JP2014095129A - Grain oriented silicon steel sheet and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a grain oriented silicon steel sheet, even in the case where a film containing no chromium is applied as a tension film, having high hygroscopic properties on a level same as that in the case where a chromium-containing film is formed.SOLUTION: Regarding the grain oriented silicon steel sheet in which the surface of a steel sheet is provided with a forsterite-based base film and a phosphate-based tension application film containing no chromium, the tension application film is formed by applying a phosphate-based coating treatment liquid containing no chromium to the surface of the forsterite-based base film containing Mn by 0.02 to 0.20 g/mexpressed in terms of weight and S by 0.01 to 0.10 g/mexpressed in terms of weight after final finish annealing and performing baking.

Description

  The present invention relates to a grain-oriented electrical steel sheet and a method for producing the same, and in particular, when a tension-imparting film not containing chromium is formed on the surface of a grain-oriented electrical steel sheet, unavoidably occurring coating defects are prevented and surface coating properties are improved. In addition to improving, it is intended to improve the iron loss by increasing the tension applied to the steel sheet.

In general, in a grain-oriented electrical steel sheet, for the purpose of reducing iron loss, a coating for imparting tension and imparting tension to the steel sheet is applied to the surface. These coatings are also required to have workability, rust prevention properties and the like. Such a surface film is usually composed of a base film mainly composed of forsterite formed at the time of final finish annealing and a phosphate-based topcoat film formed thereon.
These top coat films form a film having a low coefficient of thermal expansion at a high temperature, thereby applying tension to the steel sheet due to the difference in coefficient of thermal expansion between the steel sheet and the film when the temperature is lowered to room temperature.

Conventionally, various coating techniques have been proposed in order to impart the various characteristics as described above.
For example, Patent Document 1 has a coating mainly composed of magnesium phosphate, colloidal silica, and chromic anhydride, and Patent Document 2 has a coating mainly composed of aluminum phosphate, colloidal silica, and chromic anhydride. Each has been proposed.

On the other hand, in response to increasing interest in environmental conservation in recent years, there has been a growing demand for products that do not contain toxic substances such as chromium and lead, and the development of methods for forming coatings that do not contain chromium in grain-oriented electrical steels. Is desired.
However, if Cr-containing compounds such as chromic acid and chromate (hereinafter sometimes referred to simply as chromium and Cr) are not used, significant loss of hygroscopic resistance and loss of iron loss improvement effect due to reduced tension, etc. Due to quality problems, it was difficult to add no chromium. Here, the deterioration of moisture absorption resistance in the film means that the film absorbs moisture due to moisture in the atmosphere, and partially liquefies, resulting in a thin film thickness or a part without the film, That is, the insulation and rust prevention properties deteriorate.

As a method for solving the above problem, Patent Document 3 has developed a method of applying a coating liquid composed of colloidal silica and aluminum phosphate, boric acid and sulfate. By this method, the iron loss was improved and the moisture absorption resistance was improved by the tension imparting effect similar to that of the conventional chromium-containing coating.
However, the improvement of the iron loss and the moisture absorption resistance by this method has a problem that the effect varies and the iron loss and the moisture absorption resistance are deteriorated to a problem level in some cases.

As other coatings not containing chromium, for example, Patent Document 4 discloses a method in which a boric acid compound is added instead of a chromium compound, and Patent Document 5 discloses a method in which an oxide colloid is added. Discloses a method of adding a metal organic acid salt.
However, even when using any of the techniques, the effect of improving the moisture absorption resistance and the iron loss is greatly varied, and a complete solution has not been achieved.

Japanese Patent Publication No.56-52117 Japanese Patent Publication No.53-28375 Japanese Patent Publication No.57-9631 JP 2000-169973 A JP 2000-169972 A JP 2000-178760

  The present invention has been developed in view of the above circumstances, and even when a coating that does not contain chromium is applied as a tension coating, it has the same level of moisture absorption and low resistance as when a chromium-containing coating is formed. It is an object of the present invention to propose a grain-oriented electrical steel sheet that has achieved iron loss together with its advantageous manufacturing method.

Now, the inventors described in Patent Document 3 that the coating containing no chromium has a variation in moisture absorption resistance and iron loss improvement effect due to some disturbance factor and the desired characteristics cannot be achieved. Many experiments and examinations were repeated to investigate the cause.
As a result, it was found that good characteristics can be obtained by supplying Mn and S in the coating liquid and their compound ions from the undercoat to the coating.
The present invention is based on the above findings.

That is, the gist configuration of the present invention is as follows.
1. A grain-oriented electrical steel sheet having a forsterite-based undercoat and a chromium-based phosphate-based tension-imparting coating on the steel sheet surface,
The tension-imparting coating contains Mn 0.02 g / m ² or more and 0.20 g / m ² or less in terms of basis weight after final finish annealing, and S is 0.01 g / m ² or more and 0.10 g / m ² or less in terms of basis weight. A grain-oriented electrical steel sheet obtained by applying and baking a phosphate-based coating treatment liquid not containing chromium on the surface of a forsterite-based undercoat.

2. 2. The directionality according to 1 above, wherein the composition of the steel sheet is, by mass%, Si: 2.0% to 4.0% and Mn: 0.03 to 3.0%, the balance being Fe and inevitable impurities. Electrical steel sheet.

3. The steel sheet is further in terms of mass%: Ni: 0.03-1.50%, Sn: 0.01-1.50%, Sb: 0.005-1.50%, Cu: 0.03-3.0%, P: 0.03-0.50%, Mo: 0.005-0.10% Cr: 0.03-1.50%, Ti: 0.002-0.2%, B: 0.001-0.1%, Nb: 0.002-0.02%, Ge: 0.01-0.03%, Te: 0.002-0.05%, As: 0.002-0.05%, 3. The grain-oriented electrical steel sheet according to 2 above, containing at least one selected from Bi: 0.001 to 0.02% and V: 0.01 to 0.03%.

4). In mass%, C: 0.08% or less, Si: 2.0-4.0% and Mn: 0.03-3.0% are contained, Al is suppressed to 100ppm or less, N, S, and Se are suppressed to 50ppm or less respectively, and the balance is Fe and inevitable Steel slabs made of natural impurities are heated and then hot rolled, and after one or multiple cold rolling sandwiching intermediate annealing to the final sheet thickness, primary recrystallization annealing is performed, and then steel plate Manufacture of grain-oriented electrical steel sheets consisting of a series of steps in which an annealing separator containing magnesia as a main component is applied to the surface, followed by final finish annealing, and then forming a phosphate-based tension-imparting coating that does not contain chromium. In the method
One or two selected from the sulfate or sulfide of Mg, Ca, Sr, Ba, Na, K, Mn, Fe, Cu, Sn, Sb and Ni as the S-containing additive in the annealing separator By converting the above into SO ₃ amount and containing 1.5% or more and 20% or less in total, Mn is converted to 0.02g / m ² or more and 0.20g / in terms of basis weight in the forsterite undercoat after final finish annealing. m ^2, characterized in that is contained in the basis weight in terms 0.01 g / m ² or more 0.10 g / m ² or less S, the manufacturing method of the grain-oriented electrical steel sheet.

5. The steel slab is further in mass%, Ni: 0.03-1.50%, Sn: 0.01-1.50%, Sb: 0.005-1.50%, Cu: 0.03-3.0%, P: 0.03-0.50%, Mo: 0.005-0.10. %, Cr: 0.03-1.50%, Ti: 0.002-0.2%, B: 0.001-0.1%, Nb: 0.002-0.02%, Ge: 0.01-0.03%, Te: 0.002-0.05%, As: 0.002-0.05% Bi: 0.001 to 0.02% and V: 0.01 to 0.03%. The method for producing a grain-oriented electrical steel sheet according to 4 above, which contains at least one selected from 0.01 to 0.03%.

  ADVANTAGE OF THE INVENTION According to this invention, the grain-oriented electrical steel sheet which was excellent in both the magnetic characteristic and the film characteristic can be obtained stably using the top coat which does not contain chromium.

It is a figure which shows the relationship between the amount of Mn and S in a base film, and the magnetic characteristic after coating baking. It is a figure which shows the relationship between the amount of Mn and S in a base film, and the amount of P elution after coating baking. It is a figure which shows the relationship between the amount of Mn and S in a base film, and the rust generation rate after a coating baking.

Hereinafter, the present invention will be specifically described.
First, the experiment that led to the present invention will be described. Unless otherwise specified, “%” in relation to ingredients means mass%.
C: 0.045%, Si: 3.25%, and Mn: 0.07%, the remainder of the steel slab consisting of Fe and inevitable impurities was heated at 1180 ° C for 30 minutes, then hot rolled to a thickness of 2.2mm, then 950 ° C After hot-rolled sheet annealing for 1 minute, after finishing to a final sheet thickness of 0.23 mm by cold rolling with intermediate annealing at 1000 ° C. for 1 minute, atmospheric oxidation [P (H ₂ O) / P (H ₂ )] Decarburization annealing was performed at 850 ° C. for 2 minutes under the condition of 0.6. Thereafter, an annealing separator added with various proportions of magnesium oxide: 100 parts by mass, titanium oxide: 2 parts by mass and strontium sulfate was applied to the steel sheet surface on both sides at 12 g / m ² and dried. Secondary recrystallization annealing was performed, followed by purification annealing in dry H ₂ at 1200 ° C. for 10 hours, and then the unreacted separating agent was removed.

A part of the steel sheet thus obtained was collected, and Mn, S analysis of the steel sheet with film and the ground iron was performed, and thereby Mn, S in the film was calculated in terms of basis weight. Next, after phosphoric acid pickling, the composition of aluminum phosphate: 50 parts by mass, colloidal silica: 40 parts by mass, boric acid: 5 parts by mass, manganese sulfate: 10 parts by mass described in Patent Document 3 as a coating treatment liquid A coating solution (Cr-less) in a proportion was applied at a dry weight of 10 g / m ^{2 on} both sides, and then baked in a dry N ₂ atmosphere at 800 ° C. for 2 minutes. For comparison, a coating solution (containing Cr) composed of aluminum phosphate: 50 parts by mass, colloidal silica: 40 parts by mass, and chromic anhydride: 10 parts by mass was applied and baked in the same manner.

Magnetic measurement was performed on the steel sheet thus obtained.
Further, a dissolution test of P was also performed. In the P dissolution test, three 50 mm × 50 mm test pieces were immersed and boiled in 100 ° C. distilled water for 5 minutes to elute P from the coating surface and quantitatively analyze the P. The moisture absorption resistance can be evaluated by discriminating the easiness of dissolution of the coating film by the moisture content of P.
Further, as a corrosion resistance test, the rust generation rate (area ratio) of the steel sheet after a 50 mm × 100 mm test piece was exposed at a temperature of 50 ° C., a dew point of 50 ° C., and a time of 50 h was measured.

As for the investigation results thus obtained, the relationship between the magnetic properties, the P elution amount and the rust generation rate, and the Mn amount and S amount in the undercoat after finish annealing are arranged, and FIG. 1 (a), (b), 2 (a), 2 (b), 3 (a) and 3 (b), respectively. In addition, both the amount of Mn and the amount of S in the undercoat are shown in terms of basis weight per side.
As shown in FIGS. 3A and 3B, when a chromium-containing coating is used, the overall rust generation rate is low, and the rust generation rate is less dependent on the Mn basis weight and S basis weight.
In contrast, in the coating not containing chromium is high in rust incidence in many areas, Mn basis weight 0.02~0.20g / m ^2, S basis weight is good in the region of 0.01~0.10g / m ² Corrosion resistance is exhibited and corrosion resistance comparable to Cr-containing coatings is obtained.

The iron loss shown in FIGS. 1 (a) and 1 (b) and the P elution amount shown in FIGS. 2 (a) and 2 (b) are also shown in FIGS. 3 (a) and 3 (b). A similar tendency was obtained.
That is, even if the coating does not contain Cr, if the Mn basis weight satisfies the range of 0.02 to 0.20 g / m ² and the S basis weight satisfies the range of 0.01 to 0.10 g / m ² , it is equivalent to the coating containing Cr. Excellent iron loss improvement effect and P elution suppression effect were observed.

From the above results, the inventors considered the following effects of Mn and S basis weight on moisture absorption resistance, magnetic properties, and corrosion resistance in coatings not containing Cr.
First, when the phosphate coating does not contain Cr, part of the phosphoric acid is not formed as a network and is free, and it reacts with water, which tends to have poor moisture absorption and tension effects. It is in.
Here, when Cr is contained, the free phosphoric acid content in which the network is not formed is immobilized by the Cr-containing ions, thereby preventing moisture absorption and the accompanying decrease in the tension effect.

In the case of coatings that do not contain Cr, an inorganic compound that replaces Cr, which has the role of immobilizing phosphate ions, is often added, but manganese sulfate and other compounds that have been proposed so far Then the effect was not enough.
As a cause of this, the inventors agglomerated these compounds, resulting in locally concentrated and unconcentrated sites of these ions, and P elution occurred in the unconcentrated sites. Estimated.

  On the other hand, in the present invention, S penetrates into the steel from the additive in the annealing separator, and is combined with Mn to form MnS. Further, during the purification annealing, it moves to the base film and enters the base film. MnS is present. This MnS dissolves during coating baking and dissolves into the coating, but these ions can make the phosphate scavenging effect more effective.

Next, the reason why the composition of the steel slab, which is the steel plate and material of the present invention, is limited to the above range will be described.
First, the component composition of the steel sheet of the present invention will be described as follows.
Si: 2.0-4.0%
Si is an element effective in increasing the electrical resistance of steel and improving iron loss, but if the content is less than 2.0%, a sufficient iron loss reduction effect cannot be achieved, while if it exceeds 4.0% Since the workability is remarkably lowered and the magnetic flux density is also lowered, the Si content is set in the range of 2.0 to 4.0%.

Mn: 0.03-3.0%
In the present invention, Mn needs to be concentrated in the base film after finish annealing, and for this purpose at least 0.03% of Mn is required. Mn is an element useful for improving the hot workability, but if it exceeds 3.0%, the magnetic flux density of the product plate decreases, so the Mn content is in the range of 0.03 to 3.0%.

Further, in the present invention, in addition to the above-described components, the following elements can be appropriately contained as magnetic property improving components.
Ni: 0.03-1.50%, Sn: 0.01-1.50%, Sb: 0.005-1.50%, Cu: 0.03-3.0%, P: 0.03-0.50%, Mo: 0.005-0.10%, Cr: 0.03-1.50%, Ti : 0.002-0.2%, B: 0.001-0.1%, Nb: 0.002-0.02%, Ge: 0.01-0.03%, Te: 0.002-0.05%, As: 0.002-0.05%, Bi: 0.001-0.02% and V: At least one selected from 0.01 to 0.03%
Ni is an element useful for improving the magnetic properties by improving the hot-rolled sheet structure. However, if the content is less than 0.03%, the effect of improving the magnetic properties is small. On the other hand, if it exceeds 1.50%, secondary recrystallization becomes unstable and the magnetic properties deteriorate, so the Ni content is in the range of 0.03 to 1.50%. Is preferred.
Sn, Sb, Cu, P, Mo, Cr, Ti, B, Nb, Ge, Te, As, Bi, and V are elements useful for improving magnetic properties. If the lower limit is not satisfied, the effect of improving the magnetic properties is small. On the other hand, if the upper limit amount of each component described above is exceeded, the development of secondary recrystallized grains is hindered.
The balance other than the above components is inevitable impurities and Fe mixed in the manufacturing process.

Next, the component composition of the steel slab will be described as follows.
In addition, Si content and Mn content are the same as the component composition range prescribed | regulated about this invention steel plate.
The above-mentioned optional components are also the same as in the case of the steel sheet of the present invention.

C: 0.08% or less C is added to improve the hot-rolled sheet structure, but if it exceeds 0.08%, it is difficult to reduce C to 0.005% or less where magnetic aging does not occur during the manufacturing process. , 0.08% or less is preferable. In addition, regarding the lower limit, since a secondary recrystallization is possible even for a material not containing C, it is not particularly necessary to provide it.

Al: 100 ppm or less In the present invention, it is necessary to concentrate Mn and S in the base coating, but Al concentrates on the surface during finish annealing and prevents Mn and S from entering the coating. There is. Therefore, in order to suppress this, Al is preferably suppressed to 100 ppm or less.

N: 50 ppm or less In the present invention, since the Al content is suppressed to 100 ppm or less, the amount of N is also preferably reduced. This is because if N is high, there is surplus N that is not consumed as AlN, which causes blistering during slab heating. Therefore, it is preferable to suppress N to 50 ppm or less.

S: 50 ppm or less In the present invention, a large amount of S compound is added to the annealing separator to concentrate S on the surface after finish annealing, so S in steel is not particularly necessary. Further, excessive addition of S causes incomplete solid solution during slab heating, leading to deterioration of magnetic properties. Therefore, S is preferably 50 ppm or less.

Se: 50 ppm or less Se, like S, excessive addition of Se causes incomplete solid solution during slab heating, leading to deterioration of magnetic properties. Therefore, Se is preferably 50 ppm or less.

Next, the manufacturing method of this invention is demonstrated.
The steel slab adjusted to the above preferred component composition is hot-rolled by a known method, finished to the final sheet thickness by one or multiple cold rolling sandwiching intermediate annealing, and then subjected to primary recrystallization annealing, Next, a final finish annealing is performed after an annealing separator is applied to the surface of the steel sheet. At this time, in order to form a forsterite film as a base film, 50% or more of magnesia (MgO) is used as a main component of the annealing separator. Unless otherwise specified, when expressed as a percentage by the component ratio of the annealing separator and the top coat, it is mass%.
And in order to make S exist in an undercoat, what is necessary is just to add S source to an annealing separation agent. The form of the S source is not particularly limited, but one or two selected from sulfates or sulfides of Mg, Ca, Sr, Ba, Na, K, Mn, Fe, Cu, Sn, Sb, and Ni. It is sufficient to contain more than 1.5% of the seeds in terms of SO ₃ amount and not more than 1.5% and not more than 20%. Thereby, S is combined with Mn in the steel during the finish annealing to become MnS, and further moves to the surface during the purification annealing and can be concentrated in the undercoat. If the content of these sulfates or sulfides is less than 1.5% in total in terms of SO ₃ amount, it is difficult to secure a predetermined amount of S per unit area in the undercoat, and SO ₃ If the total amount exceeds 20% in terms of amount, Mn and S may be excessively concentrated in the undercoat, so 1.5 to 20% is preferable.

  In addition to this, known annealing separator additives such as oxides, hydroxides and carbonates of Ti, Sn, Mg, Sr, Na, K, Mn, Fe, Cu, Sn, Sb, etc. One kind or two or more kinds can also be used.

Mn is 0.02g / m ² or more and 0.20g / m ² or less in terms of basis weight, and S is 0.01g in terms of basis weight in the forsterite-based undercoating of the directionally annealed grain-oriented electrical steel sheet thus manufactured. / m ² or more and 0.10 g / m ² or less. If the Mn basis weight or the S basis weight is lower than the lower limit value, the moisture absorption resistance is inferior. On the other hand, if the Mn basis weight is lower than the upper limit value, the amount of liberation from the base coat increases so much that the base coat is damaged, resulting in magnetic properties and film adhesion. Deteriorates.

  Next, a phosphate-based coating solution not containing chromium is applied to the surface of the obtained steel plate. As a coating component, a conventionally known one, for example, a coating solution composed of colloidal silica and aluminum phosphate described in Patent Document 3, boric acid and sulfate, a method of adding a boric acid compound described in Patent Document 4, Any of the method of adding the oxide colloid described in Patent Document 5 and the method of adding the metal organic acid salt described in Patent Document 6 can be used. Further, it is possible to improve the sticking resistance by adding inorganic mineral particles such as silica and alumina to these.

The basis weight of the phosphate-based tension applying coating is desirably 4 to 15 g / m ^{2 on} both sides. Less the interlayer resistance than 4g / m ² is reduced, because the larger the space factor than 15 g / m ² is reduced.
After this coating is applied and dried, it is flattened and annealed for baking. The conditions for the flattening annealing are not particularly limited, but the annealing temperature is desirably a soaking time of about 2 to 120 seconds in a temperature range of 700 to 950 ° C. If the temperature is too low or the time is too short, the flattening will be insufficient and the yield will decrease due to the shape defect.On the other hand, if the temperature is too high or the time is too long, the effect of flattening annealing will be too strong and creep deformation will occur. It occurs and the magnetic properties deteriorate.

Example 1
C: 0.05%, Si: 3.2%, Mn: 0.05% and Sb: 0.02%, steel slab consisting of Fe and unavoidable impurities in the balance is heated at 1180 ° C for 30 minutes and hot-rolled to a thickness of 2.2 mm Then, after hot-rolled sheet annealing at 950 ° C. for 1 minute, after finishing to a final sheet thickness of 0.30 mm by cold rolling, atmospheric oxidation [P (H ₂ O) / P (H ₂ )] = 0.5 Under conditions, decarburization annealing was performed at 850 ° C. for 2 minutes. Thereafter, an annealing separator containing 2 parts by mass of titanium oxide and various proportions of strontium sulfate with respect to 100 parts by mass of magnesium oxide on the steel sheet surface was coated on the steel sheet surface at 12 g / m ² on both sides and dried. Thereafter, secondary recrystallization annealing was performed, followed by purification annealing in dry H ₂ at 1200 ° C. for 10 hours, and then the unreacted separating agent was removed.

The steel plate thus obtained was sheared to a size of 300 mm × 100 mm and subjected to magnetic measurement with an SST (Single Sheet Tester). Incidentally, the magnetic flux density of the steel sheet after finish annealing was both at B ₈ 1.90 (T).
Further, a part of the steel plate was sampled and subjected to Mn, S analysis of the steel plate with film and the ground iron, and thereby Mn, S in the membrane was calculated in basis weight conversion (per both sides).
Next, after phosphoric acid pickling, the coating composition on both sides is such that the component composition is in the ratio of dry solids, colloidal silica: 50%, magnesium phosphate: 40%, manganese sulfate: 9.5%, fine powder silica particles: 0.5% After applying 10 g / m ^2, it was baked at 850 ° C. for 30 seconds in a dry N ₂ atmosphere.
Table 1 shows the results of investigation of various properties of the steel sheet thus obtained.

In addition, the evaluation method of each characteristic is as follows.
Flourability The steel plate surface was observed with a scanning electron microscope and evaluated as follows.
○: No swelling or cracking on the surface △: Slight swelling or cracking on the surface ×: Significant swelling or cracking on the surface

Heat-resistant
Ten test pieces of 50 mm x 50 mm were laminated, annealed at 800 ° C for 2 hours under a compressive load of ² kg / mm ² in a dry nitrogen atmosphere, and then a 500 g weight was dropped on the surface of the test piece. Based on the drop height when all of the films were peeled off, it was determined as follows.
○: 20cm
Δ: 40cm
×: More than 60cm

The magnetostriction λ _PP was evaluated by a compressive stress value (kg / mm ² ) at 4 × 10 ⁻⁴ .

Adhesion
A test piece of 300 mm × 30 mm was bent 180 ° while being pressed against a round bar having various diameters, and the minimum diameter (mm) at which the bent portion was not peeled was evaluated.

Space factor
Measurement was performed in accordance with the method described in JIS C 2550 (2000).

Rust prevention property The surface after being kept in air at a temperature of 50 ° C. and a dew point of 50 ° C. for 50 hours was determined as follows.
○: almost no rust (0 to 5%)
Δ: Some rust was generated (over 5% to 20%)
×: Remarkably rusted (over 20%)

  As shown in the table, according to the present invention, when an appropriate amount of strontium sulfate is added to the annealing separator, and the Mn basis weight and S basis weight in the undercoat are controlled within an appropriate range, both are good. Surface characteristics and iron loss characteristics are obtained.

Example 2
The steel plate that was subjected to decarburization annealing in the same manner as in Example 1 was subjected to two conditions of 0.7% and 8% in terms of MgO, 2% TiO ₂ and magnesium sulfate in terms of SO ₃ as the annealing separator. The added annealing separator was applied, and after finishing annealing in the same manner as in Example 1, the unreacted separating agent was removed. Next, after phosphoric acid pickling, the component composition is in the ratio of dry solids, colloidal silica: 50%, various primary phosphate compounds: 40%, various inorganic compounds (Cr substitutes): 9.5% and fine powder silica Particles: A coating of 0.5% was applied on both sides at 10 g / m ² , followed by baking at 850 ° C. for 30 seconds in a dry N ₂ atmosphere.
Table 2 shows the results of investigating various properties of the steel sheet thus obtained.

  As shown in the table, according to the present invention, even when a phosphate-based film not containing chromium is used as the tension-imparting film, good surface characteristics and iron loss characteristics can be obtained together. Yes.

Example 3
A steel slab having the component composition shown in Table 3 was subjected to final finish annealing in the same manner as in Example 1, and then the unreacted separating agent was removed, followed by phosphoric acid pickling. Next, after applying 10 g / m ^{2 of} coating on both sides of colloidal silica: 50%, magnesium phosphate: 40%, iron sulfate: 10%, the temperature was increased from 200 to 700 ° C. at a rate of 20 ° C./s. After that, it was baked at 850 ° C. for 30 seconds in a dry N ₂ atmosphere.
Table 4 shows the results of investigating various properties of the steel sheet thus obtained.

同表から明らかなように、本発明によれば、各種の抑制力補強元素を添加した場合でも、良好な表面特性と鉄損特性が得られている。

As is apparent from the table, according to the present invention, even when various restraining force reinforcing elements are added, good surface characteristics and iron loss characteristics are obtained.

Example 4
After applying to the steel sheet that had been decarburized and annealed in the same manner as in Example 1, an annealing separator containing 2% TiO ₂ and various chemicals added in various proportions to MgO as an annealing separator, Example 1 and Finish annealing was performed in the same manner. Then, after phosphorus Sansan'arai, colloidal silica: 50%, magnesium phosphate: 40%, iron sulfate: After subjecting 10 g / m ² to 10% become coated on both sides, 20 ° C. / s up to 200 to 700 ° C. After the temperature was raised at a rate of 850 ° C., a baking treatment was performed at 850 ° C. for 30 seconds in a dry N ₂ atmosphere.
Table 5 shows the results of investigation of various properties of the steel sheet thus obtained.

  As shown in the table, according to the present invention, good surface characteristics and iron loss characteristics are obtained even when various chemicals are added to the separating agent.

Claims (5)

A grain-oriented electrical steel sheet having a forsterite-based undercoat and a chromium-based phosphate-based tension-imparting coating on the steel sheet surface,
The tension-imparting coating contains Mn 0.02 g / m ² or more and 0.20 g / m ² or less in terms of basis weight after final finish annealing, and S is 0.01 g / m ² or more and 0.10 g / m ² or less in terms of basis weight. A grain-oriented electrical steel sheet obtained by applying and baking a phosphate-based coating treatment liquid not containing chromium on the surface of a forsterite-based undercoat.   2. The direction according to claim 1, wherein the composition of the steel sheet is, by mass%, Si: 2.0% to 4.0% and Mn: 0.03 to 3.0%, with the balance being Fe and inevitable impurities. Electrical steel sheet.   The steel sheet is further in terms of mass%: Ni: 0.03-1.50%, Sn: 0.01-1.50%, Sb: 0.005-1.50%, Cu: 0.03-3.0%, P: 0.03-0.50%, Mo: 0.005-0.10% Cr: 0.03-1.50%, Ti: 0.002-0.2%, B: 0.001-0.1%, Nb: 0.002-0.02%, Ge: 0.01-0.03%, Te: 0.002-0.05%, As: 0.002-0.05%, The grain-oriented electrical steel sheet according to claim 2, containing at least one selected from Bi: 0.001 to 0.02% and V: 0.01 to 0.03%. In mass%, C: 0.08% or less, Si: 2.0-4.0% and Mn: 0.03-3.0% are contained, Al is suppressed to 100ppm or less, N, S, and Se are suppressed to 50ppm or less respectively, and the balance is Fe and inevitable Steel slabs made of natural impurities are heated and then hot rolled, and after one or multiple cold rolling sandwiching intermediate annealing to the final sheet thickness, primary recrystallization annealing is performed, and then steel plate Manufacture of grain-oriented electrical steel sheets consisting of a series of steps in which an annealing separator containing magnesia as a main component is applied to the surface, followed by final finish annealing, and then forming a phosphate-based tension-imparting coating that does not contain chromium. In the method
One or two selected from the sulfate or sulfide of Mg, Ca, Sr, Ba, Na, K, Mn, Fe, Cu, Sn, Sb and Ni as the S-containing additive in the annealing separator By converting the above into SO ₃ amount and containing 1.5% or more and 20% or less in total, Mn is converted to 0.02g / m ² or more and 0.20g / in terms of basis weight in the forsterite undercoat after final finish annealing. m ^2, characterized in that is contained in the basis weight in terms 0.01 g / m ² or more 0.10 g / m ² or less S, the manufacturing method of the grain-oriented electrical steel sheet.   The steel slab is further in mass%, Ni: 0.03-1.50%, Sn: 0.01-1.50%, Sb: 0.005-1.50%, Cu: 0.03-3.0%, P: 0.03-0.50%, Mo: 0.005-0.10. %, Cr: 0.03-1.50%, Ti: 0.002-0.2%, B: 0.001-0.1%, Nb: 0.002-0.02%, Ge: 0.01-0.03%, Te: 0.002-0.05%, As: 0.002-0.05% 5. The method for producing a grain-oriented electrical steel sheet according to claim 4, comprising at least one selected from Bi: 0.001 to 0.02% and V: 0.01 to 0.03%.

Images