High-forming 5-series aluminum alloy sheet strip for automotive air suspension members and method of manufacturing the same

Abstract

The application discloses an air suspension high-forming 5-series aluminum alloy plate strip and a preparation method thereof. The grain size and orientation distribution characteristics of the aluminum alloy plate strip in the thickness direction are as follows: the small-angle grain boundary proportion with an orientation difference range of 2-5 degrees is less than 2%, the large-angle grain boundary proportion with an orientation difference range of 5-180 degrees is greater than or equal to 85%, the rolling texture proportion is less than 15%, and the total texture proportion of typical orientations is less than 50%. The preparation method is as follows: ① melting and semi-continuous casting; ② ingot heating treatment; ③ hot rolling; ④ cold rolling; and ⑤ product annealing. The scheme controls the anisotropy of the 5-series aluminum alloy plate strip for air suspension, and improves the yield of the 5-series aluminum alloy plate strip for air suspension.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy materials, specifically relating to a high-formability 5-series aluminum alloy sheet and strip for air suspension and its preparation method. Background Technology

[0002] With the booming development of the automotive industry in recent years, lightweighting of automobiles has become an inevitable trend. Aluminum alloys, with their advantages of light weight, high strength, and good plasticity, have enabled the replacement of steel in many automotive parts. Air suspension components are an important part of automotive suspension, which can buffer the impact forces transmitted from the road surface to the chassis or body, ensuring stable vehicle operation. Aluminum alloy stamped parts are lightweight, have moderate strength, good formability, and low cost, which can meet the requirements of complex shapes and thin walls in automotive air suspension components.

[0003] Aluminum alloys are typically used for the shock absorber housings in automotive air suspension components. The aluminum sheet / strip must maintain a smooth and flat surface after bending or stamping, and the plastically formed areas must be free of defects such as cracks and pits. The stamped blank shell must also have high cross-sectional roundness. Adding a certain proportion of magnesium (Mg) to the aluminum alloy can further reduce its density, achieving weight reduction, and significantly improve the strength and elastic modulus of the aluminum alloy sheet / strip. Furthermore, by appropriately adding certain proportions of manganese (Mn), chromium (Cr), and copper (Cu), the strength and formability of the aluminum alloy material can be improved. However, stamped blanks made from 5-series aluminum alloy sheets / strips often exhibit high cross-sectional roundness, with diameters differing by 1–3 mm at 0° and 90° angles from the rolling direction. In some cases, punching cracks even occur, leading to product scrap, making it difficult to meet the aluminum requirements of automotive air suspension components. Summary of the Invention

[0004] To achieve the above objectives and solve the problems existing in the prior art, this invention provides a high-formability 5-series aluminum alloy sheet / strip for air suspension and its preparation method. This solution improves the yield of 5-series aluminum alloy sheet / strip for air suspension by controlling the anisotropy of the sheet / strip.

[0005] One objective of this invention is to provide a high-formability 5-series aluminum alloy sheet / strip for air suspension. The grain size and orientation distribution characteristics of the aluminum alloy sheet / strip in the thickness direction are as follows: small-angle grain boundaries account for <2%, large-angle grain boundaries account for ≥85%, rolling texture accounts for <15%, and total typical orientation texture accounts for <50%. Among these, the rolling texture includes Brass texture, S texture, and Copper texture; the total typical orientation texture includes: P texture, R texture, F texture, Brass texture, S texture, CopperR-Cube texture, Goss texture, Q texture, and Cube texture.

[0006] As a preferred embodiment, the aluminum alloy sheet / strip comprises the following components by mass percentage: 2.5% ≤ Mg < 3.3%; Fe < 0.15%; Si < 0.15%; Zn < 0.1%; 0.08% ≤ Cr < 0.3%; 0.05% ≤ Cu < 0.15%; 0.15% ≤ Mn < 0.45%; Ti ≤ 0.04%, with the balance being Al and unavoidable impurities.

[0007] As a preferred embodiment, the aluminum alloy sheet / strip has a tensile strength of 220–240 MPa and a yield strength of 105–120 MPa.

[0008] As a preferred embodiment, the elongation of the aluminum alloy sheet / strip is ≥24%, and the difference in elongation between the sheet and the rolling direction at 0° and 90° is ≤0.5%.

[0009] The second objective of this invention is to provide a method for preparing high-formability 5-series aluminum alloy sheet and strip for air suspension.

[0010] Step ①: Melting and semi-continuous casting. The prepared aluminum alloy raw materials are added to the melting furnace and mixed evenly to melt into liquid aluminum alloy. The liquid aluminum alloy is then semi-continuously cast into ingots.

[0011] Step 2: Heat the obtained ingots;

[0012] Step 3: The heat-treated ingot is hot-rolled to obtain hot-rolled slab;

[0013] Step 4: The hot-rolled slab is cold-rolled to obtain a cold-rolled sheet of a certain thickness, and intermediate annealing is performed during the cold rolling process;

[0014] Step 5: Anneal the cold-rolled sheet to obtain 5-series aluminum alloy sheet and strip.

[0015] As a preferred embodiment, in step ① of the preparation method, the melting and semi-continuous casting are carried out at a melting temperature of 740–755℃, a semi-continuous casting temperature of 685–705℃, a stable ingot production speed of 44–53 mm / min, and a crystallizer cooling water flow rate of 141–156 m³ / min. 3 / h, cooling water temperature 10~30℃.

[0016] As a preferred embodiment, in step ②, the ingot is heat-treated, wherein after the ingot is cut at the head and tail and milled, it is heated in a box-type heating furnace at a heating temperature of 490℃~530℃ and a holding time of 12~24h.

[0017] As a preferred embodiment, in step ③, the heated ingot is hot-rolled into a 7-10 mm hot-rolled slab, wherein the initial rolling temperature is 440-510℃ and the final rolling temperature is 270-360℃.

[0018] As a preferred embodiment, in step ④, the hot-rolled slab is cold-rolled to obtain a finished plate with a thickness of 1-3 mm, and the total cold-rolling deformation is 68%-73%.

[0019] As a preferred embodiment, step ⑤ involves annealing the cold-rolled sheet to a certain thickness at a temperature of 270–350°C.

[0020] The present invention has at least the following beneficial effects:

[0021] Firstly, this invention optimizes the manufacturing process of aluminum alloy sheet and strip. By strictly controlling the rolling and annealing processes, the anisotropy of the aluminum material is controlled. After testing, the elongation difference between the prepared aluminum sheet and strip at 0° and 90° with respect to the rolling direction is ≤0.5%, effectively improving the yield of 5-series aluminum alloy sheet and strip for air suspension.

[0022] Secondly, by controlling the rolling and annealing processes, this invention promotes complete recrystallization of the central grains in the strip, ensuring uniformity between the surface and central grains. This results in aluminum strips having high mechanical properties while significantly improving formability, with a yield strength of 220–240 MPa, a yield strength of 105–120 MPa, and an elongation of 24%–28%, meeting the technical requirements of high formability of aluminum alloy strips for air suspension related products. Attached Figure Description

[0023] Figure 1 The grain morphology of the longitudinal section of the finished aluminum alloy sheet with a total cold rolling deformation of 69.5% and a finished annealing temperature of 275℃ (Example 1).

[0024] Figure 2 The longitudinal section texture distribution of the finished aluminum alloy sheet with a total cold rolling deformation of 69.5% and a finished product annealing temperature of 275℃ is shown in Example 1.

[0025] Figure 3 The grain morphology of the longitudinal section of the finished aluminum alloy sheet with a total cold rolling deformation of 62.5% and a finished annealing temperature of 295℃ is shown in Comparative Example 1.

[0026] Figure 4 The longitudinal section texture distribution of the finished aluminum alloy sheet with a total cold rolling deformation of 62.5% and a finished product annealing temperature of 295℃ is shown in Comparative Example 1.

[0027] Figure 5 Table 1 shows the grain boundary orientation difference distribution data of the 5-series aluminum alloy plates prepared in Examples 1-3 and Comparative Examples 1-2.

[0028] Figure 6 Table 2 shows the rolling texture and total texture ratio of the 5-series aluminum alloy sheets prepared in Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0029] To make the technical means, creative features, objectives, and beneficial effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0030] This embodiment provides a high-formability 5-series aluminum alloy sheet / strip for air suspension. The grain size and orientation distribution characteristics in the thickness direction of the aluminum alloy sheet / strip are as follows: small-angle grain boundaries account for <2%, and large-angle grain boundaries account for ≥85%. Specifically, adjacent orientation differences of 2–5° constitute small-angle grain boundaries, and adjacent orientation differences of 5–180° constitute large-angle grain boundaries. The grain boundary percentage is the percentage of the grain boundary length within the corresponding orientation difference range to the total grain boundary length. The rolled texture percentage is <15%, and the total texture percentage for typical orientations is <50%. Rolled textures include Brass texture, S texture, and Copper texture; the total texture for typical orientations includes: P texture, R texture, F texture, Brass texture, S texture, CopperR-Cube texture, Goss texture, Q texture, and Cube texture. Texture is calculated based on area, and the texture percentage is a percentage of the area of ​​one texture to the total texture area.

[0031] In this scheme, the aluminum alloy sheet and strip have the following composition by mass percentage: 2.5% ≤ Mg < 3.3%; Fe < 0.15%; Si < 0.15%; Zn < 0.1%; 0.08% ≤ Cr < 0.3%; 0.05% ≤ Cu < 0.15%; 0.15% ≤ Mn < 0.45%; Ti ≤ 0.04%, with the balance being Al and unavoidable impurities. By rationally adding a certain proportion of Mn, Cr, and Cu elements, the strength and formability of the aluminum alloy material are improved.

[0032] In this design, the aluminum alloy sheet / strip has a tensile strength of 220–240 MPa and a yield strength of 105–120 MPa.

[0033] In this embodiment, the elongation of the aluminum alloy sheet / strip is ≥24%, and the difference in elongation between 0° and 90° of the rolling direction is ≤0.5%. In the prior art, the blanks of aluminum alloy sheets / strips often exhibit high cross-sectional non-roundness after stamping. This problem is solved by controlling the difference in elongation between 0° and 90° of the rolling direction to be ≤0.5%.

[0034] This embodiment also provides a method for preparing high-formability 5-series aluminum alloy sheet and strip for air suspension.

[0035] The technical route is as follows: ① Smelting and semi-continuous casting; ② Ingot heat treatment; ③ Hot rolling; ④ Cold rolling; ⑤ Finished product annealing. By controlling the rolling and annealing processes, complete recrystallization of the central grains in the strip is promoted, ensuring uniformity between the surface and central grains, and controlling the anisotropy of the strip.

[0036] The specific preparation steps for the aluminum alloy sheet / strip are as follows:

[0037] ① Melting and semi-continuous casting steps; the melting temperature is 740-755℃, the raw materials consist of 30%-50% primary scrap (including 5-series alloy ingots, hot-rolled plate ends, thick plate scrap, etc.), 15%-25% secondary scrap (including 5-series alloy thin plate scrap and trimmings, etc.), and the remaining raw materials are mainly industrial pure aluminum, industrial pure magnesium, and intermediate alloys or fluxes of Al-Mn, Al-Cr, etc. The semi-continuous casting temperature is 685-705℃, the stable ingot production speed is 44-53 mm / min, and the crystallizer cooling water flow rate is 141-156 m³ / min. 3 / h, cooling water temperature 10~30℃.

[0038] ② Ingot heating treatment steps; after the ingot is cut off at the head and tail and milled, it is heated in a box furnace at a temperature of 490℃~530℃ and held for 12~24h.

[0039] ③ Hot rolling step: The heated ingot is hot rolled into a 7-10 mm hot rolled slab, with an initial rolling temperature of 440-510℃ and a final rolling temperature of 270-360℃.

[0040] ④ Cold rolling step; cold rolling yields a finished sheet with a thickness of 1-3 mm, with a total cold rolling deformation of 68%-73%.

[0041] ⑤ Finished product annealing step; The sheet material cold-rolled to the finished product thickness in step ④ of the preparation method is annealed at a temperature of 270~350℃.

[0042] This invention controls the grain size and orientation distribution characteristics of aluminum sheet in the thickness direction through rolling and annealing processes: small-angle grain boundaries account for <2%, large-angle grain boundaries account for ≥85%; rolling texture accounts for <15%, and total texture of typical orientations accounts for <50%. Ultimately, it achieves a tensile strength of 220–240 MPa, a yield strength of 105–120 MPa, an elongation of ≥24%, and an elongation difference (between 0° and 90° in the rolling direction) of ≤0.5%, meeting the technical requirements for high formability of aluminum alloy sheet and strip in the stamping process of automotive air suspension components.

[0043] Example 1

[0044] A high-formability 5-series aluminum alloy sheet / strip for air suspension is formulated with the following alloy composition: Si = 0.08%; Fe = 0.10%; Cu = 0.11%; Mn = 0.25%; Mg = 2.82%; Cr = 0.18%; Zn = 0.02%; Ti = 0.03%, with the balance being Al and unavoidable impurities.

[0045] The preparation method of this aluminum alloy sheet and strip includes the following steps:

[0046] (1) Melting and semi-continuous casting: Melting temperature 746℃, Mg ingots are added to the feed frame and pressed into the melt for stirring, primary waste accounts for 32%, secondary waste accounts for 18%, high-purity Ar gas is used for refining and degassing the melt, and plate-type double-stage filtration and tubular filtration are used for filtration, semi-continuous casting temperature 696℃, casting speed 48mm / min, crystallizer cooling water flow rate 147m³ / min. 3 / h, cooling water temperature 21℃;

[0047] (2) Heat treatment of ingots: After the head and tail of the ingots are cut off, the upper and lower surfaces are milled by 10mm. The heating temperature is 495℃ and the holding time is 20h.

[0048] (3) Hot rolling: initial rolling temperature 480℃, final rolling temperature 345℃, hot rolled slab 7.3mm;

[0049] (4) Cold rolling: The thickness of the 7.3mm sheet is reduced to 2.4mm for the finished sheet, and the total deformation during cold rolling is 69.5%;

[0050] (5) Anneal the finished thickness plate at a temperature of 275℃.

[0051] Figures 1-2 The images show the grain morphology and texture distribution of the longitudinal section of a high-formability 5-series aluminum alloy sheet prepared in Example 1 with a total cold rolling deformation of 69.5% and a finished product annealing temperature of 275℃. (EBSD experiments were performed using a JSM6460 scanning electron microscope; the sample cross-sectional size should not exceed 50mm × 50mm, and the selected step size was 2.5μm. The EBSD data were analyzed using TSL OIM Analysis5 software to obtain the grain morphology, grain orientation difference, and texture type and proportion of the longitudinal section of the sheet). It can be seen that the aluminum alloy sheet prepared by this process exhibits a fully recrystallized morphology in both the surface and central grains after finished product annealing. The grain distribution is uniform with no coarse grains, and the average grain size is 23μm.

[0052] Tables 1 and 2 show the statistical results of grain orientation difference and texture of the longitudinal section of 5-series aluminum alloy finished sheets. It can be seen that the aluminum alloy sheets prepared by this process have a small number of small-angle grain boundaries and a low proportion, and the proportion of rolling texture is small and the total texture ratio is small. This indicates that the aluminum alloy sheets prepared by this process have sufficient recrystallization and small anisotropy, which is beneficial to improving the cross-sectional roundness of the subsequent sheet stamping into shells.

[0053] The aluminum alloy sheet and strip produced by this process has a tensile strength of 238 MPa, a yield strength of 112 MPa, and an elongation of 26.4%. The difference in elongation between 0° and 90° with respect to the rolling direction of the sheet is 0.4%. It has excellent strength and formability, which meets the technical requirements of high formability of aluminum alloy sheet and strip for air suspension related products.

[0054] Example 2

[0055] A high-formability 5-series aluminum alloy sheet / strip for air suspension is formulated with the following alloy composition: Si = 0.07%; Fe = 0.11%; Cu = 0.09%; Mn = 0.39%; Mg = 3.17%; Cr = 0.10%; Zn = 0.08%; Ti = 0.03%, with the balance being Al and unavoidable impurities.

[0056] The preparation method of this aluminum alloy sheet and strip includes the following steps:

[0057] (1) Melting and semi-continuous casting: Melting temperature 750℃, Mg ingots are added to the feed frame and pressed into the melt for stirring, primary waste accounts for 49% and secondary waste accounts for 21%, high-purity Ar gas is used for refining and degassing the melt, and plate-type double-stage filtration and tubular filtration are used for filtration, semi-continuous casting temperature 700℃, casting speed 52mm / min, and crystallizer cooling water flow rate 156m³ / min. 3 / h, cooling water temperature 26℃;

[0058] (2) Heat treatment of ingots: After the head and tail of the ingots are cut off, the upper and lower surfaces are milled by 10 mm. The heating temperature is 523℃ and the holding time is 19h.

[0059] (3) Hot rolling: initial rolling temperature 500℃, final rolling temperature 285℃, hot rolled slab 8.1mm;

[0060] (4) Cold rolling: The thickness of the 8.1mm sheet is reduced to 2.3mm for the finished sheet, with a total deformation of 71.6% during cold rolling;

[0061] (5) Anneal the finished thickness plate at a temperature of 340℃.

[0062] The high-strength, high-formability aluminum sheet and strip produced by this process has a tensile strength of 235 MPa, a yield strength of 110 MPa, and an elongation of 27.2%. The difference in elongation between 0° and 90° with respect to the rolling direction of the sheet is 0.2%, which meets the technical requirements of high formability of aluminum alloy sheet and strip for air suspension related products.

[0063] Example 3

[0064] A high-formability 5-series aluminum alloy sheet / strip for air suspension is formulated with the following alloy composition: Si = 0.09%; Fe = 0.12%; Cu = 0.12%; Mn = 0.30%; Mg = 3.05%; Cr = 0.20%; Zn = 0.04%; Ti = 0.03%, with the balance being Al and unavoidable impurities.

[0065] The preparation method of this aluminum alloy sheet and strip includes the following steps:

[0066] (1) Melting and semi-continuous casting: Melting temperature 752℃, Mg ingots are added to the feed frame and pressed into the melt for stirring, primary waste accounts for 45%, secondary waste accounts for 19%, high-purity Ar gas is used for refining and degassing the melt, and plate-type double-stage filtration and tubular filtration are used for filtration, semi-continuous casting temperature 703℃, casting speed 50mm / min, and crystallizer cooling water flow rate 152m³ / min. 3 / h, cooling water temperature 28℃;

[0067] (2) Heat treatment of ingots: After the head and tail of the ingots are cut off, the upper and lower surfaces are milled by 10mm. The heating temperature is 510℃ and the holding time is 22h.

[0068] (3) Hot rolling: initial rolling temperature 470℃, final rolling temperature 300℃, hot rolled slab 7.5mm;

[0069] (4) Cold rolling: The thickness of the 7.5mm sheet is reduced to 2.2mm for the finished sheet, and the total deformation during cold rolling is 70.6%;

[0070] (5) Anneal the finished thickness plate at a temperature of 320℃.

[0071] The high-strength, high-formability aluminum sheet and strip produced by this process has a tensile strength of 230 MPa, a yield strength of 106 MPa, and an elongation of 27.5%. The difference in elongation between 0° and 90° with respect to the rolling direction of the sheet is 0.1%, which meets the technical requirements of high formability of aluminum alloy sheet and strip for air suspension related products.

[0072] Table 1

[0073]

[0074]

[0075] In Table 1, the grain boundary percentage is the percentage of the grain boundary length in the corresponding orientation difference range to the total grain boundary length. In this scheme, the grain boundary orientation difference range of 2 to 5° is a small-angle grain boundary, and the grain boundary orientation difference range of 5 to 180° is a large-angle grain boundary.

[0076] Table 2

[0077]

[0078] In Table 2, the rolling texture includes Brass texture, S texture, and Copper texture; the typical orientation total texture includes: P texture, R texture, F texture, Brass texture, S texture, CopperR-Cube texture, Goss texture, Q texture, and Cube texture.

[0079] Comparative Example 1

[0080] The comparative example uses aluminum material with the same composition as in Example 1, with a total cold rolling deformation of 62.5%, a finished product annealing temperature of 295°C, and other preparation process conditions as in Example 1.

[0081] The shock absorber housing in the automotive air suspension component, which is formed by stamping aluminum sheet prepared by this process, has a high degree of non-roundness in its cross-section, with a diameter difference of 1.5 mm between the 0° and 90° angles from the rolling direction of the sheet. Figures 3-4 The photographs show the grain morphology and texture distribution of the longitudinal section of the sheet material prepared by this process. It is evident that the surface layer of the sheet material exhibits an equiaxed grain morphology, while the central region shows a distinct banded grain structure, indicating insufficient recrystallization in the central part of the sheet material, with residual processing structure from before annealing. This is because the total cold rolling deformation is relatively small, resulting in insufficient recrystallization energy storage in the central part, thus preventing complete recrystallization. Table 1 shows the proportion of grain boundary orientation differences in the longitudinal section of 5-series aluminum alloy sheet and strip for air suspension prepared by different methods. It is evident that the aluminum sheet material prepared by this process has a high proportion of small-angle grain boundaries (2°–5°), resulting in high rolling texture and overall texture, indicating strong anisotropy. This makes it prone to uneven deformation during stamping, leading to high shell non-roundness.

[0082] The aluminum sheet and strip prepared by this alloy composition and process has a tensile strength of 209 MPa, a yield strength of 101 MPa, and an elongation of 22.9%. The difference in elongation between 0° and 90° with respect to the rolling direction of the sheet is 2.1%, which does not meet the technical requirements of high formability of aluminum alloy sheet and strip for air suspension related products.

[0083] Comparative Example 2

[0084] The comparative example uses aluminum material with the same composition as Example 1, with a total cold rolling deformation of 69.2%, a finished product annealing temperature of 255°C, and other preparation process conditions the same as in Example 1.

[0085] As can be seen from Tables 1 and 2, the aluminum sheet produced by this process has a high proportion of small-angle grain boundaries, up to 9.5%. At the same time, the rolling texture and total texture ratio are high, and the sheet has strong anisotropy. This can easily lead to uneven deformation during the stamping process, affecting the roundness of the shell and even causing cracks.

[0086] The aluminum strip produced by this process has a tensile strength of 198 MPa, a yield strength of 97 MPa, and an elongation of 20.4%. The difference in elongation between 0° and 90° with respect to the rolling direction is 1.7%, which does not meet the technical requirements of high formability of aluminum alloy strip for air suspension related products.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the specific implementation of the present invention with reference to the above embodiments. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the pending claims.

Claims

1. A method for preparing high-formability 5-series aluminum alloy sheet / strip for air suspension, characterized in that: The grain size and orientation distribution characteristics of the aluminum alloy sheet / strip in the thickness direction are as follows: small-angle grain boundaries account for <2%, large-angle grain boundaries account for ≥85%, rolling texture accounts for <15%, and total texture of typical orientation accounts for <50%; the elongation of the aluminum alloy sheet / strip is ≥24%, and the difference in elongation at 0° and 90° from the rolling direction of the sheet / strip is ≤0.5%; the tensile strength of the aluminum alloy sheet / strip is 220~240MPa, and the yield strength is 105~120MPa; The aluminum alloy sheet and strip have the following composition by weight percentage: 2.5%≤Mg<3.3%; Fe<0.15%; Si<0.15%; Zn<0.1%; 0.08%≤Cr<0.3%; 0.05%≤Cu<0.15%; 0.15%≤Mn<0.45%; Ti≤0.04%, and the balance being Al and unavoidable impurities; The method for preparing the aluminum alloy sheet / strip is as follows: Step ①: Melting and semi-continuous casting. The prepared aluminum alloy raw materials are added to the melting furnace and mixed evenly to melt into liquid aluminum alloy. The liquid aluminum alloy is then semi-continuously cast into ingots. Step 2: Heat the obtained ingots; Step 3: The heat-treated ingot is hot-rolled to obtain a 7-10mm hot-rolled slab billet; Step 4: The hot-rolled slab is cold-rolled to obtain a cold-rolled sheet with a finished thickness of 1-3 mm. The total deformation during cold rolling is 68%-73%. Intermediate annealing is carried out during the cold rolling process. Step 5: The sheet material cold-rolled to the finished thickness is annealed at a temperature of 270~350℃ to obtain 5-series aluminum alloy sheet and strip.

2. The method for preparing a high-formability 5-series aluminum alloy sheet / strip for air suspension according to claim 1, characterized in that: In step ① of the preparation method, the melting and semi-continuous casting processes are carried out at a melting temperature of 740~755℃ and a semi-continuous casting temperature of 685~705℃. The stable ingot production speed is 44~53mm / min, and the cooling water flow rate of the crystallizer is 141~156m³ / min. 3 / h, cooling water temperature 10~30℃.

3. The method for preparing a high-formability 5-series aluminum alloy sheet / strip for air suspension according to claim 1, characterized in that: In step ②, the ingot is heated. After the ingot is cut off and milled, it is heated in a box furnace at a temperature of 490℃~530℃ for 12~24h.

4. The method for preparing a high-formability 5-series aluminum alloy sheet / strip for air suspension according to claim 1, characterized in that: In step ③, the initial rolling temperature is 440~510℃ and the final rolling temperature is 270~360℃.

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