JPH06264191A - Alloy material for sealing and heat treatment therefor - Google Patents

Abstract

PURPOSE:To produce a sealing material such as parts for supporting a shadow mask in which the coarsening of crystalline grains after preliminary oxidation is suppressed and high reliability is maintained over a long period. CONSTITUTION:An Fe alloy contg., by weight, 0.005 to 0.08% C, 0.05 to 1.0% Si, 0.10 to 0.80% Mn, 0.005 to 0.015% S, 16 to 25% Cr, 0.005 to 0.02S N, 0.15 to 0.60% Ti and 0.01 to 0.30% Al is subjected to two stage finish annealing of holding at 800 to 950 deg.C within 30min, cooling to <=500 deg.C furthermore holding at 900 to 1050 deg.C within 30min. The sealing material subjected to the final annealing has a graded structure in which the grain size is regulated to 5 to 6. Relatively many crystalline grains are present in the direction of the sheet thickness after preliminary oxidation, and supporting strength and airtightness are satisfied in the required shadow mask or the like.

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 Fe-42Ni-6Cr alloys and F alloys are used as alloys for sealing glass and ceramics.
e-42 to 50Ni alloy, Fe-29Ni-17Co alloy, Fe-18Cr alloy and the like are used. Among them, the Fe-18Cr alloy has a thermal expansion coefficient close to that of glass used in cathode ray tubes, and is therefore widely used as a shadow mask supporting component such as a support stud. As the support stud, a rod-shaped material which has been cold forged and cut into a cup having a cross-sectional shape shown in FIG. 1 has been used. However, this support stud 10
Has the drawback of requiring a large number of processing steps and of being heavy.

Recently, it has become possible to reduce the number of working steps with the progress of press working technology, and by press working a thin steel plate having a plate thickness of about 0.8 mm, the support stud 20 having the sectional shape shown in FIG. Is beginning to be used in the department. The thin steel sheet used for the support stud 20 is generally 950 to 50 after being subjected to melting, hot rolling, annealing and cold rolling.
Finish annealing is performed by heating to 1050 ° C. for 0.5 to 5 minutes. 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
A pre-oxidation treatment is performed in a wet hydrogen gas atmosphere for 60 minutes. By the pre-oxidation treatment, an oxide film effective for glass sealing is formed on the surface.

[0004]

The characteristics required for the support studs are that they have sufficient strength to support a relatively heavy shadow mask.
In this respect, the support stud 10 (FIG. 1) manufactured from the rod-shaped material by cold forging and cutting has a thick wall and has high strength reliability. On the other hand, the support stud 20 (FIG. 2) manufactured by pressing a thin steel plate is thin. When this support stud 20 is exposed to the high temperature at the time of pre-oxidation, recrystallization in the curved portion 21 that has undergone a large process progresses preferentially as compared with the flat portion 22. As a result, the crystal grains of the curved portion 21 become coarse, and a difference in strength may occur between the crystal portion and the flat portion 22 in which the coarsening of the crystal grains does not progress so much, and the curved portion 21 is likely to be deformed or cracked. Become.

When the crystal grains become coarse and penetrate through the plate thickness, the front and back of the plate thickness are connected by a single crystal grain boundary, and a slow leak due to the grain boundary diffusion of gas is likely to occur. as a result,
The airtightness of the support stud is reduced, and the performance of the cathode ray tube is significantly impaired. In this respect, in order to secure the necessary airtightness, it is required that the crystal grains after the pre-oxidation are stably 3 or more fine grains with respect to the plate thickness. However, with the conventional manufacturing method, it was difficult to stably obtain a fine grain structure in a pre-oxidized state. The problems of strength, airtightness, etc. are not limited to the support studs, and are the same for other sealing components such as lead frames for fluorescent display tubes manufactured from thin steel plates.

The present invention has been devised in order to solve such a problem, and a Fe-18Cr-based alloy in which the contents of Ti, C, N and S are specified is subjected to two-step finish annealing. As a result, a uniform grain size structure with uniform crystal grain size was obtained after finish annealing, and the crystal grain after pre-oxidation was stable with respect to the plate thickness and was excellent in reliability satisfying that it was 3 or more fine grains. It is an object to provide an alloy material for sealing.

[0007]

In order to achieve the object, the alloy material for sealing according to the present invention has C: 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.
02% by weight, Ti: 0.15 to 0.60% by weight, Al:
An Fe alloy containing 0.01 to 0.30% by weight, characterized in that the crystal grains after finish annealing are sized within a grain size range of 5 to 6. This sealing alloy material holds the Fe alloy having the above-mentioned composition at 800 to 950 ° C. for 30 minutes or less, cools it to 500 ° C. or lower, and further 900 to 1050
It is manufactured by performing a two-step finish annealing that is held at 30 ° C. for 30 minutes or less.

[0008]

[Function] In order for the sealing alloy such as the support stud manufactured by pressing to have sufficient shadow mask support strength and maintain excellent airtightness, it is necessary to suppress the growth of crystal grains during the pre-oxidation treatment. Assuming there is,
The present inventors investigated and studied changes in crystal grains after pre-oxidation from various viewpoints. As a method for suppressing the coarsening of crystal grains, it is conceivable to lower the heating temperature of the pre-oxidation treatment or shorten the heating time. However, the low-temperature or short-time pre-oxidation treatment has a drawback that a thin oxide film is formed and the sealing strength is lowered. Further, by containing Ti, which has a large affinity for C and N in the alloy,
It is also known to prevent coarsening by forming a carbonitride of Ti (see pages 360 to 361, Nihon Kogyo Shimbun Illumination, "Stainless Steel Handbook", December 25, 1980).

The inventors of the present invention also investigated the effect of adding Ti, and as for the suppression of the crystal grain coarsening of the support studs by press working, the crystal grains after pre-oxidation are stable with respect to the plate thickness and have three or more fine grains. It was confirmed that the requirements for grains were not satisfied, and that precipitation of carbonitride of Ti was not sufficient. The coarsening of crystal grains is greatly affected by the alloy component design and the structure after finish annealing. The present inventors experimentally confirmed that sizing the crystal grains after finish annealing effectively works to prevent coarsening of the crystal grains after the pre-oxidation treatment. Then, the Fe-Cr-based alloy in which the content of S was specified in addition to Ti, C, and N from the experimental results had a first step of 800
It was found that the coarsening of the crystal grains after the pre-oxidation is effectively suppressed when performing the two-step finish annealing in which the second stage is heated to 950 ° C and the second stage to 900 to 1050 ° C. In addition, in the one-step and two-step heating, after raising the temperature to a predetermined temperature,
Hold at that temperature for up to 30 minutes.

The mechanism by which a grain size controlled structure is obtained by proper component design and two-step finish annealing and grain coarsening in the plate thickness direction is suppressed in the pre-oxidation state 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 deposited Ti-based compound exhibits a pinning effect of suppressing the growth of crystal grains during the pre-oxidation treatment. In 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 to have a larger grain size. As a result, a mixed grain structure is formed in which small crystal grains are scattered at the grain boundaries of large crystal grains. With such a structure, a state in which three or more crystal grains are present with respect to the plate thickness cannot be stably obtained after pre-oxidation.

Therefore, in the first stage heating, the grain growth during recrystallization is temporarily stopped at the stage of crystal growth No. 7 just before the mixed grain structure is formed. Heated Fe-Cr alloy to 500 ° C
When cooled to the following low temperature, the variation in the driving force of the grain boundary movement generated in each crystal grain becomes uniform. As a result, when the second-stage reheating is performed, the individual crystal grains grow uniformly, and the mixed grains of the crystal grains that are likely to be generated in the secondary recrystallization are suppressed, so that the grain-structured structure is obtained. In this way, the heating temperature of the first step is 800 to 950 ° C, and the heating temperature of the second step is 9
When the heating time is set to 00 to 1050 ° C. and each heating time is set to 30 minutes or less, the generation of mixed grains that are likely to occur in 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 deposited by the first heating.

The grain size control structure in the finish-annealed state must have a crystal grain size in the range of 5 to 6.
Even if the alloy material with a uniform crystal grain size is heated to a high temperature in the subsequent pre-oxidation process, uniform crystal growth progresses, 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 is d after the primary recrystallization.
It is generally said that, when the size of a few recrystallized grains is D> 2d, only the few 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 size controlled structure by the two-step finish annealing, it is necessary to specify the alloy components and their contents. Hereinafter, each alloy component will be described. C: An alloying element that is effective in preventing coarsening of crystal grains by combining with Ti to form TiC. This effect is 0.
It becomes remarkable at a C content of 005% by weight or more. However, in order to prevent the precipitation of the austenite phase and maintain good corrosion resistance, it is necessary to regulate the C content to 0.08% by weight or less. Si: Formes internal oxide particles during the pre-oxidation treatment, and has the effect of improving the adhesion strength of the oxide film. To secure this action, 0.05 wt% or more of Si is necessary. However, a large amount of Si exceeding 1.0% by weight acts to thin the oxide film and reduces the adhesion strength of the oxide film, which is not preferable. Mn: This is an alloying element effective in making the oxide film produced during pre-oxidation into a spinel type and improving the adhesion strength between the oxide film and glass. When the Mn content is less than 0.10% by weight, the formation of spinel type oxide is small. However, if the Mn content exceeds 0.80% by weight, the oxide film formed during pre-oxidation becomes too thick, and the adhesion to the underlayer is reduced.

S: TiS to suppress coarsening of crystal grains. If the S content is less than 0.005% by weight, the amount of TiS produced is small, and the effect of suppressing crystal grain coarsening cannot be obtained. On the contrary, if the S content exceeds 0.015% by weight, a large amount of sulfide-based inclusions, which are the starting point of corrosion, are generated,
Deteriorates corrosion resistance. Cr: In order to give a coefficient of thermal expansion similar to that of glass for cathode ray tubes, the Cr content is specified in the range of 16 to 25% by weight. When the Cr content is less than 16% by weight, the coefficient of thermal expansion becomes large, and defects due to the difference in thermal expansion from glass are likely to occur. Further, if the Cr content exceeds 25% by weight, workability deteriorates. Ti: An alloying element necessary for producing fine Ti-based compounds such as TiC, TiS, and TiN. When the Ti content is less than 0.15% by weight, the required amount of fine Ti-based compound produced is small and a sufficient effect of suppressing coarsening of crystal grains cannot be obtained. On the contrary, a large amount of Ti exceeding 0.60% by weight
The content deteriorates the surface quality of the alloy material.

N: TiN is used to suppress coarsening of crystal grains. When the N content is less than 0.005% by weight, T
The amount of iN produced is small, and an effective grain coarsening inhibiting effect cannot be obtained. On the other hand, when a large amount of N exceeding 0.02% by weight is contained, uneven oxidation is likely to occur during the preliminary oxidation treatment, and it becomes difficult to obtain a uniform oxide film. Al: An alloying element necessary for enhancing the anchoring effect by forming internal oxide particles. 0.01% by weight or more of A to form effective internal oxide particles
1 is included. However, when a large amount of Al exceeding 0.30 wt% is contained, the oxide film formed by preferential oxidation of Al acts as a barrier layer and suppresses the oxidation of other elements. As a result, the oxide film produced becomes thin, and the adhesion to the base is reduced.

Fe with an alloying element and its content specified
The alloy undergoes a two stage finish anneal. The first stage heating is performed in the temperature range of 800 to 950 ° C, preferably 850 to 930 ° C. When the heating temperature is lower than 800 ° C. or higher than 950 ° C., a proper recrystallized structure in which an appropriate fine Ti compound is uniformly dispersed and precipitated cannot be obtained. The second heating is performed in the temperature range of 900 to 1050 ° C, preferably 930 to 1020 ° C. In order to sufficiently carry out the secondary recrystallization by heating the second stage, 900 ° C
The above heating temperature is required. However, if the heating temperature exceeds 1050 ° C., the crystal grains grow excessively and the surface texture of the press-formed product is deteriorated.

The heating time of the first and second steps is 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 lowered. Preferably, the first stage heating is 0.1 to 5
Minutes, the second stage heating is set between 1 and 5 minutes. In addition, between the first heating and the second heating, 500
A temperature lowering step of cooling to below ℃ is performed. The purpose of this cooling is to temporarily eliminate the driving force of the crystal grain boundary movement that has occurred in each crystal grain and to make the variation uniform.

[0018]

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

[Table 1]

Each cold-rolled sheet is subjected to a two-step 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. are performed. did. In addition, the comparative material which performed the one-step finish annealing in the range of 950 to 1050 ° C. was prepared as usual. After annealing, each test material was press-formed into the shape shown in FIG. The dimension d _{1 of the} small diameter portion was 6 mm, the dimension d _{2 of the} large diameter portion was 12 mm, and the total height H was 10 mm. After the pressing, each test material was subjected to a preliminary oxidation treatment of heating at 1150 ° C. for 40 minutes in a wet hydrogen atmosphere.
Then, the curved portion shown in FIG. 3 was sliced to obtain a test piece. The surface of the test piece indicated by the arrow F was observed under a microscope, and the number of crystal grains in the plate thickness direction was counted. The survey results are shown in Table 2.

[Table 2]

As is clear from Table 2, when only one step of finish annealing is performed, the crystal grains after the pre-oxidation become coarse, and those having three or more crystal grains in the plate thickness direction cannot be obtained. It was On the other hand, appropriate amount of Ti, C and N
Is added to the alloy whose S content is specified, and 800 to 950
With the one-stage heating at ℃ and the two-stage heating at 900 to 1050 ° C., coarse grains did not appear in the curved portion, and the structure in which three or more crystal grains were present in the plate thickness direction was stable. It was obtained. When glass was sealed using the pre-oxidized test material, a sealed part excellent in strength and airtightness was obtained.

Example 2: The test material No. 1 was subjected to two-step 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,
It was found that when the heating in the second step was set to 900 to 1050 ° C., a sized structure in which the crystal grains after annealing were maintained in the grain size range of 5 to 6 was obtained.

After press-molding the test materials having various grain sizes, the temperature was changed to 1200 ° C. in a humid atmosphere with a relative humidity of 70%, and
A pre-oxidation treatment of heating for 0 minutes was performed. Then, observe the crystal structure in the plate thickness direction after the preliminary oxidation treatment,
When arranged in relation to the sized state after annealing, there was a relation shown in Table 3 between the two. Regarding the crystal structure after the pre-oxidation treatment in Table 3, the crystal grains are counted by microscopic observation, and a structure in which three or more crystal grains are stably present in the plate thickness direction is A, one in the plate thickness direction or B is a structure in which two crystal grains have an area ratio of 10% or less, and C is a structure in which the area ratio of the portion where one or two crystal grains are observed in the plate thickness direction is 11 to 50%. The structure in which the area ratio of the portion where one or two crystal grains are observed in the thickness direction exceeds 50% was evaluated as D.

[Table 3]

As is clear from Table 3, when the grain size after annealing is adjusted to 5 to 6 by adjusting the annealing conditions, the grain size is stable in the plate thickness direction in the pre-oxidized state.
It has been found that the number of the alloys is more than one, and that the material is a sealing alloy material having a fine structure.

[0024]

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

[Brief description of drawings]

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

[Fig. 2] Cross-sectional view of a support stud manufactured from a band steel by press working.

FIG. 3 is a perspective view of a support stud manufactured according to an 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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Inoue 4976 Nomura Minami-cho, Shinnanyo-shi, Yamaguchi Nisshin Steel Co., Ltd. Steel Research Laboratory

Claims (2)

[Claims] 1. C: 0.005-0.08% 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:
16-25% by weight, N: 0.005-0.02% by weight,
Ti: 0.15 to 0.60% by weight, Al: 0.01 to
A Fe alloy containing 0.30% by weight, wherein the crystal grains after finish annealing are sized within a grain size range of 5 to 6 for sealing alloy material. 2. C: 0.005-0.08% 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:
16-25% by weight, N: 0.005-0.02% by weight,
Ti: 0.15 to 0.60% by weight, Al: 0.01 to
An Fe alloy containing 0.30% by weight is kept at 800 to 950 ° C. for 30 minutes or less, cooled to 500 ° C. or lower, and further 900
A heat treatment method for a sealing alloy, which comprises performing a two-step finish annealing at 1050 ° C for 30 minutes or less.