Aluminum alloy with high Fe content and high comprehensive performance and preparation method thereof

Abstract

The invention discloses a high-Fe-content and high-comprehensive-performance aluminum alloy and a preparation method thereof.The specific method comprises the following steps that firstly, reasonable smelting and refining processes are adopted, three different modifiers are added to conduct Fe phase modification treatment on waste aluminum materials, and the existence form of the Fe element is controlled; and carrying out homogenization heat treatment and deformation heat treatment to obtain the high-temperature-resistant alloy. Through alloy component design and machining process optimization, the characteristics of morphology, distribution and the like of the Fe-rich phase are changed, phase change of the Fe-containing phase is achieved, the interface behavior of the Fe-containing phase is regulated and controlled, then accurate control over the microstructure of the high-Fe-content aluminum alloy is achieved, and high comprehensive performance is obtained. The high-Fe-content 6XXX series aluminum alloy prepared through the method has excellent mechanical performance and corrosion resistance, the application requirement of the high-quality 6XXX series aluminum alloy can be met, and a new way is provided for high-value utilization of secondary aluminum.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal material processing, specifically relating to a high-Fe-content aluminum alloy with high comprehensive performance and its preparation method. Background Technology

[0002] Aluminum alloys are widely used in transportation, construction, aerospace, and other fields due to their advantages such as low density, high specific strength, and easy recyclability. With the continuous growth in aluminum product production, the recycling of scrap aluminum alloys has become an important way to alleviate resource shortages, reduce production costs, and achieve green manufacturing. The efficient recycling of aluminum alloy scrap not only saves a significant amount of aluminum resources and reduces production costs, but also helps reduce environmental pollution and carbon emissions, resulting in significant economic benefits and environmental significance.

[0003] However, in the actual recycling process of aluminum scrap, the complex sources, difficult pretreatment, and difficulty in effectively controlling the content of impurity elements often lead to the downgrading of recycled aluminum alloys. Iron (Fe) is one of the most common impurities in recycled aluminum. Excessive Fe content can cause the formation of coarse iron-rich phases within the alloy, severely reducing the strength, toughness, fracture toughness, and corrosion resistance of the aluminum alloy, thus limiting its application range. Currently, methods to reduce the Fe content in recycled aluminum mainly include dilution, centrifugal separation, ceramic filtration, electromagnetic separation, and sedimentation. However, these methods are complex, costly, and cannot completely remove Fe, so the performance of recycled aluminum alloys still cannot meet industrial demands. Given the difficulty in completely removing Fe and the high cost, simply relying on reducing Fe content to improve aluminum alloy performance is no longer suitable for the development needs of the recycled aluminum industry. Therefore, from the perspective of optimizing the performance of high-Fe content aluminum alloys, developing a high-Fe content aluminum alloy with excellent comprehensive performance by rationally designing alloy composition and smelting processes, and controlling the existence form and distribution of Fe in the alloy, has become an important technical path to solve the problem of efficient utilization of recycled aluminum.

[0004] Studies have shown that the acicular β-Fe phase is the most harmful Fe-rich phase in aluminum alloys. It hinders feeding and forms casting porosity during casting, and easily causes stress concentration, reducing the mechanical properties of the alloy. Therefore, promoting the modification and refinement of the β-Fe phase is an effective method to enhance the comprehensive performance of high-Fe content aluminum alloys. CN119265461A proposes a high-strength, high-toughness recycled Al-Mn-Mg aluminum alloy, its preparation method, and its applications. By adding alloying elements such as La, Ce, and Sr to the melt, the type, morphology, and distribution of the iron-rich phase in the alloy are improved, thereby weakening the harmful effects of the Fe-rich phase. However, this method only achieves the preservation and utilization of scrap aluminum alloys. For the upgrading and utilization of recycled aluminum, in addition to improving the type, size, and distribution of the Fe-rich phase, it is also necessary to further regulate the deformation structure and aging precipitation behavior of the aluminum alloy to comprehensively improve its overall performance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-Fe-content, high-performance aluminum alloy and its preparation method. The method mainly involves adding different types of modifiers to promote the modification and refinement of the Fe-containing phase. At the same time, the added modifier elements form a large number of submicron dispersed phases in the matrix, improving the deformed structure and obtaining a large number of small-angle grain boundaries and substructures. This synergistically enhances the strength and toughness of the alloy, while also improving its corrosion resistance.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing a high-Fe content aluminum alloy with high comprehensive performance includes the following steps:

[0008] Step 1) Smelting and casting: First, melt the Fe-containing scrap aluminum; then, introduce inert gas for the first refining; adjust the composition of the main alloying elements; then, add the first type of modifier and the second type of modifier to the aluminum liquid in sequence and stir thoroughly; introduce inert gas for the second refining; then add the third type of modifier and let it stand; cast to obtain alloy ingots;

[0009] Step 2) Homogenization heat treatment: The alloy ingot obtained in Step 1) is subjected to homogenization heat treatment using a single-stage or double-stage homogenization heat treatment regime.

[0010] Step 3) Deformation heat treatment: The alloy ingot after homogenization in step 2) is subjected to extrusion hot deformation, followed by water cooling and artificial aging to obtain the final product.

[0011] Preferably, the control range of the main alloying element composition in step 1) is: 0.6~1.2 wt.% Mg, 0.6~1.4 wt.% Si, 0.01~0.7 wt.% Cu, and 0.2~1.0 wt.% Fe.

[0012] Preferably, in step 1), the first type of modifier is one or more of Al-Mn, Al-Cr, Al-Mo, Al-Co, and Al-Ni master alloys; the second type of modifier is one or more of Al-Nd, Al-Nb, Al-Y, Al-Er, Al-La, and Al-Ce master alloys; and the third type of modifier is one or more of Al-Ti-B and Al-Zr master alloys.

[0013] Preferably, when the first type of modifier is added, the amount of Mn added in the Al-Mn master alloy is 50% to 100% of the Fe content in the alloy ingot; the amount of Cr added in the Al-Cr master alloy is 20% to 50% of the Fe content in the alloy ingot; the amount of Mo added in the Al-Mo master alloy is 20% to 50% of the Fe content in the alloy ingot; the amount of Co added in the Al-Co master alloy is 20% to 50% of the Fe content in the alloy ingot; and the amount of Ni added in the Al-Ni master alloy is 20% to 50% of the Fe content in the alloy ingot.

[0014] Preferably, when the second type of modifier is added, the amount of Nd added in the Al-Nd master alloy is 10% to 40% of the Fe content in the alloy ingot; the amount of Nb added in the Al-Nb master alloy is 10% to 40% of the Fe content in the alloy ingot; the amount of Y added in the Al-Y master alloy is 20% to 50% of the Fe content in the alloy ingot; the amount of Er added in the Al-Er master alloy is 20% to 80% of the Fe content in the alloy ingot; the amount of La added in the Al-La master alloy is 10% to 50% of the Fe content in the alloy ingot; and the amount of Ce added in the Al-Ce master alloy is 10% to 50% of the Fe content in the alloy ingot.

[0015] Preferably, when a third type of modifier is added, the amount of Ti added in the Al-Ti master alloy is 10% to 20% of the Fe content in the alloy ingot; and the amount of Zr added in the Al-Zr master alloy is 20% to 50% of the Fe content in the alloy ingot.

[0016] Preferably, the single-stage homogenization heat treatment process in step 2) is as follows: the temperature is increased from room temperature to 530-560°C at a heating rate of 1-3°C / min, and held at this temperature for 14-18 hours, followed by air cooling or water cooling.

[0017] The two-stage homogenization heat treatment process is as follows: the ingot is held at 200~350℃ for 6~10 h, then heated to 530~560℃ at a heating rate of 2~5℃ / min, and held at this temperature for 8~12 h, followed by air cooling or water cooling.

[0018] Preferably, the parameters for the extrusion hot deformation in step 3) are as follows: deformation temperature is 500~540℃, extrusion ratio is controlled at 10:1~30:1, and extrusion speed is 2~10 mm / min.

[0019] Preferably, the artificial aging process in step 3) is as follows: heat preservation at 160~200℃ for 5~10 hours.

[0020] The aluminum alloy prepared by the above method is a 6XXX series aluminum alloy.

[0021] The beneficial effects of this invention are as follows:

[0022] (1) Fe-rich phase transformation and refinement: In the preparation process of the aluminum alloy of the present invention, the addition of Mn, Cr, Mo, Co and Ni elements alone or in combination can promote the transformation of acicular β-Fe phase into skeletal α-Fe phase. The addition of Nd, Nb, Y, Er, La and Ce elements alone or in combination can significantly increase the nucleation sites of the Fe-rich phase, and at the same time, they agglomerate on both sides of the Fe-rich phase and inhibit its growth, thereby refining the α-Fe phase. The addition of Zr and Ti alone or in combination can significantly refine the grains.

[0023] (2) Improve deformation structure and enhance mechanical properties: During the homogenization heat treatment process, the addition of Mn, Cr and Mo elements alone or in combination will form a large number of submicron-sized α-Al(FeM)Si (M = Mn, Cr, Mo) dispersed phases; the addition of Ni, Nb, Zr, Er, Y, Ti and other elements alone or in combination will form a large number of nano-sized Al3M (M = Ni, Nb, Zr, Er, Y, Ti) dispersed phases. These dispersed phases will pin dislocations and grain boundaries during the subsequent hot deformation process, which can significantly inhibit recrystallization, obtain a large number of small-angle grain boundaries and substructures, and synergistically improve the strength and toughness of the alloy.

[0024] (3) Improved corrosion resistance: In the preparation process of the aluminum alloy of the present invention, the addition of Cr, Zr, La and Ce elements alone or in combination will form oxides such as Cr2O3, ZrO2, La2O3 and Ce2O3 on the alloy surface, which can enhance the density and stability of the surface oxide film, thereby improving the corrosion resistance of the alloy. Attached Figure Description

[0025] Figure 1 TEM image and energy dispersive spectral surface scan of Al(FeMn)Si dispersed phase in aluminum alloy prepared in Example 1;

[0026] Figure 2 This is a diagram of the as-cast microstructure of the aluminum alloy obtained in Example 1;

[0027] Figure 3 The image shows the as-cast microstructure of the aluminum alloy obtained in Comparative Example 1.

[0028] Figure 4 This is a diagram of the as-cast microstructure of the aluminum alloy obtained in Comparative Example 2. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art, and the experimental methods without specific conditions are all conventional methods in the art.

[0031] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0032] A method for preparing a high-Fe content aluminum alloy with high comprehensive performance, the specific steps of which are as follows:

[0033] (1) Smelting and casting

[0034] Waste aluminum is fed into the smelting furnace and melted at a temperature between 720 and 780°C.

[0035] After the scrap aluminum is melted, the aluminum liquid is first refined by introducing inert gas and stirring continuously for 10 to 30 minutes, followed by slag removal.

[0036] Small samples were taken for composition analysis, and the main alloying elements Al, Mg, Si, and Cu were adjusted to meet the corresponding range requirements. The composition ranges of each element by mass percentage were: 0.6~1.2 wt.% Mg, 0.6~1.4 wt.% Si, 0.01~0.7 wt.% Cu, and 0.2~1.0 wt.% Fe.

[0037] Add the first type of modifier to the molten aluminum and stir continuously;

[0038] The first type of modifier is one or more of Al-Mn, Al-Cr, Al-Mo, Al-Co, and Al-Ni master alloys, and its function is to promote the transformation of the acicular β-Fe phase to the skeletal α-Fe phase. The mass ratios of Mn / Fe are (0.5~1.0):1; Cr / Fe are (0.2~0.5):1; Mo / Fe are (0.2~0.5):1; Co / Fe are (0.2~0.5):1; and Ni / Fe are (0.2~0.5):1.

[0039] Add a second type of modifier to the molten aluminum and stir continuously;

[0040] The second type of modifier is one or more of Al-Nd, Al-Nb, Al-Y, Al-Er, Al-La, and Al-Ce master alloys. Its function is to refine the acicular β-Fe phase and skeletal α-Fe phase in the alloy. The mass ratio of Nd / Fe is (0.1~0.4):1; the mass ratio of Nb / Fe is (0.1~0.4):1; the mass ratio of Y / Fe is (0.2~0.5):1; the mass ratio of Er / Fe is (0.2~0.8):1; the mass ratio of La / Fe is (0.1~0.5):1; and the mass ratio of Ce / Fe is (0.1~0.5):1.

[0041] The molten aluminum is then refined a second time by introducing inert gas and stirring continuously for 10-30 minutes, followed by slag removal.

[0042] Add the third type of modifier to the molten aluminum and stir continuously, then let it stand for 5 to 10 minutes;

[0043] The third type of modifier is one or more of Al-Ti and Al-Zr master alloys, which are used to refine grains. The mass ratio of Ti / Fe is (0.1~0.2):1, and the mass ratio of Zr / Fe is (0.2~0.5):1.

[0044] A semi-continuous casting process is used to obtain alloy ingots.

[0045] (2) Homogenization heat treatment

[0046] The homogenization heat treatment of alloy ingots can be carried out by a single-stage or multi-stage homogenization heat treatment system.

[0047] The single-stage homogenization heat treatment process is as follows: the temperature is increased from room temperature to 530-560℃ at a heating rate of 1-3℃ / min, and held at this temperature for 14-18 hours, followed by air cooling or water cooling.

[0048] The two-stage homogenization heat treatment process is as follows: the ingot is held at 200~350℃ for 6~10 h, then heated to 530~560℃ at a heating rate of 2~5℃ / min, and held at this temperature for 8~12 h, followed by air cooling or water cooling.

[0049] (3) Deformation heat treatment

[0050] The homogenized ingot is subjected to deformation heat treatment;

[0051] Preferably, in order to promote the crushing of the Fe-rich phase, the ingot is hot-deformed by extrusion, with a deformation temperature of 500~540℃, an extrusion ratio controlled at (10~30):1, and an extrusion speed of 2~10 mm / min.

[0052] The extruded alloy is cooled using water cooling.

[0053] Finally, the alloy is artificially aged by holding it at 160~200℃ for 5~10 hours to obtain the final product.

[0054] Example 1

[0055] A method for preparing a high-Fe content aluminum alloy with high comprehensive performance, the specific steps of which are as follows:

[0056] (1) Add 50 kg of scrap aluminum (containing Fe) to the smelting furnace, heat the furnace to 750℃ to melt it, and after the scrap aluminum melts, introduce inert gas into the aluminum liquid and stir continuously for 10~30 min to carry out a first refining, and remove the surface residue; take a small sample for composition determination, in which the Fe element mass fraction is 0.68 wt.%, add pure Al, pure Mg, pure Cu, and Al-20Si master alloy to the aluminum liquid to adjust the composition, so that the Mg, Cu, and Si element compositions are 0.8 wt.%, 0.9 wt.%, and 0.5 wt.%, respectively; add Al-10Mn master alloy to the aluminum liquid to carry out the first modification of the melt and stir continuously, and let it stand for 10 min to control the Mn content to 0.7 wt.%; then add Al-5Nb master alloy to the aluminum liquid to carry out the second modification of the aluminum liquid and stir continuously to control the Nb content to 0.1%. The aluminum liquid was then refined a second time by introducing inert gas and stirring continuously for 15 minutes. After that, Al-10Zr master alloy was added to the aluminum liquid for a third modification and stirring continuously to control the Zr content at 0.15 wt.%. After standing for 5 minutes, a semi-continuous casting process was used to obtain an alloy ingot with a diameter of 183 mm.

[0057] (2) The alloy ingot was subjected to homogenization heat treatment using a single-stage homogenization process. The ingot was heated from room temperature to 555°C at a heating rate of 2°C / min and held at that temperature for 14 h before being air-cooled.

[0058] (3) The ingot is deformed by hot extrusion at a temperature of 530°C, an extrusion ratio of 25:1, and an extrusion speed of 4 mm / min. The extruded alloy is cooled by water cooling and artificially aged at 175°C for 6 h.

[0059] like Figure 1 As shown, the aluminum alloy matrix prepared in this embodiment contains a large number of submicron-sized dispersed phases, which can pin dislocations and grain boundaries, significantly inhibit the recrystallization behavior of the sample during subsequent hot deformation, improve the microstructure of the alloy, and enhance the strength and toughness of the alloy.

[0060] Example 2

[0061] A method for preparing a high-Fe content aluminum alloy with high comprehensive performance, the specific steps of which are as follows:

[0062] (1) Add 50 kg of scrap aluminum (containing Fe) to the smelting furnace, heat the furnace to 750℃ to melt it, and after the scrap aluminum melts, introduce inert gas into the aluminum liquid and stir continuously for 10~30 min to perform a first refining, and remove the surface residue; take a small sample for composition determination, in which the Fe element mass fraction is 0.79 wt.%, add pure Al, pure Mg, pure Cu, and Al-20Si master alloy to the aluminum liquid to adjust the composition, so that the Mg, Cu, and Si element compositions are 0.8 wt.%, 0.9 wt.%, and 0.5 wt.%, respectively; add Al-10Mn and Al-10Cr master alloy to the aluminum liquid to perform the first modification of the melt and stir continuously, and let it stand for 10 min, and control the Mn and Cr contents to 0.4 wt.% and 0.2 wt.%, respectively. Subsequently, Al-10La and Al-10Ce master alloys were added to the molten aluminum for a second modification and continuous stirring, with the La and Ce contents controlled at 0.2 wt.% and 0.1 wt.%, respectively. The molten aluminum was then refined a second time by introducing inert gas and stirring continuously for 15 min. After that, Al-5Ti-B master alloys were added to the molten aluminum for a third modification and continuous stirring, with the Ti content controlled at 0.08 wt.%. After standing for 5 min, a semi-continuous casting process was used to obtain an alloy ingot with a diameter of 183 mm.

[0063] (2) The alloy ingot was subjected to homogenization heat treatment using a single-stage homogenization process. The ingot was heated from room temperature to 555°C at a heating rate of 2°C / min and held at that temperature for 14 h before being air-cooled.

[0064] (3) The ingot is deformed by hot extrusion at a temperature of 530°C, an extrusion ratio of 25:1, and an extrusion speed of 4 mm / min. The extruded alloy is cooled by water cooling and artificially aged at 175°C for 6 h.

[0065] Example 3

[0066] A method for preparing a high-Fe content aluminum alloy with high comprehensive performance, the specific steps of which are as follows:

[0067] (1) Add 50 kg of scrap aluminum (containing Fe) to the smelting furnace, heat the furnace to 750℃ to melt it, and after the scrap aluminum melts, introduce inert gas into the aluminum liquid and stir continuously for 10~30 min to carry out the first refining, and remove the surface residue; take a small sample for composition determination, in which the Fe element mass fraction is 0.68 wt.%, add pure Al, pure Mg, pure Cu, and Al-20Si master alloy to the aluminum liquid to adjust the composition, so that the Mg, Cu, and Si element compositions are 0.8 wt.%, 0.9 wt.%, and 0.5 wt.%, respectively; add Al-5Co master alloy to the aluminum liquid to carry out the first modification of the melt and stir continuously, and let it stand for 10 min to control the Co content to 0.2 wt.%; then add Al-10Er master alloy to the aluminum liquid to carry out the second modification of the aluminum liquid and stir continuously to control the Er content to 0.15 wt.%; then carry out the second refining of the aluminum liquid, introduce inert gas and stir continuously for 15 min. min; then Al-10Zr master alloy was added to the aluminum melt for a third modification and stirring was continued to control the Zr content at 0.4 wt.%; after standing for 5 min, a semi-continuous casting process was used to obtain an alloy ingot with a diameter of 183 mm.

[0068] (2) The alloy ingot was subjected to homogenization heat treatment using a single-stage homogenization process. The ingot was heated from room temperature to 555°C at a heating rate of 2°C / min and held at that temperature for 14 h before being air-cooled.

[0069] (3) The ingot is deformed by hot extrusion at a temperature of 530°C, an extrusion ratio of 25:1, and an extrusion speed of 4 mm / min. The extruded alloy is cooled by water cooling and artificially aged at 175°C for 6 h.

[0070] Example 4

[0071] A method for preparing a high-Fe content aluminum alloy with high comprehensive performance, the specific steps of which are as follows:

[0072] (1) Add 50 kg of scrap aluminum (containing Fe) to the smelting furnace, heat the furnace to 750℃ to melt it, and after the scrap aluminum melts, introduce inert gas into the aluminum liquid and stir continuously for 10~30 min to carry out the first refining, and remove the surface residue; take a small sample for composition determination, in which the Fe element mass fraction is 0.68 wt.%, add pure Al, pure Mg, pure Cu, and Al-20Si master alloy to the aluminum liquid to adjust the composition, so that the Mg, Cu, and Si element compositions are 0.8 wt.%, 0.9 wt.%, and 0.5 wt.%, respectively; add Al-5Ni master alloy to the aluminum liquid to carry out the first modification of the melt and stir continuously, and let it stand for 10 min to control the Ni content to 0.15 wt.%; then add Al-10Nd master alloy to the aluminum liquid to carry out the second modification of the aluminum liquid and stir continuously to control the Nd content to 0.15 wt.%; then carry out the second refining of the aluminum liquid, introduce inert gas and stir continuously for 15 min. min; then Al-10Zr master alloy was added to the aluminum melt for a third modification and stirring was continued to control the Zr content at 0.4 wt.%; after standing for 5 min, a semi-continuous casting process was used to obtain an alloy ingot with a diameter of 183 mm.

[0073] (2) The alloy ingot was subjected to homogenization heat treatment using a single-stage homogenization process. The ingot was heated from room temperature to 555°C at a heating rate of 2°C / min and held at that temperature for 14 h before being air-cooled.

[0074] (3) The ingot is deformed by hot extrusion at a temperature of 530°C, an extrusion ratio of 25:1, and an extrusion speed of 4 mm / min. The extruded alloy is cooled by water cooling and artificially aged at 175°C for 6 h.

[0075] Example 5

[0076] A method for preparing a high-Fe content aluminum alloy with high comprehensive performance, the specific steps of which are as follows:

[0077] (1) Add 50 kg of scrap aluminum (containing Fe) to the smelting furnace, heat the furnace to 750℃ to melt it, and after the scrap aluminum melts, introduce inert gas into the aluminum liquid and stir continuously for 10~30 min to perform a first refining, and remove the surface residue; take a small sample for composition determination, in which the Fe element mass fraction is 0.79 wt.%, add pure Al, pure Mg, pure Cu, and Al-20Si master alloy to the aluminum liquid to adjust the composition, so that the Mg, Cu, and Si element compositions are 0.8 wt.%, 0.9 wt.%, and 0.5 wt.%, respectively; add Al-10Mn and Al-10Mo master alloy to the aluminum liquid to perform the first modification of the melt and stir continuously, and let it stand for 10 min, and control the Mn and Mo contents to 0.4 wt.% and 0.2 wt.%, respectively. Subsequently, Al-10Y and Al-10Nb master alloys were added to the molten aluminum for a second modification while continuously stirring, with the Y and Nb contents controlled at 0.4 wt.% and 0.3 wt.%, respectively. The molten aluminum was then refined a second time by introducing inert gas and continuously stirring for 15 min. After that, Al-5Ti-B master alloys were added to the molten aluminum for a third modification while continuously stirring, with the Ti content controlled at 0.1 wt.%. After standing for 5 min, a semi-continuous casting process was used to obtain an alloy ingot with a diameter of 183 mm.

[0078] (2) The alloy ingot was subjected to homogenization heat treatment using a single-stage homogenization process. The ingot was heated from room temperature to 555°C at a heating rate of 2°C / min and held at that temperature for 14 h before being air-cooled.

[0079] (3) The ingot is deformed by hot extrusion at a temperature of 530°C, an extrusion ratio of 25:1, and an extrusion speed of 4 mm / min. The extruded alloy is cooled by water cooling and artificially aged at 175°C for 6 h.

[0080] Example 6

[0081] A method for preparing a high-Fe content aluminum alloy with high comprehensive performance, the specific steps of which are as follows:

[0082] (1) Add 50 kg of scrap aluminum (containing Fe) to the smelting furnace, heat the furnace to 750℃ to melt it, and after the scrap aluminum melts, introduce inert gas into the aluminum liquid and stir continuously for 10~30 min to carry out a first refining, and remove the surface residue; take a small sample for composition determination, in which the Fe element mass fraction is 0.68 wt.%, add pure Al, pure Mg, pure Cu, and Al-20Si master alloy to the aluminum liquid to adjust the composition, so that the Mg, Cu, and Si element compositions are 0.8 wt.%, 0.9 wt.%, and 0.5 wt.%, respectively; add Al-10Mn master alloy to the aluminum liquid to carry out the first modification of the melt and stir continuously, and let it stand for 10 min to control the Mn content to 0.7 wt.%; then add Al-5Nb master alloy to the aluminum liquid to carry out the second modification of the aluminum liquid and stir continuously to control the Nb content to 0.1%. The aluminum liquid was then refined a second time by introducing inert gas and stirring continuously for 15 minutes. After that, Al-10Zr master alloy was added to the aluminum liquid for a third modification and stirring continuously to control the Zr content at 0.15 wt.%. After standing for 5 minutes, a semi-continuous casting process was used to obtain an alloy ingot with a diameter of 183 mm.

[0083] (2) The alloy ingot was subjected to homogenization heat treatment using a two-stage homogenization process. It was held at 250℃ for 7 h, then heated to 555℃ at a rate of 2℃ / min and held for 9 h, and then air-cooled.

[0084] (3) The ingot is deformed by hot extrusion at a temperature of 530°C, an extrusion ratio of 25:1, and an extrusion speed of 4 mm / min. The extruded alloy is cooled by water cooling and artificially aged at 175°C for 6 h.

[0085] Comparative Example 1

[0086] A method for preparing an aluminum alloy, comprising the following specific steps:

[0087] (1) Add 50 kg of scrap aluminum (containing Fe) to the smelting furnace and heat the furnace to 750℃ to melt it. After the scrap aluminum melts, introduce inert gas into the aluminum liquid and stir continuously for 10~30 min to carry out the first refining and remove the surface residue. Take a small sample for composition determination. The Fe element mass fraction is 0.73 wt.%. Add pure Al, pure Mg, pure Cu, and Al-20Si master alloy to the aluminum liquid to adjust the composition so that the Mg, Cu, and Si element compositions are 0.8 wt.%, 0.9 wt.%, and 0.5 wt.%, respectively. Then carry out the second refining of the aluminum liquid, introduce inert gas and stir continuously for 15 min. After standing for 5 min, use a semi-continuous process to cast to obtain an alloy ingot with Φ183 mm.

[0088] (2) The alloy ingot was subjected to homogenization heat treatment using a single-stage homogenization process. The ingot was heated from room temperature to 555°C at a heating rate of 2°C / min and held at that temperature for 14 h before being air-cooled.

[0089] (3) The ingot is deformed by hot extrusion at a temperature of 530°C, an extrusion ratio of 25:1, and an extrusion speed of 4 mm / min. The extruded alloy is cooled by water cooling and artificially aged at 175°C for 6 h.

[0090] Comparative Example 2

[0091] Add 50 kg of scrap aluminum (containing Fe) to a smelting furnace and heat the furnace to 750℃ to melt it. After the scrap aluminum melts, introduce inert gas into the molten aluminum and stir continuously for 10-30 min for a first refining process, removing surface residue. Take a small sample for composition analysis, where the Fe element mass fraction is 0.68 wt.%. Add pure Al, pure Mg, pure Cu, and Al-20Si master alloy to the molten aluminum to adjust the composition, making the Mg, Cu, and Si element compositions 0.8 wt.%, 0.9 wt.%, and 0.5 wt.%, respectively. Add Al-10Mn master alloy to the molten aluminum for the first modification and stir continuously, then let it stand for 10 min, controlling the Mn content to 0.7 wt.%. Perform a second refining of the molten aluminum, introducing inert gas and stirring continuously for 15 min. Then add Al-5Ti-B master alloy to the molten aluminum for modification and stir continuously, controlling the Ti content to 0.1 wt.%. Let it stand for 5 minutes. After a period of time, a semi-continuous casting process was used to obtain an alloy ingot with a diameter of 183 mm.

[0092] (2) The alloy ingot was subjected to homogenization heat treatment using a single-stage homogenization process. The ingot was heated from room temperature to 555°C at a heating rate of 2°C / min and held at that temperature for 14 h before being air-cooled.

[0093] (3) The ingot is deformed by hot extrusion at a temperature of 530°C, an extrusion ratio of 25:1, and an extrusion speed of 4 mm / min. The extruded alloy is cooled by water cooling and artificially aged at 175°C for 6 h.

[0094] Test Example 1

[0095] The performance of the aluminum alloys prepared in Examples 1-6 and Comparative Examples 1 and 2 was tested, and the microstructure of the aluminum alloys prepared in Example 1 and Comparative Examples 1 and 2 was analyzed by scanning electron microscopy (SEM). The performance test results are shown in Table 1 below.

[0096] Table 1. Test results of aluminum alloy performance

[0097]

[0098] like Figure 2 As shown, the as-cast microstructure of high-Fe-content 6XXX series aluminum alloys obtained by the method of this invention (adding elements such as Mn, Cr, and Mo) mainly contains the α-Fe phase, while... Figure 3 As shown, the as-cast microstructure of high-Fe-content 6XXX series aluminum alloys obtained without the addition of relevant alloying elements mainly consists of lamellar β-Fe phase, indicating that the method used in this invention alters the form of the Fe-containing phase to some extent. Figure 4 As shown, in Comparative Example 2, the α-Fe phase in the as-cast microstructure of the alloy that did not undergo a second modification is different from that in Example 1 ( Figure 2 It is obviously coarsened.

[0099] Furthermore, as shown in Table 1, the high Fe content 6XXX series aluminum alloy extruded profiles obtained by the method of the present invention have significantly improved strength, elongation, and corrosion resistance, which can meet the application requirements of high-strength 6XXX series aluminum alloys.

[0100] The embodiments described above are only some, not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. The scope of protection of the present invention is determined by the scope claimed in the claims. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a high-Fe-content, high-performance aluminum alloy, characterized in that, Includes the following steps: Step 1) Smelting and casting: First, melt the Fe-containing scrap aluminum; then, introduce inert gas for the first refining; adjust the composition of the main alloying elements; then, add the first type of modifier and the second type of modifier to the aluminum liquid in sequence and stir thoroughly; introduce inert gas for the second refining; then add the third type of modifier and let it stand; cast to obtain alloy ingots; Step 2) Homogenization heat treatment: The alloy ingot obtained in Step 1) is subjected to homogenization heat treatment using a single-stage or double-stage homogenization heat treatment regime. Step 3) Deformation heat treatment: The alloy ingot after homogenization in step 2) is subjected to extrusion hot deformation, followed by water cooling and artificial aging to obtain the final product.

2. The method for preparing a high-Fe-content, high-performance aluminum alloy according to claim 1, characterized in that, Step 1) The control range of the main alloying element composition is: 0.6~1.2 wt.% Mg, 0.6~1.4 wt.% Si, 0.01~0.7 wt.% Cu, and 0.2~1.0 wt.% Fe.

3. The method for preparing a high-Fe-content, high-performance aluminum alloy according to claim 1, characterized in that, Step 1) The first type of modifier is one or more of Al-Mn, Al-Cr, Al-Mo, Al-Co, and Al-Ni master alloys; the second type of modifier is one or more of Al-Nd, Al-Nb, Al-Y, Al-Er, Al-La, and Al-Ce master alloys; and the third type of modifier is one or more of Al-Ti-B and Al-Zr master alloys.

4. The method for preparing a high-Fe-content, high-performance aluminum alloy according to claim 3, characterized in that, When the first type of modifier is added, the amount of Mn added in the Al-Mn master alloy is 50% to 100% of the Fe content in the alloy ingot; the amount of Cr added in the Al-Cr master alloy is 20% to 50% of the Fe content in the alloy ingot; the amount of Mo added in the Al-Mo master alloy is 20% to 50% of the Fe content in the alloy ingot; the amount of Co added in the Al-Co master alloy is 20% to 50% of the Fe content in the alloy ingot; and the amount of Ni added in the Al-Ni master alloy is 20% to 50% of the Fe content in the alloy ingot.

5. The method for preparing a high-Fe-content, high-performance aluminum alloy according to claim 3, characterized in that, When the second type of modifier is added, the amount of Nd added in the Al-Nd master alloy is 10% to 40% of the Fe content in the alloy ingot; the amount of Nb added in the Al-Nb master alloy is 10% to 40% of the Fe content in the alloy ingot; the amount of Y added in the Al-Y master alloy is 20% to 50% of the Fe content in the alloy ingot; the amount of Er added in the Al-Er master alloy is 20% to 80% of the Fe content in the alloy ingot; the amount of La added in the Al-La master alloy is 10% to 50% of the Fe content in the alloy ingot; and the amount of Ce added in the Al-Ce master alloy is 10% to 50% of the Fe content in the alloy ingot.

6. The method for preparing a high-Fe-content, high-performance aluminum alloy according to claim 3, characterized in that, When a third type of modifier is added, the amount of Ti added in the Al-Ti master alloy is 10% to 20% of the Fe content in the alloy ingot; the amount of Zr added in the Al-Zr master alloy is 20% to 50% of the Fe content in the alloy ingot.

7. The method for preparing a high-Fe-content, high-performance aluminum alloy according to claim 1, characterized in that, Step 2) The single-stage homogenization heat treatment process is as follows: the temperature is increased from room temperature to 530-560℃ at a heating rate of 1-3℃ / min, and then held at this temperature for 14-18 hours, followed by air cooling or water cooling. The two-stage homogenization heat treatment process is as follows: the ingot is held at 200~350℃ for 6~10 h, then heated to 530~560℃ at a heating rate of 2~5℃ / min, and held at this temperature for 8~12 h, followed by air cooling or water cooling.

8. The method for preparing a high-Fe-content, high-comprehensive-performance aluminum alloy according to claim 1, characterized in that, The parameters for the extrusion hot deformation in step 3) are as follows: deformation temperature is 500~540℃, extrusion ratio is controlled at 10:1~30:1, and extrusion speed is 2~10 mm / min.

9. The method for preparing a high-Fe-content, high-comprehensive-performance aluminum alloy according to claim 1, characterized in that, Step 3) The artificial aging process is as follows: keep warm at 160~200℃ for 5~10 hours.

10. The aluminum alloy prepared by the method according to any one of claims 1-9, characterized in that, The aluminum alloy is a 6XXX series aluminum alloy.

Images