JP2001098345A - Fe-Ni alloy for shadow mask and method for producing the same - Google Patents

Abstract

(57) [Problem] To provide an Fe-Ni alloy for a shadow mask capable of suppressing the occurrence of streaks in an electron beam transmission hole in a fine pitch shadow mask. SOLUTION: In weight%, Ni: 30 to 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 thin plate immediately before etching, a segregation zone having a Ni concentration difference of 0.7% or more is 1% per 100 mm in the sheet width direction. 0.0 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for a shadow mask to be finely etched, and more particularly to a Fe-N material which suppresses the occurrence of uneven streaks when finely etched.
It relates to an i-based alloy.

[0002]

2. Description of the Related Art In recent years, a shadow mask for a color cathode ray tube has been recently manufactured from the viewpoint of color purity by using Fe--Ni having a small thermal expansion.
System alloys are often used. The electron beam transmission holes of the shadow mask are formed by fine etching,
The Ni-based alloy shadow mask has a disadvantage that a defect called a streak tends to occur when etched, as compared with a conventionally used mild steel shadow mask. The uneven streaks 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.

[0003] In the case of a Ni-Fe 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 having poor smoothness on the wall surface are long in the rolling direction, and when viewed obliquely through the mask, light appears as streaks.

[0004] When the cross section of the alloy thin plate immediately before etching is etched with an aqueous ferric chloride solution, the Ni segregated portion looks like a streak pattern (referred to as a striped structure) as shown in FIG. This streak part is converted to EPMA (X-ray microanalyzer)
As shown in FIG. 2, it can be seen that the Ni concentration sharply changes from the surface to the depth, and that the streak pattern seen when the cross section is etched corresponds to Ni segregation. The Ni concentration difference is the maximum value of the difference between the adjacent peak (high Ni concentration) and valley (low Ni concentration) of the Ni concentration change curve measured in the thickness direction by EPMA.

Conventionally, in order to prevent the occurrence of uneven streaks,
The segregation rate of the Ni segregation area, that is, the change rate of the Ni concentration in the segregation area with respect to the Ni concentration of the base material is set to 10% or less, the segregation part in a unit volume is set to 5% by volume or less, and the length of one segregation part immediately before etching is reduced. It has been proposed that the thickness be 30 mm or less (Japanese Patent Application Laid-Open No. 60-56053). It has also been proposed to reduce the Ni concentration difference of micro-segregation in the cross section of the alloy material immediately before etching to 3% or less and to define the concentration difference of Mn, P, and Si at the same position (Japanese Patent Laid-Open No. 9-14362).
5).

[0006]

However, as the fine pitch of the shadow mask advances, conventional measures have become insufficient, and further improvements are desired. Accordingly, an object of the present invention is to provide an Fe—Ni-based alloy for a shadow mask capable of suppressing the occurrence of streaks even in a recent fine pitch shadow mask, and a method of manufacturing the same.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and found that when the segregation of Ni in an alloy thin plate immediately before etching exceeds a predetermined degree, the segregation of Ni is reduced. It has been found that reducing the number of generated portions (hereinafter, referred to as 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 a predetermined extent. However, the present inventor has conducted repeated studies on the premise of the existence of a Ni segregation zone exceeding the predetermined extent.
It has been found that if the number of segregation zones is reduced, there is no problem in the quality of the shadow mask.

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

Further, the present inventors have proposed 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 spacing”). Has been found to be preferable. This is because if the distance between the main axes of the dendrites is small, the Ni diffusion distance required for reducing the segregation in the subsequent homogenization heat treatment or hot working can be reduced. 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, ingot diameter in that case is 1250m
It has been clarified that m or less is preferable.

The present invention has been made based on the above findings, and the Fe—Ni-based alloy for a shadow mask according to the present invention is:
In weight%, Ni: 30 to 50%, Mn: 0.5% or less,
The balance consists of Fe and inevitable impurities, and is characterized by being produced by electroslag remelting (ESR).

According to the above Fe-Ni alloy for shadow masks, the primary dendrite arm spacing can be reduced because it is melted by electroslag remelting, thereby suppressing the segregation of Ni. As a result, the occurrence of uneven streaks on the inner peripheral surface of the electron beam transmission hole can be suppressed.

Another Fe-Ni for shadow mask of the present invention
The system alloy is 30% to 50% by weight of Ni and 0.3% by weight of Mn.
5% or less, the balance being Fe and unavoidable impurities, and in a cross section perpendicular to the rolling direction of the alloy thin plate immediately before etching, a segregation zone having a Ni concentration difference of 0.7% or more is 1.0% per 100 mm in the sheet width direction. It is characterized by being less than or equal to the number.

Another Fe-Ni for shadow mask of the present invention
The system alloy is 30% to 50% by weight of Ni and 0.3% by weight of Mn.
5% or less, the balance being Fe and unavoidable impurities, and the primary dendrite arm spacing in the ingot is 1.00 mm or less.

Another Fe-Ni for shadow mask of the present invention
The system alloy is 30% to 50% by weight of Ni and 0.3% by weight of Mn.
5% or less, the balance being Fe and unavoidable impurities, and in a cross section perpendicular to the rolling direction of the alloy thin plate immediately before etching, a segregation zone having a Ni concentration difference of 0.7% or more is 1.0% per 100 mm in the sheet width direction. It is characterized by being produced by electroslag remelting (ESR).

Another Fe-Ni shadow mask of the present invention
The system alloy is 30% to 50% by weight of Ni and 0.3% by weight of Mn.
It is characterized by being produced by electroslag remelting (ESR) in which the primary dendrite arm spacing in the ingot is 5% or less, and the balance consists of Fe and inevitable impurities and the primary dendrite arm spacing is 1.00 mm or less.

Next, the Fe-N for shadow mask of the present invention is used.
The manufacturing method of the i-based alloy is as follows: Ni: 30 to 50% by weight.
%, Mn: 0.5% or less, with the balance being Fe-Ni-based alloy for shadow masks composed of Fe and inevitable impurities by electroslag remelting (ESR).
The ingot diameter is 1250 mm or less.

Another Fe-Ni for shadow mask of the present invention
The method of producing the base alloy is as follows: Ni: 30 to 50% by weight;
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 thin plate immediately before etching, a segregation zone in which the Ni concentration difference is 0.7% or more is 100 mm in the sheet width direction. When the Fe-Ni-based alloy for a shadow mask, which is 1.0 or less, is melted by electroslag remelting (ESR), the ingot diameter is 1250 mm or less.

Another Fe-Ni for shadow mask of the present invention
The method of producing the base alloy is as follows: Ni: 30 to 50% by weight;
Mn: 0.5% or less, the balance being Fe and unavoidable impurities, and electroslag remelting (ES) of an Fe-Ni-based alloy for a shadow mask having a primary dendrite arm spacing of 1.00 mm or less in an ingot.
R), the ingot diameter was 125
It is characterized in that it is set to 0 mm or less.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the above numerical values in the present invention will be described below. Ni content : Ni content is less than 30% or 50%
%, The thermal expansion coefficient becomes too large, making it impossible to cope with the fine pitch of the shadow mask. Therefore,
The content of Ni was 30 to 50%. Mn content : When the Mn content exceeds 0.5%, the coefficient of thermal expansion increases, so the Mn content is set to 0.5% or less. Note that C, Si, P and S can be cited as unavoidable impurity elements. C is 0.001% by weight or less,
Si is 0.1% by weight or less, P is 0.01% by weight or less, S
Is desirably 0.05% by weight or less.

Directly in the rolling direction of the alloy sheet immediately before etching
Ni segregation zone in square cross section : If the Ni concentration difference in the Ni segregation zone in the cross section perpendicular to the rolling direction of the alloy sheet immediately before etching exceeds 0.7%, the smoothness of the hole wall surface when etched into the shadow mask is reduced. It becomes worse and causes stripe unevenness. Therefore, the existence density of the segregation zone in which the Ni concentration difference exceeds 0.7% in the sheet width direction may be defined. If the number of pieces exceeds
Ni segregation zone having a concentration difference of 0.7% or more in the sheet width direction 10
The number per 0 mm was defined as 1.0 or less.

Primary Dendrite A in Ingot
Beam spacing : When the primary dendrite arm spacing in the ingot is 1.00 mm or less, the Ni diffusion distance required for segregation reduction can be shortened, which is effective for eliminating uneven streaks. Therefore, the primary dendrite arm in the ingot. -The spacing was specified to be 1.00 mm or less.

Melting method : Electroslag remelting (ESR) or vacuum arc remelting (VAR) for laminating and solidifying can be considered as a melting method for reducing the primary dendrite arm spacing in the ingot. However, since VAR is liable to cause large segregation due to an abnormality called a white spot, the melting method is preferably ESR. However, even in the ESR, the solidified structure is inevitably coarsened as the diameter of the ingot increases, so that the diameter of the ingot can maintain the characteristic that the primary dendrite arm spacing is 1.00 mm or less.
m or less. The ESR includes not only normal ESR but also ESR sealed with an inert gas (usually Ar).
And vacuum ESR (VSR).

[0023]

Next, the present invention will be described with reference to examples. Ni
Are 36% by weight, Mn is 0.25% by weight, and the balance is Fe and unavoidable impurities.
Each 1500 mm ingot was melted by a vacuum melting-place pouring method and an ESR method. In order to remove the influence of the unsteady part of the ingot top part, 20% was cut off from the top, and the remaining ingot was 10% above 1250 ° C.
It was heated for more than an hour and forged to a thickness of 150 mm. After peeling, hot rolling is performed to a thickness of 3 mm, then cold rolling and annealing are repeated after pickling, and finally a thickness of 0.13 mm and a width of 600 m are obtained.
m cold-rolled sheet.

The primary dendrite arm of the ingot
The spacing was measured by sampling at a position cut at 20% from the top. The cold-rolled sheet having a thickness of 0.13 mm was buried in a tree so that a cross section perpendicular to the whole width of the roll was observable, mirror-polished, and etched with a 10-fold diluted solution of ferric chloride aqueous solution having a specific gravity of 45 Baume. 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 the Vickers hardness tester, mirror polishing to the extent that the marking is not erased again,
The Ni concentration map of the segregation zone was measured using EPMA under the following conditions.

Magnification 5000 times Acceleration voltage 20 kV Dwell time 35 ms Dispersion crystal: LiF Scan type Beam Step interval X: 0.19 μm, Y: 0.19 μm Number of steps X: 200 points, Y: 200 points

A Ni concentration profile in a direction crossing the segregation zone as shown in FIG. 2 is obtained from the Ni concentration data obtained by the above measurement, and the Ni concentration difference between the peak and the valley of the Ni concentration profile is determined by the Ni concentration in the Ni segregation zone. Difference. According to this method, the quantitative measurement accuracy is higher than 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 in the Ni segregation zone existing at a plate width of 600 mm was measured, and the concentration difference was 0.7%.
The number of the above segregation zones was determined by converting the number per 100 mm of the sheet width. Further, each material was etched to produce an actual shadow mask, and the streak quality was evaluated.

One of the ingots evaluated as described above
NextDendrite arm spacing, cold rolled Ni
Table 1 shows the number of segregation zones having a concentration difference of 0.7% or more per plate width of 100 mm and the streak quality of the mask for each ingot. As can be seen from Table 1, No. manufactured by the ESR method. 1 to No. No. 3 is No. 3 manufactured by the conventional vacuum melting-place pouring method. 4-No. 6 is better in the shadow unevenness quality of the shadow mask.

In particular, the ingot diameter is manufactured to be 1250 mm or less, and the number of segregation zones having a primary dendrite arm spacing of 1.00 mm or less and a Ni concentration difference of 0.7% or more per 100 mm of plate width is obtained. N of 1.0 or less
o. 1 and No. In No. 2, the uneven streaks quality is very good. On the other hand, in Comparative Example No. manufactured by the conventional vacuum melting-place-pour method. 4-No. In No. 6, the primary dendrite arm spacing exceeded 1.00 mm irrespective of the ingot diameter, the number of segregation zones having a Ni concentration difference of 0.7% or more per 100 mm of plate width exceeded 10, and the uneven streak quality was poor. It became bad.

[0029]

[Table 1]

[0030]

As described above, according to the present invention,
Fe-N for shadow masks that can suppress the occurrence of uneven streaks even in recent fine pitch shadow masks
An i-type alloy can be obtained, and excellent industrial effects can be obtained.

[Brief description of the drawings]

FIG. 1 is a micrograph 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 a material and the Ni concentration.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomoji Mizuguchi 1-1-2, Shiroganecho, Hitachi City, Ibaraki Pref. Nippon Mining & Metals Co., Ltd. Technology Development Center (72) Inventor Akihiro Ito 4 Chazu-cho, Muroran-shi, Hokkaido Inside Japan Steel Works (72) Inventor Hitohisa 4th Chazu-cho, Muroran City, Hokkaido Inside Japan Steel Works, Ltd. (72) Inventor Kanade Ueda 4th Chazu-cho, Muroran City, Hokkaido Inside Japan Steel Works, Ltd. (72) Takahiro Kishimoto Hokkaido, Japan 4 Chazu-cho, Muroran City Japan Steel Works Co., Ltd. F-term (reference) 5C027 HH02 5C031 EE09

Claims (8)

[Claims] 1. Ni: 30 to 50% by weight, Mn:
An Fe-Ni-based alloy for a shadow mask, wherein 0.5% or less, the balance being Fe and unavoidable impurities, which is melted by electroslag remelting. 2. Ni: 30 to 50% by weight, 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 thin plate immediately before etching, a segregation zone having a Ni concentration difference of 0.7% or more is 1% per 100 mm in the sheet width direction. Fe-Ni alloys for shadow masks, wherein the number of Fe-Ni alloys is not more than 0.0. 3. Ni: 30 to 50% by weight, Mn:
An Fe-Ni-based alloy for a shadow mask, wherein 0.5% or less, the balance consists of Fe and inevitable impurities, and an interval between main axes of dendrites in an ingot structure is 1.00 mm or less. 4. In weight%, Ni: 30 to 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 thin plate immediately before etching, a segregation zone having a Ni concentration difference of 0.7% or more is 1% per 100 mm in the sheet width direction. 0.0 or less Fe-Ni alloys for shadow masks, which are produced by electroslag remelting (ESR). 5. Ni: 30 to 50% by weight, Mn:
0.5% or less, the balance being Fe and unavoidable impurities, and the distance between the main axes of dendrites in the structure of the ingot is 1.00 mm or less. Melting by electroslag remelting (ESR). Fe-Ni alloy for shadow masks. 6. Ni: 30 to 50% by weight, Mn:
In order to melt the Fe-Ni-based alloy for a shadow mask consisting of Fe and unavoidable impurities of 0.5% or less by electroslag remelting, the ingot diameter should be 12 or less.
A method for producing an Fe-Ni-based alloy for a shadow mask, wherein the thickness is 50 mm or less. 7. Ni: 30 to 50% by weight, 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 thin plate immediately before etching, a segregation zone having a Ni concentration difference of 0.7% or more is 1% per 100 mm in the sheet width direction. In melting the Fe-Ni-based alloy for shadow masks of not more than 0.0 by electroslag remelting, the diameter of the ingot was 1250 mm.
Fe-N for shadow mask, characterized by the following:
A method for producing an i-based alloy. 8. Ni: 30 to 50% by weight, Mn:
0.5% or less, the balance being Fe and unavoidable impurities, and the distance between the main axes of the dendrites in the ingot structure is 1.00 mm or less.
A method for producing an Fe-Ni alloy for a shadow mask, wherein the ingot diameter is 1250 mm or less when the Ni alloy is melted by electroslag remelting.