JPS60197858A - Manufacture of metallic wire having high melting point - Google Patents

Abstract

PURPOSE:To inhibit defects such as surface cracking during electropolishing and to improve the yield of products by heat treating a wire rod at a prescribed temp. between drawing and electropolishing stages to make the work strain uniform. CONSTITUTION:A sintered body of tungsten (alloy) is swaged and drawn to form a wire rod of >=0.2mm.phi diameter. This wire rod is annealed by heat treatment at 900-1,000 deg.C to make the work strain present in the wire rod uniform. The wire rod is then electropolished to remove a black layer sticking to the surface of the wire rod.

Description

[Detailed Description of the Invention] [Technical Field of the Invention J] The present invention relates to a method for manufacturing a high-melting point metal wire, and more particularly, to a method for suppressing the occurrence of defects such as surface cranks during electrolytic polishing, thereby increasing the yield of non-defective wire rods. This invention relates to a method for manufacturing a metal wire with an increased melting point.

[Technical background of the invention and its problems]

A wire made of a high melting point metal, such as a tungsten (W) wire.

Tungsten-rhenium (W-Re) alloy wire, etc. h Generally, it is manufactured as follows.

First, a sintered body of a high-melting point metal produced using a known powder metallurgy method is hot rolled several times.

The structure is densified and the uniaxial crystals are stretched and arranged into fibers to form a wire rod with toughness.

The wire is then heat treated as necessary to remove internal distortion caused by the rolling process, and then passed through a number of dies with hole diameters that gradually change from large to small, either hot or warm, to form the wire. The wire is drawn to become even thinner. 1 usually in this process.

Since a graphite suspension is used as a lubricant, a black surface adhesion layer consisting of graphite and an oxide such as W is formed on the surface of the wire after the wire drawing process is completed.

Although Nire et al.'s wire rods are sometimes used in this state, they are sometimes further subjected to electrolytic polishing treatment to remove the surface adhesion layer, leaving one surface in a white, glossy state.

However, in this electrolytic polishing process, cracks, cracks, etc. often occur on the surface of the wire, which inevitably increases the defective rate of the product. In the case of a wire rod with a small diameter, the occurrence of this surface defect is relatively rare, but in the case of a relatively thick wire rod with a wire diameter of 6.2 uφ or more after wire drawing, the occurrence of this surface defect is relatively low. rate becomes extremely high.

[Object of the Invention] The present invention suppresses the occurrence of surface defects during the next electrolytic polishing of relatively thick wire rods with a wire diameter of 0.21Bφ or more after drawing, thereby increasing the yield of good wire rods. The purpose is to provide a method to increase

[Summary of the Invention] As a result of extensive research into the causes of surface defects during electrolytic polishing of thick wires, the present inventors have found that these surface defects occur during wire drawing due to the fact that the m material is a thick wire. It was discovered that this was caused by residual machining distortion inside the machine, resulting in an imbalance.

In order to eliminate this imbalance, we came up with the idea of heat treatment and annealing before electrolytic polishing and developed the method of the present invention.

Specifically, the method of the present invention is a method for manufacturing a high-melting point metal wire, in which a sintered slag of a high-melting point metal is subjected to rolling processing, then wire-drawn to form a wire rod, and then the wire rod is electrolytically polished. The method for producing high-melting point gold NhJ is characterized in that a heat treatment (t-) is performed to uniformize the processing strain existing in the wire between the wire drawing process and the electrolytic polishing process.

The high melting point metal here refers to alloys such as W, W-Re, and alloys such as molybdenum CM')*Mo-W alloy.

In the method of the present invention, first, a sintered body is manufactured from the above-mentioned metal by a commonly used powder metallurgy method. Next, this sintered body is passed through a number of rolling machines to be rolled, and then the wire diameter is reduced to form a round bar with a predetermined diameter. Heat treatment is performed according to the conditions to remove the distortion accumulated during the rolling process of both stages.

In the wire drawing process, the transferred wire is passed through multiple ties to gradually reduce its diameter. According to the sixth aspect of the present invention, the effect is significant when the wire diameter of the wire after drawing is 0.2 stroke φ or more, and this effect is remarkable up to about 3 uφ. Particularly, a wire diameter of 1-1.81 Bφ is very effective.

In line drawing processing, 1. A graphite suspension is applied to the wire to give it lubricity, and the wire is passed through a die. The wire rod pulled out from the die is subjected to heat treatment, and then subjected to the above-described treatment again and passed through the next stage die. By repeating this process multiple times, a wire rod having the desired wire diameter is finally obtained.

Next, electropolishing is performed to remove the black adhesion layer on the surface of the wire. Electrolytic polishing is usually carried out using a caustic soda solution as an electrolyte and using direct current or alternating current.

Note that the above-mentioned wire drawing process is performed continuously.

Further, efficiency is increased if the wire rod that has completed this wire drawing process is directly passed to the next electrolytic polishing process.

The method of the present invention is characterized in that a heat treatment is performed to uniformize the processing strain existing in the wire during the transition from the end of wire drawing to electrolytic polishing. Heat treatment.

Any heat treatment can be used as long as the surface and internal conditions of the wire are uniform, and annealing is performed by heating at a temperature of 900 to 1000°C, preferably 920 to 980°C. That is reasonable.

Specifically, for example, an annealing furnace is placed between the wire drawing process and the electrolytic polishing process, and the wire rod that comes out of the wire drawing process is allowed to run as it is through the annealing furnace, where it is annealed. It is introduced into the electrolytic polishing process.

A practical temperature range during annealing is 900 to 1000°C. If this temperature is too low, the unbalance between the residual strain on the surface and inside of the wire phase during wire drawing will not be effectively resolved, and if it is too high, losses due to oxidation and recrystallization embrittlement may occur. This may cause problems.

The atmosphere during annealing may be either an oxidizing atmosphere or a non-oxidizing atmosphere and is not particularly limited. There is little oxidation loss in a caustic line in a non-oxidizing atmosphere. It was. The annealing time is also not particularly limited.

A further example of the invention: W slag was produced using a powder metallurgy method. This slag was subjected to a rolling process to obtain a wire rod with a wire diameter of 2.5 nφ.

Next, this IvI! Trace @ to the 6-stage die and wire diameter 1
．． The wire rod had a diameter of 55. The surface was dotted. The obtained wire rod was passed through an annealing furnace with a length of about 50 scratches at 950°C in an air atmosphere at a running speed of about 10 m/min, and then electrolytically polished in a 251% caustic soda solution to a wire diameter of 1.5 φ. Obtained wire rod. When defects on the surface of the wire after electrolytic polishing were observed, no number of defects per 1 mm of wire length was observed.

For comparison, we electrolytically polished the wire directly after wire drawing under the same conditions as above without passing it through an annealing furnace, and observed defects on the # material surface, and found that MJ cranks occurred from half of the wire length to the entire subsequent length. .

(Effect of the invention〕

Claims (1)

[Scope of Claims] 1. A method for producing a high melting point metal wire, in which a sintered body of high melting point metal is subjected to rolling processing, then wire drawing is performed to obtain a wire rod, and then the wire rod is electrolytically polished. A method for producing a high-melting point metal wire, which comprises performing a heat treatment to uniformize processing distortion existing in the wire between the wire drawing process and the electrolytic polishing. 2. The method according to claim 1, wherein the high melting point metal wire is a tungsten wire or a tungsten alloy wire. 3. The method according to claim 1, wherein the wire diameter is 0.2111φ or more. 4. The method according to claim 1, wherein the heat treatment is performed at 900 to 1000°C.