Aluminum-scandium alloy and method for manufacturing same

Abstract

A method for manufacturing an aluminum-scandium alloy, according to an embodiment of the present invention, comprises the steps of: manufacturing a master alloy ingot of Al-Cu, Al-Mg, Al-Mn, Al-Zn, Al-Ti, and Al-Sc in a nitrogen atmosphere melting furnace at 700-760°C; adding the ingot into the melting furnace at 730-760°C, so that the final components comprise 2.0-4.5 wt% of Cu, 2.0-4.5 wt% of Mg, 0.001-0.05 wt% of Mn, 5.5-10.5 wt% of Zn, 0.002-0.05 wt% of Ti, 0.006-0.03 wt% of Sc, inevitable impurities, and the remaining parts by weight of Al, and stirring the ingot until the hydrogen content of an alloy is 0.12 ml / 100 g or less; homogenizing the internal structure of the stirred alloy at 400-450°C, and aging the alloy in the nitrogen atmosphere melting furnace for 24 hours or longer; extruding and rolling the aged alloy; heating the rolled alloy in a stepwise manner up to 480°C; and quenching the heated alloy from 27°C to -198°C.

Description

[0001] The present invention relates to an aluminum-scandium alloy and a method for manufacturing the same, and more specifically, to an aluminum-scandium alloy with enhanced mechanical strength and elongation, and a method for manufacturing the same.Background Art

[0002] Aluminum alloy materials are light, have good corrosion resistance and processability, have high electrical and thermal conductivity, and are made of elements such as Cu, Mg, Si, Zn, Mn, Ni, etc., to produce various types of alloys with high strength and high corrosion resistance, which are used in all fields of home and industry such as aircraft, household goods, architecture, vehicles, machines, electricity, etc.

[0003] The aluminum alloys are manufactured by melting and casting aluminum ingots and elements for each alloy, which are raw materials, to prepare billets, and are subjected to homogenization heat treatment if necessary, and then the billets are extruded into a predetermined shape.

[0004] Aluminum is classified according to the types of alloy, and a method of classifying aluminum, in which 1000 series represent pure aluminum containing at least 99.00 wt% of aluminum, 2000 series represent an Al-Cu-based alloy, 3000 series represent an Al-Mn-based alloy, 4000 series represent an Al-Si-based alloy, 5000 series represent an Al-Mg-based alloy, 6000 series represent an Al-Mg-Si-based alloy, and 7000 series represent an Al-Zn-based alloy, is widely used.

[0005] Among them, in the case of the aluminum alloy of 7000 series, alloy 7050, in which Cr of alloy 7075 is substituted with Zr has high strength and better stress-resistant corrosion cracking properties and improved quenching properties. There are also alloy 7150 which has better strength by about 10% by improving alloy 7050, alloy 7475 which has improved fracture toughness and fatigue properties by regulating impurities in alloy 7075, alloy 7010 which has improved fracture toughness by slightly reducing an amount of Cu in alloy 7050, and the like. As a casting material, the quenched and tempered Al-1.3% Cu-5% Si-0.5% Mg alloy or Al-7% Si-0.3% Mg alloy may show a tensile strength of 25-35 kg / mm 2< , a durability of 20-25 kg / mm 2< , and an elongation of 1-10%, but in the Al-5% Zn-2% Mg alloy, a material having the tensile strength of 45 kg / mm 2< may be obtained by aging treatment.

[0006] Meanwhile, Korean Unexamined Patent Publication No. 10-2012-0135546 discloses a method for manufacturing a scandium-added aluminum alloy, the method including casting and homogenization-treating an Al-Zn-Mg-Cu-Zr-Ti-Sc alloy, followed by a solution heat treatment step of controlling a recrystallization fraction and an amount of vacancy-cluster produced and increasing elongation, and a natural aging step of precipitating in GP zone while being maintained at room temperature to increase strength.

[0007] In addition, Korean Registered Patent No. 10-0909699 discloses an aluminum alloy containing scandium and having improved impact energy due to beryllium, in which the aluminum alloy has a silicon content of more than 0 and 0.1 or less, an iron content of more than 0 and 0.1 or less, a copper content of 1.5 or more and 2.5 or less, a magnesium content of 1.8 or more and 2.2 or less, a zinc content of 7.6 or more and 8.4 or less, a zirconium content of 0.11 or more and 0.15 or less, a titanium content of 0.02 or more and 0.08 or less, a scandium content of 0.08 or more and 0.12 or less, and a beryllium content of 0.05 or more and 0.1 or less, based on the total weight % of the aluminum alloy.Disclosure Technical Problem

[0008] The present invention may provide an aluminum alloy having excellent strength and elongation and a method for manufacturing the same.Technical Solution

[0009] To solve the above problem, a method for manufacturing an aluminum-scandium alloy according to one embodiment of the present invention may include: preparing a master alloy ingot of Al-Cu, Al-Mg, Al-Mn, Al-Zn, Al-Ti, and Al-Sc in a nitrogen atmosphere melting furnace at 700-760°C; adding the ingot into the melting furnace at 730-760°C, so that the final components include 2.0-4.5 wt% of Cu, 2.0-4.5 wt% of Mg, 0.001-0.05 wt% of Mn, 5.5-10.5 wt% of Zn, 0.002-0.05 wt% of Ti, 0.006-0.03 wt% of Sc, inevitable impurities, and the remaining parts by weight of Al, and stirring the alloy; homogenizing an internal structure of the stirred alloy at 400-450°C, and aging the alloy in the nitrogen atmosphere melting furnace for 24 hours or longer; extracting the aged alloy into an ingot, an extruded material or a rolled material; heating the rolled alloy in a stepwise manner up to 480°C; and quenching the heated alloy to a temperature ranging from 27°C to -198°C, in which the manufactured alloy may include at most 0.1 wt% of Fe and at most 0.12 ml / 100 g of hydrogen as impurities.Advantageous Effects

[0010] An alloy manufactured according to the present invention may have excellent tensile strength, yield strength and elongation, and thus may be expected to be used in various industrial fields.Description of Drawings

[0011] FIG. 1 is a view showing a hydrogen content in an alloy manufactured according to one embodiment of the present invention. FIG. 2 is a view showing a thickness of a chilled layer of an alloy manufactured according to one embodiment of the present invention. FIG. 3 is a view showing a crystal grain size of an alloy manufactured according to one embodiment of the present invention. Best Mode for Invention

[0012] A method for manufacturing an aluminum-scandium alloy according to one embodiment of the present invention may include: preparing a master alloy ingot of Al-Cu, Al-Mg, Al-Mn, Al-Zn, Al-Ti, and Al-Sc in a nitrogen atmosphere melting furnace at 700-760°C; adding the ingot into the melting furnace at 730-760°C, so that the final components include 2.0-4.5 wt% of Cu, 2.0-4.5 wt% of Mg, 0.001-0.05 wt% of Mn, 5.5-10.5 wt% of Zn, 0.002-0.05 wt% of Ti, 0.006-0.03 wt% of Sc, inevitable impurities, and the remaining parts by weight of Al, and stirring the alloy; homogenizing an internal structure of the stirred alloy at 400-450°C, and aging the alloy in the nitrogen atmosphere melting furnace for 24 hours or longer; extracting the aged alloy into an ingot, an extruded material or a rolled material; heating the rolled alloy in a stepwise manner up to 480°C; and quenching the heated alloy to a temperature ranging from 27°C to -198°C, in which the manufactured alloy may include at most 0.1 wt% of Fe and at most 0.12 ml / 100 g of hydrogen as impurities.Mode for Invention

[0013] The present invention may be all implemented by the following description. The following description should be understood as describing preferable embodiments of the present invention, and the present invention is not necessarily limited thereto. In addition, the accompanying drawings are provided to help understanding, and the present invention is not limited thereto, and details of individual configurations may be appropriately understood by the specific purpose of the related description to be described later.

[0014] In the present specification, when a component is referred to as "including," it may mean that other components may be further included unless otherwise stated.

[0015] In addition, in the present specification, the term "located at an upper side" or "located at a lower side" may be understood as expressing a relative positional relationship not only in a state of being in contact with a specific object but also in a state of not being in contact with the specific object.

[0016] "Corrosion" may refer to a destructive phenomenon to which a metal is directly subjected by an electrochemical or chemical reaction in a given environment.

[0017] "Casting" may refer to a process of melting metal in a liquid state in a furnace and then injecting and cooling the molten metal into a mold to manufacture a metal product having a predetermined shape, and may be classified into sand casting (using sand as a mold, which is a consumable material), mold casting, die casting, special casting, and the like.

[0018] "Master alloy" may refer to a primary alloy in which the content of an alloy element is increased by about 10% to 20% in advance in order to suppress non-uniform distribution of the alloy element due to a segregation phenomenon and minimize a loss of expensive alloy elements when the content of the alloy element is small (usually less than 1%).A. Mixing of aluminum-based alloy raw materials

[0019] In the present invention, the aluminum alloy raw material may include aluminum as a main raw material, and may also include copper, magnesium, manganese, zinc, titanium, scandium, or other inevitable impurities. In this case, the raw material may be used in the form of powder, particles, or ingot.

[0020] The present invention may involve preparing a separate master alloy for each element of the alloy, and mixing the same to manufacture a final alloy in the process of manufacturing an aluminum-scandium alloy. After the master alloy for each element is prepared, the alloy may be manufactured in order to ensure uniformity of elements included in a small amount in the final product and to prevent impurities from being generated due to an inter-element reaction.

[0021] Out of the aluminum-based alloy raw materials, scandium (Sc) may make crystal grains of the aluminum-based alloy fine, and thus may increase resistance to high-temperature cracking and have an effect on securing strength and elongation of the alloy. When scandium is excessively added, physical properties may be deteriorated due to undissolved Sc segregation. Considering the above, in the present invention, an amount of scandium (Sc) in the alloy raw materials may be adjusted within a range of 0.001 to 1 wt%, specifically about 0.003 to 0.5 wt%, and more specifically 0.006 to 0.1 wt%.

[0022] Hydrogen may be generated during the casting process, and may be included in the alloy to create gas porosity, expand to coagulation shrinkage defects and reduce fatigue strength. Accordingly, there has been ongoing research to reduce a hydrogen content in the alloy. In the present invention, the amount of hydrogen in the alloy raw materials may be adjusted within the range of 0.12 ml / 100 g or less, more specifically 0.09 ml / 100 g.

[0023] Iron (Fe) may be introduced as an impurity in the process of manufacturing the alloy. As the content of iron increases, the tensile strength of the alloy may decrease and thus it may be important to manufacture the alloy by minimizing the content of iron. The alloy manufactured according to the manufacturing method of the present invention may contain 0.1 wt% or less of Fe.B. Method for manufacturing an aluminum-scandium alloy

[0024] A method for manufacturing an aluminum-scandium alloy according to one embodiment of the present invention may include preparing a master alloy ingot, stirring, aging, extruding and rolling, heating, and quenching.

[0025] The preparing of the master alloy ingot may refer to preparing a master alloy of Al-Cu, Al-Mg, Al-Mn, Al-Zn, Al-Ti, Al-Sc. This may refer to preparing a separate master alloy for each element in order to increase the uniformity of metal in the aluminum alloy.

[0026] The nitrogen atmosphere melting furnace may refer to a furnace filled with nitrogen in order to prevent the molten metal from being exposed to atmosphere.

[0027] More specifically, the preparing of the aluminum-copper master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-750°C, removing a floating slug thereon, and adding copper. In this case, aluminum and copper may be mixed in the nitrogen atmosphere melting furnace for 10 hours or more and less than 30 hours. The aluminum-copper master alloy ingot may be prepared such that the copper content may reach 5 to 15 wt%.

[0028] The preparing of the aluminum-magnesium master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-750°C, removing a floating slug thereon, and adding magnesium. In this case, aluminum and magnesium may be mixed in the nitrogen atmosphere melting furnace for 10 hours or more and less than 30 hours. The aluminum-magnesium master alloy ingot may be prepared such that the magnesium content may reach 5 to 15 wt%.

[0029] The preparing of the aluminum-manganese master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-770°C, removing a floating slug thereon, and adding manganese. In this case, aluminum and manganese may be mixed in the nitrogen atmosphere melting furnace for 10 hours or more and less than 30 hours. The aluminum-manganese master alloy ingot may be prepared such that the manganese content may reach 5 to 15 wt%.

[0030] The preparing of the aluminum-zinc master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-750°C, removing a floating slug thereon, and adding zinc. In this case, aluminum and zinc may be mixed in the nitrogen atmosphere melting furnace for 10 hours or more and less than 30 hours. The aluminum-zinc master alloy ingot may be prepared such that the zinc content may reach 15 to 25 wt%.

[0031] The preparing of the aluminum-titanium master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-750°C, removing a floating slug thereon, and adding titanium. In this case, aluminum and titanium may be mixed in the nitrogen atmosphere melting furnace for 10 hours or more and less than 30 hours. The aluminum-titanium master alloy ingot may be prepared such that the titanium content may reach 1 to 10 wt%.

[0032] The preparing of the aluminum-scandium master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-770°C, removing a floating slug thereon, and adding scandium. In this case, aluminum and scandium may be mixed in the nitrogen atmosphere melting furnace for 30 hours or more and less than 50 hours. The aluminum-scandium master alloy ingot may be prepared such that the scandium content may reach 1 to 5 wt%.

[0033] The preparing of the master alloy may be performed in a sealed nitrogen container to reduce an amount of dissolved hydrogen in the alloy, and may be accompanied by a process of degassing, filling with nitrogen, and maintaining the temperature at 730-760°C for 10 to 30 hours in order to remove segregation of a secondary alloy.

[0034] The stirring may refer to a process of adding the master alloy so that the element in the aluminum alloy may have a desired ratio after the master alloy ingot is prepared, and stirring the master alloy. The stirring process may refer to a process of adding aluminum having a purity of 85-99.5% to the melting furnace at 730-760°C, and then adding a copper master alloy, a magnesium master alloy, a zinc master alloy, a manganese master alloy, and a scandium master alloy at regular time intervals to manufacture the alloy so that the final components of the alloy may include 2.0-4.5 wt% of Cu, 2.0-4.5 wt% of Mg, 0.001-0.05 wt% of Mn, 5.5-10.5 wt% of Zn, 0.002-0.05 wt% of Ti, 0.006-0.03 wt% of Sc, inevitable impurities, and the remaining parts by weight of Al. If necessary, the final components of the alloy may include 2.0-2.5 wt% of Cu, 2.0-2.5 wt% of Mg, 0.001-0.05 wt% of Mn, 7-9 wt% of Zn, 0.002-0.05 wt% of Ti, and 0.006-0.03 wt% of Sc.

[0035] In addition, the stirring may be performed until the hydrogen content of the alloy reaches 0.12 ml / 100 g or less. If the hydrogen content of the alloy exceeds 0.12 ml / 100 g in the stirring process, a process of removing hydrogen may be included. If necessary, the alloy may be stirred until the hydrogen content of the alloy reaches 0.09 ml / 100 g or less.

[0036] In addition, the impurities may include 0.1 wt% or less of iron. When the content of iron is increased, it may affect the mechanical properties of the alloy, and thus the content of iron in impurities may be limited when preparing the master alloy so that the content of iron in the impurities may reach 0.1 wt% or less.

[0037] The aging may refer to aging at a certain temperature for a predetermined time for internal homogenization of the stirred alloy. According to the present invention, the stirred alloy may be aged in a nitrogen atmosphere melting furnace at 400-450°C for 24 hours or more.

[0038] The extracting may refer to extracting the aged alloy into an ingot, an extruded material or a rolled material. Extrusion, rolling, and extraction techniques may follow known techniques, and thus detailed descriptions thereof will be omitted.

[0039] The heating may refer to heating the rolled alloy in a stepwise manner up to 480°C. This may be a heat treatment method for recombining dualized microstructures. If necessary, the heating may be carried out in six to ten stages. The alloy at room temperature may be heated to 480°C sequentially through 50°C, 80°C, 100°C, 150°C, 200°C, 300°C, and 400°C, and may be maintained at each temperature for one hour to 24 hours.

[0040] The quenching may refer to quenching the heated alloy to a temperature ranging from 27°C to -198°C. The quenching may be a process of strengthening toughness by quenching a cast product which has undergone the heating at a cooling rate of 100°C / sec or more. A method of quenching may use liquefied nitrogen or water, which is a commonly used method. Usually, aluminum and an alloy containing aluminum may not be quenched, but slowly cooled. However, in the case of the aluminum-scandium alloy according to the present invention, a segregation phenomenon may rapidly occur due to a rapid movement speed of scandium in grains and grain boundaries, and thus a quenching process may be required to suppress the segregation phenomenon. When the alloy is quenched, scandium and magnesium elements may not be segregated at grain boundaries, but uniformly distributed in grains, thereby minimizing an intergranular brittle fracture phenomenon and micro-crack generation and increasing toughness and tensile strength. Here, the intergranular brittle fracture phenomenon may mean a low temperature brittle fracture generated by segregation of impurities on the grain boundary.

[0041] According to one embodiment, the alloy manufactured according to the present invention may have a value of (Mn + Ti + Fe) / Sc of 5.25 or less. When the value of (Mn + Ti + Fe) / Sc exceeds 5.25, the tensile strength and the yield strength may be rapidly deteriorated. In the case of the alloy manufactured according to the present invention, it can be confirmed in Table 2 that the alloy exhibits excellent tensile strength of 700 N / mm 2< or more. Among the alloys manufactured, samples A and B may be alloys having a value of (Mn + Ti + Fe) / Sc of 5.25 or less, exhibit excellent tensile strength of 700 N / mm 2< or more, and have excellent yield strength of 650 N / mm 2< or more.Example

[0042] The tensile strength, yield strength, and elongation of the alloy obtained from the present example were measured using an ASTM E8 / E8M-21. [Table 1]Element contentCuMgMnZnTiScFeSample A2.0022.0560.0017.4990.0050.0190.072Sample B2.352.230.0019.090.00520.0130.062Sample C1.011.720.00276.460.00480.010.17 [Table 2] Tensile strength, yield strength and elongationSample classification(Mn+Ti+Fe) / ScTensile strength (N / mm 2< )Yield strength (0.2% offset, (N / mm 2< ))Elongation (%)Sample A4.1170768510Sample B5.2571267112Sample C17.7550246417

[0043] According to one embodiment, the quenched alloy, which has undergone the quenching process, may have an average crystal grain size of more than 100 µm and less than 200 µm. As the quenching is performed, fine crystal grains may be generated in the alloy, which may have a positive effect on tensile strength.

[0044] In addition, a chilled layer generated in the quenched alloy may be less than 1 mm. The thickness of the chilled layer may be affected by the cooling rate.

[0045] According to one embodiment of the present invention, a surface of the alloy, which has undergone the quenching process, may have a microstructure of a dendritic-like structure. In addition, the alloy manufactured according to an embodiment of the present invention may have the tensile strength of 650 N / mm 2< or more, the elongation of 10% or more, and the yield strength of 600 N / mm 2< or more.

[0046] According to another embodiment of the present invention, the aluminum-scandium alloy according to the present invention may include 2.0-4.5 wt% of Cu, 2.0-4.5 wt% of Mg, 0.001-0.05 wt% of Mn, 5.5-10.5 wt% of Zn, 0.002-0.05 wt% of Ti, 0.006-0.03 wt% of Sc, inevitable impurities, and the remaining parts by weight of Al. If necessary, the final components of the alloy may include 2.0-2.5 wt% of Cu, 2.0-2.5 wt% of Mg, 0.001-0.05 wt% of Mn, 7-9 wt% of Zn, 0.002-0.05 wt% of Ti, and 0.006-0.03 wt% of Sc.

[0047] In addition, the impurities of the alloy according to the present invention may include at most 0.1 wt% of Fe and at most 0.12 ml / 100 g of hydrogen. In addition, the alloy according to the present invention may have a value of (Mn + Ti + Fe) / Sc that does not exceed 5.25, and may have excellent tensile strength and yield strength. The alloy manufactured according to the present invention may have the tensile strength of 650 N / mm 2< or more, the elongation of 10% or more, and the yield strength of 600 N / mm 2< or more. If necessary, the alloy satisfying the above formula may exhibit the excellent tensile strength of 700 N / mm 2< or more and may have the excellent yield strength of 650 N / mm 2< or more.

[0048] In addition, the alloy according to the present invention may have an average crystal grain size of more than 100 µm and less than 200 µm.

[0049] The aluminum-scandium alloy manufactured according to the present invention may have excellent tensile strength, yield strength and elongation, and thus may be expected to be used in various industrial fields in the future.

[0050] Although the present invention has been described in detail above, the present invention is not limited to the above-described contents, and may be variously modified and implemented without departing from the technical spirit of the present invention. Thus, the above description is not intended to limit the technical spirit of the present invention, but to explain the present invention. Accordingly, the scope of protection of the present invention should be interpreted by the claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

Examples

example

[0042]The tensile strength, yield strength, and elongation of the alloy obtained from the present example were measured using an ASTM E8 / E8M-21.

[Table 1]

Element content

CuMgMnZnTiScFe

Sample A2.0022.0560.0017.4990.0050.0190.072

Sample B2.352.230.0019.090.00520.0130.062

Sample C1.011.720.00276.460.00480.010.17

[Table 2] Tensile strength, yield strength and elongationSample classification(Mn+Ti+Fe) / ScTensile strength (N / mm 2Yield strength (0.2% offset, (N / mm 2Elongation (%)Sample A4.1170768510Sample B5.2571267112Sample C17.7550246417

[0043] According to one embodiment, the quenched alloy, which has undergone the quenching process, may have an average crystal grain size of more than 100 µm and less than 200 µm. As the quenching is performed, fine crystal grains may be generated in the alloy, which may have a positive effect on tensile strength.

[0044]In addition, a chilled layer generated in the quenched alloy may be less than 1 mm. The thickness of the chilled layer...

[0001] The present invention relates to an aluminum-scandium alloy and a method for manufacturing the same, and more specifically, to an aluminum-scandium alloy with enhanced mechanical strength and elongation, and a method for manufacturing the same.Background Art

[0002] Aluminum alloy materials are light, have good corrosion resistance and processability, have high electrical and thermal conductivity, and are made of elements such as Cu, Mg, Si, Zn, Mn, Ni, etc., to produce various types of alloys with high strength and high corrosion resistance, which are used in all fields of home and industry such as aircraft, household goods, architecture, vehicles, machines, electricity, etc.

[0003] The aluminum alloys are manufactured by melting and casting aluminum ingots and elements for each alloy, which are raw materials, to prepare billets, and are subjected to homogenization heat treatment if necessary, and then the billets are extruded into a predetermined shape.

[0004] Aluminum is classified according to the types of alloy, and a method of classifying aluminum, in which 1000 series represent pure aluminum containing at least 99.00 wt% of aluminum, 2000 series represent an Al-Cu-based alloy, 3000 series represent an Al-Mn-based alloy, 4000 series represent an Al-Si-based alloy, 5000 series represent an Al-Mg-based alloy, 6000 series represent an Al-Mg-Si-based alloy, and 7000 series represent an Al-Zn-based alloy, is widely used.

[0005] Among them, in the case of the aluminum alloy of 7000 series, alloy 7050, in which Cr of alloy 7075 is substituted with Zr has high strength and better stress-resistant corrosion cracking properties and improved quenching properties. There are also alloy 7150 which has better strength by about 10% by improving alloy 7050, alloy 7475 which has improved fracture toughness and fatigue properties by regulating impurities in alloy 7075, alloy 7010 which has improved fracture toughness by slightly reducing an amount of Cu in alloy 7050, and the like. As a casting material, the quenched and tempered Al-1.3% Cu-5% Si-0.5% Mg alloy or Al-7% Si-0.3% Mg alloy may show a tensile strength of 25-35 kg / mm 2< , a durability of 20-25 kg / mm 2< , and an elongation of 1-10%, but in the Al-5% Zn-2% Mg alloy, a material having the tensile strength of 45 kg / mm 2< may be obtained by aging treatment.

[0006] Meanwhile, Korean Unexamined Patent Publication No. 10-2012-0135546 discloses a method for manufacturing a scandium-added aluminum alloy, the method including casting and homogenization-treating an Al-Zn-Mg-Cu-Zr-Ti-Sc alloy, followed by a solution heat treatment step of controlling a recrystallization fraction and an amount of vacancy-cluster produced and increasing elongation, and a natural aging step of precipitating in GP zone while being maintained at room temperature to increase strength.

[0007] In addition, Korean Registered Patent No. 10-0909699 discloses an aluminum alloy containing scandium and having improved impact energy due to beryllium, in which the aluminum alloy has a silicon content of more than 0 and 0.1 or less, an iron content of more than 0 and 0.1 or less, a copper content of 1.5 or more and 2.5 or less, a magnesium content of 1.8 or more and 2.2 or less, a zinc content of 7.6 or more and 8.4 or less, a zirconium content of 0.11 or more and 0.15 or less, a titanium content of 0.02 or more and 0.08 or less, a scandium content of 0.08 or more and 0.12 or less, and a beryllium content of 0.05 or more and 0.1 or less, based on the total weight % of the aluminum alloy.Disclosure Technical Problem

[0008] The present invention may provide an aluminum alloy having excellent strength and elongation and a method for manufacturing the same.Technical Solution

[0009] To solve the above problem, a method for manufacturing an aluminum-scandium alloy according to one embodiment of the present invention may include: preparing a master alloy ingot of Al-Cu, Al-Mg, Al-Mn, Al-Zn, Al-Ti, and Al-Sc in a nitrogen atmosphere melting furnace at 700-760°C; adding the ingot into the melting furnace at 730-760°C, so that the final components include 2.0-4.5 wt% of Cu, 2.0-4.5 wt% of Mg, 0.001-0.05 wt% of Mn, 5.5-10.5 wt% of Zn, 0.002-0.05 wt% of Ti, 0.006-0.03 wt% of Sc, inevitable impurities, and the remaining parts by weight of Al, and stirring the alloy; homogenizing an internal structure of the stirred alloy at 400-450°C, and aging the alloy in the nitrogen atmosphere melting furnace for 24 hours or longer; extracting the aged alloy into an ingot, an extruded material or a rolled material; heating the rolled alloy in a stepwise manner up to 480°C; and quenching the heated alloy to a temperature ranging from 27°C to -198°C, in which the manufactured alloy may include at most 0.1 wt% of Fe and at most 0.12 ml / 100 g of hydrogen as impurities.Advantageous Effects

[0010] An alloy manufactured according to the present invention may have excellent tensile strength, yield strength and elongation, and thus may be expected to be used in various industrial fields.Description of Drawings

[0011] FIG. 1 is a view showing a hydrogen content in an alloy manufactured according to one embodiment of the present invention. FIG. 2 is a view showing a thickness of a chilled layer of an alloy manufactured according to one embodiment of the present invention. FIG. 3 is a view showing a crystal grain size of an alloy manufactured according to one embodiment of the present invention. Best Mode for Invention

[0012] A method for manufacturing an aluminum-scandium alloy according to one embodiment of the present invention may include: preparing a master alloy ingot of Al-Cu, Al-Mg, Al-Mn, Al-Zn, Al-Ti, and Al-Sc in a nitrogen atmosphere melting furnace at 700-760°C; adding the ingot into the melting furnace at 730-760°C, so that the final components include 2.0-4.5 wt% of Cu, 2.0-4.5 wt% of Mg, 0.001-0.05 wt% of Mn, 5.5-10.5 wt% of Zn, 0.002-0.05 wt% of Ti, 0.006-0.03 wt% of Sc, inevitable impurities, and the remaining parts by weight of Al, and stirring the alloy; homogenizing an internal structure of the stirred alloy at 400-450°C, and aging the alloy in the nitrogen atmosphere melting furnace for 24 hours or longer; extracting the aged alloy into an ingot, an extruded material or a rolled material; heating the rolled alloy in a stepwise manner up to 480°C; and quenching the heated alloy to a temperature ranging from 27°C to -198°C, in which the manufactured alloy may include at most 0.1 wt% of Fe and at most 0.12 ml / 100 g of hydrogen as impurities.Mode for Invention

[0013] The present invention may be all implemented by the following description. The following description should be understood as describing preferable embodiments of the present invention, and the present invention is not necessarily limited thereto. In addition, the accompanying drawings are provided to help understanding, and the present invention is not limited thereto, and details of individual configurations may be appropriately understood by the specific purpose of the related description to be described later.

[0014] In the present specification, when a component is referred to as "including," it may mean that other components may be further included unless otherwise stated.

[0015] In addition, in the present specification, the term "located at an upper side" or "located at a lower side" may be understood as expressing a relative positional relationship not only in a state of being in contact with a specific object but also in a state of not being in contact with the specific object.

[0016] "Corrosion" may refer to a destructive phenomenon to which a metal is directly subjected by an electrochemical or chemical reaction in a given environment.

[0017] "Casting" may refer to a process of melting metal in a liquid state in a furnace and then injecting and cooling the molten metal into a mold to manufacture a metal product having a predetermined shape, and may be classified into sand casting (using sand as a mold, which is a consumable material), mold casting, die casting, special casting, and the like.

[0018] "Master alloy" may refer to a primary alloy in which the content of an alloy element is increased by about 10% to 20% in advance in order to suppress non-uniform distribution of the alloy element due to a segregation phenomenon and minimize a loss of expensive alloy elements when the content of the alloy element is small (usually less than 1%).A. Mixing of aluminum-based alloy raw materials

[0019] In the present invention, the aluminum alloy raw material may include aluminum as a main raw material, and may also include copper, magnesium, manganese, zinc, titanium, scandium, or other inevitable impurities. In this case, the raw material may be used in the form of powder, particles, or ingot.

[0020] The present invention may involve preparing a separate master alloy for each element of the alloy, and mixing the same to manufacture a final alloy in the process of manufacturing an aluminum-scandium alloy. After the master alloy for each element is prepared, the alloy may be manufactured in order to ensure uniformity of elements included in a small amount in the final product and to prevent impurities from being generated due to an inter-element reaction.

[0021] Out of the aluminum-based alloy raw materials, scandium (Sc) may make crystal grains of the aluminum-based alloy fine, and thus may increase resistance to high-temperature cracking and have an effect on securing strength and elongation of the alloy. When scandium is excessively added, physical properties may be deteriorated due to undissolved Sc segregation. Considering the above, in the present invention, an amount of scandium (Sc) in the alloy raw materials may be adjusted within a range of 0.001 to 1 wt%, specifically about 0.003 to 0.5 wt%, and more specifically 0.006 to 0.1 wt%.

[0022] Hydrogen may be generated during the casting process, and may be included in the alloy to create gas porosity, expand to coagulation shrinkage defects and reduce fatigue strength. Accordingly, there has been ongoing research to reduce a hydrogen content in the alloy. In the present invention, the amount of hydrogen in the alloy raw materials may be adjusted within the range of 0.12 ml / 100 g or less, more specifically 0.09 ml / 100 g.

[0023] Iron (Fe) may be introduced as an impurity in the process of manufacturing the alloy. As the content of iron increases, the tensile strength of the alloy may decrease and thus it may be important to manufacture the alloy by minimizing the content of iron. The alloy manufactured according to the manufacturing method of the present invention may contain 0.1 wt% or less of Fe.B. Method for manufacturing an aluminum-scandium alloy

[0024] A method for manufacturing an aluminum-scandium alloy according to one embodiment of the present invention may include preparing a master alloy ingot, stirring, aging, extruding and rolling, heating, and quenching.

[0025] The preparing of the master alloy ingot may refer to preparing a master alloy of Al-Cu, Al-Mg, Al-Mn, Al-Zn, Al-Ti, Al-Sc. This may refer to preparing a separate master alloy for each element in order to increase the uniformity of metal in the aluminum alloy.

[0026] The nitrogen atmosphere melting furnace may refer to a furnace filled with nitrogen in order to prevent the molten metal from being exposed to atmosphere.

[0027] More specifically, the preparing of the aluminum-copper master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-750°C, removing a floating slug thereon, and adding copper. In this case, aluminum and copper may be mixed in the nitrogen atmosphere melting furnace for 10 hours or more and less than 30 hours. The aluminum-copper master alloy ingot may be prepared such that the copper content may reach 5 to 15 wt%.

[0028] The preparing of the aluminum-magnesium master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-750°C, removing a floating slug thereon, and adding magnesium. In this case, aluminum and magnesium may be mixed in the nitrogen atmosphere melting furnace for 10 hours or more and less than 30 hours. The aluminum-magnesium master alloy ingot may be prepared such that the magnesium content may reach 5 to 15 wt%.

[0029] The preparing of the aluminum-manganese master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-770°C, removing a floating slug thereon, and adding manganese. In this case, aluminum and manganese may be mixed in the nitrogen atmosphere melting furnace for 10 hours or more and less than 30 hours. The aluminum-manganese master alloy ingot may be prepared such that the manganese content may reach 5 to 15 wt%.

[0030] The preparing of the aluminum-zinc master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-750°C, removing a floating slug thereon, and adding zinc. In this case, aluminum and zinc may be mixed in the nitrogen atmosphere melting furnace for 10 hours or more and less than 30 hours. The aluminum-zinc master alloy ingot may be prepared such that the zinc content may reach 15 to 25 wt%.

[0031] The preparing of the aluminum-titanium master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-750°C, removing a floating slug thereon, and adding titanium. In this case, aluminum and titanium may be mixed in the nitrogen atmosphere melting furnace for 10 hours or more and less than 30 hours. The aluminum-titanium master alloy ingot may be prepared such that the titanium content may reach 1 to 10 wt%.

[0032] The preparing of the aluminum-scandium master alloy ingot may be performed by adding aluminum having a purity of 98-99.5% in the nitrogen atmosphere melting furnace, maintaining the same at 700-770°C, removing a floating slug thereon, and adding scandium. In this case, aluminum and scandium may be mixed in the nitrogen atmosphere melting furnace for 30 hours or more and less than 50 hours. The aluminum-scandium master alloy ingot may be prepared such that the scandium content may reach 1 to 5 wt%.

[0033] The preparing of the master alloy may be performed in a sealed nitrogen container to reduce an amount of dissolved hydrogen in the alloy, and may be accompanied by a process of degassing, filling with nitrogen, and maintaining the temperature at 730-760°C for 10 to 30 hours in order to remove segregation of a secondary alloy.

[0034] The stirring may refer to a process of adding the master alloy so that the element in the aluminum alloy may have a desired ratio after the master alloy ingot is prepared, and stirring the master alloy. The stirring process may refer to a process of adding aluminum having a purity of 85-99.5% to the melting furnace at 730-760°C, and then adding a copper master alloy, a magnesium master alloy, a zinc master alloy, a manganese master alloy, and a scandium master alloy at regular time intervals to manufacture the alloy so that the final components of the alloy may include 2.0-4.5 wt% of Cu, 2.0-4.5 wt% of Mg, 0.001-0.05 wt% of Mn, 5.5-10.5 wt% of Zn, 0.002-0.05 wt% of Ti, 0.006-0.03 wt% of Sc, inevitable impurities, and the remaining parts by weight of Al. If necessary, the final components of the alloy may include 2.0-2.5 wt% of Cu, 2.0-2.5 wt% of Mg, 0.001-0.05 wt% of Mn, 7-9 wt% of Zn, 0.002-0.05 wt% of Ti, and 0.006-0.03 wt% of Sc.

[0035] In addition, the stirring may be performed until the hydrogen content of the alloy reaches 0.12 ml / 100 g or less. If the hydrogen content of the alloy exceeds 0.12 ml / 100 g in the stirring process, a process of removing hydrogen may be included. If necessary, the alloy may be stirred until the hydrogen content of the alloy reaches 0.09 ml / 100 g or less.

[0036] In addition, the impurities may include 0.1 wt% or less of iron. When the content of iron is increased, it may affect the mechanical properties of the alloy, and thus the content of iron in impurities may be limited when preparing the master alloy so that the content of iron in the impurities may reach 0.1 wt% or less.

[0037] The aging may refer to aging at a certain temperature for a predetermined time for internal homogenization of the stirred alloy. According to the present invention, the stirred alloy may be aged in a nitrogen atmosphere melting furnace at 400-450°C for 24 hours or more.

[0038] The extracting may refer to extracting the aged alloy into an ingot, an extruded material or a rolled material. Extrusion, rolling, and extraction techniques may follow known techniques, and thus detailed descriptions thereof will be omitted.

[0039] The heating may refer to heating the rolled alloy in a stepwise manner up to 480°C. This may be a heat treatment method for recombining dualized microstructures. If necessary, the heating may be carried out in six to ten stages. The alloy at room temperature may be heated to 480°C sequentially through 50°C, 80°C, 100°C, 150°C, 200°C, 300°C, and 400°C, and may be maintained at each temperature for one hour to 24 hours.

[0040] The quenching may refer to quenching the heated alloy to a temperature ranging from 27°C to -198°C. The quenching may be a process of strengthening toughness by quenching a cast product which has undergone the heating at a cooling rate of 100°C / sec or more. A method of quenching may use liquefied nitrogen or water, which is a commonly used method. Usually, aluminum and an alloy containing aluminum may not be quenched, but slowly cooled. However, in the case of the aluminum-scandium alloy according to the present invention, a segregation phenomenon may rapidly occur due to a rapid movement speed of scandium in grains and grain boundaries, and thus a quenching process may be required to suppress the segregation phenomenon. When the alloy is quenched, scandium and magnesium elements may not be segregated at grain boundaries, but uniformly distributed in grains, thereby minimizing an intergranular brittle fracture phenomenon and micro-crack generation and increasing toughness and tensile strength. Here, the intergranular brittle fracture phenomenon may mean a low temperature brittle fracture generated by segregation of impurities on the grain boundary.

[0041] According to one embodiment, the alloy manufactured according to the present invention may have a value of (Mn + Ti + Fe) / Sc of 5.25 or less. When the value of (Mn + Ti + Fe) / Sc exceeds 5.25, the tensile strength and the yield strength may be rapidly deteriorated. In the case of the alloy manufactured according to the present invention, it can be confirmed in Table 2 that the alloy exhibits excellent tensile strength of 700 N / mm 2< or more. Among the alloys manufactured, samples A and B may be alloys having a value of (Mn + Ti + Fe) / Sc of 5.25 or less, exhibit excellent tensile strength of 700 N / mm 2< or more, and have excellent yield strength of 650 N / mm 2< or more.Example

[0042] The tensile strength, yield strength, and elongation of the alloy obtained from the present example were measured using an ASTM E8 / E8M-21. [Table 1]Element contentCuMgMnZnTiScFeSample A2.0022.0560.0017.4990.0050.0190.072Sample B2.352.230.0019.090.00520.0130.062Sample C1.011.720.00276.460.00480.010.17 [Table 2] Tensile strength, yield strength and elongationSample classification(Mn+Ti+Fe) / ScTensile strength (N / mm 2< )Yield strength (0.2% offset, (N / mm 2< ))Elongation (%)Sample A4.1170768510Sample B5.2571267112Sample C17.7550246417

[0043] According to one embodiment, the quenched alloy, which has undergone the quenching process, may have an average crystal grain size of more than 100 µm and less than 200 µm. As the quenching is performed, fine crystal grains may be generated in the alloy, which may have a positive effect on tensile strength.

[0044] In addition, a chilled layer generated in the quenched alloy may be less than 1 mm. The thickness of the chilled layer may be affected by the cooling rate.

[0045] According to one embodiment of the present invention, a surface of the alloy, which has undergone the quenching process, may have a microstructure of a dendritic-like structure. In addition, the alloy manufactured according to an embodiment of the present invention may have the tensile strength of 650 N / mm 2< or more, the elongation of 10% or more, and the yield strength of 600 N / mm 2< or more.

[0046] According to another embodiment of the present invention, the aluminum-scandium alloy according to the present invention may include 2.0-4.5 wt% of Cu, 2.0-4.5 wt% of Mg, 0.001-0.05 wt% of Mn, 5.5-10.5 wt% of Zn, 0.002-0.05 wt% of Ti, 0.006-0.03 wt% of Sc, inevitable impurities, and the remaining parts by weight of Al. If necessary, the final components of the alloy may include 2.0-2.5 wt% of Cu, 2.0-2.5 wt% of Mg, 0.001-0.05 wt% of Mn, 7-9 wt% of Zn, 0.002-0.05 wt% of Ti, and 0.006-0.03 wt% of Sc.

[0047] In addition, the impurities of the alloy according to the present invention may include at most 0.1 wt% of Fe and at most 0.12 ml / 100 g of hydrogen. In addition, the alloy according to the present invention may have a value of (Mn + Ti + Fe) / Sc that does not exceed 5.25, and may have excellent tensile strength and yield strength. The alloy manufactured according to the present invention may have the tensile strength of 650 N / mm 2< or more, the elongation of 10% or more, and the yield strength of 600 N / mm 2< or more. If necessary, the alloy satisfying the above formula may exhibit the excellent tensile strength of 700 N / mm 2< or more and may have the excellent yield strength of 650 N / mm 2< or more.

[0048] In addition, the alloy according to the present invention may have an average crystal grain size of more than 100 µm and less than 200 µm.

[0049] The aluminum-scandium alloy manufactured according to the present invention may have excellent tensile strength, yield strength and elongation, and thus may be expected to be used in various industrial fields in the future.

[0050] Although the present invention has been described in detail above, the present invention is not limited to the above-described contents, and may be variously modified and implemented without departing from the technical spirit of the present invention. Thus, the above description is not intended to limit the technical spirit of the present invention, but to explain the present invention. Accordingly, the scope of protection of the present invention should be interpreted by the claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

Examples

example

[0042]The tensile strength, yield strength, and elongation of the alloy obtained from the present example were measured using an ASTM E8 / E8M-21.

[Table 1]

Element content

CuMgMnZnTiScFe

Sample A2.0022.0560.0017.4990.0050.0190.072

Sample B2.352.230.0019.090.00520.0130.062

Sample C1.011.720.00276.460.00480.010.17

[Table 2] Tensile strength, yield strength and elongationSample classification(Mn+Ti+Fe) / ScTensile strength (N / mm 2Yield strength (0.2% offset, (N / mm 2Elongation (%)Sample A4.1170768510Sample B5.2571267112Sample C17.7550246417

[0043] According to one embodiment, the quenched alloy, which has undergone the quenching process, may have an average crystal grain size of more than 100 µm and less than 200 µm. As the quenching is performed, fine crystal grains may be generated in the alloy, which may have a positive effect on tensile strength.

[0044]In addition, a chilled layer generated in the quenched alloy may be less than 1 mm. The thickness of the chilled layer...

Claims

1. A method for manufacturing an aluminum-scandium alloy, the method comprising: preparing a master alloy ingot of Al-Cu, Al-Mg, Al-Mn, Al-Zn, Al-Ti, and Al-Sc in a nitrogen atmosphere melting furnace at 700-760°C; adding the ingot into the melting furnace at 730-760°C, so that final components include 2.0-4.5 wt% of Cu, 2.0-4.5 wt% of Mg, 0.001-0.05 wt% of Mn, 5.5-10.5 wt% of Zn, 0.002-0.05 wt% of Ti, 0.006-0.03 wt% of Sc, inevitable impurities, and remaining parts by weight of Al, and stirring the alloy; homogenizing an internal structure of the stirred alloy at 400-450°C, and aging the alloy in the nitrogen atmosphere melting furnace for 24 hours or longer; extracting the aged alloy into an ingot, an extruded material or a rolled material; heating the extracted alloy in a stepwise manner up to 480°C; and quenching the heated alloy to a temperature ranging from 27°C to -198°C, wherein the impurities include at most 0.1 wt% of Fe and at most 0.12 ml / 100 g of hydrogen.

2. The method of claim 1, wherein the manufactured alloy has a value of (Mn + Ti + Fe) / Sc that does not exceed 5.25.

3. The method of claim 1, wherein the quenched alloy has an average crystal grain size of more than 100 µm and less than 200 µm.

4. The method of claim 3, wherein a chilled layer generated in the quenched alloy is less than 1 mm.

5. The method of claim 4, wherein a surface of the quenched alloy has a dendritic-like microstructure.

6. The method of claim 5, wherein the manufactured alloy has a tensile strength of 650 N / mm2 or more.

7. The method of claim 6, wherein the manufactured alloy has an elongation of 10% or more.

8. The method of claim 7, wherein the manufactured alloy has a yield strength of 600 N / mm2 or more.

9. An aluminum-scandium alloy comprising 2.0-4.5 wt% of Cu, 2.0-4.5 wt% of Mg, 0.001-0.05 wt% of Mn, 5.5-10.5 wt% of Zn, 0.002-0.05 wt% of Ti, 0.006-0.03 wt% of Sc, inevitable impurities, and remaining parts by weight of Al, wherein the impurities of the alloy include at most 0.1 wt% of Fe and at most 0.12 ml / 100 g of hydrogen, wherein the alloy has a value of (Mn + Ti + Fe) / Sc that does not exceed 5.25.

10. The aluminum-scandium alloy of claim 9, wherein the alloy has a tensile strength of 650 N / mm2 or more, an elongation of 10% or more, and a yield strength of 600 N / mm2 or more.

11. The aluminum-scandium alloy of claim 10, wherein the alloy has an average crystal grain size of more than 100 µm and less than 200 µm.

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