WO2017142061A1

WO2017142061A1 - Surface coated cutting tool

Info

Publication number: WO2017142061A1
Application number: PCT/JP2017/005901
Authority: WO
Inventors: 正樹奥出; 西田　真; 翔龍岡; 佐藤　賢一; 光亮柳澤
Original assignee: 三菱マテリアル株式会社
Priority date: 2016-02-17
Filing date: 2017-02-17
Publication date: 2017-08-24

Abstract

A surface coated cutting tool with a hard coating layer formed on a tool base body surface thereof, said hard coating layer comprising at least a lower layer and an upper layer, wherein the lower layer comprises a Ti compound layer, said Ti compound layer having a total average layer thickness of 2-15μm and comprising one or more layers selected from a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, at least one of said layer(s) being a TiCN layer, the upper layer comprises an Al₂O₃ layer having an average layer thickness of 1-15μm, at least one of the TiCN layer(s) making up the lower layer demonstrates a maximum diffraction peak intensity at the (200) plane during X-ray diffraction and has an orientation index Tc(200) of 2.0 or greater, and in the lower layer, crystal grains that have a columnar, vertically elongated structure with an aspect ratio of 5 or greater preferably occupy 70% or more of the area of a vertical cross-section of the lower layer.

Description

Surface coated cutting tool

The invention of the present application has excellent plastic deformation resistance that the hard coating layer has excellent even when the hard coating layer is subjected to cutting under high load and low speed conditions in which the hard coating layer easily causes plastic deformation. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent wear resistance over the use of the above.
This application claims priority based on Japanese Patent Application No. 2016-027727 filed in Japan on February 17, 2016 and Japanese Patent Application No. 2017-026575 filed on February 16, 2017 in Japan. Is hereby incorporated by reference.

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) 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). And a Ti compound layer composed of one or more of a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) The upper layer is an aluminum oxide layer (hereinafter referred to as an Al ₂ O ₃ layer),
Although a coated tool in which the hard coating layer composed of (a) and (b) is formed by vapor deposition is known, the chipping resistance, chipping resistance, Various proposals have been made to improve tool performance such as peelability and wear resistance.

For example, in Patent Document 1, a composite hard layer composed of a titanium compound inner layer including at least one titanium carbonitride layer and an aluminum oxide outer layer is coated on the surface of a WC-based cemented carbide substrate. In the cutting tool, at least one titanium carbonitride layer constituting the titanium compound inner layer is a TiCN layer in which a maximum peak by X-ray diffraction appears on the (220) plane, and the aluminum oxide outer layer is a κ type Occurrence of abnormal damage due to exfoliation, wear, etc. by using an aluminum oxide layer that is mainly composed of crystals and has a maximum peak on the surface defined as 2.79 angstroms of κ-Al ₂ O _{3 in} ASTM. It has been proposed to prevent tooling and improve tool life.
That is, since the TiCN layer is oriented in the (220) plane, the adhesion with the substrate or the underlying layer is increased, and peeling from the interface is less likely to occur. be able to. Further, on the TiCN layer oriented in the (220) plane, an oxidation in which a maximum peak appears on a plane mainly composed of κ-type crystals and defined as a plane having a plane spacing of 2.79 Å in κ-Al ₂ O _{3 in} ASTM. When the aluminum layer is coated, the surface of the κ-Al ₂ O ₃ having an orientation of 2.79 angstroms between the surfaces is smooth and the surface of the coating layer is smooth, so that abnormal damage due to friction between the chips and the tool is less likely to occur. The aluminum oxide layer is resistant to abnormal damage and exhibits stable wear resistance.

Further, in Patent Document 2, in a coated tool in which an inner layer and an outer layer are formed on the tool base surface, the inner layer has a multilayer structure having a titanium carbonitride layer having a thickness of 10 μm or more and having a columnar structure, and the outer layer is at least The layer includes an α-type aluminum oxide layer, and the orientation index TC (422) and TC (311) of the (422) plane and the (311) plane are both 1.3 or more and 3 or less for the titanium carbonitride layer. By providing orientation, and by making all orientation indices TC (hkl) excluding the orientation indices TC (422) and TC (311) to be 1.5 or less, the peel resistance and wear resistance of the coated tool It has been proposed to improve crater resistance and breaking strength.
Here, the orientation index TC (422) and TC (311) of the titanium carbonitride layer are both 1.3 or more, and the structure is a columnar structure, so that the fracture resistance of the film can be improved even with a film thickness of 10 μm or more. It is possible to greatly improve the wear resistance, and the progress of wear due to chipping during cutting can be suppressed, and the welding of the work material during cutting is less likely to occur. Since the increase in stress can be prevented, the peel resistance is also greatly improved.

Patent Document 3 discloses that in a coated tool in which a hard coating layer including at least one titanium carbonitride layer is formed on a substrate surface, an orientation index out of the texture coefficient TC (hkl) of the titanium carbonitride layer. When TC (220) is the maximum, the indentation hardness of the hardness reference piece is Hs, and the indentation hardness of the titanium carbonitride layer is Ht, (average value of Ht) / Hs ≧ 3 and the titanium carbonitride layer When the maximum value of the indentation hardness is Htmax and the minimum value is Htmin, (Htmax−Htmin) / (average value of Ht) <0.5, the crystal orientation of the titanium carbonitride layer is controlled, and the carbon It has been proposed to improve the wear resistance and fracture resistance of the coated tool by eliminating variations in the hardness of the titanium nitride layer.

Japanese Laid-Open Patent Publication No. 8-300203 (A) Japanese Patent No. 11-140647 (A) Japanese Patent No. 5729777 (B)

The performance of cutting equipment has been remarkable in recent years. On the other hand, there is a strong demand for labor saving and energy saving and cost reduction for cutting. Along with this, the cutting work becomes more efficient, and there is a tendency that a high load acts on the cutting edge due to heavy cutting such as high cutting and high feed, intermittent cutting, and the like. There is no problem when the above-mentioned conventional coated tool is used for continuous cutting and high-speed cutting under normal conditions such as steel and cast iron. When used in high load / low speed cutting conditions that cause plastic deformation, the plastic deformation of the hard coating layer is likely to cause the crystal grains constituting the hard coating layer to fall off, resulting from this. Abnormal wear tends to progress, and this causes a problem that tool life is reached in a relatively short time.

In view of the above, the inventors of the present invention have a high load acting on the cutting edge, and even when the hard coating layer is used under a high load / low speed cutting process condition in which plastic deformation easily occurs, As a result of earnest research on the structure of the hard coating layer that is unlikely to cause abnormal damage, the hard coating layer is composed of a lower layer made of a Ti compound layer and an upper layer made of an Al ₂ O ₃ layer, and the lower layer is made of When at least one Ti carbonitride (hereinafter also referred to as “TiCN”) layer is provided as a constituent Ti compound layer, and the (200) orientation of the TiCN layer is increased, Even when a load (especially a large shearing force on the surface of the TiCN layer) is applied, the TiCN layer exhibits excellent plastic deformation resistance. As a result, abnormal damage due to dropping off of crystal grains constituting the TiCN layer is caused. Suppress Rukoto, also is was found that thereby obtaining aims to improve the wear resistance.
In addition, when the TiCN layer is formed as a columnar vertically long structure having an aspect ratio of 5 or more, in addition to excellent plastic deformation resistance, it exhibits excellent wear resistance provided by the columnar vertically long structure. I found it.

This invention is made | formed based on the said knowledge, Comprising: It has the following aspects.
(1) In a surface-coated cutting tool in which a hard coating layer is formed on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
(A) The hard coating layer comprises at least a lower layer and an upper layer,
(B) The lower layer is composed of one layer or two or more layers selected from a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride oxide layer, and at least one of them is A Ti compound layer composed of Ti carbonitride layers and having a total average layer thickness of 2 to 15 μm,
(C) the upper layer comprises an aluminum oxide layer having an average layer thickness of 1 to 15 μm;
(D) In at least one Ti carbonitride layer in the Ti compound layer of the lower layer, the maximum diffraction peak intensity by X-ray diffraction appears on the (200) plane, and the orientation index Tc (200) is A surface-coated cutting tool characterized by being 2.0 or more.
(2) In the longitudinal section of the Ti compound layer, the area ratio occupied by the crystal grains having a columnar longitudinal structure having an aspect ratio of 5 or more is 70 area% or more. Coated cutting tool.
(3) The surface-coated cutting tool according to (1) or (2), wherein in the Ti compound layer, the thickness of all Ti carbonitride layers is 1.5 to 12 μm.

Next, the coated tool according to one aspect of the present invention (hereinafter referred to as “the coated tool of the present invention”) will be described in detail.
The hard coating layer of the coated tool of the present invention is composed of at least a lower layer made of a Ti compound layer and an Al ₂ O ₃ layer to an upper layer.

Lower layer:
The lower layer composed of a Ti compound layer (for example, a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer) gives high temperature strength to the hard coating layer due to its excellent high temperature strength. Further, the Ti compound layer is in close contact with both the tool base surface and the upper layer composed of the Al ₂ O ₃ layer, and has an action of maintaining the adhesion of the hard coating layer to the tool base.
However, when the total average layer thickness of the Ti compound layer is less than 2 μm, the above-described effects cannot be sufficiently exhibited.
On the other hand, the lower layer of the present invention has excellent plastic deformation resistance as will be described later. However, when the total average layer thickness of the lower layer exceeds 15 μm, plastic deformation is caused by a high load acting during cutting. As a result, crystal grains fall off, thereby causing chipping, chipping, peeling, or abnormal damage such as progression of uneven wear.
Therefore, in the coated tool of the present invention, the total average layer thickness of the lower layer made of the Ti compound layer is set to 2 to 15 μm.

Lower TiCN layer:
As described above, the lower layer of the hard coating layer of the coated tool of the present invention is composed of a Ti compound layer, and the lower layer includes at least one TiCN layer, and the layer has (200) orientation. The TiCN layer is configured as follows.
That is, when the diffraction peak intensity from each crystal lattice plane is measured by X-ray diffraction for the crystal grains constituting the at least one TiCN layer of the lower layer, the maximum diffraction peak intensity appears on the (200) plane ( 200) It has orientation.
FIG. 1 shows an example of a chart of diffraction peak intensity from each crystal lattice plane measured by X-ray diffraction for the TiCN layer of the coated tool of the present invention.
As is clear from FIG. 1, it can be seen that the TiCN layer of the coated tool of the present invention has the maximum diffraction peak intensity with respect to the (200) plane as compared with the peak intensity of other crystal lattice planes.
X-ray diffraction was measured by the 2θ-θ method using CuKα rays using a Spectris PANalytical Empire as an X-ray diffractometer, and measurement conditions (measurement range (2θ): 30 to 130 degrees, X-ray output: The measurement was performed under the conditions of 45 kV, 40 mA, divergent slit: 0.5 degree, scan step: 0.013 degree, measurement time per step: 0.48 sec / step.

Further, when the orientation index Tc (hkl) is determined for the at least one TiCN layer, the coated tool of the present invention has a value of Tc (200) of 2.0 or more, preferably 3.0 or more. It has the (200) orientation shown.
The orientation index Tc (hkl) is defined by the following formula.

In the above formula, I (hkl) represents the peak intensity (diffraction intensity) of the measured (hkl) plane, and I ₀ (hkl) is a JCPDS card (Joint Committee on Powder Diffraction Standards (powder X-ray diffraction standard)). The average value of the powder diffraction intensity of TiC and TiN constituting the (hkl) plane represented is shown. In addition, (hkl) is the eight faces of (111), (200), (220), (311), (222), (331), (420), (422) Indicates the average value of 8 surfaces.

As described above, at least one TiCN layer of the coated tool of the present invention shows the maximum peak intensity by X-ray diffraction on the (200) plane, and the orientation index Tc (200) ≧ 2.0 (200). Due to the orientation, even when a large shearing force is applied to the TiCN layer during cutting, the TiCN layer has plastic deformation resistance. The occurrence of peeling or the occurrence of abnormal damage such as the progression of uneven wear can be suppressed, and the wear resistance can be improved thereby.
However, when the X-ray diffraction peak intensity with respect to the (200) plane cannot be said to be maximum as compared with the diffraction peak intensity from other lattice planes, or the orientation index Tc (200) is less than 2.0. In such a case, since the (200) plane orientation is not sufficient, the plastic deformation resistance improvement effect is not sufficient, and as a result, the particles are prevented from falling off when a high load (high shear force) is applied. It is not possible to suppress the occurrence of chipping, chipping and uneven wear.
Therefore, in the present invention, the X-ray diffraction peak intensity of the (200) plane measured for at least one TiCN layer of the lower layer is maximum compared to the peak intensity of other crystal lattice planes, The orientation index Tc (200) was determined to be 2.0 or more, preferably 3.0 or more.

It is preferable that at least one TiCN layer in the lower layer has a columnar vertically long structure.
In particular, the area ratio of the columnar vertically grown TiCN crystal grains having an aspect ratio of 5 or more determined from the maximum grain width W of the TiCN crystal grains and the maximum grain length L in the layer thickness direction is 70% of the longitudinal sectional area of the TiCN layer. In the case of occupying area% or more, it is possible to expect an excellent effect of improving wear resistance, which is a feature of a columnar vertically long structure.
Note that the maximum grain width W and the maximum grain length L are the columnar vertically grown TiCN crystal grains, when one crystal grain in the longitudinal section of the TiCN layer is measured, the crystal grains in the direction perpendicular to the layer thickness direction. The largest value of the width (short side) is called the maximum particle width W, while the largest value of the crystal grain height (long side) in the layer thickness direction is called the maximum particle length L.
Further, the thickness of the TiCN layer is not particularly limited, but it is desirable that the thickness of all the TiCN layers constituting the Ti compound layer is 1.5 to 12 μm.
This indicates that when the thickness of the TiCN layer is 1.5 μm or more, the value of Tc (200) tends to increase, and the plastic deformation resistance in high-load cutting is improved and the flank wear amount is also reduced. This is because the wear resistance is improved. On the other hand, if the thickness of the TiCN layer exceeds 12 μm, plastic deformation is likely to occur, and abnormal damage due to the progress of uneven wear occurs.

Formation of TiCN layer:
The lower Ti compound layer in this invention is formed as follows, for example.
That is, various Ti compound layers comprising one or more of TiC layer, TiN layer, TiCN layer, TiCO layer, TiCNO layer and TiAlN layer are formed by vapor deposition using a normal chemical vapor deposition apparatus.
Among them, a (200) highly oriented TiCN layer, or a TiCN layer in which a crystal grain having a columnar longitudinal structure having an aspect ratio of 5 or more occupies 70 area% or more of the lower layer longitudinal section is, for example, It can be formed by the vapor deposition method.
Reaction gas composition (volume%): TiCl ₄ 1-5%, CH ₃ CN 0.5-1.5%, N ₂ 25-40%, balance H ₂ ,
Reaction atmosphere temperature: 750 to 850 ° C.
Reaction atmosphere pressure: 5 to 10 kPa
By lowering the reaction atmosphere temperature and lowering the gas concentration ratio as a raw material for the TiCN layer, it becomes easy to form a crystal structure with a high (200) orientation, and the structure tends to have a columnar vertically long structure.
Further, when forming the TiN layer, for example,
Reaction gas composition (volume%): NH ₃ 0.5-2.0%, TiCl ₄ 0.1-0.3%, N ₂ 0-10%, balance H ₂ ,
Reaction atmosphere temperature: 750 to 850 ° C.
Reaction atmosphere pressure: 5 to 8 kPa
By creating under such conditions, it becomes easy to form crystal grains having a columnar longitudinal structure having an aspect ratio of 5 or more.

Upper layer composed of Al ₂ O ₃ layer:
The upper layer of the coated tool of the present invention includes a TiCN layer having a maximum peak intensity by X-ray diffraction on the (200) plane and an orientation index Tc (200) of 2.0 or more. Is formed by vapor-depositing an Al ₂ O ₃ layer having an average layer thickness of 1 to 15 μm by the usual chemical vapor deposition method.
Al ₂ O ₃ has various crystal structures such as α-type, κ-type, and γ-type, but has excellent high-temperature hardness, oxidation resistance, and excellent thermal stability. In view of the above, the Al ₂ O ₃ layer constituting the upper layer is preferably an α-type Al ₂ O ₃ layer having an α-type crystal structure.
For example, when forming an α-type Al ₂ O ₃ layer,
Reaction gas composition (volume%): AlCl ₃ 2-5%, CO ₂ 10-20%, HCl 1-3%, H ₂ S 0-0.15%, balance H ₂ ,
Reaction atmosphere temperature: 850 to 950 ° C.
Reaction atmosphere pressure: 5 to 10 kPa
It is produced under the following conditions.
Further, if the average layer thickness of the upper layer is less than 1 μm, it is not possible to ensure wear resistance over a long period of use, whereas if the average layer thickness exceeds 15 μm, the Al ₂ O ₃ crystal grains are coarse. As a result, in addition to the decrease in high-temperature hardness and strength at high temperatures, the chipping resistance and fracture resistance during high-load cutting, in which a large shearing force acts on the cutting edge, are reduced. Was determined to be 1 to 15 μm.

According to the coated tool of the present invention, the hard coating layer formed on the surface of the tool base includes at least a lower layer made of a Ti compound layer and an upper layer made of an Al ₂ O ₃ layer, and at least one of the lower layers. The layer is composed of a TiCN layer, and the TiCN layer has a maximum diffraction peak intensity due to X-ray diffraction on the (200) plane and the orientation index Tc (200) is 2.0 or more. The layer is excellent in plastic deformation resistance.
As a result, even when used under high-load / low-speed cutting conditions where a large shearing force acts on the TiCN layer surface, the coated tool of the present invention has the ability to drop crystal grains due to the excellent plastic deformation resistance of the TiCN layer. It is possible to suppress the occurrence of abnormal damage such as chipping, chipping and peeling, and combined with the excellent high temperature hardness, oxidation resistance and thermal stability of the upper layer made of Al ₂ O ₃ layer It exhibits excellent wear resistance over a long period of use, and is particularly effective for work materials that are susceptible to wear progress on rake surfaces such as carbon steel and alloy steel.
Furthermore, the wear resistance can be further improved by setting the area ratio of the crystal grains having a columnar longitudinal structure having an aspect ratio of 5 or more in the lower layer to 70 area% or more of the vertical section of the lower layer. The life of the cutting tool can be extended.

An example of the diffraction peak intensity obtained from each crystal lattice plane measured by X-ray diffraction for the TiCN layer of the coated tool of the present invention is shown.

Embodiments of the coated tool of the present invention will be specifically described based on examples.

As raw material powders, WC powder, TiC powder, ZrC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, and Co powder all having an average particle diameter of 1 to 3 μm were prepared. Then, after adding wax, ball mill mixing in acetone for 24 hours, drying under reduced pressure, press-molding into a green compact of a predetermined shape at a pressure of 98 MPa. In a vacuum, vacuum sintering is performed at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour, and after sintering, a tool base a to WC-base cemented carbide having an ISO standard CNMG120408 insert shape is used. Each d was produced.

In addition, as raw material powders, TiCN (TiC / TiN = 50/50 by mass ratio) powder, ZrC powder, TaC powder, Mo ₂ C powder, WC powder, Co powder all having an average particle diameter of 0.5 to 2 μm And Ni powder are prepared, these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and then pressed into a compact at a pressure of 98 MPa. The body was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, a tool base e made of TiCN-based cermet having an insert shape of ISO standard CNMG120212 was produced.

Next, each of the tool bases a to d and the tool base e is charged into a normal chemical vapor deposition apparatus, and under the conditions shown in Tables 3 and 4, as lower layers having the target layer thicknesses shown in Table 6. The Ti compound layer shown in Table 6 was formed by vapor deposition of the Al ₂ O ₃ layer as the upper layer of the target layer thickness shown in Table 6 under the conditions shown in Table 3. Invention coated tools 1 to 13 were produced respectively.
Note that the HT-TiCN layer in Table 3 is a TiCN layer manufactured at a higher reaction atmosphere temperature than the TiCN layer shown in paragraph 0016.
Further, in Table 3, the TiN layer-1 (first layer) and the TiAlN layer are the deposition conditions for the Ti compound layer in which columnar vertically oriented crystal grains having an aspect ratio of 5 or more are likely to be formed.

For comparison purposes, each of the tool bases a to d and the tool base e is loaded into a normal chemical vapor deposition apparatus, and the target layer thicknesses shown in Table 7 are set under the conditions shown in Tables 3 and 5. By forming a Ti compound layer as a lower layer by vapor deposition and then depositing an Al ₂ O ₃ layer as an upper layer having a target layer thickness shown in Table 7 under the conditions shown in Table 3, The comparative example coated tools 1 to 13 shown were produced, respectively.

For the TiCN layers of the lower layers of the inventive coated tools 1 to 13 and the comparative coated tools 1 to 13, the diffraction peak intensity from each lattice plane was measured by X-ray diffraction.
In FIG. 1, the chart calculated | required about this invention coated tool 1 is shown.
X-ray diffraction was measured by the 2θ-θ method using CuKα rays using Spectris PANalytical Empirean as an apparatus.
Measurement conditions are measurement range (2θ): 30 to 130 degrees, X-ray output: 45 kV, 40 mA, diverging slit: 0.5 degrees, scan step: 0.013 degrees, measurement time per step: 0.48 sec / step It is.
From the chart obtained above, it was determined whether or not the diffraction peak intensity from the (200) plane was the maximum with respect to the diffraction peak intensities from other lattice planes.
Tables 6 and 7 show the determination results.

Further, the orientation index Tc (200) was determined based on the measurement result of the diffraction peak intensity.
The orientation index Tc (200) was calculated by the following formula.

Here, I (hkl) represents the measured diffraction peak intensity of the (hkl) plane, and I ₀ (hkl) is represented by a JCPDS card (Joint Committee on Powder Diffraction Standards (powder X-ray diffraction standard)) ( hkl) The average value of the powder diffraction intensities of TiC and TiN constituting the surface is shown. Further, (hkl) is the eight surfaces (111), (200), (220), (311), (222), (331), (420), and (422).
Tables 6 and 7 show the values of the orientation index Tc (200) calculated above.

Further, the longitudinal section of the TiCN layer of the lower layer of the coated tools 1 to 13 of the present invention and the comparative coated tools 1 to 13 is 10 μm in a direction parallel to the tool base using a scanning electron microscope (5000 times magnification). The maximum grain width W and the maximum grain length L are measured for each TiCN crystal grain existing in the region of the height of the TiCN layer in the direction perpendicular to the substrate, and the value of the aspect ratio L / W is set. The area ratio of crystal grains having an aspect ratio L / W of 5 or more in the longitudinal section of the TiCN layer was determined.
Tables 6 and 7 show the area ratios obtained above.

Further, the thicknesses of the constituent layers of the hard coating layers of the inventive coated tools 1 to 13 and comparative example coated tools 1 to 13 were measured using a scanning electron microscope (longitudinal cross section measurement). The average layer thickness (average value of 5-point measurement) substantially the same as the thickness was shown.

Next, for the various coated tools of the coated tools 1 to 13 of the present invention and the comparative coated tools 1 to 13, the following cutting conditions were set in a state where each was fixed to the tip of the tool steel tool with a fixing jig. A cutting test was performed under A and cutting conditions B.
≪Cutting condition A≫
Work material: S45C
Cutting speed: 200 m / min,
Cutting depth: 3.0mm,
Feed: 0.4mm / rev,
Cutting time: Dry continuous high-cut cutting test of carbon steel round bar under conditions of 5 minutes.
≪Cutting condition B≫
Work material: SCM440
Cutting speed: 250 m / min,
Cutting depth: 2.0mm,
Feed: 0.3mm / rev,
Cutting time: Wet intermittent cutting test of 4 alloy steel slit materials under conditions of 5 minutes.
The flank wear width of the cutting edge in the above cutting test was measured, and the occurrence of abnormal damage such as chipping, chipping and peeling was observed with the naked eye.
Tables 8 and 9 show the test results.

From the results shown in Table 8 and Table 9, since the present invention coated tools 1 to 13 have a TiCN layer excellent in plastic deformation resistance in the lower layer, TiCN crystal grains fall off, chipping caused by this, Excellent wear resistance with no chipping or peeling.
In contrast, the comparative example coated tools 1 to 13 have a relatively short service life due to abnormal damage such as dropping, chipping, chipping and peeling of TiCN crystal grains in high load / low speed cutting. It is clear that

As described above, the coated tool of the present invention exhibits excellent cutting performance in high-load / low-speed cutting in which a high load (a large shearing force) acts on the cutting edge, but the normal conditions such as various steel and cast iron Of course, it can also be used for continuous cutting and intermittent cutting.

Claims

In a surface-coated cutting tool in which a hard coating layer is formed on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
(A) The hard coating layer comprises at least a lower layer and an upper layer,
(B) The lower layer is composed of one layer or two or more layers selected from a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride oxide layer, and at least one of them is A Ti compound layer composed of Ti carbonitride layers and having a total average layer thickness of 2 to 15 μm,
(C) the upper layer comprises an aluminum oxide layer having an average layer thickness of 1 to 15 μm;
(D) In at least one Ti carbonitride layer in the Ti compound layer of the lower layer, the maximum diffraction peak intensity by X-ray diffraction appears on the (200) plane, and the orientation index Tc (200) is A surface-coated cutting tool characterized by being 2.0 or more.
2. The surface-coated cutting tool according to claim 1, wherein in the longitudinal section of the Ti compound layer, an area ratio occupied by a crystal grain having a columnar longitudinal structure having an aspect ratio of 5 or more is 70 area% or more. .
3. The surface-coated cutting tool according to claim 1, wherein in the Ti compound layer, the thickness of all Ti carbonitride layers is 1.5 to 12 μm.