JPH1046246A - Manufacture of nonoriented magnetic steel sheet with high magnetic flux density - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacture of a nonoriented silicon steel sheet advantageous to the miniaturization of iron core and having high magnetic flux density. SOLUTION: This nonoriented silicon steel sheet can be produced by hot- rolling a steel having a composition consisting of, by weight, >0.10-4.00% Si, 0.1-1.0% Mn, 0.10-2.00% Al, <=0.0050% C, <=0.0050% N, <=0.0050% S, and the balance Fe with inevitable impurities, subjecting the resultant hot rolled plate to hot rolled plate annealing, performing a single cold rolling, stage, and then applying finish annealing or applying skin pass rolling after finish annealing to the resultant cold rolled sheet. In this case, at the time of finish hot rolling, finish hot rolling is carried out under the conditions of >=150s<-1> strain rate at least one pass and >=1.5kgf/mm<2> tension between at least a set of stands, and moreover, cold rolling rate is regulated to <=75%. Further, roughed sheet bars are joined by hot rolling and subjected, continuously, to finish hot rolling.

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 non-oriented electrical steel sheet having a high magnetic flux density, which is used as a core material of electric equipment.

[0002]

2. Description of the Related Art In recent years, in the fields of electric machines, especially rotating machines and medium-sized and small-sized transformers in which non-oriented electrical steel sheets are used as iron core materials, worldwide electric power and energy savings, as well as chlorofluorocarbon gas regulations. Among the movements for global environmental conservation, such as the above, the movement for higher efficiency is rapidly spreading. Therefore, there is an increasing demand for non-oriented electrical steel sheets to have improved properties, that is, high magnetic flux density and low iron loss. By the way, in the non-oriented electrical steel sheet, conventionally, as a means of reducing iron loss, a method of increasing the content of Si or Al or the like has been generally adopted from the viewpoint of reducing eddy current loss due to an increase in electric resistance. However, in this method, on the other hand, there is a problem that a decrease in magnetic flux density cannot be avoided. 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.

For this reason, after the finish hot rolling, hot strip annealing by box annealing or continuous annealing has been performed. As a technique for inexpensively coarsening the crystal structure before cold rolling of such a non-oriented electrical steel sheet, a hot rolled sheet after finish hot rolling is used.
Japanese Patent Application Laid-Open No. 54-76422 discloses a self-annealing method of winding at a high temperature of 0 ° C. to 1000 ° C. and annealing the coil by the retained heat of the coil. A method is disclosed in which a non-water injection time is set as a high temperature of 1000 ° C. or more, and a hot-rolled structure is recrystallized and grown on a so-called run-out table before winding.

Further, as a technique for improving the magnetic characteristics of a high-grade non-oriented electrical steel sheet having a high Si-based component in which recrystallization and grain growth progress slowly, by controlling hot rolling, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 74222/1990 discloses a technique in which the rolling reduction temperature of a hot-rolled sheet is set to 700 ° C. or higher by setting the rolling reduction of the final hot-rolling final stand to 20% or more. In this case,
The aim is to increase the final stand draft and raise the winding temperature to promote the recrystallization and grain growth of the hot-rolled structure after the hot-rolling, and as a result, to improve the magnetic properties. However, when the Si content in the steel sheet is high, although recrystallization of the hot-rolled sheet is promoted by this technique, the subsequent grain growth is insufficient, and the improvement of the magnetic flux density is insufficient.

On the other hand, as a technique for increasing the magnetic flux density by using the hot rolled sheet annealing together with the iron loss reduction, a steel having a Si content of 2.5% to 4.0% is disclosed in
No. 9-74258 discloses that S ≦ 15 ppm, O ≦ 20p
JP-A-59-74257 discloses a method of producing high-purity steel having a pm and N ≦ 25 ppm.
0 ppm, N ≦ 25 ppm and Ti + Zr + Ce +
Japanese Patent Application Laid-Open No. 59-742 discloses a method of setting Ca ≦ 150 ppm.
No. 23 discloses S ≦ 15 ppm, O ≦ 20 ppm, N ≦
In addition to 25 ppm, the rate of temperature rise during finish annealing is 300 ° C / S
The technique described above is disclosed in Japanese Patent Application Laid-Open No. Sho 59-74224, where S ≦ 15 ppm, O ≦ 20 ppm,
Japanese Patent Application Laid-Open No. 59-74225 discloses a technique for defining the annealing conditions for hot-rolled sheets and defining the cold-rolling rate to be 65% or more in addition to the regulation of N ≦ 25 ppm. ≦ 15ppm, O ≦ 20ppm, N ≦ 25ppm
In addition to the above, there are disclosed techniques for defining intermediate annealing conditions and defining a second cold rolling reduction of 70% or more.

With respect to the high magnetic flux density and low iron loss non-oriented electrical steel sheets provided by the prior art, consumers have demanded a higher magnetic flux density to reduce the size of the core of the rotating machine and improve the efficiency. There has been a strong demand for the provision of non-oriented electrical steel sheets. The inventors paid attention to the finishing hot-rolling technology in order to find a way to meet the demands of consumers for such non-oriented electrical steel sheets, and studied. In the finishing hot rolling of non-oriented electrical steel sheets, higher precision of the product thickness is required as compared with thin steel sheets which are subjected to press forming of outer plates of automobiles and deep drawing of cans and the like. This is because the non-oriented electrical steel sheet is used as being laminated as an iron core, so that a slight deviation in the product thickness greatly affects the dimensional accuracy of the iron core.

For this reason, strict control is required for the thickness accuracy of the product. For this purpose, strict control of the thickness is performed not only for cold rolling but also for hot rolling. Therefore, in the vicinity of the final pass of the finishing hot rolling, the rolling reduction is reduced to a light reduction for shape adjustment, and the strain rate is usually small.Therefore, there is no attempt to examine the conditions of the finishing hot rolling from the viewpoint of improving magnetic properties. Traditionally hardly ever. Further, when the cold rolling reduction is reduced, there is less room for correcting the thickness non-uniformity of the hot-rolled sheet, and the unevenness of the shape such as the crown in the sheet width direction by cold rolling. No consideration was given to controlling the cold rolling reduction in relation to the speed or the like.

[0008] The inventors reviewed the concept of the prior art regarding the management of operating conditions for hot rolling and cold rolling, and examined the conditions from the viewpoint of improving the magnetic properties of the product. In the non-oriented electrical steel sheet manufacturing process of performing annealing, or in the non-oriented electrical steel sheet manufacturing process of performing self-annealing, first, at the time of finish hot rolling, by increasing the strain rate and tension in at least one pass, Second, the magnetic flux density of the product increases.
By increasing the tension between at least one set of stands, it is possible to solve the problem that the magnetic flux density of the product increases and the thickness accuracy of the hot-rolled sheet decreases under high strain rate deformation.
Third, the magnetic flux density is improved by lowering the cold rolling reduction in a material that adopts the first and second hot rolling conditions. Fourth, the sheet bar after the rough rolling is removed before the finish hot rolling. By joining the preceding sheet bar and continuously subjecting the sheet bar to finish hot rolling, it was found that finishing hot rolling under a high strain rate and high tension can be stably performed, and the like. Reached.

[0009]

SUMMARY OF THE INVENTION The present invention addresses the strong demands of customers for high magnetic flux density and low iron loss on the magnetic characteristics of such non-oriented electrical steel sheets, and provides a high magnetic flux which is advantageous for downsizing the iron core. It is intended to provide a method for producing a non-oriented electrical steel sheet.

[0010]

The gist of the present invention is as follows. (1) 0.10% <Si ≦ 4.00% 0.10% ≦ Mn ≦ 1.00% C ≦ 0.0050% N ≦ 0.0050% S ≦ 0.0050% by weight% in steel A non-directional electromagnetic steel containing a slab containing Fe and inevitable impurities, hot-rolled into a hot-rolled sheet, subjected to hot-rolled sheet annealing, cold-rolled once, and then finish-annealed. In the method for manufacturing a steel sheet, at the time of finishing hot rolling, at least one pass has a strain rate of 150 s ^-1 or more and a tension between at least one set of stands is 1.5 kgf.
/ Mm ² or more, hot rolling is performed, and the cold rolling rate is 75
% Or less, a method for producing a non-oriented electrical steel sheet having a high magnetic flux density.

(2) By weight% in steel, 0.10% ≦
The method for producing a non-oriented electrical steel sheet having a high magnetic flux density according to the above (1), characterized by containing Al ≦ 2.00%. (3) 850 ° C or higher and 1100 ° C for hot rolled sheet after finishing hot rolling
The method for producing a non-oriented electrical steel sheet having a high magnetic flux density according to the above (1) or (2), wherein continuous annealing is performed at the following temperature for 20 seconds or more and 5 minutes or less. (4) The magnetic flux density according to (1) or (2), wherein the hot-rolled sheet after the finish hot-rolling is subjected to box annealing for 5 minutes to 30 hours at a temperature of 700 ° C to 850 ° C. Method for manufacturing non-oriented electrical steel sheets with high quality.

(5) The hot rolled sheet after the finish hot rolling is wound at a temperature of 750 ° C. or more and 1050 ° C. or less, and self-annealed by the heat retained by the coil itself for 5 minutes to 5 hours. The method for producing a non-oriented electrical steel sheet having a high magnetic flux density according to (1) or (2). (6) After the first cold rolling, a finish annealing is performed, and further a skin pass rolling of 2% or more and 20% or less is performed (1).
(5) The method for producing a non-oriented electrical steel sheet having a high magnetic flux density according to (5). (7) The sheet bar according to any one of (1) to (6), wherein the sheet bar after the rough rolling is joined to a preceding sheet bar before the finish hot rolling, and the sheet bar is continuously subjected to the finish hot rolling. A method for manufacturing non-oriented electrical steel sheets with high magnetic flux density.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The magnetic properties of the non-oriented electrical steel sheet can be improved by increasing the crystal structure before cold rolling. Conventionally, in non-oriented electrical steel sheets, after hot-rolling, it has been generally performed to perform hot-rolled sheet annealing in a continuous annealing furnace or box annealing furnace to increase the crystal structure before cold rolling. However, at present, there is a demand from recent consumers for the supply of non-oriented electrical steel sheets having even better magnetic properties. In addition, in the conventional technology, in order to reduce the manufacturing cost of high magnetic flux density non-oriented electrical steel sheets, in the process of performing cold rolling and annealing without performing hot rolled sheet annealing, recrystallization and grain growth after completion of hot rolling are promoted. For this purpose, the hot rolling end temperature had to be kept high, and the slab heating temperature had to be raised. Raising the slab heating temperature, however, requires Mn during heating.
It promotes re-solid solution of precipitates such as S and AlN in steel, and this precipitates finely at the time of hot rolling, which hinders the growth of crystal grains at the time of hot-rolled sheet annealing and finish annealing, and deteriorates iron loss. There were challenges.

The inventors of the present invention focused on hot rolling of non-oriented electrical steel sheets to overcome such limitations of the prior art, and as a result, found that Si exceeded 0.10% and was 4.00% or less. 0.10% or more and 1.00% or less;
In a steel containing 10% or more and 2.00% or less, at the time of finish hot rolling, in at least one pass, the strain rate is increased, and the tension between at least one set of stands is also increased to produce a hot-rolled sheet; By cold rolling this at a specific rolling reduction, it has been found that a non-oriented electrical steel sheet having a high magnetic flux density in a product can be manufactured. Further, in order to stably perform finishing hot rolling under a high strain rate and high tension as in the present invention, the sheet bar after the rough rolling is joined to the preceding sheet bar, and the finishing hot rolling is continuously performed. It was also found that it was effective to do it in a holistic way.

First, the components will be described. Si is added to increase the specific resistance of the steel sheet, reduce the eddy current loss, and improve the iron loss value. If the Si content is 0.10% or less, the specific resistance required for the low iron loss non-oriented electrical steel sheet aimed at by the present invention cannot be sufficiently obtained, so it is necessary to add an amount exceeding 0.10%. is there. On the other hand, the Si content is 4.
If it exceeds 00%, ear cracks during rolling increase remarkably, and rolling becomes difficult. Therefore, it is necessary to be 4.00% or less. A
1 also has the effect of increasing the specific resistance of the steel sheet and reducing the eddy current loss, similarly to Si. In order to obtain a low iron loss high magnetic flux density non-oriented electrical steel sheet intended by the present invention, 0.1
It is necessary to add 0% or more. On the other hand, when the Al content is 2.
If it exceeds 00%, the magnetic flux density decreases and the cost increases, so it is set to 2.00% or less. Further, even if the Al content in the steel is less than 0.10%, the effect of the present invention is not impaired at all.

Mn, like Al and Si, has the effect of increasing the specific resistance of a steel sheet and reducing eddy current loss. For this purpose, the Mn content needs to be 0.10% or more. On the other hand, if the Mn content exceeds 1.00%, the deformation resistance during hot rolling increases and hot rolling becomes difficult, and the crystal structure after hot rolling tends to become finer, which deteriorates the magnetic properties of the product. The Mn content needs to be 1.00% or less. Further, the amount of Mn addition is extremely important from the viewpoint of securing the strength of the high temperature sheet bar joint before the hot rolling.
The reason for this is that in order to prevent hot embrittlement of the sheet bar joint due to the presence of the low-melting sulfide at the crystal grain boundaries, M
This is because it is necessary to set the value of Mn / S, which is the ratio of the weight concentrations of n and S, to 20 or more. In the component range defined in the present invention, since the Mn content is 0.1% or more and the S content is 0.0050% or less, the value of Mn / S is maintained at 20 or more. there is no problem.

In order to improve the mechanical properties, magnetic properties, and rust resistance of the product or for other purposes, P,
Even if one or more of B, Ni, Cr, Sb, Sn, and Cu are contained in steel, the effect of the present invention is not impaired.
When the C content exceeds 0.0050%, iron loss is deteriorated due to magnetic aging during use and energy loss during use is increased. Therefore, it is necessary to control the content to 0.0050% or less. S and N partially re-dissolve during slab heating in the hot rolling step, and form sulfides such as MnS and nitrides such as AlN during hot rolling. The presence of these elements hinders the grain growth of the hot-rolled structure and hinders the crystal grain growth during the finish annealing, resulting in deterioration of iron loss. Therefore, S must be 0.0050% or less and N must be 0.0050% or less.

Next, the process conditions of the present invention will be described. The following experiment was conducted to investigate the influence of the strain rate of the pass during finishing hot rolling and the tension between stands on the product magnetic properties. Steel having the components shown in Table 1 was melted and subjected to finish hot rolling. The test was performed by changing the pass schedule in order to change the strain rate of the final pass at the time of finishing hot rolling and the tension between stands of the final two passes. Finish hot rolling end temperature is 900 ° C.
After finishing to a thickness of 5 mm and cooling with water, the film was wound at 650 ° C. Thereafter, steel A was heated at 850 ° C. for 2 minutes and steel B was heated at 950 ° C. in a continuous annealing furnace.
The sheet was annealed at 2 ° C. for 2 minutes. This is pickled and cold rolled.
After degreasing to a thickness of 50 mm, steel A was annealed at 750 ° C. for 30 seconds, and steel B was annealed at 950 ° C. for 30 seconds, and the Epstein sample was cut to measure magnetic properties.

[0019]

[Table 1]

FIG. 1 shows the dependence of the product magnetic flux density on the strain rate of the final pass during hot rolling in finishing. At this time, the tension between the last two stands was 3.3 kgf / mm ² . FIG.
According to the figure, it is understood that the product magnetic flux density increases at a strain rate of 150 s ^-1 or more. The calculation of the strain rate is performed by the following equation. Here, r is the rolling reduction% / 100, n is the number of rotations of the roll (rpm), R is the rolling roll radius (mm),
H ₀ is the thickness (mm) before rolling. Strain rate = [2πn / (60r ^0.5 )] (R / H ₀ )
^0.5 ln [1 / (1-r)] Next, the final stand strain rate of the hot-rolled finish was set to 325 s ⁻¹ , and the tension was changed between the last two stands. FIG. 2 shows the relationship between the tension between the last two stands and the magnetic flux density of the product during hot rolling. As shown in FIG. 2, the tension between the last two stands of the finish hot rolling is 1.5 k.
It can be seen that the product magnetic flux density increases with gf / mm ² or more.

Next, the following experiment was conducted to investigate the effect of the cold rolling reduction on the magnetic properties. Steel B was hot rolled at a finish hot rolling end temperature of 900 ° C. with a different thickness of the finished plate, cooled with water and wound at 650 ° C. At this time, the strain rate of the last pass was 320 s ⁻¹ , and the tension between the last two stands was 3.3 kgf /
It was mm ^2. Thereafter, hot rolled sheet annealing was performed at 950 ° C. for 2 minutes using a continuous annealing furnace. This is pickled and cold rolled to 0.50 mm
After degreasing, the sample was annealed at 950 ° C. for 30 seconds, and the Epstein sample was cut to measure magnetic properties. FIG. 3 shows the dependence of the magnetic flux density on the cold rolling reduction. FIG. 3 shows that the product magnetic flux density increases when the cold rolling reduction is 75% or less.

As shown in the above experiments, the strain rate of at least one pass in the finish hot rolling is 150 s ^-1 or more, and the tension between at least one set of stands is 1.5 kgf.
/ Mm ² or more, and the cold rolling reduction may be 75% or less.
There is no particular upper limit on the strain rate. This is because the upper limit of the strain rate is naturally determined from the equipment capacity of the hot rolling mill and the shape controllability of the hot rolled sheet. That is, the strain rate is determined by the rolling speed, hot-roll roll diameter, the amount of reduction, rolling speed,
Increasing the rolling reduction increases the strain rate, but makes it difficult to control the shape of the hot-rolled steel sheet. Since non-oriented electrical steel sheets are used in a laminated state, strict control is required for their shapes, and there is naturally a limit in increasing the strain rate. From this viewpoint, the strain rate is 600 s ^-1.
Degree is the limit.

There is no upper limit on the tension between the last two stands. However, if the tension between the stands becomes large, deformation occurs at the time of passing the plate, and the plate width becomes narrow. Therefore, it is necessary to increase the slab width to compensate for this. is there. The limit of the tension from this viewpoint is about 10 kgf / mm ² . Further, in order to stably perform finishing hot rolling under a high strain rate and high tension as in the present invention, the sheet bar after the rough rolling is joined to the preceding sheet bar, and the finishing hot rolling is continuously performed. This is particularly effective. The steel slab composed of the above components is produced by melting in a converter and being manufactured by continuous casting or ingot-bulking rolling. The steel slab is heated by a known method. This slab is subjected to hot rolling to a predetermined thickness.

In the present invention, the hot rolled sheet after finishing hot rolling is promoted by any of continuous annealing, box annealing and self-annealing to promote crystal grain growth to improve the magnetic properties of the product. In the case of continuous annealing,
The hot-rolled sheet annealing temperature is 1100 ° C. or less. If the hot-rolled sheet annealing temperature exceeds 1100 ° C., even if the atmosphere is carefully controlled, oxidation of the steel sheet cannot be prevented, and the iron loss of the product is significantly deteriorated. Therefore, in the case of continuous annealing, the hot-rolled sheet annealing temperature is set to 1100 ° C. or less. 850 ° C
If it is less than 850 ° C., the crystal grain growth becomes insufficient, so the temperature is set to 850 ° C. or more. The hot-rolled sheet annealing time is set to 20 seconds or more and 5 minutes or less in continuous annealing. If the annealing time is less than 20 seconds, the improvement of the magnetic properties is insufficient, and if it exceeds 5 minutes, the effect is saturated and it becomes uneconomical.

In the case of hot-rolled sheet annealing by box annealing, if the temperature is lower than 700 ° C., crystal grain growth becomes insufficient.
700 ° C or higher. If the temperature is higher than 850 ° C., the equipment of the box annealing furnace becomes extremely expensive and the improvement of the magnetic properties is saturated. The hot-rolled sheet annealing time is 5 minutes or more and 30 hours or less in box annealing, and preferably 1 hour.
It is longer than or equal to 20 hours. If the heating time is less than 5 minutes, the effect of annealing is insufficient. If the heating time is more than 30 hours, the deformation due to the weight of the coil generated during the high-temperature annealing becomes severe, and the yield is remarkably reduced.

In the present invention, self-annealing, in which hot-rolled sheet annealing is performed using the heat retained by the coil itself after finish annealing, is also effective. At that time, if the coiling temperature of the hot-rolled coil is lower than 750 ° C., the crystal grain growth during the self-annealing becomes insufficient, and the improvement of the magnetic properties is insufficient. On the other hand, when the winding temperature is higher than 1050 ° C., oxidation of the steel sheet during the high-temperature self-annealing cannot be prevented, and the iron loss of the product is remarkably deteriorated. Therefore, in the case of self-annealing, the winding temperature is 1050 ° C.
Determined below.

The self-annealing time is from 5 minutes to 5 hours, preferably from 30 minutes to 3 hours. If it is less than 5 minutes, the effect of annealing is insufficient, and if it exceeds 5 hours, the iron loss of the product is significantly deteriorated due to oxidation of the steel sheet. The hot-rolled sheet obtained by performing the hot-rolled sheet annealing in this manner is made into a product by one cold rolling and continuous annealing. Further, a product may be obtained by further adding skin pass rolling. If the skin pass rolling ratio is less than 2%, the effect cannot be obtained, and 20%
If it is more than 2%, the magnetic properties deteriorate, so the content is set to 2% to 20%.

[0028]

Next, an embodiment of the present invention will be described. (Example 1) Non-oriented electrical steel having the components shown in Table 2
The slab for heating by the usual method,
Finished to a 50 mm coarse bar, then
It was finished to 1.8 mm. Strain speed of final pass of finishing hot rolling
300-320s over the entire length of the coil^-1To control
Was. In addition, during finishing hot rolling, a gap
Prevents lip formation and flaw formation on steel sheet surface
In order to achieve this, the sheet bar after rough rolling
And finish hot rolling was continuously performed. This time,
The hot rolling finishing temperature was 900 ° C. After hot rolling, continuous annealing furnace
At 850 ° C. for 2 minutes. Then the acid
It was washed and finished to 0.50 mm by cold rolling. This
This was annealed at 750 ° C. for 30 seconds in a continuous annealing furnace. That
After that, cut into Epstein samples and measure the magnetic properties.
Was. Table 3 shows the components of the present invention and the comparative examples and the results of magnetic measurement.
I will show you. Thus, between the last two stands during finishing hot rolling
1.5kgf / mm^TwoBy raising it above
High magnetic flux density and low core loss
It is possible to obtain a non-oriented electrical steel sheet. Also,
The tension between the last two stands is 1.5kgf / mm^TwoBelow
In the comparative example, 20 mm from the edge of the hot rolled sheet and the center
The average of the total coil length of the sheet thickness deviation between
The tension between the last two stands is 1.5kgf
/ Mm ^TwoIn the examples of the present invention as described above, the
Settle down and control the tension between the last two stands
As a result, the thickness accuracy of the hot-rolled sheet was improved.

[0029]

[Table 2]

[0030]

[Table 3]

(Example 2)
Heat the slab for grain-oriented electrical steel in the usual way
Machine to make a 50mm thick rough bar, then finish
And finished to 1.7 mm with a hot rolling mill. Finish hot rolling final
3.0 kgf / mm tension between two stands ^TwoFrom 3.2
kgf / mm^TwoAnd rolled. Also, finish hot
During rolling, slip occurs between the steel sheet and the work roll
After rough rolling to prevent flaws from forming on the surface
Sheet bar to the preceding sheet bar and finish hot
Rolling was performed continuously. At this time, the hot rolling finish temperature is 90
The temperature was adjusted to 0 ° C, immediately cooled with water, and wound at 650 ° C. So
After that, hot rolled sheet annealing was performed at 950 ° C for 2 minutes using a continuous annealing furnace.
And then pickled and finished to 0.50mm by cold rolling
Was. This is annealed at 940 ° C. for 30 seconds in a continuous annealing furnace.
Was. After that, it is cut into Epstein samples and the magnetic properties are measured.
Specified. Table 5 shows the components and magnetic measurement results of the present invention and comparative examples.
Also shown. Thus, the distortion of the final pass during finishing hot rolling
150s speed^-1If it is increased above, the value of magnetic flux density will be high
And non-oriented electrical steel sheets with excellent magnetic properties and low iron loss
It is possible to get.

[0032]

[Table 4]

[0033]

[Table 5]

(Example 3) A sample having the components shown in Table 6
Heat the slab for grain-oriented electrical steel in the usual way
Machine to make a 50mm thick rough bar, then finish
And finished to 1.5 mm with a hot rolling mill. Finish hot rolling final
3.1 kgf / mm tension between two stands ^TwoFrom 3.3
kgf / mm^TwoAnd rolled. Also, finish hot
Strip occurs between the steel sheet and the work roll during rolling and the surface of the steel sheet
In order to prevent the formation of flaws in the
Weld the heat bar to the preceding sheet bar and finish hot roll
Was performed continuously. At this time, hot rolling finish temperature is 900 ℃
And immediately cooled with water and wound up at 650 ° C. That
Then, hot rolled sheet annealing was performed at 980 ° C for 2 minutes using a continuous annealing furnace.
And then pickled and finished to 0.50mm by cold rolling
Was. This is annealed at 950 ° C. for 30 seconds in a continuous annealing furnace.
Was. After that, it is cut into Epstein samples and the magnetic properties are measured.
Specified. Table 7 shows the components and magnetic measurement results of the present invention and comparative examples.
Also shown. Thus, the distortion of the final pass during finishing hot rolling
150s speed^-1If it is increased above, the value of magnetic flux density will be high
And non-oriented electrical steel sheets with excellent magnetic properties and low iron loss
It is possible to get.

[0035]

[Table 6]

[0036]

[Table 7]

(Example 4)
Heat the slab for grain-oriented electrical steel in the usual way
Machine to make a 50mm thick rough bar, then finish
And finished to 1.7 mm with a hot rolling mill. Finish hot rolling final
The tension between the two stands is 2.5kgf / mm ^TwoFrom 2.7
kgf / mm^TwoAnd rolled. Also, finish hot
Strip occurs between the steel sheet and the work roll during rolling
Rough rolling to prevent flaws from being formed on the surface of
The subsequent sheet bar is welded to the preceding sheet bar to finish heat
Cold rolling was performed continuously. At this time, the hot rolling finish temperature was 9
The temperature was adjusted to 50 ° C, immediately cooled with water, and wound at 650 ° C.
Thereafter, hot rolled sheet annealing at 800 ° C. for 5 hours was performed in a box annealing furnace.
, Pickling, cold rolling to a finish of 0.50mm
I got it. This is annealed at 800 ° C. for 30 seconds in a continuous annealing furnace.
Was. Then, cut into Epstein samples, 750 ° C for 2 hours
Between the annealing of the customer and the magnetic properties
It was measured. Table 9 shows the components and magnetic measurement results of the present invention and comparative examples.
Are also shown. In this way, the final pass at the time of finishing hot rolling
150s strain rate^-1If it is raised above, the value of magnetic flux density
Non-oriented electrical steel sheet with high magnetic properties and low iron loss
It is possible to obtain

[0038]

[Table 8]

[0039]

[Table 9]

Example 5 A slab for non-oriented electromagnetic steel having the components shown in Table 10 was heated by a conventional method, and finished into a 50 mm-thick coarse bar by a rough rolling mill. To 1.9 mm. The tension between the last two stands of the finishing hot rolling mill was kept constant at 2.9 kgf / mm ² . At this time, the hot rolling finishing temperature was 950 ° C.
The coil was wound at 0 ° C., the coil was placed in a heat retaining cover, and self-annealing was performed at 830 ° C. for 1 hour by the heat retained by the coil itself. Then, it was pickled, finished to 0.50 mm by cold rolling, and annealed at 850 ° C. for 2 minutes in a continuous annealing furnace. Thereafter, the specimen was cut into Epstein samples, and subjected to strain relief annealing corresponding to customer annealing at 750 ° C. for 2 hours, and the magnetic properties were measured. Table 11 also shows the components of the present invention and comparative examples and the results of magnetic measurement. By increasing the strain rate of the final pass at the time of finishing hot rolling to 150 s ^-1 or more, it is possible to obtain a non-oriented electrical steel sheet having a high magnetic flux density and an excellent magnetic property with a low iron loss value. .

[0041]

[Table 10]

[0042]

[Table 11]

[0043]

As described above, according to the present invention, it is possible to manufacture a non-oriented electrical steel sheet having a high magnetic flux density.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the strain rate of the final pass during finish hot rolling and the product magnetic flux density;

FIG. 2 is a diagram showing the relationship between the tension between the last two stands during final hot rolling and the magnetic flux density of a product;

FIG. 3 is a diagram showing a relationship between a cold rolling reduction and a magnetic flux density.

Claims (7)

[Claims] 1. 0.10% <Si ≦ 4.00% 0.10% ≦ Mn ≦ 1.00% C ≦ 0.0050% N ≦ 0.0050% S ≦ 0.0050% by weight in steel %, With the balance being Fe and inevitable impurities, hot-rolled into a hot-rolled sheet, subjected to hot-rolled sheet annealing, cold-rolled once, and then subjected to finish annealing. In the method for producing a conductive electrical steel sheet, at the time of finishing hot rolling, at least one pass has a strain rate of 150 s ^-1 or more and a tension between at least one set of stands is 1.5 kgf.
/ Mm ² or more, hot rolling is performed, and the cold rolling rate is 75
% Or less, a method for producing a non-oriented electrical steel sheet having a high magnetic flux density. 2. The composition according to claim 1, wherein the weight percentage in steel is 0.10% ≦ Al
The method for producing a non-oriented electrical steel sheet having a high magnetic flux density according to claim 1, characterized by containing ≤ 2.00%. 3. The hot-rolled sheet after finishing hot-rolling has a temperature of 850 ° C. or higher.
The method for producing a non-oriented electrical steel sheet having a high magnetic flux density according to claim 1 or 2, wherein the hot-rolled sheet is subjected to continuous annealing at a temperature of 100 ° C or less for 20 seconds or more and 5 minutes or less. 4. The hot-rolled sheet after finishing hot-rolling is subjected to box-roll annealing at a temperature of 700 ° C. to 850 ° C. for 5 minutes to 30 hours. 2. The method for producing a non-oriented electrical steel sheet having a high magnetic flux density according to 2. 5. The hot rolled sheet after the finish hot rolling is 750 ° C. or higher.
3. The non-directional sheet having a high magnetic flux density according to claim 1, wherein the coil is wound at a temperature of 050 [deg.] C. or less, and the hot rolled sheet is annealed by self-annealing with the heat of the coil itself for 5 minutes to 5 hours. Manufacturing method of electrical steel sheet. 6. The non-directional electromagnetic member having a high magnetic flux density according to claim 1, wherein after the first cold rolling, finish annealing is performed, and further, skin pass rolling of 2% or more and 20% or less is performed. Steel plate manufacturing method. 7. The magnetic flux according to claim 1, wherein the sheet bar after the rough rolling is joined to a preceding sheet bar before the hot rolling, and the sheet bar is continuously subjected to the hot rolling. A method for manufacturing non-oriented electrical steel sheets with high density.