JPS6147899B2 - - Google Patents

Description

[Detailed description of the invention]

Carbides, nitrides, and carbonitrides are added to the so-called cemented carbide, which is composed of one or more hard phases of carbides, nitrides, and carbonitrides of Group A, A, and A group elements, and a binder phase whose main component is iron group metals. It is well known that coated cemented carbide tools coated with one or more compounds and/or oxides have particularly excellent wear resistance. Among others, TiC, Ti(CN),
It is known that a coated cemented carbide coated with 5 to 10 microns of one or more of TiN and Al ₂ O ₃ has a lifespan 2 to 10 times longer than conventional cemented carbide. However, these coated cemented carbides have various problems because they use base metals with iron group metals, especially Co, as a binder phase, and it cannot be said that they fully utilize the properties of the coated phase. It has been found that the characteristics required in tools can be broadly classified into two types. That is, toughness and wear resistance. As for toughness, it has been found through many years of research by the inventors that it can be further divided into two types. These are mechanical strength and thermal fatigue strength. The relationship between mechanical strength and wear resistance is contradictory in the above-mentioned cemented carbide, and if the iron group binding metal (in most cases Co) is increased and the mechanical strength is increased, the wear resistance will be decreased. I end up. Changes in thermal fatigue strength are quite complex. As the amount of Co increases, thermal fatigue strength increases.
If the amount of Co is too large, plastic deformation will occur, leading to a decrease in thermal fatigue strength. Therefore, there is naturally a limit to the improvement in thermal fatigue strength by increasing the amount of Co. On the other hand, in order to improve the efficiency of cutting tools, there is a need for tools with high thermal fatigue strength that can withstand heavy cutting with large depths of cut and feed, but in this case, particularly high toughness is required. Plastic deformation resistance is required, and current cemented carbide metals naturally have their limits. The present invention combines wear resistance and toughness by coating a base metal with a hard material that has plastic deformation resistance and thermal fatigue toughness at high temperatures that conventional cemented carbide cannot achieve. We propose a tool with excellent performance. In conventional cemented carbide with Co as a binder phase,
Due to the low softening temperature of the Co phase, plastic deformation resistance at high temperatures is already a problem under practical cutting conditions, and thermal fatigue toughness is also lower than the materials described below. Plastic deformation is also important in coated cemented carbide tools in another sense. The reason for this is that even if the cutting edge becomes hot during cutting and the cemented carbide metal is plastically deformed, the coating hard phase hardly deforms plastically in that temperature range, so it cannot follow the deformation of the metal and the coating breaks. Put it away. This causes chipping or peeling of the coating, shortening the tool life. Therefore, in order to prevent this, a high melting point metal such as W may be used as the bonding metal instead of the iron group metal. In fact, a few prototype alloys have been made based on this idea, and US _Pat. It has been proposed to produce the alloy by a so-called melting method in which an alloy of -W is heated to a temperature of around 2500°C, melted, and then cast. Although this alloy (hereinafter referred to as cast alloy) has much better wear resistance and plastic deformation resistance at high temperatures than the cemented carbide, it has the following drawbacks that prevent it from being widely used. I couldn't reach it. Firstly, toughness,
In particular, mechanical strength is extremely poor. Second, although it is an extremely difficult material to grind, it is made by casting, so products with complex shapes such as cemented carbide manufactured by powder metallurgy cannot be manufactured at low cost. Thirdly, due to the casting temperature, only alloys with low melting points near eutectic compositions can be obtained. There has also been a proposal for a (Ti,W)(C,N)-W casting alloy, but it has not been put to practical use for the same reason. Therefore, those skilled in the art can easily think that if these cast alloy compositions can be manufactured by powder metallurgy, the second and third drawbacks mentioned above can be overcome. However, although many attempts have been made to achieve this goal, no superior alloy has actually been created. The reason for this is that since the alloy with this composition is composed of carbides and high melting point metals such as Mo and W, its sinterability is extremely poor and sufficient strength cannot be obtained. The authors of this paper have conducted detailed research on these alloys, particularly the elements that form the hard phase, and have obtained surprising findings. In other words, they discovered that by introducing oxygen into the hard phase, which was conventionally thought to inhibit sintering in hard alloys, sinterability was significantly improved, and toughness was also improved. Based on this knowledge, the present invention proposes a high melting point metal binder hard alloy with excellent toughness as a tool that meets the recent demands for higher efficiency. The greatest feature of the present invention is that oxygen is actively introduced into the hard phase, but in this alloy, almost no oxygen is present outside of the hard phase, and the hard phase is (M1, M2) (C _1-x , O _x ) _z (hereinafter referred to as equation (1)) or (M1, M2) (C _1-xy , O _x , N _y ) _z (hereinafter referred to as equation (1))
It has a composition as shown in equation (2). M1 is one or two selected from group a metals Ti, Zr, and Hf.
M2 is a group A metal.
One or more metals selected from Cr, Mo, and W. This is clear from the X-ray diffraction shown in FIG. This figure shows the X-ray diffraction pattern of the alloy of the present invention having a composition of 50 at.% W, 25 at.% Ti, 20 at.% C, and 5 at.% O, but only W and TiC phases are observed. In the figure, 1 indicates the peak of W, and 2 indicates the peak of the TiC phase. This also applies to alloys containing N. Here, the limiting conditions of equations (1) and (2) will be explained. First, if x, which is the oxygen content, is too small, its effect will not be exhibited, and if it is too large, the sinterability will be deteriorated. In general, the sinterability of mixtures of oxides and metals is poor because of poor wetting of their interfaces, and the same is believed to apply to the alloys of the present invention. If the range is 0.05≦x≦0.5, a high-strength alloy can be obtained without impairing the effect of oxygen addition. The same thing can be said about nitrogen, but
Since nitrogen may not be desirable when the lowest wear resistance is required, 0.01≦y≦0.5 is considered to be appropriate. Furthermore, if the sum of N and O (x+y) exceeds a limit, sinterability will be impaired. Since it is necessary to contain O of 0.05 or more, the lower limit is also determined and it is desirable that 0.05≦x+y≦0.6. Regarding the stoichiometric constant z, if it exceeds 0.5, the hard phase and carbon coexist, which is outside the scope of the present invention.
Moreover, if it is less than 0.1, the hard phase is too small and the hardness is insufficient, which deviates from the purpose of the present invention as a cutting tool or wear-resistant material. Therefore, it is necessary that 0.1≦z≦0.5. Substituting a part of the group a elements with group a elements such as V, Nb, and Ta is effective in improving toughness. However, when added in large amounts, Me
(CNO) and a high melting point metal phase coexist easily. (M1a, M2b, M3c) (C _1-xy , N _y , O _x ) When expressed as _z , (M1a group element, M2a group element, M3
A group element) a+c is preferably within the range of the amount of the a group element, and is between 0.1 and 0.7, and c/a+c is 0.
It is desirable that it is 3 or less. That is, it is desirable to substitute up to 30 atomic percent of M1a with one or more group a metals selected from V, Nb, and Ta. Note that no effect is observed if the amount of substitution is less than 1 atomic %. It is generally known that the addition of trace amounts of iron group metals, Ag, Pd, Cu, etc. promotes the sinterability of high melting point metals, and this effect is also observed in the alloy of the present invention. It is preferable to add one or more of these metals, as this enables sintering at a lower temperature.
However, these metals have low melting points, and it is clear that if they are added in large amounts, the heat resistance, which is a characteristic of the present alloy, will be reduced. From this point of view, it is desirable to limit the amount of these metals added to 2 atomic % or less. Note that no effect is observed at 0.01 atomic % or less. In this way, carbides, nitrides, oxides, and borides can be coated in a single layer or in multiple layers with carbides, nitrides, oxides, or borides as coating materials, such as TiC,
Coating with TiN, Ti(CN), Al ₂ O ₃ , etc. will result in a tool that can withstand high-efficiency cutting compared to conventional coated cemented carbide base metals. This will be discussed in Examples. It should be noted that the coating method that is effective in the present invention is not limited to the coating method shown in the Examples, and the coating material is not limited to the one shown in the Examples. Example 1 W powder, TiC powder, Ag powder, Pd powder, and Cu powder were weighed out, mixed, pressed, and then sintered under the following conditions. (Model number SNG432, −25゜×0.10mm chamfer honing) 1000℃ Vacuum 10 ^-1 Torr or less 1000 to 1600℃ PCo=100Torr 1600 to 1700℃ Vacuum 3×10 ^-3 Torr 1700℃ Hold for 1 hour, Vacuum 3×10 ^-3 Torr Table 1 shows the composition of the alloy thus obtained and the results of a cutting test performed on this alloy coated with 5 μm of TiC by chemical vapor deposition under the following conditions. Work material: S43C Forging speed: 110 m/min Depth of cut: 6 to 10 mm Feed: 0.86 mm/rev D, G, and H alloys with no additives of Ag, Cu, and Pd outside the range of 0.01 to 2 atomic% It was found that the cutting performance of the alloy was significantly inferior to that of other alloys of the present invention.

[Table] Example 2 An alloy having the composition shown in Table 2 was used as a base metal and coated with 2μ of TiC, 2μ of Ti(CN), and 2μ of TiN by chemical vapor deposition. This was subjected to a milling test under the following conditions. The results are shown in Table 2. Work material: SCM ₃ (plate material with width 600mm and length 1000mm) Speed: 80m/min Depth of cut: 6mm Feed: 0.54mm/Blade tool shape: Axial rake 4゜30' Radial rake -1゜30' Lead angle 25゜Test cutting time with 19.05mm square single blade: 30 minutes

[Table] With commercially available TiC coated chips, the coating film is torn due to severe intermittent milling, which causes defects and shortens the service life. However, with the product of the present invention, chips do not occur due to breaks in the coating film. Since cracking does not progress, the coating film can bring out its good wear resistance. As described above, the present invention can fully utilize the excellent performance of the coating film due to the high base metal toughness.

[Brief explanation of the drawing]

FIG. 1 shows the X-ray diffraction pattern of the alloy of the present invention having a composition of 50 atomic % W, 25 atomic % Ti, 20 atomic % C, and 5 atomic % O. 1...Peak of W, 2...Peak of TiC phase.

Claims (1)

[Scope of Claims] 1 Consisting of a hard phase and a high melting point metal phase, containing 0.01 to 2 atomic % of one or more selected from iron group metals, Ag, Cu, and Pd, with the remainder represented by formula (1) An ingot for coated hard alloys characterized by the following: (M1a, M2b) (C _1-x , O _x ) _z ...(1) However, M1 is a group a metal and is one or more selected from Ti, Zr, and Hf, and M2 is a group a metal. It is a metal and is composed of one or more selected from Cr, Mo, and W. Here, a, b, x, and z all have an atomic ratio of a+b=1, and 0.1≦a≦0.7. 0.05≦x≦0.5, 0.1≦z≦0.5. 2 Consisting of a hard phase and a high melting point metal phase, containing 0.01 to 2 atomic percent of one or more selected from iron group metals, Ag, Cu, and Pd, with the remainder represented by formula (2). Features of base metal for coated hard alloys. (M1a, M2b) (C _1-xy , N _y , O _x ) _z ...(2) However, M1 is a group a metal, one or more selected from Ti, Zr, and Hf, and M2 is a group a metal and is composed of one or more selected from Cr, Mo, and W. Here, a, b, x, y, and z all have an atomic ratio a+b=1, and 0.1≦a≦0.7. Also, 0.05≦x+y≦0.6 and 0.05≦x≦0.5,
0.01≦y≦0.5, 0.1≦z≦0.5. 3 Consisting of a hard phase and a high melting point metal phase, containing 0.01 to 2 atomic percent of one or more selected from iron group metals, Ag, Cu, and Pd, with the remainder represented by formula (3). Features of base metal for coated hard alloys. (M1a, M2b) (C _1-x , O _x ) _z ...(3) However, M1 is a group metal and is one or more selected from Ti, Zr, and Hf, and M2 is a In the family,
One or more selected from Cr, Mo, and W, and 1 to 30 atomic percent of M1 is replaced with one or more of V, Nb, and Ta, which are group a metals. It is. Here, a, b, x, and z all have an atomic ratio of a+b=1 and 0.1≦a≦0.7. 0.05≦x≦0.5, and 0.1≦z≦0.5. 4 Consisting of a hard phase and a high melting point metal phase, containing 0.01 to 2 at% of one or more selected from iron group metals, Ag, Cu, and Pd, with the remainder represented by formula (4). Features of base metal for coated hard alloys. (M1a, M2b) (C _1-xy , N _y , O _x ) _z ...(4) However, M1 is a group a metal and is one or more selected from Ti, Zr, and Hf, and M2 is a group a metal, and is one or more selected from Cr, Mo, and W, and 1 to 30 atomic percent of M1 is one or more group a metals, such as V, Nb, and Ta. It is replaced with metal. Here a, b, x, y,
z is an atomic ratio of a+b=1 and 0.1≦a≦0.7
It is. Also, 0.05≦x+y≦0.6, 0.05≦x≦0.5, 0.01≦
y≦0.5, and 0.1≦z≦0.5.