A 6-series aluminum alloy and a preparation method and application thereof

Abstract

The application discloses a 6-series aluminum alloy and a preparation method and application thereof. The 6-series aluminum alloy contains Si, Fe, Cu, Mn, Mg, Cr, Zn, Ti and Al. Through collocation and content control of the elements, the strengthening effect in the aging treatment process is effectively improved, beneficial adjustment of the organizational structure is realized in combination with the process, the intergranular corrosion depth is significantly reduced under the premise of guaranteeing the mechanical properties, and the application in preparation of industrial materials such as automobiles, rail vehicles and equipment components can be realized.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloys, specifically to a 6-series aluminum alloy, its preparation method, and its applications. Background Technology

[0002] 6061 aluminum alloy is a major alloy in the 6000 series of aluminum alloys. It possesses moderate strength and good plasticity, weldability, and cold workability, making it widely used in construction, transportation, and shipbuilding. In practical applications, it inevitably encounters high-temperature and high-humidity environments, such as the coolant in tram cooling systems. With the increasing prevalence of trams and the continuous upgrading of cooling systems and safety protection levels, resistance to intergranular corrosion is becoming increasingly important for 6061 aluminum alloy, in addition to its conventional mechanical properties. Intergranular corrosion is generally considered a type of localized corrosion that propagates inward along the interfaces between metal grains. It is mainly caused by differences in chemical composition between the grain surface and interior, as well as the presence of impurities or internal stress at grain boundaries. Intergranular corrosion destroys the bonding between grains, significantly reducing the mechanical strength of the metal. Furthermore, after corrosion occurs, the surface of the metal and alloy may still retain a certain metallic luster, showing no signs of damage, but the intergranular bonding force is significantly weakened, mechanical properties deteriorate, and it cannot withstand impacts, making it a very dangerous form of corrosion. The current 6061 aluminum alloy not only has insufficient resistance to intergranular corrosion, but also has difficulty in achieving a balance between mechanical strength and resistance to corrosion. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an improved 6-series aluminum alloy and its preparation method, which has excellent resistance to intergranular corrosion while ensuring good strength.

[0004] The present invention also provides an application of the above-mentioned 6-series aluminum alloy in the manufacture of vehicle and equipment components.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A method for preparing a 6-series aluminum alloy, the method comprising: (i) Forming an aluminum alloy body, wherein, by weight percentage, the 6-series aluminum alloy comprises: 0.68 wt.% to 0.75 wt.% Si; 0 to 0.15 wt.% Fe; 0.155 wt.% to 0.195 wt.% Cu; 0.1 wt.% to 0.14 wt.% of Mn; 0.85 wt.% to 0.95 wt.% Mg; 0.20 wt.% to 0.24 wt.% of Cr; 0 to 0.05 wt.% Zn; 0 to 0.10 wt.% Ti; The Al content was adjusted to achieve 100 wt.% for 6-series aluminum alloys. (ii) The aluminum alloy body is subjected to homogenization treatment, extrusion molding, online quenching, stress-relieving stretching and aging treatment; The aging process is controlled to be carried out at 170-180℃ and 200-210℃ respectively, and the aging time at 200-210℃ is controlled to be less than or equal to the aging time at 170-180℃.

[0006] According to some specific aspects of the present invention, the Si content in the 6-series aluminum alloy is 0.68 wt.%, 0.69 wt.%, 0.7 wt.%, 0.71 wt.%, 0.72 wt.%, 0.73 wt.%, 0.74 wt.%, 0.75 wt.%, etc., by weight percentage.

[0007] According to some specific aspects of the present invention, the Fe content in 6-series aluminum alloys can be 0.08 wt.%, 0.1 wt.%, 0.11 wt.%, 0.12 wt.%, 0.13 wt.%, 0.14 wt.%, 0.15 wt.%, etc., by weight percentage.

[0008] According to certain aspects of the present invention, the Cu content in the 6-series aluminum alloy, by weight percentage, is 0.155 wt.%, 0.158 wt.%, 0.16 wt.%, 0.162 wt.%, 0.165 wt.%, 0.168 wt.%, 0.17 wt.%, 0.172 wt.%, 0.175 wt.%, 0.178 wt.%, 0.180 wt.%, 0.182 wt.%, 0.185 wt.%, 0.188 wt.%, 0.19 wt.%, 0.192 wt.%, 0.194 wt.%, etc.

[0009] According to certain aspects of the present invention, the Mn content in 6-series aluminum alloys, by weight percentage, is 0.1 wt.%, 0.105 wt.%, 0.108 wt.%, 0.11 wt.%, 0.112 wt.%, 0.115 wt.%, 0.118 wt.%, 0.12 wt.%, 0.122 wt.%, 0.125 wt.%, 0.128 wt.%, 0.130 wt.%, 0.132 wt.%, 0.135 wt.%, 0.138 wt.%, 0.14 wt.%, etc.

[0010] According to certain aspects of the present invention, the Mg content in the 6-series aluminum alloy is 0.85 wt.%, 0.86 wt.%, 0.87 wt.%, 0.88 wt.%, 0.89 wt.%, 0.9 wt.%, 0.91 wt.%, 0.92 wt.%, 0.93 wt.%, 0.94 wt.%, 0.95 wt.%, etc., by weight percentage.

[0011] According to certain specific aspects of the present invention, the Cr content in the 6-series aluminum alloy, by weight percentage, is 0.20 wt.%, 0.202 wt.%, 0.205 wt.%, 0.208 wt.%, 0.21 wt.%, 0.212 wt.%, 0.215 wt.%, 0.218 wt.%, 0.22 wt.%, 0.222 wt.%, 0.225 wt.%, 0.228 wt.%, 0.23 wt.%, 0.232 wt.%, 0.235 wt.%, 0.238 wt.%, 0.24 wt.%, etc.

[0012] In some embodiments of the present invention, the mass ratio of Si, Fe and Cu content in the 6-series aluminum alloy is 1:0.15-0.19:0.22-0.29, and more specifically 1:0.16-0.18:0.235-0.28.

[0013] According to certain specific aspects of the present invention, the numerical range "0.15-0.19" in "1∶0.15-0.19∶0.22-0.29" can be 0.15, 0.152, 0.153, 0.154, 0.155, 0.158, 0.160, 0.161, 0.162, 0.163, 0.165, 0.166, 0.167, 0.168, 0.169, 0.170, 0.171, 0.172, 0.175, 0.178, 0.180, 0.182, 0.183, 0.185, etc.; the numerical range "0.22-0.29" can be 0. 0.22, 0.225, 0.23, 0.235, 0.238, 0.240, 0.241, 0.242, 0.243, 0.244, 0.245, 0.246, 0.248, 0.25, 0.252, 0.253, 0.254, 0.255, 0.258, 0.260, 0.261, 0.262, 0.263, 0.265, 0.266, 0.267, 0.268, 0.269, 0.270, 0.271, 0.272, 0.275, 0.278, 0.280, 0.282, 0.283, 0.285, etc.

[0014] In some embodiments of the present invention, the mass ratio of Mn content, Cr content and Ti content in the 6-series aluminum alloy is 1:1.55-2.0:0.35-0.9, and more specifically 1:1.6-1.9:0.35-0.75.

[0015] According to certain aspects of the present invention, the numerical range "1.55-2.0" in "1∶1.55-2.0∶0.35-0.9" can be 1.55, 1.58, 1.6, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69, 1.70, 1.71, 1.72, 1.73, 1.74, 1.7 5, 1.76, 1.78, 1.79, 1.8, 1.81, 1.82, 1.83, 1.84, 1.85, 1.86, 1.87, 1.88, 1.89, 1.90, 1.91, 1.92, 1.93, 1.94, 1.95, 1.96, 1.97, 1.98, 1.99, 2.0, etc.; the numerical range "0.35-0.9" can be 0.3. 5, 0.352, 0.353, 0.354, 0.355, 0.358, 0.360, 0.361, 0.362, 0.363, 0.365, 0.366, 0.367, 0.368, 0.369, 0.370, 0.371, 0.372, 0.375, 0.38, 0.39, 0.40, 0.41, 0.42, 0.44 0.45, 0.46, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.65, 0.66, 0.67, 0.68, 0.70, 0.72, 0.75, 0.78, 0.80, 0.85, etc.

[0016] In some embodiments of the present invention, the 6-series aluminum alloy comprises, by weight percentage: 0.68 wt.% to 0.74 wt.% Si; 0.08 wt.% to 0.15 wt.% Fe; 0.165 wt.% to 0.195 wt.% Cu; 0.11 wt.% to 0.14 wt.% of Mn; 0.85 wt.% to 0.95 wt.% Mg; Cr from 0.20 wt.% to 0.235 wt.%; 0 to 0.05 wt.% Zn; 0.04 wt.% to 0.10 wt.% Ti; The 6-series aluminum alloy was made to meet the 100 wt. requirement by adjusting the Al content.

[0017] In some embodiments of the present invention, the 6-series aluminum alloy comprises, by weight percentage: 0.70 wt.% to 0.73 wt.% Si; 0.1 wt.% to 0.15 wt.% Fe; 0.17 wt.% to 0.19 wt.% Cu; 0.115 wt.% to 0.14 wt.% of Mn; 0.85 wt.% to 0.95 wt.% Mg; Cr from 0.205 wt.% to 0.23 wt.%; 0 to 0.05 wt.% Zn; 0.05 wt.% to 0.085 wt.% Ti; The 6-series aluminum alloy was made to meet the 100 wt. requirement by adjusting the Al content.

[0018] In some embodiments of the present invention, the aging time at 170-180°C is 6-8 hours, and the aging time at 200-210°C is 2-6 hours.

[0019] The secondary aging treatment of the present invention is beneficial to further reduce the depth of intergranular corrosion and ensure mechanical properties. In particular, the formulation of the present invention, combined with the above-mentioned secondary aging treatment, can effectively broaden the range of aging time at the above-mentioned aging temperature, which is conducive to the smooth progress of the production process and improves the tolerance (avoiding the fact that the aging treatment of conventional aluminum alloy formulations only allows for fluctuations of about 0.5 hours, and once exceeded, performance will deteriorate).

[0020] In some embodiments of the present invention, in step (i), the aluminum alloy body is formed by casting at a temperature of 720-740°C.

[0021] In some embodiments of the present invention, step (ii) includes: heating the cast aluminum rod from room temperature to 560-570°C at a heating rate of 100-240°C / h, then holding it at that temperature for a time of 10 hours or more, and then cooling it at a cooling rate of 190°C or more to below 150°C.

[0022] Further, in step (ii), the homogenization process includes: heating the cast aluminum rod from room temperature to 560-570°C at a heating rate of 150-220°C / h, then holding it at that temperature for 10-20h, and then cooling it at a cooling rate of 190°C / h or higher to below 150°C.

[0023] In some embodiments of the present invention, in step (ii), the outlet temperature is controlled to be greater than or equal to 525°C and less than or equal to 550°C during the extrusion molding process.

[0024] According to some specific and preferred aspects of the present invention, in step (ii), during the extrusion molding process, the temperature of the aluminum rod on the extrusion press is 490-510°C, the temperature of the die is 480-490°C, the temperature of the extrusion cylinder is 410-430°C, the extrusion speed is 1.5-2.0 mm / s, and the temperature of the discharge port is 525-545°C.

[0025] In some embodiments of the present invention, in step (ii), during the online quenching process, the cooling rate is controlled to be above 5°C / s, and the profile is controlled to be cooled to below 60°C after passing through the quenching zone, with continuous cooling during the process.

[0026] In some embodiments of the present invention, in step (ii), the stress-relieving stretching is performed by straightening treatment, and the straightening stretching rate is controlled to be greater than or equal to 1%.

[0027] Furthermore, in step (ii), the stress-relieving stretching is performed by straightening treatment, and the straightening stretching rate is controlled at 1%-3%, for example, it can be 1%, 1.5%, 2.0%, 2.5%, 3.0%, etc.

[0028] In some embodiments of the present invention, in step (ii), the aging treatment is controlled to be performed within 8 hours after the stress-relief stretching.

[0029] Another technical solution provided by the present invention: a 6-series aluminum alloy prepared by the above-described method for preparing 6-series aluminum alloy.

[0030] In some embodiments of the present invention, the yield strength of the 6-series aluminum alloy is greater than or equal to 265 MPa, the tensile strength is greater than or equal to 285 MPa, the elongation is greater than or equal to 10%, and the intergranular corrosion depth is less than or equal to 10 μm.

[0031] According to some specific aspects of the present invention, the intergranular corrosion depth of the 6-series aluminum alloy can be less than or equal to 5 μm, or even less than or equal to 1 μm.

[0032] Another technical solution provided by the present invention: a 6-series aluminum alloy comprising, by weight percentage: 0.68 wt.% to 0.75 wt.% Si; 0 to 0.15 wt.% Fe; 0.155 wt.% to 0.195 wt.% Cu; 0.1 wt.% to 0.14 wt.% of Mn; 0.85 wt.% to 0.95 wt.% Mg; 0.20 wt.% to 0.24 wt.% of Cr; 0 to 0.05 wt.% Zn; 0 to 0.10 wt.% Ti; The Al content was adjusted to meet the 100 wt.% requirement for 6-series aluminum alloys. Another technical solution provided by the present invention: the application of the above-mentioned 6-series aluminum alloy in the manufacture of vehicles and mechanical components.

[0033] Due to the application of the above-mentioned technical solution, the present invention has the following advantages compared with the prior art: The formulation of this invention is easy to implement, and the elements are inexpensive and readily available. No special new elements are introduced to reduce intergranular corrosion and / or improve strength. The composition is highly clean, which is conducive to recycling. In particular, the 6-series aluminum alloy of this invention has extremely high resistance to intergranular corrosion while ensuring strength, overcoming the problem in the prior art that it is difficult to balance mechanical properties and intergranular corrosion resistance. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the intergranular corrosion cross-section of the aluminum alloy prepared in Example 1; Figure 2 This is a schematic diagram of the intergranular corrosion cross-section microstructure of the aluminum alloy prepared in Example 2; Figure 3 This is a schematic diagram of the intergranular corrosion cross-section of the aluminum alloy prepared in Example 3; Figure 4 This is a schematic diagram of the intergranular corrosion cross-section of the aluminum alloy prepared in Example 4; Figure 5 This is a schematic diagram of the intergranular corrosion cross-section of the aluminum alloy prepared in Example 5; Figure 6 This is a schematic diagram of the intergranular corrosion cross-section of the aluminum alloy prepared in Example 6; Figure 7 A schematic diagram of the intergranular corrosion cross-section microstructure of the aluminum alloy prepared in Example 7; Figure 8 This is a schematic diagram of the intergranular corrosion cross-section of the aluminum alloy prepared in Example 8; Figure 9A schematic diagram of the intergranular corrosion cross-section microstructure of the aluminum alloy prepared in Example 9; Figure 10 This is a schematic diagram of the intergranular corrosion cross-section of the aluminum alloy prepared in Comparative Example 1. Figure 11 This is a schematic diagram of the intergranular corrosion cross-section of the aluminum alloy prepared in Comparative Example 2. Figure 12 This is a schematic diagram of the intergranular corrosion cross-section of the aluminum alloy prepared in Comparative Example 3. Figure 13 This is a schematic diagram of the intergranular corrosion cross-section of the aluminum alloy prepared in Comparative Example 4. Figure 14 This is a schematic diagram of the intergranular corrosion cross-section of the aluminum alloy prepared in Comparative Example 5. Detailed Implementation

[0035] 6061 aluminum alloy is an Al-Mg-Si-Cu heat-treatable alloy. Analysis suggests that its intergranular corrosion is essentially caused by microcouples formed between the grain boundaries and the interior of the grains due to differences in microstructure, leading to preferential dissolution in the anodic region. Specifically: First, the electrochemical inhomogeneity caused by grain boundary precipitates results in the continuous precipitation of different second phases along the grain boundaries under different heat treatment states. Copper-rich phases (Al2Cu) have a more positive electrode potential than the surrounding aluminum matrix, forming microcathodes and making adjacent copper-poor regions microanodes, preferentially dissolving them, and allowing corrosion to extend deeper along the grain boundaries. Second, intergranular corrosion does not occur under arbitrary conditions; a continuous grain boundary precipitation network must be formed. During natural aging (T4), the grain boundaries have not yet formed harmful continuous phases, resulting in excellent resistance to intergranular corrosion. During peak aging (T6), the intragranular precipitation is fine and dispersed, but if the process control is inadequate, the precipitates can easily nucleate at the grain boundaries and grow into continuous chains. Furthermore, mismatched alloy composition and grain boundary characteristics significantly increase the risk of copper-rich cathode phases forming at grain boundaries. At the same time, when recrystallized grains are coarse and straight, precipitates are more likely to form a continuous network, providing continuous channels for corrosion and exacerbating intergranular corrosion.

[0036] Based on this, the present invention provides an improved 6-series aluminum alloy. By controlling the alloying elements and their relative contents, such as silicon, iron, and copper, the alloy's hot working and forming properties are improved while suppressing intergranular corrosion, while fully retaining the strengthening phases. Furthermore, controlling the contents of manganese, chromium, and titanium facilitates the formation of fine, dispersed phases in the aluminum, preventing recrystallization and growth of grains during hot working or heat treatment. This results in elongated fibrous grains rather than coarse equiaxed grains, breaking the continuous network structure of harmful phases and cutting off the rapid pathways for intergranular corrosion, thereby significantly reducing the tendency for intergranular corrosion. Simultaneously, a large number of nucleation sites are generated during solidification, resulting in fine and uniform grains. The formulation of this invention effectively reduces the concentrated segregation of impurities such as iron at grain boundaries during solidification, allowing harmful phases to be more dispersed, reducing enrichment at grain boundaries, and thus mitigating intergranular corrosion.

[0037] Furthermore, this invention effectively improves the strengthening effect during the aging process by controlling the combination and content of various elements. In addition, the process allows for controlled phase precipitation throughout the manufacturing process, ensuring that soluble phases are completely or nearly completely dissolved, forming a supersaturated solid solution and a small number of dispersed fine particles. Simultaneously, the spheroidized grain boundary precipitates significantly reduce the depth of intergranular corrosion while maintaining mechanical properties.

[0038] The method for preparing the 6-series aluminum alloy of the present invention includes: (1) Melting and casting: The raw materials are prepared using pure aluminum ingots, magnesium ingots, 50% aluminum-copper alloy (copper accounts for 50%), 20% aluminum-silicon alloy (silicon accounts for 20%), 10% aluminum-manganese alloy (manganese accounts for 10%), and 10% aluminum-chromium alloy (chromium accounts for 10%). Ti element is added during casting in the form of aluminum-titanium-boron wire. Semi-continuous DC casting is adopted, and the casting temperature is 720-740℃.

[0039] (2) Homogenization treatment The cast aluminum rod is heated from room temperature to 560-570℃ at a heating rate of 100-240℃ / h, then held at that temperature for at least 10 hours. It is then cooled to below 150℃ using a combination of forced air cooling and water cooling at a rate of at least 190℃ / h. Homogenization using this method yields smaller grains.

[0040] (3) Extrusion molding The homogenized long bars are extruded and formed, with the temperature of the aluminum bars on the extrusion machine controlled at 490-510℃, the temperature of the die at 480-490℃, the temperature of the extrusion cylinder at 410-430℃, the extrusion speed at 1.5-2.0mm / s, and the temperature of the discharge port at 525-545℃.

[0041] (4) Online quenching The extruded profiles are quenched online using air cooling or water cooling at a rate of ≥5℃ / s. After passing through the quenching zone, the profiles are cooled to below 60℃, and continuous cooling is required without interruption.

[0042] (5) Stress-relief stretching The straightening elongation rate of the profile strip after straightening is controlled at ≥1.0%, which is a stress-relief stretching process that completely removes stress.

[0043] (6) Timeliness processing Aging treatment should be carried out within 8 hours after stress relief stretching. The first stage is aging at 170-180℃ for 6-8 hours, and the second stage is aging at 200-210℃ for 2-6 hours.

[0044] In some embodiments, the 6-series aluminum alloys of the present invention may have the elemental composition shown in Table 1.

[0045] Table 1 The above-mentioned solution will be further described below with reference to specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0046] Unless otherwise specified in the following examples, all raw materials are commercially available or prepared by conventional methods in the art.

[0047] Examples 1-3: These embodiments provide 6-series aluminum alloys and their preparation methods, which have the elemental composition shown in Table 2.

[0048] Table 2 The remaining impurity elements are individually ≤0.05% and total <0.15%. Zn is a component naturally present in each raw material and was not actively added. The zinc in Example 3 is different from that in Example 1, which should be due to the difference in component content between different batches of raw materials.

[0049] The preparation methods for 6-series aluminum alloys include: (1) Melting and casting: The raw materials consist of pure aluminum ingots, magnesium ingots, and 50% aluminum-copper alloy; 20% aluminum-silicon alloy, 10% aluminum-manganese alloy, and 10% aluminum-chromium alloy. Ti element is added during casting in the form of aluminum-titanium-boron wire. Semi-continuous DC casting is adopted, and the casting temperature is 735±5℃.

[0050] (2) Homogenization treatment The cast aluminum rod was heated from room temperature to 565±5℃ at a heating rate of 200±5℃ / h, and then held at that temperature for 12 hours. It was then cooled to about 50℃ using a combination of forced air cooling and water cooling at a cooling rate of 200±5℃ / h.

[0051] (3) Extrusion molding The homogenized long bars are extruded and formed, with the temperature of the aluminum bars on the extrusion machine controlled at 500±10℃, the temperature of the die at 485±5℃, the temperature of the extrusion cylinder at 420±10℃, the extrusion speed at 1.7mm / s, and the temperature of the discharge port at 535±10℃.

[0052] (4) Online quenching The extruded profiles are quenched online using water cooling at a rate of 5°C / s. After passing through the quenching zone, the profiles are cooled to 60°C, and continuous cooling is required without interruption.

[0053] (5) Stress-relief stretching The straightening elongation rate of the profile strip is controlled at 1% after straightening, which is a stress-relief stretching process that completely removes stress.

[0054] (6) Timeliness processing Six hours after stress-relief stretching, aging treatment was carried out. The aging process consisted of first-stage treatment at 175℃ for 8 hours, followed by a 30-minute heating process at 175℃ to reach 200℃, and then second-stage treatment at 200℃ for 4 hours.

[0055] Example 4: This embodiment provides a 6-series aluminum alloy and its preparation method, which is basically the same as that in Embodiment 1, except that: in the aging process, the aging process is to treat at 175°C for 6 hours in the first stage, raise the temperature at 175°C for 30 minutes to reach 200°C, and treat at 200°C for 2 hours in the second stage.

[0056] Example 5: This embodiment provides a 6-series aluminum alloy and its preparation method, which is basically the same as that in Embodiment 1, except that: in the aging process, the aging process is to treat at 175°C for 8 hours in the first stage, raise the temperature at 175°C for 30 minutes to reach 200°C, and treat at 200°C for 2 hours in the second stage.

[0057] Example 6: This embodiment provides a 6-series aluminum alloy and its preparation method, which is basically the same as that in Embodiment 1, except that: in the aging process, the aging process is to treat at 175°C for 8 hours in the first stage, raise the temperature at 175°C for 30 minutes to reach 200°C, and treat at 200°C for 6 hours in the second stage.

[0058] Example 7: This example provides a 6-series aluminum alloy and its preparation method, which is basically the same as in Example 1, except that the temperature of the aluminum rod on the machine is 490±5℃.

[0059] Example 8: This example provides a 6-series aluminum alloy and its preparation method, which is basically the same as in Example 1, except that the outlet temperature is 500±5℃.

[0060] Example 9: This example provides a 6-series aluminum alloy and its preparation method, which is basically the same as in Example 1, except that: during the online quenching process, the profile is cooled to 150°C after passing through the quenching zone.

[0061] Comparative Examples 1-3: This example provides an aluminum alloy and its preparation method, which has the elemental composition shown in Table 3.

[0062] Table 3 The preparation method is the same as in Example 1.

[0063] Comparative Example 4: This example provides an aluminum alloy and its preparation method, which are basically the same as in Example 1, except that the aging process is carried out at 175°C for 12 hours.

[0064] Comparative Example 5: This example provides an aluminum alloy and its preparation method, which are basically the same as in Example 1, except that the aging process is carried out at 200°C for 8 hours.

[0065] Performance testing: The aluminum alloys obtained in Examples 1-9 and Comparative Examples 1-5 were subjected to the following performance tests, and the specific results are shown in Table 4. The test standard for tensile strength is GB / T 16865-2013 "Test Methods for Mechanical Properties of Wrought Aluminum Alloys and Sample Preparation Methods"; the test standard for yield strength is GB / T 16865-2013 "Test Methods for Mechanical Properties of Wrought Aluminum Alloys and Sample Preparation Methods"; the test standard for elongation is GB / T 16865-2013 "Test Methods for Mechanical Properties of Wrought Aluminum Alloys and Sample Preparation Methods"; and the test standard for intergranular corrosion is GB / T 7998-2023 "Evaluation Method for Intergranular Corrosion Sensitivity of Aluminum Alloys".

[0066] Table 4 Intergranular corrosion test diagrams of the aluminum alloys obtained in Examples 1-9 and Comparative Examples 1-5 are shown below. Figures 1 to 14 As shown.

[0067] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0068] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for preparing a 6-series aluminum alloy, characterized in that, The preparation method includes: (i) Forming an aluminum alloy body, wherein, by weight percentage, the 6-series aluminum alloy comprises: 0.68 wt.% to 0.75 wt.% Si; 0 to 0.15 wt.% Fe; 0.155 wt.% to 0.195 wt.% Cu; 0.1 wt.% to 0.14 wt.% of Mn; 0.85 wt.% to 0.95 wt.% Mg; 0.20 wt.% to 0.24 wt.% of Cr; 0 to 0.05 wt.% Zn; 0 to 0.10 wt.% Ti; The Al content was adjusted to meet the 100 wt.% requirement for 6-series aluminum alloys. (ii) The aluminum alloy body is subjected to homogenization treatment, extrusion molding, online quenching, stress-relieving stretching and aging treatment; The aging process is controlled to be carried out at 170-180℃ and 200-210℃ respectively, and the aging time at 200-210℃ is controlled to be less than or equal to the aging time at 170-180℃.

2. The method for preparing 6-series aluminum alloys according to claim 1, characterized in that, In 6-series aluminum alloys, the mass ratio of Si, Fe, and Cu content is 1:0.15-0.19:0.22-0.29, and further 1:0.16-0.18:0.235-0.

28.

3. The method for preparing 6-series aluminum alloys according to claim 1, characterized in that, In 6-series aluminum alloys, the mass ratio of Mn, Cr, and Ti is 1:1.55-2.0:0.35-0.9, and further 1:1.6-1.9:0.35-0.

75.

4. The method for preparing 6-series aluminum alloys according to claim 1, characterized in that, By weight percentage, 6-series aluminum alloys comprise: 0.69 wt.% to 0.74 wt.% Si; 0.08 wt.% to 0.15 wt.% Fe; 0.165 wt.% to 0.195 wt.% Cu; 0.11 wt.% to 0.14 wt.% of Mn; 0.85 wt.% to 0.95 wt.% Mg; Cr from 0.20 wt.% to 0.235 wt.%; 0 to 0.05 wt.% Zn; 0.04 wt.% to 0.10 wt.% Ti; The 6-series aluminum alloy was made to meet the 100 wt. requirement by adjusting the Al content.

5. The method for preparing 6-series aluminum alloys according to claim 1, characterized in that, The aging time is 6-8 hours when carried out at 170-180℃, and 2-6 hours when carried out at 200-210℃.

6. The method for preparing 6-series aluminum alloys according to claim 1, characterized in that, In step (i), the aluminum alloy body is formed by casting at a temperature of 720-740°C; and / or, in step (ii), the homogenization process includes: heating the cast aluminum rod from room temperature to 560-570°C at a heating rate of 100-240°C / h, holding it at that temperature for at least 10 hours, and then cooling it at a cooling rate of at least 190°C / h to below 150°C.

7. The method for preparing 6-series aluminum alloys according to claim 1, characterized in that, In step (ii), during the extrusion molding process, the outlet temperature is controlled to be greater than or equal to 525℃ and less than or equal to 550℃. Further, during the extrusion molding process, the aluminum rod temperature is 490-510℃, the die temperature is 480-490℃, the extrusion cylinder temperature is 410-430℃, the extrusion speed is 1.5-2.0 mm / s, and the outlet temperature is 525-545℃; and / or, In step (ii), during the online quenching process, the cooling rate is controlled at 5℃ / s or higher, and the profile is controlled to cool to below 60℃ after passing through the quenching zone, with continuous cooling during this period; and / or, In step (ii), the stress-relieving stretching is performed using a straightening process, controlling the straightening stretching ratio to be greater than or equal to 1%; and / or, In step (ii), the aging treatment is controlled to be carried out within 8 hours after the stress-relief stretching.

8. A 6-series aluminum alloy prepared by the preparation method of the 6-series aluminum alloy according to any one of claims 1-7, wherein the 6-series aluminum alloy has a yield strength greater than or equal to 265 MPa, a tensile strength greater than or equal to 285 MPa, an elongation greater than or equal to 10%, and an intergranular corrosion depth less than or equal to 10 μm.

9. A 6-series aluminum alloy, characterized in that, By weight percentage, this 6-series aluminum alloy comprises: 0.68 wt.% to 0.75 wt.% Si; 0 to 0.15 wt.% Fe; 0.155 wt.% to 0.195 wt.% Cu; 0.1 wt.% to 0.14 wt.% of Mn; 0.85 wt.% to 0.95 wt.% Mg; 0.20 wt.% to 0.24 wt.% of Cr; 0 to 0.05 wt.% Zn; 0 to 0.10 wt.% Ti; The 6-series aluminum alloy was made to meet the 100 wt. requirement by adjusting the Al content.

10. The application of the 6-series aluminum alloy of claim 8 or the 6-series aluminum alloy of claim 9 in the manufacture of vehicle and equipment components.

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