JPH10158756A - Method for molding semi-molten metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for molding molten metal by which a molding having fine and spherical thixo structures is obtd. simply and easily at a low cost without using the conventional mechanical stirring method or electromagnetic stirring method. SOLUTION: An aluminum alloy melt M1 or magnesium alloy melt M1 contg. a crystal grain fining agent held at <50 deg.C in the degree of superheating to a liquidus temp. is directly poured into a holding vessel 20 without using a cooling jig. While this melt is cooled down to the molding temp. at which a prescribed liquid phase rate is exhibited, the melt is held for 30 seconds to 30 minutes. In such a case, the alloy in a liquid state below 10 deg.C in the degree of superheating to the liquidus temp. at which the pouring is executed or the alloy M2 in a solid-liquid coexistence state of <5 deg.C in the fall of the temp. from the liquidus temp. is lowered in the temp. within 10 minutes in the temp. range lower by 5 deg.C than the liquidus temp. from the initial temp., by which the fine primary crystals are crystallized into the alloy liquid. The alloy liquid is then taken out of the holding vessel and is supplied to metal molds 100 for molding, by which the liquid is press molded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a semi-molten metal, and relates to a method for forming a molten aluminum alloy and a molten magnesium alloy containing a crystal grain refiner having a superheat degree of less than 50 ° C. with respect to a liquidus temperature. In the process of pouring directly into a holding container without using a cooling jig, and holding for 30 seconds to 30 minutes while cooling to a molding temperature showing a predetermined liquidus rate, the degree of superheat with respect to the liquidus temperature of the poured liquidus Temperature within 5 minutes from the initial temperature of an alloy in a liquid state of less than 10 ° C. or an alloy in a solid-liquid coexistence state of less than 5 ° C. which is lower than the liquidus temperature by less than 5 ° C. within 10 minutes A semi-molten metal forming method characterized by crystallizing a fine primary crystal in the alloy liquid by lowering the alloy, supplying the alloy from the holding container to the metal mold for removing the alloy, and performing pressure molding. Things.

[0002]

2. Description of the Related Art Thixocasting has attracted attention recently because it has fewer casting defects and segregation than conventional casting methods, has a uniform metal structure, has a long mold life, and has a short molding cycle. Technology. This molding method (A)
The billet used in (1) is characterized by a spheroidized structure obtained by performing mechanical stirring or electromagnetic stirring in a semi-melting temperature range or utilizing recrystallization after processing. On the other hand, a method of semi-solid molding using a material obtained by a conventional casting method is also known.

[0003] This is achieved, for example, by a method (B) of adding Zr or a method (C) of using a carbon-based refining agent in order to produce finer crystals in a magnetic alloy which is likely to generate an equiaxed crystal structure. Al-5% Ti-1% B master alloy is used as a refiner in aluminum alloys.
This is a method (D) in which the raw material obtained by these methods is heated to a semi-melting temperature range to form a primary crystal into a spheroid to form it.

[0004] In addition, after the alloy within the solid solubility limit is heated relatively quickly to a temperature near the solidus, the temperature of the alloy exceeds the solidus in order to equalize the temperature of the entire material and prevent local melting. (E) is a method in which the material is gently heated to an appropriate temperature at which the material becomes soft and molded. Further, a method (F) is known in which a molten aluminum at about 700 ° C. is flowed through an inclined cooling plate to obtain semi-solid aluminum, which is collected in a container and cooled.

On the other hand, unlike a method in which a billet is heated to a semi-melting temperature range and formed, a melt containing a spherical primary crystal is continuously produced and formed without being solidified as a billet. The casting method (G) is known. Further, a method (H) of obtaining a slurry for rheocasting by maintaining a metal, at least a part of which is in a solid-liquid coexistence state, in a semi-molten temperature range by bringing a molten metal into contact with a cooling body and an inclined cooling body is provided. Are known.

[0006]

However, the method (A) described above is complicated in both cases of the stirring method and the method utilizing recrystallization, and has a drawback that the production cost is increased. Further, in the case of magnesium alloy (B), Zr is high, which is a problem in terms of cost. In the method (C), a carbide-based refining agent is used to sufficiently exhibit the refining effect. It is necessary to control Be, which is an antioxidant element, to a low level of, for example, about 7 ppm, which is liable to be oxidized and burned during a heat treatment immediately before molding, which is inconvenient in operation.

On the other hand, in the case of an aluminum alloy, the mere addition of a refining agent results in a thickness of about 500 μm.
It is not easy to obtain a structure of fine crystal grains of 00 μm or less. For this reason, there is a method (D) of adding a large amount of a fine agent, but the fine agent easily sediments at the furnace bottom and is industrially difficult and costly. Further, in the method (E), a thixo-molding method characterized by uniform heating and spheroidization of the material by gently heating beyond the solidus line has been proposed. However, it does not change into the thixo structure (the primary dendrite is spheroidized). According to the method (F), semi-molten aluminum having a structure of spherical particles can be easily obtained, but conditions for molding as it is are not yet established. And (A)
In any of the cases (A) to (F), in order to perform semi-solid molding by the thixo molding method, it is necessary to solidify the liquid phase and raise the temperature of the billet to the semi-molten temperature range again, which is lower than the conventional casting method. The cost is high, the billet as a raw material is difficult to recycle, and the liquid phase ratio cannot be increased due to problems in handling the billet. In the method (G), since the melt containing the spherical primary crystal is continuously generated and supplied, it is more advantageous in terms of cost and energy than thixocast. The interlocking of equipment between a machine for producing raw materials and a casting machine for producing final products is complicated. Specifically, when the casting machine fails, the treatment of the semi-molten metal is troublesome.

Further, the method (H) has the following problems. When the inclined cooling body is used, the metal containing crystal nuclei generated on the inclined cooling body is successively flowed by the metal flowing later, so that the slurry containing fine crystals is maintained by maintaining the metal in the semi-molten temperature range. However, the metal adheres to the cooling body, or the metal remains at the end on the inclined cooling body even if it does not adhere, and therefore, the temperature of the metal when passing through the cooling body cannot be lowered ( As the temperature at the time of passing through the cooling body becomes lower than the liquidus temperature, the finer crystalline metal is obtained, so that the temperature at the time of passing through the cooling body should be lowered).

There are also the following problems. That is, it is supposed to be kept in the latter half melting temperature range for a predetermined time in contact with the cooling body, but unlike the thixocast method, which is once solidified to form a billet and then reheated and then molded. When the semi-molten metal is held as it is after holding for a period of time, it is necessary to obtain an alloy having a suitable liquid phase ratio and a good temperature distribution in a short time in consideration of industrial continuous operation. However, it is not possible to obtain a semi-molten metal for rheocasting having a liquid phase ratio and a temperature distribution suitable for molding simply by holding.

The present invention focuses on the problems of the above-mentioned conventional methods, and can easily and easily form a uniform structure including a spherical primary crystal without using a billet and without using a complicated method. It is an object of the present invention to provide a method for obtaining a semi-solid metal having such a composition and performing pressure molding.

[0011]

In order to solve such a problem, according to the present invention, in the first invention, a grain refining agent having a degree of superheat to a liquidus temperature of less than 50 ° C. A process of pouring a molten aluminum alloy or a molten magnesium alloy directly into a holding container without using a cooling jig, and holding for 30 seconds to 30 minutes while cooling to a molding temperature showing a predetermined liquidus ratio , The alloy in a liquid state having a superheat degree of less than 10 ° C. with respect to the poured liquidus temperature, or a temperature decrease of 5 ° C. with respect to the liquidus temperature
By lowering the temperature within 5 minutes from the initial temperature of the alloy in the solid-liquid coexistence state, which is 5 ° C lower than the liquidus temperature, within 10 minutes, fine primary crystals are crystallized in the alloy liquid, It was taken out of the holding container and supplied to a molding die to perform pressure molding.

Further, in the second invention, the aluminum alloy in the first invention is an aluminum alloy containing 0.03% to 0.30% of Ti, and the superheat degree of the aluminum alloy during pouring into a holding vessel is given. Was less than 30 ° C. Also,
In the third invention, 0.005% to 0.30% of Ti and 0.001% of B are added to the aluminum alloy of the first invention.
An aluminum alloy containing 0.01% or less was added, and the degree of superheat of the alloy when poured into a holding vessel was set to less than 50 ° C.
Further, in the fourth invention, the aluminum alloy contains 0.03% to 0.30% of Ti, 3.0% to 8.0% of Zn,
An aluminum alloy containing 1.0% to 4.0% of Mg was added, and the degree of superheat of the aluminum alloy when poured into the holding container was set to less than 30 ° C.

In the fifth invention, the aluminum alloy contains 0.03% to 0.30% of Ti, and 0.001% to 0.00% of B.
0.01%, Zn: 3.0% to 8.0%, Mg: 1.0%
% To 4.0%, and the degree of superheating of the aluminum alloy when poured into the holding container was set to less than 50 ° C. In the sixth invention, the magnesium alloy is C
a magnesium alloy containing 0.05% to 0.30% of a or a magnesium alloy containing 0.01% to 1.5% of Si and 0.005% to 0.1% of Sr The superheat degree of the magnesium alloy during pouring was set to less than 25 ° C.

In the seventh invention, Al-T
The method of containing B in the molten metal in the hot water supply ladles using the i-B master alloy and the adjustment of the degree of superheat of the molten metal in the hot water supply ladles before pouring into the holding container are performed at 650 ° C.
After melting the mother alloy in the melting and holding furnace held as described above, the temperature is lowered to a predetermined degree of superheat, or the initial temperature of the molten metal in the hot water supply ladle is set to 650 ° C. or more, and the master alloy is melted in the molten metal. A cooling rod is immersed for a predetermined time in order to bring the temperature of the alloy to a predetermined degree of superheat with respect to the liquidus temperature, or a previously prepared alloy melt of the same composition having a high B content and a hot water supply ladle. Mixing or diluting with a molten metal whose temperature has been adjusted to a predetermined degree of superheat, or rapidly melting a predetermined amount of the master alloy in an induction coil of a high-frequency induction heating device and a predetermined amount in a ladle for hot water supply It was decided to put in the molten metal whose temperature was already adjusted to the degree of superheat.

In an eighth aspect based on the seventh aspect, the hot water supply ladle has a thermal conductivity of 1 kcal / mhr ° C.
It is made of the above-mentioned materials, and the average thickness of the hot water supply ladle is 3 mm or less. After the molten metal is drawn into the hot water supply ladle, the temperature of the hot water supply ladle is maintained until pouring into the holding container is completed. A drop prevention protective cover was installed, and after pouring was completed, the protective cover was removed. In the ninth invention, the method of cooling the alloy poured into the holding container is such that at least either air or water is injected from outside the holding container toward the holding container. In addition, the tenth
According to the invention, the temperature of the alloy poured into the holding vessel is maintained by:
By the induction heating, the temperature of each part of the alloy in the holding container is adjusted so as to fall within a target forming temperature range showing a predetermined liquid phase ratio at the latest by the time of forming. Further, in the eleventh invention, at least one of the upper and lower portions of the holding container is kept warm, or is heated to a higher temperature than the central portion of the holding container, or the thickness of the upper and lower portions of the holding container is increased. Was made thinner than the center of the holding container.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The degree of superheating with respect to the liquidus temperature is 50 ° C.
The molten aluminum alloy containing Ti or Ti, B, or the magnesium alloy containing Ca, or the magnesium alloy containing Si, Sr held directly below is poured directly into the holding container without using a cooling jig, and a predetermined liquid In the step of holding for 30 seconds to 30 minutes while cooling to a molding temperature showing a phase ratio, cooling to a molding temperature showing a liquid state alloy or a liquidus ratio having a superheat degree of less than 10 ° C. with respect to a poured liquidus temperature. In the step of holding for 30 seconds to 30 minutes while heating, the alloy in a liquid state having a superheat degree of less than 10 ° C. with respect to the poured liquidus temperature or a temperature decrease of 5 ° C. with respect to the liquidus temperature
By lowering the temperature within 5 minutes from the initial temperature of the alloy in the solid-liquid coexistence state to a temperature lower by 5 ° C. than the liquidus temperature within 5 minutes, fine primary crystals are crystallized in the alloy liquid, and the holding is performed. The temperature of each part of the alloy placed in the container is adjusted by induction heating and local heating or local heat retention of the container so as to fall within a target forming temperature range showing a predetermined liquidus ratio at the latest by the time of forming, Since the alloy is taken out of the holding container and supplied to the mold for forming and molding under pressure, an excellent compact having a fine and uniform structure can be obtained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 16 relate to an embodiment of the present invention. FIG. 1 is a process explanatory view showing a method for forming a semi-molten metal of a hypoeutectic aluminum alloy having a composition higher than the maximum solid solubility limit, and FIG. FIG. 3 is a process explanatory view showing a method for forming a semi-molten metal of a magnesium alloy or an aluminum alloy having an internal composition, FIG. 3 is a process explanatory diagram from the generation of a spherical primary crystal to forming, and FIG. 4 is a metal structure of each process shown in FIG. 5, FIG. 5 is an equilibrium diagram of a typical aluminum alloy, Al-Si alloy, FIG. 6 is an equilibrium diagram of a typical magnesium alloy, Mg-Al alloy, and FIG. FIG. 8 is a process explanatory view showing a method of adding aluminum to the molten metal, and FIG. 8 is an AC4CH alloy (Al-7% Si
FIG. 9 is a graph showing the effect of the amount of B and the degree of superheat of the molten metal on the morphology of the primary crystal of −0.3% Mg−0.15% Ti), and FIG. 9 shows the 7075 alloy (Al-5.5% Zn). -2.5% Mg
A graph showing the effect of the amount of B and the degree of superheat of the molten metal during pouring on the morphology of primary crystals of -1.6% Cu-0.15% Ti).
FIG. 10 is a graph showing the influence of the amount of Zn and the amount of Mg on the morphology of the primary crystal of the Al-Zn-Mg-0.05% Ti alloy, and FIGS. 11 to 13 show the metal structures of the molded articles of the present invention. FIGS. 14 to 16 are microphotographs showing the metal structures of the molded articles of the comparative examples.

In the present invention, as shown in FIGS. 1, 2 and 3, first, a grain refining agent (hereinafter referred to as a refining agent) in which the degree of superheating with respect to the liquidus temperature is kept below 50 ° C.
Is poured into the holding vessel 20 and a hypoeutectic aluminum alloy having a composition equal to or greater than the maximum solid solubility limit or a magnesium alloy or aluminum alloy having a composition within the maximum solid solution limit is formed. In the step of holding for 30 seconds to 30 minutes while cooling to a temperature, an alloy in a liquid state having a superheat degree of less than 10 ° C. with respect to the poured liquidus temperature, or a decrease in temperature with respect to the liquidus temperature of less than 5 ° C. From the initial temperature of the alloy in the solid-liquid coexistence state to the liquidus temperature of 5 ° C
By lowering the temperature of the low temperature section within 10 minutes, fine primary crystals are crystallized in the alloy solution, and the holding vessel 2
From 0, the alloy was supplied to the mold 100 for taking out and forming the alloy to perform pressure molding.

The term "holding vessel" as used in the present invention is used for cooling a poured molten metal to a predetermined liquidus rate to crystallize a fine structure. When the conductivity (room temperature) is less than 1.0 kcal / hr ° C,
Because of good heat insulating properties, the time during which the molten metal poured into the holding container is cooled and held to a temperature indicating a predetermined liquidus rate becomes longer,
The working efficiency is poor, and the generated primary crystals are also coarse and the formability is reduced. Therefore, the thermal conductivity of the holding container 20 is 1.
It is desirable to set it to 0 kcal / mhr ° C. Further, the material may be any of metal, non-metal, and metal coated with non-metal. In addition, the thickness of the holding container 20 is such that after the molten metal is poured, a solidified layer is not generated from the molten metal in contact with the wall surface of the holding container 20 or even if it is generated, it is easily remelted by a high-frequency induction device thereafter. It is desirable to appropriately determine the type according to the type of alloy and the weight of the alloy in the holding container 20. By the way, in producing a casting of about 2 kg, for example, the average thickness is 3
A stainless steel container or a cast iron container having a diameter of not more than mm is used.

The "predetermined liquid phase ratio" means a liquid phase ratio suitable for pressure molding. In high pressure casting such as die casting and squeeze casting, the liquid phase ratio is less than 75%, preferably 40% to 65%. If it is less than 40%, it is not easy to take it out of the holding container 30, and the formability of the taken out material is inferior. On the other hand, if it exceeds 75%, the material is soft and difficult to handle, and the injection sleeve 7 for injecting the molten metal in the die of the die casting machine.
At the time of insertion into 0, 80, there is a problem that the surrounding air is entrained, or the metal structure of the molded casting is segregated to make it difficult to obtain a uniform structure. For this reason, it is 75% or less, preferably 65% or less. In an extrusion method or a forging method, the content is 1.0% to 70%, preferably 10% to 65%. If it exceeds 70%, the tissue may be uneven. For this reason, it is 70% or less, preferably 65% or less. In addition, since the deformation resistance is high at less than 1.0%,
1.0% or more. When an extrusion method or a forging method is performed using an alloy having a liquid phase ratio of less than 40%, the alloy is taken out of the container at a liquid phase ratio of 40% or more, and then the liquid phase ratio is reduced to less than 40%.

The method of pouring the alloy into the holding vessel 20 is capable of generating crystal nuclei (fine crystals) in the poured molten metal, and serves as foreign nuclei or free of crystals. In order to express the effect of the finer agent acting as an accelerating element, the molten metal is poured at a predetermined speed, and the superheat to the liquidus temperature is set to a predetermined superheat of less than 50 ° C.
The degree of superheating varies depending on the type and amount of the fine agent to be added (the reason for the limitation will be described later).

If the pouring speed is too high, air is liable to be entrained in the molten metal to be poured. It is important to pour at the right speed in the range. The appropriate speed is higher than the speed obtained by the formula and lower than the speed obtained by the formula. Formula; Y = 0.015X + 0.02 (preferably Y =
0.03X + 0.02) Formula; Y = 0.17X + 0.6 Here, Y is a pouring speed (° C./s), and X is a pouring weight (k).
g). Specifically, work is performed according to the following procedure. In step [1] of FIGS. 3 and 4, the alloy M ₁ , which is a complete liquid containing a refining agent, placed in a hot water supply ladder (hereinafter also referred to as a “ladle”) 10 is placed in a holding vessel (ceramic coating) in step [2]. (Metal container or ceramic container) 20 is gently and quickly poured into a liquid state alloy containing crystal nuclei (fine crystals) in a liquid state near the liquidus temperature, and an alloy in a solid-liquid coexistence state near the liquidus temperature. obtain.

Next, in step [3], the alloy is placed in a liquid state having a superheat degree of less than 10 ° C. with respect to the poured liquidus temperature or a solid state having a temperature decrease of less than 5 ° C. with respect to the liquidus temperature. 5 ° C from initial temperature in liquid coexistence state to liquidus temperature
Induction heating (by energizing the heating coil 50 around the holding vessel 20) while lowering the temperature of the low temperature section within 10 minutes to crystallize fine primary crystals in the alloy liquid.
Thereby, the temperature of each part of the alloy in the holding container 20 is adjusted so as to fall within a target forming temperature range showing a predetermined liquidus ratio at the latest by the time of forming. In cooling, air 30 (or water 40) is injected from the outside of the holding container 20 toward the holding container 20. If necessary, the upper and lower portions of the holding container 20 are kept in a semi-molten state in the holding container 20 heated by a ceramic 60 or a heater (for example, an infrared heater). A spherical (non-dendritic) primary crystal is formed. The semi-solid alloy M2 having a predetermined liquid phase ratio obtained in this manner is inverted, for example, as in the step [3] -c, and the vertical injection sleeve 70 and the horizontal injection sleeve of die casting are inverted. After being inserted into the mold 80, a molded product is obtained by pressure molding in the mold cavity 100a of the die casting machine. The inverted semi-molten alloy has its upper surface located in the holding container 20 on the chip 90 side. Thus, it is possible to prevent contamination of the oxide present on the surface portion of the semi-molten alloy M _2.

The difference between the method of the present invention shown in FIGS. 1 to 4 and the conventional thixocast method and rheocast method is apparent from the figures. That is, in the present invention, unlike the conventional method, the primary crystals crystallized in the semi-melting temperature range are not forcibly crushed and spheroidized by mechanical stirring or electromagnetic stirring. Crystallized starting from the crystal nucleus introduced inside,
Many of the growing primary crystals are continuously granulated by the heat of the alloy itself (they can be heated and held from the outside if necessary). This is an extremely simple method because the step of semi-solidification by reheating is omitted.

The conditions set in each of the above-mentioned steps, that is, the steps of pouring the molten metal into the holding container 20 and the granulating step shown in FIG. 3 and the reasons for limiting the numerical values shown in the present invention will be described below. In the case of an aluminum alloy containing Ti, the degree of superheating with respect to the liquidus temperature of the alloy is less than 30 ° C., and in the case of an aluminum alloy containing Ti and B, the degree of superheating with respect to the liquidus temperature of the alloy is less than 50 ° C. And C
In the case of an alloy containing a or Si or Sr, the degree of superheat of the alloy with respect to the liquidus temperature is set to less than 25 ° C. Holding container 20
If the degree of superheating of the alloy poured into the alloy to the liquidus temperature is higher than these, (1) the nucleation of crystals is small, and
(2) Since the temperature of the alloy when poured into the container is high, the ratio of remaining crystal nuclei is small, the size of primary crystals is large, and amorphous dendrites are generated.

In the case of aluminum alloy, if the addition of Ti alone is less than 0.03%, the refining effect is small. If it exceeds, coarse Ti compounds are generated and ductility decreases, so that Ti is set to 0.03% to 0.30%.

In the case of adding Ti and B, the content of Ti is 0.005.
%, The effect is small, and if it exceeds 0.30%, a coarse Ti compound is generated and ductility is reduced.
Is set to 0.005% to 0.30%. B promotes miniaturization in combination with Ti, but if it is less than 0.001%, the effect of miniaturization is small, and if it exceeds 0.01%, no further effect can be expected. 001% to 0.
01%.

In a magnesium alloy, when Ca is added, if it is less than 0.05%, the refining effect is small, and 0.3% or less.
Even if added in excess of 0%, no further effect can be expected, so Ca is set to 0.05% to 0.30%. Sr, Si
In the case of composite addition, if Sr is less than 0.005%, the effect of miniaturization is small, and even if added over 0.1%, no further effect can be expected, so that 0.005% to 0.1%. I do. Si promotes miniaturization in combination with Sr, but 0.0
If it is less than 1%, the refining effect is small, and if it exceeds 1.5%, no further effect can be expected, and the ductility is reduced, so that Si is 0.01% to 1.5%. I do.

Al—Z with Ti or Ti or B added
In an n-Mg alloy, if Zn is less than 3%, fine spherical crystals cannot be obtained, and if more than 8% is added, no further effect can be expected, and castability is reduced. Zn is 3% to 8%. If Mg is less than 1%, fine spherical crystals cannot be obtained, and if more than 4% is added, no further effect can be expected, and castability is reduced, so that Mg is 1% to 4%. I do.

The "cooling method" of the alloy poured into the holding container 20 to the molding temperature is performed to forcibly cool the alloy within a predetermined time. Inject air or water from outside.

The "temperature keeping" of the alloy poured into the holding container 20 is performed by changing the temperature of each part of the holding container caused by the rapid cooling to a predetermined level by the induction heating at the latest. The purpose is to adjust the temperature so as to fall within the target forming temperature range indicating the phase ratio, or to maintain the temperature of the semi-molten metal when a failure occurs in the casting machine. If the molding temperature is higher than the eutectic temperature,
By a stage where the representative temperature in 0 (the center temperature of the alloy put in the holding container) does not decrease by more than 10 ° C. with respect to the target molding temperature, a predetermined amount of current is passed within a predetermined time to reach the target molding temperature. On the other hand, the temperature is kept within a temperature range of -5 ° C to + 5 ° C. When the molding temperature is a binary eutectic temperature, a predetermined amount of current is applied within a predetermined time at a stage where the molding temperature is not lower than the eutectic temperature so that a predetermined liquidus ratio is exhibited.

When the alloy poured into the holding container 20 is cooled to show a liquid phase ratio suitable for molding, the upper and lower holding containers need to be "heated or kept warm". If this is not done, coarse dendrite-like primary crystals are generated on the surface of the alloy at the upper part of the holding container and / or the lower part of the holding container, or a solidified layer grows and the holding container 20
Since the temperature distribution of the metal inside becomes non-uniform, when the alloy is inverted and taken out from the holding container 20 even when heated by high-frequency induction, the alloy having a predetermined liquid phase ratio cannot be discharged from the holding container 20, A solidified layer remains inside the holding container 20, making continuous molding difficult or the temperature distribution not being completely improved. For this reason, if the holding time to the molding temperature after pouring is short, in the cooling process, the upper part of the holding container and / or the lower part of the holding container are heated from the center part of the holding container,
Alternatively, the upper part and the lower part of the holding container 20 are preliminarily heated before pouring as well as in the cooling process after pouring as necessary. Reducing the thickness of the upper and lower portions of the holding container 20 is more effective in suppressing the formation of a solidified layer than the central portion of the holding container.

If the degree of superheating relative to the temperature of the liquidus line poured into the holding vessel 20 is higher than 10 ° C., fine spherical crystals cannot be obtained regardless of the cooling rate. For this reason, the degree of superheating of the temperature immediately after pouring to the liquidus temperature is set to less than 10 ° C.
Further, from the initial temperature of the liquid state alloy whose superheat degree to the liquidus temperature is less than 10 ° C., or the alloy in the solid-liquid coexistence state whose temperature decrease to the liquidus temperature is less than 5 ° C. However, if the temperature is lowered by more than 10 minutes in a temperature zone 5 ° C. lower, a fine spherical structure cannot be obtained.
For this reason, the initial temperature of the alloy is 5 ° C. lower than the liquidus temperature.
By lowering the temperature within a low temperature section within 10 minutes, preferably within 5 minutes, fine primary crystals are crystallized in the alloy solution, the alloy is taken out of the holding container 20, and the molding die 1
And then press-formed.

FIG. 7 is a process explanatory view showing a method of adding a finer to a molten metal. It is easy to maintain the temperature of the molten metal in the melting and holding furnace 200 and the ladle 10 at 650 ° C. or higher in advance in order to use the Al—Ti—B mother alloy to contain B in the molten metal in the hot water supply ladle. -It is for melting the Ti-B master alloy. The four methods described in FIG. 7 will be described. In the method (a), the master alloy is melted in a melting and holding furnace 200 previously held at 650 ° C. or higher, and then cooled to a predetermined degree of superheat. In the method (b), the initial temperature of the molten metal in the ladle 10 is set to 650.
℃ or more, after melting the master alloy in the molten metal,
The cooling jig 400 is immersed for a predetermined time in order to bring the molten metal temperature of the alloy to a predetermined degree of superheat with respect to the liquidus temperature (a solidification layer is formed unless the cooling jig 400 is appropriately shaken. If the degree of superheat is 10 degrees or more with respect to the phase line temperature, the effect of crystal refinement due to vibration cannot be expected.) In the method (c), a molten metal having a high content of Ti and B is prepared in advance and mixed and diluted with the molten metal whose temperature in the ladle 10 has been adjusted. In the method (d), the master alloy rapidly melted by the induction furnace is added to the molten metal whose temperature adjustment in the ladle has been completed. In addition, Ca or Si,
In the case of adding Sr, it can be performed in the manner shown in FIG.

The heat conductivity of the hot water supply ladle 10 is 1 kcal.
/ Mhr ° C. or higher, and the thickness of the ladle 10 is set to 3 mm or less to prevent the temperature of the molten metal in the ladle 10 from dropping when hot water is supplied to the ladle 10 and to cool the ladle 10 rapidly after pouring is completed. This is to reduce the amount of adhering metal. The procedure for using the protective cover 10a used to prevent the temperature of the hot water supply ladle 10 from decreasing is shown in FIG.
This is as shown in FIG. The material of the protective cover 10a has, for example, a thermal conductivity of less than 1 kcal / mhr ° C.

FIG. 8 shows an AC4CH alloy (Al-7% Si
It shows the effect of the amount of B and the degree of superheat of the molten metal during pouring on the morphology of the primary crystal of -0.3% Mg-0.15% Ti). T
Unlike the case of adding i and B composites, adding Ti alone results in 3
At temperatures above 0 ° C. no spherical crystals are obtained.

FIG. 9 shows a graph of the 7075 alloy (Al-5.5% Z).
n-2.5% Mg-1.6% Cu-0.15% Ti-based)
4 is a graph showing the effect of the amount of B and the degree of superheat of the molten metal during pouring on the morphology of the primary crystals of. 70 compared to AC4CH alloy
In the case of 75 alloy, fine spherical crystals can be obtained with a high degree of superheat even when only Ti is used without B.

FIG. 10 shows a graph of Al-Zn-Mg-0.05%.
4 is a graph showing the influence of the amounts of Zn and Mg on the morphology of primary crystals of a Ti alloy. By including a predetermined amount of Zn and Mg, fine spherical crystals can be obtained.

[0039]

[Table 1]

Table 1 shows the production conditions of the semi-molten metal and the results of observation of the structure of the compact. The molding was performed by inserting a semi-molten metal into the injection sleeve 70 and then using a squeeze casting machine as shown in FIG. The molding conditions were 9
50 kgf / cm ² , injection speed 0.5 m / s, casting weight (including biscuit) 1.5 kg, and mold temperature 230 ° C.

In Comparative Examples 13 and 14, since the degree of superheating with respect to the liquidus temperature was too high, fine spherical crystals could not be obtained, and only coarse primary crystals as shown in FIG. 11 could be obtained. In Comparative Example 15, since the passage time in the temperature section 5 ° C. lower than the liquidus temperature from the initial temperature of the molten metal poured into the holding container 20 was longer than 10 minutes, the holding time in Comparative Example 16 was Due to the length, only coarse primary crystals can be obtained.

In Comparative Examples 17 and 18, since the upper and lower portions of the holding container were not kept warm or heated, the temperature distribution of the alloy in the holding container 20 was uneven even when induction heating was performed. It is. Comparative Example 19, Comparative Example 20
In this case, only a coarse primary crystal can be obtained because no refiner is contained. This state is shown in FIG.

In Comparative Example 21, only Sr was added, and the alloy was not much finer than the alloy without Sr. This state is shown in FIG. In Comparative Example 22,
No coarsening agent is added, and only coarse primary crystals can be obtained because of a high degree of superheat relative to the liquidus temperature. In Comparative Example 23, a fine spherical primary crystal having a low Zn content was not obtained.

On the other hand, in the present invention 1 to the present invention 12, FIG.
1, fine spherical primary crystals cannot be obtained as shown in FIGS.

[0045]

As is apparent from the above description,
In the method for forming a semi-molten metal according to the present invention, a compact having a fine and granular structure can be obtained simply and easily at low cost without using the conventional mechanical stirring method or electromagnetic stirring method.

[Brief description of the drawings]

FIG. 1 is a process explanatory diagram showing a method for forming a semi-molten metal of a hypoeutectic aluminum alloy having a composition not less than the maximum solid solubility limit according to the present invention.

FIG. 2 is a process explanatory diagram showing a method for forming a semi-solid gold of a magnesium alloy or an aluminum alloy having a composition within the maximum solid solubility limit according to the present invention.

FIG. 3 is an explanatory diagram of steps from generation of a spherical primary crystal to molding according to the present invention.

FIG. 4 is a schematic diagram of a metal structure in each step shown in FIG.

FIG. 5 shows a typical aluminum alloy according to the present invention, Al-
FIG. 3 is an equilibrium diagram of a Si-based alloy.

FIG. 6 is an equilibrium diagram of a Mg—Al alloy, which is a typical magnesium alloy according to the present invention.

FIG. 7 is a process explanatory view showing a method for adding the finely-divided agent to the melt according to the present invention.

FIG. 8 shows an AC4CH alloy (Al-7% Si) according to the present invention.
It is a graph which shows the influence of the amount of B and the superheat degree of the molten metal at the time of pouring on the form of the primary crystal of -0.3% Mg-0.15% Ti).

FIG. 9 shows a 7075 alloy (Al-5.5% Z) according to the present invention.
n-2.5% Mg-1.6% Cu-0.15% Ti-based)
4 is a graph showing the effect of the amount of B and the degree of superheat of the molten metal during pouring on the morphology of the primary crystals of.

FIG. 10: Al-Zn-Mg-0.05% according to the present invention
4 is a graph showing the influence of the amounts of Zn and Mg on the morphology of primary crystals of a Ti alloy.

FIG. 11 shows a molded article of the present invention (AC4CH-0.15%
It is a mimic photo of a micrograph showing the metal structure of Ti).

FIG. 12 shows a molded article of the present invention (AZ91-0.01% S
It is a mimetic diagram of a micrograph showing a metal structure of (r-0.4% Si).

FIG. 13 shows a molded article of the present invention (7075-0.15% T).
It is a mimicking figure of a micrograph showing the metal structure of i-0.002% B).

FIG. 14 shows a molded product of a comparative example (AC4CH-0.15% T).
It is a mimetic diagram of a micrograph showing metal structure of i).

FIG. 15 is a microphotograph showing the metallographic structure of a molded article (AZ91) of a comparative example.

FIG. 16 shows a molded product of a comparative example (AZ91-0.01% S
It is a mimetic diagram of a micrograph showing a metal structure of r).

FIG. 17 is a micrograph of a micrograph showing a metal structure of a compact (7075) of a comparative example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Ladle for hot water supply (ladle) 10a Protective cover 20 Holding container (ceramic container or metal container) 30 Air 40 Water 50 Heating coil (coil) 60 Ceramic 70 Vertical injection sleeve 80 Horizontal injection sleeve 90 Tip 100 Mold 100a Metal mold cavity 200 melting and holding furnace 200A melting and holding furnace 300 Al-Ti-B rod 400 cooling jig M ₁ metal melt M ₂ semi-molten metal T retention time t vessel metal temperature

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C22C 21/10 C22C 21/10 23/00 23/00 (72) Inventor Yasunori Harada 1980 No. 1980 off the coast of Kogushi-ji, Oji, Ube City, Yamaguchi Prefecture Ube Industries, Ltd., Machinery & Engineering Business Unit (72) Inventor Hiroto Sasaki 1980, Ogishi, Ogushi, Ube City, Ube City, Yamaguchi Prefecture Ube Industries, Ltd., Machinery & Engineering Business Unit

Claims (11)

[Claims] 1. An aluminum alloy melt or a magnesium alloy melt containing a crystal grain refining agent maintained at a superheat degree of less than 50 ° C. with respect to a liquidus temperature directly into a holding vessel without using a cooling jig. In the step of pouring and holding for 30 seconds to 30 minutes while cooling to a molding temperature showing a predetermined liquidus rate, the superheat degree with respect to the liquidus temperature of the poured liquid state alloy less than 10 ° C., or Fine primary crystals are obtained by lowering the temperature within 5 minutes from the initial temperature of the alloy in a solid-liquid coexistence state whose liquidus temperature is less than 5 ° C to 5 ° C lower than the liquidus temperature within 10 minutes. A semi-molten metal, which is crystallized in the alloy solution, taken out of the holding container, supplied to a molding die and subjected to pressure molding. 2. An aluminum alloy containing 0.03% of Ti
The method for forming a semi-molten metal according to claim 1, wherein the aluminum alloy is 0.30% added, and the degree of superheat of the aluminum alloy is less than 30 ° C when poured into a holding container. 3. An aluminum alloy containing 0.005% of Ti
2. The aluminum alloy as claimed in claim 1, wherein said aluminum alloy is added to the holding container at a temperature of less than 50.degree. Method for forming molten metal. 4. An aluminum alloy containing 0.03% or more of Ti.
0.30%, Zn: 3.0% to 8.0%, Mg: 1.0%
2. A method for forming a semi-molten metal according to claim 1, wherein the aluminum alloy is added to the holding vessel at a rate of superheat of less than 30 [deg.] C. when poured into a holding container. 5. An aluminum alloy containing 0.03% or more of Ti.
0.30%, B is 0.001% to 0.01%, Zn is 3.0% to 8.0%, and Mg is 1.0% to 4.0% aluminum alloy. The method for forming a semi-molten metal according to claim 1, wherein the degree of superheat of the aluminum alloy during pouring is less than 50 ° C. 6. A magnesium alloy containing 0.05% of Ca.
A magnesium alloy to which 0.30% is added, or 0.01% to 1.5% of Si and 0.005% to 0.1% of Sr.
The method for forming a semi-molten metal according to claim 1, wherein the magnesium alloy is 1% added, and the superheat degree of the magnesium alloy is less than 25 ° C when poured into a holding container. 7. A method for using an Al-Ti-B master alloy to contain B in the molten metal in the hot water supply ladle and adjusting the degree of superheat of the molten metal in the hot water supply ladle before pouring the molten metal into the holding container. After melting the master alloy in a melting and holding furnace maintained at 650 ° C. or higher, the temperature is lowered to a predetermined degree of superheat, or the initial temperature of the melt in the hot water supply ladder is set to 650 ° C. or higher, and the master alloy is melted in the melt. After that, the cooling rod is immersed for a predetermined time to bring the molten alloy temperature to a predetermined degree of superheat with respect to the liquidus temperature, or a previously prepared molten alloy of the same composition having a high B content is supplied. Mix or dilute the molten metal whose temperature has been adjusted to a predetermined degree of superheat in the ladle for heating, or rapidly melt the mother alloy in a predetermined amount in the induction coil of the high-frequency induction heating device, and Already at a certain degree of superheat The method of forming a semi-molten metal according to claim 3, wherein the molten metal is charged into a molten metal whose temperature has been adjusted. 8. The hot water supply ladle has a thermal conductivity of 1 kcal.
/ Mhr ° C. or higher, and the average thickness of the hot water supply ladles is 3 mm or less. The method for forming a semi-molten metal according to claim 7, wherein a protective cover for preventing temperature decrease is provided on the ladle, and the protective cover is removed after pouring is completed. 9. The method of cooling an alloy poured into a holding container, wherein at least one of air and water is injected from the outside of the holding container toward the holding container. Forming method of semi-solid metal. 10. The temperature of the alloy poured into the holding container is maintained by a target forming temperature range that shows a predetermined liquidus ratio by the time of forming the temperature of each part of the alloy in the holding container by induction heating at the latest. The method for forming a semi-molten metal according to claim 1, wherein the temperature is adjusted so as to be contained in the inside. 11. Heating at least one of the upper and lower parts of the holding container, heating the holding container to a higher temperature than the central part of the holding container, or reducing the thickness of the upper and lower parts of the holding container 2. The method according to claim 1, wherein the thickness is smaller than a central portion of the first member.
The method for forming a semi-solid metal according to the above.