Coated cutting tool

Abstract

This coated cutting tool comprises a base material and a hard film on the base material. The hard film is composed of a nitride containing aluminum (Al) in an amount of 65 to 85 atom% inclusive, chromium (Cr) in an amount of 10 to 30 atom% inclusive, and silicon (Si) in an amount of 3 to 15 atom% inclusive with respect to the total amount of metals including semimetals. The atomic ratio (atom%) A of the metal elements including semimetals and the atomic ratio (atom%) B of nitrogen when the total of metal elements including semimetals and non-metal elements is 100 atom%, satisfy the relationship of 1.08 < B / A < 1.30. In an intensity profile obtainable from a selected area diffraction pattern of a transmission electron microscope, the intensity profile has peak intensities attributed to cubic crystals and hexagonal crystals, and a peak intensity attributed to a (200) plane or (111) plane of the cubic crystals exhibits maximum intensity.

Description

Coated cutting tool

[0001] The present invention relates to a coated cutting tool. The present application claims priority based on Japanese Patent Application No. 2025-029431 filed in Japan on February 26, 2025, the content of which is incorporated herein by reference.

[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 for a hard coating of AlCrSi nitride having a high Si content and a refined structure (Patent Document 1).

[0003] International Publication No. 2015 / 141743

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

[0005] One aspect of the present invention is a coated cutting tool comprising a base material and a hard coating provided on the base material, wherein the hard coating is made of a nitride containing, based on the total amount of metals including metalloids, 70 atomic% or more and 90 atomic% or less of aluminum (Al), 10 atomic% or more and 30 atomic% or less of chromium (Cr), and 3 atomic% or more and 15 atomic% or less of silicon (Si), and when the total of metal elements including metalloids and non-metal elements is 100 atomic%, the atomic ratio (atomic%) A of the metal elements including metalloids and the atomic ratio (atomic%) B of nitrogen satisfy the relationship of 1.08 < B / A < 1.30, and in an intensity profile obtained from a selected area diffraction pattern of a transmission electron microscope, the coated cutting tool has peak intensities derived from cubic crystal and hexagonal crystal, and the peak intensity derived from the (200) plane or (111) plane of the cubic crystal exhibits the maximum intensity.

[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. Also, in surface or cross-sectional observation of the hard coating, there may be 5 or fewer droplets with an equivalent circle diameter of 3 μm or more within a range of 50 μm × 40 μm. Furthermore, an intermediate film may be provided between the hard coating and the substrate. Furthermore, an upper layer may be provided on the hard coating. Furthermore, the upper layer may be a nitride or carbonitride. Furthermore, the upper layer may be a nitride or carbonitride containing 60 atomic% to 95 atomic% titanium (Ti) and 3 atomic% to 40 atomic% silicon (Si) with respect to the total amount of metal including the metalloid.

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

[0008] This is an example of a cross-sectional observation photograph (30,000x magnification) of the hard coating according to this embodiment. This is an example of a cross-sectional observation photograph (500,000x magnification) of the hard coating according to this embodiment. This figure shows the limited field diffraction pattern of the hard coating according to this embodiment. This figure shows the intensity profile obtained from the limited field diffraction pattern in Figure 3. This shows an example of a surface observation photograph (200x magnification) of the coated cutting tool according to this embodiment. This shows a surface observation (5,000x magnification) of a mirror-finished sample of the coated cutting tool according to this embodiment. This shows an example of a surface observation photograph (200x magnification) of a conventional coated cutting tool. This shows a surface observation (5,000x magnification) of a mirror-finished sample of a conventional coated cutting tool.

[0009] The inventors of the present invention have arrived at this invention by discovering that AlCrSi nitrides with a high Si content exhibit excellent durability by controlling the film structure and increasing the ratio of Al to nitrogen. The details of this embodiment will be described below.

[0010] The embodiments of the present invention will now be described in detail. 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 this embodiment consists of a nitride containing 65 to 85 atomic percent of aluminum (Al), 10 to 30 atomic percent of chromium (Cr), and 4 to 15 atomic percent of silicon (Si) relative to the total amount of metal elements including metalloids (hereinafter referred to as metal elements). AlCrSi nitride is a film type with excellent wear resistance and heat resistance. Al is an element that imparts heat resistance to the hard coating. The heat resistance of the hard coating is enhanced by the inclusion of a certain amount of Al. In addition, an oxide protective film is more easily formed on the tool surface, making it easier to suppress tool damage. Furthermore, the film structure becomes finer, making it easier to suppress wear of the hard coating due to welding. In addition, there is a tendency for cutting resistance to decrease. In order to fully exhibit these effects of adding Al, the hard coating according to this embodiment contains 65 atomic percent or more of Al. Furthermore, it is preferable that the Al content be 68 atomic percent or more. On the other hand, if the amount of Al becomes too high, the hexagonal AlN increases excessively, making the hard coating brittle. Therefore, the hard coating according to this embodiment contains 85 atomic percent or less of Al. Furthermore, it is preferable that the amount of Al be 80 atomic percent or less. Even more preferably, it is preferable that the amount of Al be 75 atomic percent or less.

[0014] Cr is an element that imparts wear resistance to hard coatings. The wear resistance of a hard coating is enhanced by the inclusion of a certain amount of Cr. In the hard coating according to this embodiment, the Cr content is 10 atomic percent or more. Furthermore, it is preferable that the Cr content is 20 atomic percent or more. On the other hand, if the Cr content is too high, the heat resistance of the hard coating decreases. Therefore, in the hard coating according to this embodiment, the Cr content is 30 atomic percent or less. Furthermore, it is preferable that the Cr content is 25 atomic percent or less. In the hard coating according to this embodiment, it is preferable that the total of Al and Cr is 85 atomic percent or more. Furthermore, it is preferable that the total of Al and Cr is 90 atomic percent or more.

[0015] Si is an element that refines the structure of the hard coating. Refining the structure of the coating improves wear resistance and heat resistance. The hard coating according to this embodiment contains 3 atomic percent or more of Si. Furthermore, it is preferable that the Si content is 5 atomic percent or more. On the other hand, if the Si content is too high, the hexagonal AlN increases too much, reducing the durability of the coated cutting tool. Therefore, the hard coating according to this embodiment contains 15 atomic percent or less of Si. Furthermore, it is preferable that the Si content is 12 atomic percent or less.

[0016] The content ratio of metallic elements in the hard coating according to this 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, five points are analyzed within an analysis range of approximately 1 μm in diameter, and the ratio can be determined from the average of the three points excluding the maximum and minimum values.

[0017] <Atomic ratio A of metal elements and atomic ratio B of nitrogen> In the hard film according to this embodiment, the atomic ratio A of metal elements including metalloids and the atomic ratio B of nitrogen satisfy the relationship 1.08 < B / A < 1.30 when the total of metal elements including metalloids and nonmetal elements is set to 100 atomic percent. The values ​​of atomic ratios A and B are measured using EPMA values ​​obtained by the measurement method described above. In addition to nitrogen, carbon and oxygen may be included as unavoidable impurities in the nonmetal elements. Ar may also be included as an unavoidable impurity. The carbon and oxygen included as unavoidable impurities are each present at 5 atomic percent or less when the total of metal elements including metalloids and nonmetal elements is set to 100 atomic percent. When the B / A value is greater than 1.08, a complete nitride is sufficiently formed at the micro level. The heat resistance of the hard film according to this embodiment can be improved by increasing the content ratio of Al and nitrogen. On the other hand, when the B / A value is greater than 1.30, film fracture becomes more likely. It is preferable that B / A is greater than 1.10. B / A is preferably less than 1.25, and more preferably less than 1.23. B / A is preferably 1.10 < B / A < 1.25.

[0018] <Crystal Structure> In the intensity profile obtained from the limited-field diffraction pattern of a transmission electron microscope, the hard coating according to this embodiment has peak intensities due to cubic and hexagonal crystals, with the peak intensity due to the (200) or (111) plane of the cubic crystal showing the maximum intensity. By including hexagonal crystals in the coating, the grain growth of the main cubic crystals is suppressed, 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. It is presumed that the hard coating according to this embodiment exhibits excellent durability by increasing the content ratio of Al and nitrogen and including hexagonal AlN to refine the coating structure. The intensity profile obtained from the limited-field diffraction pattern is an intensity profile with the horizontal axis being the distance from the center of the (000) plane spot (radius r) and the vertical axis being the integrated intensity over one full circle at each radius r (arbitrary unit). In the intensity profile obtained from the limited-field diffraction pattern, the peak mainly composed of hexagonal crystals appears 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 phase to the second strongest peak intensity If due to the cubic phase, which is 1.0 or more.

[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, 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, less 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 five or more fields of view within a 50 μm × 40 μm area using an electron microscope at a magnification of 2,000x and taking 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. The hard coating in this embodiment 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 an arc ion plating hard coating with a high Al content, the tool performance of the coated cutting tool becomes more stable. The coated cutting tool in this embodiment is preferably coated using a deposition apparatus equipped with permanent magnets on the back and outer circumference of the target, and a cathode with a magnetic field generating coil in front of the target to generate a magnetic field for pushing the plasma forward. Furthermore, the distance from the target surface to the substrate is preferably 250 mm or more. A longer distance from the target surface to the substrate tends to reduce the number of coarse droplets reaching 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 -100 V. 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.

[0025] <Base Material> The base material prepared was a two-flute ball end mill made of cemented carbide with 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.

[0026] <Manufacturing Method> An arc ion plating type deposition apparatus was used for film deposition. This apparatus includes multiple cathodes (arc evaporation sources), a vacuum chamber, and a substrate rotation mechanism. The apparatus used for coating in this embodiment and comparative example has permanent magnets arranged on the back and outer circumference of the target, and a cathode equipped with a magnetic field generating coil in front of the target to generate a magnetic field for pushing the plasma forward. The distance from the target surface to the substrate is 400 mm. The inside of the vacuum chamber is evacuated by a vacuum pump, and gas is introduced from a supply port. A bias power supply is connected to the substrate placed inside the vacuum chamber, and a negative bias voltage is independently applied to the substrate. The substrate rotation mechanism has a work table, a plate-shaped jig on the work table, and a pipe-shaped jig on the plate-shaped jig attached to it. The work table rotates at a speed of 3 revolutions per minute, and the plate-shaped jig and pipe-shaped jig rotate on their own axis and on their other axis.

[0027] <Heating and Vacuum Exhaust Process> The substrates were each fixed to pipe-shaped jigs inside the vacuum chamber, and the pre-film deposition process was carried out as follows. First, the inside of the vacuum chamber was heated to 5 × 10 －３ The vacuum was evacuated to below Pa. Then, the substrate was heated to 500°C using a heater installed inside the vacuum chamber, and the vacuum was evacuated again. As a result, the substrate temperature was 500°C and the pressure inside the vacuum chamber was 5 × 10⁻⁶. －３ It was set to be less than or equal to Pa.

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

[0029] <Ti Bombardment Process> Subsequently, nitrogen gas was introduced into the vacuum chamber at 30 sccm to set the internal pressure of the chamber to 0.3 Pa. Then, a current of 90 A was supplied to the metal Ti target, and a negative pressure bias voltage of -800 V was applied to the substrate, and Ti bombardment was performed for 15 minutes.

[0030] <Film Formation Process> After Ti bombardment, the gas in the vacuum chamber was replaced with nitrogen, and the pressure inside the vacuum chamber was set 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 substrate to coat it with a hard nitride film with a 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 substrate to coat it with an upper layer of nitride with a thickness of approximately 1 μm. After coating with the hard film, droplets on the film surface were removed by barrel treatment.

[0031] In the conventional coating example, the distance from the target surface to the substrate was 170 mm, and a film deposition apparatus equipped with a cathode having permanent magnets on the back and outer circumference of the target was used. Other conditions were the same as in Example 1 of the present invention.

[0032]

[0033] ≪Composition Analysis≫ The film composition was measured using the wavelength-dispersive electron probe microanalysis (WDS-EPMA) attached to the electron probe microanalyzer (JXA-8500F, manufactured by JEOL Ltd). A ball end mill used for physical property evaluation was mirror-finished, and the accelerating voltage was 10 kV and the irradiation current was 5 × 10⁻¹⁰ －８ A. The acquisition time was set to 10 seconds, and measurements were taken at 5 points within an analysis area with a diameter of approximately 1 μm. The average value was then used to determine the result.

[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 200 kV, a limited field area of ​​φ500 nm, a camera length of 100 cm, and an incident electron concentration of 5.0 pA / cm². ２The 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]

[0036] For all samples, the B / A ratio exceeded 1.0, confirming that they were nitrogen-rich. From the TEM analysis results, it was confirmed that Examples 1 and 2 and Comparative Example 1 had peak intensities due to the hexagonal crystal structure, while Comparative Example 2 and Conventional Example 1 did not have peak intensities due to the hexagonal crystal structure.

[0037] Next, cutting performance 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 machining tool: 2-flute carbide ball end mill, model number: EPDBEH2010-0.8, ball radius 0.5 mm Cutting method: Bottom cutting Workpiece material: STAVAX (52 HRC) (manufactured by Börler Uddeholm GmbH) Depth of cut: Axial, 0.1 mm, radial, 0.3 mm Cutting speed: 107 m / min Feed per tooth: 0.03 mm / tooth Evaluated film peelability at the beginning of cutting (cutting distance 13.3 m) (Condition 2) Dry machining tool: 2-flute carbide ball end mill, model number: EPDBEH2010-0.8, ball radius 0.5 mm Cutting method: Bottom cutting Workpiece material: VANADIS23 (64 HRC) Depth of cut: Axial, 0.1 mm, radial, 0.3 mm Cutting speed: 107 m / min Feed rate per tooth: 0.03 mm / Evaluate the cutting length until tool life (Condition 3) Dry cutting tool: 2-flute carbide ball end mill Model number: EPDBEH2010-0.8, ball radius 0.5 mm Cutting method: Bottom cutting Workpiece material: SLD(H) (60 HRC) Depth of cut: Axial, 0.07 mm, radial, 0.22 mm Cutting speed: 79 m / min Feed rate per tooth: 0.02 mm / Evaluate the maximum wear width at a cutting distance of 38.5 m Evaluation method: After cutting, the workpiece was observed at a magnification of 1,000x using a scanning electron microscope, and the width of the friction between the tool and the workpiece on the tool flank surface was measured. The portion with the largest friction width was defined as the maximum wear width of the flank surface. The cutting test results are shown in Table 3.

[0038]

[0039] Fig. 1 shows a cross-sectional observation photograph (×30,000 magnification) of the hard coating according to the present example taken with an electron microscope. It is confirmed that the hard coating according to the present example is refined to such an extent that crystal grain boundaries cannot be clearly identified. Fig. 2 shows a cross-sectional observation photograph (×500,000 magnification) of the hard coating according to the present example observed at a higher magnification. Cross-sectional observation by TEM confirmed that the average width of the columnar particles was about 20 nm. The present example has a certain amount of peak intensity derived from the hexagonal crystal plane, which is presumed to have resulted in the refinement of the coating structure. The present example contains large amounts of Al and nitrogen and has a fine structure, so it is presumed that durability is superior to that of comparative examples and conventional examples.

[0040] Subsequently, under cutting condition 4, the present 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 cemented carbide ball end mill Model number: EPDBEH2003-0.25, ball radius 0.15 mm Cutting method: Pocket machining Work material: VANADIS23 (64HRC) Depth of cut: Axial direction, 0.013 mm, radial direction, 0.013 mm Cutting speed: 38 m / min Feed per flute: 0.0405 mm / flute The maximum wear width at a cutting distance of 2 m was evaluated. Evaluation method: After cutting, observation was performed at a magnification of 1000 times using a scanning electron microscope, the width of abrasion between the tool and the workpiece on the tool flank was measured, and the portion with the largest abrasion width was defined as the maximum flank wear width. The cutting test results are shown in Table 4.

[0041]

[0042] It was confirmed that even in a small-diameter end mill with a tool diameter of 0.3 mm, the present example containing hexagonal crystals has superior durability compared to the comparative example consisting only of cubic crystals. The present example contains large amounts of Al and nitrogen and has a fine structure, so it is presumed that durability is excellent.

[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 before droplet removal 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. It can be confirmed that this embodiment (Figures 5A and 5B) has fewer coarse droplets despite being Al-rich compared to the conventional example (Figures 6A and 6B). Therefore, it is estimated that for small-diameter end mills with a tool diameter of 1 mm or less, the durability tends to be superior to that of the conventional example.

Claims

1. A coated cutting tool comprising a base material and a hard coating on the base material, wherein the hard coating consists of a nitride containing 65 atomic% to 85 atomic% of aluminum (Al), 10 atomic% to 30 atomic% of chromium (Cr), and 3 atomic% to 15 atomic% of silicon (Si) with respect 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%, satisfies the relationship 1.08 < B / A < 1.30, and the intensity profile obtained from the limited field diffraction pattern of a transmission electron microscope has peak intensities attributable to cubic and hexagonal crystals, with the peak intensity attributable 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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