JP2818290B2 - Method for producing grain-oriented silicon steel sheet with excellent magnetic properties - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a grain-oriented silicon steel sheet having excellent magnetic properties, and particularly to improving productivity and improving magnetic properties by improving the cold rolling process. They try to improve.

BACKGROUND ART Grain-oriented silicon steel sheets are required to have high magnetic flux density and low iron loss as magnetic properties. In recent years, with the development of manufacturing technology, for example, a steel plate with a thickness of 0.23 mm,
Magnetic flux density B ₈ (value at 800 A / m of magnetizing force): 1.92 T is obtained, and iron loss characteristic W _17/50 (value at the time of maximum magnetization of 1.7 T at 50 hz) is 0.90 W / kg. The production of excellent products on an industrial scale is also possible.

The material having such excellent magnetic properties is composed of a crystal structure in which the <001> orientation, which is the axis of easy magnetization of iron, is highly aligned with the rolling direction of the steel sheet. In the manufacturing process of a silicon steel sheet, it is formed through a phenomenon called secondary recrystallization in which crystal grains having a (110) [001] orientation so-called Goss orientation are preferentially giganticly grown during final annealing. . Basic requirements for sufficiently growing the (110) [001] secondary recrystallized grains include a crystal grain having an undesired orientation other than the (110) [001] orientation in the secondary recrystallization process. It is a well-known fact that the existence of an inhibitor that inhibits the growth of GaN and the formation of a primary recrystallized structure suitable for the secondary recrystallized grains having the (110) [001] orientation to be sufficiently developed are essential. is there.

Here, as the inhibitor, fine precipitates such as MnS, MnSe, and AlN are generally used.
It has also been practiced to add an element of a grain boundary segregation type such as Sb and Sn as disclosed in JP-A-51-13469 and JP-B-54-32412 to reinforce the effect of the inhibitor.

On the other hand, various measures have been taken in the respective steps of hot rolling and cold rolling to form an appropriate primary recrystallized structure. For example, in the case of the strong cold rolling method using AlN as an inhibitor, -26493, Japanese Patent Publication No. 54-13846
It is particularly effective to impart a heat effect during cold rolling such as warm rolling or inter-pass aging as disclosed in Japanese Patent Application Publication No. 54-29182 and Japanese Patent Publication No. 54-29182. This technology attempts to form a suitable texture by changing the deformation mechanism of the material during rolling by using the interaction between dislocations and N, C, which are solid solution elements in steel. .

However, none of the above prior arts is an advantageous method in consideration of productivity, and good magnetic properties are not always stably obtained. For example, in the case of warm rolling, implementation on an industrial scale is still technically difficult. Regarding the aging between passes, it is common to perform heat treatment a plurality of times in a coil state using a one-stand reverse rolling mill. This is because the heat treatment in the coil state cannot perform a uniform heat treatment over the entire length of the coil.

By the way, recently, in order to improve productivity, a technique using a tandem rolling mill having a plurality of stands is becoming mainstream. Rolling by a tandem rolling mill, unlike a reverse rolling mill, requires that the rolling distribution between passes and the rolling speed match, and compression deformation is inevitably more than tensile deformation. Therefore, the deformation mechanism of rolling is significantly different from that of the conventional method, and the conventional aging method cannot achieve a satisfactory effect, and in particular, an obstacle to the tandem rolling of a high magnetic flux density silicon steel sheet containing Al. Had become. In addition, due to the nature of tandem rolling, frequent aging treatments severely hinders production efficiency, so there is also a problem in places where it is not possible to perform multiple aging treatments to increase the effect as in the past. Was leaving.

DISCLOSURE OF THE INVENTION The present invention advantageously solves the above-mentioned problems, and even when the productivity is improved by using a tandem rolling mill, a new magnetic property capable of stably improving magnetic properties. It is an object of the present invention to propose a method for producing a highly oriented silicon steel sheet.

Now, the inventor has improved the magnetic properties more stably,
In addition, from both viewpoints of dramatically improving productivity, as a result of various studies in solving such a problem, by performing only one aging treatment on a rolled material cold-worked by tandem rolling, It has been found that oriented silicon steel sheets with excellent magnetic properties can be stably manufactured.

The present invention has been completed based on the above findings.

That is, the present invention is to hot roll the directional silicon steel material, and then perform one or two cold rolling sandwiching intermediate annealing, and then after decarburizing annealing, after applying an annealing separator,
In a method for manufacturing a grain-oriented silicon steel sheet comprising a series of steps of performing a final finish annealing, in the final cold rolling, first, a rolling reduction of 3 by tandem rolling:
After subjecting to 0-70% cold rolling, a continuous heat treatment is applied for 10 s to 10 min at a temperature range of 200 to 400 ° C. under a tension of 0.2 kg / mm ² or more. This is a method for producing a grain-oriented silicon steel sheet having excellent magnetic properties, characterized by having a sheet thickness.

In the present invention, when there is a material difference in the coil longitudinal direction before the final cold rolling, it is preferable to continuously change the continuous heat treatment temperature after tandem rolling according to the material difference in the coil longitudinal direction.

When such heat treatment in a low temperature range is performed continuously, it is preferable to use hot air as a heating means.

Further, in the present invention, when the directional silicon steel material contains AlN as a main inhibitor, the rolling reduction by tandem rolling is preferably 35 to 70%.

On the other hand, when the directional silicon steel material contains MnS and / or MnSe as a main inhibitor, the rolling reduction by tandem rolling is preferably set to 30 to 50%.

Here, the main inhibitor means an inhibitor of the dispersed second phase which is essential for causing the secondary recrystallization phenomenon after passing through the cold rolling process.
The use of segregation-type auxiliary inhibitors such as b, Se, Bi, and Sn is not prohibited.

Hereinafter, the present invention will be specifically described based on experimental results derived from the present invention.

C: 0.065wt% (hereinafter simply indicated as%), Si: 3.25%, Mn: 0.0
68%, P: 0.004%, S: 0.025%, solAl: 0.025% and N: 0.00
Oriented silicon steel material containing 8%, with the balance being substantially Fe, heated to a high temperature and then 2.2mm
Sheet thickness. Then, after pickling, 1.5 mm by cold rolling
After the intermediate plate thickness of 1 minute, intermediate annealing at 1100 ° C for 1 minute and Al
A quenching treatment for N deposition was performed.

A. Comparison between the tandem rolling method and the Zenjimer rolling method The following aging treatment was performed with the target of a final finished plate thickness of 0.23 mm.

(One aging treatment) 0.60 mm each in three-pass reverse rolling with a Sendzimer rolling mill and rolling with a three-stand tandem rolling mill
After rolling, the steel sheet was subjected to an aging treatment, and the rolling was continued in each rolling mill.

(Two aging treatments) When the same rolling is applied to each of the Sendzimir rolling mill and the tandem rolling mill, the aging treatment is performed at an intermediate thickness of 1.0 mm and 0.60 mm, and the rolling is continued to continue the final thickness: 0.23 mm.

(Three aging treatments) When the same rolling is performed in each of a Sendzimir rolling mill and a tandem rolling mill, the aging treatment is performed at an intermediate thickness of 1.0 mm, 0.60 mm, and 0.40 mm, and then the rolling is continued to continue the final sheet. Pressure: 0.23 mm.

Each aging treatment was performed at 300 ° C. for 2 minutes.

Thereafter, these steel strips were subjected to decarburizing annealing in wet hydrogen at 840 ° C. for 2 minutes, and then subjected to a final annealing after applying an annealing separator containing MgO as a main component.

 Table 1 shows the magnetic characteristics at this time.

As expected, the results in Table 1 show that the aging treatment has little effect on the improvement of the magnetic properties by tandem rolling,
It was considerably inferior to the case of Sendzimer rolling.

However, it should be noted that in tandem rolling, the magnetic properties do not change much even if the number of aging treatments increases. This indicates that the working deformation behavior is different from that of the reverse-type Sendzimer rolling.

Therefore, if the delivery is changed, the tandem rolling suggests that even a single aging treatment can improve the magnetic properties.

 Next, an experiment which led to the present invention will be described.

B. Tension effect in aging treatment After rolling to 0.60 mm with a tandem rolling mill using a part of the steel strip of the above-mentioned intermediate annealing and quenching treatment, the divided small steel strip was collected,
In a heat treatment furnace capable of imparting tension, 0, 0.1, 0.2, 0.5, 1.
300 ° C while applying tension of 5 and 3.0 kg / mm ² respectively
For 1 minute. Each small steel strip was again subjected to a tandem rolling mill to a final thickness of 0.23 mm.

Thereafter, these steel strips were subjected to decarburization annealing in wet hydrogen at 840 ° C. for 2 minutes, and then subjected to a final annealing after applying an annealing separation mold mainly containing MgO. Table 2 shows the magnetic properties at this time.

The results in Table 2 show that the magnetic properties are significantly improved when the aging treatment is performed under tension. In particular, when the aging treatment is performed under a tension of 0.2 kg / mm ² or more, even though the tandem rolling is performed, the magnetic properties are superior to those of the Zenzimer rolling.

The cause of such a phenomenon is not clear, but when C or N sticks to dislocations in the processed steel in the deformation behavior peculiar to tandem rolling, the sticking anisotropy of C or N appears due to the tension, It is thought to change the subsequent deformation behavior of the steel.

Next, an experiment which is a basis for determining the aging treatment conditions in the present invention will be described.

C. Examination of optimal rolling reduction when applying aging treatment After rolling at a rolling reduction in the range of 5 to 80% with a tandem rolling mill using a part of the steel strip after the above-described intermediate annealing-quenching treatment, Aging treatment was performed at 250 ° C. for 3 minutes while applying a tension of 0.5 kg / mm ² , followed by finishing with a Sendzimer rolling mill to a final thickness of 0.23 mm.

D. Examination of aging treatment and optimum temperature Using a part of the steel strip after the above-mentioned intermediate annealing-quenching treatment,
It was rolled by tandem rolling mill to 0.60 mm (rolling reduction 60%), then while applying a tension of 1.5 kg / mm ^2, and heat-treated for 60 seconds in a temperature range of 500 ° C. from 100 ° C., subsequently final plate in tandem mill Finished to a thickness of 0.23mm.

E. Examination of aging treatment and optimal time Rolling to 0.50mm with a tandem rolling mill (67% reduction)
Then, while applying a tension of 0.3 kg / mm ^2, the small steel strip was subjected to heat treatment at 350 ° C. for 3 seconds to 1 hour, and then finished to a final thickness of 0.23 mm by a tandem rolling mill.

Thereafter, each final rolled material is stored at 840 ° C, 2
After decarburizing annealing for 1 minute, an annealing separator containing MgO as a main component was applied, and then final annealing was performed.

Tables 3 to 5 show the results obtained by examining the magnetic properties of the steel sheets thus obtained.

From the results in Tables 3 to 5, the proper aging treatment conditions in the present invention are as follows: the temperature is 200 to 400 ° C., which is narrower than the conventional range, and the time is 10 seconds to 10 minutes, which is relatively short. Sufficient magnetic properties can be obtained by the aging treatment. And it turns out that in tandem rolling before performing such an aging treatment, it is necessary to perform rolling at a draft of 35 to 70%.

Further, the above-mentioned effect is similarly observed in a directional silicon steel material containing MnS and / or MnSe as a main inhibitor, and the aging condition in this case is the same as that when AlN is used as a main inhibitor. Optimum range of rolling reduction in tandem rolling before aging treatment is 30-50%
It has been confirmed that it is preferable to set it somewhat lower.

Thus, a grain-oriented silicon steel sheet having good magnetic properties can be obtained. However, in the above-described manufacturing method, in some rare cases, the magnetic properties vary in the longitudinal direction of the steel sheet.

 Hereinafter, the process of elucidating this point will be described.

C: 0.062%, Si: 3.15%, Mn: 0.080%, P: 0.005%, S: 0.026
%, SolAl: 0.024%, N: 0.0085% and Cu: 0.08%
The remainder was made of a directional silicon steel material having a substantially Fe composition, continuously cast, reheated to a high temperature, and then hot-rolled to a thickness of 2.2 mm. Thereafter, the intermediate process plate subjected to the precipitation treatment of AlN by hot-rolled sheet annealing at 1100 ° C. for 1 minute and subsequent quenching to room temperature was used as a test material. Finish annealing treatments were performed, and the effects of these treatments on the magnetic properties were investigated.

In FIG. 1, when cold-rolled at a reduction of 35%, then subjected to one pass heat treatment (additional tension: 0.5 kg / mm ² ) at various temperatures, and then cold-rolled to a thickness of 0.30 mm of, showing the relationship between the interpass annealing temperature and the magnetic flux density B _8. Where the symbols L, M,
T corresponds to the test materials collected from the front end, center, and rear end of the same hot rolled coil, respectively.

As can be seen from the figure, although the magnetic flux density is improved by performing the inter-pass heat treatment, the optimum value of the inter-pass heat treatment temperature may differ depending on the longitudinal direction even in the same coil.

In such a case, it is expected that it is difficult to secure stable magnetic characteristics over the entire length of the coil by one heat treatment between passes at a constant temperature.

Therefore, as a result of repeated examination of the cause of the difference in the optimum temperature, it was found that the size and the C content of the crystal grains before the cold rolling were different in the longitudinal direction of the coil. The reason for this is that decarburization occurs due to self-annealing after coiling of the hot-rolled coil, and at this time, there is a difference in the amount of decarburization due to different cooling conditions between the outside and inside of the coil. It is considered that the time between finish rolling differs between the leading end and the trailing end of the coil, and the difference in recrystallization behavior during hot rolling affects the crystal grain size in the subsequent step. It is considered that the optimal heat treatment temperature changes in the longitudinal direction of the coil as a result of such factors being intertwined.

Therefore, next, a method for eliminating the difference in the optimum heat treatment temperature in the coil was examined.

FIG. 2 shows the results of examining the effect of the rolling reduction in the intermediate cold rolling before the inter-pass heat treatment on the in-coil variation of the optimum heat treatment temperature.

As is clear from the figure, the variation decreases as the rolling reduction increases, but when it exceeds 70%, the magnetic characteristics deteriorate significantly, and the temperature difference cannot be completely eliminated. Although a method of changing the heat treatment time was also studied, the time difference is inappropriate for implementation on an industrial scale.

Therefore, it was concluded that changing the heat treatment temperature in accordance with the coil longitudinal direction is the most realistic method to secure the characteristics in the coil longitudinal direction by one heat treatment.

The inventors have also studied specific means of heat treatment.

As a result, normal electric heater heating and gas combustion heating type heating furnaces can be used, but in this case, the temperature rise / fall response is poor, and it is quite difficult to change the temperature in synchronization with the coil at a realistic coil passing speed. Proved difficult. Further, the infrared heater type is suitable in terms of securing the passing speed, but has a problem in that the equipment is expensive in a suitable manner. In this regard, since the temperature of the hot blast stove can be controlled in accordance with the amount of hot air blown, it can be said that the heating method is suitable for the present invention. In this case, by continuously adjusting the amount of hot air blow for each of the plurality of zones, heat treatment at different temperatures in the longitudinal direction can be performed while synchronizing with the coil according to the position of the passing coil.

Next, the preferred component composition of the directional silicon steel material according to the present invention will be described.

If the Si content is too small, the electric resistance becomes small and good iron loss characteristics cannot be obtained. On the other hand, if the Si content is too large, cold rolling becomes difficult. Therefore, the range of about 2.5 to 4.0% is suitable.

Concerning the components to be contained as inhibitors, the case where Al is not contained as a main component and the case where Al is contained are slightly different.

When Al is not contained, since Al is an unnecessary component, it is better to reduce as much as possible from the viewpoint of magnetism, and it is desirable to set the content to 0.005% or less. Similarly, it is preferable to reduce N, but much effort is required to reduce N, and it is also a component that is slightly effective for aging treatment. Therefore, the range of about 0.001 to 0.005% is preferable. Inhibitors at this time mainly include MnS and / or MnSe.
The range of S and Se suitable for precipitating S and MnSe finely is about 0.01 to 0.04% in both cases alone and in combination. Note that Mn is required as an inhibitor component as described above, but if it is too much, it is difficult to form a solution, so 0.05 to 0.15
% Is preferred.

On the other hand, when Al is contained, since Al and N play an important role as inhibitors, it is necessary to add a certain amount or more, but if too much, fine precipitation becomes difficult, so that 0.01 ≦ Al
The range of ≦ 0.15%, 0.0030 ≦ N ≦ 0.020% is preferable.

In this case, S and Se may be contained as an inhibitor-forming element.

In addition to the above, in order to improve magnetism, Sb, Cu, Sn, B, G
An inhibitor-reinforcing element such as e can be added as appropriate, and the range may be a known range. Further, in order to prevent surface defects due to thermal embrittlement, it is preferable to add Mo in the range of 0.005 ≦ Mo ≦ 0.020%.

A known manufacturing method is applied to the manufacturing process of the steel material, and the manufactured ingot or slab is regenerated as required, adjusted in size, heated, and hot-rolled. The final strip thickness of the steel strip after hot rolling is obtained by one cold rolling or two cold rollings with intermediate annealing.

At this time, the rolling reduction in tandem rolling before the aging treatment is 30 to 50% when Al is not contained, and 35 to 70% when Al is contained. The reason why the preferred ranges are different between the two is considered to be the effect of the difference in the amount of solute C. If the rolling reduction of tandem rolling before the aging treatment is out of the above range, a sufficient aging treatment effect cannot be obtained. Aging treatment
The short-time heat treatment for 10 seconds to 10 minutes in the temperature range of 200 to 400 ° C is advantageous in that the continuous heat treatment is superior in the uniformity of the aging treatment in the longitudinal direction of the steel strip and also in terms of imparting tension. is there. If the aging time and temperature are out of the range, the aging effect is small and good effects cannot be obtained.

It is the most important point of the present invention to apply tension during such aging treatment. That is, by applying tension during the aging treatment, not only the adverse effects on the rolling structure caused by tandem rolling are eliminated,
Rather, a remarkable improvement effect can be obtained as compared with the conventional reverse rolling. This is a phenomenon that could not be predicted by the conventional theory, and is presumably because C and N fixation behavior to dislocations becomes anisotropic with respect to the tension direction. Is completely new.

In this case, the tension to be applied is less than 0.2kg / mm ^2,
Since a satisfactory effect cannot be obtained, the applied tension is 0.2k.
g / mm ² or more (preferably 10 kg / mm ² or less).

The tension application in the present invention is to be applied substantially in a range where the steel sheet temperature is high, and in a normal continuous annealing furnace, although it is applied by dancer rolls arranged at the entrance and exit of the furnace, As in the case of a floating furnace, any well-known method is applicable, such as a method of applying the steel sheet using its own weight.

After the above-mentioned aging treatment, the rolling is continued to the final thickness. This rolling may be tandem rolling or conventional reverse rolling.

Here, the rolling reduction in the final cold rolling step is preferably 55% to 75% when Al is not contained, and is preferably 80% to 95% when Al is contained. When Al is contained, it is desirable that the cooling of the annealing before the final rolling be a quenching treatment as is known. In any case, the present invention is characterized in that a short-time aging treatment is performed during the final rolling, and the rolling up to the aging treatment is performed by a tandem rolling mill including a plurality of stands.

This aging treatment is very different from the conventional method in that it only needs to be performed once.

The steel strip after rolling is decarburized and annealed by a known method, then coated with an annealing separator containing MgO as a main component, wound into a coil and subjected to final finish annealing, and then if necessary. However, it is needless to say that the magnetic domain refining treatment can sometimes be performed by laser, plasma, electron beam, or other methods.

By the way, usually, a hot-rolled coil is wound at a temperature in the range of 500 to 800 ° C. At this time, decarburization occurs by self-annealing. At this time, if the cooling condition is different between the outside and the inside of the coil, the C content varies in the longitudinal direction of the hot rolled sheet. Such a phenomenon depends on the single weight of the coil and the winding temperature, but an uneven portion is generated in a region of about 1 to 2 ton at each of the leading end and the trailing end of the coil. Therefore, in such a case, at least the tip 2 ton (L) in the heat treatment furnace passing plate of the coil.
It is desirable that the heat treatment temperature be continuously changed to the optimum temperature at a position from the center to the center (M) and from the center to the rear end 2 ton (T).

Here, the optimum temperature at the above-mentioned portion in the longitudinal direction is the material component,
At the time of hot rolling, it is affected by the crystal behavior, the amount of C removed after winding the hot-rolled coil, and the like, but is generally in the following range.

_{250 ℃ ≦ T L ≦ 400 ℃} (T L -50) ℃ ≦ T M ≦ (T L -50) ℃ (T L -50) ℃ ≦ T T ≦ (T L -20) a brief description of ° C. drawings FIG. 1 is a graph showing the effect of the inter-pass heat treatment temperature on the magnetic properties, and FIG. 2 is a graph showing the relationship between the rolling reduction and the variation in the optimum heat treatment temperature in the coil during intermediate cold rolling before the inter-pass heat treatment. It is.

BEST MODE FOR CARRYING OUT THE INVENTION Example 1 C: 0.060%, Si: 3.25%, Mn: 0.075%, P: 0.009%, S: 0.009
%, SolAl: 0.025%, N: 0.020%, Sb: 0.025%, Cu: 0.06%, M
A slab was obtained by melting a directional silicon steel material containing o: 0.013% and N: 0.008%, and substantially consisting of the balance of Fe, and then by continuous casting. Then, after heating at 1450 ° C. for 10 minutes, a hot-rolled coil having a thickness of 2.7 mm was formed by ordinary hot rolling.
Then, after annealing at 1000 ° C for 1 minute, pickling, 1.50mm
Intermediate plate thickness. After further annealing at 1100 ° C for 2 minutes, quenched and then 0.6m with a three-stand tandem rolling mill
Rolled to a thickness of m. Subsequently, after aging treatment was performed in a continuous furnace at 350 ° C. for 2 minutes under a tension of 0.5 kg / mm ² , reverse rolling was performed using a Sendzimer mill to finish to a final thickness of 0.23 mm.

Thereafter, decarburization annealing was performed at 840 ° C. for 2 minutes in wet hydrogen, MgO containing 5% TiO ₂ was applied, and then final finishing annealing was performed at 1200 ° C. for 10 hours.

 The magnetic properties of the steel sheet thus obtained are shown below.

B ₈ : 1.945T, W _17/50 : 0.82W / kg Example 2 Slabs having various compositions shown in Table 6 were made into a 2.2 mm thick hot-rolled coil in the same manner as in Example 1, and after pickling. , And then cold-rolled to a thickness of 1.6 mm, intermediately annealed at 1050 ° C. for 1 minute, quenched, and rolled to an intermediate thickness of 0.80 mm with a tandem rolling mill having four stands, and each was divided into two.

One of the divided cold rolled sheets was subjected to an aging treatment at 250 ° C. for 5 minutes in a continuous furnace while applying a tension of 1.5 kg / mm ² , and then to the final sheet thickness of 0.20 mm using the same tandem rolling mill. This is a finish compatible example.

One that remains, while applying a tension of 0.1kg / mm ^2, 250 ℃
For 5 minutes in a continuous furnace, and the same tandem rolling mill was used to finish the sheet to a final thickness of 0.20 mm, which was used as a comparative example.

Then, both were subjected to decarburizing annealing at 840 ° C. for 2 minutes in wet hydrogen, and after applying MgO containing 7% TiO ₂ ,
Final finishing annealing was performed at ℃ for 10 hours.

The results obtained by examining the magnetic properties of each steel sheet thus obtained are also shown in Table 6.

Example 3 Slabs having various compositions shown in Table 7 were formed into a hot-rolled coil having a thickness of 2.2 mm in the same manner as in Example 1, and after pickling, 0.65 mm
The steel sheet was cold-rolled to a thickness, then subjected to intermediate annealing at 1000 ° C. for 1 minute, and then rolled to an intermediate thickness of 0.35 mm by a tandem rolling mill having five stands, and then divided into two parts.

For one of the divided cold-rolled sheet, while applying a tension of 0.3 kg / mm ^2, performs an aging treatment for 2 minutes in a continuous furnace at 300 ° C., subsequently adapted finished to a final thickness of 0.23mm in Sendzimir rolling mill Example.

One that remains, while applying a tension of 0.05 kg / mm ^2, 300
An aging treatment at 2 ° C. for 2 minutes was performed in a continuous furnace, and the same Sendzimir mill was used to finish the sheet to a final thickness of 0.23 mm, which was used as a comparative example.

Then, after performing decarburization annealing at 840 ° C. for 2 minutes in wet hydrogen, MgO was applied, and final finishing annealing was performed at 1200 ° C. for 5 hours.

The results obtained by examining the magnetic properties of each steel sheet thus obtained are also shown in Table 7.

Example 4 C: 0.040%, Si: 3.42%, Mn: 0.068%, P: 0.002%, S: 0.002
%, Se: 0.022%, Sb: 0.026% and Mo: 0.011%
A directional silicon steel material having a composition substantially equal to the balance of Fe was melted and continuously cast to obtain a slab. After heating the slab at 1450 ° C for 15 minutes at a high temperature for a short time, the sheet thickness is 2.
A 0 mm hot rolled coil was used. The winding temperature is 650 ° C and the unit weight of the coil is 20 tons. At the time of this winding, there was a slight difference in the material in the longitudinal direction of the coil.

After that, after performing hot-rolled sheet annealing at 1000 ° C for 1 minute,
The first cold rolling was performed at a rolling reduction of 70%, and after an intermediate annealing at 950 ° C. for 1 minute, the temperature was gradually cooled to 800 ° C. and then rapidly cooled to 250 ° C. Next, after performing tandem rolling at a cold rolling reduction of 35%, heat treatment between passes was performed for 3 minutes in a hot air aging furnace under the conditions shown in Table 8. The additional tension at this time was 0.5 kg / mm ² .

After finishing to a final thickness of 0.23 mm, performing decarburization and primary recrystallization annealing at 820 ° C for 2 minutes, applying an annealing separator mainly composed of MgO, and then final finishing annealing at 1200 ° C Was given.

Table 8 also shows the results obtained by examining the magnetic properties in the longitudinal direction of the obtained product.

In the table, 1 ton at the tip is the tip, and 1 ton at the rear
As the rear end and the remainder as the center.

Example 5 C: 0.070%, Si: 3.28%, Mn: 0.074%, P: 0.002%, S: 0.002
%, Se: 0.021%, Sb: 0.026%, solAl: 0.026%, Cu: 0.07%,
N: 0.0087% and Mo: 0.012%, with the balance being substantially Fe
Melting and continuous casting of directional silicon steel material with composition
Slab. Then, after heating the slab at 1420 ° C. for 20 minutes at a high temperature for a short time, a hot-rolled coil having a thickness of 2.2 mm was formed by ordinary hot rolling. The winding temperature is 550 ° C and the unit weight of the coil is 20ton. At the time of this winding, there was a slight difference in the material in the longitudinal direction of the coil.

Thereafter, the steel sheet was cold-rolled to a thickness of 1.5 mm, subsequently subjected to intermediate annealing at 1100 ° C for 1 minute, gradually cooled to 950 ° C, and rapidly cooled to 200 ° C or less. Next, after performing tandem rolling at a cold rolling reduction rate of 55%, heat treatment between passes was performed for 2 minutes in a hot air aging furnace under the conditions shown in Table 9. The additional tension at this time is 0.
It was 8 kg / mm ² .

After finishing to a final thickness of 0.23 mm, decarburizing and primary recrystallization annealing at 840 ° C for 3 minutes, applying an annealing separator mainly composed of MgO, and then final finishing annealing at 1200 ° C Was given.

Table 9 also shows the results of examining the magnetic properties in the longitudinal direction of the obtained product.

In the table, 1 ton at the tip is the tip, and 1 ton at the rear
As the rear end and the remainder as the center.

Example 6 C: 0.041%, Si: 3.35%, Mn: 0.070%, P: 0.002%, S: 0.002
%, Se: 0.021%, Sb: 0.025% and Mo: 0.012%,
A directional silicon steel material having a composition substantially equal to the balance of Fe was melted and continuously cast to obtain a slab. After heating the slab at 1450 ° C for 15 minutes at a high temperature for a short time, the sheet thickness is 2.
A 4 mm hot-rolled coil was used. The winding temperature is 650 ° C and the unit weight of the coil is 10 tons. At the time of this winding, a considerable material difference occurred in the longitudinal direction of the coil.

After that, after performing hot-rolled sheet annealing at 1000 ° C for 1 minute,
The first cold rolling was performed at a rolling reduction of 70%, and after an intermediate annealing at 950 ° C. for 1 minute, the temperature was gradually cooled to 800 ° C. and then rapidly cooled to 250 ° C. Next, after tandem rolling at a cold rolling reduction of 35%, inter-pass heat treatment was performed for 5 minutes in a hot air aging furnace under the conditions shown in Table 10. The additional tension at this time was 0.5 kg / mm ² .

After finishing to a final thickness of 0.23 mm, performing decarburization and primary recrystallization annealing at 820 ° C for 2 minutes, applying an annealing separator mainly composed of MgO, and then final finishing annealing at 1200 ° C Was given.

Table 10 also shows the results of examination of the magnetic properties of the obtained product in the longitudinal direction.

In the table, 1 ton at the tip is the tip, and 1 ton at the rear
As the rear end and the remainder as the center.

Example 7 C: 0.060%, Si: 3.21%, Mn: 0.072%, P: 0.004%, S: 0.002
%, Sol.Al: 0.025%, Se: 0.020%, Sb: 0.027%, Cu: 0.07%,
Mo: 0.013% and N: 0.0085%, with the balance being substantially Fe
A silicon steel material was melted and continuously cast to obtain a slab. Then, the slab was heated at 1450 ° C. for 10 minutes at a high temperature for a short time, and then subjected to ordinary hot rolling to form a hot-rolled coil having a thickness of 2.2 mm. The winding temperature is 500 ° C and the coil unit weight is 20ton.
At the time of this winding, a considerable material difference occurred in the longitudinal direction of the coil.

Then, after performing hot-rolled sheet annealing at 1100 ° C for 1 minute,
After gradually cooling to 900 ° C., it was rapidly cooled to 200 ° C. or less. Next, after tandem rolling at a rolling reduction of 45%, inter-pass heat treatment was performed for 5 minutes in a hot air heat treatment furnace under the conditions shown in Table 11. The additional tension at this time was 0.3 kg / mm ² .

Then, after finishing to a final thickness of 0.30 mm,
After decarburization for 1 minute and primary recrystallization annealing, an annealing separator containing MgO as a main component was applied, and then final finishing annealing was performed at 1200 ° C. for 10 hours.

Table 11 shows the results of examination of the magnetic properties in the longitudinal direction of the obtained product.

In the table, 1 ton at the tip is the tip, and 1 ton at the rear
As the rear end and the remainder as the center.

Example 8 C: 0.064%, Si: 3.25%, Mn: 0.070%, P: 0.003%, S: 0.023
%, Sol. Al: 0.026%, N: 0.0088%, Cu: 0.07%, Sn: 0.05%, and Mo: 0.012%, and the balance is substantially Fe. In the same manner as in (1), a hot-rolled sheet was prepared (winding temperature: 550 ° C., single coil: 20 ton). At the time of this winding, a considerable material difference occurred in the longitudinal direction of the coil.

Then, it was cold-rolled to 1.4 mm, subsequently subjected to intermediate annealing at 1100 ° C. for 1 minute, gradually cooled to 900 ° C., and then rapidly cooled to 200 ° C. or less. Next, tandem rolling was performed at a cold rolling reduction rate of 40%.
Inter-pass heat treatment was performed for 3 minutes under the conditions shown in the table (where the front end was the 2 ton at the front end, the rear end was the 2 ton at the rear end, and the rest was the center). The additional tension at this time was 0.5 kg / mm ² .

After finishing to a final thickness of 0.23mm, decarburizing and primary recrystallization annealing at 840 ° C for 2 minutes, applying an annealing separator mainly composed of MgO, and then final finishing annealing at 1200 ° C for 10 hours Was given.

Table 12 shows the results of examination of the magnetic properties in the longitudinal direction of the obtained product.

Industrial Applicability Thus, according to the present invention, in the final cold rolling step, by effectively combining tandem rolling and aging treatment, it is possible to achieve a stable improvement of magnetic properties under the improvement of productivity, In the production of Al-containing oriented silicon steel sheets, the ability to apply an efficient production method called tandem rolling is extremely useful in the production of high magnetic flux density oriented silicon steel sheets.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiaki Iida 2-88 Wakihama Kaigandori, Chuo-ku, Kobe City, Hyogo Prefecture Inside the Hanshin Works of Kawasaki Steel Co., Ltd. Kawasaki Steel Corp. Technology Research Division (58) Field surveyed (Int. Cl. ⁶ , DB name) C21D 8/12

Claims (5)

(57) [Claims] (1) After hot rolling a directional silicon steel material,
A method for producing a grain-oriented silicon steel sheet comprising a series of steps of performing cold rolling once or twice with an intermediate annealing therebetween, followed by decarburizing annealing, applying an annealing separator, and then performing final finishing annealing. In the final cold rolling, the rolling reduction is first by tandem rolling: 30
After subjected to 70% cold rolling, 0.2 kg / mm ² or more subjected to continuous heat treatment of 10s~10min in the temperature range of 200 to 400 ° C. under tensioning, then we continue to continue the cold-rolled final plate A method for producing a grain-oriented silicon steel sheet having excellent magnetic properties, characterized by being thick. 2. A magnetic characteristic according to claim 1, wherein a continuous heat treatment temperature after tandem rolling is continuously changed in accordance with the material difference in the coil longitudinal direction when a hot rolled coil having a material difference in a longitudinal direction is treated. Manufacturing method of excellent oriented silicon steel sheet. 3. The method for producing a grain-oriented silicon steel sheet according to claim 1, wherein the continuous heat treatment after tandem rolling utilizes hot air. 4. The grain-oriented silicon steel sheet according to claim 1, wherein the grain-oriented silicon steel material contains AlN as a main inhibitor, and has a magnetic reduction of 35 to 70% by tandem rolling, and has excellent magnetic properties. Manufacturing method. 5. The directional silicon material according to claim 1, wherein the directional silicon steel material contains MnS and / or MnSe as a main inhibitor and has a reduction rate of 30 to 50% by tandem rolling. Manufacturing method of raw steel sheet.