A method for controlling the Fe-rich phase in recycled aluminum alloys

Abstract

This invention discloses a method for controlling the Fe-rich phase in recycled aluminum alloys, belonging to the field of recycled aluminum alloy technology; it is composed of the following chemical composition: by mass percentage, Si 0.50-0.70%, Fe 0.30-1.30%, Cu 0.20-0.40%, Mn 0.30-1.30%, Mg 0.30-0.50%, Cr 0.20-0.30%, Zn 0.20-0.40%, Ti 0.05-0.10%, with the balance being Al and unavoidable impurities, the total amount of which is less than 0.05%. The control method includes: adding the neutralizing element Mn to the recycled aluminum melt, ensuring that the mass ratio of Mn to Fe is less than 1:1; refining, heat-holding, and casting the melt to obtain a recycled aluminum alloy ingot; homogenizing the ingot to promote the transformation of the acicular β-Fe phase to the fishbone-like α-Fe phase; and then subjecting the sample to hot rolling, solution quenching, cold rolling, and aging treatments to further control the morphology, size, and distribution of the β-Fe phase. This invention can effectively control the harmful β-Fe phase in recycled aluminum alloys, achieving a strength of up to 279.90 MPa and an elongation of 11.75%, with overall performance approaching that of primary aluminum.

Description

Technical Field

[0001] This invention relates to the field of recycled aluminum alloy technology, and in particular to a method for controlling the Fe-rich phase in recycled aluminum alloys. Background Technology

[0002] From an environmental perspective, aluminum's advantage lies in its recyclability. Electrolytic aluminum production is energy-intensive and has a significant environmental impact, while aluminum recycling is low-cost and highly environmentally beneficial. The energy consumption of recycled aluminum is as low as 5% of that of primary aluminum production, showing broad application prospects. Therefore, if recycled aluminum alloys can restore the mechanical properties of primary aluminum, green production of aluminum alloy structural components can be achieved. However, during the recycling process, Fe oxide impurities are inevitably introduced. Furthermore, with the continuous enrichment of Fe, needle-like β-Al5FeSi phases form in the microstructure, severely reducing the mechanical properties of the components, especially the fracture toughness and fatigue life of structural parts. In addition, coarse needle-like β-Fe can hinder the feeding of liquid metal between dendrites during solidification, leading to the formation of micropores, thereby further reducing the fatigue performance of the alloy.

[0003] To address this issue, much research has focused on transforming the harmful needle-like β-Al5FeSi phase into the less harmful α-Al with a fishbone-like morphology. 15 The (Fe,Mn)3Si2(α-Fe) phase. Previous studies have shown that the addition of the neutralizing element Mn can reduce the formation of acicular β-Fe to some extent. This is because Mn and Fe have similar atomic radii, allowing Mn to substitute Fe atoms in the acicular β-Fe phase, thereby promoting the transformation of β-Al5FeSi into α-Al. 15 The transformation of the (Fe,Mn)3Si2 phase. Studies have shown that, with a Mn:Fe ratio of 2:1, harmful β-Fe can be effectively converted into α-Al. 15 (Fe,Mn)3Si2 phase.

[0004] Yu et al. (GJYu, JHPeng, Advanced Materials Research 602-604(2012)590-593) found that when the Mn / Fe ratio is 2:1, under the conditions of melting temperature of 780℃ and holding time of 10 minutes, the needle-like β-Fe can be fully transformed into fishbone-like α-Fe.

[0005] Xu et al. (Z. Xu, X. Zhang, H. Wang, et al. Materials Characterization 168 (2020)) found that when the Mn / Fe mass ratio reached 2:1, needle-like β-Fe was almost not observed at the edge of 6061 twin-roll cast thin plates containing 0.47 wt.% Fe, while a large number of fine α-Al particles were distributed along the grain boundaries. 12 The (Fe,Mn)3Si2 phase alloy exhibits tensile strength of 204.80 MPa and elongation of 17.83%.

[0006] Tseng et al. (C.Tseng, S.Lee, S.Tsai, et al. Journal of Materials Research and Technology 17(9)(2002)2243-2250) reported that when 0.66wt.%Mn was added to an A206 alloy containing 0.30wt.%Fe to achieve an Mn / Fe ratio of 2.2, almost all the lamellar β-Fe was completely transformed into the fishbone-like α-Fe phase.

[0007] However, excessive Mn addition actually leads to an increase in the overall integral number of Fe-rich phases in the alloy, which may offset some of the improvement in alloy plasticity brought about by Mn neutralization. Song et al. (DFSong, YLZhao, Z.Wang, et al. Acta Metallurgica Sinica (English Letters) 35(1)(2021) 163-175) studied the evolution of Fe-rich phases in Al-7.0Si-1.2Fe alloys with different Mn additions and found that excessive Mn addition increased the coarse α-Al in the alloy. 15 The volume fraction of the (Fe,Mn)3Si2 phase reduces the ductility of the alloy.

[0008] Therefore, with limited Mn addition (Mn / Fe ratio less than 1:1), and with ideal β-Fe modification effect, without forming coarse Fe-rich phases, it is an ideal choice for regulating the microstructure and properties of recycled aluminum alloys.

[0009] Currently, there are many experimental studies on the influence of Fe-rich phases in Al-Si casting alloys, but fewer experimental studies on the influence of Al-Fe-Si intermetallic compounds on the mechanical properties of wrought aluminum alloys. To optimize the size and distribution of Fe-rich phases in recycled aluminum alloys, many scholars have studied the formation and evolution of Fe-rich phases in various processing steps. Li et al. (Y.Li, L.Arnberg. Materials science engineering: A347(1-2)(2003)130-135) found that Fe-rich phase dissolution fracture and phase transformation occur during homogenization treatment. Alexander et al. (D.Alexander, A.Greer. Materials science technology 21(8)(2005)955-960) observed the fracture of Fe-rich phases during heat treatment. Hamerton et al. (R.Hamerton, H.Cama, M.Meredith. Materials scienceforum, Trans Tech Publ, 2000, pp.143-154) found that the morphology of Fe-rich phases has a significant impact on the fracture of Fe phases during rolling. The results show that homogenization treatment of ingots can not only eliminate microsegregation, but also promote the transformation of needle-like β-Fe phase into fishbone-like α-Fe phase in the microstructure. This transformed α-Fe phase is beneficial to improving the subsequent processing performance of the alloy.

[0010] During the rolling process, due to the deformation of the surrounding matrix, the second phase in the alloy will be subjected to local mechanical loads, leading to its fracture. Hot rolling to break up the coarse Fe-rich phase is an important development in industrial production.

[0011] Therefore, with limited Mn addition (Mn / Fe less than 1:1), it is urgent to determine an optimized homogenization and hot deformation process to accelerate the dissolution and transformation of the harmful β-Fe phase, thereby efficiently controlling the morphology, size and distribution of the harmful β-Fe phase in recycled aluminum alloys, and improving the microstructure and properties of recycled aluminum alloys to meet the needs of their commercial applications. Summary of the Invention

[0012] This application provides a method for controlling the Fe-rich phase in recycled aluminum alloys. Under limited Mn addition (Mn / Fe less than 1:1), by optimizing homogenization and hot deformation processes, the harmful needle-like β-Fe phase in recycled aluminum alloys can be effectively transformed into fishbone-like α-Fe phases. Furthermore, the morphology, size, and distribution of the Fe-rich phase can be effectively controlled to refine the alloy microstructure and improve plastic processing.

[0013] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0014] A recycled aluminum alloy comprises the following chemical composition by mass percentage: Si 0.50–0.70%, Fe 0.30–1.30%, Cu 0.20–0.40%, Mn 0.30–1.30%, Mg 0.30–0.50%, Cr 0.20–0.30%, Zn 0.20–0.40%, Ti 0.05–0.10%, with the balance being Al and unavoidable impurities, the total amount of said unavoidable impurities being less than 0.05%.

[0015] Preferably, the composition comprises the following chemical components: Si 0.55–0.70%, Fe 0.50–1.0%, Cu 0.30–0.40%, Mn 0.50–1.0%, Mg 0.40–0.50%, Cr 0.20–0.25%, Zn 0.20–0.30%, Ti 0.05–0.10%, with the balance being Al and unavoidable impurities, the total amount of which is less than 0.05%.

[0016] Preferably, the mass ratio of Mn to Fe added to the recycled aluminum melt is less than 1:1.

[0017] Preferably, the main microstructure of the recycled aluminum alloy is fishbone-like α-Fe.

[0018] The present invention also provides a method for preparing recycled aluminum alloy and controlling the Fe-rich phase, comprising the following steps:

[0019] S1. Weigh the raw materials according to the composition of the recycled aluminum alloy and preheat the raw materials.

[0020] S2. Add the preheated raw materials from step S1 to an electric resistance furnace for melting, introduce intermediate alloys other than aluminum-titanium-boron intermediate alloys and optional aluminum-magnesium intermediate alloys, stir and melt to obtain alloy liquid.

[0021] S3. After refining, degassing and removing slag from the alloy liquid, add aluminum-titanium-boron master alloy and optional aluminum-magnesium master alloy. After all the master alloys are completely melted, keep it at the temperature for 20-30 minutes, and then pour it to obtain a recycled aluminum alloy ingot.

[0022] S4. The recycled aluminum alloy ingot is subjected to a two-stage homogenization treatment at 490-540℃.

[0023] S5. The homogenized recycled aluminum alloy ingot is hot rolled at an inlet temperature of 520-530℃ and an outlet temperature of 140-160℃ to obtain recycled aluminum alloy sheet.

[0024] S6. The recycled aluminum alloy sheet is subjected to a two-stage solution treatment at 490-540℃, and then water quenched.

[0025] S7. The water-quenched plate is cold-rolled and then aged to obtain a recycled aluminum alloy sample.

[0026] Preferably, the preparation method further includes: in S1, preheating the raw materials, mold and graphite crucible at 200°C for 1-2 hours.

[0027] Preferably, in S3, the casting conditions include: a temperature of 730-740℃ and a casting speed of 80-100mm / min.

[0028] Preferably, in step S4, the homogenization process includes: first keeping the temperature at 490-500℃ for 4-6 hours, and then keeping the temperature at 530-540℃ for 6-12 hours.

[0029] Preferably, in S5, hot rolling results in a rolling deformation of 30-40%; and / or, the hot rolling speed is 1-1.5 m / s.

[0030] Preferably, in step S6, the two-stage solution treatment process includes: first, maintaining the temperature at 490-500℃ for 2-4 hours, and then maintaining the temperature at 530-540℃ for 6-8 hours.

[0031] Preferably, in S7, the cold rolling results in a cold rolling deformation of 20-30%.

[0032] Preferably, the aging treatment conditions include: treatment at 170-175℃ for 8-16 hours, preferably 8 hours.

[0033] The beneficial effects of the above-described technical solution of the present invention are as follows:

[0034] The above-described method for controlling the Fe-rich phase in recycled aluminum alloys is simple, efficient, low-cost, and easy to promote. Its specific beneficial effects can be categorized into the following three aspects:

[0035] 1. This invention employs a limited addition of the neutralizing element Mn (Mn / Fe ratio less than 1:1), which avoids the formation of coarse Fe-rich phases in the alloy structure and the loss of the improvement in alloy plasticity brought about by Mn neutralization.

[0036] 2. The present invention optimizes a suitable homogenization process that can promote the transformation of harmful needle-like β-Fe phase in the matrix structure into fishbone-like α-Fe phase, thereby improving the hot working properties of the alloy.

[0037] 3. By combining hot deformation process, the morphology, size and distribution of harmful phase β-Fe in recycled aluminum alloy can be effectively controlled, thereby effectively improving the strength and plasticity of recycled aluminum alloy and further meeting the performance requirements of its industrial applications.

[0038] The recycled aluminum alloy of the present invention has a strength of up to 279.75 MPa and an elongation of up to 11.75%, as shown in Test Example Table 1. The various properties of the alloy are significantly improved compared to the as-cast state, and its comprehensive performance is close to that of primary aluminum. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a process route diagram in an embodiment of the present invention;

[0041] Figure 2 SEM images of the as-cast, homogenized, and deformed microstructures of a recycled aluminum alloy according to Embodiment 1 of the present invention are shown. Specifically: (a) is a metallographic image of the as-cast microstructure, and (a1) is a magnified view of (a); (b) is a metallographic image of the homogenized microstructure, and (b1) is a magnified view of (b); (c) is a metallographic image of the deformed microstructure, and (c1) is a magnified view of (c).

[0042] Figure 3 These are the engineering stress-engineering strain curves corresponding to the as-cast, homogenized, and deformed alloys in Embodiment 1 of the present invention. Detailed Implementation

[0043] To make the technical problems, solutions, and advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated; they can be combined to achieve better technical effects. In the accompanying drawings of the following embodiments, the same reference numerals in each drawing represent the same features and can be applied to different embodiments.

[0044] This invention provides a recycled aluminum alloy composed of the following chemical composition: by mass percentage, Si 0.50–0.70%, Fe 0.30–1.30%, Cu 0.20–0.40%, Mn 0.30–1.30%, Mg 0.30–0.50%, Cr 0.20–0.30%, Zn 0.20–0.40%, Ti 0.05–0.10%, with the balance being Al and unavoidable impurities, the total amount of which is less than 0.05%.

[0045] In some embodiments, the composition comprises the following chemical components: Si 0.55–0.70%, Fe 0.50–1.0%, Cu 0.30–0.40%, Mn 0.50–1.0%, Mg 0.40–0.50%, Cr 0.20–0.25%, Zn 0.20–0.30%, Ti 0.05–0.10%, with the balance being Al and unavoidable impurities, the total amount of which is less than 0.05%.

[0046] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with specific embodiments.

[0047] Example 1

[0048] The method for controlling the Fe-rich phase in recycled aluminum alloy described in this embodiment is characterized by comprising the following components by mass percentage: Si 0.56 wt.%, Fe 0.85 wt.%, Cu 0.35 wt.%, Mn 0.80 wt.%, Mg 0.43 wt.%, Cr 0.22 wt.%, Zn 0.28 wt.%, Ti 0.06 wt.%, with the remainder being Al and unavoidable impurities.

[0049] A method for preparing recycled aluminum alloy and controlling the Fe-rich phase includes the following steps:

[0050] S1. Raw material selection: The recycled aluminum alloy composition is formulated according to the above proportions. The raw material is an intermediate aluminum alloy of pure aluminum and other raw materials. Among them, the Mg element needs to be selected as an aluminum-magnesium intermediate alloy considering a 10% burn-off.

[0051] S2. Pretreatment: Preheat the raw materials, mold, and graphite crucible at 200℃ for 1 hour;

[0052] S3. Melting: The raw materials pretreated in step S2, pure aluminum and aluminum-silicon, aluminum-iron, aluminum-manganese, aluminum-copper, aluminum-zinc and aluminum-chromium master alloys are added into the furnace in sequence. The furnace temperature is raised to 730℃ and held for 30 minutes to obtain the melt.

[0053] S4. Aluminum liquid treatment: After thoroughly stirring the melt from step S3, add 0.8 wt.% of slag remover and 0.3 wt.% of refining agent by mass of melt. Refine for 13 minutes, remove the slag, and then let stand for 25 minutes.

[0054] S5. Addition of intermediate alloy: Add aluminum-titanium-boron intermediate alloy and optional aluminum-magnesium intermediate alloy to the melt from which the slag has been removed in step S4, and stir thoroughly.

[0055] S6. Casting: After the intermediate alloy added in step S5 has completely melted, keep it at the temperature for 30 minutes, and then cast it at a temperature of 730℃ and a casting speed of 90mm / min. After cooling, take out the recycled aluminum alloy ingot.

[0056] S7. The recycled aluminum alloy ingot is subjected to homogenization treatment by first holding it at 490℃ for 4 hours and then holding it at 530℃ for 6 hours.

[0057] S8. The homogenized recycled aluminum alloy ingot is hot rolled at an inlet temperature of 520℃, an outlet temperature of 150℃, and a rolling speed of 1m / s to obtain a plate with a hot rolling deformation of 30%.

[0058] S9. The hot-rolled sheet is subjected to a two-stage solution treatment: first, it is kept at 490℃ for 2 hours, and then at 530℃ for 6 hours, followed by water quenching.

[0059] S10. The water-quenched plate is cold-rolled, and the cold-rolling deformation is 20%.

[0060] S11. The cold-rolled sheet is subjected to aging treatment at 170℃ for 8 hours to obtain a recycled aluminum alloy sample.

[0061] Among them, such as Figure 2 As shown in (a), the as-cast microstructure of the prepared recycled aluminum alloy mainly consists of acicular β-Al5FeSi phase and T-shaped α-Al phase. 15 The structure consists of the (Fe,Mn)3Si2 phase, and a locally enlarged view of the β-Fe phase is shown in Figure (a1); Figure 2 As shown in (b), after homogenization treatment, the β-Al5FeSi phase exhibits dissolution at its tips and outer edges, resulting in a smaller size. Simultaneously, α-Al... 15 The (Fe,Mn)3Si2 phase nucleates and grows on the surface of the β-Al5FeSi phase, such as Figure 2 As shown in (b1); Figure 2As shown in (c), after the final cold rolling and aging process, the coarse, lamellar β-Fe phase in the matrix is ​​significantly broken into short, rod-shaped particles. The cutting effect of β-Fe on the matrix is ​​significantly reduced, which helps to improve the strength and plasticity of the alloy. Simultaneously, the electron scattering effect of the broken β-Fe phase is further reduced, contributing to the improvement of the alloy's conductivity. This invention, under limited Mn addition (Mn / Fe less than 1:1), accelerates the dissolution and transformation of β-Fe by optimizing homogenization and hot deformation processes, and efficiently controls the morphology, size, and distribution of the β-Fe phase in the alloy.

[0062] The recycled aluminum alloy prepared by this invention has a strength of up to 279.75 MPa, an elongation of up to 11.75%, and a conductivity of 41.00% IACS (see Test Example Table 1). The alloy's various properties are significantly improved compared to the as-cast state, and its comprehensive performance is close to that of primary aluminum, which is conducive to the large-scale commercial application of recycled aluminum alloys.

[0063] Example 2

[0064] The method for controlling the Fe-rich phase in recycled aluminum alloy described in this embodiment is characterized by comprising the following components by mass percentage: Si 0.60 wt.%, Fe 0.80 wt.%, Cu 0.30 wt.%, Mn 0.70 wt.%, Mg 0.40 wt.%, Cr 0.20 wt.%, Zn 0.20 wt.%, Ti 0.05 wt.%, with the remainder being Al and unavoidable impurities.

[0065] A method for preparing recycled aluminum alloy and controlling the Fe-rich phase includes the following steps:

[0066] S1. Raw material selection: The recycled aluminum alloy composition is formulated according to the above proportions. The raw material is an intermediate aluminum alloy of pure aluminum and other raw materials. Among them, the Mg element needs to be selected as an aluminum-magnesium intermediate alloy considering a 10% burn-off.

[0067] S2. Pretreatment: Preheat the raw materials, mold, and graphite crucible at 200℃ for 1 hour;

[0068] S3. Melting: The raw materials pretreated in step S2, pure aluminum and aluminum-silicon, aluminum-iron, aluminum-manganese, aluminum-copper, aluminum-zinc and aluminum-chromium master alloys are added into the furnace in sequence. The furnace temperature is raised to 730℃ and held for 30 minutes to obtain the melt.

[0069] S4. Aluminum liquid treatment: After thoroughly stirring the melt from step S3, add 0.8 wt.% of slag remover and 0.3 wt.% of refining agent by mass of melt. Refine for 13 minutes, remove the slag, and then let stand for 25 minutes.

[0070] S5. Addition of intermediate alloy: Add aluminum-titanium-boron intermediate alloy and optional aluminum-magnesium intermediate alloy to the melt from which the slag has been removed in step S4, and stir thoroughly.

[0071] S6. Casting: After the intermediate alloy added in step S5 has completely melted, keep it at the temperature for 30 minutes, and then cast it at a temperature of 730℃ and a casting speed of 90mm / min. After cooling, take out the recycled aluminum alloy ingot.

[0072] S7. The recycled aluminum alloy ingot is subjected to homogenization treatment by first holding it at 490℃ for 4 hours and then holding it at 530℃ for 6 hours.

[0073] S8. The homogenized recycled aluminum alloy ingot is hot rolled at an inlet temperature of 520℃, an outlet temperature of 150℃, and a rolling speed of 1m / s to obtain a plate with a hot rolling deformation of 30%.

[0074] S9. The hot-rolled sheet is subjected to a two-stage solution treatment: first, it is kept at 490℃ for 2 hours, and then at 530℃ for 6 hours, followed by water quenching.

[0075] S10. The water-quenched plate is cold-rolled, and the cold rolling deformation is 20%.

[0076] S11. The cold-rolled sheet is subjected to aging treatment at 170℃ for 8 hours to obtain a recycled aluminum alloy sample.

[0077] Example 3

[0078] The method for controlling the Fe-rich phase of a regenerated Al-Mg-Si alloy described in this embodiment is characterized by the following composition by mass percentage: Si 0.70 wt.%, Fe 1.0 wt.%, Cu 0.40 wt.%, Mn 0.90 wt.%, Mg 0.50 wt.%, Cr 0.25 wt.%, Zn 0.30 wt.%, Ti 0.10 wt.%, with the remainder being Al and unavoidable impurities.

[0079] A method for preparing recycled aluminum alloy and controlling the Fe-rich phase includes the following steps:

[0080] S1. Raw material selection: The recycled aluminum alloy composition is formulated according to the above proportions. The raw material is an intermediate aluminum alloy of pure aluminum and other raw materials. Among them, the Mg element needs to be selected as an aluminum-magnesium intermediate alloy considering a 10% burn-off.

[0081] S2. Pretreatment: Preheat the raw materials, mold, and graphite crucible at 200℃ for 1 hour;

[0082] S3. Melting: The raw materials pretreated in step S2, pure aluminum and aluminum-silicon, aluminum-iron, aluminum-manganese, aluminum-copper, aluminum-zinc and aluminum-chromium master alloys are added into the furnace in sequence. The furnace temperature is raised to 730℃ and held for 30 minutes to obtain the melt.

[0083] S4. Aluminum liquid treatment: After thoroughly stirring the melt from step S3, add 0.8 wt.% of slag remover and 0.3 wt.% of refining agent by mass of melt. Refine for 13 minutes, remove the slag, and then let stand for 25 minutes.

[0084] S5. Addition of intermediate alloy: Add aluminum-titanium-boron intermediate alloy and optional aluminum-magnesium intermediate alloy to the melt from which the slag has been removed in step S4, and stir thoroughly.

[0085] S6. Casting: After the intermediate alloy added in step S5 has completely melted, keep it at the temperature for 30 minutes, and then cast it at a temperature of 730℃ and a casting speed of 90mm / min. After cooling, take out the recycled aluminum alloy ingot.

[0086] S7. The recycled aluminum alloy ingot is subjected to homogenization treatment by first holding it at 490℃ for 4 hours and then holding it at 530℃ for 6 hours.

[0087] S8. The homogenized recycled aluminum alloy ingot is hot rolled at an inlet temperature of 520℃, an outlet temperature of 150℃, and a rolling speed of 1m / s to obtain a plate with a hot rolling deformation of 30%.

[0088] S9. The hot-rolled sheet is subjected to a two-stage solution treatment: first, it is kept at 490℃ for 2 hours, and then at 530℃ for 6 hours, followed by water quenching.

[0089] S10. The water-quenched plate is cold-rolled, and the cold rolling deformation is 20%.

[0090] S11. The cold-rolled sheet is subjected to aging treatment at 170℃ for 8 hours to obtain a recycled aluminum alloy sample.

[0091] Test case

[0092] The tensile strength, elongation, electrical conductivity, and hardness of the as-cast, homogenized, and deformed alloys in Example 1 were measured, and the results are shown in Table 1.

[0093] Table 1. Comprehensive properties of the as-cast, homogenized, and deformed alloys in Example 1.

[0094] Example 1 YS(MPa) UTS (MPa) EL% HV %IACS As-cast 117.77 196.92 10.88 60.30 27.15 homogenized state 94.27 169.92 13.68 54.40 36.56 Transformation 255.63 279.90 11.75 94.25 41.00

[0095] By comparing the mechanical properties of the as-cast, homogenized, and deformed alloys corresponding to Example 1 in the test cases, it can be concluded that, under limited Mn addition (Mn / Fe less than 1:1), by optimizing the homogenization and hot deformation processes, the dissolution and transformation of the β-Fe phase are accelerated, achieving efficient control over the morphology, size, and distribution of the harmful β-Fe phase in the recycled aluminum alloy, and significantly improving the strength and plasticity of the alloy. The present invention demonstrates a significant effect in controlling the Fe-rich phase in a recycled aluminum alloy.

[0096] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for controlling the Fe-rich phase in recycled aluminum alloys, characterized in that, The recycled aluminum alloy is composed of the following chemical composition by mass percentage: Si 0.50–0.70%, Fe 0.80–1.30%, Cu 0.20–0.40%, Mn 0.30–1.30%, Mg 0.30–0.50%, Cr 0.20–0.30%, Zn 0.20–0.40%, Ti 0.05–0.10%, with the balance being Al and unavoidable impurities, the total amount of which is less than 0.05%; and the mass ratio of Mn to Fe in the recycled aluminum melt is less than 1:1; the method includes the following steps: S1. Weigh the raw materials according to the composition of the recycled aluminum alloy. The raw materials include pure aluminum, aluminum iron, aluminum manganese, aluminum chromium, aluminum titanium boron and other intermediate alloys of required elements, and preheat the raw materials. S2. Add the preheated raw materials from step S1 to an electric resistance furnace for melting, introduce intermediate alloys other than aluminum-titanium-boron intermediate alloys and optional aluminum-magnesium intermediate alloys, stir and melt to obtain alloy liquid. S3. After refining, degassing and removing slag from the alloy liquid, add aluminum-titanium-boron master alloy and optional aluminum-magnesium master alloy. After all the master alloys are completely melted, keep it at the temperature for 20-30 minutes, and then pour it to obtain a recycled aluminum alloy ingot. S4. The recycled aluminum alloy ingot is subjected to a two-stage homogenization treatment at 490-540℃. S5. The homogenized recycled aluminum alloy ingot is hot rolled at an inlet temperature of 520-530℃ and an outlet temperature of 140-160℃ to obtain recycled aluminum alloy sheet. S6. The recycled aluminum alloy sheet is subjected to a two-stage solution treatment at 490-540℃, and then water quenched. S7. The water-quenched plate is cold-rolled and then aged to obtain a recycled aluminum alloy sample.

2. The chemical composition of the recycled aluminum alloy according to claim 1, characterized in that, It is composed of the following chemical components: Si 0.55–0.70%, Fe 0.80–1.0%, Cu 0.30–0.40%, Mn 0.50–1.0%, Mg 0.40–0.50%, Cr 0.20–0.25%, Zn 0.20–0.30%, Ti 0.05–0.10%, with the balance being Al and unavoidable impurities, the total amount of which is less than 0.05%.

3. The method for controlling the Fe-rich phase in recycled aluminum alloys according to claim 1 or 2, characterized in that, The main microstructure of the recycled aluminum alloy is fishbone-like α-Al. 15 (Fe,Mn)3Si2 phase.

4. The control method according to claim 1, characterized in that, The control method also includes: in S1, preheating the raw materials, mold and graphite crucible at 200°C for 1-2 hours.

5. The control method according to claim 1, characterized in that, In S4, the two-stage homogenization process includes: first, maintaining the temperature at 490-500℃ for 4-6 hours, and then maintaining the temperature at 530-540℃ for 6-12 hours.

6. The control method according to claim 1, characterized in that, In S5, hot rolling results in a rolling deformation of 30-40%; and / or, the hot rolling speed is 1-1.5 m / s.

7. The control method according to claim 1, characterized in that, In S6, the two-stage solution treatment process includes: first, holding at 490-500℃ for 2-4 hours, and then holding at 530-540℃ for 6-8 hours.

8. The control method according to claim 1, characterized in that, In S7, the cold rolling results in a cold rolling deformation of 20-30%; the aging treatment conditions include: artificial aging treatment at 170-175℃ for 8-16 hours.

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