JP2002001517A - PRODUCTION METHODS OF CAST INGOTS TO BE PROCESSED TO Fe-Ni SYSTEM ALLOY MATERIAL - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide production methods of cast ingot to be processed to Fe-Ni system alloy material, by which the material's press formability is improved without deteriorating etching quality unevenness, etching factor and etching velocity. SOLUTION: After refining raw material(s) by using at least a process selected from AOD, VOD and VIM processes, the refined melt is cast and solidified as (a) consumable electrode(s), which is (are) further refined by ESR process to get (a) cast ingot(s) that contain(s) C, not more than 0.005 mass%, O not more than 0.0025 mass% and N not more than 0.003 mass%. Or the cast ingot thus obtained is further processed to soaking treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly used in the field of electronics-related products such as shadow mask materials and the like, and includes Fe-Ni based alloy materials containing 20-80% by mass of Ni, especially photoetching (hereinafter referred to as etching). ) And plastic working such as press forming and the like, which belong to the technical field of a method for manufacturing an ingot for manufacturing an Fe—Ni alloy material that exhibits excellent performance when used.

[0002]

2. Description of the Related Art 20-80%, especially 30-50% by mass
Fe-Ni-based alloys containing Ni are widely used in shadow mask materials, lead frame materials and the like after being subjected to an etching process due to excellent low thermal expansion characteristics. The shadow mask is manufactured by punching a large number of fine holes at a predetermined interval and shape in an Fe-Ni-based alloy thin plate material by etching, soft-annealing and press-forming into a predetermined three-dimensional curved surface shape. Is manufactured through ingot casting, hot rolling, cold rolling and the like.

When the shadow mask thin plate material after etching is observed with reflected light or transmitted light, a stripe pattern due to a large number of etching unevenness parallel to the rolling direction called "streak unevenness" may be seen. In addition to the line unevenness, various etching unevennesses are known. In these uneven portions, the fine holes are deviated from a predetermined diameter or shape, the etched surface is rough, and the like, which causes partial color tone and brightness disturbance of an image and scatters an electron beam. Doing so may cause a problem. In particular, in the case of a high-definition cathode ray tube used for a monitor of a computer which has been widely spread in recent years, the influence of the irregularities due to the unevenness of etching becomes remarkable. As described above, among the etching characteristics, local unevenness in etching, that is, overall uniformity of etching is the most important index.

[0004] Etching unevenness is caused by fine linear or chained non-metallic inclusions spread in the rolling direction, Ni, M
Segregation such as n causes a microscopic difference in the etching characteristics, and as a result, it looks like streaks with the naked eye. Conventionally, non-metallic inclusions, which are one of the causes of uneven etching, have been carefully selected for starting materials and argon oxygen decarburization (hereinafter referred to as A).
OD), vacuum oxygen decarburization method (hereinafter referred to as VOD),
Fe-Ni alloys have been produced by various refining methods such as a vacuum induction melting method (hereinafter referred to as VIM) (AOD,
VOD is exemplified in JP-A-62-174351.
IM is described in the embodiment in JP-A-5-222451). Also, the applicant of the present invention is disclosed in JP-A-8-143939,
A method of performing desulfurization refining in the presence of slag containing CaO while gas plasma heating a molten metal preliminarily refined under vacuum (hereinafter referred to as a plasma heating slag refining method) has been proposed.

For example, a typical invar alloy such as Fe
To manufacture a shadow mask material from a −36% Ni-based alloy, conventionally, for the purpose of suppressing etching unevenness, for example, C ≦ 0.01% and S ≦ 0.005 as impurity elements.
%, Al ≦ 0.05%, O ≦ 0.005%, etc., and the above-mentioned refining method has been implemented to achieve this. Among these, according to the AOD method and the VOD method, although the above-mentioned definition of the impurity element is satisfactorily satisfied, it has not been possible to sufficiently eliminate the occurrence of uneven etching due to component segregation accompanying solidification and the like. Also, Japanese Patent Application Laid-Open No. 61-2231 discloses a method for preventing uneven etching due to segregation of components such as Ni and Mn.
No. 88 etc. have been proposed.

[0006] Further, the molten metal obtained by the refining method or the like is cast into a consumable electrode, and the consumable electrode is further refined by a vacuum arc remelting method (hereinafter referred to as VAR) or an electroslag remelting method (hereinafter referred to as ESR). (Japanese Patent No. 2795703, Japanese Unexamined Patent Application Publication No.
No. 128662). JP-A-6-128662 mentioned above.
No. 1 is a method for making an ingot of an ingot of a Fe—Ni alloy, the first step of producing a consumable electrode having a C of 0.005% by weight or less, and a final ingot having a S of 0.002% by weight or less. , And a second step of producing a remelted ingot having O of 0.005% by weight or less. The first and second desirable steps include VIM and ESR, respectively. I have.

[0007]

As described above, various refining methods, re-melting methods, and diffusion heat treatments have been adopted, but the etching unevenness has not been sufficiently solved.
This has hindered the spread of i-type alloy shadow masks and the like, and further improvement is desired. On the other hand, since the shadow mask is formed by press-forming the etched thin sheet material into a predetermined shape as described above, the yield point is low from the viewpoint of press-formability, that is, the accuracy of the formed shape, and the springback during press-forming is low. Is required to be small. This press formability is often required for applications other than shadow masks.
The problem to be solved by the present invention is to provide a method for producing an ingot for producing an Fe—Ni-based alloy material, which improves press formability without lowering the conventional etching unevenness quality and etching rate.

[0008]

SUMMARY OF THE INVENTION The present invention achieves the reduction of nonmetallic inclusions and the suppression of segregation of Ni and Mn by ESR, and at the same time, regulates the content of C to guarantee the quality and etching rate of uneven etching. In addition, by reducing the contents of N and O together, the castability for producing an Fe-Ni-based alloy material having improved press formability by reducing the hardness after softening annealing without generating a new problem. This is a method for producing a lump.

[0009] That is, the present invention provides a method for producing a polymer by using 20-80% by mass.
In a method for producing an ingot for producing an Fe-Ni alloy material which contains Ni and is subjected to etching treatment, a melted and refined molten metal is cast into a consumable electrode, and the consumable electrode is subjected to electroslag remelting to obtain a C by mass. Is 0.005% or less, O is 0.0025% or less, and N is 0.003% or less.
In the present invention, the component of the ingot is S by mass of 0.002.
% Or less, and the refining of the raw materials is performed by a plasma heating slag refining method, an AOD method, a VOD method and a VI method.
The M method is desirable, and in the VIM method, it is particularly desirable to start with the dissolution of the raw materials. It is particularly effective to perform soaking in the state of an ingot.

[0010] In the present invention, the ingot by ESR produces a microstructure with a small segregation concentration difference by lamination solidification, thereby greatly suppressing etching unevenness due to segregation of components such as Ni and Mn, and refining slag. By the action, non-metallic inclusions such as oxides and sulfides are reduced, and uneven etching due to the inclusions is largely suppressed. Further, in the ingot, the quality of etching unevenness and the etching rate are guaranteed by regulating the C content, and the press formability is improved by regulating the contents of N and O.

The present inventors have disclosed the above-mentioned JP-A-6-1286.
Also in the material according to the method proposed in No. 62, when the content of N in the obtained ingot is high, formation of nitrides such as AlN and the like, and when the content of O is high, oxide Since it was found that the press formability was impaired by the formation, it was found that it was necessary to reduce N and O together, and furthermore, the ESR process was adopted and the O value was also reduced. As a result of experiments, it has been found that a reduction in hardness after softening annealing can be realized without causing other problems even if N is reduced.

JP-A-11-323499 discloses that Ni: 34 to 38%, Mn: 0.5% or less, and
l: 0.02% or less, N: 0.0030 to 0.0100
%, The balance being Fe and unavoidable impurities, and the smaller of the value obtained by dividing the content of soluble Al by 27 and the content of N by 14 is set to 0.00015 or less. In this way, the 0.2% proof stress of 260 N / mm by annealing at 800 ° C. or more (900 ° C. in the section of the detailed description of the invention).
An Fe—Ni-based alloy for a shadow mask of ² or less has been proposed. As an action of N and a reason for limiting its components, N improves the etching factor.
%, The effect of improving the etching properties (which is considered to be an etching factor) becomes insufficient.
When it exceeds 1%, harmful nitride-based inclusions are formed or pores filled with N ₂ gas are generated in the ingot, and the embodiment is described in an example using a vacuum melting furnace. . In Examples, O exceeds 0.0025% in each case, and no data of an etching test is listed.

Although the thin plate according to the present invention has N of 0.0030% or less, the problem that the etching factor is insufficient as shown in JP-A-11-323499 does not occur. In the present invention, the O content of 0.0025% or less and the obtaining of a dense steel ingot structure by the ESR method alone or in combination have an insufficient effect of improving the etching factor due to the shortage of N. It is considered to compensate for this. That is, the present invention reduces O
The experiment results show that the hardness after softening annealing can be reduced by applying the ESR process without causing a problem that the etching factor becomes insufficient even when the N content is reduced.

Japanese Patent Application Laid-Open No. 4-131354 discloses a method for producing an Fe—Ni-based alloy sheet material for a shadow mask.
It is proposed to manufacture by melting and refining by the electron beam cold hearth remelting method, and that if N exceeds 0.0030%, rolling scratches caused by non-metallic inclusions will occur.
JP-A-4-168248 is an example of electric furnace-ladle refining, where N precipitates nitride at grain boundaries in an Fe-Ni alloy,
In addition, it has a synergistic effect with C, S, O, and P, and N is 0.00
Japanese Patent Application Laid-Open No. Hei 4
No. 3,554,853 is an example using a converter-VAD (vacuum arc degassing) -VOD, and states that when N exceeds 0.005%, a large amount of metal nitride is generated and inhibits the etching piercing property. ing.

It should be noted that the Fe-Ni alloy referred to in the present invention is an alloy containing 20 to 80%, preferably 30 to 50%, and more preferably 34 to 48% of Fe and at least Ni. The alloy thin plate is limited to the one to be etched. However, if Kovar alloy or Ni is in the above range, it is added for deoxidation or strengthening of the alloy, for example, Si, Mn, Al, Mg, B, Cr, M
Other elements such as o, V, Nb, and Co may be included.

The reasons for limiting each element in the present invention will be described below (the contents are expressed by mass). If C is contained in a thin plate in excess of 0.005%, the etching rate will be extremely reduced, significantly impairing the productivity of the etching process,
In addition, since etching unevenness is easily generated, 0.005
% Or less. Preferably it is 0.004% or less, more preferably 0.003% or less. C is ES
Since it is not reduced by R, it is necessary that the consumable electrode itself be reduced to below these values.

The present inventors have conducted various studies on a method for improving the press formability of an Fe-Ni alloy, and as a result, have found that reduction of impurities in the alloy, particularly reduction of N and O, is effective. That is, N reacts with Al or the like added as a deoxidizer to form fine and numerous nitrides such as AlN, and O also forms a large number of oxides. Prevents crystal growth (pinning)
It was found that the crystal structure was refined to inhibit the decrease in hardness after annealing, thereby lowering press formability.
If N exceeds 0.003% in the thin plate, the hardness after softening annealing is increased and the press formability is greatly impaired. Therefore, N is limited to 0.003% or less. Desirably 0.0
02% or less. Since N cannot be reduced by ESR as in C, it is necessary that the consumable electrode itself be reduced to these values or less.

O forms oxides with various elements, generates non-metallic inclusions, and causes etching unevenness caused by the inclusions. O also causes crystal growth by the same action as that of AlN and the like. 0.0 to prevent press molding
It is limited to 025% or less. More preferably 0.0020
%, More preferably 0.0015% or less.
When S exceeds 0.002% in a thin plate, Mn
S is preferably limited to 0.002% or less, and more preferably 0.0015% or less, since it generates extensible non-metallic inclusions such as S and lowers the quality of uneven etching.

[0019]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to decarburization and degassing (degassing).
Since ingots are obtained by ESR having no function, it is important that the refining and casting methods for producing consumable electrodes to be used can advantageously reduce these to a sufficient level. Heated slag refining method, AOD
It is preferable to employ the VOD method, the VOD method and the VIM method.

In the plasma heating slag refining method, desulfurization refining is performed after low C, low O, and low N by preliminary vacuum refining, and these C, O, and N can be easily removed to a lower range than the electric furnace. Therefore, it is suitable for melting the electrode of the present invention. AOD
In the method, the decarbonization and degassing (de-N) reactions are progressed by lowering the partial pressure of CO under vigorous stirring by blowing Ar dilution gas in a low C region. Since both decarburization and denitrification can be easily performed to a lower range than the electric arc furnace, it is suitable for melting the electrode of the present invention. Since the VOD method is performed under vacuum, the decarburization and degassing (N) reactions are further promoted as compared with the AOD method, and are suitable for melting the electrode of the present invention.

In the VIM method, the temperature is raised or maintained as necessary, regardless of the presence or absence of an oxidizing heat, while the CO
Since the reaction and degassing (de-N) can be sufficiently performed, it is suitable for melting the electrode of the present invention. In the VIM method, it is particularly desirable to start from the dissolution of the raw material.
That is, a large amount of molten metal once melted has only a low effect of vacuum treatment such as degassing only by being exposed to vacuum for a long time.
When starting from dissolution by the M method, the raw materials are dissolved little by little while being exposed to vacuum, and pass through a state where the specific surface area is large until the dissolution is completed. ) And the like are greatly advanced.

In the present invention, as described above, it is effective to carry out soaking particularly in the state of an ingot. This can provide a shadow mask having excellent etching unevenness. For example, a diffusion treatment is performed in which the ingot is maintained at a temperature of at least 1150 ° C. or lower and a melting point or less, but depending on the size of the ingot, for example, at a diameter of 300 mm or more, is sufficiently held for at least 3 hours after soaking. Performing the soaking process at the stage of the ingot is economically advantageous because the surface area is small and the soaking process can be carried out in the atmosphere.

In the above-mentioned Japanese Patent Application Laid-Open No. 61-223188, concretely, hot-rolling is performed at 1150 ° C. to form a plate having a thickness of 5 mm, and then Ni is diffused by heat treatment at 1100 ° C. × 1 hour or more. It is disclosed that. However, since the surface area is extremely large in the high-temperature treatment of the plate material, it is necessary to generate a large amount of an oxide layer or to perform a heat treatment in a special atmosphere, which requires a great deal of cost and equipment.

In the present invention, the ESR step is an important step which is considered to be achieved alone or in combination with the reduction of O to reduce the hardness after soft annealing due to the reduction of N without causing the problem of the etching factor. However, in this step, it is necessary to secure an extremely low N, O atmosphere. For this reason, a thorough inert gas seal between the mold and the consumable electrode is used to shut off the re-dissolving atmosphere from the atmosphere, and then add a strong deoxidizing agent such as Al to the consumable electrode itself, or It is desirable to employ any of the methods of continuous or intermittent supply, or to use them in combination.

[0025]

EXAMPLES The present invention will be described below with reference to examples (contents are expressed by mass). (First Embodiment) In the process of arc furnace + AOD + ESR,
C: 0.003% or less, Fe-36% Ni-based alloy ingot was produced with the aim of N and O components shown in Table 1 (Examples of the present invention: 4 types, Comparative examples: 4 types). In any case, first, the materials are melted in an arc furnace, and the components at the time of tapping are oxidized and refined.
Almost C: 0.10%, S: 0.010%, N: 0.00
After adjusting to 6% and Ni: 36%, the hot water was discharged and shifted to AOD.

[0026]

[Table 1]

In the AOD, first, O ₂ in the bottom-blown gas is
Is performed in a state in which the ratio of O is higher than that of Ar, and the ratio of O ₂ is gradually reduced to de-C to a low C region, C is reduced to 0.005% or less. Was performed, Ar was blown in to remove N to approximately the target composition in Table 1 (each 0.002 to 0.004). Further, a refining was performed by adding a slag-making agent to reduce S to 0.002% or less. In addition, Al was used as a deoxidizing agent, and it was cast into a consumable electrode after reduction refining was completed, and the consumable electrode was subjected to ESR to form an ingot. In the ESR, the desulfurization of slag
Could remain 0.002% or less. In addition,
In the ESR, the gap between the mold and the electrode is sealed with an inert gas and Al is continuously added, so that the O value of the ingot is almost as shown in Table 1.
And the target composition. The C value of each of the ingots after ESR was about 0.005% or less, and the O and N values could be almost targeted components.

In the above AOD, C and N can be removed to a low C region in the initial decarburization period, and extremely low S can be achieved in the later reduction period. An Fe-36% Ni alloy for a mask was obtained. However, since the refractory on the wall of the AOD is magnesia-chromite brick and is highly contaminated by Cr, it was necessary to use a material having a low Cr value as a charging material in the arc furnace. The primary melting furnace may be a converter other than the arc furnace. Hot forging, hot rolling,
An alloy strip having a thickness of 0.15 mm was formed by cold rolling, the quality of etching unevenness and the etching factor were investigated, and the alloy strip was soft-annealed, and the hardness after annealing was measured.

Table 2 shows the results of the determination of the quality of the etching unevenness, the etching factor, and the press formability. here,
Judgment of press formability was based on the hardness after annealing for a specific value. From Table 2, it can be seen that there is no problem in the etching factor, and that the etching unevenness is slightly poor when the O of the ingot becomes 0.0035%, but the press formability of the ingot is N ≦ 0. 003% and O ≦ 0.
Very good or good at 0025%, but poor at 0.004% N and 0.0035% O.
It turns out that it is slightly bad in%.

[0030]

[Table 2]

The Vickers hardness of Comparative Example (e) was slightly higher than the specified value, but the Vickers hardness of Comparative Example (f) exceeded the specified value by about 5; It was determined that Comparative Examples (g) and (h) were even higher, and the press formability was determined to be poor. Invention Example (a)
In (d), the Vickers hardness was 5 or more lower than the specific value, and the press formability was judged to be very good or good. In addition, the ingot of the same lot as the ingot (a) was subjected to soaking at 1280 ° C., and an etching test was performed on a material obtained as an alloy band by plastic working under the same conditions as the ingot (a). It was confirmed that the material inserted in the soaking process further improved the quality of uneven etching.

(Second Embodiment) Next, an example in the case of manufacturing via VOD will be described. A Fe-36% Ni alloy was melted in an arc furnace, oxidized and refined, and then discharged to be transferred to VOD. The components at the time of tapping are C: 0.10% by mass, S:
0.010%, N: 0.006%, Ni: 36%. After moving to VOD, the residue is removed first, and the degree of vacuum is about 13.3 kPa.
At O ₂吹精to perform de-C, followed by O ₂ stops吹精further de-C at only evacuated degassing and de-N, 0 and C.
003%. N at this time was 0.002%.

Next, a slag-making agent and Al for deoxidation were added, deoxidation and desulfurization were performed at a degree of vacuum of 267 Pa, and S was reduced to 0.00.
After making 2% and O to 0.0022%, the consumable electrode was formed into an ingot, and the consumable electrode was subjected to ESR to form an ingot. Thereafter, plastic working was carried out in the same manner as in the first embodiment, subjected to an etching test, and Vickers hardness was measured after soft annealing. In addition,
The composition of the ESR ingot is C: 0.0029%, S: 0.0
015%, N: 0.0023%, O: 0.0024%,
Ni: 36%.

As a result, it was found that the etching unevenness, the etchin factor and the hardness after annealing were almost the same as those of the inventive example (b). In VOD, the degree of vacuum and A
Depending on the degree of agitation by r or the like, it is possible to proceed with de-N and de-O more than in the case of the AOD of the first embodiment. In addition, as the primary melting furnace, in addition to the arc furnace, the melting may be performed in a converter.
The value may be shifted to the VOD with the S value. Further, the reduction refining of VOD may be performed by VAD (vacuum arc degassing).

(Third Embodiment) Next, an example of manufacturing by a plasma heating slag refining method will be described. First, a molten Fe-36% Ni alloy melted in an arc furnace was received by a VIM, decarbonized and deoxidized by vacuum refining, and then received by a ladle having a gas plasma heating device. The components at the time of receiving the hot water are represented by C:
0.0035%, O: 0.0035%, S: 0.008
0%, N: 0.002%, Ni: 36%.

While adding a slag-forming agent to the molten metal, stirring by blowing Ar gas from a porous plug at the bottom of the ladle and gas plasma heating from the upper surface of the molten metal to remove S,
After removing the oxygen, the consumable electrode was cast, and the consumable electrode was subjected to ESR to form an ingot. The component of the ingot is C: 0.0035
%, O: 0.0018%, S: 0.0010%, N:
0.0022% and Ni: 36%. Thereafter, in the same manner as in the first embodiment, plastic working was performed, subjected to an etching test, and Vickers hardness was measured after softening annealing. As a result, it was found that substantially the same etching unevenness, etchin factor and hardness after annealing were exhibited as in Example (a) of the present invention.

The refining method by gas plasma heating mentioned here is a method in which slag refining is performed in a vessel having a gas plasma heating device to perform refining such as removal of O and removal of S. This refining method has no contamination of C from the heating means, and can add and melt a slag-making agent as needed, heat and maintain the molten metal, and stir by Ar or the like.
It has a feature that a refining reaction can be performed independently of an oxidizing heat in the VOD method or the like.

(Fourth Embodiment) Next, an example of manufacturing via a VIM will be described. First, Fe-36% N
The molten i-alloy is melted with a VIM, de-C, O-, and N-refined by vacuum refining, and then cast into a consumable electrode.
It was made into an ingot by SR. The component of the ingot is C: 0.00
32%, S: 0.0015%, N: 0.0021%,
O: 0.0021% and Ni: 36%. Afterwards the first
In the same manner as in the example, plastic working was performed, an etching test was performed, and Vickers hardness was measured after softening and annealing. As a result, it was found that the same non-uniform etching quality, etchin factor, and hardness after annealing were obtained, which were almost the same as those of the inventive examples (a) and (b).

[0039]

As described above, the manufacturing method of the present invention can prevent the uneven etching caused by the segregation of the components due to the rapid solidification of the ESR, and the non-metallic inclusions of the sulfide type and the oxide type by the ESR. , The unevenness of etching caused by inclusions is suppressed, the etching rate is set to low C, and the pinning is set to low N and O to realize good press formability. Thereby, without lowering the conventional etching unevenness quality, etching factor and etching rate,
It has become possible to provide an Fe-Ni-based alloy with improved press formability. In addition, if the ingot is soaked, a shadow mask with more excellent etching properties can be provided by sufficient diffusion of Ni and Mn.

Claims (3)

[Claims] 1. A method for producing an ingot for producing an Fe—Ni-based alloy material containing 20-80% by mass of Ni and being etched, wherein a melted and refined molten metal is cast to form a consumable electrode. By electroslag re-dissolving method,
A method for producing an ingot for producing an Fe-Ni-based alloy material, comprising: an ingot having a mass of C of 0.005% or less, O of 0.0025% or less, and N of 0.003% or less by mass. 2. The method for producing an ingot for producing an Fe—Ni alloy material according to claim 1, wherein the ingot has a S content of 0.002% or less by mass. 3. The refining of a molten metal for casting a consumable electrode is performed by at least one of a plasma heating slag refining method, a vacuum induction melting method, an argon oxygen decarburization method, and a vacuum oxygen decarburization method. 2. A method for producing an ingot for producing an Fe—Ni alloy material.