A 6-series aluminum alloy profile and a processing method and application thereof

Abstract

This invention belongs to the field of alloy technology, and more specifically relates to a 6-series aluminum alloy profile, its processing method, and its application. The first aspect of this invention provides a 6-series aluminum alloy profile, the raw materials of which, by mass percentage, comprise the following components: Si: 0.4-0.8%, Fe: 0-0.7%, Cu: 0.15-0.4%, Mn: 0-0.15%, Mg: 0.8-1.2%, Cr: 0.04-0.35%, Zn: 0-0.25%, Ti: 0-0.15%, La: 0.05-0.2%, with the balance being Al and unavoidable impurities. The 6-series aluminum alloy profile provided by this invention, through strict control of the Mg-Si-La-Cr synergistic relationship, achieves a yield strength ≥266MPa, elongation ≥11.3%, and coarse grain layer ratio ≤18.7%, completely solving the industry problem of the traditional 6061 alloy's inability to simultaneously achieve high strength and high toughness, thus meeting the dual requirements of high strength and high plasticity for automotive battery trays.

Description

Technical Field

[0001] This invention belongs to the field of alloy technology, and more specifically relates to a 6-series aluminum alloy profile, its processing method, and its application. Background Technology

[0002] With the development of lightweighting in automobiles, aluminum alloy profiles are increasingly used in automotive parts due to their weight reduction advantages over steel. To maximize these weight reduction advantages, aluminum alloy profiles are required to have increasingly complex structures with more and more weight-reducing cavities, while simultaneously maintaining excellent mechanical properties, good toughness, fatigue resistance, corrosion resistance, and good extrusion efficiency. However, conventional 6061 aluminum alloys, when producing multi-cavity aluminum alloy profiles, struggle to simultaneously achieve optimal mechanical properties, extrusion efficiency, and optimal grain size and coarse grain layer.

[0003] In response to the problems existing in the current technology, there is an urgent need to develop a 6-series aluminum alloy material with excellent performance that can balance mechanical properties, extrusion efficiency, and grain size and coarse grain layer of the profile. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a 6-series aluminum alloy profile, its processing method and application, which solves the problem that it is difficult to balance mechanical properties, grain size, coarse grain layer and production cost in the prior art.

[0005] The first aspect of the present invention provides a 6-series aluminum alloy profile, wherein the raw material comprises the following components by mass percentage: Si: 0.4-0.8%, Fe: 0-0.7%, Cu: 0.15-0.4%, Mn: 0-0.15%, Mg: 0.8-1.2%, Cr: 0.04-0.35%, Zn: 0-0.25%, Ti: 0-0.15%, La 0.05-0.2%, with the balance being Al and unavoidable impurities.

[0006] The contents of Mg, Si, La, and Cr satisfy the following relationship: 1.2≤0.5ωMg+1.0ωSi+10ωLa×ωCr≤1.6 where ωMg, ωSi, ωLa, and ωCr are the mass percentages of Mg, Si, La, and Cr, respectively.

[0007] This invention significantly improves the overall performance and production efficiency of 6-series aluminum alloy profiles by precisely controlling the synergistic relationship of Mg, Si, La, and Cr elements. The linear combination of Mg and Si ensures a reasonable precipitation amount of the Mg2Si strengthening phase, avoiding brittleness caused by excessive Mg or strength loss due to insufficient Si. Through extensive creative research, the inventors discovered that the product relationship between La and Cr in this system synergistically inhibits grain boundary migration and recrystallization. La forms fine and dispersed LaAl3 compounds with Al, while Cr forms the AlCr2 phase, significantly refining the grains and inhibiting the formation of coarse grain layers. This synergistic effect ensures uniform deformation of the alloy during extrusion, preventing internal cracking. Simultaneously, by optimizing the precipitate distribution, it significantly improves the elongation and yield strength of the alloy profiles, perfectly solving the industry problem of the traditional 6061 aluminum alloy's inability to achieve both high strength and high efficiency. This provides an ideal material solution for complex structural components such as lightweight automotive battery trays.

[0008] In some alternative embodiments, the 6-series aluminum alloy profile raw material comprises the following components by mass percentage: Si: 0.6-0.8%, Fe: 0.1-0.5%, Cu: 0.15-0.3%, Mn: 0.09-0.15%, Mg: 0.8-0.98%, Cr: 0.1-0.2%, Zn: 0.05-0.15%, Ti: 0.1-0.15%, La 0.05-0.2%, with the balance being Al and unavoidable impurities.

[0009] In some alternative embodiments, the contents of Mn and Cr satisfy the following relationship: 0.05≤ωCr-0.5×ωMn≤0.12, where ωCr and ωMn are the mass percentages of Cr and Mn, respectively.

[0010] This invention significantly optimizes the microstructure and mechanical properties of 6-series aluminum alloy profiles by precisely controlling the synergistic relationship between Mn and Cr. Mn and Cr together form an Al6(Mn,Cr) composite precipitate. This synergistic effect stems from the "structural modification" effect of Cr on the Mn precipitate. An appropriate amount of Cr can refine the morphology of the Al6(Mn,Fe) phase, while Mn inhibits excessive segregation of Cr. The two are precisely balanced by a linear combination with a weight of 0.5, which balances the thermodynamic stability and kinetic diffusion rate of the precipitate. This provides a three-in-one material solution of "high strength, high toughness, and high efficiency" for complex structural components such as automotive battery trays. When ωCr - 0.5 × ωMn < 0.05, the amount of precipitated phase is insufficient and coarse, grain boundary migration is out of control, resulting in a grain size of only grade 1, a coarse grain layer ratio as high as 45.3%, and a yield strength as low as 231 MPa. When ωCr - 0.5 × ωMn > 0.12, excess Cr causes AlCr2 phase to aggregate, forming a stress concentration source, the grain size drops to grade 2, and the coarse grain layer ratio increases to 37.2%. However, when this value is strictly within the range of 0.10-0.12, the Al6(Mn,Cr) phase is uniformly dispersed at the nanoscale, effectively pinning grain boundaries and inhibiting recrystallization, stabilizing the grain size at grade 5-9, controlling the coarse grain layer ratio at 11.2%-18.7%, and achieving a yield strength ≥ 266 MPa and an elongation ≥ 11.3%.

[0011] A second aspect of the present invention provides a method for processing 6-series aluminum alloy profiles, comprising the following steps: S1: Melt and cast the 6-series aluminum alloy profile raw material to obtain an aluminum alloy ingot; S2: The aluminum alloy ingot is heated from room temperature to 440-490℃ at a heating rate of 50-200℃ / h, held at that temperature for 8-20h, and then cooled to <60℃ to obtain an aluminum alloy rod. S3: The aluminum alloy casting rod is placed into an extrusion device and extruded through a die to obtain a profile; S4: The profile is sequentially subjected to online quenching, straightening and sawing, and aging treatment to obtain the 6-series aluminum alloy profile.

[0012] Optionally, the heating rate mentioned in S2 can be 50℃ / h, 60℃ / h, 70℃ / h, 90℃ / h, 120℃ / h, 150℃ / h, 160℃ / h, 180℃ / h, 200℃ / h, etc., or any point value within the range of 50-200℃ / h, without further limitation here.

[0013] Optionally, the temperature in S2 is raised to 450-490℃. For example, it can be 450℃, 455℃, 460℃, 465℃, 470℃, 475℃, 480℃, 485℃, 490℃, etc. Of course, it can also be any point value within the range of 450-490℃, without further limitation here.

[0014] Optionally, the heat preservation time in S2 can be 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, etc., or any value within the range of 8-20h, without further limitation here.

[0015] In some optional embodiments, the cooling rate described in S2 is 4~10℃ / s; as an example, the cooling rate can be 4℃ / s, 5℃ / s, 6℃ / s, 7℃ / s, 8℃ / s, 9℃ / s, 10℃ / s, etc., or any value within the above range, without further limitation.

[0016] In some optional embodiments, the extrusion speed described in S3 is 1.5~2 mm / s; as an example, the extrusion speed can be 1.5 mm / s, 1.6 mm / s, 1.7 mm / s, 1.8 mm / s, 1.9 mm / s, 2.0 mm / s, etc., or any value within the above range, without further limitation here.

[0017] In some optional embodiments, the extrusion temperature conditions described in S3 are as follows: the aluminum alloy casting rod head temperature is 480-520°C, the aluminum alloy casting rod tail temperature is 450-470°C, the die temperature is 470-510°C, and the profile exit temperature is 490-530°C. As an example, the aluminum alloy casting rod head temperature can be any value within the range of 480°C, 490°C, 500°C, 510°C, 520°C, etc.; the aluminum alloy casting rod tail temperature can be any value within the range of 450°C, 460°C, 470°C, etc.; the die temperature can be any value within the range of 470°C, 480°C, 485°C, 490°C, 495°C, 500°C, 505°C, 510°C, etc.; and the profile exit temperature can be any value within the range of 490°C, 500°C, 510°C, 520°C, 530°C, etc.

[0018] It should be noted that in this invention, the mold in S3 is a multi-cavity battery casing frame.

[0019] For the processing of complex multi-cavity battery casing frame aluminum alloy profiles, the conventional extrusion speed can only reach 1.2 mm / s. Through the improvement of the composition and optimization of the content of the 6-series aluminum alloy profile raw material in this invention, especially the synergistic effect of Mg, Si, La, and Cr elements and the synergistic effect of Cr and Mn elements, the stability of the extrusion process is significantly improved. The temperature gradient control at the head and tail ensures that the 6-series aluminum alloy profile raw material deforms uniformly during the extrusion process, avoiding local stress concentration. Matching the die temperature and the exit temperature maintains the 6-series aluminum alloy profile raw material within the recrystallization temperature range, promoting dynamic recrystallization. When the extrusion bar speed is increased to 1.7 mm / s, the deformation heat and cooling rate are balanced, which avoids overheating that leads to grain coarsening, while ensuring sufficient deformation rate to refine the grains. This ensures that there is no tearing in the multi-cavity components, making it possible to use it in complex structural parts such as lightweight automotive battery trays.

[0020] In some alternative implementations, the online quenching described in S4 includes at least one of air cooling or water cooling.

[0021] Further optionally, the air cooling includes forced air cooling.

[0022] Further optionally, the water cooling includes at least one of water mist cooling, spray cooling, or water-through cooling.

[0023] In some optional implementations, the aging treatment conditions described in S4 are: a temperature of 160-200℃ and a holding time of 6-12h; as an example, the aging treatment temperature can be 160℃, 170℃, 180℃, 190℃, 200℃, etc., or any value within the above range; the aging treatment time can be 6h, 7h, 8h, 9h, 10h, 11h, 12h, etc., or any value within the above range.

[0024] A third aspect of the present invention provides an application of a 6-series aluminum alloy profile in an automotive battery tray.

[0025] Beneficial effects: The 6-series aluminum alloy profiles, their processing methods, and applications provided by this invention have the following advantages: (1) The 6-series aluminum alloy profile provided by the present invention, by strictly controlling the Mg-Si-La-Cr synergistic relationship, has a yield strength ≥266MPa, elongation ≥11.3%, and coarse grain layer ratio ≤18.7%, which completely solves the industry problem of "high strength and high toughness cannot be obtained at the same time" of traditional 6061 alloy, and meets the dual requirements of high strength and high plasticity for automotive battery trays.

[0026] (2) The 6-series aluminum alloy profile provided by the present invention, through the precise matching of the Mn-Cr synergistic relationship and the extrusion temperature gradient, increases the extrusion bar speed from the conventional 1.2 mm / s to 1.7 mm / s, significantly improving production efficiency, while avoiding internal cavity tearing caused by excessive speed, thus achieving "high efficiency-high quality" simultaneously.

[0027] (3) The present invention provides 6-series aluminum alloy profiles and their processing methods. Through the synergistic optimization of the raw material composition relationship and the process parameters during processing, the internal cavity tearing defects are completely eliminated, ensuring the structural integrity of the complex cross-section profile of the multi-cavity battery shell frame, and providing technical support for high-precision manufacturing.

[0028] (4) The optimized elongation of the 6-series aluminum alloy profile provided by the present invention is ≥11%, which significantly improves the impact resistance and fatigue life, meets the long-term reliability requirements of the battery tray under vibration and humid heat environment, and extends the service life of the whole vehicle. Attached Figure Description

[0029] Figure 1 The grain morphology images of sampling points 1 to 4 of the aluminum alloy profile product prepared in Example 2 are shown.

[0030] Figure 2 The grain morphology images of sampling points 5 to 8 of the aluminum alloy profile product prepared in Example 2 are shown.

[0031] Figure 3 This is a coarse grain morphology image of sampling point 1 of the aluminum alloy profile product prepared in Example 2.

[0032] Figure 4 This is a coarse grain morphology image of sampling point 2 of the aluminum alloy profile product prepared in Example 2.

[0033] Figure 5 This is a coarse grain morphology image of sampling point 3 of the aluminum alloy profile product prepared in Example 2.

[0034] Figure 6 This is a coarse grain morphology image of sampling point 4 of the aluminum alloy profile product prepared in Example 2.

[0035] Figure 7 This is a coarse grain morphology image of sampling point 5 of the aluminum alloy profile product prepared in Example 2.

[0036] Figure 8 This is a coarse grain morphology image of sampling point 6 of the aluminum alloy profile product prepared in Example 2.

[0037] Figure 9 This is a coarse grain morphology image of sampling point 7 of the aluminum alloy profile product prepared in Example 2.

[0038] Figure 10 This is a coarse grain morphology image of sampling point 8 of the aluminum alloy profile product prepared in Example 2.

[0039] Figure 11 The aluminum alloy profile (aluminum alloy frame of multi-cavity battery shell) product prepared in Example 2; the numbers 1 to 8 in the figure represent 8 random sampling points on the surface of the product; specifically, 1-sample 1; 2-sampling point 2; 3-sampling point 3; 4-sampling point 4; 5-sampling point 5; 6-sampling point 6; 7-sampling point 7; 8-sampling point 8. Detailed Implementation

[0040] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0041] Examples 1 to Comparative Examples 4 The first aspect of Examples 1 to Comparative Examples 4 provides a 6-series aluminum alloy profile. The raw materials of the 6-series aluminum alloy profile are shown in Table 1 below by mass percentage.

[0042] Table 1. Raw material composition of 6-series aluminum alloy profiles in the examples and comparative examples

[0043] The second aspect of Example 1 provides a method for processing 6-series aluminum alloy profiles, comprising the following steps: S1: Aluminum alloy ingots are obtained by melting and casting the raw materials of 6-series aluminum alloy profiles in Table 1; S2: The aluminum alloy ingot is heated from room temperature to 450°C at a heating rate of 160°C / h, held at that temperature for 12h, and then cooled to room temperature at a cooling rate of 300°C / h to obtain an aluminum alloy casting rod. S3: The aluminum alloy casting rod is placed into the extrusion equipment. The temperature of the aluminum alloy casting rod head is 490℃, the temperature of the aluminum alloy casting rod tail is 470℃, the die temperature is 505℃, the extrusion speed is 1.5mm / s, and the profile is obtained by extrusion through the die. The profile outlet temperature is 510-520℃. S4: The profile is sequentially subjected to online quenching, straightening and sawing, and aging treatment to obtain the 6-series aluminum alloy profile, specifically including: S41: Online quenching, using strong air cooling at a rate of 220℃ / min, cooling to room temperature; S42: Straightening sawing; S43: Aging treatment: Aging temperature 180℃, aging holding time 6h.

[0044] The 6-series aluminum alloy profile was obtained.

[0045] The processing method for the 6-series aluminum alloy profile provided in Example 2 is the same as that in Example 1, except that the extrusion speed in S3 is 1.7 mm / s. A schematic diagram of the alloy profile obtained in Example 2 is shown below. Figure 11 .

[0046] The processing method for the 6-series aluminum alloy profiles provided in Example 3 is the same as that in Example 2.

[0047] The processing method of the 6-series aluminum alloy profile provided in Comparative Example 1 is the same as that in Example 1. The 6-series aluminum alloy profile is processed according to the raw materials in Table 1, and the extrusion bar speed is 1.2 mm / s.

[0048] The processing methods for the 6-series aluminum alloy profiles provided in Comparative Examples 2 and 3 are the same as those in Example 1.

[0049] The processing method of the 6-series aluminum alloy profile provided in Comparative Example 4 is the same as that in Example 1. The difference from Example 1 is that the extrusion speed is 1.0 mm / s. Under the alloy settings of Comparative Example 4, the extrusion speed can only be 1.0 mm / s.

[0050] Performance testing The 6-series aluminum alloy profiles prepared in the above embodiments and comparative examples were tested, and the specific test results are shown in Table 2.

[0051] 1. Mechanical property testing: The test method refers to GB / T 228.1-2021; 2. Elongation test: The test method refers to GB / T 228.1-2021; 3. Grain size test: The test method refers to GB / T 3246.1-2024; 4. Coarse grain layer test: The test method refers to GB / 3246.2-2012; Table 2: Test Results of 6 Series Aluminum Alloy Profiles

[0052] As can be seen from the data in Table 2, by strictly controlling the Mg-Si-La-Cr synergistic relationship, the yield strength is ≥266MPa, the elongation is ≥11.3%, and the coarse grain layer ratio is ≤18.7%, which completely solves the industry problem of "high strength and high toughness being mutually exclusive" of the traditional 6061 alloy and meets the dual requirements of high strength and high plasticity for automotive battery trays.

[0053] And from Figure 1 and Figure 2As can be seen from the results, the alloy profile prepared in Example 2 has a high grain size level, and the grain size test results at each sampling point are consistent. from Figures 3-10 It can be seen that the coarse grain layer of the alloy profile prepared in Example 2 is significantly thinner and more uniformly distributed.

[0054] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0055] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A 6-series aluminum alloy profile, characterized in that, The raw materials comprise the following components by weight percentage: Si: 0.6-0.8%, Fe: 0.1-0.5%, Cu: 0.15-0.3%, Mn: 0.09-0.15%, Mg: 0.8-0.98%, Cr: 0.1-0.2%, Zn: 0.05-0.15%, Ti: 0.1-0.15%, La 0.05-0.2%, balance being Al and unavoidable impurities; The contents of Mg, Si, La, and Cr satisfy the following relationship: 1.2≤0.5ωMg+1.0ωSi+10ωLa×ωCr≤1.6, where ωMg, ωSi, ωLa, and ωCr are the mass percentages of Mg, Si, La, and Cr, respectively.

2. The 6-series aluminum alloy profile according to claim 1, characterized in that, The contents of Mn and Cr satisfy the following relationship: 0.05≤ωCr-0.5×ωMn≤0.12, where ωCr and ωMn are the mass percentages of Cr and Mn, respectively.

3. A method for processing 6-series aluminum alloy profiles according to claim 1 or 2, characterized in that, Includes the following steps: S1: Melt and cast 6-series aluminum alloy profile raw materials to obtain aluminum alloy ingots; S2: The aluminum alloy ingot is heated from room temperature to 440-490℃ at a heating rate of 50-200℃ / h, held at that temperature for 8-20h, and then cooled to <60℃ to obtain an aluminum alloy rod. S3: The aluminum alloy casting rod is placed into an extrusion device and extruded through a die to obtain a profile; S4: The profile is sequentially subjected to online quenching, straightening and sawing, and aging treatment to obtain the 6-series aluminum alloy profile.

4. The processing method for 6-series aluminum alloy profiles according to claim 3, characterized in that, The cooling rate described in S2 is 4~10℃ / s.

5. The processing method for 6-series aluminum alloy profiles according to claim 3, characterized in that, The extrusion speed described in S3 is 1.5~2 mm / s.

6. The processing method for 6-series aluminum alloy profiles according to claim 3, characterized in that, The extrusion temperature conditions described in S3 are as follows: the head temperature of the aluminum alloy casting rod is 480-520℃, the tail temperature of the aluminum alloy casting rod is 450-470℃, the die temperature is 470-500℃, and the profile exit temperature is 490-530℃.

7. The processing method for 6-series aluminum alloy profiles according to claim 3, characterized in that, The online quenching described in S4 includes at least one of air cooling or water cooling.

8. The processing method for 6-series aluminum alloy profiles according to claim 3, characterized in that, The aging treatment conditions described in S4 are: temperature of 160-200℃ and holding time of 6-12h.

9. An application of the 6-series aluminum alloy profile according to claim 1 or 2, characterized in that, Used in automotive battery trays.

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