JP6850997B2 - Surface-coated cutting tool with excellent chipping resistance, heat-resistant crack resistance, and oxidation resistance with a hard film layer - Google Patents

Description

The present invention is a high-speed intermittent cutting process in which a shocking load acts on a cutting edge while generating high heat of cast iron or the like, and the hard coating layer has excellent chipping resistance, heat crack resistance, and oxidation resistance. As a result, it relates to a surface-coated cutting tool that exhibits excellent cutting performance over a long period of use.

Conventionally, it is 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 ultrahigh-pressure sintered body. A coated tool in which a Ti—Al-based composite nitride layer is vapor-deposited by a physical vapor deposition method is known as a hard coating layer on the surface of a tool substrate (hereinafter, these may be collectively referred to as a substrate). These are known to exhibit excellent wear resistance.
Here, the conventional coated tool formed by vapor-depositing a Ti—Al-based composite nitride layer has relatively excellent wear resistance, but is liable to cause abnormal wear such as chipping when used under high-speed intermittent cutting conditions. Therefore, various proposals have been made for improving the hard coating layer.

For example, in Patent Document 1, a cubic (Ti _1-X Al _X ) ( _CY N _1-Y ) layer is vapor-deposited as a hard coating layer by a thermal CVD method, and the hard coating layer and a substrate are formed. By having a composition gradient structure in which the Al content ratio in the hard coating layer gradually increases from the interface side with and toward the surface layer side of the hard coating layer, the composition is adjusted (Ti _1-X Al _X ) (Ti 1-X Al X). C Y _{N 1-Y)} actively introducing technology distortion due to the difference in lattice constant is disclosed.
According to this technique, for example, _{when a hard coating layer composed of (Ti 1-X} Al _X ) ( _CY N _1-Y ) layers is used for high-speed intermittent cutting of alloy steel, chipping, chipping, It is said that the occurrence of peeling and the like is suppressed, and excellent wear resistance is exhibited over a long period of use of the surface coating tool.
Further, Patent Documents 2, 3, 4, 5, and 6 describe a composite nitride or composite carbonitride layer of Ti and Al, or Ti, Al, and Me (where Me is Si, Zr, B, V). , A type of element selected from Cr) composite nitride or composite carbonitride layer, or a hard film layer composed of a Cr and Al composite nitride or composite carbonitride layer, in the crystal grains. Regarding the crystal orientation of crystal grains having a NaCl-type face-centered cubic structure, the average orientation difference (GOS value) within each crystal grain analyzed from the longitudinal cross-sectional direction using an electron beam backscattering diffractometer is at a certain level. The technology to be introduced above is disclosed.
According to this technique, _{when a hard coating layer composed of (Ti 1-X} Al _X ) ( _CY N _1-Y ) layers is used for high-speed intermittent cutting of alloy steel, chipping and chipping are suppressed. At the same time, it is said that excellent wear resistance is exhibited over a long period of use of surface coating tools.

Japanese Unexamined Patent Publication No. 2013-212575 JP-A-2015-214015 Japanese Unexamined Patent Publication No. 2016-5863 JP-A-2017-80883 JP-A-2017-80884 Japanese Unexamined Patent Publication No. 2017-47526

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 surface-coated cutting tools are subject to chipping, chipping, peeling, etc. Further suppression, excellent wear resistance is required over a long period of use.
However, the technique described in Patent Document 1 positively distorts due to the difference in lattice constant in order to suppress the occurrence of chipping, chipping, peeling, etc. when the hard coating layer is used for high-speed intermittent cutting of alloy steel. No particular consideration has been given to the effects on chipping resistance, heat crack resistance, and oxidation resistance due to defects in each crystal particle constituting the hard film layer.
Further, the techniques described in Patent Documents 2, 3, 4, 5, and 6 are used to obtain the average intergranular orientation difference (GOS) of crystal grains having a cubic crystal structure of the composite nitride or composite carbonic nitride layer. Although we are paying attention, the average intergranular orientation difference (GOS value) is an evaluation that includes the orientation difference from the target pixel to the pixel far from the target pixel, and special consideration is given to the orientation difference between adjacent pixels. Therefore, it cannot be said that the film has increased toughness of the crystal grains themselves.
Therefore, the present invention exhibits even better chipping resistance, heat-resistant crack resistance, and oxidation resistance even when used for high-speed intermittent cutting of cast iron or the like, which is prone to abnormal damage such as chipping and chipping. At the same time, it is an object of the present invention to provide a covering tool having excellent wear resistance over a long period of use.

As described above, the present inventor has at least Ti and Al from the viewpoint of providing a covering tool that exhibits chipping resistance, heat crack resistance, and oxidation resistance, and also has excellent wear resistance over a long period of use. Chipping resistance of a coating tool formed by depositing a hard coating layer containing a composite nitride layer or a composite carbonitride (hereinafter _{sometimes referred to as "(Ti 1-x} Al _x ) ( _Cy N _1-y)"). As a result of intensive research on the presence or absence of strain and defects due to the difference in crystal orientation in the crystal particles of the hard film layer in order to improve resistance, heat crack resistance, oxidation resistance, and wear resistance. The following new findings were obtained.

That is, the crystal orientation of the crystal grains having the NaCl-type plane-centered cubic structure of _{(Ti 1-x} Al _x ) ( _Cy N _{1-y) is determined in the longitudinal direction (base surface) using an electron backscatter diffraction device.} Analyze from the cross section in the normal direction with respect to), measure the orientation mapping by electron backscatter diffraction, analyze the crystal orientation relationship between each measurement point, and calculate the average local orientation difference (GAM value) of the measured crystal grains. If you ask,
The crystal grains having an intra-crystal local orientation difference average (GAM value) of less than 1 degree are the NaCl-type face-centered cubic structure of _{(Ti 1-x} Al _x ) ( _Cy N _1-y). When the area ratio is 60% or more in a certain crystal grain,
(Ti _1-x Al _x ) ( _Cy N _1-y ) improved chipping resistance, heat crack resistance, oxidation resistance, and abrasion resistance of a coating tool having a hard coating layer including a NaCl-type face-centered cubic structure. It was found that sexual improvement was made.

Therefore, when a coating tool provided with the above-mentioned hard coating layer is used, for example, for high-speed intermittent cutting of cast iron or the like, chipping and thermal cracking are further suppressed, and over a long period of use. It can exhibit excellent wear resistance.

The present invention has been made based on the above findings, and is as follows.
"(1) Surface coating cutting in which a hard coating layer is provided on the surface of a tool substrate composed of either a tungsten carbide-based cemented carbide, a titanium nitride-based cermet, or a cubic boron nitride-based ultrahigh-pressure sintered body. In the tool
(A) The hard coating layer contains at least a composite nitride layer or a composite carbonitride layer of Ti and Al having an average layer thickness of 1.0 to 20.0 μm, and has a composition formula: (Ti _1-x Al _x ). When _{represented by (Cy} N _1-y ), the average content ratio of Al in the total amount of Ti and Al of the _{composite nitride layer or composite carbonitride layer x avg} and the composite nitride layer or composite carbonitride _{The average content ratio y avg} (where x _avg and y _avg are both atomic ratios) in the total amount of C and N in the layer C _{is 0.60 ≦ x avg} ≦ 0.95 and 0 ≦ y, respectively. _{Satisfying avg} ≤ 0.005,
(B) The hard coating layer contains at least crystal grains of the Ti and Al composite nitride layer or composite carbonitride having a NaCl-type face-centered cubic structure.
(C) Further, the crystal orientation of the crystal grains of the composite nitride or composite carbon nitride of Ti and Al having the NaCl-type face-centered cubic structure is analyzed from the longitudinal cross section using an electron beam backscattering diffractometer. Then, when crystal orientation mapping is performed by electron beam backward scattering diffraction, the crystal orientation relationship between each measurement point is analyzed, and the local orientation difference average (GAM value) of the measured crystal grains is obtained, the crystals of the crystal grains are obtained. A surface coating characterized in that crystal grains having an intra-grain local orientation difference average (GAM value) of less than 1 degree are present as an area ratio of 60% or more among the crystal grains having a NaCl-type face-centered cubic structure. Cutting tools.
(2) The crystal orientation of the crystal grains having a NaCl-type plane-centered cubic structure in the crystal grains constituting the composite nitride or composite carbon nitride layer is analyzed from the longitudinal cross-sectional direction using an electron beam rear scattering diffractometer. Then, when the average intragranular orientation difference (GOS value) of each crystal grain is obtained, the crystal grain having an average intragranular orientation difference (GOS value) of 1 degree or more is a composite nitride or a composite carbonic nitride. The surface cutting tool according to (1) above, wherein the crystal grains exhibiting less than 50% in the area ratio of the layer and 2 degrees or more are less than 20% in the area ratio of the composite nitride or composite carbon nitride layer. ..
(3) The hard coating layer is an individual having a NaCl-type cubic structure of the composite nitride or the composite carbonitride when observed from the longitudinal cross-sectional direction of the composite nitride or the composite carbonitride. The above (1) or (2), wherein the crystal grains have a columnar structure having an average particle width (W) of 0.1 to 2.0 μm and an average aspect ratio (A) of 2.0 to 10.0. ) The surface cutting tool described in any of.
(4) In the hard coating layer, the area ratio of the crystal grains of Ti and Al composite nitride or composite carbonitride having a NaCl-type face-centered cubic structure to the composite nitride or composite carbonitride layer is 95. The surface-coated cutting tool according to any one of (1) to (3) above, wherein the content is% or more.
(5) One or two or more Ti compounds among a carbide layer, a nitride layer, a carbonitride layer, a carbon oxide layer and a carbonitride oxide layer of Ti between the tool substrate and the hard coating layer. The surface cutting tool according to any one of (1) to (4) above, wherein a lower layer having an average layer thickness of 0.1 to 20.0 μm in total is present.
(6) The above (1), wherein one or more upper layers containing at least aluminum oxide are formed on the outer surface of the hard coating layer with an average film thickness of 1.0 to 25.0 μm in total. The surface cutting tool according to any one of (5). "

In the present invention, since the area ratio of the crystal grains whose local orientation difference average (GAM value) in the crystal grains is less than 1 degree in the hard coating layer is 60% or more, the toughness of the crystal grains is improved and the inside of the crystal grains is improved. Chipping resistance, heat crack resistance, and oxidation resistance are improved, and as a result, the surface cutting tool having this hard film exhibits excellent wear resistance and has a sufficient life as a tool. It exerts an excellent effect. Further, the crystal grains having an average orientation difference (GOS) of 1 degree or more in the crystal grains are less than 50% in the area ratio of the composite nitride or the composite carbonitride layer, or the crystal grains showing 2 degrees or more are the composite nitride or the composite. By setting the area ratio of the carbonitride layer to less than 20%, the toughness and oxidation resistance of the crystal grains are improved, and the above effects are further exhibited.

Local orientation difference in crystal grains having a NaCl-type face-centered cubic structure (cubic crystal) of a composite nitride layer of Ti and Al or a composite carbonitride, which is a hard coating layer of the surface coating cutting tool of the present invention. A schematic explanatory diagram of a method for measuring the average (GAM value) is shown. Average intragranular orientation difference of crystal grains having a NaCl-type face-centered cubic structure (cubic crystal) of a composite nitride layer of Ti and Al or a composite carbonitride, which is a hard coating layer of the surface coating cutting tool of the present invention. A schematic explanatory diagram of a method for measuring (GOS value) is shown. It is a film composition schematic diagram schematically showing the cross section of the composite nitride layer of Ti and Al or the composite carbonitride which constitutes the hard coating layer of the surface coating cutting tool of the present invention. Local orientation difference average (GAM value) area ratio of individual crystal grains having a cubic structure in the cross section of the composite nitride layer or composite carbonitride constituting the hard coating layer of the surface coating cutting tool of the present invention. It shows an example of a histogram about. In the cross section of the composite nitride layer or composite carbonitride constituting the hard coating layer of the surface coating cutting tool of the comparative example, the local orientation difference average (GAM value) area ratio in the grain of each crystal grain having a cubic structure. It shows an example of a histogram about.

The present invention will be described in detail.

Average layer thickness of composite nitride layer or composite carbonitride constituting the hard coating layer:
The hard coating layer of the surface coating cutting tool of the present invention is a composite nitride layer of Ti and Al represented by a _{chemically vapor-deposited composition formula: (Ti 1-x} Al _x ) ( _Cy N _1-y). It contains at least a composite carbonitride layer. This composite nitride layer or composite carbonitride layer has high hardness and excellent wear resistance, but the effect is remarkably exhibited particularly when the average layer thickness is 1.0 to 20.0 μm. .. The reason is that if the average layer thickness is less than 1.0 μm, the wear resistance over a long period of use cannot be sufficiently ensured because the average layer thickness is thin, while the average layer thickness exceeds 20.0 μm. This is because the crystal grains of the composite nitride layer of Ti and Al or the composite carbonitride layer are likely to be coarsened, and chipping is likely to occur.

Composition of composite nitride layer or composite carbonitride layer constituting the hard coating layer:
The composite nitride layer or composite carbonitride layer constituting the hard coating layer of the surface coating cutting tool of the present invention is a combination of the average content ratio x _avg and C and N of C in the total amount of Ti and Al of Al. The average content ratio y _{avg in the} amount (however, x _avg and y _avg are both atomic ratios) so as to satisfy _{0.60 ≤ x avg} ≤ 0.95 and 0 ≤ y _{avg ≤ 0.005, respectively.} Control.
The reason is that when the average content ratio x _avg of Al is less than 0.60, the composite nitride layer or composite carbonitride layer of Ti and Al is inferior in hardness, so that it is used for high-speed intermittent cutting of cast iron or the like. In some cases, the abrasion resistance is not sufficient, while when the average Al content x _avg exceeds 0.95, the Ti content is relatively reduced, resulting in embrittlement and chipping resistance. This is because it decreases.
The average content ratio y _avg of C is, 0 ≦ when y is _avg ≦ 0.005 range trace to improve the adhesion between the composite nitride layer or a composite carbonitride layer and the tool substrate or lower layer In addition, the improved lubricity alleviates the impact during cutting, and as a result, the fracture resistance and chipping resistance of the composite nitride layer or the composite carbonitride layer are improved. On the other hand, if the average content ratio y _avg of the C component deviates from the range of 0 ≦ y _avg ≦ 0.005, the toughness of the composite nitride layer or the composite carbonitride layer is lowered, so that the fracture resistance and chipping resistance are reversed. It is not preferable because it is impaired.

Local intra-grain orientation difference average (GAM value) and intra-grain average orientation difference (GOS value) of individual crystal grains having a NaCl-type cubic structure constituting the composite nitride or composite carbonitride:
In the present invention, an electron backscatter diffraction device is used to analyze at intervals of 0.01 μm from the longitudinal cross-sectional direction, and as shown in FIGS. 1 and 2, 5 degrees or more between adjacent measurement points (hereinafter referred to as pixels) P. If there is an orientation difference, it is defined as grain boundary B. Here, the vertical cross-sectional direction means a direction perpendicular to the vertical cross section. The vertical cross section means the cross section of the tool perpendicular to the surface of the tool substrate. Then, the region surrounded by the grain boundaries is defined as one crystal grain. However, a pixel that exists independently with all adjacent pixels and an orientation difference of 5 degrees or more is not regarded as a crystal grain, and a pixel in which two or more pixels are connected is treated as a crystal grain.
The average value of the local orientation difference in the crystal grain (GAM (Grain Average Missionation) value) referred to in the present invention is the average value of the orientation difference of all the adjacent pixels in the crystal grain having a cubic structure ( Figure 1). When expressing the GAM value by a mathematical formula, it can be expressed by the following formula (Equation 1). Here, m represents the number of boundaries between pixels in the crystal grain, and α _i represents the orientation difference at the boundary i of adjacent measurement points.
Further, the average orientation difference (GOS (Grain Origination Spread) value) in a crystal grain in the present invention is defined as a pixel in a crystal grain having a cubic structure and all other pixels in the same crystal grain. The orientation difference is calculated and averaged (Fig. 2). When expressing the GOS value by a mathematical formula, it can be expressed by the following formula (Equation 2). Here, n is the number of pixels in the same crystal grain, the numbers assigned to different pixels in the same crystal grain are i and j (here, 1 ≦ i and j ≦ n), and the crystal orientation in pixel i. The crystal orientation difference obtained from the crystal orientation at pixel j is expressed _{as α ij (i ≠ j).}

Here, the average local orientation difference (GAM value) in the crystal grains is analyzed at intervals of 0.01 μm from the longitudinal cross-sectional direction using an electron beam rear scattering diffractometer, and the width is 25 μm and the length is within the measurement range of the film thickness. Measurements from the longitudinal cross-sectional direction are performed in any of the five visual fields, and in each visual field, the NaCl-type face-centered cubic crystal grains constituting the composite nitride or the composite carbon nitride are adjacent to each other in the crystal grains. It is obtained by calculating the orientation difference between pixels and averaging it by the number of boundaries of adjacent pixels in the crystal grain, and arranging this in a histogram, and the crystal grains showing less than 1 degree are Al and Ti. Excellent wear resistance over long-term use when the composite nitride layer or composite carbon nitride layer is present in an area ratio of 60% or more with respect to the entire crystal grains having a NaCl-type face-centered cubic structure (Fig. 4). Has sex.
As described above, the crystal grains constituting the Al and Ti composite nitride layer or the composite carbonic nitride layer possessed by the surface coating cutting tool of the present invention are more crystalline than the crystal grains constituting the conventional TiAlN layer. Since the variation in crystal orientation within the grains is small, that is, the strain is small, it is presumed that this contributes to the improvement of oxidation resistance and toughness of the crystal grains.
The area ratio of the crystal grains having a local orientation difference average (GAM value) within the crystal grains of less than 1 degree to the area of the preferred composite nitride layer or composite carbonitride layer is 70% or more. Further, the crystal grains having a local orientation difference average (GAM value) within the crystal grains of less than 1 degree with respect to the area of the crystal grains having a NaCl-type face-centered cubic structure of the more preferable composite nitride layer or composite carbonitride layer. The area ratio is 80% or more.
Further, when the average intergranular orientation difference (GOS value) of each crystal grain is obtained, the crystal grains having the average intragranular orientation difference (GOS value) of 1 degree or more are composite nitrides or composite carbonitride layers. It is preferable that the area ratio of the above is less than 50%, or the crystal grains showing 2 degrees or more are less than 20% in the area ratio of the composite nitride or the composite carbonitride layer. This is because the crystal grains having an average orientation difference (GOS value) of 1 degree or more in the crystal grains are 50% or more or 2 degrees or more in the area ratio of the composite nitride or the composite carbonitride layer. A coating layer having an area ratio of 20% or more of the composite nitride or composite carbonitride layer may have many strains or defects in the crystal grains, and the effects of improving the toughness and oxidation resistance of the crystal grains may be reduced. Because of that.

Area ratio of Al and Ti composite nitride or composite carbonitride having a NaCl-type face-centered cubic structure:
The composite nitride layer or composite carbonitride layer of Ti and Al exhibits excellent wear resistance by containing crystal grains of the composite nitride layer or composite carbonitride having a NaCl-type face-centered cubic structure. When the area ratio of the crystal grains having the NaCl-type face-centered cubic structure to the composite nitride or composite carbonitride layer is 95% or more, particularly excellent wear resistance is exhibited.

Average crystal width W and average aspect ratio A of individual crystal grains having a NaCl-type cubic structure of a composite nitride layer or composite carbonitride when observed from the longitudinal direction.
The average particle width W of individual crystal grains having a NaCl-type cubic structure in the composite nitride layer of Ti and Al or the composite carbonitride layer is 0.1 to 2.0 μm, and the average aspect ratio A is 2 to 10. By forming the columnar structure so as to have a columnar structure, the above-mentioned effect of improving toughness and abrasion resistance can be further exhibited.
That is, the average particle width W was set to 0.1 to 2.0 μm when the average particle width W was less than 0.1 μm, (Ti _1-x Al _x ) ( _Cy N _1-y ) crystals in the atoms exposed on the surface of the coating layer. As the proportion of atoms belonging to the grain boundaries becomes relatively large, the reactivity with the work material increases, and as a result, the abrasion resistance cannot be sufficiently exhibited and exceeds 2.0 μm. _{The proportion of atoms belonging to the (Ti 1-x} Al _x ) ( _Cy N _1-y ) grain boundaries in the entire hard coating layer is relatively small, so that the toughness is reduced and the chipping resistance is sufficient. This is because it cannot be exerted on.
Further, when the average aspect ratio A is less than 2, the columnar structure is not sufficient, which causes the equiaxed crystals having a small aspect ratio to fall off, and as a result, sufficient wear resistance cannot be exhibited. On the other hand, if the average aspect ratio A exceeds 10, the strength of the crystal grains themselves cannot be maintained, and on the contrary, the chipping resistance is lowered, which is not preferable.
In the present invention, the average aspect ratio A is defined as the surface of the tool substrate when the vertical cross section of the hard coating layer is observed in a range of 100 μm in width and 100 μm in height including the entire hard coating layer using a scanning electron microscope. Observe from the side of the coating cross section perpendicular to the surface of the coating, measure the particle width w in the direction parallel to the surface of the substrate and the particle length l in the direction perpendicular to the surface of the tool substrate, and measure the aspect ratio a (= l / w) of each crystal grain. Was calculated, the average value of the aspect ratio a obtained for each crystal grain was calculated as the average aspect ratio A, and the average value of the particle width w obtained for each crystal grain was calculated as the average particle width W. ..

Lower and upper layers:
The Ti and Al composite nitride layer or composite carbonitride layer of the surface coating cutting tool of the present invention sufficiently exerts the above-mentioned effect by itself, but Ti carbide layer, nitride layer, carbonitride layer, carbonic acid. When a lower layer composed of one or more Ti compound layers of a compound layer and a carbonitride oxide layer and having an average layer thickness of 0.1 to 20.0 μm in total is provided, and / or When the upper layer including the aluminum oxide layer having an average layer thickness of 1 to 25 μm in total is provided, more excellent characteristics can be created in combination with the effects of these layers. When a lower layer composed of one or more Ti compound layers of a carbide layer, a nitride layer, a carbonitride layer, a coal oxide layer and a carbon dioxide oxide layer of Ti is provided, the total average layer of the lower layers is provided. If the thickness 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 are likely to be coarsened and chipping is likely to occur. Further, if the total average layer thickness of the upper layer including the aluminum oxide layer is less than 1 μm, the effect of the upper layer is not sufficiently exhibited, while if it exceeds 25 μm, the crystal grains are likely to be coarsened and chipping is likely to occur. ..

A cross section of a composite nitride layer or a composite carbonitride layer of Ti and Al constituting the hard coating layer of the present invention is schematically shown in FIG.

Next, the covering tool of the present invention will be specifically described with reference to Examples.
As an example, a coated tool using a WC-based cemented carbide as a tool base will be described, but the same applies to the case where a TiCN-based cermet and a cBN-based ultrahigh-pressure sintered body are used as the tool base.

As raw material powders, WC powder, TiC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder and Co powder having an average particle size of 1 to 3 μm are prepared, and these raw material powders are blended as shown in Table 1. It was blended into the composition, further added with wax, mixed in a ball mill in acetone for 24 hours, dried under reduced pressure, press-molded into a green compact of a predetermined shape at a pressure of 98 MPa, and this green compact was pressed in a vacuum of 5 Pa at 1370. Vacuum sintered at a predetermined temperature within the range of ~ 1470 ° C. under the condition of holding for 1 hour, and after sintering, manufacture tool bases A to C made of WC-based superhard alloy having an insert shape of ISO standard SEEN1203AFSN. did.

Next, a CVD device is used on the surfaces of these tool bases A to C.
(A) From the formation conditions A to G shown in Tables 3 and 4, that is, the gas group A composed of _{NH 3} , N ₂ and H _{2 , and AlCl 3} , TiCl ₄ , Al (CH ₃ ) ₃ , and H _2. Gas group B is supplied.
(B) _{Upon supply, the amount of NH 3} supplied in the gas group A is relatively small, and N ₂ is supplied to the gas group A at least four times as much as NH _{3 , and then N 2} / (AlCl ₃ + Al (CH ₃ )). _{It is preferable that 3} ) does not become too large in order to obtain the hard coating layer according to the present invention.
More specifically, the reaction gas composition is expressed in% by volume (ratio of gas group A and gas group B to the total).
Gas group A NH ₃ : 1.0 to 1.9%, N ₂ : 6.0 to 10.0%, H ₂ : 40.0 to 50.0%
Gas group B AlCl ₃ : 0.60 to 0.90%, TiCl ₄ : 0.10 to 0.40%, Al (CH ₃ ) ₃ : 0.00 to 0.10%, H ₂ : Remaining (d) Reaction atmosphere pressure: 4.5-5.0 kPa
Reaction atmosphere temperature: 700-900 ° C
Supply cycle: 1 to 5 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, heat for a predetermined time By performing the CVD method, crystal grains showing an average local orientation difference of less than 1 degree in the crystal grains are present at the ratio shown in Table 5, and have the thickness shown in the same table (Ti _1-x Al _x ) ( _Cy N). The coating tools 1 to 15 of the present invention in which a hard coating layer including a _{1-y) layer was formed were manufactured.}
For some of the covering tools of the present invention, the lower layer and / or the upper layer shown in Table 5 were formed under the formation conditions shown in Table 2.

Further, for the purpose of comparison, at least a composite nitride layer of Ti and Al or composite carbonitride is formed on the surfaces of the tool substrates A to C under the conditions shown in Tables 3 and 4, as in the case of the coated tools 1 to 15 of the present invention. A hard coating layer including a material layer was formed by vapor deposition. Similar to the covering tool of the present invention, for some of the comparative covering tools, the lower layer and / or the upper layer shown in Table 6 were formed under the formation conditions shown in Table 2.

The cross section of each constituent layer of the covering tools 1 to 15 and the comparative covering tools 1 to 15 in the direction perpendicular to the tool substrate was measured using a scanning electron microscope (magnification of 5000 times), and 5 points in the observation field of view. The average layer thickness was obtained by measuring and averaging the layer thickness.

_{Regarding the average Al content x avg} of the composite nitride layer or the composite carbonic nitride layer, an electron beam was used in a sample whose surface was polished using an electron probe microanalyzer (Electron-Probe-Micro-Analyzer: EPMA). Was irradiated from the sample surface side, and the average Al content ratio x _avg was obtained from the 10-point average of the obtained characteristic X-ray analysis results. The average content ratio of C, y _avg , was determined by secondary ion mass spectrometry (Secondary-Ion-Mass-Spectroscopy: SIMS). An ion beam was irradiated in a range of 70 μm × 70 μm from the sample surface side, and the concentration of the component released by the sputtering action was measured in the depth direction. The average content ratio y _avg of C indicates the average value in the depth direction for the composite nitride layer or composite carbonitride layer of Ti and Al.

Furthermore, the crystal orientation of each crystal grain having a NaCl-type cubic structure constituting the Ti and Al composite nitride layer or the composite carbon nitride layer is analyzed from the longitudinal cross-sectional direction using an electron beam rear scattering diffractometer. If there is an orientation difference of 5 degrees or more between adjacent pixels, that is the grain boundary, the area surrounded by the grain boundary is one crystal grain, and one pixel in the crystal grain and another in the same crystal grain. The intergranular orientation difference is calculated between all the pixels of, and the average local orientation difference (GAM value) in the crystal grain is 0 degrees or more and less than 1 degree, 1 degree or more and less than 2 degrees, 2 degrees or more and less than 3 degrees, 3 degrees or more. The range of less than 4 degrees, ..., And 0 to 10 degrees was separated for each degree and mapped. From the mapping diagram, the crystal grains having a local orientation difference average (GAM value) of less than 1 degree in the crystal grains are a NaCl-type face-centered cubic structure of a composite nitride layer of Ti and Al or a composite carbonic nitride layer. A crystal grain having an area ratio to the entire grain and an average orientation difference (GOS value) within the crystal grain of 1 degree or more or 2 degrees or more is a NaCl-type face-centered cubic structure of a composite nitride or composite carbon nitride layer. The area ratio to the total crystal grains was calculated. The results are shown in Tables 5 and 6. FIG. 4 shows an example of a histogram of the average intragranular orientation difference (GAM value) measured for the coating tool 7 of the present invention, and FIG. 5 shows the average intragranular orientation difference measured for the comparative coating tool 4. An example of the average histogram is shown.

Next, with the various covering tools clamped to the tip of a tool steel cutter having a cutter diameter of 50 mm with a fixing jig, the covering tools 1 to 8 of the present invention and the comparative covering tools 1 to 8 are described below. Under the cutting condition A shown, a wet milling cutting test, which is a kind of high-speed intermittent cutting of cast iron, was carried out, and the flank wear width of the cutting edge was measured. The results are shown in Table 7.
≪Cutting condition A≫
Tool base: WC-based cemented carbide Cutting test: Wet milling,
Work material: Ductile cast iron FCD 700 Block material with width 100 mm and length 400 mm Rotation speed: 994 min ^-1 ,
Cutting speed: 350 m / min,
Notch: 1.0 mm,
Single blade feed amount: 0.4 mm / blade,
Cutting time: 6 minutes (normal cutting speed is 200 m / min)

Further, with the various covering tools screwed to the tip of the tool steel cutting tool with a fixing jig, the covering tools 9 to 15 of the present invention and the covering tools 9 to 15 of the comparative example are cut as shown below. Under condition B, a dry high-speed intermittent cutting test of cast iron was carried out, and the flank wear width of the cutting edge was measured. The results are shown in Table 8.
≪Cutting condition B≫
Tool base: WC-based cemented carbide Work material: JIS / FCD800 8 round bars with vertical grooves at equal intervals in the length direction Cutting speed: 350 m / min,
Notch: 1.5 mm,
Single blade feed amount: 0.2 mm / blade,
Cutting time: 4 minutes (normal cutting speed is 200 m / min)

From the results shown in Tables 7 and 8, the coating tool of the present invention is used in the NaCl-type cubic grain grains constituting the Al and Ti composite nitride layer or the composite carbon nitride layer constituting the hard coating layer. Since the ratio of crystal grains showing an average local orientation difference (GAM value) of less than 1 degree in the crystal grains is 60% or more in terms of area ratio, excellent oxidation resistance is exhibited and high wear resistance is maintained. Excellent toughness and excellent chipping resistance and fracture resistance even when used for high-speed intermittent cutting in which a high load is applied to the cutting edge intermittently and impactfully. As a result, excellent wear resistance over a long period of use. Is demonstrating.

On the other hand, in the NaCl-type cubic crystal grains constituting the Al and Ti composite nitride layer or the composite carbon nitride layer constituting the hard coating layer, the local orientation difference average (GAM value) in the crystal grains is For comparative covering tools 1 to 15 in which the ratio of crystal grains indicating less than 1 degree is less than 60% in terms of area ratio, high-speed intermittent cutting is accompanied by high heat generation and intermittent and impactful high load acts on the cutting edge. When used in, the toughness and oxidation resistance of the film are inferior, and the life is reached in a short time due to the occurrence of thermal cracks, chipping, defects, and the like.

As described above, the coating tool of the present invention can be used not only for high-speed intermittent cutting of cast iron, but also as a coating tool for various work materials, and has excellent chipping resistance and abrasion resistance over a long period of use. Since it exhibits its properties, it can sufficiently and satisfactorily cope with high performance of cutting equipment, labor saving and energy saving of cutting processing, and cost reduction.

P measurement point (pixel)
B grain boundary

Claims (6)

In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool substrate composed of either a tungsten carbide-based cemented carbide, a titanium nitride-based cermet, or a cubic boron nitride-based ultrahigh-pressure sintered body.
(A) The hard coating layer contains at least a composite nitride layer or a composite carbonitride layer of Ti and Al having an average layer thickness of 1.0 to 20.0 μm, and has a composition formula: (Ti _1-x Al _x ). When _{represented by (Cy} N _1-y ), the average content ratio of Al in the total amount of Ti and Al of the _{composite nitride layer or composite carbonitride layer x avg} and the composite nitride layer or composite carbonitride _{The average content ratio y avg} (where x _avg and y _avg are both atomic ratios) in the total amount of C and N in the layer C _{is 0.60 ≦ x avg} ≦ 0.95 and 0 ≦ y, respectively. _{Satisfying avg} ≤ 0.005,
(B) The hard coating layer contains at least crystal grains of the Ti and Al composite nitride layer or composite carbonitride having a NaCl-type face-centered cubic structure.
(C) Further, the crystal orientation of the crystal grains of the composite nitride or composite carbon nitride of Ti and Al having the NaCl-type face-centered cubic structure is analyzed from the longitudinal cross section using an electron beam backscattering diffractometer. Then, when crystal orientation mapping is performed by electron beam backward scattering diffraction, the crystal orientation relationship between each measurement point is analyzed, and the local orientation difference average (GAM value) of the measured crystal grains is obtained, the crystals of the crystal grains are obtained. A surface coating characterized in that crystal grains having an intra-grain local orientation difference average (GAM value) of less than 1 degree are present as an area ratio of 60% or more among the crystal grains having a NaCl-type face-centered cubic structure. Cutting tools. The crystal orientation of the crystal grains having a NaCl-type plane-centered cubic structure in the crystal grains constituting the composite nitride or composite carbon nitride layer is analyzed from the longitudinal cross-sectional direction using an electron beam rear scattering diffractometer, and the crystals are crystallized. When the average intergranular orientation difference (GOS value) of each grain is determined, the crystal grain having an average intragranular orientation difference (GOS value) of 1 degree or more is the area of the composite nitride or composite carbonic nitride layer. The surface cutting tool according to claim 1, wherein the crystal grains exhibiting a ratio of less than 50% and 2 degrees or more are less than 20% in terms of the area ratio of the composite nitride or composite carbon nitride layer. The hard coating layer is an individual crystal grain having a NaCl-type cubic structure of the composite nitride or the composite carbonitride when observed from the longitudinal cross-sectional direction of the composite nitride or the composite carbonitride. The invention according to any one of claims 1 or 2, wherein the columnar structure has an average particle width (W) of 0.1 to 2.0 μm and an average aspect ratio (A) of 2.0 to 10.0. Surface cutting tool. In the hard coating layer, the area ratio of the crystal grains of Ti and Al composite nitride or composite carbonitride having a NaCl-type face-centered cubic structure to the composite nitride or composite carbonitride layer is 95% or more. The surface-coated cutting tool according to any one of claims 1 to 3, wherein the surface coating cutting tool is provided. Between the tool substrate and the hard coating layer, it is composed of one or more Ti compound layers of a carbide layer of Ti, a nitride layer, a carbonitride layer, a carbon oxide layer and a carbonitride oxide layer. The surface cutting tool according to any one of claims 1 to 4, wherein a lower layer having an average layer thickness of 0.1 to 20.0 μm in total is present. Any of claims 1 to 5, wherein one or more upper layers containing at least aluminum oxide are formed on the outer surface of the hard coating layer with an average film thickness of 1.0 to 25.0 μm in total. The surface cutting tool described in item 1.

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