Tungsten alloy wire and metal products

Abstract

To provide a tungsten alloy wire with superior flex resistance.SOLUTION: A tungsten alloy wire 1 is used in an environment that receives at least one thermal impact of at least 1100°C. The tungsten alloy wire 1 contains rhenium at a content of 5 to 26 wt.% inclusive.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to tungsten alloy wires and metal products.

Background Art

[0002] Patent Document 1 discloses a tungsten wire having a tensile strength of 3900 MPa or more.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a tungsten alloy wire having excellent bend resistance and a metal product including the tungsten alloy wire.

Means for Solving the Problems

[0005] A tungsten alloy wire according to one aspect of the present invention is a tungsten alloy wire used in an environment where it is subjected to a thermal influence of 1100 °C or higher at least once, and contains rhenium in a content of 5 wt% or more and 26 wt% or less. [[ID=4�]]

[0006] A metal product according to one aspect of the present invention includes the tungsten alloy wire according to the above aspect.

Effects of the Invention

[0007] According to the present invention, it is possible to provide a tungsten alloy wire having excellent bend resistance and a metal product including the tungsten alloy wire.

Brief Description of the Drawings

[0008] [Figure 1]Figure 1 is a schematic perspective view of a tungsten alloy wire according to an embodiment. [Figure 2A] Figure 2A is a schematic perspective view of a rod comprising a tungsten alloy wire according to an embodiment. [Figure 2B] Figure 2B is a schematic perspective view of an electrode comprising a tungsten alloy wire according to an embodiment. [Figure 2C] Figure 2C is a schematic perspective view of a stranded wire comprising tungsten alloy wire according to an embodiment. [Figure 3] Figure 3 shows the bending resistance of a tungsten alloy wire according to an embodiment after it has been affected by heat. [Figure 4] Figure 4 shows an overview of the coiling test of tungsten alloy wire according to the embodiment. [Modes for carrying out the invention]

[0009] In the following, tungsten alloy wires and metal products according to embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below are all specific examples of the present invention. Therefore, the numerical values, shapes, materials, components, arrangement and connection configurations of components, steps, and the order of steps shown in the following embodiments are examples only and are not intended to limit the present invention. Accordingly, components in the following embodiments that are not described in an independent claim will be described as optional components.

[0010] Furthermore, each figure is a schematic diagram and not necessarily a strictly accurate representation. Therefore, for example, the scale may not necessarily match in each figure. Also, in each figure, substantially identical components are given the same reference numerals, and redundant explanations are omitted or simplified.

[0011] Furthermore, in this specification, terms describing the shape of elements such as cylinders or circles, as well as numerical ranges, do not represent only strict meanings, but also include substantially equivalent ranges, such as differences of a few percent.

[0012] (Embodiment) [composition] First, the tungsten alloy wire according to this embodiment will be described using Figure 1. Figure 1 is a schematic perspective view of the tungsten alloy wire 1 according to this embodiment.

[0013] As shown in Figure 1, the tungsten alloy wire 1 is stored wound on a reel 2. The reel 2 may also be referred to as a bobbin, reel, spool, or drum. The tungsten alloy wire 1 has a total length of, for example, 100m on the order of meters to 1km on the order of kilometers, but is not particularly limited.

[0014] The tungsten alloy wire 1 shown in Figure 1 is used in the manufacture of metal products. Figures 2A to 2C are schematic perspective views showing examples of metal products comprising the tungsten alloy wire 1 according to this embodiment.

[0015] The rod 11 shown in Figure 2A is an example of a metal product and comprises a tungsten alloy wire 1. Specifically, the rod 11 is a tungsten alloy wire 1 of a predetermined length. The length of the rod 11 is not particularly limited and can be set to an appropriate length depending on the application. The rod 11 can be used as part of or as an intermediate processed component of various metal products comprising the tungsten alloy wire 1, but its application is not particularly limited. The rod may also be referred to as a pin.

[0016] The electrode 12 shown in Figure 2B is an example of a metal product and comprises a tungsten alloy wire 1. Specifically, the electrode 12 is made by tapering the tip of a tungsten alloy wire 1 of a predetermined length. The tip shape of the electrode 12 is, for example, conical, but is not limited to this. The tip shape of the electrode 12 may be a rounded cone or frustocone, or a pyramidal or frustoconical shape. The electrode 12 is used, for example, in electrical discharge machining, but its applications are not particularly limited.

[0017] The twisted wire 13 shown in FIG. 2C is an example of a metal product and includes a plurality of tungsten alloy wires 1. Specifically, the twisted wire 13 is a twisted yarn manufactured by performing a twisting process on a plurality of tungsten alloy wires 1 having a predetermined length. Note that the twisted wire 13 may be a covering yarn including the tungsten alloy wire 1 as a core wire or a sheath wire. One of the core wire and the sheath wire may be a metal wire other than the tungsten alloy wire 1, or may be chemical fiber, natural fiber, regenerated fiber, etc. The twisted wire 13 may be further bundled and used as a rope or a string, etc., and the application is not particularly limited.

[0018] Note that the examples of metal products using the tungsten alloy wire 1 are not limited to those shown in FIGS. 2A to 2C. For example, the metal product may be a saw wire, a mesh, a catheter, a fiber product, etc. The metal product may include the tungsten alloy wire 1 and a member formed using a material other than metal (for example, resin).

[0019] The tungsten alloy wire 1 according to the present embodiment is used in an environment that receives at least one thermal influence of 1100 °C or higher. Specifically, the tungsten alloy wire 1 receives at least one thermal influence during processing for manufacturing a metal product or during use as a metal product. Specific examples of the thermal influence include, for example, when the tungsten alloy wire 1 is welded to another metal member such as iron, or when it is used as a discharge electrode, etc., but it is not particularly limited.

[0020] Even if the tungsten alloy wire 1 receives a thermal influence of 1100 °C or higher, it is resistant to bending. That is, the tungsten alloy wire 1 has excellent bend resistance. Even if the tungsten alloy wire 1 is bent at a predetermined curvature, breakage or surface peeling does not occur. Note that 1100 °C is an example of the temperature at which tungsten undergoes primary recrystallization.

[0021] Generally, tungsten has the property of being able to withstand high temperatures. However, tungsten has a problem in that its grain boundaries are weak, meaning that cracks are easily formed starting from the grain boundaries. Specifically, when subjected to thermal effects to the extent that the size of the crystal grains changes (specifically, above the temperature at which tungsten undergoes primary recrystallization (1100°C)), not only do the tungsten crystal grains become larger and the number of grain boundaries decreases, but oxygen also enters the grain boundaries. As the number of grain boundaries decreases, the amount of oxygen that enters the grain boundaries also increases relatively, so the strength of tungsten decreases. As a result, when stress such as folding or bending is applied to tungsten after thermal effects, cracks are more likely to form starting from the grain boundaries, and the bending resistance deteriorates.

[0022] In contrast, the tungsten alloy wire 1 according to this embodiment contains tungsten and rhenium (Re), and the tungsten and rhenium form a solid solution to form the alloy. The rhenium content in the tungsten alloy wire 1 is 5 wt% to 26 wt%.

[0023] In tungsten alloy wire 1, the rhenium content is 5 wt% or more, which allows the rhenium present within the crystal grains to absorb oxygen that would otherwise enter when subjected to thermal effects. This reduces the amount of oxygen present at the grain boundaries, making it less prone to cracking and suppressing the deterioration of bending resistance.

[0024] Furthermore, in tungsten alloy wire 1, a solid solution of rhenium and tungsten can be formed because the rhenium content is 26 wt% or less. If the rhenium content exceeds 26 wt%, a solid solution cannot be formed, and the strength of tungsten alloy wire 1 may decrease, potentially making it brittle.

[0025] [Bending resistance] Next, the bending resistance of the tungsten alloy wire 1 according to this embodiment will be explained using Figures 3 and 4.

[0026] Figure 3 shows the bending resistance of the tungsten alloy wire according to this embodiment after being affected by heat. Examples 1 to 8 shown in Figure 3 are tungsten alloy wires that differ in at least one of their wire diameter and composition. The wire diameter of the tungsten alloy wire 1 according to each embodiment is in the range of 0.02 mm to 1.00 mm. The rhenium content in the tungsten alloy wire 1 according to each embodiment is in the range of 5 wt% to 26 wt%. The tungsten content in the tungsten alloy wire 1 according to each embodiment is in the range of 74 wt% to 95 wt%.

[0027] Figure 3 also illustrates the bending resistance of tungsten wires related to Comparative Examples 1 to 7. Comparative Examples 1 to 3 are tungsten alloy wires containing rhenium. The rhenium content in the tungsten alloy wires related to Comparative Examples 1 to 3 is 1 wt% or 3 wt% or less. The wire diameter of the tungsten alloy wires related to Comparative Examples 1 to 3 is 0.10 mm or 0.50 mm. Comparative Examples 4 to 6 are tungsten wires containing potassium (potassium-doped tungsten wires). The potassium content in the potassium-doped tungsten wires related to Comparative Examples 4 to 6 is 0.007 wt%. The wire diameter of the potassium-doped tungsten wires related to Comparative Examples 4 to 6 is 0.04 mm, 0.10 mm, or 0.50 mm. Comparative Example 7 is a pure tungsten wire that does not contain any additives. Note that each example and comparative example contains trace amounts of unavoidable impurities that are necessary during manufacturing.

[0028] The inventors of this application performed heat treatment at predetermined temperatures on tungsten alloy wires according to Examples 1 to 8, and on tungsten alloy wires, potassium-doped tungsten wires, and pure tungsten wires according to Comparative Examples 1 to 7. Five samples were prepared for each example and comparative example, and each sample was heat-treated at different temperatures (1100°C, 1300°C, 1500°C, 1700°C, and 2000°C). The heat treatment time did not have any particular effect, but for example, it was about 1 minute.

[0029] After heat treatment, coiling tests were performed on each sample of each example and each comparative example. Figure 4 shows an overview of the coiling test of tungsten alloy wire 1 according to this embodiment.

[0030] In the coiling test, a tungsten alloy wire 1 was wound around a rod-shaped core material 20 with a circular cross-section and uniform diameter, and it was confirmed whether or not the tungsten alloy wire 1 fractured or its surface peeled off. The diameter R of the cross-section of the core material 20 used in the coiling test was set to be the same as the wire diameter φ of the tungsten alloy wire 1 being tested. That is, the smaller the wire diameter of the tungsten alloy wire 1, the smaller the radius of curvature (larger curvature) at which bending (coiling) occurs. For example, in the case of the tungsten alloy wire 1 with a wire diameter of 1.00 mm according to Example 1, a cylindrical core material 20 with a wire diameter of 1.00 mm was used. In the case of the tungsten alloy wire 1 with a wire diameter of 0.04 mm according to Example 7, a cylindrical core material 20 with a wire diameter of 0.04 mm was used. The same applies to the tungsten alloy wire, potassium-doped tungsten wire, and pure tungsten wire according to Comparative Examples 1 to 7.

[0031] In the tungsten alloy wires 1 according to Examples 1 to 8 in Figure 3, no fracture or surface delamination occurred at any temperature (indicated as "OK" in the figure). In other words, regardless of the wire diameter, as long as the rhenium content is in the range of 5 wt% to 26 wt%, a tungsten alloy wire 1 that is resistant to bending (excellent bending resistance) can be realized even when subjected to thermal effects of 1100°C or higher.

[0032] In contrast, as shown in Comparative Examples 1 to 3, when the rhenium content was 1 wt% or 3 wt%, fracture or surface delamination occurred in all cases except for Comparative Example 3, which was subjected to a heat effect of 1100°C (indicated as "NG" in the figures). In Comparative Example 3, since the wire diameter was thin at 0.10 mm, it is assumed that at low temperatures (1100°C), there was little oxygen incorporated into the grain boundaries, and fracture did not occur.

[0033] Furthermore, as shown in Comparative Examples 4 to 6, in the case of potassium-doped tungsten wire, fracture or surface delamination occurred in all cases except when the wire diameter was small and the heat treatment temperature was low (1100°C in Comparative Example 5, and 1100°C and 1300°C in Comparative Example 6). Note that, unlike rhenium, potassium is present at the grain boundaries and does not have the effect of incorporating oxygen.

[0034] As shown in Comparative Example 7, in the case of pure tungsten wire, oxygen due to thermal effects enters the grain boundaries, resulting in fracture or surface delamination.

[0035] [Effects, etc.] As described above, the tungsten alloy wire 1 according to this embodiment is a tungsten alloy wire used in an environment that is subjected to thermal effects of 1100°C or higher at least once, and contains 5 wt% or more rhenium. wt% It contains the following amounts:

[0036] As a result, by containing 5 wt% or more of rhenium, the tungsten alloy wire 1 can absorb oxygen that enters the grain boundaries when subjected to heat, thereby suppressing the occurrence of cracks originating from the grain boundaries. Therefore, even when subjected to heat, it is possible to realize a tungsten alloy wire 1 that is less prone to breakage and has excellent bending resistance. Furthermore, by having a rhenium content of 26 wt% or less, an alloy (solid solution) of rhenium and tungsten can be formed, thereby increasing the strength of the tungsten alloy wire 1.

[0037] Furthermore, the metal product according to this embodiment includes a tungsten alloy wire 1. For example, the metal product may be a rod 11, an electrode 12, or a stranded wire 13.

[0038] As a result, the tungsten alloy wire 1 is resistant to bending, even if it is subjected to thermal effects during the manufacturing or use of the metal product. Therefore, the deterioration of the quality of the metal product can be suppressed.

[0039] [Manufacturing method] The tungsten alloy wire 1 according to this embodiment can be manufactured, for example, by the following method.

[0040] First, tungsten powder and rhenium powder are mixed, then press-molded and sintered to form an ingot. By adjusting the mixing ratio of tungsten powder and rhenium powder, the rhenium content can be adjusted to between 5 wt% and 26 wt%.

[0041] Next, the tungsten ingot is subjected to a swaging process, which involves forging and compressing it from the outside to create a wire. After that, wire drawing is performed using wire drawing dies. Wire drawing is carried out by using multiple wire drawing dies with different hole diameters, in an order in which the hole diameters gradually decrease.

[0042] By appropriately adjusting the bore diameter of the wire drawing die, tungsten alloy wire 1 in the range of 0.02 mm to 1.00 mm, as shown in Figure 3, can be manufactured. Heating at a predetermined temperature may be performed during wire drawing. Furthermore, surface treatment such as electropolishing may be applied to the tungsten alloy wire 1 after drawing.

[0043] (others) Although the tungsten alloy wire and metal products according to the present invention have been described above based on the above embodiments, the present invention is not limited to the above embodiments.

[0044] For example, tungsten alloy wire may contain ruthenium (Ru) or cobalt (Co) instead of rhenium. For example, tungsten alloy wire may have a tungsten content of 99.8 wt% and a ruthenium content of 0.2 wt%, and may contain trace amounts of impurities. After heat treatment of the tungsten alloy wire, coiling tests were performed, and no deterioration in bending resistance was observed at any of the heat treatment temperatures of 1100°C, 1300°C, 1500°C, 1700°C, and 2000°C.

[0045] Furthermore, the present invention also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art could conceive, as well as forms realized by arbitrarily combining the components and functions of each embodiment without departing from the spirit of the present invention. [Explanation of symbols]

[0046] 1 Tungsten alloy wire 11 bars 12 electrodes 13 stranded wire

Claims

1. A tungsten alloy wire used in an environment that is subjected to heat effects of 1100°C or higher at least once, The wire diameter is less than 0.1 mm. It contains rhenium in an amount of 5 wt% to 26 wt%, with the remainder consisting of tungsten and trace impurities. Tungsten alloy wire.

2. A metal product comprising a tungsten alloy wire according to claim 1.

3. The aforementioned metal product is an electrode or stranded wire. The metal product according to claim 2.

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