JP2000038635A - Cutting tool made of titanium carbonitride series cermet excellent in thermal impact resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool made of cermet excellent in thermal shock resistance. SOLUTION: A cutting tool made of cermet is composed of cermet showing a structure in which the ratio of hard phase occupies 80 to 95 area %, and the balance bonding phase essentially consisting of Co and/or Ni with inevitable impurities by structural observation by a scanning type electron microscope, in which the hard phase is composed of (a) primary hard phase in which the core parts are composed of (Ti, Ta, Zr) CN, and the circumferential parts are composed of (Ti, W, Zr, Mo, Ta, Nb) CN and (b) secondary hard phase in which the core parts are composed of (Ti, W, Mo) CN, and the circumferential parts are composed of (Ti, W, Zr, Mo, Ta, Nb) CN having substantially two kinds of core structures, the hardness of the core parts in the primary hard phases is relatively higher than that in the secondary hard phase, and the ratio of the primary hard phase is 50 to 80 area % at the ratio occupied in the hard phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting edge which is excellent in thermal shock resistance, and therefore has a strong thermal shock, for example, when used for high-speed or high-cut intermittent cutting. The present invention relates to a titanium carbonitride-based cermet cutting tool (hereinafter, referred to as a cermet cutting tool) which exhibits excellent cutting performance for a long period of time without occurrence of chipping or chipping (micro chipping).

[0002]

2. Description of the Related Art Conventionally, as described in, for example, JP-A-8-192304, a cutting tool made of cermet is known. Occupies 95% by area, the rest is C
The hard phase has a cored structure consisting of a core and a peripheral portion, and the hard phase has a cored structure composed of a core portion and a peripheral portion. Ti-based composite carbonitride solid solution obtained by substituting a part of Ti in titanium nitride (hereinafter referred to as TiCN) with one or more of metals of groups 4a, 5a and 6a of the periodic table excluding Ti , (Ti, M) CN] is also known as a cermet (hereinafter simply referred to as a cermet). The cermet cutting tool is widely used for interrupted cutting because it has good fracture resistance as well as continuous cutting with steel or cast iron.

[0003]

On the other hand, in recent years, there is a strong demand for labor saving and energy saving in cutting work, and accordingly, cutting work has been accelerated and heavy cutting such as high feed and high cutting has been performed. In the above-mentioned conventional cermet cutting tools, there is a tendency to cut this with a particularly strong thermal shock,
For example, when high-feed or high-cut intermittent cutting is used for high-speed cutting, the cutting edge is liable to be damaged, and the service life is relatively short in the present situation.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoints, the above-mentioned conventional cermet cutting tool was focused on, and as a result of researching to improve the thermal shock resistance of the cutting tool, the hard phase of the cermet forming the cermet cutting tool was identified as (a) The core portion is made of a Ti-based composite carbonitride solid solution obtained by substituting a part of Ti in TiCN with Ta and Zr [hereinafter, referred to as (Ti, Ta, Zr) CN], and has a composition formula: Ti _{1 - (x + y) Ta x} Zr y) C
When expressed in _1-z N _z, both in terms of atomic ratio, x: 0.
1-0.3, y: 0.01-0.2, z: 0.2-0.
(Ti, Ta, Zr) CN satisfying No. 6 is preferable, and the peripheral portion is a composite carbonitride solid solution of Ti, W, Zr, Mo, Ta, and Nb [hereinafter, (Ti, W, Zr,
Mo, Ta, Nb) CN].
(B) Ti-based composite carbonitride solid solution in which the core part is obtained by substituting part of Ti in TiCN with W and Mo [hereinafter, referred to as “
(Ti, W, Mo) CN], which are represented by the composition formula: Ti _{1-(a + b)} W _a Mo _b ) C _{1 -c} N _c , where all are represented by the atomic ratio a : 0.1 to 0.4, b: 0.
0.5 to 0.2, c: 0.2 to 0.6 (Ti,
(W, Mo) CN is preferable, and the peripheral portion is also a second hard phase also made of (Ti, W, Zr, Mo, Ta, Nb) CN (Ti-based composite carbonitride solid solution). When constituted by the first and second hard phases having substantially two types of cored structures of (b) and (b), the core of the first hard phase has a higher hardness than TiCN, while the second hard phase has a higher hardness. The hardness of the core of the hard phase is lower than that of TiCN, and as a result, the hardness difference between the core of the first hard phase and the core of the second hard phase is relatively large. A cermet having two types of hard phases having a large hardness difference in part hardness has excellent thermal shock resistance, and therefore, a cutting tool composed of the cermet can be used under conditions with strong thermal shock. Shows excellent fracture resistance even in cutting work, and excellent cutting performance over a long period of time The than is obtained the results of a study that demonstrated.

The present invention has been made on the basis of the above research results, and the structure of the hard phase accounts for 80 to 95% by area, and the balance is C
FIG. 4 shows a structure composed of a binder phase containing o and / or Ni as main components and unavoidable impurities. The hard phase is composed of (a) a core part of (Ti, Ta, Zr) CN, and preferably a composition formula: Ti
When expressed in _{1- (x + y) Ta x} Zr y) C 1-z N z, both in terms of atomic ratio, x: 0.1~0.3, y: 0.01~
0.2, z: 0.2 to 0.6 are satisfied (Ti, Ta,
Zr) CN, and the peripheral portion is (Ti, W, Zr, M
o, Ta, Nb) The first hard phase composed of CN, (b) the core part is (Ti, W, Mo) CN, preferably the composition formula: Ti
When expressed in _{1- (a + b) W a} Mo b) C 1-c N c, both in terms of atomic ratio, a: 0.1~0.4, b: 0.05~
0.2, c: satisfy 0.2 to 0.6 (Ti, W, M
o) Consisting of CN, the periphery of which is (Ti, W, Zr, Mo,
Ta, Nb) A second hard phase composed of CN, a first and a second hard phase having substantially two types of cored structures (a) and (b), and a core of the first hard phase. The partial hardness is relatively higher than the core hardness of the second hard phase, and the ratio of the first hard phase is 50 to 80 in the ratio of the hard phase to the hard phase.
The present invention is characterized by a cutting tool made of cermet having excellent thermal shock resistance and composed of cermet having an area%.

Further, in the cermet cutting tool of the present invention, the component composition of the cermet constituting the cermet is limited as described above for the following reason. (A) Proportion of hard phase If the proportion is less than 80 area%, the proportion of the binder phase is relatively too high, and it is not possible to secure desired excellent wear resistance, while the proportion is 95 area%. On the contrary, if the ratio exceeds 80%, on the contrary, the ratio of the binder phase becomes too low, and the desired sinterability cannot be obtained. As a result, it becomes difficult to secure the strength required for the cutting tool. ９５95% by area, preferably 85 to 90% by area.

(B) Proportion of the first hard phase As described above, in the cermet in which the hard phase has a substantially cored structure, the first hard phase having a relatively hard core and the second hard phase having a soft core are relatively hard. Coexistence provides excellent thermal shock resistance. In this case, to ensure the desired high hardness higher than the hardness with the TiCN to the core of the first hard phase, this composition _{formula: Ti 1- (x + y)} Ta x Zr y)
When represented by C _1-z N _z , all of them are represented by atomic ratio and x:
0.1-0.3, y: 0.01-0.2, z: 0.2-
As described above, it is desirable to satisfy 0.6, because when either x value or y value is less than x: 0.1 or less than y: 0.01, the desired hardness is obtained. When the effect of improving the height is not obtained and one of the x value and the y value exceeds x: 0.3 and y: 0.2,
It becomes too hard, which causes chipping. Further, the C component has an effect of securing hardness, and the N component has an effect of securing toughness. When the ratio of the C component is too large, the toughness is insufficient. On the contrary, when the z value exceeds 0.6, the ratio of the C component is relatively too small, the hardness is insufficient, and the desired hardness and toughness are provided. It can be difficult. Also,
In order to secure a desired hardness relatively lower than the hardness of TiCN in the core of the second hard phase, it is necessary to use the composition formula: Ti
When expressed in _{1- (a + b) W a} Mo b) C 1-c N c, both in terms of atomic ratio, a: 0.1~0.4, b: 0.05~
As described above, it is desirable to satisfy 0.2 and c: 0.2 to 0.6 because one of the a value and the b value is less than a: 0.1 and y: If it is less than 0.05, the desired hardness lowering effect cannot be obtained, and either one of the a value and the b value is a: 0.4 and b:
If it exceeds 0.2, the hardness of the core becomes too low, which may promote the progress of wear.
The component and the N component are for the same reason as described above. Further, when the proportion of the first hard phase is less than 50 area% or more than 80 area% in the proportion of the hard phase, the proportion of the second hard phase relatively exceeds 50 area%, Although it is less than 20 area%, it has been empirically found that in this case, the desired excellent thermal shock resistance cannot be obtained. 50-80%
Area%, desirably 60 to 70 area%.

[0008]

Next, the cermet cutting tool of the present invention will be described in detail with reference to examples. (A) (Ti _0.70 Ta _0.20 Zr _0.10 ) C N powder (hereinafter a powder), each having a predetermined average particle size in the range of 0.5 to 2 μm as the raw material powder for forming the first hard phase core portion. (B) (Ti _0.89 Ta _0.10 Zr _0.01 ) C N powder (hereinafter referred to as b powder), (c) (Ti _0.50 Ta _0.30 Zr _0.20 ) C N powder (hereinafter referred to as c powder), (D) (Ti _0.70 Ta _0.10 Zr _0.20 ) C N powder (hereinafter referred to as d powder), (e) (Ti _0.69 Ta _0.30 Zr _0.01 ) C N powder (hereinafter referred to as e powder), and similarly second hard (A) (Ti _0.60 W _0.30 Mo _0.10 ) C N powder (hereinafter referred to as “a powder”) having a predetermined average particle size in a range of 0.5 to 2 μm as a raw material powder for forming a phase core portion. , _{(i) (Ti 0.85 W 0.10 Mo 0.05} ) C N powder (hereinafter, referred to as Lee powder), (c _{(Ti 0.40 W 0.40 Mo 0.20)} C N powder (hereinafter, referred to as c powder), _{(d) (Ti 0.70 W 0.10 Mo 0.20} ) C N powder (hereinafter, referred to as d powder), (e) (Ti _0.55 W _0.40 Mo _0.05 ) C N powder (hereinafter referred to as “o powder”) [All of the above composition formulas are represented by atomic ratios], and further, as a raw material powder for forming the first and second hard phase peripheral portions, both are 0.5 Having a predetermined average particle size in the range of ２2 μm,
TaC powder, NbC powder, WC powder, and Mo ₂ C powder, and a raw material powder for forming a binder phase, Co powder, and Ni
Powders are prepared, and each of these raw material powders is blended in the composition shown in Table 1, wet-mixed in a ball mill for 24 hours, dried, and then pressed into a predetermined shape at a pressure of 1 ton / cm ^{2 to} obtain a green compact. AP were formed. Then, the green compacts A to P were sintered under the following sintering conditions, that is, 10 torr.
r in a nitrogen atmosphere at room temperature to 5 ° C./min. After the temperature was raised to 1350 ° C. at a temperature rising rate of 1350 ° C. and maintained at 1350 ° C. for 1.5 hours, the temperature was raised to a predetermined sintering temperature in the range of 1500 to 1600 ° C. at the same temperature rising rate, For 1.5 hours and sintering under furnace-cooling sintering conditions.
Cermet cutting tools of the present invention (hereinafter, referred to as the present cermet tool) 1 to 10 and comparative cermet cutting tools (hereinafter, referred to as comparative cermet tools) 1 to 6 each having a throwaway tip shape of O standard CNMG120408, respectively. Manufactured.

Next, regarding the various cermet tools obtained as a result, the cermet structures constituting the cermet tools are described as follows.
First, observation is performed using an Auger electron spectrometer, and the composition of each core of the hard phase is measured and classified (in this case, the first hard phase core and the second hard phase core are substantially the same as the composition of the raw material powder). It has the same composition, and all its peripheral parts are (Ti, W,
Zr, Mo, Ta, Nb) CN were confirmed), and the ratio of each of the classified hard phases was measured using a scanning electron microscope and an image analyzer. Table 2 shows the results of these measurements. In the above-mentioned cermet structure observation, the cermet tools 3, 5, 7, and 9 of the present invention, and the comparative cermet tools 2, 4, and 5,
Microstructures in which the unreacted fine carbides were dispersed in a small proportion (the proportions could not be measured due to the fineness) were observed in the respective binder phases.

Further, in order to evaluate the thermal shock resistance of the above various cermet tools, cutting conditions accompanied by a strong thermal shock, that is, a work material: JIS SNCM439, a circle with four longitudinal grooves at regular intervals in the longitudinal direction. Rod, cutting speed: 350 m / min. Feed: 0.15 mm / rev. Notch: 2.5 mm. , Cutting time: 3 minutes, Dry high-incision high-speed intermittent cutting test of steel under the following conditions: Work material: JIS S45C, 4 longitudinally spaced round bars with equally spaced longitudinal grooves, Cutting speed: 350 m / min. Feed: 0.35 mm / rev. Notch: 1.0 mm. Under the conditions of cutting time: 3 minutes, a dry high-feed high-speed intermittent cutting test of steel was performed, and the flank wear width of the cutting edge was measured in each cutting test. Table 2 shows the results of these measurements.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

From the results shown in Table 2, the cermet tools 1 to 10 of the present invention have excellent thermal shock resistance due to the coexistence of the relatively hard first hard phase and the soft second hard phase. Since it is equipped, it shows excellent wear resistance without chipping or chipping of the cutting edge even in cutting with strong thermal shock as described above, whereas the hard phase is the first hard phase Alternatively, it is clear that the comparative cermet tools 1 to 6 made of any one of the second hard phases cause chipping or chipping of the cutting edge due to thermal shock generated during cutting, leading to a relatively short service life. is there. As described above, the cermet cutting tool of the present invention has excellent thermal shock resistance. Therefore, for example, not only continuous cutting of steel but also intermittent cutting at high speed under heavy cutting conditions can be performed. Excellent cutting performance is exhibited over a long period of time without chipping or chipping of the blade, and therefore greatly contributes to labor saving and energy saving in cutting.

[Procedure amendment]

[Submission date] August 3, 1998 (1998.8.3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

[0008]

Next, the cermet cutting tool of the present invention will be described in detail with reference to examples. (A) (Ti _0.70 Ta _0.20 Zr _0.10 ) C _0.50 N _0.50 powder (hereinafter, referred to as “first hard phase core portion forming raw material powder”), each having a predetermined average particle size in the range of 0.5 to 2 μm. a powder), (b) (Ti _0.89 Ta _0.10 Zr _0.01 ) C _0.70 N _0.30 powder (hereinafter referred to as b powder), (c) (Ti _0.50 Ta _0.30 Zr _0.20 ) C _0.50 N _0.50 powder (hereinafter, referred to as c) powder; (d) (Ti _0.70 Ta _0.10 Zr _0.20 ) C _0.80 N _0.20 powder (hereinafter referred to as d powder); (e) (Ti _0.69 Ta _0.30 Zr _0.01 ) C _0.40 N _0.60 powder (hereinafter, referred to as d powder). e) as raw material powders for forming the second hard phase core portion, each having a predetermined average particle size in the range of 0.5 to 2 μm. (A) (Ti _0.60 W _0.30 Mo _0.10 ) C _0.50 N _0.50 powder (hereinafter, referred to as a powder), (b) (Ti _0.85 W _0.10 Mo _0.05 C _0.70 N _0.30 powder (hereinafter, referred to as Lee powder), _{(c) (Ti 0.40 W 0.40 Mo 0.20} ) C 0.50 N 0.50 powder (hereinafter, referred to as c powder), _{(d) (Ti 0.70 W 0.10 Mo 0.20} ) C _0.50 N _0.50 powder (hereinafter referred to as “E powder”), (E) (Ti _0.55 W _0.40 Mo _0.05 ) C _0.70 N _0.30 powder (hereinafter referred to as “O powder”) [All the above composition formulas are represented by atomic ratio. ], And as the first and second hard phase peripheral part forming raw material powders, each has a predetermined average particle size in the range of 0.5 to 2 μm,
TaC powder, NbC powder, WC powder, and Mo ₂ C powder, and a raw material powder for forming a binder phase, Co powder, and Ni
Powders are prepared, and each of these raw material powders is blended in the composition shown in Table 1, wet-mixed in a ball mill for 24 hours, dried, and then pressed into a predetermined shape at a pressure of 1 ton / cm ^{2 to} obtain a green compact. AP were formed. Then, the green compacts A to P were sintered under the following sintering conditions, that is, 10 torr.
r in a nitrogen atmosphere at room temperature to 5 ° C./min. After the temperature was raised to 1350 ° C. at a temperature rising rate of 1350 ° C. and maintained at 1350 ° C. for 1.5 hours, the temperature was raised to a predetermined sintering temperature in the range of 1500 to 1600 ° C. at the same temperature rising rate, For 1.5 hours and sintering under furnace-cooling sintering conditions.
Cermet cutting tools of the present invention (hereinafter, referred to as the present cermet tool) 1 to 10 and comparative cermet cutting tools (hereinafter, referred to as comparative cermet tools) 1 to 6 each having a throwaway tip shape of O standard CNMG120408, respectively. Manufactured.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hidemitsu Takaoka 1511 Furamagi, Ishishita-cho, Yuki-gun, Ibaraki Prefecture Inside the Tsukuba Works, Mitsubishi Materials Corp. 1511 Mitsubishi Materials Corporation Tsukuba Works (72) Inventor Katsuhisa Nonaka 1511 Furusagi, Ishishita-cho, Yuki-gun, Ibaraki Prefecture Mitsubishi Materials Corporation Tsukuba Works F-term (reference)

Claims (1)

[Claims] 1. Observation of a structure by a scanning electron microscope shows a structure in which the proportion of a hard phase occupies 80 to 95 area%, and the balance is composed of a binder phase containing Co and / or Ni as a main component and unavoidable impurities, (A) The core part is a part of Ti in titanium carbonitride
A first hard phase composed of a Ti-based composite carbonitride solid solution substituted with Zr and Zr, and having a peripheral portion composed of a composite carbonitride solid solution of Ti, W, Zr, Mo, Ta, and Nb; Part is composed of a Ti-based composite carbonitride solid solution in which part of Ti in titanium carbonitride is replaced by W and Mo, and the peripheral part is a composite carbonitride of Ti, W, Zr, Mo, Ta and Nb. A second hard phase composed of a solid solution, a first and a second hard phase having substantially two types of cored structures (a) and (b), and a core hardness of the first hard phase. Was composed of a titanium carbonitride-based cermet having a relative hardness higher than the core hardness of the second hard phase and a proportion of the first hard phase in the hard phase of 50 to 80 area%. Titanium carbonitride-based cermet cutting with excellent thermal shock resistance tool.