JPH091405A - Cutting tool made of ti-w system carbonitride group cermet excellent in defectiveness resistance - Google Patents

Abstract

PURPOSE: To provide a cermet-made cutting tool excellent in defectiveness resistance. CONSTITUTION: A cermet-made cutting tool contains a binding phase of 5-25 capacity % having the main component of Co and/or Ni, the remainder is composed of a hard phase and an inevitable impurity, and 80 capacity % of the hard phase has core structure organization; and also, a core part, for constituting the core structure organization, is constituted of (Ti, W) CN and/or (Ti, W, M) CN, and a peripheral part is constituted of (Ti, W, M) CN. Moreover, 50 capacity % or more out of the hard phase, having the core structure organization, is constituted of cermet (provided that, M is one kind or more out of Nb, Ta, V, Mo, Zr, and Cr) where the side of a core part has concentration distribution, wherein the content of Ti and W is high, compared with a peripheral part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention shows excellent chipping resistance not only for continuous cutting but also for intermittent cutting at high speeds, and has excellent cutting performance without chipping or chipping of the cutting edge. The present invention relates to a Ti-W-based carbonitride-based cermet cutting tool (hereinafter simply referred to as a cermet cutting tool) that is effective over a long period of time.

[0002]

2. Description of the Related Art Conventionally, cermet cutting tools have been used for continuous cutting and intermittent cutting of steel and the like. Further, the above cermet cutting tool can be used as a raw material powder at least T as described in, for example, JP-A-64-68443.
Composite carbonitride of i and W (hereinafter referred to as (Ti, W) CN) powder and / or Ti, W and M (M is Nb, T
one or two of a, V, Mo, Zr, and Cr
Compound carbonitrides (denoted by (Ti, W,
M) powder, designated CN, and Co and / or Ni
The powder is compounded and mixed under normal conditions, and then pressed into a green compact, and the green compact is vacuumed or in a nitrogen atmosphere at a predetermined temperature within a range of 1400 to 1600 ° C. for a predetermined time. It is also known to be manufactured by sintering under the condition of holding. Furthermore, the conventional cermet cutting tool has a binder phase containing Co and / or Ni as a main component:
5 to 25% by volume, the rest consisting of a hard phase and unavoidable impurities, and 80% by volume or more of the hard phase has a core structure structure, and the core portion constituting the core structure structure is (Ti , W) CN and / or (Ti, W, M) C
It is also known that it is made of N and its peripheral portion is made of a Ti—W carbonitride-based cermet (hereinafter, simply referred to as cermet) made of (Ti, W, M) CN.

[0003]

On the other hand, in recent years, there has been a strong demand for labor saving and energy saving in the cutting work, and accordingly, the cutting work tends to be speeded up. However, in the above cermet cutting tool, In particular, when intermittent cutting is performed at high speed using this, chipping or chipping (fine chipping) is likely to occur on the cutting edge due to lack of fracture resistance, leading to a relatively short service life. The current situation.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoints, focusing on the above-mentioned conventional cermet cutting tool, as a result of conducting research to improve the fracture resistance of the cutting tool, the sintering conditions adopted in the production of the above-mentioned conventional cermet cutting tool The vacuum atmosphere or nitrogen atmosphere, which is the sintering atmosphere, is a carburizing atmosphere, for example, a vacuum of 0.1 torr or less from 1150 to 1350 ° C. in the temperature rising process, and thereafter, CH _{4 in} a hydrogen gas flow as a carrier gas. Alternatively, when the carburizing atmosphere is introduced by introducing CO at a partial pressure of 0.1 to 0.5 torr, in the above conventional cermet cutting tool, a hard phase having a core structure structure in the cermet constituting the cutting tool. Concerning the concentration distributions of Ti and W in the core portion and the peripheral portion, the content of Ti and W in the peripheral portion is higher than that in the core portion, or the content of Ti in the core portion is higher than that in the peripheral portion. When it is high, the W content is higher in the peripheral portion, or conversely, when the W content is higher in the core portion, the Ti content is higher in the peripheral portion than in the core portion.
What had a concentration distribution of i and W, the content of Ti and W was 50% by volume or more of the hard phase having the above-mentioned core structure by the carburizing atmosphere sintering. In addition, the core has a higher concentration distribution than the peripheral part, and the cermet cutting tool composed of the cermet in this state has extremely excellent fracture resistance and can perform intermittent cutting at high speed. The research results show that even if the cutting is performed, the cutting edge does not chip or chip, and excellent cutting performance is exhibited.

The present invention was made based on the above-mentioned research results, and contains a binder phase containing Co and / or Ni as a main component: 5 to 25% by volume, and the rest containing a hard phase and unavoidable impurities. And 80% by volume or more of the hard phase has a core structure structure, and the core part constituting the core structure structure is (Ti, W) CN and / or (Ti, W, M) CN. And the surrounding area is (Ti,
In a cutting tool composed of a cermet made of W, M) CN, 5 out of the hard phases having the core structure structure
A content of 0% by volume or more is characteristic of a cutting tool made of cermet having excellent fracture resistance, in which the core has a concentration distribution in which the content of Ti and W is higher than that of the peripheral portion.

In the cermet cutting tool of the present invention, the content ratio of the binder phase is set to 5 to 25% by volume because if the content ratio is less than 5% by volume, sufficient sinterability cannot be obtained. This result is because the strength is decreased, and when the content ratio exceeds 25% by volume, the hardness is decreased and the wear resistance is rapidly decreased, and the core has a core structure structure. The content ratio of the hard phase is set to 80% by volume or more in the ratio of the hard phase. When the content ratio is less than 80% by volume, the content ratio of the single phase hard phase becomes higher than 20% by volume. As such, when the relative amount of the single-phase hard phase is relatively large, this is because, in combination with the low adhesion to the binder phase of the single-phase hard phase, the progress of wear is rapidly accelerated, In addition, the core is more Ti than the peripheral And the content ratio of the hard phase in the cored structure tissue having a high density distribution content W, and a 50 volume% or more as a percentage of the hard phase of the cored structure organization,
This is because if the content ratio is less than 50% by volume, the desired excellent fracture resistance cannot be secured as described above.
Further, the content ratio of the hard phase having the above core structure can be adjusted by the sintering temperature, the higher the sintering temperature,
The content ratio is higher, and the content ratio of the hard phase in the core structure structure having a concentration distribution in which the content of Ti and W is higher in the core portion is the content of the carburizing component in the sintering atmosphere. It can be adjusted by pressure, and the higher the partial pressure, the higher the content ratio.

[0007]

EXAMPLES As raw material powders, (Ti _0.7 W _0.3 ) CN powder, (Ti _0.7 W _0.3 ), each having an average particle size of 1.5 μm or less,
_0.7 W _0.2 M _0.1 ) CN powder, (Ti _0.6 W _0.2 Ta
_0.1 V _0.1 ) CN powder, (Ti _0.7 Ta _0.3 ) CN powder, (Ti _0.6 Zr _0.3 V _0.1 ) CN powder, (V _0.6 N
b _0.4 ) CN powder, (Ti _0.8 V _0.1 Nb _0.1 ) CN powder, TiC powder, TiN powder, TiCN powder, ZrC powder, TaC powder, NbC powder, VC powder, Cr ₃ C ₂ powder, Mo ₂ C powder, WC Powder, Co powder, and Ni powder were prepared, and these raw material powders were blended to the blending composition shown in Table 1, and were mixed in a methanol solvent using a ball mill for 24 hours.
After mixing for a time and drying, CN at a pressure of 1 ton / cm ²
Powder compacts A to M by press molding into the shape of MG160408
And then sintering each of the green compacts A to M under a combination shown in Tables 3 and 4 under any of the sintering conditions a to f shown in Table 2. Cermet cutting tools of the present invention (hereinafter referred to as the present invention cutting tools) 1 to 13 and conventional cermet cutting tools (hereinafter referred to as the conventional cutting tool) 1 to 7 were manufactured by applying them.

Next, regarding various cutting tools obtained as a result, 10 μm × 10 μm in 5 arbitrary cross sections
Each region of the is observed using a scanning electron microscope (SEM), the content ratio of the hard phase (shown in the "total" column in Tables 3 and 4), and the hard phase of the hard phase having a core structure The content ratio (shown in the column of "core structure microstructure" in Tables 3 and 4) occupying the whole is measured, and the core portion in the hard phase having the core structure microstructure is further measured by an Auger electron spectrometer (AES). The content of Ti and W in the peripheral portion was measured, and from this result, the content of either Ti or W was higher in the core portion than in the peripheral portion, and occupied in the hard phase having the core structure structure of the hard phase. The content ratio (in Tables 3 and 4 is shown in the column of "concentration gradient of Ti and W in core is high") was calculated. These results are shown in Table 3,
4 shows the average value. For these cutting tools, the work material: four SCM440 equally spaced round bars with vertical grooves,
Cutting speed: 350m / min, feed: 0.16mm / rev.,
A dry high-speed intermittent cutting test of steel was carried out under the conditions of depth of cut: 1 mm and cutting time: 2 minutes to measure the flank wear width of the cutting edge. The results of these measurements are also shown in Tables 3 and 4.

[0009]

[Table 1]

[0010]

[Table 2]

[0011]

[Table 3]

[0012]

[Table 4]

[0013]

From the results shown in Tables 3 and 4, the cutting tools 1 to 13 of the present invention are all 80% by volume of the hard phase.
The above has a core structure structure, and 50% by volume of this
The above shows that the content of Ti and W in the core portion has a higher concentration gradient than in the peripheral portion, and as a result, it has excellent fracture resistance. Even if it is performed at high speed, the cutting edge does not chip or chip, and it exhibits excellent wear resistance.
In all of Nos. 7 to 7, although 80% by volume or more of the hard phase has a core structure structure, there is no hard phase in which the content of W and Ti is higher in the core, As a result, the chipping resistance becomes insufficient, and the cutting edge is chipped, and it is apparent that the service life is reached in a relatively short time. As described above, since the cermet cutting tool of the present invention has excellent fracture resistance, it is excellent not only in continuous cutting but also in chipping or chipping of the cutting edge even when intermittent cutting is performed at high speed. The cutting performance is demonstrated over a long period of time.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Katsuhisa Nonaka 1511 Furamaki, Ishishita-cho, Yuki-gun, Ibaraki Pref. Mitsubishi Materials Corporation Tsukuba Works

Claims (1)

[Claims] 1. A binder phase containing Co and / or Ni as a main component: 5 to 25% by volume, the rest consisting of a hard phase and inevitable impurities, and 80% by volume or more of the hard phase having a core structure. A composite carbonitride having a structure and having a core portion constituting the core structure structure of Ti and W and / or Ti
And W and M composite carbonitride, with Ti and W in the periphery
And M composite carbonitride (where M is Nb, Ta,
V, Mo, Zr, and one or more selected from Cr), which is a cutting tool composed of a Ti-W carbonitride-based cermet consisting of a hard phase having the above core structure. Of 50% by volume or more has a concentration distribution in which the content of Ti and W is higher in the core portion than in the peripheral portion. Cermet cutting tool.