JP3246319B2 - Forming method of semi-molten metal - Google Patents

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 more particularly to an alloy in a liquid state having a crystal nucleus at a liquidus temperature or higher, or an alloy having a crystal nucleus in a solid-liquid coexistence state at a molding temperature or higher. In a heat-insulating container having a heat-insulating effect, while cooling to a molding temperature showing a predetermined liquidus ratio for 5 seconds to 60 seconds, (1) the superheat temperature (initial temperature) of the metal in the heat-insulating container. Temperature) is equal to or higher than the liquidus temperature, the superheat (X ° C.) for the liquidus is less than 10 ° C., and the temperature from the superheat temperature (initial temperature) to the liquidus temperature of the alloy is Y = 10−X (Y minutes) calculated by the relational expression
By lowering the temperature within a shorter time than the superheat temperature (initial temperature) held in the insulated container and lowering the temperature by 5 ° C. below the liquidus temperature within 15 minutes, the fine Crystallize the primary crystal in the alloy liquid,
The present invention relates to a method for forming a semi-molten metal, which comprises supplying the alloy to a molding die and performing pressure molding,
(2) When the initial temperature of the metal in the heat insulating container is equal to or lower than the liquidus temperature, the temperature in a section of 5 ° C lower than the liquidus temperature from the initial temperature is lowered within 15 minutes, so that the fine particles in the liquid are reduced. The present invention relates to a method for forming a semi-molten metal, wherein a primary crystal is crystallized in the alloy liquid, and the alloy is supplied to a molding die and subjected to pressure molding.

[0002]

2. Description of the Related Art The thixocast method has advantages such as less casting defects and segregation, a uniform metal structure, a longer mold life and a shorter molding cycle than conventional casting methods.
This is a technology that has recently attracted attention. The billet used in this molding method (A) is characterized by a spheroidized structure obtained by performing mechanical stirring or electromagnetic stirring in a semi-melting temperature range, or by utilizing recrystallization after processing. It is. On the other hand, a method of semi-solid molding using a material obtained by a conventional casting method is also known. This is, for example, a method of adding Zr (B) or a method of using a carbon-based refining agent (C) in order to generate finer crystals in a magnesium alloy which easily generates an equiaxed crystal structure. Al as a refiner in aluminum alloys
This is a method (D) in which a -5% Ti-1% B mother alloy is added about 2 to 10 times that of the conventional method, and the material obtained by these methods is heated to a semi-melting temperature range to form a primary crystal into a spheroid to form it. How to Also, for alloys within the solid solubility limit, after heating relatively quickly to a temperature near the solidus, the material exceeds the solidus in order to equalize the temperature of the entire material and prevent local melting. A method (E) of forming by heating gently to an appropriate temperature at which the material is softened is known.

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 (F) is known.

[0004]

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 the magnesium alloy, the method (B) has a high Zr and is problematic in terms of cost, and in the method (C), a carbide-based refining agent is used to sufficiently exhibit its refining effect. In order to achieve this, the antioxidant element Be
Needs to be controlled to, for example, about 7 ppm, which is liable to be oxidized and burned during the heat treatment immediately before molding, which is inconvenient in operation.

On the other hand, in the case of an aluminum alloy, it is about 500 μm by simply adding a refining agent.
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 gradually heating after exceeding the solidus line has been proposed. However, it does not change into the thixo structure (the primary dendrite is spheroidized).

In addition, in any of the thixo-molding methods (A) to (E), in order to perform semi-solid molding, it is necessary to solidify the liquid phase and raise the temperature of the billet to the semi-molten temperature range again. The cost is higher than the law. Also,
In the method (F), since a melt containing a spherical primary crystal is continuously generated and supplied, it is more cost-effective and energy-efficient than thixocast, but a metal raw material comprising a spherical structure and a liquid phase is used. The interlocking of equipment between the machine to manufacture and the casting machine to manufacture the final product is complicated.

The present invention focuses on the problems of the above-mentioned conventional methods, and can easily and easily obtain a semi-molten metal having a fine primary crystal without using a billet and employing a complicated method. It is another object of the present invention to provide a method for pressure molding.

[0008]

In order to solve such a problem, according to the present invention, in the first invention, an aluminum alloy or a magnesium alloy having a superheat degree of less than 100 ° C. with respect to a liquidus temperature is maintained. A liquid state alloy having a crystal nucleus having a superheat degree (X ° C.) of less than 10 ° C. with respect to a liquidus line obtained by pouring the molten metal directly into an insulated container without using a jig or a high-pressure casting method or extrusion. A method of forming by an extrusion method or a forging method, wherein the liquid phase ratio of the alloy is 20 to 90% in the case of a high-pressure casting method, and 0.1% in an extrusion method or a forging method.
In the step of cooling in an insulated container for 5 seconds to 60 minutes to a molding temperature showing a liquidus ratio of 1 to 70%, a relational expression of Y = 10-X is used from the initial temperature to the liquidus temperature of the alloy. The temperature is reduced in a time shorter than the time (Y minutes) calculated in
In addition, in the heat-insulating container, a fine primary crystal is crystallized in the alloy liquid by lowering the temperature within an interval of 5 ° C. from the initial temperature to the liquidus temperature within 15 minutes, thereby forming the alloy. It was supplied to a metal mold for pressure molding. In the second invention, the degree of superheat with respect to the liquidus temperature is 10%.
High-pressure casting of an alloy in the solid-liquid coexisting state above the forming temperature with crystal nuclei obtained by pouring a molten aluminum alloy or magnesium alloy held at less than 0 ° C directly into an insulated container without using a jig A molding method in which the liquid phase ratio of the alloy is 20 to 90% in the case of a high-pressure casting method, and 0 to 90% in the case of an extrusion method or a forging method.
In the step of cooling in an insulated container for 5 seconds to 60 minutes to a molding temperature showing a liquidus ratio of 1 to 70%, a section in the insulated container having a temperature lower by 5 ° C. than the liquidus temperature from the initial temperature. The temperature was lowered within 15 minutes to crystallize fine primary crystals in the alloy liquid, and the alloy was supplied to a molding die and pressure-molded.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An alloy having a crystal nucleus in a liquid state at a liquidus temperature or higher, or an alloy having a crystal nucleus in a solid-liquid coexistence state at a molding temperature or higher is, for example, an aluminum alloy,
In the step of holding the magnesium alloy in a heat insulating container having an insulating effect for 5 seconds to 60 seconds while cooling to a molding temperature showing a predetermined liquid phase ratio, (1) the initial temperature of the metal in the container is changed to the liquid phase Above the linear temperature, the superheat (X ° C.) with respect to the liquidus is less than 10, and the relationship from the superheat temperature (initial temperature) to the liquidus temperature of the alloy is calculated by a relational expression of Y = 10−X. Temperature within a time period shorter than the heating time (Y minutes), and within 15 minutes a section of 5 ° C lower than the liquidus temperature from the superheat temperature (initial temperature) held in the heat insulating container. By lowering the temperature, or (2) when the initial temperature of the metal in the heat-insulating container is lower than the liquidus temperature, a temperature range of 5 ° C. lower than the liquidus temperature from the initial temperature is set within 15 minutes. By dropping, fine and spherical in the liquid And primary crystal to generate the, by pressure molding is supplied to the mold the alloy of this semi-molten state, the molded body of a homogeneous structure is obtained.

[0010]

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 8 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. 2 is a semi-molten metal of a magnesium alloy or an aluminum alloy having a composition within the maximum solid solution limit. FIG. 3 is a schematic view of each step from generation of a spherical primary crystal to molding, FIG. 4 is a schematic view of a metal structure of each step shown in FIG. 3, and FIG. 5 is a typical aluminum alloy. A certain Al-Si alloy equilibrium diagram,
FIG. 6 is an equilibrium state diagram of a Mg—Al-based alloy which is a typical magnesium alloy, FIG. 7 is a micrograph showing a metal structure of a molded article of the present invention, and FIG. 8 is a microscope showing a metal structure of a molded article of a comparative example. A photograph is shown.

In the present invention, as shown in FIG. 1, FIG. 2, FIG. 5, and FIG. 6, (1) First, the superheat degree is maintained at less than 300.degree. A hypoeutectic aluminum alloy of the composition described above or a magnesium alloy of the composition within the maximum solid solubility limit, and a melt of aluminum alloy are brought into contact with the surface of a jig at a temperature lower than the melting point of the alloy to generate crystal nuclei in the liquid. Or (2) pouring a melt of an aluminum alloy or a magnesium alloy having a superheat degree of less than 100 ° C. with respect to a liquidus temperature directly into an insulated container without using a jig to generate crystal nuclei; A liquid-state alloy having crystal nuclei having a superheat degree (X ° C.) of less than 10 ° C. with respect to a liquidus line in an insulated container is cooled to a eutectic temperature showing a predetermined liquidus rate or a forming temperature higher than a solidus temperature. 5 while cooling
In the step of holding for from 60 seconds to 60 minutes, the time up to the liquidus temperature of the alloy is calculated as the time (Y
Min), and the temperature is lowered from the initial temperature held in the insulated container by 5 to the liquidus temperature.
By lowering the temperature of the section having a lower temperature of 15 ° C. within 15 minutes, fine spherical primary crystals are crystallized in the alloy solution, and the alloy is supplied to a molding die and pressure molded.

Further, the alloy in a solid-liquid coexistence state having a molding temperature higher than the eutectic temperature or the solidus temperature in the heat insulating container is cooled to a forming temperature showing a predetermined liquid phase ratio in the heat insulating container. In the step of holding for 5 seconds to 60 minutes while heating, the temperature of a section of 5 ° C. lower than the liquidus temperature from the initial temperature held in the heat-insulating container is lowered within 15 minutes to form a fine spherical shape. A primary crystal is crystallized in the alloy liquid, and the alloy is supplied to a molding die and pressure-molded. The predetermined liquid phase ratio means a ratio of liquid phases suitable for pressure molding. In high-pressure casting such as die casting and squeeze casting, the liquid phase ratio is 20% to 90%, preferably 30% to 90%.
70% (less than 30%, the moldability of the material is inferior; if it is 70% or more, the material is soft, so that not only handling is difficult, but also it is difficult to obtain a uniform structure). % To 70%.

The heat-insulating container referred to in the present invention may be a metal container or a non-metal container, a metal container having a non-metal material containing a semiconductor applied to the surface, or a non-metal material containing a semiconductor. Into a metal container that combines
In addition, the container can be locally or entirely heated or cooled from inside or outside the container, and the thickness of the heat-insulating container varies depending on the location of the container as necessary.

Specifically, the operation proceeds according to the following procedure. In step [1] of FIGS. 3 and 4, the metal M, which is a complete liquid, placed in the ladle 10 is mixed in step [2] with (a) a low-temperature molten metal using a cooling jig 20 (if necessary). A crystal nucleus is generated from a crystal nucleus promoting element) and poured into a ceramic container 30 or a ceramic-coated metal container 30A having a heat insulating effect, or (b) a low-temperature molten metal just above the melting point (necessary). Element which promotes the formation of crystal nuclei can be added, if necessary).
An alloy immediately below or directly above the liquidus line containing a large number of crystal nuclei is obtained by either of the methods described above.

Next, in step [3], the alloy is held in the heat insulating container 30 (or 30A) in a semi-molten state. During this period, ultrafine granular or non-dendritic primary crystals are generated from the introduced crystal nuclei (step [3]-).
a) As the solid phase ratio increases with a decrease in the temperature of the melt, it grows as a spherical primary crystal (step [3] -c). After the metal M having the predetermined solid phase ratio thus obtained is inserted into the die-cast injection sleeve 40 as in (step [3] -d), for example, it is inserted into the mold cavity 50a of the die-casting machine. Press molding to obtain a molded product.

The difference between the embodiment of the present invention shown in FIGS. 1, 2, 3 and 4 and the conventional thixocast method and rheocast method is apparent from the figures. That is, in the present invention, the dendrite-like (isotropic dendrite) primary crystals crystallized in the semi-melting temperature region as in the conventional method are not forcibly crushed and spheroidized by mechanical stirring or electromagnetic stirring. A large number of primary crystals which crystallize and grow with the temperature drop in the semi-melting temperature region starting from the crystal nuclei introduced into the alloy are heated by the heat of the alloy itself (if necessary, it may be heated and held from outside. ) It is an extremely simple method because it is continuously spheroidized, and the step of semi-melting by reheating the billet in the thixocasting method is omitted.

The casting conditions set in each of the above-mentioned steps, ie, the step of pouring the ceramic jig 20 shown in FIG. 3, the formation of primary crystals, the spherical step, and the forming step,
Spheroidizing conditions and molding conditions, the first invention, the second invention,
The reasons for limiting the numerical values shown in the third and fifth inventions will be described below. When the initial temperature of the alloy held in the heat insulating container 30 has a degree of superheat of 10 ° C. or more with respect to the liquidus line, the jig 20 is used to introduce crystal nuclei into the molten metal, and a predetermined liquid phase is used. Even if cooling is performed under any conditions up to the molding temperature showing the rate, only primary crystals having an irregular shape of 300 μm or more are generated, so that fine and spherical primary crystals cannot be obtained. For this reason, the initial temperature of the alloy held in the heat insulating container 30 is set to less than 10 ° C.

When the initial temperature of the alloy held in the heat insulating container 30 has a degree of superheat of less than 10 ° C. with respect to the liquidus, the passing time (minute) to the liquidus temperature is represented by Y, Assuming that (° C.) is X, if the temperature does not drop to the liquidus temperature in a shorter time than the time calculated by the relational expression of Y = 10−X, it is 300 μm or more as in the case where the superheat is 10 ° C. or more. A primary crystal of irregular shape is generated. Therefore, as described above, the temperature is lowered to the liquidus temperature in a shorter time than the time obtained by the relational expression of Y = 10-X. Further, even if the temperature is lowered from the initial temperature to the liquidus temperature in a shorter time than the time obtained by the above relational expression, the section of the temperature lower than the liquidus temperature by 5 ° C. from the initial temperature within 15 minutes. If the temperature does not drop, primary crystals having an irregular shape of 300 μm or more tend to be generated, and the size of spherical primary crystals tends to be 200 μm or more. Therefore, from the initial temperature to the liquidus temperature, 5
The time during which the temperature is lowered in the section where the temperature is lower by 15 ° C. is within 15 minutes.

Further, when the initial temperature of the alloy held in the heat insulating container 30 is in a solid-liquid coexisting state lower than the liquidus temperature,
One section of 5 ° C lower than the liquidus temperature from the initial temperature
If the temperature does not drop within 5 minutes, a primary crystal having an irregular shape of 300 μm or more may be generated, or the size of the spherical primary crystal may be 200 μm.
μm or more. For this reason, the time during which the temperature falls in a section 5 ° C. lower than the liquidus temperature from the initial temperature is set to 15 minutes or less. In addition, the time during which the alloy is cooled to a predetermined molding temperature and held in the heat insulating container 30 is:
If it is less than 5 seconds, it is not easy to reach a temperature at which a desired liquid phase ratio is obtained, and it is also difficult to form a spherical primary crystal. On the other hand, when the retention time exceeds 60 minutes, the size of the generated spherical primary crystals tends to exceed 200 μm,
A primary crystal having an irregular shape of 300 μm or more may be generated, so that semi-solid molding may be difficult, or mechanical properties may be reduced. For this reason, the holding time is set to 5 seconds to 60 minutes.

When the casting temperature is higher than the melting point by 300 ° C. or more, or when the surface temperature of the jig 20 is higher than the melting point, (1) the nucleation of the crystal is small, and (2) the crystal is poured into the container. Since the temperature of the molten metal M is higher than that of the liquidus line, the ratio of the remaining crystal nuclei is small, and the size of the primary crystal increases. For this reason, the casting temperature is set such that the degree of superheat with respect to the liquidus temperature is less than 300 ° C., and the surface temperature of the jig is set lower than the melting point of the alloy. The degree of superheating with respect to the liquidus temperature is 10
By making the temperature of the jig 20 lower than the melting point of the alloy M by 50 ° C. or more by setting the temperature to be less than 0 ° C., more preferably 50 ° C. or less, to obtain a finer primary crystal size. Can be done. However, when the degree of superheating with respect to the liquidus temperature is too low, when the temperature of the jig 20 is too low, when the contact area of the molten metal with the jig 20 is too large, or when the molten alloy having a small heat capacity is When the metal is supplied on the jig 20, there is a problem that the metal adheres to the jig 20 and it becomes difficult to supply the metal to the heat insulating container. In this case, as a method of generating crystal nuclei, combining cooling with the jig 20 and cooling with the insulated container avoids the problem of adhesion of metal to the jig 20 and easily inserts the alloy into the insulated container. Can be. There are two methods for bringing the molten metal M into contact with the jig 20: a method of moving the molten metal M on the surface of the jig 20 (flowing the molten metal to the inclined jig 20) and a method of moving the molten metal M through the molten metal. There is. The jig referred to here is a jig which gives a cooling action to the molten metal when the molten metal flows down. Instead, for example, a cylindrical pipe of a water heater may be used.

The heat insulating container 30 for holding the molten metal that has dropped just below the liquidus line has a heat insulating effect in order to make the generated primary crystals spherical and to obtain a desired liquid phase ratio after a predetermined time. The material is not limited, and it is preferable that the material has heat retention and has poor wettability with the molten metal. As described above, either a metal container or a non-metal container may be used. When a ceramic container having air permeability is used as the heat insulating container 30, the magnesium alloy may be oxidized or oxidized.
It is desirable to set the outside of the container to a predetermined atmosphere (inert atmosphere, reduced-pressure atmosphere, or the like) because it is easy to burn. Also,
Be and Ca are added to the molten metal in advance to prevent oxidation.
Is desirably added. The shape of the heat insulating container 30 is not limited to a cylindrical shape, but may be a shape suitable for a subsequent molding method. Further, it may be directly charged into a ceramic injection sleeve instead of the heat insulating container.

In high-pressure casting, the liquid phase ratio immediately before molding is 2
If it is less than 0%, it is not easy to obtain a molded product having high deformation resistance during molding and good quality. If it exceeds 90%, a molded article having a uniform structure cannot be obtained. For this reason, the liquid phase ratio at the time of molding is set to 20% to 90%. By setting the actual liquid phase ratio to 30% to 70%,
Further, a homogeneous and high-quality molding material can be easily molded under pressure. Further, when forming an Al-Si alloy having a composition close to the eutectic composition, when it is necessary to generate eutectic Si in the heat insulating container and reduce the liquid phase ratio to within 80%, it is a Si improving element. Addition of Na, Sr, or the like is advantageous for miniaturizing eutectic Si and improving ductility. The means for pressure molding is not limited to high pressure casting represented by squeeze casting and die casting.
Various methods of pressure molding such as an extrusion method and a forging method are included.

The material of the jig 20 for contacting the molten metal M is not limited as long as it can lower the temperature of the molten metal, but copper, copper alloy, aluminum, aluminum, and aluminum having particularly high thermal conductivity are used. A jig 20 made of a metal such as an alloy and cooled and controlled so that the temperature can be maintained at a certain temperature or less is preferable because it generates many crystal nuclei. In addition,
When the molten metal contacts the jig 20, the solid metal is
It is effective to apply a nonmetallic material to the metal to prevent the metal from adhering to the metal, or to use a nonmetallic material having a high thermal conductivity. As a method of applying, any of a mechanical, chemical, or physical method may be used.

By bringing the molten metal into contact with the jig 20,
Alternatively, a molten metal having a superheat degree of less than 100 ° C., more preferably less than 50 ° C. with respect to a liquidus line is poured directly into an insulated container without coming into contact with the jig 20 to obtain an alloy directly above or below the liquidus line containing a large number of crystal nuclei. It is possible to get
Further, Ti and B are added to an aluminum alloy to generate a large number of crystal nuclei and obtain a uniform and fine spherical structure, and Sr, Si, and Ca are added to a magnesium alloy.
May be added. If the Ti content is less than 0.005%, the refining effect is small, and if it exceeds 0.30%, coarse Ti compounds are generated and ductility is reduced.
30%. B promotes miniaturization in combination with Ti, but if it is less than 0.001%, the miniaturization effect is small.
No further effect can be expected even if it exceeds 2%, so B is set to 0.001% to 0.02%. If Sr is less than 0.005%, the effect of miniaturization is small,
Even if added in excess of 1%, no further effect can be expected, so Sr is made 0.005 to 0.1%. 0.005
By adding 0.01% to 1.5% of Si in combination with% to 0.1% of Sr, finer crystal grains can be obtained than in the case of adding Sr alone. If the Ca content is less than 0.05%, the refining effect is small, and if the content exceeds 0.30%, no further effect can be expected.
%.

When a fine spherical primary crystal is obtained without using a cooling jig, setting the degree of superheating to the liquidus line to less than 100 ° C., more preferably less than 50 ° C., has an insulating effect. This is because the alloy poured into the heat insulating container 30 is brought into a liquid state having crystal nuclei or a solid-liquid coexisting state at a molding temperature or higher. If the temperature of the molten metal in the poured container 30 is high, the crystal nuclei disappear and fine spherical primary crystals cannot be obtained. bad. In addition, the surface of the poured molten metal is oxidized or burned, which is inconvenient.

FIGS. 9 and 10 show the effect of the holding time on the crystal grain size of typical magnesium alloy AZ91 and aluminum alloy AC4CH, respectively. The retention time is
This is the holding time from pouring into the heat insulating container to the molding temperature. Here, the molding temperature is a typical molding temperature at which the liquid phase ratio is about 50%.
585 ° C for CH. Although there is a difference between the alloys in the retention time dependency of the crystal grain size, in any case, the tendency to exceed 200 μm becomes stronger after 60 minutes, but in the present invention, a fine primary crystal smaller than 200 μm is easily obtained. FIG.
1 and FIG. 12 show the influence of the degree of superheat on the liquidus line and the holding time from the initial temperature in the insulated container to the liquidus temperature on the crystal grain size of AZ91 and AC4CH in the holding container, respectively. In the present invention, (superheat degree [° C.], transit time [min]) below the straight line connecting the coordinates (10, 0) and the coordinates (0, 10) is less than 200 μm in the present invention as shown in FIG. Although a fine primary crystal is generated, a coarse primary crystal of 300 μm or more as shown in FIG. In FIG. 11, a region surrounded by points (0, 6), points (5, 5), and points (6, 0) is shown in FIG. 11 and FIG. In FIG. 12, at the point (0, 7), the point (5, 5), and the area surrounded by the point (5, 0)), a more uniform fine primary crystal is obtained. FIGS. 13 and 14 show AZ91 and AC4CH, respectively.
1 shows the effect of the holding time (from the initial temperature in the heat insulating container to the liquidus temperature −5 ° C.) on the crystal grain size. As the holding time becomes longer, the crystal grain size becomes larger, and when it exceeds 15 minutes, the tendency to exceed 200 μm becomes stronger, and coarse primary crystals having an irregular shape are generated. In the examples of the present invention in which the retention time is less than 15 minutes, the tendency of observing fine primary crystals of less than 200 μm is increased.

[0027]

As is apparent from the above description, in the method for forming a semi-molten metal according to the present invention, an aluminum alloy or magnesium alloy having a crystal nucleus in a liquid state at a liquidus temperature or higher, or a crystal nucleus. An aluminum alloy or a magnesium alloy in a solid-liquid coexisting state having a molding temperature or higher in a heat-insulating container having a heat-insulating effect,
A molding method for molding the alloy by high-pressure casting, extrusion, or forging, wherein the liquid phase ratio of the alloy is 20 to 90% in the case of high-pressure casting, and 0.1% in the case of extrusion or forging.
In the step of cooling for 5 seconds to 60 minutes to a molding temperature showing a liquidus ratio of up to 70%, (1) if the initial temperature of the metal in the container is higher than the liquidus temperature, the degree of superheat to the liquidus (X ° C.) is less than 10 ° C., and the temperature is lowered to the liquidus temperature of the alloy in a time shorter than the time (Y minute) calculated by the relational expression of Y = 10−X, and Within 15 minutes from the initial temperature within 5 minutes below the liquidus temperature, or (2) when the initial temperature of the metal in the vessel is lower than the liquidus temperature, By lowering the temperature within 5 minutes in a section 5 ° C lower than the liquidus temperature within 15 minutes, fine primary crystals are crystallized in the alloy liquid, and a harmful alloy having a predetermined liquidus ratio is formed. Conventional mechanical stirring method and electromagnetic stirring method Yorazu, moldings can be obtained having a fine and spherical tissue in a simple easily and at low cost.

[Brief description of the drawings]

FIG. 1 is a process explanatory view 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 an example of the present invention.

FIG. 2 is a process explanatory view showing a method for forming a semi-molten metal of a magnesium alloy or an aluminum alloy having a composition within a maximum solid solution limit according to an embodiment of the present invention.

FIG. 3 is a schematic view of each step from generation of a spherical primary crystal to molding according to an example of the present invention.

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

FIG. 5 is an equilibrium diagram of an Al—Si alloy which is a typical aluminum alloy according to the present invention.

FIG. 6 is a diagram showing a typical magnet alloy according to the present invention, Mg-
FIG. 3 is an equilibrium diagram of an Al-based alloy.

FIG. 7 is a micrograph showing a metal structure of a molded article according to an example of the present invention.

FIG. 8 is a micrograph showing a metal structure of a molded article of a comparative example.

FIG. 9 is a graph showing the effect of holding time on the crystal grain size of a conventional alloy (AZ91).

FIG. 10 is a graph showing the effect of retention time on the crystal grain size of a conventional alloy (AC4CH).

FIG. 11 is a graph showing the influence of the degree of superheat (with respect to the liquidus) and the holding time (from the initial temperature in the heat insulating container to the liquidus temperature) on the crystal grain size in the conventional alloy (AZ91).

FIG. 12 is a graph showing the influence of the degree of superheat (with respect to the liquidus) and the holding time (from the initial temperature in the heat insulating container to the liquidus temperature) on the crystal grain size in the conventional alloy (AC4CH).

FIG. 13 shows the holding time (from the initial temperature in the adiabatic container to the liquidus temperature −) of the holding time on the crystal grain size in the conventional alloy (AZ91).
FIG.

FIG. 14 is a graph showing the effect of the holding time (from the initial temperature in the heat insulating container to the liquidus temperature −5 ° C.) on the crystal grain size of the conventional alloy (AC4CH).

[Explanation of symbols]

 Reference Signs List 10 ladle 20 jig 30 insulated container (ceramic container) 30A ceramic-coated metal container 40 injection sleeve 50 mold 50A mold cavity M metal (molten metal) t temperature T time

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasunori Harada 1980, Ogishi-kogashi-oki, Ube City, Ube City, Yamaguchi Prefecture Ube Industries, Ltd. Machinery and Engineering Business Division Examiner Takeshi Ogawa (56) (JP, A) JP-A-7-164108 (JP, A) JP-A-8-60267 (JP, A) JP-A-8-325652 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) C22C 1/02 B22D 17/00-17/32 B22D 27/00-27/20

Claims (2)

(57) [Claims] 1. A liquidus line obtained by pouring a molten metal of an aluminum alloy or a magnesium alloy having a superheat degree of less than 100 ° C. with respect to a liquidus temperature directly into an insulated container without using a jig. A molding method for molding an alloy in a liquid state having a crystal nucleus having a superheat degree (X ° C.) of less than 10 ° C. by a high-pressure casting method, an extrusion method, or a forging method, wherein the liquid phase ratio of the alloy is a high-pressure casting method. Is cooled in an insulated container for 5 seconds to 60 minutes to a molding temperature showing a liquidus ratio of 20 to 90%, and a liquid phase ratio of 0.1 to 70% in an extrusion method or a forging method. Y = 1 up to liquidus temperature
The temperature is decreased in a time shorter than the time (Y minute) calculated by the relational expression of 0-X, and a section of a temperature lower than the liquidus temperature by 5 ° C. from the initial temperature in the insulated container within 15 minutes. A method for forming a semi-molten metal, which comprises lowering the temperature to crystallize a fine primary crystal in the alloy liquid, supplying the alloy to a molding die and performing pressure molding. 2. A crystal nucleus obtained by pouring a melt of an aluminum alloy or a magnesium alloy having a degree of superheat to a liquidus temperature of less than 100 ° C. directly into an insulated container without using a jig. A molding method for molding an alloy in a solid-liquid coexisting state at a molding temperature or higher by a high pressure casting method, an extrusion method or a forging method, wherein the liquid phase ratio of the alloy is 20 to 90% when the liquid phase ratio is a high pressure casting method. 0.1-7 for forging
In the step of cooling in an insulated container for 5 seconds to 60 minutes to a molding temperature showing a liquidus ratio of 0%, a section of a temperature 5 ° C. lower than the liquidus temperature from the initial temperature in the insulated container is set to 15 minutes. A method for forming a semi-molten metal, which comprises lowering the temperature within minutes to crystallize fine primary crystals in the alloy liquid, supplying the alloy to a molding die, and performing pressure molding.