A preparation method for improving the flanging performance of 6-series aluminum alloy automotive sheet metal

Abstract

A method for preparing 6-series aluminum alloy automotive sheet metal with improved flanging performance includes the following steps: Step 1: Selecting raw materials according to the aluminum alloy composition and performing melt casting to obtain an ingot; Step 2: Homogenizing the ingot; Step 3: After homogenization, the ingot is directly hot-rolled after being removed from the furnace; Step 4: After hot rolling and coiling, the ingot is uncoiled using an uncoiler to achieve rapid cooling to 70℃-80℃, followed by cold rolling until the target thickness is achieved; Step 5: Solution treatment is performed after cold rolling; Step 6: Pre-aging treatment is performed after solution treatment to obtain the aluminum alloy sheet metal. This invention employs high-temperature rolling. To avoid the precipitation and coarsening of the Mg2Si phase at grain boundaries, rapid cooling and direct cold rolling are performed after hot rolling and coiling using an uncoiler. This reduces the number of processes and improves time utilization, thereby significantly increasing the production efficiency of the sheet metal.

Description

Technical Field

[0001] This invention belongs to the field of automotive aluminum alloy profiles, specifically a preparation method for improving the flanging performance of 6-series aluminum alloy automotive sheet metal. Background Technology

[0002] With the increasing demand for automobiles, and considering energy consumption and energy structure issues, accelerating the development of lightweight vehicles is crucial for energy conservation and emission reduction. At the same time, existing demands for vehicle safety and comfort are no longer sufficient, and there are also certain requirements for vehicle appearance.

[0003] 6-series aluminum alloys are used for automotive exterior panels due to their corrosion resistance, good formability, and high bake hardening properties. Flanging refers to the process of an outer panel encasing an inner panel, assembling them together, ensuring a crack-free surface, and guaranteeing a smooth finish after painting.

[0004] Chinese Patent No. CN 109868398 B discloses a 6-series aluminum alloy sheet with high flanging performance and its preparation method. The method employs intermediate annealing, and improves flanging performance by controlling the proportion of second-phase particles and grain size in the finished product state. However, the intermediate annealing uses box annealing, which increases the product processing steps and raises production costs.

[0005] Chinese Patent No. CN 111334728 B proposes a method to improve the flanging performance of aluminum alloy sheets. This method controls the size and distribution of the Mg2Si and Si phases by regulating the cooling rate after homogenization treatment and the heating and holding process before hot rolling, thereby improving the flanging performance of the aluminum alloy and reducing the utilization rate of the pusher furnace. However, the use of intermediate annealing increases production costs.

[0006] Chinese Patent No. CN 113070361 A discloses a special hot rolling production method for 6-series automotive sheet metal, which uses high-temperature rolling, but does not provide details on how to carry out the cold rolling process after hot rolling.

[0007] As can be seen from the above existing technologies, although a lot of research has been done on improving the flanging performance of 6-series aluminum alloys, most of it involves intermediate annealing, which increases the number of processes and production costs. Summary of the Invention

[0008] This invention provides a method for improving the flanging performance of 6-series aluminum alloy automotive sheet metal, thereby overcoming the deficiencies in the prior art.

[0009] This invention is achieved through the following technical solution:

[0010] A method for improving the flanging performance of 6-series aluminum alloy automotive sheet metal includes the following steps:

[0011] Step 1: Select the type of raw material according to the aluminum alloy composition and melt and cast it to obtain an ingot;

[0012] Step 2: Homogenize the ingots;

[0013] Step 3: After homogenization, the ingots are directly subjected to hot rolling after being removed from the furnace;

[0014] Step 4: After hot rolling, the coil is uncoiled using an uncoiler to achieve rapid cooling down to 70℃-80℃, followed by cold rolling until the target thickness is achieved;

[0015] Step 5: Solution treatment is performed after cold rolling;

[0016] Step Six: After solution treatment, pre-aging treatment is performed to obtain aluminum alloy sheet.

[0017] The preparation method for improving the flanging performance of 6-series aluminum alloy automotive sheet metal, as described above, comprises the following components: Si 0.58%; Mg 0.6%; Cu 0.1%; Fe 0.2%; Mn 0.1%; Zn 0.007%; Ti 0.02%; with the balance being Al.

[0018] In the preparation method described above for improving the flanging performance of 6-series aluminum alloy automotive sheet metal, the homogenization treatment in step two is carried out at a temperature of 550℃-580℃ for 4-10 hours.

[0019] The preparation method for improving the flanging performance of 6-series aluminum alloy automotive sheet metal, as described above, includes the following steps: hot rolling treatment in step three: initial rolling temperature of 510℃-530℃, rolling using 1+5 rolling, hot rolling coiling temperature of 310℃-400℃, and coiling thickness of 2.5-5mm.

[0020] In the preparation method described above for improving the flanging performance of 6-series aluminum alloy automotive sheet metal, the cold rolling reduction in step four is 60%-80% to ensure surface quality.

[0021] In the preparation method described above for improving the flanging performance of 6-series aluminum alloy automotive sheet metal, the solution temperature in step five is 520℃-580℃, and the holding time is 20s-60s.

[0022] In the preparation method described above for improving the flanging performance of 6-series aluminum alloy automotive sheet metal, the pre-aging temperature in step six is ​​70℃-100℃.

[0023] The advantages of this invention are: High-temperature rolling is employed. To avoid the precipitation and coarsening of the Mg2Si phase at grain boundaries, the hot-rolled coil is rapidly cooled using an uncoiler before direct cold rolling. This reduces the number of processes and improves time utilization, significantly increasing the production efficiency of the sheet material. Simultaneously, it also has a certain impact on the proportion and distribution of small and large grain boundaries in the finished sheet material. Small-angle grain boundaries account for 60%-70%, and 2°-5° small-angle grain boundaries account for 50%-60%, with uniform distribution and good plasticity, which helps improve flanging performance. The TTT curve shows that the nose temperature of the Mg2Si phase is 380℃. A temperature range of 310℃-400℃ is selected as the hot-rolling coiling temperature, and the uncoiler is used after hot rolling to achieve rapid cooling, effectively avoiding the nose temperature for Mg2Si phase precipitation. This helps control the precipitation and coarsening of the Mg2Si phase at grain boundaries, ensuring the formability and strength of the sheet material. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart of the preparation process of the present invention.

[0026] Figure 2 This is the TTT curve of the Mg2Si phase of the present invention.

[0027] Figure 3 This is the Map diagram in Embodiment 1 of the present invention.

[0028] Figure 4 This is the Map diagram in Comparative Example 1 of the present invention.

[0029] Figure 5 This is the Map diagram in Comparative Example 2 of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] The composition of 6-series aluminum alloys is 0.58% Si, 0.6% Mg, 0.1% Cu, 0.2% Fe, 0.1% Mn, 0.007% Zn, 0.02% Ti, etc., with the balance being Al.

[0033] The casting is carried out according to the above composition, and the ingot is homogenized by a process of 580℃ for 4 hours.

[0034] After homogenization, the product is directly subjected to hot rolling at a starting temperature of 530℃.

[0035] The hot rolling process uses a 1+5 rolling method, with a hot rolling coiling temperature of 360℃ and a coiling thickness of 3.5mm.

[0036] After hot rolling, the coil is uncoiled and cooled to 70°C on an uncoiler, and then cold rolled directly on a cold rolling mill.

[0037] After cold rolling, a solution treatment is performed at a temperature of 580℃ for 20 seconds.

[0038] After solution treatment, pre-aging is performed at a temperature of 70℃.

[0039] In Example 1, the small-angle grain boundaries in the finished plate are relatively uniformly distributed, and the proportion of small-angle grain boundaries between 2° and 5° is 59.4%, with a flanging factor of 0.6.

[0040] Comparative Example 1

[0041] The composition of 6-series aluminum alloy is 0.55% Si, 0.64% Mg, 0.11% Cu, 0.19% Fe, 0.09% Mn, 0.006% Zn, 0.02% Ti, etc., with the balance being Al.

[0042] The casting is carried out according to the above composition, and the ingot is homogenized by a process of 550℃ for 10 hours.

[0043] After homogenization, the product is directly subjected to hot rolling at a starting temperature of 520℃.

[0044] Hot rolling adopts 1+5 rolling, the hot rolling coiling temperature is 310℃, and the coiling thickness is 5mm.

[0045] After hot rolling, the coil is uncoiled and cooled to 80°C on an uncoiler, and then cold rolled directly on a cold rolling mill.

[0046] After cold rolling, a solution treatment is performed at a temperature of 540℃ for 40 seconds.

[0047] After solution treatment, pre-aging is performed at a temperature of 90℃.

[0048] In Comparative Example 1, the distribution of small-angle grain boundaries is uneven, with small-angle grain boundaries of 2°-5° accounting for 40%, and the flanging factor is 0.75.

[0049] Comparative Example 2

[0050] The composition of 6-series aluminum alloy is Si 0.6%, Mg 0.68%, Cu 0.14%, Fe 0.21%, Mn 0.12%, Zn 0.008%, Ti 0.023%, etc., with the balance being Al.

[0051] The casting is carried out according to the above composition, and the ingot is homogenized by a process of 570℃ for 8 hours.

[0052] After homogenization, the product is directly subjected to hot rolling at a starting temperature of 510℃.

[0053] The hot rolling process uses a 1+5 rolling method, with a hot rolling coiling temperature of 400℃ and a coiling thickness of 2.5mm.

[0054] After being hot-rolled and coiled, the coils are cooled to room temperature and then cold-rolled on a cold rolling mill.

[0055] After cold rolling, a solution treatment is performed at a temperature of 520℃ and a holding time of 60s.

[0056] After solution treatment, pre-aging is performed at a temperature of 100℃.

[0057] In Comparative Example 2, the distribution of small-angle grain boundaries in the finished product is uneven, and the proportion of small-angle grain boundaries between 2° and 5° is 5.8%, with a flanging factor of 0.9.

[0058] The comparison of the test results of Example 1 and Comparative Examples 1-2 shows that the small-angle grain boundary distribution of the plate prepared by the present invention is relatively uniform, and the proportion of small-angle grain boundaries of 2°-5° and the flanging factor are far superior to those of Comparative Examples 1-2. Therefore, it can be widely promoted and applied.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the flangeability of a 6000-series aluminum alloy automotive panel, comprising: It comprises the following steps: ​ Step one: according to the aluminum alloy component, the raw material type is selected and smelting casting is carried out to obtain the ingot; Step two: the ingot is subjected to homogenization treatment; Step three: after the ingot is homogenized, hot rolling treatment is directly carried out; Step four: after the hot rolling and curling, the uncoiler is used to uncoil, realize rapid cooling, and the temperature is reduced to 70-80℃, then cold rolling is carried out until the target thickness is reached; Step five: after the cold rolling, solid solution treatment is carried out; Step six: after the solid solution treatment, pre-aging treatment is carried out to obtain the aluminum alloy plate; The component in step one is: Si 0.58%; Mg 0.6%; Cu 0.1%, Fe 0.2%; Mn 0.1%; Zn 0.007%; Ti 0.02%; the balance is Al; The small angle grain boundary of the aluminum alloy plate is in the range of 60%-70%, and the 2°-5° small angle grain boundary is in the range of 50%-60%.

2. The method according to claim 1, wherein the method for improving flangeability of 6000 series aluminum alloy automotive sheet is characterized by: The homogenization treatment temperature in step two is 550-580℃, and the time is 4-10h.

3. The method of claim 1, wherein the method is characterized by: The hot rolling treatment in step three is: the opening rolling temperature is 510-530℃, the rolling adopts 1+5 rolling, the hot rolling curling temperature is 310-400℃, and the curling thickness is 2.5-5mm.

4. The method of claim 1, wherein the method is characterized by: In step four, the cold rolling reduction is 60%-80% to ensure the surface quality.

5. The preparation method for improving the flanging performance of 6-series aluminum alloy automotive sheet metal according to claim 1, characterized in that: In step five, the solid solution temperature is 520-580℃, and the holding time is 20-60s.

6. The preparation method for improving the flanging performance of 6-series aluminum alloy automotive sheet metal according to claim 1, characterized in that: In step six, the pre-aging temperature is 70-100℃.

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