Cemented carbide stock for rotary tool, and rotary tool

Abstract

To provide a cemented carbide stock for a rotary tool enabling the long life performance of the rotary tool when used as a rotary tool material, and a cutting tool provided therewith.SOLUTION: A cemented carbide stock for a rotary tool comprises tungsten carbide particles, and a bonded phase. The cemented carbide stock includes pores having an equivalent circle diameter of less than 0.2 μm by 9 or less in rectangular one measurement field of 24.9×18.8 μm, and the measurement field is provided at a central part of a cross section of the cemented carbide stock.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a cemented carbide material for a rotary tool and to the rotary tool. [Background technology]

[0002] Cemented carbide alloys comprising tungsten carbide particles and a binder phase containing cobalt are widely used as materials for cutting tools (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-132570 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the demand for cost reduction has become increasingly severe, and rotary tools with long tool life are in demand. Therefore, an object of the present disclosure is to provide a cemented carbide material for rotary tools, and a rotary tool, which, when used as a material for rotary tools, enables the rotary tools to have a long life. [Means for solving the problem]

[0005] The present disclosure provides a cemented carbide material for a rotary tool, comprising: The cemented carbide material comprises tungsten carbide particles and a binder phase, The cemented carbide material contains 9 or less pores having a circular equivalent diameter of less than 0.2 μm in a rectangular measurement field of view of 24.9 μm × 18.8 μm, The measurement field of view is a cemented carbide material for a rotary tool, and is provided at the center of the cross section of the cemented carbide material.

[0006] The present disclosure provides a rotary tool made of cemented carbide, The cemented carbide comprises tungsten carbide particles and a binder phase; The cemented carbide includes 9 or less pores having a circle equivalent diameter of less than 0.2 μm in each of a first measurement field, a second measurement field, and a third measurement field, each of the first measurement field, the second measurement field, and the third measurement field is a rectangle of 24.9 μm×18.8 μm; the first measurement field of view is provided on a cross section of the cemented carbide having a rotation axis P1 of the rotary tool as a normal line so as to include the rotation axis P1; the second measurement field of view is provided on the cross section of the cemented carbide so as to include a position P3 on a line segment L connecting the rotation axis P1 and the cutting edge P2 of the rotary tool, and whose distance from the rotation axis P1 is 1 / 3 of the length L1 of the line segment L; The third measurement field is a rotary tool that is arranged on the cross section of the cemented carbide so as to include a position P4 on the line L and whose distance from the rotation axis P1 is 2 / 3 of the length L1 of the line L. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a rotary tool having a long tool life. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of an image of the cemented carbide material of the first embodiment taken with a scanning electron microscope. [Figure 2] FIG. 2 is a diagram for explaining the position of the measurement field of the cemented carbide material of the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating a method for measuring the number of pores in the cemented carbide of the rotary tool of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. (1) The present disclosure provides a cemented carbide material for a rotary tool, The cemented carbide material comprises tungsten carbide particles and a binder phase, The cemented carbide material contains 9 or less pores having a circular equivalent diameter of less than 0.2 μm in a rectangular measurement field of view of 24.9 μm × 18.8 μm, The measurement field of view is a cemented carbide material for a rotary tool, and is provided at the center of the cross section of the cemented carbide material.

[0010] According to the present disclosure, it is possible to provide a rotary tool having a long tool life.

[0011] (2) The average particle size of the tungsten carbide particles is preferably 0.40 μm or more and 1.00 μm or less, which further improves the tool life of the rotary tool.

[0012] (3) The average particle size of the tungsten carbide particles is preferably 0.40 μm or more and less than 0.80 μm, which further improves the tool life of the rotary tool.

[0013] (4) The cemented carbide material preferably contains 85.0% by volume to 95.5% by volume or less of the tungsten carbide particles and 0.5% by volume to 15.0% by volume or less of the binder phase, which further improves the tool life of the rotary tool.

[0014] (5) The present disclosure provides a rotary tool made of cemented carbide, The cemented carbide comprises tungsten carbide particles and a binder phase; The cemented carbide includes 9 or less pores having a circle equivalent diameter of less than 0.2 μm in each of a first measurement field, a second measurement field, and a third measurement field, each of the first measurement field, the second measurement field, and the third measurement field is a rectangle of 24.9 μm×18.8 μm; the first measurement field of view is provided on a cross section of the cemented carbide having a rotation axis P1 of the rotary tool as a normal line so as to include the rotation axis P1; the second measurement field of view is provided on the cross section of the cemented carbide so as to include a position P3 on a line segment L connecting the rotation axis P1 and the cutting edge P2 of the rotary tool, and whose distance from the rotation axis P1 is 1 / 3 of the length L1 of the line segment L; The third measurement field is a rotary tool that is arranged on the cross section of the cemented carbide so as to include a position P4 on the line L and whose distance from the rotation axis P1 is 2 / 3 of the length L1 of the line L.

[0015] The rotary tools of the present disclosure can have a long tool life.

[0016] [Details of the embodiments of the present disclosure] Specific examples of the presently disclosed cemented carbide material for rotary tools and rotary tools using the same will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately changed for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0017] In this specification, the expression "A to B" means the upper and lower limits of a range (i.e., A or more and B or less), and when no unit is specified for A and a unit is specified only for B, the unit of A and the unit of B are the same.

[0018] In this specification, a pore having a diameter of less than 0.2 μm is also referred to as a “first pore,” and a pore having a diameter of 0.2 μm or more is also referred to as a “second pore.” The first pore and the second pore are collectively referred to as a “pore.”

[0019] In this specification, the term "rotary tool" refers to a tool that rotates around a rotation axis passing through the tool itself to perform machining such as cutting. Examples of such rotary tools include drills and end mills.

[0020] [Embodiment 1: Cemented carbide material for rotary tools] One embodiment of the present disclosure (hereinafter also referred to as "the present embodiment") is a cemented carbide material for a rotary tool (hereinafter also referred to as "the cemented carbide material for a rotary tool"), The cemented carbide material comprises tungsten carbide particles and a binder phase, The cemented carbide material contains 9 or less pores with a circular equivalent diameter of less than 0.2 μm in one rectangular measurement field of view of 24.9 μm × 18.8 μm, The measurement field of view is a cemented carbide material for a rotary tool, and is provided in the center of the cross section of the cemented carbide material.

[0021] <Pore> The cemented carbide material of this embodiment includes 9 or less pores (first pores) with a circle-equivalent diameter of less than 0.2 μm in one rectangular measurement field of 24.9 μm × 18.8 μm, and the measurement field is provided in the center of the cross section of the cemented carbide material. A cemented carbide material having 9 or less first pores in the measurement field of view has excellent rigidity. Therefore, a rotary tool made using this cemented carbide material has excellent straightness and a long tool life. Furthermore, when the number of first pores in the cemented carbide material is small, fractures originating from the first pores are less likely to occur. Therefore, a rotary tool made using this cemented carbide material has excellent fracture resistance and a long tool life.

[0022] The number of first pores in the measurement field of the cemented carbide material is 9 or less, preferably 7 or less, preferably 5 or less, preferably 3 or less, and most preferably 0. The number of the first pores is preferably 0 to 9, preferably 0 to 7, preferably 0 to 5, preferably 0 to 3, and most preferably 0.

[0023] The cemented carbide material of this embodiment preferably does not include second pores having a circle equivalent diameter of 0.2 μm or more in the measurement field, which allows the cemented carbide material to have high rigidity and excellent fracture resistance.

[0024] In this specification, the methods for measuring the number of first pores and second pores in the above-mentioned measurement field of view of the cemented carbide material are as follows (A1) to (H1).

[0025] (A1) A cemented carbide material is cut out so that a cross section normal to its longitudinal direction (axis) is exposed, and the cross section is mirror-finished. Since cemented carbide materials for rotary tools are usually in the shape of a round bar, the longitudinal direction of the cemented carbide material corresponds to the extension direction of the rotation axis of the rotary tool obtained by machining the cemented carbide material. Examples of mirror-finishing methods include polishing with diamond paste, using a focused ion beam device (FIB device), using a cross-section polisher device (CP device), and a combination of these methods.

[0026] (B1) The mirror-finished surface of the cemented carbide material is analyzed using energy dispersive X-ray spectroscopy (SEM-EDX) to identify the elements contained in the cemented carbide material.

[0027] (C1) The mirror-finished surface of the cemented carbide material is photographed with a scanning electron microscope to obtain a photographed image. The photographed area of ​​the photographed image is set to the center of the cross section of the cemented carbide material, that is, a position that does not include areas with properties clearly different from the bulk part, such as the surface vicinity of the cemented carbide material (a position where the entire photographed area is the bulk part of the cemented carbide material). The observation magnification is 5000x.

[0028] FIG. 1 is an example of an image of a cemented carbide material 1 of this embodiment taken with a scanning electron microscope. In the scale at the bottom right of FIG. 1, one graduation represents 1 μm. In FIG. 1, the cemented carbide material 1 contains pores 2. Note that, as shown in FIG. 1, the pores 2 may be very small and difficult to identify in the image taken with the scanning electron microscope. However, as will be explained in (F1) below, the pores can be identified by superimposing the image taken with the scanning electron microscope after binarization processing on an element mapping image.

[0029] (D1) The imaging region of (C1) above is analyzed using energy dispersive X-ray spectroscopy (SEM-EDX) to identify the distribution of the elements identified in (B1) above in the imaging region, and an elemental mapping image is obtained. In the elemental mapping image, no elements are present in the pore region.

[0030] (E1) The photographed image obtained in (C1) above is imported into a computer, and image processing and binarization are performed using image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ). Specifically, after importing the photographed image into the computer, the "Make Binary" button on the computer screen is pressed, and binarization processing is performed under the conditions preset in the image analysis software. In the image after binarization processing, the tungsten carbide particles are shown in the lightest color (white), and the binder phase and pores are shown in black.

[0031] (F1) By superimposing the elemental mapping image obtained in (D1) above on the binarized image obtained in (E1) above, the pore presence region is identified on the binarized image. Specifically, among the regions shown in black in the binarized image, the regions where no elements are present in the elemental mapping image correspond to the pore presence region.

[0032] (G1) A rectangular measurement field of view of 24.9 μm × 18.8 μm is set in the obtained binarized image. Based on the number of pixels in the area identified as a pore in the measurement field of view, the equivalent circle diameter of the pore (Heywood diameter: diameter equivalent to a circle with an equal area) is calculated using the image analysis software.

[0033] (H1) Based on the calculation results of (G1) above, the number of first pores in the measurement field having a circle-equivalent diameter of less than 0.2 μm and the number of second pores having a circle-equivalent diameter of 0.2 μm or more are measured.

[0034] As far as the applicant has measured, as long as measurements are performed on the same sample, even when the cut-out location of the cross-section of the cemented carbide material is arbitrarily set, the photographing area described in (C1) above is arbitrarily set on the cross-section, and the number of first pores and second pores is measured multiple times according to the procedures (B1) to (H1) above, there is little variance in the measurement results, and it has been confirmed that arbitrarily setting the cut-out location of the cross-section of the cemented carbide material and arbitrarily setting the photographing area of ​​the photographed image are not arbitrary. For example, as shown in Figure 2, even when a total of five photographing areas are set on the cross-section of cemented carbide material 1 so as to include central portion A and positions A1, A2, A3, and A4 that are the same distance from central portion A, and the number of first pores and second pores is measured at each of the five positions according to the procedures (B1) to (H1) above, there is little variance in the measurement results, and it has been confirmed that arbitrarily setting the photographing area of ​​the photographed image is not arbitrary.

[0035] <Tungsten carbide particles> ≪Composition≫ Tungsten carbide particles (hereinafter also referred to as "WC particles") are particles made of tungsten carbide. Here, the tungsten carbide may be pure tungsten carbide containing no impurity elements, or may be tungsten carbide containing impurity elements as long as the effects of the present disclosure are not impaired. The content of impurities contained in tungsten carbide (when two or more elements constitute the impurities, the total concentration of these elements) is preferably less than 0.1 mass% relative to the total amount of WC particles. The content of impurities in the WC particles is measured by ICP (Inductively Coupled Plasma) Emission Spectroscopy (measuring device: Shimadzu Corporation "ICPS-8100" (trademark)).

[0036] ≪Average particle size≫ The average particle size of the tungsten carbide particles in this embodiment is preferably 0.40 μm or more and 1.00 μm or less, more preferably 0.40 μm or more and less than 0.80 μm, and even more preferably 0.42 μm or more and less than 0.80 μm, which further improves the tool life.

[0037] In this specification, the average particle size of tungsten carbide particles contained in a cemented carbide material means the D50 (the circle equivalent diameter at which the cumulative number-based frequency is 50%, the median diameter D50) of the equivalent area diameter (Heywood diameter) of WC particles contained in the cemented carbide material. The methods for measuring the particle size of each particle to calculate the average particle size of the WC particles are as follows (A2) to (B2).

[0038] (A2) By superimposing an elemental mapping image obtained by the same method as (A1) to (E1) described in the method for measuring the number of first pores and second pores in the above measurement field of view of a cemented carbide material on the image after binarization processing, the region where tungsten carbide particles exist is identified on the image after binarization processing. Specifically, the region shown in the lightest color (white) in the image after binarization processing and where tungsten (W) and carbon (C) exist in the elemental mapping image corresponds to the region where tungsten carbide particles exist.

[0039] (B2) A rectangular measurement field of view measuring 24.9 μm × 18.8 μm is set in the image after the binarization process. Using the image analysis software, the circle-equivalent diameter (Heywood diameter: diameter equivalent to a circle with an equal area) of each tungsten carbide particle in the measurement field of view is calculated.

[0040] As far as the applicant has measured, as long as measurements are made on the same sample, even when the cut-out location of the cross section of the cemented carbide material is arbitrarily set, the photographing area described in (C1) above is arbitrarily set on the cross section, and the average particle size of tungsten carbide particles is measured multiple times according to the procedures in (A2) and (B2) above, there is little variation in the measurement results, and it has been confirmed that arbitrarily setting the cut-out location of the cross section of the cemented carbide material and arbitrarily setting the photographing area of ​​the photographed image are not arbitrary.

[0041] <Binded phase> The cemented carbide of this embodiment includes a binder phase. The binder phase preferably includes cobalt as a main component. Here, "the binder phase includes cobalt as a main component" means that the cobalt content in the binder phase is 90% by mass or more and 100% by mass or less. The cobalt content in the binder phase can be measured by ICP atomic emission spectroscopy (instrument used: Shimadzu Corporation's "ICPS-8100" (trademark)).

[0042] In addition to cobalt, the binder phase may include chromium, vanadium, nickel, tungsten, titanium, niobium, tantalum, and the like.

[0043] <Composition of cemented carbide material> The cemented carbide material of this embodiment preferably contains 85.0% to 95.5% by volume of tungsten carbide particles and 0.5% to 15.0% by volume of a binder phase, which further improves the tool life of a rotary tool using the cemented carbide material.

[0044] The lower limit of the content of tungsten carbide particles in the cemented carbide material can be 85.0 vol% or more, 88.0 vol% or more, or 90.0 vol% or more. The upper limit of the content of tungsten carbide particles in the cemented carbide material can be 99.5 vol% or less, or 95.0 vol% or less. The content of tungsten carbide particles in the cemented carbide material can be 85.0 vol% to 99.5 vol%, 88.0 vol% to 99.5 vol%, 90.0 vol% to 99.5 vol%, 85.0 vol% to 95.0 vol%, 88.0 vol% to 95.0 vol%, or 90.0 vol% to 95.0 vol%.

[0045] The lower limit of the binder phase content in the cemented carbide material can be 0.5 volume % or more, or 5.0 volume % or more. The upper limit of the binder phase content in the cemented carbide material can be 15.0 volume % or less, 12.0 volume % or less, or 10.0 volume % or less. The binder phase content in the cemented carbide material can be 0.5 volume % to 15.0 volume % or less, 5.0 volume % to 15.0 volume % or less, 0.5 volume % to 12.0 volume % or less, 5.0 volume % to 12.0 volume % or less, 0.5 volume % to 10.0 volume % or less, or 5.0 volume % to 10.0 volume %.

[0046] The cemented carbide material may contain 85.0 to 99.5 volume % tungsten carbide particles and 0.5 to 15.0 volume % binder phase. The cemented carbide material may contain 88.0 to 99.5 volume % tungsten carbide particles and 0.5 to 12.0 volume % binder phase. The cemented carbide material may contain 90.0 to 99.5 volume % tungsten carbide particles and 0.5 to 10 volume % binder phase. The cemented carbide material may contain 85.0 to 95.0 volume % tungsten carbide particles and 5.0 to 15.0 volume % binder phase. The cemented carbide material may include 88.0 to 95.0 volume % tungsten carbide particles and 5.0 to 12.0 volume % binder phase. The cemented carbide material may include 90.0 to 95.0 volume % tungsten carbide particles and 5.0 to 10.0 volume % binder phase.

[0047] The cemented carbide material may be composed of tungsten carbide particles and a binder phase. The cemented carbide material may contain, in addition to the tungsten carbide particles and binder phase, hard phase particles other than tungsten carbide and / or impurities. Examples of the hard phase particles include titanium, niobium, and tantalum. The impurity content of the cemented carbide material may be 0.1 mass% or less. The cemented carbide material may be composed of tungsten carbide particles, a binder phase, and impurities. The cemented carbide material may be composed of tungsten carbide particles, a binder phase, and hard phase particles. The cemented carbide material may be composed of tungsten carbide particles, a binder phase, hard phase particles, and impurities.

[0048] The methods for measuring the content (volume %) of the tungsten carbide particles and the binder phase in the cemented carbide material are as follows (A3) to (B3).

[0049] (A3) By superimposing an elemental mapping image obtained by the same method as (A1) to (E1) described in the method for measuring the number of first pores and second pores in the above measurement field of view of a cemented carbide material on the binarized image, the regions where tungsten carbide particles exist and the regions where binder phases exist are identified on the binarized image. Specifically, the regions shown in the lightest color (white) in the binarized image and where tungsten (W) and carbon (C) exist correspond to the regions where tungsten carbide particles exist. The regions shown in black in the binarized image and where cobalt (Co) exists correspond to the regions where binder phases exist.

[0050] (B3) A rectangular measurement field of view of 24.9 μm × 18.8 μm is set in the image after the binarization process. Using the image analysis software, the area percentages of the tungsten carbide particles and the binder phase are measured, with the area of ​​the entire measurement field being used as the denominator. In this specification, the area percentage of the tungsten carbide particles corresponds to the content (volume %) of tungsten carbide particles in the cemented carbide material, and the area percentage of the binder phase corresponds to the content (volume %) of the binder phase in the cemented carbide material.

[0051] When the cemented carbide material contains hard phase particles in addition to WC particles and a binder phase, the area where the hard phase particles exist is identified in (A3) above, and the area percentage of the hard phase particles is measured in (B3) above. The area percentage of the hard phase particles corresponds to the content (volume %) of the hard phase particles in the cemented carbide material.

[0052] As far as the applicant has measured, as long as measurements are made on the same sample, even when the cut-out location of the cross section of the cemented carbide material is arbitrarily set, the photographing area described in (C1) above is arbitrarily set on the cross section, and the area percentages of tungsten carbide particles, binder phase, hard phase particles, and impurities are measured multiple times according to the procedures in (A3) and (B3) above, there is little variation in the measurement results, and it has been confirmed that arbitrarily setting the cut-out location of the cross section of the cemented carbide material and arbitrarily setting the photographing area of ​​the photographed image are not arbitrary.

[0053] <Method of manufacturing cemented carbide materials for rotary tools> The cemented carbide material for rotary tools of this embodiment can be manufactured by carrying out the steps of preparing raw material powder, mixing, granulating, molding, sintering, HIP treatment, and cooling in the above order. Each step will be described below.

[0054] ≪Preparation process≫ The preparation step is a step of preparing raw material powders of materials constituting the cemented carbide material. Examples of raw material powders include tungsten carbide powder, which is the raw material for tungsten carbide particles, cobalt (Co) powder, which is the raw material for the binder phase, and chromium carbide (Cr3C2) powder and vanadium carbide (VC) powder, which are grain growth inhibitors. Furthermore, hard phase powders, which are the raw materials for the hard phase particles, can also be used. Commercially available tungsten carbide powder, cobalt powder, chromium carbide powder, vanadium carbide powder, and hard phase powders can be used.

[0055] The average particle size of the tungsten carbide powder can be 0.7 μm or more and 1.3 μm or less. The average particle size of the cobalt powder can be 0.8 μm or more and 1.2 μm or less. The average particle size of the chromium carbide powder can be 1.0 μm or more and 2.0 μm or less. The average particle size of the vanadium carbide powder can be 0.5 μm or more and 1.0 μm or less. The average particle size of the hard phase powder can be 0.2 μm or more and 2.0 μm or less. In this specification, the average particle size of the raw material powder means the median diameter d50 of the spherical equivalent diameter of the raw material powder. The average particle size of the raw material powder is measured using a particle size distribution measuring device manufactured by Microtrac (product name: MT3300EX).

[0056] ≪Mixing process≫ The mixing step is a step of mixing the raw material powders prepared in the preparation step, and a mixed powder in which the raw material powders are mixed is obtained by the mixing step.

[0057] The proportion of tungsten carbide powder in the mixed powder can be, for example, 84% by mass or more and 99.5% by mass or less. The proportion of cobalt powder in the mixed powder can be, for example, 0.5% by mass or more and 15% by mass or less. The proportion of chromium carbide powder in the mixed powder can be, for example, 0.1% by mass or more and 1.2% by mass or less. The proportion of vanadium carbide powder in the mixed powder can be, for example, 0% by mass or more and 0.2% by mass or less.

[0058] An attritor or a ball mill can be used to mix the raw material powders. The mixing time in an attritor can be 5 hours or more and 20 hours or less. The mixing time in a ball mill can be 20 hours or more and 70 hours or less.

[0059] ≪Pelletization process≫ The mixed powder obtained by mixing is dried in a hot water bath to obtain a dry raw material powder. A mixed solution is prepared by mixing polyethylene oxide (weight average molecular weight (Mw): approximately 100,000) and glycerin in a volume ratio of 1:1. The mixed solution is sprayed onto the dry raw material powder to granulate it. Hereinafter, the mixed solution sprayed onto the dry raw material powder will also be referred to as the binder.

[0060] ≪Molding process≫ The compacting step is a step of forming the mixed powder obtained in the mixing step into a shape suitable for a rotary tool (e.g., a round bar shape) to obtain a compact. The compacting method and conditions in the compacting step are not particularly limited and may be any general method and conditions.

[0061] <Sintering process> The sintering step is a step of sintering the compact obtained in the compacting step to obtain a cemented carbide material. The sintering step can be performed in the following manner.

[0062] The compact is placed in a sintering furnace and heated to 800°C at a rate of 0.5°C / min in a vacuum (1.0 Pa or less).

[0063] Next, N2 gas is introduced into the sintering furnace, and the material is heated to 1200°C at a temperature increase rate of 0.5°C / min under an N2 gas atmosphere (30 kPaG).The sintering furnace is then evacuated (1.0 Pa or less), and the material is heated to 1370°C at a temperature increase rate of 0.5°C / min.Ar gas is then introduced into the sintering furnace, and the material is maintained at 1370°C under an Ar gas atmosphere (140 kPaG) for 120 to 240 minutes to obtain a cemented carbide material.

[0064] <HIP processing process> The HIP process is a process in which the sintered cemented carbide material is subjected to HIP (Hot Isostatic Pressing). For example, the cemented carbide material can be subjected to a temperature of 1320°C and a pressure of 10 MPa for 60 minutes using Ar gas as a pressure medium.

[0065] ≪Cooling process≫ The cooling step is a step of cooling the cemented carbide material after the HIP treatment, for example, by rapidly cooling the cemented carbide material after the HIP treatment in Ar gas.

[0066] <Features of the manufacturing method of the cemented carbide material according to the present embodiment> The cemented carbide material obtained by the above manufacturing method has 9 or fewer pores with a circular equivalent diameter of less than 0.2 μm in a rectangular measurement field of view of 24.9 μm × 18.8 μm. The reason for this is presumed to be as follows.

[0067] It is believed that pores in the cemented carbide material are formed by the evaporation of the binder during the sintering process. In the above manufacturing method, a mixed solution of polyethylene oxide and glycerin is used as the binder in the granulation process, and the temperature rise rate in the sintering process is slow. The binder has a large molecular weight and is difficult to evaporate. Therefore, in the above manufacturing method, when the temperature is raised in the sintering process, the binder evaporates almost simultaneously inside and near the surface of the compact, and the binder does not remain inside the compact but is easily discharged to the outside. Furthermore, in the above sintering process, the compact is held at the maximum temperature (1370°C) in an Ar gas atmosphere (140 kPaG) for a certain period of time (120 minutes). Pressurizing the compact at a high temperature causes the structure to flow and the pores to become smaller. Therefore, pores are unlikely to exist inside the cemented carbide material after sintering, and the number of pores is reduced throughout. Furthermore, even if pores exist, their size is very small. As a result of extensive research, the present inventors have newly discovered that by using a mixed solution of polyethylene oxide and glycerin as a binder and slowing down the rate of temperature rise in the sintering process, it is possible to obtain a cemented carbide material having 9 or fewer pores with an equivalent circle diameter of less than 0.2 μm in a rectangular measurement field of view of 24.9 μm × 18.8 μm.

[0068] On the other hand, in conventional methods for manufacturing cemented carbide materials, granulation is performed by spray drying from the viewpoint of efficiency, and polyethylene glycol, which is suitable for spray drying, is used as a binder. Polyethylene glycol has a small molecular weight and is easily vaporized. Note that polyethylene oxide used in this embodiment cannot be used for spray drying because it causes clogging of the spray dryer. Furthermore, in conventional methods for manufacturing cemented carbide materials, from the viewpoint of efficiency, the temperature rise rate during sintering is set to 10 to 20°C / min, and sintering at the maximum temperature is performed under reduced pressure or vacuum. Therefore, while the binder near the surface of the compact is easily vaporized during temperature rise, the binder inside the compact is less likely to vaporize. Therefore, the cemented carbide material after sintering is prone to have pores inside, which makes the structure non-uniform.

[0069] [Embodiment 2: Rotary tool] This embodiment is a rotary tool made of cemented carbide, The cemented carbide comprises tungsten carbide particles and a binder phase; The cemented carbide contains 9 or less pores having a circle equivalent diameter of less than 0.2 μm in each of the first measurement field, the second measurement field, and the third measurement field, each of the first measurement field, the second measurement field, and the third measurement field is a rectangle of 24.9 μm × 18.8 μm; the first measurement field of view is provided on a cross section of the cemented carbide having a normal line parallel to a rotation axis P1 of the rotary tool so as to include the rotation axis P1; the second measurement field of view is provided on the cross section of the cemented carbide so as to include a position P3 on a line segment L connecting the rotation axis P1 and the cutting edge P2 of the rotary tool, and whose distance from the rotation axis P1 is 1 / 3 of the length L1 of the line segment L; The third measurement field of view is a rotary tool that is positioned on the cross section of the cemented carbide to include a position P4 on the line L and at a distance from the rotation axis P1 that is 2 / 3 of the length L1 of the line L.

[0070] Examples of the rotary tool of this embodiment include a drill and an end mill. The rotary tool of this embodiment may be entirely made of the above-mentioned cemented carbide alloy. Alternatively, a part of the rotary tool may be made of the above-mentioned cemented carbide alloy. Here, "a part of the rotary tool made of the above-mentioned cemented carbide alloy" refers to an embodiment in which at least the part of the drill or end mill involved in cutting (for example, the body part other than the shank) is made of the above-mentioned cemented carbide alloy.

[0071] <Pore> The cemented carbide constituting the rotary tool of this embodiment includes 9 or less pores (first pores) with a circle equivalent diameter of less than 0.2 μm in each of the first measurement field, the second measurement field, and the third measurement field. The cemented carbide constituting the rotary tool of this embodiment has excellent rigidity. Therefore, the rotary tool of this embodiment has excellent straightness and a long tool life. Furthermore, when the number of first pores in the cemented carbide is small, fractures originating from the first pores are less likely to occur. Therefore, the rotary tool using this cemented carbide has excellent fracture resistance and a long tool life.

[0072] The number of first pores in each of the first measurement field, the second measurement field, and the third measurement field of the cemented carbide is preferably 9 or less, preferably 7 or less, preferably 5 or less, preferably 3 or less, and most preferably 0. The number of the first pores is preferably 0 to 9, preferably 0 to 7, preferably 0 to 5, preferably 0 to 3, and most preferably 0.

[0073] In the rotary tool of this embodiment, it is preferable that the first measurement field, the second measurement field, and the third measurement field of the cemented carbide do not contain second pores having a circle equivalent diameter of 0.2 μm or more, which allows the rotary tool to have high rigidity and excellent fracture resistance.

[0074] In this specification, the methods for measuring the number of first pores and second pores in the first measurement field, the second measurement field, and the third measurement field of the cemented carbide constituting the rotary tool are as follows (A4) to (H4).

[0075] (A4) The cemented carbide constituting the rotary tool is cut out so that a cross section normal to the rotation axis of the rotary tool is exposed, and the cross section is mirror-polished. Examples of mirror-polishing methods include polishing with diamond paste, using a focused ion beam device (FIB device), using a cross-section polisher device (CP device), and combinations of these methods.

[0076] (B4) The mirror-finished cross section of the cemented carbide is analyzed using energy dispersive X-ray spectroscopy (SEM-EDX) to identify the elements contained in the cemented carbide.

[0077] (C4) The above cross section of the cemented carbide is photographed with a scanning electron microscope. When photographing, the photographing area is set to include the rotation axis P1 and cutting edge P2 of the rotary tool 3, as shown in Figure 3. The observation magnification is 5000x. In the above cross section, the length L1 of the line segment L connecting the rotation axis P1 and cutting edge P2 is 1 / 2 of the diameter D of the rotary tool.

[0078] (D4) The imaging region of (C4) above is analyzed using energy dispersive X-ray spectroscopy (SEM-EDX), the distribution of the elements identified in (B4) above in the imaging region is identified, and an elemental mapping image is obtained. In the elemental mapping image, no elements are present in the pore region.

[0079] (E4) The image obtained in (C4) above is imported into a computer, and image processing and binarization are performed using image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ). Specifically, after importing the image into the computer, the "Make Binary" button on the computer screen is pressed, and binarization is performed under the conditions preset in the image analysis software. In the image after binarization, the tungsten carbide particles are shown in the lightest color (white), and the binder phase and pores are shown in black.

[0080] (F4) By superimposing the elemental mapping image obtained in (D4) above on the binarized image obtained in (E4) above, the pore presence region is identified on the binarized image. Specifically, among the regions shown in black in the binarized image, the regions where no elements are present in the elemental mapping image correspond to the pore presence region.

[0081] (G4) A first measurement field, a second measurement field, and a third measurement field are set in the obtained image after binarization. Each of the first measurement field, the second measurement field, and the third measurement field is a rectangle of 24.9 μm × 18.8 μm. The method for setting the positions of the first measurement field, the second measurement field, and the third measurement field will be described with reference to FIG. 3. As shown in FIG. 3, a line segment L is drawn in the image after binarization, connecting the rotation axis P1 of the rotary tool 3 and the cutting edge P2 of the rotary tool (in FIG. 2, the line segment L is shown by a dotted line). A position P3 is set on the line segment L, the distance from the rotation axis P1 being 1 / 3 of the length L1 of the line segment L. A position P4 is set on the line segment L, the distance from the rotation axis P1 being 2 / 3 of the length L1 of the line segment L. The first measurement field is set to include the rotation axis P1. The second measurement field is set to include the position P3. The third measurement field is set to include the position P4. If the groove 4 of the rotating tool is deep and the entire third measurement field cannot be set on the cross section of the rotating tool, the third measurement field is set as follows: In the image after the above binarization process, a circle R1 is drawn with its center at the rotation axis P1 and its radius is 2 / 3 of the length L1 of the line segment L. The third measurement field is set so that it includes any point on the circle R1 and so that the entire measurement field is located on the cross section of the rotating tool.

[0082] In each of the three measurement fields, the equivalent circle diameter of the pore (Heywood diameter: equivalent circle diameter with equal area) is calculated using the image analysis software based on the number of pixels in the area identified as a pore in the measurement field.

[0083] (H4) Based on the calculation results of (G4) above, the number of first pores having an equivalent circle diameter of less than 0.2 μm and the number of second pores having an equivalent circle diameter of 0.2 μm or more in each measurement field are measured. If the number of first pores is 9 or less in all three measurement fields of the cemented carbide constituting the rotary tool, the cemented carbide is determined to contain 9 or less pores having an equivalent circle diameter of less than 0.2 μm in each of the first measurement field, the second measurement field, and the third measurement field.

[0084] As far as the applicant has measured, as long as measurements are made on the same sample, even if the cut-out location of the cemented carbide cross section is arbitrarily set and the position of the measurement field of view is arbitrarily set according to the above procedures (B4) to (H4), and the number of first pores and second pores is measured multiple times, there is little variation in the measurement results, and it has been confirmed that arbitrarily setting the cut-out location of the cemented carbide cross section and arbitrarily setting the position of the measurement field of view is not arbitrary.

[0085] <Tungsten carbide particles> ≪Composition≫ The composition of the tungsten carbide particles in this embodiment can be the same as the composition of the tungsten carbide particles described in the first embodiment.

[0086] ≪Average particle size≫ In this embodiment, the average particle size (median diameter D50 of the equivalent circle diameter) of the tungsten carbide particles is preferably 0.40 μm or more and 1.00 μm or less, more preferably 0.40 μm or more and less than 0.80 μm, and even more preferably 0.42 μm or more and less than 0.80 μm. This further improves the tool life.

[0087] In this specification, the average particle size of tungsten carbide particles contained in the cemented carbide of a rotary tool refers to the D50 (median diameter D50, the diameter equivalent to a circle with an equivalent area) of the WC particles contained in the cemented carbide (Heywood diameter) at which the cumulative frequency based on the number of particles is 50%). The methods for measuring the particle size of each particle to calculate the average particle size (median diameter D50 of the equivalent circle diameter) of the tungsten carbide particles are as follows (A5) to (B5).

[0088] (A5) By superimposing an elemental mapping image obtained by the same method as (A4) to (E4) described in the method for measuring the number of first pores and second pores in a cemented carbide alloy of a rotary tool on the binarized image, the region where tungsten carbide particles exist is identified on the binarized image. Specifically, the region shown in the lightest color (white) in the binarized image and where tungsten (W) and carbon (C) exist in the elemental mapping image corresponds to the region where tungsten carbide particles exist.

[0089] (B5) A first measurement field, a second measurement field, and a third measurement field are set in the image after the binarization process. Using the image analysis software, the equivalent area circle diameter (Heywood diameter) of each tungsten carbide particle is calculated for each of the three measurement fields. The average value of the average particle diameters (median diameter D50 of the equivalent area circle diameters) of the tungsten carbide particles in the three measurement fields is calculated. In this specification, this average value corresponds to the average particle diameter of the tungsten carbide particles contained in the cemented carbide of the rotary tool.

[0090] As far as the applicant has measured, as long as measurements are made on the same sample, even when the cut-out location of the cemented carbide cross section is arbitrarily set and the position of the measurement field is arbitrarily set according to the procedures (B4) to (H4) above, and the average particle size of tungsten carbide particles is measured multiple times, there is little variation in the measurement results, and it has been confirmed that arbitrarily setting the cut-out location of the cemented carbide cross section and arbitrarily setting the position of the measurement field is not arbitrary.

[0091] <Binded phase> The composition of the binder phase in this embodiment can be the same as the composition of the binder phase described in the first embodiment.

[0092] <Composition of cemented carbide> The composition of the cemented carbide in this embodiment (content of tungsten carbide particles in the cemented carbide, content of the binder phase in the cemented carbide, constituent components, etc.) can be the same as the composition of the cemented carbide material described in the first embodiment.

[0093] The methods for measuring the respective contents (volume %) of tungsten carbide particles and binder phase in the cemented carbide of the rotary tool are as follows (A6) to (B6).

[0094] (A6) By superimposing an elemental mapping image obtained by the same method as (A4) to (E4) described in the method for measuring the number of first pores and second pores in a cemented carbide alloy for a rotary tool on the binarized image, the regions where tungsten carbide particles exist and the regions where binder phases exist are identified on the binarized image. Specifically, the regions shown in the lightest color (white) in the binarized image and where tungsten (W) and carbon (C) exist correspond to the regions where tungsten carbide particles exist. The regions shown in black in the binarized image and where cobalt (Co) exists correspond to the regions where binder phases exist.

[0095] (B6) A first measurement field, a second measurement field, and a third measurement field are set in the obtained image after binarization processing. Using the image analysis software, the area percentages of the tungsten carbide particles and the binder phase are measured in each of the three measurement fields, with the area of ​​the entire measurement field as the denominator. The average value of the area percentages of the tungsten carbide particles in the three measurement fields is calculated. In this specification, this average value corresponds to the content (volume %) of tungsten carbide particles in the cemented carbide of the rotary tool. The average value of the area percentages of the binder phase in the three measurement fields is calculated. In this specification, this average value corresponds to the content (volume %) of the binder phase in the cemented carbide of the rotary tool.

[0096] As far as the applicant has measured, as long as measurements are made on the same sample, even when the cut-out location of the cemented carbide cross section is arbitrarily set and the position of the measurement field is arbitrarily set according to the above procedures (B4) to (H4), and measurements of the tungsten carbide particle content and the binder phase content are made multiple times, there is little variation in the measurement results, and it has been confirmed that arbitrarily setting the cut-out location of the cemented carbide cross section and arbitrarily setting the position of the measurement field are not arbitrary.

[0097] The rotary tool according to this embodiment may further include a hard film that covers at least a part of the surface of the substrate made of cemented carbide. The hard film may be made of, for example, diamond-like carbon or diamond.

[0098] <Manufacturing method of rotary tools> The rotary tool of this embodiment can be obtained, for example, by processing the cemented carbide material for the rotary tool of embodiment 1. During processing, the cemented carbide material is processed so as not to include any portion whose properties are clearly different from those of the bulk portion, such as the vicinity of the surface thereof.

[0099] [Appendix 1] The present disclosure provides a cemented carbide material for a rotary tool, comprising: The cemented carbide material comprises tungsten carbide particles and a binder phase, The cemented carbide material contains 0 to 9 pores having a circular equivalent diameter of less than 0.2 μm in a rectangular measurement field of view of 24.9 μm × 18.8 μm, and does not contain pores having a circular equivalent diameter of 0.2 μm or more, The measurement field of view is a cemented carbide material for a rotary tool, and is provided at the center of the cross section of the cemented carbide material. [Appendix 2] The present disclosure provides a rotary tool made of cemented carbide, The cemented carbide comprises tungsten carbide particles and a binder phase; The cemented carbide contains 9 or less pores having a circle equivalent diameter of less than 0.2 μm in each of the first measurement field, the second measurement field, and the third measurement field, and does not contain pores having a circle equivalent diameter of 0.2 μm or more, each of the first measurement field, the second measurement field, and the third measurement field is a rectangle of 24.9 μm×18.8 μm; the first measurement field of view is provided on a cross section of the cemented carbide having a rotation axis P1 of the rotary tool as a normal line so as to include the rotation axis P1; the second measurement field of view is provided on the cross section of the cemented carbide so as to include a position P3 on a line segment L connecting the rotation axis P1 and the cutting edge P2 of the rotary tool, and whose distance from the rotation axis P1 is 1 / 3 of the length L1 of the line segment L; The third measurement field is a rotary tool that is arranged on the cross section of the cemented carbide so as to include a position P4 on the line L and whose distance from the rotation axis P1 is 2 / 3 of the length L1 of the line L. [Example]

[0100] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0101] <Preparation of cemented carbide materials> The cemented carbide materials for each sample were prepared using the following procedure: Seven cemented carbide materials were prepared for each sample. ≪Preparation process≫ As raw material powders, tungsten carbide (WC) powder, cobalt (Co) powder, chromium carbide (Cr3C2) powder, and vanadium carbide (VC) powder were prepared.

[0102] The tungsten carbide powders used were tungsten carbide powders "WC08" (average particle size 0.7-0.9 μm), "WC10" (average particle size 0.9-1.1 μm), and "WC12" (average particle size 1.1-1.3 μm) manufactured by A.L.M.T. Corp. The tungsten carbide powder used in each sample is shown in the "WC powder" column in Table 1.

[0103] The average particle size of the cobalt (Co) powder was 1 μm, the average particle size of the vanadium carbide (VC) powder was 0.8 μm, and the average particle size of the chromium carbide (Cr3C2) powder was 1 μm. The Co powder, VC powder, and Cr3C2 powder were commercially available products. The average particle size of the raw material powders was measured using a particle size distribution analyzer (product name: MT3300EX) manufactured by Microtrac Corporation.

[0104] ≪Mixing process≫ The core raw material powders were mixed in the amounts shown in the "Mixed Powder (mass%)" column of Table 1 to prepare mixed powders. For example, the notation "0.1Cr3C2-0.2VC-10Co-balance WC" in the "Mixed Powder (mass%)" column for Sample 1 indicates that the mixed powder contained 0.1 mass% Cr3C2 powder, 0.2 mass% VC powder, and 10 mass% Co powder, with the remainder (89.7 mass%) being WC powder. Mixing was performed using an attritor (indicated as "ATR" in Table 1). The mixing time in the attritor is shown in the "Mixing / hour" column of Table 1. For example, the mixing time for Sample 1 was 15 hours.

[0105] ≪Pelletization process≫ The mixed powder obtained by mixing was dried in a hot water bath to obtain a dry raw material powder. A mixed solution was prepared by mixing polyethylene oxide (weight average molecular weight (Mw): approximately 100,000) and glycerin at a volume ratio of 1:1. The mixed solution was sprayed onto the dry raw material powder to granulate it.

[0106] ≪Molding process≫ The obtained granulated powder was press-molded to prepare a round rod-shaped compact having a diameter of 3.4 mm.

[0107] <Sintering process> The compact was placed in a sintering furnace and heated to 800°C at a heating rate of 0.5°C / min in a vacuum (1.0 Pa or less). N2 gas was then introduced into the sintering furnace, and the compact was heated to 1200°C under a N2 gas atmosphere (30 kPaG) at the heating rate shown in the "Heating Rate (°C / min)" column for "800°C to 1200°C" in the "Sintering Process" section of Table 1. The sintering furnace was then evacuated (1.0 Pa or less), and the compact was heated to 1370°C at a heating rate of 0.5°C / min. The compact was then held at 1370°C in the atmosphere shown in the "Atmosphere" column for "1370°C" in the "Sintering Process" section of Table 1 for the time shown in the "Holding Time (min)" column for "1370°C" in the "Sintering Process" section of Table 1, to obtain a cemented carbide material.

[0108] <HIP processing process> Next, the sintered cemented carbide material was subjected to HIP treatment. Specifically, the cemented carbide material was subjected to a temperature of 1320°C and a pressure of 10 MPa for 60 minutes using Ar gas as a pressure medium.

[0109] ≪Cooling process≫ Subsequently, the cemented carbide material after the HIP treatment was cooled.

[0110] <Manufacturing of rotary tools> Round bars made of cemented carbide materials of Samples 1 to 8, 1-1 and 1-2 were machined to produce five small-diameter drills with a diameter of 0.2 mm.

[0111] Round bars made of cemented carbide materials of Sample 9 and Sample 1-3 were machined to produce five three-blade end mills with a diameter of φ3 mm.

[0112] [Table 1]

[0113] [evaluation] <Cemented carbide material> The cemented carbide material of each sample before being processed into a rotary tool was measured for its composition, average particle size of the tungsten carbide particles, composition of the binder phase, and number of pores.

[0114] <Composition of cemented carbide material> The content (volume %) of tungsten carbide particles and binder phase was measured for each sample of cemented carbide material. The specific measurement method is described in embodiment 1, and therefore the description will not be repeated. The content (volume %) of binder phase is shown in the "volume %" column of "Binder phase" under "Cemented Carbide Material" in Table 2. In all samples, the total of the volume % of WC particles, the volume % of binder phase, and the volume % of pores was 100 volume %.

[0115] <Average particle size of tungsten carbide particles> The average particle size of the tungsten carbide particles was measured for each sample of cemented carbide material. The specific measurement method is described in embodiment 1, and therefore the description will not be repeated. The results are shown in the "Average particle size (μm)" column of "WC particles" under "Cemented carbide material" in Table 2.

[0116] <Composition of binder phase> The composition of the binder phase of each cemented carbide material sample was measured by ICP atomic emission spectroscopy. It was confirmed that the binder phase in all samples contained Co, Cr, and V. It was also confirmed that the binder phase in all samples contained 90 mass% or more of cobalt.

[0117] Number of pores For each sample of cemented carbide material, the number of pores (first pores) with a circle-equivalent diameter of less than 0.2 μm and the number of pores (second pores) with a circle-equivalent diameter of 0.2 μm or more were measured in a rectangular measurement field of view of 24.9 μm × 18.8 μm. The specific measurement method is described in embodiment 1, and therefore the description thereof will not be repeated. The results are shown in the "Less than 0.2 μm (number)" and "0.2 μm or more (number)" columns of "Number of pores" for "Cemented carbide material" in Table 2.

[0118] <Rotary tools> The average particle size of the tungsten carbide particles, the number of pores, and the composition of the cemented carbide of each sample rotary tool were measured.

[0119] <Average particle size of tungsten carbide particles> The average particle size of tungsten carbide particles was measured for the cemented carbide of each sample rotary tool. The specific measurement method is described in embodiment 2, so the description will not be repeated. The results are shown in the "Average particle size (μm)" column of "WC particles" under "Rotary tool" in Table 2.

[0120] Number of pores For the cemented carbide of each sample rotary tool, the number of pores (first pores) with a circle equivalent diameter of less than 0.2 μm and the number of pores (second pores) with a circle equivalent diameter of 0.2 μm or more were measured in three rectangular measurement fields of 24.9 μm × 18.8 μm. The specific measurement method is described in embodiment 2, and therefore the description will not be repeated. Of the numbers of pores in each of the three measurement fields, the largest number of pores is shown in the "Less than 0.2 μm (number)" and "0.2 μm or more (number)" columns of "Number of pores" under "Rotary tool" in Table 2.

[0121] <Composition of cemented carbide> It was confirmed that the composition of the cemented carbide in the rotary tool was the same as the composition of the cemented carbide material before being processed into the rotary tool in all samples.

[0122] <Cutting test> Drill Holes were drilled into commercially available semiconductor printed circuit boards using the small-diameter drills of Samples 1 to 8, Sample 1-1, and Sample 1-2. The drilling conditions were a rotation speed of 200 krpm and a feed rate of 1.0 m / min. Five drills were used for drilling. For each drill, the hole position accuracy was measured every 100 holes drilled. The number of holes drilled when the average value of the five drills + 3σ exceeded 70 μm was counted. The results are shown in the "Tool life" column under "Rotary tool" in Table 2. The greater the number of holes drilled, the longer the tool life.

[0123] <End Mill> The side surfaces of S45C blocks were machined using the end mills of Sample 9 and Sample 1-3. The machining conditions were a rotation speed of 10 krpm, a feed rate of 400 mm / min, a depth of cut (axial direction) ap of 1.5 mm, and a depth of cut (radial direction) ae of 0.2 mm. Three end mills were used for machining. The cutting length was measured when the flank wear amount reached 0.2 mm. The average cutting length for the three end mills is shown in the "Tool life" column under "Rotary tool" in Table 2. The longer the cutting length, the longer the tool life.

[0124] [Table 2]

[0125] <Consideration> The small-diameter drills of Samples 1 to 8 correspond to Examples, and the small-diameter drills of Samples 1-1 and 1-2 correspond to Comparative Examples. It was confirmed that the small-diameter drills of Samples 1 to 8 (Examples) had longer tool life than the small-diameter drills of Samples 1-1 and 1-2 (Comparative Examples).

[0126] The small-diameter drill of sample 1-1 broke before drilling 1,000 holes. The small-diameter drill of sample 1-2 showed localized wear progression starting from small chipping.

[0127] The end mill of Sample 9 corresponds to an example, and the end mills of Samples 1-3 correspond to comparative examples. It was confirmed that the end mill of Sample 9 (example) had a longer tool life than the end mills of Samples 1-3 (comparative examples).

[0128] Although the embodiments and examples of the present disclosure have been described above, it is originally intended that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways. The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims rather than the above-described embodiments and examples, and it is intended to include any modifications within the scope of the claims that are equivalent to the claims. [Explanation of symbols]

[0129] 1. Cemented carbide material 2 Pore 3 Rotary tools 4 grooves P1 rotation axis P2 cutting edge

Claims

1. A cemented carbide material for a rotary tool, The cemented carbide material comprises tungsten carbide particles and a binder phase, The cemented carbide material contains 9 or less pores having a circular equivalent diameter of less than 0.2 μm in one rectangular measurement field of view of 24.9 μm × 18.8 μm, The cemented carbide material for a rotary tool, wherein the measurement field is provided at the center of a cross section of the cemented carbide material.

2. 2. The cemented carbide material for a rotary tool according to claim 1, wherein the tungsten carbide particles have an average particle size of 0.40 μm or more and 1.00 μm or less.

3. 3. The cemented carbide material for a rotary tool according to claim 1, wherein the tungsten carbide particles have an average particle size of 0.40 μm or more and less than 0.80 μm.

4. 4. The cemented carbide material for a rotary tool according to claim 1, wherein the cemented carbide material contains 85.0 vol % to 95.5 vol % of the tungsten carbide particles and 0.5 vol % to 15.0 vol % of the binder phase.

5. A rotary tool made of cemented carbide, The cemented carbide comprises tungsten carbide particles and a binder phase; The cemented carbide includes 9 or less pores having a circle equivalent diameter of less than 0.2 μm in each of a first measurement field, a second measurement field, and a third measurement field, each of the first measurement field, the second measurement field, and the third measurement field is a rectangle of 24.9 μm×18.8 μm; the first measurement field of view is provided on a cross section of the cemented carbide having a normal line parallel to a rotation axis P1 of the rotary tool so as to include the rotation axis P1; the second measurement field of view is provided on the cross section of the cemented carbide so as to include a position P3 on a line segment L connecting the rotation axis P1 and the cutting edge P2 of the rotary tool, the position P3 being 1 / 3 of the length L1 of the line segment L from the rotation axis P1; The third measurement field of view is provided on the cross section of the cemented carbide so as to include a position P4 on the line L and at a distance from the rotation axis P1 that is 2 / 3 of the length L1 of the line L.

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