KR20150071796A - Method of fabricating Al-Si casting alloy - Google Patents

Abstract

The present invention relates to a method for fabricating an aluminum alloy capable of improving mechanical properties including tensile strength or yield strength. The present invention provides the method for fabricating an Al-Si series aluminum alloy for casting which comprises the steps of: providing an aluminum alloy molten metal which contains aluminum (Al) and silicone (Si) and further contains copper (Cu); applying vibration energy to the aluminum alloy molten metal; and coagulating the aluminum alloy molten metal to which the vibration energy is applied.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing an Al-Si-based casting alloy,

The present invention relates to a method for producing an Al-Si based aluminum alloy, and more particularly, to an aluminum alloy for Al-Si based casting and a method of manufacturing the same.

The Al-Si-based cast aluminum alloy, which realizes an aluminum alloy containing silicon by a casting method, has excellent castability and is widely used for manufacturing parts for automobiles and industrial machines. Methods for improving the mechanical properties of Al-Si-based cast aluminum alloys known so far include a method of controlling the solidification rate to make the structure finer or a method of controlling the microstructure through the heat treatment process after solidification.

However, studies for further improving the mechanical properties including the tensile strength and the yield strength of Al-Si-based cast aluminum alloys have been continuously attempted. An object of the present invention is to provide a production method capable of further increasing the strength of an Al-Si-based casting aluminum alloy containing silicon of various compositions. However, these problems are exemplary and do not limit the scope of the present invention.

A process for producing an Al-Si-based cast aluminum alloy according to one aspect of the present invention is provided. The method for producing an Al-Si-based casting aluminum alloy includes the steps of providing an aluminum alloy melt containing aluminum (Al) and silicon (Si) and further comprising copper (Cu) And coagulating the aluminum alloy melt to which the vibration energy is applied.

In the above method for producing an Al-Si-based casting aluminum alloy, the step of providing an aluminum alloy melt containing aluminum and silicon and further comprising copper may be carried out by forming aluminum and a sub- The method comprising the steps of: providing a molten aluminum alloy containing silicon in an amount capable of reacting with silicon and further comprising copper.

The method for producing an Al-Si-based casting aluminum alloy may further include a step of performing solution treatment and aging-curing after the step of solidifying the aluminum alloy melt to which the vibration energy is applied. The step of performing the solution treatment and aging curing may include a step of precipitating and curing by a precipitate containing copper formed in the aluminum matrix of the Al-Si-based cast aluminum alloy.

In the method of manufacturing an Al-Si-based casting aluminum alloy, the step of applying vibration energy to the aluminum alloy melt may include applying ultrasonic waves or pulses to the aluminum alloy melt.

In the method for producing an Al-Si-based casting aluminum alloy, the silicon in the Al-Si-based casting aluminum alloy may constitute 1.65% to 30% by weight.

In the above method for producing an Al-Si-based casting aluminum alloy, the amount of the copper in the Al-Si-based casting aluminum alloy may be 0.5 wt% to 15 wt%.

In the method for producing an Al-Si-based casting aluminum alloy, the aluminum alloy molten metal may be at least one selected from the group consisting of magnesium, zinc, manganese, chromium, nickel, titanium, vanadium, zirconium, iron, tin, cobalt, Or more.

In the method for producing an Al-Si-based casting aluminum alloy, the aluminum alloy molten metal may further include ceramic particles.

 An Al-Si-based cast aluminum alloy according to another aspect of the present invention is provided. The Al-Si-based cast aluminum alloy is realized by the above-described manufacturing method.

According to one embodiment of the present invention as described above, by applying vibration energy to an aluminum-silicon melt containing copper, a large amount of copper element can be solid-dissolved in an aluminum base, and Al-Si having improved age hardening and tensile properties An aluminum alloy for a system casting can be provided. Of course, the scope of the present invention is not limited by these effects.

1 is a flow chart showing a method for producing an aluminum alloy for Al-Si-based casting according to embodiments of the present invention.
FIGS. 2A and 2B are diagrams illustrating a state diagram of aluminum-silicon for explaining a method of manufacturing an Al-Si-based cast aluminum alloy according to some embodiments of the present invention.
Fig. 3 is a conceptual illustration of a structure for solution treatment and aging hardening in a method for producing an Al-Si-based cast aluminum alloy according to some embodiments of the present invention.
4A is a graph showing the electrical resistance of an aluminum alloy including copper when ultrasonic treatment is performed according to some embodiments of the present invention.
4B is a graph showing changes in microhardness of an aluminum alloy including copper when ultrasonic treatment is performed according to some embodiments of the present invention.
5 is a graph showing high cyclic fatigue characteristics according to the presence or absence of ultrasonic treatment in an Al-Si-based cast aluminum alloy according to an embodiment of the present invention.
6A is an optical microscope photograph showing the microstructure of an Al-Si-based cast aluminum alloy according to a comparative example of the present invention.
6B is an optical microscope photograph showing the microstructure of an Al-Si-based cast aluminum alloy according to an embodiment of the present invention.
7 is a photograph of a secondary phase of an Al-Si-based cast aluminum alloy according to an embodiment of the present invention.
7 is a photograph of an aged precipitate of an Al-Si-based cast aluminum alloy according to an embodiment of the present invention.

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

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified into various other forms, The present invention is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will fully convey the concept of the invention to those skilled in the art. In the drawings, the thickness and size of each layer are exaggerated for convenience and clarity of explanation.

Like numbers refer to like elements throughout the specification. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

In the figures, for example, variations in the shape shown may be expected, depending on manufacturing techniques and / or tolerances. Accordingly, the embodiments of the present invention should not be construed as limited to the particular shapes of the regions shown herein, but should include, for example, changes in shape resulting from manufacturing.

FIG. 1 is a flowchart showing a method of manufacturing an Al-Si-based casting aluminum alloy according to an embodiment of the present invention. FIGS. 2A and 2B are views showing an Al- FIG. 3 is a view illustrating a state diagram of an aluminum-silicon for explaining a method of manufacturing an Al-Si-based cast aluminum alloy according to some embodiments of the present invention. As shown in FIG.

Referring to FIG. 1, a method of manufacturing an Al-Si-based cast aluminum alloy according to some embodiments of the present invention includes the steps of forming aluminum (Al) and silicon (Si) (S100) of applying the vibration energy to the molten aluminum alloy (S200), applying a vibration energy to the molten aluminum alloy (S200), and solidifying the molten aluminum alloy to which the vibration energy is applied (S300). Further, in the method of manufacturing an Al-Si-based casting aluminum alloy according to some embodiments of the present invention, a casting as-cast formed by solidifying the aluminum alloy melt is subjected to solution treatment (S400) of performing a solution treatment and aging-curing (S500) the solution casting.

In general, an Al-Si based aluminum alloy having 1.65% or more silicon added to aluminum has excellent castability and is widely used for manufacturing parts for automobiles and industrial machines. In order to improve the mechanical properties of the aluminum alloy for Al-Si-based casting, in addition to the method of controlling the solidification rate to make the structure finer or the method of controlling the microstructure through the heat treatment step after solidification, State microstructural properties of the alloy in the molten alloy. To this end, in the present invention, a method of applying vibration energy to a molten Al-Si-Cu alloy containing 0.5 wt% or more of copper added to an Al-Si alloy was used. In the present invention, ultrasound waves or pulse waves may be applied to apply vibration energy, but it is not limited thereto and any type of vibration energy may be applied.

This method of applying vibration energy to the molten metal is characterized in that the aluminum alloy for Al-Si-based casting has a process composition with a silicon content of 12.6 wt% or less, a silicon content of about 12.6 wt%, a silicon content of 12.6 wt% (Fig. 2A and Fig. 2B). [0052] As shown in Fig. In the case of the sub-process composition, the content of silicon is preferably 1.65% by weight or more for casting the Al-Si-based casting aluminum alloy. For the mechanical properties such as solidification shrinkage and elongation, % Or less. Meanwhile, the process composition forming the boundary between the sub-process composition and the over-process composition may be varied depending on the kind of the alloy element (for example, magnesium, copper, iron) which is further added to the alloy.

It can be explained that the applied vibration energy exhibits the following two effects. Firstly, Al-Al, Al-Si, Si-Si and Al-Cu bonds may exist in the molten Al-Si-Cu alloy. This reduces ordering and this effect can increase the solubility of copper in the aluminum matrix. Second, the vibration energy has the effect of increasing the local pressure inside the molten metal, and the increase in the pressure of the molten metal can increase the solubility of copper in the aluminum base.

The inventors of the present invention have found that, when compared with the case where the alloy melt of the above composition is cast by a conventional method that does not apply vibration energy, when the casting is performed by applying vibration energy to the alloy melt of the above composition (step S100- (S300)), it was confirmed that the mechanical strength of the aluminum alloy for Al-Si-based casting was improved by increasing the solid solution strengthening effect in the cast state.

Further, even in the case of performing the heat treatment (solubilization / aging treatment) of the material in the cast state (in the case of performing the steps (S400) to (S500) in Fig. 1), since the initial high capacity is high, The precipitation hardening effect was increased and the mechanical properties of the aluminum alloy for Al-Si-based casting were improved.

In the Al-Si-based cast aluminum alloy according to the embodiments of the present invention, copper constitutes 0.5% to 15% by weight, and strictly 1.5% to 5.0% by weight can be constituted.

Meanwhile, according to the modified embodiment of the present invention, various alloying elements may be added to the molten metal to change the characteristics of the Al-Si-based cast aluminum alloy according to the characteristics required for the Al-Si-based casting aluminum alloy. For example, in step S100 shown in Fig. 1, at least one selected from the group consisting of magnesium, zinc, manganese, chromium, nickel, titanium, vanadium, zirconium, iron, tin, cobalt, More than one can be added.

According to another modified embodiment of the present invention, ceramic particles can be added to the molten metal according to the characteristics required for the Al-Si-based casting aluminum alloy, thereby changing the characteristics of the Al-Si-based casting aluminum alloy. In this case, the Al-Si-based cast aluminum alloy to which the ceramic particles are added can be understood as an aluminum alloy composite material. For example, in step S100 shown in FIG. 1, ceramic particles such as SiC, Al ₂ O _3, and / or B ₄ C may be added to the Al-Si alloy melt.

The Al-Si-based cast aluminum alloy or aluminum alloy composite material described above can be realized by any casting method such as die, die, die casting, centrifugal casting, and the like.

Hereinafter, experimental examples to which the above-described technical ideas are applied will be described in order to facilitate understanding of the present invention. It should be understood, however, that the following examples are for the purpose of promoting understanding of the present invention and are not intended to limit the scope of the present invention.

Experimental Example 1

Experimental Example 1 was conducted to examine the possibility of increasing the amount of copper as an alloying element by ultrasonic treatment (UST; Ultrasonic treatment) as a basic test through an Al-Cu binary alloy. For this purpose, a binary alloy of the Al-Cu composition disclosed in Table 1 was used.

Composition (wt.%) Si Fe Cu Mn Mg Ti 0.089 0.08 3.93 0.001 0.004 0.041

In the experimental method, 1 kg of alloy was completely dissolved in electric resistance furnace, and ultrasonic treatment was performed using ultrasonic device. The ultrasonic treatment conditions were a frequency of about 19.0 kHz and a frequency of about 1 kW for 1 minute. During the ultrasonic treatment, the temperature of the molten metal was varied and tested. During the ultrasonic treatment, the temperature of the molten metal was reduced by about 30 ° C to 40 ° C. After the ultrasonic treatment, the molten metal was cast into a mold mold heated to 200 ° C.

FIG. 4A is a graph showing the electrical resistance of an aluminum alloy including copper when ultrasonic processing is performed according to some embodiments of the present invention, and FIG. 4B is a graph showing the electrical resistance of an aluminum alloy including copper when ultrasonic processing according to some embodiments of the present invention is performed. Graph showing changes in microhardness of an aluminum alloy including copper. The temperatures shown in Figs. 4A and 4B were based on the temperature at the time of injection into the mold after the ultrasonic treatment. For comparison, specimens without ultrasonic treatment were prepared by the same method with the same alloys, and melted at a melt temperature of 700 ℃ and then cast in the same mold.

Referring to FIG. 4A, when the ultrasonic treatment is performed, the electric resistance value is increased and the electric resistance value is increased as the temperature subjected to the ultrasonic treatment is increased as compared with the case where the ultrasonic treatment is not performed. This is due to the increase in the lattice strain of the base as the solubility of Cu increases in Al. On the other hand, it can be seen that as the ultrasonic treatment temperature is increased, the high capacity can be further increased.

Referring to FIG. 4B, it can be seen that the micro hardness value of the Al base is increased as well as the change of the electric resistance value, which means that the high capacity of Cu is increased.

Experimental Example 2

Experimental Example 2 is an experimental example in which one embodiment of the present invention is implemented. Specifically, it is applied to an A390 alloy (Al-17.95% Si-4.22% Cu) which is an over-process Al-Si alloy. In Experimental Example 2, a method of producing an Al-Si-based cast aluminum alloy can be performed, for example, along the line FGHI shown in FIG. 2B.

1. Manufacturing Method

The ultrasonic treated material was a commercially available A390 alloy (overbased alloy) containing 17.95 wt% Si and 4.2 wt% Cu. Specifically, the composition of the over-process alloy is shown in Table 2.

In the test method, 1 kg of A390 alloy was completely dissolved in an electric resistance furnace at a dissolution temperature of about 790 ° C., and ultrasonic treatment was performed using an ultrasonic device. As a condition of the ultrasonic treatment, about 1 kW of power was used at a frequency of about 19.0 kHz, and ultrasonic waves were applied to the melt for 1 minute. The temperature of the melt decreased slightly from 790 ℃ to 750 ℃ during the ultrasonic treatment. After the ultrasonic treatment, a molten metal was injected into a mold mold heated at 200 ° C and cast.

The method for producing an aluminum alloy for over-process Al-Si based casting according to Experimental Example 2 of the present invention is characterized in that the aluminum-silicon alloy containing over-processing aluminum-silicon alloy A first step of providing a molten metal; A second step of performing ultrasonic processing on the aluminum-silicon alloy melt; And a third step of solidifying the ultrasonic wave-treated aluminum-silicon alloy melt. These steps can be performed, for example, along the line F-G-H-I shown in FIG. 2B, which will be described below.

Referring to FIGS. 2A and 2B, when the temperature of the molten aluminum-silicon alloy is gradually cooled at point F and reaches the point G, primary silicon is first crystallized. Subsequently, the proportion of the superfine silicon gradually increases and the proportion of the molten metal gradually decreases from the point G to the point H, that is, to the process temperature (for example, 577 ° C. shown in the drawing). The composition of the molten metal from point G to point H follows the line G-E. When the molten aluminum alloy reaches point H (process temperature), eutectic reation occurs, and in the molten liquid remaining, the α-Al solid solution in which silicon is dissolved in aluminum and pure silicon are simultaneously extracted. Of course, the pure silicon may have a solid-solution form depending on the atmosphere of the molten metal and alloying elements (for example, magnesium, copper, and iron) which are further added to the molten metal. Herein, the pure silicon can be understood as eutectic Si. The rate of pure silicon increases gradually while cooling from point H to point I gradually increases, and the proportion of the [alpha] -Al solid solution, in which silicon is dissolved in aluminum, becomes smaller and smaller.

In Experimental Example 2, the second step of performing the ultrasonic treatment on the aluminum alloy melt was performed in a region where the melt was present. For example, the ultrasonic treatment was performed only until the first crystallization of the superfine silicon was performed in the molten metal (F-G section).

However, in a modified embodiment, the ultrasonic treatment may be performed until the molten metal reaches the process temperature (F-G-H period). In another modified embodiment, the ultrasonic treatment may be performed from the time when the superfine silicon is first crystallized in the molten metal until the process silicon appears in the molten metal (G-H period).

The third step of solidifying the aluminum alloy melt subjected to the ultrasonic treatment may include an H-I section and an aluminum-silicon cast alloy composed of a process structure surrounding the superfine silicon. The process structure is a structure in which? -Al solid solution in which silicon is dissolved in aluminum and pure silicon are simultaneously crystallized and grown.

The inventor of the present invention has confirmed that ultrafine silicon, which is realized in the cast alloy, can be finer by performing the ultrasonic treatment. When the super-fine silicon is coarsened, the aluminum-silicon cast alloy is embrittled and various problems that are very weak at grain boundaries occur. By performing the ultrasonic treatment, the super-fine silicon can be effectively refined.

On the other hand, for comparison, the same alloy was prepared by a conventional method without ultrasonic treatment. Specifically, 5 kg of an alloy having the same composition was dissolved in an electric resistance furnace at 720 占 폚 to remove hydrogen gas in the molten metal, and degassed for 15 minutes after the degassing treatment, and then injected into the mold mold.

 2. Characterization

(1) Heat treatment

First, heat treatment as shown in Table 3 was carried out on castings that were cast by the above-described manufacturing method.

Heat treatment Heat treatment condition F  As cast condition T6 Solution treatment 495 ° C / 8hrs → water quenching (to 60-80 ° C) →
Aging Treatment 175 ° C / 8hrs T7 Solution treatment 495 ° C / 8hrs → water quenching (to 60-80 ° C) →
Aging Treatment 230 ° C / 4hrs

Referring to FIG. 3 (a), as-cast is shown in which the cast aluminum alloy is formed by solidifying the aluminum alloy melt subjected to the ultrasonic treatment. The green casting may be referred to as an as-cast casting as it is without additional machining or heat treatment, and may be a casting that is cast by cooling along the HI line in FIG. 2B . Copper or the like added to the molten aluminum-silicon alloy may be dissolved in the aluminum matrix 320 in the above-described raw castings to exhibit the effect of solid solution strengthening, thereby contributing to the improvement of the strength. Silicon, copper, and the like added to the alloy melt react with each other with aluminum and exist in various forms of the secondary phase 330 in the raw casting, thereby exhibiting the effect of strengthening dispersion and contributing to the improvement of strength.

The solid solution strengthening is the action of another metal dissolved in a certain metal. The addition of solute atoms as a result of the interaction of the solute atoms with the displacement of the dislocations increases the yield strength of the crystalline material. The solid solution is a substituted solid solution and an interstitial solid solution. In the substituted solid solution, the size of the solvent atom and the solute atom is approximately the same, and the solute atom occupies the lattice point of the crystal lattice. Due to the different size of the solvent and solute atoms, the rule of the crystal lattice is disturbed, and the potential can not easily pass through this distorted lattice. In order for the potential to move again, a higher stress or temperature is required. In interstitial solid solutions, solute atoms are much smaller than solvent atoms and solute atoms occupy the interstitial positions of the solvent lattice. Interstitial atoms interfere with the movement of dislocations, and larger stresses and thermal energies are required for dislocations to move.

The dispersion strengthening means that the alloy is strengthened by the finely dispersed secondary phase particles in a soft matrix. In general, the metal can be effectively strengthened by the insoluble secondary phase finely dispersed in the matrix. At this time, precipitation hardening and dispersion strengthening can be distinguished depending on the method by which the dispersed secondary phase is introduced. Precipitation hardening is a strengthening phenomenon in the case where the secondary phase is formed by precipitation from a supersaturated solid solution. The dispersion strengthening is a phenomenon in which the secondary phase is formed by a process other than precipitation from a solid solution (for example, a powder metallurgy method or an internal oxidation method) It is a strengthening phenomenon. In order for precipitation hardening to occur, there is a difference in the degree of solubility depending on the temperature.

In order to maximize the precipitation hardening effect, it is necessary to increase the amount of the aluminum-silicon cast alloy in order to maximize the effect of precipitation hardening since the over-process aluminum-silicon cast alloy containing copper is most effectively known to increase the strength by precipitation hardening need. The present inventors have found that by applying ultrasonic waves to a molten aluminum-silicon melt containing copper, a copper element can be incorporated in an aluminum base of an aluminum-silicon cast alloy at a high temperature even at a high temperature, and the precipitation hardening effect can be improved by the subsequent heat treatment Respectively.

In order to strengthen the alloy by precipitation hardening, solid solution treatment should be performed first. 3 (a) and 3 (b), after the alloy is heated to a temperature at which the alloying elements can be melted into the matrix, the alloy is maintained for a certain period of time and then cooled to a low temperature at which alloying elements may be in a supersaturated state The quenching is the solution treatment. These solid solutions are metastable at low temperatures. Referring to Figures 3 (b) and 3 (c), the second part of the precipitation hardening process is an aging treatment. A phenomenon in which a precipitation phase 340 is generated and hardness (strength) is increased during the aging process is called age hardening or precipitation hardening. The age hardening is achieved by the case of the natural aging in which the precipitation phase 340 for strengthening the alloy is generated at room temperature and the case of artificial aging in which the precipitation phase 340 is generated by heating to a temperature higher than room temperature in order to shorten the aging time .

(2) Tensile test results

Table 4 shows averages of results obtained by performing tensile tests three times or more under each condition after the heat treatment described above.

First, analysis of the tensile test results in a heat-treated F (as-cast) state showed that the tensile strength was 194 MPa in normal casting but the tensile strength was 277 MPa after ultrasonic treatment.

On the other hand, the effect of precipitation hardening after heat treatment was also increased with increase of Cu content in Al in cast state. As a result, tensile properties were improved even under T6 and T7 conditions. Specifically, the tensile strength increased by 25 to 43% under all heat treatment conditions compared with the conventional method in the ultrasonic treatment.

(3) Fatigue test result

The specimens subjected to the T6 heat treatment described above were subjected to a high temperature cyclic fatigue test at room temperature. 5 is a graph showing high cyclic fatigue characteristics according to the presence or absence of ultrasonic treatment in an Al-Si-based cast aluminum alloy according to an embodiment of the present invention. Referring to FIG. 5, it can be seen that the fatigue of the alloy (□) without the ultrasonic treatment is 105 MPa, but the fatigue of the alloy (1) by the ultrasonic treatment is improved to 135 MPa.

3. Microstructural characterization

(1) Change in initial Si and process Si size

FIG. 6A is a micrograph of the microstructure of the A390 alloy not subjected to the ultrasonic treatment described above, FIG. 6B is a microscopic microstructure of the A390 alloy subjected to the ultrasonic treatment described above, and FIG. As a result, it can be seen that the size of the primary Si decreases and the distribution becomes uniform. On the other hand, the size of process Si did not decrease but increased somewhat. Table 5 shows the results of measuring the size with an image particle size analyzer.

Psalter Precision Si size (탆) Process Si Size (㎛) Normal casting method
(Comparative Example) 45.3 4.49 Ultrasonic treatment
(Invention) 19.9 4.74

(3) Analysis of the age-

The aged precipitates precipitated during the aging heat treatment of the A390 alloy were analyzed by TEM (see FIG. 7). The main aging precipitate was? "(CuAl ₂ ), and it was confirmed that the type of aged precipitates did not change with or without ultrasonic treatment.

(4) Analysis of lattice constant

Table 6 shows the results of measurement of the lattice constant of Al in the A390 alloy by X-ray diffraction analysis. It can be seen that the lattice constants are slightly different depending on the presence or absence of the ultrasonic treatment. Cu has a smaller atomic radius than Al, and the lattice constant becomes smaller as the amount of Cu contained in the Al increases. In casting or solution-treated state, the lattice constant of ultrasonic treated specimen is small. From this result, it can be predicted that the high capacity of Cu in ultrasonic treated specimen is large. In addition, the solubilization of specimen in cast state increases the lattice constant of both specimens because the amount of Cu increases. On the other hand, when the aging treatment is performed, the supersaturated Cu is precipitated as " (CuAl ₂ ) as shown in FIG. 7, and the lattice constant increases again. This effect can be seen in the ultrasonic treated specimens.

Psalter Casting state (탆) Solution Treatment (㎛) Aging treatment (T6) (占 퐉) Normal casting method
(Comparative Example) 4.0613 4.0578 4.0565 Ultrasonic treatment
(Invention) 4.0518 4.0471 4.0642

(6) Summary of results

From the results of the microstructure analysis, it is understood that the improvement of the properties (increase in strength) by the ultrasonic treatment is mainly due to the addition of Cu, which is mainly attributed to enhancement of Cu solubility and precipitation hardening during heat treatment.

Experimental Example 3

Experimental Example 3 was an experiment in which another embodiment of the present invention was implemented. Specifically, it was applied to a process Al-Si alloy (Al-12.3 wt% Si). In Experimental Example 3, a method of manufacturing an Al-Si-based cast aluminum alloy can be performed, for example, along the JEK line shown in FIG. 2B.

1. Manufacturing Method

The ultrasonic treated material used was a process Al-Si alloy containing 12.3 wt% Si and 3.3 wt% Cu. Specifically, the composition of the above-mentioned process alloy is shown in Table 7.

In the test method, 1 kg of the alloy was completely dissolved in an electric resistance furnace at a dissolution temperature of about 790 ° C., and ultrasonic treatment was performed using an ultrasonic device. As a condition of the ultrasonic treatment, about 1 kW of power was used at a frequency of about 19.0 kHz, and ultrasonic waves were applied to the melt for 1 minute. The temperature of the melt decreased slightly from 790 ℃ to 750 ℃ during the ultrasonic treatment. After the ultrasonic treatment, a molten metal was injected into a mold mold heated at 200 ° C and cast.

On the other hand, for comparison, the same alloy was prepared by a conventional method without ultrasonic treatment. Specifically, 5 kg of an alloy having the same composition was dissolved in an electric resistance furnace at 720 占 폚 to remove hydrogen gas in the molten metal, and degassed for 15 minutes after the degassing treatment, and then injected into the mold mold.

2. Characterization

(1) Heat treatment

First, heat treatment as shown in Table 8 was carried out on castings that were cast by the above-described manufacturing method.

Heat treatment Heat treatment condition T7 Solution treatment 490 ° C / 2hrs → water quenching (to 60-80 ° C) →
Aging Treatment 230 ° C / 5hrs

(2) Tensile test results

Table 9 shows the results obtained by averaging the results of the tensile test at least three times under each condition after the heat treatment described above. As a result of the tensile test, it was confirmed that the tensile strength increased by about 35% as compared with the conventional casting method in ultrasonic treatment.

Experimental Example 4

Experimental Example 4 is an experimental example of implementing another embodiment of the present invention, and specifically applied to a sub-process Al-Si alloy. In Experimental Example 4, a method of manufacturing an aluminum alloy for Al-Si-based casting can be performed along the LMNO line shown in FIG. 2B, for example.

1. Manufacturing Method

The ultrasonic treated material was a commercially available A356 alloy containing 7.18 wt% Si (substantially no Cu added), an alloy containing 0.7 wt% Cu added to A356 alloy, and an alloy containing 1.8 wt% Cu alloys were used for comparison. Specifically, the composition of the sub-alloy is shown in Table 10. < tb > < TABLE >

In the experimental method, 1 kg of the alloy was completely dissolved in an electric resistance furnace at a dissolving temperature of about 750 ° C., and ultrasonic treatment was performed using an ultrasonic device.

 As a condition of the ultrasonic treatment, about 1 kW of power was used at a frequency of about 19.0 kHz, and ultrasonic waves were applied to the melt for 1 minute. The temperature of the melt decreased slightly from 750 ℃ to 710 ℃ during the ultrasonic treatment. After the ultrasonic treatment, a molten metal was injected into a mold mold heated at 200 ° C and cast.

On the other hand, for comparison, the same alloy was prepared by a conventional method without ultrasonic treatment. Specifically, 5 kg of an alloy having the same composition was dissolved in an electric resistance furnace at 720 占 폚 to remove hydrogen gas in the molten metal, and degassed for 15 minutes after the degassing treatment, and then injected into the mold mold.

2. Characterization

(1) Heat treatment

First, heat treatment as shown in Table 11 was carried out on castings that were cast by the above-described manufacturing method.

Heat treatment Heat treatment condition F As cast condition

(2) Tensile test results

Table 12 shows the results obtained by averaging the tensile test results at three or more times under each condition after the above-described heat treatment.

Psalter Properties A356 (no Cu) A356 + 0.7% Cu A356 + 1.9% Cu Normal casting method
(Comparative Example) Tensile Strength (MPa)
Elongation (%) 165.5
5.5 195.3
3.0 224.8
3.9 Ultrasonic treatment
(Invention) Tensile Strength (MPa)
Elongation (%) 186.0
2.5 228.0
2.2 269.3
3.9

Specifically, the tensile strength of the A356 alloy to which no copper was added was increased by about 12% by 20.5 MPa compared to the tensile strength when the ultrasonic treatment was not performed, and when the copper was added by 0.7 wt% The tensile strength of ultrasonic treated A356 alloy increased by 16.7% by 32.7MPa compared to the tensile strength without ultrasonic treatment. The A356 alloy containing 1.9 wt% of copper showed a tensile strength The strength increased about 20.0% by the size of 44.5MPa than the tensile strength without ultrasonic treatment. That is, the tensile properties of the alloys after ultrasonic treatment were improved after the as-cast tensile test, and the increase in the tensile strength increased with increasing copper content.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (12)

As a method for producing an Al-Si-based cast aluminum alloy,
Providing an aluminum alloy melt containing aluminum (Al) and silicon (Si) and further comprising copper (Cu);
Applying vibration energy to the aluminum alloy melt; And
Coagulating the aluminum alloy melt to which the vibration energy is applied;
Wherein the Al-Si-based casting aluminum alloy is produced by a method comprising the steps of: The method according to claim 1,
Providing an aluminum alloy melt containing aluminum and silicon and further comprising copper;
Providing an aluminum alloy melt comprising silicon and a content of silicon capable of forming a sub-process composition, further comprising copper;
Wherein the Al-Si-based casting aluminum alloy is produced by a method comprising the steps of: The method according to claim 1,
Providing an aluminum alloy melt containing aluminum and silicon and further comprising copper;
Providing an aluminum alloy melt comprising silicon and a content of silicon capable of forming a process composition and further comprising copper;
Wherein the Al-Si-based casting aluminum alloy is produced by a method comprising the steps of: The method according to claim 1,
Providing an aluminum alloy melt containing aluminum and silicon and further comprising copper;
Providing an aluminum alloy melt comprising silicon and a content of silicon capable of forming an overbased composition with said aluminum, further comprising copper;
Wherein the Al-Si-based casting aluminum alloy is produced by a method comprising the steps of: The method according to claim 1,
Coagulating the aluminum alloy melt to which the vibration energy is applied; And then performing a solution treatment and aging-curing the Al-Si-based casting aluminum alloy. 6. The method of claim 5,
Performing the solution treatment process and aging curing;
And precipitating and curing the precipitate by precipitation containing copper formed in the aluminum matrix of the Al-Si system casting aluminum alloy. The method according to claim 1,
Applying vibration energy to the aluminum alloy melt;
Applying ultrasonic waves or pulses to the aluminum alloy melt;
Wherein the Al-Si-based casting aluminum alloy is produced by a method comprising the steps of: The method according to claim 1,
Wherein the silicon constitutes 1.65% to 30% by weight of the Al-Si-based casting aluminum alloy. The method according to claim 1,
Wherein the amount of copper contained in the Al-Si-based casting aluminum alloy is 0.5 wt% to 15 wt%. The method according to claim 1,
Wherein the aluminum alloy molten metal further comprises at least one selected from the group consisting of magnesium, zinc, manganese, chromium, nickel, titanium, vanadium, zirconium, iron, tin, cobalt and lithium. ≪ / RTI > The method according to claim 1,
Wherein the aluminum alloy melt further comprises ceramic particles. An aluminum alloy for Al-Si-based casting formed by the manufacturing method according to any one of claims 1 to 11.

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