KR101800548B1 - High tensile strength and high thermal conductivity aluminum alloy with good castability - Google Patents

Abstract

The present invention relates to an aluminum alloy, comprising: 3.5-4.5 wt% of zinc (Zn); 1.1-2.0 wt% of magnesium (Mg); 0.1-0.4 wt% of iron (Fe); 0.1-0.3 wt% of titanium (Ti); and the remaining composed of aluminum (Al) and unavoidable impurities, thereby providing an aluminum alloy having excellent castability, high strength, and high thermal conductivity. According to the present invention, the aluminum alloy having excellent castability, high strength, and high thermal conductivity has a thermal conductivity of 150W/mK or more and a tensile strength of 200MPa or more by adding zinc (Zn) as a main alloy element and controlling components of magnesium (Mg), iron (Fe) and titanium (Ti), and at the same time, there is little cracking during casting. As such, the present invention is advantageous in casting.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high strength and high thermal conductivity aluminum alloy,

The present invention relates to a high strength and high thermal conductivity aluminum alloy excellent in casting composition and more particularly to an aluminum alloy including zinc (Zn), magnesium (Mg), iron (Fe) and titanium And a high thermal conductivity aluminum alloy having excellent thermal conductivity and good castability.

Aluminum alloy has light weight, excellent electric conductivity and thermal conductivity, and is applied to various fields such as automobile, aircraft, transportation machinery parts, building materials, electric appliance parts, power lines, electronic devices, and packaging.

Aluminum alloys are divided into aluminum alloys for casting and aluminum alloys for plastic working such as extrusion and rolling according to the production method. About 20% of all aluminum products are produced by aluminum alloys for plastic processing such as extrusion and rolling, % Is produced from aluminum alloy for casting, aluminum alloy for casting is very high in aluminum industry.

On the other hand, as the aluminum alloy for die casting, an Al-Si alloy and an Al-Mg alloy are mainly used as shown in Table 1 below. However, Al-Si alloys or Al-Mg alloys have excellent castability but low thermal conductivity of 90 ~ 130 W / mK.

Aluminum alloy specification Aluminum alloy system Thermal conductivity (W / mK) KS JIS AA ALDC 2 ADC 3 360 Al-Si 113 ALDC 7 ADC 10 380 Al-Si 96 ALDC 8 ADC 12 384 Al-Si 92 ALDC 4 ADC 6 515 Al-Mg 96 ALDC 3 ADC 5 518 Al-Mg 130

Recently, in industrial fields such as electric, electronic and automobile industries, in order to positively respond to market demands such as improvement of energy efficiency, heat dissipation efficiency and output improvement of equipment, It is necessary to develop a heat dissipation component using an aluminum alloy for casting having good thermal conductivity.

However, until now, aluminum alloys for casting having the same level of castability and tensile strength and having a thermal conductivity of 150 W / mK or more have not been developed as compared with conventional aluminum alloys for casting, so that the thermal conductivity is 90 to 130 W / mK Al-Si-based alloys and Al-Mg-based alloys are used as aluminum alloys for casting.

Meanwhile, the present inventors have proposed an alloy for casting which exhibits excellent thermal conductivity as compared with a conventional aluminum alloy for casting, as disclosed in the following patent documents. These alloys have a high thermal conductivity of at least 150 W / mK, There was a limit in terms of composition.

1. Korean Patent Registration No. 10-1469613

The technical problem to be solved by the technical idea of the present invention is to improve the thermal conductivity of 150 W / mK or more by controlling the content of magnesium (Mg), iron (Fe) and titanium (Ti) Or more and at the same time less cracking during casting, thereby providing a high strength and high thermal conductivity aluminum alloy having excellent castability.

However, these problems are illustrative, and the technical idea of the present invention is not limited thereto.

According to an aspect of the present invention, there is provided a high strength and high thermal conductivity aluminum alloy having excellent castability, comprising 3.5 to 4.5% by weight of zinc (Zn), 1.1 to 2.0% by weight of magnesium (Mg) To 0.4% by weight of titanium (Ti) and 0.1 to 0.3% by weight of titanium (Ti), the balance being aluminum (Al) and inevitable impurities.

In some embodiments of the present invention, the thermal conductivity of the aluminum alloy may be greater than 150 W / mK.

In some embodiments of the present invention, the tensile strength of the aluminum alloy may be greater than 200 MPa.

In some embodiments of the present invention, the content of titanium (Ti) may be 0.13-0.21 wt%.

In some embodiments of the present invention, the molten aluminum alloy is injected into a casting crack test mold maintained at a temperature of 200 ° C, the crack is measured after the molten alloy has solidified, and a casting crack The sensitivity may be less than 50.

[Formula 1]

HTS = Σ (W _crack f _length f _location )

(Where HTS is the crack sensitivity, W _crack is the crack width factor, f _length is the crack length factor, and f _location is the crack location factor, and the cast crack crack test mold is 237.5 mm in length and 27.5 mm in diameter, And four rod-like cavities each having a length of 57 mm, 95 mm, 122.5 mm, and 140 mm and a diameter of 10 mm, each of which has a spherical constraint point at one end thereof and at the other end to constrain shrinkage upon solidification. )

The aluminum alloy according to the technical idea of the present invention has a thermal conductivity of 150 W / mK or more and a thermal conductivity of 200 MPa or more through control of components of magnesium (Mg), iron (Fe) and titanium (Ti) Tensile strength at the same time as cracking during casting is small and castability is excellent.

The high strength and high thermal conductivity aluminum alloy having excellent main composition according to the present invention can be suitably used for manufacturing electrical, electronic and automotive heat dissipation parts requiring high thermal conductivity and excellent tensile strength and castability.

The effects of the present invention described above are exemplarily described, and the scope of the present invention is not limited by these effects.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of a die for cast crack cracking test carried out in an embodiment of the present invention. Fig.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. The scope of technical thought is not limited to the following examples. Rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will fully convey the scope of the invention to those skilled in the art. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items. The same reference numerals denote the same elements at all times. Further, various elements and regions in the drawings are schematically drawn. Accordingly, the technical spirit of the present invention is not limited by the relative size or spacing depicted in the accompanying drawings.

The high strength and high thermal conductivity aluminum alloy excellent in casting composition according to the present invention comprises 3.5 to 4.5% by weight of zinc (Zn), 1.1 to 2.0% by weight of magnesium (Mg), 0.1 to 0.4% by weight of iron (Fe) To 0.3% by weight, the balance being aluminum (Al) and inevitable impurities. The aluminum alloy may have a thermal conductivity of 150 W / mK or more and a tensile strength of 200 MPa or more.

An alloy element capable of improving casting due to the suppression of casting cracks in aluminum, an alloy element capable of obtaining solid solution and precipitation strengthening effect of aluminum solid solution and precipitation in an aluminum base metal, It has a thermal conductivity of 150 W / mK or more and a tensile strength of 200 MPa or more by simultaneously adding alloying elements that can minimize a decrease in thermal conductivity due to a very low solubility in metal, and at the same time, It is characterized by.

The reasons for the addition and content of each alloy element are as follows.

Zinc (Zn) is an alloy element which is added to aluminum as an alloy element to improve the casting composition and increase the tensile strength in accordance with the effect of solidification and precipitation strengthening. If the zinc content is less than 3.5% by weight, the tensile strength of the cast alloy is lowered so that the tensile strength of 200 MPa or more can not be obtained. If the content exceeds 4.5 wt%, the thermal conductivity of the cast alloy is lowered, and thermal conductivity of 150 W / mK or more can not be obtained.

Magnesium (Mg) is an element which can be added to aluminum as an alloy element to improve the casting composition and increase the tensile strength in accordance with the effect of solidification and precipitation strengthening. If the content of magnesium is less than 1.1% by weight, the tensile strength of the cast alloy is lowered, so that the tensile strength of 200 MPa or more can not be obtained, and the content of magnesium Is more than 2.0% by weight, the thermal conductivity of the cast alloy is lowered and the thermal conductivity of 150 W / mK or more can not be obtained.

Iron (Fe) has a very low solubility in aluminum at normal temperature of 0.052% by weight, and after casting it is mainly crystallized as an intermetallic compound such as Al ₃ Fe. Therefore, it is added to aluminum to increase the strength while minimizing deterioration of thermal conductivity of aluminum And at the same time, it is an alloying element which can reduce mold seizure when molding an aluminum alloy product by die casting. It is preferable that 0.1 to 0.4% by weight of iron is added to the aluminum alloy according to the present invention. If the content of iron is less than 0.1% by weight, the effect of preventing mold sticking is lowered. When molding the product by die casting, (Fe-rich phase) is excessively crystallized in the cast alloy, thereby lowering the casting of the alloy. This is because the Fe-rich phase is excessively crystallized in the cast alloy when the content of Fe exceeds 0.4 wt%.

Titanium (Ti) is an alloy element which is added to aluminum as an alloy element and is precipitated on an aluminum base metal by an intermetallic compound such as Al ₃ Ti by precipitation hardening heat treatment to increase the tensile strength. In addition, And is an alloying element capable of obtaining crystal grain refinement, alloy fluidity, and crack prevention effect of the cast material. If the content of titanium is less than 0.1% by weight, the effect of preventing casting cracks of the cast alloy can not be obtained. If the content of titanium is more than 0.3% by weight, And the thermal conductivity of 150 W / mK or more can not be obtained.

In particular, the content of the titanium (Ti) may be 0.13-0.21 wt%. When the content of titanium (Ti) is 0.13-0.21% by weight, it is possible to maintain a thermal conductivity of 150 W / mK or more and an excellent tensile strength of 200 MPa or more, and to have an excellent casting crack prevention effect.

Inevitable impurities are impurities which are unintentionally mixed by the raw material or the manufacturing apparatus in the process of producing the alloy according to the present invention. For example, Cu, Cr, Co, V, Mn, Li, Ni, These components of the impurities are kept at 0.1 wt% or less, preferably 0.01 wt% or less, so as not to affect the alloy characteristics.

The casting crack sensitivity defined by the following formula 1 may be 50 or less by measuring the crack after the molten aluminum alloy is injected into a casting crack test mold maintained at a temperature of 200 ° C and the alloy melt is solidified.

[Formula 1]

HTS = Σ (W _crack f _length f _location )

Here, HTS is the crack sensitivity, W _crack is the crack width factor, f _length is the crack length factor, and f _location is the crack location factor. The cast crack crack test mold is 237.5 mm long and 27.5 mm in diameter, And four rod-like cavities each having a length of 57 mm, 95 mm, 122.5 mm and 140 mm and a diameter of 10 mm, each of which has a spherical constraint point at which one end is connected and the other end is capable of restraining shrinkage upon solidification.

As described above, the aluminum alloy according to the present invention has a thermal conductivity of 150 W / mK or more and a thermal conductivity of 200 MPa or more by controlling the components of magnesium (Mg), iron (Fe) and titanium (Ti) Tensile strength at the same time as cracking during casting is small and castability is excellent.

The high strength and high thermal conductivity aluminum alloy having excellent main composition according to the present invention can be suitably used for manufacturing electrical, electronic and automotive heat dissipation parts requiring high thermal conductivity and excellent tensile strength and castability.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, details of the present invention will be described with reference to examples and experimental examples.

The high strength and high thermal conductivity aluminum alloy excellent in cast composition according to the embodiment of the present invention will be described in detail with reference to Tables 2 to 4 below.

The present inventors prepared an alloy having the composition shown in the following Table 2 by a melt-agitated aluminum alloy manufacturing method commonly used in the manufacture of an alloy for casting, in order to produce a high strength and high heat conductivity aluminum alloy having excellent main composition.

alloy Composition (% by weight) Zn Mg Ti Fe Al Example One 3.70 1.15 0.21 0.30 94.56 2 3.79 1.50 0.13 0.13 94.36 3 3.70 1.91 0.18 0.15 93.98 Comparative Example 4 3.63 1.06 - 0.10 95.19 5 3.77 1.57 - 0.11 94.45 6 3.76 1.91 - 0.12 94.14

Specifically, a raw material of an aluminum alloy was prepared so as to have a composition as shown in Table 2, and then charged into an electric resistance type melting furnace to dissolve the raw materials in the atmosphere to prepare a molten metal. Thereafter, casting molds were used for casting cracking Test specimens were prepared to measure the main composition and tensile strength and thermal conductivity of the alloys were measured.

For casting evaluation essential for alloy casting, a cast crack evaluation generally carried out in a manner well known in the industry (cast crack evaluation is performed by cast alloy cracking test as in FIG. 2 with the alloy melt held at a temperature of 200 캜 And the casting crack sensitivity is measured as shown in Equation [1] after the molten alloy is solidified.

[Formula 1]

HTS = Σ (W _crack f _length f _location )

Herein, HTS is the crack sensitivity, W _crack is the crack width factor, f _length is the crack length factor, and f _location is the crack position factor. The cast crack crack test mold has a sprue length of 237.5 mm and a diameter of 27.5 mm, And four rod-shaped cavities each having a length of 57 mm, 95 mm, 122.5 mm, and 140 mm and a diameter of 10 mm, each of which has a spherical constraint point capable of restricting shrinkage upon solidification at the other end.

Table 3 below shows the results of evaluating the casting crack resistance (casting crack sensitivity) of each alloy according to the embodiment of the present invention and each of the alloys according to the comparative example.

Alloy (wt%) Zn Mg Ti Fe Al Casting crack sensitivity Example One 3.70 1.15 0.21 0.30 94.56 35 2 3.79 1.50 0.13 0.13 94.36 46 3 3.70 1.91 0.18 0.15 93.98 30 Comparative Example 4 3.63 1.06 - 0.10 95.19 144 5 3.77 1.57 - 0.11 94.45 70 6 3.76 1.91 - 0.12 94.14 53

As can be seen from the above Table 3, the aluminum alloys according to the embodiments of the present invention have a casting crack sensitivity lower than that of the aluminum alloys according to the comparative example, and thus have excellent casting characteristics.

In Example 1 and Comparative Example 4, the zinc content was about 3.7 wt% and the magnesium content was about 1.1 wt%, which was similar to each other. In Example 1, 0.21 wt% of titanium was added. As a result, It has low casting crack sensitivity and excellent castability.

In Example 2 and Comparative Example 5, the zinc content was about 3.7% by weight and the magnesium content was about 1.5% by weight. In Example 1, 0.13% by weight of titanium was added so that Example 2 was compared with Comparative Example 5 It has low casting crack sensitivity and excellent castability.

In Example 3 and Comparative Example 6, the zinc content was about 3.7% by weight and the magnesium content was about 1.9% by weight. In Example 3, 0.18% by weight of titanium was added. As a result, It has low casting crack sensitivity and excellent castability.

In other words, from the results of evaluating the casting crackability, which is an index for evaluating the casting composition, the aluminum alloys according to the present invention all have a casting crack sensitivity of 50 or less and have excellent castability in comparison with the aluminum alloys according to the comparative example.

As to the thermal conductivity, which is one of the main objects of the alloy according to the embodiment of the present invention, the conductivity of the specimen manufactured first is measured at room temperature by using a conductivity meter and then converted into a conversion formula of the following formula Thermal conductivity was obtained. Tensile strengths were obtained by testing tensile specimens made from each alloy according to the present invention and each alloy according to the comparative example.

[Formula 2]

K = 5.02? T x 10 ^-9 + 0.03

Here, K is the thermal conductivity,? Is the conductivity, and T is the absolute temperature.

Table 4 shows the thermal conductivity and tensile strength of each alloy according to the embodiment of the present invention and each alloy according to the comparative example.

Alloy (wt%) Zn Mg Ti Fe Al Thermal conductivity
(W / mK) The tensile strength
(MPa) Example One 3.70 1.15 0.21 0.30 94.56 151 207 2 3.79 1.50 0.13 0.13 94.36 153 261 3 3.70 1.91 0.18 0.15 93.98 151 280 Comparative Example 4 3.63 1.06 - 0.10 95.19 177 187 5 3.77 1.57 - 0.11 94.45 160 218 6 3.76 1.91 - 0.12 94.14 159 251

As shown in Table 4, the aluminum alloys according to the embodiment of the present invention all have a thermal conductivity of 150 W / mK or more and a tensile strength of 200 MPa or more at the same time.

In other words, the aluminum alloy according to the embodiment of the present invention has an excellent casting property due to low casting crack sensitivity as compared with the aluminum alloy according to the comparative example, and simultaneously has a thermal conductivity of 150 W / mK or more and a tensile strength of 200 MPa or more.

Accordingly, the aluminum alloy according to the embodiment of the present invention can be suitably used as an aluminum material for casting, which requires good castability and excellent thermal conductivity and tensile strength.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. Will be apparent to those of ordinary skill in the art.

Claims (5)

(Al), and the balance of aluminum (Al) and aluminum (Al), in the range of from 3.5 to 4.5 wt% of zinc, 1.1 to 2.0 wt% of magnesium, 0.1 to 0.4 wt% of iron and 0.1 to 0.3 wt% of titanium It is a high-strength and high-heat conductivity aluminum alloy which is made of unavoidable impurities and excellent in casting.
Wherein the aluminum alloy has a thermal conductivity of 150 W / mK or more and is excellent in castability.
delete The method according to claim 1,
Wherein the aluminum alloy has a tensile strength of 200 MPa or more.
The method according to claim 1,
Wherein the content of titanium (Ti) is 0.13-0.21 wt%.
The method according to claim 1,
The molten aluminum alloy was injected into a casting crack test mold maintained at a temperature of 200 DEG C and cracks were measured after the alloy melt was solidified to determine the casting crack sensitivity defined by the following formula High thermal conductivity aluminum alloy.
[Formula 1]
HTS = Σ (W _crack f _length f _location )
(Where HTS is the crack sensitivity, W _crack is the crack width factor, f _length is the crack length factor, and f _location is the crack location factor, and the cast crack crack test mold is 237.5 mm in length and 27.5 mm in diameter, And four rod-like cavities each having a length of 57 mm, 95 mm, 122.5 mm, and 140 mm and a diameter of 10 mm, each of which has a spherical constraint point at one end thereof and at the other end to constrain shrinkage upon solidification. )

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