Surface coated cutting tools

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

[Technical Field]

[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. All contents of said Japanese Patent Application are incorporated herein by reference. [Background technology]

[0002] As cutting tools, coated tools are known in which a coating layer is formed on the surface of a substrate such as a tungsten carbide (hereinafter referred to as WC)-based cemented carbide. Furthermore, in order to ensure that the multiple cutting edges of the coated tool have uniform cutting performance, 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 multiple substrates placed on a jig. It states that by forming a film using this apparatus, a coated tool can be obtained in which the difference in the average content of Al or Ti in the coating layer formed on the substrate on the inner circumference side of the jig and the substrate on the outer circumference side of the jig is small, and the coating layer has a uniform composition. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-20111 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention has been made in view of the above circumstances and proposals, and aims to provide a coated tool in which the degree of uniformity of the coating layer is defined, and in which all of the multiple cutting edges of the same shape have a sufficient and uniform service life even in high-speed intermittent cutting operations. [Means for solving the problem]

[0006] The 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 a composite carbonitride layer of Al and Ti having crystal grains with a face-centered cubic structure of the NaCl type, (b) The tool has a plurality of cutting edge tips having the same shape, and on the flank face of all the cutting edge tips, the composite nitride layer or the composite carbonitride layer of Al and Ti is (Al x Ti 1-x )(C y N 1-y )(where the average content x avg is 0.60 or more and 0.95 or less, and the average content y avg is 0.0000 or more and 0.0050 or less), (c) On each of the flank faces of all the cutting edge tips, the crystal grains having the face-centered cubic structure of the NaCl type contained in the coating layer, measured using an X-ray diffractometer, have 200 diffraction lines, and when the average value of the 200 diffraction line intensity values is I avg (200) and the standard deviation is σ I(200) , then σ I(200) / I avg (200) satisfies 0.00 or more and 0.20 or less, (d) On each of all the cutting edge tips, the thickness Lm of the coating layer on the line 100 μm away from the cutting edge ridge line portion in the flank face direction, when the average value of Lm for all the cutting edge tips is L avg , and the standard deviation is σ L , then σ L / L avg satisfies 0.00 or more and 0.20 or less, (e) On each of the flank faces of all the cutting edge tips, the composite nitride layer or the composite carbonitride layer of Al and Ti includes columnar crystals, and in the columnar crystals, x max *, which is the average value of the maximum value x max of X, and x min *, which is the average value of the minimum value x min of X, satisfy 0.02 ≤ x max -x minIt has a region that satisfies ≤ 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) The average value of the orientation index TC(200) of the NaCl-type face-centered cubic crystal grains contained in the coating layer at each of the relief faces of the cutting edge, is TC avg (200) must satisfy the condition of being between 1.0 and 6.0.

[0009] (2) For each of the cutting edges, the average value of the orientation index TC(200) of the NaCl-type face-centered cubic crystal grains contained in the coating layer is set to TC avg (200) The standard deviation is σ TC(200) In that case, σ TC(200) / TC avg (200) must be between 0.00 and 0.10.

[0010] (3) In each of the relief surfaces of the cutting edge, there is a region in the longitudinal cross-section of the coating layer in which the content of Al and Ti in the coating layer changes, which accounts for 70 area or more.

[0011] (4) In each of the coating layers of the cutting edge, the average particle width W of the columnar crystals in the composite nitride layer or composite carbonitride layer of Al and Ti 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, average The content ratio must be between 0.005 atomic percent and 0.500 atomic percent. 。 [Effects of the Invention]

[0013] The aforementioned surface-coated cutting tool exhibits excellent uniformity of the coating layer, and all of its cutting edges demonstrate superior heat crack resistance and chipping resistance even during high-speed intermittent cutting of alloy steel, carbon steel, and cast iron. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic cross-sectional view illustrating an example of the cutting edge ridge portion of the cutting edge of an insert. [Figure 2] This diagram schematically illustrates an example of the corner portion of the cutting edge of an insert. [Figure 3] This is a schematic diagram showing an example of the arrangement of gas supply pipes in a chemical vapor deposition apparatus for manufacturing surface-coated cutting tools according to this embodiment. [Figure 4] This is a schematic diagram showing a side view of the device described in Figure 3. [Figure 5] This is a schematic diagram of the chemical vapor deposition apparatus used to manufacture the surface-coated cutting tool in the comparative example. [Figure 6] This is a schematic diagram of the cross-section of the gas supply pipe of the apparatus shown in Figure 5. [Modes for carrying out the invention]

[0015] When coated tools are used in high-speed intermittent cutting, if the coating layer is non-uniform—that is, if the thickness, composition, etc., of the coating layer is non-uniform—the non-uniform areas become fracture initiation points, leading to thermal cracks and chipping. In particular, when a single coated tool has multiple cutting edges, if the coating layer for each cutting edge is not uniform, the cutting performance of the cutting edges will vary, resulting in differences in durability.

[0016] The inventors investigated the variations in cutting performance and durability of each cutting edge. As a result, in a coating layer having a composite nitride or composite carbonitride of Al and Ti (hereinafter, this composite nitride and composite carbonitride may be collectively referred to as AlTiCN), when crystal grains with {111} plane preferential orientation and crystal grains with {100} plane preferential orientation are mixed, or, When hexagonal crystal grains are present at grain boundaries, etc., and there are crystal grains with a {100} plane preferential orientation, the growth rate of the crystal grains differs depending on the orientation and crystal system. Therefore, when a single coated tool has multiple cutting edges, We found that the uniformity of the coating layer's thickness, orientation, and crystallinity decreases with each cutting edge, leading to variations in cutting performance and differences in durability.

[0017] On the other hand, the inventors investigated film formation using the deposition apparatus described in Patent Document 1. As a result, they found that even when using this deposition apparatus, it is not possible to sufficiently equalize the thickness, orientation, and crystallinity of the coating layers on the multiple flank surfaces of a coated tool having multiple cutting edges containing coating layers with different crystal grain growth rates. In other words, when this coated tool is used for high-speed intermittent cutting of carbon steel, cast iron, or alloy steel, it is not possible to suppress the occurrence of cutting edges with shorter service lives compared to other cutting edges, and uniform durability may not be obtained.

[0018] Based on this understanding, the inventors considered that in order for coated tools having multiple cutting edges with coating layers containing crystal grains with different growth rates to obtain uniform thermal crack resistance and chipping resistance in high-speed intermittent cutting of carbon steel, cast iron, and alloy steel, it is essential to define the permissible limits (the degree of permissible non-uniformity) for the thickness, orientation, and crystallinity of the coating layer on the flank surface. Therefore, they diligently investigated the permissible limits for the thickness and orientation uniformity of the coating layer on the flank surface of multiple cutting edges and obtained knowledge regarding these permissible limits. Furthermore, they also obtained knowledge regarding the physical properties required of the coating layer when coated tools having multiple cutting edges containing coating layers with different crystal grain growth rates are used for high-speed intermittent cutting of carbon steel, cast iron, and alloy steel.

[0019] The embodiments of the present invention will be described in detail below.

[0020] In this specification and the claims, when a numerical range is expressed as "L~M" (where L and M are both numerical values), it is synonymous with "greater than or equal to L and less than or equal to M," and the range includes an upper limit (M) and a lower limit (L). When a unit is specified only for the upper limit (M), the units of the upper limit (M) and the lower limit (L) are the same.

[0021] First, we will define the terms related to the covering tool of this embodiment.

[0022] In this specification, high-speed intermittent cutting refers to cutting at a speed higher than that typically performed by those skilled in the art, in which the cutting edge of the cutting tool repeatedly cuts and rotates.

[0023] In this specification and in the claims, a longitudinal section refers to a section perpendicular to the surface of the substrate when minute irregularities on the substrate surface are ignored and the substrate is treated as a flat surface in the case of an insert. Furthermore, in this specification, the surface of the substrate is defined as the average line (straight line) of the interface roughness between the substrate and the coating layer in the observed image of the longitudinal section. The direction perpendicular to this average line is defined as the direction perpendicular to the substrate (the thickness direction of the coating layer). Even if the substrate has a curved surface like 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 this specification and in the claims, the cutting edge refers to the portion that comes into contact with the workpiece when actually used for cutting.

[0025] 1.Coating layer The coating layer of this embodiment is A l It has a TiCN layer. This layer will be described in detail below.

[0026] (1) Crystal grains with a face-centered cubic structure of the NaCl type When a single coated tool contains multiple cutting edges of the same shape, it is preferable that the AlTiCN layer contained in the coating layer contains crystal grains with a NaCl-type face-centered cubic structure on the flank surface of all of the cutting edges. Furthermore, for all of the multiple cutting edges, the area percentage of crystal grains having a NaCl-type face-centered cubic structure in the longitudinal cross-section of the coating layer on the flank surface is preferably 50 area % or more, and more preferably 70 area % or more. This is because, while the aforementioned problems can be solved if this area percentage is 50 area % or more, if it is less than 70 area % the hardness may be low and the wear resistance may be insufficient. Note that all of the crystal grains may have a NaCl-type face-centered cubic structure (it may be 100 area %).

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

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

[0029] The procedure for measuring the area ratio of face-centered cubic crystal grains of the NaCl type is as follows: First, the grain boundaries are identified. Specifically, the 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 at, for example, 0.5 degrees to 1.0 degrees relative to the normal direction of the polished surface is irradiated with precession. At each measurement point, the electron beam is scanned with an arbitrary beam diameter and interval, and electron diffraction patterns are continuously acquired.

[0030] Then, by analyzing each measurement point, the presence or absence of a face-centered cubic structure of the NaCl type and its crystal orientation can be determined. For example, for an observation field set to have 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 were, 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. In this case, the measured crystal orientation was determined by discretely examining the measurement surface, and the orientation distribution of the entire measurement surface was obtained by representing the region up to the midpoint between adjacent measurement points with the measurement result. A square shape can be used as an example of a region represented by a measurement point (hereinafter sometimes referred to as a pixel).

[0032] If there is a difference of 5 degrees or more in crystal orientation between adjacent pixels, or if only one of the adjacent pixels exhibits a face-centered cubic structure of the NaCl type, the edges of the region where these pixels meet are defined as grain boundaries. The region enclosed by these grain boundaries is then defined as a single crystal grain.

[0033] However, pixels that exist alone and have an orientation difference of 5 degrees or more from all adjacent pixels, or where there are no adjacent measurement points with a face-centered cubic structure of the NaCl type, are not treated as crystal grains. Only pixels that are connected in groups of two or more are treated as crystal grains. In this way, grain boundary determination is performed to identify the crystal grains.

[0034] The area ratio of these NaCl-type face-centered cubic crystal grains is calculated as the ratio of the total area of ​​the identified NaCl-type face-centered cubic crystal grains to the total area of ​​the observation field. Similar measurements are performed in 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 NaCl-type face-centered cubic crystal grains constituting the AlTiCN layer.

[0035] (2) Composition of the AlTiCN layer In each of the relief surfaces of the cutting edge, the AlTiCN layer is (Al x Ti 1-x )(C y N 1-y ), (average content of x) avg The average content of y is 0.60 or higher and 0.95 or lower. avg It is preferable that the value is 0.0000 or greater and 0.0050 or less.

[0036] x avg The reason for setting this range is x avg When x falls below 0.60, the thermal crack resistance decreases, which is undesirable, while x avg This is because a value exceeding 0.95 is undesirable because it reduces wear resistance. Also, y avg The reason for setting this range is that within this range, lubrication is improved, the impact during cutting is mitigated, and chipping resistance is improved. And this average content x avg When the value is between 0.75 and 0.95, the aforementioned characteristics can be exhibited even more effectively.

[0037] x related to the average content of the AlTiCN layer avg , y avg This can be determined as follows. The measurement location is preferably the observation field near the measurement position where the average value (Lm) of the AlTiCN layer thickness of the flank surface described later is determined for each cutting edge (within a radius of 50 μm from this measurement position).

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

[0039] The C content (y) is determined, for example, by measuring the C concentration in the depth direction using secondary ion mass spectrometry (SIMS) on a 70 μm × 70 μm area of ​​the polished surface of the coating layer parallel to the substrate surface near the measurement position, and calculating the average value. Then, these average values ​​are calculated by measuring at multiple locations (for example, 3 locations) on the coating layer on all cutting edges of the same shape present in a single coated tool, and averaging all of these measurement results to obtain y. avg Let's assume that.

[0040] Note, (Al x Ti 1-x ) and (C y N 1-y The ratio to (Al is not particularly limited, x Ti 1-x When (C) is set to 1, y N 1-y The ratio to (Al is preferably 0.8 or more and 1.2 or less. The reason is that (Al x Ti 1-x ) against (C y N 1-y This is because the aforementioned objective can be achieved more reliably if the ratio of ) is within the aforementioned range.

[0041] Furthermore, even if the AlTiCN layer contains trace amounts of unavoidable impurities such as oxygen (impurities that are included unintentionally), this does not hinder the achievement of the aforementioned objectives.

[0042] (3) Mean and standard deviation of 200 diffraction line intensities for crystal grains with a face-centered cubic structure of the NaCl type in the AlTiCN layer. At each of the flank faces of the cutting edge, the NaCl-type crystal grains having a face-centered cubic structure contained in the coating layer were measured using an X-ray diffractometer and determined to have 200 diffraction lines, and the average value of the 200 diffraction line intensity was I avg Let (200) be the standard deviation, and let σ be the standard deviation. I(200) In that case, σ I(200) / I avg (200) is preferably 0.00 or greater and 0.20 or less.

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

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

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

[0046]

number

[0047] (4) Mean and standard deviation of the thickness of the AlTiCN layer on the flank For each of the aforementioned cutting edges, the average thickness Lm of the AlTiCN layer on a line 100 μm away from the cutting edge ridge in the flank direction is determined, and the average value of this Lm is calculated. avg and standard deviation σ L In that case, σ L / L avg It is preferable that the value is between 0.00 and 0.20.

[0048] L avg It is preferable that the thickness is between 1.0 μm and 20.0 μm. The reason is that within this range, sufficient wear resistance can be ensured and excellent chipping resistance can be obtained. avg When the particle size is between 3.0 μm and 15.0 μm, the aforementioned properties can be exhibited even more favorably.

[0049] The reason is, L avg The absence of variation, that is, the standard deviation σ L Since it is preferable that σ is 0 (or not 0), L The lower limit of / Lavg is 0.00, while σ L If / Lavg is greater than 0.20, a variation in the thickness of the coating layer occurs due to differences in film deposition rates, which reduces the uniformity of thermal crack resistance and chipping resistance when subjected to high-speed intermittent cutting.

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

[0051] In this embodiment, the target is a coated tool that includes multiple cutting edges of the same shape within a single coated tool, and for all of the cutting edges, the average thickness Lm of the coating layer on a line 100 μm away from the cutting edge ridge in the flank direction, and the average value L of this Lm. avg and standard deviation σ L The following is what is being sought:

[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 any 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 Figure 2, a line segment of 500 μm is selected from the cutting edge ridge (3), and multiple points on the line segment obtained by shifting that line segment 100 μm in the direction of the flank surface are selected at predetermined distances apart from each other, and the thickness of the coating layer is measured and calculated as the average value Lm.

[0054] Here, the multiple points on the line segment that are separated by a predetermined length from each other can be, for example, four points separated by 30 μm, but it is preferable to select more measurement points, and is not limited to this. In this way, Lm is determined for each cutting edge, and the average is calculated as L avg We seek.

[0055] To measure the thickness, a sample for observation of the longitudinal section of the coating layer is prepared using a cross-section polisher (CP) or similar device, and the cross-section is observed using a scanning electron microscope (SEM).

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

[0057]

number

[0058] Furthermore, if a single coated cutting tool contains multiple cutting edges of the same shape, one with an acute corner and the other with an obtuse corner, it shall be treated as a surface-coated cutting tool of the present invention if either of them satisfies the requirements described herein and in the claims.

[0059] Furthermore, for circular inserts, when the cutting edge is located along the outer circumference of the circle, two points may be selected, for example, an arbitrary point on the circumference and a point located 180 degrees rotated from that point with the center of the circle as the starting point. Each of these points may be considered to be a cutting edge of the same shape, and the standard deviation may be calculated accordingly.

[0060] (5) Including columnar crystals, the change in Al and Ti content and the maximum value of x max and minimum value x min , and the area ratio S of the region having this change In each of the cutting edge relief faces, the AlTiCN layer contains columnar crystals and includes variations in Al and Ti content, and the maximum value x of the Al content (percentage) (x) in relation to the total amount of Ti and Al in this variation is max and minimum value x min However, 0.02 ≤ x max -x min It is preferable that the value ≤0.40 is satisfied. Note that columnar crystals refer to crystal grains in the AlTiCN layer whose aspect ratio A (definition will be described later) is 1.5 or greater.

[0061] x max -x min When the value is within this range, the heat crack resistance and chipping resistance of coated tools improve. However, if it is less than 0.02, this improvement is insufficient, and if it is greater than 0.40, A l The intragranular strain in the crystal grains constituting the TiCN layer becomes too large, reducing the thermal crack resistance and chipping resistance of the coated tool.

[0062] Furthermore, in each of the relief surfaces of the cutting edge, the region containing changes in Al and Ti content (details will be described later) is preferably 50 area 10%, and more preferably 70 area 10% in the longitudinal cross-section of the AlTiCN layer. The reason for this is that while the aforementioned problems can be solved if the region containing changes in Al and Ti content is 50 area 10% or more, if it is less than 70 area 10% the thermal crack resistance and chipping resistance of the coated tool when subjected to high-speed intermittent cutting may decrease. The region containing changes in Al and Ti content may be 100 area 100% in the longitudinal cross-section of the coating layer.

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

[0064] Using an energy-dispersive X-ray spectrometer attached to a scanning transmission electron microscope (STEM), the longitudinal cross-section of the coating layer is observed at appropriate magnifications ranging from 160,000x to 320,000x.

[0065] Then, in the longitudinal section of the coating layer, the width in the direction parallel to the substrate surface is 2 μm or more, and the entire rectangular observation field is set to include the thickness of the coating layer, and the content (x) of Al relative to the total amount of Ti and Al in the change in Al and Ti content is determined. The observation visual field is preferably in the vicinity of the measurement position for obtaining the average value (Lm) of the thickness of the AlTiCN layer on the flank face for each cutting edge tip described above (within a circle with a radius of 50 μm from this measurement position).

[0066] For each crystal grain (columnar crystal) of the face-centered cubic structure of the NaCl type and the hexagonal crystal structure included in the entire observation visual field, the distribution of the content (x) of Ti and Al in the total content of Al is obtained, and the maximum value x max * and the minimum value x min * both have a difference of ±1% or more from the average value (x avg *), then it is determined that the crystal grain contains a change in the content of Al and Ti.

[0067] That is, the region including the change in the content of Al and Ti refers to the region where the crystal grains determined to include the change in the content of Al and Ti are grouped (totaled). And the maximum value x measured for each crystal grain max *, the minimum value x min * of the respective average values are the maximum value x at a certain cutting edge tip max , the minimum value x min .

[0068] In addition, in the region including the change in the content of Al and Ti, a region (high Al content region) having a difference of +1% or more from the average value (x avg *) and a region (low Al content region) having a difference of -1% or more are more preferably distributed in a network shape, a layered shape or a granular shape. Furthermore, the minimum value of the interval between the outer edges of the high Al content regions separated by the low Al content regions, or between the outer edges of the low Al content regions separated by the high Al content regions is more preferably 1 nm or more and less than 50 nm.

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

[0070] The ratio occupied by the total area of the crystal grains determined to include the change in the content of Al and Ti in the observation visual field is defined as the area ratio of the region including the change in the content of Al and Ti in the coating layer.

[0071] (6) The average value (TC avg (200)) of the orientation index TC(200) At each of all the cutting edge tips, on the line 100 μm away from the cutting edge tip ridge line portion in the flank direction, having the face-centered cubic structure of the NaCl type grain orientation index When TC(200) is obtained, TC avg (200) preferably satisfies 1.0 or more and 6.0 or less.

[0072] The reason is that when TC avg (200) is less than 1.0, the thermal crack resistance at each cutting edge tip when subjected to high-speed interrupted cutting may decrease. The thermal crack resistance is better as TC avg (200) is larger, and it may even be the defined maximum value of 6.0. TC avg (200) has an excellent balance between thermal crack resistance and wear resistance when it is 1.0 or more and 3.4 or less, and has excellent thermal crack resistance when TC avg (200) exceeds 3.5 and is 6.0 or less.

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

[0074] The orientation index TC(200) is obtained as follows. [[ID=In other words, when a single coated tool contains multiple cutting edges, a 500 μm line segment is selected from the edge of each cutting edge, and the measurement position is set near the center of the line segment obtained by shifting that line segment 100 μm parallel in the flank direction. At this measurement position, the X-ray diffraction pattern is measured by micro-area X-ray diffraction measurement (example measurement conditions: Cu-Kα rays, output 50 kV, 22 mA, detection distance 150 mm, collimator diameter 100 μmΦ).

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

[0076] Here, the orientation index TC(200) is defined as follows: TC(200) = {I(200) / I0(200)} ×[(1 / 6)×Σ{I(hkl) / I0(hkl)}] -1 The measurement is taken for each cutting edge, and the average value is TC avg (200)

[0077] In addition, I(200): Measured X-ray diffraction peak intensity at the 200 diffraction line. I0(200): The average value of the standard X-ray diffraction peak intensity at the 200 diffraction line of the crystal plane of AlN as described in JCPDS card 00-046-1200. Σ(I(hkl) / I0(hkl)): The sum of the values ​​of ([measured X-ray diffraction peak intensity] / [average value of the standard diffraction peak intensity for AlN listed on the ICDD card]) for each diffraction line of 111, 200, 220, 311, 222, and 400. That is the case.

[0078] (8) Average particle width and average aspect ratio of columnar crystals The AlTiCN layer preferably contains columnar crystals on the relief surfaces of all cutting edges, with the average particle width W in the longitudinal cross-section of the columnar crystals being 0.1 μm or more and 2.0 μm or less, and the average aspect ratio A being 2.0 or more and 10.0 or less.

[0079] The reason is as follows: When the average particle width W is smaller than 0.1 μm, the fine-grained crystals may be prone to abnormal damage due to a decrease in resistance to plastic deformation and oxidation caused by an increase in grain boundaries. On the other hand, when the average particle width W is larger than 2.0 μm, the presence of coarsely grown particles may lead to a decrease in toughness.

[0080] Furthermore, when the average aspect ratio A of a crystal is less than 2.0, the interface is more likely to become the fracture initiation point in response to the shear stress generated on the surface of the AlTiCN layer during cutting, which can cause chipping. Also, when the average aspect ratio A exceeds 10.0, if minute chipping occurs at the cutting edge during cutting and chipping occurs in the adjacent columnar crystal structure, the resistance to the shear stress generated on the surface of the AlTiCN layer tends to decrease, causing the columnar crystal structure to fracture and damage to progress rapidly, resulting in large chips.

[0081] Next, we will explain how to calculate the average grain width W and average aspect ratio A of the crystal grains having a NaCl-type face-centered cubic structure at each cutting edge. First, the longitudinal section of the AlTiCN layer is polished using the method described above. The observation field is a rectangle set in the vicinity of 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 surface is determined for each cutting edge as described above. It is preferable that the field of view is large enough to include 20 or more crystal grains having a NaCl-type face-centered cubic structure, and is located near the measurement position where the average thickness (Lm) of the AlTiCN layer on the flank surface is determined.

[0082] As described above, grain boundary determination is performed to identify the crystal grains. Next, image analysis is performed to determine the maximum length H perpendicular to the substrate surface (the substrate surface is treated as a flat surface) at a certain cutting edge k. ik, the particle width W is the maximum length in the direction parallel to the substrate in the crystal grain ik. ik , and the area S of the crystal grain ik ik Measure the aspect ratio A of the crystal grain IK. ik is A ik =H ik / W ik It is calculated as follows.

[0083] <Average particle width W> Particle width (W1 to W) measured for 20 or more crystals within the observation field for each cutting edge k j , where 1 ≤ i ≤ jk, and jk is the number of crystal grains at each cutting edge. The area-weighted average of jk ≥ 20 is calculated using [Equation 3] to obtain the average grain width Wk at a certain cutting edge k. Note that jk may be the same for all cutting edges.

[0084]

number

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

[0086]

number

[0087] (9) Chlorine average Content percentage: The AlTiCN layer may contain chlorine (Cl), and if so, its average content is preferably 0.005 atomic% or more and 0.500 atomic% or less. Here, the average content of Cl is: (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 It is defined as follows.

[0088] The reason for setting the average chlorine content within the aforementioned range is that within this range, it is possible to reliably improve lubricity 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-micro-analyser (EPMA), the longitudinal section of the polished surface is irradiated with an electron beam, and the chlorine content is determined from the analysis results of the obtained characteristic X-rays. 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 surface of each cutting edge is determined. Multiple locations (for example, 3 locations) are observed in the coating layer on all cutting edges of the same shape present in a single coated tool, and the average chlorine content for each cutting edge is determined.

[0090] 2. Other layers

[0091] 2-1. Lower layer While the AlTiCN layer alone provides sufficient durability, a lower layer consisting of one or more Ti compound layers (such as Ti nitride, carbide, or carbonitride layers; the composition of these layers is not limited to stoichiometric compositions; any known composition may be used) with a total average thickness of 0.1 μm to 2.0 μm is adjacent to the substrate. C It may be placed between the N layer and the substrate. The lower layer improves the adhesion between the AlTiCN layer and the substrate.

[0092] 2-2. Upper layer An upper layer may be provided above the AlTiCN layer, consisting of one or more Ti compound layers and aluminum oxide layers (the composition of these layers is not limited to stoichiometric compositions; any known composition may be used), with a total average thickness of 0.1 μm to 4.0 μm. The upper layer provides durability.

[0093] It is preferable to deposit both the lower and upper layers in accordance with the manufacturing method of the AlTiCN layer described later, thereby eliminating variations between cutting edges.

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

[0095] 3.Base: (1)Material Any substrate known conventionally as a substrate of this type can be used, as long as it does not hinder the achievement of the aforementioned objectives. Examples include WC-based cemented carbide (including WC containing Co and further containing carbonitrides such as Ti, Ta, and Nb), cermets (such as those mainly composed of TiC, TiN, and TiCN), ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide), and cBN sintered bodies.

[0096] (2) Shape The shape of the base material is not particularly restricted as long as it is a shape that can be used as a cutting tool; examples 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, for example, using the following deposition gas and deposition apparatus.

[0098] (1) Composition of film-forming gas, etc. Examples of reaction gas compositions are as follows. Note that the gas composition is the sum of the compositions of gas group A and gas group B, with volume percentage set to 100%, and will be abbreviated as % below. Gas group A: Gas composition: TiCl4: 0.07-0.40%, AlCl3: 0.20-1.29% N2:0.0~10.0%, C2H4:0.0~0.5%, H2:Remaining Gas group B: Gas composition: NH3: 1.00~4.40%, H2: 25.0~35.0% Reaction atmosphere pressure: 4.0~5.0 kPa Reaction atmosphere temperature: 700~850℃ Supply cycle: 1.00~5.00 seconds Gas supply time per cycle: 0.15~0.25 seconds Phase difference between the supply of gas group A and the supply of gas group B: 0.10~0.20 seconds The film deposition gas composition, reaction atmosphere pressure, reaction atmosphere temperature, supply cycle, gas supply time per cycle, and the phase difference between the supply of gas group A and the supply of gas group B are set values.

[0099] (2) Film deposition equipment As an example of a film deposition apparatus, one can be described as one that has a gas ejection tube (7) arranged as shown in Figures 3 and 4. This film deposition apparatus is for a coating tool with four cutting edges, and the film deposition gas is injected at the same timing toward the four relief surfaces so that the distance from the tip (gas supply section) of the gas ejection tube of the film deposition apparatus is the same for all parts of the cutting edges.

[0100] Furthermore, the substrate (6) is placed on a plate-shaped jig (not shown), and the gas is ejected in four directions through the space between the gas ejection pipes. When depositing a film on the cutting edge on the lower surface of the substrate, for example, a spacer can be placed between the plate-shaped jig and the substrate to create a gap, and the cutting edge can be positioned so that all parts are at the same distance from the tip of the gas supply pipe of the film deposition apparatus.

[0101] The above description includes the following features. (Note 1) A surface-coated cutting tool having a substrate and a coating layer provided on the substrate, (1) The coating layer includes an Al and Ti composite nitride layer or a composite carbonitride layer having NaCl-type face-centered cubic crystal grains, (2) The tool has multiple cutting edges of the same shape, and on the relief surface of all of the cutting edges, the Al and Ti composite nitride layer or composite carbonitride layer is (Al x Ti1-x )(C y N 1-y )(average content of x) avg The average content of y is 0.60 or higher and 0.95 or lower. avg (is between 0.0000 and 0.0050), (3) On each of the relief faces of the cutting edge, the crystal grains having a face-centered cubic structure of the NaCl type 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 is I avg Let (200) be the standard deviation, and let σ be the standard deviation. I(200) In that case, σ I(200) / I avg (200) satisfies the conditions of being 0.00 or greater and 0.20 or less, (4) For each of the cutting edges, the thickness Lm of the coating layer on a line 100 μm away from the cutting edge ridge in the direction of the flank surface, and the average value of Lm for all the cutting edges, avg , the standard deviation is σ L In that case, σ L / L avg The value satisfies 0.00 or greater and 0.20 or less. (5) In each of the relief faces of the cutting edge, the Al and Ti composite nitride layer or composite carbonitride layer contains columnar crystals, and the maximum value of X in the columnar crystals x 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 Having a region that satisfies ≤0.40, A surface-coated cutting tool characterized by the following features. (Note 2) In each of the relief faces of the cutting edge, the average value of the orientation index TC(200) of the NaCl-type face-centered cubic crystal grains contained in the coating layer is TC avg A surface-coated cutting tool as described in Appendix 1, characterized in that (200) satisfies 1.0 or more and 6.0 or less. (Note 3) In each of the relief surfaces of the cutting edge, the average value of the orientation index TC(200) of the NaCl-type face-centered cubic crystal grains contained in the coating layer is set to TC avg Let (200) be the standard deviation, and let σ be the standard deviation. TC(200) In that case, σ TC(200) / TC avg A surface-coated cutting tool as described in Appendix 1 or Appendix 2, characterized in that (200) satisfies 0.00 or greater and 0.10 or less. (Note 4) A surface-coated cutting tool as described in any of the appendices 1 to 3, characterized in that, in each of the relief surfaces of the cutting edge, there is a region in the longitudinal cross-section of the coating layer where the content of Al and Ti in the coating layer changes, with an area of ​​70% or more. (Note 5) A surface-coated cutting tool as described in any of the appendices 1 to 4, characterized in that, in each of the relief faces of all the cutting edges, the average particle width W of the columnar crystals in the composite Al and Ti 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 is 2.0 or more and 10.0 or less. (Note 6) The Al and Ti composite nitride layer or composite carbonitride layer contains chlorine, average A surface-coated cutting tool as described in any of Appendix 1 to 5, characterized in that the content ratio is 0.005 atomic% or more and 0.500 atomic% or less. (Note 7) A surface-coated cutting tool as described in any of Appendix 1 to 6, characterized in that regions with varying Al and Ti content are distributed in a network, layered, or granular manner. (Note 8) A surface-coated cutting tool according to any one of the appendices 1 to 7, characterized in that it has a lower layer between the Al and Ti composite nitride layer or composite carbonitride layer and the substrate. (Note 9) A surface-coated cutting tool according to any one of the appendices 1 to 8, characterized in that it has an upper layer on top of the Al and Ti composite nitride layer or composite carbonitride layer. [Examples]

[0102] Next, we will describe some examples. Here, as an example of the coated tool of the present invention, we describe its application to an insert cutting tool using a WC-based cemented carbide as the base material. However, the same applies when other materials are used as the base material, and the same applies when the base shape is applied to a drill or end mill.

[0103] As raw material powders, WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, Cr3C2 powder, TiN powder, and Co powder were prepared and blended according to the formulations shown in Table 1.

[0104] Furthermore, wax was added and the mixture was ball-milled in acetone for 24 hours. After reduced-pressure drying, it was press-molded into a compact of a predetermined shape at a pressure of 98 MPa. This compact was then vacuum-sintered at a temperature of 1420°C for 1 hour in a vacuum of 5 Pa. After sintering, substrates A to C made of WC-based cemented carbide with the insert shape (four cutting edges) of Mitsubishi Materials Corporation's SEMT13T3AGSN, and substrates D to F made of WC-based cemented carbide with the insert shape (four cutting edges) of ISO standard CNMG120412 were manufactured.

[0105] Next, AlTiCN layers were formed on the surfaces of these substrates A to F by CVD using a deposition apparatus with the gas ejection tube arrangement shown in Figures 3 and 4, under the deposition conditions shown in Table 2, 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 cutting edge ridge in the flank direction was determined by selecting four points 30 μm apart from the predetermined distance points mentioned above, measuring the thickness of the coating layer, and taking the average value Lm. Lm was determined for all cutting edges, and Lavg was calculated by averaging them.

[0106] Examples 1 to 27 include those having 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] Furthermore, for comparison, AlTiCN layers were formed on the surfaces of these substrates A to F by CVD using a film deposition apparatus (Figures 5 and 6) considered to be equivalent to the example described in Patent Document 1, which was cited as prior art, with formation symbols a to j indicating the film deposition 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 either a lower layer or a lower layer and an upper layer, as shown in Table 6, and these layers were formed under the film formation conditions shown in Table 3.

[0109] As shown in Figure 5, the film deposition apparatus consisted of a bell-shaped reaction vessel (11) with a diameter of 250 mm and a height of 750 mm. An external heating element (12) was used, 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 of 65 mm in diameter was used as the tray. The substrates were placed on the outer circumference of the jig, and substrates A to F were placed at 20 mm intervals along the radial direction of the jig (13) and 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 described in Table 5, the gas outlets in the gas supply pipe (14) that are adjacent to each other in the circumferential direction, as shown in Figure 6, consist of either one outlet (18) or two outlets (19 and 20) for both gas group A and gas group B. When there are two outlets (19 and 20) belonging to the same gas group flow section, their relative positions were determined by the angle α shown in Figure 6.

[0111] Furthermore, one pair of gas group A and gas group B nozzles, which are adjacent to each other in the circumferential direction, were provided for the space (15) between the trays on which the base body shown in Figure 5 was placed. The gas flow rates of gas group A and gas group B supplied to each tray were as shown in Table 5.

[0112] Generally, chemical vapor deposition apparatuses used for manufacturing surface-coated cutting tools have a configuration in which the gas supply pipe is installed in the center of the reaction vessel, as shown in Figures 5 and 6. Therefore, in order to change this apparatus to the configuration illustrated in Figures 3 and 4 as in this embodiment, significant design changes are required regarding the branching of the gas supply pipe and the jigs for mounting the substrates. Figures 3 and 4 illustrate the film deposition method on a single substrate, but by stacking jigs of this configuration in the height direction, it becomes possible to deposit coating layers on multiple tools.

[0113] Tables 7, 8, 9, and 10 show the composition, area percentage of NaCl-type face-centered cubic structure, average thickness of the flank, changes in Al and Ti content, orientation index of the flank, and average particle size for Examples 1-27 and Comparative Examples 1-15. width , average Shows the aspect ratio. The measured value k for each cutting edge is distinguished by numbers 1 through 4.

[0114] [Table 1]

[0115] [Table 2]

[0116] [Table 3]

[0117] [Table 4]

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

[0119] [Table 5]

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

[0121] [Table 6]

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

[0123] [Table 7]

[0124] In Table 7, in the column "Are NaCl-type face-centered cubic crystal grains present in 70 area percentage or more at all cutting edges?", "○" indicates that the condition is met, and "×" indicates that NaCl-type face-centered cubic crystal grains are present in 50 area percentage or more but less than 70 area percentage at one or more cutting edges. In addition, in the "Other" column, "○" indicates that the item is applicable, and "×" indicates that it is not applicable.

[0125] [Table 8]

[0126] In Table 8, "○" indicates that all cutting edges have an area of ​​70% or more, "×" indicates that one or more cutting edges have an area of ​​50% or more but less than 70%, and "-" indicates that measurement was not possible. Furthermore, in the column for "Is it present at all cutting edges?", "○" indicates that it is present, "×" indicates that it is not present, and "-" indicates that it could not be measured.

[0127] [Table 9]

[0128] In Table 9, "presence in a network, layered, or granular form" means "the average value (x) in the region including changes in Al and Ti content." avg *) indicates that regions showing a difference of +1% or more compared to (high Al content regions) and regions showing a difference of -1% or more compared to (low Al content regions) are distributed in a network, layered, or granular manner. "○" indicates that they are distributed, and "-" indicates that they are not distributed. "Minimum distance between the outer edges of each region" refers to "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." Furthermore, in the column "Is the value between 0.02 and 0.40 at all cutting edges?", "○" indicates that the value is met, "×" indicates that it is not met, and "-" in other columns indicates that measurement was not possible.

[0129] [Table 10]

[0130] In Table 10, TCi (where i=1~4) below the TC(200) column is TCi(200), and σTC is σ TC(200) That is the case. Additionally, "○" indicates that the item is applicable, "×" indicates that it is not applicable, and "-" indicates that measurement was not possible.

[0131] Next, for each of the above-mentioned Examples 1 to 9 and Comparative Examples 1 to 5, a single-edge cutting test was performed in which each of the above-mentioned base bodies A to C (SEMT13T3AGSN shape) 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 shown below.

[0132] For all four cutting edges of each tool base, the wear width of the flank surface of the cutting edge was measured after every minute of cutting. The cutting time at which the flank surface wear width exceeded 0.2 mm, which is the lifespan criterion, was measured as the time until the tool reached the end of its lifespan. The mean 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 process Cutter diameter: 80mm, single-edge cutting Workpiece material: JIS S45C block material, 60mm wide, 200mm long. Rotation speed: 1393 / min Cutting speed: 350m / min Cutting depth: 2.0mm Feed rate per tooth: 0.2 mm / tooth (The usual cutting speed is 200 m / min)

[0134] [Table 11]

[0135] In Table 11, the cutting time (minutes) to reach the end of life refers to the time (minutes) to reach the end of life due to chipping occurring before the flank wear width is reached.

[0136] Furthermore, regarding Examples 10 to 18 and Comparative Examples 6 to 10, the various... base body With shapes D through F (ISO standard CNMG120412) all screwed to the tip of an alloy steel cutting tool using a fixing jig, cutting test 2, which is a dry high-speed intermittent cutting process of ductile cast iron, was performed as shown below.

[0137] For each tool base, the wear width of the flank surface of the cutting edge was measured for all four cutting edges at the sharp corners on the upper and lower surfaces. The cutting time at which the flank surface wear width exceeded 0.3 mm, which is the lifespan criterion, was measured as the time until the tool reached the end of its lifespan. The mean and standard deviation were then calculated. Table 12 shows the results of cutting test 2.

[0138] Cutting Test 2: Dry High-Speed ​​Intermittent Cutting Workpiece material: JIS FCD700 round bar with four longitudinal grooves spaced evenly along its length. Cutting speed: 400m / min Cut: 1.0mm Feed rate: 0.2mm / rev (Typical cutting speed is 150 to 200 m / min)

[0139] [Table 12]

[0140] In Table 12, the cutting time (minutes) to reach the end of life refers to the time (minutes) to reach the end of life due to chipping occurring before the flank wear width is reached.

[0141] Furthermore, for the above-mentioned Examples 19-27 and Comparative Examples 11-15, each of the above-mentioned base bodies A-C (SEMT13T3AGSN shape) was clamped to the tip of an alloy steel cutter with a cutter diameter of 80 mm using a fixing jig, and a single-edge cutting test 3 was performed, which is a dry high-speed face milling and center-cut cutting process of alloy steel, as shown below.

[0142] For all four cutting edges of each tool base, the flank wear width of the cutting edge was measured every 0.5 minutes of cutting. The cutting time at which the flank wear width exceeded 0.2 mm, which is the lifespan criterion, was measured as the time until the tool reached the end of its lifespan. The mean 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 Cutting Cutter diameter: 80mm, single-edge cutting Workpiece material: JIS SCM440 block material, 60mm wide, 200mm long. Rotation speed: 1592 / min Cutting speed: 400m / min Cutting depth: 2.0mm Feed rate per tooth: 0.2 mm / tooth (The usual cutting speed is 200 m / min)

[0144] [Table 13]

[0145] In Table 13, the cutting time (minutes) to reach the end of life refers to the time (minutes) to reach the end of life due to chipping occurring before the flank wear width is reached.

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

[0147] In contrast, the results shown in Tables 11, 12, and 13 indicate that in all of Comparative Examples 1 to 15, the thickness and structure of the AlTiCN layer are non-uniform between the cutting edges. Consequently, the thermal crack resistance and chipping resistance are also non-uniform. Therefore, when used for high-speed intermittent cutting of carbon steel, cast iron, and alloy steel, some cutting edges of each tool will have a shorter service life. This results in a shorter average time to reach the end of service life and a larger variation in the time to reach the end of service life (standard deviation / mean).

[0148] Therefore, it can be said that all of the embodiments exhibit a longer average service life and less variation compared to all of the comparative examples, as well as uniform and superior cutting performance.

[0149] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments described herein, and all modifications within the scope are intended to be in the sense of equivalents of the claims. [Explanation of Symbols]

[0150] 1 Scoop surface 2 Escape 3. The cutting edge ridge of the main cutting edge 4. Edge of the secondary cutting edge 5. Corner of the cutting edge 6 Base 7. Gas nozzle 8 Gas Group A 9 Gas Group B 11 Reaction vessel 12 External heating element 13. Jig 14 Gas supply pipe 15 Space between trays 16 Rotation axis 17. Gas Group A and Gas Group B 18~20 spout hole

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 NaCl-type face-centered cubic crystal grains, (b) The tool has a plurality of cutting edges of the same shape, and on the flank surface of all of 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) ａｖｇ The average content of y is 0.60 or higher and 0.95 or lower. ａｖｇ (is between 0.0000 and 0.0050), (c) At each of the relief faces of the cutting edge, the NaCl-type crystal grains having a face-centered cubic structure contained in the coating layer are measured using an X-ray diffractometer and have 200 diffraction lines. The average value of the 200 diffraction line intensity is Iavg(200), and its standard deviation is σ I（２００） In that case, σ I（２００） / Iavg(200) satisfies the conditions of being 0.00 or greater and 0.20 or less. (d) At each of all the cutting edge tips, the thickness Lm of the coating layer on a line 100 μm away from the cutting edge tip ridge line portion in the direction of the flank, and the average value of Lm at all the cutting edge tips is L ａｖｇ , the standard deviation is σ Ｌ When taking it as, σ Ｌ / L ａｖｇ satisfies 0.00 or more and 0.20 or less, (e) In each of the relief faces of the cutting edge, the composite nitride layer or composite carbonitride layer of Al and Ti contains columnar crystals, and the maximum value of X in the columnar crystals x ｍａｘ * is the average value of x ｍａｘ and the minimum value of X x ｍｉｎ * is the average value of x ｍｉｎ 0.02 ≤ x ｍａｘ -x ｍｉｎ Having a region that satisfies ≤ 0.40, A surface-coated cutting tool characterized by the following features.

2. In each of the relief surfaces of the cutting edge, the average value of the orientation index TC(200) of the NaCl-type face-centered cubic crystal grains contained in the coating layer is TC ａｖｇ A surface-coated cutting tool according to claim 1, characterized in that (200) satisfies 1.0 or more and 6.0 or less.

3. In each of the relief surfaces of the cutting edge, the average value of the orientation index TC(200) of the NaCl-type face-centered cubic crystal grains contained in the coating layer is set to TC ａｖｇ (200) and its standard deviation is σ ＴＣ（２００） In that case, σ ＴＣ（２００） / TC ａｖｇ A surface-coated cutting tool according to claim 1 or 2, characterized in that (200) satisfies 0.00 or more and 0.10 or less.

4. The surface-coated cutting tool according to claim 1, characterized in that, in each of the relief surfaces of the cutting edge, there is a region in the longitudinal cross-section of the coating layer in which the content of Al and Ti in the coating layer changes, with an area of ​​70% or more.

5. The surface-coated cutting tool according to claim 1, characterized in that, in each of the relief faces of all the cutting edges, the average particle width W of the columnar crystals in the composite Al and Ti 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 is 2.0 or more and 10.0 or less.

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

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