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

Abstract

The application belongs to the technical field of aluminum alloy, and particularly relates to a high-strength heat-resistant aluminum alloy and a preparation method and application thereof. According to weight parts, the aluminum alloy comprises Cu 5.2-5.6 wt%, Zr 0.1-0.3 wt%, Mg 0.7-0.9 wt%, Zn 0.2-0.4 wt%, rare earth elements 0.3-0.7 wt%, and the balance of Al and inevitable impurity elements. The alloy elements and the proportioning are optimized, and in the Al-Cu-Zr-Mg-Zn-rare earth element system alloy provided by the application, the elements are mutually coordinated, so that the aluminum alloy has excellent strength and heat resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of aluminum alloy. More particularly, it relates to a high-strength heat-resistant aluminum alloy and a preparation method and application thereof. BACKGROUND

[0002] Aluminum alloy has high specific strength, corrosion resistance, low cost, easy processing and recycling, and other advantages, and occupies an important position in industrial production, especially in the fields of aerospace and automobile manufacturing as an important structural material. With the rapid development of equipment manufacturing and the continuous expansion of application fields, the working environment faced by aluminum alloy materials is more severe, especially the higher requirements for its heat resistance.

[0003] Among aluminum alloys, Al-Cu series cast alloys with good heat resistance such as ZL205A, ZL210A and A201.0 alloy have a tensile strength of 240, 250 and 195 MPa at 250℃, respectively, and a tensile strength of 175, 170 and 145 MPa at 300℃. In recent years, with the development of domestic advanced equipment, many industries need cast aluminum alloy materials with higher heat resistance, and the tensile strength at 300℃ is required to be not less than 200 MPa.

[0004] Numerous studies have shown that micro-alloying by adding other alloying elements is an effective solution to improve the mechanical properties and thermal stability of aluminum alloys. Among them, the main role of Zr element is to refine the grain and increase the recrystallization resistance of the alloy, thereby improving the creep resistance and thermal stability of the alloy at high temperature. This is because the aluminum alloy containing Zr element will precipitate Al3Zr phase at the grain boundary or subgrain boundary during homogenization treatment, which has a strong hindering effect on dislocation and grain boundary movement, can improve the recrystallization resistance of the alloy, and the subsequent recrystallization during heat treatment will be inhibited, the deformed structure of the alloy is retained, the dislocation pile-up is reduced, the stress concentration is weakened, and the strength and toughness of the alloy are improved. The retained lamellar structure of the aluminum alloy can deflect the crack propagation and cause the crack to propagate tortuously, which is beneficial to energy dissipation, so that the alloy has excellent ductility.

[0005] The addition of Mg element increases the number of Mg-Ag co-clusters formed at the initial aging stage, and the nucleation sites of Ω phase also increase, thereby increasing the volume fraction of Ω phase in the matrix, so that the Ω phase in the matrix is small and uniformly 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] Zn element has a high solid solubility in aluminum matrix. Due to the radius difference between Al atoms and Zn atoms, a large lattice distortion is generated in the alloy matrix, which can effectively reduce the stacking fault energy of the Al matrix, promote the precipitation of strengthening phases, and thus improve the performance of the alloy.

[0007] The introduction of rare earth elements can be dissolved in the a-Al matrix, effectively making up for the surface defects of the alloy phase, reducing the surface tension between the Al-RE phase and the a-Al matrix, thereby increasing the nucleation rate. At the same time, the rare earth elements will be adsorbed on the surface of the a-Al matrix, reducing the surface energy and the crystal nucleus growth rate, achieving the effect of fine-grain strengthening; the rare earth elements have strong dehydrogenation and deoxidation ability, and can react with H2 and O2 in the aluminum liquid. Moreover, the rare earth elements can react with some elements in the aluminum alloy to form high-melting-point compounds, which act as new nucleation sites and are pinned in the front of the aluminum liquid, hindering the migration of the grain boundary and reducing the grain growth rate, achieving the purpose of strengthening.

[0008] CN118957367A discloses a 6000 series aluminum alloy material for automobile body cover and a high-efficiency low-carbon preparation method thereof. The aluminum alloy is composed of Ho 0.05-0.12wt.%, Mg 0.45-0.65wt.%, Si 0.85-1.10wt.%, Cu 0.05-0.20wt.%, and the balance of Al and unavoidable impurities, with a Mg / Si content ratio of 0.4-0.7. The preparation method of the aluminum alloy sheet includes the following steps: (1) according to the component ratio of the aluminum alloy, the aluminum alloy raw material is melted and cast to obtain a cast alloy ingot; (2) the ingot is uniformly heat treated and then directly hot rolled without cooling 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 not subjected to intermediate annealing treatment and is directly cold-rolled to obtain a cold-rolled sheet; (4) the sheet is subjected to solid solution quenching and pre-aging treatment to obtain a T4P state sheet. The present application optimizes the preparation method to form second phases with appropriate sizes, refines the grains, significantly improves the forming performance of the sheet, and greatly shortens the preparation and processing procedures.

[0009] CN118932231A discloses a high-strength damage-resistant 2xxx series aluminum alloy, especially a high-strength damage-resistant 2xxx series aluminum alloy, a preparation method thereof and application. The composition of the aluminum alloy includes 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%, the balance being Al and unavoidable impurities, each unavoidable impurity <0.05%, and total impurities <0.1%; wherein the weight ratio of Cu to Mg is 5-10. The present application optimizes the ratio of main micro-alloying elements, and in the provided Al-Cu-Mg-Ag-Mn-Zr system alloy, each element cooperates with each other to form a strengthening phase mainly composed of Ω phase, which makes the alloy have high strength and high damage resistance.

[0010] CN117821812A discloses a high-strength heat-resistant hypoeutectic aluminum-silicon casting aluminum alloy and a preparation method thereof, and aims to solve the problems of low room temperature mechanical properties of hypoeutectic aluminum-silicon casting aluminum alloy and insufficient thermal strength of the material when the service temperature exceeds 200 DEG C. The high-strength heat-resistant hypoeutectic aluminum-silicon casting aluminum alloy is composed of Si, Cu, Mg, Ag, Mn, Ti, V, Be, Ca, Sr, B and Al according to mass fraction. The high-strength heat-resistant hypoeutectic aluminum-silicon casting aluminum alloy is obtained through melting, pouring, three-stage solid solution treatment, quenching, pre-aging treatment and aging treatment, and has high tensile strength and yield strength and can work long-term in an environment of 220 DEG C without failure. The application is applied to the manufacturing field of casting aluminum alloy.

[0011] From the above, it can be seen that the strength and heat resistance of the aluminum alloy can be improved by adding trace elements. The application provides a new type of aluminum alloy which has excellent mechanical properties and heat resistance. SUMMARY

[0012] The technical problem to be solved by the application is to overcome the defects and deficiencies of the prior art, and to provide a high-strength heat-resistant aluminum alloy, a preparation method and application thereof. According to weight parts, the aluminum alloy comprises Cu

[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%, and the balance of Al and inevitable impurity elements. The application optimizes the alloy elements and the ratio, and the Al-Cu-Zr-Mg-Zn-rare earth element system alloy provided by the application has excellent strength and heat resistance.

[0014] The application aims to provide a high-strength heat-resistant aluminum alloy.

[0015] Another object of the application is to provide a preparation method of the high-strength heat-resistant aluminum alloy.

[0016] Another object of the application is to provide an application of the high-strength heat-resistant aluminum alloy in the field of automobiles.

[0017] The above objects of the application are achieved by the following technical solutions.

[0018] A high-strength heat-resistant aluminum alloy, according to weight parts, comprises 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 of Al and inevitable impurity elements.

[0019] Preferably, the rare earth elements are Sc, Sm, at least one of Nd and Yb; the mass ratio of the at least one of Sc, Sm, at least one of Nd and Yb is 1:0.2-0.4:0.4-0.8.

[0020] Further preferably, the rare earth elements are Sc, Sm, Nd and Yb, the mass ratio of the sum of the mass of Sc, Sm and Nd and Yb is 1:0.2-0.4:0.4-0.8; the mass ratio of Nd and Yb is 1:1-3.

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

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

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

[0024] After the alloy components are proportioned, the alloy ingot is obtained by melting in a vacuum induction melting furnace and casting.

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

[0026] Preferably, the solid solution treatment process is: solid solution treatment at 520-540℃ for 2-4h and quenching in water to room temperature.

[0027] Further preferably, the homogenization treatment is at 490-510℃ for 25-35h.

[0028] More preferably, the aging treatment is at 160-200℃ for 10-16h.

[0029] Based on the above-mentioned high-strength heat-resistant aluminum alloy, the application in the field of automobiles.

[0030] The application has the following beneficial effects:

[0031] Through a large number of experimental researches, the alloy elements and contents of the aluminum alloy material are optimized, 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 in the aluminum alloy, the interaction between the elements is utilized, the strength and heat resistance of the aluminum alloy are promoted, and the aluminum alloy has excellent application prospect in the automobile manufacturing field. DETAILED DESCRIPTION

[0032] The application will be further described in conjunction with specific examples, but the examples do not limit the application in any form. Unless otherwise specified, the reagents, methods and equipment used in the application are conventional reagents, methods and equipment in the technical field.

[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 examples and comparative examples specifically includes the following steps:

[0035] (1) According to the alloy composition, prepare pure Al, Al-Cu intermediate alloy, pure Mg, pure Zn, Al-Zr intermediate alloy, Al-Sc intermediate alloy, Al-Sm intermediate alloy, Al-Nd intermediate alloy and / or Al-Yb intermediate alloy. Then place the raw materials in a vacuum induction melting furnace, vacuumize, then introduce helium, then completely melt the raw materials to obtain an alloy melt, pour the alloy melt into an iron mold, ultrasonic treat at 160W for 10min, then cool to room temperature, open the furnace and take samples to obtain a cast ingot with a size of about Φ40mmx100mm.

[0036] (2) The alloy ingot is subjected to homogenization treatment at 530℃ for 30h, then air-cooled to room temperature, cut off 4mm from the head and tail of the alloy after homogenization to ensure that the two ends are free of defects, and then grind the surface of the alloy with sandpaper. Then heat the alloy to 460℃ in a resistance furnace and keep it for 2 hours, then start hot rolling with a reduction of about 2.5mm per pass; after each pass, put the alloy back into the resistance furnace for 15 minutes; finally, roll the alloy to about 2.5mm. The rolled alloy is subjected to solid solution treatment at 530℃ for 3h and quenched in water to room temperature, and then aged at 180℃ for 12h to obtain a high-strength heat-resistant aluminum alloy.

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

[0038] Table 1

[0039]

[0040] Performance test

[0041] The properties of the aluminum alloys prepared in Examples 1-4 and Comparative Examples 1-7 were tested, and the test method was as follows: the tensile strength and yield strength were tested at room temperature according to the standard GB / T 228.1-2010; and 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] As can be seen from Table 1, the aluminum alloy prepared in the present application has excellent heat resistance and also has excellent mechanical properties. Through comparison of the examples and the comparative examples, it can be seen that, by optimizing the alloying elements and contents of the aluminum alloy material, the mechanical properties and heat resistance of the aluminum alloy are significantly improved, and it is also proved that the added elements have a mutual synergistic effect, so that it has excellent application prospect in the field of automobile manufacturing.

[0045] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and all are included in the protection scope of the present application.

Claims

1. A high-strength heat-resistant aluminum alloy, characterized by comprising: The aluminum alloy comprises 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 of Al and inevitable impurities by weight; The rare earth elements are Sc, Sm, Nd and Yb, and the mass ratio of the sum of the mass of Sc, Sm and Nd and Yb is 1:0.2-0.4:0.4-0.8; the mass ratio of Nd and Yb is 1:1-3.

2. The high-strength heat-resistant aluminum alloy according to claim 1, characterized by: The aluminum alloy raw material is pure Al, Al-Cu intermediate alloy, pure Mg, pure Zn, Al-Zr intermediate alloy, Al-Sc intermediate alloy, Al-Sm intermediate alloy, Al-Nd intermediate alloy and Al-Yb intermediate alloy.

3. The method for preparing a high-strength, heat-resistant aluminum alloy according to any one of claims 1-2, characterized in that: The preparation method comprises the following steps: after the alloy components are dosed, melting in a vacuum induction melting furnace, and casting to obtain an alloy ingot; the alloy ingot is subjected to homogenization treatment, solid solution treatment and aging treatment to obtain a high-strength heat-resistant aluminum alloy.

4. The method of claim 3, wherein the high-strength heat-resistant aluminum alloy is prepared by the following steps of: The solid solution treatment process is: solid solution at 520-540℃ for 2-4h and quenching in water to room temperature. ​ 5. A method for preparing a high-strength, heat-resistant aluminum alloy according to claim 3 or 4, characterized in that: The homogenization treatment is at 490-510℃ for 25-35h.

6. A method for preparing a high-strength, heat-resistant aluminum alloy according to claim 3 or 4, characterized in that: The aging treatment is at 160-200℃ for 10-16h.

7. Application of the high-strength heat-resistant aluminum alloy according to any one of claims 1-2 in the automobile field.

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