JP2007203447A - Surface-coated cermet cutting tool with hard coating layer having excellent chipping resistance in high-speed intermittent cutting work - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cermet cutting tool with a hard coating layer having an excellent chipping resistance in a high-speed intermittent cutting work. <P>SOLUTION: The surface-coated cermet cutting tool is formed on the surface of a tool substrate the hard coating layer comprising a composite nitride layer of Ti and Al which has an average layer thickness of 1-6 μm and satisfies empirical formula (Ti<SB>1-X</SB>Al<SB>X</SB>)N (wherein X is not less than 0.4 and not more than 0.6 in the atomic ratio). The composite nitride layer of Ti and Al is composed of a titanium nitride aluminum layer, which shows a specific atom sharing lattice point distribution graph obtained by using a field-emission scanning electron microscope, irradiating individual crystal particles present in a measuring range of a surface-polishing plane with electron beams, measuring a tilt angle formed by the normal lines of face (001) and face (011) as a crystal plane of the crystal particles with respect to the normal line of the surface-polishing plane, and calculating the atom sharing lattice point distribution graph from the measured tilt angle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In particular, the present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent chipping resistance in a high-speed intermittent cutting process in which a large mechanical impact is applied to the cutting edge. .

Conventionally 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 material On the surface of the substrate (hereinafter collectively referred to as a tool substrate),
Composition formula: (Ti _1-X Al _X ) N (however, in atomic ratio, X represents 0.4 to 0.6),
There is known a coated tool formed by vapor-depositing a hard coating layer composed of a composite nitride of Ti and Al [hereinafter referred to as (Ti, Al) N] satisfying the above-mentioned conditions, and the hard coating layer of the coated tool The (Ti, Al) N layer has high-temperature hardness and heat resistance due to Al as a constituent component, and high-temperature strength due to the Ti, so this is continuously cut from various general steels and ordinary cast iron, etc. It is also known to exhibit excellent cutting performance when used for intermittent cutting.
Japanese Patent No. 2644710 Japanese Patent Laid-Open No. 9-291353

  In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting work, and along with this, cutting work tends to be further accelerated. For coated tools, there is no problem when this is used for cutting under normal conditions such as steel or cast iron, but especially when this is used for high-speed intermittent cutting with severe cutting conditions, a hard coating layer is used. The (Ti, Al) N layer constituting the material cannot sufficiently respond to mechanical impact due to insufficient high-temperature strength. As a result, chipping (minute chipping) occurs in the hard coating layer. The current situation is that it becomes easier and reaches the service life in a relatively short time.

In view of the above, the present inventors, in order to improve the chipping resistance of the above-mentioned coated tool, (Ti, Al) N layer which is a hard coating layer thereof, that is, FIG. 2 (a). As shown in the schematic diagram, a crystal structure of NaCl face-centered cubic crystal in which constituent atoms composed of Ti, Al, and nitrogen are present at lattice points (FIG. 2 (b) is a state cut along the (011) plane. As a result of conducting research by focusing on the (Ti, Al) N layer having
(A) The (Ti, Al) N layer constituting the hard coating layer of the conventional coated tool is, for example, an arc ion plating apparatus which is a kind of a normal physical vapor deposition apparatus, in which a tool base is inserted, and a heater In the state where the inside of the apparatus is heated to 500 ° C., for example, a current of 100 A is applied between the cathode electrode (evaporation source) made of a Ti—Al alloy having a predetermined composition and the anode electrode to generate arc discharge, and at the same time Nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 2 Pa, for example, while a bias voltage of, for example, −50 V is applied to the tool base (hereinafter referred to as normal film formation conditions). However, as shown in FIGS. 1 (a) and 1 (b), for example, electromagnetic coils 1 to 6 are installed in a total of 6 locations on the outer periphery of the upper and lower surfaces of the furnace body and on the outer periphery of the four side surfaces. DC power supply When a magnetic field of about 400 G is generated in each electromagnetic coil, a special magnetic field state is formed in the furnace, and (Ti, Al) N according to the normal film formation conditions in such a special magnetic field. When the layers are formed by vapor deposition, the resulting (Ti, Al) N layer (hereinafter referred to as a modified (Ti, Al) N layer) is a (Ti, Al) N layer formed under normal film formation conditions. Compared to the above, the high temperature strength is further improved, and it has excellent mechanical impact resistance, so the hard coating layer has excellent chipping resistance even in high-speed intermittent cutting with severe mechanical impact. Demonstrate and show excellent wear resistance over a long period of time.

(B) The (Ti, Al) N layer (hereinafter referred to as the conventional (Ti, Al) N layer) constituting the hard coating layer of the conventional coated tool and the modified (Ti, Al) N layer of (a). about,
Using a field emission scanning electron microscope, as illustrated in the schematic explanatory diagrams in FIGS. 3A and 3B, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, The inclination angle formed by the normal lines of the (001) plane and the (011) plane, which are crystal planes of the crystal grains, with respect to the normal line of the surface polished surface (FIG. 3A shows (001) of the crystal planes). When the tilt angle of the surface is 0 degree and the tilt angle of the (011) plane is 45 degrees, the tilt angle of the (001) plane is 45 degrees and the tilt angle of the (011) plane is 0 degree. However, in this case, the crystal grains have constituent atoms composed of Ti, Al, and nitrogen at lattice points as described above, respectively. Based on the resulting measured tilt angle, which has an NaCl-type face-centered cubic crystal structure present The distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains is calculated at the interface between the constituent atomic shared lattice points. The constituent atomic shared lattice point form in which N lattice points that do not share atoms (N is an even number of 2 or more in the crystal structure of the NaCl type face-centered cubic crystal) is represented by ΣN + 1, and each ΣN + 1 is an entire ΣN + 1 (however, When the constituent atomic shared lattice point distribution graph showing the distribution ratio of the upper limit value of N in terms of frequency is 28), the highest peak exists in Σ3 in any TiAlN layer, but the conventional (Ti , Al) N layer, as illustrated in FIG. 5, shows a relatively low constituent atom shared lattice point distribution graph in which the distribution ratio of Σ3 is 30% or less, whereas the modified (Ti, Al) The N layer is illustrated in FIG. Ri, distribution ratio of Σ3 showed extremely high atom sharing lattice point distribution graph of the 50% to 80%, the distribution ratio of the high Σ3 is to vary with the furnace in the magnetic field distribution at the time of film formation by vapor deposition.

(C) In addition to the high temperature hardness and high temperature strength that the (Ti, Al) N layer itself has, the modified (Ti, Al) N layer is further improved compared to the conventional (Ti, Al) N layer. Since it has high high-temperature strength, a coated tool formed by vapor deposition as a hard coating layer is formed by depositing the conventional (Ti, Al) N layer, especially when used for intermittent cutting at high speed. Compared to the coated tool, the hard coating layer will exhibit better chipping resistance.
The research results shown in (a) to (c) above were obtained.

The present invention has been made based on the above research results, and is provided on the surface of a tool base made of a WC-based cemented carbide, a TiCN-based cermet, or a cBN-based ultrahigh pressure sintered material.
In a surface-coated cutting tool formed by vapor-depositing a hard coating layer made of a composite nitride of Ti and Al having an average layer thickness of 1 to 6 μm,
When the composition formula of the hard coating layer is expressed as (Ti _1-X Al _X ) N,
0.4 ≦ X ≦ 0.6 (where X represents an atomic ratio), and
Using a field emission scanning electron microscope, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal plane of the crystal grain is normal to the surface polished surface ( The tilt angle formed by the normal lines of the (001) plane and the (011) plane is measured. In this case, the crystal grains are NaCl-type face-centered cubic crystals each having a constituent atom composed of Ti, Al, and nitrogen at lattice points. Based on the measured tilt angle obtained as a result of this, at the interface between adjacent crystal grains, each of the constituent atoms shares one constituent atom between the crystal grains (configuration The distribution of atomic shared lattice points) is calculated, and there are N lattice points that do not share constituent atoms between the constituent atomic shared lattice points (N is an even number of 2 or more in the crystal structure of NaCl-type face-centered cubic crystal). The constitutive atomic shared lattice point form is expressed as ΣN + 1 In the constituent atom shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1 (however, the upper limit value of N is 28 in relation to the frequency), the highest peak exists in Σ3, and the Σ3 A titanium aluminum nitride layer showing a constituent atom shared lattice point distribution graph in which the distribution ratio of ΣN + 1 in the whole is 50% to 80%,
It is characterized by a coated tool (surface-coated cutting tool) that exhibits excellent chipping resistance with a hard coating layer in high-speed intermittent cutting characterized by comprising the above.

Next, the reason why the titanium aluminum nitride layer [modified (Ti, Al) N layer], which is a hard coating layer of the coated tool of the present invention, is numerically limited as described above will be described below.
(A) Composition formula (Ti _1-X Al _X ) N
In the hard coating layer having a composition represented by the composition formula (Ti _1-X Al _X ) N, the Ti component contributes to maintaining high-temperature strength, and the Al component contributes to improving high-temperature hardness and heat resistance. A layer having a predetermined high-temperature strength, high-temperature hardness, and heat resistance, but when the Al content ratio X exceeds 60 atomic%, the high-temperature hardness and heat resistance of the hard coating layer are improved, but the Ti content ratio As a result of the relative decrease in strength, the high temperature strength decreases and chipping is likely to occur. On the other hand, when the Al content ratio X is less than 40 atomic%, the high temperature hardness and heat resistance decrease, resulting in wear resistance. Since the decrease is observed, the value of the Al content ratio X is set to 0.40 to 0.60.

(B) Distribution ratio of Σ3 The distribution ratio of Σ3 in the constituent atomic shared lattice point distribution graph of the modified (Ti, Al) N layer is changed by changing the magnetic field distribution in the furnace during vapor deposition as described above. In this case, if the distribution ratio of Σ3 is less than 50%, it is possible to ensure excellent high-temperature strength improvement effect that high-speed intermittent cutting does not cause chipping in the hard coating layer. Therefore, the higher the distribution ratio of Σ3, the better. However, since it is difficult to increase the distribution ratio of Σ3 beyond 80% in terms of layer formation, the distribution ratio of Σ3 is 50% to 80%. Determined. As described above, the modified (Ti, Al) N layer has a further excellent high-temperature strength in addition to the high-temperature hardness, high-temperature strength and heat resistance of (Ti, Al) N itself as described above. .

(C) Average layer thickness When the average layer thickness of the hard coating layer is less than 1 μm, the heat resistance, high temperature hardness and high temperature strength of the hard coating layer cannot be imparted to the hard coating layer over a long period of time, resulting in a short tool life. On the other hand, if the average layer thickness exceeds 6 μm, chipping is likely to occur. Therefore, the average layer thickness was set to 1 to 6 μm.

  In order to secure sufficient adhesion between the tool base and the modified (Ti, Al) N layer, a titanium nitride (TiN) layer is interposed between the base and the modified (Ti, Al) N layer. However, if the TiN layer has a layer thickness of less than 0.01 μm, the effect of improving the adhesion is small. On the other hand, even if the layer thickness exceeds 0.5 μm, further improvement in the adhesion cannot be expected. Therefore, the thickness of the TiN layer interposed between the tool base and the modified (Ti, Al) N layer is preferably 0.01 to 0.5 μm.

  The coated tool according to the present invention has a high-temperature strength with a modified (Ti, Al) N layer, which is a hard coating layer, even in high-speed intermittent cutting such as steel and cast iron, which has a great mechanical impact on the cutting edge. Since it exhibits excellent chipping resistance, it exhibits excellent wear resistance without occurrence of chipping in the hard coating layer.

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

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders were blended into the composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact with a predetermined shape at a pressure of 98 MPa. The green compact was vacuum sintered at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa. After sintering, the cutting edge portion was R: 0.07 mm honing By performing the processing, tool bases A to F made of a WC-base cemented carbide having a throwaway tip shape specified in ISO · CNMG120408 were manufactured.

In addition, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder, all having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and 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 pressed into a compact at a pressure of 98 MPa. The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after the sintering, the cutting edge portion was subjected to a honing process of R: 0.07 mm. Tool bases G to L made of TiCN-based cermet having a standard / CNMG12041 chip shape were formed.

Furthermore, as raw material powders, cubic boron nitride (cBN) powder, titanium nitride (TiN) powder, Al powder, aluminum oxide (Al ₂ O ₃ ) powder each having an average particle diameter in the range of 0.5 to 4 μm. These raw material powders were blended in the composition shown in Table 3, wet-mixed with a ball mill for 80 hours, dried, and then had a diameter of 50 mm × thickness: 1.5 mm at a pressure of 120 MPa. The green compact is press-molded, and then the green compact is sintered in a vacuum atmosphere at a pressure of 1 Pa at a predetermined temperature within the range of 900 to 1300 ° C. for 60 minutes and pre-baked for cutting edge pieces. A WC-based cemented carbide support piece having a size of Co: 8% by mass, WC: remaining composition, and diameter: 50 mm × thickness: 2 mm was prepared as a sintered body. Super After charging into a high-pressure sintering apparatus, sintering under ultrahigh pressure at a predetermined temperature in the range of pressure: 5 GPa, temperature: 1200 to 1400 ° C., holding time: 0.8 hours, after sintering The upper and lower surfaces are polished with a diamond grindstone and divided into a regular triangle shape with a side of 3 mm by a wire electric discharge machine. Further, Co: 5 mass%, TaC: 5 mass%, WC: remaining composition and The brazing part (corner part) of the WC-based cemented carbide chip body having the shape (thickness: 4.76 mm × one side length: 12.7 mm) is mass%, Cu: 26%, Ti: 5%, Ni: 2.5%, Ag: Brazing using a brazing material of an Ag alloy having the remaining composition, and after peripheral processing to a predetermined dimension, the width of the cutting edge is 0.13 mm, Angle: 25 ° honing process, The tool substrate M~R having a tip shape of ISO standard SNGA120412 by performing finish polishing was produced, respectively.

Next, each of these tool bases A to F, G to L, and M to R is ultrasonically cleaned in acetone and dried, on the rotary table in the arc ion plating apparatus shown in FIG. Attached along the outer periphery at a position spaced apart from the central axis in the radial direction along the outer periphery, and modified as a cathode electrode (evaporation source) having a component composition corresponding to the target composition shown in Tables 5 to 7 (Ti , Al) Ti-Al alloy for N layer formation is arranged,
(B) First, while the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, the inside of the apparatus is heated to 500 ° C. with a heater, and then Ar gas is introduced to create an atmosphere of 0.7 Pa. A DC bias voltage of −200 V is applied to the tool base that rotates while rotating on the table, and the tool base surface is bombarded with argon ions.
(C) Nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 2 Pa, a DC bias voltage of −50 V is applied to the tool base that rotates while rotating on the rotary table, and the cathode electrode An arc discharge is generated by passing a current of 100 A between the (modified Ti, Al) N layer-forming Ti-Al alloy) and the anode electrode, and at the same time, as shown in FIG. ) A magnetic field shown in Table 4 is generated by feeding power to each of the electromagnetic coils 1 to 6 installed at a total of six locations on the outer periphery of the upper and lower surfaces and the outer periphery of the four side surfaces, and a DC magnetic field is formed in the apparatus. The coated tools 1 to 18 of the present invention were produced by vapor-depositing the modified (Ti, Al) N layer having the target composition and target layer thickness shown in Tables 5 to 7, respectively.

  For comparison purposes, a conventional (Ti, Al) N layer is deposited under exactly the same conditions as in the production of the coated tools 1 to 18 of the present invention, except that no direct-current magnetic field is formed in the apparatus during deposition. Conventionally, the conventional coated tools 1-18 were each manufactured.

Next, the modified (Ti, Al) N layer and the conventional (Ti, Al) N layer constituting the hard coating layer of the present invention coated tool and the conventional coated tool are configured using a field emission scanning electron microscope. An atomic shared lattice distribution graph was created.
That is, the constituent atomic share lattice distribution graph is a mirror image of a field emission scanning electron microscope in a state where the surfaces of the modified (Ti, Al) N layer and the conventional (Ti, Al) N layer are polished surfaces. An electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees is applied to the polished surface with an irradiation current of 1 nA to each crystal grain existing within the measurement range of the surface polished surface. Using a backscatter diffraction image apparatus, a (001) plane and a (011) plane that are crystal planes of the crystal grains with respect to the normal line of the surface-polished surface in a 30 × 50 μm region at an interval of 0.1 μm / step. The inclination angle formed by the normal of the surface is measured, and based on the measurement inclination angle obtained as a result, each of the constituent atoms is one constituent atom between the crystal grains at the interface between adjacent crystal grains. Of lattice points (constituent atom shared lattice points) that share Constituent atom shared lattice points in which N pieces of lattice points that do not share constituent atoms between the constituent atom shared lattice points are calculated (N is an even number of 2 or more in the crystal structure of the NaCl type face centered cubic crystal) When the form is expressed by ΣN + 1, it was created by obtaining the distribution ratio of each ΣN + 1 to the entire ΣN + 1 (however, the upper limit value of N is 28 in relation to the frequency).

  In the constituent atomic shared lattice distribution graphs of the various modified (Ti, Al) N layers and conventional (Ti, Al) N layers obtained as a result, the entire ΣN + 1 (N is an even number in the range of 2 to 28). Tables 5 to 7 show the distribution ratios of [Sigma] 3 in ().

In each of the above-mentioned various atomic atom sharing point distribution graphs, as shown in Tables 5 to 7, the modified (Ti, Al) N layer of the coated tool of the present invention has a distribution ratio occupied by Σ3 of 50% to While the constituent atomic shared lattice point distribution graph is 80%, the conventional (Ti, Al) N layer of the conventional coated tool has a constituent atomic shared lattice point distribution graph in which the distribution ratio of Σ3 is 30% or less. Was shown.
FIG. 4 is a graph showing the distribution of constituent atomic shared lattice points of the modified (Ti, Al) N layer of the coated tool 1 of the present invention, and FIG. 5 is a structural atom of the conventional (Ti, Al) N layer of the conventional coated tool 1. Each of the shared grid point distribution graphs is shown.

  Further, regarding the above-described coated tools 1 to 18 of the present invention and the conventional coated tools 1 to 18, the constituent layers of the hard coating layer were observed using an electron beam microanalyzer (EPMA) and an Auger spectroscopic analyzer (longitudinal section of the layer). As a result, it was confirmed that both the former and the latter were composed of a composite oxide layer of Ti and Al having substantially the same composition as the target composition. Moreover, when the thickness of the hard coating layer of these coated tools was measured using a scanning electron microscope (same longitudinal section measurement), the average layer thickness (5-point measurement) was substantially the same as the target layer thickness. Average value).

  Next, with the various coated tools described above, the present coated tools 1 to 18 and the conventional coated tools 1 to 18 are as follows in a state where each of the various coated tools is screwed to the tip of the tool steel tool with a fixing jig. Cutting tests were conducted.

About this invention coated tools 1-6 and conventional coated tools 1-6,
Cutting conditions (A-1);
Work material: JIS · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 250 m / min,
Cutting depth: 1.5 mm,
Feed: 0.24 mm / rev,
Cutting time: 3 minutes,
Dry high-speed intermittent cutting test of alloy steel under the conditions (normal cutting speed is 180 m / min),
Cutting conditions (B-1);
Work material: JIS / S50C lengthwise equal 4 round bars with vertical grooves,
Cutting speed: 280 m / min,
Cutting depth: 1.6 mm,
Feed: 0.20 mm / rev,
Cutting time: 3 minutes,
Dry high-speed intermittent cutting test of carbon steel under the conditions (normal cutting speed is 200 m / min),
Cutting conditions (C-1);
Work material: JIS / SUS304 lengthwise equidistant four round grooved round bars,
Cutting speed: 250 m / min,
Cutting depth: 2.0 mm,
Feed: 0.21 mm / rev,
Cutting time: 3 minutes,
The dry high-speed intermittent cutting test (normal cutting speed is 180 m / min) of stainless steel under the above conditions was performed, and the flank wear width of the cutting edge was measured. The measurement results are shown in Table 8.

Moreover, about this invention coated tool 7-12 and conventional coated tool 7-12,
Cutting conditions (A-2);
Work material: JIS / SNCM439 round direction bar with four equal intervals in the length direction,
Cutting speed: 250 m / min,
Cutting depth: 2.0 mm,
Feed: 0.15 mm / rev,
Cutting time: 3 minutes,
Dry high-speed intermittent cutting test of alloy steel under the conditions (normal cutting speed is 150 m / min),
Cutting conditions (B-2);
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 280 m / min,
Cutting depth: 2.5 mm,
Feed: 0.12 mm / rev,
Cutting time: 3 minutes,
Dry high-speed intermittent cutting test of carbon steel under the conditions (normal cutting speed is 180 m / min),
Cutting conditions (C-2);
Work material: JIS / SUS304 lengthwise equidistant four round grooved round bars,
Cutting speed: 240 m / min,
Cutting depth: 1.5 mm,
Feed: 0.16 mm / rev,
Cutting time: 3 minutes,
The dry high-speed intermittent cutting test (normal cutting speed is 150 m / min) of stainless steel under the above conditions was performed, and the flank wear width of the cutting edge was measured. The measurement results are shown in Table 9.

Moreover, about this invention coated tool 13-18 and conventional coated tool 13-18,
Cutting conditions (A-3);
Work material: JIS · SCM415 (HRC61) lengthwise equidistant four round grooved round bars,
Cutting speed: 180 m / min,
Cutting depth: 0.15 mm,
Feed: 0.12 mm / rev,
Cutting time: 6 minutes,
Dry high-speed intermittent cutting test (normal cutting speed is 120 m / min) of carburized and hardened alloy steel under the conditions of
Cutting conditions (B-3);
Work material: JIS · SCr420 (HRC60) lengthwise equal 4 round bars with longitudinal grooves,
Cutting speed: 200 m / min,
Cutting depth: 0.2 mm,
Feed: 0.10 mm / rev,
Cutting time: 5 minutes,
Dry high-speed intermittent cutting test (normal cutting speed is 110 m / min) of carburized and hardened chromium steel under the conditions of
Cutting conditions (C-3);
Work material: JIS / SUJ2 (HRC58) in the longitudinal direction, four equally spaced round bars,
Cutting speed: 220 m / min,
Cutting depth: 0.12 mm,
Feed: 0.08 mm / rev,
Cutting time: 3 minutes,
A dry high-speed intermittent cutting test (normal cutting speed is 130 m / min) was performed on the hardened bearing steel under the above conditions, and the flank wear width of the cutting edge was measured. The measurement results are shown in Table 10.

  From the results shown in Tables 5 to 10, all of the coated tools 1 to 18 of the present invention are modified so that the hard coating layer shows a constituent atom shared lattice point distribution graph in which the distribution ratio of Σ3 is 50% to 80% (Ti , Al) N layer, and high-speed intermittent cutting of steel and cast iron with extremely high mechanical impact, the modified (Ti, Al) N layer has superior high-temperature strength and excellent chipping resistance. As a result, the chipping occurrence of the hard coating layer is remarkably suppressed and excellent wear resistance is shown. On the other hand, the hard coating layer shows a constituent atomic shared lattice point distribution graph with a Σ3 distribution ratio of 30% or less. In the conventional coated tools 1 to 18 configured with the conventional (Ti, Al) N layer shown, since the mechanical impact resistance of the hard coating layer is insufficient in high-speed intermittent cutting, chipping is performed on the hard coating layer. Occurs in a relatively short time It is clear that the service life is reached.

  As described above, the coated tool of the present invention has an excellent hard coating layer not only for continuous cutting and interrupted cutting under normal conditions such as various steels and cast iron, but also for high-speed interrupted cutting that particularly requires high-temperature strength. It exhibits excellent chipping resistance and exhibits excellent cutting performance over a long period of time, so that it can sufficiently satisfy cutting equipment performance, labor saving and energy saving, and cost reduction. It is.

The arc ion plating apparatus used for forming the hard coating layer of the coating tool of this invention is shown, (a) is a schematic front view, (b) is a schematic plan view. It is a schematic diagram which shows the crystal structure of the NaCl type face centered cubic crystal which the (Ti, Al) N layer which comprises a hard coating layer has. It is a schematic explanatory drawing which shows the measurement aspect of the inclination angle of the (001) plane of a crystal grain and the (011) plane in the (Ti, Al) N layer which comprises a hard coating layer. 4 is a constituent atomic shared lattice point distribution graph of a modified (Ti, Al) N layer constituting the hard coating layer of the coated tool 1 of the present invention. 4 is a constituent atomic shared lattice point distribution graph of a conventional (Ti, Al) N layer constituting a hard coating layer of a conventional coated tool 1.

Claims (1)

On the surface of the tool base made of tungsten carbide based cemented carbide, titanium carbonitride based cermet, or cubic boron nitride based ultra high pressure sintered material,
In a surface-coated cutting tool formed by vapor-depositing a hard coating layer made of a composite nitride of Ti and Al having an average layer thickness of 1 to 6 μm,
When the composition formula of the hard coating layer is expressed as (Ti _1-X Al _X ) N,
0.4 ≦ X ≦ 0.6 (where X represents an atomic ratio), and
Using a field emission scanning electron microscope, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal plane of the crystal grain is normal to the surface polished surface ( The tilt angle formed by the normal lines of the (001) plane and the (011) plane is measured. In this case, the crystal grains are NaCl-type face-centered cubic crystals each having a constituent atom composed of Ti, Al, and nitrogen at lattice points. Based on the measured tilt angle obtained as a result of this, at the interface between adjacent crystal grains, each of the constituent atoms shares one constituent atom between the crystal grains (configuration The distribution of atomic shared lattice points) is calculated, and there are N lattice points that do not share constituent atoms between the constituent atomic shared lattice points (N is an even number of 2 or more in the crystal structure of NaCl-type face-centered cubic crystal). The constitutive atomic shared lattice point form is expressed as ΣN + 1 In the constituent atom shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1 (however, the upper limit value of N is 28 in relation to the frequency), the highest peak exists in Σ3, and the Σ3 A titanium aluminum nitride layer showing a constituent atom shared lattice point distribution graph in which the distribution ratio of ΣN + 1 in the whole is 50% to 80%,
A surface-coated cutting tool that exhibits excellent chipping resistance with a hard coating layer in high-speed intermittent cutting, characterized by comprising

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