KR20210076329A - Aluminium alloy for die casting and manufacturing method for aluminium alloy casting using the same - Google Patents

Abstract

The present invention relates to an aluminum alloy for die casting that can be used for parts requiring heat dissipation characteristics and high corrosion resistance by having both excellent thermal conductivity and corrosion resistance, and a manufacturing method of an aluminum alloy casting using the same. An aluminum alloy for die casting according to an embodiment of the present invention comprises 8.5 to 10.5 wt% of Si, 3.6 to 5.5 wt% of Mg, 0.3 to 1.0 wt% of Fe, 0.1 to 1.0 wt% of Mn, and the balance Al and other unavoidable impurities.

Description

Aluminum alloy for die casting and aluminum alloy casting manufacturing method using same {ALUMINIUM ALLOY FOR DIE CASTING AND MANUFACTURING METHOD FOR ALUMINIUM ALLOY CASTING USING THE SAME}

The present invention relates to an aluminum alloy for die casting and a method for manufacturing an aluminum alloy casting using the same, and more particularly, to an aluminum alloy for die casting that has excellent thermal conductivity and corrosion resistance and can be used for parts requiring heat dissipation characteristics and high corrosion resistance, and It relates to a method for manufacturing an aluminum alloy casting using the same.

In general, aluminum (Al) is widely used throughout the industry because it is easy to cast, alloys well with other metals, has strong corrosion resistance in the atmosphere, and has excellent electrical and thermal conductivity.

In particular, in recent years, aluminum is widely used to reduce vehicle weight and improve fuel efficiency, and since aluminum itself does not have high strength compared to other metals, an aluminum alloy in which aluminum is mixed with other metals is often used. .

Die casting is widely used as a method for producing products using such an aluminum alloy. In die casting, molten metal is injected into a mold in which a cavity is precisely machined according to the required casting shape to have the same shape as the cavity. It is a precision casting method to obtain castings.

The aluminum alloy for die casting must have properties that match the characteristics of the method of solidifying the high-speed and high-pressure molten metal by filling the cavity at high pressure into the mold. That is, by providing an appropriate level of high-temperature viscosity and latent heat, it must have fluidity suitable for high-pressure casting and must be able to compensate for shrinkage defects that may occur during solidification.

Currently widely used aluminum alloys for die casting include Al-Si alloys such as ADC 3, ADC 10, and ADC 12, which have excellent castability, and Al-Mg alloys, such as 5 ADCs or 6 ADCs. However, these aluminum die-casting alloys have low heat dissipation and corrosion resistance, which limits the expansion of the application range.

On the other hand, the present applicant continued research on an aluminum alloy for die casting capable of improving thermal conductivity and corrosion resistance, and applied for (Patent Document 1).

However, (Patent Document 1) can be expected to improve the thermal conductivity and corrosion resistance to some extent, but there is a limit to the improvement of the thermal conductivity and corrosion resistance because the content ratio of Mg to the Si content is small.

The content described as the background art above is only for understanding the background of the present invention, and should not be taken as an acknowledgment that it corresponds to the prior art already known to those of ordinary skill in the art.

Laid-open Patent Publication No. 10-2019-0120487 (2019. 10. 24)

The present invention provides an aluminum alloy for die casting that can be used for parts requiring heat dissipation characteristics and high corrosion resistance by adjusting the content of Si Mg, Fe and Mn contained together with Al and having excellent thermal conductivity and corrosion resistance, and an aluminum alloy using the same A method for manufacturing a casting is provided.

In particular, the present invention provides an aluminum alloy for die casting capable of maintaining excellent castability and formability while maintaining excellent thermal conductivity and corrosion resistance by adjusting the content and ratio of Si and Mg, and a method for manufacturing an aluminum alloy casting using the same. .

The aluminum alloy for die casting according to an embodiment of the present invention is by weight %, Si: 7.8 to 10.5%, Mg: 3.6 to 5.5%, Fe: 0.3 to 1.0%, Mn: 0.1 to 1.0%, remaining Al and other inevitable contains impurities.

The aluminum alloy is characterized in that it further contains Be: 0.002 to 0.02%.

The aluminum alloy is characterized in that Si: 8.0 to 10.5%.

The aluminum alloy is characterized in that the ratio of Si/Mg is 1.5 or more and less than 3.0.

Among the impurities contained in the aluminum alloy, Cu, Zn and Ni are characterized in that the total content is 0.2% or less.

The aluminum alloy is characterized in that the yield strength is 260 MPa or more.

The aluminum alloy is characterized in that the tensile strength is 320 MPa or more.

The aluminum alloy is characterized in that the elongation is 2.0 to 3.0%.

The aluminum alloy is characterized in that the thermal conductivity is 135 w/m.K or more.

The aluminum alloy is characterized in that the electrical conductivity is 30% IACS or more.

On the other hand, the method for manufacturing an aluminum alloy casting according to an embodiment of the present invention comprises: an Al melt preparation step of dissolving Al or Al scrap to prepare an Al melt; A first temperature raising step of raising the temperature of the prepared Al melt; A first alloying step of preparing a first alloy melt by adjusting the content of Si in the heated Al melt to 7.8 to 10.5%; a second temperature raising step of raising the temperature of the first alloy melt; A secondary alloying step of preparing a secondary alloy melt by adjusting the content of Fe to 0.3 to 1.0% in the heated primary alloy melt, and adjusting the content of Mn to 0.1 to 1.0%; a temperature reduction step of reducing the temperature of the secondary alloy melt; It includes a tertiary alloying step of preparing a tertiary alloy melt by adjusting the content of Mg in the reduced temperature secondary alloy melt to 3.6 to 5.5%.

In the first alloying step, the content of Si is adjusted to 8.0 to 10.5% to prepare a first alloy melt.

In the second alloying step, Be: 0.002 to 0.02% of the heated primary alloy melt is further added.

The first temperature raising step raises the temperature of the Al melt to 800 ~ 850 °C, the second temperature increase step raises the temperature of the primary alloy melt to 900 ~ 950 °C, and the temperature reduction step heats the secondary alloy melt to 700 ~ 750 °C. It is characterized in that the temperature is reduced.

The method further includes a casting step of manufacturing an aluminum alloy casting by injecting a tertiary alloy melt into a mold.

The casting step is characterized in that the tertiary alloy melt is injected into the die casting mold at 680 ~ 750 °C.

According to an embodiment of the present invention, various castings used in the manufacture of automotive electronic parts and portable electronic devices requiring heat dissipation characteristics and high corrosion resistance by securing excellent thermal conductivity and corrosion resistance compared to conventional aluminum alloy for die casting are manufactured There is an effect that can be done.

In addition, there is an effect that can manufacture a casting having superior strength and elongation compared to the conventional aluminum alloy for general die casting.

1 and 2 are photographs comparing the salt spray test results for Comparative Examples and Examples of the present invention,
3 is a photograph showing a microstructure according to a comparative example and an embodiment of the present invention;
4 is a photograph showing the microstructure of a specimen according to a comparative example and an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and the scope of the invention to those of ordinary skill in the art will be completely It is provided to inform you.

The aluminum alloy for die casting according to an embodiment of the present invention is, by weight%, silicon (Si): 7.8 to 10.5%, magnesium (Mg): 3.6 to 5.5%, iron (Fe): 0.3 to 1.0%, manganese (Mn) ): 0.1 to 1.0%, including the remaining aluminum (Al) and other unavoidable impurities. And, beryllium (Be): 0.002 to 0.02% may be further contained.

In addition, the aluminum alloy for die casting according to an embodiment of the present invention does not optionally contain copper (Cu), zinc (Zn) and nickel (Ni). However, the aluminum alloy may contain copper (Cu), zinc (Zn) and nickel (Ni) as unavoidable impurities. However, even when copper (Cu), zinc (Zn) and nickel (Ni) are contained as impurities, it is desirable to manage the total content to be 0.2% or less.

The reason for limiting the alloy component and its composition range in the present invention is as follows. Hereinafter, unless otherwise specified, % described in units of the composition range means weight %.

Silicon (Si): 7.8 ~ 10.5%

Silicon (Si) is a major element that improves castability and wear resistance and affects thermal conductivity and strength.

At this time, if the content of silicon (Si) is less than 7.8%, the effect of improving castability, wear resistance, and strength is insignificant, and if it exceeds 10.5%, the machinability such as machinability of the manufactured casting may be reduced and heat treatment may be weakened, so it is limited to the above range. .

In particular, silicon (Si) is an essential additive element for securing fluidity and formability of the molten metal during the die casting process. Corrosion resistance is improved as the content of magnesium (Mg), which will be described later, increases, but as the content of magnesium (Mg) increases, formability and fluidity are significantly deteriorated. To compensate for this, the molten metal temperature must be increased during the die casting process to manufacture products. Do. However, when the molten metal temperature rises, product hot cracks occur and the lifespan of the die-casting mold is shortened, resulting in reduced mass productivity and higher defect rates. In order to control this in the alloy, the Si content must be increased, and in this embodiment, the Si content is adjusted to 7.8 to 10.5% to secure corrosion resistance, castability, and mass productivity. Preferably, it is better to adjust the Si content to 8.0 to 10.5%, more preferably to adjust the Si content to 8.5 to 10.5%.

Magnesium (Mg): 3.6 ~ 5.5%

_{Magnesium (Mg) becomes a sacrificial corrosion site due to the Mg 2} Si crystallized phase generated by reacting with silicon (Si), which not only improves corrosion resistance, but also improves strength and elongation, and is a major factor in improving the workability of the casting. is an element

At this time, when the content of magnesium (Mg) is less than 3.6%, the effect of improving corrosion resistance, strength, and elongation is insignificant, and when it exceeds 5.5%, the fluidity of the molten metal during casting is lowered to decrease castability, and the oxidation tendency of the molten metal is reduced. It is limited to the above range because the dross is increased by increasing.

Iron (Fe): 0.3 ~ 1.0%

Iron (Fe) is an element that contributes to preventing mold burning and product scratching.

At this time, when the content of iron (Fe) is less than 0.3%, the strength improvement effect is insignificant, and when it exceeds 1.0%, corrosion resistance and thermal conductivity are lowered, and thus, it is limited to the above range.

Manganese (Mn): 0.1 ~ 1.0%

Manganese (Mn) is an element that contributes to solid solution strengthening together with iron (Fe) to improve the high-temperature strength of the casting, prevent mold burning, and improve solubility.

At this time, when the content of manganese (Mn) is less than 0.1%, the strength improvement effect is insignificant, and when it exceeds 1.0%, castability and machinability can be reduced and thermal conductivity can be reduced, so it is limited to the above range.

Beryllium (Be): 0.002 ~ 0.02%

Beryllium (Be) is an element that prevents oxidation of magnesium (Mg) to suppress dross formation during casting and improve corrosion resistance.

At this time, when the content of beryllium (Be) is less than 0.002%, the effect of improving corrosion resistance is insignificant, and when it exceeds 0.02%, corrosion resistance may be rather reduced, and thus, it is limited to the above range.

On the other hand, the remainder other than the above-mentioned components is aluminum (Al) and impurities contained inevitably.

In this case, in order to secure the corrosion resistance of the aluminum alloy to a desired level, it is preferable not to arbitrarily contain copper (Cu), zinc (Zn), and nickel (Ni), which are elements that cause corrosion. However, even when copper (Cu), zinc (Zn), and nickel (Ni) are unavoidably contained, it is desirable to manage the total content to be 0.2% or less.

In addition, in this embodiment, the Si/Mg ratio is limited to 1.5 or more and less than 3.0.

The reason is to properly generate _{Mg 2} Si, which is a corrosion resistance strengthening factor. In addition, the Si content was adjusted to prevent a decrease in castability and a decrease in mass production due to an increase in hot cracks and an increase in the defect rate compared to the improvement in corrosion resistance and strength due to an increase in Mg content, and thermal conductivity can be expected to increase through optimization of both components.

If the ratio of Si/Mg is less than 1.5, since the Si content is relatively small and the Mg content is increased, castability is deteriorated, and a problem of hot cracks occurring during casting occurs. In addition, when the ratio of Si/Mg exceeds 3.0, since the Si content is relatively increased and the Mg content is decreased, there is a problem that the improvement of corrosion resistance and strength is not reached to a desired level.

A method for manufacturing an aluminum alloy casting according to an embodiment of the present invention will be described.

First, an Al melt is prepared by dissolving Al or Al scrap at 750°C. (Al melt preparation step) In this case, it is preferable to use a high quality Al scrap in order to minimize the content of impurities in the Al scrap. For example, in order to suppress the content of Cu, which is a corrosion-resistance reducing element, to 0.15 wt% or less, it is recommended to use only high-quality Al scrap for aluminum wrought materials as Al scrap. Therefore, it is best not to use 1000 series, 6000 series and 7000 series Al scrap if possible.

Then, when Al or Al scrap is sufficiently dissolved and the Al melt is prepared, the temperature of the prepared Al melt is raised to 800 ~ 850 °C. (First temperature raising step)

When the Al melt is heated to 800 ~ 850℃, the content of Si in the Al melt is adjusted to 8.5 ~ 10.5% to prepare a first alloy melt in which Si is sufficiently dissolved. (First alloying step)

When the first alloy melt with the Si content in Al is prepared in this way, the temperature of the first alloy melt is raised to 900 ~ 950℃. (Second temperature increase step)

Then, the content of Fe is adjusted to 0.3 to 1.0% in the heated primary alloy melt, and the content of Mn is adjusted to 0.1 to 1.0% to prepare a secondary alloy melt. (Second alloying step)

At this time, the heated primary alloy melt can further adjust the content of Be to 0.002 to 0.02%.

In order to sufficiently dissolve Fe, Mn, and Be in the primary alloy melt, the elevated temperature is sufficiently maintained for about 5 hours.

So, when the secondary alloy melt is prepared, the temperature of the secondary alloy melt is reduced to 700 ~ 750 °C. (Temperature reduction step)

Then, the tertiary alloy melt is prepared by adjusting the Mg content to 3.6 ~ 5.5% in the second alloy melt at reduced temperature. (Third alloying step)

On the other hand, the temperature ranges suggested in the first temperature raising step, the second temperature increasing step and the temperature decreasing step are for the control of aluminum (Al) oxide and magnesium (Mg) oxide, and when it is outside the temperature range suggested in each step, unnecessary aluminum (Al) ) oxide and magnesium (Mg) oxide are generated, and accordingly, the desired physical properties cannot be achieved in the present invention because alloying is not performed evenly.

For example, if the temperature maintained in the temperature reduction step is lower than the suggested temperature, magnesium carbonate is generated in the tertiary alloying step, resulting in an unwanted yellow color of the aluminum alloy. And, when the temperature maintained in the temperature reduction step is higher than the suggested temperature, magnesium oxide is generated in the tertiary alloying step, resulting in an undesirable blue color of the aluminum alloy.

At this time, while maintaining the temperature of the tertiary alloy melt at 700 ~ 750 °C for about 1 hour, the temperature is gradually reduced. So, dross and oxides generated in the tertiary alloy melt are removed.

Controlling the content of each alloying element in the first to third alloying steps described above means adjusting the content of each alloying element contained in the molten alloy to a desired range. Accordingly, in the case of preparing an Al melt using pure Al in the Al melt preparation step, the content of the alloying element may be adjusted by adding the desired amount of each alloying element in each alloying step. On the other hand, in the case of preparing an Al melt using Al scrap in the Al melt preparation step, since the Al melt already contains other alloying elements as impurities, the content of the corresponding alloying element is measured in each alloying step before the addition of each alloying element. Then, the content of each alloying element can be adjusted by adding the corresponding alloying element as much as the difference from the desired content.

When the tertiary alloy melt is prepared in this way, the aluminum alloy casting is manufactured by injecting the tertiary alloy melt into the mold. (Casting step)

Meanwhile, in the casting step, the tertiary alloy melt is injected into the die casting mold while the tertiary alloy melt is maintained at 680 ~ 750 °C in order to secure smooth castability.

Of course, the casting step is a step of casting the final product by injecting it into a die casting mold, but is not limited to the step of casting the final product, and may be a step of casting an ingot or an intermediate product prepared to produce the final product.

The present invention adjusts the addition timing of Mg, adjusts the temperature and holding time in the alloying step, and adjusts the addition and timing of Be to prevent oxidation of Mg components as much as possible.

Hereinafter, the present invention will be described using Examples and Comparative Examples.

Compositions of various Examples and Comparative Examples of the present invention are as described in Table 1 below, and the specimens according to Examples and Comparative Examples are tertiary alloy melts prepared according to the above-described method for manufacturing aluminum alloy castings from 680 to An ASTM SUBSIZE test piece was prepared by injecting it into an ASTM SUBSIZE plate mold at 75 MPa while heated to 750°C.

division Al Si Mg Fe Mn Be Cu Zn Ni Sn Pb Ti Si/Mg Example 1 balance 8.5 3.6 0.3 0.1 - - - - - - - 2.4 Example 2 balance 9.0 4.5 0.5 0.3 0.005 - - - - - - 2.0 Example 3 balance 9.5 5.5 0.6 0.5 0.007 - - - - - - 1.7 Comparative Example 1 balance 7.5 2.5 0.5 0.1 - - - - - - - 3.0 Comparative Example 2 balance 12 0.2 0.8 0.1 - 3.0 0.7 0.3 0.1 0.1 0.1 60.0

In this case, Comparative Example 1 satisfies the alloy content range of (Patent Document 1) previously applied by the present applicant, and Comparative Example 2 is an aluminum alloy for conventional die casting, which is ALDC12, which is one of commercial Al-Si alloys.

In addition, thermal conductivity, electrical conductivity, tensile strength, yield strength and elongation were evaluated for the produced specimen, and the results are shown in Table 2 below.

At this time, thermal conductivity and electrical conductivity were measured after processing the prepared specimen into a 10mm*10mm*2t size specimen. At this time, the thermal conductivity was measured according to the thermal conductivity measurement test (ASTM E 1461).

In addition, tensile strength and yield strength were measured according to the tensile test (KS B 0802).

Then, a salt spray test was performed, and the results are shown in FIGS. 1 and 2 .

The salt spray test was performed according to the salt spray test (KS D 9502) using the prepared ASTM SUBSIZE die-casting tensile specimen and then using 5% NaCl salt water.

division thermal conductivity
(W/m K) electrical conductivity
(%IACS) The tensile strength
(MPa) yield strength
(MPa) elongation
(%) Example 1 150 33 347 260 3.0 Example 2 144 32 332 277 2.6 Example 3 140 30 323 291 2.0 Comparative Example 1 140 30 320 260 4.0 Comparative Example 2 96 27 300 150 3.0

As can be seen from Table 2, according to the embodiment of the present invention, the thermal conductivity is 135 W/m · K or more, the electrical conductivity is 30% IACS or more, the tensile strength is 320 MPa or more, the yield strength is 260 MPa or more, and the elongation It is possible to manufacture an aluminum alloy casting excellent in physical properties with 2.0 to 3.0% silver.

In particular, compared with Comparative Example 2, which is a conventional aluminum alloy for die casting, the yield strength is improved by about 70% or more, the thermal conductivity is improved by more than 40%, and the elongation can be secured at the same or higher level, so the durability is higher than that of the prior art. It can be seen that excellent castings can be produced. Therefore, the aluminum alloy for die casting according to an embodiment of the present invention can be used for automotive electronic parts and portable electronic devices.

In addition, Figure 1 is a photograph comparing Example 3 and Comparative Example 2 according to the present invention 24 hours and 48 hours after spraying brine (NaCl 5%), Figure 2 is Example 1 and 2 and Comparative Examples 1 and 2 are sprayed with brine (NaCl 5%), and are photographs comparing the initial, first, and second days.

As can be seen from FIG. 1 , in Comparative Example 2 (ALDC12), which is one of the commercial Al-Si alloys, corrosion was severely progressed from the time point 24 hours elapsed after salt spray, whereas Example 3 according to the present invention had 48 It can be seen that even with the lapse of time, the initial state is maintained in which corrosion hardly occurs.

In addition, similarly in FIG. 2, partial corrosion proceeds from the first day in Comparative Example 1, and full corrosion proceeds from the first day in Comparative Example 2, whereas in Examples 1 and 2 according to the present invention, corrosion occurs almost even on the second day. It can be seen that the initial state is maintained.

Next, an experiment was conducted to determine whether _{the Mg 2} Si microstructure was generated according to the change in the Mg content.

3 is a photograph showing a microstructure according to a comparative example and an embodiment of the present invention.

Prepare an aluminum alloy containing Al and other unavoidable impurities in weight %, Si: 8.5%, Fe: 0.5%, Mn: 0.1%, remaining Al and other unavoidable impurities to check whether _{Mg 2} Si microstructure is generated according to the change in the Mg content However, at this time, an aluminum alloy in which the Mg content was changed to 1.5%, 3.0%, and 4.5%, respectively, was prepared, and then the microstructure of the specimen prepared according to the aluminum alloy manufacturing method of the present invention using the aluminum alloy was observed.

As can be seen from FIG. 3 , the Mg ₂ Si microstructure, which is a corrosion resistance strengthening factor, was not observed in the specimen containing 1.5% Mg. _{And Mg 2} Si microstructure started to be generated in the specimen containing 3.0% Mg _{, and it was confirmed that the Mg 2} Si microstructure was generated in a significant amount in the specimen containing 4.5% Mg.

Next, an experiment was conducted to confirm the effect of improving the corrosion resistance according to the change in the Mg content.

4 is a photograph showing the microstructure of a specimen according to a comparative example and an embodiment of the present invention.

In order to confirm the effect of improving corrosion resistance according to the change in the Mg content, prepare an aluminum alloy containing Si: 8.5%, Fe: 0.5%, Mn: 0.1%, the remaining Al and other unavoidable impurities, in which case the Mg content was set to 3.0 % and 4.5% were prepared, and a salt spray test was performed on a specimen prepared according to the aluminum alloy manufacturing method of the present invention using the aluminum alloy, and the results are shown in FIG. 4 .

The salt spray test was performed according to the salt spray test (KS D 9502) using the prepared ASTM SUBSIZE die-casting tensile specimen and then using 5% NaCl salt water. At this time, it was observed by dividing the time into 0hr, 48hr, and 96hr.

As can be seen in Figure 4, the corrosion resistance was observed to be relatively good in the case of the specimen having a Mg content of 3.0%, but as can be seen in the specimens of 48 hr and 96 hr compared to the specimen of 0 hr, corrosion on the surface of the specimen over time I could see that this happened little by little.

On the other hand, in the case of a specimen having a Mg content of 4.5%, it was observed that the corrosion resistance was very good. In particular, as can be seen in the specimens of 48 hr and 96 hr even compared to the specimen of 0 hr, it was confirmed that corrosion did not occur on the surface of the specimen even with the passage of time.

These results can be inferred that there is a significant difference in corrosion resistance depending on the amount of _{Mg 2 Si microstructure.}

Although the present invention has been described with reference to the accompanying drawings and the above-described preferred embodiments, the present invention is not limited thereto, and is defined by the following claims. Accordingly, those of ordinary skill in the art can variously change and modify the present invention within the scope without departing from the spirit of the claims to be described later.

Claims (16)

By weight%, Si: 7.8 to 10.5%, Mg: 3.6 to 5.5%, Fe: 0.3 to 1.0%, Mn: 0.1 to 1.0%, the remaining Al and other unavoidable impurities.
The method according to claim 1,
The aluminum alloy is Be: Aluminum alloy for die casting, characterized in that it further contains 0.002 to 0.02%.
The method according to claim 1,
The aluminum alloy is an aluminum alloy for tie-casting, characterized in that Si: 8.0 to 10.5%.
The method according to claim 1,
The aluminum alloy is an aluminum alloy for die casting, characterized in that the ratio of Si / Mg is 1.5 or more and less than 3.0.
The method according to claim 1,
Among the impurities contained in the aluminum alloy, Cu, Zn and Ni are aluminum alloy for die casting, characterized in that the total content is 0.2% or less.
The method according to claim 1 or 2,
The aluminum alloy is an aluminum alloy for die casting, characterized in that the yield strength is 260 MPa or more.
The method according to claim 1 or 2,
The aluminum alloy is an aluminum alloy for die casting, characterized in that the tensile strength is 320 MPa or more.
The method according to claim 1 or 2,
The aluminum alloy is an aluminum alloy for die casting, characterized in that the elongation is 2.0 to 3.0%.
The method according to claim 1 or 2,
The aluminum alloy is an aluminum alloy for die casting, characterized in that the thermal conductivity is 135 w / mK or more.
The method according to claim 1 or 2,
The aluminum alloy is an aluminum alloy for die casting, characterized in that the electrical conductivity is 30% IACS or more.
An Al melt preparation step of preparing an Al melt by dissolving Al or Al scrap;
A first temperature raising step of raising the temperature of the prepared Al melt;
a first alloying step of preparing a first alloy melt by adjusting the content of Si in the heated Al melt to 7.8 to 10.5%;
a second temperature raising step of raising the temperature of the first alloy melt;
A secondary alloying step of preparing a secondary alloy melt by adjusting the content of Fe to 0.3 to 1.0% in the heated primary alloy melt, and adjusting the content of Mn to 0.1 to 1.0%;
a temperature reduction step of reducing the temperature of the secondary alloy melt;
A method for manufacturing an aluminum alloy casting comprising a tertiary alloying step of preparing a tertiary alloy melt by adjusting the content of Mg to 3.6 to 5.5% in the reduced temperature secondary alloy melt.
12. The method of claim 11,
In the first alloying step, the aluminum alloy casting manufacturing method, characterized in that by adjusting the content of Si to 8.0 ~ 10.5% to prepare a primary alloy melt.
12. The method of claim 11,
In the secondary alloying step, Be: 0.002 to 0.02% of the heated primary alloy molten material is further added to the aluminum alloy casting manufacturing method.
12. The method of claim 11,
The first temperature raising step is to raise the temperature of the Al melt to 800 ~ 850 ℃,
The second temperature raising step raises the temperature of the primary alloy melt to 900 ~ 950 ℃,
The temperature reduction step is a method of manufacturing an aluminum alloy for die casting, characterized in that the temperature of the secondary alloy melt to 700 ~ 750 ℃.
12. The method of claim 11,
Method of manufacturing an aluminum alloy for die casting further comprising a casting step of manufacturing an aluminum alloy casting by injecting a tertiary alloy melt into a mold.
16. The method of claim 15,
The casting step is a method of manufacturing an aluminum alloy for die casting, characterized in that by injecting the tertiary alloy melt into the die casting mold at 680 ~ 750 ℃.

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