JP2003321750A - HIGH STRENGTH, LOW THERMAL EXPANSION Fe-Ni-Co BASED MATERIAL FOR SHADOW MASK AND SHADOW MASK - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material for a shadow mask which consists of an Fe-Ni- Co based alloy having high strength and a low thermal expansion coefficient, and to provide a shadow mask. <P>SOLUTION: The Fe-Ni-Co based material for a shadow mask has a composition containing, by mass, 31 to 34% Ni, 3.5 to 6% Co, >0.1 to 0.5% Nb, <0.01% C and 0.004 to 0.01% N, and the balance substantially Fe. The content of B can be controlled to ≤0.004%. Preferably, the maximum particle diameter of niobium compounds observed in the cross section of the structure is <0.5 μm, and the number thereof is ≥50,000 pieces/mm<SP>2</SP>. Alternatively, the material for a shadow mask is produced by performing rolling as well, and the degree of aggregation in the ä100} of the rolled surface is 60 to 90%. The shadow mask consists of the material for a shadow mask. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Fe-Ni-Co-based shadow mask material having high strength and a small average coefficient of thermal expansion, and particularly to a color cathode ray tube used for a television monitor, a computer monitor or the like. The present invention relates to a shadow mask material suitable for high definition and flat screen, and a shadow mask.

[0002]

2. Description of the Related Art A shadow mask incorporated in a color cathode ray tube has an opening for allowing an electron beam emitted from an electron gun to pass therethrough, so that the electron beam accurately strikes a phosphor inside a glass panel. It has a role as an electron beam selection mechanism. In this case, when the shadow mask is locally heated by the electron beam that does not pass through the aperture of the shadow mask and is deformed into a dome shape due to thermal expansion, mislanding of the electron beam occurs due to such a doming phenomenon. In order to prevent this doming, the material is Fe-36 having a small coefficient of thermal expansion.
% Ni based amber alloys have been used.

In recent years, the technical trend of color cathode-ray tubes is toward higher definition, and a material having a lower thermal expansion than that of an amber alloy has been required as a material for a shadow mask. In addition, since the radius of curvature of the shadow mask increases due to the flattening of the screen, and this structurally significantly reduces the mechanical strength of the shadow mask, the conventional amber alloy lacks the drop resistance, and the cathode ray tube manufacturing process. Deformation of the shadow mask due to impact during transportation and transportation was a problem.

Here, the predetermined curvature of the shadow mask is
It is applied by press molding, and before that molding, annealing (mask annealing) for improving press moldability is usually performed. The mask annealing is generally performed after etching perforation, but the above-mentioned problem is largely due to the strength after the mask annealing.

For these problems, Fe-31% Ni, which has a lower thermal expansion coefficient and higher strength than Amber alloy, is used.
The use of -5% Co-based Super Invar alloy is expanding. However, since the Super Invar alloy contains expensive Co, thinning the plate for cost reduction,
To achieve this, higher strength is needed.

[0006] Such Fe-, which is used for the above-mentioned applications,
For Ni—Co alloys, as a means for improving the strength, many methods have been proposed for adding IVa and Va group elements in the periodic table such as Nb. For example, Japanese Patent Laid-Open No. 2001-34
No. 2546 has 1 to 3.5% Co for low thermal expansion.
In addition to adding 0.1% or less of Mn content and 0.1% to 4% of Nb, Zr, Ti and V in order to improve the drop strength, the Young's modulus is improved. .

In Japanese Patent Laid-Open No. 2002-80939, the Mn content is set to 0.1% or less, and Co is optionally 0.01 to 2
%, A low thermal expansion is achieved and Nb, T
The yield strength and Young's modulus are increased by adding 0.01 to 0.8% of a and Hf. The applicant of the present invention has disclosed that
No. 01-262278, low thermal expansion was achieved by optimizing Ni and Co amounts within a Co addition range of 22% or less, and Nb was 0.005 to 0.1%, and N was 0.00.
A method has been proposed in which a granular precipitate containing Nb is finely precipitated by adding 2 to 0.02% to increase the strength.

[0008]

The method described above is an effective means for increasing the strength of the shadow mask. However, JP 2001-342546 A and JP 2002-8093 A
The method of No. 9 uses Nb or the like in a solid solution state to achieve high strength, and therefore a large amount of Nb needs to be added to further increase strength, resulting in deterioration of thermal expansion characteristics and coarseness. There is concern about crystallization of Nb carbonitride.

In addition to the strength as the shadow mask, the material for the shadow mask is required to have a strength capable of coping with further thinning, that is, handleability.
Here, when the strength of the shadow mask is increased, its press-formability becomes a problem, but with respect to this, press-molding is possible even to some extent with a high-strength material due to recent improvements in press-molding technology.

Therefore, the present invention is based on a shadow mask using a Super Invar alloy, can be used for further thinning, and can maintain a sufficient strength even after the mask annealing. Small expansion coefficient F
a shadow mask material made of an e-Ni-Co alloy,
And it aims to provide a shadow mask.

[0011]

The present inventor has studied various methods for increasing the strength of a shadow mask material, and has found that the optimum combination of the alloying elements constituting the shadow mask material and preferably the microstructure control are performed. The inventors have found a method capable of achieving high strength without deteriorating low thermal expansion characteristics, and have reached the present invention.

That is, according to the present invention, Ni:
31-34%, Co: 3.5-6%, Nb: over 0.1-
0.5%, C: less than 0.01%, N: 0.004 to 0.
This is a high-strength, low-thermal-expansion Fe-Ni-Co-based shadow mask material, characterized in that 01%, and the balance substantially consisting of Fe. Preferably, the maximum particle size of the niobium compound observed in the tissue cross section is less than 0.5 μm, and the number is 500.
It is a high-strength, low-thermal expansion Fe-Ni-Co-based shadow mask material characterized in that the number is 00 / mm ² or more.

In addition, the high strength and low thermal expansion F of the present invention
The e-Ni-Co-based shadow mask material is a shadow mask material produced by rolling, and the rolling surface has a {100} aggregation of 60 to 90%. For the shadow mask material of the present invention, B is 0.00
It may be 4% or less.

The high strength and low thermal expansion F of the present invention
A shadow mask made of an e-Ni-Co-based shadow mask material, which is thin and excellent in strength, and has achieved high-precision and high-precision etching hole processing.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The feature of the present invention is that Fe--Ni--C.
For strengthening o-based alloys, C as a solid solution strengthening element
O and Nb are utilized, and further, by finely depositing a niobium compound (carbonitride of Nb) in the structure, the grain refinement and precipitation strengthening are simultaneously utilized. Due to the synergistic effect of these strengthening methods,
High strength can be achieved without degrading the low thermal expansion characteristics of the Fe-Ni-Co alloy.

First, the inventor of the present invention, in the Fe-Ni-Co type alloy, influences on the strength and thermal expansion coefficient of Co and N.
The effects of b and N were investigated in detail, and the optimum composition balance for each characteristic was examined.

First, the balance of Ni and Co components will be described. In the Fe-Ni-Co alloy, the coefficient of thermal expansion becomes minimum when the (Ni + Co) content is around 37%. On the other hand,
The yield strength at room temperature is greatly affected by the amount of Co and is the same (Ni + C
If the amount is o), the higher the amount of Co, the higher the yield strength. As a result of detailed investigations based on these findings, the Co content was determined to be 3.
It was found that adjusting the amount of Ni to 5% or more and the amount of (Ni + Co) to be about 37% is an effective component balance for achieving both low thermal expansion properties and high strength properties as a shadow mask material. did.

However, when the Co content exceeds 6%, the Ni content needs to be adjusted to less than 31% in order to maintain the low thermal expansion property, but when the Ni content is less than 31%, the martensitic transformation temperature of the alloy is lowered. Rises to −60 ° C. or higher, and there is concern that the shadow mask may be deformed when used in cold regions. Therefore, the Fe-Ni-Co-based shadow mask material of the present invention has Ni: 31 to 34% and Co: 3.5 to 6% as a result of also considering the balance between Ni and Co.

Next, Nb and N will be described. Nb is
For the present invention, it is an important element for achieving high strength, and as the amount of addition increases, the strength can be increased by solid solution strengthening. Further, by simultaneously adding nitrogen, niobium carbonitride can be finely precipitated in the structure, and it is possible to achieve high strength by both the action of refining crystal grains and precipitation strengthening.

In the present invention, in order to stably obtain the above-mentioned high strength action, it is necessary to add Nb in excess of 0.1%. That is, even when the Nb amount is 0.1% or less,
Although it is possible to increase the strength to some extent by refining the crystal grains by fine precipitation of niobium carbonitride, higher strength is required for thinning applications of 0.12 mm or less, which is peculiar to shadow mask materials. If
If the Nb content is 0.1% or less, the strength is insufficient. In the present invention, in order to utilize the high-strength effect that also utilizes solid solution strengthening,
It is important to add Nb in excess of 0.1%.

Here, since Nb is an element that increases the thermal expansion coefficient of the alloy, the material for the shadow mask of the present invention, in which the balance between Ni and Co is also important for achieving both low thermal expansion characteristics and high strength characteristics, is particularly important. In, the mutual examination of the components is necessary. The effect of Nb on the coefficient of thermal expansion is
Compared to addition to ordinary Invar alloy, addition to Super Invar alloy is smaller, and if Fe-Ni-Co based alloy satisfying the composition balance of Ni and Co of the present invention, Nb addition to some extent. Even with this, excellent strength can be achieved while keeping the thermal expansion coefficient small. However, if Nb is added in excess of 0.5%, the coefficient of thermal expansion becomes large, and the surface is easily oxidized during heat treatment such as mask annealing. Therefore, the amount of Nb was set to 0.5% or less.

Nitrogen (N) is also an essential element for the present invention. In the niobium compound in the structure used for strengthening of the present invention, it is particularly effective to use niobium nitride whose fine adjustment is possible. That is, since niobium nitride has a small solubility product ([% Nb] · [% N]), its nitride precipitates with the addition of an extremely small amount of Nb as compared with niobium carbide. It becomes possible to deposit a fine niobium compound which is effective for miniaturization.

In the case of the present invention, if the amount of nitrogen is less than 0.004%, it is difficult to obtain sufficient strength because the above-mentioned niobium compound is insufficiently precipitated. However, the amount of nitrogen is 0.0
If it exceeds 1%, it becomes difficult to control the crystal orientation, the strength is reduced due to the crystal orientation, and the high nitrogen material itself is difficult in terms of the nitrogen addition technology, and the yield also deteriorates. It was set to 0.01% or less. Therefore, in the present invention, the nitrogen content needs to be 0.004 to 0.01% in terms of the component balance with Nb and other Co and Ni.

C is also an element whose adjustment is important in achieving the present invention. If the amount of C is too large, a coarse niobium compound (Nb
(Carbide) to crystallize and reduce the amount of fine niobium compound (Nb nitride) that is effective for refining crystal grains.
Less than%.

In the present invention, B is preferably added. B strengthens the crystal grain boundaries and is effective in improving hot workability. It is also effective in controlling the crystal orientation after recrystallization and improving the press formability after mask annealing. However, if a large amount of B is contained, the formation of fine niobium compounds is hindered by bonding with N, so the content is preferably 0.004% or less.

In addition, regarding the composition of the Fe—Ni—Co-based shadow mask material of the present invention, Si: 0.1
% Or less (preferably 0.05% or less), Cr: 0.1%
Hereinafter, Mn is preferably 0.1% or more, more preferably 0.2% or more. In addition, the total of other elements not described is preferably 0.1% or less.

As described above, the shadow mask material of the present invention utilizes the fine adjustment of the niobium compound in the structure to achieve its high strength. In order to achieve this, it is important to adjust the component composition of the material. In particular, we examined the size of the niobium compound that is effective in achieving high strength by refining the crystal grains.

In the Fe-Ni-Co-based shadow mask material of the present invention, it is desirable that the average grain size, which is effective for increasing the strength, be 10 or more according to JIS G 0551. In this case, Zener
(R = ^4/3 · r / f ^2/3 : average crystal grain size R of matrix, average grain size r of precipitate, volume fraction f of precipitate)
From the relationship between the dispersed particle size derived from the above and the average crystal grain size of the matrix, the maximum particle size of the niobium compound observed in the tissue cross section was set to less than 0.5 μm, and the number
It is desirable that the number is 0 pieces / mm ² or more.

Therefore, in the Fe-Ni-Co-based shadow mask material of the present invention, the maximum grain size of the niobium compound observed in the cross-sectional structure is set to less than 0.5 μm and the number thereof is set to 5
It is preferable to set it to 0000 pieces / mm ² or more. In addition,
The ultrafine niobium compound having a particle size of less than 0.5 μm can be adjusted, for example, by appropriately adjusting the conditions of the soaking solution treatment and the precipitation treatment at 900 to 1350 ° C. in the manufacturing process. And, in such a state of the niobium compound, substantial change does not occur by mask annealing, and it is possible to achieve a structure in which the average crystal grain size is 10 or more in the grain size number even after the mask annealing. .

As a method for measuring the particle size of the niobium compound observed on the cross section of the structure, for example, a method of observing the niobium compound appearing on the corroded structure surface by the SPEED method can be applied. Fig. 1 shows Fe-Ni-C corroded by the SPEED method.
The textured surface of the o-based alloy was observed with a scanning electron microscope at a magnification of 16000, showing a niobium compound having a maximum grain size of 0.09 μm. Regarding the total number of these niobium compounds occupying the tissue cross section, the number observed on the tissue surface may be counted and converted into the number per mm ² . In the case of FIG. 1, it is 1388 × 10 ⁴ pieces / mm ² .

The Fe-Ni-Co-based shadow mask material of the present invention may be produced through a rolling process so as to serve as a thin plate, and the orientation of crystal planes gathering on the rolling surface at that time is controlled. It is preferable. For a thin plate, cold rolling and recrystallization annealing are appropriately repeated to finish to a predetermined plate thickness.
Since b is added, a rolling texture is easily formed,
After recrystallization, the degree of integration of the {100} plane on the rolled surface increases.

In this case, the high etching rate {10
When the {0} planes are gathered on the rolled surface, the etching factor can be improved, so that highly precise and highly accurate etching holes can be formed in the etching perforation in the next step. Therefore, in the present invention, it is desirable that the degree of {100} aggregation of the rolled surface be 60% or more.

However, if the {100} aggregation is excessively large, the etching progresses along the crystal lattice, so that the etching holes have a non-uniform shape. In addition, the size of the Schmid factor changes depending on the crystal orientation to be assembled, and the number of slip systems activated at the same time when a stress is applied is different, and if the degree of integration of {100} faces exceeds 90%. Since the strength is also reduced, the {100} integration degree is preferably 90% or less.

[0034]

[Examples] Steel ingots of Fe-Ni-Co alloys adjusted to the various components shown in Table 1 were produced in a vacuum induction melting furnace.
After that, it was heated to 1250 ° C. for solution treatment, and subsequently heated to 1100 ° C. forging and hot rolling to obtain a plate material having a thickness of 2.5 mm. 650-700 ℃ on this plate
After the precipitation treatment of the niobium compound was performed, cold rolling and annealing were repeated to obtain a cold rolled material having a thickness of 0.1 mm. In addition, No. Reference numeral 11 corresponds to a normal Super Invar alloy.

These finished cold rolled materials were used as test materials,
The maximum particle size, number, and crystal orientation of the niobium compound were measured. The particle size of the niobium compound was measured by measuring the total area of the observation field of view of the textured surface of the test material corroded by the SPEED method.
It was performed by observing 00 μm ² with a scanning electron microscope. As the number of niobium compounds, the number observed on the same tissue plane was counted. The degree of {100} aggregation on the rolled surface was obtained from the following mathematical formula by subjecting the test material to X-ray diffraction.

{100} Aggregation (%) = I (200) /
{I (111) + I (200) + I (220) + I (311)} ×
100 * I (hkl): peak intensity in X-ray diffraction of crystal plane (hkl)

Then, after annealing these test materials at 850 ° C., which corresponds to mask annealing, the average crystal grain size (crystal grain size number according to JIS G 0551) of each test material was 0. The 0.2% proof stress and the thermal expansion coefficient were measured.
0.2% proof stress at 20 ℃, coefficient of thermal expansion 20 ~ 10
It was measured in the range of 0 ° C. Table 1 shows the above measurement results.

[0038]

[Table 1]

No. which satisfies the present invention. 1 to 10 are Co,
It contains Nb and N in an appropriate amount and has a thermal expansion coefficient of No. 11
(Compared to normal Super Invar alloy) Since a yield strength higher than that of No. 11 by about 20% or more has been obtained, it is possible to reduce the plate thickness by about 10%. In particular, No. 1 with a large amount of Co. 4 or No. 4 having a large amount of Nb. No. 6 had a very high yield strength of 360 MPa. No. In No. 7, the degree of {100} aggregation exceeds 90%, and although the Nb amount is large, the strength is slightly low, but it has reached a sufficient strength.

On the other hand, No. When the amount of N is large like 12,
Since the {100} aggregation is high, it becomes difficult to obtain strength. In addition, the manufacturing yield was reduced. No. In No. 13, the niobium compound (niobium nitride) was insufficiently precipitated due to the small amount of nitrogen, and the grain size was made finer and the strengthening by precipitation strengthening was insufficient.

Further, No. 1 satisfying the present invention. 1-10 is
It was confirmed that even after the mask annealing, there was substantially no change in the state of the niobium compound, and even before the annealing, it showed excellent strength.

[0042]

According to the present invention, it is possible to provide an Fe-Ni-Co based shadow mask material having high strength and a small thermal expansion coefficient. Therefore, the deformation in this application can be prevented and the handling is facilitated, so that it is possible to further thin the plate and the cost of the shadow mask can be reduced.

[Brief description of drawings]

FIG. 1 is a metal microstructure photograph showing a niobium compound observed on the textured surface of an Fe—Ni—Co alloy.

Claims (5)

[Claims] 1. In mass%, Ni: 31 to 34%, C
o: 3.5-6%, Nb: over 0.1-0.5%, C:
Less than 0.01%, N: 0.004 to 0.01%, the balance substantially consisting of Fe, high strength low thermal expansion Fe-Ni-Co based shadow mask material. 2. The maximum particle size of the niobium compound observed in the tissue section is less than 0.5 μm, and the number is 50000 /
The material for a high-strength low-thermal expansion Fe—Ni—Co-based shadow mask according to claim 1, wherein the material is ² mm ² or more. 3. A shadow mask material produced by rolling, the rolling surface of which has a {100} aggregation of 60.
% To 90%, The high-strength, low-thermal expansion Fe-Ni-Co-based shadow mask material according to claim 1 or 2. 4. The high strength low thermal expansion Fe—Ni—Co based shadow mask material according to claim 1, wherein B: 0.004% or less by mass%. 5. A shadow mask comprising the material for a shadow mask according to any one of claims 1 to 4.