Treatment method for mixed secondary aluminum waste and aluminum alloy prepared through treatment method

Abstract

The invention relates to the technical field of secondary aluminum production, in particular to a treatment method of mixed secondary aluminum waste and aluminum alloy prepared from the mixed secondary aluminum waste, and the mixed secondary aluminum waste in the method comprises, by weight, 40-60% of main materials, 10-30% of functional materials, 15-28% of dilution materials and 2-5% of balance materials. The sum of the weight percentages of the main material and the functional material is 70-80%, and the sum of the weight percentages of the diluting material and the balancing material is 20-30%; the functional material is thin-wall aluminum alloy waste with the wall thickness being 0.10-0.30 mm and the specific surface area being 3 * 10 <-3 >-5 * 10 <-3 > m < 2 > / g. According to the regenerated aluminum alloy prepared through the method, the cost of per ton of aluminum is reduced by 3.0-6.6%, the water yield and the hydrogen content meet the industrial standard, the yield strength is larger than or equal to 265 MPa, the tensile strength is larger than or equal to 305 MPa, the elongation is larger than 10%, and the regenerated aluminum alloy is a high-quality regenerated aluminum product capable of replacing original aluminum.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of secondary aluminum production, in particular to a mixed secondary aluminum scrap processing method and an aluminum alloy prepared therefrom. BACKGROUND

[0002] The secondary aluminum industry has become a core part of the green transformation of the non-ferrous metal industry. The consumption of 6-series aluminum alloys accounts for more than 50% of the deformed aluminum alloy market. Compared with traditional primary aluminum smelting, secondary 6-series aluminum alloys can reduce energy consumption by more than 70% and carbon emissions by 90%. Currently, the waste material for secondary aluminum production is a single category, such as door and window profile waste, which accounts for more than 60%, but the cost per ton of aluminum is still high. If mixed scrap is used as the waste material for secondary aluminum production, the cost will be reduced, but it will also lead to problems such as oxidation loss, aluminum liquid quality, organizational defects, and product performance control. For example, the increase in the proportion of thin-walled scrap will cause the specific surface area to increase by 5-8 times, and the impurity Fe content will increase by 50%.

[0003] In view of the problems of aluminum alloy scrap oxidation loss and the like, relevant patents have proposed solutions. CN102140579B proposes a low-temperature immersion melting process method for secondary aluminum, which increases the direct yield of aluminum alloy products by 1-5%, but this method cannot avoid the exposure of some scrap pieces and is not suitable for thin-walled (thickness <3mm) scrap with a large specific surface area.

[0004] In view of the organization regulation of secondary aluminum alloy products, existing technologies propose solutions from the homogenization heat treatment system. Chinese patent CN202410080959.4 discloses a secondary aluminum homogenization system: first at 490-500℃ for 4-6h, and then at 530-540℃ for 6-12h. This two-stage homogenization system does not set a low-temperature pretreatment stage, which makes it difficult to release casting residual stress, leading to cracks during subsequent processing. Chinese patent CN202311170993.2 discloses a secondary aluminum homogenization system: 320-350℃×1-1.5h→450-500℃×50-60min→180-220℃×2-3h. This system only needs 5.5h, but stress concentration is easy to occur in the first and second stages, and the third stage causes Mg2Si phase to precipitate prematurely, resulting in a final tensile strength of <280MPa, which is 30-50MPa lower than the standard for 6-series primary aluminum.

[0005] The above-mentioned technologies all have the limitation of "single-point optimization": the oxidation control technology does not adapt to the ratio characteristics of mixed scrap, and the homogenization process does not consider the influence of oxidation inclusions on the organization. Oxidation loss and organizational regulation are treated separately, and it is not realized that oxidation inclusions will increase the precipitation amount on the grain boundary by 30%, further deteriorating the processing performance.

[0006] In view of the above, there is an urgent need for a mixed secondary aluminum scrap processing method and an aluminum alloy prepared therefrom. SUMMARY

[0007] The present application aims to solve the technical problem of how to provide a processing method of mixed recycled aluminum scrap and an aluminum alloy prepared by the method.

[0008] To achieve the above-mentioned purpose, the first aspect of the present application provides a processing method of mixed recycled aluminum scrap, wherein the processing method comprises:

[0009] scrap pretreatment, melting and casting, homogenization, extrusion, artificial aging;

[0010] The raw materials of the mixed recycled aluminum scrap and the weight percentage thereof are: 40-60% of main material, 10-30% of functional material, 15-28% of dilution material, and 2-5% of balance material, wherein the sum of the weight percentage of the main material and the functional material is 70-80%, and the sum of the weight percentage of the dilution material and the balance material is 20-30%;

[0011] The components in the main material and the weight percentage thereof are: Si content of 0.20-0.70%; Mg content of 0.45-0.70%; Fe content of 0.10-0.25%; single content of other impurity elements ≤0.05%; total content of other impurity elements ≤0.15%; and the balance is Al;

[0012] The melting point of the main material is ≥650℃;

[0013] The functional material is a thin-walled aluminum alloy scrap with a wall thickness of 0.10-0.30mm, a specific surface area of 3×10 -3 -5×10 -3 m 2 / g;

[0014] The components in the functional material and the weight percentage thereof are: Mg content of 1.65-2.45%; Mn content of 0.50-1.00%; Cu content of 0.03-0.17%; Fe content of 0.30-0.60%; single content of other impurity elements ≤0.05%; total content of other impurity elements ≤0.15%; and the balance is Al;

[0015] The dilution material is a primary aluminum ingot with a purity of ≥99.70%;

[0016] The balance material includes at least one of industrial silicon, pure magnesium ingot, Al-20%Mn intermediate alloy, Al-20%Cr intermediate alloy, Al-60%Cu intermediate alloy, Al-5%V intermediate alloy, and aluminum titanium boron wire AlTi5B1.

[0017] The second aspect of the present application provides an aluminum alloy prepared by the above-mentioned processing method of mixed recycled aluminum scrap, wherein the components in the aluminum alloy and the weight percentage thereof are:

[0018] Si content is 0.2-1.3%;

[0019] Mn content is ≤1.0%;

[0020] Mg content is 0.4-1.2%;

[0021] Ti content is ≤0.25%;

[0022] Fe content is ≤0.50%;

[0023] V content is 0.05-0.20%;

[0024] Other impurity elements are ≤0.05% individually;

[0025] Other impurity elements are ≤0.15% in total;

[0026] The balance is Al.

[0027] The beneficial effects of the present application are:

[0028] 1. The melting process of the recycled aluminum cooperates with hydraulic depression, greatly shortens the exposure time of waste materials, reduces the burning loss, and the water yield and hydrogen absorption amount meet the industry requirements.

[0029] 2. The present application realizes gradient diffusion through multi-stage temperature regulation, realizes organization optimization, and meets the application requirements of automobile materials.

[0030] 3. Economic batching-dynamic oxidation control-homogenization synergistically significantly improves the mechanical properties of recycled aluminum in T6 state, approaches the level of original aluminum products such as automobile structural parts, changes the current situation that recycled aluminum is only used for low-end castings, and improves the product added value of recycled aluminum.

[0031] 4. The present application reduces the raw material cost of recycled aluminum by 3-6.6% through mixed addition of waste materials and reasonable design of the ratio. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a schematic diagram of the microstructure sample position of the ingot;

[0033] Figure 2 It is a schematic diagram of the static tensile sample size;

[0034] Figure 3 It is a microstructure diagram of the cast bar after homogenization of Example 2;

[0035] Figure 4 It is a microstructure diagram of the cast bar after homogenization of Comparative Example 6. DETAILED DESCRIPTION

[0036] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the properties. The endpoints of the ranges and any values are provided as approximations only, and the ranges and values should be construed to be open-ended ranges and values in order to account for variations and / or imprecise measurements.

[0037] In the prior art, the recycling aluminum technology has the disadvantage of single-point optimization, which affects the performance of the processed aluminum alloy material.

[0038] In the present application, the inventors have found that, by controlling the recycled aluminum raw material and adjusting the processing technology, high-quality recycled aluminum products that can replace primary aluminum can be obtained, with a water yield and hydrogen content meeting industry standards, a yield strength of ≥265 MPa, a tensile strength of ≥305 MPa, and an elongation of >10%.

[0039] To achieve this goal, the inventors have tried to optimize the composition of the recycled aluminum raw material and the processing technology, and have found that, by using a specific recycled aluminum raw material composition and casting process, the above-mentioned goal can be achieved. Furthermore, a specific homogenization process makes the performance of the aluminum alloy more excellent.

[0040] The first aspect of the present application provides a processing method for mixed recycled aluminum scrap, wherein the processing method comprises:

[0041] Scrap pretreatment, casting, homogenization, extrusion, artificial aging;

[0042] The raw materials of the mixed recycled aluminum scrap and their weight percentages are as follows: 40-60% of main material, 10-30% of functional material, 15-28% of dilution material, and 2-5% of balance material, wherein the sum of the weight percentages of the main material and the functional material is 70-80%, and the sum of the weight percentages of the dilution material and the balance material is 20-30%;

[0043] The components in the main material and their weight percentages are as follows: Si content of 0.20-0.70%; Mg content of 0.45-0.70%; Fe content of 0.10-0.25%; individual content of other impurity elements ≤0.05%; total content of other impurity elements ≤0.15%; and the balance being Al;

[0044] The melting point of the main material is ≥650℃;

[0045] The functional material is a thin-walled aluminum alloy scrap with a wall thickness of 0.10-0.30 mm, a specific surface area of 3×10 -3 -5×10 -3 m 2 / g, and a length of 5-20 mm;

[0046] The components and weight percentage of the functional material are as follows: Mg content is 1.65-2.45%; Mn content is 0.50-1.00%; Cu content is 0.03-0.17%; Fe content is 0.30-0.60%; single content of other impurity elements is ≤0.05%; total content of other impurity elements is ≤0.15%; and the balance is Al;

[0047] The dilution material is an original aluminum ingot with purity ≥99.70%;

[0048] The balance material comprises at least one of industrial silicon, pure magnesium ingot, Al-20% Mn intermediate alloy, Al-20% Cr intermediate alloy, Al-60% Cu intermediate alloy, Al-5% V intermediate alloy and aluminum titanium boron wire AlTi5B1.

[0049] In the application, the main material is a high melting point waste material, which can be a surface treatment building profile aluminum alloy waste material.

[0050] According to the application, the waste material pretreatment comprises: soaking the raw material in a 5-8wt% NaOH solution for 10-15min, mechanically grinding and stripping the electrophoretic coating, magnetically removing iron impurities, crushing the main material, compacting the main material and the functional material.

[0051] In the application, the compacting of the main material and the functional material reduces the volume gap during smelting, facilitating the hydraulic pressing operation in the melting and casting process.

[0052] According to the application, the melting and casting comprises: furnace temperature is 740-760℃, inputting raw materials, refining, slagging, degassing, filtering and casting.

[0053] In the application, 99.9% pure argon and granular refining agent are used for degassing refining, the melt temperature is 730-760℃, the argon flow is 10-15L / min, the refining agent dosage is 2-3kg / ton of aluminum, and the surface dross is removed by mechanical slagging method; the unit standing time is 1-1.5m 3 / h.

[0054] The filtering adopts a graphite rotor degassing machine with degassing efficiency ≥50%, a double-stage filtering device, a foam ceramic filter plate and 30ppi+50ppi.

[0055] When the ingot diameter is 80mm, the casting speed is 150-170mm / min.

[0056] According to the application, the sequence of inputting raw materials is: inputting the main material first, then inputting the functional material, and finally inputting the dilution material and the balance material.

[0057] In the application, after the functional material is inputted, the melt chemical composition is sampled and detected, the dilution material and the balance material input amount are calculated according to the gap between the alloy elements and the target composition.

[0058] According to the present application, the main material is put in 4-8 times, and the mass ratio of the first time to the rest times is 2:1-2.

[0059] According to the present application, the main material is put in 4-8 times, and the mass ratio of the first time to the rest times is 2:1-2.

[0060] In the present application, in order to ensure that the main material and the functional material are completely immersed, and the internal material is not affected by the melt buoyancy and exposed to air again, the down-pressing time is set to 30-60s. If the time is too short (<30s), the immersion is insufficient, and if the time is too long (>60s), the energy consumption of the hydraulic system is increased.

[0061] During the process of putting in the main material each time, the stirring is performed 1-2 times.

[0062] According to the present application, after the main material is put in, the melt temperature is 670-700℃, the functional material is put in, and the put-in functional material is pressed into the aluminum melt surface by 50-100mm by hydraulic pressure, and is maintained for 30-60s.

[0063] During the process of putting in the functional material, the stirring is performed 1-2 times.

[0064] According to some preferred embodiments of the present application, when the radius of the main material is ≥30mm, the hydraulic pressure is pressed into the aluminum melt surface by 100mm, and when the radius of the main material is <30mm, the hydraulic pressure is pressed into the aluminum melt surface by 50mm.

[0065] According to some preferred embodiments of the present application, when the radius of the functional material is ≥30mm, the hydraulic pressure is pressed into the aluminum melt surface by 100mm, and when the radius of the functional material is <30mm, the hydraulic pressure is pressed into the aluminum melt surface by 50mm.

[0066] According to the present application, the homogenization conditions include: warming up from 50-60℃ to 470-490℃ at a rate of 50-60℃ / h, maintaining for 2-3h, then warming up to 570-590℃ at a rate of 80-100℃ / h, maintaining for 4-5h, then cooling down to 500-520℃ at a rate of 30-40℃ / h, maintaining for 3-4h, air cooling, and cooling to 20-25℃ at a cooling rate of 30-40℃ / h.

[0067] In the application, the Fe and other impurities in the mixed waste material are easy to gather, and the content of the harmful phase (such as β-AlFeSi) is relatively high, the specific three-stage temperature is used to cooperatively regulate the morphology and distribution of the impurity phase, the slow speed of 50-60℃ / h is used to rise from room temperature to 470-490℃ for low-temperature pretreatment, the temperature can promote the uniform distribution of the difficult diffusion elements Fe and Mn in the grain boundary and the grain, and release the casting residual stress, thereby laying a foundation for the element diffusion in the subsequent high-temperature stage; the medium speed of 80-100℃ / h is used to rise to 570-590℃ for entering the high-temperature strengthening stage, the conversion rate of the β phase in the mixed waste material due to the high impurity content can be more than 90%, and the diffusion of Si and Mg elements is promoted, and the composition segregation caused by the mixed waste material is eliminated; the slow speed of 30-40℃ / h is used to reduce to 500-520℃, the morphology and distribution of the α-AlFeSi phase can be stabilized in this stage, the abnormal coarsening of the α-AlFeSi phase in the cooling process is prevented, the thermal stress generated in the high-temperature stage is further released, the strength and plasticity are balanced, the progressive relationship of stress release, phase conversion and homogenization and organization stabilization is sequentially passed through the three stages, the cracking caused by stress concentration is avoided, the organization defects caused by the mixed waste material are solved, and the balance of high strength and high plasticity is realized.

[0068] According to the application, the extrusion conditions include that the extrusion die temperature is 450-470℃, the aluminum alloy casting rod heating temperature is 460-490℃, the extrusion speed is 4-7m / min, and the on-line quenching is performed at the rate of 150-300℃ / min to 20-25℃.

[0069] According to the application, the extrusion conditions include that the extrusion die temperature is 450-470℃, the aluminum alloy casting rod heating temperature is 460-490℃, the extrusion speed is 4-7m / min, and the on-line quenching is performed at the rate of 150-300℃ / min to 20-25℃.

[0070] The second aspect of the application provides an aluminum alloy prepared by the processing method of the mixed recycled aluminum waste.

[0071] The content of Si is 0.2-1.3%;

[0072] The content of Mn is ≤1.0%;

[0073] The content of Mg is 0.4-1.2%;

[0074] The content of Ti is ≤0.25%;

[0075] The content of Fe is ≤0.50%;

[0076] The content of V is 0.05-0.20%;

[0077] The content of other impurity elements is ≤0.05%.

[0078] The total content of other impurity elements is ≤0.15%;

[0079] The balance is Al.

[0080] According to the application, the water yield of the aluminum alloy is 88-91%, the hydrogen content is 0.15-0.18 mL / 100g, the yield strength is 257.9-280.5 MPa, the tensile strength is 281.7-316.1 MPa, and the elongation is 10.8-15.2%.

[0081] Test method

[0082] The chemical composition test sample is sampled by a sampler, the sample size is φ60mm*8mm, the test process and test method are in accordance with GB / T 7999-2015 "Aluminum and Aluminum Alloy Photometric System Emission Spectrometric Analysis Method", 3 repeated detections are carried out, and the average value is taken.

[0083] The water yield reflects the recovery rate of effective metal in the remelted aluminum smelting process, and embodies the removal effect of gas and volatile impurities. The total mass m 总 of raw materials input into the smelting furnace is recorded (accurate to 0.01 kg), after smelting is completed, the ingot and recyclable aluminum liquid are collected, and the total mass m 产 of output aluminum melt is weighed (accurate to 0.01 kg).

[0084] The water yield calculation formula is: water yield=m 总 / m 产 *100%.

[0085] The hydrogen content of aluminum liquid is measured by the reduced pressure solidification method. A sampler is used to extract the melt at the depth of 1 / 2-2 / 3 of the aluminum liquid in the smelting furnace, inject the melt into a standard sample tube, quickly seal both ends of the sample tube to ensure no gas leakage. The sample tube is placed into a reduced pressure solidification device, and the procedure is operated according to the provisions of GB / T24487-2009 "Determination of Hydrogen Content in Aluminum and Aluminum Alloy Melt by Reduced Pressure Solidification Method", the reduced pressure temperature is set to 715-725℃, the reduced pressure time is 10-15min, and the hydrogen content data is automatically calculated and output by the device. Each group of tests is repeated 3 times, the average value is taken, the hydrogen content result is in units of mL / 100g, and 3 decimal places are retained.

[0086] The ingot microstructure sample position is shown in the description Figure 1 , wherein D is 80mm. The processed sample is observed under a ZEISS AXIO metallographic microscope, and the test process is carried out according to GB / T3246.1-2024 "Deformed Aluminum and Aluminum Alloy Product Organization Test Method Part 1: Microstructure Test Method".

[0087] The static tensile sample size is shown in the descriptionFigure 2 The processed tensile sample was tested on an AG-X 100kN electronic universal testing machine, and the test process was carried out according to GB / T 228.1-2021 <Metallic materials-Tensile testing-Part 1: Method of test at room temperature>. The extensometer gauge length was 50mm, and the test was strain rate controlled. The strain rate was 0.00025s -1 -1 in the elastic stage and the specified plastic elongation strength stage. After reaching the extensometer limit value, the extensometer was removed, and the test speed was carried out according to the displacement speed 0.0067mm·s -1 -1 until the sample was broken. Each group was tested 3 times repeatedly, and the average value was taken.

[0088] Example 1

[0089] Pre-treatment:

[0090] The raw materials were soaked in a 7wt% NaOH solution for 12min, the electrophoretic coating was mechanically ground and peeled off, the iron impurities were removed by magnetic separation, the main body material was broken, and the main body material and the functional material were compacted.

[0091] The components and their weight percentages in the main body material were as follows: Si content was 0.37%; Mg content was 0.50%; Fe content was 0.12%; individual content of other impurity elements was ≤0.05%; total content of other impurity elements was ≤0.15%; and the balance was Al.

[0092] The melting point of the main body material was ≥650℃.

[0093] The functional material was a thin-walled aluminum alloy waste material with a wall thickness of 0.20mm and a specific surface area of 4×10 -3 m 2 / g

[0094] The components and their weight percentages in the functional material were as follows: Mg content was 1.88%; Mn content was 0.80%; Cu content was 0.17%; Fe content was 0.45%; individual content of other impurity elements was ≤0.05%; total content of other impurity elements was ≤0.15%; and the balance was Al.

[0095] The raw aluminum ingot had a purity of 99.70%.

[0096] The balance material included industrial silicon, pure magnesium ingot, Al-20%Mn intermediate alloy, and aluminum titanium boron wire AlTi5B1.

[0097] Melting and casting:

[0098] The raw materials and their weight percentages were as follows: main body material: functional material: dilution material: balance material = 40:30:27:3.

[0099] The furnace temperature is 750℃, the main body material is firstly put in, then the functional material, and finally the dilution material and the balance material, the main body material is put in four times, the weight ratio of the four times is 2:1:1:1, and the main body material is stirred 1-2 times during each time of putting in.

[0100] When the radius of the main body material is ≥30mm, the hydraulic pressure is pressed into the aluminum melt liquid surface by 100mm, and is kept for 60s, when the radius of the main body material is <30mm, the hydraulic pressure is pressed into the aluminum melt liquid surface by 50mm, and is kept for 30s.

[0101] When the radius of the functional material is ≥30mm, the hydraulic pressure is pressed into the aluminum melt liquid surface by 100mm, and is kept for 60s, when the radius of the functional material is <30mm, the hydraulic pressure is pressed into the aluminum melt liquid surface by 50mm, and is kept for 30s.

[0102] The argon gas with a purity of 99.9% and the granular refining agent are used for degassing refining, the melt temperature is 740℃, the argon gas flow is 13L / min, the refining agent is used in an amount of 2.5kg / ton of aluminum, the surface dross is removed by a mechanical dross removal method, and the unit standing time is 1.2m 3 / h.

[0103] The graphite rotor degassing machine is used for filtration, the degassing efficiency is ≥50%, the double-stage filtration device is used, the foam ceramic filter plate is used, and the 30ppi+50ppi is used.

[0104] The ingot diameter is 80mm, and the casting speed is 160mm / min.

[0105] Homogenization treatment:

[0106] The temperature is increased from 25℃ to 480℃ at a rate of 55℃ / h, is kept for 2.5h, is increased to 580℃ at a rate of 90℃ / h, is kept for 4.5h, is decreased to 510℃ at a rate of 35℃ / h, is kept for 3.5h, is air-cooled, and is cooled to 25℃ at a cooling rate of 35℃ / min, so that the homogenized aluminum alloy cast bar is obtained.

[0107] Extrusion:

[0108] The extrusion die temperature is 460℃, the aluminum alloy cast bar heating temperature is 475℃, the extrusion speed is 5m / min, and the online quenching is performed at a rate of 200℃ / min to 25℃.

[0109] Artificial aging:

[0110] The temperature is 175℃, and the temperature is kept for 8h.

[0111] The aluminum alloy A1 is prepared.

[0112] The components and their weight percentages in the aluminum alloy A1 are: Si: 1.00%, Mn: 0.60%, Mg: 0.93%, Ti: 0.02%, Fe: 0.20%, total content of other impurity elements ≤0.05%; total content of other impurity elements ≤0.15%; and the balance is Al.

[0113] Example 2

[0114] The aluminum alloy is prepared according to the processing method of Example 1, except that the raw materials and their weight percentages are: main material: functional material: dilution material: balance material = 50:20:27:3.

[0115] The aluminum alloy A2 is prepared.

[0116] The components and their weight percentages in the aluminum alloy A2 are: Si: 1.00%, Mn: 0.60%, Mg: 0.93%, Ti: 0.02%, Fe: 0.17%, total content of other impurity elements ≤0.05%; total content of other impurity elements ≤0.15%; and the balance is Al.

[0117] Example 3

[0118] The aluminum alloy is prepared according to the processing method of Example 1, except that the raw materials and their weight percentages are: main material: functional material: dilution material: balance material = 50:30:17:3.

[0119] The aluminum alloy A3 is prepared.

[0120] The components and their weight percentages in the aluminum alloy A3 are: Si: 1.00%, Mn: 0.60%, Mg: 0.93%, Ti: 0.02%, Fe: 0.21%, total content of other impurity elements ≤0.05%; total content of other impurity elements ≤0.15%; and the balance is Al.

[0121] Example 4

[0122] The aluminum alloy is prepared according to the processing method of Example 1, except that the raw materials and their weight percentages are: main material: functional material: dilution material: balance material = 60:10:26:4.

[0123] The aluminum alloy A4 is prepared.

[0124] The components and their weight percentages in the aluminum alloy A4 are: Si: 1.00%, Mn: 0.60%, Mg: 0.93%, Ti: 0.02%, Fe: 0.13%, total content of other impurity elements ≤0.05%; total content of other impurity elements ≤0.15%; and the balance is Al.

[0125] Example 5

[0126] The aluminum alloy was prepared according to the processing method of Example 1, except that the raw materials and their weight percentages were as follows: main material: functional material: dilution material: balance material = 60:20:17:3.

[0127] The aluminum alloy A5 was prepared.

[0128] The components and their weight percentages in the aluminum alloy A5 were as follows: Si: 1.00%, Mn: 0.60%, Mg: 0.93%, Ti: 0.02%, Fe: 0.18%, and the total content of other impurity elements ≤ 0.05%; the total content of other impurity elements ≤ 0.15%; and the balance was Al.

[0129] Example 6

[0130] The aluminum alloy was prepared according to the processing method of Example 1, except that the raw materials and their weight percentages were as follows: main material: functional material: dilution material: balance material = 60:20:18:2. The balance material included industrial silicon, Al-20% Mn intermediate alloy, Al-20% Cr intermediate alloy, Al-60% Cu intermediate alloy, and aluminum titanium boron wire AlTi5B1.

[0131] The aluminum alloy A6 was prepared.

[0132] The components and their weight percentages in the aluminum alloy A6 were as follows: Si: 0.73%, Cu: 0.13%, Mn: 0.25%, Mg: 0.58%, Cr: 0.15%, Fe: 0.16%, and the total content of other impurity elements ≤ 0.05%; the total content of other impurity elements ≤ 0.15%; and the balance was Al.

[0133] Example 7

[0134] The aluminum alloy was prepared according to the processing method of Example 1, except that the raw materials and their weight percentages were as follows: main material: functional material: dilution material: balance material = 60:20:16:4, and the balance material was industrial silicon, pure magnesium ingot, Al-60% Cu intermediate alloy, Al-5% V intermediate alloy, and aluminum titanium boron wire AlTi5B1.

[0135] The aluminum alloy A7 was prepared.

[0136] The components and their weight percentages in the aluminum alloy A7 were as follows: Si: 0.68%, Cu: 0.13%, Mn: 0.08%, Mg: 0.55%, V: 0.06%, Fe: 0.16%, and the total content of other impurity elements ≤ 0.05%; the total content of other impurity elements ≤ 0.15%; and the balance was Al.

[0137] Example 8

[0138] The aluminum alloy was prepared according to the processing method of Example 2, except that the temperature was raised from 20℃ to 470℃ at a rate of 50℃ / h, held for 2h, then raised to 570℃ at a rate of 80℃ / h, held for 4h, then lowered to 500℃ at a rate of 30℃ / h, held for 3h, air-cooled, and cooled to 20℃ at a rate of 30℃ / h to obtain the homogenized aluminum alloy cast rod.

[0139] The aluminum alloy A8 was prepared.

[0140] The aluminum alloy A8 contains the following components and their weight percentages: Si: 1.00%, Mn: 0.60%, Mg: 0.93%, Ti: 0.02%, Fe: 0.17%, and total content of other impurities ≤0.05%; total content of other impurities ≤0.15%; and the balance being Al.

[0141] Example 9 (right boundary value in claim 6)

[0142] The aluminum alloy was prepared according to the processing method of Example 2, except that the temperature was raised from 30℃ to 490℃ at a rate of 60℃ / h, held for 3h, then raised to 590℃ at a rate of 100℃ / h, held for 5h, then lowered to 520℃ at a rate of 40℃ / h, held for 4h, air-cooled, and cooled to 25℃ at a rate of 40℃ / h to obtain the homogenized aluminum alloy cast rod.

[0143] The aluminum alloy A9 was prepared.

[0144] The aluminum alloy A9 contains the following components and their weight percentages: Si: 1.00%, Mn: 0.60%, Mg: 0.93%, Ti: 0.02%, Fe: 0.17%, and total content of other impurities ≤0.05%; total content of other impurities ≤0.15%; and the balance being Al.

[0145] Comparative Example 1

[0146] The aluminum alloy was prepared according to the processing method of Example 1, except that the raw materials and their weight percentages were as follows: main material: functional material: dilution material: balance material = 40:40:17:3. The balance material included industrial silicon, Al-20% Mn intermediate alloy, and aluminum titanium boron wire AlTi5B1.

[0147] The aluminum alloy DA1 was prepared.

[0148] The aluminum alloy DA1 contains the following components and their weight percentages: Si: 1.00%, Mn: 0.60%, Mg: 0.93%, Ti: 0.02%, Fe: 0.25%, and total content of other impurities ≤0.05%; total content of other impurities ≤0.15%; and the balance being Al.

[0149] Comparative Example 2

[0150] An aluminum alloy was prepared according to the processing method of Example 1, except that the raw materials and their weight percentages were as follows: main material: functional material: dilution material: balance material = 60:30:7:3.

[0151] An aluminum alloy DA2 was prepared.

[0152] The components and their weight percentages in the aluminum alloy DA2 were as follows: Si: 1.00%, Mn: 0.60%, Mg: 0.93%, Ti: 0.02%, Fe: 0.20%, and the total content of other impurity elements ≤0.05%; the total content of other impurity elements ≤0.15%; and the balance was Al.

[0153] Comparative Example 3

[0154] An aluminum alloy was prepared according to the processing method of Example 2, except that in the melting and casting process, the main material and the functional material were not subjected to hydraulic pressure.

[0155] An aluminum alloy DA3 was prepared.

[0156] Comparative Example 4

[0157] An aluminum alloy was prepared according to the processing method of Example 2, except that the homogenization system of the casting rod was 560℃×10h.

[0158] An aluminum alloy DA4 was prepared.

[0159] Comparative Example 5

[0160] An aluminum alloy was prepared according to the processing method of Example 2, except that the temperature was raised from 40℃ to 460℃ at a rate of 40℃ / h for 1h, then raised to 560℃ at a rate of 70℃ / h for 3h, then lowered to 490℃ at a rate of 20℃ / h for 2h, air-cooled, and cooled to 15℃ at a cooling rate of 20℃ / min to obtain the homogenized aluminum alloy casting rod.

[0161] An aluminum alloy DA5 was prepared.

[0162] Comparative Example 6

[0163] An aluminum alloy was prepared according to the processing method of Example 2, except that the temperature was raised from 70℃ to 500℃ at a rate of 70℃ / h for 4h, then raised to 600℃ at a rate of 110℃ / h for 6h, then lowered to 530℃ at a rate of 50℃ / h for 5h, air-cooled, and cooled to 30℃ at a cooling rate of 50℃ / min to obtain the homogenized aluminum alloy casting rod.

[0164] An aluminum alloy DA6 was prepared.

[0165] Performance tests were conducted on A1-A9 and DA1-DA6, as shown in Table 1.

[0166] Table 1

[0167]

[0168] The water yield reflects the removal effect of gas and volatile impurities in the molten aluminum, and the higher the value is, the better it is. The industry quality standard is ≥ 85%. The hydrogen content refers to the amount of hydrogen dissolved in the molten aluminum, and the industry qualified standard is ≤ 0.20 mL / 100g.

[0169] Through the comparison of examples and comparative examples, it can be seen that the water yield and hydrogen content results of all examples meet the industry standards, and comparative example 2, comparative example 4 and comparative example 5 do not meet the standards.

[0170] In comparative example 2, the functional material is excessive, and the water yield and hydrogen content results are unqualified. The functional material has a thin wall structure, and the specific surface area is 2-3 times that of the main material. When the proportion of the functional material increases from 30% to 40%, the specific surface area of the waste material increases, and it is difficult to completely immerse the excessive functional material even if the down pressure operation is adopted. The exposure time of the waste material is prolonged, and the water yield is reduced (80%). In addition, the content of elements such as Mn and Mg in the functional material is higher than that in the main material. When the functional material is excessive, it is easier to form complex intermetallic compounds, which gather at the grain boundaries and become hydrogen traps, and the hydrogen adsorption amount increases to 0.21 mL / 100g.

[0171] In comparative example 4, the total proportion of the main material and the functional material exceeds the range, and the water yield and hydrogen content results are unqualified. The proportion of the dilution material is only less than 10%, and the role of the purification buffer is weakened. The gas impurities in the recycled aluminum melt increase, the water yield decreases to 83%, and the hydrogen adsorption amount increases to 0.21 mL / 100g.

[0172] In comparative example 5, the hydraulic down pressure device is not enabled during the smelting process, and the water yield and hydrogen content results are unqualified. When there is no down pressure, most of the waste material will be directly in contact with air, and the oxidation loss is serious, and the hydrogen absorption is more serious. The moisture (H2O) in the air reacts with aluminum to generate hydrogen through the cracks in the oxidation film, and the formula is 2Al + 3H2O → Al2O3+ 3H2. The water yield and hydrogen content of comparative example 5 are only 75% and 0.25 mL / 100g, respectively. All examples use hydraulic down pressure, and the average water yield increases to 89% and the average hydrogen content decreases to 0.16 mL / 100g. When the waste material is put in, the hydraulic down pressure is used at the same time, which can completely immerse the waste material in the melt and reduce the exposure time of the waste material. However, if the total amount of the waste material is excessive or the functional material is excessive, the reduction of the waste material loss by using the hydraulic down pressure cannot make up for the defects caused by the excessive waste material, for example, comparative example 4.

[0173] The average size of the second phase in the example, measured by the equivalent circle diameter method, was approximately 7.8 μm. In contrast, Comparative Example 6, with the same waste ratio as Example 2 and using a traditional single-stage homogenization process, achieved an average second phase size of 15.0 μm, indicating that the traditional single-stage homogenization process is insufficient for optimizing the second phase in recycled aluminum. The example employs a specific three-stage homogenization process of this invention. The 470-490℃ low-temperature stage allows for increased diffusion space for difficult-to-diffuse elements at high temperatures, and this stage also releases some residual stress caused by uneven casting cooling. The 570-590℃ stage is a high-temperature strengthening stage, where the second phase dissolves and rearranges. A slow cooling rate of 30-40℃ / h leads to 500-520℃, entering a mid-temperature stabilization stage. This slow cooling deeply eliminates residual stress, preventing cracking during subsequent processing. The mid-temperature stage also reduces dislocation density in the high-temperature stage, improving plasticity.

[0174] Instruction manual attached Figure 3 Included with instruction manual Figure 4 The images show the microstructure of the cast rods after homogenization in Example 2 and Comparative Example 6, respectively. Figure 3 It can be seen that in Example 2, the grain boundaries are relatively narrow, with no obvious thickening. The second phase is fine and dispersed, mostly in the form of short strips or small particles, and is relatively uniformly distributed in the matrix, without obvious agglomeration, continuous network, or other undesirable distribution morphologies. After three-stage homogenization, the β-harmful phase is fully transformed, resulting in a rounded morphology and uniform distribution. Figure 4 It can be seen that the second phase in Comparative Example 6 is significantly larger in size and more complex in morphology, with more continuous, coarse network-like or irregular blocky second phases, poor distribution uniformity, and obvious local agglomeration. Single-stage homogenization failed to effectively regulate the Fe phase transformation, resulting in numerous microstructural defects and deteriorated performance.

[0175] Examples 1-5 have a yield strength ≥265MPa, tensile strength ≥305MPa, and elongation >10%. Examples 6-7 have a yield strength ≥250MPa, tensile strength ≥270MPa, and elongation >12%. Comparative Example 2 had an excessive amount of functional material, and Comparative Example 4 had an excessive amount of waste material. Both alloys introduced more impurity elements, and complex Fe-containing intermetallic compounds were easily present in the microstructure, reducing mechanical properties. Even with hydraulic pressing combined with specific three-stage homogenization, this loss could not be compensated for. Comparative Example 5 did not have hydraulic pressing; compared to Example 2, it showed severe burn-off and a significant decrease in mechanical properties. Comparative Example 6 used traditional single-stage homogenization; compared to Example 2, the microstructure optimization effect was poor, and mechanical properties were significantly reduced.

[0176] Through performance verification, the weight percentage of the functional material is 10-30%, the sum of the weight percentages of the main material and the functional material is 70-80%, a specific hydraulic pressure is adopted, and a specific three-stage homogenization system is adopted, so that an aluminum alloy with a yield strength of greater than or equal to 265 MPa, a tensile strength of greater than or equal to 305 MPa, and an elongation of greater than or equal to 10% can be prepared, and the raw material cost is reduced by at least 3%.

[0177] The above merely describes preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical scheme and inventive concept of the present application, should be covered within the protection scope of the present application.

Claims

1. A process for the treatment of mixed secondary aluminium scrap, characterized in that, The processing method comprises: waste pre-treatment, melting and casting, homogenization, extrusion, artificial aging; The raw materials of the mixed recycled aluminum waste and the weight percentage thereof are: 40-60% of main material, 10-30% of functional material, 15-28% of dilution material, and 2-5% of balance material, wherein the sum of the weight percentage of the main material and the functional material is 70-80%, and the sum of the weight percentage of the dilution material and the balance material is 20-30%; The components in the main material and the weight percentage thereof are: Si content of 0.20-0.70%; Mg content of 0.45-0.70%; Fe content of 0.10-0.25%; single content of other impurity elements ≤0.05%; total content of other impurity elements ≤0.15%; and the balance is Al; The melting point of the main material is ≥650℃; said functional material being thin-walled aluminium alloy scrap having a wall thickness of 0.10-0.30 mm, a specific surface area of 3 x 10 -3 -5 x 10 -3 m 2 / g; The components in the functional material and the weight percentage thereof are: Mg content of 1.65-2.45%; Mn content of 0.50-1.00%; Cu content of 0.03-0.17%; Fe content of 0.30-0.60%; single content of other impurity elements ≤0.05%; total content of other impurity elements ≤0.15%; and the balance is Al; The dilution material is original aluminum ingot with purity ≥99.70%; The balance material includes at least one of industrial silicon, pure magnesium ingot, Al-20%Mn intermediate alloy, Al-20%Cr intermediate alloy, Al-60%Cu intermediate alloy, Al-5%V intermediate alloy, and aluminum titanium boron wire AlTi5B1.

2. The treatment method according to claim 1, characterized in that, The waste pre-treatment comprises: soaking the raw materials in a 5-8wt% NaOH solution for 10-15min, mechanically grinding and stripping the electrophoretic coating, magnetically removing iron impurities, crushing the main material, and compacting the main material and the functional material.

3. The treatment method of claim 1, wherein The melting and casting comprises: furnace temperature of 740-760℃, feeding raw materials, refining, slagging, degassing, filtering, and casting; The sequence of feeding raw materials is: feeding the main material first, then feeding the functional material, and finally feeding the dilution material and the balance material; The main material is fed in 4-8 times, and the mass ratio of the first time to the remaining times is 2:1-2; In the process of feeding the main material each time, stirring is performed 1-2 times. After feeding the main material, when the melt temperature is 670-700℃, the functional material is fed, and the fed functional material is hydraulically pressed into the aluminum melt liquid surface 50-100mm below, and kept for 30-60s; 4. The treatment method according to claim 3, characterized in that, In the process of feeding the functional material, stirring is performed 1-2 times; When the radius of the main material is ≥30mm, the hydraulic pressing is performed 100mm below the aluminum melt liquid surface, and when the radius of the main material is <30mm, the hydraulic pressing is performed 50mm below the aluminum melt liquid surface; When the radius of the functional material is ≥30mm, the hydraulic pressing is performed 100mm below the aluminum melt liquid surface, and when the radius of the functional material is <30mm, the hydraulic pressing is performed 50mm below the aluminum melt liquid surface. ​ 5. The treatment method of claim 1, wherein The homogenizing conditions include: warming from 20-30 DEG C to 470-490 DEG C at a rate of 50-60 DEG C / h, holding for 2-3 h, then warming to 570-590 DEG C at a rate of 80-100 DEG C / h, holding for 4-5 h, then cooling to 500-520 DEG C at a rate of 30-40 DEG C / h, holding for 3-4 h, air cooling, and cooling to 20-25 DEG C at a rate of 30-40 DEG C / h.

6. The treatment method of claim 1, wherein The extruding conditions include: an extruding die temperature of 450-470 DEG C, an aluminum alloy cast bar heating temperature of 460-490 DEG C, an extruding speed of 4-7 m / min, and online quenching at a rate of 150-300 DEG C / min to 20-25 DEG C.

7. The treatment method of claim 1, wherein The artificial aging conditions include: a temperature of 70-210 DEG C, and holding for 4-10 h.

8. The aluminium alloy produced according to the process for treating mixed recycled aluminium scrap according to any one of claims 1 to 7, characterised in that, The aluminum alloy contains the following components and their weight percentages: Si content is 0.2-1.3%; Mn content is ≤1.0%; Mg content is 0.4-1.2%; Ti content is ≤0.25%; Fe content is ≤0.50%; V content is 0.05-0.20%; other impurity elements each ≤0.05%; total content of other impurity elements is ≤0.15%; the balance is Al.

9. The aluminum alloy of claim 8, wherein, The aluminum alloy has a water discharge rate of 88-91%, a hydrogen content of 0.15-0.18 mL / 100 g, a yield strength of 257.9-280.5 MPa, a tensile strength of 281.7-316.1 MPa, and an elongation of 10.8-15.2%.

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