JPS61110755A - Molybdenum wire rod and its manufacture - Google Patents

Abstract

PURPOSE:To obtain the Mo wire rod having desired bending strength, by specifying the reduction in area after heat treatment, in manufacturing the wire rod from an ingot which is made by subjecting Mo powder to press forming and sintering. CONSTITUTION:The Mo powder is subjected to press forming and sintering. The ingot is heat-treated while being rolled and forged to be recrystallized, which is drawn at >=99.4% reduction in area into the Mo wire rod. At this time, the density of fibers is desirably 500 pieces/mm<2>. In this method, the frequency of bending and the density of fibers are improved with the increase of the draft. In this way, the Mo wire rod having high bending strength and suitable for printing wires for a printer or the like can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a molybdenum wire and a method for manufacturing the same, and more particularly, to a molybdenum wire effective as a printing wire for a printer and a method for manufacturing the same.

(Prior Art) Generally, molybdenum wire rods are made by pressing powdered molybdenum, forming it, and then sintering it into an ingot.

While rolling or rolling the pickled ingot, it is subjected to intermediate heat treatment once or twice or more during the process.

Molybdenum wire rods of the required dimensions are manufactured by drawing wires while heating with gas or the like.

(Problems to be Solved by the Invention) When a molybdenum wire rod of 0.2φ to 0.4φ manufactured by the above-described method was mounted on a dot printer as a printing wire for a printer and tested, many breakages occurred and the wire could not be used sufficiently. It was unbearable.

However, as a printing wire for a printer, it must have enough bending strength to withstand five or more tests.

It is presumed that this is because conventional molybdenum wire rods have low bending strength.

More details below (Means for solving the problem) This invention is based on the fact that when manufacturing molybdenum wire rods, the cross-section reduction rate (workability) after heat treatment is related to the bending strength, and the improvement of workability is related to the fiber content. It was discovered that a method for producing a molybdenum wire rod with a cross-section reduction rate of 99.4% or more after heat treatment and a fiber degree of s o o '42
The above molybdenum wire material makes it possible to obtain a molybdenum wire material having a desired bending strength.

(Example) After changing the wire diameter of each wire (raw material) and recrystallizing it by heat treatment, as shown in Table 1, the final (product) wire diameter was 300 μm and the area reduction rate (processing degree) was 0 to 99. Sixteen types of material wire rods up to 96% were prepared, and their bending times and fiber content were measured. The bending strength (number of times) is determined by fixing the molybdenum wire 1 to a jig 2 with a 0.5R chamfer and repeatedly bending it 90 degrees left and right, as shown in Figure 1. The bending strength was determined based on the following. The number of bends is 1.
The average number of bends for 000 sample wires was calculated and fractions were rounded down.

34.8 37 057.3
46 071.0 56
182.1 91 ]89
・3 117 293.8
154 296.3 200
397.6 250 498.7
333 499.4 499
599.6 588 69
9.7 665 799.8
800 899.9 1,000
999.96 2,000 15
Also. To determine the fiber content, the longitudinal section of the wire is cut parallel to the center of the diameter, and then polished to a mirror finish by soaking it in an etching solution containing 10P of NaOH and 1OS of potassium cyanide (red blood salt) dissolved in 100cc of pure water for 15 seconds. The etched material was magnified 800 times using a metallurgical optical microscope, and the number of fibers aligned in the axial direction of the wire was measured within a certain width perpendicular to the axial direction, and the length was 1 mm (width of the length of 1 mttt). I calculated how many books were inside.

Figure 2 shows the machining rate (section reduction rate) based on this test result.
A diagram showing the relationship between the number of bends, the number of bends, and the degree of fiber.
It can be seen that as the processing rate increases, the number of bends and the fiber content also improve.

Therefore, the number of bends required for printing wire for printer is 5.
In order to satisfy the requirements above, the cross-sectional reduction rate (processing degree) after heat treatment must be 99.4% or more, and the fiber content must be so
K should be set so that EE/,,2 or more.

(Effects of the Invention) According to the present invention, it is possible to obtain a molybdenum wire rod with high bending strength, so it becomes possible to use the molybdenum wire rod for printing wires for wire dot printers that require high bending strength. It has the following effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a bending testing machine for molybdenum wire according to the present invention, and FIG. 2 is a diagram showing the relationship between the processing rate (reduction in area), the number of bends, and the fiber degree of the molybdenum wire according to the present invention.

Claims (1)

[Claims] 1) After press-molding molybdenum powder, sintering it into an ingot, recrystallizing it by heat-treating the ingot while rolling or rolling it, and then drawing it into a wire to produce a molybdenum wire rod. A method for producing a molybdenum wire, characterized in that the cross-section reduction rate (processing rate) after heat treatment is 99.4% or more. 2) Molybdenum wire with a fiber density of 500 lines/mm or more.