A method for processing a 7-series aluminum alloy

Abstract

The application discloses a processing method of a 7-series aluminum alloy, and overcomes the contradiction that high strength and high corrosion resistance of the existing 7-series aluminum alloy cannot be compatible, and solves the problems that material performance of the existing 7-series aluminum alloy is not fully utilized or a multi-stage aging process is complicated and has poor applicability. The application can well solve the above problems, the new method is simple to operate, the prepared 7-series aluminum alloy material has higher strength and better corrosion resistance, and meets the use requirement; in addition, combined with optimization of a chemical composition, addition of certain Zr and Sc elements, synergistic inhibition of recrystallization, the strength of the aluminum alloy is improved, combined with the Mn element, synergistic provision of the toughness of the aluminum alloy, the Sc forms Al3Sc nanoparticles, refines the structure and improves the corrosion resistance, combined with a subsequent processing process, further reduction of galvanic corrosion of grain boundary precipitates, and overall, the 7-series aluminum alloy with the strength, toughness and corrosion resistance meeting the requirement is obtained.

Description

Technical Field

[0001] This invention relates to the field of materials processing, and more specifically, to a processing method for 7-series aluminum alloys. Background Technology

[0002] 7-series aluminum alloys are a typical medium-strength alloy in the Al-Zn-Mg system. These alloys possess good plasticity and moderate strength after artificial aging. 7-series aluminum alloys are a good choice for aluminum alloy towers. However, since online quenching after extrusion of 7-series alloys generally cannot achieve the desired solution treatment effect, offline quenching is required to obtain higher strength and mechanical properties. Offline quenching, however, increases manufacturing costs. After solution quenching and aging processes, excellent working performance can be obtained. The heat treatment process of aluminum alloys directly affects the microstructure changes, recrystallization, and the degree of solid solution of strengthening elements, thus affecting the final mechanical properties of the alloy. With the urgent market demand for higher-performance 7-series aluminum alloys, the conventional heat treatment methods currently used can no longer meet current production requirements. Currently, comprehensive properties such as strength, fracture toughness, and corrosion resistance have become the main evaluation indicators for high-performance aluminum alloys. 7-series aluminum alloys have various aging treatment regimes. Peak aging can give aluminum alloys high strength, but poor corrosion resistance and fracture toughness. Over-aging (T74) can improve the corrosion resistance and fracture toughness of aluminum alloys, but at the cost of strength. Therefore, there is an urgent need for a processing method that can simultaneously improve the strength, fracture toughness and corrosion resistance of aluminum alloys, so that the strength, fracture toughness and corrosion resistance can all meet market demands.

[0003] Furthermore, current conventional aging processes for 7-series aluminum alloys are generally single-stage aging or two-stage aging (low temperature followed by high temperature). These processes typically sacrifice some strength to achieve over-aging and improve corrosion resistance. Regression aging or three-stage aging involves a brief high-temperature regression treatment, resulting in high equipment requirements, poor operational convenience, and a tendency for thicker materials to exhibit uneven performance. In the past decade or so, some non-isothermal aging processes and processes incorporating non-isothermal elements into regression aging have emerged. However, most of these processes use a constant heating rate, or while attempting to change the heating rate, the rate design is flawed, preventing the material's performance from being fully realized. All these processes also suffer from numerous operational steps, complex procedures, and high equipment requirements. Summary of the Invention

[0004] The purpose of this invention is to provide an aging heat treatment method for 7-series aluminum alloys, overcoming the contradiction between high strength, fracture toughness, and corrosion resistance in existing 7-series aluminum alloy aging methods. This method also addresses the problems of existing aging methods failing to fully utilize material properties or the cumbersome and unapplicable nature of multi-stage aging processes. This invention effectively solves the above problems. The proposed new method is simple to operate, and the prepared 7-series aluminum alloy material exhibits higher strength and better corrosion resistance, meeting application requirements. The specific technical solution is as follows:

[0005] A processing method for 7-series aluminum alloys includes the following steps:

[0006] 7-series aluminum alloy materials were prepared;

[0007] The 7-series aluminum alloy material to be processed is subjected to solution treatment or online quenching.

[0008] Then, the 7-series aluminum alloy material is pre-stretched by 0.5% to 3%;

[0009] The stretched 7-series aluminum alloy material is sawn to a set length and then left to stand naturally at room temperature for a duration of 0 < t0 ≤ 168 h.

[0010] The 7-series aluminum alloy material comprises the following components by mass percentage: Si: 0.2~0.5%, Fe: ≤0.2%, Cu: 1.2~2.3%, Mg: 1.3~2.6%, Mn: 0.1~0.3%, Zn: 4.1~6.7%, Ti: 0.05~0.08%, Zr: 0.01~0.03%, Sc: 0.03~0.05%, other individual elements ≤0.05%, total amount of other impurity elements ≤0.15%, and the balance being Al.

[0011] Furthermore, the preparation method of the 7-series aluminum alloy material also includes smelting, refining and impurity removal, continuous casting, and extrusion molding.

[0012] Furthermore, the melting temperature is 745–760℃. After all the aluminum alloy raw materials have melted, refining agents and covering agents are added, slag is removed, and the melt composition is tested online. After the composition is qualified, the melt is allowed to stand for 15–20 minutes to remove the gas and slag from the melt again. Then, it is continuously cast at a temperature of 700–720℃ to obtain an ingot, which is then extruded. The extrusion conditions are as follows: extrusion cylinder temperature is 400–450℃, extrusion die temperature is 450–470℃, ingot preheating temperature is 460–480℃, extrusion ratio is 10–30, and extrusion speed is 1.0–3.0 mm / min.

[0013] Further, the artificial aging treatment stage: The 7-series aluminum alloy material is then placed in an aging furnace and heated from the current starting temperature to 130-150°C at a first heating rate V1. It is then heated to 170-220°C at a second heating rate V2. It is then cooled to 130-150°C and the starting temperature at a second cooling rate V21 and a first cooling rate V11, respectively. Finally, it is heated to 130-170°C again at a third heating rate V3. Finally, the 7-series aluminum alloy material is removed from the aging furnace and cooled to room temperature, completing the treatment of the 7-series aluminum alloy material.

[0014] Furthermore, the stretching treatment is carried out at room temperature, with an elongation of 2%-3%.

[0015] Furthermore, the natural resting time at room temperature is: 0 < t0 ≤ 72h.

[0016] Furthermore, the first heating rate V1 is: 5℃≤V1≤20℃ / h; the first cooling rate V11 is: 5℃≤V11≤20℃ / h.

[0017] Furthermore, the first heating rate V1 is: 5℃≤V1≤10℃ / h; the first cooling rate V11 is: 5℃≤V11≤10℃ / h.

[0018] Furthermore, the second heating rate V2 is: 20℃≤V2≤40℃ / h; the second cooling rate V21 is: 20℃≤V21≤40℃ / h.

[0019] Furthermore, the third heating rate V3 is: 5℃≤V3≤40℃ / h.

[0020] 1. The purpose of this invention is to provide a processing method for 7-series aluminum alloy materials, which overcomes the contradiction that existing 7-series aluminum alloys cannot simultaneously achieve strength, toughness, and corrosion resistance, and the prepared 7-series aluminum alloy materials have better strength, toughness, and corrosion resistance, thus meeting the application requirements.

[0021] 2. This application optimizes the composition of 7-series aluminum alloys by adding certain Zr and Sc elements to synergistically inhibit recrystallization, which helps to improve the strength of the aluminum alloy. At the same time, combined with Mn elements, it synergistically provides the toughness of the aluminum alloy. Furthermore, Sc forms Al3Sc nanoparticles, which refine the microstructure and improve corrosion resistance. Combined with subsequent processing, it further reduces galvanic corrosion of grain boundary precipitates, resulting in a 7-series aluminum alloy that meets the requirements for strength, toughness, and corrosion resistance. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to its embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of the invention.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] This invention provides a processing method for 7-series aluminum alloys, comprising the following steps:

[0025] 7-series aluminum alloy materials were prepared;

[0026] The 7-series aluminum alloy material to be processed is subjected to solution treatment or online quenching.

[0027] After solution treatment or online quenching, the aluminum alloy material is left to stand naturally at room temperature for 0-168 hours. Then, in an aging furnace, the material is heated from room temperature or above a temperature T1 at a first heating rate V1 to a temperature T2 between 130-150°C. Next, it is heated further at a second heating rate V2 to a temperature T3 between 170-220°C. Then, it is cooled sequentially at a second cooling rate V21 and a first cooling rate V11 to T2 and T1 respectively. Finally, it is heated again at a third heating rate V3 to a temperature T4 between 130-170°C, and then removed from the furnace and cooled to room temperature. This continuous heating and cooling process, followed by continuous heating again, results in a material with corrosion resistance comparable to or better than that of T73 aging, while its strength is significantly higher than that of ordinary T6 aging treatment.

[0028] A processing method for 7-series aluminum alloy according to one embodiment of the present invention includes the following steps:

[0029] 7-series aluminum alloy materials were prepared;

[0030] The 7-series aluminum alloy material to be processed is subjected to solution treatment or online quenching.

[0031] Then, the 7-series aluminum alloy material is pre-stretched by 0.5% to 3%;

[0032] The stretched 7-series aluminum alloy material is sawn to a set length and then left to stand naturally at room temperature for a duration of 0 < t0 ≤ 168 h.

[0033] Artificial aging treatment stage: The 7-series aluminum alloy material is then placed in an aging furnace and heated from the current starting temperature to 130-150℃ at a first heating rate V1. It is then heated to 170-220℃ at a second heating rate V2. It is then cooled to 130-150℃ and the starting temperature at a second cooling rate V21 and a first cooling rate V11, respectively. Finally, it is heated to 130-170℃ again at a third heating rate V3. Finally, the 7-series aluminum alloy material is removed from the aging furnace and cooled to room temperature, completing the treatment of the 7-series aluminum alloy material.

[0034] In one embodiment, the 7-series aluminum alloy material comprises the following components by mass percentage: Si: 0.2~0.5%, Fe: ≤0.2%, Cu: 1.2~2.3%, Mg: 1.3~2.6%, Mn: 0.1~0.3%, Zn: 4.1~6.7%, Ti: 0.05~0.08%, Zr: 0.01~0.03%, Sc: 0.03~0.05%, other individual elements ≤0.05%, total amount of other impurity elements ≤0.15%, and the balance being Al.

[0035] In one embodiment, the preparation method of the 7-series aluminum alloy material further includes smelting, refining and impurity removal, continuous casting, and extrusion molding.

[0036] In one embodiment, the melting temperature is 745–760°C. After all the aluminum alloy raw materials have melted, refining agents and covering agents are added, slag is removed, and the melt composition is tested online. After the composition is qualified, the melt is allowed to stand for 15–20 minutes to remove gas and slag from the melt again. Then, it is continuously cast at a temperature of 700–720°C to obtain an ingot, which is then extruded. The extrusion conditions are as follows: extrusion cylinder temperature is 400–450°C, extrusion die temperature is 450–470°C, ingot preheating temperature is 460–480°C, extrusion ratio is 10–30, and extrusion speed is 1.0–3.0 mm / min.

[0037] In one embodiment, the stretching treatment is performed at room temperature with an elongation of 2%-3%.

[0038] In one embodiment, the natural resting time at room temperature is: 0 < t0 ≤ 72h.

[0039] In one embodiment, the first heating rate V1 is less than the second heating rate V2; the first cooling rate V11 is less than the second cooling rate V21.

[0040] In one embodiment, the first heating rate V1 is: 5℃≤V1≤20℃ / h; the first cooling rate V11 is: 5℃≤V11≤20℃ / h.

[0041] In one embodiment, the first heating rate V1 is: 5℃≤V1≤10℃ / h; the first cooling rate V11 is: 5℃≤V11≤10℃ / h.

[0042] In one embodiment, the second heating rate V2 is: 20℃≤V2≤40℃ / h; the second cooling rate V21 is: 20℃≤V21≤40℃ / h.

[0043] In one embodiment, the third heating rate V3 is: 5℃≤V3≤40℃ / h.

[0044] In one embodiment, the starting temperature at which the 7-series aluminum alloy is heated in the aging furnace at a first heating rate V1 is room temperature, or a temperature higher than room temperature but less than 100°C.

[0045] In one embodiment, the solution treatment or online quenching temperature is 450-550°C.

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0047] The implementation schemes of the present invention will now be described in detail with reference to specific embodiments.

[0048] Example 1:

[0049] A processing method for 7-series aluminum alloys includes the following steps:

[0050] The 7-series aluminum alloy material comprises the following components by mass percentage: Si: 0.3%, Fe: 0.05%, Cu: 2.1%, Mg: 1.8%, Mn: 0.3%, Zn: 4.1%, Ti: 0.05%, Zr: 0.03%, Sc: 0.03%, other individual elements ≤0.05%, total amount of other impurity elements ≤0.15%, and the balance being Al;

[0051] Based on the composition of 7-series aluminum alloy, the raw materials were melted at 750℃. After the aluminum alloy raw materials were completely melted, refining agents and covering agents were added. Slag was removed, and the melt composition was tested online. After the composition was qualified, the melt was allowed to stand for 20 minutes to remove gas and slag from the melt again. Subsequently, it was continuously cast at 720℃ to obtain ingots, which were then extruded. The extrusion conditions were as follows: extrusion barrel temperature 420℃, extrusion die temperature 470℃, ingot preheating temperature 460℃, extrusion ratio 30, and extrusion speed 2.0 mm / min.

[0052] The 7-series aluminum alloy material to be processed is subjected to solution treatment or online quenching at 450℃.

[0053] The 7-series aluminum alloy material is then stretched with an elongation of 1%.

[0054] The stretched 7-series aluminum alloy material is sawn to a set length and then left to stand naturally at room temperature for 168 hours.

[0055] Artificial aging treatment stage: The 7-series aluminum alloy material is then placed in an aging furnace and heated from the current starting temperature to 130°C at a first heating rate V1. It is then heated to 170°C at a second heating rate V2. It is then cooled to 130°C and the starting temperature at a second cooling rate V21 and a first cooling rate V11, respectively. Finally, it is heated to 130°C again at a third heating rate V3. Finally, the 7-series aluminum alloy material is removed from the aging furnace and cooled to room temperature, completing the treatment of the 7-series aluminum alloy material.

[0056] The starting temperature for heating the 7-series aluminum alloy in the aging furnace at a heating rate V1 is room temperature.

[0057] The first heating rate V1 is 5℃ / h; the first cooling rate V11 is 5℃ / h.

[0058] The second heating rate V2 is 20℃ / h; the second cooling rate V21 is 20℃ / h.

[0059] The third heating rate V3 is 5℃ / h.

[0060] Example 2:

[0061] A processing method for 7-series aluminum alloys includes the following steps:

[0062] The 7-series aluminum alloy material comprises the following components by mass percentage: Si: 0.3%, Fe: 0.05%, Cu: 1.2%, Mg: 1.8%, Mn: 0.2%, Zn: 4.2%, Ti: 0.06%, Zr: 0.02%, Sc: 0.03%, other individual elements ≤0.05%, total amount of other impurity elements ≤0.15%, and the balance being Al;

[0063] Based on the composition of 7-series aluminum alloy, the raw materials were melted at 750℃. After the aluminum alloy raw materials were completely melted, refining agents and covering agents were added. Slag was removed, and the melt composition was tested online. After the composition was qualified, the melt was allowed to stand for 20 minutes to remove gas and slag from the melt again. Subsequently, it was continuously cast at 720℃ to obtain ingots, which were then extruded. The extrusion conditions were as follows: extrusion barrel temperature 420℃, extrusion die temperature 470℃, ingot preheating temperature 460℃, extrusion ratio 30, and extrusion speed 2.0 mm / min.

[0064] The 7-series aluminum alloy material to be processed is subjected to solution treatment or online quenching at 550℃.

[0065] The 7-series aluminum alloy material is then stretched with an elongation of 3%.

[0066] The stretched 7-series aluminum alloy material is sawn to a set length and then left to stand naturally at room temperature for 168 hours.

[0067] Artificial aging treatment stage: The 7-series aluminum alloy material is then placed in an aging furnace and heated from the current starting temperature to 150°C at a first heating rate V1. It is then heated to 220°C at a second heating rate V2. It is then cooled to 150°C and the starting temperature at a second cooling rate V21 and a first cooling rate V11, respectively. Finally, it is heated to 170°C at a third heating rate V3. The 7-series aluminum alloy material is then removed from the aging furnace and cooled to room temperature, completing the treatment of the 7-series aluminum alloy material.

[0068] The starting temperature for heating the 7-series aluminum alloy in the aging furnace at a heating rate V1 is room temperature.

[0069] The first heating rate V1 is 20℃ / h; the first cooling rate V11 is 20℃ / h.

[0070] The second heating rate V2 is 40℃ / h; the second cooling rate V21 is 40℃ / h.

[0071] The third heating rate V3 is 40℃ / h.

[0072] Example 3:

[0073] A processing method for 7-series aluminum alloys includes the following steps:

[0074] The 7-series aluminum alloy material comprises the following components by mass percentage: Si: 0.4%, Fe: 0.06%, Cu: 2.3%, Mg: 2.0%, Mn: 0.3%, Zn: 4.5%, Ti: 0.06%, Zr: 0.03%, Sc: 0.04%, other individual elements ≤0.05%, total amount of other impurity elements ≤0.15%, and the balance being Al;

[0075] Based on the composition of 7-series aluminum alloy, the raw materials were melted at 760℃. After the aluminum alloy raw materials were completely melted, refining agents and covering agents were added. Slag was removed, and the melt composition was tested online. After the composition was qualified, the melt was allowed to stand for 20 minutes to remove gas and slag from the melt again. Subsequently, it was continuously cast at 720℃ to obtain ingots, which were then extruded. The extrusion conditions were as follows: extrusion barrel temperature 450℃, extrusion die temperature 470℃, ingot preheating temperature 450℃, extrusion ratio 30, and extrusion speed 2.0 mm / min.

[0076] The 7-series aluminum alloy material to be processed is subjected to solution treatment or online quenching at 500℃.

[0077] The 7-series aluminum alloy material is then stretched with an elongation of 2%.

[0078] The stretched 7-series aluminum alloy material is sawn to a set length and then left to stand naturally at room temperature for 100 hours.

[0079] Artificial aging treatment stage: The 7-series aluminum alloy material is then placed in an aging furnace and heated from the current starting temperature to 140°C at a first heating rate V1. It is then heated to 200°C at a second heating rate V2. It is then cooled to 140°C and the starting temperature at a second cooling rate V21 and a first cooling rate V11, respectively. Finally, it is heated to 140°C again at a third heating rate V3. Finally, the 7-series aluminum alloy material is removed from the aging furnace and cooled to room temperature, completing the treatment of the 7-series aluminum alloy material.

[0080] The starting temperature for heating the 7-series aluminum alloy in the aging furnace at a heating rate V1 is 90°C.

[0081] The first heating rate V1 is 10℃ / h; the first cooling rate V11 is 10℃ / h.

[0082] The second heating rate V2 is 30℃ / h; the second cooling rate V21 is 30℃ / h.

[0083] The third heating rate V3 is 30℃ / h.

[0084] Example 4:

[0085] A processing method for 7-series aluminum alloys includes the following steps:

[0086] The 7-series aluminum alloy material comprises the following components by mass percentage: Si: 0.5%, Fe: 0.05%, Cu: 2.3%, Mg: 2.2%, Mn: 0.3%, Zn: 4.2%, Ti: 0.06%, Zr: 0.03%, Sc: 0.05%, other individual elements ≤0.05%, total amount of other impurity elements ≤0.15%, and the balance being Al;

[0087] Based on the composition of 7-series aluminum alloy, the raw materials were melted at 760℃. After the aluminum alloy raw materials were completely melted, refining agents and covering agents were added. Slag was removed, and the melt composition was tested online. After the composition was qualified, the melt was allowed to stand for 20 minutes to remove gas and slag from the melt again. Then, it was continuously cast at 720℃ to obtain ingots, which were then extruded. The extrusion conditions were as follows: extrusion barrel temperature 450℃, extrusion die temperature 470℃, ingot preheating temperature 460℃, extrusion ratio 30, and extrusion speed 2.0 mm / min.

[0088] The 7-series aluminum alloy material to be processed is subjected to solution treatment or online quenching at 480℃.

[0089] The 7-series aluminum alloy material is then stretched with an elongation of 2%.

[0090] The stretched 7-series aluminum alloy material is sawn to a set length and then left to stand naturally at room temperature for 72 hours.

[0091] Artificial aging treatment stage: The 7-series aluminum alloy material is then placed in an aging furnace and heated from the current starting temperature to 135°C at a first heating rate V1. It is then heated to 180°C at a second heating rate V2. It is then cooled to 135°C and the starting temperature at a second cooling rate V21 and a first cooling rate V11, respectively. Finally, it is heated to 135°C again at a third heating rate V3. Finally, the 7-series aluminum alloy material is removed from the aging furnace and cooled to room temperature, completing the treatment of the 7-series aluminum alloy material.

[0092] The starting temperature for heating the 7-series aluminum alloy in the aging furnace at a heating rate V1 is 50°C.

[0093] The first heating rate V1 is 15℃ / h; the first cooling rate V11 is 15℃ / h.

[0094] The second heating rate V2 is 25℃ / h; the second cooling rate V21 is 25℃ / h.

[0095] The third heating rate V3 is 25℃ / h.

[0096] Comparative Example 1:

[0097] Compared with Example 1, the composition of the 7-series aluminum alloy in Comparative Example 1 did not include Mn, but was otherwise the same as in Example 1.

[0098] Comparative Example 2:

[0099] Compared with Example 1, the composition of the 7-series aluminum alloy in Comparative Example 2 did not include Zr, but was otherwise the same as in Example 1.

[0100] Comparative Example 3:

[0101] Compared with Example 1, the composition of the 7-series aluminum alloy in Comparative Example 3 did not include Sc element, but was otherwise the same as that in Example 1.

[0102] Comparative Example 4:

[0103] Compared with Example 1, the process conditions in Comparative Example 4 are as follows, while the others are the same as in Example 1;

[0104] The starting temperature for heating the 7-series aluminum alloy in the aging furnace at a heating rate V1 is room temperature.

[0105] The first heating rate V1 is 20℃ / h; the first cooling rate V11 is 20℃ / h.

[0106] The second heating rate V2 is 5℃ / h; the second cooling rate V21 is 5℃ / h.

[0107] The third heating rate V3 is 15℃ / h.

[0108] Comparative Example 5:

[0109] Compared with Example 1, the process conditions in Comparative Example 5 are as follows, while the others are the same as in Example 1;

[0110] The starting temperature for heating the 7-series aluminum alloy in the aging furnace at a heating rate V1 is room temperature.

[0111] The first heating rate V1 is 20℃ / h; the first cooling rate V11 is 5℃ / h.

[0112] The second heating rate V2 is 10℃ / h; the second cooling rate V21 is 10℃ / h.

[0113] The third heating rate V3 is 3℃ / h.

[0114] The relevant performance tests were performed on the samples of 7-series aluminum alloy materials in Examples 1-4 and the comparative samples of 7-series aluminum alloy materials in Comparative Examples 1-5. The results are shown in Table 1 below.

[0115] Table 1:

[0116]

[0117] This invention provides an aging heat treatment method suitable for 7-series aluminum alloys, comprising the following steps: The aluminum alloy material, after solution treatment or online quenching, is allowed to stand naturally at room temperature for 0-168 hours. Then, the material is heated in an aging furnace from a temperature T1 at or above room temperature to a temperature T2 between 130-150°C at a first heating rate V1. Next, it is heated further at a second heating rate V2 to a temperature T3 between 170-220°C. Then, it is cooled sequentially at a second cooling rate V21 and a first cooling rate V11 to T2 and T1 respectively. Finally, it is heated again at a third heating rate V3 to a temperature T4 between 130-170°C. Finally, the material is removed from the furnace and cooled to room temperature. The material obtained after this continuous heating and cooling process using the two heating / cooling rates described in this invention, followed by continuous heating again, exhibits corrosion resistance comparable to or better than that of T73 aging, while its strength is significantly higher than that of ordinary T6 aging treatment. Furthermore, data analysis from Comparative Examples 1 to 3 shows that by optimizing the chemical composition, this application also helps to improve the strength, toughness, and corrosion resistance of 7-series aluminum alloys, resulting in 7-series aluminum alloys with overall strength, toughness, and corrosion resistance meeting the requirements.

[0118] The purpose of this invention is to provide an aging heat treatment method for 7-series aluminum alloys, overcoming the contradiction between high strength and high corrosion resistance in existing 7-series aluminum alloy aging methods. This method also addresses the problems of existing aging methods failing to fully utilize material properties or the cumbersome and unsuitable nature of multi-stage aging processes. This invention effectively solves the above problems. The proposed new method is simple to operate, and the prepared 7-series aluminum alloys exhibit higher strength and better corrosion resistance, meeting application requirements.

[0119] With simple modifications, those skilled in the art can also apply this invention to the aging heat treatment of other aluminum alloys such as 6-series and 2-series.

[0120] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0121] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A processing method for 7-series aluminum alloys, characterized in that, Includes the following steps: 7-series aluminum alloy materials were prepared; The 7-series aluminum alloy material to be processed is subjected to solution treatment or online quenching. Then, the 7-series aluminum alloy material is pre-stretched by 0.5% to 3%; The stretched 7-series aluminum alloy material is sawn to a set length and then left to stand naturally at room temperature for a duration of 0 < t0 ≤ 168 h. The 7-series aluminum alloy material comprises the following components by mass percentage: Si: 0.2~0.5%, Fe: ≤0.2%, Cu: 1.2~2.3%, Mg: 1.3~2.6%, Mn: 0.1~0.3%, Zn: 4.1~6.7%, Ti: 0.05~0.08%, Zr: 0.01~0.03%, Sc: 0.03~0.05%, other individual elements ≤0.05%, total amount of other impurity elements ≤0.15%, and the balance being Al; The 7-series aluminum alloy material also includes an artificial aging treatment stage: the 7-series aluminum alloy material is then placed in an aging furnace and heated from the current starting temperature to 130~150℃ at a first heating rate V1, followed by heating at a second heating rate V2 to 170~220℃, then cooled sequentially at a second cooling rate V21 and a first cooling rate V11 to 130~150℃ and the starting temperature respectively, and finally heated again at a third heating rate V3 to 130~170℃. Finally, the 7-series aluminum alloy material is removed from the aging furnace and cooled to room temperature, completing the treatment of the 7-series aluminum alloy material. The first heating rate V1 is: 5℃≤V1≤20℃ / h; the first cooling rate V11 is: 5℃≤V11≤20℃ / h; the second heating rate V2 is: 20℃≤V2≤40℃ / h; the second cooling rate V21 is: 20℃≤V21≤40℃ / h; and the third heating rate V3 is: 5℃≤V3≤40℃ / h.

2. The processing method for 7-series aluminum alloys according to claim 1, characterized in that, The preparation method of the 7-series aluminum alloy material also includes smelting, refining and impurity removal, continuous casting and extrusion molding.

3. The processing method for 7-series aluminum alloys according to claim 2, characterized in that, The melting temperature is 745-760℃. After the aluminum alloy raw material is completely melted, refining agent and covering agent are added. Slag is removed, and the melt composition is tested online. After the composition is qualified, the melt is allowed to stand for 15-20 minutes to remove gas and slag from the melt again. Then, it is continuously cast at a temperature of 700-720℃ to obtain an ingot, which is then extruded. The extrusion conditions are as follows: extrusion cylinder temperature is 400-450℃, extrusion die temperature is 450-470℃, ingot preheating temperature is 460-480℃, extrusion ratio is 10-30, and extrusion speed is 1.0-3.0 mm / min.

4. The processing method for 7-series aluminum alloys according to claim 1, characterized in that, The stretching treatment is carried out at room temperature, with an elongation of 2%-3%.

5. The processing method for 7-series aluminum alloys according to claim 1, characterized in that, The natural resting time at room temperature is: 0 < t0 ≤ 72h.

6. The processing method for 7-series aluminum alloys according to claim 1, characterized in that, The first heating rate V1 is: 5℃≤V1≤10℃ / h; the first cooling rate V11 is: 5℃≤V11≤10℃ / h.

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