JPH055105A - Method for extruding alloy powder and production of sintered product of alloy powder - Google Patents

Abstract

PURPOSE:To enhance the degree of freedom of extrusion of a hardly workable material and to enable extrusion with high quality and satisfactory workability by extruding alloy powder mixed and kneaded with a binder having high mol.wt. or ultrahigh mol.wt. CONSTITUTION:Powder of an alloy for surface hardening and build-up welding such as 'Stellite(R)', 'Colmonoy(R)' or JIS D410 is mixed and kneaded with a binder having high mol.wt. of about 100,000-500,000 such as ethylene-vinyl acetate copolymer resin or a binder having ultrahigh mol.wt. of about 1,000,000-3,000,000 such as polybutene. A lubricant such as olein wax, a plasticizer or other component may be added to the binder so as to improve extrudability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for extruding alloy powder and a method for producing a sintered product thereof. More specifically, the present invention provides a Co material having good workability in which the degree of freedom in forming dimensions and shape of an alloy material which is a difficult-to-process material is increased, and the material properties as a surface hardening overlay welding material are also improved. The present invention relates to a method for molding an extrusion molded body of powder such as a base, Ni-based or Fe-based alloy and a method for manufacturing a sintered product from the molded body.

[0002]

2. Description of the Related Art Many Co-based or Ni-based alloy materials are known as difficult-to-machine materials. Also, as the Fe-based alloy material, a material having extremely poor workability is known. For example, a surface-hardening weld material made of a Co-based alloy (such as stellite) is known as such a difficult-to-process material. However, since these materials have almost no ductility, forging, rolling, wire drawing, etc. There is a problem in that it is impossible to obtain a desired size and shape when performing plastic working such as hot or cold, which causes fatal defects.

Therefore, conventionally, the alloy material such as Co base as the surface-hardening welded material has generally been manufactured by a method not mainly including plastic working.
Examples of such a method include a method in which a quartz tube is immersed in molten metal and vacuum suction is performed to obtain a straight rod, and a method in which the molten metal is cast into a sand mold or a low mold is used. Further, in recent years, a metallurgical method has been proposed in which an alloy powder is injection-molded to obtain a molded product having a predetermined shape in a mold.

However, such a conventional method for manufacturing a difficult-to-machine material has some problems to be solved.

That is, in the case of the method using a quartz tube for directly obtaining the required size and shape from the molten metal, the size (diameter) and shape (length) are naturally restricted, and in particular, It was difficult to manufacture a thin and long product. Moreover, the occurrence of internal sink marks, pipes, blowholes, and other defects caused by instability of vacuum pressure during vacuum suction and incomplete removal of generated gas is unavoidable, and is of a quality that is industrially satisfactory. It was also difficult to realize.

On the other hand, in the case of the method of casting in a sand mold or a low mold, the flowability of the molten metal is influenced by the casting size (diameter) and the casting shape (length), for example, a diameter of 5 mm or less or a length of 1 m or more. It is almost impossible to manufacture thin and long ones with a predetermined size and shape, and the quality is also sand kami, blow, sink, simmering that occurs during casting,
It has a drawback that it is not good due to casting defects such as molten metal. That is, the product yield is extremely poor and the product lengths are not uniform.

In the injection molding metallurgical method, which has been attracting more attention recently, much better quality and productivity can be secured as compared with the above-mentioned conventional method, but the process characteristics of injection molding into a mold cause Limited by the size of the mold,
For example, it has been virtually impossible to manufacture a product having a length of 1 m or more. In addition, the powder to be used needs to have a small particle size (up to about 10 μm), and the manufacturing cost of the powder is high.

For welding materials and the like, it is essential that they are thin, long, and their size and shape can be arbitrarily selected, and that the quality is also good. It is not practically satisfactory.

The present invention has been made in view of the circumstances as described above, overcomes the drawbacks of the conventional method for manufacturing a difficult-to-process alloy material, and allows free molding of the size and shape of the difficult-to-process alloy material. It is an object of the present invention to provide a method for producing a new alloy material which has high quality, high quality and good workability.

More specifically, the object of the present invention is to provide an extrusion molding method of alloy powder by a completely new method and a manufacturing method of a sintered product from a molded body obtained by the method.

[0011]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention comprises mixing and kneading an alloy powder with a high-molecular weight or ultra-high-molecular weight binder and extruding from a molding nozzle under heating. An extrusion molding method of alloy powder is provided. Further, the present invention is characterized in that the extruded body of the alloy powder obtained by this method is heated in a protective atmosphere of an inert gas or a reducing gas to remove the binder, and is heated and sintered in a vacuum. A method of manufacturing a sintered product is also provided.

In forming the extruded body, the alloy powder is first mixed and kneaded with a high molecular weight or ultra high molecular weight binder. The alloy used in this case is, for example, Co.
Alternatively, a Co-based alloy or a Ni-based alloy containing 50% by weight or more of Ni is mainly exemplified. of course,
Even if the content ratio is less than that, the main component is Co or N
The alloy of i and the like are also included in the scope of this invention. This Co
In addition to Ni, Cr, Mo, W, Mn, C, S
i, P, S, etc. can be contained. Furthermore, even Fe-based alloys can be targeted if they are difficult-to-machine materials.

Examples of such alloys include stellite, colmonoy, and J as alloys for surface-hardening overlay welding.
IS D410 or high speed steel can be exemplified, and the particle size of the alloy powder is typically several μ.
It is possible to exemplify one having a thickness of m to several tens of μm. Further, intermetallic compounds such as Ni-Ti and Ti-Al can be used.

As the binder to be mixed and kneaded with these alloy powders, a high molecular weight binder having a molecular weight of about 100,000 to 500,000 or an ultrahigh molecular weight binder having a molecular weight of about 1,000,000 to 3,000,000 can be preferably used. Examples of the high-molecular weight binder include ethylene vinyl acetate copolymer resin, and examples of the ultra-high molecular weight binder include polybutene. By mixing and kneading these binders with the alloy powder, the powders can be combined and extruded.

Further, in order to improve the extrusion moldability, a proper component such as a lubricant and a plasticizer may be added and used in combination with the binder. For example, as a lubricant, olein wax can be preferably used. The amount of the organic component used including these additive components is about 15% by weight or less, and more preferably 10% by weight or less. If the amount is too large, the shape retention property deteriorates.

There is no particular limitation on the type of apparatus for mixing and kneading the binder and the alloy powder.

The kneaded product of the alloy powder and the binder is extruded from a molding nozzle to obtain a molded product having a predetermined size and shape. The temperature at the time of this extrusion molding is generally 180 ° C. or less,
More preferably, the temperature is 150 ° C or lower. The shape and length of the forming nozzle are not particularly limited, and for example, in the case of obtaining a formed body for a surface-hardened overlay welding material, practically, 0.
A nozzle having a diameter of 5 to 12 mm and a length of about 45 to 200 mm can be exemplified as a suitable nozzle.

When a linear molded body is obtained by using a nozzle having the above diameter and length as a molded body for a welding material, for example, as shown in FIG. 1, temperature, pressure, speed, etc. From the extrusion molding nozzle (1) where the conditions are set appropriately,
It is possible to extrude onto a movable setter (3) having a groove (2) and obtain a linear extruded body (4) along the groove (2). The setter (3) may be fixed and the molding nozzle (1) may be moved back and forth and left and right. With this setter (3), a molded body (4) of the required shape and dimensions
Can be obtained efficiently and uniformly. When the setter (3) is made of heat-resistant ceramic or the like, it is possible to move to the next heating and sintering step with the molded body (4) still on.

Alternatively, as shown in FIG. 2, a cylindrical setter (5) made of ceramic, graphite or the like.
Further, the extruded compact (4) from the nozzle (1) can be wound up to obtain a compact (4) on the coil having a required size and shape.

Of course, the size and shape of the extruded product are not limited to the above examples. It can be made appropriate depending on the shape of the nozzle discharge port, the shape and size of the setter, and the like.

The extruded body shaped in this way can then be sintered. Sintering at this time is carried out by heating the extruded body under a protective atmosphere of an inert gas or a reducing gas to remove the binder, and then by heating and sintering under vacuum as described above.

The heating for removing the binder is a process positioned as degreasing under a protective atmosphere, and nitrogen,
Heating is performed in an atmosphere of an inert gas such as argon or a reducing gas such as hydrogen gas. Generally, the binder and the lubricants and plasticizers used in combination with it are decomposed and removed by heating to a temperature of around 500 ° C, deoxidation is performed, and then dehydrogenation is performed.
The residual amount of the organic component is preferably reduced to 1% by weight or less so that the organic component does not substantially remain.

Then, in vacuum, generally 1200
Sinter by heating to a temperature of ~ 1400 ° C. The temperature at this time is
It can be selected according to the composition of the molded product, the required properties and the like. Further, the sintering time can be about 0.5 to 1.5 hours. Of course, this temperature and time are not limited.

For example, in the case of producing a surface-hardening welded sintered product from a Co-based alloy powder, the relative density is 8
It is preferable to obtain a sintered product having a ductility that is densified to 0% or more and elongation of 5% or more is obtained. Such a sintered product has not been realized by any of the conventional methods.

The present invention will be described in more detail below with reference to examples.

[0026]

EXAMPLES Example 1 The following chemical composition (%); Cr: 28.00 to 32.00 Mo: ≤ 0.60 W: 3.50 to 5.00 Ni: ≤ 1.50 C: 1.00 to 1.40 Si: 0.90 to 1.30 Mn: ≤ 1.00 P: ≦ 0.030 S: ≦ 0.030 Fe: ≦ 1.50 Stellite No. 6 (JIS D CoCrA) spherical alloy powder (average particle size 25 μm) consisting of the balance Co, an ultra-high molecular weight polybutene binder with an average molecular weight of about 2,000,000, and an olefin. Mix with wax and plasticizer and knead.

The alloy powder kneaded product was extruded at a temperature of 130 ° C. from various nozzles having a diameter of 0.5 to 10 mm and a length of 120 mm into the grooves of a ceramic setter having the shape shown in FIG. With this extrusion, Co of various diameters with a length of 180 mm
A base alloy powder extrusion molding was obtained. A coil-shaped extruded body was obtained by using the cylindrical center shown in FIG.

Then, the above-mentioned molded body is heated in a degreasing and sintering furnace at 50 ° C. in an atmosphere under a flow of hydrogen gas of 5 l / min.
The sample was heated to 450 ° C. at a heating rate of / hour, kept at a temperature of 450 to 550 ° C. for 2 hours, and then heated to 1280 ° C. at a heating rate of 250 ° C./hour. At this time, the furnace was evacuated at a temperature of 1000 ° C.

The degree of vacuum was 5 × 10 −4 Torr.

The temperature was maintained at 1280 to 1300 ° C. for 1 hour, and then the temperature was raised at a rate of 150 ° C./hour to complete the sintering.

The obtained sintered product had a predetermined size and shape as a surface-hardened weld overlay material, and no defects were recognized on its surface.

The build-up hardness was HRC43 or more, the strength was excellent, and the elongation was 5% or more.
Further, during welding, there was no breakage of the welding material, and it had excellent performance as a welding material.

Although this embodiment is an example in which spherical alloy powder is used, the same effect can be obtained by using irregularly shaped powder. Example 2 As a binder, an ethylene vinyl acetate copolymer resin having an average molecular weight of 300,000 was used as a binder, and extrusion molding was performed in the same manner as in Example 1, and the obtained molded body was sintered.

A weld material having excellent characteristics was obtained in the same manner as in Example 1.

[0035]

As described in detail above, according to the present invention, the degree of freedom in the manufacture of a difficult-to-process material has hitherto been low,
In addition, there were many problems in terms of quality and productivity.
A material such as an i-based alloy can be realized as a molded product that is easily manufactured, has high productivity, and has high quality by extrusion molding and sintering of alloy powder.

A high quality, low cost product of a Co-based or Ni-based surface-hardened welding material is also provided.

[Brief description of drawings]

[Figure 1]

FIG. 2 is a perspective view illustrating a method for manufacturing an extruded product according to the present invention.

[Explanation of symbols]

 1 molding nozzle 2 groove 3 setter 4 molded body 5 setter

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[Procedure amendment]

[Submission date] July 31, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief explanation of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a method for manufacturing an extruded body according to the present invention.

FIG. 2 is a perspective view illustrating a method for manufacturing an extruded product according to the present invention.

[Explanation of symbols] 1 molding nozzle 2 groove 3 setter 4 molded body 5 setter

Claims (1)

Claim: What is claimed is: 1. An alloy powder extrusion molding method, comprising: mixing and kneading an alloy powder with a high molecular weight or ultra-high molecular weight binder, and extruding the mixture under heating with a molding nozzle. 2. The extrusion molding method according to claim 1, wherein a high molecular weight binder having a molecular weight of 100,000 to 500,000 is mixed and kneaded. 3. The extrusion molding method according to claim 2, wherein the ethylene vinyl acetate copolymer resin is used as a binder. 4. The extrusion molding method according to claim 1, wherein an ultrahigh molecular weight binder having a molecular weight of 1,000,000 to 3,000,000 is mixed and kneaded. 5. The extrusion molding method according to claim 4, wherein polybutene is used as a binder. 6. An olefin wax is mixed as a lubricant.
The extrusion molding method according to claim 1, wherein kneading is performed. 7. The extrusion molding method according to claim 1, wherein the powder of the surface-hardening overlay welding alloy is extruded into a linear shape or a coil shape. 8. An alloy powder, characterized in that the extruded body obtained by the method of claim 1 is heated in an atmosphere of an inert gas or a reducing gas to remove the binder, and heat-sintered under vacuum. Sintered product manufacturing method.