JPH0533056A - Production of grain-oriented silicon steel sheet excellent in magnetic property - Google Patents

Abstract

PURPOSE:To improve magnetic properties by specifying roll diameter and conditions at the time of final cold rolling, respectively, in a method for subjecting a steel slab to hot rolling, to cold rolling where rapid cooling and rolling are done after continuous annealing, to decarburizing annealing, and to final finish annealing. CONSTITUTION:A slab of a steel having a composition containing, by weight, 0.02-0.10% C, 2.5-4.5% Si, 0.05-0.15% Mn, 0.01-0.04% Sb, and further 0.01-0.04% Se and/or 0.01-0.04% S is hot-rolled and cooled rapidly at least before final cold rolling and after continuous annealing at 900-1150 deg.C. Subsequently, this steel stock is cold-rolled once or twice or more, where rolling is made at 40-90% draft. The resulting, steel sheet is subjected to decarburizing annealing and then to final finish annealing, by which a grain-oriented silicon steel sheet can be obtained. In this method, final cold rolling is by plural passes by means of small-diameter rolls of 50-150mm diameter at 150-350 deg.C in the former stage until 30% of the total draft is reached and at <150 deg.C in the remaining latter stage. By this method, the balance between the (110)<001> orientation and the (111)<112> orientation in the texture can be properly regulated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of magnetic properties in grain-oriented silicon steel sheets mainly used as core materials for transformers and other electric equipment.

As an iron core material of this kind of electric equipment, it has excellent magnetic properties, specifically, high magnetic flux density B ₈ (T) at a magnetic field strength of 800 A / m, and AC magnetic flux density of 1.7 T at 50 Hz. The iron loss characteristic W _17/50 (W / kg) in is required to be low. For this reason, the grain-oriented silicon steel sheet is one in which crystal grains of {110} <001> orientation, so-called Goss orientation, are developed by utilizing secondary recrystallization. In order to obtain a material with excellent magnetic properties, it is necessary to align the <001> axis, which is the easy axis of magnetization, to a high degree in the rolling direction by secondary recrystallization after going through various steps that combine appropriate rolling and heat treatment. is important. Especially MnS, MnSe, AlN called inhibitors
Uniformly and finely disperse precipitates such as
It has already been known that it is essential to have a texture that is advantageous for secondary recrystallization.

[0003]

2. Description of the Related Art As a method for obtaining a texture advantageous for secondary recrystallization, for example, the roll diameter is changed in the latter half of the final cold rolling.
To be less than 300 mm (see Japanese Patent Laid-Open No. 49-34417)
Is widely used for cold rolling of grain-oriented silicon steel sheets.
This is because the cold rolling of the grain-oriented silicon steel sheet, that is, the slightest change in the recrystallization texture has a great influence on the magnetic properties.

Similarly, regarding cold rolling of grain-oriented silicon steel sheets, Japanese Patent Laid-Open Nos. 54-71028 and 57-73127 disclose that special rolls such as grooved rolls and dull rolls are used for cold rolling. Has been proposed, and in JP-A-61-238916,
It has been proposed to use CBS rolling. All of these methods can be expected to have the effect of strongly accumulating sharp {110} <001> oriented grains, but are unsuitable for actual operation in terms of roll wear, rolling shape and productivity. Further, it is difficult to obtain a proper texture, and there is a disadvantage that the magnetic flux density is often significantly reduced due to the refinement of the secondary recrystallized grain size.

Japanese Patent Publication No. 50-26493 and Japanese Patent Laid-Open No. 60-12
No. 1223 discloses that in cold rolling, 50 to 350 ° C or
It has been shown that by performing rolling in the temperature range of 50 to 500 ° C., the slip that occurs during cold rolling is changed and a texture that is advantageous for secondary recrystallization is obtained. However, the above-mentioned warm rolling has technical problems such as instability of the rolling itself, and it takes more time to carry out than the effects obtained, so that it is difficult to apply it on an industrial scale. Further, JP-A-2-282422 proposes a method for producing a thin grain-oriented silicon steel sheet by combining a small diameter roll and warm rolling, and particularly performing warm rolling in the latter half of cold rolling. In the warm rolling in the latter half of the cold rolling, it is difficult to control the shape of the plate and recovery is likely to occur, so that a problem remains in a place where the appropriate temperature range is narrow.

[0006]

By the way, the presence of {110} <001> oriented grains is important for the texture advantageous for secondary recrystallization, and the texture of the matrix eroded by these crystal grains is also extremely large. is important. Especially {110} <00
There is a good correspondence between the 1> orientation and the {111} <112> orientation, and the growth behavior of the secondary recrystallized grains may depend on how to balance the two. The above-mentioned conventional technique has an unstable orientation of {110} <00 in the cold rolling process.
I am concerned about how to store 1> oriented grains, but at the same time, if I do not properly balance with {111} <112> oriented grains, secondary recrystallization becomes unstable and {110} <00
1> The effect of storing the oriented grains cannot be effectively used. Therefore, an object of the present invention is to solve the above problems and propose a method capable of advantageously producing a grain-oriented silicon steel sheet having excellent magnetic properties.

[0007]

The present invention provides C: 0.02 to
0.10wt% (hereinafter simply expressed as%), Si: 2.5-4.5%, M
n: 0.05 to 0.15% and Sb: 0.01 to 0.04%, and further S
e: 0.01 to 0.04% and S: 0.01 to 0.04% of a steel slab having a composition containing at least one of them is hot-rolled, and continuously at least in the temperature range of 900 to 1150 ° C before the final cold rolling. After annealing, rapid cooling followed by rolling in the range of 40 to 90%, one or more cold rolling, followed by decarburization annealing and final finishing annealing. In producing a raw steel sheet, the final cold rolling is performed in multiple passes using small diameter rolls with a diameter of 50 to 150 mm, and the former stage up to 30% of the total reduction is 150 to 350 ° C.
Is carried out in the temperature range of 1, and the rest of the subsequent steps are carried out in the temperature range of less than 150 ° C, which is a method for producing grain-oriented silicon steel sheet with excellent magnetic properties. In addition, this invention is further sol.Al: 0.
A method for producing a grain-oriented silicon steel sheet having excellent magnetic properties using a steel slab having a composition containing 01 to 0.06 wt% and N: 0.003 to 0.015 wt%.

The experimental results, which are the basis of the present invention, will be described in detail below. The inventors conducted experiments on the effect of warm rolling on secondary recrystallization. Experiment is C: 0.045
%, Si: 3.35%, Mn: 0.08%, Se: 0.018%, S: 0.01
A cold-rolled sheet having a sheet thickness of 0.78 mm after the intermediate annealing and containing 0% and Sb: 0.024% and the balance iron and inevitable impurities was used as a starting material. This cold-rolled sheet was cold-rolled in 4 passes to give a final sheet thickness of 0.27
In order to clarify the conditions under which warm rolling works most effectively for finishing to mm, warm rolling was performed for each pass. The warm rolling was carried out by heating immediately after heating at 300 ° C. for 2 minutes, and the roll diameter of the rolling mill was 100 mm. After warm rolling, decarburization annealing was performed at 820 ° C for 3 minutes in wet hydrogen, and then secondary recrystallization annealing was performed at 850 ° C for 50 hours and 1200 ° C for 5 hours in H ₂ atmosphere. The final finish annealing was performed. Table 1 shows the results of examining the magnetic properties of the obtained products.

[0009]

From the table, it can be seen that the steel sheet that has been subjected to warm rolling has superior magnetic properties to the steel sheet that has been subjected to only cold rolling.
It was found that No. 3 produced a steel sheet with superior properties, as compared with the case of all No. 2, in which it was warm-rolled.

Next, an experiment was conducted on optimization of the rolling roll diameter in warm rolling. The experiment is the same as the above experiment.
Warm rolling up to 60 mm was performed with rolls having a diameter of 100 mm, and then the remaining rolling was performed with rolls having various diameters. The results of examining the magnetic properties of the obtained product are shown in Table 2.

[0012]

From the results shown in the table, it is possible to bring out the effect of warm rolling with high efficiency by carrying out warm rolling in the preceding stage of final cold rolling and then rolling with a small diameter roll of 150 mm or less. I understand. The reason for this is not necessarily clear, but the result of X-ray diffraction shows that the warm rolling can significantly enhance the accumulation of the {111} <112> orientation without impairing the accumulation of the {110} <001> orientation. It is known from.

Further, an experiment was conducted on the temperature and the rolling reduction in the warm rolling. First, the experiment on the warm rolling temperature was as follows: C: 0.045%, Si: 3.32%, Mn: 0.07%, Se: 0.
A continuous cast slab containing 021% and Sb: 0.026% and the balance of iron and inevitable impurities was heated at 1430 ℃ for 15 minutes, and then the plate thickness was 2.7m.
m hot rolled sheet, then hot rolled sheet annealed at 1000 ℃ for 30s, then cold rolled to 0.78mm thickness at 60 ℃ at 1050 ℃
After the intermediate annealing of s, the second cold rolling was performed with a reverse mill having a roll diameter of 90 mm. Here, in the second cold rolling, the steel plate temperature was 50 to 400 by the induction heating device installed at the mill entrance.
Rolled to 0.55 mm thickness by changing to various temperatures in the range of ℃,
After that, it was cooled to room temperature with strip coolant and finished to a final plate thickness of 0.27 mm. 82 in wet hydrogen
After decarburization annealing at 0 ° C. for 3 minutes, final annealing was performed after applying an annealing separating agent containing MgO 2 as a main component. As a result of investigating the magnetic properties of the obtained product, as shown in FIG. 1, good magnetic properties were obtained with the steel sheet that was subjected to warm rolling in the temperature range of 150 to 350 ° C.

Next, an experiment on the rolling reduction of the warm rolling was carried out by C:
0.040%, Si: 3.35%, Mn: 0.07%, Se: 0.015%, S
b: 0.022%, Cu: 0.08%, S: 0.008% Continuous cast slab consisting of balance iron and unavoidable impurities was heated at 1430 ° C for 15 minutes to form a hot rolled sheet with a thickness of 2.7 mm, then at 1000 ° C for 30 minutes.
After the hot-rolled sheet of s was annealed, it was cold-rolled for the first time to a thickness of 0.78 mm, annealed for 60 s at 1050 ° C., and then cold-rolled for the second time by a reverse mill with a roll diameter of 120 mm. 2 here
For the second cold rolling, after the steel plate temperature was set to 250 ° C by the induction heating device installed at the mill inlet, rolling with various reduction ratios was performed, and then it was cooled to room temperature by strip coolant and then 0.27 mm Finished to the final plate thickness. After decarburization annealing in wet hydrogen at 820 ° C for 3 minutes,
After the annealing separator containing MgO as a main component was applied, final finish annealing was performed. As a result of examining the magnetic properties of the obtained product, as shown in FIG. 2, good magnetic properties were obtained with the steel sheet that had been subjected to warm rolling at a rolling reduction of 30% or less.

[0016]

The steel slab as the starting material of the present invention has a C: 0.02
~ 0.10%, Si: 2.5-4.5%, Mn: 0.05-0.15%, Sb:
0.01-0.04%, further Se: 0.01-0.04% and S:
A component composition containing 0.01 to 0.04% and a component composition containing sol.Al: 0.01 to 0.06% and N: 0.003 to 0.015% are suitable. The reasons for limiting the content of each component will be described below. C: 0.02 to 0.10% C requires 0.02% or more in order to utilize the γ transformation during hot rolling, but if it exceeds 0.10%, decarburization annealing in the subsequent step becomes difficult. Si: 2.5-4.5% If Si is less than 2.5%, the electric resistance is low and improvement in iron loss characteristics cannot be expected, while if it exceeds 4.5%, cold rolling becomes extremely difficult. Mn: 0.05 to 0.15%, Se and / or S: 0.01 to 0.04% Mn and Se and S are components necessary to form MnSe and MnS, and a suitable amount of Mn is 0.03 to 0.15%, Se and / or Or S is
If it is less than 0.01%, the amount of MnSe and MnS will be insufficient, and if it exceeds 0.04%, it will be difficult to disperse and precipitate it in a uniform fine size. Sb: 0.01 to 0.04% Sb contributes not only to the reinforcement of the inhibitor but also to the oxidation inhibition of the steel sheet during warm rolling. If it is less than 0.01%, the effect is poor, while if it exceeds 0.04%, the decarburizing property is remarkable. Be hindered. sol.Al: 0.01 to 0.06%, N: 0.003 to 0.015% Al and N are 0.01% and 0.00, respectively, to form AlN.
3% is necessary, while if it exceeds 0.06% and 0.015%, blistering defects called blister are likely to occur after annealing, which is not preferable.

In addition to the above-mentioned components, there is no problem in containing known elements such as Cu, Sn, Cr, Ni and Mo in one kind or in combination. The maximum allowable amount of these elements added is Cu, Sn,
Cr and Ni are 0.3% and Mo is 0.10%. Ie Cu, Sn, C
When r, Ni and the like exceed 0.3%, not only the magnetic properties are deteriorated but also the pickling property and the decarburizing property are deteriorated, which is not preferable. Also, when Mo exceeds 0.05%, decarburizing property is significantly impaired, which is not preferable.

The molten steel having the above component composition is formed into a slab in the steel making and casting process according to a conventional method, and is subjected to solution treatment of the inhibitor component at a high temperature of 1350 ° C. or higher, and then hot rolled to obtain a hot rolled sheet. .

Next, after the hot-rolled sheet is annealed, it is cold rolled once or twice or more with intervening annealing, and the rolling reduction is 40.
~ 90% is required, and if the rolling reduction is out of this range, it is good.
Secondary recrystallized structure cannot be obtained. Furthermore, the final cold rolling is 50 to 15
With multiple passes using 0 mm small diameter rolls, the total rolling reduction is 30
It is important that the first stage up to 100% be performed in the temperature range of 150 to 350 ° C, and the remaining second stage be performed in the temperature range of less than 150 ° C. Here, if the warm rolling is less than 150 ° C, {110} <001>
It is difficult to form oriented grains, while if the temperature exceeds 350 ° C, recovery occurs and the effect of warm rolling decreases. Furthermore, the iron loss can be reduced by warm rolling up to 30% of the total rolling reduction before the final cold rolling, but if the pass with the total rolling reduction of more than 30% is warm rolling, the strip shape In addition to the occurrence of operational problems such as deterioration of the quality, the balance of the texture is impaired. In addition, if the latter stage of final cold rolling is performed in a temperature range of 150 ° C or higher, it is advantageous for the growth of secondary recrystallized grains {110}.
The reduction of <001> oriented grains is remarkable, and the effect of the warm rolling in the preceding stage cannot be sufficiently exhibited. If the roll diameter is smaller than 50 mm, it becomes difficult to increase the rolling speed, while if it exceeds 150 mm, it becomes difficult to store {110} <001> oriented grains.

[0020]

Example 1 A molten steel having the composition shown in Table 3 was continuously cast into a slab, which was reheated at 1430 ° C. for 15 minutes at a high temperature and then a hot-rolled sheet with a thickness of 2.0 mm was obtained. After the sheet annealing, the first cold rolling was performed to obtain a cold-rolled sheet having a thickness of 0.62 mm, and then intermediate annealing was performed at 1100 ° C. for 60 seconds. After that, rolling was performed to a thickness of 0.45 mm in a mill having roll diameters of 80 mm and 350 mm, respectively, in a temperature range of 250 ° C., and then cold rolling was performed at room temperature to finish to a final plate thickness of 0.23 mm. Next, decarburization annealing was performed at 820 ° C. for 2 minutes in a wet hydrogen atmosphere, and then an annealing separator containing MgO as a main component was applied, followed by secondary recrystallization annealing at 850 ° C. in N ₂ atmosphere, and finish annealing. Was applied. As a result of examining the magnetic properties of the product thus obtained, as shown in Table 4, by applying the present invention, good magnetic properties were obtained.

[0021]

[0022]

Example 2 C: 0.078%, Si: 3.30%, Mn: 0.07%, Se: 0.019
%, Sb: 0.022%, Cu: 0.08%, sol.Al: 0.026%,
N: A continuous cast slab containing 0.0085% and the balance of iron and unavoidable impurities was heated at 1420 ° C for 25 minutes and then hot rolled to obtain a sheet thickness of 2.
4mm hot rolled sheet, then hot rolled sheet annealed at 1100 ℃ for 60s, then rapidly cooled to room temperature, then roll diameter
Cold rolling was performed with a 100 mm reverse mill. Cold rolling uses a induction heating device installed at the mill entrance to reduce the steel plate temperature to 30
It was rolled at 0 ° C to a thickness of 1.8 mm, then cooled to room temperature with a strip coolant, and finished to a final thickness of 0.30 mm. For comparison, warm rolling is omitted and 0.30 mm
Was also cold-rolled to the final sheet thickness. Further MgO was subjected to decarburization annealing for four minutes at 850 ° C. after applying the annealing separator consisting mainly at wet hydrogen, N _2: 25%,
Secondary recrystallization annealing and finish annealing were performed in an atmosphere of H ₂ : 75%. The magnetic properties of the product thus obtained were examined, and it was found that the conformity example: B ₈ = 1.94 T, W _17/50 = 0.98 W / kg, and the comparative example: B ₈ = 1.86 T, W _17/50 = 1.25 W / kg. there were.

Example 3 Molten steel having the composition shown in Table 5 was continuously cast into a slab, which was reheated at 1430 ° C. for 15 minutes at a high temperature and then a hot rolled sheet having a thickness of 2.7 mm and a hot rolled sheet at 1000 ° C. for 30 s. After annealing, the first cold rolling to make 1.50mm thick cold rolled sheet, then 60 seconds at 1100 ℃
Was subjected to intermediate annealing. Then the roll diameter is 80 mm and 350 mm
Each mill was rolled to a thickness of 1.10 mm in the temperature range of 300 ° C, and then cold-rolled at room temperature to a final plate thickness of 0.23 mm. Then, decarburization annealing was performed at 850 ° C. for 2 minutes in a wet hydrogen atmosphere, and then an annealing separating agent containing MgO as a main component was applied, followed by secondary re-annealing in an N ₂ : 25%, H ₂ : 75% atmosphere. Crystal annealing and finish annealing were performed. As a result of examining the magnetic properties of the product thus obtained, as shown in Table 6, by applying the present invention, good magnetic properties were obtained.

[0025]

[0026]

[0027]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide optimum conditions for warm rolling for obtaining a texture advantageous for secondary recrystallization, and thus to provide a grain-oriented silicon steel sheet having excellent magnetic properties. You can

[Brief description of drawings]

FIG. 1 is a graph showing the effect of rolling temperature on magnetic properties.

FIG. 2 is a graph showing the effect of rolling reduction on magnetic properties.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fumihiko Takeuchi             1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd.             Corporate Technology Research Division (72) Inventor Takashi Ohara             1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd.             Corporate Technology Research Division

Claims (2)

[Claims] 1. C: 0.02-0.10 wt%, Si: 2.5-4.5 wt
%, Mn: 0.05 to 0.15 wt% and Sb: 0.01 to 0.04 wt%, further Se: 0.01 to 0.04 wt% and S: 0.01 to 0.04 wt%
Steel slab having a composition containing at least one of the above is hot-rolled and at least 900 to 11 before the final cold rolling.
After continuous annealing in the temperature range of 50 ° C, rapid cooling followed by rolling in the rolling reduction range of 40 to 90%, one or more cold rolling, followed by decarburization annealing and final finishing annealing. In producing a grain-oriented silicon steel sheet by a series of steps to be performed, the final cold rolling is performed in multiple passes using a small diameter roll having a diameter of 50 to 150 mm, and the former stage up to 30% of the total rolling reduction is
A method for producing a grain-oriented silicon steel sheet having excellent magnetic properties, which is performed in a temperature range of 150 to 350 ° C, and the rest of the subsequent steps are performed in a temperature range of less than 150 ° C. 2. The steel slab further comprises sol.Al: 0.01-0.06.
The method according to claim 1, which has a composition containing wt% and N: 0.003 to 0.015 wt%.