Carbide alloys, coated tools, and cutting tools

Abstract

A cemented carbide according to a non-limiting aspect of the present disclosure has a hard phase containing W and C, a solid solution phase containing W, C and Ti, and a binding phase containing an iron group metal. The cemented carbide has a surface region extending from the surface of the cemented carbide toward the interior thereof, and an interior region extending from the surface region toward the interior thereof. The difference between the mean Vickers hardness in the surface region and the mean Vickers hardness in the interior region is 1-100 Hv.

Description

Cross-reference to related applications , , , [Figure 2] , [Figure 1] ,

[0006] ,

[0001] This application claims the priority of Japanese Patent Application No. 2023-031682 filed on March 2, 2023, and incorporates the entire disclosure of the previous application herein for reference.

Technical Field

[0002] This disclosure relates to cemented carbide, coated tools, and cutting tools.

Background Art

[0003] Cemented carbide containing WC (tungsten carbide) etc. is used for substrates in coated tools etc. and is utilized in cutting tools etc. Such cemented carbide is required to have chipping resistance etc.

[0004] As a cemented carbide excellent in chipping resistance, for example, the cemented carbide (WC-based cemented carbide substrate) described in JP-A-2022-532 (Patent Document 1) is known. The cemented carbide described in Patent Document 1 has a layered region having no β phase from the surface toward the inside. The difference between the minimum value of the Vickers hardness in this region and the Vickers hardness inside 300 μm away from the surface is 180 to 230 Hv.

Summary of the Invention

[0005] A cemented carbide according to a non-limiting aspect of this disclosure has a hard phase containing W and C, a solid solution phase containing W, C, and Ti, and a binder phase containing a ferrous metal. The cemented carbide has a surface region existing from the surface of the cemented carbide toward the inside, and an internal region existing from the surface region toward the inside. The difference between the average Vickers hardness in the surface region and the average Vickers hardness in the internal region is 1 to 100 Hv.

Brief Description of the Drawings

[0006] [Figure 1] It is a cross-sectional view showing the vicinity of the surface of a cemented carbide according to a non-limiting aspect of this disclosure. [Figure 2]This is a perspective view showing one aspect of a coating tool, not limited to this disclosure. [Figure 3] This is a cross-sectional view showing the vicinity of the surface of one coated tool, not limited to this disclosure. [Figure 4] This is a cross-sectional view showing the vicinity of the surface of one coated tool, not limited to this disclosure. [Figure 5] This is a perspective view showing one aspect of a cutting tool, not limited to this disclosure. [Modes for carrying out the invention]

[0007] <Carbide alloy> Hereinafter, a cemented carbide alloy 1, not limited to this disclosure, will be described in detail with reference to the drawings. However, in the drawings referenced below, for the sake of clarity, only the main components necessary for describing the embodiments are shown in a simplified manner. Therefore, cemented carbide alloy 1 may have any components not shown in the drawings referenced. Furthermore, the dimensions of the components in each drawing do not faithfully represent the dimensions of the actual components or the dimensional ratios of each component.

[0008] In one example, not limited to the one shown in Figure 1, cemented carbide 1 may have a hard phase, a solid solution phase, and a binder phase.

[0009] The hard phase may contain W (tungsten) and C (carbon). The hard phase may contain W and C as its main components. "Main component" may mean the component with the largest mass percentage value compared to other components. Specifically, the top two components in the hard phase in terms of mass percentage value may be W and C. The hard phase may also contain W and C in the form of WC.

[0010] The solid solution phase may contain W, C, and Ti (titanium). The solid solution phase may contain W, C, and Ti as its main components. That is, the sum of the mass percentages of W, C, and Ti in the solid solution phase may be the largest. Also, the top three components in terms of mass percentage among the components contained in the solid solution phase may be W, C, and Ti.

[0011] The binder phase may contain iron group metals. Examples of iron group metals include Co (cobalt) and Ni (nickel). The binder phase may contain at least one of Co and Ni. The binder phase may also contain iron group metals as its main component. Iron group metals, including Co and Ni as examples, may have the largest mass percentage among the components contained in the binder phase. The binder phase can function as a phase that binds adjacent hard phases together.

[0012] The compositions of the hard phase, solid solution phase, and binding phase may be measured, for example, by energy dispersive X-ray spectroscopy (EDS). The measurement may be performed using an EDS attached to an electron microscope. Examples of electron microscopes include scanning electron microscopes (SEM) and transmission electron microscopes (TEM).

[0013] Here, the cemented carbide 1 may have a surface region 3 and an internal region 5, as shown in the example (not limited to) in Figure 1. The surface region 3 may extend inward from the surface 7 of the cemented carbide 1. The internal region 5 may also extend inward from the surface region 3.

[0014] The Vickers hardness (Hv) in surface region 3 and internal region 5 may have the following relationship: The difference between the average Vickers hardness in surface region 3 and the average Vickers hardness in internal region 5 may be between 1 and 100 Hv. In other words, the value calculated from the formula: (average Vickers hardness in surface region) - (average Vickers hardness in internal region) may be between 1 and 100 Hv.

[0015] In this case, the difference in hardness between the surface region 3 and the internal region 5 is relatively small. And, since the above difference is positive, the surface region 3 is slightly harder than the internal region 5, making it easier to improve wear resistance. Also, because the internal region 5 is relatively slightly softer, the impact generated between the internal region 5 and the workpiece during cutting is easily mitigated by the internal region 5, making it easier to improve chipping resistance. Therefore, cemented carbide 1 has high wear resistance and fracture resistance. With cemented carbide 1, it is possible to achieve both high wear resistance and high fracture resistance.

[0016] The above difference may be between 30 and 100 Hv. In this case, wear resistance and fracture resistance tend to improve. The lower limit of the above difference may be, for example, 5 Hv. The upper limit of the above difference may be, for example, 40 Hv.

[0017] The average Vickers hardness in surface region 3 may be between 1350 and 1700 Hv. Alternatively, the average Vickers hardness in surface region 3 may be between 1350 and 1550 Hv. Furthermore, the maximum value of the Vickers hardness across the entire surface region 3 and internal region 5 may be located in surface region 3.

[0018] The average Vickers hardness in internal region 5 may be 1300 to 1650 Hv. Alternatively, the average Vickers hardness in internal region 5 may be 1300 to 1500 Hv. Furthermore, the minimum Vickers hardness value across the entire surface region 3 and internal region 5 may be located in internal region 5.

[0019] The average Vickers hardness may be a value measured in accordance with JIS Z 2244:2009. Specific measurement conditions for the average Vickers hardness may be set, for example, as follows: Measuring device: INNOVATEST Pressing force: 10kgf Atmosphere: Atmosphere Measurement temperature: 25℃ Number of measurements: 3 Others: Grind the cemented carbide obliquely (3° inclination) from the surface to form a polished surface, and use this polished surface as the measurement surface. The grinding is performed with diamond paste.

[0020] The surface region 3 may include the surface 7 of the cemented carbide 1. Also, the internal region 5 may be in contact with the surface region 3.

[0021] The thickness of the surface region 3 may be smaller than the thickness of the internal region 5. For example, the thickness of the surface region 3 may be 1 / 10 or less of the thickness of the internal region 5. The thickness of the surface region 3 may be 2 to 20 μm. The thickness of the internal region 5 may be 50 to 150 μm. The thicknesses of the surface region 3 and the internal region 5 may be measured by cross-sectional observation using an electron microscope.

[0022] The cemented carbide 1 may have a β-phase-depleted layer 9 consisting only of WC and iron-group metals on the surface 7. The β-phase-depleted layer 9 is rich in iron-group metals such as Co and is a layer rich in toughness, and can function as a layer that absorbs the impact generated between the workpiece and the cutting tool during cutting and suppresses chipping.

[0023] The β-phase-depleted layer 9 consisting only of WC and iron-group metals may mean that almost all of the components constituting the β-phase-depleted layer 9 are WC and iron-group metals. Therefore, the β-phase-depleted layer 9 may contain impurities at an inevitable level in the manufacturing process. The total content of the impurities may be 3 mass% or less. In other words, the total value of WC and iron-group metals may be 97 mass% or more. Also, the iron-group metals in the β-phase-depleted layer 9 may have the same composition as the iron-group metals in the binder phase. The β-phase-depleted layer 9 may be confirmed, for example, by EDS.

[0024] The surface region 3 may include the β-phase-depleted layer 9. That is, the surface region 3 may include the β-phase-depleted layer 9 in addition to the hard phase, solid solution phase, and binder phase. In this case, the surface region 3 is likely to be a region with a larger amount of iron-group metals than the internal region 5.

[0025] The total thickness of the surface region 3 including the de-β layer 9 may be greater than the thickness of the de-β layer 9. The de-β layer 9 is not limited to a specific thickness. For example, the thickness of the de-β layer 9 may be 1 to 19 μm. The thickness of the de-β layer 9 may be measured by cross-sectional observation using an electron microscope. Furthermore, the thickness of the de-β layer 9 may be an average value. For example, the thickness may be measured at 10 or more measurement points at arbitrary locations on the de-β layer 9, and the average value may be calculated.

[0026] The iron group metal may be Co. Also, the difference between the average Co content in surface region 3 and the average Co content in internal region 5 may be between -0.1 and -3 mass%. In other words, the value calculated from the formula: (average Co content in surface region) - (average Co content in internal region) may be between -0.1 and -3 mass%. In this case, wear resistance and fracture resistance tend to improve.

[0027] If surface region 3 includes a de-β layer 9, and the total thickness of surface region 3 is greater than the thickness of the de-β layer 9, and the thickness of the de-β layer 9 is 1 to 15 μm, then the difference between the average Co content in surface region 3 and the average Co content in internal region 5 tends to be -0.1 to -3 mass%. Note that the average Co content in surface region 3 may be 5 to 10 mass%. Also, the average Co content in internal region 5 may be 6 to 12 mass%. The average Co content may be the average of measurements taken at 5 locations using EDS. For example, if surface region 3 is 20 μm, the measurement locations may be 3, 7, 11, 15, and 19 μm from the surface 7, and the average of the measurements taken at these 5 locations may be used.

[0028] <Manufacturing method for cemented carbide> Next, a method for manufacturing cemented carbide, not limited to this disclosure, will be described.

[0029] First, raw material powders such as WC powder, Co powder, and TiC powder may be prepared. The proportion of Co powder may be 5 to 12% by mass. The proportion of TiC powder may be 0.5 to 15% by mass. The remainder may be WC powder.

[0030] NbC powder, TaC powder, and ZrC powder may be further prepared as raw material powders. The presence of these raw material powders tends to result in a relatively higher average Vickers hardness in the surface region. The proportion of NbC powder may be 0.1 to 15% by mass. The proportion of TaC powder may also be 0.1 to 15% by mass. The proportion of ZrC powder may also be 0.1 to 15% by mass.

[0031] TiN powder may be further prepared as a raw material powder. By adjusting the proportion of TiN powder, it is easier to control the thickness of the de-β layer. For example, increasing the proportion of TiN powder tends to increase the thickness of the de-β layer. The proportion of TiN powder may be 0 to 0.5% by mass.

[0032] The average particle size of the raw material powder may be appropriately selected within the range of 0.1 to 10 μm. The average particle size of the raw material powder may also be the value measured by the microtrac method.

[0033] The prepared raw material powders may be mixed and molded to obtain a molded body. Examples of molding methods include press molding, slip molding, extrusion molding, and cold isostatic press molding.

[0034] The resulting molded body may be subjected to a binder removal treatment and then fired. The firing may be carried out in a non-oxidizing atmosphere such as a vacuum, argon atmosphere, or nitrogen atmosphere. The firing temperature may be 1450 to 1650°C. A higher firing temperature of 1500 to 1650°C tends to result in a relatively higher average Vickers hardness in the surface region. From the same viewpoint, the firing temperature may be set to 1550 to 1650°C. The firing time may be 0.5 to 3 hours.

[0035] The cemented carbide can be obtained by cooling after firing.

[0036] It should be noted that the above manufacturing method is just one example of a method for producing cemented carbide. Therefore, it goes without saying that cemented carbide is not limited to those produced by the above manufacturing method.

[0037] <Covered Tools> Next, a coated tool 101, not limited to this disclosure, will be described with reference to the drawings, using the case in which it has the above-described cemented carbide 1 as an example.

[0038] The coated tool 101 may have a cemented carbide 1 and a coating layer 103 located on the surface 7 of the cemented carbide 1, as shown in the example (not limited to) in Figures 2 to 4. The coated tool 101 may also have a cemented carbide 1 as its base body. When the coated tool 101 has a cemented carbide 1, the wear resistance and fracture resistance of the cemented carbide 1 are high, which easily improves cutting performance such as intermittent performance. Therefore, the coated tool 101 has high durability.

[0039] The coating layer 103 may be located on the entire surface 7 of the cemented carbide 1, or only on a portion of it. That is, the coating layer 103 may be located on at least a portion of the surface 7 of the cemented carbide 1.

[0040] The coating layer 103 may be formed by chemical vapor deposition (CVD). In other words, the coating layer 103 may be a CVD film. Furthermore, the coating layer 103 may be a PVD film formed by physical vapor deposition (PVD).

[0041] The coating layer 103 may be a single layer or a multi-layered structure. Examples of the composition of the coating layer 103 include TiCN (titanium carbonitride), Al2O3 (alumina), and TiN (titanium nitride).

[0042] The coating layer 103 may have a TiCN layer 105 and an Al2O3 layer 107 in that order from the cemented carbide 1, as shown in the example not limited to Figure 3. 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.

[0043] The coating layer 103 may have, in order from the cemented carbide 1, a TiN layer 109, a TiCN layer 105, and an Al2O3 layer 107, as shown in the example not limited to Figure 4. 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.

[0044] The coating layer 103 is not limited to a specific thickness. For example, the TiCN layer 105 may have an average thickness of approximately 1 to 15 μm. The Al2O3 layer 107 may have an average thickness of approximately 1 to 15 μm. The TiN layer 109 may have an average thickness of approximately 0.1 to 5 μm. The thickness of the coating layer 103 may be measured by cross-sectional observation using an electron microscope. For example, the thickness may be measured at 10 or more measurement points at arbitrary positions in each layer, and the average value may be calculated.

[0045] Figure 2 shows a cutting insert as an example of the coated tool 101, although this is not limited to the coated tool.

[0046] The coating tool 101 may have a first surface 111 (top surface), a second surface 113 (side surface) adjacent to the first surface 111, and a cutting edge 115 located at the intersection of the first surface 111 and the second surface 113.

[0047] The first surface 111 may be a rake face. The entire first surface 111 may be a rake face, or only a part of it may be a rake face. For example, the area of ​​the first surface 111 along the cutting edge 115 may be a rake face.

[0048] The second surface 113 may be a relief surface. The entire second surface 113 may be a relief surface, or only a part of it may be a relief surface. For example, the area of ​​the second surface 113 along the cutting edge 115 may be a relief surface.

[0049] The cutting edge 115 may be located across the entire intersection of the first surface 111 and the second surface 113, or it may be located only in part of this intersection. The cutting edge 115 can be used to cut the workpiece when manufacturing a workpiece using the coated tool 101.

[0050] The coating tool 101 may have a through hole 117. The through hole 117 can be used to attach screws or clamp members when fixing the coating tool 101 to a holder. The through hole 117 may be formed from the first surface 111 to the surface opposite the first surface 111 (the bottom surface), or it may open on these surfaces. There is no problem if the through hole 117 is configured to open in mutually opposing regions on the second surface 113.

[0051] The coating tool 101 may be rectangular in shape. However, the shape of the coating tool 101 is not limited to a rectangular shape. For example, the first surface 111 may be triangular, pentagonal, hexagonal, or circular.

[0052] The coating tool 101 is not limited to a specific size. For example, the length of one side of the first surface 111 may be set to approximately 3 to 20 mm. Also, the height from the first surface 111 to the surface opposite to the first surface 111 (the bottom surface) may be set to approximately 5 to 20 mm.

[0053] <Method for manufacturing covered tools> Next, a method for manufacturing a coating tool, not limited to this disclosure, will be described.

[0054] A coated tool may be obtained by forming a coating layer on the surface of a cemented carbide alloy using the CVD method.

[0055] The TiCN layer may be deposited as follows. First, a mixed gas may be prepared as the reaction gas composition, consisting of 0.1 to 10 volume% titanium tetrachloride (TiCl4) gas, 10 to 60 volume% nitrogen (N2) gas, 0.1 to 15 volume% methane (CH4) gas, and the remainder being hydrogen (H2) gas. Then, this mixed gas may be introduced into a chamber, the temperature may be set to 800 to 1100°C and the pressure to 5 to 30 kPa, and the TiCN layer may be deposited.

[0056] The Al2O3 layer may be formed as follows. First, a mixed gas may be prepared as the reaction gas composition, consisting of 0.5 to 5 volume% aluminum trichloride (AlCl3) gas, 0.5 to 3.5 volume% hydrogen chloride (HCl) gas, 0.5 to 5 volume% carbon dioxide (CO2) gas, 0.5 volume% or less hydrogen sulfide (H2S) gas, and the remainder being hydrogen (H2) gas. Then, this mixed gas may be introduced into a chamber, the temperature may be set to 930 to 1010°C and the pressure to 5 to 10 kPa, and the Al2O3 layer may be formed.

[0057] The TiN layer may be deposited as follows. First, a mixed gas may be prepared as the reaction gas composition, consisting of 0.1 to 10 volume percent titanium tetrachloride (TiCl4) gas, 10 to 60 volume percent nitrogen (N2) gas, and the remainder being hydrogen (H2) gas. Then, this mixed gas may be introduced into a chamber, the temperature may be set to 800 to 1010°C and the pressure to 10 to 85 kPa, and the TiN layer may be deposited.

[0058] It should be noted that the above manufacturing method is just one example of a method for manufacturing coated tools. Therefore, it goes without saying that coated tools are not limited to those manufactured by the above manufacturing method.

[0059] <Cutting tools> Next, a cutting tool 201, not limited to this disclosure, will be described with reference to the drawings, using the case in which it is equipped with the above-described coated tool 101 as an example.

[0060] The cutting tool 201 may include a holder 203 and a coated tool 101, as shown in the example (not limited to) in Figure 5. The holder 203 may extend from a first end 203a to a second end 203b, and may have a pocket 205 on the side of the first end 203a. The coated tool 101 may be located in the pocket 205. When the cutting tool 201 includes a coated tool 101, stable cutting is possible due to the high durability of the coated tool 101.

[0061] The pocket 205 may be the portion into which the covering tool 101 is mounted. The pocket 205 may be open on the outer circumferential surface of the holder 203 and on the end face on the side of the first end 203a.

[0062] The covering tool 101 may be mounted in the pocket 205 such that at least a portion of the cutting edge 115 protrudes from the holder 203. Alternatively, the covering tool 101 may be mounted in the pocket 205 by a screw 207. That is, the covering tool 101 may be mounted in the pocket 205 by inserting the screw 207 into the through hole 117 of the covering tool 101, and then inserting the tip of the screw 207 into a screw hole formed in the pocket 205 and fixing the screw 207 in the screw hole. In this case, the lower surface of the covering tool 101 may be in direct contact with the pocket 205, or a sheet may be sandwiched between the covering tool 101 and the pocket 205.

[0063] Examples of materials for the holder 203 include steel and cast iron. When the holder 203 is made of steel, its toughness is high.

[0064] In the example shown in Figure 5, a cutting tool 201 used in so-called turning operations is illustrated. Examples of turning operations include internal diameter machining, external diameter machining, and grooving. Note that the cutting tool 201 (coated tool 101) is not limited to turning operations. For example, there is no problem in using the coated tool 101 as a cutting tool 201 used in milling operations.

[0065] The above examples illustrate one aspect of the cemented carbide 1, coated tool 101, and cutting tool 201 that are not limited to this disclosure. However, it goes without saying that this disclosure is not limited to the embodiments described above, and can be any embodiment as long as it does not deviate from the gist of this disclosure.

[0066] For example, in the above-described, non-limiting embodiments, the case in which cemented carbide 1 is used for the coated tool 101 and the cutting tool 201 was explained as an example, but cemented carbide 1 can be applied to other applications as well. Other applications include, for example, wear-resistant parts such as sliding parts or molds, tools such as drilling tools and cutting tools, and impact-resistant parts.

[0067] Furthermore, the cemented carbide 1, the coated tool 101, and the cutting tool 201 may have the following configurations. (1) The cemented carbide is a cemented carbide having a hard phase containing W and C, a solid solution phase containing W, C and Ti, and a binder phase containing an iron group metal, wherein the cemented carbide has a surface region extending inward from the surface and an interior region extending inward from the surface region, and the difference between the average Vickers hardness in the surface region and the average Vickers hardness in the interior region is 1 to 100 Hv. (2) The cemented carbide alloy in (1) above may have a difference of 30 to 100 Hv. (3) The cemented carbide described in (1) or (2) above may be cobalt in which the iron group metal is cobalt, and the difference between the average amount of cobalt in the surface region and the average amount of cobalt in the internal region may be -0.1 to -3 mass%. (4) The coated tool may have any one of the cemented carbide alloys described in (1) to (3) above, and a coating layer located on the surface of the cemented carbide alloy. (5) The coated tool described in (4) above may have a coating layer that, in order from the cemented carbide side, consists of a TiCN layer and an Al2O3 layer. (6) The coated tool described in (4) above may have a coating layer that, in order from the cemented carbide side, consists of a TiN layer, a TiCN layer, and an Al2O3 layer. (7) The cutting tool may comprise a holder extending from a first end toward a second end and having a pocket on the side of the first end, and one of the covering tools described in (4) to (6) above, located in the pocket.

[0068] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to the following examples. [Examples]

[0069] [Samples No. 1-5] <Manufacturing of cemented carbide> First, the following raw material powders were prepared: WC powder with an average particle size of 9 μm, Co powder with an average particle size of 1.5 μm, TiC powder with an average particle size of 1.5 μm, NbC powder with an average particle size of 1.1 μm, TaC powder with an average particle size of 0.9 μm, ZrC powder with an average particle size of 1.5 μm, and TiN powder with an average particle size of 1.5 μm. The average particle size of the raw material powders was measured using the microtrac method.

[0070] Next, the raw material powders were mixed in one of the proportions of composition A to E shown in Table 1, and the mixture was press-molded into the shape of a cutting tool (CNMG120408) to obtain a molded body. The obtained molded body was subjected to a binder removal treatment and then fired at the firing temperature shown in Table 2 for 1 hour. After firing, it was cooled to obtain the cemented carbide shown in Table 2.

[0071] The composition of the obtained cemented carbide was measured using EDS. Specifically, cross-sectional observation was performed using an EDS attached to a SEM, with a magnification of 500 to 2000x, and the average value of measurements taken at five locations was used.

[0072] EDS measurements revealed that all obtained cemented carbides contained a hard phase with W and C as the main components, a solid solution phase with W, C, and Ti as the main components, and a binder phase with iron group metal (Co) as the main component. Furthermore, all obtained cemented carbides had a de-β layer on their surface consisting only of WC and iron group metal (Co). The average thickness of the de-β layer is shown in the "De-β Layer Thickness" column of Table 2.

[0073] Each of the obtained cemented carbide alloys has a surface region with a thickness of 20 μm and an interior region with a thickness of 100 μm. The average Vickers hardness in this surface region and interior region was measured according to the method exemplified above. The measurement results are shown in Table 2. The difference between the average Vickers hardness in the surface region and the average Vickers hardness in the interior region is shown in the "Difference" column of "Average Vickers Hardness (Hv)" in Table 2.

[0074] The average Co content in the surface and interior regions was measured according to the method exemplified above. The measurement results are shown in Table 2. The difference between the average Co content in the surface region and the average Co content in the interior region is shown in the "Difference" column of "Average Co Content (mass%)" in Table 2.

[0075] <Rating> The resulting cemented carbide alloy was subjected to cutting evaluation. Specifically, 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 deposited on the cemented carbide (substrate) in that order using the CVD method to create coated tools, and then cutting evaluation was performed under the following conditions.

[0076] Machining method: Turning (Evaluation result 1) Cutting speed: 300m / min Feed rate: 0.3mm / rev Notch: 1.5mm Workpiece material: SCM440 φ200 round bar Processing condition: WET Evaluation item: Check the wear width (mm) at 21 minutes of processing time.

[0077] Machining method: Turning (Evaluation result 2) Cutting speed: 48m / min Feed rate: 0.27mm / rev Notch: 1.0mm Workpiece material: S45C φ200 round bar Processing condition: WET Evaluation item: Check the number of impacts (times) until the blade tip breaks.

[0078] The evaluation results are shown in Table 2. Note that "Number of impacts until cutting edge breakage" in Evaluation Result 2 of Table 2 refers to the number of impacts required for the cutting edge to break during machining, and can also be called intermittent performance evaluation.

[0079] [Table 1]

[0080] [Table 2]

[0081] Samples No. 1-2 and 5 showed improved wear resistance and fracture resistance compared to samples No. 3-4. [Explanation of Symbols]

[0082] 1. Carbide alloy 3...Surface area 5...inner area 7...Surface 9...de-β layer 101... Covered Tools 103...Covering layer 105...TiCN layer 107...Al2O3 layer 109...TiN layer 111...1st surface (top surface) 113...2nd side (side) 115...cutting blade 117... Through hole 201...cutting tools 203...Holder 203a...1st end 203b...2nd end 205... Pocket 207... Screws

Claims

1. A hard phase containing W and C, A solid solution phase containing W, C, and Ti, A cemented carbide having a bonding phase containing iron group metals, The surface region of the cemented carbide that extends from the surface toward the interior, It has an internal region that extends from the surface region toward the interior, The difference between the average Vickers hardness in the surface region and the average Vickers hardness in the internal region is 30 to 100 Hv. The surface has a de-β layer consisting only of WC and iron group metals, The surface region includes the de-β layer, The total thickness of the surface region is greater than the thickness of the de-β layer. The thickness of the de-β layer is 1 to 15 μm. The iron group metal in the bonding phase and the de-β layer is cobalt. A cemented carbide in which the difference between the average cobalt content in the surface region and the average cobalt content in the internal region is -0.1 to -3 mass%.

2. The cemented carbide alloy according to claim 1, A coated tool having a coating layer located on the surface of the cemented carbide.

3. The aforementioned coating layer consists of, in order from the cemented carbide side, a TiCN layer and an Al layer. 2 O 3 A coating tool according to claim 2, having a layer.

4. The coating layer consists of, in order from the cemented carbide side, a TiN layer, a TiCN layer, and an Al layer. 2 O 3 A coating tool according to claim 2, having a layer.

5. A holder extending from a first end toward a second end, with a pocket on the side of the first end, A cutting tool comprising a covering tool according to claim 2, located in the aforementioned pocket.

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