Heat-treatment-free die-casting aluminum alloy for structural part and die casting preparation method

Abstract

The invention discloses a heat treatment-free die-casting aluminum alloy for a structural part. The heat treatment-free die-casting aluminum alloy comprises the following components in percentage by mass: 7.5%-11.5% of Si, less than or equal to 0.2% of Fe, 0.6%-1.2% of Mg, 0.05%-0.8% of Mn, 0.05%-0.4% of Cr, 0.03%-0.3% of Ta, 0.03%-0.3% of Nb, 0.03%-0.3% of Ni, 0.01%-0.12% of Ti, 0.03%-0.6% of Y, 0.03%-0.6% of Ce, 0.03%-0.6% of Er, 0.005%-0.05% of Sr and the balance of aluminum. The preparation method comprises the following steps: mixing and smelting an aluminum ingot, metal silicon, an aluminum-manganese intermediate alloy, an aluminum-chromium intermediate alloy, an aluminum-tantalum intermediate alloy, an aluminum-niobium intermediate alloy, an aluminum-nickel intermediate alloy, an aluminum-titanium intermediate alloy, an aluminum-yttrium intermediate alloy, an aluminum-cerium intermediate alloy and an aluminum-erbium intermediate alloy to obtain a melt I; adding a magnesium ingot into the melt I, smelting, introducing argon, refining to obtain molten aluminum, and casting to obtain an aluminum alloy ingot. The method is suitable for high-pressure casting forming to prepare force-bearing structural parts with complex shapes, can have good mechanical properties without heat treatment, and can be used for production of various parts required by new energy automobiles.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloys and processing thereof, and particularly relates to a heat-treatment-free die-casting aluminum alloy for structural parts and a method for preparing the die-casting parts. Background Art

[0002] With the continuous development of the new energy vehicle industry, under the premise of a certain battery capacity, only by further reducing the weight can the mileage of new energy vehicles be improved to meet the development of the industry and user needs. This has led to the application of high-performance aluminum alloy materials and high-pressure casting processes in new energy vehicles gradually gaining attention.

[0003] Traditional aluminum alloy materials, whether cast aluminum alloys or deformed aluminum alloys, require a series of heat treatment processes such as quenching and artificial aging to improve performance. The die-castings produced by the die-casting process have the characteristics of thin walls and complex shapes. After heat treatment, especially after quenching, the probability of deformation is very high, resulting in an increase in scrap rate. At the same time, traditional die-casting aluminum alloy materials such as ADC12, A380, 46500, etc. are all die-casting aluminum alloys of the Al-Si-Cu system. They have good strength without heat treatment, but their plasticity is low, which makes it difficult to meet the performance requirements of aluminum alloy die-castings in the new energy vehicle industry.

[0004] In order to improve the performance of die-cast aluminum alloys, researchers hope to obtain die-castings with excellent mechanical properties and plasticity by adding different alloy elements, such as heat-treatment-free die-casting aluminum alloys and preparation methods thereof with the addition of Si, Cu, Mn, Mg, Fe, V, Sr, Cr and other elements. However, the performance indicators of die-castings of heat-treatment-free die-casting aluminum alloy materials reported and applied at present still do not meet the development needs of lightweight new energy vehicles, and there is a problem of low strength. Summary of the invention

[0005] In view of the above-mentioned deficiencies, the present invention discloses a heat-treatment-free die-cast aluminum alloy for structural parts and a method for preparing die-cast parts. By rationally optimizing the alloying elements of the aluminum alloy and adding an appropriate amount of rare earth elements for micro-alloying, the strength of the alloy material die-cast parts is improved so that they have higher strength and plasticity without heat treatment, so as to meet the development needs of various application fields.

[0006] The present invention is achieved by adopting the following technical solutions: A heat treatment-free die-casting aluminum alloy for structural parts, comprising the following components in percentage by mass: 7.5-11.5% Si, Fe≤0.2%, 0.6-1.2% Mg, 0.05-0.8% Mn, 0.05-0.4% Cr, 0.03-0.3% Ta, 0.03-0.3% Nb, 0.03-0.3% Ni, 0.01-0.12% Ti, 0.03-0.6% Y, 0.03-0.6% Ce, 0.03-0.6% Er, 0.005-0.05% Sr, other unavoidable single impurity elements ≤0.03%, the total amount of impurity elements ≤0.15%, and the balance is aluminum.

[0007] Furthermore, the heat treatment-free die-casting aluminum alloy for structural parts comprises the following components in percentage by mass: 8~11.0% Si, Fe≤0.15%, 0.8~1.0% Mg, 0.2~0.6% Mn, 0.15~0.35% Cr, 0.08~0.28% Ta, 0.08~0.28% Nb, 0.08~0.28% Ni, 0.015~0.10% Ti, 0.1~0.5% Y, 0.1~0.5% Ce, 0.1~ 0.5% Er, 0.008-0.04% Sr, other unavoidable single impurity elements ≤0.03%, the total amount of impurity elements ≤0.15%, and the balance is aluminum; the total content of Ta and Nb is 0.2-0.48%; the total content of Y, Ce and Er is 0.35-1.3%, and the ratio of the three contents Y:Ce:Er is (1-4):(2-5):(1-4).

[0008] A method for preparing a heat-treatment-free die-cast aluminum alloy for structural parts, comprising the following steps: (1) According to the composition of the above-mentioned heat treatment-free die-casting aluminum alloy, aluminum ingot, metallic silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-tantalum master alloy, aluminum-niobium master alloy, aluminum-nickel master alloy, aluminum-titanium master alloy, aluminum-yttrium master alloy, aluminum-cerium master alloy and aluminum-erbium master alloy are selected and charged into a melting furnace, the temperature is raised to 740-820° C., and then the melt is kept at this temperature for 1-2 hours to obtain melt I; (2) adding a magnesium ingot to the melt I obtained in step (1), and when the magnesium ingot is completely melted, smelting at 700 to 740° C. for 1 to 2 hours to obtain a melt II; (3) Sampling the melt II obtained in step (2) to test the composition. If the composition is unqualified, adjusting and adding the corresponding intermediate aluminum alloy according to the result until the composition is qualified; after the composition is qualified, refining the melt II, i.e., introducing argon gas into the melt II and refining it at 680-720° C., letting it stand after refining and removing the slag on the surface to obtain aluminum liquid; (4) The aluminum liquid obtained in step (3) is discharged from the smelting furnace, and after double-stage filtration, it is sent into an automatic casting machine for casting to obtain an aluminum alloy ingot. During the casting, the temperature of the aluminum liquid is maintained at 640-720° C., and the tensile strength of the aluminum alloy ingot is ≥190 MPa.

[0009] Furthermore, in step (3), the refining time is 15 to 30 minutes, and the argon gas is 99.99% high-purity argon gas.

[0010] Furthermore, in step (4), the double-stage filtration is to first use a 60-mesh filter plate for the first stage filtration, and then use an 80-mesh filter plate for the second stage filtration.

[0011] The application of the heat-treatment-free die-cast aluminum alloy for structural parts in die-cast products comprises the following steps: S1, placing the aluminum alloy ingot obtained by the casting into a melting furnace, heating and remelting to obtain melt III; S2, introducing argon gas into the melt III obtained in step S1, refining and slagging, and then standing for 15 to 30 minutes; S3, after cooling down the melt III treated in step S2, taking the melt III and transferring it to a cold chamber die casting machine for high pressure casting, and after cooling, obtaining an aluminum alloy die casting having high strength and toughness and no heat treatment required.

[0012] Further, in step S1, the remelting temperature is 650-750°C; Furthermore, in step S2, the refining temperature is 700-740°C, the refining time is 15-30 minutes, and the argon gas is 99.99% high-purity argon gas.

[0013] Furthermore, in step S3, during the high-pressure casting process, the first-stage injection speed is 0.1-0.3 m / s, the second-stage injection speed is 3-6 m / s, the third-stage injection speed is 15-25 m / s, the die-casting pressure is 60-140 MPa, and the holding time is 30-60 seconds.

[0014] Compared with the prior art, this technical solution has the following beneficial effects: 1. The present invention improves the mechanical properties of aluminum alloy die-castings by adding appropriate amounts of rare earth elements Y, Ce and Er to Al-Si-Mg series die-cast aluminum alloys. The rare earth elements Y, Ce and Er have two functions: on the one hand, Y, Ce and Er can effectively purify and remove hydrogen elements and inclusions in the aluminum liquid during the smelting process to ensure the cleanliness of the aluminum liquid; on the other hand, Y, Ce and Er can effectively refine the grain size of the cast aluminum alloy during the casting process to obtain a fine grain structure.

[0015] 2. The present invention improves the comprehensive performance of aluminum alloy die castings by adding appropriate amounts of transition metal elements Mn, Cr, Ta, Nb, Ni, and Ti to the Al-Si-Mg series die-cast aluminum alloy. The transition metal elements have the following main functions: first, the function of Mn and Cr elements is to improve the die sticking tendency of the die-cast aluminum alloy, and at the same time, they form intermetallic compounds with Si and Fe elements to improve the strength of the alloy; second, Ta and Nb elements can interact with rare earth elements to generate complex intermetallic compounds, resulting in better grain refinement; third, Ni and Ti elements play a role in grain refinement.

[0016] 3. The present invention adds an appropriate amount of Sr element, combined with rare earth elements Y, Ce, and Er, which can produce a good modification effect on the Si phase in the alloy, refine the Si phase, and improve the plasticity of the die casting. DETAILED DESCRIPTION

[0017] The present invention is further described by the following examples, but is not intended to be limiting of the present invention. Specific experimental conditions and methods not specified in the following examples are conventional methods commonly known to those skilled in the art.

[0018] Embodiment 1: A heat-treatment-free die-cast aluminum alloy for structural parts, comprising the following components in mass percentage: Si: 9.6%, Fe: 0.12%, Mg: 0.88%, Mn: 0.45%, Cr: 0.20%, Ta: 0.16%, Nb: 0.14%, Ni: 0.17%, Ti: 0.06%, Y: 0.21%, Ce: 0.26%, Er: 0.27%, Sr: 0.02%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, and the balance is aluminum; the total content of Ta and Nb is 0.30%; the total content of Y, Ce and Er is 0.74%, and the content ratio of the three, Y:Ce:Er, is 2.1:2.6:2.7.

[0019] The method for preparing the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment comprises the following steps: (1) According to the composition of the heat treatment-free die-casting aluminum alloy, aluminum ingots, metallic silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-tantalum master alloy, aluminum-niobium master alloy, aluminum-nickel master alloy, aluminum-titanium master alloy, aluminum-yttrium master alloy, aluminum-cerium master alloy and aluminum-erbium master alloy are selected and loaded into a melting furnace, the temperature is raised to 780° C., and then the melt is kept at this temperature for 1.5 hours to obtain melt I; (2) adding a magnesium ingot to the melt I obtained in step (1), and when the magnesium ingot is completely melted, smelting at 730° C. for 1.5 hours to obtain a melt II; (3) Sampling the melt II obtained in step (2) to detect the composition. If the composition is unqualified, adjusting and adding the corresponding intermediate aluminum alloy according to the result until the composition is qualified; after the composition is qualified, refining the melt II, that is, introducing argon gas into the melt II and refining treatment at 715° C., the refining time is 25 minutes, the argon gas is 99.99% high-purity argon gas, and after refining, the melt II is allowed to stand and the slag on the surface is removed to obtain aluminum liquid; (4) The aluminum liquid obtained in step (3) is discharged from the smelting furnace, and after double-stage filtration, it is cast in an automatic casting machine to obtain an aluminum alloy ingot, and the aluminum liquid temperature is maintained at 705°C during casting; the double-stage filtration is firstly performed by using a 60-mesh filter plate for the first stage filtration, and then a 80-mesh filter plate for the second stage filtration; the tensile strength of the obtained aluminum alloy ingot is tested, and the aluminum alloy ingot with a tensile strength ≥190 MPa is selected for use.

[0020] The application of the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment in die-cast products comprises the following steps: S1, placing the cast aluminum alloy ingot into a melting furnace, heating it to 710° C., and remelting it to obtain melt III; S2, introducing argon gas into the melt III obtained in step S1 and performing refining and slagging treatment, and then standing for 20 minutes; the refining temperature is 705° C., the refining time is 30 minutes, and the argon gas is 99.99% high-purity argon gas; S3. After cooling the melt III treated in step S2, the melt III is transferred to a cold chamber die-casting machine for high-pressure casting, and after cooling, an aluminum alloy die-casting having high strength and toughness and no heat treatment performance is obtained; during the high-pressure casting process, the first-stage injection speed is 0.2 m / s, the second-stage injection speed is 4.5 m / s, the third-stage injection speed is 18 m / s, the die-casting pressure is 100 MPa, and the holding time is 45 seconds.

[0021] Embodiment 2: A heat treatment-free die-casting aluminum alloy for structural parts, comprising the following components in percentage by mass: Si: 8.8%, Fe: 0.10%, Mg: 0.9%, Mn: 0.45%, Cr: 0.31%, Ta: 0.20%, Nb: 0.22%, Ni: 0.13%, Ti: 0.08%, Y: 0.3%, Ce: 0.45%, Er: 0.32%, Sr: 0.01%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, the balance is aluminum; the total content of Ta and Nb is 0.42%; the total content of Y, Ce and Er is 1.17%, and the content ratio of the three, Y:Ce:Er, is 3:4.5:3.2.

[0022] The method for preparing the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment comprises the following steps: (1) According to the composition of the heat treatment-free die-casting aluminum alloy, aluminum ingots, metallic silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-tantalum master alloy, aluminum-niobium master alloy, aluminum-nickel master alloy, aluminum-titanium master alloy, aluminum-yttrium master alloy, aluminum-cerium master alloy and aluminum-erbium master alloy are selected and loaded into a melting furnace, the temperature is raised to 770° C., and then the melt is kept at this temperature for 1.5 hours to obtain melt I; (2) adding a magnesium ingot to the melt I obtained in step (1), and when the magnesium ingot is completely melted, smelting at 725° C. for 1.5 hours to obtain a melt II; (3) Sampling the melt II obtained in step (2) to detect the composition. If the composition is unqualified, adjusting and adding the corresponding intermediate aluminum alloy according to the result until the composition is qualified; after the composition is qualified, refining the melt II, that is, introducing argon gas into the melt II and refining treatment at 715° C., the refining time is 25 minutes, the argon gas is 99.99% high-purity argon gas, and after refining, the melt II is allowed to stand and the slag on the surface is removed to obtain aluminum liquid; (4) The aluminum liquid obtained in step (3) is discharged from the smelting furnace, and after double-stage filtration, it is cast in an automatic casting machine to obtain an aluminum alloy ingot, and the aluminum liquid temperature is maintained at 705°C during casting; the double-stage filtration is firstly performed by using a 60-mesh filter plate for the first stage filtration, and then a 80-mesh filter plate for the second stage filtration; the tensile strength of the obtained aluminum alloy ingot is tested, and the aluminum alloy ingot with a tensile strength ≥190 MPa is selected for use.

[0023] The application of the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment in die-cast products comprises the following steps: S1, placing the cast aluminum alloy ingot into a melting furnace, heating it to 710° C., and remelting it to obtain melt III; S2, introducing argon gas into the melt III obtained in step S1 and performing refining and slagging treatment, and then standing for 25 minutes; the refining temperature is 705° C., the refining time is 30 minutes, and the argon gas is 99.99% high-purity argon gas; S3. After cooling the melt III treated in step S2, the melt III is transferred to a cold chamber die-casting machine for high-pressure casting, and after cooling, an aluminum alloy die-casting having high strength and toughness and no heat treatment performance is obtained; during the high-pressure casting process, the first-stage injection speed is 0.2 m / s, the second-stage injection speed is 4.5 m / s, the third-stage injection speed is 18 m / s, the die-casting pressure is 100 MPa, and the holding time is 45 seconds.

[0024] Embodiment 3: A heat-treatment-free die-cast aluminum alloy for structural parts, comprising the following components in mass percentage: Si: 9.2%, Fe: 0.10%, Mg: 0.85%, Mn: 0.48%, Cr: 0.20%, Ta: 0.15%, Nb: 0.18%, Ni: 0.17%, Ti: 0.07%, Y: 0.1%, Ce: 0.5%, Er: 0.35%, Sr: 0.02%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, and the balance is aluminum; the total content of Ta and Nb is 0.23%; the total content of Y, Ce and Er is 0.95%, and the content ratio of the three, Y:Ce:Er, is 1:5:3.5.

[0025] The method for preparing the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment comprises the following steps: (1) According to the composition of the heat treatment-free die-casting aluminum alloy, aluminum ingots, metallic silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-tantalum master alloy, aluminum-niobium master alloy, aluminum-nickel master alloy, aluminum-titanium master alloy, aluminum-yttrium master alloy, aluminum-cerium master alloy and aluminum-erbium master alloy are selected and loaded into a melting furnace, the temperature is raised to 780° C., and then the melt is kept at this temperature for 1.5 hours to obtain melt I; (2) adding a magnesium ingot to the melt I obtained in step (1), and when the magnesium ingot is completely melted, smelting at 730° C. for 1.5 hours to obtain a melt II; (3) Sampling the melt II obtained in step (2) to detect the composition. If the composition is unqualified, adjusting and adding the corresponding intermediate aluminum alloy according to the result until the composition is qualified; after the composition is qualified, refining the melt II, that is, introducing argon gas into the melt II and refining treatment at 712° C., the refining time is 25 minutes, the argon gas is 99.99% high-purity argon gas, and after refining, the melt II is allowed to stand and the slag on the surface is removed to obtain aluminum liquid; (4) The aluminum liquid obtained in step (3) is discharged from the smelting furnace, and after double-stage filtration, it is sent into an automatic casting machine for casting to obtain an aluminum alloy ingot, and the aluminum liquid temperature is maintained at 708°C during casting; the double-stage filtration is firstly performed by using a 60-mesh filter plate for the first stage filtration, and then a 80-mesh filter plate for the second stage filtration; the tensile strength of the obtained aluminum alloy ingot is tested, and the aluminum alloy ingot with a tensile strength ≥190 MPa is selected for use.

[0026] The application of the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment in die-cast products comprises the following steps: S1, placing the cast aluminum alloy ingot into a melting furnace, heating it to 710° C., and remelting it to obtain melt III; S2, introducing argon gas into the melt III obtained in step S1 and performing refining and slagging treatment, and then standing for 20 minutes; the refining temperature is 705° C., the refining time is 30 minutes, and the argon gas is 99.99% high-purity argon gas; S3. After cooling the melt III treated in step S2, the melt III is transferred to a cold chamber die-casting machine for high-pressure casting, and after cooling, an aluminum alloy die-casting having high strength and toughness and no heat treatment performance is obtained; during the high-pressure casting process, the first-stage injection speed is 0.2 m / s, the second-stage injection speed is 4.5 m / s, the third-stage injection speed is 18 m / s, the die-casting pressure is 100 MPa, and the holding time is 45 seconds.

[0027] Embodiment 4: A heat treatment-free die-casting aluminum alloy for structural parts, comprising the following components in percentage by mass: Si: 8.9%, Fe: 0.13%, Mg: 0.96%, Mn: 0.52%, Cr: 0.33%, Ta: 0.24%, Nb: 0.26%, Ni: 0.13%, Ti: 0.08%, Y: 0.45%, Ce: 0.5%, Er: 0.08%, Sr: 0.01%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, the balance is aluminum; the total content of Ta and Nb is 0.50%; the total content of Y, Ce and Er is 1.03%, and the content ratio of the three, Y:Ce:Er, is 4.5:5:0.8.

[0028] The method for preparing the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment comprises the following steps: (1) According to the composition of the heat treatment-free die-casting aluminum alloy, aluminum ingots, metallic silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-tantalum master alloy, aluminum-niobium master alloy, aluminum-nickel master alloy, aluminum-titanium master alloy, aluminum-yttrium master alloy, aluminum-cerium master alloy and aluminum-erbium master alloy are selected and loaded into a melting furnace, the temperature is raised to 760° C., and then the melt is kept at this temperature for 1.5 hours to obtain melt I; (2) adding a magnesium ingot to the melt I obtained in step (1), and when the magnesium ingot is completely melted, smelting at 725° C. for 1.5 hours to obtain a melt II; (3) Sampling the melt II obtained in step (2) to detect the composition. If the composition is unqualified, adjusting and adding the corresponding intermediate aluminum alloy according to the result until the composition is qualified; after the composition is qualified, refining the melt II, that is, introducing argon gas into the melt II and refining treatment at 710° C., the refining time is 25 minutes, the argon gas is 99.99% high-purity argon gas, and after refining, the melt II is allowed to stand and the slag on the surface is removed to obtain aluminum liquid; (4) The aluminum liquid obtained in step (3) is discharged from the smelting furnace, and after double-stage filtration, it is cast in an automatic casting machine to obtain an aluminum alloy ingot, and the aluminum liquid temperature is maintained at 705°C during casting; the double-stage filtration is firstly performed by using a 60-mesh filter plate for the first stage filtration, and then a 80-mesh filter plate for the second stage filtration; the tensile strength of the obtained aluminum alloy ingot is tested, and the aluminum alloy ingot with a tensile strength ≥190 MPa is selected for use.

[0029] The application of the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment in die-cast products comprises the following steps: S1, placing the cast aluminum alloy ingot into a melting furnace, heating it to 710° C., and remelting it to obtain melt III; S2, introducing argon gas into the melt III obtained in step S1 and performing refining and slagging treatment, and then standing for 25 minutes; the refining temperature is 705° C., the refining time is 30 minutes, and the argon gas is 99.99% high-purity argon gas; S3. After cooling the melt III treated in step S2, the melt III is transferred to a cold chamber die-casting machine for high-pressure casting, and after cooling, an aluminum alloy die-casting having high strength and toughness and no heat treatment performance is obtained; during the high-pressure casting process, the first-stage injection speed is 0.2 m / s, the second-stage injection speed is 4.5 m / s, the third-stage injection speed is 18 m / s, the die-casting pressure is 100 MPa, and the holding time is 45 seconds.

[0030] Embodiment 5: A heat-treatment-free die-cast aluminum alloy for structural parts, comprising the following components in mass percentage: Si: 7.5%, Fe: 0.2%, Mg: 0.6%, Mn: 0.05%, Cr: 0.05%, Ta: 0.03%, Nb: 0.03%, Ni: 0.03%, Ti: 0.01%, Y: 0.03%, Ce: 0.03%, Er: 0.03%, Sr: 0.005%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, and the balance is aluminum; the total content of Ta and Nb is 0.06%; the total content of Y, Ce and Er is 0.06%, and the content ratio of the three, Y:Ce:Er, is 1:1:1.

[0031] The method for preparing the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment comprises the following steps: (1) According to the composition of the heat treatment-free die-casting aluminum alloy, aluminum ingots, metallic silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-tantalum master alloy, aluminum-niobium master alloy, aluminum-nickel master alloy, aluminum-titanium master alloy, aluminum-yttrium master alloy, aluminum-cerium master alloy and aluminum-erbium master alloy are selected and loaded into a melting furnace, the temperature is raised to 740° C., and then the melt is kept at this temperature for 1 hour to obtain melt I; (2) adding a magnesium ingot to the melt I obtained in step (1), and when the magnesium ingot is completely melted, smelting at 700° C. for 1 hour to obtain a melt II; (3) Sampling the melt II obtained in step (2) to detect the composition. If the composition is unqualified, adjusting and adding the corresponding intermediate aluminum alloy according to the result until the composition is qualified; after the composition is qualified, refining the melt II, that is, introducing argon gas into the melt II and refining treatment at 680° C., the refining time is 30 minutes, the argon gas is 99.99% high-purity argon gas, and after refining, the melt II is allowed to stand and the slag on the surface is removed to obtain aluminum liquid; (4) The aluminum liquid obtained in step (3) is discharged from the smelting furnace, and after double-stage filtration, it is sent into an automatic casting machine for casting to obtain an aluminum alloy ingot, and the aluminum liquid temperature is maintained at 640°C during casting; the double-stage filtration is firstly performed by using a 60-mesh filter plate for the first stage filtration, and then a 80-mesh filter plate for the second stage filtration; the tensile strength of the obtained aluminum alloy ingot is tested, and the aluminum alloy ingot with a tensile strength ≥190 MPa is selected for use.

[0032] The application of the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment in die-cast products comprises the following steps: S1, placing the cast aluminum alloy ingot into a melting furnace, heating it to 650° C., and remelting it to obtain melt III; S2, introducing argon gas into the melt III obtained in step S1 and performing refining and slagging treatment, and then standing for 30 minutes; the refining temperature is 700° C., the refining time is 30 minutes, and the argon gas is 99.99% high-purity argon gas; S3. After cooling the melt III treated in step S2, transfer the melt III to a cold chamber die-casting machine for high-pressure casting, and obtain an aluminum alloy die-casting with high strength and toughness and no heat treatment performance after cooling; in the high-pressure casting process, the first-stage injection speed is 0.1m / s, the second-stage injection speed is 3m / s, the third-stage injection speed is 15m / s, the die-casting pressure is 60MPa, and the holding time is 30 seconds.

[0033] Embodiment 6: A heat-treatment-free die-cast aluminum alloy for structural parts, comprising the following components in mass percentage: Si: 11.5%, Fe: 0.10%, Mg: 1.2%, Mn: 0.8%, Cr: 0.4%, Ta: 0.3%, Nb: 0.3%, Ni: 0.3%, Ti: 0.12%, Y: 0.6%, Ce: 0.6%, Er: 0.6%, Sr: 0.05%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, and the balance is aluminum; the total content of Ta and Nb is 0.6%; the total content of Y, Ce and Er is 1.8%, and the content ratio of the three, Y:Ce:Er, is 1:1:1.

[0034] The method for preparing the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment comprises the following steps: (1) According to the composition of the heat treatment-free die-casting aluminum alloy, aluminum ingots, metallic silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-tantalum master alloy, aluminum-niobium master alloy, aluminum-nickel master alloy, aluminum-titanium master alloy, aluminum-yttrium master alloy, aluminum-cerium master alloy and aluminum-erbium master alloy are selected and loaded into a melting furnace, the temperature is raised to 820° C., and then the melt is kept at this temperature for 2 hours to obtain melt I; (2) adding a magnesium ingot to the melt I obtained in step (1), and when the magnesium ingot is completely melted, smelting at 740° C. for 2 hours to obtain a melt II; (3) Sampling the melt II obtained in step (2) to detect the composition. If the composition is unqualified, adjusting and adding the corresponding intermediate aluminum alloy according to the result until the composition is qualified; after the composition is qualified, refining the melt II, that is, introducing argon gas into the melt II and refining treatment at 720° C., the refining time is 15 minutes, the argon gas is 99.99% high-purity argon gas, and after refining, the melt II is allowed to stand and the slag on the surface is removed to obtain aluminum liquid; (4) The aluminum liquid obtained in step (3) is discharged from the smelting furnace, and after double-stage filtration, it is cast in an automatic casting machine to obtain an aluminum alloy ingot, and the aluminum liquid temperature is maintained at 720°C during casting; the double-stage filtration is firstly performed by using a 60-mesh filter plate for the first stage filtration, and then a 80-mesh filter plate for the second stage filtration; the tensile strength of the obtained aluminum alloy ingot is tested, and the aluminum alloy ingot with a tensile strength ≥190 MPa is selected for use.

[0035] The application of the heat-treatment-free die-cast aluminum alloy for structural parts described in this embodiment in die-cast products comprises the following steps: S1, placing the cast aluminum alloy ingot into a melting furnace, heating it to 750° C. for remelting to obtain melt III; S2, introducing argon gas into the melt III obtained in step S1 and performing refining and slagging treatment, and then standing for 15 minutes; the refining temperature is 740° C., the refining time is 15 minutes, and the argon gas is 99.99% high-purity argon gas; S3. After cooling the melt III treated in step S2, transfer the melt III to a cold chamber die-casting machine for high-pressure casting, and obtain an aluminum alloy die-casting with high strength and toughness and no heat treatment performance after cooling; in the high-pressure casting process, the first-stage injection speed is 0.3m / s, the second-stage injection speed is 6m / s, the third-stage injection speed is 25m / s, the die-casting pressure is 140MPa, and the holding time is 60 seconds.

[0036] Comparative Example 1: A die casting produced by conventional ADC12 alloy was used for comparison, wherein the mass percentage of the components of the ADC12 alloy is: Si: 11.2%, Mg: 0.19%, Cu: 2.0%, Mn: 0.42%, Zn: 0.66%, Ti: 0.13%, Fe: 0.87%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, and the balance is aluminum; An aluminum alloy die-casting is prepared according to the contents described in steps S1 to S3 in Example 1, wherein the die-casting temperature of the ADC12 alloy is 670°C, the first-stage injection speed during the die-casting process is 0.4 m / s, the second-stage injection speed is 4.5 m / s, the third-stage injection speed is 15.0 m / s, the die-casting pressure is 80 MPa, and the aluminum alloy die-casting is obtained after cooling.

[0037] Experimental Example: Aluminum alloy die castings were prepared according to the methods described in Examples 1 to 4 and Comparative Example 1, and then subjected to room temperature mechanical tests. The specific results are shown in Table 1.

[0038] Table 1 Performance test results of aluminum alloy die castings prepared by different methods

[0039] It can be seen from Table 1 that the mechanical properties and plasticity of the die castings prepared by the method of the present invention are better than those of the aluminum alloy die castings prepared using ADC12 alloy (Comparative Example 1), and have excellent performance.

[0040] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A heat-treatment-free die-casting aluminum alloy for structural parts, characterized in that: The following components are included in mass percentage: 7.5-11.5% Si, Fe≤0.2%, 0.6-1.2% Mg, 0.05-0.8% Mn, 0.05-0.4% Cr, 0.03-0.3% Ta, 0.03-0.3% Nb, 0.03-0.3% Ni, 0.01-0.12% Ti, 0.03-0.6% Y, 0.03-0.6% Ce, 0.03-0.6% Er, 0.005-0.05% Sr, other unavoidable single impurity elements ≤0.03%, the total amount of impurity elements ≤0.15%, and the balance is aluminum.

2. The heat-treatment-free die-casting aluminum alloy for structural parts according to claim 1, characterized in that: The heat-treatment-free die-casting aluminum alloy for structural parts comprises the following components in percentage by mass: 8~11.0% Si, Fe≤0.15%, 0.8~1.0% Mg, 0.2~0.6% Mn, 0.15~0.35% Cr, 0.08~0.28% Ta, 0.08~0.28% Nb, 0.08~0.28% Ni, 0.015~0.10% Ti, 0.1~0.5% Y, 0.1~0.5% Ce, 0.1 ~0.5% Er, 0.008~0.04% Sr, other unavoidable single impurity elements ≤0.03%, the total amount of impurity elements ≤0.15%, and the balance is aluminum; the total content of Ta and Nb is 0.2~0.48%; the total content of Y, Ce and Er is 0.35~1.3%, and the content ratio of the three is Y:Ce:Er (1~4):(2~5):(1~4).

3. A method for preparing a heat-treatment-free die-casting aluminum alloy for structural parts as claimed in claim 1 or 2, characterized in that: The following steps are involved: (1) According to the composition of the heat treatment-free die-casting aluminum alloy, aluminum ingots, metallic silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-tantalum master alloy, aluminum-niobium master alloy, aluminum-nickel master alloy, aluminum-titanium master alloy, aluminum-yttrium master alloy, aluminum-cerium master alloy and aluminum-erbium master alloy are selected and loaded into a melting furnace, heated to 740-820° C., and then kept warm for 1-2 hours to obtain melt I; (2) adding a magnesium ingot to the melt I obtained in step (1), and when the magnesium ingot is completely melted, smelting at 700 to 740° C. for 1 to 2 hours to obtain a melt II; (3) Sampling the melt II obtained in step (2) to test the composition. If the composition is unqualified, adjusting and adding the corresponding intermediate aluminum alloy according to the result until the composition is qualified; after the composition is qualified, refining the melt II, i.e., introducing argon gas into the melt II and refining it at 680-720° C., letting it stand after refining and removing the slag on the surface to obtain aluminum liquid; (4) The aluminum liquid obtained in step (3) is discharged from the smelting furnace, and after double-stage filtration, it is sent into an automatic casting machine for casting to obtain an aluminum alloy ingot. During the casting, the temperature of the aluminum liquid is maintained at 640-720° C., and the tensile strength of the aluminum alloy ingot is ≥190 MPa.

4. The preparation method according to claim 3, characterized in that: In step (3), the refining time is 15 to 30 minutes, and the argon gas is 99.99% high-purity argon gas.

5. The preparation method according to claim 3, characterized in that: In step (4), the double-stage filtration is to first use a 60-mesh filter plate for the first stage filtration, and then use an 80-mesh filter plate for the second stage filtration.

6. Application of the heat-treatment-free die-cast aluminum alloy for structural parts as claimed in claim 1 or 2 in die-cast products, characterized in that: The following steps are involved: S1, placing the ingot of the heat treatment-free die-casting aluminum alloy into a melting furnace, heating and remelting to obtain melt III; S2, introducing argon gas into the melt III obtained in step S1, refining and slagging, and then standing for 15 to 30 minutes; S3, after cooling down the melt III treated in step S2, taking the melt III and transferring it to a cold chamber die casting machine for high pressure casting, and after cooling, obtaining an aluminum alloy die casting having high strength and toughness and no heat treatment required.

7. The use according to claim 6, characterized in that: In step S1, the remelting temperature is 650-750°C.

8. The use according to claim 6, characterized in that: In step S2, the refining temperature is 700-740°C, the refining time is 15-30 minutes, and the argon gas is 99.99% high-purity argon gas.

9. The use according to claim 6, characterized in that: In step S3, during the high pressure casting process, the first stage injection speed is 0.1-0.3 m / s, the second stage injection speed is 3-6 m / s, the third stage injection speed is 15-25 m / s, the die casting pressure is 60-140 MPa, and the holding time is 30-60 seconds.

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