JPH03140440A - Stock for shadow mask excellent in etching property and workability - Google Patents

Abstract

PURPOSE:To obtain the stock for a shadow mask excellent in etching properties and workability in pressing by forming it from the compsn. contg. each prescribed amt. of C, Mn, S, sol. Al, N, Sb and the balance substantial Fe. CONSTITUTION:The stock for a shadow mask is formed from a steel contg., by weight, <=0.002% C, 0.1 to 0.4% Mn, <=0.010% S, 0.01 to 0.05% sol. Al, <=0.008% N, 0.002 to 0.010% Sb and the balance Fe with inevitable impurities. The steel as the stock is made into a cold rolled sheet by an ordinary method. The cold rolling is executed preferably at >=20% draft for sufficiently producing recrystallization even at a low temp. of about 600 deg.C in an annealing stage after the above stock for a shadow mask is subjected to photoetching and is cut into a flat mask. By using the above stock, a shadow mask for a large- size high definition television can easily be manufactured at high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION First, the reason for limiting the content of the components contained in the steel that is the material for the shadow mask of the present invention will be described.

C: C is a component that greatly affects the recrystallization temperature during annealing, and if the content is large, it causes non-uniform deformation (stretcher strain) that occurs during press forming after annealing. Therefore, recrystallization occurs even at low temperatures of around 600°C,
Furthermore, in order to prevent stretcher strain from occurring during press molding, the C content needs to be 0.002 wt% or less.

Mn: Mn is an element necessary to avoid hot embrittlement, and in order to obtain this effect, it is necessary to add 0.1 wt% or more. However, addition of a large amount causes an increase in the recrystallization temperature and an increase in A-based inclusions that cause uneven etching, so the upper limit is set to 0.4 wt%.

S: S combines with Mn to form MnS, causing uneven etching and deteriorating press formability, so the content is preferably small, and from this point of view, the upper limit of the content is set to 0. .010 wt% or less.

Sol, AIt is a component for fixing solid solution N, which causes stretcher strain, as Alx during nibless molding, and from this point of view, it is necessary to add 0.01 wt% or more. However, excessive addition causes an increase in the recrystallization temperature and an increase in inclusions, so the upper limit is set at 0.05.
Let it be wt%.

Like C, NUN causes stretcher strain, so it is desirable that its content be small. The above sol. o, ooaw can be completely fixed by Al
The upper limit is t%.

Sb: Sb is an essential element in order to obtain excellent etching characteristics and press formability, which are the objectives of the present invention.
With regard to etching properties, it provides very uniform etching properties compared to those without sb additives. Although the mechanism is not clear, it is presumed that sb lowers the energy of areas that tend to cause uneven etching, such as grain boundaries and inclusions, and brings about the same etching performance as the matrix in such areas. . Regarding press formability,
sb suppresses the excessive growth of crystal grains accompanying an increase in annealing temperature, which tends to occur in regions with a low C content, and provides stable press formability against fluctuations in annealing temperature.

Therefore, when sb is added, stable press formability can be obtained even if the annealing temperature varies from a low temperature of about 600°C to a high temperature of about 900°C.

The effect of these sb is that its content is 0.002 wt%
As it becomes clear from the above, the lower limit value is 0.002wt
%. In addition, excessive addition causes an increase in recrystallization temperature and a prolonged etching time, so to prevent such drawbacks, the upper limit of the content is set to 0.010 wt.
%.

Next, a method for producing steel, which is a material for a shadow mask, having the above composition will be described.

Steel having the above composition is made into a cold rolled plate by a normal method.

The amount of C may be adjusted by using a method such as degassing equipment during steel manufacturing to lower it, and the amount of C may be adjusted by using a method of lowering it by using degassing equipment etc. at the time of steel manufacturing.
The steel may be hot rolled, pickled, cold rolled, and then decarburized by an open annealing method.

The amount of S is generally adjusted by methods such as hot metal desulfurization, but if necessary, flux injection (f
lux 1nJection).

Further, the amount of N is adjusted by adjusting the blowing gas amount, time, etc. during molten steel smelting.

The cold rolling is carried out at a temperature of 20° C. in order to sufficiently cause recrystallization even at a low temperature of about 600° C. in the annealing process after the shadow mask material of the present invention is photo-etched and cut into flat masks. It is desirable to perform cold rolling at a reduction rate of % or more.

<Example> Hereinafter, the present invention will be explained in detail by way of examples.

(Example 1) 0.001 wt%C-0.3wt%Mn-
0,008wt%S-0,03wt%sol,A
11-0.005 wt%N is the basic component, Sb is 0
．． 005 wt% added steel and non-added steel were heated in a converter,
It was melted in the degassing process and made into a slab by continuous casting. 2.8m slab by hot strip mill
The coil was formed into a hot rolled coil having a thickness of m, pickled, and then cold rolled to a thickness of 0.8 mm using a cold strip mill. Next, recrystallization annealing is performed by continuous annealing, and then 0.25 m
It was cold rolled to a thickness of m. This cold-rolled plate was photo-etched and perforated, and 500
After annealing at a specific temperature within the range of ~900°C (held for about 10 minutes), a tensile test piece was cut out from the edge of the plate and subjected to a tensile test, and the yield stress and yield elongation were measured and calculated (
The method is based on JIS-22241).

In addition, the perforated and annealed plate was pressed into a mask shape, and the appearance was inspected.

Figures 1 and 2 show the relationship between annealing temperature and yield elongation and yield stress, which have the greatest relationship to press formability.

The sb-added steel, which is the steel of the present invention, properly completes recrystallization even when the annealing temperature is as low as 600° C., and has zero yield elongation.

Moreover, the variation in yield stress is extremely small in the temperature range exceeding 800° C. and up to 900° C., which is the temperature range in which shadow masks are normally annealed. On the other hand, in the comparative steel, sb-free steel, recrystallization is not completed at an annealing temperature of 600°C.
Yield elongation remains, and the yield stress changes greatly with changes in annealing temperature. In addition, in the appearance inspection after processing into a mask shape, the sb-free steel was annealed at 600°C and some stretcher strain occurred, and dimensional errors occurred due to changes in the annealing temperature, whereas the steel of the present invention ,
No stretcher strain was observed and no visible dimensional errors occurred for all steels annealed within the temperature range of 600-900°C.

(Example 2) 0.05 wt%C-0,2wt%Mn-0,00
5wt%S-O, 04wt%sol, All-0,
006wt%N is the basic component, sb is 0.006 +
Steel with vt% addition and steel without addition were melted in a converter and made into slabs by continuous casting. The slab was hot rolled into a 2.6 mm thick coil in a hot strip mill, pickled and then cold rolled in a cold strip mill to a thickness of 0.7 mm. This coil was annealed in an oven, and the C content was 0.
It was decarburized to 0.008 wt % and then cold rolled to a thickness of 0.2 mm.

This cold-rolled plate is photo-etched and perforated,
We conducted an inspection and calculated the defective rate. The photo-etching was performed so that holes were formed according to the standards for shadow masks for 29-inch color televisions, and the number of sheets to be inspected was as follows:
Approximately 10,000 steel plates were used for each steel plate. Then, through inspection, masks with at least one irregular hole were counted as defective masks. Incidentally, an irregular hole is one in which the edge of the hole is chipped due to an inclusion or the like, or one in which the hole does not open due to undissolved material.

As a result, the defect rate of the comparison steel, sb-free steel, was 2.5.
%, whereas the defect rate of the sb-added steel, which is the steel of the present invention, was 0.3%, making it clear that the steel of the present invention exhibits good etching properties.

(Example 3) A cold-rolled steel plate having a thickness of 0.15 to 0.30 mm was manufactured with the composition shown in Table 1. As shown in Table 1, the amount of C was adjusted by either a method of performing degassing treatment during melting in a converter or a method of decarburizing during open annealing. All ingots were made by continuous casting. The thickness of the hot rolled plate is 2.
It was 0 to 3.2 mm. Hot rolled plate 0.5~1.0m
After cold rolling to a thickness of m, recrystallization annealing was performed by continuous annealing, tight annealing, or oven annealing, and then cold rolling to the above-mentioned predetermined thickness.

This cold-rolled plate is photo-etched and perforated,
We conducted an inspection and calculated the defective rate. The photo-etching was carried out to form holes according to the standards for shadow masks for 19-29 inch color televisions, and the number of sheets tested was about 10,000 for each steel plate. and,
As in Example 2, masks in which at least one irregular hole was present during inspection were counted as defective masks.

Those that were successfully photo-etched were annealed and pressed, and their press formability was evaluated.
Note that the annealing temperature was a predetermined temperature within the range of 600 to 900°C.

Table 2 shows the defect rate during photoetching and the evaluation results of press formability. As is clear from these results, the steel of the present invention exhibits superior etching properties and formability compared to the comparative steel.

Table ◆SS is an abbreviation for stretcher strain. Underlined lines indicate those outside the scope of the present invention.

<Effects of the Invention> According to the present invention, a shadow mask material having excellent etching characteristics and pressing characteristics is provided.

Therefore, a shadow mask for a cathode ray tube for a large, high-quality television can be manufactured easily and with high yield.

FIG. 1. Brief Description of the Drawings FIG. 1 is a graph showing the relationship between yield elongation and annealing temperature.

FIG. 2 is a graph showing the relationship between yield stress and annealing temperature.

FIG.2 f, A (1.

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Liu Ji Todoroki C)

Claims (1)

[Claims] (1) C: 0.002wt% or less, Mn: 0.1-0.
4wt%, S: 0.010wt% or less, sol. Al:
Etching properties and processability characterized by containing 0.01 to 0.05 wt%, N: 0.008 wt% or less, Sb: 0.002 to 0.010 wt%, and the remainder consisting of iron and inevitable impurities. Excellent shadow mask material.