JP4271308B2 - Steel sheet for magnetic shield and manufacturing method thereof - Google Patents

Description

【００３６】
以上の要領で得られた供試材について透磁率（μ0.35）、残留磁束密度、保磁力および非履歴透磁率を評価した。これらの性能評価は、リング状試験片に励磁コイル、検出コイルおよび直流バイアス磁界用のコイルを巻いて、非履歴透磁率、0.35 Oeにおける透磁率（μ0.35）、最大磁化50 Oeのときの残留磁束密度、保磁力を測定して行った。なお、非履歴透磁率測定方法を詳細に説明する。
【００３７】
非履歴透磁率測定方法
1）1次コイル1に減衰する交流電流を流して試験片を完全消磁する。
【００３８】
2）3次コイル3に直流電流を流して0.35 Oeの直流バイアス磁界を発生させた状態で、再度1次コイル1に減衰する交流電流を流して試験片を消磁する。
【００３９】
3）一次コイル1に電流を流して試験片を励磁し、発生した磁束を2次コイル2で検出してB−H曲線を測定する。
【００４０】
4）B−H曲線より非履歴透磁率を算出する。
板厚、調質圧延率、磁気特性、これらの評価結果を併せて表2に示す。
【００４１】
【表２】

【００４２】
表2に示すように、本発明例では、非履歴透磁率が7500以上であり、保持力も5.5 Oe以下となり、消磁後の磁気シールド性は十分であった。
【００４３】
一方、調質圧延率が1.5％を超える比較例では、非履歴透磁率が7500未満となり、磁気シールド性が不十分であった。また、C量が0.15％を超えて過剰に添加された比較例では、保磁力が大きく、消磁特性が劣化していた。
【００４４】
【発明の効果】
以上述べたように、本発明によれば高い非履歴透磁率を有し、またはさらに保持力が優れ、消磁後の磁気シールド性に優れた鋼板を得ることができる。
【００４５】
さらに、本発明による鋼板をカラー陰極線管の磁気シールドとして用いることによって、消磁後、充分な磁気シールド性が確保され、さらに地磁気ドリフトによる色ずれが抑制される。よって、高精細な画像を得るために有効な磁気シールド用鋼板が提供される。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel plate that is a material of a magnetic shield component that is installed inside or outside a color cathode ray tube so as to cover from the side with respect to the electron beam passing direction, that is, a steel plate for magnetic shielding of a color cathode ray tube.
[0002]
[Prior art]
The basic structure of a color cathode ray tube is composed of an electron gun that emits an electron beam and a fluorescent screen that forms an image by emitting light by electron beam irradiation. The electron beam is deflected by the influence of geomagnetism, and as a result, color shift occurs in the image. As a means for preventing the deflection, an internal magnetic shield (also referred to as an inner shield or an inner magnetic shield) is generally installed. Yes. An external magnetic shield (also referred to as an outer shield or an outer magnetic shield) may be installed outside the color cathode ray tube. In the present invention, these inner magnetic shield and outer magnetic shield are collectively referred to as a magnetic shield.
[0003]
In recent years, consumer TVs have become larger and wider, and the distance traveled by the electron beam and the scanning distance have increased, making it more susceptible to geomagnetism. That is, the deviation (referred to as geomagnetic drift) of the arrival point of the electron beam deflected by geomagnetism from the point where it originally should be reached is larger than before. In addition, since a cathode ray tube for a personal computer requires a higher-definition still image, color shift due to geomagnetic drift must be suppressed as much as possible.
[0004]
Under such circumstances, conventionally, the characteristics of the steel sheet used for the magnetic shield may be evaluated by using the permeability, coercive force, and residual magnetic flux density as an index in a low magnetic field that is almost equivalent to geomagnetism. There were many.
[0005]
As a method for improving the properties of a steel sheet for magnetic shielding, Japanese Patent Laid-Open No. 3-61330 discloses a technique for improving magnetic properties by using a steel having a specific composition and setting the ferrite crystal grain size number to 3.0 or less. As magnetic properties required for a cold-rolled steel sheet for shielding, for example, magnetic permeability ≧ 750 G / Oe and coercive force ≦ 1.25 Oe are described.
[0006]
Japanese Patent Application Laid-Open No. 5-41177 discloses a technique for forming an internal magnetic shield body using a magnetic material having a residual magnetic flux density of 8 kG or more.
[0007]
Japanese Patent Application Laid-Open No. 10-168551 discloses a magnetic shield material having a coercive force of 3 Oe or more and a residual magnetic flux density of 9 kG or more using a steel having a specific composition with a fine product crystal grain size, and a manufacturing method thereof. ing.
[0008]
Also, in the IEICE Transactions, Vol.J79-C-II No.6, p311-319, '96 .6, the relationship between non-historical permeability and magnetic shield property is improved to improve the magnetic shield property. It is stated.
[0009]
[Problems to be solved by the invention]
However, the magnetic shield applied to an actual color cathode-ray tube in any of the technology described in Japanese Patent Laid-Open No. 3-61330, the technology described in Japanese Patent Laid-Open No. 5-41177, and the technology described in Japanese Patent Laid-Open No. 10-168551. Steel plates are generally demagnetized in the geomagnetism, and although the magnetic properties of the steel plate change due to geomagnetization demagnetization, no consideration is given to the effects of demagnetization, so the magnetic shielding properties are insufficient. There was a problem that there was.
[0010]
In the IEICE Transactions, Vol.J79-C-II No.6, p311-319, '96 .6, the relationship between the above-mentioned non-historical permeability and magnetic shielding performance has been studied. Detailed investigations such as whether or not has a high non-history permeability have not been clarified.
[0011]
As described above, none of the technologies can cope with image deterioration due to color shift accompanying the recent increase in size and widening of consumer TVs. Further, color misregistration with respect to a cathode ray tube for a personal computer has not been suppressed.
[0012]
For these reasons, there is a strong demand for magnetic shielding steel plates having higher performance magnetic shielding properties.
[0013]
The present invention has been made to solve such problems, and has a high non-history permeability and is effective for obtaining a high-definition image by suppressing color shift due to geomagnetic drift. It aims at providing a steel plate and its manufacturing method.
[0014]
[Means for Solving the Problems]
The aforementioned problems are solved by the first to sixth inventions described below.
[0015]
1st invention is weight%, C: 0.005-0.15 %, Si: 0.01-0.02%, Mn: 0.14-0.95%, P: 0.008-0 074%, S: 0.006 to 0.013%, sol. Al: 0.033-0.055%, N: 0.0018-0.0043%, Cr: 0.029-0.046% is contained, the balance is Fe and inevitable impurities, and the plate thickness: 0.05 mm As mentioned above, it is a steel plate for 0.5 mm or less, and is a steel plate for magnetic shields characterized by non-history permeability being 7500 or more.
[0016]
2nd invention is a steel plate for magnetic shields as described in 1st invention characterized by containing B: 0.0003% or more and 0.01% or less further by weight%.
[0017]
The third invention further weight%, Ti, Nb, in the first invention or second invention, characterized in that it contains 0.08% or less in total of one or two or more of the V It is a steel plate for magnetic shielding as described.
[0018]
A fourth invention is the steel sheet for magnetic shielding according to any one of the first invention to the third invention, characterized by having a Cr plating layer and / or a Ni plating layer on the surface of the steel plate.
[0019]
A fifth invention is the steel sheet for magnetic shielding according to any one of the first invention to the fourth invention, wherein the coercive force is 5.5 Oe or less.
[0020]
In a sixth aspect of the invention, the steel sheet slab having the component composition according to any one of the first to third aspects is subjected to hot rolling, cold rolling, continuous annealing, and then rolling of 1.5% or less It is the manufacturing method of the steel plate for magnetic shields characterized by performing temper rolling at a rate.
[0021]
In addition, in this specification, all% which shows the component of steel is weight%.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described.
[0023]
In general, a color cathode ray tube employs a method of demagnetizing by applying an AC current to a degaussing coil wound outside the cathode ray tube when the power is turned on. For this reason, the magnetism shield inside the cathode ray tube is demagnetized in the geomagnetism, so that a higher level of magnetization than the magnetization for the geomagnetism remains. Due to this phenomenon, the magnetic shield has a higher performance shield characteristic than a completely demagnetized state. Therefore, as described in IEICE Transactions, Vol.J79-C-II No.6, p311-319, '96 .6, steel plates suitable for magnetic shield applications are It is considered that the steel sheet has a high “non-history permeability” obtained by dividing the residual magnetization by the geomagnetism. Therefore, the present inventors investigated the non-historical permeability in a DC bias magnetic field of 0.35 Oe for steel plates having various components based on the above findings, and examined steel plates that were excellent for use as magnetic shields.
[0024]
as a result,
(1) Conventionally, an ultra-low carbon steel plate having a relatively high permeability (hereinafter referred to as μ0.35) in a low magnetic field (for example, 0.35 Oe), which is one of evaluation indexes, is often used as a magnetic shield. However, the ultra-low carbon steel plate with high μ0.35 does not necessarily have high non-history permeability. (2) Steel plate with relatively large C content (C content: 0.005〜 0.2%) High non-history permeability can be obtained. (3) When using a steel sheet as a magnetic shield, if the non-history permeability is 7500 or more, the color misregistration is at a level that is practically acceptable. (4) Increasing the amount of C increases the coercive force, and depending on the demagnetization method (magnetization current magnitude, demagnetization amplitude magnitude, etc.), the demagnetization becomes insufficient, and the steel sheet with sufficiently high non-history permeability However, the magnetization after demagnetization becomes insufficient, and color shift can be suppressed. It found that in some cases have.
[0025]
The present inventors have further studied the above findings and have reached the present invention. Hereinafter, the reasons for limitation of the present invention will be described.
First, the reason for limiting the steel components will be described.
[0026]
C: The content regulation is the most important element in the present invention. In general, in order to lower μ0.35, it is considered a harmful element in the steel sheet for magnetic shielding. However, as described above, as a result of the study by the present inventors, it has been clarified that C does not have a great adverse effect on the non-history permeability. However, when the amount of C is excessively large, the coercive force is increased, which is not preferable because demagnetization conditions sufficient to exhibit non-historical permeability are restricted. From the above, the upper limit is made 0.15%. More preferably, it is 0.06% or less. In particular, when considering other properties such as after hot rolling, or subjected to decarburization annealing after cold rolling, it is also possible to the C amount is less than 0.0005%, in the present invention As mentioned above, it is made 0.005% or more which is a range that has hardly been used conventionally.
[0027]
B: The content regulation is an important element in the present invention. It is an important element that can increase the non-history permeability, and its effect can be obtained by adding 0.0003% or more. When it is added in excess of 0.01%, not only the effect of improving the non-historic permeability is saturated, but also problems such as an increase in recrystallization temperature and excessive hardening of the steel sheet occur. Accordingly, the content is preferably 0.0003% or more and 0.01% or less.
[0028]
Ti, Nb, V: Important elements in the present invention. These elements are all carbonitride-forming elements, and are added when aging is particularly problematic in order to suppress stretcher strain. If excessively added, problems such as an increase in the recrystallization temperature and excessive hardening of the steel sheet occur. Therefore, it is preferable that one or two or more of them be 0.08% or less in total. In order to obtain a steel sheet having a particularly high non-history permeability, it is desirable to add it in combination with B.
[0029]
Next, the plate thickness will be described.
The lower limit of the plate thickness as a magnetic shield steel plate is that if it is too thin, the magnetic shield properties will be insufficient even for a steel plate with high non-historical permeability, and rigidity as a magnetic shield component will not be obtained. 0.05mm or more. In order to improve the magnetic shielding properties, it is desirable that the plate thickness is large. However, with the recent trend toward larger and wider color televisions, it is desired to reduce the weight of the television set, so the upper limit is set to 0.5 mm.
[0030]
Next, plating will be described.
It is desirable to have a Cr plating layer and / or a Ni plating layer from the viewpoint of preventing rust. These platings may be used in a single layer or in multiple layers, and the surface on which the plating layer is formed may be one surface or both surfaces of the steel sheet. By forming the plating layer, it is effective to suppress the generation of rust on the steel sheet and to suppress the generation of gas from the steel sheet when incorporated in the cathode ray tube. The amount of adhesion is not particularly limited, and an amount of adhesion that can substantially cover the surface of the steel sheet is appropriately selected. Further, the steel plate surface may be coated by partially applying Ni plating and then performing chromate treatment.
[0031]
Next, the reason for limiting the holding force will be described.
If the coercive force becomes excessively large, the demagnetizing current value and demagnetizing amplitude necessary to exhibit sufficient magnetic shielding properties are increased, and the demagnetizing method may be limited. Is preferred. More preferably, it is 3.0 Oe or less.
[0032]
Next, a manufacturing method will be described.
Steel containing components within the scope of the present invention is melted, continuously cast, and hot-rolled in accordance with a conventional method. In the hot rolling, the continuously cast slab may be rolled directly or slightly, or the slab once cooled can be reheated and rolled. The hot-rolled steel sheet is pickled, cold-rolled and recrystallized according to a conventional method. Next, temper rolling is performed as necessary. Here, in order to ensure the non-history magnetization characteristics, the temper rolling ratio should be as small as possible, and the upper limit is 1.5%. When there is no particular problem with the shape and aging of the steel sheet, it is desirable to set it to 0.5% or less, and more preferably, no temper rolling is performed. Moreover, you may perform a decarburization annealing in the middle process as needed, and can also serve as the recrystallization annealing after a decarburization annealing and cold rolling. Furthermore, Ni or Cr is plated on the surface as necessary.
[0033]
【Example】
After melting the test steel of Table 1, it was hot-rolled to a thickness of 1.8 mm, pickled, and cold-rolled at a cold rolling rate of 83 to 94% to a thickness of 0.1 to 0.3 mm. Next, recrystallization annealing was performed at a temperature higher than the recrystallization temperature and lower than the transformation point, and Cr plating was performed on the both surfaces of the steel subjected to temper rolling of 0.5 to 2.0% as it was to obtain a test material.
[0034]
In the Cr plating, the lower layer was a metal Cr layer with an adhesion amount of 95 to 120 mg / m ² , and the upper layer was a hydrated oxide Cr layer with an adhesion amount (in terms of metal Cr) of 12 to 20 mg / m ² .
[0035]
[Table 1]

[0036]
The specimens obtained as described above were evaluated for permeability (μ0.35), residual magnetic flux density, coercive force, and non-historical permeability. In these performance evaluations, an excitation coil, a detection coil, and a DC bias magnetic field coil are wound around a ring-shaped test piece, and a non-history permeability, a permeability at 0.35 Oe (μ0.35), and a maximum magnetization of 50 Oe The measurement was performed by measuring the residual magnetic flux density and the coercive force. The non-history permeability measurement method will be described in detail.
[0037]
Non-history permeability measurement method
1) Fully degauss the specimen by passing an alternating current that attenuates through the primary coil 1.
[0038]
2) With a DC current applied to the tertiary coil 3 to generate a DC bias magnetic field of 0.35 Oe, a decaying AC current is applied to the primary coil 1 again to demagnetize the specimen.
[0039]
3) Pass a current through the primary coil 1 to excite the test piece, detect the generated magnetic flux with the secondary coil 2, and measure the BH curve.
[0040]
4) Calculate the non-history permeability from the BH curve.
Table 2 shows the sheet thickness, temper rolling ratio, magnetic properties, and the evaluation results.
[0041]
[Table 2]

[0042]
As shown in Table 2, in the examples of the present invention, the non-history permeability was 7500 or more, the coercive force was 5.5 Oe or less, and the magnetic shielding property after demagnetization was sufficient.
[0043]
On the other hand, in the comparative example in which the temper rolling ratio exceeds 1.5%, the non-historical permeability is less than 7500, and the magnetic shielding properties are insufficient. Further, in the comparative example in which the C amount exceeded 0.15% and was added excessively, the coercive force was large and the demagnetization characteristics were deteriorated.
[0044]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain a steel sheet having a high non-historic permeability, or having excellent holding power and excellent magnetic shielding properties after demagnetization.
[0045]
Furthermore, by using the steel plate according to the present invention as a magnetic shield for a color cathode ray tube, a sufficient magnetic shielding property is ensured after demagnetization, and color shift due to geomagnetic drift is suppressed. Therefore, a steel plate for magnetic shielding effective for obtaining a high-definition image is provided.

Claims (6)

By weight%, C: 0.005 to 0.15%, Si: 0.01 to 0.02%, Mn: 0.14 to 0.95%, P: 0.008 to 0.074%, S: 0.006 to 0.013%, sol. Al: 0.033-0.055%, N: 0.0018-0.0043%, Cr: 0.029-0.046% is contained, the balance is Fe and unavoidable impurities , and plate thickness: 0.05 mm As described above, a steel sheet for magnetic shielding, which is a steel sheet of 0.5 mm or less and has a non-historical permeability of 7500 or more. The steel sheet for magnetic shielding according to claim 1, further comprising B: 0.0003% to 0.01% by weight. The steel sheet for magnetic shielding according to claim 1 or 2, further comprising 0.08% or less of Ti, Nb, and V in total by weight. The steel plate for magnetic shielding according to any one of claims 1 to 3 , further comprising a Cr plating layer and / or a Ni plating layer on a surface of the steel plate. The steel sheet for magnetic shielding according to any one of claims 1 to 4, wherein the coercive force is 5.5 Oe or less. Applying hot rolling, cold rolling, and continuous annealing to the steel sheet slab having the component composition according to any one of claims 1 to 3 , and then performing temper rolling at a rolling rate of 1.5% or less. The manufacturing method of the steel plate for magnetic shields characterized by these.