JPH11286726A - Steel plate for heat shrink band with less color shift and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a steel sheet for heat shrink band, small in color slippage and capable of maintaining sufficient magnetic shielding property while holding a tension of a level causing no problem in explosion-proof characteristic. SOLUTION: A steel, having a composition containing, by weight, <=0.1% C, <=0.1% Si, 0.1-1.0% Mn, <=0.02% S, <=0.08% sol. Al, and <=0.005% N, is hot rolled and successively cold rolled. The resultant steel sheet is annealed at a temp. of 650 to 850 deg.C. After annealing, the steel sheet is overaged at a temp. of 250 to 450 deg.C and then temper rolled or not temper rolled. By this method, the steel sheet for heat shrink band, minimal in color slippage, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel plate for a heat shrink band which tightens around a panel portion of a color cathode ray tube such as a television and a method for manufacturing the same, and more particularly to a steel plate for a heat shrink band with less color shift and a method for manufacturing the same. .

[0002]

2. Description of the Related Art In a color cathode ray tube, the inside of the tube is 1.0 ×.
Since it is in a high vacuum state of 10 ^-7 Torr, it is necessary to take measures to prevent deformation of the panel surface and inner explosion of the tube. From such a viewpoint, a heat shrink band made of a steel sheet formed into a band shape is used at 500 to 600 ° C.
, Heat and expand for about 60 seconds, fit into the color cathode ray tube glass panel, and apply tension by cooling and shrinking.

Further, such a heat shrink band also has a function of shielding the terrestrial magnetism as well as the internal magnetic shield, and the displacement of the landing position of the electron beam on the phosphor screen due to the terrestrial magnetism, that is, the color displacement occurs. Has the function of preventing

Conventionally, this heat shrink band includes:
Permeability at geomagnetic level (0.3 Oe) is about 200
Although mild steel is used, the magnetic shielding properties are insufficient, so that complicated steps such as adjusting the position of the phosphor screen are required for color shift due to terrestrial magnetism.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and maintains a sufficient magnetic shielding property while maintaining a level of tension that does not cause a problem in explosion-proof properties, and reduces color misregistration. An object of the present invention is to provide a heat-shrink band steel sheet and a method of manufacturing the same.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have obtained the following knowledge. (1) When the Si content of the material of the heat shrink band steel sheet is 0.1% or less, the product μ × t of the magnetic permeability μ and the sheet thickness t at 0.3 Oe, which is the external magnetic field strength at the geomagnetic level, is 40.
When the value is 0 or more, the color shift is improved. (2) In order to maintain the above magnetic permeability, the rolling reduction of the temper rolling performed after annealing at 650 ° C. or more and 850 ° C. or less and subsequent carbide precipitation treatment is 0.5% or less (no temper rolling). ). (3) Further, in order to maintain a high magnetic permeability after the shuffling treatment, it is necessary to perform the above-described carbide precipitation treatment in a temperature range of 250 to 450 ° C. (4) However, if Si is added in excess of 0.1%, the strength of the band at high temperatures increases, and as a result, the adhesion between the band and the panel decreases, and the geomagnetic drift property deteriorates.

The present invention has been completed on the basis of these findings, and is expressed in terms of% by weight: C: 0.1% or less, Si:
0.1% or less, Mn: 0.1% or more and 1.0% or less, S:
0.02% or less, sol. Al: 0.08% or less, N:
The steel containing 0.005% or less is hot-rolled, subsequently cold-rolled, and then the obtained steel sheet is heated to 650 ° C to 85 ° C.
Annealing at 0 ° C. or less, over-aging at a temperature of 250 ° C. or more and 450 ° C. or less after annealing, and then performing temper rolling at a rolling reduction of 0.5% or less or not performing temper rolling. An object of the present invention is to provide a method for producing a steel sheet for a heat shrink band with less color shift.

Further, the product μ × t of the magnetic permeability μ at 0.3 Oe after the shrink-fitting heat treatment at 0.3 Oe and the product μ × t of the plate thickness t are 400 or more, and there is little color shift. A steel sheet for a heat shrink band is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. First, the circumstances that led to the present invention will be described.

[0010] 1. 1 shows the relationship between C: 0.03%, Si: 0.01%, and Mn:
0.22%, P: 0.01%, S: 0.012%, so
l. A steel having a composition of Al: 0.02% and N: 0.002% is hot-rolled to 3.2 mm after laboratory melting, and then cold-rolled to 0.8 to 1.6 mmt, and is 700 ° C or 800 ° C. After annealing at 90 ° C. for 90 seconds and then performing an overaging treatment at 350 ° C. for 2 minutes, processing into a band of a predetermined shape without performing temper rolling, heating at 500 ° C. for 60 seconds, and then forming a 29-inch TV cathode ray tube panel This is the result of evaluation of inset and geomagnetic drift properties. Here, as a conventional material, a similar study was performed on a steel sheet having the above-described composition, which had been subjected to temper rolling of 1% after overaging treatment.

The abscissa in the figure represents the external magnetic field equivalent to the geomagnetism measured by subjecting a ring specimen taken from the annealed plate before shrink fitting to heat treatment equivalent to shrink fitting.
The product μ × t of the magnetic permeability and the plate thickness at e is shown.

Further, Bh and Bv on the vertical axis indicate the drift amount of the landing point of the electron beam. Specifically, the CRT is set to 36 with a vertical magnetic field of 0.35 Oe and a horizontal magnetic field of 0.3 Oe added to the CRT.
By rotating the electron beam by 0 °, the displacement (landing error) of the landing point of the electron beam with respect to the reference point is measured, and the value of the peak-to-peak is calculated as the horizontal drift amount Bh
And The horizontal magnetic field is set to 0 Oe, and the vertical magnetic field is set to 0 Oe.
The landing error when changing from e to 0.35 Oe was measured as the vertical drift amount Bv. The drift amount of the landing error on the vertical axis is shown as a relative value when the value of the above-described conventional material is set to 1.

FIG. 1 shows that when μ × t increases, Bh, Bv
Both tend to decrease, and the color shift due to geomagnetic
It can be seen that this is improved by increasing xt, and that the value is superior to conventional steel at 400 or more.

2. FIG. 2 shows C: 0.02%, Si: 0.02%, and Mn:
0.17%, P: 0.01%, S: 0.012%, so
l. A steel having a composition of Al: 0.03%, N: 0.002% is hot-rolled to 2.5 mm after melting in a laboratory, then cold-rolled to 1.0 mmt, and annealed at 750 ° C. for 60 seconds. After performing the overaging treatment of 400 ℃, 90 seconds,
After performing temper rolling at a rolling ratio of 0 to 2.0%, and then performing annealing at 500 ° C. for 60 seconds, which is heat treatment equivalent to shrink fitting, the rolling ratio, magnetic permeability, and sheet thickness of temper rolling are obtained. Product μ ×
This shows the relationship with t. Up to a rolling reduction of 0.5% in the temper rolling, the magnetic permeability of the material slightly decreases as the rolling reduction increases, but no remarkable change in the magnetic permeability is observed. On the other hand, it can be seen that when temper rolling exceeds 0.5%, remarkable decrease in magnetic permeability occurs.

Although the cause is not clear, according to the findings of the present inventors, when the rolling reduction of the temper rolling is extremely low up to 0.5%, the distortion due to the pressure control is caused on the surface of the steel sheet. Is applied relatively uniformly, but is introduced only very coarsely inside the steel sheet, and as a result, it is presumed that the magnetic permeability did not significantly decrease.

In this type of steel sheet, the pressure adjustment is generally performed for the purpose of preventing a surface defect called a stretcher / strain mark after working and forming. Since molding and processing are not severe, significant surface defects do not occur even if pressure is not applied. Rather, from the viewpoint of obtaining high magnetic permeability, when there is no problem in appearance, it is desirable to omit the pressure regulation.

3. Relationship between Si content in steel and geomagnetic drift FIG. 3 shows C: 0.02%, Mn: 0.15%, P: 0.0
1%, S: 0.01%, sol. Al: 0.03%,
N: 0.002%, Si: changed from 0.01 to 0.2% steel, hot rolled to 3.2 mm after laboratory melting, then cold rolled to 1.6 mmt, at 750 ° C 6
After annealing for 0 seconds, it is overaged at 400 ° C for 90 seconds, then processed into a band of a predetermined shape without temper rolling, and then heated to 500 ° C and fitted into a 29-inch TV cathode ray tube panel. And the results of a test of the geomagnetic drift property are shown.

The geomagnetic drift characteristics showed good characteristics up to a Si content of 0.1%, but tended to deteriorate when the Si content exceeded 0.1%. In general, it is expected that the magnetic permeability will improve when the amount of Si increases, so that the geomagnetic drift property is expected to be improved. Therefore, this phenomenon was examined in detail.

As a result, it was found that when the Si content was more than 0.1%, the adhesion between the panel and the band was reduced, and a gap was generated between the panel and the band. It is considered that such a gap is a factor that deteriorates the magnetic shielding property, so that the geomagnetic drift property is deteriorated.

It is not clear why the adhesion decreases when the amount of Si increases, but it is considered that since Si increases the high-temperature strength, the adhesion at shrink shrinkage decreases and gaps are formed. From the above results, the amount of Si is set to 0.1% or less.

4. Relationship between Annealing Temperature and Magnetic Permeability FIG. 4 shows C: 0.03%, Si: 0.03%, Mn:
0.20%, P: 0.01%, S: 0.007%, so
l. A steel having a composition of Al: 0.03% and N: 0.002% is hot-rolled to 2.8 mm after being melted in a laboratory, then cold-rolled to 1.0 mmt, and heated at 500 to 900 ° C for 60 hours.
After annealing for 2 seconds, an overage treatment of 400 ° C. for 90 seconds was performed, and without temper rolling, annealing was performed at 500 ° C. for 60 seconds, which is a heat treatment equivalent to shrink fitting. It shows the relationship between the product μ × t of temperature, magnetic permeability and plate thickness.

Up to an annealing temperature of 600 ° C., as the annealing temperature increases, the magnetic permeability of the material slightly increases.
No significant change in magnetic permeability is observed. On the other hand,
It can be seen that when annealing is performed in a temperature range of 850 ° C., the magnetic permeability is significantly improved. When the annealing temperature is further increased to 900 ° C., on the contrary, the magnetic permeability significantly decreases. This change in magnetic permeability corresponds to the microstructure of the steel sheet. (1) If the temperature is lower than 650 ° C., recrystallization is insufficient, so that no significant improvement in magnetic permeability is observed. Below 850 ° C,
With the recrystallization and grain growth, the magnetic permeability is improved, and (3)
If the temperature exceeds 850 ° C., transformation occurs, so that crystal grains are refined and the magnetic permeability is considered to decrease again. Therefore, the annealing temperature is desirably from 650 ° C to 850 ° C.

5. FIG. 5 shows C: 0.02%, Si: 0.03%, Mn:
0.20%, P: 0.01%, S: 0.005%, so
l. A steel having a composition of Al: 0.04% and N: 0.002% is hot-rolled to 2.8 mm after melting in a laboratory, then cold-rolled to 1.0 mmt, and after annealing at 750 ° C. for 60 seconds. After being subjected to overaging treatment at 150 to 500 ° C. for 90 seconds, without subjecting to temper rolling, annealing at 500 ° C. for 60 seconds, which is a heat treatment equivalent to shrinkage, It is a figure which shows the relationship between the overaging temperature and magnetic permeability of what was heat-processed at 150 degreeC for 100 hours for investigation.

As is evident from the figure, according to the invention, 2
When the overaging treatment is performed at a temperature of 50 ° C. or more and 450 ° C. or less, it has excellent magnetic permeability even after an acceleration test at 150 ° C. for 100 hours. On the other hand, when the temperature of the overaging treatment is out of the range of the present invention, it has been found that the magnetic permeability significantly decreases as time passes, although the magnetic permeability is high if the temperature is kept short.

As described above, by performing the overaging treatment at a temperature of 250 ° C. or more and 450 ° C. or less, excellent magnetic permeability can be obtained even after the accelerated test. This is the result obtained only by optimizing the combination of the shrink-fitting process and the overaging process specific to the heat shrink band. That is, if the overaging temperature is less than 250 ° C., solid solution C in the steel does not sufficiently precipitate even after the shuffling treatment, and although the magnetic permeability immediately after the shrinking is high, carbide is finely precipitated after the shrinking. This causes a significant decrease in magnetic permeability. On the other hand, if the overaging temperature exceeds 450 ° C., the amount of solid solution C increases, and carbide cannot be sufficiently precipitated even by the subsequent shrink fit treatment. Is degraded.
From the above results, the overaging condition was 250 ° C or more and 450 ° C or more.
℃ or lower is required.

As described above, by performing annealing after cold rolling, subsequent overaging treatment and temper rolling under the conditions specified in the present invention, the magnetic permeability μ at 0.3 Oe after heat treatment is determined.
And the product μ × t of the sheet thickness t can be 400 or more,
It is possible to obtain a heat shrink band steel sheet with less color shift.

Next, the reasons for limiting other components will be described. C: C is not preferable for the magnetic permeability, and its amount is set to 0.1% to prevent this adverse effect.

Mn: The content of Mn is 0.1% or more for improving hot ductility. On the other hand, if the amount exceeds 1.0%, the magnetic permeability deteriorates.

S: S is not preferable for both hot ductility and magnetic permeability, and is set to 0.020% or less from the viewpoint of not adversely affecting these.

Sol. Al: sol. Al deteriorates workability. In order to prevent this effect, the content is set to 0.0
8% or less.

N: Like C, N is an element unfavorable for magnetic permeability, and its content is set to 0.005% or less in order to prevent this adverse effect.

The heat shrink band may be plated from the viewpoint of corrosion resistance. Even in this case, if the characteristics before plating satisfy the range of the present invention,
A predetermined characteristic is obtained.

[0033]

EXAMPLES After melting the test steels shown in Table 1, they were reheated to 1200 ° C., and finished at a finishing temperature of 820 ° C. and a winding temperature of 680 ° C. to obtain a plate thickness of 3.
It was hot rolled to 2 mm. The obtained hot-rolled sheet is pickled, cold-rolled to a sheet thickness of 0.8 to 1.6 mm, and then 500 to 90 mm.
Annealing was performed at 0 ° C. for 90 seconds, followed by overaging at 150 to 500 ° C. for 2 minutes. These steel sheets were further heated at 500 ° C. equivalent to heat shrink for 5 seconds, air-cooled to room temperature, and then subjected to yield stress, DC magnetic properties (permeability at 0.3 Oe, and coercive force when excited to 0.5 T). )
Was measured with a ring test piece (inner diameter 33 mm, outer diameter 45 mm). The magnetic stability was evaluated at 150 ° C.
The DC magnetic properties after the heat treatment for × 100 hours were also evaluated. Further, the 700 ° C. annealed material was processed into a band having a predetermined shape, heated to 500 ° C., fitted into a 29-inch TV cathode ray tube panel, and the geomagnetic drift property was evaluated.
Table 2 shows the results. In addition, the geomagnetic drift property was represented by a relative value assuming that the geomagnetic drift amount of the test steel A of the conventional method shown in Table 2 was 1 at a pressure regulation rate of 1%.

[0034]

[Table 1]

[0035]

[Table 2]

As shown in Table 2, in the examples of the present invention in which the test steel components, the annealing temperature, the overaging treatment conditions, and the pressure regulation ratio were within the range of the present invention, μ × t ≧ 400 and the geomagnetic drift property It was confirmed that excellent characteristics were exhibited. On the other hand, in the comparative examples out of the range of the present invention, the magnetic permeability is out of an appropriate value, and a complicated process is required as a countermeasure for color misregistration.

[0037]

As described above, according to the present invention,
A steel sheet suitable for a heat shrink band having high magnetic permeability and small geomagnetic drift can be obtained. By using the steel sheet of the present invention for a heat shrink band of a cathode ray tube, a sufficient magnetic shielding property is secured, and the problem of color shift is solved.

[Brief description of the drawings]

FIG. 1 is a view showing the relationship between μ × t and geomagnetic drift.

FIG. 2 is a diagram showing a relationship between a pressure regulation rate and μ × t.

FIG. 3 is a diagram showing the relationship between the amount of Si and the geomagnetic drift property.

FIG. 4 is a diagram showing a relationship between an annealing temperature and μ × t.

FIG. 5 is a diagram showing the relationship between the overaging treatment temperature and μ × t.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshihiko Oda 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd.

Claims (2)

[Claims] C .: 0.1% or less by weight, Si:
0.1% or less, Mn: 0.1% or more and 1.0% or less, S:
0.02% or less, sol. Al: 0.08% or less, N:
The steel containing 0.005% or less is hot-rolled, subsequently cold-rolled, and then the obtained steel sheet is heated to 650 ° C to 85 ° C.
Annealing at 0 ° C. or less, over-aging at a temperature of 250 ° C. or more and 450 ° C. or less after annealing, and then performing temper rolling at a rolling reduction of 0.5% or less or not performing temper rolling. A method for producing a steel sheet for heat shrink bands with less color shift. 2. The product μ of the magnetic permeability μ and the plate thickness t at 0.3 Oe manufactured by the method of claim 1 after heat treatment.
× t is 400 or more, a steel sheet for a heat shrink band having little color shift.