Tungsten alloy wire and metal products

Abstract

The tungsten alloy wire (1) is a tungsten alloy wire that has been subjected to a heat treatment environment of at least 1100°C or higher. The tungsten alloy wire (1) contains rhenium at a content of 5 wt% or more and 26 wt% or less.

Description

[Technical Field]

[0001] This invention relates to a tungsten alloy wire and metal products. [Previous Technology]

[0002] Patent Document 1 discloses a tungsten wire with a tensile strength of 3900 MPa or higher. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-001660 [Summary of the Invention]

[0004] [The problem the invention aims to solve]

[0005] The object of this invention is to provide a tungsten alloy wire with excellent bending resistance and a metal article having the tungsten alloy wire. [Means for solving the problem]

[0006] The tungsten alloy wire of the present invention is used in an environment subjected to at least one heat treatment at 1100°C or higher, and contains rhenium in a content of 5 wt% or more and 26 wt% or less.

[0007] The metal article of the present invention comprises the tungsten alloy wire of the above-described form. [Effects of the Invention]

[0008] According to the present invention, a tungsten alloy wire with excellent bending resistance and a metal article having the tungsten alloy wire can be provided.

Implementation Method

[0010] [Form used to implement the invention]

[0011] Hereinafter, tungsten alloy wires and metal articles according to embodiments of the present invention will be described in detail using drawings. Furthermore, the embodiments described below are all specific examples illustrating the present invention. Therefore, the values, shapes, materials, constituent elements, configurations and connection methods of constituent elements, steps, and order of steps shown in the following embodiments are examples and are not intended to limit the scope of the present invention. Therefore, in the constituent elements of the following embodiments, constituent elements not described in the independent claims will be described using arbitrary constituent elements.

[0012] Furthermore, the diagrams in each series may not be strictly representational. Therefore, for example, the scales in each diagram may not be consistent. Moreover, substantially identical structures in each diagram may be marked with the same symbol, while repeated explanations may be omitted or simplified.

[0013] Furthermore, in this specification, the use of terms indicating the shape of elements such as cylinders or circles, as well as numerical ranges, is not merely a representation of a strict meaning, but rather means that they also include substantially equivalent ranges, such as differences of a few percent or so.

[0014] (Embodiment) [Structure] First, the tungsten alloy wire of this embodiment will be explained using FIG1. ​​FIG1 is a schematic perspective view of the tungsten alloy wire 1 of this embodiment.

[0015] As shown in Figure 1, the tungsten alloy wire 1 is wound onto a winding rack 2 for storage. The winding rack 2 may be called a bobbin, reel, spool, or drum. The tungsten alloy wire 1 has a total length ranging from approximately 100m in meters (m) to approximately 100km in kilometers (km), but is not particularly limited.

[0016] The tungsten alloy wire 1 shown in FIG1 is used in the manufacture of metal products. FIG2A-2C are schematic perspective views showing an example of a metal product having the tungsten alloy wire 1 of this embodiment.

[0017] The rod 11 shown in Figure 2A is an example of a metal article, which includes 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 formed to an appropriate length according to the application. The rod 11 is used as part of or as an intermediate processing component of various metal articles including the tungsten alloy wire 1, and its application is not particularly limited. In addition, the rod is also sometimes referred to as a pin.

[0018] The electrode 12 shown in Figure 2B is an example of a metal product, comprising a tungsten alloy wire 1. Specifically, the electrode 12 has a thinner front end portion of a predetermined length of tungsten alloy wire 1. The front end shape of the electrode 12 is, for example, a conical shape, but is not limited thereto. The front end shape of the electrode 12 may also be a conical shape with a rounded front end, a frustum-shaped cone, or a pyramidal or frustum-shaped cone, etc. The electrode 12 is used for, for example, electrical discharge machining, and its application is not particularly limited.

[0019] The stranded wire 13 shown in Figure 2C is an example of a metal product, comprising a plurality of tungsten alloy wires 1. Specifically, the stranded wire 13 is a stranded wire manufactured by stranding a plurality of tungsten alloy wires 1 of a predetermined length. Furthermore, the stranded wire 13 may also be a sheath wire having tungsten alloy wires 1 as the core or sheath. One of the core and sheath wires may be a metal wire other than tungsten alloy wire 1, or it may be a chemical fiber, natural fiber, recycled fiber, etc. The stranded wire 13 may also be further bundled and used in ropes or strips, etc., and its application is not particularly limited.

[0020] Furthermore, examples of metal products utilizing tungsten alloy wire 1 are not limited to those shown in Figures 2A to 2C. For example, the metal product may also be a saw wire, mesh, conduit, fiber product, etc. The metal product may also include a component formed by using tungsten alloy wire 1 and a material other than metal (e.g., resin).

[0021] The tungsten alloy wire 1 of this embodiment is used in an environment subjected to at least one heat treatment at 1100°C or above. Specifically, the tungsten alloy wire 1 is subjected to at least one heat treatment when it is used in the processing of manufacturing metal products or when it is used as a metal product. Specific examples of heat treatment include, for example, when the tungsten alloy wire 1 is welded to other metal components such as iron or when it is used as a discharge electrode, etc., and are not particularly limited.

[0022] The tungsten alloy wire 1 remains resistant to bending even when subjected to heat above 1100°C. That is, the tungsten alloy wire 1 has excellent bending resistance. Even when the tungsten alloy wire 1 is bent at a predetermined curvature, it will not break or peel off. Furthermore, 1100°C is an example of the temperature at which tungsten undergoes primary recrystallization.

[0023] Generally speaking, tungsten has the characteristic of high temperature resistance. However, tungsten has weak grain boundaries, meaning that cracks easily appear at the grain boundaries. Specifically, when subjected to thermal effects of changes in grain size (specifically, above the temperature at which tungsten undergoes primary recrystallization (1100°C)), not only do the tungsten grains become larger and the grain boundaries decrease, but oxygen also enters the grain boundaries. Because the grain boundaries decrease, the amount of oxygen entering the grain boundaries also increases relatively, thus weakening the strength of tungsten. As a result, after thermal effects, when stress such as bending or flexing is applied to tungsten, cracks easily appear at the grain boundaries, and the bending resistance deteriorates.

[0024] In this embodiment, the tungsten alloy wire 1 contains tungsten and rhenium (Re), which are alloyed by forming a solid solution. The rhenium content of the tungsten alloy wire 1 is 5 wt% or more and 26 wt% or less. Alternatively, the rhenium content of the tungsten alloy wire 1 may be 6 wt% or more, 7 wt% or more, 8 wt% or more, 9 wt% or more, 10 wt% or more, 12 wt% or more, 15 wt% or more, or 20 wt% or more. Furthermore, the rhenium content of the tungsten alloy wire 1 may be 25 wt% or less, 20 wt% or less, or 15 wt% or less, 12 wt% or less, 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, or 6 wt% or less.

[0025] The tungsten alloy wire 1 has a rhenium content of 5 wt% or more. The rhenium present in the grains can absorb oxygen that enters when affected by heat. In this way, since the amount of oxygen present at the grain boundaries is reduced, cracks are less likely to occur, and the deterioration of bending resistance can be suppressed.

[0026] Furthermore, the tungsten alloy wire 1 can form a solid solution of rhenium and tungsten when the rhenium content is below 26 wt%. When the rhenium content exceeds 26 wt%, a solid solution cannot be formed, and there is a risk that the strength of the tungsten alloy wire 1 will decrease and it will be prone to cracking.

[0027] [Bending resistance] Next, the bending resistance of the tungsten alloy wire 1 of this embodiment will be explained using Figures 3 and 4.

[0028] Figure 3 is a diagram showing the bending resistance of the tungsten alloy wire of this embodiment after being subjected to heat. Examples 1 to 8 shown in Figure 3 are tungsten alloy wires with at least one different wire diameter and composition. The wire diameter of the tungsten alloy wire 1 in each embodiment is in the range of 0.02 mm or more and 1.00 mm or less. Furthermore, the rhenium content of the tungsten alloy wire 1 in each embodiment is in the range of 5 wt% or more and 26 wt% or less. Also, the tungsten content of the tungsten alloy wire 1 in each embodiment is 74 wt% or more and 95 wt% or less.

[0029] Furthermore, Figure 3 also shows the bending resistance of the tungsten wires of Comparative Examples 1-7. Comparative Examples 1-3 are tungsten alloy wires containing rhenium. The rhenium content of the tungsten alloy wires of Comparative Examples 1-3 is 1 wt% or less, or 3 wt% or less. The wire diameter of the tungsten alloy wires of Comparative Examples 1-3 is 0.10 mm or 0.50 mm. Comparative Examples 4-6 are tungsten wires containing potassium (potassium-doped tungsten wires). The potassium content of the potassium-doped tungsten wires of Comparative Examples 4-6 is 0.007 wt%. The wire diameter of the potassium-doped tungsten wires of Comparative Examples 4-6 is 0.04 mm, 0.10 mm, or 0.50 mm. Comparative Example 7 is a pure tungsten wire without any additives. In addition, each embodiment and each comparative example also contains trace amounts of unavoidable impurities that are unavoidable in manufacturing.

[0030] The inventors of this case heat-treated the tungsten alloy wires of Examples 1-8, and the tungsten alloy wires, potassium-doped tungsten wires, and pure tungsten wires of Comparative Examples 1-7 at predetermined temperatures. For each example and each comparative example, five samples were prepared, and each sample was heat-treated at different temperatures (1100°C, 1300°C, 1500°C, 1700°C, and 2000°C). The heat treatment time, for example, was approximately 1 minute and did not have a significant impact.

[0031] After heat treatment, winding tests were conducted on each sample of each embodiment and each comparative example. Figure 4 is a diagram showing a summary of the winding test of the tungsten alloy wire 1 of this embodiment.

[0032] In the winding test, a tungsten alloy wire 1 was wound around a rod-shaped core material 20 with a circular cross-section and uniform diameter to confirm whether the tungsten alloy wire 1 broke or peeled off. The diameter R of the cross-section of the core material 20 used in the winding test was the same as the wire diameter φ of the tungsten alloy wire 1. That is, the smaller the wire diameter of the tungsten alloy wire 1, the smaller the radius of curvature (the larger the curvature) it was bent (wound). For example, when using the tungsten alloy wire 1 with a wire diameter of 1.00 mm in Example 1, a cylindrical core material 20 with a wire diameter of 1.00 mm was used. When using the tungsten alloy wire 1 with a wire diameter of 0.04 mm in Example 7, a cylindrical core material 20 with a wire diameter of 0.04 mm was used. The same applies to the tungsten alloy wires, potassium-doped tungsten wires, and pure tungsten wires in Comparative Examples 1 to 7.

[0033] The tungsten alloy wire 1 of Examples 1 to 8 in Figure 3 did not break or peel off at any temperature (indicated by "OK" in the figure). That is, regardless of the wire diameter, a tungsten alloy wire 1 that is resistant to bending (excellent bending resistance) can be achieved even when subjected to heat effects above 1100°C, provided that the rhenium content is between 5 wt% and 26 wt%.

[0034] In contrast, as shown in Comparative Examples 1 to 3, when the rhenium content was 1 wt% or 3 wt%, except for the case of Comparative Example 3 which was subjected to thermal effects at 1100°C, fracture or surface peeling occurred (indicated by "NG" in the figure). In Comparative Example 3, since the wire diameter was 0.10 mm and it was thin, it was assumed that at the low temperature (1100°C), the amount of oxygen absorbed to the grain boundaries was small and therefore fracture would not occur.

[0035] Furthermore, as shown in Comparative Examples 4 to 6, when the tungsten wire was doped with potassium, fracture or surface peeling occurred except in cases where 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 Examples 6). In addition, potassium, unlike rhenium, exists at grain boundaries and does not have the effect of absorbing oxygen.

[0036] As shown in Comparative Example 7, when the wire is pure tungsten, oxygen enters the grain boundaries due to the influence of heat, resulting in fracture or surface peeling.

[0037] [Effects, etc.] As described above, the tungsten alloy wire 1 of this embodiment is used in an environment subjected to heat effects of 1100°C or higher at least once, and contains rhenium with a content of 5 wt% or more and 26 wt% or less.

[0038] Therefore, the tungsten alloy wire 1 contains more than 5 wt% rhenium. Rhenium can absorb oxygen that enters the grain boundaries when affected by heat, thereby suppressing the occurrence of cracks originating from the grain boundaries. Therefore, even when affected by heat, it is not easy for the wire to break, thus achieving tungsten alloy wire 1 with excellent bending resistance. Furthermore, since the rhenium content is less than 26 wt%, an alloy (solid solution) of rhenium and tungsten can be formed, thereby improving the strength of tungsten alloy wire 1.

[0039] Furthermore, the metal article of this embodiment includes a tungsten alloy wire 1. For example, the metal article is a rod 11, an electrode 12, or a stranded wire 13.

[0040] Therefore, even when metal products are manufactured or used and subjected to heat, the tungsten alloy wire 1 remains resistant to bending. Thus, the degradation of the quality of metal products can be suppressed.

[0041] [Manufacturing Method] The tungsten alloy wire 1 of this embodiment can be manufactured by the following method.

[0042] First, tungsten powder and rhenium powder are mixed, pressed into shape, and then sintered to form an ingot. By adjusting the mixing ratio of tungsten powder and rhenium powder, the rhenium content can be adjusted to be more than 5 wt% and less than 26 wt%.

[0043] Next, the tungsten ingot is subjected to a forging process involving compression and extension from the surrounding area to form a wire. After that, wire drawing is performed using a drawing die. Wire drawing is performed by using a plurality of drawing dies with different apertures in order of decreasing aperture.

[0044] By appropriately adjusting the aperture of the 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. Furthermore, heating to a predetermined temperature can be performed during wire drawing. Also, surface treatments such as electrolytic polishing can be applied to the drawn tungsten alloy wire 1.

[0045] (Others) The present invention has been described above in accordance with the above embodiments, but the present invention is not limited to the above embodiments.

[0046] For example, the tungsten alloy wire may also contain ruthenium (Ru) or cobalt (Co) to replace rhenium. For example, the tungsten alloy wire may contain 99.8 wt% tungsten, 0.2 wt% ruthenium, and trace amounts of impurities. After heat treatment, a winding test was conducted on the tungsten alloy wire. As a result, no deterioration in bending resistance was observed regardless of the heat treatment temperature of 1100°C, 1300°C, 1500°C, 1700°C, or 2000°C.

[0047] In addition, the present invention also includes forms obtained by implementing various modifications conceived by the operator in each embodiment, or forms achieved by arbitrarily combining the constituent elements and functions of each embodiment without departing from the purpose of the present invention. [Simplified Explanation of the Diagram]

[0009] Figure 1 is a schematic perspective view of the tungsten alloy wire of the embodiment. Figure 2A is a schematic perspective view of a rod of the tungsten alloy wire of the embodiment. Figure 2B is a schematic perspective view of an electrode of the tungsten alloy wire of the embodiment. Figure 2C is a schematic perspective view of a stranded wire of the tungsten alloy wire of the embodiment. Figure 3 is a diagram showing the bending resistance of the tungsten alloy wire of the embodiment after being subjected to heat. Figure 4 is a diagram showing the outline of the winding test of the tungsten alloy wire of the embodiment.

Claims

1. A tungsten alloy wire having a diameter of 0.02 mm or more and 1.00 mm or less, and containing rhenium in a content of 12 wt% or more and 26 wt% or less.

2. A metal article comprising the tungsten alloy wire as claimed in claim 1.

3. Metal articles as claimed in item 2, including rods, electrodes or strands.

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