JPH10298694A - Cutting tool made of cermet, excellent in wear resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the service life of a cutting tool made of cermet at the time of use for high speed cutting, by constituting the cermet so that a solid solution of compound metal carbonitride having a Ti proportion in a specific range comprises a specific percentage of the whole solid solution of compound metal carbonitride. SOLUTION: The titanium carbonitride type cermet has a composition consisting of 2-20 wt.% of Co and/or Ni as binding-phase-forming component and the balance essentially Ti and one or more elements (represented by M) among Zr, Ta, Nb, V, W, and Mo as dispersed-phase-forming components. Further, the amount of a solid solution of compound metal carbonitride having 80-95 wt.% titanium proportion is regulated so that it comprises 40 80 area% of the whole solid solution of compound metal carbonitride, where the titanium proportion is represented by Ti/(Ti+M)×100%. A CN powder having 80-95 wt.% titanium proportion is press-compacted, and the resultant green compact is heated at sintering temp. and sintered, by which the cutting tool made of cerment is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cermet cutting tool having excellent wear resistance and exhibiting excellent cutting performance over a long period of time.

[0002]

2. Description of the Related Art Conventionally, as a cutting tool made of cermet, for example, as described in Japanese Patent Application Laid-Open No. 54-67334, Co and / or N
i: 2 to 20% by weight, with the balance substantially consisting of Ti as a dispersed phase forming component and one or more of Zr, Ta, Nb, V, W, and Mo (hereinafter referred to as M ) And a composite metal carbonitride solid solution [hereinafter, (Ti, M)
A cermet based on titanium carbonitride (hereinafter referred to as TiCN) is known.
In addition, the above-mentioned conventional cermet cutting tool is basically used as a raw material powder for TiCN powder or titanium nitride (hereinafter referred to as T
iN, hereinafter also indicated by an element symbol) powder, TaN
A powder compact made of a powder, a metal carbide powder such as a WC powder, a Mo ₂ C powder, a TaC powder, an element powder such as a Co powder and a Ni powder, and compounding these raw material powders into a predetermined composition and press molding. The body was subjected to the following conditions: (a) from room temperature to 1300 ° C. for 0.1 torr.
In the following vacuum, the temperature was raised at a rate of 1 to 2 ° C./min.
When the temperature is raised to 300 ° C., the atmosphere is changed to 50 to 100 torr.
r, the temperature was raised to a sintering temperature of 1500 to 1600 ° C. at a rate of 1 to 2 ° C./min in place of the nitrogen atmosphere of (r). (c) After maintaining the same sintering temperature in the same atmosphere for 1 to 2 hours, (d) It is also known that it is manufactured by furnace cooling to room temperature in a vacuum atmosphere of 0.1 torr or less and sintering under the above conditions (a) to (d). Furthermore, it is also known that the above-mentioned conventional cermet cutting tool is used for continuous cutting or intermittent cutting of, for example, steel or cast iron.

[0003]

On the other hand, in recent years, the performance of cutting devices has been remarkably improved, and there has been a strong demand for labor-saving cutting processes. Accordingly, cutting processes have tended to be accelerated. In conventional cermet cutting tools,
When this is used for high-speed cutting, the wear progress of the cutting edge becomes remarkably fast, and the service life is currently reached in a relatively short time.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoints, as a result of researching to develop a cermet cutting tool having excellent wear resistance, (A) a secondary electron image of a cross section of the above-mentioned conventional cermet cutting tool was taken with a scanning electron microscope. When the structure is observed, (Ti, M) CN that forms the dispersed phase includes those showing a black color tone and those showing a gray-white color tone, and can be classified into two types in terms of color tone. (B) When (Ti, M) CN of (A) is spot-analyzed by an X-ray microanalyzer, (Ti, M) CN showing a black color tone is expressed by a weight ratio of Ti / (Ti + M) ×
100 (%) = 80% or more, while (Ti, M) CN showing an off-white color tone is also Ti / (Ti + M) ×
100 (%) = less than 80%. (C) In the conventional cermet cutting tool described above, the color tone is black, that is, Ti / (Ti + M) × 1 when the structure of the tool cross section is observed by a scanning electron microscope (secondary electron image).
(Ti, M) CN having 80% by weight or more (hereinafter referred to as Ti ratio) accounts for less than 20 area% in (Ti, M) CN and has a grayish white color, ie, T
(Ti, M) CN having an i ratio of less than 80% by weight
Occupy 0% or more. (D) When producing a cutting tool made of cermet, as a raw material powder for forming a dispersed phase, the Ti ratio is basically 80 to 95.
% Of (Ti, M) CN powder and the (T
i, M) The following conditions were applied to a green compact formed by mixing and pressing a CN powder at a predetermined ratio and pressing.
(A) The temperature is raised from room temperature to 1300 ° C. in a vacuum of 0.1 torr or less at a rate of 10 to 20 ° C./min.
When the temperature is raised to 00 ° C., the atmosphere is
rr of hydrogen (H ₂ ) as a main component, and a mixture of a predetermined amount of nitrogen (N ₂ ) and methane (CH ₄ ) in a mixed gas atmosphere to a sintering temperature of 1400 to 1450 ° C.
(C) After maintaining the same sintering temperature in the same atmosphere for 5 to 20 minutes, (d) gas quenching with Ar or the like, and the above conditions (a) to (d) Sintering at a low temperature for a short period of time, and the Ti
The composition of the (Ti, M) CN powder having a ratio of 80 to 95% by weight should be as small as possible during sintering, and after sintering, the ratio of this to (Ti, M) CN should be 40 to 8%.
If they are present at a ratio of 0 area% (therefore,
As a result, the (Ti, M) CN having a Ti ratio of less than 80% by weight, desirably a Ti ratio of 5 to less than 80% by weight has the remaining 2%.
0 to 60% by area), and the resulting cermet-made cutting tool composed of the TiCN-based cermet exhibits excellent wear resistance and excellent cutting performance over a long period even at high speed cutting. To demonstrate. (A)
To (D).

The present invention has been made on the basis of the above-mentioned research results, and contains 2 to 20% by weight of Co and / or Ni as a binder phase-forming component, with the balance being substantially a dispersed phase-forming component. (Ti, M) CN as
M is one of Zr, Ta, Nb, V, W, and Mo
Of a cermet cutting tool composed of a TiCN-based cermet consisting of two or more species), the structure of the TiCN-based cermet is measured by measuring a micrograph (secondary electron image) of the tool cross section with a scanning electron microscope. Do (T
(Ti, M) C shows the proportion occupying 40-80 area% of (i, M) CN and the proportion of Ti is 80-95 wt%.
The present invention is characterized in that the cutting tool is made of N and has excellent wear resistance.

It is to be noted that the TiCN-based cermet constituting the cermet cutting tool of the present invention is a component (T
As described above, among (i, M) CN, (Ti, M) CN having a Ti ratio of 80 to 95% by weight shows black in a structure photograph (secondary electron image) by a scanning electron microscope. The reason for setting this ratio to 40 to 80 area% is that when the ratio is less than 40 area%, the Ti ratio becomes 80 as described above.
Wt%, desirably less than 5 to 80 wt% (Ti,
Since the ratio of (M) CN becomes substantially more than 60% by area and this (Ti, M) CN is softer than (Ti, M) CN having a Ti ratio of 80 to 95% by weight, When the hardness of the tool itself is low and the desired excellent wear resistance cannot be ensured for the tool, while the proportion exceeds 80 area%, the above-mentioned Ti proportion is 80 to 95% by weight of (Ti,
M) The ratio of CN is less than 20 area%, the toughness of the tool is reduced, and the cutting edge is chipped or chipped (small chipping).
Are more likely to occur, and the Ti ratio in the (Ti, M) CN is 80 to 95.
When the proportion is less than 80% by weight, the hardness of (Ti, M) CN itself sharply decreases, and the desired excellent wear resistance of the tool cannot be secured. When the proportion exceeds 95% by weight, on the contrary, (Ti, M) C
The hardness of N itself becomes too high, the toughness of the tool decreases,
This is based on the reason that chipping or chipping (small chipping) is likely to occur in the cutting blade.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Having a predetermined average particle size in the range of ２2 μm (Ti,
W, Mo) CN [by weight (the same applies hereinafter), Ti / W / M
o = 90/5/5, C / N = 50/50 (C / N is the same in (Ti, M) CN shown below, so the display is omitted) Powder, (Ti, Ta, V) CN [Ti / Ta /
V = 95/2/3] powder, (Ti, Zr, Cr) CN
[Ti / Zr / Cr = 90/5/5] powder, (Ti, T
a, Mo) CN [Ti / Ta / Mo = 85/10/5]
Powder, (Ti, W) CN [Ti / W = 95/5] powder,
(Ti, Zr) CN [Ti / Zr = 80/20] powder,
TiCN powder, TiN powder, WC powder, Mo ₂ C powder,
TaC powder, ZrC powder, Cr ₃ C ₂ powder, VC powder,
NbC powder, Co powder, and Ni powder were prepared, and these raw material powders were blended in the blending composition shown in Table 1, wet-mixed in a ball mill for 72 hours, dried, and then dried.
0408 is pressed into a green compact in the form of a throw-away tip, and this green compact is (a)
Up to 150 ° C. in a vacuum of 0.1 torr at a rate of 15 ° C./min, and (b) when the temperature is raised to 1300 ° C., the atmosphere is
150 torr mixed gas atmosphere (H ₂ : N ₂ : CH ₄
= 65: 30: 5 in volume ratio), and the temperature was increased at a rate of 15 ° C / min to a sintering temperature of 1400 ° C. (C) After maintaining the same sintering temperature in the same atmosphere for 10 minutes, (d) ) Sintering under the condition of gas quenching by Ar gas flow
The cermet cutting tools of the present invention (hereinafter, referred to as the present cutting tools) 1 to 13 were manufactured by performing round honing of m.

For comparison purposes, TiCN powder, TiN powder, WC powder, Mo ₂ C powder, TaC powder, ZrC powder, Cr ₃ C ₂ powder, VC powder, NbC powder, Powder, elemental powder composed of Ni powder, and TaN powder were used, and these raw material powders were blended so that the proportions of the binder phase and the dispersed phase were the same as those of the cutting tools 1 to 13 of the present invention as shown in Table 2. The sintering conditions were as follows: (a) From room temperature to 1300 ° C., 0.1 t
heating at a rate of 1.5 ° C./min in a vacuum of orr, (b)
When the temperature was raised to 1300 ° C, the atmosphere was changed to a nitrogen atmosphere of 100 torr and the sintering temperature of 1550 ° C was 1.5 ° C.
(C) After maintaining the same sintering temperature in the same atmosphere for 1.5 hours, (d) the atmosphere is set to 0.1 torr.
r Furnace cooling to room temperature as vacuum atmosphere, above (a)-
Conventional cermet cutting tools (hereinafter referred to as conventional cutting tools) 1 to 13 were manufactured under the same conditions except for the condition (d).

The resulting cutting tools 1 to 13 of the present invention
In addition, with respect to the conventional cutting tools 1 to 13, an arbitrary 1 at a depth position of 50 μm from the burnt skin surface in an arbitrary polished cross section
Using a scanning electron microscope, each of the 0 tissues was
Observed at a magnification of 000, and based on the resulting micrograph (secondary electron image), the ratio of black (Ti, M) CN and blackish-white (Ti, M) CN was determined by an image analyzer. It measured using. The measurement results are shown in Table 3 as an average value at 10 locations. In addition, (Ti, M) CN with a black tone and (Ti,
M) CN was spot-analyzed by an X-ray microanalyzer for 10 samples each, and (Ti, M) CN having a black color tone had a Ti ratio of 80 to 95 in all cases.
(Ti, M) CN whose color tone is gray-white
Indicates that the Ti ratio is less than 80% by weight.

Further, regarding the above-mentioned cutting tools 1 to 13 of the present invention and conventional cutting tools 1 to 13, a work material: a round bar of JIS S45C, a cutting speed: 400 m / min, a feed: 0.2 mm / rev, a cutting depth : 1 mm, cutting time: 5 minutes, a dry high-speed continuous cutting test of carbon steel was performed, and the flank wear width of the cutting edge was measured. Table 3 shows the results of these measurements.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

According to the results shown in Table 3, the Ti ratio was 8%.
0-95% by weight of (Ti, M) CN is 40-80% by area
All of the cutting tools 1 to 13 of the present invention exhibit excellent wear resistance in high-speed cutting of steel, whereas (Ti, M) CN having a Ti ratio of less than 80% by weight has an area of 80% by area or more. It is clear that all of the conventional cutting tools 1 to 13 occupy wear rapidly, and that shortening of service life is inevitable. As described above, the cermet cutting tool of the present invention exhibits excellent wear resistance over a long period of time, not only under normal conditions but also under high-speed cutting under severe conditions. It has industrially useful characteristics such as being able to sufficiently satisfy high performance and labor saving in cutting.

 ────────────────────────────────────────────────── ─── 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-forming component containing Co and / or Ni: 2 to 20% by weight, the balance being substantially Ti as a dispersed phase-forming component, and Zr, Ta, Nb, V,
One or more of W and Mo (hereinafter M
Cermet cutting tool composed of a titanium carbonitride-based cermet consisting of a composite metal carbonitride solid solution with a microstructure (secondary electron image) of a tool cross section measured by a scanning electron microscope. 40 to 80 area% of the composite metal carbonitride solid solution constituting the titanium carbonitride cermet
Is occupied by Ti / (Ti + M) × 100 (%) =
A cermet cutting tool having excellent wear resistance, comprising a composite metal carbonitride solid solution satisfying 80 to 95% by weight.