JP4863070B2 - Surface-coated cutting tool with excellent chipping resistance with a hard coating layer in high-speed intermittent cutting of high-hardness steel - Google Patents

Description

  The present invention is a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent chipping resistance with a hard coating layer, especially in high-speed intermittent cutting of high-hardness steel such as hardened materials of alloy steel and bearing steel. It is about.

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) 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 of the lower layers. A Ti compound 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 an overall average layer thickness of 3 to 20 μm layer,
(B) Aluminum and chromium in which the upper layer has an average layer thickness of 1 to 15 μm, and the content ratio of chromium with respect to the total amount of aluminum and chromium is 0.01 to 0.10 (however, atomic ratio) A composite oxide layer [hereinafter referred to as (Al, Cr) ₂ O ₃ ] layer,
There is known a coated tool formed by chemical vapor deposition of the hard coating layer composed of the above (a) and (b), and this coated tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is well known that it is used.

In the above-described conventional coated tool, the constituent layer of the hard coating layer generally has a granular crystal structure, and further, for the purpose of improving the strength of the TiCN layer constituting the Ti compound layer as the lower layer, In a normal chemical vapor deposition apparatus, a vertically grown crystal structure is formed by chemical vapor deposition at a medium temperature range of 700 to 950 ° C. using a mixed gas containing an organic carbonitride such as CH ₃ CN as a reaction gas. It is also known to have it.

In addition, the (Al, Cr) ₂ O ₃ layer constituting the hard coating layer of the conventional coated tool described above,
Reaction gas composition: by _{volume%, AlCl 3: 2.3~4%,} CrCl 3: 0.04~0.26%, CO 2: 6~8%, HCl: 1.5~3%, H 2 S : 0.05~0.2%, H _2: remainder,
Reaction atmosphere temperature: 1020 to 1050 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
It is also known that vapor deposition is performed under the following conditions.
JP 52-66508 A Japanese Patent Laid-Open No. 6-8010

In recent years, the performance of cutting machines has improved dramatically, while there is a strong demand for labor saving and energy saving and further cost reduction for cutting, and along with this, the tendency to increase cutting speed for the purpose of improving cutting efficiency However, in the above-mentioned conventional coated tool, there is no problem when it is used for continuous cutting and interrupted cutting under normal conditions such as steel and cast iron, but this is especially hardened for alloy steel and bearing steel. When using high-hardness steel such as steel for high-speed interrupted cutting with severe cutting conditions, that is, for high-speed intermittent cutting where a very high mechanical load is applied to the cutting edge, the lower layer of the hard coating layer (Ti compound layer) Since the high-temperature strength is insufficient and the bonding strength between the upper layer ((Al, Cr) ₂ O ₃ layer) and the lower layer (Ti compound layer) is not sufficient, To be satisfied Scratches, since this results in a hard coating layer chipping (minute chipping) tends to occur, at present, leading to a relatively short time service life.

  In view of the above, the present inventors, from the above viewpoint, in order to improve the chipping resistance of the hard coating layer of the above-mentioned coated tool, the TiCN layer constituting the Ti compound layer, which is the lower layer thereof, that is, the Ti compound As a result of conducting research focusing on the TiCN layer having a relatively high high-temperature strength among the layers, and further researching the intermediate layer for improving the bonding strength between the upper layer and the lower layer, the following knowledge was obtained. .

<About the lower layer>
(A) First, in the hard coating layer of the conventional coated tool, the TiCN layer (hereinafter referred to as the conventional TiCN layer) of the Ti compound layers constituting the lower layer is, for example, an ordinary chemical vapor deposition apparatus.
Reaction gas composition: by _{volume%, TiCl 4: 2~10%,} CH 3 CN: 0.5~3%, N 2: 10~30%, H 2: remainder,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 6-20 kPa,
It is formed by vapor deposition under the conditions (called normal conditions)
Reaction gas composition: volume%, TiCl ₄ : 2 to 10%, CrCl ₃ : 0.01 to 0.5%, CH ₃ CN: 0.5 to 3%, N ₂ : 30 to 45%, Ar: remaining ,
Reaction atmosphere temperature: 900-1020 ° C.
Reaction atmosphere pressure: 6-20 kPa,
Compared with the above-mentioned conditions, that is, the above-mentioned normal conditions, the H ₂ gas that is the carrier gas of the reaction gas is replaced with Ar gas, the relative amount of N ₂ gas is increased, and a very small amount of CrCl ₃ gas is added. Titanium / chromium composite carbonitriding with a chromium content of 0.005 to 0.05 with respect to the total amount of titanium / chromium (provided by vapor deposition) under relatively high reaction atmosphere temperature When a product (hereinafter referred to as “(Ti, Cr) CN”) layer is formed, the resulting (Ti, Cr) CN layer has the same crystal structure as that of the above-described conventional TiCN layer, that is, Ti, Cr at lattice points. It has a NaCl-type face-centered cubic crystal structure in which constituent atoms consisting of carbon (C) and nitrogen (N) are present, respectively, but has a high-temperature strength superior to that of the conventional TiCN layer.

(B) For the conventional TiCN layer and the (Ti, Cr) CN layer of (a),
Using a field emission scanning electron microscope, as illustrated in the schematic explanatory diagrams of FIGS. 1A and 1B, the electron beam is individually applied to each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface. Is measured with respect to the normal of the surface-polished surface, and the tilt angle formed by the normal of the {112} plane that is the crystal plane of the crystal grain is measured. When the tilt angle number distribution graph is created by dividing the measured tilt angle within the range of 0.25 degrees into pitches and adding up the frequencies existing in each section, the conventional TiCN layer is 3, while the distribution of the measured tilt angle of the {112} plane shows an unbiased tilt angle number distribution graph within the range of 0 to 45 degrees, the (Ti, Cr) CN layer has As shown in Fig. 2, the sharpest peak appears at a specific position in the tilt angle section. The sharp maximum peak height and tilt angle division position appearing in the tilt angle sections of the graph the horizontal axis is the (Ti, Cr) be varied by adjusting the content ratio of Cr in the CN layer.

(C) As described above, when the (Ti, Cr) CN layer is formed, the Cr content in the layer is 0.005 to 0.05 in terms of the atomic ratio to the total amount with Ti as described above. In the tilt angle number distribution graph of the (Ti, Cr) CN layer, a sharp maximum peak appears in the range of 0 to 10 degrees of the tilt angle section and exists in the range of 0 to 10 degrees. The frequency ratio comes to show an inclination angle frequency distribution graph that occupies a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution graph. Therefore, the Cr content ratio in the (Ti, Cr) CN layer is Even if it is out of the lower range or out of the higher range, the sharpest peak in the inclination angle number distribution graph is out of the 0 to 10 degree range of the inclination angle section, and the 0 to 10 degree range. Every time it is in range The number ratio also becomes less than 45%, that this can not be improved in high-temperature strength of the single-stage case.
Further, the Cr component of the (Ti, Cr) CN layer has the effect of improving the high-temperature strength of the layer itself as compared with the conventional TiCN layer not containing the Cr component in the layer, in addition to the above-described effects. In this case, if the content ratio is less than 0.005 in terms of the atomic ratio to the total amount with Ti, the desired high-temperature strength improvement effect does not appear, while if the content ratio exceeds 0.05, the softening rapidly occurs. Further, in high-speed intermittent cutting with high heat generation, it is easy for thermoplastic deformation that causes uneven wear to occur at the cutting edge, so the content ratio is 0.005 to 0.005 in terms of atomic ratio to the total amount with Ti. Must be 05.

<About the intermediate layer>
Next, various investigations were made on the intermediate layer for improving the bonding strength between the upper layer and the lower layer. The intermediate layer was composed of a hexagonal chromium nitride (hereinafter referred to as “Cr ₂ N”) layer, and In the crystal structure analysis by X-ray, the measured diffraction intensity from the (hkil) plane (where i = − (h + k)) of hexagonal chromium nitride is I (hkil), and ICDD PDF No. 35-803 ^(Note) Relative diffraction intensity I _R (hkil) = I (hkil) / I ₀ (hkil) calculated as a ratio of standard X-ray diffraction intensity I ₀ (hkil) to I (hkil) ) For the diffractive surfaces (11-20), (0002), (11-21), (11-22), (30-30), (11-23), I _R (0002) is maximum. It was found that the Cr ₂ N layer showing the value is optimal.
(Note) “ICDD PDF” is an abbreviation of Powder Diffraction File (PDF) of International Center for Diffraction Data (ICDD).
Specifically, it is as follows.

(D) When the lower layer of the hard coating layer is composed of a (Ti, Cr) CN layer, the lower layer and the Cr ₂ N layer as the intermediate layer are both nitride-based compounds containing Cr, The interface between the layer and the intermediate layer has a sufficient chemical affinity, while the Cr ₂ N layer as the intermediate layer and the (Al, Cr) ₂ O ₃ layer as the upper layer are both hexagonal crystal structures. And the lattice constant of the a axis is almost equal, so there is no crystal lattice mismatch and the coefficient of thermal expansion is relatively close. Therefore, the interface is formed as an extremely stable interface, Excellent adhesion in

(E) Depending on the chemical vapor deposition conditions, the Cr ₂ N layer has a measured diffraction intensity from the (hkil) plane of hexagonal chromium nitride (where i = − (h + k)) in the crystal structure analysis by X-ray I ( hKil) and ICDD PDF No. Relative diffraction intensity I _R (hkil) = I (hkil) / I ₀ (hkil) calculated as a ratio of standard X-ray diffraction intensity I ₀ (hkil) to I (hkil) described in 35-803, When the diffraction planes (11-20), (0002), (11-21), (11-22), (30-30), and (11-23) are obtained, I _R (0002) shows the maximum value. It becomes like this. The standard X-ray diffraction intensity I ₀ (hkil) is shown as the diffraction intensity from the (hkil) plane of the Cr ₂ N powder particles, and the measurement sample is isotropic without being collected on a specific crystal plane. Therefore, I _R (hkil), which is the ratio of the measured X-ray diffraction intensity I (hkil) to the standard X-ray diffraction intensity I ₀ (hkil), corresponds to each (hkil) of the measurement sample. ) It is considered to indicate the degree of assembly on the surface. Therefore, the larger the value of I _R (hkil), the more the (hkil) planes are gathered in the tangential direction of the substrate. Therefore, the Cr ₂ N layer having a maximum value of I _R (0002) The plane parallel to the (0001) plane that is the bottom surface of the hexagonal crystal is most strongly assembled in the tangential direction of the substrate. When the degree of aggregation of the (0001) plane in the tangential direction of the substrate of the Cr ₂ N layer as the intermediate layer is increased, the (Al, Cr) ₂ O ₃ layer as the upper layer is
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane, is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, when an inclination angle number distribution graph is created by counting the frequencies existing in each section, the sharpest peak appears in the range of 0 to 10 degrees and exists in the range of 0 to 10 degrees. An inclination angle number distribution graph in which the frequency ratio occupies 45% or more is shown. As a result, the (Al, Cr) ₂ O ₃ layer as the upper layer has higher temperature strength.

(F) As described above, the lower layer of the hard coating layer is composed of a (Ti, Cr) CN layer, and the base layer is interposed between the upper layer composed of the (Al, Cr) ₂ O ₃ layer and the lower layer. When a hexagonal Cr ₂ N layer having a high degree of aggregation of the (0001) plane in the tangential direction is deposited as an intermediate layer, not only the upper layer but also the lower layer has excellent high-temperature strength characteristics. The hard coating layer as a whole has excellent high-temperature strength because it adheres firmly to the upper and lower layers and has high bonding strength, especially high-speed intermittent cutting of high-hardness steel with extremely high loads. Also in processing, the hard coating layer exhibits excellent chipping resistance and exhibits excellent wear resistance over a long period of time.
The research results shown in (a) to (f) above were obtained.

This invention was made based on the above research results,
“(1) On the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) The lower layer has an average layer thickness of 2.5 to 150 μm, and the chromium content (Cr / (Ti + Cr)) relative to the total amount of titanium and chromium is 0.005 to 0.05 (provided that , Atomic ratio) titanium and chromium composite carbonitride layer,
(B) The intermediate layer is made of hexagonal chromium nitride having an average layer thickness of 0.1 to 3 μm. In the crystal structure analysis by X-ray, the (hkil) plane of hexagonal chromium nitride (where i = − The measured diffraction intensity from (h + k)) is I (hkil), and ICDD
PDF No. Relative diffraction intensity I _R (hkil) = I (hkil) / I ₀ (hkil) calculated as a ratio of standard X-ray diffraction intensity I ₀ (hkil) to I (hkil) described in 35-803, When the diffraction planes (11-20), (0002), (11-21), (11-22), (30-30), and (11-23) are obtained, I _R (0002) shows the maximum value. Hexagonal chromium nitride layer,
(C) The upper layer has an average layer thickness of 1 to 15 μm, and the chromium content (Cr / (Al + Cr)) with respect to the total amount of aluminum and chromium is 0.01 to 0.10 (however, atoms Ratio) aluminum and chromium composite oxide layer,
A surface-coated cutting tool that exhibits excellent chipping resistance in high-speed intermittent cutting of high-hardness steel, which is formed by chemical vapor deposition of the hard coating layer configured as described above in (a) to (c).
(2) In the surface-coated cutting tool of (1),
The lower layer composed of the composite carbonitride layer of titanium and chromium in (a) above,
Using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal grain is normal to the surface polished surface. The tilt angle formed by the normal of the {112} plane, which is the crystal plane, is measured, and, among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. An inclination angle frequency distribution graph that occupies a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution graph,
(1) The surface-coated cutting tool according to (1).
(3) In the surface-coated cutting tool of (1),
The upper layer made of the composite oxide layer of aluminum and chromium in (c) is
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane, is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. An inclination angle frequency distribution graph that occupies a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution graph,
(1) The surface-coated cutting tool according to (1).
(4) In the surface-coated cutting tool according to (1),
The lower layer composed of the composite carbonitride layer of titanium and chromium in (a) above,
Using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal grain is normal to the surface polished surface. The tilt angle formed by the normal of the {112} plane, which is the crystal plane, is measured, and, among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. An inclination angle frequency distribution graph in which the sum of the frequencies is 45% or more of the entire frequency in the inclination angle frequency distribution graph,
The upper layer made of the composite oxide layer of aluminum and chromium in (c) is
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane, is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. An inclination angle frequency distribution graph that occupies a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution graph,
(1) The surface-coated cutting tool according to (1).
(5) In the surface-coated cutting tool according to (1) to (4),
Between the surface of the tool base and the lower layer made of the titanium and chromium composite carbonitride layer of (a), a Ti carbide layer having a total average layer thickness of 0.1 to 5 μm, and nitriding Interposing an adhesive Ti compound layer formed by chemical vapor deposition consisting of one or more of a physical layer, a carbonitride layer, a carbonate layer, and a carbonitride layer,
The surface-coated cutting tool according to any one of (1) to (4), wherein: "
It has the characteristics.

  Next, the reason why the constituent layers of the hard coating layer of the coated tool of the present invention are numerically limited as described above will be described below.

(A) Lower (Ti, Cr) CN layer (Ti, Cr) CN layer existing in a predetermined inclination angle section where the highest peak position in the inclination angle section of the inclination angle number distribution graph of the Ti layer and the highest peak exists As described above, the frequency ratio is the atomic ratio of the Cr content in the layer to the total amount with Ti, and is 0.005 to 0.05, which is the highest in the inclination angle category within the range of 0 to 10 degrees. The frequency ratio in which a peak exists and is within the range of 0 to 10 degrees can be 45% or more of the entire frequency in the inclination angle frequency distribution graph. Even if it is less than 005 or more than 0.05, the inclination angle section where the highest peak position appears is out of the range of 0 to 10 degrees, and the frequency ratio existing in the range of 0 to 10 degrees is less than 45%. And then With high-speed intermittent cutting, chipping does not occur in the hard coating layer, and an excellent effect of improving high-temperature strength cannot be ensured.
Thus, the lower (Ti, Cr) CN layer has higher temperature strength than the conventional TiCN layer, but if the average layer thickness is less than 2.5 μm, the desired excellent high temperature is obtained. The hard coating layer cannot be sufficiently provided with the effect of improving the strength. On the other hand, if the average layer thickness exceeds 15 μm, the thermoplastic deformation that causes uneven wear tends to occur, and wear is accelerated. Therefore, the average layer thickness was determined to be 2.5 to 15 μm.

(B) In Cr ₂ N layer X-ray diffraction of the intermediate layer, I _R (0002) shows a maximum value, that is, Cr having a hexagonal crystal structure with a high degree of aggregation of the (0001) plane in the tangential direction of the substrate ₂ N layer is formed on the lower layer ((Ti, Cr) CN layer) by, for example, a normal chemical vapor deposition apparatus.
Reaction gas composition: volume%, CrCl ₃ : 0.1 to 5%, N ₂ : 20 to 70%, HCl: 0.3 to ₂ %, H ₂ : remaining reaction atmosphere temperature: 900 to 1040 ° C,
Reaction atmosphere pressure: 6-20 kPa,
It is formed by vapor deposition under the conditions of
When the vapor deposition conditions are out of the above range, the degree of assembly of the (0001) plane in the tangential direction of the base of the Cr ₂ N layer to be formed decreases, and as a result, vapor deposition is formed on the Cr ₂ N layer. The frequency ratio of the (0001) plane of the upper layer ((Al, Cr) ₂ O ₃ layer) is also reduced, and the effect of improving the high temperature strength of the upper layer is also reduced.
Further, if the average layer thickness of the Cr ₂ N layer as an intermediate layer is less than 0.1 μm, improvement in adhesion between the lower layer and the upper layer and improvement in bonding strength cannot be expected, while the average layer thickness is 3 μm. If it exceeds 1, the high temperature hardness of the hard coating layer will be lowered, so the average layer thickness was determined to be 0.1 to 3 μm.

(C) (Al, Cr) ₂ O ₃ layer of upper layer The content ratio of Cr to the total amount of Al and Cr (Cr / (Al + Cr)) is 0.01 to 0.10 (however, atomic ratio) ( The Al, Cr) ₂ O ₃ layer is formed on the intermediate layer composed of the Cr ₂ N layer, for example, by a normal vapor deposition device.
Reaction gas composition: by _{volume%, AlCl 3: 2.3~4%,} CrCl 3: 0.04~0.26%, CO 2: 6~8%, HCl: 1.5~3%, H 2 S : 0.05~0.2%, H _2: remainder,
Reaction atmosphere temperature: 1020 to 1050 ° C.
Reaction atmosphere pressure: 6 to 10 kPa,
It is formed by vapor deposition under the conditions described above and has excellent high-temperature hardness and heat resistance, which not only contributes to improving the wear resistance of the hard coating layer, but also has excellent high-temperature strength and contributes to improved chipping resistance. To do.
That is, for the (Al, Cr) ₂ O ₃ layer formed by vapor deposition under the above conditions,
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane, is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. The inclination frequency distribution graph occupies a ratio of 45% or more of the entire frequency in the inclination angle distribution graph. Therefore, when the Cr content in the layer is out of the above range, the inclination angle 0 to 10 degrees in the number distribution graph Ratio of the tilt angle number in the range becomes less than 45%, it can not be obtained the desired high-temperature strength enhancing effect.
Further, if the average layer thickness of the (Al, Cr) ₂ O ₃ layer is less than 1 μm, the hard coating layer cannot exhibit sufficient wear resistance, while the average layer thickness exceeds 15 μm. If it becomes too much, chipping is likely to occur, so the average layer thickness was determined to be 1 to 15 μm.

(D) Adhesive Ti compound layer To further improve the adhesion between the tool substrate surface and the lower layer of the hard coating layer ((Ti, Cr) CN layer), a total average layer thickness of 0.1 to 5 μm And an adhesive Ti compound layer formed by chemical vapor deposition comprising one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer. Can intervene. The adhesion Ti compound layer is firmly adhered to both the tool substrate and the (Ti, Cr) CN layer as the lower layer, and thus has an effect of improving the adhesion of the hard coating layer to the tool substrate. If the total average layer thickness is less than 0.1 μm, the desired adhesion cannot be ensured. On the other hand, the total average layer thickness up to 5 μm is sufficient. It was determined to be 1 to 5 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 the outermost layer, if necessary, but from the viewpoint of the identification effect, the average layer A thickness of 0.1 to 1 μm is sufficient.

The coated tool of the present invention is a lower layer of the hard coating layer even in high-speed intermittent cutting of high-hardness steel such as hardened steel of alloy steel, bearing steel, and the like, which places a large load on the cutting edge ( The Ti, Cr) CN layer has excellent high-temperature strength, and the upper layer (Al, Cr) ₂ O ₃ layer has excellent high-temperature strength with excellent high-temperature hardness. The layer is firmly bonded via the Cr ₂ N layer, which is an intermediate layer, so that the entire hard coating layer has excellent chipping resistance and wear resistance, and has an excellent tool over a long period of time. It demonstrates its characteristics.

  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 1 to 3 μm are prepared as raw material powders. These raw material powders are blended in the blending composition shown in Table 1, added with wax, ball milled in acetone for 20 hours, dried under reduced pressure, and pressed into a compact of a predetermined shape at a pressure of 98 MPa. The green compact was vacuum-sintered at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa, and after sintering, the cutting edge portion was R: 0.05 mm honing By performing the processing, tool bases A to F made of a WC-base cemented carbide having a throwaway tip shape defined in ISO · CNMG12041 were manufactured.

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 them for 20 hours with a ball mill, dry them, and press-mold them into green compacts at a pressure of 98 MPa. 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. Tool bases a to f made of TiCN-based cermet having a chip shape conforming to ISO standards / CNMG 120212 were formed.

Next, on the surfaces of the tool bases A to F and the tool bases a to f, using a normal chemical vapor deposition apparatus, a (Ti, Cr) CN layer as a lower layer of the hard coating layer is subjected to the conditions shown in Table 3. Then, vapor deposition is performed with the target layer thickness shown in Table 7, and then, under the conditions shown in Table 4, a Cr ₂ N layer as an intermediate layer is vapor-deposited with the target layer thickness shown in Table 7, By coating the (Al, Cr) ₂ O ₃ layer as an upper layer with the target layer thickness shown in Table 7 under the conditions shown in Table 5, the coated tools 1 to 13 of the present invention were manufactured. .
Of the above-mentioned coated tools of the present invention, the coated tools 2-7 and 9-13 of the present invention are first adhered under the conditions shown in Table 6 so that the total target layer thickness shown in Table 7 is obtained. After chemical vapor deposition of the compound layer, a lower layer ((Ti, Cr) CN layer) was formed on the adhesive Ti compound layer by chemical vapor deposition.

For comparison purposes, a conventional TiCN layer is deposited as a lower layer of the hard coating layer by vapor deposition with a target layer thickness shown in Table 8 under the conditions shown in Table 3, and (Al, Conventionally coated tools 1 to 13 were respectively manufactured by vapor-depositing Cr) ₂ O ₃ layers under the conditions shown in Table 5 and with the target layer thicknesses also shown in Table 8.
(The hard coating layer differs between the present coated tool and the conventional coated tool depending on the type of the lower layer and the presence or absence of the Cr ₂ N layer as the intermediate layer.)

Next, the measured X-ray diffraction intensity of the Cr ₂ N layer was determined by the 2θ-θ method using a normal powder X-ray diffractometer for the hard coating layer of the coated tool of the present invention. A Cu Kα1 line was used as the X-ray source, and the diffraction peak from the Kα2 line was removed by analysis software attached to the apparatus. In addition, when providing a TiN layer in a part of hard coating layer of this invention, ₂ (theta) value (42.61 degree) of (11-21) surface of Cr2N and 2 (theta) value (42.61) of (200) surface of TiN. 60 degrees), the X-ray diffraction peaks of the two cannot be separated. In this case, the diffraction intensity of the (200) plane of TiN is obtained by calculation using the intensity ratio in the standard X-ray diffraction intensity with the diffraction intensity of the (111) plane, and this value is measured near 42.6 degrees. By subtracting from the intensity, the measured X-ray diffraction intensity of the (11-21) plane of the Cr ₂ N layer was determined. The standard X-ray diffraction intensity of TiN is ICDD PDF No. The value described in 38-1420 was adopted.
TiN I (200) = I (111) × I ₀ (200) / I ₀ (111)
= I (111) × 100/72
Cr ₂ N I (11-21) = I [42.6 °] −TiN I (111) × 100/72

Next, with respect to the (Ti, Cr) CN layer and the conventional TiCN layer constituting the lower layer of the hard coating layer of the present invention-coated tool and the conventional coated tool, a gradient angle distribution graph is used using a field emission scanning electron microscope. Was created respectively.
That is, the tilt angle number distribution graph is set in a lens barrel of a field emission scanning electron microscope with the surfaces of the modified TiCN layer and the conventional TiCN layer being polished surfaces, and 70 ° on the polished surface. An electron backscatter diffraction imaging apparatus is irradiated by irradiating an electron beam with an acceleration voltage of 15 kV at an incident angle of 1 nA with an irradiation current of 1 nA on each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface. Using a 30 × 50 μm region at an interval of 0.1 μm / step, the inclination angle formed by the normal of the {112} plane, which is the crystal plane of the crystal grain, is measured with respect to the normal of the polished surface. Based on this measurement result, among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are divided for each pitch of 0.25 degrees, and the frequencies existing in each section are tabulated. Created by.

    In the inclination angle number distribution graphs of various (Ti, Cr) CN layers and conventional TiCN layers obtained as a result, the inclination angle section where the {112} plane shows the highest peak, and the inclination angle within the range of 0 to 10 degrees. Tables 7 and 8 show the ratios of the number of inclination angles existing in the section to the number of inclination angles in the entire inclination angle distribution graph.

In the above-mentioned various inclination angle number distribution graphs, as shown in Table 7, each of the (Ti, Cr) CN layers of the inventive coated tools 1 to 13 has a distribution of measured inclination angles on the {112} plane of 0 to 0. An inclination angle number distribution graph in which the highest peak appears in the inclination angle section within the range of 10 degrees and the ratio of the inclination angle numbers existing in the inclination angle section within the range of 0 to 10 degrees is 45% or more is shown. On the other hand, as shown in Table 8, the conventional TiCN layers of the conventional coated tools 1 to 13 are all unbiased with the distribution of measured inclination angles on the {112} plane being in the range of 0 to 45 degrees, and the highest peak. The inclination angle number distribution graph in which the ratio of the inclination angle number existing in the inclination angle section within the range of 0 to 10 degrees is 30% or less is also present.
FIG. 2 shows an inclination angle number distribution graph of the (Ti, Cr) CN layer of the coated tool 6 of the present invention, and FIG. 3 shows an inclination angle number distribution graph of the conventional TiCN layer of the conventional coated tool 6. .

In the same manner as described above, the field emission scanning electron microscope is used for the (Al, Cr) ₂ O ₃ layer constituting the upper layer of the hard coating layer of the present coated tools 1 to 13 and the conventional coated tools 1 to 13. Thus, an inclination angle number distribution graph was created.
As shown in Table 7, with respect to all the (Al, Cr) ₂ O ₃ layers of the coated tools 1 to 13 of the present invention, the inclination angle distribution in which the distribution of the measured inclination angle on the (0001) plane is in the range of 0 to 10 degrees. Table 8 shows a slope angle distribution graph in which the highest peak appears and the ratio of the slope angle number existing in the slope angle range within the range of 0 to 10 degrees is 45% or more. As described above, for the (Al, Cr) ₂ O ₃ layer of the conventional coated tools 1 to 13, the peak of the measured inclination angle distribution of the (0001) plane always appears in the inclination angle section within the range of 0 to 10 degrees. In addition, since the ratio of the number of inclination angles existing in the inclination angle section within the range of 0 to 10 degrees is not always 45% or more, the conventional coated tools 1 to 13 have excellent high temperatures. (Al, _Cr) of the intensity 2 _{O 3} layer is stably formed It not is. From this, the (Al, Cr) ₂ O ₃ layer was formed by vapor deposition with the inventive coated tools 1 to 13 through an intermediate layer composed of a hexagonal structure Cr ₂ N layer having a high degree of (0001) plane orientation. It can be seen that the frequency ratio of 0 to 10 degrees on the (0001) plane of the (Al, Cr) ₂ O ₃ layer was increased.
5 is an inclination angle distribution graph of the (Al, Cr) ₂ O ₃ layer of the present coated tool 6, and FIG. 6 is an inclination angle distribution graph of the (Al, Cr) ₂ O ₃ layer of the conventional coated tool 6. Respectively.

  Further, with respect to the above-mentioned coated tools 1 to 13 of the present invention and the conventional coated tools 1 to 13, each constituent layer of the hard coating layer is observed using an electron beam microanalyzer (EPMA) and an Auger spectroscopic analyzer (longitudinal layer cutting). When the surface was observed), it was confirmed that the former and the latter consisted of layers having substantially the same composition as the target composition. Moreover, when the thickness of the constituent layer of the hard coating layer of these coated tools was measured using a scanning electron microscope (similarly longitudinal section measurement), the average layer thickness (5 The average value of point measurement) was shown.

Next, in the state where all of the above various coated tools are screwed to the tip of the tool steel tool with a fixing jig, the present coated tools 1 to 13 and the conventional coated tools 1 to 13,
Work material: JIS / SKD5 quenching material (HRC51), 4 longitudinally spaced round bars with equal intervals in the length direction,
Cutting speed: 300 m / min,
Cutting depth: 0.8 mm,
Feed: 0.20 mm / rev,
Cutting time: 10 minutes,
Wet intermittent high-speed cutting test (normal cutting speed is 140 m / min) of alloy tool steel under the above conditions (referred to as cutting condition A),
Work material: JIS · SKT6 quenching material (HRC54) in the longitudinal direction of four equally spaced round bars,
Cutting speed: 250 m / min,
Cutting depth: 1.2 mm,
Feed: 0.25 mm / rev,
Cutting time: 10 minutes,
Wet intermittent high-speed cutting test (normal cutting speed is 100 m / min) of alloy tool steel under the conditions (referred to as cutting conditions B),
Work material: JIS / SUJ2 quenching material (HRC52) in the longitudinal direction with four equally spaced round bars,
Cutting speed: 260 m / min,
Cutting depth: 0.9 mm,
Feed: 0.18 mm / rev,
Cutting time: 10 minutes,
Wet intermittent high-speed cutting test of bearing steel under the above conditions (referred to as cutting condition C) (normal cutting speed is 130 m / min),
The flank wear width of the cutting edge was measured in any cutting test (using water-soluble cutting oil). The measurement results are shown in Table 9.

From the results shown in Tables 7 to 9, in the coated tools 1 to 13 of the present invention, the lower layer of the hard coating layer ((Ti, Cr) CN layer) has an inclination angle of {112} plane of 0 to 10 for all. An inclination angle number distribution graph showing the highest peak in the inclination angle section within the range of degrees and a frequency ratio in the range of 0 to 10 degrees occupying 45% or more is shown, and the tangential direction of the substrate as the intermediate layer The upper layer ((Al, Cr) ₂ O ₃ layer) of the hard coating layer is interposed by interposing a Cr ₂ N layer having a hexagonal crystal structure with a high degree of aggregation of the (0001) plane of (0001) As shown in the inclination angle number distribution graph, the inclination angle of the surface shows the highest peak in the inclination angle section in the range of 0 to 10 degrees, and the total frequency in the range of 0 to 10 degrees occupies 45% or more. As a result, a large load is applied to the cutting edge. That, for example, alloy steel, even at high intermittent cutting machining hardened steel such as hardened material bearing steel having the (Ti, Cr) high-temperature strength of CN layer is more excellent, also the Cr ₂ N The layer has excellent adhesion and bonding strength, and further, the (Al, Cr) ₂ O ₃ layer has excellent high temperature hardness and high temperature strength, so that the occurrence of chipping is remarkably suppressed as the entire hard coating layer, Excellent wear resistance.
However, the lower layer of the hard coating layer is composed of a conventional TiCN layer showing an inclination angle distribution graph in which the distribution of measured inclination angles on the {112} plane is unbiased within the range of 0 to 45 degrees and there is no highest peak. In the conventional coated tools 1 to 13, the high-speed intermittent cutting of high-hardness steel causes chipping and chipping in the hard coating layer due to insufficient high-temperature strength of the hard coating layer, resulting in a service life in a relatively short time. It is clear.

  As described above, the coated tool of the present invention is not limited to continuous cutting and interrupted cutting under normal conditions such as various steels and cast iron, for example, high-hardness steel such as alloy steel, hardened material of bearing steel, etc. The hard coating layer exhibits excellent chipping resistance even during high-speed intermittent cutting that requires particularly high high-temperature strength, and exhibits excellent cutting performance over a long period of time. It can fully satisfy the labor-saving and energy-saving of cutting and cost reduction.

It is a schematic explanatory drawing which shows the measurement range of the inclination angle of the {112} plane of the crystal grain in the (Ti, Cr) CN layer and the conventional TiCN layer which comprise the lower layer of a hard coating layer. It is an inclination angle number distribution graph of the {112} plane of the (Ti, Cr) CN layer constituting the lower layer of the hard coating layer of the coated tool 6 of the present invention. It is a gradient angle number distribution graph of the {112} plane of the conventional TiCN layer which comprises the lower layer of the hard coating layer of the conventional coating tool 6. FIG. It is a schematic diagram illustrating a measurement range of the hard coating layer constituting the upper layer of the (Al, Cr) crystal grains (0001) in ₂ O ₃ layer plane inclination angle. It is an inclination angle number distribution graph of the (0001) plane of the (Al, Cr) ₂ O ₃ layer constituting the upper layer of the hard coating layer of the coated tool 6 of the present invention. It is an inclination angle number distribution graph of the (0001) plane of the (Al, Cr) ₂ O ₃ layer constituting the upper layer of the hard coating layer of the conventional coated tool 6.

Claims (5)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) The lower layer has an average layer thickness of 2.5 to 15 μm, and the chromium content (Cr / (Ti + Cr)) relative to the total amount of titanium and chromium is 0.005 to 0.05 (however, , Atomic ratio) titanium and chromium composite carbonitride layer,
(B) The intermediate layer is made of hexagonal chromium nitride having an average layer thickness of 0.1 to 3 μm. In the crystal structure analysis by X-ray, the (hkil) plane of hexagonal chromium nitride (where i = − (H + k)) is defined as I (hkil), and ICDD PDF No. Relative diffraction intensity I _R (hkil) = I (hkil) / I ₀ (hkil) calculated as a ratio of standard X-ray diffraction intensity I ₀ (hkil) to I (hkil) described in 35-803, When the diffraction planes (11-20), (0002), (11-21), (11-22), (30-30), and (11-23) are obtained, I _R (0002) shows the maximum value. Hexagonal chromium nitride layer,
(C) The upper layer has an average layer thickness of 1 to 15 μm, and the chromium content (Cr / (Al + Cr)) with respect to the total amount of aluminum and chromium is 0.01 to 0.10 (however, atoms Ratio) aluminum and chromium composite oxide layer,
A surface-coated cutting tool that exhibits excellent chipping resistance in high-speed intermittent cutting of high-hardness steel, which is formed by chemical vapor deposition of the hard coating layer configured as described above in (a) to (c). The surface-coated cutting tool according to claim 1,
The lower layer composed of the composite carbonitride layer of titanium and chromium in (a) above,
Using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal grain is normal to the surface polished surface. The tilt angle formed by the normal of the {112} plane, which is the crystal plane, is measured, and, among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. An inclination angle frequency distribution graph that occupies a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution graph,
The surface-coated cutting tool according to claim 1. The surface-coated cutting tool according to claim 1,
The upper layer made of the composite oxide layer of aluminum and chromium in (c) is
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane, is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. An inclination angle frequency distribution graph that occupies a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution graph,
The surface-coated cutting tool according to claim 1. The surface-coated cutting tool according to claim 1,
The lower layer composed of the composite carbonitride layer of titanium and chromium in (a) above,
Using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal grain is normal to the surface polished surface. The tilt angle formed by the normal of the {112} plane, which is the crystal plane, is measured, and, among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. An inclination angle frequency distribution graph in which the sum of the frequencies is 45% or more of the entire frequency in the inclination angle frequency distribution graph,
The upper layer made of the composite oxide layer of aluminum and chromium in (c) is
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane, is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. An inclination angle frequency distribution graph that occupies a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution graph,
The surface-coated cutting tool according to claim 1. The surface-coated cutting tool according to claim 1,
Between the surface of the tool base and the lower layer made of the titanium and chromium composite carbonitride layer of (a), a Ti carbide layer having a total average layer thickness of 0.1 to 5 μm, and nitriding Interposing an adhesive Ti compound layer formed by chemical vapor deposition consisting of one or more of a physical layer, a carbonitride layer, a carbonate layer, and a carbonitride layer,
The surface-coated cutting tool according to any one of claims 1 to 4, wherein:

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