Al-Zn heat-treatment-free aluminum alloy as well as preparation method and application thereof

Abstract

The invention relates to the technical field of metal materials, and discloses an Al-Zn heat-treatment-free aluminum alloy and a preparation method and application thereof. The Al-Zn series heat treatment-free aluminum alloy is prepared from the following components in percentage by mass: 8.0 percent to 18.0 percent of Zn, 4.0 percent to 9.0 percent of Si, 0.5 percent to 4.0 percent of Cu, 0.3 percent to 1.2 percent of Mn, 0.1 percent to 0.5 percent of Zr, 0.1 percent to 0.9 percent of V, 0.1 percent to 0.4 percent of Er, 0.05 percent to 0.6 percent of Sr, 1.0 percent to 3.0 percent of TiC / TiB2 and the balance of Al and inevitable impurities. The Al-Zn heat-treatment-free aluminum alloy provided by the invention is compact in structure, fine in crystal grain, uniform in solute element distribution and excellent in mechanical property, and can meet the application requirements of the fields of automobiles and spaceflight on aluminum alloy materials.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, and in particular to an Al-Zn series heat-treatment-free aluminum alloy and a preparation method and application thereof. Background Art

[0002] The continuous development of 3C electronics, new energy vehicles and other fields has put forward higher requirements on the forming performance and quality of die-cast aluminum alloys. The plasticity of the commonly used Al-Mg-Si series alloys can meet the use requirements, but the strength performance is still unstable. In Al-Zn series alloys, the mechanical properties of the alloy can be significantly improved by reasonably regulating the content of elements such as Zn, Si, Cu in the alloy, and adding a small amount of trace elements according to demand, but the porosity and shrinkage defects in the alloy are still difficult to overcome.

[0003] The local structures of components in the automotive engine and aerospace fields are relatively complex. In the traditional die-casting process, due to the fast filling speed of the metal liquid during die-casting and the high pressure during molding, the turbulence generated by the metal liquid will hinder the timely discharge of the gas, which will cause the high-speed flowing metal liquid and the entrained gas to be compressed by huge pressure at the same time. Finally, the gas that cannot be discharged in time will solidify together with the metal liquid, seriously affecting the molding quality and performance of the casting. Die-castings are also prone to blistering and deformation during heat treatment. Summary of the invention

[0004] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, one of the purposes of the present invention is to provide an Al-Zn series aluminum alloy that does not require heat treatment; the second purpose of the present invention is to provide a method for preparing the Al-Zn series aluminum alloy that does not require heat treatment; the third purpose of the present invention is to provide an application of the Al-Zn series aluminum alloy that does not require heat treatment.

[0005] The basic principle of the present invention is described as follows:

[0006] (1) The addition ratio of Zn, Si and Cu elements has an important influence on the performance of Al-Zn alloys. The present invention adds Zn, Si and Cu elements in a specific ratio to ensure that the solute elements are dissolved into the matrix to the greatest extent, and the solute elements interact with each other to form a second phase strengthening phase, thereby improving the strength and plasticity of the alloy. Specifically, at the eutectic temperature (about 577°C), the Zn element has a large solid solubility in the matrix (31.6%). During the solidification process, 50-60% of the Zn element will be dissolved in the matrix, playing a role of solid solution strengthening. The remaining 40-50% of the Zn element will form a CuZn4 strengthening phase with the Cu element at the grain boundary (when the element ratio is (3-4):1), playing a role of second phase strengthening. At high temperatures, the solid solubility of the Cu element in the matrix is ​​5.46%. In addition, when the ratio of Cu to Al is (1-2):1, an AlCu / Al2Cu phase will be formed in the matrix, which can also play a role of second phase strengthening. When the Si content is 6-8%, the alloy strength and melt fluidity can be improved, and the casting can also be guaranteed to have good plasticity. If the Si content exceeds 10%, the plasticity of the alloy will be significantly reduced.

[0007] (2) The present invention adds trace elements of Mn, V, Zr and Er in specific proportions. Mn, V, Zr and Er are trace elements of the alloy. The introduction of trace elements can effectively improve the microstructure of the alloy and enhance the mechanical properties of the alloy. When the Mn content is 0.6-1.0%, the strength and plasticity of the alloy can reach the maximum value, and the formation of needle-shaped Fe-rich phase can be inhibited, and impurity Fe can be dissolved to form (Fe, Mn)Al6 phase. When the Mn content exceeds 1.0%, the alloy will be reduced. thermal conductivity; when the addition ratio of V, Zr and Er elements is 1:(1-2):1, (AlSi)3ZrV phase and core-shell-like Al3(Er, Zr) phase with thermal stability will be formed in the alloy matrix, which can serve as the substrate for heterogeneous nucleation of the alloy and significantly refine the grain structure. Especially when the addition ratio of Er and Zr elements is 1:(1-2.5), Al3(Er, Zr) phase plays a good dispersion strengthening role in the alloy and can significantly improve the fracture toughness of the alloy.

[0008] (3) The present invention adds TiC / TiB2 nanoparticles in a specific proportion. The in-situ generated TiC / TiB2 nanoparticles can effectively avoid the "poisoning" phenomenon caused by chemical reaction with Si element, thereby hindering the heterogeneous nucleation process of α-Al dendrites; when the content of TiC / TiB2 nanoparticles is 1.0-3.0%, they can fully interact with the matrix to play a role in refining grains. When the content of TiC / TiB2 particles is too low (less than 1.0%), the refinement effect is insufficient and the performance improvement is not obvious. When the content is too high (greater than 3.0%), clusters are easily formed in the matrix, enrichment occurs, and plasticity decreases. In addition, the interface between TiC and TiB2 particles and the matrix is ​​in a completely coherent state, and the lattice distortion produced with the matrix induces the formation of dislocations. TiC and TiB2 nanoparticles hinder the movement of dislocations. The Orowan strengthening effect can greatly improve the mechanical properties of the alloy.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] The first aspect of the present invention provides an Al-Zn series heat-treatment-free aluminum alloy, which is composed of the following components in mass percentage: Zn: 8.0-18.0%, Si: 4.0-9.0%, Cu: 0.5-4.0%, Mn: 0.3-1.2%, Zr: 0.1-0.5%, V: 0.1-0.9%, Er: 0.1-0.4%, Sr: 0.05-0.6%, TiC / TiB2: 1.0-3.0%, and the balance is Al and unavoidable impurities.

[0011] Preferably, the Al-Zn series heat-treatment-free aluminum alloy is composed of the following components in mass percentage: Al: 71.35-78.3%, Zn: 12.0-16.0%, Si: 4.0-9.0%, Cu: 0.5-2.0%, Mn: 0.6-1.2%, Zr: 0.1-0.4%, V: 0.1-0.8%, Er: 0.1-0.3%, Sr: 0.05-0.4%, TiC / TiB2: 1.0-2.0%, and unavoidable impurities <0.04%.

[0012] Further preferably, the Al-Zn series heat-treatment-free aluminum alloy is composed of the following components in mass percentage: Al: 71.35-78.3%, Zn: 13.0-15.0%, Si: 6.0-8.0%, Cu: 0.5-1.5%, Mn: 0.6-1.0%, Zr: 0.1-0.3%, V: 0.1-0.4%, Er: 0.15-0.25%, Sr: 0.05-0.2%, TiC / TiB2: 1.2-2.0%, and unavoidable impurities <0.04%.

[0013] Preferably, the unavoidable impurities include Fe, C, O and Ca.

[0014] Preferably, among the unavoidable impurities, the mass percentage content of a single impurity is less than 0.01%.

[0015] Preferably, the Al-Zn series heat-treatment-free aluminum alloy comprises the following preparation raw materials: pure aluminum, pure zinc, a master alloy, a modifier and a refiner.

[0016] Preferably, the aluminum content in the pure aluminum is ≥ 99.999wt%.

[0017] Preferably, the pure zinc has a zinc content of ≥ 99.999 wt%.

[0018] Preferably, the intermediate alloy includes Al-Si, Al-Cu, Al-Mn, Al-Zr, Al-V and Al-Er alloys; further preferably, the intermediate alloy includes Al-20%Si, Al-50%Cu, Al-20%Mn, Al-10%Zr, Al-4%V and Al-10%Er alloys.

[0019] Preferably, the modifier includes an Al-Sr modifier; further preferably, the modifier includes an Al-10%Sr modifier.

[0020] Preferably, the refiner comprises Al-TiC / TiB2 nanoparticles; further preferably, the refiner comprises Al-30%TiC / TiB2 nanoparticles.

[0021] The second aspect of the present invention provides a method for preparing the Al-Zn series heat-treatment-free aluminum alloy according to the first aspect of the present invention, comprising the following steps:

[0022] S1, adding pure aluminum, master alloy and pure zinc in sequence and smelting to obtain alloy liquid;

[0023] S2, adding a modifier and a refiner to the alloy liquid in sequence and refining the alloy liquid to obtain a refined liquid;

[0024] S3, stirring, pouring and die-casting the refined liquid to obtain the Al-Zn series heat-treatment-free aluminum alloy.

[0025] Preferably, in step S1, the smelting process conditions include at least one of the following:

[0026] 1) The smelting temperature after adding pure aluminum is 710-800° C., and the smelting time is 1-4 hours;

[0027] 2) the smelting temperature after adding the master alloy is 730-790° C., and the smelting time is 0.5-2.5 h;

[0028] 3) The smelting temperature after adding pure zinc is 630-730° C., and the smelting time is 1-2 hours.

[0029] Further preferably, in step S1, the smelting process conditions include at least one of the following:

[0030] 1) The smelting temperature after adding pure aluminum is 740-790° C., and the smelting time is 1-3 hours;

[0031] 2) the smelting temperature after adding the master alloy is 740-780° C., and the smelting time is 0.5-2 h;

[0032] 3) The smelting temperature after adding pure zinc is 650-720° C., and the smelting time is 0.2-1.5 h.

[0033] More preferably, in step S1, the smelting process conditions include at least one of the following:

[0034] 1) The smelting temperature after adding pure aluminum is 750-780° C., and the smelting time is 1.5-2.5 h;

[0035] 2) the smelting temperature after adding the master alloy is 745-760° C., and the smelting time is 1-1.5 h;

[0036] 3) The smelting temperature after adding pure zinc is 670-700° C., and the smelting time is 0.3-0.8 h.

[0037] Preferably, in step S1, when 40-60wt% of the pure aluminum is melted, an intermediate alloy is added.

[0038] Preferably, in step S1, pure zinc is added when the pure aluminum and the master alloy are completely melted.

[0039] Preferably, in step S2, the refining process conditions include at least one of the following:

[0040] 1) The refining temperature after adding the modifier is 630-750° C. and the refining time is 0.1-1h;

[0041] 2) The refining temperature after adding the refiner is 690-760°C, and the refining time is 0.1-1h.

[0042] Further preferably, in step S2, the refining process conditions include at least one of the following:

[0043] 1) The refining temperature after adding the modifier is 660-740° C., and the refining time is 0.1-0.5 h;

[0044] 2) The refining temperature after adding the refiner is 700-750°C, and the refining time is 0.1-0.5h.

[0045] More preferably, in step S2, the refining process conditions include at least one of the following:

[0046] 1) The refining temperature after adding the modifier is 690-730° C., and the refining time is 0.2-0.4 h;

[0047] 2) The refining temperature after adding the refiner is 730-740°C, and the refining time is 0.2-0.4h.

[0048] Preferably, in step S3, the stirring method includes ultrasonic vibration stirring.

[0049] Preferably, the parameters of the ultrasonic vibration stirring include at least one of the following:

[0050] 1) The power of the ultrasonic vibration is 500-3000W;

[0051] 2) The resonant frequency of the ultrasonic vibration is 15-35kHz;

[0052] 3) The ultrasonic vibration time is 3-10 minutes.

[0053] Further preferably, the parameters of the ultrasonic vibration stirring include at least one of the following:

[0054] 1) The power of the ultrasonic vibration is 1000-2500W;

[0055] 2) The resonant frequency of the ultrasonic vibration is 20-30kHz;

[0056] 3) The ultrasonic vibration time is 3-8 minutes.

[0057] Specifically, ultrasonic vibration stirring of the refined liquid can give full play to the cavitation effect, evenly disperse the nanoparticle refiner in the melt, and achieve a better heterogeneous nucleation effect during the solidification process. The parameters of ultrasonic vibration stirring will have a great impact on the process effect. If the power is too large or the frequency is too high, it will easily lead to huge instantaneous pressure, causing liquid splashing and gas entrapment; if the power is too small or the frequency is too low, it will lead to uneven vibration stirring, affecting the distribution of the refiner.

[0058] Preferably, in the step S3, after the stirring is completed, the step of skimming and standing the refined liquid is also included.

[0059] Preferably, the standing time is 3-25 min; further preferably, the standing time is 4-16 min; further preferably, the standing time is 8-15 min.

[0060] Preferably, in step S3, the pouring process conditions include at least one of the following:

[0061] 1) The pouring temperature is 660-780°C;

[0062] 2) The pouring speed is 0.4-1.6 m / s.

[0063] Further preferably, in step S3, the pouring process conditions include at least one of the following:

[0064] 1) The pouring temperature is 690-750°C;

[0065] 2) The pouring speed is 0.5-1.4 m / s.

[0066] More preferably, in step S3, the pouring process conditions include at least one of the following:

[0067] 1) The pouring temperature is 700-730°C;

[0068] 2) The pouring speed is 0.6-1.0 m / s.

[0069] Preferably, the pouring process uses a mechanical automatic tilting smelting furnace, and the refined liquid is poured into a die-casting mold after being allowed to stand. A pouring cup is provided at the upper end of the die-casting mold.

[0070] Specifically, by selecting a lower pouring temperature and a higher pouring speed during the die casting process, the supercooling required for the solidification of the alloy and the time of contact with air can be reduced, thereby avoiding defects such as shrinkage cavities, shrinkage porosity, air holes and sand adhesion in the casting due to excessively high pouring temperatures, or defects such as insufficient pouring due to poor alloy fluidity due to excessively low pouring temperatures. In addition, the pouring speed of the present invention can ensure that the alloy liquid quickly and completely fills the mold cavity, thereby avoiding defects such as cold shut or insufficient pouring during the pouring process.

[0071] Preferably, in step S3, the die-casting process conditions include at least one of the following:

[0072] 1) The die casting is vacuum die casting, and the vacuum degree is 1-50kPa;

[0073] 2) The die-casting injection speed is 4-6.5 m / s;

[0074] 3) The injection pressure of the die casting is 100-600MPa;

[0075] 4) The die casting mold temperature is 100-300°C.

[0076] Further preferably, in step S3, the die-casting process conditions include at least one of the following:

[0077] 1) The die casting is vacuum die casting, and the vacuum degree is 5-30kPa;

[0078] 2) The die-casting injection speed is 4-6 m / s;

[0079] 3) The injection pressure of the die casting is 200-400MPa;

[0080] 4) The die casting mold temperature is 100-200°C.

[0081] Specifically, using a relatively high vacuum degree during the die-casting process can prevent the alloy liquid from being drawn into gas during the stirring process, which may cause defects such as pores in the ingot. For the die-casting injection pressure, if it is too small, the gas drawn into the casting may not be discharged, while if it is too large, the casting may have excessive residual stress, which is not conducive to molding. Therefore, the pressure must be appropriate.

[0082] Preferably, in the step S3, a pressure-maintaining step is further included after the die-casting.

[0083] Preferably, the pressure holding time is 1-15 minutes; further preferably, the pressure holding time is 2-12 minutes; further preferably, the pressure holding time is 5-10 minutes.

[0084] The basic principle of the preparation method of Al-Zn series heat-treatment-free aluminum alloy is described as follows:

[0085] (1) The present invention ensures that pure aluminum and pure zinc are fully melted by smelting pure aluminum, master alloy, and pure zinc in batches, and that solute elements are evenly distributed in the melt without overburning.

[0086] (2) By using in-situ TiC / TiB2 nanoparticles for refinement, the initial solidification temperature of the aluminum liquid can be significantly increased and the supercooling required for solidification can be reduced;

[0087] (3) By controlling the smelting temperature and time, the smelting efficiency can be improved and the product quality can be improved;

[0088] (4) The die casting method under vacuum conditions can significantly improve the cleanliness and density of the alloy, eliminate structural defects such as pores and inclusions, ensure that there are no inclusions in the structure of the alloy casting, and avoid the adverse effects of inclusions on the alloy properties, thereby preparing an aluminum alloy with good tensile strength, yield strength and elongation.

[0089] The third aspect of the present invention provides the application of the Al-Zn series heat-treatment-free aluminum alloy described in the first aspect of the present invention in the automotive and aerospace fields.

[0090] Compared with the prior art, the present invention has the following beneficial effects:

[0091] 1) The Al-Zn series heat-treatment-free aluminum alloy provided by the present invention ensures that the solute elements are dissolved into the matrix to the greatest extent by regulating the content range of Zn, Si, and Cu elements, and forms a second phase strengthening phase by utilizing the interaction between the solute elements, thereby improving the strength and plasticity of the alloy; by regulating the content range of trace alloying elements such as Mn, Zr, V, and Er, the microstructure of the alloy is improved and the mechanical properties of the alloy are enhanced; by regulating the content range of nanoparticles TiC / TiB2, the grains of the alloy are refined and the mechanical properties are improved; the present invention obtains an aluminum alloy with dense structure, fine grains, uniform distribution of solute elements, and few casting defects by regulating the organization of the main alloying elements and in-situ nanoparticles;

[0092] 2) The preparation method of the Al-Zn series heat-treatment-free aluminum alloy provided by the present invention adopts a batch smelting method to make the solute elements evenly distributed; by controlling the smelting temperature and time of each batch, the smelting efficiency is improved and the product quality is improved; by ultrasonic vibration stirring of the refined liquid, a melt with uniform composition and no impurities is obtained; by adopting a vacuum die-casting process, high-quality die-casting parts with high cleanliness and density and few structural defects such as pores are obtained;

[0093] 3) After the Al-Zn series heat-treatment-free aluminum alloy provided by the present invention is die-cast, the tensile strength of the aluminum alloy ingot reaches 388MPa, the yield strength reaches 272MPa, the elongation reaches 6.2%, and the defects such as pores and shrinkage are few. The product quality is high and can meet the performance requirements of the automotive and aerospace fields for heat-treatment-free aluminum alloy die-castings. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Figure 1 The microstructure of the Al-Zn series heat-treatment-free aluminum alloy ingot prepared in Example 1;

[0095] Figure 2 The microstructure of the Al-Zn aluminum alloy ingot without heat treatment prepared in Comparative Example 1;

[0096] Figure 3 The microstructure of the Al-Zn aluminum alloy ingot without heat treatment prepared in Comparative Example 3;

[0097] Figure 4 This is the microstructure diagram of the Al-Zn series heat-treatment-free aluminum alloy ingot prepared in Comparative Example 4. DETAILED DESCRIPTION

[0098] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0099] Example 1

[0100] In this embodiment, an Al-Zn series heat-treatment-free aluminum alloy is prepared. The composition of the Al-Zn series heat-treatment-free aluminum alloy is shown in Table 1:

[0101] Table 1 Composition and content of Al-Zn series heat-treatment-free aluminum alloy in Example 1

[0102] Components Content (wt%) Components Content (wt%) Zn 13.5 Sr 0.08 Si 6.5 <![CDATA[TiC / TiB2]]> 1.5 Cu 0.9 Al 75.80 Mn 1.0 Fe ＜0.01 Zr 0.2 C ＜0.01 V 0.3 O ＜0.01 Er 0.2 Ca ＜0.01

[0103] The raw materials for preparing Al-Zn series heat-treatment-free aluminum alloy are:

[0104] Pure aluminum ingots (aluminum content ≥ 99.999wt%, industrial grade), pure zinc ingots (zinc content ≥ 99.999wt%, industrial grade);

[0105] Master alloy: Al-20%Si, Al-50%Cu, Al-20%Mn, Al-10%Zr, Al-4%V and Al-10%Er alloys;

[0106] Modifier: Al-10% Sr modifier;

[0107] Refining agent: Al-30% TiC / TiB2 nanoparticles.

[0108] The preparation steps of Al-Zn series heat-treatment-free aluminum alloy are as follows:

[0109] S11. According to the formula of Al-Zn series heat-treatment-free aluminum alloy, add pure aluminum ingot into a resistance furnace, heat it to 770°C, and keep it warm for 2 hours. At this time, the pure aluminum ingot is half melted, add the intermediate alloy, cool it to 750°C, and keep it warm for 1.5 hours. After the pure aluminum ingot and the intermediate alloy are completely melted, cool it to 690°C, add the pure zinc ingot, and smelt it for 0.5 hours to obtain alloy liquid;

[0110] S21, subjecting the alloy liquid in S11 to modification and refinement treatment, heating it to 720°C, adding a modifier, stirring it fully, and keeping it warm for 0.3h, then heating it to 735°C, adding a refiner, and keeping it warm for 0.3h to obtain a refined liquid;

[0111] S31. The refined liquid in S21 is subjected to ultrasonic vibration stirring (vibration power of 1000 W, resonance frequency of 20 kHz, vibration time of 5 min). After the vibration is completed, the slag is removed, and the mixture is poured and die-cast after standing for 10 min. The entire die-casting mold is sealed with a vacuum cover. The refined liquid is poured into the pressure chamber at a speed of 1.0 m / s at 730 ° C. The pressure chamber is sealed with an injection punch. The vacuum degree is controlled at 20 kPa, the high injection speed is 4 m / s, the injection pressure is 300 MPa, the mold temperature is 150 ° C., and the holding time is 5 min. Al-Zn series aluminum alloy ingots free of heat treatment are obtained.

[0112] Example 2

[0113] In this embodiment, an Al-Zn series heat-treatment-free aluminum alloy is prepared. The composition of the Al-Zn series heat-treatment-free aluminum alloy is shown in Table 2:

[0114] Table 2 Composition and content of Al-Zn series heat-treatment-free aluminum alloy in Example 2

[0115] Components Content (wt%) Components Content (wt%) Zn 13.5 Sr 0.08 Si 6.5 <![CDATA[TiC / TiB2]]> 1.5 Cu 0.9 Al 75.79 Mn 1.0 Fe ＜0.01 Zr 0.2 C ＜0.01 V 0.3 O ＜0.01 Er 0.2 Ca ＜0.01

[0116] The raw materials for preparing Al-Zn series heat-treatment-free aluminum alloy are:

[0117] Pure aluminum ingots (aluminum content ≥ 99.999wt%, industrial grade), pure zinc ingots (zinc content ≥ 99.999wt%, industrial grade);

[0118] Master alloy: Al-20%Si, Al-50%Cu, Al-20%Mn, Al-10%Zr, Al-4%V and Al-10%Er alloys;

[0119] Modifier: Al-10% Sr modifier;

[0120] Refining agent: Al-30% TiC / TiB2 nanoparticles.

[0121] The preparation steps of Al-Zn series heat-treatment-free aluminum alloy are as follows:

[0122] S11. According to the formula of Al-Zn series heat-treatment-free aluminum alloy, add pure aluminum ingot into a resistance furnace, heat it to 770°C, and keep it warm for 2 hours. At this time, the pure aluminum ingot is half melted, add the intermediate alloy, cool it to 750°C, and keep it warm for 1.5 hours. After the pure aluminum ingot and the intermediate alloy are completely melted, cool it to 690°C, add the pure zinc ingot, and smelt it for 0.5 hours to obtain alloy liquid;

[0123] S21, subjecting the alloy liquid in S11 to modification and refinement treatment, heating it to 720°C, adding a modifier, stirring it fully, and keeping it warm for 0.3h, then heating it to 735°C, adding a refiner, and keeping it warm for 0.3h to obtain a refined liquid;

[0124] S31. The refined liquid in S21 is subjected to ultrasonic vibration stirring (vibration power of 1000 W, resonance frequency of 20 kHz, vibration time of 5 min). After the vibration is completed, the slag is removed, and the mixture is poured and die-cast after standing for 10 min. The entire die-casting mold is sealed with a vacuum cover. The refined liquid is poured into the pressure chamber at a speed of 1.0 m / s at 730 ° C. The pressure chamber is sealed with an injection punch. The vacuum degree is controlled at 5 kPa, the high shot injection speed is 4 m / s, the injection pressure is 300 MPa, the mold temperature is 150 ° C., and the holding time is 5 min. Al-Zn series aluminum alloy ingots free of heat treatment are obtained.

[0125] Example 3

[0126] In this embodiment, an Al-Zn series heat-treatment-free aluminum alloy is prepared. The composition of the Al-Zn series heat-treatment-free aluminum alloy is shown in Table 3:

[0127] Table 3 Composition and content of Al-Zn series heat-treatment-free aluminum alloy in Example 3

[0128]

[0129]

[0130] The raw materials for preparing Al-Zn series heat-treatment-free aluminum alloy are:

[0131] Pure aluminum ingots (aluminum content ≥ 99.999wt%, industrial grade), pure zinc ingots (zinc content ≥ 99.999wt%, industrial grade);

[0132] Master alloy: Al-20%Si, Al-50%Cu, Al-20%Mn, Al-10%Zr, Al-4%V and Al-10%Er alloys;

[0133] Modifier: Al-10% Sr modifier;

[0134] Refining agent: Al-30% TiC / TiB2 nanoparticles.

[0135] The preparation steps of Al-Zn series heat-treatment-free aluminum alloy are as follows:

[0136] S11. According to the formula of Al-Zn series heat-treatment-free aluminum alloy, add pure aluminum ingot into a resistance furnace, heat it to 770°C, and keep it warm for 2 hours. At this time, the pure aluminum ingot is half melted, add the intermediate alloy, cool it to 750°C, and keep it warm for 1.5 hours. After the pure aluminum ingot and the intermediate alloy are completely melted, cool it to 690°C, add the pure zinc ingot, and smelt it for 0.5 hours to obtain alloy liquid;

[0137] S21, subjecting the alloy liquid in S11 to modification and refinement treatment, heating it to 720°C, adding a modifier, stirring it fully, and keeping it warm for 0.3h, then heating it to 735°C, adding a refiner, and keeping it warm for 0.3h to obtain a refined liquid;

[0138] S31. The refined liquid in S21 is subjected to ultrasonic vibration stirring (vibration power of 1000 W, resonance frequency of 20 kHz, vibration time of 5 min). After the vibration is completed, the slag is removed, and the mixture is poured and die-cast after standing for 10 min. The entire die-casting mold is sealed with a vacuum cover. The refined liquid is poured into the pressure chamber at a speed of 1.0 m / s at 730 ° C. The pressure chamber is sealed with an injection punch. The vacuum degree is controlled at 20 kPa, the high injection speed is 4 m / s, the injection pressure is 300 MPa, the mold temperature is 150 ° C., and the holding time is 5 min. Al-Zn series aluminum alloy ingots free of heat treatment are obtained.

[0139] Example 4

[0140] In this embodiment, an Al-Zn series heat-treatment-free aluminum alloy is prepared. The composition of the Al-Zn series heat-treatment-free aluminum alloy is shown in Table 4:

[0141] Table 4 Composition and content of Al-Zn series heat-treatment-free aluminum alloy in Example 4

[0142]

[0143]

[0144] The raw materials for preparing Al-Zn series heat-treatment-free aluminum alloy are:

[0145] Pure aluminum ingots (aluminum content ≥ 99.999wt%, industrial grade), pure zinc ingots (zinc content ≥ 99.999wt%, industrial grade);

[0146] Master alloy: Al-20%Si, Al-50%Cu, Al-20%Mn, Al-10%Zr, Al-4%V and Al-10%Er alloys;

[0147] Modifier: Al-10% Sr modifier;

[0148] Refining agent: Al-30% TiC / TiB2 nanoparticles.

[0149] The preparation steps of Al-Zn series heat-treatment-free aluminum alloy are as follows:

[0150] S11. According to the formula of Al-Zn series heat-treatment-free aluminum alloy, add pure aluminum ingot into a resistance furnace, heat it to 770°C, and keep it warm for 2 hours. At this time, the pure aluminum ingot is half melted, add the intermediate alloy, cool it to 750°C, and keep it warm for 1.5 hours. After the pure aluminum ingot and the intermediate alloy are completely melted, cool it to 690°C, add the pure zinc ingot, and smelt it for 0.5 hours to obtain alloy liquid;

[0151] S21, subjecting the alloy liquid in S11 to modification and refinement treatment, heating it to 720°C, adding a modifier, stirring it fully, and keeping it warm for 0.3h, then heating it to 735°C, adding a refiner, and keeping it warm for 0.3h to obtain a refined liquid;

[0152] S31. The refined liquid in S21 is subjected to ultrasonic vibration stirring (vibration power of 2000 W, resonance frequency of 25 kHz, vibration time of 8 min). After the vibration is completed, the slag is removed, and the mixture is poured and die-cast after standing for 10 min. The entire die-casting mold is sealed with a vacuum cover. The refined liquid is poured into the pressure chamber at a speed of 1.0 m / s at 730 ° C. The pressure chamber is sealed with an injection punch. The vacuum degree is controlled at 20 kPa, the high shot injection speed is 4 m / s, the injection pressure is 300 MPa, the mold temperature is 150 ° C., and the holding time is 5 min. Al-Zn series aluminum alloy ingots free of heat treatment are obtained.

[0153] Comparative Example 1

[0154] In this comparative example, an Al-Zn series heat-treatment-free aluminum alloy is prepared. The composition of the Al-Zn series heat-treatment-free aluminum alloy is shown in Table 5:

[0155] Table 5 Composition and content of Al-Zn series heat-treatment-free aluminum alloy in Comparative Example 1

[0156]

[0157]

[0158] The raw materials for preparing Al-Zn series heat-treatment-free aluminum alloy are:

[0159] Pure aluminum ingots (aluminum content ≥ 99.999wt%, industrial grade), pure zinc ingots (zinc content ≥ 99.999wt%, industrial grade);

[0160] Master alloy: Al-20%Si and Al-50%Cu alloys.

[0161] The preparation steps of Al-Zn series heat-treatment-free aluminum alloy are as follows:

[0162] S11. According to the formula of Al-Zn series heat-treatment-free aluminum alloy, add pure aluminum ingot into a resistance furnace, heat it to 770°C, and keep it warm for 2 hours. At this time, the pure aluminum ingot is half melted, add the intermediate alloy, cool it to 750°C, and keep it warm for 1.5 hours. After the pure aluminum ingot and the intermediate alloy are completely melted, cool it to 690°C, add the pure zinc ingot, and smelt it for 0.5 hours to obtain alloy liquid;

[0163] S31. The alloy liquid in S11 is subjected to ultrasonic vibration stirring (vibration power of 1000 W, resonance frequency of 20 kHz, vibration time of 5 min). After the vibration is completed, the slag is removed, and the mixture is poured and die-cast after standing for 10 min. The entire die-casting mold is sealed with a vacuum hood. The refined liquid is poured into the pressure chamber at a speed of 1.0 m / s at 730 ° C. The pressure chamber is sealed with an injection punch. The vacuum degree is controlled at 20 kPa, the high shot injection speed is 4 m / s, the injection pressure is 300 MPa, the mold temperature is 150 ° C., and the holding time is 5 min. Al-Zn series aluminum alloy ingots that do not require heat treatment are obtained.

[0164] Comparative Example 2

[0165] In this comparative example, an Al-Zn series heat-treatment-free aluminum alloy is prepared. The composition of the Al-Zn series heat-treatment-free aluminum alloy is shown in Table 6:

[0166] Table 6 Composition and content of Al-Zn series heat-treatment-free aluminum alloy in comparative example 2

[0167] Components Content (wt%) Components Content (wt%) Zn 6.5 Sr 0.02 Si 4.5 <![CDATA[TiC / TiB2]]> 0.5 Cu 0.4 Al 87.25 Mn 0.4 Fe ＜0.01 Zr 0.2 C ＜0.01 V 0.1 O ＜0.01 Er 0.1 Ca ＜0.01

[0168] The raw materials for preparing Al-Zn series heat-treatment-free aluminum alloy are:

[0169] Pure aluminum ingots (aluminum content ≥ 99.999wt%, industrial grade), pure zinc ingots (zinc content ≥ 99.999wt%, industrial grade);

[0170] Master alloy: Al-20%Si, Al-50%Cu, Al-20%Mn, Al-10%Zr, Al-4%V and Al-10%Er alloys;

[0171] Modifier: Al-10% Sr modifier;

[0172] Refining agent: Al-30% TiC / TiB2 nanoparticles.

[0173] The preparation steps of Al-Zn series heat-treatment-free aluminum alloy are as follows:

[0174] S11. According to the formula of Al-Zn series heat-treatment-free aluminum alloy, add pure aluminum ingot into a resistance furnace, heat it to 770°C, and keep it warm for 2 hours. At this time, the pure aluminum ingot is half melted, add the intermediate alloy, cool it to 750°C, and keep it warm for 1.5 hours. After the pure aluminum ingot and the intermediate alloy are completely melted, cool it to 690°C, add the pure zinc ingot, and smelt it for 0.5 hours to obtain alloy liquid;

[0175] S21, subjecting the alloy liquid in S11 to modification and refinement treatment, heating it to 720°C, adding a modifier, stirring it fully, and keeping it warm for 0.3h, then heating it to 735°C, adding a refiner, and keeping it warm for 0.3h to obtain a refined liquid;

[0176] S31. The refined liquid in S21 is subjected to ultrasonic vibration stirring (vibration power of 1000 W, resonance frequency of 20 kHz, vibration time of 5 min). After the vibration is completed, the slag is removed, and the mixture is poured and die-cast after standing for 10 min. The entire die-casting mold is sealed with a vacuum cover. The refined liquid is poured into the pressure chamber at a speed of 1.0 m / s at 730 ° C. The pressure chamber is sealed with an injection punch. The vacuum degree is controlled at 20 kPa, the high injection speed is 4 m / s, the injection pressure is 300 MPa, the mold temperature is 150 ° C., and the holding time is 5 min. Al-Zn series aluminum alloy ingots free of heat treatment are obtained.

[0177] Comparative Example 3

[0178] In this comparative example, an Al-Zn series heat-treatment-free aluminum alloy is prepared. The composition of the Al-Zn series heat-treatment-free aluminum alloy is shown in Table 7:

[0179] Table 7 Composition and content of Al-Zn series heat-treatment-free aluminum alloy in comparative example 3

[0180] Components Content (wt%) Components Content (wt%) Zn 13.5 Sr 0.08 Si 6.5 <![CDATA[TiC / TiB2]]> 1.5 Cu 0.9 Al 75.81 Mn 1.0 Fe ＜0.01 Zr 0.2 C ＜0.01 V 0.3 O ＜0.01 Er 0.2 Ca ＜0.01

[0181] The raw materials for preparing Al-Zn series heat-treatment-free aluminum alloy are:

[0182] Pure aluminum ingots (aluminum content ≥ 99.999wt%, industrial grade), pure zinc ingots (zinc content ≥ 99.999wt%, industrial grade);

[0183] Master alloy: Al-20%Si, Al-50%Cu, Al-20%Mn, Al-10%Zr, Al-4%V and Al-10%Er alloys;

[0184] Modifier: Al-10% Sr modifier;

[0185] Refining agent: Al-30% TiC / TiB2 nanoparticles.

[0186] The preparation steps of Al-Zn series heat-treatment-free aluminum alloy are as follows:

[0187] S11. According to the formula of Al-Zn series heat-treatment-free aluminum alloy, add pure aluminum ingot into a resistance furnace, heat it to 770°C, and keep it warm for 2 hours. At this time, the pure aluminum ingot is half melted, add the intermediate alloy, cool it to 750°C, and keep it warm for 1.5 hours. After the pure aluminum ingot and the intermediate alloy are completely melted, cool it to 690°C, add the pure zinc ingot, and smelt it for 0.5 hours to obtain alloy liquid;

[0188] S21, subjecting the alloy liquid in S11 to modification and refinement treatment, heating it to 720°C, adding a modifier, stirring it fully, and keeping it warm for 0.3h, then heating it to 735°C, adding a refiner, and keeping it warm for 0.3h to obtain a refined liquid;

[0189] S31. The refined liquid in S21 is mechanically stirred, and the slag is removed after the stirring is completed. After standing for 10 minutes, it is poured and die-casted. The entire die-casting mold is sealed with a vacuum cover. The refined liquid is poured into the pressure chamber at a speed of 1.0 m / s at 730°C, and the pressure chamber is sealed with an injection punch. The vacuum degree is controlled at 20 kPa, the high injection speed is 4 m / s, the injection pressure is 300 MPa, the mold temperature is 150°C, and the holding time is 5 minutes to obtain Al-Zn series heat-treatment-free aluminum alloy ingots.

[0190] Comparative Example 4

[0191] In this comparative example, an Al-Zn series heat-treatment-free aluminum alloy is prepared. The composition of the Al-Zn series heat-treatment-free aluminum alloy is shown in Table 8:

[0192] Table 8 Composition and content of Al-Zn series heat-treatment-free aluminum alloy in comparative example 4

[0193] Components Content (wt%) Components Content (wt%) Zn 14.5 Sr 0.2 Si 8.0 <![CDATA[TiC / TiB2]]> 2.0 Cu 1.5 Al 71.83 Mn 1.0 Fe ＜0.01 Zr 0.3 C ＜0.01 V 0.4 O ＜0.01 Er 0.25 Ca ＜0.01

[0194] The raw materials for preparing Al-Zn series heat-treatment-free aluminum alloy are:

[0195] Pure aluminum ingots (aluminum content ≥ 99.999wt%, industrial grade), pure zinc ingots (zinc content ≥ 99.999wt%, industrial grade);

[0196] Master alloy: Al-20%Si, Al-50%Cu, Al-20%Mn, Al-10%Zr, Al-4%V and Al-10%Er alloys;

[0197] Modifier: Al-10% Sr modifier;

[0198] Refining agent: Al-30% TiC / TiB2 nanoparticles.

[0199] The preparation steps of Al-Zn series heat-treatment-free aluminum alloy are as follows:

[0200] S11. According to the formula of Al-Zn series heat-treatment-free aluminum alloy, add pure aluminum ingot into a resistance furnace, heat it to 770°C, and keep it warm for 2 hours. At this time, the pure aluminum ingot is half melted, add the intermediate alloy, cool it to 750°C, and keep it warm for 1.5 hours. After the pure aluminum ingot and the intermediate alloy are completely melted, cool it to 690°C, add the pure zinc ingot, and smelt it for 0.5 hours to obtain alloy liquid;

[0201] S21, subjecting the alloy liquid in S11 to modification and refinement treatment, heating it to 720°C, adding a modifier, stirring it fully, and keeping it warm for 0.3h, then heating it to 735°C, adding a refiner, and keeping it warm for 0.3h to obtain a refined liquid;

[0202] S31. The refined liquid in S21 is subjected to ultrasonic vibration stirring (vibration power of 1000 W, resonance frequency of 20 kHz, vibration time of 5 min). After the vibration is completed, the slag is removed, and after standing for 10 min, it is poured and die-casted. The entire die-casting mold is sealed with a vacuum cover. The refined liquid is poured into the pressure chamber at a speed of 1.0 m / s at 700 ° C. The pressure chamber is sealed with an injection punch. The vacuum is not started. The high injection speed is 4 m / s, the injection pressure is 100 MPa, the mold temperature is 100 ° C., and the holding time is 5 min to obtain an Al-Zn series heat-treatment-free aluminum alloy ingot.

[0203] Performance Testing

[0204] 1. The microstructure of the Al-Zn series heat-treatment-free aluminum alloy ingots prepared in Example 1, Comparative Example 1, Comparative Example 3 and Comparative Example 4 was observed using a metallographic microscope:

[0205] Figure 1 The microstructure of the Al-Zn aluminum alloy ingot without heat treatment prepared in Example 1 is shown in FIG. Figure 1 It can be seen that the Al-Zn series heat-treatment-free aluminum alloy in Example 1 has a dense structure, fine grains, and uniform distribution of solute elements.

[0206] Figure 2 The microstructure of the Al-Zn aluminum alloy ingot without heat treatment prepared in Comparative Example 1 is shown in FIG. Figure 2 It can be seen that the Al-Zn series heat-treatment-free aluminum alloy in Comparative Example 1 has a coarse structure, uneven grain distribution, and coarse α-Al dendrites. This is because no trace alloying elements are added in Comparative Example 1, and a second phase containing trace alloying elements cannot be formed in the alloy matrix, and the effect of refining the grains cannot be played.

[0207] Figure 3 The microstructure of the Al-Zn aluminum alloy ingot without heat treatment prepared in Comparative Example 3 is shown in FIG. Figure 3It can be seen that the Al-Zn series heat-treatment-free aluminum alloy in Comparative Example 3 has serious solute element segregation and enrichment. This is because Comparative Example 3 does not use ultrasonic vibration stirring, resulting in uneven distribution of nanoparticles and solute elements in the melt, and segregation is very likely to occur under the effect of rapid cooling during the die-casting process.

[0208] Figure 4 The microstructure of the Al-Zn aluminum alloy ingot without heat treatment prepared in Comparative Example 4 is shown in FIG. Figure 4 It can be seen that the Al-Zn series heat-treatment-free aluminum alloy in Comparative Example 4 has more pores and inclusion defects. This is because the die-casting process parameters in the preparation process of Comparative Example 4 are not within the scope of the present invention, and it is not carried out in a vacuum atmosphere, resulting in low cleanliness and density of the alloy.

[0209] It can be seen that the present invention simultaneously adds Zn, Si, Cu, and trace alloying elements Mn, Zr, V and Er in specific proportions, and obtains a melt with uniform composition and no impurities by introducing in-situ TiC / TiB2 nanoparticles combined with ultrasonic vibration stirring. Combined with the vacuum die-casting process, the obtained alloy ingot has a dense structure, fine grains, and uniform distribution of solute elements.

[0210] 2. Mechanical properties tests were performed on the Al-Zn series heat-treatment-free aluminum alloy ingots prepared in Examples 1-4 and Comparative Examples 1-4:

[0211] The tensile test was completed on a WGW-100H universal material testing machine. The specific test method is as follows:

[0212] 1) The tensile strength is tested according to GB-T228-2002 "Room Temperature Tensile Test Method for Metallic Materials";

[0213] 2) The yield strength is tested in accordance with GB-T228-2002 "Room Temperature Tensile Test Method for Metallic Materials";

[0214] 3) The elongation is tested with reference to GBT 17737.308-2018 "Coaxial Communication Cable" Part 1-308: Mechanical Test Methods for Tensile Strength and Elongation Test of Copper Clad Metal.

[0215] Table 9 Mechanical properties test results of Al-Zn series heat-free aluminum alloy ingots prepared in Examples 1-4 and Comparative Examples 1-4

[0216] Example / Comparative Example Tensile strength / MPa Yield strength / MPa Elongation / % Example 1 378 264 6.5 Example 2 388 272 6.2 Example 3 364 255 5.9 Example 4 370 267 6.0 Comparative Example 1 324 201 7.6 Comparative Example 2 336 220 4.8 Comparative Example 3 319 229 4.9 Comparative Example 4 330 231 5.1

[0217] Table 9 shows the mechanical property test results of the Al-Zn series heat-treatment-free aluminum alloy ingots prepared in Examples 1-4 and Comparative Examples 1-4. It can be seen from Table 9 that the tensile strength of the Al-Zn series heat-treatment-free aluminum alloy ingots in Examples 1-4 is 364-388 MPa, the yield strength is 255-272 MPa, and the elongation is 5.9-6.5%. The alloy has good tensile strength, yield strength and elongation, and excellent mechanical properties.

[0218] Since no trace alloying elements were added to Comparative Example 1, the tensile strength of the alloy was 324 MPa, the yield strength was 201 MPa, and the elongation was 7.6%. The mechanical properties were significantly worse than those of Example 1, indicating that the addition of alloy trace elements plays an important role in improving the mechanical properties of the alloy.

[0219] The addition amount of alloying elements in Comparative Example 2 is not within the scope provided by the present invention. The tensile strength of the alloy is 336 MPa, the yield strength is 220 MPa, and the elongation is 4.8%. The mechanical properties are significantly worse than those of Example 1, indicating that alloying elements need to be added in a specific proportion to better improve the mechanical properties of the alloy.

[0220] In Comparative Example 3, after the nanoparticle refiner was added, ultrasonic vibration stirring was not applied to the melt for treatment. The tensile strength of the alloy was 319 MPa, the yield strength was 229 MPa, and the elongation was 4.9%. The mechanical properties were significantly worse than those of Example 1, indicating that ultrasonic vibration stirring plays an important role in the uniform distribution of nanoparticles and solute elements, and is beneficial to improving the mechanical properties of the alloy.

[0221] The die-casting process conditions of Comparative Example 4 are not within the scope provided by the present invention. The tensile strength of the alloy is 330 MPa, the yield strength is 231 MPa, the elongation is 5.1%, and the mechanical properties are significantly worse than those of Example 3. This shows that the use of a die-casting process with specific parameters can obtain castings with dense structure, few defects such as pores and inclusions, which is beneficial to improving the mechanical properties of the alloy.

[0222] The present invention adds Zn, Si and Cu elements in specific proportions, coordinates and controls, exerts the effects of solid solution strengthening and second phase strengthening, and improves the mechanical properties of the alloy; introduces Mn, V, Zr and Er trace alloying elements in specific proportions, so that the Mn element hinders the growth of recrystallized grains by forming Al6Mn compound dispersed recrystallization dispersed particles, and simultaneously forms (Fe, Mn)Al6 to reduce the harmful effects of Fe-rich phases; V, Zr and Er elements are used to effectively increase the nucleation temperature and nucleation supercooling of primary α-Al, and the recrystallization temperature of the alloy is increased by forming Si2V phase, Al3Zr phase, Zr2Si phase and Al3Er phase, and the dispersion strengthening effect is exerted by forming (AlSi)3ZrV phase and core-shell Al3(Er, Zr) phase; in-situ self-generated TiC / TiB2 nanoparticles are selected as refiners, which simultaneously play the role of refining grains and improving the mechanical properties of the alloy.

[0223] The present invention adjusts the content range of Zn, Si, Cu and trace alloy elements and nano-particle refiners, and combines the optimized preparation process to obtain good elongation on the basis of ensuring the strength of the alloy. The obtained Al-Zn series heat-treatment-free aluminum alloy has a dense structure, fine grains, no defects such as pores and shrinkage, and high product quality, which can meet the high requirements of the automotive and aerospace fields for aluminum alloy materials.

Claims

1. An Al-Zn series heat-treatment-free aluminum alloy, characterized in that: The following components are present in percentage by weight composition: Zn: 8.0-18.0%, Si: 4.0-9.0%, Cu: 0.5-4.0%, Mn: 0.3-1.2%, Zr: 0.1-0.5%, V: 0.1-0.9%, Er: 0.1-0.4%, Sr: 0.05-0.6%, TiC / TiB2: 1.0-3.0%, and the balance is Al and inevitable impurities.

2. The Al-Zn series heat-treatment-free aluminum alloy according to claim 1, characterized in that: The Al-Zn series heat-treatment-free aluminum alloy comprises the following components in percentage by mass: composition: Al: 71.35-78.3%, Zn: 12.0-16.0%, Si: 4.0-9.0%, Cu: 0.5-2.0%, Mn: 0.6-1.2%, Zr: 0.1-0.4%, V: 0.1-0.8%, Er: 0.1-0.3%, Sr: 0.05-0.4%, TiC / TiB2: 1.0-2.0%, unavoidable impurities <0.04%.

3. The Al-Zn series heat-treatment-free aluminum alloy according to claim 2, characterized in that: The unavoidable impurities include Fe, C, O and Ca; And / or, the mass percentage content of a single impurity is less than 0.01%.

4. The Al-Zn series heat-treatment-free aluminum alloy according to any one of claims 1 to 3, characterized in that: The Al-Zn series heat-treatment-free aluminum alloy comprises the following preparation raw materials: pure aluminum, pure zinc, master alloy, modifier and refiner; Preferably, the master alloy includes Al-Si, Al-Cu, Al-Mn, Al-Zr, Al-V and Al-Er alloys; Preferably, the modifier comprises an Al-Sr modifier; Preferably, the refiner comprises Al-TiC / TiB2 nanoparticles.

5. The method for preparing the Al-Zn series heat-treatment-free aluminum alloy according to claim 4, characterized in that: The following steps are involved: S1, adding pure aluminum, master alloy and pure zinc in sequence and smelting to obtain alloy liquid; S2, adding a modifier and a refiner to the alloy liquid in sequence and refining the alloy liquid to obtain a refined liquid; S3, stirring, pouring and die-casting the refined liquid to obtain the Al-Zn series heat-treatment-free aluminum alloy.

6. The preparation method according to claim 5, characterized in that: In step S1, the smelting process conditions include at least one of the following: 1) The smelting temperature after adding pure aluminum is 710-800° C., and the smelting time is 1-4 hours; 2) the smelting temperature after adding the master alloy is 730-790° C., and the smelting time is 0.5-2.5 h; 3) The smelting temperature after adding pure zinc is 630-730° C., and the smelting time is 1-2 hours.

7. The preparation method according to claim 5, characterized in that: In step S2, the refining process conditions include at least one of the following: 1) The refining temperature after adding the modifier is 630-750° C. and the refining time is 0.1-1h; 2) The refining temperature after adding the refiner is 690-760°C, and the refining time is 0.1-1h.

8. The preparation method according to claim 5, characterized in that: In step S3, the pouring process conditions include at least one of the following: 1) The pouring temperature is 660-780°C; 2) The pouring speed is 0.4-1.6 m / s.

9. The preparation method according to claim 5, characterized in that: In step S3, the die-casting process conditions include at least one of the following: 1) The die casting is vacuum die casting, and the vacuum degree is 1-50kPa; 2) The die-casting injection speed is 4-6.5 m / s; 3) The injection pressure of the die casting is 100-600MPa; 4) The die casting mold temperature is 100-300°C.

10. Application of the Al-Zn series heat-treatment-free aluminum alloy according to any one of claims 1 to 4 in the automotive and aerospace fields.

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