Surface coated cutting tools

Abstract

A surface-coated cutting tool which has excellent durability even when used in the high-feed cutting processing of austenitic stainless steel, wherein; an A layer, a B layer and a C layer contact one another in order from a substrate; the total of the average thicknesses of said layers is 0.7-21.0μm; the A layer has an average thickness of 0.1-2.0μm and contains a Ti nitride or carbonitride; the B layer has an average thickness of 0.1-0.5μm and contains crystal grains, at least 30% by area of which have a wurtzite-type hexagonal structure and comprise (AlXBTi1-XB) (CYBN1-YB) (0.80≤XB≤0.95, 0.00≤YB<0.05), with the remainder having an NaCl-type face-centered cubic structure; and the C layer has an average thickness of 0.5-20.0μm and contains crystal grains, 5-25% by area of which have a wurtzite-type hexagonal structure and comprise (AlXCTi1-XC) (CYCN1-YC) (0.65≤XC≤0.90, 0.00≤YC<0.05), with the remainder having an NaCl-type face-centered cubic structure.

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 based on Japanese Patent Application No. 2023-34690 filed on March 7, 2023. All the descriptions contained in the Japanese application are incorporated herein by reference.

Background Art

[0002] Conventionally, in order to extend the life of a cutting tool, there is a coated tool in which a coating layer is coated on the surface of a substrate such as a tungsten carbide (hereinafter sometimes referred to as WC)-based cemented carbide, and the wear resistance and the like of this coated tool are improved. And in order to further improve the cutting performance of the coated tool, various proposals have been made regarding the composition and structure of the coating layer.

[0003] For example, in Patent Document 1, the surface of the substrate includes two first crystal phases and a second crystal phase disposed therebetween, and the two first crystal phases each independently have a sodium chloride-type crystal structure of Ti xα , 1-x2 , x1 , yα , (1-xα) , x2 , 1-x1 Al x1 N phase and an Al x2 Ti 1-x2 N phase are alternately laminated, and the x1 satisfies 0.1 ≦ x1 ≦ 0.7, the x2 satisfies 0.7 < x2 ≦ 0.95, and the second crystal phase includes a coating layer containing AlN having a wurtzite-type crystal structure. A coated tool is described, and it is said that the coated tool has a long life in cutting high-carbon chromium bearing steel, cast iron, etc.

[0004] Also, for example, in Patent Document 2, the coating layer has a TiAlCN layer α containing crystal grains having a wurtzite-type hexagonal crystal structure at 70 area% or more Tool surface side and a TiAlCN layer β containing crystal grains having a face-centered cubic structure of the NaCl type at 70 area% or more on the substrate side, each in a single layer, and the composition of the TiAlCN layer α is (Ti (1-xα) Al xα )(C yα N(1-yα) ), 0.70 ≦ xα ≦ 0.95, 0.000 ≦ yα ≦ 0.010, and the composition of the TiAlCN layer β is (Ti (1-xβ) H Al xβ )(C yβ N (1-yβ) ), 0.65 ≦ xβ ≦ 0.95, 0.000 ≦ yβ ≦ 0.010, and when the average thicknesses of the TiAlCN layer α and the TiAlCN layer β are Lα and Lβ, respectively, a coated cutting tool is described with 0.5 μm ≦ Lα ≦ 10.0 μm, 1.0 μm ≦ Lβ ≦ 20.0 μm, and the coated tool is also said to have a long life even in high-speed interrupted cutting of cast iron.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] While the durability of coated tools is required not only for cutting high-carbon chromium bearing steel and ductile cast iron but also for high-feed cutting of difficult-to-machine materials such as austenitic stainless steel.

[0007] This invention has been made in view of the above circumstances and proposals, and for example, aims to obtain a surface-coated cutting tool having excellent durability (long life) even in high-feed cutting of austenitic stainless steel.

Means for Solving the Problems

[0008] The surface-coated cutting tool according to an embodiment of the present invention has a substrate and a coating layer on the surface of the substrate, (a) The coating layer has, in order from the surface of the substrate toward the tool surface, an A layer, a B layer, and a C layer that are in contact with each other, and the sum of the average thicknesses of these three layers is 0.7 to 21.0 μm, and (b) The A layer has an average thickness of 0.1 to 2.0 μm and is a layer containing a nitride or carbonitride of Ti, (c) The B layer has an average thickness of 0.1 to 0.5 μm and has an average composition of (Al XB Ti 1-XB )(C YB N 1-YB )(0.80 ≤ XB ≤ 0.95, 0.00 ≤ YB < 0.05), and in the longitudinal section of The aforementioned B layer it, crystal grains having a wurtzite-type hexagonal crystal structure occupy 30 area% or more, and the remainder is composed of crystal grains having a NaCl-type face-centered cubic crystal structure, (d) The C layer has an average thickness of 0.5 to 20.0 μm and has an average composition of (Al XC Ti 1-XC )(C YC N 1-YC )(0.65 ≤ XC ≤ 0.90, 0.00 ≤ YC < 0.05), and in the longitudinal section of The C layer it, crystal grains having a wurtzite-type hexagonal crystal structure occupy a ratio of 5 area% or more and 25 area% or less, and the remainder is composed of crystal grains having a NaCl-type face-centered cubic crystal structure.

[0009] Furthermore, the surface-coated cutting tool according to the embodiment may satisfy the following item (1).

[0010] (1) In the coating layer, the diffraction line intensity value Ic(111) of the 111 diffraction line, the diffraction line intensity value Ic(200) of the 200 diffraction line, and the diffraction intensity value Ih(100) of the 100 diffraction line of the crystal grains having a wurtzite-type hexagonal crystal structure of the crystal grains having a NaCl-type face-centered cubic crystal structure satisfy 0.1 ≤ Ih(100) / [Ic(111) + Ic(200)] ≤ 0.4 That is.

Advantages of the Invention

[0011] The surface-coated cutting tool according to the above embodiment has excellent durability, even in high-feed cutting operations on austenitic stainless steel, for example. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of an example of a longitudinal cross-section of a surface-coated cutting tool according to one embodiment of the present invention. [Modes for carrying out the invention]

[0013] The inventors have developed a composite of Al and Ti in the coating layer. nitrogen We have diligently investigated measures to suppress the peeling of the coating layer in coated tools having a crystalline layer or a composite carbonitride layer (hereinafter sometimes referred to as an (AlTi)CN layer), particularly in high-feed cutting operations, i.e., cutting operations where the feed rate is several times that of normal.

[0014] As a result, we found that durability is improved when the coating layer, extending from the substrate surface toward the tool surface, has, in order, layers A, B, and C in contact with each other, with layer A being a Ti nitride or carbonitride layer, layer B being an (AlTi)CN layer, and layer C being an (AlTi)CN layer, and when layers B and C each have a predetermined composition, and furthermore, when layers B and C contain a predetermined proportion of crystal grains having a wurtzite-type hexagonal crystal structure.

[0015] The following describes in detail an embodiment of the coating tool of the present invention. In this specification and in the claims, when a numerical range is expressed as "L~M" (where L and M are both numerical values), it is synonymous with "L or greater and M or less," and the range includes both an upper limit (M) and a lower limit (L). If a unit is specified only for the upper limit (M), the unit of the lower limit (L) is also the same.

[0016] First, an overview of the embodiments of the present invention will be described with reference to Figure 1.

[0017] Figure 1 schematically shows a longitudinal cross-section of a coating tool according to one embodiment of the present invention (a cross-section perpendicular to the horizontal plane of the substrate surface, assuming that there are no minute irregularities on the surface of the substrate). As is clear from Figure 1, the coating tool according to this embodiment has a substrate (1) with a layer A (2) in contact with the surface of the substrate (1), a layer B (3) in contact with the layer A (2) on the tool surface side of the layer A (2), and a layer C (4) in contact with the layer B (3) on the tool surface side of the layer B (3). In addition to the layer A (2), the layer B (3), and the layer C (4), the coating layer (6) also has a layer described later. surface It may have a layer (5). The following explains each layer in order.

[0018] 1.Coating layer The sum of the average thicknesses of the A layer (2), B layer (3), and C layer (4) of the coating layer (total average thickness) is preferably 0.7 to 21.0 μm. This is because if the sum of the average thicknesses is less than 0.7 μm, the abrasion resistance will be insufficient, while if it is thicker than 21.0 μm, peeling or chipping of the coating layer will occur due to internal defects in each layer.

[0019] 2.A layer Layer A in contact with the substrate surface includes a Ti nitride layer or carbonitride layer, body It acts as an adhesion layer, providing adhesion between layer B and layer B.

[0020] (1) Average composition Layer A average The composition is not particularly restricted as long as it is a Ti nitride or carbonitride. For example, formula: TiC Z N 1-Z (0.00 ≤ Z ≤ 0.05) is acceptable. Here, if Z is present in a quantity greater than 0.05, the hardness of layer A increases excessively, reducing its toughness, and layer A becomes... Body This can sometimes lead to peeling from the interface.

[0021] (2) Average thickness The average thickness of layer A is preferably 0.1 to 2.0 μm. The reason is that if it is thinner than 0.1 μm, it will not function as an adhesion layer adequately, while if it exceeds 2.0 μm, the thickness of the adhesion layer relative to the coating layer will be excessive. Wear resistance This is because it cannot be obtained. The average thickness of layer A is more preferably 0.5 to 1.5 μm.

[0022] 3.B layer Layer B, which is provided in contact with the surface of layer A, is an (AlTi)CN layer and has the function of suppressing the occurrence of cracks and the destruction of the coating layer when slight plastic deformation of the substrate occurs due to heat or impact during cutting.

[0023] (1) Average composition The average composition of layer B is (Al XB Ti 1-XB )(C YB N 1-YB In this case, it is preferable that 0.80 ≤ XB ≤ 0.95 and 0.00 ≤ YB < 0.05. The reason is as follows: If XB is less than 0.80, the proportion of crystal grains having a face-centered cubic structure of the NaCl type increases, resulting in excessive hardness of the (AlTi)CN layer and insufficient toughness, making it difficult to adequately suppress fracture of the coating layer. On the other hand, if it exceeds 0.95, the adhesion with the C layer decreases, making the C layer more prone to peeling. It is more preferable that XB be 0.85 ≤ XB ≤ 0.90.

[0024] The C component in (AlTi)CN may be included because it has the effect of improving the hardness of the B layer. However, if YB is 0.05 or higher, the high-temperature strength of the B layer decreases, so it is preferable that the upper limit of YB be less than 0.05.

[0025] Also, (Al XB Ti 1-XB ) and (C YB N 1-YB The ratio to (Al) is not limited to stoichiometric composition, XB Ti 1-XB If we set ) to 1, then (C YB N 1-YB) can be between 0.8 and 1.2. This means that the C layer (Al XC Ti 1-XC )(C YC N 1-YC The same applies to ).

[0026] ( 2 ) Average thickness The average thickness of layer B is preferably 0.1 to 0.5 μm. This is because if it is less than 0.1 μm, the aforementioned suppression of crack propagation cannot be sufficiently obtained, while if it exceeds 0.5 μm, the wear resistance of layer B decreases, making it easier for damage originating from layer B to occur. The average thickness of layer B is more preferably 0.1 to 0.3 μm.

[0027] ( 3 ) Wurtzite-type hexagonal crystal grains In layer B, it is preferable that the proportion of crystal grains having a wurtzite-type hexagonal structure in its longitudinal cross-section be 30 area % or more. This is because if it is less than 30 area % the hardness is high, sufficient toughness cannot be obtained, and adhesion with layer C decreases. The lower limit of this proportion is more preferably 50 area % or more.

[0028] There is no upper limit to the percentage of crystal grains having a wurtzite-type hexagonal crystal structure (it can be 100 area%), but in one example of the manufacturing method described later, the upper limit is approximately 90 area%). Furthermore, the crystal structure of grains other than those with a wurtzite-type hexagonal crystal structure is a NaCl-type face-centered cubic crystal structure.

[0029] 4.C layer The C layer, which is formed on the surface of the B layer, has wear resistance and acts as a layer that suppresses the adhesion of welds during cutting.

[0030] (1) Average composition The average composition of layer C is given by the formula: (Al XC Ti 1-XC )(C YC N 1-YC In this case, it is preferable that 0.65 ≤ XC ≤ 0.90 and 0.00 ≤ YC < 0.05. The reason is as follows: If XC is less than 0.65, the oxidation resistance inherent in (AlTi)CN cannot be sufficiently obtained. On the other hand, if it exceeds 0.90, the hardness of the C layer decreases. It is more preferable that XC be 0.70 ≤ XC ≤ 0.85.

[0031] The carbon (C) component in (AlTi)CN may be included because it improves the hardness of the carbon layer. However, if YC is 0.05 or higher, the high-temperature strength of the carbon layer decreases, so it is preferable that the upper limit of YC be less than 0.05.

[0032] (2) Average thickness The average thickness of the C layer is preferably 0.5 to 20.0 μm. The reason for this is as follows: If it is less than 0.5 μm, the abrasion resistance and suppression of welding are insufficient. On the other hand, if it exceeds 20.0 μm, cracks originating from the surface of the coating layer are more likely to cause fracture that extends throughout the entire coating layer. The average thickness of the C layer is more preferably 3.0 to 15.0 μm.

[0033] (3) Wurtzite-type hexagonal crystal grains In layer C, it is preferable that the proportion of grains having a wurtzite-type hexagonal crystal structure in its longitudinal cross-section be between 5 area% and 25 area%. This is because if the proportion of grains having a wurtzite-type hexagonal crystal structure is less than 5 area%, good adhesion with layer B cannot be obtained, leading to fracture of the coating layer at the interface with layer B. On the other hand, if it exceeds 25 area%, it becomes difficult to obtain sufficient hardness in layer C, resulting in reduced wear resistance. More preferably, the proportion of wurtzite-type hexagonal crystal grains is between 10 area% and 20 area%. Furthermore, the crystal structure of grains other than those with a wurtzite-type hexagonal crystal structure is a NaCl-type face-centered cubic crystal structure.

[0034] 5. Other layers Other layers include layers that may be intentionally formed and layers that are not intentionally formed (layers that may occur unintentionally).

[0035] (1) Layers that may be intentionally formed The following are examples of layers that may be intentionally formed into a film: surface It is possible to raise the layer. The outermost layer may be selectively provided on the tool surface side of the C layer (the outermost layer may be omitted). Most surface As a layer, for example, a TiN layer (the atomic ratio of Ti to N in the TiN layer is not limited to stoichiometric values) may be provided. When this TiN layer is provided, the TiN layer itself has a golden hue, so it can be used as an identification layer to distinguish whether a coated tool is unused or used by the change in hue. The average thickness of this TiN layer used as an identification layer can be, for example, 0.1 to 1.0 μm.

[0036] (2) Layers that are not intentionally formed (layers that may occur unintentionally) In this embodiment, layers other than layers A, B, C, and the outermost layer are deposited in such a way that no other layers exist; that is, these layers are in contact with each other. However, when changing the layer to be deposited, changes in pressure and temperature within the deposition apparatus may occur unintentionally, resulting in the formation of unintended layers different from these layers.

[0037] 6.Base (1)Material The substrate used in this embodiment can be any known substrate material, as long as it does not hinder the achievement of the aforementioned objectives. Examples include cemented carbide (WC-based cemented carbide, including those containing WC and Co, and further including those with carbonitrides such as Ti, Ta, and Nb added), cermets (mainly composed of TiC, TiN, TiCN, etc.), and ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide).

[0038] (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.

[0039] 7.Measurement method (1) Methods for measuring the boundaries, average thickness, and composition of each layer, as well as the crystal structure and area fraction of the crystal grains. The grain boundaries of the (AlTi)CN layer are determined and the grains are identified in the following manner. Specifically, using a crystal orientation analyzer attached to a transmission electron microscope (TEM), an electron beam tilted at, for example, 0.5 to 1.0 degrees relative to the normal direction of the polished surface is irradiated in a precessional manner on a polished longitudinal section. The electron beam is scanned at arbitrary beam diameters and intervals, and electron diffraction patterns are continuously acquired to analyze the crystal orientation of each measurement point. The observation field can be exemplified as having a width of 50 μm in the direction parallel to the substrate surface (lateral direction) and the thickness of the coating layer (average thickness) in the longitudinal direction.

[0040] The conditions used to acquire the electron diffraction pattern in this 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 5.0 nm. 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 regular hexagonal shape can be used as an example of the region represented by these measurement points (hereinafter sometimes referred to as a pixel).

[0041] If there is an angular difference of 5 degrees or more in crystal orientation between adjacent pixels, or if only one of adjacent pixels exhibits a face-centered cubic structure of the NaCl type or a hexagonal structure of the wurtzite type, the edges of the region where these pixels meet are defined as grain boundaries. The area enclosed by these grain boundary edges is defined as a single crystal grain. However, pixels that exist alone, such as those with an orientation difference of 5 degrees or more from all adjacent pixels, or those for which there are no adjacent measurement points exhibiting a face-centered cubic structure of the NaCl type, are not considered 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.

[0042] For the analysis, a grain boundary is defined as a region where there is an orientation difference of 5 degrees or more between adjacent measurement points (pixels). However, a single pixel that has an orientation difference of 5 degrees or more from all adjacent pixels is not treated as a crystal grain; only pixels that are connected by two or more pixels are treated as crystal grains. In this way, by determining each crystal grain and identifying its crystal structure, the area ratio of wurtzite-type hexagonal crystal grains and NaCl-type face-centered cubic crystal grains in each layer can be determined.

[0043] By measuring with the aforementioned TEM, the boundary where the area ratios of the crystal structures of layers B and C differ can be defined. By measuring the area ratios of the crystal structures and performing compositional analysis across the defined boundary, the boundary region between layers B and C can be defined and the average thickness can be determined (for example, the average thickness can be measured at five or more locations). Furthermore, the average Al content of each layer (XB, XC) can be determined by averaging the analysis results obtained by irradiating the coating layer with an electron beam using Auger electron spectroscopy (AES) and performing line analysis in the thickness direction of the coating layer on multiple lines (for example, five or more lines). Furthermore, by using AES to irradiate the longitudinal section with an electron beam and performing multiple (e.g., 5 or more) line analyses in the thickness direction of the coating layer for layers A and B, the boundary between layers A and B can be defined and the average thickness of layers A and B can be determined (the average thickness is measured at, for example, 5 or more locations).

[0044] Furthermore, the average carbon content (Z, YB, YC) of each layer (A, B, and C) can be determined for each layer by secondary ion mass spectrometry (SIMS). Specifically, an ion beam is irradiated onto a 70 μm × 70 μm measurement area on the surface of the coating layer, and the carbon content in the depth (thickness) direction of the coating layer is measured by alternately repeating surface analysis with the ion beam and etching with a sputter ion beam. More precisely, for each layer, the average value is calculated by taking measurements at a pitch of 0.01 μm or less and over a length of at least 0.05 μm, starting from a point that penetrates 0.02 μm or more from the surface side of the coating layer. This is then repeated at five or more locations outside the aforementioned measurement area by irradiating with the ion beam to determine the average carbon content of each layer. Similarly, by determining the average content of Al, Ti, and N in each layer using SIMS, (Al XB Ti 1-XB ) and (C YB N 1-YB The ratio can be calculated.

[0045] (2)X-ray analysis When performing X-ray diffraction on a coating layer, The ratio of the sum of the diffraction line intensities of the 111 and 200 diffraction lines of the NaCl-type face-centered cubic crystal structure to the 100 diffraction line of the wurtzite-type hexagonal crystal structure. That is, if we consider the diffraction line intensity values ​​Ic(111) for the 111 diffraction line and Ic(200) for the 200 diffraction line of a face-centered cubic crystal structure of the NaCl type, and the diffraction line intensity value Ih(100) for the 100 diffraction line of a hexagonal crystal structure of the wurtzite type, Ih(100) / [Ic(111)+Ic(200)] It is more preferable that the relationship 0.1 ≤ Ih(100) / [Ic(111)+Ic(200)] ≤ 0.4 is satisfied. The reason for this is that if the above ratio falls below 0.1, the coating layer may become susceptible to brittle fracture due to impacts during machining, while a ratio exceeding 0.4 may result in a significant decrease in wear resistance.

[0046] The 100 diffraction line, 111 diffraction line, and 200 diffraction line referred to here are not lines observed individually for each of the coating layers, i.e., layers A, B, and C (including the outermost layer if present), when X-ray diffraction is performed on these layers, but rather the diffraction lines of these layers are observed overlapping.

[0047] Ih(100) is measured using the 100 diffraction line of AlN. This is because the peak detectable as the 100 diffraction line of (AlTi)CN in the wurtzite-type hexagonal crystal structure is the 100 diffraction line of AlN. In addition, in the X-ray diffraction pattern, the 111 diffraction line and 200 diffraction line of the crystal grains in the NaCl-type face-centered cubic crystal structure are also measured. Diffraction lines are In some cases, the peaks may appear separately in layers B and C. In such cases, the sum of the intensities of the peaks in layer B and C is calculated as "Ic(111) + Ic(200)". Note that the 100 diffraction line, 111 diffraction line, and 200 diffraction line refer to diffraction peaks treated as the (100) plane of the wurtzite-type hexagonal crystal structure, the (111) plane of the NaCl-type face-centered cubic crystal structure, and the (200) plane of the NaCl-type face-centered cubic crystal structure, respectively.

[0048] The following are examples of measurement conditions. Scanning axis: 2θ-θ X-ray source: Cu-Kα ray (1.541862Å) Detector: 0-dimensional detector (scintillation counter) Tube voltage: 45kV Tube current: 40mA Incident optical system: Use of mirrors Photodetector optics: Use of analyzer crystals (PW3050 / 60) Step: 0.03° Total time: 2 seconds Scan range (2θ): 10°~120°

[0049] 8. Manufacturing method The coating layer of the coating tool of this embodiment can be manufactured by chemical vapor deposition under the following manufacturing conditions, for example.

[0050] (1) Manufacturing of Layer A For example, depending on the type of layer, the manufacturing conditions are either 1) or 2) below. 1) Manufacturing conditions 1 TiN layer deposition Reaction gas composition (volume %) TiCl4: 3.0~6.0%, N2: 25.0~35.0%, H2: remainder Reaction atmosphere pressure: 4.0~12.0 kPa Reaction atmosphere temperature: 780~900℃

[0051] 2) Manufacturing conditions 2 Formation of TiCN layer Reaction gas composition (volume %) TiCl4:3.0~6.0%, N2:15.0~30.0% CH4 or CH3CN: 0.6-2.0%, H2: residual Reaction atmosphere pressure: 7.0~12.0 kPa Reaction atmosphere temperature: 780~900℃

[0052] (2) Manufacturing of Layer B Reaction gas composition (volume %) Gas group B1: TiCl4: 0.01~0.02%, AlCl3: 0.04~0.10%, N2:0.0~10.0%, C2H4:0.0~0.5%, H2:Remaining Gas group B2: NH3: 1.0~3.0%, H2: 25.0~35.5% Reaction atmosphere pressure: 4.0~5.0 kPa Reaction atmosphere temperature: 800~900℃ Supply cycle: 1~5 seconds, Gas supply time per cycle: 0.15~0.25 seconds Phase difference between the supply of gas group B1 and the supply of gas group B2: 0.10~0.20 seconds

[0053] (3) Manufacturing of the C layer Reaction gas composition (volume %) Gas group C1: TiCl4: 0.01~0.03%, AlCl3: 0.02~0.09% N2:0.0~10.0%, C2H4:0.0~0.5%, H2:Remaining Gas group C2:NH3:0.1~0.8%, H2:25.0~35.0% Reaction atmosphere pressure: 4.0~5.0 kPa, Reaction atmosphere temperature: 700~850℃ Supply cycle: 1~5 seconds, Gas supply time per cycle: 0.15~0.25 seconds, Phase difference between the supply of gas group C1 and the supply of gas group C2: 0.10~0.20 seconds [Examples]

[0054] Next, we will describe some examples. Here, as an example, we describe an application to an insert cutting tool using a WC-based cemented carbide as the base material. The base material may be made of the aforementioned material, and the tool shape may be a drill or an end mill.

[0055] As raw material powders, WC powder, TiC powder, TaC powder, NbC powder, Cr3C2 powder, and Co powder were prepared and blended as shown in Table 1. After adding wax and mixing in acetone with a ball mill for 24 hours, the mixture was dried under reduced pressure and then press-molded into a compact of a predetermined shape at a pressure of 98 MPa. This compact was then vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature within the range of 1420°C for 1 hour to produce substrates A to C made of WC-based cemented carbide with the insert shape of Mitsubishi Materials Corporation's JOMU140715ZZER-M.

[0056] Next, layers A, B, and C were sequentially deposited on the surfaces of these substrates A to C according to the manufacturing conditions shown in Tables 2 to 4, respectively, to obtain coated tools 1 to 8 of the examples shown in Table 5 (hereinafter referred to as Examples 1 to 8).

[0057] On the other hand, for comparison, layers A, B, and C were sequentially deposited on the surfaces of substrates A to C according to the manufacturing conditions shown in Tables 2 to 4, respectively, to obtain comparative example coated tools 1 to 8 (hereinafter referred to as comparative examples 1 to 8) shown in Table 6.

[0058] [Table 1]

[0059] [Table 2]

[0060] [Table 3]

[0061] [Table 4]

[0062] [Table 5]

[0063] [Table 6]

[0064] In Table 6, "-" indicates that there is no matching entry.

[0065] Next, for each of the above-mentioned Examples 1-8 and Comparative Examples 1-8, the following dry face milling tests of stainless steel were performed until a defect occurred, with the tool steel cutter tip, which has a cutter diameter of 63 mm, clamped with a fixing jig. Table 7 shows the results of the cutting tests.

[0066] Machining test: Dry face milling Workpiece material: SUS304 block material: 45mm wide Cutting speed: 160m / min Cut: 1.5mm Feed rate: 1.5mm / blade

[0067] [Table 7]

[0068] In Table 7, "Maximum machining time (minutes)" refers to the machining time until damage occurs. processing Every minute after the start of the test, the presence or absence of chipping and delamination due to plastic deformation was visually observed, the wear width of the flank surface (including chipping) was measured, and the time to reach the end of service life (maximum processing time) was determined. The service life is defined as the wear width of the flank surface being 0.2 mm or more, and the maximum machining time is defined as the wear width exceeding 0.2 mm. Cutting processing The elapsed time from the start of the test (measurement time) was defined as the time from the start of the test when the flank wear width at the time elapsed from the start of the test (measurement time) and the flank wear width at the time immediately preceding the measurement time were linearly approximated to obtain a flank wear width of 0.2 mm.

[0069] As is clear from Table 7, all of the examples had long maximum machining times and demonstrated excellent durability even in high-feed cutting of stainless steel. In contrast, the comparative examples all had short maximum machining times and reached the end of their lifespan in a short time.

[0070] Furthermore, the surface-coated cutting tool according to the present invention is expected to exhibit excellent durability even when used to cut materials that also have high weldability and are subjected to large thermal and mechanical loads on the cutting edge, such as stainless steel, Ni-based heat-resistant alloys, and Ti alloys.

[0071] 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]

[0072] 1 Base 2 A-level 3B Floor 4 C layer 5 most surface layer 6. Covering layer

Claims

1. The substrate has a coating layer on its surface, (a) The coating layer has, in order from the surface of the substrate toward the tool surface, layers A, B, and C that are in contact with each other, and the sum of the average thicknesses of these three layers is 0.7 to 21.0 μm. (b) The A layer has an average thickness of 0.1 to 2.0 μm and is a layer containing Ti nitride or carbonitride, (c) The B layer has an average thickness of 0.1 to 0.5 μm, and (Al ＸＢ Ti １－ＸＢ ) (C ＹＢ N １－ＹＢ The average composition is (0.80 ≤ XB ≤ 0.95, 0.00 ≤ YB < 0.05), and in the longitudinal section of the B layer, grains having a wurtzite-type hexagonal crystal structure account for 30 area % or more, with the remainder consisting of grains having a NaCl-type face-centered cubic crystal structure. (d) The C layer has an average thickness of 0.5 to 20.0 μm, and (Al ＸＣ Ti １－ＸＣ ) (C ＹＣ N １－ＹＣ The C layer has an average composition of (0.65 ≤ XC ≤ 0.90, 0.00 ≤ YC < 0.05), and in the longitudinal section of the C layer, grains having a wurtzite-type hexagonal structure account for 5 area % to 25 area % of the total area, with the remainder consisting of grains having a NaCl-type face-centered cubic structure. A surface-coated cutting tool characterized by the following features.

2. In the coating layer, the diffraction line intensity values ​​Ic(111) and Ic(200) of the 111 diffraction line of the NaCl-type face-centered cubic crystal grains, and the diffraction line intensity value Ih(100) of the 100 diffraction line of the wurtzite-type hexagonal crystal grains are, 0.1≦Ih(100) / [Ic(111)+Ic(200)]≦0.4 The surface-coated cutting tool according to claim 1, characterized in that it is the same as described in claim 1.

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