JPH06220590A - High silicon steel sheet excellent in workability - Google Patents

Abstract

PURPOSE:To provide an inexpensive high silicon steel sheet excellent in workability. CONSTITUTION:This high silicon steel sheet has a composition containing, by weight, 4-10% Si, containing, preferably, <=0.01% C, <=0.5% Mn, <=0.01% P, <=0.01% S, <=0.2% Sol.Al, <=0.01% N, and <=0.02% O, and having the balance Fe with inevitable impurities or a composition containing 4-10% (Si+Al) and preferably containing the C, Mn, P, S, N, and O by the above quantities, respectively. In this steel sheet, O concentration in the elements segregating in crystalline grain boundaries is <=30at% and S concentration in the elements segregating in crystalline grain boundaries is <=0.2at%, and further preferably, sheet thickness is <=0.5mm and average grain size viewed from sheet surface is <=2.0mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high silicon electromagnetic steel sheet used as a core material for transformers and motors.

2. Description of the Related Art Silicon is generally added to magnetic steel sheets, which are widely used as a core material for motors and transformers, in order to control texture and increase specific resistance. Silicon is 6.
The iron alloy containing 5 wt% exhibits the most excellent soft magnetism because the magnetostriction becomes almost zero, but the material becomes brittle when the added amount of silicon becomes large. Therefore, high-silicon steel containing 4 wt% or more of silicon is usually used. It is impossible to make a thin steel sheet by the rolling method. On the other hand, in recent years, as a method for obtaining a high-silicon thin steel sheet,
A melt quenching method that directly casts a thin plate from the molten state (for example,
Japanese Patent Publication No. 60-32705), a method of applying a special rolling method (for example, Japanese Patent Publication No. 3-80846), a so-called siliconizing method for enriching Si in a low-Si steel plate obtained by rolling (for example, Proposal No. 2-60041) and the like have been proposed, and especially the siliconizing method has been industrially put to practical use.

By the way, in order to actually use the high silicon steel sheet manufactured by the above-mentioned method for a motor or a transformer, it is necessary to add punching, shearing or bending to the steel sheet. However, since the high silicon steel plate is brittle, there is a problem that cracks and defects occur at punching and shearing end faces, and cracks easily occur during bending. Several proposals have hitherto been made for the purpose of improving the processing of such a high silicon steel sheet.

For example, in Japanese Patent Publication No. 61-15136,
A high silicon steel strip excellent in workability and magnetic properties can be obtained because the crystal grain size is 1 to 100 μm and the crystal grains are columnar crystals grown perpendicularly to the surface of the thin plate, and the ordered lattice is substantially absent. I am trying. Also, JP-A-62-27072
In No. 3, it is stated that a high silicon steel sheet having substantially good workability can be manufactured by forming the product into a product shape in the rolled structure and then annealing. Furthermore, JP-A-4-16
According to No. 5050, Mn is added to suppress the adverse effect of solid solution S and the orientation integration degree of crystal grains is increased to produce a highly silicon-oriented silicon steel sheet having excellent workability.

[0004]

However, among these proposals, Japanese Patent Publication No. 61-15136 discloses a crystal grain size of 100.
If the thickness is more than μm, the effect cannot be obtained, and in order to make the ordered phase substantially absent in high silicon steel, 90
Since it is necessary to perform quenching such as water quenching from 0 ° C. or higher, this is a technique with difficulty in the manufacturing process. Further, in the method disclosed in Japanese Patent Laid-Open No. 62-270723, high temperature annealing is required after working because it has a rolling structure during working, and one process is added considering the current manufacturing process of transformers and motors. Therefore, it is not economically preferable. Further, in Japanese Unexamined Patent Publication No. 4-165050, it is necessary to have a high orientation integration, but it is difficult to obtain a high integration degree in view of the stability of secondary recrystallization using an inhibitor, and
This technique has a drawback that it cannot be applied to non-oriented silicon steel sheets.

The present invention has been made in view of the above problems of the prior art, and considers the workability of the high-silicon electrical steel sheet required in the steps of punching, shearing, bending, etc. from the viewpoint of the material and the economical efficiency. It is an object of the present invention to provide a high-silicon electrical steel sheet that is inexpensive and has excellent workability, that is, has few cracks and defects in punching and shearing end faces, or can have a small bendable radius in bending. To do.

[0006]

High silicon steel sheets have a large amount of silicon and the mother phase is inherently brittle, and it has heretofore been thought that improvement in workability is almost impossible. The present inventors have conducted various experimental studies with the aim of improving the workability of high silicon steel sheets, and investigate the workability of various high silicon steel sheets with varying dew point and oxygen concentration in the final heat treatment atmosphere. Among them, it was discovered that there is a steel having the same silicon content but relatively good workability as compared with other steel sheets. FIG. 1 shows the test result in that case. In this test, the degree of vacuum was changed to change the dew point and oxygen concentration in the annealing atmosphere. In the figure, the horizontal axis represents this degree of vacuum, and the vertical axis represents the workability index in a three-point bending test (a test in which the sample is pushed in by the method shown in FIG. 2 and the stroke distance at which the sample can be pushed in without cracking is measured). The amount of pushing until the specimen breaks is shown. Annealing was performed under the conditions of 1200 ° C. for 15 minutes under each vacuum degree. From this test result, it was found that the better the degree of vacuum, the better the workability.

A detailed study of the fracture mechanism of high silicon steel based on these samples revealed that the morphology of the fracture surface had a strong correlation with the workability, and specifically, those with poor workability were found. It was revealed that many grain boundary fracture surfaces of crystal grains appeared, while those of excellent workability showed many cleavage fracture surfaces.
In addition, when the segregation element concentration of the grain boundary fracture surface was investigated by Auger electron spectroscopy between the samples with excellent workability and the sample with inferior workability, the samples with excellent workability generally have a low oxygen concentration at the crystal grain boundaries and It was revealed that the sample with high oxygen concentration in the interface was inferior in workability.

The present inventors have tried to clarify factors other than the grain boundary oxygen concentration, which are correlated with the workability, by further examining the grain boundaries in detail. That is, the influence of various grain boundary segregation elements on the workability was investigated for a sample group in which the grain boundary oxygen concentration was constant. As a result, it was found that sulfur at the grain boundaries had a significant effect on workability, independent of the effect of oxygen. FIG. 3 shows Si: 6.49w
t%, Mn: 0.005 wt%, S: 0.0015 wt
%, O: 0.0022 wt% of a sample having a plate thickness of 0.35 mm was heat-treated in an N ₂ atmosphere containing 0.1 vol% H ₂ S, and the three-point bendability of the sample after heat treatment ( Indentation amount in the above three-point bending test),
It shows the relationship with the sulfur concentration detected at grain boundaries by Auger electron spectroscopy. The total amount of sulfur in the sample after the heat treatment was almost constant within the analytical error. Further, the oxygen concentration at the grain boundaries measured by Auger electron spectroscopy was in the range of 3 to 5 at%. According to FIG. 3, the workability has a strong correlation with the sulfur concentration in the crystal grain boundaries, and it can be inferred that the sulfur in the crystal grain boundaries deteriorates the workability. The detailed mechanism of the strong correlation between the grain boundary sulfur concentration and the workability is unknown, but since the sulfide forming element such as Mn is not contained in the grain boundary, sulfur is probably a solid solution. It is considered that they exist in the grain boundary in the state of being formed.

Further, although it is easy to control the crystal grain size by changing the annealing temperature, it was found in the above-mentioned test that the workability also greatly changes when the annealing temperature is changed. As described above, the present inventors have found that the workability of a high-silicon steel sheet, which has been conventionally considered to be basically inferior in workability, has an extremely large correlation with the properties of grain boundaries, and it is necessary to control this. It was found that a high silicon steel sheet excellent in workability can be obtained by the above.

The present invention has been made on the basis of such findings and has the following constitution. (1) Si: 4 to 10 wt% is contained, and the O concentration in the grain boundaries (O concentration in the elements segregated in the grain boundaries) is 3
A high silicon magnetic steel sheet having an excellent workability of 0 at% or less and an S concentration at a crystal grain boundary (S concentration in an element segregated at the crystal grain boundary) of 0.2 at% or less. (2) C: 0.01 wt% or less, Si: 4 to 10 wt
%, Mn: 0.5 wt% or less, P: 0.01 wt% or less, S: 0.01 wt% or less, Sol. Al: 0.2w
t% or less, N: 0.01 wt% or less, O: 0.02 wt
% Or less, the balance consists of Fe and unavoidable impurities, and the O concentration in the crystal grain boundaries (O concentration in the elements segregated in the crystal grain boundaries) is 30 at% or less, the S concentration in the crystal grain boundaries (in the elements segregated in the crystal grain boundaries). S silicon concentration) is 0.2 at% or less, and is a high-silicon electrical steel sheet with excellent workability. (3) Si + Al: 4 to 10 wt% is contained, the O concentration in the crystal grain boundary (O concentration in the element segregated in the crystal grain boundary) is 30 at% or less, and the S concentration in the crystal grain boundary (segregated in the crystal grain boundary). A high silicon electrical steel sheet having an excellent workability and having an S concentration in the element) of 0.2 at% or less. (4) C: 0.01 wt% or less, Si + Al: 4-1
0 wt%, Mn: 0.5 wt% or less, P: 0.01 wt
% Or less, S: 0.01 wt% or less, N: 0.01 wt%
Hereinafter, O: 0.02 wt% or less, consisting of balance Fe and unavoidable impurities, O concentration in the crystal grain boundary (O concentration in the element segregated to the crystal grain boundary) is 30 at% or less, S concentration in the crystal grain boundary (crystal (S concentration in elements segregated at grain boundaries)
Of 0.2 at% or less is a high-silicon electrical steel sheet with excellent workability. (5) In the steel plates of (1) to (4) above, the plate thickness is 0.5 mm or less, and the average crystal grain size viewed from the plate surface is 2.0 m.
A high-silicon electrical steel sheet with an excellent workability of m or less.

[0011]

The details of the present invention will be described below together with the reasons for limitation. When Si is added in an amount of approximately 6.5 wt%, the magnetostriction becomes zero and the most excellent soft magnetism is exhibited. If Si is less than 4 wt%, the desired magnetic properties as a high silicon steel sheet cannot be obtained, and
The workability of the steel sheet is also not a particular problem. On the other hand, Si is 10
When it exceeds wt%, the saturation magnetic flux density is significantly reduced. Therefore, Si is 4 to 10 wt%. It is also possible to replace a part of Si with Al, and in this case, it is necessary to regulate the amount of Si + Al. Si + Al is 4w
If it is less than t%, the magnetic properties aimed by the present invention cannot be obtained,
Further, the workability of the steel sheet is not a particular problem. On the other hand, Si
When + Al exceeds 10 wt%, the saturation magnetic flux density is significantly reduced. Therefore, when a part of Si is replaced with Al, Si + Al: 4 to 10 wt%.

C is an element harmful to soft magnetism, and C
If it exceeds 0.01 wt%, a so-called aging deterioration phenomenon occurs in which the soft magnetism deteriorates with time. Therefore, C is 0.01 wt%
The following is preferable. Mn combines with S to MnS
And has the effect of improving hot workability in the slab stage. However, when Mn exceeds 0.5 wt%, the saturation magnetic flux density is greatly reduced, which is not suitable. Therefore, Mn is preferably 0.5 wt% or less.

P is an element that deteriorates the soft magnetic characteristics,
The content is preferably as low as possible. Since P is 0.01 wt% or less and the adverse effect thereof can be substantially ignored, P is preferably 0.01 wt% or less. Since S is an element that increases brittleness during hot rolling and also deteriorates soft magnetic properties, its content is preferably as low as possible. As will be described later, the most important requirement in the present invention is the sulfur concentration at the grain boundary, but the sulfur amount described here is the total sulfur amount including the grain boundary and the inside of the grain. Economy and S is 0.01w
If it is t% or less, the adverse effect can be substantially ignored, so S is preferably 0.01 wt% or less.

Al has a function of cleaning steel by deoxidation and also has a function of increasing electric resistance in terms of magnetic characteristics. In steel containing 4 to 10 wt% of Si, Si improves the magnetic properties, and Al only has to perform the deoxidizing action of steel. Al is preferably 0.2 wt% or less. On the other hand, when replacing a part of Si with Al, as described above, Si + Al is 4 to 10 w.
t%. N is an element that deteriorates the soft magnetic characteristics,
The content thereof is preferably as low as possible because it also causes a change in the magnetic properties over time due to aging. It is preferable to set N to 0.01 wt% or less because the economical efficiency and the adverse effect thereof can be substantially ignored if N is 0.01 wt% or less.

O is an element that deteriorates the soft magnetic characteristics,
The content is preferably as low as possible. In the present invention, the oxygen concentration at the grain boundary is defined, but the O amount here is the total O amount including the grain boundary and the inside of the grain. As will be described later, the present invention relates to O and S which are unavoidably contained in the steel sheet.
It is possible to obtain excellent workability by controlling the concentration at the grain boundary. However, if the amount of O in the steel sheet increases, oxygen appears to exist both inside the grain and at the grain boundary regardless of heat treatment conditions. Therefore, it becomes difficult to control the grain boundary oxygen concentration to 30 at% or less. When the amount of O in the steel sheet is 0.02 wt% or less, it is relatively easy to selectively control the location (intragrain or grain boundary) where oxygen is present depending on the heat treatment conditions (for example, vacuum degree of heat treatment atmosphere). And therefore O
Is preferably 0.02 wt% or less. On the other hand, O
There is no particular limitation on the lower limit of the above, and simple reduction of the O amount does not lead to reduction of the grain boundary oxygen concentration. However, excessive reduction of O leads to high cost, and therefore it is not a good idea to reduce O to less than 0.0005 wt% from the economical point of view. In addition to the above components, there are cases where Cr, Ni, Cu, Sn, Mo, etc. are contained as inevitable impurities in the steel, and the effect of the present invention is impaired even if each of them is contained up to about 0.03 wt%. I can't.

In the steel sheet of the present invention, the sulfur concentration at the grain boundaries (sulfur concentration in the elements segregated at the grain boundaries) is 0.2 at% (at
Omic%) or less, which is the most important requirement in the present invention. Here, the amount of sulfur at the grain boundaries means the sulfur content (a in the elements segregated at the grain boundaries.
t%). Usually, an Auger electron spectroscope is used to measure the amount of sulfur. In this measurement, the sample was destroyed in a vacuum container kept at a vacuum degree of 1 × (1/10 ⁹ ) torr or less, and the Auger electron was spectroscopically observed while observing a clean grain boundary fracture surface not polluted by the atmosphere. This makes it possible to analyze elements on a clean grain boundary fracture surface.

In general, when the element is quantified by Auger electron spectroscopy, the following method is used (see "Practical Auger electron spectroscopy for users", Kyoritsu Shuppan 1989). That is, when quantifying an element on the material surface, the measured Auger electron intensity (differentiated with respect to energy, indicated by the peak height) and an index showing the Auger electron emission efficiency of each element It is calculated as follows using a relative sensitivity of [X] (at%) = {(X / x) / [(A / a) + (B / b) + (C / c) + ... + (X / x) + ... ] × 100 However, A, B, C, D, ...: Auger electron intensity of each element a, b, c, d, .....: Relative sensitivity of each element

The energy position for measuring the Auger electron intensity is determined by the element. For example, Fe is the peak on the highest energy side of the three LMM transitions, O is the KLL transition, C is the KLL transition, and S is the S peak. Uses LVV transitions. Also, the relative sensitivity has already been obtained for the transition of each element, and the value is described in the above document, but in the apparatus of Phi, Fe: 0.220, C:
Values of 0.140, O: 0.400, S: 0.750 are used. As described above, the quantitative value of the element is generally obtained from the Auger electron spectroscopy result, and the present invention also employs this method to quantify the element at the crystal grain boundary. As described above, the inventors of the present invention searched for a grain boundary between a material with excellent workability and a material with poor workability by such a method, and performed elemental analysis at this grain boundary. The inventors have found that the sulfur concentration has an extremely large correlation with the processability.

As an example, for a high silicon steel sheet having a thickness of 0.1 mm having the chemical composition shown in Table 1 and having substantially the same oxygen concentration at the crystal grain boundaries measured by Auger electron spectroscopy, tensile elongation and Auger electron FIG. 4 shows the result of examining the correlation with the sulfur concentration of the crystal grain boundary measured by spectroscopy.
According to the figure, the tensile elongation is better as the sulfur concentration in the crystal grain boundary is obviously lower. Among the samples of this test, those having a tensile elongation of 3% or more caused plastic deformation. Further, when the fracture surface was observed with a scanning electron microscope, it was found that those with better tensile elongation had more cleavage fractures than intergranular fractures, while those with poorer tensile elongation had a greater tendency for intergranular cracking. It was Conventionally, it has been considered that such a high silicon steel sheet does not cause plastic deformation.
It was revealed that plastic deformation occurs when the sulfur concentration at the crystal grain boundary is 0.2 at% or less. From the above, in the present invention, the sulfur concentration at the crystal grain boundary is 0.2 at.
% Or less.

The present invention not only regulates the sulfur concentration at the grain boundaries as described above, but also sets the oxygen concentration at the grain boundaries (oxygen content in the elements segregated at the grain boundaries) to 30 at.
% (Atomic%) or less. That is, the effect of reducing the grain boundary sulfur concentration can be obtained only when the grain boundary oxygen concentration is sufficiently low, and therefore the grain boundary oxygen concentration needs to be 30 at% or less. Fig. 5 shows Si: 6.66 wt%, S: 0.001 wt%
%, Sol. Al: 0.001 wt%, O: 0.002
With respect to steel plates having a composition of 5 wt% and different oxygen concentrations at grain boundaries (sheet thickness 0.35 mm), the sulfur concentration at the grain boundaries and the three-point bendability (indentation amount in the above-mentioned three-point bending test) It shows the relationship of. According to this, when the grain boundary oxygen concentration is 30 at% or less, the correlation between the grain boundary sulfur concentration and the three-point bendability is recognized, but the grain boundary oxygen concentration is 30
When it exceeds at%, even if the grain boundary sulfur concentration is reduced to 0.2 at% or less, the three-point bendability hardly changes. Therefore, in the present invention, the grain boundary oxygen concentration is defined as 30 at% or less, preferably 15 at% or less.

Further, in addition to the effects of the sulfur concentration and the oxygen concentration at the crystal grain boundaries as described above, the crystal grain size also affects the workability, and the average crystal grain size seen from the plate surface is 2.0 m.
It was revealed that the workability was further improved when the thickness was m or less. This effect is due to the effect of sulfur at the crystal grain boundaries, and the strength of the grain boundaries is relatively reduced by the amount of the strengthening of the grain boundaries, which tends to increase the number of cracks penetrating the grains. It is considered that the workability is deteriorated as the value increases. Among the high silicon steel sheets having the chemical components shown in Table 1, those having a grain boundary oxygen concentration of about 5 at%, a grain boundary carbon concentration of about 1 at% and a grain boundary sulfur concentration of about 0.05 at% have a crystal grain size. The relationship between the average grain size as seen from the plate surface and the three-point bending property was investigated by varying the value. The result is shown in FIG. According to this, the average crystal grain size is 2.0 m
It can be seen that workability is improved by setting the thickness to m or less.

The high silicon steel sheets used in the various experiments described above have extremely good crystal grain growth properties by heat treatment, are likely to form coarse grains, and have a so-called bamboo structure in which crystal grains penetrate in the plate thickness direction. However, as described above, the crystal grain size of the steel sheet is preferably 2.0 mm or less from the viewpoint of workability, and it is necessary to control the heat treatment conditions so that the crystal grains do not become too large. We have
It has been found that when the crystal structure of the high silicon steel sheet has a bamboo structure, the actual crystal grain growth stops at a grain size of 3 to 4 times the plate thickness of the steel sheet. Therefore, in order to keep the crystal grain size at 2.0 mm or less, the plate thickness may be set at 0.5 mm or less, and in this case, it is not necessary to consider heat treatment. For these reasons, the plate thickness of the steel plate is preferably 0.5 mm or less.

The effect of the present invention is obtained regardless of the crystal orientation distribution of the silicon steel sheet, and therefore the present invention does not matter whether it is a grain-oriented silicon steel sheet or a non-oriented silicon steel sheet. . In addition, although a film for the purpose of insulation is usually formed on the surface of the electromagnetic steel sheet, the effect of the present invention is not affected by the presence or absence of the film. Further, in the present invention, there is no particular restriction on the method of obtaining a thin plate, and the present invention can be applied to a high silicon steel plate manufactured by an appropriate method such as the above-described special rolling method or siliconizing method.

[0024]

【Example】

[Example 1] Plate thickness of 0.1 m having the composition shown in Table 2
m high silicon steel sheet, 5 torr to 1 × (1/10
⁵ ) In an atmosphere of vacuum degree with different torr range,
Heat treatment (final annealing) was performed at 1200 ° C. for 15 minutes. At this time, the laboratory temperature was 27 ° C. and the humidity was 80%. The sample thus obtained was subjected to the three-point bending test shown in FIG. 2, and the stroke distance at which the sample could be pushed in without cracking was measured. In addition, bring the remaining material of each sample into the Auger electron spectrometer,
It was broken in a vacuum of 8 × (1/10 ¹⁰ ) torr, and the broken surface was observed to analyze the composition at the grain boundaries. Based on this compositional analysis, the oxygen concentration in the grain boundary was 3 to 5
t%, grain boundary carbon concentration of about 0.3 at% and average crystal grain size of about 0.2 mm were selected, and the influence of the grain boundary sulfur concentration on the three-point bending amount was examined for these samples. The result is shown in FIG. 7. According to this, when the sulfur concentration in the crystal grain boundary is decreased, the three-point bending amount is obviously improved, and it is understood that the workability is better when the sulfur concentration in the crystal grain boundary is lower.

Example 2 With respect to high silicon steel sheets having various thicknesses and having the composition shown in Table 3, 1 × (1/10 ⁴ )
800 to 1300 in an atmosphere with a vacuum degree of torr
Final annealing was performed for 15 minutes at different annealing temperatures in the range of ° C to prepare samples having various plate thicknesses and average crystal grain sizes. A three-point bending test was performed on the samples thus obtained, and the residual material of each sample was brought into an Auger electron spectroscope to measure the oxygen concentration, carbon concentration, and sulfur concentration of grain boundaries. As a result of Auger electron spectroscopy measurement, the grain boundary oxygen concentration was 8 ± 2 at%, the grain boundary carbon concentration was 0.8 to 2 at%, and the grain boundary sulfur concentration was 0.05 to 0.10.
It was in the range of at%. Table 4 shows the average crystal grain size of each sample and the result of the three-point bending test. According to this, it can be seen that the bending property is significantly deteriorated when the average crystal grain size exceeds 2.0 mm. Further, those having a plate thickness of more than 0.5 mm are inferior in bending property even if the average crystal grain size is 2.0 mm or less.

Example 3 A silicon steel sheet having a chemical composition shown in Table 5 and a thickness of 0.3 mm was prepared and subjected to a siliconizing treatment-diffusion treatment (Si diffusion infiltration treatment) at 1200 ° C.
The siliconizing treatment is performed using silicon tetrachloride (SiCl ₄ ) mixed with high-purity nitrogen gas (dew point −70 ° C.) as a carrier gas.
Two atmosphere gases were used: an atmosphere gas and a silicon tetrachloride (SiCl ₄ ) atmosphere gas in which nitrogen gas (dew point −30 ° C.) was mixed as a carrier gas. A three-point bending test was performed on these samples, and the oxygen concentration, carbon concentration, and sulfur concentration at the grain boundaries were measured from the remaining material by Auger electron spectroscopy. Based on this compositional analysis, those having a grain boundary oxygen concentration of about 10 at%, a grain boundary carbon concentration of about 0.7 at%, and an average crystal grain size of about 0.80 mm were selected from the samples. The correlation between sulfur concentration and three-point bending amount was investigated. The result is shown in FIG. According to this, it can be seen that, even in the high-silicon steel sheet obtained by the Si diffusion and infiltration treatment, the regulation of the sulfur concentration in the crystal grain boundaries is effective in improving the workability of the steel sheet.

Example 4 A steel plate having a composition of the components shown in Table 6 and a plate thickness of 0.35 mm was prepared by a rolling method, and the dew point was-.
10 ℃ to -70 ℃, H ₂ S concentration 0 to 0.1 vol
The heat treatment was performed at 1200 ° C. for 15 minutes in the nitrogen atmosphere changed in%. The three-point bending test shown in Fig. 2 was performed on these samples, and the oxygen concentration and the sulfur concentration of the crystal grain boundaries were measured from the residual material by Auger electron spectroscopy to determine the effect of the grain boundary oxygen on the three-point bending amount. The effect of concentration and intergranular sulfur concentration was investigated. The result is shown in FIG. According to this
When the grain boundary oxygen concentration is 30 at% or less, the correlation between the grain boundary sulfur concentration and the three-point bendability is recognized, but the grain boundary oxygen concentration is 30 at%.
It is found that when the content exceeds 0.1%, there is almost no change in the three-point bendability even when the grain boundary sulfur concentration is reduced to 0.2 at% or less.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

[0031]

[Table 4]

[0032]

[Table 5]

[0033]

[Table 6]

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the degree of vacuum in the final annealing atmosphere and the three-point bending property of a steel sheet obtained from a test conducted by the inventors of the present invention.

FIG. 2 is an explanatory diagram showing a three-point bending test method for evaluating workability of a steel sheet.

FIG. 3 is a graph showing the relationship between the grain boundary sulfur concentration and the three-point bending property for a high silicon steel sheet having a grain boundary oxygen concentration of 3 to 5 at%.

FIG. 4 is a graph showing the relationship between the grain boundary sulfur concentration and the tensile elongation of the steel sheets for high silicon steel sheets having substantially the same grain boundary oxygen concentration.

FIG. 5 is a graph showing the relationship between the grain boundary sulfur concentration and the grain boundary oxygen concentration and the three-point bending property of the steel sheet.

FIG. 6 is an average crystal grain size as seen from the plate surface and three-point bending for a high silicon steel sheet having a grain boundary oxygen concentration of about 5 at%, a grain boundary carbon concentration of about 1 at%, and a grain boundary sulfur concentration of about 0.05 at%. Graph showing the relationship with characteristics

FIG. 7 is a graph showing the relationship between the grain boundary sulfur concentration and the three-point bending property of the high silicon steel sheet of Example 1

FIG. 8 is a graph showing the relationship between the grain boundary sulfur concentration and the three-point bending property of the steel sheet for the high silicon steel sheet of Example 3

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsushi Kasai 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Kazuhisa Okada 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Date Main Steel Pipe Co., Ltd.

Claims (5)

[Claims] 1. An Si concentration of 4 to 10 wt%, an O concentration at a crystal grain boundary (O concentration in an element segregated at the crystal grain boundary) is 30 at% or less, and an S concentration at the crystal grain boundary (at the crystal grain boundary). A high silicon magnetic steel sheet having excellent workability, in which the S concentration in the segregating element) is 0.2 at% or less. 2. C: 0.01 wt% or less, Si: 4-1
0 wt%, Mn: 0.5 wt% or less, P: 0.01 wt
% Or less, S: 0.01 wt% or less, Sol. Al: 0.
2 wt% or less, N: 0.01 wt% or less, O: 0.02
wt% or less, the balance being Fe and unavoidable impurities, and the O concentration in the crystal grain boundaries (O in the elements segregated at the crystal grain boundaries
A high-silicon electrical steel sheet having excellent workability, in which the concentration) is 30 at% or less, and the S concentration in the crystal grain boundary (S concentration in the element segregated in the crystal grain boundary) is 0.2 at% or less. 3. Si + Al: containing 4 to 10 wt%,
O concentration in the crystal grain boundary (O concentration in the element segregated in the crystal grain boundary) is 30 at% or less, S concentration in the crystal grain boundary (S concentration in the element segregated in the crystal grain boundary) is 0.2 at%
The following are high-silicon electrical steel sheets with excellent workability. 4. C: 0.01 wt% or less, Si + Al:
4 to 10 wt%, Mn: 0.5 wt% or less, P: 0.0
1 wt% or less, S: 0.01 wt% or less, N: 0.01
wt% or less, O: 0.02 wt% or less, balance Fe and unavoidable impurities, O concentration in crystal grain boundaries (O concentration in elements segregated in crystal grain boundaries) is 30 at% or less, S concentration in crystal grain boundaries (S in elements segregated at the grain boundaries
A high silicon electrical steel sheet having a workability of 0.2 at% or less. 5. The workability according to claim 1, claim 2, claim 3 or claim 4, wherein the plate thickness is 0.5 mm or less and the average crystal grain size when viewed from the plate surface is 2.0 mm or less. Excellent high silicon electrical steel sheet.