JP2002275540A - METHOD FOR MANUFACTURING Fe-Ni ALLOY SHEET FOR SHADOW MASK - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an Fe-Ni alloy sheet for shadow mask free from striped irregularity. SOLUTION: Soaking treatment is applied to a hot rolled plate composed of Ni-Fe alloy containing 30-50 mass% Ni under the condition that heating temperature (T) is 900-1,000( deg.C) and heating temperature (T) and holding time (t) satisfy 600<=T×log(t)<=1,200 to form a structure of grain size No.3 or above. Successively, after the removal of oxide scale from the surface, intermediate cold rolling at >=80% draft and process annealing at 850-1,000 deg.C are applied to form an intermediate stock having a graded structure of grain size No.4 or above. Then the stock is cold-rolled and annealed or is cold-rolled, annealed and further temper-rolled to undergo finishing to the prescribed sheet thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an Fe--Ni alloy plate for a shadow mask used for a cathode ray tube of a display for a color television or a personal computer.

[0002]

2. Description of the Related Art A shadow mask is used for a cathode ray tube of a display for a color television or a personal computer. In this shadow mask, a large number of fine holes are formed in a thin metal plate by a photoetching method. And
An image is formed by projecting an electron beam emitted from an electron gun disposed inside the cathode ray tube through the fine holes of the shadow mask and projecting it onto a phosphor.

[0003] Of the electron beams emitted from the electron gun, only a few are projected on the phosphor through the fine holes of the shadow mask, and most of the remaining electrons collide with the shadow mask. Therefore, the shadow mask made of low carbon aluminum killed steel, which has been conventionally used, has a problem that the image is blurred due to thermal expansion due to an impinging electron beam during continuous use, causing color shift (doming). is there. In particular, as color displays have become larger and higher in quality, degradation in image quality due to doming has become noticeable.

[0004] In order to solve this problem, F has an extremely small coefficient of thermal expansion as compared with conventional low carbon aluminum killed steel.
An e-Ni alloy is used. As used herein, the term “Fe—Ni alloy” refers to an Invar alloy (an alloy containing 36% Ni), which contains 30 to 50% of Ni and substantially the remainder is F.
This is an alloy composed of e.

[0005] The shadow mask made of the Fe-Ni alloy is widely used because the deterioration of the image quality due to doming is small. In particular, in the case of a display for a personal computer, a fine shadow mask having a small hole diameter and a fine pitch is becoming mainstream, and the demand is increasing more and more.

However, as shadow masks have been refined, it has been considered that linear etching unevenness along the rolling direction is present in the holes of the shadow mask. This etching unevenness is generally called a streak, and since the roughness of the wall surface of the hole formed by the etching process is locally different, the density of the light irregularly reflected there is seen as streak-like color unevenness.

[0007] As a method of manufacturing an Fe-Ni alloy plate capable of improving the unevenness of the shadow mask, the following methods have been proposed.
A method has been proposed.

The ingot is heated to a temperature of 850 ° C. or higher and a melting point or lower before forging (Japanese Patent Laid-Open No. 60-128253).

[0009] The ingot is subjected to a soaking treatment in which the ingot is maintained at a temperature of not less than 1150 ° C and a melting point but not less than 1 hour and not more than 30 hours. The soaking is performed under specific conditions (Japanese Patent Application Laid-Open No. 9-241743).

After hot rolling the slab or the slab, a soaking treatment is performed under specific conditions (Japanese Patent Laid-Open No. 1-2527).
No. 25).

An ingot or a slab in which the contents of Mn and S are controlled to be low is subjected to a soaking treatment at 1180 to 1320 ° C. for 8 hours or more (JP-A-8-74002).

The hot-rolled sheet is annealed at 1000 to 1400 ° C. (JP-A-2-50919).

The hot-rolled sheet is annealed at 800 ° C. or lower for one hour or more (Japanese Patent Laid-Open No. Hei 9-137220).

The above methods (1) to (4) improve the uneven streaks by reducing component segregation. However, it is extremely difficult to improve the uneven streaks to the level required for recent high-definition shadow masks only by reducing component segregation.

Further, in order to reduce uneven streaks as much as possible,
In order to reduce component segregation, the above-mentioned methods require long-term soaking at a very high temperature. Therefore, the energy cost in the soaking process increases.
Further, since the oxide scale generated on the surface becomes thick, the amount of surface grinding for removing the scale increases, and the yield decreases and the number of grinding steps increases.

According to the other method, component segregation can be reduced in a relatively short time. However, when the hot-rolled sheet is annealed under the conditions described herein, excessive oxide scale is generated on the surface, and the yield is greatly increased. And the number of steps for removing the scale increases. Further, when the hot rolled sheet is soaked at a temperature higher than the recrystallization temperature, the crystal grains become extremely coarse. If the crystal grains of the hot-rolled sheet become extremely coarse, a mixed grain structure is likely to occur in the annealing process after cold rolling, and as a result, the cold-rolled sheet is liable to generate uneven streaks due to uneven distribution of crystal orientation.

The method (1) is to prevent a mixed grain structure and to prevent unevenness of etching accompanying the mixed grain structure, thereby reducing uneven streaks. However, according to this method, component segregation cannot be sufficiently reduced due to a low annealing temperature, so that uneven streaks due to component segregation occur.

[0018]

SUMMARY OF THE INVENTION An object of the present invention is to prevent segregation of components and non-uniformity of crystal orientation, and to prevent Fe-N for a shadow mask from causing uneven streaks caused by these.
An object of the present invention is to provide a method for manufacturing an i-alloy plate.

[0019]

According to the present invention, there is provided a method for manufacturing a semiconductor device, comprising:
A hot-rolled sheet made of a Ni-Fe alloy containing Ni in an amount of 3% by mass is subjected to a soaking treatment under conditions satisfying the following equations (1) and (2) to obtain a structure having a ferrite grain size of 3 or more, Then, after removing the oxide scale on the surface, a reduction ratio of 80% or more is subjected to intermediate cold rolling and an intermediate annealing at 850 to 1000 ° C. to obtain an intermediate material having a ferrite grain size of 4 or more. Then, cold-rolled and then annealed, or cold-rolled and then annealed and temper-rolled to finish Fe-N for a shadow mask to a predetermined thickness.
The method is for manufacturing an i-alloy plate.

900 ° C. ≦ T ≦ 1000 ° C. Expression (1) 600 ≦ T × log (t) ≦ 1200 Expression (2) where T: heating temperature in soaking heat treatment (° C.) t: in soaking heat treatment Retention time (hr).

In order to eliminate the uneven streaks of the shadow mask, the inventors used a cold-rolled sheet before micro holes were formed,
We thought that it was necessary to make the entire surface uniformly etchable. That is, the component segregation of the cold-rolled sheet is reduced, and the crystal grain size of the cold-rolled sheet is made uniform so that the uneven distribution of the crystal orientation is suppressed.

Therefore, the hot rolled sheet is subjected to soaking treatment to reduce component segregation, and the ferrite crystal grain size of the intermediate material obtained by the intermediate cold rolling and the intermediate annealing is set to a grain size of 4
With the above structure having a uniform crystal grain size (hereinafter, referred to as a sized structure), non-uniformity of etching caused by component segregation or uneven distribution of crystal orientation is suppressed, and unevenness of the shadow mask is eliminated. I found that I could do it. The present invention is based on the above findings.

In the following description, "grain size"
Means “ferrite grain size”.

In the present invention, the grain-sized structure means a structure having a ferrite crystal grain size of 1 or less in grain size number.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the reason why the content of Ni in the Fe—Ni alloy plate for a shadow mask to which the present invention is applied is limited will be described. The present invention is directed to an alloy plate made of an alloy having an extremely small coefficient of thermal expansion generally called an invar alloy. When the content of Ni is less than 30% by mass or exceeds 50% by mass, the coefficient of thermal expansion increases. Thus, doming is likely to occur. Therefore, the content of Ni is
30 to 50% by mass.

The impurities contained in the alloy plate are as follows:
The following is preferred.

C: If the content of C is large, carbides precipitate and the porosity by etching deteriorates.
The following is assumed.

Si: Since Si increases the amount of inclusions and contaminates the etching solution, the content of Si is set to 0.05% or less.

Mn: Mn is used as a deoxidizing agent at the time of melting, but when contained in a large amount, hot workability is reduced and inclusions are increased. In addition, it prevents formation of a blackened film in a blackening process performed after processing the shadow mask. Therefore, it is set to 1.0% or less.

Al: Al is used as a deoxidizing agent at the time of smelting, but inclusion of a large amount increases inclusions.
0.02% or less.

O: If O is contained in a large amount, metal oxide-based inclusions increase, and defects are likely to occur in holes formed in the shadow mask.

Further, the alloy plate may contain trace amounts of B and Ca in order to improve workability during hot rolling.

Next, the manufacturing method will be described.

[Soaking heat treatment] Fe having the above chemical composition
-A soaking treatment is performed on the hot rolled sheet made of the Ni alloy under the conditions satisfying the following formulas (1) and (2) to make the grain size 3 or a finer structure.

900 ° C. ≦ T ≦ 1000 ° C. Formula (1) 600 ≦ T × log (t) ≦ 1200 Formula (2) where T: heating temperature in soaking heat treatment (° C.) t: in soaking heat treatment Retention time (hr).

Component segregation of the Fe—Ni alloy occurs in the solidification stage of casting. A cold rolled sheet manufactured from a steel ingot with component segregation without performing a process to improve component segregation,
Naturally, component segregation exists. Therefore, when this is etched to form a shadow mask, remarkable uneven streaks occur. Therefore, in order to reduce the segregation of components generated in the casting stage, it is effective to perform a soaking process in the state of a steel ingot, a slab, or a hot-rolled sheet to diffuse the components. The diffusion of segregated components in the steel by soaking depends on the heating temperature and the holding time.
The shorter the diffusion distance, the more efficiently the component segregation can be reduced. In other words, rather than performing soaking on steel ingots and slabs with relatively large diffusion distances, by performing soaking on hot-rolled sheets with a small thickness and small diffusion length, component segregation can be reduced in a short period of time. It is effective from the viewpoint of improving the performance. Therefore, in the present invention, a soaking treatment is performed on the hot-rolled sheet.

By the way, when the hot-rolled sheet is soaked at a temperature equal to or higher than the recrystallization temperature, the crystal grain size is remarkably larger than the crystal grain size of the hot-rolled sheet not subjected to soaking (normally, grain size number 8 to 10). Coarse. (Hereinafter, the crystal grains coarsened by the soaking treatment are referred to as initial coarse grains).

The hot rolled sheet having the initial coarse grains is
The intermediate material obtained by the intermediate cold rolling and intermediate annealing described below has a mixture of small crystal grains in which recrystallized grains have started to grow at crystal grain boundaries and large crystal grains in which the original initial coarse grains remain. It is easy to be in a state (mixed particle state).

In particular, when the crystal grain size of the hot-rolled sheet is coarsened to a grain size number less than 3, it is difficult to prevent the mixed grain state generated in the intermediate material by heat treatment. Therefore, the soaking heat treatment applied to the hot-rolled sheet must be performed under the condition that the crystal grain size is 3 or more. Specifically, the heating temperature (T) is set to 900 to 1000 ° C. defined by the above formula (1), and the relationship between the heating temperature (T) and the holding time (t) is set to the above formula (2).

If the heating temperature in the soaking treatment is lower than 900 ° C., component segregation cannot be diffused. On the other hand, 10
When the temperature exceeds 00 ° C., the crystal grains become remarkably easy to grow,
In a short time, the grain size reaches less than grain size number 3. Further, when heated to a high temperature exceeding 1000 ° C., there is a disadvantage that the surface is excessively grain boundary oxidized, and the yield is greatly reduced by descaling. Therefore, the heating temperature in the soaking is set to 900 to 1000 ° C.

If T × log (t), which represents the holding time in the soaking treatment in relation to the heating temperature, is less than 600, component segregation cannot be sufficiently diffused. On the other hand, 1200
If the number exceeds 3, the growth of crystal grains becomes remarkable, and it is inevitable that the crystal grain size becomes smaller than particle size number 3. Therefore,
The holding time in the soaking process is a time (t) that satisfies the condition of the above equation (2) in relation to the heating temperature. In addition,
In order to suppress surface oxidation, the holding time is preferably set to 15 hours or less. Therefore, when the holding time (t) satisfying the condition of the above equation (2) exceeds 15 hours, the holding time is set to 15 hours or less. Is preferred.

The degree of growth of crystal grains when the soaking treatment is performed on the hot-rolled sheet varies depending on the thickness of the hot-rolled sheet, the heating temperature and the holding time. Therefore, the crystal grain size is 3
The conditions may be determined within the range of the heating time and the range of the holding time according to the thickness of the sheet, so long as the thickness does not grow below. In order to efficiently promote component diffusion by soaking, it is preferable to set the thickness of the hot-rolled sheet to about 3 to 10 mm.

In order to perform the soaking treatment under the above conditions, a heat treatment furnace such as a continuous annealing furnace which performs treatment in a short time is not suitable. It is preferable to use a batch type annealing furnace. In this case, to minimize the surface oxidation of the hot-rolled sheet, a method of soaking in a non-oxidizing atmosphere or a reducing atmosphere, a method of soaking a coiled hot-rolled sheet with an iron box, One of the methods such as wrapping an iron plate around a hot rolled plate and absorbing heat in the atmosphere while absorbing heat
It is desirable to use one or more methods in combination.

[Oxide scale removal treatment] Subsequently, the oxide scale generated on the surface of the hot-rolled sheet subjected to the soaking treatment is removed. Examples of a method for removing the oxide scale include surface polishing, shot blasting, and pickling treatment, but are not particularly limited.

[Intermediate cold rolling and intermediate annealing]
Intermediate cold rolling with a rolling reduction of 80% or more, and 850 to 100
Intermediate annealing is performed at 0 ° C. to obtain an intermediate material having a grain size of 4 or smaller. The crystal grain size is a grain size number obtained by a comparison method in a ferrite crystal grain size test method specified in JIS G 0552.

When a cold rolled sheet made of an Fe—Ni alloy is etched with a ferric chloride solution, the etching properties (etching speed and roughness of the etched surface) depend on the crystal orientation appearing on the surface of the cold rolled sheet. Etc.) are known to be different. If the surface of the cold-rolled sheet is in a state where the crystal orientations in the groups are the same but the crystal orientations in each group are different (hereinafter, referred to as uneven distribution of crystal orientations), the etching property differs for each crystal orientation. It will appear as stripes on the shadow mask.

In order to prevent the crystal orientation from being unevenly distributed on the surface of the cold-rolled sheet, it is important to prevent the crystal grains of the intermediate material from having a mixed grain structure. That is, the fact that the crystal grains of the intermediate material are in a mixed state means that the crystal orientation originally possessed by the initial coarse grains still remains in the intermediate material. Cold-rolled sheet obtained by cold rolling and annealing such an intermediate material, even though apparently in a state where the size of the crystal grains are uniformly uniform, because it was in a mixed state at the stage of the intermediate material In addition, the crystal orientation of the initial coarse grains is stretched by rolling as it is to form a crowd. This state is that the crystal orientation is unevenly distributed on the surface of the cold-rolled sheet, which causes uneven streaks. This phenomenon becomes more remarkable as the mixed state of the intermediate material becomes stronger.

Therefore, in order to eliminate the uneven distribution of crystal orientation in the cold-rolled sheet, the initial coarse grains of the hot-rolled sheet are sufficiently disintegrated and recrystallized by intermediate cold rolling and intermediate annealing so that the crystal grain size becomes 4 As described above, it is necessary to have a sized structure.

The reason for setting the crystal grain size to be 4 or more is as follows. That is, when the grain size is less than grain size number 4, the grain size of the cold-rolled sheet after the subsequent cold rolling and annealing, or further after the temper rolling becomes a mixed grain structure. Also, in order to form fine holes to make a shadow mask,
It is desirable to make the crystal grain size of the cold-rolled sheet as small as possible (for example, grain size number 9 or more). For this purpose, it is preferable that the grain size of the intermediate material is grain size number 4 or more.

In general, in order to promote recrystallization, it is effective to provide a driving force for recrystallization by increasing the rolling reduction of the cold rolling and to perform annealing at a higher temperature. According to the study by the inventors, if the initial coarse grains are a grain size number of 3 or more, the intermediate coarse rolling at a rolling reduction of 80% or more is performed and then the intermediate annealing process described below is performed to reduce the initial coarse grains. It is possible to obtain an intermediate material which is sufficiently collapsed and recrystallized to have a crystal grain size of 4 or more and is sized.
If the rolling reduction of the intermediate rolling is less than 80%, the driving force for recrystallization is insufficient, so the rolling reduction is set to 80% or more.
The upper limit of the rolling reduction is not particularly defined. It may be determined according to the equipment specifications to be used. Intermediate annealing temperature is 850 ° C
If it is less than 1, the mixed grains are formed regardless of the rolling reduction of the intermediate cold rolling. On the other hand, when the temperature exceeds 1000 ° C., the crystal grains of the intermediate material further grow and become extremely coarse.

The holding time in the intermediate annealing is 0.5
Approximately 5 minutes is sufficient, and it may be performed in a normal continuous annealing line.

As described above, a hot-rolled sheet having a grain size of 3 or more is subjected to intermediate cold rolling at a rolling reduction of 80% or more,
By performing the intermediate annealing at 850-1000 ° C.,
An intermediate material having a crystal grain size of 4 or more and a grain size structure is obtained.

[Finish Rolling and Finish Annealing] The intermediate material manufactured as described above is subjected to at least one or more cold rollings and annealings, and further, if necessary, temper rolling to obtain a predetermined sheet thickness and a machine. -N for shadow mask with high mechanical strength
i-alloy plate.

The rolling reduction of the cold rolling is defined in relation to the thickness of the intermediate material and the thickness of the cold rolled sheet, and may be about 50 to 95%.

If the annealing temperature is too low, recrystallization is not promoted, while if it is too high, the required mechanical properties may not be obtained due to excessive softening.

The temper rolling is for obtaining the required strength and hardness, and is performed at a rolling reduction of about 1 to 40%.

The method for producing the Fe—Ni alloy material according to the present invention may be either the ingot casting method or the continuous casting method. However, the continuous casting method is desirable from the viewpoint of reducing the production cost or improving the productivity. Furthermore, in order to reduce component segregation, a soaking treatment at the ingot stage or a soaking treatment at the slab stage may be combined.

[0058]

EXAMPLE An Fe-Ni alloy having the chemical composition shown in Table 1 was melted in an electric furnace, and a 7-ton ingot was manufactured by an ingot-making method.

[0059]

[Table 1] The above-mentioned ingot is lumped with a press, and the plate thickness is 150 mm.
And a hot-rolled sheet having a thickness of 6 mm by hot rolling.

After subjecting this hot-rolled sheet to soaking treatment in a non-oxidizing atmosphere, the oxide scale on the surface is removed by grinding.
Next, an intermediate material was formed by intermediate cold rolling and intermediate annealing, and the grain size of the hot-rolled sheet and the intermediate material was investigated.

Table 2 shows the conditions of the soaking treatment applied to the hot-rolled sheet, the rolling reduction in the intermediate cold rolling, the heating temperature in the intermediate annealing, and the crystal grain size. The holding time in the intermediate annealing was all 1 minute.

[0062]

[Table 2] Grain size is obtained by collecting test specimens from hot-rolled sheet and intermediate material,
After polishing the cross section orthogonal to the rolling direction of each test piece, immersed in a ferric chloride solution, using an optical microscope of 100 times,
It was determined by a comparative method of the ferrite crystal grain size test method specified in JIS G 0552. The particle size numbers shown in Table 2 show these two values when the difference between the maximum and the minimum of the particle size numbers in one visual field is 1 or more, and when the difference between the particle size numbers is less than 1, one value is used. Show.

In the case of the intermediate material, the difference between the maximum and the minimum of the particle size numbers in one visual field is defined as the degree of mixing, and the difference is within 1; the difference is more than 1 and less than 3; X.

Next, the above-mentioned intermediate material was subjected to finish annealing at a temperature of 800 ° C. for a holding time of 1 minute by cold rolling to a sheet thickness of 0.2 mm, and further to a sheet thickness of 0.1 mm by temper rolling.
A 6 mm cold rolled sheet was manufactured. After the cold-rolled plate was degreased and washed, a photoresist resin was applied to the surface, and a dot-hole pattern was formed thereon. Then, a ferric chloride solution having a temperature of 60 ° C. and a specific gravity of 1.48 g / cm ³ was sprayed to perform etching, and the diameter was 0.23 mm and the pitch was 0.2.
After forming a 6 mm dot hole, the photoresist film on the surface was removed.

The dot holes thus formed were visually observed with oblique light and transmitted light, and the occurrence of uneven streaks was investigated. The results are shown in Table 2. The occurrence of uneven streaks was evaluated as ○ when no uneven streaks were observed, Δ when weak streaks were observed, and x when strong streaks were observed.

As can be seen from Table 2, no. 1 to No.
In the present invention sample No. 10, the hot-rolled sheet has a grain size of 3 or more, the intermediate material has a grain size of 4 or more, no mixed grains are observed, and no streaks are generated.

On the other hand, no. 11, the heating temperature in the soaking heat treatment was low. 1
No. 2, the heating temperature in the soaking treatment was low and the holding time was long, so that the conditions of the above formula (2) were not satisfied. No. 13 and No. which deviated from the condition of the above equation (2) due to the short holding time in the soaking treatment In No. 14, component segregation could not be sufficiently reduced, and uneven streaks caused by segregation occurred.

Since the holding time in the soaking process is long, the conditions of No. 15 and no. No. 16 and No. 16 in which the heating temperature in the soaking heat treatment of the hot rolled sheet was high. 17
-No. In No. 19, the grain size of the hot-rolled sheet was coarsened, and
Since mixed grains were generated in the intermediate material, uneven streaks occurred due to non-uniform crystal orientation.

The heating temperature of the intermediate annealing was low. No. 20, the heating temperature of the intermediate annealing is high. No. 21 and No. 21 in which the rolling reduction of the intermediate rolling is low. 22-No. In No. 25, mixed grains occurred in the intermediate material, and uneven streaks caused by non-uniform crystal orientation occurred.

[0070]

According to the manufacturing method of the present invention, it is possible to prevent segregation of components and non-uniformity of the crystal orientation, so that an Fe-Ni alloy plate for a shadow mask free from the occurrence of streaks caused by these can be manufactured. be able to.

Claims (1)

[Claims] 1. Ni- containing 30 to 50% by mass of Ni.
The following formulas (1) and (2) are applied to a hot rolled sheet made of an Fe alloy.
After performing a soaking treatment under the conditions satisfying the formula to obtain a structure in which the ferrite crystal grain size is 3 or more, and after removing the oxide scale on the surface, intermediate cold rolling with a rolling reduction of 80% or more and 850 to 1000 ° C. Is subjected to intermediate annealing to obtain an intermediate material having a grain size structure with a ferrite crystal grain size of 4 or more, and then cold-rolled and then annealed, or cold-rolled and then annealed and then temper-rolled, A method for producing an Fe-Ni alloy plate for a shadow mask, characterized in that the plate thickness is finished. 900 ° C. ≦ T ≦ 1000 ° C. Formula (1) 600 ≦ T × log (t) ≦ 1200 Formula (2) where T: heating temperature in soaking heat treatment (° C.) t: holding time in soaking heat treatment ( hr)