JP3410970B2 - Method for producing Fe-Ni alloy excellent in punching workability - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing method for stably manufacturing an Fe-Ni alloy having improved press punchability, which is suitable as an electronic material, particularly a material for a lead frame.

[0002]

2. Description of the Related Art Fe-Ni based electronic materials, especially 42% N
Since the i-Fe alloy (42Ni alloy) has a thermal expansion coefficient similar to that of glass or ceramics, it is used as an IC lead frame after punching or etching after being processed into a thin plate. Since this lead frame is required to have high dimensional accuracy, it is necessary to suppress burrs generated during press punching as much as possible. Furthermore, when burrs are generated, the life of the mold is shortened, and therefore improvement of punchability has become an urgent need in recent years.

[0003]

The punchability has been improved from the past. For example, JP-A-60-2559953, JP-A-60-255954,
In Japanese Patent Laid-Open Nos. 61-9552 and 64-11094,
It has been proposed to uniformly disperse non-metallic inclusions having a particle size of 3 μm or less in the structure. JP-A-4-346637,
In JP-A-6-184703 and JP-A-9-87808,
It is proposed to disperse fine MnS. However, these proposals do not consider the distribution state and shape of non-metallic inclusions and MnS. Even if such inclusions are present, if the distribution of the inclusions is offset or the shape is angular, the punchability may be impaired. In addition, JP-A-9-24
Although the number of MnS is specified in 9943, its shape is not considered important.

Furthermore, it is hard to say that means have been established for commercial production of alloys that satisfy these proposals. For example, in Japanese Unexamined Patent Publication No. 9-249943, only raw materials having high cleanliness are dissolved. Even if a raw material having a high degree of cleanliness is dissolved, it is common that the raw material usually contains several hundreds of ppm of oxygen inevitably, and it can be said that the deoxidation step is essential. In order to manufacture by a dissolution method that does not require a deoxidation step, a very expensive raw material is purchased, and in order to completely prevent an increase in oxygen concentration, an ultrahigh vacuum degree (for example, 10 ^{−5) is used.}
It is necessary to dissolve it at a torr), and it can be said that the cost is high in terms of both raw material and equipment.

Japanese Unexamined Patent Publication (Kokai) No. 9-87807 proposes that when the amount of non-metallic inclusions does not reach a predetermined amount, the oxygen concentration in the atmosphere is increased to promote oxidation and increase the number of inclusions. If it is over-oxidized, scum will be generated on the surface of the molten steel, and there is always the risk of entraining coarse inclusions, so it is not a good idea. As described above, in the conventional proposals, the deoxidizing method is uncertain, and the product yield is unavoidably low.

Therefore, the present invention has been made in view of the above circumstances.
Fe-Ni alloy with excellent punching properties
Purpose to provide a method for stable manufacturing
I am trying. Specifically, the object of the present invention is to have a particle size of 3 μm.
The following MnS and oxide-based inclusions with a particle size of 3 μm or less
3000-10000 pieces / mm in total during the tricks ^Two
Fe-Ni with excellent punching property, evenly dispersed at the density of
It is to provide a method for producing a base alloy.

[0007]

FIG. 1 shows a fracture surface after punching a material with a punch. A shear surface is formed on the side where the punch enters and a fracture surface is formed on the side where the punch exits. .
Plastic deformation occurs on the shear plane, and brittle fracture occurs on the fracture plane. Since a material having a certain degree of brittleness has better workability, burrs are likely to occur in a material having a large ratio of sheared surface to plate thickness. Therefore, the smaller the value of (shear surface / plate thickness), the better. Further, if the boundary between the shear plane and the fracture surface is disturbed, the ratio of the shear plane partially increases, so the linearity of the boundary between the shear plane and the fracture surface is also an index for evaluating punchability. The present inventors have found the following findings as a result of earnestly researching various influences on punchability based on the above principle.

(1) In order to improve punchability, M
In the cross section parallel to the rolling direction and the plate thickness direction, nS or oxide-based inclusions are 3000 to 1000 in total.
It is necessary to disperse uniformly with a density of 0 pieces / mm ² . (2) The particle size of MnS or oxide-based inclusions needs to be 0.01 to 3 μm in the final thin plate. If the particle size of the inclusions is less than 0.01 μm, it becomes difficult for the inclusions to become the starting point of fracture during punching. Conversely, the particle size of inclusions is 3μ
If it exceeds m, the range of fracture due to inclusions becomes too large, disturbing the linearity of the boundary between the shear plane and the fracture plane, and causing residual stress in the material to easily cause temporal deformation. The preferred range of the particle size of the inclusions is 0.1 to 3 μm, more preferably 0.1 to 2 μm. (3) If the distribution of inclusions as described above is less than 3000 pieces / mm in the cross section parallel to the rolling direction and the plate thickness, the punchability is not improved, and if it exceeds 10,000 pieces / mm ² , the shear cross section is increased. And the boundary of the fracture surface is disturbed. (4) The shape of MnS or oxide-based inclusions is preferably spherical. The spherical inclusions tend to be the starting point of fracture and are effective for lubrication with the mold. On the contrary, if the shape is sharp, it acts as abrasive grains on the die, and shortens its life.

Although the necessary elements as an alloy have been clarified as described above, it is commercially important to stably manufacture this alloy at low cost. Therefore, the present inventors
Performed various experiments to produce the above alloy,
The following findings have been obtained.

In order to disperse MnS having a particle size of 3 μm or less or oxide inclusions in the matrix at the product stage,
It is necessary to completely float up and remove the primary deoxidation product produced simultaneously with deoxidation. This is because the primary deoxidation product is relatively large and produces inclusions having a particle size of more than 3 μm when it becomes a thin plate. Further, if the primary deoxidation product is present, MnS is preferentially crystallized or precipitated there and removed. Therefore, also from this viewpoint, the primary deoxidation product must be completely removed. At this time, CaO-S
It is more effective to float the slag of iO ₂ system or CaO-Al ₂ O ₃ system on the surface of the molten metal and positively remove inclusions.

In order to disperse fine MnS, it is effective to make the composition of the oxide inclusions (secondary deoxidation products) produced by the temperature decrease during solidification to be MnO-SiO ₂ system. It turns out. The mechanism for fine dispersion of MnS is still unknown, but it is presumed as follows. That is, as the solidification progresses, S in the molten steel is dissolved in the MnO—SiO ₂ inclusions having a relatively high solubility and finely dispersed in the ingot. After that, when the ingot is forged and hot-rolled, it is reheated to produce MnS.
MnO-SiO ₂ is estimated that separated. However,
It is needless to say that the present invention is not limited by the presence or absence of such effects. Therefore, the elements of the deoxidizer used in the present invention are Si and Mn.

[0012] The onset Ming has been made based on the above findings, the melt of Fe-Ni-based alloy containing Ni 30 to 55 wt%, 50 ppm oxygen concentration by introducing the Si and Mn
After being lowered to the following temperature, casting is performed, hot rolling and cold rolling are performed, and in a cross section parallel to the rolling direction and the sheet thickness direction, MnS having a grain size of 0.01 to 3 μm and a grain size of 0.01 to Three
It is characterized in that oxide-based inclusions having a size of μm or less are uniformly dispersed in the matrix at a total density of 3000 to 10000 / mm ² .

In the above manufacturing method, it is undeniable that the primary deoxidation product floats slowly, and it takes some time to completely remove it. Therefore, the most effective method is not to produce a primary deoxidation product.
That is, immediately after the Fe-Ni has melted down, C content of 0.1%
C. O reaction is actively carried out by adding a small amount of oxygen to a reduced pressure atmosphere of at least 20 torr, and the oxygen concentration is 100 p
After controlling to pm or less, Si and Mn are added, for example, about 0.15% and 0.5%, respectively. By doing so, the production of relatively large deoxidation products can be avoided. In addition, when manufacturing high-grade steel with excellent cleanliness,
After vacuum melting, special melting represented by ESR (Electro Slag Remelting) or VAR (Vacuum Arc Remelting) is effective because a small amount of residual primary deoxidation product can be completely removed. Further, S is an important element that combines with Mn to generate MnS, and Al is M
It has a function of hindering fine dispersion of nS.

[0014] The onset Ming has been made based on the findings as described above, Fe-Ni containing Ni 30 to 55 wt%
After adjusting the Al content of the molten alloy to 0.002 wt% or less, pre-deoxidation with C under reduced pressure of 20 torr or less to make the oxygen concentration 100 ppm or less, and then the S concentration 0.0005 to 0 Adjusted to 0.02 wt%, Si and Mn
Was added to lower the oxygen concentration to 50 ppm or less, then cast, hot-rolled and cold-rolled to give a grain size of 0.01
˜3 μm MnS and oxide inclusions with a particle size of 0.01 to 3 μm in the matrix of 3000 to 10000 in total.
The feature is that they are uniformly dispersed at a density of pieces / mm ² . In this case, in order to reduce the Al content to 0.002% by weight or less, it is sufficient to oxidize and remove the Al by holding it in the air after melting. The amount of C added is 0.05
The amount of Si and Mn to be added is preferably 0.5 to 1.0% by weight. Further, the S content is adjusted by adding S to the molten metal or by desulfurization.

In order to finely disperse MnS, T
It was found that the addition of at least one of i and Zr was more effective. The reason for this is also inferred as follows, although it is currently being studied. First of all, oxygen is supersaturated during solidification and fine TiO ₂ or Z
rO ₂ inclusions precipitate. Then, it is speculated that S in the molten steel becomes supersaturated and MnS preferentially precipitates on the inclusions. However, this is also an assumption, and the present invention is not limited by the presence or absence of such an action.
In this case as well, the primary deoxidation product is a harmful substance that inhibits fine dispersion of MnS, and therefore must be actively removed. From the above findings, in the present invention, S
After adding i and Mn, it is preferable to add at least one of Ti and Zr in a total amount of 0.0001 to 0.01%.

By the above manufacturing method, Ni:
30-55%, S: 0.0005-0.02%, O: 5
0 ppm or less, the balance consisting of Fe and alloy elements and unavoidable impurities, and MnS having a grain size of 0.01 to 3 μm and oxidation having a grain size of 0.01 to 3 μm in a cross section parallel to the rolling direction and the plate thickness direction. It is possible to obtain a Fe—Ni based alloy in which the physical inclusions are uniformly dispersed in the matrix at a total density of 3000 to 10000 / mm ² .
The alloying elements include Si, Mn, C, Co and Cr, and the unavoidable impurities include N, Ca, Mg and
Nb, etc. The basis of the component composition limited in the present invention will be described below.

Ni: Ni is the most important component of the lead frame material. When Ni is less than 30% by weight, the coefficient of thermal expansion becomes large and the function as a lead frame material is lost. When Ni exceeds 55% by weight, not only the coefficient of thermal expansion becomes large, but also the cost of the alloy increases. Therefore, the Ni content needs to be 30 to 55%.

S: S is an important element in the present invention because it combines with Mn to form MnS and improves punchability. If the S content is less than 0.0005% by weight, a sufficient number of MnS particles cannot be generated, and the content is 0.02% by weight.
If the addition amount exceeds, hot workability is impaired,
It should be in the range of 0.0005 to 0.02%.

O: O in molten steel forms inclusions in combination with constituent components. If they are coarse, they disturb the punched fracture surface, so it is necessary to reduce them as much as possible. It has been confirmed that when the oxygen concentration exceeds 50 ppm, coarse primary deoxidation products are significantly generated. Therefore, the oxygen concentration in the final product is set to 50 ppm or less. Preferably 3
It is 0 ppm or less.

O after C deoxidation: under reduced pressure of 20 torr or less, deoxidation by addition of C is carried out to reduce the oxygen concentration, and then Si and Mn as deoxidizing agents are added. It has been confirmed that the Also,
Si in the state where the oxygen concentration after deoxidation exceeds 100 ppm
It has been confirmed that the addition of Mn and Mn produces a coarse primary deoxidation product. Therefore, the oxygen concentration after C deoxidation is set to 100 ppm or less. It is preferably 50 ppm or less. Also, if the degree of vacuum exceeds 20 torr,
Since the CO reaction does not proceed effectively, the degree of vacuum was set to 20 torr or less. It is preferably 1 torr or less.

It is preferable that the amount of Al is as small as possible. When Al exceeds 0.002%, the proportion of Al ₂ O ₃ in the deoxidation product increases, but the effect of finely dispersing MnS in such inclusions containing Al ₂ O ₃ is. Absent. Therefore,
The content of Al was 0.002% by weight or less. Ti and Zr are basically rich in the ability to finely disperse MnS, similar to Si and Mn. This is because MnS selectively crystallizes on fine TiO ₂ or ZrO ₂ that crystallizes during solidification. If it is less than 0.0001% by weight, the effect is not exhibited, and if it exceeds 0.01% by weight, the coefficient of thermal expansion of the alloy becomes large. Therefore, the total content of Ti and Zr is preferably 0.0001 to 0.01% by weight.

[0022]

EXAMPLES The present invention will be described in detail below based on specific examples. Thirteen types of steel ingots were manufactured by using the melting and casting processes shown in Table 1, and hot rolling and cold rolling were performed on them to obtain a thin plate having a thickness of 0.15 mm. In Table 1, # 1 to # 3, # 9 and # 10 are dissolution processes that do not produce a primary deoxidation product, and other # 3 to # 8 and #
11 to # 13 are processes in which the primary deoxidation product is generated and then float-separated. In Table 1, # 1 to # 8 satisfying all the conditions of claims 1 and 2 are examples of the present invention, and # 9 to # 13 not satisfying any of the conditions of claims 1 and 2 are comparative examples. Further, # 13 satisfies the condition of claim 1, but does not satisfy the condition of claim 2 , so that it is set as a comparative example.

The cross section of each test material in the rolling direction was cut and observed with an electron microscope, and the number of MnS observed on the cut surface was measured. The measurement results are also shown in Table 1. The punching test was carried out by setting a clearance of 3% of the plate thickness using a laboratory 500 kg precision die press and opening five 5 mm square holes at 10 mm intervals perpendicular to the rolling direction. The ratio of the shear surface / fracture surface on the fracture surface after punching was measured, and when the average value of 5 pieces was more than 0.75, it was ◯, 0.
When it was 75 or less, it was evaluated as x and is also shown in Table 1.

[0024]

[Table 1]

As can be seen from Table 1, it was confirmed that in each of the examples of the present invention, the punchability was excellent and the hot workability was also good. On the other hand, in # 9, since the S content was below the range specified in the present invention, the density of MnS was low, and as a result, the punchability was deteriorated. Also,#
In Nos. 10 and # 11, since the S content exceeds the range specified in the present invention, the density of MnS becomes too large, and as a result, the fracture surface is disturbed and the punchability is deteriorated, and the hot workability is deteriorated. Also deteriorated. Also, in # 12, Al
Since the content of exceeds the range specified in the present invention,
Al ₂ O ₃ is produced as a deoxidation product, and this product is M
The density of MnS decreased because it did not have the function of finely dispersing nS. In the case of # 13, the punchability was good because the condition of claim 1 was satisfied, but the thermal expansion coefficient increased because the Ti content was too large.

Regarding the measurement of the distribution state of MnS, after the buffing, the surface electrolyzed by the SPEED method was X-rayed.
Each sample 10 field of view was observed in a range of 50 μm × 50 μm by a line microanalyzer, the distribution of MnS was counted as a point by mapping, and the average was determined as the number per 1 mm square.

[0027]

As described above, according to the present invention, fine M
Fe-Ni with moderately dispersed nS and oxide inclusions
Since the alloy can be manufactured stably and at low cost,
It is expected that material defects due to burrs in the punching process of the lead frame material and defects due to handling will be eliminated, and the life of the mold will be greatly improved. It becomes possible to supply excellent parts for improving reliability and improving production efficiency.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a fractured surface after punching.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuya Ito 4-2 Kojima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Nihon Yakin Kogyo Co., Ltd. R & D Headquarters Technical Research Laboratory (56) Reference Japanese Patent Laid-Open No. 9-249943 (JP , A) JP 60-255953 (JP, A) JP 11-315354 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C22C 33/04-33/06 C22C 38/00-38/60 C21C 7/04-7/06

Claims (2)

(57) [Claims] 1. Fe-Ni containing 30 to 55% by weight of Ni
The Al content in the molten alloy was adjusted to 0.002 wt% or less.
After that, it was pre-deoxidized with C under reduced pressure of 20 torr or less.
Oxygen concentration to 100 ppm or less, then S concentration
Adjusted to 0.0005 to 0.02 wt%, Si and Mn
To reduce the oxygen concentration to below 50ppm and then cast
Manufactured, hot-rolled and cold-rolled, grain size 0.01
˜3 μm MnS and oxide-based media with particle size 0.01-3 μm
The total number of the existing materials in the matrix is 3000-10000
A method for producing an Fe-Ni-based alloy excellent in punching workability, characterized by uniformly dispersing at a density of pieces / mm ² . 2. Ti after the addition of Si and Mn
And at least one of Zr is 0.00 in total.
01-0.01% is added, The method according to claim 1,
A method for producing an Fe-Ni based alloy excellent in the punching workability as described .