JPH10324959A - Grain oriented silicon steel sheet with extremely low iron loss, and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the grain oriented silicon steel sheet with extremely excellent iron loss property by finely precipitating AlN and BN of the inhibitor, and containing Sb and Ni of the prescribed quantity. SOLUTION: A high silicon steel slab containing, by weight, 0.02-0.10% C, 1.5-7% Si, 0.01-0.040% Al and 0.0003-0.0050% B as inhibitor element, 0.02-1.0% Ni, and 0.005-0.15% Sb, and satisfying the inequalities of 5(X-0.05)<=Y<=10X where X is the quantity of Sb and Y is the quantity of Ni, is hot rolled, and heated and annealed. Then, the silicon steel slab is annealed by containing H2 in the atmosphere in the temperature rise process of the final finish- annealing. The grain-oriented silicon steel sheet with low iron loss can be obtained where the mean in-plane angle of deviation from (110)[001] of the crystalline orientation of the secondary crystalline grain of the steel sheet is within 4 deg., the area ratio of the crystalline grain of >=10 mm in grain size is >=75%, and the mean crystalline grain size is <=25 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a grain-oriented electrical steel sheet having extremely low iron loss, particularly among grain-oriented electrical steel sheets used for iron cores of transformers and generators.

[0002]

2. Description of the Related Art Crystal grains containing Si and comprising (1)
10) Grain-oriented electrical steel sheets strongly oriented in the [001] or (100) [001] direction are widely used as various iron core materials in the commercial frequency range because of their excellent soft magnetic properties. The characteristic required for electrical steel sheets in such applications is that, in general, the iron loss as expressed by W _17/50 (W / kg), which is the loss when magnetized to 1.7 T at a frequency of 50 Hz, is low. is important. That is, since the power loss of the generator and the transformer can be greatly reduced by using a material having a low value of _{W17 / 50} , the development of a material having a low iron loss is strongly demanded year by year.

In general, there are two methods for reducing iron loss of a material: a method of reducing eddy current loss among iron losses and a method of reducing hysteresis loss. Known methods of reducing the eddy current loss include a method of increasing the content of Si for effective high electrical resistance, a method of reducing the thickness of a steel sheet, and a method of reducing the crystal grain size. As the latter method of reducing the hysteresis loss, there is known a method of increasing the degree of integration of the crystal orientation and improving the magnetic flux density. Of these, the method of increasing the Si content, the method of reducing the thickness of the steel sheet, and the method of reducing the crystal grain size were studied. There is an unfavorable limit because the workability is deteriorated, and a method for reducing the thickness of the steel sheet is also a limit because it extremely increases the manufacturing cost.

[0004] Methods for improving the remaining magnetic flux density have been well studied so far.
No. 6-23820 discloses that Al is added to steel and hot-rolled.
There is disclosed a technique in which fine AlN is precipitated by hot-rolled sheet annealing at a high temperature of 1000 to 1200 ° C. and quenching accompanying the hot rolling, and rolling is performed at a high pressure reduction of 80 to 95%. By this method B
An extremely high magnetic flux density of 1.95 T was obtained at ₁₀ (magnetic flux density in a magnetic field of 1000 A / m). This method utilizes the fact that AlN that has been finely dispersed and precipitated has a strong effect as an inhibitor to suppress the growth of primary recrystallized grains. To obtain the crystal structure of the product. However, in this method, it is usually difficult to obtain low iron loss characteristics due to coarsening of the crystal grain size and eddy current loss, and it is difficult to completely dissolve AlN in hot-rolled sheet annealing. Therefore, it has been difficult to stably obtain a product having a high magnetic flux density.

[0005] Japanese Patent Application Laid-Open No. 2-115319 discloses a method in which Sb is further contained in steel as a segregation-type inhibitor, and special final annealing is performed. By this method, a product with high magnetic flux density was obtained,
Still, it is difficult to say that the crystal orientation integration degree is sufficient, and if the Sb content is increased to obtain a product with a higher integration degree,
Secondary recrystallization itself became insufficient, resulting in significant deterioration of iron loss characteristics.

Separately, Japanese Patent Publication No. 58-43445 discloses a method of decarburizing annealing using steel containing 0.0006 to 0.0080% of B and 0.0100% or less of N. With this method, a magnetic flux density of 1.89 T was obtained at B ₈ (magnetic flux density in a magnetic field of 800 A / m). This method can be said to be an industrially preferable method since a product having relatively stable magnetic properties can be obtained, but has not been industrialized because the magnetic flux density is low and the iron loss is not so good. Further, Japanese Patent Publication No. 54-32412 discloses a group of S or Se and As, Bi, Pb, P, Sn, C as inhibitors.
A technique using a combination of u and Ni groups is disclosed, and a relatively stable high magnetic flux density was obtained, but the iron loss characteristics were not good.

[0007] Apart from these techniques, Japanese Patent Application Laid-Open No. 2-307
No. 18 discloses a method of forming grooves on the surface of a steel sheet after cold rolling to form grooves on the surface of a product sheet, thereby reducing eddy current loss and reducing iron loss. However, this method lowers the magnetic flux density and inevitably causes the iron loss to deteriorate due to the increase in the hysteresis loss, so that a significant effect of reducing the iron loss cannot be obtained. Japanese Patent Application Laid-Open No. 5-345921 discloses that, in the production of grain-oriented electrical steel sheets containing Cu and Sn as an inhibitor in addition to AlN and MnS, a predetermined amount of Ni is added in accordance with the ratio between the Si content and the C content. Is disclosed. However, the degree of integration of the crystal orientation of the product was not sufficient, and a satisfactory low iron loss value could not be obtained.

[0008]

As described above, in order to reduce the iron loss of the grain-oriented electrical steel sheet, it is necessary to stably increase the degree of integration of the crystal orientation. It can be obtained stably. However, in the prior art, increasing the degree of integration of the crystal orientation inevitably increases the crystal grain size, which leads to deterioration and instability of the iron loss value. Since the degree of integration is reduced, the magnetic flux density is reduced. Therefore, it has not been possible to stably produce a material having a very high degree of integration of crystal orientation and low iron loss. It is an object of the present invention to drastically solve the problem of the prior art and to propose a technique for stably increasing the degree of integration of crystal orientation. That is, we, the value of B ₈ in the preparation of oriented electrical steel sheet to the AlN and BN and inhibitors to give a very high value, and essentially concern that coarsening of the crystal grain size of the product to be internalized This is to propose a technique for eliminating qualitative effects.

[0009]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have focused on the precipitation method of AlN or BN, which is an inhibitor, and have developed a very different deposition method from the conventional method. To precipitate AlN and / or BN on the primary recrystallized grains, and to obtain a strong inhibitory effect on the growth of primary recrystallized grains. It has been found that it exerts the effect of suppressing force. Ni is added as a measure for improving the texture and crystal structure to obtain a more stable low iron loss, and the Ni content is increased within a predetermined range according to the Sb content, and the C content is further increased. It has been newly found that it is effective to reduce according to the Sb content. The present invention has been completed by effectively utilizing the results of these new findings. The gist configuration of the present invention based on the above findings is as follows.

In other words, according to the present invention, the secondary recrystallized grains of the steel sheet have an average in-plane deviation angle of the crystal orientation from the (110) [001] orientation of 4 degrees or less and have a grain size of 10 mm or more. With an area ratio of 75% or more, the average crystal grain size of all crystal grains is 25 mm
The composition of the steel sheet is as follows, containing 1.5 to 7.0 wt% of Si,
Mn, Cu, Sn, Ge, Bi, V,
One or more of Nb, Cr, Te, Mo and P are used alone or in a total of two or more of 0.005 to 2.5 wt% (however, the upper limit of P is 0.30 wt%), and B is 0 to 0.0050 wt%. Including Ni
0.02 to 1.0 wt%, Sb in the range of 0.005 to 0.15 wt%, and
The Sb content X (wt%) and the Ni content Y (wt%) are contained in a range satisfying the following formula: 5 (X−0.05) ≦ Y ≦ 10X, and C is 0.003 wt% as an impurity.
Hereinafter, the total of S and Se is 0.003 wt% or less, and the content of N is 0.003 wt%.
% or less, Al and 0.002 wt% or less, Ti is reduced to 0.003 wt% or less, and the balance is composed of other unavoidable impurities and Fe. 1) invention, and in the first invention, a width of 50 to 1000 μm and a depth in a direction intersecting the rolling direction on the surface of the steel sheet.
A grain-oriented electrical steel sheet having an extremely low iron loss characterized by having grooves of 10 to 50 μm (second invention).
In the invention or the second invention, there is provided a grain-oriented electrical steel sheet (third invention) having extremely low iron loss, characterized by artificially arranging crystal grains having a grain size of 2 mm or less.
In the second invention or the third invention, the steel sheet surface is a mirror surface state or a steel sheet surface which has been subjected to crystal orientation enhancement processing, and an overcoat is applied thereon indirectly or directly. A grain-oriented electrical steel sheet with extremely low iron loss (fourth invention). In addition, the present invention relates to Si 1.
5 to 7.0 wt%, and Al and / or
Or, B is 0.010 to 0.040 wt% of Al, and B is 0.0003 to 0.0050.
In the range of wt%, S and Se are used alone or in combination with 0.005%.
-0.025 wt% and N in 0.0010-0.0100 wt%, respectively, and Mn, Cu, Sb, Sn, G
One or more of e, Bi, V, Nb, Cr, Te, Mo and P are used alone or in a total of two or more of 0.005 to 2.5 wt% (however, the upper limit of P is 0.30 wt%). A steel slab containing C, Ni and Sb, the remainder being made of other unavoidable impurities and Fe, is heated to 1300 ° C or higher, hot-rolled, and subjected to one or more cold rolling operations to achieve a final thickness. After the primary recrystallization annealing, in a series of production methods of grain-oriented electrical steel sheet subjected to final finish annealing, in the steel slab component, C
0.02 ~ 0.10wt%, Ni 0.02 ~ 1.0wt%, Sb 0.005 ~ 0.
In the range of 15 wt% and the relationship between the Sb content X (wt%), the Ni content Y (wt%) and the C content Z (wt%), the following formula: 5 (X−0.05) ≦ Y ≦ 10X −0.6 X + 0.06 ≦ Z ≦ −0.6 X + 0.11
Up to 50 ° C, the rate of temperature rise between 700 and 900 ° C for the first annealing exceeding 900 ° C after hot rolling is 2 to 30 ° C / s, and at least in the atmosphere during the temperature rise process of final finish annealing.
H ₂ is contained from 900 ° C, and N ₂
A fifth aspect of the present invention is a method for producing a grain-oriented electrical steel sheet having an extremely low iron loss, characterized in that the magnetic field subdivision forms grooves on the steel sheet surface after the final cold rolling. A sixth aspect of the present invention is a method for producing a grain-oriented electrical steel sheet having an extremely low iron loss, which is characterized by performing a surface treatment. A method for producing a grain-oriented electrical steel sheet having extremely low iron loss, wherein an orientation emphasis treatment is performed and a top coat is formed in a subsequent step (a seventh invention).

In the first invention, "B is 0 to 0.00
“50 wt%” means that B may be both added and not added.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an experiment which led to the above discovery will be described. (Experiment 1) Two slabs for directional electromagnetic steel having a thickness of 250 mm each having the components shown in Table 1 as symbols A, B, C, D, E, F and G were heated to 1390 ° C. By rolling, a hot-rolled coil having a thickness of 2.2 mm was obtained. At that time, one of the billets (A-1,
B-1, C-1, D-1, E-1, F-1, G-1)
The hot rolling is completed at a temperature of 880 ° C., and the other billet (A-
2, B-2, C-2, D-2, E-2, F-2, G-
In 2), hot rolling was completed at a temperature of 1010 ° C. After hot rolling, a large amount of coil cooling water was injected to cool at a rate of 50 ° C./s, and was wound at 550 ° C.

[0013]

[Table 1]

The heating rate of these 14 types of hot-rolled coils is 12 ° C.
/ s after the temperature was raised to 1000 ° C, subjected to hot-rolled sheet annealing held at 1000 ° C for 30 seconds, then pickled and cold-rolled to 1.8
It was rolled to a thickness of mm and subjected to an intermediate annealing at 50 ° C. in a mixed atmosphere of 50% N ₂ and 50% H ₂ at 1100 ° C. for 50 seconds. After pickling, these steel sheets have a final thickness of 0.2 at 220 ° C.
Cold rolling was performed to 22 mm. Cold-rolled, degreased steel sheet surface is 100 μm wide and 20 μm deep in the direction perpendicular to the rolling direction
Are formed at intervals of 5 mm in the rolling direction,
For a minute. Then, 8 as an annealing separator
% TiO ₂ was applied to the surface of the steel sheet and wound into a coil, followed by final finish annealing. In this final annealing, is to 800 ° C. Atsushi Nobori process from 100% N heating rate 30 ° C. for ₂ atmosphere / h, 800 ° C. to 1050 ° C. 25% of N ₂ and 75
% H ₂ mixed atmosphere, heating rate 15 ° C / h, 1050 ° C to 1150
° C. until a 100% H heating rate 20 ° C. for ₂ atmosphere / h, subsequently, subjected to retention for 5 hours at 1150 ° C. in 100% H ₂ atmosphere. After the holding treatment, the steel sheet was forcibly cooled to 800 ° C. in a 100% H ₂ atmosphere, and was cooled in a 100% N ₂ atmosphere below 800 ° C. After the final annealing, the unreacted annealing separator was removed, and a tension coat composed of 50% colloidal silica and magnesium phosphate was baked to form a product.

An Epstein size (280 L × 30 W) test piece cut out from each product along the rolling direction was subjected to strain relief annealing at 800 ° C. for 3 hours, and then the iron loss value at a magnetic flux density of 1.7 T ( W _17/50 ) and magnetic flux density (B ₈ ) were measured. Further, the steel sheet is subjected to macro-etching, and the two-dimensional distribution of crystal grains and the (110) [0]
01] and the analytical value of the component in the steel. In addition, the crystal grain size was obtained by a circle equivalent diameter, and the distribution of the crystal grains was represented by an area ratio for each crystal grain size. As for the in-plane misalignment angle, the crystal orientation in a 300 mm square was measured at a 2.5 mm pitch (excluding abnormal values at grain boundaries), and the average in-plane misalignment angle α was obtained. Table 2 shows these results together with the iron loss characteristics.

[0016]

[Table 2]

As shown in Table 2, samples A-2 and F-2
Each have an average crystal grain size of about 10 mm and a crystal grain size of 2 mm
The following area ratio is 4% or more and the crystal grain size is 10mm
Was 95% or more, the average α of the in-plane misalignment angles of the crystal grains was 4 degrees or less, and the iron loss characteristics were good, with W _17/50 being 0.66 W / kg or less. On the other hand, the samples (A-1, B-1, C-1, D-1, E-1, F-1,
G-1) are all high grain area ratio of crystal grain diameter 2 to 10 mm, an average grain plane deviation angle α is not greatly exceed 4 °, the iron loss characteristics W _17/50 Was 0.82 W / kg or more. In addition, even for a sample having a high rolling end temperature,
B-2, C-2, D-2, E-2, and G-2 have a grain size of 2 to 10 mm as compared with a sample of the same composition having a low rolling end temperature.
Although the area ratio of the crystal grains of A decreased and the area ratio of the crystal grains having a grain size of 10 mm or more increased and α also decreased, α was larger than those of Samples A-2 and F-2, and iron loss was large. The characteristics are not good when W _17/50 is 0.78 W / kg or more.

That is, Sample B-2 has a relatively small Ni content relative to the Sb content, a large average crystal grain size, and a crystal grain of 2 mm or less as compared with Samples A-2 and F-2. There were few, many crystal grains with a crystal grain size of 10 mm or more, and α was large. In the case of B-2, since the variation of crystal grains of 10 mm or more is large, it is considered that α has increased. Sample C-2 does not contain Ni as compared with Samples A-2 and F-2, has a large average crystal grain size, has few crystal grains of 2 mm or less, and has many crystal grains of 10 mm or more. , Α was large. C-2
It is considered that α increased because the in-plane deviation angle of crystal grains of 10 mm or more was large. Sample D-2 is a sample A-2
As compared with F-2, the content of C was relatively large with respect to the content of Ni, the average crystal grain size was large, the number of crystal grains having a crystal grain size of 10 mm or more was small, and α was large. In D-2, since there are many fine grains, α is considered to have increased. Sample E-2
Does not contain Ni as compared with Samples A-2 and F-2, has a large average crystal grain size, has few crystal grains of 2 mm or less, has many crystal grains of 10 mm or more, and has a large α. Was. In E-2, since the in-plane deviation angle of the crystal grains of 2 to 10 mm is large, α is considered to have increased. Sample G-2 is
Compared with Samples A-2 and F-2, the total amount of S and Se was small, the average crystal grain size was large, the number of crystal grains of 2 mm or less was small, the number of crystal grains of 10 mm or more was large, and α was large. . In G-2, since the in-plane deviation angle of the crystal grains of 2 to 10 mm is large, α is considered to have increased. That is, G-2
It is considered that excellent magnetic properties could not be obtained because there is no ability to precipitate fine precipitates such as MnS and MnSe in the steel in the hot rolling step.

From the above results, in order to obtain good magnetic properties, it is necessary to (1) use a slab containing Ni, Sb and C in appropriate amounts, and (2) increase the hot rolling end temperature. It turned out to be particularly important. When the conditions of (1) and (2) are satisfied, the crystal grains of the product have a bipolar distribution in which fine grains and coarse grains increase, and The average α of the in-plane deviation angles of the crystal grains is reduced, and the degree of integration of the crystal orientation is also improved. As a result of investigating the inhibitors before the final annealing for the samples A-2 and F-2 from which good magnetic properties were obtained, it was found that MnSe, CuSe, etc. were used as precipitation nuclei, and fine AlN was compositely precipitated around the nuclei. Was.

Thus, using MnSe, CuSe, etc. as precipitation nuclei,
The point where fine AlN precipitates around it is considered. In conventional hot rolling, it is extremely difficult to precipitate AlN uniformly and finely, and AlN cannot sufficiently function as an inhibitor. However, when the hot rolling end temperature is increased, the precipitation of AlN in the hot rolling stage can be suppressed, so that the coarsening of AlN can be prevented.
Since MnS, MnSe, CuSe, and the like are already finely precipitated in the hot rolling step, the first (in the first experiment, hot-rolled sheet annealing) heating process in the annealing process after the hot rolling,
Using MnS, MnSe, and CuSe as precipitation nuclei, extremely fine AlN can be uniformly and compositely deposited. Moreover, the composite precipitate has a strong inhibitory action because Ostwald growth is suppressed. In particular, by controlling the heating rate during the first heating step in the annealing step after hot rolling, the heating rate between 700 and 900 ° C., which is the temperature range for complex precipitation, is set to 2 to 30 ° C./s.
By doing so, the inhibitor can be more finely dispersed.

As described above, when the hot rolling end temperature is increased, a very strong inhibitor effect can be exerted by uniform fine precipitation of AlN. On the other hand, when Sb is contained, Sb segregates at the grain boundary to increase the inhibitory power and can exert a strong inhibitory action.

However, both when the hot rolling end temperature is increased and when Sb is added, there is a problem that the structure of hot rolling is deteriorated. That is, when the hot-rolling end temperature is increased, the grain structure of the hot-rolled sheet is not refined due to the promotion of grain growth after hot rolling and the reduction in the amount of γ transformation during rolling. In addition, when Sb is contained in steel at a high concentration, Sb suppresses recrystallization, resulting in deterioration of the crystal structure during hot rolling. In these cases, the hot-rolled structure is deteriorated, so that a large number of crystal grains having different orientations are included in the secondary recrystallized grains of 10 mm or more. Therefore, when Ni is contained in steel, the amount of γ transformation during hot rolling is increased, and the grain structure of the hot-rolled sheet can be reduced. Therefore, it is possible to suppress the occurrence of secondary recrystallized grains of 10 mm or more inferior in orientation. Also,
Ni has an effect of polarizing the secondary recrystallized grains into fine crystal grains and coarse crystal grains. Further, the secondary recrystallized grains having the suppressed growth and inferior orientation become crystal grains of 2 mm or less and function to stabilize iron loss. As described above, the addition of Ni increases coarse crystal grains, but also increases fine grains, so that the average crystal grain size decreases. As described above, the inclusion of Ni is advantageous for improving magnetic properties through the improvement of the structure of the hot-rolled sheet. However, when Ni is contained excessively, the crystal structure of the surface layer of the steel sheet is refined and deteriorated. It is well known that in the annealing in the cold rolling step, a decarburized layer is provided on the surface of the steel sheet to promote nucleation of secondary recrystallization. However, when Ni is excessively contained, the surface of the surface decarburized layer also partially undergoes γ transformation, resulting in a decrease in the frequency of nucleation, thereby failing to obtain a good secondary recrystallization. It is generally considered that increasing the C content in steel is also effective for increasing the γ transformation amount. However, since C is an element that is easily diffused, it is likely to be unevenly distributed in steel such as grain boundaries, and the ability of C to make the crystal structure uniform is smaller than that of Ni. When the Sb content is high, the decarburization property is deteriorated, so that the C content is not preferable. Elements such as Cu and Mn are also elements that increase γ transformation. However, elements such as Cu and Mn are S and
Combines with Se to function as an inhibitor auxiliary element. That is, when the content of elements such as Cu and Mn is changed according to the Sb content, the inhibitor function varies. Therefore,
It is not appropriate to increase the amount of elements such as Cu and Mn in order to solve the problem of Sb content.

As described above, in order to obtain secondary recrystallized grains having a good crystal orientation, the upper limit of the Ni content must be regulated in accordance with the Sb content. A product manufactured under the same manufacturing conditions as A-2 or F-2 using various slabs in which the Sb content and the Ni content are changed and other components are almost the same as the symbol A in Table 1. Is shown in FIG. In FIG. 1, the abscissa represents the amount of Sb (wt%), the ordinate represents the amount of Ni (wt%), and の も の for α ≦ 4 ° and Δ for α> 4 °. From FIG. 1, the Ni content Y (wt%), Sb
As content X (wt%), 0.02 ≦ Y, 5 (X−0.05) ≦
It can be seen that the range surrounded by Y ≦ 10X and Y ≦ 1.0 is an appropriate range.

When Sb is added to steel, decarburization is suppressed. That is, when the Sb content is high, the thickness of the decarburized layer on the steel sheet surface in the decarburization annealing step after hot rolling is reduced. When the thickness of the decarburized layer decreases, the frequency of nucleation of secondary recrystallization decreases, secondary recrystallization of grains having a good orientation cannot be expected, and the degree of integration of crystal grains of the product decreases. In order to secure a sufficient decarburization amount and obtain a secondary recrystallization having a favorable crystal orientation, it is necessary to reduce the C content according to the Sb content. C content and Sb content were changed.
FIG. 2 shows the results of measurement of α for products manufactured under the same manufacturing conditions as A-2 or F-2 of Experiment 1 using various slabs adjusted to the same components as the slab of symbol A. In FIG. 2, the horizontal axis represents the amount of Sb (wt%), and the vertical axis represents the amount of C (wt%).
の も の indicates that α ≦ 4 °, and Δ indicates that α> 4 °. From FIG. 2, the C content Z (wt%) and the Sb content X (wt
%) As 0.02 ≦ Z, −0.6 X + 0.06 ≦ Z ≦ −0.6 X
It can be seen that the range surrounded by +0.11 and Z ≦ 0.10 is the proper range.

By the way, when Ni is contained, the formation of a film is promoted in the final finish annealing, so that a uniform and good film is formed. Also, there is an effect that the purification of Al, S, Se and N from the steel is promoted. However, Ti is more likely to penetrate into steel. Therefore, it is necessary to pay particular attention to atmosphere control during high-temperature purification in final finish annealing. Experiment 2 was performed to determine appropriate conditions for atmosphere control during high-temperature purification.

(Experiment 2) Eight 250 mm thick directional magnetic steel slabs having the components indicated by the symbol A in Table 1 at 1390 ° C.
And a hot-rolled coil having a thickness of 2.2 mm was formed by hot rolling. In this hot rolling, the hot rolling was completed at a temperature of 1000 ° C., a large amount of coil cooling water was injected to cool at a rate of 50 ° C./s, and then wound at 550 ° C. These hot rolled coils are 70
Heating was performed between 0 and 900 ° C. at a heating rate of 15 ° C./s, the temperature was raised to 1000 ° C., and hot-rolled sheet annealing at 1000 ° C. for 30 seconds was performed. After hot-rolled sheet annealing, it is pickled and cold rolled to 1.8
mm, and then subjected to intermediate annealing at 50 ° C. in a mixed atmosphere of 50% N ₂ and 50% H ₂ at 1100 ° C. for 50 seconds. After pickling, these coils are heated to a final thickness of 220 ° C.
Cold rolling was performed to 0.22 mm. After cold rolling, grooves having a width of 100 μm and a depth of 20 μm were formed in the surface of the degreased steel sheet at intervals of 5 mm in a direction perpendicular to the rolling direction in the rolling direction. After the groove forming treatment, the steel sheet was subjected to decarburizing annealing at 850 ° C. for 2 minutes. Thereafter, MgO containing 10% of TiO ₂ was applied to the surface of the steel sheet as an annealing separating agent, wound up in a coil shape, and then subjected to final finishing annealing for each coil. In this final finish annealing, 80
The temperature is raised at a rate of 30 ° C / h up to 0 ° C, and at a rate of 12 ° C / h from 800 ° C to 1200 ° C.
When the temperature was lowered, it was forcibly cooled to 800 ° C, and allowed to cool below 800 ° C. 50 of temperature rise process in final annealing
Table 3 shows the atmospheric conditions from 0 ° C. to the time of holding. In addition,
From room temperature to 500 ° C., N _{2 was used} alone. When the temperature was lowered from 1200 ° C., an H ₂ atmosphere was used up to 800 ° C., and an N ₂ gas atmosphere was used after 800 ° C.

[0027]

[Table 3]

After the final finish annealing, the unreacted annealing separating agent was removed, and a tension coat consisting of 50% colloidal silica and magnesium phosphate was baked to form a product.
A specimen of Epstein size (280L x 30W) cut out from each product along the rolling direction was subjected to strain relief annealing at 800 ° C for 3 hours, and then the iron loss value (W) at a magnetic flux density of 1.7 T
_17/50 ) and a magnetic flux density (B ₈ ) at a magnetic field of 800 A / m. Further, the steel sheet is subjected to macro-etching to obtain a two-dimensional crystal grain distribution on the steel sheet surface, (110) [00
1], the average deviation angle α of the crystal orientation was determined. The analysis of components in steel was also performed. The two-dimensional crystal grain size is determined by the equivalent circle diameter, and the crystal grain distribution is expressed by the area ratio for each crystal grain size,
For the in-plane misalignment angle of the crystal, the crystal orientation was measured at a pitch of 2.5 mm in a plane of 300 mm square (excluding abnormal values at the grain boundaries). The in-plane misalignment angle was averaged to obtain α. Table 4 shows these results together with the iron loss characteristics.

[0029]

[Table 4]

As shown in Table 4, A-5, A-6,
In A-7 and A-8, W _17/50 was as good as _0.64 to 0.67 W / kg. In all of these products, the high temperature region of 900 ° C. or higher in the final finish annealing is a mixed atmosphere of N ₂ and H _2, and the area ratio of crystal grains 2 mm or less is 4% or more,
The area ratio of crystal grains of 10 mm or more is 93% or more, and α is 3
% Or less.

On the other hand, products A-3 and A-4 annealed by containing H ₂ in the atmosphere only in the high temperature region of 1000 ° C. or higher.
Was poor at W17 / _{50 of 0.83} to 0.86 W / kg. The area ratio with a crystal grain size of 2 mm or less was 2% or less, and the area ratio with a crystal grain size of 10 mm or more was 75% or less. In addition, the area ratio of the crystal grain size of 2 to 10 mm is as high as 25%, and the shift angle α of the crystal orientation is also increased to 5 ° or more. This is probably in the low temperature phase in the temperature elevation process of the finish annealing, due to a heat treatment in an atmosphere of only N _2, results of primary recrystallization grain growth of the steel sheet surface layer portion is suppressed, the secondary poor orientation primary recrystallized grains It seems to have grown. Therefore, it is necessary to include H ₂ in the atmosphere from at least 900 ° C. in the temperature rise process of the final finish annealing. Also, products A-9 and A- annealed by containing N ₂ in the atmosphere only in the low temperature region of less than 1000 ° C.
10, W _17/50 was bad, _0.78 to 0.82 W / kg. The area ratio of the crystal grain size of 2 mm or less was 3.8 mm or more, the area ratio of the crystal grain size of 10 mm or more was 95% or more, α was 3 ° or less, and the size and orientation of the secondary recrystallized grains were good. Ti content in steel is 30
Higher than ppm. Even though the size and orientation of the secondary recrystallized grains are good, the product A containing 30 ppm or more of Ti in steel
The iron loss values of 9 and A-10 are probably deteriorating.
In the Atsushi Nobori process of the finishing annealing, since heat treatment was performed in atmosphere containing N ₂ only in the low temperature region of less than 1000 ° C., it is believed to be due to Ti has penetrated in a high temperature range. N ₂ gas has a function of reducing the activity of Ti and suppressing the penetration of Ti into steel. Therefore, in the high temperature region where diffusion of Ti into steel
The inclusion of N ₂ in the atmosphere is extremely effective in suppressing the penetration of Ti into steel. Therefore, it is necessary to include N ₂ in the atmosphere at least up to 1000 ° C. in the temperature raising process of the final finish annealing.

[0032] From these facts, in the Atsushi Nobori process of final annealing, H ₂ in the atmosphere is at least 900 ° C.
It was contained, and is required for at least up to 1000 ° C. which also contain a N ₂ to obtain a good core loss property.

Experiments 1 and 2 described above are for the case where the main inhibitor is AlN. According to the investigation by the inventors, it has been confirmed that the results of Experiments 1 and 2 can be applied to the case where the main inhibitor is BN and the case where AlN and BN are mixed. This is because the precipitation behavior of BN is Al
Probably because it is almost the same as N.

Next, as another influential method for reducing iron loss, there is a magnetic domain refining process. Among them, the method of irradiating the surface of the steel sheet with a laser or a plasma jet is well known and can be applied to the present invention. Also, among the magnetic domain refinement treatments, the method of providing grooves on the steel sheet surface does not lose the iron loss reducing effect even if the product is subjected to strain relief annealing,
This is a more effective method. In the method of providing grooves, it is effective to reduce the iron loss by providing grooves having a width of 50 to 1000 μm and a depth of 10 to 50 μm in the direction intersecting the rolling direction on the surface of the steel sheet. Further, as a conventionally known iron loss reduction method, applying a mirror surface treatment and a crystal orientation enhancement treatment to the steel sheet surface to the steel sheet surface is also effective for the iron loss reduction in the present invention. The crystal orientation emphasis process is a process for exposing a crystal plane more advantageous in terms of magnetic properties. In the case where the mirror finishing treatment and the crystal orientation enhancement treatment are performed, since a forsterite-based coating does not normally exist on the steel sheet surface, an overcoat is applied via plating or the like or directly. Further, the magnetic domain refining process, the mirror finishing process, and the crystal orientation enhancing process do not prevent the combined use.

In order to more reliably obtain the grain-oriented electrical steel sheet of the present invention, a surface desiliconized layer is formed in an annealing step after hot rolling, and the steel sheet surface layer is annealed before final cold rolling. It is effective to perform an atmosphere treatment for forming a decarburized layer in the part and a rapid cooling treatment for enriching solid solution C. The former surface desiliconization layer formation treatment is to promote the growth of primary recrystallized grains on the surface layer of the steel plate in the final finish annealing,
This is effective in suppressing the occurrence of secondary recrystallization of grains having poor orientation. For this purpose, it is desirable to form a surface desiliconized layer of 0.5 μm or more. Further, in the latter annealing before the final cold rolling, the atmosphere treatment for forming a decarburized layer on the surface layer of the steel sheet promotes the nucleation of crystal grains having excellent orientation in the surface layer of the steel sheet. In particular, 1/20
It is desirable to form a decarburized layer with a thickness of about 1/5. Further, the quenching treatment at the time of annealing before the final cold rolling has the effect of increasing the concentration of solid solution C in steel, and is effective in increasing the frequency of nucleation of favorable secondary recrystallization orientation. In particular, after the quenching treatment, it is desirable to hold at a low temperature to precipitate fine carbide.

Further, increasing the number ratio by setting the area ratio of the fine particles of 2 mm or less in the product to a certain amount or less has an effect of improving the actual characteristics of the transformer. Therefore,
It is preferable to use them together in the present invention. It is particularly recommended that the number ratio be 70% or more.

It is also possible to apply the nitriding treatment in the annealing step after hot rolling using a slab having a low nitrogen concentration in steel in the present invention.

Next, with respect to the grain-oriented electrical steel sheet of the present invention and the method of manufacturing the same, the requirements for obtaining the effects of the present invention, the range thereof, and the operation will be described in detail. First, the constituent requirements of the grain-oriented electrical steel sheet of the present invention will be described. The magnetic steel sheet of the present invention is composed of many secondary recrystallized grains having a very high degree of integration. In order to reduce the hysteresis loss,
It is necessary that the area average α of the deviation angle in the in-plane direction from the (110) [001] orientation of the crystal is within 4 degrees. α
Exceeds 4 degrees, the hysteresis loss increases and iron loss deteriorates.

Further, regarding the grain size distribution of each crystal grain, it is necessary that the area ratio of crystal grains having an equivalent circle equivalent diameter of 10 mm or more is 75% or more, and the average grain size of all the crystal grains is The diameter must be 25 mm or less. As a result, the crystal grains have a crystal grain distribution in which the grains are polarized into coarse grains and fine grains, so that good magnetic characteristics can be stably obtained. Here, the area ratio of crystal grains with a diameter of 10 mm or more is
If it is less than 75%, the ratio of secondary recrystallized grains having a good orientation decreases, leading to deterioration of iron loss. On the other hand, when the average particle size exceeds 25 mm, the number of fine crystal grains of 2 mm or less decreases, the stability of secondary recrystallization is impaired, and deterioration due to instability of iron loss is also caused.

Excessive increase in the area ratio of fine particles having a particle diameter of 2 mm or less is not preferable in terms of iron loss characteristics. But 2mm
It is preferable that the ratio of the number of the following fine particles is high, because the characteristics of actual equipment such as a transformer are improved. The effect of such fine grains is due to the effect of grain boundaries. Therefore, the effect is small in ordinary fine grains generated at the grain boundaries of coarse grains, and it is particularly effective to make the fine grains exist inside the coarse grains. In order to make the fine grains exist inside the coarse grains, it is preferable to artificially arrange the fine grains. In order to artificially arrange crystal grains having a particle size of 2 mm or less, it is preferable to locally perform an energy applying process using heat, strain, or the like before, during, or during the primary recrystallization.

Next, regulations on steel components will be described. Since Si increases the electric resistance, it is a necessary component to reduce the eddy current loss of the steel sheet.
(Hereinafter, simply indicated by “%”). However, if the content exceeds 7.0%, roll rolling becomes difficult, so the content is set in the range of 1.5 to 7.0%.

[0042] In steel, as an inhibitor auxiliary component,
Mn, Cu, Sn, Ge, Bi, V, Nb, Cr, Te, Mo and P are contained alone or in combination of two or more. These components are 1
The total amount of the species alone or two or more species is in the range of 0.005 to 2.5%. If it is less than 0.005%, the assisting effect of suppressing power is small,
The effect of improving the magnetic properties is small. If it exceeds 2.5%, on the contrary, the effect of assisting the restraining force becomes excessive, and the secondary recrystallization orientation is reduced, resulting in deterioration of the magnetic properties. Note that P
Increases the hardness of the steel sheet and impairs the rollability, so the upper limit is particularly set at 0.30%.

Sb is one of the components that characterize the present invention. Sb segregates at the grain boundaries in steel and has an effect of suppressing normal grain growth. Therefore, the crystal grains of the product are coarsened and the degree of orientation integration is improved. For this effect
Sb must be contained at least 0.005%, but 0.15%
%, The decarburization becomes extremely difficult.
The range is 0.15%.

Ni is one of the components that characterize the present invention. Ni brings about the homogenization of the crystal structure during hot rolling of steel, increasing the degree of integration of the orientation of secondary recrystallized grains, and at the same time, the secondary recrystallized grains are polarized into coarse grains and fine grains. It is a component for providing crystal grain distribution and stabilizing iron loss characteristics. Ni must be at least 0.02% to achieve this effect
It is necessary that the above be contained in steel. Also, 0.02
% Or more has an effect of promoting purification and film formation during finish annealing. Since the homogenization of the crystal structure during the hot rolling is performed through the γ transformation during the hot rolling, Sb
It is necessary to increase the minimum value and the maximum value of the Ni content (Y%) according to the content (X%) of Ni. If the amount of Ni is excessive, the secondary recrystallization nucleation frequency decreases because the γ layer is partially generated at the secondary recrystallization nucleation position on the surface layer of the steel sheet, and secondary recrystallization is difficult. Has the adverse effect of becoming
Therefore, in the range of 5 (X−0.05) ≦ Y ≦ 10X, and
The upper limit is 1.0%.

It is also possible to incorporate B into the steel sheet of the present invention. B is used as an inhibitor element in place of Al, and at the same time, it is a component that easily forms fine grains. Therefore, it is possible to adjust the frequency of fine grains by appropriately adding B. For this purpose, 0.0050% of B is used. It is preferable to contain it in the following range. The lower limit as a more preferred range is 0.0003%.

Next, as impurities in steel, C, Ti, S,
Se, O, and Al all need to be reduced because they increase the hysteresis loss and deteriorate the iron loss when present in the final product steel. That is, C and Ti are each 0.003%.
Hereinafter, the total of S and Se is 0.003% or less, and O and Al are each
It must be less than 0.002%.

Next, the surface of the steel sheet is coated with a usual forsterite coating on the surface of the ground iron, and a known overcoating tension coating is applied thereon, or the surface of the ground iron is mirror-finished, and a tension coating is applied thereon. May be applied.
Further, the crystal orientation advantageous for magnetic properties is emphasized by performing a grain orientation selection process by a steel sheet surface treatment such as NaCl electrolysis so that the (110) [001] crystal orientation remains selectively. The tension film may be formed directly on the surface or indirectly by plating or the like.
These are means for better exerting the tension effect provided by the coating on the steel sheet surface.

Further, in order to improve iron loss characteristics, a groove for magnetic domain refining may be provided on the surface of the steel sheet. For this purpose, a width of 50 to 1000 μm and a depth of 10 to 50 μ
The presence of a groove of m is suitable for the purpose. In the case of a groove deviating from this condition, it is difficult to obtain a magnetic domain refining effect, and the effect of improving iron loss is small. In addition, the magnetic domain refining treatment by the groove and the mirror finishing treatment and the crystal orientation emphasizing treatment described above are not the same in the iron loss reduction mechanism, so that using both or the three in combination is a more preferable means for obtaining a low iron loss. is there. Further, as another means of magnetic domain refining, it is also possible to locally generate a minute strain inside the steel sheet by irradiation with a known laser or plasma jet.

Next, a method for manufacturing a grain-oriented electrical steel sheet according to the present invention will be described. First, the component composition range of the starting slab is as follows. C promotes the γ transformation of steel in hot rolling and improves the hot-rolled structure, so C is necessary for good secondary recrystallization. For this purpose, it is necessary to contain 0.02% or more. But,
If it exceeds 0.1%, decarburization in the middle of the manufacturing process becomes difficult, so the content is set to 0.02 to 0.10%. Si is an essential component for increasing electric resistance and reducing iron loss. For this purpose, it is necessary to contain 1.5% or more, but 7.
If it exceeds 0%, it becomes brittle and the workability deteriorates.
The range is 7.0%.

In addition to these components, the steel must contain an inhibitor component for inducing secondary recrystallization. Al and / or B and N are contained as inhibitor main components. Of these, Al must be contained at 0.010 to 0.040%. If the Al content is less than 0.010%, the amount of AlN precipitated during the heating process of hot-rolled sheet annealing is small, so that it does not function as an inhibitor. On the other hand, if it exceeds 0.040%, the inhibitor which forms a composite precipitate becomes coarse and the inhibitory power is deteriorated. Therefore, the content of Al is set to 0.010 to 0.040%.

B can be contained. In this case, since BN functions as an inhibitor that converts to AlN, the Al content can be less than 0.010%. When the content of B is less than 0.0003%, the inhibitory function is not performed because the amount of BN precipitated during the heating process of hot-rolled sheet annealing is small. If it exceeds 0.0050%, the inhibitor that forms a composite precipitate is coarsened, and the suppressing power is deteriorated. Therefore, the content of B is set to 0.0003 to 0.0050%.

N is a component constituting AlN and / or BN as the inhibitor main component. Since the necessary amount of AlN and BN can be ensured by nitriding the steel sheet even during the cold rolling process, it is sufficient for N to contain 0.0010% or more in the slab. However, if the content exceeds 0.0100%, blistering defects may occur during hot rolling, so the content is made 0.0010 to 0.0100%.

S or Se is necessary for MnS, Cu ₂ S, MnSe, Cu ₂ Se and the like to be finely precipitated in a complex with AlN or BN. For this purpose, S or Se is used alone or in a combination of 0.005%
It is necessary to contain the above. However, if it exceeds 0.025%, the precipitates become coarse. Therefore, 0.005 ~
It is contained in the range of 0.025%.

One of the features of the present invention is that Sb is further contained as an inhibitor. Sb segregates at the grain boundaries and functions as an inhibitor. To do this
Sb must be contained at 0.005% or more. But 0.15%
If it exceeds, the decarburization in the decarburization annealing will be insufficient, so the content should be up to 0.15%.

Further, Mn,
It is necessary to contain Cu, Sn, Ge, Bi, V, Nb, Cr, Te, Mo, and P singly or in a total of two or more of 0.005 to 2.5%. These components form precipitates or segregate at the grain boundary interface or the precipitate interface to perform an auxiliary function for enhancing the suppressing force. In addition, since Mn and Cu have an effect of increasing electric resistance, they have an effect of directly reducing iron loss. In order to have such an inhibitor auxiliary action,
0.005% of these elements alone or in total of two or more
It is necessary that the content be more than 2.5%. However, if the content exceeds 2.5%, the steel sheet becomes brittle and has poor decarburization.
It is contained in the range of 2.5%. Further, P increases the hardness of the steel sheet and impairs the rollability, so the upper limit is particularly set to 0.30%.

In such components and component ranges, in particular, depending on the Sb content (X%), the content of Ni (Y%) and the content of C
Adjusting the content (Z%) is one of the important requirements of the present invention. 5 (X-0.05) as Ni content
If the range of ≦ Y ≦ 10X is satisfied and falls below this range, the effect of improving the hot-rolled structure deteriorated by the inclusion of Sb is not sufficient. The frequency of nucleation of crystal grains decreases, leading to deterioration of iron loss.

Further, the content of C is -0.6 X + 0.06
≦ Z ≦ −0.6 X + 0.11 is suitable, and if it falls below this range, the effect of improving the hot-rolled structure by γ transformation during hot rolling is not sufficient. Decreases the frequency of nucleation of secondary recrystallized grains, resulting in deterioration of magnetic properties.

A steel slab formulated to this composition was
After being heated to 00 ° C. or more and subjected to hot rolling, a cold rolled sheet coil having a final thickness is obtained by cold rolling once or twice or more with intermediate annealing. This cold-rolled sheet coil is subjected to decarburizing annealing and subsequent final annealing, followed by coating and flattening annealing to obtain a product. At this time, the first
In addition, it is necessary to control the hot rolling end temperature between 900 ° C. and 1150 ° C. If the hot-rolling end temperature is lower than 900 ° C., AlN and / or BN precipitate alone during hot rolling, so that a composite fine precipitate cannot be obtained. For this reason, a strong suppressing force is lost, and iron loss deteriorates.
If the hot rolling end temperature exceeds 1150 ° C., sulfides and selenides precipitate coarsely during hot rolling. For this reason, the inhibitory power of the inhibitor decreases, and the iron loss deteriorates. Therefore, the hot rolling end temperature is controlled between 900 and 1150 ° C.

After hot rolling, it is preferable to rapidly cool the steel sheet and wind it at a low temperature. This is because AlN and / or
Or, it is for suppressing coarse precipitation of BN. The hot-rolled sheet coil thus obtained is subjected to cold rolling once or twice or more with intermediate annealing to obtain a final sheet thickness. At this time, usually, before the first cold rolling, hot-rolled sheet annealing is performed for the purpose of improving the hot-rolled structure. However, the present invention can also be applied to a manufacturing method that does not involve hot-rolled sheet annealing.

In the first annealing after 900 ° C., which exceeds 900 ° C., the heating rate between 700 ° C. and 900 ° C. is 2-30 ° C./s. The first annealing after 900 ° C. after hot rolling refers to the hot-rolled sheet annealing when hot-rolled sheet annealing exceeding 900 ° C. is performed. When not performing hot rolled sheet annealing or
In the case of performing hot-rolled sheet annealing at 900 ° C. or less and performing intermediate annealing after the first cold rolling, this refers to the intermediate annealing. In the temperature rise process of the first annealing performed after hot rolling, fine sulfides and selenides are used as precipitation nuclei to form supersaturated solid solution of Al.
It is necessary to precipitate N and / or BN in combination. The important point here is how to obtain fine composite precipitates, and for that purpose, it is necessary to strictly control the speed in the heating precipitation process of annealing. If the rate of temperature rise between 700 and 900 ° C. exceeds 30 ° C./s, the composite precipitates become coarse, leading to a decrease in the suppressing power and a deterioration in iron loss. If the rate of temperature rise is less than 2 ° C./s, the recovered structure tends to remain or the crystal grain size tends to be coarse, and the effect of improving the hot-rolled structure cannot be obtained. Therefore, the heating rate is controlled in the range of 2 to 30 ° C./s.

In the cold rolling, aging between passes, warm rolling and the like, which are known means for improving magnetic properties, can be advantageously applied. In the annealing immediately before the final cold rolling, it is preferable to perform rapid cooling when the temperature is lowered. Rapid cooling increases the amount of solid solution C in steel, and thus has the effect of increasing the frequency of nucleation of secondary recrystallization. At this time, rapid cooling and holding at a low temperature are preferable because fine carbides are precipitated in the steel and the effect of increasing the frequency of nucleation of secondary recrystallization is promoted.

The cold rolled sheet having the final thickness is subjected to decarburizing annealing. Before the decarburizing annealing, it is also possible to perform a treatment for providing a groove on the steel sheet surface. By this groove treatment, the magnetic domains of the product are subdivided, and iron loss is reduced. In addition, from the final cold rolling to before the secondary recrystallization, point-like local heat treatment or chemical treatment can be artificially performed. By these processes, fine crystal grains are generated, the magnetic domains of the product are subdivided, and iron loss is reduced.

After the final cold rolling, the steel sheet is degreased,
Perform decarburization annealing. After applying the annealing separating agent to the steel sheet after decarburizing annealing, it is wound into a coil and subjected to final finish annealing. As the annealing separator, various known annealing separators can be selected depending on whether or not a film is formed on the steel sheet surface. That is, when forming a forsterite coating on the surface of a steel sheet, an annealing separator containing MgO as a main component may be used, and when mirroring the steel sheet surface, an Al ₂ O ₃ annealing separator is often used. Used. It is also possible to apply other known annealing separators.

In the final finish annealing step, it is necessary to control the atmosphere when the temperature is raised.
It is necessary to contain H _2. The H ₂ gas has the effect of growing the crystal grains on the surface layer of the steel sheet at the time of raising the temperature of the final finish annealing, thereby suppressing the development of secondary recrystallized grains of 2 to 10 mm inferior in orientation and reducing the degree of orientation accumulation. It can be increased to reduce iron loss. For this, at least from 900 ° C
It is necessary that H ₂ be contained in the atmosphere. Furthermore, H ₂
The gas also has a function of removing impurities such as S, Se, O and N in the steel.

Further, at the time of raising the temperature of the final finish annealing,
At least up to 1000 ° C. It is necessary to contain N _2. The N ₂ gas has an effect of reducing the activity of N on the surface of the steel sheet at the time of raising the temperature of the final finish annealing to suppress the penetration of Ti into the steel, and is effective in improving the iron loss of the product. For this purpose, it is necessary to contain N ₂ in the atmosphere at least up to 1000 ° C. If an atmosphere containing no N ₂ is used from a temperature range of less than 1000 ° C. during the temperature rise, Ti penetrates into the steel and iron loss deteriorates.

After the final annealing, the unreacted annealing separating agent on the surface of the steel sheet is removed, and if necessary, further insulating coating is applied, and further flattening annealing is applied to obtain a product. It is preferable to use a tension coating as the insulating coating to improve iron loss. The steel sheet after the final annealing may be subjected to a known magnetic domain refining treatment to reduce iron loss. Examples of the magnetic domain segmentation processing include a process of irradiating a linear region with a plasma jet or a laser, and a process of providing a linear dent region by a projection roll. In addition, if a film is not formed during the final finish annealing, the steel sheet is further mirror-finished or grain orientation sorted by NaCl electrolysis, etc., and then tension coated to produce a product. It is most preferable to reduce the amount.

[0067]

【Example】

(Example 1) Steel slabs indicated by symbols A to T in Table 1 were
After heating to ° C., hot rough rolling was performed to form a 45 mm sheet bar. The hot rough rolling end temperature was 1230 ° C. This sheet bar was formed into a hot-rolled steel sheet having a thickness of 2.2 mm by hot finish rolling. The hot finish rolling end temperature was 1020 ° C. Cooling water was sprayed onto the hot-rolled steel sheet to cool it, and the hot-rolled steel sheet was coiled at 600 ° C. The hot-rolled steel sheet is heated to 1100 ° C at a rate of 15.5 ° C / s (11.5 ° C / s between 700 and 900 ° C),
The hot rolled sheet was annealed at 30 ° C. for 30 seconds. After annealing the hot rolled sheet, it was pickled and then cold rolled to a thickness of 1.5 mm. After cold rolling, the steel sheet was subjected to intermediate annealing at 1080 ° C. for 50 seconds in an H ₂ atmosphere with a dew point of 40 ° C. to reduce the C content by about 0.01%, and then sprayed with water mist at 30 ° C./s To increase the amount of solid solution C. Thereafter, the steel sheet was subjected to warm rolling at a temperature of 220 ° C. to a final thickness of 0.22 mm. After warm rolling, it is degreased, and the depth is 20 μm with a projection roll.
Grooves with a width of 150 μm were introduced at a spacing of 4 mm in the rolling direction in a direction forming 75 degrees from the rolling direction, and were subjected to decarburizing annealing at 850 ° C. for 2 minutes. The steel sheet after the decarburizing annealing was coated with an annealing separator containing MgO and 5% of TiO ₂ , and subjected to final finish annealing. In final annealing, up to 800 ° C in 100% N ₂ atmosphere at 30 ° C / h
Temperature rise rate, 800 ° C to 1050 ° C in a mixed atmosphere of 25% N ₂ and 75% H ₂ at 12.5 ° C / h, 1050 ° C to 1150 ° C
Up to 25 ° C / h in a 100% H ₂ atmosphere,
After maintaining at 1150 ° C. for 6 hours in a 100% H ₂ atmosphere, the temperature was lowered. At the time of cooling, an H ₂ atmosphere was used up to 600 ° C., and an N ₂ atmosphere was used from 600 ° C. After the final annealing, the unreacted annealing separating agent was removed, and a magnesium phosphate solution containing 50% colloidal silica was applied and baked at 800 ° C. to form a tension coating, thereby obtaining a product. Table 5 shows the properties of these products. The analytical value in steel of the product is
It was examined by wet chemical analysis.

[0068]

[Table 5]

As shown in Table 5, the grain-oriented electrical steel sheet having the component range, average grain size, crystal grain distribution, orientation accumulation degree, and impurity content of the present invention had extremely excellent iron loss characteristics.

Example 2 Seven steel slabs having the components indicated by the symbol I in Table 1 were heated to 1430 ° C., and then hot-rolled into hot-rolled coils having a thickness of 2.6 mm. At that time, the finishing temperatures of the hot-rolling finishing were 850 ° C (symbol a), 880 ° C (symbol b), 920 ° C (symbol c), 1000 ° C (symbol d), and 1090 ° C, respectively.
(Symbol e), 1140 ° C (symbol f), and 1170 ° C (symbol g). After finishing the hot rolling, a large amount of coil cooling water was sprayed onto the steel sheet surface, cooled at a rate of 50 ° C./s, and wound at 550 ° C. These seven types of hot-rolled coils have a heating rate of 12 ° C / s and a steel sheet temperature of up to 1000 ° C (a heating rate of 10.6 ° C / 700 to 900 ° C).
s) After the temperature was raised, hot-rolled sheet annealing was performed at the same temperature for 30 seconds. 1.9 mm by pickling and cold rolling after hot rolled sheet annealing
, And then subjected to intermediate annealing at 50 ° C. in a dew point of 50% N ₂ and 50% H ₂ at 1100 ° C. for 50 seconds.
After pickling, these coils were subjected to warm rolling at a steel sheet temperature of 220 ° C. to a final thickness of 0.26 mm. After warm rolling, it is degreased, and the width of the surface is 100 μm in the direction perpendicular to the rolling direction.
After forming 20μm grooves at 5mm intervals in the rolling direction, 850 ℃
For 2 minutes. After decarburization, 3% Sb ₂ O
_A mixed powder of ₃ and 32% CaO, 25% Al ₂ O ₃ and 40% MgO was applied to the steel sheet surface as an annealing separator. This annealing separator composition is for suppressing film formation. After application of the annealing separator, the film was wound into a coil and then subjected to final finish annealing. In this finish annealing, 100 up to 800 ℃
% N ₂ atmosphere at a rate of 30 ° C / h, up to 800-1050 ° C
In a mixed atmosphere of 25% N ₂ and 75% H ₂ , the temperature is raised at a rate of 15 ° C./h, and from 1050 to 1200 ° C. in a 100% H ₂ atmosphere at a rate of 20 ° C./h, Subsequently, a soaking process at 1200 ° C. for 5 hours was performed in a 100% H ₂ atmosphere, and the temperature was lowered to 800 ° C. by 100% H _2.
And cooled down to 800 ° C. or less in 100% N ₂ . After the final finish annealing, the unreacted annealing separator was removed from the steel sheet surface, and then the steel sheet surface was subjected to NaCl electrolytic treatment to select the grain orientation to emphasize the (110) plane orientation. After the electrolytic treatment, a two-layer tension coat consisting of aluminum phosphate as the lower layer of the coating and 50% of colloidal silica and magnesium phosphate as the upper layer of the coating was applied to obtain a product. An Epstein-sized (280 L × 30 W) test piece cut out from each product along the rolling direction was subjected to strain relief annealing at 800 ° C. for 3 hours, and then the iron loss value W _{17/50 at} a magnetic flux density of 1.7 T was applied. And a magnetic flux density B ₈ in a magnetic field of 800 A / m. Further, the steel sheet is macro-etched to obtain a two-dimensional crystal grain distribution and (11)
0) The average in-plane deviation angle α of the crystal orientation from [001] was determined. The analysis of components in steel was also performed. The two-dimensional crystal grain size is determined by the equivalent circle diameter, the crystal grain distribution is expressed by the area ratio of each crystal grain for each crystal grain size, and the average deviation angle α of the crystal orientation is within a plane of 300 mm square. The crystal orientation was measured at a pitch of 2.5 mm (excluding abnormal values at the grain boundaries) to determine the average value α.
Table 6 shows these results together with the iron loss characteristics. As shown in Table 6, the grain-oriented electrical steel sheet having the component range, the average grain size, the crystal grain distribution, the azimuthal degree of accumulation, and the impurity content of the present invention exhibited extremely excellent iron loss characteristics.

[0071]

[Table 6]

Example 3 C was 0.058%, Si was 3.45%,
0.07% of Mn, 0.025% of Al, 0.08% of P, 0.015% of S
%, Sb 0.058%, Ni 0.25%, B 0.0010% and N
Four steel slabs containing 0.0075%, the balance being Fe and unavoidable impurities, are heated to 1390 ° C and 35mm by hot rough rolling
It was a thick sheet bar. This sheet bar was finished to a thickness of 1.8 mm by hot rolling. At this time, the finish temperature of the hot finish rolling was 960 ° C. After the finish rolling was completed, jet water was sprayed on the steel sheet surface and quenched at a rate of 50 ° C / s to 570 ° C.
To form a hot rolled steel sheet.

Thereafter, each hot-rolled steel sheet was heated at 3 ° C./s (symbol h: the heating rate between 700 and 900 ° C. was 1.5 ° C./s) and 15 ° C./s.
(Symbol i: heating rate between 700 and 900 ° C is 12.3 ° C / s), 28
° C / s (symbol j: The heating rate between 700 and 900 ° C is 21.2 ° C /
s), 37.5 ° C / s (symbol k: The heating rate between 700 and 900 ° C is 3
The temperature was raised to 1100 ° C. at a rate of 4.6 ° C./s), and hot-rolled sheet annealing was performed for a soaking time of 30 seconds. After soaking, spray mist water
After quenching at a rate of 40 ° C / s to 350 ° C,
Hold for 2 seconds to precipitate carbide. After hot rolled sheet annealing,
Each steel sheet was warm-rolled by a Sendzimir mill at a constant temperature of 150 to 230 ° C. to a final thickness of 0.20 mm. After warm rolling, the steel sheet was subjected to a degreasing treatment and a decarburizing annealing at 850 ° C. for 2 minutes. Next, 0.08% B is contained on the steel sheet surface
An annealing separator containing 7.5% TiO ₂ and 3% SnO ₂ added to MgO was applied and wound into a coil. These coils are heated as final finish annealing to a temperature of 850 ° C in a temperature rising process at a rate of 30 ° C / h in a 100% N ₂ atmosphere at 850 ° C for 25 hours.
After holding in 0% N ₂ atmosphere, 25 ℃ from 850 ℃ to 1150 ℃
% N ₂ and 75% H ₂ in a mixed atmosphere at a heating rate of 15 ° C./h, and further kept in a 100% H ₂ atmosphere for 5 hours.
The temperature has dropped. After the final finish annealing, the unreacted annealing separating agent is removed from the steel sheet surface, a tension coating containing 50% colloidal silica is applied, and a plasma jet is linearly irradiated on the steel sheet surface at a pitch of 6 mm in the width direction of the steel sheet. The product.
Table 7 shows the magnetic properties of these products.

[0074]

[Table 7]

As shown in Table 7, extremely low iron loss values were obtained for products in which the heating rate in a predetermined temperature range of hot-rolled sheet annealing was controlled within the range of the present invention.

(Example 4) A directional electromagnetic steel slab having a thickness of 250 mm and having the components shown in the symbols P (inventive example) and E (comparative example) in Table 1 was heated to 1390 ° C and hot rolled. To give a hot-rolled coil having a thickness of 2.4 mm. In this hot rolling, the hot rolling was completed at a temperature of 980 ° C, a large amount of cooling water was sprayed on the front and back surfaces of the coil, cooled to 550 ° C at a cooling rate of 70 ° C / s, and wound into a coil. . These coils are at 400 ° C
After preheating, the mixture was rapidly cooled. Thereafter, it was subjected to hot rolled sheet annealing. In this hot-rolled sheet annealing, the heating rate between 700 and 900 ° C is 12-17 ° C / s, and the temperature is raised to 1020 ° C and
After holding for 2 seconds, gas cooling was performed. After annealing of the hot rolled sheet, pickling was performed to remove scale on the surface of the steel sheet. Then, remove the steel sheet 1.
After cold rolling to a thickness of 7 mm, intermediate annealing was performed at 1080 ° C. for 50 seconds. This intermediate annealing is performed in a dew point of 35 ° C. and in an atmosphere gas of 55% N ₂ and 45% H ₂ to form a decarburized layer on the surface layer of the steel sheet 20 μm, and cooling is performed to enrich solid solution C. Rapid cooling at 35 ° C./s was performed by spraying water mist in an N ₂ atmosphere. Then pickle, the first and second pass at 120 ° C
The final plate thickness was 0.20 mm by warm rolling at a temperature of 150 to 230 ° C from the third temperature at the following temperature. After warm rolling, degreasing is applied to the steel plate surface, width 150 μm, depth 25
A groove of μm was formed at a distance of 3 mm in the rolling direction in a direction at 85 degrees from the rolling direction, and then decarburizing annealing was performed at 850 ° C. for 2 minutes. After the decarburizing annealing, the coil of the symbol P in Table 1 (invention example) is 2
Split, one split coil is 1mm at 25mm interval on the steel plate surface
Size spot heating was applied. This spot heating
This is for generating fine grains. Thereafter, the divided coil subjected to the spot heating treatment, the remaining divided coil and a symbol E
Containing 5% TiO ₂ with the coil (comparative example)
An annealing separator made of MgO was applied to the surface of the steel sheet, wound into a coil, and then subjected to final finish annealing. The final finish annealing is performed at a rate of 30 ° C / h up to 850 ° C, and 35 ° C at 850 ° C.
After holding for a time, the temperature was raised to 1150 ° C at a rate of 12 ° C / h,
After maintaining at 1150 ° C. for 5 hours, the temperature was lowered. 850
Retention in the Atsushi Nobori process and 850 ° C. until ° C. is a gas atmosphere N ₂ plain, 850-1150 heating process up ° C. is 25% N ₂ and 75%
A gas atmosphere of H _2, the cooling process to 800 ° C. from the holding at 1150 ° C. is a gas atmosphere H ₂ plain, 400 ° C. from 800 ° C.
The temperature lowering process was performed in an N ₂ gas atmosphere.

After the final annealing, the unreacted annealing separating agent was removed, and a tension coating mainly composed of aluminum phosphate containing 65% of colloidal silica was formed to obtain a product. A test piece having a width of 150 mm and a length of 400 mm was cut out from each product, and the magnetic properties were measured. Further, the steel plate was subjected to macro-etching to obtain a two-dimensional crystal grain distribution on the steel sheet surface, an average in-plane deviation angle α of the crystal orientation of the crystal grains from (110) [001], and an analysis of components in the steel. .
Using these products, a three-phase 30 kW transformer was manufactured and its core iron loss characteristics were measured. Table 8 shows the results.

[0078]

[Table 8]

As shown in Table 8, the grain-oriented electrical steel sheet of the present invention has excellent iron loss properties, and the product subjected to the fine grain generation treatment has particularly excellent transformer properties. Has been obtained.

(Example 5) Six steel slabs each having the component indicated by the symbol I shown in Table 1 were heated to 1420 ° C, respectively, and then hot-rolled into hot-rolled steel sheets having a thickness of 2.4 mm. At that time, the finish temperature of the hot finish rolling was 980 ° C. After the completion of the hot rolling, a large amount of cooling water was sprayed on the surface of the hot-rolled steel sheet, cooled to 500 ° C. at a cooling rate of 65 ° C./s, and wound at 500 ° C. in a coil. Two of the above six hot-rolled coils (symbol I
-1 and the symbol I-2), and held at 1050 ° C. for 60 seconds,
Hot rolled sheet annealing for gas cooling was performed. 70 of these coils
The heating rate between 0 and 900 ° C was 15 ° C / s for I-1 and 35 for I-2.
° C / s. After hot-rolled sheet annealing, these steel sheets were pickled, and 1.
It was cold rolled to a thickness of 5 mm. Next, two of the remaining four hot-rolled coils (I-3 and I-4) were annealed at 650 ° C. for 10 seconds for controlling the precipitation size of carbide,
Gas cooled. After annealing, these steel plates were pickled and 1.5 mm
Cold rolled to a thickness of The remaining two hot-rolled coils (I-
5 and I-6) were pickled as they were and cold-rolled to a thickness of 1.5 mm. After cold rolling, these six steel sheets were subjected to intermediate annealing at a dew point of 35 ° C. and an atmosphere of 55% N ₂ and 45% H ₂ at 1080 ° C. for 50 seconds. This intermediate annealing is performed with 55% N ₂ and 45
The reason for performing this in the% H ₂ gas atmosphere is to form a decarburized layer on the surface layer of the steel sheet of 20 μm. In addition, in the intermediate annealing, a quenching treatment of 40 ° C./s was performed in a N ₂ atmosphere by spraying a water mist in order to increase the amount of solid solution C. Here, 700 ℃ to 900 ℃ of intermediate annealing
Up to 16 ° C./s for the steel sheets I-1, I-3 and I-5, and 38 ° C. for the steel sheets I-2, I-4 and I-6.
° C / s. After the intermediate annealing, the steel sheet is pickled and the maximum temperature
It was rolled to a final thickness of 0.22 mm by warm rolling to 250 ° C. After the final rolling, these steel sheets were degreased and subjected to decarburization annealing at 850 ° C. for 2 minutes. After decarburization annealing, 5% TiO _{2 in} MgO
Was added to a decarburized annealed plate, wound up in a coil shape, and then subjected to final finish annealing. In this final annealing, the heating rate is 30 ° C / h up to 850 ° C,
1200 ° C was 12 ° C / h. The holding was performed at 850 ° C. for 20 hours, and at 1200 ° C. for 5 hours. After maintaining at 1200 ° C. for 5 hours, the temperature was lowered. This final finish annealing atmosphere was heated to 850 ° C and held at 850 ° C for 10 minutes.
0% N ₂ atmosphere, 25% in the temperature rise stage from 850 ℃ to 1200 ℃
A mixed atmosphere of N ₂ and 75% H ₂ , holding at 1200 ° C and 100% H ₂ atmosphere in the temperature drop stage from 1200 ° C to 500 ° C, and 100% N ₂ atmosphere in the temperature drop stage from 500 ° C to 200 ° C . After the final annealing, the unreacted annealing separator was removed from the steel sheet surface. Thereafter, a coating solution mainly containing magnesium phosphate containing 65% of colloidal silica was applied and baked to form a tension coating. After the tension coating, the surface of the steel sheet was irradiated with a plasma jet in a direction of 80 ° C. from the rolling direction at an interval of 7 mm in the rolling direction to obtain a product. A test piece having a width of 150 mm and a length of 400 mm was cut out from each product, and the magnetic properties were measured. Further, the steel sheet was subjected to macro-etching, and the two-dimensional crystal grain distribution on the steel sheet surface and the average in-plane deviation angle α of the crystal grain orientation from (110) [001] were obtained. In addition, the components of the product plate were also analyzed. Table 9 shows the results. As shown in Table 9, the grain-oriented electrical steel sheet of the present invention exhibited excellent iron loss characteristics.

[0081]

[Table 9]

Example 6 A steel slab having components shown in Table 10 by symbols UA to UL was prepared.

[0083]

[Table 10]

After each of these steel slabs was heated to 1400 ° C., it was subjected to hot rough rolling to form a sheet bar having a thickness of 40 mm at 1250 ° C., and further subjected to hot finish rolling to obtain a hot-rolled steel sheet having a thickness of 2.2 mm. did. The hot rolling finish temperature was 1020 ° C. Cooling water was sprayed onto the surface of the hot-rolled steel sheet to cool it, and it was wound into a coil at 600 ° C. This hot-rolled steel sheet coil was subjected to hot-rolled sheet annealing. In this hot-rolled sheet annealing, the heating rate between 700 ° C and 900 ° C was 12 ° C / s, and the heating rate between 900 ° C and 1000 ° C was 17 ° C / s.
Then, after soaking in heat at 1000 ° C. for 40 seconds, gas cooling was performed. After annealing of the hot-rolled sheet, pickling was performed to remove scale on the surface of the steel sheet. Then, cold rolling 1.
A cold-rolled sheet having a thickness of 5 mm was used. Dew point 40 ° C, 100%
Intermediate annealing was performed at 1080 ° C. for 60 seconds in an H ₂ gas atmosphere to reduce the C content by about 0.015%. In this intermediate annealing, the solid solution C was increased by spraying a water mist at 30 ° C./s until the steel sheet temperature reached room temperature. After the intermediate annealing, the steel sheet was pickled and then subjected to warm rolling at a steel sheet temperature of 220 ° C. to a final thickness of 0.18 mm. After warm rolling,
After performing degreasing treatment, a groove having a depth of 20 μm and a width of 150 μm is formed on the surface of the steel sheet by electrolytic etching at a distance of 4 mm in the rolling direction in a direction at an angle of 80 ° with the rolling direction. Charcoal annealing was performed. To this decarburized annealed plate, to MgO
An annealing separator containing 8% of TiO ₂ was applied, wound into a coil, and then subjected to final annealing. In this final annealing, the heating rate during the heating process is 30 to 850 ° C.
° C / h, 850-1150 ° C 10.5 ° C / h, 1150-1180 ° C 15 ° C / h
And At 850 ° C., the temperature was held for 20 hours, at 1180 ° C., the temperature was held for 4 hours, and then the temperature was lowered. In addition, the atmosphere in this final finish annealing was heated up to 850 ° C and
100% N ₂ atmosphere for retention at 850 ° C, mixed atmosphere of 20% N ₂ and 80% H ₂ for temperature rise from 850 to 1150 ° C, 1150 to 1180 ° C
Up to 1,180 ° C and down to 700 ° C
The atmosphere was 100% H _2, and the temperature from 600 ° C. was 100% N ₂ . After the final finish annealing, the unreacted annealing separating agent is removed from the surface of the steel sheet, and then a coating solution mainly containing magnesium phosphate containing 70% colloidal silica is applied and then baked at 800 ° C. to form a tension coating. Product. A test piece having a width of 150 mm and a length of 400 mm was cut out from each product, and the magnetic properties were measured. Further, the steel sheet was subjected to macro-etching, and the two-dimensional crystal grain distribution on the steel sheet surface and the average in-plane deviation angle α of the crystal grain orientation from (110) [001] were obtained. Further, the components in the steel of the product plate were examined by a wet chemical analysis method. These results are tabulated.
See Figure 11. As shown in Table 11, the grain-oriented electrical steel sheet according to the present invention having the component range, crystal grain distribution, orientation integration degree, and impurity content exhibited excellent iron loss characteristics.

[0085]

[Table 11]

(Embodiment 7) The components indicated by the symbol UH in Table 10
After heating seven steel slabs each consisting of
A hot-rolled coil having a thickness of 2.6 mm was formed by rolling. At that time, heat
Rolling finish temperatures are 830 ° C (symbol l) and 880 ° C, respectively.
(Symbol m), 930 ° C (symbol n), 1000 ° C (symbol o), 10
90 ° C (symbol p), 1140 ° C (symbol q) and 1170 ° C (symbol
r) After the completion of hot rolling at each temperature, the hot rolled coil
A large amount of cooling water is sprayed at a cooling rate of 50 ° C / s,
Wound at 0 ° C. These seven types of hot rolled coils are
Annealed. In this hot-rolled sheet annealing, the heating rate was 10 ° C / s.
Heat up to 1000 ° C (heating rate between 700 and 900 ° C 8.4 ° C /
s), and kept at 1000 ° C. for 30 seconds. After hot-rolled sheet annealing,
It was pickled and cold rolled into a 1.9 mm thick cold rolled sheet. Next
Dew point 50 ℃, 50% N_TwoAnd 50% H_TwoMixed with
Intermediate annealing was performed at 1080 ° C. for 50 seconds in an atmosphere.
After pickling the coil of the intermediate annealing, it is subjected to warm rolling at 200 ° C.
The final thickness was 0.26 mm. After warm rolling, it is degreased,
A groove with a width of 100 μm and a depth of 20 μm is
Formed at an interval of 5 mm in the rolling direction in the direction of 80 degrees from
Thereafter, decarburization annealing was performed at 850 ° C. for 2 minutes. Then steel plate
3% Sb on surface_TwoO_ThreeAnd 32% CaO and 25% Al_TwoO_ThreeAnd 40%
Of mixed powder of MgO as an annealing separator
Was. The composition of this annealing separator is to suppress film formation.
It is. After applying the annealing separator, do you wind it up in a coil shape?
Were subjected to final finish annealing. In this final annealing
Is 100% N up to 800 ° C during the heating process_TwoTemperature rise rate in atmosphere
30 ° C / h, 25% N from 800 to 1050 ° C_TwoAnd 75% H_TwoMixed atmosphere
Heating rate 15 ° C / h in air, 100% H from 1050 to 1200 ° C_TwoMood
At a temperature rise rate of 20 ° C / h in an atmosphere, hold at 1200 ° C for 5 hours.
100% H_TwoPerform in an atmosphere, and cool down after soaking at 80
100% H up to 0 ° C_TwoForcibly cool in an atmosphere and reduce the temperature below 800 ° C to 10
0% N_TwoCooled in atmosphere. Unreacted after final finish annealing
After removing the annealing separator, the steel sheet surface is subjected to NaCl electrolysis to
An orientation selection process was performed to emphasize the (110) plane orientation.
Then the SiO_TwoAnd Al _TwoO_ThreeGlass + ceramics tension core
The product was coated. Along the rolling direction from each product
Cut out Epstein-sized test pieces at 800 ° C for 3
After 1.7 hours of strain relief annealing, a magnetic flux density of 1.7 T
Iron loss value W_17/50And magnetic flux density B at 800 A / m magnetic field₈To
It was measured. Also, macro etching of the steel sheet
Two-dimensional grain distribution on the surface and (110) [00
1], the average in-plane deviation angle α of the crystal orientation was determined. Change
Next, the components in the steel were analyzed. This two-dimensional grain size is
Determined by equivalent circle diameter, and the crystal grain distribution is based on the crystal grain size of each crystal grain
The average in-plane deviation angle of the crystal orientation is 300
The crystal orientation is measured at 2.5 mm pitch in a plane of
Excludes outliers in some parts. ), Find the average value α of the in-plane deviation angle
Was. Table 12 shows these results together with the magnetic properties. Table 12
As shown in the table, the component range of the present invention, the average crystal grain size,
Directional electromagnetic of grain distribution, degree of orientation accumulation and impurity content
The steel sheet exhibited extremely excellent iron loss characteristics.

[0087]

[Table 12]

(Example 8) 0.068% of C, 3.25% of Si,
Mn 0.06%, Al 0.005%, P 0.03%, S 0.015%
%, Sb 0.046%, Ni 0.28%, B 0.0032% and N
Four steel slabs containing 0.0077% and the balance being iron and unavoidable impurities were heated to 1380% and hot rough rolling was performed to form a 35 mm thick sheet bar. This sheet bar was subjected to finish rolling to a sheet thickness of 1.8 mm. At this time, the finish rolling end temperature was set to 970 ° C., and after rolling, jet water was sprayed on the steel sheet surface, rapidly cooled at a rate of 65 ° C./s, coiled at 580 ° C. to obtain a hot-rolled steel sheet. After that, each hot rolled steel sheet is 3
° C / s (symbol: s; heating rate between 700 and 900 ° C is 1.5 ° C / s
s), 15 ° C / s (symbol t; the heating rate between 700 and 900 ° C is 12.
3 ° C / s), 28 ° C / s (symbol u; heating rate between 700 and 900 ° C is 21.2 ° C / s) and 37.5 ° C / s (symbol v; heating rate between 700 and 900 ° C is 34.6 ° C) / s) at a heating rate of 1100 ° C,
After performing hot-rolled sheet annealing for a soaking time of 30 seconds, mist water was sprayed and rapidly cooled to 350 ° C. at 45 ° C./s, followed by holding at 350 ° C. for 30 seconds to precipitate carbide. Thereafter, each of the steel sheets was subjected to warm rolling at a constant temperature of 150 to 230 ° C. by a Sendzimir rolling mill to a final thickness of 0.20 mm. After this, the steel sheet is degreased and decarburized at 850 ° C for 2 minutes.
Then 7.5% TiO ₂ and 3% MgO containing 0.08% B
Of SnO ₂ was added and applied as an annealing separator, and wound up in a coil shape. These coils up to 850 ° C. heating process was raised at a heating rate of 30 ° C. / h in 100% N ₂ atmosphere as final annealing was held at 25 hours 100% N ₂ atmosphere at 850 ° C. Thereafter, the temperature was raised from 850 ° C. to 1150 ° C. at a rate of 15 ° C./h in a mixed atmosphere of 25% N ₂ and 75% H ₂ ,
After holding in a 100% H ₂ atmosphere for an hour, the temperature was lowered. Then, after removing the unreacted annealing separating agent on the surface of these coils, forming a tension coating containing 50% colloidal silica, and irradiating a plasma jet linearly in the plate width direction at a pitch of 6 mm. And Table 13 shows the magnetic properties of these products. As shown in Table 13, for the products in which the heating rate in the predetermined temperature range of the hot-rolled sheet annealing was controlled within the range of the present invention, an extremely low iron loss value was obtained.

[0089]

[Table 13]

Although the present invention has been described based on the embodiments, the present invention is not limited to the scope of the embodiments.

[0091]

As described in detail above, according to the grain-oriented electrical steel sheet of the present invention and the method for producing the same, a method for producing a high magnetic flux density grain-oriented electrical steel sheet having extremely excellent iron loss characteristics becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the appropriate range of the content of Ni contained in a steel slab of the present invention and the content of Sb.

FIG. 2 is a view showing the relationship between the appropriate range of the C content contained in the steel slab of the present invention and the Sb content.

Claims (7)

[Claims] The secondary recrystallized grains of a steel sheet have a crystal orientation of (1).
10) the average in-plane deviation angle from the [001] orientation is within 4 degrees, the area ratio of crystal grains having a grain size of 10 mm or more is 75% or more, and the average crystal grain size of all the crystal grains is 25 mm or less; The composition of the steel sheet contains 1.5-7.0 wt% of Si, and Mn, Cu, Sn, Ge, Bi, V,
One or more of Nb, Cr, Te, Mo and P are used alone or in a total of two or more of 0.005 to 2.5 wt% (however, the upper limit of P is 0.30 wt%), and B is 0 to 0.0050 wt%. In addition, Ni is in the range of 0.02 to 1.0 wt%, Sb is in the range of 0.005 to 0.15 wt%, and the relationship between the Sb content X (wt%) and the Ni content Y (wt%) is expressed by the following formula 5 (X− 0.05) ≦ Y ≦ 10X, and C is contained as an impurity in an amount of 0.003 wt%.
Hereinafter, the total of S and Se is 0.003 wt% or less, and the content of N is 0.003 wt%.
A grain-oriented electrical steel sheet having extremely low iron loss, characterized in that the content of Al is reduced to 0.002 wt% or less, the content of Ti is reduced to 0.003 wt% or less, and the balance consists of other unavoidable impurities and Fe. 2. A steel sheet having a width in a direction intersecting a rolling direction on a surface of a steel sheet.
2. The grain-oriented electrical steel sheet according to claim 1, wherein the grain has a groove of 50 to 1000 [mu] m and a depth of 10 to 50 [mu] m. 3. The grain-oriented electrical steel sheet according to claim 1, wherein crystal grains having a grain size of 2 mm or less are artificially arranged. 4. The steel sheet surface according to claim 1, wherein the steel sheet surface is a mirror-finished state or a steel sheet surface which has been subjected to crystal orientation enhancement processing, and an overcoat is applied thereon indirectly or directly. 4. The grain-oriented electrical steel sheet according to any one of 2 or 3, having extremely low iron loss. 5. An alloy containing 1.5 to 7.0 wt% of Si and containing 0.010% of Al and / or B as an inhibitor element.
-0.040wt%, B is 0.0003-0.0050wt%, S
And Se alone or in a combination of 0.005 to 0.025 wt%, N
Mn, Cu, Sb, Sn, Ge, B
One or two or more of i, V, Nb, Cr, Te, Mo and P are used alone or in a total of 0.005 to 2.5 wt% of the total of two or more (however,
The upper limit of P is 0.30 wt%). Further, the steel slab containing C, Ni, and Sb and the remainder is made of other unavoidable impurities and Fe is heated to 1300 ° C or more, hot-rolled, and Alternatively, in a method for producing a series of grain-oriented electrical steel sheets in which a final thickness is obtained by performing cold rolling a plurality of times, and then a primary recrystallization annealing is performed, and a final finishing annealing is performed, the steel slab component may be configured such that C is 0.02 to 0.10 wt%. %, Ni
0.02 to 1.0 wt%, Sb in the range of 0.005 to 0.15 wt%, and
The relationship between the Sb content X (wt%), the Ni content Y (wt%), and the C content Z (wt%) is as follows: 5 (X−0.05) ≦ Y ≦ 10X−0.6 X + 0. 06 ≦ Z ≦ −0.6 X + 0.11 and hot rolling end temperature between 900 ° C and 1150 ° C, 700-900 ° C for the first annealing exceeding 900 ° C after hot rolling
The rate of temperature rise between 2 and 30 ° C./s, H ₂ is contained in the atmosphere from at least 900 ° C. in the temperature rise process of final finish annealing, and at least up to 1000 ° C.
Very manufacturing method of low-oriented electrical steel sheet iron loss, characterized in that the inclusion of N _2. 6. The method for producing a grain-oriented electrical steel sheet with extremely low iron loss according to claim 5, wherein a magnetic domain refining treatment for forming a groove on the steel sheet surface is performed after the final cold rolling. 7. An extremely low iron loss according to claim 5, wherein a mirror finish treatment or a crystal orientation emphasis treatment is performed after the final annealing, and a top coat is formed in a subsequent step. Manufacturing method of grain-oriented electrical steel sheet.