KR100334709B1 - Titanium carbide nitride-based cermet cutting edges and coated cermet cutting edges - Google Patents

Abstract

The present invention represents a cermetized cutting edge made of titanium carbide nitride and a cutting edge made of coated cermet, and is typically composed of a metal bond containing Co and Ni.

Monostructure hard phase containing at least one metal component belonging to groups 4a, 5a and 6a of the periodic table, bistructured rigid phase containing a core portion and a shell portion completely surrounding the core portion, wherein the core portion comprises at least one Ti component The shell portion contains at least one component of Ti and a metal component belonging to groups 4a, 5a and 6a of the periodic table other than Ti. The bistructured hard phase with the core part and the shell part discontinuously distributed around the core part, and the latter bistructured hard phase occupy more than 30% of the area, and the cutting edge significantly prevents fracture resistance.

Description

Titanium carbide-based cermet cutting edges and cutting edges of coated cermets

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting edge (cermet cutting edge) made of cermet, and more particularly to a titanium carbide nitride based cermet cutting edge exhibiting excellent cleavage resistance.

In the early days when a cermet cutting edge was invented, TiC-Mo-Ni alloy was used as a cermet. However, the alloys have high wear resistance but low toughness, which limits the use of cermet cutting edges in high speed finishing cutting of steel. Subsequently, it has been found that the addition of nitrides such as TiN has a significant impact on improving the toughness of the cermet mixture. Such cutting edges of cermet mixtures have been used for milling, as well as for cutting of steel, because of the inherent advantages of cermet: high wear resistance and high quality surface finish.

On the other hand, on cutting edges consisting of mixed carbide components, coated carbides have been developed. Coated carbide contains a mixed carbide component as a substrate and is made by coating a surface of the substrate with a hard compound such as TiC, Ti (C, N), Al ₂ O ₃ . Such coated cutting edges exhibit improved wear resistance without losing toughness as an inherent property of the bonded carbide component. Under these conditions, there is a need for a cermet with more improved toughness while maintaining wear resistance.

In general, cermets have a hard core / shell (core / rim) structure in which a small amount of particles such as Ti (C, N) are surrounded by a carbonitride solid solution such as (Ti, Mo) (C, N). It has a hard phase structure. Many studies have been conducted to improve the toughness of cermets based on the inherent characteristics of cermets. For example, US Pat. No. 4,778,521 discloses a core of Ti (C, N), an intermediate layer rich in WC surrounding the core, and an outer layer of (Ti, W) (C, N) surrounding the intermediate layer. A three-layer core / shell structure is disclosed. European Patent Publication No. 0,406,201 B1 also discloses a cermet having at least two core / shell structures in a hard phase. In addition, European Patent Publication No. 0,578,031 A2 discloses a cermet in which a Ti-rich hard phase is dispersed in a matrix of a conventional core / shell structure.

Since the conventional cermet structure is based on the conventional cermet structure structure in which the shell of solid solution carbonitride surrounds the core of Ti or Ti-rich hard particles, even if some personality is achieved, the toughness is not sufficiently improved. In addition, there have been attempts to increase the content of binder metals such as cobalt and nickel in order to improve toughness. In this case, however, a problem arises in that wear resistance and plasticity-deformation are reduced.

In addition, since Ti, which is a main component forming the hard phase of cermet, has a property of easily reacting with nitrogen, it is possible to form a cured layer on the surface by controlling the nitrogen partial pressure in a sintering atmosphere. In fact, Japanese Patent Laid-Open No. 2-15139 discloses a cermet in which the wear resistance of the cermet surface portion is improved by the above method. However, even in this case, since the structure of the cermet has a core / shell structure as described above, room for improvement remains in terms of toughness.

The present invention aims to solve the above problems.

1 is a schematic diagram showing the overall spacing of the cermet cutting blades of Example 7 observed with an electron microscope.

Fig. 2 is a schematic diagram showing the total spacing of the cermet cutting blades of Comparative Example 7 observed with an electron microscope.

Figure 3 is a schematic diagram showing the entire interval of the cermet cutting blade of Example 14 observed with an electron microscope.

Figure 4 is a schematic diagram showing the entire interval of the cermet cutting blade of Comparative Example 14 observed with an electron microscope.

Features of the present invention are as follows.

As a titanium carbonitride based cermet cutting edge;

3 to 20% by weight of a metal-bonded phase composed mainly of Co and Ni,

3 to 30% by weight of a hard phase of a single structure consisting of carbides, nitrides and at least one component selected from the group consisting of metal compounds belonging to groups 4a, 5a and 6a of the periodic table and solid solutions composed of at least two or more of the compounds Contains,

A titanium carbonitride-based cermet cutting edge having a balance between a hard phase of a dual structure constituting a core portion and a shell portion completely surrounding the core portion,

Titanium carbonitride and / or a core portion consisting of at least one carbonaceous nitride of raw water M selected from one of the metal elements belonging to the periodic table 4a, 5a, 6a excluding Ti and Ti, and the periodic table 4a, 5a, excluding Ti and Ti Titanium carbonitride-based cermet cutting edge composed of a shell portion consisting of at least one element M carbonitride selected from one of the metal elements belonging to 6a, wherein the shell portion has a low Ti concentration and a high M concentration compared to the core portion To

Part or all of the dual structure hard phase is replaced with a discontinuous dual structure hard phase consisting of a core portion and a shell portion such that the shell portion is discontinuously distributed around the core portion, thereby partially exposing the core portion to the metal bond,

The discontinuous dual-structure hard phase is characterized by having excellent durability against damage by being configured to occupy 30% or more of the total surface area of the cermet when analyzed by electron microscope structure analysis.

According to another aspect of the present invention, in the coated cermet cutting edge configured as described above, the cermet is selected from titanium carbide, titanium nitride, titanium carbonitride, titanium carbonate-nitride, (Ti, Al) N and aluminum oxide. At least one compound is characterized in that it is coated with a thickness of 0.5 to 20㎛.

In the cermet cutting edge or coated cermet cutting edge according to the present invention described above, when hardness is measured inward from the outermost surface to the Vickers strength, a peak having a higher hardness than the inner portion is present within a depth of 50 μm at the outermost surface. It contains a hardening area | region.

Further, in the cermet cutting edge or coated cermet cutting edge according to the present invention, the average particle size of the hard phase is preferably in the range of 0.1 to 1.5 mu m, more preferably 0.5 to 1.2 mu m.

In addition, in the coated cermet cutting edge according to the present invention, the coating comprises a (Ti, Al) N layer with a thickness of 0.5 to 5 μm, and is carried out by the PVD method, or a TiCN coating layer having a thickness of 0.5 to 5 μm. And coated by MT-CVD to grow particles of TiCN as longitudinal crystals in a direction perpendicular to the cermet surface.

The inventors of the present invention conducted a study on improving the toughness of a cermet used as a cutting edge while paying attention to the core / shell structure employed in the prior art.

Generally, Ti compounds are mixed to improve the abrasion resistance of the cermet. The Ti mixture is present in the cermet as the core of the hard phase, ie as the core of Ti (C, N) or Ti rich carbonitride solid solution particles. Each core is also surrounded by a shell, i.e., a carbonitride solid solution having a lower Ti concentration than the particles. Although the crystal grains of the core particles and the shell are both NaCl type, these particles have different coefficients of thermal expansion due to differences in constituents. Since the thermal stress mode depends on the content of the core and the rim, it is not possible to uniformly determine the tensile stresses acting on the core and the shell, but it contains more Ti compared to the rim containing more W and Mo. It is thought that the effect of the tensile stress on the core. As in the case of the core and the shell, the particles having a NaCl-type crystal structure do not exhibit a sliding deformation unlike the particles having a WC-type crystal structure. Therefore, the phase composed of the particles is easily broken or broken by the tensile stress. Therefore, the reduction of thermal stress in the core / shell structure is a very important factor for strengthening the cermet toughness. Japanese Patent Application Laid-open No. Hei 6-248385 discloses a cermet including a Ti (C, N) particle phase having a single structure, that is, having a non-core / shell structure. However, in the cermet, the content of the phase is as low as 1 to 5% by volume, and the thermal stress is not sufficiently reduced because most of the phases constituting the cermet are conventional core / shell structure types. In addition, even if it is possible to increase the content of the single structure of the Ti (C, N) particles, since the parts forming the particles are low in hardness, the bonding strength between the Ti (C, N) particles and the metal bonding phase is small The wear strength is reduced.

Under these conditions, the inventors of the present invention have come up with the following idea. Thermal stresses derived from conventional core / shell structures render the core / shell structures incomplete, ie, rigid particles of Ti (C, N) or Ti-rich complex metal carbonitrides (these particles Cores) are brought into contact with particles having relatively low Ti content (these particles correspond to shells in a conventional core / shell structure), or are Ti (C, N) or Ti-rich composite metals Hard particles of carbonitride can be reduced by incompletely enclosing them with relatively small Ti content, thereby exposing some of the hard particles.

That is, the inventors of the present invention came to think of a cermet structure in which a part of the core is exposed on the metal bond and the shell is discontinuously distributed around the core.

The structure can actually be achieved as follows. First, Ti (C, N) made directly from the oxide of Ti is used as a raw material, and the sintering is stopped before the core / shell structure is sufficiently developed in the sintering process of the mixed powder of the raw materials. By performing a cutting test on the thus obtained cermet, it was found that the cermet having the above structure exhibited an unexpected improvement in wear resistance and toughness.

The present invention has been made in accordance with the above findings. Generally, the cermet of the present invention is composed of a metal bonded phase, a hard structure of a single structure, a hard structure of a dual structure completely surrounded by a shell portion of a core portion, a core portion, and a shell portion discontinuously distributed around the core portion. It consists of a solid phase of a dual structure.

Co and / or Ni are usually used as the main constituents of the cermet metal bond phase. When these components are used at less than 3% by weight, the cermet becomes brittle because the amount of metal bonding phase which gives the toughness of the cermet is too small. Moreover, when it exceeds 20 weight%, hardness becomes so low that it cannot use as a cutting edge. Therefore, the content of Co and / or Ni in the cermet of the present invention is 3 to 20% by weight.

In addition, in the cermet according to the present invention, the content of the metal carbonitride constituting the hard phase having a single structure is specified to be 3 to 30% by weight. If it is less than 3% by weight, the effect of improving the desired wear resistance cannot be achieved, and more than 30% by weight deteriorates the damage resistance of the cermet.

Among the dual structured hard phases of the cermet of the present invention, the hard phases in which the shell is discontinuously distributed in the core portion should occupy at least 30% of the total surface area of the cermet. If the ratio is less than 30%, the effect of reducing the thermal stress derived from the core / shell structure cannot be sufficiently obtained. If the cermet is used as a cutting edge, the phase in the mixture will collapse during the cutting process. In other words, the above-mentioned ratio cannot significantly improve the damage resistance of the cermet.

As described above, by controlling the sintering atmosphere, it is possible to form a cermet having a small amount of the metal-bonded phase in the vicinity of the surface and a large hard phase content. Thereby, a cermet cutting edge having excellent toughness and abrasion resistance can be provided by using the cermet according to the present invention having the hardened region as described above in the surface portion of the cutting edge having the hardened phase near the surface. The cermet cutting edge can test the cross section of each cutting edge using a micro Vickers hardness meter. As a result, the gradient was observed in the cross section of each cutting edge. Hardness gradient starts at 0.5-1 mm below the surface and gradually increases towards the surface. At each cutting edge, a peak of hardness value that is harder than the inner portion of the cutting edge is present between 50 mu m below the outermost surface. If the ratio of the peak hardness value to the warning value of the inner portion is less than 1.3, desirable wear resistance cannot be obtained. Therefore, the ratio of the peak hardness value to the hardness value of the inner portion of the cutting edge of the present invention is preferably 1.3 to 1.8.

Depending on the manufacturing conditions, there may be a softening band on the outermost surface of the cutting edge consisting of a bonded phase or a hard phase having only a single structure with a metal bonded phase, which has a lower hardness value than the inner portion. The softening zone may coexist with the above-mentioned hardening region at the outermost surface of the cermet cutting edge according to the present invention.

Cermet prepared by coating Ti carbide, nitride, carbonitride, carbonitride (hereinafter referred to as Ti compound), Ti (C, N), aluminum oxide, etc. on the surface of the cermet as a base material by CVD or PVD It is often used as a substrate of the cutting edge, when the coated cutting edge is used to improve the toughness and wear resistance according to the present invention is more excellent.

The thickness of the coating layer coated on the surface of the cermet substrate is preferably 0.5 to 20 µm.

In the PVD method, since the deposition rate is relatively slow, if the coating becomes too thick, it is easily dropped by the residual stress of the coating layer. Therefore, the thickness of the coating layer produced by the PVD method should be about 0.5 to 15 mu m, preferably about 1 to 10 mu m.

Since the (Ti, Al) N coating produced by the PVD method has high heat conduction heat, excellent thermal shock resistance can be obtained by coating (Ti, Al) N using the cermet of the present invention having high toughness and excellent wear resistance as a substrate.

When the substrate of cermet is coated with Ti compound or aluminum oxide by CVD method, especially under high temperature coating (that is, using HT-CVD method), the substrate has high wettability with TiC or Ti (C, N). By coating with), the components of the metal bonding phase, especially Ni, are dispersed in the coating layer to lower the abrasion resistance of the coated product. For this reason, when using the CVD method, the substrate of the cermet is preferably coated at a low temperature. That is, it is preferable to use the MT-CVD method which can coat | substrate a substrate with Ti (C, N) at the temperature below 1000 degreeC. This inhibits the diffusion of components of the metal bond phase into the coating layer.

In addition, the following coating method may be used. First, TiN having low abundance and components of the metal-bonded phase are coated by HT-CVD method. If a coating layer is formed, Ti (C, N) is coated by MT-CVD method, and then aluminum oxide or the like is deposited thereon. Form.

The Ti (C, N) coating layer formed by the MT-CVD method can be a thick layer so that the vertical crystals can be grown vertically with respect to the surface of the base material without lowering the strength of the cutting surface of the cutting edge made thereby. . This greatly improves the wear resistance of the product. The effect of the coating can be further improved by using a cermet according to the present invention excellent in toughness and wear resistance as a base material.

In addition, by combining with the PVD method, it is also possible to coat a cermet with a compound such as (Ti, Al) N, which is difficult to coat by the CVD method. That is, first, a coating film of (Ti, Al) N or the like is formed by the PVD method on the coating film formed by the CVD method.

In the cermet cutting edge and the coated cermet cutting edge according to the present invention, the cermet as the base material is a titanium carbonitride-based cermet mainly composed of titanium, and the hard phases all have a NaCl type crystal structure.

The hard phase, which is mainly composed of titanium, is generally brittle because it is hard, and when the particle size of the hard phase exceeds 1.5 µm, it is easily broken by concentration of stress. On the other hand, when the particle size is smaller than 0.1 mu m, the wear resistance of the hard phase is lowered, cracking due to abrasion tends to be large, and plastic deformation is likely to occur. For this reason, the particle size of the hard phase should be 0.1 to 1.5 mu m, preferably 0.5 to 1.2 mu m.

When the content of metal element M belonging to groups 4a, 5a, and 6a in the periodic table as a metal element other than titanium exceeds 50% by weight, the wear resistance of the cermet is lowered because the content of Ti, which is an active ingredient for improving the hardness of the cermet, is relatively low. . Therefore, the content of M should be less than 50% by weight.

If the nitrogen content in the titanium nitride-based cermet is increased, the content of M present as a solid solution in the metal-bonded phase is increased to strengthen the solid-phase. Nitrogen also improves toughness of hard phases, and hard phase particles inhibit grain growth during sintering. The nitrogen content calculated from the formula N / (C + N) expressed in molar units is preferably 0.1 to 0.6.

If the content represented by the above formula is 0.1 or less, the above-mentioned desirable effect cannot be obtained. If the content exceeds 0.6, the degree of sintering decreases and voids remain in the cermet.

Example 1

Each of the cermet cutting edges according to Examples 1 to 10 and Comparative Examples 1 to 10 according to the present invention was made as follows.

As a raw material, the following powder is prepared. Each powder has a predetermined average size in the range of 0.5 to 2 mu m.

Ti (C, N) powder (weight ratio C / N = 50/50), TiN powder,

TaC powder, NbC powder, WC powder, Mo ₂ C powder, VC powder, ZrC powder, Cr ₃ C ₂ powder,

(Ti, W, Mo) (C, N) powder (Ti / W / Mo = 70/20/10, C / N = 70/30)

(Ti, Ta, V) (C, N) powder (Ti / Ta / V = 70/20/10, C / N = 60/40)

(Ti, Nb, Mo) (C, N) powder (Ti / Nb / Mo = 80/10/10, C / N = 50/50), Co powder, Ni powder, powder C of graphite.

The powders were mixed according to the formula in Table 1, and each mixture was wet mixed for 24 hours and dried. Press-molded at a pressure of 1 t / cm 3 to prepare green compact A-J.

The prepared green compacts A to J were sintered according to the following sintering conditions. First, it heated up at the temperature increase rate of 2 degree-C / min from room temperature to 1300 degreeC in the vacuum of 0.05torr. The atmosphere was changed to a nitrogen atmosphere of 10 torr or less, and the temperature was raised to a predetermined firing temperature within the range of 1380 ° C to 1460 ° C at the same temperature rising rate. When the sintering temperature reached a predetermined temperature, the atmosphere was changed to a vacuum atmosphere at a predetermined pressure within a range of 0.5 to 30 torr and maintained for 60 minutes. The furnace was then cooled in the same atmosphere. By sintering under the sintering conditions as described above to prepare 10 cermet cutting blade EX1-10 according to the present invention. Each cermet cutting edge has a cutting insert of ISO standard CNMG 120408.

For comparison, the green compacts A to J were sintered under the same conditions as those described above except that the sintering temperature was set at a relatively high temperature of 1530 ° C. to 1560 ° C. to produce a comparative cermet cutting tool CE1-CE10.

In addition, the sequential strength from the outermost surface to the inside of the cutting section of each cermet was measured by Vickers hardness, and the peak depth of the Vickers hardness was measured. In addition, by observing the inside of the cross section with an electron microscope, the structure and ratio of the hard phase was measured using an image analyzer.

In addition, the average particle size of the hard phase was measured by image analysis.

1 and 2 are schematic diagrams showing the internal structure of the cermet cutting edge EX7 and CE7.

The numbers in these figures represent the following.

1: Metal-bonded phase composed mainly of Co and / or Ni

2: solid phase of dual structure

More specifically, 2a represents a core portion composed of carbonitride and / or titanium carbonitride consisting of at least one element M selected from metal elements belonging to the Group 4a, 5a, and 6a metals except for Ti and Ti, and 2b represents When composed of (Ti, M) -carbonitride, the content of Ti shows a smaller shell portion than the core portion.

3: a monolithic solid phase composed of at least one compound selected from carbides, nitrides and carbonitrides of metal elements belonging to the periodic tables 4a, 5a and 6a

In addition, in order to measure the damage resistance of each cermet cutting blade made as described above, the side wear area of the cutting surface subjected to wet interrupted cutting under the following conditions was measured.

Steel to be cut: Round bars of JIS S20C, DIN CK22 and ANSI 1020 standards, with four longitudinal grooves in the longitudinal direction at regular intervals.

Cutting speed: 250m / min,

Feed rate: 0.2㎜ / rev,

Cutting depth: 2㎜,

Cutting time: 20 minutes

The results are shown in Tables 2 and 3.

From the above results, the cermet cutting edge (EX1-EX10) of the present invention confirms that more than 30% of the area consists of a hard structure of a dual structure in which the shell portion is discontinuously divided. In addition, it was confirmed that the cermet cutting edges CE1-CE10 of the comparative example, that is, the conventional cutting edges, were all composed of a solid phase of a single structure and / or a structure in which the shell portion completely surrounded the periphery of the core portion.

As is apparent from Tables 2 and 3 above, the cermet cutting edge of the present invention has superior damage resistance as compared to the conventional cermet cutting edge.

Example 2

A part of the green compact AJ prepared in Example 1 was heated at a temperature increase rate of 2 ° C / min in a vacuum atmosphere of 0.05 torr from sintering conditions, that is, from room temperature to 1300 ° C, and then heated to 1300 ° C. It was changed to a room temperature atmosphere of 5 torr, and the temperature was raised to a predetermined sintering temperature in the range of 1400 ° C to 1460 ° C at the same heating rate, and the atmosphere was changed to a vacuum atmosphere of a predetermined pressure within the range of 0.01 to 0.1 torr and maintained for 60 minutes. The furnace was then cooled in the same vacuum atmosphere to obtain a cermet cutting edge with a cutting insert having the specification of ISO CNMG 120408.

For comparison, a part of the green compacts A to J having the same composition as in Table 1 is set at a relatively high sintering temperature, that is, a predetermined temperature within the range of 1530 ° C. to 1560 ° C., and the atmosphere is a nitrogen atmosphere having a predetermined pressure within the range of 5 to 15 torr. A cerme cutting edge CE11-CE16 of a comparative example was obtained in the same manner as in the above sintering conditions.

In addition, the sequential strength from the outermost surface to the inside of the cutting section of each cermet was measured by Vickers hardness, and the peak depth of Vickers hardness was measured. Also, the inside of the cross section was observed with an electron microscope, and the structure and ratio of the hard phase were measured using an image analyzer.

In addition, the average particle size of the hard phase was measured by image analysis.

3 and 4 are schematic diagrams showing the internal structure of the cermet cutting edge EX14 and CE14.

In addition, in order to measure the damage resistance of each cermet cutting blade made as described above, the side wear area of the cutting surface subjected to wet interrupted cutting under the following conditions was measured.

Steel to be cut: Round rods of JIS S20C, DIN CK22, and ANSI 1020 standards with four longitudinal grooves in the longitudinal direction at regular intervals.

Cutting speed: 300 m / min,

Feed rate: 0.2 mm / rev,

Depth of cut: 2 mm

Cutting time: 20 minutes

The results are shown in Table 4 and Table 5.

From the above results, the cermet cutting edge (EX11-EX16) of the present invention confirmed that more than 30% of the area consists of a hard structure of a dual structure in which the shell portion is discontinuously distributed. In addition, it was confirmed that the cermet cutting edge CE11-CE16 of the comparative example, that is, the conventional cutting edge, is composed of a solid phase of a single structure and / or a structure in which the shell portion completely surrounds the periphery of the core portion.

As is apparent from Tables 4 and 5 above, the cermet cutting edge of the present invention has superior damage resistance compared to conventional cermet cutting edges.

Example 3

The cermet cutting edge EX1-EX10 according to the present invention prepared in Example 1 as a substrate was prepared, and some of these were used as substrates and coated according to the method shown in Table 6, and the coated cermet cutting edge according to the present invention (EXc1 -EXc1) was prepared. Each cutting edge has a coating composition and average thickness as shown in Table 6.

The coating conditions are as follows when the physical ion deposition apparatus, an arc ion plating apparatus, is used.

Coating material: Ti, Ti-Al target, reactive gas (CH ₄ and N ₂ )

Coating Temperature: 700 ℃

Coating Pressure: 2 × 10 ^-2 Torr

Bias Voltage: -200V

When using a chemical vapor deposition apparatus, the coating conditions are as follows.

Coating material: reaction gas (TiCl ₄ , CH ₄ , N ₂ , H ₂ ; however, CH ₃ CN is used instead of CH ₄ when TiCl is deposited)

Coating temperature: 1010 ℃; 890 ℃ when TiCN is deposited

Coating pressure: 100 Torr; 50 Torr when TiCN is deposited

For comparison, cermet cutting edges of CE1 to CE10 were made and some of them were prepared in the same manner as above, and the coated cermet cutting edges CEc1 to CEc12 of Comparative Example were prepared.

In order to measure the damage resistance of each cermet cutting blade made as described above, the side wear area of the cutting surface subjected to wet interrupted cutting was measured under the following conditions.

Steel to be cut: Standard rods of JIS S20C, DIN CK22, and ANST 1020, with four longitudinal grooves in the longitudinal direction at regular intervals.

Cutting speed: 350 m / min,

Feed rate: 0.2 mm / rev.

Depth of cut: 2mm

Cutting time: 20 minutes

The results are shown in Table 6.

* The cutting edge can not work because the time in parentheses has elapsed

** The cutting edge is deactivated after the time in parentheses

Table 6 shows that the coated cermet cutting edges (EXc1 to EXc12) of the present invention consist of a double-structured solid phase in which the shell portion is discontinuously distributed around the core portion, and the surface portion of the double structure is completely enclosed. It has been found that it has significantly higher damage resistance compared to the coated cermet cutting edges of Comparative Examples CEc1 to CEc12 having a hard phase and / or a hard phase of a single structure.

Example 4

The cermet cutting edges EX11 to EX16 according to the present invention prepared in Example 1 were prepared as substrates, and some of them were used as substrates and coated according to the method shown in Table 7 to coated cermet cutting edges according to the present invention. EXc24) was prepared. Each cutting edge has a coating composition and an average thickness as shown in Table 7.

An arc ion plating apparatus or a chemical vapor deposition apparatus, which is a physical vapor deposition apparatus, was used under the same conditions as in Example 3.

For comparison, CE11 to CE106 cermet cutting edges were made and some of them were coated in the same manner as above to prepare coated cermet cutting edges CEc13 to CEc24.

In order to measure the damage resistance of each cermet cutting edge made as described above, the side wear area of the cutting surface subjected to wet interrupted cutting was measured under the following conditions.

Steel to be cut: Standard round rods with four longitudinal grooves in the longitudinal direction at regular intervals.

Cutting speed: 400 m / min.

Feed rate: 0.2 mm / rev.

Depth of cut: 2 mm,

Cutting time: 20 minutes

The results are shown in Table 7.

* The cutting edge can not work because the time in parentheses has elapsed

** The cutting edge is deactivated after the time in parentheses

Table 7 shows that the coated cermet cutting edges EXc13 to EXc24 of the present invention consist of a solid structure of a dual structure in which the shell portion is discontinuously distributed around the core portion, and the surface portion of the double structure is completely enclosed. It has been found that it has significantly higher damage resistance compared to the coated cermet cutting edges of Comparative Examples CEc13-CEc24 having a hard phase and / or a hard phase of a single structure.

As described in Examples 1 to 4, the cermet cutting blade or coated cermet cutting blade according to the present invention retains remarkable damage resistance and is chipped to the cutting surface even in the case of continuous cutting or interrupted cutting under strict cutting conditions. ) Or collapse does not occur. Therefore, the cermet cutting edge or the coated cermet cutting edge according to the present invention exhibits excellent cutting characteristics over a long time, and thus has considerable industrial utility.

Japanese Priority Claim Patent Application No. Hei-266017 and Japanese Patent No. Hei 8-266018, filed July 18, 1996, are incorporated as part of the specification of this application.

Claims (16)

As a titanium carbonitride-based cermet cutting edge, 3 to 20% by weight of a metal bonding phase containing Co and Ni as main components, 3 to 3 solid phases of a single structure comprising at least one component selected from the group consisting of carbides, nitrides and carbonitrides of the metals belonging to groups 4a, 5a and 6a of the periodic table and comprising a solid solution composed of at least two or more of the above compounds. 30% by weight, The remainder consists of a solid phase of a dual structure consisting of a core portion and a shell portion completely surrounding the core portion and inevitable impurities, The core portion is composed of at least one of titanium carbonitride and at least one carbonitride of at least one element M selected from periodic table 4a, 5a, and 6a metals other than Ti and Ti, The shell portion is made of carbonitride of at least one element M selected from the group 4a, 5a, and 6a metals of the periodic table excluding Ti and Ti, and the shell portion has a lower Ti concentration and a concentration of M than the core portion. In the titanium carbonitride-based cermet cutting edge showing a high distribution, The solid phase of the dual structure is partially or wholly substituted with a discontinuous dual solid phase consisting of a core and a shell portion, The shell portion surrounds the core portion discontinuously such that the core portion is exposed on the metal bond, The discontinuous double-hard structure is a cermet cutting edge, characterized in that occupying 30% or more of the total cermet surface area when observed with an electron microscope. As a titanium carbonitride-based cermet cutting edge, 3 to 20% by weight of a metal bonding phase containing Co and Ni as main components, 3 to 3, comprising a solid phase of a single structure comprising at least one component selected from the group consisting of carbides, nitrides and carbonitrides of the metals belonging to groups 4a, 5a and 6a of the periodic table and a solid solution composed of at least two or more of the compounds. 30% by weight, containing The remainder consists of a solid phase of a dual structure consisting of a core portion and a shell portion completely surrounding the core portion and inevitable impurities, The core portion is made of titanium carbonitride and at least one of carbonitride of at least one element M selected from Ti and Ti other than periodic table 4a, 5a, and 6a metals, The shell portion is made of carbonitride of at least one element M selected from the group 4a, 5a, and 6a metals of the periodic table excluding Ti and Ti, and the shell portion has a lower Ti concentration and a concentration of M than the core portion. Has a high distribution, The cutting edge is a titanium carbonitride-based cermet cutting comprising a hardened region in which a peak having a higher hardness than the inner portion is present within a depth of 50 μm at the outermost surface when the hardness is measured inward from the outermost surface to the Vickers hardness. To me, The solid phase of the dual structure is partially or wholly substituted with a discontinuous dual solid phase consisting of a core and a shell portion, The shell portion surrounds the core portion discontinuously such that the core portion is exposed on the metal bond, The discontinuous dual-structure hard phase occupies 30% or more of the total cermet surface area when observed with an electron microscope. As a titanium carbonitride-based cermet cutting edge comprising a coating layer, 3 to 20% by weight of a metal-bonded phase containing Co and Ni as main components, 3-a solid phase of a single structure comprising at least one component selected from the group consisting of carbides, nitrides and carbonitrides of the metals belonging to groups 4a, 5a and 6a of the periodic table and a solid solution composed of at least two or more of the compounds. 30% by weight, The remainder is composed of a dual phase hard phase and inevitable impurities, consisting of a core portion and a shell portion completely surrounding the core portion, The cell portion is made of carbonitride of at least one element M selected from the group 4a, 5a, and 6a metals of the periodic table excluding Ti and Ti, and the shell portion has a lower Ti concentration and a concentration of M than the core portion. Indicates a high distribution, The coating layer consists of at least one compound selected from titanium carbide, titanium nitride, titanium carbide nitride, titanium carbonate-nitride, (Ti, Al) N, and aluminum oxide, and also has carbonitride having a thickness of 0.5-20 μm. In the titanium-based cermet cutting edge, The solid phase of the dual structure is partially or wholly substituted with a discontinuous dual solid phase consisting of a core and a shell portion, The shell portion surrounds the core portion discontinuously such that the core portion is exposed on the metal bond, The discontinuous dual-structure hard phase occupies 30% or more of the total cermet surface area when observed with an electron microscope. As a titanium carbonitride-based cermet cutting edge comprising a coating layer, 3 to 20% by weight of a metal bonding phase containing Co and Ni as a main component, 3-a solid phase of a single structure comprising at least one component selected from the group consisting of carbides, nitrides and carbonitrides of the metals belonging to groups 4a, 5a and 6a of the periodic table and a solid solution composed of at least two or more of the compounds. Contains 30% The remainder consists of a solid phase of a dual structure consisting of a core portion and a shell portion completely surrounding the core portion and inevitable impurities, The core portion is composed of titanium carbonitride and at least one carbonitride of at least one element M selected from the Group 4a, 5a, and 6a metals other than Ti and Ti, and the shell portion has a lower Ti concentration than the core portion. , Distribution of high concentration of M, The cutting edge includes a hardened region in which a peak having a higher hardness than the inner portion is present within a depth of 50 μm at the outermost surface when the hardness is measured inward from the outermost surface to the Vickers hardness, The coating layer consists of at least one compound selected from titanium carbide, titanium nitride, titanium carbide nitride, titanium carbonate-nitride compounds, (Ti, Al) N, and aluminum oxide, and also has a thickness of 0.5-20 μm. In the titanium-based cermet cutting edge, The solid phase of the dual structure is partially or wholly substituted with a discontinuous dual solid phase consisting of a core and a shell portion, The shell portion surrounds the core portion discontinuously such that the core portion is exposed on the metal bond, The discontinuous dual-structure hard phase occupies 30% or more of the total cermet surface area when observed with an electron microscope. The cermet cutting edge according to claim 1, wherein the average particle size of the hard phase of the cermet is 0.1 to 1.5 mu m, respectively. 3. The cermet cutting edge according to claim 2, wherein the average particle size of the hard phase of the cermet is 0.1 to 1.5 mu m, respectively. The cermet cutting edge according to claim 1, wherein the average particle size of the hard phase of the cermet is 0.1 to 1.5 mu m, respectively. The cermet cutting edge according to claim 4, wherein the average particle size of the hard phase of the cermet is 0.1 to 1.5 mu m, respectively. The cermet cutting edge according to claim 5, wherein the average particle size of the hard phase of the cermet is 0.5 to 1.2 mu m, respectively. The cermet cutting edge according to claim 6, wherein the average particle size of the hard phase of the cermet is 0.5 to 1.2 mu m, respectively. 8. The coated cermet cutting edge according to claim 7, wherein the average particle size of the hard phase of the cermet is 0.5 to 1.2 mu m, respectively. The cermet cutting edge according to claim 8, wherein the average particle size of the hard phase of the cermet is 0.5 to 1.2 mu m, respectively. The cermet cutting edge of claim 3, wherein the coating layer comprises a coating layer of (Ti, Al) N having a thickness of 0.5 to 5 μm. The cermet cutting edge of claim 4, wherein the coating layer comprises a coating layer of (Ti, Al) N having a thickness of 0.5 to 5 μm. The cermet cutting edge of claim 3, wherein the coating layer comprises a TiCN coating layer having a thickness of 0.5 to 5 μm including a longitudinal growth crystal structure in which crystal grains grow in a direction perpendicular to the surface of the cermet. The cermet cutting edge of claim 4, wherein the coating layer comprises a TiCN coating layer having a thickness of 0.5 to 5 μm including a longitudinal growth crystal structure in which crystal grains grow in a direction perpendicular to the surface of the cermet.