JP7183519B2 - A surface cutting tool with a hard coating that exhibits excellent chipping resistance - Google Patents

Description

In the cutting of work materials that require toughness, such as alloy steel and cast iron, the present invention provides a hard coating layer that exhibits excellent resistance during high-speed interrupted cutting, in which an impact load acts on the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter sometimes referred to as "coated tool") that exhibits excellent cutting performance over long-term use by providing chipping resistance.

Conventionally, in general, tungsten carbide (hereinafter referred to as "WC") based cemented carbide, titanium carbonitride (hereinafter referred to as "TiCN") based cermet or cubic boron nitride (hereinafter referred to as "cBN") based cemented carbide A Ti—Al-based composite nitride layer is coated as a hard coating layer on the surface of a tool base made of a high-pressure sintered body (hereinafter collectively referred to as “tool base”) by a PVD method or a CVD method. There are formed coated tools, which are known to exhibit excellent wear resistance.
However, although the conventional coated tools coated with the Ti—Al-based composite nitride layer or composite carbonitride layer have relatively excellent wear resistance, they may cause abnormalities such as chipping when used under high-speed interrupted cutting conditions. Various proposals have been made to improve the hard coating layer because it is prone to wear.

For example, Patent Document 1 discloses a surface-coated cutting tool comprising a substrate and a coating film formed on the substrate, wherein the coating film comprises one or more A layers and one or more layers and two or more C layers, wherein the bottom layer in contact with the substrate is the C layer, and the A layer and the B layer have a structure in which the C layer is sandwiched and alternately laminated, The A layer has a chemical formula of Al _a Ti _b M _c (wherein a, b, and c each represent an atomic ratio, 0.4<a<0.75, 0≦b<0.6, 0<c<0 .3, a + b + c = 1, and M represents at least one element selected from the group consisting of Si, Cr, V, Y, Zr, B, Nb, Mo and Mn.) The B layer has a chemical formula of Ti _{d Sie} (where d and e each represent an atomic ratio, and 0<e<0. 3, satisfies d+e=1), and the C layer is composed of TiN.

Further, for example, in Patent Document 2, (Ti _a , Al _b , M _c ) (C _1-d N _d ) is a hard film consisting of
0.02 ≤ a ≤ 0.2, 0.8 ≤ b ≤ 0.95, a + b + c = 1, 0.5 ≤ d ≤ 1 (M is one or more metal or metalloid elements, a , b and c respectively indicate the atomic ratios of Ti, Al and M, and d indicates the atomic ratio of N. The same shall apply hereinafter). Tools are listed.

JP 2008-183671 A JP-A-2005-88130

The hard coating described in Patent Document 1 has heat resistance, toughness, and excellent adhesion between each layer of the multilayer structure. In addition to the adhesion strength of , it is inferior in hardness and strength, so peeling and chipping are likely to occur, and it cannot be said that satisfactory cutting performance is exhibited. In addition, the hard coating described in Patent Document 2 mentions that the Al content of the coating is increased by adding a metal or semi-metallic element to the AlTiCN coating, and has a predetermined hardness and oxidation resistance. Although it has poor wear resistance, it cannot be said that satisfactory cutting performance is exhibited.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a coated tool in which a hard coating layer exhibits excellent chipping resistance over a long period of time even during high-speed intermittent cutting of alloy steel, cast iron, and the like.

The present inventor has attempted to improve the chipping resistance of coated tools even when subjected to high-speed intermittent cutting of alloy steel, cast iron, etc., and has developed a composition of a hard coating layer that has excellent chipping resistance over long-term use. As a result of earnest research on and organization, the following knowledge was obtained.

That is, the present inventors have found that the hard coating layer has a columnar crystal structure (structure having columnar crystal grains) containing at least NaCl-type face-centered cubic crystal grains, or The present inventors have found a novel finding that adding a predetermined amount of Mn to a composite carbonitride layer can improve chipping resistance even during high-speed interrupted cutting of alloy steel, cast iron, and the like.
In addition, in Patent Document 1, Mn is shown as the M component contained in the A layer, and there is a description that the hardness is dramatically improved by including a specific amount of the M component. The coating layer is formed by alternately laminating an A layer that improves wear resistance and toughness and a B layer that improves heat resistance and lubricity with a C layer interposed therebetween, and does not even suggest the above findings. .

The present invention is based on the above findings,
"(1) Surface-coated cutting in which a hard coating layer is provided on the surface of a tool base made of either a tungsten carbide-based cemented carbide, a titanium carbonitride-based cermet, or a cubic boron nitride-based ultra-high pressure sintered body. in the tool,
(a) the hard coating layer includes at least a composite nitride layer or composite carbonitride layer of Ti, Al and Mn with an average layer thickness of 1.0 to 20.0 μm;
(b) The composite nitride layer or composite carbonitride layer of Ti, Al, and Mn has 70 areas of crystal grains having a NaCl-type face-centered cubic structure when analyzed from a longitudinal section perpendicular to the surface of the tool substrate. % or more, including
(c) The composite nitride layer or composite carbonitride layer of Ti, Al and Mn has a composition of
Composition formula: (Ti _1-α-β Al _α Mn _β ) (C _γ N _1-γ )
represented by the average content ratio α of Al in the total amount of Ti, Al and Mn, the average content ratio β of Mn in the total amount of Ti, Al and Mn, and the average of C in the total amount of C and N The content ratio γ (where α, β, and γ are all atomic ratios) is 0.500 ≤ α ≤ 0.900, 0.005 ≤ β ≤ 0.150, and 0.505 ≤ α + β ≤ 0.950, respectively and satisfies 0.0000 ≤ γ ≤ 0.0050,
(d) The crystal grains having the NaCl-type face-centered cubic structure of the composite nitride layer or composite carbonitride layer of Ti, Al, and Mn have a columnar crystal structure, and the area-weighted average of the crystal grains is The calculated average particle width W is 0.1 to 3.0 μm, the average aspect ratio A calculated by area weighted average is 2.0 to 10.0,
(e) When observing the longitudinal section of the composite nitride layer or composite carbonitride layer of Ti, Al, and Mn, Mn is present at the grain boundaries of the crystal grains having the NaCl-type face-centered cubic structure. And, the length of the grain boundary where Mn exists is 0.1 to 10.0% of the length of all grain boundaries of the crystal grains having the NaCl type face-centered cubic structure. Surface coated cutting tools.
( 2 ) The composite nitride layer or composite carbonitride layer of Ti, Al, and Mn contains a small amount of Cl, and the content ratio ε of Cl in the total amount of C, N, and Cl (where ε is an atom ratio) satisfies 0.0001 ≦ ε≦0.0020. ( 3 ) The composite nitride layer or composite carbonitride layer of Ti, Al, and Mn further contains Si, and its composition is
Composition formula: (Ti _1-α-β-δ Al _α Mn _β Si _δ ) (C _γ N _1-γ )
represented by the average content ratio α of Al in the total amount of Ti, Al, Mn and Si, the average content ratio β of Mn in the total amount of Ti, Al, Mn and Si, and the total amount of C and N of C When the average content ratio γ in the amount and the average content ratio δ in the total amount of Ti, Al, Mn and Si of Si (where α, β, γ, and δ are all atomic ratios), Ti in Al and Average content ratio α / (1-δ) in the total amount of Al and Mn, average content ratio β / (1-δ) in the total amount of Ti, Al and Mn in Mn, Ti and Al and Mn in Si The average content ratio δ in the total amount of Si and the average content ratio γ of C in the total amount of C and N are 0.500≦α/(1−δ)≦0.900 and 0.005≦β, respectively. / (1-δ) ≤ 0.150, 0.005 ≤ δ ≤ 0.150 and 0.505 ≤ (α + β) / (1-δ) ≤ 0.950, 0.0000 ≤ γ ≤ 0.0050 to do
The surface-coated cutting tool according to (1) or (2) , characterized by: "
is.

The tool of the present invention contains Mn in the composite nitride layer or composite carbonitride layer of Ti and Al having a columnar crystal structure, thereby improving thermal crack resistance during high-speed interrupted cutting of alloy steel, cast iron, etc. Exhibits excellent chipping resistance.

The present invention is described in detail below. In addition, when a numerical range is expressed by "-" in the present specification and claims, the range includes upper and lower numerical values.

Average layer thickness of TiAlMn(Si)CN layer:
_The hard coating layer _{of the} present invention is a _TiAlMn ( _Si ) _CN layer (Si is an optional Since Si is a component, Si is enclosed in parentheses). This TiAlMn(Si)CN layer has high hardness and excellent chipping resistance and wear resistance, and the effect is particularly noticeable when the average layer thickness is 1.0 to 20.0 μm. . This is because if the average layer thickness is less than 1.0 μm, the layer thickness is too thin to ensure sufficient wear resistance over long-term use. The crystal grains of the (Si)CN layer tend to coarsen, and chipping tends to occur.
Therefore, the average layer thickness was set to 1.0 to 20.0 μm. More preferably, it is 2.0 to 15.0 μm.
In addition, the TiAlMn(Si)CN layer referred to here does not impair the effects of the invention described above even if elements such as O element and Cl element are inevitably contained in a very small amount. It is better not to contain the O element as much as possible. Further, as will be described later, a predetermined amount of Cl element can improve the lubricity of the layer without lowering the toughness of the layer.

Area ratio of crystal grains having a NaCl-type face-centered cubic structure in the TiAlMn(Si)CN layer:
In the TiAlMn(Si)CN layer, it is preferable that crystal grains having a NaCl-type face-centered cubic crystal structure account for 70 area % or more as an area ratio. As a result, the area ratio of crystal grains having a face-centered cubic crystal structure of the NaCl type, which has high hardness, becomes relatively higher than that of crystal grains having a hexagonal crystal structure, and the effect of improving hardness can be obtained. . This area ratio is more preferably 85 area % or more.
Here, the area ratio of the NaCl-type face-centered cubic structure can be calculated by the following procedure. The area ratio of the NaCl-type crystal grains having a face-centered cubic structure was measured using a high-resolution electron beam backscatter diffraction device, and the width was 10 μm at intervals of 0.02 μm in the layer thickness direction in a longitudinal section (a section perpendicular to the tool substrate). Vertically measure within the range of layer thickness (average layer thickness), determine the number of measurement points having a NaCl-type face-centered cubic structure that constitutes the TiAlMn(Si)CN layer occupying all measurement points, and determine the area ratio. . By repeating the same measurement for five or more fields of view and calculating the average value, the area ratio (area %) occupied by the crystal grains having the NaCl-type face-centered cubic structure of the TiAlMn(Si)CN layer is obtained.

Average composition of TiAlMn(Si)CN layer:
(1) The composition of the TiAlMn(Si)CN layer containing no Si in the present invention is
Composition formula: represented by (Ti _1-α-β Al _α Mn _β ) (C _γ N _1-γ ),
The average content ratio of Al in the total amount of Ti, Al, and Mn (hereinafter referred to as “average content ratio of Al”) α is
The average content ratio of Mn in the total amount of Ti, Al, and Mn (hereinafter referred to as “average content ratio of Mn”) β is
The average content ratio of C in the total amount of C and N (hereinafter referred to as “average content ratio of C”) γ is
0.500≤α≤0.900, 0.005≤β≤0.150, 0.505≤α+β≤0.950, 0.0000≤γ≤0.0050 (where α, β, γ are Both are determined to satisfy the atomic ratio).
The reason is as follows.
When the average content ratio α of Al is less than 0.500, the TiAlMn(Si)CN layer is inferior in hardness, so that when subjected to high-speed intermittent cutting of alloy steel, cast iron, etc., the wear resistance is insufficient. On the other hand, if it exceeds 0.900, it tends to contain hexagonal crystals that are inferior in hardness, resulting in a decrease in wear resistance. Therefore, 0.500≦α≦0.900, but more preferably 0.750≦α≦0.900.
If the average content ratio β of Mn is less than 0.005, high-temperature strength cannot be ensured, and abnormal damage tends to occur. On the other hand, if it exceeds 0.150, high-temperature hardness cannot be ensured, and wear resistance decreases.
The reason why the average content ratio γ of C is set to 0.0000≦γ≦0.0050 is that the hardness can be improved while maintaining the chipping resistance within this range.

(2) The composition of the TiAlMn(Si)CN layer containing Si in the present invention is
Composition formula: represented by (Ti _1-α-β-δ Al _α Mn _β Si _δ ) (C _γ N _1-γ ),
The average content ratio of Al in the total amount of Ti, Al, and Mn (hereinafter referred to as “the average content ratio of Al corrected by the Si content”) α / (1-δ) is
The average content ratio of Mn to the total amount of Ti, Al, and Mn (hereinafter referred to as “average content ratio of Mn corrected by Si content”) β/(1−δ) is
The average content ratio of Si in the total amount of Ti, Al, Mn, and Si (hereinafter referred to as “average content ratio of Si”) δ is
The average content ratio of C in the total amount of C and N (hereinafter referred to as “average content ratio of C”) γ is
0.500≤α/(1-δ)≤0.900, 0.005≤β/(1-δ)≤0.150, 0.005≤δ≤0.150, 0.0000≤γ≤0, respectively 0.0050 (where α, β, γ, and δ are all atomic ratios).
The reason for this is that the average content ratio of Al, Mn, and C corrected by the Si content is the same as the average content ratio of Al, Mn, and C described above, and the average content ratio of Si is 0.0050. If it is less than 0.150, high-temperature strength cannot be ensured and abnormal damage tends to occur.
When 0.005≦δ≦0.150, the possible range of the average content ratio α in the total amount of Ti, Al, Mn, and Si in Al is 0.005 to the third decimal place. 425≦α≦0.896. Similarly, the possible range of the average content ratio β of Mn in the total amount of Ti, Al, Mn and Si is 0.004≦β≦0.149. In both of these two equations, the equality of the left side is established when .delta.=0.150, and the equality of the right side is established when .delta.=0.005. However, the relationship between α and β must simultaneously satisfy 0.505≤(α+β)/(1-δ)≤0.950. Also, from this formula, the range that α+β+δ should at least satisfy is 0.505×(1−δ)+δ≦α+β+δ≦0.950×(1−δ)+δ, so 0.505+0.495δ≦α+β+δ≦0.950+0. 05δ, satisfying at least 0.507<α+β+δ≦0.958. The lower limit is rounded off to the fourth decimal place. The closest value to the lower limit shown is given when .delta.=0.005, and when the equality on the right side holds, .delta.=0.150.

Content ratio of Cl:
The hard coating layer of the present invention may contain trace amounts of Cl. When forming the TiAlMn(Si)CN layer in the hard coating layer of the present invention, when HCl gas is used as a reaction gas component, or even if not used, AlCl ₃ , TiCl ₄ and SiCl ₄ are used. Si) A small amount of Cl is inevitably contained in the CN layer. 0020 is preferred. The reason is that when the amount of Cl is in this range, the lubricity can be enhanced without reducing the toughness of the layer. However, if the average chlorine content is less than 0.0001, the effect of improving lubricity is small.

Next, a method for measuring each average content ratio (α, β, δ, ε) of Al, Mn, Si and Cl will be described. Using an electron-probe-micro-analyser (EPMA), in a sample in which the surface of the TiAlMn(Si)CN layer is polished, an electron beam is irradiated from the sample surface side, and the obtained characteristic X-ray analysis. From the 10-point average of the results, the average Al content ratio α, the average Mn content ratio β, the average Si content ratio δ, and the average Cl content ratio ε are obtained.
Further, the average content ratio γ of C is obtained by secondary-ion-mass-spectrometry (SIMS). An ion beam is irradiated in a range of 70 μm × 70 μm from the sample surface side, and the concentration in the depth direction is measured for the components emitted by the sputtering action. Find the average of the directions.

Average Grain Width and Aspect Ratio of Columnar Crystal Structure in TiAlMn(Si)CN Layer:
In the present invention, the TiAlMn(Si)CN layer has a columnar crystal structure, the average grain width W in the longitudinal section of the crystal grains in the structure is 0.1 to 3.0 μm, and the average aspect ratio A is 2.0 to 10. .0 is desirable. The reason is as follows. If the average grain width W is less than 0.1 μm, fine grain crystals are prone to abnormal damage due to a decrease in resistance to plastic deformation and a decrease in oxidation resistance due to an increase in grain boundaries. On the other hand, when the average grain width W is larger than 3.0 μm, the presence of coarsely grown grains tends to lower the toughness. In addition, if the average aspect ratio A is less than 2.0, the interface between the granular crystals tends to act as a fracture starting point against the shear stress generated on the film surface during cutting, which causes chipping. In addition, when the average aspect ratio A exceeds 10.0, fine chipping occurs on the cutting edge during cutting, and when adjacent columnar crystal structures are chipped, resistance to shear stress generated on the surface of the hard coating layer is likely to become small, and breakage of the columnar crystal structure causes damage to progress at once, resulting in large chipping. Therefore, it is desirable that the average grain width W of the crystal grains is 0.1 to 3.0 μm and the average aspect ratio A is 2.0 to 10.0.

Next, a method for calculating the average grain width W and average aspect ratio A of the crystal grains, and the area ratio of the crystal grains having a NaCl-type face-centered cubic structure with a columnar crystal structure will be described. First, in the longitudinal section of the hard coating layer, grain boundaries are determined in an observation field of view of 10 μm wide in the direction parallel to the tool substrate and layer thickness (average layer thickness) in the vertical direction. First, the inside of the observation field plane is analyzed at intervals of 0.02 μm using a high-resolution electron beam backscatter diffraction apparatus to obtain measurement points having a NaCl-type face-centered cubic structure within the observation field plane. If there is an orientation difference of 5 degrees or more between adjacent measurement points (hereinafter referred to as pixels) among measurement points having this NaCl-type face-centered cubic structure, or if adjacent measurement points have an NaCl-type face-centered cubic structure If there is no measurement point, it is defined as the grain boundary. Here, the longitudinal section is a section perpendicular to the surface of the tool base. One crystal grain is defined as a region surrounded by grain boundaries and including a measurement point having a NaCl-type face-centered cubic structure. However, a single pixel that has an orientation difference of 5 degrees or more from all adjacent pixels, or that has no measurement point with an adjacent NaCl-type face-centered cubic structure, is not regarded as a crystal grain, and is two pixels or more. are connected as crystal grains. In this manner, grain boundary determination is performed to specify crystal grains. Next, image processing is performed to determine the maximum length H _i of a certain crystal grain i in the direction perpendicular to the tool substrate, the grain width W _i that is the maximum length of the crystal grain i in the horizontal direction to the substrate, and the area S of the crystal grain i. Find _i . The aspect ratio A _i of the crystal grain i is calculated as A _i =H _i /W _i . In this way, the grain widths W ₁ to W _n (n≧20) of at least 20 or more crystal grains within the observation field are averaged according to Equation 1, and the average grain width W of the crystal grains is obtained. Similarly, the aspect ratios A ₁ to A _n (n≧20) of the crystal grains are obtained, and the average aspect ratio A of the crystal grains is obtained by area-weighted averaging according to Equation 2. The average grain width W and the average aspect ratio A can be calculated based on the following formulas.

Grain boundary length ratio of grain boundaries where Mn is present:
Mn is present at the grain boundaries of the crystal grains having a NaCl-type face-centered cubic structure in the TiAlMn(Si)CN layer, and the length of the grain boundaries where Mn is present is the total grain boundary length of the crystal grains. It is preferably 0.1 to 10.0% of the total thickness. The reason for this is that the presence of an appropriate amount of Mn in the grain boundaries exerts an effect of suppressing the propagation of cracks that often propagate along the grain boundaries during cutting. If the length of the grain boundary where the Mn element exists in the total grain boundary length of the crystal grain is less than 0.1%, the above effect cannot be sufficiently obtained, and if it exceeds 10.0%, the grain boundary This is because the strength is reduced, cracks are likely to occur, and abnormal damage is likely to occur.
A method for calculating the ratio of the length of the grain boundary where the Mn element exists to the total grain boundary length of the crystal grain will be described below. In addition to the grain boundary mapping by the high-resolution electron beam backscatter diffraction device described above, FE (Field Emission)-EPMA composition mapping was performed at the same time, and the total grain boundary of the crystal grains in which the Mn element was detected on the grain boundary. It can be obtained by calculating the length and calculating the proportion of the total grain boundary length. Note that the measurement interval of FE-EPMA is equal to or less than that of EBSD (0.02 μm interval or less).

Bottom layer and top layer:
In the present invention, by providing the TiAlMn(Si)CN layer as the hard coating layer, sufficient chipping resistance and wear resistance are obtained. provided with a lower layer comprising one or more layers of carbonitride oxide layers and containing a Ti compound layer having a total average layer thickness of 0.1 to 20.0 μm, and/or at least aluminum oxide When the upper layer including the layers is provided with a total average layer thickness of 1.0 to 25.0 μm, further excellent properties can be exhibited in combination with the effects of these layers.
Ti having a total average layer thickness of 0.1 to 20.0 μm consisting of one or more layers selected from a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer and a carbonitride layer When a lower layer containing a compound layer is provided, if the total average layer thickness of the lower layer is less than 0.1 μm, the effect of the lower layer is not sufficiently exhibited. , chipping is more likely to occur. Further, if the total average layer thickness of the upper layer including the aluminum oxide layer is less than 1.0 μm, the effect of the upper layer is not sufficiently exhibited, while if it exceeds 25.0 μm, the crystal grains tend to coarsen, causing chipping. more likely to occur.

Production method:
The TiAlMn(Si)CN layer of the present invention can be produced, for example, as follows.

A gas group A consisting of NH ₃ , H ₂ and N ₂ and AlCl ₃ , TiCl ₄ , C ₂ H ₄ , HCl, SiCl ₄ and Mn(C ₅ H ₅ ) were applied to the surface of the tool substrate using a CVD apparatus. ₂ , gas group B consisting of _H2 , and the method of supplying each gas, reaction gas composition (% by volume of the total of gas group A and gas group B), reaction atmosphere pressure, reaction atmosphere temperature, supply cycle, 1 A TiAlMn(Si)CN layer with a predetermined average layer thickness was formed using a thermal CVD method under the following film formation conditions for the gas supply time per cycle and the phase difference between the supply of gas group A and gas group B: .
Reaction gas composition (% represents volume %, and the sum of gas group A and gas group B is 100 volume %)
Gas group A: NH ₃ : 2.00 to 3.00%, H ₂ : 15.00 to 25.00%,
_N2 : 15.00 to 25.00%
Gas group B: AlCl ₃ : 0.50 to 1.00%, TiCl ₄ : 0.07 to 0.50%,
_C2H4 : 0.00-0.50%, HCl: 0.00-0.10% _,
SiCl4 : 0.00-0.20%,
Mn(C ₅ H ₅ ) ₂ : 0.01 to 0.20%, H ₂ : Residual reaction atmosphere pressure: 4.5 to 5.0 kPa
Reaction atmosphere temperature: 700-850°C
Supply cycle: 1.00 to 5.00 seconds Gas supply time per cycle: 0.15 to 0.25 seconds Supply phase difference between gas group A and gas group B: 0.10 to 0.20 seconds

Next, the coated tool of the present invention will be described in detail with reference to examples.
In the following examples, the case of using a WC-based cemented carbide as a tool substrate will be described, but the same applies to the case of using a TiCN-based cermet and a cBN-based ultrahigh-pressure sintered body as a tool substrate. Needless to say, the coated tool of the present invention can be suitably used not only for inserts but also for cutting tools such as drills, metal saws, reamers, and taps.

As raw material powders, WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder and Co powder, all having an average particle size of 0.1 to 3.0 μm, were prepared. The raw material powder was blended according to the formulation shown in Table 1, wax was added, and the mixture was mixed in a ball mill in acetone for 24 hours. The green compact is vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature within the range of 1370 to 1470° C. for 1 hour. and tool substrates D to F made of WC-based cemented carbide having an insert shape according to ISO standard CNMG120412.

Next, a TiAlMn(Si)CN layer was formed on the surfaces of these tool substrates A to F by CVD using a CVD apparatus.
CVD film formation conditions are as follows.
Formation conditions A to K shown in Table 3, that is, gas group A consisting of NH ₃ and H ₂ and N ₂ and AlCl ₃ , TiCl ₄ , C ₂ H ₄ , HCl, SiCl ₄ , Mn(C ₅ H ₅ ) ₂ , gas group B consisting of H ₂ , and as a method of supplying each gas, the reaction gas composition (% is the volume % of the total of gas group A and gas group B), and gas group A is NH ₃ : 2.00 to 3.00%, H ₂ : 15.00 to 25.00%, N ₂ : 15.00 to 25.00%, AlCl ₃ as gas group B: 0.50 to 1.00% , TiCl ₄ : 0.07-0.50%, C ₂ H ₄ : 0.00-0.50, HCl: 0.00-0.10%, SiCl ₄ : 0.00-0.20%, Mn (C ₅ H ₅ ) ₂ : 0.01-0.20%, H ₂ : balance, reaction atmosphere pressure: 4.5-5.0 kPa, reaction atmosphere temperature: 700-850° C., supply cycle 1.00-5 0.00 seconds, the gas supply time per cycle is 0.15 to 0.25 seconds, and the phase difference between gas group A and gas group B is 0.10 to 0.20 seconds. did

In this way, by performing the CVD method under the formation conditions shown in Table 3, the coated tools 1 to 22 of the present invention (the coated tool 4 of the present invention is a reference example, Hereinafter, the description of Reference Examples is omitted.) was obtained.
For the coated tools 1 to 11, 14, 15, 17 to 19, 21 and 22 of the present invention, the lower layer and/or the upper layer shown in Table 4 were formed under the formation conditions shown in Table 2.

For the purpose of comparison, the surfaces of the tool substrates A to F were subjected to the CVD method under the forming conditions A' to H' shown in Table 3 to obtain comparative coated tools 1 to 16 shown in Table 6. .
For comparative coated tools 2, 3, 5, 6, 8, 10, 14 and 16, the lower layer and/or the upper layer shown in Table 4 were formed under the formation conditions shown in Table 2.

The cross section (longitudinal cross section) of each component layer of the coated tools 1 to 22 of the present invention and the comparative coated tools 1 to 16 in the direction perpendicular to the tool substrate was measured using a scanning electron microscope (magnification: 5000 times), and the field of view was observed. When the average layer thickness was calculated by measuring the layer thickness at five points inside, the average layer thicknesses shown in Tables 5 and 6 were obtained.
In addition, the proportion and composition of crystal grains having a NaCl-type face-centered cubic structure, the average grain width W and the aspect ratio A of crystal grains having a columnar crystal structure were measured by the methods described above. The average grain width W and aspect A were measured at 20 points.
Regarding the atomic ratio β of Mn and the atomic ratio δ of Si, those described as less than 0.001 and less than 0.0001 in Tables 5 and 6, respectively, are contents below the detection limit, and Mn , and can be treated as not containing Si, and the comparative coated tools shown in Table 6 do not contain Mn and Si at the same time, so α/(1-δ), β/(1- δ) and (α+β)/(1−δ) are not determined.
In calculating the ratio of the length of the grain boundary where the Mn element exists to the total grain boundary length of the crystal grain, the FE-EPMA measurement was performed at intervals of 0.02 μm.

Next, the coated tools 1 to 11 of the present invention and the comparative coated tools 1 to 8 were measured in a state where each of the various coated tools was clamped to the tip of a tool steel cutter having a cutter diameter of 80 mm with a fixing jig. A dry high-speed face milling and center-cut cutting test, which is a type of high-speed interrupted cutting of cast iron, was performed, and the flank wear width of the cutting edge was measured.
<Cutting test 1>
Cutter diameter: 80mm
Work material: JIS FCD700 block material with a width of 60 mm and a length of 400 mm Rotational speed: 1393/min
Cutting speed: 350m/min
Notch: 2.0mm
Feed amount per blade: 0.2 mm/blade Cutting time: 20 minutes (normal cutting speed is 150 to 250 m/min)
Table 7 shows the results of the cutting test. The comparative coated tools 1 to 8 reached the end of their lives before the end of the cutting test due to the occurrence of chipping, so the time until the end of their lives is shown.

Next, in a state where each of the various coated tools is screwed to the tip of the tool steel cutting tool with a fixing jig, the coated tools 12 to 22 of the present invention and the comparative coated tools 9 to 16 are cast iron shown below. A dry high-speed intermittent turning test was performed on the 8-slit grooved material, and the flank wear width of the cutting edge was measured in each case.
<Cutting test 2>
Work material: JIS FCD700 8 grooves equally spaced in the length direction Cutting speed: 350m/min
Notch: 1.0mm,
Feed: 0.2mm/rev,
Cutting time: 5 minutes (normal cutting speed is 150-200m/min)
Table 7 shows the results of the cutting test. The comparative coated tools 9 to 16 reached the end of their lives before the end of the cutting test due to the occurrence of chipping, so the time until the end of their lives is shown.

As is clear from the results shown in Table 7, the coated tools of the present invention each contain a composite nitride layer or composite carbonitride layer of Ti, Al, Mn, and Si as an optional component, and have a composition within a predetermined range. It satisfies the prescribed relationship, and has a prescribed average grain width and average aspect ratio. Even when used for high-speed interrupted cutting, it exhibits excellent chipping resistance as a hard coating layer and exhibits excellent cutting performance over long-term use.
On the other hand, when the comparative coated tool that does not satisfy even one of the items specified in the coated tool of the present invention is used for high-speed interrupted cutting of alloy steel, cast iron, etc., chipping occurs and it can be used in a short time. has reached the end of its life.

As described above, the coated tool of the present invention exhibits excellent wear resistance over a long period of time even in high-speed interrupted cutting of alloy steel, cast iron, etc., where high loads act, so it is possible to improve the performance of cutting equipment. In addition, it is possible to fully satisfy labor saving and energy saving in cutting and cost reduction.

Claims (3)

A surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool substrate made of any one of a tungsten carbide-based cemented carbide, a titanium carbonitride-based cermet, and a cubic boron nitride-based ultrahigh-pressure sintered body,
(a) the hard coating layer includes at least a composite nitride layer or composite carbonitride layer of Ti, Al and Mn with an average layer thickness of 1.0 to 20.0 μm;
(b) The composite nitride layer or composite carbonitride layer of Ti, Al, and Mn has 70 areas of crystal grains having a NaCl-type face-centered cubic structure when analyzed from a longitudinal section perpendicular to the surface of the tool substrate. % or more, including
(c) The composite nitride layer or composite carbonitride layer of Ti, Al and Mn has a composition of
Composition formula: (Ti _1-α-β Al _α Mn _β ) (C _γ N _1-γ )
represented by the average content ratio α of Al in the total amount of Ti, Al and Mn, the average content ratio β of Mn in the total amount of Ti, Al and Mn, and the average of C in the total amount of C and N The content ratio γ (where α, β, and γ are all atomic ratios) is 0.500 ≤ α ≤ 0.900, 0.005 ≤ β ≤ 0.150, and 0.505 ≤ α + β ≤ 0.950, respectively and satisfies 0.0000 ≤ γ ≤ 0.0050,
(d) The crystal grains having the NaCl-type face-centered cubic structure of the composite nitride layer or composite carbonitride layer of Ti, Al, and Mn have a columnar crystal structure, and the area-weighted average of the crystal grains is The calculated average particle width W is 0.1 to 3.0 μm, the average aspect ratio A calculated by area weighted average is 2.0 to 10.0,
(e) When observing the longitudinal section of the composite nitride layer or composite carbonitride layer of Ti, Al, and Mn, Mn is present at the grain boundaries of the crystal grains having the NaCl-type face-centered cubic structure. And, the length of the grain boundary where Mn exists is 0.1 to 10.0% of the length of all grain boundaries of the crystal grains having the NaCl type face-centered cubic structure. Surface coated cutting tools. The composite nitride layer or composite carbonitride layer of Ti, Al, and Mn contains a trace amount of Cl, and the content ratio ε of Cl in the total amount of C, N, and Cl (where ε is the atomic ratio) is The surface-coated cutting tool according to claim 1 , wherein 0.0001≤ε≤0.0020 is satisfied. The composite nitride layer or composite carbonitride layer of Ti, Al, and Mn further contains Si, and its composition is
Composition formula: (Ti _1-α-β-δ Al _α Mn _β Si _δ ) (C _γ N _1-γ )
represented by the average content ratio α of Al in the total amount of Ti, Al, Mn and Si, the average content ratio β of Mn in the total amount of Ti, Al, Mn and Si, and the total amount of C and N of C When the average content ratio γ in the amount and the average content ratio δ in the total amount of Ti, Al, Mn and Si of Si (where α, β, γ, and δ are all atomic ratios), Ti in Al and Average content ratio α / (1-δ) in the total amount of Al and Mn, average content ratio β / (1-δ) in the total amount of Ti, Al and Mn in Mn, Ti and Al and Mn in Si The average content ratio δ in the total amount of Si and the average content ratio γ of C in the total amount of C and N are 0.500≦α/(1−δ)≦0.900 and 0.005≦β, respectively. / (1-δ) ≤ 0.150, 0.005 ≤ δ ≤ 0.150 and 0.505 ≤ (α + β) / (1-δ) ≤ 0.950, 0.0000 ≤ γ ≤ 0.0050 to do
The surface-coated cutting tool according to claim 1 or 2 , characterized by: