JP2009006426A - Surface coated cutting tool with hard coating layer exerting superior wear resistance in high speed cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cutting tool with a hard coating layer exerting superior wear resistance in high speed cutting. <P>SOLUTION: In this surface coated cutting tool, an upper part layer of the hard coating layer is constituted of an aluminum oxide layer, and a lower part layer is constituted of an adhesion Ti compound layer and a reformed (Ti<SB>1-X</SB>Zr<SB>X</SB>)CN layer (X=0.02 to 0.25 in an atomic ratio). The reformed (Ti, Zr)CN layer shows an inclination angle frequency distribution graph measuring and totalizing inclination angles formed by normals of ä111} faces of crystal gains of an external layer, in which a highest peak exists in an inclination angle section in the range of 0 to 10 degrees and a total of frequency existing in the inclination angle section occupies a rate of 45% or more of the frequency total in the inclination angle frequency distribution graph. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent wear resistance with a hard coating layer, particularly in high-speed cutting with high heat generation such as steel and cast iron.

Conventionally, generally on the surface of a substrate (hereinafter collectively referred to as a tool substrate) composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet. ,
(A) The first layer comprises a titanium nitride (hereinafter referred to as TiN) layer formed by chemical vapor deposition and a titanium carbonitride (hereinafter referred to as TiCN) layer, and has an average layer thickness of 0.1 to 1 μm. 1 adhesive bonding layer,
(B) The second layer is formed by chemical vapor deposition,
Composition formula: (Ti _1-X Zr _X ) CN (wherein X is 0.02 to 0.25 in atomic ratio),
A Ti—Zr carbonitride [hereinafter referred to as (Ti, Zr) CN] layer comprising a composite carbonitride layer of Ti and Zr satisfying the above and having an average layer thickness of 2.5 to 15 μm,
(C) A second adhesive joint comprising a titanium carbonate (hereinafter referred to as TiCO) layer and a titanium carbonitride oxide (hereinafter referred to as TiCNO) layer as the third layer and having an average layer thickness of 0.1 to 1 μm. layer,
(D) As a fourth layer, a high-temperature hard layer comprising an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer formed by chemical vapor deposition and having an average layer thickness of 1 to 15 μm,
A coated tool formed by forming a hard coating layer composed of the above (a) to (d) is known, and this coated tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is also known that
JP 2001-11632 A

In recent years, the performance of cutting machines has been remarkable, while there has been a strong demand for labor saving and energy saving in cutting, as well as cost reduction, and along with this, the tendency to increase cutting speed for the purpose of improving cutting efficiency However, in the above-mentioned conventional coated tool, there is no problem when it is used for continuous cutting and intermittent cutting under normal conditions such as steel and cast iron, but especially when this is used under high-speed cutting conditions. The hard coating layer constituting this has high temperature strength due to the Ti compound layer of the lower layer and high temperature hardness due to the Al ₂ O ₃ layer of the upper layer, but heat resistance due to the conventional (Ti, Zr) CN layer. Insufficient performance is likely to cause thermoplastic deformation and uneven wear due to heat generated during cutting, so that the wear resistance is lowered and the service life is reached in a relatively short time.

In view of the above, the inventors of the present invention, from the above viewpoint, in order to improve the wear resistance of the hard coating layer of the above-mentioned coated tool, the TiCN layer constituting the Ti compound layer as the lower layer thereof, that is, the Ti compound As a result of conducting research by paying attention to a (Ti, Zr) CN layer in which a part of Ti having a relatively high high-temperature strength is replaced with Zr in the layer,
(A) In a hard coating layer of a conventional coated tool, a (Ti, Zr) CN layer (hereinafter referred to as “conventional (Ti, Zr) CN layer”) among the Ti compound layers constituting the lower layer is, for example, usually In chemical vapor deposition equipment,
Reaction gas composition: by _{volume%, TiCl 4: 1~5%,} ZrCl 4: 0.1~1%, CH 3 CN: 0.6~5%, N 2: 25~45%, H 2: remainder,
Reaction atmosphere temperature: 750-980 ° C.
Reaction atmosphere pressure: 2.7 to 13.5 kPa,
It is formed by vapor deposition under the conditions (called normal conditions).
Reaction gas composition: by _{volume%, TiCl 4: 10~15%,} ZrCl 4: 0.5~3.5%, CH 3 CN: 3~8%, N 2: 20~40%, HCl: 0.5 ~2%, H _2: remainder,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 5 to 20 kPa,
In comparison with the above-mentioned conditions, that is, the above-mentioned normal conditions, the content ratio of the reaction gas components TiCl ₄ and CH ₃ CN is increased, and further, vapor deposition is performed under the condition of adding HCl,
When a (Ti, Zr) CN layer satisfying the composition formula: (Ti _1-X Zr _X ) CN (wherein the atomic ratio is X: 0.02 to 0.25) is formed, the resulting (Ti, Zr ) The CN layer (hereinafter referred to as the modified (Ti, Zr) CN layer) has the same crystal structure as the conventional (Ti, Zr) CN layer, that is, Ti, Zr, carbon (C), and nitrogen at lattice points. It has a NaCl-type face-centered cubic crystal structure in which each of the constituent atoms made of (N) is present, but has a heat resistance that is far superior to that of the conventional (Ti, Zr) CN layer.

(B) For the conventional (Ti, Zr) CN layer and the modified (Ti, Zr) CN layer of (a),
Using a field emission scanning electron microscope, as illustrated in the schematic explanatory diagrams of FIGS. 1A and 1B, the electron beam is individually applied to each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface. Is measured with respect to the normal of the surface polished surface, and the tilt angle formed by the normal of the {111} plane that is the crystal plane of the crystal grain is measured. When the measured inclination angle in the range of 0.25 degrees is divided for each pitch of 0.25 degrees and the inclination angle number distribution graph is formed by counting the frequencies existing in each division, the conventional (Ti, Zr) As illustrated in FIG. 3, the CN layer exhibits an unbiased inclination angle number distribution graph in the range of the measured inclination angle of the {111} plane within the range of 0 to 45 degrees, whereas the modification ( As illustrated in FIG. 2, the Ti, Zr) CN layer has a sharp peak at a specific position in the tilt angle section. A peak appears, and in such a case, cooling cracks are uniformly dispersed in the modified (Ti, Zr) CN layer, and thereby the modified (Ti, Zr) CN layer due to an increase in the Zr content. In addition, the sharp maximum peak has a height that appears in the tilt angle section of the horizontal axis of the graph and the position of the tilt angle section in the Zr in the modified (Ti, Zr) CN layer. It changes by adjusting the content ratio.

(C) As described above, when forming the modified (Ti, Zr) CN layer, the Zr content ratio in the layer is 0.02 to 0.25 as a ratio (atomic ratio) to the total amount with Ti. By doing this, in the gradient angle distribution graph of the modified (Ti, Zr) CN layer, a sharp maximum peak appears in the range of 0 to 10 degrees of the tilt angle section, and the range of 0 to 10 degrees In the modified (Ti, Zr) CN layer, the frequency ratio existing in the tilt angle frequency distribution graph occupies a ratio of 45% or more of the entire frequency in the tilt angle frequency distribution graph. Even if the Zr content ratio is out of the above range, the sharp maximum peak in the tilt angle distribution graph is out of the range of 0 to 10 degrees of the tilt angle section, and Within the range of 0 to 10 degrees The frequency ratio is also less than 45%. In this case, not only can the heat resistance improvement effect be further improved, but also the decrease in high-temperature strength due to the increase in the Zr content ratio should be suppressed by uniform distribution of cooling cracks. What you can't do.
That is, the Zr component of the modified (Ti, Zr) CN layer has a desired heat resistance improvement effect when the ratio (atomic ratio) to the total amount with Ti is 0.02 (2 atomic%) or more. When the content ratio exceeds 0.25 (25 atomic%), the modified (Ti, Zr) CN layer softens rapidly during high-speed cutting with high heat generation, and it is likely to cause thermoplastic deformation and uneven wear. Therefore, the content ratio needs to be 0.02 to 0.25 in the ratio (atomic ratio) to the total amount with Ti.

(D) the upper layer is the Al ₂ O ₃ layer of the hard coating layer, the lower layer adhesion Ti compound layer and the reforming (Ti, Zr) consists of a CN layer and reforming (Ti, Zr) CN layer However, it has an average layer thickness of 2.5 to 15 μm, and the distribution of the measured inclination angle of the {111} plane shows the highest peak of the inclination angle section within the range of 0 to 10 degrees, and the 0 to 10 degrees In the coated tools with a frequency ratio of 45% or more existing in the range, the modified (Ti, Zr) CN layer has a much higher heat resistance than the conventional (Ti, Zr) CN layer. Combined with the excellent high-temperature hardness of the Al ₂ O ₃ layer, which is a partial layer, the hard coating layer exhibits excellent heat resistance, especially in high-speed cutting with high heat generation, and thermoplastic deformation Because it does not cause uneven wear, it should show excellent wear resistance over a long period of time.
The research results shown in (a) to (d) above were obtained.

This invention was made based on the above research results, and in the surface-coated cutting tool in which a hard coating layer composed of an upper layer and a lower layer is formed on the surface of the tool base by vapor deposition,
(A) The upper layer is made of an aluminum oxide layer having an average layer thickness of 1 to 15 μm formed by chemical vapor deposition,
(B) The lower layer has a total average layer thickness of 3 to 20 μm, and each consists of an adhesive Ti compound layer and a modified Ti carbonitride layer formed by chemical vapor deposition,
(C) The adhesion Ti compound layer is composed of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride oxide layer having a total average layer thickness of 0.5 to 5 μm. It consists of one or more layers,
(D) The modified Ti carbonitride layer (modified (Ti, Zr) CN) layer has an average layer thickness of 2.5 to 15 μm, and
Composition formula: (Ti _1-X Zr _X ) CN
Is expressed by a composite carbonitride layer of Ti and Zr satisfying 0.02 ≦ X ≦ 0.25 (however, atomic ratio), and further, the modified Ti-based carbonitride layer (modified ( The Ti, Zr) CN layer) is irradiated with an electron beam to each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface using a field emission scanning electron microscope, and the surface polished surface The inclination angle formed by the normal line of the {111} plane that is the crystal plane of the crystal grain is measured with respect to the normal line, and the measurement inclination angle in the range of 0 to 45 degrees is set to 0 among the measurement inclination angles. In the inclination angle number distribution graph obtained by dividing the pitch every 25 degrees and counting the frequencies existing in each section, the highest peak exists in the inclination angle section in the range of 0 to 10 degrees, and The total frequency within the range of 0 to 10 degrees is the slope angle distribution graph. To indicate an inclination angle frequency distribution graph in a proportion of 45% or more of total power,
A surface-coated cutting tool (coated tool) that exhibits excellent wear resistance with a hard coating layer in high-speed cutting, characterized by
It has the characteristics.

Next, the reason why the constituent layers of the hard coating layer of the coated tool of the present invention are numerically limited as described above will be described below.
(A) Adhesive Ti compound layer of lower layer Adhesive Ti compound layer adheres firmly to both the tool base and the Al ₂ O ₃ layer and the modified Ti carbonitride layer which are the upper layer, and is therefore hard Although it has the effect | action which contributes to the adhesive improvement with respect to the tool base | substrate of a coating layer, if the total average layer thickness is less than 0.5 micrometer, desired outstanding adhesiveness cannot be ensured, On the other hand, the said adhesiveness is up to 5 micrometers. Therefore, the total average layer thickness was determined to be 0.5 to 5 μm.

(B) Modified Ti-based carbonitride (modified (Ti, Zr) CN) layer in the lower layer The number of inclination angles of the modified Ti-based carbonitride layer, that is, the modified (Ti, Zr) CN layer As described above, the highest peak position in the inclination angle section of the distribution graph and the frequency ratio existing in the predetermined inclination angle section where the highest peak exists are obtained by setting the Zr content ratio (X value) in the layer to the total amount of Ti. By making the atomic ratio to be 0.02 to 0.25, the highest peak is present in the inclination angle section in the range of 0 to 10 degrees, and the frequency ratio existing in the range of 0 to 10 degrees is The inclination angle frequency distribution graph can be 45% or more of the total frequency, and therefore the inclination angle at which the highest peak position appears even if the content ratio is less than 0.02 or exceeds 0.25. The section falls outside the range of 0-10 degrees, The frequency ratio existing in the range of 0 to 10 degrees is less than 45%. Therefore, not only the decrease in high-temperature strength cannot be suppressed by uniform distribution of cooling cracks, but also excellent in high-speed cutting. The effect of improving heat resistance cannot be ensured, and the wear resistance is inferior due to the occurrence of thermoplastic deformation or uneven wear.
In addition, the C component in the modified (Ti, Zr) CN layer improves the hardness of the layer, while the N component has the effect of improving the high-temperature strength. Therefore, if the content ratio of the N component in the layer is less than 0.35 in terms of the atomic ratio to the total amount with the C component, the desired strength can be secured. On the other hand, if the content ratio similarly exceeds 0.55, the content ratio of the C component is relatively decreased, and the desired high hardness cannot be obtained. Therefore, the N component occupies the total amount with the C component. The content ratio of is desirably 0.35 to 0.55 in atomic ratio.
As described above, the modified (Ti, Zr) CN layer has higher heat resistance than the conventional (Ti, Zr) CN layer as described above, but the average layer thickness is 2. If the thickness is less than 5 μm, the desired excellent heat resistance improvement effect cannot be sufficiently provided in the hard coating layer. On the other hand, if the average layer thickness exceeds 15 μm, chipping tends to occur. It was set to 2.5 to 15 μm.

The Al ₂ O ₃ layer the Al ₂ O ₃ layer (c), the upper layer has excellent high-temperature hardness, contributes to improvement in wear resistance of the hard coating layer, the average layer thickness is less than 1 [mu] m, hard Since the coating layer cannot exhibit sufficient wear resistance, on the other hand, if the average layer thickness exceeds 15 μm, chipping tends to occur. Therefore, the average layer thickness is set to 1 to 15 μm. It was.

  In addition, for the purpose of identification before and after the use of the cutting tool, the TiN layer having a golden color tone may be vapor-deposited as necessary, but the average layer thickness in this case is 0.1 to 1 μm may be sufficient, and if the thickness is less than 0.1 μm, a sufficient discrimination effect cannot be obtained, while the discrimination effect by the TiN layer is sufficient for an average layer thickness of up to 1 μm.

  The coated tool of the present invention has excellent heat resistance and high-temperature strength in the modified (Ti, Zr) CN layer of the lower layer of the hard coating layer even in high-speed cutting such as steel and cast iron with high heat generation. However, by suppressing the occurrence of thermoplastic deformation and uneven wear, the hard coating layer exhibits excellent wear resistance.

  Next, the coated tool of the present invention will be specifically described with reference to examples.

As raw material powders, both WC powder having an average particle size of 0.5 to 3 [mu] m, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder These raw material powders were blended into the blending composition shown in Table 1, and then added with wax, ball milled in acetone for 36 hours, dried under reduced pressure, and then formed into a compact with a predetermined shape at a pressure of 98 MPa. The green compact was press-molded and vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour. After sintering, the cutting edge portion had R: 0.05 mm. The tool bases A to F made of a WC-base cemented carbide having a throwaway tip shape specified in ISO · CNMG12041 were manufactured by performing the honing process.

Further, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, blend these raw material powders into the composition shown in Table 2, wet-mix for 36 hours with a ball mill, dry, and press-mold into green compact at 98 MPa pressure The green compact is sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after the sintering, the cutting edge portion is subjected to a honing process of R: 0.05 mm. Tool bases a to f made of TiCN-based cermet having a chip shape conforming to ISO standards / CNMG 120212 were formed.

Next, on the surfaces of these tool bases A to F and tool bases a to f, an ordinary chemical vapor deposition apparatus is used, and an adhesive Ti compound layer and a modified (Ti, Zr) CN are used as a lower layer of the hard coating layer. A lower layer composed of layers is formed by vapor deposition with the combinations and target layer thicknesses shown in Table 4 under the conditions shown in Table 3, and then an Al ₂ O ₃ layer as an upper layer is formed under the same conditions shown in Table 3. Similarly, the coated tools 1 to 13 of the present invention were manufactured by vapor deposition with a combination shown in Table 4 and with a target layer thickness.

For comparison, an adhesive Ti compound layer and a conventional (Ti, Zr) CN layer are deposited as the lower layer of the hard coating layer under the conditions shown in Table 3 and the combinations and target layer thicknesses shown in Table 5. Then, the conventional coated tools 1 to 13 were manufactured by depositing and forming an Al ₂ O ₃ layer as an upper layer under the conditions shown in Table 3 and with the target layer thicknesses also shown in Table 5.

Next, the modified (Ti, Zr) CN layer and the conventional (Ti, Zr) CN layer constituting the hard coating layer of the present invention coated tool and the conventional coated tool are tilted using a field emission scanning electron microscope. Each angle distribution graph was created.
That is, the inclination angle number distribution graph shows the inside of the column of the field emission scanning electron microscope in a state where the surfaces of the modified (Ti, Zr) CN layer and the conventional (Ti, Zr) CN layer are polished surfaces. Irradiating the polished surface with an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees with an irradiation current of 1 nA on each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface Then, using an electron backscatter diffraction image apparatus, a {111} plane which is a crystal plane of the crystal grain with respect to a normal line of the surface-polished surface in a 30 × 50 μm region at an interval of 0.1 μm / step The inclination angle formed by the normal line is measured, and based on the measurement result, among the measurement inclination angles, the measurement inclination angle within the range of 0 to 45 degrees is divided for each pitch of 0.25 degrees, Created by counting the frequencies existing in each category It was.

    In the inclination angle number distribution graphs of the various modified (Ti, Zr) CN layers and conventional (Ti, Zr) CN layers obtained as a result, the inclination angle division in which the {111} plane shows the highest peak, and 0-10 Tables 4 and 5 show the ratio of the number of tilt angles existing in the tilt angle section within the degree range to the number of tilt angles in the entire tilt angle distribution graph.

In the above-mentioned various inclination angle number distribution graphs, as shown in Table 4, the modified (Ti, Zr) CN layers of the inventive coated tools 1 to 13 all have a distribution of measured inclination angles on the {111} plane. An inclination angle number distribution graph in which the highest peak appears in the inclination angle section in the range of 0 to 10 degrees, and the ratio of the inclination angle numbers existing in the inclination angle section in the range of 0 to 10 degrees is 45% or more. On the other hand, as shown in Table 5, the conventional (Ti, Zr) CN layers of the conventional coated tools 1 to 13 all have a measured inclination angle distribution on the {111} plane within the range of 0 to 45 degrees. And the inclination angle number distribution graph in which the highest peak does not exist and the ratio of the inclination angle number existing in the inclination angle section within the range of 0 to 10 degrees is 30% or less.
2 is a graph showing the distribution of the tilt angle number of the modified (Ti, Zr) CN layer of the coated tool 2 of the present invention, and FIG. 3 is the distribution of the tilt angle number of the conventional (Ti, Zr) CN layer of the conventional coated tool 2. Each graph is shown.

Further, regarding the above-described coated tools 1 to 13 of the present invention and the conventional coated tools 1 to 13, the hard coating layer was observed using an electron beam microanalyzer (EPMA) and an Auger spectrometer (longitudinal section of the layer). The adhesive Ti compound layer, the modified (Ti, Zr) CN layer, the conventional (Ti, Zr) CN layer, and the Al ₂ O ₃ layer having substantially the same composition as the target composition in both the former and the latter. It was confirmed to consist of layers. Moreover, when the thickness of the constituent layer of the hard coating layer of these coated tools was measured using a scanning electron microscope (similarly longitudinal section measurement), the average layer thickness (5 The average value of point measurement) was shown.

Next, with the various coated cermet tools described above, the present coated tools 1 to 13 and the conventional coated tools 1 to 13 in a state where all of the above-mentioned coated cermet tools are screwed to the tip of the tool steel tool with a fixing jig.
Work material: JIS / SCr420H round bar,
Cutting speed: 420 m / min,
Cutting depth: 1.3 mm,
Feed: 0.28 mm / rev,
Cutting time: 7 minutes,
Wet continuous high-speed cutting test (normal cutting speed is 250 m / min) of alloy steel under the conditions (referred to as cutting condition A),
Work material: JIS / SUM11 round bar,
Cutting speed: 415 m / min,
Cutting depth: 1.5 mm,
Feed: 0.29 mm / rev,
Cutting time: 7 minutes,
Wet continuous high-speed cutting test (normal cutting speed is 200 m / min) of free-cutting steel under the following conditions (referred to as cutting condition B),
Work material: JIS / FC150 round bar,
Cutting speed: 450 m / min,
Incision: 2 mm,
Feed: 0.3 mm / rev,
Cutting time: 7 minutes,
A wet continuous high-speed cutting test (normal cutting speed is 300 m / min) of cast iron under the above conditions (referred to as cutting conditions C),
In any cutting test (using water-soluble cutting oil), the flank wear width of the cutting edge was measured. The measurement results are shown in Table 6.

  From the results shown in Tables 4 to 6, all of the coated tools 1 to 13 of the present invention have a modified (Ti, Zr) CN layer in the lower layer of the hard coating layer, and the inclination angle of the {111} plane is 0. An inclination angle distribution graph showing the highest peak in the inclination angle section within the range of -10 degrees, and the total ratio of the frequencies existing in the inclination angle section range of 0 to 10 degrees occupying 45% or more is high. Even in high-speed cutting of steel and cast iron with heat generation, the modified (Ti, Zr) CN layer has excellent heat resistance and high-temperature strength, and prevents the occurrence of thermoplastic deformation and uneven wear. While the coating layer exhibits excellent wear resistance, the conventional (Ti, Zr) CN layer of the lower layer of the hard coating layer has a measured inclination angle distribution on the {111} plane of 0 to 45 degrees. Conventionally showing an inclination angle distribution graph that is unbiased within the range and does not have the highest peak ( i, Zr) In the conventional coated tools 1 to 13 composed of CN layer, the hard coating layer has extremely poor wear resistance due to occurrence of thermoplastic deformation or partial wear of the hard coating layer in high speed cutting. It is clear that the service life is reached in a relatively short time.

  As described above, the coated tool of the present invention has excellent resistance to hard coating even in high-speed cutting with high heat generation, as well as continuous cutting and intermittent cutting under normal conditions such as various steels and cast iron. Because it exhibits wearability and exhibits excellent cutting performance over a long period of time, it can sufficiently satisfy the high performance of cutting equipment, labor saving and energy saving of cutting, and cost reduction. .

It is a schematic explanatory drawing which shows the measurement range of the inclination angle of the {111} plane of crystal grains in the modified (Ti, Zr) CN layer and the conventional (Ti, Zr) CN layer constituting the lower layer of the hard coating layer. It is an inclination angle number distribution graph of the {111} plane of the modified (Ti, Zr) CN layer constituting the lower layer of the hard coating layer of the present coated tool 2. It is the inclination angle number distribution graph of the {111} plane of the conventional (Ti, Zr) CN layer which comprises the lower layer of the hard coating layer of the conventional coating tool 2. FIG.

Claims (1)

In a surface-coated cutting tool in which a hard coating layer composed of an upper layer and a lower layer is vapor-deposited on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
(A) The upper layer is made of an aluminum oxide layer having an average layer thickness of 1 to 15 μm formed by chemical vapor deposition,
(B) The lower layer has a total average layer thickness of 3 to 20 μm, and each consists of an adhesive Ti compound layer and a modified Ti carbonitride layer formed by chemical vapor deposition,
(C) The adhesion Ti compound layer is composed of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride oxide layer having a total average layer thickness of 0.5 to 5 μm. It consists of one or more layers,
(D) The modified Ti carbonitride layer has an average layer thickness of 2.5 to 15 μm, and
Composition formula: (Ti _1-X Zr _X ) CN
In this case, it is composed of a composite carbonitride layer of Ti and Zr that satisfies 0.02 ≦ X ≦ 0.25 (however, the atomic ratio), and the modified Ti-based carbonitride layer further comprises field emission. Using a scanning electron microscope, irradiate each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface with an electron beam, and the crystal of the crystal grain with respect to the normal of the surface polished surface Measuring the inclination angle formed by the normal of the {111} plane that is a surface, and dividing the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles for each pitch of 0.25 degrees; In the slope angle distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the tilt angle section within the range of 0 to 10 degrees, and the frequencies existing in the range of 0 to 10 degrees. Is a ratio of 45% or more of the total frequency in the slope angle distribution graph To indicate an inclination angle frequency distribution graph occupied,
A surface-coated cutting tool that exhibits excellent wear resistance with a hard coating layer in high-speed cutting.

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