JPH0377869B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD This invention relates to a method of manufacturing a wire made of zirconium copper, known as a heat-resistant copper alloy, by a dip forming method. Conventional technology Zirconium copper (hereinafter referred to as Zr copper) is made by adding a small amount of zirconium (approximately 50 to 2000 ppm) to copper.
It has excellent heat resistance, especially high temperature softening resistance, and its electrical conductivity is not so low compared to pure copper.
It has been widely used as a conductive material that requires heat resistance, such as diode lead pin material. The conventional manufacturing method for such Zr copper wire rods includes melting copper in a melting furnace, adding zirconium or a copper-zirconium master alloy to the molten copper, and casting the resulting molten alloy into an ingot. A common method is to hot-roll the ingot and then wire-draw it. By the way, zirconium is a material that is extremely easily oxidized, so it is necessary to use a vacuum or inert gas atmosphere to prevent oxidation during the melting and casting processes. Since melting and casting are performed separately, there is a problem in that the cost for preventing oxidation increases. Further, in the above-mentioned method, casting and rolling are performed separately, so there is a problem that energy costs and labor costs increase. Furthermore, in the above-mentioned method, it is necessary to remove oxide scale during hot rolling, which also causes an increase in costs. In addition, the above-mentioned methods generally have a slow solidification rate, which leads to segregation and quality variations. Incidentally, the dip forming method has recently been applied to the production of copper rough drawn wire. This dip heating method for producing rough drawn copper wire involves supplying a pre-melted pure copper molten metal (molten copper) into a crucible, and supplying a seed wire also made of pure copper into the crucible. After being immersed in water, the rod is continuously pulled vertically upward, thereby causing the molten copper to adhere and solidify around the seed wire to continuously obtain a cast rod with a diameter larger than the diameter of the seed wire. The rod is continuously hot-rolled into copper wire of the required diameter. In this deep forming method, by continuously supplying copper to the seed wire, the process from casting (solidification of molten copper adhering to the seed wire) to rolling can be performed completely continuously as a series of steps. It also has advantages such as good casting quality. Therefore, attempts were made to apply this deep forming method not only to the production of copper wire (pure copper wire) but also to the production of copper alloy wire, and the method was already proposed in Japanese Patent Publication No. 61-32110.
A crucible device for this purpose was also proposed in Utility Model Publication No. 61-24364. FIG. 2 shows the principle of the manufacturing process of copper alloy wire by such a dip forming method which has already been proposed. In FIG. 2, a pure copper raw material 1 such as electrolytic copper becomes molten copper in a melting step 2, and the molten copper is supplied to an immersion casting step 3 in a crucible. On the other hand, an alloying element additive material 4 such as zirconium is added to the molten copper in the crucible through an alloying element supply step 5, and a molten copper alloy is produced in the crucible. Further, a seed wire 6 made of, for example, pure copper is continuously supplied to the crucible in the immersion casting step 3 through a seed wire supply step 7. After the seed wire 6 is immersed in the molten copper alloy in the crucible, it is pulled up from the molten copper alloy and the molten copper alloy is deposited around the seed wire 6. Subsequently, in the cooling step 8, the copper alloy around the seed wire is The molten alloy solidifies into a cast rod, which is rolled to a desired diameter in a rolling process 9 to become a wire rod,
Further, the wire is wound up in a winding step 10. Furthermore, an example of the crucible device applied to the dip forming method for manufacturing copper alloy wire as described above, specifically an example of the crucible device proposed in the above-mentioned Utility Model Publication No. 61-24364, is described in the third section. As shown in the figure. In FIG. 3, a seed wire insertion hole 12 is formed in the center of the bottom of a crucible 11 made of a refractory material such as graphite, and a hollow barrier having an outer diameter smaller than the inner diameter is provided inside the crucible 11. The cylinder 13 is arranged vertically, and the inside of the crucible 11 is the barrier cylinder 13.
It is divided into a supply chamber 14 outside the barrier cylinder 13 and a seed line running chamber 15 inside the barrier cylinder 13. A communication hole 16 is formed in the lower part of the barrier cylinder 13, which communicates the inside and outside of the barrier cylinder 13.
Further, a protrusion 17 is formed on the outer peripheral surface of the barrier cylinder 13. In such a crucible device, the molten copper 19 melted in the melting furnace 18 is supplied to the supply chamber 14 of the crucible 11 via the supply path 20, and the alloying element additive material 4 is added to the supply chamber 14 by the addition device 21. A molten copper alloy 22 is produced.
The molten copper alloy 22 passes through the communication hole 16 into the barrier tube 1.
3 flows into the seed line running chamber 15 inside. In addition, in the seed wire running chamber 15, the seed wire 6 inserted into the seed wire insertion hole 12 continuously travels vertically upward, and after the seed wire 6 is immersed in the molten copper alloy 22, it immediately moves upward. The molten copper alloy 22 adheres and solidifies around the seed wire 6 as described above, and a cast rod 23 is obtained. In the above process, if a pure copper wire is used as the seed wire 6, a composite wire in which a copper alloy layer exists around the pure copper can be obtained. By using it as a seed wire and repeating the same process multiple times, it is possible to obtain a wire that is made of copper alloy up to the center. Problems to be Solved by the Invention When manufacturing Zr copper alloy wire by applying the previously proposed deep forming method as described above,
The simplest way to add alloying elements is to use pure zirconium material, but in this case, the segregation of zirconium in the Zr-copper alloy layer of the resulting wire is large, so it may be unsuitable depending on the purpose of use. It turned out that. In other words, the melting point of pure zirconium is around 1857°C, which is significantly higher than the melting point of copper (1083°C). Therefore, even if pure zirconium material is added to the molten copper in the crucible, its melting or diffusion is extremely slow, resulting in It is thought that it adheres to the surface of the seed wire while being dissolved, causing segregation. If such zirconium segregation occurs, workability will deteriorate significantly in the segregated area,
For example, when used as a diode lead pin material, a problem arises in that cracks occur from the segregated portions when processing such as header processing is performed. In order to solve this problem, instead of using pure zirconium as the zirconium additive material,
It is conceivable to use a copper-zirconium master alloy. In the copper-zirconium master alloy, its melting point is lower than that of pure zirconium, so when it is added to the crucible, it melts and diffuses into the molten metal more quickly than when pure zirconium is used, resulting in the zirconium as mentioned above. It is thought that segregation becomes less likely to occur. However, when the present inventors actually conducted an experiment to manufacture a Zr copper alloy wire by the dip forming method using a copper-zirconium master alloy, they found that even in that case, the copper alloy layer was formed quite frequently. It was found that zirconium segregation occurs. This invention was made against the background of the above circumstances, and it is possible to reliably and sufficiently prevent the occurrence of segregation of zirconium in the Zr copper alloy layer when manufacturing a Zr copper alloy wire by the dip forming method. The purpose is to provide a method. Means to Solve the Problems The present inventors have conducted various experiments and studies regarding the occurrence of segregation when a copper-zirconium master alloy is used as the zirconium additive material in the production of Zr copper alloy wire by the dip forming method. We discovered that the grain size of the copper-zirconium master alloy to be added and the zirconium concentration in the master alloy affected the occurrence of segregation, and as a result of further experiments and studies, we found that It was newly discovered that segregation is more likely to occur when the particle size is larger than a certain fixed particle size. In other words, it has been discovered that the occurrence of segregation can be prevented only when the grain size of the copper-zirconium master alloy used satisfies a certain inequality in which the zirconium concentration of the master alloy is a variable, and the present invention has been made based on this discovery. I arrived at the eggplant. Specifically, the method of the present invention supplies molten copper that has been melted in advance into a crucible, adds a zirconium-added material to the molten copper in the crucible, and generates a molten zirconium-copper alloy. The seed wire is continuously immersed in the molten zirconium-copper alloy in the crucible and pulled up, thereby adhering and solidifying the zirconium-copper alloy around the seed wire so that at least the surface layer contains zirconium in the range of 50 ppm to 2000 ppm. In producing a heat-resistant copper alloy wire material that is a zirconium copper alloy, the zirconium additive material added to the crucible is a copper-zirconium master alloy containing 1.0% by weight or more and 89% by weight or less of zirconium and having a grain size. y
The present invention is characterized in that the particle size (mm) of zirconium content x (wt%) satisfies the following formula: y≦-0.0417x+4.42. Effect: Target to be manufactured by the method of this invention
Zr copper alloy wire has a Zr copper alloy layer with a zirconium concentration of 50ppm (0.005%) or more than 2000ppm (0.2%)
The following shall apply. The heat resistance of Zr copper is insufficient for practical use when the zirconium concentration is less than 50 ppm.
On the other hand, even if a large amount of zirconium is contained, exceeding 2000 ppm, no further increase in the softening temperature can be expected, and this will only lead to an increase in cost. Therefore, as mentioned above, a Zr copper alloy wire having a copper alloy layer with a concentration in the range of 50 to 2000 ppm was targeted. In this invention, the Zr-copper alloy wire includes both a wire in which only the surface layer is a Zr-copper alloy layer and a wire in which the entire center is made of a Zr-copper alloy layer. In other words, as already mentioned, in the deep forming method, if pure copper is used as the seed wire, a wire (composite wire) whose surface layer is only a Zr-copper alloy layer can be obtained; If you draw a composite wire with a Zr-copper alloy layer formed on the surface layer and repeat the same deep forming using this as a seed wire, each time you repeat the deep-forming, the Zr copper becomes close to the center. The alloy layer can now be formed thickly, and on the other hand, if a Zr copper alloy wire is used as the seed wire from the beginning, the entire layer can be formed with one deep forming.
It is possible to obtain a wire with a Zr copper alloy layer,
The present invention includes any of these cases. In the method of this invention, when producing Zr copper alloy wire by the dip forming method as described above, the zirconium content is 1.0 as the zirconium additive material added to the molten copper in the crucible. Powder of copper-zirconium master alloy in the range of ~89% by weight, and the particle size y
(mm) is within the range that satisfies y≦−0.0417x+4.42 depending on the zirconium content×(wt%). In this way, the copper-zirconium master alloy powder particles containing zirconium within a specific range and having a particle size below a specific particle size according to the zirconium content are added to the molten copper in the crucible. When added, it quickly melts and diffuses and is evenly mixed into the molten copper, so that there is always molten Zr copper alloy with a uniform zirconium concentration around the seed wire running in the crucible. Therefore, segregation of zirconium is effectively prevented from occurring in the Zr copper alloy layer that has been pulled from the molten Zr copper alloy and adhered and solidified around the seed wire. Here, if the zirconium content of the copper-zirconium master alloy as the zirconium additive material is less than 1.0% by weight, the minimum zirconium concentration of the Zr copper alloy layer of the Zr copper alloy wire manufactured by the method of this invention
Even when obtaining 0.005%, it is necessary to melt more than 1/200 of the product weight of the copper-zirconium master alloy in a crucible. There is a risk that the melting of the master alloy during addition will be delayed and the master alloy powder will accumulate near the inlet, resulting in a situation where the charging has to be stopped. On the other hand, if the zirconium content of the copper-zirconium master alloy exceeds 89% by weight, its melting point will become high and it may adhere to the periphery of the seed wire unmelted, leading to segregation. Therefore, the zirconium content of the copper-zirconium master alloy was limited to a range of 1.0 to 89% by weight. On the other hand, if the particle size of the copper-zirconium master alloy powder does not satisfy the above formula, that is, if it is larger than the allowable particle size depending on the zirconium content, it should be It does not melt and diffuse, and may adhere and solidify around the seed wire unmelted, leading to segregation. Therefore, the particle size of the copper-zirconium master alloy powder must be within a range that satisfies the above formula depending on the zirconium content. Such a relationship between grain size and segregation depending on the zirconium content was discovered as a result of detailed experiments by the present inventors, and the experimental results will be described next. When manufacturing Zr copper alloy wire by the dip forming method using a crucible device as shown in Fig. 3, copper as a zirconium-added material is
Zr-copper alloy wire rods are created by varying the zirconium concentration and particle size of the zirconium master alloy powder particles, and are further drawn and heat-treated to finalize the diameter.
The wire rods were finished into 0.8 mm, and each wire rod was subjected to a hedging process, and the presence or absence of cracks in the processed portion was examined. Note that the hedging process here means a process in which the top portion 25 of the wire 24 and the portion 26 in the vicinity thereof are compressed and deformed into a disk shape to form a so-called diode lead pin shape, as shown in FIG. The results are shown in Table 1, and a graph plotting the results as a function of zirconium content and particle size is shown in FIG. In Table 1 and Figure 1, the x marks represent 5 out of 10,000 samples.
If a crack occurs with more than one sample,
Similarly, the circles indicate cases in which the number of samples in which cracks occurred is 4 or less out of 10,000 samples.

【table】

[Table] As is clear from Figure 1, there is a clear correlation between the frequency of crack occurrence and the zirconium content and grain size of the copper-zirconium master alloy.
The boundary line between cases where cracks occur in 5 or more out of 10,000 samples (x mark) and cases where cracks occur in 4 or less cases (○ mark) can be approximated by a straight line, and this straight line can be approximated by Approximation using the least squares method revealed that y=-0.0417x+4.42, where x (wt%) is the zirconium concentration and y (mm) is the particle size. It has been found that the occurrence of cracks in the hedging process described above is mainly caused by the segregation of zirconium in the Zr-copper alloy layer, and the number of cracks occurring in 10,000 samples is 4. If it is less than this, there is no practical problem.
Therefore, in this invention, y≦-0.0417x+4.42 is set as a condition for reducing the segregation of zirconium to a level that does not cause any practical problems. In carrying out the method of this invention,
The copper-zirconium master alloy powder having the above-mentioned zirconium content and particle size may be added as is to the molten metal in the crucible, or the powder may be added by filling a pure copper pipe. EXAMPLES Example 1 An example in which a crucible apparatus as shown in FIG. 3 was used to manufacture a Zr copper alloy wire having a Zr copper alloy layer containing 0.018% by weight of zirconium will be described below. An oxygen-free copper wire stripped to a diameter of 12.7 mm and running at a speed of 2000 Kg/hr was used as a seed wire, while pure molten copper was fed into the crucible, and 25% by weight of zirconium was added from the hopper to the molten copper in the crucible. -80 mesh of copper-zirconium master alloy containing (2.38
5000 kg/hr) was added at a rate of 2.4 kg/hr and passed through the seed line into the crucible.
A Zr copper coated 17mmφ rough drawn wire was manufactured at a speed of hr. This operation is then repeated for a total of three coatings, so that the area of the zirconium copper alloy layer in the cross section is about 90%, and the final coating is 8mmφ.
Finished with a rough line. After drawing the rough wire and finishing it with a diameter of 0.8 mm, it was heat-treated at 425°C for 1 hour to have mechanical properties of a tensile strength of 32 Kgf/mm ² and an elongation of 12%. It was processed using a hedging machine into the shape used for etc. As a result, out of 10,000 samples, there were no cracks. From this,
It is considered that the occurrence of zirconium segregation was almost completely prevented. Example 2 In Example 1, the copper-zirconium master alloy powder was directly added to the molten metal from the hopper, but in this Example 2, the same zirconium content and particle size as used in Example 1 was used. Copper-zirconium master alloy powder was filled into an oxygen-free copper pipe, and
A wire rod having a diameter of mmφ was used as the zirconium additive, and this was continuously added to the molten metal in the crucible at the same addition rate as in Example 1. Other conditions are the same as in Example 1. As in the case of Example 1, the results also confirmed that no cracks occurred during the hedging process. In each of the above embodiments, the crucible device shown in FIG. 3 is used, but the crucible device is essentially capable of immersing the seed wire into the molten Zr-copper alloy and pulling it up continuously. Of course, the structure is not limited to that shown in FIG. 3 as long as it has a structure. Effects of the Invention As is clear from the above embodiments, according to the method of the present invention, Zr
In manufacturing copper alloy wire rods, a copper-zirconium master alloy containing zirconium within a specific range as a zirconium additive material and having a particle size equal to or less than the particle size determined depending on the zirconium content is used. This effectively prevents the occurrence of zirconium segregation in the Zr-copper alloy layer, resulting in healthy Zr
It is possible to obtain a copper alloy wire rod, and therefore, by using the Zr copper alloy wire rod obtained by the method of the present invention, defects caused by segregation of zirconium, for example, during processing due to local decrease in workability, can be obtained. The occurrence of cracks can be effectively prevented.

[Brief explanation of drawings]

Figure 1 shows the zirconium content and particle size in a copper-zirconium master alloy as a zirconium-added material, obtained by the dip forming method.
A graph showing the relationship between Zr copper alloy wire and hedging workability. Figure 2 is a block diagram showing the principle of the process for producing copper alloy wire by the dip forming method. Figure 3 is a graph showing the relationship between Zr copper alloy wire and hedging workability. FIG. 4 is a longitudinal cross-sectional view showing an example of a crucible apparatus for producing copper alloy wire by the forming method, and FIG. 4 is a perspective view showing an example of a diode lead pin subjected to a hedging process. 4... Alloying element addition material, 6... Seed line, 11...
... Crucible, 19... Molten copper, 22... Molten copper alloy.

Claims (1)

[Claims] 1. Supplying pre-molten molten copper into a crucible, adding a zirconium-added material to the molten copper in the crucible to produce a molten zirconium-copper alloy, and zirconium in the crucible The seed wire is continuously immersed in the molten copper alloy and pulled up, thereby adhering and solidifying the zirconium copper alloy around the seed wire to form a zirconium copper alloy in which at least the surface layer contains zirconium in the range of 50 ppm to 2000 ppm. In manufacturing the heat-resistant copper alloy wire rod, the zirconium additive material added in the crucible is made of a copper-zirconium master alloy containing 1.0% by weight or more and 89% by weight or less of zirconium, and has a particle size of y (mm). 1. A method for producing a heat-resistant copper alloy wire, characterized by using powder particles whose zirconium content x (weight %) satisfies the following formula: y≦−0.0417x+4.42.