JP2004268251A - Surface coated cutting tool and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool of long service life having high abrasion resistance by preventing generation of peeling and chipping of covering during a cutting process in cutting a difficult-to-cut material such as cast iron including mill scale, hard grain phase even under severe conditions. <P>SOLUTION: This cutting tool comprises a second layer 3 including at least Al, Ti, W, and Co between a first layer 2 consisting of a single layer or a double layer of nitride, carbide, carbonitride, or carbonate nitride of titanium on a surface of a tungsten carbide-base cemented carbide base material and a third layer 4 consisting of aluminum oxide. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a surface-coated cutting tool in which a hard coating layer having improved interlayer adhesion having excellent chipping resistance and film peeling resistance is formed on the surface and a method for producing the same, and particularly to black scale and hard particle phase. TECHNICAL FIELD The present invention relates to a surface-coated cutting tool having excellent cutting characteristics when cutting a difficult-to-cut material such as cast iron containing steel and a method for manufacturing the same.

2. Description of the Related Art Conventionally, a cutting tool that has been widely used for metal cutting includes at least one of metals of Group 4a, 5a, and 6a of the periodic table, particularly a hard phase mainly composed of WC (tungsten carbide) and Co (cobalt). A hard coating layer such as a TiC layer, a TiN layer, a TiCN layer, and an Al ₂ O ₃ layer is formed as a single layer on the surface of a cemented carbide or a hard alloy such as a cermet, which is composed of a binder phase of an iron group metal such as Ni or nickel (nickel). Alternatively, a surface-coated cutting tool formed by applying a plurality of layers is used, and among these, a cutting tool formed in the order of a combination of a TiC layer, a TiN layer and a TiCN layer (a titanium-based coating layer) -an aluminum oxide layer is frequently used. I have.

  These surface-coated cutting tools are mainly used for cutting cast iron, carbon steel, etc., but in particular, delamination between hard coating layers due to low interlayer adhesion between the titanium-based hard layer and the aluminum oxide layer of the hard coating layer. There is a problem that chipping occurs and the wear resistance of the cutting tool is reduced.

  Thus, in Patent Document 1, after forming a titanium-based hard layer including a TiCN layer, a heat treatment is performed in a hydrogen atmosphere of 10 to 100 torr at a temperature of 850 to 1100 ° C. for 1 to 5 hours to obtain a TiCN. W and Co are diffused and contained in the crystal grain boundaries to improve the interlayer adhesion of the hard layer.

Further, in Patent Document 2, between a TiCN layer and an Al ₂ O ₃ layer, the highest diffraction peak height is obtained at a diffraction angle (2θ) of 24.0 ± 1 degree by X-ray diffraction using Cuka radiation as a radiation source. By interposing a chemical vapor deposition or physical vapor deposition Ti ₂ O ₃ layer showing an X-ray diffraction pattern with an average thickness of 0.1 to 2 μm, the interlayer adhesion between the TiCN layer and the Al ₂ O ₃ layer is improved. ing.
Japanese Patent No. 3269305 JP-A-11-269650

  However, according to the method disclosed in Patent Document 1, the adhesion between the titanium-based hard layer and the aluminum oxide layer is insufficient, particularly when cutting a work material such as cast iron that requires impact resistance. there were.

Further, the method of interposing a titanium oxide between the TiCN layer and the Al ₂ O ₃ layer disclosed in Patent Document 2 cannot cope with recent high-load processing.

  Therefore, the present invention has been made in order to solve the above-described problems, the purpose is, particularly when cutting difficult-to-cut materials such as black iron or cast iron containing a hard particle phase, when cutting under severe conditions. Another object of the present invention is to provide a long-life cutting tool having excellent wear resistance by preventing peeling and chipping of a hard coating layer during cutting.

  As a result of studying the above problem, the present inventors have found that a surface of a tungsten carbide-based cemented carbide base material is formed of a single layer and / or a plurality of layers of titanium nitride, carbide, carbonitride, and carbonitride. The presence of the second layer containing at least Al, Ti, W and Co between the first layer and the third layer made of aluminum oxide allows for the simple formation of titanium nitride, carbide, carbonitride, and carbonitride. As a result of being able to improve the interlayer adhesion between the layer and / or the first layer consisting of multiple layers and the third layer consisting of aluminum oxide and the base material and the first layer, the adhesion strength of the hard coating layer is improved, It has been found that chipping and film peeling during cutting can be suppressed.

  Further, it is preferable that the second layer is formed by diffusing any of the elements in the base material, the first layer, and the third layer.

  Further, it is preferable that the average film thickness is 0.05 to 4 μm assuming that the second layer is intermittent and the second layer is continuous and uniform.

In the Auger electron spectroscopy data of the second layer, the peak intensity of Al near 1400 eV, the peak intensity of W near 1750 eV, and the peak intensity of Co near 800 eV were defined as I _Al , I _W , and I _Co , respectively. At this time, it is desirable that I _W / I _Al = 0.1 to 0.5 and I _Co / I _Al = 0.1 to 0.5.

  Further, it is preferable that the uppermost layer of the first layer is a streaky titanium carbonitride layer.

  The average thickness of the striped titanium carbonitride layer is preferably 0.5 to 15 μm.

  Further, it is desirable that the lowermost layer of the first layer is formed of a granular titanium nitride layer.

  The average thickness of the titanium nitride layer is desirably 0.5 to 3 μm.

  Further, it is desirable that the aluminum oxide of the third layer is a κ-type crystal or a κ-type crystal accounts for 50% by weight or more, and the remainder is a mixed crystal composed of an α-type crystal.

  Further, it is desirable that the concentration of W and Co on the extreme surface of the tungsten carbide-based cemented carbide base material is higher than that inside the base material.

  Further, it is desirable that the W and Co concentrations in the second layer be at least twice as high as the W and Co concentrations in the first layer and the third layer.

  The method of manufacturing a surface-coated cutting tool according to the present invention includes the steps of: forming, on a surface of a tungsten carbide-based cemented carbide base material, a single layer or a multilayer of titanium nitride, carbide, carbonitride, and carbonitride; Layer and a third hard layer made of aluminum oxide are sequentially formed, and then heat-treated at a processing temperature of 850 to 1100 ° C. for 1 to 10 hours in a hydrogen and / or nitrogen atmosphere of 1.3 to 40 kPa. Forming a second layer mainly containing titanium (Ti), aluminum (Al), tungsten (W) and cobalt (Co) between the first layer and the third layer. is there.

  According to the surface-coated cutting tool according to the present invention, titanium nitride, carbide, carbonitride, the first layer consisting of a single layer and / or multiple layers of carbonitride, between the third layer consisting of aluminum oxide By the existence of the second layer containing at least Al, Ti, W, and Co, the first layer consisting of a single layer or multiple layers of titanium nitride, carbide, carbonitride, and carbonitride and aluminum oxide The interlayer adhesion between the resulting third layers can be improved, and tool damage such as chipping and film peeling during cutting can be suppressed.

  Further, according to the method for manufacturing a surface-coated cutting tool according to the present invention, a single layer or a plurality of titanium nitride, carbide, carbonitride, and carbonitride is formed on the surface of the tungsten carbide-based cemented carbide base material. After sequentially forming a first hard layer made of a first layer and a third hard layer made of aluminum oxide, in a hydrogen and / or nitrogen atmosphere of 1.3 to 40 kPa, a treatment temperature: 1 to 10 at 850 to 1100 ° C. Heat treatment for a time to form a second layer mainly containing titanium (Ti), aluminum (Al), tungsten (W) and cobalt (Co) between the first layer and the third layer. It is possible to easily improve the interlayer adhesion between the first layer composed of a single layer or multiple layers of titanium nitride, carbide, carbonitride, and carbonitride and the third layer composed of aluminum oxide. Chip in cutting The tool damage packaging and film peeling can be easily suppressed.

  FIG. 1 is a conceptual view of an example of the surface-coated cutting tool of the present invention, FIG. 2 is a schematic enlarged cross-sectional view of a main part in the vicinity of a second layer in FIG. This will be described with reference to FIG. 3, which is a schematic enlarged cross-sectional view of a main part in the vicinity of the interface, and FIG.

  According to FIG. 1, the surface-coated cutting tool of the present invention comprises a single- and / or multi-layer of titanium nitride, carbide, carbonitride, and carbonitride on a tungsten carbide-based cemented carbide base material 1. 1 and a hard coating layer 1 in which a third layer 4 made of aluminum oxide is sequentially formed.

  In the present invention, it is assumed that the second layer 3 containing at least titanium (Ti), aluminum (Al), tungsten (W) and cobalt (Co) exists between the first layer 2 and the third layer 4. The second layer 3 plays a role of an intermediate layer, improves the interlayer adhesion between the first layer 2 and the third layer 4, increases the adhesive strength of the hard coating layer 1, and reduces The effect of suppressing a decrease in cutting performance such as wear resistance due to chipping and film peeling can be obtained.

  Here, according to the present invention, it is desirable that the second layer 3 is formed by diffusion of an element contained in any one of the base material 6, the first layer 2 and the third layer 4. Since the elements of the first layer 2 and the third layer 4 are contained in the second layer 3 by diffusion, the interlayer adhesion between the second layer 3 and the first layer 2 and between the second layer 3 and the third layer 4 is reduced. It is desirable because it improves the film peeling resistance. Further, the inclusion of the elements W and Co in the base material 6 improves the interlayer adhesion and toughness of the second layer 3, which is also desirable in that the fracture resistance and chipping resistance are improved.

  In addition, since the second layer 3 is intermittently present, the residual stress applied to the hard coating layer 1 can be optimized, and thus it is desirable in that the peeling or the loss of the film due to the residual stress can be prevented. Here, being intermittently present means a state in which intermittent portions 10 are scattered in the second layer 3 as shown in FIG. Further, when it is assumed that the second layer 3 exists continuously and uniformly (when it is assumed that the corners of the intermittent portions are connected linearly), the average film thickness of the second layer 3 is 0. It is preferable that the thickness is from 0.5 to 4 μm, because the adhesion between the first layer 2 and the third layer 4 can be improved, and a decrease in the adhesion due to a thick film can be prevented.

As shown in FIG. 4, in the Auger electron spectroscopic analysis data of the second layer 3, the peak intensity of Al near 1400 eV, the peak intensity of W near 1750 eV, and the peak intensity of Co near 800 eV are I _Al , _Assuming that I _W and I _Co are I _W / I _Al ratios of 0.1 to 0.5 and I _Co / I _Al ratios of 0.1 to 0.5, W and Co are excessive. This is desirable because it can prevent the metal from being diffused into the metal and becoming a source of destruction, and can improve the fracture resistance.

  Further, the aluminum oxide of the third layer 4 occupies 50% by weight or more of the κ-type crystal or the κ-type crystal, and the remainder is a mixed crystal composed of the α-type crystal. The cutting is desirable in that the interlayer adhesion with the second layer 3 can be further improved, thereby improving the film peeling resistance of the third layer 4 made of aluminum oxide. These crystal structures can be measured by a general X-ray diffraction method (not shown). Here, the third layer 4 made of aluminum oxide contains compounds such as carbides, oxides, nitrides, carbonitrides, carbonates, and carbonitrides of Ti due to diffusion at the time of heat treatment described later. May be.

  Further, it is desirable that the uppermost layer 8 of the first layer 2 be made of titanium carbonitride composed of streak-like particles because fracture resistance can be improved without deteriorating wear resistance. Further, when the average thickness of the titanium carbonitride layer is 0.5 to 15 μm, particularly 4 to 8 μm, the toughness of the third layer 4 can be improved, and the adhesion is reduced due to the increase in thickness. It is desirable because it can prevent.

  Further, as shown in FIG. 3, including an underlayer 7 made of granular titanium nitride as the first layer improves the interlayer adhesion between the base material 6 and the first layer 2, and improves the first layer 2 and the first layer 2. Due to the synergistic effect with the effect of improving the interlayer adhesion of the three layers 4, it is desirable to improve the film peeling resistance and chipping resistance in high-load cutting such as black scale cutting of cast iron. Further, since the amount of WC and Co diffusion from the base material can be adjusted by titanium nitride, the thickness of the second layer 3 can be controlled, and the hard coating layer due to excessive WC and Co diffusion. 1 can be prevented from decreasing.

  When the average thickness of the underlayer 7 is 0.5 to 3.0 μm, the adhesion of the third layer 4 can be improved, and the film peeling resistance and chipping resistance can be improved, and This is desirable because it is possible to prevent a decrease in adhesive force due to the increase in thickness.

  Further, the fact that the concentration of W and Co in the extreme surface of the tungsten carbide-based cemented carbide base material 6, particularly in the depth range of 0.05 to 3 μm from the surface to the inside, is higher than that in the inside, It is desirable because the impact generated at the time of the above can be absorbed and the fracture resistance of the hard coating layer 1 can be improved.

  Further, the concentration of W and Co contained in the second layer 3 is more than twice as high as the concentration of W and Co contained in the first layer 2 and the third layer 4, preferably, , WC and Co are not detected in the first layer 2 and the third layer 4 at 1% by weight or less, particularly 0.5% by weight or less, and are detected only in the second layer. It is desirable because the adhesion between the three layers can be increased and the wear resistance of the hard coating layer 1 can be prevented from lowering.

  It is desirable that TiN be applied as the outermost layer 5 of the hard coating layer 1. This is because TiN has a golden color, so that the TiN wears after cutting, and the color of the worn portion is no longer gold, so that it is possible to determine whether the surface-coated cutting tool 1 is used. .

(Production method)
In order to manufacture the above-mentioned surface-coated cutting tool, first, WC and a metal carbide, nitride, carbonitride or the like of the 4a, 5a, 6a group, which can be formed by firing the above-mentioned tungsten carbide-based cemented carbide base material Co and other metal powders, carbon powders, etc. are appropriately added to and mixed with the inorganic powder, and molded into a predetermined tool shape by a known molding method such as press molding, cast molding, extrusion molding, or cold isostatic pressing. Then, by firing in a vacuum or in a non-oxidizing atmosphere, the above-described tungsten carbide-based cemented carbide base material is produced.

  After the base material is polished as required, a hard coating layer is formed on the surface by a chemical vapor deposition method. The film forming conditions for each layer are shown below.

For example, a nitride of titanium, carbide, carbonitride, the first layer 2 forming a film composed of a single layer and or layers of carbon nitride, 0.1～10Vol the TiCl ₄ gas in volume percent as a reaction gas composition %, 0~60vol% _{N 2} gas, 0～0.1Vol% of CH ₄ gas, 0～0.1Vol% of _CH 3 CN gas, 0～0.1Vol% CO ₂ gas, and the remainder _{H 2} gas Is sequentially adjusted and introduced into the reaction chamber, and the inside of the chamber is formed at 800 to 1100 ° C. and 5 to 85 kPa to form a film.

Among them, the conditions for forming the stripe-shaped TiCN layer, as a reaction gas composition, 0.1～10Vol% of TiCl ₄ gas by volume%, 0~60vol% _{N 2} gas, a CH ₄ gas 0-0 1 vol%, CH ₃ CN gas is 0 to 0.1 vol%, and the remainder is H ₂ gas. The mixed gas is sequentially adjusted and introduced into the reaction chamber, and the chamber is set at 700 to 900 ° C. and 5 to 85 kPa. Film.

Subsequently, for forming the third layer 4 made of aluminum oxide, ₃ to 20 vol% of AlCl ₃ gas, 0.5 to 3.5 vol% of HCl gas, 0 to 0.01 vol% of H ₂ S gas, and A film is formed at 900 to 1100 ° C. and 5 to 10 kPa using a mixed gas of H ₂ gas.

  According to the present invention, after the first layer 2 and the third layer 4 are sequentially formed, the treatment temperature is maintained at 850 to 1100 ° C. for 1 to 10 hours in a hydrogen and / or nitrogen atmosphere of 1 to 40 kPa. A major feature is that heat treatment is performed, whereby the second layer 3 can be formed by diffusion from the base material 6, the first layer 2, and the third layer 3.

Then, if necessary, a TiN film is formed as the outermost layer 5 for use corner identification. The TiN layer, which is the outermost layer 5, is formed by using a mixed gas of TiCl ₄ gas of 0.1 to 10 vol%, N ₂ gas of 20 to 60 vol% and H ₂ gas at 800 to 1100 ° C. The outermost TiN layer is coated under the condition of 50 to 90 kPa.

The film thickness of each layer can be controlled by the film formation time and the like in addition to the above conditions.

  8.0% by weight of metal cobalt (Co) powder having an average particle diameter of 1.2 μm, 0.7% by weight of tantalum carbide (TaC) having an average particle diameter of 2.0 μm, 0.6% by weight of titanium carbide, and niobium carbide Was formed into a cutting tool shape (CNMA120412) by press-molding a mixed powder composed of tungsten carbide (WC) powder having a mean particle size of 1.5 μm and a balance of 0.4% by weight. The temperature was raised from 1000 ° C. or higher at a rate of 3 ° C./min, and calcined at 1500 ° C. for 1 hour in a vacuum of 0.01 Pa to produce a tungsten carbide-based cemented carbide base material.

  A cutting tool comprising a hard coating layer having the configuration shown in Table 1 was produced on the surface of the obtained tungsten carbide-based cemented carbide base material by a CVD method.

In the method of forming the hard coating layer, the first layer and the outermost layer of TiN use a mixed gas composed of 5% by volume of TiCl ₄ gas, 45% by volume of N ₂ gas, and H ₂ gas at 1000 ° C. And 70 kPa.

The first layer of TiC was formed by using a mixed gas composed of 5% by volume of TiCl ₄ gas, 0.05% by volume of CH ₄ gas, and H ₂ gas in the atmosphere of 1000 ° C. and 70 kPa.

The first layer of TiCN is composed of 5% by volume of TiCl ₄ gas, 40% by volume of N ₂ gas, 0.05% by volume of CH ₄ gas, 0.07% by volume of CH ₃ CN gas, and the rest from H ₂ gas. A mixed gas was formed at 800 ° C. in an atmosphere of 65 kPa.

Al ₂ O ₃ of the third layer is composed of 10% by volume of AlCl ₃ gas, 1.5% by volume of HCl gas, 1.5% by volume of CO ₂ gas, 0.01% by volume of H ₂ S gas, and Using a mixed gas of H ₂ gas, a film was formed at 1000 ° C. in an atmosphere of 7 kPa.

  Further, in Samples Nos. 1 to 5, after forming the third layer made of aluminum oxide, a heat treatment was performed under the conditions shown in Table 2 to produce a second layer.

  In Sample No. 7, after the first layer made of the titanium compound was formed, heat treatment was performed for 2 hours in a furnace at a temperature of 1000 ° C., a pressure of 20 kPa, and a hydrogen atmosphere.

With respect to the obtained surface-coated cutting tool, the fracture surface of the hard coating layer was observed with a scanning electron microscope, and the thickness of each layer was measured. The apparatus used was a scanning electron microscope of Hitachi S800. The composition of the second layer was measured at the fractured surface by Auger electron spectroscopy (point A in FIG. 2). An example of this analysis result is shown in FIG. Table 1 shows the peak intensity ratio of Ti at 400 eV with respect to the peak intensity of Al at around 1400 eV. Further, when the peak intensity of Al near 1400 eV, the peak intensity of W near 1750 eV, and the peak intensity of Co near 800 eV measured by Auger electron spectroscopy are I _Al , I _W , and I _Co , The ratio of _IW / _IAl was calculated and is shown in Table 1. The apparatus used for Auger electron spectroscopy here is a scanning FE-Auger electron spectrometer of Model 680 manufactured by PHI. The crystal structure of the aluminum oxide layer was measured using a general X-ray diffraction analysis. Table 1 shows the results. The apparatus used for the X-ray diffraction analysis is RINT1100 manufactured by Rigaku Denki.

  Further, as a result of analyzing the W and Co concentrations of the cross section of the sample by EDS analysis, the sample No. In Nos. 1 to 5, the W and Co concentrations near the extreme surface of the base material were high, and the W and Co concentrations in the second layer were more than twice as high as those in the first and third layers. On the other hand, the sample No. In 6 and 7, W and Co were not detected in the hard layer. In Sample No. 7 to which heat treatment was applied after forming the first layer, W and Co were detected in the first layer without generation of the second layer.

  Using this cutting tool, cast iron was cut under the following conditions, the cutting edge of the cutting tool was observed, and the flank wear was measured. The cutting time when the flank wear amount reached 0.2 mm during the cutting test was measured. Further, a chipping resistance test and a film peeling resistance test were performed by cutting a cast with black scale, and the ratio of the number of corners at which chipping and peeling were evaluated when 20 corners were evaluated. The closer to 0, the better performance, and the closer to 100, the worse performance. These results are shown in Table 1.

(Abrasion resistance test)
Work material: Cast iron with black skin (FC250)
Tool shape: CNMA120412
Cutting speed: 350 m / min Feeding speed: 0.4 mm / rev
Cut: 1.0mm
Others: Uses solution-based water-soluble cutting fluid (chipping resistance test)
Work material: Cast iron with black skin (FC250)
Tool shape: CNMA120412
Cutting speed: 350 m / min Feeding speed: 0.4 mm / rev
Cut: 1.0mm
Others: Uses solution-based water-soluble cutting fluid (Film resistance peeling test)
Work material: Cast iron with black skin (FC250)
Tool shape: CNMA120412
Cutting speed: 350 m / min Feeding speed: 0.3 mm / rev
Cut: 4.0mm
Others: Uses solution-based water-soluble cutting fluid

  From Table 1, it can be seen that Sample No. provided with the second layer containing Al, Ti, W, and Co was provided. In Examples 1 to 5, both the peeling resistance and the chipping resistance in the cutting test were good, and excellent wear resistance was exhibited.

  On the other hand, in Sample No. 6 in which the second layer was not provided, all of the abrasion resistance, peeling resistance and chipping resistance were poor.

  Further, in Sample No. 7, which was subjected to heat treatment after forming the first layer made of the titanium compound, film peeling, particularly peeling of the aluminum oxide layer, occurred, and both chipping resistance and wear resistance were not satisfactory. Was.

It is a conceptual diagram showing an example about the structure of the hard coating film of the surface coating cutting tool in this invention. It is a schematic diagram about the 2nd layer vicinity of the surface coating cutting tool in this invention. FIG. 2 is a schematic view of the vicinity of a base material interface (base layer) of the surface-coated cutting tool according to the present invention. It is an Auger electron spectroscopic analysis result in the second layer (point A) of the surface-coated cutting tool (FIG. 2) of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Hard coating layer 2 1st layer 3 2nd layer 4 3rd layer 5 Outermost layer 6 Base material 7 Bottom layer 8 Top layer 9 Intermittent part I Aluminum peak value by _Al Auger electron spectroscopy I Tungsten by _W Auger electron spectroscopy I Peak value of cobalt by _Co Auger electron spectroscopy A Points analyzed by Auger electron spectroscopy

Claims (12)

On the surface of the tungsten carbide-based cemented carbide base material, a first layer consisting of a single layer or multiple layers of titanium nitride, carbide, carbonitride, and carbonitride, and at least titanium (Ti), aluminum (Al) A surface-coated cutting tool, comprising: a hard coating layer formed by sequentially forming a second layer mainly containing tungsten (W) and cobalt (Co), and a third layer made of aluminum oxide. The surface-coated cutting tool according to claim 1, wherein the second layer is formed by diffusing any of the elements in the base material, the first layer, and the third layer. . The average thickness of the second layer is 0.05 to 4 [mu] m assuming that the second layer is intermittent and the second layer is continuous and uniform. Surface coated cutting tools. In the Auger electron spectroscopy data of the second layer, when Al peak intensity around 1400 eV, W peak intensity around 1750 eV, and Co peak intensity around 800 eV are I _Al , I _W , and I _Co , respectively. 4. The surface-coated cutting tool according to claim 1, wherein I _W / I _Al = 0.1 to 0.5 and I _Co / I _Al = 0.1 to 0.5. 5. The surface-coated cutting tool according to any one of claims 1 to 4, wherein an uppermost layer of the first layer is formed of a streaky titanium carbonitride layer. The surface-coated cutting tool according to claim 5, wherein the average thickness of the striped titanium carbonitride layer is 0.5 to 15 m. 7. The surface-coated cutting tool according to claim 5, wherein a lowermost layer of the first layer is formed of a granular titanium nitride layer. The surface-coated cutting tool according to claim 7, wherein the titanium nitride layer has an average thickness of 0.5 to 3 m. 6. The aluminum oxide of the third layer, wherein the κ-type crystal or the κ-type crystal occupies 50% by weight or more, and the remainder comprises a mixed crystal composed of an α-type crystal. Surface coated cutting tools. The surface-coated cutting tool according to any one of claims 1 to 9, wherein the concentration of W and Co on the extreme surface of the tungsten carbide-based cemented carbide base material is higher than that inside the base material. . The surface according to claim 1 or 2, wherein the W and Co concentrations in the second layer are twice or more higher than the W and Co concentrations in the first layer and the third layer. Coated cutting tools. On the surface of the tungsten carbide-based cemented carbide base material, the first layer consisting of a single layer or multiple layers of titanium nitride, carbide, carbonitride, and carbonitride, and the third layer consisting of aluminum oxide After the layers are sequentially formed, a heat treatment is performed at a processing temperature of 850 to 1100 ° C. for 1 to 10 hours in a hydrogen and / or nitrogen atmosphere of 1.3 to 40 kPa, and the first layer and the third layer are heated. A method for producing a surface-coated cutting tool, wherein a second layer mainly containing titanium (Ti), aluminum (Al), tungsten (W) and cobalt (Co) is formed therebetween.

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