JP2001158919A - Method for producing grain oriented silicon steel sheet excellent in magnetic property and film characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for advantageously producing a grain oriented silicon steel sheet good in both magnetic properties and film characteristics even in the case slab heating temperature is made the low one equal to that of common steel in the production of a general purpose grain oriented silicon steel sheet requiring the reduction of the cost. SOLUTION: In the method for producing a grain oriented silicon steel sheet in which a silicon steel slab having a componential composition containing, by weight, 0.005 to 0.100% C, 2.0 to 4.5% Si and 0.03 to 2.50% Mn, in which the contents of N and S are suppressed in accordance with the expression of [ppm N]2+[ppm S]2<=6400 and moreover containing one or two or more kinds selected from Sb, Sn, Cr, Cu and P is heated to <=1260 deg.C, is thereafter hot-rolled, is next subjected to hot rolled sheet annealing at need, is subjected to cold rolling for one time or for two or more times including process annealing to control its sheet thickness into the final one, is furthermore subjected to decarburizing annealing, is subsequently applied with a separation agent for annealing and is then subjected to finish annealing, the temperature rising rate from 600 to 750 deg.C in the decarburizing annealing is controlled to >=15 deg.C/s, and also, the ratio of the partial pressure of water vapor to the partial pressure of hydrogen in a soaking stage of the decarburizing annealing, i.e., atmospheric oxidizable P(H2O)/P(H2) is controlled to the range of <=0.6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stably producing a grain-oriented electrical steel sheet, particularly a general-purpose grain-oriented electrical steel sheet having excellent magnetic properties and coating properties.

[0002]

2. Description of the Related Art Grain-oriented silicon steel sheets are mainly used as iron core materials for transformers and other electric equipment, and it is important that they have excellent magnetic properties such as magnetic flux density and iron loss value. Therefore, a slab having a thickness of 100 to 300 mm is heated to a high temperature and then hot-rolled, and then the hot-rolled sheet is subjected to one or intermediate annealing.
A complicated process of taking a final thickness by cold rolling more than once, applying an annealing separator after decarburizing annealing, and then performing a final finish annealing for the purpose of secondary recrystallization and purification. . In order to improve the magnetic properties, it is necessary to grow crystal grains of the {110} <001> orientation in which the <001> axis, which is the easy axis, is aligned with the rolling direction in the secondary recrystallization in the finish annealing step. is important.

In order to effectively promote the secondary recrystallization accumulated in the {110} <001> orientation, a dispersed phase called an inhibitor which suppresses the growth of primary recrystallized grains is dispersed in a uniform and appropriate size. It is effective to do so. The action of this inhibitor suppresses the growth of primary recrystallized grains during final finish annealing, but only the grains with the {110} <001> orientation, which has the highest dominance of grain growth, have priority over other orientations. It grows. Therefore, the inhibitory force of the inhibitor must be controlled so that only grains having the {110} <001> orientation can grow and the growth of other grains can be stopped.

[0004] Such inhibitors include MnS, MnS
e, such as sulfides, Se compounds or nitrides, such as AlN and VN, which have extremely low solubility in steel are used. After that, a method of precipitating finely in a subsequent step has been adopted. The slab heating temperature for sufficiently dissolving the inhibitor is about 1400 ° C., which is about 200 ° C. higher than the slab heating temperature of ordinary steel. Such high-temperature slab heating has the following disadvantages. (A) The unit energy consumption is high due to high-temperature heating. (A) Melt scale is easily generated and slab dripping is easily generated. (C) Excessive decarburization of the slab surface layer occurs.

In order to solve the above problems (a) and (c), an induction heating furnace dedicated to directional silicon steel has been proposed. However, an increase in energy cost is a new problem.

In order to solve the above-mentioned problem (A), many studies have been made to reduce the temperature of a directional silicon steel slab to a low temperature. In other words, a decrease in the slab heating temperature leads to a shortage of the solid solution amount of the inhibitor component, and inevitably causes a decrease in the suppressing power. It has been developed. For example, Japanese Patent Application Laid-Open No. 57-207114 discloses a technique of nitriding during decarburizing annealing, and Japanese Patent Application Laid-Open No. 62-70521 discloses a technique of specifying final annealing conditions and performing intermediate nitriding during final annealing. Have been. Further, JP-A-62-4031
No. 5 discloses a method of controlling an inhibitor to an appropriate state by nitriding in a later step even if Al and N are not dissolved in slab during heating.

[0007] However, the method of performing nitriding in the middle before the start of the final annealing requires new equipment and increases the cost, and the nitriding during the final annealing is difficult to control. Remains.

By the way, consumers of grain-oriented electrical steel sheets place great importance on film properties as well as magnetic properties. This is because the coating of the grain-oriented electrical steel sheet has a role of improving the building factor and a role of changing the magnetostriction and distortion sensitivity that affect noise, as well as the role of maintaining insulation in the core of the transformer.

Japanese Patent Application Laid-Open No. 7-76736 discloses a technique on the premise that low-temperature slab heating is performed for controlling the film characteristics. That is, Cl and / or SO ₃ are added to the steel sheet after the decarburization / nitriding treatment as 0.15 to 0.15
By applying magnesia containing 2.0% and performing finish annealing, a grain-coated electrical steel sheet with excellent glass coating and magnetic properties can be obtained.
20 ° C. / h or less, 900 ° C. or more N ₂ for heating the atmosphere gas 25
It is disclosed that by setting the percentage, a further improvement in glass coating quality and magnetic properties can be obtained. The publication also discloses that by adding 0.1 to 7.5 parts by weight of at least one of Ti, Sb and B compounds as an additive to magnesia, a grain-oriented electrical steel sheet having extremely excellent coating properties can be obtained. Have been.

[0010] However, since the film properties greatly change depending on the state of formation of the surface oxide film due to the difference in the component composition of the material and the processing steps, and the physical properties of magnesia, sufficient reactivity is obtained at the time of film formation. It was something I couldn't say yet.

[0011]

SUMMARY OF THE INVENTION Therefore, the present invention
In the production of general-purpose grain oriented silicon steel sheets that require cost reduction, even if the slab heating temperature is as low as that of ordinary steel, it is advantageous to produce grain-oriented electrical steel sheets with good magnetic properties and coating properties. The aim is to propose a method.

[0012]

That is, the gist of the present invention is as follows. (1) C: 0.005 to 0.100 wt%, Si: 2.0 to 4.5 wt% and Mn: 0.03 to 2.50 wt%, and the content of N and S is determined according to [ppm N] ² + [ppm S] ² ≦ 6400. Sb, Sn, Cr, Cu and P, a silicon steel slab having a component composition containing at least one selected from the group consisting of one or more, heated to a temperature of 1260 ° C. or lower, then hot-rolled, Hot rolled sheet annealing is performed as necessary, and the final thickness is obtained by cold rolling twice or more once or intermediate annealing,
Furthermore, in a method for producing a grain-oriented electrical steel sheet in which an annealing separator is applied after decarburizing annealing and then finish annealing is performed, the rate of temperature rise from 600 ° C to 750 ° C in decarburizing annealing is controlled to 15 ° C / s or more. And the oxidizing atmosphere P (H ₂ O) / P (H ₂ ), which is the ratio of the partial pressure of water vapor to the partial pressure of hydrogen during the soaking process of decarburization annealing, is set to 0.
6 A method for producing a grain-oriented electrical steel sheet having excellent magnetic properties and coating properties, characterized by being controlled in the following range.

(2) In the above (1), MgO is the main component.
A method for producing a grain-oriented electrical steel sheet having excellent magnetic properties and coating properties, characterized by applying an annealing separator containing an Sr compound.

(3) The unidirectional electromagnetic device according to (1) or (2), wherein nitriding is performed after final cold rolling and before the start of secondary recrystallization. Steel plate manufacturing method.

(4) In the above (1), (2) or (3),
The random strength ratio of the pole density in the texture at the surface layer of the steel sheet after decarburization annealing is (222): 1.5 to 6.0 and (31).
0): A method for producing a grain-oriented electrical steel sheet having excellent magnetic properties and coating properties, satisfying 0.7 to 1.5.

Here, the random intensity ratio of the pole density in the texture is evaluated by the surface intensity measured by X-ray diffraction. Note that the random intensity ratio indicates the existence ratio of a specific direction. (Existence ratio of a portion having a specific direction in a measurement site) / (the direction in a virtual case where there is no orientation at all) Ratio of existing parts).

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An experiment which led to the present invention will be described below in detail. By the way, {110} <001
As described above, inhibitors for suppressing the growth of primary grains have been indispensable for secondary recrystallization of oriented grains. Attempts to produce grain-oriented electrical steel sheets without using inhibitors are disclosed in Japanese Patent Application Laid-Open Nos.
57635, JP-A-7-76732 and JP-A-7-76732.
No. 197126 discloses methods using tertiary recrystallization.However, since these methods use a difference in surface energy, the sheet thickness is limited to an extremely small thickness, which is not industrially suitable. Was.

On the other hand, in recent years, as an important point of secondary recrystallization development, attention has been paid to an azimuth difference angle in the primary recrystallized structure, that is, a minimum rotation angle for overlapping two directions, in addition to an inhibitor. It has become. It is reported in Acta Material 45 that grain boundaries (high-energy grain boundaries) with an azimuth difference angle of 20 to 45 ° play an important role. Based on this, grain-oriented electrical steel sheets without inhibitors Research has begun to flourish again. Under such a technical background, the inventors conducted the following experiment in which the aim was to lower the slab heating temperature and to significantly reduce the amount of nitride or sulfide contained as an inhibitor.

[Experiment 1] First, a grain-oriented electrical steel slab having a normal component composition of grain-oriented electrical steel except that N and S were not positively contained was subjected to a temperature of 1200 ° C., similar to ordinary steel.
When an experiment was conducted in which slab heating was performed, secondary recrystallization could not be generated.

[Experiment 2] Then, when Sb, which is a grain boundary segregation type inhibitor, was added as a reinforcing inhibitor unaffected by the slab heating temperature with the same component composition, secondary recrystallization occurred stably. . Furthermore, other than Sb, similar effects were observed for Sn, Cr, Cu and P.

Furthermore, as a result of examining the magnetic properties by changing the conditions in the middle of the manufacturing process in various ways, the atmosphere in the soaking process of decarburizing annealing was set to a low dew point (low oxidation), and the steel sheet after decarburizing annealing was Good magnetic properties were obtained when the oxygen weight was reduced, but when the oxygen weight after the decarburization annealing in a high dew point (highly oxidizing) atmosphere increased, the secondary It was found that although the crystal was formed, the orientation deviated from {110} <001> was likely to undergo secondary recrystallization, and the magnetic characteristics deteriorated.

On the other hand, as for the coating, when the decarburizing annealing atmosphere was highly oxidizing, a dense undercoating was formed, and the coating adhesion was improved. However, when the decarburizing annealing atmosphere was low oxidizing, the amount of the formed film was insufficient, and the adhesion of the film was deteriorated. Observation of the cross section of the coating at this time revealed that the interface between the base coating and the ground iron was flattened and easily peeled off, and portions where the anchor effect of the base coating was weak were frequently observed. Therefore, by controlling the decarburizing annealing atmosphere, it was not possible to achieve both the magnetic characteristics and the film characteristics.

[Experiment 3] In Experiment 2 described above, the atmosphere oxidizing property was changed during the soaking process of decarburizing annealing. The range where the magnetic properties were good was on the low oxidizing side and the range where the coating properties were good. There was no range satisfying both on the high oxidation side. Therefore, as a process condition affecting both the magnetic properties and the film properties, attention is paid to the heating rate in the heating process of decarburizing annealing, and the average heating rate is 600 to 750 for this heating rate.
The study was performed in the section of ° C. In Experiment 2, the heating rate was 8 ° C./s.

That is, as the heating rate in the heating process of the decarburization annealing was increased, secondary grains deviated from the {110} <001> orientation became more difficult to appear, and the magnetic properties were improved. Here, the results of investigating the texture of the surface layer of the steel sheet subjected to decarburizing annealing at various heating rates by polar density measurement (inverse measurement) by X-ray diffraction are shown in FIGS. As shown in FIGS. 1 to 3, as the heating rate increases, the main orientation (222) decreases, the secondary recrystallization nucleus (220) slightly increases, and (310) increases. I was
In the primary recrystallization texture, it is known that, when the (222) strength is too strong, secondary grains deviated from the {110} <001> orientation are likely to grow, but in the material of the present invention, decarburization is performed. By increasing the heating rate of annealing, (22
In place of (2), the (310) orientation increases,
It is considered that the generation of secondary grains having a misaligned orientation was suppressed and the magnetic properties were improved.

Further, when the heating rate is increased, the oxygen weight per unit area after the decarburizing annealing increases even with the same oxidizing property in the atmosphere. Therefore, it is possible to secure a sufficient oxygen weight per unit area to obtain good film properties. The range of the oxidizing atmosphere shifts to the lower oxidizing side. On the other hand, when the oxygen basis weight increases, secondary grains with misalignment tend to be generated as described above, but if the heating rate is increased, the primary recrystallized structure is improved and secondary grains with misalignment are improved. Since the occurrence is suppressed, it is possible to achieve both the magnetic characteristics and the film characteristics.

Further, regarding the further improvement of the film properties,
MgO result of studying a method of adding various auxiliary agents in the annealing separator composed mainly of the addition of _{Sr (OH) 2 · 8H 2} O Sr compound such as was very effective.

Next, the component composition and the production process of the target material of the present invention will be described in detail. First, the reasons for limiting each component of the component composition are shown below. C: 0.005 to 0.100 wt% C is an element necessary for improving the structure and stabilizing the secondary recrystallization. For that purpose, 0.005 wt% or more is required. However, if the content exceeds 0.100 wt%, the fracture during cold rolling increases, and the load of decarburizing annealing increases to lower the productivity. Therefore, the content is set to 0.100 wt% or less.

Si: 2.0 to 4.5 wt% Si is an essential element for increasing electric resistance and reducing iron loss. For this purpose, it is necessary to contain 2.0 wt% or more. If the content exceeds wt%, the processability deteriorates, and it becomes extremely difficult to manufacture and process the product.
4.5 wt% range.

Mn: 0.03 to 2.50 wt% Mn is an element necessary for increasing the electric resistance and improving the hot workability at the time of production, like Si. For this purpose, a content of 0.03 wt% or more is necessary. However, if it exceeds 2.50 wt%, γ transformation is induced to deteriorate magnetic properties. I do.

N and S: [ppm N] ² + [ppm S] ² ≦ 6400 In a normal grain-oriented electrical steel sheet, N forms a nitride such as AlN, and S forms a sulfide such as MnS. , Acts as an inhibitor. However, in the present invention, since the slab heating temperature is as low as that of ordinary steel, the excessive N and S contents make it difficult to form a solution of nitrides and sulfides, and secondary recrystallization does not occur or unevenness occurs. Cause secondary recrystallization.

Therefore, the allowable range of N and S under the condition that the slab heating temperature was 1260 ° C. or less was examined by experiments. That is, C: 0.04 wt%, Si: 3.0 wt%, Mn: 0.07 wt%,
The final plate thickness was 0.34 by varying the contents of N and S in the basic components of Al: 0.007 wt% and Sb: 0.02 wt%.
A grain-oriented electrical steel sheet with a slab heating temperature of 1260 ° C or less was manufactured, and the iron loss of the obtained steel sheet was investigated. FIG. 4 summarizes the results of the investigation into the relationship between the N and S contents and the iron loss of the product. That is, N and S are not independent, and it is found that regulation under the relational expression of [ppm N] ² + [ppm S] ² ≦ 6400 is extremely effective in improving product iron loss. .

The regulation by the above relational expression is more effective than the range where N and S are independently N ≦ 80 ppm and S ≦ 80 ppm.
The allowable range of N and S contents is narrow, and the simple sum N + S
Wider than the range of ≦ 80. Although the reason for this is not clear, it is considered that when nitrides and sulfides coexist, composite precipitates of both are also formed, which complicates the solution-forming behavior.

It should be noted that the Se compound used as an inhibitor as well as the nitride and the sulfide requires a high temperature for solution, and is not suitable for lowering the slab heating temperature. Therefore, no Se was added, or even 50
It is preferred to limit to less than ppm.

The inhibitor components include Sb, Sn, C
One or more selected from r, Cu and P can be used. These elements effectively act as inhibitors even under manufacturing conditions in which the slab heating temperature is as low as that of ordinary steel. In order to obtain this effect, it is desirable to add these elements at 0.001 wt% or more. On the other hand, if it exceeds 0.30 wt%, the mechanical properties such as bend characteristics of the product will deteriorate, so the upper limit should be 0.30 wt%. Is preferred.

The slab adjusted to the above components is subjected to slab heating and then hot-rolled into a hot-rolled coil according to a usual method. The slab heating temperature is set to 1260 ° C. or lower in order to reduce energy costs and protect the global environment. In recent years, a method of directly performing hot rolling after continuous casting without performing slab heating has been proposed. However, since the present invention is intended to reduce the slab heating temperature, its application can be advantageously performed. .

After the above-mentioned hot rolling, if necessary, a hot-rolled sheet is annealed and then subjected to cold rolling. Cold rolling is performed by a tandem rolling mill or a Sendzimir rolling mill. Rolling may be performed to the final thickness by one cold rolling, or rolling may be performed twice or more with intermediate annealing interposed therebetween. Here, the method of controlling the texture by raising the rolling temperature higher than the normal temperature and using dynamic strain aging during rolling and static strain aging between passes,
The present invention is also applicable.

Next, after cold rolling, decarburizing annealing is performed according to a conventional method, an annealing separator is applied, and final finishing annealing is performed. In order to improve both the magnetic properties and the film properties of the product, the heating rate of the decarburization annealing at 600-750 ° C should be 15 ° C / s or more, and the atmosphere in the soaking process should have low oxidizing properties. Specifically, it is necessary to make the atmosphere oxidizing P (H ₂ O) / P (H ₂ ), which is the ratio of the water vapor partial pressure to the hydrogen partial pressure, 0.6 or less. In order to form a stable film, it is preferable to apply an annealing separator containing MgO 2 as a main component and an Sr compound. Examples of the Sr compound include SrSO ₄ , Sr (H
O) ₂ · 8H ₂ O, may be used one or more selected from among SrCO ₃ and Sr (NO _{3) 2.} In addition,
Compounds other than the Sr compound can be contained as accessory components within a range not to impair the object of the present invention.

After the final finish annealing, an insulation coating is applied and baked as required, and further flattening annealing is performed to obtain a product. Also, after the final cold rolling and before the start of the secondary recrystallization, performing nitriding as required is effective as one means for appropriately controlling the grain growth suppressing force. Although the nitriding treatment has a disadvantage of increasing the manufacturing cost, it is one measure for lowering the slab heating temperature. Even in the nitriding treatment, the present invention provides good magnetic properties and coating properties. It is suitable for obtaining.

[0039]

EXAMPLES Example 1 A steel slab having a component composition of steel Nos.
After heating to ° C., it was hot-rolled to obtain a 2.2 mm thick hot-rolled coil. This hot-rolled coil was subjected to hot-rolled sheet annealing maintained at 1000 ° C. for 30 seconds, pickled, and then cold-rolled once by a tandem rolling mill to a thickness of 0.29 mm. After that, degreasing is performed, and 84
Decarburization annealing was performed at 0 ° C for 120 seconds. During the decarburizing annealing heating process, the heating rate in the section from 600 ° C to 750 ° C was controlled to 20 ° C / s, and the atmosphere oxidizing P (H ₂ O) /
(H ₂ ) was controlled to be 0.40.

After decarburizing annealing, an annealing separator was applied to perform final finish annealing. The annealing separator contains MgO as the main component,
Sr and (HO) ₂ · 8H ₂ O was used as the added 5 wt% as an auxiliary agent. After the final annealing, the unreacted separating agent was removed, an insulating coating containing magnesium phosphate containing colloidal silica as a main component was applied, and baked at 800 ° C. to obtain a product. An Epstein test piece was cut out from each product along the rolling direction, and the iron loss W _17/50 was measured.

As shown in Table 2, the slab having the component composition according to the present invention can provide a grain-oriented electrical steel sheet having good magnetic properties and coating properties, as shown in Table 2 showing the iron loss value and the coating adhesion.

[0042]

[Table 1]

[0043]

[Table 2]

Example 2 A steel slab having the composition of steel No. 1 shown in Table 1 was heated to 1150 ° C., and then hot-rolled into a hot-rolled coil having a thickness of 2.4 mm. Next, the hot-rolled coil was subjected to hot-rolled sheet annealing maintained at 1000 ° C. for 30 seconds, pickled, and then cold-rolled once by a Sendzimir rolling mill to a thickness of 0.34 mm. After that, degreasing is performed and 840
Decarburization annealing was performed at 120 ° C. for 120 seconds. Heating process of decarburization annealing
The heating rate in the section from 600 ° C to 750 ° C is 8 ° C / s, 16 ° C /
s and 24 ° C./s. Furthermore, the atmosphere oxidizing P (H ₂ O) / P (H ₂ ) during the soaking process of decarburizing annealing is 0.45,
Control was performed in three ways, 0.55 and 0.65.

After decarburizing annealing, an annealing separator was applied to perform final finish annealing. The annealing separator contains MgO as the main component,
Sr (HO) ₂ .8H ₂ O was added as an auxiliary agent in an amount of 5 wt% and was not added. Then, after the final annealing, the unreacted separating agent was removed, an insulating coating containing magnesium phosphate containing colloidal silica as a main component was applied, and the product was baked at 800 ° C. to obtain a product. From each product,
An Epstein test piece was cut out along the rolling direction, and the iron loss W _17/50 was measured.

After the decarburizing annealing, a part of the sample was collected,
The primary recrystallization texture near the surface layer was measured. The texture was evaluated by measuring the pole density of the steel sheet surface by X-ray diffraction.

Table 3 shows the iron loss values of the products, coating adhesion, (222) strength and (310) of the primary recrystallization texture.
By controlling the primary recrystallization texture within the scope of the invention according to the method of the present invention so as to show strength, a grain-oriented electrical steel sheet having both good magnetic properties and good coating properties was obtained.

[0048]

[Table 3]

Example 3 A steel slab having the composition of steel No. 5 shown in Table 1 was heated to 1230 ° C. and then hot-rolled into a hot-rolled coil having a thickness of 2.6 mm. Thereafter, the plate was pickled and subjected to a first cold rolling by a tandem rolling mill to a thickness of 1.5 mm. Next, after intermediate annealing at 1000 ° C. for 60 seconds was performed, acid washing was performed again, and second cold rolling to a thickness of 0.22 mm was performed using a Sendzimir rolling mill. Thereafter, a degreasing treatment was performed, followed by a decarburizing annealing at 840 ° C. for 120 seconds. Heating process of decarburizing annealing The heating rate in the section from 600 ° C to 750 ° C was controlled in three ways: 8 ° C / s, 16 ° C / s and 24 ° C / s. Atmospheric oxidizability during soaking process in decarburization annealing
P (H ₂ O) / P (H ₂ ) was controlled in three ways: 0.30, 0.50 and 0.70.

After the decarburizing annealing, nitriding annealing was performed at 750 ° C. for 30 seconds in a mixed gas of hydrogen, nitrogen and ammonia. Thereafter, an annealing separator was applied to perform a final finish annealing. The annealing separator contains MgO as the main component and SrSO ₄ as an auxiliary agent.
What added wt% was used.

After the final finish annealing, the unreacted separating agent is removed,
Mainly composed of magnesium phosphate containing colloidal silica
Baked at 800 ℃
The product. From each product, eps
Specimens are cut out and iron loss W _17/50 Was measured.

After the decarburizing annealing, a part of the sample was collected,
The texture near the surface layer was measured. The texture was evaluated by measuring the pole density of the steel sheet surface by X-ray diffraction.

According to the method of the present invention, the primary recrystallized texture was set within the range of the invention as shown in Table 4 showing the iron loss value, coating adhesion, and primary recrystallized texture (222) strength and (310) strength of the product. Thus, a grain-oriented electrical steel sheet having good magnetic properties and coating properties was obtained.

[0054]

[Table 4]

[0055]

According to the present invention, it has become possible to stably produce a grain-oriented electrical steel sheet having excellent magnetic properties and coating properties.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a (222) plane strength change accompanying a change in a heating rate during decarburization annealing.

FIG. 2 is a diagram illustrating a change in (220) plane strength with a change in a heating rate during decarburization annealing.

FIG. 3 is a diagram showing a change in (310) plane strength accompanying a change in a heating rate during decarburization annealing.

FIG. 4 is a diagram showing iron loss of a product when materials having different contents of N and S are used.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 38/60 H01F 1/16 B (72) Inventor Atsuto Honda 1-chome Mizushima Kawasaki-dori, Kurashiki City, Okayama Prefecture ( No address) F-term (reference) at Kawasaki Steel Corporation Mizushima Works 4K033 AA02 CA01 CA02 CA03 CA07 FA01 FA12 HA01 HA03 JA04 JA05 LA01 5E041 AA02 AA19 BC01 CA02 HB05 HB07 HB09 HB11 NN06 NN17 NN18

Claims (4)

[Claims] (1) C: 0.005 to 0.100 wt%, Si: 2.0 to 4.5 wt%, and Mn: 0.03 to 2.50 wt%, and the content of N and S is [ppm N] ² + [ppm S] ² ≦ 6400, and further hot-rolling a silicon steel slab having a component composition containing one or more selected from Sb, Sn, Cr, Cu and P to a temperature of 1260 ° C. or less,
Next, if necessary, hot-rolled sheet annealing is performed, the final sheet thickness is obtained by cold rolling once or twice or more with intermediate annealing interposed therebetween, and after decarburizing annealing, an annealing separator is applied, followed by finish annealing. In the method for producing grain-oriented electrical steel sheets, 60
The rate of temperature rise from 0 ° C to 750 ° C is controlled to 15 ° C / s or more, and the atmosphere oxidizing P (H ₂ O) / is the ratio of the partial pressure of water vapor to the partial pressure of hydrogen during the soaking process of decarburizing annealing. A method for producing a grain-oriented electrical steel sheet having excellent magnetic properties and coating properties, wherein P (H ₂ ) is controlled to a range of 0.6 or less. 2. The method according to claim 1, wherein MgO 2 is a main component and Sr is a main component.
A method for producing a grain-oriented electrical steel sheet having excellent magnetic properties and coating properties, characterized by applying an annealing separator containing a compound. 3. The method for producing a grain-oriented electrical steel sheet according to claim 1, wherein nitriding is performed after the final cold rolling and before the start of secondary recrystallization. . 4. The steel sheet according to claim 1, 2 or 3, wherein the random strength ratio of the pole density in the texture in the surface layer of the steel sheet after decarburizing annealing is (222): 1.5 to 6.0 and (310):
A method for producing a grain-oriented electrical steel sheet having excellent magnetic properties and film properties, satisfying 0.7 to 1.5.