JPS62227033A - Manufacture of high silicon steel strip in continuous line - Google Patents

Abstract

PURPOSE:To continuously manufacture high silicon steel sheet as superior electrical sheet, by permeating Si to steel sheet surface layer by chemical gas phase vapor depositing method in nonoxidizing atmospheric gas contg. SiCl4, successively applying Si diffusion treatment to obtain the structure in which Si content is gradually decreased to center part from surface layer. CONSTITUTION:Relatively low Si steel sheet contg. about 3% Si is manufactured by hot and cold rollings, then the sheet is heated to 1,023-1,200 deg.C in atmosphere of nonoxidizing gas such as Ar, H2, N2 contg. 5-35% SiCl4 in mol fraction to form Fe3Si layer contg. 14.5% Si by chemical gas phase vapor depositing method on silicon steel sheet. This is heated in nonoxidizing atmospheric gas to diffuse Si in surface layer while gradually decreasing it in center direction resulting in 6.5% Si at surface layer part and about 3% Si remaining as it is in material silicon steel sheet at center part, silicon steel sheet having ununiform compsn. in Si concn. in thickness direction is obtd. and insulating film of magnesium phosphate is formed on surface. Electrical sheet superior in high frequency electrical characteristic is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to chemical vapor deposition (hereinafter referred to as CO) in a continuous line.
The present invention relates to a method for manufacturing high-silicon steel strips by a method (referred to as VD).

[Conventional technology]

High-silicon steel sheets are used as electrical steel sheets. In this type of steel plate, the higher the Si content, the lower the loss, and Si:
It is known that at 6.5%, the magnetostriction becomes 0 and the maximum magnetic permeability reaches its peak, exhibiting excellent magnetic properties.

Conventionally, methods for producing high-silicon steel sheets include the rolling method, direct casting method, and silicon extrusion method. Of these, the rolling method can produce up to 81% Si content of about 4%, but Cold working is difficult because the workability deteriorates significantly. Further, although the direct casting method, so-called strip casting, does not have the problem of workability as the rolling method, it is still a technology under development and is prone to shape defects, making it particularly difficult to manufacture high-silicon steel sheets.

On the other hand, the silica method produces high-silicon steel sheets by melting low-silicon steel, rolling it into a thin plate, and then infiltrating Sl into the surface. A high-silicon steel plate can be obtained without causing any problems.

[Problem that the invention seeks to solve]

This infiltration method was proposed by Gokyu and Dokun, and was studied in detail by Mitani and Onishi, but all of the previously proposed methods required a long infiltration treatment time of 30 minutes or more, and also required CVD treatment. The subsequent diffusion heat treatment also
The fundamental problem is that it takes a relatively long time to uniformly diffuse the liquid into the base material, and it is virtually impossible to apply it to a continuous line. Furthermore, since the CVD treatment temperature is extremely high at around 1230℃, the shape of the thin steel sheet after penetration treatment is extremely poor.In addition, because the treatment temperature is too high, the edges may melt due to overheating, making it difficult to maintain stability in continuous lines. I can't expect it to pass.

In addition, high-silicon steel sheets with a Si content of 4.0- or more are brittle, and there is a problem in that they are susceptible to shaft breakage when the steel sheets are wound into coils after treatment.

The present invention has been made in order to improve the drawbacks of the prior art, and provides a method that can stably produce high-quality high-silicon steel strips in a short period of time on a continuous line using the silicon extrusion method. The purpose is to provide.

[Means to solve the problem]

Therefore, in the present invention, a steel strip is subjected to continuous silicon treatment at a temperature of 1023 to 1200°C by chemical vapor deposition in a non-oxidizing gas atmosphere containing 5 to 35 molar fraction of SiCl4. 1. Next, a diffusion treatment is performed to diffuse Si into the steel strip in a non-oxidizing gas atmosphere that does not contain SiC1°. Canceled while still high, S
Its basic feature is to obtain a steel strip in which the i concentration is non-uniform in the thickness direction.

Another basic feature of the present invention is that after the above-mentioned diffusion treatment and cooling, an insulating film coating and a baking treatment are performed.

The present invention will be explained in detail below.

In the present invention, the composition of the steel strip (starting thin steel strip) serving as the base material is not particularly limited, but is preferably determined as follows in order to obtain excellent magnetic properties.

■3 to 6.5% 5t-F6 alloy C: 0.01% or less, 5ilo to 4.0%, Mn:
It is desirable that the content of other avoidable impurities be as low as possible.

■For Sendust alloy C: 0.01 or less, Si: 4% or less, At: 3 to 8, Ni: 4% or less, Mn: 2% or less, Cr,
It is desirable that the content of elements that increase corrosion resistance, such as Ti, be 5% or less, and that the content of other unavoidable impurities be as low as possible.

The steel strip is not limited to one obtained by hot rolling-cold rolling, but may be one obtained by direct casting or rapid solidification.

Note that the thickness of the steel strip is reduced by CVD treatment, and therefore it is necessary to use a steel strip with a thickness equal to the thickness of the final product plus the reduced thickness.

The present invention provides such a steel strip with a silicon-etched treatment by the CVD method.
A high-silicon steel strip is obtained by performing a diffusion treatment.

Figure 1 shows a continuous ring treatment line for carrying out the method of the present invention, in which (1) is a heating furnace, (2) is a CVD treatment furnace, (
3) is a diffusion treatment furnace, and (4) is a cooling furnace.

The steel strip (S) is heated in a heating furnace (1) in a non-oxidizing manner to a CVD treatment temperature or close to it, and then led to a CVD treatment furnace (2) where it is heated with C in a non-oxidizing gas atmosphere containing S i C1.
8-silicon processing is performed using the VD method. Non-oxidizing gas containing SiClt means a neutral or reducing gas, and S
The carrier gas for iC2 is Ar, Nl, He.
, Hz, Ct (4, etc.) can be used. Among these carrier gases, when considering the treatment properties of exhaust gas, HSCH, etc. have the disadvantage of generating HCt, which requires treatment. Ar that does not cause any problems
, He, and N are preferable, and from the viewpoint of preventing nitridation of the material, Ay is especially preferable.
, )le are most preferred.

The main reaction on the W4 band surface during CVD treatment is 5Fe
+SiCl4→FeaS i +2 FeC1*↑. One Si atom is deposited on the steel strip surface to form a FeaSi layer, and two Fe atoms become FeC1, which is diffused from the steel strip surface in a gaseous state at a temperature higher than the boiling point of s FeC4, 1023°C. Therefore, the Si atomic weight is 28.086,
Since the Fe atomic weight is 55.847, the mass of the steel strip decreases, and the plate thickness also decreases accordingly. By the way, the base material is S13% steel strip, and Si6.5 is made by CVD treatment.
% steel strip, the mass decreases by 8.7 yen and the plate thickness decreases by approximately 7.1%. The CVD process takes too long in the conventional method.
This is thought to be due to insufficient consideration being given to the CVD processing conditions.According to the inventors' investigation, the following factors are necessary for speedy CVD processing. It turned out that.

■Optimization of SiClt4 concentration in atmospheric gas.

■Optimization of processing temperature.

■ Promotion of diffusion of S i Ct to the steel strip surface and diffusion of FeCl2 from the steel strip surface.

Therefore, in the present invention, the Si concentration in the atmospheric gas and the processing temperature in the CVD processing are specified.

First, 5i in a non-oxidizing gas atmosphere during CVD treatment.
The steel strip is continuously subjected to CVD treatment in such an atmosphere, with the concentration and mol fraction defined as 5 to 35 Cl.

Si expects that 5icz in the atmosphere is less than 5chi
No enrichment effect can be obtained, and for example, if the Si of the steel strip is 1.0
The treatment takes too much time, such as requiring more than 5 minutes for enrichment, making it difficult to implement a continuous process.

On the other hand, even if SiClt is contained in an amount exceeding 35%, the reaction at the interface becomes rate-limiting, and no further Si enrichment effect can be expected.

Further, in the CVD process, the higher the 5ick 8 degrees, the more likely a large void called a Kirkendahl void is generated. These voids are hardly seen when the SiCl413 degree is about 15%, but when it exceeds 15%, they begin to form. However, when the SiClt4 concentration is 35% or less, even if voids are generated, they can be almost completely eliminated by a diffusion process performed subsequent to the CVD process.

The time required for voids to disappear strongly depends on the diffusion treatment temperature, and by increasing the treatment temperature in accordance with the decrease in surface layer s11 degrees after the start of diffusion, voids can be eliminated in a short time. However, when SiCl479 degrees exceeds 35%, the diameter of the voids that occur becomes thick (becomes
In addition, adjacent voids coalesce and become even larger, and the voids remain even after long-time diffusion soaking treatment. On the other hand, 5tcz.

If the concentration is 35- or less, the voids will not be too large and can be eliminated by diffusion treatment.The CVD treatment temperature should be in the range of 1023 to 1200℃.
Since the CVD treatment reaction is a reaction on the steel strip surface, the treatment temperature is strictly the steel strip surface temperature.

The boiling point of FeC1°, which is a reaction product from the CVD process, is 1023°C, and below this temperature, FeC4 does not dissipate from the steel strip surface in a gaseous state, but adheres to the steel strip surface in a liquid state and inhibits the vapor deposition reaction. I end up. According to the results of basic experiments conducted by the inventors, this Fect! The enrichment rate of Si per unit time differs markedly across the boiling point of 1023
At temperatures below ℃, the deposition rate is low, making it difficult to apply to continuous processes. Therefore, the lower limit of the processing temperature is set to 1023°C.

On the other hand, the reason why the upper limit is specified as 1200°C is as follows. The melting point of Fe5Si is 1250°C, as is clear from the F, -Si phase diagram shown in Figure 3. However, according to experiments by the inventors, even when treated at about 1230°C, which is lower than 1250°C, the melting point of Fe5Si is 1250°C. The surface of the band is partially dissolved, and
The edge of the steel strip melts due to overheating. Like this 1
The reason why the steel strip melts even below 250℃ is because F on the surface of the steel strip is
It is presumed that this is because Si is deposited at a Si concentration of 14.5% or more equivalent to e3Si.

On the other hand, if the treatment temperature is 1200°C or less, no melting will be observed on the surface of the steel strip, and overheating of the edges will be reduced by setting the average temperature at the center of the steel strip to 1200°C.
It was experimentally confirmed that the temperature could be kept at about 0°C and only a small amount of dissolution was required. For the above reasons, CVD
The processing temperature is specified as 1023°C to 120°C.

The steel strip (S) subjected to the CVD treatment as described above is subsequently led to a diffusion furnace (3) and subjected to a diffusion treatment in a non-oxidizing gas atmosphere containing no Si C1.

In other words, immediately after the CVD treatment, the Si concentration near the surface of the steel strip is extremely high compared to the center, and by soaking the steel strip, the Si that is excessively concentrated on the surface is diffused into the steel strip. .

However, in the present invention, Si is not uniformly diffused into the steel strip by this diffusion heat treatment, and the surface layer Si concentration is higher than the 81 concentration at the center of the steel strip in the thickness direction. The steel strip has a non-uniform Si concentration in the thickness direction.

The present inventors investigated the relationship between the Sig degree distribution and magnetic properties of CVD-treated steel materials from the perspective of shortening the diffusion treatment time, and found that the magnetic properties of high-silicon steel materials depend on the grain size of the surface layer of the steel material. and Si concentration, and by adjusting the surface layer part to a predetermined particle size and Si concentration.

It has been found that sufficient magnetic properties can be obtained even if the Si concentration is not uniform in the thickness direction. It has also been found that this tendency is particularly remarkable in high frequency magnetic properties.

Therefore, in the present invention, the diffusion treatment following the CVD treatment is discontinued while the surface layer Si concentration is higher than the Si concentration at the center in the thickness direction of the steel strip, thereby obtaining a steel strip in which the Si concentration is non-uniform in the thickness direction. This is how it was done.

According to such a method, a steel strip with sufficiently secured magnetic properties can be obtained through short-time diffusion heat treatment. In addition, the steel strip obtained in this way has a low S in the center of the thickness.
Since the concentration is maintained at 1, the toughness is ensured and breakage can be appropriately prevented.

Figure 4 shows the change in the Si concentration distribution in the thickness direction of the steel strip according to the method of the present invention, and shows the case where a steel strip containing 3% Si is used as the base material and this is subjected to CVD treatment and diffusion treatment. There is. (A) shows the state immediately after CVD treatment, and S of Fe5Si phase i (Si: 14.5%) is on the surface of the steel strip.
i is deposited. In the present invention, such a steel strip (B)
A steel strip having a non-uniform Si concentration in the thickness direction is obtained. In the example shown in (B), the Si concentration in the surface layer is 6.
Diffusion heat treatment was performed until the Si concentration reached 5%, and the central part of the plate thickness was maintained at approximately 3%, which is the Si concentration of the base material.

The W4 obtained in this way can ensure excellent magnetic properties, especially high-frequency magnetic properties, by selecting the diffusion heat treatment temperature and treatment time and adjusting the surface layer to a suitable particle size and Si concentration. can.

This diffusion treatment must be performed in a non-oxidizing atmosphere to prevent the surface of the steel strip from being oxidized, and the higher the temperature, the shorter the treatment time.

The diffusion treatment may be performed at a constant temperature, but the Fe
As can be seen from the −8t phase diagram, as the diffusion progresses, the Si (1% degree) on the surface of the steel strip decreases and its melting point increases, so as the diffusion progresses, the temperature is gradually increased to the extent that the steel strip does not melt. By increasing the temperature (for example, increasing the temperature in multiple steps), the treatment can be carried out in a short time.

After such a diffusion treatment, the steel strip (S) is cooled in a cooling furnace (4) and then rolled up. steel? f (S) is usually
It is rolled up at room temperature to 300°C. In general, it is preferable to wind a steel strip with a high Si content (for example, 4.0% or more) and a relatively thick plate at a warm temperature.

In order to increase the CVD processing speed to the point where continuous processing of steel strips is possible, SiCl4 in the atmospheric gas is
It is necessary to optimize the concentration and processing temperature, but in addition to this, it is possible to further increase the CVD processing speed by promoting the diffusion of 5tcz to the steel strip surface and the dissipation of FeC4 from the steel strip surface. becomes possible.

Conventionally, it has been believed that large flow of reactive gas in CVD treatment causes voids to occur in the deposited layer and also reduces the purity of the deposited layer, so the idea has been that the flow of gas should be kept to the minimum necessary. However, in the research conducted by the present inventors, by suppressing the gas flow in this way, the reaction gas diffuses and moves to the base material interface.

The separation of reaction by-products and reaction by-products from the interface surface layer does not occur smoothly, which results in long processing times.Furthermore, gas flow is suppressed, causing a distribution in the reaction gas concentration within the CVD processing furnace. As a result, it was found that this resulted in non-uniformity in the thickness of the deposited film.

Based on these facts, we conducted further studies and found that SiCl4 can be applied to the surface of the steel strip by blowing atmospheric gas onto the treated material using a blowing nozzle in the CVD processing furnace, or by forcing the atmosphere to circulate using a fan, etc. It has been found that diffusion and dissipation of FeC4, a reaction product, from the surface of the steel strip are significantly promoted, and CVD processing can be performed at a high deposition rate while suppressing non-uniformity of the deposited film.

A method in which atmospheric gas is sprayed onto the surface of the steel strip using a spray nozzle is particularly effective for improving CVD processability.

Figure 5 shows the implementation status of this nozzle spraying method, in which a spray nozzle (5) is placed in the CVD treatment furnace (2) facing the steel strip (S), and sprays SiCl4 onto the surface of the steel strip. Atmospheric gas is sprayed. Figure 6 (a) and naka) are
This shows the spraying situation by the spray nozzle (5), which can spray at right angles to the steel strip surface as shown in B) or obliquely as shown in (C4).

Such a nozzle sprays a unit time of Si
The enrichment ratio increases in proportion to the increase in the flow velocity of gas colliding with the steel strip surface, but even if the flow velocity is increased excessively, the reaction rate at the interface becomes rate-determining, so no further Si enrichment effect can be expected. In general, a sufficient effect can be obtained with a flow rate of 5 Nm/sec or less.

Further, in the present invention, after the above-mentioned diffusion treatment and cooling, the steel strip can be continuously coated with an insulating film and then rolled up after the baking treatment.

Figure 2 shows the continuous processing line for this purpose.
) is a coating device, and (7) is a baking furnace.

Electrical steel sheets are usually used in a laminated state, and in this case, each of the laminated steel sheets needs to be insulated. For this reason, electrical steel sheets are coated with an insulating film.

A steel strip with a Si content of 4.0 min or more is a brittle material at room temperature and hardly undergoes plastic deformation. For this reason, if the insulating film coating is performed on a separate line such as a CVD processing line, there is a risk that the steel strip will break during unwinding or unwinding of the coil. Therefore, in the present invention, after the diffusion treatment and cooling, the steel strip (S) is coated with an insulating paint using a coating device (6).
The coating is then baked in a paint baking oven (7). As the insulating paint, an appropriate inorganic or organic type can be used. Examples of inorganic paints include magnesium phosphate,
Anhydrous chromium modified, silica sol, etc. are used, and as the organic paint, plastic resin etc. are used. The paint is applied to the steel strip (S) using a halo coater method, one-way spray method, etc.
In the case of inorganic paints, the baking process is carried out at approximately 800℃, and in the case of organic paints, it is baked at approximately 200 to 300℃. Heating methods such as heating, induction heating, radiant tube indirect heating, direct flame reduction heating, etc., are used alone or in combination with the vehicle.In addition, if one indirect heating blade method is used, before heating, electric cleaning etc. Treatment is performed. For example, the following heating method including pretreatment can be adopted.

■Pretreatment - [Preheating] - Electrical indirect heating (or induction heating) ■Pretreatment - [Preheating] - Radiant tube heating - Electrical indirect heating (or induction heating) ■ [Preheating] - Direct flame reduction heating -
Electrical indirect heating (or induction heating) ■Pretreatment - [Preheating] - Radiant tube indirect heating (ceramic radiant tube method) % formula % There are no particular limitations on the cooling method in the cooling furnace (4), such as gas jet cooling, mist cooling, etc. Various cooling methods such as cooling and radiation cooling can be used alone or in combination.

As mentioned above, the present invention is suitable for manufacturing steel strips with extremely high silicon content, such as 6.5% Si steel strips. There is an advantage that steel strips with a high silicon content of about 2 to 4% can be easily produced, which had a poor yield due to a large amount of Si.

〔Example〕

0 Example-1 Using a small CVD processing furnace = misery←exploding heat←, the influence of SI Ct4 temperature and CVD processing temperature on CVD processability was investigated. The results are shown in FIGS. 7 and 8.

In the figure, A is the atmosphere method, that is, CVD treatment without nozzle spraying, and B is the nozzle spraying method, that is, as shown in Figure 5, 0.5 nL of atmospheric debris was applied to the steel strip surface.
This shows the case where CVD treatment was performed while spraying at a flow rate of /3.

According to this, S i Ct, concentration 5 qb or more,
When the C'VD treatment temperature is 1023°C or higher, large Si
An enrichment effect has been obtained. In addition, even under the same conditions, the method of spraying atmospheric gas with a spray nozzle provides a much superior Si enrichment effect (CVD processability) compared to the method of simply passing the steel strip through the atmosphere. I understand.

Fig. 9 shows the relationship between the deposition time and the 81 concentration in the steel strip (base material Si quantity, evaporated Sl amount) for the atmosphere method A and nozzle spraying method B using a similar CVD processing furnace.Si: 3%, plate Thickness 0.5
- steel strip with SiCl4 @ 21 degrees, treatment temperature 1150℃
This study investigated the case of CVD treatment. In addition, it was sprayed with a nozzle. As can be seen from the figure, 6.5%S
While it takes 7 minutes in the atmosphere corporation to obtain the s1 deposition amount equivalent to i steel, the nozzle spraying method B was able to complete the process in 1.5 minutes.

Figure 10 shows the relationship between the collision gas flow velocity and the Si enrichment ratio of the steel strip (same as Figures 7 and 8) in the nozzle blowing method. Up to a certain level, the relationship is proportional to the collision gas flow velocity. Therefore, the Si enrichment ratio of the steel strip is increasing.

0 Example-2 By the continuous process shown in Fig. 1, the same amount of Si
Steel strips were produced with different diffusion treatment times depending on the amount of vapor deposition, and the degree of Si diffusion and magnetic properties of these steel strips were investigated. Specifically, steel containing 813 Ti was used with a thickness of 0.35 m and a width of 900 laps. Use obi as material, line speed 5~s o m
The passage time of the diffusion furnace is changed by changing the pm range, and the CVD treatment (CVD treatment temperature 1050-1150
°C)-diffusion treatment was performed. In addition, in order to prevent the Si deposition amount from changing due to differences in line speed, the SiC/4 concentration in the CVDg surrounding gas (10 to 30 tL) and the amount of atmospheric gas sprayed from the gas spray nozzle were changed according to the line speed. The amount of Si vapor deposited was adjusted to be constant regardless of the line speed. In this example, Si was deposited in an amount such that the average Si concentration including the base material was 6.5 wt'16, and a series of treatments were performed using a thermal cycle shown in FIG. In addition, regarding steel strips with short diffusion treatment time, since the surface layer has a very large amount of Sl-IJ, warm treatment (250 to 3
00℃).

Figure 12 shows the Si6: & degree and re concentration of the cross section in the plate thickness direction measured by XMA for the steel strips as CVD treated and for #4 steel with diffusion times of 5 minutes, 10 minutes, 20 minutes, and 40 minutes, respectively. Si was almost uniformly diffused in the diffusion process (1200° C.) for about 40 minutes.

Figure 13 shows the results of measuring the iron loss, which is a magnetic property, for samples obtained under the same conditions as above but with different diffusion times. It can be seen that sufficiently high magnetic properties almost equivalent to those obtained when Si is uniformly diffused in the Si-diffused state are obtained.

Example 3 The same raw material steel strip as in Example 2 was subjected to CUD treatment in an atmosphere with various 5ict4 concentrations through a continuous process, followed by diffusion soaking treatment at 1200C for 10 minutes, and the degree of residual voids was investigated. The results are shown in Table 1.

Thus, voids were observed to remain at 5tcz, concentration 30%, and 35chi. Therefore, 5 ict, concentration 30%,
For 35 chips, the processing temperature was A) 1200℃ constant x 10 minutes a) 1200℃ x 5 minutes → 1250℃ x 5 minutesC)
1200℃ x 3 minutes → 1250℃ x 3 minutes → 1280℃ x 4
Steel strips were produced by setting the level to 3/3, and the remaining voids in them were investigated. The results are shown in Table 2.

Table 2 By selecting the diffusion treatment conditions as shown above, SiC1
A somewhat satisfactory product can be obtained even with a concentration of 35%.

However, in reality, it is preferable that the SiC4 concentration be 30% or less so that voids can be eliminated by slight temperature control.

〔Effect of the invention〕

According to the present invention described above, a high-silicon steel strip with excellent magnetic properties can be obtained by short-time CVD treatment and diffusion heat treatment in a continuous line. It does not cause problems such as poor shape or edge melting, and in addition, it can improve the toughness of the steel strip without impairing its magnetic properties. (It is possible to efficiently manufacture high-quality, high-silicon copper plates.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams showing continuous processing lines for carrying out the method of the present invention, respectively. Figure 3 shows Fe-8
FIG. 4 (AXB), which is an i-system phase diagram, shows changes in the Si concentration distribution in the thickness direction of the steel strip during the diffusion heat treatment of the present invention. Fig. 5 and Fig. 6 G () (1:9 shows the CVD processing situation using the nozzle spraying method, Fig. 5 is an overall explanatory diagram, Fig. 6 B) and (q indicate the nozzle spraying method, respectively. It is an explanatory diagram. Figure 7 shows the relationship between the 5ict4 concentration in the gas and the steel strip Si enrichment ratio in the CVN treatment,
FIG. 8 shows the relationship between the CVD treatment temperature and the Si enrichment ratio of the steel strip. Figure 9 shows the Si in the present invention.
The relationship between the deposition time and the Si 9 degree in the steel strip is shown by comparing the atmospheric air method and the nozzle spray method. FIG. 1θ shows the relationship between the flow velocity of the atmospheric gas colliding with the steel strip and the Si enrichment ratio of the steel strip during the CVD treatment using the nozzle spraying method. FIG. 11 shows the thermal cycle taken in the example. FIGS. 12(a) to 12(e) show the Si concentration distribution of each sample material in the example. FIG. 13 shows the magnetic properties of each sample material in Example ζ. In the figure, (1) is a heating furnace, (2) is a CVD processing furnace,
(3) is a diffusion treatment furnace, (4) is a cooling furnace, (6) is a coating device, (power is a baking furnace, and (S) is a steel strip. Patent applicant: Nippon Kokan Co., Ltd. Inventor: Tadashi Abe hall
Oka 1) Wa Daido
1) Central patrol
Tadashi Yamato Muroma
High 1) Yoshi - Agent Patent Attorney Sho Yoshihara Masaru Mimukai - Attorney
Hiroko Yoshihara Fig. 4 Si concentration 3X 8.5X Si concentration Fig. 5 Fig. 6
Figure & amendment to bribery procedure (voluntary) Showa ++ 1961 671250 Patent 11 Chief Bi Uga Michibe (special, nli
Bosho IX (Den) I
・Display of 11 items 1986 Patent Application No. 71489 Bow 2, Title of Invention [Method for manufacturing high silicon #I band in III continuation line (4
12) Meki Steel Pipe Co., Ltd. 4 Agent 5, Contents of the 11th Attachment 7 of the HLI Positive Order Amended as per attached Contents/Specification of this application Cattle No. 12 JilO line G At the beginning, ``The surface of the steel strip is'' is changed to `` Corrected to ``on the surface of the steel strip.''

Claims (2)

[Claims] (1) Steel strip with SiCl_4 in a mol fraction of 5 to 35%
In a non-oxidizing gas atmosphere containing SiCl_4, silicon was continuously treated by chemical vapor deposition at a temperature of 1023 to 1200°C, and then S in a non-oxidizing gas atmosphere containing no SiCl_4.
When conducting the diffusion treatment to diffuse i into the steel strip, the diffusion treatment is stopped while the surface layer Si concentration is higher than the Si concentration at the center of the steel strip in the thickness direction, so that the Si concentration is non-uniform in the thickness direction. 1. A method for producing high-silicon steel strip in a continuous line, characterized by obtaining a steel strip with high silicon content. (2) Steel strip with SiCl_4 at a mol fraction of 5 to 35%
In a non-oxidizing gas atmosphere containing SiCl_4, silicon was continuously treated by chemical vapor deposition at a temperature of 1023 to 1200°C, and then S in a non-oxidizing gas atmosphere containing no SiCl_4.
When conducting the diffusion treatment to diffuse i into the steel strip, the diffusion treatment is stopped while the surface layer Si concentration is higher than the Si concentration at the center of the steel strip in the thickness direction, so that the Si concentration is non-uniform in the thickness direction. 1. A method for producing a high-silicon steel strip in a continuous line, which comprises obtaining a high-silicon steel strip, which is then cooled, coated with an insulating film, and subjected to a baking treatment.