KR20040094358A - HIGH STRENGTH Fe-Ni-Co ALLOY FOR SHADOW MASK AND MANUFACTURING METHOD THEREOF - Google Patents

Abstract

PURPOSE: To improve falling strength of a Fe-Ni-Co alloy without addition of elements for high strengthening. CONSTITUTION: In a Fe-Ni-Co alloy that contains 30 to 35 mass% of Ni, 2 to 8 mass% of Co, 0.50 mass% or less of Mn, and the balance of Fe and inevitable impurities or accompanying elements including 0.10 mass% or less of C, 0.10 mass% or less of Si, 0.05 mass% or less of Al, 0.005 mass% or less of S and 0.005 mass% or less of P and is constructed in a rolling work structure, the high strength Fe-Ni-Co alloy for shadow mask is peculiar to that a recrystallization structure consisting of a grain size number of 9.5 or more is revealed when the Fe-Ni-Co alloy is annealed at 750 deg.C for 15 minutes, and a recrystallization structure consisting of a grain size number of 8.5 or more is revealed when the Fe-Ni-Co alloy is annealed at 850 deg.C for 15 minutes.

Description

High-strength Fe-Ni-CO-based alloy for shadow mask and its manufacturing method {HIGH STRENGTH FE-Ni-CO ALLOY FOR SHADOW MASK AND MANUFACTURING METHOD THEREOF}

According to the present invention, even if the shape of the electron beam transmitting portion of the shadow mask is pressed to be completely flat, it is excellent in deformation resistance due to drop impact in the state of being mounted on the CRT and low thermal expansion in which doming does not occur. The present invention relates to an alloy thin ribbon for a flat mask that can be maintained, wherein the Fe-Ni-Co alloy thin ribbon for the flat mask improves the drop impact deformation resistance by controlling the annealing softening characteristics and maintains low thermal expansion. It is about.

In a color CRT, a screen is displayed by making the electron beam shot from the electron gun touch the fluorescent substance inside a glass panel. It is the deflection yoke that controls the direction of the electron beam by magnetic force. In front of the glass panel, a mechanism for dividing the electron beam into pixels so as to contact a predetermined phosphor is formed. Such a mechanism is called a mask or a color screening mechanism. The mask for a color CRT tube is a shadow mask method for etching a mask material into a dot shape or a slot shape and then press-molding, and an aperture that is applied by applying a strong tensile force up and down to the frame material after etching in a lattice shape. It is roughly classified as an aperture-grille method. Each method has one set, and both methods are used in the market.

However, many attempts have been made to develop flat screens for flattening the display screen. Herein, the flat screen is a conventional spherical display screen having a flat shape that is almost completely. One of the big problems when trying to flatten a CRT's screen is how to use shadow masks or aperture grilles to get flat. Although each faced a challenge, making the surface of the shadow mask close to flat by pressing is basically more difficult than that of the most advanced method such as Aperture Grill (eg, NIKKEI ECTRONICS., 1999.7. 26 (No.748) p. 128).

This is because, since the shadow mask is manufactured by press-molding a metal sheet, it is necessary to maintain the shape by self-holding force unlike the most method, and basically, the shape cannot be maintained unless it is spherical. . On the other hand, since the flat mask makes the mask almost flat, it is difficult to maintain the shape. In order to solve this problem, there is no method other than increasing the strength of the mask. Unlike the meaning of the strength of a general metal (for example, strength by a tensile test), the term "mask strength" refers to whether or not deformation of the mask occurs by imparting the entire CRT after the CRT is assembled. Specifically, the CRT is dropped at a certain height to test whether the mask is deformed. It is necessary for flat tubes to develop a mask that is strong against such impact deformation, that is, improved drop resistance (hereinafter referred to as drop strength).

In addition, the flat tube is required to have excellent doming characteristics. In short, as the mask becomes flat in the spherical surface, the angle of incidence of the electron beam emitted from the electron gun at the four corners of the mask becomes an acute angle. In other words, this means that the electron beam collides erroneously only by a slight misalignment of the mask due to thermal expansion, thereby causing a color deviation problem. This requires the development of a low thermal expansion mask that is significantly lower in thermal expansion than a conventional mask.

Although not intended as a flat mask, in an attempt to improve thermal expansion characteristics and impact resistance, Japanese Patent No. 2723718 discloses a shadow mask using a Fe-Ni-Co-based alloy (Super Invar) containing 2 to 7% by mass of Co. It is proposed to lower the coefficient of thermal expansion by However, only by containing 2-7 mass% of Co could not bear the drop impact when the mask after performing an annealing process before press was flat. In addition, in Japanese Patent No. 1854642, one or two or more of Ti, Zr, B, Mo, Nb, N, P, and Cu are 0.01 to a total of Fe-Ni alloy having Ni of 34 to 38 mass%. Although it is proposed to contain 1.0 mass% to prevent buckling due to the impact at the time of granulation, the coefficient of thermal expansion exceeds 10 × 10 ⁻⁷ / ° C. and the color when the mask is made flat. It was not satisfactory from the standpoint of suppressing the deviation.

The shadow mask material is obtained by casting an alloy material of a predetermined composition into a ingot after solvent in a vacuum induction melting furnace (VIM furnace), for example, hot rolling and cold rolling after forging, and then bright annealing. And cold rolling are repeated, and finally cold rolling is carried out by a rolling roll which is less dull to a predetermined thickness in the range of 0.05 to 0.3 mm. As for the plate | board thickness of the various shadow mask materials manufactured by an etching process, 0.05-0.30 mm is common, The material of plate | board thickness 0.1-0.13 mm is used especially for the press mask type flat mask. Subsequently, the material for shadow mask is obtained by slitting to a predetermined plate width. After degreasing, the shadow mask material is coated with photoresist on both sides, baked (printed), developed, and then etched and processed, and then individually cut to form a shadow mask material unit.

The shadow mask material unit is annealed at a temperature of 700 ° C. or higher in a non-oxidizing atmosphere, for example, a reducing atmosphere, and endowed with press formability. In the pre-annealing method, the annealing is performed on the final cold rolled material before etching. After the leveler processing, it is molded into a flat mask by pressing.

Finally, the flat mask press-molded is subjected to a blackening treatment in the air or a CO / CO ₂ gas atmosphere after degreasing to form a black oxide film on the surface. The press-molded "flat mask" of the present invention has an almost complete planar shape, for example, having an outer surface curvature radius R of 100,000 mm or more and a plan view (maximum height / effective screen diagonal dimension of the screen curved portion) of 0.1% or less. will be.

An object of the present invention is to improve the drop strength of a Fe—Ni—Co alloy without adding an element for high strength.

As a result of intensive studies to solve this problem, the inventors have found that the drop strength of the shadow mask has a very good correlation with the proof stress. After annealing before press molding, Fe-Ni-Co-based alloys were optimized to obtain high yield strength, and at the same time, a manufacturing method for the same was disclosed.

In short, the present invention

(1) Ni: 30-35 mass%, Co: 2-8 mass%, Mn: 0.50 mass% or less, and remainder Fe and an unavoidable impurity or accompanying element (C: 0.10 mass% or less, Si: 0.10) Mass% or less, Al: 0.05% or less, S: 0.005% or less by mass, P: 0.005% or less by mass), and a Fe-Ni-Co-based alloy composed of a rolled structure. When the annealing is performed, recrystallized tissue having a crystal grain size number of 9.5 or more is expressed, and when the annealing is performed at 850 ° C. for 15 minutes, the recrystallized tissue having a crystal grain size number of 8.5 or more is expressed. Ni-Co alloy,

(2) a high strength Fe-Ni-Co-based alloy for shadow mask according to the above (1), wherein the tensile strength is 630 MPa or more;

(3) The slab is hot rolled, cold rolling and recrystallization annealing is repeated, and finally manufactured by the process of cold rolling, the crystal grain size number is adjusted to 8.0 or more in annealing before final cold rolling, and final cold The workability of rolling shall be 30% or more, The manufacturing method of the high strength Fe-Ni-Co-type alloy for shadow masks of said (1) and (2).

(4) The slab is hot rolled, cold rolled and recrystallized annealing is repeated, and finally, it is manufactured by the process of performing cold rolling, and the crystal grain size number is adjusted to 8.0 or more by annealing before final cold rolling, and final cold The workability of rolling shall be 50% or more, The manufacturing method of the high strength Fe-Ni-Co-type alloy for shadow masks of said (1) and (2) characterized by the above-mentioned.

(5) The high-strength Fe-Ni-Co system for shadow masks of (3) and (4) above, characterized in that the (200) plane X-ray diffraction intensity composition ratio is adjusted to 90% or less during annealing before final cold rolling. Manufacturing method of alloy,

It is about.

Embodiment of the invention

The reason for limitation of this invention is described below.

(1) About Ni and Co

Ni content of the Fe-Ni-Co system alloy bath in this invention is 30-35 mass%. Moreover, Co content is the range of 2-8 mass%.

When Ni content is less than 30 mass% or more than 35 mass%, a thermal expansion coefficient will become large and it is unsuitable for shadow masks.

Co reduces the thermal expansion and at the same time contributes to the improvement of the yield strength after recrystallization. For this reason, it is necessary to add 2 mass% or more, but when the amount exceeds 8 mass%, the magnetic properties deteriorate, so the range of 2 to 8 mass% Is added.

(2) Mn, impurities and accompanying elements

a) C content

When C exceeds 0.10 mass%, etching permeability is impaired by formation of carbides, and an alloy bath becomes unsuitable as a shadow bath for shadow mask. Therefore, the upper limit of C content was set to 0.10 mass%.

b) Si content

When Si exceeds 0.10 mass%, the alloy casting is not suitable as a shadow mask casting because the etching permeability is impaired. Therefore, the upper limit of Si content was set to 0.10 mass%.

c) Al content

When Al exceeds 0.05 mass%, formation of an alumina type interference | inclusion becomes remarkable and the etching permeability of an alloy bath is impaired. Therefore, the upper limit of Al content was set to 0.05 mass%.

d) Mn content

Mn is contained in the iron-based alloy in order to make S harmless to hot workability. If the content is small, sufficient effect cannot be obtained. However, when exceeding 0.5 mass%, an alloy bath will harden and the workability will fall. Therefore, the upper limit of Mn content was set to 0.5 mass%. Preferably, addition in the range of 0.05 to 0.5 mass% is recommended.

e) S content

When S exceeds 0.005 mass%, the hot workability of a bath is remarkably inhibited. Therefore, the upper limit of S content was set to 0.005 mass%.

f) P content

When P exceeds 0.005 mass%, the alloy bath will inhibit the etching permeability and will become unsuitable as the shadow mask casting tank. Therefore, the upper limit of P content was set to 0.005 mass%.

(3) Recrystallization characteristics

Since the drop strength has a correlation with the proof strength in the shadow mask state, it is required to have a high yield strength after performing annealing treatment at 700 to 950 ° C before press molding. In order to express the desired strength, when the annealing of 750 degreeC and 15 minutes is carried out, the recrystallized structure whose crystal grain size number is 9.5 or more generate | occur | produces, and when the annealing of 850 degreeC and 15 minutes is carried out, the recrystallized structure whose crystal grain size number is 8.5 or more This should be a Fe-Ni-Co-based alloy to be generated, and when the recrystallization characteristic deviates from this specification, sufficient drop strength as a shadow mask is not obtained.

(4) About tensile strength

The recrystallization characteristics correlate with the tensile strength of the material (finished final rolling). If the tensile strength is 630 MPa or more, the recrystallization characteristics described above can be obtained.

(5) About annealing before final rolling and final rolling work

In the present invention, the above-described recrystallization characteristics are imparted to the Fe—Ni—Co alloy by crystal grain refinement during annealing before final rolling and steel processing in the final rolling process. That is, the desired recrystallization characteristic can be obtained by performing steelwork rolling of 30% or more of workability in the state of the fine grain whose crystal grain size number obtained by annealing before final rolling is 8.0 or more. If the workability of the final rolling process is less than 30%, the desired recrystallization characteristics cannot be obtained. Therefore, in this invention, crystal grain size number obtained by annealing before final rolling is prescribed | regulated as 8.0 or more, and the workability of a final rolling process is 30% or more. More preferable final rolling workability is 50% or more.

The crystal grain size number is measured in accordance with the method specified in JIS G 0551. In addition, rolling work degree (R) is defined by the following formula.

R = {(t ₀ -t) / t ₀ } × 100%

Where t is the thickness after rolling and t _{0 is} the thickness before rolling

(6) About (200) plane X-ray diffraction intensity component ratio in annealing before final rolling

In this invention, in the annealing before final rolling, the (200) plane X-ray diffraction intensity component ratio is adjusted to 90% or less. The (200) plane X-ray diffraction intensity component ratio is defined by the following equation.

(200) Plane X-ray diffraction intensity composition ratio = I ₂₀₀ / (I ₁₁₁ + I ₂₀₀ + I ₂₂₀ + I ₃₁₁ ) x 100 (%)

In the above formula, I _hkl represents the X-ray diffraction intensity of the (hkl) lattice plane. The (200) plane X-ray diffraction intensity component ratio in the annealing before final rolling affects the properties of the final rolled material. That is, when the (200) plane X-ray diffraction intensity component ratio exceeds 90%, work hardenability decreases. For this reason, when (200) plane X-ray-diffraction intensity composition ratio exceeds 90%, tensile strength will become low even if steel processing is performed by final rolling. Since the tensile strength correlates with the recrystallization property, when the tensile strength decreases, the desired recrystallization property is not obtained. Therefore, the (200) plane X-ray diffraction intensity component ratio is adjusted to 90% or less.

The definition of the (200) plane X-ray diffraction intensity component ratio includes the (111) plane, the (200) plane, the (220) plane, and the (311) plane as the diffraction grating plane. This is because these four diffraction grating planes are the main diffraction grating planes of the Fe-Ni-Co-based alloy targeted in the present invention.

X-ray diffraction intensity (cps) is measured by the commonly used X-ray diffractometer. The tube uses Co tube. The measurement of the X-ray diffraction intensity (cps) includes a method of determining the height of the peak and a method of determining the integral value of the peak. In this invention, the integral value of a peak is calculated | required.

(Example)

In manufacture of the shadow mask material shown in the Example, the slab of a predetermined chemical composition was prepared first, hot rolling was performed, the oxidation scale of the surface was removed, and the board of thickness 3mm was obtained. Herein, the impurity concentration satisfies C: 0.10% by mass or less, Si: 0.10% by mass or less, Al: 0.05% by mass or less, S: 0.005% by mass or less, and P: 0.005% by mass or less. Both Examples and Comparative Examples were satisfied. The composition was adjusted in the range of 31-33 mass% of Ni, 4.5-5.5 mass% of Co, and 0.2-0.4 mass% of Mn. In addition, reinforcing elements, such as Nb, were not added, For example, the analytical value of Nb was less than 0.01 mass%.

The obtained hot rolled sheet having a thickness of 3 mm was processed in the next step to obtain a product having a thickness of 0.12 mm.

Hot rolled sheet → Annealing → Middle annealing → Middle rolling → Annealing before final rolling → Final rolling

Here, all the annealing is recrystallization annealing, and all the rolling other than hot rolling is cold rolling. The processing conditions or the target quality in each process are as follows.

(1) small rolling

The plate | board thickness which finishes by the small rolling was set inversely from the intermediate rolling process degree, the final rolling process degree, and the plate | board thickness of a product.

(2) intermediate annealing and intermediate rolling

In order to obtain a predetermined (200) plane X-ray diffraction intensity composition ratio (%) in the annealing before the final rolling, the crystal grain size number in the intermediate annealing and the workability in the intermediate rolling must be set to a predetermined one. In the example of this invention, the crystal grain size number in the intermediate annealing was set to 8.0, and the workability of the intermediate rolling was set to 72%.

(3) annealing before final rolling

The annealing temperature and the annealing time were controlled to obtain an annealing material having a crystal grain size number of 9.0 in the example of the present invention.

(4) final rolling

The plate thickness was rolled to 0.12 mm to make a product.

TABLE 1

Table 1 shows the characteristics of the invention example and the comparative example.

The surface strength before final rolling annealing (200) in Table 1 was calculated | required by the following formula as a composition ratio (%) of (200) surface diffraction X-ray intensity measured in the state which finished annealing before final rolling.

(200) Plane diffraction X-ray intensity composition ratio = I ₂₀₀ / (I ₁₁₁ + I ₂₀₀ + I ₂₂₀ + I ₃₁₁ ) x 100 (%)

Here, I _hkl represents the X-ray diffraction intensity of the (hkl) lattice plane. The intensity (cps) of diffraction X-rays was measured by an X-ray diffraction analyzer. As the district, Co district was used. In the measurement of diffraction X-ray intensity (cps), the integrated value of the peaks was determined. As a pretreatment of the measurement sample, the surface layer was removed by chemical polishing (etching). The surface layer is removed in order to remove the influence of the deteriorated layer formed on the surface. The amount removed was 5% of the plate thickness. The removal amount of 5% is set after confirming the distribution of the (200) strength inside the plate thickness.

The tensile strength before annealing represents the tensile strength (MPa) of a 0.12 mm thick product. A product crystal grain size (750 degreeC) shows the crystal grain size after the heating test (750 degreeC x 15 minutes: non-oxidizing atmosphere) of a 0.12 mm-thick product. A product crystal grain size (850 degreeC) shows the crystal grain size after the heating test (850 degreeC x 15 minutes: non-oxidizing atmosphere) of a 0.12 mm-thick product. The annealing strength after annealing is 0.2 after a 0.12 mm thick product is subjected to heat treatment (8% H ₂ -N ₂ , dew point 0 ° C., 800 ° C. × 15 minutes) assuming annealing performed before press molding the shadow mask. % Yield strength (MPa).

Inventive Examples Nos. 1 to 5 have a product crystal grain size (750 ° C.) of 9.5 or more, and a product crystal grain size (850 ° C.) of 8.5 or more, and have a high strength after heat treatment assuming annealing before press molding.

On the other hand, in Comparative Example 1, since the intermediate rolling workability is as high as 78%, the (200) plane diffraction X-ray intensity constitution ratio in the annealing before final rolling exceeds 90% of the claims. Moreover, the crystal grain size in the annealing before final rolling is also below 8.0 which is a claim. For this reason, in Comparative Example 1, the tensile strength before annealing, the product crystal grain size (750 ° C.), and the product crystal grain size (850 ° C.) deviate from the claims, and have a low strength after heat treatment assuming annealing.

In addition, the final rolling workability of the comparative example 2 does not satisfy the claim. For this reason, in Comparative Example 2, the tensile strength before annealing, the product crystal grain size (750 ° C.), and the product crystal grain size (850 ° C.) deviate from the claims, and have a low strength after heat treatment assuming annealing.

In Comparative Example 3, the (200) plane diffraction X-ray intensity composition ratio in the annealing before the final rolling, the crystal grain size number in the annealing before the final rolling, and the rolling workability in the final rolling all satisfy the claims. Not. As a result, in Comparative Example 3, the yield strength after heat treatment assuming annealing is the lowest value among all the examples.

In the Fe-Ni-Co alloy, a shadow mask material having improved drop strength can be provided at low cost without impairing production efficiency without adding an element for high strength.

Claims (6)

Ni: 30-35 mass%, Co: 2-8 mass%, Mn: 0.50 mass% or less, and remainder Fe and an unavoidable impurity or accompanying element (C: 0.10 mass% or less, Si: 0.10 mass% or less) , Al: 0.05% by mass or less, S: 0.005% by mass or less), P: 0.005% by mass or less), and annealing was performed at 750 ° C. for 15 minutes in an Fe-Ni-Co alloy composed of a rolled structure. High-strength Fe-Ni-Co for shadow masks, wherein recrystallized tissues having a grain size number of 9.5 or more are expressed, and recrystallized tissues having a grain size number of 8.5 or more are expressed when annealing at 850 ° C. for 15 minutes. System alloy. The high-strength Fe-Ni-Co-based alloy for shadow mask according to claim 1, wherein the tensile strength is 630 MPa or more. After hot rolling the slab, repeating cold rolling and recrystallization annealing, finally, it is manufactured by the process of performing cold rolling, and the crystal grain size number is adjusted to 8.0 or more in the annealing before final cold rolling, and the final cold rolling processing A method for producing a high strength Fe-Ni-Co alloy for shadow masks according to claim 1 or 2, characterized in that the figure is 30% or more. After hot rolling the slab, repeating cold rolling and recrystallization annealing, finally, it is manufactured by the process of performing cold rolling, the crystal grain size number is adjusted to 8.0 or more in annealing before final cold rolling, and the final cold rolling is processed. A method for producing a high-strength Fe-Ni-Co alloy for shadow masks according to claim 1 or 2, characterized in that the figure is 50% or more. 4. The high strength Fe-Ni-Co system for shadow masks according to claim 3, wherein in the annealing before final cold rolling, the (200) plane X-ray diffraction intensity component ratio defined by the following equation is adjusted to 90% or less. Method of manufacturing the alloy. (200) Plane X-ray diffraction intensity composition ratio = I ₂₀₀ / (I ₁₁₁ + I ₂₀₀ + I ₂₂₀ + I ₃₁₁ ) x 100 (%) {Where I _hkl represents the X-ray diffraction intensity of the (hkl) lattice plane} The high-strength Fe-Ni-Co system for shadow masks according to claim 4, wherein in the annealing before final cold rolling, the (200) plane X-ray diffraction intensity composition ratio defined by the following equation is adjusted to 90% or less. Method of manufacturing the alloy. (200) Plane X-ray diffraction intensity composition ratio = I ₂₀₀ / (I ₁₁₁ + I ₂₀₀ + I ₂₂₀ + I ₃₁₁ ) x 100 (%) {Where I _hkl represents the X-ray diffraction intensity of the (hkl) lattice plane}