JPH09263891A - Iron-nickel alloy material, having high strength and low thermal expansion and excellent in punchability, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an Fe-Ni alloy material of high strength and low thermal expansion, minimal in the occurrence burr at the time of punching and having sufficient strength, causing no deformation at the time of punching, without causing cracking at the time of hot working. SOLUTION: The Fe-Ni alloy material has a composition containing, by weight, 0.003-0.03% C, <=2.0% Si, <=3.0% Mn, 30-50% Ni, 0.005-2.5% Nb, <=0.03% S, and 0.001-0.002% N and also containing, if necessary, <=3.0% Ti and <=50ppm B. This alloy material can be produced by performing the first-stage working at 800-1250 deg.C, the second-stage working at 800-1350 deg.C, hot rolling, and cold rolling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is advantageously used as a material for products to be punched, particularly for cathode ray tube electron gun electrodes in televisions and computer displays, shadow masks and lead frames, and parts of precision machines. The present invention relates to a high-strength, low-thermal-expansion Fe-Ni alloy material having excellent punchability and a manufacturing method thereof.

[0002]

2. Description of the Related Art For example, an electron gun of a cathode ray tube has many electrodes for narrowing, accelerating, and controlling an electron beam from a cathode. The material for the electrode has a low thermal expansion coefficient, Properties such as low flash generation during punching, high strength, and low outgassing are required. Conventionally, SUS304 has been mainly used as the electrode material, but nowadays, Fe-42 wt% Ni-based alloy having a low thermal expansion property is often used.

[0003]

However, in recent years, the precision of cathode ray tubes has increased, and in order to further improve the reliability of the electron gun, which is the heart of the cathode ray tube, the above-mentioned Fe-42 is used.
There are even more stringent requirements for wt% Ni-based alloys. In particular, the demands on the shape accuracy or assembly accuracy of parts have become strict. That is, this Fe-42 wt% Ni-based alloy is a material that easily causes "burrs" during press working such as punching. When using the electrode with this flash,
Since there is a possibility that the straightness of the electron beam may be impeded, it is necessary to prevent the occurrence of burrs during punching.

By the way, this flash can be removed by electropolishing the plate after punching, but there is a drawback that the surface of the processed product is contaminated with the electrolytic solution. That is, it is difficult to completely remove this stain even if it is annealed in a high-temperature reducing atmosphere, and the remaining stain becomes a residue from the surface of the component during use of the cathode ray tube, leading to a reduction in the life of the cathode ray tube. Further, since the Fe-42 wt% Ni-based alloy has low strength, there is a problem that components are likely to be deformed during assembly, which may cause color deviation of the cathode ray tube and adversely affect quality such as color purity.

In order to solve these problems, the above Fe-Ni
It is effective to add Nb to the base alloy and finely disperse the Nb compound by hot working. However,
When a Fe-Ni alloy containing a large amount of Nb is forged or hot-rolled, cracking may occur due to poor hot workability. When the cracks occur, it is necessary to remove the flaws or perform the slits in a later step, which causes a significant decrease in yield.

Therefore, an object of the present invention is to produce a high-strength, low-thermal-expansion Fe-Ni-based alloy material which has a small amount of flash during punching and has a strength such that it does not deform during punching, during hot working. Without doing so, we are proposing a manufacturing method.

[0007]

Means for Solving the Problems In order to achieve the above objects, the present invention provides (1) C: 0.003 to 0.03 wt%, Si: 2.0 wt% or less, Mn: 3.
0 wt% or less, Ni: 30 to 50 wt%, Nb: 0.005 to 2.5 wt%,
S: 0.03 wt% or less and N: 0.001 to 0.02 wt% are included,
We propose a high-strength, low-thermal-expansion Fe-Ni based alloy material that is excellent in punchability and consists of the balance Fe and unavoidable impurities. (2) And in addition to the composition of the above alloy material,
We propose a high-strength, low-thermal-expansion Fe-Ni alloy material having excellent punchability, which is characterized by containing Ti: 3.0 wt% or less and B: 50 ppm or less.

In the present invention, Nb is contained in the alloy material.
It is preferable to contain a compound. Further, in the present invention, the Nb compound has a maximum size of 20
It is preferably μm or less.

Next, the above alloy material of the present invention is (1) C:
0.003 to 0.03 wt%, Si: 2.0 wt% or less, Mn: 3.0 wt% or less, Ni: 30 to 50 wt%, Nb: 0.005 to 2.5 wt%, S: 0.03
wt% or less, N: 0.001 to 0.02 wt%, and if necessary, 3.0 wt% or less Ti and 50 ppm or less B, and the balance
Slab consisting of Fe and unavoidable impurities, 800-1250
In the temperature range of ℃, the total reduction of 15 to 40% is performed at least once in the first stage, then after heating to a temperature over 1250 ℃, the total reduction of 30 to 85 in the temperature range of 800 to 1350 ℃. % At least once in the second stage, (2) C: 0.00
3 to 0.03 wt%, Si: 2.0 wt% or less, Mn: 3.0 wt% or less,
Ni: 30 to 50 wt%, Nb: 0.005 to 2.5 wt%, S: 0.03 wt%
The following, including N: 0.001 to 0.02 wt%, and if necessary
A slab containing 3.0 wt% or less of Ti and 50 ppm or less of B, and the balance of Fe and unavoidable impurities was used at least once in a temperature range of 800 to 1250 ° C with a total reduction of 15 to 40%.
After stepwise processing and then heating to a temperature above 1250 ° C,
In the temperature range of 800 to 1350 ° C, at least one second stage processing with a total reduction of 30 to 85% is performed, and then hot rolling is performed. (3) Or, the slab is processed at 800 to 1250 ° C. Perform at least one first stage processing with a total reduction of 15 to 40% in the temperature range, then heat to a temperature over 1250 ° C, then 800
Perform at least one second stage working with a total reduction of 30-85% in the temperature range of ~ 1350 ° C, then hot-roll, at least one cold-roll and at least one annealing. Can be manufactured by

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION First, the reasons for limiting the component composition of the Fe-Ni alloy material of the present invention will be described. C: 0.003 to 0.03 wt% C is a component that forms a fine Nb compound and contributes to solid solution strengthening, precipitation strengthening and strengthening of the material by work hardening, but if it exceeds 0.03 wt%, electrical resistance increases. As a result, the conductivity is impaired, and a large amount of carbide is deposited to deteriorate hot workability, toughness and punchability. Furthermore, Fe-Ni
0.03 wt because the low thermal expansion that the alloys originally have deteriorates
%, Preferably 0.02 wt%. In order to secure high strength, the content is preferably 0.003 wt% or more, more preferably 0.005 wt% or more.

Si: 2.0 wt% or less Si is used as a deoxidizing agent in refining alloys.
If it exceeds 0 wt%, the hot workability deteriorates, so 2.0 wt%
Limited to the following. The content of the deoxidizing agent is preferably 0.01 wt% or more.

Mn: 3.0 wt% or less Mn is a solid solution strengthening component and is used as a deoxidizing agent in refining alloys, but if it exceeds 3.0 wt%, the deoxidizing effect is saturated, which is economically disadvantageous. In addition, since the hot workability is essentially reduced, it is limited to 3.0 wt% or less. In addition,
The content of the deoxidizing agent is preferably 0.01 wt% or more.

The above Si and Mn are solid solution strengthened without impairing the thermal expansion property originally possessed by the Fe-Ni alloy, and further, work hardening is large when cold working is performed, which greatly contributes to strengthening the material. It is an ingredient. In order to secure high strength, it is preferable that the total content of both components is 0.5 wt% or more. However, if it is too large, it becomes difficult to maintain the condition that the coefficient of thermal expansion in the temperature range of 30 to 450 ° C is 10 × 10 ^-6 / ° C or less, so the total amount of both components is 5.0 wt% or less. To do. The reason for maintaining the coefficient of thermal expansion below 10 × 10 ⁻⁶ / ° C. is that the level is high-definition cathode ray tube electron gun electrode,
This is because it is the minimum standard required for shadow masks, lead frames, and low thermal expansion materials for precision machinery parts.

Ni: 30 to 50 wt% If Ni is less than 30 wt%, martensite is formed even in the annealed state, and magnetic properties, thermal expansion properties, strength, and other physical properties are impaired. is necessary. If it exceeds 50 wt%, the saturation magnetic flux density and the electric resistance decrease, while the thermal expansion coefficient increases, and the square hysteresis is broken, which is also economically disadvantageous. Therefore, the upper limit is 50 wt%.

Nb: 0.005 to 2.5 wt% Nb is a component that characterizes the alloy of the present invention, and the Nb compound finely dispersed and precipitated contributes to the improvement of punchability. In order to impart high strength and low thermal expansion, at least 0.005 wt%, preferably 0.1 wt% or more,
More preferably, the content of 0.4 wt% or more is required. However, if it exceeds 2.5 wt%, the hot workability, toughness, and weldability are deteriorated, and the Nb compound becomes large and the punchability is impaired, so it is limited to 0.005 to 2.5 wt%.

S: 0.03 wt% or less S is an effective component for improving punchability, but 0.03 wt%
If it exceeds%, it segregates at the grain boundaries and the hot workability is impaired, so the content is made 0.03 wt%, preferably 0.003 wt% or less. In addition, in order to improve the punchability, it is preferable that the content of 0.002 wt% or more.

N: 0.001 to 0.02 wt% N is an essential component in the present invention. That is, it is an essential component element that constitutes a fine Nb compound,
It is necessary to contain 0.001 wt% or more. However, if a large amount of Nb compound is added, the solid solution temperature of the Nb compound becomes high, which adversely affects the dispersion and miniaturization of the Nb compound.
%, Preferably 0.005 wt% is the upper limit.

Ti: 3.0 wt% or less Ti has the effects of solid solution strengthening and precipitation strengthening.
The punching property is improved by finely dispersing and precipitating the composite compound. However, if it exceeds 3.0 wt%, the precipitates become coarse and the punchability deteriorates. It is preferably 1.0 wt% or less.

B: 50 ppm or less By adding B, hot workability is improved, and Nb or (Nb.
Accelerates precipitation of Ti) compound (Nb compound). However,
On the contrary, if added in excess of 50 ppm, the hot workability deteriorates, so B should be 50 ppm or less.

Further, in the present invention, in addition to the above components, C
Although r and Al can be contained if necessary, it goes without saying that the basic characteristics in the present invention can be obtained by the above component composition.

The alloy material according to the present invention is required to have the above-mentioned composition and to contain a carbide-based inclusion as an inclusion dispersedly contained in the material. The maximum size of this Nb compound is 20 μm. If the maximum diameter of the Nb compound exceeds 20 μm, the punching cross section has large burrs at the time of punching, as shown by D ₁ and D ₂ in FIG. 1, and the so-called punching property is significantly deteriorated. In the present invention, the diameter of the Nb compound (inclusion) is the average of the vertical and horizontal values of each particle when observed at 400 times, and in fact, 60 visual fields are observed, and the maximum value of each visual field is used. The average value was adopted.

Next, an alloy material having the above component composition, especially Nb alone (mainly Nb (C, N) -based compound) or
Combined addition of Ti and B (mainly (Nb, Ti) (C, N, B) compounds)
In order to realize excellent punchability in the Fe-Ni alloy material, it is necessary to finely disperse and precipitate the Nb compound. For that purpose, it is advantageous to subject the slab having the above composition to two-step processing at high temperature. Moreover, it is essential that this high-temperature two-step working be performed without causing cracks during hot working, and in the present invention, the above-mentioned requirements were satisfied by the following two-step pressing process.

That is, for the slab having the above composition, 80
The first stage press treatment in which a total reduction of 15 to 40% is performed at least once in the temperature range of 0 to 1250 ° C, and then
After heating to a temperature exceeding 1250 ° C, a second stage pressing process is performed in the temperature range of 800 to 1350 ° C at least once with a total reduction of 30 to 85%, to obtain a fine Nb compound Achieves dispersed precipitation.

Here, the temperature range in the first-stage pressing process is set to 800 to 1250 ° C. because cracking occurs during pressing below 800 ° C., and cracking occurs during pressing above 1250 ° C. Is. In addition, the total rolling reduction in the first-stage pressing process is set to 15 to 40% because the total rolling reduction is 15%.
If it is less than 40%, only the surface layer is recrystallized and recrystallization in the thickness direction becomes insufficient, while if it exceeds 40%, cracking occurs during pressing.

The heating prior to the second-stage press treatment was set to a temperature higher than 1250 ° C. because the effect of refining and dispersing the Nb compound is poor at 1250 ° C. or lower. And the second
The temperature range in the multi-step pressing process was set to 800 to 1350 ° C because cracking occurred during pressing above 1350 ° C, while
This is because even if the temperature is lower than 0 ° C, cracks may occur during pressing. The second-stage pressing temperature is preferably higher than the first-stage pressing temperature.

Further, the total rolling reduction in the second-stage press treatment is set to 30 to 85% because when the total rolling reduction is less than 30%, only the surface layer is recrystallized and recrystallization in the thickness direction is insufficient. This is because it is difficult to finely disperse and precipitate the Nb compound, and when it exceeds 85%, cracking occurs during pressing. The upper limit of the total rolling reduction is preferably 70
%, And more preferably 65%.

In the present invention, at least 1 is carried out after hot rolling and after descaling and surface flaw removal.
The thin plate may be manufactured by performing cold rolling more than once and annealing treatment at least once.

As a result of the above, the basic property expected in the present invention is that the Nb (C, N) compound is finely dispersed and precipitated in the material matrix. The compound is preferably C-based, and the maximum diameter is preferably 20 μm or less.

[0029]

EXAMPLE A molten steel having the composition shown in Table 1 was melted in an air induction furnace, and a steel ingot obtained by casting this molten steel was hot-pressed under the conditions shown in Tables 1 and 2. After performing the hot rolling according to the usual method, after descaling treatment and surface flaw removal treatment, primary cold rolling (reduction rate: 50% or more) and primary annealing treatment (950 ° C x 2 minutes) Then 2
A series of treatments including the following cold rolling (reduction rate: 50% or more) and secondary annealing treatment (950 ° C. × 2 minutes) were performed to produce a 0.4 mm-thick thin plate. The results of evaluating the punchability of the thus obtained thin plate and the presence or absence of cracks in hot pressing are shown in Tables 1 and 2.

In this embodiment, the morphology of the Nb compound is based on JIS G 0555, and is based on B-type inclusions (those in which discontinuous granular inclusions form a group in the processing direction). , And C-based inclusions (those irregularly dispersed without viscous deformation). Note that the punchability evaluation method uses a 2 mmφ punch and a clearance of 50 μm.
Punching was performed under m and the ratio of the fracture surface and the cut surface in the punched surface was evaluated. Specifically, as shown in FIG. 1, those having almost the same ratio of the fracture surface and the cut surface are ranked A, and from A to B, B to C, and C as the fracture surface ratio increases. The evaluation was made by changing to D ₁ and D ₂ .

[0031]

[Table 1]

[0032]

[Table 2]

As shown in Table 1, in the conforming examples of the present invention, the Nb compound has a size of 20 μm or less and is dispersed, so that it has a good punching property, and each of the conforming examples has a crack during hot pressing. Has not occurred. On the other hand, as shown in Table 2, in each of the comparative examples, whether the Nb compound is 20 μm or more,
Because it is not dispersed or the chemical composition is out,
The punchability was poor, and cracking occurred during hot press working, resulting in production stoppage.

[0034]

As described above, according to the present invention, high-strength and low-thermal-expansion Fe without causing cracks during hot working
A Ni-based alloy material can be advantageously manufactured. Moreover, it is possible to manufacture the Fe-Ni alloy material having excellent punchability with a high yield.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing evaluation criteria of punchability.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Saijin Fujiwara 4-2 Kojimacho, Kawasaki-ku, Kawasaki-shi, Kanagawa Pref.

Claims (7)

[Claims] 1. C: 0.003 to 0.03 wt%, Si: 2.0 wt% or less, Mn: 3.0 wt% or less, Ni: 30 to 50 wt%, Nb: 0.005 to 2.5 wt%, S: 0.03 wt% or less and N : 0.001 to 0.02wt% is included,
A high-strength, low-thermal-expansion Fe-Ni alloy material with excellent punchability that consists of the balance Fe and unavoidable impurities. 2. In addition to the component composition of the alloy material according to claim 1, it further contains Ti: 3.0 wt% or less and B: 50 ppm or less, high strength and low thermal expansion property excellent in punchability. Fe-Ni alloy material. 3. The high-strength, low-thermal-expansion Fe-Ni alloy material according to claim 1 or 2, which contains an Nb compound. 4. The high-strength, low thermal expansion Fe—Ni according to claim 3, wherein the maximum diameter of the Nb compound is 20 μm or less.
Series alloy materials. 5. C: 0.003 to 0.03 wt%, Si: 2.0 wt% or less, Mn: 3.0 wt% or less, Ni: 30 to 50 wt%, Nb: 0.005 to 2.5 wt%, S: 0.03 wt% or less, N : 0.001 to 0.02 wt%, and if necessary 3.0 wt
% Ti and 50 ppm B or less, and a slab composed of the balance Fe and inevitable impurities at a temperature of 800 to 1250 ° C at a total reduction of 15 to 40% at least once in the first stage. 800-1 after heating to a temperature above 1250 ° C
At least 1 with a total reduction of 30 to 85% in the temperature range of 350 ° C
A method for producing a high-strength, low-thermal-expansion Fe-Ni-based alloy material having excellent punchability, which is characterized by performing a second-stage processing. 6. C: 0.003 to 0.03 wt%, Si: 2.0 wt% or less, Mn: 3.0 wt% or less, Ni: 30 to 50 wt%, Nb: 0.005 to 2.5 wt%, S: 0.03 wt% or less, N : 0.001 to 0.02 wt%, and if necessary 3.0 wt
% Ti and 50 ppm B or less, and a slab composed of the balance Fe and inevitable impurities at a temperature of 800 to 1250 ° C at a total reduction of 15 to 40% at least once in the first stage. 800-1 after heating to a temperature above 1250 ° C
At least 1 with a total reduction of 30 to 85% in the temperature range of 350 ° C
Fe-Ni with high strength and low thermal expansion, which has excellent punchability, characterized by being subjected to a second stage of machining and then hot rolling.
Of manufacturing a base alloy material. 7. C: 0.003 to 0.03 wt%, Si: 2.0 wt% or less, Mn: 3.0 wt% or less, Ni: 30 to 50 wt%, Nb: 0.005 to 2.5 wt%, S: 0.03 wt% or less, N : 0.001 to 0.02 wt%, and if necessary 3.0 wt
% Ti and 50 ppm B or less, and a slab composed of the balance Fe and inevitable impurities at a temperature of 800 to 1250 ° C at a total reduction of 15 to 40% at least once in the first stage. 800-1 after heating to a temperature above 1250 ° C
At least 1 with a total reduction of 30 to 85% in the temperature range of 350 ° C
High strength low thermal expansion Fe-Ni system excellent in punchability, characterized in that it is subjected to a second stage working, then hot rolling, then at least one cold rolling and at least one annealing. Method of manufacturing alloy material.