KR20200027664A - Mg-Al Alloy Cast Method - Google Patents

Abstract

The present invention provides a magnesium-aluminum alloy casting method, which includes the following steps of: charging and dissolving aluminum ingot in a preheated reverberatory furnace; inputting a first flux into the reverberatory furnace to remove oxides generated during dissolution of the aluminum ingot; charging AlCa mother alloy to the reverberatory furnace; charging Mg mother alloy to the reverberatory furnace; and introducing a second flux into the reverberatory furnace to generate Cl2 for removing magnesium oxide and calcium oxide by a process reaction.

Description

Magnesium-Aluminum Alloy Casting Method {Mg-Al Alloy Cast Method}

The present invention relates to a magnesium-aluminum alloy casting method, and more particularly, to a magnesium-aluminum alloy casting method for suppressing the production of magnesium and aluminum oxide, and removing the produced oxide.

Conventional magnesium alloys are alloys that are lighter in weight and superior in corrosion resistance than aluminum alloys. Currently, commercially available high-content magnesium aluminum alloy is an AC7A alloy, which is mainly produced by producers who alloy with a crucible with a magnesium content of 3.5 to 5.5%.

The biggest problem is that the oxidation of magnesium occurs during the manufacture of magnesium alloys, and current crucible manufacturers use oxides of beryllium (Be) to suppress oxidation. Beryllium is currently considered as a regulated item.

In Patent Document 1, in order to minimize the formation of oxides, a step of forming a molten metal in which aluminum and magnesium having a content of 8 to 10% are dissolved, a degassing step for removing gas from the formed molten metal, and impurities in the degassed molten metal Disclosed is an aluminum alloy casting method including a filtering step of filtering out and a billet forming step of injecting the filtered molten metal into a mold to set a high-purity substance down and harden.

The addition of Ca in the Al-Mg alloy has the effect of suppressing oxidation by suppressing the reaction of oxygen in the atmosphere by the formation of Al ₄ Ca and the formation of Mg ₂ Ca film.

If the Al crystal grains are atomized as much as possible to facilitate the employment of Mg in Al and to disperse the precipitate Al ₃ Mg ₂ , mechanical properties may be further increased.

In the case of degassing by applying FLUX to remove oxidizing inclusions and hydrogen gas in the molten metal, if there is too much decomposable chlorine (Cl ₂ ) gas or fluorine (F) gas, the effective Ca is lost to CaCl ₂ or CaF ₂ and oxidize. Proceeds. Therefore, it should be used properly in the theoretical scope.

Korean Patent Publication No. 10-2017-0095026 (2017.8.22)

The present invention has been devised to solve the above problems, and one object of the present invention is to contain an appropriate amount of Ca, suppress the production of magnesium oxide, aluminum oxide, spinel (Al ₂ MgO ₄ ), and the produced oxide It is to provide a method for removing.

In addition, another object of the present invention is to improve the degradability of FLUX, minimize the content of Cl and F, suppress the disappearance of Ca, an oxidation inhibitory element, and increase the solubility of Mg in Al by atomizing grains, It is to provide a method of controlling the rate of oxidation by dispersing Mg homogeneously and alloying in a low temperature atmosphere.

On the other hand, another object of the present invention is to provide a method for improving the mechanical properties by minimizing the amount of Mg oxidation and inclusions.

In order to solve the above problems, the magnesium-aluminum alloy casting method of the present invention comprises the steps of charging and dissolving an aluminum ingot in a preheated reflector; Inputting a first flux into the reflector to remove oxides generated during the dissolution of the aluminum ingot; Charging an AlCa mother alloy to the reflection furnace; Charging an Mg mother alloy to the reflection furnace; And introducing a second flux into the reflection furnace to generate Cl ₂ to remove magnesium oxide and calcium oxide by a process reaction.

According to an example related to the present invention, the magnesium-aluminum alloy casting method of the present invention further includes a degassing step performed using nitrogen and SF ₆ gas to clean the molten metal and enable removal of hydrogen gas.

The magnesium-aluminum alloy casting method of the present invention may further include a step of stabilizing for a predetermined period of time to remove inclusions floating on the surface of the molten metal after the degassing step.

According to another example related to the present invention, the magnesium-aluminum alloy casting method of the present invention may further include reacting by introducing Ti and B into the molten metal after the step of introducing the first flux.

The Ti is preferably 20 to 25 ppm, and the B is preferably 20 to 25 ppm.

In the step of charging the AlCa mother alloy to the reflection furnace, charging of the AlCa mother alloy is performed at a temperature of 680 to 700 ° C, the content of Ca in the AlCa mother alloy is 10%, and the AlCa mother alloy is It may have a content of 350 to 450 ppm in the molten metal.

According to another example related to the present invention, the magnesium-aluminum alloy casting method of the present invention after the step of charging the AlCa mother alloy to the reflective furnace, the 680 to 50 to 70 minutes to enable the formation of Al ₄ Ca The method may further include maintaining a temperature of 700 ° C.

In the step of charging the Mg mother alloy to the reflection furnace, charging of the Mg mother alloy is performed at a temperature of 680 to 700 ° C, and the Mg mother alloy may have a content of 7 to 7.5% in the entire molten metal.

According to another example related to the present invention, after the step of charging the Mg mother alloy to the reflector, the temperature of the 680 to 700 ℃ for 50 to 70 minutes to 50 to form a homogeneous equilibrium state to complete decomposition of Mg It may further include the step of maintaining.

The process reaction may be a MgCl ₂ -KCl-MgO process reaction or a CaCl ₂ -NaCl-CaO process reaction.

The magnesium-aluminum alloy casting method of the present invention is caused by pores, Mg oxide, impurities, etc., by the use of calcium (Ca) content (ppm), process time, and degassing (containing less than 30% of the appropriate amount of Cl ₂ ). By minimizing defects, it is possible to improve the quality of a lightweight aluminum alloy ingot having good strength.

The magnesium-aluminum alloy casting method of the present invention can not only increase the high capacity of Mg by ultra-fine-graining the grains of aluminum, but also homogeneously disperse Al ₃ Mg ₂ precipitated during the solidification process of the alloy to homogenize the mechanical properties and Corrosion resistance can be improved.

In the magnesium-aluminum alloy casting method of the present invention, as a part of the degassing method, H + (hydrogen fluoride) is formed by introducing a mixed gas containing F such as Ar + SF ₆ , N ₂ + SF ₆ into the molten metal to form hydrogen saturation Can be minimized, and the surface oxidation is suppressed by reducing the distribution of oxygen in the surface layer.

Magnesium of the invention the aluminum alloy casting method using a predetermined amount of chlorine (Cl ₂₎ that the content of degassing claim minimize impurities and the hydrogen saturation and removal of aluminum oxide and, MgCl ₂ and CaCl ₂ formed by the Cl ₂ By forming a process reaction of MgCl ₂ -KCl-MgO, a process reaction of CaCl ₂ -NaCl-CaO or melting at a low melting point and removing magnesium oxide and calcium oxide, mechanical properties such as yield strength, tensile strength and elongation Can be improved.

The magnesium-aluminum alloy casting method of the present invention has a very high economic / technologically high ripple effect in the transportation industry field, the electronics industry field, as well as the zinc alloy counterpart material by enabling high-volume production by suppressing oxidation of the high-content magnesium aluminum alloy. There is.

1 is a flow chart showing a magnesium-aluminum alloy casting method according to an example of the present invention.
Figure 2 is a flow chart showing a magnesium-aluminum alloy casting method according to another example of the present invention.
3 is a graph showing the relationship between the molar concentration of MgO and temperature in MgCl ₂ and MgO.
4 is a graph showing the relationship between the molar concentration of MgCl ₂ and temperature in KCl ₂ and MgCl ₂ .
5 is a graph showing the relationship between the molar concentration of CaO and temperature in CaCl ₂ and CaO.
6 is a graph showing the relationship between the molar concentration of NaCl and temperature in CaCl ₂ and NaCl.

Hereinafter, exemplary embodiments disclosed herein will be described in detail with reference to the accompanying drawings, but the same or similar reference numerals are assigned to the same or similar elements, and overlapping descriptions thereof will be omitted. The suffix "part" for the components used in the following description is given or mixed only considering the ease of writing the specification, and does not have a meaning or a role distinguished from each other in itself. In addition, in describing the embodiments disclosed in the present specification, when it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed herein, detailed descriptions thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed in the specification is not limited by the accompanying drawings, and all modifications included in the spirit and technical scope of the present invention , It should be understood to include equivalents or substitutes.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from other components.

Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this application, the term "comprises" is intended to indicate the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, one or more other features or numbers, steps, It should be understood that it does not preclude the existence or addition possibility of the operation, components, parts or combinations thereof.

In the magnesium-aluminum alloy casting method (S100) of the present invention, an aluminum mass is charged and dissolved in a preheated reflector (S10), a first flux is introduced into the reflector (S20), and an AlCa mother alloy is charged in the reflector. It includes a step (S30), the step of charging the Mg mother alloy to the reflection path (S40) and the step of introducing the second flux to the reflection path (S50).

In the present invention, the reflective furnace is a configuration in which a molten aluminum alloy is melted to generate a molten metal, and a mother alloy is added to an alloy conforming to the KS standard to cast an aluminum alloy conforming to the standard and then sent to the furnace. The reflection furnace may be operated, for example, by heating using refined oil. In addition, the reflector may be a 20ton class high content reflector.

In the magnesium-aluminum alloy casting method (S100) of the present invention, prior to the step (S10) of charging and dissolving an aluminum ingot in a preheated reflector, aluminum ingot, Mg, AlCa (Ca content 10%), liquid nitrogen, SF ₆ Gas, a degassing agent (Cl content 30%), 20 ~ 25ppm content of Ti, 20 ~ 25ppm content may further include the step of preparing B.

In the step (S10) of charging and dissolving the aluminum ingot in the preheated reflective furnace, the reflective furnace may be preheated to 400 ° C, and the aluminum ingot may be charged and dissolved in the reflective furnace at 700 to 720 ° C.

By introducing the first flux into the reflective furnace (S20), it is possible to remove oxides generated during the melting process of the aluminum ingot. The oxide generated during the dissolution of the aluminum ingot may be, for example, Al ₂ O ₃ , and the first flux should be made of a material capable of removing the oxide Al ₂ O ₃ .

In addition, after removing the oxide generated in the process of dissolving the aluminum ingot by the step (S20) of introducing the first flux to the reflective furnace, a separate flux may be introduced to separate dross in the molten metal surface.

The magnesium-aluminum alloy casting method (S100) of the present invention may further include a step (S25) of reacting by introducing Ti and B into the molten metal after the step of introducing the first flux (S20). Ti may be 20 to 25 ppm, and B may be 20 to 25 ppm.

By introducing Ti and B into the molten metal to react, the size of the aluminum crystal grains becomes 200 to 250 μm, and the crystal grains are refined.

In the step (S30) of charging the AlCa mother alloy in the reflector, charging of the AlCa mother alloy is performed at a temperature of 680 to 700 ° C., and the AlCa mother alloy has a Ca content of 10% and a total content of 350 to 450 ppm in the molten metal. Can be When dissolving Ca, it is preferable to dissolve it by immersing it inside the molten metal so as not to contact oxygen as much as possible.

The magnesium-aluminum alloy casting method (S100) of the present invention, after the step (S30) of charging the AlCa mother alloy to the reflector, the temperature of the 680 to 700 ℃ for 50 to 70 minutes to enable the formation of Al ₄ Ca It may further include the step of maintaining (S35), due to this, to form Al ₄ Ca and a film may be formed. Preferably, the temperature can be maintained for 1 hour.

In the step (S40) of charging the Mg mother alloy to the reflector, while maintaining the temperature of 680 to 700 ° C, charging of the Mg mother alloy is made, and the Mg mother alloy may have a content of 7 to 7.5% in the entire molten metal. At this time, even if the molten metal temperature is lowered so that the oxidation rate of Mg is not accelerated, the temperature is melted without heating. At this time, since the melting point of the alloy decreases with the temperature drop, it may dissolve sufficiently slowly. In the same manner as in dissolving the AlCa mother alloy, it is preferable to submerge the inside of the molten metal so as not to contact oxygen as much as possible.

The magnesium-aluminum alloy casting method (S100) of the present invention, after the step (S40) of charging the Mg mother alloy to the reflector, maintaining the temperature of 680 to 700 ° C. for 50 to 70 minutes (S45) It may further include, Mg is completely decomposed to form a homogeneous equilibrium state. Preferably, the temperature can be maintained for 1 hour.

In the step (S50) of introducing a second flux into the reflection furnace, Cl ₂ may be generated to remove magnesium oxide and calcium oxide by a process reaction. In one example, MgCl ₂ and CaCl ₂ may be formed by generation of Cl ₂ . In addition, the process reaction that may be made by MgCl ₂ and CaCl ₂ may be a MgCl ₂ -KCl-MgO process reaction or a CaCl ₂ -NaCl-CaO process reaction, as illustrated in FIGS. 3 to 6. By this process reaction, the molten metal is melted at a low melting point to remove magnesium oxide and calcium oxide.

For the MgCl ₂ -KCl-MgO process reaction or the CaCl ₂ -NaCl-CaO process reaction, a material containing K or Na or K or Na may be introduced into the reflection furnace.

The magnesium-aluminum alloy casting method (S100) of the present invention may further include a degassing step (S60) performed using nitrogen and SF ₆ gas. For this reason, the molten metal can be made clean and hydrogen gas can be removed.

In addition, the magnesium-aluminum alloy casting method (S100) of the present invention may further include a step (S65) of stabilizing for a predetermined period of time to remove inclusions floating on the surface of the molten metal after the degassing step. The stabilizing step is preferably performed for 40 minutes.

Subsequently, the alloy in the reflecting furnace may be taken at 700 ° C., and may be provided as a mold. Before casting in the mold, the furnace and the hot water can be preheated, and the mold is preferably preheated to 250 to 300 ° C.

The magnesium-aluminum alloy casting method (S100) described above is not limited to the configuration and method of the above-described embodiments, and the embodiments are configured by selectively combining all or part of each embodiment so that various modifications can be made. It may be.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit and essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all respects, but should be considered illustrative. The scope of the invention should be determined by rational interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

S100: magnesium-aluminum alloy casting method
S10: Step of charging and dissolving aluminum ingot in the preheated reflector
S20: Step of injecting the first flux into the reflection path
Step S25: Ti and B are added to the molten metal to react
S30: Step of charging AlCa mother alloy to the reflection furnace
S35: Step to maintain after dissolving AlCa
S40: Step of charging Mg mother alloy to the reflection furnace
S45: Step to maintain after dissolving Mg
S50: Step of injecting the second flux into the reflection path
S60: Degassing step performed using nitrogen and SF ₆ gas

Claims (10)

Charging and dissolving the aluminum ingot in the preheated reflector;
Inputting a first flux into the reflector to remove oxides generated during the dissolution of the aluminum mass;
Charging an AlCa mother alloy to the reflection furnace;
Charging an Mg mother alloy to the reflection furnace;
A method of casting a magnesium-aluminum alloy comprising generating a Cl ₂ and adding a second flux to the reflection furnace to remove magnesium oxide and calcium oxide by a process reaction.
According to claim 1,
Magnesium-aluminum alloy casting method characterized in that it further comprises a degassing step performed using nitrogen and SF ₆ gas to clean the molten metal and to remove hydrogen gas.
According to claim 2,
After the degassing step, magnesium-aluminum alloy casting method further comprises the step of stabilizing for a predetermined time to remove the inclusions floating on the surface of the molten metal.
According to claim 1,
After the step of introducing the first flux, magnesium and aluminum alloy casting method further comprises the step of reacting by introducing Ti and B into the molten metal.
According to claim 4,
The Ti is 20 to 25 ppm, the B is a magnesium-aluminum alloy casting method, characterized in that 20 to 25 ppm.
According to claim 1,
The step of charging the AlCa mother alloy to the reflection furnace,
Charge of the AlCa mother alloy is made at a temperature of 680 to 700 ℃,
Ca content in the AlCa mother alloy is 10%, the AlCa mother alloy, magnesium-aluminum alloy casting method, characterized in that the content of 350 to 450 ppm in the entire molten metal.
The method of claim 6,
After the step of charging the AlCa mother alloy to the reflective furnace, magnesium-aluminum alloy casting further comprising the step of maintaining the temperature of 680 to 700 ℃ for 50 to 70 minutes to enable the formation of Al ₄ Ca Way.
According to claim 1,
The step of charging the Mg mother alloy to the reflection furnace,
Magnesium-aluminum alloy casting method, characterized in that the charging of the Mg mother alloy is made at a temperature of 680 to 700 ° C, and the Mg mother alloy has a content of 7 to 7.5% in the entire molten metal.
The method of claim 8,
After the step of charging the Mg mother alloy to the reflector, characterized in that it further comprises the step of maintaining the temperature of 680 to 700 ℃ for 50 minutes to 70 minutes so that Mg is completely decomposed to form a homogeneous equilibrium state Magnesium-aluminum alloy casting method.
According to claim 1,
The process reaction is MgCl ₂ -KCl-MgO process reaction or CaCl ₂ -NaCl-CaO process reaction, characterized in that the magnesium-aluminum alloy casting method.

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