Coated cutting tools

Abstract

The present invention relates to a coated cutting tool having excellent crater resistance on inclined surfaces and chipping resistance on clearance surfaces during cutting operations. A coated cutting tool according to the present invention comprises a base material having an upper surface, a side adjacent to the upper surface, and a cutting edge formed between the upper surface and the side, and a coating layer formed on at least one part of the base material, wherein the base material is made of a cemented carbide comprising 9 to 12 wt% Co, 2 wt% or less of a carbide, carbonitride, or mixture thereof of one or more metals selected from Group 4, Group 5, and Group 6 metals of the periodic table excluding W, and the remainder being WC and unavoidable impurities, and the coating layer comprises an MT-TiCN layer formed on the base material and an α-Al2O3 layer formed on the MT-TiCN layer, wherein the highest priority growth orientation of the α-Al2O3 layer formed on the upper surface of the cutting tool is (0012) and the highest priority growth orientation of the α-Al2O3 layer formed on the side of the cutting tool is (104), and when the Grain Reference Orientation Deviation angle (GROD) of the coating layer is measured by EBSD At that time, it is characterized by the presence of particles in which the internal reference azimuth deviation (GROD) of the entire coating layer is 5% or more.

Description

Technology Field

[0001] The present invention relates to a coated cutting tool capable of suppressing crater wear caused by chemical wear during milling and suppressing breakage of the cutting tool by improving toughness. Background Technology

[0003] When high-speed machining of high-hardness materials, the cutting edge of the cutting tool is exposed to a high-temperature environment of about 1,000°C, and not only does wear occur due to friction and oxidation caused by contact with the workpiece, but it is also subjected to mechanical shock such as intermittent cutting.

[0004] In order to counteract wear caused by such oxidation and mechanical shock, a hard film is formed on the surface of a cemented carbide commonly used as a cutting tool through chemical vapor deposition (hereinafter referred to as 'CVD') or physical vapor deposition (hereinafter referred to as 'PVD').

[0005] These hard films are composed of single or multilayer non-oxide films (e.g., TiN, TiC, TiCN), oxide films (e.g., Al2O3) having excellent oxidation resistance, or a mixture of these. Examples of the non-oxide films include carbides, nitrides, and carbonitrides of metal elements in groups 4, 5, and 6 of the periodic table, such as TiN, TiC, and TiCN, and examples of oxide films include α-Al2O3 or γ-Al2O3.

[0006] Meanwhile, cutting tools differ slightly in their role and required physical properties depending on the surface in contact with the workpiece. For example, the top surface (rake surface) requires oxidation resistance, wear resistance, and anti-adhesion; the cutting edge requires oxidation resistance, thermal crack resistance, and peel resistance; and the side surface (clearance surface) generally requires wear resistance.

[0007] In order to satisfy the different material properties required for each part of such cutting tools to some extent, multi-component thin films containing various elements, multilayer thin films composed of different material layers, or post-processing techniques have been applied, but there is still room for improvement. Prior art literature

[0009] Republic of Korea Published Patent Application No. 2022-0053566 The problem to be solved

[0010] The objective of the present invention is to provide a coated cutting tool that suppresses crater wear caused by chemical wear during milling of a cutting tool having a hard coating layer including an α-Al2O3 layer, and improves toughness to suppress breakage of the cutting tool.

[0011] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0013] To solve the above problem, the present invention provides a cutting tool comprising a base material having an upper surface, a side adjacent to the upper surface, and a cutting edge formed between the upper surface and the side, and a coating layer formed on at least one part of the base material, wherein the base material is made of a cemented carbide comprising 9 to 12 wt% Co, 2 wt% or less of a carbide, carbonitride, or mixture thereof of one or more metals selected from Group 4, Group 5, and Group 6 metals of the periodic table excluding W, and the remainder being WC and unavoidable impurities, and the coating layer comprises an MT-TiCN layer formed on the base material and an α-Al2O3 layer formed on the MT-TiCN layer, wherein the highest priority growth orientation of the α-Al2O3 layer formed on the upper surface of the cutting tool is (0012) and the highest priority growth orientation of the α-Al2O3 layer formed on the side of the cutting tool is (104), and when the Grain Reference Orientation Deviation angle (GROD) of the coating layer is measured by EBSD, A cutting tool is provided having particles in which the internal reference azimuth angle deviation (GROD) of the entire coating layer is 5% or more. Effects of the invention

[0015] As in the present invention, after forming an MT-TiCN layer and an α-Al2O3 layer on the composition of the base material, the highest priority growth orientation of the α-Al2O3 layer formed on the upper surface of the cutting tool is set to (0012) and the highest priority growth orientation of the α-Al2O3 layer formed on the side surface is set to (104), and by controlling the coating layer so that there are particles with an internal reference orientation angle deviation (GROD) of 5% or more, it is possible to suppress crater wear caused by chemical wear, especially during milling, and to suppress the breakage of the cutting tool through improved toughness. Brief explanation of the drawing

[0017] Figure 1 is a perspective view of a coated cutting tool. Figure 2 is the XRD analysis result of the upper surface of a coated cutting tool according to an embodiment. Figure 3 is the XRD analysis result of the side of a coated cutting tool according to an embodiment. Figure 4 shows the result of measuring the Grain Reference Orientation Deviation - angle (GROD) of MT-TiCN using EBSD of a coated cutting tool according to an embodiment. Figure 5 shows the result of measuring the Grain Reference Orientation Deviation angle (GROD) of MT-TiCN using EBSD of a coated cutting tool according to Comparative Example 1. Specific details for implementing the invention

[0018] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0019] In addition, to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0020] Throughout the entire specification, when a component is described as being located "on," "on top," "on top," "under," "on bottom," or "on bottom" of another component, this includes not only cases where the component is in contact with the other component but also cases where another component exists between the two components.

[0021] Throughout this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0022] Throughout this specification, the "MT-TiCN layer" refers to a titanium carbonitride layer formed by medium-temperature chemical vapor deposition (MT-CVD) at a temperature of 830 to 900°C in a gas mixture containing TiCl4, CH3CN, and H2, wherein TiC x N y (Here, x+y means a coating layer (thin film) having a composition of 0.8 to 1.1).

[0023] The coating cutting tool of the present invention comprises a structure including a base material made of cemented carbide and a coating layer formed on the base material.

[0025] [Material]

[0026] FIG. 1 is a perspective view of a coated cutting tool. The base material according to the present invention may be formed into a shape such as that shown in FIG. 1, for example, but FIG. 1 is presented as an example and is not limited to the base material of the present invention being formed into the shape shown in FIG. 1.

[0027] As illustrated in FIG. 1, the base material (100) is formed to include an upper surface (110), a side surface (120) adjacent to the upper surface, a cutting edge (130) formed between the upper surface and the side surface, and a nose portion (140) formed at the corners of the side surface.

[0028] The above base material may be composed of a cemented carbide containing 9 to 12 weight percent of cobalt (Co), 2 weight percent or less of a carbide, carbonitride, or mixture thereof of one or more metals selected from Group 4, Group 5, and Group 6 metals of the periodic table excluding tungsten (W), and the remainder being tungsten carbide (WC) and unavoidable impurities.

[0029] In the above cemented carbide alloy, if the Co content is less than 9 weight%, the hardness of the base material becomes too high, making it difficult to improve tool life in combination with the toughness of the coating layer, and if it exceeds 12 weight%, the wear resistance of the base material decreases, so it is preferable to include it in an amount of 9 to 12 weight%.

[0030] When the content of cubic carbides, carbonitrides, or mixtures thereof (hereinafter referred to as "other carbides") containing one or more metals selected from Group 4, Group 5, or Group 6 of the periodic table excluding tungsten (W) exceeds 2 weight%, chipping resistance is reduced during milling, so it is preferable to have 2 weight% or less. It may be preferable not to include other carbides, or if other carbides are included, to include 0.5 weight% or more to inhibit grain growth and improve heat resistance.

[0032] [Coating layer]

[0033] The coating layer includes an MT-TiCN layer formed on the substrate and an α-Al2O3 layer formed on the MT-TiCN layer.

[0034] Since the wear resistance of the coating layer decreases if the thickness of the MT-TiCN layer is less than 1 μm and the peel resistance of the coating layer decreases if it exceeds 20 μm, it is preferable for the MT-TiCN layer to be formed with a thickness of 1 to 20 μm. In addition, a nitride layer such as TiN may be formed between the MT-TiCN layer and the substrate with a thickness of 0.5 to 5 μm.

[0035] In addition, a carbonate nitride layer such as TiCNO or AlTiCNO can be formed between the MT-TiCN layer and the α-Al2O3 layer with a thickness of 0.5 to 2.5 μm to increase the interlayer bonding strength.

[0036] In addition, the highest priority growth orientation of the MT-TiCN layer may be the (311) plane, or the sum of TC (311) and TC (422) calculated from the texture coefficients (TC) measured by X-ray diffraction using CuKa radiation and θ-2θ scans calculated by the Harris formula of [Equation 1] below may be 4 or greater.

[0037] [Equation 1]

[0038] TC(hkl) = I(hkl) / Io(hkl){1 / n∑I(hkl) / Io(hkl)} -1

[0039] (Here, I(hkl) = (hkl) reflection intensity, Io(hkl) = The (hkl) reflections used according to JCPDS 42-1488 are (111), (200), (220), (311), (420), (422))

[0040] The fact that the highest priority growth orientation is the (311) plane means that among the TC(hkl) obtained in [Equation 1] above, TC(311) is the largest compared to the aggregation coefficient (TC) of other crystal orientation planes.

[0041] As described above, by making the highest priority growth orientation of the MT-TiCN layer the (311) plane, or by making the sum of TC (311) and TC (422) 4 or more, the coating layer can have a fine particle size of 0.05 to 0.5 μm while maintaining chemical stability at high temperatures, so that the chipping resistance can be further improved.

[0042] Since the wear resistance of the coating layer decreases if the thickness of the above α-Al2O3 layer is less than 1㎛ and the peel resistance of the coating layer decreases if it is more than 20㎛, it is preferable to form the layer with a thickness of 1 to 20㎛.

[0043] Additionally, the highest priority growth orientation of the α-Al2O3 layer formed on the upper surface of the cutting tool is (0012), and the highest priority growth orientation of the α-Al2O3 layer formed on the side of the cutting tool may be (104).

[0044] In this way, by setting the highest priority growth orientation of the upper surface to (0012), stable wear resistance characteristics due to chip flow can be obtained, and by setting the highest priority growth orientation of the side surface to (104), toughness due to intermittent, chip friction, etc. can be increased.

[0045] In the case of the highest priority growth orientation of the α-Al2O3 layer, the TC texture using the Harris formula [Equation 1] of the TiCN layer is calculated as a ratio to the reference value I0 for each orientation (hkl) of the reference JCPDS card, so the difference between I0 of (0012) and (104) varies by about 50 to 100 times depending on the JCPDS card, and there is a possibility of distortion in the calculation result even for orientations with high strength.

[0046] Therefore, in the present invention, "the highest priority growth orientation of the α-Al2O3 layer is (0012)" or "the highest priority growth orientation of the α-Al2O3 layer is (014)" refers to the intensity I of the α-Al2O3 layer in the graph obtained by performing X-ray diffraction analysis using CuKa radiation and θ-2θ scans on the α-Al2O3 layer shown in [Figs. 2] and [Figs. 3]. hkl Among, I 0012 or I 014 This means that it is the largest compared to the intensity of all other crystal orientation planes.

[0047] In addition, I of the α-Al2O3 layer formed on the upper surface of the cutting tool 0012 / ( I 0012 +I 104 ) is 0.6 or greater, and I of the α-Al2O3 layer formed on the side of the cutting tool 104 / ( I 0012 +I 104 It is desirable to orient the α-Al2O3 layer to the highest growth priority with a value of 0.7 or higher, as this can achieve improved tool characteristics.

[0048] In addition, the coating layer can be treated such that when the Grain Reference Orientation Deviation (GROD) of the coating layer is measured by EBSD, there are particles in the entire coating layer with an intragrain reference orientation deviation (GROD) of 5% or more.

[0049] In this way, the intragranular orientation deviation obtained during GROD measurement can be implemented by, for example, by changing the orientation within the crystal of the particles using physical force to relieve residual stress, thereby improving the toughness of the entire coating layer.

[0050] More preferably, if the area ratio of particles with an intragranular azimuthal deviation (GROD) of 10% or more in the MT-TiCN layer is adjusted to be 30% or more, and the area ratio of particles with an intragranular azimuthal deviation (GROD) of 10% or more in the α-Al2O3 layer is adjusted to be 30% or more, the toughness of the entire coating layer can be further improved.

[0052] <Example>

[0053] The embodiments and comparative examples of the present invention used raw material powder having a composition of 10 wt% Co, 1.0 wt% TaNbC, and the remainder being WC, mixed and spheroidized, and then molded into a molded body having the model number SPCN1203EDR of Korea Metal. Subsequently, a cemented carbide base material was produced by vacuum sintering at 1,400°C for 1 hour and cooling to room temperature.

[0054] Next, the fabricated base material was subjected to a CVD coating process in a radial type BERNEX CVD coating machine size 530 capable of accommodating 10,000 half-inch cutting inserts, using a pre-coated carbon fixture that allowed the reaction gas to flow horizontally along the upper surface of the insert.

[0055] In forming the coating layer, reduction and etching were performed for 5 minutes using TiCl4 and H2 at 900°C for surface modification, and a 1 µm thick TiN layer was formed using TiCl4, N2 and H2 at the same temperature, followed by coating a 4 µm TiCN layer. During the MTCVD deposition of the TiCN layer, the volume ratio of TiCl4 / CH3CN was set to 3.9.

[0056] A bonding layer with a thickness of 0.5 to 1.5 μm was deposited on the upper surface of the MTCVD TiCN layer at 1,000°C by a process consisting of two separate reaction steps. In the first step, the HT-TiCN process, TiCl4, CH4, N2, HCl, and H2 were used at 400 mbar, and in the second step, TiCl4, CH3CN, AlCl3, CO, N2, and H2 were used at 70 mbar. Then, to form α-Al2O3, the surface of the bonding layer was oxidized in a mixture of CO2, CO, N2, and H2 for 4 minutes.

[0057] The α-Al2O3 layer was deposited in two steps at 1000°C and 80 mbar. The first step formed an Al2O3 layer of approximately 0.7 μm using 1.4 vol% AlCl3, 2.8 vol% CO2, 1.5 vol% CO, 1.6 vol% HCl, and the remainder H2 for 60 minutes, and the second step formed an Al2O3 layer with a total thickness of approximately 4 μm using 1.5 vol% AlCl3, 4.5 vol% CO2, 1.8 vol% HCl, 1 vol% H2S, and the remainder H2 for 350 minutes.

[0058] On the above α-Al2O3 layer, an outermost color layer containing TiN was coated with a thickness of about 1 μm.

[0059] To improve the stress and appearance of the insert after coating, the upper surface of the tool was wet-blasted for 30 seconds per sample with a blaster slurry composed of 10 vol% alumina or zirconia aqueous solution, at a spray nozzle distance of 200 mm and a vertical angle, at a pressure of 2.0 bar.

[0061] <Comparative Example 1>

[0062] For comparison with the example, the sample of Comparative Example 1 had the same composition and CVD coating process as the example for the cemented carbide base material and coating, but for the post-treatment process to improve the stress and appearance of the insert after coating, wet blasting surface treatment was performed on the upper surface of the tool with a blaster slurry composed of 20 vol% alumina aqueous solution at a spray nozzle distance of 200 mm and a vertical angle at a pressure of 1.6 bar for 5 seconds per sample.

[0064] <Comparative Example 2>

[0065] Comparative Example 2 sample for comparison with the example has the same composition as the example cemented carbide base material, and differs in that when forming the coating layer, CH3CN was replaced with CH4 in the second step of the bonding layer on the upper surface of the CVD MT-TiCN layer, and 1.8 vol% AlCl3, 5 vol% CO2, 1.8 vol% CO, 2.8 vol% HCl, 0.3 vol% H2S, and the remainder H2 were used in the second step of forming the Al2O3 layer, and the rest was the same as the example.

[0066] In addition, for a post-treatment process to improve the stress and appearance of the insert after coating, a wet blasting surface treatment was performed on the upper surface of the tool using a blaster slurry composed of a 20 vol% alumina aqueous solution, with a spray nozzle distance of 200 mm, a vertical angle, and a pressure of 1.6 bar for 5 seconds per sample.

[0068] X-ray diffraction analysis

[0069] To investigate the highest priority growth orientation of the coating layer formed according to the examples and comparative examples, X-ray diffraction was performed on the top and side surfaces using a Panalytical EMPYREAN equipped with a PIXcel detector.

[0070] At this time, the coated cutting tool was mounted in a sample holder, and Cu-Ka radiation was used for measurement at a voltage of 45 kV and a current of 40 mA, using a 1-degree anti-scattering slit and a 1 / 4-degree diverging slit. The diffraction intensity from the coated cutting tool was measured in the 2θ range of 20° to 140°. Data analysis, including background removal, Cu-Ka2 stripping, and data profile adjustment, was performed using Panalytical's X'Pert HighScore Plus software, yielding the results shown in Tables 1 and 2 below.

[0071] TiCN I 311 I 422 TC(311)+TC(422) Examples 1073 756 4.3 Comparative Example 1 929 641 4 Comparative Example 2 724 438 3.1

[0072] α-Al2O3 Top priority growth defense I 0012 I 104 I 0012 / (I 0012 +I 104 ) I 104 / (I 0012 +I 104 ) Examples Top surface (0012) 851 402 0.68 0.32 side (104) 274 1647 0.14 0.86 Comparative Example 1 Top surface (0012) 736 608 0.62 0.38 side (104) 199 1420 0.12 0.88 Comparative Example 2 Top surface (104) 47 1797 0.03 0.97 side (104) 24 1675 0.02 0.98

[0074] As shown in Tables 1 and 2 above, in the case of the example and Comparative Example 1 to which the same coating process was applied, the most important growth orientation of the MT-TiCN layer and the α-Al2O3 layer did not change, and the most important growth orientation of MT-TiCN is (311), and TC (311)+TC (422) calculated by Equation 1 above has a value of 4 or greater.

[0075] In addition, the upper surface a-Al2O3 most preferred growth orientation of the coatings in Example and Comparative Example 1 was (0012) and the side surface was (014), and the intensity ratio I of the (0012) orientation on the upper surface 0012 / ( I 0012 +I 104 ) is greater than or equal to 0.6, and the intensity ratio I of the (104) orientation from the side 104 / ( I 0012 +I 104 ) was found to be 0.7 or higher.

[0076] In contrast, in the case of Comparative Example 2 coating, growth occurred in the same (104) orientation without any difference in the highest priority growth orientation between the top surface and the side surface, and the (0012) orientation was difficult to distinguish as a peak in the graph.

[0078] EBSD analysis

[0079] In order to precisely analyze the microstructure of the embodiments and comparative examples of the present invention, the EBSD (Electron Back Scatter Diffraction) analysis method was used on alumina with a Zeiss sigma 300 field emission scanning electron microscope and TSL OIM Analysis 7 program. After mapping with a step size of 50 nm at a measurement distance of 15 mm and an acceleration voltage of 15 kV, the deviation of the azimuth angle due to deformation within the grains of the MT-TiCN layer (Grain reference Orientation Deviation - angle (GROD)) was measured, and the results shown in Figures 4 and 5 were obtained. The GRODs of the embodiments, comparative examples 1 and 2 obtained therefrom were as shown in Tables 3 and 4 below.

[0080] As shown in Table 3, the deformation state of the uppermost alumina film was similar, and the difference between Comparative Example 1 and 2 is that the (001) orientation alumina has higher hardness, so there is less deformation due to post-treatment and consequently less damage to the film, so there is less reduction in wear resistance performance.

[0081] In the case of the MT-TiCN coating of the embodiment of the present invention, it can be indicated whether the stress relief effect of the post-treatment applied from the top of the coating, located at the bottom of the thin film, has affected the entire thin film. As shown in Table 4, the GROD analysis results showed that the proportion of the total deformation was 10% or more was 46.7%, whereas in the case of the coatings of Comparative Examples 1 and 2, the GROD analysis results showed that the proportion of the total deformation was 12.7% and 10.5%, respectively.

[0082] Sample GROD, percentage of a-Al2O3 azimuth deviations of 10% or more Examples 37.2% Comparative Example 1 34.1% Comparative Example 2 47.2%

[0083] Sample GROD, MT-TiCN percentage of azimuth deviations of 10% or more Examples 46.7% Comparative Example 1 12.7% Comparative Example 2 10.5%

[0085] Cutting performance evaluation

[0086] The wear resistance and chipping resistance of the coated cutting tools manufactured according to the embodiments and comparative examples of the present invention were evaluated under the following evaluation conditions.

[0087] (1) Wear resistance evaluation: Insert clearance surface, inclined surface wear

[0088] Workpiece: S45C, 100×200×300

[0089] Sample Model Number: SPCN1203EDR

[0090] Cutting speed: 300 m / min

[0091] Cutting feed: 0.25mm / tooth

[0092] Cutting depth (ae): 100mm

[0093] Cutting depth (ap): 1.5mm

[0094] Cutting fluid: Dry

[0095] (2) Toughness evaluation: Insert breakage

[0096] Workpiece: SCM440, 25×200×300 3EA, Intermittent

[0097] Sample Model Number: SPCN1203EDR

[0098] Cutting speed: 200 m / min

[0099] Cutting feed: 0.2mm / rev

[0100] Cutting depth (ae): 100mm

[0101] Cutting depth (ap): 1.5mm

[0102] Cutting fluid: Dry

[0104] As can be seen in Table 5 below, in the wear resistance evaluation, Comparative Example 1 showed that α-Al2O3(0012) grew preferentially on the upper surface compared to Comparative Example 2, which delayed upper surface wear, but the toughness was insufficient because stress relief by post-treatment was not achieved throughout the entire thin film.

[0105] In addition, Comparative Example 2 has an effect of improving the toughness of the thin film in which α-Al2O3 (104) is grown most preferentially, but the wear resistance of the upper surface is insufficient.

[0106] Compared to the coated cutting tools manufactured according to the embodiment of the present invention, the tool life is increased by improving toughness in a balanced manner by relieving stress throughout the upper surface and lower surface of the coating in response to the wear mechanism required on the upper surface and the side surface.

[0107] Sample Wear resistance evaluation Personality assessment Tool life (PASS) Tool life (breakage, Pass) Examples 25 16 Comparative Example 1 23 7 Comparative Example 2 14 12 Explanation of the symbols

[0109] 100: Base material 200: Top surface 300: Side 400: Personnel Selection Department 500: Nose

Claims

Claim 1 A cutting tool comprising a base material having an upper surface, a side adjacent to the upper surface, and a cutting edge formed between the upper surface and the side, and a coating layer formed on at least one part of the base material, wherein the base material is composed of a cemented carbide comprising 9 to 12 wt% Co, 2 wt% or less of a carbide, carbonitride, or mixture thereof of one or more metals selected from Group 4, Group 5, and Group 6 metals of the periodic table excluding W, and the remainder being WC and unavoidable impurities, and the coating layer comprises an MT-TiCN layer formed on the base material and an α-Al2O3 layer formed on the MT-TiCN layer, wherein the highest priority growth orientation of the α-Al2O3 layer formed on the upper surface of the cutting tool is (0012) and the highest priority growth orientation of the α-Al2O3 layer formed on the side of the cutting tool is (104), and when the Grain Reference Orientation Deviation angle (GROD) of the coating layer is measured by EBSD, the intragrain reference of the entire coating layer A cutting tool containing particles with an azimuth deviation (GROD) of 5% or more. Claim 2 A cutting tool according to claim 1, wherein the area ratio of particles having an intragranular reference azimuth deviation (GROD) of 5% or more in the MT-TiCN layer is 30% or more, and the area ratio of particles having an intragranular reference azimuth deviation (GROD) of 10% or more in the α-Al2O3 layer is 30% or more. Claim 3 A cutting tool according to claim 1, wherein the highest priority growth orientation of the MT-TiCN layer is the (311) plane, or the sum of the texture coefficients (TC) TC (311) and TC (422), which are texture coefficients measured by X-ray diffraction using CuKa radiation and θ-2θ scans calculated by [Equation 1] below, is 4 or greater. [Equation 1] TC(hkl) = I(hkl) / Io(hkl){1 / n∑I(hkl) / Io(hkl)}-1 (where I(hkl) = (hkl) reflection intensity, Io(hkl) = the (hkl) reflections used according to JCPDS 42-1488 are (111), (200), (220), (311), (420), (422)) Claim 4 In claim 1, the intensity I of the graph measured by X-ray diffraction using CuKa radiation and θ-2θ scan hkl Among them, I of the α-Al2O3 layer formed on the upper surface 0012 / ( I 0012 +I 104 ) is 0.6 or higher, and I of the α-Al2O3 layer formed on the above side 104 / ( I 0012 +I 104 A cutting tool that is 0.7 or higher. Claim 5 A cutting tool according to any one of claims 1 to 4, wherein the thickness of the MT-TiCN layer is 1 to 20 μm and the thickness of the α-Al2O3 layer is 1 to 20 μm.

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