KR20160044617A

KR20160044617A - Alloy for die-casted automotive parts and manufacturing method thereof

Info

Publication number: KR20160044617A
Application number: KR1020140138797A
Authority: KR
Inventors: 강희삼
Original assignee: 현대자동차주식회사
Priority date: 2014-10-15
Filing date: 2014-10-15
Publication date: 2016-04-26
Also published as: US20160108500A1; DE102015203759A1; CN105986154A; KR101620204B1

Abstract

Disclosed are an alloy for die casting a component, and a manufacturing method thereof. The manufacturing method of an alloy for die casting a component of the present invention comprises: aluminum (Al) as a main ingredient; 8.0-10.5 wt% of magnesium (Mg); 1.9-3.4 wt% of silicon (Si); 0.4-2.0 wt% of copper (Cu); 0.3-1.0 wt% of manganese (Mn); beryllium (Be) maximum of 50 ppm; and other unavoidable impurities. Mg/Si is inserted in a mold at a speed faster than or equal to 3.0 m/s by heating 3.1-4.3 of the molten metal at a temperatures of 670-730°C. According to the present invention, the alloy for die casting a component is capable of reducing weight, reduce production costs, and improve durability.

Description

TECHNICAL FIELD The present invention relates to an alloy for a die casting component,

The present invention relates to an alloy for a die casting part and a method of manufacturing the same, and more particularly to an alloy for a die casting part to which a light corrosion resistant aluminum alloy is applied, and a method for manufacturing the same.

The ADC10 / 12 alloy used in automotive die casting parts is generally used because of its low cost and excellent castability.

However, as the driving environment becomes increasingly harsh, damage due to lack of durability, which has not appeared in automotive parts, has been increasing. The ADC10 / 12 alloy is gradually showing its limitations due to the seawater salinity or the occurrence of white rods due to the build material, and the need for a new alloy to overcome this problem is emerging.

In addition, in recent years, countries around the world have been striving to restrain environmental pollution by strengthening various environmental regulations. As a result, environmental regulations are becoming increasingly severe. To cope with this situation, in the automobile industry, While continuing to do so, we are finding it difficult to find alternatives that have the basic performance and cost competitiveness to replace conventional commercial alloys.

It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present invention and is not to be construed as adhering to the prior art already known to those skilled in the art.

Japanese Patent Application Laid-Open No. 2007-100205 (April 19, 2007) Korean Patent Publication No. 10-2012-0057402 (Jun. 25, 2012)

The present invention solves the problems of the prior art by improving the durability by more than 40% by developing die casting parts using high strength and high corrosion resistant aluminum alloy, It is an object of the present invention to provide an alloy for a die casting part which can achieve weight reduction of about 7% in the same shape by lowering the density, thereby making it possible to reduce weight, cost and durability in various aluminum die casting parts and a manufacturing method thereof .

In order to achieve the above object, the alloy for a die casting part according to the present invention comprises aluminum (Al) as a main component, 8.0 to 10.5% by weight of magnesium (Mg), 1.9 to 3.4% (Mn) of 0.3 to 1.0% by weight, beryllium (Be) of 50 ppm or more and other unavoidable impurities, and Mg / Si of 3.1 to 4.3.

The amount of the Al-Mg-Cu intermetallic compound produced is 7.0% or more.

A tensile strength of 300 MPa or more and a yield strength of 170 MPa or more.

Al-Mg-Cu intermetallic compound as a main strengthening phase is dispersed and distributed in an aluminum matrix, and Mg ₂ Si particles are distributed together.

And the Mg ₂ Si particle size is 10 to 30 μm.

In order to accomplish the above object, the present invention provides a method for manufacturing an alloy for a die casting component, comprising: a step of forming an alloy containing aluminum (Al) as a main component, 8.0 to 10.5% by weight of magnesium (Mg), 1.9 to 3.4% ), 0.4 to 2.0 wt% of manganese (Mn), 0.3 to 1.0 wt% of manganese (Mn), 50 ppm of beryllium (Be) and other inevitable impurities, and Mg / Si of 3.1 to 4.3 is heated to 670 to 730 캜, And is injected into the mold at a speed of 3.0 m / s or higher.

The present invention is advantageous because of the technical structure described above.

According to the alloy for a die casting part of the present invention and the manufacturing method thereof, the durability can be improved by more than 40% by developing a die casting part using a high strength, high corrosion resistant aluminum alloy, There is an advantage that can be solved.

In addition, it is possible to achieve a weight reduction of about 7% in the same shape by lowering the density, thereby making it possible to reduce weight, cost, and durability in various aluminum die casting parts.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a comparison of microstructures of the prior art compared to the present invention,
FIG. 2 is a view showing the occurrence of hot cracks according to a high injection speed,
3 is a view showing a result of fluidity evaluation according to the temperature of the molten metal.

Hereinafter, an alloy for a die casting component and a method of manufacturing the same according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

The alloy for a die casting part of the present invention comprises aluminum (Al) as a main component and 8.0 to 10.5% by weight of magnesium (Mg), silicon (Si), and the like in order to realize light weight, high strength, (Cu) of 0.4 to 2.0% by weight, manganese (Mn) of 0.3 to 1.0% by weight, beryllium (Be) of 50 ppm and other unavoidable impurities. The Mg / Si ratio for formation and proper distribution of the Al-Mg-Cu intermetallic compound is limited to 3.1 to 4.3.

In this connection, the present inventors have limited the Mg / Si ratio to 1.98 to 2.5 in order to suppress the formation of intermetallic compounds while adding Mg, Si and Cu for various researches and experiments, And the like, an alloy having a quasi-binary system structure of Al-Mg ₂ Si was obtained.

However, as the alloy content of these alloys increases, the process conditions for obtaining the desired quasicrystalline process structure are very limited and there is a problem that the quality dispersion must be increased.

Accordingly, the present invention improves the Mg / Si ratio and realizes a complex microstructure in which a large amount of Al-Mg-Cu intermetallic compound and superfine Mg ₂ Si are produced on the microstructure, It is possible to provide an alloy having high strength, low density and high corrosion resistance compared with commercial alloys.

FIG. 1 is a photograph of a microstructure photograph of an alloy produced by the present invention and a quasi-binary system structure mentioned in the prior art.

As shown in FIG. 1, the alloy of the present invention is an Al-Mg-Cu system (main strengthening phase), which is a main strengthening phase, compared to a quasi-binary system structure in which Mg ₂ Si particles are finely distributed in a conventional aluminum matrix White) intermetallic compounds are uniformly distributed, and it is confirmed that primary Mg ₂ Si particles (black) having a size of 10 to 30 μm are distributed together.

When the Mg ₂ Si grains exceed 30 μm, it is difficult to produce an alloy having a tensile strength of 300 MPa and a yield strength of 170 MPa or more, which is the target in the present invention. When the Mg ₂ Si grains are less than 10 μm, Is produced.

This is different from conventional alloys that maximize the elongation by maintaining the ratio of other alloying elements in addition to Mg, and securing the microstructure around the superalloy aluminum resin phase.

The reason for limiting the numerical value of the alloy composition for a die casting part of the present invention will be described below.

Mg is the most important element for realizing high strength, high corrosion resistance and low density characteristics which are main characteristics of the present alloy, and its content is limited to 8.0 to 10.5% by weight.

When Mg is added in an amount of less than 8.0 wt%, the amount of the Al-Mg-Cu intermetallic compound that can be produced is insufficient so that the desired level of Al-Mg-Cu intermetallic compound can not be obtained when Si is added, , The amount of the intermetallic compound capable of realizing the high corrosion resistance property is decreased, and the desired physical properties can not be obtained.

When it is added in an amount of more than 10.5% by weight, problems of coarsening and hot crack generation of the Al-Mg-Cu intermetallic compound occur and the casting and mechanical properties are deteriorated.

Si is a composition for improving the casting of the alloy, and its content is limited to 1.9 to 3.4% by weight.

When Si is added in an amount of less than 1.9%, the effect of improving the casting composition is insignificant. When added in an amount exceeding 3.4%, Mg ₂ Si particles are produced in excess in place of the main reinforcing particles, i.e., Al-Mg-Cu intermetallic compounds. There is a problem that the strength is lowered.

In order to obtain optimized high strength and high corrosion resistance, the ratio of Mg / Si should be controlled within the range of 3.1 ~ 4.3.

If the Mg / Si ratio is less than 3.1, the Si size becomes large, and if the Mg / Si ratio exceeds 4.3, Mg ₂ Si particles are not produced.

In the case of Cu, an Al-Mg-Cu intermetallic compound, which is a strengthening phase, is formed with Mg. When the addition amount is less than 0.4%, the strengthening effect is insignificant. When the content exceeds 2.0%, an intermetallic compound And the corrosion resistance is lowered.

In the case of Mn, it is added in order to improve the problem of die dissolution occurring during the die casting process. When the addition of Mn is less than 0.3%, the effect of improving the adhesion is insignificant. When the addition of Mn exceeds 1% And the strength is lowered.

The element Be, which is a micro element, suppresses the oxidation of the surface during the melting of the alloy containing a large amount of Mg, thereby suppressing the generation of oxide inclusions in the product. can do.

The method for producing an alloy for a die casting part of the present invention is a method for producing the alloy for a die casting part as described above and is characterized in that a filling failure problem , Problems of occurrence of hot cracks and casting defects due to shrinkage voids are improved. In other words, the method of manufacturing an alloy for a die casting part of the present invention prevents hot crack, unfilled, shrinkage defect, etc. by applying casting process conditions (melt temperature, injection rate, cooling time, etc.) different from existing die casting process conditions It is possible to secure mass productivity, thereby solving the problem of lack of durability and backlash which existing die casting parts have, and there is an advantage that light weighting effect can be obtained at the same time.

Since the fluidity of the alloy of the present invention is lower than that of the ADC10 / 12 alloy, the temperature of the molten metal must be at least 670 ° C. and Mg content is relatively high. It is preferable to limit the maximum temperature to 730 占 폚.

In addition, since the alloy of the present invention has a high coexistence interval with respect to the ADC10 / 12 alloy, it is necessary to shorten the filling time as much as possible. Therefore, a fast injection speed of at least 3.0 m / s or more should be secured, And shall be limited to 10 points.

The present inventors varied the Mg content to determine the amount of Al-Mg-Cu intermetallic compound that affects high strength / high corrosion resistance characteristics of Al-Mg-Si alloy, And the production amount was confirmed.

division Al Mg (wt%) Si (wt%) Al-Mg-Cu intermetallic compound production amount (%) Comparative Example 1 Remainder 7.5 3.0 4.0 Comparative Example 2 Remainder 8.0 3.0 5.0 Example 1 Remainder 8.5 3.0 7.0 Example 2 Remainder 9.0 3.0 8.0 Example 3 Remainder 9.5 3.0 9.5 Example 4 Remainder 10.0 3.0 10.5 Example 5 Remainder 10.5 3.0 12.0

As shown in Table 1, when Mg is added in an amount of 8.0% or more, a sufficient amount of an intermetallic compound is produced. The amount of the intermetallic compound increases proportionally with the Mg content, but when Mg is added in an amount exceeding 10.5%, hot cracks are generated, which increases the possibility of a defect rate in the casting process.

In order to confirm the high strength characteristics of the Al-Mg-Si-Cu alloy, the present inventors varied the Cu content of the Al-10Mg-3Si alloy and confirmed the mechanical properties. The results are shown in Table 2.

division Al Mg (wt%) Si (wt%) Cu (wt%) The tensile strength
(MPa) Yield strength
(MPa) Comparative Example 3 Remainder 10.0 3.0 0.3 280 160 Example 6 Remainder 10.0 3.0 0.4 310 175 Example 7 Remainder 10.0 3.0 0.5 325 185 Example 8 Remainder 10.0 3.0 0.7 325 210 Example 9 Remainder 10.0 3.0 0.9 335 220

As shown in Table 2, the mechanical properties of the Al-Mg-Si based alloy were improved as the Cu content increased.

In order to obtain a target strength of 300 MPa or more, Cu should be added in an amount of 0.4% or more.

Like Mg, Cu has the effect of improving the mechanical properties in proportion to the increase of the content. However, when it is added in an excess amount exceeding 2.0%, the corrosion resistance due to the potential difference corrosion is lowered.

FIG. 2 is a view showing the occurrence of hot cracks according to the change of the injection speed of the molten metal.

As shown in FIG. 2, when the same molten metal satisfying the alloy composition of the present invention was used, the hot cracks occurred at the high feed rates of 2.4, 2.6 and 2.8 m / s, When the high speed injection rate was 3.0 m / s, the hot cracks disappeared and a good quality product was obtained.

FIG. 3 shows the results of an experiment for evaluating the fluidity of the molten metal. As a result of an experiment using the same molten metal satisfying the alloy composition of the present invention, it was found that the molten metal can secure sufficient fluidity of the molten metal at a temperature of 670 ° C. or higher .

As described above, according to the alloy for a die casting part of the present invention and the method for producing the same, the durability can be improved by 40% or more through development of a die casting part using a high strength and high corrosion resistant aluminum alloy, There is an advantage that the problem of the white back can be solved.

Claims

(Al) as a main component, and contains 8.0 to 10.5 wt% of magnesium (Mg), 1.9 to 3.4 wt% of silicon (Si), 0.4 to 2.0 wt% of copper (Cu), 0.3 to 1.0 wt% of manganese (Be) of at most 50 ppm and other unavoidable impurities, and Mg / Si of 3.1 to 4.3.

The method according to claim 1,
Wherein an Al-Mg-Cu intermetallic compound is produced in an amount of 7.0% or more.

The method according to claim 1,
A tensile strength of 300 MPa or more and a yield strength of 170 MPa or more.

The method according to claim 1,
Wherein an Al-Mg-Cu intermetallic compound as a main strengthening phase is dispersed and distributed in an aluminum matrix, and Mg ₂ Si particles are distributed together.

The method of claim 4,
Wherein the Mg ₂ Si particle size is 10 to 30 탆.

(Al) as a main component, and contains 8.0 to 10.5 wt% of magnesium (Mg), 1.9 to 3.4 wt% of silicon (Si), 0.4 to 2.0 wt% of copper (Cu), 0.3 to 1.0 wt% of manganese Characterized in that the molten metal (Be) has a maximum of 50 ppm and other unavoidable impurities, and the molten metal having a Mg / Si ratio of 3.1 to 4.3 is heated to 670 to 730 캜 and is injected into the mold at a rate of 3.0 m / Wherein