JP2002212635A - Method for producing grain oriented silicon steel sheet having excellent magnetic property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a grain oriented silicon steel sheet without changing decarburizing annealing conditions (particularly, annealing temperature) by solving the point at issue in the conventional superhigh temperature heating method. SOLUTION: A silicon steel slab having a composition containing, by mass, 0.01 to 0.10% C, 2.5 to 4.5% Si, 0.015 to 0.035% Al, 0.003 to 0.008% N, 0.02 to 0.15% Cu and 0.007 to 0.025% Se, and the balance Fe with inevitable impurities is heated at 1,200 to 1,350 deg.C in which AlN is made into solid solution, and is then hot-rolled. Next, the steel sheet is subjected to hot rolled sheet annealing, is thereafter subjected to cold rolling for one time or two or more times including process annealing, is subsequently subjected to decarburizing annealing, and is coated with a separation agent for annealing essentially consisting of MgO. Next, secondary recrystallization, glass film deposition and purification are caused in a box annealing furnace, and, the steel sheet is then subjected to heat treatment for modifying its shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a grain-oriented silicon steel sheet, and more particularly to a method for producing a grain-oriented silicon steel sheet with low iron loss and high magnetic flux density at low cost.

[0002]

2. Description of the Related Art A grain-oriented silicon steel sheet is mainly used as an iron core material for transformers and other electric equipment, and is required to have excellent magnetic properties such as magnetic flux density and iron loss value. In order to manufacture this unidirectional silicon steel sheet, a generally adopted method is to reheat a slab having a thickness of 100 to 300 mm, then hot-roll the slab, and apply the obtained hot-rolled sheet once or in the middle. The final thickness is obtained by cold rolling two or more times with annealing, and after decarburization annealing, an annealing separating agent is applied, and then the formation of a glass film mainly composed of forsterite, secondary recrystallization and purification are performed. It is common to carry out the desired finish annealing.

That is, first, a slab is heated at a high temperature to completely dissolve the inhibitor component, followed by hot rolling, one or more times of cold rolling and one or more times of annealing. The primary recrystallized grain structure obtained by the above method is controlled, and then the primary recrystallized grain # 11 is subjected to finish annealing.
The necessary magnetic properties are ensured by secondary recrystallization into crystal grains having a 0｝ <001> orientation.

In order to effectively promote such secondary recrystallization, first, a dispersed phase called an inhibitor for suppressing normal growth of primary recrystallized grains is uniformly and appropriately sized in steel. It is important to control the precipitation state so as to disperse the particles and to make the primary recrystallized grain structure uniform in size and uniform in size throughout the plate thickness.

As typical examples of such inhibitors, substances such as sulfides, selenides and nitrides such as MnS, MnSe, AlN and VN, which have extremely low solubility in steel, are used. Also, Sb, Sn, A
Grain boundary segregation elements such as s, Pb, Ce, Cu and Mo are also used as inhibitors. The method of using AlN as a main inhibitor in the production of a unidirectional silicon steel sheet is roughly classified into two methods. One is a method of completely dissolving the inhibitor in the slab heating step as described in Japanese Patent Publication No. 40-15644. In this method, since the temperature in the slab heating furnace is inevitably non-uniform, it is essential to dissolve the inhibitor in at least half of the slab thickness direction at the slab lowest temperature position. For this reason, in the actual operation, an ultra-high-temperature slab heating is performed or a special device for uniform slab heating is required. Therefore, adverse effects such as generation of slag and cracks at the ends of the hot-rolled steel sheet, which have been hitherto called, occur, and a large capital investment is required.

Another one is disclosed, for example, in JP-A-59-565.
As described in Japanese Patent Publication No. 22, the slab is heated not to form a solid solution at the slab heating stage, but to be positively precipitated. ). In this case, since the slab heating temperature can be lowered, there is no difficulty associated with the above-mentioned high-temperature superheating, but the strength of the primary inhibitor (inhibitor that determines the primary recrystallized grain size after decarburization annealing) is weak, so that good GOSS is achieved. In order to obtain the orientation texture, it is necessary to change the temperature in the decarburizing annealing to adjust the primary recrystallized grain system, and the nitrogen content at the time of the final annealing in which the glass film is formed is increased by the solid solution. The quality of the glass film may not be stable because the amount is larger than in the case of the method.

As described above, the Al-containing unidirectional silicon steel sheet has excellent magnetic properties, but has great difficulties in actual industrial production. In any case, in order to obtain a good secondary recrystallization structure, it is important to control the inhibitor from the precipitation of the inhibitor element in the hot rolling to the subsequent secondary recrystallization annealing. It is a requirement, and it can be said that such inhibitor control becomes more and more important in order to secure better magnetic properties.

[0008] By the way, in the solid solution method, from the viewpoint of inhibitor control, as a conventional technique focusing on the temperature history from finish rolling to winding in a hot rolling step, for example,
JP-B-38-14409, JP-A-56-3343
No. 1, JP-A-59-50118, JP-A-64
-73023, JP-A-2-263924,
JP-A-4-323, JP-A-2-274811, and JP-A-5-295442 are known.

Japanese Patent Application Laid-Open No. 56-33431 discloses a method of controlling the winding temperature to a temperature range of 700 to 1000 ° C.
Method of keeping heat for minutes to 5 hours, and 700 to 1000 ° C
A method of quenching the coil after high-temperature winding is disclosed. This technique is a method of improving the precipitation and dispersion of AlN as an inhibitor. However, non-uniform decarburization proceeds due to self-annealing in the coil shape after winding, and the formation of the cold rolled texture is also unstable. And the variation in product characteristics becomes large. In particular, water cooling or the like in a coil shape causes unevenness in the cooling rate, thereby causing variations in product characteristics.

Japanese Unexamined Patent Publication (Kokai) No. 59-50118 discloses the following (1) after finishing a hot-rolled steel strip and leaving the final stand.
A method of cooling at a cooling rate of 7 to 40 ° C./sec to a temperature range calculated from the formula (2), and then winding and cooling the hot rolled steel strip. A method of cooling at a temperature of 7 to 30 ° C./sec below the temperature calculated from the equation (3), winding, and further cooling the wound steel strip with water is disclosed.

(35 × logV + 515) ° C. (1) (445 × logV-570) ° C. (2) (20 × logV + 555) ° C. (3) [However, V: Cooling rate of hot-rolled steel strip from leaving the final finishing stand to winding it up (° C./sec)] However, this technique is applicable when AlN is not used as an inhibitor.

In Japanese Patent Application Laid-Open No. 2-263924, C: 0.02 to 0.100% by mass%, Si: 2.
Containing 5-4.5% as well as the usual inhibitor components,
The remainder is hot-rolled with a silicon steel slab composed of Fe and unavoidable impurities, and without a hot-rolled sheet annealed, a reduction rate of 8
In a method for producing a unidirectional silicon steel sheet by performing cold rolling, decarburizing annealing, and final finish annealing of 0% or more, the hot rolling end temperature is set to 750 to 1150 ° C, and at least 1 second or more, 700 ° C after the end of hot rolling. The above temperature is maintained and the winding temperature is 700
A technique for lowering the temperature to less than ° C is disclosed.

From the viewpoint of cost reduction, this technique is intended to promote recrystallization by maintaining a high temperature after finish rolling, improve the structure, and omit hot rolled sheet annealing. By promoting the recrystallization after hot rolling by this technique, the structure is improved and the annealing of the hot rolled sheet can be omitted, but a better inhibitor precipitation state has not yet been obtained as compared with the prior art. In addition, this technique has a problem in that the control of inhibitor precipitation must be sacrificed because the hot-rolled sheet annealing is omitted.

In Japanese Patent Laid-Open No. 2-74811, C: 0.021 to 0.075% by mass, Si:
2.5-4.5%, acid-soluble Al: 0.010-0.0
60%, N: 0.0030 to 0.0130%, S + 0.
405Se: 0.014% or less, Mn: 0.05-0.
A slab containing 8% and the remainder consisting of Fe and unavoidable impurities is heated at a temperature of less than 1280 ° C., then hot-rolled, and subsequently, if necessary, hot-rolled sheet annealing, and then a reduction of 80%. % Or more, including one or more final cold rollings, and if necessary, one or more cold rollings with intermediate annealing.
In the method for producing a grain-oriented silicon steel sheet by performing decarburizing annealing and final finishing annealing, the hot rolling end temperature is set to 750 to 115.
A technique is disclosed in which the temperature is set to 0 ° C., the temperature is maintained at 700 ° C. or higher for at least 1 second or more after completion of hot rolling, and the winding temperature is set to less than 700 ° C.

This technique aims to promote recrystallization by maintaining a high temperature after finish rolling in a manufacturing process in which low-temperature slab heating is performed, thereby improving and stabilizing magnetic properties. However, in low-temperature slab heating, Al
Since N does not form a solid solution sufficiently and the precipitation behavior of AlN fluctuates depending on the position of the steel sheet, it is impossible to stably produce a product having excellent magnetic properties. That is, in the step of performing low-temperature slab heating, there is a problem in that the control of the inhibitor in slab heating and hot rolling is ineffective, so that a product having excellent magnetic properties cannot be stably manufactured.

Also, Japanese Patent Application Laid-Open No. Hei 8-100216 discloses that
Cooling conditions for hot rolling when AlN is used as the main inhibitor are specified, and the content of Cu is also described, but its effect is not described and Cu is not essential.

[0017]

What is common to the above-mentioned prior arts is that, in the production of a unidirectional silicon steel sheet using AlN as a main inhibitor, an ultra-high-strength inhibitor is required in order to ensure a good inhibitor function. High temperature slab heating (1350 ° C
Or a substantial problem such as a glass film defect due to the nitriding treatment.

Therefore, the present inventors have studied the inhibitors in various ways and have found that even if the slab heating temperature is not an ultra-high temperature and the decarburization annealing temperature is not changed, the unidirectional electrical steel sheet can be stably produced. We tried to find a way to manufacture it. Mn as an auxiliary inhibitor in the production of a grain-oriented silicon steel sheet using AlN as the main inhibitor
The method using S, Cu ₂ S and MnSe is a solid solution method.
For example, it is disclosed in JP-A-58-217630, and the precipitation method is disclosed in JP-A-7-204781. Instead of these, the present inventors have found that a copper selenium compound is effective as an auxiliary inhibitor, and have completed the present invention.

[0019]

Means for Solving the Problems (1) C: 0.01 to
0.10% by mass, Si: 2.5 to 4.5% by mass, Al:
0.015 to 0.035 mass%, N: 0.003 to 0.
008% by mass, Cu: 0.02 to 0.15% by mass, S
e: A silicon steel slab containing 0.007 to 0.025% by mass, the balance being Fe and inevitable impurities was 1200
After heating to a temperature at which AlN of not less than 1350 ° C. and not more than 1350 ° C. is solid-dissolved, hot-rolled, and then subjected to hot-rolled sheet annealing,
Perform cold rolling once or twice or more with intermediate annealing, then perform decarburizing annealing, apply an annealing separator containing MgO as a main component, and then perform secondary recrystallization in a box-type annealing furnace.
A method for producing a unidirectional silicon steel sheet having excellent magnetic properties, characterized by forming a glass film, purifying the glass film, and then performing a heat treatment for shape correction.

(2) The ratio of Se and S in the silicon steel slab is 1/18 (0.215-5 [Se]) ≦ [S] ≦ 1/1
8 (0.430-10 [Se]) (where [Se],
[S] is% by mass.] (1) The method for producing a unidirectional silicon steel sheet having excellent magnetic properties according to (1).

(3) The finish rolling finish temperature of the hot rolling is in the range of 900 to 1100 ° C., and the cooling from the completion of the finish rolling to the winding is represented by the following formula: T (t) <FDT- (FDT-700) ) × t / 6 2 ≦ t ≦ 6 [where T (t): steel sheet temperature (° C.), FDT: finish rolling finish temperature (° C.), t: elapsed time from finish finish of hot rolling (second) And (2) the method of producing a unidirectional silicon steel sheet having excellent magnetic properties.

(4) As a component of the silicon steel slab,
Further, the method for producing a unidirectional silicon steel sheet having excellent magnetic properties according to any one of (1) to (3), wherein Mn is contained in an amount of 0.02 to 0.10% by mass. (5) The unidirectional silicon steel sheet having excellent magnetic properties according to any one of (1) to (4), wherein the average grain size of the primary recrystallized grains after completion of the decarburizing annealing is set to 7 μm or more and less than 18 μm. Manufacturing method.

(6) As a component of the silicon steel slab,
Further, at least one of Sn, Sb, and P may
(1)-characterized by containing 0.30% by mass.
(5) The method for producing a unidirectional silicon steel sheet having excellent magnetic properties according to any of (5). (7) As a component of the silicon steel slab, Cr
(1) to (6), characterized by containing 0.02 to 0.30% by mass.

(8) As a component of the silicon steel slab,
Further, the method for producing a unidirectional silicon steel sheet excellent in magnetic properties according to any one of (1) to (7), wherein Ni is contained in an amount of 0.03 to 0.30% by mass. (9) As a component of the silicon steel slab, M
(1) The method for producing a grain-oriented silicon steel sheet having excellent magnetic properties according to (1) to (8), wherein at least one of Cd and 0.005% by mass is contained.

(10) In the steel sheet annealing just before the final cold rolling in the cold rolling, the annealing temperature is set to 950 to 950.
(1) The method for producing a grain-oriented silicon steel sheet having excellent magnetic properties according to any one of (1) to (9), wherein the annealing time is 30 seconds or more and 600 seconds or less. (11) The rolling rate of the final cold rolling in the cold rolling is set to 80 to 92% (1) to (1).
0) The method for producing a grain-oriented silicon steel sheet having excellent magnetic properties according to any one of (1) and (2).

(12) In at least one pass of the final cold rolling in the cold rolling, a steel sheet is
It is characterized in that it is kept in a temperature range of 0 ° C. for 1 minute or more (1).
A method for producing a unidirectional silicon steel sheet having excellent magnetic properties according to any one of (1) to (11).

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The most significant features of the present invention are the following two points. First, AlN used as an inhibitor
Not only that, by containing Cu and Se, an inhibitory effect of the copper selenium compound Cu—Se was found.

Next, it has been found that the magnetic property defect (mainly a so-called skit mark) which occurs due to the non-uniform temperature of the heating furnace in the conventional hot rolling mainly occurs due to the difference in the degree of solid solution of AlN. Further, when the content of the counter elements S and Se is small, the Mn-based and Cu-based precipitates are finely precipitated in small amounts, resulting in poor magnetic properties. However, within the scope of the present invention, secondary recrystallization occurs. Has not been affected.

Further, it has been found that the magnetic properties are further improved by the inhibitor complex and the nitriding before the start of the secondary recrystallization after the decarburizing annealing. Hereinafter, the present invention will be described in detail. The present inventors have conducted a detailed study for realizing the above-mentioned object, and as a result, in the Al-containing unidirectional silicon steel sheet, Cu-Se is used to secure GOSS orientation grains in the production of the unidirectional silicon steel sheet. Have a very large auxiliary inhibitor effect. of course,
The inhibition effect (grain growth suppression effect) of Cu-Se is described in CAMP-ISIJ Vol. 3 (1990) -1837, but the material in this document does not contain Al, and furthermore, No mention is made of the magnetic properties of the unidirectional silicon steel sheet.

As a result of the study, the present inventors have found that AlN forms a solid solution at the time of slab heating, forms a solid solution in a hot-rolled sheet, and finely precipitates by continuous annealing before final cold rolling. Even if the precipitation of the alloy is somewhat uneven,
It has been found that even if the primary recrystallization temperature is changed from 810 ° C to 900 ° C, the grain size after the primary recrystallization annealing does not change significantly. Conversely, if AlN is not completely dissolved in hot rolling at the time of reheating in hot rolling and the solid solution in hot rolling is insufficient, the particle size of the decarburizing annealing / primary recrystallization temperature fluctuates.

In other words, it can be seen that AlN which has been dissolved once and then finely precipitated has a very strong primary inhibitor effect even if there is no amount for providing both primary and secondary inhibitor functions in the prior art. I found it. But,
It is not possible to stably obtain the secondary recrystallized GOSS orientation in the grain-oriented electrical steel sheet only with this fine AlN.

In order to stably obtain the secondary recrystallization of the GOSS orientation in a unidirectional silicon steel sheet, the present inventor uses the fine AlN as a main inhibitor and uses a selenide of Cu as an auxiliary inhibitor. It has been found that good GOSS secondary recrystallization can be obtained. Cu-Se has a very high deposition rate after solid solution, and is preferentially precipitated when Mn is small. In addition, they have found that this Cu-Se is effective as an auxiliary secondary inhibitor of AlN. It is presumed that the reason for this is that the precipitate size is larger than MnS and is uniform and thermally stable.

The reason why the slab heating temperature is set to 1200 to 1350 ° C. is that if the temperature is less than 1200 ° C., the solid solution of AlN becomes non-uniform. When the temperature exceeds 1350 ° C., the operation of the heating furnace for hot rolling becomes an extremely high temperature, and there are various difficulties conventionally known. In this temperature range, it is estimated that the presence of Cu lowers the solid solution temperature of the Mn compound, and as a result, the precipitation of the inhibitor becomes more uniform than in the case of the Mn compound alone. In addition, a preferable heating temperature range is 1250 to
1315 ° C.

This uniformly precipitated Cu—Se reinforces AlN as a secondary inhibitor during secondary recrystallization annealing,
Good magnetic properties can be obtained by promoting preferential growth of GOSS ({110} <001>) oriented grains. The reason why the finish rolling end temperature (FDT) was set to 900 to 1100 ° C. was 900
If the temperature is lower than 1 ° C., undesirable inhibitor precipitation occurs in the finishing rolling stand, and if the temperature is higher than 1100 ° C., it becomes extremely difficult to achieve both passing and cooling.
The preferred finish rolling end temperature range is 950 to 10
00 ° C.

The reason why the winding temperature is set to 700 ° C. or less is as follows.
At a high temperature exceeding 700 ° C., AlN precipitates due to self-annealing after winding, resulting in poor magnetic properties. In addition, the preferable winding temperature range is 500-600 degreeC. That is, the reason for defining the temperature history from the finish rolling of hot rolling to winding up is to sufficiently dissolve the solid solution without precipitating AlN in the specified range. If it is slower than the specified range, it precipitates during hot rolling and the magnetic properties become poor.

The reason why such an effect can be obtained by the temperature history after the completion of the finishing hot rolling is apparent. This is because AlN of the added inhibitor component is made almost completely solid solution by hot rolling and precipitation of Cu-Se is made more uniform. Therefore, it is basically important to shorten the high-temperature residence time immediately after finishing hot-rolling in order to obtain a favorable inhibitor precipitation form.

In the present invention, other than the conditions described above,
The production conditions in each of the steps such as hot rolling, hot rolled sheet annealing, pickling, intermediate annealing, cold rolling, decarburizing annealing, application of an annealing separator, and finish annealing may be performed according to known methods. As the silicon-containing steel which is a material of the present invention, a steel containing a combination of AlN and Cu-Se as an inhibitor mainly suitable from the molten steel stage. The component composition is as follows.

C: 0.01 to 0.10% by mass C is an element useful not only for making the composition uniform and fine during hot rolling and cold rolling, but also for developing the Goss orientation. It is necessary to contain the content by mass%. However, 0.
If the content exceeds 10% by mass, decarburization becomes difficult and the Goss orientation is rather disturbed. Therefore, the upper limit is 0.10% by mass.
And In addition, preferable C content is 0.03-0.08.
% By mass.

Si: 2.5 to 4.5% by mass Si increases the specific resistance of the steel sheet and contributes to a reduction in iron loss.
When the Si content is less than 2.5% by mass, the effect of reducing iron loss is not sufficient, and in the finish annealing at a high temperature performed for purification and secondary recrystallization, randomization of crystal orientation due to α-γ transformation. And sufficient magnetic properties cannot be obtained. On the other hand, if it exceeds 4.5% by mass, the cold rollability is impaired, and the production becomes difficult. Therefore, the Si content is 2.5 to
It is set to 4.5% by mass. Preferably, 3.0 to 3.7.
% By mass.

Mn: 0.02 to 0.10% by mass Mn is inevitably present in molten steel.
Is used as a main inhibitor and is not essential as an inhibitor element. However, Mn is an effective element for preventing cracking during hot rolling due to hot embrittlement,
The effect cannot be obtained at less than 0.02% by mass. on the other hand,
If it is added in excess of 0.10% by mass, it does not form a solid solution at the time of slab heating, which causes a change in magnetic properties and deteriorates the properties. Therefore, the Mn content is set to 0.02 to 0.10% by mass. In addition, it is preferably in the range of 0.03 to 0.07% by mass.

Al: 0.015 to 0.035% by mass Al is an element that forms AlN and acts as an inhibitor. If the Al content is less than 0.015% by mass, the suppression power is not sufficiently ensured.
If the content exceeds 1, the effect is impaired. Therefore, the Al content is set to 0.015 to 0.035% by mass. In addition, a preferable range is 0.024 to 0.030 mass%.

N: 0.003 to 0.008% by mass N is an element that forms AlN and acts as an inhibitor. In the present invention, AlN needs to be completely dissolved in the slab during heating, so that the balance with Al is limited. If the N content is less than 0.003% by mass, the suppression force is not sufficiently secured, and the magnetic properties are deteriorated due to poor secondary recrystallization. On the other hand, when the content exceeds 0.01% by mass, blister defects (swelling) occur, but the content is 0.008% by mass since Al forms a solid solution within the above range. Note that a preferable range is 0.004 to 0.006% by mass.

Se: 0.007 to 0.025% by mass alone Se is a powerful element that forms Cu—Se to act as an inhibitor. Se content is 0.00
If the amount is less than 7% by mass, a small amount of fine particles is precipitated, and the suppression force is not secured uniformly.

S: an amount satisfying the following formula: S is a powerful element that forms MnS and acts as an inhibitor conventionally. In the case of the present invention, S has the effect of complementing Se, but if it is too large, it forms MnS. Do not form a solid solution. 1/18 (0.215-5 [Se]) ≦ [S] ≦ 1/1 in balance with Se
8 (0.430-10 [Se]) (where [Se],
[S] is mass%). Of course, S is inevitably contained in molten steel in an amount of about 0.003% by mass, so that it is practically a complex content. Cu: 0.02 to 0.15% by mass Cu is very important as an auxiliary inhibitor in the present invention, and if it is less than 0.02% by mass, there is no inhibitory effect as Cu—Se. On the other hand, if it exceeds 0.15% by mass, the surface of the steel sheet tends to have flaws. Therefore, Cu
The content is set to 0.02 to 0.15% by mass.

In the present invention, Sn, Sb, P, and Cr act as an inhibitor component in addition to the above-mentioned elements, so that they can be contained together with the above components. The preferable addition range of these components is 0.02 to 0.30% by mass, respectively. Furthermore, N
i is 0.03 to 0.30 mass%, Mo and Cd are 0.00
The effect is effective at 5 to 0.30% by mass.

[0046]

EXAMPLE 1 Example 1 has the chemical composition shown in Table 1, and the balance is substantially 200 mm in thickness and 1000 mm in width made of Fe.
Silicon steel continuous casting slab of 130
1. At 0 ° C., the AlN is heated to form a solution and hot rough rolling is performed, followed by hot finishing rolling at a rolling end temperature of 950 ° C.
The thickness was adjusted to 3 mm, and then controlled and cooled at each temperature history shown in FIG.

This hot-rolled sheet was subjected to hot-rolled sheet annealing at 980 ° C. × 3 minutes and pickling, and then cold-rolled to an intermediate sheet thickness of 1.55 mm, and intermediate annealing at 1120 ° C. × 45 seconds. Later, 0.
It was cold rolled to a final thickness of 23 mm. Next, the obtained cold-rolled sheet is subjected to decarburizing annealing at 850 ° C. for 2 minutes in a wet hydrogen atmosphere, and then an annealing separator containing MgO as a main component is applied, and the atmosphere is subjected to an atmosphere of 25% nitrogen and 75% hydrogen. 900-1 in
Secondary recrystallization at a heating rate of 15 ° C./hour between 100 ° C.,
Thereafter, final finishing purification annealing was performed at 1200 ° C. for 20 hours in a hydrogen atmosphere, and thereafter, an insulating film having shape correction and tension was applied to obtain a finished product. The magnetic properties of the obtained product were measured. Table 2 shows the results.

As shown in Table 2, according to the method of the present invention, it can be seen that all of them show excellent magnetic properties such as high magnetic flux density and low iron loss. On the other hand, it can be seen that the magnetic properties of the comparative examples outside the range of the present invention are inferior.

[0049]

[Table 1]

[0050]

[Table 2]

Example 2 Having the chemical composition shown in Table 3,
The balance is substantially 250 mm in thickness and 1000 mm in width made of Fe.
mm continuous cast silicon steel slab in a normal gas heating furnace.
After heating at 90 ° C. to form a solution of the inhibitor component and hot rough rolling, hot finishing rolling at a rolling end temperature of 950 ° C. was performed to a thickness of 2.3 mm, and then the temperature history of A and B shown in FIG. Controlled cooling and winding at 560 ° C.

The hot rolled sheet was annealed (1120 ° C.,
(90 seconds), and after pickling, rolled to a final sheet thickness (0.29 mm) at a temperature of 180 ° C to 250 ° C. Next, the obtained cold-rolled sheet is subjected to decarburizing annealing at 850 ° C. for 3 minutes in a wet hydrogen atmosphere, and then an annealing separating agent containing MgO as a main component is applied, and an atmosphere of 25% nitrogen and 75% hydrogen is applied. 900 in
The secondary recrystallization is performed at a heating rate of 10 ° C./hour 15 ° C./hour between −1100 ° C. and 1200 ° C. in a hydrogen atmosphere.
The product was subjected to final finishing purification annealing for 20 hours, and thereafter, an insulating film having shape correction and tension was applied to obtain a finished product. The magnetic properties of the obtained product were measured. Table 4 shows the results.

As shown in Table 4, according to the method of the present invention, it can be seen that all of them show excellent magnetic properties such as high magnetic flux density and low iron loss. On the other hand, it can be seen that the magnetic properties of the comparative examples outside the range of the present invention are inferior.

[0054]

[Table 3]

[0055]

[Table 4]

[0056]

As described above, according to the present invention, in the production of a unidirectional silicon steel sheet using a combination of AlN and Cu-Se as an inhibitor, the problem of the ultra-high temperature heating which the conventional method has had. And the conditions of decarburization annealing,
In particular, there is no need to change the annealing temperature, and it is possible to manufacture a unidirectional silicon steel sheet having excellent magnetic properties.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cooling history after finishing rolling of hot rolling.

Continued on the front page (72) Inventor Noriyoshi Fujii 1-1 Niwahata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture Nippon Steel Corporation Yawata Works (72) Inventor Yoshifumi Ohata Tobihata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka 1-1 Nippon Steel Corporation Yawata Works (72) Inventor Katsuro Kuroki 59-46 Nakahara, Tobata-ku, Kitakyushu-shi, Fukuoka F-term (reference) 4K033 AA02 BA02 CA01 CA02 CA03 CA04 CA07 CA08 DA01 FA01 FA03 FA10 FA12 HA01 HA03 JA04 LA01 MA00 MA02 RA04 SA02 5E041 AA02 AA19 CA02 HB11 NN01 NN06 NN18

Claims (12)

[Claims] 1. C: 0.01 to 0.10% by mass, Si:
2.5 to 4.5% by mass, Al: 0.015 to 0.035
% By mass, N: 0.003 to 0.008% by mass, Cu:
0.02 to 0.15 mass%, Se: 0.007 to 0.0
A silicon steel slab containing 25% by mass, the balance being Fe and inevitable impurities, is heated to a temperature at which AlN of 1200 ° C. or more and 1350 ° C. or less is dissolved, then hot-rolled, and then hot-rolled sheet annealing is performed. After that, cold rolling is performed once or twice or more with intermediate annealing, followed by decarburizing annealing, applying an annealing separator containing MgO as a main component, and then using a box-type annealing furnace. A method for producing a unidirectional silicon steel sheet having excellent magnetic properties, characterized by causing secondary recrystallization, glass film formation and purification, and then performing a heat treatment for shape correction. 2. The ratio of Se and S in the silicon steel slab is 1/18 (0.215-5 [Se]) ≦ [S] ≦ 1/1.
8 (0.430-10 [Se]) (where [Se],
The method for producing a unidirectional silicon steel sheet having excellent magnetic properties according to claim 1, wherein [S] is mass%. 3. The finish rolling end temperature of the hot rolling is 9
In the range of 00 to 1100 ° C., and the cooling from the finish rolling to the winding after the end of the finish rolling is represented by the following formula: T (t) <FDT− (FDT−700) × t / 6 2 ≦ t ≦ 6 [where T (t ): Steel sheet temperature (° C.), FDT: finish rolling finish temperature (° C.), t: elapsed time (seconds) from finish rolling of hot rolling] and winding at 700 ° C. or less. The method for producing a unidirectional silicon steel sheet having excellent magnetic properties according to claim 1 or 2. 4. The magnetic property according to claim 1, wherein the silicon steel slab further contains Mn in an amount of 0.02 to 0.10% by mass. A method for producing a unidirectional silicon steel sheet. 5. The magnetic material according to claim 1, wherein an average particle diameter of primary recrystallized grains after completion of the decarburizing annealing is 7 μm or more and less than 18 μm. A method for producing a grain-oriented silicon steel sheet. 6. The composition of the silicon steel slab further comprises at least one of Sn, Sb, and P in an amount of 0.02-0.
The method for producing a grain-oriented silicon steel sheet having excellent magnetic properties according to any one of claims 1 to 5, characterized by containing 30% by mass. 7. The magnetic material according to claim 1, further comprising 0.02 to 0.30% by mass of Cr as a component of the silicon steel slab. A method for producing a unidirectional silicon steel sheet. 8. The magnetic properties according to claim 1, wherein the silicon steel slab further contains Ni in an amount of 0.03 to 0.30% by mass. A method for producing a unidirectional silicon steel sheet. 9. The silicon steel slab further contains at least one of Mo and Cd in an amount of 0.005 to 0.3.
The method for producing a grain-oriented silicon steel sheet having excellent magnetic properties according to any one of claims 1 to 8, characterized by containing 0% by mass. 10. The steel sheet annealing just before final cold rolling in said cold rolling, wherein the annealing temperature is 950-11.
The method for producing a grain-oriented electrical steel sheet according to any one of claims 1 to 9, wherein the annealing temperature is 50 ° C and the annealing time is 30 seconds or more and 600 seconds or less. 11. The rolling rate of final cold rolling in the cold rolling is set to 80 to 92%.
10. The method for producing a unidirectional silicon steel sheet having excellent magnetic properties according to any one of items 10 to 10. 12. The steel sheet is maintained in a temperature range of 100 to 300 ° C. for at least one minute in at least one pass of final cold rolling in the cold rolling.
A method for producing a unidirectional silicon steel sheet having excellent magnetic properties according to any one of the above items.