Aluminum alloy heat treatment method and aluminum alloy prepared therefrom

Abstract

The invention relates to an aluminum alloy heat treatment method and an aluminum alloy prepared therefrom, belonging to the technical field of aluminum alloy heat treatment, and the method comprises: the aluminum alloy comprises the following components by mass percentage: 1.8-2.2% magnesium; 0.8-1.2% copper; 0.4-0.6% silicon; 0.1-0.2% zirconium; 0.2-0.5% iron; 0.3-0.5% zinc; 0.05-0.07% chromium; 0.1-0.4% manganese; 1.6-2.0% titanium fiber; the remainder is aluminum and inevitable impurities; each component is weighed and mixed evenly, placed in a resistance furnace for smelting, and cast to obtain an aluminum alloy die casting; high-temperature heat treatment is performed, and quenching treatment is performed using a quenching liquid; the quenched aluminum alloy die casting is cooled to room temperature for cold deformation treatment; the cold-deformed aluminum alloy die casting is tempered; and the tempered aluminum alloy die casting is annealed. The aluminum alloy prepared by the invention has excellent tensile strength and fatigue resistance.

Description

Technical Field

[0001] The present invention relates to the field of aluminum alloy heat treatment and related technical fields, and in particular to an aluminum alloy heat treatment method and an aluminum alloy prepared therefrom. Background Art

[0002] The fatigue life of aluminum alloy is short, especially in low temperature environment, it is easy to produce fatigue failure, which greatly limits the scope of application.

[0003] Titanium fiber is an excellent reinforcing material with high mechanical strength and excellent fatigue resistance. However, titanium fiber is expensive and used in large quantities, generally exceeding 2.5%. In addition, the heat treatment process has a great influence on the reinforcing effect of titanium fiber. How to reduce the amount of titanium fiber in the process of preparing aluminum alloy while maintaining the excellent tensile and fatigue resistance of aluminum alloy is an urgent problem to be solved. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an aluminum alloy heat treatment method and an aluminum alloy prepared therefrom.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A method for heat treating an aluminum alloy comprises the following steps:

[0007] S1: The aluminum alloy comprises the following components by mass percentage: 1.8-2.2% magnesium; 0.8-1.2% copper; 0.4-0.6% silicon; 0.1-0.2% zirconium; 0.2-0.5% iron; 0.3-0.5% zinc; 0.05-0.07% chromium; 0.1-0.4% manganese; 1.6-2.0% titanium fiber; the remainder is aluminum and unavoidable impurities;

[0008] Reasonable selection and blending of alloy elements can optimize the performance of composite materials. The content of Mg element is further limited in the present invention. The addition of an appropriate amount of Mg element to the aluminum alloy is mainly for the purpose of solid solution strengthening, and the strength of the aluminum alloy matrix will increase with the increase of the amount of Mg element added, but the plasticity will decrease. If less than 1% manganese is added to the aluminum alloy matrix, it will supplement the strengthening effect, while reducing the tendency of hot cracking, improving corrosion resistance and welding performance, and significantly refining the recrystallized grains. Uniformly distributed titanium fibers can precipitate with the crystals of each element (mainly Mg-containing crystals) to form a bonding network, thereby improving the mechanical strength of the aluminum alloy. Therefore, the content of titanium fibers can further optimize the content of Mg element, that is:

[0009] Ti%+0.5(Mn%)≤Mg%≤Ti%+1.5(Mn%).

[0010] Weigh the various components of the aluminum alloy, mix them evenly, place them in a resistance furnace at 700-800°C for smelting, use existing mechanical stirring and / or ultrasonic treatment, and then cast them to obtain an aluminum alloy die casting with uniform titanium fiber distribution. The titanium fiber is not limited to titanium metal fiber, but can also be titanium alloy fiber.

[0011] S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 500-550°C for 4-6 hours, and then quenched with a quenching liquid for 1-3 hours, wherein the temperature of the quenching liquid is 50-70°C;

[0012] S3: Cooling the quenched aluminum alloy die casting to room temperature and performing cold deformation treatment, wherein the cold deformation amount of the cold-deformed aluminum alloy die casting is 3-7%;

[0013] S4: Temper the aluminum alloy die casting after cold deformation at 200~260℃ for 1~2h;

[0014] S5: Annealing the tempered aluminum alloy die casting at a temperature of 80-120°C for 10-14 hours.

[0015] Furthermore, the mass ratio of the titanium fiber to the aluminum is 46-59. Furthermore, the length of the titanium fiber is 50-150 μm, so as to ensure that the titanium fiber is evenly distributed and overlapped.

[0016] Furthermore, the aluminum alloy includes the following components, by mass percentage: 2.0% magnesium; 1.0% copper; 0.5% silicon; 0.15% zirconium; 0.35% iron; 0.4% zinc; 0.06% chromium; 0.25% manganese; 1.8% titanium fiber; the remainder is aluminum and unavoidable impurities.

[0017] Furthermore, the method for preparing the quenching liquid comprises the following steps:

[0018] A1: By weight, add 0.5-1 part of sodium acetate, 0.3-0.5 part of polyvinyl alcohol and 10-15 parts of water into a reaction kettle and mix evenly, heat to 80-90°C, stir for 0.5-1h to form a mixed solution 1;

[0019] A2: By weight, 20 parts of sodium polyacrylate, 3-4 parts of cellulose triacetate, 1.2-1.6 parts of polyethylene glycol and 20-30 parts of water are mixed, the temperature is raised to 55-65°C, and stirring is continued for 2-3 hours to form a mixed solution II;

[0020] A3: At room temperature, pour mixed solution 1 into mixed solution 2, stir for 20-40 minutes to obtain mixed solution 3, then add water and mixed solution 3 in a volume ratio of 5-6:1 to prepare a diluted solution, which is the quenching solution.

[0021] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0022] In order to reduce the cost, the present invention adds titanium fiber with a lower content.

[0023] The present invention adds titanium fibers with a relatively low content, so that the fibers are mainly overlapped at the sites, and when the elements in the alloy are crystallized and precipitated, a bonding network is formed between the overlapped sites of the fibers, so that the uniform distribution of the elements in the alloy is achieved, and then the quenching treatment is carried out by a specific quenching liquid, so as to reduce the thermal stress and tissue stress generated during the quenching of the metal; in addition, by coordinating with the cold deformation treatment process, a certain prestress is applied to the bonding network of the aluminum alloy fiber, so as to improve the reciprocating sliding ability of the fiber, reduce its fatigue damage under alternating stress, and greatly improve the fatigue resistance of the alloy.

[0024] 2. The present invention uses titanium fiber as a reinforcing material and combines a lower titanium fiber content with a specific heat treatment process to provide an aluminum alloy material that reduces manufacturing costs while having higher mechanical strength and excellent fatigue resistance. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. 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.

[0026] Example 1

[0027] The aluminum alloy includes the following components by mass percentage: 1.8% magnesium; 0.8% copper; 0.4% silicon; 0.1% zirconium; 0.2% iron; 0.3% zinc; 0.05% chromium; 0.4% manganese; 1.6% titanium fiber; the remainder is aluminum and unavoidable impurities. The mass ratio between titanium fiber and aluminum is 1:58.2. The length of titanium fiber is 50~150μm.

[0028] A method for heat treating an aluminum alloy comprises the following steps:

[0029] S1: Weigh each component of the aluminum alloy, mix them evenly, place them in a 700°C resistance furnace for smelting, and then cast them to obtain an aluminum alloy die casting;

[0030] S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 500°C for 4 hours, and then quenched with a quenching liquid for 1 hour, wherein the temperature of the quenching liquid is 50°C;

[0031] S3: cooling the quenched aluminum alloy die casting to room temperature and performing cold deformation treatment, wherein the cold deformation amount of the cold-deformed aluminum alloy die casting is 3%;

[0032] S4: Temper the aluminum alloy die casting after cold deformation at 200°C for 1h;

[0033] S5: performing annealing treatment on the tempered aluminum alloy die casting, the annealing temperature is 80° C., and the time is 10 h.

[0034] The method for preparing the quenching liquid comprises the following steps:

[0035] A1: By weight, 0.5 parts of sodium acetate, 0.3 parts of polyvinyl alcohol and 10 parts of water were added into a reaction kettle and mixed evenly, heated to 80°C, and stirred for 0.5h to form a mixed solution 1;

[0036] A2: By weight, 20 parts of sodium polyacrylate, 3 parts of cellulose triacetate, 1.2 parts of polyethylene glycol and 20 parts of water were mixed, the temperature was raised to 55°C, and stirring was continued for 2 hours to form a mixed solution II;

[0037] A3: At room temperature, pour mixed solution 1 into mixed solution 2, stir for 20 minutes to obtain mixed solution 3, then add water and mixed solution 3 in a volume ratio of 5:1 to prepare a diluent, which is the quenching solution.

[0038] Example 2

[0039] The aluminum alloy includes the following components by mass percentage: 2.0% magnesium; 1.0% copper; 0.5% silicon; 0.15% zirconium; 0.35% iron; 0.4% zinc; 0.06% chromium; 0.25% manganese; 1.8% titanium fiber; the remainder is aluminum and unavoidable impurities. The mass ratio of the titanium fiber to aluminum is 1:51.6. The length of the titanium fiber is 50-150 μm.

[0040] A method for heat treating an aluminum alloy comprises the following steps:

[0041] S1: Weigh various components of the aluminum alloy, mix them evenly, place them in a 750° C. resistance furnace for melting, and then cast them to obtain an aluminum alloy die-casting with uniform titanium fiber distribution.

[0042] S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 520°C for 5 hours, and then quenched with a quenching liquid for 2 hours, wherein the temperature of the quenching liquid is 60°C;

[0043] S3: cooling the quenched aluminum alloy die casting to room temperature and performing cold deformation treatment, wherein the cold deformation amount of the cold-deformed aluminum alloy die casting is 5%;

[0044] S4: Temper the aluminum alloy die casting after cold deformation at 230°C for 1.5h;

[0045] S5: performing annealing treatment on the tempered aluminum alloy die casting, the annealing temperature is 100° C., and the time is 12 h.

[0046] The method for preparing the quenching liquid comprises the following steps:

[0047] A1: By weight, 0.75 parts of sodium acetate, 0.4 parts of polyvinyl alcohol and 10 parts of water were added into a reaction kettle and mixed evenly, heated to 85°C, and stirred for 1 hour to form a mixed solution 1;

[0048] A2: By weight, 20 parts of sodium polyacrylate, 3.5 parts of cellulose triacetate, 1.4 parts of polyethylene glycol and 25 parts of water were mixed, the temperature was raised to 60°C, and stirring was continued for 3 hours to form a mixed solution II;

[0049] A3: At room temperature, pour mixed solution 1 into mixed solution 2 and stir for 30 minutes to obtain mixed solution 3. Then, water and mixed solution 3 are mixed in a volume ratio of 5.5:1 to prepare a diluent, which is the quenching solution.

[0050] Example 3

[0051] The aluminum alloy includes the following components by mass percentage: 2.2% magnesium; 1.2% copper; 0.6% silicon; 0.2% zirconium; 0.5% iron; 0.5% zinc; 0.07% chromium; 0.14% manganese; 2.0% titanium fiber; the remainder is aluminum and unavoidable impurities. The mass ratio of the titanium fiber to aluminum is 1:46.1. The length of the titanium fiber is 50-150 μm.

[0052] A method for heat treating an aluminum alloy comprises the following steps:

[0053] S1: Weigh various components of the aluminum alloy, mix them evenly, place them in an 800° C. resistance furnace for smelting, and then cast them to obtain aluminum alloy die castings.

[0054] S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 550°C for 6 hours, and then quenched with a quenching liquid for 3 hours, wherein the temperature of the quenching liquid is 70°C;

[0055] S3: cooling the quenched aluminum alloy die casting to room temperature and performing cold deformation treatment, wherein the cold deformation amount of the cold-deformed aluminum alloy die casting is 7%;

[0056] S4: Temper the aluminum alloy die casting after cold deformation at 260°C for 2h;

[0057] S5: performing annealing treatment on the tempered aluminum alloy die casting, the annealing temperature is 120° C., and the time is 14 h.

[0058] The method for preparing the quenching liquid comprises the following steps:

[0059] A1: By weight, 1 part of sodium acetate, 0.5 part of polyvinyl alcohol and 15 parts of water were added into a reaction kettle and mixed evenly, heated to 90°C, and stirred for 1 hour to form a mixed solution 1;

[0060] A2: By weight, 20 parts of sodium polyacrylate, 4 parts of cellulose triacetate, 1.6 parts of polyethylene glycol and 30 parts of water were mixed, the temperature was raised to 65°C, and stirring was continued for 3 hours to form a mixed solution II;

[0061] A3: At room temperature, pour mixed solution 1 into mixed solution 2, stir for 40 minutes to obtain mixed solution 3, and then use water and mixed solution 3 in a volume ratio of 6:1 to prepare a diluted solution, which is the quenching solution.

[0062] Example 4

[0063] The aluminum alloy includes the following components by mass percentage: 1.9% magnesium; 0.9% copper; 0.45% silicon; 0.15% zirconium; 0.25% iron; 0.35% zinc; 0.05% chromium; 0.35% manganese; 1.7% titanium fiber; the remainder is aluminum and unavoidable impurities. The mass ratio of the titanium fiber to aluminum is 1:55.1. The length of the titanium fiber is 50-150 μm.

[0064] A method for heat treating an aluminum alloy comprises the following steps:

[0065] S1: Weigh various components of the aluminum alloy, mix them evenly, place them in a 730° C. resistance furnace for melting, and then cast them to obtain aluminum alloy die castings.

[0066] S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 510°C for 4.6 hours, and then quenched with a quenching liquid for 1.5 hours, wherein the temperature of the quenching liquid is 55°C;

[0067] S3: cooling the quenched aluminum alloy die casting to room temperature and performing cold deformation treatment, wherein the cold deformation amount of the cold-deformed aluminum alloy die casting is 4%;

[0068] S4: Temper the aluminum alloy die casting after cold deformation at 210℃ for 1.4h;

[0069] S5: performing annealing treatment on the tempered aluminum alloy die casting, the annealing temperature is 90° C., and the time is 11 h.

[0070] The method for preparing the quenching liquid comprises the following steps:

[0071] A1: By weight, 0.6 parts of sodium acetate, 0.35 parts of polyvinyl alcohol and 11 parts of water were added into a reaction kettle and mixed evenly, heated to 84°C, and stirred for 0.7h to form a mixed solution 1;

[0072] A2: By weight, 20 parts of sodium polyacrylate, 3.4 parts of cellulose triacetate, 1.3 parts of polyethylene glycol and 23 parts of water were mixed, the temperature was raised to 58°C, and stirring was continued for 2.3 hours to form a mixed solution II;

[0073] A3: At room temperature, pour mixed solution 1 into mixed solution 2, stir for 25 minutes to obtain mixed solution 3, and then use water and mixed solution 3 in a volume ratio of 5.3:1 to prepare a diluted solution, which is the quenching solution.

[0074] Example 5

[0075] The aluminum alloy includes the following components by mass percentage: 2.1% magnesium; 1.1% copper; 0.55% silicon; 0.18% zirconium; 0.4% iron; 0.45% zinc; 0.065% chromium; 0.2% manganese; 1.9% titanium fiber; the remainder is aluminum and unavoidable impurities. The mass ratio of the titanium fiber to aluminum is 1:48.3. The length of the titanium fiber is 50-150 μm.

[0076] A method for heat treating an aluminum alloy comprises the following steps:

[0077] S1: Weigh various components of the aluminum alloy, mix them evenly, place them in a 780° C. resistance furnace for melting, and then cast them to obtain aluminum alloy die castings.

[0078] S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 540°C for 5.5 hours, and then quenched with a quenching liquid for 2.6 hours, wherein the temperature of the quenching liquid is 65°C;

[0079] S3: cooling the quenched aluminum alloy die casting to room temperature and performing cold deformation treatment, wherein the cold deformation amount of the cold-deformed aluminum alloy die casting is 6%;

[0080] S4: Temper the aluminum alloy die casting after cold deformation at 250°C for 1.8h;

[0081] S5: performing annealing treatment on the tempered aluminum alloy die casting, the annealing temperature is 110° C., and the time is 13 h.

[0082] The method for preparing the quenching liquid comprises the following steps:

[0083] A1: By weight, 0.9 parts of sodium acetate, 0.45 parts of polyvinyl alcohol and 14 parts of water were added into a reaction kettle and mixed evenly, heated to 88°C, and stirred for 0.8h to form a mixed solution 1;

[0084] A2: By weight, 20 parts of sodium polyacrylate, 3.8 parts of cellulose triacetate, 1.5 parts of polyethylene glycol and 28 parts of water were mixed, the temperature was raised to 64°C, and stirring was continued for 2.7 hours to form a mixed solution II;

[0085] A3: At room temperature, pour mixed solution 1 into mixed solution 2 and stir for 35 minutes to obtain mixed solution 3. Then, water and mixed solution 3 are mixed in a volume ratio of 5.7:1 to prepare a diluent, which is the quenching solution.

[0086] Comparative Example 1

[0087] The only difference from Example 2 is that during the heat treatment process, the quenching liquid in step S2 is replaced by water.

[0088] The aluminum alloy includes the following components by mass percentage: 2.0% magnesium; 1.0% copper; 0.5% silicon; 0.15% zirconium; 0.35% iron; 0.4% zinc; 0.06% chromium; 0.25% manganese; 1.8% titanium fiber; the remainder is aluminum and unavoidable impurities. The mass ratio between titanium fiber and aluminum is 1:51.6. The length of titanium fiber is 50~150μm.

[0089] A method for heat treating an aluminum alloy comprises the following steps:

[0090] S1: Weigh various components of the aluminum alloy, mix them evenly, place them in a 750° C. resistance furnace for smelting, and then cast them to obtain aluminum alloy die castings.

[0091] S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 520°C for 5 hours, and then quenched in water for 2 hours, wherein the water temperature is 60°C;

[0092] S3: cooling the quenched aluminum alloy die casting to room temperature and performing cold deformation treatment, wherein the cold deformation amount of the cold-deformed aluminum alloy die casting is 5%;

[0093] S4: Temper the aluminum alloy die casting after cold deformation at 230°C for 1.5h;

[0094] S5: performing annealing treatment on the tempered aluminum alloy die casting, the annealing temperature is 100° C., and the time is 12 h.

[0095] Comparative Example 2

[0096] The only difference from Example 2 is that during the heat treatment process, the cold deformation treatment in step S3 is not performed.

[0097] The aluminum alloy includes the following components by mass percentage: 2.0% magnesium; 1.0% copper; 0.5% silicon; 0.15% zirconium; 0.35% iron; 0.4% zinc; 0.06% chromium; 0.25% manganese; 1.8% titanium fiber; the remainder is aluminum and unavoidable impurities. The mass ratio between titanium fiber and aluminum is 1:51.6. The length of titanium fiber is 50~150μm.

[0098] A method for heat treating an aluminum alloy comprises the following steps:

[0099] S1: Weigh various components of the aluminum alloy, mix them evenly, place them in a 750° C. resistance furnace for smelting, and then cast them to obtain aluminum alloy die castings.

[0100] S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 520°C for 5 hours, and then quenched with a quenching liquid for 2 hours, wherein the temperature of the quenching liquid is 60°C;

[0101] S3: Temper the quenched aluminum alloy die casting at 230°C for 1.5h;

[0102] S4: performing annealing treatment on the tempered aluminum alloy die casting, the annealing temperature is 100° C., and the time is 12 h.

[0103] The method for preparing the quenching liquid comprises the following steps:

[0104] A1: By weight, 0.75 parts of sodium acetate, 0.4 parts of polyvinyl alcohol and 10 parts of water were added into a reaction kettle and mixed evenly, heated to 85°C, and stirred for 1 hour to form a mixed solution 1;

[0105] A2: By weight, 20 parts of sodium polyacrylate, 3.5 parts of cellulose triacetate, 1.4 parts of polyethylene glycol and 25 parts of water were mixed, the temperature was raised to 60°C, and stirring was continued for 3 hours to form a mixed solution II;

[0106] A3: At room temperature, pour mixed solution 1 into mixed solution 2 and stir for 30 minutes to obtain mixed solution 3. Then, water and mixed solution 3 are mixed in a volume ratio of 5.5:1 to prepare a diluent, which is the quenching solution.

[0107] Comparative Example 3

[0108] The only difference from Example 2 is that during the heat treatment process, the quenching liquid in step S2 is replaced by water, and the cold deformation treatment in step S2 is not performed.

[0109] The aluminum alloy includes the following components by mass percentage: 2.0% magnesium; 1.0% copper; 0.5% silicon; 0.15% zirconium; 0.35% iron; 0.4% zinc; 0.06% chromium; 0.25% manganese; 1.8% titanium fiber; the remainder is aluminum and unavoidable impurities. The mass ratio between titanium fiber and aluminum is 1:51.6. The length of titanium fiber is 50~150μm.

[0110] A method for heat treating an aluminum alloy comprises the following steps:

[0111] S1: Weigh various components of the aluminum alloy, mix them evenly, place them in a 750° C. resistance furnace for smelting, and then cast them to obtain aluminum alloy die castings.

[0112] S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 520°C for 5 hours, and then quenched in water for 2 hours, wherein the water temperature is 60°C;

[0113] S3: Temper the quenched aluminum alloy die casting at 230°C for 1.5h;

[0114] S4: performing annealing treatment on the tempered aluminum alloy die casting, the annealing temperature is 100° C., and the time is 12 h.

[0115] Comparative Example 4

[0116] Different from Example 2, no titanium fiber is added to the aluminum alloy composition.

[0117] The aluminum alloy includes the following components by mass percentage: 2.0% magnesium; 1.0% copper; 0.5% silicon; 0.15% zirconium; 0.35% iron; 0.4% zinc; 0.06% chromium; 0.25% manganese; the remainder is aluminum and unavoidable impurities.

[0118] A method for heat treating an aluminum alloy comprises the following steps:

[0119] S1: Weigh various components of the aluminum alloy, mix them evenly, place them in a 750° C. resistance furnace for smelting, and then cast them to obtain aluminum alloy die castings.

[0120] S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 520°C for 5 hours, and then quenched with a quenching liquid for 2 hours, wherein the temperature of the quenching liquid is 60°C;

[0121] S3: cooling the quenched aluminum alloy die casting to room temperature and performing cold deformation treatment, wherein the cold deformation amount of the cold-deformed aluminum alloy die casting is 5%;

[0122] S4: Temper the aluminum alloy die casting after cold deformation at 230°C for 1.5h;

[0123] S5: performing annealing treatment on the tempered aluminum alloy die casting, the annealing temperature is 100° C., and the time is 12 h.

[0124] Comparative Example 5

[0125] Different from Example 2, the content of titanium fiber in the aluminum alloy component is 2.6%.

[0126] The aluminum alloy includes the following components by mass percentage: 2.0% magnesium; 1.0% copper; 0.5% silicon; 0.15% zirconium; 0.35% iron; 0.4% zinc; 0.06% chromium; 0.25% manganese; 2.6% titanium fiber; the remainder is aluminum and unavoidable impurities. The mass ratio of the titanium fiber to aluminum is 1:35.7. The length of the titanium fiber is 50-150 μm.

[0127] A method for heat treating an aluminum alloy comprises the following steps:

[0128] S1: Weigh various components of the aluminum alloy, mix them evenly, place them in a 750° C. resistance furnace for smelting, and then cast them to obtain aluminum alloy die castings.

[0129] S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 520°C for 5 hours, and then quenched with a quenching liquid for 2 hours, wherein the temperature of the quenching liquid is 60°C;

[0130] S3: cooling the quenched aluminum alloy die casting to room temperature and performing cold deformation treatment, wherein the cold deformation amount of the cold-deformed aluminum alloy die casting is 5%;

[0131] S4: Temper the aluminum alloy die casting after cold deformation at 230°C for 1.5h;

[0132] S5: performing annealing treatment on the tempered aluminum alloy die casting, the annealing temperature is 100° C., and the time is 12 h.

[0133] The aluminum alloys of each embodiment and comparative example were processed into corresponding standard specimens, wherein the tensile strength was tested according to the standard GB / T16865-2023, and the fatigue resistance was tested according to the standard GB / T 3075-2020. The specimens were vibrated 300,000 times at 150 MPa, and the vibration frequency was 120 Hz. The elastic modulus of the specimens was tested before and after the fatigue test, and the fatigue resistance was expressed by the elastic modulus loss rate, wherein the elastic modulus loss rate = (elastic modulus before fatigue test - elastic modulus after fatigue test) / elastic modulus before fatigue test * 100%. The higher the elastic modulus loss rate, the worse the fatigue resistance of the aluminum alloy. The results are shown in Table 1.

[0134] Table 1

[0135] Tensile strength / MPa Elastic modulus loss rate (%) Example 1 628.3 2.6 Example 2 637.4 2.4 Example 3 634.8 2.5 Example 4 630.9 2.6 Example 5 632.6 2.7 Comparative Example 1 605.1 3.9 Comparative Example 2 618.9 5.1 Comparative Example 3 596.0 5.8 Comparative Example 4 601.4 3.7 Comparative Example 5 622.5 3.3

[0136] The tensile strength and elastic modulus loss rate of the aluminum alloy die-castings prepared by heat treatment in Example 1 to Example 5 in Table 1 indicate that when the amount of titanium fiber added is small, the aluminum alloy die-castings heat-treated by the technical scheme of the present invention have excellent tensile strength and fatigue resistance, which can meet the production needs and reduce production costs.

[0137] The only difference between Comparative Example 1 and Example 2 is that, during the heat treatment process, the quenching liquid in step S2 is replaced by water. The tensile strength of the aluminum alloy die-casting prepared by heat treatment in Comparative Example 1 is lower than the tensile strength of the aluminum alloy die-casting prepared by heat treatment in Example 2. The elastic modulus loss rate of the aluminum alloy die-casting prepared by heat treatment in Comparative Example 1 is higher than the elastic modulus loss rate of the aluminum alloy die-casting prepared by heat treatment in Example 2. It shows that under the premise of low addition of titanium fiber, the quenching liquid prepared by the present invention can reduce the thermal stress and structural stress generated during metal quenching during the heat treatment process, thereby helping to improve the tensile strength and fatigue resistance of the aluminum alloy die-casting.

[0138] The only difference between Comparative Example 2 and Example 2 is that the cold deformation treatment of step S3 is not performed during the heat treatment process. The tensile strength of the aluminum alloy die-casting prepared by heat treatment in Comparative Example 2 is lower than the tensile strength of the aluminum alloy die-casting prepared by heat treatment in Example 2. The elastic modulus loss rate of the aluminum alloy die-casting prepared by heat treatment in Comparative Example 2 is higher than the elastic modulus loss rate of the aluminum alloy die-casting prepared by heat treatment in Example 2. It shows that under the premise of low addition of titanium fiber, the cold deformation process of the present invention can apply a certain prestress to the tie network of aluminum alloy fibers, thereby helping to improve the tensile strength and fatigue resistance of aluminum alloy die-castings.

[0139] The only difference between Comparative Example 3 and Example 2 is that during the heat treatment process, the quenching liquid in step S2 is replaced by water, and the cold deformation treatment of step S2 is not performed. The tensile strength of the aluminum alloy die-casting prepared by heat treatment in Comparative Example 3 is lower than the tensile strength of the aluminum alloy die-casting prepared by heat treatment in Example 2. The elastic modulus loss rate of the aluminum alloy die-casting prepared by heat treatment in Comparative Example 3 is higher than the elastic modulus loss rate of the aluminum alloy die-casting prepared by heat treatment in Example 2. It shows that under the premise of low addition of titanium fiber, cold deformation treatment of aluminum alloy die-castings during heat treatment can improve the tensile strength and fatigue resistance of aluminum alloy die-castings.

[0140] Comparative Example 4 is different from Example 2 in that titanium fiber is not added to the aluminum alloy composition. The tensile strength of the aluminum alloy die casting prepared by heat treatment in Comparative Example 4 is lower than the tensile strength of the aluminum alloy die casting prepared by heat treatment in Example 2. Combining Example 2 and Comparative Example 4, it can be seen that titanium fiber can improve the tensile strength and fatigue resistance of the aluminum alloy die casting.

[0141] Comparative Example 5 is different from Example 2 in that the content of titanium fiber in the aluminum alloy composition is 2.6%. The tensile strength of the aluminum alloy die-casting prepared by heat treatment in Comparative Example 5 is lower than the tensile strength of the aluminum alloy die-casting prepared by heat treatment in Example 2. The elastic modulus loss rate of the aluminum alloy die-casting prepared by heat treatment in Comparative Example 5 is higher than the elastic modulus loss rate of the aluminum alloy die-casting prepared by heat treatment in Example 2.

[0142] In summary, under the premise of low addition of titanium fiber, combined with the final tensile strength and fatigue resistance of the aluminum alloy die-castings after heat treatment of the aluminum alloy die-castings in Comparative Examples 1 to 5, it can be seen that by limiting the addition amount of titanium fiber in the aluminum alloy and using the quenching liquid prepared by the present invention to quench before cold deformation during the heat treatment process, the two work together to improve the tensile strength and fatigue resistance of the aluminum alloy die-castings after heat treatment.

[0143] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for heat treatment of aluminum alloy, characterized in that: The following steps are involved: S1: The aluminum alloy comprises the following components by mass percentage: 1.8-2.2% magnesium; 0.8~1.2% copper; 0.4~0.6% silicon; 0.1~0.2% zirconium; 0.2~0.5% iron; 0.3~0.5% zinc; 0.05~0.07% chromium; 0.1~0.4% manganese; 1.6~2.0% titanium fiber; the balance is aluminum and unavoidable impurities; Weigh each component of the aluminum alloy, mix them evenly, place them in a resistance furnace at 700-800°C for smelting, and then cast them to obtain aluminum alloy die castings; S2: The aluminum alloy die casting is subjected to high temperature heat treatment at 500-550°C for 4-6 hours, and then quenched with a quenching liquid for 1-3 hours, wherein the temperature of the quenching liquid is 50-70°C; The method for preparing the quenching liquid comprises the following steps: A1: By weight, add 0.5-1 part of sodium acetate, 0.3-0.5 part of polyvinyl alcohol and 10-15 parts of water into a reaction kettle and mix evenly, heat to 80-90°C, stir for 0.5-1h to form a mixed solution 1; A2: By weight, 20 parts of sodium polyacrylate, 3-4 parts of cellulose triacetate, 1.2-1.6 parts of polyethylene glycol and 20-30 parts of water are mixed, the temperature is raised to 55-65°C, and stirring is continued for 2-3 hours to form a mixed solution II; A3: At room temperature, pour mixed solution 1 into mixed solution 2, stir for 20-40 minutes to obtain mixed solution 3, then add water and mixed solution 3 in a volume ratio of 5-6:1 to prepare a dilution solution, which is the quenching solution; S3: Cooling the quenched aluminum alloy die casting to room temperature and performing cold deformation treatment, wherein the cold deformation amount of the cold-deformed aluminum alloy die casting is 3-7%; S4: Temper the aluminum alloy die casting after cold deformation at 200~260℃ for 1~2h; S5: Annealing the tempered aluminum alloy die casting at a temperature of 80-120°C for 10-14 hours.

2. The aluminum alloy heat treatment method according to claim 1, characterized in that: The aluminum alloy comprises the following components, measured by mass percentage: 2.0% magnesium; 1.0% copper; 0.5% silicon; 0.15% zirconium; 0.35% iron; 0.4% zinc; 0.06% chromium; 0.25% manganese; 1.8% titanium fiber; the balance is aluminum and inevitable impurities.

3. The aluminum alloy heat treatment method according to claim 1, characterized in that: The mass ratio of the titanium fiber to aluminum is 1:46-59.

4. The aluminum alloy heat treatment method according to claim 1, characterized in that: The Mg element in the component satisfies the following relationship: Ti%+0.5(Mn%)≤Mg%≤Ti%+1.5(Mn%).

5. A method for heat treatment of aluminum alloy according to any one of claims 1 to 4, characterized in that: The length of the titanium fiber is 50-150 μm.

6. An aluminum alloy, characterized in that: The aluminum alloy is prepared by the aluminum alloy heat treatment method according to any one of claims 1 to 4.