JP2021137935A - Surface coating cutting tool - Google Patents

Abstract

To provide a coating tool having chipping resistance and wear resistance even in high-speed continuous cutting processing of alloy steel, cast iron or the like.SOLUTION: In a coating tool, a coating layer (Ti1-xAlx)(CyN1-y) of a base body surface has crystal grains having cubic crystal structures of 70 area% or larger, and an average composition is 0.60≤xavg≤0.95, 0.000≤yavg≤0.010. In each of the crystal grains, when setting a range which is surrounded by a curved line separated from a grain boundary by 25 nm into a grain as a region α, setting a range surrounded by the curved line and the grain boundary as a region β, setting average values of x, y in all the regions α as xαavg, yαavg, forming a measurement region which is divided at 50 nm intervals over entire regions of the adjacent regions β, and setting average values of x, y as xβavg, yβavg at the respective measurement regions, a total sum of areas satisfying 0.10≤xβavg≤xαavg-0.10, yαavg+0.010≤yβavg≤0.680 is 5.0 to 20.0 area% with respect to a total area of the region β.SELECTED DRAWING: Figure 1

Description

In particular, the present invention exhibits excellent cutting performance over a long period of use because the hard coating layer has excellent chipping resistance and abrasion resistance even in high-speed intermittent cutting of alloy steel, cast iron, etc. It relates to a surface coating cutting tool (hereinafter, may be referred to as a coating tool).

Conventionally, there is a coating tool in which a Ti—Al-based composite carbonitride layer is coated and formed as a hard coating layer on the surface of a tool substrate such as a tungsten carbide (hereinafter referred to as WC) -based cemented carbide by a vapor deposition method. These are known to exhibit excellent wear resistance.
However, although the conventional covering tool coated with the Ti-Al-based composite carbonitride layer has relatively excellent wear resistance, abnormalities such as chipping when used under severe cutting conditions such as high-speed intermittent cutting. Since wear is likely to occur, various proposals have been made for improving the hard coating layer.

For example, Patent Document 1 discloses a coating layer in which amorphous carbon exists around nanocrystal grains of TiAlCN deposited on a base material, and this coating layer has excellent lubricity and adheres to the base material. It is stated that the sex is good.

Further, for example, Patent Document 2 describes a hard film having nanocrystal grains containing carbon, wherein the hard film contains Al and at least one other metal component (Me1, Me2) and carbon and at least one element (Me1, Me2). It has E1, E2), and its composition is
_{(Al x Me1 y Me2 z)} C u E1 v E2 w
here,
Me1, Me2: Metal element x> 0.4, x + y + z = 1, y ≧ 0, z ≧ 0
0 <u <1, u + v + w = 1, v ≧ 0, w ≧ 0
And
A hard film characterized in that the carbon concentration at the grain boundaries is higher than the carbon concentration in the nanocrystal grains is disclosed, and it is described that this hard film has excellent lubricity and is used for cutting tools.

Further, for example, Patent Document 3 describes a coated article from a metal, cemented carbide, cermet or ceramics coated with a single-layer or multi-layer system, wherein the layer system is at least one hard material composite. It has a layer, the composite layer contains cubic TiAlCN and hexagonal AlN as the main phase, and the cubic TiAlCN has a crystallite size of ≧ 0.1 μm Ti _1-x Al _{x Cy.} N _z (here, x> 0.75, y = 0 to 0.25, and z = 0.75 to 1), and the amorphous carbon is 0. A coating for cutting tools is described, which is characterized by being contained in a mass ratio of 01% to 20%.

U.S. Patent Publication 2003/0143402 European Patent Publication No. 1574594 Japanese Patent Application Laid-Open No. 2013-510946

In recent years, there has been a strong demand for labor saving and energy saving in cutting, and along with this, cutting tends to be faster and more efficient, and the hard coating of covering tools has even more chipping resistance and resistance to chipping. Abnormal damage resistance such as chipping resistance and peeling resistance is required, and excellent wear resistance is required over a long period of use.

However, when the covering tools described in the above publications are subjected to high-speed intermittent cutting of alloy steel, cast iron, etc., abnormal damage such as thermal cracks occurs, and chipping starting from the damage is likely to occur, which is satisfactory. It cannot be said that the cutting performance is exhibited.

Therefore, the present invention has been made in view of such a situation, and in particular, even in high-speed intermittent cutting of alloy steel, cast iron, etc., the hard coating layer has excellent chipping resistance and wear resistance. It is an object of the present invention to provide a covering tool that exhibits excellent cutting performance over a long period of use.

The present inventor has diligently studied to improve the chipping resistance and abrasion resistance of a coating tool containing a composite carbonitride layer of Ti and Al (hereinafter, sometimes referred to as "TiAlCN layer") as a hard coating layer. Was piled up.

As a result, when a region having a high C content ratio and a low Al content ratio exists at a predetermined ratio in the vicinity of the grain boundaries of the crystal grains constituting the TiAlCN layer, the hardness of the TiAlCN layer is improved and the abrasion resistance is improved. It was found that the TiAlCN layer was improved and the chipping resistance was improved by applying compressive stress to the TiAlCN layer.

The present invention is based on this finding and is as follows.
"(1) A surface-coated cutting tool having a tool substrate and a hard coating layer including a composite carbonitride layer of Ti and Al on the surface of the tool substrate.
(A) The composite carbonitride layer is composed of crystal grains, and the crystal grains having a NaCl-type face-centered cubic structure are 70 area% or more.
(B) The composition of the composite carbonitride layer is as follows.
Composition formula: When expressed by _{(Ti 1-x} Al _x ) ( _Cy N _{1-y)
The average value x avg} of the content ratio x of Al in the total amount of Al and Ti and _{the average value y avg} of the content ratio of C in the total amount of C and N are 0.60 ≤ x _avg ≤ 0.95, respectively. , 0.000 ≤ y _avg ≤ 0.010,
(C) In each crystal grain having a NaCl-type face-centered cubic structure, a range surrounded by a curve separated from the crystal grain boundary by 25 nm in the crystal grain is surrounded by a region α, the curve and the crystal grain boundary. Let the area β be the area β
The average values of x and y in the region α were obtained for each crystal grain, and the averaged values were defined as xα _avg and yα _avg , respectively.
In the region β, measurement regions divided at intervals of 50 nm along the grain boundaries are provided over the entire region of adjacent ones, and the average values of x and y obtained for each measurement region are xβ _avg and yβ _{avg, respectively.} When
_{Relationship: 0.10 ≦ xβ avg ≦ xα avg} -0.10, 5 total area of the measurement region satisfying the _{yα avg + 0.010 ≦ yβ avg ≦} 0.680 is the total area of the region β .0 to 20.0 area% present,
A surface coating cutting tool characterized by.
(2) The crystal grains having a NaCl-type face-centered cubic structure are characterized in that the average particle width W is 0.10 to 2.00 μm and the average aspect ratio A is 2.0 to 10.0. The surface-coated cutting tool according to (1). "

The surface-coated cutting tool of the present invention has excellent cutting performance over a long period of time because the hard coating layer has excellent chipping resistance and abrasion resistance even in high-speed intermittent cutting of alloy steel, cast iron, etc. Demonstrate.

It is a schematic diagram which shows the region α and region β.

The present invention will be described in detail below. In the present specification and the claims, when the numerical range is expressed by "A to B" (both A and B are numerical values), the range includes the upper limit value (B) and the lower limit value (A). The unit of the upper limit value (B) and the lower limit value (A) is the same.

Area ratio of crystal grains having a NaCl-type face-centered cubic structure in the TiAlCN layer:
The TiAlCN layer is composed of crystal grains, and in these crystal grains, the area ratio of the crystal grains having a NaCl-type face-centered cubic structure is the cross section in the layer thickness direction (the cross section perpendicular to the surface of the tool substrate, which is also called the vertical cross section). It is preferably 70 area% or more. The reason is that if it is 70 area% or more, it can surely contribute to the achievement of the object of the present invention. Here, 70 area% or more means that the upper limit may be 100 area% (all crystal grains have a NaCl-type face-centered cubic structure). This area ratio is more preferably 80 area% or more.
For the area ratio in which the crystal grains have a NaCl-type face-centered cubic structure, the results at the time of determining the grain boundaries, which will be described later, are used.

Average composition of TiAlCN layer:
The TiAlCN layer in the present invention is represented by the composition formula: (Ti _1-x Al _x ) ( _Cy N _1-y ).
_{The average x avg} of the Al content ratio (hereinafter referred to as "Al content ratio") x in the total amount of Ti and Al is the C content ratio (hereinafter, "C content ratio") in the total amount of C and N. The average y _avg of y is 0.60 ≤ x _avg ≤ 0.95 and 0.000 ≤ y _avg ≤ 0.010 (however, x, y, x _avg , and y _avg are all atomic ratios). To be satisfied.
The ratio of (Ti _1-x Al _x ) to (C _y N _1-y ) is not particularly limited, but when (Ti _1-x Al _x ) is 1, (C _y N) _{The ratio of 1-y} ) is preferably 0.8 to 1.2. The reason is that if the ratio of ( _Cy N _{1-y ) to (Ti 1-x} Al _x ) is within the above range, the object of the present invention can be surely achieved.
Further, even if the TiAlCN layer contains a trace amount of unavoidable impurities such as O and Cl, the effect of the invention is not impaired.

The reason for defining the range _{of x avg} and y _avg as described above is as follows.
If the average x _avg of the Al content is less than 0.60, the hardness of the TiAlCN layer is inferior, so that the wear resistance is not sufficient when it is subjected to high-speed intermittent cutting of alloy steel, cast iron, etc. If it exceeds 0.95, hexagonal crystal grains are precipitated and the wear resistance is lowered. Therefore, 0.60 ≦ x _avg ≦ 0.95 was set, but more preferably 0.70 ≦ x _avg ≦ 0.90.
The average y- _avg of the C content ratio was set to 0.000 ≦ y- _avg ≦ 0.010 because the hardness can be improved while maintaining the chipping resistance in the above range. Therefore, 0.000 ≦ y _avg ≦ 0.010 is preferable, but 0.006 ≦ y _avg ≦ 0.010 is more preferable.

_{The average x avg} of the Al content ratio of the TiAlCN layer is obtained by irradiating a sample whose vertical cross section has been polished using Auger electron spectroscopy (AES) from the vertical cross section side and in the film thickness direction (tool substrate). It is an average of the analysis results of Auger electrons obtained by performing at least 5 line analyzes over the entire length (in the direction perpendicular to the surface of the).

In addition, the average _yavg of the C content ratio is determined by secondary ion mass spectrometry (SIMS: Secondary Ion Mass Spectrometry). That is, in a sample whose surface has been polished, an ion beam is irradiated from the surface side of the TiAlCN layer to a range of 70 μm × 70 μm, and surface analysis by the ion beam and etching by a sputter ion beam are alternately repeated to form a composition in the depth direction. Make a measurement. First, the average of data obtained by measuring a depth of at least 0.5 μm at a pitch of 0.1 μm or less from a portion of the TiAlCN layer that has penetrated 0.5 μm or more in the depth direction of the layer is obtained. Further, the results of repeated calculations at least at 5 points on the sample surface are averaged and obtained _{as the average yavg} of the C content ratio.

Composition relationship between the region near the grain boundary and the region other than the grain boundary in the crystal grain having a NaCl-type face-centered cubic structure of the TiAlCN layer:
As shown in FIG. 1, in each crystal grain having a NaCl-type face-centered cubic structure, a region α is defined as a range surrounded by a curve 25 nm away from the crystal grain boundary in the crystal grain, and the curve and the crystal grain. The area surrounded by the boundary is defined as the region β.
The average values of x and y in the region α were obtained for each crystal grain, and the averaged values were defined as xα _avg and yα _avg , respectively.
In the region β, measurement regions divided at intervals of 50 nm along the grain boundaries are provided over the entire region of adjacent ones, and the average values of x and y obtained for each measurement region are xβ _avg and yβ _{avg, respectively.} When
_{Relationship: 0.10 ≦ xβ avg ≦ xα avg} -0.10, 5 total area of the measurement region satisfying the _{yα avg + 0.010 ≦ yβ avg ≦} 0.680 is the total area of the region β It is preferably present in an area% of 0 to 20.0.
_{Here, x, y, x avg,} y avg, xα avg, yα avg, xβ avg, yβ avg is an atomic ratio.

The reason is as follows.
xβ _avg> xα _avg -0.10, If it is yα _avg +0.010> yβ _avg, the movement of dislocations is difficult to suppress a small effect of improving the hardness of the TiAlCN layer, the lattice constant of the grain boundary vicinity Since it does not rise, compressive stress is not applied to the TiAlCN layer, and the effect of improving chipping resistance is small. On the other hand, when xβ _avg is less than 0.10 or yβ _avg exceeds 0.680, the high temperature oxidation resistance of the TiAlCN layer is inferior, so that the chipping resistance is lowered. _{Thus, 0.10 ≦ xβ avg ≦ xα avg} -0.10, was _{yα avg + 0.010 ≦ yβ avg ≦} 0.680.
Regarding the area ratio of the region β that satisfies the above relational expression regarding the composition of the region α and the region β, if the ratio existing in the region β is less than 5.0 area%, the hardness improving effect of the TiAlCN layer is obtained. The effect of improving the chipping resistance is small, and if it exceeds 20.0 area%, the high temperature oxidation resistance of the TiAlCN layer is inferior, so that the chipping resistance is lowered. Therefore, the area ratio is preferably 5.0 to 20.0 area%, but more preferably 10.0 to 20.0 area%.

Here, a method for measuring the composition of the region α and the region β will be described.
First, the crystal grain boundaries of the crystal grains constituting the TiAlCN layer are obtained and the crystal grains are specified as follows. That is, using a crystal orientation analyzer attached to a transmission electron microscope (TEM), a surface-polished surface (longitudinal section) perpendicular to the surface of the tool substrate is oriented in the normal direction of the surface-polished surface. On the other hand, while irradiating the electron beam tilted at 0.5 to 1.0 degrees with Precision (year difference motion), the electron beam is scanned at an arbitrary beam diameter and interval, and the electron diffraction pattern is continuously captured, and the individual electron diffraction patterns are captured. Analyze the crystal orientation of the measurement point. The grain boundaries are determined with respect to the observation field of view having a width of 50 μm in the direction parallel to the surface of the tool substrate and a layer thickness (average layer thickness) in the vertical direction.

The acquisition conditions of the electron diffraction pattern used in this measurement are an acceleration voltage of 200 kV, a camera length of 20 cm, a beam size of 2.4 nm, and a measurement step of 5.0 nm. At this time, the measured crystal orientation is obtained by examining the measurement surface discretely, and by representing the region up to the middle between adjacent measurement points with the measurement result, it is obtained as the orientation distribution of the entire measurement surface. be. As a region represented by these measurement points (hereinafter, may be referred to as a pixel), a square shape can be exemplified. If there is an angular difference of 5 degrees or more in crystal orientation between adjacent pixels, or if only one of the adjacent pixels exhibits a NaCl-type face-centered cubic structure, the region in which these pixels are in contact. The side of is the grain boundary. Then, the portion surrounded by the side defined as the grain boundary is defined as one crystal grain. However, pixels that exist independently, such as those with an orientation difference of 5 degrees or more from all adjacent pixels or no measurement point having an adjacent NaCl-type face-centered cubic structure, are not crystal grains and are 2 pixels or more. Are treated as crystal grains. In this way, the grain boundary is determined and the crystal grains are specified.

Next, an observation field containing at least 10 NaCl-type surface-centered cubic structures identified by the above procedure is defined, and energy dispersive X-ray spectroscopy (EDS: Energy Dispersive X) using TEM is used. Surface analysis is performed using −ray Spectrometry) (beam diameter 1 nm). Regarding the region α, the average values of the x and the y were obtained for each crystal grain having the NaCl-type face-centered cubic structure in all the regions α in the observation field of view, and the averages thereof were obtained. Calculated as xα _avg and yα _avg. Then, in all the regions β in the observation field, measurement regions divided at intervals of 50 nm along the grain boundary are provided over the entire regions of adjacent ones, and the average values of x and y are set for each measurement region, respectively. X? _avg, calculated as _{yβ avg, 0.10 ≦ xβ avg ≦} xα avg -0.10, total area of the measurement region satisfying the _{yα avg + 0.010 ≦ yβ avg ≦} 0.680 is in the observation field of view The area ratio to the total area of the region β is calculated.

Average thickness of TiAlCN layer:
The TiAlCN layer of the present invention constitutes a hard coating layer. The average thickness of this TiAlCN layer is preferably 1.0 to 20.0 μm. If the average layer thickness is less than 1.0 μm, the wear resistance over a long period of time may not be sufficiently ensured because the layer thickness is thin. On the other hand, if the average layer thickness exceeds 20.0 μm, the TiAlCN layer Crystal grains are likely to be coarsened, and chipping may be likely to occur. The average layer thickness is more preferably 3.0 to 15.0 μm.

Here, the average thickness of the TiAlCN layer is determined by longitudinally traversing the TiAlCN layer at an arbitrary position by using, for example, a focused ion beam device (FIB: Focused Ion Beam system), a cross section polisher device (CP: Cross section microscope), or the like. A sample for observation is prepared by cutting on a surface (a surface perpendicular to the surface of the tool substrate), and the vertical section thereof is cut at a plurality of locations (for example, 5 locations) using a scanning electron microscope (SEM). It can be obtained by observing and averaging.

Average particle width and average aspect ratio of TiAlCN layer:
In the present invention, the TiAlCN layer has a columnar crystal structure, and the average particle width W in the vertical cross section of the crystal grains in the structure is 0.10 to 2.00 μm, and the average aspect ratio A is 2.0 to 10.0. Is more preferable. The reason is that when the average particle width W is smaller than 0.10 μm, the number of starting points of chipping increases due to the increase in grain boundaries, and the chipping resistance decreases, while the average particle width W is 2.00 μm. This is because the toughness tends to decrease due to the presence of coarsely grown particles. Further, when the average aspect ratio A becomes a granular crystal smaller than 2.0, the interface tends to become a fracture starting point against the shear stress generated on the surface of the hard coating layer during cutting, which may cause chipping. Further, when the average aspect ratio A exceeds 10.0, minute chipping occurs at the cutting edge during cutting, and when the adjacent columnar crystal structure is chipped, the resistance to the shear stress generated on the surface of the hard coating layer. Is likely to become smaller, and the columnar crystal structure is broken, causing damage to proceed at once, which may cause large chipping. Therefore, it is more preferable that the average particle width W of the crystal grains is 0.10 to 2.00 μm and the average aspect ratio A is 2.0 to 10.0.

Next, a method of calculating the average particle width W and the average aspect ratio A of the crystal grains will be described. First, as described above, the grain boundaries are determined to identify the crystal grains. Next, the image processing, certain maximum length H _i, particle width W _i is the maximum length of the tool substrate and the horizontal direction of the tool substrate and the direction perpendicular to the grain i (layer thickness _direction), and area _Find Si. The aspect ratio _{A i} grain i is calculated as _A i ₌ H i / _{W i.} In this way, the area-weighted average is performed by the number 1 based on _{the particle widths W 1 to} W _n (n ≧ 20) of at least 20 or more (i = 1 to 20 or more) crystal grains in the observation field, and the crystal grains are said. The average particle width W of. Further, in the same manner, the aspect ratios A _{1 to An} (n ≧ 20) of the crystal grains are obtained, and the area weighted average is obtained by the equation 2 to obtain the average aspect ratio A of the crystal grains.

Other layers:
As the hard coating layer, the hard coating layer including the TiAlCN layer of the present invention has sufficient chipping resistance and abrasion resistance in high-speed intermittent cutting of alloy steel, cast iron, etc., but separately from the hard coating layer. Ti composed of one or more layers of a carbide layer, a nitride layer, a carbon nitride layer, a carbon oxide layer and a carbon dioxide oxide layer of Ti, and having a total average layer thickness of 0.1 to 20.0 μm. When a lower layer containing a compound (not limited to stoichiometric compound) layer is provided adjacent to the tool substrate and / or at least a layer containing an aluminum oxide (not limited to stoichiometric compound) layer When provided on the TiAlCN layer as an upper layer with a total average layer thickness of 1.0 to 25.0 μm, in combination with the effects of these layers, even more excellent chipping resistance, Abrasion resistance can be exhibited.

Here, if the total average layer thickness of the lower layer is less than 0.1 μm, the effect of the lower layer is not sufficiently exhibited, while if it exceeds 20.0 μm, the crystal grains of the lower layer tend to be coarsened and chipping occurs. It will be easier to do. Further, when the total average layer thickness of the upper layer including the aluminum oxide layer is less than 1.0 μm, the effect of the upper layer is not sufficiently exhibited, while when it exceeds 25.0 μm, the crystal grains of the upper layer tend to be coarsened. , Chipping is likely to occur.

Tool base:
As the tool substrate, any substrate conventionally known as this type of tool substrate can be used as long as it does not hinder the achievement of the object of the present invention. For example, cemented carbide (WC-based cemented carbide, WC, as well as those containing Co and further added with carbonitrides such as Ti, Ta, Nb, etc.), cermet (TiC, It is preferably one of TiN, TiCN and the like as a main component), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide and the like), or a cBN sintered body.

Production method:
The method for forming the TiAlCN layer of the present invention is, for example, as follows. Using the gas group A and the gas group B, which will be described later, the first to nth film formations are performed. The target TiAlCN layer thickness is obtained in the nth film formation. Each film formation consists of a process 1 in which a new film is deposited on the surface to increase the layer thickness, and a process 2 in which the Ti concentration and the C concentration near the grain boundaries are increased. For each film formation, step 1 is carried out for a certain period of time, and then step 2 is carried out for half the time. In the process 2, a new layer is hardly deposited on the surface of the layer formed in the process 1, and the change in the layer thickness is practically negligible.

Examples of the two types of reaction gas compositions are as follows. The gas composition is the sum of the compositions of the gas group A and the gas group B as 100% by volume, and is abbreviated as% below. The gas composition for which the process is not described is the composition range common to the process 1 and the process 2.
Gas group A: NH ₃ : 2.0 to 5.0% (process 1), 0.1 to 0.3% (process 2),
H ₂ : 65-75%
Gas group B: AlCl ₃ : 0.54 to 1.12% (process 1),
0.01-0.05% (process 2),
TiCl ₄ : 0.05 to 0.44%,
N ₂ : 0.0 to 10.0%,
CH ₄ : 0.1 to 5.9%, C ₂ H ₄ : 0.1 to 6.0%,
H ₂ : Residual reaction atmospheric pressure: 4.0 to 5.0 kPa
Reaction atmosphere temperature: 700-850 ° C
Gas supply cycle: 2.00 to 15.00 seconds Gas supply time per cycle: 0.15 to 0.25 seconds Phase difference between supply of gas group A and gas group B: 0.10 to 0.20 seconds

Next, an example will be described.
Here, as a specific example of the coated tool of the present invention, the one applied to the insert cutting tool using the WC-based cemented carbide as the tool base will be described, but it is the case where the other tool as described above is used as the tool base. The same applies to the case where it is applied to a drill or an end mill.

As raw material powders, both WC powder having an average particle size of 1 to 3 [mu] m, TiC powder, TaC powder, NbC powder, _Cr 3 _{C 2} powder, ZrC powder, prepared TiN powder and Co powder, these raw material powders, It was blended to the blending composition shown in Table 1, further added with wax, mixed in a ball mill in acetone for 24 hours, dried under reduced pressure, and then press-molded into a green compact having a predetermined shape at a pressure of 98 MPa to obtain this green compact. Vacuum sintered in a vacuum of 5 Pa at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour, and after sintering, a tool substrate made of WC-based superhard alloy having an insert shape of ISO standard SEEN1203AFSN. Tool bases D to F made of WC-based superhard alloy having insert shapes of A to C and ISO standard CNMG120412 were manufactured, respectively.

Next, a TiAlCN layer is formed on the surfaces of these tool bases A to F by CVD under the film forming conditions shown in Tables 2 and 4, using a CVD apparatus, and the covering tools 1 to 18 of the present invention shown in Table 7 are formed. Got
A1 to I1 and A2 to I2 correspond to the above-mentioned processes 1 and 2, respectively.

In the above process 1, the formation symbols A to I and A1 to I1 indicating the formation conditions shown in Tables 2 and 4, that is, NH ₃ : 2.0 to 5.0% and H ₂ : 65 as the gas group A. ~ 75%, AlCl ₃ : 0.54 to 1.12% _{as gas group B, TiCl 4} : 0.05 to _{0.44%, N 2} : 0.0 to 10.0%, CH ₄ : 0.1 ~ 5.9%, C ₂ H ₄ : _{0.1-6.0%, H 2} : Residual (% is the volume% of the total of gas group A and gas group B), reaction atmosphere pressure: 4. 0 to 5.0 kPa, reaction atmosphere temperature: 700 to 850 ° C., gas supply cycle: 2.00 to 15.00 seconds, gas supply time per cycle: 0.15 to 0.25 seconds, gas group A and gas The phase difference of the supply of group B was set to 0.10 to 0.20 seconds, and film formation was performed by the CVD method for a predetermined time. In the above process 2, the formation symbols A to I and A2 to I2 indicating the formation conditions shown in Tables 2 and 4, that is, NH ₃ : 0.1 to 0.3% and H ₂ : 65 as the gas group A. ~ 75%, AlCl ₃ : 0.01 to _{0.05% as gas group B, TiCl 4} : 0.05 to _{0.44%, N 2} : 0.0 to 10.0%, CH ₄ : 0.1 ~ 5.9%, C ₂ H ₄ : 0.1 to 6.0%, H ₂ : Residual (% is the volume% of the total of gas group A and gas group B), reaction atmosphere pressure: 4. 0 to 5.0 kPa, reaction atmosphere temperature: 700 to 850 ° C., gas supply cycle: 2.00 to 15.00 seconds, gas supply time per cycle: 0.15 to 0.25 seconds, gas group A and gas The phase difference of the supply of group B was set to 0.10 to 0.20 seconds, and the Ti concentration and the C concentration near the grain boundary were increased by the CVD method for a predetermined time.
In the film formation using the formation symbols not noted in Table 2, the film formation time in process 2 was set to half that in process 1.

By forming the TiAlCN layer under the above conditions, the covering tools 1 to 18 of the present invention shown in Table 7 were manufactured. Here, in the covering tools 2, 6, 8, 9, 14, 16 to 18 of the present invention, as shown in Table 6, the lower layer and / or the upper layer was formed under the film forming conditions shown in Table 5.

Further, for comparison, a TiAlCN layer is formed on the surfaces of the tool bases A to F by CVD using the CVD apparatus with the formation symbols a to i indicating the film forming conditions shown in Tables 3 and 4, and the tables are shown. Comparative Examples Covering Tools 1 to 18 shown in No. 7 were obtained. In addition, b1 to i1 and b2 to i2 correspond to the above-mentioned process 1 and process 2, respectively.
Here, in Comparative Examples Covering Tools 2, 6, 8, 9, 14, 16 to 18, as shown in Table 6, the lower layer and / or the upper layer was formed under the film forming conditions shown in Table 5.

Subsequently, for the covering tools 1 to 9 and the comparative covering tools 1 to 9 of the present invention, the various tool substrates A to C (ISO standard SEEN1203AFSN shape) are fixed to the tip of an alloy steel cutter having a cutter diameter of 80 mm. The wet high-speed face milling and center-cut cutting test 1 of the alloy steel shown below was carried out with the tool clamped, and the flank wear width of the cutting edge was measured. Table 8 shows the results of the cutting test 1. It should be noted that the comparative covering tools 1 to 9 have reached the end of their life before the end of the cutting time due to the occurrence of chipping, so the time until the end of the life is shown.

Cutting test 1: Wet high-speed face milling cutter, center cut cutting cutter diameter: 80 mm
Work material: JIS / SCM440 Block material with width 60 mm and length 250 mm Rotation speed: 1393 min ^-1
Cutting speed: 350m / min
Notch: 2.5 mm
Single blade feed amount: 0.25 mm / blade Cutting time: 6 minutes (normal cutting speed is 200 m / min)

Further, with respect to the covering tools 10 to 18 and the comparative covering tools 10 to 18 of the present invention, the various covering tool bases D to F (ISO standard CNMG120412 shape) are all fixed to the tip of the alloy steel cutting tool with a fixing jig. The wet high-speed intermittent cutting test 2 of ductile cast iron shown below was carried out in the state of being screwed, and the flank wear width of the cutting edge was measured. Table 9 shows the results of the cutting test 2. It should be noted that the comparative covering tools 10 to 18 have reached the end of their life before the end of the cutting time due to the occurrence of chipping, so the time until the end of the life is shown.

Cutting test 2: Wet high-speed intermittent cutting Work material: JIS / FCD700 8 equidistant round bars in the length direction Cutting speed: 350 m / min
Notch: 1.5 mm
Feed amount: 0.2 mm / rev
Cutting time: 3 minutes (normal cutting speed is 200 m / min)

From the results shown in Tables 8 and 9, in each of the coating tools 1 to 18 of the present invention, since the hard coating layer has excellent chipping resistance and peeling resistance, high-speed intermittent cutting of alloy steel and cast iron Even when used for processing, chipping does not occur and excellent wear resistance is exhibited for a long period of time. On the other hand, the comparative covering tools 1 to 18 which do not satisfy even one of the matters specified in the covering tool of the present invention cause chipping when used for high-speed intermittent cutting of alloy steel or cast iron. It has reached the end of its useful life in a short time.

As described above, the covering tool of the present invention can also be used as a covering tool for high-speed intermittent cutting other than alloy steel and cast iron, and yet exhibits excellent chipping resistance and abrasion resistance for a long period of time. Therefore, it is possible to fully satisfy the improvement of the performance of the cutting device, the labor saving and the energy saving of the cutting process, and the cost reduction.

Claims (2)

A surface-coated cutting tool having a tool substrate and a hard coating layer containing a composite carbonitride layer of Ti and Al on the surface of the tool substrate.
(A) The composite carbonitride layer is composed of crystal grains, and the crystal grains having a NaCl-type face-centered cubic structure are 70 area% or more.
(B) The composition of the composite carbonitride layer is as follows.
Composition formula: When expressed by _{(Ti 1-x} Al _x ) ( _Cy N _{1-y)
The average value x avg} of the content ratio x of Al in the total amount of Al and Ti and _{the average value y avg} of the content ratio of C in the total amount of C and N are 0.60 ≤ x _avg ≤ 0.95, respectively. , 0.000 ≤ y _avg ≤ 0.010,
(C) In each crystal grain having a NaCl-type face-centered cubic structure, a range surrounded by a curve separated from the crystal grain boundary by 25 nm in the crystal grain is surrounded by a region α, the curve and the crystal grain boundary. Let the area β be the area β
The average values of x and y in the region α were obtained for each crystal grain, and the averaged values were defined as xα _avg and yα _avg , respectively.
In the region β, measurement regions divided at intervals of 50 nm along the grain boundaries are provided over the entire region of adjacent ones, and the average values of x and y obtained for each measurement region are xβ _avg and yβ _{avg, respectively.} When
_{Relationship: 0.10 ≦ xβ avg ≦ xα avg} -0.10, 5 total area of the measurement region satisfying the _{yα avg + 0.010 ≦ yβ avg ≦} 0.680 is the total area of the region β .0 to 20.0 area% present,
A surface coating cutting tool characterized by. According to claim 1, the crystal grains having a NaCl-type face-centered cubic structure have an average particle width W of 0.10 to 2.00 μm and an average aspect ratio A of 2.0 to 10.0. Described surface coating cutting tools.

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