JPS63216941A - High-toughness cermet for cutting tool - Google Patents

Abstract

PURPOSE:To develop a cermet for cutting tools excellent in toughness and wear resistance, by sintering a green compact which consists of a core part and a ring part composed of complex carbonitrides of specific metals, respectively, and in which Ni or Co is used as binder. CONSTITUTION:A green compact of powder mixture in which a mixture of a powder of complex carbonitride of Ta and/or Nb and Ti and a powder of Ni or Co as a binding-phase component at the time of sintering is used as a core material and a mixture of a powder of complex carbonitride of Ta and/or Nb, W and/or Mo, and Ti and a powder of Ni or Co as a binding-phase component is used as a ring material outside the above core material and which has a composition consisting of 80-95%, in total, of complex carbonitrides and the balance binder such as Ni, Co, etc., is sintered at high temp. In the above material, Ni and Co are used as binding-phase materials and complex carbonitrides are used as hard dispersed phases, respectively. By this method, the metal carbonitride cermet for cutting tools having large cutting capacity and also excellent in toughness and wear resistance can be developed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention has excellent toughness and wear resistance, and can be used as a cutting tool not only for continuous cutting of steel, but especially for interrupted cutting. This relates to a cermet that exhibits excellent cutting performance when

[Conventional technology]

Conventionally, cermets for cutting tools have been made of capacitance chi (hereinafter referred to as capacitance Chi), Ti, one or two of %Ta and Nb (hereinafter referred to as Ta/Nb), W and Mo. Composite metal carbonitride of one type or 2af (hereinafter referred to as W/Mo) [hereinafter referred to as (Ti, Ta/Nb, W/Mo) CN
A hard dispersed phase consisting of: 80 to 95%, the remainder being N as a binder phase forming component and c
A cermet has been proposed that has a composition consisting of one flf or two (hereinafter referred to as Ni/Co) of o (hereinafter referred to as Ni/Co) and unavoidable impurities, and a double structure in which the composite metal carbonitride has a core and a ring. There is.

[Problem that the invention seeks to solve]

However, although the above-mentioned conventional cermets have excellent wear resistance, when they are used, for example, for interrupted cutting of steel, the cutting edge tends to break due to lack of toughness, making it difficult to put them into practical use. The current situation is that this is not possible.

[Means for solving problems]

Therefore, the present inventors focused on the above-mentioned conventional cermet, and conducted research to add excellent toughness to it without impairing its excellent wear resistance. As a result, (a) hardness of cermet In the case of the above-mentioned conventional cermet, the dispersed phase is TiCN powder, TiN
Since we use powder, TaC powder, NbC powder, WC powder, Mo2C powder, Ni powder, and COC powder,
During sintering, a part of TiCN is added to the liquid phase of Ni/Co.
and TiN%TaC%NbC, WC, and Mo2C
is dissolved, and during the cooling process, TiCN, TiN, then WC and Mo2C, and finally TaC and NbC are precipitated on the chest circumference of the undissolved TiCN grains. Therefore, in the double structure structure of the hard dispersed phase in the conventional cermet, the core part is made of TiCN and the ring part is made of ((Ti, T
a, /Nb.

W/Mo) Must be composed of CN.

(b) The reason why conventional cermets composed of such a hard dispersed phase with a double structure structure is inferior in toughness is due to the core portion that constitutes the double structure.

(C) As raw material powders, %Ti and Ta/Nb were used instead of TiCN powder, TiN powder, TaC powder, and Ni)C powder, which were conventionally used in the production of cermets.
When carbonitride [hereinafter referred to as (Ti, Ta/Nb) CN] powder is used, the manufactured cermet has a core composed of (Ti゜Ta/Nb)CN and a ring part composed of (((Ti゜Ta/Nb)CN) powder. Ti, Ta/Nb.

A hard dispersed phase with a dual structure composed of W/Mo) CH) is formed, and the resulting cermet has extremely high toughness and excellent wear resistance. .

The findings shown in (a) to (C) above were obtained.

This invention was made based on the above findings, and includes [(Ti, Ta/Nb.

W/Mo) Composite metal carbonitride sea urchin consisting of CN 80~
95%.

and the remainder is Ni/C as a binder phase forming component.
.

and unavoidable impurities, and the composite metal carbonitride has a double structure structure of a core part and a ring part, and the core part is composed of (Ti, Ta/Nb)CN, and the ring The part is (Ti, Ta/Nb,
This is a cermet for cutting tools that is composed of W/Mo) CN and has high toughness and excellent wear resistance.

In the cermet of the present invention, if the content of composite metal carbonitride is less than 80%, the desired excellent wear resistance cannot be ensured, while if the content exceeds 95%, the relatively Since the content of the binder phase-forming component is too low and the desired high toughness cannot be secured regardless of the hard dispersed phase structure, the content of the composite metal carbonitride is set at 80 to 95%. Ta.

〔Example〕

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

Various powders having the composition shown in Table 1 and a predetermined average particle size within the range of 0.8 to 1.5 μm are prepared as raw material powders, and these raw material powders are
Mix according to the composition shown in the table and mix under normal conditions,
By press-forming into a compact and sintering, the content of composite metal carbonitride as a hard dispersed phase forming component and Ni/Co as a binder phase forming component is substantially the same as the blended composition, and The core is (Ti, Ta/Nb) CN
The ring part is (Ti, Ta/Nb, W
/Mo) Cermets 1 to 1 of the present invention in which a hard dispersed phase is formed of a composite metal carbonitride with a double structure composed of ON.
8, and the cermet of the present invention 1 except that the core of the composite metal carbonitride constituting the hard dispersed phase is composed of TiCN.
Comparative cermets 1 to 8, which were the same but corresponding to conditions corresponding to cermets 1 to 8, respectively, were produced. Note that the core and ring portions of the composite metal carbonitride in the cermet were observed by X-ray diffraction and EPMA (electron probe microanalyzer).

Next, the various cermets obtained as a result were used as a cutting tool, and a workpiece material: a round bar of SN0M439 (hardness: HB260).

Cutting speed: 160m/mute, Feed: 0.3 mx / rev, depth of cut = 2B.

Cutting time: 3nia.

Continuous cutting test of steel under the conditions of and work material: SN
CM 439 (hardness: HB280) square material, cutting speed:
l 40m 7nia.

Feed: 0.26 rtux/rev, depth of cut = 2
H1 Cutting time: 3 hours, An interrupted cutting test was conducted on steel under the following conditions. In the continuous cutting test, the flank wear width and rake face wear depth of the cutting edge were measured, and in the interrupted cutting test, the number of test cutting edges was 2. The number of defects among the 10 pieces was measured. The results of these measurements are shown in Table 1.

〔Effect of the invention〕

From the results shown in Table 1, cermets 1 to 8 of the present invention have excellent wear resistance equivalent to comparative cermets 1 to 8, in which the core of the composite metal carbonitride constituting the hard dispersed phase is made of TiCN. It is clear that the toughness is much better than this, and the occurrence of defects on the cutting edge is significantly lower.

As mentioned above, the cermet of the present invention has excellent wear resistance and particularly excellent toughness, so when it is used as a cutting tool, it can be used not only in continuous cutting, but especially in interrupted cutting. There is no occurrence of this, and excellent cutting performance can be achieved over a long period of time.

Claims (1)

[Scope of Claims] A composite metal carbonitride of Ti, one or two of Ta and Nb, and one or two of W and Mo as hard dispersed phase forming components: 80 to 95 % by volume, with the remainder being Ni and C as binder phase forming components.
o and unavoidable impurities, and the composite metal carbonitride has a double structure structure consisting of a core and a ring, and the core has Ti and T.
The ring portion is composed of one or two composite metal carbonitrides of a and Nb, and the ring portion is made of Ti, one or two of Ta and Nb, and one of W and Mo. Or a high-toughness cermet for cutting tools, characterized by being composed of two types of composite metal carbonitrides.