Composite part and cutting tool

Abstract

A composite member in which WC-based cemented carbide members are bonded to each other via a bonding layer formed by solid phase diffusion bonding of a bonding member made of a Ti foil. The bonding layer is constituted by first layers adjacent to the WC-based cemented carbide members and made of a TiC phase and a metal W phase in which an average area ratio of the TiC phase is 40 to 60%. The bonding layer also includes second layers adjacent to the first layers and made of a TiCo phase and a metal Ti phase in which an average area ratio of the TiCo phase is 50 to 95%, and a residual Ti layer.

Claims

1. A composite member comprising: a WC-based cemented carbide member A; a WC-based cemented carbide member B; and a bonding layer, the WC-based cemented carbide member A and the WC-based cemented carbide member B being bonded to each other via the bonding layer, wherein (a) a first A layer made of a TiC phase and a metal W phase is formed adjacent to the WC-based cemented carbide member A, an average area ratio of the TiC phase in the first A layer being 40% to 60%, and a thickness of the first A layer being 0.5 m to 3 m, (b) a second A layer made of a TiCo phase and a metal Ti phase is formed adjacent to the first A layer, an average area ratio of the TiCo phase in the second A layer being 50% to 95%, and a thickness of the second A layer being 0.5 m to 3 m, (c) a first B layer made of a TiC phase and a metal W phase is formed adjacent to the WC-based cemented carbide member B, an average area ratio of the TiC phase in the first B layer being 40% to 60%, and a thickness of the first B layer being 0.5 m to 3 m, (d) a second B layer made of a TiCo phase and a metal Ti phase is formed adjacent to the first B layer, an average area ratio of the TiCo phase in the second B layer being 50% to 95%, and a thickness of the second B layer being 0.5 m to 3 m, and (e) a residual Ti layer is present in a central region of the bonding layer sandwiched between the second A layer and the second B layer, and the WC-based cemented carbide member A, the first A layer, the second A layer, the residual Ti layer, the second B layer, the first B layer, the WC-based cemented carbide member B are bonded in an order.

2. The composite member according to claim 1, wherein an area ratio occupied by the metal W phase in the first A layer gradually decreases from the WC-based cemented carbide member A side toward the second A layer side, or an area ratio occupied by the metal W phase in the first B layer gradually decreases from the WC-based cemented carbide member B side toward the second B layer side.

3. The composite member according to claim 1, wherein an area ratio occupied by the metal W phase in the first A layer gradually decreases from the WC-based cemented carbide member A side toward the second A layer side, and an area ratio occupied by the metal W phase in the first B layer gradually decreases from the WC-based cemented carbide member B side toward the second B layer side.

4. A cutting tool constituted by a composite member according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view illustrating a manufacturing process of a composite member of the present invention, in which (a) illustrates the composite member before bonding, (b) illustrates the composite member at the time of solid phase diffusion bonding, and (c) illustrates the composite member after the bonding.

(2) FIG. 2 illustrates an enlarged schematic view of FIG. 1 (c).

(3) FIG. 3 is a schematic view showing a WC-based cemented carbide member, a first layer, a second layer, a residual Ti layer of the composite member of the present invention (an image used for element mapping in a vertical cross section). In the first layer (first A layer (8)), a black area and a white area correspond to TiC and metal W, respectively. In the second layer (second A layer (9)), a light gray area and a dark gray area correspond to TiCo and metal Ti, respectively. In FIG. 3, W content is large at an upper layer side and the W content decreases toward a lower layer side.

DETAILED DESCRIPTION OF THE INVENTION

(4) Hereinafter, the present invention will be described in detail on the basis of an example. The example described below is one embodiment of the present invention, and the present invention is not limited thereto.

EXAMPLE

(5) A WC powder, a VC powder, a TaC powder, a NbC powder, a Cr.sub.3C.sub.2 powder and a Co powder, which had an average grain size of 0.5 m to 1 m, were prepared as raw powders, these raw powders were blended according to a composition formulation shown in Table 1, wet-blended for 24 hours in a ball mill, dried, and press-molded into a green compact under a pressure of 100 MPa, and then this green compact was sintered in a vacuum of 6 Pa at a temperature of 1400 C. for a holding time of 1 hour to form four kinds of WC-based cemented carbide sintered materials (hereinafter simply referred to as cemented carbide) A-1 to A-4.

(6) TABLE-US-00001 TABLE 1 Composition formulation (% by mass) Types Co TaC NbC VC Cr.sub.3C.sub.2 WC Cemented A-1 12 balance carbide A-2 10 1 0.5 balance A-3 12 0.7 balance A-4 8 2 1 balance

(7) Next, a cBN powder, a TiN powder, a TiCN powder, a TiB.sub.2 powder, a TiC powder, an MN powder, and an Al.sub.2O.sub.3 powder, which had an average grain size of 0.5 m to 4 m, were prepared as raw powders of a cBN sintered material, and these raw powders were blended according to a predetermined composition formulation, wet-blended for 24 hours using acetone in a ball mill, dried, and then press-molded into green compacts having dimensions of 15 mm in diameter1 mm in thickness at a pressure of 100 MPa.

(8) Next, the cemented carbides A-1 to A-4 were formed into sintered materials having a diameter of 15 mm and a thickness of 2 mm and were used as a backing material at the time of sintering the cBN sintered material, the cBN green compacts were laminated on the backing material in a combination shown in Table 2, and then the laminates were sintered under conditions of a temperature of 1300 C., a pressure of 5.5 GPa, and a time of 30 minutes using an ultra-high pressure sintering apparatus to manufacture composite sintered materials B-1 to B-4.

(9) Regarding composition of the cBN sintered materials of the composite sintered materials B-1 to B-4, an area % of the cBN was obtained as a volume % by image analysis of scanning electron microscope (SEM) observation results for polished surfaces of cBN sintered material cross sections.

(10) For components other than the cBN, only components constituting a main binder phase and the other binder phases were confirmed. The results are shown in Table 2.

(11) TABLE-US-00002 TABLE 2 Sintered material composition Main Backing cBN binder Types material (volume %) phase Other binder phase Composite B-1 A-1 70 TiN Al.sub.2O.sub.3, TiB.sub.2, AlN, sintered inevitable impurities material B-2 A-2 76 TiN Al.sub.2O.sub.3, TiB.sub.2, AlN, inevitable impurities B-3 A-3 63 TiCN Al.sub.2O.sub.3, TiB.sub.2, AlN, inevitable impurities B-4 A-4 72 TiC Al.sub.2O.sub.3, TiB.sub.2, AlN, inevitable impurities

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

(13) Next, the bonding members between the cemented carbides A-1 to A-4 and the composite sintered materials B-1 to B-4 are shown in Table 3.

(14) With the bonding members inserted and interposed, the composite sintered materials and the cemented carbides were pressurized and bonded under conditions shown in Table 4, that is, under conditions of using a Ti foil having a thickness of 1 m to 50 m as a bonding member, holding them at a predetermined temperature within a range of 600 to 900 C. for 5 to 600 minutes in a vacuum of 110.sup.3 Pa or less, and applying a pressure of 0.5 to 10 MPa, and thereby composite members 1 to 9 of the present invention shown in Table 6 were manufactured. Each of the composite sintered materials was disposed such that the cBN sintered material was on an outer surface and the backing material was on an inner surface, that is, disposed such that the WC-based cemented carbide serving as a backing material and the WC-based cemented carbide serving as a tool body (base body) were bonded via a bonding member.

(15) For comparison, bonding members having the sizes shown in Table 3 were used and inserted and interposed between the cemented carbides A-1 to A-4 and composite sintered materials B-1 to B-4, respectively, and the composite sintered materials and the cemented carbides were pressurized and bonded under the conditions shown in Table 5 to manufacture composite members 1 to 10 of comparative examples shown in Table 7. A bonding arrangement of the composite sintered material was the same as that of the composite member of the present invention.

(16) TABLE-US-00003 TABLE 3 Types Bonding member C-1 foil thickness Ti foil of 4 m C-2 foil thickness Ti foil of 20 m C-3 foil thickness Ti foil of 50 m C-4 foil thickness Ti foil of 80 m C-5 foil thickness Ti foil of 150 m C-6 a brazing material having a composition of Ti 25%, Zr 25%, Cu 50%

(17) TABLE-US-00004 TABLE 4 Composite Bonding conditions Cemented sintered Bonding Bonding Holding Pressurizing Atmosphere carbide material member temperature time load pressure Types types types types ( C.) (min.) (MPa) (Pa) Composite 1 A-1 B-1 C-1 800 30 2 1 10.sup.3 member of 2 A-2 B-2 C-2 700 120 5 1 10.sup.3 present 3 A-3 B-3 C-3 900 5 0.5 1 10.sup.1 invention 4 A-4 B-4 C-1 600 600 10 1 10.sup.1 5 A-1 B-4 C-2 750 60 7 1 10.sup.3 6 A-2 B-3 C-3 650 300 3 1 10.sup.3 7 A-3 B-2 C-4 850 15 7 1 10.sup.1 8 A-4 B-1 C-2 700 180 5 1 10.sup.3 9 A-1 B-2 C-5 800 45 3 1 10.sup.3

(18) TABLE-US-00005 TABLE 5 Composite Bonding conditions Cemented sintered Bonding Bonding Holding Pressurizing Atmosphere carbide material member temperature time load pressure Types types types types ( C.) (min.) (MPa) (Pa) Composite 1 A-1 B-1 C-1 1000 5 2 1 10.sup.3 member of 2 A-2 B-2 C-2 500 600 5 1 10.sup.3 comparative 3 A-3 B-3 C-3 600 1000 0.5 1 10.sup.1 example 4 A-4 B-4 C-1 900 2 10 1 10.sup.1 5 A-1 B-4 C-2 750 60 0 1 10.sup.3 6 A-2 B-3 C-3 650 300 0 1 10.sup.3 7 A-3 B-2 C-5 1000 30 7 1 10.sup.1 8 A-4 B-1 C-4 1000 120 5 1 10.sup.3 9 A-1 B-2 C-5 500 1200 3 1 10.sup.3 10 A-1 B-1 C-6 850 30 0 1 10.sup.3

(19) High Temperature Shear Strength Measurement Test:

(20) For the composite members 1 to 9 of the present invention and the composite members 1 to 10 of the comparative example manufactured above, a shear strength measurement test was performed to measure strength of the bonding portion.

(21) Test pieces used for the test were obtained from the composite members 1 to 9 of the present invention and the composite members 1 to 10 of the comparative example by cutting the composite sintered material into a size of 1.5 mm (W)1.5 mm (L)0.75 mm (H) and by cutting the WC-based cemented carbide body (base body) into a size of 1.5 mm (W)4.5 mm (L)1.5 mm (H), and were used as the shear strength measurement test pieces.

(22) Upper and lower surfaces of the test piece were gripped and fixed by a clamp, a load was applied near an approximate center of the upper surface of the test piece using a prismatic pressing piece made of cemented carbide with one side of 1.5 mm in an atmosphere temperature of 600 C., and a load at which the test piece broke was measured.

(23) Table 6 and Table 7 show measured values of the shear strength.

(24) In addition, for the composite members 1 to 9 of the present invention and the composite members 1 to 10 of the comparative example, a composition analysis of the vertical cross section of the bonding portion with the WC-based cemented carbide was performed using a scanning electron microscope and an energy dispersive X-ray spectrometer.

(25) FIG. 3 shows a schematic view of the WC-based cemented carbide member, a first layer, a second layer, a residual Ti layer of the composite member of the present invention (an image used for element mapping in the vertical cross section). In the first layer (first A layer (8)), a black area and a white area respectively correspond to TiC and metal W. In the second layer (second A layer (9)), a light gray area and a dark gray area respectively correspond to TiCo and metal Ti. In FIG. 3, a W content is high at an upper layer side and the W content decreases toward a lower layer side.

(26) With an interface between the WC-based cemented carbide member and a bonding layer as the center, element mapping was performed in a range of plus and minus 100 m in a direction perpendicular to the interface, by which a WC phase, a Co phase, a TiC phase, a metal W phase, a TiCo phase and a metal Ti phase were identified, and the cemented carbide member, the first layer, the second layer, and the residual Ti layer were identified. From the result of the element mapping, area ratios occupied by the TiC phase and the TiCo phase were measured.

(27) Regarding the first layer, the first layer was divided into three equal sections of a cemented carbide member side layer, a central layer, and a second layer side layer in a thickness direction, and an area ratio of the metal W phase in each layer was obtained from the element mapping result.

(28) Further, layer thicknesses of the first layer, the second layer and the residual Ti layer were obtained.

(29) A central portion region of the bonding layer containing a Ti content exceeding 90 atomic % was identified as a residual Ti layer.

(30) The first A layer, the second A layer, the residual Ti layer, and results of shear strength are shown in Tables 6 and 8. Measurement results of the first B layer and the second B layer are shown in Tables 7 and 9. Further, for the composite members 1 to 4 of the present invention and the composite members 1 to 4 and 10 of the comparative example, since the first A layer and the first B layer, and the second A layer and the second B layer were substantially equivalent, description of the first B layer and the second B layer was omitted.

(31) TABLE-US-00006 TABLE 6 Bonding layer First A layer (TiC + metal W) Second A layer Change in area ratio of metal (TiCo + metal Ti) Average area W phase (area %) Average area ratio of TiC Carbide Second Layer ratio of TiCo Layer Residual Ti layer Shear phase member side Central layer side thickness phase thickness Layer thickness strength Types (area %) layer layer layer (m) (area %) (m) (m) (MPa) Composite 1 45 72 50 46 1.8 62 1.7 0.4 300 member of 2 50 65 51 37 1.2 65 1.3 15.0 510 present 3 53 47 48 47 3.0 50 3.0 40.0 320 invention 4 47 62 53 42 0.5 72 0.5 2.1 350 5 40 71 60 51 1.3 80 1.3 15.0 470 6 52 65 48 33 0.8 67 0.7 47.0 450 7 60 50 39 30 2.3 95 2.2 71.0 350 8 55 53 45 35 1.4 88 1.5 14.0 480 9 50 65 48 36 2.0 75 2.1 142.0 330

(32) TABLE-US-00007 TABLE 7 Bonding layer First B layer (TiC + metal W) Second B layer Change in area ratio of metal (TiCo + metal Ti) Average area W phase (area %) Average area ratio of TiC Carbide Second Layer ratio of TiCo Layer phase member side Central layer side thickness phase thickness Types (area %) layer layer layer (m) (area %) (m) Composite 5 43 70 57 48 1.1 74 1.1 member of 6 51 66 49 34 0.9 69 0.9 present 7 59 51 41 33 2.1 92 2.0 invention 8 51 55 49 38 1.9 90 2.1 9 52 63 48 35 1.8 72 1.9

(33) TABLE-US-00008 TABLE 8 Bonding layer First A layer (TiC + metal W) Second A layer Change in area ratio of metal (TiCo + metal Ti) Average area W phase (area %) Average area ratio of TiC carbide Layer ratio of TiCo Layer Residual Ti layer Shear phase member center of second thickness phase thickness Layer thickness strength Types (area %) side first layer layer side (m) (area %) (m) (m) (MPa) Composite 1 30 68 66 72 1.5 43 1.5 0 150 member of 2 68 10 35 50 0.5 95 0.5 18 270 comparative 3 77 23 22 23 3 98 3 38 220 example 4 31 70 70 67 1.5 38 1.5 0 230 5 41 59 60 59 0.3 80 0.3 19 210 6 52 49 48 49 0.2 67 0.2 49 190 7 25 75 70 76 5 42 5 133 130 8 40 59 60 62 20 50 20 10 180 9 80 19 12 30 0.5 97 0.5 148 200 10 250

(34) TABLE-US-00009 TABLE 9 Bonding layer First B layer (TiC + metal W) Second B layer Change in area ratio of metal (TiCo + metal Ti) Average area W phase (area %) Average area ratio of TiC carbide Layer ratio of TiCo Layer phase member center of second thickness phase thickness Types (area %) side first layer layer side (m) (area %) (m) Composite 5 43 61 57 61 0.2 78 0.2 member of 6 54 45 46 45 0.3 71 0.3 comparative 7 22 80 78 75 4.8 40 4.7 example 8 44 54 56 58 18 47 18 9 78 24 22 21 0.3 95 0.3

(35) Next, cutting tools made of the composite members 1 to 9 of the present invention and the composite members 1 to 10 of the comparative example were manufactured, and presence or absence of occurrence of breakage in cutting was investigated.

(36) The cutting tools made of the composite members were manufactured as below.

(37) The composite sintered materials B-1 to B-4 manufactured above were cut into dimensions of a planar shape of an isosceles triangle having a side of 4 mm at an insert included angle of 80, and a thickness of 2 mm Subsequently, the cemented carbides A-1 to A-4 were formed into a sintered material having dimensions of a planar shape of a rhombus having a diameter of an inscribed circle of 12.7 mm at an insert included angle of 80 and a thickness of 4.76 mm, and a notch having a size corresponding to a shape of the composite sintered material was formed using a grinding machine at one corner of any surface in upper and lower surfaces parallel to each other in the sintered material. An area of a bottom surface of this notch was 2.96 mm.sup.2 and an area of a side surface was 4.89 mm.sup.2. Next, the bonding members shown in Table 3 were inserted and interposed between the cemented carbides A-1 to A-4 and the composite sintered materials B-1 to B-4, the composite sintered materials and the WC-based cemented carbides were pressurized and bonded under conditions shown in Table 4, the composite member was subjected to outer periphery polishing processing, then cutting edge portion was subjected to honing processing of R: 0.07 mm, and thereby cutting tools 1 to 9 of the present invention having an insert shape of ISO standard CNGA 120408 were manufactured.

(38) Further, the composite sintered material was disposed such that the cBN sintered material was on the outer surface and the backing material was on the inner surface, that is, the backing material and the tool body (base body) were bonded via the bonding member.

(39) In addition, it was confirmed that the bonding 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.

(40) Similarly, the bonding members shown in Table 3 were inserted and interposed between the composite sintered materials B-1 to B-4 manufactured above and the cemented carbides A-1 to A-4 manufactured above, which were pressurized and bonded under the conditions shown in Table 5 to manufacture cutting tools 1 to 10 of the comparative example.

(41) In addition, it was confirmed that the bonding portions of the cutting tools 1 to 10 of the comparative example were substantially the same as the composite members 1 to 10 of the comparative example shown in Table 7.

(42) Next, in a state in which all the above various types of cutting tools were each screwed to a distal end portion of an insert holder of tool steel using a fixing jig, a dry high-speed cutting test of carburized steel to be described below was performed on the cutting tools 1 to 9 of the present invention and the cutting tools 1 to 10 of the comparative example, and falling of a cutting edge tip and a location of the broken part were observed.

(43) Work Material: Round bar of JISSCM 415 (hardness: 58 HRc)

(44) Cutting speed: 250 m/min,

(45) Depth of cut: 0.4 mm,

(46) Feed: 0.2 mm/rev.,

(47) Cutting time: 16 minutes,

(48) (Normal cutting speed is 150 m/min),

(49) Results of the cutting test are shown in Table 10.

(50) TABLE-US-00010 TABLE 10 Falling Falling of a cutting of a cutting Types edge tip Types edge tip Breakage location Tools of 1 No Tools of 1 Yes Interface between first layer and second present comparative layer invention 2 No examples 2 Yes Interface between first layer and cemented carbide member 3 No 3 Yes Interface between first layer and cemented carbide member 4 No 4 Yes Interface between second layer and residual Ti layer 5 No 5 Yes Interface between first layer and cemented carbide member 6 No 6 Yes Interface between first layer and cemented carbide member 7 No 7 Yes Interface between first layer and second layer 8 No 8 Yes Interface between second layer and residual Ti layer 9 No 9 Yes Interface between first layer and cemented carbide member 10 Yes Inside brazing material

(51) From values of the shear strength shown in Tables 6 and 8, it was understood that the composite members 1 to 9 of the present invention have superior bonding strengths as compared with the composite members 1 to 10 of the comparative example.

(52) Also, it was understood from results shown in Table 10, the cutting tools 1 to 9 of the present invention formed of the composite members 1 to 9 of the present invention exhibit excellent cutting performance for long-term usage without the cutting edge tip falling, while the cutting tools 1 to 10 of the comparative example formed of the composite members 1 to 10 of the comparative example show that each of the cutting edge tips falls from the bonding portion during cutting and the tool life comes to an end at an early stage.

(53) Although a specific description using the insert as an example was presented in the present embodiment, the present invention is not limited to the insert, and can be applied to all cutting tools having a bonding portion between a cutting edge portion and a tool body such as a drill, an end mill, or the like, and can be applied to an excavating tool such as a bit.

INDUSTRIAL APPLICABILITY

(54) The composite member of the present invention has high bonding strength, and the cutting tool manufactured from the composite member can be used for high load cutting of various kinds of steel or cast iron, and furthermore, since the cutting tool exhibits stable cutting performance for long-term usage, it can satisfy requirements of high performance of a cutting apparatus, labor saving of cutting, energy saving, and also cost reduction.

(55) While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.

EXPLANATION OF REFERENCES

(56) 1: WC-based cemented carbide member A

(57) 2: WC-based cemented carbide member B

(58) 3: Bonding member (Ti foil)

(59) 4: Pressure

(60) 5: Solid phase diffusion bonding

(61) 6: Composite member

(62) 7: Bonding layer

(63) 8: First A layer (TiC+metal W)

(64) 9: Second A layer (TiCo+metal Ti)

(65) 10: Residual Ti layer

(66) 11: Second B layer (TiCo+metal Ti)

(67) 12: First B layer (TiC+metal W)