KR101273579B1 - Aluminum alloy extruded products and manufacturing method thereof - Google Patents

Abstract

Provided is an environmentally friendly aluminum alloy extruded material having excellent alloying properties and a method of manufacturing the same. According to the method for producing an aluminum alloy extruded material according to an aspect of the present invention, there is provided a magnesium mother alloy containing a calcium-based compound in the magnesium matrix. The magnesium master alloy is added to the molten aluminum. The molten metal is cast to prepare an aluminum alloy. The aluminum alloy is extruded.

Description

Aluminum alloy extruded materials and manufacturing method thereof

The present invention relates to an aluminum alloy and a method for producing the same, and more particularly, to an aluminum alloy extruded material and a method for producing the same.

In the current aluminum (Al) alloy, magnesium (Mg) is one of the major alloying elements. The addition of magnesium increases the strength of aluminum alloys, favors surface treatment and improves corrosion resistance. However, in the process of alloying magnesium in the aluminum molten metal, oxides or inclusions are mixed into the aluminum molten metal by the magnesium having high chemical oxidation property, which causes a problem of lowering the quality of the molten metal. In order to suppress the incorporation of oxides or inclusions due to the addition of magnesium, a method of applying a molten surface with a protective gas such as SF ₆ may be used when magnesium is added.

However, in the manufacturing process of aluminum alloys, it is difficult to completely protect magnesium, which is added on a large scale, with a protective gas. Furthermore, SF _{6, which} is used as a protective gas, is not only expensive, but also an environmental problem, and its use is increasingly regulated worldwide.

Accordingly, the present invention is to provide an aluminum alloy extruded material and a method of manufacturing the same using an aluminum alloy having excellent alloying properties while being environmentally friendly. These tasks are presented by way of example, and the scope of the present invention is not limited by these tasks.

According to one aspect of the present invention, there is provided a method for producing an aluminum alloy extruded material. Provided is a magnesium mother alloy comprising a calcium-based compound in a magnesium matrix. The magnesium master alloy is added to the molten aluminum. The molten metal is cast to prepare an aluminum alloy. The aluminum alloy is extruded.

The method of manufacturing the aluminum alloy extruded material may further include heat treating the aluminum alloy extruded material after extruding the aluminum alloy.

In the manufacturing method of the aluminum alloy extruded material, the calcium-based compound includes any one or more of the Mg-Ca compound, Al-Ca compound and Mg-Al-Ca compound, the Mg-Ca compound comprises Mg ₂ Ca The Al-Ca compound may include any one or more of Al ₂ Ca and Al ₄ Ca, and the Mg-Al-Ca compound may include (Mg, Al) ₂ Ca.

In the manufacturing method of the aluminum alloy extruded material, the magnesium master alloy may be prepared by adding a calcium-based additive to the molten metal of the base material as a base material of pure magnesium or magnesium alloy containing aluminum.

In the method of manufacturing the aluminum alloy extruded material, the calcium compound may be formed by dispersing and adding a calcium-based additive to the surface of the upper portion of the magnesium molten metal, and then exhausting at least a portion of the calcium-based additive in the magnesium molten metal. have.

Furthermore, the calcium-based compound may be formed by exhausting in the magnesium molten metal so that the calcium-based additive does not substantially remain in the magnesium mother alloy.

In the manufacturing method of the aluminum alloy extruded material, in order to exhaust the added calcium-based additive may be stirred to the upper layer of the molten magnesium. In this case, the stirring may be performed at an upper layer of 20% or less of the total depth of the magnesium molten metal.

The calcium-based additive may include any one or more of calcium oxide (CaO), calcium cyanide (CaCN ₂ ) and calcium carbide (CaC ₂ ). Further, at least a part of the calcium-based additive is exhausted in the molten metal of the base material, the calcium-based compound may be produced by the reaction of the calcium supplied from the calcium-based additives with magnesium or aluminum of the base material.

In the manufacturing method of the aluminum alloy extruded material, the magnesium master alloy is 0.0001 to 30 parts by weight based on 100 parts by weight of aluminum, the calcium-based additive is added in the range of 0.0001 to 30 parts by weight based on 100 parts by weight of the base material. Can be.

According to another aspect of the present invention, an aluminum alloy extruded material is prepared by extruding a cast aluminum alloy by adding a magnesium mother alloy in which a calcium-based compound is distributed in a magnesium matrix to 0.0001 to 30 parts by weight based on 100 parts by weight of aluminum. The aluminum base may include the calcium compound.

In the aluminum alloy extruded material, the aluminum base may be dissolved in magnesium in the range of 0.1 to 15% by weight.

The aluminum alloy extruded material may further include iron (Fe) in an amount of 1.0 wt% or less (greater than 0) in the aluminum base.

An aluminum alloy extruded material according to another aspect of the present invention includes an aluminum base and a calcium-based compound present in the aluminum base, and has a higher strength than an aluminum alloy extruded material produced under the same conditions without containing the calcium-based compound. Can be large.

The aluminum alloy extruded material may have a smaller average size of crystal grains than the aluminum alloy extruded material manufactured under the same conditions without having the calcium-based compound.

The aluminum alloy extruded material may have a greater tensile strength and a greater or equal elongation than an aluminum alloy extruded material prepared under the same conditions without having the calcium-based compound.

According to the method of manufacturing an aluminum alloy extruded material according to an embodiment of the present invention, as magnesium is added in the form of a mother alloy containing a calcium-based compound, a protective gas such as SF ₆ which is conventionally used to prevent oxidation of the aluminum molten metal. Extruded material can be stably produced even if the amount of is significantly reduced or not used. In addition, as the content of magnesium in the aluminum can be stably increased, an aluminum alloy extruded material having a high composition of magnesium can be manufactured.

In addition, the aluminum alloy extruded material according to an embodiment of the present invention, as the calcium-based compound added with the addition of the magnesium mother alloy is dispersed in the aluminum matrix, causing a dispersion strengthening effect and a grain refining effect, thereby causing mechanical properties of the aluminum alloy extruded material. Can be significantly improved.

The effects of the present invention are not limited to those mentioned above, and other effects, which are not mentioned above, will be clearly understood by those skilled in the art from the following description.

1 is a flowchart showing one embodiment of a method for producing a magnesium master alloy to be added to an aluminum molten metal in the production of an aluminum alloy according to the present invention.
2 is a result of analyzing the microstructure and components of the magnesium mother alloy.
Figure 3 is a flow chart showing an embodiment of the aluminum alloy manufacturing method according to the present invention.
Figures 4a and 4b are the results of observing the molten surface of the aluminum alloy with the addition of the mother alloy prepared by adding calcium oxide (CaO) and the pure magnesium, respectively according to an embodiment of the present invention.
5A and 5B show the results of observing the casting material surfaces of aluminum alloys added with a mother alloy prepared by adding calcium oxide (CaO) and aluminum alloys added with pure magnesium, respectively, according to one embodiment of the present invention.
6A and 6B illustrate the results of analyzing the components of an aluminum alloy added with a magnesium mother alloy added with calcium oxide (CaO) and an aluminum alloy added with pure magnesium, respectively, according to an embodiment of the present invention.
Figure 7a is a result of observing the structure of the aluminum alloy to which the magnesium mother alloy to which calcium oxide (CaO) is added in accordance with an embodiment of the present invention with EPMA, Figure 7b to 7e as a component mapping result using EPMA, respectively A mapping result of aluminum, calcium, magnesium and oxygen is shown.
8 to 10 is a photograph showing a comparison between the microstructure of Experimental Examples 2 to 4 and Comparative Examples 2 to 4 of Table 5.
FIG. 11 is a schematic diagram illustrating a process of decomposing calcium oxide in an upper layer of magnesium molten metal when calcium oxide is added to the molten magnesium.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the intention is not to limit the invention to the precise form disclosed and that the invention is not limited thereto. It is provided to let you know.

According to the present invention, an aluminum alloy is prepared by preparing a mother alloy to which a predetermined additive is added and then adding the mother alloy to aluminum. Subsequently, this aluminum alloy can be extruded and an aluminum alloy extruded material can be manufactured. In addition, the aluminum alloy extruded material may be subjected to a suitable heat treatment process.

Here, the mother alloy may use pure magnesium or magnesium alloy as a base material, all referred to as magnesium master alloy. Pure magnesium is a state in which no alloying element is intentionally added, and is defined as a practical meaning including impurities inevitably added during the manufacture of magnesium.

In addition, the magnesium alloy is an alloy prepared by intentionally adding another alloy element to magnesium, it may include aluminum as the alloy element. A magnesium alloy containing aluminum as the alloying element may be referred to as a magnesium-aluminum alloy. In this case, the magnesium-aluminum alloy may include not only aluminum as an alloy element but also other alloy elements other than aluminum.

1 is a flowchart showing an embodiment of a method for producing a magnesium master alloy. Referring to FIG. 1, the method for producing a magnesium mother alloy includes a molten magnesium forming step (S1), an additive adding step (S2), a stirring and holding step (S3), and a casting step (S4).

In the magnesium melt forming step S1, pure magnesium or a magnesium alloy is placed in a crucible and heated to form a magnesium melt. At this time, the heating temperature may be in the range of 400 to 800 ℃ as an example. In the case of pure magnesium, the molten metal is formed at a temperature of 600 ° C. or higher. However, in the case of the magnesium alloy, the molten metal may be formed at a temperature of 600 ° C. or lower and higher than 400 ° C. due to the lowering of the melting point. If the temperature is less than 400 ° C, the magnesium melt is difficult to form, and if the temperature exceeds 800 ° C, the magnesium melt may sublimate or may ignite.

The magnesium alloys used in the molten magnesium forming step (S1) are AZ91D, AM20, AM30, AM50, AM60, AZ31, AS141, AS131, AS121X, AE42, AE44, AX51, AX52, AJ50X, AJ52X, AJ62X, MRI153, MRI230, AM -May be any one selected from HP2, magnesium-Al, magnesium-Al-Re, magnesium-Al-Sn, magnesium-Zn-Sn, magnesium-Si, magnesium-Zn-Y and equivalents thereof. It is not intended to limit the invention. Any magnesium alloy normally used in the industry can be used.

On the other hand, in order to prevent ignition of the magnesium molten metal, a small amount of protective gas may be additionally provided. As the protective gas, ordinary SF6, SO2, CO2, HFC-134a, Novec ™ 612, an inert gas or its equivalent, or a mixed gas thereof is used and the ignition of the magnesium melt can be suppressed.

In the next step of adding the calcium-based additive (S2), the calcium-based additive is added to the molten magnesium. In this case, the calcium-based additive to be added may include any one or more of calcium oxide (CaO), calcium cyanide (CaCN ₂ ) and calcium carbide (CaC ₂ ). The oxidation resistance in the molten magnesium may be improved by the calcium-based additive, and thus, the amount of protective gas required for dissolving magnesium may be significantly reduced or not used. Therefore, the production of the magnesium master alloy according to the embodiment of the present invention can solve the problems caused by the use of the protective gas such as SF ₆ which is the object of regulation for environmental reasons.

In addition, due to the improved oxidation resistance of the molten magnesium, the ignition resistance is increased to suppress the incorporation of oxides or other inclusions into the molten magnesium. Therefore, the cleanliness of the molten metal is drastically improved, and the improvement of the cleaning efficiency of the molten metal improves the mechanical characteristics of the magnesium alloy cast therefrom.

At least some of the calcium-based additives may be exhausted in the molten magnesium. Under moderate conditions, substantially all of the calcium-based additives may be exhausted in the magnesium molten metal. For example, the calcium-based additive may be reduced in the molten magnesium and decomposed into calcium. As an example, calcium oxide, a calcium-based additive, may be decomposed into calcium and oxygen. In this case, the decomposed oxygen may be discharged from the magnesium molten metal to the atmosphere in a gaseous state or may float on the molten metal as a dross or sludge.

Meanwhile, calcium decomposed from calcium oxide may form a compound through various reactions in the molten metal. Such compounds may be intermetallic compounds formed by chemical reactions between metals. The reduced calcium can then react with other elements in the matrix, for example magnesium and / or aluminum, to form calcium-based compounds.

Therefore, the calcium-based additive is a source of calcium used to form the calcium-based compound formed in the magnesium mother alloy and is an additive element added to the base metal molten metal during the production of the mother alloy, and the calcium-based compound is supplied from the calcium-based additive. Calcium is a newly produced compound by reacting with other elements in the base metal.

Although calcium has a solid solubility for magnesium, it has been found that, as in the present invention, only a portion of the calcium reduced from the calcium-based additive in the molten magnesium is dissolved in the magnesium base, and most of it forms a calcium-based compound.

When the base material of the magnesium mother alloy is pure magnesium, the calcium-based compound that can be produced may be an Mg-Ca compound, and for example, Mg 2 Ca. In addition, when the base material of the magnesium master alloy is a magnesium alloy, for example, a magnesium-aluminum alloy, the calcium compound that can be produced may include any one or more of an Mg-Ca compound, an Al-Ca compound, and an Mg-Al-Ca compound. have. For example, the Mg-Ca compound may be Mg ₂ Ca, the Al-Ca compound may include any one or more of Al ₂ Ca and Al ₄ Ca, and the Mg-Al-Ca compound is (Mg, Al) ₂ Ca Can be.

The decomposition and reaction of the calcium-based additives may be further activated through stirring, which will be described later in more detail in the next step of stirring and maintaining step (S3).

Calcium-based additives are advantageous as the surface area is larger for improving reactivity, and therefore, it is advantageous to be added in powder form. However, the present invention is not limited to this, and it is also possible to put the powder in the form of a pellet or a lump in which the powder is agglomerated in order to prevent the powder from scattering.

The calcium-based additive may have a size of 0.1 to 500 μm, more strictly 0.1 to 200 μm. If the size of the calcium-based additive is less than 0.1㎛ is too fine to be scattered by the sublimated magnesium hot air is difficult to enter the crucible. In addition, as the aggregates form aggregates, they do not easily mix with the molten metal in the liquid phase. Such agglomerates are undesirable from the viewpoint of reducing the surface area for the reaction. When the size of the calcium-based additive exceeds 500㎛ the surface area for the reaction is reduced, furthermore, the calcium-based additive may not react with the magnesium molten metal.

Calcium-based additives may be added 0.001 to 30wt%, more strictly 0.01 to 15wt% may be added. If the total amount of the calcium-based additive is less than 0.001wt%, the improvement of the mechanical properties of the magnesium alloy is insignificant or hardly occurs. In addition, when the total amount of the calcium-based additives exceeds 30wt%, the original magnesium may not appear.

Calcium-based additives may be added to the molten magnesium at the same time or at a time difference from each other. In addition, the required amount can be inputted at a time or divided into a proper amount, and can be inputted into a plurality of steps with a certain time difference. When the calcium-based additive to be added is a powder having fine particles, it is possible to accelerate the reaction of the calcium-based additive while reducing the agglomeration potential of the powder by adding a plurality of steps with time difference.

In order to accelerate the decomposition and reaction of the calcium-based additives, stirring may be performed in the stirring and maintaining step (S3) of the molten magnesium. The stirring may start at the same time as the addition of the calcium-based additive or after the added calcium-based additive is heated to a certain temperature in the molten metal.

In the case of ordinary metal alloying, the molten metal and the alloying element are agitated agitated so that the reaction takes place inside the molten metal through convection or stirring. However, in this embodiment, when inducing an active reaction of the calcium-based additives, the reaction of the calcium-based additives is rather inefficient, and the frequency of remaining in the final melt in the undissolved state increases. If the calcium-based additive remains in the final molten metal, it is incorporated in the cast magnesium alloy as it is, which may deteriorate the mechanical properties of the magnesium alloy.

FIG. 11 is a diagram illustrating a process of decomposing calcium oxide in an upper layer of magnesium molten metal when calcium oxide is added to the molten magnesium by way of example. Referring to FIG. 11, calcium oxide is decomposed into oxygen and calcium in the upper part of the molten magnesium. At this time, the decomposed oxygen is discharged as the gas (O ₂ ) out of the magnesium molten metal or floated on the magnesium molten metal as dross or sludge. Meanwhile, the decomposed calcium reacts with other elements in the molten metal to form various compounds.

Therefore, in this embodiment, it is important to form a reaction environment so that the calcium-based additive reacts on the surface of the molten magnesium rather than being mixed into the magnesium molten magnesium. To this end, it is preferable to stir the upper portion of the magnesium melt so that the added calcium-based additive remains on the surface of the melt for as long as possible and is exposed to the atmosphere.

5 wt% CaO addition 10wt% CaO addition 15wt% CaO addition CaO Remaining in Alloy No agitation 4.5 wt% CaO 8.7 wt% CaO 13.5 wt% CaO Stirring in the molten metal 1.2 wt% CaO 3.1 wt% CaO 5.8 wt% CaO Melt upper layer stirring (invention) 0.001 wt% CaO 0.002 wt% CaO 0.005 wt% CaO

Table 1 shows the results of measuring the residual amount of calcium oxide according to the stirring method when calcium oxide was added to the AM60B magnesium molten metal. The size of added calcium oxide was 70 ㎛ and 5, 10 and 15 wt% of calcium oxide was added. As the stirring method, a method in which the upper portion of the magnesium melt was stirred, the inner stirring and the stirring were not performed was selected. From Table 1, it can be seen that, when stirring the magnesium upper part, most of the added calcium oxide is reduced to calcium, unlike the other cases.

Such agitation is preferably carried out in an upper portion of about 20% of the total depth of the molten metal from the surface of the molten magnesium, preferably in the upper portion of about 10% of the entire depth of the molten metal. At a depth of 20% or more, decomposition of the calcium-based additives on the surface becomes difficult to occur.

At this time, the time for stirring may vary depending on the temperature of the molten metal and the state of the powder to be added, and may be used up so that the added calcium-based additive may not remain at least partially or substantially in the magnesium mother alloy. Exhaustion here means that the decomposition of the calcium-based additives is substantially completed. Therefore, the calcium-based additive to be added is preferably stirred until it is exhausted by sufficient reaction in the molten magnesium. However, it is effective in the case where it is not partially reacted and remains in the alloy and does not significantly affect the physical properties.

Such agitation can further promote the decomposition of calcium-based additives in the magnesium molten metal and the reaction in which the calcium produced by such decomposition forms various compounds in the magnesium molten metal.

When the stirring and holding step (S3) of the molten magnesium is completed, a magnesium mother alloy is produced through a casting step (S4) in which the molten magnesium is put into a mold and solidified.

At this time, the temperature of the mold in the casting step S4 may have a temperature range of room temperature (for example, 25 ° C) to 400 ° C. In addition, the mother alloy can be separated from the mold after cooling the mold to room temperature, but even when the mother alloy is solidified before the room temperature, the mother alloy can be separated from the mold.

Here, the mold may be any one selected from a mold, a ceramic mold, a graphite mold, and the like. In addition, casting methods include sand casting, die casting, gravity casting, continuous casting, low pressure casting, squeeze casting, lost wax casting, thixo casting, and the like.

Gravity casting may refer to a method of injecting a molten alloy into the mold using gravity, and low pressure casting may refer to a method of injecting molten metal into the mold by applying pressure to the molten surface of the molten alloy using gas. . Thixocasting is a casting technique in a semi-melt state that combines the advantages of conventional casting and forging. However, the present invention does not limit the type of mold and the manner of casting.

The magnesium master alloy thus prepared has a base having a plurality of regions that form a boundary and are separated from each other. At this time, a plurality of regions to be distinguished from each other may be a plurality of crystal grains which are typically divided into crystal grains, and as another example, a plurality of phase regions may be defined by two or more different phase glasses.

On the other hand, at the base of the magnesium mother alloy may be present by dispersing the calcium-based compound produced in the mother alloy manufacturing process. In this case, the calcium-based compound may be produced by reacting the calcium-based additive added in the base metal melt in the additive addition step (S2) with other elements in the magnesium base material, for example, magnesium and / or aluminum.

That is, the calcium-based additive is reduced to calcium in the process of adding and stirring the calcium-based additive to the magnesium molten metal. In general, since the calcium-based additives are thermodynamically more stable than magnesium, it is expected that the calcium-based additives will not be separated from the molten magnesium. However, experiments by the inventors have shown that such calcium-based additives are reduced in the molten magnesium. The reduced calcium can then react with other elements in the matrix, for example magnesium and / or aluminum, to form calcium-based compounds.

Therefore, the calcium-based additive is a source of calcium used to form the calcium-based compound formed in the magnesium mother alloy and is an additive element added to the base metal molten metal during the production of the mother alloy, and the calcium-based compound is supplied from the calcium-based additive. Calcium is a newly produced compound by reacting with other elements in the base metal.

Although calcium has a solid solubility for magnesium, it has been found that, as in the present invention, only a portion of the calcium reduced from the calcium-based additive in the molten magnesium is dissolved in the magnesium base, and most of it forms a calcium-based compound.

In this case, when the base material of the magnesium mother alloy is pure magnesium, the calcium-based compound that can be produced may be an Mg-Ca compound, and for example, Mg ₂ Ca. In addition, when the base material of the magnesium master alloy is a magnesium alloy, for example, a magnesium-aluminum alloy, the calcium compound that can be produced may include any one or more of an Mg-Ca compound, an Al-Ca compound, and an Mg-Al-Ca compound. have. For example, the Mg-Ca compound may be Mg ₂ Ca, the Al-Ca compound may include any one or more of Al ₂ Ca and Al ₄ Ca, and the Mg-Al-Ca compound is (Mg, Al) ₂ Ca Can be.

At this time, the calcium-based compound is likely to be distributed in the grain boundary, which is the boundary between the grains, or the boundary, which is the boundary between the phase regions. This boundary portion is an open structure compared to the inside of the grain or phase region, and has a relatively high energy, which can provide a favorable position for nucleation and growth of calcium-based compounds.

2A to 2D show the results of an Electron Probe Micro Analyzer (EPMA) analysis of a magnesium mother alloy prepared by adding calcium oxide (CaO) as a calcium compound to a magnesium-aluminum alloy as a magnesium mother alloy according to the present embodiment. .

Figure 2a shows the microstructure of the magnesium master alloy observed using back scattering electrons. As shown in FIG. 2A, the magnesium mother alloy exhibits a microstructure having a plurality of regions surrounded by a compound (white portion), that is, grains. The compound (white part) is formed along the grain boundaries. 2B to 2D show the results of mapping the components of the compound (white portion) region to EPMA, showing the distribution regions of aluminum, calcium and oxygen, respectively.

As shown in FIG. 2B and FIG. 2C, the compound (white portion of FIG. 2A) detected aluminum and calcium, but did not detect oxygen (FIG. 2D). From this, it can be seen that the Al-Ca compound produced by the reaction of calcium separated from calcium oxide (CaO) with aluminum contained in the base material is distributed in the grain boundary of the magnesium mother alloy. The Al-Ca compound may be Al ₂ Ca or Al ₄ Ca, which is an intermetallic compound.

On the other hand, the above EPMA results show that Al-Ca compounds are mainly distributed in the grain boundaries of the magnesium mother alloy, which is more likely to be distributed in the grain boundaries than in the grains due to the nature of the grain boundaries having an open structure as grain boundaries. It is interpreted because. However, the results of the analysis are not limited to the present invention, because all the calcium-based compounds are distributed only in the grain boundaries, and in some cases, such calcium-based compounds may be found inside the grains.

The magnesium mother alloy thus prepared is used for the purpose of being added to an aluminum alloy. At this time, as described above, in the magnesium master alloy, calcium supplied from the calcium-based additive added during the alloying process includes a calcium-based compound formed by reaction with magnesium and / or aluminum. These calcium compounds are all intermetallic compounds and have a melting point higher than that of aluminum (658 ° C.). As an example, the melting point of Al ₂ Ca or Al ₄ Ca, which is an Al—Ca compound, is 1079 ° C. and 700 ° C., respectively, which is higher than that of aluminum.

Therefore, when the mother alloy containing such a calcium-based compound is added to the aluminum molten metal, the calcium-based compound can be maintained without melting in the molten metal, when casting the molten metal to produce an aluminum alloy, the calcium in the aluminum alloy System compounds may be included.

Hereinafter, a method of manufacturing an aluminum alloy extruded material according to an embodiment of the present invention will be described.

The aluminum alloy extruded material according to an embodiment of the present invention may be manufactured by casting an aluminum alloy and extruding it into a predetermined shape. The production of the aluminum alloy may include providing a magnesium mother alloy and aluminum containing a calcium-based compound, forming a molten magnesium alloy and a molten aluminum, and casting the molten metal. Optionally, the aluminum alloy extruded material may undergo an appropriate heat treatment step after the extrusion step.

For example, in order to form a molten magnesium mother alloy and a molten aluminum, the molten aluminum may be first melted to form an aluminum molten metal, and the molten magnesium alloy may be formed by adding and dissolving a magnesium mother alloy containing a calcium compound. . Alternatively, the aluminum and magnesium mother alloys may be formed by mounting together in a melting apparatus such as a crucible and then heating them to dissolve together.

Extrusion of the aluminum alloy can be performed using an extrusion apparatus including a die having extrusion holes of a predetermined shape. For example, the aluminum alloy may be charged into a container and extruded through a die bonded to the front end of the container using a stem. Furthermore, such extruded materials may be subjected to additional heat treatment steps to relieve stress and to form additional reinforcement phases.

3 is a flowchart of a method of manufacturing an aluminum alloy using a method of first forming an aluminum molten metal as an embodiment of a method of manufacturing an aluminum alloy according to the present invention, and then adding and dissolving the magnesium mother alloy prepared by the method described above. .

As shown in FIG. 3, the method for producing an aluminum alloy includes an aluminum molten metal forming step (S11), a magnesium mother alloy addition step (S12), a stirring and holding step (S13), and a casting step (S14).

First, in the aluminum molten metal forming step (S11), aluminum is placed in a crucible and heated at 600 to 900 DEG C to form molten aluminum. The aluminum in the aluminum melt forming step S11 may be any one selected from pure aluminum, an aluminum alloy, and equivalents thereof. At this time, the aluminum alloy is, for example, 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, 7000 series and 8000 series Wrought aluminum or 100 series, 200 series, 300 series, 400 series It may be any one selected from among 500 series, 700 series casting aluminum.

Next, in the magnesium master alloy addition step (S12), the magnesium master alloy produced by the method already described above is added to the molten aluminum. At this time, the magnesium mother alloy used in the magnesium mother alloy addition step (S12) may be added 0.0001 to 30 parts by weight based on 100 parts by weight of aluminum. If the added magnesium master alloy is less than 0.0001 parts by weight, the effect of the addition of the magnesium master alloy (hardness, corrosion resistance, weldability) may be small. Also, when the magnesium master alloy exceeds 30 parts by weight, the characteristics of the original aluminum alloy are not exhibited.

At this time, the side of the magnesium mother alloy may be added to the bulk side, but the present invention is not limited thereto, and may have other side such as powder side, granule side. Also, the size of the magnesium master alloy is not limited.

When the magnesium master alloy is added, the calcium compound contained in the magnesium master alloy is also provided in the molten aluminum. As described above, the calcium-based compound provided into the molten aluminum may include any one or more of an Mg-Ca compound, an Al-Ca compound, and an Mg-Al-Ca compound.

At this time, a small amount of protective gas may be additionally provided to prevent oxidation of the magnesium master alloy. As the protective gas, ordinary SF6, SO2, CO2, HFC-134a, Novec ™ 612, an inert gas and its equivalent, or a mixed gas thereof can be used, thereby suppressing the oxidation of the magnesium master alloy.

However, this protective gas is not necessarily required in the present invention, and may not be provided. That is, in the case of adding a magnesium mother alloy containing a calcium-based compound as in the embodiment of the present invention, the resistance to ignition is increased by increasing the oxidation resistance of the magnesium mother alloy, and magnesium that does not contain a conventional calcium-based compound is added. Compared with the case of addition, the presence of impurities such as oxides in the molten metal is significantly reduced. Therefore, in the case of using the aluminum alloy manufacturing method of the present invention, the cleanliness of the aluminum melt can be greatly improved without using the protective gas, and the quality of the melt can be remarkably improved.

Next, in the stirring and holding step (S13), the aluminum molten metal is stirred or maintained for 1 to 400 minutes. If the stirring and holding time is less than 1 minute, the magnesium mother alloy is not sufficiently mixed with the aluminum molten metal. If the stirring and holding time is more than 400 minutes, the stirring and holding time of the aluminum molten metal becomes unnecessarily long.

When the stirring and holding step (S13) of the molten aluminum is completed, an aluminum alloy is produced through a casting step 14 in which the molten aluminum is put into a mold and solidified. At this time, the temperature of the mold in the casting step (S14) may have a temperature range of room temperature (for example, 25 ℃) to 400 ℃. In addition, the mother alloy can be separated from the mold after cooling the mold to room temperature, but even when the mother alloy is solidified before the room temperature, the mother alloy can be separated from the mold. Since the magnesium master alloy manufacturing method has been described in detail with respect to the casting method, the description is omitted.

The aluminum alloys produced are 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, 7000 series and 8000 series wrought aluminum or 100 series, 200 series, 300 series, 400 series, 500 series , 700 series casting aluminum may be any one selected from.

As described above, when the magnesium mother alloy containing the calcium compound is added, the mechanical properties of the cast aluminum alloy are remarkably improved due to the improvement in cleanliness of the molten aluminum. That is, due to the improvement of the cleanliness of the molten metal, there is no impurities such as oxides or inclusions in the aluminum alloy cast therefrom that deteriorate the mechanical properties, and bubbles in the cast aluminum alloy are also significantly reduced. As the inside of the cast aluminum alloy has a cleaner state than the conventional one, the aluminum alloy according to the present invention not only has excellent yield strength and tensile strength as compared with the conventional one, but also has very good mechanical properties such that the elongation is further improved. To have.

Therefore, even when manufacturing an aluminum alloy having the same magnesium content, due to the effect of cleaning the quality of the molten metal according to the present invention can be a good characteristic of the cast aluminum alloy.

In addition, the loss in the molten magnesium of aluminum added to the aluminum is reduced, and even if a smaller amount of magnesium is added, it is possible to manufacture substantially the same amount of magnesium contained in the aluminum alloy, which is economical aluminum. The alloy can be manufactured.

In addition, when the magnesium mother alloy according to the present invention is added to the molten aluminum, the magnesium instability in the molten aluminum is significantly improved compared to the conventional, it is possible to easily increase the content of magnesium compared to the conventional.

Magnesium can be dissolved in aluminum up to 15% by weight and can improve the mechanical properties of aluminum alloys when dissolved. For example, adding magnesium to a 300 series or 6000 series aluminum alloy may improve the strength and elongation of the aluminum alloy.

However, due to the high oxidative properties of magnesium described above, oxides and inclusions caused by magnesium may be mixed in the molten metal and degrade the quality of the aluminum alloy. This problem is exacerbated as the amount of magnesium added increases. Even if it is difficult to stably increase the content of magnesium added to the aluminum molten metal.

On the contrary, since the magnesium mother alloy can be stably added to the molten aluminum in accordance with the present invention, it is possible to easily increase the content of magnesium in the aluminum alloy as compared with the conventional art and to secure castability while increasing the proportion of magnesium. Therefore, by adding the magnesium master alloy according to the present invention to the 300 series or 6000 series aluminum alloy, it is possible to suppress the incorporation of oxides or inclusions to improve not only castability but also strength and elongation. 500 series or 5000 series aluminum alloys can be made available.

As an example, the aluminum alloy according to the present invention can easily increase the solid solution of magnesium to 0.1% by weight or more, as well as 5% by weight or more, even 6% by weight or even more than 10% by weight to 15%.

The stability of magnesium in this aluminum alloy can also work advantageously in the waste recycling of the aluminum alloy. For example, when the magnesium content is high in the process of recycling waste for aluminum alloy production, a process of reducing it to a required ratio (hereinafter referred to as de-megging process) is performed. At this time, the lower the ratio of magnesium content required, the more difficult and required cost of the de-megging process.

For example, for 383 aluminum alloys it is technically easy to lower magnesium to 0.3% by weight, but it is very difficult to lower it to 0.1% by weight. In addition, chlorine gas (Cl ₂ ) is used to lower the ratio of magnesium, and the use of such chlorine gas is harmful to the environment and additionally causes a cost.

However, according to the present invention, the aluminum alloy prepared by using a magnesium mother alloy containing a calcium-based compound has a technical, environmental, and cost advantage because it is possible to maintain a magnesium ratio of 0.3% by weight or more.

In addition, the aluminum alloy according to the present invention may further include a step of adding a small amount of iron (Fe) after, for example, the aluminum molten metal forming step (S11) or the master alloy addition step (S12). The amount of iron added at this time may have a smaller value than in the prior art. That is, in the case of casting, for example, die-casting an aluminum alloy, a problem arises that the mold is damaged due to sintering between a mold made of an iron-based metal and an aluminum casting material. 1.0 to 1.5 wt.% Of iron has been added to the aluminum alloy. However, the addition of iron may cause another problem that the corrosion resistance and elongation of the aluminum alloy is reduced.

However, as described above, the aluminum alloy according to the present invention may have a high content of magnesium, and when a high content of magnesium is added, a significantly smaller proportion of iron is added to the mold, which has appeared in the related art. Sedimentation problems can be greatly improved. Therefore, it is possible to solve the problems of corrosion resistance and elongation reduction that are conventionally found in die cast aluminum alloy castings.

At this time, the content of iron (Fe) added in the process of manufacturing the above-described aluminum alloy may be 1.0% by weight or less (greater than 0) relative to the aluminum alloy, more strictly 0.2% by weight or less (greater than 0). Accordingly, the base of the aluminum alloy may include iron in the corresponding composition range.

Hereinafter, the characteristics of the aluminum alloy manufactured according to the aluminum alloy manufacturing method of the present invention will be described in detail.

The aluminum alloy prepared according to the manufacturing method of the present invention includes an aluminum base and a calcium-based compound present in the aluminum base, wherein magnesium may be dissolved in the aluminum base.

Magnesium may be dissolved in the aluminum matrix of 0.1 to 15% by weight. In addition, the aluminum base may have a solid solution of less than or equal to the solid solution limit, for example, 500 ppm or less.

As described above, the calcium reduced from the calcium-based additives added in the magnesium master alloy is mostly present as a calcium-based compound, and only a part of it is dissolved in the magnesium matrix. When the magnesium master alloy is added to the molten aluminum, as the dissolved calcium in the magnesium master alloy is diluted, the amount of calcium dissolved in the base of the actual aluminum alloy also has a small value below the solid solution limit.

Therefore, the aluminum alloy according to the present invention has a structure in which the calcium base compound is separately formed on the aluminum base while the calcium base is dissolved in the aluminum base below the solid solution limit, for example, 500 ppm or less.

 In this case, the aluminum base may have a plurality of regions that form a boundary and are separated from each other. In this case, the calcium-based compound may exist within the boundary or region.

An aluminum base may be defined as a metal structure containing aluminum as a main component, in which other alloying elements are dissolved or in which other alloying elements other than calcium-based compounds or compounds containing the alloying elements are formed as separate phases. .

At this time, a plurality of regions to be distinguished from each other may be a plurality of crystal grains which are typically divided into crystal grains, and as another example, a plurality of phase regions may be defined by two or more different phase glasses.

In the case of the aluminum alloy according to the present invention may have an effect of improving the mechanical properties resulting from the calcium-based compound formed in the magnesium mother alloy. As described above, when the magnesium master alloy is added to the molten aluminum, the calcium compound contained in the magnesium master alloy is also added to the molten metal. The calcium compound is an intermetallic compound formed by the reaction between calcium and other metal elements. All have a melting point higher than that of aluminum.

Therefore, when the mother alloy containing such a calcium-based compound is added to the aluminum molten metal, the calcium-based compound can be maintained without melting in the molten metal, and when casting the molten metal to produce an aluminum alloy, the calcium in the aluminum alloy System compounds may be included.

Such a calcium-based compound may be dispersed and distributed in the fine particle side in the aluminum alloy. At this time, the calcium-based compound is a high-strength material compared to aluminum known as an intermetallic compound, and therefore, the strength of the aluminum alloy may be increased due to the dispersion distribution of the high-strength material.

On the other hand, the calcium-based compound may provide a place where nucleation occurs in the process of the aluminum alloy is phased from the liquid phase to the solid phase. In other words, the transition from the liquid phase to the solid phase during solidification of the aluminum alloy is in the form of nucleation and growth, wherein the calcium-based compound and the liquid phase function as the calcium-based compound itself functions as a heterogeneous nucleation site. At this interface, nucleation occurs preferentially for transition to the solid phase. The nucleated solid phase grows while forming around the calcium compound.

When the calcium-based compound is distributed in a plurality, the solid phases grown at the interface of each calcium-based compound meet each other to form a boundary, and the boundary thus formed may form a grain boundary or an boundary boundary. Therefore, when the calcium-based compound functions as a nucleation site, the calcium-based compound is present inside the grains or the phase region, and the grains or the phase region may have a smaller effect than the case where the calcium-based compound does not exist. Will be.

In addition, the calcium-based compound may be distributed in a grain boundary which is a boundary between grains or an upper boundary which is a boundary between phase regions. This boundary portion is an open structure compared to the inside of the grain or phase region, and has a relatively high energy, which can provide a favorable position for nucleation and growth of calcium-based compounds.

When the calcium-based compound is distributed in the grain boundary or the boundary of the aluminum alloy, the calcium-based compound acts as an obstacle of grain boundary or the boundary boundary, and the movement of the grain boundary or the boundary boundary is suppressed to reduce the average size of the grain or the boundary boundary. have.

Therefore, in the case of the aluminum alloy according to the present invention, such a calcium-based compound may have a finer and smaller grain or phase region size on average.

The refinement of the grain or phase region due to such a calcium-based compound can bring about an effect of improving the strength and elongation of the aluminum alloy.

Aluminum bases are also available in 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, 7000 series and 8000 series plastic processing (Wrought) aluminum or 100 series, 200 series, 300 series, 400 series, 500 series, 700 It may be any one selected from the series casting aluminum.

In this case, the total amount of calcium in the aluminum alloy according to the present invention may be present in an amount of 0.0001 to 10 parts by weight based on 100 parts by weight of aluminum. The total amount of calcium is the sum of the calcium present in the aluminum base and the calcium-based compound dissolved in the aluminum base.

At this time, most of the calcium present in the aluminum alloy is present in the side of the calcium-based compound, and the high dose of calcium dissolved in the aluminum matrix has a small value. That is, in the magnesium mother alloy prepared by adding the calcium-based additive as described above, most of the calcium reduced from the calcium-based additive forms a calcium-based compound without being dissolved in the magnesium matrix. Therefore, when the magnesium master alloy is added to manufacture aluminum, the amount of calcium dissolved in the magnesium master alloy shows a small value, so that the amount of calcium employed in the aluminum base through the magnesium master alloy is very small, for example, 500 ppm or less. To have.

On the other hand, the aluminum matrix may have from 0.1 to 15% by weight of magnesium dissolved, further 5 to 15% or more, further 6 to 15% by weight and even more 10 to 15% by weight.

That is, as described above, in the case of using a magnesium mother alloy prepared by adding a calcium-based additive as in the aluminum alloy manufacturing method of the present invention, the amount of magnesium added in the molten aluminum can be stably increased. The high dose of magnesium that is dissolved in it also increases.

This increase in magnesium capacity can greatly contribute to the improvement of aluminum alloy strength due to solid solution strengthening and heat treatment, and exhibits excellent castability and excellent mechanical properties compared to conventional commercial alloys.

Hereinafter, experimental examples are provided to help the 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.

Table 2 shows the aluminum alloy prepared by adding magnesium oxide (CaO) as a calcium-based additive to aluminum (Experimental Example 1) and pure magnesium without addition of calcium-based additives to aluminum. This table compares the casting characteristics of an aluminum alloy (Comparative Example 1).

Specifically, Experimental Example 1 was prepared by adding 305 g of magnesium mother alloy to 2750 g of aluminum, and Comparative Example 1 was prepared by adding 305 g of pure magnesium to 2750 g of aluminum. At this time, the magnesium mother alloy used in Experimental Example 1 used a magnesium-aluminum alloy as a base material, and the weight ratio of calcium oxide (CaO) to the base material was 0.3.

Experimental Example 1 Comparative Example 1 Miss Dross
(Impurities floating on the surface of the molten metal) 206 g 510 g Mg content in Al alloy 4.89% 2.65% Molten fluidity good Bad Hardness
(HR Load 60kg, 1/16 "Steel Ball) 92.6 92

Referring to Table 2, it can be seen that the amount of impurities (Dross amount) floating on the surface of the molten metal is significantly smaller when the magnesium master alloy (Experimental Example 1) is added than when pure magnesium is added (Comparative Example 1). Can be. The magnesium content in the aluminum alloy was found to be higher when the magnesium mother alloy was added (Experimental Example 1) than when pure magnesium was added (Comparative Example 1). From this, it can be seen that the loss of magnesium is significantly reduced compared to the method of adding pure magnesium, according to the production method of the present invention.

In addition, it can be seen that the flowability of the molten metal and the hardness of the aluminum alloy are also better when the magnesium mother alloy is added (Experimental Example 1) than when pure magnesium is added (Comparative Example 1).

4A and 4B show the results of observing the state of the melt according to Experimental Example 1 and Comparative Example 1. 4A and 4B, in Experimental Example 1 (FIG. 4A), the molten metal is in good condition. In Comparative Example 1 (FIG. 4B), the surface of the molten metal turns black due to the oxidation of magnesium. Able to know.

5A and 5B show the results of comparing casting surfaces of aluminum alloys according to Experimental Example 1 and Comparative Example 1. FIG.

5A and 5B, the surface of the cast material of the aluminum alloy to which the magnesium mother alloy of Experimental Example 1 (Fig. 5A) was added was cleaner than the cast material of the aluminum alloy to which the pure magnesium was added to Comparative Example 1 (Fig. 5B). You can see that. This is because castability is improved by calcium oxide (CaO) added to the magnesium mother alloy. That is, the aluminum alloy (Comparative Example 1) to which pure magnesium is added shows signs of ignition on the surface due to the oxidation of pure magnesium during casting, while the aluminum alloy cast using a magnesium mother alloy to which calcium oxide (CaO) is added. In the case of (Experimental Example 1), the ignition phenomenon is suppressed and a clean surface can be obtained.

From this, when the magnesium mother alloy is added, it can be seen that the quality of the molten metal is remarkably improved as compared with the addition of pure magnesium, thereby improving castability.

 6A and 6B are results of energy dispersive spectroscopy (EDS) analysis using a scanning electron microscope (SEM) of aluminum alloys according to Experimental Example 1 and Comparative Example 1. FIG.

6A to 6B, in the aluminum alloy added with pure magnesium of Comparative Example 1 (FIG. 6B), only magnesium and aluminum were detected, whereas magnesium added with calcium oxide (CaO) of Experimental Example 1 (FIG. 6A) was added. In the aluminum alloy to which the master alloy is added, the presence of calcium is confirmed in the aluminum alloy, and magnesium and aluminum are detected at the same position, and oxygen is hardly detected. From this it can be seen that calcium is reduced from calcium oxide (CaO) and then reacts with magnesium and / or aluminum to exist as a calcium-based compound.

7A shows the results of observing the structure of the aluminum alloy of Experimental Example 1 with EPMA, and FIGS. 7B to 7E show mapping results of aluminum, calcium, magnesium, and oxygen, respectively, as component mapping results using EPMA.

As can be seen from Figs. 7b to 7d, calcium and magnesium were detected at the same position on the aluminum matrix, and oxygen was not detected as in Fig. 7e.

This is consistent with the result of FIG. 6a, from which calcium can be reduced from calcium oxide (CaO) and then reacted with magnesium and / or aluminum to be present as a calcium-based compound.

Table 3 shows the mechanical properties of the aluminum alloy according to the experimental examples and the aluminum alloy according to the comparative examples. Experimental Example 2, Experimental Example 3 and Experimental Example 4 each represent an aluminum alloy (extruded material) prepared by adding a magnesium mother alloy containing calcium oxide (CaO) to 5056 alloy, 6061 alloy and 7075 alloy which are commercial aluminum alloys, respectively. Comparative example 2, comparative example 3, and comparative example 4 show commercial 5056 alloy, 6061 alloy, and 7075 alloy (comparative example 2, comparative example 3, and comparative example 4), respectively.

The specimens according to Experimental Examples 1, 2 and 3 were subjected to T6 heat treatment by casting after extrusion, and the data of Comparative Examples 1, 2 and 3 refer to values in the ASM standard (T6 heat treatment data). In Table 3, aluminum alloy refers to an aluminum alloy extruded material which is substantially heat treated after extrusion.

Tensile Strength (MPa) Yield strength (MPa) Elongation (%) Experimental Example 2 (5056) 424 231 34.2 Comparative Example 2 (5056) 290 152 35 Experimental Example 3 (6061) 349 329 17.8 Comparative Example 3 (6061) 310 276 12 Experimental Example 4 (7075) 662 610 13.6 Comparative Example 4 (7075) 572 503 11

As shown in Table 3, although the aluminum alloy according to the experimental example of the present invention exhibits higher values in tensile strength and yield strength than commercial aluminum alloys containing no calcium compound, the elongation is excellent or equivalent. In particular, in the case of the 5000 series alloy, it can be seen that the aluminum alloy according to the present invention (Experimental Example 2) can maintain the elongation at an equivalent level while increasing the tensile strength by approximately 1.46 times compared to the commercial aluminum alloy (Comparative Example 2). have. Furthermore, in the case of the 6000 series alloy and the 7000 series alloy, the aluminum alloys (Experimental Examples 3 and 4) according to the present invention can increase both tensile strength and elongation compared to conventional aluminum alloys (Comparative Examples 3 and 4). It can be seen.

More specifically, in terms of tensile strength, Experimental Example 2 is about 1.46 times that of Comparative Example 2, Experimental Example 3 is about 1.13 times that of Comparative Example 3, and Experimental Example 4 is about 1.16 times that of Comparative Example 4. That is, it can be seen that the tensile strength of the experimental examples is about 1.13 ~ 1.46 times higher than the tensile strength of the comparative examples. On the other hand, in terms of elongation, it can be seen that Experimental Example 2 is about 0.98 times that of Comparative Example 2, Experimental Example 3 is about 1.48 times that of Comparative Example 3, and Experimental Example 4 is about 1.24 times that of Comparative Example 4.

In general, when the strength is increased in the alloy, the elongation is relatively decreased. However, the aluminum alloy according to the experimental example of the present invention shows an ideal characteristic that the elongation is also increased with increasing the strength. It was mentioned above that this result may be related to the improvement of the cleanliness of the molten aluminum alloy.

8 to 10 are photographs comparing and comparing the microstructures of the experimental examples and the comparative examples of Table 3.

Referring to FIG. 8, the crystal grains of Experimental Example 2 (FIG. 8A) had an average size of about 25 μm, and the crystal grains of Comparative Example 2 (FIG. 8B) had an average size of about 60 μm. That is, it can be seen that the grain size of Experimental Example 2 is only about 0.42 times as compared to the grain size of Comparative Example 2. Referring to FIG. 9, the crystal grains of Experimental Example 3 (FIG. 9A) had an average size of about 30 μm, and the grains of Comparative Example 3 (FIG. 9B) had an average size of about 50 μm. That is, it can be seen that the grain size of Experimental Example 3 is only about 0.6 times as compared to the grain size of Comparative Example 3. Referring to FIG. 10, the crystal grains of Experimental Example 4 (FIG. 9A) had an average size of about 25 μm, and the grains of Comparative Example 4 (FIG. 9B) had an average size of about 50 μm. That is, it can be seen that the grain size of Experimental Example 4 was only about 0.5 times (half) compared to the grain size of Comparative Example 4.

Therefore, it can be seen that the crystal grains of the aluminum alloy (extruded material) according to the experimental examples of the present invention are significantly finer than the commercial aluminum alloy (extruded material). For example, the grain size of the aluminum alloy (extruded material) according to the experimental examples according to the experimental examples was found to have a range of about 0.42 to about 0.6 times the grain size of the commercial aluminum alloy (extruded material).

The grain refinement in the aluminum alloy of the experimental examples is determined by the growth of the grain boundary by the calcium-based compound distributed in the grain boundary or because the calcium-based compound functions as a nucleation site during solidification. It is judged that the aluminum alloy according to the examples is one of the causes showing excellent mechanical properties.

Table 4 compares the mechanical properties of the aluminum alloy according to the experimental examples and the aluminum alloy according to the comparative examples according to the heat treatment conditions. Comparative Example 3-1, Comparative Example 3-2, and Comparative Example 3-3 show specimens (extruded materials) prepared by casting and extruding a commercial 6061 alloy and heat-treating under T1, T5, and T6 conditions, respectively, and Experimental Example 3-1. , Experimental Example 3-2 and Experimental Example 3-3 cast and extrude an aluminum alloy prepared by adding a magnesium master alloy containing calcium oxide (CaO) to a 6061 alloy, which is a commercial aluminum alloy, and then extruded T1, T5, and T6, respectively. A specimen prepared by heat treatment under conditions is shown. In Table 4, aluminum alloy refers to an aluminum alloy extruded material which is substantially heat treated after extrusion.

Hardness (HRF) Tensile Strength (MPa) Yield strength (MPa) Elongation (%) Experimental Example 3-1 (T1) 47.5 117 215 20.9 Comparative Example 3-1 (T1) 43.7 108 200 20.7 Experimental Example 3-2 (T5) 83.4 203 269 16.1 Comparative Example 3-2 (T5) 63.5 160 234 17.8 Experimental Example 3-3 (T6) 92.5 385 405 15.7 Comparative Example 3-3 (T6) 94.1 372 396 14.5

As shown in Table 4, commercial aluminum alloys (Comparative Examples 3-1 to 3-3) in which the aluminum alloys (Experimental Examples 3-1 to 3-3) according to the embodiment of the present invention do not contain calcium-based compounds regardless of the heat treatment conditions. Elongation is better or equivalent even though it shows higher values in tensile strength and yield strength than in 3-3).

In general, when the strength is increased in the alloy, the elongation is relatively decreased. However, the aluminum alloy according to the experimental example of the present invention shows an ideal characteristic that the elongation is also increased with increasing the strength. It was mentioned above that this result may be related to the improvement of the cleanliness of the molten aluminum alloy.

On the other hand, the hardness after heat treatment under the conditions of T1 and T5 was higher in aluminum alloys (Experimental Example 2, Experimental Example 3) according to the embodiments of the present invention than commercial aluminum alloys (Comparative Example 2, Comparative Example 3), but T6 conditions After the heat treatment of the commercial aluminum alloy (Comparative Example 4) was higher than the aluminum alloy (Experimental Example 4) according to the embodiment of the present invention.

The foregoing description of specific embodiments of the invention has been presented for purposes of illustration and description. Therefore, the present invention is not limited to the above embodiments, and various modifications and changes can be made by those skilled in the art within the technical spirit of the present invention in combination with the above embodiments. Do.

Claims (17)

Providing a magnesium master alloy comprising a calcium-based compound in a magnesium matrix;
Adding the magnesium mother alloy into the molten aluminum;
Casting the molten metal to produce an aluminum alloy; And
Comprising the step of extruding the aluminum alloy, a method for producing an aluminum alloy extruded material. The method of claim 1, further comprising heat treating the aluminum alloy extruded material after extruding the aluminum alloy. The method of claim 1, wherein the calcium compound comprises at least one of Mg-Ca compound, Al-Ca compound and Mg-Al-Ca compound,
The Mg-Ca compound includes Mg ₂ Ca, the Al-Ca compound includes any one or more of Al ₂ Ca and Al ₄ Ca, the Mg-Al-Ca compound is (Mg, Al) ₂ Ca A method of producing an aluminum alloy extrusion material comprising. The method of claim 1, wherein the magnesium master alloy is prepared by adding a calcium-based additive to the molten metal of the base metal based on a magnesium alloy containing pure magnesium or aluminum. The aluminum alloy extruded material according to claim 4, wherein the calcium-based compound is formed by dispersing and adding a calcium-based additive to the upper surface of the magnesium molten metal layer, and then exhausting at least a portion of the calcium-based additive in the magnesium-molten metal. Manufacturing method. The method for producing an aluminum alloy extruded material according to claim 5, wherein the calcium compound is formed by exhausting in the molten magnesium so that the calcium additive does not substantially remain in the magnesium master alloy. The method of manufacturing an aluminum alloy extruded material according to claim 6, wherein stirring is performed on an upper layer of the magnesium molten metal, and the stirring is performed at an upper layer of 20% or less of the total depth of the magnesium molten metal. The method of claim 4, wherein the calcium-based additive comprises at least one of calcium oxide (CaO), calcium cyanide (CaCN ₂ ), and calcium carbide (CaC ₂ ). The method of claim 4, wherein at least a portion of the calcium-based additive is exhausted in the molten metal of the base material,
The calcium-based compound is a method of producing an aluminum alloy extruded material that is produced by the reaction of calcium supplied from the calcium-based additives with magnesium or aluminum of the base material. The magnesium master alloy is 0.0001 to 30 parts by weight based on 100 parts by weight of aluminum,
The calcium-based additive is added in the range of 0.0001 to 30 parts by weight based on 100 parts by weight of the base material, a method for producing an aluminum alloy extruded material. It is prepared by extruding the cast aluminum alloy by adding a magnesium master alloy in which the calcium-based compound is distributed in the magnesium matrix at 0.0001 to 30 parts by weight based on 100 parts by weight of aluminum in the aluminum molten metal,
An aluminum alloy extruded material comprising the calcium-based compound in an aluminum base. The aluminum alloy extruded material according to claim 11, wherein the calcium-based compound comprises at least one of an Mg-Ca compound, an Al-Ca compound, and an Mg-Al-Ca compound. 12. The aluminum alloy extruded material as recited in claim 11, wherein said aluminum matrix is solid solution of magnesium in the range of 0.1 to 15 wt%. 12. The aluminum alloy extruded material of claim 11, further comprising 1.0 wt% or less (greater than 0) of iron (Fe) in the aluminum matrix. Aluminum base; And
It includes; calcium-based compound present in the aluminum base;
An aluminum alloy extruded material having a higher strength than an aluminum alloy extruded material manufactured under the same conditions without containing the calcium compound. The aluminum alloy extruded material according to claim 15, wherein the average grain size of the aluminum alloy extruded material is smaller than that of the aluminum alloy extruded material prepared under the same conditions without the calcium-based compound. 16. The aluminum alloy extruded material according to claim 15, wherein the tensile strength is greater and the elongation is greater than or equal to that of the aluminum alloy extruded material prepared under the same conditions without the calcium-based compound.

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