JPH03267320A - Production of shadow mask material - Google Patents

Abstract

PURPOSE:To lower softening temp. before spherical forming by means of a warm press by specifying draft in finish cold rolling in a method for subjecting an Fe-Ni low thermal expansion alloy plate to cold rolling, to recrystallization annealing, and then to cold rolling. CONSTITUTION:A hot rolled plate of an Fe-36%Ni alloy is used, and this plate is subjected to cold rolling at 92.5% draft, to recrystallization annealing at 850 deg.C for 1min, and then to finish cold rolling at 5-20% draft. By this method, even if softening temp. before pressing is as low as <800 deg.C, extremely remarkable effects on the coarsening of grains can be obtained and superior effects can be produced on work efficiency and economical efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a Fe-36%Ni based shadow mask material for color television picture tubes.

<Prior art and its problems> Conventionally, mild steel plates such as low carbon rimmed steel plates or low carbon A1 killed steel plates have been used for shadow masks for color television picture tubes, but in recent years Fe, which has lower thermal expansion characteristics than these materials, has been used. -36% NJ-based amber materials have also begun to be used.

The manufacturing process of the Fe-36%Ni based shadow mask is generally as follows. First, after melting, casting and hot rolling,
After appropriate cold rolling and recrystallization annealing or recrystallization annealing, a slight finish cold rolling is performed to produce a shadow mask material having a predetermined thickness. The material for the shadow mask is etched and perforated to create a flat mask. The flat mask is softened and annealed to give it press formability, and is then pressed into a spherical shape. The spherical mask is subjected to a blackening process to become a shadow mask.

However, Fe-36%Ni alloy has higher strength than mild steel plate, and shadow mask materials manufactured by cold rolling, recrystallization annealing, or slight finish rolling after recrystallization annealing of this alloy are Because of the problem of spherical formability after etching and perforation, softening annealing is performed at a temperature of 800° C. or higher to coarsen the crystal grains and soften the material before press forming. After this softening annealing, spherical shaping is performed by warm pressing at a temperature of around 200°C.

The conventional warm pre-public softening annealing.

It coarsens the crystal grains in order to soften the material. For this reason, for example, in JP-A No. 62-287044,
After 2-5% slight finish cold rolling before softening annealing, 8
However, even 800°C is a high temperature, and from the viewpoint of work efficiency and economic efficiency, softening annealing at a lower temperature than the current method is disclosed.
There has been a strong desire to develop a manufacturing method that can provide low strength equivalent to that of materials softened and annealed at temperatures above °C.

The present invention aims to provide a method for producing a low-strength shadow mask material with excellent press formability by performing softening annealing at a temperature of less than 800° C. before warm pressing.

<Structure of the Invention> The present invention uses a low thermal expansion alloy mainly composed of Fe and Ni as a base plate, and after performing cold rolling and subsequent recrystallization annealing, it is finished with a rolling reduction in the range of 5 to 20%. Provided is a method for producing a material for a shadow mask, which is characterized by cold rolling.

The reasons for limiting the conditions in the method of the present invention will be made clear in the detailed description of the invention.

<Specific disclosure of the invention> The contents of the present invention will be specifically explained below with reference to the drawings.

Figure 1 shows 9.
After 2.5% cold rolling, recrystallization annealing was performed at 850°C for 1 minute, and then
Finish cold rolling is performed at various rolling rates, and softening annealing is performed at 750°C for 60 minutes or at 830°C for 60 minutes before press forming.
The relationship between the finish cold rolling rate and the grain size number when the cold rolling was carried out for 0 minutes is shown.

From FIG. 1, the final cold rolling rate of the 830° C. softened and annealed material is 5%, and the final cold rolling rate of the 750° C. annealed material is 15%, and the grains are significantly coarsened.

As described above, the finishing cold rolling rate at which the grains become coarsest varies depending on the softening annealing temperature.

Therefore, by cold rolling a hot rolled sheet of Fe-36%Ni alloy, followed by recrystallization annealing, and then performing appropriate finish cold rolling, the softening annealing temperature before pressing can be lower than 800°C. It is possible to obtain a very remarkable effect on grain coarsening even at a temperature of .

On the other hand, 0.2% in the tensile test was used as the evaluation standard for pressability.
Yield strength is used as an indicator. 0.2% yield strength 1 at 200°C is sufficient for warm press forming at 200°C.
0 kg/mm” or less is desirable.

FIG. 2 shows the results of a warm tensile test conducted at an ambient temperature of 200° C. to determine the 0.2% proof stress. The samples used for the warm tensile test were prepared as follows.

A hot-rolled sheet of Fe-36%Ni alloy is cold-rolled to a thickness of 0,
After adjusting the thickness to 3+ nm, recrystallization annealing was performed at 850° C. for 1 minute in an Ar gas atmosphere. Thereafter, finish cold rolling was performed at a rolling rate of 0 to 50%, and the specimen was processed into a tensile test piece. The tensile test piece was subjected to softening annealing at 750°C for 60 minutes and at 830°C for 60 minutes in a mixed gas atmosphere of 90% N2 + 10% H2 (dew point +6°C), and then subjected to a warm tensile test.

From FIG. 2, the 0.2% yield strength of the 830° C. softened annealed material decreases as the finish cold rolling rate increases, and shows a minimum value at a finish cold rolling rate of 5%. Furthermore, when the finishing cold rolling rate is increased, 0.2
% resistance increases. 0, which provides good press formability;
The range of finish cold rolling ratio at which the 2% proof stress is 10 kg/mm2 or less is in the range of 2 to 15%.

On the other hand, the 750°C softened and annealed material shows the same tendency as the 830°C annealed material, in which the 0.2% proof stress temporarily decreases as the finish cold rolling rate increases, and then increases, and the 0.2% proof stress increases by 10 kg. /mm2 or less, the range of finishing cold rolling rate is 5~
It is 20%.

As described above, the 0 and 2% yield strength in the 200°C tensile test of the 750°C softened and annealed material exceeds 10 kg/mm2 when the finish cold rolling ratio is less than 5% or exceeds 20%, which poses a problem during warm pressing. When the finishing cold rolling rate is in the range of 5 to 20%, the 0.2% yield strength is 10 kg/mm2 or less, and 830
A material for a shadow mask which is softened to the same degree as the °C softened annealed material and has good press formability can be obtained.

As mentioned above, at an annealing temperature of less than 800°C, if the finish cold rolling rate before softening annealing is less than 5% or exceeds 20%, the 0.2% proof stress will exceed 10kg/mm2, so the finish cold rolling rate will be It was set at 5 to 20%.

Note that when softening annealing is performed at 700° C. or lower, the recrystallization temperature has not been reached, so no softening occurs, and the temperature is inappropriate for softening annealing.

Hereinafter, specific examples of the present invention will be described.

C: 0.0018%, Si: 0.19%, Mn
: 0.27%, P: 50.002%, S: ≦0.00
05%, Ni: 36.43%, Cr: 50.01%
, Al: 0.005%, N: 0.0018%,
A hot rolled plate consisting of 0: 0.0025%, B: 0.0020% and the remainder Fe was cold rolled to a plate thickness of 0.3 m.
111 cold-rolled sheet, and then heated to 850°C in an Ar gas atmosphere.
Recrystallization annealing was performed for X1 minutes. After that, softening annealing was performed at 700°C, 1730°C, 750°C, 830°C, and 93°C, respectively.
Each treatment was carried out at 0° C. for 60 minutes in a mixed gas atmosphere of 90% N 2 +10% H 2 (dew point +6° C.). A tensile test piece was taken from the sample and tested at 200°C.

Table 1 shows the results of determining the 0.2% yield strength.

Manufacturing method B has a finish cold rolling rate of 15%, which is within the range of the present invention. In manufacturing method B, the softening annealing temperature is 73
The 0.2% yield strength at temperatures above 0°C is below 10 kg/m+n2, and the strength has decreased to a level with good press formability.

On the other hand, manufacturing method A has a finish cold rolling rate of 2%, which is outside the range of the present invention. In manufacturing method A, in order to make the 0.2% proof stress 10 kg/mm2 or less, annealing must be performed at a temperature of 80° C. or higher.

<Effects of the Invention> As described above, according to the present invention, it is possible to manufacture a low-strength shadow mask even at a low softening annealing temperature of less than 800°C before warm pressing, and it is economical and workable. It has excellent effects in terms of efficiency.

[Brief explanation of drawings]

Figure 1 shows a hot-rolled sheet of Fe-36%Ni-Ni-Fe alloy, which was cold-rolled to 92.5% and then recrystallized at 850°C for 1 minute, then finished by varying the rolling ratio. The relationship between the finish cold rolling rate and the grain size number when cold rolling is performed and softening annealing before press forming is performed at 750° C. for 60 minutes or 830° C. for 60 minutes is shown. FIG. 2 shows the results of a warm tensile test conducted at an ambient temperature of 200° C. to determine the 0.2% proof stress.

Claims (1)

[Claims] After cold rolling and subsequent recrystallization annealing using a low thermal expansion alloy mainly composed of Fe and Ni,
A method for producing a material for a shadow mask, which comprises final cold rolling at a rolling rate of 5 to 20%.