Al-si based heat-treatment-free aluminum alloy and preparation method therefor

Abstract

An Al-Si based heat-treatment-free aluminum alloy and a preparation method therefor. The chemical composition of the Al-Si based heat-treatment-free aluminum alloy comprises: Al, Si, Zn, Cu, and Mg. In mass fractions, the chemical composition of the Al-Si based heat-treatment-free aluminum alloy further comprises: a solid solution strengthening element≥0.05%; and Fe≤0.4%. The solid solution strengthening element comprises at least one of the following: Cr, Mn, Ni, and Ti. The heat-treatment-free aluminum alloy is based on an Al-Zn-Mg-Cu alloy system, and the solid solution strengthening element such as Cr, Mn, Ni, and Ti is added and is present at≥0.05%, so that the tensile strength of the Al-Si based heat-treatment-free aluminum alloy can be effectively increased to 280 MPa or above, the yield strength to 175 MPa or above, and the elongation to 15-20%.

Description

A heat-free Al-Si aluminum alloy and its preparation method Cross-reference of related applications

[0001] This application claims priority to Chinese patent application No. 202410667312.1, filed on May 28, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of heat-free aluminum alloy technology, and more particularly to an Al-Si-based heat-free aluminum alloy and its preparation method. Background Technology

[0003] Heat-free aluminum alloys possess good fluidity and certain mechanical properties, making them widely used in automotive die casting. Based on the different elemental contents within the system, heat-free aluminum alloys can be divided into two main categories: Al-Mg and Al-Si. Compared to Al-Mg alloys, Al-Si alloys exhibit greater flexibility and ductility, thus being widely used in the integrated die casting of heat-free aluminum alloys.

[0004] However, when integrated die casting technology is applied to the automotive field, heat-free aluminum alloys need to have strong mechanical properties and ductility. In order to further enhance the mechanical properties of Al-Si heat-free aluminum alloys, a large amount of rare earth metal elements must be added. However, rare earth metal elements are expensive, resulting in high costs. Therefore, a solution to replace rare earth metal elements is needed to enhance the mechanical properties of Al-Si heat-free aluminum alloys.

[0005] The current Al-Si series heat-free aluminum alloys include: (1) heat-free die-cast aluminum alloys, whose chemical composition by mass fraction is: Si: 6.0%~8.0%, Mg: 0.3%~1.2%, Cu: 0.4%~0.58%, Fe: 0.1%~0.3%, Mn: 0.6%~0.75%, Ti: 0.05%~0.20%, Sr: 0.03%~0.07%, Ce: 0.03%~0.07%, La: 0.01%~0.04%, Zr: 0.01%~0.1%, impurity elements ≤0.01%, and the remainder is Al. The ultimate tensile strength of this aluminum alloy is 300MPa~350MPa, the yield strength is 150MPa~180MPa, and the elongation at break is 11.0%~16.0%. (2) An Al-Si-Mg-Fe aluminum alloy based on recycled aluminum with non-heat-treated high iron content, comprising the following components by mass fraction: Fe: 0.2%–0.8%, Si: 7.0%–10.0%, Mg: 0.15%–0.45%, Mn: 0.2%–0.8%, Cr: 0.1%–0.3%, Cu: 0.15%–0.7%, Zr: 0.1%–0.3%, La: 0.05%–0.12%, Ce: 0.06%–0.12%, Ti: 0.08%–0.2%, Sr: 0.008%–0.02%, with the balance being Al. This aluminum alloy has a yield strength ≥170 MPa, tensile strength ≥280 MPa, and elongation ≥8% at room temperature. Summary of the Invention

[0006] This application provides an Al-Si-based heat-treatable aluminum alloy and its preparation method to solve the following technical problem: how to improve the mechanical properties of Al-Si-based heat-treatable aluminum alloys.

[0007] In a first aspect, this application provides an Al-Si-based heat-free aluminum alloy, the chemical composition of which includes Al, Si, Zn, Cu and Mg; and by mass fraction, the chemical composition of which also includes: solid solution strengthening elements ≥0.05% and Fe ≤0.4%.

[0008] The solid solution strengthening element includes at least one of the following:

[0009] Cr, Mn, Ni and Ti.

[0010] Optionally, when the solid solution reinforcing elements are Cr, Mn, Ni, and Ti Zn, the content of the solid solution reinforcing elements, by mass fraction, satisfies: Cr ≥ 0.6%, Mn ≥ 0.4%, Ni ≥ 0.3%, and Ti ≥ 0.05%.

[0011] Optionally, the content of the solid solution reinforcing elements, by mass fraction, also satisfies the following: Cr: 0.2%–0.4%, Mn: 0.4%–0.8%, Ni: 0.3%–0.5%, and Ti: 0.05%–0.2%.

[0012] Optionally, the Fe content, by mass fraction, satisfies: Fe: 0.2% to 0.4%.

[0013] Optionally, the metallographic structure of the Al-Si-based heat-free aluminum alloy contains a Mg2Si phase, wherein the interlamellar spacing of the Mg2Si phase is ≤2μm.

[0014] Optionally, the area S1 of the Mg2Si phase and the total area S2 of the metallographic structure satisfy the following relationship:

[0015] S1 / S2≥15%.

[0016] Optionally, the metallographic structure of the Al-Si-based heat-free aluminum alloy further contains an α-Al phase, wherein the average grain size of the α-Al phase is ≤20μm.

[0017] Optionally, the Al-Si-based heat-free aluminum alloy has a tensile strength ≥280MPa, a yield strength ≥175MPa, and an elongation of 15% to 20%.

[0018] Optionally, the chemical composition of the Al-Si-based heat-free aluminum alloy, by mass fraction, also satisfies the following: Si: 7%–10%, Zn: 0.1%–0.3%, Cu: 0.6%–1.2%, Mg: 0.4%–0.8%.

[0019] Secondly, this application provides a method for preparing the Al-Si-based heat-treatable aluminum alloy described in the first aspect, the method comprising:

[0020] Al source, Si source, Zn source, Cu source, Mg source, Fe source and raw materials containing solid solution strengthening elements are preheated respectively;

[0021] The preheated Al source is smelted to obtain a molten liquid;

[0022] Preheated Si source, Fe source, Cu source, and raw materials containing the solid solution strengthening element are added to the molten liquid to obtain an intermediate melt;

[0023] The intermediate melt is cooled, and then a Mg source and a Zn source are added to the intermediate melt for mixing to obtain a mixed melt.

[0024] Using the aforementioned mixed melt as raw material, an Al-Si-based heat-free aluminum alloy was prepared.

[0025] Optionally, the final temperature of the preheating is 200℃~250℃.

[0026] Optionally, the melting temperature is 760℃~780℃, and the melting time is 10min~15min.

[0027] Optionally, the final temperature of the cooling process is 720℃~740℃.

[0028] The technical solution provided in this application has the following advantages compared with the prior art:

[0029] This application provides an Al-Si-based heat-treatable aluminum alloy, the chemical composition of which includes Al, Si, Zn, Cu and Mg; by mass fraction, the chemical composition of which also includes: solid solution strengthening element ≥0.05%, Fe ≤0.4%; the solid solution strengthening element includes at least one of the following: Cr, Mn, Ni and Ti. In the Al-Zn-Mg-Cu system of heat-free aluminum alloys, the solid solution strengthening element can be ≥0.05%, and the solid solution strengthening element can include at least one of the following: Cr, Mn, Ni, and Ti. This can promote the presence of sufficient solid solution strengthening elements in the Al-Si system of heat-free aluminum alloys. Sufficient solid solution strengthening elements can form stable solid solutions with Al and Si respectively. These stable solid solutions can improve the lattice compactness and crystal structure distribution of the Al-Si system of heat-free aluminum alloys, thereby reducing the grain boundary porosity and improving the mechanical properties of the Al-Si system of heat-free silicon alloys. In addition, Fe≤0.4% can reduce the content of iron phase in the Al-Si system of heat-free silicon alloys. A small amount of iron phase can reduce the cutting effect of iron phase on the Al-Si system of heat-free aluminum alloy matrix, so as to achieve a balance between the fluidity and mechanical properties of the Al-Si system of heat-free aluminum alloys, thereby improving the mechanical properties of the Al-Si system of heat-free aluminum alloys. Attached Figure Description

[0030] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 is a metallographic structure diagram of an Al-Si-based heat-free aluminum alloy provided in Embodiment 1 of this application;

[0033] Figure 2 is a metallographic structure diagram of an Al-Si-based heat-free aluminum alloy provided in Embodiment 2 of this application;

[0034] Figure 3 is a schematic flowchart of a method for preparing Al-Si-based heat-free aluminum alloys according to an embodiment of this application. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range such as 1, 2, 3, 4, 5, and 6, regardless of the range; in addition, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0037] In this document, terms including "comprising" and the like mean "including but not limited to". "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone; where A and B can be singular or plural. "At least one" means one or more, and "more than one" means two or more. "At least one", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of singular or plural items; for example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this application are commercially available or can be prepared using existing methods.

[0038] It should be noted that, regarding the prior art (1) in the background art, the inventors found that the heat-free die-cast aluminum alloy contains high levels of Sr, Zr, and rare earth metals such as Ce and La, which increases the cost of the heat-free die-cast aluminum alloy and is not conducive to commercial promotion; regarding the prior art (2) in the background art, the inventors found that the heat-free die-cast aluminum alloy contains high levels of Sr, Zr, and rare earth metals such as Ce and La, which increases the cost of the heat-free die-cast aluminum alloy and is not conducive to commercial promotion. In addition, the elongation of the heat-free die-cast aluminum alloy is low and cannot meet the mechanical performance requirements of integrated die-casting technology.

[0039] In addition, the inventors also discovered that the elongation of traditional Al-Si-based heat-free aluminum alloys is poor, making it difficult to meet the mechanical performance requirements of integrated die-casting technology. Therefore, how to improve the mechanical properties of Al-Si-based heat-free aluminum alloys is a technical problem that urgently needs to be solved.

[0040] Figure 1 illustrates, by way of example, the metallographic structure of an Al-Si-based heat-free aluminum alloy provided in Embodiment 1 of this application;

[0041] Figure 2 illustrates, exemplarily, the metallographic structure of an Al-Si-based heat-free aluminum alloy provided in Embodiment 2 of this application;

[0042] As shown in Figures 1 and 2, this application provides an Al-Si-based heat-free aluminum alloy. The chemical composition of the Al-Si-based heat-free aluminum alloy includes Al, Si, Zn, Cu and Mg. By mass fraction, the chemical composition of the Al-Si-based heat-free aluminum alloy also includes: solid solution strengthening elements ≥0.05% and Fe ≤0.4%.

[0043] The solid solution strengthening element includes at least one of the following:

[0044] Cr, Mn, Ni, and Ti;

[0045] In these embodiments, the solid solution strengthening element can be any one of Cr, Mn, Ni and Ti, or any two of Cr, Mn, Ni and Ti, or any three of Cr, Mn, Ni and Ti, or all four of Cr, Mn, Ni and Ti.

[0046] The solid solution strengthening element can be 0.05%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95%, 1.00%, 1.05%, or 1.10%.

[0047] The Fe content can be 0.01%, 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, or 0.40%.

[0048] It should be noted that the Al, Si, Zn, Cu and Mg included in the chemical composition of this Al-Si heat-free aluminum alloy can form an Al-Zn-Mg-Cu heat-free aluminum alloy system. In this system, Al, Si, Zn, Cu and Mg can react with each other to form a variety of solid solutions. These solid solutions can improve the lattice compactness of the Al-Si heat-free aluminum alloy and improve the crystal structure distribution of the Al-Si heat-free aluminum alloy, thereby reducing the grain boundary porosity of the Al-Si heat-free aluminum alloy and thus improving the mechanical properties of the heat-free silicon alloy.

[0049] It should be noted that the solid solution strengthening element can be a metallic element that forms a solid solution phase in Al-Si-based heat-free aluminum alloys or plays a role in refining grains in Al-Si-based heat-free aluminum alloys.

[0050] It should be noted that traditional Al-Si series heat-free aluminum alloys are a type of aluminum alloy with Si as the main additive element. They have good casting performance, fluidity, and airtightness. In addition, traditional Al-Si series heat-free aluminum alloys have the advantages of low shrinkage and low tendency to hot cracking. Therefore, after heat treatment or modification, traditional Al-Si series heat-free aluminum alloys can obtain good mechanical properties, physical properties, corrosion resistance, and machinability, making them one of the most widely used heat-free aluminum alloys. According to the Si content, Al-Si series heat-free aluminum alloys can be divided into three categories: eutectic alloys, hypereutectic alloys, and hypoeutectic alloys. The Al-Si series heat-free aluminum alloy of this application is based on the advantages of traditional Al-Si series heat-free aluminum alloys, with the addition of Mg, Cu, and Zn in Al. The formation of an Al-Zn-Mg-Cu alloy system within the Al-Si-based heat-free aluminum alloy can improve both its strength and fluidity. However, the strength of the Al-Si-based heat-free aluminum alloy containing this alloy system still cannot meet the requirements of automotive integrated die casting. This application further adds solid solution strengthening elements to the Al-Zn-Mg-Cu alloy system to form a large amount of solid solution or refine the grains of the Al-Si-based heat-free aluminum alloy, thereby effectively improving its strength to meet the requirements of automotive integrated die casting.

[0051] In some alternative embodiments, when the solid solution reinforcing elements are Cr, Mn, Ni and Ti, the content of the solid solution reinforcing elements, by mass fraction, satisfies: Cr ≥ 0.6%, Mn ≥ 0.4%, Ni ≥ 0.3% and Ti ≥ 0.05%.

[0052] In these embodiments, the content of solid solution strengthening elements can satisfy Cr ≥ 0.6%, Mn ≥ 0.4%, Ni ≥ 0.3%, and Ti ≥ 0.05%. This promotes the presence of sufficient Cr, Mn, Ni, and Ti in the Al-Si heat-free aluminum alloy. Sufficient Cr can dissolve in the aluminum lattice of the Al-Si heat-free aluminum alloy, forming a uniform Cr crystal structure. This uniform Cr crystal structure reduces grain boundary porosity in the Al-Si heat-free aluminum alloy, thereby improving the lattice tightness of the Al-Si heat-free aluminum alloy. The density of the Al-Si alloy can improve its mechanical properties. Sufficient Mn can react with Al in the Al-Si alloy to form a large amount of MnAl solid solution. On one hand, this large amount of MnAl solid solution can chemically react with Si in the Al-Si alloy to generate a large amount of AlMnSi phase. These AlMnSi phases can refine the grain size of the Al-Si alloy, thus improving its mechanical properties. On the other hand, the large amount of MnAl solid solution can dissolve the Al-Si alloy's... The formation of the iron phase into the AlFeMnSi compound phase can reduce the cutting effect of the iron phase on the matrix of Al-Si-based heat-treatable aluminum alloys. Furthermore, the formed AlFeMnSi compound phase can further refine the grains of Al-Si-based heat-treatable aluminum alloys, thereby improving their mechanical properties. Sufficient Ni can improve the morphology of the solidification structure of Al-Si-based heat-treatable aluminum alloys, refining the grains and thus increasing their strength and toughness. Sufficient Ti can react with Al-Si... In Al-Si series heat-free aluminum alloys, Al forms a Ti solid solution structure. This solid solution structure can reduce grain boundary porosity in Al-Si series heat-free aluminum alloys, thereby improving the lattice compactness and mechanical properties. In addition, sufficient Ti can also form a large number of intermediate phase solid solutions with other solid solution strengthening elements and Mg and Zn in Al-Si series heat-free aluminum alloys. These intermediate phase solid solutions have good hardness and ductility, thereby improving the strength and elongation of Al-Si series heat-free aluminum alloys.

[0053] In some alternative embodiments, the content of the solid solution reinforcing elements, by mass fraction, further satisfies the following: Cr: 0.2%–0.4%, Mn: 0.4%–0.8%, Ni: 0.3%–0.5%, and Ti: 0.05%–0.2%.

[0054] In these embodiments, the solid solution strengthening elements may include: Cr: 0.2%–0.4%, Mn: 0.4%–0.8%, Ni: 0.3%–0.5%, and Ti: 0.05%–0.2%. This can further promote the presence of sufficient solid solution strengthening elements in the Al-Si heat-free aluminum alloy. Sufficient solid solution strengthening elements can form stable solid solutions with Al and Si respectively. These stable solid solutions can further improve the lattice compactness and crystal structure distribution of the Al-Si heat-free aluminum alloy, thereby further reducing the grain boundary porosity of the Al-Si heat-free aluminum alloy, and further improving the mechanical properties of the heat-free silicon alloy.

[0055] The Cr content can be: 0.20%, 0.25%, 0.30%, 0.35%, or 0.40%.

[0056] The Mn content can be 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, or 0.80%.

[0057] The Ni content can be 0.30%, 0.35%, 0.40%, 0.45%, or 0.50%.

[0058] The Ti content can be 0.05%, 0.10%, 0.15%, or 0.20%.

[0059] In some alternative embodiments, the Fe content, by mass fraction, satisfies: Fe: 0.2% to 0.4%;

[0060] In these embodiments, the mass fraction of Fe can be 0.2% to 0.4%, which can further reduce the Fe content of Al-Si-based heat-free aluminum alloys. A small amount of Fe can react with Mn in the solid solution strengthening element and Al and Si in the Al-Si-based heat-free aluminum alloy to form an AlFeMnSi compound phase, which can reduce the cutting effect of iron on the matrix of Al-Si-based heat-free aluminum alloy. In addition, the generated AlFeMnSi compound phase can further refine the grains of Al-Si-based heat-free aluminum alloy, thereby further improving the mechanical properties of Al-Si-based heat-free aluminum alloy.

[0061] The Fe content can be 0.20%, 0.25%, 0.30%, 0.35%, or 0.40%.

[0062] In some optional embodiments, the metallographic structure of the Al-Si-based heat-free aluminum alloy includes a Mg2Si phase, wherein the interlamellar spacing of the Mg2Si phase is ≤3μm;

[0063] In these embodiments, the metallographic structure of the heat-free aluminum alloy may include a Mg2Si phase with a lamellar spacing of ≤3μm. This can promote a dense arrangement of the Mg2Si phase in the metallographic structure of the Al-Si heat-free aluminum alloy. On the one hand, the densely arranged Mg2Si phase can fill the lattice of the Al-Si heat-free aluminum alloy, thereby improving the lattice compactness of the Al-Si heat-free aluminum alloy. On the other hand, the densely arranged Mg2Si phase can improve the grain boundary porosity of the Al-Si heat-free aluminum alloy, thereby effectively improving the mechanical properties of the heat-free aluminum alloy.

[0064] It should be noted that the Mg2Si phase is a solid solution phase formed by Mg and Si in Al-Si system heat-free aluminum alloys.

[0065] In some optional embodiments, the area S1 of the Mg2Si phase and the total area S2 of the metallographic structure satisfy the following relationship:

[0066] S1 / S2 ≥ 10%;

[0067] In these embodiments, the area S1 of the Mg2Si phase and the total area S2 of the metallographic structure can satisfy... This can promote the presence of sufficient Mg2Si phase in the microstructure of Al-Si system heat-free aluminum alloys. Sufficient Mg2Si phase can effectively improve the mechanical properties of Al-Si system heat-free aluminum alloys.

[0068] In some optional embodiments, the metallographic structure of the Al-Si-based heat-free aluminum alloy further includes an α-Al phase, wherein the average grain size of the α-Al phase is ≤20μm;

[0069] In these embodiments, the microstructure of the Al-Si-based heat-free aluminum alloy may also include an α-Al phase, and the average grain size of the α-Al phase is ≤20μm, which can promote the presence of a sufficiently fine α-Al phase in the Al-Si-based heat-free aluminum alloy. The sufficiently fine α-Al phase can effectively improve the mechanical properties of the Al-Si-based heat-free aluminum alloy.

[0070] It should be noted that the average grain size refers to the estimated value of the two-dimensional size distribution of multiple irregularly shaped α-Al phases on the metallographic structure detection surface. This estimated value is a value converted from the Scherrer formula and can represent the actual size of the α-Al phase to a certain extent.

[0071] It should be noted that the α-Al phase is the phase transformation structure of Al in Al-Si-based heat-free aluminum alloys during the smelting process. The α-Al phase has strong hardness and fine grain size, which can refine the grains of Al-Si-based heat-free aluminum alloys, thereby improving the uniformity of grain distribution and thus improving the mechanical properties of Al-Si-based heat-free aluminum alloys.

[0072] In some optional embodiments, the Al-Si-based heat-free aluminum alloy has a tensile strength ≥280MPa, a yield strength ≥175MPa, and an elongation of 15% to 20%.

[0073] In these embodiments, the tensile strength of the Al-Si-based heat-free aluminum alloy can be ≥280MPa, the yield strength of the Al-Si-based heat-free aluminum alloy can be ≥175MPa, and the elongation of the Al-Si-based heat-free aluminum alloy can be 15% to 20%. This indicates that the Al-Si-based heat-free aluminum alloy has good tensile strength, good yield performance, and good elongation. Therefore, it can be shown that the solid solution strengthening elements provided in this application can effectively improve the mechanical properties of the Al-Si-based heat-free aluminum alloy.

[0074] In some alternative embodiments, the chemical composition of the Al-Si-based heat-free aluminum alloy, by mass fraction, also satisfies the following: Si: 7%–10%, Zn: 0.1%–0.3%, Cu: 0.6%–1.2%, Mg: 0.4%–0.8%.

[0075] In these embodiments, the chemical composition of the Al-Si-based heat-free aluminum alloy can also meet the following requirements: Si: 7%–10%, Zn: 0.1%–0.3%, Cu: 0.6%–1.2%, Mg: 0.4%–0.8%. This ensures that the Al-Si-based heat-free aluminum alloy contains sufficient amounts of Si, Zn, Cu, and Mg. The sufficient amount of Si can form fine, well-stable aluminum-silicon solid solutions with Al, and these aluminum-silicon solid solutions can be distributed throughout the Al-Si-based heat-free aluminum alloy. In treating the crystal lattice of aluminum alloys, improving lattice compactness and thermal stability can enhance the high-temperature moldability of Al-Si heat-treatable aluminum alloys, reducing their tendency for hot cracking and thus increasing their shrinkage rate. Sufficient Zn can form numerous Zn₂Mg strengthening phases with Mg, which can be distributed in the grain boundary voids of Al-Si heat-treatable aluminum alloys, thereby improving their mechanical properties. Sufficient Zn increases the fluidity of solid solutions at the grain boundaries of Al-Si alloys requiring no heat treatment, thereby improving their ductility and elongation. Sufficient Cu can directly distribute within the grain boundary voids of Al-Si alloys, increasing their grain boundary strength and thus their mechanical properties. Furthermore, sufficient Cu can combine with various solid solutions to enhance their strength, further improving overall performance. Mechanical properties of high-Al-Si heat-treatable aluminum alloys: Sufficient Mg can form magnesium-aluminum solid solutions with Al in Al-Si heat-treatable aluminum alloys. These magnesium-aluminum solid solutions can be distributed between the crystal lattice of Al-Si heat-treatable aluminum alloys, reducing interlamellar gaps and thus improving the lattice compactness of Al-Si heat-treatable aluminum alloys, thereby improving their mechanical properties. In addition, sufficient Mg can also form high-strength... Intermetallic compounds, these Intermetallic compounds can fill the grain boundary surfaces and lattices of Al-Si-based heat-treatable aluminum alloys, improving the grain boundary surface distribution and lattice compactness, thereby enhancing the mechanical properties of Al-Si-based heat-treatable aluminum alloys.

[0076] The Si content can be 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, or 10.0%.

[0077] The Zn content can be 0.10%, 0.15%, 0.20%, 0.25%, or 0.30%.

[0078] The Cu content can be 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, or 1.2%.

[0079] The Mg content can be 0.4%, 0.5%, 0.6%, 0.7%, or 0.8%.

[0080] Based on a general inventive concept, as shown in Figure 3, this application provides a method for preparing the Al-Si system heat-free aluminum alloy, the method comprising:

[0081] S1. Preheat the Al source, Si source, Zn source, Cu source, Mg source, Fe source and raw materials containing solid solution strengthening elements respectively;

[0082] S2. The preheated Al source is smelted to obtain a molten liquid;

[0083] S3. Add the preheated Si source, Fe source, Cu source, and raw materials containing the solid solution strengthening element to the molten liquid to obtain an intermediate melt;

[0084] S4. The intermediate melt is cooled down, and then Mg source and Zn source are added to the intermediate melt for mixing to obtain a mixed melt.

[0085] S5. Using the aforementioned mixed melt as raw material, an Al-Si-based heat-free aluminum alloy is prepared.

[0086] This method is for the preparation of the above-mentioned Al-Si system heat-free aluminum alloy. The specific composition of the Al-Si system heat-free aluminum alloy can be referred to the above embodiments. Since this method adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0087] It should be noted that the raw material containing the solid solution strengthening element can be selectively added from Cr source, Mn source, Ni source and Ti source. Any one of Cr source, Mn source, Ni source and Ti source can be added, any two of Cr source, Mn source, Ni source and Ti source can be added, any three of Cr source, Mn source, Ni source and Ti source can be added, or all of Cr source, Mn source, Ni source and Ti source can be added.

[0088] It should be noted that the Al source can be aluminum ingots with a purity > 99%; the Si source can be an additive containing Si, such as (Al-Si alloy); the Fe source can be an additive containing Fe (such as Al-Fe alloy); the Cu source can be an Al-Cu master alloy or elemental Cu; the Cr source can be an Al-Cr master alloy or elemental Cr; the Mg source can be an Al-Mg master alloy or elemental Mg; the Mn source can be an Al-Mn master alloy or elemental Mn; the Ni source can be an Al-Ni master alloy or elemental Ni; the Ti source can be an Al-Ti master alloy or elemental Ti; and the Zn source can be an Al-Zn master alloy or elemental Zn.

[0089] It should be noted that Al-Si series heat-free aluminum alloys can be prepared by using mixed melt as raw material and processing the melt through stirring, refining, impurity removal and casting. Among them, stirring is mainly to promote the full mixing of various raw material components; refining is mainly to remove harmful elements from the mixed melt and form solid impurity slag; and impurity removal is mainly to remove the impurity slag generated in the refining stage and the bubbles generated in the stirring stage, so as to further improve the uniformity of the mixed melt.

[0090] It should be noted that the impurity removal can be carried out through two cooling processes. The first cooling to 690℃~710℃ can promote the rapid aggregation of impurity components in the mixed melt on the surface. The second cooling to 675℃~685℃ can promote the rapid discharge of impurity gases from the mixed melt, thereby finally obtaining an Al-Si-based heat-treatable aluminum alloy with uniform alloy composition. The endpoint temperature of the first cooling can be 690℃, 695℃, 700℃, 705℃ or 710℃. The endpoint temperature of the second cooling can be 675℃, 676℃, 677℃, 678℃, 679℃, 680℃, 681℃, 682℃, 683℃, 684℃ or 685℃.

[0091] It should be noted that the mixing can be carried out by stirring for 5 to 10 minutes, which can promote the thorough mixing between the intermediate melt, the Mg source, and the Zn source, thereby obtaining a mixed melt with uniformly distributed alloy components; the stirring time can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes.

[0092] It should be noted that the refining time can be 15 min to 25 min. The refining method can be used to remove solid impurities and gaseous impurities from the mixed melt, thereby obtaining a pure mixed melt with uniformly distributed alloy components. The refining time can be 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min or 25 min.

[0093] It should be noted that the refining process can use a refining furnace as the refining vessel, preheated inert gas as the refining carrier, or a refining agent as the refining reagent, to promote thorough refining and thus obtain a pure mixed melt with uniformly distributed alloy components.

[0094] In some optional embodiments, the final temperature of the preheating is 200°C to 250°C;

[0095] In these embodiments, the final temperature of preheating can be 200°C to 250°C. This can be used to preheat raw materials containing Al, Si, Fe, Cu, Mg, Zn sources and solid solution strengthening elements, so as to enable each raw material to have a certain amount of heat, which can facilitate the rapid melting process in the subsequent preparation stage, thereby obtaining a mixed melt with uniform alloy composition.

[0096] The final temperature of preheating can be 200℃, 210℃, 220℃, 230℃, 240℃ or 250℃.

[0097] In some optional embodiments, the melting temperature is 760°C to 780°C, and the melting time is 10 min to 15 min;

[0098] In these embodiments, the melting temperature can be 760°C to 780°C, and the melting time can be 10 min to 15 min, which can promote the full melting of the Al source. In addition, it can facilitate the full melting of subsequent Si source, Fe source, Cu source and raw materials containing solid solution strengthening elements, thereby obtaining an intermediate melt with uniform alloy composition.

[0099] The melting temperature can be 760℃, 765℃, 770℃, 775℃ or 780℃.

[0100] The melting time can be 10 min, 11 min, 12 min, 13 min, 14 min or 15 min.

[0101] In some optional embodiments, the endpoint temperature of the cooling is 720°C to 740°C;

[0102] In these embodiments, the final temperature of cooling can be 720°C to 740°C. On the one hand, this can promote the full melting of Mg and Zn sources, thereby reducing the energy consumption of the overall preparation stage. On the other hand, it can reduce the melting temperature, thereby reducing the possibility of bubbles appearing during the addition of Mg and Zn sources, which can improve the uniformity of the distribution of various alloy components in the intermediate melt.

[0103] The endpoint temperature for this cooling process can be 720℃, 725℃, 730℃, 735℃, or 740℃.

[0104] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards; if no corresponding industry standard exists, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.

[0105] Example 1

[0106] As shown in Figure 1, the chemical composition of an Al-Si heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as the solution strengthening elements, satisfies the following by mass fraction:

[0107] Si: 7%, Cu: 0.6%, Cr: 0.3%, Mg: 0.7%, Mn: 0.6%, Ni: 0.35%, Ti: 0.05%, Zn: 0.15%, Fe: 0.4%, with the remainder being Al and unavoidable impurity elements.

[0108] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0109] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0110] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0111] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0112] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0113] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0114] The final temperature of the preheating is 220℃.

[0115] The melting temperature was 770℃, and the melting time was 10 minutes.

[0116] The final temperature of the cooling process was 730℃.

[0117] Example 2

[0118] As shown in Figure 2, the chemical composition of an Al-Si heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as the solution strengthening elements, satisfies the following by mass fraction:

[0119] Si: 10%, Cu: 1.2%, Cr: 0.4%, Mg: 0.8%, Mn: 0.8%, Ni: 0.5%, Ti: 0.2%, Zn: 0.3%, Fe: 0.4%, with the remainder being Al and unavoidable impurity elements.

[0120] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0121] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0122] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0123] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0124] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0125] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0126] The final temperature of the preheating is 220℃.

[0127] The melting temperature was 770℃, and the melting time was 10 minutes.

[0128] The final temperature of the cooling process was 730℃.

[0129] Example 3

[0130] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0131] The composition is as follows: Si: 9%, Cu: 1.2%, Cr: 0.4%, Mg: 0.4%, Mn: 0.6%, Ni: 0.35%, Ti: 0.15%, Zn: 0.2%, Fe: 0.3%, with the remainder being Al and unavoidable impurity elements.

[0132] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0133] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0134] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0135] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0136] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0137] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0138] The final temperature of the preheating is 220℃.

[0139] The melting temperature was 770℃, and the melting time was 10 minutes.

[0140] The final temperature of the cooling process was 730℃.

[0141] Example 4

[0142] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0143] Si: 9%, Cu: 0.7%, Cr: 0.2%, Mg: 0.7%, Mn: 0.4%, Ni: 0.5%, Ti: 0.2%, Zn: 0.15%, Fe: 0.2%, with the remainder being Al and unavoidable impurity elements.

[0144] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0145] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0146] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0147] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0148] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0149] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0150] The final temperature of the preheating is 220℃.

[0151] The melting temperature was 770℃, and the melting time was 10 minutes.

[0152] The final temperature of the cooling process was 730℃.

[0153] Example 5

[0154] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0155] Si: 7%, Cu: 1.2%, Cr: 0.3%, Mg: 0.5%, Mn: 0.4%, Ni: 0.3%, Ti: 0.2%, Zn: 0.15%, Fe: 0.2%, with the remainder being Al and unavoidable impurity elements.

[0156] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0157] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0158] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0159] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0160] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0161] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0162] The final temperature of the preheating is 240℃.

[0163] The melting temperature was 780℃, and the melting time was 12 minutes.

[0164] The final temperature of the cooling process was 740℃.

[0165] Example 6

[0166] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0167] Si: 7%, Cu: 0.6%, Cr: 0.3%, Mg: 0.5%, Mn: 0.5%, Ni: 0.5%, Ti: 0.15%, Zn: 0.2%, Fe: 0.2%, with the remainder being Al and unavoidable impurity elements.

[0168] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0169] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0170] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0171] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0172] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0173] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0174] The final temperature of the preheating is 240℃.

[0175] The melting temperature was 780℃, and the melting time was 12 minutes.

[0176] The final temperature of the cooling process was 740℃.

[0177] Example 7

[0178] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0179] Si: 7.5%, Cu: 0.7%, Cr: 0.3%, Mg: 0.8%, Mn: 0.8%, Ni: 0.4%, Ti: 0.05%, Zn: 0.2%, Fe: 0.25%, with the remainder being Al and unavoidable impurity elements.

[0180] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0181] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0182] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0183] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0184] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0185] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0186] The final temperature of the preheating is 200℃.

[0187] The melting temperature was 760℃ and the melting time was 15 minutes.

[0188] The final temperature of the cooling process was 720℃.

[0189] Example 8

[0190] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0191] Si: 10%, Cu: 0.6%, Cr: 0.4%, Mg: 0.4%, Mn: 0.4%, Ni: 0.4%, Ti: 0.10%, Zn: 0.2%, Fe: 0.25%, with the remainder being Al and unavoidable impurity elements.

[0192] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0193] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0194] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0195] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0196] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0197] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0198] The final temperature of the preheating is 200℃.

[0199] The melting temperature was 760℃ and the melting time was 15 minutes.

[0200] The final temperature of the cooling process was 720℃.

[0201] Comparative Example 1

[0202] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0203] Si: 5%, Cu: 0.6%, Cr: 0.3%, Mg: 0.5%, Mn: 0.6%, Ni: 0.35%, Ti: 0.05%, Zn: 0.15%, Fe: 0.2%, with the remainder being Al and unavoidable impurity elements.

[0204] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0205] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0206] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0207] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0208] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0209] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0210] The final temperature of the preheating is 220℃.

[0211] The melting temperature was 770℃, and the melting time was 10 minutes.

[0212] The final temperature of the cooling process was 730℃.

[0213] Comparative Example 2

[0214] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0215] Si: 13%, Cu: 0.6%, Cr: 0.3%, Mg: 0.7%, Mn: 0.6%, Ni: 0.35%, Ti: 0.05%, Zn: 0.15%, Fe: 0.4%, with the remainder being Al and unavoidable impurity elements.

[0216] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0217] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0218] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0219] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0220] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0221] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0222] The final temperature of the preheating is 220℃.

[0223] The melting temperature was 770℃, and the melting time was 10 minutes.

[0224] The final temperature of the cooling process was 730℃.

[0225] Comparative Example 3

[0226] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0227] Si: 7%, Cu: 0.6%, Mg: 0.5%, Zn: 0.15%, Fe: 0.2%, with the remainder being Al and unavoidable impurity elements.

[0228] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0229] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0230] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0231] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0232] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0233] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0234] The final temperature of the preheating is 220℃.

[0235] The melting temperature was 770℃, and the melting time was 10 minutes.

[0236] The final temperature of the cooling process was 730℃.

[0237] Comparative Example 4

[0238] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0239] Si: 7%, Cu: 0.6%, Cr: 1.0%, Mg: 0.7%, Mn: 0.7%, Ni: 1.0%, Ti: 0.8%, Zn: 0.15%, Fe: 0.2%, with the remainder being Al and unavoidable impurity elements.

[0240] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0241] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0242] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0243] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0244] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0245] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0246] The final temperature of the preheating is 220℃.

[0247] The melting temperature was 770℃, and the melting time was 10 minutes.

[0248] The final temperature of the cooling process was 730℃.

[0249] Comparative Example 5

[0250] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0251] Si: 7%, Cu: 0.6%, Cr: 0.3%, Mg: 0.7%, Mn: 0.6%, Ni: 0.35%, Ti: 0.05%, Zn: 0.15%, Fe: 0.4%, with the remainder being Al and unavoidable impurity elements.

[0252] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0253] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0254] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0255] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0256] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0257] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0258] The final temperature of the preheating is 150℃.

[0259] The melting temperature was 770℃, and the melting time was 10 minutes.

[0260] The final temperature of the cooling process was 730℃.

[0261] Comparative Example 6

[0262] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0263] Si: 7%, Cu: 0.6%, Cr: 0.3%, Mg: 0.7%, Mn: 0.6%, Ni: 0.35%, Ti: 0.05%, Zn: 0.15%, Fe: 0.4%, with the remainder being Al and unavoidable impurity elements.

[0264] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0265] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0266] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0267] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0268] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0269] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0270] The final temperature of the preheating is 300℃.

[0271] The melting temperature was 770℃, and the melting time was 10 minutes.

[0272] The final temperature of the cooling process was 730℃.

[0273] Comparative Example 7

[0274] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0275] Si: 7%, Cu: 0.6%, Cr: 0.3%, Mg: 0.7%, Mn: 0.6%, Ni: 0.35%, Ti: 0.05%, Zn: 0.15%, Fe: 0.4%, with the remainder being Al and unavoidable impurity elements.

[0276] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0277] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0278] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0279] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0280] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0281] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0282] The final temperature of the preheating is 220℃.

[0283] The melting temperature is 750℃ and the melting time is 5 minutes.

[0284] The final temperature of the cooling process is 700℃.

[0285] Comparative Example 8

[0286] An Al-Si-based heat-treatable aluminum alloy, with Cr, Mn, Ni, and Ti as solution strengthening elements, has the following chemical composition by mass fraction:

[0287] Si: 7%, Cu: 0.6%, Cr: 0.3%, Mg: 0.7%, Mn: 0.6%, Ni: 0.35%, Ti: 0.05%, Zn: 0.15%, Fe: 0.4%, with the remainder being Al and unavoidable impurity elements.

[0288] As shown in Figure 3, a method for preparing Al-Si based aluminum alloys without heat treatment includes:

[0289] S1. The Al source, Si source, Fe source, Cu source, Cr source, Mg source, Mn source, Ni source, Ti source and Zn source are preheated respectively to obtain preheated raw materials;

[0290] S2. Melt the Al source of the preheated raw material to obtain a molten liquid;

[0291] S3. Add preheated Si, Fe, Cu, Cr, Mn, Ni and Ti sources to the molten liquid and mix to obtain an intermediate melt;

[0292] S4. Cool the intermediate melt, then add Mg source and Zn source to the intermediate melt for mixing to obtain a mixed melt;

[0293] S5. Using mixed melt as raw material, Al-Si series heat-free aluminum alloys are prepared.

[0294] The melting temperature is 800℃ and the melting time is 20 minutes.

[0295] The final temperature of the cooling process was 780℃.

[0296] Relevant experimental and effect data:

[0297] Metallographic analysis was performed on the Al-Si-based heat-free aluminum alloys obtained in Example 1 and Example 2, and the results are shown in Figure 1 and Figure 2, respectively.

[0298] The mechanical properties of the Al-Si heat-free aluminum alloys obtained in each embodiment and comparative example were then tested, and the results are shown in Table 1.

[0299] Table 1. Mechanical property results of Al-Si heat-treatable aluminum alloys obtained in each embodiment and comparative example.

[0300]

[0301] As shown in Table 1, the Al-Si heat-treatable aluminum alloy provided in this application embodiment, based on the Al-Zn-Mg-Cu alloy system, with the addition of solid solution strengthening elements such as Cr, Mn, Ni, and Ti, and a solid solution strengthening element content of ≥0.05%, can promote the Al-Si heat-treatable aluminum alloy to contain sufficient solid solution strengthening elements. Sufficient solid solution strengthening elements can form stable solid solutions with Al and Si respectively. These stable solid solutions can improve the lattice compactness of the Al-Si heat-treatable aluminum alloy and enhance its overall performance. The degree of crystal structure distribution can reduce the grain boundary porosity of Al-Si heat-free aluminum alloys; in addition, Fe≤0.4% can reduce the content of iron phase in Al-Si heat-free aluminum alloys. A small amount of iron phase can reduce the cutting effect of iron phase on the Al-Si heat-free aluminum alloy matrix, so as to achieve a balance between the fluidity and mechanical properties of Al-Si heat-free aluminum alloys. This can effectively improve the tensile strength of Al-Si heat-free aluminum alloys to 280MPa and above, the yield strength to 175MPa and above, and the elongation to 15%~20%.

[0302] In addition, the Al-Si-based heat-free aluminum alloy provided in this application embodiment does not contain rare earth metal elements in its chemical composition, and it also has good elongation, which can reduce the cost of the Al-Si-based heat-free aluminum alloy and thus improve its economic efficiency.

[0303] Furthermore, this application provides an Al-Si-based heat-free aluminum alloy with good mechanical properties. This Al-Si-based heat-free aluminum alloy can be applied to integrated die-casting technology in automobiles, such as integrated die-casting of automobile front compartments and integrated die-casting of automobile rear floor parts.

[0304] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. An Al-Si based aluminum alloy that requires no heat treatment, wherein the chemical composition of the Al-Si based aluminum alloy requires no heat treatment comprises: Al, Si, Zn, Cu, and Mg; The chemical composition of the Al-Si-based heat-free aluminum alloy, by mass fraction, also includes: solid solution strengthening elements ≥0.05%, Fe ≤0.4%; The solid solution strengthening element includes at least one of the following: Cr, Mn, Ni and Ti.

2. The Al-Si based heat-treatable aluminum alloy according to claim 1, wherein, When the solid solution reinforcing elements are Cr, Mn, Ni and Ti, the content of the solid solution reinforcing elements, by mass fraction, satisfies: Cr ≥ 0.6%, Mn ≥ 0.4%, Ni ≥ 0.3% and Ti ≥ 0.05%.

3. The Al-Si based heat-treatable aluminum alloy according to claim 1 or 2, wherein, The content of the solid solution reinforcing elements, by mass fraction, also satisfies the following: Cr: 0.2%–0.4%, Mn: 0.4%–0.8%, Ni: 0.3%–0.5%, and Ti: 0.05%–0.2%.

4. The Al-Si based heat-treatable aluminum alloy according to claim 1, wherein, The Fe content, by mass fraction, meets the following requirement: Fe: 0.2%–0.4%.

5. The Al-Si based heat-treatable aluminum alloy according to claim 1, wherein, The metallographic structure of the Al-Si-based heat-free aluminum alloy contains a Mg2Si phase, and the interlamellar spacing of the Mg2Si phase is ≤2μm.

6. The Al-Si based heat-treatable aluminum alloy according to claim 5, wherein, The area S1 of the Mg2Si phase and the total area S2 of the metallographic structure satisfy the following relationship: S1 / S2≥15%.

7. The Al-Si based heat-treatable aluminum alloy according to claim 1, 5, or 6, wherein, The metallographic structure of the Al-Si-based heat-free aluminum alloy also contains an α-Al phase, the average grain size of which is ≤20μm.

8. The Al-Si based heat-treatable aluminum alloy according to claim 1, wherein, The Al-Si-based heat-free aluminum alloy has a tensile strength ≥280MPa, a yield strength ≥175MPa, and an elongation of 15% to 20%.

9. The Al-Si based heat-treatable aluminum alloy according to claim 1, wherein, The chemical composition of the Al-Si series heat-free aluminum alloy, by mass fraction, also meets the following requirements: Si: 7%–10%, Zn: 0.1%–0.3%, Cu: 0.6%–1.2%, Mg: 0.4%–0.8%.

10. A method for preparing the Al-Si-based heat-treatable aluminum alloy according to any one of claims 1 to 9, wherein, The method includes: Al source, Si source, Zn source, Cu source, Mg source, Fe source and raw materials containing solid solution strengthening elements are preheated respectively; The preheated Al source is smelted to obtain a molten liquid; Preheated Si source, Fe source, Cu source, and raw materials containing the solid solution strengthening element are added to the molten liquid to obtain an intermediate melt; The intermediate melt is cooled, and then Mg source and Zn source are added to the intermediate melt for mixing to obtain a mixed melt. Using the aforementioned mixed melt as raw material, an Al-Si-based heat-free aluminum alloy was prepared.

11. The method according to claim 10, wherein, The final temperature of the preheating is 200℃~250℃.

12. The method according to claim 10, wherein, The melting temperature is 760℃~780℃, and the melting time is 10min~15min.

13. The method according to claim 10, wherein, The final temperature of the cooling process is 720℃~740℃.

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