High-strength Al-Mg series aluminum alloy, preparation method thereof and aluminum alloy structural part

Abstract

The invention provides a high-strength Al-Mg series aluminum alloy, a preparation method thereof and an aluminum alloy structural part. The high-strength Al-Mg series aluminum alloy is prepared from the following components in percentage by mass: 6.5 to 10 weight percent of Mg, 0.01 to 0.5 weight percent of Zn, 0.01 to 0.2 weight percent of Si, 0.01 to 0.5 weight percent of Fe, 0 to 0.5 weight percent of Cu, 0 to 0.8 weight percent of Mn, 0 to 0.2 weight percent of Ti, 0 to 0.5 weight percent of Zr, 0 to 0.2 weight percent of V, 0 to 0.1 weight percent of B, 0 to 0.1 weight percent of Be and 0 to 0.5 weight percent of Ag.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, and more particularly to a high-strength Al-Mg aluminum alloy, a method for preparing the high-strength Al-Mg aluminum alloy, and aluminum alloy structural components. Background Technology

[0002] High-strength Al-Mg aluminum alloys are widely used in shipbuilding, marine engineering, transportation, and pressure vessels due to their low specific gravity, high strength, good machinability, and excellent corrosion resistance. Mg has a high solid solubility in the aluminum matrix, which can significantly improve the strength and ductility of aluminum alloys. However, with increasing Mg content, intermetallic compounds Al3Mg2 (β phase) easily precipitate at grain boundaries. This phase exhibits significant brittleness, and its continuous or semi-continuous grain boundary precipitation enhances the alloy's susceptibility to intergranular corrosion, significantly reducing the strength and elongation of the aluminum alloy. Summary of the Invention

[0003] In view of the above-mentioned deficiencies of the prior art, the present invention provides a high-strength Al-Mg aluminum alloy, which aims to improve the strength and elongation of Al-Mg aluminum alloy.

[0004] This invention provides a high-strength Al-Mg aluminum alloy containing 6.5-10% Mg, 0.01-0.5% Zn, 0.01-0.2% Si, 0.01-0.5% Fe, 0-0.5% Cu, 0-0.8% Mn, 0-0.2% Ti, 0-0.5% Zr, 0-0.2% V, 0-0.1% B, 0-0.1% Be, 0-0.5% Ag, and Al, as well as unavoidable impurities.

[0005] Furthermore, the high-strength Al-Mg aluminum alloy contains 7-9% Mg, 0.05-0.5% Zn, 0.02-0.2% Si, 0.1-0.4% Fe, 0.001-0.5% Cu, 0.001-0.8% Mn, 0.001-0.2% Ti, 0.001-0.5% Zr, 0.001-0.2% V, 0.001-0.1% B, 0.001-0.1% Be, and 0.001-0.5% Ag by mass.

[0006] Furthermore, at least one of the following conditions must be met: The sum of the mass percentages of Mg and Zn is 7.5-10.5%; The mass ratio of Mn to Fe is greater than 0.4; The sum of the mass percentages of Si and Fe is less than 0.6%; The sum of the mass percentage contents of V and Ti is less than 0.4%.

[0007] Furthermore, the high-strength Al-Mg aluminum alloy also contains at least one of In, Nb, Bi, Ge, Mo, Ni, Te, Co, Cr, Sr, Sn, RE, Cd, and Ca, wherein the mass percentage content of In is 0-0.2%, the mass percentage content of Nb is 0-0.5%, the mass percentage content of Bi is 0-0.2%, the mass percentage content of Ge is 0-0.5%, the mass percentage content of Mo is 0-0.5%, the mass percentage content of Ni is 0-0.5%, the mass percentage content of Te is 0-0.5%, the mass percentage content of Co is 0-0.5%, the mass percentage content of Cr is 0-0.3%, the mass percentage content of Sr is 0-0.2%, the mass percentage content of Sn is 0-0.2%, the mass percentage content of RE is 0-0.5%, the mass percentage content of Cd is 0-0.3%, and the mass percentage content of Ca is 0-0.05%.

[0008] This invention also provides a method for preparing a high-strength Al-Mg aluminum alloy, comprising the following steps: The Al source is subjected to a first heating treatment to obtain molten aluminum. Add Mg source, Zn source, Si source, Fe source, Cu source, Mn source, Ti source, Zr source, V source, B source, Ag source and Be source to the aluminum liquid, and perform a second heating treatment to obtain alloy liquid; The alloy liquid is refined, slag removed, and formed to obtain a high-strength Al-Mg aluminum alloy. The high-strength Al-Mg aluminum alloy contains 6.5-10% Mg, 0.01-0.5% Zn, 0.01-0.2% Si, 0.01-0.5% Fe, 0-0.5% Cu, 0-0.8% Mn, 0-0.2% Ti, 0-0.5% Zr, 0-0.2% V, 0-0.1% B, 0-0.1% Be, 0-0.5% Ag, and Al, as well as unavoidable impurities.

[0009] Furthermore, the preparation method of the high-strength Al-Mg aluminum alloy further includes the step of adding at least one of the following sources to the molten aluminum: In, Nb, Bi, Ge, Mo, Ni, Te, Co, Cr, Sr, Sn, RE, Cd, and Ca. The mass percentage content of In is 0-0.2%, Nb is 0-0.5%, Bi is 0-0.2%, Ge is 0-0.5%, Mo is 0-0.5%, Ni is 0-0.5%, Te is 0-0.5%, Co is 0-0.5%, Sr is 0-0.2%, Sn is 0-0.2%, RE is 0-0.5%, Cr is 0-0.3%, Cd is 0-0.3%, and Ca is 0-0.05%.

[0010] Furthermore, the molding process includes the following steps: The molten alloy is pushed into a mold and subjected to low-pressure filling casting. Once the molten alloy enters the semi-solid solidification zone, it forms a semi-solid aluminum alloy part. The semi-solid aluminum alloy part is then subjected to in-situ first-stage forging in the mold. The deformation of the semi-solid aluminum alloy part during the in-situ first-stage forging process is 5-70%.

[0011] Furthermore, the molding process also includes the following steps: After in-situ primary forging, in-situ secondary forging deformation is performed to obtain aluminum alloy parts.

[0012] Furthermore, the molding process also includes the following steps: High-strength Al-Mg alloys are obtained by heat treatment of aluminum alloy parts after in-situ primary forging or in-situ secondary forging deformation.

[0013] Furthermore, the molding process includes the following steps: The forming process includes die casting and annealing. The die casting temperature is 660-720ºC, and the die casting speed is 0.23-2.5m / s. The annealing temperature is 260-370°C, and the time is 0.1-10h. Alternatively, the forming process includes vacuum die casting and annealing. The vacuum die casting temperature is 660-700°C, the vacuum degree is 20-80mbar, the injection speed is 2-5m / s, and the casting pressure is 80-120MPa. The annealing temperature is 260-370°C, and the time is 0.1-10h.

[0014] The present invention also provides an aluminum alloy structural component, wherein at least a portion of the material of the aluminum alloy structural component is the above-mentioned high-strength Al-Mg aluminum alloy or a high-strength Al-Mg aluminum alloy prepared by the preparation method described above.

[0015] In the technical solution of this invention, the high-strength Al-Mg aluminum alloy contains 6.5-10% Mg, 0.01-0.5% Zn, 0.01-0.2% Si, 0.01-0.5% Fe, 0-0.5% Cu, 0-0.8% Mn, 0-0.2% Ti, 0-0.5% Zr, 0-0.2% V, 0-0.1% B, 0-0.1% Be, 0-0.5% Ag, and Al, as well as unavoidable impurities. The composite addition of Mg, Zn, Si, Fe, Cu, Mn, Ti, Zr, V, B, Ag and Be within the above content range interacts and influences each other, ensuring that the high-strength Al-Mg aluminum alloy has good formability and excellent mechanical properties. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] One embodiment of the present invention provides a high-strength Al-Mg aluminum alloy containing 6.5-10% Mg, 0.01-0.5% Zn, 0.01-0.2% Si, 0.01-0.5% Fe, 0-0.5% Cu, 0-0.8% Mn, 0-0.2% Ti, 0-0.5% Zr, 0-0.2% V, 0-0.1% B, 0-0.1% Be, 0-0.5% Ag, and Al, as well as unavoidable impurities.

[0018] The specific percentage of Mg by mass can be 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7.6%, 7.7%, 7.8%, 7.9%, 8%, 8.1%, 8.2%, 8.3%, 8.4%, 8.5%, 8.6%, 8.7%, 8.8%, 8.9%, 9%, 9.1%, 9.2%, 9.3%, 9.4%, 9.5%, 9.6%, 9.7%, 9.8%, 9.9%, or 10%.

[0019] The specific percentage content of Zn by mass can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%.

[0020] The specific percentage content of Si by mass can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, or 0.2%.

[0021] The specific percentage of Fe by mass can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%.

[0022] The specific percentage content of Cu by mass can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%.

[0023] The specific percentage content of Mn by mass can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, or 0.8%.

[0024] The specific mass percentage content of Ti and V can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, or 0.2%.

[0025] The specific percentage content of Zr by mass can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%.

[0026] B. The specific percentage content of Be by mass can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%.

[0027] The specific percentage content of Ag by mass can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%.

[0028] In one embodiment, the high-strength Al-Mg aluminum alloy contains 7-9% Mg, 0.05-0.5% Zn, 0.02-0.2% Si, 0.1-0.4% Fe, 0.001-0.5% Cu, 0.001-0.8% Mn, 0.001-0.2% Ti, 0.001-0.5% Zr, 0.001-0.2% V, 0.001-0.1% B, 0.001-0.1% Be, and 0.001-0.5% Ag by mass.

[0029] The mass ratio of Mn to Fe is greater than 0.4, preferably 0.45-20, and can specifically be greater than 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. Setting the mass ratio of Mn to Fe to be greater than 0.4 reduces the harmful effects of Fe and improves the mold release properties and mechanical properties of aluminum alloys through Mn.

[0030] The combined mass percentage of Mg and Zn is 7.5-10.5%, specifically 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or 10.5%. Increasing the Mg and Zn content accordingly significantly improves the strength of the aluminum alloy and prevents the precipitation of the Mg2Al3 phase, resulting in an aluminum alloy with excellent strength and elongation. Understandably, the Mg content is directly proportional to the Zn content.

[0031] The sum of the mass percentages of Si and Fe is less than 0.6%, specifically less than 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, 0.32%, 0.34%, 0.36%, 0.38%, 0.4%, 0.42%, 0.44%, 0.46%, 0.48%, 0.5%, 0.52%, 0.54%, 0.56%, 0.58%, or 0.59%. In the mold filling process of integrated casting and forging, a slow, high-pressure push is required to propel the alloy solution into the mold cavity; fluidity of the alloy solution is not required. Therefore, the sum of the mass percentages of Si and Fe can be set to less than 0.6%.

[0032] The mass percentage content of Fe is greater than that of Si, and the sum of the mass percentage contents of Si and Fe is less than 0.6%. This reduces the adverse effects of Si and Fe on the elongation of aluminum alloys, thereby reducing the occurrence of cracks in aluminum alloys during deformation, and thus obtaining thin-walled and medium-thick aluminum alloy structural parts.

[0033] The sum of the mass percentages of V and Ti is less than 0.4%, such as less than 0.3% or less than 0.2%, specifically less than 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, or 0.39%. When V and Ti are combined, their individual contents can be reduced; however, if the combined content exceeds 0.4%, a coarse second phase will form, leading to a decrease in the alloy's mechanical properties.

[0034] In the technical solution of this invention, the high-strength Al-Mg aluminum alloy contains 6.5-10% Mg, 0.01-0.5% Zn, 0.01-0.2% Si, 0.01-0.5% Fe, 0-0.5% Cu, 0-0.8% Mn, 0-0.2% Ti, 0-0.5% Zr, 0-0.2% V, 0-0.1% B, 0-0.1% Be, 0-0.5% Ag, and Al, as well as unavoidable impurities. The combined addition of Mg, Zn, Si, Fe, Cu, Mn, Ti, Zr, V, B, Ag, and Be within the above content range interacts and influences each other, ensuring that high-strength Al-Mg aluminum alloys not only have good formability but also excellent mechanical properties (such as strength and elongation). Specifically: Setting the Mg mass percentage content to 6.5-10% allows Mg dissolved in the aluminum matrix to enhance the strength of the aluminum alloy. Mg can also react with Al, Fe, Si, Cu, Zn, etc., to form second phases such as AlFeMgSi, (CuMg)Al2, AlCuMgSi, Mg2Zn, Mg2Si, and Mg2SiZn, thereby improving the tensile strength of the aluminum alloy. In the casting-forging integrated process, at least one in-situ forging treatment can prevent the precipitation of the Al3Mg2 phase when the Mg content does not exceed 3%, thus giving the aluminum alloy higher plasticity and elongation. The Zn mass percentage content... Set to 0.01-0.5%, Zn can react with Mg, Si, and Al to form highly soluble strengthening phases such as Mg2Zn, Al2Mg3Zn3, and Mg2SiZn. The formation of the Mg2SiZn phase can suppress the precipitation of coarse grain boundary Mg2Al3 phase. Furthermore, Zn can promote the precipitation of second phases such as Al3Fe, AlFeSi, AlFeSiCu, (CuMg)Al2, Mg2Zn, and Mg2SiZn, thereby improving the tensile strength of aluminum alloys. Zn can also eliminate elemental Si and Mg to reduce their influence on the properties of aluminum alloys, such as reducing the concentrations of Si and Mg. The effect of high Mg and Zn content on the elongation of aluminum alloys was investigated. Increasing the Mg and Zn content significantly improved the strength of the aluminum alloy and prevented the precipitation of the Mg2Al3 phase, resulting in an aluminum alloy with excellent strength and elongation. Setting the Si mass percentage content to 0.01-0.2% allowed the formation of the Mg2Si phase, which inhibited the precipitation of coarse grain boundary Mg2Al3 phase, significantly improving plasticity and strength, as well as enhancing the processing fluidity and die-casting performance of the aluminum alloy. Setting the Fe mass percentage content to 0.01-0.5% improved demolding performance, and Fe can also combine with Al... The reaction of aluminum alloys with Si, Cu, Ni, Mg, and Mn produces second phases such as Al3Fe, AlFeSi, AlFeSiCu, AlFeMgSiNi, AlFeSiNi, FeNiAl9, AlFeMgSi, Al6(Fe,Mn), and α-Al(FeMn)Si, thereby improving the tensile strength of aluminum alloys. Increasing the Cu content by 0-0.5% can significantly improve the tensile strength of aluminum alloys. Cu can react with Al, Fe, Si, Mg, Zn, and Mn to form Al2Cu, AlFeSiCu, Al2CuZn, and Al... 12 CuMn2、τ(Cu2Mn3Al 20 Secondary phases such as AlCuMgSi and (CuMg)Al2 are added to improve the tensile strength of aluminum alloys. Cu can also promote the formation of GP zones and MgZn2, further improving the strength of aluminum alloys. When the mass percentage content of Mn is set to 0-0.8%, Mn can react with Al, Fe, Si, and Cu to form MnAl2, MnAl6, and Al... 12CuMn2, Al3(Fe,Mn), Al6(Fe,Mn), Al 12 (Fe,Mn)3Si, α-Al(FeMn)Si, τ(Cu2Mn3Al 20 The formation of α-Al(FeMn)Si can improve the tensile strength of aluminum alloys by inhibiting the precipitation of coarse grain boundary Mg2Al3 phase and reducing the content of impurity Fe. Mn can significantly refine the grain size and improve elongation by the lattice distortion generated by solid solution in the matrix and the MnAl6 dispersed particles produced by reaction with Al. Setting the mass percentage content of Ti to 0-0.2% allows Ti to react with Al to form TiAl3 phase, which acts as a non-spontaneous nucleus during crystallization, refining the grains, second phase, and precipitated phases, thereby improving the tensile strength and elongation of aluminum alloys. Mg can also destroy the original oxide film between Ti and the aluminum matrix, promoting the formation of Al2Al3 phase between Ti and aluminum alloys. 18 Ti₂Mg₃ ternary phase is added to improve the strength of aluminum alloys. Setting the Ag mass percentage content to 0-0.5% results in the formation of a T phase ((Mg,Ag)₂Al₃) in the alloy. This phase inhibits the precipitation of coarse grain boundary Mg₂Al₃ phase and alters the aging precipitation process of Mg₂Si, refining the transition phases θ'' and θ'', and increasing the stability temperature range of the GP zone, thus significantly improving plasticity and strength. Setting the Zr mass percentage content to 0-0.5% increases the tensile strength of aluminum alloys. Zr also promotes the precipitation of second phases such as Mg₂Zn, Al₂CuZn, AlCuMgSi, and (CuMg)Al₂, reducing the solid solubility of these elements in the aluminum matrix. Zr further refines grains, second phases, and precipitated phases, further improving the elongation of the aluminum alloy. Setting the V mass percentage content to 0-0.2% allows V to react with Al to form VAl. 11Refractory compounds such as titanium dioxide (Ti) refine grains during the casting process. Titanium dioxide (V) can also refine the recrystallization structure and increase the recrystallization temperature, thereby improving the tensile strength and elongation of aluminum alloys. Setting the boron content to 0-0.1% allows it to react with transition metals (including Fe) to form compounds such as ferroboron, which can be separated from the molten aluminum alloy, thus purifying the alloy. B readily adsorbs onto the surface of the iron-rich phase, inhibiting its growth and controlling its size. It also prevents the formation of the iron-rich phase in the molten aluminum alloy. B inhibits the segregation of Ti3Al, therefore, the combined use of Ti and B yields better results. Furthermore, B refines grains, second phases, and precipitated phases, further improving the tensile strength and elongation of aluminum alloys. Elongation; Setting the mass percentage content of Be to 0-0.1% can improve the tensile strength of aluminum alloys. It can also transform the plate-like β mesophase into the relatively harmless Chinese character-shaped Be-Fe (Al8Fe2SiBe) phase and prevent the formation of needle-like β-Fe phase, thereby reducing or eliminating the adverse effects of Fe on the performance of aluminum alloys. Be can also promote the formation and precipitation of phases such as Mg2Zn, Mg2SiZn, and (CuMg)Al2, thereby reducing the solid solubility of the above elements in the aluminum matrix. Be can also form an active film on the surface of impurity element phases such as Fe, preventing the growth of impurity elements. It can also agglomerate on grain boundaries or adsorb on solid-liquid interfaces, forming supercooling, which increases the chance of dendrite melting and thus refines the grains.

[0035] In summary, the tensile strength of aluminum alloys can be significantly improved by increasing the content of Mg, Zn, Cu, Fe, Mn, and Ag as described above; the fluidity and die-casting performance of aluminum alloys can be ensured by increasing the content of Si as described above; the tensile strength and demolding performance of aluminum alloys can be improved by increasing the content of Fe as described above; the tensile strength and elongation of aluminum alloys can be improved by increasing the content of Ti, V, Mn, B, and Be as described above; Zn, Mn, Cu, B, and Be can also inhibit the precipitation of coarse grain boundary Mg2Al3 phase, thereby reducing the impact of Mg2Al3 phase on the strength and elongation of aluminum alloys; the tensile strength of aluminum alloys can be improved by increasing the content of Zr, Zn, and Be as described above, and the precipitation of second phases (such as (CuMg)Al2, Mg2Zn, Mg2SiZn, Mg2Si phases, etc.) can be promoted, thereby further improving the tensile strength and elongation of aluminum alloys. Thus, high-strength Al-Mg aluminum alloys with excellent mechanical properties and formability can be obtained.

[0036] The high-strength Al-Mg aluminum alloy also contains 0-0.2% In by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, or 0.2%. In can improve the mechanical properties of aluminum alloys. In can react with other elements to form second phases, thereby improving the mechanical properties of aluminum alloys. Specifically, In can react with Al and Cu to form second phases such as AlIn and CuIn. In addition, In can refine the grains, thereby improving the elongation of aluminum alloys.

[0037] The high-strength Al-Mg aluminum alloy also contains 0-0.5% Nb by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Nb can improve the mechanical properties of the aluminum alloy. Nb can react with other elements to form a second phase, thereby improving the mechanical properties of the aluminum alloy. Specifically, Nb can react with Ti and Al to form the TiAl-Nb phase. In addition, Nb can refine the grain size, thereby increasing the elongation of the aluminum alloy.

[0038] The high-strength Al-Mg aluminum alloy also contains 0-0.2% Bi by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, or 0.2%. Bi can improve the mechanical properties of aluminum alloys. Bi can react with other elements to form second phases, thereby improving the mechanical properties of aluminum alloys. Specifically, Bi can react with Mg and Cd to form second phases such as Mg3Bi2 and Mg3(BiCd)2.

[0039] The high-strength Al-Mg aluminum alloy also contains 0-0.5% Ge by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Ge can improve the mechanical properties of aluminum alloys. Ge can react with other elements to improve the mechanical properties of aluminum alloys. Specifically, Ge can react with Al and Si to form second phases such as Al9Ge7, Al6Ge5, Al5Ge2, Al3Ge4, and SiGe. Ge can also promote the precipitation of second phases such as Al2Cu, Mg2Zn, and Mg2SiZn, refine the precipitated phases, and reduce the solid solubility of the above elements in the aluminum matrix. Ge can also replace some Si atoms in the metastable precipitated phases. The precipitated Si-Ge phase is θ'', which provides a nucleation site and increases the density of the θ'' phase, thereby further improving the mechanical properties of the aluminum alloy.

[0040] The high-strength Al-Mg aluminum alloy also contains 0-0.5% Mo by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Mo can improve the mechanical properties of aluminum alloys. Mo can react with other elements to improve the mechanical properties of aluminum alloys. Specifically, Mo can react with Al, Si, Fe, etc., to form second phases such as AlMo, AlSiMo, and AlSiFeMo, which are dispersed phases distributed at the grain boundaries of the aluminum matrix. In addition, Mo can refine the grains and improve the morphology of Fe-containing intermetallic compounds, further improving the mechanical properties of aluminum alloys.

[0041] The high-strength Al-Mg aluminum alloy also contains 0-0.5% Ni by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Ni can refine the grains, improve the tensile strength of the aluminum alloy, and promote the precipitation of the second phase, increasing the volume fraction and dispersion of the precipitated phase.

[0042] The high-strength Al-Mg aluminum alloy also contains 0-0.5% Te by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Te can improve the mechanical properties of aluminum alloys. Te can narrow the solidification temperature range of aluminum alloys, form fine petal-like rather than dendritic primary crystals, reduce or eliminate micro-shrinkage porosity, thereby improving the mechanical properties of aluminum alloys.

[0043] The high-strength Al-Mg aluminum alloy also contains 0-0.5% Co by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. Co can refine the grains to improve the mechanical properties of the aluminum alloy, and can also react with other elements to form a second phase, further improving the mechanical properties of the aluminum alloy. Specifically, Co can react with Al, Fe, Si, etc., to form Al 15 Secondary phases include (Fe,Co)3Si2 and Al3(Fe,Co). Furthermore, Co has a refining effect on the Al3Fe phase, transforming coarse needle-like and plate-like β-Al3Fe phases into small flower-like and fine strip-like α-Al3Fe phases. 15 The (Fe,Co)3Si2 phase can also promote α-Al 15 The precipitation of the (Fe,Co)3Si2 phase further improves the mechanical properties of aluminum alloys. The combined addition of Ni and Co can effectively modify Fe and transform free Fe into the second phase. The combined addition of Co, Ni and Be can rapidly reduce their solid solubility in the alloy and increase the volume fraction of the second phase, thereby improving the mechanical properties of aluminum alloys.

[0044] The high-strength Al-Mg aluminum alloy also contains 0-0.3% Cr by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%. Cr can transform the needle-like β-Fe phase into the α-Fe phase to improve the morphology of Fe and eliminate its harmful effects. It can also easily form a dispersed phase with Fe to reduce the Fe content and mitigate its harmful effects. Cr can also hinder the nucleation and growth process of recrystallization, thereby improving the tensile strength and elongation of aluminum alloys. Various chromium-containing fine compounds formed by Cr in aluminum alloys can be redissolved in the α phase during the solid solution stage. During the natural aging stage, various Cr-containing phases, such as the α-AlCrSi dispersed phase, are dispersed and precipitated. These Cr-containing phases can serve as the nucleation sites for the heterogeneous formation of β" and θ" phases, accelerating the formation of β" and θ" phases and thus improving the tensile strength of aluminum alloys.

[0045] The high-strength Al-Mg aluminum alloy also contains 0-0.2% Sr by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, or 0.2%. Sr has the functions of refining grains and inhibiting recrystallization growth, which can improve the strength and elongation of aluminum alloys. Sr can also hinder the diffusion of Fe atoms, resulting in compositional supercooling, which causes the morphology of the Al3Fe phase to change from needle-like to flower-like, thereby eliminating the influence of Fe impurities on the alloy.

[0046] The high-strength Al-Mg aluminum alloy also contains 0-0.2% Sn by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, or 0.2%. Sn can refine grains, the second phase, and precipitated phases, thereby improving the tensile strength and elongation of the aluminum alloy. Sn can also react with Mg to form the Mg3Sn2 phase, which can further improve the strength of the aluminum alloy. The formation of the Mg3Sn2 phase can suppress the precipitation of coarse grain boundary Mg2Al3 phase.

[0047] The high-strength Al-Mg aluminum alloy also contains 0-0.5% RE by mass, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. RE can refine the alloy microstructure to improve the mechanical properties of aluminum alloys. It can also form a rare earth active film on the surface of Fe-containing phases or combine with Al, Fe, Ti and other atoms to form rare earth compounds, thereby effectively reducing the solid solution of harmful elements in the aluminum matrix. RE can also transform the elongated β-Fe phase into the spherical α-Fe phase and modify elemental Si. RE can also promote the precipitation of dispersed phases such as Al2CuMg, Al3Fe, Mg2Zn, Mg2SiZn, etc., to improve the tensile strength and elongation of aluminum alloys. RE can also refine grains, second phases and precipitated phases (e.g., it can refine Al2CuMg, Mg2Si, Al3Fe phases, etc.), further improving the tensile strength and elongation of aluminum alloys.

[0048] The sum of the mass percentages of RE and Zr is less than 1%, such as less than 0.9% or less than 0.8%, specifically less than 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1%. When RE and Zr are used together, they can effectively refine grains, second phases, and precipitates to improve the strength and elongation of aluminum alloys; the core-shell structure formed by the two, such as the L12 second phase, can significantly improve the thermal stability of aluminum alloys.

[0049] The sum of the mass percentages of Mn, Cr, Zr, and RE is less than 1.5%, such as less than 1% or less than 0.5%, specifically less than 1.4%, 1.3%, 1.2%, 1.1%, 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1%. Mn, Cr, Zr, and RE react with each other to form Al. 12 The (Mn,Cr) and Al3(RE,Zr) second phases can significantly improve the strength of aluminum alloys.

[0050] The atomic percentage of Zr and RE is 1-1.2:1, specifically 1:1, 1.1:1, or 1.2:1. At this atomic percentage, it is beneficial to form the Al3(ZrRE) phase to refine the grains, the second phase, and the precipitated phases, increasing the recrystallization temperature and further improving the tensile strength and elongation of the aluminum alloy. It also ensures sufficient Al3(ZrRE) phase to promote nucleation and increase the solid fraction during subsequent in-situ primary and secondary forging processes. Combined with the cooling steps, this increases the deformation amount in the in-situ primary and secondary forging processes, further enhancing the strength and elongation of the aluminum alloy.

[0051] The high-strength Al-Mg aluminum alloy also contains 0-0.3% Cd by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%. Cd can refine α-Al, and Cd will form a large number of Cd-vacancy clusters, promoting and accelerating the precipitation of phases such as Al2Cu, Mg2Zn, and Mg2SiZn, thereby reducing the impact of high Cu content on the elongation of the aluminum alloy.

[0052] The high-strength Al-Mg aluminum alloy also contains 0-0.5% Ca by mass, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, or 0.05%. Ca can improve the β-Fe phase to reduce the harmful effects of Fe. It can also react with Al, Cu, Zn, and Si to form second phases such as Al4Ca, Al2Ca3, AlCa2, AlCaCu, CaZn, CaAlZn, and Al2CaSi2, thereby improving the tensile strength of aluminum alloys. Ca can also refine the eutectic structure and improve the β-Fe phase. It also has a modifying effect on Al-Mg alloys, refining the Si phase. Sn can react with Al, Mg, and Sc to form second phases such as Al9Sn7, Al6Sn5, Al5Sn2, Al3Sn4, Mg2Sn, and Mg2ScSn, thereby improving the tensile strength of aluminum alloys. Sn can promote the precipitation of second phases such as Mg2Si, Mg2Zn, Mg2SiZn, and Al2Cu, thereby reducing the solid solubility of these elements in the aluminum matrix. Ca and Sn can also significantly reduce the surface tension of molten aluminum alloys, reducing or even eliminating the influence of the surface tension of the oxide film on the aluminum alloy surface, thereby improving the fluidity of aluminum alloys. The combination of Ca and RE can significantly refine the grains and the second phase, thereby improving tensile strength, fluidity, and elongation.

[0053] This invention also provides a method for preparing a high-strength Al-Mg aluminum alloy, comprising the following steps: Aluminum liquid is obtained by heating an Al source at a temperature of 750-830°C; At a temperature of 720-780°C, Mg source, Zn source, Si source, Fe source, Cu source, Mn source, Ti source, Zr source, V source, B source, Ag source and Be source are added to the aluminum liquid to obtain an alloy liquid; The alloy liquid is refined, slag removed, and formed to obtain a high-strength Al-Mg aluminum alloy. The high-strength Al-Mg aluminum alloy contains 6.5-10% Mg, 0.01-0.5% Zn, 0.01-0.2% Si, 0.01-0.5% Fe, 0-0.5% Cu, 0-0.8% Mn, 0-0.2% Ti, 0-0.5% Zr, 0-0.2% V, 0-0.1% B, 0-0.1% Be, 0-0.5% Ag, and Al, as well as unavoidable impurities.

[0054] Mg source, Zn source, Si source, Fe source, Cu source, Mn source, Ti source, Zr source, V source, B source, Ag source and Be source can be added in the form of elements or alloys.

[0055] At least one of the following sources can be added to the molten aluminum: In, Nb, Bi, Ge, Mo, Ni, Te, Co, Cr, Sr, Sn, RE, Cd, and Ca. These raw materials can also be added in elemental or intermediate alloy form.

[0056] The degassing process involves adjusting the temperature of the molten alloy to 650-780℃ and introducing an inert gas such as argon into the molten alloy using a degassing machine. Specific degassing temperatures can be 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, or 780℃. The degassing time is 10-30 minutes, specifically 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes.

[0057] The refining process involves introducing inert gases such as argon into the molten alloy using a degasser. A refining agent can be added simultaneously. The vortex formed by the degasser's rotating disc in the molten alloy allows the refining agent to be evenly mixed into the alloy. The refining agent refines the alloy microstructure, thereby improving the tensile strength and elongation of the aluminum alloy. It has the advantages of good dispersibility and low cost. The refining time is 10-30 minutes, specifically 10, 15, 20, 25, or 30 minutes. The refining temperature is 650-780℃, specifically 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, or 780℃. The refining agent contains: 5-10 parts potassium fluoroaluminate, 6-20 parts AlTi5B1 metal powder, 8-25 parts potassium titanate whisker powder, 20-40 parts sodium chloride + potassium chloride, 5-10 parts potassium nitrate, 5-10 parts potassium carbonate, and 0.5-3 parts potassium silicate.

[0058] The parting surface of the mold can undergo surface treatment to form a boron carbide layer. This layer not only improves demolding performance but also enhances the mold's wear resistance and protects against corrosion from acids, alkalis, salts, and other chemicals, as well as thermal erosion of the aluminum alloy, thus extending the mold's service life. The thickness of the boron carbide layer can range from 1 to 10 mm, specifically 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm. The surface treatment can involve mixing a boron-containing gas (such as BCl3) with a carbon-containing gas (such as CH4) to obtain a mixed gas. This mixed gas is then introduced into the cavity, and through chemical vapor deposition (CVD), the boron-containing and carbon-containing gases react chemically and deposit onto the parting surface to form the boron carbide layer. The CVD temperature is 900-1200°C, the deposition pressure is 200-500 Pa, and the carrier gas flow rate is 100-200 sccm. The boron carbide layer can increase the hardness of mold steel to 3000-4000 Hv; the boron carbide layer can reduce the affinity of the mixed melt to the mold surface, improve the demolding performance of aluminum alloy, and greatly increase the elongation of aluminum alloy; the boron carbide layer can resist the corrosion of chemicals such as acids, alkalis, and salts, and can improve the corrosion resistance of aluminum alloy; the boron carbide layer can maintain good physical and chemical properties at high temperature, and can improve the thermal stability of aluminum alloy; the boron carbide layer has an extremely low coefficient of friction, which can improve the surface smoothness of aluminum alloy and significantly reduce the wear and energy consumption of aluminum alloy products caused by mechanical friction; the boron carbide layer also has high heat transfer properties. During the instant of aluminum alloy forming, the boron carbide layer can quickly conduct away heat, increasing the heat transfer rate of the mold by 2-4 times that of ordinary molds, allowing the aluminum alloy to cool down faster.

[0059] In one embodiment, the forming process includes: die casting the alloy liquid at a temperature of 660-720ºC (i.e., conventional die casting), followed by annealing. During die casting, the die casting speed of the die casting machine is 0.23-2.5 m / s. During the die casting process, the temperature cooling rate is 50-150 K / s, specifically 50 K / s, 60 K / s, 70 K / s, 80 K / s, 90 K / s, 100 K / s, 110 K / s, 120 K / s, 130 K / s, 140 K / s, or 150 K / s. A temperature cooling rate of 50-150 K / s during die casting can suppress the formation of the β-AlFeSi phase and the Al3Mg2 phase. In the annealing process, the temperature is 260-370°C, specifically 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, or 370°C, and the time is 0.1-10 hours, specifically 0.1 hours, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours. During the annealing process, annealing can promote dislocation recovery and more uniform solid solution of the Al3Mg2 phase, thereby significantly improving the elongation of the aluminum alloy.

[0060] In another embodiment, the forming process includes: vacuum die casting the alloy liquid at a temperature of 660-700°C, followed by annealing. In the vacuum die casting process, the vacuum level is 20-80 mbar, the injection speed is 2-5 m / s, and the casting pressure is 80-120 MPa. It is understood that vacuum die casting can significantly reduce the porosity of aluminum alloy castings and increase their density, resulting in higher tensile strength and elongation of the vacuum-die-cast aluminum alloy compared to that of aluminum alloys treated with conventional die casting. During vacuum die casting, the cooling rate is 100-200 K / s, specifically 100 K / s, 110 K / s, 120 K / s, 130 K / s, 140 K / s, 150 K / s, 160 K / s, 170 K / s, 180 K / s, 190 K / s, or 200 K / s. A cooling rate of 100-200 K / s during vacuum die casting can suppress the formation of β-AlFeSi and Al3Mg2 phases. In the annealing process, the temperature is 260-370°C, specifically 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, or 370°C, and the time is 0.1-10 hours, specifically 0.1 hours, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours. During the annealing process, annealing can promote dislocation recovery and more uniform solid solution of the Al3Mg2 phase, thereby significantly improving the elongation of the aluminum alloy.

[0061] It is understandable that, despite the use of cooling treatment, die casting and vacuum die casting processes, a small amount of β-AlFeSi phase will still exist.

[0062] In another embodiment, the forming process includes the following steps: molten alloy is pushed into a mold for low-pressure filling casting; once the molten alloy enters the semi-solid solidification zone to form a semi-solid aluminum alloy part, the semi-solid aluminum alloy part is subjected to in-situ primary forging in the mold, wherein the deformation of the semi-solid aluminum alloy part during the primary forging is 5-70%. The aluminum alloy part after the primary forging can also undergo in-situ secondary forging deformation to obtain another aluminum alloy part. The deformation of the semi-solid aluminum alloy part during the secondary forging is 10-70%. The aluminum alloy part after either the primary or secondary forging can be heat-treated (e.g., annealed) to obtain a high-strength Al-Mg aluminum alloy. Preferably, the deformation of the semi-solid aluminum alloy part during the primary forging is greater than the deformation during the secondary forging. In this embodiment, when the Mg content is 6.5-10%, the casting and forging integral forming process can suppress the generation of Al3Mg2 phase, and coarse Al3Mg2 phase will not appear at the grain boundaries.

[0063] It is understandable that the above forming process steps can be selected according to needs, and this application does not impose any restrictions on this. For example, aluminum alloy parts can be obtained after only performing in-situ primary forging. The aluminum alloy parts after in-situ primary forging can also be heat-treated. Alternatively, in-situ primary forging and in-situ secondary forging deformation can be performed sequentially. Furthermore, heat treatment can be performed after in-situ primary forging and in-situ secondary forging deformation.

[0064] In low-pressure filling casting, the filling speed (i.e., the moving speed of the punch) is 0.1-1.2 m / s, the filling time (i.e., the time required for the molten alloy to completely fill the mold) is 2-20 s, the casting pressure is 0.1-40 MPa, the holding time is 2-10 s (i.e., the time to maintain the molten alloy under a certain pressure after it has completely filled the mold), the mold temperature is 180-250℃, and the alloy casting temperature (i.e., the temperature when the molten alloy is filled into the mold) is 660-720℃.

[0065] A filling speed of 0.1-1.2 m / s increases the fluidity of the molten alloy, facilitating its full filling of the cavity. At this speed, the pressure applied by the punch to the molten alloy is also relatively low (specific pressure approximately 50-200 MPa), preventing casting defects such as porosity, shrinkage cavities, and looseness in the aluminum alloy product. It also avoids splashing and turbulence caused by excessively fast filling speeds, which can lead to casting defects such as oxide inclusions and air entrapment. Specific filling speeds can be 0.1 m / s, 0.2 m / s, 0.3 m / s, 0.4 m / s, 0.5 m / s, 0.6 m / s, 0.7 m / s, 0.8 m / s, 0.9 m / s, 1 m / s, 1.05 m / s, 1.1 m / s, 1.15 m / s, or 1.2 m / s. Specific filling times can be 2 s, 5 s, 10 s, 15 s, or 20 s.

[0066] Under casting pressures ranging from 0.1 to 40 MPa, the molten alloy is relatively stable and can solidify in a directional sequence. The precipitated phases within the semi-solid aluminum alloy parts are perpendicular to the basal surface of the aluminum alloy matrix. When the molten alloy solidifies stably, there are fewer pores, looseness, and cracks in the semi-solid aluminum alloy parts. Specific casting pressures can be 0.1 MPa, 0.5 MPa, 1 MPa, 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, or 40 MPa.

[0067] Semi-solid aluminum alloy parts can be formed within a holding time of 2-10 seconds and a casting pressure of 0.1-40 MPa. Moreover, high-strength Al-Mg aluminum alloys have a wide solidification range, which easily leads to casting defects such as low density and a large number of inclusions, as well as hot and cold cracking problems. Within the low casting pressure range of 0.1-40 MPa, the above-mentioned casting defects can be solved, as well as the porosity problem of high-pressure casting.

[0068] As the holding time and casting pressure increase, the casting structure inside the semi-solid aluminum alloy parts gradually becomes uniform and dense. If the holding time exceeds 10 seconds or the casting pressure is too high, the liquid phase inside the mold will completely solidify, and the semi-solid aluminum alloy parts cannot be formed. The holding time can be 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, or 10s.

[0069] The low-pressure filling casting process of this invention requires lower casting and mold preheating temperatures, which not only reduces thermal shock corrosion to the mold but also saves energy. The mold temperature can specifically be 180°C, 200°C, or 250°C. The alloy casting temperature can specifically be 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, or 720°C.

[0070] In semi-solid aluminum alloy parts, the solid-liquid ratio, or solid phase fraction, is 20-90%, specifically 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%. At this solid-liquid ratio, there are fewer casting defects in semi-solid aluminum alloy parts, and the precipitated phases within them solidify almost entirely vertically.

[0071] In the in-situ primary forging process, the forging temperature (i.e., the temperature of the semi-solid aluminum alloy parts in the mold) is 530-610℃, the forging specific pressure is 50-300MPa, the forging start time (i.e., the time interval between the formation of the semi-solid aluminum alloy parts and the in-situ primary forging process) is 2-20s, the holding time is 2-20s, and the deformation is 5-70%. After this in-situ primary forging process, the semi-solid aluminum alloy parts are transformed into solid parts.

[0072] Setting the forging temperature to 530-610℃ ensures the alloy remains in a semi-solid state. Specific forging temperatures can be 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, or 610℃. Specific forging pressures can be 50MPa, 60MPa, 70MPa, 80MPa, 90MPa, 100MPa, 120MPa, 140MPa, 160MPa, 180MPa, 200MPa, 220MPa, 240MPa, 260MPa, 280MPa, or 300MPa. The specific forging start time can be 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s, or 20s. The specific pressure holding time can be 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s, or 20s.

[0073] With a deformation amount of 5-70%, semi-solid aluminum alloy parts can be transformed into solid aluminum alloy parts after in-situ primary forging. As the deformation amount increases, the volume fraction of Al2CuMg precipitates in the solid aluminum alloy parts gradually increases, while the volume fraction of Al2Cu phase gradually decreases, thereby improving the mechanical properties of the aluminum alloy (including tensile strength and elongation). The preferred deformation amount is 20-60%, with the precipitates being essentially perpendicular to the basal plane, significantly improving the alloy's mechanical properties (including tensile strength and elongation). Specific deformation amounts can be 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, or 70%.

[0074] In this in-situ primary forging process, the semi-solid aluminum alloy parts are not cooled, removed from the mold, and then placed in the forging device for reheating to the forging temperature. Instead, the semi-solid aluminum alloy parts are directly subjected to in-situ primary forging in the original mold without the need for cooling and reheating. This allows the solid-liquid mixed phases present in the semi-solid aluminum alloy parts to deform and solidify uniformly in the in-situ primary forging process on the basis of low-pressure filling casting (without cooling to room temperature before reheating and forging, the deformation during cooling and heating is uncontrollable and it is difficult to maintain the semi-solid state). This further eliminates casting defects in the semi-solid aluminum alloy parts, significantly refines the coarse grains and the second-phase as-cast structure, refines the size of the precipitates, and introduces a large number of nano-sized precipitates inside the grains. The volume fraction of the precipitates gradually increases, thereby improving the mechanical properties of the alloy.

[0075] To improve the smooth transition between low-pressure filling casting and in-situ primary forging, a first cooling process is performed during low-pressure filling casting. This ensures that semi-solid aluminum alloy parts with a temperature of 530-610℃ are obtained immediately after pressure holding, allowing for faster entry into the in-situ primary forging process. Alternatively, if the first cooling process during low-pressure filling casting does not result in a semi-solid aluminum alloy part with a solid fraction of 20-90% after pressure holding (e.g., the solid fraction is below 20%), a semi-solid aluminum alloy part with a temperature of 530-610℃ (solid fraction of 20-90%) can be obtained by undergoing a forging start-up time. Alternatively, a second cooling process during the forging start-up time and in-situ primary forging can also achieve a semi-solid aluminum alloy part with a temperature of 530-610℃ (solid fraction of 20-90%). A circulating oil circuit, such as a 3D contour cooling circuit, can be configured for cooling and temperature control.

[0076] In low-pressure filling casting, the cooling rate for the first cooling process is 1-50℃ / s, specifically 1℃ / s, 5℃ / s, 10℃ / s, 15℃ / s, 20℃ / s, 25℃ / s, 30℃ / s, 35℃ / s, 40℃ / s, 45℃ / s, or 50℃ / s. In in-situ primary forging, the cooling rate for the second cooling process is 5-60℃ / s, specifically 5℃ / s, 10℃ / s, 15℃ / s, 20℃ / s, 25℃ / s, 30℃ / s, 35℃ / s, 40℃ / s, 45℃ / s, 50℃ / s, 55℃ / s, or 60℃ / s.

[0077] In in-situ two-stage forging deformation treatment, the forging temperature is 25-350℃, the forging specific pressure is 50-500MPa, the holding time is 0-10s, and the deformation is 10-70%. The deformation of semi-solid aluminum alloy parts in in-situ one-stage forging treatment is greater than that of solid aluminum alloy parts in in-situ two-stage forging deformation treatment. The deformation of semi-solid aluminum alloy parts in in-situ one-stage forging treatment is 0.0625-35 times that of solid aluminum alloy parts in in-situ two-stage forging deformation treatment.

[0078] The specific forging temperature can be 25℃, 30℃, 50℃, 100℃, 150℃, 200℃, 250℃, 300℃, or 350℃. Temperatures below 25℃ can cause aluminum alloy parts to easily fracture, while temperatures above 350℃ can easily lead to complete recrystallization, resulting in excessively large grain and precipitated phase sizes, which is also unfavorable for twin formation and leads to a reduction in mechanical properties.

[0079] The forging specific pressure can be 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 120 MPa, 140 MPa, 160 MPa, 180 MPa, 200 MPa, 220 MPa, 240 MPa, 260 MPa, 280 MPa, 300 MPa, 320 MPa, 340 MPa, 360 MPa, 380 MPa, 400 MPa, 420 MPa, 440 MPa, 460 MPa, 480 MPa, or 500 MPa. The forging specific pressure in the in-situ secondary forging deformation treatment is preferably greater than that in the in-situ primary forging treatment to further promote the refinement of the precipitated phase size. In one embodiment, the forging specific pressure of the in-situ secondary forging deformation treatment is 0.02-16 times that of the in-situ primary forging treatment, specifically 0.02 times, 0.1 times, 0.5 times, 1 time, 5 times, 10 times, 15 times, or 16 times.

[0080] The holding time can be 0s, 1s, 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, or 10s. For example, after in-situ primary forging, when the parameter requirements of in-situ secondary forging deformation are met, the pressure can be held for a certain period of time (e.g., 2s). For example, when the parameters reach the in-situ secondary forging deformation, the in-situ secondary forging deformation can be stopped immediately, and subsequent heat treatment can be carried out; this holding time can be 0s. For example, when the parameters reach the in-situ secondary forging deformation, the pressure can be held for 5s before subsequent heat treatment.

[0081] The deformation amount can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, or 70%.

[0082] The deformation amount in in-situ primary forging is 0.0625-35 times that in in-situ secondary forging deformation. Specifically, it can be 0.0625 times, 0.1 times, 0.5 times, 1 times, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 13 times, 14 times, 15 times, 16 times, 17 times, 18 times, 19 times, 20 times, 21 times, 22 times, 23 times, 24 times, 25 times, 26 times, 27 times, 28 times, 29 times, 30 times, 31 times, 32 times, 33 times, 34 times, or 35 times. The casting defects in semi-solid aluminum alloy parts can be effectively eliminated and the grains and second-phase as-cast structure can be refined in the first in-situ forging process. A large number of nano-scale precipitates appear inside the grains. The precipitates are further refined in the second in-situ forging deformation process, thereby obtaining an aluminum alloy with excellent mechanical properties.

[0083] In in-situ primary forging and in-situ secondary forging deformation processes, when the deformation amount is large, Ag can be dissolved in strengthening phases (such as AlFeMgSi, (CuMg)Al2, AlCuMgSi, Mg2Zn, Mg2Si, Mg2SiZn, etc.) to significantly improve the strength of aluminum alloys, which allows the Ag content of this application to reach 0.5%.

[0084] In the in-situ primary forging process, the molten aluminum alloy gradually transforms into a semi-solid state, and the nucleus content increases accordingly. A higher nucleus content results in a higher solid fraction. The Al3(RE,Zr) phase formed by Zr reacting with Al and RE is conducive to nucleus formation. In this application, the Zr and RE content can reach 0.5% to ensure sufficient Al3(RE,Zr) phase presence, thereby increasing the solid fraction. The relatively high cooling rates of the in-situ primary forging and secondary forging deformation processes prevent Al3(RE,Zr) phase coarsening, avoiding adverse effects on the strength and elongation of the aluminum alloy when the Zr and RE content is high. Moreover, the in-situ primary forging process and the in-situ secondary forging deformation process of this application are performed in "in-situ" (which can be understood as the two forging processes being carried out in the same location without being moved to other locations). Compared with the non-"in-situ" forming technology in the prior art (which requires reheating and homogenization after casting), the grains are less likely to grow. Combined with a larger cooling rate and a higher solid fraction, the in-situ primary forging process and the in-situ secondary forging deformation process of this application can have a larger deformation amount.

[0085] Preferably, the content of Zr and RE is 0.1-0.5%.

[0086] Understandably, the mold is an integrated casting and forging mold. The punch, driven by a feed rod, pushes the mixture into the mold cavity for casting and forging. During low-pressure filling casting, the filling speed and time can be adjusted by regulating the punch speed. The downward pressure of the punch during filling generates filling injection force, and the stroke of the punch after filling generates boosting pressure. These filling injection force and boosting pressure can be used to regulate the casting pressure during the casting process. In subsequent in-situ primary forging and in-situ secondary forging deformation processes, the forging pressure can also be adjusted by regulating the punch stroke.

[0087] To improve the smoothness of the connection between the in-situ primary forging process and the in-situ secondary forging deformation process, a second cooling process was carried out during the in-situ primary forging process. This process ensures that solid aluminum alloy parts with a temperature of 25-350℃ are obtained as soon as possible after the pressure holding is completed, so that they can enter the in-situ secondary forging deformation process as soon as possible.

[0088] The high dislocation density generated by the pre-formed twins through in-situ secondary forging pre-deformation treatment provides more diffusion pathways for the dissolution of Mg, Cu, Zn, Si, Fe, Ag, and Mn solute atoms in the aluminum matrix, promotes the nucleation of precipitates, accelerates the formation of precipitates, enhances the hardening response of the alloy, and further refines the grain size.

[0089] A third cooling process was performed during the in-situ secondary forging deformation to facilitate the formation of twins. The cooling rate for this third cooling process in the in-situ secondary forging deformation was 20-60℃ / s, specifically 20℃ / s, 25℃ / s, 30℃ / s, 35℃ / s, 40℃ / s, 45℃ / s, 50℃ / s, 55℃ / s, or 60℃ / s. Cooling treatment was performed during the low-pressure filled casting, in-situ primary forging, and in-situ secondary forging deformation processes. After these processes, the precipitation of Mg2Zn, Mg2Si, Mg2SiZn, AlCuMgSi, and Al2CuMg phases was promoted, and the proportion of Al2CuMg precipitates gradually increased. This suppressed the formation of coarse Al2Cu phases, improved the tensile strength of the aluminum alloy, and prevented excessive Al2Cu phase from reducing the elongation of the aluminum alloy.

[0090] In one embodiment, the heat treatment is annealing. During annealing, the temperature is 260-370°C, specifically 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, or 370°C, and the time is 0.1-10 hours, specifically 0.1 hours, 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours. During annealing, dislocation recovery, rearrangement, and even complete recrystallization are promoted, resulting in more uniform solid solution and significantly improving the elongation of the aluminum alloy.

[0091] In this invention, an alloy liquid containing Mg, Zn, Si, Fe, Cu, Mn, Ti, Zr, V, B, Ag, and Be elements is refined, degassed, and formed to obtain a high-strength Al-Mg aluminum alloy. The composite addition of Mg, Zn, Si, Fe, Cu, Mn, Ti, Zr, V, B, Ag, and Be within the aforementioned content range interacts and influences each other, resulting in superior mechanical properties for the high-strength Al-Mg aluminum alloy. The alloy liquid may further contain at least one source selected from In, Nb, Bi, Ge, Mo, Ni, Te, Co, Cr, Sr, Sn, RE, Cd, and Ca.

[0092] During the forming process, the molten alloy is pushed into the mold by a punch for low-pressure filling casting. Once the molten alloy enters the semi-solid solidification zone, the semi-solid aluminum alloy part undergoes in-situ first-stage forging and second-stage forging deformation processes with large deformation amounts within the mold, resulting in the aluminum alloy part. The part is then heat-treated to obtain the final aluminum alloy product. This aluminum alloy product possesses not only the structural complexity of cast products but also the high strength and toughness of deformed products. By eliminating the need to remove the semi-solid aluminum alloy part from the low-pressure filling casting mold and place it into the subsequent multi-stage forging mold, the aluminum alloy preparation method of this invention offers advantages such as fewer process steps, shorter production cycle, higher production efficiency, and lower cost. During the low-pressure filling casting process, casting defects within the aluminum alloy part are minimal. During the in-situ primary forging process with large deformation, casting defects inside the semi-solid aluminum alloy parts are further eliminated, and the coarse grains and second-phase as-cast structure are significantly refined. A large number of nanoscale precipitates appear within the grains, their size is refined, and their volume fraction is increased, thus improving the mechanical properties of the alloy (including tensile strength and elongation). During the in-situ secondary forging pre-deformation process, the grain size can be further refined. Furthermore, the high dislocation density generated by pre-formed twins provides more diffusion pathways for the dissolution of Mg, Cu, Zn, Si, Fe, Ag, and Mn solute atoms in the aluminum matrix during subsequent heat treatment. This promotes the nucleation of precipitates, enhances the alloy's hardening response, accelerates precipitate formation, and further increases the volume fraction of precipitates, thereby improving the alloy's mechanical properties.

[0093] This invention also provides an aluminum alloy structural component, at least a portion of which is made of the aforementioned high-strength Al-Mg aluminum alloy or a high-strength Al-Mg aluminum alloy prepared by the same method. The aluminum alloy structural component possesses excellent mechanical properties and elongation, and can be applied in aerospace, automotive and transportation, military and weaponry, mold and machinery manufacturing, and special high-temperature structural components. Since this aluminum alloy structural component employs all the technical solutions of all embodiments of the aforementioned high-strength Al-Mg aluminum alloy, it possesses at least all the beneficial effects brought about by the technical solutions of the aforementioned embodiments, which will not be elaborated upon here.

[0094] For aluminum alloy structural components, the mechanical properties decrease sharply with increasing thickness. However, the aluminum alloy of this invention, when using an integrated casting and forging process, maintains good mechanical properties even when its thickness is greater than 3mm and further greater than 5mm. Furthermore, when using die casting and vacuum die casting processes, the aluminum alloy of this invention maintains good mechanical properties even when its thickness is greater than 2mm.

[0095] Example Please refer to Table 1 for the composition and content of the aluminum alloys in Examples 1 to 13, and Table 2 for the performance test results.

[0096] Table 1. Composition and content of aluminum alloys in Examples 1 to 13 For the sake of simplicity, the content of trace elements such as impurities in the examples is not shown.

[0097] When preparing the aluminum alloys of Examples 1 to 14, the preparation methods of these aluminum alloys differ in the types and contents of elements, as well as in the forming process. Other steps, such as Al source heating temperature, refining process, and degassing process, can be the same.

[0098] In preparing the Al-Mg integrated cast-forged aluminum alloy of Example 1, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging deformation, and annealing. In the low-pressure filling casting, the filling speed was 0.1 m / s, the filling time was 20 s, the casting pressure was 0.2 MPa, the holding time was 2 s, the mold temperature was 200℃, the alloy casting temperature was 660℃, and the cooling rate was 5℃ / s. In the in-situ primary forging, the forging temperature was 600℃, the forging specific pressure was 60 MPa, the forging start time was 2 s, the holding time was 10 s, the cooling rate was 25℃ / s, and the deformation was 10%. In the in-situ secondary forging deformation, the forging temperature was 250℃, the forging specific pressure was 110 MPa, the holding time was 2 s, the cooling rate was 50℃ / s, and the deformation was 40%. In the annealing, the temperature was 300℃, and the time was 3 h.

[0099] In preparing the Al-Mg integrated cast-forged aluminum alloy of Example 2, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging deformation, and annealing. In the low-pressure filling casting, the filling speed was 0.2 m / s, the filling time was 15 s, the casting pressure was 0.5 MPa, the holding time was 2 s, the mold temperature was 200℃, the alloy casting temperature was 660℃, and the cooling rate was 5℃ / s. In the in-situ primary forging, the forging temperature was 610℃, the forging specific pressure was 300 MPa, the forging start time was 2 s, the holding time was 10 s, the cooling rate was 20℃ / s, and the deformation was 60%. In the in-situ secondary forging deformation, the forging temperature was 210℃, the forging specific pressure was 120 MPa, the holding time was 5 s, the cooling rate was 30℃ / s, and the deformation was 30%. During the annealing process, the temperature was 280℃ and the time was 2 hours.

[0100] In preparing the Al-Mg integrated cast-forged aluminum alloy of Example 3, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging deformation, and annealing. In the low-pressure filling casting, the filling speed was 0.6 m / s, the filling time was 10 s, the casting pressure was 40 MPa, the holding time was 2 s, the mold temperature was 250℃, the alloy casting temperature was 720℃, and the cooling rate was 10℃ / s. In the in-situ primary forging, the forging temperature was 600℃, the forging specific pressure was 300 MPa, the forging start time was 2 s, the holding time was 4 s, the cooling rate was 50℃ / s, and the deformation was 40%. In the in-situ secondary forging deformation, the forging temperature was 200℃, the forging specific pressure was 80 MPa, the holding time was 1 s, the cooling rate was 20℃ / s, and the deformation was 50%. In the annealing, the temperature was 300℃, and the time was 1 h.

[0101] In preparing the Al-Mg integrated cast-forged aluminum alloy of Example 4, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging deformation, and annealing. In the low-pressure filling casting, the filling speed was 0.5 m / s, the filling time was 12 s, the casting pressure was 35 MPa, the holding time was 3 s, the mold temperature was 210℃, the alloy casting temperature was 660℃, and the cooling rate was 10℃ / s. In the in-situ primary forging, the forging temperature was 550℃, the forging specific pressure was 280 MPa, the forging start time was 2 s, the holding time was 5 s, the cooling rate was 40℃ / s, and the deformation was 30%. In the in-situ secondary forging deformation, the forging temperature was 250℃, the forging specific pressure was 120 MPa, the holding time was 1 s, the cooling rate was 30℃ / s, and the deformation was 10%. In the annealing, the temperature was 350℃, and the time was 2 h.

[0102] In preparing the Al-Mg integrated cast-forged aluminum alloy of Example 5, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging deformation, and annealing. In the low-pressure filling casting, the filling speed was 1.1 m / s, the filling time was 3 s, the casting pressure was 3 MPa, the holding time was 2 s, the mold temperature was 250℃, the alloy casting temperature was 720℃, and the cooling rate was 40℃ / s. In the in-situ primary forging, the forging temperature was 540℃, the forging specific pressure was 120 MPa, the forging start time was 2 s, the holding time was 10 s, the cooling rate was 40℃ / s, and the deformation was 30%. In the in-situ secondary forging deformation, the forging temperature was 60℃, the forging specific pressure was 150 MPa, the holding time was 1 s, the cooling rate was 20℃ / s, and the deformation was 30%. In the annealing, the temperature was 370℃, and the time was 5 h.

[0103] In preparing the Al-Mg integrated cast-forged aluminum alloy of Example 6, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging deformation, and annealing. In the low-pressure filling casting, the filling speed was 1.1 m / s, the filling time was 3 s, the casting pressure was 5 MPa, the holding time was 2 s, the mold temperature was 180℃, the alloy casting temperature was 710℃, and the cooling rate was 30℃ / s. In the in-situ primary forging, the forging temperature was 610℃, the forging specific pressure was 140 MPa, the forging start time was 2 s, the holding time was 20 s, the cooling rate was 20℃ / s, and the deformation was 25%. In the in-situ secondary forging deformation, the forging temperature was 110℃, the forging specific pressure was 160 MPa, the holding time was 1 s, the cooling rate was 20℃ / s, and the deformation was 60%. In the annealing, the temperature was 280℃, and the time was 4 h.

[0104] In preparing the Al-Mg integrated cast-forged aluminum alloy of Example 7, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging deformation, and annealing. In the low-pressure filling casting, the filling speed was 1 m / s, the filling time was 5 s, the casting pressure was 15 MPa, the holding time was 2 s, the mold temperature was 200℃, the alloy casting temperature was 710℃, and the cooling rate was 5℃ / s. In the in-situ primary forging, the forging temperature was 600℃, the forging specific pressure was 80 MPa, the forging start time was 2 s, the holding time was 11.5 s, the cooling rate was 50℃ / s, and the deformation was 10%. In the in-situ secondary forging deformation, the forging temperature was 25℃, the forging specific pressure was 500 MPa, the holding time was 5 s, the cooling rate was 60℃ / s, and the deformation was 70%. In the annealing, the temperature was 260℃, and the time was 2 h.

[0105] In preparing the Al-Mg integrated cast-forged aluminum alloy of Example 8, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging deformation, and annealing. In the low-pressure filling casting, the filling speed was 0.8 m / s, the filling time was 10 s, the casting pressure was 20 MPa, the holding time was 5 s, the mold temperature was 200℃, the alloy casting temperature was 700℃, and the cooling rate was 10℃ / s. In the in-situ primary forging, the forging temperature was 550℃, the forging specific pressure was 60 MPa, the forging start time was 2 s, the holding time was 7 s, the cooling rate was 50℃ / s, and the deformation was 10%. In the in-situ secondary forging deformation, the forging temperature was 200℃, the forging specific pressure was 120 MPa, the holding time was 10 s, the cooling rate was 30℃ / s, and the deformation was 20%. In the annealing, the temperature was 300℃, and the time was 5 h.

[0106] In preparing the Al-Mg integrated cast-forged aluminum alloy of Example 9, the forming process included low-pressure filling casting, in-situ primary forging, and in-situ secondary forging deformation and annealing. In the low-pressure filling casting, the filling speed was 1 m / s, the filling time was 5 s, the casting pressure was 10 MPa, the holding time was 2 s, the mold temperature was 210℃, the alloy casting temperature was 700℃, and the cooling rate was 10℃ / s. In the in-situ primary forging, the forging temperature was 600℃, the forging specific pressure was 60 MPa, the forging start time was 2 s, the holding time was 10 s, the cooling rate was 40℃ / s, and the deformation was 10%. In the in-situ secondary forging deformation and annealing, the temperature was 310℃, and the time was 2 h.

[0107] In preparing the Al-Mg integrated cast-forged aluminum alloy of Example 10, the forming process included low-pressure filling casting, in-situ primary forging, in-situ secondary forging deformation, and annealing. In the low-pressure filling casting, the filling speed was 0.1 m / s, the filling time was 20 s, the casting pressure was 0.2 MPa, the holding time was 2 s, the mold temperature was 200℃, the alloy casting temperature was 690℃, and the cooling rate was 5℃ / s. In the in-situ primary forging, the forging temperature was 580℃, the forging specific pressure was 60 MPa, the forging start time was 2 s, the holding time was 6 s, the cooling rate was 50℃ / s, and the deformation was 10%. In the in-situ secondary forging deformation, the forging temperature was 280℃, the forging specific pressure was 110 MPa, the holding time was 2 s, the cooling rate was 50℃ / s, and the deformation was 40%. In the annealing, the temperature was 310℃, and the time was 5 h.

[0108] In preparing the high-strength Al-Mg aluminum alloy of Example 11, the forming process included: die casting the alloy liquid at 680ºC, followed by annealing. During die casting, the die casting speed was 0.8 m / s and the cooling rate was 60 K / s. During annealing, the temperature was 260°C and the time was 5 hours.

[0109] In preparing the Al-Mg vacuum die-cast aluminum alloy of Example Twelve, the forming process included: vacuum die casting of the alloy liquid at a temperature of 660ºC, followed by annealing. During vacuum die casting, the vacuum level was 80 mbar, the injection speed was 4 m / s, the casting pressure was 120 MPa, and the cooling rate was 120 K / s. During annealing, the temperature was 300 °C, and the time was 2 hours.

[0110] In preparing the high-strength Al-Mg aluminum alloy of Example Thirteen, the forming process included: die casting the alloy liquid at 710ºC, followed by annealing. During die casting, the die casting speed was 1.2 m / s, and the cooling rate was 90 K / s. During annealing, the temperature was 300 °C, and the time was 2 hours.

[0111] In preparing the Al-Mg vacuum die-cast aluminum alloy of Example Fourteen, the forming process included: vacuum die-casting the alloy liquid at a temperature of 680ºC, followed by annealing. During vacuum die-casting, the vacuum level was 50 mbar, the injection speed was 5 m / s, the casting pressure was 100 MPa, and the cooling rate was 100 K / s. During annealing, the temperature was 280 °C, and the time was 3 hours.

[0112] Table 2 Performance test results of aluminum alloys in Examples 1 to 14 Referring to Table 2, the high-strength Al-Mg aluminum alloys of Examples 1 to 14 exhibit excellent tensile strength and elongation. Specifically, the Al-Mg cast-forged aluminum alloys of Examples 1 to 10 have a tensile strength of not less than 290 MPa and an elongation of not less than 7.5%; the Al-Mg die-cast aluminum alloys of Examples 11 and 12 have a tensile strength of not less than 270 MPa and an elongation of not less than 8.5%; and the Al-Mg vacuum die-cast aluminum alloys of Examples 13 and 14 have a tensile strength of not less than 280 MPa and an elongation of not less than 7%. This indicates that the high-strength Al-Mg aluminum alloys of the present invention possess superior mechanical properties. Furthermore, the Al-Mg cast-forged aluminum alloys of Examples 1 to 10 maintain superior mechanical properties even when their thickness is greater than 3.5 mm. The high-strength Al-Mg aluminum alloys of Examples 11 to 14 also exhibit superior mechanical properties when their thickness is greater than 2 mm.

[0113] In summary, the tensile strength of the Al-Mg series cast-forged aluminum alloy of the present invention is not less than 290 MPa and the elongation is not less than 7.5%; the tensile strength of the Al-Mg series die-cast aluminum alloy of the present invention is not less than 270 MPa and the elongation is not less than 8.5%; the tensile strength of the Al-Mg series vacuum die-cast aluminum alloy of the present invention is not less than 280 MPa and the elongation is not less than 7%.

[0114] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the content of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A high-strength Al-Mg aluminum alloy, characterized in that, The high-strength Al-Mg aluminum alloy contains 6.5-10% Mg, 0.01-0.5% Zn, 0.01-0.2% Si, 0.01-0.5% Fe, 0-0.5% Cu, 0-0.8% Mn, 0-0.2% Ti, 0-0.5% Zr, 0-0.2% V, 0-0.1% B, 0-0.1% Be, 0-0.5% Ag, and Al, as well as unavoidable impurities.

2. The high-strength Al-Mg aluminum alloy according to claim 1, characterized in that, The high-strength Al-Mg aluminum alloy contains 7-9% Mg, 0.05-0.5% Zn, 0.02-0.2% Si, 0.1-0.4% Fe, 0.001-0.5% Cu, 0.001-0.8% Mn, 0.001-0.2% Ti, 0.001-0.5% Zr, 0.001-0.2% V, 0.001-0.1% B, 0.001-0.1% Be, and 0.001-0.5% Ag by mass.

3. The high-strength Al-Mg aluminum alloy according to claim 1, characterized in that, At least one of the following conditions must be met: The sum of the mass percentages of Mg and Zn is 7.5-10.5%; The mass ratio of Mn to Fe is greater than 0.4; The sum of the mass percentages of Si and Fe is less than 0.6%; The sum of the mass percentage contents of V and Ti is less than 0.4%.

4. The high-strength Al-Mg aluminum alloy according to claim 1, characterized in that, The high-strength Al-Mg aluminum alloy further contains at least one of In, Nb, Bi, Ge, Mo, Ni, Te, Co, Cr, Sr, Sn, RE, Cd, and Ca, wherein the mass percentage content of In is 0-0.2%, the mass percentage content of Nb is 0-0.5%, the mass percentage content of Bi is 0-0.2%, the mass percentage content of Ge is 0-0.5%, the mass percentage content of Mo is 0-0.5%, the mass percentage content of Ni is 0-0.5%, the mass percentage content of Te is 0-0.5%, the mass percentage content of Co is 0-0.5%, the mass percentage content of Cr is 0-0.3%, the mass percentage content of Sr is 0-0.2%, the mass percentage content of Sn is 0-0.2%, the mass percentage content of RE is 0-0.5%, the mass percentage content of Cd is 0-0.3%, and the mass percentage content of Ca is 0-0.05%.

5. A method for preparing a high-strength Al-Mg aluminum alloy, comprising the following steps: The Al source is subjected to a first heating treatment to obtain molten aluminum. Add Mg source, Zn source, Si source, Fe source, Cu source, Mn source, Ti source, Zr source, V source, B source, Ag source and Be source to the aluminum liquid, and perform a second heating treatment to obtain alloy liquid; The alloy liquid is refined, slag removed, and formed to obtain a high-strength Al-Mg aluminum alloy. The high-strength Al-Mg aluminum alloy contains 6.5-10% Mg, 0.01-0.5% Zn, 0.01-0.2% Si, 0.01-0.5% Fe, 0-0.5% Cu, 0-0.8% Mn, 0-0.2% Ti, 0-0.5% Zr, 0-0.2% V, 0-0.1% B, 0-0.1% Be, 0-0.5% Ag, and Al, as well as unavoidable impurities.

6. The method for preparing high-strength Al-Mg aluminum alloy according to claim 5, characterized in that, The molding process includes the following steps: The molten alloy is pushed into a mold and subjected to low-pressure filling casting. Once the molten alloy enters the semi-solid solidification zone, it forms a semi-solid aluminum alloy part. The semi-solid aluminum alloy part is then subjected to in-situ first-stage forging in the mold. The deformation of the semi-solid aluminum alloy part during the in-situ first-stage forging process is 5-70%.

7. The method for preparing high-strength Al-Mg aluminum alloy according to claim 6, characterized in that, The molding process also includes the following steps: After in-situ primary forging, in-situ secondary forging deformation is performed to obtain aluminum alloy parts.

8. The method for preparing high-strength Al-Mg aluminum alloy according to claim 6 or 7, characterized in that, The molding process also includes the following steps: High-strength Al-Mg alloys are obtained by heat treatment of aluminum alloy parts after in-situ primary forging or in-situ secondary forging deformation.

9. The method for preparing high-strength Al-Mg aluminum alloy according to claim 5, characterized in that, The molding process includes the following steps: The forming process includes die casting and annealing. The die casting temperature is 660-720ºC, and the die casting speed is 0.23-2.5 m / s. The annealing temperature is 260-370°C, and the annealing time is 0.1-10 h. The forming process includes vacuum die casting and annealing. The vacuum die casting process has a temperature of 660-700°C, a vacuum degree of 20-80 mbar, an injection speed of 2-5 m / s, and a casting pressure of 80-120 MPa. The annealing process has a temperature of 260-370°C and a time of 0.1-10 h.

10. An aluminum alloy structural component, characterized in that, At least a portion of the aluminum alloy structural component is made of a high-strength Al-Mg aluminum alloy as described in any one of claims 1 to 4 or a high-strength Al-Mg aluminum alloy prepared by any one of claims 5 to 9.

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