Surface coated cutting tool excellent in peel resistance and wear resistance

In the present invention, since the surface of the hard coating layer is provided with a porous shape oxynitride layer having excellent lubricity and heat dissipation under wet cutting conditions, it is particularly hard to generate high heat such as various Ni-based alloys and Ti-based alloys. A surface that does not easily generate high heat even when cutting difficult-to-cut materials, suppresses peeling of the hard coating layer due to welding, and exhibits excellent peeling resistance and chipping resistance over a long period of time. It relates to a coated cutting tool (hereinafter referred to as a coated tool).

In general, covering tools include slow-away chips that are detachably attached to the tip of a cutting tool for turning and planing of various types of work materials such as steel and cast iron, and drilling and cutting of the work materials. There are drills and miniature drills used in the above, as well as solid type end mills used for surface cutting, grooving, shoulder processing, etc. of the work material, and the slow way tip can be detachably attached to the solid type. Slow-away end mill tools that perform cutting in the same way as end mills are known.

Further, on the surface of a tool substrate made of high-speed tool steel, cemented carbide, cermet, etc., the thickness of the uppermost layer is in the range of 0.1 to 1.5 μm, and the width is 0.1 to 10.0 μm. Cutting tools in which a coating layer with a level pore is formed are known.

Further, in the conventional coating tool, after forming TiN or TiAlN by the arc ion plating method, the uppermost layer is formed with a film thickness of 0.1 to 1.5 μm, and the reaction gas N is formed._２The metal of Ti, which is a molten particle ejected from the droplet formed on the surface of the uppermost layer by adding Ar, is pressed against the arc ion plating surface with an abrasive containing ultrafine alumina powder or zirconia fine powder. 0.5-2) x 10^５Blast treatment (cleaning treatment) that blows weakly at about Pa is performed, or ultra-fine diamond abrasive grains are blasted on the surface of the arc ion plating. The metal of Ti, which is a molten particle, is removed by aerowrap. It is also known that it is produced by forming a coating film having a width of about 0.1 to 10.0 μm and a depth of 0.1 to 1.5 μm on the surface.

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2005-153072</text></patcit></p>

<p num="0006"> In recent years, the performance and automation of cutting equipment has been remarkable, while there is a strong demand for labor saving, energy saving, and cost reduction for cutting, and along with this, cutting speed is increased and the type of work material is used. There is a strong demand for a versatile covering tool that is not limited to the above, but in the conventional covering tool, a long life is extended when a hard difficult-to-cut material such as an AlSi alloy is cut. Although shown, this occurs during high-speed cutting of hard-to-cut materials such as various Ni-based alloys and Ti-based alloys, which have low thermal conductivity and tend to retain heat on the tool cutting edge during cutting. Welding to the tool cutting edge is likely to occur due to extremely high heat generation, which causes peeling of the hard coating layer and chipping, so that the service life is reached in a relatively short time.</p>

<p num="0007"> Therefore, from the above-mentioned viewpoints, the present inventors have earnestly aimed to develop a coating tool in which the hard coating layer exhibits excellent peeling resistance and chipping resistance in the high-speed cutting of the hard-to-cut material. As a result of the research, the following findings were obtained.</p><p num="0008"> First, in the conventional coating tool (Patent Document 1), a TiN layer or a TiAlN layer is formed by the arc ion plating method, and this is used for cutting hard difficult-to-cut materials such as AlSi alloys. If this is the case, no particular problem will occur, but when this is used for high-speed cutting of hard-to-cut materials such as various Ni-based alloys and Ti-based alloys, the effect of retaining cutting oil is not sufficient. It was found that welding occurs due to the extremely high heat generated by the welding, and the hard coating layer is peeled off due to the welding.</p><p num="0009"> Therefore, the present inventors have focused on a TiAlNO layer structure that is less likely to cause welding and has a high cutting oil retention effect, and as a result, it is shown in Patent Document 1 when forming a TiAlN layer. Instead of simply forming a film by the arc ion plating method, a hard film of TiAlN is formed by the arc ion plating method, and then oxygen plasma treatment is performed using an assist gun under specific conditions to form a hard coating layer. By forming a thin oxide film, which is an insulator that easily stores positive charges, on the surface and causing insulation destruction due to arc discharge mediated by oxygen anions or electrons in the plasma formed in the substrate and its surroundings. A TiAlNO layer having fine pores distributed with a meandering path can be formed on the surface layer, and the hard coating layer thus obtained can be used for high-speed cutting of hard-to-cut materials such as various Ni-based alloys and Ti-based alloys. In the processing as well, it has been found that a TiAlNO layer that is less likely to generate heat and is less likely to be welded can be formed due to the porous surface structure and the high cutting oil retention effect due to the micropore shape.</p><p num="0010"> Specifically, FIG. 1 shows a schematic plan view of the arc ion plating apparatus. A cathode electrode (evaporation source) made of a TiAl alloy is arranged in the arc ion plating apparatus to create an atmosphere inside the apparatus. , Ar atmosphere, arc discharge, N as reaction gas_２After forming a hard film, oxygen plasma treatment is performed with an assist gun at a discharge voltage of 130 V, a filament current of 36 A, a coil current of 16 A, and a bias voltage of 100 V. Since the oxynitride layer having a porous shape that greatly improves the heat dissipation efficiency can be formed in the upper layer, welding due to high heat generation generated at the time of cutting is less likely to occur, and peeling of the coating film due to welding can be suppressed.</p><p num="0011"> As a result, the coating tool as a result has excellent oil retention and heat dissipation properties of the cutting fluid on the upper layer, especially in wet high-speed cutting of hard-to-cut materials such as various Ni-based alloys and Ti-based alloys that generate extremely high heat. The oxynitride layer having welding resistance and the nitride layer having excellent wear resistance corresponding to the oxygen plasma untreated portion are compatible with each other in the lower layer, so that the hard coating layer is peeled off due to welding. It was found that by suppressing the above, excellent peeling resistance and wear resistance can be exhibited for a long period of time.</p><p num="0012"> The present invention has been made based on the above findings. "On the outermost surface of a tool substrate made of tungsten carbide based cemented carbide or titanium nitride based cermet (Ti)_1-XAl_X) (N_1-YO_Y) (However, in terms of atomic ratio, X shows 0.40 to 0.75 and Y shows 0.1 to 0.4), and has an average layer thickness of 0.5 to 3.4 μm. Ti and Al oxynitride layers, in the lower layer (Ti_1-XAl_X) N (where X indicates 0.40 to 0.75 in atomic ratio) and coated with a nitride layer of Ti and Al having an average layer thickness of 0.8 to 4.0 μm. Is a cutting tool The oxynitride layer has a porous shape having micropores distributed with a meandering path in the depth direction from the surface, and the diameter of a circle inscribed in the micropores when the oxynitride layer is observed from the surface. When the pore diameter of the micropores is used, the pore diameter of the micropores is 0.1 to 1.5 μm. The specific surface area of the oxynitride layer is 0.4 to 1.0 m.^２/ G A surface-coated cutting tool characterized in that the area ratio of the micropore openings to the area on the substrate when the oxynitride layer is observed from the surface is 0.05 to 0.3. It is characterized by.</p><p num="0013"> Next, the covering tool of the present invention will be described in detail. Composition of oxynitride layer of Ti and Al having a porous shape on the outermost surface: When the average oxygen content ratio Y (however, atomic ratio) in the total amount of nitrogen and oxygen of the surface oxynitride layer having a porous shape is 0.1 or less, the lubricity formed during cutting is improved. Oxides are not sufficiently formed, and if it is 0.4 or more, a large amount of oxides are formed, and the structure becomes brittle, or the lattice strain of the structure increases due to the solid dissolution of a large amount of oxygen, and the structure becomes fragile. Therefore, the average oxygen content ratio Y of the oxynitride layer was set to 0.1 to 0.4.</p><p num="0014"> Further, if the content ratio X (however, atomic ratio) of Al in the total amount of Ti and Al is less than 0.40, high hardness and oxidation due to lattice strain caused by Al substitution at Ti sites in the TiN lattice. Oxidation resistance by the protective film cannot be obtained, and if it is 0.75 or more, hexagonal structural acid nitrides that do not have sufficient hardness are formed, and the desired high-temperature toughness and high-temperature strength cannot be obtained. The Al content ratio X was set to 0.40 to 0.75. Average thickness of Ti and Al oxynitride layers having a porous shape on the outermost surface: The TiAlNO layer formed on the outermost surface of a tool substrate made of a tungsten carbide-based cemented carbide or a titanium nitride-based cermet does not have a sufficient cutting fluid retention effect when the average layer thickness is less than 0.5 μm. If the average layer thickness exceeds 3.4 μm, peeling due to welding can be suppressed in high-speed cutting of hard-to-cut materials such as Ni-based alloys and Ti-based alloys, but chipping of the cutting edge is likely to occur. Therefore, the average layer thickness was set to 0.5 to 3.4 μm. Composition of the lower nitride layer: If the content ratio X (however, atomic ratio) of Al in the total amount of Ti and Al in the nitride layer of Ti and Al constituting the lower layer is less than 0.40, Al substitution at the Ti site in the TiN lattice Hexagonal structure nitride, which does not have sufficient hardness when it is 0.75 or more, cannot obtain high hardness due to lattice strain and oxidation resistance due to the dense oxide protective film formed during cutting. Since it was formed and the desired high-temperature toughness and high-temperature strength could not be obtained, the Al content ratio X was set to 0.40 to 0.75. Average thickness of nitride layer: If the average layer thickness of the nitride layer corresponding to the untreated plasma portion is less than 0.8 μm, the wear resistance of the nitride layer cannot be exhibited, while the average layer thickness is 4.0 μm. If it exceeds this value, chipping of the cutting edge is likely to occur, so the average layer thickness was set to 0.8 to 4.0 μm. Micropore shape and pore diameter: The micropores of the oxynitride layer are not spherical micropores but have a shape having a meandering path in the depth direction from the surface of the oxynitride layer. When the diameter of the circle inscribed in the micropores when the oxynitride layer is observed from the surface is defined as the pore diameter of the micropores, if the average pore diameter is less than 0.1 μm, it becomes difficult to hold a sufficient amount of cutting fluid. On the other hand, if the average pore diameter exceeds 1.5 μm, the retention effect of the cutting fluid due to the capillary phenomenon becomes small, and the structure cannot withstand the load during cutting and is destroyed. Therefore, the average pore diameter is 0.1 to 1. It was defined as 5.5 μm. Specific surface area: Specific surface area, that is, the area per unit weight is 0.4 m^２If it is less than / g, the surface area that gives the capillary force to hold a sufficient cutting fluid is not sufficient, so that welding due to high heat generation is likely to occur and the cutting fluid is peeled off. Also, 1.0m^２Those satisfying / g or more have very small pore diameters and a large number of micropores, and the structure is destroyed because the oxynitride layer has poor wear resistance. In addition, since the amount of oil retained is reduced, the specific surface area of the oxynitride layer is 0.4 to 1.0 m.^２It was set as / g. The specific surface area referred to here is an atomic force microscope assuming that the weight of the oxynitride layer in a unit area on the substrate is the same as the weight of the hard coating layer before the plasma treatment deformed by the oxygen plasma treatment. It is a value obtained by dividing the surface area measured by the above-mentioned assumed weight.</p><p num="0015"> Further, in the conventional micropores that are close to a spherical shape as disclosed in the prior art, the weight and the surface area cannot be compatible with each other, and the cutting oil holding effect due to the capillary phenomenon peculiar to the present invention cannot be obtained.</p><p num="0016"> That is, conventionally, micropores are produced by mechanical / scientific removal of droplets or by precipitating and dissolving a carbon compound inside a hard film, but these methods are close to spheres and spheres. Only shaped holes can be made. However, according to the present invention, since it is possible to produce elongated fine pores that are distributed while bending in the depth direction, the high holding effect of the cutting fluid due to the large surface area and the small pore diameter has resulted in the prior art. The effect of extending the cutting life can be expected from the fine holes.</p><p num="0017"> In general, it is known that the height of the liquid level when a liquid is held in a cylindrical tube due to the capillary phenomenon becomes higher as the inner diameter of the tube becomes smaller. Therefore, the smaller the inner diameter, the higher the amount of the cutting fluid held. .. However, if only spherical holes and holes having a shape close to a spherical shape can be produced, the inner diameter and volume of the spherical holes have a simple increasing relationship, so that a sufficient force for holding the cutting fluid and a sufficient amount for holding the cutting fluid cannot be compatible with each other.</p><p num="0018"> That is, in the prior art, the effect of the capillary phenomenon for retaining the cutting fluid is low, and the cutting fluid cannot be sufficiently retained. Area ratio of the micropore openings to the area on the substrate when the oxynitride layer is observed from the surface: If the area ratio of the fine hole openings is small, the holding effect of the cutting fluid becomes small. On the other hand, if it is large, the structure cannot withstand the load during cutting and is destroyed. Therefore, the area ratio of the micropore openings to the area on the substrate when the oxynitride layer is observed from the surface is set to 0.05 to 0.3.</p><p num="0019"> The method for manufacturing the covering tool of the present invention will be described below.</p><p num="0020"> For the hard coating layer as described above, for example, the substrate is charged into an arc ion plating (AIP) device, which is one of the physical vapor deposition devices shown in the schematic explanatory view in FIG. 1, and the inside of the device is charged with a heater, for example. A cathode electrode (evaporation source) made of a TiAl alloy having a predetermined composition is placed in the apparatus while heated to a temperature of 500 ° C., and an electric current, for example, is generated between the anode electrode and the cathode electrode (evaporation source). : An arc discharge was generated under the condition of 90 A, and at the same time, nitrogen gas was introduced into the apparatus as a reaction gas to create a reaction atmosphere of, for example, 2 Pa, while a bias voltage of, for example, -100 V was applied to the substrate. A hard film made of TiAlN is formed by vapor deposition under the conditions. Then, using an assist plasma gun, for example, a discharge voltage of 130 V, a filament current of 36 A, a coil current of 16 A, and an Ar-introduced gas of 15 ml / min. , O_２Introduced gas 30 ml / min. , Oxygen plasma treatment is performed at a bias voltage of 100 V to form a thin oxide film, which is an insulator that easily stores positive charges, on the surface of the hard coating layer, and oxygen anions or electrons in the plasma formed in the substrate and its surroundings. By causing dielectric breakdown due to arc discharge mediated by, the upper layer is an oxynitride layer with micropores distributed with a meandering path, and the lower layer is from a nitride layer corresponding to an oxygen plasma untreated part. A hard coating layer can be produced. At this time, if the discharge voltage, filament current, and bias are large, the arc discharge becomes strong, the fine pores are deep, and the pore diameter is also large.</p>

<p num="0021"> The coating tool of the present invention cuts into an oxynitride layer in wet cutting in order to modify the hard coating layer into an oxynitride layer having fine pores by performing plasma treatment in an oxygen atmosphere. Since the oil agent permeates and the heat dissipation efficiency to the cutting oil agent is greatly improved, welding due to extremely high heat generation generated during cutting is unlikely to occur, and peeling of the coating film due to welding can be suppressed. In addition, by containing oxygen in the surface layer, the formation of an oxide having a low coefficient of friction during cutting is promoted, the discharge property of chips and the like entering the micropores is improved, and the wear resistance of the oxynitride layer is improved. Since the properties are improved, the porous shape is maintained for a long period of time, and the oxynitride layer and the nitride layer can be compatible with each other in a well-balanced manner, high heat is generated under wet cutting conditions that generate high heat such as Ti alloy. As a result, welding peeling is suppressed and the effect of extending the life is achieved.</p>

<figref num="1">It is a schematic plan view of the arc ion plating (AIP) apparatus used for forming the hard coating layer of the coating tool of this invention.</figref><figref num="2">A scanning electron micrograph (magnification: 1000 times) of the surface structure of the oxynitride layer of the coated chip 16 of the present invention is shown.</figref>

Next, the covering tool and the method for manufacturing the covering tool according to the present invention will be specifically described with reference to Examples.

<p> As raw material powders, WC powder, TiC powder, ZrC powder, TaC powder, NbC powder, and Cr, all of which have an average particle size of 1 to 3 μm._３C_２Powders, TiN powders, and Co powders are prepared, these raw material powders are blended into the compounding composition shown in Table 1, wet-mixed with a ball mill for 72 hours, dried, and then press-molded into a green compact at a pressure of 100 MPa. Then, this green compact was sintered in a vacuum of 6 Pa at a temperature of 1400 ° C. for 1 hour, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to ISO standard CNMG120408. Tool bases A-1 to A-8 made of WC-based cemented carbide having the shape of the slow-away tip of No. 1 were formed.</p><p> Further, as raw material powders, TiCN (TiC / TiN = 50/50 by weight) powder having an average particle size of 0.5 to 2 μm, Mo._２C powder, ZrC powder, NbC powder, TaC powder, WC powder, Co powder, and Ni powder are prepared, these raw material powders are blended into the blending composition shown in Table 2, wet-mixed with a ball mill for 24 hours, and dried. After that, it was press-molded into a green compact at a pressure of 100 MPa, and this green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour. : 0.03 honing process was performed to form TiCN-based cermet tool substrates B-1 to B-6 having a throw-away tip shape of ISO standard CNMG120408. (A) Next, each of the tool substrates A-1 to A-8 and B-1 to B-6 is ultrasonically washed in acetone and dried, and the arc ion plating apparatus shown in FIG. 1 is shown. For forming a hard coating layer as cathode electrodes (evaporation sources) on both sides of the rotary table, which are mounted along the outer peripheral portion in a radial direction from the central axis of the rotary table and which face each other across the rotary table. Place the Ti-Al alloy and (B) First, while the inside of the device is exhausted and kept in a vacuum of 0.1 Pa or less, the inside of the device is heated to 500 ° C. with a heater, and then the tool substrate is rotated while rotating on the rotary table at 1000 V. A DC bias voltage is applied, and a current of 100 A is passed between the cathode electrode and the anode electrode to generate an arc discharge, so that the surface of the tool substrate is bombard-cleaned. (C) Next, nitrogen gas is introduced as a reaction gas into the apparatus to create a reaction atmosphere of 4 Pa, and a DC bias voltage of -100 V is applied to the tool substrate that rotates while rotating on the rotary table. An arc discharge is generated by passing a current of 120 A between the Ti-Al alloy of the cathode electrode and the anode electrode, and a (Ti, Al) N layer is vapor-deposited on the surface of the tool substrate, and then the cathode electrode (evaporation source). ) And stop the arc discharge between the anode electrode, (D) Then, using the assist gun in the device, the discharge voltage was 130 V, the filament current was 36 A, the coil current was 16 A, and the Ar introduced gas was 15 ml / min. , O_２Introduced gas 30 ml / min. By performing oxygen plasma treatment at a bias voltage of 100 V, an oxynitride layer having a target layer thickness, a predetermined micropore, and a porous shape having an average oxygen content, which is also shown in Table 3, is hard-coated. Formed on the surface of The covering tools 1 to 18 of the present invention (hereinafter referred to as chips 1 to 18 of the present invention) having a throwaway tip shape specified in ISO / CNMG120408 were manufactured.</p><p> For the purpose of comparison, each of the tool bases A-1 to A-8 and B-1 to B-6 was bombard-cleaned in the same manner as in the present invention. Then, as a reaction gas, nitrogen gas was introduced into the apparatus to create a reaction atmosphere of 4 Pa, and a DC bias voltage of -100 V was applied to the tool substrate rotating while rotating on the rotary table, and the cathode electrode was used. A current of 120 A is passed between the TiAl alloy and the anode electrode to generate an arc discharge, and a TiAlN layer as a single layer having the target composition and target layer thickness shown in Table 4 is deposited on the surface of the tool substrate. After the formation, an Ar gas is added to the nitrogen gas to form a TiAlN layer on which a Ti metal droplet is formed, and the Ti metal is removed by a blast treatment. Comparative example covering tools 1 to 14 (hereinafter, referred to as Comparative Example chips 1 to 14) having a throwaway tip shape specified in ISO / CNMG120408 were manufactured.</p><p> For reference, the same apparatus as the apparatus for manufacturing the coated chips 1 to 18 of the present invention shown in FIG. 1 is used to form a film under different compositions, film thicknesses, and assisted plasma gun conditions from those of the coated chips 1 to 18 of the present invention. As a result, reference covering tools (hereinafter referred to as reference covering tips) 1 to 4 having a throwaway tip shape specified in ISO / CNMG120408 shown in Table 4 were manufactured.</p><p> Next, the hard coating layers of the chips 1 to 18 of the present invention and the reference coating chips 1 to 4 were cross-sectionally measured with a scanning electron microscope to determine the film thickness of the oxynitride layer and the film thickness of the nitride layer. .. Further, the diameter of the circle inscribed in the micropores when observed from the surface with a scanning electron microscope was determined as the pore diameter of the micropores. Further, the surface area of the oxynitride layer in the unit area on the base material is measured by an interatomic force microscope, and the weight of the oxynitride layer in the unit area on the base material is deformed by oxygen plasma treatment to be a hard coating layer before plasma treatment. The specific surface area was determined on the assumption that it was the same as the weight of. Further, the oxynitride layer was observed from the surface with a scanning electron microscope, and the area of the micropore openings existing in a unit area on the substrate was determined and used as an area ratio.</p><p> These measured values are shown in Tables 3 and 4.</p><p> Further, the cross-sections of the hard coating layers of Comparative Examples Chips 1 to 14 were measured with a scanning electron microscope, and the film thickness of the entire hard coating layer and the depth at which the pores were located were determined. In addition, the width of the pore was determined by using a scanning electron microscope with the diameter of the circle inscribed in the pore as the width of the pore. These measured values are shown in Table 4.</p><p> Further, the composition of the wear-resistant hard layer constituting the hard coating layers of the chips 1 to 18 of the present invention, the chips 1 to 14 of the comparative examples and the reference coating chips 1 to 4 was measured by an electron probe microanalyzer (EPMA), and each of them was measured. It showed substantially the same composition as the target composition.</p><p> Further, when the average layer thickness of the hard coating layer was measured in cross section using a scanning electron microscope, all showed substantially the same average value (average value at 5 locations) as the target layer thickness.</p><p> Next, with the various coated tips described above screwed to the tip of the tool steel cutting tool with a fixing jig, the tips 1 to 18 of the present invention, the tips 1 to 14 of the comparative examples, and the reference coated tips 1 to 1 About 4 Work Material: Round bar of Ti-6% Al-4% V alloy by mass, Cutting speed: 140 m / min. , Notch: 1.0 mm, Feed: 0.3 mm / rev. , Cutting time: 5 minutes, Wet high-speed cutting test of Ti-based alloy under the condition of (cutting condition A) (normal cutting speed and feed are 120 m / min. And 0.2 mm / rev, respectively), and the flank surface of the cutting edge. The wear width was measured.</p><p> The measurement results are shown in Table 5.</p><p><tables num="1"><img id="000002" he="182" wi="103" file="2012192513.tif" img-format="tif" img-content="drawing" /></tables></p><p><tables num="2"><img id="000003" he="185" wi="91" file="2012192513.tif" img-format="tif" img-content="drawing" /></tables></p><p><tables num="3"><img id="000004" he="128" wi="159" file="2012192513.tif" img-format="tif" img-content="drawing" /></tables></p><p><tables num="4"><img id="000005" he="126" wi="160" file="2012192513.tif" img-format="tif" img-content="drawing" /></tables></p><p><tables num="5"><img id="000006" he="183" wi="90" file="2012192513.tif" img-format="tif" img-content="drawing" /></tables> From the results shown in Table 5, in addition to the nitride layer having excellent wear resistance, the oxynitride layer having fine pores distributed with a meandering path has excellent oil retention and welding resistance of the cutting oil. The coated tool of the present invention exhibits excellent peeling resistance and wear resistance in high-speed cutting accompanied by high heat generation of hard-to-cut materials such as various Ni-based alloys and Ti-based alloys.</p><p> On the other hand, in the conventional coated tool, as shown in Table 5, the fine holes constituting the oxynitride layer are not distributed with a meandering path, so that the oil retention property of the cutting fluid is inferior and the hard-to-cut material is difficult to cut. The peeling of the hard coating layer cannot be suppressed under high-speed cutting conditions accompanied by high heat generation, and the wear resistance is inferior.</p><p> In the above embodiment, the performance of the hard coating layer was evaluated using a slow way tip, but it goes without saying that the same result can be obtained with a drill, a miniature drill, an end mill, or the like.</p>

As described above, according to the covering tool of the present invention and the manufacturing method thereof, not only cutting under normal cutting conditions such as various steels and cast irons, but also high speed of the hard difficult-to-cut material accompanied by particularly high heat generation. It exhibits excellent peeling resistance and abrasion resistance even in cutting, and shows excellent cutting performance over a long period of time. Therefore, it improves the performance and automation of cutting equipment, and saves labor and energy in cutting. Furthermore, it is possible to fully satisfy the cost reduction.