electrical steel sheet, before the high-temperature long-time annealing for the purpose of secondary recrystallization, both ends or one end region in the coil width direction are compared with the central region. Improving the shape of the end portion in the coil width direction by performing an additional secondary recrystallization acceleration treatment is the most important component of the method for manufacturing a grain-oriented electrical steel sheet according to the present invention.

Here, the secondary recrystallization accelerating process is a process for speeding up the onset of secondary recrystallization and lowering the temperature.
After winding the coil, a process such as exposing the end face in the width direction to a high-temperature ammonia atmosphere and nitriding is applicable, but the most effective methods are 1) a process for reducing primary recrystallized grains and 2) a strong process. A process that enhances the driving force of primary recrystallized grain growth, such as applying strain to the primary recrystallized grains up to 20% while suppressing the growth of primary recrystallized grains under a restraining force. And 3) strengthen the inhibitory power of inhibitors,
Treatment to promote secondary recrystallization.

Among them, 1) the process of making the primary recrystallized grains finer and 2) the process of strengthening the driving force for the grain growth of the primary recrystallized grains particularly improve the shape of the end portion in the coil width direction. The effect is high and stable, and it is easy and excellent to implement industrially. Such processing is performed locally in the end area in the coil width direction, that is, in the width direction. Furthermore, regarding the above method, to describe a more specific method, as a method of localizing the primary recrystallized grain size, a method of lowering the temperature of the coil width direction end region during annealing of the steel sheet,
In the warm rolling, there are a method of increasing the temperature in the end region in the coil width direction, and a method of suppressing surface decarburization in the end region in the coil width direction during the weak surface decarburization treatment.

As a treatment for imparting strain to the primary recrystallized grains, there is a method in which after the primary recrystallization annealing, strain is imparted to the end region in the coil width direction by a method such as rolling. However, 20%
On the contrary, when a strain exceeding? Is given, fine secondary recrystallized grains increase, and it becomes incompatible.

Further, the steel sheet surface in the end area in the coil width direction is covered with plating to suppress the disappearance of the inhibitor from the steel sheet surface before the secondary recrystallization, or the coil width before or after the application of the annealing separating agent. There is a method of using a suppressive strength enhancer such as applying a suppressive strength enhancer to a direction end region or adding a suppressive strength enhancer to an annealing separator. Here, the suppressive power enhancer is, for example, selenate or selenide.
Inhibitor components such as selenium-containing substances, tellurium-containing substances, phosphorus-containing substances such as calcium phosphate and ammonium phosphate, tin-containing substances such as tin oxide, and nitrides such as iron nitride and manganese nitride Among the contained substances, it is a general term for substances that particularly promote secondary recrystallization and suppress the appearance of secondary recrystallization of fine crystal grains of 2 mm or less.

It is more preferable that the width of the end region to be subjected to such a secondary recrystallization acceleration treatment be 30 mm or less, since the effect of improving the shape of the end portion in the coil width direction becomes remarkable.

The structure of secondary recrystallization formed when the above-described additional secondary recrystallization acceleration treatment is applied to both end regions or one end region in the coil width direction is as follows: Takes various forms in the balance between the inhibitor of the steel sheet and the primary recrystallized grain size. That is, when the secondary recrystallization acceleration treatment is performed when the inhibitor of the steel sheet after the primary recrystallization is strong, and thus the primary recrystallization grain size is small, the in-plane misorientation angle α of the secondary recrystallized grains increases. Changes to In addition, the inhibitor of the steel sheet after primary recrystallization is strong,
Further, when the secondary recrystallization acceleration treatment is performed when the primary recrystallization particle size is large, the average particle size of the secondary recrystallization decreases. Furthermore,
When the inhibitor of the steel sheet after the primary recrystallization is weak, and thus the primary recrystallization particle size is large, the secondary recrystallization acceleration treatment reduces the fine grain structure of the secondary recrystallization. Further, when the secondary recrystallization acceleration treatment is performed when the inhibitor of the steel sheet after the primary recrystallization is weak and the primary recrystallization particle size is small, the average particle size of the secondary recrystallization increases. As described above, various forms of the secondary recrystallized structure appear depending on the state of the structure of the grain-oriented electrical steel sheet after the primary recrystallization annealing, but all improve the shape defect in the end portion in the coil width direction. It is effective for

[0056]

[Example] (Example 1) C: 0.08 wt%, Si: 3.32 wt%, Mn: 0.07 wt%, Al: 0.02
Two 20t steel slabs containing wt%, Sb: 0.025wt% and N: 0.008wt%, the balance being iron and unavoidable impurities, were heated to 1420 ° C, and then heated to 2.22mm thickness by the usual method. It was a rolled steel sheet. Next, after annealing the hot-rolled sheet at 1000 ° C. for 30 seconds, it was pickled and cold-rolled to a thickness of 1.6 mm. After that, intermediate annealing was performed at 1080 ° C for 40 seconds. At this time, one was annealed at a uniform temperature of 1080 ° C in the coil width direction (comparative example), and the other one was at both ends in the coil width direction. The temperature in the region from the end to 100 mm from the end was lowered by 30 ° C. by the furnace shield plate to 1050 ° C. and annealed (invention example). Thereafter, both were warm-rolled at a steel sheet temperature of 200 ° C. to a final thickness of 0.22 mm. Then, after degreasing, decarburizing annealing was performed at 850 ° C for 2 minutes, followed by 5%
Of TiO ₂ and 2% of SrSO ₄ was applied as an annealing separator at 12 g / m ² , and at this time, each coil was equally divided into two, and one was coiled at 2 kgf / mm ² The other was wound into a coil at 6 kgf / mm ² . When the average grain size of the primary recrystallized grains at this time was measured, all the coils were in the range of 8 to 9 μm at the center in the coil width direction.

Next, final finish annealing was performed. The condition was that the temperature was raised to 850 ° C. at a rate of 30 ° C./h in N ₂ , and the temperature was maintained at 850 ° C. for 25 hours. _In a mixed atmosphere of ₂ and 75% H _2, the temperature was raised to 1200 ° C at a rate of 15 ° C / h,
After further keeping in H ₂ for 5 hours, the temperature was lowered. Then, after removing the unreacted annealing separating agent, these coils were coated with a tension coating containing 50% colloidal silica, and 800 ° C. was used as a flattening annealing while applying a tension of 1.0 kgf / mm ^2. For 1 minute.

The magnetic properties of these products and the average shape defect factor HD in the end area in the width direction of the coil were measured, and the average value of each coil in the entire length in the longitudinal direction was obtained. In addition, a large number of steel sheets of 300 mm width and 1 m length in the rolling direction were cut out from both ends in the coil width direction, 100 sheets of these were laminated, and the space factor after strain relief annealing at 800 ° C for 3 hours was measured. It was measured. Table 4 shows these measured values. Further, the crystal structure after macro-etching at both end regions (30 mm width at both ends) in the coil width direction is also shown in Table 4 in comparison with a crystal structure at 100 mm width at the center region in the width direction. As is clear from Table 4, when the grain-oriented electrical steel sheet of the present invention is used, the magnetic properties and the shape of the coil width direction end are excellent, and the space factor of the steel sheet in the coil end area is also a good value. Is obtained.

[0059]

[Table 4]

(Example 2) C: 0.04 wt%, Si: 3.05 wt%, Mn: 0.06 wt%, S: 0.01
6 wt%, Cu: 0.15 wt%, Mo: 0.010 wt% and Sb: 0.015
wt%, balance is iron and unavoidable impurities
Five 20-ton steel slabs were heated to 1400 ° C, and then turned into 2.4 mm-thick hot-rolled steel sheets by an ordinary method. Next, after the hot rolled sheet was annealed at 900 ° C. for 30 seconds, it was pickled, cold rolled to an intermediate sheet thickness of 0.74 mm, and then subjected to intermediate annealing at 1000 ° C. for 50 seconds. Furthermore, after a final thickness of 0.27 mm was obtained by cold rolling, degreasing was performed, and decarburization annealing was performed at 850 ° C. for 2 minutes.
An annealing separator containing O 2 as a main component was applied at 10 g / m ² . Thereafter, one coil was wound into a coil with a tension of 4 kgf / mm ² (conventional example). For the other four coils, apply 1 g / m ^{2 of} monobasic ammonium phosphate to one side of the end in the coil width direction in the width direction of 10 mm, 20 mm, 30 mm and 40 mm, respectively, and apply a tension of 4 kgf / mm ² It was wound up in a coil shape (inventive example).

These coils were placed at the lower end in contact with the base plate at the end coated with 2 g / m ^{2 of} monobasic ammonium phosphate, and subjected to a final finishing annealing in N ₂ at 850 ° C.
The temperature was raised at a rate of 30 ° C./h, then in a 100% H ₂ atmosphere to 1200 ° C. at a rate of 25 ° C./h, and further in H ₂
After holding for 5 hours, the temperature was lowered. The coils were then coated with a tension coating containing 60% colloidal silica after removal of unreacted annealing separator and 0.7 kgf /
1 mm at 800 ℃ with flattening annealing while applying a tension of ² mm2
The product was baked for a minute and subjected to a magnetic domain refining treatment using a plasma jet.

The magnetic properties of these products and the average shape defect factor HD in the end portion in the width direction of the coil in contact with the base plate were measured, and the average value of each coil in the entire length in the longitudinal direction was obtained. Also, a large number of steel plates of 300 mm width and 1 m length in the rolling direction were cut out from both ends in the coil width direction on the side in contact with the base plate, and 100 of these were laminated and subjected to strain relief annealing at 800 ° C for 3 hours. Was measured. Table 5 shows these measured values. Table 5 also shows the crystal structure after macro-etching of both end regions (30 mm width at both ends) in the coil width direction on the side in contact with the base plate in comparison with a crystal structure having a width of 100 mm in the center region in the width direction. The area ratio of the fine-grained structure was less than 3% at the center in the coil width direction, but the fine-grained structure was developed from the end of the coil in the end region. Therefore, the distance L15 (average value of both end regions) in the width direction from the coil end where the area ratio of the crystal grains having a grain size of 2 mm or less is 15% was obtained for each product and is shown in Table 5. FIG. 6 shows the relationship between L15 of each product and the end shape defect factor. As is clear from Table 5 and FIG. 6, when the grain-oriented electrical steel sheet of the present invention is used, the magnetic properties and the shape of the end portion in the coil width direction are excellent, and the space factor of the steel sheet in the coil end area is also high. Good values are obtained.

[0063]

[Table 5]

(Example 3) C: 0.08 wt%, Si: 3.37 wt%, Mn: 0.07 wt%, Al: 0.02
wt%, S: 0.015 wt%, Sn: 0.15 wt%, N: 0.008 wt%
And the balance is iron and unavoidable impurities, weight 20t
After heating three steel slabs at 1400 ° C,
A hot-rolled steel sheet having a thickness of 2 mm was used. Next, after hot-rolled sheet annealing at 1200 ° C. for 30 seconds, the sheet was pickled and warm-rolled at a steel sheet temperature of 200 ° C. to a final sheet thickness of 0.26 mm. Next, after the degreasing treatment, as a magnetic domain subdivision treatment, a linear groove having a width of 50 μm and a depth of 25 μm was provided at an angle of 15 degrees from the coil width direction and a repetition pitch in the coil longitudinal direction: 4 mm. Decarburization annealing at 850 ° C for 2 minutes, followed by N ₂ containing 5% ammonia
Nitriding was performed at 800 ° C in an atmosphere to further increase the nitrogen content in the steel by 100 to 150 ppm. The average primary crystal grain size after decarburization annealing was all in the range of 16 to 17 μm. Thereafter, 12 g / m ^{2 of} MgO to which 5% TiO ₂ and 2% SrSO ₄ were added was applied as an annealing separating agent. At this time, each coil was equally divided into two parts, one of which was 2 kgf / mm ² And the other was coiled at 6 kgf / mm ² . When the average particle size of the primary recrystallized grains at this time was measured, each coil was 8 to 9 μm
Was within the range.

[0065] Then, wound into a single coil 14 g / ^{01 2} a MgO added with TiO ₂ 7% as annealing separator, coiled tension was uniformly applied to the coil width direction 2 kgf / mm ² (Conventional example). One more coil is located in the end area in the coil width direction.
The width of 50 mm 5 percent FeN and 7% of MgO was added TiO ₂
The remaining area was coated with MgO containing 7% TiO ₂ at 14 g / m ² as an annealing separator, and wound into a coil at a tension of 2 kgf / mm ² (Invention Example 1). The remaining one coil has 10% Fe in the width of 50 mm in the end area in the coil width direction.
MgO with N and 7% TiO ₂ added, 7% in the remaining area
MgO to which TiO ₂ was added was used as an annealing separator
g / m ^{2 was} applied and wound into a coil with a tension of 2 kgf / mm ² (Invention Example 2).

These coils were heated in N ₂ to 850 ° C. at a rate of 30 ° C./h as final finish annealing.
After holding at 25 ° C for 25 hours, the temperature was raised to 1200 ° C at a heating rate of 15 ° C / h in a mixed atmosphere of 25% N ₂ and 75% H ₂ , and further kept in H ₂ for 5 hours. , Temperature dropped. The coils were then stripped of unreacted annealed separating agent and then applied with a tension coating containing 50% colloidal silica, for 1.5 kg.
at 800 ° C. also serves as a flattening annealing while adding tension of f / mm ²
Bake for 1 minute to make the product.

The magnetic properties of these products and the average shape defect factor HD in the end portions in the width direction of the coil were measured, and the average value of each coil in the entire length in the longitudinal direction was obtained. In addition, a large number of steel sheets of 300 mm width and 1 m length in the rolling direction were cut out from both ends in the coil width direction, 100 sheets of these were laminated, and the space factor after strain relief annealing at 800 ° C for 3 hours was measured. It was measured. Table 6 shows these measured values. Further, the crystal structure after macro-etching at both end regions (30 mm width at both ends) in the coil width direction is also shown in Table 6 in comparison with the crystal structure at 100 mm width at the center region in the width direction. As is clear from Table 6, when the grain-oriented electrical steel sheet of the present invention is used, the magnetic properties and the shape of the coil width direction end are excellent, and the space factor of the steel sheet in the coil end area is also a good value. Is obtained.

[0068]

[Table 6]

(Example 4) C: 0.05 wt%, Si: 3.17 wt%, Mn: 0.07 wt%, Al: 0.02
Five steel slabs, each containing 0.25 wt% and 0.025 wt% of Sb, the balance being iron and unavoidable impurities, were heated to 1160 ° C., and then turned into 2.4 mm-thick hot-rolled steel sheets. Next, after the hot rolled sheet was annealed at 900 ° C. for 30 seconds, it was pickled and warm rolled at a steel sheet temperature of 150 ° C. to a final thickness of 0.34 mm. Next, after degreasing, decarburizing annealing was performed at 820 ° C. for 2 minutes. The average primary crystal grain size at this time was in the range of 14 to 21 μm. Then one of these coils stays at 2%
Apply an annealing separator with tin oxide added to it and wind it into a coil with a tension of 5 kgf / mm ² (conventional example). For the other four coils, apply a roll pressure to a 50 mm wide area at both ends in the coil width direction. Apply 1.0%, 2.5%, 4.3%, 5.7% deformation, respectively, and apply an annealing separator with tin oxide content increased to 5% to both end areas to increase the suppression power as an annealing separator. It was wound around a coil with a tension of 5.0 kgf / mm ² (invention example).

These coils were treated with N ₂ as final finish annealing.
Temperature up to 850 ° C at a rate of 30 ° C / h, then 20%
At a rate of 25 ° C./h in a mixed atmosphere of N ₂ and 80% H ₂
The temperature was raised to 00 ° C., further kept in H ₂ for 5 hours, and then lowered. Thereafter, these coils to remove the annealing separator of the unreacted tension coating containing 60% colloidal silica was applied, serves to 800 ° C. The flattening annealing while adding tension of 1.5 kgf / mm ² For 1 minute.

The magnetic properties of these products and the average shape defect factor HD in the end portions in the width direction of the coil were measured, and the average value of each coil in the entire length in the longitudinal direction was obtained. In addition, a large number of steel sheets of 300 mm width and 1 m length in the rolling direction were cut out from both ends in the coil width direction, 100 sheets of these were laminated, and the space factor after strain relief annealing at 800 ° C for 3 hours was measured. It was measured. Table 7 shows these measured values. Further, the crystal structure after macro-etching in both end regions (width 30 mm at both ends) in the coil width direction is also shown in Table 7 in comparison with a crystal structure having a width 100 mm width in the center region in the width direction. As is clear from Table 7, when the grain-oriented electrical steel sheet of the present invention is used, the magnetic properties and the shape of the end portion in the coil width direction are excellent, and the space factor of the steel sheet in the coil end area is also a good value. Is obtained.

[0072]

[Table 7]

[0073]

Thus, according to the present invention, the shape of the end portion in the coil width direction in the state of the steel sheet coil after the final finish annealing can be achieved without impairing the excellent magnetic properties of the product coil of the grain-oriented electrical steel sheet. A good space factor after strain relief annealing in the coil end area can be obtained, and defective shapes are often mixed into the product, leading to a decrease in the space factor or unevenness in the processing process of transformers due to unevenness. The problem of causing major troubles is solved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a temporal change of a temperature difference due to a difference in a position between a central portion and an upper end portion in a coil during final finish annealing.

FIG. 2 is an explanatory diagram of a shape defect at a width direction end of a coil or a product coil after final finish annealing, a wave height H as an evaluation index thereof, and a distance D from the width end of the shape defect.

FIG. 3 is a diagram showing the effect of a difference in average crystal grain size of a decarburized annealed sheet on a difference in strength of high-temperature deformation based on a measurement result of a high-temperature load tensile test.

FIG. 4 is a diagram showing a change in tensile hot deformation rate depending on a crystal grain size.

FIG. 5 is a diagram showing an area ratio of crystal grains having a grain size of 2 mm or less in a macrostructure of steel plates a and c in relation to a distance from an end in a coil width direction.

FIG. 6 is a diagram showing a relationship between a distance L15 from the coil end to the width direction where the area ratio of crystal grains having a grain size of 2 mm or less is 15% and an end shape defect coefficient.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Kunihiro Senda 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. MA03 PA09 RA04 SA02 SA03 TA01 TA04 5E041 AA02 AA11 AA19 CA02 HB11 NN01 NN06 NN17

Claims (7)

[Claims] 1. Si: 1.5 to 7.0 wt%, Mn: 0.03 to 2.5 wt%
%, The area ratio of crystal grains having a grain size of 2 mm or less in the region from the end determined by selecting a fixed distance in the width direction from the end in the coil width direction is occupied in the region.
A low iron loss directional electrical steel sheet having an excellent shape at an end portion in a coil width direction, wherein the predetermined distance L of 15% is 30 mm or less from both end portions or one end portion. 2. Si: 1.5 to 7.0 wt%, Mn: 0.03 to 2.5 wt%
%, The average value αe of the in-plane misorientation angle of crystal grains having a grain size of more than 2 mm in a region up to 30 mm from both ends or one end in the coil width direction in the direction of the coil width. , The particle size in the area of 100 mm width in the center of the coil width direction
3 to 20 than the in-plane misorientation angle αc of crystal grains exceeding 2 mm
Low iron loss grain-oriented electrical steel sheet with an excellent shape at the end in the coil width direction characterized by a large degree. 3. Si: 1.5 to 7.0 wt%, Mn: 0.03 to 2.5 wt%
%, The average grain size of crystal grains exceeding 2 mm in the region up to a distance of 30 mm from both ends or one end in the coil width direction is 4 mm or more, and 2 mm particle size in 100 mm width area at the center of coil width direction
3 mm or smaller than the average grain size of crystal grains exceeding 3 mm
A low iron loss grain-oriented electrical steel sheet having an excellent shape at an end portion in a coil width direction characterized by being larger than the above. 4. Si: 1.5 to 7.0 wt%, Mn: 0.03 to 2.5 wt%
% Of the grain-oriented electrical steel sheet coil and subjected to high-temperature long-time annealing including secondary recrystallization, before the high-temperature long-time annealing, in the region at both ends in the width direction of the coil or at one end region. An additional secondary recrystallization accelerating process as compared with the central portion in the width direction to reduce the generation frequency of crystal grains having a grain size of 2 mm or less in the edge portion. Method for producing low iron loss grain-oriented electrical steel sheet with excellent part shape. 5. The shape of the end portion in the coil width direction according to claim 4, wherein the secondary recrystallization accelerating process is a process of refining primary recrystallized grains or a process of enhancing a driving force for growing grains of primary recrystallized grains. Manufacturing method of low iron loss grain oriented electrical steel sheet. 6. The winding tension for forming a coil is 3
method of manufacturing low core loss oriented electrical steel sheet excellent in shape of the coil end portion in the width direction of the claims 4 or 5, wherein the kgf / mm ² or more. 7. The coil width direction end according to claim 4, 5 or 6, wherein the region to be subjected to the secondary recrystallization acceleration treatment is at least 30 mm in the coil width direction from both ends or one end of the coil. Manufacturing method of low iron loss oriented electrical steel sheet with excellent shape.