JP4553380B2 - Titanium carbonitride-based cermet throwaway tip that exhibits excellent wear resistance in high-speed cutting with high heat generation - Google Patents

Description

  The present invention has a high-temperature hardness in which the binder phase of titanium carbonitride-based cermet (hereinafter referred to as TiCN-based cermet) is excellent, and thus exhibits excellent wear resistance in high-speed cutting with high heat generation. The present invention relates to a throw-away tip made of TiCN-based cermet.

Conventionally, a throwaway tip (hereinafter simply referred to as a cutting tip) composed of a TiCN-based cermet is known as one type of cutting used for turning, for example.
Further, the cutting tip is mass% (hereinafter,% indicates mass%),
(A) Tungsten carbide (hereinafter referred to as WC): 20 to 30%,
One or two of tantalum carbide (hereinafter referred to as TaC) and niobium carbide (hereinafter referred to as NbC) (hereinafter referred to as TaC / NbC): 5 to 10%,
One or more of zirconium carbide (hereinafter referred to as ZrC), vanadium carbide (hereinafter referred to as VC), and molybdenum carbide (hereinafter referred to as Mo ₂ C) (hereinafter referred to as ZrC / VC / Mo _2). C)): 1-5%
Co: 5-10%
Ni: 5 to 10%
Titanium carbonitride (hereinafter referred to as TiCN): remaining (however, containing 50 to 60%),
Composed of a TiCN-based cermet that is a sintered compact of a green compact having a composition comprising
(B) The TiCN-based cermet is a structure observation by a scanning electron microscope,
Hard phase: 75-93 area%,
Bond phase and inevitable impurities: the rest,
And the hard phase has a structure observation result (magnification: 10,000 times) by a scanning electron microscope, as shown in FIG.
(1) The core portion is a TiCN phase, the peripheral portion is Ti, W, one or two of Ta and Nb, and one or more composite carbonitriding of Zr, V, and Mo A first hard phase having a core structure composed of an object [hereinafter referred to as (Ti, W, Ta / Nb, Zr / V / Mo) CN] phase,
(2) a second hard phase having a core structure in which both the core portion and the peripheral portion are composed of (Ti, W, Ta / Nb, Zr / V / Mo) CN phase;
(3) a third hard phase having a single-phase structure composed of a TiCN phase,
It is composed of the above (1) to (3), and the binder phase is a proportion of the binder phase and is in mass%.
W: 1-10%
Ni: 35-60%,
Ti, one or two of Ta and Nb (hereinafter referred to as Ta / Nb), and one or more of Zr, V, and Mo (hereinafter referred to as Zr / V / Mo) ): The total amount is 5% or less,
Co and inevitable impurities: the rest,
It is also known to be made of a Co—Ni based alloy having a composition consisting of:

Furthermore, the above-mentioned cutting tip is obtained by sintering the green compact having the above composition by the following sintering conditions:
(A) From room temperature to 1400 to 1450 ° C. in a vacuum atmosphere of 10 Pa or less, 1 to 3 ° C./min. The temperature is increased at a rate of
(B) From 1400 to 1450 ° C. to 1480 to 1560 ° C. which is the sintering temperature, 1 to 3 ° C./min. The temperature is increased at a rate of, and the sintering temperature is maintained for 0.5 to 2 hours in a nitrogen atmosphere of 50 to 4000 Pa.
(C) performing furnace cooling from the sintering temperature in a vacuum atmosphere of 10 Pa or less,
It is well known that it is manufactured by sintering under the conditions comprising the steps (a) to (c) and used for continuous cutting and intermittent cutting of various steels and cast iron.
JP-A-10-110234

  In recent years, the performance of cutting machines has been remarkable. On the other hand, there has been a strong demand for labor saving and energy saving and further cost reduction for cutting work. Using a tip, the cutting speed is 300 m / min. When cutting of steel, cast iron, etc. at the above high speed, the progress of wear of the binder phase consisting of the Co-Ni alloy of TiCN-based cermet that constitutes this is remarkably accelerated by the high heat generated during cutting. Because of this, the service life is reached in a relatively short time.

In view of the above, the inventors of the present invention are composed of a Co—Ni-based TiCN-based cermet that particularly constitutes the above-described conventional cutting tip in order to improve wear resistance in high-speed cutting. As a result of conducting research focusing on the binder phase,
(A) The W component dissolved in the Co—Ni-based alloy that forms the binder phase during sintering is precipitated and dissolved in the periphery of the hard phase, and further partly dissolved in the concentric portion. In the conventional cutting tip manufactured under the sintering conditions, the precipitation solid solution ratio of the W component contained in the binder phase to the periphery of the hard phase is relatively very high, and therefore the residual content is contained in the binder phase. The proportion of the W component is low and is 1 to 10% in the binder phase.

(B) When the temperature is raised to 1200 to 1350 ° C. during the temperature increase in the vacuum atmosphere to 1400 to 1450 ° C. in the above (a) under the above-mentioned conventional sintering conditions, the Ar atmosphere is kept short for a short time. Atmosphere alternation process in which the vacuum atmosphere is alternately held for a long time, preferably a short time holding for 10 to 60 kPa in an Ar atmosphere for 1 to 5 minutes, and a short time holding for 10 to 20 Pa in a vacuum atmosphere for 5 to 20 minutes When an atmosphere alternation treatment is performed in which the vacuum atmosphere is retained twice or more, preferably 3 to 5 times each, the precipitation solid solution from the binder phase of the W component to the periphery of the hard phase during sintering is performed. As a result, the binder phase contains a very high proportion of 40 to 60% of the W component in the binder phase.

(C) When the W component is contained in the binder phase at a very high ratio of 40 to 60% in the binder phase, the resulting binder phase is further improved in high-temperature hardness. Therefore, the binder phase of TiCN-based cermet However, a cutting tip containing a high proportion of the above W should exhibit excellent wear resistance in high-speed cutting with high heat generation.
The research results shown in (a) to (c) above were obtained.

This invention was made based on the above research results,
(A) WC: 20-30%,
TaC / NbC: 5 to 10%,
ZrC / VC / Mo ₂ C: 1 to 5%,
Co: 5-10%
Ni: 5 to 10%
TiCN: remaining (however, containing 50 to 60%),
(B) The TiCN-based cermet is a structure observed with a scanning electron microscope.
Hard phase: 75-93 area%,
Bond phase and inevitable impurities: the rest,
And the hard phase has the following structure:
(1) a first hard phase having a core structure in which a core portion is made of a TiCN phase and a peripheral portion is made of a (Ti, W, Ta / Nb, Zr / V / Mo) CN phase;
(2) a second hard phase having a core structure in which both the core portion and the peripheral portion are composed of (Ti, W, Ta / Nb, Zr / V / Mo) CN phase;
(3) a third hard phase having a single-phase structure composed of a TiCN phase,
It is composed of the above (1) to (3), and the binder phase is a ratio of the binder phase,
Co: 18-33%
Ni: 20 to 35%,
Ti, Ta / Nb, Zr / V / Mo: the total amount is 5% or less,
A W-Co-Ni-based alloy having a composition consisting of W and unavoidable impurities: remaining (however, W: 40 to 60% contained),
It is characterized by a cutting tip that exhibits excellent wear resistance in high-speed cutting with high heat generation.

The reason why the compounding composition of the compact of the TiCN-based cermet and the component composition of the binder phase constituting the cutting tip of the present invention are numerically limited as described above will be described below.
(A) WC of green compact and W of binder phase
The WC powder, which is a raw material powder, is dissolved in the Co and Ni components that are the binder phase forming components at the time of sintering. Has an effect of improving the high-temperature hardness of the binder phase and contributing to improvement of wear resistance in high-speed cutting of the cutting tip. However, if the WC content is less than 20%, the W content in the binder phase is included. The ratio is less than 40% in the binder phase (hereinafter the same), and the desired wear resistance cannot be exhibited in high-speed cutting accompanied by high heat generation, while the WC compounding ratio When the content exceeds 30%, the content ratio of the W component in the binder phase increases to exceed 60%. As a result, the high-temperature strength of the binder phase itself rapidly decreases, which causes chipping during cutting (small chipping). Since it becomes easy to generate | occur | produce, the mixing | blending ratio of WC is set. And 0-30%, 40% to 60% of W component in the atmosphere alternately changing process in binder phase of TiCN-base cermet is defined to contain.

(B) Compact TaC / NbC and ZrC / VC / Mo ₂ C, and binder phase Ta / Nb and Zr / V / Mo
Similarly, TaC / NbC powder (hereinafter referred to as the former) and ZrC / VC / Mo ₂ C powder (hereinafter referred to as the latter), both of which are raw material powders, are also included in the Co and Ni components which are binder phase forming components during sintering. It dissolves and precipitates during cooling to form a hard phase, which is contained in the periphery and part of the core of the hard phase as a solid solution. The former improves the high-temperature strength of the hard phase, and the latter binds. Although it has the action of improving the wettability with the phase and improving the strength of the cermet itself, if the blending ratio is less than 5% in the former and less than 1% in the latter, the desired improvement effect cannot be obtained in the action. On the other hand, if the blending ratio exceeds 10% in the former and 5% in the latter, the content ratio in the hard phase becomes too high in any case, which only causes a decrease in the hardness of the hard phase. Not in the binder phase Since the total content ratio of a / Nb and Zr / V / Mo is higher than 5% in the ratio to the total amount with Ti, and as a result, the high-temperature hardness suddenly decreases. The blending ratio is 5 to 10% in the former and 1 to 5% in the latter, and the total content of Ta / Nb and Zr / V / Mo in the binder phase is 5% or less in the total amount with Ti. It was decided to become.

(C) Co in the green compact and Co in the binder phase
Co powder, which is a raw material powder, has the effect of improving the sinterability, forming a binder phase and improving the strength of the cutting tip. However, if the blending ratio is less than 5%, the desired sinterability is achieved. Not only cannot be ensured, but the Co content in the binder phase is also less than 18%, and the desired strength cannot be ensured for the cutting tip, while the blending ratio exceeds 10%. Then, the Co content in the binder phase after sintering becomes higher than 33%, and as a result, the high-temperature hardness of the binder phase decreases and wear progresses rapidly. The Co content in the binder phase was determined to be 18 to 33%.

(D) Ni in the green compact and Ni in the binder phase
Ni, which is a raw material powder, has a function of forming a binder phase with Co at the time of sintering and improving the heat resistance of the binder phase, thereby contributing to the improvement of the wear resistance of the cutting tip. If it is less than 10%, the content ratio of the Ni component in the binder phase after sintering becomes less than 20%, and the desired heat resistance improvement effect cannot be obtained. The Ni content in the subsequent binder phase is higher than 35%. As a result, the high-temperature strength of the binder phase is lowered, and chipping tends to occur at the cutting edge portion. And the Ni content in the binder phase was determined to be 20 to 35%.

(E) TiCN of compact and hard phase TiCN powder as raw material powder, as described above during sintering,
(1) a first hard phase having a core structure in which a core portion is made of a TiCN phase and a peripheral portion is made of a (Ti, W, Ta / Nb, Zr / V / Mo) CN phase;
(2) a second hard phase having a core structure in which both the core portion and the peripheral portion are composed of (Ti, W, Ta / Nb, Zr / V / Mo) CN phase;
(3) a third hard phase having a single-phase structure composed of a TiCN phase,
Forming the hard phase composed of the above (1) to (3) to improve the hardness of the cutting tip and thereby contribute to the improvement of wear resistance, but the blending ratio is less than 50%, The ratio of the hard phase in the cutting tip is less than 75 area%, and the desired hardness cannot be ensured. On the other hand, if the blending ratio exceeds 60%, the ratio of the hard phase is 93 area%. As a result, the strength of the cutting tip rapidly decreases, and not only chipping is likely to occur during cutting, but also the ratio of Ti to the total amount of Ta / Nb and Zr / V / Mo in the binder phase. Is higher than 5%, and as a result, the high-temperature hardness of the binder phase is lowered, which causes wear acceleration in high-speed cutting. Therefore, the blending ratio is set to 50 to 60%, and the binder phase Ti content ratio in Ta / Nb 5 defined as follows% become a percentage of the total amount of the fine Zr / V / Mo.

  In the cutting tip of this invention, the binder phase of the TiCN-based cermet constituting the cutting tip contains 40 to 60% of the W component by the above-described atmosphere change process in the temperature raising step during sintering, and as a result, the binder phase Since the high temperature hardness of the steel is rapidly improved, it exhibits excellent wear resistance in high-speed cutting with high heat generation.

  Next, the cutting tip of the present invention will be specifically described with reference to examples.

As raw material powders, TiC _0.5 N _0.5 powder, TiC _0.3 N _0.7 powder, TiC _0.15 N _0.85 powder (all above C have an average particle diameter of _{0.5 to 2} μm). / N represents an atomic ratio), WC powder, TaC powder, NbC powder, ZrC powder, VC powder, Mo ₂ C powder, Co powder, and Ni powder are prepared, and these raw material powders are blended as shown in Table 1. Compounded into the composition, wet mixed in a ball mill for 24 hours, dried, and then pressed into a green compact at a pressure of 98 MPa. The green compact was subjected to the following sintering conditions:
(A) From room temperature to 1280 ° C. in a vacuum atmosphere of 10 Pa or less, 2 ° C./min. The temperature is increased at a rate of
(B) When the temperature is raised to 1280 ° C., the short-time Ar atmosphere holding for 2 minutes in the 35 kPa Ar atmosphere and the short-time vacuum atmosphere holding for 10 minutes in the vacuum atmosphere of 10 Pa or less are shown in Table 1. Apply the alternating atmosphere change process that repeatedly repeats the number of times shown in
(C) After the atmosphere alternation process, the temperature is raised to 1420 ° C. in a vacuum atmosphere of 10 Pa or less at 2 ° C./min. The temperature is increased at a rate of
(D) 2 ° C./min. From 1420 ° C. to a predetermined sintering temperature within the range of 1480 to 1560 ° C. The temperature was increased at a rate of 1, and the sintering temperature was held for 1.5 hours in a nitrogen atmosphere of 1300 Pa,
(E) performing furnace cooling from the sintering temperature in a vacuum atmosphere of 10 Pa or less,
The present invention having a chip shape of ISO standard / CNMG120212 by sintering under the conditions consisting of the steps (a) to (e) and performing a honing process of R: 0.07 mm on the cutting edge portion after sintering. Cutting tips 1 to 15 were produced.

For comparison purposes, as shown in Table 2, regarding the TiCN powder as the raw material powder, only the above TiC _0.5 N _0.5 powder was used, and the above atmosphere in the temperature raising process to the sintering temperature Conventional cutting tips 1 to 15 were manufactured under substantially the same conditions except that the alternating processing was not performed.

  Tables 3 and 4 show the results of observation of the structure of the TiCN-based cermet constituting the cutting tip 1-15 of the present invention and the conventional cutting tips 1-15 obtained by the scanning electron microscope and the analysis result of the binder phase, respectively. Indicated.

Next, for the above-mentioned cutting tips 1-15 of the present invention and the conventional cutting tips 1-15, both of these are screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / S20C lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 380 m / min,
Incision: 1.5mm,
Feed: 0.2mm / rev,
Cutting time: 10 minutes,
Dry intermittent high-speed cutting test of carbon steel under the conditions (cutting condition A) (normal cutting speed is 250 m / min),
Work material: JIS / SCM440 round bar,
Cutting speed: 300 m / min,
Cutting depth: 1mm,
Feed: 0.2mm / rev,
Cutting time: 20 minutes,
Dry continuous high-speed cutting test (normal cutting speed is 200 m / min) of alloy steel under the conditions (referred to as cutting conditions B),
Work material: JIS / FC300 round bar,
Cutting speed: 380 m / min,
Incision: 2.5mm,
Feed: 0.3mm / rev,
Cutting time: 20 minutes,
The dry continuous high-speed cutting test (normal cutting speed is 280 m / min) of cast iron under the above conditions (referred to as cutting condition C), and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 5.

  From the results shown in Tables 1 to 5, each of the cutting chips 1 to 15 of the present invention has excellent high temperature because the binder phase of the TiCN-based cermet constituting the cutting tips contains a W component at a high rate of 40 to 60%. Since it has hardness, it exhibits excellent wear resistance even in high-speed cutting with high heat generation, whereas in the conventional cutting tips 1 to 15, all of W in the binder phase The content ratio is as low as 1 to 10%, and as a result, excellent high-temperature hardness cannot be expected for the binder phase, so that the progress of wear of the binder phase is accelerated particularly in high-speed cutting, and this is the cause. It is clear that the service life is reached in a relatively short time.

  As described above, the cutting tip of the present invention exhibits excellent wear resistance not only in cutting processing under normal conditions such as various steels and cast iron, but also in high-speed cutting processing accompanied by high heat generation, It can fully satisfy the labor-saving and energy-saving of cutting and cost reduction.

It is a copying figure which shows the structure | tissue observation result (magnification | multiplying_factor of 10,000 times) by the scanning electron microscope of the TiCN base cermet which comprises a cutting tip.

Claims (1)

(A) By mass%, tungsten carbide: 20-30%,
One or two of tantalum carbide and niobium carbide: 5 to 10%,
One or two of zirconium carbide, vanadium carbide, and molybdenum carbide: 1 to 5%,
Co: 5-10%
Ni: 5 to 10%
Titanium carbonitride: remaining (however, containing 50 to 60%),
It is composed of a titanium carbonitride-based cermet that is a sintered compact of a green compact having a composition comprising:
(B) The titanium carbonitride-based cermet is a structure observation by a scanning electron microscope,
Hard phase: 75-93 area%,
Bond phase and inevitable impurities: the rest,
And the hard phase has the following structure:
(1) The core is a titanium carbonitride phase, the periphery is Ti, W, one or two of Ta and Nb, and one or more of Zr, V, and Mo. A first hard phase having a core structure composed of a carbonitride [hereinafter referred to as (Ti, W, Ta / Nb, Zr / V / Mo) CN] phase;
(2) a second hard phase having a core structure in which both the core portion and the peripheral portion are composed of (Ti, W, Ta / Nb, Zr / V / Mo) CN phase;
(3) a third hard phase having a single-phase structure composed of a titanium carbonitride phase,
It is composed of the above (1) to (3), and the binder phase is a proportion of the binder phase and is in mass%.
Co: 18-33%
Ni: 20 to 35%,
Ti, one or two of Ta and Nb, and one or more of Zr, V, and Mo: the total amount is 5% or less,
W and inevitable impurities: remaining (however, W: 40 to 60% contained),
A W-Co-Ni alloy having a composition consisting of:
Titanium carbonitride-based cermet throwaway tip that demonstrates excellent wear resistance in high-speed cutting with high heat generation.

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