JPS62114755A - Production of metallic article - Google Patents

Abstract

PURPOSE:To permit the formation of the finer grains and the control of a splashing direction and to decrease segregation and oxygen content by dropping a molten metal onto a rotary disk which has a collision surface of a smooth surface and a specified height upward on the outside periphery thereof in the position deviated from the center of the disk. CONSTITUTION:The inside of a chamber 1 is evacuated to a vacuum and is replaced with gaseous Ar. An alloy is heated in an electric furnace 2 and is poured into a tundish 3. The molten metal 5 is dropped from an aperture 4 provided in the bottom of the tundish 3 to the position S deviated from the center of rotation of the rotary disk 6. The molten metal 5 is made into the fine particles 8 by the rotary disk 6 and a side wall 7 thereof. THe fine particles 8 deposit and solidify on a moving base body 9 before said particles are not solidified yet. A shape material stock 10 is thus obtd. The wall on the outside periphery of the rotary disk is preferably inclined at 90-135 deg. with the disk plane.

Description

[Detailed description of the invention] <Industrial application field> This invention relates to a method for manufacturing metal articles.

<Prior Art> When manufacturing metal articles, especially molded materials, it is desired that the structure be uniform and fine.

If segregation exists, it will significantly reduce the properties of subsequent processing, such as rolling or forging, and the coarse structure will reduce the strength and
Deteriorates mechanical properties such as elongation.

Conventionally, the melting and casting method has been commonly used as a method for producing shaped materials due to its simplicity, but this method has problems such as coarse grains and segregation. In response to this problem, efforts have been made to obtain a uniform structure by electromagnetic stirring, but the stirring method merely changes the shape of segregation and has not provided a fundamental solution.

On the other hand, with the development of technologies such as CIP and 1-11P, technologies applying powder metallurgy have been developed.

However, although this method also has the advantage of producing a uniform and fine structure compared to the melt casting method, there is an oxide film on the surface of the raw material, and the oxygen content of the formed material is lower than the melt casting method. On the other hand, it is very high, and there is a problem that fatigue properties etc. deteriorate, and high quality cannot be expected.

<Means for solving the problem> However, in the method adopted in this invention, that is, the method of depositing and solidifying molten metal as fine particles, a fine structure with small segregation can be obtained, and the amount of oxygen contained is small. There is an advantage.

The reason for this is that when fine particles in an unsolidified state are deposited and solidified, a process occurs in which the next particle is deposited only after the particles that have landed are completely solidified. No segregation occurs. Therefore, if the particles are very fine, it can be said that there is almost no macro segregation.

When the particles are fine, the cooling rate is high, the microstructure is reduced by 1q, and microsegregation is suppressed.

Therefore, how to make the molten metal into fine particles becomes an important issue. In order to obtain finer particles in an unsolidified state, there are generally two methods: a centrifugal nof using a rotating disk, a micronization method using impact force, and a gas 71-mize method in which gas is blown onto the molten metal. Conceivable. The rotating disk method has the advantage of being able to obtain fine particles at a lower cost than the gas atomization method, but in order to achieve this, it is necessary to attach protrusions to the disk surface to efficiently transmit centrifugal force and impact force. , or the disk rotation speed must be very fast.

However, since the former method makes it impossible to control the direction of the scattered particles, it is necessary to use a rotating disk without protrusions.

When the latter disk with a smooth surface without protrusions is used, the high speed rotation f of 100 (10 rl) 111 or more is used.
It is difficult to obtain fine particles without using a disk, and the structure of the device must be rigid and complex.

<Structure of the Invention> As described in detail above, when molten metal is generally made fine by using a rotating disk, it is extremely difficult to make the particles fine and to control the scattering direction of the particles.

In response, the present inventors have developed a method that can solve the two problems at the same time, that is, by applying two large impacts with one rotating disk, the particles are made finer and the scattering direction of the particles is controlled. I found a possible method.

That is, the present invention provides a rotating disk having a collision surface that is smooth enough to prevent molten metal from adhering or solidifying, and a wall of a certain height above the outer periphery of the rotating disk. The molten metal is flowed down to achieve fineness and to control the scattering direction of the particles.

According to the method of this invention, the flowing molten metal is first atomized by the centrifugal force and impact force from the rotating disk. The finely divided particles collide with the outer peripheral wall of the disk, where they are subjected to large impact horns and centrifugal force, becoming finer particles and oriented to the outside of the rotating disk in an unsolidified state. scatter.

At this time, the grain size to be refined is d, the disk radius is D,
Letting the disk rotation speed be ω, there must be the relationship 1/2 −nd=c[)−ω (where O≦rl≦1>−(1).

When 100% of the centrifugal force from the rotating disk is transmitted to the molten metal, n=1, and the decrease in transmission efficiency is worth the decrease in the value of n.

When the surface of the rotating disk is smooth, it is naturally assumed that the value of n will be small, and the particle diameter d will not easily become small. Therefore, by creating a wall around the outer periphery of the rotating disk and creating a shape that allows for efficient transmission of centrifugal force, we were able to increase the value of n and give the particles directionality. is.

Here, the wall of the outer periphery of the rotating disk is ′C relative to the disk surface.
The inclination angle is preferably 90 to 135 degrees. This is because when the angle is less than 90 degrees, particles that collide with the wall return onto the rotating disk and do not fly out of the disk. Also, if the angle is greater than 135 degrees, the centrifugal force will not be transmitted efficiently.

According to this invention, the particles are characterized by either continuously changing direction on the rotating disk or moving in a discontinuous direction (tangential direction) on the side wall, and the velocity is discontinuous. A large impact will be applied at the point.If the side wall is at an angle of 135 degrees or more, no large impact will be applied, making it difficult for micronization to occur.

Metal articles are manufactured by counting the number of unsolidified particles that fly outside the rotating disk in this manner.

<Example> Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 is an external view of an apparatus for carrying out the method of the present invention. The inside of the chamber 1 was evacuated using a vacuum device (not shown) and replaced with Ar gas. Next, in an electric furnace 2, M-19,1%5i-0,6%Fe-4,5%Ctt-
0.8%I'In-0.4%Mg-0,8%Cr-0,
2% ZTI A & gold alloy its melting point 250~300
It was heated to a high temperature and poured into Tanditshu 3.

Then, the molten metal 5 flows down from the opening 4 with a diameter of about 1# provided at the bottom of the tundish 3 to a position @S that is 70# eccentric from the center of rotation of the rotating disk 6, and the fine particles 8 and this fine particle 8
While in an unsolidified state, the mixture was deposited on the moving substrate 9 and solidified to obtain a formed material 10.

FIG. 2 shows the theoretical and experimental values of the relationship between the number of rotations of the rotating disk and the particle size. Curve A in the figure is an experimental value when a flood disk is used, curve B is a theoretical value when 100% centrifugal force is transmitted using flanno disks with the same surface roughness, and curve C is a theoretical value when 100% of the centrifugal force is transmitted. These are experimental values when using a rotating disk.

As can be seen from the curve Δ, when the rotating disk surface was smooth, the centrifugal force transmission efficiency was poor, and was approximately n÷0.3. Curve B is the theoretical value when using the same rotating disk, but at 6000 ppm, the theoretical value is d + 330 μ
Since the experimental value of m1 is 720 μm, it can be seen that the experimental value is quite poor.

Curve C is due to the rotating disk of this invention, and due to the smooth disk surface, the particles are refined to the size shown by curve A before colliding with the side wall, and are again subjected to large centrifugal force and impact force on the side wall ( This is because the particles are miniaturized.

According to the above-mentioned equation (1), n÷0.8 was obtained for the side wall. In addition, we succeeded in creating an epoch-making disk that exceeds the theoretical value that assumes 100% centrifugal force transmission efficiency when miniaturizing a single rotating disk.

<Effects of the Invention> As described above, according to the method of the present invention, centrifugal force 7J can be effectively transmitted to the molten metal, and fine particles can be directionally scattered in an unsolidified state by low-speed rotation. It is possible to use extremely simple equipment at a low cost of 1~
It has great industrial utility value as it can be produced in

[Brief explanation of drawings]

FIG. 1 is an external sectional view of an apparatus used in the method of the present invention, and FIG. 2 is a diagram showing the relationship between the rotational speed of a rotating disk and the particle size of scattered particles. 1...Chamber 2...Electric furnace 3...
・Tandish 4... Opening 5... Molten metal 6... Rotating disk 7... Side wall
8... Fine particles 9... Moving base
10...Representative of the material applicant Patent attorney Kazu 1) Showu-v, Particle size (mm) 〉 Aken

Claims (1)

[Claims] In the production of metal articles having a fine structure, in which molten metal is turned into fine particles by the impact force and centrifugal force of a rotating disk, and is deposited and solidified in an unsolidified state, the shape of the rotating disk is the same as that of the rotating disk collision surface and its outer periphery. 90 upwards
It has walls of a certain height that are inclined at an angle between 135 degrees and 135 degrees.The molten metal is first flowed down onto the collision surface that is off the center of rotation of a rotating disk of the shape, and the impact force and centrifugal force After the fine particles are made into fine particles, they are made to fly and collide with the wall in a direction on the collision surface, thereby further making the particles finer, and scattering them in a directionally manner to the moving substrate in an unsolidified state. A method for manufacturing a metal article, characterized by depositing and solidifying it.