JP2008055583A - Surface coated cutting tool with hard coating layer exhibiting excellent abrasion resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cutting tool with a hard coating layer exhibiting excellent abrasion resistance under high speed heavy duty cutting of a hard-to-cut material. <P>SOLUTION: This surface coated cutting tool is formed by vapor-depositing (a) a lower layer comprising Ti compound layer, and (b) an upper layer comprising modified α type Al<SB>2</SB>O<SB>3</SB>layer, when measuring an inclination angle of a normal line of a plane (0001), or a crystal plane of a crystal grain to create an inclination angle frequency-distribution graph, showing the inclination angle frequency-distribution graph which has a highest peak at an inclination angle interval in the range of 0-15° and a frequency rate in the range occupies 50% or more of the total, on the surface of a tool substrate; and a tool cutting face area alone has an outermost layer comprising a titanium oxide layer (a lower side layer) and a titanium-nitride-oxide layer (an upper side layer). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In this invention, the work material itself has a high viscosity, and the adhesiveness to the hard coating layer on the surface of the cutting tool during cutting is high, and as a result, soft steel and stainless steel that have extremely high cutting resistance, The present invention also relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) in which a hard coating layer exhibits excellent wear resistance over a long period of time in high-speed cutting of difficult-to-cut materials such as manganese steel.

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. ,
(1) The lower layer is a Ti carbide (hereinafter referred to as TiC) layer, a nitride (hereinafter also referred to as TiN) layer, a carbonitride (hereinafter referred to as TiCN) layer, a carbon oxide (hereinafter referred to as TiCO). A Ti compound layer having a total average layer thickness of 3 to 20 μm, including one or two or more of a layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(2) The upper layer has an α-type crystal structure in the state of chemical vapor deposition, and using a field emission scanning electron microscope, as shown schematically in FIG. 1, is a polished surface parallel to the tool substrate surface. Each of the crystal grains having a hexagonal crystal lattice existing within the measurement range is irradiated with an electron beam, and the normal line of the (0001) plane that is the crystal plane of the crystal grain is relative to the normal line of the polished surface. Measure the inclination angle to be made, divide the measurement inclination angle within the range of 0-45 degrees out of the measurement inclination angle for each pitch of 0.25 degree, and totalize the frequency existing in each division In the inclination angle frequency distribution graph, as illustrated in FIG. 2, the highest peak exists in the inclination angle section within the range of 0 to 15 degrees, and the total of the frequencies existing within the range of 0 to 15 degrees is as follows. , Accounting for 50% or more of the total frequency in the slope angle distribution graph It shows an inclination angle frequency distribution graph, and an aluminum oxide layer having an average layer thickness of 1.5～6Myuemu (hereinafter, referred to as modified α type the Al ₂ O ₃ layer),
A coated tool formed by vapor-depositing the hard coating layer constituted by the above (1) and (2) is known, and the coated α-type Al ₂ O ₃ layer is an α-type Al ₂ O. _{(3) In} addition to its excellent high-temperature hardness and heat resistance, it also has excellent high-temperature strength, so it has excellent resistance to high-speed cutting such as various general steels and ordinary cast iron. It is also known that it exhibits chipping and wear resistance and exhibits excellent cutting performance over a long period of time.

In general, the modified α-type Al ₂ O ₃ layer constituting the hard coating layer of the above-mentioned coated tool uses a normal chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, AlCl 3: 1~5%,} CO 2: 0.1~2%, HCl: 0.3~3%, H 2 S: 0.5~1%, Ar: 20~ 35%, H ₂ : remaining,
Reaction atmosphere temperature: 1050 to 1100 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
It is also known that vapor deposition is performed under the following conditions.
Furthermore, the Ti compound layer and the modified α-type Al ₂ O ₃ layer that also constitute the hard coating layer have a granular crystal structure, and the TiCN layer that constitutes the Ti compound layer is intended to improve the strength of the layer itself. In a normal chemical vapor deposition apparatus, a gas mixture containing organic carbonitrides is used as a reaction gas, and it is formed by chemical vapor deposition at an intermediate temperature range of 700 to 950 ° C. so that it has a vertically grown crystal structure. It is also known to do.
JP-A-2005-205586 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 tools, there is no problem when this is used for high-speed cutting of general steel such as low alloy steel and carbon steel, and ordinary cast iron such as gray cast iron, but this is especially suitable for mild steel, stainless steel, and high manganese. When used for high-speed cutting of difficult-to-cut materials such as steel, a very large mechanical load is applied to the cutting edge, and the difficult-to-cut material itself has a high viscosity, and the cutting during cutting is performed. The adhesiveness of the tool surface to the hard coating layer is also high. This tendency, combined with the increased heat generated during high-speed cutting, results in extremely high cutting resistance, especially on the rake face of the coated tool. Wear resistance becomes insufficient with respect to chips of work material, such that the result in a relatively short time service life because at present.

In view of the above, the present inventors focused on the coated tool in which the above-mentioned modified α-type Al ₂ O ₃ layer constitutes the upper layer of the hard coating layer, and in particular, high-speed cutting of difficult-to-cut materials. As a result of research to improve the wear resistance of the flank of the coated tool under severe cutting conditions,
(A) Ti compound layer of the conventional coated tool having a hard coating layer consisting of (lower layer) and the modified α type the Al ₂ O ₃ layer (the upper layer), the surface of the modified α type the Al ₂ O ₃ layer In the normal chemical vapor deposition equipment,
(1) First, as a lower layer, the reaction gas composition is in volume%,
TiCl ₄ : 0.2 to 10%,
CO ₂ : 0.1 to 10%,
Ar: 5 to 60%,
H ₂ : Remaining
And
Reaction atmosphere temperature: 800-1100 ° C.
Reaction atmosphere pressure: 4 to 70 kPa (30 to 525 torr),
And having an average layer thickness of 0.1 to 3 μm and a ratio of oxygen to Ti of 1.25 to 1.90 as measured by an Auger spectrometer,
Composition formula: TiO _W ,
In the case of
W: 1.25 to 1.90 in atomic ratio,
Forming a titanium oxide layer that satisfies
(2) Next, on the titanium oxide layer (lower layer), as an upper layer, normal conditions, that is, the reaction gas composition, in volume%,
TiCl ₄ : 0.2 to 10%,
N ₂ : 4-60%,
H ₂ : Remaining
And
Reaction atmosphere temperature: 800-1100 ° C.
Reaction atmosphere pressure: 4 to 90 kPa (30 to 675 torr),
When a TiN layer having an average layer thickness of 0.05 to 2 μm is formed under the conditions described above,
(3) When the TiN layer (upper layer) is formed, oxygen in the titanium oxide layer constituting the lower layer diffuses, and the upper layer (TiN layer) is constituted by a titanium oxynitride layer. In this case, the titanium oxide layer, which is the lower layer after the formation of the upper layer (the titanium oxynitride layer), is measured by an Auger spectrometer at the center in the thickness direction. 1.2 to 1.7, that is,
Composition formula: TiO _x ,
In the case of
X: 1.2 to 1.7 in atomic ratio,
Titanium oxide layer that satisfies
(4) Further, the upper layer composed of the titanium oxynitride layer is similarly measured at the center in the thickness direction with an Auger spectroscopic analyzer, and the ratio of diffused oxygen is 0.01 in terms of atomic ratio to nitrogen (N). ~ 0.4, i.e.
Composition formula: TiN _1-Y (O) _Y ,
(Where (O) represents diffused oxygen from the titanium oxide layer),
Y: 0.01 to 0.4 in atomic ratio
Titanium nitride oxide layer that satisfies

(B) Then, a coating layer (hereinafter referred to as “a”) composed of the titanium nitride oxide layer (upper layer) and the titanium oxide layer (lower layer) formed on the modified α-type Al ₂ O ₃ layer according to (a). Since the outermost layer itself has excellent heat resistance, it suppresses the occurrence of crater wear on the rake face of the coated tool, which is mainly caused by abrasion with chips in high-speed cutting of difficult-to-cut materials that generate high heat. Therefore, an outermost layer composed of the titanium nitride oxide layer (upper layer) and the titanium oxide layer (lower layer) is formed only on the modified α-type aluminum oxide layer on the rake face of the coated tool. The wear resistance of the rake face is provided, while the coated tool flank is made of the above-mentioned modified α-type Al ₂ O ₃ layer as the outermost surface layer of the hard coating layer, which is necessary for the flank. As a result, if hardness and wear resistance are secured In addition, the wear resistance of the coated tool as a whole is improved and the service life of the tool can be extended.
The research results shown in (a) and (b) have been obtained.

This invention was made based on the above research results,
“On the surface of the tool base made of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
(A) It consists of one or two or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer, and has a total average layer thickness of 3 to 20 μm. A lower layer composed of a Ti compound layer,
(B) A crystal grain having an α-type crystal structure in a chemical vapor deposited state and having a hexagonal crystal lattice existing in a measurement range of a polished surface parallel to the tool substrate surface using a field emission scanning electron microscope Individually irradiated with an electron beam, 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 polished surface. In the inclination angle number distribution graph obtained by dividing the measured inclination angle within the range of ˜45 degrees into every 0.25 degree pitch and counting the frequencies existing in each division, within the range of 0-15 degrees An inclination angle number distribution graph in which the highest peak exists in the inclination angle section and the total number of frequencies within the range of 0 to 15 degrees occupies 50% or more of the entire frequency in the inclination angle distribution graph. And has an average layer thickness of 1.5 to 5.9 μm An upper layer composed of a modified α-type aluminum oxide layer,
In the surface-coated cutting tool in which the layers (a) and (b) are formed by vapor deposition in order from the tool base side,
Only on the modified α-type aluminum oxide layer in the surface region of the tool base constituting the rake face of the surface-coated cutting tool,
(C) has an average layer thickness of 0.1 to 3 μm, and
Composition formula: TiO _x ,
The lower layer made of a titanium oxide layer satisfying 1.2 ≦ X ≦ 1.7 in terms of atomic ratio, as measured by an Auger spectroscopic analyzer at the center in the thickness direction,
(D) having an average layer thickness of 0.05-2 μm, and
Composition formula: TiN _1-Y (O) _Y ,
[Wherein (O) indicates diffuse oxygen from the titanium oxide layer], the central portion in the thickness direction is measured with an Auger spectroscopic analyzer, and the atomic ratio is 0.01 ≦ Y ≦ 0. An upper layer comprising a titanium oxynitride layer satisfying 4;
A coated tool (surface coated cutting tool), characterized in that an outermost layer comprising the above (c) and (d) is provided. "
It has the characteristics.

The reason why the lower layer, the upper layer, and the outermost layer of the hard coating layer of the coated tool of the present invention are limited as described above will be described below.
(1) Ti compound layer (lower layer)
The Ti compound layer basically exists as a lower layer of the modified α-type Al ₂ O ₃ layer, and allows the hard coating layer to have high-temperature strength by its excellent high-temperature strength. And the reinforcing α-type Al ₂ O ₃ layer firmly adhere to each other, and thus have an effect of improving the adhesion of the hard coating layer to the tool substrate. However, when the total average layer thickness is less than 3 μm, On the other hand, when the total average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation particularly in high-speed cutting with high heat generation, which causes uneven wear. The layer thickness was determined to be 3-20 μm.

(2) Modified α-type Al ₂ O ₃ layer (upper layer)
The maximum peak position of the measured inclination angle in the inclination angle number distribution graph of the modified α-type Al ₂ O ₃ layer is changed by changing the reaction atmosphere pressure in the chemical vapor deposition apparatus. When the reaction atmosphere pressure is 6 to 10 kpa, the highest peak appears in the inclination angle section in the range of 0 to 15 degrees, and the total of the frequencies existing in the range of 0 to 15 degrees is the inclination angle. An inclination angle number distribution graph occupying a ratio of 50% or more of the entire frequency in the number distribution graph is shown. Therefore, even if the reaction atmosphere pressure is out of the range, it is out of the range. However, the highest peak of the measured tilt angle does not appear within the range of 0 to 15 degrees, and in such a case, the desired excellent high-temperature strength cannot be provided.
The modified α-type Al ₂ O ₃ layer also has high-temperature strength in addition to the excellent high-temperature hardness and heat resistance of the α-type Al ₂ O ₃ itself, but the average layer thickness is 1 If the thickness is less than 5 μm, the above properties cannot be sufficiently provided in the hard coating layer, and if the average layer thickness exceeds 5.9 μm, chipping is likely to occur in high-speed cutting of difficult-to-cut materials. Therefore, the average layer thickness was determined to be 1.5 to 5.9 μm.

(3) Outermost layer As described above, the titanium oxynitride layer constituting the uppermost layer of the outermost layer provided only in the rake face region of the coated tool has an oxygen ratio of 1.25 to 1 in terms of atomic ratio to N as described above. .90 (W value) is formed by forming a titanium oxide layer and then depositing a TiN layer on the titanium oxide layer under normal conditions. Therefore, the TiN layer is formed when the TiN layer is formed. Although diffusion of oxygen from the titanium oxide layer is indispensable, if the W value of the titanium oxide layer is less than 1.25, the diffusion reaction of oxygen to the TiN layer is drastically reduced, and diffusion oxygen in the upper layer is reduced. When the W value exceeds 1.90, the ratio of diffused oxygen in the upper layer (Y value) is 0 in atomic ratio. Because it becomes more than 40, In this case, the oxygen ratio (X value) in the lower layer (titanium oxide layer) after the formation of the upper layer is 1.2 to 1 in terms of atomic ratio. .7, in other words, when the X value of the lower layer after the formation of the upper layer satisfies 1.2 to 1.7, the Y value of the upper layer is 0.01. -0.40 is satisfied.
The outermost layer formed only in the rake face region of the coated tool contributes to the suppression of crater wear caused by abrasion due to chips in high-speed cutting of difficult-to-cut materials as described above. When the X value and the Y value of the upper layer deviate from 1.2 to 1.7 and 0.01 to 0.40, respectively, the heat resistance action against chips becomes insufficient and the occurrence of crater wear is suppressed. From the viewpoint of developing a heat resistance effect on the chips by the outermost layer of the rake face region of the coated tool, the lower layer has an X value of 1.2 to 1.7, and the upper layer has a Y value. It was determined to be 0.01-0.40.
In addition, the average layer thicknesses of the upper layer and the lower layer are set to 0.05 to 2 μm and 0.1 to 3 μm, respectively, when the average layer thickness is less than 0.05 μm and less than 0.1 μm. On the other hand, if the average layer thickness exceeds 2 μm and 3 μm respectively, chipping is likely to occur in the rake face region. The average layer thickness of the lower layer was determined to be 0.05 to 2 μm and 0.1 to 3 μm, respectively.
The means for depositing and forming the outermost layer only on the rake face region of the coated tool is not particularly limited. For example, the modified α-type Al ₂ O ₃ layer entire surface of the rake face region and flank region of the coated tool It is possible to leave the outermost layer only in the rake face area by removing only the outermost layer in the flank area by blasting, polishing, etc. In doing so, it is of course possible to mask the modified α-type Al ₂ O ₃ layer in the flank area of the coated tool and perform vapor deposition in this state to deposit the outermost layer only in the rake face area. In any case, in the present invention, the means for depositing the outermost layer only on the rake face region of the coated tool is not particularly limited, and any means can be adopted.

The coated tool of the present invention is formed by depositing an outermost layer having excellent heat resistance against chips on the modified α-type Al ₂ O ₃ layer deposited on the rake face region. Cutting of difficult-to-cut materials (work materials) such as stainless steel, high-manganese steel, and mild steel, which has a large mechanical load on the cutting edge, has high chip viscosity, and is easy to weld to the tool surface. Even under high-speed cutting conditions with high heat generation, even if the work material and chips are heated to a high temperature and the viscosity and weldability increase further, the excellent high-temperature hardness and heat resistance of the hard coating layer Thus, the effect of suppressing the wear of the hard coating layer is sufficiently exhibited, and as a result, excellent wear resistance is exhibited over a long period of time.

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

As raw material powders, WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, and Co powder each having an average particle diameter of 1 to 3 μm are prepared. The raw material powder is blended in the blending composition shown in Table 1, added with wax, ball mill mixed in acetone for 24 hours, dried under reduced pressure, and press-molded into a green compact of a predetermined shape at a pressure of 98 MPa. The green compact is 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 is subjected to a honing process of R: 0.07 mm. Thus, a tool base made of a WC-based cemented carbide having a throwaway tip shape defined as CNMG12041 in the ISO standard in the form of having a tool mounting bolt through hole in the center. Each of the bodies A to F was produced.

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 with a ball mill for 24 hours, dry, and press-mold into a 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 sintering, the cutting edge portion is subjected to a honing process of R: 0.07 mm. Made of TiCN-based cermet with a throwaway tip shape that is defined as CNMN12041 in the ISO standard, with no holes attached to the tool body by clamping with clamp pieces To form a tool substrate a~f.

Then, each of these tool bases A to F and tool bases a to f 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, reaction gas composition: volume%, AlCl ₃ : 2.2%, CO ₂ : 1.5%, HCl: 2%, H ₂ S: 0.75%, Ar: 26.5%, H ₂ : Remaining
Reaction atmosphere temperature: 1070 ° C.
Reaction atmosphere pressure: a predetermined pressure within a range of 6 to 10 kPa,
The modified α-type Al ₂ O ₃ layer is also formed by vapor deposition with the target layer thickness shown in Table 6 under the same conditions as above,
(C) Further, a titanium oxide layer for forming the lower layer of the outermost layer [any of TiO _W (1) to (6)] is formed by vapor deposition with the target layer thickness shown in Table 6 under the conditions shown in Table 4. After that, an outermost titanium nitride layer for forming an upper layer (TiN layer) was formed by vapor deposition with the target layer thickness shown in Table 6 under the conditions shown in Table 3, and the composition shown in Table 5, ie, the thickness Measure the central portion in the length direction with an Auger spectroscopic analyzer, and form the outermost layer consisting of the lower and upper layers of the X and Y values shown in Table 5, respectively.
(D) Subsequently, wet coating was applied to the region other than the tool rake face to remove the outermost layer, and the inventive coated tools 1 to 13 each having the outermost layer provided only in the tool rake face area were manufactured.

For comparison purposes, as shown in Table 6, on the modified α-type Al ₂ O ₃ layer strip, which is the upper layer of the hard coating layer, under the same conditions except that the outermost layer is not vapor-deposited, Conventionally, the coated tools 1-13 were manufactured, respectively.

Next, the modified α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the present invention coated tools 1 to 13 and the conventional coated tools 1 to 13 is tilted using a field emission scanning electron microscope. Each angle distribution graph was created.
In other words, the slope angle distribution graph shows the polished surfaces of the modified α-type Al ₂ O ₃ layers of the present invention coated tools 1 to 13 and the conventional coated tools 1 to 13 that are parallel to the tool base surface, respectively. In this state, each polishing surface is set in a lens barrel of a field emission scanning electron microscope, and an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees is applied to the polishing surface with an irradiation current of 1 nA. Irradiate each crystal grain having a hexagonal crystal lattice existing in the range, and use an electron backscatter diffraction image apparatus to make a region of 30 × 50 μm normal to the polished surface at an interval of 0.1 μm / step. On the other hand, the inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is 0.25 degrees. Divided into different pitches and within each division. Created by counting the existing frequencies.

In the gradient angle distribution graphs of the various modified α-type Al ₂ O ₃ layers obtained as a result, as shown in Table 7, the modified α of the present coated tools 1 to 13 and the conventional coated tools 1 to 13 are shown. The type Al ₂ O ₃ layer showed an inclination angle number distribution graph in which the distribution of the measured inclination angle of the (0001) plane had the highest peak in the inclination angle section within the range of 0 to 15 degrees.
Table 7 shows the inclination angle numbers of all inclination angle numbers existing in the inclination angle sections within the range of 75 to 90 degrees in the inclination angle number distribution graphs of the various modified α-type Al ₂ O ₃ layers. The percentage of the entire distribution graph is shown.
FIG. 2 shows an inclination angle number distribution graph of the modified α-type Al ₂ O ₃ layer of the coated tool 4 of the present invention.

  Moreover, when the thickness of the constituent layer of the hard coating layer of the present invention coated tools 1 to 13 and the conventional coated tools 1 to 13 obtained as a result was measured using a scanning electron microscope (longitudinal section measurement), Also showed an average layer thickness (average value of five-point measurement) substantially the same as the target layer thickness.

Next, for the various coated tools of the present invention coated tools 1 to 13 and the conventional coated tools 1 to 13, all of them are clamped and clamped to the tip of the tool steel tool by a bolt or a clamp piece,
Work material: JIS / SUS430 round bar,
Cutting speed: 320 m / min. ,
Cutting depth: 2.5 mm,
Feed: 0.15 mm / rev. ,
Cutting time: Dry continuous high-speed cutting test of stainless steel under the condition of 5 minutes (referred to as cutting condition A) (normal cutting speed is 150 m / min.),
Work material: JIS / SS300 lengthwise equidistant four round grooved round bars,
Cutting speed: 370 m / min. ,
Cutting depth: 3.0 mm,
Feed: 0.2 mm / rev. ,
Cutting time: Dry intermittent high-speed cutting test (normal cutting speed is 200 m / min.) Of mild steel under the condition of 5 minutes (referred to as cutting condition B),
Work material: JIS / SMn443H round bar,
Cutting speed: 330 m / min. ,
Cutting depth: 2.5 mm,
Feed: 0.2 mm / rev. ,
Cutting time: Dry continuous high-speed cutting test of high manganese steel under a condition of 5 minutes (referred to as cutting condition C) (normal cutting speed is 200 m / min.),
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 8.

From the results shown in Tables 5 to 8, the present invention coated tools 1 to 13 have the modified α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer, having excellent high temperature hardness and high temperature strength, The rake face of the coated tools 1 to 13 of the present invention is provided with an outermost layer having excellent heat resistance, and the occurrence of rake face wear due to chips is suppressed. The conventional coated tool 1 in which the outermost layer is not formed by vapor deposition as a hard coating layer in the tool rake face region, while excellent wear resistance is exhibited over a long period even in high-speed cutting of difficult-to-cut materials to which cutting resistance is applied. It is clear that in -13, the progress of wear in high-speed cutting of difficult-to-cut materials, particularly rake face wear, cannot be suppressed, so that the service life is reached in a relatively short time.

  As described above, the coated tool of the present invention has a high mechanical load on the cutting blade as well as high-speed cutting processing of various steels and cast irons. It is used for high-speed cutting of difficult-to-cut materials such as mild steel, stainless steel, and high manganese steel, which has high adhesion to the hard coating layer on the cutting tool surface, resulting in extremely high cutting resistance. However, it exhibits excellent wear resistance without chipping, and exhibits excellent cutting performance over a long period of time. It is possible to cope with the conversion sufficiently satisfactorily.

It is a schematic explanatory drawing which shows the measurement range of the inclination angle in the case of measuring the (0001) plane of the crystal grain in the modified α-type Al ₂ O ₃ layer constituting the hard coating layer. The inclination angle frequency distribution graph showing the tilt angle sections of 0 to 45 degrees of the modified α type the Al ₂ O ₃ layer constituting the hard layer of the present invention coated tools 4.

Claims (1)

On the surface of the tool base composed of tungsten carbide base cemented carbide or titanium carbonitride base cermet,
(A) It consists of one or two or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer, and has a total average layer thickness of 3 to 20 μm. A lower layer composed of a Ti compound layer,
(B) A crystal grain having an α-type crystal structure in a chemical vapor deposited state and having a hexagonal crystal lattice existing in a measurement range of a polished surface parallel to the tool substrate surface using a field emission scanning electron microscope Individually irradiated with an electron beam, 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 polished surface. In the inclination angle number distribution graph obtained by dividing the measured inclination angle within the range of ˜45 degrees into every 0.25 degree pitch and counting the frequencies existing in each division, within the range of 0-15 degrees An inclination angle number distribution graph in which the highest peak exists in the inclination angle section and the total number of frequencies within the range of 0 to 15 degrees occupies 50% or more of the entire frequency in the inclination angle distribution graph. And has an average layer thickness of 1.5 to 5.9 μm An upper layer composed of a modified α-type aluminum oxide layer,
In the surface-coated cutting tool in which the layers (a) and (b) are formed by vapor deposition in order from the tool base side,
Only on the modified α-type aluminum oxide layer in the surface region of the tool base constituting the rake face of the surface-coated cutting tool,
(C) has an average layer thickness of 0.1 to 3 μm, and
Composition formula: TiO _x ,
The lower layer made of a titanium oxide layer satisfying 1.2 ≦ X ≦ 1.7 in terms of atomic ratio, as measured by an Auger spectroscopic analyzer at the center in the thickness direction,
(D) having an average layer thickness of 0.05-2 μm, and
Composition formula: TiN _1-Y (O) _Y ,
[Wherein (O) indicates diffuse oxygen from the titanium oxide layer], the central portion in the thickness direction is measured with an Auger spectroscopic analyzer, and the atomic ratio is 0.01 ≦ Y ≦ 0. An upper layer comprising a titanium oxynitride layer satisfying 4;
A surface-coated cutting tool comprising an outermost layer comprising the above (c) and (d).

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