Processing method for optimizing mechanical property of 6xxx aluminum alloy based on regulation and control of parking time

Abstract

The invention relates to the technical field of aluminum alloy material processing and heat treatment, in particular to a processing method for optimizing the mechanical property of 6xxx aluminum alloy based on parking time regulation, which comprises the following steps: preparing 6xxx aluminum alloy raw materials in percentage by mass: 0.4%-1.2% of Mg, 0.2%-0.8% of Si, 0.05%-0.3% of Cu, 0.05%-0.2% of Mn, 0.01%-0.1% of Cr, less than or equal to 0.35% of Fe, less than or equal to 0.1% of Zn and the balance of Al and inevitable trace impurities; according to the method, the parking time is improved from a passive variable neglected in a traditional process to a key controllable parameter cooperatively linked with alloy components and a heat treatment process, the performance fluctuation between product batches is greatly reduced by precisely controlling the parking conditions, the consistency and reliability of products are remarkably improved, and the product quality is improved. And a stable guarantee is provided for subsequent assembly and use.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy material processing and heat treatment technology, specifically to a processing method for optimizing the mechanical properties of 6xxx aluminum alloys based on adjusting the dwell time. Background Technology

[0002] 6xxx series aluminum alloys belong to the Al-Mg-Si alloy system. With their good formability, excellent corrosion resistance, and moderate mechanical strength, they have been widely used in various industrial fields such as automobile manufacturing, shipbuilding, construction engineering, and aerospace. Their traditional strengthening heat treatment process mainly includes three core steps: solution treatment, quenching, and artificial aging. While this process can meet basic usage requirements, many problems still need to be solved in actual production.

[0003] After solution quenching, the alloy is in a thermodynamically unstable state. During room temperature storage or natural aging, atomic clusters and GP zones spontaneously nucleate and grow. This dynamic change in microstructure directly affects the precipitation behavior and distribution of strengthening phases in the subsequent artificial aging stage; this phenomenon is known as the storage effect. In existing technologies, most production processes treat the storage stage as a passive waiting process, failing to precisely control the storage time. This leads to significant fluctuations in key mechanical properties between different batches, and even within the same batch, severely impacting assembly accuracy and reliability. In some 6xxx alloys, excessively long storage times result in the formation of stable and coarse atomic clusters, inhibiting the uniform precipitation of strengthening phases during subsequent artificial aging, leading to significant storage softening and a final strength far below the theoretical peak. Furthermore, existing technologies lack a systematic and collaborative design approach, merely adjusting solution temperature, aging parameters, or alloy composition without establishing an organic link between storage time, composition, and heat treatment processes, making it difficult to achieve an optimal balance between strength and plasticity. Furthermore, 6xxx aluminum alloys produced using traditional processes often fail to simultaneously meet the comprehensive requirements of high strength, high ductility, and excellent corrosion resistance, significantly limiting their application in fields with stringent material performance requirements, such as high-end equipment manufacturing. Even when some technologies mention the impact of storage time, they are limited to qualitative descriptions without clearly quantifying the control range, and they fail to design suitable storage schemes based on differences in alloy composition. As a result, existing technologies have consistently failed to overcome performance bottlenecks and generally suffer from high costs and complex processes. Summary of the Invention

[0004] The primary objective of this invention is to provide a processing method for optimizing the mechanical properties of 6xxx aluminum alloys based on adjusting the dwell time.

[0005] A further objective of this invention is to provide a processing method for optimizing the mechanical properties of 6xxx aluminum alloys based on controlling the dwell time, comprising the following steps:

[0006] (1) Prepare 6xxx aluminum alloy raw materials, wherein the mass percentage of the raw materials is: Mg 0.4%-1.2%, Si 0.2%-0.8%, Cu 0.05%-0.3%, Mn 0.05%-0.2%, Cr 0.01%-0.1%, Fe≤0.35%, Zn≤0.1%, and the remainder is Al and unavoidable trace impurities;

[0007] (2) Solution treatment: Place the aluminum alloy workpiece in a heating furnace, heat it to 530℃-580℃, and hold it for 10 minutes to 8 hours;

[0008] (3) Rapid quenching: After solution treatment, the workpiece is rapidly cooled at a rate of not less than 100℃ / min;

[0009] (4) Controllable storage: Place the quenched workpiece in a room temperature environment of 15℃-30℃ for 4 hours-72 hours, and keep the ambient temperature and humidity stable during the storage period; (5) Artificial aging: Place the stored workpiece in an aging furnace, heat it to 160℃-185℃, keep it at that temperature for 1 hour-10 hours, and then cool it to room temperature with the furnace.

[0010] Preferably, the raw material contains 0.6%-1.1% Mg and 0.4%-0.7% Si.

[0011] Preferably, the heating rate for the solution treatment is 5°C / min.

[0012] Preferably, the cooling method for rapid quenching is water quenching, water mist quenching, or a composite cooling method combining surface water mist quenching and core water quenching.

[0013] Preferably, the humidity of the controlled parking environment is 45%-55%.

[0014] Preferably, the artificial aging process adopts a segmented heating and heat preservation method, first heating to 160℃-165℃ and holding for 2-3 hours, then heating to 175℃-185℃ and holding for 3-4 hours.

[0015] Preferably, the Cu content in the raw material is 0.15%-0.28%.

[0016] Preferably, the heat treatment time is adjusted according to the workpiece thickness. When the workpiece thickness is 10mm-20mm, the heat treatment time is 60 minutes-120 minutes.

[0017] Preferably, the cooling rate for rapid quenching is 120℃ / min-170℃ / min.

[0018] Preferably, the controllable parking time is 6 hours to 60 hours.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. This invention elevates the storage time from a passive variable neglected in traditional processes to a key controllable parameter that works in conjunction with alloy composition and heat treatment processes. By precisely controlling storage conditions, it significantly reduces performance fluctuations between product batches, substantially improves product consistency and reliability, and provides a stable guarantee for subsequent assembly and use.

[0021] 2. This invention designs suitable storage time windows for different alloy compositions, effectively utilizes the beneficial precursors formed during the storage effect, promotes the uniform and fine precipitation of the strengthening phase, successfully breaks through the technical bottleneck of mutual constraint between strength and plasticity in traditional processes, achieves a good balance between high strength and high plasticity, and significantly improves the comprehensive mechanical properties of the material.

[0022] 3. By adjusting the relationship between the storage time and the alloy composition and process parameters, this invention can control the balance ratio of material strength and plasticity within a wide range, accurately meeting the differentiated performance requirements of different application scenarios such as high impact-resistant structural parts and high formability components, and significantly expanding the application range of 6xxx aluminum alloys.

[0023] 4. This invention does not require the addition of expensive alloying elements or the introduction of complex special equipment. It can achieve a significant leap in material performance simply by accurately managing the time in the production process and adapting the process parameters, which greatly reduces production costs and makes it more suitable for large-scale industrial production. It has extremely strong industrial promotion value.

[0024] 5. The synergistic regulation system of the present invention not only optimizes mechanical properties, but also improves the microstructure of the alloy, which significantly enhances the product's resistance to intergranular corrosion and exfoliation corrosion, effectively expanding the application scenarios of the material in corrosive environments such as marine environments and humid working conditions, and further enhancing the product's market competitiveness. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0026] Example 1:

[0027] (1) Alloy composition (mass percentage): Mg 0.6%, Si 0.4%, Fe 0.2%, Zn 0.05%, Al 98.75%;

[0028] (2) Processing steps:

[0029] Solution treatment: The aluminum alloy ingot is processed into a 10mm thick plate, placed in a heating furnace, heated to 550℃ at 5℃ / min, and held for 60 minutes;

[0030] Rapid quenching: Water quenching is performed immediately after removal, with a cooling rate of 150℃ / min;

[0031] Controlled storage: Place in an environment of 25℃ and 50% humidity for 6 hours;

[0032] Artificial aging: Heat to 170℃ at 3℃ / min, hold for 4 hours, and then cool to room temperature with the furnace.

[0033] Example 2:

[0034] (1) Alloy composition (mass percentage): Mg 0.9%, Si 0.6%, Fe 0.25%, Zn 0.06%, Al 98.19%; Based on the basic composition framework of Example 1, the Mg / Si ratio was adjusted to 1.5:1 to enhance the driving force for the precipitation of strengthening phase;

[0035] (2) Processing steps:

[0036] Solution treatment: Using a 10mm thick plate of the same specifications as in Example 1, the temperature was increased to 560℃ at 5℃ / min and held for 70 minutes;

[0037] Rapid quenching: Water mist quenching is used for cooling, with a cooling rate of 120℃ / min;

[0038] Controlled storage: Place in an environment of 23℃ and 45% humidity for 24 hours;

[0039] Artificial aging: Heat to 175℃ at 3℃ / min, hold for 5 hours, and then cool to room temperature with the furnace.

[0040] Example 3:

[0041] (1) Alloy composition (mass percentage): Mg 0.8%, Si 0.5%, Cu 0.2%, Fe 0.22%, Zn 0.05%, Al 98.23%; Based on the composition of Example 2, a trace amount of Cu was added to enhance the strengthening effect and corrosion resistance in conjunction with Mg and Si;

[0042] (2) Processing steps:

[0043] Solution treatment: Adjust the thickness of the board to 15mm, heat to 570℃ at 5℃ / min, and hold for 90 minutes;

[0044] Rapid quenching: Water quenching is used for cooling, with a cooling rate of 160℃ / min;

[0045] Controlled storage: Place in an environment of 27℃ and 55% humidity for 60 hours;

[0046] Artificial aging: Heat to 165℃ at 3℃ / min and hold for 2 hours, then heat to 180℃ and hold for 3 hours, then cool to room temperature with the furnace.

[0047] Example 4:

[0048] (1) Alloy composition (mass percentage): Mg 0.7%, Si 0.45%, Cu 0.15%, Mn 0.1%, Cr 0.05%, Fe 0.2%, Zn 0.04%, Al 98.31%; Mn and Cr were added based on the composition of Example 3 to refine the grains and further improve the corrosion resistance.

[0049] (2) Processing steps:

[0050] Solution treatment: Adjust the thickness of the board to 12mm, heat to 565℃ at 5℃ / min, and hold for 80 minutes;

[0051] Rapid quenching: A composite cooling method of surface water mist quenching and core water quenching is adopted, with a surface cooling rate of 130℃ / min and a core cooling rate of 170℃ / min;

[0052] Controlled storage: Place in an environment of 24℃ and 48% humidity for 36 hours;

[0053] Artificial aging: Heat to 160℃ at 3℃ / min and hold for 3 hours, then heat to 175℃ and hold for 4 hours, then cool to room temperature with the furnace.

[0054] Example 5:

[0055] (1) Alloy composition (mass percentage): Mg 1.1%, Si 0.7%, Cu 0.28%, Mn 0.18%, Cr 0.09%, Fe 0.32%, Zn 0.08%, Al 97.25%; Based on the composition framework of Example 4, the ratio of multiple elements was optimized to adapt to the ultra-long parking window;

[0056] (2) Processing steps:

[0057] Solution treatment: Adjust the thickness of the board to 20mm, heat to 575℃ at 5℃ / min, and hold for 120 minutes;

[0058] Rapid quenching: High-pressure water mist quenching is used for cooling, with a cooling rate of 140℃ / min;

[0059] Controlled storage: Place in an environment of 28℃ and 52% humidity for 72 hours;

[0060] Artificial aging: Heat to 180℃ at 3℃ / min and hold for 2 hours, then heat to 185℃ and hold for 3 hours, then cool to room temperature with the furnace.

[0061] Comparative Example 1:

[0062] (1) Alloy composition: completely consistent with Example 1, namely Mg 0.6%, Si 0.4%, Fe 0.2%, Zn 0.05%, Al 98.75%;

[0063] (2) Processing steps:

[0064] Solution treatment: Same as in Example 1, heat at 550°C for 60 minutes;

[0065] Rapid quenching: Same as in Example 1, water quenching cooling rate 150℃ / min;

[0066] Natural resting: After quenching, the product is placed at room temperature for 12 hours without temperature and humidity control, and subsequent processes are arranged according to the production rhythm.

[0067] Artificial aging: Same as in Example 1, heat preservation at 170℃ for 4 hours.

[0068] Comparative Example 2:

[0069] (1) Alloy composition: completely consistent with Example 2, namely Mg 0.9%, Si 0.6%, Fe 0.25%, Zn 0.06%, Al 98.19%;

[0070] (2) Processing steps:

[0071] Solution treatment: Same as in Example 2, heat treatment at 560°C for 70 minutes;

[0072] Rapid quenching: Same as in Example 2, water mist quenching cooling rate 120℃ / min;

[0073] Extended storage period: 96 hours at room temperature;

[0074] Artificial aging: Same as in Example 2, heat preservation at 175°C for 5 hours.

[0075] Comparative Example 3:

[0076] (1) Alloy composition: Mg 0.5%, Si 0.3%, Fe 0.2%, Zn 0.05%, Al 98.95%, without trace alloying elements such as Cu, Mn, and Cr;

[0077] (2) Processing steps:

[0078] Solution treatment: Hold at 540℃ for 50 minutes;

[0079] Rapid quenching: water quenching cooling rate 140℃ / min;

[0080] Natural placement: Placed at room temperature for 8 hours, without precise control;

[0081] Artificial aging: 170℃ for 6 hours.

[0082] Comparative Example 4:

[0083] (1) Alloy composition: completely consistent with Example 3, namely Mg 0.8%, Si 0.5%, Cu 0.2%, Fe 0.22%, Zn 0.05%, Al 98.23%;

[0084] (2) Processing steps:

[0085] Solution treatment: Same as in Example 3, heat treatment at 570°C for 90 minutes;

[0086] Rapid quenching: Same as in Example 3, water quenching cooling rate 160℃ / min;

[0087] Natural resting: After quenching, the temperature is left at room temperature for 24 hours without precise control;

[0088] Artificial aging: Same as in Example 3, heat preservation at 165℃ for 2 hours + heat preservation at 180℃ for 3 hours.

[0089] Performance testing and results analysis:

[0090] (1) Testing standards:

[0091] (1) Mechanical properties were tested according to GB / T228.1-2010 "Metallic materials, tensile testing - Part 1: Room temperature test method", yield strength, tensile strength and elongation were tested;

[0092] (2) The corrosion performance is evaluated according to GB / T7999-2015 "Aluminum and Aluminum Alloys Corrosion Test Methods Part 1 Intergranular Corrosion Test" and GB / T22639-2018 "Aluminum and Aluminum Alloys Exfoliation Corrosion Test Method".

[0093] The test results are shown in Table 1 below:

[0094] Group Yield strength (MPa) Tensile strength (MPa) Elongation (%) Intergranular corrosion level Peeling corrosion level Example 1 315 340 12.5 Level 1 Level 1 Example 2 330 365 11.8 Level 1 Level 1 Example 3 345 380 11.2 Level 1 Level 1 Example 4 350 385 12.0 Level 1 Level 1 Example 5 362 398 10.8 Level 1 Level 1 Comparative Example 1 280 310 10.5 Level 2 Level 2 Comparative Example 2 260 295 9.8 Level 2 Level 2 Comparative Example 3 275 305 10.2 Level 2 Level 2 Comparative Example 4 302 335 10.6 Level 2 Level 2

[0095] Test results show that the 6xxx aluminum alloys produced in each embodiment of the present invention are significantly superior to those in the comparative examples in terms of mechanical properties and corrosion resistance.

[0096] (1) In terms of mechanical properties, the yield strength of Examples 1 to 5 was consistently above 300 MPa, reaching a maximum of 362 MPa, and the tensile strength was simultaneously increased to 398 MPa. Compared with the yield strength of 280 MPa and the tensile strength of 310 MPa of the conventional T6 process in Comparative Example 1, the yield strength and tensile strength were increased by 29.3% and 28.4%, respectively. Even compared with Comparative Example 4, which used the same modified composition but did not control the storage time, the yield strength and tensile strength of Example 3 were 14.2% and 13.4% higher, respectively. At the same time, the elongation of all examples remained above 10%, with the elongation of Example 1 reaching 12.5%, achieving a good balance between high strength and high plasticity. In terms of corrosion resistance, the intergranular corrosion level and exfoliation corrosion level of each example reached level 1, while all comparative examples were level 2, indicating that the synergistic control system of composition, process, and storage time of the present invention not only optimized the mechanical properties but also simultaneously improved the corrosion resistance of the alloy.

[0097] (2) With the synergistic optimization of multiple trace elements in the alloy composition and the precise matching of process parameters and resting time, the mechanical properties show a steady upward trend, proving that the control system established by this invention has good scalability and adaptability. The test results of Comparative Example 2 show that after the resting time exceeds the upper limit of 72 hours specified by this invention, the yield strength and tensile strength drop to 260MPa and 295MPa respectively, which is significantly lower than that of Example 2, directly confirming the key role of the resting time window specified by this invention in avoiding the softening phenomenon during resting. In summary, the test results fully verify the effectiveness and superiority of the technical solution of this invention. The comprehensive performance improvement effect it brings is significant, and the process is simple and low-cost, possessing extremely strong industrial application value.

[0098] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A processing method for optimizing the mechanical properties of 6xxx aluminum alloy based on controlling the dwell time, characterized in that, Includes the following steps: (1) Prepare 6xxx aluminum alloy raw materials, wherein the mass percentage of the raw materials is: Mg 0.4%-1.2%, Si 0.2%-0.8%, Cu 0.05%-0.3%, Mn 0.05%-0.2%, Cr 0.01%-0.1%, Fe≤0.35%, Zn≤0.1%, and the remainder is Al and unavoidable trace impurities; (2) Solution treatment: Place the aluminum alloy workpiece in a heating furnace, heat it to 530℃-580℃, and hold it for 10 minutes to 8 hours; (3) Rapid quenching: After solution treatment, the workpiece is rapidly cooled at a rate of not less than 100℃ / min; (4) Controllable storage: Place the quenched workpiece in a room temperature environment of 15℃-30℃ for 4 hours-72 hours, and keep the ambient temperature and humidity stable during the storage period; (5) Artificial aging: Place the stored workpiece in an aging furnace, heat it to 160℃-185℃, keep it at that temperature for 1 hour-10 hours, and then cool it to room temperature with the furnace.

2. The processing method according to claim 1, characterized in that, The raw materials contain 0.6%-1.1% Mg and 0.4%-0.7% Si.

3. The processing method according to claim 1, characterized in that, The heating rate for solution treatment is 5℃ / min.

4. The processing method according to claim 1, characterized in that, The cooling methods for rapid quenching include water quenching, water mist quenching, or a combination of surface water mist quenching and core water quenching.

5. The processing method according to claim 1, characterized in that, The controlled humidity of the parking environment is 45%-55%.

6. The processing method according to claim 1, characterized in that, Artificial aging adopts a segmented heating and holding method: first, the temperature is raised to 160℃-165℃ and held for 2-3 hours, then the temperature is raised to 175℃-185℃ and held for 3-4 hours.

7. The processing method according to claim 1, characterized in that, The Cu content in the raw material is 0.15%-0.28%.

8. The processing method according to claim 1, characterized in that, The heat treatment time for solution treatment is adjusted according to the thickness of the workpiece. When the workpiece thickness is 10mm-20mm, the heat treatment time is 60 minutes-120 minutes.

9. The processing method according to claim 1, characterized in that, The cooling rate for rapid quenching is 120℃ / min-170℃ / min.

10. The processing method according to claim 1, characterized in that, The controllable parking time is 6 hours to 60 hours.