WO2024014412A1

WO2024014412A1 - Cermet sintered body, cermet tool and cutting tool

Info

Publication number: WO2024014412A1
Application number: PCT/JP2023/025287
Authority: WO
Inventors: 涼馬野見山; 綾乃根岸; 勇一郎熊
Original assignee: 京セラ株式会社
Priority date: 2022-07-11
Filing date: 2023-07-07
Publication date: 2024-01-18

Abstract

A cermet sintered body according to the present disclosure comprises: a first hard phase mainly composed of TiCN; a second hard phase that is a composite carbonitride solid solution of Ti and at least one of the metals of Groups 4, 5, and 6 of the periodic table; and a binder phase containing W and at least one of Co and Ni. The average particle size of the second hard phase in an internal region and the average particle size of the second hard phase in a surface region are each 0.35-0.6 μm. The strength σ1 in the surface region and the strength σ2 in the internal region are each 2300 MPa or more, and the strength ratio of σ1 to σ2 is 0.8 or more.

Description

Cermet sintered bodies, cermet tools and cutting tools

The present disclosure relates to a cermet sintered body, a cermet tool, and a cutting tool.

Cermet sintered bodies containing titanium (Ti) as the main component are widely used as substrates for parts that require wear resistance, sliding properties, and chipping resistance, such as cutting tools, wear-resistant parts, and sliding parts. ing.

Patent No. 3099834

A cermet sintered body according to one aspect of the present disclosure includes a first hard phase mainly composed of TiCN and a composite carbonitride solid solution of Ti and at least one metal of

Groups

4, 5, and 6 of the periodic table. 2 hard phases, and a binder phase containing at least one of Co and Ni and W. The average particle diameter d _2in of the second hard phase in the internal region and the average particle diameter d _2sf of the second hard phase in the surface region are both 0.35 μm or more and 0.6 μm or less. The intensity σ1 in the surface region and the intensity σ2 in the internal region are both 2300 MPa or more, and the intensity ratio of σ1 to σ2 (σ1/σ2) is 0.8 or more.

FIG. 1 is a perspective view showing an example of a cermet tool according to an embodiment. FIG. 2 is a side sectional view showing an example of the cermet tool according to the embodiment. FIG. 3 is a copy of a scanning electron micrograph of a cross section of a cermet sintered body. FIG. 4 is a front view showing an example of the cutting tool according to the embodiment. FIG. 5 shows sample No. 1, which is a comparative example. 1 and sample No. 1 which is an example. 3 is a graph showing the anti-resistance strength in the surface area and the internal area for No. 3. FIG. 6 shows sample No. 1, which is a comparative example. 1 and sample No. 1 which is an example. 3 is a graph showing the thermal shock strength of No. 3.

Hereinafter, embodiments (hereinafter referred to as "embodiments") for implementing a cermet sintered body, a cermet tool, and a cutting tool according to the present disclosure will be described in detail with reference to the drawings. Note that this embodiment does not limit the cermet sintered body, cermet tool, and cutting tool according to the present disclosure. Moreover, each embodiment can be combined as appropriate within the range that does not conflict with the processing contents. Further, in each of the embodiments below, the same parts are given the same reference numerals, and redundant explanations will be omitted.

In addition, in the embodiments described below, expressions such as "constant", "orthogonal", "perpendicular", or "parallel" may be used, but these expressions strictly do not mean "constant", "orthogonal", "parallel", etc. They do not need to be "perpendicular" or "parallel". That is, each of the above expressions allows for deviations in manufacturing accuracy, installation accuracy, etc., for example.

There is room for further improvement in conventional cermet sintered bodies in terms of improving the thermal shock resistance on the surface. Therefore, it is expected to provide a cermet sintered body, a cermet tool, and a cutting tool that have high thermal shock resistance on the surface.

<Cermet tools>
FIG. 1 is a perspective view showing an example of a cermet tool according to an embodiment. Moreover, FIG. 2 is a side sectional view showing an example of the cermet tool according to the embodiment. FIG. 3 is a copy of a scanning electron micrograph of a cross section of a cermet sintered body.

As shown in FIGS. 1 and 2, the cermet tool 1 according to the embodiment includes a base body 2 and a coating layer 3.

The base 2 has, for example, a hexahedral shape in which the top and bottom surfaces (the surfaces intersecting the Z-axis shown in FIG. 1) are parallelograms.

One corner of the base 2 functions as a cutting edge. The cutting edge has a first surface and a second surface connected to the first surface. The first surface is, for example, the upper surface of the base 2. The second surface is, for example, a side surface of the base body 2. In the embodiment, the first surface functions as a "rake surface" that scoops up chips generated by cutting, and the second surface functions as a "relief surface." A cutting blade is located on at least a portion of the ridgeline where the first surface and the second surface intersect, and the cermet tool 1 cuts the workpiece by applying the cutting blade to the workpiece.

A through hole 21 that vertically penetrates the base 2 may be located in the center of the base 2. In this case, a screw 75 for attaching the cermet tool 1 to a holder 70, which will be described later, is inserted into the through hole 21 (see FIG. 4).

The base body 2 is made of a cermet sintered body. The cermet sintered body contains Ti (titanium) and W (tungsten), and also contains at least one of Co (cobalt) and Ni (nickel).

As shown in FIG. 3, the base body 2, which is a cermet sintered body, contains a hard phase 5 and a bonding phase 6. Specifically, the substrate 2 is formed by solid solution of TiCN and at least a portion of carbides, nitrides, and carbonitrides of at least one metal of

Groups

4, 5, and 6 of the periodic table other than Ti. A hard phase 5 is bonded with a bonding phase 6. The bonded phase 6 contains W and at least one of Co and Ni.

The first hard phase is a hard phase containing TiCN as a main component. In the present disclosure, the term "main component" refers to, for example, 55% by mass or more when the entire hard phase of the constituent components is 100% by mass.

Specifically, the first hard phase contains 80% by weight or more of Ti as metal components, and 1% or more by weight of W and one or more metals from

Groups

4, 5, and 6 of the periodic table. Contains less than %. Moreover, the first hard phase contains Co and/or Ni as the remainder.

The second hard phase is a hard phase made of a composite carbonitride solid solution of Ti and at least one metal of

Groups

4, 5, and 6 of the periodic table. Specifically, the second hard phase contains Ti in a total amount of 30% or more and 70% by weight, W and one or more metals from

Groups

4, 5, and 6 of the periodic table in a total amount of 70% or more and 30% by weight. % or less, and the total amount of binder phase metals such as Co and/or Ni is 0% or more and 3% or less by weight.

As shown in FIG. 3, in an image of an arbitrary cross section of a cermet obtained by a scanning electron microscope (SEM), specifically, in a backscattered electron image, the first hard phase 5a is relatively smaller than the second hard phase 5b. The second hard phase 5b is observed to be black, and the second hard phase 5b is relatively grayer than the first hard phase 5a. The second hard phase 5b also includes a double cored structure in which the first hard phase 5a is the core and the second hard phase 5b is the peripheral part. Note that it is not necessary that all the second hard phases 5b have a cored structure.

Here, a region centered at a depth of 10 μm from the surface of the base 2 is defined as the base 2, in other words, the surface region of the cermet sintered body. The width of the surface region in the depth direction of the base body 2 may be, for example, 20 μm. Further, a region centered at an arbitrary position 0.4 mm or more deep from the surface of the base 2 is defined as an internal region of the base 2. The width of the internal region in the depth direction of the base body 2 may be, for example, 20 μm.

In the base body 2 according to the embodiment, the average particle diameter d _2in of the second hard phase 5b in the internal region and the average particle diameter d _2sf of the second hard phase 5b in the surface region are both 0.35 μm or more and 0.6 μm. It is as follows. Further, the area ratio S _2in of the second hard phase 5b to the entire hard phase in the internal region and the area ratio S _2sf of the second hard phase 5b to the entire hard phase in the surface area are both 50 area % or more and 80 area %. It is as follows. In addition, the intensity σ1 in the surface region and the intensity σ2 in the inner region are both 2300 MPa or more, and the intensity ratio (σ1/σ2) of the intensity σ1 in the surface region to the intensity σ2 in the inner region is 0.8 That's all.

According to this configuration, it is possible to increase the strength on the surface of the cermet sintered body, reduce the increase in Young's modulus on the cermet surface, and improve the thermal shock resistance on the cermet surface. In particular, it is possible to improve the wear resistance and chipping resistance of the cermet even under conditions where severe thermal shock occurs, such as during wet interrupted cutting.

In the base body 2 according to the embodiment, the average particle diameter d _1in of the first hard phase 5a in the internal region and the average particle diameter d _1sf of the first hard phase 5a in the surface region are both 0.25 μm or more and 0.35 μm. It may be the following. Further, the average particle diameter d _1in of the first hard phase 5a in the internal region and the average particle diameter d _1sf of the first hard phase 5a in the surface region may both be 0.25 μm or more and 0.3 μm or less. . Further, the area ratio S _1in of the first hard phase 5a to the entire hard phase in the internal region and the area ratio S _1sf of the first hard phase 5a to the entire hard phase in the surface area are both 20 area % or more and 35 area %. It may be the following. In the base body 2 having such a configuration, the average grain size d _1sf and area ratio S _1sf of the first hard phase 5a in the surface region are the same as the average grain size d _1in and area ratio S _{1in of} the first hard phase 5a in the inner region. The thermal shock resistance on the surface can be improved to the same extent as the thermal shock resistance on the inside.

In the base body 2 according to the embodiment, the hardness H1 in the surface region and the hardness H2 in the internal region may both be 1450 HV or more. In this case, the absolute value |H1−H2| of the difference between the hardness H1 in the surface region and the hardness H2 in the internal region may be 50 or less. In the base body 2 having such a configuration, the hardness H1 in the surface region is approximately the same as the hardness H2 in the internal region, so that the thermal shock resistance at the surface can be increased to the same extent as the thermal shock resistance inside.

(Coating layer 3)
The coating layer 3 is coated on the base body 2 for the purpose of improving the wear resistance, heat resistance, etc. of the base body 2, for example. Although FIG. 2 shows an example in which the coating layer 3 covers the entire surface of the base 2, the coating layer 3 does not necessarily need to cover the entire surface of the base 2. The covering layer 3 only needs to be located on at least a portion of the surface of the base 2. When the coating layer 3 is located on the first surface, here the upper surface, of the base body 2, the first surface has high wear resistance and heat resistance. When the coating layer 3 is located on the second surface of the base body 2, in this case on the side surface, the second surface has high wear resistance and heat resistance.

The coating layer 3 is made of, for example, at least one metal element selected from

Group

4, 5, and 6 elements of the periodic table, Al (aluminum), and Si (silicon), and C (carbon), N (nitrogen), and O. (oxygen). With such a configuration, the oxidation resistance of the coating layer 3 is improved. This further improves the wear resistance of the coating layer 3. The covering layer 3 may be one layer. Moreover, the cermet tool 1 may have the coating layer 3 laminated in a layered manner, that is, two or more layers.

(analysis method)
The average particle size (d _1in , d _2in , d _1sf , d _2sf ) and the area ratio (S _1in , S _2in , S _1sf , S _2sf ) can be determined, for example, by the following procedure.

A cross section of the cermet sintered body is photographed with a scanning electron microscope (SEM) at a magnification of 10,000 times to obtain a backscattered electron image. A region including a position at a depth of 10 μm from the surface of the cermet sintered body is defined as a surface region, and a region including a position at a depth of 400 μm from the surface of the cermet sintered body is defined as an internal region. In each region, draw a straight line with a length of 10 μm in the direction parallel to the surface of the cermet sintered body, and calculate each phase from the length of the line segment that crosses the first hard phase and the length of the line segment that crosses the second hard phase. The diameter, specifically the particle diameter and abundance ratio, specifically the area ratio may be determined.

Specifically, the average particle diameter of the first hard phase may be calculated by dividing the total length of line segments that cross the first hard phase by the number of first hard phases that the line crosses. Similarly, the average particle diameter of the second hard phase may be calculated by dividing the total length of line segments that cross the second hard phase by the number of second hard phases that the line crosses.

Note that when calculating the average particle size of the first hard phase and the second hard phase, particles smaller than a specific value may be excluded from the target in order to avoid measurement variations. For example, if 0.1 μm is set as a specific value, and the first hard phase whose line segment is 0.1 μm or more is the first measurement target, the total length of the line segments in this first measurement target is the line The average particle size of the first hard phase may be calculated by dividing by the number of first measurement objects crossed by the first measurement target. Similarly, if the second hard phase whose line segment is 0.1 μm or more is the second measurement target, the total length of the line segments in this second measurement target is the number of second measurement targets crossed by the line. By dividing, the average particle size of the second hard phase may be calculated.

Further, the length of the line segment that crosses the first hard phase when the sum of the length of the line segment that crosses the first hard phase and the total length of the line segment that crosses the second hard phase is taken as 100%. The total ratio may be calculated as the area ratio of the first hard phase. Similarly, the length of the line segment that crosses the second hard phase when the sum of the lengths of the line segments that cross the first hard phase and the total length of the line segments that cross the second hard phase is taken as 100%. The total ratio of the hard phase may be calculated as the area ratio of the second hard phase. At this time, the bonded phase region is excluded. Further, the measurement may preferably be performed by measuring three visual fields and taking the average thereof. It can also be measured using a commercially available image analysis device.

(Production method)
Next, a method for manufacturing the base body 2, which is a cermet sintered body, will be explained.

In manufacturing the cermet sintered body of the present disclosure, TiCN powder is utilized. This TiCN raw material powder may be one that is generally used in the production of cermets. The TiCN raw material powder may have already undergone a pulverization process. Furthermore, if the TiCN raw material powder has not undergone a pulverization process, it may be pulverized using a rotary mill and media.

When the TiCN raw powder undergoes a pulverization process, dislocations occur inside the TiCN raw powder, and one or more of V, Nb, Ta, Cr, Mo, W, Co, and Ni are present at the positions where these dislocations exist. metal elements move.

It is preferable to use TiCN raw material powder having such dislocations, carbides of the metals mentioned above, and Co or Ni as the binder phase as raw materials.

A raw material powder of TiCN having dislocations may be used, and the binder phase components such as Co and Ni may be 14% by mass or more and 22% by mass or less. When the binder phase component is within the above range, the cermet that is the base has high toughness and high hardness.

Note that as the components containing V, Nb, Ta, Cr, Mo, and W, carbides of the respective metal elements may be used.

After mixing the raw materials having the above-mentioned composition, they are fired. The firing step may be, for example, the following steps.
(a) Step of raising the temperature from room temperature to 1100°C in vacuum (b) Holding the temperature at 1100°C in vacuum for 1 to 2.5 hours (c) Injecting N2 gas into the firing furnace at 1100°C and changing the pressure inside the firing furnace to pressure P1, which is 5 Pa, and then increasing the temperature from 1100°C to temperature T1 of 1150 to 1300°C at a heating rate r1 of 0.1 to 2°C/min (d ) Holding at temperature T1 for 0.5 to 2 hours (e) At temperature T1, change the pressure in the firing furnace to pressure P2, which is 300 to 2000 Pa higher than pressure P1, and then change from temperature T1 to 1300 to 2000 Pa. A step of raising the temperature at a heating rate r2 of 1 to 5° C./min to a temperature T2 of 1450° C. (f) A step of holding the temperature T2 for 0.25 to 1.5 hours (g) A step of reducing the pressure in the firing furnace. Step (h) of changing the pressure P3 to 30 to 1000 Pa, which is lower than the pressure P2, and then increasing the temperature from the temperature T2 to the temperature T3 of 1450 to 1600 °C at a temperature increase rate r3 of 2 to 10 °C/min (h) temperature T3 Specifically, after 0.25 hours have passed, the pressure in the firing furnace is gradually reduced from P3 to 5 Pa while applying the pressure in the firing furnace for 0.25 hours. Thereafter, the pressure is maintained at 5 Pa for 0.5 hours.
(i) Step of changing to an Ar gas atmosphere at a pressure P4 of 10,000 Pa to 80,000 Pa while lowering the temperature from temperature T3 to temperature T4 of 100°C or less at a cooling rate r4 of 10 to 50°C/min.

The cermet sintered body of the present disclosure can be produced by firing a molded body having the above-described composition in the above-described firing process.

Thereafter, a covering layer 3 may be provided as necessary. The coating layer 3 may be a so-called hard film, and may be formed by, for example, a PVD method or a CVD method. The coating film may be a single layer or a laminated film.

<Cutting tools>
Next, the configuration of a cutting tool including the cermet tool 1 described above will be described with reference to FIG. 4. FIG. 4 is a front view showing an example of the cutting tool according to the embodiment.

As shown in FIG. 4, the cutting tool 100 according to the embodiment includes a cermet tool 1 and a holder 70 for fixing the cermet tool 1.

The holder 70 is a rod-shaped member that extends from the first end toward the second end. As an example, the first end is the top end in FIG. 4, and the second end is the bottom end in FIG. The holder 70 is made of steel or cast iron, for example. In particular, it is preferable to use steel with high toughness among these members.

The holder 70 has a pocket 73 at the first end. The pocket 73 is a portion on which the cermet tool 1 is mounted, and has a seating surface that intersects with the rotational direction of the workpiece and a restraining side surface that is inclined with respect to the seating surface. The seating surface is provided with a screw hole into which a screw 75, which will be described later, is screwed.

The cermet tool 1 is located in the pocket 73 of the holder 70 and is attached to the holder 70 by a screw 75. That is, the screw 75 is inserted into the through hole 21 of the cermet tool 1, and the tip of the screw 75 is inserted into a screw hole formed in the seating surface of the pocket 73, so that the screw portions are screwed together. Thereby, the cermet tool 1 is attached to the holder 70 so that the cutting edge portion protrudes outward from the holder 70.

In the embodiment, a cutting tool used for so-called turning is exemplified. Examples of turning processing include inner diameter processing, outer diameter processing, and grooving. Note that the cutting tool is not limited to one used for turning. For example, the cermet tool 1 may be used as a cutting tool used for milling. Examples of cutting tools used in milling include milling cutters such as flat milling cutters, face milling cutters, side milling cutters, and groove milling cutters, and end mills such as single-flute end mills, multi-flute end mills, tapered blade end mills, and ball end mills. .

Examples of the present disclosure will be specifically described below. Note that the present disclosure is not limited to the examples shown below.

Sample No. which is a cermet sintered body. 3 and no. No. 4 was manufactured using the manufacturing method described above. Sample No. 3 and no. 4 is an example of the present disclosure. In addition, sample No. 1 and no. 2 is a conventional cermet sintered body and is a comparative example.

Each sample No. 1~No. Regarding the surface area and internal area of No. 4, the average particle diameter and area ratio of the first hard phase and the second hard phase were calculated using the analysis method described above. In this calculation, the lower limit of the measurement target was set to 0.1 μm as described above. The results are shown in Table 1.

Sample No. The average particle size of the first hard phase in Sample No. 1 was 0.22 μm in the surface region and 0.31 μm in the internal region. Sample No. The average particle size of the first hard phase in No. 2 was 0.29 μm in the inner region. Sample No. The average particle size of the first hard phase in Sample No. 3 was 0.29 μm in the surface region and 0.3 μm in the internal region. Sample No. The average particle size of the first hard phase in Sample No. 4 was 0.26 μm in the surface region and 0.34 μm in the internal region.

Sample No. The area ratio of the first hard phase in Sample No. 1 was 12 area % in the surface area and 36.8 area % in the internal area. Sample No. The area ratio of the first hard phase in No. 2 was 0 area % in the surface area and 4.3 area % in the internal area. Sample No. The area ratio of the first hard phase in Sample No. 3 was 28.7 area % in the surface area and 30.1 area % in the internal area. Sample No. The area ratio of the first hard phase in Sample No. 4 was 19 area % in the surface area and 51 area % in the internal area.

The ratio of the average particle size of the first hard phase in the surface area to the average particle size of the first hard phase in the internal area is as follows: Sample No. 1 is 0.7, sample No. 3 is 0.95, sample No. 4 was 0.76. The ratio is determined by surface average particle size/internal average particle size.

Sample No. The average particle size of the second hard phase in Sample No. 1 was 0.95 μm in the surface region and 0.48 μm in the internal region. Sample No. The average particle size of the second hard phase in Sample No. 2 was 0.91 μm in the surface region and 0.85 μm in the internal region. Sample No. The average particle size of the second hard phase in Sample No. 3 was 0.41 μm in the surface region and 0.51 μm in the internal region. Sample No. The average particle size of the second hard phase in Sample No. 4 was 0.36 μm in the surface region and 0.58 μm in the internal region.

Sample No. The area ratio of the second hard phase in Sample No. 1 was 88 area % in the surface area and 63.2 area % in the internal area. Sample No. The area ratio of the second hard phase in No. 2 was 100 area % in the surface area and 95.7 area % in the internal area. Sample No. The area ratio of the second hard phase in No. 3 was 71.3 area % in the surface area and 69.9 area % in the internal area. Sample No. The area ratio of the second hard phase in No. 4 was 81 area % in the surface area and 49 area % in the internal area.

The ratio of the average particle size of the second hard phase in the surface area to the average particle size of the second hard phase in the internal area is as follows: Sample No. 1 is 1.98, sample no. 2 is 1.07, sample No. 3 is 0.8, sample No. 4 was 0.62.

In addition, the average particle diameter of the entire hard phase including the first hard phase and the second hard phase is that of sample No. Sample No. 1 was 0.64 μm in the surface region, 0.39 μm in the internal region, and sample No. Sample No. 2 was 0.91 μm in the surface region and 0.85 μm in the internal region. Sample No. 3 was 0.36 μm in the surface region and 0.42 μm in the internal region. 4 was 0.34 μm in the surface area and 0.46 μm in the internal area.

In this way, sample No. which is an example. 3 and no. In No. 4, the average particle diameter d _2in of the second hard phase in the internal region and the average particle diameter d _2sf of the second hard phase in the surface region are both 0.35 μm or more and 0.6 μm or less. In addition, sample No. which is an example. 3, the area ratio S _2in of the second hard phase to the entire hard phase in the internal region and the area ratio S _2sf of the second hard phase to the entire hard phase in the surface area are both 50 area % or more and 80 area % or less. It is.

In addition, sample No. which is an example. 3 and no. In No. 4, the average particle diameter d _1in of the first hard phase in the internal region and the average particle diameter d _1sf of the first hard phase in the surface region are both 0.25 μm or more and 0.35 μm or less. In addition, sample No. which is an example. 3, the area ratio S _1in of the first hard phase to the entire hard phase in the internal region and the area ratio S _1sf of the first hard phase to the entire hard phase in the surface area are both 20 area % or more and 35 area % or less. It is.

From these results, sample No. 3 and no. Sample No. 4 is a comparative example. 1, No. It can be seen that the second hard phase in the surface region is finer than that in Sample No. 2. After that, sample No. which is an example. 3 and no. Sample No. 4 is a comparative example. 1, No. It can be seen that compared to No. 2, the difference in particle size between the hard phase between the surface region and the internal region, specifically, the first hard phase and the second hard phase, is small.

Sample No. 1~No. Regarding No. 4, the thermal conductivity, Young's modulus, coefficient of thermal expansion, hardness, and anti-destructive strength were measured. The results are shown in Table 2.

Note that the thermal conductivity (λ) may be determined in accordance with JIS R 1611. Young's modulus (E) may be determined in accordance with ISO14577. The coefficient of thermal expansion (α) may be determined in accordance with JIS R 1618. The hardness may be determined in accordance with JIS R 1610. The anti-destructive strength may be determined in accordance with JIS R 1601. A strength test piece was prepared as described below and used for the bending strength test of the surface region and internal region. Each surface of a rectangular parallelepiped sintered body of an internal strength test piece (dimensions: 4 mm * 5 mm * 40 mm) was ground by 0.5 mm. A surface strength test piece (dimensions: 4 mm * 5 mm * 40 mm) was ground by 0.5 to 1 mm from each surface of the rectangular parallelepiped except for the tension surface. Furthermore, in order to have the same shape as the tool surface, the tension surface of each strength test piece was blasted and polished by several μm to 10 μm to produce a test piece of 3 mm * 4 mm * 40 mm.

Further, the thermal shock strength (R _1c ) was calculated from the obtained thermal conductivity (λ), Young's modulus (E), thermal expansion coefficient (α), and anti-destructive strength (σ). Thermal shock strength R _1c is obtained by the formula R _1c = (λσ)/Eα. Further, "ΔHV20" shown in Table 2 is the absolute value |H1-H2| of the difference between the hardness H1 in the surface region and the hardness H2 in the internal region. In addition, "HV20" means hardness when measured with a test force of 20 kgf.

Sample No. which is an example. In No. 3, the anti-destructive strength σ1 in the surface region was 2449 MPa, and the anti-destructive strength σ2 in the internal region was 2512 MPa. In addition, sample No. In No. 3, the strength ratio (σ1/σ2) of anti-analytical strength σ1 to anti-analytical strength σ2 was 0.97. Note that the anti-destructive strength σ1 is the surface strength, and the anti-destructive strength σ2 is the internal strength.

In addition, sample No. which is an example. In No. 4, the anti-destructive strength σ1 in the surface region was 2450 MPa, and the anti-destructive strength σ2 in the internal region was 2350 MPa. In addition, sample No. In No. 4, the strength ratio (σ1/σ2) of anti-analytical strength σ1 to anti-analytical strength σ2 was 1.04.

In this way, sample No. which is an example. 3 and no. 4, the anti-resistance strength σ1 in the surface region and the anti-resistance strength σ2 in the internal region are both 2300 MPa or more, and the strength ratio (σ1/σ2) of the anti-resistance strength σ1 to the anti-resistance strength σ2 is: It is 0.8 or more. From this result, sample No. which is an example. 3 and no. It can be seen that in No. 4, the strength in the inner region is relatively high, and the strength in the surface region is also as high as the strength in the inner region.

In addition, sample No. which is an example. In No. 3, the hardness H1 in the surface region was 1531 HV20, and the hardness H2 in the internal region was 1495 HV20. Further, ΔHV20 was 36HV.

In this way, sample No. which is an example. In No. 3, the hardness H1 in the surface region and the hardness H2 in the internal region are both 1450 HV or more, and the absolute value of the difference between the hardness H1 and the hardness H2 |H1-H2| is 50 or less. From this result, sample No. which is an example. 3, it can be seen that the hardness in the surface region is comparable to the hardness in the internal region.

In addition, sample No. which is an example. In No. 4, the hardness H1 in the surface region was 1560HV20, and the hardness H2 in the internal region was 1450HV20. Further, ΔHV20 was 110HV.

In addition, sample No. which is an example. No. 3 had a thermal shock strength of 9783 in the surface region and a thermal shock strength of 10105 in the internal region. In addition, sample No. which is an example. No. 4 had a thermal shock strength of 9795 in the surface region and a thermal shock strength of 9549 in the internal region. On the other hand, sample No., which is a comparative example. No. 1 had a thermal shock strength of 5922 in the surface region and a thermal shock strength of 10309 in the internal region. In addition, sample No. 1, which is a comparative example. No. 2 had a thermal shock strength of 7970 in the surface region and a thermal shock strength of 8274 in the internal region. In this way, sample No. which is an example. 3 and no. Sample No. 4 is a comparative example. 1 and no. It can be seen that the thermal shock strength in the surface region is improved compared to No. 2.

Also, each sample No. 1~No. A fracture resistance test was conducted on No. 4. The conditions for the fracture resistance test are as follows.

<Failure resistance test (turning)>
Work material: S45C (25mm width groove x 4)
Cutting speed: 250m/min
Feed: 0.25mm/rev
Depth of cut: 0.5mm
Cutting condition: Wet evaluation method: Number of impacts until breakage (times)

As shown in Table 2, the number of impacts until breakage was the same for Sample No., which is a comparative example. 1 is 8464 times, and sample No. 2 was 9141 times, whereas Sample No. 2, which is an example, had 9141 times. 3 is sample No. 11,040 times. 4 was 10,070 times. From this result, sample No. which is an example. 3 and no. Sample No. 4 is a comparative example. 1 and no. It can be seen that the fracture resistance is improved compared to No. 2.

FIG. 5 shows sample No. 1, which is a comparative example. 1 and sample No. 1 which is an example. 3 is a graph showing the anti-resistance strength in the surface area and the internal area for No. 3. In FIG. 5, the vertical axis represents the strength ratio when the anti-destructive strength in the internal region is taken as 100%. Further, FIG. 6 shows sample No. 6, which is a comparative example. 1 and sample No. 1 which is an example. 3 is a graph showing the thermal shock strength of No. 3. In FIG. 6, sample No. The vertical axis shows the strength ratio when the thermal shock strength in the surface area of No. 1 is taken as 100%.

As shown in FIG. 5, sample No. 1, which is an example, Sample No. 3 is a comparative example. It can be seen that the difference between the anti-destructive strength in the surface region and the anti-destructive strength in the internal region is small compared to No. 1. In addition, as shown in FIG. 6, sample No. 1, which is an example, Sample No. 3 is a comparative example. It can be seen that the thermal shock strength in the surface region is improved compared to No. 1. Specifically, sample No. which is an example. Sample No. 3 is a comparative example. It can be seen that the thermal shock strength in the surface area is approximately 1.65 times higher than that of No. 1.

As described above, the cermet sintered body according to the embodiment (as an example, the base body 2) has a first hard phase (as an example, the first hard phase 5a) containing TiCN as a main component, and A bond containing a second hard phase (for example, second hard phase 5b) that is a composite carbonitride solid solution of at least one of

Group

5 and 6 metals and Ti, at least one of Co and Ni, and W. phase (as an example, a bonded phase 6). The average particle diameter d _2in of the second hard phase in the internal region and the average particle diameter d _2sf of the second hard phase in the surface region are both 0.35 μm or more and 0.6 μm or less. The intensity σ1 in the surface region and the intensity σ2 in the internal region are both 2300 MPa or more, and the intensity ratio of σ1 to σ2 (σ1/σ2) is 0.8 or more.

Therefore, according to the cermet sintered body according to the embodiment, the thermal shock resistance on the surface can be improved.

Note that the shape of the cermet tool 1 shown in FIG. 1 is just an example, and does not limit the shape of the cermet tool according to the present disclosure. A cermet tool according to the present disclosure includes, for example, a rod-shaped main body having a rotating shaft and extending from a first end to a second end, a cutting blade located at the first end of the main body, and a second end of the main body from the cutting blade. It may have a groove extending spirally toward the side.

Furthermore, although an example in which the cermet sintered body is used as a tool has been described here, the use of the cermet sintered body according to the present disclosure is not limited to tools.

Further effects and modifications can be easily deduced by those skilled in the art. Therefore, the broader aspects of the invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various changes may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

1 Cermet tool 2 Base 3 Covering layer 5 Hard phase 5a First hard phase 5b Second hard phase 6 Bonding phase 21 Through hole 70 Holder 73 Pocket 75 Screw 100 Cutting tool

Claims

A cermet sintered body,
a first hard phase mainly composed of TiCN;
a second hard phase that is a composite carbonitride solid solution of Ti and at least one metal of Groups 4, 5 and 6 of the periodic table;
a binder phase containing at least one of Co and Ni and W;
The average particle size d 2in of the second hard phase in the internal region and the average particle size d 2sf of the second hard phase in the surface area are both 0.35 μm or more and 0.6 μm or less,
The strength σ1 in the surface region and the strength σ2 in the internal region are both 2300 MPa or more, and the strength ratio (σ1/σ2) of the σ1 to the σ2 is 0.8 or more. Concretion.
The area ratio S 2in of the second hard phase to the entire hard phase in the internal region and the area ratio S 2sf of the second hard phase to the entire hard phase in the surface area are both 50 area % or more and 80 area % or less. The cermet sintered body according to claim 1.
The average particle size d 1in of the first hard phase in the internal region and the average particle size d 1sf of the first hard phase in the surface area are both 0.25 μm or more and 0.35 μm or less,
The area ratio S 1in of the first hard phase to the entire hard phase in the internal region and the area ratio S 1sf of the first hard phase to the entire hard phase in the surface area are both 20 area % or more and 35 area %. The cermet sintered body according to claim 1, which is as follows.
The hardness H1 in the surface region and the hardness H2 in the internal region are both 1450 HV or more,
The cermet sintered body according to claim 1, wherein the absolute value of the difference between the H1 and the H2 |H1−H2| is 50 or less.
The cermet sintered body according to any one of claims 1 to 4,
At least one metal element selected from Groups 4, 5 and 6 of the periodic table, Al and Si, and at least one metal element selected from C, N and O, located on at least a part of the surface of the cermet sintered body. A cermet tool comprising one or more coating layers comprising one type of nonmetallic element.
a holder extending from a first end toward a second end and having a pocket on a side of the first end;
A cutting tool comprising: the cermet tool according to claim 5 located in the pocket.