JP2019005855A - Surface-coated cutting tool having hard coating layer excellent in chipping resistance - Google Patents

Abstract

To provide a surface-coated cutting tool having excellent chipping resistance for a long period even after application thereof to a high-speed high-feeding intermittent cutting work for an alloy steel and the like.SOLUTION: In a surface-coated cutting tool in which a hard coating layer is provided to a tool substrate, the hard coating layer has a laminated structure of layers A and B which are different from each other in orientation of the NaCl type face-centered cubic structure having an average layer thickness of 1 to 20 μm and are (TiAl)(CN) and (TiAl)(CN), respectively (here, 0.60≤x, s≤0.95, 0≤y and t≤0.005). When measuring the angles of inclination made by the normal lines on the {100} plane and {111} plane of the layers A and B, respectively and partitioning the angle of inclination in a range of 0-45 degrees to the normal line every 0.25 degree pitch to compile the frequencies existing in respective partitions and to obtain an inclination angle frequency distribution, a maximum peak exists in an inclination angle section within a range of 0-12 degrees. The sum of the frequencies existing in the above range indicates a ratio of 40% or more of the whole frequency in the above inclination frequency distribution.SELECTED DRAWING: Figure 1

Description

  The present invention is a high-speed, high-feed, intermittent cutting process involving high heat generation of alloy steel and the like, and a shocking load acting on the cutting edge, and the hard coating layer has excellent chipping resistance. The present invention relates to a surface-coated cutting tool (hereinafter sometimes referred to as a coated tool) that exhibits excellent cutting performance over use.

Conventionally, generally composed of tungsten carbide (hereinafter referred to as WC) based cemented carbide, titanium carbonitride (hereinafter referred to as TiCN) based cermet or cubic boron nitride (hereinafter referred to as cBN) based ultra high pressure sintered body There is a coated tool in which a Ti-Al based composite nitride layer is formed by physical vapor deposition on the surface of a tool substrate (hereinafter collectively referred to as a tool substrate) as a hard coating layer. It is known to exhibit excellent wear resistance.
However, the above-mentioned coated tool formed by coating the conventional Ti—Al based composite nitride layer is relatively excellent in wear resistance, but is likely to cause abnormal wear such as chipping when used under high-speed intermittent cutting conditions. Therefore, various proposals for improving the hard coating layer have been made.

For example, Patent Document 1 has a NaCl-type face-centered cubic structure on the surface of a tool base and is represented by a composition formula: (Ti _1-X Al _X ) (C _Y N _1-Y ) (provided that the atomic ratio is The average composition X _{avg of} Al is 0.60 ≦ X _avg ≦ 0.95, the average composition Y _{avg of} C is 0 ≦ Y _avg ≦ 0.005) and a hard coating layer including at least a TiAlCN layer is formed, For the TiAlCN layer, using an electron beam backscattering diffractometer, the inclination angle number distribution was determined by measuring the inclination angle formed by the normal of the {111} face of the TiAlCN crystal grain with respect to the normal direction of the tool base surface, The highest peak is present in the inclination angle section within the range of 0 to 12 degrees, and the sum of the frequencies existing within the range of 0 to 12 degrees is 45% or more of the entire frequencies in the inclination angle frequency distribution, Furthermore, the in-plane perpendicular to the thickness direction of the TiAlCN layer A structure having a triangular shape and a facet formed by an equivalent crystal plane represented by {111} of the crystal grains occupies an area ratio of 35% or more of the whole in a plane perpendicular to the layer thickness direction. A coating tool with improved chipping resistance of a hard coating layer in high-speed interrupted cutting and the like that is accompanied by high heat generation such as stainless steel and an impact load on the cutting edge has been proposed. .

Further, in Patent Document 2, as in Patent Document 1, high heat generation of stainless steel or the like is accompanied, and chipping resistance of the hard coating layer in high-speed intermittent cutting processing in which an impact load is applied to the cutting blade. In order to enhance the property, the surface of the tool base is represented by the composition formula: (Ti _1-X Al _X ) (C _Y N _1-Y ) (provided that the average composition X _{avg of} Al is 0. 60 ≦ X _avg ≦ 0.95, the average composition Y _{avg of} C is 0 ≦ Y _avg ≦ 0.005), and a hard coating layer including at least a TiAlCN layer having a NaCl-type face-centered cubic structure is formed, When the TiAlCN layer was measured for the tilt angle number distribution by measuring the tilt angle formed by the normal of the {100} plane of the TiAlCN crystal grain with respect to the normal direction of the tool base surface using an electron beam backscatter diffraction device , Tilt angle in the range of 0-12 degrees The sum of the frequencies having the highest peak in the minute and within the range of 0 to 12 degrees is 45% or more of the entire frequencies in the tilt angle distribution, and is perpendicular to the thickness direction of the TiAlCN layer. A polygonal facet that does not have an angle of less than 90 degrees in a plane, and the facet is formed on one of the equivalent crystal planes represented by {100} of the crystal grain, A coated tool having a structure that occupies an area ratio of 50% or more of the entire surface in a plane perpendicular to the layer thickness direction has been proposed.
Further, when XRD analysis is performed on the TiAlCN layer in the coated tool, Ic {200 between the peak intensity Ic {200} derived from the cubic structure and the peak intensity Ih {200} derived from the hexagonal structure. } / Ih {200} ≧ 3.0 holds true, the effect of improving wear resistance is further enhanced.

Further, in Patent Document 3, in order to improve the wear resistance of a tool, a 3 to 25 μm wear-resistant coating layer formed by CVD is formed on a tool substrate, and the coating layer includes at least Ti _1-1. when expressed in _x Al _x C _y N _z, the thickness of 1.5~17μm that satisfies 0.70 ≦ x <1,0 ≦ y < 0.25 and 0.75 ≦ z <1, 15 The TiAlCN layer has a lamellar structure with a lamellar spacing of less than 150 nm, the same crystal structure, and Ti _1-x Al _x C _y N _z with Ti and Al having different stoichiometry. manner is composed of alternately arranged _{Ti 1-x Al x C y} N z, _{further, Ti 1-x Al x C} y N z layer is at least 90 vol% or more is face-centered cubic structure, said layer TC value satisfies TC (111)> 1.5, { Half value width of the X-ray diffraction peak intensity of 11} plane coated tool have been proposed less than 1 degree.

Japanese Patent Laying-Open No. 2015-163423 Japanese Patent Laying-Open No. 2015-163424 International Publication No. 2015/135802

In recent years, there has been a strong demand for energy saving and energy saving in cutting, and along with this, cutting tends to be faster and more efficient, and the coated tools are even more resistant to abnormal damage such as chipping resistance. In addition to demanding properties, there is a need for a long life that can be used for a long time.
However, the coated tools proposed in Patent Documents 1 to 3 are accompanied by high heat generation of alloy steel and the like, and in high-speed high-feed intermittent cutting where an impact load is applied to the cutting edge, chipping resistance However, it is not sufficient, and it cannot be said that satisfactory cutting performance is provided over a long period of use.

  Accordingly, the present invention has been made to solve the above-mentioned problems and to provide a coated tool that exhibits excellent chipping resistance over a long period of use even when subjected to high-speed, high-feed intermittent cutting such as alloy steel. And

The present inventors have disclosed a composite nitride or composite carbonitride (hereinafter referred to as “TiAlCN” or “(Ti _1-x Al _x ) (C _y N _1-y )”) layer of Ti and Al. As a result of intensive studies to improve the chipping resistance of a coated tool provided with a hard coating layer containing at least a hard coating layer on the surface of the tool base, the following findings were obtained.

  That is, a hard coating layer in which one or more TiAlCN layers having a high orientation ratio in the normal direction of the {100} plane and one or more TiAlCN layers having a high orientation ratio in the normal direction of the {111} plane are alternately laminated, It has been found that the chipping resistance is improved even when the number of stacked layers is an odd number.

The present invention has been made based on the above findings,
“(1) In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base composed of any of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultrahigh-pressure sintered body ,
(A) The hard coating layer includes at least a composite nitride or composite carbonitride layer of Ti and A1 having an average layer thickness of 1.0 to 20.0 μm,
(B) The composite nitride or composite carbonitride layer has a laminated structure composed of two layers having different orientations, and Ti and A1 composite nitride or composite carbonitride layer A forming the laminated structure. In the case of layer and B layer,
The layer thicknesses of the A layer and the B layer are 0.5 μm or more, and the respective composition formulas are (Ti _1-x Al _x ) (C _y N _1-y ), (Ti _1-s Al _s ) (C _t N _1-t ), the content ratios x and s in the total amount of Ti and Al in the A layer and the B layer, and the content ratios y and t in the total amount of C and N in C (however, , X, s, y, and t are all atomic ratios) are 0.60 ≦ x ≦ 0.95, 0.60 ≦ s ≦ 0.95, 0 ≦ y ≦ 0.005, and 0 ≦ t, respectively. ≦ 0.005 is satisfied,
(C) The crystal orientation of the crystal grains of the composite nitride or composite carbonitride of Ti and A1 having the NaCl-type face-centered cubic structure in the A layer is determined by using the electron beam backscatter diffractometer. When analyzing from the above, the inclination angle formed by the normal line of the {100} plane, which is the crystal plane of the crystal grain, with respect to the normal direction of the tool base surface is measured. When the inclination angle within the range of degrees is divided into pitches of 0.25 degrees and the frequencies existing in each division are totaled to obtain the inclination angle number distribution, the inclination angle classification within the range of 0 to 12 degrees The sum of the frequencies existing in the range of 0 to 12 degrees indicates a ratio of 40% or more of the entire frequencies in the tilt angle frequency distribution,
(D) The crystal orientation of the composite nitride or composite carbonitride crystal grain of Ti and A1 having the NaCl-type face-centered cubic structure in the B layer is measured in the longitudinal section direction using an electron beam backscattering diffractometer. When analyzing from the above, the inclination angle formed by the normal line of the {111} plane, which is the crystal plane of the crystal grain, with respect to the normal direction of the tool base surface is measured. When the inclination angle within the range of degrees is divided into pitches of 0.25 degrees and the frequencies existing in each division are totaled to obtain the inclination angle number distribution, the inclination angle classification within the range of 0 to 12 degrees The surface-coated cutting tool is characterized in that the highest peak is present and the sum of the frequencies within the range of 0 to 12 degrees represents a ratio of 40% or more of the total frequencies in the tilt angle frequency distribution.
(2) There is a periodic concentration change of Ti and Al in at least one of the crystal grains of the A layer and the B layer, and the maximum value in which the content ratio of A1 expressed by an atomic ratio changes periodically. The surface coating according to (1), characterized in that the difference between the average value and the average minimum value is 0.03 to 0.25, and the period of change in the Al content is 3 to 100 nm. Cutting tools.
(3) The absolute value | x−s | of the difference between the average Al content ratio x of the A layer and the average Al content ratio s of the B layer is 0.10 or less (1) or ( The surface-coated cutting tool according to 2).
(4) It consists of one layer or two or more layers of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer between the tool base and the hard coating layer, And the lower layer containing the Ti compound layer which has a total average layer thickness of 0.1-20.0 micrometers exists, The surface-coated cutting tool in any one of (1)-(3) characterized by the above-mentioned.
(5) In any one of (1) to (4), an upper layer including an aluminum oxide layer having an average layer thickness of at least 1.0 to 25.0 μm exists above the hard coating layer. The surface-coated cutting tool described. "
It is.

The coated tool of the present invention comprises a TiAlCN layer (A layer) having a different orientation ratio in the normal direction of the {100} plane and a TiAlCN layer (B) having a higher orientation ratio in the normal direction of the {111} plane. Layer) are alternately laminated one by one, so that even if the number of layers is an odd number, the wear resistance and chipping resistance are greatly improved. Thus, even if it is a high-speed, high-feed, intermittent cutting process, there is a remarkable effect of exhibiting excellent cutting performance over a long period of time.
The reason for this effect is the synergy between the high hardness of the A layer having high orientation in the normal direction of the {100} plane and the high toughness of the B layer having a high orientation ratio in the normal direction of the {111} plane. Is estimated to be brought by.

It is a cross-sectional schematic diagram of the coated tool of this invention. The inclination angle formed by the normal of the {100} plane, which is the crystal plane of the crystal grain, with respect to the normal direction of the surface of the tool base in the layer A measured with the inventive coated tool 8 produced in Example 1, The number of inclination angles obtained by dividing the inclination angles in the range of 0 to 45 degrees with respect to the normal direction among the inclination angles for each pitch of 0.25 degrees and totaling the frequencies existing in each division An example of distribution is shown. The inclination angle formed by the normal of the {111} plane, which is the crystal plane of the crystal grain, with respect to the normal direction of the surface of the tool base in the B layer measured with the inventive coated tool 8 produced in Example 1, The number of inclination angles obtained by dividing the inclination angles in the range of 0 to 45 degrees with respect to the normal direction among the inclination angles for each pitch of 0.25 degrees and totaling the frequencies existing in each division An example of distribution is shown.

  Next, the hard coating layer of the coated tool of the present invention will be described in more detail.

1. The thickness of each layer of A and B constituting the hard coating layer and the average thickness of the sum of both layers:
The thickness of each layer A and B constituting the hard coating layer is 0.5 μm or more. The reason is that if the thickness is less than 0.5 μm, the characteristics of each layer may not be sufficiently exhibited even in a laminated structure. On the other hand, the upper limit of the thickness of each layer is not particularly limited, but is limited by the average layer thickness of the sum of both layers described later. That is, since each layer needs to be laminated one or more layers, 19.5 (= 20−0.5) μm is the practical upper limit.
The average layer thickness of the sum of both layers is 1 to 20 μm. The lower limit value of 1 μm corresponds to the sum of 0.5 μm (1 = 0.5 + 0.5) which is the lower limit value of the sum of the thicknesses of the respective layers. On the other hand, if the upper limit value of 20 μm exceeds 20 μm, it is difficult to ensure the sharpness of the cutting edge as a coated tool, obtain processing accuracy, prevent burrs, and ensure the quality of the processed surface.

  Here, the thickness of each layer and the average layer thickness of both layers are determined by polishing a cross section (longitudinal cross section) in a direction perpendicular to the tool base, and using the scanning electron microscope to obtain an appropriate magnification (for example, , Magnification 5000 times), and can be obtained by measuring and averaging the five layer thicknesses within the observation field.

2. Average composition of TiAlCN layers in each layer:
The TiAlCN layer in the present invention is
Containing a percentage of A layer _{(Ti 1-x Al x)} (C y N 1-y), B layer _{(Ti 1-s} Al _s) total amount of (C _{t N 1-t)} with Al Ti and Al (Hereinafter referred to as “average content ratio of Al”) x, s,
The average content ratio (hereinafter referred to as “the average content ratio of C”) y and t in the total amount of C and N of C are:
0.60 ≦ x ≦ 0.95, 0.60 ≦ s ≦ 0.95, 0 ≦ y ≦ 0.005, 0 ≦ t ≦ 0.005 (where x, s, y, and t are all (Atomic ratio).
The reason is that when the average Al content ratio x, s is less than 0.60, the TiAlCN layer is inferior in hardness, so when subjected to high-speed high-feed intermittent cutting, the wear resistance is not sufficient, Further, when the average Al content ratio x, s exceeds 0.95, the Ti content ratio is relatively decreased, leading to embrittlement and lowering of chipping resistance.
Therefore, the average Al content ratio x and the s average content ratio were determined as 0.60 ≦ x ≦ 0.95 and 0.60 ≦ s ≦ 0.95.
In addition, when the average content ratios y and t of C contained in the TiAlCN layer are in the range of 0 ≦ y ≦ 0.005 and 0 ≦ t ≦ 0.005, the adhesion between the TiAlCN layer and the tool substrate or the lower layer As a result, the impact at the time of cutting is reduced by improving the lubricity, and as a result, the chipping resistance of the TiAlCN layer is improved. On the other hand, if the average content ratio z of C deviates from the range of 0 ≦ y ≦ 0.005 and 0 ≦ t ≦ 0.005, the toughness of the TiAlCN layer is lowered and the chipping resistance is lowered, which is not preferable.
Accordingly, the average content ratios s and t of C are determined as 0 ≦ y ≦ 0.005 and 0 ≦ t ≦ 0.005.

Here, the average content ratios x and s of Al in the TiAlCN layer are obtained by irradiating an electron beam from the vertical cross section side in a sample obtained by polishing a sample cross section using Auger Electron Spectroscopy (AES). The average content x and s of Al can be obtained from the average of each layer using five of the analysis results of Auger electrons obtained by performing line analysis in the direction.
The average C content y and t can be determined by secondary ion mass spectrometry (Secondary-Ion-Mass- Spectroscopy: SIMS). The ion beam was irradiated in the range of 70 μm × 70 μm from the longitudinal section side, and the concentration in the depth direction was measured for the components emitted by the sputtering action. Average content ratios y and t of C indicate average values in the depth direction of the TiAlCN layer.
However, the content ratio of C excludes an unavoidable content ratio of C that is included even if a gas containing C is not intentionally used as a gas raw material.

3. When the crystal orientation of the crystal grains of the composite nitride or composite carbonitride of Ti and A1 in the A layer and the B layer is analyzed from the longitudinal sectional direction using an electron beam backscattering diffractometer, the method of the tool base surface The inclination angle formed by the normal line of the {100} plane (A layer) or the normal line of the {111} plane (B layer), which is the crystal plane of the crystal grain with respect to the line direction, is measured, On the other hand, when the inclination angle in the range of 0 to 45 degrees is divided into pitches of 0.25 degrees and the frequencies existing in each division are totaled to obtain the inclination angle number distribution, the range of 0 to 12 degrees is obtained. And the sum of the frequencies existing in the range of 0 to 12 degrees is 40% or more of the entire frequencies in the tilt angle frequency distribution:
When each of the A layer and the B layer has this predetermined inclination angle number distribution, both layers have a laminated structure, thereby exhibiting excellent wear resistance and chipping resistance even in high-speed high-feed intermittent cutting. In addition, the progress of cracks is suppressed, and the fracture resistance is greatly improved.
This is because the hardness is given by the high orientation ratio in the normal direction of the {100} plane of the A layer, and the hardness is maintained by the high orientation ratio in the normal direction of the {111} plane of the B layer. It is presumed that toughness is given.
Here, when analyzing the crystal orientation of each crystal grain using an electron beam backscattering diffractometer, the crystal plane whose inclination angle with respect to the normal of the substrate surface is greater than 12 degrees is the normal direction of the {100} plane, Alternatively, it cannot be regarded as oriented in the normal direction of the {111} plane, the orientation in the normal direction of the {100} plane, or the normal direction of the {111} plane is strong, and the hardness or Since the range in which the toughness does not decrease is from 0 to 12 degrees, the range of the inclination angle section for obtaining the frequency by measurement was set to 0 to 12 degrees.

Here, the inclination angle number distribution of the A layer and the B layer was obtained as follows.
First, field-emission scanning electrons with a cross section (longitudinal section) perpendicular to the tool base surface of a hard coating layer including a composite nitride layer or composite carbonitride layer of cubic structure Ti and Al as a polished surface It was set in the lens barrel of the microscope. On the polishing surface (cross-section polishing surface), the measurement range is a sufficient length range with respect to the film thickness in the direction perpendicular to the tool substrate surface and a length of 100 μm in the horizontal direction with respect to the tool substrate surface. An electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees on the polished surface and an irradiation current of 1 nA, each crystal grain having a cubic crystal lattice existing within the measurement range of the cross-sectional polished surface is 0.01 μm / step. Based on the electron beam backscatter diffraction image obtained by irradiation at intervals, the A layer is the crystal plane of the crystal grain with respect to the normal of the substrate surface (direction perpendicular to the substrate surface in the cross-section polished surface) The inclination angle formed by the normal line of the {100} plane and the inclination angle formed by the normal line of the {111} plane, which is the crystal plane of the crystal grain, for the B layer for each measurement point (point irradiated with the electron beam) Each was measured. And based on this measurement result, among the measured inclination angles, the inclination angles within the range of 0 to 45 degrees are divided into pitches of 0.25 degrees, and the frequencies existing in each division are tabulated. By doing so, the inclination angle number distribution was obtained. From the obtained inclination angle frequency distribution, the presence or absence of the highest peak of the frequency existing in the range of 0 to 12 degrees is confirmed, and the frequency existing in the range of 0 to 45 degrees (the entire frequency in the inclination angle frequency distribution) The ratio of the frequency existing in the range of 0 to 12 degrees with respect to was determined. In the inclination angle distribution graph, the total number of frequencies existing in the range of 0 to 12 degrees is more preferably 50% or more of the entire frequencies in the inclination angle frequency distribution.

4). The difference between the average value of the maximum value and the average value of the minimum value of the Al content ratio and the period of change in the Al content ratio:
In at least some of the crystal grains having a cubic structure constituting the hard coating layer, there may be a portion where a change in the periodic content ratio of Ti and Al is present at least partially in the crystal growth direction. In this part, as a change in the periodic content ratio, the difference between the average value of the maximum value and the average value of the minimum value of the Al content ratio expressed in atomic ratio is 0.03 to 0.25, and this Al content It is desirable that the ratio change period is 3 to 100 nm. If the Al content ratio change and period are in this range, it is possible to further expect a sufficient improvement in hardness and fracture resistance.

The presence or absence of periodic change in the Al content ratio, the difference between the maximum value and the minimum value of the periodic change, and the period width are the composite nitride layer or composite carbonitride using a transmission electron microscope (magnification 200000 times) It confirmed by observation of the micro area | region of a layer. For example, using an energy dispersive X-ray spectroscopy (EDS), a surface analysis is performed on a 400 nm × 400 nm region in a cross section (longitudinal cross section) perpendicular to the tool base surface, and the color density of the cubic crystal grains is striped. In the cubic crystal grains, there is a periodic composition change of Ti and Al in TiAlCN. For the crystal grains in which such a change in density is observed, the magnification is set so that the composition change of about 10 cycles from the density is within the measurement range based on the result of the surface analysis, and then the method of the tool base surface is set. A line analysis by EDS is performed in the range of 5 cycles along the line direction, and the difference between the average value of the maximum value and the minimum value of the periodic change in the Al content ratio is obtained. The average interval between them was determined as the period of periodic composition change of Ti and Al.

5. Absolute value of difference in average Al content ratio between A layer and B layer | xs |:
The absolute value | x−s | of the difference between the average Al content ratio of the A layer and the average Al content ratio of the B layer is preferably 0.1 or less. This is because if it is less than this value, the adhesion strength at the interface between the A layer and the B layer is improved, and a further improvement in chipping resistance can be expected.

6). Deposition method (conditions)
The TiAlCN layer of the present invention is, for example, for forming an A layer and a B layer on at least one of a tool substrate or a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer. It can be obtained by supplying a gas having the above reaction gas composition under predetermined conditions and forming a film.
For example,% representing gas composition is volume%,
A layer (oriented in the normal direction of {100} plane)
Gas group A
_{NH 3: 2.0~3.0%, H 2} : 65~75%
Gas group B
AlCl ₃ : 0.6 to 0.9%, TiCl ₄ : 0.2 to 0.3%, Al (CH ₃ ) ₃ : 0.0 to 0.5%, N ₂ : 0.0 to 12.0 %, H ₂ : residual reaction atmosphere pressure: 4.5 to 5.0 kPa
Reaction atmosphere temperature: 700-900 ° C
Supply cycle: 0 to 7 seconds Gas supply time per cycle: 0.00 to 0.35 seconds Phase difference in supply of gas group A and gas group B: 0.00 to 0.30 seconds B layer ({111} Oriented in the normal direction of the surface)
Gas group A
_{NH 3: 1.0~1.5%, N 2} : 0.0~5.0%, H 2: 55~60%
Gas group B
AlCl ₃ : 0.6 to 0.9%, TiCl ₄ : 0.2 to 0.3%, A1 (CH ₃ ) ₃ : 0.0 to 0.5%, N ₂ : 0.0 to 12.0 %, H ₂ : residual reaction atmosphere pressure: 4.5 to 5.0 kPa
Reaction atmosphere temperature: 700-900 ° C
Supply cycle: 0 to 7 seconds Gas supply time per cycle: 0.00 to 0.35 seconds,
Phase difference of supply of gas group A and gas group B: 0.00 to 0.30 seconds can be raised.
Note that the phase difference between the supply cycle, the gas supply time per cycle, and the supply of the gas group A and the gas group B is 0 second, indicating that the gases of the gas group A and the gas group B are supplied without being separated. Means that

Next, examples will be described.
Here, as a specific example of the coated tool of the present invention, a tool base applied to an insert cutting tool using a WC-based ultrahigh-pressure sintered body will be described. As a tool base, TiCN-based cermet, cBN-based ultrahigh-pressure sintered The same applies to the case where the body is used, and the same applies when applied to a drill or an end mill.

As raw material powders, WC powder, TiC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared, and these raw material powders are blended as shown in Table 1. Blended into the composition, added with wax, mixed in a ball mill in acetone for 24 hours, dried under reduced pressure, pressed into a compact of a predetermined shape at a pressure of 98 MPa, and the compact was 1370 in a vacuum of 5 Pa. Vacuum sintered at a predetermined temperature within a range of ˜1470 ° C. for 1 hour, and after sintering, tool bases A to C made of WC-base cemented carbide with ISO standard SDKN1504AETN insert shape are manufactured. did.

Next, a TiAlCN layer was formed on the surfaces of the tool bases A to C by using a CVD apparatus, and the inventive coated tools 1 to 10 shown in Table 6 were obtained.
The film formation conditions are as described in Tables 2 and 3, and are generally as follows.
A layer (oriented in the normal direction of {100} plane)
Gas group A
_{NH 3: 2.0~3.0%, H 2} : 65~75%
Gas group B
AlCl ₃ : 0.6 to 0.9%, TiCl ₄ : 0.2 to 0.3%, Al (CH ₃ ) ₃ : 0.0 to 0.5%, N ₂ : 0.0 to 12.0 %, H ₂ : residual reaction atmosphere pressure: 4.5 to 5.0 kPa
Reaction atmosphere temperature: 700-900 ° C
Supply cycle: 0 to 7 seconds Gas supply time per cycle: 0.00 to 0.35 seconds Phase difference in supply of gas group A and gas group B: 0.00 to 0.30 seconds B layer ({111} Oriented in the normal direction of the surface)
Gas group A
_{NH 3: 1.0~1.5%, N 2} : 0.0~5.0%, H 2: 55~60%
Gas group B
AlCl ₃ : 0.6 to 0.9%, TiCl ₄ : 0.2 to 0.3%, A1 (CH ₃ ) ₃ : 0.0 to 0.5%, N ₂ : 0.0 to 12.0 %, H ₂ : residual reaction atmosphere pressure: 4.5 to 5.0 kPa
Reaction atmosphere temperature: 700-900 ° C
Supply cycle: 0 to 7 seconds Gas supply time per cycle: 0.00 to 0.35 seconds,
Phase difference in supply of gas group A and gas group B: 0.00 to 0.30 sec. Note that 4 to 9 of the present coated tool are shown in Table 5 according to the film forming conditions described in Table 4. A lower layer and / or an upper layer were formed.

For comparison purposes, a hard coating layer including a TiAlCN layer shown in Table 6 is formed by vapor deposition on the surfaces of the tool bases A to C according to the conditions shown in Tables 2 and 3 for comparative coating. Tools 1-10 were manufactured. For comparison, the formation conditions E ′ and F ′ were vapor-deposited with a single layer of layer A or layer B without a laminated structure.
In addition, about the comparison coating tools 4-9, the lower layer and / or the upper layer which were shown in Table 5 were formed by the formation conditions shown in Table 4.

Moreover, about the hard coating layers of the present invention coated tools 1 to 10 and comparative coated tools 1 to 10, the average Al content ratios x and s of the A layer and the B layer and the average C content ratio y and t was calculated. Further, the inclination angles formed by the normal of the {100} plane for the A layer and the normal of the {111} plane for the B layer with respect to the normal of the substrate surface in the A layer and B layer obtained by the above-described method In the number distribution, it was confirmed whether or not the highest peak of the tilt angle number was present at 0 to 12 degrees, and the ratio of the frequency at which the tilt angle was within the range of 0 to 12 degrees was determined. In addition, the presence or absence of the period along the normal direction of the tool base surface of the Ti and Al composition change, the difference between the average of the maximum value and the average of the minimum value of the Al content ratio, and the period width thereof are the same as described above. It measured by the method of. In addition, the measurement of the period-related items is performed by measuring the presence or absence of periodicity in order from the tool base layer to the cutting edge side layer, and the layer first found to have periodicity, that is, the most base side. The difference between the layer period and the average of the maximum and minimum values of the Al content was determined. These results are summarized in Table 6.

Subsequently, with respect to the coated tool of the present invention and the comparative coated tool, a dry high-speed high-feed front milling machine of alloy steel as shown below in a state where both are clamped to a tool steel cutter tip having a cutter diameter of 125 mm by a fixing jig. Then, a center cut cutting test was performed, and the flank wear width of the cutting edge was measured.
Cutting test: dry high-speed face milling, center-cut cutting work material: JIS / SCM430 block material with a width of 100 mm and a length of 400 mm Rotating speed: 764 min ⁻¹
Cutting speed: 300 m / min
Cutting depth: 2.5mm
Single blade feed: 3.0 mm / blade cutting time: 8 minutes (normal cutting speed is 150 to 200 m / min, normal single blade feed: 1.0 to 2.0 mm / blade)
Table 7 shows the results of the cutting test. In addition, about the comparison coated tools 1-10, since it reached the lifetime due to chipping generation | occurrence | production, the time until it reaches a lifetime is shown.

As raw material powders, WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder and Co powder all having an average particle diameter of 1 to 3 μm are prepared. It mix | blended with the compounding composition shown by Table 8, and also added the wax, ball mill mixed in acetone for 24 hours, and dried under reduced pressure. Then, it was press-molded into a green compact having a predetermined shape at a pressure of 98 MPa, and this green compact was vacuum sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour. After sintering, the tool bases α to γ made of WC-base cemented carbide having the insert shape of ISO standard CNMG120212 were manufactured by performing honing of R: 0.07 mm on the cutting edge part.

Next, a TiAlCN layer is formed on the surfaces of these tool bases α to γ using the CVD apparatus under the conditions shown in Tables 2 and 3 in the same manner as in Example 1, and shown in Table 10. The present invention coated tools 11 to 20 were obtained.
In addition, 14-19 of this invention coated tool formed the lower layer and / or the upper layer which were shown in Table 9 by the film-forming conditions described in Table 4.

Similarly to Example 1, for the purpose of comparison, the hard coating containing the TiAlCN layer shown in Table 10 is used on the surface of the tool base α to γ by using the CVD method under the conditions shown in Tables 2 and 3. Comparative coating tools 11-20 were produced by vapor deposition of layers.
In addition, about the comparison coating tools 14-19, the lower layer and / or the upper layer which were shown in Table 9 were formed by the formation conditions shown in Table 4.

Moreover, similarly to Example 1, about the hard coating layer of the said invention coated tool 11-20 and the comparative coating tool 11-20, the average Al content rate x of a A layer and a B layer, s, and the average C content rate y, t is calculated, and the frequency of the inclination angle formed by the normal of the {100} plane and the normal of the {111} plane with respect to the normal of the substrate surface in the A layer and the B layer obtained by the above-described method, respectively. In the distribution, it is confirmed whether the highest peak of the inclination angle exists in the range of 0 to 12 degrees, the ratio of the frequency in which the inclination angle is in the range of 0 to 12 degrees, and the tool base of the composition change of Ti and Al The presence or absence of a period along the normal direction of the surface, the difference between the average of the maximum value and the average of the minimum value of the Al content ratio, and the period width thereof were measured. These results are summarized in Table 10.

Next, in the state where each of the various coated tools is screwed to the tip of the tool steel tool with a fixing jig, the present coated tools 11 to 20 and comparative coated tools 11 to 20 are shown below. A dry high-speed intermittent cutting test (cutting condition 1) of carbon steel and a wet high-speed intermittent cutting test (cutting condition 2) of cast iron were carried out, and both measured the flank wear width of the cutting edge. The results are shown in Table 11. In addition, about the comparison coated tools 11-20, since it reached the lifetime due to chipping generation | occurrence | production, the time until it reaches a lifetime is shown.

Cutting condition 1:
Work material: JIS · S15C lengthwise equal length 4 vertical grooved round bar Cutting speed: 320m / min
Cutting depth: 2.5mm
Single-blade feed rate: 0.4 mm / blade Cutting time: 5 minutes (normal cutting speed is 220 m / min, normal single-blade feed rate: 0.25 mm / blade)

Cutting condition 2:
Work material: JIS / FCD450 in the longitudinal direction, four equally spaced round bars with a vertical groove Cutting speed: 300 m / min
Cutting depth: 2.5mm
Single blade feed rate: 0.4 mm / tooth Cutting time: 5 minutes (normal cutting speed is 250 m / min, normal single blade feed rate: 0.25 mm / tooth)

  From the results shown in Tables 7 and 11, the coated tools 1 to 20 of the present invention were used for high-speed high-feed cutting such as alloy steel because the hard coating layer has excellent chipping resistance. In this case, chipping does not occur and excellent wear resistance is exhibited over a long period of time. On the other hand, comparative coated tools 1 to 20 that do not satisfy even one of the matters defined in the coated tool of the present invention are used for high-speed high-feed intermittent cutting of alloy steel and the like, and chipping is performed. Has occurred and has reached the end of its service life in a short time.

  As described above, the coated tool of the present invention can be used as a coated tool for high-speed, high-feed, intermittent cutting other than alloy steel, and exhibits excellent wear resistance over a long period of time. It is possible to satisfactorily satisfy the demands for energy saving and cutting, energy saving, and cost reduction.

Claims (5)

In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base composed of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultrahigh-pressure sintered body,
(A) The hard coating layer includes at least a composite nitride or composite carbonitride layer of Ti and A1 having an average layer thickness of 1.0 to 20.0 μm,
(B) The composite nitride or composite carbonitride layer has a laminated structure composed of two layers having different orientations, and Ti and A1 composite nitride or composite carbonitride layer A forming the laminated structure. In the case of layer and B layer,
The layer thicknesses of the A layer and the B layer are 0.5 μm or more, and the respective composition formulas are (Ti _1-x Al _x ) (C _y N _1-y ), (Ti _1-s Al _s ) (C _t N _1-t ), the content ratios x and s in the total amount of Ti and Al in the A layer and the B layer, and the content ratios y and t in the total amount of C and N in C (however, , X, s, y, and t are all atomic ratios) are 0.60 ≦ x ≦ 0.95, 0.60 ≦ s ≦ 0.95, 0 ≦ y ≦ 0.005, and 0 ≦ t, respectively. ≦ 0.005 is satisfied,
(C) The crystal orientation of the crystal grains of the composite nitride or composite carbonitride of Ti and A1 having the NaCl-type face-centered cubic structure in the A layer is determined by using the electron beam backscatter diffractometer. When analyzing from the above, the inclination angle formed by the normal line of the {100} plane, which is the crystal plane of the crystal grain, with respect to the normal direction of the tool base surface is measured. When the inclination angle within the range of degrees is divided into pitches of 0.25 degrees and the frequencies existing in each division are totaled to obtain the inclination angle number distribution, the inclination angle classification within the range of 0 to 12 degrees The sum of the frequencies existing in the range of 0 to 12 degrees indicates a ratio of 40% or more of the entire frequencies in the tilt angle frequency distribution,
(D) The crystal orientation of the composite nitride or composite carbonitride crystal grain of Ti and A1 having the NaCl-type face-centered cubic structure in the B layer is measured in the longitudinal section direction using an electron beam backscattering diffractometer. When analyzing from the above, the inclination angle formed by the normal line of the {111} plane, which is the crystal plane of the crystal grain, with respect to the normal direction of the tool base surface is measured. When the inclination angle within the range of degrees is divided into pitches of 0.25 degrees and the frequencies existing in each division are totaled to obtain the inclination angle number distribution, the inclination angle classification within the range of 0 to 12 degrees The surface-coated cutting tool is characterized in that the highest peak is present and the sum of the frequencies within the range of 0 to 12 degrees represents a ratio of 40% or more of the total frequencies in the tilt angle frequency distribution. At least one of the crystal grains of the A layer and the B layer has a periodic concentration change of Ti and Al, and the average value of the maximum value of the value in which the content ratio of A1 expressed by an atomic ratio changes periodically. 2. The surface-coated cutting tool according to claim 1, wherein a difference between the average value of the minimum value and the minimum value is 0.03 to 0.25, and a period of change in the Al content ratio is 3 to 100 nm.   3. The absolute value | x−s | of the difference between the average Al content ratio x of the A layer and the average Al content ratio s of the B layer is 0.10 or less. Surface coated cutting tool. Between the tool base and the hard coating layer, one or two or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer are formed, and 0 The surface-coated cutting tool according to any one of claims 1 to 3, wherein there is a lower layer including a Ti compound layer having a total average layer thickness of 1 to 20.0 µm. 5. The surface according to claim 1, wherein an upper layer including an aluminum oxide layer having an average layer thickness of at least 1.0 to 25.0 μm is present on the hard coating layer. Coated cutting tool.