JPS6246622B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to composite parts that are partially heat and wear resistant. BACKGROUND ART Cemented carbide, which has excellent wear resistance, has been widely used in parts such as rolls and dies that require wear resistance. However, it is clear that all parts of the roll and die do not necessarily need to be wear resistant, and it is sufficient if a certain range of the contact area with the workpiece is made of an alloy with high wear resistance. Therefore, they are made composite by methods such as brazing with steel or other metals, shrink fitting, etc., and are manufactured to suit these purposes. However, brazing not only causes brazing distortion, but also has poor heat resistance of the brazing material itself, which limits its range of use. Shrink fitting does not have the above-mentioned problems, but shrink fitting requires strict dimensional accuracy, and cemented carbide, which is difficult to grind, is expensive. Furthermore, as a solution to these problems, there is also a method of thermal spraying cemented carbide onto the steel surface. This method allows the base steel to be machined and the cemented carbide to be bonded along this surface, making it possible to create the configuration that best suits the purpose. However, this method also has problems. This is because the strength of the interface between the thermally sprayed carbide and the steel tends to be insufficient, and because the precision of the thermally sprayed coating is poor, it is rather difficult to make complex shapes. The inventors have studied methods of partially using hard alloys as described above, and have come up with a hard alloy that enables manufacturing methods that were not possible with conventional cemented carbide. It uses a hard alloy with a high melting point and embeds it in molten metal. In this case, if the outer wall of the mold is made of a hard metal, a part with high wear resistance will be created on the outside. There are two reasons why this has not been possible with conventional cemented carbide. First of all, the casting temperature of steel and cast iron, which are the most common structural materials, is 1400°C or higher, which exceeds the melting point of cemented carbide, 1320°C. Second, cemented carbide becomes weaker due to the reaction with molten metal. In order to solve these problems, it is necessary that the cemented carbide itself has high heat resistance and has little reaction with molten metal. For hard alloys to meet these objectives, it is desirable that the binder phase metal has a higher melting point. The idea of such an alloy is found in Cast Alloys by E. Rudy (U.S. Pat. No. 3,779,745) and in Japanese Patent Application No. 52-112,943. Because of their composition, these alloys have higher heat resistance than cemented carbide, and because they do not use iron group metals, they are characterized by less reaction to steel and copper, which are commonly used as structural materials. Therefore, it meets the purpose of the present invention very well. Next, embodiments of the present invention will be described. The manufacturing method of the present invention can be considered to be almost the same technology as a general casting method. However, as mentioned above, a hard alloy with a high melting point metal as a binder phase is installed in the necessary areas, and molten metal is poured in. Therefore, when the entire outside is made of a hard alloy, the alloy itself can be used as a mold, but in other cases, casting is carried out using commonly used molds such as sand, ceramic, or metal. Now, the most important thing in the present invention is the selection of the hard metal. That is, for general parts using steel, copper, aluminum, etc., it is desirable that the melting point of the binder phase is 1700°C or higher, but according to the inventors' experiments, the melting point of the binder phase is mainly W and Mo. This is considered to be economically preferable. Therefore, hard phases that may exist in these binder phases include carbides, nitrides, etc. of group a and group a elements. E mentioned earlier.
The proposal by Rudy and the inventors present two methods of manufacturing these alloys. The former method is a melt-casting method, which makes it difficult to create complex shapes, and requires rapid cooling, making it unsuitable for manufacturing large parts and limiting its scope of use. Therefore, it is considered more preferable to create it by powder metallurgy. The latter is a powder metallurgy method, and as described in detail by the inventor in Japanese Patent Application No. 112943/1983, the key to production by the powder metallurgy method is to have oxygen present in the hard phase. Here, the limited range of the hard alloy of the present invention will be described. The main feature of the present invention is that oxygen is actively introduced into the hard phase, but in this alloy, almost no oxygen is needed outside of the hard phase, and the hard phases are (M1a, M2b) (Cl-x, Ox)z (hereinafter referred to as equation (1)) or (M1a, M2b) (C1−x−y, Ny,
Ox)z (hereinafter referred to as equation (2)). M1 is one or more metals selected from group a metals Ti, Zr, and Hf, and M2 is a
One or more metals selected from group metals 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 with a composition of W50 at%, Ti25 at%, C20 at%, and O5 at%.
Only the TiC phase is observed. 1 in the figure is the peak of W,
2 shows the peak of the TiC phase. This also applies to alloys containing N. In the above formulas (1) and (2), a, b, x, and y are the mole fractions of the respective elements, z is the nonmetallic element C relative to the metal,
This is the total molar fraction of O and 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. Generally, the sinterability of mixtures of oxides and metals is poor due to poor wetting of their interfaces.
The same is conceivable for the alloys of the 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 as for enzymes, but since nitrogen may be undesirable when the lowest wear resistance is required, it is considered appropriate that 0<y<0.5. Furthermore, if the sum of N and O (x+y) exceeds the limit, sinterability will be impaired. It is necessary that the content of O exceeds 0.05, and 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 Va elements such as V, Nb, and Ta is effective in improving toughness.
However, when added in large amounts, the combination of Group A and Group A high melting point metals becomes characteristic. Me
(CNO) and a high melting point metal phase coexist easily. (M1a, M2b, M3c) (C1-x-y, Ny, Ox)
When expressed as z (referred to as formula (4)), (M1a group metal,
M2a group metal, M3Va group metal) a+c is preferably within the range of the amount of group a metal as described above.
Desirably, it is between 0.1 and 0.7, and c/a+c is 0.3 or less. 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 recognized 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 obvious 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. Furthermore, the use of the alloy of the present invention, which is mainly composed of W, is particularly effective in parts that are subjected to impact. In this case, the addition of Re helps strengthen the W phase, as is well known. Moreover, Na, Ca, K, Al, and Si are effective in optimizing the crystal grain size of the W phase. However, the addition of these elements should be limited to 5 atomic % or less because Re is expensive, and other elements precipitate a large amount of oxides, making it brittle. Since this alloy is characterized by its heat resistance, the addition of Mo should be 30 atomic percent or less of W. However, it is an important design factor for alloys used in rotating objects, etc., to have a low specific gravity, and in this case, alloys containing Mo as the main component are preferable. When Mo is the main component, the higher the strength, the higher the N content.
In formula (4), y should be 0.05 or more, preferably 0.1 or more. Cr itself has low strength, and composition (1) tends to produce brittle phases, so it is difficult to use it alone. However, it is well known that addition of a small amount is effective in improving corrosion resistance. In casting using these alloys, there is a risk of oxidation since the hard alloy of the present invention is exposed to high temperatures in an oxidizing atmosphere unless a vacuum casting method is used. Therefore, cooling the hard alloy with water or coating it with a non-oxidizing film are effective methods. Although oxides are optimal as a coating, care must be taken as oxides weaken the adhesive strength at the interface with the cast metal. On the other hand, some films of nitrides and carbides are effective without such problems. The coating is PVD, CVD,
There are methods such as plasma CVD, but the method is not particularly limited. The present invention will be explained below with reference to examples, but the present invention is not necessarily limited to hard alloys made by powder metallurgy, nor is the composition in the examples limited to hard alloys. . Example 1 86% W powder with an average particle size of 1μ and an average particle size of 1μ
Weigh out 14% TiC, mix it in a wet ball mill, go through a dry embossing process, and sinter it under the following conditions, with an inner diameter of 10 mm.
A cylinder with an outer diameter of 15 mm and a height of 40 mm was created. ～1100℃ Vacuum 5×10 ^-1 Torr or less 1100～1750℃ Pco=150Torr 1750～1850℃ Vacuum 1×10 ^-1 Torr or less The composition of this alloy is (W ₀ . ₆₆ Ti ₀ . ₃₄ ) (C ₀ . _{80 O 0.2
0} ) _{It was 0.36 .} This metal was placed in the center of a cylindrical sand mold with a diameter of 50 mm and a height of 40 mm, and cast steel containing 0.45% C and 0.6% Mn was cast. After cooling, this was released from the mold and machined to create a one-piece die. In this die, there was almost no reaction between the cast steel and the hard alloy, and the properties of the hard alloy were good with almost no change from before casting. When this die was used for wire drawing of mild steel,
It showed five times the lifespan compared to conventional cemented carbide dies. Example 2 _An alloy of (W _0.60 Ti _0.40 ) ( _{C 0.72 N 0.08 O 0.20} ) _0.38 was used in the same _manner as in Example 1. However, in this case, this hard alloy has an outer diameter of
It had a shape of 303mmφ, inner diameter 280mmφ, and height 100mm. This was placed in a sand mold with an inner diameter of 303 mmφ and a height of 130 mm, and cast steel containing 0.30% C, 0.95% Mn, and 50% SiO was cast into it.
Finished by machining into a rolling roll with mmφ and width of 100mm. This roll was used as a roll for hot rolling steel strips, and showed three times the lifespan of conventional chilled rolls. Example _{3 A hard alloy of (Ti 0.35 Mo 0.60 Ta 0.05 ) ( C 0.65 N 0.20 O 0.15 ) 0.30} was prepared _in the same manner as in _Example 1 _. In this case, the hard alloy had an inner diameter of 20 mmφ, an outer diameter of 30 mmφ, and a height of 50 mm. Cu88%, Al9.0%,
Cast aluminum bronze with a composition of 3.0% Fe. The present invention was made for use in molds requiring heat dissipation and exhibited three times the lifespan of conventional die steel. However, when a prototype was produced using a WC-10% Co superalloy as a cemented carbide, Co diffused from the cemented carbide and the interface with the cast alloy became brittle, making it unusable. It broke on the 10th use. Example 4 A guide roller for hot wire rod rolling was prepared in the same manner as in Example 1 by combining a hard alloy having the composition shown in Table 1 and cast steel having a composition of 0.30% C and 1.2% Mn. The wire temperature of the stand using this guide roller is estimated to be 1100℃. Table 1 shows the weight passed through the life of each prototype.

[Table] Note that the specific gravity of the hard alloy parts of the present invention is
14.0, which caused the bearing to wear out. On the other hand, the products of the present invention listed in Table 1 had a specific gravity of 11 or less.

[Brief explanation of the drawing]

Fig _{. 3 shows an X-ray diffraction pattern of a hard alloy of the present invention having a composition of (Ti 0.33 W 0.67 ) ( C 0.80 0.20 ) 0.33 .} In the figure, 1 indicates the peak of W, and 2 indicates the peak of the TiC phase.

Claims (1)

[Claims] 1. A hard alloy consisting of a hard phase and a high melting point metal is used in parts where heat resistance and wear resistance are required,
In a composite material part in which the remaining part is a cast alloy and/or an alloy, the total composition of the hard alloy is (1)
A heat-resistant and wear-resistant composite material part characterized by being represented by the formula. (M1a, M2b) (Cl-x, Ox)z ...(1) However, M1 is a group a metal selected from one or more of Ti, Zr, and Hf, and M2 is a group a metal.
It is composed of one or more selected from Cr, Mo, and W. Here, a, b, x are mole fractions, z is the total mole fraction of C and O relative to the metal, and a+
b=1, 0.1≦a≦0.7, 0.05<x≦0.5, 0.1≦z
≦0.5. 2. For parts that require heat resistance and wear resistance, use a hard alloy consisting of a hard phase and a high melting point metal.
In a composite material part in which the remaining part is a cast alloy and/or an alloy, the total composition of the hard alloy is (2)
A heat-resistant and wear-resistant composite material part characterized by being represented by the formula. (M1a, M2b) (Cl-x-y, Ny, Ox)z ...(2) However, M1 is one or more group a metals selected from Ti, Zr, and Hf, and M2 is a group a metal. in
It is composed of one or more selected from Cr, Mo, and W. Here, a, b, x, y are mole fractions,
z is the total mole fraction of C, N, and O relative to the metal, a+b=1, 0.1≦a≦0.7, 0.05<x+y<
0.6, 0.05<x≦0.5, 0<y≦0.5, 0.1≦z≦0.5
It is. 3. For parts where heat resistance and wear resistance are required, hard alloys consisting of hard phase and high melting point metals are used.
In a composite material part made of a cast alloy and/or alloy for the remainder, the metal phase in the hard alloy is a high melting point metal, an iron group metal, and one or more metals selected from Ag, Cu, and Pd. A heat-resistant and wear-resistant composite material part, characterized in that the hard phase of the hard alloy contains 2 atomic % or less (not including O), and the total composition of the hard phase in the hard alloy is represented by formula (3). (M1a, M2b) (Cl-x-y, Ny, Ox)z ...(3) However, M1 is one or more group a metals selected from Ti, Zr, and Hf, and M2 is a group a metal. in
It is composed of one or more selected from Cr, Mo, and W. Here, a, b, x, y are mole fractions,
z is the total mole fraction of C, N, and O relative to the metal, a+b=1, 0.1≦a≦0.7, 0.05<x+y<
0.6, 0.05<x≦0.5, 0<y≦0.5, 0.1≦z≦0.5
It is. 4. For parts that require heat resistance and wear resistance, use a hard alloy consisting of a hard phase and a high melting point metal,
In a composite material part in which the remaining part is a cast alloy and/or an alloy, the total composition of the hard alloy is (4)
A heat-resistant and wear-resistant composite material part characterized by being represented by the formula. (M1a, M2b, M3c) (Cl-x-y, Ny, Ox)z
...(4) However, M1 is a group a metal selected from one or more selected from Ti, Zr, and Hf, and M2 is a group a metal.
One or more selected from Cr, Mo, W,
M3 is a group a metal and is composed of one or more selected from V, Nb, and Ta. Here a, b,
c, x, y are mole fractions, z is C relative to metal,
The molar fraction of the total of N and O, a+b+c=1,
0.1≦a+c≦0.7, c/(a+c)≦0.3,
0.05<x+y<0.6, 0.05<x≦0.5, 0<y≦
0.5, and 0.1≦z≦0.5. 5. For parts that require heat resistance and wear resistance, use a hard alloy consisting of a hard phase and a high melting point metal,
In a composite material part made of a cast alloy and/or alloy for the remainder, the metal phase in the hard layer is a high melting point metal, an iron group metal, and one or more selected from Re, Na, K, Al, and Si. 5 atomic% or less (O
1. A heat-resistant and wear-resistant composite material part, characterized in that the entire composition of the hard phase is represented by the formula (5). (M1a, M2b, M3c) (Cl-x-y, Ny, Ox)z
...(5) However, M1 is a group a metal selected from one or more selected from Ti, Zr, and Hf, and M2 is a group a metal.
One or more selected from Cr, Mo, W,
M3 is a Va group metal and is composed of one or more selected from V, Nb, and Ta. Here a, b,
c, x, y are mole fractions, z is C relative to metal,
The molar fraction of the total of N and O, a+b+c=1,
0.1≦a+c≦0.7, c/(a+c)≦0.3,
0.05<x+y<0.6, 0.05<x≦0.5, 0<y≦0.5
and 0.1≦z≦0.5.