JPS586775B2 - Cermet for cutting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cermet that exhibits excellent cutting performance not only in high-speed cutting but also in heavy cutting such as milling.

Conventionally, titanium carbide (hereinafter T
Previously, cermets mainly composed of titanium nitride (hereinafter referred to as TiN) were the main component, and cermets containing TiC as the main component have recently been introduced. Examples include those in which TiN is substituted for TiN, and those in which titanium carbonitride (hereinafter referred to as TiCN) is the main component.

However, the above-mentioned TiC-based cermets are inferior in toughness to WC-based alloys, etc., and cermets in which a part of the above-mentioned main component TiC is replaced with TiN and TiCN-based cermets Although alloy defects such as bores and cavities are less likely to occur in the alloy, since the hard phase is mainly TiC, there has been no substantial improvement in strength, and the toughness is still not sufficient. is not.

Furthermore, in the above TiN-based cermet,
Due to alloy defects such as bores and cavities, sufficient strength cannot be obtained in the binder phase, and the strength decreases particularly at high temperatures.

For this reason, the current situation is that none of the above-mentioned cermets can be expected to be used satisfactorily as a cutting tool in cutting forms where impact is applied.

From the above-mentioned viewpoints, the present inventors have discovered that the material has high strength at room temperature and high temperature, as well as excellent toughness, flank wear resistance, crater resistance, and oxidation resistance.
As a result of research to obtain a cermet particularly suitable for use as a cutting tool, we found that: (1) The main part of the hard phase is one or more of Ta, Nb, and Zr carbonitrides = 5 ~50% by weight, the rest consists of TiCN, N/C weight ratio: 1/
When composed of multiple solid solution carbonitrides with a ratio of 10 to 2/1,
The generation of decomposed nitrogen during vacuum sintering in alloy production is extremely reduced, so that a cermet which has no alloy defects, is rich in wear resistance, and is solid solution strengthened and toughened.

(2) When one or more of tungsten carbide (hereinafter referred to as WC), metallic tungsten (W), molybdenum carbide (Mo2C), and metallic molybdenum (Mo) is added and contained, the main part of the hard phase becomes Grain growth of certain of the plurality of solid solution carbonitrides is suppressed, and the wettability of Al and a binder phase made of ferrous metals is improved, thereby improving sinterability.

The findings shown in sections (1) and (2) above were obtained.

Therefore, the present invention has been made based on the above findings, and the present invention is based on the above-mentioned findings, and includes a cermet containing (a) one or more of the group consisting of W, Mo, and carbides of these: 10% by weight; ~40%, (b) Ta,
Contains one or more of the group consisting of carbonitrides of Nb and Zr: 5 to 50%, with the remainder consisting of TiCN, N/C weight ratio: 1/10 to 2/1 Multiple solid solution carbonitrides with: 30-85%, (c) Al: 0.05-3%, (a) Iron metals and inevitable impurities: 4.95-27%
, and is characterized in that the components (a) and (b) above form a hard phase, and the components (c) and (d) above form a binder phase.

Next, the reason for limiting the component composition and N/C weight ratio as described above in the cermet of the present invention will be described.

(1) Multiple solid solution carbonitrides ■ N/C weight ratio If the weight ratio exceeds 2/1, the amount of N relative to C becomes too large and nitrogen decomposition occurs during vacuum sintering in cermet manufacturing. As a result, defects such as pores and cavities will occur and the strength will decrease, so the N/C ratio must be below the upper limit.

However, if the N/C ratio is less than 1/10, C to N
If the amount of nitride becomes too large, it becomes impossible to ensure the excellent crater resistance and thermal cracking resistance of the nitride, so the N/C ratio must be greater than the lower limit value.

■Content of carbonitrides of Ta, Nb, and Zr Carbonitrides of these components have the effect of solid solution strengthening of the cermet, but if the content is less than 5%, the desired effect is not achieved. cannot be obtained, so it is necessary to contain 5% or more.
If the content exceeds 0%, wear resistance will deteriorate, so the content should not exceed 50%.

■Content of multiple solid solution carbonitrides If the content is less than 30%, it will not be possible to obtain a cermet with high wear resistance, solid solution strengthening, and high toughness. is necessary.

However, if the content exceeds 85%, the binder phase content becomes relatively too small and the cermet itself becomes brittle and cannot be used. Therefore, the content should not exceed 85%.

(2) Content of W, Mo, and these carbides If the content is less than 10%, the grain growth of multiple solid solution carbonitrides is suppressed, the wettability of this with the binder phase, and sintering during cermet manufacturing. Since the desired effect of improving properties cannot be obtained, it is necessary to contain the above lower limit or more.

However, if the content exceeds 40%, decomposed nitrogen is likely to be generated from multiple solid solution carbonitrides during hard phase formation, and as a result, pores and cavities are likely to be formed, resulting in a decrease in strength and wear resistance. The content should not exceed the above upper limit because it will cause deterioration.

(3) Al content When Al is included in the binder phase, Ni3Al(Ti) type intermetallic compounds are finely precipitated and the binder phase is strengthened, but if the content is less than 0.05%, the binder phase is strengthened. The above-mentioned strengthening cannot be sufficiently achieved, and on the other hand, if the content exceeds 3%, brittle phases such as NiAl, CoAl, and FeAl will precipitate, which is undesirable. It was set at 0.05 to 3%.

(4) Content of ferrous metals If the content is less than 4.95%, the desired toughness cannot be secured, so the content must exceed the lower limit value above, but if the content exceeds 27% The content should not exceed the above upper limit as this will deteriorate the wear resistance.

The raw materials for forming the plurality of solid solution carbonitrides used in the production of the cermet of the present invention include, for example, a carbide of one or more of TiC, Ta, Nb, and Zr; or a double carbide obtained by high temperature treatment of a mixture of these carbides,
A method of reacting in a high temperature nitrogen atmosphere to form a solid solution, b Ti and one or two of Ta, Nb and Zr
N/C weight ratio: 1/10 to 2/2 of metals, their carbides, nitrides, carbonitrides, and carbon
It can be prepared by a method such as mixing an appropriate amount so as to form a plurality of solid solution carbonitrides having 1 and reacting in a high-temperature vacuum atmosphere or an inert atmosphere to form a solid solution.

Next, the cermet of the present invention will be explained based on examples and compared with comparative cermets.

Multiple solid solution carbonitride powder, TiC powder, T
iN powder, TiCN powder, and 1.2μ W
C powder, W powder of 1.0μ, Mo2C powder of 1.0μ, Mo powder of 0.6μ, Ni powder of 1.0μ, Ni-Al alloy powder of 1.5μ, and 1. 0μ C
After blending an appropriate amount of o powder and pulverizing and mixing in a ball mill, the mixture was sintered by maintaining the temperature in a vacuum at 1400° C. for 1 hour to produce cermets 1 to 3 of the present invention and comparative cermets 1 to 3.

The properties of the cermets 1 to 3 of the present invention and comparative cermets 1 to 3 obtained as a result are shown in Table 2.

Next, dry continuous cutting tests and dry interrupted cutting tests were conducted on the cermets 1 to 3 of the present invention and the comparative cermets 1 to 3 under the cutting conditions shown below, and the results shown in Table 3 were obtained.

■Dry continuous cutting conditions Work material...JIS/SNCM-8, Cutting speed...220m/mm, Feed rate...0.45mm/rev, Depth of cut...2.0mm, Cutting time... 10 minutes, Chip shape: JIS/SNP432 (Honing:
0. I×25°).

■Dry interrupted cutting conditions Work material...JIS/SNCM-8, Cutting speed...100m/mm, Feed rate...0.3mm/rev, Depth of cut...1.5mm, Cutting time... 5 minutes, Chip shape: JIS/SNP432 (honing 0
．． I×25°).

As is clear from the results shown in Table 3, the flank wear width and crater depth in continuous cutting are extremely low in the cermet of the present invention compared to the comparative cermet, and the percentage of cutting edge breakage in interrupted cutting is extremely low. The cermet of the present invention also showed much better results.

As described above, the cermet of the present invention has particularly excellent crater resistance and toughness, and also has oxidation resistance, so it can be used for cutting over a wide range from low speed cutting to high speed cutting. First, it has characteristics suitable for heavy cutting such as milling.

Claims (1)

[Claims] 1 (a) W, Mo, and one or more of these carbides = 10 to 40 rotations (b) One of Ta, Nb, and Zr carbonitrides Or, it contains 5 to 50% of two or more types, and the rest is composed of titanium carbonitride, and the N/C weight ratio: 1/10 to 2/
1: multiple solid solution carbonitrides: 30-85%, (c) Al: 0.05-3%, (d) ferrous metals and unavoidable impurities: 4.95-27%
, (at least % by weight), wherein the components (a) and (b) form a hard phase, and the components (c) and (d) form a bonding phase.