JP2018144138A - Surface-coated cutting tool having hard coating layer excellent in wear resistance and chipping resistance - Google Patents

Abstract

[PROBLEMS] To exhibit excellent toughness, chipping resistance, and wear resistance even in high-speed and high-feed processing. A hard coating layer has a composition (a) (Ti1-xAlx) (CyN1-y) 0.70 ≦ x ≦ 0.95, 0 ≦ y <0.005 (b) The upper layer is formed on the surface of the substrate. Of the inclination angles formed by the normal of the {100} plane with respect to the normal line, the inclination angle of 0 to 45 degrees with respect to the normal direction is tabulated with a pitch division of 0.25 degrees, and the highest peak at 2 to 12 degrees And the total frequency of 2 to 12 degrees is 45% or more of the entire frequency, and the lower layer is in the normal direction of the inclination angle formed by the normal of the {111} plane with respect to the normal of the substrate surface. (C) The tilt angle of 0 to 45 degrees is counted in the pitch division of 0.25 degrees, the highest peak is present at 2 to 12 degrees, and the total frequency of 2 to 12 degrees is 45% or more of the entire frequency. The average thickness of the upper layer and the lower layer is 0.5 to 10 μm, and (d) the surface layer in which the lower layer is exposed at the edge of the cutting edge. Cutting tools. [Selection] Figure 5

Description

The present invention provides a hard coating layer with excellent chipping resistance when carbon steel, alloy steel, cast iron, etc. are machined under high-speed and high-feed conditions in which a high load acts on the cutting edge with high heat generation. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent wear resistance.

Conventionally, for the purpose of improving the cutting performance of cutting tools, 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). ) A coated tool in which a Ti-Al based composite nitride layer is formed as a hard coating layer on the surface of a substrate (hereinafter collectively referred to as a substrate) composed of a super-high pressure sintered body by vapor deposition. These are known to exhibit excellent wear resistance.
Although the conventional coated tool formed by coating the conventional Ti-Al based composite nitride layer is relatively excellent in wear resistance, it is hard to cause abnormal wear such as chipping when used under high-speed cutting conditions. Various proposals for improving the coating layer have been made.

For example, in Patent Document 1, when a longitudinal cross section of a composite carbonitride layer of the composition formula: (Ti _1-x Al _x ) (C _y N _1-y ) on the tool base surface is analyzed by EBSD (1) The frequency distribution of the tilt angle formed by the normal of the {111} plane in the range of 2 to 12 degrees is 45% or more of the entire tilt angle number distribution, and (2) the composite carbonitride from the substrate interface. The distribution of constituent atomic shared lattice points of Ti, Al, C, and N, which are constituent elements, is calculated by FE-SEM observation in the range of 0.1 to 0.5 μm to the layer, When N lattice points that do not share constituent atoms are represented by ΣN + 1, a coated tool is described in which the distribution ratio of Σ5 is 30% or more and the distribution peak exists in Σ5.

In Patent Document 2, a first unit layer made of TiN and a second unit layer made of Ti _1-x Al _x N (0.6 ≦ x ≦ 0.9) are alternately laminated, A coated tool in which the unit layer is oriented in the (111) plane is described.

Further, Patent Document 3 includes an upper layer in which a periodic composition change of Ti and Al exists on the tool base surface and a lower layer in which no periodic composition change exists, and the upper layer has a composition formula: (Ti _1- xAl _x ) (C _y N _1-y ), 0.70 ≦ x ≦ 0.95 and I (200) / I (111)> 10, and the lower layer is composed of When expressed by the formula: (Ti _1-u Al _u ) (C _v N _1-v ), 0 ≦ u <0.70 and 0 ≦ v ≦ 0.005, I (200) / I (111) A coated tool is described in which <3 and u increases sequentially from the tool substrate surface to the upper layer.

JP 2014-24131 A Japanese Patent Laying-Open No. 2015-52133 JP 2006-168669 A

In recent years, there has been a strong demand for energy saving and energy saving in cutting, and along with this, cutting has become a trend toward higher speed, higher feed and higher efficiency. Further, abnormal damage resistance such as chipping resistance, chipping resistance, and peeling resistance is required, and excellent wear resistance is required for long-term use.
However, in the coated tool described in Patent Document 1, the frequency distribution of the tilt angle formed by the normal of the {111} plane is in the range of 2 to 12 degrees is 45% or more of the entire tilt angle number distribution. Therefore, the chipping resistance is improved, but the chipping resistance may be insufficient in high-speed and high-feed machining.

  Moreover, although the coated tool described in Patent Document 2 shows excellent wear resistance in dry milling of alloy steel, it cannot be said that chipping resistance is sufficient in severe dry milling such as high speed and high feed. Tool life is shortened.

  Furthermore, the coated tool described in Patent Document 3 has excellent peeling resistance of the coating layer because Al atom% of the lower layer sequentially increases from the surface of the tool base toward the upper layer, but the upper layer has (100) orientation. For this reason, in high-speed and high-feed machining, the possibility of insufficient wear resistance cannot be denied.

  Therefore, the present invention provides excellent toughness and excellent chipping resistance and wear resistance over a long period of use even when subjected to high-speed and high-feeding such as carbon steel, cast iron and alloy steel. The object is to provide a coated tool.

We have a hard coating comprising at least a composite nitride or composite carbonitride of Ti and Al (hereinafter sometimes referred to as “(Ti _1-x Al _x ) (C _y N _1-y )”). As a result of intensive studies to improve the chipping resistance and wear resistance of the coated tool in which the layer was formed, the following knowledge was obtained.

First, the present inventors have examined chipping resistance and wear resistance when the crystal orientation is changed in a hard coating layer made of (Ti _1-x Al _x ) (C _y N _1-y ). , (Ti _1-x Al _x ) (C _y N _1-y ) oriented in the normal direction of the {100} plane is excellent in chipping resistance, while (Ti _1-x Al _x ) is oriented in the normal direction of the {111} plane (Ti _It has been found that the _1-x Al _x ) (C _y N _1-y ) layer is excellent in wear resistance.
On the other hand, chipping resistance is required for the cutting edge ridge line portion (cutting edge ridge line portion) in the coated tool, and wear resistance is required for portions other than the cutting edge ridge line portion.
Therefore, a (Ti _1-x Al _x ) (C _y N _1-y ) layer oriented in the normal direction of the {100} plane is provided on the cutting edge ridge, and the {111} plane other than the cutting edge ridge normal by providing orientation _{(Ti 1-x Al x)} (C y N 1-y) layer in a direction, it is possible to achieve both chipping resistance and wear resistance even speed and high feed machining of And gained knowledge.

In order to realize the above knowledge, a (Ti _1-x Al _x ) (C _y N _1-y ) layer oriented in the normal direction of the {100} plane is provided by CVD, and {111 } plane normal direction to the orientation of the _{(Ti 1-x Al x)} (C y N 1-y) layer is provided, by carrying out blasting only cutting edge line portion, the actinomycetes direction of {100} plane It has been found that the oriented (Ti _1-x Al _x ) (C _y N _1-y ) layer may be exposed.

Furthermore, when smoothed by blasting _{(Ti 1-x Al x)} (C y N 1-y) layer of the coated tool surface, and finding also together be welding resistance are improved.

The present invention has been made based on the above findings,
“(1) In a surface-coated cutting tool having a hard coating layer 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 is composed of a composite carbonitride layer of Ti and Al having a cubic structure, and the average composition is
Composition formula: (Ti _1-x Al _x ) (C _y N _1-y )
In this case, the Al content ratio x and the C content ratio y (where x and y are atomic ratios) satisfy 0.70 ≦ x ≦ 0.95 and 0 ≦ y <0.005, respectively. ,
(B) The composite carbonitride layer is composed of an upper layer and a lower layer,
The upper layer analyzes the crystal orientation of each crystal grain from the longitudinal cross-sectional direction of the composite carbonitride layer of Ti and Al using an electron beam backscattering diffractometer, and the normal direction of the substrate surface When the inclination angle formed by the normal line of the {111} plane, which is the crystal plane of the crystal grain, is measured, an inclination angle in the range of 0 to 45 degrees with respect to the normal direction is set to 0. When the frequency existing in each section is counted by dividing every 25 degrees pitch, the highest peak exists in the inclination angle section in the range of 2 to 12 degrees, and it exists in the range of 2 to 12 degrees. The sum of the frequencies to be displayed indicates a ratio of 45% or more of the total frequencies in the tilt angle frequency distribution,
The lower layer analyzes the crystal orientation of each crystal grain using an electron beam backscattering diffractometer from the longitudinal cross-sectional direction of the composite carbonitride layer of Ti and Al, and the normal direction of the substrate surface When the inclination angle formed by the normal line of the {100} plane, which is the crystal plane of the crystal grain, is measured, an inclination angle in the range of 0 to 45 degrees with respect to the normal direction is set to 0. When the frequency existing in each section is counted by dividing every 25 degrees pitch, the highest peak exists in the inclination angle section in the range of 2 to 12 degrees, and it exists in the range of 2 to 12 degrees. The sum of the frequencies to be displayed indicates a ratio of 45% or more of the total frequencies in the tilt angle frequency distribution,
(C) The average film thicknesses of the upper layer and the lower layer are both 0.5 to 10 μm,
(D) the lower layer is exposed at the cutting edge ridge line portion;
A surface-coated cutting tool characterized by
(2) The surface cutting tool according to (1), wherein an exposed width of the lower layer in a direction perpendicular to the tool thickness direction is more than 0.01 mm and less than 0.5 mm.
(3) The surface-coated cutting tool according to (1) or (2), wherein an average film thickness of the upper layer is thinner than an average film thickness of the lower layer.
(4) The surface according to any one of (1) to (3), wherein the upper layer and the lower layer have a crystal grain size of 100 to 3000 nm and a crystal grain size aspect ratio of 2 to 10. Coated cutting tool.
(5) The surface-coated cutting tool according to any one of (1) to (4), wherein the surface roughness (Ra) of the portion where the lower layer is exposed is less than 0.5 μm. "
It is.

  The present invention has a remarkable effect that both chipping resistance and wear resistance can be achieved at a high level, and the tool life can be extended even in high-speed high-feed machining.

1-a and 1-b show {100} planes and {100} planes which are crystal planes of crystal grains in the (Ti _1-x Al _x ) (C _y N _1-y ) layer constituting the hard coating layer. It is a schematic explanatory drawing of the inclination angle which the normal line of a surface makes with respect to the normal line of a base surface. FIG. 2A and FIG. 2B show {111} planes and {111} planes that are crystal planes of crystal grains in the (Ti _1-x Al _x ) (C _y N _1-y ) layer constituting the hard coating layer. It is a schematic explanatory drawing of the inclination angle which the normal line of a surface makes with respect to the normal line of a base surface. It is an example of the graph of the inclination angle number distribution of the {100} plane measured about the lower layer of this invention coated tool. It is an example of the graph of the inclination angle number distribution of the {111} plane measured about the upper layer of this invention coated tool. It is a thickness direction cross-section schematic diagram of the hard coating layer of the coating tool of this invention.

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

Composite carbonitride layer of Ti and _{Al ((Ti 1-x Al} x) (C y N 1-y)) the average composition the composite carbonitride layer of the composition _{formula: (Ti 1-x Al x} ) ( C _y N _1-y ), the average content ratio x in the total amount of Ti and Al in Al and the average content ratio y in the total amount of C and N in C (where x and y are In either case, the atomic ratio) controls the composition so as to satisfy 0.70 ≦ x ≦ 0.95 and 0 ≦ y <0.005, respectively.
The reason is that if the average content ratio x of Al is less than 0.70, the (Ti _1-x Al _x ) (C _y N _1-y ) layer is inferior in oxidation resistance, and high-speed, high-feed such as alloy steel When it is used, the wear resistance is not sufficient. On the other hand, when the average content ratio x of Al is larger than 0.95, the amount of hexagonal crystals inferior in hardness increases and the hardness decreases, so that the wear resistance decreases. Therefore, the average content ratio x of Al was determined as 0.70 ≦ x ≦ 0.95.
Further, when the average content ratio y of the C component contained in the (Ti _1-x Al _x ) (C _y N _1-y ) layer is a minute amount in the range of 0 ≦ y <0.005, the lubricity is improved. alleviate the impact during cutting by chipping resistance of the resulting _{(Ti 1-x Al x)} (C y N 1-y) layer, chipping resistance is improved. On the other hand, if the average content ratio y of the C component departs from the range of 0 ≦ y <0.005, the toughness of the (Ti _1-x Al _x ) (C _y N _1-y ) layer is reduced, so chipping resistance, It is not preferable because the fracture resistance is lowered. Therefore, the average content ratio y of C was determined as 0 ≦ y <0.005.
In addition, the content rate of C excludes the inevitable content rate of C contained without intentionally using a gas containing C as a gas raw material, and is a value obtained by subtracting the inevitable content rate of C. Was determined as y.

Composite carbonitride layer of Ti and _{Al ((Ti 1-x Al} x) (C y N 1-y)) lower layer and the composite carbonitride layer of _{((Ti 1-x Al x} ) (C y N 1 _-Y )) For the lower layer, the crystal orientation of each crystal grain is analyzed from the longitudinal section direction using an electron beam backscattering diffractometer (hereinafter referred to as EBSD), and the normal of the substrate surface (cross-section polished surface) When the inclination angle (see FIGS. 1A and 1B) formed by the normal line of the {100} plane that is the crystal plane of the crystal grain is measured with respect to the direction perpendicular to the substrate surface in FIG. When the inclination angle within the range of 0 to 45 degrees with respect to the normal direction is divided into pitches of 0.25 degrees and the frequencies existing in each section are counted, the range of 2 to 12 degrees is obtained. The highest peak exists in the inclination angle section of the above, and the total of the frequencies existing in the range of 2 to 12 degrees However, the hard coating layer composed of the composite carbonitride layer of Ti and Al maintained a cubic structure if the gradient angle distribution form is 45% or more of the entire frequency in the gradient angle distribution. It has high hardness as it is, and the toughness is improved by the inclined angle number distribution form.
When analyzing the crystal orientation of individual crystal grains using EBSD, a crystal plane having an inclination angle larger than 12 degrees with respect to the normal of the substrate surface cannot be regarded as being {100} oriented, and the hardness Since the range where the {100} orientation is strong and the hardness is not lowered is 0 to 12 degrees, the range of the inclination angle section for obtaining the power by measurement is set to 0 to 12 degrees.

  Here, if the average layer thickness of the lower layer is less than 0.5 μm, sufficient chipping resistance over a long period of time cannot be ensured. On the other hand, if the average layer thickness exceeds 10 μm, high heat generation occurs. Since it becomes easy to cause thermoplastic deformation by high-speed interrupted cutting and this causes uneven wear, the average layer thickness is determined to be 0.5 to 10 μm.

For the upper layer upper layer of the composite carbonitride layer of Ti and Al ((Ti _1-x Al _x ) (C _y N _1-y )), the same method and treatment as the lower layer using EBSD, The inclination angle (see FIGS. 2-a and 2-b) formed by the normal of the {111} plane is measured, and the highest peak exists in the inclination angle section within the range of 0 to 12 degrees, and the above 0 to 12 degrees. Ti and Al composite nitride or composite carbonitride layer if the total number of frequencies existing in the range of is an inclination angle number distribution form with a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution The hard coating layer made of is excellent in chipping resistance with high hardness, and the adhesion between the hard coating layer and the substrate is dramatically improved by the inclined angle number distribution form.
When analyzing the crystal orientation of each crystal grain using EBSD, a crystal plane with an inclination angle larger than 12 degrees with respect to the normal of the substrate surface cannot be regarded as being {111} oriented, and the hardness Since the range where the {111} orientation is strong and the hardness does not decrease is from 0 to 12 degrees, the range of the inclination angle section for obtaining the frequency by measurement was set to 0 to 12 degrees.

Here, if the average layer thickness of the upper layer is less than 0.5 μm, sufficient wear resistance over a long period of time cannot be ensured. On the other hand, if the average layer thickness exceeds 10 μm, high heat generation occurs. The accompanying high-speed high-feed processing makes it easier to cause thermoplastic deformation, which causes uneven wear, so the average layer thickness was determined to be 0.5 to 10 μm.
The average layer thickness of the upper layer is preferably thinner than the average layer thickness of the lower layer. The reason is that the chipping resistance of the cutting edge ridge line portion is further improved when the average layer thickness of the lower layer is thicker.

Exposing the lower layer of the cutting edge ridge line In the present invention, the cutting edge ridge line part is an area where the straight line intersects when the rake face and the flank face are approximated by straight lines, and the upper layer is removed, As shown in FIG. 5, the lower layer is exposed with a length of la. The exposed width of the lower layer in the direction perpendicular to the tool thickness direction is preferably more than 0.01 mm and less than 0.5 mm. The reason is that if it is 0.01 mm or less, the exposed width may be insufficient and an improvement in chipping resistance may not be expected. If it is 0.5 mm or more, the exposed width may increase and the wear resistance may be insufficient. This is possible.
Moreover, it is preferable that the surface roughness (Ra) of a cutting edge ridgeline part is less than 0.5 micrometer. The reason is that the welding resistance is further improved when the thickness is less than 0.5 μm.
The surface roughness was measured using a laser surface roughness measuring instrument in accordance with JIS B0601: 2001 at a cutoff value of 0.08 mm, a reference length of 0.8 mm, and a scanning speed of 0.1 mm / second. Value.

Crystal grain size and aspect ratio of upper layer and lower layer The crystal grain size of the upper layer and lower layer is preferably 100 to 3000 nm, and the crystal grain size aspect ratio is preferably 2 to 10. The reason is that if the crystal grain size is less than 100 nm, the effect of suppressing grain boundary slip may not be sufficient, and if it exceeds 3000 nm, the distortion in the layer may increase and the hardness may decrease. .
Also, if the crystal grain size aspect ratio is less than 2, a sufficient columnar structure is not obtained, so that equiaxed crystals with a small aspect ratio may fall off, and sufficient wear resistance can be exhibited. There is no time. On the other hand, if it exceeds 10, the strength of the crystal grains themselves cannot be maintained, and the chipping resistance may be lowered.
Here, the crystal grain size and the aspect ratio are obtained by observing a cross section (longitudinal cross section) in the thickness direction of the upper layer and the lower layer with a SEM in a range including a width of 100 μm and a height including the entire layers. The longest particle diameter is the major axis, the maximum length in the direction perpendicular to the major axis is the crystal grain size, and the average value in the observation range of the value obtained by dividing the major axis by the crystal grain size.

  In order to improve the adhesion between the lower layer and the substrate interface under the lower layer, for example, a known AlTiCN layer in which the Al content is gradually changed from the substrate side to the surface side as necessary, An underlayer such as a TiN layer or a TiCN layer may be provided.

Manufacturing method of exposed part of upper layer, lower layer and cutting edge ridge line part The manufacturing method of the present invention is roughly as follows.
1. A cemented carbide substrate is manufactured by a normal manufacturing method.
2. Next, a base layer is formed on the cemented carbide substrate as necessary.
3. Subsequently, a two-stage film formation is performed using a normal CVD apparatus. At that time, the orientation is changed by changing NH ₃ / (TiCl ₄ + AlCl ₃ ).
3-1. First stage deposition (lower layer deposition)
For example, reaction gas composition (volume%)
_{TiCl 4 0.1~0.8%, AlCl 3 0.5~1.5} %, NH 3 0.8~4.5%, C 2 H 4 0~1%, N 2 0~10.0% , Ar 0-10%, remaining H ₂
Reaction atmosphere temperature: 700 to 900 ° C.
Reaction atmosphere pressure: 2 to 5 kPa,
Is satisfied under the conditions of 0.70 ≦ x ≦ 0.95 and 0 ≦ y <0.005 (where x and y are atomic ratios), and the normal direction of the substrate surface In the inclination angle number distribution in which the inclination angle formed by the normal of the {100} plane is measured, the highest peak is present in the inclination angle section within the range of 2 to 12 degrees, and within the range of 2 to 12 degrees. A hard coating layer (lower layer) composed of a (Ti _1-x Al _x ) (C _y N _1-y ) layer having a cubic structure according to the present invention having a tilt angle number distribution ratio of 45% or more is formed. can do.
3-2. Second stage deposition (upper layer deposition)
For example, reaction gas composition (volume%)
_{TiCl 4 0.1~0.8%, AlCl 3 0.5~1.5} %, NH 3 0.8~4.5%, C 2 H 4 0~1%, N 2 0~10.0% , Ar 0-10%, remaining H ₂
Reaction atmosphere temperature: 700 to 900 ° C.
Reaction atmosphere pressure: 2 to 5 kPa,
Is satisfied under the conditions of 0.70 ≦ x ≦ 0.95 and 0 ≦ y <0.005 (where x and y are atomic ratios), and the normal direction of the substrate surface In the inclination angle distribution in which the inclination angle formed by the normal of the {111} plane is measured, the highest peak is present in the inclination angle section within the range of 2 to 12 degrees, and within the range of 2 to 12 degrees. A hard coating layer (upper layer) composed of a (Ti _1-x Al _x ) (C _y N _1-y ) layer having a cubic structure according to the present invention having a tilt angle number distribution ratio of 45% or more is formed. can do.
4). Exposure of the lower layer at the cutting edge ridge line portion There are various methods for removing the upper layer of the cutting edge ridge line portion. For example, a method by wet blasting using Al ₂ O ₃ is desirable.

  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.

Next, a normal CVD apparatus is used on the surfaces of these tool bases A to C, and first, under the conditions shown in Table 2, the lower layer has a predetermined composition (Ti _1-x Al _x ) (C after depositing form _y N _1-y) layer to a target layer thickness, also in the conditions shown in Table 2 having a predetermined composition is an upper layer _{(Ti 1-x Al x)} (C y N 1- _y ) layer is formed, and then the upper layer of the cutting edge ridge is removed by wet blasting using Al ₂ O ₃ under the conditions shown in Table 5, and the coated tool of the present invention shown in Table 6 1-10 were manufactured.
In addition, about this invention coated tool 8-10, the base layer shown in Table 6 was formed on the formation conditions shown in Table 4.

Further, for the purpose of comparison, (Ti _1-x Al _x ) (C _y N _1-y ) of the comparative example is also used on the surfaces of the tool bases A to C under the conditions shown in Table 3 using a normal CVD apparatus. ) The layer was formed by vapor deposition with the target layer thickness, and then the upper layer of the cutting edge ridge was removed by the wet blasting method using Al ₂ O ₃ under the conditions shown in Table 5, and the comparison shown in Table 7 was made. Coated tools 1-10 were produced. In Table 7, “-” in the “width of the cutting edge ridge line portion (mm)” column indicates that the lower layer is not exposed in the cutting edge ridge line portion.
Moreover, about this invention coated tool 8-10, the base layer shown in Table 7 was formed on the formation conditions shown in Table 4.

The cross-section of each constituent layer of the invention-coated tools 1 to 10 and the comparative example-coated tools 1 to 10 is measured using a scanning electron microscope, and the average layer thickness is measured by averaging the five layer thicknesses within the observation field of view. As a result, the average layer thickness substantially the same as the target average layer thickness shown in Tables 6 and 7 was obtained.
Next, with respect to the hard coating layers of the above-mentioned coated tools 1 to 10 of the present invention, the average Al content ratio x, the average C content ratio y of the hard coating layer, and the inclination formed by the normal of the {100} plane with respect to the normal direction of the substrate surface The ratio (α) of the frequency existing in the range of 2 to 12 degrees in the tilt angle number distribution for the angle, and the tilt angle number for the tilt angle formed by the normal of the {111} plane with respect to the normal direction of the substrate surface The ratio (β) of the frequency existing in the range of 2 to 12 degrees in the distribution was measured.

The specific measuring methods for each of the above are as follows.
The average Al content ratio x and the average C content ratio y of the hard coating layer were determined by secondary ion mass spectrometry (SIMS): Secondary-Ion-Mass-Spectroscope. 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 Al content ratio x and the average C content ratio y indicate average values in the depth direction.

In addition, regarding the inclination angle number distribution of the hard coating layer, the column of the field emission scanning electron microscope with the cross section of the hard coating layer made of a composite carbonitride layer of Ti and Al having a cubic structure as a polished surface Each crystal grain having a cubic crystal lattice existing in the measurement range of the cross-sectional polished surface is irradiated with an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees on the polished surface with an irradiation current of 1 nA. Irradiate and use an electron backscatter diffraction imaging apparatus, the normal surface of the substrate surface (perpendicular to the substrate surface on the cross-section polished surface) at an interval of 0.1 μm / step with respect to the hard substrate over a length of 100 μm in the horizontal direction from the tool substrate. The tilt angle formed by the normal lines of the {100} plane and the {111} plane, which are crystal planes of the crystal grains, and, based on the measurement result, 0 of the measured tilt angles. Measurements in the range of ~ 45 degrees By dividing the inclination angle into pitches of 0.25 degrees and counting the frequencies existing in each section, the ratios (α) and (β) of the frequencies existing in the range of 2 to 12 degrees are obtained. It was.
FIGS. 3 and 4 show examples of the distribution graph of the inclination angle numbers of the {100} plane and {111} plane measured for the coated tool of the present invention.

Subsequently, also about the comparative example coated tools 1-10, similarly to this invention coated tools 1-10, the average Al content rate x of the hard coating layer, the average C content rate y, {100} with respect to the normal direction of the substrate surface The ratios (α) and (β) of the frequencies existing in the range of 2 to 12 degrees in the tilt angle number distribution with respect to the tilt angle formed by the normal of the surface and the {111} plane were measured.
Tables 6 and 7 show the results.

Next, for the present invention coated tools 1 to 10 and comparative example coated tools 1 to 10 in a state where all of the various coated tools are clamped to a tool steel cutter tip portion having a cutter diameter of 125 mm by a fixing jig, A dry high-speed face mill, which is a kind of high-speed high-feed cutting of alloy steel, and a center-cut cutting test shown below were performed, and the flank wear width of the cutting blade was measured. The life criterion was a flank wear width of 0.20 mm.
Work material: Block material of JIS / SCM440 width 100mm, length 400mm
Rotational speed: 943 min ⁻¹ ,
Cutting speed: 380 m / min,
Cutting depth: 1.5 mm,
Single blade feed rate: 0.4 mm / tooth,
Cutting time: 5 minutes Table 8 shows the results of the cutting test. Moreover, regarding the comparative coated tool, the tool that reached the end of its life after the cutting time of 5 minutes or less described the cutting time that reached the end of the life.

From the results shown in Table 6-8, the present invention coated tool _{1-10, (Ti 1-x Al x} ) (C y N 1-y) layer of the cubic structure is deposited, an upper layer and a lower layer Consists of
The upper layer analyzes the crystal orientation of each crystal grain from the longitudinal cross-sectional direction of the composite carbonitride layer of Ti and Al using an electron beam backscattering diffractometer, and the crystal with respect to the normal direction of the substrate surface When the inclination angle formed by the normal of the {111} plane, which is the crystal plane of the grain, is measured, the inclination angle within the range of 0 to 45 degrees with respect to the normal direction is 0.25 degrees. When the frequencies existing in each section are tabulated for each pitch, the highest peak exists in the inclination angle section in the range of 2 to 12 degrees and the frequency in the range of 2 to 12 degrees Indicates a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution,
The lower layer analyzes the crystal orientation of individual crystal grains from the longitudinal cross-sectional direction of the composite carbonitride layer of Ti and Al using an electron beam backscattering diffractometer, and the crystal with respect to the normal direction of the substrate surface When the inclination angle formed by the normal of the {100} plane which is the crystal plane of the grain is measured, the inclination angle within the range of 0 to 45 degrees with respect to the normal direction is 0.25 degrees among the inclination angles. When the frequencies existing in each section are tabulated for each pitch, the highest peak exists in the inclination angle section in the range of 2 to 12 degrees and the frequency in the range of 2 to 12 degrees Indicates a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution,
The average film thickness of the entire flank of the upper layer and the lower layer is both 0.5 to 10 μm,
Furthermore, since the lower layer is exposed at the edge portion of the cutting edge, it exhibits excellent chipping resistance and wear resistance in high-speed high-feed cutting of alloy steel.
On the other hand, for the comparative coated tools 1 to 10 that do not satisfy even one of the invention-specific matters of the present invention, all of the hard coating layers are not only damaged abnormally such as chipping, chipping, peeling, etc. It is clear that the service life is reached in a short time.

As described above, the coated tool of the present invention can be used as a coated tool for various work materials as well as high-speed high-feed cutting of alloy steel, and has excellent chipping resistance over a long period of use. Since it exhibits wear resistance, it can satisfactorily meet the demands for higher performance of cutting devices, labor saving and energy saving of cutting, and cost reduction.

Claims (5)

In a surface-coated cutting tool having a hard coating layer 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 is composed of a composite carbonitride layer of Ti and Al having a cubic structure, and the average composition is
Composition formula: (Ti _1-x Al _x ) (C _y N _1-y )
In this case, the Al content ratio x and the C content ratio y (where x and y are atomic ratios) satisfy 0.70 ≦ x ≦ 0.95 and 0 ≦ y <0.005, respectively. ,
(B) The composite carbonitride layer is composed of an upper layer and a lower layer,
The upper layer analyzes the crystal orientation of each crystal grain from the longitudinal cross-sectional direction of the composite carbonitride layer of Ti and Al using an electron beam backscattering diffractometer, and the normal direction of the substrate surface When the inclination angle formed by the normal line of the {111} plane, which is the crystal plane of the crystal grain, is measured, an inclination angle in the range of 0 to 45 degrees with respect to the normal direction is set to 0. When the frequency existing in each section is counted by dividing every 25 degrees pitch, the highest peak exists in the inclination angle section in the range of 2 to 12 degrees, and it exists in the range of 2 to 12 degrees. The sum of the frequencies to be displayed indicates a ratio of 45% or more of the total frequencies in the tilt angle frequency distribution,
The lower layer analyzes the crystal orientation of each crystal grain using an electron beam backscattering diffractometer from the longitudinal cross-sectional direction of the composite carbonitride layer of Ti and Al, and the normal direction of the substrate surface When the inclination angle formed by the normal line of the {100} plane, which is the crystal plane of the crystal grain, is measured, an inclination angle in the range of 0 to 45 degrees with respect to the normal direction is set to 0. When the frequency existing in each section is counted by dividing every 25 degrees pitch, the highest peak exists in the inclination angle section in the range of 2 to 12 degrees, and it exists in the range of 2 to 12 degrees. The sum of the frequencies to be displayed indicates a ratio of 45% or more of the total frequencies in the tilt angle frequency distribution,
(C) The average film thicknesses of the upper layer and the lower layer are both 0.5 to 10 μm,
(D) the lower layer is exposed at the cutting edge ridge line portion;
A surface-coated cutting tool characterized by   The surface cutting tool according to claim 1, wherein an exposed width of the lower layer in a direction perpendicular to the tool thickness direction is more than 0.01 mm and less than 0.5 mm. The surface-coated cutting tool according to claim 1, wherein an average film thickness of the upper layer is thinner than an average film thickness of the lower layer. The surface-coated cutting tool according to any one of claims 1 to 3, wherein the upper layer and the lower layer have a crystal grain size of 100 to 3000 nm and a crystal grain size aspect ratio of 2 to 10. . The surface-coated cutting tool according to any one of claims 1 to 4, wherein a surface roughness (Ra) of a portion where the lower layer is exposed is less than 0.5 µm.