Coated cutting tools

Abstract

This invention provides a durable coated cutting tool for AlCrSi nitride, which has a high Si content and a fine microstructure. [Solution] A coated cutting tool comprising a base material and a hard coating on the base material. The hard coating consists of a nitride containing 65 to 85 atomic percent of aluminum (Al), 10 to 30 atomic percent of chromium (Cr), and 3 to 15 atomic percent of silicon (Si) relative to the total amount of metals including metalloids, and the atomic ratio (atomic %) A of metal elements including metalloids and nonmetals, when the total amount of metal elements including metalloids and nonmetals is 100 atomic percent, is 1.08.

Description

[Technical Field]

[0001] The present invention relates to a coated cutting tool. [Background Art]

[0002] AlCrSi nitride is a film type excellent in heat resistance and wear resistance, and is applied to coated cutting tools. The applicant of the present application has proposed further increasing the nitrogen content ratio in a hard coating of AlCrSi nitride with a high Si content and a refined structure (Patent Document 1). [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] International Publication No. 2015 / 141743 [Summary of the Invention] [Problems to be Solved by the Invention]

[0004] In recent years, there has been a demand for machining high-hardness work materials with high efficiency and high precision, and it has been confirmed that even conventional AlCrSi nitride with a high Si content and a fine structure still has room for improvement in durability. An object of the present invention is to provide a coated cutting tool excellent in durability for AlCrSi nitride having a high Si content and a fine structure. [Means for Solving the Problems]

[0005] One aspect of the present invention is a coated cutting tool comprising a substrate and a hard coating on the substrate, wherein the hard coating consists of a nitride containing 70 to 90 atomic percent of aluminum (Al), 10 to 30 atomic percent of chromium (Cr), and 3 to 15 atomic percent of silicon (Si) relative to the total amount of metals including metalloids, and the atomic ratio (atomic %) A of metal elements including metalloids and nonmetals, when the total amount of metal elements including metalloids and nonmetals is 100 atomic percent, is 1.08

[0006] Furthermore, in the intensity profile obtained from the limited-field diffraction pattern of the transmission electron microscope, it is preferable that the ratio IH / IF of the maximum peak intensity IF due to the cubic crystal and the maximum peak intensity IH due to the hexagonal crystal is 0.5 or more and 0.9 or less. Furthermore, when observing the surface or cross-section of the hard coating, there may be five or fewer droplets with an equivalent circular diameter of 3 μm or more within a 50 μm × 40 μm area. Furthermore, an intermediate film may be provided between the hard film and the substrate. Furthermore, an upper layer may be provided on top of the hard coating. Furthermore, the upper layer may be a nitride or a carbonitride. Furthermore, the upper layer may be a nitride or carbonitride containing 60 to 95 atomic percent titanium (Ti) and 3 to 40 atomic percent silicon (Si) relative to the total amount of metals including the metalloid. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a coated cutting tool with excellent durability. [Brief explanation of the drawing]

[0008] [Figure 1] ​This is an example of a cross-sectional view (30,000x magnification) of the hard coating according to this embodiment. [Figure 2] This is an example of a cross-sectional view (500,000x magnification) of the hard coating according to this embodiment. [Figure 3] This figure shows the limited field diffraction pattern of the hard coating according to this embodiment. [Figure 4] This figure shows the intensity profile obtained from the limited field diffraction pattern in Figure 3. [Figure 5A] An example of a surface observation photograph (200x magnification) of the coated cutting tool in this embodiment is shown. [Figure 5B] This shows a surface observation (5,000x magnification) of a mirror-finished sample of the coated cutting tool used in this embodiment. [Figure 6A] An example of a surface observation photograph (200x magnification) of a conventional coated cutting tool is shown. [Figure 6B] This shows a surface observation (5,000x magnification) of a mirror-finished sample of a conventional coated cutting tool. [Modes for carrying out the invention]

[0009] The inventors of the present invention discovered that AlCrSi nitrides with a high Si content exhibit excellent durability by controlling the film structure and increasing the Al-Nitrogen content ratio, leading to the present invention. The details of this embodiment will be described below.

[0010] The embodiments of the present invention will be described in detail below. The coated cutting tool of this embodiment is a coated cutting tool having a hard coating made of AlCrSi nitride on the surface of the tool base material.

[0011] In the coated cutting tool of this embodiment, the base material is not particularly limited, but it is preferable to use a WC-Co-based cemented carbide, which has excellent strength and toughness, as the base material.

[0012] Details regarding the component composition, structure, properties, and manufacturing method of the hard coating constituting the coated cutting tool of this embodiment will be described.

[0013] <Component composition: Aluminum (Al), Chromium (Cr), Silicon (Si)> The hard coating according to the present embodiment is a nitride containing aluminum (Al) in an amount of 65 atomic % to 85 atomic %, chromium (Cr) in an amount of 10 atomic % to 30 atomic %, and silicon (Si) in an amount of 4 atomic % to 15 atomic %, based on the total amount of metal elements including metalloids (hereinafter referred to as metal elements). The nitride of AlCrSi is a film type excellent in wear resistance and heat resistance. Al is an element that imparts heat resistance to the hard coating. When the hard coating contains a certain amount of Al, the heat resistance is improved. In addition, an oxide protective film is easily formed on the tool surface, so that tool damage is easily suppressed. Furthermore, the coating structure becomes fine, so that wear of the hard coating caused by welding is easily suppressed. Additionally, cutting resistance tends to decrease. In order to sufficiently exert these effects of Al addition, the hard coating according to the present embodiment contains Al in an amount of 65 atomic % or more. More preferably, Al content is 68 atomic % or more. On the other hand, when Al content is excessively high, hexagonal AlN increases excessively, making the hard coating brittle. Therefore, the hard coating according to the present embodiment contains Al in an amount of 85 atomic % or less. More preferably, Al content is 80 atomic % or less. Even more preferably, Al content is 75 atomic % or less.

[0014] Cr is an element that imparts wear resistance to the hard coating. When the hard coating contains a certain amount of Cr, the wear resistance is improved. The hard coating according to the present embodiment contains Cr in an amount of 10 atomic % or more. More preferably, Cr content is 20 atomic % or more. On the other hand, when Cr content is excessively high, the heat resistance of the hard coating decreases. Therefore, the hard coating according to the present embodiment contains Cr in an amount of 30 atomic % or less. More preferably, Cr content is 25 atomic % or less. In the hard coating according to the present embodiment, the total content of Al and Cr is preferably 85 atomic % or more. More preferably, the total content of Al and Cr is 90 atomic % or more.

[0015] Si is an element that refines the structure of the hard coating. The refinement of the coating structure improves wear resistance and heat resistance. In the hard coating according to the present embodiment, the Si content is 3 atomic % or more. More preferably, the Si content is 5 atomic % or more. On the other hand, when the Si content ratio becomes excessively high, hexagonal AlN increases excessively, which reduces the durability of the coated cutting tool. Therefore, in the hard coating according to the present embodiment, the Si content is 15 atomic % or less. More preferably, the Si content is 12 atomic % or less.

[0016] The content ratio of metal elements in the hard coating according to the present embodiment can be measured using an electron probe microanalyzer (EPMA) on a mirror-finished hard coating. In this case, for example, after mirror-finishing the surface of the hard coating, an analysis range with a diameter of about 1 µm can be analyzed at 5 points, and the content ratio can be obtained from the average of 3 points excluding the maximum value and the minimum value.

[0017] <Atomic ratio A of metal elements and atomic ratio B of nitrogen> In the hard coating according to the present embodiment, when the total of metal elements including metalloids and nonmetallic elements is 100 atomic %, the atomic ratio A of the metal elements including metalloids and the atomic ratio B of nitrogen satisfy the relationship of 1.08 < B / A < 1.30. For the values of atomic ratios A and B, the measurement values obtained by EPMA according to the measurement method described above are used. As nonmetallic elements, in addition to nitrogen, carbon and oxygen may be included as unavoidable impurities. In some cases, Ar may also be included as an unavoidable impurity. When the total of metal elements including metalloids and nonmetallic elements is 100 atomic %, carbon and oxygen contained as unavoidable impurities are each included at 5 atomic % or less. When the B / A value is greater than 1.08, complete nitrides are sufficiently formed at the micro level. The hard coating according to the present embodiment can improve heat resistance by increasing the content ratio of Al and nitrogen. On the other hand, when the B / A value is greater than 1.30, coating fracture tends to occur easily. B / A is preferably greater than 1.10. B / A is preferably less than 1.25, and more preferably less than 1.23. B / A preferably satisfies 1.10 < B / A < 1.25.

[0018] <Crystal structure> The hard coating according to this embodiment exhibits peak intensities attributable to cubic and hexagonal crystals in the intensity profile obtained from the limited-field diffraction pattern of a transmission electron microscope, with the peak intensity attributable to the (200) or (111) plane of the cubic crystals showing the maximum intensity. The inclusion of hexagonal crystals in the coating suppresses grain growth of the dominant cubic crystals, resulting in a finer coating structure. This makes it possible to improve wear resistance by making the coating structure finer while maintaining the durability of the hard coating. The hard coating according to this embodiment is presumed to exhibit excellent durability by increasing the ratio of Al to nitrogen and incorporating hexagonal AlN to refine the coating structure. The intensity profile obtained from the limited-field diffraction pattern is an intensity profile where the horizontal axis is the distance from the center of the (000) plane spot (radius r), and the vertical axis is the integrated intensity over one full circle at each radius r (in arbitrary units). In the intensity profile obtained from the limited-field diffraction pattern, peaks mainly consisting of hexagonal crystals appear in the range of 3 to 4 nm from the center of the (000) spot. In this embodiment, the intensity profile obtained from the limited-field diffraction pattern is evaluated after removing the background.

[0019] In this embodiment, the hard coating preferably has a ratio IH / IF of 0.5 to 0.9 between the maximum peak intensity IF due to the cubic crystal structure and the maximum peak intensity IH due to the hexagonal crystal structure. This ensures that a certain amount of hexagonal AlN is included, which promotes the refinement of the coating structure.

[0020] In this embodiment, the hard coating preferably has a ratio IH / IS of the maximum peak intensity IH due to the hexagonal phase to the sum of the peak intensities IS due to the cubic and hexagonal phases, which is 0.2 or more and 0.4 or less. The sum of the peak intensities IS due to the cubic and hexagonal phases is determined from the sum of the peak intensities that appear in the range of 7.3 nm from the center of the (000) spot. In this embodiment, the hard coating preferably has a ratio IH / If of the maximum peak intensity IH due to the hexagonal crystal structure to the second strongest peak intensity If due to the cubic crystal structure, which is 1.0 or higher.

[0021] Within the limits of satisfying the requirements described above, the hard coating according to this embodiment may contain metallic elements other than Al, Cr, and Si. For example, to improve the wear resistance, heat resistance, and lubricity of the hard coating, it may contain one or more elements selected from groups 4a, 5a, and 6a of the periodic table, and B, Y, and Cu. These elements are commonly added to AlTiN-based and AlCrN-based hard coatings to improve their properties, and as long as the content ratio is not excessive, they will not significantly reduce the durability of the coated cutting tool. When the hard coating according to this embodiment contains metallic elements other than Al, Cr, and Si, the total content ratio is preferably 10 atomic percent or less. Furthermore, it is preferable that it be 5 atomic percent or less.

[0022] In surface or cross-sectional observation of the hard coating according to this embodiment, it is preferable that there are 5 or fewer droplets with an equivalent circle diameter of 3 μm or more within a 50 μm × 40 μm area. More preferably, there are 2 or fewer. In this invention, droplets are deposits on the hard coating caused by molten particles of about 1 to several tens of μm that are ejected from the cathode in the arc ion plating method. AlCrSi nitrides with a high Al content tend to contain many droplets, but the durability of the coated cutting tool is increased by having fewer coarse droplets in the hard coating. Furthermore, in surface or cross-sectional observation of the hard coating according to this embodiment, it is preferable that there is 1 or fewer droplets with an equivalent circle diameter of 5 μm or more within a 50 μm × 40 μm area. More preferably, there are fewer than 1. The durability of the coated cutting tool is increased by having fewer larger droplets. The number of droplets in the hard coating can be determined by observing at 2,000x magnification with an electron microscope, observing at least five fields of view within a 50 μm × 40 μm area, and calculating the average.

[0023] The coated cutting tool of this embodiment may have an intermediate coating between the base material and the hard coating as needed. For example, a nitride, carbonitride, or carbide containing one or more elements selected from titanium (Ti), aluminum (Al), and chromium (Cr) may be provided. Alternatively, a modified layer made of metal bombard may be provided. Furthermore, an upper layer may be provided on top of the hard coating to improve the durability of the coated cutting tool. The upper layer is preferably a nitride or carbonitride. Preferably, the upper layer is a nitride or carbonitride containing 60 to 95 atomic percent of titanium (Ti) and 5 to 40 atomic percent of silicon (Si).

[0024] The hard coating in this embodiment is a physically vapor-deposited coating. In this embodiment, the hard coating is preferably a hard coating applied by the arc ion plating method, which offers excellent adhesion among physically vapor-deposited coatings. Hard coatings with a high Al content tend to generate many droplets. However, by reducing the number of coarse droplets in a hard coating applied by the arc ion plating method, even with a high Al content, the tool performance of the coated cutting tool becomes more stable. In this embodiment, the coated cutting tool is preferably coated using a film deposition apparatus that has permanent magnets arranged on the back and outer circumference of the target, and a cathode equipped with a magnetic field generating coil that generates a magnetic field to push the plasma forward, located in front of the target. Furthermore, it is preferable that the distance from the target surface to the substrate is 250 mm or more. A longer distance from the target surface to the substrate tends to reduce the number of coarse droplets that reach the substrate. The coating temperature is preferably 450°C to 550°C. The negative pressure bias voltage applied to the substrate is preferably -150 to -100V. The furnace pressure is preferably 2 to 8 Pa. The current supplied to the target is preferably 100 to 200 A. The current supplied to the magnetic field generating coil is preferably 3 to 10 A. [Examples]

[0025] <Base material> As the substrate, a 2-flute ball end mill made of cemented carbide having a composition of WC(bal.)-Co(8 mass%)-Cr(0.5 mass%)-VC(0.3 mass%), an average WC grain size of 0.6 µm, and a hardness of 93.9 HRA was prepared.

[0026] <Manufacturing Method> A film formation apparatus of arc ion plating type was used for film formation. This apparatus includes a plurality of cathodes (arc evaporation sources), a vacuum vessel, and a substrate rotation mechanism. The apparatus used for the coatings of the present example and comparative examples includes a cathode provided with permanent magnets arranged on the back surface and outer circumference of a target, and further provided with a magnetic field generating coil that generates a magnetic field for pushing plasma forward in front of the target. Further, the distance from the target surface to the substrate is 400 mm. The inside of the vacuum vessel is evacuated by a vacuum pump, and gas is introduced through a supply port. A bias power supply is connected to the substrate placed in the vacuum vessel, and independently applies a negative bias voltage to the substrate. The substrate rotation mechanism is attached with a work table, a plate-shaped jig on the work table, and a pipe-shaped jig on the plate-shaped jig. The work table rotates at a speed of 3 revolutions per minute, and the plate-shaped jig and the pipe-shaped jig each rotate on their own axis and revolve.

[0027] <Heating and Vacuum Evacuation Step> Each substrate was fixed to a pipe-shaped jig in a vacuum vessel, and a pre-film formation process was performed as follows. First, the inside of the vacuum vessel was set to 5×10 -3 Pa or less by evacuation. Thereafter, heating was performed by a heater installed in the vacuum vessel until the substrate temperature reached 500°C, and vacuum evacuation was performed. Thereby, the substrate temperature was set to 500°C, and the pressure in the vacuum vessel was set to 5×10 -3 Pa or less.

[0028] <Ar Bombardment Step> Thereafter, Ar gas was introduced into the vacuum vessel, and the internal pressure of the vessel was adjusted to 0.50 Pa. Thereafter, a current of 20 A was supplied to the filament electrode, a negative bias voltage of -150 V was applied to the substrate, and Ar bombardment was performed for 60 minutes.

[0029] <Ti Bombardment Step> Thereafter, nitrogen gas was introduced into the vacuum container at 30 sccm, and the internal pressure of the container was adjusted to 0.3 Pa. Then, a current of 90 A was supplied to the metallic Ti target, a negative bias voltage of -800 V was applied to the base material, and Ti bombardment was performed for 15 minutes.

[0030] <Film Formation Step> After Ti bombardment, the gas inside the vacuum container was replaced with nitrogen, and the pressure inside the vacuum container was adjusted to 5 Pa. A current of 100 A was supplied to the AlCrSi target, a current of 8 A was supplied to the magnetic field generating coil, and a bias voltage was applied to the base material to coat a hard nitride film with a film thickness of approximately 2 μm. Subsequently, a current of 150 A was supplied to the Ti75Si25 target, a current of 8 A was supplied to the magnetic field generating coil, and a bias voltage of -50 V was applied to the base material to coat an upper nitride layer with a film thickness of approximately 1 μm. After coating the hard film, droplets on the film surface were removed by barrel treatment.

[0031] For the coating in the conventional example, the distance from the target surface to the base material was 170 mm, and a film forming apparatus equipped with a cathode having permanent magnets disposed on the back surface and outer periphery of the target was used. Other conditions were the same as those for Inventive Example 1.

[0032]

Table 1

[0033] <<Composition Analysis>> The film composition was measured using a wavelength dispersive electron probe microanalysis (WDS-EPMA) attached to an electron probe microanalyzer (JXA-8500F, manufactured by JEOL Ltd.). A ball end mill for physical property evaluation was mirror-finished, with an acceleration voltage of 10 kV and an irradiation current of 5×10 -8 A, an acquisition time of 10 seconds, and measurement was performed at 5 points in an analysis region having a diameter of approximately 1 μm, and the composition was obtained from the average value of these measurements.

[0034] <<TEM Analysis>> Microscopic analysis was performed using a field discharge transmission electron microscope (JEOL JEM-2100F). The limited field diffraction pattern of the hard coating was obtained with an acceleration voltage of 200kV, a limited field area of ​​φ500nm, a camera length of 100cm, and an incident electron concentration of 5.0pA / cm². 2 The analysis was performed under the conditions of (on a fluorescent screen). The central portion of the hard film of AlCrSi nitride in the direction of film thickness growth was analyzed. The brightness of the obtained limited-field diffraction pattern was converted to obtain an intensity profile. Figure 3 shows the limited-field diffraction pattern of the hard film according to this embodiment. Figure 4 shows the intensity profile of the limited-field diffraction pattern obtained from Figure 3. In Figure 4, "1" is the peak intensity corresponding to the crystal plane of the hexagonal crystal, and is the maximum peak intensity IH attributable to the hexagonal crystal. "2" is the peak intensity corresponding to the (111) plane of the cubic crystal, "3" is the peak intensity corresponding to the (200) plane of the cubic crystal, and "4" is the peak intensity corresponding to the (220) plane of the cubic crystal. "5" and "6" are peak intensities corresponding to the crystal planes of the hexagonal crystal. The hexagonal crystals contained in the microstructure were evaluated from these peak intensities. In the example shown in Figure 4, the peak intensity of "3" is the second strongest peak intensity If attributable to the cubic crystal. The analysis results are shown in Table 2.

[0035] [Table 2]

[0036] For all samples, the B / A ratio exceeded 1.0, confirming that they were nitrogen-rich. TEM analysis revealed that Examples 1 and 2 and Comparative Example 1 exhibited peak intensities attributable to the hexagonal crystal structure, while Comparative Example 2 and Conventional Example 1 did not exhibit peak intensities attributable to the hexagonal crystal structure.

[0037] Next, cutting evaluations were performed using these samples. For cutting conditions 1 to 3, evaluations were conducted using a ball end mill with a tool diameter of 1 mm. (Condition 1) Wet processing Tool: 2-flute carbide ball end mill Model number: EPDBEH2010-0.8, ball radius 0.5mm Cutting method: bottom cutting Workpiece material: STAVAX (52HRC) (manufactured by Börer Uddeholm Co., Ltd.) Cutting depth: 0.1 mm axially, 0.3 mm radially Cutting speed: 107m / min Feed rate per blade: 0.03 mm / blade The film peelability was evaluated at the initial stage of cutting (cutting distance 13.3m). (Condition 2) Dry processing Tool: 2-flute carbide ball end mill Model number: EPDBEH2010-0.8, ball radius 0.5mm Cutting method: bottom cutting Work material: VANADIS23 (64HRC) Cutting depth: 0.1 mm axially, 0.3 mm radially Cutting speed: 107m / min Feed rate per blade: 0.03 mm / blade Evaluate the cutting length until tool life is reached. (Condition 3) Dry processing Tool: 2-flute carbide ball end mill Model number: EPDBEH2010-0.8, ball radius 0.5mm Cutting method: bottom cutting Work material: SLD(H)(60HRC) Cutting depth: Axial direction, 0.07 mm; Radial direction, 0.22 mm Cutting speed: 79m / min Feed rate per blade: 0.02 mm / blade Evaluated the maximum wear width at a cutting distance of 38.5m. Evaluation method: After machining, the workpiece was observed using a scanning electron microscope at a magnification of 1,000x. The width of the friction between the tool and the workpiece on the tool flank was measured, and the portion with the largest friction width was defined as the maximum wear width of the flank. The results of the cutting test are shown in Table 3.

[0038] [Table 3]

[0039] Figure 1 shows a cross-sectional image (30,000x magnification) of the hard coating according to this embodiment, obtained by electron microscope. It can be seen that the hard coating according to this embodiment is refined to the extent that the grain boundaries are not clearly visible. Figure 2 shows a cross-sectional image (500,000x magnification) of the hard coating according to this embodiment, obtained by observing at a higher magnification. Cross-sectional observation by TEM confirmed that the average width of the columnar particles is about 20 nm. This embodiment exhibits a certain amount of peak intensity due to hexagonal crystal planes, which is presumed to have resulted in refined film structure. Because this embodiment contains a high amount of Al and nitrogen, and has a fine structure, it is presumed to have superior durability compared to comparative examples and conventional examples.

[0040] Next, under cutting condition 4, Example 1 and Comparative Example 2 were evaluated using a ball end mill with a tool diameter of 0.3 mm. (Condition 4) Dry processing Tool: 2-flute carbide ball end mill Model number: EPDBEH2003-0.25, ball radius 0.15mm Cutting method: Pocket machining Work material: VANADIS23 (64HRC) Cutting depth: Axial direction, 0.013 mm; Radial direction, 0.013 mm Cutting speed: 38m / min Feed rate per blade: 0.0405 mm / blade Evaluate the maximum wear width at a cutting distance of 2m. Evaluation method: After machining, the workpiece was observed using a scanning electron microscope at a magnification of 1000x. The width of the friction between the tool and the workpiece on the tool flank was measured, and the portion with the largest friction width was defined as the maximum wear width of the flank. The results of the cutting test are shown in Table 4.

[0041] [Table 4]

[0042] Even in small-diameter end mills with a tool diameter of 0.3 mm, this embodiment, which includes hexagonal crystals, was found to have superior durability compared to the comparative example consisting only of cubic crystals. This embodiment is presumed to have excellent durability because it is rich in Al and nitrogen and has a fine structure.

[0043] Figures 5A and 5B show examples of surface observation photographs of the coated cutting tool of this embodiment. Figures 6A and 6B show examples of surface observation photographs of a conventional coated cutting tool. Both are observation photographs taken before the droplets were removed by barrel treatment. Even with barrel treatment, droplets contained within the hard coating cannot be removed. Furthermore, even with barrel treatment, areas where large droplets have fallen off form large depressions. This embodiment (Figures 5A and 5B) is confirmed to have fewer coarse droplets despite being Al-rich compared to the conventional example (Figures 6A and 6B). Therefore, it is estimated that it tends to have superior durability compared to the conventional example in small-diameter end mills with a tool diameter of 1 mm or less.

Claims

1. A coated cutting tool comprising a base material and a hard coating on the base material, The hard coating is made of a nitride containing 65 to 85 atomic percent of aluminum (Al), 10 to 30 atomic percent of chromium (Cr), and 3 to 15 atomic percent of silicon (Si) relative to the total amount of metals including metalloids, and satisfies the relationship 1.08 < B / A < 1.30 between the atomic ratio (atomic %) A of metal elements including metalloids and nonmetal elements, and the atomic ratio (atomic %) B of nitrogen, when the total amount of metal elements including metalloids and nonmetals is 100 atomic percent, and the intensity profile obtained from the limited field diffraction pattern of a transmission electron microscope has peak intensities due to cubic and hexagonal crystals, with the peak intensity due to the (200) plane or (111) plane of the cubic crystal showing the maximum intensity.

2. The coated cutting tool according to claim 1, characterized in that, in the intensity profile obtained from the limited field diffraction pattern of the transmission electron microscope, the ratio IH / IF of the maximum peak intensity IF due to the cubic crystal and the maximum peak intensity IH due to the hexagonal crystal is 0.5 or more and 0.9 or less.

3. The coated cutting tool according to claim 1, wherein, in surface or cross-sectional observation of the hard coating, there are five or fewer droplets with an equivalent circular diameter of 3 μm or more within a range of 50 μm × 40 μm.

4. The coated cutting tool according to claim 1, characterized in that an intermediate coating is provided between the hard coating and the substrate.

5. The coated cutting tool according to claim 1, characterized in that an upper layer is provided on the hard coating.

6. The coated cutting tool according to claim 5, characterized in that the upper layer is a nitride or carbonitride.

7. The coated cutting tool according to claim 6, characterized in that the upper layer is a nitride or carbonitride containing 60 atomic% to 95 atomic% titanium (Ti) and 5 atomic% to 40 atomic% silicon (Si) with respect to the total amount of metals including metalloids.

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