Aluminum-scandium alloy and method for producing same

Abstract

A method for producing an aluminum-scandium alloy, according to one embodiment of the present invention, comprises: a step for producing 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 DEG C; a step of adding and stirring the ingot in a smelting furnace at 730 to 760 DEG C so that the final components Cu are 2.0 to 4.5 wt%, Mg are 2.0 to 4.5 wt%, Mn is 0.001 to 0.05 wt%, Zn is 5.5 to 10.5 wt%, Ti is 0.002 to 0.05 wt%, Sc is 0.006 to 0.03 wt%, unavoidable impurities and the remainder are Al; a curing step in which the internal structure of the stirred alloy is homogenized at 400-450 DEG C, and the alloy is cured for 24 hours or more in a nitrogen atmosphere furnace; extruding the cured alloy into a cast ingot, an extruded piece or a rolled piece; a step of gradually heating the extruded alloy to 480 DEG C; and a step of rapidly cooling the heated alloy to a temperature between 27 DEG C and-198 DEG C.

Description

Technical Field

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

[0002] Aluminum alloy materials are light in weight, have good corrosion resistance and processability, and high electrical and thermal conductivity. They can be made into a variety of high-strength, high-corrosion-resistant alloys with elements such as Cu, Mg, Si, Zn, Mn, and Ni. They are widely used in aircraft, home appliances, construction, vehicles, machinery, electrical appliances, and other household and industrial fields.

[0003] This aluminum alloy is made by melting and casting raw aluminum ingots and alloying elements to form billets, which are then subjected to homogenization heat treatment as needed and then extruded into a specified shape.

[0004] Aluminum is classified by alloy type: No. 1000 is pure aluminum containing more than 99.00wt% aluminum, No. 2000 is Al-Cu alloy, No. 3000 is Al-Mn alloy, No. 4000 is Al-Si alloy, No. 5000 is Al-Mg alloy, No. 6000 is Al-Mg-Si alloy, and No. 7000 is Al-Zn alloy.

[0005] Among them, the 7000 aluminum alloy uses Cr in the 7075 alloy as Zr replacement to form the 7050 alloy, which has higher strength and good resistance to stress corrosion cracking, and its hardenability is also improved. There are also 7150 alloys that improve the strength of the 7050 alloy by about 10%, 7475 alloys that improve the fracture toughness and fatigue properties by limiting the impurities in the 7075 alloy, and 7010 alloys that improve the fracture toughness by slightly reducing the amount of Cu in the 7050 alloy. As casting materials, the tensile strength of the quenched Al-1.3%Cu-5%Si-0.5%Mg alloy or Al-7%Si-0.3%Mg alloy is 25 to 35kg / m 2 , strength of 20 to 25 kg / m 2 , elongation is 1 to 10%, while Al-5% Zn-2% Mg alloy obtains a tensile strength of 45 kg / m by aging treatment 2 materials.

[0006] Meanwhile, Korean Patent Publication No. 10-2012-0135546 discloses a method for manufacturing an aluminum alloy with scandium addition, characterized in that the method includes a dissolution treatment step for controlling the recrystallization fraction and the amount of vacancy cluster formation and increasing the elongation after the casting and homogenization steps of the Al-Zn-Mg-Cu-Zr-Ti-Sc alloy, and a natural aging step for depositing it into the GP zone at room temperature to increase the strength.

[0007] In addition, Korean registered patent No. 10-0909699 discloses an aluminum alloy containing scandium, characterized in that, based on the total weight percentage of the aluminum alloy, the silicon content is greater than 0 and less than 0.1, the iron content is greater than 0 and less than 0.1, the copper content is greater than 1.5 and less than 2.5, the magnesium content is greater than 1.8 and less than 2.2, the zinc content is greater than 7.6 and less than 8.4, the zirconium content is greater than 0.11 and less than 0.15, the titanium content is greater than 0.02 and less than 0.08, the scandium content is greater than 0.08 and less than 0.12, and the beryllium content is greater than 0.05 and less than 0.1. Summary of the Invention

[0008] Technical problems to be solved

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an aluminum alloy having excellent strength and elongation and a method for producing the same.

[0010] Technical Solution

[0011] In order to achieve the above object, a method for manufacturing an aluminum-scandium alloy according to an embodiment of the present invention is characterized in that it includes the following steps: 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 to 760° C.; and finally obtaining a master alloy ingot of Cu 2.0 to 4.5 wt %, Mg 2.0 to 4.5 wt %, Mn 0.001 to 0.05 wt %, Zn 5.5 to 10.5 wt %, Ti 0.002 to 0.05 wt %, Sc 0.006 to 0.006 wt % in a melting furnace at 730 to 760° C. 0.03wt%, inevitable impurities and the remaining weight portion become Al and the ingot is added and stirred; the internal structure of the stirred alloy is homogenized at 400 to 450° C., and the alloy is ripened in a nitrogen atmosphere furnace for more than 24 hours; the ripened alloy is extruded into an ingot, an extruded part or a rolled part; the extruded alloy is gradually heated to 480° C.; and the heated alloy is rapidly cooled to a temperature between 27° C. and -198° C., wherein the impurities contain less than 0.1wt% Fe and less than 0.12ml / 100g hydrogen.

[0012] Beneficial effects

[0013] The alloy produced according to the present invention has excellent tensile strength and yield strength as well as excellent elongation, and is therefore expected to be used in various industrial fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a graph showing the hydrogen content in an alloy produced according to one embodiment of the present invention.

[0015] Figure 2is a graph showing the thickness of the chill layer of an alloy manufactured according to one embodiment of the present invention.

[0016] Figure 3 is a graph showing the grain size of alloys produced according to examples of the present invention. DETAILED DESCRIPTION

[0017] The method for manufacturing an aluminum-scandium alloy according to one embodiment of the present invention comprises the steps of manufacturing an ingot of an Al-Cu, Al-Mg, Al-Mn, Al-Zn, Al-Ti and Al-Sc master alloy in a nitrogen atmosphere furnace at 700 to 760° C.; and finally preparing a master alloy of Cu 2.0 to 4.5 wt %, Mg 2.0 to 4.5 wt %, Mn 0.001 to 0.05 wt %, Zn 5.5 to 10.5 wt %, Ti 0.002 to 0.05 wt %, Sc 0.006 to 0.03 wt % in a furnace at 730 to 760° C. The invention relates to a method for producing an alloy comprising the steps of: adding 100 wt% of an ingot and stirring the ingot so that inevitable impurities and the remainder by weight are Al; homogenizing the internal structure of the stirred alloy at 400 to 450° C.; aging the alloy in a nitrogen atmosphere furnace for more than 24 hours; extruding the aging alloy into an ingot, an extruded part or a rolled part; gradually heating the rolled alloy to 480° C.; and rapidly cooling the heated alloy to a temperature between 27° C. and -198° C. The alloy thus produced contains less than 0.1 wt% of Fe and less than 0.12 ml / 100 g of hydrogen as an impurity.

[0018] The present invention can be realized through the following description. The following description should be understood as describing preferred embodiments of the present invention, and the present invention is not necessarily limited thereto. In addition, the accompanying drawings are for the purpose of aiding understanding, and the present invention is not limited thereto, and the details of each configuration can be appropriately understood by the specific purpose of the related description described later.

[0019] In this specification, when any component is “included”, it means that other components may be further included unless otherwise specified.

[0020] Furthermore, in this specification, the term “located on the upper side” or “located on the lower side” may be understood to indicate a relative positional relationship in a contact state and a non-contact state with a specific object.

[0021] "Corrosion" can refer to the destructive phenomenon of metals directly subjected to electrochemical or chemical reactions in a given environment.

[0022] "Casting" refers to the process of melting metal into liquid in a furnace, then pouring it into a mold and cooling it to produce metal products of a certain shape. It can be divided into die casting (using consumable materials such as sand as a casting mold), mold casting, die casting, special casting, etc.

[0023] "Master alloy" refers to a primary alloy in which the alloy element content is increased to about 10% to 20% in advance in order to suppress the uneven distribution of alloy elements caused by segregation and minimize the loss of high-priced alloy elements when the alloy element content is trace (usually less than 1%).

[0024] Formula of aluminum alloy raw materials

[0025] In the present invention, the aluminum alloy raw material is mainly composed of aluminum, but may contain copper, magnesium, manganese, zinc, titanium, scandium and other inevitable impurities. At this time, the raw material can be used in the form of powder, granules or ingots.

[0026] In the process of manufacturing the aluminum-scandium alloy, separate master alloys are prepared for each element of the alloy and then mixed to produce the final alloy. After the master alloys of different elements are prepared, the alloy is prepared to ensure the uniformity of the trace elements in the final product and prevent impurities generated by reactions between the elements.

[0027] Scandium (Sc) in aluminum alloy raw materials refines the alloy's grain size, thereby increasing its resistance to high-temperature cracking and impacting the alloy's strength and elongation. Excessive addition of Scandium (Sc) can lead to segregation of undissolved Sc, potentially degrading performance. With this in mind, in the present invention, the amount of Scandium (Sc) in the alloy raw materials is controlled within a range of 0.001 to 1 wt%, specifically, approximately 0.003 to 0.5 wt%, and more specifically, approximately 0.006 to 0.1 wt%.

[0028] Hydrogen is generated during the casting process and incorporated into the alloy, creating pores that expand into solidification shrinkage defects and reduce fatigue strength. Therefore, research into reducing the hydrogen content in alloys continues. In the present invention, the hydrogen content in the alloy raw material is controlled to below 0.12 ml / 100 g, more specifically, within the range of 0.09 ml / 100 g.

[0029] Iron (Fe) is an impurity in the alloy manufacturing process. As the iron content increases, the tensile strength of the alloy decreases, so it is crucial to minimize the iron content in the alloy. The alloy manufactured according to the manufacturing method of the present invention contains less than 0.1wt% Fe.

[0030] Method for manufacturing aluminum-scandium alloy

[0031] The method for manufacturing an aluminum-scandium alloy according to one embodiment of the present invention may include a step of manufacturing a master alloy ingot, a stirring step, a aging step, an extrusion and rolling step, a heating step, and a cooling step.

[0032] The step of making a master alloy ingot is a step of making Al-Cu, Al-Mg, Al-Mn, Al-Zn, Al-Ti and Al-Sc master alloys. This is a step of making a separate master alloy for each element to improve the uniformity of the metal in the aluminum alloy.

[0033] A nitrogen atmosphere furnace is a furnace filled with nitrogen to prevent the melt from being exposed to the atmosphere.

[0034] More specifically, the aluminum-copper master alloy ingot is produced by adding aluminum with a purity of 98-99.5% to a nitrogen atmosphere melting furnace, maintaining the temperature at 700-750°C, removing dross, and adding copper. The aluminum and copper are then mixed in the nitrogen atmosphere melting furnace for 10 to 30 hours. The aluminum-copper master alloy ingot can be produced with a copper content of 5 to 15% by weight.

[0035] The steps for producing an aluminum-magnesium master alloy ingot are to charge aluminum with a purity of 98-99.5% into a nitrogen atmosphere melting furnace, maintain the temperature at 700-750°C, remove the scum, and add magnesium. The aluminum and magnesium are mixed in the nitrogen atmosphere melting furnace for 10 to 30 hours. The aluminum-magnesium master alloy ingot can be produced with a magnesium content of 5 to 15% by weight.

[0036] The steps for producing an aluminum-manganese master alloy ingot are to charge aluminum with a purity of 98-99.5% into a nitrogen atmosphere melting furnace, maintain the temperature at 700-770°C, remove the scum, and then add manganese. The aluminum and manganese are mixed in the nitrogen atmosphere melting furnace for 10 to 30 hours. The aluminum-manganese master alloy ingot can be produced with a manganese content of 5 to 15% by weight.

[0037] The aluminum-zinc master alloy ingot is produced by adding aluminum with a purity of 98-99.5% to a nitrogen atmosphere melting furnace and maintaining the temperature at 700-750°C. The dross is then removed and zinc is added. The aluminum and zinc are mixed in the nitrogen atmosphere melting furnace for a period of 10 to 30 hours. The aluminum-zinc master alloy ingot can be produced with a zinc content of 15 to 25% by weight.

[0038] The aluminum-titanium master alloy ingot is produced by adding aluminum with a purity of 98-99.5% to a nitrogen atmosphere melting furnace and maintaining the temperature at 700-750°C. The dross is then removed and titanium is added. The aluminum and titanium are mixed in the nitrogen atmosphere melting furnace for a period of more than 10 hours and less than 30 hours. The aluminum-titanium master alloy ingot can be produced with a titanium content of 1 to 10% by weight.

[0039] The aluminum-scandium master alloy ingot is produced by adding aluminum with a purity of 98-99.5% to a nitrogen atmosphere melting furnace and maintaining the temperature at 700-770°C. The dross is then removed and scandium is added. The aluminum and scandium are mixed in the nitrogen atmosphere melting furnace for at least 30 hours but less than 50 hours. The aluminum-scandium master alloy ingot can be produced with a scandium content of 1 to 5% by weight.

[0040] The master alloy manufacturing step is carried out in a sealed nitrogen container to reduce the hydrogen solubility in the alloy, and is accompanied by a process of maintaining the temperature at 730 to 760°C for 10 to 30 hours after degassing and nitrogen sealing to eliminate segregation of the secondary alloy.

[0041] The stirring step involves adding the master alloy after the master alloy ingot is made, mixing the master alloy to achieve the desired element ratios in the aluminum alloy, and then stirring. The stirring process involves adding aluminum with a purity of 85 to 99.5% to a furnace at 730 to 760°C. Then, copper, magnesium, zinc, manganese, and scandium master alloys are added at regular intervals to determine the final alloy composition: Cu 2.0 to 4.5 wt%, Mg 2.0 to 4.5 wt%, Mn 0.001 to 0.05 wt%, Zn 5.5 to 10.5 wt%, Ti 0.002 to 0.05 wt%, Sc 0.006 to 0.03 wt%, with inevitable impurities and the remainder being Al. As required, the final composition of the alloy is Cu 2.0 to 2.5 wt%, Mg 2.0 to 2.5 wt%, Mn 0.001 to 0.05 wt%, Zn 7 to 9 wt%, Ti 0.002 to 0.05 wt%, and Sc 0.006 to 0.03 wt%.

[0042] Furthermore, the stirring step may be performed until the alloy has a hydrogen content of less than 0.12 ml / 100 g. If the alloy has a hydrogen content exceeding 0.12 ml / 100 g during the stirring process, a hydrogen removal step may be included. If desired, the alloy may be stirred until the alloy has a hydrogen content of less than 0.09 ml / 100 g.

[0043] In addition, the impurities may contain less than 0.1 wt% iron. When the iron content increases, it will affect the mechanical properties of the alloy. Therefore, when making the master alloy, the content of iron impurities can be limited to less than 0.1 wt%.

[0044] The aging step is a step of aging the stirred alloy at a certain temperature for a certain time to homogenize the interior of the stirred alloy. According to the present invention, the stirred alloy can be aging in a nitrogen atmosphere furnace at 400 to 450° C. for more than 24 hours.

[0045] The extrusion step is a step of extruding the slaked alloy into an ingot, an extruded piece or a rolled piece. Extrusion, rolling and extrusion techniques are well known in the art, so a detailed description thereof is omitted.

[0046] The heating step involves gradually heating the rolled alloy to 480°C. This heat treatment method restructures the binary microstructure. If necessary, the heating step can be continued to steps 6 through 10. The room-temperature alloy can be heated to 480°C sequentially through 50°C, 80°C, 100°C, 150°C, 200°C, 300°C, and 400°C, holding at each temperature for 1 to 24 hours.

[0047] The rapid cooling step refers to the step of rapidly cooling the heated alloy to 27°C to -198°C. The rapid cooling step is a process of rapidly cooling the casting that has undergone the heating step at a cooling rate of more than 100°C / second to enhance toughness. The rapid cooling method is to use liquid nitrogen or water as a commonly used method. Usually, aluminum and aluminum-containing alloys are usually cooled without rapid cooling, but in the case of the aluminum-scandium alloy of the present invention, due to the rapid migration rate of scandium in the grains and grain boundaries, segregation may occur rapidly, so a rapid cooling process is required to suppress segregation. After the alloy is rapidly cooled, scandium and magnesium elements are evenly distributed in the grains instead of segregating in the grains, thereby minimizing the occurrence of intergranular brittle fractures and microcracks, thereby improving toughness and tensile strength. The boundary brittle failure phenomenon here refers to the low-temperature brittle failure caused by the segregation of impurities at the boundary.

[0048] According to one embodiment, the (Mn+Ti+Fe) / Sc value of the alloy produced according to the present invention can be less than or equal to 5.25. When the (Mn+Ti+Fe) / Sc value exceeds 5.25, the tensile strength and yield strength will drop sharply. For the alloy produced according to the present invention, 700N / mm 2 The excellent tensile strength is shown in Table 2. Among the alloys manufactured, samples A and B are alloys with (Mn+Ti+Fe) / Sc values ​​less than 5.25, and exhibit 700 N / mm 2 Excellent tensile strength above 650N / mm 2 Excellent yield strength above .

[0049] Example

[0050] The tensile strength, yield strength, and elongation of the alloy prepared in this example were measured using ASTM E8 / E8M-21.

[0051]

Table 1

[0052] Element content

[0053] Cu Mg Mn Zn Ti Sc Fe Sample A 2.002 2.056 0.001 7.499 0.005 0.019 0.072 Sample B 2.35 2.23 0.001 9.09 0.0052 0.013 0.062 Sample C 1.01 1.72 0.0027 6.46 0.0048 0.01 0.17

[0054]

Table 2

[0055] Tensile strength, yield strength and elongation

[0056]

[0057] According to one embodiment, the average grain size of the alloy after the rapid cooling process may be greater than 100 μm and less than 200 μm. With the rapid cooling, fine grains are generated in the alloy, which has a positive effect on the tensile strength.

[0058] Furthermore, the chill layer produced in rapidly cooled alloys can be less than 1 mm. The thickness of the chill layer is affected by the cooling rate.

[0059] According to one embodiment of the present invention, the surface of the alloy after the rapid cooling process may have a dendritic microstructure. In addition, the tensile strength of the alloy manufactured according to the embodiment of the present invention is 650N / mm 2 Above, elongation 10% or more, yield strength 600N / mm 2 above.

[0060] According to another embodiment of the present invention, the aluminum-scandium alloy includes 2.0 to 4.5 wt% Cu, 2.0 to 4.5 wt% Mg, 0.001 to 0.05 wt% Mn, 5.5 to 10.5 wt% Zn, 0.002 to 0.05 wt% Ti, and 0.006 to 0.03 wt% Sc. Unavoidable impurities and the remaining weight may be Al. As needed, the final composition of the alloy is 2.0 to 2.5 wt% Cu, 2.0 to 2.5 wt% Mg, 0.001 to 0.05 wt% Mn, 7 to 9 wt% Zn, 0.002 to 0.05 wt% Ti, and 0.006 to 0.03 wt% Sc.

[0061] In addition, the impurities of the alloy according to the present invention may include less than 0.1 wt% Fe and less than 0.12 ml / 100 g hydrogen. In addition, the (Mn+Ti+Fe) / Sc value of the alloy according to the present invention may not exceed 5.25, and may have excellent tensile strength and yield strength. The tensile strength of the alloy produced according to the present invention is 650 N / mm 2 Above, the elongation can reach more than 10%, and the alloy yield strength can reach 600N / mm 2 As required, alloys that satisfy the above expression can exhibit 700N / mm 2 Excellent tensile strength and 650N / mm 2 Excellent yield strength above .

[0062] Furthermore, the average grain size of the alloy according to the present invention may be greater than 100 μm and less than 200 μm.

[0063] The aluminum-scandium alloy manufactured according to the present invention has excellent tensile strength, yield strength and elongation, and is expected to be used in various industrial fields in the future.

[0064] The present invention has been described in detail above, but the present invention is not limited to the contents described above. Various modifications and variations are possible without departing from the technical concept of the present invention. Therefore, the contents described above are intended to illustrate rather than limit the technical concept of the present invention. Therefore, the scope of protection of the present invention should be interpreted in accordance with the claims, and all technical concepts within the scope of their equivalents should be interpreted as included within the scope of the present invention.

Claims

1. A method for producing an aluminum-scandium alloy, characterized in that: include: The step 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 to 760°C; a step of adding and stirring the ingot in a furnace at 730 to 760° C. to obtain a final composition of Cu 2.0 to 4.5 wt %, Mg 2.0 to 4.5 wt %, Mn 0.001 to 0.05 wt %, Zn 5.5 to 10.5 wt %, Ti 0.002 to 0.05 wt %, Sc 0.006 to 0.03 wt %, inevitable impurities and the remaining weight portion becoming Al; a aging step of homogenizing the internal structure of the stirred alloy at 400 to 450° C. and aging the alloy in a nitrogen atmosphere furnace for more than 24 hours; The step of extruding the slaked alloy into an ingot, an extrusion or a rolled product; The step of gradually heating the extruded alloy to 480° C. The step of rapidly cooling the heated alloy to a temperature between 27°C and -198°C, The impurities contain less than 0.1 wt% of Fe and less than 0.12 ml / 100 g of hydrogen.

2. The method for producing an aluminum-scandium alloy according to claim 1, wherein: The alloy is manufactured so that the (Mn+Ti+Fe) / Sc value does not exceed 5.

25.

3. The method for producing an aluminum-scandium alloy according to claim 1, wherein: The average grain size of the rapidly cooled alloy is greater than 100 μm and less than 200 μm.

4. The method for producing an aluminum-scandium alloy according to claim 3, wherein: The chill layer formed in the rapidly cooled alloy is less than 1 mm.

5. The method for producing an aluminum-scandium alloy according to claim 4, wherein: The rapidly cooled alloy surface has a dendritic microstructure.

6. The method for producing an aluminum-scandium alloy according to claim 5, wherein: The tensile strength of the alloy produced is 650N / mm 2 above.

7. The method for producing an aluminum-scandium alloy according to claim 6, wherein: The produced alloy has an elongation of 10% or more.

8. The method for producing an aluminum-scandium alloy according to claim 7, wherein: The yield strength of the alloy produced is 600N / mm 2 above.

9. An aluminum-scandium alloy, as an aluminum-scandium alloy, characterized in that: Cu2.0 to 4.5wt%, Mg2.0 to 4.5wt%, Mn0.001 to 0.05wt%, Zn5.5 to 10.5wt%, Ti0.002 to 0.05wt%, Sc0.006 to 0.03wt% and unavoidable impurities, and the balance by weight includes Al, Impurities in the alloy, Containing less than 0.1wt% Fe and less than 0.12ml / 100g hydrogen, The alloy, The (Mn+Ti+Fe) / Sc value does not exceed 5.

25.

10. The aluminum-scandium alloy according to claim 9, characterized in that The tensile strength of the alloy is 650N / mm 2 above, The elongation of the alloy is, 10% or more, The yield strength of the alloy is, 600N / mm 2 above.

11. The aluminum-scandium alloy according to claim 10, characterized in that The average grain size of the alloy is greater than 100 μm and less than 200 μm.

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