KR20210096889A - Alumium alloy for die-casting - Google Patents

Abstract

According to an embodiment of the present invention, based on the total weight, an aluminum alloy for die-casting may contain: 3 to 12 wt% of zinc (Zn); 0.2 to 1 wt% of magnesium (Mg); 6.5 to 8.5 wt% of silicon (Si); 2 to 4 wt% of copper (Cu); 0.7 to 1.1 wt% of iron (Fe); 0.1 wt% or less of manganese (Mn); 0.1 wt% or less of nickel (Ni); and the balance aluminum (Al).

Description

Aluminum alloy for die casting

The present invention relates to an aluminum alloy for die casting.

Recently, portable terminals such as smart phones have been manufactured with a large screen and a thin screen. In order to apply such a large-screen thinned structure, it is necessary to secure the strength of the structure, and in order to secure the strength of the structure, a metal material is applied as an interior/exterior material of a portable terminal.

In particular, aluminum can be used in all fields of industry because it is light, has good corrosion resistance and machinability, and has high electrical and thermal conductivity as well as various types of high-functional alloys with other metals.

In order for the aluminum alloy to be used as an interior/exterior material of a portable terminal, predetermined conditions for strength and thermal conductivity must be satisfied. Values such as strength and thermal conductivity may vary depending on the composition of the aluminum alloy.

On the other hand, die-casting (die-casting) may be used as a method for molding the interior / exterior material of the portable terminal. Die casting is one of the casting methods, and it is a precision casting method in which molten metal is injected into a steel mold precisely machined to match the casting shape to obtain a casting identical to that of the mold.

In the case of using the die-casting method, the composition of the aluminum alloy must be determined so that die-casting can have a castability.

The inventor of the present invention has researched an aluminum alloy for die casting having high strength and thermal conductivity for a long time and has completed the present invention after trial and error.

An object of the present invention is to provide an aluminum alloy for die casting that can be used as an interior/exterior material of a portable terminal.

Other objects not specified in the present invention will be further considered within the scope that can be easily inferred from the following detailed description and effects thereof.

According to an aspect of the present invention, in the aluminum alloy for die casting, 3 to 12% by weight of zinc (Zn), 0.2 to 1% by weight of magnesium (Mg), 6.5 to 8.5% by weight of silicon (Si), based on the total weight ), 2 to 4 wt% copper (Cu), 0.7 to 1.1 wt% iron (Fe), 0.1 wt% or less manganese (Mn), 0.1 wt% or less nickel (Ni), and the balance is aluminum (Al) An aluminum alloy for die casting is provided, including.

The yield strength may be 250Mpa or more, and the thermal conductivity may be 120W/m·K or more.

The elongation at break may be 1 to 3%.

Based on the total weight, 0.005 wt% or less of titanium (Ti), less than 0.001 wt% of tin (Sn), and 0.002 wt% or less of chromium (Cr) may further include impurities including at least one.

Based on the total weight, 9 to 10% by weight of zinc (Zn), 0.5 to 0.7% by weight of magnesium (Mg), 7 to 8% by weight of silicon (Si), 2 to 3% by weight of copper (Cu), 0.7 to 1 wt% of iron (Fe), 0.1 wt% or less of manganese (Mn), 0.1 wt% or less of nickel (Ni), and the balance may include aluminum (Al).

According to another aspect of the present invention, there is provided a structure manufactured by a die casting method using the aluminum alloy for die casting.

It may be used as at least one of an interior material and an exterior material of an electronic device.

Zinc (Zn) may be contained in an amount of 8 to 12 wt% based on the total weight.

High strength and high heat dissipation interior / exterior material can be obtained by using the aluminum alloy for die casting according to an embodiment of the present invention.

The aluminum alloy for die casting according to an embodiment of the present invention may have sufficient castability and thus may be die-cast.

On the other hand, even if it is an effect not explicitly mentioned herein, it is added that the effects described in the following specification expected by the technical features of the present invention and their potential effects are treated as described in the specification of the present invention.

1 and 2 are graphs of tensile test results of an aluminum alloy for die casting according to an embodiment of the present invention.
3 and 4 are graphs of tensile test results of an aluminum alloy for die casting according to a comparative example.
5 is a view showing a die-casting mold for die-casting the aluminum alloy for die-casting according to an embodiment of the present invention.
6 is a photograph of a structure obtained by die casting an aluminum alloy for die casting according to an embodiment of the present invention.
7 is a diagram illustrating a structure in which a die-casting aluminum alloy for die-casting according to an embodiment of the present invention is applied to an electronic device.
It is revealed that the accompanying drawings are exemplified by reference for understanding the technical idea of the present invention, and the scope of the present invention is not limited thereby.

In the description of the present invention, if it is determined that the subject matter of the present invention may be unnecessarily obscured as it is obvious to those skilled in the art with respect to related known functions, the detailed description thereof will be omitted.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, an embodiment of an aluminum alloy for die casting according to the present invention will be described in detail with reference to the accompanying drawings. A description will be omitted.

The present invention provides a composition material of an alloy for die casting, in particular, an aluminum alloy, and a composition ratio thereof.

The aluminum alloy according to the present invention has sufficient castability, so that it is possible to easily die-cast a casting (product) of a desired shape. In addition, the aluminum alloy according to the present invention has excellent yield strength and thermal conductivity, and a product made through die casting with such an alloy also has excellent yield strength and thermal conductivity.

Table 1 below shows the composition material and the composition ratio range of the aluminum alloy for die casting according to an embodiment of the present invention (unit: wt%).

Zn Mg Si Cu Fe Mn Ni Al 3.0~12.0 0.2~1.0 6.5~8.5 2.0~4.0 0.7~1.1 0.1 max 0.1 max balance

The aluminum alloy according to the present invention may include aluminum (Al), zinc (Zn), magnesium (Mg), silicon (Si), copper (Cu), iron (Fe), manganese (Mn), and nickel (Ni). can

The aluminum alloy according to the present invention contains 3 to 12 wt% of zinc (Zn), 0.2 to 1 wt% of magnesium (Mg), 6.5 to 8.5 wt% of silicon (Si), and 2 to 4 wt% based on the total weight. of copper (Cu), 0.7 to 1.1 wt% of iron (Fe), 0.1 wt% or less of manganese (Mn), 0.1 wt% or less of nickel (Ni), and the balance may include aluminum (Al).

The zinc (Zn) component may improve strength and castability in the alloy. Zinc (Zn) may be added in an amount of 3 to 12 wt% based on the total weight of the entire alloy. If the zinc (Zn) content is less than 8% by weight relative to the total weight, the effect of improving mechanical properties such as strength and castability is not sufficiently exhibited, and if it exceeds 12% by weight, corrosion resistance and toughness may be deteriorated.

Preferably, zinc (Zn) may be contained in an amount of 8 to 12 wt% based on the total weight.

Magnesium (Mg) component can improve strength and provides advantageous advantages for weight reduction. Magnesium (Mg) may be added in an amount of 0.2 to 1 wt% based on the total weight of the entire alloy. If the magnesium (Mg) content is less than 0.2 wt %, the effect of improving strength may not be sufficiently exhibited, and if the magnesium (Mg) content exceeds 1 wt %, corrosion resistance may be lowered and the fluidity of the molten metal may be lowered, thereby reducing workability.

The aluminum alloy for die casting according to the present invention contains a relatively large amount of magnesium compared to a conventional aluminum alloy containing the same composition material, and the magnesium content according to the present invention does not decrease corrosion resistance and fluidity (workability) It has technical significance in that it is a composition that can achieve the purpose of strengthening the product.

Silicon (Si) is chemically bonded to magnesium (Mg) and _{precipitated as Mg 2} Si to control mechanical properties, and residual silicon (Si) remaining after bonding with magnesium (Mg) is precipitated alone to improve mechanical properties, It can be used as an effective ingredient for improving the fluidity of molten metal. Silicon (Si) may be added in an amount of 6.5 to 8.5 wt% based on the total weight of the entire alloy. If the silicon (Si) content is less than 6.5 wt%, fluidity may be reduced, and if it exceeds 8.5 wt%, moldability may be deteriorated.

The copper (Cu) component may improve strength and hardness in the alloy. Copper (Cu) may be added in an amount of 2 to 4 wt% based on the total weight of the entire alloy. If the copper (Cu) content is less than 2% by weight, the improvement in mechanical properties of the alloy may be insignificant, and if it exceeds 4% by weight, corrosion resistance and elongation may be reduced.

The iron (Fe) component may reduce the adhesiveness of the die casting mold to improve demoldability and reduce mold erosion. Iron (Fe) may be added in an amount of 0.7 to 1.1 wt% based on the total weight of the entire alloy. If the iron (Fe) content is less than 0.7 wt%, the demolding of the casting is reduced, and if it exceeds 1.1 wt%, it is combined with Al and Si to form precipitates, and may reduce the corrosion resistance of the aluminum alloy.

The manganese (Mn) component can improve the mechanical properties of the alloy through solid solution strengthening and dispersion of fine precipitates by precipitating the _{Mn-Al 6 phase.} Manganese (Mn) may be added in an amount of 0.1 wt% or less based on the total weight of the entire alloy. When the manganese (Mn) content exceeds 0.1 wt %, workability may be deteriorated due to adhesion.

The nickel (Ni) component may improve the heat resistance of the alloy. Nickel (Ni) may be added in an amount of 0.1 wt% or less based on the total weight of the entire alloy. If the nickel (Ni) content exceeds 0.1% by weight, it may cause corrosion of the alloy.

The aluminum (Al) component is the main material of the aluminum alloy, and may be added in an amount of 73 wt % or more based on the total weight of the entire alloy. The purity of the aluminum used may be 99%.

The aluminum alloy according to the present invention may contain unavoidable impurities.

The impurities may include at least one of 0.005 wt% or less of titanium (Ti), 0.001 wt% or less of tin (Sn), and 0.002 wt% or less of chromium (Cr), based on the total weight.

The titanium (Ti) component may play a role in refining the crystal grains of the alloy, thereby exhibiting a crack prevention effect. Titanium (Ti) may be added in an amount of 0.005 wt % or less based on the total weight of the entire alloy. When the titanium (Ti) content exceeds 0.005 wt %, a _{large amount of a compound such as TiAl 3} may be produced and mechanical properties of the alloy may be deteriorated.

The tin (Sn) component may improve the formability and machinability of the alloy. Tin (Sn) may be added in an amount of less than 0.001 wt % based on the total weight of the entire alloy. When the tin (Sn) content is 0.001 wt % or more, the workability of the alloy may be reduced.

The chromium (Cr) component may improve abrasion resistance through crystal grain refinement. Chromium (Cr) may be added in an amount of 0.002 wt % or less based on the total weight of the entire alloy. When the chromium (Cr) content exceeds 0.002, the strength of the alloy may be reduced.

Impurities may include metals other than titanium, tin, and chromium. The impurities may be added in an amount of 0.01 wt % or less based on the total weight of the alloy.

Preferably, the aluminum alloy according to the present invention comprises 9 to 10% by weight of zinc (Zn), 0.5 to 0.7% by weight of magnesium (Mg), 7 to 8% by weight of silicon (Si), 2 to 3 wt% copper (Cu), 0.7 to 1 wt% iron (Fe), 0.1 wt% or less manganese (Mn), 0.1 wt% or less nickel (Ni), and the balance comprises aluminum (Al), , may further contain unavoidable impurities

The composition ratio range of the aluminum alloy is described in Table 2 below, and the impurity composition ratio is omitted in Table 2 (unit: wt%).

Zn Mg Si Cu Fe Mn Ni Al 9.0 to 10.0 0.5~0.7 7.0~8.0 2.0~3.0 0.7~1.0 0.1 max 0.1 max balance

Table 3 below shows the specific composition ratio of the aluminum alloy according to the present invention. Example 1 is a composition ratio of a sample taken from molten metal, and Example 2 is a composition ratio of a sample taken from a sprue. Meanwhile, the molten metal was prepared by melting an aluminum alloy composition at 700°C.

ingredient Zn Mg Si Cu Fe Mn Ni Ti Sn Cr Al Example 1 9.54 0.55 7.83 2.55 0.88 0.009 0.003 0.005 <0.001 0.002 balance Example 2 9.61 0.55 7.65 2.62 0.79 0.007 0.002 0.005 <0.001 0.001 balance Example 3 9.63 0.57 7.53 2.64 0.76 0.006 0.001 0.004 - 0.001 balance

The yield strength of the aluminum alloy for die casting according to the present invention is 250Mpa or more, and the thermal conductivity may be 120W/m·K or more. Preferably, the yield strength of the aluminum alloy for die casting according to the present invention is greater than 250Mpa, and the thermal conductivity may be greater than 120W/m·K. The yield strength and thermal conductivity may be the yield strength and thermal conductivity measured during die casting of an aluminum alloy. In addition, the yield strength and thermal conductivity may be the yield strength and thermal conductivity of a product finished by die casting of an aluminum alloy.

In general, when the composition ratio is changed in the same composition material, when the yield strength increases, the thermal conductivity decreases, and when the yield strength decreases, the thermal conductivity increases. It has a technical meaning in that it has a value.

The elongation at break (%) of the aluminum alloy for die casting according to the present invention may be 1 to 3. Such elongation at break may be elongation at break measured during die casting of an aluminum alloy for die casting.

The melting point of the aluminum alloy for die casting according to the present invention may be 650 to 750 ℃. Preferably, the melting point of the aluminum alloy for die casting according to the present invention may be 700 ℃.

The following Table 4 shows the yield strength and thermal conductivity during die casting of the aluminum alloy for die casting according to Examples 1 to 3 of Table 3.

Example Yield strength (MPa) Thermal conductivity (W/m·K) Example 1 292.5 121 Example 2 255.2 130 Example 3 365.5 125

1 and 2 are graphs of tensile test results of an aluminum alloy for die casting according to an embodiment of the present invention.

1 is a graph (stress strain curves) showing the physical property test results of an aluminum alloy for die casting according to the present invention. 1 is a graph showing the test results of the aluminum alloy according to Example 1 of Table 3. In addition, the following Table 5 shows the specific test results of FIG. 1 .

exam number Yield strength (MPa) Maximum strength (MPa) Elongation (%) One 281.45 388.77 2.02 2 293.61 344.08 1.02 3 303.41 341.28 0.87 4 291.33 326.26 0.79 Average 292.45 350.1 1.17

1 and Table 5, the yield strength of the aluminum alloy for die casting according to Example 1 was derived as an average of 292.5 MPa.

2 is a graph (stress strain curves) showing the physical property test results of the aluminum alloy for die casting according to the present invention. 2 is a graph showing the test results of the aluminum alloy according to Example 2 of Table 3. In addition, the following Table 6 shows specific test results of FIG. 2 .

exam number Yield strength (MPa) Maximum strength (MPa) Elongation (%) One 255.67 383.46 2.6 2 254.88 370.43 2.19 3 255.52 376.28 2.34 4 259.6 385.01 2.51 5 250.29 380.22 2.54 Average 255.19 379.08 2.44

2 and Table 6, the yield strength of the aluminum alloy for die casting according to Example 2 was derived as an average of 255.2 Mpa.

Table 7 below shows a comparative example for an aluminum alloy containing the same or similar composition material (unit: wt%).

ingredient Zn Mg Si Cu Fe Mn Ni Al Comparative Example 1 12.61 0.09 7.21 2.70 1.17 0.45 0.45 75 Comparative Example 2 0.1 2.0 7 - - 0.1 0.05 90.12 Comparative Example 3 2 0.1 5 0.5 0.1 0.1 0.01 90.73 Comparative Example 4 - 0.01 8 1.2 0.6 0.15 0.06 89.88

3 and 4 are graphs of tensile test results of an aluminum alloy for die casting according to a comparative example.

3 is a graph showing the test results of the aluminum alloy according to Comparative Example 1 of Table 7. Comparative Example 1 has a higher zinc (Zn) content and a lower magnesium (Mg) content than the present invention.

Referring to FIG. 3 , it can be seen that the yield strength of Comparative Example 1 is lower than 250 MPa.

4 is a graph showing the test results of the aluminum alloy according to Comparative Example 2 of Table 7. Comparative Example 2 is different from the present invention in that the zinc (Zn) content is lower, the magnesium (Mg) content is higher, and there are no copper (Cu) and iron (Fe) components.

Referring to FIG. 4 , it can be seen that the yield strength of Comparative Example 2 is lower than 250 MPa.

Compared with Comparative Examples 1 and 2, it is possible to obtain an aluminum alloy having sufficient yield strength according to the present invention.

Comparative Example 3 has a lower zinc (Zn) content and a lower magnesium (Mg) content than the present invention. In addition, Comparative Example 4 is different from the present invention in that the magnesium (Mg) content is lower and there is no zinc (Zn) component.

Table 8 below shows the yield strength and thermal conductivity of the aluminum alloys according to Comparative Examples 3 and 4.

comparative example Yield strength (MPa) Thermal conductivity (W/m·K) Comparative Example 3 150 96 Comparative Example 4 158 155.6

In the case of Comparative Example 3, it can be seen that both the yield strength and the thermal conductivity were lower than those of the present invention. In the case of Comparative Example 4, it can be seen that the yield strength is lower than that of the present invention.

Compared with Comparative Examples 3 and 4, it is possible to obtain an aluminum alloy having sufficient yield strength and thermal conductivity according to the present invention.

The present invention provides a structure manufactured by a die casting method using an alloy for die casting, in particular, an aluminum alloy.

The above-mentioned aluminum alloy composition becomes a product (structure) by a die-casting method. In the die casting method, the prepared aluminum alloy composition is melted in a melting furnace, and the alloy melt is supplied to a die casting mold to form a casting (product).

If the casting temperature of the die casting is low, a problem occurs in the mold fillability due to the decrease in fluidity, and if the temperature is high, there is a risk of cracking because the shrinkage rate during solidification increases. Then, the casting can be manufactured with a casting pressure of 70~75Mpa.

5 is a view showing a die-casting mold for die-casting the aluminum alloy for die-casting according to an embodiment of the present invention.

Referring to FIG. 5 , the die casting mold 100 includes a fixed side template (upper plate) (Cavity Retainer Plate) 110 and a movable side template (lower plate) (Core Retiainer Plate) 120 . The fixed-side template 110 constitutes an empty space concavely made so that molten metal flows, that is, the cavity 111 . The movable side template 120 constitutes a shape made convex, that is, a core 121 . When the movable-side template 120 moves and is coupled to the fixed-side template 110 , the cavity 111 and the core 121 are combined to provide a molding space capable of forming the shape of the product.

The movable-side template 120 is moved and coupled to the fixed-side template 110, and the ejector 130 melts the aluminum alloy melt according to the present invention through the nozzle 122 of the movable-side template 120 in the forming space. eject The cooling water is circulated and the melt is cooled in the forming space. The movable-side template 120 is separated from the fixed-side template 110, and in the process, the finished casting (product) is separated.

6 is a photograph of a structure obtained by die casting an aluminum alloy for die casting according to an embodiment of the present invention. 7 is a diagram illustrating a structure in which a die-casting aluminum alloy for die-casting according to an embodiment of the present invention is applied to an electronic device.

Referring to FIG. 6 , the product was mass-produced in the same shape by a die-casting mold. Such a product may be used as at least one of an interior material and an exterior material of an electronic device. For example, a structure manufactured using an aluminum alloy according to the present invention may be used as at least one of a housing, a frame, and a bezel of an electronic device.

7 is a view showing an electronic device 10 having an exterior material 11 made through die casting with an aluminum alloy according to the present invention.

Although a smartphone is shown as an electronic device in FIG. 7 , the electronic device is a mobile phone, a smartphone, as well as a tablet personal computer (PC), a mobile phone, a video phone, and an e-book reader (e- book reader), desktop PC (desktop personal computer), laptop PC (laptop personal computer), netbook computer, workstation, server, PDA (personal digital assistant), PMP (portable multimedia player), MP3 It may include at least one of a player, a mobile medical device, a camera, and a wearable device.

The protection scope of the present invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it is added once again that the protection scope of the present invention cannot be limited due to obvious changes or substitutions in the technical field to which the present invention pertains.

10: electronic device
11: Exterior material
100: die casting mold

Claims (8)

In the aluminum alloy for die casting,
3 to 12% by weight of zinc (Zn), 0.2 to 1% by weight of magnesium (Mg), 6.5 to 8.5% by weight of silicon (Si), 2 to 4% by weight of copper (Cu), 0.7 to 1.1 wt% of iron (Fe), 0.1 wt% or less of manganese (Mn), 0.1 wt% or less of nickel (Ni), and the balance comprising aluminum (Al),
Aluminum alloy for die casting. According to claim 1,
Yield strength is 250Mpa or more, and thermal conductivity is 120W/m·K or more,
Aluminum alloy for die casting. According to claim 1,
The elongation at break is 1 to 3%,
Aluminum alloy for die casting. According to claim 1,
Based on the total weight, 0.005 wt% or less titanium (Ti), less than 0.001 wt% tin (Sn), 0.002 wt% or less further comprising impurities comprising at least one of chromium (Cr),
Aluminum alloy for die casting. According to claim 1,
Based on the total weight, 9 to 10% by weight of zinc (Zn), 0.5 to 0.7% by weight of magnesium (Mg), 7 to 8% by weight of silicon (Si), 2 to 3% by weight of copper (Cu), 0.7 to 1 wt% of iron (Fe), 0.1 wt% or less of manganese (Mn), 0.1 wt% or less of nickel (Ni), and the balance comprising aluminum (Al),
Aluminum alloy for die casting. According to claim 1,
Zinc (Zn) is contained in 8 to 12% by weight based on the total weight,
Aluminum alloy for die casting. A structure manufactured by a die-casting method using the aluminum alloy for die-casting according to at least one of claims 1 to 6. 8. The method of claim 7,
A structure used as at least one of an interior material and an exterior material of an electronic device.

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