JPH0617133A - Production of grain-oriented silicon steel sheet having uniform magnetism even in the case of heavy weight coil - Google Patents

Abstract

PURPOSE:To produce a grain-oriented silicon steel sheet having uniform magnetism even in the case of heavy weight coil. CONSTITUTION:At the time of producing a grain-oriented silicon steel sheet, the joining between a roughed sheet bar or a sheet bar cast to the thickness equal to that of the roughed bar by means of rapid solitification and a sheet bar in the course of finish rolling is completed at a temp. not lower than a metallurgically determined temp. and finish hot rolling is done continuously while limiting the temp. hysteresis before the entrance of a coil into a continuous finish hot rolling mill and the temp. region where finish hot rolling is finished, respectively. By this method, magnetism uniform in a longitudinal direction can be obtained even if the weight of the coil is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a grain-oriented electrical steel sheet, and more particularly to a hot rolling method for its slab.

[0002]

2. Description of the Prior Art Grain-oriented electrical steels used for transformers and various other electric devices are required to have high magnetic flux density and low iron loss. To meet this requirement, {110}
It is necessary to obtain secondary recrystallized grains having an orientation close to the <001> orientation (so-called GOSS orientation).

In order to obtain secondary recrystallized grains integrated in the GOSS direction, MnS, AlN, called an inhibitor,
It is necessary to deposit a precipitate such as MnSe in a proper amount and a proper size. The distribution of these precipitates in the magnetic steel sheet is greatly influenced by the heat and working history until the steel sheet is obtained.

Conventionally, as a combination of precipitates used as an inhibitor for grain-oriented electrical steel sheets, N.
P. A method using MnS proposed by Goss (US Patent 1965559, (193
4)), a method using AlN and MnS proposed by Taguchi et al. (Japanese Patent Publication No. 33-4710) and a method using MnSe or MnS and MnSe proposed by Imai et al. (Japanese Patent Publication No. 36-17154). There is. Among these technologies, currently the best {110} <001>
It is the method using AlN and MnS that can obtain the orientation integration degree, but this method is industrially the most difficult from the viewpoint of controlling the precipitates.

In the case of producing a high magnetic flux density grain-oriented electrical steel sheet using AlN and MnS as inhibitors, Mn
The concept of controlling the state of precipitation of S and AlN is as follows.
Regarding AlN, a basic guideline is presented in Japanese Patent Laid-Open No. 48521/1978. First, AlN is completely solid-soluted before hot rolling, and then rapidly cooled below the precipitation temperature so as not to precipitate AlN during hot rolling. To do. AlN precipitation nose is IWA
YAMA et al. (J. Magnetism and Mag)
netic Materials, 19 (1980),
As indicated by 15), it is 1130 to 1160 ° C., and in reality, rough rolling is completed at a temperature higher than this temperature range, and this temperature range is rapidly cooled during finish rolling.

The above thermal history is {110} of the final product.
When the temperature of the rear part of the coil is lowered due to an extremely large effect on the <001> orientation integration degree, for example, the unit weight of the hot-rolled coil becomes large and rolling takes a long time, secondary recrystallization defects called fine grains occur in the part. Occurs.

Regarding MnS when used in combination with AlN,
Japanese Unexamined Patent Publication No. 48-69720 discloses a basic guideline. First, MnS is completely dissolved before hot rolling, and then,
Precipitate during hot rolling to secure the required amount of MnS. The precipitation nose of MnS is 116 as shown by IWAYAMA et al.
0-1200 ℃, so the actual bar is 1200 ℃
Then, hot rolling is performed so that the temperature is maintained in a temperature range of 950 ° C. or higher for a certain period of time.

The difficulty in operation when AlN and MnS are used in combination is that the temperature difference between the precipitation noses of the two is extremely small. Therefore, if rolling is carried out for a sufficient time to precipitate MnS, a rough bar or finish will be produced. Fine particles are generated due to AlN precipitation due to the temperature drop of the coil during rolling.
To avoid precipitation of MnS
The reason is that the magnetic flux density is lowered due to the insufficient precipitation of.

Therefore, in the conventional hot rolling technique, if the slab weight is increased, it is difficult to obtain a uniform heat history in the longitudinal direction of the hot rolled coil, and the fine grain or the magnetic flux density is lowered as described above, so that the coil weight is limited. There was a decrease in productivity and yield.

A based on the difference in thermal history of the coil in the longitudinal direction
In order to eliminate the difference in the precipitation state of 1N, JP-A-58-164725 discloses a technique of changing the cooling rate after hot-rolled sheet annealing between a high coil finishing temperature region and a low coil finishing temperature region. With this technique, it is possible to eliminate the magnetic fluctuation due to the variation of the AlN precipitation state in the longitudinal direction of the coil to some extent. However, when the weight of the coil increases and the difference in the thermal history in the longitudinal direction increases, this technique can no longer eliminate the magnetic variation. Disappear.

Further, as a measure for reducing the difference in heat history in the longitudinal direction of the hot rolled coil, there is a method of heating the slab rear end so as to be higher than the front end by 200 ° C. or less when heating the slab. It is proposed in Japanese Patent No. 193216. However, the slab heating temperature is extremely high for complete solid solution of MnS, and there is little room for further raising the temperature. Moreover, the crystal grains become coarse in the high temperature heating part, and the linear slab in the product is called a line mixture. Since the secondary recrystallization defect portion is generated, there is a limit to the compensation of the temperature decrease at the coil rear end portion due to the slab heating temperature up.

Further, as another measure for reducing the difference in heat history in the longitudinal direction of the hot rolled coil, the rolling speed at the trailing end side is made faster than the rolling speed at the leading end side of the slab during hot rolling, and the rolling time at the trailing end portion is increased. Japanese Patent Application Laid-Open No. 59-208021 proposes a technique for preventing the temperature drop at the rear end of the coil by shortening the length. This technique is effective, but when the slab tip bites into the roll, the slab rolling speed must be reduced in order to avoid bite failure, and during that time the temperature drop at the slab rear end is unavoidable. After all, there is a limit to increasing the coil weight.

When only MnS is used as an inhibitor, the restrictions on the temperature history during hot rolling due to the avoidance of AlN precipitation are alleviated, but MnS of the required amount and size during hot rolling should also be precipitated. Is required, and if the weight of the slab increases, the Mn that is uniform in the longitudinal direction of the coil
It becomes difficult to obtain the S precipitation state.

When MnS and MnSe are used in combination, it is necessary to finely and uniformly precipitate MnS and MnSe as disclosed in JP-A-51-20716, and for that reason, it is a precipitation nose of MnSe. 950-1
It is necessary to increase the cooling rate while keeping the coil temperature in the range of 200 ° C. and preventing the precipitated MnSe from coarsening.

If the precipitation quenching treatment in this case is to be carried out at the stage of the rough bar before entering the continuous finishing hot rolling machine, not only the cooling efficiency is bad but also the temperature difference in the plate thickness direction is caused due to the thick plate thickness. Occurs, resulting in nonuniform deposition of MnSe between the plate surface layer and the center layer.

[0016] Therefore, in operation, rough rolling is completed in a high temperature range where MnSe does not precipitate, and MnSe is finely and uniformly dispersed using lattice defects generated by rolling during continuous hot rolling as precipitation sites. Also in this case, when the coil weight becomes large, it takes a long time for rolling, so that rolling and cooling of the rear portion of the coil cannot be performed in time and MnSe becomes coarse.
The magnetic flux density decreases.

[0017]

DISCLOSURE OF THE INVENTION The present invention, in the conventional technique of hot-rolling steel strips one by one, has a directional magnetic steel sheet coil which is inevitable when a heavy coil is used. It is an object of the present invention to provide a method for producing a grain-oriented electrical steel sheet, which eliminates the magnetic defect based on the above, and industrially stably obtains an electrical steel sheet having excellent magnetism while improving productivity and yield.

[0018]

Means for Solving the Problems The inventors of the present invention have conducted extensive experiments in order to eliminate the non-uniform heat history in the coil longitudinal direction in the conventional hot rolling technique, and as a result, the sheet bar roughly rolled or rapidly solidified. Before joining the sheet bar cast into the same thickness as the rough bar and the sheet bar during finish rolling at a temperature not lower than a certain metallurgically determined temperature and before the coil enters the continuous finishing hot rolling machine. The present invention has been completed by finding out that even if the coil weight becomes large, uniform magnetism can be obtained in the longitudinal direction by limiting the temperature history of and the temperature range for completing the finish hot rolling. It was made.

The joining method in this case is a known means.
That is, a method of joining by flash welding disclosed in Japanese Patent Laid-Open No. 54-4842, Japanese Patent Publication No. 59-37.
Japanese Patent Laid-Open No. 861 discloses a method in which a preceding steel piece and a trailing steel piece are overlapped by a predetermined amount and pressure-welded by a press machine.
The method by laser beam welding described in Japanese Patent Laid-Open No. 130603, or the method disclosed in Japanese Patent Laid-Open No. 61-159285, in which both sheet bars are butted and then the butted portions are electrically heated and pressure-welded.

In hot rolling, a technique of joining a sheet bar having a finite length between a rough rolling mill and a finish rolling mill to perform endless finish rolling has already been proposed (the above-mentioned published patent publications relating to the joining method). However, these are all intended for thin plates, stainless steel, etc., and are intended to improve productivity, reduce product plate thickness dimension variation, make product material uniform, and enable high-tensile rolling. By applying it to the production of grain-oriented electrical steel sheets for the first time, it has been newly found that it is possible to produce grain-oriented electrical steel sheet with uniform magnetism in the longitudinal direction of the coil while using a large weight coil, which was impossible with the conventional method. It is a thing.

That is, in continuous endless rolling of the joined sheet bars, two points are taken into account: increasing the rolling speed and increasing the finishing temperature over the entire length of the coil as compared with the conventional hot rolling technique. As a result, it has been newly found that even when the coil weight is increased, it is possible to reduce the difference in temperature history between the front end portion and the rear end portion of the coil as compared with the conventional technique, and as a result, no magnetic difference occurs. According to the present invention, since the weight of the coil can be increased and the hot rolling can be continuously performed, the productivity and the yield can be remarkably improved.

The electromagnetic steel rough-rolled sheet bar used in the present invention is obtained by ingoting a molten metal refined by a known steelmaking method such as a flat furnace, a converter, an electric furnace, a bottom blowing converter, or continuous casting. It means a slab containing the component range of the present invention, heated in a heating furnace, or directly rough-rolled after continuous casting. Further, a raw material cast into a thickness equal to that of the rough sheet bar by a rapid solidification method such as twin belts, twin rolls, single belts may be used.

Next, the reasons for limiting the components of the present invention will be described. Si needs to be contained in at least 2% in order to increase the specific resistance and to obtain the low iron loss required for electromagnetic steel sheets, and addition of Si in excess of 7% not only makes rolling industrially difficult. However, the saturation magnetic flux density is lowered and the magnetic steel sheet becomes unsuitable for use as an electrical steel sheet, so the content was set to 2.0% to 7.0%.

C is γ in the Fe-Si alloy which is an α single phase.
It is added to form a phase and suppress the occurrence of secondary recrystallization defects by refining the cast structure and hot rolled structure, and contribute to the formation of texture before secondary recrystallization, but 0.09%
If it is added in excess of 10%, decarburization annealing will take time, resulting in a significant decrease in productivity, so the content was limited to 0.09% or less. However, the effect of the present invention is not necessarily limited to the case where C is included, and therefore the lower limit of C is not particularly set.

Mn is an important element that forms MnS and acts as an inhibitor. MnS alone or MnS and Al
At least 0.0 if N is used as an inhibitor
3% Mn is required, and 0.01% Mn is required when MnS and MnSe are used as inhibitors.

However, addition of Mn in excess of the required amount will strengthen the inhibitor too much and secondary recrystallization will not occur, so MnS alone or MnS and Mn will not occur.
The upper limit was 0.2% when Se was used as an inhibitor, and the upper limit was 0.09% when strong AlN was used in combination.

Similar to Mn, S forms MnS and acts as an inhibitor, but at least 0.005% is required to effectively suppress the growth of primary recrystallized grains.
When nS alone or MnS and MnSe are used as inhibitors, addition of S exceeding 0.1% causes 0.005 to 0.1% because hot cracking occurs during hot rolling.

When AlN and MnS are used as inhibitors, the upper limit of S is 0.03% because the upper limit of S is smaller than that of the above two inhibitors because AlN has a strong grain growth inhibitory effect.

Al forms AlN and acts as an inhibitor, but at least 0.01% is necessary for effectively suppressing the growth of primary recrystallized grains, and 0 for expressing secondary recrystallization. It must be 0.07% or less.

N forms AlN like Al and acts as an inhibitor, but at least 0.003% is necessary to effectively suppress the growth of primary recrystallized grains.
If added in excess of 0.01%, surface defects called blister will occur, so the content was made 0.003 to 0.01%.

Se forms MnSe and acts as an inhibitor. At least 0.005% is necessary to effectively suppress the growth of primary recrystallized grains, but 0.1% is added for economic reasons. The upper limit was set.

Sb is added because it coexists with MnS and MnSe to bring about a stronger grain growth suppressing effect, and the addition of more than 0.2% is meaningless, so the upper limit is 0. It was set to 0.2%. However, the effect of the present invention is not necessarily limited to the case where Sb is included.

Next, the reason for limiting the temperature range in which the joined sheet bars are kept warm will be described. ◎ When only MnS is used as an inhibitor, if the precipitation of MnS is attempted during finish rolling, the coil longitudinal temperature drop due to the thinning of the coil is remarkable and a uniform precipitation state cannot be obtained. Before entering the continuous finishing hot rolling machine in a state where the rough sheet bar and the finishing sheet bar are joined, the precipitation nose of MnS is 1200 to 95.
By maintaining the temperature range of 0 ° C for a certain period of time, MnS
A sufficient amount of uniform precipitation state can be obtained. The holding time is required to be at least 25 seconds, and holding for a long time not only impairs the productivity of continuous hot rolling but also causes coarsening of MnS, so the upper limit was set to 180 seconds.

When AlN and MnS are used as inhibitors, it is important not only to precipitate MnS before entering the continuous finishing hot rolling machine but also to prevent AlN from being precipitated during finish rolling. Since AlN forms a solid solution in the γ phase ten times or more than in the α phase, the precipitation temperature range of AlN fluctuates depending on the amount of γ determined by the amounts of the components C and Si. In the case of normal 3.2% Si and 0.05% C, the maximum γ amount is 30%
The precipitation nose of AlN reaches 1130-1160 ° C. Therefore, in this case, the sheet bar is kept at 1100 ° C or higher, preferably 1130 ° C to 1200 ° C, and the finish hot rolling is completed at 1050 ° C or higher, preferably 1100 to 1200 ° C.

The upper limit of the heat retention temperature range of the sheet bar is determined by the maximum Si amount and the minimum C amount described in the range of the present invention, and the lower limit is determined by the combination of the minimum Si amount and the maximum C amount. That is, the maximum γ when containing 2% Si and 0.09% C
The amount is almost 100%, and the sheet bar holding temperature is 80%.
A, even if the finishing hot rolling completion temperature is lowered to 0 ° C to 750 ° C
It is possible to avoid the precipitation of 1N.

On the other hand, when the C content is not included and 7% of Si is contained, the α single phase is formed, so that the sheet bar holding temperature is 12
It is necessary to set the temperature to 00 to 1250 ° C and complete the hot rolling at 1150 ° C or higher. The maximum γ amount continuously changes from 0 to 100% in the Si and C component ranges, and the precipitation of AlN can be avoided by setting the above-mentioned temperature as the upper limit and the lower limit. 800-1250
℃, the finish rolling temperature was 750 ℃ or more.

When MnS and MnSe are used as inhibitors, before entering the continuous finishing hot rolling machine in a state where the rough sheet bar and the finishing sheet bar are joined, a temperature range higher than 1200 to 950 ° C. which is the precipitation nose of MnSe, that is, 10
By maintaining the temperature range of 50 to 1250 ° C. and finishing hot rolling at 950 ° C. or higher so that the precipitation nose of MnSe may be applied during the subsequent hot rolling for finishing, a sufficiently uniform fine precipitation state of MnSe can be obtained.

The present invention will be specifically described with reference to the embodiments. FIG. 1 shows the results of measuring the iron loss at the leading end and the trailing end of coils having different weights by hot rolling using MnS and AlN as inhibitors by the conventional method and the method of the present invention.

In the conventional method, a portion where the iron loss is bad occurs at the rear end of the coil due to the secondary recrystallization defect due to the temperature decrease. According to the method of the present invention, the iron loss is caused at the coil front end and the rear end. Does not make a big difference.

FIG. 2 shows the case where MnS and MnSe are used as inhibitors, and it can be seen that the method of the present invention eliminates the non-uniformity of the magnetism at the front and rear ends of the coil.

FIG. 3 shows the case where only MnS was used as an inhibitor, and it can be seen that the method of the present invention also eliminates the non-uniformity of the magnetic properties at the front and rear ends of the coil.

[0042]

【Example】

[Example 1] Molten steel containing Si; 3.25 wt%, C; 0.06%, acid-soluble Al; 0.026 wt%, N; 0.008 wt% was continuously cast into a slab. After heating to 1380 ° C., a part of the slab was roughly rolled and finish-rolled by a usual method to obtain a hot rolled sheet having a sheet thickness of 2.3 mm.

In the finish hot rolling, the rolling speed was slowed down when the bar was caught, so that the temperature difference between the coil front end portion and the coil rear end portion when the rolling was completed was 62 ° C.

After the rough rolling, the remaining slabs were completely welded at 1200 ° C., and at 1180 ° C., the sheet bars were continuously hot-rolled so that the sheet bar was caught in the finishing rolling mill to obtain a sheet thickness of 2.
A 3 mm hot rolled sheet was used.

In continuous rolling, the rolling speed in the steady rolling portion was increased by 12% as compared with the conventional method, and as a result, the temperature difference between the coil front end portion and the rear end portion became 34 ° C. The hot-rolled sheet produced by both methods was annealed at 1120 ° C. and then cold-rolled once to 0.23 mm. After decarburization annealing at 830 ° C. in wet hydrogen, an annealing separator was applied and finish annealing was performed in a coil shape. The magnetic properties of the product were measured on a 300 mm x 60 mm veneer sample.

The obtained results are shown in FIG. In the conventional method, deterioration of iron loss, which is considered to be caused by fine grains, is recognized in the tail portion of the coil, whereas according to the method of the present invention, the iron loss value as excellent as that of the tip portion can be obtained in the tail portion. FIG. 4 is a macro photograph of the coil tip and tail. In the conventional method, the secondary recrystallized grains are sufficiently grown at the tip part, whereas the fine grains are generated at the tail part due to the decrease in coil temperature during hot rolling.
On the other hand, in the case of the method of the present invention, the temperature difference between the coil tip portion and the tail portion is 34 ° C., which is smaller than that of the conventional method by about 30 ° C. Therefore, secondary recrystallized grains grow sufficiently in the coil tip portion and the tail portion. You can see that

[Example 2] Si: 3.1%, C: 0.0
46%, Mn; 0.07%, S; 0.020%, Se:
Molten steel containing 0.010% was continuously cast into a slab. After heating at 1370 ° C., a part of the slab was rough-rolled and finish-rolled by an ordinary method to obtain a hot-rolled plate having a plate thickness of 3.3 mm.
Upon finish hot rolling, the temperature difference between the coil front end and the coil rear end at the time of completion of rolling was 60 ° C. After the rough rolling, the remaining slabs were welded at 1250 ° C and continuously hot-rolled at 1100 ° C so that the sheet bar was caught in the finishing rolling mill to form a hot-rolled sheet with a thickness of 3.3 mm. did.

In this case as well, the finish rolling speed is set to 1 compared with the conventional method.
As a result of the increase of 2%, the temperature difference between the front end portion and the rear end portion of the coil was 31 ° C. The hot rolled sheet produced by both methods is 0.88
It was cold-rolled to mm and subjected to intermediate annealing at 900 ° C. for 5 minutes.
After pickling, the product was further cold rolled to 0.35 mm and decarburized and annealed at 810 ° C. in wet hydrogen.

After the annealing separator was applied, finish annealing was performed in a coil shape, and magnetic measurement was performed on a 300 mm × 60 mm single plate sample. The results are shown in Figure 2. In the conventional method, deterioration of iron loss, which is considered to be caused by coarsening of MnSe, is recognized in the coil tail portion, whereas according to the method of the present invention, an excellent iron loss value can be obtained in the tail portion as in the tip portion.

[Example 3] Si: 3.1%, C: 0.0
Molten steel containing 46%, Mn: 0.07%, S: 0.020% was continuously cast into a slab of 20,40 tons. 1
After heating at 370 ° C., a part of the slab was rough-rolled and finish-rolled by a usual method to obtain a hot-rolled plate having a plate thickness of 2.5 mm. In the finish hot rolling, the temperature difference between the coil front end and the coil rear end at the time of completion of rolling was 66 ° C. After the rough rolling, the remaining slabs were welded at 1250 ° C, and at 1150 ° C, finish hot rolling was performed continuously so that the sheet bar was caught in the finishing rolling mill to form a hot rolled sheet with a thickness of 2.5 mm. did.

In this case as well, the finish rolling speed is set to 1 compared with the conventional method.
As a result of the increase of 2%, the temperature difference between the front end portion and the rear end portion of the coil became 32 ° C. The hot-rolled sheet produced by both methods was 0.67
It was cold-rolled to mm and subjected to intermediate annealing at 900 ° C. for 5 minutes.
After pickling, the product was further cold rolled to 0.30 mm and decarburized and annealed at 810 ° C. in wet hydrogen.

After the annealing separator was applied, finish annealing was performed in a coil shape, and magnetic measurement was performed on a 300 mm × 60 mm single plate sample. The results are shown in Fig. 3. In the conventional method, deterioration of iron loss, which is considered to be caused by coarsening of MnS, is recognized in the tail of the coil.
According to the method of the present invention, it is possible to obtain an excellent iron loss value in the tail portion as in the tip portion.

[0053]

EFFECTS OF THE INVENTION According to the present invention, not only the magnetic defect due to the thermal history difference in the longitudinal direction of the coil is eliminated, and the grain-oriented electrical steel sheet which is industrially stable and has excellent magnetic characteristics is obtained. By increasing the weight, productivity and yield can be increased, so its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a chart showing a relationship between a coil position and iron loss according to the present invention.

FIG. 2 is a chart showing a relationship between coil position and iron loss in another example of the present invention.

FIG. 3 is a chart showing the relationship between coil position and iron loss in still another example of the present invention.

4 (a) and 4 (b) are macrophotographs of a coil front end portion (a) and a rear portion (b).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Kouei Nakajima 20-1 Shintomi, Futtsu City Nippon Steel Corporation Technical Development Division

Claims (4)

[Claims] 1. In the production of a grain-oriented electrical steel sheet, the rear end portion of the preceding rolled material and the leading end portion of the following rolled material are joined at the entry side of the hot rolling finish rolling mill, and continuous finish hot rolling is performed. A method of manufacturing a grain-oriented electrical steel sheet with a large weight and uniform magnetism. 2. By weight% Si; 2.0 to 7.0% C; 0.09% or less sol-Al; 0.01 to 0.07% N; 0.003 to 0.010% Mn; 0 An electromagnetic steel slab containing 0.03 to 0.09% S; 0.005 to 0.03% is heated, hot-rolled, hot-rolled and annealed, and then cold rolled one or more times to obtain the final thickness. In the method for producing a grain-oriented electrical steel sheet subjected to decarburization annealing and further finish annealing, a sheet bar roughly rolled at the time of hot rolling or a sheet bar cast to a thickness equal to the rough bar by quench solidification and finish rolling Joining with the sheet bar of No. 2 is completed in a temperature range in which AlN does not precipitate, and the sheet portion before entering the continuous finishing hot rolling machine is maintained in a temperature range of 800 to 1250 ° C depending on the amounts of Si and C, and 750 ° C or more. Of the grain-oriented electrical steel sheet characterized by continuously finishing rolling in Production method. 3. An electromagnetic steel slab containing, by weight%, Si; 2.0 to 7.0% C; 0.09% or less Mn; 0.03 to 0.20% S; 0.005 to 0.10%. After hot-rolling after heating, after cold rolling one or more times to the final plate thickness, decarburization annealing, further in the method for producing a grain-oriented electrical steel sheet subjected to finish annealing, rough rolling during the hot rolling. Before completion of joining of a sheet bar or a sheet bar cast into a thickness equal to the rough bar by rapid solidification and a sheet bar during finish rolling in a temperature range where MnS does not precipitate and before entering a continuous finishing hot rolling machine Sheet part of 1200 ℃
A method for producing a grain-oriented electrical steel sheet, which comprises continuously performing hot rolling while maintaining a temperature range of 950C to 950C for 25 seconds to 180 seconds. 4. By weight%, Si; 2.0 to 7.0% C; 0.09% or less Mn; 0.01 to 0.20% Any one or two kinds of S and Se; 005
~ 0.10% If necessary, an electromagnetic steel slab containing 0.2% or less of Sb is heated, hot-rolled, cold-rolled one or more times to obtain the final plate thickness, and then decarburized and annealed. In a method of manufacturing a grain-oriented electrical steel sheet to be annealed, joining of a sheet bar roughly rolled at the time of hot rolling or a sheet bar cast to a thickness equal to the rough bar thickness by rapid solidification and a sheet bar during finish rolling Is completed in a temperature range where MnSe does not precipitate, and the sheet portion before entering the continuous finishing hot rolling machine is heated to 1050 ° C.
The manufacturing method of the grain-oriented electrical steel sheet characterized by holding | maintaining in the temperature range of -1250 degreeC, and performing finish rolling continuously at 950 degreeC or more.