JP2008254023A - Method for producing copper material, and copper material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an inexpensive oxygen free copper material having a low softening temperature and a high electric conductivity, and to provide a copper material. <P>SOLUTION: As for this method for producing the copper material, in a method for directly producing the copper material from the molten metal of oxygen free copper using an upper drawing continuous casting apparatus, Nb is added to the molten metal of oxygen free copper stored by a molten metal storing means in the upper drawing continuous casting apparatus, and the ratio of Nb included in the molten metal of oxygen free copper is controlled to 0.0006 to 0.06 wt.%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a copper material, and more particularly to a method for producing an oxygen-free copper material.

  At present, most of various types of wires including copper wires are formed by a continuous casting and rolling method. First, the molten metal melted in the shaft furnace is supplied to an SCR-type or continuous rod (registered trademark) type continuous casting means to obtain a casting bar. Next, the casting bar is supplied to a hot rolling means connected to the continuous casting means and rolled to a predetermined outer diameter. Thereafter, the rolled material is cooled, and a rough drawing line is obtained (for example, see Patent Document 1).

  In the continuous casting and rolling method, each line of the melting step, the casting step, and the hot rolling step is continuous, which is an efficient method for producing the roughing wire and is an excellent method for productivity. The rough drawing wire thus obtained is then subjected to a cold drawing step and an annealing step to obtain a final product (for example, a copper wire). One component of this copper wire is tough pitch copper. Since tough pitch copper can use a mixture of scrap copper and electric copper, the raw material cost is low. Moreover, since tough pitch copper has a higher oxygen content than oxygen-free copper, it inevitably has a feature that the content of oxidized impurities is higher than oxygen-free copper. Further, as a method for producing oxygen-free copper, there is an upward pulling continuous casting method (upcasting method) in which molten copper is solidified in a mold disposed on the surface of the molten copper and continuously pulled upward. In recent years, this oxygen-free copper has been used for magnet wires for motors.

JP-A-6-240426

  By the way, industrial productivity can be improved by performing continuous annealing in the annealing process of copper wire manufacture (a cold wire drawing process and an annealing process are performed continuously). However, in this case, if the softening temperature of the annealed material is high, the annealing process takes time, and it is necessary to match the production speed of the cold drawing process with the production speed of the annealing process, which hinders the productivity of copper wire. Is done. Moreover, when the softening temperature of the material to be annealed is high, the thermal energy required for annealing increases, leading to an increase in product cost. Therefore, the softening temperature of the material to be annealed is lowered.

  In order to lower the softening temperature of the copper material, it is necessary to remove the impurity elements contained in the copper base material and increase the Cu purity. As a method for removing the impurity element, there are, for example, selection of a molten metal raw material (using a high-purity material), oxidation refining of the molten metal, reduction refining, and the like. However, this method of removing the impurity element is a method that is very expensive. For this reason, when tough pitch copper is used for the molten metal raw material, this method is extremely disadvantageous economically and cannot be said to be an industrially suitable method. Furthermore, in recent years, there has been a demand for oxygen-free copper that hardly causes gas voids during connection welding of magnet wires, and tough pitch copper is not suitable in this respect.

  On the other hand, as another method for lowering the softening temperature of the copper material, it is known that the concentration of a certain element among impurity elements contained in the copper base material may be lowered. One of the elements mentioned here includes sulfur (S) and lead (Pb) that are present in a solid solution state in Cu. In order to reduce the concentration of S and Pb solid-dissolved in Cu, measures such as vacuum degassing of the molten copper and heat treatment at a specific temperature on the copper bar after casting have been attempted. However, since these conventional measures cannot sufficiently reduce the concentration of S and Pb, the softening temperature of the copper material cannot be sufficiently lowered. Furthermore, with the spread of HEV vehicles in recent years, high conductivity is required for the conductor of the magnet wire from the viewpoint of increasing the efficiency of the motor.

  An object of the present invention, which was created in view of the above circumstances, is to provide an oxygen-free copper material manufacturing method and a copper material that are inexpensive, have a low softening temperature, and have high electrical conductivity.

  In order to achieve the above object, a method for producing a copper material according to the present invention is a method for producing a copper material directly from an oxygen free molten copper using an upward pulling continuous casting apparatus. Nb is added to the oxygen-free copper melt stored in the storage means, and the ratio of Nb contained in the oxygen-free copper melt is adjusted to 0.0006 to 0.06% by weight.

  Further, the method for producing a copper material according to the present invention is a method for producing a copper material directly from an oxygen free copper melt using an upward pulling continuous casting apparatus, wherein the copper material is stored in the molten metal storage means of the upward pulling continuous casting apparatus. Nb and at least one metal or alloy selected from Ti, Zr, Hf, V, Ta, Fe, B, Ca, Mg, or misch metal are added to the molten oxygen-free copper, and oxygen-free copper The ratio of each metal or alloy contained in the molten metal is adjusted to 0.0006 to 0.06% by weight.

  On the other hand, the copper material which concerns on this invention is a copper material manufactured using the manufacturing method of each copper material mentioned above, Comprising: A semi-softening temperature is 115 degrees C or less.

  According to the present invention, it is possible to obtain an excellent effect that an oxygen-free copper material that is inexpensive, has a low softening temperature, and has high conductivity can be obtained.

  Hereinafter, a preferred embodiment of the present invention will be described.

  The manufacturing method of the copper material which concerns on one preferred embodiment of this invention manufactures a copper material directly from an oxygen free molten copper using an upward pulling continuous casting apparatus.

  Specifically, first, Nb is added to the oxygen-free molten copper stored in the molten metal storage means (for example, a melting furnace) of the upward pulling continuous casting apparatus. At this time, the addition amount is adjusted so that the proportion of Nb contained in the oxygen-free copper melt is 0.0006 to 0.06 wt%. Nb is a metal having a large affinity for S (hereinafter referred to as a sulfur affinity metal). Nb to be added may be either a simple substance of Nb or a simple substance of an alloy containing Nb.

  Next, the oxygen-free copper molten metal containing Nb is pulled upward from the mold disposed on the surface of the molten copper and solidified to continuously produce an oxygen-free copper roughing material (for example, roughing wire). Thereafter, the roughing material is appropriately subjected to cold surface reduction to obtain a final wire diameter, and a copper material (for example, copper wire) having a semi-softening temperature of 115 ° C. or lower is obtained. A product obtained by subjecting this copper material to annealing treatment is the final product. The semi-softening temperature mentioned here is a temperature at which the tensile strength of the copper material after heating for 60 minutes becomes half the tensile strength of the copper material before heating.

  The oxygen-free copper referred to here means pure copper having an oxygen content of 10 ppm or less and containing inevitable impurities.

  Sulfur affinity metal content (Nb content) is defined as 0.0006 to 0.06 wt%, preferably 0.0006 to 0.055 wt%, more preferably 0.001 to 0.05 wt%. This is because when the Nb content is less than 0.0006% by weight, S and Nb dissolved in the copper base material do not sufficiently react and the effect of lowering the softening temperature cannot be obtained sufficiently. On the other hand, if the Nb content exceeds 0.06% by weight, the solid solution amount of Nb dissolved in the copper material increases too much, and the softening temperature of the copper material rises conversely to obtain a desired semi-softening temperature. It is because it is not possible.

  Also, the semi-softening temperature is defined as 115 ° C. or lower, preferably 100 ° C. or lower, more preferably 95 ° C. or lower because the effect of reducing the softening temperature of the copper material is not sufficient when the semi-softening temperature is 115 ° C. or higher. It is.

  Here, the reason why the softening temperature of the copper material according to the present embodiment is greatly reduced is considered as follows.

  Ordinary oxygen-free copper has about 10 ppm of S dissolved therein, and this S is said to be a major factor that raises the softening temperature of the copper material. Therefore, in the manufacturing method according to the present embodiment, Nb is added to the molten oxygen-free copper immediately before casting at a predetermined ratio. When this Nb reacts with S that is dissolved in the oxygen-free copper melt, S precipitates as a sulfide (for example, NbS), and the solid solution amount of S is reduced. In addition, Nb serves as a nucleus when the oxygen-free molten copper is solidified and recrystallized, so that the recrystallization generation energy of oxygen-free copper can be lowered. It is considered that the softening temperature of the copper material can be greatly reduced by these combined effects.

  The form of the roughing material used in the manufacturing method according to the present embodiment and the finally obtained copper material is not particularly limited as long as it can be formed by surface reduction processing. For example, the shape is linear or plate-like. Or any of the stripes.

  Next, the operation of the copper material according to the present embodiment will be described.

  Usually, a copper wire obtained by subjecting a rough drawn material to cold surface reduction, drawing, and drawing is a high-hardness wire (for example, hard copper wire) by work hardening. For this reason, when annealing normal copper wire, particularly when annealing annealing, high temperature and long time heat treatment is required.

  However, the copper material obtained by the manufacturing method according to the present embodiment adds Nb to the oxygen-free molten copper used as a raw material for the copper material so that the content thereof is 0.0006 to 0.06% by weight. is doing.

  Here, since Nb which is a sulfur affinity metal is a metal with strong reactivity with oxygen, it reacts with oxygen in air | atmosphere and oxidizes easily. Therefore, if the time from adding Nb to the tough pitch copper molten metal until it is actually used for casting is long, the time for Nb to be exposed to the air becomes long, and Nb is oxidized in a large amount, resulting in an addition loss. Therefore, it is important to suppress the reaction between Nb and oxygen in the atmosphere. In the manufacturing method according to the present embodiment, the desirable timing for adding Nb to the molten copper is immediately before casting. The Nb addition form may be a direct addition of Nb metal, but it is preferable to add an alloy with a copper base material. As a result, the oxidation of Nb can be suppressed as described above. Moreover, the variation in weighing of the added amount can be suppressed, and as a result, the accuracy of the Nb content can be increased.

  The copper material obtained by the manufacturing method as described above uses tough pitch copper and has a lower softening temperature than an oxygen-free copper material manufactured by a conventional method (hereinafter referred to as a conventional copper material) (for example, Semi-softening temperature is 110 ° C. or lower). For this reason, the copper material of the present embodiment can be sufficiently annealed at a lower temperature. Therefore, when performing annealing annealing, the copper material of the present embodiment can be annealed at a lower temperature and in a shorter time than a conventional copper material. As a result, productivity of the copper material is improved, and energy required for manufacturing the copper material can be reduced.

  The copper material of the present embodiment is made of oxygen-free copper excellent in connection weldability, and since its softening temperature is significantly lower than that of conventional copper materials, the production cost of the final product becomes low, It is a copper material with very high industrial value.

  Next, another embodiment of the present invention will be described.

  In the method for producing a copper material according to the previous embodiment, only Nb is used as the sulfur affinity metal.

  On the other hand, the method for producing a copper material according to another preferred embodiment of the present invention uses at least one metal other than Nb as the sulfur affinity metal. In other words, the copper material manufacturing method according to the present embodiment is a method in which a part of Nb added as a sulfur-affinity metal in the copper material manufacturing method according to the previous embodiment is replaced with another metal. is there. The method for producing a copper material according to this embodiment is the same as the method for producing a copper material according to the previous embodiment, except that there are multiple types of sulfur-affinity metals added to the oxygen-free molten copper. is there. Therefore, only the differences from the manufacturing method according to the previous embodiment will be described below.

  In the method for producing a copper material according to the present embodiment, Nb and Ti, Zr, Hf, V, Nb, Ti, Zr, Hf, V, At least one metal (or alloy) selected from Ta, Fe, B, Ca, Mg, or Misch metal is added. At this time, the addition amount is adjusted so that the ratio of Nb and at least one metal (or alloy) contained in the oxygen-free copper melt is 0.0006 to 0.06 wt%. This at least one metal (or alloy) is also a sulfur-affinity metal like Nb. The added Nb and at least one metal (or alloy) are either a mixture of simple Nb and at least one simple metal, or a mixture of an alloy containing Nb and an alloy containing at least one metal. May be.

  Also in the copper material obtained by the manufacturing method according to the present embodiment, the same effects as the copper material obtained by the manufacturing method according to the previous embodiment can be obtained.

  In addition, in the copper material of the present embodiment and the copper material of the previous embodiment, if the content of Nb is the same, the amount of the sulfur-affinity metal added is slightly increased, so the copper material of the present embodiment is more The softening temperature is slightly higher than that of the copper material of the previous embodiment. However, regarding the heat resistance of the copper material, the copper material of the present embodiment is better than the copper material of the previous embodiment. This is because at least one kind of metal added together with Nb reacts with S dissolved in the oxygen-free copper molten metal to contribute to lowering the softening temperature of the copper material, and to improve the heat resistance of the copper material. It is because it contributes to raising.

  As described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various other things are assumed.

  Next, although this invention is demonstrated based on an Example, this invention is not limited to this Example.

  Using an upcast continuous up-drawing continuous casting apparatus, a rough drawn wire made of oxygen-free copper and having a diameter of 8 mm was produced. The constituent material of the rough drawn wire is obtained by adding a sulfur-affinity metal at a predetermined ratio to an oxygen-free molten copper. The rough drawing wire was repeatedly subjected to cold surface reduction processing and annealing treatment as appropriate, and copper wires having a diameter of 0.5 mm were prepared (Sample 1 to Sample 17).

  For sample 1, no sulfur-affinity metal was added (Comparative Example 1).

About samples 2-6, only Nb was added as a sulfur affinity metal, respectively.
What contains 0.006% by weight of Nb (Example 1),
What contained 0.012% by weight of Nb (Example 2),
What contained 0.04% by weight of Nb (Example 3),
What contains 0.06% by weight of Nb (Example 4),
A sample containing 0.0005% by weight of Nb was defined as (Comparative Example 2).

For Samples 7 to 16, a total of two Nb + α species were added as sulfur-affinity metals.
What contained 0.012Nb + 0.003Ti (the total of the two types was 0.015% by weight) (Example 5),
What contained 0.012Nb + 0.006Zr (the total of the two types was 0.018% by weight) (Example 6),
What contained 0.012Nb + 0.01Hf (2 types total is 0.022 weight%) (Example 7),
What contained 0.012Nb + 0.03V (2 types total is 0.042 weight%) (Example 8),
What contained 0.012Nb + 0.02Ta (the total of the two types was 0.032 wt%) (Example 9),
What contains 0.012Nb + 0.003Fe (the total of the two types is 0.015% by weight) (Example 10),
What contained 0.012Nb + 0.002B (two types total is 0.014 weight%) (Example 11),
What contains 0.012Nb + 0.002Ca (the total of the two types is 0.014% by weight) (Example 12),
What contains 0.012Nb + 0.002Mg (total of two types is 0.014% by weight) (Example 13),
A product containing 0.012Nb + 0.002MM (Misch metal; the total of the two types was 0.014% by weight) was defined as (Example 14).

  Sample 17 produced a drawn wire of φ8 mm made of tough pitch copper using a continuous casting and rolling method (SCR method). The constituent material of the rough drawn wire is obtained by adding 0.003% by weight of Ti, which is a sulfur-affinity metal, to the oxygen-free molten copper. This rough drawing wire was subjected to cold drawing and annealing treatments as appropriate to produce a copper wire having a diameter of 0.5 mm (conventional example 1).

  Softening tests were performed using the copper wires of Examples 1 to 14, Comparative Examples 1 and 2, and Conventional Example 1, and the softening characteristics were evaluated. The results are shown in Table 1. Here, the evaluation of the softening characteristics was performed using the semi-softening temperature. Moreover, about each copper wire, the complete annealing process (process which softens until the intensity | strength of a copper wire does not fall any more) was performed, and the electrical conductivity measurement was also implemented.

  As shown in Table 1, each copper wire of Examples 1 to 14 has a sulfur-affinity metal content in the range of 0.0006 to 0.06% by weight, and the production of the copper wire according to the present invention. I was satisfied with the method. The semi-softening temperature of each copper wire of Examples 1 to 14 is 115 ° C. or lower (74 to 115 ° C.), and the semi-softening temperature of each copper wire of Comparative Example 1 to which no sulfur-affinity metal (Nb) is added. Compared with (135 ° C.), the semi-softening temperature also decreased at 20 ° C. or higher (about 20 to 61 ° C.). Since the semi-softening temperature of the copper wire of Example 4 is 115 degreeC, it can confirm that the upper limit of content of a sulfur affinity metal is 0.06 weight%. In particular, the copper wires of Examples 1 to 3 and 5 to 14 are more preferable because the semi-softening temperature is 96 ° C. or lower.

  On the other hand, since the Nb content of the copper wire of Comparative Example 2 is too small as 0.0005% by weight, the effect of lowering the softening temperature of the copper wire is not sufficient, and the copper of Comparative Example 1 containing no Nb is added. The decrease in semi-softening temperature compared to the line was only 14 ° C (121 ° C).

  The electrical conductivity of each copper wire after the complete annealing treatment was 101.5% IACS or higher in Examples 1 to 14 having a low semi-softening temperature, but Comparative Examples 1 and 2 having a high semi-softening temperature were 101. Less than 5% IACS. Moreover, when the copper wire which is a sample and the front-end | tips of a copper wire were faced | matched and TIG-welded, in the case of the copper wire of a prior art example, the void was formed in copper, Examples 1-14 of this invention, and In Comparative Examples 1 and 2, no void was observed.

  From the above, a sulfur-affinity metal is added to the oxygen-free copper melt, which is a constituent material of the rough drawing wire, at a predetermined ratio, and the oxygen-free copper melt is supplied to the upward pulling continuous casting apparatus to produce a copper wire. Thus, it was confirmed that the softening temperature of the copper wire can be significantly lowered, the electrical conductivity can be increased, and no voids are generated in the conductor during welding, so that the connection reliability is greatly improved.

Claims (3)

In a method for producing a copper material directly from an oxygen-free copper melt using an upward pulling continuous casting apparatus,
Nb is added to the oxygen free copper melt stored in the molten metal storage means of the upward pulling continuous casting apparatus, and the ratio of Nb contained in the oxygen free copper melt is adjusted to 0.0006 to 0.06 wt%. A method for producing a copper material. In a method for producing a copper material directly from an oxygen-free copper melt using an upward pulling continuous casting apparatus,
At least one selected from Nb, Ti, Zr, Hf, V, Ta, Fe, B, Ca, Mg, or Misch metal is used as the oxygen-free copper molten metal stored in the molten metal storage means of the upward pulling continuous casting apparatus. A method for producing a copper material, comprising adding a seed metal or alloy and adjusting a ratio of each metal or alloy contained in the oxygen-free copper melt to 0.0006 to 0.06 wt%.   A copper material manufactured using the manufacturing method according to claim 1 or 2, wherein a semi-softening temperature is 115 ° C or lower.