JP3235954B2 - Steel plate for shadow mask and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel sheet for a shadow mask in which intermediate annealing is continuously annealed, and a method of manufacturing the same, and more particularly, to a steel sheet for a shadow mask which is excellent in resistance to unevenness in elongation during mask press forming after final annealing. It is intended to provide.

[0002]

2. Description of the Related Art With the enlargement of televisions and the increase in quality and definition of televisions, the required quality of shadow masks incorporated in cathode ray tubes is also increasing. In particular, the problem of color misregistration due to thermal expansion of the shadow mask, and the problem of deflection of the shadow mask due to enlargement, the ratio of shadow masks made of amber alloy is also increasing, but for general-purpose cathode ray tubes, There is still a great demand for decarburized Al-killed steel in terms of manufacturing costs, and in recent years,
There is even a tendency to switch to l-killed steel.

The shadow mask is required to have the following performance in the manufacturing process. There should be no uneven drilling in the mask during etching drilling. The steel sheet is not easily strain-aged during the burning treatment of the resist film and / or the final annealing. Fully recrystallized and softened during final annealing at 600-700 ° C. Non-uniform deformation (uneven stretching) should not occur during press molding. A dense oxide film is formed during the blackening process.

It has been found that the main causes are segregation and non-uniform distribution of inclusions, and countermeasures have been taken based thereon.

[0005] Regarding (1), it is necessary to reduce C in steel to the limit, and the following method has been proposed. (1) The technology that is generally adopted is a technology that significantly reduces C in steel by open coil decarburization annealing after primary cold rolling, and reduces the amount of C to a level that does not substantially cause aging. Japanese Patent Publication No. 54-25492 and Japanese Patent Publication No. 60-30727 correspond thereto. (2) Thoroughly perform degassing during steelmaking to reduce C in steel.
There is a method to reduce the noise, Japanese Patent Publication No. 63-66376,
This is a technique disclosed in JP-A-2-45691. These publications propose a technique for decarburizing C to less than 0.01% by weight (hereinafter, wt%). (3) Further, in order to make the steel sheet non-aging, Ti, N
There is a technology to add carbonitride forming elements such as b and V to precipitate and fix carbon in steel as carbonitride, and it is possible to achieve non-aging even at today's steelmaking decarburization level (20 to 30 ppm). It is. This makes it possible to perform annealing after the primary cold rolling in a continuous annealing line, which is advantageous not only in productivity but also in terms of yield and plate shape. JP-A-57-9857 and JP-A-58-164754 as techniques based on the technical idea.
Has been proposed.

As for the method, there is a method of promoting formation of a dense oxide film in a blackening treatment step using steam oxidation by adding an appropriate amount of Cr.

[0007]

However, none of the methods for satisfying the above-mentioned characteristics are still insufficient.

That is, the method of performing open coil decarburization annealing after primary cold rolling has a disadvantage of a long production time, which is a problem peculiar to batch annealing, and is economically disadvantageous. In addition, surface defects may occur in the coil handling step, and further, there is a problem that a thickness restriction occurs in open coil annealing.

On the other hand, the method of reducing C in steel by degassing at the time of steel making is to reduce the amount of C in steel to substantially 10 ppm or less in order to non-age to a level at which non-uniform deformation does not occur during press forming. It is necessary to reduce it, and this is a level that is difficult to achieve only by degassing during steelmaking. For this reason, it has not yet reached practical use.

In the method of adding a carbonitride forming element, the recrystallization temperature is increased by adding the carbonitride forming element, and the color tone and the density of an oxide film formed during the blackening treatment are deteriorated. Due to the problem described above, this has not yet been put to practical use as a technology that can replace the decarburized Al-killed steel.

The present invention solves these problems and can be manufactured in a short time by making the intermediate annealing after the primary cold rolling a continuous annealing, has no surface defects, and has softening characteristics at the final annealing, An object of the present invention is to provide a steel plate for a shadow mask having excellent stretch resistance during mask press molding after annealing and a method for manufacturing the same.

Specifically, prevention of strain aging caused by residual solid solution carbon, which is a problem when annealed a steelmaking decarburized steel sheet by a continuous annealing method after primary cold rolling, and forming a trace amount of carbonitride in the steel sheet IF (Interstitial Free) with added elements
It is an object of the present invention to reduce the increase in the recrystallization temperature and the deterioration of the blackening property, which are inevitable problems for a steel sheet, to a level that does not cause a practical problem.

[0013]

According to the first aspect of the present invention,
% By weight, C: ≦ 0.002%, Si: ≦ 0.02%,
Mn: 0.05-0.2%, P: ≤0.01%, S:
0.005 to 0.015%, Cr: 0.02 to 0.1
%, Sol. Al: 0.02 to 0.06%, N: ≦ 0.
003%, C + (N / 2): ≦ 30 ppm, O: ≦ 20
ppm, the hot rolled steel strip consisting of the balance Fe and unavoidable impurities is used as a material, and is subjected to primary cold rolling, intermediate continuous annealing, and finish cold rolling. It is a steel plate for shadow masks with excellent unevenness.

According to a second aspect of the present invention, C: ≦% by weight.
0.002%, Si: ≦ 0.02%, Mn: 0.05 to
0.2%, P: ≦ 0.01%, S: 0.005 to 0.0
15%, Cr: 0.02 to 0.1%, sol. Al:
0.02-0.06%, N: ≦ 0.003%, C + (N
/ 2): ≤30 ppm, O: ≤20 ppm and Nb,
One, two or more of V, Zr, and Ti are used in a total amount of 0.
006% or less, from the balance Fe and inevitable impurities
Using a hot-rolled steel strip as a raw material, it is a steel sheet for shadow masks with excellent stretch resistance during mask press forming after final annealing manufactured by performing primary cold rolling, intermediate continuous annealing, and finish cold rolling. is there.

According to a third aspect of the present invention, C: ≦% by weight.
0.002%, Si: ≦ 0.02%, Mn: 0.05 to
0.2%, P: ≦ 0.01%, S: 0.005 to 0.0
15%, Cr: 0.02 to 0.1%, sol. Al:
0.02-0.06%, N: ≦ 0.003%, C + (N
/ 2): ≤30 ppm, O: ≤20 ppm, balance
A method for producing a steel sheet for a shadow mask, comprising subjecting a hot-rolled steel strip made of Fe and unavoidable impurities to a material, and performing primary cold rolling, intermediate continuous annealing, finish cold rolling, and final annealing before mask press forming. is there.

According to a fourth aspect of the present invention, C: ≦% by weight.
0.002%, Si: ≦ 0.02%, Mn: 0.05 to
0.2%, P: ≦ 0.01%, S: 0.005 to 0.0
15%, Cr: 0.02 to 0.1%, sol. Al:
0.02-0.06%, N: ≦ 0.003%, C + (N
/ 2): ≤30 ppm, O: ≤20 ppm and Nb,
One, two or more of V, Zr and Ti in a total amount of 0.0
06% or less, the balance being Fe and inevitable impurities.
A method for producing a steel sheet for a shadow mask, comprising performing primary cold rolling, intermediate continuous annealing, finish cold rolling, and final annealing before mask press forming using a hot-rolled steel strip as a raw material.

The core of the present invention is a series of steps from the final annealing after the finish cold rolling or the stack annealing step (final annealing) of the mask after the etching, in which the residual solid solution C is decarburized after the primary cold rolling. To produce a steel sheet for shadow masks that does not have uneven elongation at the time of forming a mask by continuous annealing after primary cold rolling by reducing the yield point elongation at the non-aging level equivalent to that of steel sheets to 0.2% or less. It is.

A steel sheet in which the sum of 1/2 of C and N in the steel sheet is reduced to 30 ppm or less is used as a basic component, and Ti, Nb,
V, Zr and other carbonitride forming elements with a total amount of 0.006 w
In other words, the steel sheet is contained in the range of t% or less.

The reasons for the limitation will be described below. C: For C, decarburizing annealing after primary cold rolling can be omitted by making an ultra-low carbon steel sheet in advance in the steelmaking stage. In the present invention, C in the steel sheet described later is 30 ppm as a sum of 1/2 of N in the steel sheet.
By specifying as follows, it is possible to reduce the residual solid solution C to a level at which a non-aged steel sheet can be obtained even by the continuous annealing method.

Further, the provision of C and N makes it possible to avoid an increase in the recrystallization temperature during final annealing and to add a small amount of a carbonitride-forming element in a range that does not adversely affect the blackening property. become. Therefore, in the present invention, the upper limit of C in the steel sheet is set to 0.002 wt% that can be decarburized in steelmaking.

N: In the present invention, in order to lower the recrystallization temperature during final annealing, the upper limit of the N content is set to 0.003 wt% for the purpose of minimizing the amount of AlN deposited.

Further, when adding a carbonitride forming element such as Nb, V, Zr, Ti, etc., when the N content is large, a nitride is formed, so that an effective addition which contributes to precipitation fixation of carbon in the steel sheet. Similarly, the upper limit of the N content is set to 0.
003wt%.

FIG. 1 is a diagram showing the effect of the amount of C + (N / 2) on the yield point elongation after final annealing.

C + N: In the present invention, in addition to the limitation of individual components for C and N, C + (N /
2) should be 30ppm or less. Preferably C + (N / 2)
25ppm or less. In other words, in a series of manufacturing processes, up to about 1/2 of the amount of N in the steel sheet cannot be completely precipitated as AlN,
It became clear that it was in a solid solution state, and it was found that it was effective to control C + (N / 2) for the unevenness in the elongation after the final annealing.

Further, it has been found that by reducing C + (N / 2), even when a carbonitride-forming element is added, it is possible to add a trace amount within a range that does not impair the blackening property. Therefore, in the present invention, C + (N / 2) is limited to 30 ppm or less.

Si: Si is an element that deteriorates the denseness and adhesion of the oxide film formed during the blackening treatment. With respect to the performance, there is no practical problem if Si is 0.03 wt% or less, but in the present invention, the content is limited to 0.02 wt% or less so as to satisfy more stringent quality requirements.

Mn: Mn is generally added in an amount of about 10 times or more in accordance with the amount of S in the steel sheet in order to avoid hot embrittlement of the slab by precipitating and fixing S in the steel sheet as MnS. However, excessive Mn deteriorates the uniformity of the oxide film formed during the blackening treatment. Therefore, in the present invention,
As a range to avoid both problems, the addition amount is 0.05 to
Limited to 0.2wt%.

P: Regulation of the amount of P plays an important role in the present invention. FIG. 2 is a diagram showing the effect of the amounts of P and C + (N / 2) on the yield point elongation after the final annealing. As shown in the figure, the P content is 0.01 wt% or less, preferably 0.008 wt%.
By performing the following, the recovery amount of the yield point elongation in the shadow mask that has been subjected to the final annealing is reduced. This indicates that reducing P to 0.01 wt% or less facilitates precipitation of solid solution C in a series of manufacturing steps. Therefore, in the present invention, the content is limited to 0.01 wt% or less in order to avoid unevenness in elongation at the time of mask press molding due to recovery of yield point elongation.

S: S in the steel sheet exists as MnS in the steel sheet. In a steel sheet containing a large amount of S, MnS particles dispersed in the rolling direction induce corrosion unevenness of a hole edge at the time of etching drilling, and are detected as unevenness of transmitted light at the time of precision inspection of a shadow mask. However, when the sulfur content is extremely low to less than 0.005 wt%, the scale releasability during hot rolling is deteriorated, and surface defects due to the biting of the scale occur. Therefore, in the present invention, the content is limited to the range of 0.005 to 0.015 wt% from both viewpoints.

Cr: Cr plays an important role in forming a dense oxide film layer during the blackening treatment of the shadow mask, so the lower limit of the effect of adding Cr is 0.02 wt%.
% Or more. However, when the content is 0.1 wt% or more, not only the effect is saturated, but also there are cases where the blackened coating film becomes uneven, so the addition amount is limited to the range of 0.02 to 0.1 wt%.

O: When C in steel is reduced to the utmost by steelmaking degassing, oxygen blown into molten steel for temperature compensation increases the oxygen level in steel, and alumina formed mainly during the subsequent aluminum deoxidation treatment Due to the inclusions, slab internal defects are likely to occur.

Such alumina-based inclusions are likely to be distributed in the form of dots in the rolling direction of the steel sheet as B-based inclusions.
It is easy to induce white stripe unevenness defects. Therefore, in the present invention, the total oxygen content in the steel sheet is specified to be 20 ppm or less.

Sol.Al: Al is added to molten steel as a deoxidizing agent to increase the cleanliness of the steel. In addition, the solid solution Al in the steel sheet converts N in the steel sheet into AlN in the hot rolling stage. Precipitation fixing serves to avoid nitrogen aging. In the present invention, the amount of sol. Al is limited to 0.02 to 0.06 wt% as an effective range for precipitating and fixing N in the steel sheet.

In the present invention, by adding the following trace elements in addition to the above basic components, aging can be further improved without impairing the basic performance required for the shadow mask.

Nb, V, Zr, Ti: These carbonitride forming elements not only increase the recrystallization temperature during final annealing, but also have an adverse effect on the formation of an oxide film during blackening.
In the present invention, in order to solve these problems, Cr
Amount, total amount of carbonitride forming element and C + (N / 2) in steel sheet
It was found that the problem could be solved by limiting the amount at the same time.

FIG. 3 is a diagram showing the influence of Σ (Nb, V, Zr, Ti) and C + (N / 2) on the yield point elongation after final annealing.

Σ (Nb, V, Zr, Ti) ≦ 0.006 wt%
In addition, under the condition of C + (N / 2) ≦ 30 ppm, it is possible to reduce the defective rate of unevenness in elongation while maintaining excellent properties of the blackened coating film in a favorable state.

From the above results, according to the present invention, Nb, V,
For each element of Zr and Ti, the total amount of one or more elements is limited to a range of 0.006 wt% or less.

Preferably, the content of C + (N / 2) is 25 ppm or less, and the total amount of one or more of the elements Nb, V, Zr, and Ti is 0.004 wt% or less.

The primary cold rolling may be performed by a conventional method, and the intermediate continuous annealing is a recrystallization annealing and does not need to be a special annealing. Decarburization and denitrification may be carried out by adjusting the atmosphere, but basically, the production time peculiar to batch annealing is long, surface defects occur in the coil handling process, and plate thickness restrictions in open coil annealing etc. This eliminates the problematic disadvantages of conventional annealing.

The finish cold rolling is performed in order to obtain a predetermined plate thickness, to secure softening characteristics at the time of final annealing in the final annealing, and to provide resistance to uneven stretching at the time of mask press molding after the final annealing.
Usually, rolling is performed at a rolling rate of about 45 to 85%.

The final annealing of the present invention may be performed before or after the perforation by the photoetching process. In the former case, the final annealing may be performed subsequent to the burning process of the resist film, or when the blackening process is performed before pressing, it may be performed during the blackening process.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION

 (Example 1)

[0044]

[Table 1]

After smelting the steel, it was made into a slab by continuous casting under light pressure. After the slab was heated to 1200 ° C., a hot-rolled steel sheet having a finishing temperature of 890 ° C. and a winding temperature of 620 ° C. and a thickness of 1.8 mm was obtained.

In order to reduce semi-macro and macro-segregation of P and S in the steel sheet, slab light casting is performed during continuous casting, and slab high temperature heating of 1150 ° C. or more is performed from the viewpoint of uniform miniaturization of MnS. Is preferred.

The chemical compositions of the obtained steel plate numbers 1 to 22 are as follows:
As shown in Table 1. Components not shown are Fe and unavoidable impurities.

After pickling this hot-rolled steel sheet, it was subjected to primary cold rolling to a sheet thickness of 0.65 mm, and then to recrystallization intermediate annealing at 650 ° C. in a continuous annealing line. Subsequently, the annealed plate was
After finishing cold rolling to m, the mask surface was perforated by photoetching, final annealing was performed, mask press forming was performed, and finally blackening treatment was performed.

The atmosphere of the final annealing is 15% H ₂ +8
5% N ₂ , dew point 18 ° C, temperature 700 ° C, retention time 10
Minutes. The properties of the resulting blackened coating film and the yield point elongation which induces uneven stretching when press molded into a shadow mask were determined.

The properties of the blackened coating film were evaluated by visual inspection. ◎: No peeling, no unevenness, ム ラ unevenness, × x peeling.

Table 1 shows the results. The steel sheet in the component range of the present invention has only the blackening property of 皮膜, and the yield point elongation after the final annealing is 0.2% or less, and both have excellent properties.

(Example 2)

[0053]

[Table 2]

After smelting the steel, it was made into a slab by continuous casting under light pressure. After the slab was heated to 1200 ° C, a hot-rolled steel sheet having a finishing temperature of 900 ° C, a winding temperature of 620 ° C and a thickness of 1.8 mm was obtained.

Light slab casting at the time of continuous casting is carried out for the purpose of reducing semi-macro and macro segregation of P and S in the steel sheet, and slab high temperature heating of 1150 ° C. or more is carried out from the viewpoint of uniform miniaturization of MnS. did.

Table 2 shows the chemical compositions of the obtained steel sheets Nos. 1, 6, 20, and 23 to 35. Components not shown are Fe and unavoidable impurities.

After pickling this hot-rolled steel sheet, it was subjected to primary cold rolling to a sheet thickness of 0.60 mm, followed by intermediate recrystallization annealing at 700 ° C. in a continuous annealing line. Subsequently, the annealed plate was
After finishing cold rolling to m, the mask surface was perforated by photoetching, final annealing for blackening treatment and softening annealing was performed, and mask press forming was performed.

The atmosphere of the final annealing is 15% H ₂ +8
5% N ₂ , dew point 18 ° C, temperature 700 ° C, retention time 10
Minutes. The properties of the resulting blackened coating film and the yield point elongation which induces uneven stretching when press molded into a shadow mask were determined.

The evaluation of the properties of the blackened coating film was visually observed. ◎: No peeling, no unevenness, ム ラ unevenness, and x: peeling.

Table 2 shows the results. The steel sheet in the component range of the present invention has only the blackening property of 皮膜, and the yield point elongation after the final annealing is 0.2% or less, and both have excellent properties.

[0061]

According to the present invention, a steelmaking decarburized steel sheet is subjected to continuous annealing after primary cold rolling, and has excellent softening properties at the time of final annealing, and excellent resistance to uneven stretching at the time of mask press molding after final annealing. A steel sheet for use and a method for producing the same were obtained.

Further, a trace amount of a carbonitride forming element was added.
The rise of recrystallization temperature and deterioration of blackening properties, which are inevitable problems for IF (Interstitial Free) steel sheets, have been reduced to levels that do not pose a practical problem.

[Brief description of the drawings]

Figure 1: C + (N / 2) on yield point elongation after final annealing
FIG. 4 is a diagram showing the influence of the amount.

FIG. 2: P and C + on yield point elongation after final annealing
It is a figure which shows the influence of (N / 2) quantity.

FIG. 3 shows the effect of yield point elongation after final annealing on ｂ (Nb,
FIG. 4 is a diagram showing the influence of V, Zr, Ti) and C + (N / 2).

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yasuhiro Matsuki 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. Examiner Kenichi Morooka (56) References JP-A-6-330167 (JP, A) JP-A-5-214490 (JP, A) JP-A-2-254139 (JP, A) JP-A-58-81926 (JP, A) JP-A-60-152634 (JP, A) JP-A-5-31330 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 38/00-38/60 C21D 9/46-9/48

Claims (4)

(57) [Claims] 1. The method according to claim 1, wherein C: ≦ 0.002%, Si:
≦ 0.02%, Mn: 0.05-0.2%, P: ≦ 0.
01%, S: 0.005 to 0.015%, Cr: 0.0
2 to 0.1%, sol. Al: 0.02 to 0.06%,
N: ≦ 0.003%, C + (N / 2): ≦ 30 ppm,
O: contains ≦ 20 ppm, balance Fe and unavoidable impurities
As a material for hot rolled strip made of, primary cold rolling, intermediate continuous annealing, steel sheet excellent for a shadow mask stretch resistant beauty unevenness of when the mask is press-formed after final annealing which is produced by performing the finish cold rolling . 2. In% by weight, C: ≦ 0.002%, Si:
≦ 0.02%, Mn: 0.05-0.2%, P: ≦ 0.
01%, S: 0.005 to 0.015%, Cr: 0.0
2 to 0.1%, sol. Al: 0.02 to 0.06%,
N: ≦ 0.003%, C + (N / 2): ≦ 30 ppm,
O: ≦ 20 ppm and Nb, V, Zr, one or more of Ti, include 0.006% or less in total, the remaining
Using hot-rolled steel strip consisting of part Fe and unavoidable impurities, it is excellent in unevenness resistance to elongation during mask press molding after final annealing manufactured by performing primary cold rolling, intermediate continuous annealing, and finish cold rolling. Steel plate for shadow mask. 3. C .: 0.002% by weight, Si:
≦ 0.02%, Mn: 0.05-0.2%, P: ≦ 0.
01%, S: 0.005 to 0.015%, Cr: 0.0
2 to 0.1%, sol. Al: 0.02 to 0.06%,
N: ≦ 0.003%, C + (N / 2): ≦ 30 ppm,
O: contains ≦ 20 ppm, balance Fe and unavoidable impurities
A method for producing a steel sheet for a shadow mask, comprising subjecting a hot-rolled steel strip made from a material to primary cold rolling, intermediate continuous annealing, finish cold rolling, and final annealing before mask press forming. 4. In% by weight, C: ≦ 0.002%, Si:
≦ 0.02%, Mn: 0.05-0.2%, P: ≦ 0.
01%, S: 0.005 to 0.015%, Cr: 0.0
2 to 0.1%, sol. Al: 0.02 to 0.06%,
N: ≦ 0.003%, C + (N / 2): ≦ 30 ppm,
O: ≦ 20 ppm and containing one or more of Nb, V, Zr, and Ti in a total amount of 0.006% or less, and the balance
A method for producing a steel sheet for a shadow mask, comprising: performing a primary cold rolling, an intermediate continuous annealing, a finish cold rolling, and a final annealing before mask press forming, using a hot-rolled steel strip made of Fe and unavoidable impurities as a raw material.