WO2017038855A1

WO2017038855A1 - Composite member and cutting tool

Info

Publication number: WO2017038855A1
Application number: PCT/JP2016/075425
Authority: WO
Inventors: 五十嵐　誠; 藤原　和崇
Original assignee: 三菱マテリアル株式会社
Priority date: 2015-08-31
Filing date: 2016-08-31
Publication date: 2017-03-09

Abstract

A composite member (6) for joining WC-based cemented carbide members (1, 2) interposed by a joining layer (7) formed by solid-phase diffusion-joining of a joining member (3) that comprises Ti foil, and a tool comprising the composite member (6), wherein: the joining layer (7) is configured from first layers (8, 12) that are adjacent to the WC-based cemented carbide members (1, 2) and comprise a TiC phase and a metallic W phase such that the TiC phase occupies an average area of 40-60%, second layers (9, 11) that are adjacent to the first layers (8, 12) and comprise a TiCo phase and a metallic Ti phase such that the TiCo phase occupies an average area of 50-95%, and a residual Ti layer (10); and the area of the metallic W phase in the first layer (8, 12) preferably decreases gradually from the cemented carbide member side to the second layer side.

Description

Composite member and cutting tool

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 comprising the composite member. .
This application claims priority based on Japanese Patent Application No. 2015-170656 filed in Japan on August 31, 2015 and Japanese Patent Application No. 2016-165182 filed in Japan on August 25, 2016. Is hereby incorporated by reference.

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

For example, Patent Document 1 discloses a bonded body in which a cermet sintered body is a first material to be bonded 1 and a cBN sintered body or a diamond sintered body is a second material to be bonded 3. Bonding is performed between the material to be bonded and the second material to be bonded through the bonding material 2 that does not generate a liquid phase at a temperature lower than 1000 ° C., and the bonding is performed by heating while applying pressure at a pressure of 0.1 MPa to 200 MPa. It has been proposed that the joined body obtained by this does not lower the joining strength of the joining layer even if the brazing material becomes a temperature higher than the temperature at which the brazing material generates a liquid phase during cutting. It is said to be suitable as a high-speed cutting tool or a CVD-coated cutting tool.

Patent Document 2 discloses a bonded body in which a cemented carbide sintered body is a first material to be bonded 1 and a cBN sintered body is a second material to be bonded 2. The two materials to be joined are joined to each other by at least two surfaces consisting of a back surface and a bottom surface of the second material to be joined, with a joining material 3 containing titanium (Ti), 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 bonding strength on the back surface is made thinner than the thickness of the bonding layer on the bottom surface. It has been proposed to obtain a joined body such as a high cutting tool.

Further, Patent Document 3 discloses a cBN sintered body containing 20 to 100% by mass of cBN, carbides of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W, carbonitrides, and their mutual solid solutions. Hard phase composed of at least one selected from the group consisting of: 50 to 97% by mass, and the balance as a main component of at least one selected from the group consisting of Co, Ni and Fe: 3 to In a composite of 50% by mass of a hard alloy, a bonding layer is provided between the cBN sintered body and the hard alloy, and the bonding layer is composed of a ceramic phase and a metal phase. 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 (A) Japanese Unexamined Patent Publication No. 2012-111187 (A) Japanese Unexamined Patent Publication No. 2014-131819 (A)

The composite material proposed in Patent Documents 1 to 3 or a cutting tool made of the composite material exhibits a certain level of performance under normal conditions of cutting. For example, a high feed and a high incision in which a high load acts on the cutting edge. Under heavy cutting conditions, it could not be said that the joining strength was still sufficient, and there was a risk of breakage from the joint.
Therefore, there is a demand for a composite member having a higher joint strength and a cutting tool made of the same that does not cause breakage from the joint even under heavy cutting conditions in which a high load acts on the cutting edge.

In order to solve the problems of the conventional composite member and the cutting tool comprising the same, the inventors of the present application have prepared a composite member comprising a WC-base cemented carbide and a WC-base cemented carbide and a cutting tool comprising the composite material, for example, A cutting edge portion made of a composite sintered body obtained by bonding a WC-based cemented carbide (backing material) and a WC-based cemented carbide tool base (base metal) simultaneously with sintering of a cBN sintered body during ultra-high pressure and high-temperature sintering. As a result of diligent research on measures to improve the joint strength of the joint in a cutting tool joined via a joining member, the inventors have found that the following explanation is made.
One WC-based cemented carbide member (hereinafter referred to as “WC-based cemented carbide member A”) and the other WC-based cemented carbide member (hereinafter referred to as “WC-based cemented carbide member B”) are made of Ti foil. As a bonding layer adjacent to the WC-based cemented carbide member A in a composite member in which the WC-based cemented carbide member A and the WC-based cemented carbide member B are bonded by a bonding layer, TiC is used as a bonding layer. A first A layer composed of a phase and a metal W phase is formed; a second A layer composed of a TiCo phase and a metal Ti phase is formed adjacent to the first A layer; and the WC-based cemented carbide member B Similarly, a 1B layer composed of a TiC phase and a metal W phase is formed as a bonding layer adjacent to the WC-based cemented carbide member B, and also composed of a TiCo phase and a metal Ti phase adjacent to the 1B layer. A second B layer is formed and further sandwiched between the second A layer and the second B layer. In the central region of the bonding layer, a residual Ti layer is formed, and the WC-based cemented carbide member A—the first A layer—the second A layer—the remaining Ti layer—the second B layer—the first B layer—the WC-based cemented carbide member. In the composite member joined in the order of B, the area ratio and the layer thickness of the TiC phase in the first A layer and the first B layer, and the area ratio and the layer thickness of the TiCo phase in the second A layer and the second B layer are within an appropriate range. When maintained, the adhesion strength and bonding strength between the WC-based cemented carbide member and the bonding layer can be improved.

Further, by sequentially increasing the area ratio of the TiC phase in the first A layer from the WC-based cemented carbide member A side toward the second A layer side, the TiC phase in the first B layer By gradually increasing the area ratio from the WC-based cemented carbide member B side toward the second B-layer side, the adhesion strength and bonding strength between the WC-based cemented carbide member and the joining layer can be further improved. I found out.

And when the composite member is used as a material for a cutting tool, even if it is used for heavy cutting of steel or cast iron in which a high load acts on the cutting edge, breakage from the joint portion will occur. It has been found that excellent cutting performance can be exhibited over a long period of use.

This invention is made | formed based on the said knowledge, Comprising: It has the following aspects.
(1) A composite member in which one WC-based cemented carbide member A and the other WC-based cemented carbide member B are joined via a joining layer,
(A) A first A layer composed of a TiC phase and a metal W phase is formed adjacent to one WC-based cemented carbide member A, and the average area ratio of the TiC phase in the first A layer is 40 to 60%. And the thickness of the first A layer is 0.5 to 3 μm,
(B) A second A layer composed of a TiCo phase and a metallic Ti phase is formed adjacent to the 1A layer, and the average area ratio of the TiCo phase in the second A layer is 50 to 95%. The thickness of the 2A layer is 0.5-3 μm,
(C) A first B layer composed of a TiC phase and a metal W phase is formed adjacent to the other WC-based cemented carbide member B, and the average area ratio of the TiC phase in the first B layer is 40 to 60%. And the thickness of the first B layer is 0.5 to 3 μm,
(D) A second B layer composed of a TiCo phase and a metallic Ti phase is formed adjacent to the 1B layer, and the average area ratio of the TiCo phase in the second B layer is 50 to 95%. The thickness of the 2B layer is 0.5-3 μm,
(E) A residual Ti layer is present in the central region of the bonding layer sandwiched between the second A layer and the second B layer, and one WC-based cemented carbide member A—first A layer—second A layer—residual Ti A composite member characterized in that the layer, the second B layer, the first B layer, and the other WC-based cemented carbide member B are joined in this order.
(2) The area ratio of the metal W phase in the first A layer gradually decreases from one WC-based cemented carbide member A side toward the second A layer side, or occupies the first B layer. The composite member according to (1) above, wherein the area ratio of the metal W phase decreases sequentially from the other WC-based cemented carbide member B side toward the second B layer side.
(3) The area ratio of the metal W phase in the first A layer gradually decreases from one WC-based cemented carbide member A side toward the second A layer side, and occupies the first B layer. The composite member according to (1) above, wherein the area ratio of the metal W phase decreases sequentially from the other WC-based cemented carbide member B side toward the second B layer side.
(4) A cutting tool comprising the composite member according to any one of (1) to (3).

Hereinafter, the present invention will be described in detail.

As shown in FIG. 1, a joining member (3) is disposed between one WC-based cemented carbide member A (1) and the other WC-based cemented carbide member B (2) (FIG. 1 (a)). Reference), one WC-based cemented carbide member A (1) and the other WC-based cemented carbide member B (2) are abutted with each other via the joining member (3), and a predetermined pressure is applied. The WC-based cemented carbide member (1) is joined to the joining member (3) by solid phase diffusion bonding over a predetermined temperature and time (see FIG. 1B). (1, 2) A composite member (6) according to one embodiment of the present invention in which the members are bonded to each other via a bonding layer (7) (hereinafter referred to as "the composite member of the present invention") can be produced (Fig. 1 (c)).

FIG. 2 shows an enlarged schematic view of FIG. 1 (c). In FIG. 2, a first A layer (8) is formed adjacent to one WC-based cemented carbide member A (1). A second A layer (9) is formed adjacent to the layer (8).
Further, a first B layer (12) is formed adjacent to the other WC-based cemented carbide member B (2), and a second B layer (11) is formed adjacent to the first B layer (12).
Furthermore, a residual Ti layer (10) exists in the central region of the bonding layer (7) sandwiched between the second A layer (9) and the second B layer (11).
One WC-based cemented carbide member A (1) —the first A layer (8) —the second A layer (9) —the remaining Ti layer (10) —the second B layer (11) —the first B layer (12) — The composite member (6) joined in the order of the other WC-based cemented carbide member B (2) is formed.
The joining layer (7) referred to in this specification is the first A formed between the one WC-based cemented carbide member A (1) and the other WC-based cemented carbide member B (2). The whole layer consisting of the layer (8), the second A layer (9), the remaining Ti layer (10), the second B layer (11) and the first B layer (12) is said.

The solid phase diffusion bonding in the above-mentioned specification of the present application is the following bonding means.
That is, the WC-based cemented carbide member (1) and the WC-based cemented carbide member (2) are brought into contact with each other via the joining member (3), and are maintained at a predetermined temperature and time with a predetermined pressure applied. By this, a joining member and a WC group cemented carbide component are made to react and an alloy is formed. Under the present circumstances, it can be set as the joining which was excellent in the intensity | strength by controlling appropriately the composition and layer thickness of each layer which comprise a joining layer (7).
In the solid phase diffusion bonding of the WC-based cemented carbide members (1, 2) using the bonding member (3), the melting point of the bonding member (3) itself is relatively high (1200 ° C or higher). Reacting with the WC-based cemented carbide at 1000 ° C. or less, being able to control the reaction so that the brittle phase produced by the reaction does not reduce the strength of the joint interface, and the WC-based cemented carbide (1, 2) In the mutual diffusion of the joining member (3), conditions such as the difficulty of generating Kirkendall voids caused by an unbalanced diffusion rate are required.
In this invention, Ti foil was used as a joining member (3) meeting such a requirement.

In the production of the composite member (6) of the present invention, since the WC-based cemented carbide members (1, 2) and the joining member (3) are solid phase diffusion joined, the finally formed composite member (6) In the bonding layer (7), layers having different component compositions, that is, the first A layer (from the one WC-based cemented carbide member A (1) to the other WC-based cemented carbide member B (2) ( 8) The second A layer (9), the remaining Ti layer (10), the second B layer (11), and the first B layer (12) are formed.
The first A layer (8) formed adjacent to one WC-based cemented carbide member A (1) and the second layer formed adjacent to the other WC-based cemented carbide member B (2). The 1B layer (12) (hereinafter, the first A layer and the first B layer may be collectively referred to as “first layer”) is a first layer composed of a TiC phase and a metal W phase. The average area ratio of the TiC phase in the layer is 40 to 60%, and the thickness of the first layer is 0.5 to 3 μm.
Further, a second A layer (9) is adjacent to the first A layer (8), and further a second B layer (11) (hereinafter referred to as a second A layer and a second B layer is adjacent to the first B layer (12). Are generally referred to as “second layer.”), But the second layer is composed of a TiCo phase and a metallic Ti phase, and the average area ratio of the TiCo phase in the second layer is 50. The thickness of the second layer is 0.5 to 3 μm.

Here, the metal W phase in the first layer has a thermal expansion coefficient smaller than that of the WC-based cemented carbide, and the TiC phase has a thermal expansion coefficient larger than that of the WC-based cemented carbide but smaller than that of the metal Ti. Therefore, the apparent thermal expansion coefficient of the first layer is an intermediate value between the WC-based cemented carbide and the metal Ti.
Therefore, by forming the first layer composed of the TiC phase and the metal W phase in contact with the WC-based cemented carbide, the WC-based cemented carbide (1, 2) and the bonding layer (7) are caused by the difference in thermal expansion coefficient. The thermal stress at the time of bonding generated between the two is relaxed, and the formation of residual stress is also suppressed.

In order to have such a thermal expansion coefficient in the first layer, it is necessary to set the average area ratio of the TiC phase in the first layer to 40 to 60%.
This is because when the average area ratio of the TiC phase is less than 40% or exceeds 60%, the first layer cannot sufficiently perform the stress relaxation function.
Further, if the thickness of the first layer is less than 0.5 μm, sufficient stress relaxation cannot be achieved. On the other hand, if the layer thickness exceeds 3 μm, the brittleness of the first layer becomes obvious, and the composite member (6) When a high load is applied to the bonding layer (7), cracks are likely to be generated and a crack propagation path is formed, and it becomes impossible to maintain a strong bonding state with the WC-based cemented carbide. Is 0.5 to 3 μm.

Further, as described above, the average area ratio of the TiC phase in the first layer is 40 to 60%, but within the range of the average area ratio 40 to 60% of the TiC phase, the WC-based cemented carbide side When the occupation area ratio of the metal W phase is relatively increased and the occupation area ratio of the metal W phase is sequentially decreased toward the second layer (or remaining Ti layer) side, the WC-based cemented carbide Since the thermal expansion coefficient sequentially increases from the side toward the second layer (or the remaining Ti layer), a relatively smooth change in the thermal expansion coefficient is formed in the first layer.
Therefore, in order to obtain a composite member (6) having a more sound joined state without generating a large residual stress at the interface of each layer of the WC-based cemented carbide-first layer-second layer-remaining Ti layer. In the first layer, the occupied area ratio of the metal W phase on the WC-based cemented carbide side is relatively increased, and the occupied area ratio of the metal W phase is sequentially increased toward the second layer (or remaining Ti layer) side. It is desirable to reduce it. The effect of reducing the residual stress is effective even with either the first A layer (8) or the second B layer (11), but both the first A layer (8) and the second B layer (11) are effective. In the first layer, the occupied area ratio of the metal W phase on the WC-based cemented carbide side is relatively increased, and the occupied area ratio of the metal W phase is sequentially increased toward the second layer (or remaining Ti layer) side. Since the effect of reducing the residual stress is further increased by reducing the thickness, it is desirable to form the above structure in both the first A layer (8) and the second B layer (11).

As described above, a layer composed of a TiCo phase and a metallic Ti phase is formed as the second layer in the bonding layer (7), but the formation of the TiCo phase prevents the precipitation of the metallic Co phase having a large thermal expansion coefficient. The stress relaxation is achieved, and the presence of the metallic Ti phase relaxes the difference in thermal expansion coefficient between the first layer and the remaining Ti layer (10) located substantially in the center of the bonding layer (7). Demonstrate.
However, when the average area ratio of the TiCo phase in the second layer is less than 50%, precipitation of metal Co cannot be avoided, and local thermal stress is generated by the metal Co present in the second layer, It tends to be a separation starting point in the second layer. On the other hand, when the average area ratio of the TiCo phase in the second layer exceeds 95%, the thermal stress relaxation effect between the first layer and the remaining Ti phase (10) is not sufficiently exhibited.
Therefore, the average area ratio of the TiCo phase in the second layer is 50 to 95%.
If the thickness of the second layer is less than 0.5 μm, sufficient stress relaxation cannot be achieved. On the other hand, if the thickness of the second layer exceeds 3 μm, the brittleness of the second layer becomes obvious and the composite member (6) When a high load is applied to the bonding layer (7), cracks are likely to be generated and a crack propagation path is formed, and a strong bonding state with the WC-based cemented carbide cannot be maintained. Is 0.5 to 3 μm.

An unreacted residual Ti layer (10) in the solid phase diffusion bonding is formed in the middle of the bonding layer (7), that is, between the second A layer (9) and the second B layer (11). Let
As described above, the first layer and the second layer having the stress relaxation action of the bonding layer (7) are each formed with a thickness of 0.5 to 3 μm, but the solid phase diffusion bonding conditions are within an appropriate range. Exceeding the above, the formation reaction of the TiC phase of the first layer or the TiCo phase of the second layer is excessively promoted, and the residual Ti layer (10) disappears. As a result, the layer becomes brittle and locally The generation of thermal stress causes the strength of the bonding layer (7) to decrease.
In order to avoid such an adverse effect, it is important to leave a Ti layer having an appropriate thickness at substantially the center of the bonding layer (7) sandwiched between the second A layer (9) and the second B layer (11). It is.
Although depending on the solid phase diffusion bonding conditions such as the bonding temperature, bonding time, and applied pressure, a Ti foil having a thickness of 4 to 50 μm can be used as the bonding member (3). In this case, the layer thickness of the remaining Ti layer (10) is desirably 2 to 40 μm.

The composite member (6) of the present invention can be produced, for example, by the following method.
First, a pretreatment for introducing a strain into the joint surface by blasting each joint surface of one WC-base cemented carbide member A (1) and the other WC-base cemented carbide member B (2). Do.
Next, a Ti foil as a joining member (3) is sandwiched between one WC-based cemented carbide member A (1) and the other WC-based cemented carbide member B (2). By holding at a predetermined temperature of 600 to 900 ° C. for 5 to 600 minutes, pressurizing under a pressure of 0.5 to 10 MPa, and performing solid phase diffusion bonding, one WC-based cemented carbide member A (1) and the other The composite member (6) in which the WC-based cemented carbide member B (2) is bonded via the bonding layer (7) can be produced.
Here, by performing a pretreatment for introducing strain on the joint surface of the WC-based cemented carbide member (1, 2), the strain of WC and Co is alleviated at the time of joining, and at the same time, This reaction is promoted and a uniform reaction is realized even under a relatively low temperature condition of 600 to 900 ° C., and a first layer composed of a TiC phase and a metal W phase and a second layer composed of a TiCo phase and a metal Ti phase are provided in a predetermined A remaining Ti layer (10) is formed in the middle of the bonding layer (7) sandwiched between the second A layer (9) and the second B layer (11).

In the composite member (6) of the present invention, for example, one WC-based cemented carbide member A (1) is used as the cutting edge portion side, and the other WC-based cemented carbide member B (2) is used as a tool base. A cutting tool can be constructed.
That is, one WC-based cemented carbide member A (1) of the composite member (6) is used as the backing material of the cBN sintered body on the cutting edge side, and the other WC-based cemented carbide member B (2) is used. By using a tool base (base metal), a cBN cutting tool can be formed.

As a method of measuring the bonding layer (7) of the composite member (6) of the present invention, the bonding layer is observed in a longitudinal section using a scanning electron microscope and an energy dispersive X-ray spectrometer, and a WC-based cemented carbide member ( 1, 2) and the interface between the bonding layers, element mapping is performed within a range of ± 100 μm in a direction perpendicular to the interface. From the mapping result, the location of each of WC, Co, metal W, TiC, metal Ti, and TiCo is specified, the location where WC and Co are present is the cemented carbide member, and the location where metal W and TiC are present One layer is a second layer where metal Ti and TiCo exist, and a remaining Ti layer where metal Ti is mainly present. Ten straight lines perpendicular to the abutting surfaces of the WC-based cemented carbide members (1, 2) are drawn at intervals of 1 μm or more, and the distance of these straight lines crossing each layer is averaged to obtain the thickness of each layer. Further, the first layer and the second layer were separated and extracted from the mapping result by image processing, and the area ratio occupied by the TiC phase in the first layer and the area ratio occupied by the TiCo phase in the second layer were determined.
Moreover, the change of the area ratio of the metal W phase in a 1st layer can be calculated | required by measuring the area ratio to the layer thickness direction of the TiC phase in a 1st layer.

The present invention is a composite member in which one WC-based cemented carbide member A and the other WC-based cemented carbide member B are joined through a joining layer formed by solid phase diffusion joining using a Ti foil as a joining member. The bonding layer includes a first layer composed of a TiC phase and a metal W phase, a second layer composed of a TiCo phase and a metal Ti phase, and a residual Ti layer, and specifies a phase formed in each layer. Since the internal residual stress is made as small as possible by controlling the thermal expansion coefficient over the entire composite member, between one WC-based cemented carbide member A-bonding layer-the other WC-based cemented carbide member B. It has excellent bonding strength. As a result, the strength of the composite member as a whole is improved, and even when a high load is applied to the composite member, no breakage occurs in the bonding layer portion.
Therefore, the cutting tool composed of the composite member does not cause breakage from the joining layer portion even when subjected to heavy cutting where a high load acts on the cutting edge. It exhibits excellent cutting performance.

It is the schematic diagram which showed the preparation process of the composite member of this invention, Comprising: (a) is before joining, (b) is at the time of solid phase diffusion joining, (c) shows the composite member after joining. The enlarged schematic diagram of FIG.1 (c) is shown. Schematic diagram (image used for elemental mapping of longitudinal section) of WC-based cemented carbide member-first layer-second layer-remaining Ti layer of the composite member of the present invention is shown. The black portion and the white portion in the first layer (the first A layer (8)) correspond to TiC and metal W, respectively. In the second layer (second A layer (9)), the light gray part and the dark gray part correspond to TiCo and metal Ti, respectively. In FIG. 3, the W content is large on the upper layer side, and the W content decreases toward the lower layer side.

Next, the present invention will be specifically described based on examples. In addition, the Example demonstrated below is one Embodiment of this invention, Comprising: This invention is not restrict | limited to this.

As raw material powders, WC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder and Co powder each having an average particle diameter of 0.5 to 1 μm were prepared. These raw material powders are shown in Table 1. It is blended into the blended composition, wet mixed in a ball mill for 24 hours, dried, and then pressed into a green compact at a pressure of 100 MPa, and this green compact is vacuumed at 6 Pa, temperature 1400 ° C., holding time 1 hour. Sintering was performed under the conditions to form four types of WC-based cemented carbide sintered bodies (hereinafter simply referred to as “superhard alloys”) A-1 to A-4 shown in Table 1.

Next, cBN powder, TiN powder, TiCN powder, TiB ₂ powder, TiC powder, AlN powder, and Al ₂ O each having an average particle size in the range of 0.5 to 4 μm are used as raw material powders for the cBN sintered body. ₃ powders were prepared, these raw material powders were blended in a prescribed composition, wet mixed with acetone for 24 hours in a ball mill, dried, and then pressure having a size of 15 mm diameter × 1 mm thickness at 100 MPa pressure. Press-molded into powder.
Next, the cemented carbides A-1 to A-4 are formed into a sintered body having a diameter of 15 mm × thickness of 2 mm, and this is used as a backing material during the sintering of the cBN sintered body. cBN compacts were laminated in the combinations shown in Table 2, and this laminate was then sintered using an ultrahigh pressure generator at a temperature of 1300 ° C., a pressure of 5.5 GPa, and a time of 30 minutes. Composite sintered bodies B-1 to B-4 were produced.
Regarding the composition of the cBN sintered bodies 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.
About components other than cBN, it stopped only to confirm the component which comprises the main binder phase and other binder phases. The results are shown in Table 2.

Next, Ti foils shown in Table 3 were prepared as bonding members.

Next, the joining members shown in Table 3 are 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, ie, 1 to 1 Using a 50 μm thick Ti foil as the joining member, hold it at a predetermined temperature in the range of 600 to 900 ° C. for 5 to 600 minutes in a vacuum of 1 × 10 −3 Pa or less, and apply a pressure of 0.5 to 10 MPa. The composite sintered body and the cemented carbide were pressure bonded under the conditions described above to produce the composite members 1 to 9 of the present invention shown in Table 6. Note that the composite sintered body is such that 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) are the bonding members. It arrange | positioned so that it might join.

For comparison, a joining member having the size shown in Table 3 was used, and this was interposed between cemented carbides A-1 to A-4 and composite sintered bodies B-1 to B-4. The composite sintered body and the cemented carbide were pressure-bonded under the conditions shown in Table 5 to produce comparative example composite members 1 to 10 shown in Table 7. 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:
For the composite members 1 to 9 of the present invention and the comparative composite members 1 to 10 produced as described above, a shear strength measurement test was performed in order to measure the strength of the joint.
The test pieces used for the test were composite sintered bodies: 1.5 mm (W) × 1.5 mm (L) × 0.00 mm from the composite members 1 to 9 of the present invention and the composite members 1 to 10 of the comparative example prepared above. 75 mm (H), WC-based cemented carbide substrate (base metal): 1.5 mm (W) x 4.5 mm (L) x 1.5 mm (H) cut out to obtain a shear strength measurement specimen It was.
The upper and lower surfaces of the test piece are clamped and fixed, 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 7 show the measured shear strength values.

In addition, for the composite members 1 to 9 of the present invention and the comparative composite members 1 to 10, the composition analysis of the longitudinal section of the WC-based cemented carbide and the joint was performed using a scanning electron microscope and an energy dispersive X-ray spectrometer. went.
FIG. 3 shows a schematic diagram (image used for elemental mapping of the longitudinal section) of the WC-based cemented carbide member-first layer-second layer-residual Ti layer of the composite member of the present invention. The black portion and the white portion in the first layer (the first A layer (8)) correspond to TiC and metal W, respectively. In the second layer (second A layer (9)), the light gray part and the dark gray part correspond to TiCo and metal Ti, respectively. In FIG. 3, the W content is large on the upper layer side, and the W content decreases toward the lower layer side.
Element mapping is performed within the range of ± 100 μm in the direction perpendicular to the interface centering on the interface between the WC-based cemented carbide member and the bonding layer, and the WC phase, Co phase, TiC phase, metal W phase, TiCo phase, and metal Ti While specifying the phase, the cemented carbide member, the first layer, the second layer, and the remaining Ti layer were specified. Moreover, the area ratio which a TiC phase and a TiCo phase occupy was measured from the result of element mapping.
For the first layer, the first layer is equally divided into three layers in the thickness direction with the carbide member side layer, the center layer, and the second layer side layer, and the area ratio of the metal W phase in each layer is obtained from the element mapping result. It was.
Furthermore, the layer thicknesses of the first layer, the second layer, and the remaining Ti layer were determined.
In addition, the center partial area | region of the joining layer containing Ti content exceeding 90 atomic% was specified as a residual Ti layer.
Tables 6 and 8 show the results of the first A layer, the second A layer, the remaining Ti layer, and the shear strength. Tables 7 and 9 show the measurement results of the first B layer and the second B layer. For the composite members 1 to 4 of the present invention and the comparative composite members 1 to 4 and 10, the first A layer and the first B layer, and the second A layer and the second B layer were substantially equivalent. The description of the second B layer was omitted.

Next, cutting tools composed of the composite members 1 to 9 of the present invention and the comparative composite members 1 to 10 were prepared, 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 a planar shape: an isosceles triangle having an opening angle of 80 ° with a side of 4 mm × thickness: 2 mm. Subsequently, the cemented carbides A-1 to A-4 are formed into a sintered body having a planar shape: 12.7 mm inscribed circle and an open angle of 80 ° rhombus × thickness: 4.76 mm. A notch having a size corresponding to the shape of the composite sintered body was formed in one corner of any one of the upper and lower parallel surfaces of the bonded body 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 members shown in Table 3 are 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 subjected to the conditions shown in Table 4. And the WC base cemented carbide are pressure bonded, and after cutting the outer periphery of this composite member, the cutting edge portion is subjected to a honing process of R: 0.07 mm to have an ISO standard / CNGA120408 insert shape. Tools 1 to 9 were produced.
The composite sintered body was arranged so that the cBN sintered body was the outer surface and the backing material was the inner surface, that is, the backing material and the tool base (base metal) were joined via the joining member.
Further, it was confirmed that the joint portions of the cutting tools 1 to 9 of the present invention were substantially the same as the composite members 1 to 9 of the present invention shown in Table 6.
Similarly, the joining members shown in Table 3 are inserted between the composite sintered bodies B-1 to B-4 produced above and the cemented carbides A-1 to A-4 produced above, and Comparative example cutting tools 1 to 10 were produced by pressure bonding under the conditions shown in FIG.
Further, it was confirmed that the joint portions of these comparative cutting tools 1 to 10 were substantially the same as the comparative composite members 1 to 10 shown in Table 7.

Next, the cutting tools 1 to 9 of the present invention and the comparative cutting tools 1 to 10 in the state in which each of the various cutting tools is screwed to the tip of the tool steel tool with a fixing jig will be described below. A dry high-speed cutting test of carburized and hardened steel was performed, and the tip of the blade was dropped and the location of the fractured portion was observed.
Work material: JIS / SCM415 (hardness: 58HRc) round bar,
Cutting speed: 250 m / min. ,
Cutting depth: 0.4 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 16 minutes,
(Normal cutting speed is 150 m / min),
Table 10 shows the cutting test results.

From the values of the shear strengths shown in Tables 6 and 8, it can be seen that the composite members 1 to 9 of the present invention have superior joint strength as compared with the comparative composite members 1 to 10.
Further, from the results shown in Table 10, the cutting tools 1 to 9 of the present invention composed of the composite members 1 to 9 of the present invention exhibit excellent cutting performance over a long period of use without the removal of the cutting edge. On the other hand, it can be seen that, in the comparative cutting tools 1 to 10 composed of the comparative composite members 1 to 10, the cutting edge falls off from the joint during cutting, and the tool life is reached early.

In the present embodiment, the insert has been specifically described as an example. However, the present invention is not limited to the insert, and all cutting tools having a joint between the cutting edge portion and the tool body, such as a drill and an end mill. Needless to say, the present invention is applicable to drilling tools such as bits.

The composite member of the present invention has a high bonding strength, and the cutting tool produced from this composite member can be used for high-load cutting of various steels and cast irons, and is stable over a long period of time. Since the cutting performance is exhibited, it is possible to satisfactorily cope with high performance of the cutting device, labor saving and energy saving of the cutting work, and further cost reduction.

1 WC-based cemented carbide member A
2 WC-based cemented carbide member B
3 Joining member (Ti foil)
4 Pressurization 5 Solid phase diffusion bonding 6 Composite member 7 Bonding layer 8 1A layer (TiC + metal W)
9 Second A layer (TiCo + metal Ti)
10 Remaining Ti layer 11 Second B layer (TiCo + metal Ti)
12 1B layer (TiC + metal W)

Claims

One WC-based cemented carbide member A and the other WC-based cemented carbide member B are composite members joined via a joining layer,
(A) A first A layer composed of a TiC phase and a metal W phase is formed adjacent to one WC-based cemented carbide member A, and the average area ratio of the TiC phase in the first A layer is 40 to 60%. And the thickness of the first A layer is 0.5 to 3 μm,
(B) A second A layer composed of a TiCo phase and a metallic Ti phase is formed adjacent to the 1A layer, and the average area ratio of the TiCo phase in the second A layer is 50 to 95%. The thickness of the 2A layer is 0.5-3 μm,
(C) A first B layer composed of a TiC phase and a metal W phase is formed adjacent to the other WC-based cemented carbide member B, and the average area ratio of the TiC phase in the first B layer is 40 to 60%. And the thickness of the first B layer is 0.5 to 3 μm,
(D) A second B layer composed of a TiCo phase and a metallic Ti phase is formed adjacent to the 1B layer, and the average area ratio of the TiCo phase in the second B layer is 50 to 95%. The thickness of the 2B layer is 0.5-3 μm,
(E) A residual Ti layer is present in the central region of the bonding layer sandwiched between the second A layer and the second B layer, and one WC-based cemented carbide member A—first A layer—second A layer—residual Ti A composite member characterized in that the layer, the second B layer, the first B layer, and the other WC-based cemented carbide member B are joined in this order.
The area ratio of the metal W phase in the first A layer gradually decreases from one WC-based cemented carbide member A side toward the second A layer side, or the metal W phase in the first B layer. 2. The composite member according to claim 1, wherein the area ratio of the composite member decreases sequentially from the other WC-based cemented carbide member B side toward the second B layer side.
The area ratio of the metal W phase in the first A layer gradually decreases from one WC-based cemented carbide member A side toward the second A layer side, and the metal W phase in the first B layer 2. The composite member according to claim 1, wherein the area ratio of the composite member decreases sequentially from the other WC-based cemented carbide member B side toward the second B layer side.
A cutting tool comprising the composite member according to any one of claims 1 to 3.