WO2014109624A1

WO2014109624A1 - Aluminum alloy for die casting and preparation method therefor

Info

Publication number: WO2014109624A1
Application number: PCT/KR2014/000409
Authority: WO
Inventors: 박태광; 정상수; 정윤철
Original assignee: 주식회사 케이에이치바텍
Priority date: 2013-01-14
Filing date: 2014-01-14
Publication date: 2014-07-17
Also published as: KR20140091858A

Abstract

An aluminum alloy for die casting according to the present invention comprises 8.5-10.5 wt% of silicon (Si), 2.0-3.7 wt% of copper (Cu), 1.0 wt% or less of iron (Fe), 1.0-5.0 wt% of zinc (Zn), 0.6-1.0 wt% of magnesium (Mg), 0.4 wt% or less of manganese (Mn), and the balance of aluminum (Al) and other inevitable impurities.

Description

Die casting aluminum alloy and its manufacturing method

The present invention relates to an aluminum alloy for die casting and a method of manufacturing the same, wherein silicon (Si), copper (Cu), iron (Fe), zinc (Zn), magnesium (Mg) and manganese (Mn) The present invention relates to a die-casting aluminum alloy and a method of manufacturing the same, in which strength and elongation are added, and nickel (Ni), which is a noxious element, is not added to have affinity and fine grain size to maximize the surface treatment effect.

Recently, with the rapid development of IT technology, the demand for slimming and large screen of electronic products, especially mobile phones is increasing, and accordingly, the need for high strength materials is emerging.

Aluminum is a silver-white soft metal, which is made of thin foil or wire because of its malleability and ductility, and its properties vary depending on the purity. It is an electrically conductive material and is a typical light metal in terms of specific gravity. It is often used as a material for wires.

In addition, aluminum is used as a major material for aircraft, ships and vehicles because of its light and durable characteristics, and easily reacts with oxygen, but after the oxide film is formed, the film is blocked from contact with oxygen, so it does not rust well and is polished. This is often used for parts that need to last long.

The aluminum material may be formed by applying plastic processing such as forging / extrusion / rolling to increase strength through aging heat treatment.

However, in the case of electronic products, it is necessary to maintain precise dimensions, and when such plastic processing is applied, an additional machining process is required, resulting in a problem of cost increase. Therefore, the die casting process is suitable for electronic products which require precise dimensions and are mainly for mass production.

For example, ALDC12 and AZ91D, which are used for exterior parts of electronic components, are used in the die casting process.

1 is a table describing the content of each component of the ALDC12 and AZ91D.

However, ALDC12 alloy has a low yield strength of 165 MPa and a tensile strength of 331 MPa, while AZ91D alloy has a lower yield strength of 150 MPa and tensile strength of 230 MPa. have.

In order to solve this problem, ZA27 alloy was developed.

The ZA27 alloy has a yield strength of 365 MPa and a yield strength of 426 MPa, which is satisfactory in terms of strength, but has a specific gravity of 5 g / cc, which is nearly twice the weight of a general aluminum alloy, and thus has a problem against the hardening trend.

Korean Patent Laid-Open Publication No. 10-2010-0041532 discloses a high-strength aluminum alloy for die casting in which the strength is enhanced while maintaining the specific gravity of aluminum.

The disclosed patent comprises 5 to 9% zinc, 1 to 2% copper, 0.05 to 0.2% titanium, and aluminum balance.

However, since the aging treatment is performed at 120 ° C. for 24 hours or longer to have a tensile strength of 350 MPa or more, productivity is lowered and manufacturing costs are rapidly increased.

Korean Patent Publication No. 2012-0020406 discloses 0.35 to 0.5 wt% of silicon (Si), 0.55 to 0.9 wt% of magnesium (Mg), and copper in order to provide a good castability of aluminum and zinc alloys while maintaining high strength without heat treatment. (Cu) 2.0 to 2.1 wt%, zinc (Zn) 19.5 to 40.5 wt%, iron (Fe) 0.6 wt% max, manganese (Mn) 0.2 wt% max, nickel (Ni) 0.05 wt% max, titanium (Ti) An alloy consisting of 0.03 to 0.05 wt%, other impurities 0.05 wt% max and balance aluminum is disclosed.

However, in recent years, regulations on the eco-friendliness and human harmfulness of electronic materials applied are increasing, and the use of harmful elements such as nickel, lead, beryllium, and cobalt is banned.

In the case of the aluminum alloy disclosed in Korean Patent Laid-Open Publication No. 10-2007-0091669, although the strength is improved, it is far from environmentally friendly materials because it contains 1.5 wt.% Or less of nickel (Ni), which is a hazardous substance.

An object of the present invention is to solve the conventional problems as described above, and more specifically, to aluminum (Al), silicon (Si), copper (Cu), iron (Fe), zinc (Zn), magnesium (Mg) ), To increase the strength and elongation by adding manganese (Mn), to the aluminum alloy for die-casting and a method of manufacturing the same to add a harmful element nickel (Ni) to have affinity and to maximize the surface treatment effect. have.

Another object of the present invention is to provide an environmentally friendly die-cast aluminum alloy and its manufacturing method so that no harmful elements are included.

Die-casting aluminum alloy according to the present invention for achieving the above object, by weight% 8.5 to 10.5% silicon (Si), 2.0 to 3.7% copper (Cu), 1.0% or less iron (Fe) And 1.0-5.0% zinc (Zn), 0.6-1.0% magnesium (Mg), 0.4% or less manganese (Mn), balance aluminum (Al) and other unavoidable impurities It is characterized by.

It is characterized by having an average cast lip size of 4.7 ㎛ or less.

It has a tensile strength of 266 ~ 363 MPa.

It has a yield strength of 243 to 266 MPa.

It is characterized by having a break elongation of 0.6 ~ 2.2%.

Magnesium (Mg) is characterized in that it is added using a magnesium (Mg) -calcium (Ca) master alloy.

The method for producing a die-cast aluminum alloy according to the present invention includes a melting step of dissolving aluminum and an aluminum master alloy in a melting furnace, and adding a magnesium-calcium mother alloy to the melting furnace by weight to 8.5 to 10.5% of silicon (Si) and , 2.0-3.7% copper (Cu), 1.0% or less iron (Fe), 1.0-5.0% zinc (Zn), 0.6-1.0% magnesium (Mg), 0.4% or less manganese ( And a completion step of completing a die casting aluminum alloy including Mn) and the remaining aluminum (Al) and other unavoidable impurities.

The die casting aluminum alloy is characterized in that it has a re-dissolution temperature of 700 ~ 750 ℃.

In the present invention, silicon (Si), copper (Cu), iron (Fe), zinc (Zn), magnesium (Mg), manganese (Mn) were added to aluminum (Al), and nickel (Ni) was not included.

Therefore, there is an advantage that the strength and elongation is improved and environmentally friendly due to no addition of harmful elements.

In addition, the formability is improved to a fine grain size has the advantage of maximizing the surface treatment effect, such as painting and plating.

1 is a table showing the content of each component of the aluminum alloy according to the prior art.

Figure 2 is a real photograph of a product produced by die casting aluminum alloy for die casting according to the present invention.

Figure 3 is a real photograph subjected to plating and painting on the die-casting aluminum alloy according to the present invention.

4 is a real picture of the product produced by the die casting process using a comparative example.

Figure 5 is a table showing the content of each component of the die-casting aluminum alloy and Comparative Example of a preferred embodiment of the present invention.

Figure 6 is a table showing the strength and elongation measured for the die-casting aluminum alloy and the comparative example of a preferred embodiment of the present invention.

Figure 7 is a microstructure photograph of the die-casting aluminum alloy and comparative example of a preferred embodiment of the present invention.

8 is a table showing the grain size of the die casting aluminum alloy of the preferred embodiment of the present invention and the comparative example.

9 is a reliability test results for the plating layer formed in a preferred embodiment of the present invention.

10 is a reliability test results for the coating layer formed in a preferred embodiment of the present invention.

11 is a process flowchart showing a method of manufacturing an aluminum alloy for die casting according to the present invention.

Hereinafter, a die casting aluminum alloy according to the present invention will be described with reference to FIGS. 2 and 3.

Prior to this, the terms or words used in the present specification and claims should not be interpreted in the ordinary and dictionary sense, and the inventors may appropriately define the concept of terms in order to best explain their invention in the best way. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

Therefore, the embodiments described in the present specification and the configuration shown in the drawings are only preferred embodiments of the present invention, and do not represent all of the technical idea of the present invention, and various equivalents may be substituted for them at the time of the present application. It should be understood that there may be water and variations.

FIG. 2 is a real picture of a product produced by die casting the aluminum alloy for die casting according to the present invention, and FIG. 3 is a real picture of plating and painting on the die casting aluminum alloy according to the present invention.

The die-cast aluminum alloy according to the present invention has been developed to be excellent in formability in die casting operations, and to form a highly reliable plating layer and a coating layer 20 in plating and painting processes.

That is, as shown in FIG. 2, a product having a thin thickness can be molded well without cracks or unfilled, and the plating layer 10 and the coating layer 20 can be formed as shown in FIG. 3.

On the other hand, Figure 4 is a real picture of the product manufactured by the die casting process using a comparative example, it was confirmed that the cracking occurs in the inner bottom surface is low castability.

The reliability of the coating layer 20 and the plating layer 10 will be described in detail below.

Hereinafter, a composition of the die casting aluminum alloy will be described with reference to FIG. 5.

As shown in Figure 5, the die-casting aluminum alloy according to the present invention is added to silicon (Si), copper (Cu), iron (Fe), zinc (Zn), magnesium (Mg), manganese (Mn) And nickel (Ni) was configured to not be included.

In more detail, the die casting aluminum alloy is 8.5% to 10.5% of silicon (Si), 2.0% to 3.7% of copper (Cu), 1.0% or less of iron (Fe), and 1.0% to 5.0% by weight. Zinc (Zn), 0.6-1.0% magnesium (Mg), 0.4% or less of manganese (Mn) and the balance aluminum (Al) and other unavoidable impurities.

On the other hand, the comparative example shown in Figure 5 is configured so that any one of the main components of the aluminum alloy copper (Cu), zinc (Zn), magnesium (Mg), manganese (Mn).

In the aluminum alloy of the present invention, silicon (Si) improves the flowability of the molten metal and lowers the melting point, thereby increasing the castability of the aluminum alloy during the die casting process.

The lower melting point of the silicon (Si) to improve the productivity and improve the castability, it is included in the 8.5 to 10.5% of the total weight of the aluminum alloy. If more than 10.5% by weight of silicon (Si) is added, the amount of primary silicon (Si) is gradually increased to reduce the elongation, thereby increasing the brittleness of the product, the application of the die-casting process of electronic products having a thin thickness is not suitable.

The primary silicon (Si) is to act as a reinforcing material such as a composite material, while increasing the strength and hardness of the aluminum alloy but increases the brittleness.

Copper (Cu) is dissolved in the aluminum alloy to improve the strength and increase the machinability, and when added to exceed 3.7% by weight relative to the total weight of the aluminum alloy, the properties are lowered and the specific gravity increases, so it is included below 3.7% by weight. This is preferred.

Manganese (Mn) is included in less than 0.4% by weight and has the effect of increasing the corrosion resistance. However, if the content of manganese (Mn) exceeds 0.4% by weight is not preferable because the fluidity of the aluminum alloy is lowered to form coarse precipitates.

Magnesium (Mg) is dissolved in the addition of the aluminum alloy to improve the strength and in the embodiment of the present invention is included 0.6 ~ 1.0% by weight.

Since magnesium (Mg) causes oxidation on the surface of the molten metal, the content of magnesium in the molten metal is gradually reduced. In the embodiment of the present invention, magnesium (Mg) -calcium (Ca) was added using a master alloy.

Iron (Fe) plays an excellent role in preventing the squeeze of the mold, but if included in excess of 1.0% by weight will cause problems such as corrosion, it is preferably included in the content of 1.0% by weight or less.

Zinc (Zn) is a component having the effect of increasing the strength of the aluminum alloy and improving fluidity and corrosion resistance. In the embodiment of the present invention, zinc (Zn) is included 1.0 to 5.0% by weight. That is, zinc (Zn) is preferably added so as not to exceed 5.0% by weight since the specific gravity is increased when the addition amount is increased and the strength is not improved.

Hereinafter, with reference to the accompanying Figure 6 looks at the physical properties of the aluminum alloy configured as described above.

According to the content of the above configuration, the aluminum alloy according to the present invention has a tensile strength of 266 ~ 363 MPa, a yield strength of 243 ~ 266 MPa and a break elongation of 0.6 ~ 2.2%.

7 and 8 will be described by comparing the microstructure and grain size of the preferred embodiment and the comparative example of the present invention.

7 is a microstructure photograph of a die casting aluminum alloy and a comparative example of a preferred embodiment of the present invention, Figure 8 is a table showing the grain size of the die casting aluminum alloy and a comparative example of a preferred embodiment of the present invention.

As shown in FIG. 7, the aluminum alloy prepared according to the preferred embodiment of the present invention has a fine grain size, whereas the aluminum alloy of the comparative example has a coarse grain size as compared with the embodiment.

The finer the grain size of the aluminum alloy, the better the fluidity of the alloy is possible to manufacture a die-casting product having excellent surface conditions.

And, as shown in Figure 8, the aluminum alloy prepared according to the preferred embodiment of the present invention has an average cast grain size of 4.7 ㎛ or less, the aluminum alloy of the comparative example has a relatively large average cast grain size.

Surface treatment reliability of the aluminum alloy having the above configuration was evaluated and shown in FIGS. 9 and 10.

9 is a result of the reliability test for the plating layer 10 formed in the preferred embodiment of the present invention, Figure 10 is a result of the reliability test for the coating layer 20 formed in the preferred embodiment of the present invention.

Vibration abrasion test was performed for 60 minutes on the molded article formed with the plating layer 10 shown on the right side of FIG. 3 as shown in FIG. 9, but no damage to the surface occurred, and after peeling off the tape for 5 minutes after X-cut, At this time, no peeling of the plating layer 10 occurred.

In addition, 5% saline was sprayed on the sample that had been X-cut for 48 hours to confirm whether or not rust occurred.

As shown in FIG. 10, the RCA wear test was performed by applying a load of 275 g 33 times per minute to the molded article on which the coating layer 20 shown on the left side of FIG. 3 was formed.

In addition, peeling did not occur when the coating layer 20 was detached after attaching the tape for 5 minutes after X-cut.

Finally, 5% saline was sprayed for 72 hours on the X-cut sample to check for rust, but did not occur at all, meeting the requirements.

Hereinafter, a method of manufacturing the die casting aluminum alloy as described above will be described with reference to FIG. 11.

As shown in the drawing, the method for producing a die-casting aluminum alloy according to the present invention includes dissolving aluminum and an aluminum master alloy in a melting furnace (S100), and adding a magnesium-calcium master alloy to the melting furnace to complete the die-casting aluminum alloy. Completion step (S200) is made.

The die casting aluminum alloy made in the completion step (S200) is 8.5% to 10.5% of silicon (Si), 2.0 to 3.7% of copper (Cu), 1.0% or less of iron (Fe), and 1.0 to It is composed of 5.0% zinc (Zn), 0.6 ~ 1.0% magnesium (Mg), 0.4% or less manganese (Mn), balance aluminum (Al) and other unavoidable impurities, 700 ~ It has a remelting temperature of 750 ° C.

In addition, when the die casting is to be performed using the aluminum alloy, it is preferable to tap water in accordance with a temperature range of 660 to 700 ° C. In this case, the temperature of the die casting mold is preferably 250 to 300 ° C.

The scope of the present invention is not limited to the above-exemplified embodiments, and many other modifications based on the present invention may be made by those skilled in the art within the above technical scope.

The present invention is the addition of silicon (Si), copper (Cu), iron (Fe), zinc (Zn), magnesium (Mg), manganese (Mn) to aluminum (Al) of the die casting aluminum alloy with improved strength and elongation Manufacturing is possible.

Therefore, it is possible to provide a material suitable for the production of electronic-related parts, which requires precise dimensions and is mainly for mass production.

In addition, by adding nickel (Ni), which is a noxious element, it not only has eco-friendliness but also has a fine grain size, so that the surface treatment effect can be maximized and can be applied to exterior parts.

Claims

By weight% 8.5-10.5% silicon (Si), 2.0-3.7% copper (Cu), 1.0% or less iron (Fe), 1.0-5.0% zinc (Zn), 0.6-1.0% Die alloy aluminum alloy, comprising magnesium (Mg), 0.4% or less of manganese (Mn) and the remainder aluminum (Al) and other unavoidable impurities.
2. The aluminum alloy for die casting according to claim 1, having an average cast lip size of 4.7 mu m or less.
The die-casting aluminum alloy according to claim 2, which has a tensile strength of 266-363 MPa.
4. The die-casting aluminum alloy according to claim 3, which has a yield strength of 243 to 266 MPa.
The die-casting aluminum alloy according to claim 4, which has an elongation at break of 0.6 to 2.2%.
The aluminum alloy for die casting according to claim 5, wherein magnesium (Mg) is added using a magnesium (Mg) -calcium (Ca) mother alloy.
A dissolving step of dissolving aluminum and an aluminum master alloy in a melting furnace;

Magnesium-calcium master alloy was added to the furnace to make up the weight percent by weight of 8.5 to 10.5% of silicon (Si), 2.0 to 3.7% of copper (Cu), 1.0% or less of iron (Fe), and 1.0 to 5.0% of Complete die casting aluminum alloy containing zinc (Zn), 0.6-1.0% magnesium (Mg), manganese (Mn) below 0.4%, balance aluminum (Al) and other unavoidable impurities Die casting aluminum alloy manufacturing method, characterized in that consisting of a complete step.
The method of claim 7, wherein the die casting aluminum alloy has a remelting temperature of 700 ~ 750 ℃.