JP2001181743A - Method for producing hot-rolled silicon steel sheet excellent in magnetism - Google Patents

Abstract

(57) [Problem] To provide a hot-rolled silicon steel sheet excellent in magnetism. SOLUTION: In a method for producing a silicon steel sheet by hot-rolling steel containing Si, Mn, C, N, and P in a specific range, after finishing hot rolling, the first winding temperature is 750 ° C. or more, 1
It is characterized by winding once at 050 ° C. or lower, holding for 30 seconds or more and 90 minutes or less, rewinding, cooling, and winding again at a temperature of 550 ° C. or lower.

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 hot-rolled silicon steel sheet having a low iron loss and a high magnetic flux density and excellent magnetism, and a non-oriented electrical steel sheet excellent in magnetism using the hot-rolled steel sheet. And a method for producing the same.

[0002]

2. Description of the Related Art In recent years, in a rotating machine in which non-oriented electrical steel sheets are used as its core material, the trend toward higher efficiency has rapidly spread in the world of power, energy saving and environmental conservation. It is getting. For this reason, there has been an increasing demand for non-oriented electrical steel sheets to have improved properties, that is, higher magnetic flux density and lower iron loss. Also, as the world is entering the era of global competition, consumers are strongly demanding the provision of non-oriented electrical steel sheets with low cost and excellent magnetic properties.

[0003] Meanwhile, in non-oriented electrical steel sheets, conventionally, as a means of reducing iron loss, generally, a method of increasing the content of Si or Al or the like has been taken from the viewpoint of reducing eddy current loss due to an increase in electric resistance. However, this method has a problem that the magnetic flux density cannot be reduced. In order to overcome such problems, a method of improving both the magnetic flux density and the iron loss by increasing the crystal grain size of the hot-rolled sheet has been performed.

As a technique for inexpensively coarsening the crystal structure before cold rolling of a non-oriented electrical steel sheet according to the prior art, Japanese Patent Laid-Open Publication No.
No. 74222 discloses a technique in which the rolling reduction of a hot-rolled sheet is set to 700 ° C. or higher by setting the rolling reduction of the final hot-rolled final stand to 20% or more. In this technique, the aim is to increase the final stand draft and raise the winding temperature to promote recrystallization and grain growth of the hot-rolled structure after hot-rolling, thereby improving magnetic properties. .
However, this technique has a problem that although recrystallization of the hot-rolled sheet is promoted, subsequent grain growth is insufficient.

Japanese Patent Application Laid-Open No. 54-76422 discloses a self-annealing method in which a hot-rolled sheet after finish hot rolling is wound at a high temperature of 700 ° C. to 1000 ° C. and annealed by the heat retained in the coil. ing. However, in this technique, there was a problem that magnetic characteristics in the longitudinal direction of the coil fluctuated due to uneven temperature in the coil caused by winding the coil at a high temperature.

As means for providing a low-cost non-oriented electrical steel sheet, Japanese Patent Application Laid-Open No. 9-194939 discloses a method in which after rough hot rolling, a sheet bar is wound and subjected to a uniform heat treatment,
A technique for producing a hot final non-oriented electrical steel sheet having a thickness of 1 mm or less is disclosed. However, there is a limit to the stable production of thin hot rolled sheets only by soaking the sheet bar itself by winding the sheet bar, and when thin materials are manufactured, the rolling reduction of the finished hot rolling increases. , When the seat bar bites, warp easily occurs between stands,
As a result, rolling had to be stopped.

Further, if the sheet bar is made thinner to reduce the rolling reduction of the hot-rolled finish, even if the sheet bar is wound up, it is not possible to eliminate the unevenness in the temperature of the sheet bar. There is a limit to achieving stable magnetism without being stable with respect to the position in the coil. Thus, the production of a thin hot-final non-oriented electrical steel sheet has a great problem.

Japanese Patent Application Laid-Open No. Hei 10-226854 discloses a technique for increasing the rolling reduction of the final pass of finish hot rolling to 50% or more when manufacturing a hot rolled silicon steel sheet. However, in the hot rolled silicon steel sheet used for lamination, it is necessary to control the thickness accuracy more strictly than in a normal hot rolled steel sheet, and a high pressure reduction rate of 30% or more near the final pass of finish hot rolling is required. In this case, there is a problem that the thickness accuracy is significantly deteriorated. As described above, conventional production techniques have not been able to produce a non-oriented silicon steel sheet which is inexpensive and excellent in magnetism.

[0009]

SUMMARY OF THE INVENTION The present invention solves the problems of the conventional method for producing a non-oriented silicon steel sheet which causes an increase in cost,
A main object of the present invention is to provide a method for stably producing a thin hot final non-oriented silicon steel sheet which is inexpensive and has excellent magnetic properties.

[0010]

The gist of the present invention is as follows. (1) By weight%, 0.1% ≦ Si ≦ 4%, 0.1% ≦
Mn ≦ 1.5%, C ≦ 0.05%, N ≦ 0.01%,
In a method for producing a silicon steel sheet by hot-rolling a steel containing P ≦ 0.15%, the balance being Fe and unavoidable impurities, the first winding temperature after finishing hot-rolling is 750 ° C. or higher.
A hot-rolled silicon steel sheet excellent in magnetism characterized by being wound once at 050 ° C. or less, held for 30 seconds or more and 90 minutes or less, then unwound, cooled and wound again at a temperature of 550 ° C. or less. Production method. (2) The lower limit of the above-mentioned first winding temperature is defined as X defined by the following formula (1) by the hot rolling end temperature FT, and the magnetism is excellent in the above item (1). A method for manufacturing a hot-rolled silicon steel sheet. X = 0.67 × FT−20 × FT ^0.5 +780 (1) Formula (3) In the above-mentioned finishing hot rolling, at least one pass in the α phase region is reduced by 10% or more, and the hot rolling end temperature is obtained. 75
The method for producing a hot-rolled silicon steel sheet excellent in magnetism according to the above (1) or (2), wherein the temperature is 0 ° C. or more and the Ar 1 point or less. (4) The production of a hot-rolled silicon steel sheet excellent in magnetism according to any one of the above (1) to (3), further using a steel containing 0.1 to 2.5% of Al. Method. (5) The production of a hot-rolled silicon steel sheet excellent in magnetism according to any one of the above (1) to (4), further using a steel containing 1.5 or less of B in B / N. Method. (6) The method for producing a hot-rolled silicon steel sheet excellent in magnetism according to any one of the above (1) to (5), further comprising using steel containing 0.1% or less of Sn. (7) The sheet bar after the rough rolling is joined to the preceding sheet bar before the hot rolling, and the connected sheet bar is continuously subjected to the hot rolling. 6) The method for producing a hot-rolled silicon steel sheet having excellent magnetism according to any one of the above items. (8) The hot-rolled silicon steel sheet produced by the method according to any one of (1) to (7) is further subjected to pickling and cold rolling, followed by recrystallization annealing. A method for manufacturing non-oriented electrical steel sheets with excellent magnetism.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
First, the conditions for limiting the components will be described. Si is added for the purpose of improving iron loss. For this purpose, an addition amount of 0.1% or more is required. On the other hand, if the Si content exceeds 4%, ear cracks occur during hot rolling, so the content is set to 4% or less.

Mn provides iron loss improvement like Si.
However, if the content is less than 0.1%, the effect of addition cannot be obtained, so the content is made 0.1% or more. On the other hand, if the content exceeds 1.5%, the hot rollability deteriorates.

Although it is preferable that C is small in order to reduce iron loss, in the process of the present invention, the effect of improving iron loss up to 0.05% was confirmed, so the upper limit was made 0.05%.

It is better that N is small in order to improve iron loss, and the upper limit of the steel of the present invention is 0.01%. In particular, Al
To reduce the iron loss by suppressing the precipitation of N, add B to
It is desirable to precipitate N. In this case, if B / N exceeds 1.5, excess B deteriorates the magnetism. Therefore, the upper limit of B is set to 1.5 in B / N.

If the steel of the present invention has a low content of Si, the steel sheet becomes too soft to prevent the punching operation from becoming difficult.
Is added. Although the addition of P also improves iron loss,
If the addition exceeds 0.15%, the hot workability is deteriorated, and there is a risk that hot rolling cracks may occur.
And

There is no problem even if Al in the steel is at the impurity level, but Al has the effect of increasing the specific resistance of the steel sheet and reducing the eddy current loss similarly to Si, so that a particularly low iron loss is obtained. If desired, it is preferable to add 0.1% or more and 2.5% or less. When a large amount of Al is added, the magnetic flux density is reduced and the cost is increased.

Since Sn is also an element which improves magnetism, it may be added. However, the upper limit is set to 0.1% in order to suppress the cost of alloy addition.

Next, the limitation of the process conditions will be described.
In the present invention, by making the hot-rolled sheet crystal grain size of an appropriate size at the time of the first winding and lowering the temperature of the second winding,
Suppresses the development of scale layers on the steel sheet surface. In addition, in order to suppress fluctuations in magnetism in the coil, it is particularly effective to join the sheet bar after the rough rolling to the preceding sheet bar and continuously perform hot rolling.

The first winding temperature is 1050 ° C. or less, 75
The condition of holding at a temperature of 0 ° C. or more for a time of 30 seconds or more and 90 minutes or less is a limiting condition necessary for obtaining the above-described appropriate hot-rolled sheet particle size. The reason for limiting the first winding temperature and the upper limit of the holding time is to suppress the amount of the scale layer formed on the surface of the hot rolled sheet. Further, the lower limit of the first winding temperature and the lowering of the holding time is because below this, the grain size of the hot-rolled sheet is small and the magnetism of the hot-rolled silicon steel sheet is not sufficiently improved. Applying a heat insulating cover to the coil after winding is effective in reducing variations in the coil longitudinal direction.

The reason why the second winding temperature is limited to a temperature of 550 ° C. or less is that the state of C is cold-rolled at a temperature lower than 550 ° C., which is advantageous for forming a texture that improves the magnetic properties of the product sheet during annealing. To work.

Such a hot rolling and winding process is performed by a coiler relatively close to a finishing mill, and then the RO
It is realized by rewinding to T (Run-out Tab1e) and rewinding with a conventional coiler. The present process not only improves the electromagnetic properties of the steel of the present invention, but also avoids the drawback of thickening the scale, which has been a problem during conventional high-temperature winding.

The condition that the film is wound once at a temperature satisfying the expression (1) and held for a period of 30 seconds to 90 minutes is a limiting condition for obtaining an appropriate hot-rolled sheet particle size.
The reason why the winding temperature is set in the range of the equation (1) is that the higher the finishing temperature, the larger the recrystallized grain size and the smaller the driving force required for grain growth. It is necessary to promote it.

As another possible measure, in the finish hot rolling, at least one pass is rolled at 10% or less in the α phase region, and the hot rolling end temperature is set to 750 ° C. or more and Ar 1 point or less. It was found to improve the electromagnetic properties of steel. In addition, using a hot-rolled steel sheet manufactured by any of the above methods, following a normal non-oriented electrical steel sheet manufacturing process, after pickling and cold rolling, and then performing recrystallization annealing, a non-magnetic sheet excellent in magnetism was obtained. It was also confirmed that a grain-oriented electrical steel sheet was obtained.

[0024]

Next, an embodiment of the present invention will be described. (Example 1) Steel having the components shown in Table 1 was melted and hot-rolled for finishing. In the comparative example, the thickness of the hot-rolled sheet was set to 2.5 mm, finished to 0.65 mm by cold rolling, and subjected to finish annealing at 750 ° C. for 30 seconds. In the example of the wood invention, the steel sheet was thinned to a thickness of 0.65 mm at 900 ° C. by finish hot rolling, and was wound at 860 ° C. as the first winding. Thereafter, the coil was kept at 830 ° C. for 30 minutes, then unwound, cooled, and wound at 400 ° C. Thereafter, the hot-rolled steel sheet was subjected to pickling. Epstein samples were cut out from both samples, and their magnetic flux densities were measured. Table 2 shows the measurement results. Table 2 shows that the value of the magnetic flux density is higher in the hot final non-oriented silicon steel sheet of the present invention than in the comparative material.

Table 1 Test material components (wt%) C Si Mn P S Al N 0.0016 0.31 0.12 0.064 0.0017 0.0020 0.0017

[0026]

(Example 2) Steels having the components shown in Table 3 were melted and subjected to finish hot rolling. In the example of the present invention, the sheet bar after the rough rolling was continuously welded to the preceding sheet bar to perform finish hot rolling. On the other hand, in the comparative example, continuous hot rolling of the sheet bar was not performed. Finish plate thickness is 1.00mm and 900 ℃
This was wound at 860 ° C. as the first winding. Thereafter, the coil was kept at 830 ° C. for 30 minutes, unwound, cooled, and wound at 400 ° C.
Thereafter, the hot-rolled steel sheet was subjected to pickling. An Epstein sample was cut out from each of the leading, middle, and trailing ends of both coils, and the magnetic flux density was measured. Table 4 shows the measurement results of the magnetic flux density of the present invention and the comparative example. As is evident from Table 4, according to the present invention, it is possible to manufacture a non-oriented silicon steel sheet having a small variation in magnetic properties in the coil and excellent in magnetism.

Table 3 Test material components (wt%) C Si Mn P S Al N 0.0019 0.14 0.12 0.13 0.0019 0.0010 0.0015

[0029]

(Example 3) Steels having the components shown in Table 5 were melted to form slabs, which were subjected to finish hot rolling. Hot rolling finish temperature 90
The temperature was set to 0 ° C. and the thickness was 1.0 mm. At this time, the range of the finishing temperature derived from the above equation (1) is not less than 783 ° C. and not more than 1050 ° C. In this example, the winding was performed while changing the winding temperature, and the relationship with the magnetism was examined. The coil holding temperature after the first winding is 780 ° C,
After heating for 1 hour as necessary, the coil was unwound for cooling, followed by a second winding at 500 ° C. From this, we cut out the Epstein sample,
The value of B50, which is the excitation magnetic flux density in a magnetic field of 5000 A / m, was measured. Table 6 shows the results. From the results in Table 6,
It can be seen that by maintaining the first winding temperature within the range of Expression (1), a hot-rolled silicon steel sheet having high magnetic flux density and excellent magnetism can be manufactured.

Table 5 Components of test material (wt%) C Si Mn PS Al N 0.0016 0.30 0.12 0.075 0.0016 0.001 0.0015

Table 6 Measurement Results of Magnetic Flux Density Winding Temperature (° C.) Magnetic Flux Density B50 (T) Inventive Example 850 1.781 Inventive Example 832 1.780 Inventive Example 800 1.775 Comparative Example 760 1.765 Comparative Example 740 1.760

Example 4 Steels having the components shown in Table 7 were melted to form slabs, and hot-rolled for finishing. Hot rolling finishing temperature 1
The temperature was set to 000 ° C. and the plate thickness was finished to 1.0 mm. At this time, the range of the finishing temperature derived from equation (1) is 818 ° C. or more and 1050 ° C. or less. In this example, the winding was performed while changing the winding temperature, and the relationship with the magnetism was examined. The holding temperature of the coil after the first winding is 830 ° C.
After heating for 1 hour as necessary, the coil was unwound for cooling, followed by a second winding at 500 ° C. The coil after the hot rolling was pickled, an Epstein sample was cut out of the coil, and the value of B50, which was the excitation magnetic flux density in a magnetic field of 5000 A / m, was measured. Table 8 shows the results. From the results in Table 8, it is possible to manufacture a hot-rolled silicon steel sheet having a high magnetic flux density and excellent magnetism by maintaining the first winding temperature within the range of Expression (1).

Table 7 Test material components (wt%) C Si Mn PS Al N 0.0017 2.00 0.20 0.001 0.0017 0.20 0.0016

Table 8 Measurement Results of Magnetic Flux Density Winding Temperature (° C.) Magnetic Flux Density B50 (T) Inventive Example 855 1.725 Inventive Example 840 1.720 Comparative Example 800 1.698

(Example 5) A slab for a non-oriented silicon steel sheet having the components shown in Table 9 was heated by a usual method, formed into a coarse bar having a thickness of 30 mm by a rough rolling mill, and then subjected to tandem finishing heat of 7 stands. It was finished to 0.8 mm by rolling mill. On this occasion,
Hot rolling was performed while changing the rolling reduction of the final pass. At this time, the hot-rolling finishing temperature was set to 860 ° C. above 750 ° C. in the α-phase region below the Ar 1 point. In addition, the rolling reduction was set to less than 10% for the 5th and 6th stands which transformed to the α phase in the pass before the final pass. The steel sheet after finish hot rolling is once wound at 830 ° C.
After holding at 30 ° C. for 60 minutes, it was unwound and cooled again and wound up at 450 ° C. Then, it was pickled and cut into Epstein samples, and the magnetic properties were measured. Table 10
FIG. 11 also shows the reduction ratio of the final pass and the magnetic measurement results of the present invention and the comparative example. As described above, if at least one pass at the time of finish hot rolling has a rolling reduction of 10% or more in the α-phase region, a hot-rolled silicon steel sheet having a high magnetic flux density and a low iron loss value and excellent magnetic properties can be obtained. It is possible.

Table 9 Test material components (wt%) C Si Mn P S Al N 0.0017 0.30 0.12 0.070 0.0016 0.0001 0.0015

Table 10 Results of magnetic flux density measurement Finished hot-rolled final magnetic flux density B50 Iron loss W15 / 50 Pass rolling reduction (%) (T) (W / kg) Comparative Example 6 1.750 5.56 Inventive Examples 17 1. 770 5.36 Invention Example 25 1.771 5.24 Invention Example 35 1.775 5.23

(Example 6) A slab for non-oriented silicon steel having the components shown in Table 11 was heated by a usual method, and was finished into a coarse bar having a thickness of 30 mm by a rough rolling mill. Finished to 1.0 mm with a tandem hot rolling mill. At this time, hot rolling was performed while changing the rolling reduction of the final pass. At this time, the hot-rolling finishing temperature is in the range of α
The temperature was set to 860 ° C. which was 0 ° C. or higher. The steel sheet after the finish hot rolling was once wound at 830 ° C., held at 830 ° C. for 60 minutes, then unwound and cooled again, and wound at 450 ° C.
Then, it was pickled and cut into Epstein samples, and the magnetic properties were measured. Table 12 also shows the components of the present invention and comparative examples and the results of magnetic measurement. Thus, if at least one pass at the time of finishing hot rolling takes a rolling reduction of 10% or more in the α phase region,
It is possible to obtain a hot-rolled silicon steel sheet having a high magnetic flux density and excellent magnetic properties with a low iron loss value.

Table 11 Components of test material (wt%) C Si Mn PS Al Sn NB 0.0016 0.50 0.50 0.068 0.0016 0.20 0.050 0.0014 0.0015

Table 12 Results of Magnetic Flux Density Measurement Final Finished Hot Rolled Magnetic Flux Density B50 Iron Loss W15 / 50 Pass Reduction (%) (T) (W / kg) Comparative Example 8 1.730 4.54 Invention Example 19 745 4.26 Inventive Example 26 1.756 4.22 Inventive Example 36 1.760 4.11

Example 7 A slab for a non-oriented silicon steel sheet having the components shown in Table 9 was heated by a usual method, and finished into a coarse bar having a thickness of 30 mm by a rough rolling mill. Finished to 2.5 mm with a hot rolling mill. At this time, hot rolling was performed while changing the rolling reduction of the final pass. At this time, the hot-rolling finishing temperature was set to 860 ° C. in the α-phase region below the Ar 1 point and 750 ° C. or more. Also, the 5 and 6 stands that transform to the α phase in the pass before the final pass have a reduction rate of 10
%. The steel sheet after the finish hot rolling was once wound at 830 ° C., held at 830 ° C. for 60 minutes, then unwound and cooled again, and wound at 450 ° C. Thereafter, it was pickled and finished to 0.50 mm by cold rolling. This was annealed at 750 ° C. for 30 seconds in a continuous annealing furnace. afterwards,
Epstein samples were cut and the magnetic properties were measured. Table 1
FIG. 3 also shows the magnetic measurement results of the present invention and the comparative example. In this way, at least one pass during hot rolling in the finish is in the α phase
%, It is possible to obtain a hot-rolled silicon steel sheet having a high magnetic flux density and a low iron loss value and excellent magnetic properties.

Table 13 Results of Magnetic Flux Density Measurement Final Finished Hot Rolling Final Magnetic Flux Density B50 Iron Loss W15 / 50 Pass Reduction Ratio (%) (T) (W / kg) Comparative Example 6 1.750 5.56 Invention Example 17 770 5.36 Invention Example 25 1.771 5.24 Invention Example 35 1.775 5.23

(Example 8) A slab for a non-oriented silicon steel sheet having the components shown in Table 11 was heated by a usual method, finished to a rough bar of 30 mm thickness by a rough rolling mill, and then finished in tandem of 7 stands. Finished to 2.5 mm with a hot rolling mill. At this time, hot rolling was performed while changing the rolling reduction of the final pass. At this time, the hot-rolling finishing temperature was set to 860 ° C. in the α-phase region below the Ar 1 point and 750 ° C. or more. The steel sheet after the finish hot rolling was once wound at 830 ° C., held at 830 ° C. for 60 minutes, then unwound and cooled again, and wound at 450 ° C. After that, it is pickled and cold-rolled to a thickness of 0.5
Finished to 0mm. This is placed in a continuous annealing furnace at 800 ° C. for 30 minutes.
Annealed for seconds. Thereafter, it was cut into Epstein samples, and the magnetic properties were measured. Table 14 also shows the magnetic measurement results of the present invention and the comparative example. As described above, if at least one pass at the time of finish hot rolling has a rolling reduction of 10% or more in the α-phase region, a hot-rolled silicon steel sheet having a high magnetic flux density and a low iron loss value and excellent magnetic properties can be obtained. It is possible.

Table 14 Results of Measurement of Magnetic Flux Density Finished hot-rolled final magnetic flux density B50 Iron loss W15 / 50 Pass rolling reduction (%) (T) (W / kg) Comparative Example 8 1.730 4.54 Invention Example 19 745 4.26 Inventive Example 26 1.756 4.22 Inventive Example 36 1.760 4.11

(Example 9) A slab for a non-oriented silicon steel sheet having the components shown in Table 15 was heated by a usual method, and finished into a coarse bar having a thickness of 40 mm by a rough rolling mill. Finished to 2.0 mm. At this time, the hot rolling finishing temperature was 860 ° C. Wind it up with a proximity coiler,
It was covered with a heat insulating cover and kept at 830 ° C. for 1 hour. Thereafter, the coil was unwound, cooled, and wound at 450 ° C. On the other hand, in the comparative example, the hot rolling finish temperature and the retention time were the same, but the heat retention cover was not provided. Then, it was pickled and finished to a thickness of 0.50 mm by cold rolling.
This was annealed at 830 ° C. for 30 seconds in a continuous annealing furnace. Thereafter, the Epstein sample was cut from the top, middle, and rear ends of the product coil, and the magnetic properties were measured. Table 16 also shows the magnetic measurement results of the present invention and the comparative example. As is clear from Table 16, the use of the heat retaining cover makes it possible to obtain a hot-rolled silicon steel sheet having stable magnetism in the coil longitudinal direction and excellent magnetism.

Table 15 Test material components (wt%) C Si Mn P S Al N 0.0015 0.50 0.50 0.052 0.0019 0.20 0.0015

Table 16 Magnetic flux density measurement results of the present invention and a comparative example Sampling position Flux density B50 (T) Iron loss W15 / 50 (w / kg) Present invention example Coil top 1.788 3.56 Coil middle 1.789 3.56 coil rear end 1.789 3.59 comparative example coil head 1.730 4.49 coil middle 1.775 4.35 coil rear end 1.764 4.43

(Example 10) A slab for a non-oriented silicon steel sheet having the components shown in Table 17 was heated by a usual method, and finished into a coarse bar having a thickness of 40 mm by a rough rolling mill. Finished to 2.0 mm. At this time, the hot rolling finishing temperature was 860 ° C. This was wound up with a proximity coiler, covered with a heat insulating cover, and kept at 830 ° C. for 1 hour.
Thereafter, the coil is unwound and cooled to 450 ° C.
Rolled up. On the other hand, in the comparative example, the hot rolling finish temperature and the retention time were the same, but the heat retention cover was not provided. Then, it was pickled and finished to a thickness of 0.50 mm by cold rolling. This was annealed at 900 ° C. for 30 seconds in a continuous annealing furnace. Thereafter, the Epstein sample was cut from the top, middle, and rear ends of the product coil, and the magnetic properties were measured. Table 18 also shows the magnetic measurement results of the present invention and the comparative example. As described above, by using the heat retaining cover, it is possible to obtain a hot-rolled silicon steel sheet having stable magnetism in the coil longitudinal direction and excellent magnetism.

Table 17 Composition of test material (wt%) C Si Mn PS Al N 0.0015 2.00 0.22 0.002 0.0016 0.22 0.0015

Table 18 Magnetic flux density measurement results of the present invention and the comparative example Sampling position Magnetic flux density B50 (T) Iron loss W15 / 50 (w / kg) Present invention example Coil head 1.718 3.33 Coil middle 1.719 3.30 Coil rear end 1.719 3.29 Comparative example Coil head 1.680 3.49 Coil middle 1.715 3.35 Coil rear end 1.704 3.43

(Example 11) A slab for a non-oriented silicon steel sheet having the components shown in Table 19 was heated by a usual method, and was finished into a coarse bar having a thickness of 40 mm by a rough rolling mill. Finished to 2.0 mm. At this time, the hot rolling finishing temperature was 860 ° C. This was wound up with a proximity coiler, covered with a heat insulating cover, and kept at 830 ° C. for 1 hour.
Thereafter, the coil is unwound and cooled to 450 ° C.
Rolled up. On the other hand, in the comparative example, the hot rolling finish temperature and the retention time were the same, but the heat retention cover was not provided. Thereafter, it was pickled and cold rolled to a thickness of 0.50 mm. This was annealed at 950 ° C. for 30 seconds in a continuous annealing furnace. Thereafter, the Epstein sample was cut from the top, middle, and rear ends of the product coil, and the magnetic properties were measured. Table 20 also shows the magnetic measurement results of the present invention and the comparative example. As described above, by using the heat retaining cover, it is possible to obtain a hot-rolled silicon steel sheet having stable magnetism in the coil longitudinal direction and excellent magnetism.

Table 19 Test material components (wt%) C Si Mn PS Al N 0.0017 3.09 0.12 0.003 0.0015 1.01 0.0016

Table 20 Magnetic flux density measurement results of the present invention and a comparative example Sampling position Flux density B50 (T) Iron loss W15 / 50 (w / kg) Present invention example Coil top 1.676 2.18 Coil middle 1.675 2.20 Coil rear end 1.675 2.25 Comparative example Coil head 1.635 2.49 Coil middle 1.671 2.35 Coil rear end 1.668 2.43

(Example 12) Steels having the components shown in Table 5 were melted to form slabs, and finish hot rolling was performed. Hot rolling finishing temperature 9
The temperature was set to 00 ° C and the thickness was finished to 2.0 mm. At this time, the range of the finishing temperature derived from the above equation (1) is not less than 783 ° C. and not more than 1050 ° C. In this example, the winding was performed while changing the winding temperature, and the relationship with the magnetism was examined. Heating is performed as necessary so that the holding temperature of the coil after the first winding is 780 ° C., and after maintaining for 1 hour, the coil is unwound and cooled, and the second time at 500 ° C. Winding was performed. The coil after hot rolling is pickled, finished to a thickness of 0.50 mm by one cold rolling,
Recrystallization annealing for 0 seconds was performed. From this, an Epstein sample was cut out, and the value of the excitation magnetic flux density B50 at a magnetic field of 5000 A / m was measured. Table 21 shows the results.
From the results in Table 21, it is possible to manufacture a hot-rolled silicon steel sheet having a high magnetic flux density and excellent magnetism by maintaining the first winding temperature within the range of Expression (1).

Table 21 Measurement Results of Magnetic Flux Density Winding Temperature (° C.) Magnetic Flux Density B50 (T) Inventive Example 850 1.788 Inventive Example 832 1.786 Inventive Example 800 1.782 Comparative Example 760 1.771 Comparative Example 740 1.765

(Example 13) Steels having the components shown in Table 7 were melted to form slabs, which were subjected to finish hot rolling. Hot rolling finishing temperature 1
The temperature was set to 000 ° C. and the thickness was finished to 2.0 mm. At this time, the range of the finishing temperature derived from the above equation (1) is 818 ° C.
Not less than 1050 ° C. In this example, the winding was performed while changing the winding temperature, and the relationship with the magnetism was examined. Heating is performed as necessary so that the holding temperature of the coil after the first winding is 830 ° C., and after maintaining for 1 hour, the coil is unwound and cooled. Winding was performed. The coil after hot rolling was pickled and subjected to cold rolling to finish to a thickness of 0.50 mm. 95
Recrystallization annealing was performed at 0 ° C. for 30 seconds. From this, an Epstein sample was cut out, and the value of the excitation magnetic flux density B50 at a magnetic field of 5000 A / m was measured. Table 22 shows the results. From the results in Table 22, it is possible to manufacture a hot-rolled silicon steel sheet having a high magnetic flux density and excellent magnetism by maintaining the first winding temperature within the range of Expression (1).

Table 22 Measurement Results of Magnetic Flux Density Winding Temperature (° C.) Magnetic Flux Density B50 (T) Inventive Example 855 1.734 Inventive Example 840 1.728 Comparative Example 800 1.705

[0059]

As described above, according to the present invention, it is possible to produce a hot-rolled silicon steel sheet having high magnetic flux density, low iron loss and excellent magnetism.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takehide Senuma 1-1 Futaba-cho, Tobata-ku, Kitakyushu Nippon Steel Corporation Yawata Works F-term (reference) 4K033 AA01 CA02 CA06 CA08 CA09 FA03 FA04 FA10 FA11 5E041 AA11 AA19 CA04 HB00 HB07 HB11 NN01 NN17 NN18

Claims (8)

[Claims] 1.% by weight: 0.1% ≦ Si ≦ 4%, 0.1% ≦ Mn ≦ 1.5%, C ≦ 0.05%, N ≦ 0.01%, P ≦ 0.15 %, The steel comprising the balance of Fe and unavoidable impurities is hot-rolled to produce a silicon steel sheet. After the finish hot rolling, the first winding temperature is set to 750 ° C. or more and 1050 ° C. or less, and once wound, A method for producing a hot-rolled silicon steel sheet excellent in magnetism, comprising: holding for 30 seconds to 90 minutes, rewinding, cooling, and rewinding at a temperature of 550 ° C. or less. 2. The hot rolling excellent in magnetism according to claim 1, wherein the lower limit of the first winding temperature is defined as X defined by the following equation (1) by the hot rolling end temperature FT. Manufacturing method of silicon steel sheet. X = 0.67 × FT−20 × FT ^0.5 +780 (1) 3. In the finish hot rolling, at least one pass in the α phase region is reduced by 10% or more, and the hot rolling end temperature is reduced to 75%.
The method for producing a hot-rolled silicon steel sheet excellent in magnetism according to claim 1 or 2, wherein the temperature is 0 ° C or higher and the Ar1 point or lower. 4. The production of a hot-rolled silicon steel sheet excellent in magnetism according to claim 1, further comprising using steel containing 0.1 to 2.5% of Al. Method. 5. The production of a hot-rolled silicon steel sheet excellent in magnetism according to any one of claims 1 to 4, wherein a steel containing 1.5 or less of B in B / N is used. Method. 6. The method for producing a hot-rolled silicon steel sheet having excellent magnetism according to claim 1, further comprising using steel containing 0.1% or less of Sn. 7. The sheet bar after rough rolling is subjected to hot rolling before finishing.
The hot-rolled silicon steel sheet excellent in magnetism according to any one of claims 1 to 6, wherein the hot-rolled silicon steel sheet is bonded to a preceding sheet bar and the connected sheet bar is continuously subjected to finish hot rolling. Production method. 8. A magnetic material comprising using a hot-rolled silicon steel sheet produced by the method according to claim 1, further performing pickling and cold rolling, and then performing recrystallization annealing. Method for manufacturing non-oriented electrical steel sheet with excellent properties.