KR20080109388A - Aluminum alloy for die casting - Google Patents

Abstract

Aluminium alloy for the die-cast is provided to easily manufacture the high function auto part with the die-casting method. Aluminium alloy for die-cast characterizes to be formed the followings: Cu 4.0 ~ 5.0 weight%, Si 16 ~ 18 weight%, Mg 0.45 ~ 0.65 weight%, Z 0.5 ~ 1.5 weight%, Fe 0.4 ~ 1.3 weight%, Sn 0.005 ~ 0.02 weight%, Cr 0.005 ~ 0.02 weight%, Ti 0.01 ~ 0.02 weight%, Ca 0.005 ~ 0.02 weight%, Ni 0.02 ~ 0.04 weight%, Mn 0.07 ~ 0.09 weight%, Pb 0.04 ~ 0.06 weight% and the incidental impurity is mixed and dissolved to the temperature of 670‹C ~ 750‹C, solvent of 0.2 ~ 0.5 weight% is spread and stir for 5 ~ 20 minute. And perform the killing process maintaining the dissolved alloy for 15 minutes the half an hour to the temperature of 690‹C ~ 750‹C.

Description

Aluminum Alloy for Die Casting

The present invention relates to a die-cast aluminum alloy, and more particularly, has a higher strength, higher tensile strength and hardness, higher thermal conductivity as well as improved wear resistance and fluidity. High-performance automobile parts such as engines and missions can be easily manufactured by die-casting using aluminum alloy, and the elongation and expansion coefficient are low to minimize the internal defects such as shrinkage holes. The present invention relates to an aluminum alloy for die casting which can be greatly reduced.

Recently, as the interest in energy saving and environmental issues is increasing, many researches for lightening various transportation devices are being conducted.

In particular, the expected effects due to the lighter weight of automotive parts include improved engine efficiency through improved fuel economy and improved environmental problems due to reduced emissions.

As a result, in recent years, there has been a growing interest in aluminum alloys, which are lightweight materials, which have excellent specific strength, corrosion resistance and thermal conductivity, and which have excellent properties for steel materials and other materials in terms of recycling.

Automotive aluminum parts are usually produced by rolling, extruding, forging and casting. Among these aluminum parts, the casting occupies about 15% of the weight of the car, especially engines and missions that are directly related to driving performance. 80% of the weight of the unit is made of castings.

As described above, automotive aluminum parts are mostly cast by a die-casting method, and the aluminum alloy used here is mainly composed of Al-Si-based alloys, which are industrially applied to die-casting, and Al-Mg-based alloys, although small amounts. Is also used.

However, in the die cast method, since the molten metal is filled into the mold cavity at high speed and high pressure, it is difficult to replenish the molten metal against shrinkage of the final solidified portion by the solidification of the melted portion first rather than the cavity portion during filling solidification. Therefore, when manufacturing high-performance automobile parts such as engines and mission units directly related to driving performance using the conventional Al-Si alloys as described above, the strength is weak, tensile strength and hardness are low, and thermal conductivity The low elongation and expansion coefficient make it easy to have internal defects such as shrinkage holes. Therefore, the defective parts of the manufactured parts are not only high, but also the durability is lowered. Many restrictions are involved in manufacturing high-performance automobile parts such as There was.

Therefore, the object of the present invention is stronger than general aluminum alloy, high tensile strength and hardness, high thermal conductivity as well as high wear resistance and improved fluidity, such as high performance, such as engines, mission units directly related to driving performance Die casting aluminum can be easily manufactured by using die-casting method using aluminum alloy, and it has a low elongation and expansion coefficient so as to minimize the internal defects such as shrinkage holes and greatly reduce the defective rate of produced parts. To provide an alloy.

Another object of the present invention is to provide a die-cast aluminum alloy that can achieve the weight reduction of the automotive parts to improve the environmental problems due to the increase in engine efficiency and the reduction of emissions by improving the fuel economy of the vehicle.

In order to achieve the above object, the present invention is Cu 4.0 ~ 5.0 wt%, Si 16 ~ 18 wt%, Mg 0.45 ~ 0.65 wt%, Zn 0.5 ~ 1.5 wt%, Fe 0.4 ~ 1.3 wt%, Sn 0.005 ~ 0.02 wt% %, Cr 0.005 to 0.02 wt%, Ti 0.01 to 0.02 wt%, Ca 0.005 to 0.02 wt%, Ni 0.02 to 0.04 wt%, Mn 0.07 to 0.09 wt%, Pb 0.04 to 0.06 wt% and other incidental impurities After dissolving Al which occupies the remaining amount and dissolving it at a temperature of 670 ° C. to 750 ° C., the solution was stirred for 5 to 20 minutes by spraying with 0.2 to 0.5% by weight of a solvent, and then the dissolved alloy was 690 ° C. for 15 to 30 minutes. It provides a die-cast aluminum alloy, characterized in that through the killing process to maintain at a temperature of ~ 750 ℃.

Preferably, as the solvent, at least one or more of chloride, fluoride and silicon fluoride except for sodium salts is selected and used to provide an aluminum alloy for die casting.

More preferably, the chloride, fluoride and silicon fluoride except for sodium salts used as the solvent are used in anhydrous state to provide an aluminum alloy for die casting.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In order to form a die-cast aluminum alloy according to an embodiment of the present invention, first, Cu, Si, Mg, Zn, Fe, Sn, Cr, Ti, Ca, Ni, Mn, Pb and Al removed impurities It is mobilized.

The ratio of the die-cast aluminum alloy blended with a predetermined weight% of the above elements is determined as a result of combining the contents obtained through various experiments.

Cu 4.0-5.0 wt%, Si 16-18 wt%, Mg 0.45-0.65 wt%, Zn 0.5-1.5 wt%, Fe 0.4-1.3 wt%, Sn 0.005-0.02 wt%, Cr 0.005-0.02 wt%, Ti 0.01 to 0.02 wt%, Ca 0.005 to 0.02 wt%, Ni 0.02 to 0.04 wt%, Mn 0.07 to 0.09 wt%, Pb 0.04 to 0.06 wt%, and Al which occupies the remaining balance except incidental impurities. It is preferable to use any one selected from chloride, fluoride and silicon fluoride except for 0.2 to 0.5% by weight of sodium salt, and the solvent is preferably used in anhydrous state.

The Cu may improve the flowability, tensile strength and hardness of the alloy when more than 4.0 wt% is added, and at the same time improve the machinability and the problem that the molten metal adheres to the mold, but when an amount of more than 5.0 wt% is added. Since there is a problem in that elongation and corrosion resistance are lowered, Cu is most preferably added within 4.0 to 5.0% by weight.

In addition, the Si significantly improves the fluidity when added by more than 16% by weight, lowers the coefficient of thermal expansion and reduces the dimensional change, improves pressure resistance and wear resistance, but shrinks when an amount of more than 18% by weight is added It is most preferable to add within 16 to 18% by weight because not only there are many balls, but also the machinability is weakened.

In addition, when the Mg is added to 0.45% by weight or more, the intermetallic compound is greatly improved in the mechanical properties by precipitation hardening, but when the amount of more than 0.65% by weight is added, the fluidity is lowered and cause brittleness, so 0.45 ~ Most preferably added within 0.65% by weight.

In addition, when Zn is added in an amount of 2.5% by weight or less, the Zn serves to improve machinability without adversely affecting mechanical properties. However, when Zn is added in an amount of 2.5% by weight or less, it reduces the amount of hot brittleness and corrosion resistance. It is preferred to add, but most preferably it is added within 0.5 to 1.5% by weight.

In addition, the Fe is allowed to be added up to 1.3% by weight or less in order to prevent sticking to the mold during die casting. However, when an amount of more than 1.3% by weight is added, the strength is drastically lowered, and since it causes hot spots, the Fe is preferably added in an amount of 1.3% by weight or less, and appropriately 0.4% by weight. Most preferably added within% to 1.3% by weight.

In addition, Mn can improve the strength of the alloy by adding more than 0.07% by weight, improve the adverse effects of Fe and improve adhesion, but when added in an amount exceeding 0.09% by weight, Mn causes hot spots (Hot Spot). ) Is most preferably added within 0.07% to 0.09% by weight.

In addition, the Ti is effective in miniaturizing the crystal grains of the aluminum alloy and improving heat resistance, and the Ti is preferably added in 0.01 to 0.02% by weight.

In addition, the Ni is effective in improving the high temperature strength and heat resistance of the aluminum alloy, the Ni is preferably added in 0.02 ~ 0.04% by weight.

The above elements are blended at a predetermined weight percent, and then dissolved by heating to a melting temperature of 670 ° C to 760 ° C. If the melting temperature is too low below 670 ℃ sedimentation is difficult, if overheating above 760 ℃ causes oxidation or gas absorption, so the melting temperature is preferably 670 ℃ ~ 760 ℃, if overheated above 760 ℃ It is preferable to solidify the molten metal and then dissolve it again.

After dissolving as described above, the solvent is sprayed with 0.2 to 0.5% by weight of the dissolved metal to the dissolved metal and then stirred slowly to prevent segregation for 5 to 20 minutes. Here, at least one of chlorides, fluorides, and silicon fluorides except sodium salts is preferably used as the solvent, and chlorides, fluorides, and silicon fluorides except sodium salts are mostly deliquescent, so they may be used as solvents. At the time of use, it is preferable to use in anhydrous state.

As described above, the solvent sprayed on the molten metal reacts with aluminum to generate bubbles, and the bubbles generated as described above are raised. The bubbles rising as above rises by adsorbing or including oxides, and since the bubbles have no hydrogen concentration, hydrogen is diffused in the bubbles to absorb hydrogen from the molten metal and degassing. However, the bubble generated as described above requires a rising time of the bubble to rise on the molten surface, so a killing process is required.

Thus, after spraying the solvent as described above, in order to separate the gas or oxide in the molten metal, the die is subjected to a killing process for 15 to 30 minutes while maintaining the temperature of the molten metal at 690 캜 to 750 캜. Is cast by Since the diecast method used herein is a technically used technology, a detailed description thereof will be omitted.

The strength, tensile strength, elongation, hardness, specific gravity, thermal conductivity, and coefficient of expansion of the die cast alloy and the general aluminum alloy according to the present invention as described above are given in KS B 0801, KS B 5521, KS B 0801, KS B 0803, KS Table 1 shows the results of the experiment based on B 5541 and the Bennell hardness test.

division Plain aluminum alloy Die Casting Aluminum Alloy Strength (0.2% Deflection) 150 250 Tensile Strength (MPa) 310 320 Elongation (%) 3.5 1 or less Hardness (HB) 83 108 importance 2.71 2.73 Thermal Conductivity (W / (m · k)) 96 134 Coefficient of expansion (℃) 22 18

Table Mechanical and physical properties comparison table of the general aluminum alloy and the die-cast aluminum alloy, that is, the strength, tensile strength, elongation, hardness, specific gravity of the die-cast aluminum alloy according to an embodiment of the present invention as shown in Table 1 , Thermal conductivity and coefficient of expansion were 250 (0.2% deformation) and tensile strength was tested according to KS B 0801, KS B 5521, KS A 0021, KS B 0803, KS B 5541, and Bennell hardness test method. The strength is 320MPa, the elongation is below 1%, the hardness is 108HB, the specific gravity is 2.73, the thermal conductivity is 134 (W / (m · k)), the coefficient of expansion is 18 (℃), By using aluminum alloy, high-performance automobile parts such as engines, missions, etc., which are directly related to driving performance, have high strength, high tensile strength and hardness, high thermal conductivity, high wear resistance and good fluidity. It can be easily manufactured by the test method, and the elongation and expansion coefficient can be reduced to minimize internal defects such as shrinkage holes, thereby greatly reducing the defective rate of the produced product, and can also improve durability and reduce the weight of automobile parts. In this way, it is possible to improve environmental efficiency due to increased engine efficiency and reduced emission of gas through improved fuel economy of the vehicle.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by those skilled in the art without departing from the gist of the present invention as claimed in the claims. Of course, such changes will fall within the scope of the claims.

As described above, according to the present invention, according to the present invention, Cu 4.0-5.0 wt%, Si 16-18 wt%, Mg 0.45-0.65 wt%, Zn 0.5-1.5 wt%, Fe 0.4-1.3 wt%, Sn 0.005-0.02 Excluding weight percent, Cr 0.005 to 0.02 weight percent, Ti 0.01 to 0.02 weight percent, Ca 0.005 to 0.02 weight percent, Ni 0.02 to 0.04 weight percent, Mn 0.07 to 0.09 weight percent, Pb 0.04 to 0.06 weight percent and incidental impurities Die-cast aluminum alloy made of Al, which accounts for the remaining amount, has a higher strength, higher tensile strength and hardness, higher thermal conductivity, higher abrasion resistance, and better fluidity than other aluminum alloys. High-performance automobile parts such as mission units can be easily manufactured by die-casting using aluminum alloy, and defects in products produced by minimizing internal defects such as shrinkage holes due to low elongation and expansion coefficient Can be greatly reduced, durability can be improved, and the weight of automobile parts can be reduced, thereby improving the fuel efficiency of the vehicle and improving the environmental problems caused by the increase of engine efficiency and the emission of exhaust gas. There is.

Claims (3)

Cu 4.0-5.0 wt%, Si 16-18 wt%, Mg 0.45-0.65 wt%, Zn 0.5-1.5 wt%, Fe 0.4-1.3 wt%, Sn 0.005-0.02 wt%, Cr 0.005-0.02 wt%, Ti 670 ℃ ~ by blending 0.01 ~ 0.02% by weight, Ca 0.005 ~ 0.02% by weight, Ni 0.02 ~ 0.04% by weight, Mn 0.07 ~ 0.09% by weight, Pb 0.04 ~ 0.06% by weight, and Al which occupies the remaining balance except incidental impurities After dissolving at a temperature of 750 ° C, stirring by 0.2 to 0.5% by weight of solvent, stirring for 5 to 20 minutes, and then killing the molten alloy for 15 to 30 minutes at a temperature of 690 ° C to 750 ° C. Die-cast aluminum alloy, characterized in that through the composition. The method of claim 1, As the solvent, at least one or more of chloride, fluoride and silicon fluoride except for sodium salts is selected and used. The method of claim 2, Chloride, fluoride and silicon fluoride, except for sodium salts used as the solvent, are used in the anhydrous state, the die-cast aluminum alloy.