JPH10110234A - Cutting tool mode of carbo-nitrided titanium cermet excellent in chipping resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool made of carbon-nitrided titanium cermet excellent in chipping resistance. SOLUTION: This cutting tool made of carbon-nitrided titanium cermet is the one having a compsn. contg. 3 to 20wt.% bonding phases essentially consisting of Co and/or Ni, and the balance hard phases with a two phase structure composed of core parts composed of carbo-nitrided titanium or carbo- nitride of Ti and one or more kinds among the group 4a, 5a and 6a metals excluding Ti (hereinafter, they are generally denoted by M) and surface parts completely surrounding and distributing around the core parts with inevitable impurities. In this case, a part (by >=30 area % in the measurement by an electron microstructure at the inside of the tool) or the whole body of the two phase structural hard phases is composed of two phase structural hard phases with a structure in which, though the compsn. and componental concn. gradient in the core parts and surface parts are same, a part of the core parts exposes to the bonding phases, and the surface parts are discontinuously distributed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent chipping resistance, for example, when cutting steel under heavy cutting conditions such as high depth of cut or high feed, and when performing intermittent cutting, chipping or chipping of the cutting edge. The present invention relates to a titanium carbonitride-based cermet cutting tool (hereinafter, simply referred to as a cermet tool) which exhibits excellent cutting performance for a long period of time without occurrence of the above.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3 which is described in, for example, Japanese Patent Publication No. 56-51201, and further shows a schematic view of the internal structure of a tool by an electron microscope as shown in FIG.
Coupling phase mainly composed of Co and / or Ni 1: 3 to 2
0% by weight, the balance being Ti and a carbonitride with one or more of the metals of groups 4a, 5a and 6a of the periodic table excluding Ti (hereinafter collectively referred to as M) [Less than,
(Ti, M) CN], and / or titanium carbonitride (hereinafter, referred to as TiCN);
(Ti, M) CN, which has a component concentration gradient with a lower Ti concentration and a higher M concentration than the core portion, and a surface portion 2b which is completely surrounded and distributed with respect to the core portion. There is known a cermet tool having a composition comprising a hard phase 2 having a two-phase structure and unavoidable impurities.

[0003]

On the other hand, the recent trend toward FA and high performance of cutting equipment is remarkable, and there is a strong demand for labor saving and energy saving of cutting work.
There is a tendency for cutting tools that can be used not only for continuous cutting, but also for intermittent cutting, and that can also perform heavy cutting such as high feed and high depth of cut. When intermittent cutting is used for cutting under heavy cutting conditions such as high feed and high depth of cut, chipping or chipping (small chipping) is likely to occur on the cutting edge due to chipping resistance. At present, the service life is reached.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoints, the above-mentioned conventional cermet tools were focused on, and research was carried out to improve the fracture resistance thereof. As a result, the sintering of the conventional cermet tools is usually performed by: Heating rate: 1 to 3 ° C / min. (B) Atmosphere of temperature rise from room temperature to 1200 to 1350 ° C:
A vacuum atmosphere of 0.1 torr or less, (c) a sintering temperature of 1200 to 1350 ° C.
Temperature rising atmosphere to 0 to 1560 ° C: 0.5 to 30 torr
(D) Holding time and atmosphere at the above sintering temperature: 60 to 9
0 minutes and a nitrogen atmosphere of 0.5 to 30 torr, (e) Cooling: furnace cooling in a vacuum atmosphere of 0.1 torr or less, which is carried out under the above conditions (a) to (e). sintering temperature in d) 138
When sintering is performed under the same conditions except that the temperature is set to 0 to 1460 ° C., as shown in FIGS. The phase 2 has a structure in which the core 2a is exposed to the binder phase 1 and the surface 2b has a discontinuous distribution. The ratio of the two-phase structure hard phase having this structure is determined by the pressure of the sintering temperature holding atmosphere. If the sintering temperature is controlled to 30% by area or more while controlling the sintering temperature, the resulting cermet tool exhibits excellent fracture resistance,
In addition, carbides, nitrides, and carbonitrides of metals belonging to groups 4a, 5a, and 6a of the periodic table, and solid solutions of two or more of these metals (hereinafter, collectively referred to as "metal carbon / nitride")
Hard phase 3 having a single phase structure comprising at least one of
Is contained at a ratio of 3 to 30% by weight, the wear resistance is further improved, and as a result, even if the intermittent cutting is performed under heavy cutting conditions, chipping or chipping does not occur on the cutting edge, and the cutting is performed for a long time. The research results show that it exhibits excellent wear resistance.

The present invention has been made on the basis of the above-mentioned research results. (A) A binder phase mainly composed of Co and / or Ni: 3 to 20% by weight, and if necessary, Hard phase having a single-phase structure composed of at least one of carbon and nitride: 3 to 30% by weight, and the remainder is (T
a core made of (i, M) CN and / or TiCN, and a core made of (Ti, M) CN.
a cermet having a composition comprising a hard phase having a two-phase structure having a component concentration gradient having a low i concentration and a high M concentration, and a surface portion completely surrounding and distributed with respect to the core, and unavoidable impurities; In the tool, one part of the above-mentioned two-phase structure hard phase (however, 3
0% by area or more) or two phases having a structure in which the core and the surface have the same composition and component concentration gradient, but a part of the core is exposed to the binder phase and the surface is discontinuously distributed. The present invention is characterized by a cermet tool having excellent fracture resistance and composed of a structural hard phase.

In the cermet tool of the present invention, the ratio of the binder phase is set to 3 to 20% by weight. If the content is less than 3% by weight, the sinterability is reduced and a predetermined strength is secured. On the other hand, if the content exceeds 20% by weight, the abrasion resistance rapidly decreases, and the metal carbon / nitride constituting the hard phase having the single-phase structure is hardly used. The reason for setting the ratio to 3 to 30% by weight is that
If the content is less than 3% by weight, the desired effect of improving the wear resistance cannot be obtained, while if the content exceeds 30% by weight, the chipping resistance decreases, and the discontinuity is further reduced. The reason that the ratio of the two-phase structure hard phase in the distribution surface portion is 30 area% or more is that if the ratio is less than 30 area%, a remarkable improvement effect on fracture resistance cannot be obtained.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a cermet construction according to the present invention will be described.
The components will be specifically described with reference to examples. As raw material powder,
Ti having a predetermined average particle size in the range of 0.5 to 2 μm
CN (TiC / TiN = 50/50, weight ratio, hereinafter the same)
E) powder, TiN powder, TaC powder, NbC powder, WC
Powder, Mo_Two C powder, VC powder, ZrC powder, Cr_Three C
_Two Powder, (Ti, W, Mo) CN [however, Ti / W / M
o = 70/20/10, C / N = 70/30] powder,
(Ti, Ta, V) CN [where Ti / Ta / V = 70
/ 20/10, C / N = 60/40] powder, (Ti, N
b, Mo) CN [however, Ti / Nb / Mo = 80/10
/ 10, C / N = 50/50] powder, Co powder, Ni powder
Powder and graphite (C) powder,
Each was blended to the composition shown in Table 1 and a ball mill
For 24 hours, and after drying, 1 ton / cm^Two 
Pressing into a predetermined shape with pressure of 3 to form green compacts A to M
did. Then, the green compacts A to J were sintered under the following sintering conditions.
In other words, the temperature up to 1300 ° C in the room temperature is 0.05 torr true.
2 ° C / min. At a heating rate of 13
After the temperature was raised to 00 ° C, the atmosphere was changed to a nitrogen atmosphere of 10 torr.
Instead, at the same heating rate and within the range of 1380-1460 ° C
The temperature is raised to a predetermined sintering temperature.
Atmospheric atmosphere at a predetermined pressure within the range of 0.5 to 30 torr
After adjusting, hold for 60 minutes, then continue in the same vacuum atmosphere
ISO standard by sintering under sintering condition of furnace cooling with air
The shape of the throwaway tip of CNMS120408
Cermet tools 1 to 13 of the present invention
Was. For the purpose of comparison, the green compacts A to J were also
The sintering temperature is relatively high within the range of 1530 to 1560 ° C.
Sintering under the same sintering conditions except for the specified temperature
To produce conventional cermet tools 1 to 13 respectively.
Was.

Next, for the various cermet tools obtained as a result, the surface hardness and the internal hardness were measured by Vickers hardness, and the internal structure of the tool cross section was observed with an electron microscope to determine the structure of the hard phase. The composition and the ratio were measured using an image analyzer. FIG. 1 shows the cermet tool 8 of the present invention, FIG. 2 shows the cermet tool 7 of the present invention, and FIG.
FIG. 2 is a schematic diagram showing the internal structure of a conventional cermet tool 6 observed by an electron microscope. Further, for the purpose of evaluating the fracture resistance of the various cermet tools described above, a work material: JIS S20C, a longitudinally spaced round bar with four longitudinal grooves, a cutting speed: 250 m / min. Feed: 0.2 mm / rev. Notch: 2.5 mm. Cutting time: 20 minutes, a wet high-cut intermittent cutting test of steel was performed under the following conditions, and the flank wear width of the cutting edge was measured. Tables 2 and 3 show these measurement results.
It was shown to. In the core composition column in Tables 2 and 3, A is (Ti, M) CN only, B is TiCN only, and A is
+ B indicates the presence of both (Ti, M) CN and TiCN.

[0009]

[Table 1]

[0010]

[Table 2]

[0011]

[Table 3]

[0012]

According to the results shown in Tables 2 and 3, all of the cermet tools 1 to 13 of the present invention have 30% by area or more.
The surface is composed of a two-phase hard phase with discontinuous distribution,
As a result, compared to the conventional cermet tools 1 to 13 composed of a hard phase having a two-phase structure in which the surface portion is completely surrounded by distribution or a hard phase having this hard phase and a single-phase structure, the fracture resistance is further improved. It is clear that As described above, the cermet tool of the present invention has excellent fracture resistance, so that not only continuous cutting, but also the occurrence of chipping or chipping of the cutting edge even when performing intermittent cutting under heavy cutting conditions. By exhibiting excellent cutting performance over a long period of time, it is possible to contribute to labor saving and energy saving in cutting work, and it is possible to satisfactorily cope with FA.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an internal structure of a cermet tool 8 of the present invention, as observed by an electron microscope.

FIG. 2 is a schematic diagram showing an internal structure of the cermet tool 7 of the present invention, as observed by an electron microscope.

FIG. 3 is a schematic diagram showing an internal structure of a conventional cermet tool 6 observed by an electron microscope.

Continued on the front page (72) Inventor Hisashi Tsujizaki 1511 Furamagi, Ishishita-cho, Yuki-gun, Ibaraki Prefecture Inside of Tsukuba Works, Mitsubishi Materials Corporation Tsukuba Manufacturing Co., Ltd.

Claims (2)

[Claims] 1. A binder phase mainly composed of Co and / or Ni: 3 to 20% by weight, and the remainder is composed of metals belonging to groups 4a, 5a and 6a of the periodic table excluding Ti and Ti And a core portion made of carbonitride with at least one of M) and / or titanium carbonitride, and a carbonitride of Ti and one or more of M above. A hard phase having a two-phase structure comprising a component concentration gradient having a lower Ti concentration and a higher M concentration than the core portion, and a surface portion which is completely surrounded and distributed with respect to the core portion; And a titanium carbonitride-based cermet cutting tool having a composition comprising unavoidable impurities, wherein a part (but not less than 30 area% as measured by an electron microscopic structure inside the tool) or all of the two-phase structure hard phase is used as a core. The composition and concentration gradient of the Characterized in that it has a fracture resistant titanium carbonitride-based cermet, which is composed of a two-phase hard phase having a structure in which a part of a core is exposed to a binder phase and a surface part is discontinuously distributed. tool. 2. A binder phase mainly composed of Co and / or Ni: 3 to 20% by weight, and a carbide, nitride and carbonitride of a metal of Groups 4a, 5a and 6a of the periodic table; And a hard phase having a single-phase structure composed of one or more of these two or more solid solutions:
30% by weight, the balance being Ti and a carbonitride with one or more of the metals of Groups 4a, 5a and 6a of the Periodic Table excluding Ti (hereinafter collectively referred to as M) And / or titanium carbonitride, and a carbonitride of Ti and at least one of the above-mentioned M, but having a lower Ti concentration and a higher M concentration than the core portion. A hard carbon phase having a concentration gradient, and a hard phase having a two-phase structure composed of a surface portion which is completely surrounded and distributed with respect to the core portion, and a titanium carbonitride-based cermet cutting tool having a composition comprising unavoidable impurities, One part (however, 30 area% or more as measured by an electron microscopic structure inside the tool) or the whole of the two-phase structure hard phase has the same composition and component concentration gradient in the core and the surface, but the core has One part was exposed to the binder phase, and the surface part was discontinuously distributed. Fracture resistance superior titanium carbonitride-based cermet cutting tool, characterized in that is constituted by 2-phase structure hard phase forming.