JPS6383241A - Tool cermet and its production - Google Patents

Abstract

PURPOSE:To manufacture a tool cermet excellent in hardness, deflectivity, and toughness, by mixing a solid solution having a specific composition consisting of TiCN and one or more elements among W, Wo, Ta, and Nb, WC, and iron group metals in a specific ratio and then by subjecting the resulting mixture to compacting and then to heating and sintering. CONSTITUTION:The solid solution in which 5-60% of the quantity corresponding to that of Ti atoms in TiCN is substituted by one or more components among W, Mo, Ta and Nb is formed. The above solid solution (54-92wt%) as a hard component, 5-40% WC as an independent addition agent, and 3-6% iron group metals to be a binding phase are mixed, to which 3-4% VC is further added independently, if necessary. The resulting mixture is subjected to press compacting with the addition of prescribed compacting auxiliaries. Subsequently, the above green compact is sintered in vacuum, etc. In this way, the tool cermet in which the hard phase of three-layer structure consisting of a central core, an intermediate layer in the outside periphery of the core, and a peripheral structure in the outermost periphery is bound by means of the binding phase composed principally of iron group metals together with the independent addition agent and which has high hardness and excellent toughness can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a cermet for tools that has high hardness and excellent toughness, and a method for manufacturing the same.

"Prior Art" TiN-TiC cermets are widely used in cutting tools.

TiN-TiC cermets tend to have uneven sintering and voids during sintering, which reduces their strength. The one that takes into account the amount of Go and
It is disclosed in Japanese Patent No.-35259.

In addition, it was reported in Japanese Patent Publication No. 58-58420 that it is not possible to improve both the wear resistance and chipping resistance of TiN-TiC cermets, which are inversely proportional to each other, simply by adding various metals or improving the binder phase. discloses the following method. Due to specific sintering conditions, the titanium carbonitride phase has an asymmetrical X-ray diffraction image, and the width of the background on the low angle side and the width of the background on the high angle side centering on the highest peak position of the X-ray diffraction image. It has an appropriate width and improves both wear resistance and chipping resistance.

``Problems to be solved by the invention'' Conventionally, TiN-TiC cermets have been improved by adding appropriate amounts of various metals to improve their strength, but reducing the hardness leads to a decrease in toughness; As a result, both properties could not be sufficiently matched.

Therefore, as a result of testing by changing the means of adding various metals during the production of TiN-TiC cermets, the present inventors found that by adding WC alone, separately from the solid solution with titanium carbonitride, the hardness of the cermet could be improved. The phase is a triple phase consisting of a core at the center, an intermediate phase at the outer periphery, and a peripheral structure at the outer periphery, and each particle of this triple phase exists in small amounts independently in the skeleton. Knew. It was discovered that hardness and toughness can be improved by blending the structure with such a skeleton state, and that wear resistance and surface roughness of the cut surface can be improved by adding VC alone. completed.

"Means for Solving the Problems" The first invention provides carbonitride (5 to 60% of the Ti atom equivalent of titanium is made of one or more of W, Mo, Ta, and Nb). A cermet for tools in which the hard phase substituted with the component consists of a core mainly composed of Ti, an intermediate layer around the core consisting of W and Ti components, and a peripheral structure mainly composed of W around the outer periphery of the intermediate layer. In the structure of cermet, each particle of the hard phase consisting of three phases exists independently in a skeleton.

In the above cermet, there is an intermediate phase (white phase) on the outer periphery of the core.
It is important that the hard phase particles are formed and that the hard phase particles exist singly in forming the skeleton, thereby improving both the height and toughness of the cermet.

The second invention is a method for manufacturing a cermet for tools, in which 5 to Bout% of titanium carbonitride equivalent to Ti atoms is mixed with W, Mo,
Solid solution 54-I which becomes a hard phase substituted with one or more components among Ta and Nb] 2wt%, WC5-40wt% as a single additive, and 3-8wt% ferrous metal as a binder phase. % and then heated and sintered after molding to produce a cermet.

Incidentally, VC may be added alone in an amount of 2 to 4 wt% before mixing each component.

5 to 80 wt% of the Ti atom equivalent of titanium carbonitride is W,
The reason why the solid solution substituted with one or more components among Mo, Ta, and Nb was 54 to 92 wt% was 54
This is because if it is less than 92 wt%, the required hardness and wear resistance as a cutting tool cannot be expected, and if it exceeds 92 wt%, it will lead to a decrease in toughness.

The reason why the amount of WC as a single additive is limited to 5 to 40 wt% is that when 5 at% is added alone without swirling, the amount of skeleton is too large and the toughness is too low. This is because when added alone in an amount exceeding 40 wt%, hardness increases and toughness decreases.

Furthermore, the reason for setting the amount of VC as a single additive to 2 to 4 wt% is that adding 2 wt% without swirling does not have the effect, and adding more than 4 wt% reduces crack resistance and reduces chipping of the cutting edge. This is because it is more likely to occur and is inconvenient.

The reason for setting the ferrous metal content as a binder to 3 to 8 wt% is because if it is less than 3 wt%, the binder will be insufficient and the wear resistance and chipping resistance will decrease, and if it is contained in excess of E1 wt%, the hardness will decrease. Because it does.

"Example" Components that become the hard phase of cermet (Ti, W,
Mo, Dina, Nb) A solid solution of CN was used. The amount of each metal in this solid solution is Ti > W > Ta > N
The relationship is o>Nb, and Ti is 21 to 87% of the total metal content.
The content was adjusted to 4wt%.

To this solid solution, WC was added alone, Go+Ni as a binder phase was added, and the mixture was mixed in a ball mill (se I(r)) in denatured alcohol. 92 wt%, single addition ty) W C 5 to 40 wt%, Go+Ni 3 to 8
Although it is preferable to use wt%, samples with other components were also prepared and the characteristics of the cermet were measured.

Approximately 2 wt % of paraffin was added to the above mixture as a molding aid, dried, passed through a sieve, and press-molded. Next, it was sintered at 1350 to 1500'0 in vacuum or N2 gas to form a cermet.

The hardness (Ilv
), transverse rupture strength (kg/11 m2), and crack resistance (kg/layer) representing toughness were measured and shown in Table 1.

In Table 1, cermets were produced in the same manner by adding VC alone to the above composition, and the same properties as above were measured and shown.

(Margin) Table 1 (wt%) From Table 1, samples E, F, engineering, M, N, and Q are as follows:
Hardness, transverse rupture strength and crack resistance are generally good and desirable.

A desirable sample cermet component is titanium carbonitride T.
5 to 80 wt% of i atom equivalent to W, Mo, Ta, Nb
A solid solution substituted with one or more of the following components is 54
It is within the range of ~92 wt%. In addition, the amount of WC as a single additive in a desirable sample is 5 to 40 wt%, and the amount of ferrous metal as a binder phase is 3 to B a
t%.

Further, a desirable sample in which VC is added alone has a WC amount of 2 to 4 wt%.

Next, in the above example, the amount of WC added alone was set at 15 wt% (
WC amount in solid solution is 15wt%), CO + old amount is 5wt%
% (WC30wt% in alloy)
A microscopic photograph (3000x) of the structure is shown in Fig. 1. Furthermore, for comparison, a microscopic structure photograph (30
00x) is shown in Figure 2. From Figure 1, in the case where WC is added alone, an intermediate layer is formed between the core of the hard phase particle and the surrounding structure, resulting in a triple phase, and each particle of this triple phase forms a skeleton. It exists even more independently within. In addition, when we did a component test, we found that the core of the triple phase is T.
i is the main component, the intermediate layer is W and Ti (W≧Ti), and the surrounding tissue is composed of W as the main component.

It is believed that this intermediate layer improves the hardness, transverse rupture strength, and toughness of the cermet. In FIG. 2 of the comparative example, it can be seen that no intermediate layer is formed around the outer periphery of the core of the hard phase, and that most of the hard phase forms a skeleton.

Next, the cermets (Samples A, D,
Cutting test with E, H1 machining, J) [Work material, SKD, cutting speed; 100 m/win, feed; 0.1
5 mm/rev, depth of cut: 1.5 mm], and the amount of friction over time was measured and shown in Figure 3.

From FIG. 3, it can be seen that samples D, E, and I are desirable because they have a small amount of wear, while samples A, H, and J are not desirable.

Similarly to the above, a cutting test was carried out by changing the work material, and the results are shown in FIG. The samples were A, D, F, H1 work, and J, and the work material, SCM, cutting speed: 200 m/win, feed: 0.15 mw/rev, and depth of cut: 3 mm.

From FIG. 4, it can be seen that samples D, F, ■, and J are desirable because they have a small amount of wear, while samples A and H are undesirable.

Similarly to the above, a cutting test was carried out by changing the workpiece materials, and the results are shown in FIG. Samples are A, D, E, H, I
, J, work material: FCD, cutting speed: 150m/■
in, feed; 0.15 ■ intestine/rema, incision; 1
．． It was set as a 5m layer.

From FIG. 5, it can be seen that samples D, E, and I are desirable because they have a small amount of wear, while samples A, H, and J are not desirable.

Next, the cermet of the above example was used for cutting, and the roughness of the cut surface due to cutting over time was measured, and the results are shown in FIG. The samples are D, L, M, N, 0, and the work material is DAC1.
Cutting speed: 100 m/sin, feed: 0.1
5 seals/rema, incision; 1.5+s layer.

From FIG. 6, it can be seen that samples D, L, M, and N have a small surface roughness, which is desirable, but a surface roughness of 0 is not desirable.

Through the above four types of cutting tests, samples E, F, and ■ have desirable machinability, but these have the hardness shown in Table 1,
This corresponds to the fact that transverse rupture strength and crack resistance are desirable.

"Effects of the Invention" The present invention involves adding and mixing a single WC to a titanium carbonitride-based hard phase material and an iron group metal binder phase material as cermet materials, and then sintering the mixture to produce a cermet. According to
The hard phase has a three-layer structure consisting of a central core, an intermediate phase on its outer periphery, and a surrounding tissue on its outer periphery. Since the hard phase particles consisting of three layers exist independently in the skeleton, the hardness, transverse rupture strength, and toughness of the cermet are all improved.

[Brief explanation of the drawing]

Figure 1 is a micrograph of the cermet of the present invention, Figure 2.
The figure is a microscopic structure photograph of a cermet of a comparative example, Section 3.4.
Figure 5.6 is a graph showing the results of cutting tests using cermets.

Claims (3)

[Claims] (1) 5 to 60% of the Ti atom equivalent of titanium carbonitride is replaced with W.
, Mo, Ta, and Nb, the hard phase is composed of a central core, an intermediate layer around the outer periphery of the core, and a peripheral structure at the outermost periphery, and the hard phase has a three-layer structure. A cermet for tools that is bonded with a binder phase mainly composed of ferrous metals. (2) 5 to 60% of the hard phase component equivalent to Ti atoms in titanium carbonitride is one of W, Mo, Ta, and Nb.
Solid solution substituted with species or two or more components 54-92wt
%, 5 to 40 wt % of WC as a single additive, and 3 to 6 wt % of ferrous metal as a binder phase, and then heated and sintered after molding. (3) The method for manufacturing a cermet for tools according to claim 2, wherein 2 to 4 wt% of VC is further added singly to the total amount.