High-temperature-resistant and corrosion-resistant 6-series aluminum alloy profile for automobile chassis and preparation method

Abstract

The invention belongs to the technical field of aluminum alloy processing technologies, and particularly discloses a high-temperature-resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis and a preparation method of the high-temperature-resistant and corrosion-resistant 6-series aluminum alloy profile for the automobile chassis, and the high-temperature-resistant and corrosion-resistant 6-series aluminum alloy profile for the automobile chassis comprises the following components in percentage by weight: 0.35-0.40% of Si; the content of Fe is 0.10%-0.20%; the content of Cu is less than or equal to 0.03%; the content of Mn is 0.05%-0.10%; the content of Mg is 0.50%-0.55%; the content of Cr is less than or equal to 0.05%; the content of Zn is less than or equal to 0.05%; the content of Ti is less than or equal to 0.10%; the content of Zr is 0.03%-0.05%; the single impurity content is less than or equal to 0.05%; the total impurity content is less than or equal to 0.15%; and the balance of Al. By optimizing alloy components and adjusting a homogenization system and extrusion process parameters, the corrosion resistance of the profile for the automobile chassis in a high-temperature environment is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloy processing technology, and specifically discloses a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automobile chassis and a preparation method thereof. Background Art

[0002] With the rapid development of the global automotive industry towards lightweight, aluminum alloy materials have gradually become one of the preferred materials in the automotive manufacturing field due to their excellent properties such as light weight, corrosion resistance, and easy formability. Especially in the high-end automotive field, the application of aluminum alloy can not only significantly reduce the weight of the whole vehicle, but also effectively improve fuel efficiency, reduce carbon emissions, and enhance the handling performance and safety of the vehicle. However, with the continuous expansion of the domestic and international high-end automotive market, the performance requirements for aluminum alloy materials are also constantly increasing. Especially when exposed to harsh working conditions such as long-term exposure to sunlight and rain, automotive parts need to have stronger heat resistance and corrosion resistance, which poses new challenges to the research and development of aluminum alloy materials.

[0003] At present, the research in the field of automotive aluminum profiles in China mainly focuses on the mechanical properties and forming processes of materials, while the research on the corrosion resistance after long-term heat treatment is relatively less. Especially in the profiles for high-end automotive chassis, the deficiencies of the existing technologies are gradually emerging. For example, in the heat treatment conditions of holding at 130 °C for 1000 hours for the actually produced 6060 aluminum alloy profiles for automotive chassis, the intergranular corrosion depth generally exceeds 150 microns. Such serious corrosion phenomena will not only significantly reduce the mechanical properties of the materials, but also may cause early failure of the parts during use, thus seriously affecting the production and development and market competitiveness of high-end automotive parts.

[0004] In view of the above problems, it is of great practical significance to research and design a new type of heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automotive chassis and its preparation method. By optimizing the alloy composition and production process, the corrosion resistance of the material in high-temperature environments can be significantly improved, the service life of the parts can be extended, and the maintenance cost can be reduced. This technological breakthrough can not only meet the needs of the domestic high-end automotive market. Summary of the Invention

[0005] In order to solve the problems of serious intergranular corrosion and insufficient corrosion resistance in the existing profiles for automotive chassis under high-temperature environments, the present invention provides a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automotive chassis and a preparation method thereof.

[0006] In the first aspect of the present invention, a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automotive chassis is provided, and the components and their weight percentages in the profile for automotive chassis are as follows:

[0007] The Si content is 0.35% - 0.40%;

[0008] The Fe content is 0.10% to 0.20%;

[0009] The Cu content is ≤ 0.03%;

[0010] The Mn content is 0.05% to 0.10%;

[0011] The Mg content is 0.50% to 0.55%;

[0012] The Cr content is ≤ 0.05%;

[0013] The Zn content is ≤ 0.05%;

[0014] The Ti content is ≤ 0.10%;

[0015] The Zr content is 0.03% to 0.05%;

[0016] The content of a single impurity is ≤ 0.05%;

[0017] The total impurity content is ≤ 0.15%;

[0018] The balance is Al.

[0019] The second aspect of the present invention provides a method for preparing a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis, comprising the following steps:

[0020] S1. Batching to obtain aluminum alloy raw materials;

[0021] S2. Melting and casting: putting the prepared aluminum alloy raw materials into a melting furnace for melting and casting to obtain a casting rod;

[0022] S3. Homogenization of the casting rod: performing homogenization treatment on the casting rod to obtain a round ingot, and the homogenization system in the homogenization treatment is 565°C to 575°C × 6 h, and after taking out of the furnace, it is cooled to room temperature by water mist;

[0023] S4. Extrusion: putting the round ingot into an extrusion device for extrusion molding to obtain an aluminum alloy profile;

[0024] S5. Quenching: performing quenching treatment on the aluminum alloy profile;

[0025] S6. Aging treatment: performing aging treatment on the quenched aluminum alloy profile to obtain a profile for an automobile chassis.

[0026] According to a method for preparing a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to some embodiments of the present application, in the step S2, the melting temperature during melting and casting is 700°C to 720°C, the refining temperature is 720°C to 740°C, and after the aluminum alloy raw materials in the melting furnace are completely melted, they are uniformly stirred by a stirring device.

[0027] A preparation method of a high-temperature resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to some embodiments of the present application. In step S4, a horizontal 2750T extrusion press is used as the extrusion equipment.

[0028] A preparation method of a high-temperature resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to some embodiments of the present application. In step S4, the heating temperature of the extrusion die is 480°C to 500°C, the heating temperature of the extrusion cylinder is 420°C to 440°C, and the heating temperature of the round ingot is 440°C to 460°C.

[0029] A preparation method of a high-temperature resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to some embodiments of the present application. In step S4, the extrusion speed is 3 m / min to 5 m / min.

[0030] A preparation method of a high-temperature resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to some embodiments of the present application. In step S5, air-cooling quenching is used for quenching.

[0031] A preparation method of a high-temperature resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to some embodiments of the present application. In step S6, the aging treatment aging regime is 160°C to 170°C × 6 h.

[0032] The third aspect of the present invention provides a high-temperature resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis prepared by the above preparation method.

[0033] A high-temperature resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis and a preparation method thereof proposed by the present invention significantly improve the corrosion resistance of the profile for an automobile chassis in a high-temperature environment by optimizing the alloy composition, adjusting the homogenization regime, and extrusion process parameters. Specifically, by fine-tuning the chemical composition of the alloy, optimizing the homogenization treatment process of the ingot, and strictly controlling the key parameters in the extrusion production process, the intergranular corrosion depth of the produced aluminum alloy profile is reduced from more than 150 microns in the traditional process to less than 100 microns under the heat treatment condition of keeping warm at 130°C for 1000 hours, significantly improving the corrosion resistance of the profile for an automobile chassis. This technical breakthrough not only solves the problem of excessive intergranular corrosion depth of the existing 6060 aluminum alloy profile for an automobile chassis in a high-temperature environment but also provides technical support for the high-quality production of new energy vehicle parts. Through the optimized production process, the profiles for an automobile chassis produced meet higher standards in terms of corrosion resistance and mechanical properties, significantly improving the overall quality of new energy vehicles. At the same time, it provides a reliable process reference and technical support for the production of subsequent automobile products with similar requirements. This improvement not only meets the needs of the high-end automobile market but also lays a foundation for the technological progress of China's automobile industry in the fields of lightweight and high-performance materials. Brief Description of the Drawings

[0034] Figure 1 It is a schematic flow chart of a preparation method of a high-temperature resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis in the present invention;

[0035] Figure 2 It is a depth map of corrosion points after intergranular corrosion test in Example 1 of the present invention;

[0036] Figure 3 It is a depth map of corrosion points after intergranular corrosion test in Example 2 of the present invention;

[0037] Figure 4 It is a depth map of corrosion points after intergranular corrosion test in Example 3 of the present invention;

[0038] Figure 5 It is a depth map of corrosion points after intergranular corrosion test in Comparative Example 1 of the present invention;

[0039] Figure 6 It is a depth map of corrosion points after intergranular corrosion test in Comparative Example 2 of the present invention;

[0040] Figure 7 It is a depth map of corrosion points after intergranular corrosion test in Comparative Example 3 of the present invention;

[0041] Figure 8 It is a depth map of corrosion points after intergranular corrosion test in Comparative Example 4 of the present invention. Detailed Description of the Invention

[0042] The endpoints and any values disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and a single point value, and between single point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0043] At the present stage, there is little research on the corrosion resistance of automotive aluminum profiles in China after long-term heat treatment. Under the heat treatment conditions of holding at 130°C for 1000 hours for the profiles of 6060 alloy used for automotive chassis produced actually, the intergranular corrosion depth is greater than 150 μm, which seriously affects the production and development of high-end automotive parts in China.

[0044] Therefore, in the first aspect of the present invention, a high-temperature resistant and corrosion-resistant  6-series aluminum alloy profile for an automobile chassis is provided. The components and their weight percentages in the profile for the automobile chassis are as follows:

[0045] The Si content is 0.35% - 0.40%;

[0046] The Fe content is 0.10% - 0.20%;

[0047] The Cu content is ≤ 0.03%;

[0048] The Mn content is 0.05% - 0.10%;

[0049] The Mg content is 0.50% - 0.55%;

[0050] The Cr content is ≤ 0.05%;

[0051] The Zn content is ≤ 0.05%;

[0052] The Ti content is ≤ 0.10%;

[0053] The Zr content is 0.03% - 0.05%;

[0054] The content of a single impurity is ≤ 0.05%;

[0055] The total impurity content is ≤ 0.15%;

[0056] The balance is Al.

[0057] In the present invention, by appropriately reducing the Si content, the segregation of excess Si at the grain boundaries is avoided, thereby preventing the enhancement of intergranular corrosion sensitivity; by moderately increasing the Mg content, Mg can form stable compounds with aluminum, and these compounds may form a dense oxide protective film on the surface of the aluminum alloy, which can improve the corrosion resistance of the profile, but the Mg content should not be too high, because when the Mg content is too high, the precipitated Mg2Si phase will coarsen at the grain boundaries, affecting the corrosion resistance of the alloy; at the same time, a small amount of Zr is added to the alloy composition in the present invention. Al and Zr will form Al3Zr particles inside the grains or at the grain boundaries. The Al3Zr particles located at the grain boundaries will pin the movement of the grain boundaries, and the Al3Zr particles located inside the grains will pin the climb and slip of the dislocations, forming a stable substructural deformation microstructure, thereby preventing the recrystallization growth of the alloy during the solution treatment process, refining the grains, increasing the number of grain boundaries, and further reducing the corrosion sensitivity of the alloy. In the present invention, the Cu content is also strictly controlled. If the Cu content is too high, the CuAl2 phase will precipitate at the grain boundaries, reducing the intergranular corrosion resistance of the alloy.

[0058] The second aspect of the present invention provides a preparation method for a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automotive chassis, as Figure 1 shown, including the following steps:

[0059] S1. Batching to obtain the aluminum alloy raw materials;

[0060] S2. Melting and casting: Put the prepared aluminum alloy raw materials into a melting furnace for melting and casting to obtain a cast bar;

[0061] S3. Ingot homogenization: The cast ingot is homogenized to obtain a round ingot. The homogenization regime during homogenization is 565 °C to 575 °C × 6 h, and after being taken out of the furnace, it is rapidly cooled to room temperature by water mist. In combination with the ratio of the alloying elements Mg and Si contents, high-temperature homogenization is used in the present invention, which can eliminate dendritic segregation in the ingot, enrich the Mg element between dendrites, dissolve coarse non-equilibrium phases, dissolve part of Cu in the matrix, reduce its segregation at grain boundaries, and reduce corrosion sensitivity. After the round ingot is taken out of the furnace and rapidly cooled, the continuity of grain boundary precipitates can be reduced, the grain boundary precipitates are dispersed, the precipitate-free zone is narrow, and the corrosion resistance of the profiles for automotive chassis is further improved.

[0062] S4. Extrusion: The round ingot is placed in an extrusion device for extrusion forming to obtain aluminum alloy profiles.

[0063] S5. Quenching: The aluminum alloy profiles are quenched.

[0064] S6. Aging treatment: The quenched aluminum alloy profiles are subjected to aging treatment to obtain profiles for automotive chassis.

[0065] According to the present invention, in step S2, more preferably, the melting temperature during melting and casting is 700 °C to 720 °C, the refining temperature is 720 °C to 740 °C, and after the aluminum alloy raw materials in the melting furnace are completely melted, they are evenly stirred by a stirring device.

[0066] According to the present invention, in step S4, more preferably, a horizontal 2750T extrusion press is used as the extrusion device. The heating temperature of the extrusion die is 480 °C to 500 °C, the heating temperature of the extrusion cylinder is 420 °C to 440 °C, the heating temperature of the round ingot is 440 °C to 460 °C, and the extrusion speed is 3 m / min to 5 m / min. Low-bar-temperature extrusion production is used to avoid the coarsening of local grain boundary precipitates caused by too high bar temperature, forming corrosion-sensitive areas and reducing the corrosion resistance of the profiles.

[0067] According to the present invention, in step S5, more preferably, air-cooling quenching is used for quenching.

[0068] According to the present invention, in step S6, more preferably, the aging regime for aging treatment is 160 °C to 170 °C × 6 h. The aging temperature should not be too high to avoid an increase in the number of precipitates, too large precipitate sizes and uneven distribution. A poor alloy element zone will be formed around the coarse precipitates. In a corrosive environment, the poor zone will be preferentially corroded as the anode, accelerating the occurrence of intergranular corrosion and reducing the intergranular corrosion resistance of the profiles for automotive chassis.

[0069] The third aspect of the present invention provides a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automotive chassis prepared by the above preparation method.

[0070] By fine-tuning the composition of 6060 alloy, adjusting the homogenization system, and debugging the extrusion production process, the present invention designs a new production system, enabling the depth of intergranular corrosion of the profiles for automotive chassis produced to be less than 150 μm under the heat treatment condition of maintaining at 130 °C for 1000 h, providing technical support for the production of subsequent automotive products with similar requirements.

[0071] The following further describes in detail the embodiments of the present invention in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0072] Example 1. This example provides a preparation method for a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automotive chassis, including the following steps:

[0073] Batching: Prepare aluminum alloy raw materials according to the following weight ratio: Si content is 0.37%; Fe content is 0.12%; Cu content is 0.01%; Mn content is 0.08%; Mg content is 0.53%; Cr content is 0.03%; Zn content is 0.003%; Ti content is 0.05%; Zr content is 0.04%; the content of a single impurity ≤ 0.05%; the total impurity content ≤ 0.15%; the balance is Al.

[0074] Melting and casting: Put the prepared aluminum alloy raw materials into a melting furnace for melting and casting to obtain a cast rod. The melting temperature during melting and casting is 700 °C - 720 °C, the refining temperature is 720 °C - 740 °C, and after the aluminum alloy raw materials in the melting furnace are completely melted, they are evenly stirred by a stirring device.

[0075] Homogenization of the cast rod: Homogenize the cast rod to obtain a round ingot, and the homogenization system in the homogenization treatment is 570 °C × 6 h.

[0076] Extrusion: Put the round ingot into an extrusion device for extrusion molding to obtain an aluminum alloy profile. During extrusion, a horizontal 2750T extrusion press is used for production. The heating temperature of the round ingot is 450 °C, the heating temperature of the extrusion die is 490 °C, and the temperature of the extrusion cylinder is 430 °C.

[0077] Quenching: Quench the aluminum alloy profile, and air-cooling quenching is used for quenching.

[0078] Aging treatment: Perform aging treatment on the quenched aluminum alloy profile. The aging system for the aging treatment is 165 °C × 6 h to obtain the profile for automotive chassis.

[0079] Intergranular corrosion test: Randomly select specimens from the obtained profiles for automotive chassis for testing. Testing equipment: DK-98-H electrothermal constant temperature water bath. Testing method: GB / T7998-2005 Determination method for intergranular corrosion of aluminum alloys. Testing standard: Intergranular corrosion ≤ 150 μm.

[0080] As Figure 2 shown, after testing, the intergranular corrosion depth of the profile for automotive chassis prepared by the method of this embodiment is 62 μm under the heat treatment condition of maintaining at 130 °C for 1000 h.

[0081] Example 2: This example provides a preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automotive chassis. The preparation method used in Example 1 is adopted. The difference from Example 1 is that the ingredients in this example are: Si content is 0.35%; Fe content is 0.13%; Cu content is 0.01%; Mn content is 0.06%; Mg content is 0.50%; Cr content is 0.03%; Zn content is 0.002%; Ti content is 0.05%; Zr content is 0.03%; the content of single impurity ≤ 0.05%; the total impurity content ≤ 0.15%; the balance is Al.

[0082] Intergranular corrosion test: Samples are randomly selected from the prepared profiles for automotive chassis for testing. Testing equipment: DK-98-H electrothermal constant temperature water bath. Testing method: GB / T7998-2005 Determination method for intergranular corrosion of aluminum alloys. Testing standard: Intergranular corrosion ≤ 150 μm.

[0083] As Figure 3 shown, after testing, the intergranular corrosion depth of the profile for automotive chassis prepared by the method of this embodiment is 74.58 μm under the heat treatment condition of maintaining at 130 °C for 1000 h.

[0084] Example 3: This example provides a preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automotive chassis. The preparation method used in Example 1 is adopted. The difference from Example 1 is that the ingredients in this example are: Si content is 0.40%; Fe content is 0.20%; Cu content is 0.03%; Mn content is 0.10%; Mg content is 0.55%; Cr content is 0.05%; Zn content is 0.05%; Ti content is 0.10%; Zr content is 0.05%; the content of single impurity ≤ 0.05%; the total impurity content ≤ 0.15%; the balance is Al.

[0085] Intergranular corrosion test: Samples are randomly selected from the prepared profiles for automotive chassis for testing. Testing equipment: DK-98-H electrothermal constant temperature water bath. Testing method: GB / T7998-2005 Determination method for intergranular corrosion of aluminum alloys. Testing standard: Intergranular corrosion ≤ 150 μm.

[0086] As Figure 4As shown, after testing, the intergranular corrosion depth of the profile for automotive chassis prepared by the method of this embodiment is 80.00 μm under the heat treatment condition of being kept at 130 °C for 1000 h.

[0087] Comparative Example 1: This comparative example provides a preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automotive chassis. The preparation method used in Example 1 is adopted. The difference from Example 1 is that in this comparative example, the ingredient ratio is as follows: Si content is 0.56%; Fe content is 0.20%; Cu content is 0.04%; Mn content is 0.05%; Mg content is 0.57%; Cr content is 0.03%; Zn content is 0.05%; Ti content is 0.03%; the content of each single impurity ≤ 0.05%; the total impurity content ≤ 0.15%; the balance is Al.

[0088] Intergranular corrosion test: Samples are randomly selected from the prepared profiles for automotive chassis for testing. Testing equipment: DK-98-H electrothermal constant temperature water bath. Testing method: GB / T7998-2005 Determination method for intergranular corrosion of aluminum alloys. Testing standard: Intergranular corrosion ≤ 150 μm.

[0089] As Figure 5 shown, after testing, the intergranular corrosion depth of the profile for automotive chassis prepared by the method of this embodiment is 200.10 μm under the heat treatment condition of being kept at 130 °C for 1000 h.

[0090] Comparative Example 2: This comparative example provides a preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automotive chassis. The preparation method used in Example 1 is adopted. The difference from Example 1 is that in this comparative example, during the homogenization of the cast rod, low-temperature homogenization is used, the homogenization treatment temperature is 490 °C, and the holding time is 12 h.

[0091] Intergranular corrosion test: Samples are randomly selected from the prepared profiles for automotive chassis for testing. Testing equipment: DK-98-H electrothermal constant temperature water bath. Testing method: GB / T7998-2005 Determination method for intergranular corrosion of aluminum alloys. Testing standard: Intergranular corrosion ≤ 150 μm.

[0092] As Figure 6 shown, after testing, the intergranular corrosion depth of the profile for automotive chassis prepared by the method of this embodiment is 186.44 μm under the heat treatment condition of being kept at 130 °C for 1000 h.

[0093] Comparative Example 3 provided a preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automobile chassis. The preparation method adopted in Example 1 was used. The difference from Example 1 was that in the extrusion of this comparative example, the heating temperature of the round ingot was 500 °C, the heating temperature of the extrusion die was 500 °C, the temperature of the extrusion cylinder was 440 °C, air cooling was used, and the extrusion speed was 5 m / min.

[0094] Intergranular corrosion test: Specimens were randomly selected from the prepared profiles for automobile chassis for testing. Testing equipment: DK-98-H electrothermal constant temperature water bath. Testing method: GB / T7998-2005 Determination method for intergranular corrosion of aluminum alloys. Testing standard: Intergranular corrosion ≤ 150 μm.

[0095] As Figure 7 shown, after testing, the intergranular corrosion depth of the profile for automobile chassis prepared by the method of this example was 179.66 μm under the heat treatment condition of maintaining at 130 °C for 1000 h.

[0096] Comparative Example 4 provided a preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automobile chassis. The preparation method adopted in Example 1 was used. The difference from Example 1 was that in the aging treatment of this comparative example, the aging regime was 180 °C × 8 h.

[0097] Intergranular corrosion test: Specimens were randomly selected from the prepared profiles for automobile chassis for testing. Testing equipment: DK-98-H electrothermal constant temperature water bath. Testing method: GB / T7998-2005 Determination method for intergranular corrosion of aluminum alloys. Testing standard: Intergranular corrosion ≤ 150 μm.

[0098] As Figure 8 shown, after testing, the intergranular corrosion depth of the profile for automobile chassis prepared by the method of this example was 181.02 μm under the heat treatment condition of maintaining at 130 °C for 1000 h.

[0099] The embodiments of the present invention are given for purposes of illustration and description, and are not exhaustive or limit the present invention to the disclosed form. Many modifications and variations are obvious to those of ordinary skill in the art. The embodiments are selected and described to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and thus design various embodiments with various modifications suitable for specific purposes.

Claims

1. A heat-resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis, characterized in that, The components and their weight percentages in the profile for automobile chassis are as follows: The Si content is 0.35% - 0.40%; The Fe content is 0.10% - 0.20%; The Cu content ≤ 0.03%; The Mn content is 0.05% - 0.10%; The Mg content is 0.50% - 0.55%; The Cr content ≤ 0.05%; The Zn content ≤ 0.05%; The Ti content ≤ 0.10%; The Zr content is 0.03% - 0.05%; The content of a single impurity ≤ 0.05%; The total impurity content ≤ 0.15%; The balance is Al.

2. A preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to claim 1, characterized in that It includes the following steps: S1. Batching to obtain the aluminum alloy raw material; S2. Melting and casting: Put the prepared aluminum alloy raw material into a melting furnace for melting and casting to obtain a casting rod; S3. Homogenization of the casting rod: Carry out homogenization treatment on the casting rod to obtain a round ingot. The homogenization system in the homogenization treatment is 565°C - 575°C × 6h, and it is cooled to room temperature by water mist after being taken out of the furnace; S4. Extrusion: Put the round ingot into an extrusion device for extrusion molding to obtain an aluminum alloy profile; S5. Quenching: Carry out quenching treatment on the aluminum alloy profile; S6. Aging treatment: Carry out aging treatment on the quenched aluminum alloy profile to obtain the profile for automobile chassis.

3. The preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to claim 2, characterized in that, In the step S2, the melting temperature during melting and casting is 700°C - 720°C, the refining temperature is 720°C - 740°C, and after the aluminum alloy raw material in the melting furnace is completely melted, it is evenly stirred by a stirring device.

4. The preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to claim 2, characterized in that, In the step S4, the extrusion device uses a horizontal 2750T extrusion press.

5. The preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to claim 2, characterized in that, In the step S4, the heating temperature of the extrusion die is 480°C - 500°C, the heating temperature of the extrusion cylinder is 420°C - 440°C, and the heating temperature of the round ingot is 440°C - 460°C.

6. The preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to claim 2, characterized in that, In the step S4, the extrusion speed is 3m / min - 5m / min.

7. The preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to claim 2, characterized in that, In the step S5, air-cooling quenching is used for quenching.

8. The preparation method of a heat-resistant and corrosion-resistant 6-series aluminum alloy profile for an automobile chassis according to claim 2, characterized in that, In the step S6, the aging system of the aging treatment is 160°C - 170°C × 6h.

9. A heat-resistant and corrosion-resistant 6-series aluminum alloy profile for automobile chassis prepared by the preparation method according to any one of claims 2 - 8.

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