High-strength heat-resistant aluminum alloy and preparation method and application thereof

Abstract

The invention belongs to the technical field of aluminum alloys, and particularly relates to a high-strength heat-resistant aluminum alloy and a preparation method and application thereof. The aluminum alloy is prepared from, by weight, 5.2%-5.6% of Cu, 0.1%-0.3% of Zr, 0.7%-0.9% of Mg, 0.2%-0.4% of Zn, 0.3%-0.7% of rare earth elements and the balance Al and inevitable impurity elements. According to the Al-Cu-Zr-Mg-Zn-rare earth element system alloy, the alloy elements and the proportion are optimized, and in the Al-Cu-Zr-Mg-Zn-rare earth element system alloy, all the elements cooperate with one another, so that the aluminum alloy has excellent strength and heat resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloys, and more specifically, relates to a high-strength and heat-resistant aluminum alloy and a preparation method and application thereof. Background Art

[0002] Aluminum alloys have the advantages of high specific strength, corrosion resistance, low cost, easy processing and easy recycling, and they play an important role in industrial production, especially in the fields of aerospace and automobile manufacturing as important structural materials. With the rapid development of equipment manufacturing and the continuous expansion of application fields, the working environment faced by aluminum alloy materials has become more stringent, especially with higher requirements for their heat resistance.

[0003] Among aluminum alloys, the alloys with good heat resistance in Al-Cu casting alloys, such as ZL205A, ZL210A and A201.0 alloys, have tensile strengths of 240, 250 and 195 MPa at 250°C, and 175, 170 and 145 MPa at 300°C. In recent years, with the development of advanced equipment in China, many industries need casting aluminum alloy materials with higher heat resistance, requiring the tensile strength at 300°C to be no less than 200 MPa.

[0004] Numerous studies have shown that adding other alloying elements to form microalloying is an effective solution to improve the mechanical properties and thermal stability of aluminum alloys. Among them, the main function of adding Zr elements is to refine the grains and increase the recrystallization resistance of the alloy, thereby improving the creep resistance and thermal stability of the alloy at high temperatures. This is because aluminum alloys containing Zr elements will precipitate Al3Zr phases that are coherent with the matrix at grain boundaries or subgrain boundaries during homogenization treatment. Al3Zr has a strong inhibitory effect on dislocation and grain boundary movement, which can increase the recrystallization resistance of the alloy. Recrystallization in the subsequent heat treatment process will be suppressed, retaining the deformation structure of the alloy, reducing dislocation pile-up, weakening stress concentration, and thus improving the strength and toughness of the alloy. The layered structure retained by the aluminum alloy can deflect the expansion of cracks and lead to tortuous expansion of cracks, which is conducive to energy dissipation and makes the alloy have excellent ductility.

[0005] With the addition of Mg element, the number of Mg-Ag co-clusters formed in the early stage of aging increases, the nucleation position of Ω phase also increases accordingly, and then the volume fraction of Ω phase in the matrix also increases accordingly, making the Ω phase in the matrix fine and evenly dispersed, the aging response rate of the alloy is accelerated, the room temperature tensile strength is increased, and the tensile strength shows an increasing trend.

[0006] The Zn element has a very high solid solubility in the aluminum matrix. Due to the radius difference between Al atoms and Zn atoms, the alloy matrix produces a large lattice distortion, which can effectively reduce the stacking fault energy of the Al matrix and promote the precipitation of the strengthening phase, thereby improving the performance of the alloy.

[0007] The introduction of rare earth elements can be dissolved in the α-Al matrix, effectively make up for the surface defects of the alloy phase, reduce the surface tension between the Al-RE phase and the α-Al matrix, and thus increase the nucleation rate. At the same time, the rare earth elements will be adsorbed on the surface of the α-Al matrix, reducing its surface energy and the crystal nucleus growth rate, achieving the effect of fine grain strengthening; rare earth elements have strong dehydrogenation and deoxidation capabilities, and react chemically with H2 and O2 in the aluminum liquid. Moreover, rare earth elements will react with some elements of the aluminum alloy to form high melting point compounds. These compounds will serve as new nucleation sites and will also be pinned at the front of the aluminum liquid, hindering the migration of grain boundaries, reducing the grain growth rate, and achieving the purpose of strengthening.

[0008] CN118957367A discloses a 6000 series aluminum alloy material for automobile body panels and its high-efficiency and low-carbon preparation method. The aluminum alloy is composed of the following components: Ho 0.05-0.12wt.%, Mg 0.45-0.65wt.%, Si 0.85-1.10wt.%, Cu 0.05-0.20wt.%, the remainder is Al and unavoidable impurities, and the Mg / Si content ratio is 0.4-0.7. The preparation method of aluminum alloy thin plate comprises the following steps: (1) according to the aluminum alloy composition ratio, the aluminum alloy raw material is melted and cast to obtain a cast alloy ingot; (2) the ingot is directly hot-rolled and deformed without cooling after homogenization heat treatment, and then immediately coiled to obtain a hot-rolled strip coil, which is then cooled to room temperature and subjected to self-annealing treatment; (3) the hot-rolled strip coil is no longer subjected to intermediate annealing treatment, but directly cold-rolled and deformed to obtain a cold-rolled plate strip; (4) the plate strip is subjected to solid solution quenching and pre-aging treatment to obtain a T4P thin plate. The present invention forms a second phase with a suitable size, refines the grains, significantly improves the forming performance of the thin plate, and greatly shortens the preparation and processing procedures through reasonable preparation method optimization.

[0009] CN118932231A discloses a high-strength and damage-resistant 2xxx aluminum alloy, in particular, a high-strength and damage-resistant 2xxx aluminum alloy, its preparation method and application. The components of the aluminum alloy include: Cu: 4.5-5.5%, Mg: 0.5-1.2%, Mn: 0.2-0.5%, Ag: 0.65-1.2%, Fe<0.1%, Si<0.1%, Zr: 0.05-0.1%, and the balance is Al and inevitable impurities, each inevitable impurity is <0.05%, and the total impurities are <0.1%; wherein the weight ratio of Cu to Mg is 5-10. The present invention optimizes the ratio of the main microalloying elements, and in the Al-Cu-Mg-Ag-Mn-Zr system alloy provided, the elements cooperate with each other to form a strengthening phase dominated by the Ω phase, and the formation of this phase enables the alloy to have both high strength and high damage resistance.

[0010] CN117821812A discloses a high-strength heat-resistant hypoeutectic aluminum-silicon cast aluminum alloy and a preparation method thereof. The purpose of the present invention is to solve the problem that the room temperature mechanical properties of the hypoeutectic aluminum-silicon cast aluminum alloy are low and the thermal strength of the material is insufficient when the service temperature exceeds 200°C. The high-strength heat-resistant hypoeutectic aluminum-silicon cast aluminum alloy is composed of Si, Cu, Mg, Ag, Mn, Ti, V, Be, Ca, Sr, B and Al by mass fraction. The present invention is smelted, poured, subjected to three-stage solid solution treatment, quenched, pre-aging treatment, and aging treatment to obtain a high-strength heat-resistant hypoeutectic aluminum-silicon cast aluminum alloy, which has high tensile strength and yield strength and can work for a long time in an environment of 220°C without failure. The present invention is applied to the manufacturing field of cast aluminum alloys.

[0011] It can be seen from the above content that the strength and heat resistance of aluminum alloys can be improved by adding trace elements. The present invention provides a new aluminum alloy with excellent mechanical properties and heat resistance. Summary of the invention

[0012] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the prior art and provide a high-strength and heat-resistant aluminum alloy and its preparation method and application.

[0013] 5.2-5.6wt%, Zr 0.1-0.3wt%, Mg 0.7-0.9wt%, Zn 0.2-0.4wt%, rare earth elements 0.3-0.7wt%, the balance is Al and inevitable impurity elements. The present invention optimizes the alloy elements and the proportions, and in the provided Al-Cu-Zr-Mg-Zn-rare earth element system alloy, the elements cooperate with each other, so that the aluminum alloy has excellent strength and heat resistance.

[0014] The purpose of the present invention is to provide a high-strength and heat-resistant aluminum alloy.

[0015] Another object of the present invention is to provide a method for preparing a high-strength and heat-resistant aluminum alloy.

[0016] Another object of the present invention is to provide a high-strength and heat-resistant aluminum alloy for use in the automotive field.

[0017] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0018] A high-strength and heat-resistant aluminum alloy comprises, by weight: 5.2-5.6wt% Cu, 0.1-0.3wt% Zr, 0.7-0.9wt% Mg, 0.2-0.4wt% Zn, 0.3-0.7wt% rare earth elements, and the balance Al and unavoidable impurity elements.

[0019] In a preferred embodiment, the rare earth element is at least one of Sc, Sm, Nd and Yb; and the mass ratio of the at least one of Sc, Sm, Nd and Yb is 1:0.2-0.4:0.4-0.8.

[0020] In a further preferred embodiment, the rare earth elements are Sc, Sm, Nd and Yb, and the mass ratio of the sum of the masses of Sc, Sm and Nd and Yb is 1:0.2-0.4:0.4-0.8; and the mass ratio of Nd to Yb is 1:1-3.

[0021] Preferably, the aluminum alloy raw material is pure Al, Al-Cu master alloy, pure Mg, pure Zn, Al-Zr master alloy, Al-Sc master alloy, Al-Sm master alloy, Al-Nd master alloy and / or Al-Yb master alloy.

[0022] Preferably, the aluminum alloy raw material is pure Al, Al-Cu master alloy, pure Mg, pure Zn, Al-Zr master alloy, Al-Sc master alloy, Al-Sm master alloy, Al-Nd master alloy and / or Al-Yb master alloy.

[0023] Based on the above-mentioned method for preparing a high-strength and heat-resistant aluminum alloy, the preparation method comprises the following steps:

[0024] After the alloy components are prepared, the alloy is melted and cast in a vacuum induction melting furnace to obtain an alloy ingot;

[0025] The alloy ingot is subjected to homogenization treatment, solution treatment and aging treatment to obtain a high-strength heat-resistant aluminum alloy.

[0026] Preferably, the process of the solution treatment is: solution treatment at 520-540° C. for 2-4 hours and quenching in water to room temperature.

[0027] More preferably, the homogenization treatment is performed at 490-510° C. for 25-35 hours.

[0028] More preferably, the aging treatment is performed at 160-200° C. for 10-16 hours.

[0029] Based on the application of the high-strength and heat-resistant aluminum alloy described above in the automotive field.

[0030] The present invention has the following beneficial effects:

[0031] After a large number of experimental studies, the present invention optimizes the alloying elements and contents of aluminum alloy materials, so that the aluminum alloy has excellent mechanical properties and heat resistance. Specifically, appropriate amounts of Zr, Mg, Zn, and rare earth elements are added to the aluminum alloy, and the interaction between the elements is utilized to promote the improvement of the strength and heat resistance of the aluminum alloy, so that it has excellent application prospects in the field of automobile manufacturing. DETAILED DESCRIPTION

[0032] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0033] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0034] The preparation method of the aluminum alloy involved in the embodiment and the comparative example specifically comprises the following steps:

[0035] (1) According to the alloy composition, pure Al, Al-Cu master alloy, pure Mg, pure Zn, Al-Zr master alloy, Al-Sc master alloy, Al-Sm master alloy, Al-Nd master alloy and / or Al-Yb master alloy are prepared. Then the raw materials are placed in a vacuum induction melting furnace, evacuated and then helium is introduced, and then the raw materials are completely melted to obtain alloy melt, and the alloy melt is cast into an iron mold, ultrasonically treated at 160W for 10 minutes, and then cooled to room temperature, and the furnace is opened for sampling to obtain an ingot size of about Φ40mm×100mm.

[0036] (2) The alloy ingot is homogenized at 530°C for 30 hours, then air-cooled to room temperature, and the head and tail of the homogenized alloy are cut off by 4 mm each to ensure that there are no defects at both ends, and the surface of the alloy is smoothed with sandpaper. The alloy is then placed in a resistance furnace and heated to 460°C and kept warm for 2 hours, and then hot rolling is started, with the reduction amount for each pass controlled at about 2.5 mm; after each rolling pass, the alloy is returned to the resistance furnace and kept warm for 15 minutes; finally, the alloy is rolled to about 2.5 mm. The rolled alloy is solution treated at 530°C for 3 hours and quenched in water to room temperature, and then aged at 180°C for 12 hours to obtain a high-strength heat-resistant aluminum alloy.

[0037] The composition and content of the aluminum alloys involved in the embodiments and comparative examples are shown in Table 1:

[0038] Table 1

[0039]

[0040] Performance Testing

[0041] The properties of the aluminum alloys prepared in Examples 1-4 and Comparative Examples 1-7 were tested. The tensile strength and yield strength were tested at room temperature according to GB / T 228.1-2010; the tensile strength and yield strength were tested at high temperature according to GB / T 228.2-2015. The specific test results are shown in Table 2:

[0042] Table 2

[0043]

[0044] It can be seen from Table 1 that the aluminum alloy prepared by the present invention has excellent heat resistance and excellent mechanical properties. By comparing the embodiments with the comparative examples, it can be seen that the present invention optimizes the alloying elements and contents of the aluminum alloy material, so that the mechanical properties and heat resistance of the aluminum alloy are significantly improved, and it is also proved that the added elements have a synergistic effect, so that it has excellent application prospects in the field of automobile manufacturing.

[0045] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A high-strength and heat-resistant aluminum alloy, characterized in that: By weight: the aluminum alloy includes Cu 5.2-5.6wt%, Zr 0.1-0.3wt%, Mg 0.7-0.9wt%, Zn 0.2-0.4wt%, rare earth elements 0.3-0.7wt%, and the balance is Al and inevitable impurity elements.

2. The high-strength and heat-resistant aluminum alloy according to claim 1, characterized in that: The rare earth element is at least one of Sc, Sm, Nd and Yb; the mass ratio of the at least one of Sc, Sm, Nd and Yb is 1:0.2-0.4:0.4-0.

8.

3. A high-strength and heat-resistant aluminum alloy according to claim 1 or 2, characterized in that: The rare earth elements are Sc, Sm, Nd and Yb, the mass ratio of Sc, Sm to the sum of the masses of Nd and Yb is 1:0.2-0.4:0.4-0.8; the mass ratio of Nd to Yb is 1:1-3.

4. The high-strength and heat-resistant aluminum alloy according to claim 2, characterized in that: The aluminum alloy raw material is pure Al, Al-Cu master alloy, pure Mg, pure Zn, Al-Zr master alloy, Al-Sc master alloy, Al-Sm master alloy, Al-Nd master alloy and / or Al-Yb master alloy.

5. The high-strength and heat-resistant aluminum alloy according to claim 3, characterized in that: The aluminum alloy raw material is pure Al, Al-Cu master alloy, pure Mg, pure Zn, Al-Zr master alloy, Al-Sc master alloy, Al-Sm master alloy, Al-Nd master alloy and / or Al-Yb master alloy.

6. A method for preparing a high-strength and heat-resistant aluminum alloy according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: After the alloy components are prepared, the alloy is melted and cast in a vacuum induction melting furnace to obtain an alloy ingot; The alloy ingot is subjected to homogenization treatment, solution treatment and aging treatment to obtain a high-strength heat-resistant aluminum alloy.

7. The method for preparing a high-strength and heat-resistant aluminum alloy according to claim 6, characterized in that: The process of the solution treatment is: solution treatment at 520-540° C. for 2-4 hours and quenching in water to room temperature.

8. The method for preparing a high-strength and heat-resistant aluminum alloy according to claim 6 or 7, characterized in that: The homogenization treatment is carried out at 490-510° C. for 25-35 hours.

9. The method for preparing a high-strength and heat-resistant aluminum alloy according to claim 6 or 7, characterized in that: The aging treatment is performed at 160-200° C. for 10-16 hours.

10. Application of the high-strength and heat-resistant aluminum alloy according to any one of claims 1 to 5 in the automotive field.

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