JPS6167763A - Working method of high-melting point metallic materials - Google Patents

Abstract

PURPOSE:To manufacture a wire rod of the superior secondary working and of relatively large wire diameter by hammering or rolling a sintered body of high melting point metallic material, performing recrystallization on the way properly ad wire drawing. CONSTITUTION:A sintered body of a high welting point metallic material W and the like is hammered, rolled and wire drawn sequently. At the manufacture of a wire rod of more than 1mm in diameter, the crystallization treatment is performed at 50-60% reduction on the way of hammering and rolling so that the number of crystal grain per 1cm2 section of the sintered body may be more than 2,500. In the next wire drawing, the reduction is preferably >=25% and <=45% per a drawing. Thus, the wire rod of relatively large diameter, sufficient ductility, good bending which never occurs the folding in the secondary working such as drawing can be obtained with high yield.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for processing high-melting point metal materials, and more specifically, the present invention relates to a method for processing high-melting point metal materials, and more specifically, a method for processing high-melting point metal materials, which has a relatively large wire diameter and good bendability, and is capable of processing fine wire processing, straight processing, etc. The present invention relates to a method for processing a high-melting point metal material, which allows a high yield of wire rods that do not cause a single bend in a secondary processing step.

[Technical background of the invention and its problems]

Conventionally, when processing a high-melting point metal material, such as a tungsten material, into a relatively thick wire, specifically a wire with a wire diameter of 2 to 2.7, a method of rolling or rolling a tungsten sintered body has been applied. It had been. However, the method of obtaining a wire rod with a wire diameter of 2 to 2.7 ++ m only by rolling or rolling has problems in that the productivity is extremely low and the length of the wire rod obtained is limited.

Therefore, we decided to use a method that combines rolling or rolling with thin wire processing. In other words, after rolling the sintered body multiple times in a groove that makes the wire diameter thicker than the desired wire diameter, A method has been proposed in which a wire rod of a desired diameter is obtained by drawing the wire at a reduction in area.

In this method, the crystal grain size of the workpiece is adjusted during rolling or rolling, which is performed multiple times, to grow elongated and coarse crystal grains in the direction of the line axis, thereby imparting ductility to the workpiece. As the treatment, a so-called recrystallization treatment is performed in which the workpiece is heated to a temperature higher than the recrystallization temperature by directly applying electricity to the workpiece.

In addition, in the subsequent wire drawing process, the wire drawn from the die is once wound up into a roll, and then further transferred to so-called secondary processing processes, such as fine wire processing or straight line processing using a strainer, etc. to make it into a product. It is common that this is the case.

However, in the conventional method as described above, the bending workability of the wire obtained through rolling or rolling and wire drawing is poor, so the thin wire processing performed during or after winding into rolls as described above is difficult. Electrical bending of wire rods may occur during secondary processing steps such as wire processing and straight line processing, which may lead to a decrease in the yield of the final product.

[Purpose of the invention]

The present invention solves such conventional problems, and in manufacturing a wire rod with a wire diameter of 1 mm or more, preferably 2 to 2.7 mm,
The purpose of the present invention is to provide a method for processing high-melting point metals, which can produce wire rods with good bending workability and excellent secondary workability at a high yield.

[Summary of the invention]

In order to achieve the above object, the inventors of the present invention have conducted extensive research, and have found that "one fold" during conventional roll winding or secondary processing process is the area reduction rate per processing during wire drawing processing. In other words, conventional wire drawing processing is performed with an area reduction rate of 20% or less per process; In this case, since the processing energy does not propagate to the inside of the wire, only the surface of the wire is processed, and the inside of the wire is still brittle.Therefore, it is assumed that the wire does not have enough ductility to withstand secondary processing. be done.

In addition, the present inventors focused on the crystalline state after the recrystallization treatment performed during the rolling or rolling process, and found that the number of crystal grains per unit cross-sectional area after the recrystallization process is higher than the rolling or rolling process. We investigated the effect on the wire diameter and elongation of the wire rod finally obtained through wire drawing, and obtained the results shown in the figure.

In the figure, the elongation rate with respect to the wire diameter of the wire rod was measured by changing the number of crystal grains after recrystallization treatment.
T and ■ have crystal grain numbers of 1000 and 2000, respectively.
and 3000 pieces 101= are shown. As is clear from this figure, the larger the number of crystal grains, that is, the smaller the crystal grains, the greater the elongation rate of the finally obtained wire at a larger wire diameter. In other words, the peak of each curve has moved to the right in the figure. In the conventional technology, the number of crystal grains after recrystallization treatment is 1000 to 2000/
crl, it was revealed that the finally obtained wire did not have ductility due to this and the small area reduction rate during wire drawing.

Therefore, based on the above two findings, the present inventors carried out recrystallization treatment under conditions that increase the number of crystal grains as much as possible in the process of rolling or rolling the sintered body, and in addition, in the subsequent wire drawing process. In this paper, we discovered a processing method for obtaining a wire with high ductility by combining two processes of wire drawing with a large area reduction rate, and completed the present invention.

That is, the method for processing a high melting point metal of the present invention involves sequentially subjecting a sintered body of a high melting point metal material to rolling or rolling and wire drawing to produce a wire rod with a wire diameter of 1 inch or more. It is characterized by performing a recrystallization treatment so that the number of crystal grains per square centimeter of cross section of the sintered body becomes 2,500 or more during the punching process.

In the method of the present invention, a high melting point metal such as tungsten sintered body is first subjected to a rolling process several times at a predetermined area reduction rate, until the number of crystal grains after recrystallization reaches 2500. The recrystallization treatment of the sintered body is performed under conditions such that the roughness is preferably about 3000 (fllv'ttl).

These conditions mean the degree of processing of the sintered body, that is,
Recrystallization treatment may be performed when the area reduction rate reaches 50 to 60%.

Next, the sintered body, which has been turned into a bar material through the rolling process, is transferred to a wire drawing process, and the same wire drawing process is performed a plurality of times at a predetermined area reduction rate. The area reduction ratio is preferably 25 inches or more, more preferably 30 inches or more, in order to make the obtained wire exhibit sufficient ductility. By setting a large area reduction ratio in this way, processing energy is uniformly propagated to the inside of the wire.

However, if the area reduction rate is too large, problems such as cracks and bulges will begin to occur due to excessive accumulation of machining distortion, so it is desirable that the area be less than 45φ, and more preferably less than 40 inches.

After the above steps are completed, the wire rod is transferred to the secondary processing step as described above, but in the method of the present invention, both the number of grains in the rolling or rolling step and the area reduction rate in the wire drawing step are adjusted. Therefore, the obtained wire rod has sufficient ductility and good bending workability, so that there is no problem such as "folding" occurring in the secondary processing step.

[Embodiments of the invention]

As an example, a case will be described in which the method of the present invention is applied to a tungsten sintered body.

A tungsten sintered body having a rectangular cross section of 12 squares vertically and 12 squares horizontally was passed through a rolling process multiple times.

In each processing step, the sintered body or the processed bar is heated in a hydrogen furnace at 1300-1500°C before being inserted into the rolling mill.
Processing was performed after heating. In this step, when the sintered body had become a rod having a circular cross section with a diameter of 8 to 9 degrees, this rod was subjected to a recrystallization treatment at 2200 to 2400°C. The number of crystal grains after this recrystallization treatment is 300.
It was 0 pieces/crll. Thereafter, rolling was performed again to obtain a bar having a diameter of 4 mm and a circular cross section.

Next, this bar material was passed through a wire drawing process, and wire drawing processing was performed three times at a reduction rate of 30% per processing step, to finally obtain a wire rod with a diameter of 2.70.

Thereafter, this wire rod was transferred to secondary processing steps such as straight line processing and fine wire processing, but the wire rod did not break at all, and the final product could be obtained with a high manufacturing yield. On the other hand, in the conventional method, one fold occurs during roll winding in the wire drawing process, or one fold occurs in the secondary processing process as described above, so the manufacturing yield is lower than the method of the present invention. significantly decreased compared to

〔Effect of the invention〕

As is clear from the above explanation, according to the method of the present invention, the wire rod obtained through the rolling process and wire drawing process has good ductility, so secondary workability is improved and the product yield is improved. can be significantly increased, and its industrial value is great.

[Brief explanation of the drawing]

The figure shows the results of measuring the elongation rate with respect to the wire diameter of the wire by varying the number of crystal grains per unit cross-sectional area of the sintered body after recrystallization treatment. Q5 1. OL5 strain type (mmφ)

Claims (1)

[Scope of Claims] 1. When manufacturing a wire rod with a wire diameter of 1 mm or more by sequentially subjecting a sintered body of a high-melting point metal material to rolling or rolling and wire drawing, during the rolling or rolling process, A method for processing a high melting point metal material, which comprises performing a recrystallization treatment such that the number of crystal grains per square centimeter of cross section of the sintered body becomes 2,500 or more. 2. The area reduction rate in the wire drawing process is 25% per process.
The method for processing a high melting point metal material according to claim 1, which is as described above.