JP2001254147A - Fe-Ni SERIES ALLOY SHEET FOR SHADOW MASK WITH SUPPRESSED STRIPE-LIKE UNEVENNESS AND ITS PRODUCING METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Fe-Ni series alloy sheet improved in the grade of the stripe-like unevenness. SOLUTION: This Fe-Ni series alloy sheet for a shadow mask has a composition containing 30 to 50% Ni, <=0.015% C, <=0.20% Si, <=0.5% Mn, <=0.02% Al and <=0.0040% B and the balance substantially Fe and has the accumulating degree of the (200) plane in the cross-section vertical to the rolling direction of >=40%. The alloy sheet is produced by subjecting an Fe-Ni series alloy sheet to cold rolling in such a manner that the rolling ratio directly before finish annealing is controlled to >=75%. By enlarging the ruggedness in the etching face caused by crystal orientation, optical light and dark patterns (the stripe-like unevenness) caused by microruggedness due to segregation are canceled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Fe--Ni alloy plate suitable for a shadow mask incorporated in a picture tube such as a cathode ray tube for a color television, a display for OA equipment, and a method for producing the same.

[0002]

2. Description of the Related Art A picture tube such as a cathode ray tube for a color television and a display for OA equipment incorporates a shadow mask in which a large number of electron beam passage holes are formed. The electron beam emitted from the electron gun passes through a specific electron beam passage hole, and projects a beam spot on each fluorescent part according to each color tone. As a material for shadow masks,
It is required to have excellent etching properties so that an accurate electron beam passage hole is formed, and a low-carbon Al-killed steel has been conventionally used. However, shadow masks
It is overheated and thermally expanded by the collision of the electron beam. If the thermal expansion at this time is large, the electron beam passage hole is displaced, and a so-called doming phenomenon occurs in which the beam spot does not hit a predetermined phosphor screen. The doming phenomenon has become a serious problem as color televisions, display panels, and the like have been improved in accuracy and luminance.

[0003] Since the doming phenomenon is suppressed by using a shadow mask material having a low thermal expansion characteristic,
For a picture tube requiring a clear image, F
An e-Ni alloy plate has begun to be used as a shadow mask material. However, since the Fe-Ni-based alloy plate contains a large amount of Ni, the material cost is higher than that of the low-carbon Al-killed steel. Further, as compared with a low carbon Al-killed steel, the mechanical strength is high and the press formability is poor, and the Young's modulus is low and the rigidity is poor. Concerning the etching properties, it is a disadvantage that the etching rate is lower than that of the low carbon steel and the etching piercing property is inferior. Above all, stripes appearing in a shadow mask after etching are a serious problem because the quality of a cathode ray tube is deteriorated.

[0004] Various measures have conventionally been proposed in order to eliminate streaks. For example, a casting method, a hot working method, a heat treatment method, and the like for eliminating component segregation are known on the premise that component segregation of Ni and other elements is a cause of stripe unevenness (Japanese Patent Application Laid-open No. Sho. JP-A-60-56053, JP-A-60-128253, JP-A-2-54743.
JP, JP-A 1-225225, etc.).

[0005]

With the recent tendency of color televisions and OA equipment display panels to be larger and more multimedia, the electron beam passage hole having a smaller hole diameter than the conventional one is required. There is an increasing demand for shadow masks that are perforated at a high density and that have a fine pitch between holes. In a shadow mask that drills electron beam passage holes with a small diameter at a fine pitch,
Conventionally proposed measures for improving stripe unevenness are not so effective, and the stripe unevenness has not been sufficiently eliminated.

[0006]

SUMMARY OF THE INVENTION The present invention has been devised to solve such a problem, and increases the degree of (200) plane integration in a cross section perpendicular to the rolling direction. An object of the present invention is to provide a shadow mask in which unevenness is suppressed by forming irregularities larger than irregularities on the etched surface and randomizing reflected light from the etched surface.

In order to achieve the object, the Fe—Ni-based alloy plate for a shadow mask according to the present invention includes Ni: 30 to 50% by mass, C: 0.015% by mass or less, Si: 0.20% by mass or less, Mn: 0.5% by mass or less, Al: 0.02% by mass or less, B: 0.0040% by mass or less, the balance being substantially Fe, and (2) in a section perpendicular to the rolling direction.
00) The degree of surface integration is 40% or more.
This Fe—Ni-based alloy sheet for a shadow mask is manufactured by cold-rolling the Fe—Ni-based alloy sheet having the above-described composition at a rolling reduction of 75% or more immediately before finish annealing.

[0008]

The present inventors have studied in detail the relationship between the form of streaks generated in the Fe-Ni alloy sheet material and the component segregation. As a result of closely observing the shadow mask in which the stripes were generated, it was found that the etched surface of the perforated portion 3 had more irregularities than a shadow mask having no stripes. Therefore, for the cross section 1 perpendicular to the rolling direction D, Ni
Was analyzed by an X-ray microanalyzer. As a result, the Ni deficiency layer 2 was distributed in a layered manner (FIG. 1). Ni
The deficiency layer 2 is one in which the micro-negative segregation generated between the dendrite trees generated at the time of casting remains without being eliminated even after the rolling process and the heat treatment in the processes after the hot-rolling. Although macro component segregation may occur due to the flow of residual molten steel in the solidification process, such large fluctuations in concentration are hardly eliminated in the final product stage. The negative segregation at the time of casting is compressed in the thickness direction by the rolling process, and remains in a form elongated in the rolling direction.

A change in the Ni concentration along the thickness direction causes a difference in the etching rate, and causes minute irregularities in the formed etching perforated portion 3. According to the distribution form of the Ni-deficient layer 2, the irregularities appear in the etching perforations 3 connected in the rolling direction D with continuity.
It changes discontinuously in the width direction perpendicular to the rolling direction D. As a result, the path of light transmitted or reflected by the shadow mask is deviated, and streaking is observed as a light-dark difference parallel to the rolling direction D.

Next, when the influence of the texture of the material on the morphology of the etched surface was investigated, it was found that the degree of unevenness on the side-etched surface of the etched hole 3 was different depending on the texture of the material. When a shadow mask is pierced by photoetching, etching proceeds in the depth direction, in other words, in the plate thickness direction, and at the same time, side etching proceeds in a direction orthogonal to the plate thickness direction. According to investigations and studies by the present inventors, it has been found that the morphology of the side-etched surface differs for each crystal grain, and that the influence of the plane orientation of each crystal grain on the side-etched surface is particularly large.

The effect of the texture on the size and shape of the electron beam passage hole has been known in the art. For example, Japanese Patent Application Laid-Open No. S59-40443 discloses that the degree of (200) plane integration of a plate surface is 35%. It is reported that a uniform shape electron beam passage hole can be obtained by the above. In Japanese Patent Laid-Open Publication No. Hei 5-9658, the degree of integration of the (200) plane in the plane parallel to the plate surface at the center of the plate thickness is 30%.
By making the above, and making it larger than the plate surface, the side etching is suppressed. However, none of these methods regulates the texture of the plate surface or a plane parallel to the plate surface, and does not clarify the effect of the method on irregularities generated on the etched surface of the perforated portion.

The form of the etched surface of the perforated portion is affected by the etching behavior in the direction of side etching, that is, in the direction perpendicular to the thickness direction. Therefore, the influence of the crystal plane orientation of the plane perpendicular to the plate surface appears largely on the etched surface together with the above-described fluctuation of the Ni concentration in the plate thickness direction. Therefore, the present inventors have further studied and found that as the material has a higher degree of integration of the (200) plane orientation in a cross section perpendicular to the rolling direction, the unevenness generated on the etched surface increases. When the degree of integration of the (200) plane is set to 40% or more, irregularities more than minute irregularities caused by segregation are formed. As a result, it is presumed that the path of the transmitted light is randomized, the optical deviation caused by the fine pitch unevenness due to segregation is canceled out, and no stripes are observed.

(200) in a section perpendicular to the rolling direction
The surface integration degree is measured as follows. A large number of test pieces having a size of about 20 mm square are prepared by shearing the material, the test pieces are rolled up in the same rolling direction, fixed with a resin or the like, and then a cross section perpendicular to the rolling direction is ground and polished. Then
The diffraction peak on the polished surface was measured using an X-ray diffractometer, and (111), (200), (220),
The relative integrated intensity ratio of each of the (311) planes was determined, and the total of the relative integrated intensity ratios was defined as 100, and the percentage of the relative integrated intensity ratio of the (200) plane was defined as the (200) plane integration degree. Note that the relative integrated intensity ratio is a value obtained by dividing the integrated intensity of each surface by the theoretical integrated intensity of that surface. Alternatively, a polycrystal in which the crystal plane orientation is completely random in the same alloy system may be used as a standard sample, and the measured value of the integrated intensity for each of these surfaces may be used instead of the theoretical integrated intensity.

Hereinafter, the components and contents of the Fe—Ni alloy used in the present invention will be described. Ni: 30 to 50% by mass Ni is an important alloy component for maintaining a low coefficient of thermal expansion of the Fe-Ni-based alloy sheet, and has a Ni content of 30 to 50 to obtain low thermal expansion characteristics required for shadow mask applications. Regulate in the range of mass%.

C: 0.015% by mass or less C is a harmful component that forms carbides in the Fe—Ni-based alloy sheet material and impairs the etching property. By restricting the C content to 0.015% by mass or less, it is possible to prevent the etching property from being lowered by the carbide. Si: 0.20% by mass or less An alloy component added as a deoxidizing agent during steelmaking, but tends to increase the coefficient of thermal expansion and deteriorate the etching properties and the blackening film properties. Such adverse effects are suppressed by setting the Si content to 0.20% by mass or less. Mn: 0.5% by mass or less An alloy component added as a deoxidizing agent during steelmaking, but the upper limit of the Mn content is set to 0.
It was set to 5% by mass.

Al: 0.02 mass% or less Al is an alloy component added as a deoxidizing agent during steelmaking, but promotes generation of surface flaws and degrades the surface quality of the Fe—Ni-based alloy sheet. Was set to 0.02% by mass. B: 0.0040% by mass or less B is an effective alloy component for improving the etching property. However, if B exceeds 0.0040% by mass, annealing unevenness is likely to occur after softening annealing, and the blackening film Generation unevenness is also promoted. Therefore, the B content has an upper limit of 0.00
It is defined as 40% by mass. Fe-Ni targeted by the present invention
Alloys include S, P, O, N as other unavoidable components.
Etc., but the content of unavoidable components is 0.01
When the content is regulated to 0% by mass or less, the characteristics as a material for a shadow mask are not adversely affected.

(200) in a section perpendicular to the rolling direction
Surface integration: 40% or more (200) surface integration in a cross section perpendicular to the rolling direction is:
This is an effective index that accurately indicates the progress of side etching that proceeds isotropically in all directions perpendicular to the thickness direction. When the (200) plane integration degree is 40% or more (preferably 60% or more), the influence of unevenness due to segregation is negated, and an etched surface in which no stripes are observed is obtained. On the other hand, 4
When the degree of (200) plane integration is less than 0%, unevenness due to unevenness due to segregation starts to be observed. (200) The Fe—Ni-based alloy sheet having a surface integration degree of 40% or more specifically has a reduction rate of 75 immediately before finish annealing during cold rolling and annealing after hot rolling.
% Or more and obtained by finish annealing at 800 ° C. When the rolling ratio is 80% or more and the finish annealing temperature is 800 ° C. or more, the degree of (200) plane integration becomes 60% or more.

[0018]

EXAMPLE After melting in an electric furnace and rough decarburization in a converter, Ni: 36.07% by mass and C: 0.005 in a vacuum degassing apparatus.
% By mass, Si: 0.04% by mass, Mn: 0.31% by mass, Al: 0.010% by mass, B: 0.0011% by mass
Was melted, and an ingot was produced by an ingot-making method. After heating the ingot to a temperature of 1200 ° C. or higher, the ingot was slab-rolled to produce a slab having a thickness of 180 mm. After the surface of the obtained slab is cleaned, the plate thickness is 4m.
m hot-rolled sheet. The hot-rolled sheet was annealed and pickled, cold-rolled and annealed repeatedly to finally obtain a cold-rolled sheet having a thickness of 0.12 mm. Various changes in the intermediate rolling rate during this manufacturing process,
As shown in Table 1, in the section perpendicular to the rolling direction (20
0) Materials with different degrees of surface integration were produced.

A test piece cut from each cold-rolled plate was subjected to photoetching, and the occurrence of streaking was examined. In the photoetching, a photoresist is applied to the surface of the test piece in a predetermined pattern for a high-definition shadow mask, exposed and developed, and then a ferric chloride solution having a liquid specific gravity of 47 Baume and a liquid temperature of 50 ° C. is sprayed at a pressure of 2 kgf / cm. ^{In 2} the test piece was sprayed on the surface. The etched specimens were visually observed to investigate the occurrence of streaking. The highest level A is that no streaking is observed, the level B is that there is almost no streaking and can be used for a high-definition shadow mask, and the level C is that where a relatively large number of streaks are observed. Those having a large number of streaks were evaluated as the lowest level D, and the streak quality was evaluated on a four-point scale.

As can be seen from the examination results in Table 1, test pieces 1-4 (examples of the present invention) cut out from cold-rolled sheets having a (200) plane integration of 40% or more in a cross section perpendicular to the rolling direction.
In this example, the streak quality was level B or higher, and the quality was sufficiently usable for a high-definition shadow mask. On the other hand, (20) in a cross section perpendicular to the rolling direction
0) In the test pieces 5 to 6 (comparative example) in which the degree of surface integration is less than 40%, the streak quality is lower than or equal to the level C, which does not sufficiently satisfy the characteristics required for a high-definition shadow mask. Was. In addition, as shown in FIG. 2 in which the relationship between the (200) plane integration degree and the streak unevenness is graphed,
It can be seen that the level of the uneven stripes becomes higher as the degree of integration of the (200) plane increases, and reaches the level A and B when the degree of integration of the (200) plane is 40% or more.

[0021]

[0022]

As described above, as described above, the Fe-
The Ni-based alloy sheet has a cross section perpendicular to the rolling direction (20
0) By setting the degree of surface integration to 40% or more, an optical bright and dark pattern (striation unevenness) caused by minute unevenness due to segregation is eliminated, and the material is suitable for a shadow mask.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing Ni segregation of an Fe—Ni alloy plate perforated by etching.

FIG. 2 is a graph showing the effect of (200) plane integration on the stripe quality in a cross section perpendicular to the rolling direction.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Takashi Yamauchi 4976 Nomura Minamimachi, Shinnanyo-shi, Yamaguchi Prefecture F-term (reference) 4N037 EA01 EA02 EA04 EA05 EA15 EA21 EA27 FG10 FJ05 HA04 JA02 JA06 5C027 HH02 HH03 5C031 EE05 EH08

Claims (2)

[Claims] 1. Ni: 30 to 50% by mass, C: 0.01
5% by mass or less, Si: 0.20% by mass or less, Mn: 0.
5 mass% or less, Al: 0.02 mass% or less, B: 0.0
040% by mass or less, and the balance substantially has a composition of Fe;
The (200) plane integration degree in the cross section perpendicular to the rolling direction is 4
F for shadow mask which suppresses stripe unevenness of 0% or more
e-Ni alloy plate. 2. Ni: 30 to 50% by mass, C: 0.01
5% by mass or less, Si: 0.20% by mass or less, Mn: 0.
5 mass% or less, Al: 0.02 mass% or less, B: 0.0
040% by mass or less, with the balance being substantially Fe
The e-Ni-based alloy sheet is cold-rolled by setting the rolling ratio immediately before finish annealing to 75% or more so that the (200) plane integration degree in a cross section perpendicular to the rolling direction is 40% or more. Fe- for shadow mask with reduced unevenness
A method for producing a Ni-based alloy plate.