JPS6043423B2 - Method for manufacturing tool alloy with composite structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a composite sintered tool alloy comprising two or more alloy phases.

Conventionally, a composite sintered body is produced by mixing two or more types of powder, and a material that combines the characteristics of each individual component, such as WC, is produced.
Many attempts have been made to produce -Co cemented carbide and the like.

Although he is a sumo wrestler, in the field of tool materials, the method of sintering the powder mixture described above has not achieved sufficient results so far. For example, in the case of WC-Co superalloy, WC and C
Since Co has a different melting point from Co and Co, Co exists as a bonding layer in the produced composite sintered body. Therefore, in this case, it is only necessary to consider the compatibility of the powders to be mixed. On the other hand, when making tool materials from powdered molten alloys, alloys such as Fe-based, Co-based, and other base alloys, which are themselves tool alloys, are used to improve their properties. Therefore, even if an attempt is made to mix and sinter the powder with other alloy powders, since their melting points are almost the same, there is a problem in that a large amount of alloy layer with an intermediate composition between the two or more components is formed due to diffusion. In addition, when plastic working is performed during the manufacturing process for tool materials, if relatively large voids exist in the sintered body, the voids will remain even after processing, and this will cause the formation of notches, which is a practical disadvantage. There is a problem in that it shows action and impairs toughness. An object of the present invention is to solve the above-mentioned problems and provide a tool material that maximizes the advantages of its constituent components.

In order to achieve the above object, the present invention uses a tool alloy powder with a particle size of 100μ or more as the main component powder, uses a powder with an average particle size of 115 or less of the main component powder particle size as the subsidiary component powder, There is a method characterized by mixing these materials and filling them into a metal container, followed by hot consolidation.

In the present invention, the particle size of the main component powder alone is 10
The reason why it is set to 0μ or more is because if it is less than 100μ, the influence of mutual diffusion that occurs during heating becomes large.

For example, if the main component is SKH-57 gas atomized powder and the subcomponent is SUS53 gas atomized powder, the weight ratio is 85.
FIG. 1 shows the correlation between the particle size of the main components and the hardness of the material when a sintered body was produced after mixing at step 115 and then heat treated.
However, the particle size ratio of both powders at the time of mixing is 5. As is clear from FIG. 1, the hardness decreases rapidly below 100 μm.

In addition, the particle size of the subcomponent powder is set to be 115 or less of the main component powder particle size in terms of its average particle size, in order to add the characteristics of the subcomponent without reducing the characteristics of the main component and to achieve close packing. It's for a reason.

In addition, in the present invention, when adding a third component, the substance that does not cause diffusion between the main component, the second component, and the third component is an oxide, nitride, or a compound having lubricating properties. Although it is possible, it is not necessarily limited to not reacting or diffusing with other component phases. Any component may be used as long as it essentially maintains the functions of other components and is useful for strengthening the bonding of particles that eliminate voids. For example, it is possible to add hydride powder, carbon powder, etc. that react with the oxygen-rich surface layers of the first component and second component to have a cleaning effect. In that case, the purpose of denitrification can be achieved by heating and degassing in the degassing operation before hot consolidation. It is desirable that such a third component is blended in a small amount of 5% or less of the total amount and that it is a finer powder than the second component. The present invention will be explained in detail below based on examples.

Example 1 As the main component powder, a gas powder equivalent to JISSKH-57 was used. 85% Tomized spherical powder (600-850μ)
, 15% of water atomized powder (44 to 104μ) of low carbon stainless steel SUS53 was mixed as a subcomponent.

After thoroughly mixing these, a filling rate of 62.7% was obtained, but since it was impossible to compact the powder, the mixture was tap-filled into a mild steel container, heated at 500°C, degassed, and then subjected to hot isostatic pressing. Consolidation was carried out at 1150°C. At this time, a sufficiently high density was obtained, but further forging was performed to produce a round bar with a working ratio of 10. When examining the cross-sectional structure, it was found that each spherical powder had a long, fibrous structure wrapped around stainless steel. Despite the difference in transformation temperature, there are no cracks or other abnormalities and the steel is good as a tool steel. Example 2 As in Example 1, JISSKH-5'7@ gas atomized powder was used, and 90% of the particles with a size of 250 μm or more and 850 μm or less were mixed with 10% of pure iron powder with a size of 44 μm or less.

Pure iron powder has high thermal conductivity and is thought to improve cutting life, and is insensitive to heat treatment and is thought to be effective in maintaining toughness. The above blend was tap-filled to a porosity of 35%, tightly packed in a mild steel container, deaerated, and then densified by powder extrusion, at the same time giving a processing ratio of 15. As a result, a fiber composite structure with no pores was obtained, which was subjected to standard heat treatment for tool steel, and a tool performance test was performed, which showed extremely good results. Example 3 Polygonal particles obtained by crushing a WC-W2C molten alloy were used as the main component, and 20% of low carbon stainless steel powder was added thereto.

The former has a particle size of 100 to 300p, and the latter has a particle size of 20 to 60μ.
It was hot. Since it is difficult to cold-press the mixture after mixing, the porosity was set to 40% by tap filling. This powder was packed in a mild steel container, sealed by welding, and then processed into a rod shape by hot extrusion. The processing ratio was 9.5. The obtained material had a porosity of about 0.1%, and good results were obtained when this material was ground into wear-resistant machine parts. Example 4 Tool steel powder (JISSKH57
Ni-based 18Cr-18C0-
Gas atomized powder of φ-based heat-resistant alloy was used as a subcomponent.

The former has a diameter of 150μ to 250μ, and the latter has a diameter of 4μ or less.
Additionally, 0.5% zirconium hydride was added (particle size approximately 10μ). This was mixed in a ball mill and then molded under normal pressure using a rubber press. The porosity of the molded body was 35%. After filling this into a mild steel container, the sample was heated to 1000° C. while being evacuated through a degassing pipe. From changes in the degree of vacuum during the process and mass spectroscopy, it was found that the oxides present on the surfaces of the main component and subcomponent powders were considerably reduced. Next, the container was sealed and heated for 12 hours by hot isostatic sintering.
The ingots obtained at 0 (generations) and 15 tapping pressures for 1 hour were hot forged to give a working ratio of 12, and a composite suitable as a void-free tool steel was obtained. As described in Examples 1 to 4 above, in the present invention, a metal container is filled with a porosity of 40% or less, and then this powder is hot consolidated together with the container, and then the processing ratio is 10 or more. More desirable results can be obtained by applying plastic deformation of .

[Brief explanation of the drawing]

FIG. 1 shows the correlation between powder particle size and hardness.

Claims (1)

[Claims] 1. A method of obtaining a tool alloy by using a tool alloy powder as a main component powder, adding and mixing sub-component powders thereto, filling the mixture into a metal container, and then hot-consolidating the mixed powder together with the container. , the particle size of the main component powder is 100μ or more, and
A method for producing a tool alloy having a composite structure, characterized in that the average particle size of the subsidiary component powder is 1/5 or less of the particle size of the main component powder. 2. A method for manufacturing a tool alloy having a composite structure, characterized in that the mixed powder has a porosity of 40% or less in the method according to claim 1. 3. A method for manufacturing a tool alloy having a composite structure, characterized in that, in the method according to claim 1 or 2, after the hot consolidation, plastic deformation is applied at a working ratio of 10 or more.