KR930007092B1 - Method of making a shadow mask - Google Patents

Abstract

The Fe-Ni alloy for a shadow mask of the color TV is produced by (a) casting, hot rolling, acid-cleaning and cold-rolling an alloy of 0.001-0.004 wt.% C, 0.02-0.06 wt.% Si, 0.2-0.35 wt.% Mn, at most 0.001 wt.% P, at most 0.001 wt.% S, 32-36 wt.% Ni, Fe and impurities, (b) tempering it in the hydrogen crucible for 3 hr, and (c) annealing it at 900-1100 deg.C for 15-30 min. The alloy has a good press-moldability and tensile strength.

Description

Manufacturing method of Fe-Ni alloy material for shadow mask

FIG. 1 is an optical micrograph (100 times magnification) showing the growth state of crystal grains on a surface before heat treatment of a Fe-Ni alloy material for shadow mask (hereinafter referred to as "Fe-Ni alloy material").

2 (a) to 2 (c) are optical micrographs (100 times magnification) showing the growth state of crystal grains of the Fe-Ni alloy material after annealing heat treatment in a vacuum furnace at 900 ° C, 1000 ° C and 1100 ° C, respectively. .

3 (a) to 4 (c) show the crystal grains of the Fe—Ni alloy material of the present invention after annealing heat treatment in a furnace (hereinafter referred to as “hydrogen”) in a hydrogen atmosphere of 900 ° C., 100 ° C. and 1100 ° C., respectively. Optical micrograph (magnification 100 times) showing growth state.

4 is a graph showing the results of tensile strength tests of annealing heat treatment of the Fe—Ni alloy material in a hydrogen furnace (the present invention) and an annealing heat treatment of a vacuum furnace (a conventional method) according to the ambient temperature.

The present invention relates to a method for producing a Fe-Ni alloy material for shadow masks, and more particularly, to a method for heat-treating Fe-Ni alloy materials for shadow masks to be suitable for use as shadow masks for color televisions.

In color television, the shadow mask is a component that allows the R, G, and B beams emitted from the electron gun to pass through the aperture so that each electron beam can be accurately landed with the corresponding phosphor formed inside the screen. The amount of electron beams is approximately 35%, and the rest acts as a heat source that hits the shadow mask body and heats it.

The temperature of the shadow mask heated by the radiation collision of the electron beam is about 80 ° C, and the shadow mask causes the phenomenon of shadowing due to the temperature rise at this time, resulting in a decrease in color purity.

Attempts have been made to produce shadow masks as materials having a low coefficient of thermal expansion in order to suppress the shadowing of the shadow masks described above. As such a material, an alloy which hardly expands regardless of the temperature rise due to the radiation collision of the electron beam is used, and an alloy whose thermal expansion coefficient is almost zero is used. For example, an Invar alloy such as an Invar alloy (36Ni-Fe), a super invariant steel (Ni-5Co-63Fe), a stainless invariant steel (54Co-9.Cr-36.5Fe), and a 43Pd-57Fe alloy is used.

Conventionally, a steel sheet obtained by vacuum melting a 36Ni-64Fe alloy, for example, into a steel sheet by casting, annual rolling, pickling, cold rolling, annealing, cold rolling, and the like to manufacture an alloy material for a shadow mask. In order to impart press formability, the steel sheet was placed in a hydrogen kiln for aluminum kilg steel, and heated for 2 hours, and kept at a peak temperature of 700 ° C for 10 minutes.

1 is an optical micrograph showing the shape of the crystal grains of the steel sheet at this time.

This photograph shows that the nonuniformity of grain growth in the thickness direction of the steel sheet, that is, the grain growth at the surface layer portion of the steel sheet is insufficient. It is assumed that such nonuniform grain growth is caused by the degree of segregation of impurities in the thickness direction of the steel sheet.

In addition, since the grain growth insufficient at this surface layer portion is related to the yield strength of the steel sheet, the press formability of the steel sheet is deteriorated.

Yield strength should be 24Kg / mm ² or less for good press formability. As a result of measuring the mechanical properties of this sheet, the tensile strength is 47Kg / mm ² and the yield strength is 36Kg / mm ² . It was confirmed that the press formability of the film was poor.

Therefore, in order to make the grain growth uniformly in the inside of the steel sheet and in the surface layer portion, that is, to improve the press formability of the steel sheet, the annealed steel sheet is placed in a vacuum furnace and warmed for 3-4 hours, and the peak temperature is 1150 ° C. The method of making the grains of the inside of the steel sheet and the surface layer part grow uniformly by holding for 15 minutes at is also performed.

As a result, yield strength is ²⁴ Kg / mm <^2> or less and favorable press formability is obtained.

The present inventors earnestly studied the Fe-Ni alloy material for shadow mask in order to solve the above problems, and as a result of adding a small amount of alloying elements such as P and S to the Fe-Ni alloy steel to produce a steel sheet in a conventional manner, The present invention has been completed by discovering that even when the steel sheet is heat-treated only once in a hydrogen furnace at 900 ° C.-1100 ° C., mechanical properties superior to those obtained by heat treatment in a conventional vacuum furnace can be obtained.

An object of the present invention is to manufacture a Fe-Ni alloy material for shadow mask, the problem of the above-described conventional method is solved to simplify the process, low manufacturing cost and manufacture of Fe-Ni alloy material for shadow mask having excellent mechanical properties To provide a way.

In the present invention, the weight% C: 0.01-0. 004, Si: 0.2-0. 06, Mn: 0.2-0. 35, P and Si: 0.001 or less, Ni: 32-36, remainder: Fe and an unavoidable impurity of alloy material made of steel sheet by casting-hot rolling-pickling-cold rolling-annealing and cold rolling In the manufacturing method of the Fe-Ni alloy material for shadow mask which consists of annealing this steel sheet, in order to give favorable press formability, the said annealing heat treatment puts the said steel sheet into a hydrogen furnace and heated it for 3 hours. It provides a method for producing a Fe-Ni alloy material for shadow mask, characterized in that for 15 minutes to 30 minutes at a peak temperature of 900-1100 ℃.

When the annealing heat treatment temperature in the hydrogen furnace is less than 900 ℃, grain growth of the Fe-Ni alloy material is not enough, and when it exceeds 1100 ℃ grain growth is excessive and the energy cost is high, so the temperature range of the annealing heat treatment in the hydrogen furnace is It is preferable that it is 900 degreeC-1100 degreeC. In addition, if the holding time at the peak temperature is 15 minutes or less, the grain growth of the Fe-Ni alloy material is nonuniform, and if it exceeds 15 minutes, grain growth becomes excessive, yield strength is lowered, and mechanical properties are lowered. It is preferable that time is 15 minutes-30 minutes.

According to the present invention, when the alloy material is heat treated at 900 ° C.-1100 ° C. in a hydrogen furnace, P and S contained in the Fe—Ni alloy material are evaporated to promote grain growth, and Mn is uniformly coated on the surface. It is thought to originate from being distributed and producing favorable blackening film.

Hereinafter, the present invention will be described in detail as a preferred embodiment.

EXAMPLE

Cast alloy material consisting of C: 0.03%, Si: 0.03%, Mn: 0.3%, P and S: 0.008%, Ni: 34%, balance: Fe and unavoidable impurities as weight percent. Hot-rolled-pickling-cold-rolled-annealed-cold-rolled to a steel sheet having a thickness of 0.1 mm, the steel sheet thus obtained was put in a hydrogen furnace, heated for 3 hours, and maintained at a peak temperature of 1000 DEG C for 20 minutes. The Fe-Ni alloy material (b) for shadow mask of this invention was obtained. Further, except that the annealing heat treatment in the hydrogen furnace was 900 and 11000 ° C., the same procedure as described above was performed to obtain alloy materials (a) and (c) for Fe-Ni for shadow mask, respectively.

Comparative Example

Except for replacing the annealing heat treatment in a hydrogen furnace with the annealing heat treatment in a vacuum furnace, the rest of the process was performed in the same manner as in the above embodiment to obtain a Fe-Ni alloy material for the shadow mask. The annealing heat treatment at a degree of vacuum was performed at 900, 1000, and 1100 ° C., respectively, (a) ', (b)', and (c) '.

The optical micrographs of the grain growth states of Examples (a), (b) and (c) of the present invention and (a) ', (b)', and (c) 'of the comparative examples (3) A) to 3 (c) and 2 (a) to 2 (c) are shown, respectively. Through this photo, the Fe-Ni alloy material of the present invention subjected to the annealing heat treatment in the hydrogen furnace was confirmed that the crystal grains were uniformly grown in the same way as the conventional method, that is, the annealing heat treatment in the vacuum furnace, so that the press moldability was improved.

In addition, (a), (b) and (c) of the present invention and (a) ', (b)' and (c) 'of the comparative examples were subjected to a tensile test at room temperature, 80 ℃ and 200 ℃ atmosphere temperature The results are shown in FIG. In FIG. 4, A is a test result at room temperature, B at 80 ° C, and C at 200 ° C. It can be seen from Fig. 4 that the Fe-Ni alloy material for shadow masks of the present invention subjected to annealing heat treatment in a hydrogen furnace has better tensile strength than that of the conventional method of heat treatment in a vacuum furnace.

Table 1 shows the results of testing the spring back of the Fe-Ni alloy material of the present invention and the Fe-Ni alloy material of the conventional method by molding with a shadow mask.

TABLE 1

In Table 1, the vacuum is a Fe-Ni alloy material of the conventional method subjected to annealing heat treatment in a vacuum furnace (1100 ℃), hydrogen means annealing heat treatment in a hydrogen furnace (1100 ℃), H and V are horizontal and vertical, respectively It represents. It can be seen from Table 1 that the Fe-Ni alloy material of the present invention has a smaller springback effect than the conventional case ④ when the working condition (temperature, Gop) of the molding die is appropriate.

In conclusion, it is confirmed that the Fe-Ni alloy material for shadow mask of the present invention has superior press formability and excellent tensile strength than that of the conventional method.

Claims (1)

A method for producing a Fe-Ni alloy material for shadow masks, comprising casting, hot rolling, pickling, and cold rolling of a Fe-Ni alloy material, wherein the weight% is C: 0.001-0. 004, Si: 0.0-0. 06, Mn: 0.2 ~ 0. 35, P and S: 0.001 or less, Ni: 32 to 36, other balance: alloy material of Fe and unavoidable impurities is cast-hot rolled-pickling-cold rolled, put into a hydrogen furnace and heated for 3 hours And maintaining the annealing process for 15 minutes to 30 minutes at a peak temperature of 900-1100 ° C. for producing a Fe-Ni alloy material for shadow masks.

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