JP4569861B2 - Surface coated cermet cutting tool with excellent chipping resistance with hard coating layer - Google Patents

Description

  The present invention relates to a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool) that exhibits excellent chipping resistance with a hard coating layer, particularly in high-speed intermittent cutting of steel or 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) As a lower layer, a Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer formed by chemical vapor deposition, Ti compound layer comprising one or more of a carbon oxide (hereinafter referred to as TiCO) layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer and having a total average layer thickness of 3 to 20 μm ,
(B) the upper layer has an α-type crystal structure in the state of chemical vapor deposition, and
Composition _{formula: (Al 1-X B X} ) 2 O 3,
("B" in the above composition formula represents boron), the X value is measured by an electron beam microanalyzer (EPMA) and the atomic ratio satisfies 0.001 to 0.01, and 1 A vapor-deposited α-type Al-based oxide [hereinafter referred to as (Al, B) ₂ O ₃ ] layer having an average layer thickness of ˜15 μm;
A coated cermet tool formed by forming a hard coating layer composed of (a) and (b) above is known, and this coated cermet tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is also known that

In general, the Ti compound layer and the vapor-deposited α-type (Al, B) ₂ O ₃ layer constituting the hard coating layer of the above coated cermet tool have a granular crystal structure, and further the TiCN constituting the Ti compound layer For the purpose of improving the strength of the layer itself, the chemical layer is used in a normal chemical vapor deposition apparatus, using a mixed gas containing an organic carbonitride such as CH ₃ CN as a reaction gas at a medium temperature range of 700 to 950 ° C. It is also known to have a vertically grown crystal structure formed by vapor deposition.
JP 58-115081 A Japanese Patent Laid-Open No. 6-8010

In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting work, and along with this, cutting work tends to be further accelerated. For coated cermet tools, there is no problem when this is used for continuous cutting and interrupted cutting under normal conditions such as steel and cast iron. The Ti compound layer, which is the lower layer of the hard coating layer, has high strength and excellent chipping resistance when used for high-speed interrupted cutting with repeated mechanical thermal shock at a very short pitch. The vapor-deposited α-type (Al, B) ₂ O ₃ layer constituting the layer has excellent high temperature hardness and heat resistance due to the constituent Al component, and the B component further improves the high temperature hardness. But Since it does not have sufficient high-temperature strength, it is extremely brittle against mechanical and thermal shocks, which makes it easy for chipping (minute chipping) to occur in the hard coating layer, resulting in a relatively short time. At present, the service life is reached.

In view of the above, the inventors of the present invention intend to improve the chipping resistance of the deposited α-type (Al, B) ₂ O ₃ layer constituting the upper layer of the hard coating layer of the coated cermet tool. As a result of research,
On the surface of the tool base, after forming the Ti compound layer under normal conditions as a lower layer with a normal chemical vapor deposition apparatus, under the same normal conditions,
Also the composition _{formula: (Al 1-X B X} ) 2 O 3,
In this case, the crystal structure is a κ-type or θ-type crystal structure having an X value measured by an electron microanalyzer (EPMA) and having an atomic ratio of 0.001 to 0.01. (Al, B) ₂ O ₃ layer having a vapor deposition is formed on the surface of the (Al, B) ₂ O ₃ layer.
Reaction gas composition: by _{volume%, TiCl 4: 0.2~3%,} CO 2: 0.2~10%, Ar: 5~50%, H 2: remainder,
Reaction atmosphere temperature: 900-1020 ° C.
Reaction atmosphere pressure: 7-30 kPa,
Time: 25-100 minutes
In the condition of
Composition formula: TiO _Y ,
The Ti oxide layer satisfying the Y value of 1.2 to 1.9 in terms of atomic ratio to Ti as measured by an Auger spectrometer is formed with an average layer thickness of 0.1 to 2 μm. In this state, the heat transformation treatment, preferably in the Ar atmosphere at a pressure of 7 to 50 kPa, is performed at a temperature of 1000 to 1200 ° C. for 10 to 120 minutes. crystal structure (Al, B) ₂ O ₃ layer of α-type crystal structure (Al, B) if is transformed to ₂ O ₃ layer was formed on the transformation before (Al, B) ₂ O ₃ layer surface By the action of the Ti oxide layer, the transformation from the κ-type or θ-type crystal structure to the α-type crystal structure occurs simultaneously, and cracks generated during the transformation are formed simultaneously. Therefore, the transformation crack is very finely and uniformly distributed. With the state, the since the progress of the heating transformation is accelerated considerably, crystal grain growth is remarkably inhibited, as a result formed heated transformed α-type (Al, B) ₂ O ₃ layer, transformation occurs Since the crack has a fine and uniform structure throughout the layer and becomes extremely strong against mechanical thermal shock, the upper layer of the hard coating layer is formed by the above-mentioned heat transformation α-type (Al, B) A coated cermet tool in which the ₂ O ₃ layer and the lower layer are composed of the Ti compound layer (this Ti compound layer does not undergo any change in the heat transformation treatment under the above conditions) Even in high-speed intermittent cutting with mechanical thermal shock, due to the characteristics of the heat-transformed α-type (Al, B) ₂ O ₃ layer, combined with the coexistence of the Ti compound layer having high strength , Chipping in the hard coating layer is significantly suppressed, To show excellent wear resistance over a long period of time,

(B) About the above-mentioned conventional vapor deposition α-type (Al, B) ₂ O ₃ layer and the heat-transformed α-type (Al, B) ₂ O ₃ layer of (a),
Using a field emission scanning electron microscope, as schematically shown in FIGS. 1A and 1B, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam. Then, using an electron backscatter diffraction image apparatus, an inclination angle formed by a normal line of the (0001) plane that is a crystal plane of the crystal grain is measured with respect to a normal line of the surface polished surface, and the measurement inclination angle is measured. When a pole plot graph is formed by dividing the measured inclination angles within the range of 0 to 45 degrees into pitches of 0.25 degrees and totaling the frequencies existing in each section, the conventional The vapor deposition α-type (Al, B) ₂ O ₃ layer, as illustrated in FIG. 3, shows a gentle peak in the tilt angle section in a wide range of 26 to 36 degrees, whereas the heating transformation α type (Al, B) are ₂ O ₃ layer, as illustrated in FIG. 2, 1-11 ° range Narrow appear highest peak of the inclination angle segment within the range of the inner.
The research results shown in (a) and (b) above were obtained.

The present invention has been made based on the above research results, and on the surface of a tool base composed of a WC-based cemented carbide or TiCN-based cermet,
(A) The lower layer is composed of one or more of TiC layer, TiN layer, TiCN layer, TiCO layer, and TiCNO layer formed by chemical vapor deposition, and has a total average layer thickness of 3 to 20 μm. A Ti compound layer having
(B) the upper layer has a κ-type or θ-type crystal structure in the state of chemical vapor deposition, and
Composition _{formula: (Al 1-X B X} ) 2 O 3,
In the surface of the (Al, B) ₂ O ₃ layer, which is measured by an electron beam microanalyzer (EPMA) and the X value satisfies an atomic ratio of 0.001 to 0.01,
Composition formula: TiO _Y ,
The Ti oxide layer satisfying the Y value of 1.2 to 1.9 in terms of atomic ratio to Ti as measured by an Auger spectroscopic analyzer is chemical vapor deposited with an average layer thickness of 0.1 to 2 μm. In the formed state, a heat transformation treatment is applied to transform the crystal structure of the (Al, B) ₂ O ₃ layer having the κ-type or θ-type crystal structure into an α-type crystal structure,
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface was irradiated with an electron beam, and an electron backscatter diffraction image apparatus was used to irradiate the surface polished surface. 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 , and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set to 0. In the pole plot graph formed by dividing the pitch every 25 degrees and the frequency existing in each section, the highest peak appears in the tilt angle section within the range of 1 to 11 degrees, and 1 to 15 μm. Heat-transformed α-type (Al, B) ₂ O ₃ layer having an average layer thickness,
The hard coating layer formed by the hard coating layer configured as described above in (a) and (b) is characterized by a coated cermet tool that exhibits excellent chipping resistance.

Next, the reason why the constituent layers of the hard coating layer of the coated cermet tool of the present invention are numerically limited as described above will be described below.
(A) Average layer thickness of lower layer (Ti compound layer) The Ti compound layer itself has high strength, and the presence of the Ti compound layer makes the hard coating layer have high strength, and the tool base and upper layer. The heat-transformed α-type (Al, B) ₂ O ₃ layer is firmly adhered to each other, and thus has an effect of improving the adhesion of the hard coating layer to the tool substrate, but the total average layer thickness is 3 μm. If the total thickness is less than 20 μm, thermoplastic deformation tends to occur particularly during high-speed intermittent cutting with high heat generation. Since it becomes a cause, the total average layer thickness was determined as 3-20 micrometers.

(B) Composition (Y value) and average layer thickness of Ti oxide layer As described above, the Ti oxide layer is a vaporized κ-type or θ-type (Al, B) ₂ O ₃ layer heat-transformed α-type (Al, B). ) Heat transformation to the ₂ O ₃ layer is started all over simultaneously, and the cracks generated during the heat transformation are refined and homogenized. In addition, the heat transformation is promoted, and the crystal growth is achieved by shortening the processing time. Therefore, in the above-mentioned pole plot graph, a heating transformation α-type (Al, B) ₂ O ₃ layer in which the highest peak appears in the range of measured inclination angle: 1 to 11 degrees is formed. However, even if the Y value is less than 1.2 in terms of atomic ratio with respect to Ti, more than 1.9, and even if the average layer thickness is less than 0.1 μm, the above-described effect can be sufficiently exerted. As a result, in the pole plot graph, the measured inclination angle: 1 to 11 Heating transformation α type the highest peak appears in the range of (Al, B) formed of ₂ O ₃ layer is to be a difficult, whereas the effect is sufficient with an average layer thickness of 2 [mu] m, more in thickness Is unnecessary, the Y value was determined to be 1.2 to 1.9 in terms of atomic ratio to Ti, and the average layer thickness was determined to be 0.1 to 2 μm.

(C) B content ratio and average layer thickness of upper layer [heat-transformed α-type (Al, B) ₂ O ₃ layer] The heat-transformed α-type (Al, B) ₂ O ₃ layer is composed of the constituent Al. It has excellent high temperature hardness and heat resistance due to its action, and the effect of B is further improved in high temperature hardness, but the proportion of B (X value) is the proportion of the total amount with Al, If the ratio (hereinafter the same) is less than 0.001, the desired high-temperature hardness improvement effect cannot be exhibited. On the other hand, if the ratio of B exceeds 0.01, the hexagonal crystal lattice is disturbed, and the heat transformation Since it becomes difficult to satisfactorily transform the κ-type or θ-type crystal structure into the α-type crystal structure in the treatment, the B content ratio (X value) was determined to be 0.001 to 0.01.
If the average thickness of the heat-transformed α-type (Al, B) ₂ O ₃ layer is less than 1 μm, the hard coating layer cannot be provided with sufficient high-temperature hardness and heat resistance, while the average layer thickness is 15 μm. If the thickness is too thick, chipping is likely to occur. Therefore, the average layer thickness is set to 1 to 15 μm.

  In addition, for the purpose of identification before and after the use of the cutting tool, a TiN layer having a golden color tone may be vapor-deposited as necessary, but the average layer thickness in this case may be 0.1 to 1 μm, This is because 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 with an average layer thickness of up to 1 μm.

The coated cermet tool of the present invention has an excellent heat-transformed α-type (Al, B) ₂ O ₃ layer that constitutes the upper layer of the hard coating layer even in high-speed intermittent cutting such as steel and cast iron with extremely high mechanical and thermal shock. Since it exhibits high temperature hardness and heat resistance, and excellent chipping resistance, the hard coating layer exhibits excellent wear resistance without occurrence of chipping.

  Next, the coated cermet 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 1 to 3 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 performing the processing, tool bases A to F made of a WC-base cemented carbide having a throwaway tip shape specified in ISO · CNMG120408 were manufactured.

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 f made of TiCN-based cermet having a standard / CNMG12041 chip shape were formed.

Next, an ordinary chemical vapor deposition apparatus is used on the surfaces of the tool bases A to F and the tool bases a to f, and Table 3 (l-TiCN in Table 3 is described in JP-A-6-8010). Ti compound as a lower layer of the hard coating layer under the conditions shown in (1) shows the conditions for forming a TiCN layer having a vertically grown crystal structure, and (2) shows conditions for forming a normal granular crystal structure. The layers are formed by vapor deposition in the combinations shown in Table 5 and with the target layer thickness. Then, under the conditions shown in Table 3, a (Al, B) ₂ O ₃ layer having a crystal structure of κ type or θ type is formed. Similarly, the deposition shown in Table 5 is carried out with the target layer thickness, and the Ti oxide layer is also shown in Table 4 on the surface of the κ-type or θ-type (Al, B) ₂ O ₃ layer. In a state where the vapor deposition was formed in the combination shown in Table 5 In an Ar atmosphere at 30 kPa, temperature: 1100 ° C. and subjected to heat transformation treatment at a predetermined time holding conditions in the range of 20 to 100 minutes, the κ-type or θ-type crystal structure (Al, B) ₂ O _The present invention is formed by forming a heat-transformed α-type (Al, B) ₂ O ₃ layer as an upper layer of the hard coating layer by transforming _three layers into an (Al, B) ₂ O ₃ layer having an α-type crystal structure. Cermet tools 1 to 13 were produced, respectively.

When manufacturing the cermet tools 1 to 13 according to the present invention, a test piece is prepared separately, and the test piece is loaded into the chemical vapor deposition apparatus, and a Ti oxide layer is formed on the surface of the test piece. At this point, the composition (X value and Y value) and layer thickness of the κ-type or θ-type (Al, B) ₂ O ₃ layer and the Ti oxide layer and the layer thickness were measured by an electron beam microanalyzer (EPMA), Measurement (longitudinal section measurement) was performed using an Auger spectroscopic analyzer and a scanning electron microscope. As a result, all showed the composition and average layer thickness (average value of 5-point measurement) substantially the same as the target composition and target layer thickness.

For comparison purposes, as shown in Table 6, the vapor deposition α-type (Al, B) ₂ O having the target layer thickness also shown in Table 6 under the conditions shown in Table 3 as the upper layer of the hard coating layer. Conventionally coated cermet tools 1 to 13 were manufactured under the same conditions except that _three layers were formed and the above-described Ti oxide layer was not formed and the heat transformation treatment was performed under the above conditions.

Next, an electric field is applied to the heat-transformed α-type (Al, B) ₂ O ₃ layer and vapor-deposited α-type (Al, B) ₂ O ₃ layer constituting the hard coating layer of the above-described coated cermet tool of the present invention and the conventional coated cermet tool. Pole plot graphs were prepared using an emission scanning electron microscope.
That is, the pole plot graph shows a field emission scan in a state where the surfaces of the above-mentioned heat-transformed α-type (Al, B) ₂ O ₃ layer and vapor-deposited α-type (Al, B) ₂ O ₃ layer are polished surfaces. A hexagonal crystal lattice present in the measurement range of the surface polished surface is set in a lens barrel of an electron microscope and an electron beam with an acceleration voltage of 15 kV is applied to the polished surface at an incident angle of 70 degrees with an irradiation current of 1 nA. Irradiate each of the crystal grains, and use an electron backscatter diffraction image apparatus, and a 30 × 50 μm region at an interval of 0.1 μm / step with respect to the normal of the polished surface The inclination angle formed by the normal line of the (0001) plane is measured, and among the measurement inclination angles, the measurement inclination angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. Created by counting the frequencies that exist in the.
In the pole plot graphs of the various heat-transformed α-type (Al, B) ₂ O ₃ layers and vapor-deposited α-type (Al, B) ₂ O ₃ layers obtained as a result, the inclination angle at which the (0001) plane shows the highest peak The categories are shown in Tables 5 and 6, respectively.
2 is a pole plot graph of the heat-transformed α-type (Al, B) ₂ O ₃ layer of the coated cermet tool 2 of the present invention, and FIG. 3 is a vapor-deposited α-type (Al, B) ₂ of the conventional coated cermet tool _2. Pole plot graphs of the O ₃ layer are shown respectively.

Further, for the above-described coated cermet tools 1 to 13 and the conventional coated cermet tools 1 to 13, the constituent layers of the hard coating layer were observed using an electron beam microanalyzer (EPMA) and an Auger spectroscopic analysis device (layer When the longitudinal section was observed), the former consisted of a Ti compound layer having substantially the same composition as the target composition and a heat-transformed α-type (Al, B) ₂ O ₃ layer, and the surface portion was subjected to heat transformation treatment. The presence of a Ti oxide layer formed by evaporation was also confirmed. On the other hand, it was confirmed that both of the latter consisted of a Ti compound having substantially the same composition as the target composition and a deposited α-type (Al, B) ₂ O ₃ layer. Moreover, when the thickness of the constituent layer of the hard coating layer of these coated cermet tools was measured using a scanning electron microscope (same longitudinal section measurement), the average layer thickness (substantially the same as the target layer thickness) Average value of 5-point measurement) was shown.

Next, in the state where each of the various coated cermet tools is screwed to the tip of the tool steel tool with a fixing jig, the present coated cermet tools 1 to 13 and the conventional coated cermet tools 1 to 13 are as follows.
Work material: JIS · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 350 m / min,
Incision: 1.5mm,
Feed: 0.2mm / rev,
Cutting time: 10 minutes,
Dry high-speed intermittent cutting test (normal cutting speed is 250 m / min) of alloy steel under the above conditions (referred to as cutting condition A),
Work material: JIS-S35C lengthwise equal length 4 round fluted round bars,
Cutting speed: 450 m / min,
Cutting depth: 2mm,
Feed: 0.3mm / rev,
Cutting time: 10 minutes,
Dry high-speed intermittent cutting test of carbon steel under the conditions (referred to as cutting condition B) (normal cutting speed is 300 m / min),
Work material: JIS / FC300 lengthwise equidistant 4 bars with vertical grooves,
Cutting speed: 400 m / min,
Incision: 2.5mm,
Feed: 0.25mm / rev,
Cutting time: 10 minutes,
The dry high speed intermittent cutting test (normal cutting speed is 300 m / min) of cast iron under the above conditions (referred to as cutting condition C), and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 7.

表５〜７に示される結果から、本発明被覆サーメット工具１〜１３は、いずれも加熱変態α型（Ａｌ，Ｂ）₂ Ｏ₃ 層の（０００１）面がポールプロットグラフで１〜１１度の範囲内の傾斜角区分で最高ピークを示し、機械的熱的衝撃がきわめて高く、かつ高い発熱を伴なう鋼や鋳鉄の高速断続切削でも、硬質被覆層の上部層を構成する加熱変態α型（Ａｌ，Ｂ）₂ Ｏ₃ 層がすぐれた耐チッピング性を発揮することから、切刃部のチッピング発生が著しく抑制され、すぐれた耐摩耗性を示すのに対して、硬質被覆層の上部層が、前記ポールプロットグラフでは２６〜３６度の範囲内の傾斜角区分で最高ピークを示す蒸着α型Ａｌ₂Ｏ₃層からなる従来被覆サーメット工具１〜１３においては、高速断続切削では前記蒸着α型（Ａｌ，Ｂ）₂ Ｏ₃ 層が高温強度不足のために激しい機械的熱的衝撃に耐えられず、切刃部にチッピングが発生し、比較的短時間で使用寿命に至ることが明らかである。

From the results shown in Tables 5 to 7, all of the coated cermet tools 1 to 13 of the present invention have a (0001) plane of the heat-transformed α-type (Al, B) ₂ O ₃ layer in a pole plot graph of 1 to 11 degrees. Heat transformation α-type, which forms the top layer of the hard coating layer even in high-speed intermittent cutting of steel and cast iron, which shows the highest peak in the tilt angle section within the range, has extremely high mechanical thermal shock, and generates high heat generation Since the (Al, B) ₂ O ₃ layer exhibits excellent chipping resistance, the occurrence of chipping at the cutting edge is remarkably suppressed, and excellent wear resistance is exhibited, whereas the upper layer of the hard coating layer However, in the above-described pole plot graph, in the conventional coated cermet tools 1 to 13 composed of the vapor-deposited α-type Al ₂ O ₃ layer showing the highest peak in the inclination angle range of 26 to 36 degrees, the vapor-deposited α is used in high-speed intermittent cutting. High mold (Al, B) ₂ O ₃ layer It is apparent that due to insufficient temperature strength, it cannot withstand severe mechanical thermal shock, chipping occurs at the cutting edge, and the service life is reached in a relatively short time.

  As described above, the coated cermet tool according to the present invention has excellent chipping resistance not only in continuous cutting and interrupted cutting under normal conditions such as various steels and cast iron, but also in high-speed interrupted cutting which is particularly severe cutting conditions. Since it exhibits excellent cutting performance over a long period of time, it can sufficiently satisfy the high performance of the cutting device, the labor saving and energy saving of the cutting work, and the cost reduction.

Various heating transformation α type constituting the hard layer (Al, B) ₂ O ₃ layer and deposition α-type (Al, B) schematically showing the measuring range of inclination angles of crystal grains of the (0001) plane in ₂ O ₃ layer FIG. 4 is a pole plot graph of the (0001) plane of the heat-transformed α-type (Al, B) ₂ O ₃ layer constituting the hard coating layer of the coated cermet tool 2 of the present invention. It is a pole plot graph of the (0001) plane of the vapor-deposited α-type (Al, B) ₂ O ₃ layer constituting the hard coating layer of the conventional coated cermet tool 2.

Claims (1)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) As a lower layer, each consists of one or two or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer formed by chemical vapor deposition, And a Ti compound layer having a total average layer thickness of 3 to 20 μm,
(B) the upper layer has a κ-type or θ-type crystal structure in the state of chemical vapor deposition, and
Composition _{formula: (Al 1-X B X} ) 2 O 3,
("B" in the above composition formula represents boron) When measured by an electron beam microanalyzer (EPMA), an Al-based oxide satisfying an X value of 0.001 to 0.01 in atomic ratio On the surface of the layer,
Composition formula: TiO _Y ,
The Ti oxide layer satisfying the Y value of 1.2 to 1.9 in terms of atomic ratio to Ti as measured by an Auger spectroscopic analyzer is chemical vapor deposited with an average layer thickness of 0.1 to 2 μm. In the formed state, a heat transformation treatment is performed to transform the crystal structure of the Al-based oxide layer having the κ-type or θ-type crystal structure into an α-type crystal structure,
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface was irradiated with an electron beam, and an electron backscatter diffraction image apparatus was used to irradiate the surface polished surface. 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 , and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set to 0. In the pole plot graph formed by dividing the pitch every 25 degrees and the frequency existing in each section, the highest peak appears in the tilt angle section within the range of 1 to 11 degrees, and 1 to 15 μm. Heat-transformed α-type Al-based oxide layer having an average layer thickness,
A surface-coated cermet cutting tool having excellent chipping resistance due to the hard coating layer formed by the hard coating layer constituted of (a) and (b) above.

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