JPS5854183B2 - Oxygen-containing tungsten carbide-based sintered hard alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oxygen-containing tungsten carbide (hereinafter referred to as WC)-based sintered hard alloy that exhibits outstanding cutting properties, particularly when used as a cutting tool material.

Conventionally, sintered hard alloys generally include (a) WCC cemented carbide containing WC as a main component (
b) Titanium carbide (hereinafter referred to as TiC), titanium nitride (hereinafter referred to as TiN), or titanium carbonitride (hereinafter referred to as T)
(c) ceramics containing aluminum oxide (hereinafter referred to as Al2O3) as a main component; (c) ceramics containing aluminum oxide (hereinafter referred to as Al2O3) as a main component;

Among these conventional sintered hard alloys, ceramics are superior to the above-mentioned WC in terms of toughness when used as cutting tools.
Since it is inferior to C cemented carbide and cermet, Al2
The excellent heat resistance, oxidation resistance, and welding resistance of O3 cannot be fully utilized, and therefore it is only put into practical use in a few limited fields.

Furthermore, most of the above cermets are mainly composed of TIC, and since TiC has inferior toughness and plastic deformation resistance compared to WC, these TiC-based cermets cannot be used during interrupted cutting under heavy loads. There is a problem in that TiC-based cermets are prone to chipping when used for cutting, black scale cutting, and cutting of high-hardness materials.Therefore, research on improving the toughness of TiC-based cermets has been actively conducted. Cermet with W or WC, titanium nitride (
It is being considered to improve the toughness by adding and containing components such as TiN (hereinafter referred to as TiN) or T1CN.

It is true that W or WC is added to the conventional TiC-based cermet mentioned above.
When the component is added, this W or WC becomes TiC.
TiC forms a solid solution in the surrounding structure called the intermediate phase surrounding TiC, forming a double structure with TiC as the core, improving the wettability between the hard phase and the binder phase. Since there is essentially no improvement in strength, this cermet has not yet achieved high strength.

Furthermore, when TiN is added to the conventional TiC-based cermet, as is well known, this TiN is the most stable compound among transition metal nitrides, along with zirconium nitride (hereinafter referred to as ZrN), and has high thermal conductivity. In addition to having excellent heat shock resistance and thermal shock resistance, it also suppresses the grain growth of the hard phase during sintering and suppresses the development of relatively brittle surrounding structures, improving the toughness of the cermet. However, in order to impart the desired toughness to the cermet, it is necessary to add a large amount of it.

However, when such a large amount of TiN is added to a cermet, the wettability of TiN with the binder phase deteriorates, and cavities and bores (small pores) are easily formed in the cermet structure, resulting in a significant decrease in the strength of the cermet. At present, it is not possible to contain a large amount of TiN, and as a result, it is not possible to obtain a product with the desired excellent toughness.

Furthermore, as mentioned above, it has been considered to improve the toughness of cermets by adding T1CN to TiC-based cermets or by including T1CN as a main component. Judging from the fact that there is almost no difference in alloy properties and cutting performance when compared to the above-mentioned cermets that contain cermets for the same purpose, it is clear that the T1CN-containing cermets and the TiCH-based cermets have essentially high strength. It is understood that the material is not strong and durable.

- As mentioned above, W or WC is applied to TiC-based cermet.
In addition, in cermets containing TiN or T1CN, as well as in TiN-based and T1CN-based cermets, the hard phase is fine, so the alloy hardness and transverse rupture strength of the alloy are somewhat improved. There are, but
Since the strength of the hard phase is not essentially improved, it does not have high strength, and furthermore, its toughness is not comparable to WCC cemented carbide.

As described above, the conventional WCC cemented carbide is superior to the conventional cermet in terms of toughness, but the WC component is not as good as the TiC component in terms of heat resistance, oxidation resistance, and welding resistance. When the WCC cemented carbide is used for cutting, which requires heat resistance, oxidation resistance, and welding resistance, it exhibits significantly inferior cutting performance compared to the TiC-based cermet.

Because of this, WCC components also have heat resistance, oxidation resistance,
and (W, Ti)C components and T with excellent welding resistance.
WC (W, T
i) C-TaCC.

Among the WCC type cemented carbide, PLO grade is mainly used for high-speed cutting, but this PIO
Depending on the grade, when the cutting speed exceeds 200 m/m272, cutting tool wear, especially crater wear, is so severe that it is currently impossible to use it practically.

Furthermore, cutting tools used for heavy cutting, where the heat generation at the initial speed is high and the stress applied to the cutting edge is high, are required to have high heat resistance, plastic deformation resistance, and impact resistance. P30 grade of WCC cemented carbide JIS classification is often used for cemented carbide, but this P30 grade has heat resistance and plastic deformation resistance, but has insufficient impact resistance. Many products that have impact resistance lack heat resistance and plastic deformation resistance, so P30 grade does not have all of heat resistance, plastic deformation resistance, and impact resistance. Therefore, when used for heavy cutting with large feed and depth of cut, it does not exhibit excellent cutting performance.

As mentioned above, conventional WCC cemented carbide and conventional cermets each have cutting areas in which they are not good at cutting, and in particular, in cutting where toughness is important, it is better to use toughness rather than cermets that have many limiting conditions. The above-mentioned WCC cemented carbide will be widely used.

However, as mentioned above, conventional WC-based sintered alloys have not yet shown sufficiently satisfactory cutting performance not only in high-speed cutting but also in heavy-duty cutting, where their toughness can be utilized. In order to expand the cutting area of cemented carbide, it is necessary to simultaneously improve its heat resistance, oxidation resistance, welding resistance, plastic deformation resistance, and impact resistance.

From the above-mentioned viewpoints, the present inventors conducted research to obtain a WC-based sintered hard alloy that simultaneously has heat resistance, oxidation resistance, welding resistance, plastic deformation resistance, and impact resistance. Results (a) Iron group metals containing one or more chromium group metals as necessary for the purpose of improving the high temperature strength of the alloy and the wettability with the hard phase during sintering. 5 as a binder phase forming component with one or more of the following.
WC-based sintered hard alloy containing ~30% by volume,
Instead of the (W, Ti)C and TaC components that have been used for many years, the molar ratio of oxygen to the total amount of oxygen and either or both of carbon and nitrogen is 0.2 or less. , Ti carbonates, nitride oxides, and carbonitride oxides, as well as Ti and 4 of the periodic table excluding Ti.
One or more carbonates, nitrides, and carbonitrides (hereinafter collectively referred to as carbonitrides) of one or more of group a, 5a, and 6a metals When two or more types are contained in a ratio of 1 to 50% by volume, the carbon/nitride oxide will: (1) be uniformly and finely dispersed in a spheroidal state;

■ Particles are less likely to stick together.

■ Compared to (W, Ti)C component, heat resistance, oxidation resistance,
It has excellent welding resistance and does not reduce alloy strength.

■ Suppress WC grain growth.

Due to these characteristics, the WC-based sintered hard alloy has excellent heat resistance, oxidation resistance, and welding resistance, and also has excellent impact resistance due to the absence of coarse WC. It will now exhibit excellent cutting performance when used in high-speed cutting and heavy-duty cutting, which WCC cemented carbides have traditionally been weak at.

(b) 4a and 5a of the periodic table in the range of 1 to 50% by volume to the WC-based sintered hard alloy shown in item (a) above.

and carbides, nitrides, and carbonitrides of Group 6a metals (
When one or more of the following (hereinafter collectively referred to as carbon/nitrides) is contained, the wear resistance of the alloy is further improved.

The findings shown in sections (a) and (b) above were obtained.

This invention has been made based on the above knowledge, and the technical reason for limiting the numerical values as described above will be explained below.

(1) Content of carbon/nitride oxides If the content is less than 1% by volume, the desired excellent heat resistance, oxidation resistance, welding resistance, and impact resistance cannot be imparted to the alloy. On the other hand, if the content exceeds 50% by volume, the sinterability will deteriorate, and cavities and bores will easily form in the alloy structure, reducing the impact resistance. It was determined that

(2) 0/(C+0), 0/(N
. The molar ratio was limited to 0.2 or less because the impact resistance would be lowered.

(3) Content of carbon/nitride If the content is less than 1% by volume, the desired wear resistance cannot be ensured, so it is necessary to contain 1% or more.
If the content exceeds 50% by volume, the excellent plastic deformation resistance and impact resistance of WC cannot be fully exhibited, so the content is set at 1 to 50% by volume.

(4) Content of chromium group metals and iron group metals If the content is less than 5% by volume, the impact resistance of the alloy will deteriorate, while if the content exceeds 30% by volume, the wear resistance of the alloy will deteriorate. Since it will deteriorate, its content should be reduced to 5 to 3
It was set as 0% by volume.

The WC-based sintered hard alloy of the present invention can be manufactured by a normal powder metallurgy method, but the carbon/nitride powder as the raw material powder may be, for example, (a) titanium oxide (T 102) powder. First, TiC powder and carbon (C) powder are mixed and reacted at a temperature of 1600 to 2000°C to produce titanium carbonate (hereinafter referred to as Ti(CO)) powder, and furthermore, this Ti(CO) powder and TiN powder or T
Titanium carbonitride oxide (hereinafter referred to as Ti(CNO)) powder is produced by reacting the mixed powder with i(CN) powder at the above temperature.

(b) Add the above Ti(CO) powder to N2 or NH3
Ti(CNO) powder is produced by heating and reacting in an atmosphere at a temperature of 1600 to 2000'C.

(c) TiO to Ti(CN) powder or TiN powder
2 powder and C powder are mixed and the temperature is 1600-2000℃.
Ti(CNO) powder or titanium nitride oxide (hereinafter referred to as Ti(NO)) powder is produced by the reaction.

(d) Part of the Ti in the above Ti (CNO) is 4 in the periodic table.
When producing a powder substituted with one or more metals of group a, 5a, and 6a, the above Tie 2. Ti
4a, 5a of the periodic table as required for C, TiN, Ti(CN) powder.

It is produced by mixing one or more of group 6a metal oxide powder, carbide powder, nitride powder, and carbonitride powder, and similarly subjecting the mixture to a high-temperature heating reaction.

It can be adjusted by methods such as

Next, the WC-based sintered hard alloy of the present invention will be explained through examples and in comparison with comparative examples.

As the raw material powder for the example, ■ W powder having an average particle size of 1.2μ, ■ Same as 1
．． 5 μm, and the molar ratio of C:N:0 is 0.55:
0.30: 0.15, or 0.15/(0,
55+0.30+0.15)-0,15 Ti(C0,55・NO,3000,15
) powder, ■ has the same 1.5μ door, and the molar ratio of C:N:O is 0.45:0.30:0.25, that is, 0.
25/(0,45+0.30+0.25)=0.25
T i (C0,45' NO,
3000,25) Powder, ■ 1.5 μm, Ti
: W=55%:45%, C:N: 0=0.5
: 0.4 : 0.1 molar ratio, (T i
0.55W4), 45X C0,5NO,40o,
t) Powder, ■ 1.5μm, Ti:Ta
:Zr=70%:20%:10%, C:N:
with a molar ratio of 0=0.5:0.3:0.2, (
TI 0.4 T a □, 2 Z r o, 1) (C
0.5 No. 300.2) Powder, ■ Has the same 1.5 μ door, Ti: Nb: V-4
0%:50%:10%, C:N:0=0.4:
(T I □, 4
Nbo, 5 V□, t ) (Co, 4 N0050o
, t) powder, ■ having the same 1.5 μm, T i :
Mo: Cr=70%:29%:1%, C:N:0=
(T
lo, 70M0O, 2gCro, ol) (C0,65N
O, 2500, 15) Powder,■ Has the same 1.5μ door,
C: with a molar ratio of 0=0.85:0.15,
T i (C0,8500,15) powder, ■ 1.5
T i (NO, 8500, 15) powder with μ seeds and a molar ratio of N: 0 = 0.85: 0.15;
[Phase] Same 1.5μm, Ti:Ta=80%:2
0%, with a molar ratio of C:0=0.85:0.15,
(T jo, go Taa20 X C0,8500,
15) Powder, 0 Same 1.5μ door, C: 0 = 0.7
T i (C0,750
o25) Powder, 0 TaC powder of the same 1 μm size, 0 NbC powder of the same 1.5 μm size, ■ VC powder of the same 2.5 μm size, [Phase] ZrC powder of the same 1.5 μm size, [Phase] Same 1.5 μm size Has a door, Ti:W=90%:10
% of (T i qoWo, 1) C powder, 0 same 1.5
μn TiN powder, [Phase] Same 1.5 μm TaN powder, [Phase] Same 1.5 μm door, C: N=0.7:
T i (C0,7No, 3
) Powder, [Phase] Same 1.8μ circle, Ti:W=90
%=10%, with a molar ratio of C:N=0.7:0.3 (Tio,9Wo,1)・(C0,7
Nos ) powder, O has the same 1.5μm, Ta:Nb=
80%: 20% (T a o, B N b o2 )
Powder, [Phase] Co grain powder with the same 1.2μ door [Phase] Ni powder with the same 1μ door, [Phase] Fe powder with the same 1.5μ door, Mo powder with the same 1μ O, [Phase] Same 0. Prepare W powder with an 8μ door, [F] Cr powder with a 1.3μ door, and mix these raw powders into the composition shown in Table 1, grind and mix in a ball mill, and then After press-molding the mixed powder under normal conditions to form a green compact, the green compact is heated in a vacuum at a temperature of 1
Invention alloys 1 to 10 and comparative alloys 1 to 8 having substantially the same composition as the blended composition were manufactured by sintering at 450'C for 1 hour.

In addition, all of Comparative Alloys 1 to 8 are out of the scope of the present invention in terms of the oxygen molar ratio in the carbon/nitride oxide and the content of any one of the constituent components.

Next, alloys 1 to 10 of the present invention. Comparative alloys 1 to 8, and Plo (wt%), which is conventionally known as a material for cutting tools.
It has a composition of 8% Co-18% TiC-5% TaC remaining WC.

From Cl5 (Cemented Carbide Tool Association standard) 5NP432, a cutting test tip was manufactured from Cl5 (hereinafter referred to as conventional alloy), with a shape conforming to 5NP432, work material: SNCM-8 (hardness: HB220), tip: 0.03 mm. Honing, cutting speed: 200 m/=C feed: 0.2 mm/rev) depth of cut: 2 mm.

Continuous steel high-speed cutting test under the conditions of cutting time: 10 knees, and work material: SN
CM-8 (hardness: HB270), tip: 0.03 mm honing, cutting speed: 100 m/min.

Delivery: o, 3/rev・) Depth of cut: 2myrt.

Cutting time: 3. An interrupted steel cutting test was conducted under the following conditions. In the former continuous steel high-speed cutting test, the rake face wear depth and flank wear width of the cutting edge were measured, and in the interrupted steel cutting test, 6 pieces were measured. It was measured how many of the test cutting edges had defects.

The results of these measurements are shown in Table 1. Table 1 also shows the condition of the polished surface of the alloy structure.

From the results shown in Table 1, it is clear that Alloys 1 to 10 of the present invention exhibit superior wear resistance in continuous cutting and superior impact resistance in interrupted cutting, compared to conventional alloys. It is.

On the other hand, it can be seen that Comparative Alloys 1 to 8 are inferior in at least one of the above characteristics.

As mentioned above, the WC-based sintered hard alloy of the present invention has extremely excellent heat resistance, oxidation resistance, welding resistance, plastic deformation resistance, and impact resistance, so it is suitable for cutting high-hardness materials. It not only shows excellent cutting performance when applied to high-speed cutting and even heavy-duty cutting, but also when used in hot drawing dies and hot rolling rolls that require heat resistance and impact resistance. Because it exhibits excellent properties and is also excellent in corrosion resistance, it can be used in a wide range of applications, such as being suitable for manufacturing corrosion-resistant and wear-resistant parts, and it exhibits excellent effects in each field of use.

Claims (1)

[Claims] 1. Carbonates, nitrides, and carbonitrides of Ti, in which the molar ratio of oxygen to the total amount of oxygen and either or both of carbon and nitrogen is 0.2 or less. one of the group consisting of Ti, and one or more carbonates, nitrides, and carbonitoxides of metals in groups 4a, 5a, and 6a of the periodic table excluding Ti. Species or two or more: 1 to 50%, One or two or more of iron group metals: 5 to 30%, 4a, 5a of the periodic table excluding tungsten carbide
. and one or more of group 6a metal carbides, nitrides, and carbonitrides: 1 to 50%, tungsten carbide and unavoidable impurities: the remainder (volume %). A tungsten carbide-based sintered hard alloy containing oxygen. 2 Ti carbonate, nitride oxide, and carbonitride oxide, and Ti, in which the molar ratio of oxygen to the total amount of oxygen and either or both of carbon and nitrogen is 0.2 or less; 4a, 5a, and 6 of the periodic table excluding Ti
One or more of the group consisting of carbonates, nitride oxides, and carbonitrides of one or more group a metals: 1 to 50%, one of the iron group metals species or two or more and one or more of the chromium group metals: 5 to 30%, 4a and 5a of the periodic table excluding tungsten carbide. and one or more of group 6a metal carbides, nitrides, and carbonitrides: 1 to 50%, tungsten carbide and unavoidable impurities: the remainder (volume %). A tungsten carbide-based sintered hard alloy containing oxygen.