JP3457794B2 - Manufacturing method of shadow mask material - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method for manufacturing a thin steel sheet used for a color selection electrode such as a shadow mask mounted in a cathode ray tube of a color TV. 2. Description of the Related Art A shadow mask is produced by cold rolling or primary cold rolling-intermediate annealing-secondary cold rolling following hot rolling in a material maker, etching-annealing by a user (hereinafter referred to as "user annealing"). It is manufactured through the following steps:-leveling-press molding-blackening. For the quality of a shadow mask, etching properties, press moldability, blackening properties, etc. are required. In particular, uniform deformability during press molding is important. Of the TV screen or the gap between the holes, resulting in a noticeable adverse effect on the quality of the TV screen, such as a color shift. For this reason, there is a need for a shadow mask material that does not generate or does not generate the yield point elongation that causes non-uniform deformation. [0004] One of the causes of the yield point elongation is solid solution C remaining after user annealing.
C processing, JP-B-60-30727 and JP-B-63-408
The method of performing strong decarburization annealing at the steel plate stage as disclosed in, for example, Japanese Patent Publication No. 48, can reduce the yield point elongation to a level that hardly occurs. On the other hand, another cause of elongation at the yield point is solid solution N absorbed from the atmosphere during user annealing. It has been clarified that this absorption N phenomenon tends to occur when the amount of S in the steel is small, or when user annealing is performed at high temperature annealing or when the atmosphere has a low dew point. It is not clear at present whether these factors affect the dissociation of N molecules at the surface of the steel sheet, or the diffusion into the steel after dissociation, or both. If the amount of S in the steel is increased to prevent N absorption, the segregation of MnS becomes remarkable and streak-like unevenness tends to occur during etching.
A method of manufacturing a shadow mask in which the amount of S is set to 0.01% or less, the user annealing is set to 750 ° C. or less and / or the dew point is set to 0 ° C. or more is disclosed. [0007] However, in recent years,
Due to the development of electromagnetic stirring technology during casting in steelmaking, the upper limit of the amount of S that does not cause etching failure due to segregation of MnS has been widened to 0.02%, as in the method described in JP-A-63-286524. Specifying the amount of S as 0.01% or less is
It is not preferable because the cost of the billet increases or the operation becomes difficult. Furthermore, the conditions of the user annealing are not necessarily economically favorable conditions for the user.
The amount cannot be reduced to zero, and the occurrence of elongation at yield cannot be completely suppressed. The present invention has been made in order to solve such a problem, and does not perform a special de-sintering treatment and stably increases the yield point elongation due to N absorption without depending on the conditions of user annealing. It is an object of the present invention to provide a method of manufacturing a shadow mask material capable of suppressing the occurrence. Means for Solving the Problems The above object is described in terms of% by weight,
C: 0.0010 to 0.0025%, Si: ≤ 0.1%, Mn: 0.1 to 0.3%, P: ≤ 0.
015%, S: ≤ 0.02%, sol.Al: 0.01-0.08%, N: ≤ 0.007%, C
r: steel containing 0.02-0.10%, after hot rolling, 600-750 ° C
Rolled and pickled , 750 to 880 in an atmosphere with a dew point of -20 ° C or less
The problem is solved by a method for producing a shadow mask material, wherein annealing is performed at a temperature of not less than 30 seconds and not more than 10 minutes, and the product thickness is obtained by cold rolling. The reasons for each limitation will be described below. Incidentally, the present inventors have investigated the relationship between the non-uniform deformation and the yield point elongation in advance, it has been found that if the yield point elongation is 0.6% or less, non-uniform deformation does not occur, the following yield point For limiting reasons relating to elongation, 0.6% was used as the evaluation criterion. [0011] C: more than 0.0025%, the not completely precipitated as Fe ₃ C, since precipitation driving force of Fe ₃ C is decreased as less than 0.0010% causes an increase of solute C, and the yield point elongation of more than 0.6% appear. For this reason, it is specified as 0.0010 to 0.0025%. Si: If it exceeds 0.1%, the steel sheet hardens, which is not preferable. If Mn: more than 0.3%, the steel sheet is hardened, which is not preferable. If it is less than 0.1%, the scale peeling property in pickling after hot rolling is deteriorated. For this reason, it is defined as 0.1 to 0.3%. [0014] If P: more than 0.015%, the steel sheet is not only hardened, but also has an adverse effect on the etching characteristics because it is an element that is easily segregated. For this reason, it is defined as ≦ 0.015%. S: If it exceeds 0.02%, inclusions increase and adversely affect the etching characteristics. Sol.Al:Al is not only necessary for deoxidizing steel, but also has a role of fixing nitrogen in steel as nitride.
If it is less than 0.01%, the nitride does not precipitate sufficiently, and
If the content exceeds 08%, the nitride becomes coarse and adversely affects the etching characteristics. Therefore, the content is specified in the range of 0.01 to 0.08%. N: If N exceeds 0.007%, nitrides increase and adversely affect the etching characteristics. Cr: The most important component for the present invention. The present inventors have used ultra-low carbon steel to which Cr has been added,
By optimizing the hot rolling coiling temperature and intermediate annealing conditions to form an appropriate Cr-enriched layer on the steel sheet surface, N
It has been found that the penetration of atoms into steel can be prevented. 0.02
If it is less than 0.10%, this effect cannot be obtained, and if it exceeds 0.10%, the surface layer becomes extremely thick and the absorption N resistance deteriorates.
Specify to 0.10%. The mechanism of the suppression of N absorption due to the concentration of Cr on the surface layer is considered as follows. That is, since Cr is a nitride-forming element and has a strong affinity for N 2, if Cr is present at a stoichiometric concentration higher than that at which nitride is formed, it rather promotes the penetration of N 2. However, less than this suitable Cr
In the concentration region, the diffusion of N is slowed down because Cr and N do not reach the formation of nitrides and maintain their interaction, and
The performance is improved. In order to form an appropriate Cr-enriched layer on the surface of the steel sheet so that N atoms can be prevented from entering the steel, the hot-rolled steel strip may be wound at 600 to 750 ° C. after hot rolling. . If the temperature is lower than 600 ° C, the surface concentration of Cr becomes insufficient.
Of the surface layer becomes remarkable, and conversely, the absorption N 2 resistance deteriorates. Since the surface layer concentration of Cr progresses along with the oxidation of Fe, not only the winding conditions after hot rolling but also the hot rolling slab heating conditions are considered important. The temperature is as high as 1100 to 1250 ° C, and the Cr concentration is concentrated on the base iron-scale interface and is removed together with the concentrated layer in the descaling until the finish rolling, so that there is almost no effect. On the other hand, at the winding stage after hot rolling,
Since the temperature is low and oxygen enters through the scale, the oxygen partial pressure is low, the oxidation of the base iron becomes slow, and the concentration of Cr on the surface layer becomes moderate. The Cr-concentrated layer formed on the surface layer of the hot-rolled sheet by controlling the winding temperature in this manner is further compressed by cold rolling after pickling or subjected to intermediate annealing to further increase the Cr concentration. Increased uniformly. The effect of the present invention is further enhanced if the intermediate annealing is carried out at 750 to 880 ° C. for 30 seconds or more and 10 minutes or less in an atmosphere having a dew point of −20 ° C. or less. In particular, a dew point of -20
When the temperature is lower than or equal to ° C., the formation of an oxide film on the surface of the steel sheet during the intermediate annealing is suppressed, so that the penetration of N 2 during the user annealing can be more effectively prevented. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Other elements are not particularly specified. However, even if they contain 70 ppm or less of Sn, Sb, 0.1% or less of Cu, or 0.01% or less of V, Zr, etc. The effect of the invention is not impaired. The molten steel adjusted to the component system within the scope of the present invention is formed into a slab by ingot-bulking rolling, continuous casting, thin slab casting, etc., and then hot-rolled directly or through a heating furnace. You. The atmosphere in the intermediate annealing may be a non-oxidizing atmosphere such as H ₂ + N ₂ mixed gas. Next, the effects of the present invention will be described with reference to examples. First, steels A to O of the present invention and comparative steels a to i shown in Table 1 were smelted in a converter and then continuously cast and hot-rolled into steel strips having a thickness of 2.8 mm. Subsequently, after pickling, a portion was cold-rolled to a thickness of 0.22 mm without intermediate annealing, and a portion was cold-rolled to a thickness of 0.65 mm, and then subjected to a continuous annealing furnace in Tables 2 and 3. Intermediate annealing was performed at the dew point, temperature, and time shown in FIG. 3, and cold rolling was again performed to finish the sheet thickness of 0.22 mm, thereby producing a shadow mask material. The atmosphere of the continuous annealing furnace is
1 is a N ₂ atmosphere containing to 20% H _2. Some of these shadow mask materials are etched, and some are left unetched.
User annealing was simulated under a condition of easy absorption of N at ℃ x 20 minutes and dew point -30 ℃, and leveling was applied. [0030] The etched product was further subjected to a blackening treatment and then press-molded into a cathode ray tube shape, and the mask formability was evaluated. Here, the mask formability indicates the degree of influence on the screen quality due to the deviation of the shape and interval of the etching holes, and irradiates the mask with a light beam to visually evaluate whether or not there is uneven transmission of the light beam. ○: good when there was no unevenness; x: poor when there was unevenness and poor. With respect to the unetched one, a JIS No. 5 test piece was cut out and subjected to a tensile test to measure the yield point elongation. The test results are shown in Tables 2 and 3. No.2, No.4
For example, the components, the coiling temperature after hot rolling, and those in which the intermediate annealing conditions are within the scope of the present invention, the yield point elongation is 0.6% or less,
It can be seen that the mask formability is also good. On the other hand, even if the components are within the range of the present invention, such as No. 1 or No. 8, if the hot-rolling winding temperature is not appropriate, the yield point elongation exceeds 0.6%, and the mask moldability increases. Is inferior. In addition, when the components are out of the range of the present invention, such as No. 39 and No. 40, the yield point elongation is large and the mask formability is inferior, even if the hot-rolling winding temperature is within the range of the present invention. . FIG. 1 shows the relationship between the hot-rolling winding temperature and the yield point elongation. It can be seen that a yield point elongation of 0.6% or less can be obtained by setting the hot rolling coiling temperature at 600 to 750 ° C. In particular, in the sample subjected to the intermediate annealing, a lower yield point elongation is obtained. [Table 1] [Table 2] [Table 3] Since the present invention is configured as described above, the yield point due to the absorption of N can be stably performed without performing any special de-S treatment and without depending on the conditions of the user annealing. A method for producing a shadow mask material that can suppress the occurrence of elongation can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a relationship between a hot-rolling winding temperature and a yield point elongation.

Continuation of the front page (72) Inventor Yasuhiro Matsuki 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Yoshihiro Hosoya 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Junji Okamoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (56) References Table 9-503825 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C21D 9/46 C21D 8/02 C22C 38/00 301 C22C 38/18 H01J 29/07

Claims (1)

(57) [Claims] [Claim 1] C: 0.0010 to 0.0025%, Si: ≦ 0.1% by weight
%, Mn: 0.1-0.3%, P: ≤ 0.015%, S: ≤ 0.02%, sol.Al: 0.0
Steel containing 1 to 0.08%, N: ≤ 0.007%, Cr: 0.02 to 0.10% is rolled and pickled at 600 to 750 ° C after hot rolling, and has a dew point of -20 ° C or less.
Hold at 750-880 ° C for 30 seconds or more and 10 minutes or less in the atmosphere below
A method for producing a shadow mask material, comprising annealing and cold rolling to a product thickness.