JP6757519B2 - Composite members and cutting tools - Google Patents

Description

The present invention relates to a composite member and a cutting tool having excellent joint strength at a joint portion, and more particularly to a composite member obtained by joining a WC-based cemented carbide and a WC-based cemented carbide, and further to a cutting tool composed of the composite member. ..

Conventionally, WC-based cemented carbide, TiCN-based cermet, cBN sintered body and the like are well known as tool materials, but in recent years, tool materials are not formed from a single material but as a composite member. It has been proposed to form.

For example, Patent Document 1 describes a first joint body in which a cermet sintered body is used as a first material to be joined and a cBN sintered body or a diamond sintered body is used as a second material to be joined. A bonding material 2 (for example, Ti, Co, Ni) that does not generate a liquid phase at a temperature lower than 1000 ° C. is bonded between the material to be bonded and the second material to be bonded, and the bonding is performed at a pressure of 0.1 MPa to 200 MPa. It has been proposed to carry out by energizing and heating while pressurizing with, and the bonded body obtained by this is a joint layer even if the temperature of the brazing material exceeds the temperature at which the brazing material forms a liquid phase during cutting. Since the joint strength does not decrease, it is said to be suitable as a high-speed cutting tool or a CVD coating cutting tool.

Further, in Patent Document 2, in a bonded body in which a super hard alloy sintered body is used as a first material to be bonded and a cBN sintered body is used as a second material to be bonded, the first material to be bonded and the first material to be bonded are described. Between the two materials to be joined, at least two surfaces including the back surface and the bottom surface of the second material to be joined are joined via the joint material 3 containing titanium (Ti) to and the second material to be joined. A titanium nitride (TiN) compound layer having a thickness of 10 to 300 nm is formed at the interface with the bonding material, and the thickness of the bonding layer on the back surface is made thinner than the thickness of the bonding layer on the bottom surface to increase the bonding strength. It has been proposed to obtain joints such as expensive cutting tools.

Further, Patent Document 3 describes a cBN sintered body containing 20 to 100% by mass of cBN, carbides of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W, carbides and mutual solid solutions thereof. Hard phase consisting of at least one selected from the group consisting of: 50 to 97% by mass, and binding phase containing at least one selected from the group consisting of Co, Ni and Fe as a main component as a balance: 3 to In a composite with a cemented carbide consisting of 50% by mass, a bonding layer is provided between the cBN sintered body and the cemented carbide, the bonding layer is composed of a ceramic phase and a metal phase, and further, the bonding layer It has been proposed to increase the bonding strength of the composite by setting the thickness to 2 to 30 μm.

Japanese Unexamined Patent Publication No. 2009-241236 Japanese Unexamined Patent Publication No. 2012-11187 Japanese Unexamined Patent Publication No. 2014-131819

The composite material or cutting tool made of the composite material proposed in Patent Documents 1 to 3 exhibits a certain level of performance in cutting under normal conditions, but for example, a high feed and a high depth of cut in which a high load acts on the cutting edge. Under heavy cutting conditions, the joint strength is not yet sufficient, and there is a risk of damage from the joint.
Therefore, there is a demand for a composite member having a higher joint strength at the joint and a cutting tool made of the same so that the cutting edge is not broken even under heavy cutting conditions where a high load acts on the cutting edge.

In order to solve the problems of the conventional composite member and the cutting tool made of the conventional composite member, the present inventors have made a composite member made of a WC-based cemented carbide and a WC-based cemented carbide and a cutting tool made of the composite material, for example. At the time of ultra-high pressure high temperature sintering, the cutting edge portion made of a composite sintered body to which the WC-based cemented carbide (lining material) is bonded at the same time as the cBN sintered body is sintered and the WC-based cemented carbide tool base (base metal) As a result of diligent research on measures to improve the joining strength of cutting tools joined via joining members.
One WC-based cemented carbide member and the other WC-based cemented carbide member are joined via a joining member mainly composed of Ti, and one WC-based cemented carbide member and the other WC-based cemented carbide member are joined. In the composite member joined by the joint portion, a predetermined layer thickness of the WC-based cemented carbide member near the interface between the joint portion and the WC-based cemented carbide member (hereinafter referred to as WC-based cemented carbide member interface). When the modified layer of WC is formed and the composition of the components contained in the bonded phase of the modified layer is maintained within an appropriate range, the adhesion strength and bonding strength between the WC-based cemented carbide member and the joint portion are improved. As a result, it was found that a composite member having excellent joint strength can be obtained.

When the composite member is used as a material for a cutting tool, breakage occurs from the joint even when it is subjected to heavy cutting of steel or cast iron in which a high load acts on the cutting edge. It was found that excellent cutting performance can be exhibited over a long period of use without doing so.

The present invention has been made based on the above findings.
"(1) A composite member in which WC-based cemented carbide members are joined to each other via a joint portion.
(A) The WC-based cemented carbide member is composed of at least a bonding phase mainly composed of a Co component that fills the gap between the WC particles and the WC particles.
(B) The joint portion has a component composition containing 50 atomic% or more of Ti, and the balance has a component composition containing at least W, C, and Co.
(C) In the WC-based cemented carbide member, the bonded phase composition is W: 5 to 20 atomic%, C: 5 to 20 atomic%, and the balance in the vicinity of the interface between the joint portion and the WC-based cemented carbide member. A modified layer consisting of 60 to 90 atomic% of Co and unavoidable impurities and having an average width of 0.2 to 5.0 μm exists, and the cemented carbide member has a bonded phase composition on the inner side of the cemented carbide member from the modified layer. W: less than 5 atomic%, C: less than 5 atomic%, balance Co and unavoidable impurities.
(2) The composite member according to (1), wherein the joint portion has a thickness of 2 to 100 μm.
(3) A cutting tool characterized by being composed of the composite member according to the above (1) or (2). "
It is characterized by.

The present invention will be described in detail below.

As shown in FIG. 1, a joining member (pure Ti foil containing 85 atomic% or more of Ti, Ti alloy foil, etc.) is arranged between one WC-based cemented carbide member and the other WC-based cemented carbide member. (See FIG. 1 (a)), one WC-based cemented carbide member and the other WC-based cemented carbide member are butted against each other via a joining member, and a predetermined pressing force is applied to a predetermined temperature. The present invention in which the WC-based cemented carbide members are joined via the joint by solid-phase diffusion-bonding the WC-based cemented carbide member and the joining member over time (see FIG. 1 (b)). Can be produced (see FIG. 1 (c)).

FIG. 2 shows an enlarged schematic view of FIG. 1 (c). In FIG. 2, W and W constituting WC particles are contained in the bonding phase near the interface of one WC-based cemented carbide member adjacent to the joint. A modified layer diffused in Co in which C is a bonding phase is formed. Similarly, a modified layer in which W and C are diffused is also formed in the bonded phase near the interface of the other WC-based cemented carbide member adjacent to the joint portion.
Further, the bonding member interposed between the one WC-based cemented carbide member and the other WC-based cemented carbide member is formed by solid-phase diffusion bonding from the WC-based cemented carbide member to its components W, C. , Co is diffused, so that the Ti content is 50 atomic% or more, and the balance is formed as a junction containing at least W, C, and Co.
The composition of the WC-based cemented carbide suitable for forming the modified layer and the joint portion is a WC-based cemented carbide composed of Co: 5 to 15% by mass and the balance WC, but if necessary. , TaC, NbC, one or two or more components selected from among the VC and _Cr 3 _{C 2,} may contain 3 wt% or less in total content.

The solid-phase diffusion bonding adopted in the present invention is the following bonding means.
That is, by abutting the WC-based cemented carbide member and the WC-based cemented carbide member via the joining member and holding the WC-based cemented carbide member at a predetermined temperature and time in a state where a predetermined pressing force is applied, the joining member and the WC-based cemented carbide member are superposed. The cemented carbide component is reacted to form an alloy. At this time, by appropriately controlling the composition and layer thickness of each layer constituting the bonding layer, the bonding having excellent strength can be obtained.
When solid-phase diffusion bonding between WC-based cemented carbide members using a bonding member, the melting point of the bonding member itself must be relatively high (1200 ° C. or higher), and the WC-based cemented carbide member must be at 1000 ° C. or lower. By reacting, the reaction can be controlled so that the brittle phase generated by the reaction does not reduce the strength of the bonding interface, and the diffusion rate becomes imbalanced in the mutual diffusion between the WC-based cemented carbide and the bonding member. Conditions such as the fact that the generated Kirkendal voids are unlikely to occur are required.
In the present invention, a pure Ti foil or a Ti alloy foil having a Ti content of 85 atomic% or more is used as a joining member that meets such requirements.

In the present invention, in the production of the composite member, the WC-based cemented carbide member and the joining member are solid-phase diffusion-bonded. Therefore, the finally formed joint portion of the composite member has a component composition different from that of the joining member. In addition, even in the WC-based cemented carbide member adjacent to the junction, W and C constituting the WC particles diffuse into Co, which is the bonding phase, so that the WC-based cemented carbide before bonding is formed. A modified layer having a composition different from that of the bonded phase of the cemented carbide is formed.
Then, by forming a joint portion having a component composition different from that of the bonding member and forming a modified layer having a composition different from that of the bonding phase of the WC-based cemented carbide before bonding, it can be a starting point of peeling and a propagation path of cracks. The modified layer is strengthened, and as a result, a composite member having excellent strength that is unlikely to peel off from the vicinity of the joint can be produced.

Prior to solid-phase diffusion bonding of the WC-based cemented carbide member and the bonding member, the surface of the WC-based cemented carbide member arranged to face the bonding member is blasted in advance to introduce strain. It is desirable to keep it. By introducing the strain in advance, the strain of WC and Co is relaxed at the time of solid-phase diffusion bonding, and as a result, the reaction between WC and Co and Ti is promoted, even when the solid-phase diffusion bonding temperature is lowered. , A uniform reaction is achieved.

FIG. 3 shows an SEM image of the vicinity of the interface between the WC-based cemented carbide member and the joint in the composite member of the present invention, and FIG. 4 shows a schematic view of the vicinity of the interface.
In the present invention, in the WC-based cemented carbide member adjacent to the joint as shown in FIGS. 3 and 4, W and C, which are components constituting the WC particles, are contained in the bonding phase of the WC-based cemented carbide member. Form a diffused reformed layer.
In the present invention, the modified layer is a region in which the W and C contents diffused from the WC particles are 5 atomic% or more and 20 atomic% or less, respectively, in the bonded phase near the interface of the WC-based superhard alloy member. However, if the average width of the modified layer is less than 0.2 μm, the diffusion of W and C into the bonded phase near the interface of the WC-based superhard alloy member is not sufficient, so that the modifying effect is not exhibited and the modified layer is modified. Layers are more likely to be the starting point for destruction.
On the other hand, when the average width of the modified layer exceeds 5.0 μm, brittleness appears in the formed modified layer, and fracture easily propagates inside the WC-based cemented carbide member.
Therefore, in the present invention, the average width of the modified layer is set to 0.2 to 5.0 μm.

The W and C contents in the bonded phase in the modified layer are in the region of 5 atomic% or more and 20 atomic% or less as described above, but this means that the W content in the modified layer is less than 5 atomic% or If the C content is less than 5%, the effect of modifying the bonded phase is insufficient, so that interfacial peeling is likely to occur between the WC-based superhard alloy member and the joint, while in the modified layer. If the W content or C content exceeds 20% by mass, a large amount of fragile free C phase or η phase is precipitated, and destruction inside the modified layer is likely to occur. Therefore, W in the bonded phase of the modified layer And C content is 5 to 20 atomic%.
Since the main component of the bonded phase of the WC-based cemented carbide member is Co, the bonded phase composition of the modified layer is W: 5 to 20 atomic%, C: 5 to 20 atomic%, and the balance is 60. It becomes ~ 90 atomic% of Co and unavoidable impurities.

On the inner side of the cemented carbide member from the modified layer, the bonded phase composition was W: less than 5 atomic%, C: less than 5 atomic%, the balance Co and unavoidable impurities, but this is the average width of the modified layer. If there is a bonded phase containing 5 atomic% or more of W or C inside the cemented carbide that exceeds the upper limit of 5.0 μm, a free C phase or η phase will appear and the strength of the entire cemented carbide member will decrease. The bonded phase composition on the inner side of the cemented carbide member from the modified layer was W: less than 5 atomic%, C: less than 5 atomic%, the balance Co, and unavoidable impurities.

The average width of the modified layer in the present invention can be obtained, for example, as follows.
As shown in FIGS. 3 and 4, first, a scanning electron microscope and an Auger electron spectroscope are used to observe the vicinity of the interface between the WC-based cemented carbide member and the joint, and the WC-based cemented carbide member is observed. When viewed from the side, the critical position where the WC crystal grains are observed is defined as the interface between the WC-based cemented carbide member and the joint, the interface is the starting point, and the interface is perpendicular to the interface in the inner direction of the WC-based cemented carbide member. In addition, a line measurement with a length of 20 μm is performed. In this line measurement, a total of 10 lines are measured with the interval between each line being 1 μm. From the results of line measurement, the amount of W, C, and Co contained in the bonded phase was obtained, and among the points where W and C were contained in the bonded phase in an amount of 5 atomic% or more, the WC-based cemented carbide member was formed from the interface. The distance to the innermost point is defined as the modified region in each line, and the average width of the modified layer is obtained by averaging the widths of the three modified regions with the widest modified region out of the 10 line measurements. be able to.

Further, the contents of W, C and Co in the modified layer of the present invention can also be determined, for example, as follows.
First, using a scanning electron microscope, the vertical cross section of the vicinity of the boundary between the WC-based cemented carbide member and the joint is observed, and three straight lines parallel to the interface are obtained in the width direction of the modified layer obtained above. Is divided into four equal parts. The coupling phases existing on the three straight lines are selected at three points on each straight line, for a total of nine points, and point measurements are performed at the nine points using an Auger electron spectrometer, and the measured values at the nine points are averaged. Thereby, the contents of W, C and Co can be determined.

In the composite member of the present invention, a joint member made of a pure Ti foil or a Ti alloy foil of 85 atomic% or more is used, and a joint portion is formed by solid-phase diffusion bonding. The composition of the joint portion is 50 atoms of Ti. % Or more, and the balance has a composition containing at least W, C, and Co.
Since W, C, and Co, which are components of the WC-based cemented carbide member, are diffused into the joint portion, the composition of the joint portion changes from the composition of the joint member, but the Ti content of the joint portion is 50. If it is less than atomic%, the joint itself tends to be embrittled, so that the Ti content of the joint needs to be 50 atomic% or more.
As a means for maintaining the Ti content of the joint portion at 50 atomic% or more, for example, a joint member having a thickness of 1 to 100 μm is used, and a pressing force of 0.5 to 5 MPa is applied to 600 to 900. The Ti content of the joint can be 50 atomic% or more by performing solid-phase diffusion bonding under the condition that the temperature is maintained in the temperature range of ° C. for 5 to 600 minutes.
In the composite member of the present invention, when the thickness of the joint portion is 2 μm or less, it is difficult to obtain sufficient joint strength because voids are likely to be generated in the joint portion. It is desirable that the thickness of the joint is in the range of 2 to 100 μm because peeling occurs in the joint and it is difficult to obtain sufficient joint strength.

The composite member of the present invention can be produced, for example, by the method shown below.
First, a pretreatment for introducing strain is performed by blasting the surfaces of one WC-based cemented carbide member and the other WC-based cemented carbide member facing the joint member.
Next, a pure Ti foil as a joining member or a Ti alloy foil containing 85 atomic% or more of Ti is sandwiched between one WC-based cemented carbide member and the other WC-based cemented carbide member. One WC-based cemented carbide member and the other by holding in a vacuum at a predetermined temperature of 600 to 900 ° C. for 5 to 600 minutes, pressurizing under a pressure load of 0.5 to 5 MPa, and solid-phase diffusion bonding. It is possible to manufacture a composite member in which the WC-based cemented carbide member of No. 1 is joined via a joint portion.
As described above, the pretreatment performed before the solid-phase diffusion bonding relaxes the strain of WC and Co during the solid-phase diffusion bonding, and at the same time promotes the diffusion of W and C into Co. This treatment aims to realize a uniform reaction even under relatively low temperature conditions of ~ 900 ° C.

In the composite member of the present invention, a cutting tool can be constructed by using one WC-based cemented carbide member as the cutting edge side and the other WC-based cemented carbide member as a tool base.
More specifically, for example, one WC-based cemented carbide member of the composite member is used as a backing material for the cBN sintered body on the cutting edge side, and the other WC-based cemented carbide member is used as a tool base. By using (base metal), a cBN cutting tool can be formed.

In the present invention, WC-based cemented carbide members (one WC-based cemented carbide member and the other WC-based cemented carbide member) are joined to each other as a pure Ti foil or a Ti alloy containing 85 atomic% or more of Ti. A composite member bonded via a joint formed by solid-phase diffusion bonding using a foil, in which W and C are diffused in the bonding phase near the interface of the WC-based cemented carbide member adjacent to the bonding. By forming a quality layer, keeping the average width of the modified layer within a predetermined range, and controlling the composition of the components contained in the modified layer within an appropriate range, the WC-based cemented carbide member and the joint portion Adhesion strength and joint strength with and from are improved, and as a result, a composite member having excellent joint strength can be obtained.
The cutting tool composed of the composite member does not break from the joint even when it is subjected to heavy cutting in which a high load acts on the cutting edge, and it can be used for a long period of time. , Demonstrates excellent cutting performance.

It is a schematic diagram which showed the manufacturing process of the composite member of this invention, (a) shows the composite member before joining, (b) shows the composite member at the time of solid-phase diffusion joining, and (c) shows the composite member after joining. The enlarged schematic view of FIG. 1C is shown. A cross-sectional SEM image of the vicinity of the interface between the WC-based cemented carbide member and the joint portion of the composite member of the present invention is shown. A schematic diagram of the vicinity of the interface between the WC-based cemented carbide member and the joint portion of the composite member of the present invention is shown.

Next, the present invention will be specifically described based on examples. It should be noted that the examples described below are embodiments of the present invention, and specific embodiments of the present invention are not limited thereto.

As raw material powders, WC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder and Co powder having an average particle size of 0.5 to 1 μm are prepared, and these raw material powders are shown in Table 1. Wet-mixed in a ball mill for 24 hours, dried, and then press-molded into a green compact at a pressure of 100 MPa, and the green compact was pressed in a vacuum of 6 Pa at a temperature of 1400 ° C. and a holding time of 1 hour. Sintering was performed under the conditions to form four types of WC-based superhard alloy sintered bodies (hereinafter, simply referred to as "superhard alloys") A-1 to A-4 shown in Table 1.

Next, as the raw material powder of the cBN sintered body, cBN powder, TiN powder, TiCN powder, TiB ₂ powder, TiC powder, AlN powder, Al ₂ O, each having an average particle size in the range of 0.5 to 4 μm. ₃ powders are prepared, these raw material powders are blended in a predetermined compounding composition, wet-mixed with acetone for 24 hours in a ball mill, dried, and then pressure having a size of 15 mm in diameter × 1 mm in thickness at a pressure of 100 MPa. It was press-molded into powder.
Next, the cemented carbides A-1 to A-4 were used as a sintered body having a size of 15 mm in diameter and 2 mm in thickness, and this was used as a backing material for sintering the cBN sintered body, and the above-mentioned was put on the backing material. The cBN green compacts were laminated in the combination shown in Table 2, and then the laminate was sintered using an ultra-high pressure generator under the conditions of temperature: 1300 ° C., pressure: 5.5 GPa, and time: 30 minutes. Composite sintered bodies B-1 to B-4 were prepared.
Regarding the composition of the cBN sintered body of the composite sintered bodies B-1 to B-4, the area% of cBN was determined as the volume% by image analysis of the SEM observation result of the cross-section polished surface of the cBN sintered body.
For components other than cBN, only the components constituting the main binding phase and other binding phases were confirmed. The results are shown in Table 2.

Next, the pure Ti foil or Ti alloy foil shown in Table 3 was prepared as a joining member.

Next, the joining member shown in Table 3 is inserted between the cemented carbides A-1 to A-4 and the composite sintered bodies B-1 to B-4, and the conditions shown in Table 4 (that is, 1 to 1) are inserted. A pure Ti foil with a thickness of 100 μm or a Ti alloy foil containing 85 atomic% or more of Ti is used as a joining member, and the temperature is 5 to a predetermined temperature within the range of 600 to 900 ° C. in a vacuum of 1 × 10 ^-3 Pa or less. The composite sintered body and the cemented carbide were pressure-bonded under the condition of holding for 600 minutes and applying a pressing force of 0.5 to 5 MPa to prepare the composite members 1 to 10 of the present invention shown in Table 6. In the composite sintered body, the cBN sintered body is the outer surface and the backing material is the inner surface, that is, the WC-based cemented carbide that is the backing material and the WC-based cemented carbide that is the tool base (base metal) form the joining member. It was arranged so as to be joined through.

For comparison, the joining members shown in Table 3 were used, and this was intervened and charged between the cemented carbides A-1 to A-4 and the composite sintered bodies B-1 to B-4, and Table 5 Under the conditions shown in (1), the composite sintered body and the cemented carbide were pressure-bonded to prepare Comparative Example composite members 1 to 10 shown in Table 8. The joint arrangement of the composite sintered body was the same as that of the composite member of the present invention.

High temperature shear strength measurement test:
The composite members 1 to 10 of the present invention and the composite members 1 to 10 of Comparative Examples produced above were subjected to a shear strength measurement test in order to measure the strength of the joint.
The test piece used for the test was made from the composite members 1 to 10 of the present invention and the composite members 1 to 10 of Comparative Example produced above, and the composite sintered body: 1.5 mm (W) × 1.5 mm (L) × 0. 75 mm (H), WC-based cemented carbide substrate (base metal): A test piece for shear strength measurement cut out to a size of 1.5 mm (W) x 4.5 mm (L) x 1.5 mm (H). And said.
The upper and lower surfaces of the test piece are gripped and fixed with a clamp, and a prismatic pressing piece made of cemented carbide with a side of 1.5 mm is used, the ambient temperature is set to 600 ° C., and a load is applied near the center of the upper surface of the test piece. , The load at which the test piece breaks was measured.
Tables 6 and 8 show the measured shear strength values.

Further, with respect to the composite members 1 to 10 of the present invention and the composite members 1 to 10 of the comparative examples, a modified layer in which W and C, which are components constituting WC particles, are diffused in the bonding phase near the interface of the WC-based cemented carbide member. The average width of the particles was measured and calculated as follows using a scanning electron microscope and an Auger electron spectrometer.
First, the vertical cross section is observed near the boundary between the WC-based cemented carbide member and the joint, and the critical position where the WC crystal grains are observed when viewed from the WC-based cemented carbide member side is the WC-based cemented carbide member and the joint. It was defined as the interface with.
Then, 10 lines were measured at 1 μm intervals from the interface to the inside of the WC-based cemented carbide member in the direction perpendicular to the interface over 20 μm, and the W amount, C amount, and Co amount contained in the bonded phase were measured. I asked.
Next, among the points containing 5 atomic% or more of W and C in the bonded phase, the distance from the interface to the innermost point of the WC-based cemented carbide member is defined as the modified region in each line, and 10 line measurements are performed. Of these, the average width of the three modified regions having a wide modified region was averaged to obtain the average width of the modified layer.
Regarding the W amount, C amount, and Co amount in the modified layer, a longitudinal cross-sectional view was observed near the boundary between the WC-based superhard alloy member and the joint portion using a scanning electron microscope, and 5 parallel to the interface. Draw a straight line of the book so as to divide the width direction of the modified layer obtained above into four equal parts, and use an Auger electron spectrometer to perform point measurement on the bonded phase in the modified layer existing on each straight line. By averaging the values at 9 measurement points, the contents of W, C, and Co were determined.
Since the modified layer was not formed in a part of the comparative example composite tool, as a reference, the part inside the cemented carbide member 1 μm from the interface between the WC-based cemented carbide member and the joint was measured and replaced. The value was taken.
Further, for reference, the content of Ti, W, Co, and C in the central portion of the joint defined by the interface between the WC-based cemented carbide member and the joint is determined by using an Auger electron spectrometer. By measuring, this was determined as the composition of the joint.
Tables 6 and 8 show the measurement results of the modified layer on the tool substrate (base metal) side and the composition, thickness, and shear strength of the joint. Tables 7 and 9 show the measurement results of the modified layer on the composite sintered body side. Since the measurement results of the composite members 1 to 4 of the present invention and the composite members 1 to 4 of the comparative examples on the tool base (base body) side and the composite sintered body side were substantially the same, the tool base side is represented as a representative. It was shown to.

Next, a cutting tool composed of the composite members 1 to 10 of the present invention and the composite members 1 to 10 of the comparative example was produced, and the presence or absence of breakage in the cutting process was investigated.
A cutting tool made of a composite member was produced as follows.
The composite sintered bodies B-1 to B-4 produced above were cut into an isosceles triangle having a plane shape: an opening angle of 80 ° and a side of 4 mm × a thickness of 2 mm. Subsequently, the cemented carbides A-1 to A-4 were made into a sintered body having a plane shape: 12.7 mm inscribed circle, a rhombus having an opening angle of 80 ° and a thickness of 4.76 mm, and this baking was performed. A notch having a size corresponding to the shape of the composite sintered body was formed on one corner of one of the vertically parallel planes of the body by using a grinding machine. The area of the bottom surface of this notch is 2.96 mm ² , and the area of the side surface is 4.89 mm ² . Next, the joining member shown in Table 3 is inserted between the cemented carbides A-1 to A-4 and the composite sintered bodies B-1 to B-4, and the composite sintered body is provided under the conditions shown in Table 4. And WC-based cemented carbide are pressure-bonded, and after the outer circumference of this composite member is ground, the cutting edge is honed to R: 0.07 mm to have an insert shape of ISO standard CNGA120408. Tools 1-10 were made.
The composite sintered body was arranged so that the cBN sintered body had an outer surface and the backing material had an inner surface, that is, the backing material and the tool base (base metal) were joined via a joining member.
Further, it was confirmed that the joints of the cutting tools 1 to 10 of the present invention are substantially the same as those of the composite members 1 to 10 of the present invention shown in Table 6.
Similarly, the joining member shown in Table 3 is inserted between the composite sintered bodies B-1 to B-4 produced above and the cemented carbide A-1 to A-4 produced above, and the table is shown. The cutting tools 1 to 10 of Comparative Example were manufactured by pressure joining under the conditions shown in 5.
Further, it was confirmed that the joints of the cutting tools 1 to 10 of the comparative examples are substantially the same as those of the composite members 1 to 10 of the comparative examples shown in Table 8.

Next, the cutting tools 1 to 10 of the present invention and the cutting tools 1 to 10 of the comparative examples are shown below in a state where all of the various cutting tools are screwed to the tip of the tool steel cutting tool with a fixing jig. A dry high-speed heavy-cutting test was conducted on carburized and hardened steel, and the location of the cutting edge dropout and breakage was observed.
Work material: JIS / SCM415 (hardness: 58HRc) round bar,
Cutting speed: 265 m / min. ,
Notch: 0.5 mm,
Feed: 0.35 mm / rev. ,
Cutting time: 17 minutes,
(Normal cutting speed and feed are 150 m / min and 0.2 mm / rev, respectively),
Table 10 shows the cutting test results.

From the values of shear strength shown in Tables 6 and 8, it can be seen that the composite members 1 to 10 of the present invention have excellent joint strength as compared with the composite members 1 to 10 of Comparative Examples.
Further, from the results shown in Table 10, the cutting tools 1 to 10 of the present invention composed of the composite members 1 to 10 of the present invention do not fall off the cutting edge and exhibit excellent cutting performance over a long period of use. On the other hand, it can be seen that in the comparative example cutting tools 1 to 10 composed of the comparative example composite members 1 to 10, the cutting edge falls off from the joint during cutting, and the tool life is reached at an early stage.

In this embodiment, the insert has been specifically described as an example, but the present invention is not limited to the insert, and all cutting tools such as drills and end mills having a joint portion between the cutting edge portion and the tool body. Needless to say, it can be applied to drilling tools such as bits.

The composite member of the present invention has a high joint strength, and the cutting tool produced from this composite member can be used for high-load cutting such as high-speed heavy cutting of various types of steel and cast iron. Since it exhibits stable cutting performance over a long period of time, it is possible to sufficiently satisfy the high performance of the cutting machine, labor saving and energy saving of the cutting process, and cost reduction.

Claims (3)

A composite member in which WC-based cemented carbide members are joined to each other via a joint.
(A) The WC-based cemented carbide member is composed of at least a bonding phase mainly composed of a Co component that fills the gap between the WC particles and the WC particles.
(B) The joint portion has a component composition containing 50 atomic% or more of Ti, and the balance has a component composition containing at least W, C, and Co.
(C) In the WC-based cemented carbide member, the bonded phase composition is W: 5 to 20 atomic%, C: 5 to 20 atomic%, and the balance in the vicinity of the interface between the joint portion and the WC-based cemented carbide member. A modified layer consisting of 60 to 90 atomic% of Co and unavoidable impurities and having an average width of 0.2 to 5.0 μm exists, and the cemented carbide member has a bonded phase composition on the inner side of the cemented carbide member from the modified layer. W: less than 5 atomic%, C: less than 5 atomic%, balance Co and unavoidable impurities. The composite member according to claim 1, wherein the joint portion has a thickness of 2 to 100 μm. A cutting tool characterized by being composed of the composite member according to claim 1 or 2.