JPS63286535A - Manufacture of worked product of hard-to-work alloy - Google Patents

Abstract

PURPOSE:To simply and easily manufacture a worked product of hard-to-work alloy, by mixing respective powders of high-ductile metal and low-ductile metal in the prescribed ratio to carry out mechanical alloying and by subjecting this powdery material to compacting and to annealing so as to alloy both metals. CONSTITUTION:Metallic components constituting a difficult-to-cold-form alloy is sorted into metals having superior ductility and metals having inferior ductility. These high-ductile metal powder and low-ductile metal powder are mixed so that desired alloy composition is reached. The resulting powder mixture is formed into a powdery material having a composite structure in which the low-ductile metal powder is mechanically dispersed into the matrix of the high- ductile metal by a mechanical alloying method. Subsequently, in the state of the above-mentioned composite structure, the powdery material is subjected to compaction by rolling reduction to undergo mutual joining of the high-ductile metal and/or to presintering. The resulting preformed body is subjected, if necessary, to process annealing and then to cold working into the shape of the final product. Then, annealing is applied to the above-mentioned worked product to alloy both metals, so that desired worked product with hard-to-work alloy structure can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the processing of difficult-to-form alloys, which allows alloy materials that are difficult or virtually impossible to cold-form to be processed into desired products by cold-working. Concerning the manufacturing method of the product.

[Conventional technology and problems]

A large number of various excellent alloys have been developed so far. For example, Sendust and Feclaroy as magnetic materials have very excellent properties. However, a common problem with such alloys is that they are extremely difficult to form. For this reason, molding is performed using a special technique 1, such as HIP processing or extrusion processing of rapidly cooled spray powder. In addition, lN-10 is used as a super heat-resistant alloy in jet engines, etc.
The 0 alloy is formed by a superplastic isothermal forging method called the Gatorizing method by Pratt & Whitney.

For this reason, the various difficult-to-work alloys that have been developed so far have to be extremely expensive materials in terms of manufacturability and formability, which makes them unusable for general use. There's a problem.

If a means to process and form these various difficult-to-work 0 alloys using hour wheels at low cost could be established.

Its utility value will increase dramatically.

[Purpose of the invention]

The present invention enables relatively simple and easy processing of difficult-to-process alloys.
This was done for the purpose of establishing molding technology.

[Summary of the invention]

The gist of the present invention, which aims to achieve the above object, is that among the metal components constituting an alloy that is difficult or virtually impossible to cold work or form, a metal with high ductility and a metal with low ductility are used. A metal powder with high ductility and a metal powder with low ductility are sorted and prepared, and the prepared metal powder with high ductility and the metal powder with low ductility are mixed to have a target alloy composition, and this mixed powder material is mixed. A powder material with a composite structure in which a metal powder with poor ductility is mechanically dispersed in a matrix of a highly ductile metal is obtained by subjecting it to a mechanical alloying method, and the powder material with a composite structure substantially maintains this composite structure. Preliminary preparation of a ductile composite structure by applying sufficient rolling pressure to bond the ductile metals together and/or performing preliminary sintering under conditions that maintain the composite structure. A compact is produced, the preform is cold-worked to the shape of the final product with or without intermediate annealing, and the workpiece is alloyed with a more ductile metal and a less ductile metal. It is characterized by annealing at a sufficient temperature and time to form the target difficult-to-work alloy structure.

In other words, the present inventors focused on the fact that even in difficult-to-work alloys, the constituent elements may contain highly ductile metals, and attempted to process and form them using these ductile metals. This led to the present invention. As a process for processing and forming, fine particles of metal with poor ductility are mechanically embedded and dispersed in a matrix of fine powder of metal with high ductility to the extent that the ductility of the matrix is not significantly inhibited. After manufacturing the powder, we created a preformed product with a ductile composite structure in which the ductile metal matrix in this powder was bonded to each other.

The basic feature of the present invention is that it employs a method of subjecting this material to processing. The 2-alloying process is then performed by annealing this final processed product.

The metal powder with poor ductility used in the method of the present invention may be either a pure metal element powder, an alloy powder, or an intermetallic compound. Therefore, in this specification, the term "metal powder with poor ductility" is used to include alloy powder with poor ductility and intermetallic compounds with poor ductility. In addition, it is preferable that the ductile metal powder and the less ductile metal powder used be fine powders with a particle size in the range of 0.1 μm to 20 μm, and the ductile metal powder should have a volume of at least 40 μm in the mixed material. % or more is preferable.

[In carrying out the detailed description of the invention, first, among the components constituting the difficult-to-work alloy, a fine powder of a highly ductile metal and a fine powder of another metal powder having poor ductility are produced. The particle size of both fine powders is 0.1μ
Fine powder in the range of m to 20 μm. Then, these are mixed to form a composition of a difficult-to-work alloy, and this mixed material is placed in a metal matrix with poor ductility using a mechanical alloying method.
A composite material having a two-phase structure in which particles (which may be fine particles of an alloy or an intermetallic compound) are mechanically embedded is prepared. In creating this composite material, the smaller the particle size of the metal 1 alloy or intermetallic compound particles to be dispersed in the ductile metal, the easier the subsequent processing and diffusion treatment will be. For this reason, the metal powder with poor ductility should desirably be at least 5 μl or less.
It is better to use one below the μ range. Such fine powder is also formed during the mechanical alloying process.

Mechanical alloying of powders can be carried out using, for example, a machine containing rigid balls in a rotating drum. At this time, if easily oxidizable powder is used, it is preferable to maintain an inert atmosphere in the drum. According to the mechanical alloying method, the raw material powder is crushed to form a new surface.

In addition, the raw material powder is plastically deformed by the impact of the ball. As this deformation progresses, the contaminated film on the surface is destroyed and a new surface is exposed, causing cold bonding of the raw material powders, and at the same time, the powders that have become too large due to bonding cannot withstand plastic deformation and are forced to re-grind. happen. By repeating this re-grinding and joining, different kinds of raw material powders are folded into fine particles to form a composite material. In other words, using the mechanical alloying method, it is possible to create a composite powder in which fine particles are dispersed without oxidizing the surface. This cannot be obtained by normal mechanical mixing6. For example, when making a sintered body of easily oxidized powder such as St and Fe powder, a thin Si or oxide film is inevitably formed on the surface of the Si. Therefore, even if these two types of powders are simply mechanically mixed and then sintered, the SiO2 film will significantly inhibit diffusion and make it extremely difficult to achieve uniformity.

This can be avoided with the mechanical alloying method.

Next, in the present invention, the composite powder obtained by the mechanical alloying method is used to prepare a preform for subsequent processing.

The purpose of this preforming is to maintain a composite structure in which fine particles with poor ductility are dispersed in a ductile metal matrix, while bonding the ductile metal matrices to the extent that plastic processing is possible. For this preforming, cold pressing, CIP, or powder rolling can be used, but if this method still does not provide sufficient shape retention strength as a preform, a ductile metal matrix and dispersed in the preform may be used. Further sintering may be performed at a temperature and time within a range where diffusion of fine particles having poor ductility can be ignored. Also,
It is also possible to produce a cake-like preformed product with a highly ductile composite structure by sintering a light green compact under these conditions.

In the present invention, the obtained preform has a composite structure in which fine particles (fine particles of metal 1 alloy or intermetallic compound having poor ductility) are dispersed apart from each other in a highly ductile metal matrix. This means that the ductile metal will bear most of the deformation caused by processing. In this case, the larger the amount of the highly ductile metal matrix, the easier the processing becomes, so it is preferable that the amount of the ductile metal powder be at least 40% by volume at the initial powder mixing stage.

Next, after processing this preform into a predetermined final shape, annealing is performed in a temperature range where this molded body does not melt.
An alloy with a uniform composition is obtained by diffusing finely dispersed particles into a matrix.

- In the middle of processing to the final shape, as long as alloying progresses due to diffusion of dispersed particles during annealing and does not deteriorate workability, intermediate annealing may be performed at least once to improve workability. This processing can be done cold.

In the final annealing diffusion treatment, in order to achieve more uniform and rapid diffusion, rather than using pure metal as fine particles with poor ductility, it is preferable to use an alloy powder with the metal that constitutes the highly ductile metal matrix. It is preferable to use In this case, by using two-alloyed powder, the activity of each constituent element of the alloy can be increased.
Since fl is also lowered, there is an advantage that oxidation is less likely to occur.

In this manner, according to the present invention, even difficult-to-work alloys can be relatively easily formed into final products.

Various excellent alloys that could not be widely used due to their difficult-to-process properties can be provided to the market at low cost. Therefore, the method of the present invention can be applied to any conventional difficult-to-work alloy that contains a relatively large amount of a relatively ductile metal as an alloying element. In addition, it can be applied to forming various alloys.

Examples in which the present invention is applied to an iron-based alloy as a difficult-to-work alloy will be listed below as representative examples, but the method of the present invention is not limited to these examples.

[Example 1] Atomized iron powder 150 with an average size of 15 μm manufactured by Kojundo Kagaku ■
Silicon powder Log with an average particle size of 5μ made by g and Kojundo Kagaku ■
After mixing thoroughly, use an attritor manufactured by Mitsui Miike Kako ■ to N! Mechanical alloying was performed in an atmosphere for 12 hours with a zero rotation speed of 200 rpm and the ball used had a diameter of 5I.
llI high Crt! ! It is 4.

The obtained powder was cold pressed at a pressure of 5 ton/cd to create a disc with a diameter of 5c+++ and a thickness of 4mm, and this disc was sintered at C for 10 minutes in an H2 atmosphere for 12 hours to obtain a preformed product. I got it.

The disk of this preform was then rolled to a thickness of 110 μm without intermediate annealing, and the resulting thin plate was heated at 1200°C.
After diffusion heat treatment in 8 atmosphere for 10 hours, further 90μ
It was rolled to m. Then, a final diffusion heat treatment was performed at 1200°C for 10 hours to obtain an iron-silicon alloy.

Dumbbell pieces with a width of 12.5 mm and gauge length #50 mm were made from the obtained iron-silicon alloy, and the tensile speed was 4.2 x 1.
A tensile test was conducted at a speed of 0-8 m/s. As a result, the tensile strength was 62 kgf/I1m'' and the yield strength was 51 kgf/mm.
"Met.

This is about 10% higher than commercially available 3.2% silicon steel.
kgf/m+w'', both tensile strength and yield stress are strong.

[Comparative Example 1] The same atomized iron powder and silicon powder used in Example 1 were mixed, and this was melted in a high frequency melting furnace in an H2 atmosphere to obtain Fe-Si containing about 5.8% SI. make an alloy,
After cutting this into a thin plate with a thickness of about 21 mm, an attempt was made to roll this alloy sample, but cracks appeared immediately and rolling was impossible.

[Example 2] After thoroughly mixing 150 g of the same iron powder as in Example 1 and 20 g of ferrosilicon (silicon content 50 wt,
A disk with a diameter of 1.0 mm was prepared, and this disk was sintered at 1100° C. for 15 minutes in an H atmosphere to produce a preform.

This preform was rolled to a thickness of 120μ. This thin plate was then subjected to diffusion heat treatment at 1200° C. for 12 hours in a Hz atmosphere to obtain an iron-silicon alloy.

This alloy was observed by EPMA.

Although there were some areas where the Si concentration was high, it was confirmed that Si was almost uniformly distributed. In addition, the iron loss was measured * 0.58 (WaH/kg) at WIt/S@
I got it. This has a lower core loss value than commercially available 3.2% SI silicon steel sheets, and has excellent properties as an electromagnetic material.

[Example 3] 150 g of atomized iron powder with an average particle size of 40 μm and 7S Rochrome powder with an average particle size of 30 μm (Cr content 61.9 wt,
) 75 g was subjected to mechanical alloying under the same conditions as in Example 1, except that the mechanical alloying treatment was carried out for 24 hours. The obtained composite powder was cold-pressed at a pressure of 5 ton/cm'' to create a disk with a diameter of 5 mm and a thickness of 3 nm+m, and this disk was annealed at 1200°C for 20 minutes in an H atmosphere to preform. I got the item.

This disk-shaped preform was cold rolled to a thickness of 200 μm without intermediate annealing.
After cutting into OC11, diffusion heat treatment was performed at 1200°C in an H atmosphere for 12 hours to obtain a chromium iron alloy.

This chromium alloy was tested in HCI at 30°C for 10
Almost no weight loss was observed in the 0-hour immersion test.

Claims (4)

[Claims] (1) In a method of processing an alloy material that is difficult or virtually impossible to cold-form into a desired product by cold-working, a metal with high ductility and a metal with low ductility are separated from among the metal components constituting the alloy. A metal powder with high ductility and a metal powder with low ductility are prepared by sorting, the prepared metal powder with high ductility and the metal powder with low ductility are mixed to have a target alloy composition, and the mixed powder material is mechanically processed. A powder material with a composite structure in which metal powder with poor ductility is mechanically dispersed in a matrix of a highly ductile metal is obtained by subjecting it to an alloying method, and this powder material with a composite structure is substantially maintained. Preforming a ductile composite structure by applying a sufficient reduction to bond the ductile metals together and/or pre-sintering under conditions that maintain the composite structure. the preform is cold worked with or without intermediate annealing to the shape of the final product, and the workpiece is processed to form a material of sufficient ductile and less ductile metal to form an alloy. A method for manufacturing a processed product of a difficult-to-work alloy, which is characterized by annealing at a temperature and time to obtain a target structure of a difficult-to-work alloy. (2) The metal powder with poor ductility is a powder of a metal element, an alloy powder, or an intermetallic compound powder.
Manufacturing method described in section. (3) The manufacturing method according to claim 1, 2 or 3, wherein the highly ductile metal powder and the less ductile metal powder are fine powders with particle sizes in the range of 0.1 μm to 20 μm. . (4) The ductile metal powder should be at least 4% in the mixed material.
Claims 1 and 2 are in the range of 0% by volume or more.
The manufacturing method described in item 3 or item 3.