WO2018066469A1 - Surface-coated cutting tool with hard coating layer exhibiting excellent chipping resistance - Google Patents

Surface-coated cutting tool with hard coating layer exhibiting excellent chipping resistance Download PDF

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Publication number
WO2018066469A1
WO2018066469A1 PCT/JP2017/035466 JP2017035466W WO2018066469A1 WO 2018066469 A1 WO2018066469 A1 WO 2018066469A1 JP 2017035466 W JP2017035466 W JP 2017035466W WO 2018066469 A1 WO2018066469 A1 WO 2018066469A1
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layer
grain boundary
constituent
lattice point
boundary length
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PCT/JP2017/035466
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French (fr)
Japanese (ja)
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正樹 奥出
西田　真
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三菱マテリアル株式会社
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Priority claimed from JP2017174844A external-priority patent/JP6928220B2/en
Application filed by 三菱マテリアル株式会社 filed Critical 三菱マテリアル株式会社
Publication of WO2018066469A1 publication Critical patent/WO2018066469A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B27/00—Tools for turning or boring machines; Tools of a similar kind in general; Accessories therefor
    • B23B27/14—Cutting tools of which the bits or tips or cutting inserts are of special material
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • C23C16/36—Carbonitrides

Definitions

  • the present invention demonstrates excellent chipping resistance even when cutting steel or stainless steel under high-speed intermittent high-cutting conditions and high-speed intermittent high-feed conditions where a high load acts on the cutting blade.
  • the present invention also relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent cutting performance over a long period of time.
  • a substrate (hereinafter collectively referred to as a tool substrate) composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet.
  • the lower layer is a Ti carbide (hereinafter referred to as TiC) layer, a nitride (hereinafter also referred to as TiN) layer, a carbonitride (hereinafter referred to as TiCN) layer, a carbon oxide (hereinafter referred to as TiCO).
  • TiCNO carbonitride oxide
  • Al 2 O 3 layer aluminum oxide layer having an ⁇ -type crystal structure in a state where the upper layer is chemically vapor-deposited
  • the conventional coated tools as described above exhibit excellent cutting performance in continuous cutting of, for example, various types of steel and cast iron.
  • chipping of the coating layer is performed.
  • tool life tends to occur and the tool life is shortened. Therefore, in order to improve the chipping resistance of the coating layer, a coating tool in which various improvements are added to the hard coating layer has been proposed.
  • Patent Document 1 discloses that On the surface of the tool base, (A) The lower layer is composed of two or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer, all formed by chemical vapor deposition, and 3 A Ti compound layer having a total average layer thickness of ⁇ 20 ⁇ m, (B) an aluminum oxide layer having an average layer thickness of 1 to 15 ⁇ m, wherein the upper layer is formed by chemical vapor deposition;
  • One layer of the Ti compound layer of the above (a) Reaction gas composition: volume%, TiCl 4 : 0.1 to 0.8%, CH 3 CN: 0.05 to 0.3%, Ar: 10 to 30%, H 2 : remaining, Reaction atmosphere temperature: 930 to 1000 ° C., Reaction atmosphere pressure: 6-20 kPa, Under the conditions, chemical vapor deposition is formed to an average layer thickness of 2.5 to 15 ⁇ m, Using
  • the inclination angle formed by the normal lines of the (001) plane and the (011) plane, which are the crystal planes of the crystal grains, with respect to the normal line of the surface-polished surface is measured.
  • Each of the constituent atoms has an NaCl-type cubic crystal structure in which constituent atoms composed of carbon and nitrogen are present, and each of the constituent atoms is formed at the interface between adjacent crystal grains based on the measured tilt angle.
  • N is Each of the constituent atomic shared lattice point forms (unit forms) represented by ⁇ N + 1 defined for each of the even number of 2 or more on the crystal structure of the aCl type cubic crystal, with N: 28 being the upper limit in terms of distribution frequency)
  • the distribution ratio of each constituent atom shared lattice point form (unit form) of ⁇ 3 to ⁇ 29 is accounted for in the total distribution ratio of the constituent atom shared lattice point forms (unit form) of ⁇ 3 to ⁇ 29.
  • a coated tool composed of a titanium carbonitride layer showing a constituent atomic share lattice point distribution graph has been proposed. According to this coated tool, a high resistance to chipping with a hard coating layer can be achieved by high-speed intermittent cutting of steel or cast iron. It has been to exert a ring of.
  • the lower layer is composed of two or more of titanium carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer, all formed by chemical vapor deposition; and One of them is a titanium compound layer comprising a titanium carbonitride layer and having a total average layer thickness of 3 to 20 ⁇ m, (B) an aluminum oxide layer having an average layer thickness of 1 to 15 ⁇ m, wherein the upper layer is formed by chemical vapor deposition;
  • the coated tool formed by forming the hard coating layer composed of (a) and (b) above For the titanium carbonitride layer in the titanium compound layer of (a) above, using a field emission scanning electron microscope, each crystal grain present within the measurement range of the longitudinal section is irradiated with an electron beam, and electron backscattering is performed.
  • the crystal grains have a NaCl-type face-centered cubic crystal structure in which constituent atoms composed of Ti, carbon, and nitrogen are present at lattice points, respectively.
  • the distribution ratios of the constituent atom shared lattice point forms (unit forms) represented by ⁇ N + 1 are calculated, and the distribution ratios of the constituent atom shared lattice point forms (unit forms) of ⁇ 3 to ⁇ 29 are calculated as ⁇ 3 to ⁇ 29.
  • the distribution ratio of ⁇ 3 is the constituent atomic shared lattice point form (unit form) at the cutting edge ridge line portion.
  • the distribution ratio of ⁇ 3 accounts for 50% or more of the total distribution ratio of the constituent atom shared lattice point form (unit form) Constituent Carbonitride layer of titanium that shows the sharing lattice point distribution graph, A coating tool that exhibits excellent chipping resistance in a strong interrupted machining is proposed.
  • the distribution ratio of ⁇ 3 in the lower layer of the hard coating layer of the cutting edge ridge line and the cutting edge ridge line Wear resistance in hard interrupted processing where the interrupting interval is long and a strong impact is applied to the cutting edge tip by setting the distribution ratio of ⁇ 3 of the lower layer of the hard coating layer in a region other than the part to a specific range, respectively. It is said that excellent chipping resistance is exhibited without incurring a decrease in the thickness.
  • the present inventors are subjected to intermittent and shocking high loads on the cutting edge, and high-speed intermittent heavy cutting conditions in which plastic deformation of the hard coating layer is likely to occur (for example, Even when used under high-speed, high-cut high-intermittent cutting conditions and high-speed, high-feed intermittent cutting conditions), the hard coating layer structure that does not cause peeling or chipping of the hard coating layer has been studied.
  • the length ratio of the corresponding grain boundary length of ⁇ 31 or more to the total corresponding grain boundary length of the TiCN layer is set to 80% or more, thereby forming the TiCN constituting the lower layer Grain boundaries with high toughness can be distributed in the layer, which makes it possible to produce steel, stainless steel under high-speed, high-cut and high-feed intermittent conditions where intermittent and impactful high loads are applied to the cutting edge.
  • the length ratio of the corresponding grain boundary length of ⁇ 31 or more to the total corresponding grain boundary length of the TiCN layer is set to 80% or more, thereby forming the TiCN constituting the lower layer Grain boundaries with high toughness can be distributed in the layer, which makes it possible to produce steel, stainless steel under high-speed, high-cut and high-feed intermittent conditions where intermittent and impactful high loads are applied to the cutting edge.
  • peeling of the hard coating layer generation of chipping was found to be suppressed.
  • the present invention has been made based on the above findings, “(1) In a surface-coated cutting tool in which a hard coating layer composed of a lower layer and an upper layer is provided on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet, (A) The lower layer is a Ti compound layer having a total average layer thickness of 3 to 20 ⁇ m and comprising one or more of TiC, TiN, TiCN, TiCO, and TiCNO, At least one layer is composed of a TiCN layer, (B) the upper layer comprises an Al 2 O 3 layer having an average layer thickness of 1 to 15 ⁇ m and having an ⁇ -type crystal structure; (C) At least one TiCN layer of the lower layer is irradiated with an electron beam on each crystal grain existing within the measurement range of the longitudinal section of the at least one TiCN layer using a field emission scanning electron microscope.
  • the crystal grains have a NaCl type face-centered cubic crystal structure in which constituent atoms composed of Ti, carbon, and nitrogen are present at lattice points, respectively.
  • the distribution of lattice points in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains is calculated.
  • the grain boundary length of the constituent atom shared lattice point form (unit form) which is ⁇ 31 or more is Occupy 80% of the grain boundary length of the constituent atomic shared lattice point form (unit form) which is ⁇ 3 or more
  • At least one TiCN layer of the lower layer is irradiated with an electron beam on each crystal grain existing within the measurement range of the longitudinal section of the at least one TiCN layer using a field emission scanning electron microscope. Then, using an electron backscatter diffraction image apparatus, the normal areas of the (001) plane and (011) plane, which are crystal planes of the crystal grains, with respect to the normal line of the substrate surface with respect to the normal line of the predetermined region at an interval of 0.1 ⁇ m / step In this case, the crystal grains have a NaCl type face-centered cubic crystal structure in which constituent atoms composed of Ti, carbon, and nitrogen are present at lattice points, respectively.
  • the distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains is calculated.
  • the distribution ratio of each constituent atom shared lattice point form (unit form) represented by ⁇ N + 1 determined for each number N of lattice points that do not share constituent atoms existing between the shared atomic lattice points is calculated as ⁇ 3
  • the grain boundary length of the constituent atomic shared lattice point form (unit form) of is not more than 20% of the grain boundary length of the constituent atomic shared lattice point form (unit form) of ⁇ 3 to ⁇ 29, and the constituent atomic shared lattice of ⁇ 5
  • the Ti compound layer constituting the lower layer is composed of one or more of TiC layer, TiN layer, TiCN layer, TiCO layer and TiCNO layer (however, at least one of them is a TiCN layer).
  • the hard coating layer exists as a lower layer of an Al 2 O 3 layer having an ⁇ -type crystal structure (hereinafter referred to as “ ⁇ -Al 2 O 3 layer”), and has a high temperature strength possessed by itself. High temperature strength is given to.
  • the Ti compound layer is in close contact with both the tool base surface and the upper layer composed of the ⁇ -Al 2 O 3 layer, and has an action of maintaining the adhesion of the hard coating layer to the tool base.
  • the total average layer thickness of the Ti compound layer is determined to be 3 to 20 ⁇ m.
  • At least one TiCN layer of the lower layer includes at least one TiCN layer.
  • the constituent atom sharing lattice point distribution graph is obtained for the at least one TiCN layer, the constituent atom sharing in which the grain boundary length of the constituent atom sharing lattice point form (unit form) is ⁇ 31 or more is ⁇ 3 or more. It is important to occupy 80% or more of the grain boundary length in the lattice point form (unit form).
  • the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 31 or more occupies 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 or more, in the TiCN layer Since many grain boundaries with excellent toughness are distributed, the impact relaxation properties of the TiCN layer are improved and the hard coating layer can be deformed following the deformation of the tool base. In high-speed intermittent heavy cutting of steel or the like, occurrence of chipping is suppressed.
  • the TiCN layer occupying 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) in which the constituent atom shared lattice point form (unit form) is ⁇ 3 or more.
  • An example of the constituent atom shared lattice point distribution graph of is shown.
  • the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 is 20% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 to ⁇ 29, and the constituent atom of ⁇ 5
  • the toughness of the TiCN layer is further improved.
  • the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 is 20% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 to ⁇ 29
  • the constituent atom of ⁇ 5 Example of constituent atomic shared lattice point distribution graph of TiCN layer in which the grain boundary length of the shared lattice point form (unit form) is 30% or less of the grain boundary length of the constituent atomic shared lattice point form (unit form) of ⁇ 3 to ⁇ 29 Indicates.
  • the constituent atomic shared lattice distribution graph is obtained by using a field emission scanning electron microscope, for example, a longitudinal section parallel to the layer thickness direction of the lower layer of the hard coating layer.
  • the crystal grains existing within the measurement range of the surface are irradiated with an electron beam, and the electron backscatter diffraction image apparatus is used to divide the predetermined region at a distance of 0.1 ⁇ m / step with respect to the normal line of the surface polished surface.
  • the inclination angle formed by the normal lines of the (001) plane and the (011) plane, which are crystal planes of the crystal grains, is measured (in this case, each of the crystal grains has constituent atoms composed of Ti, carbon, and nitrogen at lattice points.
  • One between the grains The distribution of lattice points that share constituent atoms (constituent atom shared lattice points) is calculated, and the number N of lattice points that do not share constituent atoms existing between the constituent atom shared lattice points (in this case, N is a NaCl-type surface) It is an even number of 2 or more in terms of the crystal structure of the centered cubic crystal.)
  • Each grain boundary length of the constituent atom shared lattice point form (unit form) represented by ⁇ N + 1 defined for each is calculated, and each structure of ⁇ 3 or more
  • a constituent atomic shared lattice point distribution graph is created that shows the grain boundary length of the atomic shared lattice point form (unit form) as a percentage of the total grain boundary length of the constituent atomic shared lattice form (unit form) of ⁇ 3 or more.
  • the sum of the grain boundary lengths of ⁇ 31 or more was grouped as ⁇ 31 or more instead of calculating the grain boundary length in each N of ⁇ 31 or more. That is, the grain boundary lengths of ⁇ 3, ⁇ 5, ⁇ 7, ⁇ 9, ⁇ 11, ⁇ 13, ⁇ 15, ⁇ 17, ⁇ 19, ⁇ 21, ⁇ 23, ⁇ 25, ⁇ 27, and ⁇ 29 are calculated, and all grain boundaries greater than or equal to ⁇ 3 obtained by measurement A value obtained by subtracting the total grain boundary length from ⁇ 3 to ⁇ 29 from the length was obtained as the total grain boundary length of ⁇ 31 or more.
  • the grain boundary length of the constituent atom shared lattice point form (unit form) that is ⁇ 31 or more has a TiCN layer that accounts for 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) that is ⁇ 3 or more.
  • the lower layer can be formed as follows, for example. That is, first, a Ti compound layer composed of one or more of TiC layer, TiN layer, TiCN layer, TiCO layer, and TiCNO layer is hard-coated on the tool base surface using a normal chemical vapor deposition apparatus. Vapor deposition is performed as a lower layer of the layer (note that it is of course possible to deposit only the TiCN layer).
  • Reaction gas composition (volume%): TiCl 4 1-3%, CH 3 CN 0.3-1.0%, N 2 25-60%, HCl 0.05% -0.2%, Ar 3-15% , Balance H 2 , Reaction atmosphere temperature: 750 to 900 ° C. Reaction atmosphere pressure: 5 to 10 kPa, By performing chemical vapor deposition under the conditions, a TiCN layer having the predetermined constituent atom shared lattice point form (unit form) can be formed.
  • the grain boundary length of the constituent atom shared lattice point form (unit form) which is ⁇ 31 or more formed by vapor deposition is 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) which is ⁇ 3 or more.
  • the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 is 20% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 to ⁇ 29
  • the TiCN layer in which the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 5 is 30% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 to ⁇ 29 It can be formed by performing under limited conditions. For example, the conditions are as follows.
  • Reaction gas composition (volume%): TiCl 4 2-3%, CH 3 CN 0.5-0.8%, N 2 25-45%, HCl 0.08% -0.15%, Ar 5-10% , Balance H 2 , Reaction atmosphere temperature: 820 to 900 ° C. Reaction atmosphere pressure: 5 to 7 kPa,
  • the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 is 20% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 to ⁇ 29
  • a TiCN layer in which the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 5 is 30% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 to ⁇ 29 is formed. Can do.
  • the lower TiCN layer having a specific constituent atomic shared lattice point form (unit form) formed by the chemical vapor deposition method has a columnar vertically elongated structure.
  • the area ratio occupied by columnar vertically grown TiCN crystal grains having an aspect ratio of 3 or more determined from the maximum grain width W of the TiCN crystal grains of the TiCN layer and the maximum grain length L in the layer thickness direction is the longitudinal section of the TiCN layer. It is 80% by area or more of the surface area, and an excellent effect of improving wear resistance, which is a feature of the columnar vertically long structure, can be expected.
  • the maximum particle width W and the maximum particle length L are the crystal in the direction perpendicular to the layer thickness direction when one crystal grain in the longitudinal section of the TiCN layer is measured for the columnar vertically grown TiCN crystal grains.
  • the largest value of the grain width (short side) is called the maximum grain width W
  • the maximum grain height (long side) in the layer thickness direction is called the maximum grain length L.
  • the distribution of the maximum particle width W is calculated in the longitudinal section of the TiCN layer, and the value indicating the maximum peak in the distribution is preferably 0.3 to 1.0 ⁇ m, and the maximum peak value of the W distribution is 0.3 TiCN crystal grains less than that cannot be expected to have an excellent effect of improving wear resistance, which is a feature of columnar vertically long structure.
  • the maximum peak value of W distribution is larger than 1.0, TiCN crystal grains become coarse and hard. It tends to cause chipping of the coating layer.
  • Upper layer An upper ⁇ -Al 2 O 3 layer is formed on the surface of the lower layer formed in the above by a conventionally known chemical vapor deposition method. If the average thickness of the upper layer is less than 1 ⁇ m, a long-term Excellent wear resistance cannot be exhibited over use. On the other hand, if the thickness exceeds 15 ⁇ m, chipping tends to occur. Therefore, the thickness of the upper layer is determined to be 1 to 15 ⁇ m.
  • the hard coating layer has a lower layer formed on the surface of the tool base and an upper layer formed on the lower layer, and the lower layer is TiC, TiN, TiCN, TiCO, TiCNO. And at least one of them is a TiCN layer, and the TiCN layer is a corresponding grain composed of each constituent atom shared lattice point in the total corresponding grain boundary length.
  • the grain boundary length of the constituent atom shared lattice point form (unit form) that is ⁇ 31 or more is of the constituent atom shared lattice point form (unit form) that is ⁇ 3 or more.
  • the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 is equal to the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 to ⁇ 29. 20% or less, and ⁇ 5 constituent atom sharing
  • the grain boundary length in the sub-point form (unit form) is 30% or less of the grain boundary length in the constituent atomic shared lattice point form (unit form) of ⁇ 3 to ⁇ 29, so that the TiCN layer has a high toughness grain boundary. Many are distributed.
  • the coated tool of the present invention even when cutting of steel, stainless steel, etc., is performed under high-speed high-cutting intermittent conditions or high-speed high-feed intermittent conditions where intermittent and impactful high loads act on the cutting blade, Occurrence of chipping and peeling of the hard coating layer is suppressed, and excellent cutting performance is exhibited over a long period of use.
  • Constituent atomic shared lattice showing the ratio of the grain boundary length of each constituent atomic shared lattice point form (unit form) to the total corresponding grain boundary length of the TiCN layer of the lower layer of the coated tool of the present invention Indicates.
  • a point distribution graph is shown.
  • constituent atom shared lattice point distribution graph showing the ratio of the grain boundary length of each constituent atom shared lattice point form (unit form) to the total corresponding grain boundary length of the TiCN layer of the lower layer of the coated tool of the present invention
  • Constituent atomic shared lattice points showing the ratio of the grain boundary length of each constituent atomic shared lattice point form (unit form) to the corresponding grain boundary length of ⁇ 3 to ⁇ 29 of the TiCN layer of the lower layer of the coated tool of the present invention shown in FIG.
  • a distribution graph is shown.
  • coated tool of the present invention will be specifically described based on examples.
  • WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr 3 C 2 powder, TiN powder, and Co powder each having an average particle diameter of 1 to 3 ⁇ m are prepared. Then, blended into the composition shown in Table 1, added with wax, ball mill mixed in acetone for 24 hours, dried under reduced pressure, and then press-molded into a green compact of a predetermined shape at a pressure of 98 MPa.
  • WC-based cemented carbide tool having an ISO standard CNMG120408 insert shape after being sintered in a vacuum of 5 Pa at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour. Substrates A to D were produced respectively.
  • ZrC powder ZrC powder
  • TaC powder Mo 2 C powder
  • WC powder Co powder all having an average particle diameter of 0.5 to 2 ⁇ m
  • Ni powder these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and then pressed into a compact at a pressure of 98 MPa.
  • the body was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, a tool base E made of TiCN-based cermet having an insert shape of ISO standard CNMG120212 was produced.
  • each of the tool bases A to D and the tool base E was charged into a normal chemical vapor deposition apparatus, and a hard coating layer was formed by the following steps.
  • an ⁇ -Al 2 O 3 layer as an upper layer having the target layer thickness shown in Table 8 was formed by vapor deposition under the conditions shown in Table 3.
  • the inventive coated tools 1 to 13 having the hard coating layer shown in Tables 6 and 8 were produced, respectively.
  • comparative coating tools 1 to 13 having the hard coating layers shown in Tables 7 and 9 are deposited by vapor-depositing the hard coating layers under conditions that deviate from the manufacturing conditions of the inventive coated tools 1 to 13. Were manufactured respectively.
  • the conditions a to d shown in Table 5 are required for forming the TiCN layer of the lower layer.
  • a TiCN layer shown in Table 7 was formed by vapor deposition.
  • At least one TiCN layer of the lower layers is formed by using a field emission scanning electron microscope and a constituent atomic shared lattice distribution graph.
  • a constituent atomic shared lattice distribution graph is set in a lens barrel of a field emission scanning electron microscope with the longitudinal section of the lower TiCN layer as a polished surface, and incident at 70 degrees on the polished surface.
  • An electron beam with an accelerating voltage of 15 kV at an angle is irradiated at an irradiation current of 1 nA to individual crystal grains existing in the measurement range of the vertical cross-section polished surface, and an electron backscatter diffraction image apparatus is used to divide the region of 30 ⁇ 50 ⁇ m.
  • the inclination angle formed by the normal lines of the (001) plane and (011) plane, which are crystal planes of the crystal grains, is measured with respect to the normal line of the tool base surface.
  • grain boundary length of the constituent atomic shared lattice point form (unit form) of ⁇ 31 or more a value obtained by subtracting the total grain boundary length from ⁇ 3 to ⁇ 29 from the total grain boundary length of ⁇ 3 or more obtained by measurement. The total of grain boundary lengths of ⁇ 31 or more was obtained.
  • the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 31 or more in the lower TiCN layer becomes the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 or more.
  • Occupancy ratio, grain boundary length of constituent atom shared lattice point form (unit form) of ⁇ 3, proportion of grain boundary length of constituent atom shared lattice point form (unit form) of ⁇ 3 to ⁇ 29, and composition of ⁇ 5 Tables 8 and 9 show the ratio of the grain boundary length of the atomic shared lattice point form (unit form) to the grain boundary length of the constituent atomic shared lattice point form (unit form) of ⁇ 3 to ⁇ 29.
  • FIG. 1 shows that the grain boundary length of the constituent atom shared lattice point form (unit form) which is ⁇ 31 or more occupies 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) which is ⁇ 3 or more.
  • the example of the constituent atom shared lattice point distribution graph of the TiCN layer of the invention coated tool 1 is shown.
  • FIG. 2 shows a constituent atomic shared lattice in which the proportion of the grain boundary length of each constituent atomic shared lattice point form (unit form) in the corresponding grain boundary length of ⁇ 3 to ⁇ 29 of the TiCN layer of the coated tool 1 of the present invention is shown.
  • a point distribution graph is shown.
  • FIG. 3 shows that the grain boundary length of the constituent atom shared lattice point form (unit form) that is ⁇ 31 or more occupies 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) that is ⁇ 3 or more.
  • An example of the constituent atomic shared lattice point distribution graph of the TiCN layer of the invention-coated tool 2 is shown. As shown in FIG.
  • the grain boundary of the constituent atomic shared lattice point form (unit form) of ⁇ 3 of the inventive coated tool 2 The length is 20% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 to ⁇ 29, and the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 5 is ⁇ 3 to It can be seen that it is 30% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 29.
  • the TiCN layer of the lower layer of the coated tool of the present invention has a constituent atom shared lattice point form in which the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 31 or more is ⁇ 3 or more ( 80% or more of the grain boundary length of the unit form), and in some cases, the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 3 is the constituent atom shared lattice point form of ⁇ 3 to ⁇ 29 ( Grains having a grain boundary length of ⁇ 3 to ⁇ 29 that are 20% or less of the grain boundary length of (unit form) and the grain boundary length of the constituent atom shared lattice point form (unit form) of ⁇ 5 It was 30% or less of the field length.
  • the thicknesses of the constituent layers of the hard coating layers of the coated tools 1 to 13 of the present invention and the comparative coated tools 1 to 13 were measured longitudinally using a scanning electron microscope. The same average layer thickness (average value of 5-point measurement) was shown. Tables 6 to 9 show the results.
  • the maximum particle width W and the maximum particle length L are measured for each TiCN crystal grain existing in the region of the height of the TiCN layer in the direction perpendicular to the tool substrate, the distribution is calculated, and the maximum particle width is calculated. A value indicating the maximum peak of the W distribution was calculated.
  • the value of the aspect ratio L / W was determined for each of the TiCN crystal grains, and the area ratio of the crystal grains having an aspect ratio L / W of 3 or more in the longitudinal section of the TiCN layer was determined. Tables 8 and 9 show the results.
  • cutting condition A a wet high-speed intermittent high-cut cutting test of stainless steel (normal cutting speed and cutting are 70 m / min and 2.0 mm, respectively), Work material: JIS / S60C lengthwise equidistant 4 grooves, Cutting speed: 300 m / min, Incision: 1.5mm, Feed: 1.0mm / rev, Cutting time: 5 minutes
  • cutting condition B a wet high-speed intermittent high-feed cutting test of high-carbon steel (normal cutting speed and feed amount are 100 m / min and 0.3 mm /
  • the coated tools 1 to 13 of the present invention have excellent chipping resistance because the TiCN layer of the lower layer has excellent toughness, and excellent cutting performance over a long period of use. It was. On the other hand, it is apparent that the comparative coated tools 1 to 13 reach the service life in a relatively short time due to the occurrence of chipping and peeling of the hard coating layer in high-speed intermittent heavy cutting.
  • the coated tool of the present invention is capable of chipping and peeling the hard coating layer even under severe cutting conditions such as high-speed, high-cutting and high-feed heavy cutting such as carbon steel and stainless steel in which a high load acts on the cutting edge. Since it exhibits excellent cutting performance over a long period of use, it is fully satisfactory for higher performance of cutting equipment, labor saving and energy saving of cutting, and cost reduction. It can be done.

Abstract

The purpose of the present invention is to provide a surface-coated cutting tool exhibiting excellent chipping resistance and peeling resistance under a deep-cut, fast-feed, high-speed intermittent heavy cutting condition in which a heavy load acts on the cutting edge. The present invention provides a surface-coated cutting tool in which a lower layer comprising a Ti compound layer including at least one TiCN layer and an upper layer comprising an α-Al2O3 layer are formed on a tool body surface, wherein when a distribution ratio of constituent atom sharing lattice point structures(units) of adjoining TiCN crystal grains in the TiCN layer is calculated using a field emission type scanning electron microscope and an electron backscatter diffraction imaging device, the grain boundary length for constituent atom sharing lattice point structures (units) of Σ31 and makes up at least 80% of the total grain boundary length of constituent atom sharing lattice point structures (units) of Σ3 and higher, and the area ratio of TiCN crystal grains having an aspect ratio of 3 or higher is 80% or higher.

Description

硬質被覆層がすぐれた耐チッピング性を発揮する表面被覆切削工具Surface coated cutting tool with excellent chipping resistance due to hard coating layer
　本発明は、鋼やステンレス鋼等の切削加工を、切刃に高負荷が作用する高速断続高切り込み条件および高速断続高送り条件で行った場合でも、硬質被覆層がすぐれた耐チッピング性を発揮し、長期に亘ってすぐれた切削性能を発揮する表面被覆切削工具（以下、被覆工具という）に関する。 The present invention demonstrates excellent chipping resistance even when cutting steel or stainless steel under high-speed intermittent high-cutting conditions and high-speed intermittent high-feed conditions where a high load acts on the cutting blade. The present invention also relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent cutting performance over a long period of time.
　従来、一般に、炭化タングステン（以下、ＷＣで示す）基超硬合金または炭窒化チタン（以下、ＴｉＣＮで示す）基サーメットで構成された基体（以下、これらを総称して工具基体という）の表面に、
（ａ）下部層が、Ｔｉの炭化物（以下、ＴｉＣで示す）層、窒化物（以下、同じくＴｉＮで示す）層、炭窒化物（以下、ＴｉＣＮで示す）層、炭酸化物（以下、ＴｉＣＯで示す）層、および炭窒酸化物（以下、ＴｉＣＮＯで示す）層のうちの１層または２層以上からなるＴｉ化合物層、
（ｂ）上部層が、化学蒸着した状態でα型の結晶構造を有する酸化アルミニウム層（以下、Ａｌ２Ｏ３層で示す）、
以上（ａ）および（ｂ）で構成された硬質被覆層が蒸着形成された被覆工具が知られている。 Conventionally, generally on the surface of a substrate (hereinafter collectively referred to as a tool substrate) composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet. ,
(A) The lower layer is a Ti carbide (hereinafter referred to as TiC) layer, a nitride (hereinafter also referred to as TiN) layer, a carbonitride (hereinafter referred to as TiCN) layer, a carbon oxide (hereinafter referred to as TiCO). And a Ti compound layer composed of one or more of a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) an aluminum oxide layer (hereinafter, referred to as an Al 2 O 3 layer) having an α-type crystal structure in a state where the upper layer is chemically vapor-deposited;
A coated tool in which the hard coating layer constituted by (a) and (b) is formed by vapor deposition is known.
　しかし、前述したような従来の被覆工具は、例えば、各種の鋼や鋳鉄などの連続切削ではすぐれた切削性能を発揮するが、これを、断続切削加工に用いた場合には、被覆層のチッピングが発生しやすく、工具寿命が短命になるという問題があった。
　そこで、被覆層の耐チッピング性を高めるために、硬質被覆層に種々の改良を加えた被覆工具が提案されている。 However, the conventional coated tools as described above exhibit excellent cutting performance in continuous cutting of, for example, various types of steel and cast iron. When this is used for intermittent cutting, chipping of the coating layer is performed. There is a problem that tool life tends to occur and the tool life is shortened.
Therefore, in order to improve the chipping resistance of the coating layer, a coating tool in which various improvements are added to the hard coating layer has been proposed.
　例えば、特許文献１には、
工具基体の表面に、
（ａ）下部層が、いずれも化学蒸着形成された、Ｔｉの炭化物層、窒化物層、炭窒化物層、炭酸化物層、および炭窒酸化物層のうちの２層以上からなり、かつ３～２０μｍの合計平均層厚を有するＴｉ化合物層、
（ｂ）上部層が、化学蒸着形成された、１～１５μｍの平均層厚を有する酸化アルミニウム層、
以上（ａ）および（ｂ）で構成された硬質被覆層を形成してなる被覆工具において、
上記（ａ）のＴｉ化合物層のうちの１層を、
　反応ガス組成：容量％で、ＴｉＣｌ４：０．１～０．８％、ＣＨ３ＣＮ：０．０５～０．３％、Ａｒ：１０～３０％、Ｈ２：残り、
　反応雰囲気温度：９３０～１０００℃、
　反応雰囲気圧力：６～２０ｋＰａ、
の条件で、２．５～１５μｍの平均層厚に化学蒸着形成してなると共に、
　電界放出型走査電子顕微鏡を用い、表面研磨面の測定範囲内に存在する結晶粒個々に電子線を照射し、電子後方散乱回折像装置を用いて、所定領域を０．１μｍ／ｓｔｅｐの間隔で、前記表面研磨面の法線に対する、前記結晶粒の結晶面である（００１）面および（０１１）面の法線がなす傾斜角を測定し、この場合前記結晶粒は、格子点にＴｉ、炭素、および窒素からなる構成原子がそれぞれ存在するＮａＣｌ型立方晶の結晶構造を有し、この結果得られた測定傾斜角に基づいて、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出すると共に、前記構成原子共有格子点間に存在する構成原子を共有しない格子点の数：Ｎ（この場合、ＮはＮａＣｌ型立方晶の結晶構造上２以上の偶数となるが、分布頻度の点からＮ：２８を上限とする）毎に定めたΣＮ＋１で表される構成原子共有格子点形態（単位形態）のそれぞれの分布割合を算出し、Σ３～Σ２９のそれぞれの構成原子共有格子点形態（単位形態）の分布割合を、前記Σ３～Σ２９の構成原子共有格子点形態（単位形態）全体の合計分布割合に占める割合で示す構成原子共有格子点分布グラフにおいて、Σ３に最高ピークが存在し、かつ前記Σ３の分布割合が前記構成原子共有格子点形態（単位形態）全体の合計分布割合の６５～８０％を占める構成原子共有格子点分布グラフを示す炭窒化チタン層、からなる被覆工具が提案されており、この被覆工具によれば、鋼や鋳鉄などの高速断続切削加工で、硬質被覆層がすぐれた耐チッピング性を発揮するとされている。 For example, Patent Document 1 discloses that
On the surface of the tool base,
(A) The lower layer is composed of two or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride layer, all formed by chemical vapor deposition, and 3 A Ti compound layer having a total average layer thickness of ˜20 μm,
(B) an aluminum oxide layer having an average layer thickness of 1 to 15 μm, wherein the upper layer is formed by chemical vapor deposition;
In the coated tool formed by forming the hard coating layer composed of (a) and (b) above,
One layer of the Ti compound layer of the above (a),
Reaction gas composition: volume%, TiCl 4 : 0.1 to 0.8%, CH 3 CN: 0.05 to 0.3%, Ar: 10 to 30%, H 2 : remaining,
Reaction atmosphere temperature: 930 to 1000 ° C.,
Reaction atmosphere pressure: 6-20 kPa,
Under the conditions, chemical vapor deposition is formed to an average layer thickness of 2.5 to 15 μm,
Using a field emission scanning electron microscope, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, and an electron backscatter diffraction image apparatus is used to set a predetermined region at an interval of 0.1 μm / step. , The inclination angle formed by the normal lines of the (001) plane and the (011) plane, which are the crystal planes of the crystal grains, with respect to the normal line of the surface-polished surface is measured. Each of the constituent atoms has an NaCl-type cubic crystal structure in which constituent atoms composed of carbon and nitrogen are present, and each of the constituent atoms is formed at the interface between adjacent crystal grains based on the measured tilt angle. Calculates the distribution of lattice points that share one constituent atom among the crystal grains (constituent atom shared lattice points), and the number of lattice points that do not share the constituent atoms that exist between the constituent atom shared lattice points: N (in this case N is Each of the constituent atomic shared lattice point forms (unit forms) represented by ΣN + 1 defined for each of the even number of 2 or more on the crystal structure of the aCl type cubic crystal, with N: 28 being the upper limit in terms of distribution frequency) The distribution ratio of each constituent atom shared lattice point form (unit form) of Σ3 to Σ29 is accounted for in the total distribution ratio of the constituent atom shared lattice point forms (unit form) of Σ3 to Σ29. In the constituent atomic shared lattice point distribution graph expressed as a ratio, the highest peak exists in Σ3, and the distribution ratio of Σ3 occupies 65 to 80% of the total distribution ratio of the constituent atomic shared lattice point form (unit form) A coated tool composed of a titanium carbonitride layer showing a constituent atomic share lattice point distribution graph has been proposed. According to this coated tool, a high resistance to chipping with a hard coating layer can be achieved by high-speed intermittent cutting of steel or cast iron. It has been to exert a ring of.
　また、特許文献２には、
工具基体の表面に、
（ａ）下部層が、いずれも化学蒸着形成された、チタンの炭化物層、窒化物層、炭窒化物層、炭酸化物層、および炭窒酸化物層のうちの２層以上からなり、かつ、その内の１層はチタンの炭窒化物層からなり、３～２０μｍの合計平均層厚を有するチタン化合物層、
（ｂ）上部層が、化学蒸着形成された、１～１５μｍの平均層厚を有する酸化アルミニウム層、
以上（ａ）および（ｂ）で構成された硬質被覆層を形成してなる被覆工具において、
　上記（ａ）のチタン化合物層の内のチタンの炭窒化物層について、電界放出型走査電子顕微鏡を用い、縦断面の測定範囲内に存在する結晶粒個々に電子線を照射し、電子後方散乱回折像装置を用いて、所定領域を０．１μｍ／ｓｔｅｐの間隔で、基体表面の法線に対する、前記結晶粒の結晶面である（００１）面および（０１１）面の法線がなす傾斜角を測定し、この場合、前記結晶粒は、格子点にＴｉ、炭素、および窒素からなる構成原子がそれぞれ存在するＮａＣｌ型面心立方晶の結晶構造を有し、この結果得られた測定傾斜角に基づいて、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出すると共に、前記構成原子共有格子点間に存在する構成原子を共有しない格子点の数Ｎ（この場合、ＮはＮａＣｌ型立方晶の結晶構造上２以上の偶数となるが、分布頻度の点からＮ＝２８を上限とする）毎に定めたΣＮ＋１で表される構成原子共有格子点形態（単位形態）のそれぞれの分布割合を算出し、Σ３～Σ２９のそれぞれの構成原子共有格子点形態（単位形態）の分布割合を、前記Σ３～Σ２９の構成原子共有格子点形態（単位形態）全体の合計分布割合に占める割合で示す構成原子共有格子点分布グラフにおいて、切れ刃稜線部では前記Σ３の分布割合が前記構成原子共有格子点形態（単位形態）全体の合計分布割合の５～１３％を示し、切れ刃稜線部以外の領域では前記Σ３の分布割合が前記構成原子共有格子点形態（単位形態）全体の合計分布割合の５０％以上を占める構成原子共有格子点分布グラフを示すチタンの炭窒化物層、
からなる強断続加工ですぐれた耐チッピング性を発揮する被覆工具が提案されており、この被覆工具によれば、切れ刃稜線部の硬質被覆層の下部層のΣ３の分布割合と、切れ刃稜線部以外の領域における硬質被覆層の下部層のΣ３の分布割合を、それぞれ、特定の範囲に定めることによって、断続の間隔が長く切れ刃先端には強い衝撃が加わる強断続加工において、耐摩耗性の低下を招くことなく、すぐれた耐チッピング性が発揮されるとされている。 In addition, in Patent Document 2,
On the surface of the tool base,
(A) the lower layer is composed of two or more of titanium carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer, all formed by chemical vapor deposition; and One of them is a titanium compound layer comprising a titanium carbonitride layer and having a total average layer thickness of 3 to 20 μm,
(B) an aluminum oxide layer having an average layer thickness of 1 to 15 μm, wherein the upper layer is formed by chemical vapor deposition;
In the coated tool formed by forming the hard coating layer composed of (a) and (b) above,
For the titanium carbonitride layer in the titanium compound layer of (a) above, using a field emission scanning electron microscope, each crystal grain present within the measurement range of the longitudinal section is irradiated with an electron beam, and electron backscattering is performed. Using a diffraction image apparatus, the inclination angle formed by the normal lines of the (001) plane and the (011) plane, which are the crystal planes of the crystal grains, with respect to the normal line of the substrate surface at predetermined intervals of 0.1 μm / step In this case, the crystal grains have a NaCl-type face-centered cubic crystal structure in which constituent atoms composed of Ti, carbon, and nitrogen are present at lattice points, respectively. And calculating the distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains, and Between atomic lattice points The number of lattice points that do not share the constituent atoms to be determined is determined for each N (in this case, N is an even number of 2 or more in the crystal structure of the NaCl type cubic crystal, but N = 28 is the upper limit in terms of distribution frequency). The distribution ratios of the constituent atom shared lattice point forms (unit forms) represented by ΣN + 1 are calculated, and the distribution ratios of the constituent atom shared lattice point forms (unit forms) of Σ3 to Σ29 are calculated as Σ3 to Σ29. In the constituent atomic shared lattice point distribution graph showing the proportion of the total constituent distribution of constituent atomic shared lattice points (unit form) in the total distribution ratio, the distribution ratio of Σ3 is the constituent atomic shared lattice point form (unit form) at the cutting edge ridge line portion. ) 5 to 13% of the total distribution ratio of the whole, and in the region other than the cutting edge ridge line, the distribution ratio of Σ3 accounts for 50% or more of the total distribution ratio of the constituent atom shared lattice point form (unit form) Constituent Carbonitride layer of titanium that shows the sharing lattice point distribution graph,
A coating tool that exhibits excellent chipping resistance in a strong interrupted machining is proposed. According to this coating tool, the distribution ratio of Σ3 in the lower layer of the hard coating layer of the cutting edge ridge line and the cutting edge ridge line Wear resistance in hard interrupted processing where the interrupting interval is long and a strong impact is applied to the cutting edge tip by setting the distribution ratio of Σ3 of the lower layer of the hard coating layer in a region other than the part to a specific range, respectively. It is said that excellent chipping resistance is exhibited without incurring a decrease in the thickness.
特許第４５１８２５８号公報Japanese Patent No. 4518258 特開２０１５－１８２１５４号公報JP2015-182154A
　近年の切削装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求は強い。これに伴い、切削加工は一段と高速化すると共に、高切り込みや高送りなどの重切削、断続切削等で切刃に高負荷が作用する傾向にある。
前述した従来の被覆工具を鋼や鋳鉄などの通常の条件での連続切削、断続切削に用いた場合には特に問題はないが、より一段と厳しい切削条件である高速断続重切削条件で鋼やステンレス鋼を加工した場合には、硬質被覆層の塑性変形性が十分でないことに加え、硬質被覆層には高負荷が作用するため、硬質被覆層を構成する粒子の脱落、剥離等の発生あるいはチッピングの発生を原因として比較的短時間で工具寿命に至る。 In recent years, the performance of cutting machines has been remarkably improved. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting. Along with this, cutting speed is further increased, and a high load tends to be applied to the cutting edge due to heavy cutting such as high cutting and high feed, and intermittent cutting.
There is no particular problem when the above-mentioned conventional coated tools are used for continuous cutting and interrupted cutting under normal conditions such as steel and cast iron, but steel and stainless steel are used under high-speed interrupted heavy cutting conditions, which are more severe cutting conditions. When steel is processed, the hard coating layer is not sufficiently plastically deformable, and a high load acts on the hard coating layer. The tool life is reached in a relatively short time due to the occurrence of.
　そこで、本発明者らは、前述のような観点から、切れ刃に断続的・衝撃的な高負荷が作用し、また、硬質被覆層の塑性変形が発生しやすい高速断続重切削条件（例えば、高速高切り込み断続切削条件、高速高送り断続切削条件）で使用した場合でも、硬質被覆層の剥離、チッピングが発生しないような硬質被覆層の構造について鋭意研究を行ったところ、硬質被覆層の下部層を構成する少なくとも一つのＴｉＣＮ層において、該ＴｉＣＮ層の全対応粒界長に対して、Σ３１以上の対応粒界長の長さ割合を８０％以上とすることによって、下部層を構成するＴｉＣＮ層中に靱性の高い粒界を多く分布させることができ、これにより、切刃に断続的・衝撃的な高負荷が作用する高速高切り込み断続条件あるいは高速高送り断続条件で鋼、ステンレス鋼等を切削加工した場合にも、硬質被覆層の剥離、チッピングの発生が抑制されることを見出した。 Therefore, from the viewpoints described above, the present inventors are subjected to intermittent and shocking high loads on the cutting edge, and high-speed intermittent heavy cutting conditions in which plastic deformation of the hard coating layer is likely to occur (for example, Even when used under high-speed, high-cut high-intermittent cutting conditions and high-speed, high-feed intermittent cutting conditions), the hard coating layer structure that does not cause peeling or chipping of the hard coating layer has been studied. In at least one TiCN layer constituting the layer, the length ratio of the corresponding grain boundary length of Σ31 or more to the total corresponding grain boundary length of the TiCN layer is set to 80% or more, thereby forming the TiCN constituting the lower layer Grain boundaries with high toughness can be distributed in the layer, which makes it possible to produce steel, stainless steel under high-speed, high-cut and high-feed intermittent conditions where intermittent and impactful high loads are applied to the cutting edge. When cutting a scan steel also, peeling of the hard coating layer, generation of chipping was found to be suppressed.
　本発明は、前記知見に基づいてなされたものであって、
「（１）炭化タングステン基超硬合金または炭窒化チタン基サーメットで構成された工具基体の表面に下部層と上部層からなる硬質被覆層が設けられている表面被覆切削工具において、
（ａ）前記下部層は、３～２０μｍの合計平均層厚を有し、ＴｉＣ、ＴｉＮ、ＴｉＣＮ、ＴｉＣＯ、ＴｉＣＮＯのうちの1層または２層以上からなるＴｉ化合物層であって、その内の少なくとも１層はＴｉＣＮ層で構成されており、
（ｂ）前記上部層は、１～１５μｍの平均層厚を有し、α型の結晶構造を有するＡｌ２Ｏ３層からなり、
（ｃ）前記下部層の少なくとも１層のＴｉＣＮ層について、電界放出型走査電子顕微鏡を用い、前記少なくとも１層のＴｉＣＮ層の縦断面の測定範囲内に存在する結晶粒個々に電子線を照射し、電子後方散乱回折像装置を用いて、所定領域を０．１μｍ／ｓｔｅｐの間隔で、基体表面の法線に対する、前記結晶粒の結晶面である（００１）面および（０１１）面の法線がなす傾斜角を測定し、この場合前記結晶粒は、格子点にＴｉ、炭素、および窒素からなる構成原子がそれぞれ存在するＮａＣｌ型面心立方晶の結晶構造を有し、この結果得られた測定傾斜角に基づいて、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出すると共に、前記構成原子共有格子点間に存在する構成原子を共有しない格子点の数Ｎ毎に定めたΣＮ＋１で表される構成原子共有格子点形態（単位形態）のそれぞれの分布割合を算出した場合に、全対応粒界長に占める各構成原子共有格子点からなる対応粒界長の割合が示された対応粒界分布グラフにおいて、Σ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％を占め、
（ｄ）前記少なくとも１層のＴｉＣＮ層の縦断面において、アスペクト比が３以上であるＴｉＣＮ結晶粒が８０％以上の面積割合を占めることを特徴とする表面被覆切削工具。
　（２）前記下部層の少なくとも１層のＴｉＣＮ層について、電界放出型走査電子顕微鏡を用い、前記少なくとも１層のＴｉＣＮ層の縦断面の測定範囲内に存在する結晶粒個々に電子線を照射し、電子後方散乱回折像装置を用いて、所定領域を０．１μｍ／ｓｔｅｐの間隔で、基体表面の法線に対する、前記結晶粒の結晶面である（００１）面および（０１１）面の法線がなす傾斜角を測定し、この場合前記結晶粒は、格子点にＴｉ、炭素、および窒素からなる構成原子がそれぞれ存在するＮａＣｌ型面心立方晶の結晶構造を有し、この結果得られた測定傾斜角に基づいて、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出すると共に、前記構成原子共有格子点間に存在する構成原子を共有しない格子点の数Ｎ毎に定めたΣＮ＋１で表される構成原子共有格子点形態（単位形態）のそれぞれの分布割合を算出した場合に、Σ３の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の２０％以下であり、また、Σ５の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の３０％以下であることを特徴とする前記（１）に記載の表面被覆切削工具。」 The present invention has been made based on the above findings,
“(1) In a surface-coated cutting tool in which a hard coating layer composed of a lower layer and an upper layer is provided on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
(A) The lower layer is a Ti compound layer having a total average layer thickness of 3 to 20 μm and comprising one or more of TiC, TiN, TiCN, TiCO, and TiCNO, At least one layer is composed of a TiCN layer,
(B) the upper layer comprises an Al 2 O 3 layer having an average layer thickness of 1 to 15 μm and having an α-type crystal structure;
(C) At least one TiCN layer of the lower layer is irradiated with an electron beam on each crystal grain existing within the measurement range of the longitudinal section of the at least one TiCN layer using a field emission scanning electron microscope. Then, using an electron backscatter diffraction image apparatus, the normal areas of the (001) plane and (011) plane, which are crystal planes of the crystal grains, with respect to the normal line of the substrate surface with respect to the normal line of the predetermined region at an interval of 0.1 μm / step In this case, the crystal grains have a NaCl type face-centered cubic crystal structure in which constituent atoms composed of Ti, carbon, and nitrogen are present at lattice points, respectively. Based on the measured tilt angle, the distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains is calculated. Together with the above When the distribution ratio of each constituent atom shared lattice point form (unit form) represented by ΣN + 1 determined for each number N of lattice points that do not share constituent atoms existing between the shared atomic lattice points is calculated, In the corresponding grain boundary distribution graph in which the proportion of the corresponding grain boundary length composed of each constituent atom shared lattice point in the corresponding grain boundary length is shown, the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ31 or more is Occupy 80% of the grain boundary length of the constituent atomic shared lattice point form (unit form) which is Σ3 or more,
(D) A surface-coated cutting tool characterized in that, in the longitudinal section of the at least one TiCN layer, TiCN crystal grains having an aspect ratio of 3 or more occupy an area ratio of 80% or more.
(2) At least one TiCN layer of the lower layer is irradiated with an electron beam on each crystal grain existing within the measurement range of the longitudinal section of the at least one TiCN layer using a field emission scanning electron microscope. Then, using an electron backscatter diffraction image apparatus, the normal areas of the (001) plane and (011) plane, which are crystal planes of the crystal grains, with respect to the normal line of the substrate surface with respect to the normal line of the predetermined region at an interval of 0.1 μm / step In this case, the crystal grains have a NaCl type face-centered cubic crystal structure in which constituent atoms composed of Ti, carbon, and nitrogen are present at lattice points, respectively. Based on the measured tilt angle, the distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains is calculated. Together with the above When the distribution ratio of each constituent atom shared lattice point form (unit form) represented by ΣN + 1 determined for each number N of lattice points that do not share constituent atoms existing between the shared atomic lattice points is calculated as Σ3 The grain boundary length of the constituent atomic shared lattice point form (unit form) of is not more than 20% of the grain boundary length of the constituent atomic shared lattice point form (unit form) of Σ3 to Σ29, and the constituent atomic shared lattice of Σ5 The surface coating according to (1) above, wherein the grain boundary length of the point form (unit form) is 30% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 to Σ29 Cutting tools. "
　次に、本発明の被覆工具について詳細に説明する。
下部層：
　下部層を構成するＴｉ化合物層は、ＴｉＣ層、ＴｉＮ層、ＴｉＣＮ層、ＴｉＣＯ層およびＴｉＣＮＯ層のうちの1層または２層以上からなり（ただし、その内の少なくとも１層はＴｉＣＮ層）、基本的にはα型の結晶構造を有するＡｌ２Ｏ３層（以下、「α－Ａｌ２Ｏ３層」で示す。）の下部層として存在し、自身の持つすぐれた高温強度によって、硬質被覆層に対して高温強度を与える。さらに、Ｔｉ化合物層は、工具基体表面、α－Ａｌ２Ｏ３層からなる上部層のいずれにも密着し、硬質被覆層の工具基体に対する密着性を維持する作用を有する。
しかしながら、このＴｉ化合物層の合計平均層厚が３μｍ未満である場合、前述した作用を十分に発揮させることができない。一方、このＴｉ化合物層の合計平均層厚が２０μｍを越える場合、高速断続重切削では熱塑性変形を起し易くなり、偏摩耗の原因となる。
したがって、Ｔｉ化合物層の合計平均層厚は３～２０μｍと定めた。 Next, the coated tool of the present invention will be described in detail.
Lower layer:
The Ti compound layer constituting the lower layer is composed of one or more of TiC layer, TiN layer, TiCN layer, TiCO layer and TiCNO layer (however, at least one of them is a TiCN layer). Specifically, the hard coating layer exists as a lower layer of an Al 2 O 3 layer having an α-type crystal structure (hereinafter referred to as “α-Al 2 O 3 layer”), and has a high temperature strength possessed by itself. High temperature strength is given to. Further, the Ti compound layer is in close contact with both the tool base surface and the upper layer composed of the α-Al 2 O 3 layer, and has an action of maintaining the adhesion of the hard coating layer to the tool base.
However, when the total average layer thickness of the Ti compound layer is less than 3 μm, the above-described action cannot be sufficiently exhibited. On the other hand, when the total average layer thickness of the Ti compound layer exceeds 20 μm, high-speed intermittent heavy cutting tends to cause thermoplastic deformation, which causes uneven wear.
Therefore, the total average layer thickness of the Ti compound layer is determined to be 3 to 20 μm.
下部層のうちの少なくとも１層のＴｉＣＮ層：
　本発明における下部層は、少なくとも１層のＴｉＣＮ層を含む。
　そして、前記少なくとも１層のＴｉＣＮ層について、構成原子共有格子点分布グラフを求めた場合、Σ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％以上を占めることが重要である。
　Σ３１以上の構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％以上を占める場合には、ＴｉＣＮ層中に靱性にすぐれた粒界が数多く分布することによって、ＴｉＣＮ層の衝撃緩和性が向上し、また、工具基体の変形に追従して硬質被覆層が変形することが可能となるため、鋼、ステンレス鋼等の高速断続重切削加工において、チッピングの発生が抑制される。
　図１に、Σ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％以上を占めるＴｉＣＮ層の構成原子共有格子点分布グラフの例を示す。 At least one TiCN layer of the lower layer:
The lower layer in the present invention includes at least one TiCN layer.
When the constituent atom sharing lattice point distribution graph is obtained for the at least one TiCN layer, the constituent atom sharing in which the grain boundary length of the constituent atom sharing lattice point form (unit form) is Σ31 or more is Σ3 or more. It is important to occupy 80% or more of the grain boundary length in the lattice point form (unit form).
When the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ31 or more occupies 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 or more, in the TiCN layer Since many grain boundaries with excellent toughness are distributed, the impact relaxation properties of the TiCN layer are improved and the hard coating layer can be deformed following the deformation of the tool base. In high-speed intermittent heavy cutting of steel or the like, occurrence of chipping is suppressed.
In FIG. 1, the TiCN layer occupying 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) in which the constituent atom shared lattice point form (unit form) is Σ3 or more. An example of the constituent atom shared lattice point distribution graph of is shown.
　さらに、Σ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％以上を占める前記ＴｉＣＮ層において、Σ３の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の２０％以下であり、また、Σ５の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の３０％以下である場合には、ＴｉＣＮ層の靱性がより向上するため、一段とすぐれた耐チッピング性が発揮される。
　図２に、Σ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％以上を占め、さらに、Σ３の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の２０％以下であり、かつ、Σ５の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の３０％以下であるＴｉＣＮ層の構成原子共有格子点分布グラフの例を示す。 Furthermore, in the TiCN layer in which the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ31 or more occupies 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ3 or more , The grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 is 20% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 to Σ29, and the constituent atom of Σ5 When the grain boundary length of the shared lattice point form (unit form) is 30% or less of the grain boundary length of the constituent atomic shared lattice form (unit form) of Σ3 to Σ29, the toughness of the TiCN layer is further improved. For this reason, excellent chipping resistance is exhibited.
In FIG. 2, the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ31 or more occupies 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ3 or more, , The grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 is 20% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 to Σ29, and the constituent atom of Σ5 Example of constituent atomic shared lattice point distribution graph of TiCN layer in which the grain boundary length of the shared lattice point form (unit form) is 30% or less of the grain boundary length of the constituent atomic shared lattice point form (unit form) of Σ3 to Σ29 Indicates.
　ここで、構成原子共有格子点分布グラフは、この出願前から既によく知られているように、電界放出型走査電子顕微鏡を用い、例えば、硬質被覆層の下部層の層厚方向に平行な縦断面の測定範囲内に存在する結晶粒個々に電子線を照射し、電子後方散乱回折像装置を用いて、所定領域を０．１μｍ／ｓｔｅｐの間隔で、前記表面研磨面の法線に対する、前記結晶粒の結晶面である（００１）面および（０１１）面の法線がなす傾斜角を測定し（この場合、前記結晶粒は、格子点にＴｉ、炭素、および窒素からなる構成原子がそれぞれ存在するＮａＣｌ型面心立方晶の結晶構造を有する炭窒化チタン結晶粒である）、この結果得られた測定傾斜角に基づいて、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出すると共に、前記構成原子共有格子点間に存在する構成原子を共有しない格子点の数Ｎ（この場合、ＮはＮａＣｌ型面心立方晶の結晶構造上２以上の偶数となる。）毎に定めたΣＮ＋１で表される構成原子共有格子点形態（単位形態）のそれぞれの粒界長を算出し、Σ３以上のそれぞれの構成原子共有格子点形態（単位形態）の粒界長を、Σ３以上の構成原子共有格子点形態（単位形態）の合計粒界長に占める割合で示す構成原子共有格子点分布グラフを作成する。
　なお、Σ３１以上の粒界長の合計は、Σ３１以上の個々のＮにおける粒界長を算出するのではなく、Σ３１以上としてひとまとめにした。すなわち、Σ３、Σ５、Σ７、Σ９、Σ１１、Σ１３、Σ１５、Σ１７、Σ１９、Σ２１、Σ２３、Σ２５、Σ２７、Σ２９のそれぞれの粒界長を算出し、測定により得られたΣ３以上の全粒界長からΣ３～Σ２９までの粒界長の合計を差し引いた値をΣ３１以上の粒界長の合計として求めた。 Here, as already well known before this application, the constituent atomic shared lattice distribution graph is obtained by using a field emission scanning electron microscope, for example, a longitudinal section parallel to the layer thickness direction of the lower layer of the hard coating layer. The crystal grains existing within the measurement range of the surface are irradiated with an electron beam, and the electron backscatter diffraction image apparatus is used to divide the predetermined region at a distance of 0.1 μm / step with respect to the normal line of the surface polished surface. The inclination angle formed by the normal lines of the (001) plane and the (011) plane, which are crystal planes of the crystal grains, is measured (in this case, each of the crystal grains has constituent atoms composed of Ti, carbon, and nitrogen at lattice points. Each of the above-mentioned constituent atoms at the interface between the adjacent crystal grains based on the measurement tilt angle obtained as a result. One between the grains The distribution of lattice points that share constituent atoms (constituent atom shared lattice points) is calculated, and the number N of lattice points that do not share constituent atoms existing between the constituent atom shared lattice points (in this case, N is a NaCl-type surface) It is an even number of 2 or more in terms of the crystal structure of the centered cubic crystal.) Each grain boundary length of the constituent atom shared lattice point form (unit form) represented by ΣN + 1 defined for each is calculated, and each structure of Σ3 or more A constituent atomic shared lattice point distribution graph is created that shows the grain boundary length of the atomic shared lattice point form (unit form) as a percentage of the total grain boundary length of the constituent atomic shared lattice form (unit form) of Σ3 or more.
Note that the sum of the grain boundary lengths of Σ31 or more was grouped as Σ31 or more instead of calculating the grain boundary length in each N of Σ31 or more. That is, the grain boundary lengths of Σ3, Σ5, Σ7, Σ9, Σ11, Σ13, Σ15, Σ17, Σ19, Σ21, Σ23, Σ25, Σ27, and Σ29 are calculated, and all grain boundaries greater than or equal to Σ3 obtained by measurement A value obtained by subtracting the total grain boundary length from Σ3 to Σ29 from the length was obtained as the total grain boundary length of Σ31 or more.
　前記のΣ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％以上を占めるＴｉＣＮ層を有する下部層は、例えば、以下のようにして形成することができる。
　即ち、まず、工具基体表面に、通常の化学蒸着装置を使用して、ＴｉＣ層、ＴｉＮ層、ＴｉＣＮ層、ＴｉＣＯ層およびＴｉＣＮＯ層のうちの１層または２層以上からなるＴｉ化合物層を硬質被覆層の下部層として蒸着形成する（なお、ＴｉＣＮ層のみを蒸着形成することも勿論可能である）。
そして、上記下部層のうちの少なくとも１層のＴｉＣＮ層については、
　反応ガス組成（容量％）：ＴｉＣｌ４　１～３％、ＣＨ３ＣＮ　０．３～１．０％、Ｎ２　２５～６０％、ＨＣｌ　０．０５％～０．２％、Ａｒ　３～１５％、残部Ｈ２、
　反応雰囲気温度：７５０～９００℃、
　反応雰囲気圧力：５～１０ｋＰａ、
の条件で化学蒸着することにより、前記所定の構成原子共有格子点形態（単位形態）を有するＴｉＣＮ層を形成することができる。 The grain boundary length of the constituent atom shared lattice point form (unit form) that is Σ31 or more has a TiCN layer that accounts for 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) that is Σ3 or more. The lower layer can be formed as follows, for example.
That is, first, a Ti compound layer composed of one or more of TiC layer, TiN layer, TiCN layer, TiCO layer, and TiCNO layer is hard-coated on the tool base surface using a normal chemical vapor deposition apparatus. Vapor deposition is performed as a lower layer of the layer (note that it is of course possible to deposit only the TiCN layer).
For at least one TiCN layer of the lower layers,
Reaction gas composition (volume%): TiCl 4 1-3%, CH 3 CN 0.3-1.0%, N 2 25-60%, HCl 0.05% -0.2%, Ar 3-15% , Balance H 2 ,
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 5 to 10 kPa,
By performing chemical vapor deposition under the conditions, a TiCN layer having the predetermined constituent atom shared lattice point form (unit form) can be formed.
　また、上記で蒸着形成したΣ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％以上を占めるＴｉＣＮ層において、Σ３の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の２０％以下であり、さらに、Σ５の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の３０％以下であるＴｉＣＮ層は、化学蒸着をより限定した条件で行うことによって形成することができる。
例えば、以下のような条件である。
　反応ガス組成（容量％）：ＴｉＣｌ４　２～３％、ＣＨ３ＣＮ　０．５～０．８％、Ｎ２　　　２５～４５％、ＨＣｌ　０．０８％～０．１５％、Ａｒ　５～１０％、残部Ｈ２、
　反応雰囲気温度：８２０～９００℃、
　反応雰囲気圧力：５～７ｋＰａ、
上記の条件で化学蒸着することにより、Σ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％以上を占め、また、Σ３の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の２０％以下であり、さらに、Σ５の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の３０％以下であるＴｉＣＮ層を形成することができる。 Further, the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ31 or more formed by vapor deposition is 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ3 or more. In the occupied TiCN layer, the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 is 20% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 to Σ29, The TiCN layer in which the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ5 is 30% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 to Σ29 It can be formed by performing under limited conditions.
For example, the conditions are as follows.
Reaction gas composition (volume%): TiCl 4 2-3%, CH 3 CN 0.5-0.8%, N 2 25-45%, HCl 0.08% -0.15%, Ar 5-10% , Balance H 2 ,
Reaction atmosphere temperature: 820 to 900 ° C.
Reaction atmosphere pressure: 5 to 7 kPa,
By chemical vapor deposition under the above conditions, the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ31 or more is 80 of the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ3 or more. And the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 is 20% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 to Σ29, Furthermore, a TiCN layer in which the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ5 is 30% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 to Σ29 is formed. Can do.
下部層のうちの少なくとも１層のＴｉＣＮ層の結晶粒のアスペクト比：
　前記化学蒸着法により形成した特定の構成原子共有格子点形態（単位形態）を有する下部層のＴｉＣＮ層は、柱状縦長組織を有している。
例えば、前記ＴｉＣＮ層のＴｉＣＮ結晶粒の最大粒子幅Ｗと層厚方向の最大粒子長さＬから求められるアスペクト比が３以上である柱状縦長成長ＴｉＣＮ結晶粒の占める面積割合が、ＴｉＣＮ層の縦断面面積の８０面積％以上となり、柱状縦長組織の特徴であるすぐれた耐摩耗性向上効果を期待することができる。
なお、前記最大粒子幅Ｗ、最大粒子長さＬとは、柱状縦長成長ＴｉＣＮ結晶粒について、ＴｉＣＮ層の縦断面における１つの結晶粒を計測したとき、層厚方向に対して垂直な方向の結晶粒の幅（短辺）で最も大きい値を最大粒子幅Ｗと呼び、一方、層厚方向の結晶粒の高さ（長辺）で最も大きい値を最大粒子長さＬと呼ぶ。
ＴｉＣＮ層の縦断面において最大粒子幅Ｗの分布を算出し、その分布で最大ピークを示す値については０．３～１．０μｍであることが望ましく、Ｗの分布の最大ピーク値が０．３未満のＴｉＣＮ結晶粒は柱状縦長組織の特徴であるすぐれた耐摩耗性向上効果を期待できず、Ｗの分布の最大ピーク値が１．０より大きい場合は、ＴｉＣＮ結晶粒が粗粒となり、硬質被覆層のチッピングを引き起こしやすくなる。 Aspect ratio of crystal grains of at least one TiCN layer of the lower layer:
The lower TiCN layer having a specific constituent atomic shared lattice point form (unit form) formed by the chemical vapor deposition method has a columnar vertically elongated structure.
For example, the area ratio occupied by columnar vertically grown TiCN crystal grains having an aspect ratio of 3 or more determined from the maximum grain width W of the TiCN crystal grains of the TiCN layer and the maximum grain length L in the layer thickness direction is the longitudinal section of the TiCN layer. It is 80% by area or more of the surface area, and an excellent effect of improving wear resistance, which is a feature of the columnar vertically long structure, can be expected.
The maximum particle width W and the maximum particle length L are the crystal in the direction perpendicular to the layer thickness direction when one crystal grain in the longitudinal section of the TiCN layer is measured for the columnar vertically grown TiCN crystal grains. The largest value of the grain width (short side) is called the maximum grain width W, while the largest value of the crystal grain height (long side) in the layer thickness direction is called the maximum grain length L.
The distribution of the maximum particle width W is calculated in the longitudinal section of the TiCN layer, and the value indicating the maximum peak in the distribution is preferably 0.3 to 1.0 μm, and the maximum peak value of the W distribution is 0.3 TiCN crystal grains less than that cannot be expected to have an excellent effect of improving wear resistance, which is a feature of columnar vertically long structure. When the maximum peak value of W distribution is larger than 1.0, TiCN crystal grains become coarse and hard. It tends to cause chipping of the coating layer.
上部層：
　前記で形成した下部層の表面に、従来から知られている化学蒸着法によって上部層のα－Ａｌ２Ｏ３層を形成するが、上部層の平均層厚が、１μｍ未満であると長期の使用に亘ってすぐれた耐摩耗性を発揮することができず、一方、１５μｍを越えると、チッピングが発生し易くなることから、上部層の層厚は１～１５μｍと定めた。 Upper layer:
An upper α-Al 2 O 3 layer is formed on the surface of the lower layer formed in the above by a conventionally known chemical vapor deposition method. If the average thickness of the upper layer is less than 1 μm, a long-term Excellent wear resistance cannot be exhibited over use. On the other hand, if the thickness exceeds 15 μm, chipping tends to occur. Therefore, the thickness of the upper layer is determined to be 1 to 15 μm.
　本発明によれば、硬質被覆層が、工具基体の表面に形成された下部層と該下部層上に形成された上部層とを有し、下部層は、ＴｉＣ、ＴｉＮ、ＴｉＣＮ、ＴｉＣＯ、ＴｉＣＮＯのうちの２層以上のＴｉ化合物層からなり、かつ、その内の少なくとも１層はＴｉＣＮ層であって、該ＴｉＣＮ層は、全対応粒界長に占める各構成原子共有格子点からなる対応粒界長の割合が示された対応粒界分布グラフにおいて、Σ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％を占め、あるいは、さらに、Σ３の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の２０％以下であり、また、Σ５の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の３０％以下であることによって、該ＴｉＣＮ層には靱性の高い粒界が多く分布する。
このため、本発明被覆工具は、鋼、ステンレス鋼等の切削加工を、切刃に断続的・衝撃的な高負荷が作用する高速高切り込み断続条件あるいは高速高送り断続条件で行った場合でも、硬質被覆層のチッピング発生、剥離発生が抑制され、長期の使用にわたってすぐれた切削性能を発揮する。 According to the present invention, the hard coating layer has a lower layer formed on the surface of the tool base and an upper layer formed on the lower layer, and the lower layer is TiC, TiN, TiCN, TiCO, TiCNO. And at least one of them is a TiCN layer, and the TiCN layer is a corresponding grain composed of each constituent atom shared lattice point in the total corresponding grain boundary length. In the corresponding grain boundary distribution graph in which the ratio of the boundary lengths is shown, the grain boundary length of the constituent atom shared lattice point form (unit form) that is Σ31 or more is of the constituent atom shared lattice point form (unit form) that is Σ3 or more. It accounts for 80% of the grain boundary length, or the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 is equal to the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 to Σ29. 20% or less, and Σ5 constituent atom sharing The grain boundary length in the sub-point form (unit form) is 30% or less of the grain boundary length in the constituent atomic shared lattice point form (unit form) of Σ3 to Σ29, so that the TiCN layer has a high toughness grain boundary. Many are distributed.
For this reason, the coated tool of the present invention, even when cutting of steel, stainless steel, etc., is performed under high-speed high-cutting intermittent conditions or high-speed high-feed intermittent conditions where intermittent and impactful high loads act on the cutting blade, Occurrence of chipping and peeling of the hard coating layer is suppressed, and excellent cutting performance is exhibited over a long period of use.
本発明被覆工具の下部層のＴｉＣＮ層の全対応粒界長に占める各構成原子共有格子点形態（単位形態）の粒界長の割合が示された構成原子共有格子点分布グラフの一つの例を示す。One example of a constituent atomic shared lattice distribution graph showing the ratio of the grain boundary length of each constituent atomic shared lattice point form (unit form) to the total corresponding grain boundary length of the TiCN layer of the lower layer of the coated tool of the present invention Indicates. 図１に示す本発明被覆工具の下部層のＴｉＣＮ層のΣ３～Σ２９の対応粒界長に占める各構成原子共有格子点形態（単位形態）の粒界長の割合が示された構成原子共有格子点分布グラフを示す。Constituent atomic shared lattice showing the ratio of the grain boundary length of each constituent atomic shared lattice point form (unit form) to the corresponding grain boundary length of Σ3 to Σ29 of the TiCN layer of the lower layer of the coated tool shown in FIG. A point distribution graph is shown. 本発明被覆工具の下部層のＴｉＣＮ層の全対応粒界長に占める各構成原子共有格子点形態（単位形態）の粒界長の割合が示された構成原子共有格子点分布グラフの他の例を示す。Another example of the constituent atom shared lattice point distribution graph showing the ratio of the grain boundary length of each constituent atom shared lattice point form (unit form) to the total corresponding grain boundary length of the TiCN layer of the lower layer of the coated tool of the present invention Indicates. 図３示す本発明被覆工具の下部層のＴｉＣＮ層のΣ３～Σ２９の対応粒界長に占める各構成原子共有格子点形態（単位形態）の粒界長の割合が示された構成原子共有格子点分布グラフを示す。Constituent atomic shared lattice points showing the ratio of the grain boundary length of each constituent atomic shared lattice point form (unit form) to the corresponding grain boundary length of Σ3 to Σ29 of the TiCN layer of the lower layer of the coated tool of the present invention shown in FIG. A distribution graph is shown. 比較被覆工具の下部層のＴｉＣＮ層の全対応粒界長に占める各構成原子共有格子点形態（単位形態）の粒界長の割合が示された構成原子共有格子点分布グラフの一つの例を示す。An example of a constituent atomic shared lattice distribution graph showing the ratio of the grain boundary length of each constituent atomic shared lattice point form (unit form) to the total corresponding grain boundary length of the TiCN layer of the lower layer of the comparative coated tool Show.
　本発明の被覆工具について、実施例に基づいて具体的に説明する。 The coated tool of the present invention will be specifically described based on examples.
　原料粉末として、いずれも１～３μｍの平均粒径を有するＷＣ粉末、ＴｉＣ粉末、ＺｒＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｃｒ３Ｃ２粉末、ＴｉＮ粉末、およびＣｏ粉末を用意し、これら原料粉末を、表１に示される配合組成に配合し、さらにワックスを加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、９８ＭＰａの圧力で所定形状の圧粉体にプレス成形し、この圧粉体を５Ｐａの真空中、１３７０～１４７０℃の範囲内の所定の温度に１時間保持の条件で真空焼結し、焼結後、ＩＳＯ規格ＣＮＭＧ１２０４０８のインサート形状をもったＷＣ基超硬合金製の工具基体Ａ～Ｄをそれぞれ製造した。 As raw material powders, WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr 3 C 2 powder, TiN powder, and Co powder each having an average particle diameter of 1 to 3 μm are prepared. Then, blended into the composition shown in Table 1, added with wax, ball mill mixed in acetone for 24 hours, dried under reduced pressure, and then press-molded into a green compact of a predetermined shape at a pressure of 98 MPa. WC-based cemented carbide tool having an ISO standard CNMG120408 insert shape after being sintered in a vacuum of 5 Pa at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour. Substrates A to D were produced respectively.
　また、原料粉末として、いずれも０．５～２μｍの平均粒径を有するＴｉＣＮ（質量比でＴｉＣ／ＴｉＮ＝５０／５０）粉末、ＺｒＣ粉末、ＴａＣ粉末、Ｍｏ2Ｃ粉末、ＷＣ粉末、Ｃｏ粉末およびＮｉ粉末を用意し、これら原料粉末を、表２に示される配合組成に配合し、ボールミルで２４時間湿式混合し、乾燥した後、９８ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を１．３ｋＰａの窒素雰囲気中、温度：１５００℃に１時間保持の条件で焼結し、焼結後、ＩＳＯ規格ＣＮＭＧ１２０４１２のインサート形状をもったＴｉＣＮ基サーメット製の工具基体Ｅを作製した。 In addition, as raw material powders, TiCN (TiC / TiN = 50/50 by mass ratio) powder, ZrC powder, TaC powder, Mo 2 C powder, WC powder, Co powder all having an average particle diameter of 0.5 to 2 μm And Ni powder are prepared, these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and then pressed into a compact at a pressure of 98 MPa. The body was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, a tool base E made of TiCN-based cermet having an insert shape of ISO standard CNMG120212 was produced.
　ついで、これらの工具基体Ａ～Ｄおよび工具基体Ｅのそれぞれを、通常の化学蒸着装置に装入し、以下の工程で硬質被覆層を形成した。
（ａ）まず、表３に示される条件にて、表６に示される目標層厚の下部層としてのＴｉ化合物層を蒸着形成した。
（ｂ）ただし、上記下部層のうち、少なくとも１層のＴｉＣＮ層の形成に際しては、表４に示される条件Ａ～ＤにてＴｉＣＮ層を蒸着形成した。
（ｃ）次に、表３に示される条件にて、表８に示される目標層厚の上部層としてのα－Ａｌ２Ｏ３層を蒸着形成した。
上記の（ａ）～（ｃ）の工程で、表６、表８に示される硬質被覆層を有する本発明被覆工具１～１３をそれぞれ製造した。 Next, each of the tool bases A to D and the tool base E was charged into a normal chemical vapor deposition apparatus, and a hard coating layer was formed by the following steps.
(A) First, under the conditions shown in Table 3, a Ti compound layer as a lower layer having a target layer thickness shown in Table 6 was formed by vapor deposition.
(B) However, when forming at least one TiCN layer among the lower layers, a TiCN layer was formed by vapor deposition under the conditions A to D shown in Table 4.
(C) Next, an α-Al 2 O 3 layer as an upper layer having the target layer thickness shown in Table 8 was formed by vapor deposition under the conditions shown in Table 3.
In the above steps (a) to (c), the inventive coated tools 1 to 13 having the hard coating layer shown in Tables 6 and 8 were produced, respectively.
　また、比較の目的で、前記本発明被覆工具１～１３の製造条件から外れる条件で硬質被覆層を蒸着することにより、表７、表９に示す硬質被覆層を有する比較例被覆工具１～１３をそれぞれ製造した。
　具体的には、前記本発明被覆工具１～１３の製造工程（ａ）、（ｂ）における下部層の形成にあたり、下部層のうちのＴｉＣＮ層の形成に際して、表５に示される条件ａ～ｄにて、表７に示されるＴｉＣＮ層を蒸着形成した。 For comparison purposes, comparative coating tools 1 to 13 having the hard coating layers shown in Tables 7 and 9 are deposited by vapor-depositing the hard coating layers under conditions that deviate from the manufacturing conditions of the inventive coated tools 1 to 13. Were manufactured respectively.
Specifically, in forming the lower layer in the manufacturing steps (a) and (b) of the coated tools 1 to 13 according to the present invention, the conditions a to d shown in Table 5 are required for forming the TiCN layer of the lower layer. Then, a TiCN layer shown in Table 7 was formed by vapor deposition.
　ついで、本発明被覆工具１～１３と比較例被覆工具１～１３については、下部層のうちの少なくとも１層のＴｉＣＮ層について、電界放出型走査電子顕微鏡を用いて、構成原子共有格子点分布グラフをそれぞれ作成した。
　即ち、上記構成原子共有格子点分布グラフは、下部層のＴｉＣＮ層の縦断面を研磨面とした状態で、電界放出型走査電子顕微鏡の鏡筒内にセットし、前記研磨面に７０度の入射角度で１５ｋＶの加速電圧の電子線を１ｎＡの照射電流で、前記縦断面研磨面の測定範囲内に存在する結晶粒個々に照射して、電子後方散乱回折像装置を用い、３０×５０μｍの領域を０．１μｍ／ｓｔｅｐの間隔で、工具基体表面の法線に対して、前記結晶粒の結晶面である（００１）面および（０１１）面の法線がなす傾斜角を測定し、この結果得られた測定傾斜角に基づいて、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出し、前記構成原子共有格子点間に構成原子を共有しない格子点がＮ個（ＮはＮａＣｌ型面心立方晶の結晶構造上２以上の偶数となる）存在する構成原子共有格子点形態（単位形態）をΣＮ＋１で現した場合、個々のΣＮ＋１がΣＮ＋１全体（ただし、頻度の関係で上限値をＮ＝２８とする）に占める粒界長の割合を求めることにより作成した。
　なお、Σ３１以上の構成原子共有格子点形態（単位形態）の粒界長については、測定により得られたΣ３以上の全粒界長からΣ３～Σ２９までの粒界長の合計を差し引いた値を、Σ３１以上の粒界長の合計として求めた。 Next, with regard to the coated tools 1 to 13 of the present invention and the coated tools 1 to 13 of the comparative examples, at least one TiCN layer of the lower layers is formed by using a field emission scanning electron microscope and a constituent atomic shared lattice distribution graph. Was created respectively.
That is, the above constituent atomic shared lattice point distribution graph is set in a lens barrel of a field emission scanning electron microscope with the longitudinal section of the lower TiCN layer as a polished surface, and incident at 70 degrees on the polished surface. An electron beam with an accelerating voltage of 15 kV at an angle is irradiated at an irradiation current of 1 nA to individual crystal grains existing in the measurement range of the vertical cross-section polished surface, and an electron backscatter diffraction image apparatus is used to divide the region of 30 × 50 μm. At an interval of 0.1 μm / step, the inclination angle formed by the normal lines of the (001) plane and (011) plane, which are crystal planes of the crystal grains, is measured with respect to the normal line of the tool base surface. Distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains based on the obtained measurement inclination angle. Between the constituent atomic shared lattice points When constitutive atomic shared lattice point form (unit form) is expressed as ΣN + 1, where there are N lattice points that do not share the constituent atoms (N is an even number of 2 or more in the crystal structure of the NaCl type face centered cubic crystal) ΣN + 1 was determined by determining the ratio of the grain boundary length in the entire ΣN + 1 (however, the upper limit value is N = 28 in relation to the frequency).
For the grain boundary length of the constituent atomic shared lattice point form (unit form) of Σ31 or more, a value obtained by subtracting the total grain boundary length from Σ3 to Σ29 from the total grain boundary length of Σ3 or more obtained by measurement. The total of grain boundary lengths of Σ31 or more was obtained.
　この結果得られた、下部層のＴｉＣＮ層においてΣ３１以上の構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長に占める割合、また、Σ３の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長に占める割合、さらに、Σ５の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長に占める割合を、表８、表９に示した。 As a result, the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ31 or more in the lower TiCN layer becomes the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 or more. Occupancy ratio, grain boundary length of constituent atom shared lattice point form (unit form) of Σ3, proportion of grain boundary length of constituent atom shared lattice point form (unit form) of Σ3 to Σ29, and composition of Σ5 Tables 8 and 9 show the ratio of the grain boundary length of the atomic shared lattice point form (unit form) to the grain boundary length of the constituent atomic shared lattice point form (unit form) of Σ3 to Σ29.
　図１には、Σ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％以上を占める本発明被覆工具１のＴｉＣＮ層の構成原子共有格子点分布グラフの例を示す。
　図２には、前記本発明被覆工具１のＴｉＣＮ層のΣ３～Σ２９の対応粒界長に占める各構成原子共有格子点形態（単位形態）の粒界長の割合が示された構成原子共有格子点分布グラフを示すが、図２においては、Σ３～Σ２９の対応粒界長に占めるΣ３の割合は２６％、Σ５の割合は１８％であることがわかる。
　図３には、Σ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％以上を占める本発明被覆工具２のＴｉＣＮ層の構成原子共有格子点分布グラフの例を示すが、図４に示されるように、本発明被覆工具２のΣ３の構成原子共有格子点形態（単位形態）の粒界長は、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の２０％以下であり、かつ、Σ５の構成原子共有格子点形態（単位形態）の粒界長は、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の３０％以下であることがわかる。 FIG. 1 shows that the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ31 or more occupies 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ3 or more. The example of the constituent atom shared lattice point distribution graph of the TiCN layer of the invention coated tool 1 is shown.
FIG. 2 shows a constituent atomic shared lattice in which the proportion of the grain boundary length of each constituent atomic shared lattice point form (unit form) in the corresponding grain boundary length of Σ3 to Σ29 of the TiCN layer of the coated tool 1 of the present invention is shown. A point distribution graph is shown. In FIG. 2, it can be seen that the proportion of Σ3 in the corresponding grain boundary lengths of Σ3 to Σ29 is 26% and the proportion of Σ5 is 18%.
FIG. 3 shows that the grain boundary length of the constituent atom shared lattice point form (unit form) that is Σ31 or more occupies 80% or more of the grain boundary length of the constituent atom shared lattice point form (unit form) that is Σ3 or more. An example of the constituent atomic shared lattice point distribution graph of the TiCN layer of the invention-coated tool 2 is shown. As shown in FIG. 4, the grain boundary of the constituent atomic shared lattice point form (unit form) of Σ3 of the inventive coated tool 2 The length is 20% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 to Σ29, and the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ5 is Σ3 to It can be seen that it is 30% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ29.
　表８に示されるとおり、本発明被覆工具の下部層のＴｉＣＮ層は、いずれもΣ３１以上の構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上の構成原子共有格子点形態（単位形態）の粒界長の８０％以上であり、また、いくつかについては、Σ３の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の２０％以下であり、かつ、Σ５の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の３０％以下であった。
　これに対して、表９に示されるとおり、比較例被覆工具のＴｉＣＮ層については、いずれも、Σ３１以上の構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上の構成原子共有格子点形態（単位形態）の粒界長の８０％未満であった。
　なお、図５に、比較例被覆工具１のＴｉＣＮ層の全対応粒界長に占める各構成原子共有格子点形態（単位形態）の粒界長の割合が示された構成原子共有格子点分布グラフの一つの例を示すが、Σ３１以上の構成原子共有格子点形態（単位形態）の粒界長は、Σ３以上の構成原子共有格子点形態（単位形態）の粒界長の６０％であった。 As shown in Table 8, the TiCN layer of the lower layer of the coated tool of the present invention has a constituent atom shared lattice point form in which the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ31 or more is Σ3 or more ( 80% or more of the grain boundary length of the unit form), and in some cases, the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 is the constituent atom shared lattice point form of Σ3 to Σ29 ( Grains having a grain boundary length of Σ3 to Σ29 that are 20% or less of the grain boundary length of (unit form) and the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ5 It was 30% or less of the field length.
On the other hand, as shown in Table 9, all of the TiCN layers of the comparative coated tools have constituent atom sharing in which the grain boundary length of the constituent atom sharing lattice point form (unit form) of Σ31 or more is Σ3 or more. It was less than 80% of the grain boundary length in the lattice point form (unit form).
In addition, the constituent atom shared lattice point distribution graph in which the ratio of the grain boundary length of each constituent atom shared lattice point form (unit form) to the total corresponding grain boundary length of the TiCN layer of the comparative coated tool 1 is shown in FIG. In this example, the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ31 or more was 60% of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 or more. .
　また、本発明被覆工具１～１３、比較例被覆工具１～１３の硬質被覆層の各構成層の厚さを、走査型電子顕微鏡を用いて縦断面測定したところ、いずれも目標層厚と実質的に同じ平均層厚（５点測定の平均値）を示した。
　表６～表９に、その結果を示す。 Further, the thicknesses of the constituent layers of the hard coating layers of the coated tools 1 to 13 of the present invention and the comparative coated tools 1 to 13 were measured longitudinally using a scanning electron microscope. The same average layer thickness (average value of 5-point measurement) was shown.
Tables 6 to 9 show the results.
　さらに、本発明被覆工具１～１３、比較被覆工具１～１３の下部層のＴｉＣＮ層の縦断面について、走査型電子顕微鏡（倍率５０００倍）を用いて、工具基体表面と平行な方向に１０μｍ、工具基体と垂直な方向にＴｉＣＮ層の層厚分の高さの領域内に存在するＴｉＣＮ結晶粒のそれぞれについて最大粒子幅Ｗ、最大粒子長さＬを測定し、分布を算出し、最大粒子幅Ｗの分布の最大ピークを示す値を算出した。ＴｉＣＮ結晶粒のそれぞれについてアスペクト比Ｌ／Ｗの値を求め、アスペクト比Ｌ／Ｗが３以上である結晶粒が、ＴｉＣＮ層の縦断面に占める面積割合を求めた。
　表８、表９に、その結果を示す。 Further, with respect to the longitudinal section of the TiCN layer as the lower layer of the coated tools 1 to 13 of the present invention and the comparative coated tools 1 to 13, using a scanning electron microscope (5000 times magnification), 10 μm in the direction parallel to the tool substrate surface, The maximum particle width W and the maximum particle length L are measured for each TiCN crystal grain existing in the region of the height of the TiCN layer in the direction perpendicular to the tool substrate, the distribution is calculated, and the maximum particle width is calculated. A value indicating the maximum peak of the W distribution was calculated. The value of the aspect ratio L / W was determined for each of the TiCN crystal grains, and the area ratio of the crystal grains having an aspect ratio L / W of 3 or more in the longitudinal section of the TiCN layer was determined.
Tables 8 and 9 show the results.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
　つぎに、本発明被覆工具１～１３、比較例被覆工具１～１３の各種の被覆工具について、いずれも工具鋼製バイトの先端部に固定治具にてネジ止めした状態で、
　被削材：ＪＩＳ・ＳＵＳ６３０の長さ方向等間隔４本縦溝入り、
　切削速度：３００ｍ／ｍｉｎ、
　切り込み：３．０ｍｍ、
　送り：０．３ｍｍ／ｒｅｖ、
　切削時間：５分、
の条件（切削条件Ａという）で、ステンレス鋼の湿式高速断続高切り込み切削試験（通常の切削速度、切り込みは、それぞれ、７０ｍ／ｍｉｎ、２．０ｍｍ）、
　被削材：ＪＩＳ・Ｓ６０Ｃの長さ方向等間隔４本縦溝入り、
　切削速度：３００ｍ／ｍｉｎ、
　切り込み：１．５ｍｍ、
　送り：１．０ｍｍ／ｒｅｖ、
　切削時間：５分、
の条件（切削条件Ｂという）で、高炭素鋼の湿式高速断続高送り切削試験（通常の切削速度、送り量は、それぞれ、１００ｍ／ｍｉｎ、０．３ｍｍ／ｒｅｖ）、
を行い、いずれの切削試験でも切刃の逃げ面摩耗幅を測定した。
　表１０にこの測定結果を示した。 Next, for the various coated tools of the present coated tools 1 to 13 and the comparative coated tools 1 to 13, all of them were screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SUS630 in the longitudinal direction with four equally spaced grooves,
Cutting speed: 300 m / min,
Cutting depth: 3.0 mm,
Feed: 0.3mm / rev,
Cutting time: 5 minutes
In a condition (referred to as cutting condition A), a wet high-speed intermittent high-cut cutting test of stainless steel (normal cutting speed and cutting are 70 m / min and 2.0 mm, respectively),
Work material: JIS / S60C lengthwise equidistant 4 grooves,
Cutting speed: 300 m / min,
Incision: 1.5mm,
Feed: 1.0mm / rev,
Cutting time: 5 minutes
In a condition (referred to as cutting condition B), a wet high-speed intermittent high-feed cutting test of high-carbon steel (normal cutting speed and feed amount are 100 m / min and 0.3 mm / rev, respectively)
In each cutting test, the flank wear width of the cutting edge was measured.
Table 10 shows the measurement results.
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
　表１０に示される結果から、本発明被覆工具１～１３は、その下部層のＴｉＣＮ層が、すぐれた靱性を備えるため、耐チッピング性にすぐれ、長期の使用に亘ってすぐれた切削性能を示した。
　これに対して、比較例被覆工具１～１３は、高速断続重切削加工では、硬質被覆層のチッピング発生、剥離発生等により、比較的短時間で使用寿命に至ることが明らかである。 From the results shown in Table 10, the coated tools 1 to 13 of the present invention have excellent chipping resistance because the TiCN layer of the lower layer has excellent toughness, and excellent cutting performance over a long period of use. It was.
On the other hand, it is apparent that the comparative coated tools 1 to 13 reach the service life in a relatively short time due to the occurrence of chipping and peeling of the hard coating layer in high-speed intermittent heavy cutting.
　前述のように、本発明の被覆工具は、切れ刃に高負荷が作用する炭素鋼やステンレス鋼などの高速高切り込み・高送りの重切削という厳しい切削条件下でも、硬質被覆層のチッピング、剥離が発生することはなく、長期の使用に亘ってすぐれた切削性能を発揮するものであるから、切削装置の高性能化並びに切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。 As described above, the coated tool of the present invention is capable of chipping and peeling the hard coating layer even under severe cutting conditions such as high-speed, high-cutting and high-feed heavy cutting such as carbon steel and stainless steel in which a high load acts on the cutting edge. Since it exhibits excellent cutting performance over a long period of use, it is fully satisfactory for higher performance of cutting equipment, labor saving and energy saving of cutting, and cost reduction. It can be done.

Claims (2)

  1. 　炭化タングステン基超硬合金または炭窒化チタン基サーメットで構成された工具基体の表面に下部層と上部層からなる硬質被覆層が設けられている表面被覆切削工具において、
    （ａ）前記下部層は、３～２０μｍの合計平均層厚を有し、ＴｉＣ、ＴｉＮ、ＴｉＣＮ、ＴｉＣＯ、ＴｉＣＮＯのうちの1層または２層以上からなるＴｉ化合物層であって、その内の少なくとも１層はＴｉＣＮ層で構成されており、
    （ｂ）前記上部層は、１～１５μｍの平均層厚を有し、α型の結晶構造を有するＡｌ２Ｏ３層からなり、
    （ｃ）前記下部層の少なくとも１層のＴｉＣＮ層について、電界放出型走査電子顕微鏡を用い、前記少なくとも１層のＴｉＣＮ層の縦断面の測定範囲内に存在する結晶粒個々に電子線を照射し、電子後方散乱回折像装置を用いて、所定領域を０．１μｍ／ｓｔｅｐの間隔で、基体表面の法線に対する、前記結晶粒の結晶面である（００１）面および（０１１）面の法線がなす傾斜角を測定し、この場合前記結晶粒は、格子点にＴｉ、炭素、および窒素からなる構成原子がそれぞれ存在するＮａＣｌ型面心立方晶の結晶構造を有し、この結果得られた測定傾斜角に基づいて、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出すると共に、前記構成原子共有格子点間に存在する構成原子を共有しない格子点の数Ｎ毎に定めたΣＮ＋１で表される構成原子共有格子点形態（単位形態）のそれぞれの分布割合を算出した場合に、全対応粒界長に占める各構成原子共有格子点からなる対応粒界長の割合が示された対応粒界分布グラフにおいて、Σ３１以上である構成原子共有格子点形態（単位形態）の粒界長が、Σ３以上である構成原子共有格子点形態（単位形態）の粒界長の８０％以上を占め、
    （ｄ）前記少なくとも１層のＴｉＣＮ層の縦断面において、アスペクト比が３以上であるＴｉＣＮ結晶粒が８０％以上の面積割合を占めることを特徴とする表面被覆切削工具。     In a surface-coated cutting tool in which a hard coating layer composed of a lower layer and an upper layer is provided on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
    (A) The lower layer is a Ti compound layer having a total average layer thickness of 3 to 20 μm and comprising one or more of TiC, TiN, TiCN, TiCO, and TiCNO, At least one layer is composed of a TiCN layer,
    (B) the upper layer comprises an Al 2 O 3 layer having an average layer thickness of 1 to 15 μm and having an α-type crystal structure;
    (C) At least one TiCN layer of the lower layer is irradiated with an electron beam on each crystal grain existing within the measurement range of the longitudinal section of the at least one TiCN layer using a field emission scanning electron microscope. Then, using an electron backscatter diffraction image apparatus, the normal areas of the (001) plane and (011) plane, which are crystal planes of the crystal grains, with respect to the normal line of the substrate surface with respect to the normal line of the predetermined region at an interval of 0.1 μm / step In this case, the crystal grains have a NaCl type face-centered cubic crystal structure in which constituent atoms composed of Ti, carbon, and nitrogen are present at lattice points, respectively. Based on the measured tilt angle, the distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains is calculated. Together with the above When the distribution ratio of each constituent atom shared lattice point form (unit form) represented by ΣN + 1 determined for each number N of lattice points that do not share constituent atoms existing between the shared atomic lattice points is calculated, In the corresponding grain boundary distribution graph in which the proportion of the corresponding grain boundary length composed of each constituent atom shared lattice point in the corresponding grain boundary length is shown, the grain boundary length of the constituent atom shared lattice point form (unit form) which is Σ31 or more is Occupy 80% or more of the grain boundary length of the constituent atomic shared lattice point form (unit form) that is Σ3 or more,
    (D) A surface-coated cutting tool characterized in that, in the longitudinal section of the at least one TiCN layer, TiCN crystal grains having an aspect ratio of 3 or more occupy an area ratio of 80% or more.
  2. 　前記下部層の少なくとも１層のＴｉＣＮ層について、電界放出型走査電子顕微鏡を用い、前記少なくとも１層のＴｉＣＮ層の縦断面の測定範囲内に存在する結晶粒個々に電子線を照射し、電子後方散乱回折像装置を用いて、所定領域を０．１μｍ／ｓｔｅｐの間隔で、基体表面の法線に対する、前記結晶粒の結晶面である（００１）面および（０１１）面の法線がなす傾斜角を測定し、この場合前記結晶粒は、格子点にＴｉ、炭素、および窒素からなる構成原子がそれぞれ存在するＮａＣｌ型面心立方晶の結晶構造を有し、この結果得られた測定傾斜角に基づいて、相互に隣接する結晶粒の界面で、前記構成原子のそれぞれが前記結晶粒相互間で１つの構成原子を共有する格子点（構成原子共有格子点）の分布を算出すると共に、前記構成原子共有格子点間に存在する構成原子を共有しない格子点の数Ｎ毎に定めたΣＮ＋１で表される構成原子共有格子点形態（単位形態）のそれぞれの分布割合を算出した場合に、Σ３の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の２０％以下であり、また、Σ５の構成原子共有格子点形態（単位形態）の粒界長が、Σ３～Σ２９の構成原子共有格子点形態（単位形態）の粒界長の３０％以下であることを特徴とする請求項１に記載の表面被覆切削工具。 For the at least one TiCN layer of the lower layer, using a field emission scanning electron microscope, each crystal grain existing within the measurement range of the longitudinal section of the at least one TiCN layer is irradiated with an electron beam, Using a scattering diffraction image apparatus, the inclination of the normal lines of the (001) plane and the (011) plane, which are crystal planes of the crystal grains, with respect to the normal line of the substrate surface at a predetermined area of 0.1 μm / step In this case, the crystal grains have a NaCl-type face-centered cubic crystal structure in which constituent atoms composed of Ti, carbon, and nitrogen are present at lattice points. And calculating the distribution of lattice points (constituent atom shared lattice points) in which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains, and Constitution When each distribution ratio of the constituent atom shared lattice point form (unit form) represented by ΣN + 1 determined for each number N of lattice points that do not share the constituent atoms existing between the child shared lattice points is calculated, The grain boundary length of the constituent atomic shared lattice point form (unit form) is 20% or less of the grain boundary length of the constituent atomic shared lattice point form (unit form) of Σ3 to Σ29, and the constituent atomic shared lattice point of Σ5 The surface-coated cutting tool according to claim 1, wherein the grain boundary length of the form (unit form) is 30% or less of the grain boundary length of the constituent atom shared lattice point form (unit form) of Σ3 to Σ29. .
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Citations (5)

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JP2007260851A (en) * 2006-03-29 2007-10-11 Kyocera Corp Surface coated cutting tool
JP2009035802A (en) * 2007-08-03 2009-02-19 Sumitomo Electric Ind Ltd Cemented carbide
JP2013166226A (en) * 2012-02-16 2013-08-29 Mitsubishi Materials Corp Surface coated cutting tool that demonstrates chipping resistance with excellent hard coating layer
JP2015231662A (en) * 2014-05-16 2015-12-24 三菱マテリアル株式会社 Surface-coated cutting tool
EP3000913A1 (en) * 2014-09-26 2016-03-30 Walter Ag Coated cutting tool insert with MT-CVD TiCN on TiAI(C,N)

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007260851A (en) * 2006-03-29 2007-10-11 Kyocera Corp Surface coated cutting tool
JP2009035802A (en) * 2007-08-03 2009-02-19 Sumitomo Electric Ind Ltd Cemented carbide
JP2013166226A (en) * 2012-02-16 2013-08-29 Mitsubishi Materials Corp Surface coated cutting tool that demonstrates chipping resistance with excellent hard coating layer
JP2015231662A (en) * 2014-05-16 2015-12-24 三菱マテリアル株式会社 Surface-coated cutting tool
EP3000913A1 (en) * 2014-09-26 2016-03-30 Walter Ag Coated cutting tool insert with MT-CVD TiCN on TiAI(C,N)

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