JP2001295062A - Grain oriented silicon steel sheet having excellent magnetic characteristic and film characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grain oriented silicon steel sheet having a foresteritic film which acts more advantageously on magnetic characteristics than the conventional forsterite film and has an excellent film adhesion property as well. SOLUTION: The chief components of the foresteritic film are formed of Mg2SiO4, FeAl2O4 and TiN.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain-oriented silicon steel sheet excellent in magnetic properties and coating properties suitable for use as an iron core of a transformer or other electric equipment.

[0002]

2. Description of the Related Art Grain-oriented silicon steel sheets are mainly used as iron core materials for transformers and rotating equipment, and are required to have high magnetic flux density and small iron loss and magnetostriction as magnetic characteristics. In particular, in recent years, from the viewpoint of energy saving and resource saving, there is an increasing need for a grain-oriented silicon steel sheet having excellent magnetic properties.

[0003] In order to obtain a grain-oriented silicon steel sheet having excellent magnetic properties, it is important to obtain a secondary recrystallized structure highly integrated in the {110} <001> orientation, the so-called Goss orientation. Such a grain-oriented silicon steel sheet is prepared by heating a hot rolled silicon steel slab containing an inhibitor required for secondary recrystallization, for example, a silicon steel slab containing MnS, MnSe, AlN, BN, etc. Rolled sheet annealing, and once or intermediate annealing 2
The steel sheet is manufactured by performing a final strip thickness by cold rolling more than once, performing decarburization annealing, applying an annealing separator mainly containing MgO to the steel sheet, and then performing final finish annealing.

[0004] The surface of this grain-oriented silicon steel sheet is forsterite (Mg ₂ SiO ₄ ) except for special cases.
In general, an insulating coating mainly composed of a forsterite coating (hereinafter simply referred to as a forsterite insulating coating or a forsterite coating) is formed. The coating effectively improves iron loss and magnetostriction by applying not only electrical insulation on the surface but also tensile stress to the steel sheet due to its low thermal expansion property. Therefore, if the coefficient of thermal expansion of the forsterite film can be reduced by any method, further improvement in iron loss can be expected.

From the above viewpoints, an example in which a compound having a lower coefficient of thermal expansion than forsterite is formed in a forsterite film to improve the magnetic characteristics and film characteristics is disclosed in Japanese Patent No. 270000. MgAl ₂ O
₄ and Patent No. 2984195 are known. Here, the existence of MgAl ₂ O ₄ was reported by Fujii et al. In `` Glass Film Structure of Grain-Oriented Si
licon Steel Using Aluminum Nitride as an Inhibitor
(Journal of Materials Engineering and Performanc
e, Vo1.3 (2) April 1994, p. 214), it can be seen that when CuKα is used as the X-ray target, it can be confirmed from a peak near 2θ = 37 °. This is MgAl ₂ O ₄ (311)
It can be seen that the peak is clearly separated from the (211) peak of Mg ₂ SiO ₄ (see FIG. 1). Patent No.
As disclosed in Japanese Patent No. 2984195, the presence of TiN is determined by using 2θ = 42.6 when CuKα is used as an X-ray target.
It can be confirmed from a peak near °, which is a TiN (200) peak.

Although the magnetic properties and the coating properties of the grain-oriented silicon steel sheet have been improved by these, the trend of the energy saving era calls for further improvement of the properties. Therefore, the inventors have found that TiN and MgAl are contained in the forsterite film.
_It was considered that the coexistence of ₂ O ₄ could further improve the magnetic properties and the film properties, and various investigations were carried out. However, unsatisfactory results could not always be obtained. Even when TiN and MgAl ₂ O ₄ coexist in the forsterite film, the film formation behavior is still limited to MnS, MnSe, and AlN in steel.
In addition, it also affects the behavior of inhibitors, such as secondary recrystallization itself, which is an essential process for obtaining excellent magnetic properties. Therefore, it is considered that even if the intended coating composition was obtained, it did not necessarily lead to improvement in magnetic properties.

[0007]

SUMMARY OF THE INVENTION The present invention advantageously solves the above-mentioned problems. Forsterite which has an advantageous effect on magnetic properties as compared with a conventional forsterite coating and has excellent coating adhesion. The purpose is to propose a grain-oriented silicon steel sheet having a porous coating.

[0008]

The details of the invention will be described below. As described above, even when TiN and MgAl ₂ O ₄ coexist in the forsterite film, good magnetic properties could not always be obtained. Therefore, the present inventors have developed good secondary recrystallization and have developed TiN and MgAl.
To coexist ₂ O _4, a result of reviewing the technical contents disclosed in Japanese Patent No. 2710000 Patent Publication and Patent No. 2984195 publication, forsterite film is an annealing separator and one of the raw materials, also decarburization annealing In contrast to the occasional generation of sub-scale as the other raw material, the above-mentioned technology led to the idea that the study on the conditions for decarburizing annealing was insufficient.

Therefore, based on the technology disclosed in Japanese Patent No. 2984195 for forming TiN in the forsterite film, the decarburizing annealing conditions were examined by focusing on the temperature rise rate and the atmospheric oxidation degree during decarburizing annealing. Was. The reason for paying attention to the heating rate during decarburization annealing is that many studies have been made on the heating rate in the past (for example, JP-A-60-121222, JP-A-4-160114, and JP-A-4-160114). No. 6,128,646) are all made from the viewpoint of improving the magnetic properties, and do not focus on the film properties.

That is, the present inventors have conducted intensive studies on the conditions for decarburization annealing. As a result, the average heating rate from normal temperature to 750 ° C. is 12 to 35 ° C. at a soaking temperature of 800 ° C. or more and 900 ° C. or less.
/ s, and from 750 ° C to the soaking temperature, the average heating rate: 1 to 10 ° C / s, and the degree of atmospheric oxidation (P (H ₂ O) / P ( (H ₂ ); the ratio of the partial pressure of steam to the partial pressure of hydrogen in the atmosphere) was 0.35 to 0.50, and it was found that when decarburizing annealing was performed, extremely excellent magnetic properties and coating properties were obtained.

However, when those forsterite films were examined, TiN was generated in the films.
MgAl ₂ O ₄ was not formed. An example is shown in FIG. 2, but it can be seen that the (311) peak of MgAl ₂ O ₄ is not observed near 2θ = 37 °. However, at around 2θ = 19 ° or 31 °, an unknown peak which cannot be identified by Mg ₂ SiO ₄ and TiN (☆
Mark), it was considered that they were caused by the Al compound, and an investigation revealed that it was a FeAl ₂ O ₄ peak. According to the JCPDS card, FeAl
The (311) peak of ₂ O ₄ (JCPDS No.34-192) is Mg ₂ SiO ₄ (JCP
It can be seen that the peak almost overlaps with the (211) peak in DS No. 34-189). On the other hand, as described above, MgAl ₂ O ₄ (JCPDS No.
21-1152), the (311) peak of Mg ₂ SiO ₄
(211) It can be clearly distinguished from the peak. Therefore, FeAl ₂ O ₄
Is the MgAl due to its (311) peak and the above-mentioned ☆ mark.
It can be separated from ₂ O ₄ .

As a result, in the case where Al is contained in steel and AlN is used as an inhibitor, Patent No. 27100 is used as Al oxide.
Instead MgAl ₂ O ₄ is disclosed in 00 JP, FeAl ₂ O ₄
It has been newly found that the formation of and the coexistence of TiN in the forsterite coating provide extremely excellent magnetic properties and coating properties. The present invention is based on the above findings.

That is, the present invention is directed to a grain-oriented silicon steel sheet having a forsterite coating on its surface, wherein the forsterite coating is made of Mg ₂ SiO ₄ , FeAl ₂ O ₄ and TiN.
This is a grain-oriented silicon steel sheet having excellent magnetic properties and coating properties, characterized by being mainly composed of.

Further, the present invention provides a
A grain-oriented silicon steel sheet having a
Stellite coating is Mg_TwoSiO_Four, FeAl_TwoO_FourAnd TiN
And Mg by thin film X-ray diffraction on the coating surface_TwoSiO_Four(13
1) Set the peak intensity to I₀ , FeAl _TwoO_FourThe intensity of the (111) peak is I
₁ , TiN (200) peak intensity I_Two And when
Is given by the following formula (1), (2) 3/100 ≦ I₁ / I₀ ≤40 / 100 --- (1) 3/100 ≤I_Two / I₀ ≤40 / 100 --- (2) where I₁ / I₀ + I_Two / I₀ Magnetic characteristics and film characteristics characterized by satisfying the relationship of ≤50 / 100
This is a highly oriented silicon steel sheet.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, experimental results which led to the present invention will be described. Hereinafter, “%” used to indicate the content of each element indicates a mass percentage (mass%) unless otherwise specified. Experiment 1 C: 0.072%, Si: 3.42%, Mn: 0.069%, Se: 0.019
%, Al: 0.025%, N: 0.0084%, Cu: 0.10%, Sb: 0.
At a temperature of 1430 ° C.
After heating for one minute, a hot-rolled sheet having a thickness of 2.4 mm was formed by hot rolling.
Then, after the hot-rolled sheet was annealed at 1000 ° C for 1 minute, the first sheet was cold-rolled to an intermediate thickness of 1.7 mm, the intermediate sheet was annealed at 1050 ° C for 1 minute, and the second sheet was cold-rolled. Thickness: 0.23
mm. Thereafter, in after the surface was degreased resulting cold-rolled sheet was cleaned, H ₂ -H ₂ O -N ₂ atmosphere 850
At a temperature of ° C., the basis weight of oxygen per side is 0.4 to 0.8 g / m ²
The steel was subjected to decarburization annealing. At that time, T ₁
° C (T ₁ = 600, 650, 700, 750, 800, 850) and the rate of temperature increase from T ₁ ° C to 850 ° C are independent of each other. Was changed in the range of 0.5 to 20 ° C./s. The degree of oxidation of the atmosphere represented by P (H ₂ O) / P (H ₂ ) during soaking was set to 0.2 to 0.7.

Next, an annealing separator containing MgO as a main component and 10 parts by weight of TiO ₂ with respect to 100 parts by weight of magnesia was formed into a slurry, applied to each decarburized annealed plate coil, and dried. Magnesia had a hydration of 2%, a citric acid activity (CAA40) at 30 ° C of 75 seconds, and a BET
(Specific surface area) of 25 m ² / g was used. After that, in a nitrogen atmosphere, after a holding treatment at 850 ° C for 20 hours, a secondary reheating is performed at a rate of 10 ° C / h to 1150 ° C in an atmosphere of nitrogen: 25 vol% and hydrogen: 75 vol%. The crystal was annealed and a final annealing was performed in a hydrogen atmosphere at 1200 ° C. for 5 hours.
At that time, the sample was pressed at a temperature of 850 to 1150 ° C with a load of 98 MPa, and the unit weight (kg) and
The gas flow rate per (h) was 1 × 10 ^-2 m ³ / (kg · h).
The pressurization is based on the winding tension in the actual process and the pressure between the steel plates due to the thermal expansion of the coil during temperature rise.

The appearance, bending adhesion and magnetic properties of the forsterite film of the sample thus obtained were evaluated.
T ₁ = 85, which corresponds to heating at a constant rate from room temperature
At 0 ° C., under these conditions, it was not possible to obtain both excellent magnetic properties and coating properties in any case. Also,
Even when the rate of temperature rise from room temperature to T ₁ ° C was slower than the rate of temperature rise from T ₁ ° C to 850 ° C, excellent characteristics could not be obtained. Conversely, the rate of temperature rise from room temperature to T ₁ ° C is
_{When the} heating rate was higher than ₁ ° C. to 850 ° C., it was easy to obtain excellent coating properties. However, when T ₁ <700 ° C., good magnetic properties could not be obtained. In this case, it is considered that the influence on the formed primary recrystallization texture was great.

On the other hand, very good magnetic properties and coating properties were obtained over a relatively wide range when T ₁ = 750 ° C. In particular, P (H ₂ O) / P (H ₂ )
When the degree of oxidation of the atmosphere represented by was 0.35 to 0.50, both excellent magnetic properties and coating properties could be obtained. FIG. 3 shows that the degree of oxidation of the atmosphere at T ₁ = 750 ° C.
The evaluation results of the magnetic characteristics and the film characteristics at 0.35 to 0.50 are shown. The bending adhesion of the coating was evaluated by wrapping a test piece around a round bar having a diameter of 5 mm and having various diameters, and evaluating the minimum diameter at which the coating did not peel off.

As is apparent from FIG.
Up to 12-35 ° C / s and 750-850
It can be seen that by setting the rate of temperature rise between 1 ° C and 1 ° C / s to 10 ° C / s, extremely excellent magnetic properties and film properties can be obtained together (the degree of oxidation of the atmosphere during soaking is 0.35 to 0.50). Further, when these forsterite coatings were examined, TiN and FeAl ₂ O ₄ were formed in the coatings in addition to forsterite, and MgAl ₂ O ₄ was not formed.

At the time of decarburizing annealing, the temperature is raised from room temperature to 750 ° C. at a rate of 12 to 35 ° C./s and the rate of temperature rise from 750 ° C. to a soaking temperature is 1 to 10 ° C./s. The inventors consider the reason why the characteristics and the film characteristics are improved as follows. That is, the inventors conducted a preliminary experiment to examine the weight change before and after pickling under the pickling conditions of 5% HCl at 60 ° C. for 60 seconds, that is, the pickling weight loss of the decarburized and baked pure plate. And there is a correlation between magnetic properties and film properties,
It was found that the lower the pickling loss value, the better the magnetic and coating properties tended to be. It is considered that the pickling weight loss value reflects the properties of the outermost surface of the sub-scale, and therefore affects the reaction in the initial stage of film formation in some way.

Therefore, the relationship between the heating rate during decarburization annealing and the pickling weight loss value was examined. When the heating rate was controlled within the above range, the pickling weight loss value was higher than in the other cases. Was low, and it was found that the pickling weight loss value could be suppressed to a low value of 0.3 g / m ² or less. The reason that the lower the pickling weight loss value, the better the magnetic and coating properties are, is not clearly understood, but it is presumed to indicate the reactivity with the atmosphere on the steel sheet surface, that is, the activity. Therefore, it is considered that the lower the pickling weight loss value and the lower the activity, the less the influence of the atmosphere in the finish annealing, that is, the water vapor released from the water of hydration of magnesia. It is considered that the reason why the pickling weight loss value is reduced by defining the heating rate as described above is that a dense subscale is formed in the initial oxidation by lowering the heating rate in the initial oxidation.

In addition, P (H ₂ O) / P (H ₂ ) during decarburization annealing and ripening
The inventors believe that the reason why the magnetic / coating property is improved by setting the degree of oxidation of the atmosphere represented by the above to 0.35 to 0.50 is as follows. In other words, the structure of the SiO ₂ layer in the subscale changes due to the difference in the degree of oxidation of the atmosphere during decarburization annealing and soaking, but the difference in the structure changes the film formation process during finish annealing, resulting in extremely excellent magnetic properties. It is thought to cause an inhibitor degradation process that leads to

That is, the change in the structure of the SiO ₂ layer in the subscale due to the difference in the degree of oxidation in the decarburizing annealing / soaking atmosphere is evaluated by the electrochemical subscale evaluation disclosed in JP-A-8-218124. Can be grasped by law. Voltage of this method - the time the voltage change amount V ₃₄ values obtained from the curve is reflecting the properties of the SiO ₂ layer in the subscale, V ₃₄ by the atmosphere oxidizing degree during soaking in the range of 0.35 to 0.50 Values ranged from -0.05 to +0.05 (V). That is, the temperature rises at an average rate of 12 to 35 ° C / s from normal temperature to 50 ° C, and the average rate of temperature rise is 1 to 10 from 750 ° C to 850 ° C.
Temperature rise at ℃ / s, and the degree of atmospheric oxidation at the time of soaking (P (H ₂ O) / P
(H ₂ ); the ratio of the partial pressure of water vapor to the partial pressure of hydrogen in the atmosphere).
By performing the decarburization annealing under conditions of 35 to 0.50, a pickling weight loss values of the subscales 0.3 g / m ² or less, the V ₃₄ value -0.05
By controlling to 0.05 (V) and regulating the surface reactivity and internal structure to a certain range, it is possible to obtain a grain-oriented silicon steel sheet having extremely excellent magnetic properties and coating properties. Here, the _V34 value is a value relating to the voltage in the third region of the voltage change curve, and is expressed by the following formula: _V34 value = (voltage value at end of third region) − (voltage value at beginning of third region) It is defined. However, the voltage value at the beginning of the third region is a voltage value when the amount of voltage drop for one second is less than 0.01 V and it starts to continue continuously for two seconds or more.
The voltage value at the end of the area means that the voltage drop per second is 0.01 V
This is the voltage value that is as described above and that continues for more than 4 seconds.

Next, based on the above findings, the amount of TiN and the amount of FeAl ₂ O _{4 in the}
An experiment was conducted to examine the relationship with the coating properties. Experiment 2 C: 0.069%, Si: 3.44%, Mn: 0.071%, Se: 0.018
%, Al: 0.026%, N: 0.0087%, Cu: 0.10%, Ni: 0.
A steel slab having a composition containing 20% and Sb: 0.043%
After heating at a temperature of 20 ° C. for 20 minutes, a hot-rolled sheet having a thickness of 2.6 mm was formed by hot rolling. Then, after hot-rolled sheet annealing at 1000 ° C for 1 minute,
The first cold rolling makes the sheet thickness: 1.8 mm intermediate thickness, 1100
After the intermediate annealing at 1 ° C. for 1 minute, a final thickness of 0.23 mm was obtained by the second cold rolling. Thereafter, the obtained cold-rolled sheet was degreased to clean the surface, and then, in an atmosphere of H ₂ —H ₂ O—N ₂ at a temperature of 820 ° C., an oxygen basis weight per one side was reduced.
Decarburization annealing was performed to 0.4 to 0.8 g / m ² . At that time, from room temperature to T ₁ ° C (T ₁ = 600, 650, 700, 750, 8
00, 850) and the rate of temperature rise from T ₁ ° C to 850 ° C, respectively, the former being 5 to 50 ° C / s and the latter being
It was changed in the range of 0.5 to 40 ° C / s. In addition, P (H
₂ O) / P oxidation degree of the atmosphere represented by (H ₂₎ was 0.30 to 0.55.

Next, an annealing separator containing MgO as a main component and 8 parts by weight of TiO ₂ with respect to 100 parts by weight of magnesia was made into a slurry, applied to each decarburized annealed plate coil, and dried. In addition, magnesia has a hydrated amount.
1.5%, citric acid activity at 30 ° C CAA40) 65 seconds, BET
(Specific surface area) of 15 m ² / g was used. After that, in a nitrogen atmosphere, after a holding treatment at 850 ° C. for 20 hours, a secondary reheating is performed at a rate of 10 ° C./h to 1150 ° C. in an atmosphere of nitrogen: 25 vol% and hydrogen: 75 vol%. The crystal was annealed and a final annealing was performed in a hydrogen atmosphere at 1200 ° C. for 5 hours.
At that time, samples were taken at 0,49,98,
Pressurized under 5 conditions of 147, 196 MPa and unit weight of steel plate
(kg) and gas flow rate per unit time (h) are 1 × 10 ^-5 ,
1 × 10 ^-4 , 1 × 10 ^-3 , 1 × 10 ^-2 , 1 × 10 ^-1 , 1 m ³ / (kg
・ Changed in 6 steps of h). The pressurization is based on the winding tension in the actual process and the pressure between the steel plates due to the thermal expansion of the coil during temperature rise. It was done.

The forsterite of the sample thus obtained
The relationship between porous coatings and magnetic and coating properties, especially coatings
Mg by thin film X-ray diffraction on the surface_TwoSiO_Four(131) Peak intensity I
₀ , FeAl_TwoO_Four(111) Peak intensity I₁ , TiN (200) peak
Strength I_Two Of the relationship between magnetic properties and magnetic and coating properties
Was. At this time, the pickling weight loss value of the decarburized annealed plate subscale
0.3 g / m^Two Below, V₃₄Value in the range of -0.05 to +0.05 (V)
Under satisfactory conditions, MgAl in the forsterite coating _TwoO
_Four Not FeAl_TwoO_FourHad been generated.

FIG. 4 shows the relationship between I ₁ / I ₀ and the magnetic characteristics when I ₂ / I ₀ is not less than 5/100 and not more than 10/100.
When I ₁ / I ₀ is 3/100 or more, W _17/50 ≦ 0.82 W /
It can be seen that an extremely good iron loss of kg is obtained. Also,
When FeAl ₂ O ₄ is generated from the magnetic flux density (B ₈₎ is improved, possibly iron loss reducing effect by FeAl ₂ O ₄ produced,
It is considered that the effect of improving the magnetic flux density (B ₈ ) is large in addition to the effect of improving the film tension. The inhibitor decomposition process is affected by the difference in the film formation process, but under conditions where TiN is formed, it is more likely that MgAl ₂ O ₄ is formed during the film formation process and that FeAl ₂ O ₄ is formed. Is considered to be an advantageous inhibitor decomposition process in the sense of secondary recrystallization. However, if I ₁ / I ₀ is more than 40/100, it may be because the amount of Mg ₂ SiO ₄ generated relative to FeAl ₂ O ₄ is relatively insufficient, or some defects are observed on the film surface, and the uniformity of appearance is observed. Slightly deteriorated.

Next, FIG. 5 shows the relationship between I ₁ / I ₀ , I ₂ / I ₀ and the properties of the magnetic film. From this figure, the region where extremely excellent magnetic and coating characteristics can be obtained is represented by the following formulas (1) and (2): 3/100 ≦ I ₁ / I ₀ ≦ 40/100 --- (1) 3/100 ≦ I ₂ / I ₀ ≤40 / 100 --- (2) However, it can be seen that the range satisfies the relationship of I ₁ / I ₀ + I ₂ / I ₀ ≤50 / 100. Again,
Since the magnetic flux density (B ₈ ) was improved in this region,
Probably, the effect of improving the magnetic flux density (B ₈ ) by the influence on the secondary recrystallization process involving the formation of FeAl ₂ O ₄ and TiN is considered to be large.

When no TiN is produced (I
₂ / I ₀ = 0), the iron loss is degraded by the generation of FeAl ₂ O ₄ , and the generation of FeAl ₂ O ₄ is advantageous for the reduction of the iron loss when TiN is generated. It is obvious at a glance. Note that I ₁ / I ₀ > 40/100 or I ₂ / I ₀ > 40
In the range of / 100 or I ₁ / I ₀ + I ₂ / I ₀ > 50/100, the generation of Mg ₂ SiO ₄ in the forsterite coating is relatively insufficient, and some defects are present on the coating surface. The appearance uniformity tended to be slightly inferior.

From the above experimental results, the forsterite coating is mainly composed of Mg ₂ SiO ₄ , FeAl ₂ O ₄ and TiN. In particular, the intensity I of the Mg ₂ SiO ₄ (131) peak by thin film X-ray diffraction on the coating surface is ₀ , intensity I _{1 of} FeAl ₂ O ₄ (111) peak, TiN (200)
The peak intensity I ₂ is given by the following formula (1), (2) 3/100 ≦ I ₁ / I ₀ ≦ 40/100 --- (1) 3/100 ≦ I ₂ / I ₀ ≦ 40/100- -(2) However, it was clarified that when the relationship of I ₁ / I ₀ + I ₂ / I ₀ ≦ 50/100 was satisfied, both excellent magnetic properties and coating properties could be obtained. .

Next, the preferred composition range of the steel sheet according to the present invention will be described. The component composition of the silicon steel slab targeted in the present invention is as follows: C: 0.03 to 0.12%, Si:
2.0 to 4.5%, sol. Al: 0.005 to 0.05% and N: 0.00
It is necessary to contain 3 to 0.012%. sol. Al and N are necessary to form an AlN inhibitor, and for good secondary recrystallization, sol. Al: 0.00
It must be 5 to 0.05% and N: 0.003 to 0.012%.
It should be noted that if the amount exceeds this, AlN becomes coarse and the suppressing power is lost, while if less than this, the amount of AlN becomes insufficient. Also,
Al is also required as a raw material of FeAl ₂ O ₄ formed in the forsterite film. C is an important component for improving the crystal structure by utilizing the α-γ transformation during hot rolling. If the content is less than 0.03%, a good primary recrystallized structure cannot be obtained. On the other hand, if the content exceeds 0.12%, decarburization becomes difficult, decarburization becomes poor, and magnetic properties deteriorate, so 0.03 to 0.12%
And Si is an important component in increasing the electrical resistance of products and reducing eddy current loss. If the content is less than 2.0%, the crystal orientation is impaired by the α-γ transformation during the final annealing, while if it exceeds 4.5%, there is a problem in the cold rolling property. Therefore, the content is limited to 2.0 to 4.5%.

In addition, if necessary, Mn: 0.02 to 0.20
%, At least one selected from S and Se: 0.01
0 to 0.040%, Sb: 0.01 to 0.20%, Cu: 0.01 to 0.20%,
Mo: 0.005 to 0.10%, Sn: 0.02 to 0.30%, Ge: 0.02 to 0.
30%, Ni: 0.01-0.50%, Cr: 0.05-0.5%, P: 0.00
2 to 0.30%, Nb: 0.003 to 0.10%, V: 0.003 to 0.10%
And Bi: each component can be contained in the range of 0.005 to 0.20%. Mn, Se and S also function as inhibitors, but when the Mn content is less than 0.02% or the S or Se content alone or the total content is less than 0.010%, the inhibitor function is insufficient, while the Mn content is 0.20% Exceeds or S
If the total amount of S and Se exceeds 0.040%, the temperature required for heating the slab is too high to be practical, so Mn is 0.02 to 0.20%, and S and Se are single or total of 0.010 to It is preferably in the range of 0.040%.

In order to further improve the magnetic flux density, it is possible to add Sb, Cu, Sn, Ge, Ni, P, Nb and V alone or in combination. However,
If the content of Sb exceeds 0.20%, the decarburization property deteriorates, whereas if it is less than 0.0l%, there is no effect, so the content of Sb is 0.1%.
It is preferred to be about 01 to 0.20%. Cu has a content of 0.
If it exceeds 20%, the pickling property deteriorates, while if it is less than 0.01%, there is no effect, so its content is preferably about 0.01 to 0.20%. If the content of Sn and Ge exceeds 0.30%, a good primary recrystallized structure cannot be obtained, and if the content is less than 0.02%, there is no effect. Therefore, the respective contents are preferably set to about 0.02 to 0.30%. If the content of Ni exceeds 0.50%, the hot strength decreases, while if it is less than 0.01%, there is no effect, so the content is preferably about 0.01 to 0.50%. If the content of P exceeds 0.30%, a good primary recrystallized structure cannot be obtained, while if it is less than 0.002%, there is no effect, so the content is preferably about 0.002 to 0.30%. If the content of Nb and V exceeds 0.10%, the decarburization property is deteriorated, whereas if it is less than 0.003%, there is no effect. Therefore, the content of each is preferably about 0.003 to 0.10%.

Further, Mo can be added to improve the surface properties. However, if the content exceeds 0.10%, the decarburization property deteriorates, while if it is less than 0.005%, there is no effect, so the content is preferably about 0.005 to 0.10%. Cr is effective for further improving the film properties. However, if the content is less than 0.05%, no remarkable improvement effect is obtained, while if it exceeds 0.50%, the magnetic properties are deteriorated. Therefore, the content of Cr is preferably about 0.05 to 0.50%.

Further, Bi is an element useful for greatly improving magnetic properties and obtaining a material having a high magnetic flux density. However, if the content exceeds 0.20%, a good primary recrystallization structure cannot be obtained, and no improvement in magnetic flux density can be seen.
On the other hand, if it is less than 0.005%, the effect of its addition is poor,
Its content is preferably about 0.005 to 0.20%.
However, the addition of Bi degrades the film properties, so it is effective to add Cr together with the improvement. In this case, the amount of Cr may be in the range of 0.05 to 0.50% described above.

Next, the manufacturing conditions of the grain-oriented silicon steel sheet to which the present invention is applied will be described. Utilizing a steelmaking method conventionally used, molten steel adjusted to the above-mentioned preferred component composition is cast by a continuous casting method or an ingot-forming method, and if necessary, a slab is sandwiched by a lumping step, and then 1100 Slab heating is performed in a temperature range of 〜1450 ° C., followed by hot rolling. Next, after performing hot-rolled sheet annealing as necessary, a cold-rolled sheet having a final thickness is obtained by cold rolling once or twice or more with intermediate annealing. In the final cold rolling, it is desirable to perform at least one or more passes of rolling in which the temperature of the steel sheet immediately after the rolling roll exit side becomes 150 to 350 ° C.

[0037] Then, although not performing decarburization annealing, pickling weight loss values of the subscale formed by removing charcoal pure in this invention 0.3 g / m ² or less, -0.05 and V ₃₄ value + 0.05 ( It is important to keep it in the range of V). For this purpose, for example, from normal temperature to 750 ° C, the average heating rate is 12 to 35 ° C / s, and then from 750 ° C to the soaking temperature, the average heating rate: 1
The temperature rises at up to 10 ° C / s, and the degree of oxidation of the atmosphere (P (H
_{2 O) / P (H 2} ); but a ratio) of the steam partial pressure to hydrogen partial pressure of the atmosphere is preferably performed in a condition of from 0.35 to 0.50, in essence, above the pickling weight loss value and the V ₃₄ value Any condition can be used as long as the decarburization firing condition can be controlled within the range described above. The soaking temperature is preferably in the range of 800 to 900 ° C. This is because, even if the soaking temperature is lower or higher than this, the time required for decarburization becomes impractical considering the actual operation. Further, the amount of subscale is preferably 0.4 to 0.8 g / m ² in terms of the basis weight of oxygen (per side) of the steel sheet. , In less than 0.4 g / m ^2, hardly favorable coat is formed to subscale as the raw material of forsterite is insufficient, whereas 0.8 g / m ² by weight, is forsterite film excessively generated because This is because the space factor is reduced due to the increase in thickness. After the decarburizing annealing, a treatment for nitriding the steel sheet at about 30 to 200 ppm may be performed.

On the surface of the steel sheet subjected to the decarburizing annealing, a sintering agent containing magnesia as a main component is applied in a slurry state, and then dried. Here, the magnesia used for the annealing separator is a hydrated amount (after hydration at 20 ° C for 6 minutes, 1000 ° C,
It is advantageous to use those having a (loss by one-hour ignition) in the range of 1 to 4%. This is because the hydration of MgO is 1
If the amount is less than 4%, the formation of the forsterite film becomes insufficient, while if the amount exceeds 4%, the amount of water carried between the coil layers becomes too large, or the generation of TiN becomes insufficient. The citric acid activity at 30 ° C (CAA40) is
A time of 45 seconds to 120 seconds is preferred. The reason is that if the duration is less than 45 seconds, the reactivity is too strong and forsterite is rapidly generated and easily peels off, while if the duration is longer than 120 seconds, the reactivity is too weak and the production of forsterite does not proceed. Further, it is preferable to use one having a BET (specific surface area) of 12 to 40 m ² / g. At less than 12 m ² / g, the reactivity is so weak that forsterite formation does not proceed, while 40 m ² / g
If the amount exceeds / g, the reactivity is too strong, and forsterite is rapidly generated and easily peeled off.

It is preferable that the amount of the burnt separating agent applied is in the range of 4 to 10 g / m ² per one surface of the steel sheet. The reason is that when the coating amount is less than 4 g / m ² , forsterite is insufficiently generated, while when it exceeds 10 g / m ² , almost no TiN is generated. Further, a Ti oxide or a Ti compound which becomes a Ti oxide by heating is added to the incineration separating agent by adding TiO ₂ in terms of TiO ₂ to magnesia: 100 parts by weight.
It is important that the content be in the range of 2020 parts by weight. this
Ti compound is TiN produced in forsterite coating.
Is a source of Ti. Examples of Ti oxides or Ti compounds which become Ti oxides by heating include TiO ₂ , TiO _2
3 · H ₂ 0, TiO · (OH) ₂ , Ti (OH) _{4 and the} like. In addition, if the amount of Ti oxide in the incineration separator or the amount of Ti compound which becomes Ti oxide by heating is less than 2.0 parts by weight with respect to 100 parts by weight of magnesia in terms of TiO ₂ , the generation of TiN is insufficient. And the effect of improving magnetic properties and film properties is poor.
On the other hand, if it exceeds 20 parts by weight, the amount of magnesia becomes relatively small, and the forsterite formation reaction does not proceed.

It should be noted, further for the purpose of improving uniformity, oxides such as _{SnO 2, Fe 2 0 3,} CaO during annealing separator, sulfides such as MgSO ₄ and SnSO ₄ coating-magnetic properties, Or Sr
One or more of Sr compounds such as SO ₄ and Sr (OH) ₂ .8H ₂ O may be added alone or in combination. In particular, adding 0.5 to 5 parts by weight of Sr compound in terms of Sr with respect to 100 parts by weight of magnesia effectively acts to form both FeAl ₂ O ₄ and TiN in the forsterite film. On the contrary, B-based compounds such as Na ₂ B ₄ O ₇ and Sb
Sb-based compounds such as ₂ O ₃ and Sb ₂ (SO ₄ ) ₃ are not preferable because they hinder the formation of FeAl ₂ O ₄ in the forsterite film and facilitate the formation of MgAl ₂ O ₄ .

In addition, in order to form TiN, it is preferable that the winding tension after application of the separating agent is 29.4 to 245 MPa. The reason is that if the winding tension is less than 29.4 MPa, the film formed is almost forsterite and hardly generates TiN, while if it exceeds 245 MPa, TiN is generated, but the amount of FeAl ₂ O ₄ generated is insufficient. As a result, the uniformity of the coating deteriorates.

After that, the secondary recrystallization annealing and the purification annealing (final finish annealing) are performed. In this purification annealing, first, the nitrogen concentration is 15 vol% in a temperature range of 1050 ° C. or more for at least 3 hours. Annealing is performed in the above-described non-oxidizing atmosphere, and then in a hydrogen atmosphere having a nitrogen concentration of less than 2 vol% in a temperature range of 1150 to 1250 ° C. for at least 2 hours. That is, it is important to introduce nitrogen into the atmosphere at a temperature of 1100 ° C. or higher, which is the temperature at which TiO ₂ starts to decompose, in order to facilitate generation of TiN in the first half of the purification and inking. At this time, if the nitrogen concentration in the atmosphere is less than 15 vol%, the generation of TiN becomes insufficient, so that the content is set to 15 vol% or more. If the annealing time is less than 3 hours, the generation of TiN becomes insufficient, so the annealing time is 3 hours or more. The remaining atmosphere components may be non-oxidizing in order to form TiN preferentially, and specific examples include a hydrogen atmosphere and an inert gas atmosphere. In addition, the temperature in the latter half of the purification annealing is 1150 ℃
If the temperature is less than 1250 ° C., the removal of S or Se becomes insufficient and the magnetic properties are deteriorated. On the other hand, if the temperature exceeds 1250 ° C., the hot strength is reduced, the coil shape is deteriorated, and winding cannot be performed.
The temperature should be in the range of 50 to 1250 ° C. If the nitrogen concentration is 2 vol% or more or the annealing time is less than 2 hours, S or Se
Since the removal of these elements becomes insufficient and the magnetic properties deteriorate, the nitrogen concentration in the latter half of the purification and annealing is set to less than 2 vol% and the annealing time is set to 2 hours or more.

Finally, the unit weight (kg) and the unit time of the steel sheet
(h) The amount of ambient gas introduced per 100 × 10 ^{-6 to} 2000 ×
It is important that it is about 10 ^-6 m ³ / (kg · h). The reason is that if the atmospheric gas introduction amount is less than 100 × 10 ^-6 m ³ / (kg ・ h), gas circulation between coil layers will be insufficient,
Insufficient production of TiN and poor uniformity of the coating. On the other hand, if the gas introduction amount is more than 2000 × 10 ^-6 m ³ / (kg · h), not only is the economic efficiency inferior, but also especially in the outer winding part of the coil. TiN in the coating
Is hardly generated.

As described above, in order to generate TiN in the forsteritic film, it is necessary to (a) hydrate magnesia;
It is important to properly control (b) the amount of the separating agent applied, (c) the winding tension of the steel sheet after applying the separating agent, and (d) the atmosphere and gas flow rate during purification and sintering. By doing so, FeAl ₂ O ₄
Both of TiN could be formed.

Thereafter, a phosphate insulating coating, preferably an insulating coating having tension, is applied to obtain a product. Further, a known magnetic domain refining treatment may be performed after the final cold rolling, the final finish annealing, or the insulating coating, which is effective for further reducing iron loss.

[0046]

EXAMPLES Example 1 C: 0.068%, Si: 3.45%, Mn: 0.069%, sol.
025%, N: 0.0089%, Se: 0.020%, Cu: 0.12% and Sb: 0.040% A total of 10 steel slabs (each slab weight is 10t) were heated at 1430 ° C for 30 minutes. Then, a hot-rolled sheet having a thickness of 2.5 mm was formed by hot rolling. Then
After hot-rolled sheet annealing at 1000 ° C for 1 minute, the first cold-rolling makes the thickness: 1.8 mm intermediate thickness. After 1100 ° C, 1-minute intermediate annealing, the second cold-rolling gives the final thickness: Finished to 0.26mm. In this case, the temperature of the steel sheet immediately after the roll exit side was
Rolling to 200 ° C. or more was performed in two passes. Then, H ₂ −
Decarburization baking at 830 ° C. was performed in an H ₂ O—N ₂ atmosphere. At this time, the rate of temperature rise to 750 ° C and the rate of temperature rise from 750 ° C to 830 ° C were changed, and the oxidizing potential (P (H ₂ O) / P (H ₂ )) of the sootropic atmosphere was 0.2 to by varying in the range of 0.7, and the pickling weight loss value and the V ₃₄ value of decarburization annealed sheet subscale varied as shown in Table 1. Also,
Change the soaking time during decarburization annealing and the conditions for electrolytic degreasing (including before and after) after final cold rolling (before decarburization annealing), etc., and adjust the oxygen basis weight (per side) to 0.4 g / m ² or more. , And 0.8 g / m ² or less. Thereafter, the treatment was performed under the conditions shown in Table 1. The common conditions in the subsequent steps are as follows: magnesia: 10 parts by weight of TiO ₂ and 100 parts by weight of Sr compound for 100 parts by weight of Sr compound.
1 part by weight of the incinerated separating agent was applied to the surface of the steel sheet, and then heated to 850 ° C in a nitrogen atmosphere, and then 12 ° C in an atmosphere of 20 vol% nitrogen and 80 vol% hydrogen. A second recrystallization annealing is performed at a rate of 1050 ° C./h at a rate of 1160 ° C., 5 ° C. in a hydrogen atmosphere having a nitrogen concentration of less than 2 vol%.
That is, time purification annealing was performed. Then, after such purification annealing, a coating containing magnesium phosphate and colloidal silica as main components was applied.

The magnetic properties (magnetic flux density B ₈ , iron loss W _17/50 ), bending adhesion of the coating, and appearance of the coating were investigated for each product coil thus obtained. The bending adhesion of the coating was evaluated by wrapping a test piece around a round bar having various diameters at intervals of 5 mm and evaluating the minimum diameter at which the coating did not peel. Further, a thin film X-ray measurement of the film surface was performed, and the Mg ₂ SiO ₄ (131) peak I ₀ , Fe
The intensity of Al ₂ O ₄ (111) peak I ₁ , TiN (200) peak I ₂
The presence or absence of the MgA1 ₂ O ₄ (311) peak was also investigated. Table 2 summarizes the obtained results.

[0048]

[Table 1]

[0049]

[Table 2]

As is apparent from Table 2, according to the present invention, the main component of the forsterite coating is Mg ₂ SiO ₄ , FeAl ₂ O ₄
And those mainly composed of TiN show extremely excellent film properties and magnetic properties.

Example 2 C: 0.065%, Si: 3.26%, Mn: 0.068%, sol.
A total of 10 steel slabs each containing 024%, N: 0.0083%, Se: 0.018%, Cu: 0.10% and Sb: 0.025% (each slab weight is 10t) are heated at 1430 ° C for 30 minutes, respectively. Then, a hot-rolled sheet having a thickness of 2.7 mm was formed by hot rolling. Then
After the hot-rolled sheet was annealed at 1000 ° C for 1 minute, the first cold rolling was performed to obtain an intermediate thickness of 1.9 mm. After the intermediate annealing at 1100 ° C for 1 minute, the final thickness was obtained by the second cold rolling. Finished to 0.34mm. In this case, the temperature of the steel sheet immediately after the roll exit side was
One pass of rolling at 220 ° C. was performed. Then, H ₂ -H ₂ O
Decarburization annealing at 850 ° C. was performed in a —N ₂ atmosphere. At this time, the rate of temperature rise to 750 ° C and the rate of temperature rise from 750 ° C to 850 ° C were changed, and the oxidizing potential (P (H ₂ O) / P (H ₂ )) of the sootropic atmosphere was set to 0.2 to by varying in the range of 0.7, and the de-charcoal pickling weight loss value of the net plate subscale and V ₃₄ value was varied as shown in Table 3. Also, the soaking time during decarburization annealing and the conditions of electrolytic degreasing (including the presence or absence) after final cold rolling (before decarburization annealing) are appropriately changed, and the basis weight of oxygen (per side) is 0.4 g / m2. Adjustment was made to be ² or more and 0.8 g / m ² or less. Thereafter, the process was performed under the conditions shown in Table 3. The common conditions in the subsequent steps are as follows: magnesia: 100 parts by weight of TiO ₂ and 6 parts by weight of TiO ₂ were applied to the surface of the steel sheet, and then, the mixture was applied in a nitrogen atmosphere.
Following the holding treatment at 850 ° C for 25 hours, nitrogen: 25 vol%,
Hydrogen: After performing secondary recrystallization baking in which the temperature is raised to 1050 ° C. at a rate of 10 ° C./h in an atmosphere of 75 vol%, the nitrogen concentration becomes 2%.
That is, purification annealing was performed at 1200 ° C. for 3 hours in a hydrogen atmosphere of less than vol%. And after such purification annealing,
A coating mainly composed of magnesium phosphate and colloidal silica was applied.

The magnetic properties (magnetic flux density B ₈ , iron loss W _17/50 ), bending adhesion of the coating and appearance of the coating were investigated for each of the product coils thus obtained. The thin film X on the surface of the coating
Line measurement, and the Mg ₂ SiO ₄ (131) peak I ₀ , FeAl ₂ O ₄ (111)
Peak I ₁ , TiN (200) Intensity of peak I ₂ and MgA1 ₂ O ₄ (31
1) The presence or absence of a peak was also investigated. Table 4 summarizes the results obtained.

[0053]

[Table 3]

[0054]

[Table 4]

As is clear from Table 4, according to the present invention, the forsterite coating is mainly composed of Mg ₂ SiO ₄ , FeAl ₂ O ₄
And those mainly composed of TiN show extremely excellent film properties and magnetic properties.

Example 3 Silicon-containing slabs having various component compositions shown in Table 5 were prepared. These steel slabs were heated at 1430 ° C. for 30 minutes and then hot-rolled into hot-rolled 2.3 mm thick sheets. Then 1000
After the hot-rolled sheet was annealed at ℃ for 1 minute, the first cold rolling was performed to obtain an intermediate thickness of 1.7 mm. After the intermediate annealing at 1050 ° C. for one minute, the final cold-rolled thickness was 0.22. mm. At this time, the temperature of the steel sheet immediately after
Rolling to at least 00 ° C. was performed in two passes. Then, H ₂ -H ₂
Decarburization annealing at 840 ° C. was performed in an O—N ₂ atmosphere. At this time, the rate of temperature rise up to 750 ° C and the rate of temperature rise from 750 ° C to 840 ° C are changed, and the oxidizing potential (P (H ₂ O) / P (H ₂ )) of the sootropic atmosphere is set to 0.2 to by varying in the range of 0.7, and the pickling weight loss value and the V ₃₄ value of decarburization annealed sheet subscale varied as shown in Table 6. Also, the soaking time during decarburization annealing and the conditions of electrolytic degreasing (including the presence or absence) after final cold rolling (before decarburization annealing) are appropriately changed, and the basis weight of oxygen (per side) is 0.4 g / m2. Adjustment was made to be ² or more and 0.8 g / m ² or less. In Table 5, the coil having the F composition was subjected to a nitriding treatment after the decarburizing annealing to reduce the nitrogen content to 200 ppm.
Thereafter, the treatment was performed under the conditions shown in Table 6. The common conditions in the subsequent steps are as follows. Magnesia: 100 parts by weight, 8 parts by weight of TiO ₂ and 2.5 parts by weight of an Sr compound in terms of Sr are applied to the surface of the steel sheet, and thereafter, Following a 20-hour hold at 850 ° C in a nitrogen atmosphere, nitrogen: 25 v
ol%, hydrogen: 1050 at a rate of 10 ° C / h in an atmosphere of 75 vol%
After performing the secondary crystal annealing to raise the temperature to ° C., purifying annealing was performed at 1180 ° C. for 3 hours in a hydrogen atmosphere having a nitrogen concentration of less than 2 vol%. Then, after such purification annealing, a coating containing magnesium phosphate and colloidal silica as main components was applied.

The magnetic properties (magnetic flux density B ₈ , iron loss W _17/50 ), bending adhesion of the coating and appearance of the coating were investigated for each product coil thus obtained. The thin film X on the surface of the coating
Line measurement, and the Mg ₂ SiO ₄ (131) peak I ₀ , FeAl ₂ O ₄ (111)
Peak I ₁ , TiN (200) Intensity of peak I ₂ and MgA1 ₂ O ₄ (31
1) The presence or absence of a peak was also investigated. Table 7 summarizes the results obtained.

[0058]

[Table 5]

[0059]

[Table 6]

[0060]

[Table 7]

As is clear from Table 7, according to the present invention, the main component of the forsterite coating is Mg ₂ SiO ₄ , FeAl ₂ O ₄
In the case of using TiN or TiN as a main component, extremely excellent film properties and magnetic properties were obtained.

[0062]

According to the present invention, the forster
The main body of the light coating is Mg_TwoSiO_Four , FeAl _TwoO_Four And TiN
By doing so, extremely excellent magnetic properties and coating characteristics
Both sexes can be obtained at the same time.

[Brief description of the drawings]

Figure 1: Mg ₂ SiO ₄ and MgAl ₂ 0 _{4 in} forsterite coating
FIG. 4 is a diagram showing an example of generation of.

FIG. 2 is a view showing an example of generation of Mg ₂ SiO ₄ , FeAl ₂ O ₄ and TiN by thin-film X-ray diffraction on a forsterite coating film surface.

FIG. 3 is a diagram showing the effect of the temperature rise rate during decarburization annealing on magnetic properties and coating properties.

[4] Mg ₂ SiO ₄ (131) peak intensity I ₀ and TiN (200) relationship strength I ₂ peaks _{5/100 ≦ I 2 / I 0 ≦} 10/10
FIG. 4 is a diagram showing the effect of the ratio I ₁ / I ₀ of the intensity I ₁ of the FeAl ₂ O ₄ (111) peak to the intensity I ₀ of the Mg ₂ SiO ₄ (131) peak on the magnetic properties when the ratio is ₀ . .

FIG. 5 shows the intensity I _{0 of} the Mg ₂ SiO ₄ (131) peak, FeAl ₂ O ₄ (111)
FIG. 4 is a diagram showing the influence of the intensity ratios I ₁ / I ₀ and I ₂ / I ₀ between the peak intensity I ₁ and the TiN (200) peak intensity I ₂ on the magnetic and coating characteristics.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 38/00 303 C22C 38/00 303U 38/06 38/06 38/60 38/60 (72) Inventor Atsuto Honda 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. F-term in steel works (reference) 4K026 AA03 AA22 BA02 BA11 BB05 BB10 CA16 CA18 4K033 AA02 BA01 BA02 CA01 CA02 CA03 CA04 CA07 CA08 CA09 FA01 FA12 HA01 HA03 HA05 JA05 LA01 LA04 NA01 NA02 NA03 PA04 RA04 SA02 TA03 5E041AB HA02

Claims (2)

[Claims] 1. A grain-oriented silicon steel sheet having a forsterite coating on a surface thereof, wherein the forsterite coating is mainly composed of Mg ₂ SiO ₄ , FeAl ₂ O ₄ and TiN. Grain-oriented silicon steel sheet with excellent properties and coating properties. 2. A grain-oriented silicon steel sheet having a forsterite coating on its surface, wherein the forsterite coating is mainly composed of Mg ₂ SiO ₄ , FeAl ₂ O ₄ and TiN, and a thin film X on the coating surface. When the intensity of the Mg ₂ SiO ₄ (131) peak by line diffraction is I ₀ , the intensity of the FeAl ₂ O ₄ (111) peak is I ₁ , and the intensity of the TiN (200) peak is I ₂ , (1), (2) 3/100 ≦ I 1 / I 0 ≦ 40/100 --- (1) 3/100 ≦ I 2 / I 0 ≦ 40/100 --- (2) where, I ₁ / A grain-oriented silicon steel sheet having excellent magnetic properties and coating properties, satisfying the relationship of I ₀ + I ₂ / I ₀ ≦ 50/100.