JP2017030076A - Surface-coated cutting tool with hard coated layer exhibiting superior chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface- coated tool with a hard coated layer exhibiting superior chipping resistance.SOLUTION: In a surface-coated cutting tool with a hard coated layer on a tool base surface, the hard coated layer comprises at least a layer of a composite nitride layer or of a composite carbonitride represented by a composition formula:(TiAl)(CN), an average content proportion Xof Al and an average content proportion Y(each of Xand Yis an atomic ratio) of C satisfy 0.60≤X≤0.95 and 0≤Y≤0.005, pores are present on boundary layers of crystal grains constituting the composite nitride or composite carbonitride layers and, when observing cross-sections of the composite nitride or composite carbonitride layers over a range of 1 μm×1 μm with magnification 50000 times by means of a scanning type electronic microscope and calculating area proportion of the pores and average pore size of the pores, an area proportion occupied by the pores is 1% or more and is less than 20% and the average pore size of the pores is 2 to 50 nm.SELECTED DRAWING: Figure 3

Description

  The present invention is a high-speed intermittent cutting process that involves high heat generation of alloy steel and the like, and an impact load is applied to the cutting edge, and the hard coating layer has excellent chipping resistance, so that it can be used for a long time. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent cutting performance.

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 known a coated tool in which a Ti—Al-based composite nitride layer is formed by physical vapor deposition as a hard coating layer on the surface of a tool substrate (hereinafter collectively referred to as a tool substrate), These are known to exhibit excellent wear resistance.
However, the conventional coated tool formed with the Ti-Al composite nitride layer is relatively excellent in wear resistance, but it tends to cause abnormal wear such as chipping when used under high-speed intermittent cutting conditions. Accordingly, various proposals have been made for improving the hard coating layer.

For example, in Patent Document 1, a TiCN layer and an Al ₂ O ₃ layer are used as an inner layer, and a cubic structure (Ti _1-x Al _x ) including a cubic structure or a hexagonal structure is formed thereon by chemical vapor deposition. Covering the N layer (however, in atomic ratio, x is 0.65 to 0.90) as an outer layer and applying a compressive stress of 100 to 1100 MPa to the outer layer improves the heat resistance and fatigue strength of the coated tool It has been proposed to do.

Patent Document 2 discloses that the value of the Al content ratio x is 0.65 by performing chemical vapor deposition in a temperature range of 650 to 900 ° C. in a mixed reaction gas of TiCl ₄ , AlCl ₃ , and NH _3. It is described that a (Ti _1-x Al _x ) N layer having a thickness of 0.95 is formed by vapor deposition, but in this document, an Al ₂ O ₃ layer is further formed on the (Ti _1-x Al _x ) N layer. Since the purpose is to cover the layer and thereby enhance the heat insulation effect, the value of the Al content ratio x is increased from 0.65 to 0.95 by forming the (Ti _1-x Al _x ) N layer There is no disclosure of how it affects cutting performance.

In Patent Document 3, although the upper layer of the hard coating layer is not a (Ti _1-x Al _x ) N layer but a coated tool composed of an Al ₂ O ₃ layer, the upper layer of Al ₂ O _{3 is used.} By forming fine pores with a pore diameter distribution of 2 to 50 nm in the layer and having a bimodal distribution, the impact acting on the upper layer during cutting is mitigated and the heat shielding effect is exhibited. It has been proposed to improve chipping resistance and fracture resistance in high-speed intermittent cutting.

Special table 2011-513594 gazette Special table 2011-516722 gazette JP 2012-161847 A

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 tool has even more chipping resistance, chipping resistance, Abnormal damage resistance such as peel resistance is required, and excellent wear resistance over long-term use is required.
However, although the coated tool described in Patent Document 1 has a predetermined hardness and excellent wear resistance, it is inferior in toughness, so when it is used for high-speed intermittent cutting of alloy steel, etc. However, there is a problem that abnormal damage such as chipping, chipping and peeling is likely to occur, and it cannot be said that satisfactory cutting performance is exhibited.
Moreover, the the Patent Document 2 is formed deposited by chemical vapor deposition as described in _{(Ti 1-x Al x)} N layer, it is possible to increase the content ratio x of Al, also to form a cubic structure Therefore, although a hard coating layer having a predetermined hardness and excellent wear resistance can be obtained, there is a problem that the adhesion strength with the tool base is not sufficient and the toughness is inferior.
Furthermore, the coated tool described in the above-mentioned Patent Document 3 is formed with microvoids in the upper Al ₂ O ₃ layer, so that the impact during cutting is alleviated to some extent. When the load becomes more severe due to the cutting edge, there is a problem that the thermal shock resistance and chipping resistance are insufficient.
Accordingly, the present invention provides a coated tool that has excellent chipping resistance and exhibits excellent cutting performance over a long period of use even when subjected to high-speed intermittent cutting of alloy steel and the like. With the goal.

  From the above viewpoint, the present inventors have formed a coating formed by chemical vapor deposition of a hard coating layer including at least a composite nitride or composite carbonitride (hereinafter sometimes referred to as “TiAlCN”) of Ti and Al. As a result of intensive research to improve the chipping resistance of the tool, the following findings were obtained.

  That is, the present inventors can form pores (micropores) along the grain boundary of the TiAlCN layer by depositing TiAlCN under a limited condition, and further, formed in the layer. By optimizing the average area ratio of pores and the average pore diameter, it becomes possible to suppress the progress of cracks that propagate through the grain boundaries, and as a result, such as alloy steel with high load acting on the cutting edge. It has been found that excellent chipping resistance can be exhibited by high-speed intermittent cutting.

  Further, regarding TiAlCN crystal grains having a NaCl-type face-centered cubic structure (hereinafter sometimes simply referred to as “cubic structure”) constituting the TiAlCN layer, the TiAlCN crystal grains { When the inclination angle frequency distribution of the normal of the 100} plane is obtained, the TiAlCN layer maintains the cubic structure by setting the frequency within the range of 0 to 12 degrees to 35% or more of the entire frequency. It has been found that since it has high hardness and adhesion to the tool base (or lower layer) is improved, chipping resistance and wear resistance are further improved.

Further, there is a periodic concentration change of Ti and Al in the TiAlCN crystal grains having the cubic structure (that is, the composition in the TiAlCN crystal grains is expressed by a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), x is not a constant value but a value that varies periodically), and the average value of the maximum values of the periodically changing value of the Al content ratio x is represented by X _max Further, if the average value of the minimum value of the periodically value varying x in proportion x of Al was set to _{X min,} the difference Δx of _{X max} and _{X min} is 0.03 to 0.25, wherein In the cubic structure TiAlCN crystal grains having periodic concentration changes, the period along the normal direction of the tool substrate surface is 3 to 100 nm, which causes distortion in the cubic structure TiAlCN crystal grains. Increasing the hardness and toughness of the layer, Chipping resistance, fracture resistance, wear resistance can be improved.

The present invention has been made based on the above findings,
“(1) Surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base made of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultra-high pressure sintered body In
(A) The hard coating layer includes at least a composite nitride or composite carbonitride layer of Ti and Al having an average layer thickness of 1 to 20 μm,
(B) The composite nitride or composite carbonitride layer includes at least a composite nitride or composite carbonitride phase having a NaCl-type face-centered cubic structure,
(C) The composite nitride or composite carbonitride layer is
Composition formula: (Ti _1-x Al _x ) (C _y N _1-y )
The average content ratio X _avg in the total amount of Ti and Al in Al and the average content ratio Y _avg in the total amount of C and N in C (where X _avg and Y _avg are both atomic ratios) Satisfy 0.60 ≦ X _avg ≦ 0.95 and 0 ≦ Y _avg ≦ 0.005, respectively.
(D) There are pores at grain boundaries of the crystal grains constituting the composite nitride or composite carbonitride layer, and the area ratio and average occupied by pores in the cross section of the composite nitride or composite carbonitride layer A surface-coated cutting tool characterized in that when the pore diameter is calculated, the area ratio of the pore to the observation area is 1% or more and less than 20%, and the average pore diameter of the pore is 2 to 50 nm.
(2) For the composite nitride or composite carbonitride layer, the cross section of the composite nitride or composite carbonitride layer is observed with a scanning electron microscope in a range of 1 μm × 1 μm at a magnification of 50000, and the tool base surface When a straight line is drawn at an interval of 50 nm in the layer thickness direction parallel to the line thickness, the ratio of the number of straight lines having at least one pore on the straight line is 50% or more of the total number of straight lines, and the pores are The surface-coated cutting tool according to (1), wherein three or more straight lines not existing on the line are not continuous.
(3) For the composite nitride or composite carbonitride layer, using an electron beam backscatter diffractometer, individual crystal grains having a NaCl-type face-centered cubic structure in the composite nitride or composite carbonitride layer are used. The crystal orientation is analyzed from the longitudinal section direction of the composite nitride or composite carbonitride layer, and the inclination formed by the normal of the {100} plane that is the crystal plane of the crystal grain with respect to the normal direction of the tool substrate surface The angle is measured, and the inclination angle within the range of 0 to 45 degrees with respect to the normal direction of the surface of the tool substrate is divided for each pitch of 0.25 degrees, and the frequency existing in each section When the inclination angle frequency distribution is calculated and the maximum peak is present in the inclination angle section within the range of 0 to 12 degrees, the sum of the frequencies existing within the range of 0 to 12 degrees is the inclination angle. Characterized by showing a ratio of 35% or more of the total frequency in the number distribution The surface-coated cutting tool according to (1) or (2).
(4) In the composite nitride or composite carbonitride layer, there are crystal grains having a NaCl-type face-centered cubic structure in which periodic concentration changes of Ti and Al exist, and the concentration change cycle is 3 to 3. The average value of the maximum value of the Al content ratio x, which is 100 nm, and periodically changes, is X _max , and the average value of the minimum value of the Al content ratio x, which changes periodically, is X _min The surface-coated cutting tool according to any one of (1) to (3), wherein a difference Δx between X _max and X _min is 0.03 to 0.25.
(5) When the composite nitride or composite carbonitride layer is observed from the longitudinal cross-sectional direction of the layer, individual crystals having a NaCl-type face-centered cubic structure in the composite nitride or composite carbonitride layer There are fine crystal grains having a hexagonal crystal structure at the grain boundary portion of the columnar structure composed of grains, and the area ratio of the fine crystal grains is 5% by area or less, and the average grain size R of the fine crystal grains is The surface-coated cutting tool according to any one of (1) to (4), which is 0.01 to 0.3 μm.
(6) One of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer between the tool base and the composite nitride or composite carbonitride layer or The surface-coated cutting tool according to any one of (1) to (5), wherein a lower layer is formed of two or more Ti compound layers and has a total average layer thickness of 0.1 to 20 μm.
(7) The upper layer including at least an aluminum oxide layer is present at an upper portion of the composite nitride or composite carbonitride layer with a total average layer thickness of 1 to 25 μm. (1) to (6) The surface coating cutting tool in any one. "
It has the characteristics.

  The present invention will be described in detail below.

Average thickness of the TiAlCN layer:
In FIG. 1, the cross-sectional schematic diagram of the composite nitride or composite carbonitride (TiAlCN) layer of Ti and Al of this invention is shown.
The hard coating layer of the present invention includes at least a composite nitride or composite carbonitride (TiAlCN) layer of Ti and Al represented by a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ). . This TiAlCN layer has high hardness and excellent wear resistance, but the effect is particularly prominent when the average layer thickness is 1 to 20 μm. The reason is that if the average layer thickness is less than 1 μm, the layer thickness is so thin that sufficient wear resistance over a long period of time cannot be ensured. On the other hand, if the average layer thickness exceeds 20 μm, the TiAlCN layer The crystal grains are likely to be coarsened and chipping is likely to occur. Therefore, the average layer thickness was set to 1 to 20 μm.

Composition of TiAlCN layer:
In the TiAlCN layer of the present invention, the average content ratio X _avg in the total amount of Ti and Al in Al and the average content ratio Y _avg in the total amount of C and N in C (where X _avg and Y _avg are both atoms) The ratio is controlled so as to satisfy 0.60 ≦ X _avg ≦ 0.95 and 0 ≦ Y _avg ≦ 0.005, respectively.
The reason is that when the average content ratio X _{avg of} Al is less than 0.60, the TiAlCN layer is inferior in oxidation resistance, so when it is subjected to high-speed intermittent cutting such as alloy steel, the wear resistance is not sufficient. . On the other hand, when the average content ratio X _{avg of} Al exceeds 0.95, the precipitation amount of hexagonal crystals inferior in hardness increases and the hardness decreases, so that the wear resistance decreases. Therefore, the average content ratio X _avg of Al was determined as 0.60 ≦ X _avg ≦ 0.95.
Further, when the average content ratio Y _avg of the C component contained in the TiAlCN layer is a minute amount in the range of 0 ≦ Y _avg ≦ 0.005, the adhesion between the TiAlCN layer and the tool substrate or the lower layer is improved, and By improving the lubricity, the impact during cutting is relieved, and as a result, the fracture resistance and chipping resistance of the TiAlCN layer are improved. On the other hand, when the average content ratio Y _{avg of the} component C is out of the range of 0 ≦ Y _avg ≦ 0.005, the toughness of the TiAlCN layer is lowered, so that the chipping resistance and chipping resistance are adversely lowered. Therefore, the average content ratio Y _avg of C was determined as 0 ≦ Y _avg ≦ 0.005. However, the content ratio of C excludes the inevitable content ratio of C that is included without intentionally using a gas containing C as a gas raw material. Specifically, the content ratio (atomic ratio) of the C component contained in the TiAlCN layer when the supply amount of C ₂ H ₄ is 0 is determined as an unavoidable C content ratio, and C ₂ H ₄ is intentionally determined. A value obtained by subtracting the unavoidable C content from the content (atom ratio) of the C component contained in the TiAlCN layer obtained when supplied was determined as Y _avg .

Pore present in the TiAlCN layer:
FIG. 2 shows a partially enlarged view of the TiAlCN layer of the present invention.
As shown in FIG. 2, in the TiAlCN layer of the present invention, pores having a predetermined average pore diameter are formed along the grain boundary of the layer, and cracks are generated in the layer due to a high load during cutting. Even in this case, the presence of such pores suppresses cracks from growing along the grain boundary, and as a result, it is excellent even in high-speed intermittent cutting conditions such as alloy steel in which a high load acts on the cutting edge. Demonstrates excellent chipping resistance.
If the average pore diameter of the pores is less than 2 nm, the effect of suppressing crack growth is not sufficient. On the other hand, if the average pore diameter is greater than 50 nm, the hardness of the TiAlCN layer is locally reduced, which tends to be the starting point of cracks. Chipping and chipping resistance are reduced.
Therefore, the average pore diameter of the pores formed along the grain boundary of the TiAlCN layer is set to 2 nm or more and 50 nm or less.
Further, if the area ratio of the pore is less than 1%, the effect of suppressing the progress of cracks cannot be sufficiently obtained, and if it exceeds 20%, the hardness of the TiAlCN layer is reduced due to pores, and the crack starting point is increased. In addition, since the chipping resistance and the chipping resistance are reduced due to a decrease in wear resistance, the pore area ratio is set to 1% or more and less than 20%.

Here, the area ratio of pores and the average pore diameter can be calculated by the following method.
FIG. 2 is a schematic explanatory diagram for measuring the area ratio of pores.
As shown in FIG. 2, an arbitrary 1 μm × 1 μm region in the longitudinal section of the polished TiAlCN layer is used as an observation region and observed with a scanning electron microscope with a magnification of 50000 times. The pores and non-pore areas are identified and colored by Photoshop (registered trademark) of (Registered Trademark) Co., Ltd. and others known in the art.
Then, by measuring the total area colored, the ratio of the total area colored to the observation area becomes the pore area ratio. In addition, the circle or ellipse identified as a pore is counted, and the total area of the pore is divided by the total number to calculate the average area per pore, and the diameter of the circle having that area is calculated. The value was taken as the average pore diameter.

Further, in the TiAlCN layer of the present invention, the proportion of straight lines where pores exist on the created straight line is 50% or more, and three or more straight lines where pores do not exist on the line do not exist continuously. Since there are pores that suppress crack growth in the inside, pores do not segregate and exist, and the effect of crack growth suppression is greater, so the proportion of straight lines where pores exist on the created straight line It is desirable that there are no three or more straight lines that are 50% or more of the straight line and the pores do not exist on the line.

Here, FIG. 3 shows a schematic explanatory diagram for confirming the presence or absence of pore segregation.
As shown in FIG. 3, first, an arbitrary 1 μm × 1 μm region in the longitudinal section of the polished TiAlCN layer is used as an observation region and observed with a scanning electron microscope with a magnification of 50000 times. The schematic diagram shown in FIG. 3 is an example of an observation region of 1 μm × 1 μm.
In the observation region, a plurality of pores are observed as shown as black circles and white circles in FIG.
Next, with respect to the observation region, straight lines parallel to the tool base surface and parallel to the layer thickness direction at intervals of 50 nm are drawn, and 21 straight lines are created together with the straight lines at both ends.
In FIG. 3, pores existing on the straight line are shown as black circles, while pores located off the straight line are shown as white circles, and the black circles count straight lines existing on the line.

Tilt angle number distribution of normal line of {100} plane of crystal grains having cubic structure in TiAlCN layer:
With respect to the TiAlCN layer of the present invention, when the crystal orientation of each crystal grain having a cubic structure is analyzed from the longitudinal sectional direction using an electron beam backscattering diffractometer, the normal of the tool base surface (the tool base surface and The inclination angle (see FIGS. 4 (a) and 4 (b)) formed by the normal line of the {100} plane that is the crystal plane of the crystal grain is measured. On the other hand, when the inclination angles within the range of 0 to 45 degrees are divided into the pitches of 0.25 degrees and the frequencies existing in the respective sections are totaled, the inclination angles within the range of 0 to 12 degrees are the highest. The TiAlCN layer in the case where the TiAlCN layer is present when a peak is present and the sum of the frequencies existing in the range of 0 to 12 degrees indicates a tilt angle number distribution form in which the total frequency in the tilt angle frequency distribution is 35% or more. Has a high hardness while maintaining the cubic structure. , Moreover, adhesion between the TiAlCN layer and the tool substrate or the lower layer by the inclined angle frequency distribution form as described above is remarkably improved.
Therefore, it is desirable that the crystal grains having the cubic structure of the TiAlCN layer of the present invention have the above-described inclination angle number distribution form.
FIG. 5 is a graph showing an example of the tilt angle number distribution measured by the above method for the crystal grains having the cubic structure of the TiAlCN layer of the present invention.

Changes in the concentration of Ti and Al present in the crystal grains having a cubic structure in the TiAlCN layer:
FIG. 6 is a schematic diagram showing that there is a periodic concentration change of Ti and Al in the crystal grains having the cubic structure of the TiAlCN layer of the present invention.
When a crystal having a cubic structure in the TiAlCN layer of the present invention is represented by a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), periodic concentration changes of Ti and Al in the crystal grains (Ie, when x and y are not constant values but values that change periodically), the crystal grains are distorted and the hardness is improved. However, the average value of the maximum value of the periodically changing x value of the Al content ratio x in the composition formula, which is an index of the change in the concentration of Ti and Al, is X _max , and the Al content ratio x Assuming that the average value of the minimum values of x that periodically change is X _min , if the difference Δx between X _max and X _min is smaller than 0.03, the strain formed in the crystal grains is small and sufficient hardness Improvement is not expected. On the other hand, if the difference Δx between X _max and X _min exceeds 0.25, the distortion of the crystal grains becomes too large, lattice defects become large, and the hardness decreases. Therefore, regarding the change in the concentration of Ti and Al present in the crystal grains having a cubic structure, the difference Δx between X _max and X _min is preferably 0.03 to 0.25.
Further, when the periodic concentration change of Ti and Al is less than 3 nm, the toughness is lowered. On the other hand, if the thickness exceeds 100 nm, the effect of improving the hardness cannot be expected. Therefore, the period of concentration change is desirably 3 to 100 nm.

Fine-grained hexagonal crystals present at grain boundaries of the crystal grains having a cubic structure in the TiAlCN layer:
The TiAlCN layer of the present invention can contain fine crystal grains having a hexagonal structure at the cubic grain boundaries of the columnar structure, but the presence of fine hexagonal crystals having excellent toughness at the cubic grain boundaries of the columnar structure. With this, grain boundary sliding is suppressed and toughness is improved. At this time, if the area ratio of the fine crystal grains having a hexagonal crystal structure exceeds 5% by area, the hardness is relatively lowered, and the average crystal grain size R of the fine crystal grains having a hexagonal crystal structure is less than 0.01 μm. If it is, the effect of improving toughness is not seen, and if it exceeds 0.3 μm, the hardness decreases and the wear resistance is impaired, so the average particle size R is preferably 0.01 to 0.3 μm. .
Incidentally, the hexagonal structure fine grains existing in the grain boundary referred to in the present invention can be identified by analyzing the electron diffraction pattern using a transmission electron microscope, and the hexagonal structure fine grains. The average particle diameter of the crystal grains can be obtained by measuring the particle diameters of the particles existing within the measurement range of 1 μm × 1 μm including the grain boundaries and calculating the average value thereof.

Method for forming a TiAlCN layer of the present invention:
The TiAlCN layer provided with the component composition, pore area ratio / average pore diameter, gradient angle number distribution, periodic concentration change, and hexagonal fine crystal grains defined in the present invention is formed by chemical vapor deposition under the following film formation conditions. The film can be formed by the method. The pores present in the TiAlCN layer of the present invention vary in pore formation depending on the feed rate and feed rate of the source gas, and the pore area ratio and average pore size change the ratio of the metal feed gas and the feed cycle. Can be controlled.
[Film formation conditions]
Reaction gas composition (volume%):
Gas group A: NH ₃ 1.0 to 2.0%, H ₂ 65 to 75%,
Gas group B: AlCl ₃ 0.2 to 0.4%, TiCl ₄ 0.08 to 0.10%, N ₂ : 0 to 12%, C ₂ H _{4 0 to} 0.05%, H ₂ : remaining,
Reaction atmosphere pressure: 4.0 to 5.0 kPa,
Supply cycle: 10 to 30 seconds,
Gas supply time per cycle: 0.5 to 2.0 seconds,
Phase difference between supply of gas group A and supply of gas group B: 0.5 to 1.0 second,

Lower layer and upper layer:
Although the TiAlCN layer of the present invention alone has a sufficient effect, one or two or more layers of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer can be obtained. When a lower layer comprising a compound layer and having a total average layer thickness of 0.1 to 20 μm is provided, and / or when an upper layer including at least an aluminum oxide layer is provided with a total average layer thickness of 1 to 25 μm Combined with the effect of these layers, it can create better properties. When providing a lower layer made of one or two or more Ti compound layers of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride oxide layer, the total average layer of the lower layer If the thickness is less than 0.1 μm, the effect of the lower layer is not sufficiently achieved. On the other hand, if it exceeds 20 μm, the crystal grains are likely to be coarsened and chipping is likely to occur. Further, if the total average layer thickness of the upper layer including at least the aluminum oxide layer is less than 1 μm, the effect of the upper layer is not sufficiently achieved. On the other hand, if it exceeds 25 μm, the crystal grains are likely to be coarsened and chipping is likely to occur. Become.

The present invention provides a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base, wherein the hard coating layer includes at least a TiAlCN layer, and the TiAlCN is represented by a composition formula: (Ti _1-x Al _x ) (C _y N _1-y ), the average content ratio X _avg in the total amount of Ti and Al in Al and the average content ratio Y _avg in the total amount of C and N in C are 0.60 ≦ X, respectively. _avg ≦ 0.95, 0 ≦ Y _avg ≦ 0.005 (where X _avg and Y _avg are both atomic ratios), and the crystal grains constituting the TiAlCN layer have a cubic structure In addition, the presence of pores having a predetermined area ratio and average pore diameter in the TiAlCN layer suppresses the propagation and propagation of cracks along the grain boundary, so that an alloy steel with a high load acting on the blade edge, etc. High-speed intermittent In processing, it exhibits excellent chipping resistance.
Further, the present invention provides a tilt angle number distribution of the normal line of the {100} plane measured for the TiAlCN crystal grains having a cubic structure constituting the TiAlCN layer, and 0 to 12 with respect to the normal direction of the tool base surface. By setting the power within the degree range to 35% or more of the whole power, adhesion to the tool base (or lower layer) is improved, and chipping resistance and wear resistance are further improved.
Further, in the present invention, since the TiAlCN crystal grains having the cubic structure have periodic concentration changes of Ti and Al, the crystal grains are distorted, and the hardness and toughness of the TiAlCN layer are increased. As a result, chipping resistance, chipping resistance, and wear resistance are further improved. And, when the coated tool of the present invention is provided with the above-mentioned hard coating layer, even when used for high-speed intermittent cutting such as alloy steel in which intermittent and impact loads act on the cutting edge, the hard coating layer is It exhibits excellent chipping resistance and chipping resistance, and as a result, exhibits excellent cutting performance over a long period of use.

It is the film | membrane structure schematic schematic diagram which represented typically the cross section of the TiAlCN layer of this invention. FIG. 2 is a partially enlarged view of the TiAlCN layer shown in FIG. 1 and shows a state in which pores are formed at grain boundaries. FIG. 3 is a schematic explanatory diagram for confirming the presence or absence of pore segregation in the partially enlarged view of the TiAlCN layer shown in FIG. 2. The inclination angle formed by the normal of the {100} plane, which is the crystal plane of the cubic TiAlCN crystal grains, with respect to the normal of the tool base surface (the direction perpendicular to the tool base surface on the cross-section polished surface) is (a) 0 In the case of degrees, (b) is a schematic diagram showing a case of 45 degrees. It is a graph which shows an example of inclination angle number distribution of the crystal grain which has measured the cross section of the TiAlCN layer of this invention, and has a cubic structure. It is the schematic diagram showing that the periodic composition change of Ti and Al exists in the cross section of the TiAlCN layer of this invention.

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

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, manufacture tool bases A to C made of WC-base cemented carbide with ISO standard SEEN1203AFSN insert shape, respectively. did.

In addition, as raw material powders, all TiCN (mass ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, WC powder, Co powder 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 D made of TiCN-based cermet having an ISO standard SEEN1203AFSN insert shape was produced.

Next, a chemical vapor deposition apparatus is used on the surfaces of these tool bases A to D,
Formation conditions A to H shown in Table 4, that is, a gas group A composed of NH ₃ and H ₂ , a gas group B composed of AlCl ₃ , TiCl ₄ , C ₂ H ₄ and H ₂ , and supply of each gas As a method, the reaction gas composition (capacity% with respect to the total of the gas group A and the gas group B) is set as the gas group A: NH ₃ : 1.0 to 2.0%, H ₂ : 70 to 80%, gas group As B, AlCl ₃ : 0.03 to 0.05%, TiCl ₄ : 0.01 to 0.02%, N ₂ : 0 to 12%, C ₂ H ₄ : 0 to 0.05%, H ₂ : remaining , Reaction atmosphere pressure: 4.5 to 5.0 kPa, reaction atmosphere temperature: 700 to 900 ° C., supply cycle 10 to 30 seconds, gas supply time 0.5 to 2.0 seconds per cycle, supply of gas group A And a gas phase B supply phase difference of 0.5 to 1.0 second, for a predetermined time, heat CV Law was performed to produce the present invention coated tool 12 by depositing TiAlCN layer shown in Table 6.
In addition, about this invention coated tools 5-12, the lower layer and upper layer which were shown in Table 5 were formed on the formation conditions shown in Table 3.

Further, for the purpose of comparison, the coated tools 1 to 4 of the present invention are formed on the surfaces of the tool bases A to D with the target layer thickness (μm) shown in Table 7 under the conditions of the comparative film forming process shown in Tables 3 and 4. 12, comparative coating tools 1 to 12 were produced by vapor-depositing a hard coating layer containing at least a TiAlCN layer. At this time, comparative coating tools 1 to 12 were manufactured by forming a hard coating layer so that the reaction gas composition on the surface of the tool base did not change with time during the TiAlCN layer forming step.
In addition, similarly to this invention coated tools 5-12, about the comparative coated tools 5-12, the lower layer and upper layer which were shown in Table 5 were formed on the formation conditions shown in Table 3.

Next, the cross section in the direction perpendicular to the tool base of each component layer of the coated tools 1 to 12 and comparative coated tools 1 to 12 of the present invention is measured using a scanning electron microscope (magnification 5000 times), and within the observation field of view. When the five layer thicknesses were measured and averaged to determine the average layer thickness, all showed the same average layer thickness as the target layer thicknesses shown in Tables 6 and 7.
Further, the average Al content ratio X _avg of the TiAlCN layer was obtained by irradiating an electron beam from the sample surface side in a sample whose surface was polished using an electron beam microanalyzer (EPMA, Electron-Probe-Micro-Analyser). The average Al content ratio X _avg of Al was determined from the 10-point average of the obtained characteristic X-ray analysis results. About average C content rate _Yavg, it calculated | required by secondary ion mass spectrometry (SIMS, Secondary-Ion-Mass-Spectroscopy). The ion beam was irradiated in the range of 70 μm × 70 μm from the sample surface side, and the concentration in the depth direction was measured for the components emitted by the sputtering action. The average C content ratio Y _avg indicates the average value in the depth direction for the TiAlCN layer. However, the content ratio of C excludes the inevitable content ratio of C that is included without intentionally using a gas containing C as a gas raw material. Specifically, the content ratio (atomic ratio) of the C component contained in the TiAlCN layer when the supply amount of C ₂ H ₄ is 0 is determined as an unavoidable C content ratio, and C ₂ H ₄ is intentionally determined. A value obtained by subtracting the unavoidable C content from the content (atom ratio) of the C component contained in the TiAlCN layer obtained when supplied was determined as Y _avg .
Tables 6 and 7 show the values of X _avg and Y _avg .

Next, for the inventive coated tools 1-12 and comparative coated tools 1-12, the longitudinal section of the TiAlCN layer was observed with a scanning electron microscope at a magnification of 50000 times, and the observation area was 1 μm × 1 μm. For the region, straight lines were drawn parallel to the surface of the tool substrate and parallel to the layer thickness direction at intervals of 50 nm.
As shown in FIG. 2, a portion of the obtained image identified as a pore using image processing software was colored, the total area colored was measured, and the area ratio of the pore to the observation area was calculated. . Also, by counting the circles or ellipses identified as pores, dividing the total area of the pores by the total number, the average area per pore is calculated, and the pores obtained from the diameter of the circle having that area The average pore diameter was calculated. Then, the pore area ratio and the average pore diameter measured in 10 observation regions were calculated as the pore area ratio and the pore average pore diameter, respectively.
Also, the number of straight lines with pores on the created straight line is counted, and the ratio of the number of straight lines with pores measured in 10 observation areas is calculated, and there is no pore in each observation area. It was confirmed whether three or more straight lines were not continuous.
Tables 6 and 7 show the results.

Also, regarding the tilt angle number distribution of the TiAlCN layer, with the cross section of the TiAlCN layer in the direction perpendicular to the surface of the tool base as a polished surface, it is set in a lens barrel of a field emission scanning electron microscope, and the polished surface is An electron backscatter diffraction image apparatus is irradiated with an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees and with an irradiation current of 1 nA on each crystal grain having a cubic crystal lattice existing within the measurement range of the cross-section polished surface. At a distance of 0.01 μm / step with respect to the TiAlCN layer within a measurement range of a distance of 100 μm or less in the horizontal direction from the tool substrate surface and a thickness equal to or less than the film thickness along a cross section in a direction perpendicular to the tool substrate surface, The inclination angle formed by the normal of the {100} plane, which is the crystal plane of the crystal grain, is measured with respect to the normal of the substrate surface (in the direction perpendicular to the substrate surface on the cross-section polished surface). The above Of the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are divided for each pitch of 0.25 degrees, and by counting the frequencies existing in each section, the range of 0 to 12 degrees The presence or absence of a frequency peak existing in the interior was confirmed, and the ratio of the frequency existing in the range of 0 to 12 degrees was determined.
Tables 6 and 7 show the results.

In addition, using a transmission electron microscope (magnification 200000 times), a micro region of the TiAlCN layer is observed under the condition of an acceleration voltage of 200 kV, and surface analysis is performed from the cross-sectional side using energy dispersive X-ray spectroscopy (EDS). In the crystal grains having the cubic structure, a periodic concentration change of Ti and Al in the composition formula: (Ti _1-x Al _x ) (C _y N _1-y ) exists. confirmed.
Furthermore, for the crystal grains having the cubic structure in which the periodic concentration change exists, the microscopic region is observed using the transmission electron microscope and the cross section side using the energy dispersive X-ray spectroscopy (EDS) is used. In the surface analysis, the period of concentration change is measured, and the average value of the local maximum value of x in the period of x of 5 cycles of the crystal grains having a cubic structure existing in the TiAlCN layer is defined as X _max , the average value of the minimum value of x and _{X min} in the period of the same five cycles of x, was determined and the difference _{Δx (= X max -X min)} .

About the TiAlCN layer which comprises the hard coating layer of the said invention coating tool 1-12 and the comparative coating tool 1-12, it observes over several visual fields using a transmission electron microscope, and consists of a crystal grain which has a cubic structure. The area ratio of the fine crystal grains having a hexagonal structure existing in the grain boundary portion of the columnar structure was measured, and the average particle diameter R of the fine crystal grains having the hexagonal structure was measured.
In addition, the identification of the fine-grained hexagonal crystal which exists in the grain boundary as used in the field of this invention was identified by analyzing an electron beam diffraction pattern using a transmission electron microscope. The average particle size of the fine hexagonal crystals was determined by measuring the particle size of particles present in the measurement range of 1 μm × 1 μm including the grain boundaries and calculating the total area of the fine hexagonal crystals. For the grain size, a circumscribed circle was created for the grains identified as hexagonal crystals, the radius of the circumscribed circle was determined, and the average value was taken as the grain size.

Next, the present invention coated tools 1 to 12 and comparative coated tools 1 to 12 are described below in a state where each of the various coated tools is clamped to a tool steel cutter tip portion having a cutter diameter of 125 mm by a fixing jig. The dry high-speed face milling, which is a kind of high-speed interrupted cutting of alloy steel, and a center-cut cutting test were performed, and the flank wear width of the cutting blade was measured.
The results are shown in Table 8.

Tool substrate: Tungsten carbide-based cemented carbide, titanium carbonitride-based cermet,
Cutting test: Dry high-speed face milling, center cutting,
Work material: JIS / SCM440 block material with a width of 100 mm and a length of 400 mm,
Rotational speed: 994 min ⁻¹
Cutting speed: 390 m / min,
Cutting depth: 1.5 mm,
Single-blade feed amount: 0.15 mm / tooth,
Cutting time: 8 minutes,
(Normal cutting speed is 220 m / min),

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. Blended in the composition shown in Table 9, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, pressed into a green compact of a predetermined shape at a pressure of 98 MPa. In a 5 Pa vacuum, vacuum sintering is performed at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour, and after sintering, the cutting edge is subjected to honing processing with an R of 0.07 mm. Tool bases α to γ made of a WC-base cemented carbide having an insert shape of CNMG12041 were manufactured.

  In addition, as raw material powder, TiCN (mass ratio TiC / TiN = 50/50) powder, NbC powder, WC powder, Co powder, and Ni powder all having an average particle diameter of 0.5 to 2 μm are prepared, These raw material powders were blended into the composition shown in Table 10, wet mixed for 24 hours with a ball mill, dried, and then pressed into a green compact at a pressure of 98 MPa. Sintered in an atmosphere at a temperature of 1500 ° C. for 1 hour, and after sintering, the cutting edge part is subjected to a honing process of R: 0.09 mm so that the TiCN base has an insert shape of ISO standard / CNMG120212 A cermet tool substrate δ was formed.

Next, on the surfaces of these tool bases α to γ and tool base δ, using a normal chemical vapor deposition apparatus, formation conditions A to H shown in Table 4, that is, a gas group A composed of NH ₃ and H ₂ , , AlCl ₃ , TiCl ₄ , C ₂ H ₄ , H ₂ , and a method for supplying each gas, the reaction gas composition (capacity% relative to the total of the gas group A and the gas group B) NH ₃ as group A: 1.0 to 2.0%, H ₂ : 70 to 80%, AlCl ₃ as gas group B: 0.03 to 0.05%, TiCl ₄ : 0.01 to 0.02% , N ₂ : 0 to 12%, C ₂ H ₄ : 0 to 0.05%, H ₂ : remaining, reaction atmosphere pressure: 4.5 to 5.0 kPa, reaction atmosphere temperature: 700 to 900 ° C, supply cycle 10 ~ 30 seconds, gas supply time per cycle 0.5 ~ 2.0 seconds, The present invention is performed by forming a TiAlCN layer shown in Table 12 by performing a thermal CVD method for a predetermined time with a phase difference of 0.5 to 1.0 seconds between the supply of gas group A and the supply of gas group B. Coated tools 13-24 were produced.
In addition, about this invention coated tools 16-24, the lower layer and upper layer which were shown in Table 11 on the formation conditions shown in Table 3 were formed.

For comparison purposes, the present invention is also applied to the surfaces of the tool bases α to γ and the tool base δ by using an ordinary chemical vapor deposition apparatus under the conditions shown in Tables 3 and 4 and the target layer thicknesses shown in Table 13. Comparative coating tools 13 to 24 shown in Table 13 were manufactured by vapor-depositing a hard coating layer in the same manner as the coating tool.
In addition, similarly to this invention coating | coated tool 16-24, about the comparison coating tools 16-24, the lower layer and upper layer which were shown in Table 11 on the formation conditions shown in Table 3 were formed.

The cross sections of the constituent layers of the inventive coated tools 13 to 24 and comparative coated tools 13 to 24 are measured using a scanning electron microscope (5000 times magnification), and the layer thicknesses at five points in the observation field are measured and averaged. As a result, the average layer thickness was found to be substantially the same as the target layer thickness shown in Tables 12 and 13.
For the TiAlCN layers of the inventive coated tools 13 to 24 and comparative coated tools 13 to 24, using the same method as the method shown in Example 1, the average Al content ratio X _avg and the average C content ratio Y _avg Was measured.
In addition, the pore area ratio, the average pore diameter, and the number of straight lines in which pores exist in the TiAlCN layer are calculated using a method similar to that shown in Example 1, and three or more straight lines in which pores do not exist are continuously present. I confirmed whether or not.
In addition, while confirming the inclination angle section where the peak exists in the inclination angle number distribution that the normal line of the {100} plane of the crystal grains having a cubic structure constituting the TiAlCN layer and the normal line of the tool base surface exists, The frequency ratio existing in the range of 12 degrees was measured.
Tables 12 and 13 show the results.

Further, it is confirmed that a periodic concentration distribution of Ti and Al is present in the crystal grains having the cubic structure of the TiAlCN layer of the inventive coated tools 13 to 24 and the comparative coated tools 13 to 24. (Magnification 200,000 times), and is confirmed by surface analysis by energy dispersive X-ray spectroscopy (EDS), and the average value of the local maximum value of x in the period of x for 5 periods is the minimum of X _max and x the average value of the values obtained the difference Δx ₍₌ X max _{-X min)} and the cycle of _{X min.}
Tables 12 and 13 show the results.

In addition, by analyzing the electron diffraction pattern of the TiAlCN layer using a transmission electron microscope, the hexagonal structure fine crystal grains present in the grain boundary portion of the columnar structure composed of crystal grains having a cubic structure are obtained. The area ratio and average particle size R were measured.
Tables 12 and 13 show these results.

Next, in the state where all the various coated tools are screwed to the tip of the tool steel tool with a fixing jig, the present coated tools 13 to 24 and comparative coated tools 13 to 24 are shown below. A dry high-speed intermittent cutting test for carbon steel and a wet high-speed intermittent cutting test for cast iron were performed, and the flank wear width of the cutting edge was measured for both.
Cutting condition 1:
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 390 m / min,
Cutting depth: 2.0 mm,
Feed: 0.25 mm / rev,
Cutting time: 5 minutes,
(Normal cutting speed is 220 m / min),
Cutting condition 2:
Work material: JIS / FCD700 lengthwise equal length 4 round bar with round groove,
Cutting speed: 330 m / min,
Cutting depth: 1.2 mm,
Feed: 0.1 mm / rev,
Cutting time: 5 minutes,
(Normal cutting speed is 200 m / min),
Table 14 shows the results of the cutting test.

As the raw material powder, cBN powder, TiN powder, TiCN powder, TiC powder, Al powder, and Al ₂ O ₃ powder each having an average particle diameter in the range of 0.5 to 4 μm were prepared. The mixture is blended in the composition shown in FIG. 1, wet mixed with a ball mill for 80 hours, dried, and then pressed into a green compact having a diameter of 50 mm × thickness: 1.5 mm under a pressure of 120 MPa. The green compact is sintered in a vacuum atmosphere at a pressure of 1 Pa at a predetermined temperature within a range of 900 to 1300 ° C. for 60 minutes to obtain a presintered body for a cutting edge piece. In addition, Co: 8% by mass, WC: remaining composition, and diameter: 50 mm × thickness: 2 mm, superposed on a WC-based cemented carbide support piece with a normal super-high pressure Insert into the sintering machine, normal conditions A certain pressure: 4 GPa, temperature: 1200 ° C. to 1400 ° C. within a predetermined temperature, holding time: 0.8 hour sintering, and after sintering, the upper and lower surfaces are polished with a diamond grindstone, and wire discharge It is divided into predetermined dimensions by a processing apparatus, and further Co: 5 mass%, TaC: 5 mass%, WC: remaining composition and shape of JIS standard CNGA120408 (thickness: 4.76 mm × inscribed circle diameter: 12. The brazing part (corner part) of the WC-based cemented carbide insert body having a 7 mm 80 ° rhombus) has a composition consisting of Zr: 37.5%, Cu: 25%, Ti: the rest in mass%. After brazing using a brazing material of Ti-Zr-Cu alloy and having a predetermined dimension, the cutting edge is subjected to honing with a width of 0.13 mm and an angle of 25 °, followed by finishing polishing. ISO regulations CNGA120408 tool substrate b having the insert shape, were manufactured, respectively b.

Next, a hard coating layer containing at least a TiAlCN layer is formed on the surface of these tool bases a and b under the conditions shown in Tables 3 and 4 by the same method as in Example 1 using a normal chemical vapor deposition apparatus. The present coated tools 25 to 30 shown in Table 17 were manufactured by vapor deposition with a target layer thickness.
In addition, about this invention coated tools 28-30, the lower layer and upper layer as shown in Table 16 were formed on the formation conditions shown in Table 3.

Also, for comparison purposes, a hard coating layer containing at least a TiAlCN layer is deposited at the target layer thickness under the conditions shown in Tables 3 and 4 on the surfaces of the tool bases A and B using a normal chemical vapor deposition apparatus. By forming, comparative coated tools 25-30 shown in Table 18 were produced.
In addition, similarly to this invention covering tool 28-30, about the comparison covering tool 28-30, the lower layer and upper layer as shown in Table 16 were formed on the formation conditions shown in Table 3.

  Moreover, the cross section of each component layer of this invention coated tool 25-30 and comparative coated tool 25-30 is measured using a scanning electron microscope (5000 times magnification), and the layer thickness of five points in an observation visual field is measured. When the average layer thickness was obtained by averaging, all showed the average layer thickness substantially the same as the target layer thickness shown in Table 17 and Table 18.

Moreover, about the hard coating layer of the said invention coating tool 25-30 and the comparison coating tool 25-30, using the method similar to the method shown in Example 1, average Al content rate _Xavg , average C content rate Y _avg was measured.
In addition, the pore area ratio, the average pore diameter, and the number of straight lines in which pores exist in the TiAlCN layer are calculated using a method similar to that shown in Example 1, and three or more straight lines in which pores do not exist are continuously present. I confirmed whether or not. In addition, while confirming the inclination angle section where the peak exists in the inclination angle number distribution that the normal line of the {100} plane of the crystal grains having a cubic structure constituting the TiAlCN layer and the normal line of the tool base surface exists, The frequency ratio existing in the range of 12 degrees was measured.
Further, by using a method similar to the method shown in Example 1, the average value X _max of the maximum value X _max and the minimum value of x in the periodic concentration change of Ti and Al existing in the cubic crystal grains are determined. The difference Δx (= X _max −X _min ) and the period of the average value X _min were measured.
Tables 17 and 18 show these results.

Moreover, about the hard coating layer of the said invention coating tool 25-30 and the comparison coating tool 25-30, the columnar shape which consists of a crystal grain which has a cubic structure by analyzing an electron beam diffraction pattern using a transmission electron microscope The area ratio of the fine crystal grains having a hexagonal structure existing in the grain boundary portion of the structure and the average particle diameter R were measured.
Tables 17 and 18 show these results.

Next, carburization shown below about this invention covering tool 25-30 and comparative covering tool 25-30 in the state where all the various covering tools were screwed to the front-end | tip part of a tool steel cutting tool with a fixing jig. A dry high-speed intermittent cutting test was performed on the quenched alloy steel, and the flank wear width of the cutting edge was measured.
Tool substrate: Cubic boron nitride-based ultra-high pressure sintered body,
Cutting test: Dry high-speed intermittent cutting of carburized and quenched alloy steel,
Work material: JIS · SCr420 (Hardness: HRC62) lengthwise equidistant four round bars with vertical grooves,
Cutting speed: 265 m / min,
Cutting depth: 0.12 mm,
Feed: 0.1 mm / rev,
Cutting time: 4 minutes
Table 19 shows the results of the cutting test.

From the results shown in Table 8, Table 14 and Table 19, the coated tool of the present invention has the presence of pores having a predetermined pore area ratio and average pore diameter in the TiAlCN layer, so that propagation of cracks along grain boundaries Providing excellent chipping resistance in high-speed intermittent cutting of alloy steel, etc., where progress is suppressed and a high load acts on the cutting edge.
Further, in the tilt angle frequency distribution of the normal line of the {100} plane of TiAlCN crystal grains having a cubic structure, the frequency within the range of 0 to 12 degrees with respect to the normal direction of the tool substrate surface is set to 35% of the total frequency. The above-described coated tool of the present invention has improved adhesion to the tool substrate (or lower layer), improved chipping resistance, wear resistance, and further, Ti and crystal grains having a cubic structure have Ti and The coated tool of the present invention in which the concentration change of Al is present is improved in hardness due to distortion of crystal grains, and toughness is improved while maintaining high wear resistance.
The coated tool of the present invention exhibits excellent chipping resistance and wear resistance over a long period of use in high-speed intermittent cutting of alloy steel or the like in which a high load acts on the cutting edge.

  On the other hand, the TiAlCN layer does not have the pore area ratio defined in the present invention, or the comparative coated tool having no pore having the average pore diameter defined in the present invention is accompanied by high heat generation, When used for high-speed intermittent cutting where intermittent and impactful high loads act on the cutting edge, it is clear that chipping, chipping, etc. will lead to short life.

  As described above, the coated tool of the present invention can be used not only for high-speed intermittent cutting of alloy steel but also as a coated tool for various work materials, and has excellent chipping resistance over a long period of use. Since it exhibits wear resistance, it can sufficiently satisfy the high performance of the cutting device, the labor saving and energy saving of the cutting work, and the cost reduction.

Claims (7)

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 Al having an average layer thickness of 1 to 20 μm,
(B) The composite nitride or composite carbonitride layer includes at least a composite nitride or composite carbonitride phase having a NaCl-type face-centered cubic structure,
(C) The composite nitride or composite carbonitride layer is
Composition formula: (Ti _1-x Al _x ) (C _y N _1-y )
The average content ratio X _avg in the total amount of Ti and Al in Al and the average content ratio Y _avg in the total amount of C and N in C (where X _avg and Y _avg are both atomic ratios) Satisfy 0.60 ≦ X _avg ≦ 0.95 and 0 ≦ Y _avg ≦ 0.005, respectively.
(D) There are pores at grain boundaries of the crystal grains constituting the composite nitride or composite carbonitride layer, and the cross section of the composite nitride or composite carbonitride layer is magnified by a scanning electron microscope. When observing a range of 1 μm × 1 μm at 50000 times and calculating the area ratio and the average pore diameter occupied by the pore, the area ratio occupied by the pore with respect to the observation area is 1% or more and less than 20%, and the average pore diameter of the pore is A surface-coated cutting tool having a thickness of 2 to 50 nm.   For the composite nitride or composite carbonitride layer, the cross section of the composite nitride or composite carbonitride layer was observed with a scanning electron microscope at a magnification of 50000 times in a range of 1 μm × 1 μm, and parallel to the tool substrate surface When straight lines are drawn at 50 nm intervals in the layer thickness direction, the ratio of the number of straight lines having at least one pore on the straight line is 50% or more of the total number of straight lines, and the pores are present on the line. The surface-coated cutting tool according to claim 1, wherein three or more straight lines that are not continuous are not continuous. With respect to the composite nitride or composite carbonitride layer, the crystal orientation of individual crystal grains having a NaCl-type face-centered cubic structure in the composite nitride or composite carbonitride layer is determined using an electron beam backscattering diffraction apparatus. Analyzing from the longitudinal section direction of the composite nitride or composite carbonitride layer, and measuring 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 tool substrate surface Then, the inclination angles within the range of 0 to 45 degrees with respect to the normal direction of the tool base surface among the inclination angles are divided into pitches of 0.25 degrees, and the frequencies existing in each division are totaled. When the inclination angle frequency distribution is obtained, 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 in the inclination angle number distribution. A contract characterized by a ratio of 35% or more of the entire frequency The surface-coated cutting tool according to claim 1 or 2. In the composite nitride or composite carbonitride layer, there are crystal grains having a NaCl-type face-centered cubic structure in which periodic concentration changes of Ti and Al exist, and the concentration change period is 3 to 100 nm. , the average value X _max of the maximum value of the value of the content x of Al changes _{periodically,} also when the average value of the minimum value of the values of the content x of the periodically varying Al was X _min, The surface-coated cutting tool according to any one of claims 1 to 3, wherein a difference Δx between X _max and X _min is 0.03 to 0.25.   When the composite nitride or the composite carbonitride layer is observed from the longitudinal cross-sectional direction of the layer, the composite nitride or the composite carbonitride layer is composed of individual crystal grains having a NaCl-type face-centered cubic structure in the composite nitride or the composite carbonitride layer. There are fine crystal grains having a hexagonal structure in the grain boundary portion of the columnar structure, the area ratio of the fine crystal grains is 5 area% or less, and the average grain size R of the fine crystal grains is 0.01. The surface-coated cutting tool according to any one of claims 1 to 4, wherein the surface-coated cutting tool is -0.3 µm.   Between the tool substrate and the composite nitride or composite carbonitride layer, one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer and carbonitride layer The surface-coated cutting tool according to any one of claims 1 to 5, wherein a lower layer is formed of the Ti compound layer and has a total average layer thickness of 0.1 to 20 µm. 7. The upper layer including at least an aluminum oxide layer is present at a total average layer thickness of 1 to 25 [mu] m above the composite nitride or composite carbonitride layer. Surface coated cutting tool.