JPS607020B2 - High toughness cermet for cutting tools - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cermet that has high ballability and exhibits excellent cutting performance when used as a cutting tool, especially for heavy cutting such as high-feed cutting and deep-cut cutting. .

Conventionally, composite metal carbonitrides of Tj and W (hereinafter referred to as (T)) have been used as cermets for cutting tools.
A cermet in which i, W) (denoted as CN) is dispersed in W as a bonding phase forming component is known, but this conventional cermet is
Competitive sintering at a temperature exceeding 2000 oo is necessary for complete sintering, and therefore the hard dispersed phase (Ti, W)C
There was a drawback that N and W in the binder phase grew grains and formed arms.

Therefore, when this material is used for heavy cutting of steel, etc., which particularly requires ballability, it is not used for such heavy cutting because it breaks due to lack of ballability. From the above-mentioned viewpoints, the present inventors have proposed that by interposing a substance between W particles, which itself has good durability, has excellent wear resistance and heat resistance, and also has good bonding properties with W. As a result of various studies to refine the particles of the hard dispersed phase and binder phase of the above cermet and improve its toughness, we found that the above cermet has aluminum nitride (hereinafter referred to as AIN), nitride nitride, and elemental (hereinafter referred to as Si3N4). When one or more of carbonized poppy, carbonized poppy, and element (hereinafter referred to as SIC) are contained as a dispersed phase, the sintering property of W is further improved and a completely sintered body can be obtained at a relatively low temperature. As a result, the particles of the hard dispersed phase and binder phase of the cermet become finer, resulting in improved toughness, and when titanium nitride (hereinafter referred to as TIN) is added to the cermet, the particles become even finer. They found that the toughness was further improved.

This invention was made based on the above knowledge, and (Tj "W) CN: 15 to 45% by weight, NN, Si
One or more of 3N4 and SIC: 0.
Contains 5-5% by weight, and if necessary, TIN: 1-1% by weight, with the remainder consisting of W and unavoidable impurities, especially for heavy cutting of cast iron, steel, etc. When used as a tool, this cermet is characterized by excellent wear resistance and high grain hardness.

Next, the reason for limiting the component composition range as described above in the cermet of the present invention will be explained.

{a) (Ti, W) CN This component is a main hard dispersed phase forming component, has the effect of imparting wear resistance, and has extremely good burning streak resistance with W, and has good high-temperature properties. It is excellent, but its content is 15
If the content is less than 45% by weight, the desired abrasion resistance cannot be secured, while if the content exceeds 45% by weight, the amount of W becomes too small, resulting in insufficient ballability. The content was determined to be 15 to 45% by weight.

[b) Mountain N, Si3N4, SIC These components have a sintering accelerating effect of W itself, so they are heated at relatively low temperatures (200
As a result, the grain growth of both the hard dispersed phase and the binder phase is suppressed and the toughness is improved, but if the content is less than 0.5% by weight,
The above-desired effects cannot be obtained, and if the content exceeds 5% by weight, the areas where these components, which are inherently difficult to sinter, will agglomerate will increase, resulting in a decrease in toughness. was determined to be 0.5 to 5% by weight.

{c} TIN When this component is used in combination with one or more of the above-mentioned MN, Si3N4, and SIC, it has the effect of further contributing to suppressing grain growth of W during the firing process and further improving toughness. However, if the content is less than 1% by weight, the desired improvement effect cannot be obtained;
If the content exceeds 10%, contact points between the TIN particles will occur, and the ballability will deteriorate, so the content was set at 1 to 1Q% by weight.

The cermet of the present invention can be manufactured according to the usual powder metallurgy method, but in particular, the following methods:
First, (Ti, W) CN, NN, Si3N4, SIC
Prepare TIN and W powders, and mix one or more of AIN powder, Si3N4 powder, and SIC powder, W powder, and TIN powder as necessary with the (Ti, W)CN powder. After wet-mixing under normal conditions, drying, and molding to form a green compact, it was heated in vacuum in an argon or nitrogen atmosphere at a temperature of about 2,200 ml.
It may be calcined under atmospheric pressure or hot pressed with CO, or it may be condensed in a hydrogen atmosphere up to a temperature of about 1200°C and then sintered in vacuum in an argon or nitrogen atmosphere at a higher temperature; Depending on temperature: 1600-200000, pressure: 1000-200
It is preferable to manufacture by hot isostatic pressing in an argon or nitrogen atmosphere under conditions of tm.

Next, the cermet of the present invention will be specifically explained using Examples.

Example First, as a raw material powder, commercially available average grain Mugwort: 1.
(Ti, W) CN powder with 0.5 m, NN powder with 0.8 m, Si3N4 powder with 0.7 m.

5 SIC powder, 1.2 French TIN powder, and 1.2 French W powder were prepared, and these raw powders were blended into the composition shown in Table 1, and wet-processed in acetone. After mixing in a pole mill for 7 hours and drying under reduced pressure,
The green compact is molded into a green compact under the pressure of
- After heating in a 3 ton vacuum until the temperature reached 1,400°C, the atmosphere was changed to a nitrogen atmosphere at normal pressure, and the temperature was held at 1,900,000°C for 1 hour.
Cermets 1 to 21 of the present invention having substantially the same composition as the blended composition were manufactured.

Furthermore, for comparison, those whose compositions have compositions in which the content of any one of the constituent components (marked with * in Table 1) is outside the scope of the present invention, nail N, Si3N4, and SIC.
Conventional cermets containing none of the above, ie, Comparative Cermets 1 to 7, were manufactured under the same conditions as above. Next, the hardness (Rockwell hardness A scale) and transverse rupture strength of each cermet obtained as a result were measured, and a cutting tip was cut from it. Work material: SNCM-8 (hardness: HB270) A high-speed cutting test was conducted on steel under the following conditions: cutting speed: 160 m/min, feed: 0.45 side'rev., depth of cut: 2 legs, cutting time (T): 15 min. It was measured.

Also, workpiece material: SNCM-8 (hardness: HB270, dimensions 500 feet x 300 skin x 15 pieces of board material), cutting speed: 1
00/mjn, depth of cut: 2 Yanagi, the feed amount was changed under the conditions, and if the cutting tip did not break at each feed: 2 minutes, the feed amount was increased sequentially. Cutting without breaking. The cutting rutting property was evaluated using the maximum feed possible. The results of these measurements are shown in Table 1.

Table 1-1 Table 1-2 From the results shown in Table 1, the present invention cermets 1 to 21
All of these cermets have higher hardness and ballability than Comparative Cermets 1 to 7, and exhibit excellent wear resistance and cutting rut resistance when used as cutting tools, and are suitable for heavy cutting of steel, etc. It is clear that it is well tolerated.

As mentioned above, the cermet of the present invention has particularly excellent toughness and wear resistance, so it can be used as a cutting tool for heavy cutting such as high-feed cutting and deep-cut cutting, where these characteristics are particularly required. It shows excellent performance in many cases.

Claims (1)

[Claims] 1. Composite metal carbonitride of Ti and W: 15 to 45% by weight,
A cutting tool containing 0.5 to 5% by weight of one or more of aluminum nitride, silicon nitride, and silicon carbide, with the remainder consisting of W and unavoidable impurities. High toughness cermet. 2 Composite metal carbonitride of Ti and W: 15 to 45% by weight,
A composition containing one or more of aluminum nitride, silicon nitride, and silicon carbide: 0.5 to 5% by weight, titanium nitride: 1 to 10% by weight, and the remainder consisting of W and inevitable impurities. A high-toughness cermet for cutting tools, characterized by comprising: