JP3013000B2 - Method for manufacturing bidirectional silicon steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a bidirectional silicon steel sheet.

[0002]

2. Description of the Related Art An iron-based material is characterized in that the energy state of electrons carrying magnetism differs depending on the direction with respect to the crystal axis, and the material is easily magnetized in the direction of the Miller index <100> axis. Utilizing this crystal magnetic anisotropy, a unidirectional magnetic steel sheet used for a magnetic core of a transformer or the like has a Miller index of ｛11.
Only crystal grains expressed as 0｝ <001> (referred to as Goss orientation) were selectively grown, and the magnetic permeability in one direction in the plane of the steel sheet was dramatically improved.

[0003] The grain-oriented electrical steel sheet ({110} <00
1>) in two orthogonal directions in the plane of the steel sheet.
Biaxially oriented electrical steel sheet with oriented axis (mirror index of $ 10
0｝ <001> or {100｝ <011>) is a more ideal soft magnetic material. However, in spite of the complicated industrial process, sufficient magnetic properties cannot be obtained, so that the bidirectional magnetic steel sheet has not been widely used as a core material.

[0004] Conventional methods for producing a bidirectional magnetic steel sheet are roughly classified into the following three methods. 1) Method using a directional ingot composed of columnar grains This method is based on the development of columnar grains while maintaining a temperature gradient, as disclosed in JP-B-33-7509 or JP-B-33-7952. This is a method in which a prepared ingot is manufactured, cold-rolled in a direction that satisfies a certain angular relationship with the elongation direction of the columnar grains, and recrystallized. The point of this method is that the deviation from the {100} <001> direction of the material is as shown in JP-B-33-7953.
{100} after cold rolling and recrystallization if within a certain tolerance
<001> orientation.

2) Method using surface energy This method is disclosed in JP-B-36-8554 and JP-B-37.
As disclosed in JP-A-7110 or JP-B-38-16212, the heat treatment atmosphere is controlled when cold rolling and recrystallizing a thin material, and the crystal grains having a {100} plane on the surface of the material. This is a production method characterized in that only the recrystallization is performed.

3) Cross cold rolling method This method involves cold rolling a silicon steel material in one direction as disclosed in Japanese Patent Publication No. 35-2657 and then cold rolling in a direction crossing the cold rolling. Cold rolling, short annealing and 9
This is a method of performing high-temperature annealing at 00 to 1300 ° C. The principle of this method is to develop a texture which becomes a base on which {100} <001> oriented grains are easily grown by cross cold rolling,
A {100} <001> orientation grain is developed by secondary recrystallization using an inhibitor of grain growth such as N.

[0007]

As described above, as described above,
Although the bidirectional electrical steel sheet is an ideal magnetic material in which two of the three easy axes are oriented in the plane of the steel sheet, it has hardly been used industrially to date. This is because it is extremely difficult to industrially perform the manufacturing method proposed up to now, but it is not possible to obtain the degree of integration of the crystal orientation as expected.

For example, in the method using a directional ingot of 1), in order to sufficiently develop columnar grains, it is necessary to cool the bottom face while heating the side face of the mold and to give a temperature gradient to the molten steel. It was extremely difficult to perform mass production as a simple process. In the method using surface energy of 2), strictly controlling the atmosphere of the heat treatment so that only {100} grains grow is
It is industrially difficult, and in principle, the <100> axis direction in the plate surface cannot be aligned.

In the method 3) using the cross-rolling, it is possible to obtain a considerably high crystal orientation and a considerably high magnetic permeability in two directions in the plate surface, but it can be said that a sufficiently high degree of integration was obtained. Absent.

[0010]

As described above, the method using the cross cold rolling can obtain a considerably high crystal orientation. The present inventors have devised a method for producing a bidirectional silicon steel sheet having a higher magnetic permeability by improving this method. It is widely known that even if a silicon steel single crystal having a {100} <011> orientation is rolled and annealed in the <011> direction, recrystallization does not occur and its crystal orientation does not change (for example, Wada et al. Japan Journal of the Japan Institute of Metals 32 (1968)
767).

The present inventors further determined that a silicon steel sheet in which the deviation of one <100> axis from the vertical direction of the plate surface is within 15 ° is less than the vertical direction of the <011> axis perpendicular to this direction. It has been found that a bidirectional silicon steel sheet having a high degree of integration can be obtained when it is rolled and annealed in a direction within 15 ° with respect to the projection on the sheet surface. By utilizing this phenomenon, it is possible to improve the magnetic permeability of a bidirectional silicon steel sheet having a relatively high magnetic permeability obtained by a process using cross cold rolling and obtain a bidirectional silicon steel sheet having a higher magnetic permeability. Can be.

Further, the present inventors have found that when a hot-rolled sheet is annealed at 700 to 1200 ° C. in the process using the above-described cross cold rolling, a silicon steel sheet well integrated in the {100} <001> orientation Was obtained, but when the hot-rolled sheet was not annealed, it was found that the heat-rolled sheet was rather well accumulated in {100} <011>. By combining these phenomena, a bidirectional silicon steel sheet having an extremely high degree of integration in the {100} <011> orientation can be manufactured.

Hereinafter, the present invention will be described in detail. As a component of the silicon steel sheet, the lower limit of the Si component is set to 1.8% in order to suppress the destruction of the crystal structure due to the α-γ transformation. Further, 6.8% is specified as an effective upper limit for reducing eddy current loss in an alternating magnetic field. When the Si content is 4.8% or more, cracks are likely to occur during cold rolling, but since rolling can be performed by rolling during warm rolling, the upper limit is specified.

As for the other components, Al has an amount of AlN necessary to suppress normal grain growth and secure a sufficient driving force for grain growth up to a high temperature in order to perform stable secondary recrystallization.
The lower limit is limited to 0.010% as an amount sufficient for the precipitation of, and the secondary recrystallization becomes unstable if the content exceeds 0.050%, so the upper limit is defined. N is also A
Although it is an element necessary for the precipitation of 1N, it can be supplemented by nitriding from an atmosphere gas or the like before the secondary recrystallization, so that the lower limit that can be economically reduced from molten steel is 0.0
01% was specified. If it exceeds 0.0120%, it does not dissolve in molten steel and causes defects in the steel slab, so the upper limit was made 0.0120%.

In addition, MnS, Cu ₂ S, MnSe, Nb (C, N),
One or more selected from Sn, Sb and the like can be included in a known range. The silicon steel slab composed of the above components is heated and hot rolled. Next, cold rolling is performed at a rolling reduction of 40 to 80%, and further cold rolling is performed at a rate of 30 to 70% in a direction perpendicular to the cold rolling. This cold rolling is equivalent to that disclosed in Japanese Patent Publication No. 35-2657. Furthermore, this steel sheet was used for the purpose of primary recrystallization.
Short-time annealing at 50 to 1000 ° C. is performed, followed by annealing at 900 to 1300 ° C. for the purpose of secondary recrystallization and purification. These annealings are equivalent to those disclosed in Japanese Patent Publication No. 35-2657.

The present inventors have found the following in these processing steps. That is, before cold rolling,
700 to 12 equivalent to that disclosed in Japanese Patent Publication No. 213
When the hot-rolled sheet is annealed at 00 ° C., as shown in FIG. 1 (a), a texture of {100} <001> orientation in which the <001> axis is well oriented in the cross cold rolling direction is obtained. If the hot-rolled sheet annealing was not performed, the <011> axis was well oriented in the cross cold rolling direction shown in FIG. 1 (b) {100} <011>.
Is obtained. The orientation close to {100} <011> is cold rolled and further increased by annealing {100} <011>
In order to utilize the phenomenon of accumulating in the orientation, it can be said that a process in which hot rolled sheet annealing is not performed is suitable from the viewpoint of simplifying cold rolling.

In order to further stabilize the secondary recrystallization, the primary recrystallization
Nitriding of steel sheet after completion of crystallization but before the start of secondary recrystallization
It is also possible. This nitriding method is the final annealing atmosphere.
N _Two, NH_ThreeSuch as mixing a nitriding gas such as
Nitriding ability of ferromanganese nitride etc. as an annealing separator during final annealing
Method with the addition of a substance with the
NH in descending_ThreeIn an atmosphere containing a nitriding gas such as
Any method may be used.

By the above process, a bidirectional silicon steel sheet having a relatively high accumulation of <110> axes in two orthogonal directions can be obtained. Next, the steel sheet is rolled in one of the two directions described above. The rolling at this time is desirably performed cold in view of the simplicity of the process, but when the cold rolling is difficult due to a large amount of Si components, it is possible to perform the rolling at a warm temperature up to about 300 ° C. The rolling reduction is not particularly limited, but in order to obtain a sufficient effect of accumulation in the {100} <011> orientation, it is preferable to perform rolling at a rolling ratio of 30% or more, preferably 50% or more.

The conditions of the annealing performed after the rolling are not particularly limited, but annealing at a temperature of 600 ° C. or more, preferably 800 ° C. or more, sufficient to release the strain due to the rolling may be performed. By processing through the above steps,
It has been found that a bidirectional electrical steel sheet having a very excellent orientation can be obtained in which the <001> axis is well oriented in the direction of the rolling direction and 45 °.

[0020]

EXAMPLES (Example 1) Si: 3.4%, C: 0.050%, Al: 0.
A silicon steel slab containing 028% and N: 0.0070%, the balance being Fe and unavoidable impurities was heated to 1150 ° C and hot rolled to a thickness of 2.5 mm. The obtained hot-rolled sheet was cold-rolled to a thickness of 1.3 mm in the same direction as the hot-rolling, and cold-rolled to a thickness of 0.6 mm in a direction perpendicular to the cold-rolling direction. This cold-rolled sheet was annealed in wet hydrogen at 820 ° C. for 7 minutes to perform both decarburization and primary recrystallization. After applying an annealing separator mainly composed of MgO, the sheet was annealed at 1200 ° C. for 20 hours. The atmosphere at the time of this annealing is N ₂ :
25%, H ₂ : 75%, H ₂ : 10 when soaked at 1200 ° C.
It was 0%. The magnetic flux densities at an exciting force of 800 A / m in two directions at 45 ° from the hot rolling direction in the sheet surface of the bidirectional silicon steel sheet obtained by the above process were 1.
82T and 1.82T.

The material is cold-rolled in the hot rolling direction to obtain 0.48 mm, 0.42 mm, 0.36 mm, 0.30 mm,
The plate thicknesses were 0.24 mm and 0.18 mm. 9
Annealing was performed at 00 ° C. for 3 hours, and magnetic measurements were performed in two directions at 45 ° from the hot rolling direction in the plate surface. Table 1 shows the results.

[0022]

[Table 1]

FIG. 2 shows the directions of hot rolling and cold rolling and the direction of magnetic measurement. (Example 2) Si: 3.0%, C: 0.060%, Al: 0.
A silicon steel slab containing 025% and N: 0.0080%, the balance being Fe and unavoidable impurities was heated to 1150 ° C and hot rolled to a thickness of 2.0 mm. The obtained hot rolled sheet was cold rolled to a thickness of 0.9 mm in the same direction as the hot rolled sheet, and cold rolled to a thickness of 0.45 mm in a direction perpendicular to the cold rolling direction.
The cold-rolled sheet is annealed in wet hydrogen at 820 ° C. for 6 minutes to perform both decarburization and primary recrystallization, and then is nitrided at 800 ° C. for 50 seconds in an atmosphere containing NH _3, and is mainly made of MgO. After applying the annealing separating agent, annealing was performed at 1200 ° C. for 20 hours. The atmosphere during the annealing was N ₂ : 10% when the temperature was raised to 1200 ° C., H ₂ : 90%, and H ₂ : 100% when the temperature was soaked at 1200 ° C. 0.4mm obtained in this way
Table 2A shows the measured values of the magnetic flux density in two directions at 45 ° from the hot rolling direction in the plane of the thick silicon steel sheet. This silicon steel sheet was cold rolled in a direction perpendicular to the hot rolling direction to a thickness of 0.2 mm. Thereafter, annealing was performed at 900 ° C. for 2 hours in an H ₂ atmosphere.
The magnetic flux density after annealing is shown in Table 2B. It can be seen that the magnetic permeability is improved by this process.

[0024]

[Table 2]

Example 3 Si: 3.1%, C: 0.079%, Al: 0.1% by weight
026%, N: 0.0080%, Mn: 0.065,
S: A silicon steel slab containing 0.023%, the balance being Fe and unavoidable impurities, was heated to 1350 ° C. and 2.3 mm
Hot rolled to thickness. The obtained hot-rolled sheet was cold-rolled to a thickness of 1.2 mm in the hot-rolling direction.
Cold rolling was performed to a thickness of 7 mm. This cold rolled sheet is placed in wet hydrogen for 8 hours.
Annealing combined with decarburization and primary recrystallization at 70 ° C. for 8 minutes is performed, and after applying an annealing separator mainly composed of MgO, 1200
Annealing was performed at 20 ° C. for 20 hours. The atmosphere during this annealing is
When the temperature was raised to 1200 ° C., N ₂ : 25%, H ₂ : 75%,
H ₂ : 100% at 1200 ° C. The measured value of the magnetic flux density in the direction of 45 ° from the hot rolling direction in the plane of the 0.7 mm-thick silicon steel sheet thus obtained is shown in Table 3A. This silicon steel sheet was cold-rolled in the hot rolling direction to a thickness of 0.3 mm.
Thereafter, annealing at 850 ° C. for 4 hours was performed in an H ₂ atmosphere. The magnetic flux density after annealing is shown in Table 3B. It can be seen that the magnetic permeability is improved by this process.

[0026]

[Table 3]

[0027]

According to the present invention, {100} <indicates a relatively high directionality obtained by using cross cold rolling and secondary recrystallization.
011> A bidirectional silicon steel sheet having a higher degree of orientation integration can be obtained by rolling and annealing using a texture material as a starting material.

[Brief description of the drawings]

FIG. 1 (a) is a graph showing a value of # 10 in the case of performing hot-rolled sheet annealing
FIG. 4B is a diagram showing a 0 ° pole figure, and FIG. 4B is a diagram showing a {100} pole figure when hot-rolled sheet annealing is not performed.

FIG. 2 is a diagram showing a hot rolling direction, a cold rolling direction, and a direction of magnetic measurement.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-B 33-7952 (JP, B1) JP-B 38-16212 (JP, B1) JP-B 35-2657 (JP, B1) (58) Field (Int.Cl. ⁷ , DB name) C21D 8/12 C22C 38/00 303 C22C 38/06

Claims (1)

(57) [Claims] 1. Si: 1.8-6.8% by weight, A
l: 0.01 to 0.05%, N: 0.001 to 0.01
A silicon steel slab containing 2%, the balance being Fe and unavoidable impurities, is hot-rolled, cold-rolled 40 to 80% in the hot rolling direction, and then cold-rolled 30 to 70% in a direction perpendicular to the direction. , 7
After short-time annealing at 50 to 1000 ° C, 900 to 1300 ° C
In the method for producing a bidirectional silicon steel sheet subjected to finish annealing of the above, characterized in that after the finish annealing, cold rolling is performed in the same direction or a direction perpendicular to the hot rolling, and then annealing is performed. 011>.