JP2528749B2 - High silicon steel plate with uniform and excellent magnetic properties - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high silicon steel sheet manufactured by a diffusion and infiltration method of Si.

[0002]

2. Description of the Related Art A high silicon steel plate is used as an electromagnetic steel plate. It is known that this type of steel sheet exhibits the most excellent magnetic properties such that the iron loss is reduced as the Si content increases, the magnetostriction becomes 0 near Si 6.5 wt%, and the maximum magnetic permeability becomes peak. Has been. However, if the amount of Si is 4 wt% or more, the workability is remarkably deteriorated, and it is difficult to manufacture it by rolling or the like. Therefore, there has been proposed a method of producing a high-silicon steel sheet by using a silicon steel sheet of 4 wt% or less that can be thinned by rolling and infiltrating Si into this by a diffusion infiltration method to enrich Si. Regarding such a diffusion and penetration method, for example, Japanese Patent Publication No. 45-21181 and Japanese Patent Publication No. 62-227078.
No. etc. have been proposed.

[0003]

By the way, SiC
When Si compounds such as l ₄ , SiH ₄ , and SiHCl ₃ are used as raw materials and Si is diffused and permeated from the surface layer of the steel sheet by the diffusion and permeation method, the diffusion rate of Si atoms is about twice that of Fe atoms. There is a problem that a quendal void is generated in a portion having a steep concentration gradient. Further, although the electromagnetic steel sheet usually contains Al, when such a material is subjected to a siliconizing treatment, Al is concentrated in the vicinity of the voids even if the Al content is about 40 ppm, and , A
There is a problem that l is combined with oxygen and nitrogen in the steel sheet to cause segregation of Al ₂ O ₃ and AlN. Then, when Al concentration, segregation and remarkable voids are generated in the siliconizing treatment step as described above, these remain after the diffusion treatment and remarkably deteriorate the magnetic properties of the steel sheet.

However, in the conventional manufacturing method as described above, only the siliconizing conditions are mainly examined, and segregation of impurity elements such as Al, which adversely affects the magnetic properties, and the formation of kendal voids. It is hard to say that the behavior has been thoroughly studied. That is, Japanese Patent Publication No.
In No. 181, in order to suppress the generation of voids, SiCl ₄
Concentration of 1 vol% or less in Ar atmosphere, and N
₂ It is specified that it should be 0.7 vol% or less in the atmosphere. However, the magnetic property is particularly excellent at 6.0.
From the viewpoint of continuously producing a silicon steel sheet of not less than wt%, the diffusion and infiltration treatment time becomes too long under such a low concentration condition of the reaction gas, and it is difficult to realize the continuous production of the silicon steel sheet. . Further, according to the experiments by the present inventors, even if the reactive gas is made to have a higher concentration than the above and the siliconizing treatment is performed, voids and segregation of Al do not occur, and high silicon having very excellent magnetic characteristics is obtained. It has been confirmed that a steel sheet may be obtained.

Japanese Patent Publication No. 62-227078, which was previously proposed by the present applicant, is a method capable of producing a high-quality high-silicon steel sheet in a short time by carrying out a diffusion and permeation treatment of Si in a continuous line. It is about. In this manufacturing method, voids generated in the siliconizing process are eliminated in the soaking diffusion process in the next step,
There was no particular problem in terms of magnetic properties. However, in a subsequent study by the present inventors, remarkable voids may be generated depending on the siliconizing treatment conditions, and particularly when the pretreatment of the steel sheet such as pickling is insufficient or in the furnace. It has been found that, even if the steel sheet is oxidized even in the slightest amount, the voids generated in the Si infiltration treatment process tend to remain even after the soaking diffusion treatment. In addition, under the siliconizing condition where voids are generated,
It was also found that Al concentrates at a certain depth of the steel sheet and causes segregation, which deteriorates the magnetic properties of the steel sheet.

[0006]

In view of the above problems, the inventors of the present invention have considered that with respect to a steel sheet manufactured by a siliconizing treatment, the voids remaining in the steel sheet, the concentration of Al and the magnetic properties are As a result, the inventors have found a high silicon steel sheet that is homogeneous and has excellent magnetic properties. That is, the structure of the present invention is as follows.

(1) In a high-silicon steel sheet produced by subjecting a silicon steel sheet containing Si: 4.0 wt% or less to a material steel sheet and subjecting this to a siliconizing treatment, voids remaining in the section in the sheet thickness direction of the steel sheet Number (however, if there are voids larger than 1 μm, the number is divided into 1 μm or less and counted)
Is 20 or less per 1 mm in the width direction of the steel sheet, which is a high silicon steel sheet having uniform and excellent magnetic properties.

(2) In a high silicon steel plate produced by subjecting a silicon steel plate containing Si: 4.0 wt% or less to a material steel plate and subjecting this to a siliconizing treatment, the average Si amount in the plate thickness direction is 5.8 to 7. .2 wt%, and the number of voids remaining in the cross section of the steel sheet in the plate thickness direction (however, when there are voids of more than 1 μm, the number of voids divided into 1 μm or less and counted) is 10 per 1 mm in the steel plate width direction. A high silicon steel sheet having a uniform and excellent magnetic property, characterized by being less than or equal to the number of pieces.

(3) In the high silicon steel sheet according to the above (1) or (2), Sol. Al: 0.1 wt% or less, and a high silicon steel plate having uniform and excellent magnetic properties, characterized by Al scattered in the steel plate.

[0010]

The details of the present invention will be described below. When residual voids or Al is concentrated or segregated in the steel sheet, it becomes a factor that obstructs the passage of magnetic flux when the steel sheet is magnetized, which deteriorates the magnetic properties of the steel sheet. Therefore, the present invention clarifies the effects of residual voids, Al concentration, and segregation on the magnetic properties, and provides a high silicon steel sheet having excellent magnetic properties.

The present inventors firstly examined Si: 3w in order to verify the relationship between the siliconizing treatment conditions and the occurrence of voids and Al concentration.
Reaction temperature: 1150
A siliconizing treatment test was performed under conditions of ° C and atmosphere: Ar or N ₂ while changing the concentration of the reaction gas SiCl ₄ gas and the siliconizing treatment time. In this test, the surface Si
When the content was always less than 14.3 wt% during the siliconizing treatment, and when the Si content of the surface layer was 14.3 wt%, Fe
The occurrence of the concentration of voids and Al was investigated when the ₃ Si layer was formed.

As a result, if the Si content of the surface layer is always less than 14.3 wt% during the siliconizing treatment, no void or Al concentration or segregation occurs regardless of the Si concentration gradient in the plate thickness direction. I understood. On the other hand, when the Si content of the surface layer reaches 14.3 wt% and the Fe ₃ Si layer starts to be formed, from the Fe ₃ Si layer to the Si concentration gradient portion,
It was found that voids and Al thickening occurred. In such a steel sheet, voids were slightly reduced after the soaking and diffusion treatment, but did not completely disappear, and Al concentration and segregation were hardly changed.

Based on the results of such a test, by changing the Si concentration in the surface layer of the steel sheet during the siliconizing treatment and the Si concentration gradient from the surface layer to the inside of the steel sheet, a high silicon content with different residual void numbers after the soaking diffusion treatment is obtained. A steel plate was created. First, a Si: 3 wt% material steel plate was subjected to a siliconizing treatment to prepare a plurality of high silicon steel plates having an average Si amount in the plate thickness direction of 4 to 7.2 wt% and different residual void numbers, and examined their magnetic properties. . The number of residual voids was obtained by counting the number of voids existing in the plate cross section per 1 mm in the width direction of the steel sheet, and when the voids of more than 1 μm were present, the number was divided into 1 μm or less and counted.

As a result, as shown in FIG. 10, in the steel sheet in which the average Si amount in the sheet thickness direction after the siliconizing treatment is 6 wt% or more,
When the number of residual voids exceeds 20, the maximum magnetic permeability deteriorates by about 20% or more as compared with the material having the number of residual voids of 1 or less. Further, even a steel sheet having an average Si amount in the sheet thickness direction of less than 6 wt% deteriorates the characteristics by about 10% or more. From this, in order to obtain a high silicon steel sheet having excellent magnetic properties, the number of residual voids in the steel sheet cross section must be 20 or less per 1 mm in the steel sheet width direction. In particular, with respect to a steel sheet having an average Si amount in the plate thickness direction of 5.8 to 7.2 wt%, the characteristics are significantly deteriorated with an increase in residual voids. It is preferable that the number is 10 or less per 1 mm in the width direction of the steel sheet.

Next, in order to investigate the influence of Al concentration and segregation, Sol. A high-silicon steel sheet in which materials having different Al concentrations are subjected to siliconizing treatment, the average Si amount in the sheet thickness direction is 6.4 to 6.6 wt%, and the number of residual voids in the steel sheet cross section is 5 or less per 1 mm in the sheet width direction. It was created. For such steel sheets,
As a result of examining the state of occurrence of Al concentration and segregation, it was roughly divided into Sol. Al concentration is 100 ppm or less, 0.
In each case of 1% or less and over 0.1%, differences in Al concentration and segregation were observed.

That is, according to the IMA image photographs of these steel sheets, the sol. Al concentration is 100ppm
In the following, Al was scattered in the steel sheet sparsely and evenly, and Al concentration and segregation were not observed at all. On the other hand, Sol. In a material having an Al concentration of 0.1%, Al begins to be scattered on a straight line, and a concentration tendency is recognized. However,
It has not reached extreme concentration or segregation. On the other hand, So
l. In a material having an Al concentration of 0.3%, Al is concentrated in a straight line, and the concentrated and segregated portions occupy a considerable area in the steel sheet.

Based on this test result, A shown in FIG.
In order to obtain a high silicon steel sheet having excellent magnetic characteristics, from the relationship between the concentration and segregation of l and the magnetic characteristics, Al must have a degree of homogeneity scattered in the steel sheet. Al
The concentration must be less than 0.1%. In particular, Al
In order to obtain a high-silicon steel sheet having a more uniform and excellent magnetic property, such that is not reflected in the ion image, or is scattered and averaged in the steel sheet, Sol. Al concentration is 1
It is necessary to set it to 00 ppm or less.

In the conventional silicon steel sheet, a method of replacing a part of Si with Al is used by utilizing the effect of increasing the electric resistance of Al and the effect of improving the spreadability. Average Si content easily 6.0-7.0w
Since it can be set to t%, it is not necessary to add Al for improving the magnetism. On the contrary, from the viewpoint described above, Sol. Al: 0.
It is preferably 1 wt% or less, and more preferably 100 ppm or less.

In the present invention, the impurity components other than Si and Al in the raw steel sheet are not particularly limited, but are preferably defined as follows in order to obtain excellent magnetic properties.

First, the non-metallic element will be described. C: C lowers the initial magnetic permeability and the maximum magnetic permeability, increases Hc, and increases iron loss. It is known that this effect becomes remarkable when it exceeds 0.01 wt%, as shown in FIG. 15. Therefore, it is preferable that C be 0.01 wt% or less. However, in order to improve the crystal orientation, it is possible to contain more than 0.01 wt% of C in the steelmaking stage and roll it. In this case, decarburization annealing is performed to prevent aging and property deterioration. However, it is preferable that C is 0.01 wt% or less. That is, the C concentration may be adjusted at the smelting stage or by performing decarburizing annealing.

O: O is known as an element which enhances iron loss and, when present as colloidal fine particles such as SiO ₂ , significantly deteriorates magnetic properties. O is C
The magnetic characteristics are changed depending on the degree of coexistence with. In particular, as shown in FIG. 16, when the O content and the C content are almost the same, it is also known that the iron loss value becomes the minimum, and the O content is the same as the appropriate range of the C content. Is 0.
It is preferable that the content be 01 wt% or less.

N and S: Since both cause aging, it is preferable to reduce them as much as possible.
It is preferable that the content be 01 wt% or less. P: P has the effect of reducing magnetic deterioration due to oxygen and reducing iron loss. However, if added in a large amount, there is a problem that workability during hot working is deteriorated.
It is preferably set to 2 wt%. H: Since H makes the steel sheet extremely brittle, aggressive inclusion such as H under high pressure should be avoided (usually p
pm level). As described above, it is preferable to minimize C, O, N, S, etc., and optimize the ratio of C and O for the nonmetallic elements.

Explaining the metal element, Mn: M in consideration of the improvement of the ductility at the time of hot rolling and the effect of improving the magnetism in the desulfurization action and the ordered-disordered transformation.
n is preferably added in a range of 0.5 wt% or less. Ca: If Ca is contained in a large amount, the magnetic permeability is reduced. Therefore, the content is preferably not more than 0.3 wt%.

V: By adding a slight amount of V, Hc
Are known to be improved. That is, V is 0.
Addition of about 05 wt% promotes the development of crystal grains and improves magnetism. Therefore, V is 0.1 wt
% Can be added up to the upper limit. By adding about 0.05 wt% of Ti, the same effect as V can be expected, so that 0.1 wt% can be added as an upper limit. Be, As: A slight magnetic property improving effect can be expected, and 0.1 wt% of each can be added as an upper limit.

Cu: Up to about 0.7 wt%, the magnetism is not significantly deteriorated, but if it exceeds 0.7 wt%, iron loss increases. Therefore, Cu is 0.7 wt.
% Or less, preferably 0.1 wt% or less. Cr: tends to increase iron loss, and is preferably set to 0.03 wt% or less. Ni: To significantly deteriorate magnetic properties, it is preferable to reduce the Ni as much as possible, and it is preferable to set the content to 0.01 wt% or less.

[0026]

【Example】

[Example 1] Si: 3 wt%, Sol. Al: 110p
pm, a reaction gas concentration (SiCl ₄ concentration of 1 to 30 vol% was applied to a silicon steel plate cold-rolled to a thickness of 0.35 mm.
Was changed within the range of 1) and the treatment time was changed to 1150 ° C.
Silica-soaking and diffusion treatment was carried out. The average Si amount in the plate thickness direction of the steel sheet after the siliconizing-soaking diffusion process is 4 wt%, 5 wt
%, 5.8-6 wt%, 6.4-6.6 wt%, 7-
It was 5 levels of 7.2 wt%. Atmosphere gas conditions are Ar
And it was performed at two levels of N _2, since almost the same result irrespective of the ambient gas conditions are obtained, the following shows a representative result of Ar. In addition, Table 1 shows the components of the material steel sheet subjected to the siliconizing treatment.

In FIGS. 1 and 2, the surface layer has a Si concentration of about 1
SEM of steel sheet on which Fe ₃ Si layer of 4.3 wt% is formed
An enlarged photograph of the cross section (Fig. 1: full cross section of steel plate thickness direction, Fig. 2: cross section of surface layer) is shown in Figs.
The MA ion imaging photograph (FIG. 3: Al, FIG. 4: Si) is shown. In addition, the surface layer during the siliconizing treatment is always 1 in FIGS.
An enlarged SEM cross-section photograph of the steel plate that was less than 4.3 wt% (Fig. 5: full cross-section in the steel plate thickness direction, Fig. 6: cross-section of surface layer)
Further, FIGS. 7 and 8 show IMA ion imaging photographs (FIG. 7: Al, FIG. 8: Si) of the steel sheet. Note that the shooting range of the photographs shown in FIGS. 3, 4, 7, and 8 is shown in FIG.

As shown in these photographs, Fe is formed on the surface layer.
_In the steel sheet on which the ₃ Si layer is formed (Figs. 1 to 4), Fe ₃ S
Voids were remarkably generated in the Si concentration gradient portion near the boundary with the i layer, and Al was intensely concentrated there. On the other hand, in the steel sheet in which the surface layer was always less than 14.3 wt% during the siliconizing treatment (Figs. 5 to 8), no remarkable void was generated, and Al was not concentrated and scattered in the steel sheet. Was. The residual voids were evaluated by counting the voids within the length range of 1 mm in the steel plate width direction from the cross-sectional photograph. Most of the sizes were from submicron to 2-3 microns, and when they were connected, they were counted by dividing them into units of 1 micron.

FIG. 10 shows the relationship between the number of residual voids and the maximum magnetic permeability of the steel sheet. According to this, in the steel sheet having an Si amount of 6 wt% or more, the residual void number is 20 per 1 mm in the steel sheet width direction.
When the number exceeds 5, the maximum permeability is deteriorated by 20% or more as compared with the material in which the number of residual voids is 1 or less. Also, Si is 6
Even with steel sheets of less than wt%, the characteristics are deteriorated by about 10% or more. From this result, in order to obtain a high silicon steel sheet having excellent magnetic properties, the number of residual voids in the cross section in the steel sheet thickness direction must be 20 or less per 1 mm in the steel sheet width direction.
In particular, in the case of a product having a Si content of 5.8 to 7.2 wt%, the characteristics are largely deteriorated with an increase in residual voids. Therefore, in order to obtain more excellent magnetic characteristics, the residual voids number per 1 mm in the width direction of the steel sheet 10 or less, more preferably 5
Should be less than or equal to.

[Embodiment 2] Sol. A
In order to investigate the effect of the concentration of Sol.
3% Si silicon steel plate with different Al concentration (plate thickness 0.35 m
m) was used as a material steel plate, and this was subjected to a siliconizing-soaking diffusion process to manufacture a high silicon steel plate having an average Si amount in the plate thickness direction of 6.4 to 6.65 wt%.

FIG. 11 shows Sol. The relationship between the Al concentration and the maximum magnetic permeability of the steel sheet after the siliconizing-soaking diffusion process is shown. According to this, Sol. A material having a maximum magnetic permeability of 30,000 or more has been obtained in a material having an Al concentration of 0.1 wt% or less. Al concentration is 100ppm
In the following, more excellent magnetic characteristics are obtained. FIG.
2 to 14 show Sol. Al concentration 60ppm (Fig. 1
2), 0.1 wt% (FIG. 13), 0.3 wt% (FIG. 1)
IMA showing the state of Al concentration and segregation in the steel plate cross section after the siliconizing-soaking diffusion process for each material of 4).
It is an ion imaging photograph.

According to this, Sol. Al concentration is 60p
In the case of the pm material, Al after the siliconizing treatment-soaking and diffusion treatment is scattered at most in the steel plate cross section (or not visible in the IMA ion photograph). On the other hand, Sol. In a material with an Al concentration of 0.1 wt%, Al is a Si concentration gradient portion (especially Fe ₃
A large number of them are scattered on a straight line in the vicinity of the boundary with the Si layer) and start to show a concentration tendency. Furthermore, Sol. With a material having an Al concentration of 0.3 wt%, the concentration of Al becomes severe, and the concentration increases in the connected state. The material Sol. Al
Regardless of the concentration, the precipitates present in the Al concentrated part are
l ₂ O ₃ .

From the above results, excellent magnetic properties can be obtained as long as Al is scattered in the cross section of the steel plate in the IMA ion photograph, and for that purpose, the Sol. The Al concentration must be 0.1 wt% or less, and in order to obtain more excellent magnetic properties, the material Sol. Al concentration of 10
It was confirmed that it is preferable to set the content to 0 ppm or less.

[0034]

As described above, the steel sheet of the present invention has uniform and excellent magnetic properties by controlling the number of residual voids in the steel sheet cross section and further the Al concentration.

[Brief description of drawings]

FIG. 1 is an enlarged SEM cross-sectional photograph showing the metallographic structure of the entire cross section in the plate thickness direction of a steel sheet having a Fe ₃ Si layer formed on its surface.

FIG. 2 is an enlarged SEM cross-sectional photograph showing the metal structure of the cross section of the surface layer of the steel sheet having the Fe ₃ Si layer formed on the surface layer.

FIG. 3 is an IMA ion imaging photograph of Al in a surface layer cross section of a steel sheet having a Fe ₃ Si layer formed on the surface layer.

FIG. 4 is an IMA ion photograph of Si in a surface layer cross section of a steel sheet having a Fe ₃ Si layer formed on the surface layer.

FIG. 5 is an enlarged SEM cross-sectional photograph showing the metallographic structure of the entire cross section in the plate thickness direction of the steel sheet whose surface layer was always less than 14.3 wt% during the siliconizing treatment.

FIG. 6 is an enlarged SEM cross-sectional photograph showing the metallographic structure of the surface layer section of the steel sheet in which the surface layer was always less than 14.3 wt% during the siliconizing treatment.

FIG. 7 is an IMA ion imaging photograph of Al in the surface layer cross section of the steel sheet in which the surface layer was always less than 14.3 wt% during the siliconizing treatment.

FIG. 8 is an IMA ion image photograph of Si in the surface layer cross section of the steel plate in which the surface layer was always less than 14.3 wt% during the siliconizing treatment.

9 is an explanatory diagram showing a shooting range of the photographs shown in FIGS. 3, 4, 7, and 8. FIG.

FIG. 10 is a graph showing the relationship between the number of residual voids and the maximum magnetic permeability after the siliconizing treatment-soaking diffusion treatment.

FIG. 11: Sol. The graph which shows the relationship between the amount of Al and the maximum magnetic permeability after a siliconizing process-soaking diffusion process.

FIG. 12: Sol. An IMA ion image photograph showing the concentration and segregation of Al in the steel plate cross section after the silicon immersion-diffusion treatment of a material having an Al concentration of 60 ppm.

FIG. 13: Sol. IMA ion image photograph showing Al enrichment and segregation situation in the steel plate cross section after the silicon immersion-diffusion treatment of a material having an Al concentration of 0.1 wt%.

FIG. 14: Sol. IMA ion photograph showing the concentration and segregation of Al in the steel plate cross section after the silicon-diffusion treatment of the material having an Al concentration of 0.3 wt%.

FIG. 15 is a graph showing the effect of the content of impurity elements on iron loss.

FIG. 16 is a graph showing the effect of the content ratio of carbon and oxygen on iron loss.

[Table 1]

Claims (4)

(57) [Claims] 1. A high silicon steel sheet produced by subjecting a silicon steel sheet containing Si: 4.0 wt% or less to a material steel sheet and subjecting this to a siliconizing treatment, the number of voids remaining in a section of the steel sheet in the plate thickness direction. (However, if there are voids of more than 1 μm, the number of the voids divided into 1 μm or less and counted) is 20 or less per 1 mm in the width direction of the steel sheet. Silicon steel plate. 2. The Sol. Al: 0.1 wt% or less, and Al is scattered in the steel sheet. The high silicon steel sheet having homogeneous and excellent magnetic characteristics according to claim 1. 3. A high silicon steel sheet produced by subjecting a silicon steel sheet containing Si: 4.0 wt% or less to a material steel sheet and subjecting this to a siliconizing treatment, the average Si amount in the sheet thickness direction is 5.8.
Is about 7.2 wt%, and the number of voids remaining in the cross section in the plate thickness direction of the steel sheet (provided that there are voids larger than 1 μm,
A high silicon steel plate having a uniform and excellent magnetic property, characterized in that the number obtained by dividing this into 1 μm or less) is 10 or less per 1 mm in the width direction of the steel plate. 4. Sol. Al: 0.1 wt% or less, and Al is scattered in the steel sheet. The high silicon steel sheet having homogeneous and excellent magnetic properties according to claim 3.