JP6385243B2 - Coated cutting tool - Google Patents

Description

  The present invention relates to a coated cutting tool coated with a hard coating applied to, for example, cutting of high-hardness steel or super heat-resistant alloy.

  Conventionally, in order to improve the durability of a cutting tool, a coated cutting tool coated with a hard film by an arc ion plating method has been widely applied. Among hard coatings, composite nitride coatings of Al and Ti (hereinafter sometimes referred to as AlTiN) are widely applied because they have excellent wear resistance. Usually, AlTiN tends to have higher heat resistance when the content of Al is large. However, it is known that when the Al content is excessively increased, the hardness decreases because AlN having a fragile hcp structure (hcp structure: hexagonal close-packed structure) increases. For example, Patent Document 1 discloses that the hardness of AlTiN starts to decrease when the Al content ratio (atomic%) is 60% or more with respect to the total amount of metal elements.

  On the other hand, in Patent Document 2, in order to supplement the decrease in wear resistance of AlTiN accompanying an increase in Al content, AlTiN having a high Al content and AlTiN having a low Al content are alternately laminated, A coated cutting tool in which the overall composition of the laminated film is Al-rich is disclosed. Patent Document 2 discloses that the durability of a tool can be improved by applying an interlaminar film as compared with AlTiN made of a single layer film.

JP-A-8-209333 JP-A-11-216601

In recent years, high-speed machining of high-hardness steel, super heat-resistant alloys, and the like has been demanded, and the usage environment of cutting tools has become more severe. In particular, when machining difficult-to-cut materials such as cold tool steel and Ni-base superheat-resistant alloy adjusted to a high hardness of 60 HRC or higher by heat treatment, peeling of the tool and progress of tool wear tend to occur at an early stage. In such a difficult-to-cut material, the coated cutting tool coated with a single-layer coating or an inter-laminate coating as described in Patent Documents 1 and 2 has not been sufficiently improved in durability.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coated cutting tool that is excellent in durability in processing of a high hardness cold tool steel, a super heat resistant alloy, or the like.

  The inventor of the present invention has a large compositional difference between the individual films of the multi-layered film even if the Al content ratio is increased in the overall composition of the multi-layered film in the multi-layered film made of AlTi-based nitride or carbonitride. In some cases, it was confirmed that the tool life was shortened. Then, the present inventors have found that there is a specific film structure showing excellent durability even in the cutting of high-hardness steel and super heat-resistant alloy, and have reached the present invention.

That is, the present invention includes a base material, an a layer that is disposed on the base material, the nanobeam diffraction pattern is indexed to the crystal structure of WC, and is composed of a carbide containing W and Ti, and the a layer. And the a layer has a film thickness of 1 nm or more and 10 nm or less,
The mutual laminated film includes an Al and Ti nitride or carbonitride b layer having an Al content ratio (atomic%) of 50% to 70% with respect to the total amount of metal elements (including metalloid). ,
Al with 70% or more of Al content (atomic%) with respect to the total amount of metal elements (including metalloids) and c layers made of Ti nitride or carbonitride are alternately formed. ,
It is a coated cutting tool in which the difference in the Al content ratio (atomic%) between the b layer and the c layer is 10% or more and 30% or less.

The individual film thicknesses of the b layer and the c layer are preferably 50 nm or less.
A d layer made of nitride or carbonitride having a composition different from that of the b layer or the c layer may be provided on the mutual laminated film. The d layer has a Ti content (atomic%) of 60% to 80% and a Si content (atomic%) of 20% to 40% with respect to the total amount of metal elements. It is preferable that

  According to the present invention, it is possible to greatly improve the durability of a coated cutting tool even when a cold tool steel, a Ni-base superalloy and the like adjusted to a high hardness of 60 HRC or higher are processed by heat treatment. Furthermore, even if it uses for cutting of SUS material etc. which are easy to generate | occur | produce welding, the outstanding durability is shown. Therefore, it is possible to realize an improvement in machining efficiency and a reduction in machining cost in a wide range of workpieces.

  According to the inventor's study, increasing the Al content in AlTi-based nitrides or carbonitrides not only increases the heat resistance of the coating itself, but also welds it to the tool edge during processing. It was confirmed that the cutting resistance was reduced. However, when the content of Al contained in the AlTi nitride or carbonitride increases, the content of AlN having a fragile hcp structure increases, so that the durability of the tool tends to decrease. Therefore, in the present invention, when the study was made to increase the Al content contained in the hard coating without reducing the durability of the tool, an AlTi nitride or carbonitride having a specific composition was laminated to each other. It was confirmed that AlN having an hcp structure is hardly formed. And in order to improve the durability of the coated cutting tool, it is important to control the compositional difference between the individual films of the mutual laminated film, and the present invention has been found by finding a specific film structure with excellent durability. Reached. Hereinafter, the configuration requirements of the present invention will be described.

The mutual laminated film of the present invention comprises an Al content ratio (atomic%) of 50% to 70% with respect to the total amount of metal elements, a b layer made of a nitride of Al and Ti or carbonitride, and a metal element. Al having an Al content ratio (atomic%) of 70% or more and c layers made of Ti nitride or carbonitride are alternately formed with respect to the total amount.
The b layer is a film for making the main body of the crystal structure of the mutual laminated film an fcc structure (fcc structure: face-centered cubic lattice structure). When the Al content ratio (atomic%) of the b layer is larger than 70%, the AlN of the hcp structure contained in the entire multilayer coating increases and the durability of the tool decreases. However, if the Al content ratio (atomic%) of the b layer is less than 50%, the Al content contained in the whole of the multilayer coating is reduced, so that the heat resistance is lowered and the tool blade edge is reduced. There is a tendency that the welding resistance increases and the cutting resistance during processing also increases.
In order to improve the durability of the coated cutting tool with the crystal structure as the main component of the fcc structure while increasing the Al content ratio (atomic%) in the mutual laminated film, the b layer of the present invention is made of Al with respect to the total amount of metal elements. Al and Ti nitride or carbonitride having a content ratio (atomic%) of 50% or more and 70% or less is used.

  The b layer preferably has an Al content (atomic%) of 65% or less. Further, the Al content ratio (atomic%) is preferably 60% or less. In order that the crystal structure of the mutual laminated film is mainly composed of the fcc structure, the b layer preferably has a Ti content (atomic%) of 30% or more with respect to the total amount of metal elements. The b layer preferably has a Ti content of 35% or more, and more preferably 40% or more.

The c layer is a film for increasing the Al content ratio (atomic%) of the mutual laminated film. When the Al content ratio (atomic%) of the c layer is reduced, the Al content is reduced in the entire multilayer coating, and therefore the cutting resistance during processing tends to increase. Therefore, the c layer is made of Al or Ti nitride or carbonitride having an Al content ratio (atomic%) of 70% or more with respect to the total amount of metal elements. By setting the Al content ratio (atomic%) of the c layer to 70% or more, the Al content is increased in the overall composition of the mutual laminated coating, and welding to the tool edge during cutting is suppressed, thereby reducing the cutting resistance. Can be reduced.
The c layer preferably has a Ti content (atomic%) of 5% or more with respect to the total amount of metal elements in order to improve the wear resistance of the multilayered coating. Furthermore, the Ti content ratio (atomic%) is preferably 10% or more.

  The present inventor has found that even if the crystal structure of the mutual laminated film has an fcc structure, if the difference in the Al content ratio (atomic%) of the b layer and the c layer increases, the difference in the lattice constant of each layer increases. It was confirmed that the durability of the tool was lowered due to difficulty in maintaining the continuity between the layer and the c layer. According to the study of the present inventor, the difference in the Al content ratio (atomic%) between the b layer and the c layer is 30% or less, so that the consistency of the lattice constant of each layer is increased and excellent durability is exhibited. I confirmed that I can do it. In addition, if the difference in the Al content ratio (atomic%) between the b layer and the c layer is reduced, the fragile hcp-structured AlN increases and the durability of the tool decreases. The difference in content ratio (atomic%) is set to 10% or more.

It is preferable to control the difference in the Al content ratio between the b-layer and the c-layer, and to make the individual film thicknesses in the multilayered coating less than a certain value. When the individual film thicknesses of the b layer and the c layer are increased, the AlN of the hcp structure tends to increase and the durability of the tool tends to be lowered. For this reason, the individual film thicknesses of the b layer and the c layer are preferably 50 nm or less. A more preferable film thickness is 20 nm or less. In order to further stabilize the tool performance, the individual film thicknesses of the b layer and the c layer are preferably 5 nm or more, and more preferably 10 nm or more.
The b layer and the c layer are more preferably nitrides which are film types with excellent heat resistance. Further, by making the thickness of the b layer thicker than that of the c layer, the crystal structure of the mutual laminated film tends to be mainly the fcc structure.

The overall composition of the mutual laminated coating is preferably such that the Al content ratio (atomic%) is 60% or more with respect to the total amount of metal elements. The Al content ratio (atomic%) is preferably 65% or more, and more preferably 70% or more. Further, the overall composition of the mutual laminated film is preferably such that the Al content ratio (atomic%) is 85% or less, and more preferably Al is 80% or less.
If the peak intensity corresponding to the fcc structure is the maximum in the crystal structure specified by X-ray diffraction or the like, the peak resulting from the hcp structure may be confirmed. In the present invention, “mainly fcc structure” means that, for example, the peak intensity corresponding to the fcc structure is maximum in X-ray diffraction. When it is difficult to identify a crystal structure by X-ray diffraction, the crystal structure can be identified by a limited field diffraction method using a transmission electron microscope (TEM).

  The b layer and c layer of the present invention are one or two selected from Group 4a (excluding Ti), Group 5a, Group 6a and Si, B of the periodic table with respect to the total amount of metal elements. The total of the elements of the seeds or more can be contained at 10% or less. In addition, if the b layer and the c layer are nitrides or carbonitrides, a part of the film may contain a nonmetallic element such as oxygen.

  There are cases where the effect of improving the durability of the coated cutting tool is small even if the overall film thickness of the mutual laminated film becomes too thin or too thick. Therefore, it is preferable that the total film thickness of the mutual laminated film is 1 μm to 5 μm. In the present invention, a d layer made of a nitride or carbonitride having a composition different from that of the b layer or the c layer may be coated on the upper layer of the mutual laminated film.

  The d layer has a Ti content (atomic%) of 60% or more and 80% or less, and a Si content (atomic%) of 20% or more in order to achieve superior durability in cutting of hard steel. It is preferably 40% or less of nitride or carbonitride. By providing a d layer having a composition having a high compressive residual stress, wear resistance tends to be improved even in a severe use environment, and damage to the tool tends to be suppressed. The d layer is more preferably a nitride which is a film type with excellent heat resistance.

The coated cutting tool of the present invention can apply a WC-based cemented carbide to a substrate. And in order to exhibit the effect of the mutual laminated film mentioned above, it is necessary to provide a special layer between the base material and the mutual laminated film. That is, the durability of the coated cutting tool is provided by providing a layer of carbide that is disposed on the substrate, the nanobeam diffraction pattern is indexed to the crystal structure of WC, and contains W (tungsten) and Ti (titanium). Has been confirmed to be significantly improved.
If the a layer has a nanobeam diffraction pattern indexed to the crystal structure of WC and a carbide containing W, it is considered that the affinity with the WC-based cemented carbide, which is the base material, becomes strong and the adhesion is excellent. In addition, it is considered that the durability of the tool is improved because the a-layer contains Ti, so that the laminated film easily has an fcc crystal structure. The a layer preferably has a Ti content ratio (atomic%) of 10% to 25% with respect to the total amount of metal elements.
However, if the a layer becomes too thin or too thick, it is not sufficient to improve the adhesion to the substrate. Therefore, the a layer is 1 nm or more and 10 nm or less. The a layer is preferably 2 nm or more. The a layer is preferably 5 nm or less.

The a layer may contain a film component and a base material component in addition to W and Ti. For example, the a layer may include the components Co contained in the base material and Al or N of the b layer, but the a layer has a nanobeam diffraction pattern indexed to the WC crystal structure and contains W and Ti. The effect of this invention is exhibited by using a carbide.
The a layer can be confirmed by cross-sectional observation, composition analysis, and nanobeam diffraction pattern of the tool edge by observation with a transmission electron microscope.

  It is preferable to directly coat the laminated film directly on the a layer, but between the a layer and the laminated film, a hard film made of nitride or carbonitride having a composition different from that of the b layer or c layer is formed. It may be provided. In this case, the film thickness of the hard film provided between the a layer and the mutual laminated film is preferably 1 μm or less, and more preferably 0.5 μm or less.

In order to form the a layer of the present invention, Ti bombardment is preferably carried out using a cathode having a magnetic field configuration in which a coil magnet is provided on the outer periphery of the target to confine the arc spot inside the target. By using such a cathode and bombarding with Ti, which is an element species that easily forms carbides, the oxide on the substrate surface is removed and cleaned, and the bombarded Ti ions are converted into WC on the substrate surface. And the nanobeam diffraction pattern is indexed to the crystal structure of WC, and carbides containing W and Ti are easily formed.
Further, when the negative bias voltage applied to the base material during Ti bombardment and the current applied to the target are low, carbides containing W and Ti are hardly formed. Therefore, the negative bias voltage applied to the substrate is preferably −1000 V to −700 V. Further, the current supplied to the target is preferably 80A to 180A.
Bombarding may be carried out while introducing argon gas, nitrogen gas, hydrogen gas, hydrocarbon-based gas, etc., but the substrate is formed by carrying out the furnace atmosphere under a vacuum of 1.0 × 10 ⁻² Pa or less. It is preferable because the surface is cleaned and a diffusion layer is easily formed.

  The coated cutting tool of the present invention is particularly effective when applied to a tool such as a radius end mill or a square end mill that mainly uses an outer peripheral blade. Moreover, it is preferable that the base material of the coated cutting tool has a hardness of 91.0 HRA or more and 94.5 HRA or less. When the hardness of the substrate is lower than this, the wear resistance may be lowered. Moreover, when the hardness of a base material becomes higher than this, toughness may fall.

Using a solid end mill made of a WC-based cemented carbide and an insert type end mill as a base material, a coated cutting tool was prepared by coating a hard film under each condition, and its characteristics were evaluated. An arc ion plating film forming apparatus was used for forming the hard film. A bias power source was connected to the base material installed in the vacuum vessel, and a negative DC bias voltage was applied to the base material to coat the hard film.
Table 1 shows cathodes and bias conditions used for film formation. In order to cover the b layer and the c layer of the present invention, permanent magnets were provided on the outer periphery and the back surface of the target, and cathodes having an average magnetic flux density of 20.2 mT (hereinafter referred to as C1 and C2) were used. In the metal bombardment treatment, a cathode (hereinafter referred to as C3) having a coil magnet provided on the outer periphery of the target was used.

The substrate was fixed to a pipe-shaped jig in a vacuum vessel, heated and degassed in a vacuum of about 500 ° C. and 1 × 10 ⁻³ Pa, and then cleaned with Ar plasma. And it vacuum-evacuated so that it might become 8 * 10 < ^-3 > Pa or less, The arc current of 150 A was supplied to C3, and Ti bombarding process was implemented for 4 minutes.
Thereafter, nitrogen gas was introduced into the furnace, power was applied to C1, and a hard film made of nitride was coated with a thickness of about 300 nm. Thereafter, power is applied to C1 and C2 so that the individual film thicknesses of the b layer and the c layer become 20 nm, and a mutual laminated film of about 2.5 μm is coated, and Examples 1 to 3 of the present invention and comparative examples 1 was produced.
Comparative Examples 2 to 4 were prepared by coating about 2.5 μm of AlTi nitride composed of a single layer coating.

  A TEM analysis was performed by processing an insert-type end mill for analysis using a field emission transmission electron microscope (model number: JEM-2010F type) manufactured by JEOL Ltd. The composition analysis of each layer (a layer, b layer, c layer) was obtained by analyzing with a beam diameter of 1 nm using an attached UTW type Si (Li) semiconductor detector. Further, in order to confirm the crystal structure of the a layer, nanobeam diffraction was performed with a camera length of 50 cm and a beam diameter of 2 nm or less.

From the EDS spectrum analysis results, it was confirmed that the layer a of the present invention example contained the largest amount of W in the metal element content ratio (atomic%), and then contained a large amount of Ti. The content ratio (atomic%) of W was about 80% with the content ratio (atomic%) of the metal element. The Ti content ratio (atomic%) was about 15%. In addition to W and Ti, Al and N, which are hard film components, were contained. Further, Co, which is a base material component, was also slightly contained. The a layer of the present invention example could be indexed to the WC crystal structure from the nanobeam diffraction pattern.
From the EDS spectrum analysis and the nanobeam diffraction pattern, it was confirmed that the layer a of the example of the present invention was indexed to the crystal structure of WC and was a carbide containing tungsten (W) and titanium (Ti). The film thickness of the a layer was obtained from an average of 5 fields or more in cross-sectional observation. In any sample, it was confirmed that the film thickness of the a layer was 3 nm.

Using an electronic probe microanalyzer device (model number: JXA-8500F) manufactured by JEOL Ltd., the total composition of the mutual laminated coating was measured by the attached wavelength dispersion electron probe microanalysis (WDS-EPMA). This film composition was analyzed by processing an insert type end mill for analysis and observing a cross section, and measuring each layer at five points with an acceleration voltage of 10 kV, an irradiation current of 5 × 10 ⁻⁸ A, an acquisition time of 10 seconds, and an analysis region diameter of 1 μm. Then, the composition was determined from the average.

  Film hardness was measured using a nanoindentation device (model number: ENT-1100a) manufactured by Elionix Corporation. This hardness measurement is carried out by measuring 10 points from the surface of the insert type end mill for analysis under the measurement conditions of an indentation load of 49 mN, a maximum load holding time of 1 second, and a removal speed after loading of 0.49 mN / second. Asked. Before the measurement, single crystal Si as a standard sample was measured, and it was confirmed that its hardness was 12 GPa.

  The crystal structure of the film was measured using an X-ray diffractometer (model number: RINT2500V-PSRC / MDG) manufactured by Rigaku Corporation. This X-ray diffraction was carried out by using an insert type end mill for analysis under measurement conditions of a tube voltage of 40 kV, a tube current of 300 mA, an X-ray source Cukα (λ = 0.15418 nm), and 2θ of 30 to 70 degrees. Each analysis result is shown in Table 2.

In Examples 1 and 2 of the present invention, peaks attributed to the fcc structure and the hcp structure were confirmed from X-ray diffraction, and the peak attributed to the fcc structure showed the maximum intensity. In Invention Example 3, only a peak attributed to the fcc structure was confirmed from X-ray diffraction.
In Comparative Examples 1 to 3, the peak due to the fcc structure and the hcp structure was confirmed from the X-ray diffraction, and the peak due to the hcp structure showed the maximum intensity. Although the Al content ratios of the entire coatings of Invention Example 1 and Comparative Example 3 are about the same, Invention Example 1 as an interlaminar film is mainly composed of an fcc structure, while Comparative Example 3 which is a single-layer film is The hcp structure was the main component.
In Comparative Example 4, only the peak due to the fcc structure was confirmed from the X-ray diffraction.
Inventive Example 3 and Comparative Example 4 in which the peak intensity due to the hcp structure was not confirmed were higher in hardness than other samples.

Using the coated cutting tool coated with the hard coating shown in Table 2, a cutting test was performed under the following conditions. The test results are shown in Table 3.
<Cutting test condition 1>
Tool: Solid end mill φ10 × 2 flute (HES2100 manufactured by Hitachi Tool Co., Ltd.)
Base material: WC (bal.)-Co (11 mass%)-TaC (0.4 mass%)-Cr ₃ C ₂ (0.9 mass%), WC average particle diameter 0.6 μm, hardness 92.4HRA Cemented carbide cutting method: side cutting Work material: Ni-19% Cr-18.7% Fe-3.0% Mo-5.0% (Nd + Ta) -0.8% Ti-0. Ni-based alloy having a composition of 5% Al-0.03% C (age-hardened)
Cutting depth: 6mm in the axial direction, 0.3mm in the radial direction
Cutting speed: 40 m / min
Single blade feed rate: 0.04mm / tooth
Cutting oil: Water-soluble cutting oil Cutting distance: 0.2m

<Cutting test condition 2>
Tool: Insert type radius end mill φ12 × R2 × 3 flute (manufactured by Hitachi Tool Co., Ltd.)
Substrate: The composition is WC (bal.)-Co (8 mass%)-TaC (0.25 mass%)-Cr ₃ C ₂ (0.9 mass%), and the WC average particle diameter is 0.6 μm, Cemented carbide with a hardness of 93.4HRA Cutter Model Number: ASRM-1012R-3-M6
Insert model number: EPHN0402TN-2
Cutting method: Bottom cutting Work material: SKD11 (60HRC)
Cutting depth: 0.15mm in the axial direction, 6mm in the radial direction
Cutting speed: 180 m / min
Single blade feed rate: 0.4 mm / tooth
Cutting oil: Air blow Cutting distance: 25m

<Cutting test condition 3>
Tool: Insert type radius end mill φ32 × R8 × 5 flute (manufactured by Hitachi Tool Co., Ltd.)
Substrate: The composition is WC (bal.)-Co (8 mass%)-TaC (0.25 mass%)-Cr ₃ C ₂ (0.9 mass%), and the WC average particle diameter is 0.6 μm, Cemented carbide with a hardness of 93.4HRA Cutter Model Number: ASRS2032R-5
Insert model number: EPMT0603EN-8LF
Cutting method: Bottom cutting Work material: SUS304 (180HB)
Cutting depth: 0.5mm in the axial direction, 22mm in the radial direction
Cutting speed: 180 m / min
Single blade feed: 0.5mm / tooth
Cutting oil: Air blow Cutting distance: 12.5m

Examples 1 to 3 of the present invention are mutual laminated films having a high Al content and mainly an fcc structure, have low cutting resistance, and suppress wear of the tool edge. In particular, Example 1 of the present invention had a small cutting resistance due to a large amount of Al contained in the entire laminated film, and the tool edge was less worn.
Comparative Example 1 is a mutual laminated film mainly composed of an fcc structure having a large Al content, but the consistency between the b layer and the c layer is poor due to a large difference in the Al content of the individual films constituting the mutual laminated film. The film was unable to withstand the mechanical load during cutting, and was damaged due to fracture.
Comparative Examples 2 and 3 were single-layer coatings mainly composed of hcp structures, and the coatings were not able to withstand the mechanical load during cutting and were damaged due to damage.
Comparative Example 4 had a stable fcc structure and high hardness, but the Al content in the film was small, so that the cutting resistance was higher and the tool wear was larger than in the inventive example.

In Example 2, a sample was prepared using the cathode shown in Table 4.
In Example 20 of the present invention, after Ti bombardment, nitrogen gas was introduced into the furnace, and power was applied to C1 and C2 so that each film thickness was 20 nm. The laminated film was coated directly.
In Invention Example 21, after Ti bombarding, nitrogen gas was introduced into the furnace, power was applied to C1, and a hard film made of a nitride of about 300 nm was coated, and then the individual film thickness became 20 nm. Thus, electric power was applied to C1 and C2 to coat a laminated film of about 2.5 μm.
In Example 22 of the present invention, after Ti bombarding, nitrogen gas was introduced into the furnace, power was applied to C2, and a hard film made of a nitride of about 300 nm was coated, and then the individual film thickness became 20 nm. Thus, electric power was applied to C1 and C2 to coat a laminated film of about 2.5 μm.
In Comparative Example 20, without cleaning with Ti bombardment, nitrogen gas was introduced into the furnace after cleaning with Ar plasma, and power was supplied to C1 and C2 so that the individual film thickness was 20 nm directly above the substrate. Was applied to coat a laminated film of about 2.5 μm.
Then, the cutting test was performed under the same conditions as the condition 3 of Example 1. The test results are shown in Table 5.

All of the examples of the present invention which were the mutual laminated films provided with the a layer exhibited excellent durability. In particular, Example 20 of the present invention in which an individual laminated film having an individual film thickness of 50 nm or less was provided immediately above the a layer tended to reduce the maximum wear width of the tool edge.
Invention Examples 21 and 22 are film structures in which a b layer or a c layer having a film thickness of 200 nm is provided between the a layer and the mutual laminated film having an individual film thickness of 50 nm or less, but the a layer is provided. It was confirmed that the maximum wear width was smaller than that of the comparative example without.
On the other hand, in Comparative Example 20, the mutual laminated film is the same as Example 20 of the present invention, but since the a layer was not provided, the maximum wear width of the tool blade edge was increased.

In Example 3, for Inventive Examples 1 and 3 and Comparative Example 3 evaluated in Example 1, a sample in which about ₇₅ μm of Ti ₇₅ Si ₂₅ N (the numerical value is an atomic ratio) is provided on the mutual laminated film is prepared. did.
A sample in which Ti ₇₅ Si ₂₅ N was provided on Invention Example 1 was designated as Invention Example 30. A sample in which Ti ₇₅ Si ₂₅ N was provided on Invention Example 3 was designated as Invention Example 31. A sample in which Ti ₇₅ Si ₂₅ N was provided on Comparative Example 3 was designated as Comparative Example 30. And it evaluated on the test conditions similar to Example 1. FIG.
The test results are shown in Table 6.

It was confirmed that when the d layer as the protective film was provided on the mutual laminated film of the example of the present invention, the maximum wear width at the initial stage of processing was suppressed as compared with the case where the protective film was provided on the single layer of AlTiN. . It is presumed that the effect of improving the tool life is further exhibited by applying the present invention example provided with the d layer to more severe processing conditions.

Claims (4)

A substrate, an a layer made of a carbide containing W and Ti, wherein the nanobeam diffraction pattern is indexed to a WC crystal structure, and an interlaminate disposed on the a layer And having a film
The a layer has a thickness of 1 nm or more and 10 nm or less,
The mutual laminated film includes an Al and Ti nitride or carbonitride b layer having an Al content ratio (atomic%) of 50% to 70% with respect to the total amount of metal elements (including metalloid). ,
Al with 70% or more of Al content (atomic%) with respect to the total amount of metal elements (including metalloids) and c layers made of Ti nitride or carbonitride are alternately formed. ,
The coated cutting tool whose difference of the Al content rate (atomic%) of the said b layer and the said c layer is 10% or more and 30% or less.   The coated cutting tool according to claim 1, wherein the film thickness of each of the b layer and the c layer is 50 nm or less.   The coated cutting tool according to claim 1 or 2, wherein a d layer made of a nitride or carbonitride having a composition different from that of the b layer or the c layer is provided on the mutual laminated film. The d layer has a Ti content ratio (atomic%) of 60% to 80% and an Si content ratio (atomic%) of 20% to 40% with respect to the total amount of metal elements (including metalloids). The coated cutting tool according to claim 3, which is a nitride or a carbonitride.