JP2001047213A - Die casting method of magnesium alloy and die casting product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a die casting product suitable to car engine parts needing high temp. strength and room temp. strength and without developing hot- cracking, shrinkage-crack and shrinkage-hole by regulating the molten metal temperature, filling speed into a cavity and increasing pressure after filling, of magnesium alloy having specified ratios of Al, rare earth elements, Ca, Si, Mn to the respective specified ranges. SOLUTION: This die casting method is executed by using a cold chamber type die casting machine and casting the die casting product without developing the hot-creaking, shrinkage-crack and shrinkage-hole from the magnesium alloy composed of at least one kind selected from group of 1-10 mass % aluminum, 0.2-5 mass % rare earth elements, 0.02-5 mass % calcium and 0.2-10 mass % silicon, and <=1.5 mass % manganese and the balance magnesium with inevitable impurities. Then, the molten metal temp. of the magnesium alloy is held to 650-750 deg.C, the filling speed into the cavity is made to 1/100-10/100 sec and the increased pressure after filling is made to >=200 kgf/cm2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die casting method and a die casting product of a magnesium alloy excellent in room temperature strength and high temperature strength, and more particularly, to about 523 K required for weight reduction of automobile engine parts and the like. The present invention relates to a die casting method and a die casting product of a magnesium alloy having sufficient strength even at a high temperature.

[0002]

2. Description of the Related Art In recent years, awareness of global environmental conservation has increased,
The demand for improving the fuel efficiency of automobiles has increased, and the development of lightweight materials for automobiles has been strongly demanded. Magnesium alloys have the lowest density among currently used metal materials, and are expected to be used as lightweight materials for automobiles in the future. At present, the most commonly used magnesium alloy is a Mg-Al-Zn-Mn alloy, for example, AZ91.
Alloys (Mg-9Al-0.7Zn-0.2Mn) or AM50 alloys (Mg-5Al-0.2Mn). The peripheral technologies such as casting technology of these alloys are in the stage of completion, and in order to reduce the weight of automobiles First, this alloy is being studied.

However, these alloys have reduced strength at 393K or higher, and are not suitable for applications such as engine parts which require heat resistance and cleave resistance up to about 473K. Therefore, alloys to which silicon is added for such applications, for example, AS41 alloy (Mg-4Al-1Si-0.2M
n), an alloy to which a rare earth element is added, for example, an AE42 alloy (Mg-4Al-2RE-0.2Mn) has been developed, and more recently, an alloy to which calcium has been added (Japanese Patent Laid-Open No. 6-2).
No. 5790), an alloy to which calcium and a rare earth element are added (Japanese Patent Application Laid-Open No. Hei 6-200348, Japanese Patent Application Laid-Open No. 7-1)
No. 1347) has been developed and proposed.

[0004]

All of these alloys are 473K or 5K required for automobile engine parts.
Although the alloy has improved heat resistance and creep resistance up to about 23K, except for a part, it has not been widely used. The reason is that these alloys are liable to generate hot cracks, shrinkage cracks, shrinkage cavities, and have problems such as entrapment of oxides and generation of wrinkles on the casting surface.
It is presumed that these are caused by the fact that silicon, rare earth elements, calcium, etc. are active, so that oxides are easily generated, and compounds are generated in the grain boundary portion, so that they are highly sensitive to hot cracking and shrinkage cracking. This is because the casting conditions under which measures were taken based on these problems were not disclosed.

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention provides a magnesium alloy for high temperature suitable for manufacturing automobile engine parts which require both high temperature strength and room temperature strength. Therefore, an object of the present invention is to provide a die casting method and a die casting product for casting a die casting product having no hot cracks, shrinkage cracks, and shrinkage cavities using a cold chamber type die casting machine.

[0006]

Means for Solving the Problems The present inventors have conducted various studies in order to achieve the above-mentioned object, and as a result, a magnesium alloy having a specific alloy composition has been subjected to a specific casting condition using a cold chamber type die casting machine. By casting a die-cast product underneath, it is possible to prevent hot cracks, shrinkage cracks and shrinkage cavities that have conventionally occurred when casting magnesium alloys for high temperatures, entrapment of oxides, generation of wrinkles on the casting surface, etc. The present inventors have found that the above problem can be solved and completed the present invention.

That is, the die casting method of the magnesium alloy according to the present invention comprises: i) 1 to 10% by mass of aluminum, ii) 0.2 to 5% by mass of a rare earth element, and 0.02% of calcium.
At least one selected from the group consisting of -5% by mass, and 0.2-10% by mass of silicon; and iii) a magnesium alloy containing 1.5% by mass or less of manganese, with the balance being magnesium and unavoidable impurities. A method of casting a die-cast product having no hot cracks, shrinkage cracks or shrinkage cavities using a cold chamber type die-casting machine, comprising: a) maintaining a temperature of a molten magnesium alloy at 650 to 750 ° C .; Filling speed 1/100 to 10/10
0 seconds; and c) the pressure increase after filling is 200 kgf / cm ² or more.

Further, the die casting method of the magnesium alloy of the present invention comprises the following steps: i) 1 to 10% by mass of aluminum; ii) 0.2 to 5% by mass of a rare earth element;
At least one selected from the group consisting of -5% by mass, and 0.2-10% by mass of silicon; and iii) a magnesium alloy containing 1.5% by mass or less of manganese, with the balance being magnesium and unavoidable impurities. A method of casting a die-cast product having no hot cracks, shrinkage cracks or shrinkage cavities by using a cold-chamber type die-casting machine. D) Maintaining the mold temperature at 150 to 350 ° C .; The surface temperature of the mold in the cavity where cracks are likely to occur is reduced by 10 K or more compared with the peripheral part. F) The air pressure in the mold during die casting is reduced to 100 mmH.
g) and g) at least one selected from the group consisting of graphite, BN, water glass, mica, silica gel, magnesium hydroxide and magnesium oxide as an additive to the mold release agent applied to the inner surface of the mold. And

Further, the die casting method of the magnesium alloy of the present invention comprises the following steps: i) 1 to 10% by mass of aluminum; ii) 0.2 to 5% by mass of a rare earth element;
At least one selected from the group consisting of -5% by mass, and 0.2-10% by mass of silicon; and iii) a magnesium alloy containing 1.5% by mass or less of manganese, with the balance being magnesium and unavoidable impurities. A method of casting a die-cast product having no hot cracks, shrinkage cracks or shrinkage cavities by using a cold-chamber type die-casting machine. H) A closed type melting in which a protective atmosphere for preventing combustion and oxidation is formed on the surface of the magnesium alloy melt. Using a furnace, and i) pumping out the magnesium alloy melt from a position at least 100 mm from the surface of the alloy melt to suppress oxidation of the magnesium alloy melt, improve the fluidity of the melt, It is characterized in that entrainment and generation of hot water wrinkles are suppressed.

Further, the die casting method of the magnesium alloy according to the present invention comprises: i) 1 to 10% by mass of aluminum; ii) 0.2 to 5% by mass of a rare earth element;
At least one selected from the group consisting of -5% by mass, and 0.2-10% by mass of silicon; and iii) a magnesium alloy containing 1.5% by mass or less of manganese, with the balance being magnesium and unavoidable impurities. A method of casting a die-cast product having no hot cracks, shrinkage cracks or shrinkage cavities using a cold chamber type die-casting machine, comprising: a) maintaining a temperature of a molten magnesium alloy at 650 to 750 ° C .; Filling speed 1/100 to 10/10
0) and c) Injection conditions for increasing the pressure after filling to 200 kgf / cm ² or more; d) Maintaining the mold temperature at 150 to 350 ° C .; e) Cavities that easily cause cracks in the die-cast products The surface temperature of the mold at the site is reduced by 10 K or more compared with the surrounding area. F) The air pressure in the mold during die casting is reduced to 100 mmH.
g) Mold conditions using at least one selected from the group consisting of graphite, BN, water glass, mica, silica gel, magnesium hydroxide and magnesium oxide as an additive to a mold release agent applied to the inner surface of the mold. And h) using a closed melting furnace in which a protective atmosphere for preventing combustion and oxidation is formed on the surface of the molten magnesium alloy, and i) pumping out the molten magnesium alloy from a position at least 100 mm away from the surface of the molten alloy. By suppressing the oxidation of the magnesium alloy melt by improving the flowability,
Any two of the three conditions consisting of magnesium alloy dissolution conditions for suppressing entrapment of oxides and generation of hot water wrinkles
It is characterized by die casting using a combination of three or three kinds of conditions.

Further, the die-cast product of the present invention is a magnesium alloy die-cast product which can be produced by any one of the above-mentioned die-casting methods and has no hot crack, shrinkage crack or shrinkage cavity. Incidentally, in the present invention, the die-cast product,
Die casting parts are also included.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The composition of a magnesium alloy used in the die casting method of the present invention, injection conditions, die conditions, melting conditions of the magnesium alloy, and the like in the die casting method will be described in detail below.

The magnesium alloy used in the die casting method of the present invention comprises: i) 1 to 10% by mass of aluminum, ii) 0.2 to 5% by mass of a rare earth element, and 0.02% of calcium.
-5% by mass, and at least one selected from the group consisting of silicon 0.2-10% by mass, and iii) a magnesium alloy containing manganese 1.5% by mass or less, with the balance being magnesium and unavoidable impurities. Yes, for example, Mg-5Al-2Ca-2RE-0.2M
n, Mg-5Al-4Ca-0.2Mn, Mg-5Al
-4RE-0.2Mn, Mg-5Al-8Si-0.2
Mn, Mg-9Al-2RE-1Si-0.05Ca-
0.02Mn, Mg-5Al-0.5RE-0.1Si
-0.1Ca-0.02Mn, Mg-2Al-2Ca-
0.2 Mn or the like can be used.

In the die casting method of the present invention, a cold chamber type die casting machine is used. The reason for using the cold chamber type die casting machine in the present invention is that in the hot chamber type die casting machine, since the injection member made of iron is immersed in the molten metal, the rare earth element having a high affinity for iron, reacts with the alloy containing calcium. However, this is because problems such as sticking of the plunger to the sleeve are likely to occur. Particularly, a magnesium alloy having a low aluminum content, for example, a magnesium alloy having an aluminum content of 2 to 6% by mass is often used.
In this case, casting is generally difficult in a hot chamber type die casting machine.

Injection conditions in the die casting method of the present invention include a molten metal temperature. Melt temperature in melting furnace is 650
If the temperature is lower than ℃, the fluidity is reduced and there is a problem in the filling property to the mold. On the other hand, if the temperature exceeds 750 ° C., the danger of ignition at the time of holding the molten metal increases, and the shrinkage rate from the molten metal to the solidification increases, so that hot cracks and shrinkage cracks easily occur. Therefore, the temperature of the molten alloy must be maintained at 650 to 750 ° C, preferably 650 to 710 ° C.

Injection conditions in the die casting method of the present invention include a cavity filling speed. In general, magnesium alloys have a low latent heat of solidification, so it is recommended to increase the injection speed. In the magnesium alloy used in the present invention, a compound is likely to be generated at a grain boundary portion where solidification is relatively delayed, so that cracks easily occur. Therefore, casting pressure must be applied to the entire casting. Therefore, the balance between casting speed and cooling from the mold should be considered,
Empirically, the filling speed in the mold catty is 1 / 100-
It is a necessary condition that the time is set to be 10/100 seconds, preferably 1/100 to 5/100 seconds. In order to satisfy such a condition, the injection speed is set to 2 m / sec or more, preferably 3.5 m / sec or more, or the gate speed is set to 30 m / sec.
sec or more, preferably 50 m / sec or more. When the filling speed into the mold catty is lower than 10/100 seconds, a problem occurs in either the filling property (poor filling) or the hot cracking property.

Injection conditions in the die casting method of the present invention include pressure increase after filling. Immediately after filling into the mold cavity, the pressure must be further increased to prevent poor filling, and to suppress the occurrence of hot cracking and shrinkage cracks during solidification and cooling. The pressure increasing condition at this time was 200 kgf / cm ²
As described above, it is desirably 400 kgf / cm ² or more. If such pressure increase is not applied, poor filling occurs or cracks occur over the entire area of the casting where the thickness changes.

The above-described die casting injection conditions are related to each other, and even if one of these conditions is missing, a sound thin cast of a magnesium alloy cannot be obtained. Conversely, these three injection conditions, namely: a) maintaining the temperature of the molten magnesium alloy at 650 to 750 ° C., and b) reducing the filling rate of the cavity to 1/100 to 10/10
0 seconds, and c) satisfying the condition that the pressure increase after filling is 200 kgf / cm ² or more,
Magnesium alloy die casting without shrinkage cavities can be cast.

The mold temperature in the die casting method of the present invention is a mold temperature. When the mold temperature is lower than 150 ° C., the filling property of the molten metal is empirically hindered, or even if the filling can be performed, there is a problem in the surface properties such as hot water wrinkles. On the other hand, when the temperature exceeds 350 ° C., shrinkage cracks and hot cracks are likely to occur due to a slow solidification rate. Therefore, the mold temperature is set to 150 to 350 ° C, preferably 180 to 280 ° C.
To hold.

In the die casting method of the present invention, a mold condition is local cooling. Depending on the shape of the casting, there are portions where cracks are likely to occur in shape, such as a sudden change in thickness. In such a case, local temperature control is required in addition to the overall mold temperature control described above. In order to control the temperature, a coolant passage is provided at a necessary portion of the mold, and a coolant such as water, oil, air, or the like is passed through the passage to locally cool the mold, or the mold is opened when the mold is opened. There is a method of locally cooling by spraying a molding agent or air, but in any case, the surface temperature of a part of the mold requiring local cooling is cooled by 10 K or more, preferably 20 K or more from the surrounding surface temperature, It is necessary to preferentially solidify a portion where a crack is likely to occur to prevent a crack.

The die conditions in the die casting method of the present invention include a reduced pressure in the die. In order to assist the filling of the molten metal into the cavity and at the same time prevent the flow of the molten metal from being disturbed by air in the die, depressurization in the die is necessary. In order to achieve this object, the air pressure in the mold at the time of injecting the molten metal needs to be 100 mmHg or less, preferably 50 mmHg or less.

The mold conditions in the die casting method of the present invention include a release agent applied to the inner surface of the mold. Regarding the cooling condition for solidification, not only the temperature condition of the mold but also the casting pressure can be made effective by delaying the solidification by the heat retaining effect of the release agent. In order to achieve this object, it is effective to use at least one selected from the group consisting of graphite, BN, water glass, mica, silica gel, magnesium hydroxide and magnesium oxide as an additive of the release agent.

The above mold conditions are related to each other,
Mold temperature is particularly important. If there is no cavity site in the die-cast product that is susceptible to cracking, local cooling is not required, in which case local cooling is excluded from the requirements of the present invention. Depending on the shape of the cavity and the shape of the die-cast product, the pressure reduction in the mold and the additive of the release agent are not necessarily required. However, it is preferable to use such constituents in combination, since better results can be obtained.

In the present invention, these four types of mold conditions, namely, d) the mold temperature is maintained at 150 to 350 ° C., and e) the mold at the cavity portion where cracks are easily generated in the die-cast product. The surface temperature of the mold is reduced by 10K or more compared with the peripheral part. F) The air pressure in the mold at the time of die casting is reduced to 100 mmH.
g) and g) at least one selected from the group consisting of graphite, BN, water glass, mica, silica gel, magnesium hydroxide and magnesium oxide as an additive to a mold release agent applied to the inner surface of the mold. Satisfaction makes it possible to cast a magnesium alloy die-cast free of hot cracks, shrinkage cracks and shrinkage cavities.

The magnesium alloy used in the present invention contains one or more of rare earth elements, calcium and silicon, and all of these elements are active and thus increase the flammability and oxidizability of the magnesium alloy. Therefore, as a melting condition of the magnesium alloy in the die casting method of the present invention, a protective atmosphere for preventing combustion and oxidation may be provided on the surface of the molten magnesium alloy. For this purpose, a closed melting furnace is used in which a protective atmosphere for preventing combustion and oxidation is formed on the surface of the molten magnesium alloy. As the combustion / oxidation prevention protective atmosphere, for example, a gas in which at least one of SF ₆ and SO ₂ is added to a gas such as dry air, CO ₂ , and N _{2 at} a concentration of 0.1% by volume or more, or Ar,
Inert gases such as CO ₂ , He, Ne, N ₂ , and dry air can be given to the magnesium alloy melt, and these are circulated on the surface of the magnesium alloy melt. In the open type melting furnace, the magnesium alloy melt is oxidized, and the oxidization generated by the oxidation causes entrapment of the oxide and deterioration of the fluidity.

When carrying out die casting using a cold chamber type die casting machine, it is necessary to pump out molten metal from a melting furnace and carry it to a sleeve portion of the cold chamber type die casting machine. If the melt is pumped out from the surface of the melt, oxides and dross may be entrained.

As a condition for dissolving the magnesium alloy in the die casting method of the present invention, the molten metal is pumped out from a position at least 100 mm away from the surface using a tube in order to avoid the surface portion where the oxide floats. To prevent entanglement. In addition, it is preferable to prevent the entrainment of the intermetallic compound or the like by performing from a position 100 mm or more from the bottom where the intermetallic compound or the like is deposited. The term "tube" used herein includes a tube in a pumping section of an automatic water heater such as a siphon or a mechanical pump.

As a condition for melting the magnesium alloy in the die casting method of the present invention, there is a surface coating of a melting pot. The molten magnesium alloy has a high reactivity with iron and the active oxidation of the molten metal at the pot surface and the contact area between the molten metal and the air. Therefore, the surface of the molten pot, especially the surface of the pot in contact with the molten metal surface The part is plated with aluminum, BN or TiN is applied or sprayed, or both are performed to suppress the reaction between the magnesium alloy melt and iron, reduce the wettability between the pot and the melt, and reduce the pot and the melt. Suppresses the oxidation of the molten metal at the contact portion.

Although the above-described melting conditions of the magnesium alloy are related to each other, the surface coating of the pot is not essential because the entanglement of the oxide is prevented by performing the pumping of the molten metal as described above. However, it is preferable to use such constituents in combination, since better results can be obtained.

In the present invention, these mold conditions, ie, h) using a closed melting furnace in which a protective atmosphere for preventing combustion and oxidation is formed on the surface of the magnesium alloy melt, i) pumping out the magnesium alloy melt From a position at least 100 mm from the surface of the molten alloy, and if desired, j) aluminum plating on the surface of the molten pot, particularly on the pot surface in contact with the molten metal surface, or BN, Ti
By applying and / or spraying N, the oxidation of the molten magnesium alloy is suppressed, the fluidity is improved, the entrapment of oxides and the generation of hot water wrinkles can be suppressed, and hot cracking, Magnesium alloy die casting without shrinkage or shrinkage cavities can be cast.

The magnesium alloy die-casting method of the present invention can be applied to any two or three of the three conditions of the above-described injection condition, mold condition, and melting condition of the magnesium alloy.
Die casting can be performed using a combination of conditions, and in these cases better results are obtained.

[0032]

The present invention will be specifically described below based on examples and comparative examples. In the following Examples and Comparative Examples, as magnesium alloys, alloy 1 = Mg-5Al-2Ca-2RE-0.2Mn, alloy 2 = Mg-5Al-4Ca-0.2Mn, alloy 3 = Mg-5Al-4RE -0.2Mn, Alloy 4 = Mg-5Al-8Si-0.2Mn, Alloy 5 = Mg-9Al-2RE-1Si-0.05Ca
-0.02Mn, Alloy 6 = Mg-5Al-0.5RE-0.1Si-0.
One of 1Ca-0.02Mn and alloy 7 = Mg-2Al-2Ca-0.2Mn was used.

Examples 1 to 7 and Comparative Examples 1 to 4 Alloy 1 was used as Example 1, a 650 t machine made by Ube was used as a cold chamber type die casting machine, the temperature of the molten alloy was set at 700 ° C., and the filling rate of the cavity was adjusted. 5/100
Second, the pressure increase after filling is 500 kgf / cm ² , the mold temperature is 200 ° C., and the air pressure in the mold during die casting is 50 m.
300 mm x 300 simulating automobile parts as mHg
A box-shaped prototype having a size of 180 mm and a thickness of 3 mm was cast. The casting results were as shown in Table 1. Examples 2 to 7 and Comparative Examples 1 to 4 in which the casting conditions were changed from the above-mentioned standards as shown in Table 1 (the casting conditions not described in Table 1 were kept as described above and were not changed). Was carried out. The results of the castings were as shown in Table 1.

[0034]

Examples 8 to 12 and Comparative Examples 5 to 9 Alloy 1 was used in Example 8, and a 650 t machine made by Ube was used as a cold chamber die casting machine. In order to make the die-cast product easily crackable, the thickness of the box-shaped prototype of Example 1 was reduced from 3 mm to 1 at the four corners of the box bottom.
A portion changing to 0 mm was provided.

The temperature of the molten alloy is 700 ° C., the filling speed in the cavity is 5/100 seconds, and the pressure after filling is 500 kgf.
/ Cm ² , the standard mold temperature is 250 ° C., the mold temperature of the thickness change portion is 230 ° C. by local cooling of the mold, the air pressure in the mold at the time of die casting is 50 mmHg, and the inner surface of the mold is A talc release agent (manufactured by Hanano Shoji) was applied to cast a box prototype. The casting results were as shown in Table 2. Examples 9 to 12 and Comparative Example 5 in which the casting conditions were changed from the above-mentioned standards as shown in Table 2 (the conditions not described in Table 2 were not changed and were as described above).
To 9 were performed. The results of the castings are as shown in Table 2.

[0037]

The talc-based release agent to which graphite, BN, water glass, mica, silica gel or magnesium hydroxide was added instead of the MgO-added talc-based release agent used in Example 12 was applied. Was die-cast under the same conditions as in Example 12, but no seizure occurred in any case.

Examples 13 to 15 and Comparative Examples 10 to 11 As Example 13, alloy 1 was melted using a closed melting furnace, the temperature of the molten metal was maintained at 700 ° C., and
Dry air containing SF ₆ at a concentration of 0.2% by volume was passed through. The molten metal was pumped out through a pipe from a position 150 mm away from the molten metal surface, and supplied to a cold chamber type die casting machine (a 650 t machine made by Ube).
The filling speed of the cavity is 5/100 seconds, the pressure increase after filling is 500 kgf / cm ² , the mold temperature is 250 ° C., the mold temperature of the thickness change portion is 230 ° C. by local cooling of the mold, and die casting is performed. The air pressure in the mold at the time is 50 mmHg,
A talc-based release agent (manufactured by Hanano Shoji Co., Ltd.) was applied to the inner surface of the mold, and a box prototype identical to the box mold of Example 1 was cast. The casting results were as shown in Table 3. The casting conditions were changed from the above standard as shown in Table 3 (No. 3).
Examples 14 to 15 and Comparative Examples 10 to 11 were carried out without changing the conditions not described in the table. The results of the castings are as shown in Table 3.

[0040]

[0041]

According to the present invention, calcium / rare-earth elements suitable for manufacturing automobile engine parts requiring both high-temperature strength and room-temperature strength by specifying injection conditions, mold conditions, or melting conditions in a cold chamber type die casting machine. Die-cast products without hot cracks, shrinkage cracks or shrinkage cavities can be die-cast from high-temperature magnesium alloys containing elements and silicon.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B22D 17/32 B22D 17/32 A B // B22C 9/06 B22C 9/06 D (72) Inventor Yamamoto Yu 1200, Shimojo Nishiwari, Ogusa-cho, Nirasaki City, Yamanashi Prefecture Inside Mitsui Kinzoku Mining Co., Ltd. 1200, Shimojo Nishiwari, Ogura-machi, Nirasaki-shi, Japan Mitsui Kinzoku Mining Co., Ltd. (72) Inventor Takeshi Doi 1200 Shimojo-Nishiwari, Ogaku-cho, Nirasaki, Yamanashi Prefecture F-term in Mitsui Kinzoku Mining Co., Ltd. 4E093 NB05 NB09

Claims (5)

[Claims] 1. i) 1 to 10% by mass of aluminum; ii) 0.2 to 5% by mass of a rare earth element, 0.02% of calcium
At least one selected from the group consisting of -5% by mass, and 0.2-10% by mass of silicon; and iii) a magnesium alloy containing 1.5% by mass or less of manganese, with the balance being magnesium and unavoidable impurities. A method of casting a die-cast product having no hot cracks, shrinkage cracks or shrinkage cavities using a cold chamber type die-casting machine, comprising: a) maintaining a temperature of a molten magnesium alloy at 650 to 750 ° C .; Filling speed 1/100 to 10/10
A die casting method of a magnesium alloy, wherein the pressure is increased to 200 kgf / cm ² or more after filling for 0 second and c). 2. i) 1 to 10% by weight of aluminum; ii) 0.2 to 5% by weight of a rare earth element, 0.02% of calcium
At least one selected from the group consisting of -5% by mass, and 0.2-10% by mass of silicon; and iii) a magnesium alloy containing 1.5% by mass or less of manganese, with the balance being magnesium and unavoidable impurities. A method of casting a die-cast product having no hot cracks, shrinkage cracks or shrinkage cavities by using a cold-chamber type die-casting machine. D) Maintaining the mold temperature at 150 to 350 ° C .; The surface temperature of the mold in the cavity where cracks are likely to occur is reduced by 10 K or more compared with the peripheral part. F) The air pressure in the mold during die casting is reduced to 100 mmH.
g) and g) at least one selected from the group consisting of graphite, BN, water glass, mica, silica gel, magnesium hydroxide and magnesium oxide as an additive to the mold release agent applied to the inner surface of the mold. Die casting of magnesium alloy. 3. i) 1 to 10% by weight of aluminum, ii) 0.2 to 5% by weight of rare earth element, 0.02% of calcium
At least one selected from the group consisting of -5% by mass, and 0.2-10% by mass of silicon; and iii) a magnesium alloy containing 1.5% by mass or less of manganese, with the balance being magnesium and unavoidable impurities. A method of casting a die-cast product having no hot cracks, shrinkage cracks or shrinkage cavities by using a cold-chamber type die-casting machine. H) A closed type melting in which a protective atmosphere for preventing combustion and oxidation is formed on the surface of the magnesium alloy melt. Using a furnace, and i) pumping out the magnesium alloy melt from a position at least 100 mm from the surface of the alloy melt to suppress oxidation of the magnesium alloy melt, improve the fluidity of the melt, A die casting method of a magnesium alloy, which suppresses entrainment and generation of hot water wrinkles. 4. i) 1 to 10% by weight of aluminum, ii) 0.2 to 5% by weight of rare earth element, 0.02% of calcium
At least one selected from the group consisting of -5% by mass, and 0.2-10% by mass of silicon; and iii) a magnesium alloy containing 1.5% by mass or less of manganese, with the balance being magnesium and unavoidable impurities. A method of casting a die-cast product having no hot cracks, shrinkage cracks or shrinkage cavities using a cold chamber type die-casting machine, comprising: a) maintaining a temperature of a molten magnesium alloy at 650 to 750 ° C .; Filling speed 1/100 to 10/10
0) and c) Injection conditions for increasing the pressure after filling to 200 kgf / cm ² or more; d) Maintaining the mold temperature at 150 to 350 ° C .; e) Cavities that easily cause cracks in the die-cast products The surface temperature of the mold at the site is reduced by 10 K or more compared with the surrounding area. F) The air pressure in the mold during die casting is reduced to 100 mmH.
g) Mold conditions using at least one selected from the group consisting of graphite, BN, water glass, mica, silica gel, magnesium hydroxide and magnesium oxide as an additive to a mold release agent applied to the inner surface of the mold. And h) using a closed melting furnace in which a protective atmosphere for preventing combustion and oxidation is formed on the surface of the molten magnesium alloy, and i) pumping out the molten magnesium alloy from a position at least 100 mm away from the surface of the molten alloy. By suppressing the oxidation of the magnesium alloy melt by improving the flowability,
Any two of the three conditions consisting of magnesium alloy dissolution conditions for suppressing entrapment of oxides and generation of hot water wrinkles
A die casting method for a magnesium alloy, comprising die casting using a combination of three or three kinds of conditions. 5. A magnesium alloy die-cast product having no hot crack, shrinkage crack or shrinkage cavities, which can be produced by the die-casting method according to claim 1.