Cermet tools and cutting tools

Abstract

A cermet tool according to the present disclosure has a base comprising a cermet sintered body containing a hard phase containing at least a Ti carbonitride, and a bonding phase containing Co and / or Ni. In a cermet tool according to an aspect of the present disclosure, the hard phase and the bonding phase further contain Cr and W, the strength I800 at 800℃ is greater than or equal to 1400 MPa, and the ratio I800 / Ir of the intensity I800 to the intensity Ir at room temperature is greater than or equal to 0.9.

Description

Technical Field

[0001] The present disclosure relates to cermet tools and cutting tools.

Background Art

[0002] As a substrate for members that require wear resistance, slidability, and chipping resistance, such as cutting tools, wear-resistant members, and sliding members, cermets mainly composed of titanium (Ti) are widely used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A cermet tool according to one aspect of the present disclosure is a cermet tool having a substrate made of a cermet sintered body containing a hard phase containing at least a carbonitride of Ti and a binder phase containing at least one of Co and Ni. A cermet tool according to one aspect of the present disclosure further contains Cr and W in the hard phase and the binder phase, and the strength I 800 at 800 °C is 1400 MPa or more, and the ratio I r of the strength I 800 at 800 °C to the strength I 800 / I r at room temperature is 0.9 or more.

Brief Description of the Drawings

[0005]

Figure 1

Figure 2

Figure 3

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Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0006] Hereinafter, embodiments (hereinafter referred to as "embodiments") for implementing the cermet tool and the cutting tool according to the present disclosure will be described in detail with reference to the drawings. Note that the cermet tool and the cutting tool according to the present disclosure are not limited by this embodiment. Also, the embodiments can be appropriately combined as long as the processing contents do not conflict. In addition, the same parts in the following embodiments are denoted by the same reference numerals, and overlapping descriptions are omitted.

[0007] In addition, in the embodiments described below, expressions such as "constant", "orthogonal", "perpendicular", or "parallel" may be used, but these expressions do not necessarily require strict "constant", "orthogonal", "perpendicular", or "parallel". That is, each of the above expressions is assumed to allow for deviations such as manufacturing accuracy and installation accuracy.

[0008] Cermets have room for further improvement in that they are vulnerable to thermal shock and prone to defects. Therefore, there is an expectation for the provision of cermet tools and cutting tools with high defect resistance.

[0009] <Cermet tool> FIG. 1 is a perspective view showing an example of a cermet tool according to an embodiment. Further, FIG. 2 is a side sectional view showing an example of the cermet tool 1 according to the embodiment. As shown in FIGS. 1 and 2, the cermet tool 1 according to the embodiment includes a substrate 2, a coating layer 3, and an intermediate layer 4.

[0010] (Substrate 2) The substrate 2 has, for example, a hexahedral shape in which the shapes of the upper surface and the lower surface (the surface intersecting the Z axis shown in FIG. 1) are parallelograms.

[0011] One corner portion of the substrate 2 functions as a cutting edge portion. The cutting edge portion has a first surface (for example, the upper surface) and a second surface (for example, a side surface) connected to the first surface. In the embodiment, the first surface functions as a "rake surface" for scooping up the chips generated by cutting, and the second surface functions as a "flank surface". A cutting edge is located at at least a part of the ridge line where the first surface and the second surface intersect, and the cermet tool 1 cuts the workpiece by applying such a cutting edge to the workpiece.

[0012] A through hole 21 penetrating the substrate 2 vertically may be located at the center of the substrate 2. In this case, a screw 75 for attaching the cermet tool 1 to a holder 70 described later is inserted into the through hole 21 (see FIG. 7).

[0013] The substrate 2 is made of a cermet sintered body. The cermet sintered body contains a hard phase and a binder phase. The hard phase contains at least a carbonitride of Ti (TiCN). The binder phase contains at least one of Co and Ni.

[0014] The substrate 2 further contains Cr and W in the hard phase and the binder phase. The cermet tool 1 according to the embodiment has a strength I 800 of 1400 MPa or more at 800 °C, and a strength I r at room temperature with respect to the strength I 800 of the ratio I 800 / I r of 0.9 or more.

[0015] The substrate 2 having such a configuration can relatively increase the amount of W dissolved in the binder phase as compared with the case where the hard phase and the binder phase do not contain Cr. This will be described with reference to FIGS. 3 to 6.

[0016] FIGS. 3 and 4 are schematic diagrams for explaining the mechanism by which W in the binder phase dissolves into the hard phase in a cermet according to a reference example in which the hard phase and the binder phase do not contain Cr. FIGS. 5 and 6 are schematic diagrams for explaining the mechanism by which the dissolution of W in the binder phase into the hard phase is suppressed in the substrate 2 of the cermet tool 1 according to the embodiment.

[0017] During the sintering of the cermet, N desorbs from the hard particles 221X such as TiCN, and W in the binder phase 201X enters the desorbed portion (see FIG. 3), and a solid solution 222X composed of (Ti, M)CN (M is a metal element and contains at least W) is formed around the hard particles 221X (see FIG. 4). As a result, the amount of W in the binder phase decreases.

[0018] On the other hand, during the sintering of the substrate 2 according to the embodiment, Cr contained in the binder phase 201 binds to N in the hard particles 221 (see FIG. 5), and a solid solution 222 composed of (Ti, M)CN (M is a metal element and contains at least Cr) is formed around the hard particles 221 (see FIG. 6).

[0019] Thus, in the substrate 2 according to the embodiment, since the solid solution of W in the hard phase in the binder phase is suppressed, the amount of W in the binder phase relatively increases as compared with the reference example. By increasing the amount of W in the binder phase, the high-temperature hardness of the binder phase increases, and the high-temperature strength also increases. Therefore, according to the cermet tool 1 according to the embodiment, the defect resistance can be improved.

[0020] The substrate 2 may further contain at least one metal element selected from Group 4A elements, Group 5A elements, and Group 6A elements (excluding Ti, Cr, and W) of the periodic table and Si in the hard phase or the binder phase. For example, in addition to Ti, Cr, and W, the substrate 2 may contain Zr, V, Nb, Ta, Mo, etc.

[0021] The content of Cr in the hard phase Cr H may be 0.6% by mass or more and less than 2.5% by mass.

[0022] The content of Cr in the hard phase Cr H When it is 0.6% by mass or more, since the amount of Cr dissolved in the hard phase is ensured, the amount of W dissolved in the hard phase relatively decreases, and accordingly, the content of W in the binder phase increases. For this reason, when the content of Cr in the hard phase Cr H is 0.6% by mass or more, the high-temperature strength is likely to be improved. Also, when the content of Cr in the hard phase Cr H is less than 2.5% by mass, it is easy to avoid an excessive increase in the amount of solid solution in the hard phase, so the entire hard phase containing the solid solution is less likely to be coarsened, and the high-temperature strength is improved.

[0023] For this reason, the cermet tool 1 in which the content of Cr in the hard phase Cr H is 0.6% by mass or more and less than 2.5% by mass can preferably increase the high-temperature strength and preferably improve the defect resistance.

[0024] The content of W in the binder phase W Bis 0.8 mass% or more and may be less than 1.8 mass%.

[0025] The content of W in the binder phase, W B When it is 0.8 mass% or more, since the content of W in the binder phase is ensured, the high-temperature strength is likely to be improved. Also, the content of W in the binder phase, W B When it is less than 1.8 mass%, the binder phase is less likely to become brittle and the defect resistance is likely to be improved.

[0026] Therefore, the cermet tool 1 in which the content of W in the binder phase, W B is 0.8 mass% or more and less than 1.8 mass% can preferably increase the high-temperature strength and preferably improve the defect resistance.

[0027] The content of W in the hard phase, W H is 12.5 mass% or more and may be 13.47 mass% or less.

[0028] The content of W in the hard phase, W H When it is 12.5 mass% or more, the amount of solid solution in the hard phase is stably ensured. Therefore, the wear resistance of the hard phase is improved and the wear resistance of the entire cermet tool 1 is improved. Also, the content of W in the hard phase, W H When it is 13.47 mass% or less, it is easy to avoid an excessive increase in the amount of solid solution in the hard phase. Therefore, the defect resistance of the hard phase is improved and the defect resistance of the entire cermet tool 1 is improved. That is, when the content of W in the hard phase, W H is 12.5 mass% or more and 13.47 mass% or less, an appropriate amount of solid solution in the hard phase can be achieved, so that both the wear resistance and the defect resistance of the hard phase can be achieved.

[0029] The content of W in the hard phase, W H may be more than the content of W in the binder phase, W B The wear resistance of the entire cermet tool 1 is greatly affected by W in the hard phase rather than W in the binder phase. Therefore, WH is more than W B If it is more than that, the wear resistance of the cermet tool 1 as a whole can be increased without making the W content of the cermet tool 1 as a whole an excessive value.

[0030] The Cr content Cr in the bonding phase B may be more than 0.4% by mass and less than 0.9% by mass.

[0031] The Cr content Cr in the bonding phase B When it is more than 0.4% by mass, the effect of "suppressing the solid solution of W into the hard phase by binding to N in the hard phase" is more easily obtained. On the other hand, the Cr content Cr in the bonding phase B When it is less than 0.9% by mass, carbides of Cr are less likely to be formed in the bonding phase. As a result, the bonding phase is less likely to become brittle, so the defect resistance is likely to be improved.

[0032] Therefore, the cermet tool 1 in which the Cr content Cr in the bonding phase B is more than 0.4% by mass and less than 0.9% by mass can suitably increase the high-temperature strength and suitably improve the defect resistance.

[0033] The Cr content Cr in the bonding phase B may be less than the Cr content Cr in the hard phase. For example, when the W content W in the hard phase H is more than the W content W in the bonding phase H it is effective. When W B is relatively small, the influence of the solid solution of W in the bonding phase into the hard phase is large. Here, when Cr H is relatively large, the suppressing effect of the solid solution of W in the bonding phase into the hard phase is high. Also, when Cr H is relatively large, the suppressing effect of the solid solution of W in the bonding phase into the hard phase is high. Also, when both values of Cr H and Cr B are high, the suppressing effect of the solid solution of W in the bonding phase into the hard phase is high, but as described above, carbides of Cr are likely to be formed in the bonding phase. When Cr H is relatively large and Cr BWhen it is relatively small, while the effect of suppressing the solid solution of W into the hard phase in the bonding phase can be obtained, the effect of suppressing the formation of carbides of Cr in the bonding phase is also easily obtained.

[0034] The content of Cr in the hard phase Cr H With respect to the content of Cr in the bonding phase Cr B The ratio of Cr B / Cr H may be more than 0.33 and 1 or less. Cr B / Cr H The cermet tool 1 in which Cr / Cr is within the above range has a good balance of properties and high defect resistance and high-temperature strength.

[0035] (Coating layer 3) The coating layer 3 is coated on the substrate 2 for the purpose of improving, for example, the wear resistance, heat resistance, etc. of the substrate 2. In FIG. 2, an example where the coating layer 3 entirely covers the surface of the substrate 2 is shown, but the coating layer 3 does not necessarily have to cover the entire surface of the substrate 2. The coating layer 3 may be located at least on a part of the surface of the substrate 2. When the coating layer 3 is located on the first surface (here, the upper surface) of the substrate 2, the wear resistance and heat resistance of the first surface are high. When the coating layer 3 is located on the second surface (here, the side surface) of the substrate 2, the wear resistance and heat resistance of the second surface are high.

[0036] The coating layer 3 may be composed of, for example, at least one metal element selected from Group 4A, Group 5A, and Group 6A elements of the periodic table and Al and Si, and at least one non-metal element selected from C, N, and O. In such a configuration, the oxidation resistance of the coating layer 3 is improved. Thereby, the wear resistance of the coating layer 3 is further improved. The coating layer 3 may be a single layer. Also, the cermet tool 1 may have a coating layer 3 laminated in layers.

[0037] <Cutting tool> Next, the configuration of a cutting tool including the above-described cermet tool 1 will be described with reference to FIG. 7. FIG. 7 is a front view showing an example of a cutting tool according to an embodiment.

[0038] As shown in Fig. 7, the cutting tool 100 according to the embodiment includes a cermet tool 1 and a holder 70 for fixing the cermet tool 1.

[0039] The holder 70 is a rod-shaped member extending from the first end (the upper end in Fig. 7) to the second end (the lower end in Fig. 7). The holder 70 is made of, for example, steel or cast iron. In particular, it is preferable to use steel with high toughness among these members.

[0040] The holder 70 has a pocket 73 at the end on the first end side. The pocket 73 is a portion where the cermet tool 1 is mounted, and has a seating surface intersecting the rotational direction of the workpiece and a restraining side surface inclined with respect to the seating surface. A screw hole for screwing a screw 75 described later is provided in the seating surface.

[0041] The cermet tool 1 is located in the pocket 73 of the holder 70 and is mounted on 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 this screw 75 is inserted into the screw hole formed in the seating surface of the pocket 73 to screw the screw portions together. Thereby, the cermet tool 1 is mounted on the holder 70 such that the cutting edge portion protrudes outward from the holder 70.

[0042] In the embodiment, a cutting tool used for so-called turning is exemplified. Examples of turning include, for example, internal diameter machining, external diameter machining, and grooving. Note that the cutting tool is not limited to those used for turning. For example, the cermet tool 1 may be used for a cutting tool used for milling. Examples of cutting tools used for milling include, for example, face mills such as flat mills, front mills, side mills, and groove-cutting mills, single-edge end mills, multi-edge end mills, taper-edge end mills, ball end mills, and the like.

[0043] (Manufacturing method) Next, a manufacturing method of the substrate 2 included in the cermet tool 1 will be described.

[0044] First, a plurality of raw material powders are mixed to prepare a mixed powder. The raw material powders include at least one of TiCN powder, WC powder, CrC powder, carbide powders of Group 4, 5, and 6 metals in the periodic table (excluding TiCN, WC, and Cr3C2), nitride powders, and carbonitride powders, metal Co powder or metal Ni powder, and metal W powder and WC 1-x (0 < x ≦ 1) powder, and at least one of them is included. The raw material powders may optionally contain carbon powder. The average particle size of the TiCN powder is 0.1 μm or more and 1.2 μm or less, particularly 0.3 μm or more and 0.9 μm or less. The average particle size of the WC powder is 0.1 μm or more and 2.5 μm or less. The average particle size of the Cr3C2 powder is 2 μm or more and 4 μm or less. The average particle size of the metal Co powder or metal Ni powder is 0.5 μm or more and 5 μm or less. The average particle size of metal W powder and WC 1-x (0 < x ≦ 1) powder of at least one kind is 3 μm or more and 15 μm, and the content is 1 mass% or more and 20 mass% or less. A predetermined amount of MO2C powder with an average particle size of 0.5 μm or more and 5 μm or less may be further added to the mixed powder.

[0045] In this embodiment, as at least one of carbide powders, nitride powders, and carbonitride powders of Group 4, 5, and 6 metals in the periodic table other than TiCN, TiC powder, TiN powder, WC powder, NbC powder, MnCo3 powder, TaC powder, VC powder, and ZrC powder with an average particle size of 0.1 μm or more and 3 μm or less may be applied.

[0046] The adjustment of the mixed powder is carried out by adding a binder, a solvent, etc. to the above raw material powders and mixing them by a known mixing method such as a ball mill, a vibration mill, a jet mill, or an attritor mill. When powder mixing by an attritor mill is used, the raw material powders are pulverized and the particle size becomes smaller, but since the metal powders have high ductility, they tend to be difficult to be pulverized. Then, this mixed powder is formed into a molded body of a predetermined shape by a known molding method such as press molding, extrusion molding, or injection molding.

[0047] Subsequently, the above-formed body is fired in a vacuum or an inert gas atmosphere. In this embodiment, by firing under the following conditions, a cermet having the above-described predetermined structure can be produced. First, (a) the temperature is raised from room temperature to 450°C and held for 0.5 hours or more and 2 hours or less to perform degreasing. Subsequently, (b) the temperature is further raised from 450°C to 1000°C or more and 1100°C or less. Subsequently, (c) in a vacuum, the temperature is raised from a temperature of 1000°C or more and 1100°C or less to a firing temperature T1 of 1280°C or more and 1380°C or less at a heating rate a of 0.1°C / min or more and 2°C / min or less. Subsequently, (d) in a vacuum or an inert gas atmosphere of 30 Pa or more and 20000 Pa or less, the temperature is raised from the firing temperature T1 to a firing temperature T2 of 1500°C or more and 1600°C or less at a heating rate b of 4°C / min or more and 15°C / min or less. Subsequently, (e) it is held at the firing temperature T2 for 0.5 hours or more and 2 hours or less in a vacuum or an inert gas atmosphere of 30 Pa or more and 20000 Pa or less. Thereafter, (f) it is fired under a firing condition of cooling at a cooling rate e of 5°C / min or more and 40°C / min or less in a vacuum or an inert gas atmosphere of 30 Pa or more and 20000 Pa or less.

Example

[0048] Hereinafter, examples of the present disclosure will be specifically described. Note that the present disclosure is not limited to the examples shown below.

[0049] A plurality of samples No. 1 to No. 10 having a substrate made of a cermet sintered body were produced by the above-described manufacturing method. Among samples No. 1 to No. 10, samples No. 3 to No. 8 are examples of the present disclosure. Also, samples No. 1, No. 2, No. 9, and No. 10 are comparative examples.

[0050] The blending amounts of various raw materials in each of samples No. 1 to No. 10 are as shown in FIG. 8. FIG. 8 is a table showing the blending amounts of various raw materials in samples No. 1 to No. 10.

[0051] As shown in Fig. 8, the Cr content at the time of compounding is lower for samples with a younger sample number. That is, the Cr content at the time of compounding is lowest for sample No. 1 (0 mass% in terms of the Cr3C2 content) and highest for sample No. 10 (4.646 mass% in terms of the Cr3C2 content). Also, the W content at the time of compounding is 13.495 mass% for the lowest sample No. 8 in terms of the WC and W contents and 15 mass% for samples No. 1 to No. 5 with the highest content, and is generally the same for samples No. 1 to No. 10.

[0052] Strength tests were conducted on the prepared samples Nos. 1 to No. 10. The shape of each sample was a test piece of 3 mm × 4 mm × 40 mm. The test pieces were produced by the press molding method and mirror-finished on the tensile surface. The strength test was carried out using a three-point bending test jig. The test speed (crosshead speed) was 0.5 mm / min, the span (distance between external supports) was 30 mm, and a load was applied until the test piece broke, and the load at the time of breakage was taken as the strength of that sample.

[0053] The strength tests were carried out in the air under temperature environments of room temperature (25°C) and 800°C.

[0054] Also, cutting tests were conducted on the prepared samples Nos. 1 to No. 10. Specifically, defect resistance tests and wear resistance tests were carried out on samples Nos. 1 to No. 10. For the defect resistance test, the end face of the work material was intermittently cut with a cutting depth of 0.5 mm, and the evaluation was made based on the number of impacts at the time when a defect occurred in the sample. For the wear resistance test, the evaluation was made based on the width (μm) of crater wear at the time when cutting was carried out for 32 minutes. The specific conditions for each test are as follows.

[0055] <Defect resistance test> Work material: S45C Cutting speed: 150 m / min Feed: 0.25 mm / rev Cutting depth: 0.5 mm Cutting state: Wet Evaluation method: Number of impacts until defect (times)

[0056] <Abrasion Resistance Test> Workpiece material: SCM435 Cutting speed: 250 m / min Feed: 0.2 mm / rev Depth of cut: 1.0 mm Cutting condition: Wet Evaluation method: Width (μm) of crater wear at the time of 32-minute cutting

[0057] Figure 9 is a table summarizing the results of various tests for Sample Nos. 1 to 10.

[0058] As shown in Figure 9, in Sample No. 1, the Cr content Cr in the hard phase H and the Cr content Cr in the binder phase B were both 0% by mass. That is, the hard phase and the binder phase of Sample No. 1 did not contain Cr. The W content W in the hard phase of Sample No. 1 H was 13.63% by mass, and the W content W in the binder phase B was 0.5% by mass.

[0059] In Sample No. 2, the Cr content Cr in the hard phase H was 0.42% by mass, the W content W in the hard phase H was 13.61% by mass, the Cr content Cr in the binder phase B was 0.3% by mass, and the W content W in the binder phase B was 0.66% by mass. Also, in Sample No. 2, Cr B / Cr H was 0.72.

[0060] In Sample No. 3, the Cr content Cr in the hard phase H was 0.53% by mass, the W content W in the hard phase H was 13.39% by mass, the Cr content Cr in the binder phase B was 0.33% by mass, and the W content W in the binder phase B was 0.88% by mass. Also, in Sample No. 3, Cr B / Cr Hwas 0.62.

[0061] In sample No. 4, the Cr content Cr in the hard phase H was 0.6 mass%, the W content W in the hard phase H was 13.47 mass%, the Cr content Cr in the binder phase B was 0.41 mass%, and the W content W in the binder phase B was 0.8 mass%. Also, in sample No. 4, Cr B / Cr H was 0.69.

[0062] In sample No. 5, the Cr content Cr in the hard phase H was 0.73 mass%, the W content W in the hard phase H was 13.17 mass%, the Cr content Cr in the binder phase B was 0.42 mass%, and the W content W in the binder phase B was 1.1 mass%. Also, in sample No. 5, Cr B / Cr H was 0.57.

[0063] In sample No. 6, the Cr content Cr in the hard phase H was 1.7 mass%, the W content W in the hard phase H was 12.87 mass%, the Cr content Cr in the binder phase B was 0.6 mass%, and the W content W in the binder phase B was 1.4 mass%. Also, in sample No. 6, Cr B / Cr H was 0.35.

[0064] In sample No. 7, the Cr content Cr in the hard phase H was 2.03 mass%, the W content W in the hard phase H was 12.52 mass%, the Cr content Cr in the binder phase B was 0.7 mass%, and the W content W in the binder phase B was 1.75 mass%. Also, in sample No. 7, Cr B / CrH was 0.34.

[0065] In sample No. 8, the Cr content in the hard phase was H is 2.37 mass%, and the W content in the hard phase is W H is 12.5 mass%, and the Cr content in the binder phase is Cr B is 0.8 mass%, and the W content in the binder phase is W B In sample No. 8, Cr was 1.77 mass%. B / Cr H was 0.34.

[0066] In sample No. 9, the Cr content in the hard phase was H is 2.7 mass%, and the W content in the hard phase is W H is 12.45 mass%, and the Cr content in the binder phase is Cr B is 0.9 mass%, and the W content in the binder phase is W B In sample No. 9, Cr was 1.82 mass%. B / Cr H The value of the Cr carbide in the binder phase of sample No. 9 was 0.33.

[0067] In sample No. 10, the Cr content in the hard phase was H is 3.03 mass%, and the W content in the hard phase is W H is 12.42 mass%, and the Cr content in the binder phase is Cr B is 1 mass%, W content in the binder phase W B In sample No. 10, Cr was 1.85 mass%. B / Cr H The value of the Cr carbide in the binder phase of sample No. 10 was 0.33.

[0068] Cr content in hard phase Cr H As the value of W increases, the W content in the binder phase increases. B increases, and the W content in the hard phase W HThese results indicate that the presence of Cr suppresses the solid solution of W into the hard phase.

[0069] Samples No. 4 to No. 8 have different Cr contents in the hard phase. H The W content in the binder phase is 0.6 mass % or more and less than 2.5 mass %. B The Cr content in the binder phase of Samples No. 4 to No. 8 is 0.8 mass % or more and less than 1.8 mass %. B The Cr content in the hard phase of samples No. 3 to No. 8 is more than 0.4 mass% and less than 0.9 mass%. H Cr content in the binder phase Cr B The ratio of Cr B / Cr H is greater than 0.33 and less than 1.

[0070] The results of the strength test for sample No. 3 were strength at room temperature (hereinafter referred to as "room temperature strength I"). r ") is 1556 MPa, and the strength at 800°C (hereinafter referred to as "high temperature strength I"). 800 ") was 1503 MPa. Also, the room temperature strength I r High temperature strength I 800 Ratio I 800 / I r The result of the chipping resistance test (number of impacts) of sample No. 3 was 8,367 times, and the result of the wear resistance test (crater wear width) was 48 μm.

[0071] The strength test results for sample No. 4 were: room temperature strength I r is 1469 MPa, and the high temperature strength I 800 is 14441 MPa, and I 800 / I r The result of the chipping resistance test (number of impacts) of Sample No. 4 was 9782 times, and the result of the wear resistance test (crater wear width) was 40 μm.

[0072] The results of the strength test for Specimen No. 5 showed that the room temperature strength I r was 1807 MPa, the high temperature strength I 800 was 1717 MPa, and I 800 / I r was 0.95. Also, the result of the defect resistance test (number of impacts) for Specimen No. 5 was 11,460 times.

[0073] The results of the strength test for Specimen No. 6 showed that the room temperature strength I r was 1754 MPa, the high temperature strength I 800 was 1706 MPa, and I 800 / I r was 0.97. Also, the result of the defect resistance test (number of impacts) for Specimen No. 6 was 17,461 times, and the result of the wear resistance test (crater wear width) was 29 μm.

[0074] The results of the strength test for Specimen No. 7 showed that the room temperature strength I r was 1896 MPa, the high temperature strength I 800 was 1801 MPa, and I 800 / I r was 0.95. Also, the result of the defect resistance test (number of impacts) for Specimen No. 7 was 16,867 times, and the result of the wear resistance test (crater wear width) was 32 μm.

[0075] The results of the strength test for Specimen No. 8 showed that the room temperature strength I r was 1852 MPa, the high temperature strength I 800 was 1704 MPa, and I 800 / I r was 0.92. Also, the result of the defect resistance test (number of impacts) for Specimen No. 8 was 15,066 times, and the result of the wear resistance test (crater wear width) was 43 μm.

[0076] Next, the test results for Specimens No. 1, No. 2, No. 9, and No. 10, which are comparative examples, will be described.

[0077] The results of the strength test for Specimen No. 1 showed that the room temperature strength I r was 1080 MPa, the high temperature strength I800 was 918 MPa, and I 800 / I r was 0.85. Also, the result (number of impact times) of the defect resistance test for Sample No. 1 was 7451 times, and the result (crater wear width) of the wear resistance test was 61 μm.

[0078] The result of the strength test for Sample No. 2 was that the room temperature strength I r was 1492 MPa, and the high temperature strength I 800 was 1313 MPa, and I 800 / I r was 0.88. Also, the result (number of impact times) of the defect resistance test for Sample No. 2 was 7704 times.

[0079] The result of the strength test for Sample No. 9 was that the room temperature strength I r was 1261 MPa, and the high temperature strength I 800 was 1082 MPa, and I 800 / I r was 0.86. Also, the result (number of impact times) of the defect resistance test for Sample No. 9 was 7652 times.

[0080] The result of the strength test for Sample No. 10 was that the room temperature strength I r was 1464 MPa, and the high temperature strength I 800 was 1252 MPa, and I 800 / I r was 0.86. Also, the result (number of impact times) of the defect resistance test for Sample No. 10 was 7640 times.

[0081] Samples No. 3 to No. 8, which are examples, all had a high temperature strength I 800 of 1400 MPa or more, and the ratio of the high temperature strength I r to the room temperature strength I 800 of I 800 / I ris 0.9 or more. Samples No. 3 to No. 8 having such characteristics can perform cutting of a work material while maintaining high strength from room temperature to high temperature. This is also clear from the results of the defect resistance test and the wear resistance test. That is, it can be seen that Samples No. 3 to No. 8 which are examples have higher defect resistance and higher wear resistance than Samples No. 1, No. 2, No. 9, and No. 10 which are comparative examples. Also, the content of Cr in the hard phase Cr H Samples No. 4 to No. 8 in which is 0.6 mass% or more and less than 2.5 mass% have a content of Cr in the hard phase Cr H Compared with Sample No. 3 in which is less than 0.6 mass%, the defect resistance is significantly improved and the wear resistance is also improved. In particular, Sample No. 6 was excellent in both defect resistance and wear resistance compared to other samples. As is clear from this result, by setting the content of Cr in the hard phase Cr H to be more than 0.8 mass% and less than 2 mass%, it is possible to obtain a cermet tool particularly excellent in defect resistance and wear resistance.

[0082] As described above, the cermet tool according to the embodiment (as an example, cermet tool 1) is a cermet tool having a substrate (as an example, substrate 2) made of a cermet sintered body containing a hard phase containing at least a carbonitride of Ti and a binder phase containing at least one of Co and Ni. The cermet tool according to the embodiment contains Cr and W in the hard phase and the binder phase, and the strength I at 800 ° C 800 is 1400 MPa or more, and the strength I at room temperature r The ratio I of the strength I to 800 is 0.9 or more. 800 / I r

[0083] Therefore, according to the cermet tool according to the embodiment, since the high-temperature strength is high and it is resistant to thermal shock, it is excellent in defect resistance.

[0084] 1 is merely an example and does not limit the shape of the cermet tool according to the present disclosure. The cermet tool according to the present disclosure may have, for example, a rod-shaped main body having a rotation axis and extending from a first end to a second end, a cutting edge located at the first end of the main body, and a groove extending spirally from the cutting edge toward the second end of the main body.

[0085] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0086] 1 Cermet tools 2 Base 3 Covering layer 4. Middle class 21 Through hole 70 Holder 73 Pocket 75 screws 100 cutting tools 201 Bonded phase 221 Hard particles 222 Solid solution

Claims

1. In a cermet tool having a substrate made of a cermet sintered body containing a hard phase containing at least a carbonitride of Ti and a binder phase containing at least one of Co and Ni, the hard phase and the binder phase further contain Cr and W, and the content CrB of Cr in the binder phase is less than the content CrH of Cr in the hard phase, The strength I at 800 °C ８００ is 1400 MPa or more, and the strength I at room temperature ｒ with respect to the strength I ８００ ratio I ８００ / I ｒ is 0.9 or more, a cermet tool.

2. The content of Cr in the hard phase, Cr Ｈ is a cermet tool according to claim 1, which is 0.6% by mass or more and less than 2.5% by mass.

3. The content of W in the hard phase, W Ｈ is more than the content of W in the binder phase, W Ｂ The cermet tool according to claim 1.

4. The content Cr in the hard phase Ｈ The content Cr in the binder phase relative to Ｂ The ratio Cr Ｂ / Cr Ｈ is more than 0.33 and 1 or less. The cermet tool according to claim 1

5. On at least a part of the surface of the substrate, there is located one layer or two or more coating layers composed of at least one metal element selected from Group 4A, Group 5A and Group 6A of the periodic table and Al and Si, and at least one non-metal element selected from C, N and O. The cermet tool according to Claim 1.

6. A holder extending from a first end to a second end and having a pocket on the first end side, and the cermet tool according to any one of Claims 1 to 5 located in the pocket. A cutting tool provided with the same.

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