Surface-coated cutting tool

Abstract

Provided is a surface-coated cutting tool comprising a plurality of identically-shaped cutting blade tips, wherein: a coating layer of each flank surface is (AlxTi1-x)(CyN1-y) (where the average content xavg of x is 0.60-0.95, and the average content yavg of y is 0.0000-0.0050); when the average value of the 200 diffracted ray intensity of crystal grains of a NaCl-type face-centered cubic structure in each flank surface is defined as I(200) and the standard deviation thereof is defined as σI(200), σI(200) / I(200) is 0.00-0.20; when the thickness of the coating layer on a line 100 μm away from each cutting blade tip ridge part in the flank surface direction is defined as Lm, the average value thereof is defined as Lavg, and the standard deviation thereof is defined as σL, σL / Lavg is 0.00-0.20; on each flank surface the coating layer includes a columnar crystal; there is a region where the content of Al and Ti changes; and the difference between the maximum value xmax and the minimum value xmin of x is 0.02-0.40.

Description

surface coated cutting tools

[0001] The present invention relates to a surface-coated cutting tool (hereinafter sometimes referred to as a coated tool). This application claims priority to Japanese Patent Application No. 2022-56507, filed on March 30, 2022. The entire contents of said Japanese patent application are incorporated herein by reference.

[0002] Coated tools, which have a coating layer formed on the surface of a substrate such as a tungsten carbide (hereinafter referred to as WC)-based cemented carbide, are known as cutting tools. In order to ensure uniform cutting performance across multiple cutting edges of the coated tool, efforts have been made to make the composition of the coating layer uniform.

[0003] For example, Patent Document 1 describes a chemical vapor deposition apparatus capable of forming a coating layer with a uniform composition on a plurality of substrates placed on a jig, and claims that by forming a film using this apparatus, a coated tool can be obtained that has a coating layer with a uniform composition, with a small difference in the average Al or Ti content between the coating layers formed on the substrates on the inner periphery of the jig and the outer periphery of the jig.

[0004] Japanese Patent Application Laid-Open No. 2017-20111

[0005] The present invention has been made in consideration of the above circumstances and proposals, and aims to provide a coated tool that defines the degree of uniformity of a coating layer and ensures that all of a plurality of cutting edges of the same shape have a sufficient and uniform service life even in high-speed intermittent cutting.

[0006] A surface-coated cutting tool according to an embodiment of the present invention has a substrate and a coating layer provided on the substrate, (a) the coating layer includes a composite nitride layer or composite carbonitride layer of Al and Ti having crystal grains of a face-centered cubic structure of NaCl, (b) the tool has a plurality of cutting edges of the same shape, and on the flank faces of all the cutting edges, the composite nitride layer or composite carbonitride layer of Al and Ti is ｘ Ti １－ｘ ) (C ｙ N １－ｙ ) (average content of x x ａｖｇ is 0.60 or more and 0.95 or less, and the average content of y ａｖｇ(c) on each of the flank faces of all the cutting edges, the crystal grains having the NaCl type face-centered cubic structure contained in the coating layer have 200 diffraction lines measured using an X-ray diffractometer, and the average intensity value of the 200 diffraction lines is I ａｖｇ (200), and its standard deviation is σ I（２００） Then, σ I（２００） / I ａｖｇ (200) satisfies 0.00 or more and 0.20 or less, (d) for each of all the cutting edges, the thickness Lm of the coating layer on a line 100 μm away from the ridge of the cutting edge in the flank direction, and the average value of Lm for all the cutting edges ａｖｇ , standard deviation is σ Ｌ Then, σ Ｌ / L ａｖｇ (e) on each flank face of all the cutting edges, the Al and Ti composite nitride layer or composite carbonitride layer contains columnar crystals, and the maximum value x of X in the columnar crystals is ｍａｘ * is the average value of x ｍａｘ and the minimum value x of X ｍｉｎ * is the average value of x ｍｉｎ is 0.02≦x ｍａｘ -x ｍｉｎ ≦0.40

[0007] Furthermore, the surface-coated cutting tool according to the above embodiment may satisfy one or more of the following items (1) to (5).

[0008] (1) TC (200), which is the average value of the orientation index TC of the crystal grains having the NaCl-type face-centered cubic structure contained in the coating layer on each of the flank faces of all the cutting edges. ａｖｇ (200) satisfies the condition of 1.0 or more and 6.0 or less.

[0009] (2) For each of the cutting edges, the average value of the orientation index TC(200) of the crystal grains having the NaCl type face-centered cubic structure contained in the coating layer is calculated as TC ａｖｇ (200), and its standard deviation is σ ＴＣ（２００） Then, σ ＴＣ（２００） / TC ａｖｇ(200) is 0.00 or more and 0.10 or less.

[0010] (3) On each of the flank faces of all the cutting edges, the area in which the Al and Ti contents contained in the coating layer change is present in 70% or more of the area of ​​the longitudinal cross section of the coating layer.

[0011] (4) In each of the coating layers of all the cutting edges, the average grain width W of the columnar crystals of the Al and Ti composite nitride layer or composite carbonitride layer is 0.10 μm or more and 1.20 μm or less, and the average aspect ratio A is 2.0 or more and 10.0 or less.

[0012] (5) The Al and Ti composite nitride layer or composite carbonitride layer contains chlorine, and the content of chlorine is 0.005 atomic % or more and 0.500 atomic % or less.

[0013] The surface-coated cutting tool has excellent coating uniformity, and all cutting edges thereof exhibit excellent resistance to heat cracking and chipping even when cutting alloy steel, carbon steel, or cast iron at high speeds and with interrupted cutting.

[0014] FIG. 5 is a cross-sectional view schematically illustrating an example of a cutting edge ridge portion at the cutting edge of the insert. FIG. 6 is a view schematically illustrating an example of a corner portion of the cutting edge at the cutting edge of the insert. FIG. 7 is a schematic diagram showing a plan view of an example of the arrangement of gas supply pipes in a chemical vapor deposition apparatus for manufacturing the surface-coated cutting tool according to the present embodiment. FIG. 8 is a schematic diagram showing a side view of the apparatus described in FIG. 3. FIG. 9 is a schematic diagram of a chemical vapor deposition apparatus in which a surface-coated cutting tool of a comparative example was manufactured. FIG. 10 is a schematic diagram of a cross section of a gas supply pipe in the apparatus described in FIG.

[0015] When a coated tool is used in high-speed interrupted cutting, if the coating layer is non-uniform, i.e., if the thickness, composition, etc. of the coating layer are non-uniform, the non-uniform parts become the origin of fracture, resulting in thermal cracking and chipping. In particular, when one coated tool has multiple cutting edges, if the coating layer on each cutting edge is not uniform, the cutting performance of the cutting edges will vary, resulting in differences in durability.

[0016] The present inventors have investigated the variations in cutting performance and differences in durability among cutting edges, and have found that, in a coating layer having an Al-Ti composite nitride or composite carbonitride (hereinafter, these composite nitrides and composite carbonitrides may be collectively referred to as AlTiCN), when crystal grains having a {111} plane preferred orientation and crystal grains having a {100} plane preferred orientation are mixed, or when crystal grains having a {100} plane preferred orientation that tend to contain hexagonal crystal grains at grain boundaries, etc., exist, the growth rate of the crystal grains differs depending on the orientation and crystal system. Therefore, when one coated tool has multiple cutting edges, the uniformity of the thickness, orientation, and crystallinity of the coating layer among the cutting edges decreases, causing variations in cutting performance and differences in durability.

[0017] Meanwhile, the present inventors have investigated film formation using the vapor deposition apparatus described in Patent Document 1. As a result, they have recognized that even if this vapor deposition apparatus is used, in a coated tool having multiple cutting edges including coating layers with different crystal grain growth rates, it is not possible to sufficiently equalize the thickness, orientation, and crystallinity of the coating layers on the multiple flank faces. That is, when this coated tool is used in high-speed intermittent cutting of carbon steel, cast iron, or alloy steel, it is not possible to prevent the occurrence of cutting edges that have a shorter service life than the other cutting edges, and uniform durability may not be achieved.

[0018] Based on this recognition, the present inventors have concluded that in order to obtain uniform thermal crack resistance and chipping resistance in a coated tool having multiple cutting edges with a coating layer containing crystal grains with different grain growth rates in high-speed interrupted cutting of carbon steel, cast iron, or alloy steel, it is essential to specify the allowable limits (tolerable degree of non-uniformity) of the thickness, orientation, and crystallinity of the coating layer, particularly on the flank face. Therefore, the present inventors have conducted extensive research into the allowable limits of the uniformity of the thickness and orientation of the coating layer on the flank faces of multiple cutting edges, and have obtained knowledge regarding these allowable limits. Furthermore, they have also obtained knowledge regarding the physical properties required of the coating layer when a coated tool having multiple cutting edges with the aforementioned coating layers with different grain growth rates is used in high-speed interrupted cutting of carbon steel, cast iron, or alloy steel.

[0019] Hereinafter, embodiments of the present invention will be described in detail.

[0020] In this specification and claims, when a numerical range is expressed as "L to M" (where L and M are both numerical values), this is synonymous with "not less than L and not more than M," and the range includes an upper limit (M) and a lower limit (L). When a unit is stated only for the upper limit (M), the upper limit (M) and the lower limit (L) have the same unit.

[0021] First, definitions of terms related to the coated tool of this embodiment will be provided.

[0022] The term "high-speed intermittent cutting" as used herein refers to cutting performed at a speed higher than that normally performed by those skilled in the art, in which the cutting edge of the cutting tool alternates between cutting and idling.

[0023] In this specification and claims, the term "longitudinal cross section" refers to a cross section perpendicular to the surface of the substrate when the substrate is treated as a flat surface, ignoring minute irregularities on the surface of the substrate. In this specification, the substrate surface refers to the average line (straight line) of the interface roughness between the substrate and the coating layer in the observed image of the longitudinal cross section. The direction perpendicular to this average line is the direction perpendicular to the substrate (thickness direction of the coating layer). Even when the substrate has a curved surface, such as a drill, if the tool diameter is sufficiently large relative to the thickness of the coating layer, the interface between the coating layer and the substrate in the measurement area will be approximately flat, and the surface of the substrate can be determined using a similar method.

[0024] In the present specification and claims, the cutting edge refers to the part that comes into contact with the workpiece when actually used in cutting.

[0025] 1. Coating Layer The coating layer of this embodiment includes an AlTiCN layer, which will be described in detail below.

[0026] (1) Crystal grains with a NaCl-type face-centered cubic structure When a single coated tool contains multiple cutting edges with the same shape, the AlTiCN layer contained in the coating layer on the flank faces of all of the cutting edges preferably contains crystal grains with a NaCl-type face-centered cubic structure. Furthermore, for all of the multiple cutting edges, the area ratio of crystal grains with a NaCl-type face-centered cubic structure in the longitudinal cross section of the coating layer on the flank face is preferably 50 area% or more, more preferably 70 area% or more. This is because, while a ratio of 50 area% or more can solve the aforementioned problem, a ratio of less than 70 area% can result in low hardness and insufficient wear resistance. All of the crystal grains may have a NaCl-type face-centered cubic structure (100 area%).

[0027] The presence or absence of crystal grains of the NaCl type face-centered cubic structure that constitutes the AlTiCN layer can be confirmed, for example, by measuring the X-ray diffraction pattern using micro-X-ray diffraction measurement (examples of measurement conditions: Cu-Kα radiation, output 50 kV, 22 mA, step size 0.02 mm, scan step time 300 sec, detection distance 150 mm, collimator diameter 100 μmΦ) and checking the presence or absence of X-ray diffraction peaks that appear between the diffraction angles of the same crystal planes shown in JCPDS00-038-1420 cubic TiN and JCPDS00-046-1200 cubic AlN (for example, 36.66 to 38.53°, 43.59 to 44.77°, 61.81 to 65.18°).

[0028] Furthermore, the presence or absence of crystal grains of the NaCl type face-centered cubic structure that constitute the AlTiCN layer may be confirmed in conjunction with the method for determining the area ratio of crystal grains of the NaCl type face-centered cubic structure that constitute the AlTiCN layer, which will be described below. The measurement location is preferably an observation field in the vicinity of the measurement position (within a radius of 50 μm from this measurement position) where the average thickness (Lm) of the AlTiCN layer on the flank face, which will be described later, is determined for each cutting edge.

[0029] The procedure for measuring the area ratio of crystal grains with a face-centered cubic structure of NaCl is as follows: First, the crystal grain boundaries are identified. That is, a longitudinal section is polished to obtain a polished surface, and using a crystal orientation analyzer attached to a transmission electron microscope (TEM), an electron beam tilted, for example, at an angle of 0.5 degrees or more and 1.0 degrees or less with respect to the normal direction of the polished surface is irradiated in a precession motion. The electron beam is scanned at a given beam diameter and interval for each measurement point, and electron diffraction patterns are continuously captured.

[0030] By analyzing each measurement point, the presence or absence of a NaCl-type face-centered cubic structure and its crystal orientation can be determined. Then, for an observation field set to a width of 2000 nm and a height that includes the entire thickness of the coating layer, the grain boundaries are determined as described below.

[0031] The conditions for acquiring the electron diffraction pattern used in the measurement are, for example, an acceleration voltage of 200 kV, a camera length of 20 cm, a beam size of 2.4 nm, and a measurement step of 10.0 nm in both the horizontal and vertical directions. The measured crystal orientations are measured discretely on the measurement surface, and the measurement results are used to represent the region up to the middle between adjacent measurement points, thereby obtaining the orientation distribution for the entire measurement surface. The region represented by the measurement points (hereinafter sometimes referred to as a pixel) can be, for example, a square.

[0032] When the difference in the crystal orientation between adjacent pixels is 5 degrees or more, or when only one of the adjacent pixels exhibits a NaCl-type face-centered cubic structure, the edge of the region where these pixels meet is taken as a grain boundary, and the region surrounded by this grain boundary edge is defined as one crystal grain.

[0033] However, pixels that exist alone and have an orientation difference of 5 degrees or more with all adjacent pixels, or pixels that do not have adjacent measurement points with a NaCl-type face-centered cubic structure, are not considered to be crystal grains, but pixels that are connected to two or more pixels are treated as crystal grains. In this way, grain boundary determination is performed and crystal grains are identified.

[0034] The area ratio of the crystal grains having the NaCl-type face-centered cubic structure is calculated as the ratio of the total area of ​​the crystal grains having the specified NaCl-type face-centered cubic structure to the total area of ​​the observation field. Similar measurements are performed on five or more observation fields for each cutting edge, and the average value of the measurement results for all cutting edges is taken as the area ratio of the crystal grains having the NaCl-type face-centered cubic structure that constitute the AlTiCN layer.

[0035] (2) Composition of the AlTiCN layer On each of the flank faces of all the cutting edges, the AlTiCN layer has a composition of (Al ｘ Ti １－ｘ ) (C ｙ N １－ｙ ), (average content of x x ａｖｇ is 0.60 or more and 0.95 or less, and the average content of y ａｖｇ is preferably 0.0000 or more and 0.0050 or less.

[0036] x ａｖｇ The reason for setting x in this range is that ａｖｇ If x is less than 0.60, the heat crack resistance decreases, which is not preferable. ａｖｇ If y exceeds 0.95, the abrasion resistance decreases, which is not preferable. ａｖｇ The reason why the average content x is set to this range is that when it is in this range, the lubricity is improved, the impact during cutting is alleviated, and chipping resistance is improved. ａｖｇ When is 0.75 or more and 0.95 or less, the above-mentioned properties can be more excellently exhibited.

[0037] x relating to the average content of the AlTiCN layer ａｖｇ , y ａｖｇ The measurement location is preferably an observation field in the vicinity of a measurement position (within a radius of 50 μm from this measurement position) where the average thickness (Lm) of the AlTiCN layer on the flank face, which will be described later, is determined for each cutting edge.

[0038] The content (x) of Al in the total amount of Al and Ti can be determined, for example, by using an electron probe microanalyzer (EPMA) to irradiate an electron beam from the surface side of the longitudinal section near the measurement position on a polished surface of the coating layer, and then averaging the obtained characteristic X-ray analysis results at 10 points. Alternatively, it can be determined from the analysis results of the Al and Ti compositions obtained by irradiating an electron beam from the longitudinal section on the polished surface of the coating layer near the measurement position on the longitudinal section using energy dispersive X-ray spectroscopy (EDS), and performing line analysis in the thickness direction of the layer.

[0039] The C content (y) is determined, for example, by measuring the C concentration in the depth direction by secondary ion mass spectroscopy (SIMS) in a 70 μm×70 μm region of the polished surface of the coating layer parallel to the substrate surface near the measurement position, and calculating the average value. These average values ​​are then measured at multiple locations (e.g., three locations) on all the coating layers on the cutting edges of the same shape present in one coated tool, and the y value is calculated by averaging all of these measurement results. ａｖｇ Let's say.

[0040] In addition, (Al ｘ Ti １－ｘ ) and (C ｙ N １－ｙ The ratio of Al to Al is not particularly limited. ｘ Ti １－ｘ ) is set to 1, (C ｙ N １－ｙ The ratio of (Al) to (Al) is preferably 0.8 or more and 1.2 or less. ｘ Ti １－ｘ ) to (C ｙ N １－ｙ ) within the above range, the above-mentioned object can be more reliably achieved.

[0041] Furthermore, even if the AlTiCN layer contains a small amount of unavoidable impurities (impurities that are unintentionally contained) such as oxygen, this does not hinder the achievement of the above-mentioned object.

[0042] (3) Average value and standard deviation of 200 diffraction line intensity of crystal grains having a NaCl type face-centered cubic structure in the AlTiCN layer. For each of the flanks of all cutting edges, the crystal grains having the NaCl type face-centered cubic structure contained in the coating layer measured using an X-ray diffractometer have 200 diffraction lines, and the average value of the 200 diffraction line intensity values ​​is I ａｖｇ (200), and its standard deviation is σ I（２００） Then, σ I（２００） / I ａｖｇ It is preferable that (200) is 0.00 or more and 0.20 or less.

[0043] The reason is that it is preferable that there is no variation in the average value of the 200 diffraction ray intensity values, that is, the standard deviation σ is 0 (or not 0). I（２００） The lower limit of / I(200) is 0.00, while σ I（２００） / I ａｖｇ When the (200) exceeds 0.20, the crystallinity and uniformity of the orientation of each cutting edge deteriorate, and the uniformity of the thermal crack resistance and chipping resistance deteriorates when subjected to high-speed interrupted cutting. Here, the 200 diffraction line refers to the reflection indexed as 200 when performing XRD analysis.

[0044] The average value I of the 200 diffraction line intensity values ​​of the crystal grains having the NaCl type face-centered cubic structure ａｖｇ (200) and its standard deviation is σ I（２００） can be obtained for each cutting edge as follows: The X-ray diffraction pattern is measured by micro X-ray diffraction measurement (example of measurement conditions: Cu-Kα ray, output 50 kV, 22 mA, step size 0.02 mm, scan step time 300 sec, detection distance 150 mm, collimator diameter 100 μmΦ), and the 200 diffraction line intensity value is obtained. In this way, I(200) is obtained for each cutting edge, and these are averaged to obtain I ａｖｇ The measurement position is determined by selecting a line segment 500 μm from the cutting edge ridge and moving this line segment in parallel by 100 μm in the flank direction to obtain a position near the center of the line segment.

[0045] Here, if n is the number of cutting edges with the same shape, the standard deviation σ I（２００） can be calculated using the following [Equation 1].

[0046]

[0047] (4) Average value and standard deviation of the thickness of the AlTiCN layer on the flank For each of all the cutting edges, the average thickness Lm of the AlTiCN layer on a line 100 μm away from the ridge of the cutting edge in the flank direction was determined, and the average value Lm ａｖｇ and standard deviation σ Ｌ Then, σ Ｌ / L ａｖｇ It is preferable that the value satisfies the range of 0.00 to 0.20.

[0048] L ａｖｇ The reason is that within this range, sufficient wear resistance can be ensured and excellent chipping resistance can be obtained. ａｖｇ When the thickness is 3.0 μm or more and 15.0 μm or less, the above-mentioned properties can be more excellently exhibited.

[0049] The reason is that L ａｖｇ There is no variance, i.e., the standard deviation σ Ｌ is preferably 0 (or not), so σ Ｌ The lower limit of / Lavg is 0.00, while σ Ｌ If / Lavg is greater than 0.20, a distribution in the thickness of the coating layer occurs due to differences in the film formation speed, and the uniformity of the thermal crack resistance and chipping resistance decreases when subjected to high-speed intermittent cutting.

[0050] Here, the cutting edge ridge portion of the cutting edge is the point on the surface of the coating layer (indicated by the dotted arrow) that is closest to the intersection of the approximate straight line (hereinafter sometimes referred to as the approximate straight line) on the rake face (1) and the flank face (2), as shown in Figure 1, within the area connecting the points where the rake face (1) and the flank face (2) are separated from the straight line and the bending begins (i.e., the area from the bending point on the rake face to the bending point on the flank face on the surface of the coating layer).

[0051] In this embodiment, a coated tool including a plurality of cutting edges of the same shape is targeted, and in all of the cutting edges, the average thickness Lm of the coating layer on a line 100 μm away from the ridge of the cutting edge in the flank face direction, and the average value L of this Lm ａｖｇ and standard deviation σ Ｌ It is required as follows:

[0052] As shown in Figure 2, when viewed from the rake face (1), the cutting edge ridge is the cutting edge ridge (3) of the main cutting edge. The line 100 μm away from the cutting edge ridge in the flank direction refers to a straight line parallel to the cutting edge ridge (3) of the main cutting edge, starting from an arbitrary point on the cutting edge ridge (3) of the main cutting edge and passing through a point 100 μm away in the flank direction.

[0053] Specifically, in FIG. 2, a line segment 500 μm from the cutting edge ridgeline (3) is selected, and the line segment is translated in parallel by 100 μm in the flank direction, and multiple points on the line segment spaced apart by a predetermined distance are selected to measure the thickness of the coating layer, and the average value Lm is calculated.

[0054] Here, the plurality of points on the line segment spaced apart by a predetermined distance can be, for example, four points spaced apart by 30 μm, but it is not limited to this and it is preferable to select more measurement points. In this way, Lm is calculated for each cutting edge, and the average is calculated to obtain L ａｖｇ Ask for.

[0055] In measuring the thickness, a sample for observing the longitudinal cross section of the coating layer is prepared using a cross section polisher (CP) or the like, and the cross section is observed using a scanning electron microscope (SEM).

[0056] Here, if n is the number of cutting edges with the same shape, the standard deviation σ Ｌ can be calculated using the following [Equation 2].

[0057]

[0058] In addition, when a single coated tool contains multiple cutting edges of the same shape with two types of corners, one with an acute angle and the other with an obtuse angle, if either of them satisfies the requirements described in this specification and claims, it will be treated as a surface-coated cutting tool of the present invention.

[0059] Furthermore, for circular inserts, when the cutting edge is located along the outer periphery of the circle, two points can be selected, for example, an arbitrary point on the circumference and a point located 180 degrees rotated from the center of the circle as the starting point, and each can be considered to be a cutting edge of the same shape, and the above-mentioned standard deviation can be calculated.

[0060] (5) The change in the content of Al and Ti, including columnar crystals, and the maximum value of x ｍａｘ and the minimum value x ｍｉｎ , and the area ratio S of the region having this change. In each of all cutting edge flanks, the AlTiCN layer contains columnar crystals and contains a change in the content of Al and Ti, and the maximum value x of the content (ratio) (x) of Al to the total amount of Ti and Al in this content change. ｍａｘ and the minimum value x ｍｉｎ However, 0.02≦x ｍａｘ -x ｍｉｎ It is preferable that the relationship ≦0.40 is satisfied. Note that the columnar crystals refer to crystal grains in the AlTiCN layer having an aspect ratio A (defined later) of 1.5 or more.

[0061] x ｍａｘ -x ｍｉｎ When the value of β is within this range, the thermal cracking resistance and chipping resistance of the coated tool are improved. However, when the value is less than 0.02, the improvement is insufficient, and when the value is greater than 0.40, the strain within the crystal grains constituting the AlTiCN layer becomes too large, resulting in a decrease in the thermal cracking resistance and chipping resistance of the coated tool.

[0062] Furthermore, on each of the cutting edge flanks, the region containing the change in Al and Ti content (described in detail below) preferably accounts for 50 area% or more, and more preferably 70 area% or more, of the longitudinal cross section of the AlTiCN layer. The reason for this is that, although the above-mentioned problem can be solved if the region containing the change in Al and Ti content is 50 area% or more, if it is less than 70 area%, the thermal crack resistance and chipping resistance of the coated tool may be reduced when subjected to high-speed interrupted cutting. The region containing the change in Al and Ti content may also account for 100 area% of the longitudinal cross section of the coating layer.

[0063] At each cutting edge, the maximum value x of the content of Al in the total amount of Ti and Al in the change in the content of Al and Ti ｍａｘ and the minimum value x ｍｉｎ The area ratio of the region containing the change in the Al and Ti contents in the coating layer can be calculated, for example, as follows.

[0064] The cross section of the coating layer is observed at an appropriate magnification of 160,000 to 320,000 times using an energy dispersive X-ray spectrometer attached to a scanning transmission electron microscope (STEM).

[0065] Then, in the longitudinal cross section of the coating layer, the Al content (x) of the Al relative to the total amount of Ti and Al is determined over the entire rectangular observation field, which has a width of 2 μm or more in the direction parallel to the surface of the substrate and is set so as to include the entire thickness of the coating layer. The observation field is preferably near the measurement position (within a circle with a radius of 50 μm from this measurement position) where the average thickness (Lm) of the AlTiCN layer on the flank face of each cutting edge is determined.

[0066] For each crystal grain (columnar crystal) of the NaCl type face-centered cubic structure and hexagonal structure contained in the entire observation field, the distribution of the Al content (x) in the total amount of Ti and Al was obtained, and the maximum value x ｍａｘ * and minimum x ｍｉｎ * are the average values ​​(x ａｖｇ *) is determined to contain changes in the content of Al and Ti.

[0067] That is, the region containing the change in the content of Al and Ti refers to a region that includes (sums up) all the crystal grains that are determined to contain the change in the content of Al and Ti. ｍａｘ *, minimum value x ｍｉｎ *The average value of each is the maximum value x at a cutting edge. ｍａｘ , minimum value x ｍｉｎ Let's say.

[0068] In addition, in the region including the change in the content of Al and Ti, the average value (x ａｖｇ It is more preferable that regions having a difference of +1% or more with respect to the average particle diameter (A) (high Al content regions) and regions having a difference of -1% or more with respect to the average particle diameter (A) (*) are distributed in a mesh, layer, or granular pattern. Furthermore, it is even more preferable that the minimum distance between the outer edges of high Al content regions separated by low Al content regions, or between the outer edges of low Al content regions separated by high Al content regions, is 1 nm or more and less than 50 nm.

[0069] The reason is that when the minimum value of the interval between the changes in the Al and Ti contents is within this range, the thermal cracking resistance and chipping resistance of the coated tool are improved, but if it is less than 1 nm, the improvement in thermal cracking resistance may not be sufficient, and if it is 50 nm or more, the improvement in chipping resistance may not be sufficient.

[0070] The ratio of the total area of ​​the crystal grains determined to contain the changes in Al and Ti content in the observation field is defined as the area ratio of the region containing the changes in Al and Ti content in the coating layer.

[0071] (6) The average value of the orientation index TC(200) (TC ａｖｇ (200)) For each of the cutting edges, the orientation index TC(200) of the crystal grains having the NaCl type face-centered cubic structure on a line 100 μm away from the cutting edge ridge in the flank direction is calculated, and the average value of the orientation index TC(200) is ａｖｇ It is more preferable that (200) satisfies 1.0 or more and 6.0 or less.

[0072] The reason is that T.C. ａｖｇIf (200) is less than 1.0, the thermal crack resistance at each cutting edge may be reduced when subjected to high-speed interrupted cutting. ａｖｇ The larger (200) is, the better, and the maximum value by definition may be 6.0. ａｖｇ When (200) is 1.0 or more and 3.4 or less, the balance between thermal crack resistance and wear resistance is excellent, and TC ａｖｇ When (200) is more than 3.5 and not more than 6.0, the heat crack resistance is excellent.

[0073] (7) Variation of the orientation index TC(200) σ ＴＣ（２００） / TC ａｖｇ It is more preferable that (200) satisfies 0.00 or more and 0.10 or less. The reason is that σ ＴＣ（２００） / TC ａｖｇ If (200) is greater than 0.10, the uniformity of thermal crack resistance and chipping resistance at each cutting edge may decrease when subjected to high-speed intermittent cutting.

[0074] The orientation index TC(200) is determined as follows. When a coated tool contains multiple cutting edges, a line segment 500 μm from the cutting edge ridge is selected for each cutting edge, and the measurement position is near the center of the line segment, which is translated 100 μm in the flank direction. At this measurement position, an X-ray diffraction pattern is measured by micro-area X-ray diffraction measurement (example measurement conditions: Cu-Kα radiation, output 50 kV, 22 mA, detection distance 150 mm, collimator diameter 100 μm).

[0075] When the 200 diffraction line of the crystal grains having the NaCl type face-centered cubic structure is visible, the orientation index TC(200) is calculated, and the average value of each at each cutting edge is calculated as TC(200). ａｖｇ (200), and the respective standard deviations σ ＴＣ（２００） Ask for.

[0076] Here, the orientation index TC(200) is defined as follows: TC(200)={I(200) / I ０ (200)} × [(1 / 6)×Σ{I(hkl) / I ０ (hkl)}]－１ The average value of the measured values ​​for each cutting edge is TC. ａｖｇ (200).

[0077] I(200): Measured value of X-ray diffraction peak intensity in the 200 diffraction line, I ０ (200): The average value of the standard X-ray diffraction peak intensity in the 200 diffraction line of the crystal plane of AlN described in JCPDS card 00-046-1200, Σ(I(hkl) / I ０ (hkl)): The sum of the values ​​of the ([measured value of X-ray diffraction peak intensity] / [average value of each standard diffraction peak intensity of AlN listed on the ICDD card]) of each of the diffraction lines of 111, 200, 220, 311, 222, and 400.

[0078] (8) Average grain width and average aspect ratio of columnar crystals The AlTiCN layer contains columnar crystals on the flank faces of all the cutting edges, and it is more preferable that the average grain width W of the columnar crystals in the longitudinal cross section is 0.1 μm or more and 2.0 μm or less, and the average aspect ratio A is 2.0 or more and 10.0 or less.

[0079] The reason for this is as follows: when the average grain width W is less than 0.1 μm, fine crystals may increase the number of grain boundaries, resulting in a decrease in plastic deformation resistance and a decrease in oxidation resistance, which may lead to abnormal damage, while when the average grain width W is greater than 2.0 μm, the toughness may be easily reduced due to the presence of coarsely grown grains.

[0080] Furthermore, when the average aspect ratio A of the crystal is smaller than 2.0, the interface is likely to become the fracture origin for the shear stress generated on the surface of the AlTiCN layer during cutting, which may cause chipping. Also, when the average aspect ratio A exceeds 10.0, minute chipping occurs on the cutting edge during cutting, and when chipping occurs in the adjacent columnar crystal structure, the resistance to the shear stress generated on the surface of the AlTiCN layer is likely to be small, causing the columnar crystal structure to break and the damage to progress rapidly, resulting in large chipping.

[0081] Next, we will explain how to calculate the average grain width W and average aspect ratio A of crystal grains having an NaCl-type face-centered cubic structure for each cutting edge. First, a longitudinal section of the AlTiCN layer is polished using the aforementioned method. The observation field is near the measurement position (within a circle with a radius of 50 μm from this measurement position) where the average thickness (Lm) of the AlTiCN layer on the flank face is determined for each cutting edge. It is a rectangle set to include the entire thickness of the coating layer, and is preferably large enough to include 20 or more crystal grains having an NaCl-type face-centered cubic structure.

[0082] As described above, the grain boundary is determined and the crystal grain is identified. Next, image analysis is performed to determine the maximum length H of the crystal grain ik at a certain cutting edge k in the direction perpendicular to the surface of the base (the surface of the base is treated as a flat surface). ｉｋ , the grain width W, which is the maximum length of the crystal grain ik in the direction parallel to the substrate; ｉｋ , and the area S of the grain i ｉｋ The aspect ratio A of the crystal grain i is measured. ｉｋ is A ｉｋ = H ｉｋ / W ｉｋ It is calculated as follows.

[0083] <Average grain width W> The grain width (W) measured for 20 or more crystals in the observation field for each cutting edge k １ From W ｊ , 1≦i≦jk, jk is the number of crystal grains for each cutting edge. jk≧20) is area-weighted averaged using [Equation 3] to obtain the average grain width Wk at a certain cutting edge k. Note that jk may be the same number for all cutting edges.

[0084]

[0085] <Average aspect ratio> For each cutting edge k, the aspect ratio A is calculated for 20 or more crystals in the observation field according to the above definition. ｊk (1≦i≦jk, jk≧20) is calculated, and the area-weighted average is calculated using [Equation 4] to obtain the average aspect ratio Ak at a certain cutting edge k.

[0086]

[0087] (9) Chlorine Content: The AlTiCN layer may contain chlorine (Cl). If it does, the average Cl content is preferably 0.005 atomic % or more and 0.500 atomic % or less. Here, the average Cl content is defined as (number of Cl atoms) / (number of Cl atoms + number of Al atoms + number of Ti atoms + number of C atoms + number of N atoms) × 100.

[0088] The reason why the average content of chlorine when contained is set to the above range is that within this range, the lubricity can be reliably increased without reducing the toughness of the AlTiCN layer.

[0089] The average chlorine content in the AlTiCN layer is determined as follows. For example, using an electron probe microanalyzer (EPMA), a longitudinal section of a polished surface is irradiated with an electron beam, and the chlorine content is determined from the characteristic X-ray analysis results obtained. The observation field is preferably near the measurement position (within a circle with a radius of 50 μm from the measurement point) where the average thickness (Lm) of the AlTiCN layer on the flank face is determined for each cutting edge. Multiple locations (e.g., three locations) are observed in the coating layers on all cutting edges of the same shape present in a coated tool, and the average chlorine content for each cutting edge is determined.

[0090] 2. Other layers

[0091] 2-1. Lower layer Although the AlTiCN layer alone has sufficient durability, a lower layer consisting of one or more Ti compound layers selected from Ti nitride layers, carbide layers, and carbonitride layers (the compositions of these layers are not limited to stoichiometric compositions; any known composition may be used), having a total average thickness of 0.1 μm or more and 2.0 μm or less, may be provided adjacent to the substrate between the AlTiCN layer and the substrate. The lower layer improves adhesion between the AlTiCN layer and the substrate.

[0092] 2-2. Upper Layer An upper layer may be provided on the AlTiCN layer, which comprises one or more Ti compound layers selected from the group consisting of a nitride layer, a carbide layer, a carbonitride layer, and an oxide layer of Ti, and an aluminum oxide layer (the compositions of these layers are not limited to stoichiometric compositions; any known compositions may be used), and has a total average thickness of 0.1 μm or more and 4.0 μm or less. The upper layer provides durability.

[0093] It is preferable that both the lower layer and the upper layer are formed in accordance with the manufacturing method of the AlTiCN layer described later, to eliminate variations among cutting edges.

[0094] 2-3. Unintended Layers Furthermore, due to fluctuations in gas pressure and temperature in the deposition apparatus when switching deposition gases, unintended layers other than the AlTiCN layer, lower layer, and upper layer may be deposited.

[0095] 3. Substrate: (1) Material Any conventionally known substrate of this type can be used as the substrate, as long as it does not impede the achievement of the above-mentioned object. Examples include WC-based cemented carbide (WC containing Co and further containing carbonitrides of Ti, Ta, Nb, etc.), cermet (mainly composed of TiC, TiN, TiCN, etc.), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide), and cBN sintered body.

[0096] (2) Shape The shape of the substrate is not particularly limited as long as it is a shape that can be used as a cutting tool, and examples thereof include the shape of an insert and the shape of a drill.

[0097] 4. Manufacturing Method The AlTiCN layer according to this embodiment can be manufactured using, for example, the following film formation gases and film formation apparatus.

[0098] (1) Composition of Film-Deposition Gas, etc. Examples of the composition of the reaction gas are as follows. Note that the gas composition is the sum of the compositions of Gas Group A and Gas Group B, which is taken as 100% by volume, and will be abbreviated as % below. Gas Group A: Gas composition TiCl ４ :0.07~0.40%, AlCl ３:0.20~1.29%, N ２ :0.0~10.0%, C ２ H ４ :0.0~0.5%, H ２ : Remaining Gas group B: Gas composition NH ３ :1.00~4.40%, H ２ : 25.0 to 35.0% Reaction atmosphere pressure: 4.0 to 5.0 kPa Reaction atmosphere temperature: 700 to 850°C Supply cycle: 1.00 to 5.00 seconds Gas supply time per cycle: 0.15 to 0.25 seconds Phase difference between the supply of gas group A and the supply of gas group B: 0.10 to 0.20 seconds The film formation gas composition, reaction atmosphere pressure, reaction atmosphere temperature, supply cycle, gas supply time per cycle, and phase difference between the supply of gas group A and the supply of gas group B are set values.

[0099] (2) Film-forming device An example of a film-forming device is a film-forming device equipped with a gas ejection pipe (7) as shown in Figures 3 and 4. This film-forming device is used for a coated tool having four cutting edges, and ejects film-forming gas toward the four flanks at the same time so that all parts of the cutting edges are the same distance from the tips of the gas ejection pipes (gas supply parts) of the film-forming device.

[0100] The substrate (6) is placed on a plate-like jig (not shown), and gas is ejected in four directions through the spaces between the gas ejection pipes. When forming a film on the cutting edge on the underside of the substrate, for example, a spacer can be placed between the plate-like jig and the substrate to create a gap, and the cutting edge can be positioned so that all parts of the cutting edge are the same distance from the tip of the gas supply pipe of the film-forming device.

[0101] The above description includes the following additional features: (Additional Note 1) A surface-coated cutting tool having a substrate and a coating layer provided on the substrate, (1) the coating layer includes a composite nitride layer or composite carbonitride layer of Al and Ti having crystal grains of a face-centered cubic structure of NaCl, (2) the tool has a plurality of cutting edges of the same shape, and on the flank faces of all the cutting edges, the composite nitride layer or composite carbonitride layer of Al and Ti is ｘ Ti １－ｘ ) (Cｙ N １－ｙ ) (average content of x x ａｖｇ is 0.60 or more and 0.95 or less, and the average content of y ａｖｇ (3) In each of the flanks of all the cutting edges, the crystal grains having the NaCl-type face-centered cubic structure contained in the coating layer have 200 diffraction lines measured using an X-ray diffractometer, the average value of the 200 diffraction line intensity values ​​is defined as I(200), and its standard deviation is σ I（２００） Then, σ I（２００） / I(200) satisfies 0.00 or more and 0.20 or less, (4) for each of all the cutting edges, the thickness Lm of the coating layer on a line 100 μm away from the ridge of the cutting edge in the flank direction, and the average value of Lm for all the cutting edges ａｖｇ , standard deviation is σ Ｌ Then, σ Ｌ / L ａｖｇ (5) on each flank face of all the cutting edges, the Al and Ti composite nitride layer or composite carbonitride layer contains columnar crystals, and the maximum value x of X in the columnar crystals ｍａｘ * is the average value of x ｍａｘ and the minimum value x of X ｍｉｎ * is the average value of x ｍｉｎ is 0.02≦x ｍａｘ -x ｍｉｎ TC(200) is an average value of the orientation index TC of the crystal grains having the NaCl type face-centered cubic structure contained in the coating layer on each of the flank faces of all the cutting edges. ａｖｇ The surface-coated cutting tool according to claim 1, characterized in that the TC(200) of the crystal grains having the NaCl-type face-centered cubic structure contained in the coating layer is 1.0 or more and 6.0 or less. ａｖｇ (200), and its standard deviation is σ ＴＣ（２００） Then, σ ＴＣ（２００） / TC ａｖｇ(200) satisfies 0.00 or more and 0.10 or less. (Appendix 4) The surface-coated cutting tool according to any of Appendices 1 to 3, characterized in that, on each of the flank faces of all of the cutting edges, a region in which the Al and Ti contents contained in the coating layer change is present in 70 area% or more of a longitudinal section of the coating layer. (Appendix 5) The surface-coated cutting tool according to any of Appendices 1 to 4, characterized in that, on each of the flank faces of all of the cutting edges, the average grain width W of columnar crystals in the Al and Ti composite nitride layer or composite carbonitride layer contained in the coating layer is 0.10 μm or more and 1.20 μm or less, and the average aspect ratio A of the columnar crystals is 2.0 or more and 10.0 or less. (Appendix 6) The surface-coated cutting tool according to any one of Appendices 1 to 5, wherein the Al and Ti composite nitride layer or composite carbonitride layer contains chlorine at a content of 0.005 atomic % or more and 0.500 atomic % or less. (Appendix 7) The surface-coated cutting tool according to any one of Appendices 1 to 6, wherein the region where the Al and Ti contents vary is distributed in a mesh-like, layered or granular manner. (Appendix 8) The surface-coated cutting tool according to any one of Appendices 1 to 7, wherein a lower layer is disposed between the Al and Ti composite nitride layer or composite carbonitride layer and the substrate. (Appendix 9) The surface-coated cutting tool according to any one of Appendices 1 to 8, wherein an upper layer is disposed on top of the Al and Ti composite nitride layer or composite carbonitride layer.

[0102] Next, an example will be described. Here, as an example of the coated tool of the present invention, an example in which the coated tool is applied to an insert cutting tool using a WC-based cemented carbide as the substrate material will be described, but the same applies when other substrate materials are used, and when the coated tool is applied to drills and end mills in the shape of the substrate.

[0103] As raw material powders, WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr ３ C ２ These raw material powders were blended to the composition shown in Table 1.

[0104] Wax was further added, and the mixture was mixed in a ball mill in acetone for 24 hours. After drying under reduced pressure, the mixture was pressed into a green compact of a predetermined shape at a pressure of 98 MPa. This green compact was then vacuum sintered by holding it at a temperature of 1420°C in a vacuum of 5 Pa for 1 hour. After sintering, WC-based cemented carbide substrates A to C having an insert shape (four cutting edges) of SEMT13T3AGSN manufactured by Mitsubishi Materials Corporation, and WC-based cemented carbide substrates D to F having an insert shape (four cutting edges) of ISO standard CNMG120412 were produced, respectively.

[0105] Next, an AlTiCN layer was formed on the surface of each of these substrates A to F by CVD under the deposition conditions shown in Table 2 using a deposition apparatus whose gas ejection tube arrangement is shown in Figures 3 and 4, to obtain Examples 1 to 27 shown in Tables 7 and 8. The average thickness Lm of the coating layer on a line 100 μm away from the ridge of the cutting edge in the flank direction was determined by measuring the thickness of the coating layer at four points selected from the multiple points spaced apart by the aforementioned predetermined distance, each 30 μm apart, and calculating the average value Lm. Lm was determined for all cutting edges, and then averaged to obtain Lavg.

[0106] In addition, some of Examples 1 to 27 have a lower layer or a lower layer and an upper layer as shown in Table 4, and these layers were formed under the film formation conditions shown in Table 3.

[0107] For comparison, an AlTiCN layer was formed on the surface of each of the substrates A to F by CVD using a film formation apparatus (FIGS. 5 and 6) considered to be equivalent to the example described in Patent Document 1, which is cited as a prior art document, under the formation symbols a to j showing the film formation conditions shown in Table 5, to obtain Comparative Examples 1 to 15 shown in Tables 7 and 8.

[0108] Here, Comparative Examples 1 to 15 have a lower layer or a lower layer and an upper layer as shown in Table 6, and these layers were formed under the film-forming conditions shown in Table 3.

[0109] The film formation apparatus shown in Figure 5 had a bell-shaped reaction vessel (11) with a diameter of 250 mm and a height of 750 mm. The external heater (12) was a heater capable of heating the inside of the reaction vessel (11) from 700°C to 1050°C. A ring-shaped jig (13) with an outer diameter of 220 mm and a central hole with a diameter of 65 mm formed in the center was used as the tray. The substrates were placed on the outer periphery of the jig, and substrates A to F were placed at intervals of 20 mm along the radial direction of the jig (13), and were placed at approximately equal intervals along the circumferential direction of the jig (13).

[0110] The gas supply pipe (14) used had the configuration shown in Figure 6, and during film formation, it was rotated around the rotation axis (16) shown in Figures 5 and 6. As shown in Table 5, the gas supply pipe (14) had gas outlets that were adjacent to each other in the circumferential direction, and each of the gas group A outlet and the gas group B outlet had one hole (ejection hole (18)) or two holes (ejection hole (19) and ejection hole (20)), as shown in Figure 6. When there were two holes (ejection hole (19) and ejection hole (20)) in the same gas group flow section, their relative positions were determined by the angle α between them, as shown in Figure 6.

[0111] Furthermore, one set of gas group A outlets and gas group B outlets, which are positioned adjacent to each other in the circumferential direction, was provided for the space (15) between the trays on which the substrates in FIG. 5 were placed, and the flow rates of gases from gas group A and gas group B ejected per tray were the flow rates of the gases listed in Table 5.

[0112] Chemical vapor deposition apparatuses generally used in the manufacture of surface-coated cutting tools have a configuration in which the gas supply pipe is installed at the center of the reaction vessel, as shown in Figures 5 and 6. To convert this apparatus to the configuration shown in Figures 3 and 4 as in this embodiment, significant design changes are required with regard to the branching of the gas supply pipe and the jig for placing the substrate. Figures 3 and 4 illustrate a film formation configuration for one substrate, but by stacking jigs of this configuration in the vertical direction, it is possible to form coating layers on multiple tools.

[0113] Tables 7, 8, 9, and 10 show the compositions, area ratios of the NaCl-type face-centered cubic structure, average thickness of the flank, changes in the Al and Ti contents, orientation index of the flank, average grain size, and aspect ratio of Examples 1 to 27 and Comparative Examples 1 to 15. The measured values ​​k for each cutting edge are numbered 1 to 4.

[0114]

[0115]

[0116]

[0117]

[0118] In Table 4, "-" indicates that the corresponding layer does not exist.

[0119]

[0120] In Table 5, "jet nozzle angle" refers to α in FIG. 6, and "-" indicates that no angle is formed because there is only one jet nozzle.

[0121]

[0122] In Table 6, "-" indicates that the corresponding layer does not exist.

[0123]

[0124] In Table 7, in the column "Are 70% or more by area of ​​crystal grains with a face-centered cubic structure of NaCl present in all cutting edges?", "○" indicates that it is true, and "×" indicates that the crystal grains with a face-centered cubic structure of NaCl present in one or more cutting edges are 50% or more by area and less than 70% by area. In other columns, "○" indicates that the matter described in the column is true, and "×" indicates that it is not true.

[0125]

[0126] In Table 8, for "Are all cutting edges 70% or more by area?", "○" indicates that it is true, "×" indicates that one or more cutting edges are 50% or more by area but less than 70% by area, and "-" indicates that it could not be measured. Also, in the column "Is it present on all cutting edges?", "○" indicates that it is true, "×" indicates that it is not true, and "-" indicates that it could not be measured.

[0127]

[0128] In Table 9, "existence in a mesh, layer, or granular form" refers to "the average value (x ａｖｇ *) (high Al content regions) with a difference of +1% or more and regions (low Al content regions) with a difference of -1% or more are distributed in a mesh, layer, or granular pattern, with "○" indicating that they are distributed and "-" indicating that they are not distributed, and "minimum value of the distance between the outer edges of each region" refers to "the minimum value of the distance between the outer edges of high Al content regions separated by low Al content regions, or the minimum value of the distance between the outer edges of low Al content regions separated by high Al content regions." Also, in the column "Is the ratio between 0.02 and 0.40 for all cutting edges?", "○" indicates that it is applicable, "x" indicates that it is not applicable, and "-" in other columns indicates that it could not be measured.

[0129]

[0130] In Table 10, TCi (where i = 1 to 4) under the column of TC(200) is TCi(200), and σTC is σ ＴＣ（２００） In addition, "○" indicates that the item is applicable, "×" indicates that the item is not applicable, and "-" indicates that the item could not be measured.

[0131] Next, for Examples 1 to 9 and Comparative Examples 1 to 5, the various base materials A to C (SEMT13T3AGSN shape) were all subjected to single-blade cutting in which only one blade was clamped to the tip of an alloy steel cutter with a cutter diameter of 80 mm using a fixing jig, and cutting test 1, which is a dry high-speed face milling and center-cut cutting process of carbon steel, was carried out as described below.

[0132] The flank wear width of the cutting edge was measured for all four cutting edges of each tool substrate every minute of cutting, and the cutting time until the flank wear width reached 0.2 mm or more, which is the lifespan criterion, was determined as the time until the tool life was reached. The average and standard deviation were then calculated. Table 11 shows the results of Cutting Test 1.

[0133] Cutting test 1: Dry high-speed face milling, center cut cutting Cutter diameter: 80 mm, single-blade cutting Workpiece: JIS S45C block material, width 60 mm, length 200 mm Rotation speed: 1393 / min Cutting speed: 350 m / min Depth of cut: 2.0 mm Feed per blade: 0.2 mm / blade (normal cutting speed is 200 m / min)

[0134]

[0135] In Table 11, the cutting time (minutes) until the tool life is reached indicates the time (minutes) until the tool life is reached due to chipping before the flank wear width is reached.

[0136] Furthermore, for Examples 10 to 18 and Comparative Examples 6 to 10, the various coated substrates D to F (shape according to ISO standard CNMG120412) were all screwed to the tip of an alloy steel bit with a fixing jig, and cutting test 2, which is dry high-speed intermittent cutting of ductile cast iron, was carried out as described below.

[0137] The flank wear width of the cutting edge was measured for all four cutting edges on the top and bottom acute-angle corners of each tool base every 0.5 minutes of cutting, and the cutting time until the flank wear width reached 0.3 mm or more, which is the lifespan criterion, was determined as the time until the tool life was reached. The average and standard deviation were calculated. Table 12 shows the results of Cutting Test 2.

[0138] Cutting test 2: Dry high-speed intermittent cutting Workpiece: JIS FCD700 round bar with four longitudinally equally spaced grooves Cutting speed: 400 m / min Depth of cut: 1.0 mm Feed: 0.2 mm / rev (Normal cutting speed is 150 to 200 m / min)

[0139]

[0140] In Table 12, the cutting time (minutes) until the tool life is reached indicates the time (minutes) until the tool life is reached due to chipping before the flank wear width is reached.

[0141] Furthermore, for Examples 19 to 27 and Comparative Examples 11 to 15, the various base materials A to C (SEMT13T3AGSN shape) were all subjected to single-blade cutting in which only one blade was clamped to the tip of an alloy steel cutter having a cutter diameter of 80 mm using a fixing jig, and cutting test 3, which is a dry high-speed face milling and center-cut cutting process of alloy steel, was carried out as described below.

[0142] For all four cutting edges of each tool substrate, the flank wear width of the cutting edge was measured every 0.5 minutes of cutting, and the cutting time until the flank wear width reached 0.2 mm or more, which is the life judgment criterion, was measured as the time until the end of life. The average and standard deviation were then calculated. Table 13 shows the results of Cutting Test 3.

[0143] Cutting test 3: Dry high-speed face milling, center cut cutting Cutter diameter: 80 mm, single-blade cutting Workpiece: JIS SCM440 block material, width 60 mm, length 200 mm Rotation speed: 1592 / min Cutting speed: 400 m / min Depth of cut: 2.0 mm Feed per blade: 0.2 mm / blade (normal cutting speed is 200 m / min)

[0144]

[0145] In Table 13, the cutting time (minutes) until the tool life is reached indicates the time (minutes) until the tool life is reached due to chipping before the flank wear width is reached.

[0146] From the results shown in Tables 11, 12, and 13, it can be seen that in all of Examples 1 to 27, the AlTiCN layer had a uniform thickness and structure at each cutting edge, and all cutting edges had excellent resistance to thermal cracking and chipping. Therefore, even when used in high-speed intermittent cutting of carbon steel, cast iron, and alloy steel, no thermal cracking or chipping occurred at any cutting edge, and excellent wear resistance was demonstrated over a long period of time.

[0147] In contrast, from the results shown in Tables 11, 12, and 13, in all of Comparative Examples 1 to 15, the thickness and structure of the AlTiCN layer are non-uniform between cutting edges, and as a result, the thermal crack resistance and chipping resistance are also non-uniform. Therefore, when used in high-speed intermittent cutting of carbon steel, cast iron, or alloy steel, some cutting edges will have a short service life among the four cutting edges of each tool, and the average time to reach the service life will be short, while the variation (standard deviation / average) of the time to reach the service life will be large.

[0148] Therefore, it can be said that all of the Examples have a longer average service life than all of the Comparative Examples, and exhibit uniform and excellent cutting performance with less variation.

[0149] The above-disclosed embodiments are merely illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, not by the above-disclosed embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

[0150] DESCRIPTION OF SYMBOLS 1 cutting face 2 relief face 3 cutting edge ridge of main cutting edge 4 cutting edge ridge of minor cutting edge 5 corner of cutting edge 6 base body 7 gas ejection pipe 8 gas group A 9 gas group B 11 reaction vessel 12 external heating heater 13 jig 14 gas supply pipe 15 space between trays 16 rotation shaft 17 gas group A and gas group B 18-20 ejection holes

Claims

1. A surface-coated cutting tool having a substrate and a coating layer provided on the substrate, (a) the coating layer includes a composite nitride layer or composite carbonitride layer of Al and Ti having crystal grains of a face-centered cubic structure of NaCl, (b) the tool has a plurality of cutting edges of the same shape, and on the flank faces of all the cutting edges, the composite nitride layer or composite carbonitride layer of Al and Ti is (Al ｘ Ti １－ｘ ) (C ｙ N １－ｙ ) (average content of x x ａｖｇ is 0.60 or more and 0.95 or less, and the average content of y ａｖｇ (c) on each flank face of all the cutting edges, the crystal grains having the NaCl type face-centered cubic structure contained in the coating layer have 200 diffraction lines measured using an X-ray diffractometer, the average value of the 200 diffraction line intensity values ​​is defined as I(200), and its standard deviation is σ I（２００） Then, σ I（２００） / I(200) satisfies 0.00 or more and 0.20 or less, (d) for each of all the cutting edges, the thickness Lm of the coating layer on a line 100 μm away from the ridge of the cutting edge in the flank direction, and the average value of Lm for all the cutting edges ａｖｇ , standard deviation is σ Ｌ Then, σ Ｌ / L ａｖｇ (e) on each flank face of all the cutting edges, the Al and Ti composite nitride layer or composite carbonitride layer contains columnar crystals, and the maximum value x of X in the columnar crystals is ｍａｘ * is the average value of x ｍａｘ and the minimum value x of X ｍｉｎ * is the average value of x ｍｉｎ is 0.02≦x ｍａｘ -x ｍｉｎ 1. A surface-coated cutting tool, characterized in that it has a region satisfying ≦0.

40.

2. On each of the flank faces of all the cutting edges, TC (200) is the average value of the orientation index TC of the crystal grains having the NaCl type face-centered cubic structure contained in the coating layer. ａｖｇ 2. The surface-coated cutting tool according to claim 1, wherein (200) satisfies a range of 1.0 to 6.

0.

3. On each of the flank faces of all the cutting edges, the average value of the orientation index TC(200) of the crystal grains having the NaCl type face-centered cubic structure contained in the coating layer is calculated as TC ａｖｇ (200), and its standard deviation is σ ＴＣ（２００） Then, σ ＴＣ（２００） / TC ａｖｇ 3. The surface-coated cutting tool according to claim 1, wherein (200) satisfies a range of 0.00 to 0.

10.

4. A surface-coated cutting tool as described in claim 1, characterized in that on each of the flank faces of all the cutting edges, the area in which the Al and Ti contents contained in the coating layer change is present in 70% or more of the area of ​​the longitudinal cross section of the coating layer.

5. A surface-coated cutting tool as described in claim 1, characterized in that, on each of the flank faces of all of the cutting edges, the average grain width W of the columnar crystals of the Al and Ti composite nitride layer or composite carbonitride layer contained in the coating layer is 0.10 μm or more and 1.20 μm or less, and the average aspect ratio A of the columnar crystals is 2.0 or more and 10.0 or less.

6. A surface-coated cutting tool according to claim 1, characterized in that the Al and Ti composite nitride layer or composite carbonitride layer contains chlorine, the chlorine content of which is 0.005 atomic % or more and 0.500 atomic % or less.

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