JP3496833B1 - Method for producing metallic material in solid-liquid coexistence state - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To obtain finer spheroidized particles and at the same time to improve energy efficiency, reduce production cost, improve mechanical properties,
Provided is a method for producing a metal material in a solid-liquid coexistence state, which can realize advantages of simplifying a casting process and shortening a production time. SOLUTION: After applying an electromagnetic field and pouring molten metal into the container, the application of the electromagnetic field to the container is terminated. The molten metal poured into the container is cooled to form a solid-liquid coexisting metal material. In the step of cooling the molten metal, the temperature is uniformly reduced from the wall surface of the container to the central portion without generating latent heat due to the formation of the initial solidified layer. 1 after pouring of molten metal
The molten metal can be rapidly cooled to the liquidus temperature or less within a short time of about 10 seconds to about 10 seconds, and a large number of crystal nuclei can be uniformly generated over the entire area. A metal material having a fine and uniform structure can be manufactured.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a method for producing a solid-liquid coexisting state metal materials for cooling from application of electromagnetic field in the molten metal.

[0002]

2. Description of the Related Art A so-called semi-solidification or semi-melting processing method for processing a solid-liquid coexisting metal material is a composite processing method in which casting and forging are mixed. It can be roughly divided. The semi-solid forming method is a processing method of directly forming a metal slurry produced in a semi-solid state to produce a final product. The semi-melt forming method is a processing method in which a billet is manufactured in a semi-solidified state, and then the billet is reheated to a semi-molten state and forged or die-casted to manufacture a final product.

A metal slurry for semi-solidification or semi-melt forming can be deformed by a small force due to its thixotropic property in a state where a liquid phase and spherical crystal grains are mixed in an appropriate ratio at a temperature in a semi-solidification region, Excellent liquidity and liquid phase (thixo
(tropic) is a metal material that can be easily processed. Since the billet can recover the semi-molten state of the metal slurry form by reheating, it is very usefully used as a metal material for semi-solidification or semi-melt forming.

The semi-solidification or semi-melt forming method using a metal slurry or billet has various advantages as compared with the case of using a liquid metal alloy having the same composition. For example, in the field of metal forming, metal slurries have fluidity at temperatures below that required for complete melting of liquid metal alloys, thus lowering the die die exposure temperature, thus extending die life. In addition, turbulent flow does not occur when the metal slurry is extruded, air is less mixed in the casting process, and pores can be prevented from being generated in the final product. Therefore, heat treatment is possible and the mechanical properties can be greatly improved. Besides, solidification shrinkage is small, workability and corrosion resistance are improved, and the weight of the product can be reduced. Therefore, it can be used as a new material for the fields of automobiles and aircrafts, electrical and electronic information communication equipment.

In the conventional method for producing a semi-solid alloy, the dendrite structure that has already been produced is crushed by stirring the molten metal mainly at a temperature below the liquidus line so that the semi-solid alloy has a spherical shape suitable for semi-solid forming. It is a method to make particles. Mechanical stirring method and electromagnetic stirring method, gas bubbling, low frequency,
A high frequency or electromagnetic wave vibration was used, or a stirring method by electric shock was used.

As a method for producing a liquid-solid mixture, the alloy is heated to a temperature at which most of the alloy exists in the liquid phase, and then the formed molten metal is cooled with vigorous stirring. Solid content in molten metal is 40% or more 65
Cool while continuing to stir until it reaches less than 100%. At this time, a solid-liquid mixture is produced by preventing the formation of a dendrite structure, or by removing or reducing the dendrite structure already formed on the primary solid particles (for example, Patent Document 1). reference.).

Further, as a method for producing a semi-solid alloy slurry, the molten metal is electromagnetically mixed by a moving magnetic field provided over the entire range of the solidification region in the container containing the molten metal. In this method, the magnetic field causes the dendrite structure formed in the solidified region to be sheared at a predetermined shear rate (see, for example, Patent Document 2).

Further, as a method for producing a semi-molten molded material, after heating the alloy so that all the metal components in the alloy exist in the liquid phase, the resulting liquid metal is placed between the liquidus line and the solidus line. Cool to temperature. Thereafter, a semi-molten molded material is produced by crushing a dendrite structure formed from molten metal that is cooled by applying a shearing force (for example,
See Patent Document 3. ).

As a method for producing a metal slurry for semi-solid casting, molten metal is poured into a container at a temperature near the liquidus temperature or up to 50 ° C. higher than the liquidus temperature. After that, when at least a part of the molten metal falls below the liquidus temperature in the process of cooling the molten metal, that is, when the molten metal first passes the liquidus temperature, the molten metal is moved by, for example, ultrasonic vibration. Add. Further, after exercising the molten metal, it is gradually cooled to produce a metal slurry for semi-solid casting having a metal structure of a grain phase crystal form (see, for example, Patent Document 4).

That is, by applying an appropriate motion to the molten metal in the vicinity of the liquidus line, the dendritic crystal structure which is thought to be formed in each initial crystal nucleus initially formed is crushed, and each particle is initially crushed. Gradient phase crystal morphology is obtained by gradually cooling in the state of independently existing without interaction between crystal nuclei. Also in this method, a force such as ultrasonic vibration is used to crush the dendrite structure formed in the initial stage of cooling. Further, if the pouring temperature is set to a level higher than the liquidus temperature, it is difficult to obtain a granular crystal form and it is difficult to rapidly cool the molten metal. Furthermore, the texture of the surface portion and the central portion becomes non-uniform.

Further, as a method of forming the semi-molten metal,
After pouring the molten metal into the container, the vibration bar is immersed in the molten metal and vibrated in a state of being in direct contact with the molten metal to vibrate the molten metal. Specifically, after the molten metal is first poured into the container, the vibration bar is immersed in the molten metal to transmit the vibration force to the molten metal. As a result, a liquid-state alloy having crystal nuclei at a liquidus temperature or higher or a solid-liquid coexisting state having crystal nuclei at a temperature below the liquidus temperature and higher than the molding temperature is formed. After that, while maintaining the molten metal in the container for 30 seconds to 60 minutes while cooling the molten metal to a forming temperature showing a predetermined liquid phase ratio, fine crystal nuclei grow in the alloy to obtain a semi-molten metal. . However, the size of the crystal nuclei obtained by this method is about 100 μm, the process time is considerably long, and it is difficult to apply it to a container having a predetermined size or more (for example, refer to Patent Document 5).

As a method for producing the semi-molten metal slurry, the semi-molten metal slurry is produced by simultaneously precisely controlling cooling and stirring. Specifically, after pouring the molten metal into the mixing container, a stator assembly installed around the mixing container is operated to generate a magnetic force sufficient to rapidly agitate the molten metal in the container. Further, the temperature of the molten metal is rapidly lowered by utilizing a thermal jacket provided around the mixing vessel and serving to precisely control the temperature of the vessel and the molten metal. When the molten metal is cooled, the molten metal is continuously stirred, and when the solid fraction is low, the molten metal is rapidly stirred, and the electromotive force is increased as the solid fraction is increased (see, for example, Patent Document 6). .).

[0013]

[Patent Document 1] US Pat. No. 3,948,650 (Column 3-8, FIG. 3)

[0014]

[Patent Document 2] US Pat. No. 4,465,118 (column 4-12, FIG. 1, FIG. 2, FIG. 5 and FIG. 6)

[0015]

[Patent Document 3] US Pat. No. 4,694,881 (columns 2-6)

[0016]

[Patent Document 4] Japanese Patent Application Laid-Open No. 11-33692 (No. 3-
(Page 5, Figure 1)

[0017]

[Patent Document 5] Japanese Unexamined Patent Publication No. 10-128516 (4th
(P.7, Fig. 3)

[0018]

[Patent Document 6] US Pat. No. 6,432,160 (col. 7-15, FIGS. 1A to 2B and FIG. 4)

[0019]

As described above, in the above-mentioned conventional technique, the shearing force is mostly used to pulverize the dendrite morphology already formed during the cooling process into a metallic structure of a granular phase. Are using the method. Therefore, when at least a part of the molten metal falls below the liquidus line, a force such as vibration is applied, and various problems such as a decrease in cooling rate and an increase in manufacturing time due to the generation of latent heat due to the formation of the initial solidified layer are avoided. Hateful. If the temperature of the molten metal poured into the container is not adjusted, it is difficult to prevent the formation of the dendrite structure of the initial solidified layer near the wall surface due to the temperature difference between the wall surface of the container and the center. The hot water temperature and cooling process must be precisely controlled.

The present invention has been made in view of the above points, and at the same time obtains finer spheroidized particles, improves energy efficiency, saves manufacturing cost, improves mechanical properties, simplifies the casting process, and and to provide a manufacturing method of the solid-liquid coexisting state metal materials that can realize the benefits of reduced manufacturing time.

[0021]

According to the method for producing a solid-liquid coexisting state metal material of the present invention, molten metal poured into a container is melted.
An applying step of applying an electromagnetic field that does not form an initial solidified layer in the, and a pouring step of pouring molten metal into the container in a state where the electromagnetic field is applied to the container in this applying step, and the melting And a cooling step of cooling the molten metal after the application of the electromagnetic field to form a metal material in a solid-liquid coexisting state. It was done.

Since there is almost no temperature difference between the center and the wall of the container containing the molten metal and between the upper part and the lower part, the temperature of the molten metal in the container is uniform, Since the latent heat due to the initial solidification in a specific region is not generated, the molten metal can be cooled rapidly in a short time.
Therefore, it is possible to reduce the size of the spherical particles by remarkably increasing the crystal nucleus generation density of the molten metal.

[0023] Further , the tree branches in the molten metal poured into the container
A step of applying an electromagnetic field that does not form a crystal-like crystal,
In this applying step, the electromagnetic field is applied to the container
A pouring step of pouring molten metal into the container in a state where
Of the electromagnetic field to the container where the molten metal is poured
The end process of ending the application and the end of the application of the electromagnetic field
The molten metal is cooled to form a metal material in the solid-liquid coexisting state.
And a cooling step to be performed.

Further, marking for applying an electromagnetic field to the container
In the applying step, the electromagnetic field is applied to the container.
Pouring machine for pouring molten metal into the container while being heated
And when the temperature of the molten metal reaches near the liquidus
In the electromagnetic field for the container where the molten metal is poured,
End process to end the application of the field and end the application of the electromagnetic field
Material in a solid-liquid coexisting state by cooling the molten metal
And a cooling step for forming.

Furthermore, a mark for applying an electromagnetic field to the container
In the applying step and the applying step, the electromagnetic field is applied to the container.
Pouring molten metal into the container while it is being applied
At the hot water process and at the time when crystal nuclei are generated in the molten metal,
Of the electromagnetic field to the container where the molten metal is poured
The end process of ending the application and the end of the application of the electromagnetic field
The molten metal is cooled to form a metal material in the solid-liquid coexisting state.
And a cooling step to be performed.

In the ending step, it is desirable to end the application of the electromagnetic field in the applying step when the solid phase ratio of the molten metal becomes 0.001 or more and 0.1 or less.

Further, the metal material is either a metal slurry or a billet.

In the pouring process, the temperature of the molten metal during pouring is higher than the liquidus temperature of the molten metal, and the liquidus line +
It is desirable that the temperature is lower than 100 ° C.

Further, a secondary forming step of secondary forming a solid-liquid coexisting metal material is provided, and the secondary forming step is any one of die casting, molten metal forging, forging and pressing.

Further, a reheating step of reheating the billet-shaped metal material to a solid-liquid coexisting state for secondary molding is provided.

Further, in the cooling step, it is desirable to cool until the solid phase ratio of the molten metal becomes 0.1 or more and 0.7 or less.

In the cooling step, the molten metal is heated to 0.2 ° C. /
It is desirable to cool at a rate of not less than sec and not more than 5 ° C./sec.

Further, in the cooling step, the molten metal is heated to 0.2 ° C.
It is more desirable to cool at a rate of not less than / sec and not more than 2 ° C / sec.

The molten metal is aluminum, aluminum alloy, magnesium, magnesium alloy, zinc,
It is one of zinc alloy, copper, copper alloy, iron and iron alloy .

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

First, before the pouring step of pouring the molten metal into the container, an electromagnetic field is applied to the container in the applying step, and the molten metal is poured into the container in this state. Ultrasonic waves may be used instead of the electromagnetic field. Any applicable metal can be used as long as it can be used for solid-liquid coexisting state molding, so-called semi-solidification or semi-melt molding, and among them, a group consisting of aluminum, magnesium, copper, zinc, iron and alloys thereof. It is desirable to be selected from These alloys may contain various optional metals depending on the physical properties required in the final molded product.

At the time of pouring the molten metal into the vessel, the temperature of the molten metal is higher than the liquidus temperature and lower than the liquidus line of this molten metal + 100 ° C (molten metal superheat degree = 0 ° C or higher and 100 ° C or higher).
It is desirable that the temperature be maintained below (° C). That is, since the entire container containing the molten metal is cooled uniformly, it is not necessary to cool the molten metal to near the liquidus temperature before pouring the molten metal into the container. It doesn't matter if you keep

On the other hand, in the conventional method of applying an electromagnetic field to the container when the molten metal is poured into the container and a part of the molten metal becomes below the liquidus line, an initial solidified layer is formed on the wall surface of the container. While the latent heat of solidification is generated while the latent heat of solidification is about 400 times the specific heat, it takes a long time for the temperature of the molten metal in the entire container to drop. Therefore, in such a conventional method, it is general that the temperature of the molten metal is cooled to about the liquidus or about 50 ° C. higher than the liquidus, and then the molten metal is poured into the container.

Further, by pouring the molten metal into the container in a state where an electromagnetic field is applied to the container, there is almost no temperature difference between the wall surface and the center of the container where the molten metal is poured, and between the upper part and the lower part. Absent. Therefore, the initial solidification in the vicinity of the wall surface of the container, which occurs in the conventional technique, does not occur, and the entire molten metal in the container can be uniformly and rapidly cooled immediately below the liquidus temperature to generate a large number of crystal nuclei at the same time. . In addition, the reason why the temperature difference does not occur over the entire container in this way is that the electromagnetic field is already applied to the container at the time of pouring the molten metal into the container, and therefore the internal molten metal is generated by the active initial stirring action. This is because the molten metal on the surface is well agitated, the heat transfer is rapidly performed in the molten metal, and the formation of the initial solidified layer on the inner wall of the container is suppressed. Further, the convective heat transfer between the well-stirred molten metal and the inner wall of the low temperature container is increased, so that the temperature of the entire molten metal can be rapidly cooled in the cooling step. That is, the molten metal poured into the container becomes dispersed particles by stirring the electromagnetic field at the same time as the molten metal is poured, and the dispersed particles are uniformly distributed in the container as crystal nuclei, so that no temperature difference occurs throughout the container. . on the other hand,
According to the prior art, the molten metal poured into contact with the inner wall of the low-temperature container, and rapid convective heat transfer causes the dendrites to grow in the initial solidified layer.

Then, the principle can be explained in relation to the latent heat of solidification. That is, since the initial solidification of the molten metal on the wall surface of the container does not occur and the latent heat of solidification does not occur, the cooling of the molten metal corresponds to the specific heat of the molten metal (only about 1/400 of the latent heat of solidification). It is possible only by releasing the heat of.
Therefore, the conventional technique does not form dendrites, which are the initial solidification layer that often occurs on the wall surface of the container, and the molten metal in the container is uniformly and rapidly heated from the wall surface to the center of the container. Shows a drop. The time required to lower the temperature at this time is about 1 after pouring the molten metal.
It's just a short time of more than 10 seconds and less than 10 seconds. This allows
A large number of crystal nuclei are uniformly generated throughout the molten metal in the container, and the distance between the crystal nuclei becomes very short due to the increase in the crystal nucleation density, so that dendrites do not form and grow independently and become spherical. Form particles.

The application of the electromagnetic field in the applying step ends in the ending step when the temperature of the molten metal in the container reaches the vicinity of the liquidus line. At the end of application of the electromagnetic field, the solid phase ratio of the molten metal in the container is preferably 0.001 or more and 0.1 or less. Furthermore, the solid fraction is at a predetermined level, that is, about 0.1.
When, the crystal nucleation is completed. At this point, the application of electromagnetic field to the container is terminated. It is not desirable in terms of energy efficiency to continue applying the electromagnetic field even in the state where the solid phase ratio is 0.1 or more, and it is not desirable because the solidified structure is coarsened and the process time is extended.

After the application of the electromagnetic field to the container is finished, the molten metal is cooled in the cooling step until the solid phase ratio reaches a predetermined solid phase ratio, preferably 0.1 to 0.7.

The cooling rate of the molten metal in this cooling step is preferably 0.2 ° C./sec or more and 5.0 ° C./sec or less, and the cooling rate is 0 in terms of the distribution of crystal nuclei and the fineness of particles. More preferably, it is not less than 0.2 ° C./sec and not more than 2.0 ° C./sec.

According to the above-mentioned one embodiment, the time required from the time of pouring the molten metal into the container to the time of forming the metal material in the form of a metal slurry having a solid fraction of 0.1 or more and 0.7 or less. It is no less than 30 seconds and no more than 60 seconds. The metal slurry can be manufactured as a billet through rapid cooling.

Further, the metal slurry or billet-shaped metal material can be subjected to a secondary molding step such as die casting, molten metal forging, forging, and pressing in the secondary molding step. The billet-shaped metallic material can be cut into an appropriate length to form a slag, and the slag is restored to a semi-molten state through reheating by a reheating process for secondary molding.

Further, the metal particles contained in the manufactured metal material for semi-solidification or semi-melt molding are fine spherical particles having an average particle size of 10 μm or more and 60 μm or less, and the particle size distribution is uniform.

[0047]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 First, in Example 1, an aluminum alloy A356 alloy was used as an alloy material for the molten metal. 500g
The A356 alloy is heated in an electric furnace (10 kW) in a graphite crucible at about 750 ° C. for 1 hour to be melted, and the molten metal is shielded by a shield type thermocouple (K The temperature of the molten metal was maintained at about 100 ° C. or lower than the liquidus temperature of the molten metal (about 615 ° C. in the case of A356 alloy) by measuring the temperature.

FIG. 1 shows a work process diagram according to the first embodiment.

In applying an electromagnetic field to the container, the voltage, frequency and intensity of the electromagnetic field stirring device (EMS: device itself manufactured) were fixed at 250 V, 60 Hz and 500 gauss, respectively. Before the molten metal is poured into the container, the molten metal is supplied to the container when the temperature of the molten metal reaches 650 ° C (Tp: pouring temperature in Fig. 1) while the power is supplied to the EMS and the EMS is operated. I poured water.

After the molten metal was poured into the container in a state where the electromagnetic field stirring motion was previously applied to the container, when the temperature of the molten metal reached near the liquidus line (point a in FIG. 1), E
The MS was turned off. That is, the EMS was operated only in the section p in FIG. After stopping the operation of the EMS, the molten metal is cooled at a cooling rate of 1 ° C./sec until the solid phase ratio reaches 0.6 (point b in FIG. 1, the temperature at this time is about 586 ° C.). A metal slurry was obtained. It took about 40 seconds from the time when the molten metal was poured into the container to the solid phase ratio of 0.6.

Thereafter, a secondary forming process is performed, that is, after the point b in FIG. 1, a secondary forming step such as die casting, molten metal forging, forging or pressing is performed.

Specimens were obtained by the following method in order to observe the metal structure of the metal material manufactured by the method of Example 1. First, a billet was manufactured by rapidly cooling a metal slurry. The billet is cut using a band saw to obtain a cut piece, which is then polished to obtain a Keller solution (2
0 ml H ₂ O + 20 ml HCl + 20 ml HNO
After etching using ₃ + 5 ml of HF), it was used as a test piece for image analysis, and
The metallographic structure was observed using a nalyzer: LEIC ADMR). The result is shown in FIG. As shown in FIG. 2, according to Example 1, it is possible to obtain a metal material having a uniform and fine spherical particle structure over the surface portion and the central portion.

<Example 2-5> The same method as in Example 1 was carried out, but the temperature of the solution metal when pouring the molten metal into the container was 720 ° C (Example 2) and 700, respectively.
C. (Example 3), 650.degree. C. (Example 4) and 620.degree. C. (Example 5), and when the solid fraction of the molten metal reaches 0.05 (immediately above the liquidus temperature), the operation of the EMS is stopped. Solid phase ratio 0.6
Then, it was rapidly cooled to produce a billet. It took less than 1 minute to complete the process. After producing a sample for the billet thus obtained in the same manner as in Example 1, the metal structure was observed. Image analysis photographs of the specimens obtained in Examples 2 to 5 are shown in FIGS. 3 to 6.

As shown in FIGS. 3 to 6, 72
Even when the molten metal pouring temperature was changed within the temperature range of 0 ° C. or higher and 620 ° C. or higher, a fine and uniform alloy (spherical particles having an average particle size of 30 μm or more and 60 μm or less) was produced. Therefore, according to these Examples 2 to 5, the spheroidized structure can be obtained even in a short time of less than 1 minute. This is because the spacing between the initial crystals is significantly shortened due to the significant increase in the nucleation density, and the shape of the structure can be maintained constant even with faster cooling than the conventional method.

Example 6-9 The same method as in Example 1 was carried out, but the cooling rate at the time of cooling the molten metal after the application of the electromagnetic field was completed was 0.2 ° C./sec (Example 6). ), 0.4 ° C./sec (Example 7), 0.6 ° C./sec (Example 8) and 2.0 ° C. /
After obtaining a metal slurry as sec (Example 9), it was rapidly cooled to produce a billet. Example 1 for these billets
The metallographic structure was observed after the specimen was manufactured by the same method.
The results are shown in FIGS. 7 to 10.

As shown in FIGS. 7 to 10, the metal structure obtained by varying the cooling rate in the cooling process of the molten metal is spherical. Further, the particles of the metal structure are fine with an average particle size of 10 to 60 μm, and the distribution of spherical particles is uniform.

<Examples 10 to 13> The same method as in Example 1 was carried out, but the temperature at the end of cooling was changed in cooling the molten metal after the application of the electromagnetic field was completed. The temperature of the molten metal at the end of this cooling was 610 ° C. (Example 10: solid fraction is about 0.2),
600 ° C (Example 11), 590 ° C (Example 12), 586
This was the time when the temperature reached ℃ (Example 13: the solid fraction was about 0.6).
A test piece was manufactured by the same method as in Example 1, and the metal structure of the test piece was observed. The results are shown in FIGS. 11 to 14.

As can be seen from the photographs of the metal structures shown in FIGS. 11 to 14, the metal of the alloy obtained by variously changing the cooling end time in the cooling step of the molten metal after the electromagnetic field stirring is completed. The structure is fine and the distribution of spherical particles is uniform. That is, according to these tenth to thirteenth examples, when the molten metal was poured into the container in a state where the electromagnetic field stirring was added to the container in advance and the electromagnetic field stirring was completed near the liquidus, Even if changed, there is almost no difference in the metallographic structure of the obtained alloy.

Example 14 The same method as in Example 1 is carried out, but the pouring temperature is 650 ° C.
After the application of the electromagnetic field was completed, the molten metal was cooled at a cooling rate of 1.5 ° C./sec until the solid fraction reached 0.6. The time required to reach the solid phase ratio of 0.6 after pouring the molten metal was 35 seconds. A test piece was manufactured by the same method as in Example 1, and the metallographic structures on the surface portion and the central portion of the test piece were observed. The results are shown in FIGS. 15 and 16.

Example 15 The same method as in Example 1 was carried out, but after the molten metal was poured into the container at a temperature of 700 ° C. and the application of the electromagnetic field was completed, the solid phase ratio reached 0.6. The molten metal was cooled at a cooling rate of 1.5 ° C / sec. The time required to reach the solid phase ratio of 0.6 after pouring the molten metal was 40 seconds. A sample was manufactured by the same method as that described in Example 1, and the metallographic structures of the surface and the center of the sample were observed. The results are shown in FIGS. 17 and 18.

Comparative Example 1 For comparison, the same method as in Example 14 was carried out, but after pouring the molten metal into the container, the EMS was operated immediately below the liquidus temperature for about 10 seconds, It was cooled at a rate of 8 ° C./sec until the solid phase ratio of the molten metal reached about 0.6. The time required to reach a solid fraction of 0.6 after pouring the molten metal was 75 seconds. A test piece was manufactured by the same method as in Example 1 and the metallographic structure was observed. The results are shown in FIGS. 19 and 20.

Comparative Example 2 For comparison, the same method as in Example 15 was carried out, but after pouring the molten metal into the container, the EMS was operated immediately below the liquidus temperature for about 10 seconds to: 1. It was cooled at a rate of 0 ° C./sec until the solid phase ratio of the molten metal reached about 0.6. The time required to reach a solid fraction of 0.6 after pouring the molten metal was 85 seconds. A sample was manufactured by the same method as in Example 1 and the metallographic structure was observed. The results are shown in FIGS. 21 and 22.

Comparing the results of Examples 14 and 15 with the results of Comparative Examples 1 and 2, the metal materials obtained in these Examples 14 and 15 show that the metal particle structures of the surface portion and the central portion are uniformly spherical. The average particle size of the metal particles is uniform and fine over the surface portion and the central portion, while the molten metal was poured into the container by the conventional method in Comparative Examples 1 and 2, and the temperature was below the liquidus line. When the magnetic field stirring force is applied, the central part shows a spherical grain structure,
Since the surface portion exhibits a dendritic structure, the metal structure between the surface portion and the central portion of the metal material is not uniform. Furthermore, the manufacturing time of the metal material for semi-solidification or semi-melting molding was greatly shortened. This is because an increase in the initial crystal nucleus generation density of the molten metal in the container can reach a predetermined solid phase ratio even in a short period of crystal nucleus growth.

As can be seen from the above-mentioned Examples and Comparative Examples, the molten metal container pouring temperature can be raised up to a temperature as high as about 100 ° C. above the liquidus line, and a fine alloy can be produced by a short electromagnetic field stirring. In addition, the time required for producing a metal material for semi-solidifying or semi-melt forming in the form of metal slurry or billet can be significantly shortened, and the metallurgical structure of the obtained alloy shows the morphology of fine spherical particles.

In each of the above-mentioned embodiments, the case where the commercial A356 alloy is manufactured into the metal material for semi-solidifying or semi-melt forming is described, but the present invention is not limited to the above-mentioned manufacturing of the A356 alloy, and various other metals. Or alloys such as aluminum or its alloys, magnesium or its alloys, zinc or its alloys, copper or its alloys,
Alternatively, it can be generally applied to the production of iron or its alloys.

[0067]

EFFECTS OF THE INVENTION According to the method for producing a solid-liquid coexisting state metal material of the present invention, the peripheral portion and the central portion, and the upper and lower portions of the molten metal in the container are spread without the generation of latent heat of solidification due to the formation of the initial solidification layer. By cooling the entire region to near the liquidus temperature, the nucleation density can be markedly increased and spheroidizing of the particles can be realized, and a uniform and fine spherical particle distribution can be realized and the mechanical properties of the alloy can be improved. It is possible to realize the improvement of properties.

Further, since the manufacturing process is simple and the control of the process is easy, and the stirring time of the electromagnetic field can be greatly shortened, the energy required for stirring is less consumed and the molding time of the product is shortened, which is economical. There are also considerable advantages.

[Brief description of drawings]

FIG. 1 is a process drawing showing a method for producing a solid-liquid coexisting state metal material according to an embodiment of the present invention.

FIG. 2 is a photograph showing the structure of a metal material produced by the method for producing a solid-liquid coexisting state metal material according to the above.

FIG. 3 is a photograph showing the structure of a metal material produced by changing the molten metal container pouring temperature in the method for producing a solid-liquid coexisting state metal material.

FIG. 4 is a photograph showing the structure of a metal material produced by changing the molten metal container pouring temperature in the method for producing a solid-liquid coexisting state metal material.

FIG. 5 is a photograph showing the structure of a metal material produced by changing the molten metal container pouring temperature in the method for producing a solid-liquid coexisting state metal material.

FIG. 6 is a photograph showing the structure of a metal material produced by changing the temperature of molten metal poured in a container by the method for producing a solid-liquid coexisting state metal material.

FIG. 7 is a photograph showing the structure of a metal material produced by changing the cooling rate of the molten metal in the same method for producing a solid-liquid coexisting state metal material.

FIG. 8 is a photograph showing the structure of a metal material produced by changing the cooling rate of molten metal in the method for producing a solid-liquid coexisting state metal material.

FIG. 9 is a photograph showing the structure of a metal material produced by changing the cooling rate of molten metal in the same method for producing a solid-liquid coexisting state metal material.

FIG. 10 is a photograph showing the structure of a metal material produced by changing the cooling rate of the molten metal in the same method for producing a solid-liquid coexisting state metal material.

FIG. 11 is a photograph showing the structure of a metal material produced by changing the completion time of cooling of molten metal in the same method for producing a solid-liquid coexisting state metal material.

FIG. 12 is a photograph showing the structure of a metal material produced by changing the completion time of cooling of molten metal in the same method for producing a solid-liquid coexisting state metal material.

FIG. 13 is a photograph showing the structure of a metal material produced by changing the cooling completion time of the molten metal in the same method for producing a solid-liquid coexisting state metal material.

FIG. 14 is a photograph showing a structure of a metal material produced by changing the time when the cooling of the molten metal is completed in the same method for producing a solid-liquid coexisting state metal material.

FIG. 15 is a photograph showing a texture of a surface portion of a metal material manufactured according to another embodiment of the present invention.

FIG. 16 is a photograph showing the structure of the central part of the above metal material.

FIG. 17 is a photograph showing a texture of a surface portion of a metal material manufactured according to another embodiment of the present invention.

FIG. 18 is a photograph showing the structure of the central part of the same metal material.

FIG. 19 is a photograph showing a structure of a surface portion of a metal material manufactured by a conventional semi-solidification molding method.

FIG. 20 is a photograph showing the structure of the central part of the above metal material.

FIG. 21 is a photograph showing a structure of a surface portion of a metal material manufactured by another conventional semi-solidification molding method.

FIG. 22 is a photograph showing the structure of the central part of the above metal material.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayuki Itamura 316-78 Nishikinami, Ube City, Yamaguchi Prefecture (56) Reference JP-A-5-237611 (JP, A) JP-A-4-279250 (JP , A) JP-A-8-187547 (JP, A) JP 2000-514717 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B22D 27/02 B22D 1/00 B22D 11 / 00 B22D 27/04 B22D 27/20

Claims (14)

(57) [Claims] 1. An initial solidification layer is formed on a molten metal poured into a container.
And applying step of applying an electromagnetic field which does not form a pouring step of pouring the molten metal in a state in which the electromagnetic field in the vessel at the application step is applied to the container, the molten metal pouring And a cooling step of cooling the molten metal after the application of the electromagnetic field to form a metal material in a solid-liquid coexisting state. And a method for producing a solid-liquid coexisting state metal material. 2. Dendritic formation in the molten metal poured into a container
An applying step of applying an electromagnetic field that does not form crystals , a pouring step of pouring molten metal into the container while the electromagnetic field is being applied to the container in this applying step, and the molten metal pouring And a cooling step of cooling the molten metal after the application of the electromagnetic field to form a metal material in a solid-liquid coexisting state. A method for producing a characteristic solid-liquid coexisting metal material. 3. An applying step of applying an electromagnetic field to the container, a pouring step of pouring molten metal into the container while the electromagnetic field is being applied to the container in the applying step, and the melting step. When the temperature of the metal reaches the vicinity of the liquidus line, the ending step of ending the application of the electromagnetic field to the container in which the molten metal is poured, and the melting step after the application of the electromagnetic field is completed. A method for producing a solid-liquid coexisting state metal material, comprising a cooling step of cooling a metal to form a solid-liquid coexisting state metal material. 4. An applying step of applying an electromagnetic field to the container, a pouring step of pouring molten metal into the container in a state where the electromagnetic field is applied to the container in the applying step, and the melting step. When crystal nuclei are generated in the metal, an end step of ending the application of the electromagnetic field to the container in which the molten metal is poured, and a step of cooling the molten metal after the application of the electromagnetic field to solid-liquid A method for producing a solid-liquid coexisting state metal material, comprising a cooling step of forming a coexisting state metal material. 5. The solid phase ratio of the molten metal is 0.0 in the finishing step.
01 0.1 claims 1 to, characterized in that to terminate the application of the electromagnetic field by applying step when it becomes less
4. The method for producing a solid-liquid coexisting state metal material as described in 4 above. 6. A metallic material claims 1 to characterized in that either metal slurry and billets shape 5
The method for producing a solid-liquid coexisting state metal material according to any one of the above. 7. In the pouring step, the temperature at the time of pouring the molten metal is higher than the liquidus temperature of the molten metal, and the liquidus +10.
The method for producing a solid-liquid coexisting state metal material according to any one of claims 1 to 6, wherein the temperature is lower than 0 ° C. 8. The solid-liquid coexistence that the state of the metal material comprising a secondary molding for secondary molding step is <br/> claims 1 was characterized by 7, wherein any one of the solid-liquid coexisting state metal material Production method. 9. The method for producing a solid-liquid coexisting state metal material according to claim 8 , wherein the secondary forming step is any one of die casting, molten metal forging, forging and pressing. 10. A billet-shaped claim 8 or 9, wherein the provided with the reheating step of reheating the metal material to solid-liquid coexistence state for the secondary molding of the solid-liquid coexisting state metal material Production method. 11. The solid phase ratio of the molten metal in the cooling step is 0.
The method for producing a solid-liquid coexisting state metal material according to any one of claims 1 to 10, wherein cooling is performed until it becomes 1 or more and 0.7 or less. 12. The molten metal is cooled at 0.2 ° C./s in the cooling step.
The process according to claim 1 to 11 solid-liquid coexisting state metal material according to any one, characterized in that cooling with ec above 5 ° C. / sec or less speed. 13. The molten metal is melted at 0.2 ° C./s in the cooling step.
The method for producing a solid-liquid coexisting state metal material according to any one of claims 1 to 11 , wherein cooling is performed at a rate of ec or more and 2 ° C / sec or less. 14. The molten metal of aluminum, aluminum alloys, magnesium, magnesium alloys, zinc, zinc alloy, copper, copper alloy, 13 any claims 1, characterized in that either the iron and iron alloys A method for producing a solid-liquid coexisting state metal material as described above.