TUFFALO ALLOY WIRE AND METAL PRODUCTS

Abstract

A tungsten alloy wire (1) is to be used in an environment in which the tungsten alloy wire is subjected at least once to a thermal effect at a temperature of at least 1100 degrees Celsius. The tungsten alloy wire (1) comprises rhenium with a content of at least 5 wt.% and at most 26 wt.%.

Description

[Technical field]

[0001] The present invention relates to a tungsten alloy wire and metal products. [State of the art]

[0002] Patent Document (PTL) 1 discloses a tungsten wire having a tensile strength of at least 3900 MPa. [Document List][Patent Documents]

[0003] [PTL 1] Japanese unexamined patent application with publication number 2022-001660 [Summary of the invention][Technical problem]

[0004] An object of the present invention is to provide a tungsten alloy wire having excellent bending resistance and metal products comprising the tungsten alloy wire. [Solution to the problem]

[0005] According to one aspect of the present invention, a tungsten alloy wire is to be used in an environment in which the tungsten alloy wire is subjected to a thermal effect at a temperature of at least 1100 degrees Celsius at least once, and the tungsten alloy wire comprises rhenium in a content of at least 5 wt% and at most 26 wt%.

[0006] According to another aspect of the present invention, a metal product comprises the tungsten alloy wire described above. [Advantageous effects of the invention]

[0007] According to the present invention, a tungsten alloy wire having excellent bending resistance and metal products comprising the tungsten alloy wire can be provided. [Brief description of the drawings] [ Fig. 1] Fig. 1 is a schematic perspective view of a tungsten alloy wire according to an embodiment. [ Fig. 2A] Fig. 2A is a schematic perspective view of a rod including the tungsten alloy wire according to the embodiment. [ Fig. 2B] Fig. 2B is a schematic perspective view of an electrode including the tungsten alloy wire according to the embodiment. [ Fig. 2C] Fig. 2C is a schematic perspective view of a twisted wire including the tungsten alloy wire according to the embodiment. [ Fig. 3] Fig. 3 is a table showing the bending strengths of tungsten alloy wires according to the embodiment after being subjected to a thermal effect. [ Fig. 4] Fig. 4 is a diagram showing an overview of a winding test of the tungsten alloy wire according to the embodiment. [Description of embodiments]

[0008] Hereinafter, a tungsten wire and a metal mesh according to embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that each of the embodiments described below shows a specific example of the present invention. Therefore, the numerical values, shapes, materials, structural components, the arrangement and connection of the structural components, steps, the processing order of the steps, etc., given in the embodiments described below are merely examples and therefore do not limit the present invention. Of the structural components in the embodiments described below, those not recited in the independent claims are described as optional structural components.

[0009] Furthermore, each diagram is a schematic diagram and not necessarily accurately depicted. Accordingly, for example, scale dimensions, etc., are not necessarily accurately depicted. In each diagram, substantially the same structural components are assigned the same reference numerals, and redundant descriptions are omitted or simplified.

[0010] In addition, a term representing a component shape, such as "cylindrical" or "circular," and a numerical range are used in this specification. Such terms and such a range do not only represent the strict meaning of the term or range, but imply that essentially the same range, e.g., even a range encompassing a small difference of a few percent, is encompassed by the term or range. (Embodiment)[Structure]

[0011] First, a tungsten alloy wire according to the present embodiment will be described with reference to Fig. 1. The Fig. 1 is a schematic perspective view of the tungsten alloy wire 1 according to the present embodiment.

[0012] As it is in the Fig. As shown in Figure 1, the tungsten alloy wire 1 is wound and supported around a winding frame 2. The winding frame 2 may in some cases be referred to as a bobbin, reel, spool, drum, or the like. The tungsten alloy wire 1 has, for example, but is not specifically limited to, a total length in the range of the order of meters (m), such as approximately 100 m, to the order of kilometers (km).

[0013] The tungsten alloy wire 1 used in the Fig. 1 is used in the manufacture of metal products. Fig. 2A to Fig. 2C are each a schematic perspective view showing an example of a metal product including a tungsten alloy wire 1 according to the present embodiment.

[0014] The staff 11, which is in the Fig. 2A is an example of the metal product and includes the tungsten alloy wire 1. Specifically, the rod 11 is a tungsten alloy wire 1 having a predetermined length. The length of the rod 11 is not limited to a specific length and can be manufactured to have a length suitable for the application of the rod 11. The rod 11 is used as sections of various metal products including the tungsten alloy wire 1 or intermediate workpieces of the metal products. However, the application of the rod 11 is not limited to a specific application. It should be noted that the rod may be referred to as a pin.

[0015] The electrode 12, which is in the Fig. 2B is an example of the metal product and includes the tungsten alloy wire 1. Specifically, the electrode 12 is a tungsten alloy wire 1 having a predetermined length, and the tip portion of the tungsten alloy wire 1 is processed to be thin. The shape of the tip of the electrode 12 is, for example, but not limited to, a cone shape. The shape of the tip of the electrode 12 may be a cone shape with a round tip, or a truncated cone shape, a pyramid or truncated pyramid shape, or the like. The electrode 12 is used, for example, in electric discharge machining. However, the application of the electrode 12 is not limited to a specific application.

[0016] The twisted wire 13, which is in the Fig. 2C is an example of the metal product and includes a plurality of tungsten alloy wires 1. Specifically, the twisted wire 13 is a twine produced by twisting and twisting the plurality of tungsten alloy wires 1 having a predetermined length. It should be noted that the twisted wire 13 may be a covered thread including the tungsten alloy wire 1 as a core thread or a sheath thread. One of the core thread and the sheath thread may be a metal wire other than the tungsten alloy wire 1, or may be a chemical fiber, a natural fiber, a recycled fiber, or the like. Furthermore, the twisted wires 13 can be bundled for use as a rope, a cord, or the like. The application of the twisted wire 13 is not limited to a specific application.

[0017] It should be noted that the examples of the metal products comprising the tungsten alloy wire 1 are not limited to those described in Fig. 2A to Fig. 2C. For example, the metal products may be a saw wire, a mesh, a catheter, a fiber product, and the like. The metal products may include the tungsten alloy wire 1 and a member formed of a material other than a metal (e.g., a resin).

[0018] The tungsten alloy wire 1 according to the present embodiment is used in an environment in which the tungsten alloy wire 1 is subjected to a thermal effect at a temperature of at least 1100 degrees Celsius. Specifically, the tungsten alloy wire 1 is subjected to the thermal effect at least once during processing for manufacturing the metal product or when the tungsten alloy wire 1 is used as the metal product. A specific example of the thermal effect is, for example, but not specifically limited to, the case where the tungsten alloy wire 1 is welded to another metal member such as iron, or the case where the tungsten alloy wire 1 is used as a discharge electrode.

[0019] Even after being subjected to thermal treatment at a temperature of at least 1100 degrees Celsius, the tungsten alloy wire 1 exhibits excellent bending resistance. Even if the tungsten alloy wire 1 is bent to a predetermined curvature, fracture, surface delamination, or the like will not occur in the tungsten alloy wire 1. It should be noted that 1100 degrees Celsius is an example of a temperature at which tungsten undergoes primary recrystallization.

[0020] In general, tungsten has the property of withstanding high temperatures. However, tungsten has a problem in that its grain boundaries are brittle, meaning that cracks are likely to occur originating at the grain boundary. In particular, when tungsten is subjected to a thermal effect to the extent that grain sizes change (especially at least at a temperature at which tungsten undergoes primary recrystallization (1100 degrees Celsius)), tungsten grains grow, so grain boundaries are diminished, and in addition, oxygen penetrates into the grain boundaries. As the grain boundaries are diminished, the amount of oxygen that penetrates the grain boundaries increases relatively, which reduces the strength of tungsten.As a result, when folding, bending, or the like builds up stress in tungsten after the thermal effect, cracking is likely to occur originating at its grain boundary, causing deterioration of bending resistance.

[0021] In contrast, the tungsten alloy wire 1 according to the present embodiment contains tungsten and rhenium (Re), and tungsten and rhenium are alloyed to form a solid solution. The rhenium content of the tungsten alloy wire 1 is, for example, at least 5 wt% and at most 26 wt%. Alternatively, the rhenium content of the tungsten alloy wire 1 may be at least 6 wt%, at least 7 wt%, at least 8 wt%, at least 9 wt%, at least 10 wt%, at least 12 wt%, at least 15 wt%, or at least 20 wt%. Furthermore, the rhenium content of the tungsten alloy wire 1 may be at most 25 wt%, at most 20 wt%, at most 15 wt%, at most 12 wt%, at most 10 wt%, at most 9 wt%, at most 8 wt%, at most 7 wt%, or at most 6 wt%.

[0022] In the tungsten alloy wire 1, when the rhenium content is at least 5 wt%, rhenium present in the grains can capture the oxygen that penetrates when the tungsten alloy wire 1 undergoes the thermal effect. Thus, the amount of oxygen present in the grain boundaries can be reduced, making cracking unlikely and limiting the deterioration of bending strength.

[0023] Furthermore, in the tungsten alloy wire 1, when the rhenium content is 26 wt% or less, a solid solution of rhenium and tungsten may be formed. A rhenium content exceeding 26 wt% may not form a solid solution, and the strength of the tungsten alloy wire 1 may decrease, causing it to become brittle. [Bending resistance]

[0024] Next, the bending resistance of the tungsten alloy wire 1 according to the present embodiment will be described with reference to Fig. 3 and Fig. 4 described.

[0025] The Fig. Figure 3 is a table showing the bending strengths of tungsten alloy wires according to the present embodiment after being subjected to the thermal effect. Fig. Working examples 1 to 8 shown in Figure 3 are tungsten alloy wires that differ in at least one of diameter and composition. The diameters of tungsten alloy wires 1 according to the working examples are within the range of at least 0.02 mm and at most 1.00 mm. The rhenium contents of the tungsten alloy wires 1 according to the working examples are within the range of at least 5 wt% and at most 26 wt%. The tungsten contents of the tungsten alloy wires 1 according to the working examples are at least 74 wt% and at most 95 wt%.

[0026] The Fig. Figure 3 also shows the bending strengths of tungsten wires according to Comparative Examples 1 to 7. Comparative Examples 1 to 3 are tungsten alloy wires containing rhenium. The rhenium contents of the tungsten alloy wires according to Comparative Examples 1 to 3 are 1 wt% or at most 3 wt%. The diameters of the tungsten alloy wires according to Comparative Examples 1 to 3 are 0.10 mm or 0.50 mm. Comparative Examples 4 to 6 are tungsten wires containing potassium (potassium-doped tungsten wires). The potassium contents of the potassium-doped tungsten wires according to Comparative Examples 4 to 6 are 0.007 wt%. The diameters of the potassium-doped tungsten wires according to Comparative Examples 4 to 6 are 0.04 mm, 0.10 mm, or 0.50 mm. Comparative example 7 is a pure tungsten wire that contains no additives.It should be noted that each of the working examples and comparative examples contains trace amounts of unavoidable impurities that are inevitably mixed in during manufacture.

[0027] The present inventors subjected the tungsten alloy wires according to Working Examples 1 to 8 and the tungsten alloy wires, potassium-doped tungsten wires, and pure tungsten wires according to Comparative Examples 1 to 7 to heat treatment at predetermined temperatures. Five samples were prepared for each of the Working Examples and Comparative Examples, and the samples were subjected to heat treatment at different temperatures (1100 degrees Celsius, 1300 degrees Celsius, 1500 degrees Celsius, 1700 degrees Celsius, and 2000 degrees Celsius). The heat treatment time has no particular effect. For example, the heat treatment time is approximately one minute.

[0028] After heat treatment, the samples in the working examples and comparative examples were subjected to a winding test. Fig. 4 is a diagram showing an overview of the winding test of the tungsten alloy wire 1 according to the present embodiment.

[0029] In the winding test, the tungsten alloy wire 1 was wound around a core material 20 that was rod-shaped, had a circular cross-sectional shape, and had a uniform diameter, and it was checked whether any breakage or surface delamination occurred in the tungsten alloy wire 1. The diameter R of a cross-section of the core material 20 used in the winding test was set according to the diameter φ of the tungsten alloy wire 1 to be tested. That is, the winding test is designed so that bending (winding) is performed with a smaller radius of curvature (a larger curvature) for the tungsten alloy wire 1 with a smaller diameter. For example, in the case of the tungsten alloy wire 1 according to Working Example 1 having a diameter of 1.00 mm, a core material 20 having a columnar shape and a diameter of 1.00 mm was used.In the case of the tungsten alloy wire 1 according to Working Example 7, which has a diameter of 0.04 mm, a core material 20 having a columnar shape and a diameter of 0.04 mm was used. This applies to the tungsten alloy wires, the potassium-doped tungsten wires, and the pure tungsten wire according to Comparative Examples 1 to 7.

[0030] For the tungsten alloy wires 1 according to the working examples 1 to 8 in the Fig. 3, neither fracture nor surface delamination occurred at any of the temperatures (referred to as "OK" in the table). This means that within the range where the rhenium content was at least 5 wt% and at most 26 wt%, tungsten alloy wires 1 can be produced that are bend-resistant (exhibit excellent bending resistance) even after being subjected to the thermal effect at a temperature of at least 1100 degrees Celsius, regardless of their diameters.

[0031] In contrast, Comparative Examples 1 to 3 showed that fracture or surface delamination occurred in all tungsten alloy wires with rhenium contents of 1 wt% or 3 wt%, except for the tungsten alloy wire according to Comparative Example 3, which was subjected to the thermal effect at 1100 degrees Celsius. In Comparative Example 3, the diameter was small, 0.10 mm. Therefore, it is assumed that at the low temperature (1100 degrees Celsius), the amount of oxygen included in grain boundaries was small, which did not cause fracture.

[0032] Furthermore, Comparative Examples 4 to 6 showed that fracture or surface delamination occurred in all potassium-doped tungsten wires, except for the potassium-doped tungsten wires with small diameters and subjected to heat treatment at low temperatures (1100 degrees Celsius in Comparative Example 5 and 1100 degrees Celsius and 1300 degrees Celsius in Comparative Example 6). It should be noted that, unlike rhenium, potassium is present at grain boundaries and does not exhibit an oxygen-trapping effect.

[0033] Comparative Example 7 showed that fracture or surface delamination occurred in the pure tungsten wire because the thermal effect causes oxygen to penetrate into grain boundaries. [Effects, etc.]

[0034] As described above, the tungsten alloy wire 1 according to the present embodiment is to be used in an environment in which the tungsten alloy wire is subjected to a thermal effect at a temperature of at least 1100 degrees Celsius at least once, and the tungsten alloy wire includes rhenium in a content of at least 5 wt% and at most 26 wt%.

[0035] With this structure of the tungsten alloy wire 1, when at least 5 wt% of rhenium is contained, rhenium can capture oxygen that penetrates grain boundaries when the tungsten alloy wire 1 is subjected to the thermal effect, and thus the occurrence of cracking originating from a grain boundary can be restricted. Therefore, even after the tungsten alloy wire 1 is subjected to the thermal effect, breakage or the like is unlikely to occur in the tungsten alloy wire 1, and thus a tungsten alloy wire 1 having excellent bending resistance can be manufactured. Furthermore, when the rhenium content is at most 26 wt%, the alloy (solid solution) of rhenium and tungsten can be formed, and thus the strength of the tungsten alloy wire 1 can be increased.

[0036] The metal product according to the present embodiment includes the tungsten alloy wire 1. For example, the metal product is a rod 11, an electrode 12, or a twisted wire 13.

[0037] With this structure, the tungsten alloy wire 1 is resistant to bending even after being subjected to the thermal effect during the manufacture or use of the metal product. Accordingly, deterioration of the quality of the metal product can be prevented. [Manufacturing process]

[0038] The tungsten alloy wire 1 according to the present embodiment can be manufactured, for example, by the following method.

[0039] First, tungsten powder and rhenium powder are mixed together and subjected to compression molding and sintering to form an ingot. By adjusting the mixing ratio between the tungsten powder and rhenium powder, the rhenium content can be adjusted to a minimum of 5 wt% and a maximum of 26 wt%.

[0040] Next, a tungsten ingot formed into the block is formed into a wire shape by performing a die forging process in which the tungsten ingot is forged and compressed all around to lengthen it. Then, drawing (wire drawing) is performed using wire drawing dies (wire drawing dies). The drawing is performed using a plurality of wire drawing dies with different hole diameters in descending order of hole diameter.

[0041] By appropriately adjusting the hole diameters of the wire drawing dies, tungsten alloy wires 1 with diameters within the range of 0.02 mm to 1.00 mm can be produced, as described in the Fig. 3. It should be noted that the drawing may include heating at a predetermined temperature. Furthermore, after drawing, the tungsten alloy wire 1 may be subjected to a surface treatment, such as electrolytic polishing. (Miscellaneous)

[0042] Although the tungsten alloy wire and metal products according to the present invention have been described so far based on the above-described embodiments, the present invention is not limited to the above-described embodiments.

[0043] For example, the tungsten alloy wire may contain ruthenium (Ru) or cobalt (Co) instead of rhenium. For example, the 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. The tungsten alloy wire was subjected to heat treatment and then a coiling test. As a result, no deterioration in the bending strength of the tungsten alloy wire was observed in any of the cases where the heat treatment was carried out at temperatures of 1100 degrees Celsius, 1300 degrees Celsius, 1500 degrees Celsius, 1700 degrees Celsius, and 2000 degrees Celsius.

[0044] It should be noted that the present invention also includes other forms in which various modifications apparent to a person skilled in the art are applied to the embodiments, or forms in which structural components and functions in the embodiments are arbitrarily combined, within the scope of the present disclosure. [List of reference symbols] 1 tungsten alloy wire 11 Staff 12 Electrode 13 Twisted wire QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2022-001660

[0003]

Claims

[1] Tungsten alloy wire, wherein the tungsten alloy wire is used in an environment in which the tungsten alloy wire is subjected at least once to a thermal effect at a temperature of at least 1100 degrees Celsius, wherein the tungsten alloy wire Rhenium with a content of at least 5 wt% and at most 26 wt%. [2] A metal product comprising the tungsten alloy wire according to claim 1. [3] A metal product according to claim 2, wherein the metal product is a rod, an electrode or a twisted wire.

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