JPH01139723A - Manufacture of grain-oriented silicon steel sheet excellent in magnetic property - Google Patents

Abstract

PURPOSE:To improve magnetic flux density and to reduce iron loss by specifying the length of holding time in a high-temp. region in slab heating and annealing conditions just before the final cold rolling at the time of manufacturing a grain-oriented silicon steel sheet having a specific composition. CONSTITUTION:A slab having a composition consisting of, by weight, 0.05-0.085% C, 2.0-4.0% Si, 0.01-0.20% Mn, 0.008-0.100% S and/or Se, 0.010-0.065% solAl, 0.003-0.013% N, 0.001-0.30% Zn, and the balance essentially Fe and containing, if necessary, 0.003-0.030% Mo is heated up to >=1400 deg.C while regulating holding time in a temp. region as high as >=1200 deg.C to <=70min, which is hot-rolled and then subjected to a single cold rolling or to two-times or more cold rollings, while subjected to process annealing between the above cold rolling stages, so as to be formed into a sheet of the final thickness. At the time of annealing just before the final cold rolling, heating is carried out at 900-1200 deg.C for 10-300sec and cooling from 750 to 100 deg.C at the time of cooling is carried out within 175sec. After the final cold rolling, decarburizing annealing and final finish annealing are applied to the cold-rolled steel sheet.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a grain-oriented silicon steel sheet with excellent magnetic properties, that is, high magnetic flux density and low core loss.
In particular, it is intended to advantageously improve magnetic properties by strengthening the suppressing power of the inhibitor and effectively controlling the primary recrystallization structure.

(Prior Art) Characteristics required of a grain-oriented silicon steel sheet are high magnetic flux density and low iron loss. Conventionally, methods for reducing iron loss include increasing the Si content, reducing the product thickness, reducing impurities, and changing the secondary recrystallized grain orientation from (110) to (001).
) orientation, that is, the Goss orientation, and reducing the size of secondary recrystallized grains are known. here 2
As a method for increasing the degree of Goss orientation accumulation of secondary recrystallized grains, for example, the final strong cold ductility of an AI-containing material as described in Japanese Patent Publication No. 15644/1980, and the method described in Japanese Patent Application Laid-Open No. 12610/1980 A method of manufacturing from a B-containing material as described above is known.

(Problems to be Solved by the Invention) According to these methods, the degree of Goss orientation accumulation of secondary recrystallized grains is certainly increased, but on the other hand, coarsening of the secondary recrystallized grains is unavoidable, and this Therefore, the problem remained that the iron loss of the product actually deteriorated.

This invention advantageously solves the above-mentioned problems by increasing the degree of Goss orientation integration of secondary recrystallized grains, and reducing the iron loss of the product sheet by reducing the grain size rather than increasing it. The purpose of this paper is to propose an advantageous manufacturing method for unidirectional silicon steel sheets that also improves magnetic flux density.

(Means for Solving the Problems) As a result of intensive research in order to solve the above problems, the inventors have found that (a) a high magnetic flux density directional structure using MnS and/or MnSe and AIN as inhibitors; By further incorporating Zn into the material for raw steel sheets, secondary recrystallized grains can be refined and iron loss can be improved without impairing magnetic flux density. (b) Rapid heating of slabs in high temperature range Heat to 1400°C
(c) Annealing immediately before final cold rolling to 900 to 1
Performed at 200°C, and from 750°C to 100°C
New findings were obtained that by increasing solid solution C by cooling within 175 seconds, the primary recrystallization texture was improved and the magnetic flux density was increased.

Furthermore, we have also found that by applying ultrasonic vibration to the steel sheet during cold rolling, the magnetic properties of the unidirectional silicon steel sheet can be further improved.

This invention is based on the above knowledge.

That is, this invention has the following properties: C: 0.025 to 0.085 wt% (hereinafter simply expressed as %) Si: 2. O ~ 4.0% Mn: 0.01 ~ 0.20% S and Se
At least one of: 0, 008 to o. ioo% sol Contains Al: 0.010 to 0.065% and N: 0.003 to 0.013%, and Zn: 0.001 to 0.30%, and the remainder is substantially composed of Fe. A series of steps in which a steel slab is heated, hot rolled, then cold rolled once or twice with an intermediate annealing to achieve the final thickness, decarburized and then final annealed. A method for producing grain-oriented silicon steel sheets comprising the steps of: i) heating the slab to a temperature of 1400°C or higher with a residence time in a high temperature range of 1200°C or higher within 70 minutes; ii) final cold rolling. Annealing immediately before 900~
The temperature is 1200℃ for 10 to 300 seconds, and the cooling from 750℃ to 00℃ is 175℃.
This is a method for manufacturing a unidirectional silicon steel sheet with excellent magnetic properties (first invention), which comprises manufacturing the unidirectional silicon steel sheet with excellent magnetic properties.

In addition, this invention contains Mo in the above material from 0.003 to 0.
．． This is a manufacturing method (second invention) in which the content is in the range of 0.030%.

This invention will be specifically explained below.

First, the experimental results that led to this invention will be described.

Experiment T Effect of Zn addition C: 0.065%, Si: 3.20%, Mn:
0.075%, S: 0.025%, sol Al
Z: 0.025% and N: 0.008%, and the remainder is substantially Fe.
A total of 12 steel ingots were cast with no addition of n and with various amounts of n added in the range of 0.0001 to 1%.

After heating these steel ingots to 1200°C, they are bloomed and rolled.
Next, it was heated to 1350″C and then hot rolled to form 2
．． It was made into a hot rolled sheet with a thickness of 0 m. Then at 1100°C in N2,
After hot-rolled sheet annealing for 3 minutes, the sheet was slowly cooled to 900''C, rapidly cooled to 400C with mist, and then allowed to cool.

Next, after finishing it to 0.20ma+ thickness by one cold rolling,
Decarburization annealing at 850°C for 15 minutes at 1X Hz,
After that, after applying a separating agent mainly composed of MgO, II□
Finish annealing was carried out at 1200° C. for 510 hours.

FIG. 1 shows the results of examining the magnetic properties, secondary particle size, and surface flaw occurrence rate of the product sheet thus obtained.

As is clear from the figure, Z
When n is contained in a range of 0.001 to 0.30%, the secondary particle size becomes smaller in the product sheet, resulting in a significant reduction in iron loss.

Experiment ■ Slab high temperature 2. Effect of heat CF 0.060%, Si: 3.20%, Mn:
0.078%, Se: 0.023%, sol Al
: 0.020%, N: 0.009%, Zn:
A steel containing 0.05% and Mo: 0.010%, with the remainder essentially having a composition of Pe, was cast, heated to 1200°C, then bloomed and further divided into 28 pieces.

Next, after heating to 1,200°C, the final temperature was varied from 1,350°C to 1,450'C using an induction heating furnace, and the time required to reach the final temperature was varied. After holding for a minute, hot rolling is performed.2. A hot-rolled sheet with a thickness of Oma+ was obtained. Then N2
After hot-rolled plate annealing at 1100'C for 13 minutes in
Slowly cooled to 00'C, then quenched to 100°C with mist, then left to cool to 0.20aII with one cold rolling.
After finishing thickly, decarburization annealing was performed at 850°C for 15 minutes in wet H2, after which a separating agent mainly composed of MgO was applied, and then annealing was performed in an atmosphere of 25%-11□Nm of 5% Nm; The temperature was raised to 1200°C at a heating rate of 1200°C/h, and then +1. Inside, TOH purification annealing was performed.

Ta.

The 81° value of the product board thus obtained is shown in FIG.

As is clear from the figure, when the slab is heated rapidly and at a high temperature of 1400° C. or higher, the magnetic flux density of the product is improved.

Experiment■ Annealing and cooling conditions immediately before final cold rolling The rimmed treatment time of molten steel was changed, and steel ingot A (C: 0.064%) and steel ingot B were mainly differed only in C content.
(C: 0.055%) and steel ingot (C: 0.0
33%) was dissolved. Other components are Si: 3.06
~3.18%, Mn: 0.065 ~0.07
2%, S20,021~0.023%
, sol Al: 0.025-0.023%, N
: 0.007-0.023%, Zn: 0.08
% range.

After heating these steel ingots to 1200°C, the temperature was raised to 1420°C in 30 minutes using an induction heating furnace, and immediately hot rolled into a hot rolled plate having a thickness of 2.3 mm.

Next, after dividing into 5 parts, hot-rolled sheets were annealed at 1150'C for 13 minutes in N2, after which the amount of N2 gas for cooling was changed, the sheets were rapidly cooled with mist, and the sheets were immersed in water or hot water. The cooling treatment shown by the cooling curve in Figure 3 was performed.

Thereafter, after analyzing the amount of solid solute C in the steel, the steel plate was further divided and rolled at a temperature ranging from 50°C to 300°C. The temperature during rolling was adjusted by cooling with rolling oil, using heated rolling oil, or heating the steel plate.

In addition, for some parts, aging treatment is performed by heating the steel plate to 220°C for 2 minutes only between rolling passes, and for other parts, the steel plate is heated at a temperature of 150°C for 2 minutes.
1kHz at 30kHz using a Cyrisk type oscillator
Ultrasonic vibration was applied. The finished thickness of all copper plates was 0.20 mm.

Next, decarburization annealing was performed at 850°C for 13 minutes in wet H2, and then a separation agent mainly composed of MgO was applied, so N
The temperature was raised to 1200°C at a rate of 10'C/h in an atmosphere of 25%-Hz:75%, and then purification annealing was performed at 1200°C in an 11□ chamber for 10 hours.

Figure 4 shows the relationship between the amount of solid solute C before cold rolling, the annealing cooling rate, and the amount of C in the material.
BIG of the product board of products tested in the temperature range of 0 to 250℃
indicates the value of

As is clear from the figure, 750°C during annealing and cooling.
It can be seen that when the cooling time from ~100°C is regulated within 175 seconds, the amount of solid solute C in the steel plate after cooling is 0.02% or more, and the BIG value is also high.

Furthermore, the sample under cooling condition (d) is 7.
The cooling rate from 50'C to 350°C is almost the same as condition (C), but the cooling rate below 350°C is slow, so carbon precipitates as carbide, resulting in a decrease in solid solution C. , it seems that the desired magnetic properties could not be obtained. Thus, in order to ensure solid solution C, it is important to limit cooling to below 350'C and even to 100°C.

Figure 5 shows the BIO of a product plate that has been cooled under the cooling conditions shown in Figure 3 (b) for steel with a C content of 0.055%.
are shown under various cold rolling conditions. From this figure, by rolling at a temperature of 150 to 250°C,
It can be seen that a product with a high BIG value can be obtained. Furthermore, B1° of the sample subjected to ultrasonic vibration is extremely high.

Furthermore, it can be seen that the BIG improvement effect is small in the aging treatment between rolling passes, and the temperature during rolling is an important factor. This phenomenon can be interpreted as being due to the Cottrell effect. That is, solid solution C diffuses into the dislocations introduced by rolling and becomes fixed to the dislocations. This fixed C atmosphere prevented the movement of dislocations, resulting in an improvement in the structure. Increasing the temperature of the steel sheet facilitates the diffusion of solute C, but in order to prevent the movement of dislocations by creating a Cottrell atmosphere, it is necessary to diffuse solute C at the same time as introducing dislocations. .

Therefore, increasing the steel sheet temperature during rolling is more effective than interpass aging. Moreover, if the temperature of the steel plate is too high, overaging will occur, and the amount of C fixed to dislocations will decrease, which is not preferable. The improvement in properties by applying vibration to the steel sheet during rolling is also considered to be due to the effect of promoting the diffusion of C and fixing it to dislocations.

Figure 6 shows the texture of the primary recrystallized plate after decarburization annealing (1
10) Show as a pole figure.

Figure 6 (a) shows that in experiment (2), MB was used, and after annealing and cooling under the cooling conditions of Figure 3 (e), cold rolling was performed for 25 minutes.
One was annealed at a temperature of 0°C and then subjected to decarburization annealing. On the other hand, (b) in Fig. 6 was annealed under the cooling conditions shown in Fig. 3 (b), and the other conditions were the same as (a). .

As is clear from Figure 6, from 750°C to 100'C
The elephant, the cooled thing [same figure (b)] is (1111<
It can be seen that the 110> structure is reduced and the (1111<112> structure is increased. The orientation of the secondary recrystallized grains that increases B is (110) C00L), and the (1111<112> structure is increased.
112> and (554) <225> are known to be easily eaten by this grain, and as a result, (110)
Secondary recrystallized grains with (001) orientation grow, and the 81
(+111) If the <110> structure strongly remains (110) (Secondary recrystallized grains with orientation shifted from (101)
It is thought that the BIG of the product was inferior due to the growth of grains).

(Function) The reason why the component composition in this invention is limited to the above range is as follows.

C: 0.025-0.085% C effectively contributes to the refinement of grains after hot rolling, but if the content is less than 0.025%, not only is the above-mentioned refinement effect poor. , the microstructural improvement effect of solid solute C in cold rolling, which is one of the features of this invention, becomes insufficient, and on the other hand, if it exceeds 0.085%, decarburization by continuous annealing becomes difficult, which also deteriorates the magnetic properties of the final product. Therefore, the C content was limited to a range of 0.025 to 0.085%.

Si: 2.0-4.0% If Si is less than 2.0%, it is difficult to obtain the low iron loss value desired by this invention, while if it exceeds 4.0%, it becomes brittle. Since cold workability deteriorates significantly, Si
The content was limited to a range of 2.0 to 4.0%.

Mn: 0.01-0.20% Mn combines with S and Se described below to form MnS, Mn
1 in the final annealing to form Se and as an inhibitor.
(110) (00
1) It is a useful element for preferentially developing oriented secondary recrystallized grains, but if it is less than 0.01%, its effect is poor, while if it exceeds 0.20%, secondary recrystallization occurs. Since this does not occur, the content was limited to a range of 0.01 to 0.20%.

S and/or Se: 0.008-0.100%
As mentioned above, S and Se are useful elements that combine with Mn to form the inhibitors MnS and MnSe, and require at least o, oos%. However, if too large a quantity is added, in the case of S, hot Since Se has the disadvantage of causing cracks and increasing costs since it is an expensive element, the upper limit was set at 0.100% whether added alone or in combination.

sol Al: 0.010-0.065%,
N: 0.003 to 0.013% At and N also combine to form fine precipitates and function as IN to the inhibitor, but if the content is out of the above range, the dispersion state of the precipitates becomes grain growth. The content of 5olAl and N is 0.010 to 0.065% and 0.003%, respectively, because the state is inappropriate for effectively suppressing the ~
It was limited to a range of 0.013%.

Zn: 0.001-0.30% Zn is a particularly important element in this invention, and 2
This extremely effectively contributes to the refinement of secondary recrystallized grains and, in turn, to the reduction of iron loss values. However, if the Zn content is less than 0.001%, the addition effect will be poor, while if it exceeds 0.30%, the occurrence of surface defects such as bald spots will become significant, so the Zn content should be 0.001 to 0.30 % range.

Mo: 0.003 to 0.030% Mo is used not only to improve hot brittleness but also as an element to strengthen the suppressing power of the inhibitor, especially when the content of S and/or Se is high, It is preferable to add it when the heating temperature is high. However, Mo
If it is less than 0.003, the effect of the addition will be poor, while if it exceeds 0.030%, the magnetic properties will deteriorate, so the amount added should be in the range of 0.003 to 0.030%.

Next, a method for manufacturing a unidirectional silicon steel sheet according to the present invention,
The steps will be explained in order.

Generally known methods may be used for the steel making and hot rolling processes, except for slab heat treatment, but when heating the slab, use an induction heating method or the like to rapidly heat the slab to 1200°C or higher.
It is important to raise the temperature to a temperature above ℃. When the slab heating temperature reached is lower than 1400'C, the silicon steel slab having the composition of this invention has M
The solid solution of nS and/or MnSe is insufficient and a product with high magnetic flux density cannot be obtained. In addition, in slab heating,
If the residence time in the temperature range of 1200° C. or higher exceeds 70 minutes, the stabilization of magnetic properties is hindered due to coarsening of the crystal grains of the slab.

Then, the desired thickness is achieved by one cold rolling or two cold rollings with intermediate annealing, but the annealing immediately before the final cold rolling is performed at a temperature of 900 to 1200°C for 10 to 300 seconds. It is necessary to apply it at the bottom.

In the case of one cold rolling, the immediately preceding annealing corresponds to the annealing of the hot-rolled sheet, and therefore, hot-rolled sheet annealing is essential in order to achieve the desired thickness with one cold rolling. Become. On the other hand, when the desired plate thickness is obtained by cold rolling twice, hot-rolled plate annealing is not necessarily necessary because intermediate annealing is the annealing.

In the annealing immediately before the final cold rolling, if the treatment temperature is lower than 900°C or the time is shorter than 10 seconds, solid solution of C in the steel is insufficient, and conversely, if the temperature is lower than 900°C or the time is shorter than 10 seconds,
If the temperature exceeds ℃ or the time exceeds 300 seconds, Mn
Coarsening of S and/or MnSe occurs, and the magnetic properties of both deteriorate.

Furthermore, the cooling during this annealing was rapid cooling to 750°C.
The cooling time from to 100 °C is within 175 seconds,
The amount of solid solution C before cold rolling in the next process is 0.020%
Adjust as above. Since the amount of solid solute C after quenching depends on the total amount of C in the steel, if the total C1 is low, it is preferable to further increase the cooling rate and adjust the solid solute Cit to 0.020% or more.

When the amount of solid solution C is less than 0.020%, the effect of improving the primary recrystallization texture is small, and it is difficult to expect a satisfactory increase in magnetic flux density.

The final cold rolling is preferably performed at a rolling reduction ratio of about 81 to 95%, and the rolling at this time is preferably performed at a warm rolling temperature of 150 to 250°C.

Regarding the cold rolling temperature of unidirectional silicon steel sheet, N, P
, according to Goss (1953 The Iron A
ge February P147 You, 11 B
e Getting Better Electric
(alSheet and 5trips), many recommended rolling temperatures start at 840°F (44B, 9°C) and range from 200°F (93,3°C) to 400°F (
204.4°C). In this temperature range,
Various metallurgical phenomena occur, such as changes in the rolling slip system due to high temperatures and aging between rolling baths. It has been found that it is preferable to simultaneously introduce dislocations during aging, that is, to introduce dislocations through processing, and to move C to the dislocations. That is, the temperature of the steel plate during proper rolling is 15
It is characterized by a low temperature of 0 to 250℃, and it is characterized by the introduction of dislocations,
It is desirable to avoid aging between buses in the sense that C is moved at the same time. That is, this results in C
It is thought that the dislocations in the steel are fixed in a wide range and at a high density, resulting in a significant improvement effect on the primary recrystallization texture.

It will be done.

In actual rolling, part of the processing energy is converted into heat, so the temperature of the steel plate is between 100 and 150°C.
Therefore, in order to bring the temperature to 150 to 250°C, reduce or stop the application of rolling oil, which causes the temperature of the steel plate and rolls to drop, and heat the steel plate. easily achieved.

Further, at this time, by applying vibrations of 1 kW or more at 2 kHz or more to the steel plate, the magnetic properties of the product are further improved. This is thought to be due to promoting the movement of C during rolling. In this point, vibrations of less than 2 kHz and less than lk- have a small C migration promoting effect.

Next, decarburization annealing is performed, but this decarburization annealing is performed at a temperature of 700 to 90
This is carried out in a wet hydrogen atmosphere at 0° C. until the amount of C in the steel is approximately 0.003% or less.

After that, an annealing separator mainly composed of MgO is applied to the surface of the steel sheet, and then the temperature is raised to a temperature of 1100°C to 1250″C in a nitrogen, hydrogen, or mixed gas atmosphere, and further at this temperature, Finish annealing is performed in a hydrogen atmosphere to produce a product sheet.

During the final annealing, most of the inhibitor-forming elements S, Se, Al and N are removed, with S: 0.003% or less and Se: 0.003% or less, respectively.
003% or less, Al: o, oot% or less, N:
It is reduced to about 0.002% or less.

In addition, a tension coating is applied to the above-mentioned finish annealed plate,
It goes without saying that a product plate may be produced by flattening annealing in a temperature range of 700 to 900°C.

(Example) Blood loss A and C: 0.058%, St: 3.21%, Mn:
0.068%, S: 0.022%, sol Al
: '0.024%, N: 0.008% and Zn
: Heating a slab containing 0.054% Fe with the remainder essentially having a composition such that the residence time in a high temperature range of 1200°C or higher is adjusted to the various times shown in Table 1, After reaching the temperature shown in the same process table, hot rolling was performed to obtain a hot rolled sheet with a thickness of 2.3 mm.

These hot rolled sheets were then heated in N2 for 12 minutes at 1150°C, cooled from 750°C to 100°C in about 30 seconds using a mist, pickled, and then cold rolled at 200°C. In both cases, the plate thickness was 0.28 mm. Then,
Decarburization annealing was performed at 850°C for 13 minutes in a wet lh
After applying a separating agent mainly composed of Nz: 50%
-11z: Raise the temperature from 700"C to 1150"C at a heating rate of 7 °C/h in a 50% atmosphere, then switch to N2, and increase the temperature from 1150°C to 1200"C for 3
After heating at 0°C/h, hold at 1200°C for 8 hours,
After cooling to ℃, the atmosphere was switched to N2 for cooling. Thereafter, after removing the unreacted separating agent, the tension coating was baked to produce a product.

Table 1 shows the results of an investigation of the magnetic properties of the product board thus obtained.

As is clear from the table, the slab heating temperature is 1400℃
Above, when the residence time at 1200° C. or higher is 70 minutes or less, particularly good magnetic flux density and iron loss characteristics are obtained.

Example 2 C: 0.045%, Si: 3.29%, Mn:
0.072%, S: 0.008%, Se: 0
．． 019%, sol Ai! ,: 0.019
%, N: 0.0076%, Zn: 0.078
% and Mo: 0.012%, with the remainder being substantially Fe. The slab was heated to 1420'C in a high temperature range of 1200°C or higher for 35 minutes, and then processed to 420°C. After being held at ℃ for 5 minutes, hot rolling was performed to obtain a hot rolled plate having a thickness of 2.7 m+n.

This hot-rolled plate was partially annealed at 950°C for 2 minutes, the rest was pickled, and then cold-rolled for the first time to a thickness of 1.80 mm.
The intermediate plate thickness was set as . This steel plate was annealed at 1050°C for 3 minutes and then cooled using mist from 750°C to 100°C for various times shown in Table 2.

These steel plates were then cold rolled in a temperature range of 50°C to 250'C to a final thickness of 0.20mm.

Next, after decarburizing annealing at 840°C for 15 minutes in wet H2, a separation agent mainly composed of MgO was applied, and then N
z: 25%-〇, in an atmosphere of near 5% 8.
After heating up to 1200°C at a heating rate of 5'C/h, H
2 atmosphere was maintained at 1200°C for 12 hours, and then cooled to 600'C, and then switched to Nt and cooled. Then, after removing the unreacted separating agent, the tension coating was baked to produce a product.

Table 2 shows the results of investigating the magnetic properties of the product plates thus obtained.

As is clear from the same table, good magnetic properties were obtained when the cooling time from 750°C to 100°C during cooling during annealing immediately before final cold rolling was 175 seconds or less.

Example 3 C: 0.065%, St: 3.34%, Mn:
0.073%, S: 0.002%, Se: 0.0
23%, sol Aj! : 0.027%, N:
Contains 0.0065% and Zn: 0.034%,
The remainder is a slab of substantially Fe composition, as well as C:
0.046%, St: 3.34%, Mn: 0.
073%, S: 0.002%, Se: 0.02
2%, sol Al: 0.026% and N: 0.
0068 and 0.0003% Zn, respectively.
A slab containing 0.0005% of iron and 0.0005% of iron with the remainder being essentially Fe was heated for 2 hours in a high temperature range of 1200°C or higher.
The temperature was raised to 1435'C for 5 minutes, held for 15 minutes, and then hot rolled into a hot rolled sheet with a thickness of 3.0 mm.

These hot-rolled sheets were then pickled, cold-rolled for the first time to an intermediate thickness of 1.70 mm, and then rolled at 1100°C for 2
After annealing for 1 minute, annealing from 750℃ to 10” using a mist
It took 75 seconds to cool down to C. Next, 75℃ and 1
Cold rolling was carried out at a temperature of 50"C to give a final thickness of 0.18mm, but some steels containing Zn were rolled at 10kHz.
Ultrasonic vibration of 2 kHz was applied at Z during rolling. Next, decarburization annealing was performed at 860°C for 23 minutes in a humid 11□, and the MgO
After applying a separating agent mainly composed of
The temperature was raised in an atmosphere from 800°C to 1100°C at a heating rate of 5°C/h in an atmosphere of Nt: 20%-Nz: 80%, and then the atmosphere was switched to tri at 1100°C. The temperature was raised to 1200°C at a temperature increase rate of 25°C/h, and then held at 1200°C for 5 hours, cooled to 600°C, switched to N2 gas, and then cooled to room temperature.

Thereafter, after removing the unreacted separating agent, the tension coating was baked to produce a product.

Table 3 shows the results of investigating the magnetic properties of the product plates thus obtained.

As is clear from the table, good magnetic properties are obtained only when an appropriate amount of Zn according to the present invention is contained.

(Effects of the Invention) According to the present invention, it is possible to stably obtain a grain-oriented silicon steel sheet having excellent magnetic properties, particularly magnetic flux density and iron loss properties, which is advantageous.

[Brief explanation of the drawing]

Figure 1 shows Zn-containing Thi and Blot W+7/SO+
A graph showing the relationship between secondary particle size and surface flaw occurrence rate,
Figure 2 shows the influence of the residence time at 1200°C or higher and the heating temperature reached on the magnetic flux density during slab heating. Figure 3 shows the cooling temperature during annealing cooling immediately before the final cold rolling. The graph shown in Figure 4 shows the hardness versus time during cooling from 750°C to 100°C after annealing. g Graph showing the relationship between Cffi and B1°. Figure 5 is a graph showing the relationship between temperature during cold rolling and BIG. Figure 6 (a) and (b) are 750° after annealing. FIG. 3 is a pole figure showing a comparison of the primary recrystallization textures of decarburized annealed plates when the cooling rate between 100° C. is slow (a) and fast (b). Patent applicant Kawasaki Steel Corporation Figure 1 Zn4 amount (%) ◎I, 94 tons ≦Bv 01.93TiBto < f, Q4TΔ1. '/2
T 5 Bto < 1. Q3 T's 'fufu' power 0 actually the archer t is a fraud (002 Fig. 3, 100,000 o'c 耘lI!Shioin Ide elapsed time (S) Fig. 4 oMA'%A om4s Δ4fAt%c 750 '〜too°謬/lO Rudder Guard Room (S) Fu No. 5
Temperature during drawing (°C) * 1 mass R81, 22 pi C/l temperature, 2 rounds closed, 1 ■ Kaori l rolling, 4' g 1 off, 5 f to KH r no 4! Way H1 Figure 6 (a) D (f)) RI')

Claims (1)

[Claims] 1. C: 0.025 to 0.085 wt% Si: 2.0 to 4.0 wt% Mn: 0.01 to 0.20 wt% At least one of S and Se: 0.008 to 0.100wt% solAl: 0.010-0.065wt% and N:
A steel slab containing Zn: 0.003 to 0.013 wt%, Zn: 0.001 to 0.30 wt%, and the remainder having a composition of substantially Fe is heated, hot rolled, and then In a method for producing a grain-oriented silicon steel sheet, which comprises a series of steps of cold rolling two times or intermediate annealing to achieve the final thickness, decarburizing annealing, and final finish annealing, i) a slab; When heating, the residence time in the high temperature range of 1200°C or higher is within 70 minutes, and the heating is performed to a temperature of 1400°C or higher. ii) The annealing immediately before the final cold rolling is carried out at 900°C or higher.
At a temperature of 1200°C for 10 to 300 seconds, and at the same time as cooling from 750°C to 100°C at 175°C.
A method for producing a unidirectional silicon steel sheet with excellent magnetic properties characterized by a manufacturing time of within seconds. 2. C: 0.025-0.085 wt% Si: 2.0-4.0 wt% Mn: 0.01-0.20 wt% At least one of S and Se: 0.008-0.100 wt% solAl: 0.010-0.065wt%N: 0.0
A steel slab containing Zn: 0.03 to 0.013 wt% and Mo: 0.003 to 0.030 wt%, and Zn: 0.001 to 0.30 wt%, with the remainder being substantially Fe, is heated. A unidirectional silicone material consisting of a series of steps of hot rolling, then cold rolling once or twice with intermediate annealing to give the final thickness, followed by decarburization annealing and final finish annealing. In the method for manufacturing a steel plate, i) heating the slab to a temperature of 1400°C or higher with a residence time in a high temperature range of 1200°C or higher within 70 minutes; ii) annealing immediately before the final cold rolling to a temperature of 900°C or higher;
A method for manufacturing a grain-oriented silicon steel sheet with excellent magnetic properties, characterized by cooling at a temperature of 1200°C for 10 to 300 seconds and cooling from 75°C to 100°C within 175 seconds.