WO2001023631A1

WO2001023631A1 - Fe-Ni ALLOY FOR SHADOW MASK AND METHOD FOR PRODUCTION THEREOF

Info

Publication number: WO2001023631A1
Application number: PCT/JP2000/004546
Authority: WO
Inventors: Norio Yuki; Tomoji Mizuguchi; Akihiro Ito; Hitohisa Yamada; Sou Ueda; Takahiro Kishimoto
Original assignee: Nippon Mining & Metals Co., Ltd.; Japan Steel Works Co., Ltd.
Priority date: 1999-09-29
Filing date: 2000-07-07
Publication date: 2001-04-05
Also published as: JP2001098345A; KR20020053816A; KR100497590B1

Abstract

A Fe-Ni alloy for a shadow mask which comprises, in wt %, 30 to 50 % of Ni and 0.5 % or less of Mn, the balance of the alloy being Fe and inevitable impurities, and contains, in a cross section perpendicular to the direction of rolling of an alloy thin plate immediately before etching, segregation regions (bands) having a difference in Ni concentration of 0.7 % or more in an amount of 1.0 piece or less per 100 mm in the direction of the width of the plate. The Fe-Ni alloy can be used, in a shadow mask having a fine pitch, for suppressing the occurrence of striped irregularities at a hole for passing an electron beam

Description

Description Fe-Ni alloy for shadow mask and method of manufacturing the same Background of the invention

The present invention relates to a material for a shadow mask to be finely etched, and more particularly to a Fe—Ni-based alloy in which the occurrence of streaks in finely etched is suppressed.

In recent years, Fe—Ni alloys with low thermal expansion are often used in shadow masks for color cathode ray tubes from the viewpoint of color purity. The electron beam transmission holes in the shadow mask are formed by micro-etching, and the Fe—Ni-based alloy shadow mask, when compared to the mild steel shadow mask used conventionally, There is a disadvantage that a defect called a streak tends to occur. In addition, this stripe unevenness can be confirmed by observing the small hole side of the shadow mask as a front surface and obliquely observing light from the back side so that the etching wall surface of the transmission hole shines.

1-? In the case of a hexagonal alloy, the cause of uneven streaks is the segregation of Ni components. If a concentration difference occurs in Ni due to segregation, a difference in etching property occurs, and as a result, the smoothness of the etching wall surface (the inner peripheral surface of the electron beam transmitting hole) deteriorates. Since the segregated portion is elongated in the rolling direction by rolling, holes with poor smoothness on the wall will continue in the rolling direction long, and when viewed obliquely through the mask, light will appear as streaks. is there.

The Ni segregation part looks like a streak pattern (called a striped structure) as shown in Fig. 1 when the cross section of the alloy sheet immediately before etching is etched with an aqueous ferric chloride solution. When analyzed by MA (X-ray microanalyzer), as shown in Fig. 2, the Ni concentration sharply changes from the surface to the back, and the streak pattern and the Ni deviation seen when the cross section is etched. You can see that the prayers correspond. The Ni concentration difference is the maximum value of the difference between adjacent peaks (high Ni concentration) and valleys (low Ni concentration) in the Ni concentration change curve measured in the thickness direction by EPMA. It is. Conventionally, the segregation rate in the Ni segregation zone, that is, the rate of change of the Ni concentration in the segregation zone with respect to the Ni concentration in the base material, is reduced to 10% or less to prevent the occurrence of this uneven streaking. It has been proposed that the area be 5% by volume or less and the length of one segregated area immediately before etching be 3 Omm or less (Japanese Patent Application Laid-Open No. 60-56053). It has also been proposed to reduce the Ni concentration difference in the micro bias in the cross section of the alloy material immediately before etching to 3% or less, and to specify the concentration difference of Mn, P, and Si at the same position (Japanese Patent Laid-Open No. Heisei 9 (1994) -207). 9 1 1 4 3 6 2 5).

However, as the fine pitch of the shadow mask has advanced, conventional measures have become insufficient, and further improvement is desired. Therefore, an object of the present invention is to provide a Fe—Ni-based alloy for a shadow mask which can suppress the occurrence of streaks even in a recent fine pitch shadow mask, and an object of the present invention. Overview of the invention

The present inventors have conducted intensive studies in order to solve the above-mentioned problems. As a result, when the segregation of Ni in an alloy thin plate immediately before etching exceeds a predetermined level, the portion where Ni segregation occurs ( It has been found that reducing the number of Ni segregation zones per unit plate width is effective as a measure against uneven streaks. Of course, the streaks can be eliminated if there is no Ni segregation zone exceeding the predetermined degree.However, the present inventor has conducted repeated studies on the premise of the existence of the Ni segregation zone exceeding the predetermined degree. We have found that reducing the number of bands eliminates the problem of shadow mask quality.

That is, as described above, since the uneven streaks obliquely observe the light as if the etching wall surface of the transmission hole glows by tilting the shadow mask, the position of the Ni segregation zone in the plate thickness direction (depth) is constant. When the shadow mask is tilted at an angle of, it may not be visible as a stripe at the same time. In reality, the position (depth) in the thickness direction of the Ni segregation zone caused by micro-segregation during solidification is not constant, so if the existing density in the width direction of the Ni segregation zone decreases, it is detected as uneven streaks. You will not be able to.

In addition, the present inventors have determined that the distance between the main axes of dendrites in the ingot structure related to the size of microsegregation during solidification (hereinafter referred to as “primary dendrite arm's spacing”). ) Was found to be preferable. Because, if the distance between the main axes of dendrites is small, This is because the diffusion distance of Ni required for reducing segregation in processing and hot working can be short. Furthermore, the present inventors have clarified that in order to realize these, it is preferable to melt the ingot by electroslag remelting (ESR). In addition, it was clarified that the diameter of the ingot in that case is preferably 125 Omm or less. The present invention has been made based on the above findings. The Fe-Ni alloy for a shadow mask according to the present invention is: Ni: 30 to 50%, Mn: 0.5% or less by weight, balance Consists of Fe and unavoidable impurities, and is characterized by being produced by electroslag remelting (ESR).

According to the Fe-Ni alloy for shadow masks, the primary dendrite, arm, and spacing can be reduced because the alloy is melted by electroslag remelting, and thus Ni segregation. And the occurrence of stripe unevenness on the inner peripheral surface of the electron beam transmission hole can be suppressed.

Another Fe—Ni-based alloy for a shadow mask of the present invention is composed of Ni: 30 to 50%, Mn: 0.5% or less by weight, the balance being Fe and unavoidable impurities. In a cross section perpendicular to the rolling direction of the immediately preceding alloy sheet, the number of segregation zones having a Ni concentration difference of 0.7% or more is 1.0 or less per 100 mm in the sheet width direction.

Another Fe—Ni-based alloy for shadow masks of the present invention comprises, by weight, Ni: 30 to 50%, Mn: 0.5% or less, and the balance consisting of Fe and unavoidable impurities. The primary dendrite, arm, and spacing of the head is less than 1.00 mm.

Another Fe_Ni alloy for a shadow mask according to the present invention is, in terms of% by weight, Ni: 30 to 50%, Mn: 0.5% or less, and the balance consisting of Fe and unavoidable impurities. Electroslag remelting (ESR) in which the segregation zone with Ni concentration difference of 0.7% or more is less than 1.0 per 100mm in the width direction of the cross section perpendicular to the rolling direction of the thin alloy sheet It is characterized by being produced by

Another Fe-Ni alloy for a shadow mask according to the present invention is composed of Ni: 30 to 50%, Mn: 0.5% or less, and the balance of Fe and unavoidable impurities is ingot by weight. Primary dendrite 'arm spacing is less than 1.00mm The method is characterized by being produced by electroslag remelting (ESR). Next, the method for producing a Fe—Ni alloy for a shadow mask according to the present invention is as follows. 50%, Mn: 0.5% or less, the remainder is Fe-Ni-based alloy for shadow masks composed of Fe and unavoidable impurities, and the ingot diameter is 1250mm when melted by electroslag remelting (ESR). It is characterized as follows.

Another manufacturing method of the Fe—Ni-based alloy for a shadow mask according to the present invention is as follows. Ni: 30 to 50%, Mn: 0.5% or less in weight%, the balance being Fe and unavoidable impurities. In the section perpendicular to the rolling direction of the alloy thin plate immediately before etching, the segregation zone with a Ni concentration difference of 0.7% or more is 1.0 or less per 100 mm in the width direction of the shadow mask. When melting Ni-based alloys by electroslag remelting (ESR), the ingot diameter is reduced to 1250 mm or less. Another method for producing an Fe—Ni alloy for a shadow mask according to the present invention is as follows: Ni: 30 to 50%, Mn: 0.5% or less, with the balance being Fe and unavoidable impurities. In order to melt Fe-Ni-based alloys for shadow masks whose primary dendrite 'arm' spacing in the ingot is less than 1.00 mm by electroslag remelting (ESR), the ingot diameter should be 1250 mm or less. It is characterized by

Hereinafter, the reason for limiting the numerical values in the present invention will be described.

Ni content: If the Ni content is less than 30% or more than 50%, the thermal expansion coefficient becomes too large, and it is not possible to cope with a fine pitch shadow mask. Therefore, the content of Ni is set to 30 to 50%.

Mn content: When the Mn content exceeds 0.5%, the thermal expansion coefficient increases, so the Mn content was set to 0.5% or less.

Inevitable impurity elements include C, Si, P and S. It is desirable that C is 0.01% by weight or less, S U O. 1% by weight or less, P is 0.01% by weight or less, and S is 0.05% by weight or less.

Ni segregation zone in the section perpendicular to the rolling direction of the alloy sheet immediately before etching: Ni in the section perpendicular to the rolling direction of the alloy sheet immediately before etching. If the concentration difference exceeds 0.7%, the smoothness of the hole wall surface becomes poor when etching the shadow mask, which causes uneven streaks. Therefore, it is only necessary to define the existence density in the sheet width direction of the segregation zone in which the ^ 1 concentration difference exceeds 0.7%, and the Ni segregation band in which the Ni concentration difference is 0.7% or more in the sheet width direction. If it exceeds 1.0 per 100 mm, line irregularity will occur, so the number of Ni segregation zones with a Ni concentration difference of 0.7% or more per 100 mm in the sheet width direction is specified as 1.0 or less. .

Primary Dendrite in Arming 'Arm Spacing:

When the primary dendrite arm spacing in the ingot is less than 1.00 mm, the diffusion distance of Ni required for segregation reduction can be shortened, which is effective for eliminating uneven streaks. It was specified as 1.00 mm or less.

Melting method: primary dendrite in the ingot 溶 Electroslag remelting (ESR) or vacuum arc remelting (VAR) for laminating and solidifying can be considered as a melting method to reduce arm spacing. However, VAR is susceptible to large deviations due to abnormalities called white spots, so ESR is the preferred method of melting. However, since the solidified structure is inevitably coarsened as the ingot diameter increases even in ESR, the ingot diameter is set to 1250 mm or less, which can maintain the feature that the primary dendrite / arm / spacing is 1.00 mm or less. This ESR includes not only normal ESR but also ESR sealed with inert gas (usually Ar) and vacuum ESR (VSR). Brief explanation of drawings

FIG. 1 is a diagram showing a striped structure by corroding a cross section of a material.

FIG. 2 is a diagram showing the relationship between the depth from the surface of the material and the Ni concentration. Example

Next, the present invention will be described with reference to examples.

Vacuum ingots of 36% by weight of Ni, 0.25% by weight of Mn, and the remainder of Fe and inevitable impurities with diameters of 700, 1200 and 1500mm It was melted by dissolving in-place pouring and ESR. In order to remove the effect of the unsteady part of the ingot 'top, 20% was cut off from the top, and the remaining ingot was heated at 1250 ° C or more for 10 hours or more and forged to a thickness of 150 mm. After stripping, hot-rolled to a thickness of 3 mm, and then repeated cold rolling and annealing after pickling to finally produce a cold-rolled sheet with a thickness of 0.13 mm and a width of 600 mm.

The primary dendrite arm spacing of the ingot was sampled and measured at a position cut at 20% from the top. The cold-rolled sheet with a thickness of 0.13 mm was filled with resin so that the right-angle cross section of the whole width could be observed, mirror-polished, and etched with a 10-fold diluted solution of ferric chloride aqueous solution having a specific gravity of 45 mm. By doing so, the Ni segregation zone is corroded, and a striped structure as shown in Fig. 1 appears. After marking this Ni segregation zone with a dent of a picker hardness tester, it was mirror polished to the extent that the marking was not erased again, and the Ni concentration map of the segregation zone was analyzed using EPMA under the following conditions. Was measured. 5000x magnification

Acceleration voltage 20 kV

Dwe l l t i me 35ms

Dispersion crystal: L i F

Scan type beam

Step interval X: 0.19 / m, Y: 0.19 m

Number of steps X: 200 points, Y: 200 points

From the Ni concentration data obtained by the above measurement, the Ni concentration profile in the direction crossing the segregation zone as shown in Fig. 2 was obtained, and the Ni concentration difference between the peak and the valley of this Ni concentration profile was calculated as N The difference in Ni concentration in the i segregation zone was used. According to this method, the quantitative measurement accuracy is higher than that of the ordinary line analysis, and the measurement of the Ni concentration difference of 1% or less can be performed with high reliability. As described above, the Ni concentration difference of the Ni segregation zone existing at a plate width of 600 mm was measured, and the number of segregation zones with a concentration difference of 0.7% or more was converted to a value per 100 mm plate width. . Furthermore, each material was etched to create an actual shadow mask, and the streak quality was evaluated.

The primary dendrites of the ingots evaluated as described above, the arm spacing, and the number of segregation zones per 100 mm in width of the segregation zone with a Ni concentration difference of 0.7% or more in the cold rolled sheet. Table 1 shows the number and the streak quality of the mask for each ingot. As can be seen from Table 1, the No. 1 to No. 3 manufactured by the ESR method have a higher unevenness quality of the shadow mask than the No. 4 to No. 6 manufactured by the conventional vacuum melting and pouring method. Good.

In particular, manufactured with ingot diameter of 125 Omm or less, primary dendrite.Separation zone with arm spacing of 1.00 mm or less and Ni concentration difference of 0.7% or more per 100 mm of plate width. In No. 1 and No. 2 having a value of 1.0 or less, the line unevenness quality was very good. In contrast, in Comparative Examples No. 4 to No. 6, which were manufactured by the conventional vacuum melting one-shot pouring method, the primary dendrite arm spacing exceeded 1.00 mm regardless of the ingot diameter, and Ni The number of segregation zones with a concentration difference of 0.7% or more per plate width of 100 mm exceeded 10, resulting in poor linear streaks.

As described above, according to the present invention, it is possible to obtain a Fe—Ni-based alloy for a shadow mask capable of suppressing the occurrence of uneven streaks even with a recent fine-pitch shadow mask. The above effects can be obtained.

Ingot diameter Primary DAS + ΝίSegregation zone ** Number

No. Melting method Streaks quality Remarks

(mm) (mm) (pcs / 100mm)

1 ESR 700 0.35 0.0 Very good Example of the present invention

2 ESR 1200 0.90 0.6 Very good Example of the present invention

3 ESR 1500 1.30 1.4 Good Example of the present invention

4 VIM-place poured 700 1.20 10 or more *** Failure Comparative example

5 VIM-pour 1200 1.60 10 or more *** Failure Comparative example

6 VIM-Place pouring 1500 2.10 10 or more ** ★ Bad Comparative example

DAS: Dendrite 'arm' spacing

* Segregation zone with Ni concentration difference ≥0.7%

★ * ΝίBecause there are too many segregation zones with concentration difference ≥0.7%. The analysis was stopped after 10 samples.

Claims

The scope of the claims

1. By weight, Ni: 30 to 50%, Mn: 0.5% or less, the balance being Fe and unavoidable impurities, and characterized by being melted by electroslag remelting. Fe-Ni alloy for masks.

2. By weight%, Ni: 30 to 50%, Mn: 0.5% or less, the balance being Fe and unavoidable impurities. In the section perpendicular to the rolling direction of the alloy sheet immediately before etching, N An Fe—Ni alloy for shadow masks, wherein the number of segregation zones having an i concentration difference of 0.7% or more is 1.0 or less per 100 mm in the sheet width direction.

3. By weight%, Ni: 30-50%, Mn: 0.5% or less, the balance is composed of Fe and unavoidable impurities, and the distance between the main axes of dendrites in the ingot structure is 1.00 mm. A Fe-Ni alloy for shadow masks, characterized by the following.

4. By weight%, Ni: 30-50%, Mn: 0.5% or less, the balance being Fe and unavoidable impurities, and in a cross section perpendicular to the rolling direction of the alloy sheet immediately before etching, ^ ^ 1 For segregation zones with a concentration difference of 0.7% or more, 1.0 or less per 100 mm in the width direction of the sheet, produced by electroslag remelting (ESR). Ni-based alloy.

5. By weight%, Ni: 30 to 50%, Mn: 0.5% or less, balance of Fe and unavoidable impurities, and the distance between the main axes of dendrites in the ingot structure is 1. Fe-Ni-based alloy for shadow masks, characterized by being produced by electroslag remelting (ESR) with a size of 00mm or less.

6. By weight percent, Ni: 30-50%, Mn: 0.5% or less, Fe-Ni alloy for shadow mask consisting of Fe and unavoidable impurities by electroslag remelting. A method for producing Fe—Ni-based alloys for shadow masks, wherein the ingot diameter is reduced to 1250 mm or less when melting.

7. By weight%, Ni: 30 to 50%, Mn: 0.5% or less, the balance being Fe and unavoidable impurities. In the section perpendicular to the rolling direction of the alloy sheet immediately before etching, N When melting Fe-Ni alloys for shadow masks with less than 1.0 segregation zones with a concentration difference of 0.7% or more per 100 mm in the sheet width direction by electroslag remelting, The feature is that the diameter of the ingot is 1250mm or less. Of manufacturing Fe—Ni alloy for shadow masks.

8. By weight%, Ni: 30 to 50%, Mn: 0.5% or less, the balance being Fe and unavoidable impurities, and the distance between the main axes of dendrites in the ingot structure is 1. Fe-Ni alloys for shadow masks with a diameter of 00 mm or less are melted by electroslag remelting to reduce the ingot diameter to 125 Omm or less. Production method.

Claims of amendment

[9/9/2000 (09.12.00) Accepted by the International Bureau: Claim 1 at the time of filing was amended; other claims remain unchanged. (1 page)]

1. (After correction) In weight percent, Ni: 30 to 50%, Mn: 0.5% or less, the balance being Fe and unavoidable impurities, in a cross section perpendicular to the rolling direction of the alloy sheet immediately before etching. The segregation zone with a Ni concentration difference of 0.7% or more is 1.0 or less per 10 Omm in the plate width direction, and the interval between the main axes of dendrites in the ingot structure is 1.00 mm. A Fe-Ni alloy for shadow masks, characterized by the following.

2. By weight percent, Ni: 30-50%, Mn: 0.5% or less, the balance being Fe and unavoidable impurities. In the section perpendicular to the rolling direction of the alloy sheet immediately before etching,? ^ 1 Fe-Ni alloy for a shadow mask, wherein the segregation zone having a concentration difference of 0.7% or more is 1.0 or less per 100 mm in the sheet width direction.

3. By weight%, Ni: 30-50%, Mn: 0.5% or less, the balance being Fe and unavoidable impurities, and the distance between the main axes of dendrites in the ingot structure is 1. Fe—Ni-based alloy for shadow masks, characterized in that it is not more than 00 mm.

4. By weight%, Ni: 30-50%, Mn: 0.5% or less, the balance consisting of Fe and unavoidable impurities. In the cross section perpendicular to the rolling direction of the alloy sheet immediately before etching, N Fe-N for shadow masks characterized by being melted by electroslag remelting (ESR), with less than 1.0 segregation zones with a concentration difference of 0.7% or more per 100 mm in the plate width direction. i-based alloy.

5.Weight%, Ni: 30-50%, Mn: 0.5% or less, the balance consists of Fe and unavoidable impurities, and the distance between the main axes of dendrites in the ingot structure is 1. Fe-Ni-based alloy for shadow masks, which is less than 00mm and is produced by electroslag remelting (ESR).

6. Fe-Ni alloy for shadow masks consisting of Ni: 30 to 50%, Mn: 0.5% or less, the balance being Fe and unavoidable impurities in weight%, by electroslag remelting A method for producing Fe-Ni-based alloys for shadow masks, wherein the ingot diameter is reduced to 1250 mm or less when melting.

7. By weight%, Ni: 30-50%, Mn: 0.5% or less, the balance consisting of Fe and unavoidable impurities. In the cross section perpendicular to the rolling direction of the alloy sheet immediately before etching, N i Fe-Ni alloy for shadow masks with less than 1.0 segregation zones with a concentration difference of 0.7% or more per 100 mm

-11-Amended paper (Article 19 of the Convention)

Statements based on Article 19 of the Convention Claim 1 corresponds to JP 61-1 3746 and has been amended to include the features of claims 2 and 3. Claim 2 is that, at a cross section perpendicular to the rolling direction of the alloy sheet immediately before etching, the number of segregation zones having a Ni concentration difference of 0.7% or more is 1.0 or less per 100 mm in the sheet width direction. It is characterized by. On the other hand, JP 10-8213 only disclosed that the fluctuation of the concentration of Ni should be 13% or less, but did not disclose the features of claim 2.

Claim 3 is characterized in that, in order to suppress the occurrence of uneven streaks, the interval between the main axes (primary dendrite arms) of dendrites in the ingot structure is 1.00 mm or less. In contrast, FIG. 3 of JP 11-80839 describes that the interval between dendrite arms is 1 mm or less. However, the dendrite arm spacing is not that of the ingot structure as defined in claim 3, but is after the ingot has been soaked and agglomerated. Moreover, it is not clear whether this is the distance between the primary dendrite arms or the distance between the secondary dendrite arms. Therefore, it cannot be said that the features of claim 3 are disclosed in JP 11-80839.

JP 10-82 13 only describes that the setting speed is evaluated based on the distance between the secondary dendrite arms, but does not describe the distance between the primary dendrite arms and the occurrence of uneven streaks. . In addition, none of the documents discloses that the diameter of the ingot is 1250 mm or less and the primary dendrite's arm spacing is 1 mm or less.