JPS5929094B2 - sintered hard alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sintered hard alloy containing Ti as a main component, which has significantly improved cutting properties, and further contains Cu as a bonding metal.

Conventionally known titanium carbide-based hard alloys are not only inexpensive raw materials, but also have low oxidation resistance at high temperatures and low chemical affinity with metals, so they are used as cutting tools with excellent wear resistance, especially for high-speed cutting of steel. It is mainly used for the following four
Because it has two drawbacks, its range of use has been extremely limited.

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 during 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 increases, so the TiC-based alloy will significantly deform the cutting edge and will no longer be able to withstand cutting.

This is probably the main reason why TiC-based alloys are used only for 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 are changes in depth of cut, feed, etc., unsteady heat generation and loads, such as profile cutting and black scale cutting.

Various efforts have been made in the past to improve the three main drawbacks mentioned above.

The most recent of these results is conventional TiC
By adding nitrides to a base cermet alloy, a sintered hard alloy with a fine-grained structure is obtained, and the toughness and resistance to plastic deformation at high temperatures are improved.

In these alloys, the above-mentioned drawbacks can be alleviated to some extent.

However, there is a fourth drawback.

Although it has improved the above-mentioned drawbacks, the conventional T
iC-based alloys have a layer on the surface that is harder than the inside, resulting in an uneven structure on the surface and inside, and the surface is brittle and easily chipped when cut with tools that do not grind the surface. It is that you are.

The object of the present invention is to improve upon such known drawbacks, and in particular to provide a sintered hard alloy that has a uniform surface and internal structure, has a fine-grained structure, and has improved heat fatigue toughness.

The above object of the present invention is to provide a hard alloy for cutting tools having a hard phase and a bonding metal phase, comprising a hard phase of 97 to 75 weight percent and a bonding metal of 3 to 25 weight percent; The metal component to be mainly formed is a composition containing Ti as a main component and at least one of W or Mo in a proportion of 5 to 40% by weight, and optionally containing Ta and/or Nb in a proportion of 3 to 40% by weight, and mainly forms the hard phase. The non-metallic component of the hard phase is composed of carbonitride, of which 5 to 40% by weight is nitrogen, and the binding metal that binds the hard phase is one or more iron group metals. This is achieved by a sintered hard alloy characterized by containing 1 to 60% by weight of Cu in the metal, especially in the bonding metal.

(All figures below indicate weight %.

) The greatest feature of the present invention lies in the hard phase and the binder phase.

The metal component for forming the hard phase is mainly Ti (20% or more), 5 to 40% of at least one of W or Mo, and the nitrogen content of the non-metallic components is carbon and carbon. By setting the amount of nitrogen to 5 to 40% of the total amount, toughness, particularly thermal fatigue toughness, can be significantly improved without significantly reducing wear resistance.

Furthermore, in some cases, adding 3 to 40% of Ta (or Nb) can provide even better effects.

This is because Ta significantly improves the thermal fatigue resistance, which is the third drawback of existing cermets.

The reason for this is not clear, but since mechanical strength is significantly improved by the addition of Ta, it can be inferred that Ta contributes in some way to improving the thermal properties of the hard phase of the pre-alloy system and the bonding metal phase. .

It is also possible that it improves thermal properties such as thermal conductivity.

The reason why Ta is set to be less than 40% is because if it is more than this in the metal component of the hard phase, it is expensive and the hardness decreases, making it impractical. This is because smaller amounts have no substantial effect.

Further, from the viewpoint of improving toughness, it is preferable to add part or all of Ta in the form of TaN.

In addition, since Nb is the same family as Ta and has very similar properties, T
A part of a may be replaced with Nb.

In addition, W or Mo has the effect of improving the wettability of the hard phase of the alloy and the bonding metal phase, making the structure finer, and improving mechanical toughness, but if it exceeds 40%, the wear resistance may decrease. However, it is necessary to limit the amount to 5 to 40% without losing practicality, and because if it is less than 5%, the effect is substantially lost.

Further, it is not harmful even if small amounts of other IVa, Va, and VIa group high melting point metals are included.

Next, we will discuss limitations on the nonmetallic components of the hard phase.

If the non-metallic component is added in an atomic ratio exceeding 1.0 times the metal component of the hard phase, free graphite will be added to the alloy.
If it is less than twice that, a embrittling phase (for example, M6 (C, M) phase) will appear and the alloy will become brittle.

Therefore, the amount of the nonmetallic component is set to be 0.8 to 1.0 times the amount of the metal component in the hard phase in terms of atomic ratio.

In addition, the nitrogen component works with the W and Mo components to refine the structure of the titanium carbonitride-based sintered hard alloy and contributes to improving the toughness and plastic deformation resistance at high temperatures. If the content exceeds 40% of the total amount, the sinterability will deteriorate and practicality will be lost, and if it is less than 5%, there will be no substantial effect.

Therefore, 5-40% is required.

Furthermore, in order to maintain good wear resistance of the titanium carbide-based or titanium carbonitride-based sintered hard alloy, it is necessary to make Ti the main component of the metal components of the hard phase.

When the main component is Ti, it means that Ti accounts for the main component in terms of mole fraction.If defined in terms of weight, Ti must account for 20% or more of the metal components constituting the hard phase. There is.

The reason for blending one or two types of iron group metals is to improve toughness, and if the amount is less than 3%, this purpose cannot be achieved, and 25%
If it exceeds this, the hardness will drop significantly and practicality will be lost.

Next, the effect of adding Cu as a binding metal is important;
It has been found that the fourth drawback of existing cermets, which is that they have a hard layer on their surface and are therefore prone to chipping, can be significantly improved.

The reason for this is not clear, but since the addition of Cu makes the surface and interior uniform as shown in Figure 1, it is presumed that it has the effect of stabilizing the bonded metal phase.

It is also possible that the structure becomes even finer, improving thermal properties such as thermal conductivity.

The reason why the amount of Cu is set to 1 or more is that it is not effective if it is less than that.
The reason why the content is set at 60% or less is that if it exceeds 60%, sinterability deteriorates.

In addition, it is preferably 5 to 50 units. The alloy of the present invention is Ti,
A hard phase containing - or both of W or Mo, Ta, N, C, and Ni in addition to Cu.

It is an alloy with a structure consisting mainly of a binder metal phase such as Co and no precipitated WC phase, but like conventional cemented carbide, some of the raw materials used in the form of WC2TaC2M02C2TiC etc. Diffuses into the bound metal phase.

Therefore, although Ti, Ta, W, Mo, N, and C are used to form a hard phase (mainly with the B1 crystal structure), there are also parts that do not participate in the formation of the hard phase, so these are used mainly to form the hard phase. These are expressed in the claims as metallic components and non-metallic components for forming.

The present invention will be explained in more detail with reference to Examples below.

Example 1 Commercially available Ti (expressed as TiC for convenience, originally TiC1-x (where X is O or 1 or less), hereinafter the same) powder with an average particle size of 1μ (total carbon content 19.70%, free carbon content 0. 35
%) and TiN powder of approximately the same particle size (nitrogen content 20.25%).
), WC powder (total carbon content 6.23 cm, free carbon content 0.1
1%), and MO2C powder (total carbon content 5.89%, free carbon content 0.03%), and Co
Powder, Ni powder under 287 mesh, and Cu powder under 100 mesh were mixed according to the composition shown in Table 1, and acetone was added to this using a TiCNt Mo ball with a diameter of 10 Wt 11 L using an 18-8 stainless steel lined pot. The mixture was mixed in a wet ball mill for 96 hours.

Add 3 parts of camphor to this mixed powder and add 2t/Crj
! Embossed with L.

This stamped body was heated at 1450°C under a vacuum of 10-3 Hg for 6 hours.
An alloy was created by firing for 0 minutes.

Table 2 shows the mechanical properties of the obtained alloy, and FIG. 1 shows the hardness distribution from the surface to the inside.

Table 3 shows the results of a cutting test using a tool that does not grind the surface.

Test conditions Wear resistance test: Work material SCM3 ((IHs38±2 diameter 150mmV=200 m/min, d=1
．． 5mm, f=0.36mm/rev, T=
10m1n heat fatigue toughness test; Rigid material (with ■ type groove) SCM3(El)Hs 38±2 diameter 70mvt.

V = 150 m/min, d = 1.5 mm,
f = 0.59mi/rev.

From the above results, it is clear that the alloy of the present invention is superior in various properties.

Example 2 Commercially available Ti (m powder) with an average particle size of 1μ (total carbon content 19.70
%, free carbon content 0.35 clO) and Ti of the same particle size
N powder (nitrogen content 20.25%), WC powder (total carbon content 6
．． 23%, free carbon content 0.11%), and Mo2C powder (total carbon content 5.89%, free carbon content 0.03%), Co powder under 100 mesh, Ni powder under 287 mesh, 100 mesh Lower Cu powder, particle size 1.3μ
TaNff1 powder (nitrogen content 6.8%), particle size 12μ T
aC powder (total carbon content 6.20%, free carbon content 0.02%
) and NbC powder with a particle size of 2.5μ (total carbon content 11.0
%, free carbon content 0.02%), and acetone was added using a Tie-Ni-Mo ball with a diameter of ioam in an 18-8 stainless steel lined pot, and wet-processed. The mixture was mixed in a ball mill for 96 hours.

Add 3% camphor to this mixed powder and add 2t/cI
? Embossed with L.

This stamped body was vacuumed at 1450 mrrtHg.
An alloy was prepared by firing at ℃ for 60 minutes.

The mechanical property values of the obtained alloy are shown in Table 5, and the hardness distribution 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.

Test conditions Wear resistance test; Work material SCM3HH838±2 diameter 2
00mrILV=200m/min, d=1.5
mm, f=0.36mm1 rev, T=0m
1n Heat fatigue toughness test; Work material (with type groove) SCM3 (
H) Hs38±2 diameter 1100Wt, V-150m/
min, d=1.5mm, f=0.59mr
tt/rev, T-until chipped From the results shown in Figure 2 and Table 6, the alloy of the present invention, which contains Cu in the bonding metal and Ta or Nb in the hard phase, is uniform on the surface and inside. , it is clear that it has extremely excellent thermal fatigue toughness.

[Brief explanation of the drawing]

FIGS. 1 and 2 are graphs showing changes in hardness from the surface to the inside of the alloy of the present invention and the comparative alloy.

Claims (1)

[Scope of Claims] 1. A hard phase consisting of a metal component and a non-metal component, and a bonding metal containing an iron group metal and Cu that bind the hard phase, and the metal component mainly forming the hard phase is W
and Mo, or both, and Ti, and the nonmetallic component consists of N and C, and the total amount of the nonmetallic component is equal to the total amount of the metal component for mainly forming the hard phase in terms of atomic ratio. 0.8 to 1.0 times, and the amount of N in the nonmetallic component is 5 to 40% by weight, and the hard phase consists of carbonitride and does not have a phase consisting only of WC. The whole alloy is 10
When the weight ratio is 0, the bonding metal in this is 3 to 2
5% by weight, the bonded metal contains 1 to 60% by weight of Cu, the hard phase contains 20% by weight or more of Ti, and 5 to 40% by weight of W and/or Mo. Sintered hard alloy. 2. A hard phase consisting of a metal component and a non-metal component, and a bonding metal containing an iron group metal and Cu that bind the hard phase, and the metal component mainly forming the hard phase is W.
and Mo, or both, and Ti, and the nonmetallic component consists of N and C, and the total amount of the nonmetallic component is the total amount of the metal component to mainly form the hard phase in terms of atomic ratio. and the amount of N in the non-metal component is 5 to 40% by weight, the hard phase is made of carbonitride and does not have a phase consisting only of WC, This entire alloy is 1
00 weight ratio, the bonding metal in this is 3~
25% by weight, Cu is contained in the bond metal by 1 to 60% by weight, Ti is contained in the hard phase by 20% by weight or more, W and Mo
- or both of 5 to 40 weight coefficients, Ta and/or N
A sintered hard alloy containing 3 to 40% b by weight.