Heat treatment method for improving toughness of ZL205A alloy

Abstract

The invention relates to the technical field of heat treatment, and particularly discloses a heat treatment method for improving the obdurability of a ZL205A alloy, which comprises the following steps: step 1, pretreatment: heating the ZL205A alloy to 320-350 DEG C, preserving heat for 1.5-2.5 hours, and then slowly cooling to room temperature at a rate of 10 DEG C / min to reduce the residual stress in the alloy and improve the effect of subsequent heat treatment; step 2, solution treatment; step 3, intermediate annealing; step 4, primary aging treatment; step 5, secondary aging treatment; and 6, subzero treatment is conducted. By means of the innovative heat treatment technology, the performance of the ZL205A aluminum alloy is improved, the application range of the ZL205A aluminum alloy is expanded, high-quality and reliable material selection is provided for users, and technology progress and industry development are promoted.

Description

Technical Field

[0001] The invention relates to the technical field of heat treatment, in particular to a heat treatment method for improving the strength and toughness of a ZL205A alloy. Background Art

[0002] In the current field of engineering technology, aluminum alloys are widely used in aviation, aerospace, automobile and shipbuilding industries due to their light weight and high strength. ZL205A aluminum alloy, as a material with superior mechanical properties, shows its important value especially in the field of high-end manufacturing. However, traditional heat treatment methods still have limitations in improving the comprehensive performance of materials, especially in strengthening the alloy while maintaining or improving its toughness.

[0003] The traditional heat treatment process usually includes solution treatment, aging hardening and other steps, which are aimed at improving the strength and hardness of the material, but are not enough to fully optimize the material's microstructure to achieve the best mechanical properties. Especially when treating ZL205A aluminum alloy, due to the lack of effective means to refine the grain and control the internal stress, the performance of the material has not reached the ideal state.

[0004] In addition, cryogenic treatment, a technology that can significantly affect the microstructure and properties of materials, has not been fully utilized in the heat treatment process of ZL205A aluminum alloy. In existing technologies, cryogenic treatment is often regarded as an optional additional process and has not been effectively integrated with other heat treatment processes, which limits its potential in improving performance.

[0005] Therefore, there is a need to develop a new heat treatment technology that can integrate multiple steps such as solution treatment, intermediate annealing, aging treatment and cryogenic treatment to fully optimize the microstructure and mechanical properties of ZL205A aluminum alloy, especially in terms of improving the strength and toughness of the material, to meet the stringent requirements of high-performance materials in high-end manufacturing. Through this method, the application performance of the material can be greatly improved, promoting the further development of related industrial technologies. Summary of the invention

[0006] The object of the present invention is to provide a heat treatment method for improving the strength and toughness of ZL205A alloy, so as to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a heat treatment method for improving the strength and toughness of ZL205A alloy, comprising the following steps:

[0008] Step 1: Preprocessing:

[0009] Heat the ZL205A alloy to 320℃-350℃, keep it at this temperature for 1.5-2.5 hours, and then slowly cool it to room temperature at a rate of 10℃ / min to reduce the residual stress in the alloy and improve the effect of subsequent heat treatment;

[0010] Step 2: Solution treatment:

[0011] Heat the pretreated alloy to 520°C-540°C, keep it at that temperature for 2.5-3.5 hours, and then quickly cool it to room temperature by water cooling or liquid nitrogen cooling;

[0012] Step 3: Intermediate annealing:

[0013] Between the solution treatment and the primary aging treatment, an intermediate annealing is performed, where the alloy is heated to 440°C-460°C, kept at this temperature for 2-3 hours, and then slowly cooled to room temperature. The intermediate annealing can improve the microstructure of the alloy and increase its toughness.

[0014] Step 4: Primary aging treatment:

[0015] Heat the intermediate annealed alloy to 140°C-160°C and keep it warm for 4.5-5.5 hours;

[0016] Step 5: Secondary aging treatment:

[0017] Heat the alloy after primary aging treatment to 170°C-190°C and keep it at this temperature for 6.5-7.5 hours;

[0018] Step 6: Cryogenic treatment:

[0019] After the secondary aging treatment, the alloy is cryogenically treated; the alloy is placed in liquid nitrogen for 1.5-2.5 hours and then slowly heated to room temperature to further improve the strength and wear resistance of the alloy.

[0020] Preferably, in step 2, the specific steps of solution treatment are as follows:

[0021] Step 2.1, segmented rapid heating:

[0022] The pretreated alloy was heated to 400°C at a rate of 30°C / min, and then continued to be heated to 520°C-540°C at a rate of 50°C / min;

[0023] Step 2.2, gradient insulation:

[0024] Keep the temperature at 520℃-540℃ for 1 hour, then reduce the temperature to 500℃-520℃ and keep it for another 1-2 hours;

[0025] Step 2.3, variable speed rapid cooling:

[0026] Use water cooling or liquid nitrogen cooling, first quickly cool to 300°C at a rate of 80°C / min, and then continue to cool to room temperature at a rate of 100°C / min.

[0027] Preferably, in step 3, the specific steps of intermediate annealing are as follows:

[0028] Step 3.1, staged preheating:

[0029] The alloy is heated to 350°C-380°C in stages; first, heated to 300°C at a rate of 15°C / min and kept at this temperature for 0.25-0.5 hours; then, heated to 350°C-380°C at a rate of 10°C / min and kept at this temperature for 0.25-0.5 hours;

[0030] Step 3.2: Variable speed heating annealing:

[0031] In the heating annealing stage, the temperature is first raised to 400-420°C at a rate of 15°C / min and kept at that temperature for 0.5-1 hour; then, the temperature is further raised to 440-460°C at a rate of 20°C / min and kept at that temperature for 1.5-2 hours;

[0032] Step 3.3, gradient slow cooling:

[0033] In the slow cooling stage, a gradient cooling method is adopted; first, cooling to 350°C-380°C at a rate of 8°C / min, keeping warm for 0.5-1 hour; then, cooling to room temperature at a rate of 5°C / min.

[0034] Preferably, in step 4, the specific steps of the primary aging treatment are as follows:

[0035] Step 4.1: Rapid heating in stages:

[0036] The alloy after intermediate annealing is heated to 120°C-130°C at a rate of 20°C / min, and kept at this temperature for 0.5-1 hour; then the temperature is further heated to 140°C-160°C at a rate of 30°C / min;

[0037] Step 4.2, Gradient constant temperature aging:

[0038] Keep the temperature at 140-160°C for 2-3 hours, then reduce the temperature to 130-140°C and keep it for another 2-3 hours;

[0039] Step 4.3, variable speed and slow cooling:

[0040] Use water cooling or liquid nitrogen cooling, first quickly cool to 80℃-100℃ at a rate of 8℃ / min, and then continue to cool to room temperature at a rate of 10℃ / min.

[0041] Preferably, in step 5, the specific steps of the secondary aging treatment are as follows:

[0042] Step 5.1: Preheating in stages:

[0043] The alloy after primary aging treatment is first heated to 130-140°C at a rate of 15°C / min and kept at this temperature for 0.5-1 hour; then, it is further heated to 150-160°C at a rate of 10°C / min and kept at this temperature for 0.5-1 hour;

[0044] Step 5.2, Gradient heating aging:

[0045] In the heating aging stage, first heat to 160-170°C at a rate of 8°C / min and keep warm for 2-3 hours; then continue to heat to 170-190°C at a rate of 10°C / min and keep warm for 4.5-5.5 hours;

[0046] Step 5.3: Variable speed and slow cooling:

[0047] Use oil cooling or air cooling, first cool to 120℃-130℃ at a rate of 3℃ / min, and then continue to cool to room temperature at a rate of 5℃ / min.

[0048] Preferably, in step 6, the specific steps of cryogenic treatment are as follows:

[0049] Step 6.1, Gradual precooling:

[0050] Place the alloy after secondary aging treatment above liquid nitrogen, 5-10 cm from the surface of liquid nitrogen, and keep it for 5-10 minutes; then gradually move the alloy closer to the surface of liquid nitrogen, lowering it by 5 cm every 5 minutes until it is 10-20 cm from the surface of liquid nitrogen, and keep it for 15-30 minutes;

[0051] Step 6.2: Segmented cryogenic treatment:

[0052] The pre-cooled alloy is completely immersed in liquid nitrogen for 1-1.5 hours; then the alloy is taken out, placed at room temperature for 15-30 minutes, and then immersed in liquid nitrogen again for 0.5-1 hour;

[0053] Step 6.3: Gradient temperature recovery.

[0054] Preferably, the specific steps of the gradient temperature recovery in step 6.3 are: taking the cryogenically treated alloy out of liquid nitrogen and allowing it to naturally recover at room temperature for 15-30 minutes; then slowly heating it to 100-120°C at a rate of 3-5°C / min using a heating device, and keeping it warm for 30-60 minutes; finally, continuing to heat it to room temperature at a rate of 5-10°C / min.

[0055] The ZL205A aluminum alloy heat treatment method provided by the present invention brings a series of significant beneficial effects by comprehensively utilizing solid solution treatment, intermediate annealing, aging treatment and cryogenic treatment:

[0056] 1. Improvement of microstructure: The heat treatment process of the present invention includes a key step - cryogenic treatment, which can effectively refine the grains, thereby improving the microstructure of the alloy; the refined grains help to improve the yield strength and fatigue resistance of the material, so that the ZL205A aluminum alloy exhibits more superior performance under high load and complex stress conditions;

[0057] 2. Enhanced mechanical properties: Through optimized heat treatment process, especially combining cryogenic treatment with other traditional heat treatment processes, the present invention can significantly improve the comprehensive mechanical properties of the material; the results show that the strength and toughness of the aluminum alloy after the heat treatment process of the present invention are significantly improved, meeting more stringent engineering application requirements;

[0058] 3. Reduce internal stress: The slow rewarming process after cryogenic treatment helps to evenly distribute and release the stress inside the material; this effective management of stress greatly reduces the risk of deformation and fracture that may occur during the use of the material, and improves the stability and reliability of the material;

[0059] 4. Expanded application fields: The ZL205A aluminum alloy treated by the present invention has better performance indicators, so it can be expanded to more high-end application fields, such as aerospace, high-performance automobiles and military industries, which have extremely strict requirements on the performance of materials;

[0060] 5. Improve production efficiency and economy: The method of integrating multiple heat treatment steps not only improves the performance of the material, but also optimizes the production process and reduces processing time and cost. This method of improving efficiency and reducing costs helps to enhance the competitiveness of enterprises and also promotes the commercialization of related technologies.

[0061] In summary, the present invention not only improves the performance of ZL205A aluminum alloy through its innovative heat treatment technology, but also expands its application range, provides users with better quality and more reliable material options, and promotes technological progress and industrial development. DETAILED DESCRIPTION

[0062] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] Embodiment 1: A heat treatment method for improving the toughness of ZL205A alloy, comprising the following steps:

[0064] Step 1: Preprocessing:

[0065] The ZL205A alloy was heated to 320 °C, kept at this temperature for 2 h, and then slowly cooled to room temperature at a rate of 10 °C / min.

[0066] Step 2: Solution treatment:

[0067] Step 2.1: Rapid heating in stages:

[0068] The pretreated alloy was heated to 400°C at a rate of 30°C / min and then continued to be heated to 530°C at a rate of 50°C / min.

[0069] Step 2.2: Gradient insulation:

[0070] At a temperature of 530°C, keep it warm for 1 hour, then reduce the temperature to 510°C and keep it warm for another 1.5 hours.

[0071] Step 2.3: Variable speed rapid cooling:

[0072] Water cooling was used, firstly rapidly cooled to 300°C at a rate of 80°C / min, and then continued to cool to room temperature at a rate of 100°C / min.

[0073] Step 3: Intermediate annealing:

[0074] Step 3.1: Staged preheating:

[0075] The alloy was heated to 360°C in stages; first, heated to 300°C at a rate of 15°C / min and kept at that temperature for 0.3 hours; then, heated to 360°C at a rate of 10°C / min and kept at that temperature for 0.3 hours.

[0076] Step 3.2: Variable speed heating annealing:

[0077] In the heating annealing stage, the temperature is first raised to 410°C at a rate of 15°C / min and kept at that temperature for 0.5 hour; then, the temperature is further raised to 450°C at a rate of 20°C / min and kept at that temperature for 1.5 hours.

[0078] Step 3.3: Gradient slow cooling:

[0079] In the slow cooling stage, a gradient cooling method was adopted; first, the temperature was cooled to 360°C at a rate of 8°C / min and kept at that temperature for 0.5 hours; then, the temperature was continued to be cooled to room temperature at a rate of 5°C / min.

[0080] Step 4: Primary aging treatment:

[0081] Step 4.1: Rapid heating in stages:

[0082] The alloy after intermediate annealing was heated to 125°C at a rate of 20°C / min and kept at that temperature for 0.5 hours; then, the temperature was further heated to 150°C at a rate of 30°C / min.

[0083] Step 4.2: Gradient constant temperature aging:

[0084] At a temperature of 150°C, keep it warm for 2.5 hours, then reduce the temperature to 135°C and keep it warm for another 2.5 hours.

[0085] Step 4.3: Variable speed slow cooling:

[0086] Water cooling was used, firstly rapidly cooled to 90°C at a rate of 8°C / min, and then continued to cool to room temperature at a rate of 10°C / min.

[0087] Step 5: Secondary aging treatment:

[0088] Step 5.1: Segmented preheating:

[0089] The alloy after primary aging treatment was first heated to 135°C at a rate of 15°C / min and kept at that temperature for 0.5 hour; then, it was further heated to 155°C at a rate of 10°C / min and kept at that temperature for 0.5 hour.

[0090] Step 5.2: Gradient heating aging:

[0091] During the heating aging stage, the temperature was first raised to 165°C at a rate of 8°C / min and kept at that temperature for 2.5 hours; then the temperature was continued to be raised to 180°C at a rate of 10°C / min and kept at that temperature for 5 hours.

[0092] Step 5.3: Variable speed slow cooling:

[0093] The sample was cooled to 125°C at a rate of 3°C / min and then cooled to room temperature at a rate of 5°C / min.

[0094] Step 6: Cryogenic treatment:

[0095] Step 6.1: Gradual precooling:

[0096] The alloy after secondary aging treatment was placed above liquid nitrogen, 5 cm away from the liquid nitrogen surface, and kept for 5 minutes; then the alloy was gradually brought closer to the liquid nitrogen surface, lowered by 5 cm every 5 minutes, until it was 15 cm away from the liquid nitrogen surface, and kept for 20 minutes.

[0097] Step 6.2: Segmented cryogenic treatment:

[0098] The pre-cooled alloy was completely immersed in liquid nitrogen for 1.2 hours; then the alloy was taken out, placed at room temperature for 20 minutes, and then immersed in liquid nitrogen again for 0.8 hours.

[0099] Step 6.3: Gradient temperature recovery:

[0100] The cryogenically treated alloy was taken out of liquid nitrogen and allowed to naturally warm up at room temperature for 20 minutes; then the temperature was slowly raised to 110°C at a rate of 4°C / min using a heating device and kept at that temperature for 40 minutes; finally, the temperature was continued to be raised to room temperature at a rate of 8°C / min.

[0101] The following is Example 1: Specific experimental data description:

[0102] 1. Comparison of mechanical properties:

[0103] Tensile Strength:

[0104] Before treatment: 240MPa;

[0105] After treatment: 340MPa;

[0106] Yield Strength:

[0107] Before treatment: 140MPa;

[0108] After treatment: 230MPa;

[0109] Elongation:

[0110] Before treatment: 5%;

[0111] After treatment: 12%;

[0112] These data clearly show that after precisely controlled cooling, deep cold soaking and gradual temperature recovery, the overall mechanical properties of ZL205A alloy are significantly improved.

[0113] 2. Microstructure analysis:

[0114] Before treatment: Microstructural observation showed large and non-uniform grains, with obvious stress concentration at the grain boundaries;

[0115] After treatment: the grains are refined and highly evenly distributed. The stress concentration phenomenon is significantly alleviated and the grain boundaries are clearer;

[0116] 3. Corrosion resistance test:

[0117] Corrosion rate:

[0118] Before treatment: 0.13mm / year;

[0119] After treatment: 0.05mm / year;

[0120] The treated alloy also showed improvements in corrosion resistance and reduced corrosion rate, indicating that it is more suitable for long-term use in harsh environments.

[0121] 4. Hardness test:

[0122] Vickers hardness (HV):

[0123] Before treatment: 90HV;

[0124] After treatment: 140HV;

[0125] The significant increase in hardness means that the alloy's resistance to wear has been enhanced, which is critical in applications where higher wear resistance is required.

[0126] Embodiment 2, a heat treatment method for improving the toughness of ZL205A alloy, comprising the following steps:

[0127] Step 1: Preprocessing:

[0128] The ZL205A alloy was heated to 330 °C, kept at this temperature for 2.2 h, and then slowly cooled to room temperature at a rate of 10 °C / min.

[0129] Step 2: Solution treatment:

[0130] Step 2.1: Rapid heating in stages

[0131] The pretreated alloy was heated to 400°C at a rate of 30°C / min and then continued to be heated to 535°C at a rate of 50°C / min.

[0132] Step 2.2: Gradient insulation:

[0133] At a temperature of 535°C, keep it warm for 1.2 hours, then reduce the temperature to 515°C and keep it warm for another 1.8 hours.

[0134] Step 2.3: Variable speed rapid cooling:

[0135] Liquid nitrogen cooling was used, firstly rapidly cooled to 300°C at a rate of 80°C / min, and then continued to cool to room temperature at a rate of 100°C / min.

[0136] Step 3: Intermediate annealing:

[0137] Step 3.1: Staged preheating:

[0138] The alloy was heated to 370°C in stages; first, heated to 300°C at a rate of 15°C / min and kept at that temperature for 0.4 hours; then, heated to 370°C at a rate of 10°C / min and kept at that temperature for 0.4 hours.

[0139] Step 3.2: Variable speed heating annealing:

[0140] In the heating annealing stage, the temperature is first raised to 415°C at a rate of 15°C / min and kept at this temperature for 0.6 hours; then, the temperature is continued to be raised to 455°C at a rate of 20°C / min and kept at this temperature for 1.8 hours.

[0141] Step 3.3: Gradient slow cooling:

[0142] In the slow cooling stage, a gradient cooling method was adopted; first, the temperature was cooled to 370°C at a rate of 8°C / min and kept at that temperature for 0.6 hours; then, the temperature was continued to be cooled to room temperature at a rate of 5°C / min.

[0143] Step 4: Primary aging treatment:

[0144] Step 4.1: Rapid heating in stages:

[0145] The alloy after intermediate annealing was heated to 128°C at a rate of 20°C / min and kept at that temperature for 0.6 hours; then, the alloy was further heated to 155°C at a rate of 30°C / min.

[0146] Step 4.2: Gradient constant temperature aging:

[0147] At a temperature of 155°C, keep it warm for 2.8 hours, then reduce the temperature to 140°C and keep it warm for another 2.8 hours.

[0148] Step 4.3: Variable speed slow cooling:

[0149] Liquid nitrogen cooling was used, firstly rapidly cooled to 95°C at a rate of 8°C / min, and then continued to cool to room temperature at a rate of 10°C / min.

[0150] Step 5: Secondary aging treatment:

[0151] Step 5.1: Segmented preheating:

[0152] The alloy after primary aging treatment was first heated to 140°C at a rate of 15°C / min and kept at that temperature for 0.6 hours; then, it was further heated to 160°C at a rate of 10°C / min and kept at that temperature for 0.6 hours.

[0153] Step 5.2: Gradient heating aging:

[0154] During the heating aging stage, the temperature was first raised to 170°C at a rate of 8°C / min and kept at this temperature for 3 hours; then the temperature was continued to be raised to 185°C at a rate of 10°C / min and kept at this temperature for 5.2 hours.

[0155] Step 5.3: Variable speed slow cooling:

[0156] The sample was cooled to 130°C at a rate of 3°C / min and then cooled to room temperature at a rate of 5°C / min.

[0157] Step 6: Cryogenic treatment:

[0158] Step 6.1: Gradual precooling:

[0159] The alloy after secondary aging treatment was placed above liquid nitrogen, 8 cm from the surface of liquid nitrogen, and kept for 8 minutes; then the alloy was gradually brought closer to the surface of liquid nitrogen, lowered by 5 cm every 5 minutes, until it was 18 cm from the surface of liquid nitrogen, and kept for 25 minutes.

[0160] Step 6.2: Segmented cryogenic treatment:

[0161] The pre-cooled alloy was completely immersed in liquid nitrogen for 1.4 hours; then the alloy was taken out, placed at room temperature for 25 minutes, and then immersed in liquid nitrogen again for 0.6 hours.

[0162] Step 6.3: Gradient temperature recovery:

[0163] The cryogenically treated alloy was taken out of liquid nitrogen and allowed to naturally warm up at room temperature for 25 minutes; then the temperature was slowly raised to 115°C at a rate of 4.5°C / min using a heating device and kept at that temperature for 45 minutes; finally, the temperature was continued to be raised to room temperature at a rate of 9°C / min.

[0164] In order to further verify the beneficial effects of heat treatment of ZL205A alloy, a second round of experiments was conducted. This experiment was designed to confirm the repeatability and consistency of the previous experimental results. The following is a detailed description of the data from the second experiment:

[0165] 1. Comparison of mechanical properties:

[0166] Tensile Strength:

[0167] Before treatment: 235MPa (close to 240MPa in the initial experiment);

[0168] After treatment: 345MPa (close to 340MPa in the initial experiment);

[0169] Yield Strength:

[0170] Before treatment: 145MPa (close to 140MPa in the initial experiment);

[0171] After treatment: 225MPa (close to 230MPa in the initial experiment);

[0172] Elongation:

[0173] Before treatment: 6% (slightly higher than the initial experiment, which was 5%);

[0174] After treatment: 11% (close to 12% in the initial experiment);

[0175] These data further confirm that the mechanical properties of ZL205A alloy are significantly improved after a specific heat treatment process.

[0176] 2. Microstructure analysis:

[0177] Before treatment: Large and unevenly distributed grains were again observed, with stress concentration.

[0178] After treatment: the grains are refined, evenly distributed, and the grain boundaries are clearer, which is consistent with the results of the first experiment.

[0179] 3. Corrosion resistance test:

[0180] Corrosion rate:

[0181] Before treatment: 0.12 mm / year (very close to 0.13 mm / year in the initial experiment);

[0182] After treatment: 0.04 mm / year (slightly better than the 0.05 mm / year in the initial experiment);

[0183] The corrosion resistance test results of the second experiment further verified the improvement in corrosion resistance of the alloy after heat treatment.

[0184] 4. Hardness test:

[0185] Vickers hardness (HV):

[0186] Before treatment: 88 HV (close to 90 HV in the initial experiment);

[0187] After treatment: 138HV (close to 140HV in the initial experiment);

[0188] The consistency of the hardness test results reinforces previous findings that the wear resistance of ZL205A alloy can be significantly enhanced by heat treatment.

[0189] In summary, the high consistency between the two sets of experimental results effectively confirms that the specific heat treatment process can reliably improve the mechanical properties, corrosion resistance and hardness of ZL205A alloy, while further enhancing the overall performance of the material through microstructural optimization.

[0190] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A heat treatment method for improving the toughness of ZL205A alloy, characterized in that: The following steps are involved: Step 1: Preprocessing: Heat the ZL205A alloy to 320℃-350℃, keep it at this temperature for 1.5-2.5 hours, and then slowly cool it to room temperature at a rate of 10℃ / min to reduce the residual stress in the alloy and improve the effect of subsequent heat treatment; Step 2: Solution treatment: Heat the pretreated alloy to 520°C-540°C, keep it at that temperature for 2.5-3.5 hours, and then quickly cool it to room temperature by water cooling or liquid nitrogen cooling; Step 3: Intermediate annealing: Between the solution treatment and the primary aging treatment, an intermediate annealing is performed, where the alloy is heated to 440°C-460°C, kept at this temperature for 2-3 hours, and then slowly cooled to room temperature. The intermediate annealing can improve the microstructure of the alloy and increase its toughness. Step 4: Primary aging treatment: Heat the intermediate annealed alloy to 140°C-160°C and keep it warm for 4.5-5.5 hours; Step 5: Secondary aging treatment: Heat the alloy after primary aging treatment to 170°C-190°C and keep it at this temperature for 6.5-7.5 hours; Step 6: Cryogenic treatment: After the secondary aging treatment, the alloy is cryogenically treated; the alloy is placed in liquid nitrogen for 1.5-2.5 hours and then slowly heated to room temperature to further improve the strength and wear resistance of the alloy.

2. A heat treatment method for improving the toughness of ZL205A alloy according to claim 1, characterized in that: In step 2, the specific steps of solution treatment are as follows: Step 2.1, segmented rapid heating: The pretreated alloy was heated to 400°C at a rate of 30°C / min, and then continued to be heated to 520°C-540°C at a rate of 50°C / min; Step 2.2, gradient insulation: Keep the temperature at 520℃-540℃ for 1 hour, then reduce the temperature to 500℃-520℃ and keep it for another 1-2 hours; Step 2.3, variable speed rapid cooling: Use water cooling or liquid nitrogen cooling, first quickly cool to 300°C at a rate of 80°C / min, and then continue to cool to room temperature at a rate of 100°C / min.

3. A heat treatment method for improving the toughness of ZL205A alloy according to claim 2, characterized in that: In step 3, the specific steps of intermediate annealing are as follows: Step 3.1, staged preheating: The alloy is heated to 350°C-380°C in stages; first, heated to 300°C at a rate of 15°C / min and kept at this temperature for 0.25-0.5 hours; then, heated to 350°C-380°C at a rate of 10°C / min and kept at this temperature for 0.25-0.5 hours; Step 3.2: Variable speed heating annealing: In the heating annealing stage, the temperature is first raised to 400-420°C at a rate of 15°C / min and kept at that temperature for 0.5-1 hour; then, the temperature is further raised to 440-460°C at a rate of 20°C / min and kept at that temperature for 1.5-2 hours; Step 3.3, gradient slow cooling: In the slow cooling stage, a gradient cooling method is adopted; first, cooling to 350°C-380°C at a rate of 8°C / min, keeping warm for 0.5-1 hour; then, cooling to room temperature at a rate of 5°C / min.

4. A heat treatment method for improving the toughness of ZL205A alloy according to claim 3, characterized in that: In step 4, the specific steps of the primary aging treatment are as follows: Step 4.1: Rapid heating in stages: The alloy after intermediate annealing is heated to 120°C-130°C at a rate of 20°C / min, and kept at this temperature for 0.5-1 hour; then the alloy is heated to 140°C-160°C at a rate of 30°C / min; Step 4.2, Gradient constant temperature aging: Keep the temperature at 140-160°C for 2-3 hours, then reduce the temperature to 130-140°C and keep it for another 2-3 hours; Step 4.3, variable speed and slow cooling: Use water cooling or liquid nitrogen cooling, first quickly cool to 80℃-100℃ at a rate of 8℃ / min, and then continue to cool to room temperature at a rate of 10℃ / min.

5. A heat treatment method for improving the toughness of ZL205A alloy according to claim 4, characterized in that: In step 5, the specific steps of the secondary aging treatment are as follows: Step 5.1: Preheating in stages: The alloy after primary aging treatment is first heated to 130-140°C at a rate of 15°C / min and kept at this temperature for 0.5-1 hour; then, it is further heated to 150-160°C at a rate of 10°C / min and kept at this temperature for 0.5-1 hour; Step 5.2, Gradient heating aging: In the heating aging stage, first heat to 160-170°C at a rate of 8°C / min and keep warm for 2-3 hours; then continue to heat to 170-190°C at a rate of 10°C / min and keep warm for 4.5-5.5 hours; Step 5.3: Variable speed and slow cooling: Use oil cooling or air cooling, first cool to 120℃-130℃ at a rate of 3℃ / min, and then continue to cool to room temperature at a rate of 5℃ / min.

6. A heat treatment method for improving the toughness of ZL205A alloy according to claim 5, characterized in that: In step 6, the specific steps of deep cryogenic treatment are as follows: Step 6.1, Gradual precooling: Place the alloy after secondary aging treatment above liquid nitrogen, 5-10 cm from the surface of liquid nitrogen, and keep it for 5-10 minutes; then gradually move the alloy closer to the surface of liquid nitrogen, lowering it by 5 cm every 5 minutes until it is 10-20 cm from the surface of liquid nitrogen, and keep it for 15-30 minutes; Step 6.2: Segmented cryogenic treatment: The pre-cooled alloy is completely immersed in liquid nitrogen for 1-1.5 hours; then the alloy is taken out, placed at room temperature for 15-30 minutes, and then immersed in liquid nitrogen again for 0.5-1 hour; Step 6.3: Gradient temperature recovery.

7. A heat treatment method for improving the toughness of ZL205A alloy according to claim 6, characterized in that: The specific steps of the gradient temperature recovery in step 6.3 are as follows: take the cryogenically treated alloy out of liquid nitrogen and allow it to naturally recover at room temperature for 15-30 minutes; then slowly heat it to 100-120°C at a rate of 3-5°C / min using a heating device, and keep it warm for 30-60 minutes; finally, continue to heat it to room temperature at a rate of 5-10°C / min.