KR20150071797A - Method and apparatus for fabricating casting alloy - Google Patents

Abstract

The present invention relates to a method and an apparatus for fabricating casting alloy with enhanced solid solution hardening, precipitation hardening and/or tractive characteristics. The method comprises: forming molten metal of a metal in a melting furnace; collecting a part of molten metal of the metal accommodated in the melting furnace using a container having a smaller quantity than the melting furnace; applying vibration energy to the molten metal of the metal; and injecting the molten metal of the metal to which the vibration energy is applied to a mold and solidifying the molten metal.

Description

TECHNICAL FIELD The present invention relates to a casting alloy,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a cast alloy, and more particularly, to a method and apparatus for producing a cast alloy by applying vibration energy to a melt.

In the production of a cast alloy, attempts have been made to develop a technique for improving the mechanical properties by making the structure of the interior of the alloy finer. The mechanical properties can be improved by making various phases to be formed inside the cast alloy fine. Typically, an Al-Si-based casting aluminum alloy, which realizes an aluminum alloy containing silicon by a casting method, is excellent in casting composition 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 are still being conducted to further improve the mechanical properties including the tensile strength and the yield strength of the cast alloy. It is an object of the present invention to effectively provide a manufacturing method and apparatus capable of further increasing the strength of a cast alloy. However, these problems are exemplary and do not limit the scope of the present invention.

There is provided a process for producing a cast alloy comprising at least one metal according to one aspect of the present invention. The method for producing a cast alloy includes the steps of forming a molten metal of the metal in a melting furnace, collecting a part of the molten metal contained in the molten metal in a container having a smaller capacity than the melting furnace, Applying a vibration energy to the mold and injecting the molten metal of the metal to which the vibration energy is applied, and solidifying the mold.

In the method of manufacturing the cast alloy, the step of applying the vibration energy to the molten metal contained in the small container may include applying ultrasonic waves or pulses to the molten metal contained in the small container.

In the process for producing a cast alloy, the metal may include an aluminum alloy, for example, an aluminum alloy for Al-Si casting. The silicon (Si) may have an amount capable of forming an over-processing composition, a process composition or a sub-process composition with the aluminum (Al). For example, among the aluminum alloy for Al- ) May constitute 1.65% to 30% by weight.

In the method for producing a cast alloy, the metal may include an Al-Si-based casting aluminum alloy further containing copper (Cu).

In the process for producing the cast alloy, the mold may include a mold for die, mold or mold for die casting.

A cast alloy according to another aspect of the present invention is provided. The cast alloy is implemented by the above-described manufacturing method.

An apparatus for producing a cast alloy according to another aspect of the present invention is provided. The apparatus for producing a cast alloy is an apparatus for producing a cast alloy containing at least one or more metals, the apparatus being capable of collecting and accommodating a part of the molten metal contained in the melting furnace, the capacity being smaller than that of the melting furnace; An ultrasonic device capable of applying vibration energy to the molten metal contained in the container; And a controller for controlling the movement of the container so as to collect the molten metal of the metal from the melting furnace and inject the molten metal into the mold from the container.

According to the embodiments of the present invention as described above, it is possible to provide a cast alloy improved in solid solution hardening, precipitation hardening and / or tensile properties by effectively applying vibration energy to the molten metal of the cast alloy. Of course, the scope of the present invention is not limited by these effects.

1 is a flow chart showing a method of manufacturing a cast alloy according to embodiments of the present invention.
Figures 2 to 5 are diagrams illustrating a method of making a cast alloy according to some embodiments of the present invention.
6 is a diagram illustrating an apparatus for producing a cast alloy and a manufacturing process therefor according to some embodiments of the present invention.
7A and 7B are diagrams illustrating a state diagram of aluminum-silicon for explaining a method of manufacturing an Al-Si-based cast aluminum alloy according to an embodiment of the present invention.
Fig. 8 is a diagram conceptually illustrating a structure for solution-treating and aging-curing in the process for producing an Al-Si-based cast aluminum alloy according to an embodiment of the present invention.
9A is a graph showing an electrical resistance of an aluminum alloy including copper when ultrasonic treatment is performed according to an embodiment of the present invention.
9B is a graph showing changes in microhardness of an aluminum alloy including copper when ultrasonic treatment according to an embodiment of the present invention is performed.
FIG. 10 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.
11A 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.
11B is an optical microscope photograph showing the microstructure of an Al-Si-based cast aluminum alloy according to an embodiment of the present invention.
12 is a photograph of an aged precipitate of an Al-Si-based cast aluminum alloy according to an embodiment of the present invention.
13 is a graph showing the size of the superfine silicon according to the holding time after the ultrasonic treatment in the method of manufacturing the over-process aluminum-silicon cast alloy according to the 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 a cast alloy according to an embodiment of the present invention. FIG. 2 is a schematic view showing a method of manufacturing a cast alloy according to an embodiment of the present invention. Figure 3 illustrates a step of applying vibrational energy to a molten metal of a metal contained in a small vessel in a method of making a cast alloy according to an embodiment of the present invention FIGS. 4A and 4B are diagrams illustrating a step of injecting and coagulating a molten metal to which a vibration energy is applied, into a mold for die casting in the method of manufacturing a casting alloy according to an embodiment of the present invention. In a method of manufacturing a cast alloy according to an embodiment of the present invention, a step of injecting a molten metal of a metal to which vibration energy is applied into a mold and solidifying it The.

1 to 5, a method of manufacturing a cast alloy according to embodiments of the present invention is a method of manufacturing a cast alloy including at least one or more metals, wherein the molten metal (200) (S200) of extracting a part of the molten metal (200) contained in the melting furnace (120) from the melting furnace (120) A step S300 of applying the vibration energy to the molten metal 200 accommodated in the mold 50 and a step S400 or S500 of injecting the molten metal 200 having the applied vibration energy into the molds 50 and 60, .

In an embodiment of the present invention, ultrasonic waves or pulsed waves may be applied to apply vibration energy, but it is not limited thereto and any type of vibration energy may be applied.

2 and 3, a portion of the large-capacity metal melt 200 accommodated in the melting furnace 120 is collected and accommodated in a container 140 having a smaller capacity than the melting furnace 120. The container 140 is used to directly inject the molten metal 200 into the molds 50 and 60. The size, shape, and shape of the container 140 shown in the drawings are exemplary and the technical idea of the present invention is not limited thereby.

When vibrational energy such as ultrasonic waves or pulses is directly applied to the large-capacity molten metal 200 accommodated in the melting furnace 120, it may be difficult to uniformly apply the effect of applying the vibrational energy to the large-capacity molten metal 200. For example, when vibrational energy such as ultrasonic waves is directly applied to the molten metal 200 of a large capacity, the penetration depth of the ultrasonic waves is small, so that the effect of ultrasonic waves can not be sufficiently realized. To this end, a plurality of ultrasonic treatment apparatuses can be disposed on the sidewall of the melting furnace 120 that houses the large-capacity molten metal 200. However, in the course of passing through the material constituting the sidewall of the melting furnace 120, the ultrasonic waves are canceled The ultrasonic treatment effect applied to the molten metal 200 of large capacity may be insignificant. This is also the case when an ultrasonic device is installed on the outer wall of the molds 50 and 60.

The inventor has found that the vibration energy is not applied to the molten metal 200 of a large capacity accommodated in the melting furnace 120 in order to maximize the effect of the application of the vibration energy but also to the molten metal 200 contained in the small container 140 And a method of injecting the molten metal 200 to which the vibration energy is applied to the molds 50 and 60 after the vibration energy is applied. Such a method can be more effective for a mold casting method or a die casting method in which, for example, a large amount of molten metal is prepared and then a small amount of molten metal is injected into the mold by using, for example, a robot arm to produce a cast article. 2 to 5, the robot arm may be connected to one side of the container 140 to control the movement of the container 140. [

Specifically, the horn 155 connected to the ultrasonic device 150 can be inserted into the molten metal 200 accommodated in the small container 140 and the ultrasonic wave can be applied. The condition of the ultrasonic wave generated in the ultrasonic device 150 can be appropriately adjusted according to the capacity of the molten metal 200 accommodated in the small container 140 described above. For example, the ultrasonic wave may have a frequency in the range of 17 kHz to 23 kHz and an output in the range of 0.5 kW to 5 kW. However, the numerical ranges of the above-mentioned frequencies and outputs are exemplary and the technical idea of the present invention is not limited thereby.

A method of manufacturing a casting alloy according to an embodiment of the present invention is a method of manufacturing a casting alloy by precisely machining a casting shape by precisely machining a molten metal into a steel mold to obtain the same casting It can be applied to die casting, which is a casting method.

4A and 4B, after the vibration energy is applied to the molten metal 200 contained in the small container 140, the molten metal 200 can be injected from the container 140 into the die casting mold 50 . The die casting mold 50 includes a molding space 54 in which a molten metal 200 is injected to form a molded product and is connected to the molding space 54 for injecting the molten metal 200, There is provided a plunger 53 for pressing the molten metal 200 supplied to the sleeve 52 and causing the molten metal 200 to be injected into the molding space 54. The sleeve 52 is provided with a melt supply port 51 for receiving the melt 200 through the container 140 on the upper side. That is, the molten metal 200 supplied to the sleeve 52 is filled from the lower side of the sleeve 52. The molten metal 200 is supplied from the container 140 to the sleeve 52 with the plunger 53 retracted to the back of the mold 50 as shown in Fig. 4B, when the plunger 53 is moved forward, the molten metal 200 supplied to the sleeve 52 is pressurized by the plunger 53, so that the molding space 54 is closed, . The molten metal 200 is solidified in a state where the molten metal 200 is injected into the molding space 54, thereby molding the molded product.

Meanwhile, a method of manufacturing a cast alloy according to an embodiment of the present invention may be applied to sand casting.

5, after the vibration energy is applied to the molten metal 200 accommodated in the small container 140, the molten metal 200 can be injected from the container 140 into the mold 160. FIG. The molten metal 200 flows from the sprue 61 to the runner 62 and enters the portion forming the empty space of the shape through the entrance portion of the gate 64 (gate). The riser 63 is a small reservoir of liquid metal to be supplied when the cast shape is cooled and shrunk. The core 65 may be disposed in the mold to form a space, such as a hole in the cylinder. The closed mold casting is used in half of the cop 66 or drag 67 and is sealed with a flask 68. The mold breaks to remove the cast shape. The parting line is located where half of the two molds meet.

6 is a diagram illustrating an apparatus for producing a cast alloy and a manufacturing process therefor according to some embodiments of the present invention. Referring to Fig. 6, there is provided an apparatus 190 for producing a cast alloy according to another aspect of the present invention. The casting alloy manufacturing apparatus 190 is an apparatus for producing a cast alloy containing at least one metal. The casting alloy manufacturing apparatus 190 can collect and accommodate a part of the molten metal 200 contained in the melting furnace 120, A container 140 having a smaller capacity; An ultrasonic device 150 capable of applying vibration energy to the molten metal 200 contained in the container 140; And to control the movement of the container 140 so that the molten metal 200 is taken from the melting furnace 120 to the container 140 and the molten metal 200 is injected from the container 140 into the mold 70. [ And a control unit 110 for controlling the operation of the apparatus.

The control device 110 can control to collect the molten metal 200 from the melting furnace 120 to the container 140 by adjusting the angle of the container 140 or moving the container 140, The molten metal 200 can be controlled to be injected from the mold 140 into the mold 70. For example, the control device 110 may include a robot 110a configured to control the movement of the container 140. For example, The robot 110a may have a robot arm connected to one side of the container 140. On the other hand, the control device 110 may be fixed on the ground, but it may move without being fixed on the ground as required.

The ultrasonic device 150 may include a horn 155 disposed at one end of the horn 155. The horn 155 may be inserted into the molten metal 200 accommodated in the container 140 to apply ultrasonic waves. The condition of the ultrasonic wave generated in the ultrasonic device 150 can be appropriately adjusted according to the capacity of the molten metal 200 accommodated in the small container 140 described above. For example, the ultrasonic wave may have a frequency in the range of 17 kHz to 23 kHz and an output in the range of 0.5 kW to 5 kW. However, the numerical ranges of the above-mentioned frequencies and outputs are exemplary and the technical idea of the present invention is not limited thereby.

The mold 70 has a mold 70a including a molding space 70b therein. The mold 70 may include, for example, a mold for a die, a die for a mold or a mold for die casting, and specifically, a mold 50 for die casting.

The apparatus for producing a cast alloy according to still another aspect of the present invention may further include a melting furnace 120 and / or a mold 70 in addition to the above-described apparatus 190.

Hereinafter, a case where the above-described manufacturing method is specifically applied to an Al-Si-based cast aluminum alloy will be described as an example. However, the present invention is not limited to this, and it is obvious that the present invention can be applied to other metals or alloys capable of performing ultrasonic treatment for fineness treatment and strength improvement.

FIGS. 7A and 7B are diagrams illustrating a state diagram of aluminum-silicon for explaining a method of manufacturing an Al-Si-based cast aluminum alloy according to an embodiment of the present invention. Fig. 2 is a conceptual illustration of a solution-treating and aging-curing structure in a process for producing an Al-Si-based cast aluminum alloy according to the present invention.

A method of manufacturing an Al-Si-based casting aluminum alloy according to an embodiment of the present invention includes the steps of forming an aluminum alloy molten metal in a melting furnace including aluminum (Al) and silicon (Si) step; Collecting a part of the molten aluminum alloy contained in the melting furnace into a container having a smaller capacity than the melting furnace; Applying vibration energy to the aluminum alloy melt contained in the small vessel; And coagulating the aluminum alloy melt to which the vibration energy is applied. Further, a method of manufacturing an Al-Si-based casting aluminum alloy according to an embodiment of the present invention is characterized in that the as-cast as-cast formed by solidifying the aluminum alloy melt is subjected to a solution treatment ); And aging-curing the solution-processed raw castings.

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. 7A and Fig. 7B). [0051] 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 present inventors have found that when the alloy melt of the above composition is cast by applying vibration energy to the alloy melt of the above composition as compared with the case where the alloy melt of the above composition is cast by a conventional method without applying vibration energy, And the mechanical properties of the aluminum alloy for Al-Si-based casting were improved.

In addition, even when the material in the cast state is heat-treated (solubilization / aging treatment), the precipitation hardening effect is increased by the precipitate containing copper because the initial high capacity is high, and the mechanical properties of the aluminum alloy for Al- Respectively.

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, at least one selected from the group consisting of magnesium, zinc, manganese, chromium, nickel, titanium, vanadium, zirconium, iron, tin, cobalt and lithium may be further added to the molten Al-Si alloy.

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, ceramic particles such as SiC, Al ₂ O _3, and / or B ₄ C may be added to the molten Al-Si alloy.

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.

On the other hand, in the embodiments of the present invention, ultrasonic waves are applied to the molten metal of the cast alloy, and in order to help understand the effect of applying ultrasonic waves to the molten metal of the cast alloy, experiments using the above- Examples (Experimental Examples 1 to 4) will be described. In addition, an experimental example (Experiment Example 5) in which the above-described technical idea is applied to understand the holding time after the ultrasonic treatment in the manufacturing method of the over-process aluminum-silicon cast alloy will be described. 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.

9A 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, and FIG. 9B is a graph showing the electrical resistance of an aluminum alloy containing copper when ultrasonic treatment according to some embodiments of the present invention Graph showing changes in microhardness of an aluminum alloy including copper. The temperatures shown in Figs. 9A and 9B 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. 9A, when the ultrasonic wave treatment is performed, the electric resistance value increases and the electric resistance value increases as the temperature for the ultrasonic wave treatment increases, compared with the case where the ultrasonic wave 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. 9B, it can be seen that the microhardness 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. 7B.

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.

7A and 7B, when the temperature of the molten aluminum-silicon alloy is gradually cooled at point F and reaches the point G, the primary Si 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 the H point (process temperature), an eutectic reaction occurs, and in the liquid molten metal remaining, α-Al solid solution and pure silicon which are in the form of silicon dissolved in aluminum 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, the castings in the casting state by the above-described manufacturing method were subjected to the heat treatment as shown in Table 3.

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. 8 (a), an as-cast in a cast state formed by solidifying the aluminum alloy melt subjected to the ultrasonic treatment is shown. The raw casting may be referred to as an as-cast casting as it is without additional machining or heat treatment, and may be a casting which is cast by cooling along the HI line in FIG. 7B . 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. 8 (a) and 8 (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 heated to a low temperature at which the 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 8 (b) and 8 (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. FIG. 10 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. 10, the fatigue of the alloy (□) without the ultrasonic treatment is 105 MPa, but the fatigue of the alloy (1) subjected to the ultrasonic treatment is improved to 135 MPa.

3. Microstructural characterization

(1) Change in initial Si and process Si size

FIG. 11A is a microscopic image of the microstructure of the A390 alloy not subjected to the above-described ultrasonic treatment, FIG. 11B is a microscopic image of the microstructure of the A390 alloy subjected to the ultrasonic treatment described above, 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. The main aging precipitate was θ "(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 carried out, the supersaturated Cu is precipitated as "" (CuAl ₂ ) as shown in FIG. 12, 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 aluminum alloy for Al-Si-based casting can be performed, for example, along the JEK line shown in FIG. 7B.

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 producing an aluminum alloy for Al-Si-based casting can be performed along the LMNO line shown in FIG. 7B, 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 substantially added was increased by about 12% by 20.5 MPa compared with the tensile strength when the ultrasonic treatment was not performed, and when 0.7 wt% of copper was added 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.

Experimental Example 5

Experimental Example 5 measured the size of the superfine silicon according to the holding time after the ultrasonic treatment in the manufacturing method of the over-process aluminum-silicon cast alloy according to still another embodiment of the present invention. In the test method, 20 kg of the alloy was completely dissolved in an electric resistance furnace, and then the molten metal was collected into a small container capable of accommodating 1 kg of molten metal, and the molten metal was subjected to ultrasonic treatment in the small container.

13, an aluminum alloy melt in the range of 800 ° C. to 750 ° C. was subjected to ultrasonic treatment for 1 minute, and then the aluminum alloy melt was held for 1 minute, 4 minutes, 7 minutes, and 10 minutes, And the aluminum alloy melted in the range of 750 ° C to 700 ° C for 1 minute, followed by a holding time of 1 minute, 4 minutes, 7 minutes and 10 minutes, followed by solidification The size of the superfine silicon (A) in the A390 alloy appears. According to the results, it was confirmed that the size of the superfine silicon was finer than the case where the ultrasonic treatment was performed in the case of performing the ultrasonic treatment for about 1 minute. The effect of the ultrasonic wave treatment is that the retention time of the melt after the ultrasonic treatment It is confirmed that the ultrasonic treatment effect is stabilized until about 7 minutes and then the effect of ultrasonic treatment can be somewhat reduced. 1 to 5, the processing time for injecting the aluminum alloy melt 200 subjected to the ultrasonic treatment into the molds 50 and 60 is 10 minutes after the ultrasonic treatment is performed It can be expected that the effect of the ultrasound treatment of micronization of superfine silicon can be effectively realized.

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.

120: melting furnace 140: small vessel
150: Ultrasonic device 155: Horn of ultrasonic device
50: die casting mold 60: die casting mold
200: Molten aluminum alloy 300: Aluminum-silicon alloy

Claims (11)

A method of making a cast alloy comprising at least one or more metals,
Forming a molten metal of said metal in a melting furnace;
Collecting a part of the molten metal of the metal accommodated in the melting furnace into a container having a smaller capacity than the melting furnace;
Applying vibration energy to the molten metal contained in the small vessel; And
Injecting the molten metal of the metal to which the vibration energy is applied into a mold and solidifying the molten metal;
≪ / RTI > The method according to claim 1,
Applying vibrational energy to the molten metal contained in the small vessel;
And applying ultrasonic waves or pulses to the molten metal contained in the small vessel. The method according to claim 1,
Wherein the metal comprises an aluminum alloy. The method of claim 3,
Wherein the aluminum alloy comprises an Al-Si-based casting aluminum alloy. 5. The method of claim 4,
Wherein the silicon (Si) has a content capable of forming an over-process composition, a process composition or a sub-process composition with the aluminum (Al). 5. The method of claim 4,
Wherein the silicon (Si) constitutes 1.65 wt% to 30 wt% of the Al-Si-based cast aluminum alloy. The method of claim 3,
Wherein the aluminum alloy is an Al-Si-based casting aluminum alloy further comprising copper (Cu). The method according to claim 1,
Wherein the mold comprises a mold die, a mold mold or a mold for die casting. A cast alloy formed by the process according to any one of claims 1 to 8. An apparatus for producing a cast alloy comprising at least one or more metals,
A container capable of collecting and accommodating a part of the molten metal contained in the melting furnace and having a smaller capacity than the melting furnace;
An ultrasonic device capable of applying vibration energy to the molten metal contained in the container; And
A control device for controlling the movement of the container so that the molten metal can be taken from the melting furnace to the container and the molten metal can be injected into the mold from the container;
Wherein the casting alloy is a cast alloy. 11. The method of claim 10,
Wherein the mold comprises a mold die, a mold mold or a mold for die casting.

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