JPH0322449B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) Regarding the manufacturing method of grain-oriented silicon steel sheets, this specification specifically describes development results related to improving iron loss characteristics without reducing magnetic flux density. The characteristics required of grain-oriented silicon steel sheets are high magnetic flux density and low iron loss. Conventional methods to reduce iron loss include reducing the product thickness to increase the Si content, reducing impurities, increasing the degree of integration of secondary recrystallized grains in the (110)[001] orientation, that is, the Goss orientation. Although methods such as reducing the size of secondary recrystallized grains are known, the present invention also relates to a method of advantageously increasing the degree of Goss orientation integration of secondary recrystallized grains. (Prior art) The final strong cold rolling method for Al-containing materials as described in Japanese Patent Publication No. 40-15644,
Although the degree of Goss orientation accumulation of secondary recrystallized grains is certainly increased by the low-temperature holding secondary recrystallization method for Sb-containing materials as disclosed in Publication No. 51-13469, on the other hand, the secondary recrystallization The problem remains that the coarsening of recrystallized grains is unavoidable, and as a result, the iron loss of the product deteriorates. (Problems to be Solved by the Invention) In view of the above circumstances, overcoming the above-mentioned drawbacks of the conventional technology in the production of unidirectional silicon steel sheets,
To obtain a unidirectional silicon steel sheet with always stable and excellent magnetic properties by increasing the degree of Goss orientation integration of secondary recrystallized grains and reducing the core loss of the product by making the crystal grains smaller instead of increasing them. It is an object of the present invention to propose a manufacturing method that enables the following. (Means for Solving the Problems) As a result of intensive research to solve the above problems, the inventors discovered that in the manufacturing process of grain-oriented silicon steel sheets, after the final cold rolling and prior to decarburization annealing, It has been found that attaching Zn, P, or a substance containing them to the surface of a steel sheet is extremely effective in achieving the intended purpose. This invention is derived from the above knowledge. The present invention provides, as a primary recrystallized grain growth inhibitor,
A hot rolled silicon steel sheet containing at least one of S, Se and Te is cold rolled at least once, then decarburized annealed, and then an annealing separator is applied to the surface of the steel sheet. In manufacturing unidirectional silicon steel sheets by final annealing after final cold rolling, Zn, ZnO,
ZnSO ₄ 7H ₂ O and ZnS and P, P ₂ O ₅ ,
H ₃ PO ₄ , PCl ₅ , H ₃ PO ₃ , NaH ₂ PO ₄・2H ₂ O and
This is a method for producing a unidirectional silicon steel sheet, characterized in that a substance consisting of at least one selected from Na ₄ P ₂ O ₇ is uniformly adhered to the surface of the steel sheet. In this invention, the basis weight of at least one selected from the above-mentioned Zn and Zn-containing substances and P and P-containing substances is 2 μg/m in terms of Zn and/or P and in total on both sides of the steel plate. A value of ² or more is particularly advantageously suited. Among these substances, those that are soluble in water are applied to the surface of the steel sheet as an aqueous solution, while those that are sparingly soluble or insoluble, such as ZnO, are used as a suspension.
When using ZnO here, 1μ on the steel plate surface
It is advantageous to have a particle size distribution in which at least 50% of the particles have a particle size of m or less. The present invention will be specifically explained below based on the experimental results that led to this invention. A 2.0 mm thick hot-rolled sheet containing Si: 3.2%, Mn: 0.06%, Se: 0.026% and Sb: 0.048% was annealed at 1000°C for 1 min, and then intermediately annealed at 95°C for 2 min. After finishing to a thickness of 0.23 mm by two-time cold rolling method and degreasing, the cold rolled sheet was immersed in a ZnSO ₄ 7H ₂ O aqueous solution, and then decarburized for 3 minutes in wet hydrogen at 830°C. After annealing, an annealing separator mainly composed of MgO was applied, and final annealing was performed at 1200°C for 5 hours in an H ₂ atmosphere. During the immersion treatment in the above ZnSO ₄ .7H ₂ O aqueous solution, the concentration, solution temperature, and treatment time were adjusted to vary the amount of Zn deposited on the steel plate surface. In addition, in the final annealing, the secondary recrystallized structure was sufficiently developed in the range of 850 to 900°C. Figure 1 shows the results of examining the magnetic properties and particle size of the obtained product. As is clear from the figure, if an appropriate basis weight, especially Zn, of 2 μg/m ² or more is applied to the steel plate, the grain size of the product will decrease, the magnetic flux density _B10 will increase, and the iron loss W17/50 will also increase. significantly reduced. Next, a 2.0 mm thick hot-rolled plate containing Si: 3.35%, Mn: 0.067%, S: 0.027% and Te: 0.007% was annealed at 1000°C for 1 min, and then heated at 950°C.
0.20 by double cold rolling method with 2 min intermediate annealing.
After finishing to a thickness of mm and degreasing, the cold-rolled plate was immersed in an aqueous H ₃ PO ₄ solution, then subjected to decarburization annealing for 3 minutes in wet hydrogen at 830°C, and then coated with an annealing separation agent mainly composed of MgO. then 1200 in _H2 atmosphere
Finish annealing was performed at ℃ for 5 hours. During the immersion treatment in the H ₃ PO ₄ aqueous solution described above, the concentration, solution temperature, and treatment time were adjusted to vary the amount of P deposited on the steel plate surface. In addition, in the final annealing, the secondary recrystallized structure was sufficiently developed in the range of 850 to 900%. Figure 2 shows the results of examining the particle size and magnetic properties of the obtained product. As is clear from the figure, when an appropriate amount of basis weight, especially P of 2 μg/m ² or more is applied to a steel plate, the particle size of the product decreases, the magnetic flux density _B10 improves, and the iron loss W17 /50 was also significantly reduced. Next, Si: 3.35%, Mn: 0.081%, S: 0.024%,
A 2.5 mm thick hot-rolled sheet with a composition containing 0.026% Se was annealed at 980°C for 1 minute and then finished to 0.27 mm by a two-time cold rolling process with intermediate annealing at 1000°C for 1 minute. After degreasing, the cold-rolled sheet was immersed in a ZnO suspension to adjust the adhesion amount on both sides of the steel sheet to a range of 5 to 10 mg/m ² . After that, decarburization annealing was performed for 2.5 min in humid hydrogen at 825°C, and then an annealing separator mainly composed of MgO was applied, and then annealing was performed at 1200°C for 5 h in an _H2 atmosphere.
Finish annealing was performed. In the surface particle size distribution when the ZnO suspension described above is applied to the surface of a steel plate, the ratio of 1 μm or less is reduced to 0.
~100%. Figure 3 shows the results of investigating the magnetic properties of the obtained product. As is clear from the figure, the proportion of 1 μm or less is 50
It was found that the iron loss value W17/50 decreased significantly in the region of % or more. The manufacturing method according to the present invention will be explained below in order of steps. First of all, regarding the composition of the material, Si: 2.5 to 4.0
%, C: 0.02-0.08% and Mn: 0.01-0.20%, as well as at least one selected from S, Se and Te, S: 0.005-0.05%, Se: 0.005
It is desirable to add Te in the range of ~0.05% and Te: 0.003 to 0.05%. Furthermore, it is suitable to further increase the suppressing power by adding at least one of Al or B and N to the above components, and acid-soluble Al: 0.01 to
0.065%, B: 0.0005-0.0045% and N: 0.002
It is desirable to add in the range of ~0.010%. Si is used to obtain a sufficiently low iron loss without significantly impairing the cold rolling yield, C is used to refine the grains after hot rolling, and other ingredients are used as primary recrystallization grain growth inhibitors. In order to have an effective effect, it is preferable to add each of them within the above-mentioned ranges, but even if they are added outside this range, a certain degree of effect can be obtained. Now, there are no special restrictions on the steelmaking and hot rolling processes.
A generally known method may be applied. Intermediate annealing in the hot-rolled plate annealing and cold rolling process is performed at a temperature of 750 to 1100℃ for 10 seconds or more as necessary.
Just apply it for 10 minutes. After that, the thickness of the product is determined by cold rolling one or more times, and after degreasing by a known method, Zn
Alternatively, at least one selected from Zn-containing substances and P or P-containing substances is uniformly adhered to the surface of the steel sheet. Methods for this include dipping,
All methods such as spraying, coating, electrodeposition, dropping, and transfer can be used. Thereafter, decarburization annealing is performed in a hydrogen atmosphere containing water vapor at 700 to 900°C until the C content in the steel is approximately 0.005% or less. Then, after applying an annealing separator mainly composed of MgO, secondary recrystallization annealing is performed at a temperature range of 800 to 1000℃.
Subsequently, purification annealing is performed in a hydrogen atmosphere at a temperature range of 1100 to 1250°C. After removing the separating agent, a tension coating is applied, and then flattening annealing is performed at a temperature range of 700 to 900°C. (Function) The reason why magnetic properties are improved by uniformly attaching Zn, P, or substances containing these to the surface of a cold rolled steel sheet after final cold rolling and prior to decarburization annealing according to the present invention is as follows. Although it has not yet been clearly elucidated, if such a substance is attached to the surface of a steel sheet, it not only refines the secondary recrystallized grains in the subsequent secondary recrystallization annealing, but also improves the Goss orientation. It is thought that the degree of integration increases, resulting in a reduction in iron loss and an improvement in magnetic flux density. It should be noted that improvement of the magnetic properties can be achieved with a small amount of the above substance in terms of Zn or/and P, and the total amount on both sides of the steel plate is about 2μg/ ^m2 or more, and such treatment does not necessarily apply to both sides. It is not necessary to apply it, and it is effective even if it is applied only to one side, but even in this case, in order to obtain good magnetic properties, it is desirable that the area weight is 2 μg/m ² or more. Also, some of these substances are water-soluble and others are poorly soluble or insoluble; for example, ZnO
For poorly soluble materials, it is important to sufficiently suspend them in the liquid by stirring or circulating them in the liquid, and to create a particle size distribution in which at least 50% of the particles are 1 μm or less on the surface of the steel plate. Therefore, the above-mentioned poorly soluble or insoluble substances need to be sufficiently pulverized to form fine particles. (Example) Example 1 C: 0.04%, Si: 3.35%, Mn: 0.068%, Se:
The composition contains 0.022% and Sb: 0.029%.
After annealing a 2.0mm thick hot rolled plate at 1000℃ for 1min,
A cold-rolled sheet that was first cold-rolled to 0.60 mm, intermediately annealed at 950°C for 1 mm, and finished to a final thickness of 0.23 mm was immersed for 9 seconds in an aqueous solution at 30°C containing 0.002 mol/ZnS. , after passing it through a rubber squeezing roll.
Dry in an air bath at 150°C. At this point, the amount of Zn deposited was 5.8 mg/m ² . Next, decarburization annealing was performed at 825°C for 3 minutes in an atmosphere consisting of 50% H ₂ and balance N ₂ with a dew point of 60°C.
Apply MgO slurry and then in _N2 atmosphere
A final annealing was performed at 870°C for 30h, followed by a final annealing at 1200°C for 10h in an _H2 atmosphere. Table 1 shows the results of investigating the magnetic properties and particle size of the obtained product, comparing it with a conventional product that did not go through the ZnS coating process.

[Table] Application of Zn-containing material before decarburization annealing results in finer grains and significant reduction in iron loss, B ₁₀
Improvements in value have been achieved. Example 2 C: 0.051%, Si: 3.33%, Mn: 0.069%, Se:
After annealing a 2 mm thick hot rolled plate containing 0.027% and Te: 0.007% at 1000°C for 1 min,
First cold rolled to 0.60mm, intermediate annealed at 950℃ for 1 minute, then secondly cold rolled to a final thickness of 0.20mm.
The degreased cold-rolled sheet was then immersed in a 45°C aqueous solution containing 0.0015 mol of P ₂ O ₅ for 6 seconds, passed through a rubber squeezing roll, and then passed through a rubber squeezing roll.
Dry in an air bath at 200°C. At this point, the amount of P deposited was 3.9 mg/m ² . Next, decarburization annealing was performed at 835°C for 3 minutes in an atmosphere consisting of 50% H ₂ and balance N ₂ with a dew point of 60°C.
870 in _N2 atmosphere after applying MgO slurry
°C for 25 h, followed by final annealing at 1200 °C for 10 h in an _H2 atmosphere. Table 2 shows the results of an investigation of the magnetic properties and particle size of the obtained product in comparison with a conventional product that was not subjected to P ₂ O ₅ coating treatment.

[Table] By applying a P-containing substance before decarburization annealing, it was possible to refine the product grains, significantly reduce iron loss, and improve the _B10 value. Example 3 C: 0.048%, Si: 3.28%, Mn: 0.088%, S:
The composition contains 0.025% and Te: 0.008%.
After annealing a 2.5mm thick hot rolled plate at 900℃ for 8min.
First cold rolled to a thickness of 0.70mm, intermediate annealed at 950℃ for 3 minutes, then second cold rolled to a final thickness of 0.27mm.
A degreased cold-rolled sheet was immersed in a suspension containing 0.015 mol of ZnO at 20°C for 18 seconds, passed through a rubber squeeze roll, and then heated to 180°C.
dried in an air bath. At this point, the ZnO particle size distribution of 1 μm or less on the surface of the steel plate was 87%, and the amount of Zn deposited was 15.5 mg/m ² . Then in an atmosphere consisting of 50% _H2 and balance _N2 .
After decarburizing annealing at 830℃ for 3 minutes, MgO slurry was applied and dried, then heated at 865℃ for 30 hours in a _N2 atmosphere.
Then, final annealing was performed at 1200° C. for 10 hours in an H ₂ atmosphere. The results of an investigation of the magnetic properties and particle size of the obtained product are shown in Table 3 in comparison with conventional products, and the effects of this invention are clearly evident.

[Table] Example 4 C: 0.057%, Si: 3.20%, Mn: 0.085%, S:
A 2.4 mm thick hot rolled sheet containing 0.028%, Sol, Al: 0.021%, and N: 0.0065% is made into a 1.60 mm thick sheet.
The cold-rolled sheet was then cold-rolled, intermediately annealed at 1050℃ for 1 min, and then cold-rolled to a final thickness of _0.23 mm, and _degreased . The specimen was immersed in an aqueous solution at 25°C for 6 seconds, passed through a rubber squeezing roll, and dried in an air bath at 180°C. At this point, the amount of Zn deposited was 18 mg/m ² . Then, decarburization annealing was performed at 835°C for 3 minutes in an atmosphere consisting of H ₂ 50% balance N ₂ with a dew point of 60°C.
850 in _H2 atmosphere after applying MgO slurry
℃ for 50 hours, and then the magnetic properties and particle size of the obtained product were investigated, and Table 4 shows a comparison with a conventional product that was not subjected to the ZnSO ₄ 7H ₂ O coating treatment.

[Table] By attaching Zn to the surface of the steel sheet prior to decarburization annealing, the grain size of the product was reduced, the magnetic flux density was improved, and the iron loss was significantly reduced. Example 5 C: 0.030%, Si: 3.15%, Mn: 0.025%, S:
0.003%, Se: 0.015%, B: 0.008%, N: 0.0045
1000℃, 1min on a 1.8mm thick hot-rolled plate containing
After annealing, it was cold rolled once to a final thickness of 0.23 mm. After degreasing this cold-rolled sheet, it was immersed in an aqueous solution at 45°C containing 0.0015 mol of P ₂ O ₅ for 6 seconds, passed through a rubber squeezing roll, and then
Dry in an air bath at 200°C. At this point, the amount of P attached was 4.1 mg/m ² . Then decarburization annealing was performed at 830°C for 3 min in an atmosphere consisting of H ₂ 50% balance N ₂ with a dew point of 60°C, and the MgO
After the slurry was applied and dried, final annealing was performed at 1200°C for 10 hours in hydrogen. Table 5 shows the results of investigating the magnetic properties and particle size of the obtained product in comparison with conventional products.

[Table] Significant grain refinement and improvement in magnetic properties were observed by applying a P-containing substance prior to decarburization annealing. Example 6 C: 0.045%, Si: 3.05%, Mn: 0.031%, S:
0.002%, Te: 0.007%, B: 0.0012%, N:
A 2.5mm thick hot rolled plate containing 0.0036% is cold rolled,
It was first cold rolled to 1.1 mm, intermediately annealed at 1000°C for 1 minute, and then finished to a final thickness of 0.20 mm by second cold rolling. After degreasing this cold-rolled sheet, ZnS
A 30°C aqueous solution containing 0.001 mol of was applied by spraying, and 5 seconds later, it was passed through a rubber squeezing roll and dried. At this point, the amount of Zn deposited was 10.7 mg/m ² . Next, decarburization annealing was performed at 830°C for 3 minutes in wet hydrogen, and after coating and drying MgO slurry, final annealing was performed at 850°C for 50 hours and then at 1200°C for 10 hours in an H ₂ atmosphere. Table 6 shows the results of investigating the magnetic properties and particle size of the obtained product in comparison with conventional products.

[Table] By applying a Zn-containing material prior to decarburization annealing, significant improvements in not only magnetic flux density but also iron loss characteristics were achieved. Example 7 C: 0.030%, Si: 3.25%, Mn: 0.078%, Se:
0.025%, S: 0.003% and P: 0.004%, with the remainder being essentially Fe. After annealing at 1000°C for 2 minutes,
Finished with one cold rolling to a final thickness of mm. After degreasing this cold-rolled sheet, various chemicals shown in Table 7 were applied to a part of the cold-rolled part and dried in an air bath at 200°C. The amounts of Zn and P deposited at this time were as shown in Table 7. Next, decarburization annealing was performed at 840°C for 2 min in an atmosphere of 60°C dew point and 50% H ₂ with the balance being N ₂ , MgO slurry was applied and dried, and then annealing was performed at 1160°C in dry hydrogen for 10 min.
Finish annealing was performed for an hour. The results of the investigation on the magnetic properties and particle size of the thus obtained product are also listed in Table 7 in comparison with those of the conventional product.

[Table] As is clear from the table, prior to decarburization annealing,
By coating Zn, P, or a substance containing them, significant grain refinement and improvement in magnetic properties have been achieved. (Effects of the Invention) Thus, according to the present invention, it is possible to effectively refine the grain size of a unidirectional silicon steel sheet and achieve a remarkable improvement in iron loss characteristics as well as an increase in magnetic flux density. .

[Brief explanation of drawings]

Figure 1 shows Zn on the surface of the steel sheet after decarburization annealing.
Figure 2 is a graph showing the relationship between the amount of P adhesion, magnetic flux density, iron loss value, and product particle size, and also shows the relationship between the amount of P adhesion, magnetic flux density, iron loss value, and product particle size after decarburization annealing. FIG. 3 is a graph showing the relationship between the ZnO particle size distribution ratio of 1 μm or less on the steel plate surface and the iron loss value.

Claims (1)

[Claims] 1. A silicon steel hot rolled sheet containing at least one of S, Se and Te as a primary recrystallized grain growth inhibitor is cold rolled at least once, and then In producing a grain-oriented silicon steel sheet by performing decarburization annealing, then applying an annealing separator to the surface of the steel sheet, and then performing final annealing, after the final cold rolling and prior to the decarburization annealing, Zn, ZnO,
ZnSO ₄ 7H ₂ O and ZnS and P, P ₂ O ₅ ,
H ₃ PO ₄ , PCl ₅ , H ₃ PO ₃ , NaH ₂ PO ₄・2H ₂ O and
A method for producing a unidirectional silicon steel sheet, characterized in that a substance consisting of at least one selected from Na ₄ P ₂ O ₇ is uniformly adhered to the surface of the steel sheet. 2 Zn, ZnO, ZnSO ₄・7H ₂ O and ZnS and P,
P ₂ O ₅ , H ₃ PO ₄ , PCl ₅ , H ₃ PO ₃ , NaH ₂ PO ₄・
Claim 1, wherein the basis weight of at least one selected from 2H ₂ O and Na ₄ P ₂ O ₇ is 2 μg/m ² or more in terms of Zn and/or P in total on both sides of the steel plate. The method described in section. 3. The method according to claim 1, wherein the deposited substance is ZnO and the grain size distribution on the surface of the steel plate is such that the grain size of 1 μm or less is 50% or more.