JP3968964B2 - Steel plate for heat shrink band - Google Patents

Description

【００４９】
得られた各鋼板の機械特性及び磁気特性を表２に示す。
ここで、機械特性（ＹＰＥＬ）の測定はＪＩＳ５号引張試験片にて行い、磁気測定は２５ｃｍエプスタイン試験片を用いて行った。なお、磁気特性は２３．９Ａ／ｍまで磁化したときの透磁率で評価した。
【００５０】
【表２】

【００５１】
表２より、鋼板成分を本発明範囲に制御した本発明例では、良好な磁気特性および高い強度を有する鋼板が得られていることがわかる。一方、比較例では、強度が劣っているかもしくは透磁率が低いことがわかる。
【００５２】
【発明の効果】
以上述べたように、本発明によれば、磁気特性と強度とのバランスに優れたＨＳバンド用鋼板を得ることができる。
【００５３】
また、本発明は、結晶粒の粗大化等の手段を用いない為、透磁率を向上させてもほとんど強度低下を伴わないので、強度レベルを維持しつつ透磁率の向上を図ることができる。
【図面の簡単な説明】
【図１】酸素含有量と比透磁率の関係を示すグラフ。
【図２】Ｓｂ含有量と比透磁率の関係を示すグラフ。
【図３】Ｂ含有量、Ｂ／Ｎと比透磁率の関係を示すグラフ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel plate for a heat shrink band that tightens around the panel of a color cathode ray tube.
[0002]
[Prior art]
In a color cathode ray tube (hereinafter referred to as CRT), since the inside of the tube is in a high vacuum state of about 1.0 × 10 ⁻⁷ Torr, processing such as prevention of deformation of the panel surface and prevention of internal explosion of the tube is required. Yes. As such a treatment, a heat shrink band (hereinafter referred to as an HS band) made of a steel plate formed into a band shape is heated and expanded at a temperature of about 400 ° C. to 600 ° C. for several seconds to several tens of seconds to form a CRT glass panel. A method of correcting the deformation of the panel surface by a so-called shrink fitting process in which tension is applied by fitting, cooling / shrinking may be mentioned.
[0003]
Conventionally, HS band materials used for the above-mentioned shrink-fitting treatment have been required to be lightweight and have a predetermined strength and ductility. As HS band materials, cold plated plates with a thickness of 0.8 to 2 mm are used. A rolled steel sheet was used. However, after that, it was found that by giving the HS band material the shielding effect of the external magnetic field such as geomagnetism, the color shift caused by the shift of the landing spot of the electron beam can be greatly reduced, and the magnetic shielding property is a new steel plate performance. It is attracting attention.
[0004]
As a method for imparting high magnetic shielding properties while giving high strength to the HS band material as described above, for example, in Japanese Patent Application Laid-Open No. 11-86755, Si is included in a solid solution strengthening by containing 1 to 2%. A method for improving the magnetic permeability at the geomagnetic level is disclosed in JP-A-11-158549. The inclusion composition of Si-containing steel is optimized to improve the coercive force, and the crystal grain size is optimized. A method for increasing the strength is disclosed.
[0005]
[Problems to be solved by the invention]
Recently, further weight reduction of TV picture tubes has been aimed at, and the demand for thinner HS band materials is becoming stronger. On the other hand, the demand for magnetic shielding (that is, magnetic properties such as high permeability) has become stricter with the increase in screen size and flatness of televisions and the increase in definition of computer monitors. Has been. As described above, the HS band material is strongly demanded to further increase the strength and improve the magnetic characteristics (high permeability).
[0006]
However, in the above prior art, as a method for improving the strength and the magnetic permeability, a method of containing a large amount of elements such as Si, Mn, and P and a method of optimizing the crystal grain size are employed. In the method described in Japanese Patent No. -86755, it is difficult to further increase the content of Si, Mn, P and the like from the viewpoint of weldability and manufacturing cost, and it can be said that higher strength and higher permeability are difficult. Further, in the method described in JP-A No. 11-158549, although the strength can be increased by making fine particles, the magnetic permeability is lowered at the same time, so that the magnetic permeability is insufficient if an attempt is made to achieve a desired strength level. It becomes.
[0007]
As described above, in the prior art, a steel sheet having excellent strength and magnetic properties to meet recent needs has not been obtained.
[0008]
This invention is made | formed in view of such a situation, and it aims at providing the steel plate excellent in the balance of an intensity | strength and magnetic permeability.
[0009]
[Means for Solving the Problems]
The inventors of the present invention have made extensive studies in order to increase the strength and permeability of the HS band material while paying attention to B that easily forms coarse precipitates. As a result, the following knowledge was obtained.
[0010]
{Circle around (1)} B, which is an element effective in improving the magnetic properties, has a strong affinity for O, so it is easy to produce B ₂ O ₅ that is a fine inclusion during casting.
[0011]
(2) When the slab is heated, oxidation of B proceeds on the surface layer, and a B depleted layer is likely to occur.
[0012]
(3) Further, since B has a strong affinity for N, surface layer nitriding is likely to occur during slab heating or annealing, and it is easy to bond with N to form coarse precipitates.
[0013]
{Circle around (4)} When the B ₂ O ₅ and B depletion layers and surface nitridation as described above occur, the effect of B addition is not fully utilized.
[0014]
(5) In order to prevent the formation of B ₂ O ₅ and B depletion layers and surface nitriding and to fully utilize the effect of B addition, the O content during casting is sufficiently reduced to a certain amount or less, and Sb is reduced. It is effective to add an appropriate amount in combination with B.
[0015]
This invention is made | formed based on this knowledge, and has the following structures.
[1] In mass%, C: 0.005% or less, Si: 0.5 to 4%, Mn: 2% or less, sol. Al: 0.2% or less, S: 0.04% or less, P: 0.2% or less, N: 0.01% or less, B: 0.0003 to 0.004%, T.P. O. : 0.005% or less, Sb: 0.002 to 0.1%, a steel sheet for heat shrink band made of the remaining Fe and inevitable impurities .
[0016]
[2] A steel sheet for heat shrink band according to [1], wherein the B content and the N content satisfy B / N: 0.2 to 1.
[0017]
In addition, in this specification, all% which shows the component of steel is mass%.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the details of the present invention will be described together with the reasons for limitation.
First, various B-containing steels were subjected to chemical analysis of the extraction residue, observation with a transmission electron microscope, and the like, and a detailed investigation of precipitates and inclusions was performed. As a result, in the B-containing steel, B ₂ O ₅ , which is an oxide, was generated in addition to the nitride, and a tendency for the permeability to be inferior in steel having a relatively large amount of oxide generation was recognized. As a result of observation with an electron microscope, the size of the oxide was found to be relatively fine, and it was estimated that the oxide itself had an adverse effect on the magnetic permeability. Since B has a strong affinity for oxygen, it is considered that B ₂ O _5, which is an oxide, is formed if the dissolved oxygen is not sufficiently reduced during casting of molten steel.
[0019]
Then, the oxygen content which influences a magnetic characteristic was investigated for the purpose of the magnetic characteristic improvement of B containing steel.
[0020]
C: 0.002%, Si: 1.2%, Mn: 1%, P: 0.07%, S: 0.004%, sol. Al: tr. Or 0.01%, N: 0.002%, B: 0.0016%. O. The steel was changed from 0.001 to 0.01%. Here, T.W. O. The amount (oxygen content) is adjusted by adjusting the degassing time after adding Si or Al, and B is consumed as an oxide at the stage before casting when added at a stage where the dissolved oxygen amount is high. In order to prevent this, Si and Al were added, and then added immediately before casting the molten steel. Subsequently, hot rolling and cold rolling to a sheet thickness of 1.2 mm were performed, and the crystal grain size was adjusted by annealing at 680 to 730 ° C. to obtain a test material having a strength level of YP = 330 to 340 MPa. .
[0021]
A 25 cm Epstein sample was taken from the obtained test material, and the magnetic properties were measured. The magnetic properties (permeability) were evaluated by the relative permeability when magnetized to 23.9 A / m (0.3 alested). In addition, the oxygen content was confirmed in advance that there was almost no difference between the hot-rolled sheet and the final annealed sheet. Here, the results obtained by examining a sample collected from the final annealed sheet having a thickness of 1.2 mm were used. It was.
[0022]
FIG. 1 shows the relationship between the oxygen content (TO) and the relative permeability of the test material thus obtained. In FIG. 1, sol. Al: tr. The magnetic properties of the steels of No. Al: Magnetic properties of 0.01% steel are indicated by ●.
[0023]
From FIG. 1, the relative permeability of B-containing steel is closely related to the oxygen content of the steel. Al: tr. Test material (circle in the figure), sol. Al: 0.01% of the test material (● in the figure) O. It has been found that a high relative magnetic permeability can be obtained when the content is reduced to 0.005% or less. T. O. When the precipitates and inclusions were investigated for a steel sheet with 0.005% or less, B was almost completely present as a nitride, and the oxide was sol. Al: tr. For steel, SiO ₂ , sol. It was confirmed that Al: 0.01% steel is mainly composed of Al ₂ O ₃ .
[0024]
From the above results, the oxygen content (TO) is made 0.005% or less.
Next, the effect of Sb addition in B-containing steel was investigated.
In the steel of the present invention, the C content is set to 0.005% or less for the purpose of improving the magnetic permeability. In such a so-called ultra-low carbon steel, oxidation of elements other than C in the surface layer is likely to occur during heating or annealing of the slab. The cause of this is not necessarily clear, but when C is sufficiently present, C is preferentially oxidized, but if the C content is low, the effect cannot be obtained sufficiently, and oxidation of other elements occurs. it is conceivable that. Since the steel according to the present invention uses B-containing steel, it is considered that the oxidation reaction of B on the surface layer is likely to proceed.
[0025]
In addition, since B has a strong affinity for N, it is considered that it easily binds to nitrogen existing as a furnace atmosphere component in the surface layer during slab heating or annealing, and nitriding is likely to occur in the steel sheet surface layer.
[0026]
Therefore, for the purpose of preventing oxidation and nitridation of B at the surface layer, the combined addition of Sb to the B-containing steel was examined. C: 0.002%, Si: 1.2%, Mn: 1%, P: 0.07%, S: 0.004%, sol. Al: 0.02%, N: 0.002%, B: tr. Or 0.0015%, T.I. O. : 0.002%, Sb is tr. The steel changed to ˜0.2% was melted and subjected to hot rolling, cold rolling and annealing under the same conditions as in FIG.
[0027]
Next, a 25 cm Epstein sample was collected from the obtained test material, and the magnetic properties were measured. In addition, the measurement of a magnetic characteristic (magnetic permeability) and the measurement of oxygen content were performed by the method similar to FIG.
[0028]
FIG. 2 shows the relationship between the Sb addition amount and the relative magnetic permeability of the test material thus obtained. In FIG. 2, B: tr. The relative magnetic permeability of steel No. is indicated by ●, and the relative permeability of B: 0.0015% steel (B-containing steel) is indicated by ○.
[0029]
From FIG. 2, it can be seen that the B-containing steel (◯ in the figure) further improves the relative permeability by containing Sb in a range of 0.002 to 0.1%.
[0030]
B-containing steel Sb: tr. When B and N were subjected to chemical analysis in the depth direction from the surface layer of the Sb: 0.02% material and Sb: tr. In the material, it was found that the B content decreased in the region from the surface layer to a depth of about 50 μm. This is presumed that B was preferentially oxidized in the steel surface layer and the B content was reduced. Further, it was found that in the region from the surface layer to a depth of about 30 μm, the N content slightly increased compared to the inside of the steel sheet, and nitriding occurred.
[0031]
On the other hand, in the Sb: 0.02% material, both oxidation and nitridation were reduced. The Sb: 0.02% material is considered to have improved magnetic properties by preventing oxidation and nitriding on the steel surface layer.
[0032]
For the above reasons, the amount of Sb added is set to 0.002 to 0.1%.
Next, in order to further improve the magnetic characteristics, the relationship between the B content and the magnetic characteristics was investigated. C: 0.002%, Si: 1.2%, Mn: 1%, P: 0.07%, S: 0.004%, sol. Al: 0.01%, N: 0.003%, and B is tr. -0.006%, and T.I. O. And the content of Sb, T. O. : 0.006%, Sb: tr. Steel adjusted to T. O. : 0.002%, Sb: tr. Steel adjusted to T. O. : Steel adjusted to 0.002% and Sb: 0.01% were melted, hot-rolled, cold-rolled and annealed under the same conditions as in Fig. 1 to obtain test materials.
[0033]
Next, a 25 cm Epstein sample was collected from the obtained test material, and the magnetic properties were measured. In addition, the measurement of a magnetic characteristic (magnetic permeability) and the measurement of oxygen content were performed by the method similar to FIG.
[0034]
FIG. 3 shows the relationship between the B content, B / N, and relative permeability of the test material thus obtained. In FIG. O. : 0.006%, Sb: tr. The relative permeability of the steel adjusted to ▲ is T. O. : 0.002%, Sb: tr. The relative permeability of the steel containing でO. : The relative magnetic permeability of steel containing 0.002% and Sb: 0.01% is indicated by ◯.
[0035]
From FIG. O: 0.006%, Sb: tr. The steel adjusted to (▲ in the figure) has a somewhat large variation in the value of relative permeability, and has a maximum near B / N = 1.2. T. O: 0.002%, Sb: tr. In the steel adjusted to (● in the figure), the variation in relative permeability is T.V. O. : It is improved from the steel containing 0.006%, the value is also improved, and the relative magnetic permeability becomes a maximum in the vicinity of B / N = 0.9.
[0036]
On the other hand, T.W. O. : Steel adjusted to 0.002% and Sb: 0.01% (◯ in the figure), due to the combined addition of B and Sb, O: 0.002%, Sb: tr. The relative permeability is further improved than that of steel, and becomes maximum near B / N = 0.7. As described above, by adding B and Sb in combination with steel with an optimized oxygen content, the relative permeability is greatly improved, and further by setting B / N within an appropriate range, the relative permeability is further increased. Can be seen to improve.
[0037]
For the above reasons, the B content is set to a range of 0.0003 to 0.004% where an effect of improving magnetic properties is recognized. In order to further improve the magnetic characteristics, it is preferable that B and N are in the range of 0.2 to 1 in terms of B / N.
[0038]
Next, the reason for limiting other components will be described.
C: When the content exceeds 0.005%, carbide precipitates and the magnetic permeability is deteriorated. Therefore, C is 0.005% or less.
[0039]
Si: An important element that increases the strength and simultaneously improves the magnetic permeability. In order to exhibit the effect of increasing the strength and improving the magnetic permeability by adding Si, it is necessary to add 0.5% or more. On the other hand, even if Si is added in excess of 4%, the effect of improving the magnetic permeability is small, and the cost is increased. Furthermore, deterioration of weldability, embrittlement and the like are also caused. Therefore, the Si content is 0.5-4%.
[0040]
Mn: An element that has a relatively low magnetic permeability deterioration and increases the strength by solid solution strengthening. Therefore, it is desirable to add an appropriate amount of Mn in order to ensure strength. However, if added over 2%, the magnetic properties deteriorate. Accordingly, Mn is set to 2% or less.
[0041]
P: An element having a small magnetic permeability deterioration and a large solid solution strengthening ability even in a small amount. Therefore, it is an element that should be actively utilized. However, if added over 0.2%, the weldability is significantly deteriorated, so the content is made 0.2% or less.
[0042]
sol. Al: Although addition is not essential, T.I. O. It is desirable to make it contain for the purpose of reducing. However, if the content exceeds 0.2%, the effect of containing B cannot be obtained, and the cost is unnecessarily increased, so the content is made 0.2% or less. Further, it is desirable to contain 0.001% or less in order to stably make the oxide SiO ₂ or 0.005% or more in order to make Al ₂ O ₃ .
[0043]
N: An element that easily forms precipitates and deteriorates magnetic properties. Therefore, it is 0.01% or less.
[0044]
In the present invention, the effect is very small compared with Sb, but for the purpose of preventing oxidation and nitridation, for example, Sn: 0.003 to 0.15%, Cu: 0.05 to 0.2 % Or a combination of two or more of them may be added.
[0045]
Next, the manufacturing method of the steel plate for heat shrink bands of this invention is demonstrated.
In the present invention, the components specified in the present invention need only be within the scope of the present invention. To obtain the steel sheet of the present invention, for example, the molten steel blown in a converter is degassed and adjusted to a predetermined component. Subsequently, casting and hot rolling are performed. The finish annealing temperature and the coiling temperature during hot rolling need not be specified and may be normal. Moreover, although hot-rolled sheet annealing after hot rolling may be performed, it is not essential. Next, after a predetermined sheet thickness is obtained by one or more cold rollings or two or more cold rollings with intermediate annealing, final (finishing) annealing is performed.
[0046]
The HS band material may be plated from the viewpoint of corrosion resistance. The type of plating is not particularly limited. For example, Zn, Zn—Ni alloy, Zn—Al alloy, single layer plating such as Ni, Al, Sn, Cr, etc., or their reverse layer plating, or plating and ground iron It is possible to apply plating in which these are partially or wholly alloyed.
Moreover, you may form various chemical conversion treatment films on the steel plate surface or the plating surface.
[0047]
【Example】
The molten steel blown in the converter was degassed, cast into predetermined components, slab heated at 1150 ° C. × 1 hr, and then hot-rolled to a thickness of 3.2 mm. Here, the winding temperature was 680 ° C. Then, pickling was performed, followed by cold rolling to a plate thickness of 1.2 mm, followed by finish annealing at 680 ° C. to 820 ° C. × 60 sec in a 10% H ₂ -90% N ₂ atmosphere. In addition, some steel plates were subjected to skin pass rolling with an elongation of 0.5 to 1.5% after annealing.
Table 1 shows the chemical composition of the steel sheet after finish annealing.
[0048]
[Table 1]

[0049]
Table 2 shows the mechanical properties and magnetic properties of the obtained steel sheets.
Here, the measurement of mechanical properties (YPEL) was performed using a JIS No. 5 tensile test piece, and the magnetic measurement was performed using a 25 cm Epstein test piece. The magnetic characteristics were evaluated by the magnetic permeability when magnetized to 23.9 A / m.
[0050]
[Table 2]

[0051]
From Table 2, it can be seen that in the present invention example in which the steel plate components are controlled within the range of the present invention, a steel plate having good magnetic properties and high strength is obtained. On the other hand, in a comparative example, it turns out that intensity | strength is inferior or magnetic permeability is low.
[0052]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain a steel sheet for HS band excellent in balance between magnetic properties and strength.
[0053]
In addition, since the present invention does not use means such as coarsening of crystal grains, even if the magnetic permeability is improved, there is almost no decrease in strength, so that the magnetic permeability can be improved while maintaining the strength level.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between oxygen content and relative permeability.
FIG. 2 is a graph showing the relationship between Sb content and relative permeability.
FIG. 3 is a graph showing the relationship between B content, B / N, and relative permeability.

Claims (2)

mass: C: 0.005% or less, Si: 0.5-4%, Mn: 2% or less, sol. Al: 0.2% or less, S: 0.04% or less, P: 0.2% or less, N: 0.01% or less, B: 0.0003 to 0.004%, T.P. O. : 0.005% or less, Sb: 0.002 to 0.1%, a steel sheet for heat shrink band made of the remaining Fe and inevitable impurities . The steel sheet for heat shrink band according to claim 1, wherein the B amount and the N amount satisfy B / N: 0.2 to 1.

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