A 6-series recycled aluminum alloy with impact energy absorption and intergranular corrosion resistance and a preparation method thereof

Abstract

The application belongs to the technical field of alloy materials, and particularly relates to a 6-series recycled aluminum alloy with impact absorption and intergranular corrosion resistance and a preparation method thereof. The 6-series recycled aluminum alloy with impact absorption and intergranular corrosion resistance is composed of the following components in percentage by weight: Mg 0.45-0.60%, Si 0.40-0.50%, Fe≤0.25%, Cu≤0.50%, Mn≤0.10%, Cr≤0.10%, Ti≤0.10%, V≤0.20%, Zn≤0.10%, other inevitable impurity elements: single≤0.05%, total≤0.15%, and the rest is Al, the aluminum element is derived from 15-25% of raw aluminum and 75-85% of recycled aluminum, and the 6-series recycled aluminum alloy with impact absorption and intergranular corrosion resistance with good mechanical properties is obtained at a lower cost under the condition of adding a higher content of recycled aluminum.

Description

Technical Field

[0001] This invention belongs to the field of alloy materials technology, specifically relating to a 6-series recycled aluminum alloy that is impact-resistant, energy-absorbing, and resistant to intergranular corrosion, and its preparation method. Background Technology

[0002] In recent years, energy conservation has been a major concern, with the recycling of scrap metal resources being a key focus for my country's non-ferrous metals industry to achieve carbon peaking and carbon neutrality. Data shows that recycling aluminum can reduce ore mining, save electricity, and decrease emissions of carbon dioxide (CO2) and sulfur dioxide (SO2). More and more automakers are focusing on building green supply chain projects for recycled aluminum; for example, BMW announced that it will use 30% recycled aluminum in its 2021 aluminum production.

[0003] The application of recycled aluminum is currently mainly in building and industrial materials, where the overall performance requirements are relatively low, and it is used to a limited extent in automotive structural parts. The main problems are: ① The composition of recycled aluminum is difficult to control, the addition ratio is low, the types of aluminum alloys are diverse, the recycling sources are unstable, and the final composition is difficult to control, making it difficult to apply in automotive materials with strict composition requirements; ② Recycled aluminum has many defects in its matrix structure, which are difficult to improve, resulting in poor mechanical properties. For example, controlling the iron-rich phase in recycled aluminum mainly involves adding elements such as Mn and Cr to modify the inclusion phases, which limits the use of alloys that do not contain these additive elements. While adding large amounts of recycled aluminum to aluminum alloy systems can reduce production costs, it also carries the risk of sacrificing mechanical properties. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned technical problems by providing a 6-series recycled aluminum alloy that is impact-resistant, energy-absorbing, and resistant to intergranular corrosion, which can maintain good mechanical properties and resistance to intergranular corrosion even with the addition of a large amount of recycled aluminum.

[0005] The impact-resistant, energy-absorbing, and intergranular corrosion-resistant 6-series recycled aluminum alloy of the present invention is composed of the following components by weight percentage: Mg 0.45-0.60%, Si 0.40-0.50%, Fe≤0.25%, Cu≤0.50%, Mn≤0.10%, Cr≤0.10%, Ti≤0.10%, V≤0.20%, Zn≤0.10%, other unavoidable impurity elements: individual ≤0.05%, total ≤0.15%, the remainder being Al.

[0006] Furthermore, in the aforementioned 6-series recycled aluminum alloys that are impact-resistant, energy-absorbing, and resistant to intergranular corrosion, the Mg+Si content is 0.9-1.1%. When the magnesium and silicon content is too high, the material's plasticity decreases significantly, and its strength is too high, which is not conducive to extrusion.

[0007] Furthermore, the Mg / Si mass ratio in the aforementioned impact-resistant, energy-absorbing, and intergranular corrosion-resistant 6-series recycled aluminum alloy is 1.0-1.4. This required magnesium-to-silicon mass ratio ensures that silicon and sufficient magnesium form a reinforcing phase, while also preventing excessive magnesium and silicon from impairing the material's strength and toughness.

[0008] Furthermore, the aluminum in the aforementioned impact-resistant, energy-absorbing, and intergranular corrosion-resistant 6-series recycled aluminum alloys comes from 15-25% primary aluminum and 75-85% recycled aluminum.

[0009] Furthermore, the aforementioned 6-series recycled aluminum alloy, which is impact-resistant, energy-absorbing, and resistant to intergranular corrosion, has a recrystallized microstructure.

[0010] The present invention also provides a method for preparing the above-mentioned impact-resistant, energy-absorbing, and intergranular corrosion-resistant 6-series recycled aluminum alloy, including batching, smelting, casting, homogenization treatment, extrusion, and aging treatment.

[0011] Furthermore, the melting temperature is 700-750℃.

[0012] Furthermore, the smelting process involves two refining processes at a temperature of 730-750℃.

[0013] Furthermore, the casting temperature is 680-700℃, and the casting speed is 100-130mm / min.

[0014] Furthermore, during casting, online argon gas slag and gas removal and two-stage plate filtration with 30-40 / 50-60 mesh are used. The combination of online argon gas slag and gas removal and two-stage plate filtration—coarse first and then fine—can more effectively remove fine metallic and non-metallic inclusions in the molten aluminum, which is particularly important for subsequent mechanical and corrosion resistance.

[0015] Furthermore, a two-stage homogenization process is employed: first, the temperature is held at 500-540℃ for 3-6 hours, and then at 550-580℃ for 5-8 hours. This two-stage homogenization process prevents significant overheating caused by the Al / Si / Mg2Si reaction in the matrix when the temperature is raised to 550-580℃, improves the internal structure of the alloy, and contributes to obtaining good mechanical properties and corrosion resistance.

[0016] Furthermore, the aluminum rod temperature during extrusion is 480-520℃, and the quenching temperature is ≥520℃.

[0017] Furthermore, after extrusion, the material is quenched and cooled by strong water spray.

[0018] Furthermore, the aging treatment temperature is 200-220℃, and the time is 4-10 hours.

[0019] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0020] (1) By adding a higher content of recycled aluminum, a 6-series recycled aluminum alloy with good mechanical properties, impact energy absorption and resistance to intergranular corrosion can be obtained at a lower cost.

[0021] (2) With a suitable mass ratio of magnesium and silicon, the silicon and sufficient magnesium elements are used to form a reinforcing phase, and excess magnesium and silicon are prevented from damaging the strength and toughness of the material.

[0022] (3) The yield strength of the 6-series recycled aluminum alloy obtained by this invention can reach 180-240MPa, and it also has good impact resistance.

[0023] (4) Using two-stage filtration and two-stage homogenization can reduce the inclusion phase in the matrix, while reducing the segregation and overheating of the structure, improving the grain boundary and intragranular structure, which helps to obtain good mechanical properties and resistance to intergranular corrosion. Attached Figure Description

[0024] Figure 1 Here is a SEM image of the microstructure of the cast rod in Example 1;

[0025] Figure 2 The image shows the impact-resistant, energy-absorbing, and intergranular corrosion-resistant crushed 6-series recycled aluminum alloy obtained in Example 1.

[0026] Figure 3 The images show the impact-resistant, energy-absorbing, and intergranular corrosion-resistant 6-series recycled aluminum alloy obtained in Example 1.

[0027] Figure 4 Here is a SEM image of the microstructure of the cast rod in Example 4;

[0028] Figure 5 The image shows a crushed photograph of the 6-series recycled aluminum alloy obtained in Example 4;

[0029] Figure 6 Corrosion photographs of the 6-series recycled aluminum alloy obtained in Example 4;

[0030] Figure 7 Here is a SEM image of the microstructure of the cast rod in Example 5;

[0031] Figure 8 The image shows a crushed photograph of the 6-series recycled aluminum alloy obtained in Example 5.

[0032] Figure 9 The image shows a corrosion photograph of the 6-series recycled aluminum alloy obtained in Example 5. Detailed Implementation

[0033] The technical solution of the present invention will be further described and illustrated below with reference to specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of helping to understand the present invention and are not intended to limit the specific scope of the present invention. Furthermore, the accompanying drawings used herein are merely for better illustrating the content disclosed in the present invention and do not limit the scope of protection. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used in the art, and the methods used in the embodiments are all conventional methods in the art.

[0034] Example 1

[0035] The method for preparing the 6-series recycled aluminum alloy with impact resistance, energy absorption, and intergranular corrosion resistance in this embodiment includes the following steps:

[0036] (1) The ingredients are prepared according to the following proportions: Mg 0.45%, Si 0.45%, Fe 0.25%, Cu 0.01%, Mn 0.05%, Cr 0.03%, Ti 0.03%, V 0.03%, Zn 0.05%, and Al 98.65% (20% primary aluminum and 80% recycled aluminum). The Mg+Si ratio is 0.9%, and the Mg / Si mass ratio is 1.0.

[0037] (2) After melting at 730℃, two refining processes are carried out at a refining temperature of 750℃. Casting is carried out at 690℃, with argon gas used for online slag removal and degassing, and 40 / 60 mesh double-stage plate filtration. The casting speed is 120mm / min.

[0038] (3) First, keep it at 500℃ for 6 hours, then keep it at 550℃ for 8 hours for homogenization treatment, and obtain the casting rod after spray cooling.

[0039] (4) Heat the rod to 500℃ and extrude it. After quenching at 530℃, cool it by strong water spray.

[0040] (5) Aging treatment was carried out at 200℃ for 8 hours to obtain 6-series recycled aluminum alloy.

[0041] Example 2

[0042] The method for preparing the 6-series recycled aluminum alloy with impact resistance, energy absorption, and intergranular corrosion resistance in this embodiment includes the following steps:

[0043] (1) The raw materials were prepared according to the following proportions: Mg 0.57%, Si 0.43%, Fe 0.25%, Cu 0.03%, Mn 0.05%, Cr 0.03%, Ti 0.03%, V 0.03%, Zn 0.05%, and Al 98.53% (20% primary aluminum and 80% recycled aluminum). The Mg+Si ratio was 1.0%, and the Mg / Si mass ratio was 1.3.

[0044] (2) After melting at 720℃, two refining processes are carried out at a refining temperature of 740℃. Casting is carried out at 680℃, and argon gas is used for online slag removal and degassing, and 40 / 60 mesh double-stage plate filtration is used. The casting speed is 110mm / min.

[0045] (3) First, keep it at 520℃ for 6 hours, then keep it at 560℃ for 8 hours for homogenization treatment, and then obtain the casting rod after spray cooling.

[0046] (4) Heat the rod to 500℃ and extrude it. After quenching at 530℃, cool it by strong water spray.

[0047] (5) Aging treatment was carried out at 210℃ for 6 hours to obtain 6-series recycled aluminum alloy.

[0048] Example 3

[0049] The method for preparing the 6-series recycled aluminum alloy with impact resistance, energy absorption, and intergranular corrosion resistance in this embodiment includes the following steps:

[0050] (1) The raw materials were prepared according to the following composition: Mg 0.64%, Si 0.46%, Fe 0.25%, Cu 0.05%, Mn 0.05%, Cr 0.03%, Ti 0.03%, V 0.03%, Zn 0.05%, and Al 98.41% (20% primary aluminum and 80% recycled aluminum). The Mg+Si ratio was 1.1%, and the Mg / Si mass ratio was 1.4.

[0051] (2) After melting at 730℃, two refining processes are carried out at a refining temperature of 750℃. Casting is performed at 690℃, using argon gas for online slag removal and degassing, and 40 / 60 mesh double-stage plate filtration. The casting speed is 125mm / min.

[0052] (3) First, keep it at 500℃ for 6 hours, then keep it at 550℃ for 8 hours for homogenization treatment, and obtain the casting rod after spray cooling.

[0053] (4) Heat the rod to 510℃ and extrude it. After quenching at 540℃, cool it by strong water spray.

[0054] (5) Aging treatment was carried out at 210℃ for 6 hours to obtain 6-series recycled aluminum alloy.

[0055] Example 4

[0056] The only difference between this embodiment and embodiment 1 is that in step (3), the rod is homogenized by holding it at 550°C for 14 hours and then cooled by spraying.

[0057] Example 5

[0058] The only difference between this embodiment and implementation 1 is that in step (2), after melting at 730°C, two refining processes are performed, with a refining temperature of 750°C. Casting is carried out at 690°C, using argon gas for online slag removal and degassing, and a 30-mesh plate filter. The casting speed is 120 mm / min.

[0059] Comparative Example 1

[0060] The only difference between this comparative example and Example 1 is that in step (1), the ingredients are prepared according to the following proportions: Mg 0.45%, Si 0.45%, Fe 0.25%, Cu 0.01%, Mn 0.05%, Cr 0.03%, Ti 0.03%, V 0.03%, Zn 0.05%, and Al 98.65% (10% primary aluminum and 90% recycled aluminum).

[0061] Comparative Example 2

[0062] The only difference between this comparative example and Example 1 is that in step (1), the ingredients are prepared according to the following proportions: Mg 0.45%, Si 0.45%, Fe 0.25%, Cu 0.01%, Mn 0.05%, Cr 0.03%, Ti 0.03%, V 0.03%, Zn 0.05%, and Al 98.65% (30% primary aluminum and 70% recycled aluminum).

[0063] Comparative Example 3

[0064] The only difference between this comparative example and Example 1 is that in step (1), the ingredients are prepared according to the following proportions: Mg 0.40%, Si 0.40%, Fe 0.25%, Cu 0.01%, Mn 0.05%, Cr 0.03%, Ti 0.03%, V 0.03%, Zn 0.05%, and Al 98.75% (20% primary aluminum and 80% recycled aluminum), with Mg+Si = 0.8% and the Mg / Si mass ratio being 1.0.

[0065] Comparative Example 4

[0066] The only difference between this comparative example and Example 1 is that in step (1), the ingredients are prepared according to the following proportions: Mg 0.60%, Si 0.60%, Fe 0.25%, Cu 0.01%, Mn 0.05%, Cr 0.03%, Ti 0.03%, V 0.03%, Zn 0.05%, and Al 98.35% (20% primary aluminum and 80% recycled aluminum), with Mg+Si = 1.2% and the Mg / Si mass ratio being 1.0.

[0067] Comparative Example 5

[0068] The only difference between this comparative example and Example 1 is that in step (1), the ingredients are prepared according to the following proportions: Mg 0.40%, Si 0.50%, Fe 0.25%, Cu 0.01%, Mn 0.05%, Cr 0.03%, Ti 0.03%, V 0.03%, Zn 0.05%, and Al 98.65% (20% primary aluminum and 80% recycled aluminum), with Mg+Si = 0.9% and the Mg / Si mass ratio being 0.8.

[0069] Comparative Example 6

[0070] The only difference between this comparative example and Example 1 is that in step (1), the ingredients are prepared according to the following proportions: Mg 0.55%, Si 0.35%, Fe 0.25%, Cu 0.01%, Mn 0.05%, Cr 0.03%, Ti 0.03%, V 0.03%, Zn 0.05%, and Al 98.65% (20% primary aluminum and 80% recycled aluminum), with Mg+Si = 0.9% and the Mg / Si mass ratio being 1.6.

[0071] Mechanical properties of the 6-series recycled aluminum alloys obtained in the examples and comparative examples were tested, and the test results are shown in Table 1.

[0072] Table 1. Mechanical property data of 6-series recycled aluminum alloys

[0073] Tensile strength (MPa) Yield strength (MPa) Elongation at break (%) Example 1 219 191 12.1 Example 2 231 201 11.8 Example 3 238 209 11.9 Example 4 214 185 10.4 Example 5 211 182 9.8 Comparative Example 1 206 167 10.2 Comparative Example 2 212 186 11.5 Comparative Example 3 202 164 13.4 Comparative Example 4 258 225 8.2 Comparative Example 5 216 185 9.5 Comparative Example 6 209 179 11.6

[0074] In Example 1, step (3) yielded the following microstructure of the cast rod: Figure 1 As shown, the size of the iron-containing inclusion phase can be controlled below 30 μm. Examples 1-3 yielded 6-series recycled aluminum alloys with good mechanical properties, impact energy absorption, and intergranular corrosion resistance. The crushing behavior of the 6-series recycled aluminum alloy obtained in Example 1 is shown below. Figure 2 As shown, intergranular corrosion is as follows Figure 3 As shown, in Example 4, homogenization was performed only by holding the casting at 550℃ for 14 hours, resulting in the microstructure of the cast rod as shown. Figure 4 As shown, the crushing situation is as follows Figure 5 As shown, intergranular corrosion is as follows Figure 6 As shown, in Example 5, only a 30-mesh filter plate was used during the casting process, resulting in the following microstructure of the cast rod: Figure 7 As shown, the crushing situation is as follows Figure 8 As shown, intergranular corrosion is as follows Figure 9 As shown, through Figure 1 , Figure 4 and Figure 7 The comparison shows that Figure 1 The white iron-rich phase in it is significantly more than Figure 4 and Figure 7The low concentration of recycled aluminum indicates that the casting, filtration, and homogenization processes following the addition of recycled aluminum have a significant impact on improving the distribution of the iron-rich phase. This is demonstrated by comparison. Figure 2 , Figure 5 and Figure 8 It can be seen Figure 2 Its crushing performance is better than Figure 5 and Figure 8 By comparison Figure 3 Figure 6 and Figure 9 It can be seen Figure 3 The corrosion depth is much smaller than Figure 6 and Figure 9 The results indicate that the addition of recycled aluminum in the casting filtration and two-stage homogenization processes significantly affects the toughness and corrosion resistance of the alloy. In Comparative Example 1, adding 10% primary aluminum and 90% recycled aluminum resulted in increased aluminum content, leading to a decrease in the amount of impurity elements introduced and thus a reduction in alloy performance. In Comparative Example 2, adding 30% primary aluminum and 70% recycled aluminum did not improve the mechanical properties of the resulting alloy, but increased the production cost. In Comparative Example 3, the sum of magnesium and silicon content was too low, resulting in a reduction in the reinforcing phase content and lower mechanical strength of the resulting aluminum alloy. In Comparative Example 4, the sum of magnesium and silicon content was too high, resulting in excessive mechanical strength, reduced plasticity, and difficulty in extrusion. In Comparative Example 5, the magnesium-to-silicon mass ratio was too low, leading to a decrease in the mechanical properties and poorer crushing performance of the resulting alloy. In Comparative Example 6, the magnesium-to-silicon mass ratio was too high, resulting in reduced alloy strength and significantly decreased extrusion performance.

[0075] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the spirit of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various modifications or additions to the described embodiments or use similar methods to replace them; it is neither necessary nor possible to exemplify all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the invention still fall within the scope of protection of the invention, and interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A 6-series recycled aluminum alloy that is impact-resistant, energy-absorbing, and resistant to intergranular corrosion, characterized in that, The impact-resistant, energy-absorbing, and intergranular corrosion-resistant 6-series recycled aluminum alloy is composed of the following components by weight percentage: Mg 0.45%, Si 0.45%, Fe 0.25%, Cu 0.01%, Mn 0.05%, Cr 0.03%, Ti 0.03%, V 0.03%, Zn 0.05%, and other unavoidable impurity elements: individual ≤0.05%, total ≤0.15%, with the remainder being Al; The aluminum in the 6-series recycled aluminum alloy comes from 20% primary aluminum and 80% recycled aluminum. The 6-series recycled aluminum alloy has a recrystallized microstructure, and the size of the iron-containing inclusion phase is controlled below 30 μm. The preparation method of the 6-series recycled aluminum alloy includes the following steps: (1) The ingredients are prepared according to the following proportions: Mg 0.45%, Si 0.45%, Fe 0.25%, Cu 0.01%, Mn 0.05%, Cr 0.03%, Ti 0.03%, V 0.03%, Zn 0.05%, and Al 98.65%. (2) After melting at 730℃, two refining processes are carried out at a refining temperature of 750℃. Casting is carried out at 690℃, with argon gas used for online slag removal and degassing, and 40 / 60 mesh double-stage plate filtration. The casting speed is 120 mm / min. (3) First, keep it at 500℃ for 6 hours, then keep it at 550℃ for 8 hours for homogenization treatment, and obtain the casting rod after spray cooling; (4) The rod is heated to 500℃ and extruded, then quenched at 530℃ and cooled by strong water spray. (5) Aging treatment was carried out at 200℃ for 8 hours to obtain 6-series recycled aluminum alloy.

Images