JPH0681071A - Titanium carbonitride based cermet with excellent toughness - Google Patents

Abstract

(57) [Summary] [Objective] To provide a TiCN-based cermet having excellent toughness. A TiCN-based cermet is contained in a weight percentage of one or two of Co and Ni as a binder phase forming component.
Species: 5 to 30%, as a hard phase forming component, Ta, Nb,
Carbides and nitrides of Zr, W, and Mo, and one or more of these solid solutions of two or more:
5 to 30%, similarly TiCN as the hard phase forming component: the remainder, a sintered body having a compounding composition consisting of TiCN grains constituting the hard dispersed phase of this sintered body is rounded and 50% of the TiCN grains. It has a structure composed of spheroidized TiCN grains having an aspect ratio of not less than 1.4 and not more than 1.4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has excellent toughness and, in particular, has excellent performance when used as, for example, a cutting tool for high-speed cutting of steel and various wear-resistant tools required toughness. Titanium carbonitride (hereinafter TiCN)
(Indicated by) for a base cermet.

[0002]

2. Description of the Related Art Conventionally, generally, for example, Japanese Patent Laid-Open No. 2-151
As described in JP-A-39, one or two kinds of Co and Ni as a binder phase forming component: 5 to 30% by weight% (hereinafter,% means% by weight), and a hard phase forming component , Ta, Nb, Zr, W, and Mo carbides and nitrides, and one or more of solid solutions of two or more thereof (hereinafter collectively referred to as metallic carbon / nitride): 5 to 30%, similarly TiCN as the hard phase forming component: the rest, a green compact having a predetermined shape press-molded from a mixed powder having a compounding composition of
It is well known that a TiCN-based cermet composed of a sintered body obtained by sintering at a predetermined temperature within a range of 400 to 1550 ° C. for a predetermined time is used as a cutting tool or various wear resistant tools. It is about to be done.

[0003]

On the other hand, in recent years, the performance and labor saving of various mechanical devices have been remarkable, and for example, in the field of cutting, the cutting speed tends to be high, and in combination with FA and CIM. Therefore, there is a demand for a cutting tool that exhibits a long service life in high-speed cutting.
In the iCN-based cermet, since the toughness is not particularly sufficient, chipping (fine chipping) or chipping is likely to occur in the cutting edge in these high-speed cutting, particularly in high-speed cutting cutting of steel, and it is not possible to satisfy it.

[0004]

Therefore, the present inventors have
From the viewpoints described above, as a result of conducting research to develop a TiCN-based cermet having excellent toughness, focusing on the above-mentioned conventional TiCN-based cermet, the above-mentioned conventional TiCN-based cermet was obtained by the scanning electron microscope of FIG. As shown in the microstructure photograph (4000 times), the TiCN grains (black portion) that make up the hard dispersed phase have a square structure, but the TiCN powder used as the raw material powder for the production of this has a nitrogen atmosphere in advance. Medium, temperature: 1500 to 1700
When the surface modification treatment is performed under conditions of high temperature and high pressure of 60 to 150 MPa at 60 ° C., the TiCN-based cermet produced by using the surface modification treatment is also illustrated in the structural photograph (× 4000) by the scanning electron microscope of FIG. As a result, a study result was obtained that TiCN grains (black portion) forming the hard dispersed phase have a rounded and spheroidized structure, resulting in excellent toughness. Of.

The present invention has been made based on the above-mentioned research results. One or two kinds of Co and Ni as a binder phase forming component: 5 to 30%, and a metallic carbon as a hard phase forming component. One or more kinds of nitrides: 5 to 30%, similarly TiC as a hard phase forming component
N: The remainder is made into a sintered body having a compounding composition, and the TiCN grains constituting the hard dispersed phase of this sintered body are rounded, and 50% by area or more of the TiCN grains have an aspect ratio of 1.4 or less. It is characterized by a TiCN-based cermet having a toughness and having a structure composed of spheroidized TiCN grains having (long axis / short axis).

Next, the composition of the TiCN-based cermet of the present invention and the reason why the aspect ratio and the ratio of the spheroidized TiCN particles are limited as described above will be explained. A. Blending composition (a) Co and Ni These components have the effect of improving the toughness of the cermet, but if the proportion is less than 5%, the desired toughness cannot be obtained, while if the proportion exceeds 30%. Since the wear resistance is lowered, the ratio is set to 5 to 30%.

(B) Metal Carbon / Nitride These components have a function of forming a solid solution of a composite metal carbonitride in the peripheral portion of the TiCN grain and improving the high temperature strength of the cermet, but the proportion thereof is If it is less than 5%, the desired effect cannot be obtained, while if it exceeds 30%, the wear resistance tends to decrease. Therefore, the ratio is set to 5 to 30%.

B. Aspect ratio of TiCN grains and its ratio The degree of spheroidization of TiCN grains in cermet is adjusted by appropriately changing the surface modification treatment conditions for the TiCN powder used as the raw material powder, that is, temperature, pressure, and treatment time. . That is, various kinds of TiCN particles subjected to surface modification treatment under various conditions were used as raw material powders, and WC powder: 5%, Mo ₂ C powder: 5%, and T
aCN powder: 5% (each having an average particle size within the range of 1 to 2 μm) was blended, wet-mixed in a ball mill for 72 hours, dried, and then compacted at a pressure of 1.5 ton / cm ^2. Then, the green compacts were pressed under the same conditions, that is, the temperature rising process up to 1100 ° C. was conducted for 10 ⁻² to
except that a nitrogen atmosphere of rr was used, cooling to room temperature at the end of sintering was performed in a nitrogen atmosphere of 10 torr, and the sintering temperature was 148
Various TiCN-based cermets were produced by sintering at 0 ° C. and holding at this sintering temperature for 1 hour, and the structures of the various cermets obtained as a result were observed by a scanning electron microscope. Observed, the TiCN particles constituting the hard dispersed phase of 1.0 to 1.2, more than 1.2
The ratio of the aspect ratio in the range of 1.4, 1.4 to 1.6, and 1.6 respectively is obtained by image analysis, the fracture toughness value is measured, and the aspect ratio of TiCN grains and The relationship between the ratio and the fracture toughness value was obtained. As a result, it has been empirically found that a TiCN-based cermet having a structure in which TiCN grains having an aspect ratio of 1.4 or less occupy 50 area% or more of the TiCN grains has remarkably excellent toughness. .

[0009]

EXAMPLES Next, the TiCN-based cermet of the present invention will be specifically described by way of examples. First, the TiCN powder having the average particle size shown in Table 1 was added to
The surface-modified TiCN powders a to j were prepared by performing the surface modification treatment under the conditions shown in FIG.

Next, the surface-modified TiCN powders a to j, each having a predetermined average particle diameter within the range of 0.5 to 3 μm, and various metal carbon / nitride powders shown in Table 2, Using Co powder and Ni powder as raw material powder,
These raw material powders were similarly compounded into the compounding compositions shown in Tables 2 and 3, wet mixed in a ball mill for 72 hours, dried, and then press-molded into a cutting chip shape of SNMG432,
The resulting green compact is heated to 10 ^-2 from room temperature to 1100 ° C.
The temperature is raised in a nitrogen atmosphere of torr, the temperature is raised to the subsequent sintering temperature, and the temperature is maintained at a predetermined sintering temperature within the range of 1420 to 1500 ° C. for 1 hour, and further cooling from the sintering temperature to room temperature is 10 torr Inventive T
iCN-based cermet (hereinafter referred to as cermet of the present invention)
1 to 10 and conventional TiCN-based cermets (hereinafter, conventional cermets) 1 to 10 were manufactured.

The conventional cermets 1 to 10 are all manufactured under the same conditions except that TiCN powder which is not surface-modified is used as the raw material powder. 1 and 2, the cermet 7 of the present invention is shown.
Also, a structure photograph of the conventional cermet 7 by a scanning electron microscope (4000 times) is shown.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

[0015]

[Table 4]

Next, for each of the various cermets obtained as a result, the ratio of TiCN grains having an aspect ratio of 1.4 or less to the entire TiCN grains was determined by image processing based on the microstructure photograph, and the toughness was further evaluated. The fracture toughness value was measured for the purpose of Also, by using these various cermets as cutting tools, the work material: JIS / SNCM439 (hardness: H _B 270)
Square bar, cutting speed: 160 m / min., Depth of cut: 3 mm, feed: 0.5 mm / rev., Cutting time: 5 minutes, a dry high-speed intermittent cutting test of steel was performed, and the flank wear width of the cutting edge Was measured. The results are shown in Table 4.
In addition, Table 4 also shows the shape of the TiCN grains constituting the hard dispersed phase.

[0017]

From the results shown in Tables 1 to 4 and FIGS. 1 and 2, all of the cermets 1 to 10 of the present invention have the TiCN grains forming the hard dispersed phase rounded and spheroidized. 50 TiCN grains with an aspect ratio of 4 or less
It occupies more than area%, and as a result, it has excellent toughness, so even if it is used for high-speed intermittent cutting of steel that requires high toughness, chipping and chipping of the cutting edge do not occur,
While exhibiting excellent wear resistance over a long period of time,
All of the conventional cermets 1 to 10 have a shape in which the TiCN grains are angular, and the proportion of relatively elongated TiCN grains is high, resulting in poor toughness.
Therefore, when this is used for high-speed intermittent cutting of steel, chipping occurs in the cutting edge due to insufficient toughness, and it is clear that the service life is reached in a relatively short time. As mentioned above,
The TiCN-based cermet of the present invention has excellent toughness, so when used as a cutting tool or various wear resistant tools used under severe conditions requiring high toughness, it exhibits excellent performance for a very long time. To do.

[Brief description of drawings]

FIG. 1 is a structural photograph of a cermet 7 of the present invention by a scanning electron microscope (magnification: 4000 times).

FIG. 2 is a structural photograph (magnification: 4000 times) of a conventional cermet 7 by a scanning electron microscope.

Claims (1)

[Claims] 1. One or two kinds of Co and Ni as a binder phase forming component: 5 to 30% by weight, and a carbide of Ta, Nb, Zr, W, and Mo as a hard phase forming component, and A nitride, and one or more of these two or more solid solutions: 5 to 30%, similarly, a titanium carbide / nitride as the hard phase forming component: the rest, and a sintered body having a compounding composition of Spheroidized carbon having titanium carbonitride grains forming the hard dispersed phase of the sintered body rounded and having an aspect ratio (long axis / minor axis) of 50 area% or more of the titanium carbonitride grains of 1.4 or less. A titanium carbonitride-based cermet having excellent toughness, characterized by having a structure composed of titanium nitride grains.