JP2018051619A - Composite member and cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite member excellent in high-temperature joint strength prepared by joining two WC-based hard metals via a joint member, and to provide a cutting tool comprising the composite member.SOLUTION: An objective composite member is produced by preparing a joint part by PTLP joint of a joint member comprising a lamination structure of Al foil-Ti foil-Al foil, and joining two WC-based hard metals through the joint part comprising the adhesion layer-intermediate layer-adhesion layer. The adhesion layer has a layer thickness of 0.2-10 μm, and a component composition of 60-98 atom% of Ti and 2-40 atom% of Al. The intermediate layer included between the adhesion layers has the component composition of more than 98 atom% of Ti and less than 2 atom% of Al. The cutting tool comprising the composite member is also provided.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a composite member and a cutting tool excellent in high-temperature bonding strength of a joint portion, and more particularly, a composite member obtained by joining a WC-based cemented carbide and a WC-based cemented carbide, and a cutting tool comprising the composite member. About.

  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. The joining material and the second joining material are joined via a joining material 2 (for example, Ti, Co, Ni) that does not generate a liquid phase at a temperature lower than 1000 ° C., and the joining is performed at a pressure of 0.1 MPa to 200 MPa. It has been proposed to perform heating by energization while pressurizing at a pressure, and the bonded body obtained by this can be used for the bonding layer even when the temperature of the brazing material becomes higher than the temperature at which the brazing material generates a liquid phase during cutting. Since the bonding strength does not decrease, it is considered 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 is reduced by making the thickness of the bonding layer on the back surface smaller 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, and carbides, carbonitrides, and mutual solid solutions of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W. Hard phase consisting of at least one selected from the group consisting of: 50 to 97% by mass, and the balance of the binder phase consisting mainly 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.

JP 2009-241236 A JP 2012-111187 A JP 2014-131819 A

The composite material proposed in Patent Documents 1 to 3 or a cutting tool made of the same exhibits a certain level of performance under normal conditions of cutting. For example, a high load acts on the cutting edge, and high heat generation occurs. Under the accompanying high feed and high cutting heavy cutting conditions, the high-temperature bonding strength cannot be said to be sufficient, and there has been a problem that breakage occurs from the bonded portion.
Therefore, a composite member having a joint portion having a higher high-temperature joint strength that causes a high load to act on the cutting edge and that does not cause breakage from the joint portion even under heavy cutting conditions with high heat generation, and A cutting tool is desired.

In order to solve the problems of the conventional composite member and the cutting tool comprising the same, the present inventors 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 earnest research on measures to improve the joint strength of the joint in the cutting tool joined via the joining member,
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 In the composite member joined by the joint, an adhesive layer with an optimized component composition and layer thickness is formed at the joint adjacent to the end of the WC-based cemented carbide member, and adjacent to the adhesive layer. And it discovered that the composite member which improved the high temperature joint strength of a WC group cemented carbide alloy member and a junction part by forming the center layer of a predetermined component composition was discovered.

And as a material for a cutting tool, when using the composite member, even when a high load acts on the cutting edge, and when subjected to heavy cutting of steel or cast iron with high heat generation, The present inventors have found that excellent cutting performance can be exhibited over a long period of use without causing breakage from the joint.

The present invention has been made based on the above findings,
“(1) A composite member in which WC-based cemented carbide members are joined together via a joint,
(A) The joint is composed of an adhesion layer adjacent to an end of each WC-based cemented carbide member, and an intermediate layer located between the adhesion layers,
(B) The adhesion layer has a layer composition of 0.2 to 10 μm, and has a composition composed of Ti of 60 to 98 atomic% and Al of 2 to 40 atomic%,
(C) The composite member, wherein the intermediate layer located between the adhesion layers has a component composition in which Ti is more than 98 atomic% and Al is less than 2 atomic%.
(2) It is comprised from the composite member as described in said (1), The cutting tool characterized by the above-mentioned. "
It is characterized by.

  The present invention is described in detail below.

As shown in FIG. 1, in the composite member of the present invention, a joining member is disposed 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 abutted with each other through the member, and a predetermined temperature and time are applied in a state where a predetermined pressure is applied, and a WC-based cemented carbide member is taken. The composite member of the present invention in which the WC-based cemented carbide members are joined to each other through the joint portion by joining the joining member and the PTLP (Partial Transient Liquid Phase) (see FIG. 1B). (See FIG. 1C).
Here, PTLP bonding means that only a part of the bonding member is melted during bonding, and the molten member diffuses into the other part of the bonding member or the base material. As a result, the melted member changes to a high melting point phase, and after joining is completed, a low melting point phase does not exist, and the joining method is characterized by high heat resistance joining that does not melt at the joining temperature.

FIG. 2 shows an enlarged schematic diagram of FIG. 1 (c). In FIG. 2, the joint adjacent to the end of one WC-based cemented carbide member has a layer thickness of 0.2 to 10 μm. In addition, an adhesion layer having a component composition of 60 to 98 atomic% (hereinafter, “atomic%” is simply indicated by “%”) and Al of 2 to 40% is formed. At the same time, the joint adjacent to the end of the other WC-based cemented carbide member has a layer thickness of 0.2 to 10 μm, and consists of 60 to 98% Ti and 2 to 40% Al. An adhesion layer having a component composition is formed.
An intermediate layer is formed between the adhesion layer adjacent to the end of one WC-based cemented carbide member and the adhesion layer adjacent to the end of the other WC-based cemented carbide member.
The intermediate layer has a component composition in which Ti exceeds 98% and Al is less than 2%, and preferably has a layer thickness of 1 to 100 μm.

In the present invention, the adhesion layer and the intermediate layer having the specific component composition can be formed by using a bonding member having a specific structure and material.
For example, as a joining member used in the present invention, a joining member having a three-layer structure of Al foil-Ti foil-Al foil can be used, and the thickness of the Al foil is 0.1 to 5 μm, and Ti foil The thickness is preferably 1 to 100 μm.
And the said joining member can be produced by vapor-depositing and forming Al as a film | membrane by vapor deposition on both surfaces of Ti foil, for example.

In the present invention, the joining member is interposed between one WC-based cemented carbide member and the other WC-based cemented carbide member. For example, in a vacuum of 1 × 10 ⁻¹ Pa or less, 670 to 900 A composite member having a joining portion composed of the adhesion layer and the intermediate layer by holding at a predetermined temperature within a range of 5 ° C. for 5 to 600 minutes, pressurizing under a load of 0.5 to 10 MPa, and performing PTLP joining. Can be produced.
In PTLP bonding, the Al foil melts in the above temperature range, and the concavo-convex portions present in the WC-based cemented carbide member are filled with molten Al, thereby improving the wettability of the WC-based cemented carbide member and the joining member. By firmly adhering, a strong bond is formed.
Furthermore, molten Al diffuses into the Ti foil and solidifies by forming an alloy phase with a melting point higher than the melting point of Al alone (about 660 ° C.), so it can be used in a temperature environment above the melting point of Al alone. The bonded portion does not melt, and a composite material having excellent high-temperature bonding strength is formed.

In the composite member of the present invention shown in FIG. 2, the joint portion adjacent to the end portion of each WC-based cemented carbide member has a composition composed of Ti: 60 to 98%, Al: 2 to 40%, An adhesion layer having a layer thickness of 0.2 to 10 μm is formed.
When the contents of Al and Ti in the adhesion layer are each less than 2% or more than 98%, the diffusion of molten Al into Ti is not sufficient, and therefore an alloy phase of Ti and Al (mainly Ti ₃ Al phase) is not formed, and a layer excellent in high-temperature bonding strength is not formed. On the other hand, when the content of Al and Ti in the adhesion layer exceeds 40% or less than 60%, Since the melting point of the alloy phase to be formed is not a high melting point, the adhesion strength at a high temperature is lowered.
Moreover, when the layer thickness of the adhesion layer is 0.2 μm, since the amount of the alloy phase of high melting point Ti and Al is small, the effect of improving the high-temperature bonding strength is small, whereas when the layer thickness of the adhesion layer exceeds 10 μm In addition, brittleness appears in the adhesion layer, and breakage is likely to occur in the adhesion layer portion of the composite layer.
Therefore, in this invention, about the component composition of the said contact | adherence layer, Ti was defined as 60 to 98%, Al was defined as 2 to 40%, and the layer thickness of the adhesion layer was determined as 0.2 to 10 μm.

As shown in FIG. 3, an intermediate layer is interposed between the adhesion layers.
The intermediate layer has a component composition in which Ti exceeds 98% and Al is less than 2%. However, when Ti in the intermediate layer is 98% or less and Al is 2% or more, Al diffuses into Ti. Since the amount becomes excessive, the high-temperature strength of the adhesion layer is lowered due to the generation of the low melting point alloy phase, and breakage at the location of the adhesion layer is likely to occur.
When the thickness of the intermediate layer is less than 10 μm, the layer thickness of the adhesion layer becomes non-uniform, and it is difficult to exhibit satisfactory bonding strength. On the other hand, when the thickness exceeds 100 μm, the properties of the joint become close to that of metal Ti. Since the strength is lowered, the intermediate layer thickness is preferably 10 to 100 μm.

The component composition and layer thickness of the adhesion layer in the present invention can be determined, for example, as follows.
First, using a scanning electron microscope and an Auger electron spectroscope, the longitudinal section of the boundary between the WC-based cemented carbide member and the joint is observed, and WC crystal grains are observed as viewed from the WC-based cemented carbide member side. The critical position is defined as the interface between the WC-based cemented carbide member and the joint, a line segment is drawn in a range of 50 μm from the interface in a direction perpendicular to the interface, and the line segment is analyzed.
In this line analysis, a layer containing 60 to 98% Ti and 2 to 40% Al is defined as an adhesion layer, and a layer having Ti exceeding 98% and Al less than 2% is specified as an intermediate layer. Further, with respect to the line segment, 5 line segments are drawn at a line interval of 5 μm, the line analysis is performed for each line segment, and the thickness of the layer containing 60 to 98% Ti and 2 to 40% Al is measured. Then, the thickness of the adhesion layer was obtained by averaging these measured values.
In addition, for the thickness of the intermediate layer, from the value of the line analysis performed for the five line segments similar to the above, the layer thickness in which Ti exceeds 98% and Al is less than 2% is measured. It can be obtained by averaging.

The composite member of the present invention can constitute a cutting tool by using one WC-based cemented carbide member as the cutting edge portion side and the other WC-based cemented carbide member as the tool base.
More specifically, for example, one WC-based cemented carbide member of the composite member is used as a backing material for a 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, a WC-based cemented carbide member (one WC-based cemented carbide member and the other WC-based cemented carbide member) is joined to a joining member having a three-layer structure of Al foil-Ti foil-Al foil, A composite member joined through a joint formed by PTLP joining, and an adhesive layer having excellent high-temperature joint strength is formed adjacent to the end of the WC-based cemented carbide member. The high-temperature bonding strength is improved.
And the cutting tool comprised from the said composite member does not produce the fracture | rupture from a junction part even if it is a case where it uses for the heavy cutting which a high load acts on a cutting blade, Over a long-term use It demonstrates 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 PTLP joining, (c) shows the composite member after joining. The enlarged schematic diagram of the junction part vicinity of the composite member of this invention is shown.

  Next, the present invention will be specifically described based on examples. In addition, the Example demonstrated below is one embodiment of this invention, Comprising: Specific embodiment of 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 all 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, Al ₂ O each having an average particle size in the range of 0.5 to 4 μm as the raw material powder of the cBN sintered body ₃ powders were prepared, these raw material powders were blended so as to form the sintered body shown in Table 2, wet-mixed with acetone for 24 hours in a ball mill, dried, and then 15 mm in diameter and 1 mm in thickness at a pressure of 100 MPa. Press compacted into compacts with dimensions.
Next, the cemented carbides A-1 to A-4 are made into a sintered body having a diameter of 15 mm and a thickness of 2 mm, and this is used as a backing material during 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, a joining member having a three-layer structure of Al foil-Ti foil-Al foil shown in Table 3 was prepared.

Next, the cemented members A-1 to A-4 and the composite sintered bodies B-1 to B-4 are inserted between the joining members shown in Table 3, and the conditions shown in Table 4 (that is, 1 × The composite sintered body and the cemented carbide alloy under the condition of holding a predetermined temperature in the range of 670 to 900 ° C. for 5 to 600 minutes in a vacuum of 10 ⁻³ Pa or less and applying a pressure load of 0.5 to 10 MPa. The composite members 1 to 10 of the present invention having joint portions composed of an adhesion layer and an intermediate layer shown in Table 4 were produced. The composite sintered body is arranged so 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). It arrange | positioned so that it may join via a joining member.

  For comparison, a joining member 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 1 to produce Comparative Example composite members 1 to 11 having the joints shown in Table 5. The joint arrangement of the composite sintered body was the same as that of the composite member of the present invention.

Moreover, about this invention composite members 1-10 and comparative example composite members 1-11, the component composition of the contact | adherence layer adjacent to the edge part of a WC group cemented carbide alloy member and a composite sintered compact member, the layer thickness of an adhesive layer, Using a scanning electron microscope and an Auger electron spectrometer, measurement and calculation were performed as follows.
First, observe the longitudinal section of the vicinity of the boundary between the WC-based cemented carbide member and the joint and the vicinity of the boundary between the composite sintered body member and the joint, as viewed from the WC-based cemented carbide member side or the composite sintered body member side, The critical position where the WC crystal grains were observed was defined as the interface between the WC-based cemented carbide member and the joint or the interface between the composite sintered body member and the joint.
Next, five lines were measured at intervals of 5 μm over 50 μm in the direction perpendicular to the interface from the interface, and the Ti content and Al content in the joint (adhesion layer and intermediate layer) were measured.
Next, a region containing 60 to 98% Ti and 2 to 40% Al is defined as the adhesion layer, the layer thickness is measured, and the average value of the measured values in the five line measurements is used as the layer thickness of the adhesion layer. Asked. Similarly, the region where Ti is over 98% and Al is less than 2% was measured by the above five line measurements, and averaged to determine the layer thickness of the intermediate layer.
Tables 4 and 5 show the results.

High temperature shear strength measurement test:
The present invention composite members 1 to 10 and comparative example composite members 1 to 11 produced above were subjected to a shear strength measurement test 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. 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 4 and 5 show the measured shear strength values.

Next, the cutting tool which consists of this invention composite member 1-10 and comparative example composite member 1-11 was produced, and the presence or absence of the fracture | rupture generation | occurrence | production in cutting 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 plane shape: an isosceles triangle with an opening angle of 80 ° having 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: an inscribed circle of 12.7 mm and an open angle of 80 ° × 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 . Subsequently, 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 1-10 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.
Moreover, it confirmed that the junction part of these cutting tool 1-10 of this invention was substantially the same as this invention composite member 1-10 shown in Table 4.
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, Pressure bonding was performed under the conditions shown in FIG.
Moreover, it confirmed that the junction part of these comparative example cutting tools 1-11 was substantially the same as the comparative example composite members 1-11 shown in Table 5.

Next, the cutting tools 1 to 10 and the comparative cutting tools 1 to 11 according to the present invention are shown below in a state where all of the various cutting tools are screwed to the tip of the tool steel tool with a fixing jig. A dry high-speed heavy 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: 275 m / min. ,
Cutting depth: 0.5 mm,
Feed: 0.35 mm / rev. ,
Cutting time: 13 minutes
(Normal cutting speed and feed are 150 m / min and 0.2 mm / rev., Respectively)
Table 6 shows the cutting test results.

From the values of the shear strength shown in Tables 4 and 5, it can be seen that the composite members 1 to 10 of the present invention have superior high-temperature bonding strength as compared with the composite members 1 to 11 of the comparative example.
Further, from the results shown in Table 6, the cutting tools 1 to 10 of the present invention constituted by the composite members 1 to 10 of the present invention exhibit excellent cutting performance over a long period of use without dropping of the cutting edge. On the other hand, it can be seen that, in the comparative cutting tools 1 to 11 constituted by the comparative composite members 1 to 10, the cutting edge is dropped 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 high joint strength at high temperatures, and cutting tools made from this composite member should be used for high-load cutting such as high-speed heavy cutting of various steels and cast iron. In addition, since it exhibits stable cutting performance over a long period of time, it can sufficiently satisfy the high performance of cutting equipment, labor saving and energy saving of cutting, and further cost reduction. It is.

Claims (2)

A WC-based cemented carbide member is a composite member joined through a joint,
(A) The joint is composed of an adhesion layer adjacent to an end of each WC-based cemented carbide member, and an intermediate layer located between the adhesion layers,
(B) The adhesion layer has a layer composition of 0.2 to 10 μm, and has a composition composed of Ti of 60 to 98 atomic% and Al of 2 to 40 atomic%,
(C) The composite member, wherein the intermediate layer located between the adhesion layers has a component composition in which Ti is more than 98 atomic% and Al is less than 2 atomic%. A cutting tool comprising the composite member according to claim 1.