JPS6034618B2 - Sintered hard alloy and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the internal structure and sintering method of a sintered hard alloy containing Ti as a main component.

Conventionally known titanium carbide-based hard metals are not only inexpensive raw materials, but also have low oxidation resistance at high temperatures and low chemical affinity with metals, making them useful as cutting tools with excellent wear resistance, especially for high-speed cutting of steel. Although it has been used, its range of use has been extremely limited due to the following three drawbacks.

The first reason is that it has poor toughness and is prone to chipping.

For example, it is known from experience that TIC-based alloys are more likely to chip than conventional WC-based alloys when used in places where they are subjected to impact forces such as interrupted cutting, or when machine tools have low rigidity. . The second reason why the use of TIC-based alloys is limited is that the cutting edge deforms significantly under high temperature and high pressure.

In actual heavy-duty cutting, the temperature of the cutting edge becomes high, so in TIC-based alloys, the cutting edge becomes significantly deformed and cannot withstand cutting. This is probably the main application of iC-based alloys, which are limited to light cutting. Furthermore, when cutting high-hardness materials, the temperature at the cutting edge increases significantly, so TIC-based alloys are not suitable in this case, and this is also a factor that limits the range of use of this alloy.

The third drawback of TIC-based alloys is that their thermal fatigue resistance is inferior to that of WC-based alloys.

Due to this drawback, TIC-based alloys cannot yet be used in sites where there is unsteady heat generation and load, such as profile cutting and black scale cutting, where the depth of cut, feed, etc. change.
Various efforts have been made in the past to improve the three main drawbacks mentioned above. The most recent of these achievements is the addition of TIN to a conventional TIC-based alloy to obtain a crystallized hard alloy with a fine grain structure, which improves hardness and plastic deformation resistance at high temperatures. In these alloys, the first and second drawbacks can be alleviated to some extent.
However, we have discovered that there is a fourth drawback to the TIC group.

Although this has improved the above-mentioned drawbacks, TI
In C-based alloys, a metal phase exudes to the surface, and at the same time there is a layer harder than the inside directly below it, which is not seen in the case of WC-based cemented carbide, and the surface and inside become unconventional. It has a uniform structure, and has the disadvantage that if it is cut using a tool that does not grind the surface, the surface is brittle and easily chipped. The object of the present invention is to improve such drawbacks, and particularly to provide a hard alloy having a uniform surface and internal structure.

The sintered hard alloy of the present invention consists of 97 to 75% by weight of a hard phase and 3 to 25% by weight of a bonding metal mainly composed of iron group metals, and the hard phase is composed of a group a metal such as Wa, Va, etc. ,
The non-metallic component mainly forming the hard phase consists of carbon, nitrogen and/or oxygen.

Among the above hard phases, cases where Va group metal is not included and cases where Wa group metal is not included.
From 0.01% to 30 mol% of the metal is V of the Va group metal.
, Nb, and Ta.

Regarding the limitations of the alloy of the present invention, carbon as a non-metallic component,
When the molar fractions of nitrogen and oxygen are expressed as u, v, w, v
If it is 0.045 or less, the effect of nitrogen to refine the alloy and the effect of stably containing oxygen is lost, and if it is 0.36 or more, the agglomeration property deteriorates.

Moreover, when w is 0.005 or less, there is no effect of oxygen inclusion, and when it is 0.20 or more, the silk-sintering property becomes poor. metal (Group Wa metal + Group Va metal +
(Wa group metal) The number of bonds in gram atoms of carbon, nitrogen and oxygen per gram atom, 0.80, 1.
It fluctuates between 05 and 05. If it is less than 0.80, there is an arm phase and it is not suitable, and if it is more than 1.0, free carbon is present, but 1
．． There are no performance problems up to 05.

In addition to iron group metals, the bonding metals include AI, Cu, and Ag.
, Si, B containing 0.2 to 25 wt% of one or more types, but replacing the iron group metals Co, Ni, and Fe to 5 M%
The effects of the invention can be maintained by adding the following features. In other words, the addition of mountains has the effect of contributing to strengthening the binder phase, and Cu
Adding suppresses grain growth and improves thermal conductivity.

It also works to make the surface and internal structure uniform. Addition of Ag improves wettability and can be expected to improve thermal conductivity. Si and B also contribute to improving the silk-sintering property. In producing a hard alloy for cutting tools having the above-mentioned hard phase and bonding metal phase, the fourth disadvantage mentioned above can be solved by obtaining an alloy with a structure in which the internal structural heterogeneity is eliminated or reduced. Remove.

Furthermore, in alloys with such a homogeneous structure, since the cause of non-uniformity is surface deoxidation, theoretically the oxygen potential in the furnace atmosphere during the cooling process in the sintering process is higher than that inside the sintered body. In practice, part or all of the CO gas partial pressure in the cooling process is reduced by the CO gas partial pressure in the heating process and the liquid phase sintering process.
This is most effectively achieved by maintaining the partial pressure higher than the O gas partial pressure. Here, the most preferred range of CO gas partial pressure is 0.01 to 300 Ton.

The greatest feature of the present invention is that part or all of the cooling process
The purpose is to maintain the O gas partial pressure higher than the CO gas partial pressure during the temperature raising process and the liquid phase formation process.

Conventional cermet sintering methods usually involve sintering the entire process under vacuum, or sintering part or all of the process in 1 atm hydrogen; however, these existing sintering methods In the latter alloy, a bond metal phase oozes out on the surface, and a hard and brittle layer exists immediately below the leaching phase in which the ratio of the bond metal phase to the hard layer is smaller than the inside, and the surface and the inside are It has become an uneven organization.

Figure 1A shows a non-uniform structure.

The effect of CO gas is important here, and by making the CO gas partial pressure during part or all of the cooling process higher than the CO gas partial pressure during the heating process and liquid phase sintering process, the bonded metal to the surface can be It has been found that phase leaching can be suppressed and the metal binder phase can be uniformly dispersed.

Figure 1 shows a uniform tissue in the mouth. The reason for this is not clear, but if a CO bait atmosphere is created during the temperature raising process and/or liquid phase sintering process, the CO saddles will diffuse into the pores or through the metal bonding phase, and the oxygen concentration on the surface and inside will decrease. Although averaged, 10-3 to 10-4 willow H during the cooling process
When placed in a vacuum atmosphere of g, oxygen at the surface is removed, the oxygen concentration becomes lower than the inside, and the metal bond phase seeps out to the surface. If part or all of the Cogas partial pressure during the cooling process is made into an atmosphere higher than the Cogas partial pressure during the heating process and the liquid phase sintering process, the oxygen concentration at the surface will be higher than the inside, and the oxygen concentration on the surface will increase. It is thought that this prevents the metal binder phase from seeping out and at the same time uniformly disperses the metal binder phase. The hardness of the sintered body from 0.005 to 0.2 from the surface is 1. The hardness is 1.02 times or less than the hardness of the bow.
This is because if it is twice or more, the surface is likely to be chipped if it is cut without being ground.

In the conventional Akatsuki Aya method, the hardness from the surface to the 0.005 to 0.2 side is 1. The hardness of the vowel is 1.04 to 1.0. Note that this phenomenon is not limited to cases containing Ti, but is particularly applicable to group A metals such as Wa, Va, and B-type solid oxides in which the nonmetallic components are carbon and/or a small amount of oxygen. This is a common phenomenon.

Naturally, the feature of the present invention is to obtain an effect by maintaining the oxygen potential during cooling at a value higher than the oxygen potential inside the alloy, so in combination with CO gas, an inert gas (He, ~, day 2 etc.) may also be used. In this case, it is necessary to maintain the CO gas at a predetermined partial pressure. Also, some &○ and C02 gas may coexist. The present invention will be explained in more detail with reference to Examples below. Example 1 Commercially available TIC with an average particle size of 1〆 [For convenience, the main button is indicated as TIC, 1× (however, x is 0 or 1 or less) and the following is the same]
Powder (total carbon content 19.70%, free carbon content 0.35%)
TIN powder (nitrogen content 20.25%) with approximately the same particle size as W
C powder (total carbon content 6.23%, free carbon content 0.11%)
and Mo2C powder (total carbon content 5.89%, free carbon content 0
．． 03) and Co powder under 100 mesh, 287
The Ni powder under the mesh was blended with the composition shown in Table 1, and acetone was added using a TIC-Ni-Mo ball with a diameter of 1 inch in an 18-8 stainless steel lined pot, and then processed in a wet ball mill. Mixed for 9 hours.

3% camphor was added to this mixed powder, and it was embossed with Genu/c liquid. After firing this stamped body for 6 minutes at 138,000 in Hg vacuum on the 10-3 to 10-4 side, the CO gas partial pressure during cooling was 5 Tom, the gas flow rate was 0.5 m/min, and 800 o
An alloy was prepared by flowing the mixture to o. The mechanical property values of the obtained alloy are shown in Table 2, the hardness distribution from the surface to the inside is shown in FIG. 2, and the amount of metal binder phase and oxygen amount from the surface to the inside is shown in FIG. Table 3 shows the results of a cutting test using a tool that does not grind the surface.

Table 1 (grandson) Table 2 Table 3 Test conditions Intermittent test; Work material SCM3 (H) Hs38±2 diameter 10
Wear resistance test; Work material SCM3 (H) Hs38±2 diameter 2
00 side V = 20 h/min, d = 1.5 skin f 2 0.36 legs/rev, T 2 dishes h; n From the cutting test results shown in Table 3, the alloy of the present invention is extremely excellent in chipping resistance. It can also be seen that it has excellent wear resistance.

Example 2 Commercially available TIC with an average particle size of 1 French [For convenience, it is expressed as TIC, originally TIC, 1× (however, x is 0 or 1 or less) and the same applies below]
Powder (total carbon content 19.70%, free carbon content 0.35%)
TIN powder (nitrogen content 20.25%) with approximately the same particle size as W
C powder (total carbon content 6.23%, free carbon content 0.11%)
and Mo2C powder (total carbon content 5.89%, free carbon content 0
．． 03%) and Co powder under 100 mesh, 28
7 mesh or lower Ni powder according to the composition shown in Table 4, acetone was added using a 18-8 stainless steel lined pot using a TIC-Ni-Mo ball with a diameter of 10 bars, and a wet ball mill was used. The songs were mixed for 9 hours.

3% camphor was added to this mixed powder, and it was embossed with a public/memory press. When this embossing body is heated up, it is heated to 120,000 to 1,380.
The CO gas partial pressure was set to 5 Torr and the gas flow rate was set to 0.5 so/min until noon C. After that, after baking at 138,000 for 60 minutes under a vacuum of Hg on the 10-3 to 10-4 side, the CO gas partial pressure was 15 Ton during cooling. Gas flow rate 0.5 so/min, 800℃
The alloy was prepared by flowing up to . The mechanical property values of the obtained alloy are shown in Table 5, the hardness distribution from the surface to the inside is shown in FIG. 2, and the amount of metal binder phase and oxygen amount from the surface to the inside is shown in FIG. Table 6 shows the results of a cutting test using a tool that does not grind the surface.

-Table 4 (%) Table 5 Table 6 Test conditions Intermittent test; Work material SCM3 (H) Hs38±2 diameter 10
Wear resistance test: Work material SCM3 (H) Hs38±2 diameter 2
0㎇嬬V: 20㎇h/min, d = 1.5 ribs f = 0.36 side/rev, T = 1㎇hin From the cutting test results shown in Table 6, the alloy of the present invention is extremely excellent in chipping resistance. It can also be seen that it has excellent wear resistance.

Example 3 Commercially available TIC with an average particle size of 1 mm [For convenience, it is originally expressed as TIC, 1× (however, x is 0 or 1 or less) and the same applies below]
Powder (total carbon content 19.70%, free carbon content 0.35%)
TIC powder (nitrogen content 20.25%) with approximately the same particle size as T
i (C Misaki 0o.5) powder, WC powder (total carbon content 6.23
%, free carbon content 0.11%) and Mo powder (total carbon content 5.89%, free carbon content 0.03%), Co powder under 100 mesh, and Ni powder under 287 mesh were used. and mix it with the composition shown in Table 7, and apply it to a TI with a diameter of 1
Using a C-Ni-Mo pole, add acetone to the 18-8 stainless steel lined pot, and mill with a wet ball mill for 90 minutes.
Mixed song times.

3% of camphor was added to this mixed powder, and it was stamped with a public stamp. After firing this embossed body for 60 minutes under a vacuum of Hg on the 10-3 to 10-4 side with one spot pi○, it was heated to 800 qC at a CO gas partial pressure of orr and a gas flow rate of 0.5 min/min during cooling. An alloy was prepared by this method. Table 8 shows the mechanical properties of the obtained alloy. Figure 3 shows the hardness distribution from the surface to the inside, and Figure 6 shows the amount of metal binder phase and the amount of oxygen from the surface to the inside.

Table 9 shows the results of a cutting test using a tool that does not grind the surface.

Table 7 (Tsutomu) Tables 8 and 9 Test conditions Intermittent test; Work material SCM3 (H) Hs38±2 diameter 10
Wear resistance test; Work material SCM3 (H) Hs38±2 diameter 2
According to the results of the cutting test shown in Table 9, the alloy of the present invention has excellent chipping resistance. It can also be seen that the wear resistance is excellent.

Example 4 The alloy shown in Table 1 was produced using the same manufacturing method as in Example 1, and the mechanical properties and cutting test results of the obtained alloy were
This is what the table shows.

Table 10

[Brief explanation of the drawing]

Figure 1A is an explanatory diagram of the alloy structure created by the conventional sintering method.
On the surface, there is a phase a in which the metal binding phase has oozed out, and directly below it, a hardened phase b exists because the metal binding phase has decreased from the inside, resulting in a non-uniform structure. The opening in FIG. 1 has an alloy structure formed by the sintering method of the present invention and has a uniform structure. Figures 2 and 3 are charts showing changes in hardness from the surface to the inside of the invention alloy and comparative alloy, with A, G, and M representing the invention alloy and D, J, and P representing the comparison alloy. As can be seen from the graph, the hardness of the alloy of the present invention is approximately the same on both the surface and inside. Figures 4, 5, and 6 are charts showing changes in the amount of metal binder phase and oxygen content from the surface to the inside of the alloy of the present invention and the comparative alloy. As can be seen, the amount of metal binder phase in the alloy of the present invention is approximately the same from the surface to the inside. Also, the oxygen content is higher on the surface than inside. The amount of metallic binder phase in the comparative alloy is large on the surface and constant inside, but is small in the area immediately below the surface. Also, the oxygen content is higher inside than on the surface. External figure 2 figure soup 3 figure force 4 figure force 5 figure o 6 figure

Claims (1)

[Claims] 1 97-7 consisting of IVa, VIa, group metals and non-metal components
In an alloy in which 5% by weight of a hard phase is bonded with 3 to 25% by weight of a binding metal consisting mainly of iron group metals, the total composition of the hard phase is determined in atomic ratio {(Group IVa metal)a(Group VIa metal) )c}(CuNvOw)z (However, group IVa is Ti or T
Two or more metals containing i, group IVa is one or more selected from W, Mo, and Cr), and a+c=1,0.5 between a, c, u, v, and w. ≦a≦0.95, 0<c≦0
．． 5, there is a relationship of a≧c, u+v+w=1, and u, v,
The range of w, z, is 0.49≦u≦0.950.045≦
It is a sintered hard alloy with v≦0.36, 0.005≦w≦0.20, 0.80≦z≦1.05, and 0.00% from the surface of the sintered body.
The hardness from 5 to 0.2 mm is 0.02 times or less than the hardness at 1.0 mm from the surface, and the metal binder phase does not seep into the surface, and the hardness is 0.005 mm from the surface of the sintered body.
A sintered hard alloy characterized in that the oxygen content up to 0.2 mm is higher than the oxygen content 1 mm from the surface. 2 97-75 consisting of IVa, VIa group metals and non-metal components
In an alloy in which % by weight of a hard phase is bonded with 3 to 25% by weight of a binder metal consisting mainly of iron group metals, the total composition of the hard phase is expressed in atomic ratio as {(Group IVa metal) a(Group VIa metal) )c}(CuNvOw)z (However, group IVa is Ti or T
Two or more metals containing i, group IVa is one or more selected from W, Mo, and Cr), and a+c=1,0.5 between a, c, u, v, and w. ≦a≦0.95, 0<c≦0
．． 5, a≧c There is a relationship of u+v+w=1, and u, v,
The ranges of w and z are 0.49≦u≦0.95 0.045≦v≦0.36 0.005≦w≦0.20 0.80≦z≦1.05, and the sintered body The hardness from 0.005 to 0.2 mm from the surface is 1.02 times or less of the hardness from 1.0 mm from the surface, and no metal binder phase seeps into the surface;
and a method for producing a sintered hard alloy in which the oxygen content within 0.005 to 0.2 mm from the surface of the sintered body is higher than the oxygen content within 1 mm from the surface, in which all or part of the cooling process in the sintering process is performed. A method for producing a sintered hard alloy, characterized by maintaining the oxygen potential in the atmosphere at a temperature higher than the oxygen potential inside the alloy. 3 97-75 consisting of IVa, VIa group metals and non-metal components
In an alloy in which % by weight of a hard phase is bonded with 3 to 25% by weight of a binding metal consisting mainly of iron group metals, the total composition of the hard phase is expressed in atomic ratio {(Group IVa metal)a(Group VIa metal)
c}(CuNvOw)z (However, group IVa is Ti or Ti
group IVa is one or more selected from W, Mo, and Cr), and a+c=1 0.5≦a between a, c, u, v, and w. ≦0.95, 0<c≦0.5, a≧c, u+
There is a relationship of v+w=1, and the range of u, v, w, z, is
It is a sintered hard alloy with 0.49≦u≦0.950.045≦v≦0.36 0.005≦w≦0.20 0.80≦z≦1.05, and IVa group in the hard phase. metal 0
．． Va group metals V, Nb, T from 01% to 30 mol%
It is a sintered hard alloy substituted with one or more selected from a, and the hardness of the sintered body from 0.005 to 0.2 mm from the surface is 1.02 times or less than the hardness of 1 mm from the surface. The metal binder phase does not seep into the surface, and the oxygen content within 0.005 to 0.2 mm from the surface of the sintered body is higher than the oxygen content within 1 mm from the surface. Sintered hard alloy.