JP3480072B2 - Method for producing silicon steel sheet with excellent magnetic properties - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a method for manufacturing a silicon steel sheet having a 0} plane and excellent magnetic properties.

[0002]

2. Description of the Related Art Conventionally, a silicon steel plate has been used as a magnetic core material for an electric motor, a generator or a transformer. This silicon steel sheet is required to have two characteristics, that is, a magnetic energy loss is small in an alternating magnetic field and a magnetic flux density is high in a magnetic field. In order to realize these characteristics, it is necessary to increase the electric resistance and <100 of the bcc lattice in the easy magnetization direction.
It is said that it is effective to integrate the> axis in the used magnetic field direction.

A unidirectional silicon steel sheet containing about 3% of Si is one that exhibits the most effective magnetic characteristics when the magnetic field direction used is limited to one direction (for example, a transformer).

FIG. 2 shows the rolling direction of a silicon steel sheet and bc.
<100> axis, <110> axis and {100} of c-lattice
It is a figure which shows typically the accumulation | orientation difference of a plane and {110} plane. The steel plate shown in Fig. 2 (a) is {110} as shown.
It is a unidirectional silicon steel sheet whose surface is parallel to the plate surface and whose <100> axis is integrated in the rolling direction. Since the easy magnetization direction of silicon steel is the <100> axis direction, this steel sheet has remarkably excellent magnetic properties when used by applying a magnetic field in the rolling direction. However, this unidirectional silicon steel sheet is hard to magnetize in a direction other than the rolling direction. Therefore, the desired effect cannot be obtained when the magnetic field acts in various directions on the plate surface as in a rotating machine such as an electric motor or a generator.

At present, it is a non-oriented silicon steel sheet having almost no texture that is used in a device in which a magnetic field acts in a plurality of directions of a plate surface. However, in such a silicon steel sheet, most of the <100> axes are not parallel to the plate surface, so that good magnetic characteristics cannot be obtained.

In these applications, good magnetic properties are exhibited by {100} as shown in FIGS. 2 (b) to 2 (d).
The surface is parallel to the plate surface, and the <100> axis is integrated in the direction perpendicular to the plate surface. With such a texture, up to two of the three <100> axes orthogonal to each other are integrated in the direction parallel to the plate surface. Hereinafter, in the present invention, these three types are collectively referred to as a silicon steel sheet having a {100} plane texture.

In this type of non-oriented silicon steel sheet, its application is changed according to the degree of accumulation of two <100> axes parallel to the sheet surface.

For example, in the case of an EI type iron core in which magnetic fields are applied in a direction perpendicular to each other in the plate surface, {100} <100> texture or {10} <100> shown in FIGS. 2 (b) and 2 (c).
0} <110> texture is desirable. In the case of an iron core to which a magnetic field is applied in all directions within the plate surface, whether the {100} plane shown in Fig. 2 (d) has a non-oriented texture in the plate surface,
Alternatively, a {100} plane shown in FIGS. 2B and 2C having a texture in one direction within the plate surface is punched at different angles within the plate surface, and these are stacked and used.

The inventors of the present invention, in Japanese Patent Laid-Open No. 1-108345, manufacture a silicon steel sheet using two-step decarburization annealing, which is suitable for realizing such a {100} plane texture on an industrial scale. Showed how.

In this manufacturing method, C: 0.02 to 1%, Si:
0.2 to 6.5%, and if necessary Mn: 5% or less is at least decarburized, then at a temperature of 850 ° C or less
-Cold-rolled silicon steel sheet having a plate thickness of 0.05 to 5 mm, which is included as a ferrite single phase, is decarburized to a temperature of substantially α-ferrite single phase after decarburization to C: 0.01% or less, and the plate surface is perpendicular. Direction, the silicon steel sheet is formed of columnar crystal grains that grow inward from the surface to the inside, and the <100> axis is densely integrated in the direction perpendicular to the sheet surface. “Substantially becoming an α-ferrite single phase” means that a trace amount of second phase such as MnS or AlN may be present.

In this method, essentially 5-50 μ from the surface
Primary decarburization annealing (for example, soaking and holding) in vacuum or weak decarburizing atmosphere to generate α-ferrite grains having <100> axis in the direction perpendicular to the plate surface in a region up to the depth of m. (Temperature: 950 ° C., soaking time: 5 hours), and then secondary decarburization annealing (for example, in a strong decarburizing atmosphere for growing the α-ferrite grains toward the center of the plate). Soaking and holding temperature: 850 ° C, soaking and holding time: 2 hours).

The factor that causes the α-ferrite grains having the <100> axis in the direction perpendicular to the plate surface to be formed at a high density on the surface of the plate is
The next is said to be. That is, when mild decarburization in a weak decarburizing atmosphere and Mn is added, deoxidation of Mn causes a γ → α transformation on the surface of the plate, which consists of only α-ferrite grains. To generate a region. Further, among the α-ferrite grains, those having a <100> axis in the direction perpendicular to the plate surface are selectively grown by the surface energy at which the {100} plane is most stable.

FIG. 4 is a diagram schematically showing the development of {100} plane texture. The above process is caused by selective growth because the surface energy of the {100} orientation α-ferrite crystal grains of the surface layer which is an α-ferrite single phase is smaller than that of other orientations.

The driving force for the selective growth by the surface energy is proportional to the ratio (ΔE / d) between the surface energy difference ΔE between the surrounding grains and the surface layer thickness d. Therefore, this driving force is large when the thickness of the surface layer that has become an α-ferrite single phase is thin, and the {100} plane texture occurs when the surface layer structure that became an α-ferrite single phase at the initial stage of annealing is thin. Develop. In other words, in order to develop the {100} plane texture, the surface layer that has become this α-ferrite single phase is formed quickly in the early stage of annealing, and decarburization or decarburization is performed for a sufficient time so that the surface layer does not become too thick. It is necessary to control Mn removal. If the boundary between the surface layer and the inside of the α-ferrite single phase is not clear, the {100} crystal grains in the surface layer will not grow efficiently.

[0015]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The method disclosed in Japanese Patent No. 45 uses an open coil method as the primary decarburizing annealing and an open coil method or a continuous annealing method as the secondary decarburizing annealing. The open coil method also causes a quality problem that the steel plate buckles during annealing.
In particular, the primary annealing is often performed at a high temperature of 900 ° C. or higher, so that long ones buckle significantly. In the continuous annealing method,
Since the annealing is relatively long, the annealing furnace becomes long,
There is a problem that equipment costs increase. Thus, the above method is not efficient in terms of productivity, manufacturing cost and quality.

The problem in performing the above-mentioned annealing process by annealing only once is that the primary annealing atmosphere has a very weak decarburizing effect and cannot be used as the secondary annealing atmosphere. In the strong decarburizing atmosphere of the secondary annealing, when Si or Mn in the steel sheet is strongly oxidized to form a surface oxide layer, if this is used as the primary annealing atmosphere, {10
The 0} plane texture does not develop. in this way,
Since the purpose and atmosphere of each annealing process are different, only a two-step annealing method can be adopted.

An object of the present invention is to provide a method capable of producing a silicon steel sheet having a {100} plane texture by a single annealing.

[0018]

DISCLOSURE OF THE INVENTION The inventors of the present invention sandwiched a material that promotes decarburization, or a material that promotes decarburization and a material that promotes deMn as an annealing separator between coil layers or between plates and anneal them. Is applied, a single annealing causes the γ → α transformation and forms a {100} plane parallel to the plate surface, and further α-ferrite grains grow toward the center of the plate The present invention has been completed based on the finding that the <100> axis can be formed in and the long steel plate can be manufactured without buckling.

The gist of the present invention resides in the following method of manufacturing a silicon steel sheet.

% By weight, C: 1% or less, Si: 0.2 to 6.5
%, Mn: 0.05 to 5.0% on a cold-rolled silicon steel sheet, using a substance that promotes decarburization as an annealing separator, decarburization annealing once in a tight coil or in a laminated state in a vacuum of 100 Torr or less. A method for producing a silicon steel sheet having a {100} plane texture with excellent magnetic properties, characterized in that the surface of the steel sheet is prevented from being oxidized .

% By weight, C: 1% or less, Si: 0.2 to 6.5
%, Mn: 0.05 to 5.0% in a cold rolled silicon steel sheet, using a substance that promotes decarburization and a substance that promotes demanganese as an annealing separator, in a tight coil or laminated state in a vacuum of 100 Torr or less. Oxidation of the steel sheet surface by decarburization annealing once
Excellent magnetic properties, characterized by subjecting to prevent the {1
A method of manufacturing a silicon steel sheet having a {00} plane texture.

[0022]

[Action]

I. Regarding the use of substances that promote decarburization as annealing separation materials: When a substance that promotes decarburization is alternately sandwiched between steel sheets as an annealing separation material and laminated, and tight coil annealing or laminated annealing is performed, the surface of the steel sheet is oxidized. Decarburization occurs while preventing it, and a strong {100} plane texture develops in the surface layer due to the γ → α transformation that occurs in this process. This decarburization reaction is sufficiently fast in practice, and by continuing annealing as it is, crystals having a {100} face texture are grown inside the plate within a practical annealing time, and the entire plate is {10}.
It can be composed of a 0} plane texture.

Examples of the substance that promotes the decarburization include Si oxide (SiO ₂ ).

The decarburization promoting action when SiO ₂ is used as the annealing separator is considered to be due to the following mechanism.

The Si oxide is stable at room temperature, but becomes unstable at a temperature of about 1000 ° C., and a decomposition reaction occurs according to the following formula to generate oxygen.

SiO ₂ → SiO + O ..... This oxygen reacts with carbon in the steel sheet according to the following formula to form carbon monoxide, resulting in decarburization.

O + C (in the steel plate) → CO (gas) ... According to the experiments by the inventors, the decarburization reaction of the formula seems to occur strongly at the contact point between the oxide and the steel plate. Is.
Then, the oxygen generated by the formula is oxygen gas (O ₂ ).
Instead of reacting with the carbon in the steel sheet after changing to
As shown in the equation, it seems that it is reacting with the carbon on the surface of the steel sheet in direct contact with the oxygen (O 2) state. That is, the above reaction has a strong solid reaction character.

In addition to the substances having the above-mentioned actions,
There are relatively unstable oxides such as Cr ₂ O ₃ , FeO, and Na ₂ CO ₃ under suitable atmosphere at high temperature. That is, it is a substance that decomposes at the annealing temperature to generate oxygen and promotes decarburization, or a substance containing these substances. These may be used as a mixture of two or more. One kind or two or more kinds may be mixed, and further, an inorganic substance stable at high temperature, for example, a stable oxide such as Al ₂ O ₃ or a stable nitride or carbide such as BN or SiC may be mixed.

However, Na ₂ CO ₃ is more unstable than SiO ₂ and has a high decomposition rate at high temperatures, so a large amount of oxygen is generated,
It oxidizes Si and Mn in the steel sheet, causing surface oxidation of the steel sheet.

Therefore, Na ₂ CO ₃ should be avoided alone or the amount of the mixture should be limited.

Most preferably, it contains SiO ₂ . Since SiO ₂ promotes decarburization without causing surface oxidation of the steel sheet in terms of its decomposition temperature and oxygen generation amount,
It is an optimal substance that promotes the development of {100} plane texture.

Oxygen (O) generated from the decarburization accelerator oxidizes Mn in the steel sheet and deteriorates the surface properties. Therefore, Mn
In the case of a steel sheet containing Mn, if a material that promotes Mn removal is used in combination with a decarburization accelerator, Mn, which is a γ-stabilizing element, decreases from the surface layer of the steel sheet, so that the γ → α transformation is promoted and Mn
Also suppresses the oxidation of. In addition, Mn that is not oxidized activates the surface of the steel sheet and accelerates the decarburization reaction according to the above formula.
Furthermore, Mn can be removed to accelerate the γ → α transformation on the surface.

The form of the annealing separator containing a substance that promotes decarburization is not particularly limited. This form may be a plate or a powder, a fibrous form thereof, a sheet-like form of the fibers, or a mixture of the powder and the sheet. Most desirable is a fibrous material or a fibrous sheet material. The reason for this is that carbon monoxide generated by the above reaction is easily discharged out of the coil due to the fact that there is no drop off from the coil layers and a large amount of adsorbed oxygen on the surface like powder, and because of the voids that exist between the fibers. And that Mn sublimes in the voids to promote the γ → α transformation on the surface. These can be easily sandwiched between coil layers or between plates.

II. Regarding the combined use of a substance that promotes decarburization and a substance that promotes Mn removal as an annealing separation material: When Mn is contained in the steel sheet, Mn sublimes from the surface of the sheet during annealing, which results in γ in the surface layer → It has been described that the α transformation is promoted and the development of {100} plane texture is promoted. Furthermore, we conducted a study focusing on the sublimation (de-Mn) of Mn, and by combining a substance that promotes de-Mn and a substance that promotes de-carburization as an annealing separator, a {100} plane texture can be formed more easily. It has been found that the degree of integration can be large. Here, a simple test result will be described.

FIG. 3 is a diagram showing the structure of the laminate during the annealing test. 1 is a laminated body, 2 is a trial plate, 3 is a de-Mn accelerator, 4
Is a decarburization accelerator. The laminate 1 is obtained by alternately stacking a trial plate 2 (Mn-containing silicon steel plate) and a de-Mn accelerating steel plate 3 (Mn-free, that is, a substance accelerating de-Mn) with a decarburization accelerator 4 as an annealing separator. Configured. If this is vacuum annealed (for example, 10
(00 ° C, 12h) Mn sublimated from the sample plate passes through the decarburizing accelerator as indicated by the arrow and is absorbed by the deprotonating Mn promoting steel plate. Such a reaction is that a large amount of Mn is present in the steel plate for promoting Mn removal after annealing, or the Mn removal of the trial plate is more than that in the case of annealing using only the decarburization promoting material without using the Mn promotion steel plate. Confirmed from the large amount.

In this way, promoting Mn removal is the first step (γ on the surface layer) that forms the {100} plane texture described above.
→ The α transformation is generated, and the {100} crystal grains are selectively grown in the surface layer by the surface energy to promote the {100} plane texture to develop laterally).

The substance that promotes Mn removal is an iron-based alloy containing no Mn, or an iron-based alloy containing Mn (preferably 1/2 or less of the Mn content of the silicon steel sheet) smaller than the Mn content of the silicon steel sheet, An oxide that absorbs Mn (for example, an oxide that forms a complex compound with Mn, TiO ₂ ) or the like. In any case, any substance that absorbs Mn sublimated from the steel sheet during annealing and does not adversely affect the decarburization reaction and the surface energy state of the steel sheet may be used. The shape may be powdery, fibrous, plate-like or the like and is not particularly limited. As for the composition component of the iron-based alloy, it is preferable that the Mn content is 1/2 or less of the Mn content of the silicon steel sheet, and the other components are equal.

TiO _{2, which} is an oxide that promotes Mn removal, forms a complex oxide (TiMnO ₂ ) with Mn that sublimes from the steel sheet, and absorbs Mn. The oxide that promotes Mn removal can be mixed with an annealing separator for promoting decarburization, and decarburization annealing can be performed more effectively than an iron-based alloy sheet. The {100} plane texture generation mechanism in the case of annealing using both the decarburization promoting material and the Mn depromoting material will be described.

FIG. 5 shows C due to diffusion when the steel sheet is annealed.
3 is a schematic diagram showing the concentration distributions of Mn and Mn, where C is the concentration distribution when only decarburization is performed and Mn is the concentration distribution when Mn is removed. If annealing is performed near 1000 ° C and only decarburization proceeds,
Although such a carbon concentration distribution is formed, since the diffusion rate of carbon is very large, the difference in the carbon concentration between the surface and the inside is small, and the surface structure of α-ferrite single phase is not formed or is formed. However, the boundary between the surface layer structure (structure that became α-ferrite single phase) and the internal structure (α + γ structure or γ structure) became unclear, and the thickness of the surface layer structure was thick enough to provide a {100} plane texture. Cannot be developed.

On the other hand, the diffusion rate of Mn is much smaller than that of carbon, as shown in FIG. 5, and a large concentration gradient was generated in the vicinity of the surface due to Mn removal (the boundary between the surface layer of low Mn and the interior of high Mn). Clear Mn region can be formed.

The decrease in Mn content due to the annealing using the de-Mn accelerator promotes the chemical potential of carbon in the region, and as a result, the carbon in the region (surface layer of low Mn) becomes high in carbon.
Mn is diffused into the region (inside the plate), γ → α transformation occurs in that region, and that region is made into α-ferrite single phase.
The surface layer formed by de-Mn does not become so thick even after long-time annealing because the diffusion rate of Mn is low (10
(Approximately 100 μm even when annealed at 00 ° C for 12 hours). Therefore, the annealing (1000 ° C, 12
h) Then, due to Mn removal in the initial stage, the surface layer (from 20 μm)
A surface layer of α-ferrite single phase is formed in about 70 μm), and when decarburization progresses sufficiently later, this surface layer portion grows inward. By keeping the surface texture of the clear α-ferrite single phase in a thin state, the {100} crystal grains grow by the surface energy and the {100} plane texture is strongly developed.

When a silicon steel sheet and an annealing separator are stacked and annealed, a difference in Mn removal amount occurs between the central portion and the end portion of the silicon steel sheet, which may make the magnetic characteristics unstable. It can be reduced by using Mn accelerator.

FIG. 6 and FIG. 7 are micrographs of the microstructures obtained when the materials having different Mn values obtained in the examples were annealed by using both the decarburizing accelerator and the Mn accelerator.

FIGS. 6 (a) to 6 (e) show changes in the microstructure of a silicon steel sheet containing 0.92% Mn (steel type F) depending on the annealing time. Annealing time is 1 due to the effect of removing Mn
Within the time ((a) and (b)), there is a clear α-ferrite single phase region near the surface of the steel sheet. When the annealing time became longer (3 hours, (c)), the crystal grains of the surface layer rapidly grew in the form of columnar grains, and the columnar grains grown from both surfaces collided in the central part of the plate thickness. It becomes such an organization. Further, it can be seen that the grain growth progresses as the annealing time becomes longer (6 to 12 hours, (d) and (e)).

FIGS. 7 (a) to 7 (e) show changes in the microstructure of a silicon steel sheet containing no Mn (steel type OM) depending on the annealing time. In Mn-free steel, there is no Mn removal effect, so a clear surface layer is not formed, decarburization progresses uniformly throughout the plate thickness, and grain growth occurs almost in the vicinity of the plate surface and inside. .

III. Annealing: The cold-rolled steel sheet to which a material that promotes decarburization and Mn removal is applied as an annealing separator may be either a coiled sheet or a cut sheet. The former case corresponds to tight coil annealing, and the latter case corresponds to laminated annealing.

When the cold-rolled steel sheet has a coil shape and a sheet-shaped annealed separation material is used in actual operation, a method of stacking it on a cold-rolled steel sheet and winding it in a coil shape is preferable. When the oxide powder is applied to the cold-rolled steel sheet, it can be applied before being wound by the winding device. By the tight coil annealing using the annealing separator having such a form, it is possible to manufacture a long steel plate without buckling.

The annealing atmosphere is a vacuum of 100 Torr or less.
It More preferred is a vacuum of 1 Torr or less. When the atmospheric pressure exceeds 100 Torr, the desired oxygen separation reaction, decarburization reaction, and {100} plane texture with a high degree of integration are less likely to occur.

The holding temperature is preferably 1300 ° C. or lower. 1300 ° C
Annealing temperatures above 10 are difficult to achieve industrially.
In order to obtain a highly-integrated {100} plane texture, it is preferable to use the α + γ two-phase coexistence temperature range of 850 ℃ or higher or γ
It is the phase temperature range.

The soaking time for annealing is 30 minutes to 100
Good time range. If it is less than 30 minutes, decarburization or Mn removal is insufficient. On the other hand, productivity exceeds 100 hours.

IV. The reason why the chemical composition of the cold-rolled silicon steel sheet which is the raw material of the method of the present invention is determined as described above will be explained.

C: In decarburization annealing, in order to suppress the time required for decarburization and to control the texture utilizing the γ → α transformation accompanying decarburization, the C content is the raw steel sheet before decarburization annealing. Therefore, it must be 1% or less. The lower the C content, the better. The preferable upper limit of the C content is 0.5%, and more preferable is 0.2%. Further, in order to exert the effect of decarburization, it is preferably set to 0.01% or more. Thus, the C content in the stage after annealing should be less than 0.01%, preferably 0.005% or less, and more preferably 0.003% or less in order not to deteriorate the magnetic properties. Remaining C
Is because it precipitates as cementite in α-ferrite and deteriorates the magnetic characteristics.

Si: A Si content of 0.2% or more is required to secure magnetic properties and mechanical properties. 1% or more is preferable. On the other hand, the upper limit of the Si content was set to 6.5% in order to suppress embrittlement and decrease in magnetic flux density. It is preferably 5% or less, more preferably 4% or less.

Mn: Effect of increasing electrical resistance to reduce eddy current loss, γ
Effect of facilitating control of texture using γ → α transformation by expanding phase temperature range, effect of developing {100} plane texture, and effect of activating the steel sheet surface during annealing to promote decarburization Therefore, it is necessary to add 0.05% or more. Preferably 0.3% or more, more preferably
It is 0.5% or more. In any case, 850 ℃ after decarburization is completed
It is desirable to contain the maximum amount of the α-ferrite single phase at the following temperatures. This is because if Mn is contained in a large amount, the temperature at which the α-ferrite single phase is substantially reduced after decarburization is completed, and the annealing temperature must be extremely lowered. Here, "substantially becomes an α-ferrite single phase" means that a trace amount of second phase such as MnS or AlN may be present as in the above.

When the Si content is high, Mn can be increased, but it is preferable that the Mn content does not exceed 5% in order to reduce the magnetic flux density.

Elements other than the above which can be contained without impairing the effects of the present invention are as follows.

Al: 0.5% or less, W, V, Cr, Co, Ni, M
o: 1% or less for each, Cu: 0.5% or less, Nb: 0.5% or less, N: 0.05% or less, S: 0.5% or less, Sb, Se, As:
Each is 0.05% or less, B: 0.005% or less, P: 0.5% or less. Such a material steel sheet composition is a decarburization accelerator, and an annealing separator composed of a decarburization accelerator and a Mn accelerator is used between coil layers or between sheets. Sandwiched between the two and decarburized and annealed in a tight state, the following (a)
The action and effect of (c) can be obtained.

(A) Since the oxygen to be supplied is only the oxygen generating substance which also serves as the annealing separator, the density of the annealing separator can be selected so that the excess oxygen is not supplied. Here, the density of the annealed separator is represented by the mass per unit area, and in the case of a sheet, it is proportional to the thickness. Also,
Since the oxygen generation amount changes depending on the annealing temperature, it can also be controlled by this temperature. Oxidation of the steel sheet surface can be sufficiently prevented by such controlled filling of the annealing separator and supply of oxygen.

[0059] Particularly, when decarburization promoting material is an oxide such as SiO _2, the decomposition of the SiO ₂ when the oxygen content increases does not occur. That is, the oxygen decomposition reaction of the above formula stops or progresses in the opposite direction, and the increase in oxygen amount stops or conversely decreases. This reaction automatically controls Si in the steel sheet so that it is not oxidized. As for Mn, since the oxidation potential of Mn is very close to that of Si, Mn is also not oxidized.

By controlling the amount of oxygen in such a limit region of oxidation, sufficient decarburization proceeds under oxygen supply conditions in which oxidation of Si and Mn does not occur.

(B) As described above, since the decarburizing reaction has the character of a solid reaction, unlike the reaction between gas and carbon in the steel sheet as in the case of open coil annealing, low oxygen supply is required. A high decarburization rate is maintained even under the conditions.

(C) By the above (a) and (b), the decarburization reaction proceeds so fast that there is no practical problem, and the need for two-step annealing is eliminated.

The production of a silicon steel sheet is usually carried out by the steps of continuous casting-hot working-cold rolling.

Other than the method of continuous casting, for example, 50 mm
A method of cold rolling directly or after hot working of a thin slab directly solidified to the following plate thickness or an ultrathin plate by a melt quenching method may be used.

The cold rolling may be performed by any rolling method as long as cold rolling with a reduction rate of 10% or more is performed. A preferable rolling reduction is 30% or more, and a more preferable rolling reduction is 50% or more. In this case, it is possible to prevent the annealing from being performed once or a plurality of times during the hot working and subsequent workings. Here, cold rolling means rolling at 500 ° C. or lower at which recrystallization does not occur.

The plate thickness after cold rolling is preferably 5 mm or less. If the plate thickness exceeds 5 mm, it takes a long time to decarburize the inside, and eddy current loss increases. 1mm is preferable
Hereafter, it is more preferably 0.5 mm or less. On the other hand, the lower limit of the plate thickness is not particularly limited as long as it can be manufactured by cold rolling.

[0067]

【Example】

[Example 1] Ingots of nine kinds of chemical compositions shown in Table 1 obtained by vacuum casting were hot forged into a steel plate having a thickness of 10 mm,
Further, each steel sheet was hot-rolled to a thickness of 3 mm and then cold-rolled to a thickness of 1 mm. Five 250 mm square test plates were cut out from each of these cold-rolled steel plates, and used as test materials for simulating tight coil annealing.

To control the texture, 48% by weight of Al ₂ O ₃ -51% by weight of SiO ₂ fibrous decarburizing accelerator was added as an annealing separator between each of 5 trial plates at 0.02 g / cm ² . Sandwiched by density, laminated,
Shown in Table 2 in vacuum of 10 ^-2 Torr 925 ~ 1100 ℃, 3 ~ 72
Decarburization annealing was carried out under the condition of time.

(Measurement of Texture) X-ray integrated intensity measurement was carried out at a position of 2/5 of the plate thickness from the surface of each sample plate after decarburization annealing, and the plate surface was obtained from the integrated intensity of {200} plane reflection. The <100> axial density in the vertical direction was determined as a multiple of the sample having no orientation. In addition, OM steel in Table 5 described later was used as a de-Mn accelerator, and as shown in FIG. 3, the decarburization accelerators were alternately laminated and the same measurement was performed. The results are shown in parentheses in Table 2. For comparison, the same measurement was performed on a commercially available high-grade non-oriented silicon steel sheet (JIS S-9) with a thickness of 0.5 mm.

(Analysis of C and Mn contents after decarburization annealing)
The carbon content and Mn content in each sample plate after decarburization annealing were analyzed.

The results are shown in Table 2.

[0072]

[Table 1]

[0073]

[Table 2]

From Table 2, it can be seen that the steel sheet produced by the manufacturing method of the present invention has a strong {1
It can be seen that the 00} plane texture is formed.

Example 2 A 3 mm-thick hot-rolled steel sheet of I steel shown in Table 1 was cold-rolled to a 0.35 mm-thick steel sheet, and a 200 mm square trial plate was cut out from the obtained steel sheet. A decarburization accelerator as shown in Table 3 was sandwiched between the five test plates and laminated, and a surface pressure of 0.1 kg / cm ² was applied to the laminated body to 1 Torr.
Decarburization annealing was performed at 1,050 ° C. for 24 hours in the vacuum.

(Measurement of Magnetic Properties) Ten ring-shaped test pieces each having an inner diameter of 33 mm and an outer diameter of 45 mm were punched out from each of the test plates that had been decarburized and annealed, and the punched strain was maintained at 800 ° C. for 30 minutes in nitrogen gas. Removed. The 10 ring-shaped test pieces were laminated, and a primary coil and a secondary coil were wound around this for 100 turns to measure magnetic characteristics. Magnetic flux density (B ₅₀ ) when an external magnetic field of 5000 A / m is applied (to the primary coil) and iron loss (W _15/50 ) when magnetized to a magnetic flux density of 1.5 T (Tesla) in an alternating magnetic field of 50 Hz. ) And asked. Commercially available 0.35 for comparison
The same measurement was performed on a high-grade non-oriented silicon steel sheet (JIS S-9) with a thickness of mm. The results are also shown in Table 3.

[0077]

[Table 3]

As is clear from Table 3, except for the case where only Al ₂ O ₃ having no decarburization promoting action was used as the annealing separator, the amount of carbon was reduced by one annealing and excellent magnetic properties were obtained. Has been obtained.

Example 3 A 4 mm thick hot rolled steel sheet of G steel shown in Table 1 was cold rolled to a thickness of 2 mm, then subjected to intermediate annealing at 900 ° C. for 3 minutes and then cold rolled. As a steel plate having a thickness of 0.35 mm, a 200 mm square test plate was cut out from the obtained steel plate.

Between each of the five trial plates, 70
Wt% Al ₂ O ₃ -29 wt% SiO ₂ -based fibrous decarburization accelerator is sandwiched at a density of 5 mg / cm ² and laminated, and a surface pressure of 0.1 kg / cm ² is applied to the laminate, and Table 4 Under various vacuum atmospheres shown in
Decarburization annealing was performed at 00 ° C for 6 to 72 hours.

Example 2 was carried out on the test plate which had been decarburized and annealed.
The same evaluation test as above was performed. The results are also shown in Table 4.

[0082]

[Table 4]

As is clear from Table 4, in the method of the present invention, the amount of carbon is reduced by one annealing, and excellent magnetic characteristics are obtained.

Example 4 The same 200 mm square sample plate as in Example 2 was cut out from the steel plate obtained by cold rolling the B steel shown in Table 1 to a thickness of 0.35 mm. As an annealing separator, fibrous decarburization accelerator of 50 wt% Al ₂ O ₃ -50 wt% SiO ₂ system was sandwiched between each of 5 test plates at a density of 25 mg / cm ² , and the same procedure as in Example 2 was performed. By the way
Decarburization annealing was performed at 975 ° C for about 20 hours. The carbon and Mn analysis was performed on the sample plate during the decarburization annealing, and FIG. 1 is a diagram showing the influence of the annealing time on the carbon and Mn contents. As shown in the figure, it can be seen that decarburization and Mn removal are efficiently performed in the method of the present invention.

Example 5 Shown in Table 5 obtained by vacuum casting.
Ingots of 18 different chemical compositions were hot-forged into a steel plate having a thickness of 50 mm, each steel sheet was hot-rolled to a thickness of 3 mm, and then cold-rolled to a thickness of 0.35 mm. H after the steel type symbol
Steels marked with are carbon-free steels and have almost the same composition as steels without H except for the carbon content.
Is a steel containing no Mn and was used as a steel sheet for promoting Mn removal.

[0086]

[Table 5]

From each of these cold-rolled steel sheets, five 400 mm square test sheets were cut out to obtain test materials for simulating tight coil annealing.

In order to control the texture, 48% by weight of Al ₂ O ₃ -51% by weight of SiO ₂ -based fibrous decarburization accelerator was added as an annealing separator between each of 5 test plates at a density of 0.02 g / cm ² . Sandwich and stack, 10
Decarburization annealing was carried out in a vacuum of ^-3 Torr at 950 to 1150 ° C for 0.5 to 72 hours.

The composition of the fibrous decarburization promoter is close to that of an oxide called mullite, and it was found from X-ray diffraction that most of the composition had an amorphous or mullite crystal structure. There is. After use as an annealing separator, it was almost always a mixture of mullite and a small amount of cristobalite.

In order to know the effect of de-Mn, a laminated body of each sample plate and decarburization accelerator (without de-Mn material), and each sample plate, decarburization accelerator and de-Mn acceleration steel plate as shown in FIG. Annealing was performed on two types of laminates of the (OM) laminate.

The center portion of the 400 mm square sample that had been decarburized and annealed
For each test plate cut out from a 100 mm square part, X-ray integrated intensity measurement was performed at the position of 2/5 of the plate thickness from the surface,
The <100> axial density was calculated from the {200} area intensity as a multiple of the sample having no orientation. Further, the carbon content, the Mn content and the magnetic properties were determined by the same method as in Examples 1 and 2. For comparison, the same evaluation was performed on a commercially available high-grade non-oriented silicon steel sheet (JIS S-9, S-20) having a thickness of 0.35 mm.

The results are shown in Table 6. In Table 6 ()
The values inside are the values when no steel sheet for promoting Mn removal is used.

The steels from J to T shown as invention examples in Table 6 are Mn-free OM steel and carbon-free JH steel to SH when decarburized and annealed under the conditions shown in the same table. Higher {200} integral strength and higher B ₅₀ than steel
_15/50 is low, and the {100} plane texture is strongly developed and excellent magnetic properties can be obtained.

[0094]

[Table 6]

When the Mn accelerating agent was used in combination, the Mn content of each test plate was lower than that in the case where it was not used together.
It can be seen that the steel sheet (OM) used as the Mn promoter is absorbed.

Also by this, the magnification of {200} integrated intensity and B ₅₀ are high, and W _15/50 is low,
It can be seen that the {100} plane texture is strongly developed and excellent magnetic properties are obtained.

Further, it can be seen that magnetic characteristics equivalent to or higher than those of the high Si content steel shown in the reference example are obtained.

From Table 6, it can be seen that the steel sheet produced by the production method of the present invention has a strong {1
It can be seen that the 00} plane texture is formed.

[Example 6] 3 of composition shown by steel type O in Table 5
mm hot-rolled steel sheets with various thicknesses (0.15-0.5 m
A 400 mm square plate was cut out from the steel plate obtained by cold rolling to m), and a test was performed using TiO ₂ powder as a Mn removal promoting material. 70% by weight Al ₂ O ₃ -30% by weight SiO ₂
A variety of TiO ₂ powders with a particle size of 10 to 50 μm added to a fibrous decarburization accelerator of the system, sandwiched at a density of 0.01 g / cm ² and laminated, with a surface of 0.2 kg / cm ² on the laminate. Annealing was carried out by applying pressure and soaking at 1050 ° C. for 6 hours in a vacuum of 10 ⁻¹ Torr. The heating rate was 1 ° C / min. In the same manner as in Example 5, <100> axial density, carbon and Mn contents were analyzed. The results are shown in Table 7.

[0100]

[Table 7]

As is clear from Table 7, the use of TiO ₂ powder also promotes de-Mn removal and strongly develops the {100} plane texture.

[Example 7] The texture and in-plane magnetic anisotropy of the annealed samples shown in Table 3 No. 3 were examined.

FIG. 8 is a {110} pole figure showing the formation of a strong {100} <052> texture, and the texture of the annealed sample shown in Table 7 No. 3 is α by Co-Kα ray. −Fe
It is measured by using 110 reflections. The <110> axial density is very large in 8 directions inclined by 45 ° from the plate vertical direction, and this material has a strong {100} plane texture, and the {100} plane texture is {100} <0.
It can be seen that it has a 52> type in-plane anisotropy.

FIG. 9 is a diagram showing the relationship between the rolling direction of the material and the magnetic flux density and iron loss value.

A width of 3 cm from the material after annealing shown in 3 in Table 7,
A strip-shaped sample having a length of 10 cm was cut so that the longitudinal direction was various rolling directions. The magnetic flux density (B ₁₀ ) and iron loss value (W _15/50 ) of the sample at a magnetizing force of 1000 A / m were measured by a single-plate magnetization measuring device. From Figure 9 {100}
Reflecting the <052> type texture in-plane anisotropy, it can be seen that the magnetic flux density in the direction inclined by 45 ° from the rolling direction is the largest and the iron loss value is also small in the same direction. However, the absolute value of this in-plane magnetic anisotropy is about the same as that of commercially available non-oriented silicon steel sheets, and is suitable for iron core materials for electric motors and the like. In the single cold rolling method, this type ({100} <052>
In-plane anisotropy of (type) is likely to occur, and when annealed after two or more cold rollings with intermediate annealing sandwiched, {100} <00
1> type in-plane anisotropy is likely to appear.

[Embodiment 8] A vacuum-melted ingot having a composition shown by the steel type N in Table 5 was hot forged into a plate having a thickness of 30 mm.
After hot rolling each plate to a thickness of 3 mm, 900 mm in nitrogen gas
After annealing at 0 ° C for 3 minutes, it was cold-rolled to a plate thickness of 0.5 mm. To simulate tight coil annealing,
A 400 mm square sample plate was cut out from the cold-rolled plate and filled with 20% by weight Al ₂ O ₃ -80% by weight SiO ₂ -based fibrous decarburization accelerator as an annealing separator at a density of 0.005 g / cm ^2. , And 3 mg / c of SiO ₂ and TiO ₂ powder having a diameter of 5 μm to 100 μm respectively.
It is sandwiched between test plates at a density of m ² and laminated, and 0.2 kg / c
A surface pressure of m ² was applied.

The annealing was soaked in a vacuum of 10 ^-2 Torr at 1000 ° C for 10 hours, and the temperature rising rate was 1 ° C / min. X-ray integral strength measurement was performed at the position of 2/5 of the plate thickness from the surface of each annealed sample plate, and the strength for the {200} area was obtained as a multiple of the sample without orientation, and the <100> axial density was calculated. It was judged. In addition, the carbon and Mn contents in each annealed sample plate were analyzed, and 10 ring-shaped test pieces with an inner diameter of 33 mm and an outer diameter of 45 mm were punched out from each sample plate at 800 ° C in nitrogen gas.
It was held for 30 minutes to remove punching distortion.

Ten ring-shaped test pieces were laminated, and a primary coil and a secondary coil were wound around each by 100 turns, and 1000 A / m
And magnetic flux density when an external magnetic field of 5000 A / m is applied
(B ₁₀ and B ₅₀ ) and iron loss (W _10/50 and W _15/50 ) when magnetized to a magnetic flux density of 1 T (tesla) and 1.5 T in an alternating magnetic field of 50 Hz were measured. The magnetization curve of the sample is shown in FIG. 10 together with that of the comparative material (commercial non-oriented electrical steel sheet S-9), and other magnetic properties and the results of the above-mentioned various analyzes are shown in Table 8.

[0109]

[Table 8]

It can be seen that excellent magnetic properties can be obtained by the method of the present invention.

[0111]

EFFECTS OF THE INVENTION According to the method of the present invention, one-time tight coil annealing or laminated annealing provides excellent magnetic properties {1.
A silicon steel sheet having a high degree of {00} plane integration can be efficiently manufactured. Since the annealing is performed by the tight coil annealing or the laminated annealing using the annealing separation material, the buckling of the steel sheet is eliminated and the long material can be manufactured.

[Brief description of drawings]

1 shows carbon and annealed steel sheet according to the method of the invention and
It is a figure which shows the influence of the annealing time which acts on the content of Mn.

FIG. 2 is a diagram schematically showing a difference in crystal orientation between a grain-oriented and a non-oriented silicon steel sheet.

FIG. 3 is a diagram showing a laminate in which tight annealing is reproduced with a decarburization promoting material and a deMn promoting material sandwiched therebetween.

FIG. 4 is a diagram for explaining generation of {100} plane texture when annealed using a decarburization accelerator and a Mn accelerator.

FIG. 5 is a diagram showing a diffusion state of C and Mn by annealing.

FIG. 6 is a diagram showing a comparison of crystal grain growth during annealing.

FIG. 7 is a diagram showing a comparison of crystal grain growth during annealing.

FIG. 8 is a {100} pole figure showing the formation of a sharp {100} <052> texture.

FIG. 9 is a diagram showing in-plane anisotropy of magnetic flux density and iron loss.

FIG. 10 is a diagram showing the relationship between magnetizing force and magnetic flux density.

[Explanation of symbols]

1. Laminate 2. Trial plate (silicon steel plate)
3. De-Mn promoting material 4. Decarburization accelerator

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C21D 8/12 C21D 9/46 501 C22C 38/00-38/60 H01F 1/16-1/18

Claims (2)

(57) [Claims] 1. By weight%, C: 1% or less, Si: 0.2 to 6.5
%, Mn: 0.05 to 5.0% on a cold-rolled silicon steel sheet, using a substance that promotes decarburization as an annealing separator, decarburization annealing once in a tight coil or in a laminated state in a vacuum of 100 Torr or less. A method for producing a silicon steel sheet having a {100} plane texture with excellent magnetic properties, characterized in that the surface of the steel sheet is prevented from being oxidized . 2. By weight%, C: 1% or less, Si: 0.2 to 6.5
%, Mn: 0.05 to 5.0% in a cold rolled silicon steel sheet, using a substance that promotes decarburization and a substance that promotes demanganization as an annealing separator, and in a tight coil or laminated state in a vacuum of 100 Torr or less. Oxidation of the steel sheet surface by decarburization annealing once
Excellent magnetic properties, characterized by subjecting to prevent the {1
A method of manufacturing a silicon steel sheet having a {00} plane texture.