KR102450430B1 - Cemented carbide for cutting tools - Google Patents

Abstract

The present invention is a hard phase containing WC, a bonding phase containing one or more materials selected from Co, Ni and Fe, and a solid solution metal in a powder state (M ₁ M ₂ ... M _n ) In an alloy formed by bonding , The solid solution metal relates to a cemented carbide for a cutting tool, characterized in that the C, N is a metal element containing 1% by weight or less.

Description

Cemented carbide for cutting tools

The present invention relates to a cemented carbide for a cutting tool, and preferably to a cemented carbide for a cutting tool in which the high-temperature bending strength is enhanced by controlling the fractions of the HCP main phase and the FCC auxiliary phase.

Metal tools used for cutting are mainly made of cemented carbide, cermet, or other special steel, or tools made of ceramics. Among them, cemented carbide is an alloy material manufactured by mixing hard tungsten carbide (WC) particles with a bonding phase provided such as Co, Ni and Fe. is being used as

As a metal material for cutting tools, it is generally preferred to select a material with excellent hardness and wear resistance. Therefore, research to secure physical and chemical stability in a high-temperature environment is being actively conducted.

As an example, Korean Patent Application Laid-Open No. 10-2012-0086457 proposes a solid solution powder for manufacturing carbide containing solid solution metals such as Ti, V, Cr, Zr, Nb, Mo, Hf and Ta, and Japanese Patent Publication No. 05482602 discloses an alloy A cutting tool manufacturing method with enhanced thermal crack resistance by changing the crystal structure of the surface was proposed. The present applicant also proposed a method of forming a hard film using α-Al ₂ O ₃ as a base material on a cemented carbide base material through Korean Patent Registration No. 10-1737709. However, there is a demand for a cemented carbide manufacturing method that can be mass-produced commercially and has an excellent reinforcing effect compared to the production cost.

Republic of Korea Patent Publication No. 10-2012-0086457 (2012.08.03.) Japanese Patent Publication No. 05482602 (2014.02.28.) Republic of Korea Patent Publication No. 10-1737709 (2017.05.18.)

In order to solve the above problems, an object of the present invention is to provide an alloy for a cutting tool in which a metal element containing 1 wt% or less of C and N is dissolved in a bonding phase.

In addition, an object of the present invention is to provide an alloy for cutting tools in which the combined phase has both HCP and FCC structures, and the fraction thereof is 70 to 95.

One aspect of the present invention for achieving the above object is a solid-solution metal (M ₁ M ₂ ...M in a bonding phase and a powder state comprising at least one material selected from a hard phase including WC, Co, Ni and Fe. _n ) in the alloy formed by bonding, the solid solution metal relates to an alloy for a cutting tool, characterized in that the metal element containing C, N 1% by weight or less.

In the above aspect, based on a cross section of 15 μm to 100 μm depth from the surface of the cemented carbide for the cutting tool, the bonding phase may have a main phase of a dense hexagonal lattice (HCP) and an auxiliary phase of a face-centered cubic lattice (FCC). .

In the one aspect, the fraction of the main phase and the fraction of the accessory phase may satisfy the following relational expression (1).

[Relational Expression 1]

70 ≤ HC/(HC+FC) < 95

(In Equation 1, HC means the volume % of the main phase in the binding phase, and FC means the volume % of the accessory phase in the binding phase)

In the above aspect, when the bending force at 600 to 800 ° C is defined as _CH and the bending force at 20 to 30 °C is defined as C _L , C _H /C _L may be 60 to 80.

In one aspect, the main phase may have a volume % more than twice that of the accessory phase.

In one aspect, the solid solution metal may be one or more metal elements selected from the group consisting of Cr, Zr, Nb, Mo, Ti, Hf, Ta and V.

In the one aspect, the solid solution metal may be made of Cr, Ta and Ti.

In the one aspect, the cemented carbide for the cutting tool may satisfy the following relational expression (2).

[Relational Expression 2]

1.0 ≤ W _Cr + W _Ti ≤ 10.0

(In the above relation 2, W _C is Cr or Cr-containing alloy in weight%, and W _T is Ti or Ti-containing alloy in weight%)

In the one aspect, the cemented carbide for the cutting tool is based on 80 to 90% by weight of WC, 5 to 15% by weight of Co, 0.1 to 3% by weight of Cr or Cr-containing alloy, Ta or Ta-containing alloy 0.9 to 9.9% by weight, 1 to 10% by weight of Ti or an alloy containing Ti, and the remaining unavoidable impurities, wherein the Cr or alloy containing Cr and the alloy containing Ta or Ta may not both be 0% by weight.

According to the present invention, the solid solution metal strengthens the high-temperature bending strength by providing the metal element containing 1% or less of C and N in a powder state.

Through this, it is possible to prevent deformation of the cutting edge, which directly contributes to cutting, to maintain strength, and to contribute to the improvement of the lifespan of the cutting tool.

1 is a graph comparing the bending strength at room temperature and the bending strength at high temperature of a cemented carbide according to an embodiment of the present invention.
2 is a photograph taken after turning and cutting the S45C with Example 1 and CNMG120408.
3 is a photograph taken after turning and cutting SUS316 in Example 1 and SNMG120408.
4 is a photograph taken after turning and cutting Ti-6Al-4V with Example 1 and SNMG120408.

Hereinafter, a cemented carbide for a cutting tool according to the present invention will be described in detail. The drawings introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the drawings presented below and may be embodied in other forms, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. At this time, if there is no other definition in the technical terms and scientific terms used, it has the meaning commonly understood by those of ordinary skill in the art to which this invention belongs, and in the following description and accompanying drawings, the subject matter of the present invention Descriptions of known functions and configurations that may unnecessarily obscure will be omitted.

According to one aspect of the present invention, the present invention relates to a cemented carbide for a cutting tool to which one or more solid solution metals (M ₁ M ₂ ...M _n ) are added. Specifically, the cemented carbide for a cutting tool may be prepared by adding a hard phase containing WC, one or more bonding phases selected from Co, Ni and Fe, and a predetermined solid solution metal (M ₁ M ₂ ... M _n ). have. Hereinafter, Co as an element constituting the bonding phase will be described as an example, but the present invention is not limited thereto.

The solid solution metal (M ₁ M ₂ ...M _n ) may be one or more metals selected from the group consisting of Cr, Zr, Nb, Mo, Ti, Hf, Ta and V, preferably Cr, Ta and It may be any one or more metals selected from the group consisting of Ti.

According to an embodiment, the solid solution metal (M ₁ M ₂ ...M _n ) may be added in a powder state to the cemented carbide for the cutting tool, or an alloy containing 1 wt% or less of C and N in the solid solution metal. It can be added in the form of powder.

In the conventional WC-Co alloy, when a predetermined metal (M ₁ M ₂ ...M _n ) is added, carbide (M ₁ M ₂ ...C), nitride (WM ₁ M ₂ ...)N or Carbonitride (WM ₁ M ₂ ...) CN was added. In this case, the solubility of a predetermined metal (M ₁ M ₂ ...M _n ) to be added due to the C and N is relatively decreased.

However, in the present invention, the predetermined metal may be added as a metal powder other than carbide, nitride, or carbonitride, more preferably in the form of an alloy in which C and N are combined in an amount of 1 wt% or less. When a powder in which the predetermined metal is combined with C and N and C and N in an amount of 1% by weight or less is added, a large amount can be dissolved under the same conditions because the rate of dissolution in the Co bond phase is faster. For this reason, it is possible to increase the solubility of the metal in the Co bonding phase. Through this, it is possible to improve the tensile strength of the cemented carbide for cutting tools at room temperature and high temperature.

According to another aspect of the present invention, the Co bonding phase may be divided into two or more lattice phases by mixing and carbonizing or carbonitriding the solid solution metal (M ₁ M ₂ ...M _n ). In this case, one lattice phase may have a volume % that is twice or more higher than that of the other lattice phase existing in the Co bonding phase. Hereinafter, a lattice phase having a volume % greater than or equal to twice the volume may be defined as a main phase, and a lattice phase having a relatively low volume % may be defined as an accessory phase.

According to an embodiment, the main phase in the Co bonding phase may be Co (hereinafter α-Co) having a dense hexagonal lattice (HCP) structure, and the auxiliary phase is Co (hereinafter β-Co) having a face-centered cubic lattice (FCC) structure. can be

In general, when a metal element is dissolved in the Co bond phase, α-Co, which is stable at room temperature among the α-Co and the β-Co, increases. That is, an increase in the fraction of α-Co in the Co bonding phase means that more metal elements are dissolved in the Co bonding phase under the same firing conditions.

In addition, the metal element may be dissolved between the lattices of the Co bonding phase to form an interstitial solid solution. As a result, the lattice constant of Co can be increased to 3.6 Å or more, and at the same time, solid solution strengthening in the cemented carbide for cutting tools is increased due to the interstitial solid solution, so that the mechanical properties of the cemented carbide for cutting tools can be improved. In other words, the mechanical properties of the cemented carbide for the cutting tool can be strengthened by adjusting the volume% of α-Co and the volume% of β-Co in the Co bonding phase.

In general, in cemented carbide for cutting tools, a toughness reinforcing layer composed of WC-Co is formed at a depth of 5 to 10 μm from the surface, and a Co bonding phase may be formed at a depth of 10 μm or more. For this reason, based on a cross-section having a depth of 10 μm or more from the surface, more preferably 15 to 100 μm from the surface, the volume % of α-Co and the volume % of the β-Co are within the range satisfying the following relation 1 can be selected from

[Relational Expression 1]

70 ≤ HC/(HC+FC) < 95

(In Relation 1, HC means volume % of α-Co in Co, and FC means volume % of β-Co in Co)

If the HC/(HC+FC) is less than 70, it means that the amount of metal element dissolved in the Co bonding phase is insufficient, which is due to the lack of an interstitial solid solution formed in the Co bonding phase. This means that the strength can be reduced. In fact, if the HC/(HC+FC) is less than 70, the wear of the tool is fast in high-speed cutting and thermal deformation may occur. This results in a shortened tool life. On the other hand, when the HC/(HC+FC) exceeds 95, the interstitial solid solution formed in the Co bonding phase is excessive, so that toughness decreases and brittleness increases, so that it can be easily broken. For this reason, the HC/(HC+FC) is preferably 70 to 95, more preferably 75 to 90.

The cemented carbide for a cutting tool according to the first aspect of the present invention is based on 80 to 90% by weight of WC and 5 to 15% by weight of Co, and 0.1 to 3% by weight of Cr or Cr-containing alloy, Ta or Ta-containing alloy 0.9 to 9.9% by weight, Ti or an alloy containing Ti, 1 to 10% by weight, and the remaining unavoidable impurities.

As described above, the cemented carbide for the cutting tool may contain at least 0.1% by weight of Co, preferably 0.1 to 15% by weight. More preferably, it may contain 5 to 10% by weight.

Specifically, when the Co is out of the above range, for example, if the weight % of the Co is less than 0.1, the toughness of the cemented carbide for the cutting tool is lowered, and the hardness is reduced and abrasion is easy. Conversely, when the Co content is 15% by weight or more, the bonding between the WC hard phase and the Co bonding phase is weakened, and bending strength (anti-folding force) and breakage resistance may be reduced. For this reason, the Co content is preferably 0.1 wt% or more and less than 15 wt%.

According to an embodiment, the Co may be included as a single or mixed powder in which other metal components such as Ni are partially substituted, and the Co powder may have an average particle size of 1.0 to 1.8 μm. In general, the smaller the particle size of Co and the more uniformly dispersed, the better the mechanical properties. However, if the average particle size of Co powder is less than 1.0 μm, the bonding phase containing Co is easily combined with the WC hard phase and other metal additives, resulting in fatigue of cemented carbide products. The resistance to impact is reduced, and at the same time, the time required to refine the powder increases, which may reduce productivity.

On the other hand, if the average particle size of the Co powder exceeds 1.8㎛, the Co powder is not uniformly distributed, and the fine particle area and the coarse particle area are unevenly distributed. .

In addition, the solid solution metal (M ₁ M ₂ ...M _n ) included in the cutting tool may be provided as an alloy including at least one of Cr, Ta and Ti or Cr, Ta and Ti, and the solid solution metal is It may be added in powder form.

At this time, the average particle size of the solid solution metal (M ₁ M ₂ ...M _n ) may be 0.3 to 2.0㎛. If the average particle size of the powder is less than 0.3㎛, excessive cost and time are consumed to atomize the powder, and thus productivity may decrease. and the life of the tool may be reduced. In addition, if additional coating is performed on the surface of the cutting tool, it may cause the coating to peel off.

According to an embodiment, the weight % of Cr and Ti may be selected within a range satisfying Equation 2 below.

[Relational Expression 2]

1.0 ≤ W _Cr + W _Ti ≤ 10.0

(In the above relation 2, W _C is Cr or Cr-containing alloy in weight%, and W _T is Ti or Ti-containing alloy in weight%)

If the sum of W _Cr and W _Ti is less than 1.0% by weight, the content of Cr and Ti is too small to expect a solid solution strengthening effect, and grain growth may occur in the WC to reduce cutting performance. On the other hand, if the sum of W _Cr and W _Ti is 10.0 or more, the thermal diffusivity of the cemented carbide for the cutting tool is lowered, so that the thermal cracking resistance may be reduced. This can increase the probability of cracks and fractures occurring during the cutting process, and cause surface peeling.

According to an embodiment, the cemented carbide for the cutting tool is based on 80 to 90% by weight of WC, 5 to 15% by weight of Co, 0.1 to 3% by weight of Cr or Cr-containing alloy, and 0.9 to 0.9% of Ta or Ta-containing alloy to 9.9% by weight of Ti or an alloy containing Ti, from 1% to 10% by weight of the remaining unavoidable impurities, wherein the Cr or alloy containing Cr and the alloy containing Ta or Ta may not both be 0% by weight.

In addition, the present invention can form one or more wear-resistant layers on the surface of the base material by using the above-described cemented carbide for cutting tools as a base material. As a method of forming the wear-resistant layer, it may be formed using any one or more methods selected from known physical vapor deposition (PVD) or chemical vapor deposition (CVD). At this time, the surface roughness (Ra) of the wear-resistant layer formed on the edge portion of the cutting tool may be formed to a predetermined standard, for example, 5.0 μm or less, but is not limited thereto.

Hereinafter, the cemented carbide for a cutting tool according to the present invention will be described in more detail through examples. However, the following examples are only a reference for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

Also, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of effectively describing particular embodiments only and is not intended to limit the invention. In addition, the unit of additives not specifically described in the specification may be weight %.

[Example 1]

WC, Co and Cr, Ta and WTiCN metal powders to be added to the Co were prepared. Then, WC 82.5% by weight Co 7.5% by weight, Cr 1% by weight, Ta 5% by weight and WTiCN 4% by weight were mixed to prepare a raw material powder.

The raw material powder was weighed to have a total weight of 1,500 g, 20 to 30 kg of hardened carbide balls were filled in the weighed raw material powder, added to 1 L of an alcohol solvent, and milled for 15 hours. It was dried for 1 hour to prepare a mixed powder. The mixed powder was pressed at a pressure of 2 ton/cm 2 through a mold for a shape of CNMG120408 and SNMG120408 and a 24 mm x 8 mm x 4 mm block type to prepare a molded article.

Next, a dewaxing process was performed at 600° C., and the organic binder component added to the molded article manufacturing process was removed. After that, sintering was carried out at 1,400° C., within 2 hours at 100 bar of Ar. The sintered metal was cooled to 1,000° C. over 60 minutes in an inert gas atmosphere. Finally, the sintered metal cooled to 1,000 °C was naturally cooled.

[Example 2]

All processes were performed in the same manner as in Example 1 except that the metal sintered at 1,400° C. was cooled to 1,000° C. over 30 minutes.

[Example 3]

All processes were performed in the same manner as in Example 1 except that Cr and Ta metal powder were replaced with Cr.

[Example 4]

All processes were performed in the same manner as in Example 3 except that the metal sintered at 1,400° C. was cooled to 1,000° C. over 30 minutes.

[Example 5]

All processes were performed in the same manner as in Example 1 except that the Cr and Ta metal powders were replaced with Ta.

[Example 6]

All processes were performed in the same manner as in Example 5 except that the metal sintered at 1,400° C. was cooled to 1,000° C. over 30 minutes.

[Comparative Example 1]

All processes were performed in the same manner as in Example 1 except that Cr and Ta metal powder were replaced with Cr ₃ C ₂ and TaC.

[Comparative Example 2]

All processes were performed in the same manner as in Example 1 except that Cr and Ta metal powder were replaced with Cr ₃ C ₂ .

[Comparative Example 3]

All processes were performed in the same manner as in Example 1 except that the Cr and Ta metal powders were replaced with TaC.

[Analysis and Performance Evaluation]

1) EBSD analysis:

In order to analyze the microstructure of the cemented carbide for cutting tools prepared in Examples 1 to 6 and Comparative Examples 1 to 3, EBSD (Electron Backscatter Diffraction) analysis was performed. In Table 1 below, α-Co denotes the volume% of the dense hexagonal lattice (HCP) structure in the Co-bonded phase, and β-Co denotes the volume% of the face-centered cubic (FCC) structure in the Co-bonded phase, α/(α+) β) means HC/(HC+FC) in Relation 1 below.

[Relational Expression 1]

70 ≤ HC/(HC+FC) < 95

(In Relation 1, HC means volume % of α-Co in Co, and FC means volume % of β-Co in Co)

2) High temperature/room temperature resistance measurement:

High temperature and room temperature tensile strength was measured based on JIS B-4104 test method. Specifically, a test piece having a length of 24.0 mm, a width of 8.0 mm, and a thickness of 4.0 mm was prepared, and the tensile strength was measured at a room temperature of 25°C and a high temperature of 700°C. The high-temperature tensile strength was measured after maintaining the test piece at 700° C. for 2 hours.

The above-described analysis results are summarized in Table 1 below.

α-Co
(%) β-Co
(%) α/(α+β)
(%) Drag force (kgf/㎟) 700℃ 25℃ C _H /C _L Example 1 0.019 0.005 79 200 265 75 Example 2 0.02 0.0045 82 221 280 73 Example 3 0.03 0.0078 80 240 330 73 Example 4 0.04 0.0073 85 260 350 74 Example 5 0.022 0.008 75 245 310 70 Example 6 0.022 0.007 76 260 321 73 Comparative Example 1 0.02 0.009 69 135 230 59 Comparative Example 2 0.017 0.0078 68 165 300 55 Comparative Example 3 0.018 0.0079 69 145 285 51

In Table 1, _CH means the bending force at 700°C, that is, the high-temperature bending strength, and C _L is the bending strength at 25°C, that is, the room-temperature bending strength. In addition, C _H / C _L means the high temperature bending strength compared to the room temperature bending strength, and it was calculated by multiplying the value obtained by dividing the _CH by the _CL by 100.

According to Table 1, the cemented carbide prepared in Examples 1 to 6 of the present invention has a high-temperature _tensile strength ( _CH ) at 700 ° C. that can be checked

Conversely, in the case of Comparative Examples 1 to 3 prepared by the conventional method, the room temperature tensile strength ( _CL ) at 25 ° C. was 200 to 300, which did not show a significant difference compared to Examples 1 to 6, but at 700 ° C. ( _CH ) is 100 to 200, it can be seen that the high-temperature tensile strength ( _CH ) is improved by about 1.4 times or more when compared on average. As described above, in the case of Examples 1 to 6 in which Cr Ti was added as a powder, more Cr and Ta were dissolved in the Co bonding phase under the same conditions to form an interstitial solid solution, which resulted in solid solution strengthening. It can be seen that the employment yield strength ( _CH ) is improved by increasing .

On the other hand, it can be seen that Comparative Examples 1 to 3 added as carbides or nitrides containing a predetermined amount of carbon (C) have relatively small amounts of Cr and Ta dissolved therein, so that the high-temperature tensile strength ( _CH ) is relatively reduced. have.

In addition, it can be seen that the tensile strength at room temperature is also improved to 250 to 350 in Examples 1 to 6, compared to 230 to 300 in Comparative Examples 1 to 3.

Finally, it can be seen that the high temperature resistance to bending strength (C _H / C _L ) of Examples 1 to 6 is 70 to 75, which is about 1.3 times higher than that of 51 to 59 of Comparative Examples 1 to 3 . Through this, it can be seen that the interstitial solid solution contributes to the improvement of strength even at high temperature and room temperature.

1 is a graph comparing the bending strength at room temperature and the bending strength at high temperature of a cemented carbide according to an embodiment of the present invention.

Referring to FIG. 1 , as described above, the room temperature coercive force ( _CL ) and the high temperature coercive force (CH ) of Examples 1 to 6 were both the room temperature coercive force ( _CL ) and the high temperature tensile force (C _H ) of Comparative Examples 1 to 3 ( It can be seen that the improvement compared to C _H ) was confirmed. In addition, it can be seen that the reduction rate (%) of the tensile force decreased when the temperature was increased from room temperature to high temperature, and Examples 1 to 6 were further reduced than Comparative Examples 1 to 3. Through this, it can be confirmed that the cemented carbide for a cutting tool manufactured according to an embodiment of the present invention has high tensile strength at both room temperature and high temperature, and the decrease in physical properties as the temperature increases can also be minimized.

3) Cutting evaluation comparison experiment

Cutting life was compared with the cemented carbide for a cutting tool manufactured according to Example 1 and CNMG120408, a cutting tool steel commonly used. Specifically, the cemented carbide for a cutting tool prepared according to Example 1 was manufactured with a cutting insert having the same size as CNMG120408 (according to ISO-13399 regulations), and turned by turning under the conditions shown in Table 2 below. The cutting edge after cutting is disclosed in FIGS. 2 to 4 .

work material Vc(m/min) fn(mm/min) AP(mm) coolant Figure 1 S45C 250 0.5 2.0 wet Figure 2 SUS316 150 0.1 1.0 wet Fig. 3 Ti-6Al-4V 50 0.2 1.0 wet

In Table 2, Vc is the cutting speed, F is the feed rate, and AP is the depth of cut.

Referring to FIG. 2 , as a result of performing a cutting experiment on a workpiece made of S45C material, no cracks or wear was found in Example 1 (FIG. 2 (a)). However, irregular cracks were found in the CNMG120408 (FIG. 2(b)). This shows that Example 1 is superior in chipping resistance and abrasion resistance compared to conventional products.

Referring to FIG. 3 , as a result of performing a cutting experiment on a SUS316 workpiece, it was confirmed that wear occurred in both Example 1 and SNMG120408, but the SNMG120408 ((b) of FIG. 3) had an irregular wear surface. formation can be observed. This shows that Example 1 is excellent in plastic deformation resistance compared to conventional products.

Finally, referring to FIG. 4 , as a result of performing a cutting experiment on a Ti-6Al-4V workpiece, it was confirmed that wear occurred in both Example 1 and SNMG120408 similar to FIG. 3 . However, in the SNMG120408 (FIG. 4(b)), it can be seen that the wear surface is irregularly formed. This shows that Example 1 is excellent in plastic deformation resistance compared to conventional products.

Although the present invention has been described through specific matters and limited examples as described above, these are only provided to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and the present invention pertains to Various modifications and variations are possible from these descriptions by those of ordinary skill in the art.

Accordingly, the spirit of the present invention should not be limited to the described embodiments, and not only the claims to be described below, but also all of the claims and equivalents or equivalent modifications will fall within the scope of the spirit of the present invention.

Claims (11)

In the alloy comprising a hard phase containing WC, a bonding phase containing at least one material selected from Co, Ni and Fe, and a solid solution metal in a powder state (M ₁ M ₂ ... M _n ) are combined,
The solid solution metal is a metal element containing 1 wt% or less of C and N,
Based on the cross section of 15 to 100㎛ depth from the surface of the cemented carbide for the cutting tool,
The bonding phase has a main phase of a dense hexagonal lattice (HCP) and a subphase of a face-centered cubic lattice (FCC),
Cemented carbide for cutting tools, characterized in that the fraction of the main phase and the fraction of the accessory phase satisfy the following relational expression 1.
[Relational Expression 1]
70 ≤ HC/(HC+FC) < 95
(In Equation 1, HC means the volume % of the main phase in the binding phase, and FC means the volume % of the accessory phase in the binding phase) delete delete The method of claim 1,
When the bending force at 600 to 800° C. is defined as _CH and the bending force at 20 to 30° C. is defined as C _L , C _H /C _L may be from 60 to 80. The method of claim 1,
The main phase is a cemented carbide for cutting tools, characterized in that it has a volume % more than twice that of the auxiliary phase. The method of claim 1,
The solid solution metal is one or more metal elements selected from the group consisting of Cr, Zr, Nb, Mo, Ti, Hf, Ta and V, cemented carbide for a cutting tool. 7. The method of claim 6,
The solid solution metal is a cemented carbide for a cutting tool, characterized in that made of Cr, Ta and Ti. The method of claim 1,
The cemented carbide for a cutting tool is a cemented carbide for a cutting tool that satisfies the following relation (2).
[Relational Expression 2]
1.0 ≤ W _Cr + W _Ti ≤ 10.0
(In the above relation 2, W _C is Cr or Cr-containing alloy in weight%, and W _T is Ti or Ti-containing alloy in weight%) 9. The method of claim 8,
The cemented carbide for the cutting tool,
Based on 80 to 90% by weight of WC, 5 to 15% by weight of Co,
0.1 to 3% by weight of Cr or an alloy containing Cr,
0.9 to 9.9% by weight of Ta or an alloy containing Ta;
A cemented carbide for a cutting tool, comprising 1 to 10% by weight of Ti or a Ti-containing alloy and the remaining unavoidable impurities, characterized in that neither the Cr or Cr-containing alloy and the Ta or Ta-containing alloy are 0% by weight. 10. The method of claim 9,
The Ti-containing alloy is a cemented carbide for a cutting tool provided at least one selected from the group consisting of WTi, WTiC, TiC, TiN, TiAl, TiCN, AlTiSi and WTiCN. 11. The method of claim 10,
The Ti-containing alloy is a cemented carbide for a cutting tool, characterized in that WTiCN.

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