JPS6343454B2 - - Google Patents

Description

[Detailed description of the invention]

This invention has excellent high-temperature properties, that is, high strength and hardness, as well as excellent wear resistance, plastic deformation resistance, and impact resistance, and is particularly suitable for high-speed cutting and high-feed cutting where these properties are required. The present invention relates to a method for manufacturing a sintered hard material that exhibits excellent cutting performance when used as a cutting tool. Generally, when cutting steel, increasing the cutting speed or increasing the feed rate causes the temperature of the cutting tool's cutting edge to rise, and the cutting tool's service life is shortened due to plastic deformation caused by high temperatures rather than wear. In many cases, this tendency is becoming stronger due to the recent advances in high-speed cutting and high-efficiency cutting. However, the dispersed phase currently in practical use is mainly tungsten carbide (hereinafter referred to as WC).
and titanium carbide (hereinafter referred to as TiC), while the binder phase is mainly composed of iron group metals (Fe, Ni, and
WC-based cemented carbide and TiC-based cermet, which are composed of Co), rapidly soften when the cutting edge temperature exceeds 1000°C. Even with surface-coated cemented carbide and surface-coated cermet with a hard coating layer formed on the surface, the usage conditions are such that the temperature of the cutting edge is
The temperature is limited to slightly above 1000℃. On the other hand, ceramics whose main component is aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) exhibits high hardness and excellent oxidation resistance at high temperatures, so they have been put into practical use as cutting tools for high-speed cutting. The cutting edge lacks wear resistance and is unreliable, so it is currently used at a low feed rate during high-speed cutting. In addition, in recent years, high melting point metals W, W and
A cast alloy having a structure in which Ti carbide is dispersed in layers (for example, see US Pat. No. 3,690,962)
was proposed and attracted attention, but this cast alloy has a significantly high melting point of 2700°C, and since it is a cast alloy, it is difficult to give it a shape, and its impact resistance is also insufficient. It has not yet been widely put into practical use. Furthermore, attempts have been made to manufacture alloys with the same composition as the above-mentioned cast alloys using normal powder metallurgy, but the W component has extremely poor sinterability.
As a result, it was difficult to obtain a dense sintered material, so that it could not be put to practical use as a cutting tool at all. Therefore, from the above-mentioned viewpoint, the inventors of the present invention have developed materials such as WC-based cemented carbide, TiC-based cermet, Al ₂ O _3- based ceramic,
Furthermore, it exhibits excellent cutting performance not only in cutting areas where a hard coating layer is formed on the surface of these materials, but also in high-speed cutting and high-feed cutting, which are difficult to cut in practice with these cutting tool materials. As a result of conducting research to produce cutting tool materials, we found that the main raw material powders have the chemical formula: (Ti, M ₁ ,
M ₂ )・(C, N) or {(Ti, M ₃ ), M ₁ ,
Composite metal carbonitride powder having M ₂ }・(C,N) However, M ₁ : 1 to 25 atomic % of one or two of Hf and Zr, M ₂ : 10 to 40 atomic % of W and Mo, one or more of Ta, Nb, and V in a ratio of 0.5 to 30 atomic % to M ₃ :Ti, and the remainder is 40 to 80 atomic %.
Consisting of atomic % of Ti, and the ratio of C and N is C:
(consisting of 50 to 90 atom%, N: 10 to 50 atom%),
After blending one or two of W powder and Mo powder and forming a green compact from this blended powder according to a normal powder metallurgy method, this green compact has the following properties:
When the nitriding treatment is carried out by heating and holding at a temperature within the temperature range of 1100 to 1600°C in a nitrogen-containing atmosphere, the composite metal carbonitride powder is nitrided and refined, and WC and molybdenum carbide are (hereinafter referred to as Mo ₂ C) and free carbon begin to precipitate, and then this nitrided compact is heated for 1800 to 2700 in a vacuum or in an atmosphere containing nitrogen. When sintered under conditions of heating and holding at a temperature within the temperature range of ℃, the above-mentioned precipitated
Since WC, Mo ₂ C, and free carbon are extremely active, sintering is significantly accelerated, resulting in a dense sintered material.
Moreover, the resulting sintered material has a structure in which fine composite metal carbonitrides, which have become a complete solid solution, are uniformly dispersed in the matrix. During,
Composite metal carbonitride solid solution decomposition treatment is performed under conditions of heating and holding at a temperature within the temperature range of 1300 to 1700℃,
The composite metal carbonitride solid solution has a carbonitride phase containing Ti, Ma, C, and N as main components, and M ₁ , C, and N.
The resulting sintered material has high strength and high hardness. It also has excellent wear resistance, plastic deformation resistance, and impact resistance. Therefore, this sintered hard material can be cut not only in normal cutting areas but also in high-speed cutting and high-feed cutting. They found that when used as a tool, it exhibits excellent cutting performance over a long period of time. This invention has been made based on the above knowledge, and uses the chemical formula of the dispersed phase forming component as a raw material powder:
(Ti, M ₁ , M ₂ ) (C, N) or {(Ti, M ₃ ),
Composite metal carbonitride powder having M ₁ , M ₂ }・(C, N) (M ₁ : 1 to 25 atomic % of one or two of Hf and Zr, M ₂ : 10 to 40 atoms) %W
and Mo, one or more of Ta, Nb, and V at a ratio of 0.5 to 30 atomic % to M ₃ :Ti, and the remainder is 40
~80 atomic% of Ti, and the ratio of C and N is C: 50 to 90 atomic%, N: 10 to 50 atomic%),
W powder, Mo powder, and Al, which are also binder phase forming components
Prepare powder, Ti powder, Si powder, iron group metal powder, and platinum group metal powder, and divide these raw material powders in weight%: (a) the above composite metal carbonitride powder: 20 to 70%, the above W powder and one or two of the above Mo powders: the remainder; (b) the above composite metal carbonitride powder: 20 to 70%; one of the above Al powders, Ti powders, Si powders, and iron group metal powders; Or 2 or more types: 0.5~
5%, one or two of the above W powder and Mo powder: remainder, (c) the above composite metal carbonitride powder: 20 to 70%, one or more of the above platinum group metal powders : 0.1 to 2%, one or two of the above W powder and Mo powder: the remainder, (d) the above composite metal carbonitride powder: 20 to 70%, the above Al powder, Ti powder, Si powder, and One or more types of iron group metal powder: 0.5~
5%, one or more of the above platinum group metal powders: 0.1 to 2%, one or two of the above W powder and Mo powder: the remainder, any of the above (a) to (d) After mixing, it is press-molded into a green compact, and then the green compact is heated at 1100 °C in an atmosphere containing nitrogen.
Nitriding the composite metal carbonitride powder by performing a nitriding treatment with heating and holding at a temperature within the temperature range of ~1600°C,
At the same time, one or two of tungsten carbide and molybdenum carbide and free carbon are precipitated, and then the nitrided green compact is subjected to a vacuum or an atmosphere containing nitrogen.
A sintering process is performed by heating and holding at a temperature within the temperature range of 1800 to 2700℃ to form a sintered material with a structure in which fine composite metal carbonitrides are uniformly dispersed as a complete solid solution in the matrix. , the sintered material is subsequently subjected to vacuum or nitrogen-containing atmosphere,
A composite metal carbonitride solid solution decomposition treatment is performed at a temperature within the temperature range of 1300 to 1700°C to convert the composite metal carbonitride solid solution into carbon whose main components are Ti, _M2 , C, and N. A sintered hard material for cutting tools that is decomposed into a nitride phase and a carbonitride phase whose main components are _M1 , C, and N, and has a structure in which these two fine phases are uniformly dispersed in the base material. It is characterized by the method of manufacturing it. Next, the reason why the manufacturing conditions are limited as described above in the method of the present invention will be explained. (a) Composite metal carbonitride powder (1) Ratio of M ₁ The M ₁ component has the effect of increasing the plastic deformation resistance of the material, but its proportion is higher than that of all the metals constituting the composite metal carbonitride powder. If the proportion of the components is less than 1 atomic %, the desired effect cannot be obtained, while if the proportion exceeds 25 atomic %, the impact resistance of the material will be poor. It was set at 25 atomic percent. (2) Ratio of M ₂ The M ₂ component has the effect of increasing the impact resistance of the material, but its ratio is 10 atomic % to the total metal components constituting the composite metal carbonitride powder.
If the proportion is less than 40 atomic percent, the desired effect cannot be obtained, and on the other hand, if the proportion exceeds 40 atomic percent, the wear resistance of the material will decrease.
It was determined that (3) Ratio of M ₃ The M ₃ component has the effect of further improving the plastic deformation resistance of the material, so when this property is required, the chemical formula: {(Ti, M ₃ ),
A composite metal carbonitride powder having M ₁ , M ₂ }(C, N) is used, but if the ratio thereof to Ti is less than 0.5 atomic %, the desired effect of improving plastic deformation resistance cannot be obtained. On the other hand, in the same proportion to Ti,
If it exceeds 30 atomic %, the wear resistance of the material decreases, so the ratio was determined to be 0.5 to 30 atomic % relative to Ti. (4) Ratio of Ti Ti component is the main component of composite metal carbonitride powder, and has the effect of improving the wear resistance of the material.
If the proportion is less than 40 atomic percent of the total metal components constituting the composite metal carbonitride powder, the desired effect cannot be obtained;
If it exceeds atomic percent, the impact resistance of the material decreases, so the proportion was set at 40 to 80 atom percent. (5) Ratio of C The C component has the effect of increasing the wear resistance of the material, but if the ratio is less than 50 atomic % relative to N, the N component becomes relatively too large and the desired wear resistance cannot be achieved. On the other hand, if the ratio exceeds 90 atomic percent, the N component becomes too small and the impact resistance decreases.
The proportion was set at 50 to 90 atomic percent. (6) Ratio of N The N component has the effect of increasing the impact resistance of the material, but if its ratio is less than 10 atomic % relative to C, the C component exceeds 90 atomic % as mentioned above. If the proportion exceeds 50 at%, the C component will be less than 50 at%, making it impossible to secure the desired impact resistance. Therefore, the ratio was set at 10 to 50 atomic percent. (b) Compounding amount of composite metal carbonitride powder If the compounding amount is less than 20%, the amount of carbonitride phase in the sintered hard material is too small to achieve the desired high hardness and excellent wear resistance and plastic deformation resistance. On the other hand, if the blending amount exceeds 70%, the amount of binder phase in the material becomes relatively too small and the impact resistance deteriorates.
The blending amount was set at 20-70%. (c) Al, Ti, Si, iron group metals (Fe, Ni, Co) (hereinafter collectively referred to as impact resistance improving components)
These ingredients have the effect of further improving the impact resistance of the material, so they are added as necessary when particularly impact resistance is required, but if the amount is less than 0.5%, The desired effect of improving impact resistance cannot be obtained, and if the amount exceeds 5%, the wear resistance and plastic deformation resistance tend to decrease, so the amount added is set at 0.5 to 5%. Ta. (d) Powder blending amount of platinum group metals These ingredients have the ability to further accelerate sintering.
It has the effect of making the material more dense and increasing its strength, so it is added as necessary when even higher strength is required, but if the amount is less than 0.1%, it will not improve the desired strength. no effect,
On the other hand, even if the content exceeds 2%, no further improvement in strength is observed, and considering economic efficiency, the content should be reduced.
It was set at 0.1-2%. (e) Nitriding temperature If the temperature is less than 1100℃, as mentioned above, the composite metal carbonitride powder used as the raw material powder becomes finer, and the active WC, Mo ₂ C, which has a remarkable effect of improving sinterability,
and insufficient precipitation of free carbon,
It is not possible to impart sufficient wear resistance, plastic deformation resistance, and impact resistance to the sintered material. On the other hand, if the temperature exceeds 1600℃, sintering begins to progress and the green compact becomes nitrided. is not done enough,
As a result, it becomes impossible to refine the composite metal carbonitride powder, so the nitriding temperature is
The temperature was set at 1100-1600℃. (f) Sintering temperature If the temperature is less than 1800°C, sufficient sintering cannot be performed, and as a result, cavities remain in the sintered material and impact resistance deteriorates.
On the other hand, when the temperature exceeds 2700℃, W, Ti and C
The sintering temperature was set at 1,800 to 2,700°C because a liquid phase consisting of 300°C would occur, making it difficult to maintain the shape. (g) Composite metal carbonitride solid solution decomposition treatment temperature If the temperature is less than 1300℃, the amount of carbonitride phase separated is too small, resulting in a structure in which fine and hard carbonitride phases are uniformly dispersed. On the other hand, even if the temperature exceeds 1700℃, the separation of the carbonitride phase is suppressed, making it difficult to separate out the desired amount of the carbonitride phase. Therefore, the decomposition temperature was set at 1300-1700°C. The sintered hard material produced by the method of the present invention can be used as a cutting tool by itself, but it can be used with WC-based cemented carbide, which has high toughness and contains a large amount of binder phase. It may also be used as a composite material by joining with cermet, high speed steel, etc. Further, on the surface of this sintered hard material alone or composite material, the above-mentioned conventionally known hard coating layer,
That is, carbides, nitrides, and oxides of metals from Groups 4a, 5a, and 6a of the periodic table, solid solutions of two or more of these, and a single layer of one of Al ₂ O ₃ or two or more of them. It may be used in a state where a hard coating layer consisting of multiple layers is formed with an average layer thickness of 0.5 to 15 μm using chemical vapor deposition method, etc., and in this case, it will show even better wear resistance. It is. Next, the method of the present invention will be specifically explained using examples. Examples As raw material powders, various composite metal carbonitride powders each having an average particle size of 1.5 μm and having the compositions shown in Table 1, and the same
A 1.0 μm W powder, a 0.8 μm Mo powder, a 2.5 μm impact resistance improving component powder, and a 3.0 μm platinum group metal powder were prepared, and these raw powders are shown in Table 1. After wet mixing in a ball mill for 72 hours and drying,
The powder is press-formed at a pressure of Kg/ ^mm2 , and then the green compact is subjected to nitriding, sintering, and solid solution separation treatment under the conditions shown in Table 1. Inventive materials 1 to 26 were produced. In addition, for comparison purposes, comparative materials 1 to 26 were manufactured under the same conditions except that nitriding treatment and/or solid solution separation precipitation treatment were not performed. Comparative materials 27-33 were produced under conditions where only the composition of the carbonitride powder was outside the scope of this invention. Next, cutting chips having the shape of SNP432 were prepared from each of the resulting inventive materials 1 to 26 and comparative materials 1 to 33 (hereinafter referred to as inventive material chips 1 to 26 and comparative material chips).

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[Table] (*marked: outside the scope of the present invention)

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[Table] 1 to 33), cutting test under the conditions shown below,
That is, (a) Continuous high-speed cutting test (hereinafter referred to as high-speed test) Work material: JIS/SNCM-8 (Hardness: H _B 240), Cutting speed: 220m/mm, Feed: 0.4mm/rev., Depth of cut: 2mm, cutting time: 10 minutes. (b) Continuous high-feed cutting test (hereinafter referred to as high-feed test) Work material: JIS/SNCM-8 (hardness: H _B 240), cutting speed: 100 m/mm, feed: 0.8 mm, depth of cut: 5
mm, cutting time: 10 minutes. (c) Intermittent cutting test (hereinafter referred to as intermittent test) Work material: JIS/SNCM-8 (Hardness: H _B 280), Cutting speed: 100m/mm, Feed: 0.4mm/rev., Depth of cut: 2mm, Cutting Time: 3 minutes. In the high-speed test and high-feed test mentioned above, the flank wear width and rake face wear depth of five test cutting edges were measured, and the average value was calculated. Among them, the number of cutting edges in which chipping occurred was measured. These results are shown in Table 2 for cutting chips made of ISO/P10 grade WC-based cemented carbide (conventionally referred to as chip 1) and TiC-Ni-
The results are shown together with the cutting test results of a Mo cermet (containing 15% Ni, 10% Mo) cutting chip (hereinafter referred to as conventional chip 2) under the same conditions. From the results shown in Table 2, the present invention material chips 1 to 26 do not undergo nitriding treatment and/or solid solution separation treatment in any of high-speed cutting, high-feed cutting, and interrupted cutting. Extremely superior cutting performance compared to comparative material chips 1 to 26, comparative material chips 27 to 33 whose composition of composite metal carbonitride powder as raw material powder is outside the scope of the present invention, and conventional chips 1 and 2. It is clear that As described above, according to the method of the present invention, it is possible to produce a sintered hard material that has high strength and hardness, and has excellent wear resistance, plastic deformation resistance, and impact resistance. Therefore, it is possible to practically use this sintered hard material as a cutting tool for high-speed cutting and high-feed cutting that require these characteristics, and in this case, it is possible to maintain extremely excellent cutting performance over a significantly long period of time. This brings about industrially useful effects, such as increased energy consumption.

Claims (1)

[Claims] 1. As a raw material powder, the chemical formula of the dispersed phase forming component is: (Ti, M ₁ , M ₂ ) (C, N) or {(Ti,
M ₃ ), M ₁ , M ₂ )} (C, N) composite metal carbonitride powder (M ₁ : 1 to 25 atomic % of one or two of Hf and Zr, M ₂ : 10 to 40 atomic% of one or two of W and Mo, _M3 :
The ratio of Ta, Nb, and V to Ti is 0.5 to 30 atomic % of one or more of Ta, Nb, and V, and the remainder is 40 to 80 atomic % of Ti, and the ratio of C and N is C: 50. ~90 atomic%, N: 10 to 50 atomic%), W powder as binder phase forming components, Mo powder, Al
Prepare powder, Ti powder, Si powder, iron group metal powder, and platinum group metal powder, and divide these raw material powders in weight%: (a) the above composite metal carbonitride powder: 20 to 70%, the above W powder and one or two of the above Mo powders: the remainder; (b) the above composite metal carbonitride powder: 20 to 70%; one of the above Al powders, Ti powders, Si powders, and iron group metal powders; Or 2 or more types: 0.5~
5%, one or two of the above W powder and Mo powder: remainder, (c) the above composite metal carbonitride powder: 20 to 70%, one or more of the above platinum group metal powders : 0.1 to 2%, one or two of the above W powder and Mo powder: the remainder, (d) the above composite metal carbonitride powder: 20 to 70%, the above Al powder, Ti powder, Si powder, and One or more types of iron group metal powder: 0.5~
5%, one or more of the above platinum group metal powders: 0.1 to 2%, one or two of the above W powder and Mo powder: the remainder, any of the above (a) to (d) After mixing, the powder is press-molded into a green compact, and the green compact is heated and maintained at a temperature within the temperature range of 1100 to 1600°C in an atmosphere containing nitrogen. The nitrided green compact is subjected to a sintering process in which the nitrided compact is heated and maintained at a temperature within the temperature range of 1800 to 2700°C in a vacuum or in a nitrogen-containing atmosphere, and then this sintering process is performed. A sintered hard material for cutting tools, characterized in that the material is subjected to composite metal carbonitride solid solution decomposition treatment in a vacuum or nitrogen-containing atmosphere at a temperature within the temperature range of 1300 to 1700°C. Manufacturing method.