JPS6017017B2 - Tungsten carbide-based sintered cemented carbide - Google Patents

Description

Detailed Description of the Invention The present invention has excellent wear resistance, heat resistance, and plastic deformation resistance, as well as particularly excellent fracture resistance. This article relates to WC-based sintered cemented carbide, which exhibits outstanding cutting performance in high-speed cutting, cutting of high-hardness materials, and cutting of difficult-to-cut materials, which are disadvantages of tungsten (hereinafter referred to as WC)-based sintered cemented carbide. be.

The WC-based hardened carbide for cutting tools is classified into WC-Co based carbide, which belongs to the K series of the JIS classification, and WC-(W,Ti)C-(Ta), which belongs to the P and M series of the JIS classification. ,N
b) It has been broadly classified into C-Co based cemented carbide.
Generally, for high-speed cutting, WC-(W,Ti)C-(T
a, Nb) Among C-Co type cemented carbides, (W, T
i) A PIO grade material containing a large amount of C and (Ta,Nb)C and having excellent wear resistance and heat resistance is used.

However, this alloy suffers from severe wear during high-speed cutting at a cutting speed of over 200 cuts/min, making it impractical for practical use. In addition, when cutting high-hardness materials with a Rockwell hardness (C scale) of 50 or higher, which generates a large amount of heat and places large stress on the cutting edge, it is necessary to have high cutting edge strength, heat resistance, and plastic deformation resistance. Although it is desired to use an alloy rich in WC-(W,Ti)C-(Ta,Nb
) C-Co aged cemented carbide does not exhibit sufficiently satisfactory cutting performance. Furthermore, cutting materials such as Ni-based or Co-based heat-resistant alloys using the above-mentioned WC-based competitive cemented carbide cutting tools is difficult due to the lack of plastic deformation resistance and chipping resistance. In most cases this is not possible. Therefore, from the above-mentioned viewpoint, the present inventors focused on the above-mentioned conventional WC-based sintered cemented carbide used as a material for cutting tools, and applied it to high-speed cutting, high-hardness material cutting, and key cutting. As a result of our research, we found that the conventional WC-based sintered cemented carbide mentioned above should have excellent wear resistance, heat resistance, plastic deformation resistance, and chipping resistance to enable cutting of cutting materials. 2 to 20% of cubic boron (hereinafter referred to as CBN) having an average grain size of 0.5 to 10 as a dispersed phase forming component.
In addition, the surrounding area of the CBN grains is 0.05 to 3
Ti forms an enclosing phase surrounded by the average layer thickness of the enemy.
of carbides, nitrides, and oxides, as well as solid solutions thereof (hereinafter collectively referred to as CBN surrounding phase-forming components), in an amount of 0.1 to
When containing 20% (all percentages are by weight), the resulting WC-based sintered cemented carbide has excellent wear resistance, heat resistance, and plastic deformation resistance.
They found that it has particularly excellent fracture resistance.

Therefore, this invention was made based on the above findings, and CBN: 2 to 2 as a dispersed phase forming component.
0%, surrounding phase forming component of CBN: 0.1 to 20%, carbides of Tj, Ta, and Nb as dispersed phase forming components,
One or more of the group consisting of nitrides (hereinafter collectively referred to as metal carbon/nitrides): 1 to 30%
, one or more iron group metals as a binder phase forming component: 5 to 25%, WC as a dispersed phase forming component and unavoidable impurities: the remainder (WC: 50% or more content). and the average particle size of CBN is 0.
5 to 10 Buddhas, and the average layer thickness of the surrounding phase is 0.05
This is a characteristic feature of a WC-based sintered cemented carbide having a structure with ~3 peaks.

Next, the reason why the component composition, average grain size of CBN, and layer thickness of the surrounding phase are limited as described above in the WC-based competitively bonded cemented carbide of the present invention will be explained.

'a} CBN content and its average particle size When the content is 2% end flow and the average particle size is less than 0.5rm, the desired wear resistance, heat resistance, and plastic deformation resistance cannot be secured. On the other hand, even if its content exceeds 20% or its average particle size exceeds 10 mm, the anti-setting property deteriorates, and cavities are more likely to form in the alloy structure, resulting in a decrease in impact resistance. Therefore, the content was set at 2 to 20%.

'b} CBN surrounding phase forming component content and its average layer thickness When the content is less than 0.1%, the surface of the CBN grains has an average layer thickness of 0.05 degrees or more in relation to its average grain size. Since the desired excellent fracture resistance cannot be ensured, on the other hand, if the content exceeds 20%, the average layer thickness of the surrounding phase becomes thicker than 3 μm. If the content is too high, CBN will be inhibited from fully demonstrating its excellent properties, so the content should be reduced to 0.1.
~20%, and the average layer thickness was determined to be 0.05 to 3 mm.

'c} Carbon/nitride content of metal If the content is less than 1%, the desired wear resistance cannot be secured, while if the content exceeds 30%, the fracture resistance will decrease. Therefore, the content is 1~
It was set at 30%.

Note that the same characteristics can be obtained whether these components are contained in the form of a single substance or in the form of a composite compound. {d} Iron group metal content If the content is less than 5%, it is difficult to secure the desired excellent fracture resistance, while if the content exceeds 25%, wear resistance and heat resistance The content was determined to be 5 to 25%, since the properties of aluminum and plastic deformation resistance deteriorate.

'e' WC Content If the content is less than 50%, the excellent fracture resistance of WC cannot be ensured, so the lower limit of the WC content was set at 50%.

The WC-based sintered cemented carbide of the present invention uses, as one of the essential raw material powders, CBN powder whose surface is coated with an surrounding phase forming component by a normal physical vapor deposition method or chemical vapor deposition method. Instead of using high pressure (20Kb or more), we use the normal powder metallurgy method, that is, we grind and mix raw material powders, press-form a compact from the resulting mixed powder, and then press-form the compact in a vacuum or under 200 atm. It can be produced by scaling in a non-oxidizing atmosphere. Next, the WC-based sintered cemented carbide of the present invention will be explained using examples and comparing with comparative examples.

Example 1 As raw material powders, WC powder with an average particle size of 2.2mm and (W,Ti)C powder (WC/
TIC=70%/30%), same 1.2 mountain surface Ta,N
b) C powder (TaC/N ratio = 90%/10%), same as 1.
Using Co powder with a 2R surface and CBN powder with a 2.5-layer surface coated with TICN with an average layer thickness of 0.3 μm on the surface by the ion plating method as the surrounding phase forming component, these raw material powders were The composition shown in Table 1 was blended, pulverized and mixed in a ball mill, the resulting mixed powder was molded into a sho powder, and then this green compact was heated in a vacuum at a temperature of 1
Alloys 1 to 1 of the present invention having substantially the same composition as the blended composition were obtained by holding at 450°C for 1 hour and binding.
4 and Comparative Alloys 1 to 4 were manufactured, respectively.

Comparative alloys Table 1, Table 2, Tables 1 to 4 all contain compositions in which one of the alloy constituents (indicated with an asterisk in Table 1) is outside the scope of the present invention. It is something that has.

Next, CIS (Cemented Carbide Tool Standard) and SNP were prepared from the resulting Invention Alloys 1 to 4 and Comparative Alloys 1 to 4, as well as PI River Alloy, which is conventionally known as a material for cutting tools.
432, and conducted continuous and interrupted cutting tests under the cutting conditions shown in Table 2. Flank wear and crater wear were measured in the continuous cutting tests. In the intermittent cutting test, it was determined how many of the six test chips had defects. The results of these measurements are shown in Table 3. As shown in Table 3, comparative alloys 1 to 4 and subordinate PI
O alloys have poor wear resistance and chipping resistance, whereas alloys 1 to 4 of the present invention all have excellent wear resistance and chipping resistance, and are extremely good. It is clear that cutting performance can be obtained.

Table 3 Example 2 As raw material powders, WC powder with an average particle size of 3.5 grains and (W,Ti)C powder (WC/Ti) with an average particle size of 1.5 grains were used.
TIC=70%/30%), 1.2〃Skin (Ta, N
b) C powder (TaC/N ratio = 60%/40%), same as 1.
5R skin TIN powder No. 4 At the end of the table, 1.2 μm Co powder, 2.7 μm skin Ni powder, and average layer thickness: 0.4 Buddha TIC and TIN on the surface respectively by ion plating method. Using two types of CBN powders of the same 2.0 mm coated with CBN as an surrounding phase forming component, these raw powders were blended into the composition shown in Table 4, pulverized and mixed in a ball mill, and this A green compact is formed from the resulting mixed powder, and then this green compact is held at a temperature of 140,000 for 1 hour in an N2 atmosphere at a pressure of 20 Torr to form a green compact with substantially the same composition as the blended powder. Invention alloys 5 to 8 and comparative alloys 5 and 6 having the following compositions were manufactured, respectively.

Note that Comparative Alloy 5 has a high Co content that is outside the range of the present invention, and Comparative Alloy 6 does not contain CBN. Next, from the resulting alloys of the present invention 5 to 8, comparative alloys 5 and 6, and alloy P3, which is conventionally known as a material for cutting tools, chips for cutting tests with shapes conforming to CIS/SPP422 were manufactured. Work material: Inconel 718 Work material shape: Diameter 20, Ratio 0 x Length 50
One with 0 rib dimensions and two longitudinal grooves of 15 depth x 15 width on opposite sides in the longitudinal direction, honing of cutting edge: 0.1 rib x 25o, transverse edge angle: 75o, cutting speed: 50/min, feed: 0.1 rib/rev. , Depth of cut: 1. Flank wear and crater wear were measured by conducting a continuous cutting test on the base cutting material under conditions of 1 skin inch cutting time.

These measurement results are shown in Table 5 together with the wear conditions.
As shown in Table 5, alloys 5 to 8 of the present invention have superior wear resistance, plastic deformation resistance, and chipping resistance compared to comparative alloys 5 and 6 and the conventional P3 alloy. It is clear that it has a sexual nature.

Example 3 As raw material powders, WC powder with an average particle size of 4.0 TIC and (W,Ti)C powder (WC/TIC with an average particle size of 1.5 TIC) were used as raw material powders.
=70%/30%), same 1.4 Buddha skin W, Ti)CN
Powder (WC/TIC/TIN=50%/30%/20%
), (Ta,Nb)C powder (TaC/N
Ratio = 90%/10%), TaN powder of Table 6 of 1.5 m, NbN powder of 1.7 m, Co powder of 1.2 m, and average layer thickness by chemical vapor deposition, respectively. : Two types of CBN powders having the same 1.5 〆 skin coated with 0.2rm TIC○ and TICNO as surrounding phase forming components were used, and these raw material powders were blended into the composition shown in Table 6. The resulting green compacts were pulverized and mixed in a pole mill, and then molded into green compacts.
By holding at 50°C for 1 hour and sintering, alloys 9 to 1 of the present invention having substantially the same composition as the blended composition are obtained.
Comparative Alloy 2 and Comparative Alloy 7, which did not contain CBN as an alloy component, were manufactured.

Next, chips were manufactured from the resulting alloys 9 to 12 of the present invention and comparative alloy 7, as well as an M2 alloy conventionally known as a material for cutting tools, under the same conditions as in Example 1. Cutting material: SKD-61 (HRC53),
Work material dimensions: width 5 broadside x length 500 ribs, cutter shape: face milling cutter (double positive, cut length: 16
◇, Number of blades: 8), Cutting speed: 100/min,
A milling test on hardened materials was conducted under the following conditions: feed per tooth: 0.15 skin/tooth, depth of cut: 3.0 ribs, and cutting time: 2 h. The number of thermal cracks that occurred was measured.

The measurement results are shown in Table 7. Table 7 As shown in Table 7, Alloys 9 to 12 of the present invention have better wear resistance, chipping resistance, and thermal cracking resistance than Comparative Alloy 7 and the conventional M2 alloy. It is excellent in

As is clear from the above results, the WC-based sintered cemented carbide of the present invention has excellent wear resistance, heat resistance, plastic deformation resistance, and chipping resistance, so it is particularly suitable for cutting tools. It exhibits excellent cutting performance not only in general cutting, but also in high-speed cutting, cutting of high-hardness materials, and difficult-to-cut machining, which conventional WC-based cemented carbides are weak at. It is something.

Claims (1)

[Claims] 1 Cubic boron nitride as a dispersed phase forming component: 2-2
0%, T as an ambient phase forming component of cubic boron nitride
One or more of the group consisting of carbides, nitrides, carbonitrides, carbonates, and carbonitrides of i: 0.1
~20%, one or more of the group consisting of carbides and nitrides of Ti, Ta, and Nb as dispersed phase forming components: 1 to 30%, iron group metals as binder phase forming components One or more of: 5 to 25%,
It has a composition (more than 50% by weight) consisting of tungsten carbide as a dispersed phase forming component and unavoidable impurities (however, tungsten carbide: 50% or more content), and the average particle size of cubic boron nitride is 0.5 A tungsten carbide-based sintered cemented carbide having a structure in which the average layer thickness of the surrounding phase is 0.05 to 3 μm.