CN112981190A

CN112981190A - Aluminum alloy for die casting and method for manufacturing cast aluminum alloy using the same

Info

Publication number: CN112981190A
Application number: CN202010640385.3A
Authority: CN
Inventors: 金柄秀; 林栽善; 许昵; 李廷穆
Original assignee: Sj Tech Co ltd; Hyundai Motor Co; Kia Motors Corp
Current assignee: Sj Tech Co ltd; Hyundai Motor Co; Kia Corp
Priority date: 2019-12-16
Filing date: 2020-07-06
Publication date: 2021-06-18
Also published as: US20210180159A1; DE102020208831A1; KR20210076329A

Abstract

Disclosed are an aluminum alloy for die casting, which has excellent thermal conductivity and corrosion resistance and is useful for parts requiring heat dissipation and high corrosion resistance, and a method of manufacturing a cast aluminum alloy using the same. The present invention provides an aluminum alloy for die casting, which may include silicon (Si) in an amount of about 8.5 wt% to 10.5 wt%, magnesium (Mg) in an amount of about 3.6 wt% to 5.5 wt%, iron (Fe) in an amount of about 0.3 wt% to 1.0 wt%, manganese (Mn) in an amount of about 0.1 wt% to 1.0 wt%, and the balance aluminum (Al) and inevitable impurities, all wt% based on the total weight of the aluminum alloy.

Description

Aluminum alloy for die casting and method for manufacturing cast aluminum alloy using the same

Technical Field

The present invention relates to an aluminum alloy for die casting and a method of producing a cast aluminum alloy using the aluminum alloy for die casting. The aluminum alloy for die casting may have excellent thermal conductivity and corrosion resistance, and thus may be used for parts requiring heat dissipation and high corrosion resistance.

Background

In general, aluminum (Al) has been widely used in various industries because it is easily cast, well alloyed with other metals, has excellent corrosion resistance in ambient atmosphere, and exhibits excellent electrical and thermal conductivities.

In particular, in recent years, aluminum has been actively used for reducing the weight of a vehicle and improving fuel efficiency, however, since aluminum itself is inferior in strength to other metals, an aluminum alloy obtained by mixing aluminum with other metals is generally used.

Die casting has been widely used as a method of manufacturing products using such aluminum alloys. Die casting is a precision casting method that involves injecting molten metal into a mold having a cavity precisely machined to have a desired shape, thereby obtaining a cast product having the same shape as the cavity.

For producing molded alloy products by die casting, aluminum alloys may require properties that meet the requirements of a method that includes filling a cavity in a mold with molten metal at a high rate and high pressure, and then allowing it to solidify. For example, an aluminum alloy for die casting should have fluidity suitable for high-pressure casting and be able to compensate for shrinkage defects that may occur during solidification by providing appropriate levels of high-temperature viscosity and latent heat.

Currently, widely used aluminum alloys for die casting include Al — Si-based alloys (e.g., ADC 3, ADC 10, and ADC 12) and Al — Mg-based alloys (e.g., ADC 5 and ADC 6). However, these aluminum alloys for die casting have limitations in widening the range of applications due to their low heat dissipation and low corrosion resistance.

In the related art, aluminum alloys for die casting capable of improving thermal conductivity and corrosion resistance have been reported.

However, although the thermal conductivity and the corrosion resistance can be improved to some extent, there is a limitation in the effectiveness of improving the thermal conductivity and the corrosion resistance because the ratio of Mg content/Si content in the conventional aluminum alloy is low.

The above information disclosed in this background section is only provided to enhance understanding of the background of the invention and, therefore, may contain information that does not form the prior art that is already known in this country to a person skilled in the art.

Disclosure of Invention

In a preferred aspect, there are provided an aluminum alloy for die casting, a molded product (e.g., a part requiring heat dissipation and high corrosion resistance or a vehicle part), and a method of producing a cast aluminum alloy using the aluminum alloy for die casting, which has excellent thermal conductivity and corrosion resistance. In particular, the aluminum alloy can be obtained by controlling the contents of Si, Mg, Fe, Mn, and Al contained.

In one aspect, there is provided an aluminum alloy for die casting that can maintain excellent castability and formability while maintaining excellent thermal conductivity and corrosion resistance by controlling contents of Si and Mg and a ratio thereof. In another aspect, a method of producing a cast aluminum alloy using the aluminum alloy for die casting is provided.

The aluminum alloy for die casting may include silicon (Si) in an amount of about 7.8 wt% to 10.5 wt%, magnesium (Mg) in an amount of about 3.6 wt% to 5.5 wt%, iron (Fe) in an amount of about 0.3 wt% to 1.0 wt%, manganese (Mn) in an amount of about 0.1 wt% to 1.0 wt%, and the balance aluminum (Al) and other unavoidable impurities. All wt% are based on the total weight of the aluminum alloy.

The aluminum alloy may also include beryllium (Be) in an amount of about 0.002 wt% to 0.02 wt%.

Preferably, the aluminum alloy may include silicon (Si) in an amount of about 8.0 wt% to 10.5 wt%.

The ratio of Si/Mg may be not less than about 1.5 and less than about 3.0.

The total content of copper (Cu), zinc (Zn), and nickel (Ni) contained as impurities in the aluminum alloy may be an amount of about 0.2 wt% or less.

The aluminum alloy may have a yield strength of about 260MPa or greater.

The aluminum alloy may have a tensile strength of about 320MPa or greater.

The elongation of the aluminum alloy may be about 2.0% to 3.0%.

The thermal conductivity of the aluminum alloy can be about 135 w/m-K or higher.

The aluminum alloy can have an electrical conductivity of about 30% IACS or greater.

A method of producing a cast aluminum alloy is also provided. The method may include: preparing a molten aluminum (Al) batch by melting aluminum (Al) or Al scrap; heating the prepared molten Al batch; preparing a primary molten alloy by adjusting a silicon (Si) content in the heated molten Al to about 7.8 wt% to 10.5 wt% for primary alloying; secondarily heating and primarily melting the alloy; preparing a secondary molten alloy by adjusting an iron (Fe) content in the heated primary molten alloy to about 0.3 wt% to 1.0 wt% and adjusting a manganese (Mn) content to about 0.1 wt% to 1.0 wt% to perform secondary alloying; cooling the secondary molten alloy; and preparing a tertiary molten alloy by adjusting a magnesium (Mg) content in the cooled secondary molten alloy to about 3.6 wt% to 5.5 wt% to perform tertiary alloying. All wt% are based on the total weight of the cast aluminum alloy.

The primary alloying may include adjusting the Si content to about 8.0 wt% to 10.5 wt% to prepare a primary molten alloy.

The secondary alloying may also include adding beryllium (Be) to the heated primary molten alloy in an amount of about 0.002 wt% to 0.02 wt%.

The primary heating may include heating the molten Al ingot to a first temperature of about 800 ℃ to 850 ℃.

The secondary heating may include heating the primary molten alloy to a second temperature of about 900 ℃ to 950 ℃.

The cooling may include cooling the second molten alloy to a third temperature of about 700 ℃ to 750 ℃.

The method may further include casting the three molten alloys injected into the mold to produce a cast aluminum alloy.

Casting may include injecting three times of the molten alloy into a mold for die casting at a casting temperature of about 680 ℃ to 750 ℃.

Also provided are molded products, e.g., vehicle parts, comprising the aluminum alloys described herein. For example, the molded parts can be made by the methods described herein using aluminum alloys.

Other aspects of the invention are disclosed below.

Drawings

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description presented in conjunction with the accompanying drawings, in which:

FIG. 1 shows an image comparing the results of a salt spray test between comparative example 2 and example 3 according to an exemplary embodiment of the present invention;

FIG. 2 shows images comparing the results of salt spray tests between comparative example 1 and examples 1-2 according to an exemplary embodiment of the present invention;

FIG. 3 is an image showing microstructures of comparative example and example according to an exemplary embodiment of the present invention; and

fig. 4 is an image showing the microstructures of samples of comparative example and example according to an exemplary embodiment of the present invention.

Detailed Description

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. However, the present invention is not limited to the embodiments, and may be implemented in various forms. These embodiments are provided only to fully illustrate the present invention and to fully inform the scope of the present invention to those skilled in the art.

The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Unless specifically stated or otherwise apparent from the context, the term "about" as used herein is understood to be within the normal tolerance of the art, e.g., within 2 standard deviations of the mean. "about" can be understood as a deviation within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05% or 0.01% of the stated value. All numerical values provided herein are modified by the term "about" unless otherwise clear from the context.

In one aspect, an aluminum alloy for die casting may include silicon (Si) in an amount of about 7.8 wt% to 10.5 wt%, magnesium (Mg) in an amount of about 3.6 wt% to 5.5 wt%, iron (Fe) in an amount of about 0.3 wt% to 1.0 wt%, manganese (Mn) in an amount of about 0.1 wt% to 1.0 wt%, and the balance aluminum (Al) and inevitable impurities. All wt% are based on the total weight of the aluminum alloy. In addition, the aluminum alloy may also include beryllium (Be) in an amount of about 0.002 wt% to 0.02 wt%.

Further, the aluminum alloy for die casting may optionally not contain copper (Cu), zinc (Zn), and nickel (Ni). However, the aluminum alloy may contain copper (Cu), zinc (Zn), and nickel (Ni) as inevitable impurities. However, even when copper (Cu), zinc (Zn), and nickel (Ni) are contained as impurities, it is preferable to adjust the total content thereof to about 0.2 wt% or less.

Next, the reason for limiting the alloy composition and the composition range thereof will be described. All wt% are based on the total weight of the aluminum alloy (or composition thereof).

Silicon (Si) in an amount of about 7.8 wt% to 10.5 wt%

Silicon (Si) is a major element that can improve castability and wear resistance and affect thermal conductivity and strength.

When silicon (Si) is added in an amount of less than about 7.8 wt%, the effect of improving castability, wear resistance and strength is not satisfactory, and when silicon (Si) is added in an amount of more than about 10.5 wt%, the workability (e.g., machinability) of the obtained cast product may be reduced, and the heat treatment may be ineffective. Therefore, the silicon (Si) content is limited to this range.

In particular, silicon (Si) is an essential element for ensuring fluidity and formability of molten metal during the die casting process. As the content of magnesium (Mg) increases, corrosion resistance may be improved, and as the content of magnesium (Mg) increases, formability and fluidity significantly decrease. To compensate for these problems, the temperature of the molten metal may be increased during the die casting process to obtain a product. However, when the temperature of the molten metal is increased, productivity may be decreased and a defect rate may be increased. For example, the product may suffer from thermal cracking and may reduce the useful life of the molding die.

To control this problem in the alloy, the Si content may be increased. The Si content may be adjusted to about 7.8 wt% to 10.5 wt% to ensure corrosion resistance, castability, and productivity. Preferably, the Si content may be about 8.0 wt% to 10.5 wt%, or specifically about 8.5 wt% to about 10.5 wt%.

Magnesium (Mg) in an amount of about 3.6 wt% to 5.5 wt%

Magnesium (Mg) is a main element that can improve not only corrosion resistance but also strength, elongation, and cast workability, and forms Mg when it reacts with silicon (Si)₂In the Si crystalline phase, Mg₂The Si crystalline phase will become the sacrificial etch site.

When magnesium (Mg) is present in an amount less than about 3.6 wt%, the effect of improving corrosion resistance, strength, and elongation may be insufficient. When magnesium (Mg) is present in an amount greater than about 5.5 wt%, castability may be reduced due to a reduction in fluidity of the molten metal during casting, and dross may be increased due to an increase in oxidation tendency of the molten metal. Therefore, the magnesium (Mg) content is limited to this range.

Iron (Fe) in an amount of about 0.3 wt% to 1.0 wt%

Iron (Fe) is an element that helps prevent mold sand-out and product scratching.

In this case, when iron (Fe) is present in an amount of less than 0.3%, the effect of improving strength is insufficient, and when iron (Fe) is present in an amount of more than 1%, wear resistance and thermal conductivity may be reduced. Therefore, the iron (Fe) content is limited to this range.

Manganese (Mn) in an amount of about 0.1 wt% to 1.0 wt%

Manganese (Mn) is an element that can contribute to strengthening of solid solution together with iron (Fe), thereby improving high-temperature strength of castings, preventing mold sand sticking, and improving solubility.

When manganese (Mn) is present in an amount of less than about 0.1 wt%, the effect of improving strength may be insufficient, and when manganese (Mn) is present in an amount of more than about 1.0 wt%, castability and machinability may be reduced, and thermal conductivity may be reduced. Therefore, the manganese (Mn) content is limited to this range.

Beryllium (Be) in an amount of about 0.002 to 0.02 wt%

Beryllium (Be) is an element that prevents oxidation of magnesium (Mg), suppresses dross formed during casting, and improves corrosion resistance.

When beryllium (Be) is present in an amount of less than about 0.002 wt%, the effect of improving corrosion resistance may Be insufficient, and when beryllium (Be) is present in an amount of more than about 0.02 wt%, corrosion resistance may Be reduced. Therefore, the beryllium (Be) content is limited to this range.

Meanwhile, the balance is composed of aluminum (Al) and other inevitable impurities in addition to the above components.

For example, to ensure that the corrosion resistance of the aluminum alloy reaches a desired level, the aluminum alloy preferably optionally does not contain copper (Cu), zinc (Zn), or nickel (Ni) (elements that cause corrosion). However, even when copper (Cu), zinc (Zn), and/or nickel (Ni) is inevitably contained, it is preferable to adjust the total content thereof to about 0.2 wt% or less.

Further, in order to appropriately generate Mg₂Si (a factor enhancing corrosion resistance), the Si/Mg ratio may be limited to not less than about 1.5 and less than about 3.0.

Further, the content of Si may be adjusted to prevent a decrease in castability, a decrease in productivity due to an increase in the incidence of hot cracking, and an increase in defect rate (all of which are caused by an increase in the content of Mg) as compared to an improvement in wear resistance and strength. The increase in thermal conductivity can be predicted by optimizing the two components.

When the Si/Mg ratio is less than about 1.5, the Si content may be relatively less than the Mg content, which may cause problems of reduced castability and occurrence of hot cracks during casting. Further, when the Si/Mg ratio is greater than about 3.0, the relative Si content may increase and the Mg content may decrease, which may cause a problem in that the improvement of corrosion resistance and strength does not reach a desired level.

In one aspect, a method of producing a cast aluminum alloy is provided. The cast aluminum alloy can include the composition of the aluminum alloys described herein.

First, aluminum (Al) or Al scrap may be melted at a temperature of about 750 ℃ to produce molten Al (to produce molten Al). In order to minimize the content of impurities contained in the Al scrap, it is preferable to use a high-quality Al scrap. For example, in order to reduce the Cu (corrosion resistance reducing element) content to about 0.15 wt%, it is preferable to use only forged aluminum high-quality aluminum scrap as the Al scrap. Therefore, preferably, 1000-, 6000-and 7000-based Al scrap should not be used.

When the molten Al is prepared by sufficiently melting Al or Al scrap, the prepared molten Al may be heated to a first temperature (primary heating) of about 800 to 850 ℃.

When the molten Al is heated to the first temperature of 800 to 850 ℃, the content of Si in the molten Al may be adjusted to about 8.5 to 10.5 wt% to prepare a primary molten alloy (primary alloying) in which Si is sufficiently melted.

When the primary molten alloy having a controlled Si content in Al is prepared as described above, the primary molten alloy may be heated to a second temperature (secondary heating) of about 900 to 950 ℃.

Then, the content of Fe in the heated primary molten alloy may be adjusted to about 0.3 wt% to 1.0 wt%, and the content of Mn may be adjusted to about 0.1 wt% to 1.0 wt% to prepare a secondary molten alloy (secondary alloying).

The content of Be in the heated primary molten alloy may Be adjusted to about 0.002 wt% to 0.02 wt%.

The elevated temperature may Be sufficiently maintained for about 5 hours in order to sufficiently melt Fe, Mn and Be in the primary molten alloy.

Thus, when preparing the second molten alloy, the second molten alloy may be cooled to a third temperature (cool) of about 700 ℃ to 750 ℃.

Then, the content of Mg in the cooled secondary molten alloy may be adjusted to about 3.6 wt% to 5.5 wt% to prepare a tertiary molten alloy (tertiary alloying).

Meanwhile, temperature ranges in the primary heating, the secondary heating, and the cooling may be designed to control aluminum oxide (Al) and magnesium oxide (Mg), which may be generated unnecessarily outside the temperature range suggested in each step, which may hinder uniform alloying, and thus desired physical properties may not be achieved in the present invention.

For example, when the temperature maintained during cooling is less than the suggested third temperature, magnesium carbonate may be generated during three alloying processes, resulting in an aluminum alloy having an undesirable yellow color. Further, when the temperature maintained in cooling is greater than the suggested third temperature, magnesium oxide may be generated during the three-time alloying, resulting in an aluminum alloy having an undesirable blue color.

At this time, cooling may be slowly performed while maintaining the temperature of the triple-melted alloy at a temperature of about 700 to 750 ℃ for about 1 hour. Therefore, dross and oxides generated in the third molten alloy can be removed.

In the above-described primary alloying to tertiary alloying, adjusting the content of each alloying element may include adjusting the content of each alloying element contained in the molten alloy to a desired range. Therefore, in the case of producing molten Al using pure Al in the production of molten Al, the content of each alloying element in each alloying step can be adjusted by adding an element to the content to be adjusted. On the other hand, in the case of producing molten Al using Al scrap in the production of molten Al, other alloying elements may already be contained as impurities in the molten Al before each alloying element is added in the process of each alloying. In this way, the content of each alloying element can be adjusted by measuring the content of the corresponding element and then adding the corresponding element in an amount corresponding to the difference from the content to be adjusted.

When preparing the third molten alloy, the third molten alloy may be injected into a mold to produce a cast aluminum alloy product (casting).

Casting may be performed by injecting the three-time molten alloy into a mold for die casting while maintaining the three-time molten alloy at a casting temperature of about 680 to 750 ℃ to ensure smooth casting.

The casting may be a step of casting a final product by injection into a mold for die casting, but the casting is not limited to a step of casting a final product, and may be a step of casting an ingot or an intermediate product prepared for producing a final product.

According to the present invention, the oxidation of the Mg component can Be prevented as much as possible by adjusting the timing of Mg addition, adjusting the temperature and retention time during alloying, and adjusting the addition and timing of Be addition.

Examples

Hereinafter, the present invention is described with reference to examples and comparative examples.

Table 1 below shows various compositions of examples and comparative examples according to exemplary embodiments of the present invention, and the samples according to the examples and comparative examples were produced as ASTM sub-size samples by heating three times of molten alloy prepared according to the above-described method of producing a cast aluminum alloy to a temperature of 680 ℃ to 750 ℃ and injecting it into an ASTM sub-size plate mold of 75 MPa.

TABLE 1

Comparative example 1 is an alloy composition of the related art, and comparative example 2 is ALDC12, which is a conventional general-purpose aluminum alloy for die casting, and is a commercially available Al — Si-based alloy.

In addition, the produced samples were tested to measure thermal conductivity, electrical conductivity, tensile strength, yield strength and elongation, and the results are shown in table 2 below.

After processing the prepared samples into samples having dimensions of 10mm x 2t, the thermal and electrical conductivity was measured. At this time, the thermal conductivity was measured according to the thermal conductivity measurement test (ASTM E1461).

Further, the tensile strength and yield strength were measured according to the tensile test (KS B0802).

In addition, a salt spray test was performed, and the results are shown in fig. 1 and 2.

After preparing the prepared ASTM sub-size die cast tensile specimen, a salt spray test was performed according to the salt spray test (KS D9502) using 5% NaCl as salt water.

TABLE 2

As shown in table 2, the exemplary cast aluminum alloys have excellent physical properties, for example, thermal conductivity of 135W/m · K or more, electrical conductivity of 30% IACS or more, tensile strength of 320MPa or more, yield strength of 260MPa or more, and elongation of 2.0% to 3.0% or more.

In particular, when compared with comparative example 2(a conventional general aluminum alloy for die casting), the yield strength of the exemplary aluminum alloy is improved by about 70% or more, the thermal conductivity is improved by 40% or more, and the elongation can be secured at the same level or more. Accordingly, the cast product in the exemplary embodiment of the present invention having significantly improved properties compared to those of the conventional cast product is produced. Therefore, the aluminum alloy for die casting according to the exemplary embodiment of the present invention may be used for electronic parts of vehicles and portable electronic devices.

Further, fig. 1 is an image comparing example 3 and comparative example 2 according to an exemplary embodiment of the present invention at 24 hours and 48 hours after the brine (NaCl 5%) spraying, and fig. 2 is an image comparing example 3 and comparative example 2 according to an exemplary embodiment of the present invention at an initial stage in the first day and the second day after the brine spraying (NaCl 5%).

As shown in fig. 1, in comparative example 2(ALDC12, one of commercial Al — Si-based alloys), severe corrosion occurred 24 hours after the brine spray, while example 3 according to the present invention was able to maintain an initial state in which corrosion hardly occurred (even after 48 hours).

Further, as shown in fig. 2, comparative example 1 shows partial corrosion from the first day, and comparative example 2 shows corrosion in the entire area from the first day, whereas example 1 and example 2 according to the exemplary embodiment of the present invention can maintain an initial state in which corrosion hardly occurs (even on the second day).

To determine whether Mg was formed as a function of Mg content₂Si microstructure, also tested.

Fig. 3 is an image showing microstructures of comparative example and example according to the present invention.

To determine Mg as a function of Mg content₂Formation of the Si microstructure an aluminium alloy was prepared comprising Si in an amount of 8.5 wt%, Fe in an amount of 0.5 wt%, Mn in an amount of 0.1 wt% and the balance Al and other unavoidable impurities, wt% based on the total weight of the aluminium alloy. Aluminum alloys were prepared by changing the Mg content to 1.5 wt%, 3.0 wt%, and 4.5 wt%, respectively, and then observing the use of the aluminum alloys according to an exemplary method of producing the aluminum alloysMicrostructure of gold prepared samples.

As shown in FIG. 3, no Mg was observed in the sample containing 1.5 wt% Mg₂The microstructure of Si (which is a factor of improving corrosion resistance). Further, Mg began to be produced in the sample containing 3.0 wt% of Mg₂Si microstructure and a large amount of Mg was produced in the sample containing 4.5 wt% Mg₂A Si microstructure.

To determine the effect of improving corrosion resistance as a function of Mg content, additional experiments were conducted.

Fig. 4 is an image showing the microstructures of the comparative example and the sample according to the embodiment of the present invention.

In order to determine the effect of improving corrosion resistance as a function of Mg content, an aluminum alloy containing Si in an amount of 8.5 wt%, Fe in an amount of 0.5 wt%, Mn in an amount of 0.1 wt%, and Al and inevitable impurities as the balance was prepared, and a salt spray test was performed on samples prepared using the aluminum alloy according to an exemplary method of producing the aluminum alloy while changing the Mg content to 3.0 wt% and 4.5 wt%, respectively, and the results are shown in fig. 4.

After obtaining the prepared ASTM sub-size die cast tensile specimen, a brine spray test was performed according to the brine spray test (KS D9502) using 5% NaCl as brine. At this time, observation was performed at 0 hour, 48 hours, and 96 hours, respectively.

As shown in fig. 4, the samples having a Mg content of 3.0 wt% have relatively good corrosion resistance, but, as can be seen from fig. 4, the surfaces of the samples at 48 hours and 96 hours were gradually corroded with time, as compared to the samples at 0 hours.

On the other hand, the sample having a Mg content of 4.5 wt% had very excellent corrosion resistance. In particular, when compared with the 0 hour sample, no corrosion occurred on the sample surface of the samples of 48 hours and 96 hours even after the lapse of time.

These results confirm that Mg dependence₂There is a significant difference in the amount of Si microstructure, corrosion resistance.

The exemplary embodiment of the present invention has the effect of ensuring excellent thermal conductivity and corrosion resistance as compared to conventional aluminum alloys for die casting, thereby enabling production of various cast products for manufacturing vehicle electronic parts and portable electronic devices, which require heat dissipation and high corrosion resistance.

Further, the exemplary embodiments of the present invention can produce a cast product having superior strength and elongation compared to a conventional aluminum alloy for die casting.

Although various exemplary embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and deletions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. An aluminum alloy for die casting, comprising:

silicon in an amount of 7.8 wt% to 10.5 wt%;

magnesium in an amount of 3.6 to 5.5 wt%;

iron in an amount of 0.3 to 1.0 wt%;

manganese in an amount of 0.1 to 1.0 wt%; and

the balance of aluminum and other unavoidable impurities,

all wt% are based on the total weight of the aluminum alloy.

2. The aluminum alloy for die casting according to claim 1, further comprising beryllium in an amount of 0.002 wt% to 0.02 wt%.

3. The aluminum alloy for die casting according to claim 1, wherein the aluminum alloy includes silicon in an amount of 8.0 wt% to 10.5 wt%.

4. The aluminum alloy for die casting according to claim 1, wherein a Si/Mg ratio is not less than 1.5 and less than 3.0.

5. The aluminum alloy for die casting according to claim 1, wherein the total content of copper, zinc, and nickel contained as impurities in the aluminum alloy is 0.2 wt% or less.

6. An aluminum alloy for die casting according to claim 1, wherein the aluminum alloy has a yield strength of 260MPa or more.

7. An aluminum alloy for die casting according to claim 1, wherein the aluminum alloy has a tensile strength of 320MPa or more.

8. The aluminum alloy for die casting according to claim 1, wherein the elongation of the aluminum alloy is 2.0 to 3.0%.

9. An aluminum alloy for die casting according to claim 1, wherein the aluminum alloy has a thermal conductivity of 135 w/m-K or more.

10. An aluminium alloy for die casting according to claim 1, wherein the aluminium alloy has an electrical conductivity of 30% IACS or higher.

11. A method of producing a cast aluminum alloy, the method comprising:

preparing a molten aluminum batch by melting aluminum or Al scrap to produce molten Al;

first heating the prepared molten Al batch;

preparing a primary molten alloy by adjusting a content of Si in the heated molten Al batch to 7.8 wt% to 10.5 wt% for primary alloying;

secondarily heating and primarily melting the alloy;

preparing a secondary molten alloy by adjusting the content of iron in the heated primary molten alloy to 0.3 wt% to 1.0 wt% and adjusting the content of manganese to 0.1 wt% to 1.0 wt% to perform secondary alloying;

cooling the secondary molten alloy; and

preparing a tertiary molten alloy by adjusting the content of magnesium in the cooled secondary molten alloy to 3.6 to 5.5 wt% to perform tertiary alloying,

all wt% are based on the total weight of the cast aluminum alloy.

12. The method of producing a cast aluminum alloy of claim 11, wherein the primary alloying includes adjusting the content of Si to 8.0 wt% to 10.5 wt% to prepare a primary molten alloy.

13. The method of producing a cast aluminum alloy of claim 11, wherein the secondary alloying further comprises adding beryllium to the heated primary molten alloy in an amount of 0.002 wt% to 0.02 wt%.

14. The method of producing a cast aluminum alloy of claim 11, wherein the primary heating includes heating the molten Al batch to a first heating temperature of 800 ℃ to 850 ℃,

the secondary heating includes heating the primary molten alloy to a second temperature of 900 ℃ to 950 ℃, and

the cooling includes cooling the secondary molten alloy to a third temperature of 700 ℃ to 750 ℃.

15. The method of producing a cast aluminum alloy according to claim 11, further comprising a casting step of injecting the molten alloy three times into a mold to produce a cast aluminum alloy.

16. The method of producing a cast aluminum alloy of claim 15, wherein the casting step includes injecting the three times molten alloy into a mold for die casting at a casting temperature of 680 ℃ to 750 ℃.

17. A vehicle component comprising the aluminum alloy for die casting of claim 1.