Hard alloy, coated tool and cutting tool

Abstract

A non-limited cemented carbide of the present invention is a cemented carbide containing W, C and an iron group metal. The ratio of the average Vickers hardness at 1073 K to the average Vickers hardness at 303 K is 0.4 or more.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of Japanese Patent Application No. 2023 - 031681 filed on March 2, 2023, and the entire disclosure of the previous application is incorporated herein by reference. Technical field

[0003] The present invention relates to cemented carbide, coated cutting tools, and cutting tools. Background art

[0004] Cemented carbide containing WC (tungsten carbide), etc. is used for substrates in coated cutting tools and the like, and is utilized in cutting tools and the like. Such cemented carbide requires abrasion resistance, etc.

[0005] As cemented carbide with excellent abrasion resistance, etc., for example, the cemented carbide (super - hard sintered body) described in International Publication No. 2018 / 003877 (Patent Document 1) is known. The cemented carbide described in Patent Document 1 has a Vickers hardness of 1600 - 2600 HV at room temperature and a Vickers hardness of 1500 - 2500 HV at 900 °C. Summary of the invention

[0006] A non - limiting cemented carbide of the present invention is a cemented carbide containing W, C, and iron - group metals. The ratio of the average Vickers hardness at 1073 K to the average Vickers hardness at 303 K is 0.4 or more. Description of the drawings

[0007] Figure 1 It is a perspective view showing a non - limiting cemented carbide (coated cutting tool) of the present invention.

[0008] Figure 2 It is a cross - sectional view near the surface of a non - limiting coated cutting tool of the present invention.

[0009] Figure 3 It is a cross - sectional view near the surface of a non - limiting coated cutting tool of the present invention.

[0010] Figure 4 It is a perspective view showing a non - limiting cutting tool of the present invention. Detailed description of the invention

[0011] <Cemented carbide>

[0012] Hereinafter, a non-limiting cemented carbide 1 of the present invention will be described in detail with reference to the accompanying drawings. However, in each of the drawings referred to below, for the sake of convenience of explanation, only the main components necessary for explaining the embodiments are shown in a simplified manner. Therefore, the cemented carbide 1 may have any structural components not shown in the respective drawings. In addition, the dimensions of the components in each drawing do not faithfully represent the dimensions of the actual structural components and the dimensional ratios of the respective components, etc.

[0013] Figures 1 to 3 The non-limiting example of the cemented carbide 1 shown may contain W (tungsten), C (carbon), and iron group metals.

[0014] In the cemented carbide 1, the ratio of the average Vickers hardness at 1073 K (800 °C) to the average Vickers hardness at 303 K (30 °C) may be 0.4 or more. In other words, the ratio (average Vickers hardness at 1073 K / average Vickers hardness at 303 K) may be 0.4 or more.

[0015] The high-temperature hardness, that is, the Vickers hardness (Hv) at high temperatures, depends to a large extent on the amount of iron group metals such as cobalt (Co). Iron group metals are soft metals, and if the amount of such iron group metals is large, there is a tendency to soften easily at high temperatures.

[0016] In the cemented carbide 1, when the above ratio is 0.4 or more, even if the amount of iron group metals is large, the Vickers hardness at high temperatures can still be maintained at a high level. In other words, compared with the proportion of the amount of iron group metals, the high-temperature hardness is high. Since the high-temperature hardness is high, the wear resistance is high. In addition, since the amount of iron group metals is large, the toughness is easily improved and the chipping resistance is also high. Therefore, the cemented carbide 1 has high wear resistance and chipping resistance. According to the cemented carbide 1, high wear resistance and high chipping resistance can be achieved simultaneously.

[0017] Furthermore, the so-called high temperature may mean 873 to 1073 K (600 to 800 °C). In addition, 303 K (30 °C) is the temperature equivalent to room temperature.

[0018] The average Vickers hardness may be a value measured according to JIS Z 2244:2009. The specific measurement conditions for the average Vickers hardness can be set, for example, as follows.

[0019] Measuring device: "QM-2" manufactured by Nikon Corporation

[0020] Indentation strength: 1000 gf

[0021] Atmosphere: argon (Ar)

[0022] Measuring temperature: 303 K (30 °C), 1073 K (800 °C)

[0023] Measurement number: 5

[0024] The above ratio can be 0.43 or more. In this case, the abrasion resistance and chipping resistance are likely to be improved.

[0025] Also, the average Vickers hardness at 303K can be 1200 - 1800. Additionally, the average Vickers hardness at 1073K can be 400 - 800. The above ratio can also be 0.4 - 0.5. The above ratio can also be 0.43 - 0.5.

[0026] The product of the above ratio and the amount of iron group metal can be 3 or more. In this case, the abrasion resistance and chipping resistance are likely to be improved.

[0027] The above product can also be 3.74 or more. In this case, the abrasion resistance and chipping resistance are more likely to be improved.

[0028] Also, the amount of iron group metal can be 5 - 15 mass%. Additionally, the above product can also be 3 - 7.5. The above product can also be 3.74 - 7.5.

[0029] Cemented carbide 1 can have a hard phase containing W and C. The hard phase can contain W and C as main components. The so-called "main component" can mean the component with the largest mass% value compared to other components. Specifically, among the components contained in the hard phase, the top 2 in terms of mass% value can be W and C. Also, cemented carbide 1 (hard phase) can contain W and C in the form of WC.

[0030] Examples of the iron group metal include Co and Ni (nickel), etc. The iron group metal can be cobalt.

[0031] Cemented carbide 1 can have a binder phase containing an iron group metal. The binder phase can contain an iron group metal as a main component. The binder phase can function as a phase that bonds adjacent hard phases.

[0032] Cemented carbide 1 can have a β phase. The β phase can be a complex carbide containing at least one of Ti (titanium), Nb (niobium), Ta (tantalum), and Zr (zirconium) and W.

[0033] The amount of the β phase can be 5 - 15 mass%. Additionally, the amount of the β phase can also be 7 - 15 mass%. If the β phase is present in such a relatively large proportion, the above ratio is likely to reach 0.4 or more.

[0034] The composition of the cemented carbide 1, for example, can be measured by Energy Dispersive X-ray Spectroscopy (EDS). The measurement can be carried out using EDS attached to an electron microscope. As the electron microscope, for example, a Scanning Electron Microscopy (SEM) and a Transmission Electron Microscopy (TEM) etc. can be mentioned.

[0035] <Manufacturing method of cemented carbide>

[0036] Next, a non-limiting manufacturing method of a cemented carbide of the present invention will be described.

[0037] First, as raw material powders, WC powder, Co powder, TiC powder, TaC powder, ZrC powder, NbC powder, etc. can be prepared. The proportion of Co powder can be 5 to 15 mass%. In addition, the proportion of TiC powder can be 0.5 to 15 mass%. The proportion of TaC powder can be 0 to 5 mass%. The proportion of ZrC powder can be 0 to 3 mass%. The proportion of NbC powder can be 0 to 5 mass%. The balance can be WC powder.

[0038] The average particle size of the raw material powders can be appropriately selected in the range of 0.1 to 10 μm. The average particle size of the raw material powders can be a value measured by the Microtrac method.

[0039] The prepared raw material powders can be mixed and formed to obtain a formed body. As the forming method, for example, stamping forming, casting forming, extrusion forming, cold isostatic pressing, etc. can be mentioned.

[0040] After dewaxing treatment can be carried out on the obtained formed body, firing can be carried out. The firing can be carried out in a non-oxidizing atmosphere such as a vacuum, an argon atmosphere, and a nitrogen atmosphere. The firing temperature can be 1500 to 1600 °C, and in addition, it can also be 1550 to 1600 °C. If fired at such a high firing temperature, the above ratio is likely to reach 0.4 or more. Also, the firing time can be 0.5 to 3 hours.

[0041] Cooling can be carried out after firing to obtain the cemented carbide.

[0042] In addition, the above manufacturing method is an example of the method for manufacturing cemented carbide. Therefore, the cemented carbide is of course not limited to being made by the above manufacturing method.

[0043] <Coated cutting tool>

[0044] Next, for a non-limiting coated cutting tool 101 of the present invention, taking the case where the above-described cemented carbide 1 is used as an example, it will be described with reference to the drawings.

[0045] The coated cutting tool 101, as Figures 1 to 3 a non-limiting example shown, may have a cemented carbide 1 and a coating 103 on the surface 3 of the cemented carbide 1. The coated cutting tool 101 may have the cemented carbide 1 as a substrate. When the coated cutting tool 101 has the cemented carbide 1, since the cemented carbide 1 has high wear resistance and chipping resistance, it is easy to improve cutting performance such as interrupted cutting performance. Therefore, the durability of the coated cutting tool 101 is high.

[0046] The coating 103 may be located on the entire surface 3 of the cemented carbide 1, or may be located only on a part thereof. That is, the coating 103 may be located on at least a part of the surface 3 of the cemented carbide 1.

[0047] The coating 103 may be formed by Chemical Vapor Deposition (CVD). In other words, the coating 103 may be a CVD film. Also, the coating 103 may be a PVD film formed by Physical Vapor Deposition (PVD).

[0048] The coating 103 may be a single-layer structure, or may be a multi-layer stacked structure. As the composition of the coating 103, for example, TiCN (titanium carbonitride), Al2O3 (aluminum oxide), and TiN (titanium nitride) can be cited.

[0049] The coating 103, as Figure 2 a non-limiting example shown, may successively have a TiCN layer 105 and an Al2O3 layer 107 starting from the cemented carbide 1 side. The TiCN layer 105 may be in contact with the cemented carbide 1. The Al2O3 layer 107 may be in contact with the TiCN layer 105.

[0050] The coating 103, as Figure 3 a non-limiting example shown, may successively have a TiN layer 109, a TiCN layer 105, and an Al2O3 layer 107 starting from the cemented carbide 1 side. The TiN layer 109 may be in contact with the cemented carbide 1. The TiCN layer 105 may be in contact with the TiN layer 109. The Al2O3 layer 107 may be in contact with the TiCN layer 105.

[0051] Coating 103 is not limited to a specific thickness. For example, the average thickness of the TiCN layer 105 can be set to about 1 to 15 μm. The average thickness of the Al2O3 layer 107 can be set to about 1 to 15 μm. The average thickness of the TiN layer 109 can be set to about 0.1 to 5 μm. The thickness of the coating 103 can be measured by cross-sectional observation using an electron microscope. For example, the thickness can be measured at 10 or more measurement points at arbitrary positions of each layer, and the average value can be calculated.

[0052] In Figure 1 it, a cutting insert is shown as a non-limiting example of the coated tool 101. Also, the form of the coated tool 101 is not limited to a cutting insert.

[0053] The coated tool 101 may have: a first face 111 (upper face); a second face 113 (side face) adjacent to the first face 111; and a cutting edge 115 located at the intersection of the first face 111 and the second face 113.

[0054] The first face 111 may be a rake face. The entire first face 111 may be a rake face, or only a part thereof may be a rake face. For example, the region along the cutting edge 115 in the first face 111 may be a rake face.

[0055] The second face 113 may be a flank face. The entire second face 113 may be a flank face, or only a part thereof may be a flank face. For example, the region along the cutting edge 115 in the second face 113 may be a flank face.

[0056] The cutting edge 115 may be located over the entire intersection of the first face 111 and the second face 113, or may be located only at a part of this intersection. The cutting edge 115 can be used for cutting a work material when manufacturing a machined product using the coated tool 101.

[0057] The coated tool 101 may have a through-hole 117. When fixing the coated tool 101 to a tool holder, the through-hole 117 can be used for installing a bolt or a clamping member, etc. The through-hole 117 can be formed from the first face 111 to the face (lower face) on the opposite side of the first face 111, and can be opened in these faces. Also, there is no problem with a structure in which the through-hole 117 opens in regions opposite to each other in the second face 113.

[0058] The coated tool 101 may be a quadrilateral plate shape. Also, the shape of the coated tool 101 is not limited to a quadrilateral plate shape. For example, the first face 111 may also be triangular, pentagonal, hexagonal, or circular.

[0059] The coated cutting tool 101 is not limited to a specific size. For example, the length of one side of the first surface 111 can be set to about 3 to 20 mm. In addition, the height from the first surface 111 to the surface (lower surface) on the opposite side of the first surface 111 can be set to about 5 to 20 mm.

[0060] <Manufacturing Method of Coated Cutting Tool>

[0061] Next, a manufacturing method of a non-limiting coated cutting tool of the present invention will be described.

[0062] A coated cutting tool can be obtained by forming a film on the surface of cemented carbide by CVD method.

[0063] The TiCN layer can be formed as follows. First, as the reaction gas composition, a mixed gas containing titanium tetrachloride (TiCl4) gas at 0.1 to 10% by volume, nitrogen (N2) gas at 10 to 60% by volume, methane (CH4) gas at 0.1 to 15% by volume, and the balance being hydrogen (H2) gas can be adjusted. Then, this mixed gas can be introduced into the furnace chamber, the temperature can be set to 800 to 1100 °C, and the pressure can be set to 5 to 30 kPa to form the TiCN layer.

[0064] The Al2O3 layer can be formed as follows. First, as the reaction gas composition, a mixed gas containing aluminum trichloride (AlCl3) gas at 0.5 to 5% by volume, hydrogen chloride (HCl) gas at 0.5 to 3.5% by volume, carbon dioxide (CO2) gas at 0.5 to 5% by volume, hydrogen sulfide (H2S) gas at 0.5% by volume or less, and the balance being hydrogen (H2) gas can be adjusted. Then, this mixed gas can be introduced into the furnace chamber, the temperature can be set to 930 to 1010 °C, and the pressure can be set to 5 to 10 kPa to form the Al2O3 layer.

[0065] The TiN layer can be formed as follows. First, as the reaction gas composition, a mixed gas containing titanium tetrachloride (TiCl4) gas at 0.1 to 10% by volume, nitrogen (N2) gas at 10 to 60% by volume, and the balance being hydrogen (H2) gas can be adjusted. Then, this mixed gas can be introduced into the furnace chamber, the temperature can be set to 800 to 1010 °C, and the pressure can be set to 10 to 85 kPa to form the TiN layer.

[0066] In addition, the above manufacturing method is an example of a coated cutting tool manufacturing method. Therefore, the coated cutting tool is of course not limited to being manufactured by the above manufacturing method.

[0067] <Cutting Tool>

[0068] Next, taking the case of including the above coated cutting tool 101 as an example, a non-limiting cutting tool 201 of the present invention will be described with reference to the drawings.

[0069] The cutting tool 201, as a non-limiting example shown as follows, may include a tool shank 203 and a coated cutting tool 101. The tool shank 203 may extend from a first end 203a toward a second end 203b. Additionally, a clamping groove 205 may be provided on the side of the first end 203a. The coated cutting tool 101 may be located in the clamping groove 205. When the cutting tool 201 includes the coated cutting tool 101, stable cutting can be performed due to the high durability of the coated cutting tool 101. Figure 4 The clamping groove 205 may be a part for mounting the coated cutting tool 101. The clamping groove 205 may open on the outer peripheral surface of the tool shank 203 and the end surface on the side of the first end 203a.

[0070] The coated cutting tool 101 may be mounted in the clamping groove 205 by a method in which at least a part of the cutting edge 115 protrudes from the tool shank 203. Additionally, the coated cutting tool 101 may be mounted in the clamping groove 205 by bolts 207. That is, the bolts 207 may be inserted into the through holes 117 of the coated cutting tool 101, and the front ends of the bolts 207 may be inserted into the threaded holes formed in the clamping groove 205, and the bolts 207 may be fixed to the threaded holes, whereby the coated cutting tool 101 is mounted in the clamping groove 205. At this time, the lower surface of the coated cutting tool 101 may be in direct contact with the clamping groove 205, or a spacer may be interposed between the coated cutting tool 101 and the clamping groove 205.

[0071] As the material of the tool shank 203, for example, steel and cast iron can be cited. When the material of the tool shank 203 is steel, the tool shank 203 has high toughness.

[0072] In one example shown as follows, a cutting tool 201 for so-called turning is illustrated. As turning, for example, internal diameter machining, external diameter machining, and grooving can be cited. Additionally, the cutting tool 201 (coated cutting tool 101) is not limited to the use for turning. For example, there is no problem in using the coated cutting tool 101 for a cutting tool 201 used for milling.

[0073] Figure 4 In the above non-limiting embodiments, an example in which the coated cutting tool 101 and the cutting tool 201 use cemented carbide 1 is described, but the cemented carbide 1 can also be applied to other uses. As other uses, for example, wear-resistant parts such as sliding parts or molds, tools such as excavation tools and cutting tools, and impact-resistant parts can be cited.

[0074] As mentioned above, a non-limiting example of a cemented carbide 1, a coated cutting tool 101, and a cutting tool 201 of the present invention is illustrated, but the present invention is not limited to the above-described embodiments, and any natural embodiment can be adopted as long as it does not deviate from the gist of the present invention.

[0075] For example, in the above non-limiting embodiments, an example in which the coated cutting tool 101 and the cutting tool 201 use cemented carbide 1 is described, but the cemented carbide 1 can also be applied to other uses. As other uses, for example, wear-resistant parts such as sliding parts or molds, tools such as excavation tools and cutting tools, and impact-resistant parts can be cited.

[0076] In addition, the cemented carbide 1, the coated cutting tool 101, and the cutting tool 201 may also have the following configurations.

[0077] (1) A cemented carbide containing W, C, and a ferrous metal, wherein the ratio of the average Vickers hardness at 1073 K to the average Vickers hardness at 303 K is 0.4 or more.

[0078] (2) In the cemented carbide of (1) above, the ratio may be 0.43 or more.

[0079] (3) In the cemented carbide of (1) or (2) above, the product of the ratio and the amount of the ferrous metal may be 3 or more.

[0080] (4) In the cemented carbide of (3) above, the product may be 3.74 or more.

[0081] (5) In any one of the cemented carbides of (1) to (4) above, the ferrous metal may be cobalt.

[0082] (6) A coated cutting tool may have: any one of the cemented carbides of (1) to (5) above; a coating on the surface of the cemented carbide.

[0083] (7) In the coated cutting tool of (6) above, the coating may sequentially have a TiCN layer and an Al2O3 layer starting from the cemented carbide side.

[0084] (8) In the coated cutting tool of (6) above, the coating may sequentially have a TiN layer, a TiCN layer, and an Al2O3 layer starting from the cemented carbide side.

[0085] (9) A cutting tool may include: a tool shank extending from a first end toward a second end and having a tool slot on the side of the first end; the coated cutting tool of any one of (6) to (8) above located in the tool slot.

[0086] Hereinafter, examples will be listed to explain the present invention in detail, but the present invention is not limited by the following examples.

[0087] Examples

[0088] [Sample Nos. 1 to 4]

[0089] <Fabrication of Cemented Carbide>

[0090] First, as raw material powders, WC powders with an average particle size of 3 μm, Co powders with an average particle size of 1.5 μm, TiC powders with an average particle size of 1 μm, TaC powders with an average particle size of 1 μm, ZrC powders with an average particle size of 1 μm, and NbC powders with an average particle size of 1 μm were prepared. The average particle size of the raw material powders is the value measured by the Microtrac method.

[0091] Next, the raw material powders were mixed so that the proportions of Co and the β-phase in the sintered body became those shown in Table 1, and were press-formed into a cutting tool shape (CNMG120408) to obtain a green compact. After dewaxing treatment was performed on the obtained green compact, sintering was carried out by maintaining at the sintering temperature shown in Table 1 for 1 hour. Then, after cooling after sintering, the cemented carbide shown in Table 1 was obtained.

[0092] The composition of the obtained cemented carbide was measured by EDS. Specifically, in cross-sectional observation using EDS attached to SEM, measurement was carried out under the conditions of a magnification of 5000 to 20000 times and an average value measured at 5 locations.

[0093] As a result of the EDS measurement, the obtained cemented carbides all contained W, C, and a ferrous metal (Co). More specifically, the obtained cemented carbides all had a hard phase and a binder phase. The hard phase contained W and C as main components, and the binder phase contained a ferrous metal (Co) as a main component. In addition, the obtained cemented carbides all had a β-phase. The composition of the β-phase was measured by EDS, and as a result, the β-phase was (W, Ti, Nb, Ta, Zr)C.

[0094] The average Vickers hardness of the obtained cemented carbide was measured following the method exemplified above. The measurement results are shown in Table 1. Also, the ratio of the average Vickers hardness at 1073K to the average Vickers hardness at 303K is shown in the "Ratio" column of Table 1. In addition, the product of this ratio and the amount of ferrous metal (Co) is shown in the "Product" column of Table 1.

[0095] <Evaluation>

[0096] For the obtained cemented carbide, cutting evaluation was carried out. Specifically, after a TiN layer with an average thickness of 1 μm, a TiCN layer with an average thickness of 10 μm, and an Al2O3 layer with an average thickness of 6 μm were sequentially formed by CVD method from the cemented carbide (substrate) side to obtain a coated tool, cutting evaluation was carried out under the following conditions.

[0097] Machining method: Turning

[0098] Cutting speed: 150 m / min

[0099] Feed rate: 0.4 mm / rev

[0100] Cutting depth: 0.5 mm

[0101] Workpiece material: SCM440 φ200 round bar

[0102] Machining state: WET

[0103] The evaluation results are shown in Table 1. Also, the so-called "number of impacts until the tool tip breaks" in the evaluation results of Table 1 represents the number of impacts until the tool tip breaks during cutting, and can also be called the interrupted cutting performance evaluation.

[0104]

Table 1

[0105]

[0106] Comparing Specimens No. 1 to 3 with Specimen No. 4, the stability is significantly improved.

[0107] Description of Reference Numerals

[0108] 1… Cemented carbide

[0109] 3… Surface

[0110] 101… Coated tool

[0111] 103… Coating

[0112] 105… TiCN layer

[0113] 107… Al2O3 layer

[0114] 109… TiN layer

[0115] 111… First surface (upper surface)

[0116] 113… Second surface (side surface)

[0117] 115… Cutting edge

[0118] 117… Through hole

[0119] 201… Cutting tool

[0120] 203… Tool shank

[0121] 203a… First end

[0122] 203b… Second end

[0123] 205… Groove

[0124] 207… Bolt

Claims

1. A cemented carbide containing W, C and iron group metals, wherein, The ratio of the average Vickers hardness at 1073K to the average Vickers hardness at 303K is 0.4 or more.

2. The cemented carbide according to claim 1, wherein, The ratio is 0.43 or more.

3. The cemented carbide according to claim 1 or 2, wherein The product of the ratio and the amount of the iron group metal is 3 or more.

4. The cemented carbide according to claim 3, wherein, The product is 3.74 or more.

5. The cemented carbide according to any one of claims 1 to 4, wherein, The iron group metal is cobalt.

6. A coated cutting tool, comprising: The cemented carbide according to any one of claims 1 to 5; and A coating located on the surface of the cemented carbide.

7. The coated cutting tool according to claim 6, wherein, The coating sequentially has a TiCN layer and an Al2O3 layer starting from the cemented carbide side.

8. The coated cutting tool according to claim 6, wherein, The coating sequentially has a TiN layer, a TiCN layer and an Al2O3 layer starting from the cemented carbide side.

9. A cutting tool, comprising: A tool shank extending from a first end toward a second end and having a slot on the first end side; and The coated cutting tool according to any one of claims 6 to 8 located in the slot.

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