JPH0734128A - Production of electrical steel sheet for static machine having excellent magnetic characteristics in two directions - Google Patents

Abstract

PURPOSE:To provide a process for production of the bidirectional electrical steel sheet having extremely outstanding magnetic characteristics by regulating the texture and cold rolling rate of a slab in production of the electrical steel strip by using a steel strip obtd. by solidification of molten steel by a moving and refreshing surface of a cooling body. CONSTITUTION:The {100} face strength parallel with the front surface of the billet in the central layer at the thickness of the billet in the case of formation of the steel strip is specified to 2.3 times in paired random and the rolling rate at the time of cold rolling to >=15 and <50% in the production of the electrical steel sheet by solidifying the molten steel consisting of <=4.0% Si, <=2.0% Al and >2.5% (Si+2Al) and the balance substantially Fe by the moving and refreshing surface of the cooling body to form the cast steel strip, then cold rolling the cast steel strip to a prescribed thickness then subjecting the steel strip to finish annealing. As a result, the main bearings attain {100}, <011> after the finish annealing. The electrical steel sheet suitable for static apparatus is obtd. The characteristics (efficiency) of the apparatus are greatly improved even when the electrical steel sheet is used for a rotating machine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetic steel sheet for a stationary machine, which has extremely high magnetic flux density in two specific directions and low iron loss.

[0002]

2. Description of the Related Art Recently, not only magnetic core materials for rotating machines but also
From the viewpoint of energy saving and noise, the demand for improving the quality of magnetic steel sheets as a magnetic core material for stationary machines is increasing more and more. In order to meet this demand, electromagnetic steel sheet manufacturers are also conducting research and development to improve the magnetic properties of the electromagnetic steel sheets. In the manufacturing process of electrical steel sheets using primary recrystallization, in order to obtain a product with a low iron loss value, conventionally, the steel is highly purified in its melting stage, the Si content in the steel is increased, and the finishing is performed. Magnetic steel sheets with less directivity are manufactured by means such as taking sufficient temperature and time in annealing. However, when these technical means are used, they are so-called non-directional and are not suitable for stationary machines.

In order to solve this problem, so-called unidirectional electrical steel sheet may be used. In this case, the product texture is so-called Goss and the unidirectional (rolling direction) magnetism is extremely good. However, the magnetism in other directions is inferior. Furthermore, it is very expensive because it utilizes secondary recrystallization. Recently, a method has been developed to obtain a non-oriented electrical steel sheet which is solidified by a moving and renewing cooling body surface to form a cast steel strip, and then the corresponding cast steel strip is cold-rolled to a predetermined thickness and then finish-annealed. It was The present invention uses the slab obtained by this method as a raw material.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing an electromagnetic steel sheet which is extremely excellent as an iron core material for a stationary machine and which has a low iron loss in a limited two directions and an extremely high magnetic flux density. The purpose is to

[0005]

The feature of the present invention is that, by weight%, Si ≦ 4.0%, Al ≦ 2.0%, and (Si + 2Al)> 2.5%, and the balance: Fe and Molten steel consisting of unavoidable impurities (so-called non-transformed steel) is solidified by the moving and renewing surface of the cooling body to form a cast steel strip,
Next, in the method for producing an electromagnetic steel sheet in which the corresponding cast steel strip is cold-rolled to a predetermined thickness (final plate thickness) and then finish-annealed, in a slab thickness central layer 10
0} surface strength relative to random is 2.3 times or more, and the rolling ratio in cold rolling is 15% or more and less than 50%.

The present invention will be described in detail below. As a result of intensive studies to solve the technical problem in the present invention, the present inventors have obtained a casting ribbon directly from molten steel and have a {100 thickness parallel to the surface of the slab in the slab thickness center layer. } The surface strength is randomly set to 2.3 times or more, and the cold rolling ratio thereafter is set to 15
It was set to -50%, and the manufacturing method of the electrical steel sheet which was excellent in the bidirectional property limited by the primary recrystallization was found by annealing. We succeeded in obtaining a grain-oriented electrical steel sheet with a very high magnetic flux density in the limited two-direction and good iron loss.

Next, the component system will be described. In the present invention, in order to improve the mechanical properties of the product, the magnetic properties, the rust resistance, etc., or for other purposes, Mn, P, B,
The effect of the present invention is not impaired even if one or more Ni, Cr, Sb, Sn and Cu are contained. C is 0.
If it is 012% or less, the object of the present invention can be achieved. The non-oriented electrical steel sheet is mainly used in rotating machines, and from the viewpoint of stable magnetic characteristics, it is required that magnetic property deterioration (magnetic aging) does not occur during use of the non-oriented electrical steel sheet. . In the present invention, the solidification rate is high and the cooling rate after solidification is necessarily high, and C may form a solid solution in steel, which may cause magnetic aging during use in electric equipment.
In the product stage, it should be 0.0030% or less, but if C during casting is 0.012% or less, decarburization in the post process is relatively easy, so 0.012% or less. To do.

[0008] S is an element that is unavoidably mixed in during the melting stage of steel, and it is desirable that S be as low as possible in order to promote the growth of crystal grains in the final annealing and to reduce the pinning effect of magnetic domains in the product plate. . Therefore, it should be 0.008% or less. N, like S, is an element that is inevitably mixed in during the melting stage of steel, and in order to promote crystal grain growth in the final annealing and reduce the pinning effect of magnetic domains in the product plate, N should be as low as possible. desired. If it exceeds 0.006%, in addition to the above reasons, swelling (air bubbles, so-called blisters) may occur in the product plate. Therefore, N should be 0.006% or less.

Si is added to increase the specific resistance of the steel sheet and reduce the eddy current loss, as is well known in the art. If Si is added in excess of 4.0%, the workability is extremely deteriorated and cold rolling becomes difficult. Al, like Si, is added to increase the specific resistance of the steel sheet and reduce eddy current loss. For this purpose, a maximum of 2.0% Al has been added to non-oriented electrical steel sheets that have not been transformed so far. Although it is possible in principle to increase the addition amount, a maximum of 2.0 is taken into consideration in consideration of cold rollability as in Si.
%. Therefore, in this patent, the upper limit is specified in consideration of workability, and the lower limit is specified in consideration of the presence or absence of transformation, and Si and Al ranges by weight%, Si ≦ 4.0%, Al ≦ 2.0%, And (Si + 2Al)> 2.5%. Have a metamorphosis (S
In the case of i + 2Al) ≦ 2.5%, the same phenomenon as in the present invention has not been confirmed yet.

If the content of Mn is less than 0.1%, the workability of the product deteriorates, and Mn is added to render S harmless. However, the amount of Mn added is
If it exceeds 2.0%, the magnetic flux density of the product will be significantly deteriorated, so Mn ≦ 2.0% must be satisfied. P is added within the range of up to 0.1% in order to improve the punchability of the product. If P ≦ 0.2%, there is no problem from the viewpoint of magnetic properties of the product. B is added to render N harmless. Since the balance with the amount of N is necessary, the maximum content is set to 0.005%. If ultra low nitrogen steel is melted, N need not be added.

Next, the manufacturing process conditions of the present invention will be described. The inventors of the present invention have made a cast steel strip obtained by solidifying by a moving and renewing cooling body surface, a {100} plane strength parallel to the surface of the slab in the slab thickness center layer to 2.3 times at random. The cold rolling reduction rate is 15% or more and 50% or more.
It was found that the magnetic properties in a limited direction are improved by setting the ratio to be less than the above.

The reason for this is not yet clear, but the inventors' estimation will be described below. When a slab of non-transformed electromagnetic steel is obtained on the surface of a moving cooling body, at a certain cooling rate (solidification rate) or more, the structure during casting is a so-called columnar crystal (principal orientation {100} <0vw>). After cold rolling, the columnar crystals had a relatively low rolling reduction of 15% to 50%, and the columnar crystals had 4%.
It becomes a 5 degree cube ({100} <011>), and when this cold rolled texture is annealed, strain tends to accumulate.
The recrystallized grains easily grow in the degree cube, and a 45 degree cube is obtained as a recrystallized texture.

The range of the cold rolling reduction ratio strongly depends on the casting structure (including the texture of the cast slab). That is, it was also found that it depends on the degree of development of columnar crystals. In this way, the cold rolling reduction ratio is 15% or more and less than 50% (desirably 2
0% or more and less than 40%), the main orientation becomes {100} <011> after finish annealing, which is suitable for stationary equipment. However, it does not prevent its use in rotating machines. When the cold rolling reduction is high at 50% or more, the texture after casting (columnar crystals) is destroyed, and the texture after final annealing loses the characteristics of the slab obtained on the moving and renewing surface of the cooling body, The texture after finish annealing is the same as that of the conventional continuous casting + hot rolling method.

Production of a non-oriented electrical steel sheet in which a cast steel strip is solidified by a moving and renewing cooling body surface into a cast steel strip, and then the cast steel strip is cold-rolled to a predetermined thickness and then finish-annealed. In the method, the relationship between the cold rolling rate and the magnetic flux density (B ₅₀ (T)) for each direction was shown. Thus, the magnetism (B ₅₀ ) in the direction of 45 degrees from the rolling direction is 25% in the cold rolling reduction.
Up to 40% will be a plateau. In this case, a pair of random {10
The 0} plane strength was 4.5.

FIG. 2 shows the relationship between the random {100} strength of the slab center layer and the magnetic flux density (B ₅₀ (T): cold rolling reduction of 30%) in the direction of 45 ° from the rolling direction. . If the strength of the slab center layer against random {100} is 2.3 or more, it is considered that columnar crystals are considerably developed.
In this way, the 45-degree cube is developed. Further, as described below, various means have been devised for making the slab center layer a strength against random {100} of 2.3 or more, but the present invention does not matter.

As a method of increasing the {100} strength of the central layer of the cast slab to 2.3 or more, for example, ΔT (the degree of superheat of the molten metal) is increased (the method is as follows:
It is conceivable to raise the pouring temperature), obtain the desired texture at the time of solidification by improving the efficiency of heat removal at the solidification part, and freeze the desired texture to room temperature by rapid cooling immediately after solidification. Specifically, the temperature at the time of molten metal casting is raised. Then, use a material with a high thermal conductivity on the surface of the cooling body to be moved and updated.Forcefully cool the cooling body to be moved and updated with water etc. Shape it ・ Use an inert gas with high thermal conductivity as the atmosphere gas for casting ・ Consider a method to increase the heat removal rate by suppressing the liquid surface on the surface of the cooling body that dynamically moves and updates. Then, strong water cooling or strong gas cooling immediately after solidification can be considered.

[0017]

The embodiments of the present invention will be described below. The molten steel (comprising the balance Fe and unavoidable impurities) having the components shown in Table 1 is directly solidified on the surface of the cooling body for moving and renewing 0.60,
Steel strips of 0.70, 1.0, 1.5 mm and 2.0 mm were obtained. After that, pickling is performed, 0.40, 0.45, 0.5
Cold rolled to a thickness of 0 mm and 0.70 mm. The cold-rolled steel sheet is degreased and H ₂ = 30% in a continuous annealing furnace.
It was annealed at 975 ° C. for 30 seconds in a dry atmosphere of N ₂ = 70% (decarburization conditions were set as necessary). Then, the magnetic properties (average every 22.5 degrees) were measured by the Epstein method and are also shown in Table 1. By the way, it is the same heat as the number. Is a method of restraining the liquid surface on the surface of the cooling body that dynamically moves and updates (use of molten steel contact limiting plate),
Was cast by a usual method (without using the molten steel contact limiting plate). Was cast by a method of restraining the liquid surface on the surface of a cooling body that dynamically moves and updates (using a molten steel contact limiting plate), and immediately cooled to room temperature by water cooling immediately below the cooling body that moves and updates.

[0018]

[Table 1]

Manufacturing of a non-oriented electrical steel sheet in which a cast steel strip is solidified by the moving and renewing surface of the cooling body to form a cast steel strip, and then the cast steel strip is cold-rolled to a predetermined thickness and then finish-annealed In the method, by setting the rolling rate to 15% or more and less than 50% during cold rolling, it is possible to obtain a magnetic steel sheet having extremely excellent bidirectional magnetism. Desirably, it is 25% or more and 40% or less.

Further, FIG. 3 shows the texture after finish annealing of the embodiment. The cold rolling reduction rate is 35%. An ideal 45 degree cube is developed.

[0021]

EFFECTS OF THE INVENTION By the rapid solidification of molten steel, it is possible to manufacture a magnetic steel sheet for a static device having extremely excellent magnetic properties in specific two directions.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a cold rolling rate and B ₅₀ .

FIG. 2 is a diagram showing the relationship between the random {100} strength of the slab center layer and the magnetic flux density (B ₅₀ ) in the direction of 45 ° from the rolling direction.

FIG. 3 is a {100} positive electrode diagram of the material after finish annealing.

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[Procedure amendment]

[Submission date] February 15, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

FIG. 2 shows the relationship between the random {100} strength of the slab center layer and the magnetic flux density (B ₅₀ (T): cold rolling reduction of 30%) in the direction of 45 ° from the rolling direction. . If the strength of the cast slab center layer against random {100} is 2.3 or more, columnar crystals are considerably developed in areas other than the center layer.
(For example, if {100} strength is 0.7 or more,
That if there is), thus, 45 ° cubes are well developed. Further, as described below, various means have been devised for making the slab center layer a strength against random {100} of 2.3 or more, but the present invention does not matter.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

[0017]

The embodiments of the present invention will be described below. The molten steel (comprising the balance Fe and unavoidable impurities) having the components shown in Table 1 is directly solidified on the surface of the cooling body for moving and renewing 0.60,
Steel strips of 0.70, 1.0, 1.5 mm and 2.0 mm were obtained. After that, pickling is performed, 0.40, 0.45, 0.5
Cold rolled to a thickness of 0 mm and 0.70 mm. The cold-rolled steel sheet is degreased and H ₂ = 30% in a continuous annealing furnace.
It was annealed at 975 ° C. for 30 seconds in a dry atmosphere of N ₂ = 70% (decarburization conditions were set as necessary). Then, the magnetic properties (average every 22.5 degrees) were measured by the Epstein method and are also shown in Table 1. By the way, the numbers, and are the same heat. Is a method of restraining the liquid surface on the surface of the cooling body that dynamically moves and updates (use of molten steel contact limiting plate),
Was cast by a usual method (without using the molten steel contact limiting plate). Was cast by a method of restraining the liquid surface on the surface of a cooling body that dynamically moves and updates (using a molten steel contact limiting plate), and immediately cooled to room temperature by water cooling immediately below the cooling body that moves and updates.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

[0018]

[Table 1] ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 8, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

FIG. 2 shows the relationship between the random {100} strength of the slab center layer and the magnetic flux density (B ₅₀ (T): cold rolling reduction of 30%) in the direction of 45 ° from the rolling direction. . If the strength of the cast slab center layer against random {100} is 2.3 or more, columnar crystals are considerably developed in areas other than the center layer.
(For example, if the {100} intensity is 7.0 or more,
That if there is), thus, 45 ° cubes are well developed. Further, as described below, various means have been devised for making the slab center layer a strength against random {100} of 2.3 or more, but the present invention does not matter.

Claims (1)

[Claims] 1. By weight% Si ≦ 4.0%, Al ≦ 2.0% and (Si + 2Al)> 2.5% balance: Molten steel consisting of Fe and unavoidable impurities is solidified by a moving and renewing cooling body surface. At the very least, cast steel strip,
Then, the corresponding cast steel strip is cold rolled to a predetermined thickness,
In the production of a magnetic steel sheet for finish annealing, when the molten steel is a cast steel strip solidified by a moving and renewing surface of a cooling body, the thickness of the slab in the central layer of the slab is {10
0} surface strength relative to random is 2.3 times or more, and the rolling ratio in cold rolling is 15% or more and less than 50%. Production method.