JPH05222451A - Production of ni-fe alloy - Google Patents

Abstract

PURPOSE:To remarkably improve the occurrence of striped irregularity at the time of photoetching by subjecting an ingot of an Ni-Fe alloy where the contents of carbon, sulfur, and oxygen as impurities are regulated to specific values or below, respectively, to soaking treatment. CONSTITUTION:An ingot of an Ni-Fe alloy having a composition containing, by weight, <=0.005% C, <=0.003% S, and <=25ppm oxygen is heated and soaked up to a temp. between 1150 deg.C and the melting point and held for at least 3hr or more to undergo soaking treatment where Ni and Mn are sufficiently dispersed. This ingot is rolled into an extra thin alloy foil of about 0.15mm thickness and this foil is pierced by photoetching, by which a shadow mask is produced. By this method, the shadow mask excellent in etching characteristics, such as the uniformity of etching pits and the uniformity of etching velocity, and minimal in the occurrence of striped irregularity can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a Ni-Fe alloy used for a shadow mask mainly used for cathode ray tubes for large-sized televisions and displays.

[0002]

36 Ni-F known as Amber alloy
Iron alloys containing 20 to 60% Ni, such as e-based alloys, have an excellent low thermal expansion coefficient, and are therefore attracting attention as materials for shadow masks used in cathode ray tubes for color TVs, computer video displays, and the like. ing. Especially for color TVs and video displays, social demands for higher definition are increasing. This is because thermal expansion due to temperature rise due to electron beam collision is small compared to the conventionally used shadow mask made of mild steel, and therefore inconvenience such as image color misregistration is small.

[0003]

However, this N
When a shadow mask made of an i-Fe alloy is manufactured by punching an ultrathin alloy band having a thickness of about 0.15 mm by photoetching, streaks, creases, and creases (representatively referred to as streaks) are used. A so-called defect may occur. This streak is a phenomenon in which the diameter or shape of the holes punched by photoetching is uneven in the form of streaks. Therefore, it cannot be used as a shadow mask. Conventionally, the existence of non-metallic inclusions has been cited as one of the causes of this streaking, and careful selection of starting materials and reduction of inclusions by various refining methods have been studied. However, although these have the effect of reducing streaks, they are not satisfactory.

On the other hand, in Japanese Examined Patent Publication No. 61-23864 or Japanese Examined Patent Publication No. 63-64514, it is considered that the cause of streaking is Ni micro-segregation and the former is Ni-.
The Fe-based alloy ingot is heated at a temperature of 850 ° C. or higher and a melting point or lower, and the heat treatment is performed for 1 heat or 2 heats or more and the cross-section reduction rate is 40% or more. After melting in a gas furnace or the like, hot rolling at 1150 ° C to make a plate with a thickness of 5 mm, and then appropriately heat-treating at 1100 ° C for 1 hour or more to eliminate the Ni microsegregation, respectively. . These methods have not been able to completely eliminate the streak, and the low product yield has caused a high cost, which has hindered the widespread use of shadow masks of Ni—Fe alloys, and therefore further improvements have been desired.
An object of the present invention is to provide a method for producing a Ni—Fe based alloy capable of significantly improving the streak unevenness during photo-etching of the conventional Ni—Fe based alloy shadow mask.

[0005]

Means for Solving the Problems The inventor has conducted extensive research to eliminate this streak, and the cause of the streak is a fine linear or chain-like non-metallic inclusion that is spread in the rolling direction. Furthermore, it was found that the segregation of Ni, Mn, etc. causes a microscopic difference in the photoetching property, and as a result, it looks like streaks with the naked eye. More specifically, even if it is an ultrafine linear or chained non-metallic inclusion with a width of 2 μm and a length of about 250 μm, it will be used when the dot pitch becomes about 0.20 mm like the shadow mask used for high definition cathode ray tubes. Turns out to be a problem. Such types of fine nonmetallic inclusions that cause streaking include linear nonmetallic inclusions such as manganese silicate, manganese oxide, manganese sulfide, calcium aluminate, and iron oxide, and alumina, zirconia, and the like. There are chain-like non-metallic inclusions.

Of the above non-metallic inclusions, except for manganese sulfide, all are oxides, and the present invention reduces manganese sulfide and minimizes the number of oxides, while reducing the amount of Ni and Mn. N that eliminates segregation and at the same time reduces the C content from the viewpoint of photoetching rate.
The present invention relates to a method for manufacturing an i-Fe alloy. That is, the present invention is to soak a Ni-Fe alloy ingot containing C, 0.005% or less of S, 0.003% or less of C, 0.003% or less of oxygen, and 25 ppm or less of oxygen content as impurities, respectively, in weight%. It is a method for producing a characteristic Ni-Fe alloy.

[0007]

The Ni-Fe alloy as used in the present invention is an Fe-based alloy containing at least 20 to 60% Ni, and the alloy strip is limited to those used for shadow masks. To be done. However, if Ni is in the above range, it is added to deoxidize or strengthen the alloy, for example, S
Other elements such as i, Mn, Mg, B, Cr, Mo and V may be included. The reasons for limiting each element will be described below.

If the content of C exceeds 0.005%, the etching rate becomes extremely slow and not only the productivity is significantly hindered, but also the streaking is likely to occur, so the upper limit as an impurity is limited to 0.005%. If S exceeds 0.003% as an impurity, the amount of sulfide-based non-metallic inclusions increases, which causes uneven streaks. Therefore, the upper limit of S is limited to 0.003%. As described above, oxygen is a main constituent element of the linear or chain-shaped non-metallic inclusions as an impurity and causes streaking when photo-etching the alloy strip. Therefore, the upper limit is set to 25 ppm.

As described above, the ingot of the Ni--Fe alloy in which the contents of C, S and oxygen as the impurity elements are limited is Ni.
Soaking treatment is performed in order to sufficiently diffuse Mn and Mn at high temperature. In the above-mentioned Japanese Patent Publication No. 61-23864, the ingot is heated for a short time for casting, but according to the present invention, the ingot is heated to a temperature of at least 1150 ° C. or higher and a melting point or lower to obtain the ingot size. Depending on the condition, for example, when the diameter is 300 mm or more, a diffusion process is required in which sufficient time is maintained for at least 3 hours after soaking. In addition, the aforementioned Japanese Patent Publication No. 63-
In No. 64514, the thickness was hot rolled at 1150 ° C.
It is disclosed that after forming a 5 mm plate, the diffusion treatment of Ni is performed by heat treatment at 1100 ° C. for 1 hour or more. However, since the surface area of a plate material is extremely large in the high temperature treatment, it is necessary to generate a large amount of an oxide layer or to perform heat treatment in a special atmosphere, which requires a large amount of cost and equipment.

According to the present invention, since the soaking treatment is performed at the stage of the ingot, it has a small surface area and can be carried out in the atmosphere if an antioxidant or the like is applied, which is economically advantageous. As described above, according to the present invention, the contents of C, S and oxygen in the Ni—Fe alloy are limited to specific amounts or less, respectively, and the ingot is subjected to a soaking treatment, so that the uniformity of pores at the time of etching is not increased. In addition, it is possible to provide a shadow mask that has excellent etching properties such as uniformity of etching rate and that minimizes the occurrence of streaking.

The present invention will be described below with reference to examples.
First, charge a vacuum induction melting furnace with a low C, low S iron source, and
After charging i, melted in vacuum and then decarburized,
Then deoxidize by adding a deoxidizer, and then cast in vacuum to cast a steel ingot with C: 0.004%, S: 0.002% and oxygen content of 20 ppm, and then soaking at 1280 ° C. After the treatment, forging and rolling, and the cold rolling, the occurrence state of the crevices in the 0.15 mm thick steel strip was investigated. In addition, Table 1 shows Comparative Steels 2 to 4 including other compositions and the occurrence of streaking when no soaking treatment is performed.

[0012]

[Table 1]

In Table 1, No. 1 is the steel of the present invention,
Both S and O are low, and no streaking occurs when soaking treatment is performed, but as in Nos. 2, 3, 4, and 5, S,
If either of the values of O is high or if the soaking process is not performed, a streak pattern is generated due to the above reason. Therefore, it is possible to prevent the occurrence of streaking for the first time by reducing both S and O and performing the soaking process. Note that, regarding C, it is necessary to make extremely low C in relation to etching efficiency, and it is not directly related to occurrence of streaking.

[0014]

As described above, not only the C, S, and O are lowered, but also the soaking process is performed in the state of the ingot to reduce the segregation, and the etching rate is excellent, and the high quality 36Ni without streaks is obtained. -Fe based alloys and other N
Since it is possible to produce an i-Fe alloy, it is possible to stably supply a good quality shadow mask material,
Its industrial significance is great.

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Claims (1)

[Claims] 1. A soaking treatment is performed on a Ni—Fe alloy ingot containing C 0.005% or less, S 0.003% or less, and an oxygen content of 25 ppm or less, which are impurities such as carbon, sulfur, and oxygen in weight%. A method for producing a characteristic Ni-Fe alloy.