JP3294892B2 - Sealing alloy material and heat treatment method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing alloy such as a support stud for supporting a shadow mask of a cathode ray tube and a heat treatment method thereof.

[0002]

2. Description of the Related Art As alloys used for sealing with glass, ceramics, etc., there are Fe-42Ni-6Cr alloy, F
e-42 to 50Ni alloy, Fe-29Ni-17Co alloy, Fe-18Cr alloy and the like are used. Among them, an Fe-18Cr alloy is widely used as a shadow mask support component such as a support stud because it has a thermal expansion coefficient close to that of glass used for a cathode ray tube. For the support stud, a bar-shaped material that has been cold forged and cut and processed into a cup having the cross-sectional shape shown in FIG. 1 has been used. However, this support stud 10
Has the disadvantage that it requires a large number of processing steps and is heavy.

Recently, with the development of press working technology, the number of working steps can be reduced, and a support stud 20 having a sectional shape shown in FIG. Has begun to be used in the department. The thin steel sheet used for the support stud 20 is generally subjected to smelting, hot rolling, annealing and cold rolling.
Finish annealing for heating at 1050 ° C. for 0.5 to 5 minutes is performed. After processing a thin steel plate into a cup shape by pressing, the heating temperature is 1100 to 1200 ° C and the heating time is 10 to 10.
A preliminary oxidation treatment is performed in a wet hydrogen gas atmosphere for 60 minutes. By the preliminary oxidation treatment, an oxide film effective for sealing the glass is formed on the surface.

[0004]

As a characteristic required for the support stud, it is required that the support stud has sufficient strength to support a relatively heavy shadow mask.
In this regard, the support stud 10 (FIG. 1) manufactured from a bar-shaped material by cold forging and cutting has a large thickness and high strength reliability. On the other hand, the support stud 20 (FIG. 2) manufactured by pressing a thin steel plate is thin. When the support stud 20 is exposed to a high temperature at the time of preliminary oxidation, recrystallization in the curved portion 21 that has undergone large processing proceeds preferentially in comparison with the flat portion 22. As a result, the crystal grains of the curved portion 21 are coarsened, and there may be a difference in strength between the curved portion 21 and the flat portion 22 where the coarsening of the crystal grains does not proceed so much, and the curved portion 21 is likely to be deformed, cracked, or the like. Become.

[0005] When the crystal grains become coarse and penetrate the plate thickness, the front and back of the plate thickness are connected by a single crystal grain boundary, so that a slow leak due to the diffusion of the gas boundary is likely to occur. as a result,
The airtightness of the support stud is reduced, and the performance of the CRT is significantly impaired. In this regard, in order to secure necessary airtightness, it is required that crystal grains after pre-oxidation are three or more fine grains stably with respect to the plate thickness. However, in the conventional manufacturing method, it was difficult to stably obtain a fine grain structure in a pre-oxidized state. Further, the problems of strength, airtightness, etc. are not limited to the support studs, but also apply to other sealing parts such as a lead frame for a fluorescent display tube manufactured from a thin steel plate.

The present invention has been devised to solve such a problem, and performs a two-stage finish annealing on an Fe-18Cr alloy in which the contents of Ti, C, N and S are specified. Thereby, a grain-sized structure having a uniform crystal grain size after finish annealing is obtained, and excellent reliability is satisfied to satisfy that the crystal grains after pre-oxidation are three or more fine grains stably with respect to the plate thickness. An object of the present invention is to provide a sealing alloy material.

[0007]

In order to achieve the object, the alloy material for sealing of the present invention has a C content of 0.005 to 0.0.
8% by weight, Si: 0.05 to 1.0% by weight, Mn: 0.
10 to 0.80% by weight, S: 0.005 to 0.015% by weight, Cr: 16 to 25% by weight, N: 0.005 to 0.5%.
02% by weight, Ti: 0.15 to 0.60% by weight, Al:
A Fe alloy containing 0.01 to 0.30% by weight, wherein the crystal grains after the finish annealing are sized to have a grain size of 5 to 6. This sealing alloy material holds the Fe alloy having the above-described composition at 800 to 950 ° C. for 30 minutes or less, cools it to 500 ° C. or less, and further cools it to 900 to 1050 ° C.
It is manufactured by performing a two-stage finish annealing that is held at 30 ° C. within 30 minutes.

[0008]

[Action] In order for a sealing alloy such as a support stud manufactured by press working to have sufficient shadow mask support strength and to maintain excellent airtightness, it is necessary to suppress the growth of crystal grains during the preliminary oxidation treatment. Assuming that there is,
The present inventors have investigated and studied the change of crystal grains after the preliminary oxidation from various viewpoints. As a method for suppressing the coarsening of crystal grains, it is conceivable to lower the heating temperature of the preliminary oxidation treatment or shorten the heating time. However, the preliminary oxidation treatment at a low temperature or for a short time forms a thin oxide film, which has a disadvantage of lowering the sealing strength. Further, by containing Ti having a high affinity for C and N in the alloy,
It is also known to prevent coarsening by forming a carbonitride of Ti (see “Stainless Steel Handbook”, pages 360-361, published by Nikkan Kogyo Shimbun, December 25, 1980).

The present inventors also investigated the effect of the addition of Ti. As for the suppression of coarsening of the support stud by press working, the crystal grains after the pre-oxidation were stably three or more fine with respect to the plate thickness. It was confirmed that the requirements for the grains were not satisfied, and it was not sufficient to only precipitate the carbonitride of Ti. The coarsening of the crystal grains is greatly affected by the composition design of the alloy and the structure after the finish annealing. The present inventors have experimentally confirmed that sizing the crystal grains after the finish annealing effectively prevents the coarsening of the crystal grains after the preliminary oxidation treatment. From the experimental results, the first stage of the Fe-Cr-based alloy, in which the content of S in addition to Ti, C, and N is specified, is 800
It has been found that when performing two-stage finish annealing in which the second stage is heated to 900 to 950 ° C and the second stage to 900 to 1050 ° C, the coarsening of the crystal grains after the preliminary oxidation is effectively suppressed. In addition, the one-stage and two-stage heating, after raising the temperature to a predetermined temperature,
Hold at that temperature for no more than 30 minutes.

The mechanism by which a proper grain design is obtained by proper component design and two-step finish annealing, and the coarsening of crystal grains in the thickness direction in the pre-oxidation state is suppressed is presumed as follows. . By the first heating, TiC, Ti
Fine Ti-based compounds such as S and TiN are uniformly dispersed and precipitated in the matrix. The precipitated Ti-based compound exhibits a pinning action of suppressing the growth of crystal grains during the preliminary oxidation treatment. During the recrystallization growth process, crystal grains may partially grow large. The large grown crystal grains absorb adjacent small crystal grains in the subsequent crystal growth process, and become larger in size. As a result, a mixed grain structure in which small crystal grains are scattered at the grain boundaries of large crystal grains is obtained. With such a structure, it is impossible to stably obtain a state in which three or more crystal grains exist with respect to the plate thickness after the preliminary oxidation.

Therefore, in the first stage heating, the grain growth during recrystallization is temporarily stopped at the seventh stage of crystal growth immediately before the mixed grain structure. 500 ℃ of heated Fe-Cr alloy
When cooled to the following low temperature, the dispersion of the driving force for the movement of the crystal grain boundaries generated in the individual crystal grains is made uniform. As a result, when subjected to the second stage of reheating, the individual crystal grains grow evenly, and the mixture of crystal grains that are likely to occur in the secondary recrystallization is suppressed, and a grain-sized structure is obtained. Thus, the first stage heating temperature is 800-950 ° C., and the second stage heating temperature is 9
When the temperature is set to 00 to 1050 ° C. and the respective heating times are set within 30 minutes, generation of mixed grains which are likely to occur in the secondary recrystallization is suppressed, and a sized structure is obtained. Further, the coarsening of the crystal grains is also suppressed by the Ti-based compound precipitated by the first-stage heating.

[0012] The grain sized structure in the state of finish annealing needs to have a crystal grain size in a range of 5 to 6.
Even if the alloy material having a structure with a uniform crystal grain size is heated to a high temperature in the subsequent pre-oxidation process, uniform crystal growth proceeds overall, and some crystal grains absorb adjacent crystal grains. It does not become coarse. That is, regarding the crystal grain growth, the size of most of the recrystallized grains after primary recrystallization is d
It is generally said that when the size of a small number of recrystallized grains is D> 2d, only the small number of recrystallized grains grow large. It is considered that a mixed grain structure is formed due to the influence of the grain size after the primary recrystallization.

Further, in order to obtain a grain-sized structure by two-step finish annealing, it is necessary to regulate alloy components and their contents. Hereinafter, each alloy component will be described. C: Combined with Ti to form TiC, which is an effective alloying element for preventing coarsening of crystal grains. This effect is equivalent to 0.
It becomes remarkable at a C content of 005% by weight or more. However, in order to prevent precipitation of the austenitic phase and maintain good corrosion resistance, it is necessary to regulate the C content to 0.08% by weight or less. Si: An internal oxide particle is formed during the preliminary oxidation treatment, and has an effect of improving the adhesion strength of the oxide film. To secure this effect, 0.05% by weight or more of Si is required. However, a large amount of Si exceeding 1.0% by weight acts to reduce the thickness of the oxide film, and is not preferable because it lowers the adhesion strength of the oxide film. Mn: An alloy element effective for making the oxide film formed during the preliminary oxidation into a spinel type and improving the adhesion strength between the oxide film and the glass. When the Mn content is less than 0.10% by weight, formation of a spinel oxide is small. However, if the Mn content exceeds 0.80% by weight, the oxide film formed during the preliminary oxidation becomes too thick, and the adhesion to the base decreases.

S: becomes TiS and suppresses coarsening of crystal grains. If the S content is less than 0.005% by weight, the amount of TiS generated is small, and the effect of suppressing the crystal grain coarsening cannot be obtained. Conversely, if the S content exceeds 0.015% by weight, a large amount of sulfide-based inclusions serving as corrosion starting points are generated,
Deterioration of corrosion resistance. Cr: The Cr content is specified in the range of 16 to 25% by weight in order to give a thermal expansion coefficient similar to that of glass for a cathode ray tube. If the Cr content is less than 16% by weight, the coefficient of thermal expansion increases, and defects due to the difference in thermal expansion from glass tend to occur. On the other hand, if the Cr content exceeds 25% by weight, workability deteriorates. Ti: An alloy element necessary for producing fine Ti-based compounds such as TiC, TiS, and TiN. If the Ti content is less than 0.15% by weight, the amount of the required fine Ti-based compound to be produced is small, and a sufficient effect of suppressing the coarsening of crystal grains cannot be obtained. Conversely, a large amount of Ti exceeding 0.60% by weight
With the content, the surface properties of the alloy material deteriorate.

N: becomes TiN and suppresses coarsening of crystal grains. If the N content is less than 0.005% by weight, T
The amount of iN generated is small, and an effective crystal grain coarsening suppression effect cannot be obtained. On the other hand, when a large amount of N exceeding 0.02% by weight is contained, unevenness in oxidation tends to occur during the preliminary oxidation treatment, and it is difficult to obtain a uniform oxide film. Al: An alloy element necessary for enhancing the anchoring effect by forming internal oxide particles. In order to form effective internal oxide particles, 0.01% by weight or more of A
l. However, when a large amount of Al exceeding 0.30% by weight is contained, an oxide film formed by preferential oxidation of Al functions as a barrier layer and suppresses oxidation of other elements. As a result, the generated oxide film becomes thinner, and the adhesion to the base decreases.

[0016] Fe with defined alloying elements and their contents
The alloy undergoes two stages of finish annealing. The first-stage heating is performed in a temperature range of 800 to 950C, preferably 850 to 930C. When the heating temperature is lower than 800 ° C. or higher than 950 ° C., a primary recrystallized structure in which an appropriate fine Ti-based compound is uniformly dispersed and precipitated cannot be obtained. The second stage heating is performed in a temperature range of 900 to 1050C, preferably 930 to 1020C. 900 ° C. to make secondary recrystallization sufficiently performed by the second stage heating
The above heating temperature is required. However, when the heating temperature exceeds 1050 ° C., the crystal grains grow excessively, and the surface texture of the pressed product deteriorates.

The first and second heating times are set within 30 minutes in consideration of the growth of crystal grains. If the heating time is too short, a sufficient annealing effect cannot be obtained, and if it is too long, the productivity is reduced. Preferably, the first stage heating is 0.1 to 5
And the second-stage heating are set between 1 and 5 minutes. In addition, between the first-stage heating and the second-stage heating, 500
There is a cooling step of cooling to below ℃. The purpose of this cooling is to temporarily eliminate the driving force for moving the grain boundary generated in each crystal grain, and to make the variation uniform.

[0018]

EXAMPLES Four kinds of alloys shown in Table 1 were melted in a vacuum induction melting furnace. The thickness of each of the obtained alloys is 5.5 m
m, each hot-rolled sheet was annealed at 900 ° C., descaled, and cold-rolled at a rolling reduction of 70% to obtain a cold-rolled sheet having a thickness of 0.8 mm.

[Table 1]

Each cold rolled sheet is subjected to a two-stage finish annealing in which the first stage heating in the range of 750 to 1000 ° C., the cooling to lower the temperature to 500 ° C. or lower, and the second stage heating in the range of 850 to 1100 ° C. did. In addition, the comparative material which performed the one-step finish annealing in the range of 950-1050 degreeC as usual was also prepared. Each test material after annealing was press-formed into the shape shown in FIG. The dimension d _{1 of the} small diameter portion was set to 6 mm, the dimension d _{2 of the} large diameter portion was set to 12 mm, and the total height H was set to 10 mm. Each test material after the press working was subjected to a preliminary oxidation treatment of heating at 1150 ° C. for 40 minutes in a wet hydrogen atmosphere.
Thereafter, the test piece was sampled by cutting the curved portion shown in FIG. The surface of the test piece indicated by the arrow F was observed under a microscope, and the number of crystal grains in the thickness direction was counted. Table 2 shows the results of the survey.

[Table 2]

As is clear from Table 2, when the finish annealing is performed in only one stage, the crystal grains after the preliminary oxidation are coarsened, and no crystal grains having three or more crystal grains in the thickness direction can be obtained. Was. In contrast, appropriate amounts of Ti, C and N
To an alloy having a specified S content,
In the one-stage heating at 900 ° C and the two-stage heating at 900 to 1050 ° C, coarse grains did not appear in the curved part, and the structure in which three or more crystal grains existed in the plate thickness direction became stable. Obtained. When glass sealing was performed using the pre-oxidized test material, a sealed portion excellent in strength and airtightness was obtained.

Example 2 The test material No. 1 was subjected to two-stage annealing under various heat treatment conditions to change the grain size after annealing. From the experimental results, the first stage heating was 800-950 ° C,
When the second-stage heating was performed at 900 to 1050 ° C., it was found that a grain-sized structure in which the crystal grains after annealing were maintained in the range of particle size of 5 to 6 was obtained.

After the test materials having various crystal grain sizes are press-molded, they are heated to 1200 ° C. in a humid atmosphere having a relative humidity of 70%.
A preliminary oxidation treatment of heating for 0 minutes was performed. And observing the crystal structure in the thickness direction after the preliminary oxidation treatment,
When arranged in relation to the grain size after annealing, there was a relationship shown in Table 3 between the two. The crystal structure after the pre-oxidation treatment in Table 3 is obtained by counting the crystal grains by microscopic observation, denoting the structure in which three or more crystal grains are stably present in the sheet thickness direction as A, one in the sheet thickness direction B indicates a structure in which two crystal grains have an area ratio of 10% or less, C indicates a structure in which the area ratio of a portion where one or two crystal grains are observed in the thickness direction is 11 to 50%, and A structure in which the area ratio of a portion where one or two crystal grains were observed in the thickness direction exceeded 50% was evaluated as D.

[Table 3]

As is apparent from Table 3, when the grain size after annealing is adjusted to 5 to 6 by adjusting the annealing conditions, the crystal grains in the pre-oxidized state are stable in the thickness direction.
It became clear that it became the sealing alloy material which has a fine structure.

[0024]

As described above, according to the present invention, Fe-C having a prescribed content of Ti, C, N, S, etc. is used.
By subjecting the r-based alloy to the two-stage finish annealing, a material for a sealing alloy having a grain-size-regulated structure having a uniform grain size in the range of 5 to 6 is obtained. When this material is pre-oxidized, a fine structure in which three or more crystal grains are present in the thickness direction can be stably obtained. Therefore, the pre-oxidized sealing alloy has sufficient strength to support a shadow mask and the like, and forms a sealing portion having excellent airtightness.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a support stud manufactured from a rod material by cold forging and cutting.

FIG. 2 is a cross-sectional view of a support stud manufactured from a steel strip by press working.

FIG. 3 is a perspective view of a support stud manufactured according to the embodiment of the present invention.

[Explanation of symbols]

d ₁ : diameter of small diameter part d ₂ : diameter of large diameter part H: total height of support stud F: observation surface of crystal grain

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Inoue 4976 Nomura Minami-cho, Shinnanyo-shi, Yamaguchi Pref. Nisshin Steel Co., Ltd. Steel Research Laboratory (56) References JP-A-6-49599 (JP, A) JP-A Heihei 4-371550 (JP, A) JP-A-4-293751 (JP, A) JP-A-62-267449 (JP, A) JP-A-62-44526 (JP, A) JP-A-61-147852 (JP, A A) JP-A-6-158162 (JP, A) JP-B-63-19588 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 38/00-38/60 H01J 5 / 02 H01J 29/02 H01J 29/92

Claims (2)

(57) [Claims] 1. C: 0.005 to 0.08% by weight, S
i: 0.05 to 1.0% by weight, Mn: 0.10 to 0.8
0% by weight, S: 0.005 to 0.015% by weight, Cr:
16 to 25% by weight, N: 0.005 to 0.02% by weight,
Ti: 0.15 to 0.60% by weight, Al: 0.01 to
An alloy material for sealing, which is an Fe alloy containing 0.30% by weight, wherein crystal grains after finish annealing are sized to have a grain size of 5 to 6. 2. C: 0.005 to 0.08% by weight, S
i: 0.05 to 1.0% by weight, Mn: 0.10 to 0.8
0% by weight, S: 0.005 to 0.015% by weight, Cr:
16 to 25% by weight, N: 0.005 to 0.02% by weight,
Ti: 0.15 to 0.60% by weight, Al: 0.01 to
A Fe alloy containing 0.30% by weight is kept at 800 to 950 ° C. within 30 minutes, cooled to 500 ° C. or less, and further cooled to 900 ° C.
A heat treatment method for a sealing alloy, wherein a two-step finish annealing is performed at a temperature of ５０1050 ° C. within 30 minutes.