JP5594573B2 - Surface-coated cutting tool with excellent peeling resistance and wear resistance due to its hard coating layer - Google Patents

Description

  This invention, for example, even when cutting hard steel such as alloy tool steel and hardened material of bearing steel under high-speed heavy cutting conditions with high heat generation and mechanical high load, the hard coating layer is peeled, The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent wear resistance over a long period of use without causing chipping.

As shown in Patent Document 1, conventionally, a substrate composed of tungsten carbide (hereinafter referred to as WC) based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) based cermet (hereinafter collectively referred to as a tool). On the surface of the substrate)
(A) The lower layer is a Ti compound layer,
(B) The upper layer has an α-type crystal structure in a state in which chemical vapor deposition is formed, and an inclination within a range of 0 to 10 degrees in an inclination angle number distribution graph obtained by counting the frequencies existing in each section. Α showing an inclination angle distribution graph in which the highest peak exists in the angle section and the total of the frequencies existing in the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire frequencies in the inclination angle distribution graph. Type Al ₂ O ₃ layer,
A coated tool formed by forming a hard coating layer (referred to as a conventional coated tool 1) is known, and this conventional coated tool 1 is superior in the high-temperature strength of the upper layer, so alloy steel, carbon steel, It is known to show excellent chipping resistance by high-speed intermittent cutting of cast iron or the like.
Further, as shown in Patent Document 2, on the surface of the tool base,
(A) The lower layer is a Ti compound layer,
(B) The upper layer has a flat-plate polygonal shape (including a flat hexagonal shape) and a long and long crystal grain structure structure, and crystals having an area ratio of 60% or more among the crystal grains of the upper layer The inside of the grain is a Zr-containing α-type Al ₂ O ₃ layer (hereinafter referred to as a conventional AlZrO layer) that is divided by a crystal lattice interface composed of at least one constituent atom shared lattice point represented by Σ3,
A coated tool formed by forming a hard coating layer (referred to as a conventional coated tool 2) is known. The conventional coated tool 2 has an upper layer of a hard coated layer having excellent high-temperature hardness and high-temperature strength. Since it has surface properties, it is known to exhibit excellent chipping properties in high-speed heavy cutting of alloy steel, carbon steel, cast iron and the like.

However, both the conventional coated tool 1 and the conventional coated tool 2 aim to improve the characteristics of the hard coating layer as a whole, but the coated tool has different characteristics required for the rake face and the flank face. It is also known to impart characteristics according to each surface.
For example, as shown in Patent Document 3, for the TiCN layer constituting the lower layer of the hard coating layer, by making the (422) plane orientation coefficient of the TiCN layer on the rake face larger than that on the flank face, A coated tool (hereinafter referred to as a conventional coated tool 3) is also known which has improved impact resistance and at the same time improved wear resistance on the flank.

JP-A-2005-205586 JP 2009-172748 A JP 2006-305714 A

  In recent years, the performance of cutting machines has been dramatically improved, while on the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting work, and along with this, cutting work tends to be further speeded up. In tools 1 to 3, there is no particular problem when this is used for high-speed cutting of ordinary steel, cast iron, etc., but this is particularly true for high-hardness steel such as alloy tool steel and hardened material of bearing steel. When used for high-speed heavy cutting with high heat generation and high mechanical load on the cutting edge of the coated tool, it takes a relatively short time, especially due to peeling of the hard coating layer on the rake face or reduced wear resistance. At present, the service life is reached.

  In view of the above, the present inventors have long-term use even when used for high-speed heavy cutting of high hardness steel with high heat generation and mechanical high load at the cutting edge of the cutting tool. As a result of earnest research to develop a coated tool that exhibits excellent peeling resistance and wear resistance, the following knowledge was obtained.

In the above conventional coated tool, after forming a lower layer made of a Ti compound, subsequently, an upper layer (for example, the α-type Al ₂ O ₃ layer in the conventional coated tool 1 or the conventional coated tool 2 described above). In order to improve the cutting performance of the coated tool, the upper layer is also formed through an intermediate layer. When the α-type Al ₂ O ₃ layer in the tool 1 was used as an intermediate layer, and the conventional AlZrO layer in the conventional coated tool 2 was further formed thereon as an upper layer, an attempt was made to improve the cutting performance of the coated tool. When used for high-speed heavy cutting of hardened steel such as alloy tool steel and bearing steel quenching material, the peeling resistance and wear resistance of the hard coating layer on the rake face are still insufficient. It came to a conclusion It was.

Therefore, the present inventors have conducted further research, and after forming a lower layer made of a Ti compound over the entire tool base surface, the film formation process was temporarily interrupted, and a Ti compound layer formed on the rake face ( When the lower layer is subjected to laser treatment, an α-type Al ₂ O ₃ layer as an intermediate layer and a Zr-containing α-type Al ₂ O ₃ layer as an upper layer are formed under predetermined conditions. In particular, the crystal orientation of the intermediate layer of the rake face and the crystal orientation and crystal structure of the upper layer can be made different from those of the flank face and the cutting edge portion, and thereby the hard coating layer of the rake face. As a result, it is possible to improve the wear resistance of the steel, and to improve the wear resistance, it is possible to obtain a coated tool with excellent peel resistance and wear resistance even in high-speed cutting of hardened steel with high heat generation. I found out
Note that the rake face, flank face and cutting edge in the present invention are as shown in the schematic diagram of FIG. 7, but the curved surface is in contact with the rake face and flank face of the coated tool and has a curvature. The part surrounded by is the cutting edge part. However, when the rake face and the flank face intersect linearly and the part surrounded by the curve is not formed, the part surrounded by the film depth direction from the intersection of the straight lines (shaded area in FIG. 7) is the cutting edge. Part.

This invention has been made based on the above findings,
“(1) On the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) the lower layer is formed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer, all formed by chemical vapor deposition; And a Ti compound layer having a total average layer thickness of 2 to 15 μm,
(B) the intermediate layer has an average layer thickness of 1 to 5 μm, and an aluminum oxide layer having an α-type crystal structure in the state of chemical vapor deposition;
(C) the upper layer has an average layer thickness of 2 to 15 μm, and a Zr-containing aluminum oxide layer having an α-type crystal structure in a chemical vapor deposited state;
In the surface-coated cutting tool in which the hard coating layer composed of the above (a) to (c) is formed by vapor deposition,
For the intermediate layer of (b) and the upper layer of (c), each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface of the tool base is measured using a field emission scanning electron microscope. Irradiated with an electron beam, the inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal line of the surface-polished surface. When the measured inclination angle within the range of 45 degrees is divided for each pitch of 0.25 degrees and the frequency existing in each division is represented by an inclination angle number distribution graph,
(D) The intermediate layer in the rake face has the highest peak in the inclination angle section within the range of 0 to 10 degrees, and the total of the frequencies existing in the range of 0 to 10 degrees is the inclination angle number distribution graph. Accounted for 20% or more and less than 45% of the entire frequency at the flank, and the intermediate layer at the flank and cutting edge portion had the highest peak in the inclination angle section within the range of 0 to 10 degrees, The inclination angle number distribution graph in which the total of the frequencies existing in the range of 10 degrees occupies a ratio of 45% or more of the whole frequency in the inclination angle number distribution graph,
(E) The upper layer in the rake face has the highest peak in the inclination angle section within the range of 0 to 10 degrees, and the total of the frequencies existing in the range of 0 to 10 degrees is the inclination angle number distribution graph. Accounted for 30% or more and less than 60% of the entire frequency at the flank, and the upper surface of the flank and cutting edge portion had the highest peak in the inclination angle section within the range of 0 to 10 degrees, The inclination angle number distribution graph in which the total of the frequencies existing within the range of 10 degrees occupies a ratio of 60% or more of the entire frequency in the inclination angle number distribution graph,
(F) In addition, the upper layer of the (c), when organized observed with a field emission scanning electron microscope, multilateral shape in a plane perpendicular to the thickness direction, in a plane parallel to the thickness direction A Zr-containing aluminum oxide layer having a textured structure composed of crystal grains having a long shape in the layer thickness direction,
(G) Further, the upper layer of (c) is irradiated with an electron beam on each crystal grain existing within the measurement range of the surface polished surface using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. , Measure the angle at which each normal of the crystal lattice plane composed of hexagonal crystal lattice intersects the normal of the substrate surface, and from this measurement result, calculate the crystal orientation relationship between adjacent crystal lattices, Calculate the distribution of lattice points (constituent atom shared lattice points) where each constituent atom shares one constituent atom between the crystal lattices, and do not share constituent atoms between the constituent atom shared lattice points N (however, N is an even number of 2 or more due to the crystal structure of the corundum hexagonal close-packed crystal, but when the upper limit of N is 28 from the point of distribution frequency, 4, 8, 14, 24 and 26) (There is no even number) When the child point form is represented by ΣN + 1, the crystal grains constituting the upper layer of the above (c) on the rake face have an area ratio of 35% or more and less than 60% of the inside of the crystal grains. It is divided by the crystal lattice interface composed of the constituent atomic shared lattice points represented by Σ3, and the area ratio of the crystal grains constituting the upper layer of the above (c) in the flank and the cutting edge is 60 in area ratio. The inside of the crystal grains of at least% is a Zr-containing aluminum oxide layer separated by a crystal lattice interface composed of at least one constituent atom shared lattice point represented by Σ3.
A surface-coated cutting tool characterized by that.
(2) the in the case of the upper layer of (c) organized observed with a field emission scanning electron microscope, hexagonal shape in a plane perpendicular to the thickness direction, the layer thickness in a plane parallel to the thickness direction The surface-coated cutting tool according to (1), wherein the crystal grains having a long shape in the direction occupy an area ratio of 35% or more of the whole in a plane perpendicular to the layer thickness direction. "
It has the characteristics.

Below, the constituent layer of the hard coating layer of the coated tool of this invention is demonstrated in detail.
(A) Ti compound layer (lower layer)
Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer, carbonate (hereinafter referred to as TiCO) layer and carbonitriding A Ti compound layer composed of one or more of the material (hereinafter referred to as TiCNO) layers can be formed by chemical vapor deposition, and basically a modified α-type Al ₂ O ₃ that is an intermediate layer. It exists as a lower layer of the layer and contributes to improving the high-temperature strength of the hard coating layer by its excellent toughness and wear resistance, and it is firmly attached to both the tool base and the modified α-type Al ₂ O ₃ layer It has an action that contributes to improving the adhesion of the hard coating layer to the tool substrate, but if the total average layer thickness is less than 2 μm, the above-mentioned action cannot be sufficiently exerted, whereas the total average layer When the thickness exceeds 15 μm, Heating and mechanical high load during cutting is easily cause thermal plastic deformation in a high-speed heavy cutting conditions acting on, this is because the cause of the uneven wear, defining a total average layer thickness thereof and 2 to 15 [mu] m.

(B) Laser treatment:
In the present invention, after the Ti compound layer (lower layer) is formed, the film forming process is temporarily interrupted, the Ti compound layer (lower layer) formed on the rake face is subjected to laser treatment, and the flank surface As a result of the intentional formation of irregularities on the Ti compound layer (lower layer) and the formation of an intermediate layer and an upper layer thereon, the flank face subjected to laser treatment is It was confirmed that the peel resistance and the wear resistance can be improved. At that time, when the surface roughness of the lower layer subjected to the laser treatment was measured, it was Ra ≧ 0.3 (μm).
Specific laser processing is performed as follows, for example.
The rake face coated with the Ti compound layer (lower layer) is irradiated with laser, and the laser is scanned and irradiated linearly so that the interval between the scanning lines is constant.
At this time, the cross-sectional intensity of the laser beam is a Gaussian distribution with a wavelength of 190 to 360 nm, and the cross-sectional shape of the beam is an ellipse flattened in the scanning direction. That is, this shape is an elliptical shape in which the scanning direction is the short axis and the direction orthogonal to the scanning direction is the long axis. The major axis / minor axis ratio of the ellipse is set to 1.5 or more, and the overlap of the scanning lines is set to ¼ to ３ of the major axis diameter. The peak power density of the laser beam to be scanned is 0.8 to 1.5 MW / cm ² .
At this time, scanning is performed at a speed that satisfies the following relationship with respect to the laser repetition frequency and 1/4 to 1/3 of the scanning direction (short axis length).
Scanning speed [mm / sec]
= (1/3> scanning direction diameter> 1/4 [μm]) / (1 / repetition frequency [Hz])
Moreover, the surface roughness Ra as used in this invention means the value of arithmetic mean roughness Ra prescribed | regulated by JISB0601 (1994), and the measuring method is not specifically limited.

In the present invention, only the Ti compound layer (lower layer) surface of the rake face is subjected to the above laser treatment, and after the surface roughness Ra is set to Ra ≧ 0.3 (μm), the film forming process is resumed, When the intermediate layer and the upper layer are formed thereon, the crystal orientation of the intermediate layer on the rake face, the crystal orientation of the upper layer, and the Σ3 form can be made different from those of the flank and cutting edge. As a result, it is possible to improve the peel resistance and wear resistance of the hard coating layer on the rake face.
As a result, even in high-speed heavy cutting of high hardness steel with high heat generation, a coated tool with excellent flank and cutting edge wear resistance and improved rake face peeling resistance and wear resistance can be obtained. Can be obtained.

(C) α-type Al ₂ O ₃ layer (intermediate layer)
The intermediate layer composed of the α-type Al ₂ O ₃ layer is formed on the lower layer composed of the Ti compound layer, for example, the chemical vapor deposition conditions described in Patent Document 1, that is,
With normal chemical vapor deposition equipment,
Reaction gas composition:% by volume, AlCl ₃ : 3 to 10%, CO ₂ : 0.5 to 3%, C ₂ H ₄ : 0.01 to 0.3%, H ₂ : remaining,
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 3 to 13 kPa,
Under these conditions, Al ₂ O ₃ nuclei are formed on the surface of the Ti compound layer as the lower layer. In this case, the Al ₂ O ₃ nuclei are Al ₂ O ₃ nuclei thin films having an average layer thickness of 20 to 200 nm. Desirably, subsequently, the reaction atmosphere is changed to a hydrogen atmosphere of pressure: 3 to 13 kPa, and the reaction atmosphere temperature is raised to 1100 to 1200 ° C., and the Al ₂ O ₃ core thin film is subjected to heat treatment in the α-type. It can be formed by depositing an Al ₂ O ₃ layer.
In the present invention, the lower layer of the rake face is subjected to laser treatment, and the surface roughness Ra is set to 0.3 (μm) or more, whereby the rake face is different from the flank face and the cutting edge part. An α-type Al ₂ O ₃ layer having crystal orientation is formed.
That is, with respect to the flank and the cutting edge α-type Al ₂ O ₃ layer chemically vapor-deposited on the Ti compound layer (lower layer), a field emission scanning electron microscope is used, and FIGS. As shown in FIG. 1, the crystal grains having a hexagonal crystal lattice existing within the measurement range of the surface polished surface are irradiated with an electron beam, and the crystal plane of the crystal grains is compared with the normal line of the surface polished surface. An inclination angle formed by a normal line of a (0001) plane is measured, and among the measurement inclination angles, a measurement inclination angle within a range of 0 to 45 degrees is divided for each pitch of 0.25 degrees. In the case of an inclination angle distribution graph obtained by summing up the frequencies existing in the area, as illustrated in FIG. 2, a sharp maximum peak appears in the range of the inclination angle section 0 to 10 degrees, and the inclination angle section 0 The sum of the frequencies existing in the range of -10 degrees is the frequency in the tilt angle frequency distribution graph. It accounts for over 45% of the total.
On the other hand, for the intermediate layer (α-type Al ₂ O ₃ layer) formed on the rake face, the sum of the frequencies existing in the range of the tilt angle section 0 to 10 degrees is as shown in FIG. It is 20% or more and less than 45% of the entire frequency in the number distribution graph.
Therefore, the intermediate layer of the flank and cutting edge is configured as an α-type Al ₂ O ₃ layer having a high (0001) plane orientation ratio, but the (0001) plane orientation ratio of the rake face is the flank and cutting edge. Since it is kept low relative to the part, the adhesion strength between the lower layer and the intermediate layer is increased on the rake face, and this intermediate layer exhibits excellent high-temperature hardness, heat resistance, and high-temperature strength. In addition, since the adhesion strength with the Zr-containing α-type Al ₂ O ₃ layer deposited on this layer is also increased, as a result, the peeling resistance and wear resistance of the hard coating layer on the rake face are improved. Can do.
As for the average layer thickness of the intermediate layer composed of the α-type Al ₂ O ₃ layer, the above characteristics are obtained when the average layer thickness of the intermediate layer is less than 1 μm in any of the rake face, flank face, and cutting edge part. On the other hand, if the average thickness of the hard coating layer cannot exceed 5 μm, thermoplastic deformation that causes uneven wear is likely to occur due to high heat generated at the time of cutting, which accelerates wear. Therefore, the average layer thickness was determined to be 1 to 5 μm.

(D) Zr-containing α-type Al ₂ O ₃ layer (upper layer)
In the upper layer composed of the Zr-containing α-type Al ₂ O ₃ layer formed by chemical vapor deposition on the intermediate layer, the constituent Al component improves the high-temperature hardness and heat resistance of the layer. The Zr component contained in a small amount (Zr / (Al + Zr) in a ratio of the total amount with Al of 0.002 to 0.01 (atomic ratio)) is contained in the Zr-containing α-type Al ₂ O ₃ layer. Although the crystal grain interface strength is improved and contributes to the improvement of the high temperature strength, when the content ratio of the Zr component is less than 0.002, the above effect cannot be expected, while the content ratio of the Zr component is 0.01. In the case of exceeding ZrO ₂ particles precipitated in the layer, the grain interface strength decreases, so the content ratio of the Zr component in the total amount with the Al component (Zr / (Al + Zr) ratio value) Is within the range of 0.002 to 0.01 (atomic ratio) Masui.

the Zr-containing α-type the Al ₂ O ₃ layer formed on the intermediate layer consisting of α-type Al ₂ O ₃ layer is the reaction gas composition during the deposition, each chemical vapor deposition conditions of reaction atmosphere temperature and reaction atmosphere pressure, e.g. The film can be formed by adjusting as follows.
That is, first,
(B) Reaction gas composition (volume%):
AlCl ₃ : 1 to 5%,
ZrCl _4: 0.05~0.1%,
CO ₂ : 2-6%,
HCl: 1-5%,
H ₂ S: 0.25~0.75%,
H ₂ : Remaining
(B) Reaction atmosphere temperature; 1020 to 1050 ° C.,
(C) Reaction atmosphere pressure; 3-5 kPa,
After performing the first stage deposition for about 1 hour under the conditions of
next,
(B) Reaction gas composition (volume%):
AlCl ₃ : 6 to 10%,
ZrCl _4: 0.6~1.2%,
CO _2: 4~8%,
HCl: 3-5%,
H ₂ S: 0.25~0.6%,
H ₂ : Remaining
(B) Reaction atmosphere temperature; 920 to 1000 ° C.,
(C) Reaction atmosphere pressure; 6 to 10 kPa,
When the vapor deposition layer having an average layer thickness of 2 to 15 μm is formed by performing the second stage vapor deposition under the conditions, the ratio value of Zr / (Al + Zr) is 0.002 to 0.01 in atomic ratio. A Zr-containing α-type Al ₂ O ₃ layer can be formed.

In the present invention, the intermediate layer of the rake face showed a crystal orientation different from that of the flank and cutting edge as described above, but the upper layer of the rake face and the flank and cutting edge of the upper layer were also The crystal orientation was different from that of the upper layer.
That is, a crystal having a hexagonal crystal lattice existing within the measurement range of the surface polished surface using a field emission scanning electron microscope for the flank and the upper layer (Zr-containing α-type Al ₂ O ₃ layer) of the cutting edge portion Each grain is irradiated with an electron beam, and an inclination angle formed by a normal line of the (0001) plane which is a crystal plane of the crystal grain is measured with respect to a normal line of the surface polished surface, When the measured tilt angle in the range of 0 to 45 degrees is divided into pitches of 0.25 degrees and the frequency existing in each section is tabulated, the tilt angle distribution graph is used to represent the tilt angle. A sharp maximum peak appears in the range of 0 to 10 degrees, and the sum of the frequencies existing in the range of 0 to 10 degrees of the inclination angle accounts for 60% or more of the whole frequency in the inclination angle distribution graph. It was.
On the other hand, for the upper layer (Zr-containing α-type Al ₂ O ₃ layer) formed on the rake face, the total number of frequencies existing in the range of the tilt angle section 0 to 10 degrees is the entire frequency in the tilt angle frequency distribution graph. 30% or more and less than 60%.
Accordingly, the upper layer of the flank face and the cutting edge portion is configured as a Zr-containing α-type Al ₂ O ₃ layer having a high (0001) plane orientation ratio and excellent in high-temperature strength, while the (0001) plane of the upper layer of the rake face. Since the orientation rate is kept low with respect to the flank and cutting edge, an upper layer (Zr-containing α-type Al ₂ O ₃ layer) excellent in peeling resistance and wear resistance is formed on the rake face.

Further, when the structure of the upper layer (Zr-containing α-type Al ₂ O ₃ layer) is observed with a field emission scanning electron microscope, it is seen in a plane perpendicular to the layer thickness direction as shown in FIG. when the a not large multi angle shape of the crystal grain size, also, as shown in FIG. 4 (b), when viewed in a plane parallel to the thickness direction, the layer surface is a substantially flat In addition, a texture structure composed of crystal grains having a long shape in the layer thickness direction (flat polygonal long crystal grains) is formed.
Here, the “vertical length” shape referred to in the present invention is a structure in which the average length (average height) of crystal grains in the layer thickness direction is larger than the average width of crystal grains in the direction perpendicular to the layer thickness direction. Refers to the structure.

In the vapor deposition of the Zr-containing α-type Al ₂ O ₃ layer, more limited conditions (for example, H ₂ S in the reaction gas in the first stage is 0.50 to 0.75 vol%, and the reaction atmosphere temperature is 1020). And ZrCl ₄ in the reaction gas in the second stage is 0.6 to 0.9% by volume, H ₂ S is 0.25 to 0.4% by volume, and the reaction atmosphere temperature is 960 to 980 ° C. 4), the Zr-containing α-type Al ₂ O ₃ layer of the cutting edge portion is viewed in a plane perpendicular to the layer thickness direction, as shown in FIG. a hexagonal shape with a large grain size, and, when viewed in a plane parallel to the thickness direction, similar to that shown in FIG. 4 (b), the layer surface is substantially flat, in the layer thickness direction Structure in which crystal grains having a long shape occupy an area ratio of 35% or more of the whole in a plane perpendicular to the layer thickness direction Is formed.

Further, the Zr-containing α-type Al ₂ O ₃ layer was irradiated with an electron beam on each crystal grain existing within the measurement range of the surface polished surface using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. Measuring the angle at which each normal of the crystal lattice plane consisting of hexagonal crystal lattice intersects the normal of the surface polished surface,
From this measurement result, the crystal orientation relationship between adjacent crystal lattices is calculated, and each of the constituent atoms constituting the crystal lattice interface shares one constituent atom between the crystal lattices (constituent atom shared lattice point). ) And the number of lattice points that do not share constituent atoms between the constituent atomic shared lattice points (where N is an even number of 2 or more on the crystal structure of the corundum hexagonal close-packed crystal, but the distribution frequency) When the upper limit of N is 28 from this point, the even number of 4, 8, 14, 24 and 26 does not exist.)
As shown in FIG. 6, the flank and the upper layer of the cutting edge are flat plate polygons (including flat hexagons) constituting the Zr-containing α-type Al ₂ O ₃ layer observed with a field emission scanning electron microscope. ) It can be seen that the length of 60% or more of the long-shaped crystal grains is divided by at least one Σ3-compatible interface, and the upper layer of the rake face is In addition, the inside of flat polygonal (including flat hexagonal) long crystal grains having an area ratio of 35% or more and less than 60% is divided by at least one Σ3-compatible interface. I understand that.
Further, the presence of the above-described Σ3-compatible interface inside the Zr-containing α-type Al ₂ O ₃ layered flat polygonal (including flat hexagonal) long crystal grains improves the strength within the grains. As a result, during high-speed heavy cutting of high-hardness steel, cracks are suppressed from occurring in the Zr-containing α-type Al ₂ O ₃ layer on the flank and cutting edge, and cracks are also temporarily generated. Even so, crack growth and propagation are hindered, and chipping resistance is improved.

In addition, regarding the average layer thickness of the upper layer made of the Zr-containing α-type Al ₂ O ₃ layer, not only the flank and cutting edge but also the rake surface, the upper layer has an average layer thickness of less than 2 μm. The excellent properties of the layer cannot be fully exhibited. On the other hand, if the average layer thickness of the upper layer exceeds 15 μm, thermoplastic deformation that causes uneven wear is likely to occur, and chipping is also likely to occur. Therefore, the average layer thickness of the upper layer was determined to be 2 to 15 μm.

As described above, the coated tool of the present invention has a high (0001) plane orientation ratio of the intermediate layer coated on the flank and cutting edge, and has excellent high-temperature strength and heat resistance, while being coated on the rake face. The intermediate layer has a low (0001) plane orientation ratio relative to the flank and cutting edge, but has excellent adhesion strength with the lower layer, and the upper part of the cutting edge, rake face and flank. The Zr-containing α-type Al ₂ O ₃ layer constituting the layer has a textured structure composed of long and flat crystal grains (including flat hexagons) having surface flatness. A Zr-containing α-type Al ₂ O ₃ layer that has superior surface properties and high-temperature strength by forming a Σ3-compatible interface inside and strengthening the strength within the crystal grains, and further constituting the upper layer of the rake face Has high adhesion strength to the intermediate layer and excellent peeling resistance and wear resistance Since the Zr-containing α-type Al ₂ O ₃ layer on the flank face and the cutting edge portion has excellent wear resistance and chipping resistance, the coated tool formed with such a hard coating layer has high heat generation and mechanical properties. Even in high-speed heavy cutting of high-hardness steel with high loads, excellent chipping resistance on the rake face and cutting edge surface, wear resistance, excellent peeling resistance on the flank face, and wear resistance Further, the service life can be further extended.

It is a schematic diagram illustrating a measurement range of the inclination angle in the case of measuring the (0001) plane crystal grains of the α-type the Al ₂ O ₃ layer constituting the hard coating layer. It is an inclination angle number distribution graph of the (0001) plane of the α-type Al ₂ O ₃ layer constituting the intermediate layer of the cutting edge portion of the coated tool 3 of the present invention. It is an inclination angle number distribution graph of the (0001) plane of the α-type Al ₂ O ₃ layer constituting the intermediate layer of the rake face of the coated tool 3 of the present invention. (A) is obtained by observing the upper layer composed of the Zr-containing α-type Al ₂ O ₃ layer of the cutting edge portion of the coated tool 2 of the present invention with a field emission scanning electron microscope in a plane perpendicular to the layer thickness direction. was a schematic diagram showing a grain structure structure of multilateral shape, (b), like, obtained by observation with a field emission scanning electron microscope in a plane parallel to the thickness direction, the layer surface Is a schematic view showing a grain structure having a long shape in the layer thickness direction, and (c) is a Zr-containing α-type Al ₂ O ₃ of the cutting edge portion of the coated tool 11 of the present invention. for the upper layer comprising a layer, obtained by observation with a field emission scanning electron microscope in a plane perpendicular to the thickness direction is a schematic view showing a grain structure structure of hexagonal shape. (A) is obtained by observing the upper layer composed of the Zr-containing α-type Al ₂ O ₃ layer on the rake face of the coated tool 2 of the present invention with a field emission scanning electron microscope in a plane perpendicular to the layer thickness direction. and is a schematic diagram showing a grain structure structure of multilateral shape and (b), like, obtained by observation with a field emission scanning electron microscope in a plane parallel to the thickness direction, the layer surface It is a schematic diagram showing a crystal grain structure structure which is almost flat and has a long shape in the layer thickness direction, and (c) is a view from a Zr-containing α-type Al ₂ O ₃ layer on the rake face of the coated tool 11 of the present invention. for top layer consisting, obtained by observation with a field emission scanning electron microscope in a plane perpendicular to the thickness direction is a schematic view showing a grain structure structure of hexagonal shape. (A), (b), respectively, the upper layer consisting of Zr-containing α-type the Al ₂ O ₃ layer of the cutting portion of the present invention coated tool 2, a field emission scanning electron microscope and an electron backscatter diffraction image device was measured using a grain boundary analysis diagram of the plane perpendicular to the thickness direction, the solid line indicates the grain boundaries of the multi-angle shape that is observed by a field emission scanning electron microscope and a broken line, electron back scattering diffraction The Σ3-corresponding interface in the crystal grain measured by the image device is shown. It is a schematic diagram showing a rake face, a flank face, and a cutting edge portion of a coated tool, and a hatched portion shown in the drawing (a straight line is drawn from the rake face and the flank face, and the straight line and the corner R end of the tool base, the thickness from the contact The portion surrounded by the depth direction) is the cutting edge portion. However, when the corner R of the tool base is zero, the double hatched portion shown in the figure (the portion surrounded by the film thickness depth direction from the intersection of the rake face and the straight line drawn from the flank face) is the cutting edge portion.

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

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 2 to 4 μm are prepared as raw material powders. These raw material powders were blended into the composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact with a predetermined shape at a pressure of 98 MPa. The green compact was vacuum sintered at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa. After sintering, the cutting edge portion was R: 0.07 mm honing By processing, tool bases A to E made of a WC-based cemented carbide having a throwaway tip shape defined in ISO · CNMG120408 were produced.

In addition, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder, all having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and pressed into a compact at a pressure of 98 MPa. The green compact was 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 was subjected to a honing process of R: 0.07 mm. Tool bases a to e made of TiCN base cermet having a standard / CNMG120408 chip shape were formed.

Then, each of these tool bases A to E and tool bases a to e is charged into a normal chemical vapor deposition apparatus,
(A) First, Table 3 (l-TiCN in Table 3 indicates the conditions for forming a TiCN layer having a vertically elongated crystal structure described in JP-A-6-8010, and the other conditions are ordinary granularity. Under the conditions shown in Table 6), the Ti compound layer having the target layer thickness shown in Table 6 is deposited as the lower layer of the hard coating layer,
(B) Next, the Ti compound layer (lower layer) having the surface roughness shown in Table 7 is formed without performing laser treatment on the Ti compound layer (lower layer) on the flank and cutting edge. The Ti compound layer (lower layer) on the rake face is subjected to laser treatment to form a Ti compound layer (lower layer) having the surface roughness shown in Table 8,
(C) Next, an Al ₂ O ₃ core thin film was formed on the Ti compound layer (lower layer) under the conditions shown in Table 4, and then subjected to heat treatment, under the conditions shown in Table 3. 7, an intermediate layer composed of an α-type Al ₂ O ₃ layer having a target layer thickness shown in Table 8 is formed by vapor deposition on the cutting edge, rake face, and flank face,
(D) Next, under the vapor deposition conditions shown in Table 5, the Zr-containing α-type Al ₂ O ₃ layer having the target layer thickness shown in Tables 7 and 8 is formed as the upper layer of the hard coating layer by vapor deposition. The present coated tools 1 to 15 were produced, respectively.
If the laser processing conditions are specifically described, for example, in the coated tool 3 of the present invention, the cross-sectional intensity of the laser beam is Gaussian distributed with a wavelength of 355 nm, and the peak power density of the scanning laser beam is 1.0 MW. / Cm ² and the scanning speed was 1.25 mm / sec. Laser treatment was performed. As a result, a lower layer surface having a surface roughness of 0.35 μm was formed.

Further, for comparison purposes, the lower layer of the hard coating layer is formed under the conditions shown in Table 3, and the Ti compound layer (lower layer) is formed on the conditions shown in Table 4 without performing laser treatment on the lower layer. An intermediate layer composed of an α-type Al ₂ O ₃ layer having a target layer thickness shown in Table 9 under the conditions shown in Table 3 in the state where an Al ₂ O ₃ nuclear thin film is formed on the substrate and then heat-treated. Then, the Zr-containing α-type Al ₂ O ₃ layer having the target layer thickness shown in Table 9 is formed on the upper portion of the hard coating layer according to the deposition conditions shown in Table 5. Comparative coating tool provided with a hard coating layer comprising a Ti compound layer having a target layer thickness shown in Table 9, an α-type Al ₂ O ₃ layer, and a Zr-containing α-type Al ₂ O ₃ layer by vapor deposition as a layer 1 to 15 were produced.
The tool base type, the lower layer type, the lower layer thickness, the intermediate layer thickness, and the upper layer thickness of the comparative coated tools 1 to 15 are the same as those of the inventive coated tools 1 to 15, respectively.

Table 7 shows the surface roughness of the Ti compound layer (lower layer) of the flank face and the cutting edge part of the inventive coated tools 1 to 15 that were not subjected to laser treatment, and Table 8 shows the inventive coating. The surface roughness of the rake face Ti compound layer (lower layer) whose surface is roughened by laser processing of the tools 1 to 15 is shown.
Table 9 also shows the surface roughness Ra of the lower layer of the comparative coated tools 1 to 15 not subjected to laser treatment for reference.

Subsequently, the α-type Al ₂ O ₃ layer constituting the intermediate layer of the hard coating layer of the present invention-coated tools 1 to 15 and the comparative coated tools 1 to 15 and the Zr-containing α-type Al ₂ O ₃ constituting the upper layer. About the layer, the inclination angle number distribution graph was each created using the field emission scanning electron microscope.
That is, the inclination angle number distribution graph shows the column of the field emission scanning electron microscope with the respective surfaces of the present invention coated tools 1 to 15 and comparative coated tools 1 to 15 being polished surfaces. A crystal grain having a hexagonal crystal lattice existing in the measurement range of each surface polished surface with an electron beam with an acceleration voltage of 15 kV and an irradiation current of 1 nA at an incident angle of 70 degrees on the polished surface. Individually irradiated, using an electron backscatter diffraction image apparatus, a region of 30 × 50 μm at a spacing of 0.1 μm / step is a crystal plane of the crystal grain with respect to the normal of the polished surface (0001 ) The inclination angle formed by the normal of the surface is measured, and based on the measurement result, the measurement inclination angle within the range of 0 to 45 degrees of the measurement inclination angles is divided for each pitch of 0.25 degrees. As well as the frequencies present in each category By aggregate was prepared inclination angle frequency distribution graph.
As an example of the inclination angle number distribution graph, FIG. 2 shows an inclination angle number distribution graph of the (0001) plane of the α-type Al ₂ O ₃ layer constituting the intermediate layer of the cutting edge portion of the coated tool 3 of the present invention, and FIG. The inclination angle number distribution graph of the (0001) plane of the α-type Al ₂ O ₃ layer constituting the intermediate layer of the rake face of the coated tool 3 of the present invention is shown.
The “surface” in the present invention includes not only a surface parallel to the substrate surface but also a surface inclined with respect to the substrate surface, for example, a cut surface of a layer.

In Table 7 to Table 9, in the inclination angle number distribution graphs of the α-type Al ₂ O ₃ layer and the Zr-containing α-type Al ₂ O ₃ layer of the inventive coated tools 1 to 15 and the comparative coated tools 1 to 15, The ratio of the frequency existing in the tilt angle section within the range of 10 degrees to the entire tilt angle number distribution graph is shown.
As is clear from Tables 7 and 8, in the flank and cutting edge of the coated tools 1 to 15 of the present invention, the frequency ratio existing in the inclination angle section within the range of 0 to 10 degrees in the inclination angle number distribution graph. is alpha-type Al ₂ O 45% or more in _three layers, also whereas the Zr-containing alpha-type the Al ₂ O ₃ layer is 60% or more, in the rake face of the present invention coated tool 15 is inclined power ratio existing in the tilt angle sections of the range of 0 ° in the angular frequency distribution graph is less than 20-45% in α-type the Al ₂ O ₃ layer, and in Zr-containing α-type the Al ₂ O ₃ layer is 30 It was less than -60%.
In addition, as shown in Table 9, in the comparative coating tools 1 to 15, the inclination angle division within the range of 0 to 10 degrees in the inclination angle number distribution graph for any of the cutting edge portion, the rake face, and the flank face The frequency ratio existing in the α-type Al ₂ O ₃ layer was 45% or more, and the Zr-containing α-type Al ₂ O ₃ layer was 60% or more.

Next, a field emission scanning electron microscope and an electron backscatter diffraction image apparatus are used for the Zr-containing α-type Al ₂ O ₃ layer constituting the upper layer of the present invention coated tools 1 to 15 and comparative coated tools 1 to 15. Thus, the grain structure and the constituent atom shared lattice point morphology were investigated.
That is, first, the Zr-containing α-type Al ₂ O ₃ layers of the flank and cutting edge of the above-described inventive coated tools 1 to 15 and comparative coated tools 1 to 15 were observed using a field emission scanning electron microscope. However, in the coated tools 1 to 15 of the present invention, a crystal grain structure having a large grain size that is a flat plate polygon (including a flat hexagon) and a long and long shape typically shown in FIGS. 4 (a) and 4 (b). The structure was observed (Note that FIG. 4A is a schematic diagram of the structure of the coated tool 2 of the present invention viewed in a plane perpendicular to the layer thickness direction, and FIG. 4C is a diagram in the layer thickness direction. of the present invention coated tool 11 as viewed in a plane perpendicular, hexagonal shape and freshly length tissue schematic structure consisting of large particle size of the crystal grain shape).
Moreover, the crystal grain structure similar to the case of this invention was observed also about the flank and cutting edge part of the comparative coating tools 1-15.

Next, a Σ3-compatible interface is formed inside the crystal grains constituting the Zr-containing α-type Al ₂ O ₃ layer of the cutting edge portion, rake face, and flank face of the above-described inventive coated tools 1-15 and comparative coated tools 1-15. The area ratio of the crystal grains in which there was was measured.
First, with respect to the Zr-containing α-type Al ₂ O ₃ layer on each of the cutting edge, rake face, and flank face of the coated tools 1 to 15 of the present invention, a field emission scanning electron microscope in a state where the surface is a polished surface. A hexagonal crystal lattice existing in the measurement range of each surface polished surface at an irradiation current of 1 nA with an acceleration voltage of 15 kV at an incident angle of 70 degrees on the surface polished surface. Each of the crystal grains having the crystal grains is irradiated with an electron beam, and a normal line of each crystal lattice plane of the crystal grains is formed at an interval of 0.1 μm / step in an area of 30 × 50 μm using an electron backscatter diffraction image apparatus. Is measured from the measurement results, the crystal orientation relationship between adjacent crystal lattices is calculated from the measurement results, and each of the constituent atoms constituting the crystal lattice interface is one between the crystal lattices. Lattice points that share constituent atoms (configuration The distribution of atomic shared lattice points is calculated, and N lattice points that do not share constituent atoms between the constituent atomic shared lattice points (where N is an even number of 2 or more in the crystal structure of the corundum hexagonal close-packed crystal) However, when the upper limit of N is 28 from the point of distribution frequency, there is no even number of 4, 8, 14, 24, and 26) When the existing constituent atom shared lattice point form is represented by ΣN + 1, Zr content Among all the crystal grains existing within the measurement range of the α-type Al ₂ O ₃ layer, the area ratio of the crystal grains in which at least one Σ3 corresponding interface exists in the crystal grains is obtained, Tables 7 and 8 show the Σ3 corresponding interface ratio (%).
Further, the comparison coated tool 15 also optionally the same method of the present invention coated tools, among all crystal grains existing within the measuring range of the Zr-containing α-type the Al ₂ O ₃ layer, the interior of the crystal grains In addition, the area ratio of crystal grains in which at least one Σ3-corresponding interface exists was determined, and the value is shown in Table 9 as the Σ3-compatible interface ratio (%).
The Σ3-corresponding interface ratio calculates the area of each crystal grain by color-identifying each crystal grain existing within the measurement range (30 × 50 μm). Calculate by dividing the area of the crystal grains where there are two or more Σ3-corresponding interfaces by the total area of all the crystal grains, and calculate the average value of the five measurement ranges determined by the above calculation method. It was defined as a percentage (%).

As shown in Tables 7 and 8, the Zr-containing α-type Al ₂ O ₃ layer of the flank and cutting edge of the coated tools 1 to 15 of the present invention has at least one Σ3-compatible interface inside the crystal grains. The area ratio of the crystal grains in which at least one Σ3 corresponding interface exists in the crystal grain is 35% or more and 60%. It can be seen that the ratio of the interface corresponding to Σ3 in the crystal grains is small.
Further, as shown in Table 9, for the comparative coated tools 1 to 15, at least one Σ3 corresponding interface exists in the crystal grains for any of the cutting edge portion, the rake face, and the flank face. The area ratio of the crystal grains was 60% or more.

Further, the Zr-containing α-type Al ₂ O ₃ layer of the cutting edge, flank and rake face of the present coated tools 1 to 15 and the Zr-containing α of the cutting edge, flank and rake face of the comparative coated tools 1 to 15 are used. The area ratio of large hexagonal flat hexagonal crystal grains present in a plane perpendicular to the layer thickness direction was determined for the type Al ₂ O ₃ layer using a field emission scanning electron microscope. This value is shown in Tables 7-9.
In addition, the crystal grains of the “large hexagonal flat hexagonal shape” mentioned here are:
“The diameter of particles existing in a plane perpendicular to the layer thickness direction observed by a field emission scanning electron microscope is measured, the average value of 10 particles is 3 to 8 μm, and the vertex angle is 100 to 140 °. It is a polygonal shape with six apex angles. "
It is defined as

  Next, the thickness of each constituent layer of the hard coating layer of the present invention coated tool 1-15, comparative coated tool 1-15 was measured using a scanning electron microscope (longitudinal cross section measurement), in either case, The average layer thickness (average value of 5-point measurement) substantially the same as the target layer thickness was shown.

Next, for the above-described inventive coated tools 1-15 and comparative coated tools 1-15, both are screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SUJ2 (HRC62) round bar,
Cutting speed: 250 m / min. ,
Incision: 2.7 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 5 minutes,
Dry high-speed heavy cutting test of bearing steel under the following conditions (referred to as cutting condition A) (normal cutting speed and infeed are 200 m / min and 1.5 mm, respectively),
Work material: JIS · SKD11 (HRC58) round bar,
Cutting speed: 300 m / min. ,
Incision: 2.7 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 5 minutes,
Dry high-speed heavy cutting test of alloy tool steel under the following conditions (referred to as cutting condition B) (normal cutting speed and infeed are 200 m / min. And 1.5 mm, respectively),
Work material: JIS / SK3 (HRC61) round bar,
Cutting speed: 250 m / min. ,
Incision: 2.7 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 5 minutes,
Dry high-speed heavy cutting test of carbon tool steel under the following conditions (referred to as cutting condition C) (normal cutting speed and infeed are 150 m / min. And 1.5 mm, respectively),
In each cutting test, the amount of wear of the hard coating layer on the flank and the presence or absence of peeling were measured and observed.
The measurement results are shown in Table 10.

From the results shown in Tables 7 to 10, according to the present invention coated tools 1 to 15, α-type Al ₂ O showing a high ratio of (0001) plane orientation ratio of 45% or more as an intermediate layer of the flank and cutting edge. _Three layers are formed, and an upper layer composed of a Zr-containing α-type Al ₂ O ₃ layer is formed thereon, and the upper layer is a flat polygonal (flat hexagonal) elongated crystal grain structure It has a structure, and the (0001) plane orientation ratio is as high as 60% or higher, and the crystal grain area ratio in which at least one Σ3-compatible interface exists inside the crystal grains is as high as 60% or higher. Thus, the Zr-containing α-type Al ₂ O ₃ layer has excellent high-temperature strength and in-grain strength, and also has excellent surface flatness, and on the other hand, from the rake face Ti compound layer The surface of the lower layer is made laser-treated so that its surface roughness Ra is 0 3 is textured such that ([mu] m) or more, as a result, (0001) plane orientation ratio of the rake face is in the α-type the Al ₂ O ₃ layer is reduced to less than 45% or more 20%, Zr-containing α-type Al _{In the 2} O ₃ layer, the crystal grain size is reduced to 30% or more and less than 60%, and in addition, at least one Σ3 corresponding interface exists inside the crystal grain of the Zr-containing α-type Al ₂ O ₃ layer on the rake face. By reducing the area ratio to 35% or more and less than 60%, high-speed heavy cutting of hardened steel such as alloy tool steel and bearing steel hardened material with high heat generation, hard covering of the flank and cutting edge The layer exhibits excellent high-temperature strength, wear resistance, and chipping resistance, as well as excellent cutting performance over a long period of use by further improving the peel resistance and wear resistance of the hard coating layer on the rake face. Shows further extension of service life And it makes it possible to.
On the other hand, the comparative coated tools 1 to 15 in which the same hard coating layer is formed on any of the cutting edge portion, the rake face, and the flank face have high hardness such as a hardened material of alloy tool steel or bearing steel. In high-speed heavy cutting of steel, it is clear that the service life can be reached in a relatively short time, particularly due to the occurrence of peeling of the hard coating layer on the rake face and the reduction in wear resistance.

  As described above, the coated tool of the present invention is capable of chipping not only in normal conditions such as various steels and cast iron, but also in high-speed heavy cutting of high-hardness steel with high heat generation and high mechanical load. Since it exhibits excellent peeling resistance and wear resistance without any occurrence, and exhibits excellent cutting performance over a long period of time, it is possible to improve the performance of cutting equipment, reduce the labor and energy of cutting, and reduce costs. It is possible to cope with the conversion sufficiently satisfactorily.

Claims (2)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) the lower layer is formed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer, all formed by chemical vapor deposition; And a Ti compound layer having a total average layer thickness of 2 to 15 μm,
(B) the intermediate layer has an average layer thickness of 1 to 5 μm, and an aluminum oxide layer having an α-type crystal structure in the state of chemical vapor deposition;
(C) the upper layer has an average layer thickness of 2 to 15 μm, and a Zr-containing aluminum oxide layer having an α-type crystal structure in a chemical vapor deposited state;
In the surface-coated cutting tool in which the hard coating layer composed of the above (a) to (c) is formed by vapor deposition,
For the intermediate layer of (b) and the upper layer of (c), each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface of the tool base is measured using a field emission scanning electron microscope. Irradiated with an electron beam, the inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal line of the surface-polished surface. When the measured inclination angle within the range of 45 degrees is divided for each pitch of 0.25 degrees and the frequency existing in each division is represented by an inclination angle number distribution graph,
(D) The intermediate layer in the rake face has the highest peak in the inclination angle section within the range of 0 to 10 degrees, and the total of the frequencies existing in the range of 0 to 10 degrees is the inclination angle number distribution graph. Accounted for 20% or more and less than 45% of the entire frequency at the flank, and the intermediate layer at the flank and cutting edge portion had the highest peak in the inclination angle section within the range of 0 to 10 degrees, An inclination angle number distribution in which the sum of the frequencies existing within a range of 10 degrees occupies a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution graph,
(E) The upper layer in the rake face has the highest peak in the inclination angle section within the range of 0 to 10 degrees, and the total of the frequencies existing in the range of 0 to 10 degrees is the inclination angle number distribution graph. The upper layer in the flank and cutting edge portion has the highest peak in the inclination angle section in the range of 0 to 10 degrees, and the above 0 to 10 The inclination angle number distribution graph in which the total of the frequencies existing in the range of degrees occupies a ratio of 60% or more of the whole frequency in the inclination angle number distribution graph,
(F) In addition, the upper layer of the (c), when organized observed with a field emission scanning electron microscope, multilateral shape in a plane perpendicular to the thickness direction, in a plane parallel to the thickness direction A Zr-containing aluminum oxide layer having a textured structure composed of crystal grains having a long shape in the layer thickness direction,
(G) Further, with respect to the upper layer of (c), an electron beam is irradiated to each crystal grain existing within the measurement range of the surface polished surface using a field emission scanning electron microscope and an electron backscatter diffraction image apparatus. , Measure the angle at which each normal of the crystal lattice plane composed of hexagonal crystal lattice intersects the normal of the substrate surface, and from this measurement result, calculate the crystal orientation relationship between adjacent crystal lattices, Calculate the distribution of lattice points (constituent atom shared lattice points) where each constituent atom shares one constituent atom between the crystal lattices, and do not share constituent atoms between the constituent atom shared lattice points N (however, N is an even number of 2 or more due to the crystal structure of the corundum hexagonal close-packed crystal, but when the upper limit of N is 28 from the point of distribution frequency, 4, 8, 14, 24 and 26) (There is no even number) When the shared lattice point form is represented by ΣN + 1, at least one of the crystal grains constituting the upper layer of the above (c) on the rake face has an area ratio of 35% or more and less than 60%. Is divided by a crystal lattice interface composed of a constituent atomic shared lattice point represented by Σ3, and the area ratio among the crystal grains constituting the upper layer of (c) above in the cutting edge portion and the flank face The interior of 60% or more of the crystal grains is a Zr-containing aluminum oxide layer separated by a crystal lattice interface composed of at least one constituent atom shared lattice point represented by Σ3.
A surface-coated cutting tool characterized by that. When the upper layer of the (c) organized observed with a field emission scanning electron microscope, hexagonal shape in a plane perpendicular to the thickness direction, also the layer thickness direction in a plane parallel to the thickness direction The surface-coated cutting tool according to claim 1, wherein the crystal grains having a long shape occupy an area ratio of 35% or more of the whole in a plane perpendicular to the layer thickness direction.

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