A high-strength conductive Al-Si-Mg-Zr-Er aluminum alloy and preparation method thereof

Abstract

The present application discloses a high-strength and high-conductivity Al‑Si‑Mg‑Zr‑Er aluminum alloy and a preparation method thereof. The method comprises the following steps: selecting aluminum ingots, magnesium ingots, Al‑20Si alloys, Al‑10Zr alloys, and Al‑10Er alloys as raw materials for smelting to form aluminum alloy melt; refining the aluminum alloy melt with a refining agent to perform impurity removal treatment in a furnace; casting the aluminum alloy melt to form an ingot plate, and further treating the ingot plate by a composite method of rolling and heat treatment. The method of the present invention can optimize the composition of aluminum alloy thermal conductive materials and prepare an aluminum alloy with excellent comprehensive mechanical properties and electrical conductivity.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy materials, and in particular to a high-strength conductive Al-Si-Mg-Zr-Er aluminum alloy and a preparation method thereof. Background Art

[0002] At present, due to the many advantages of aluminum alloys such as low density, high specific strength, low resistivity, high thermal conductivity, and easy forming, the research and application of aluminum alloys in the automotive industry and electric transportation have attracted much attention. The use of aluminum alloys can greatly reduce the weight of the car body, which is of great significance to the lightweight of the entire vehicle. In terms of electric transportation, taking the 6-series Al-Si-Mg alloy as an example, commercial 6000-series conductive aluminum alloys such as 6101 and 6201 aluminum alloys have been promoted and applied in fields such as power transmission. The 6-series aluminum alloy is based on Mg and Si as the main alloying elements, and Mg can be precipitated by aging. 2 Si strengthening phase belongs to heat-treatable strengthening aluminum alloy, and is also a medium-strength conductive aluminum alloy. However, the contradiction between the mechanical properties and conductive properties of aluminum alloy conductor materials has not been well resolved. Aluminum alloys cannot meet their performance requirements in some harsh use environments. Therefore, it is essential to reasonably control the composition of the alloy and optimize the processing technology.

[0003] The Chinese invention patent "A composite deformation heat treatment method for regulating the electrical conductivity and mechanical properties of aluminum alloys" with announcement number CN 115198213 B discloses a composite deformation heat treatment process. The invention is aimed at 6101 deformed aluminum alloy. First, the casting ingot is homogenized, and then hot-rolled to obtain a plate of a certain thickness. After cooling, it is cold-rolled at room temperature. The rolled deformed plate is quickly solid-solution quenched to obtain a saturated solid solution, and then intermediate pre-aging is performed. After being taken out of the furnace, multiple temperature-variable rolling is performed immediately (natural cooling during the rolling process, the cooling speed is first fast and then slow), and finally the final aging is performed. The electrical conductivity can reach 60% and the IACS yield strength range is 175~230MPa, which can achieve the simultaneous improvement of electrical conductivity and mechanical properties.

[0004] The above technology involves the thermomechanical treatment process of deformed aluminum alloys. Based on the thermomechanical treatment, the alloy phase structure can be regulated to ensure its excellent mechanical properties and electrical conductivity. However, for the automotive industry and other fields, the strength requirements are higher. The present invention aims to seek a high-strength and high-conductivity aluminum alloy to meet its requirements. Therefore, on the basis of the above-mentioned thermomechanical treatment process involving deformed aluminum alloys, the alloy composition is optimized and the process parameters are changed, so as to regulate the mechanical properties and electrical conductivity of the alloy. Summary of the invention

[0005] The purpose of the present invention is to provide a high-strength conductive Al-Si-Mg-Zr-Er aluminum alloy and a preparation method, so as to improve the mechanical properties and electrical conductivity of the Al-Mg-Si alloy and better meet the needs of the automotive industry and other fields for high-performance aluminum alloys.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] A high-strength and high-conductivity Al-Mg-Si-Zr-Er alloy comprises the following components in mass percentage: 0.65-0.8% Mg, 0.7-1% Si, 0.1-0.15% Zr, 0.10-0.3% Er, and the balance is Al and other inevitable impurities.

[0008] Technical principle of the present invention:

[0009] By adding trace amounts of transition metals and rare earth elements, the precipitation behavior of the alloy can be affected, thereby significantly improving the comprehensive properties of the aluminum alloy. Zr and Er are added to Al, and the Zr element forms Al 3 When Zr is dispersed and finely precipitated, it acts as a heterogeneous nucleation core, hindering the nucleation of recrystallization during heating, thereby refining the grains of the aluminum alloy. However, excessive Zr elements will have an adverse effect on the electrical conductivity of the alloy. Therefore, the addition amount of Zr elements is controlled. Er elements can increase the supercooling of the aluminum alloy components, refine the grains, reduce the gas and inclusions in the alloy, and improve the strength and conductivity of the aluminum alloy. At the same time, Er can form a finer and dispersed Al with Zr. 3 (Zr, Er) composite phase improves the strength and heat resistance of the alloy. Research has found that the composite addition of two or more micro-alloying elements can better play the role of micro-alloying elements and reduce the use of precious metal elements, thereby reducing costs.

[0010] By optimizing the types and contents of alloying elements and adopting scientific smelting, casting and deformation heat treatment processes, various alloys can be fully integrated into aluminum alloys and interact with each other. At the same time, the existence form of alloying elements and the organizational structure of aluminum alloys are controlled, so that aluminum alloys have excellent mechanical properties and good electrical conductivity, further improving the application of aluminum alloys in the automotive industry and electric power transportation fields.

[0011] The present invention also provides a method for preparing a high-strength and high-conductivity Al-Mg-Si-Zr-Er alloy, comprising the following steps:

[0012] Step 1: Prepare alloy ingot plate

[0013] (1) Ingredients: According to the mass percentage of alloy elements, aluminum ingots, magnesium ingots, Al-20Si alloy, Al-10Zr alloy, and Al-10Er alloy are weighed as raw materials;

[0014] (2) Melting: heating and melting the aluminum ingot, and then adding the magnesium ingot, Al-20Si alloy, Al-10Zr alloy, and Al-10Er alloy to form an aluminum alloy melt;

[0015] (3) Refining and casting: The aluminum alloy melt is refined with a refining agent to remove impurities in the furnace, and the aluminum alloy melt is cast to form an ingot plate;

[0016] Step 2: The ingot plate is homogenized, rolled once, heat treated once, rolled twice, and heat treated twice to obtain Al-Mg-Si-Zr-Er aluminum alloy.

[0017] Furthermore, in step (2), the smelting temperature is 720-780°C.

[0018] Furthermore, in step 2, the homogenization treatment is to heat the ingot plate obtained in step 1 to 490-540° C. and keep it warm for 8-14 hours, then cool it to room temperature, remove the oxide scale and mill the surface.

[0019] Furthermore, in step 2, the first rolling is to keep the ingot plate after homogenization treatment at 430-480°C for 1-3h, and then perform three hot rolling. After each hot rolling, the hot rolled plate is kept at 430-480°C for 10-60min. After hot rolling, the plate is intermediate annealed at 430-480°C for 1-2h, and then cold rolled for three times.

[0020] Furthermore, the primary heat treatment in step 2 is to sequentially subject the alloy plate obtained after the primary rolling to a solid solution treatment and a high temperature aging treatment.

[0021] Furthermore, the solution treatment is to place the alloy plate obtained after the first rolling at 520-570° C. for 1-2 hours, and then water quench.

[0022] Furthermore, the high temperature aging is to keep the plate after solution treatment at 380-420° C. for 1-2 hours.

[0023] Furthermore, in step 2, the secondary rolling is performed according to the actual thickness of the alloy plate and the equipment conditions, and the rolling deformation of the high temperature aging alloy is set to 60-80%, and a multi-pass rolling process is adopted, with the deformation of each pass controlled at 15-20%.

[0024] Furthermore, the secondary heat treatment in step 2 is to perform low-temperature aging treatment on the alloy plate obtained after the secondary rolling deformation, and the low-temperature aging is to age the plate at 170-210°C for 2-6h to obtain the final Al-Mg-Si-Zr-Er aluminum alloy.

[0025] The beneficial effects of the present invention are embodied in:

[0026] 1. The present invention prepares an Al-Mg-Si-Zr-Er alloy material with uniform microstructure and fine grains through composite microalloying, reasonable design of the content of other elements, and adoption of reasonable smelting process and deformation heat treatment technology, and the obtained material has good mechanical properties and electrical conductivity.

[0027] 2. The present invention effectively eliminates defects such as pores and shrinkage inside the ingot through a reasonable rolling process, makes the grain size distribution more uniform at the microscopic level, and improves the mechanical properties of the alloy at the macroscopic level; and the heat treatment further regulates the comprehensive properties of the alloy.

[0028] 3. The preparation process of the present invention includes two rollings and two heat treatments to control the existence form of alloy elements and the organizational structure of the aluminum alloy so that the role of each alloy element can be fully exerted.

[0029] 4. The alloy preparation process and deformation heat treatment method of the present invention are simple, and the preparation steps are increased. However, compared with the traditional process, the comprehensive performance of the alloy is higher, and it has significant energy-saving and consumption-reducing advantages. The production cost is not high, and there is no need to add new equipment or adjust the production steps of the existing production line. It can be used to produce deformed aluminum alloys with excellent comprehensive performance, and is easy to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of a method for preparing a high-strength conductive aluminum alloy provided in this application. DETAILED DESCRIPTION

[0031] The technical solutions of the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of them, and the protection scope of the present invention is not limited to the embodiments described below.

[0032] Example 1

[0033] like Figure 1 As shown, Al-Mg-Si-0.15Zr alloy was prepared according to the following steps

[0034] Step 1: Prepare alloy ingot plate

[0035] (1) Ingredients: According to the mass percentage of alloy elements: 98.05% Al, 0.8% Mg, 1% Si, and 0.15% Zr, pure aluminum, magnesium ingot, Al-20Si master alloy, and Al-10Zr master alloy are weighed and mixed, and the total mass of the ingredients is 200 g;

[0036] (2) Melting: The aluminum ingot from which the surface oxide impurities have been removed is dried and placed in a crucible, which is then heated to 750°C in a resistance furnace and kept warm for 30 minutes to melt. The temperature is then lowered to 720°C, followed by the addition of magnesium ingots, Al-20Si master alloy, and Al-10Zr master alloy that have been preheated to 200°C in a muffle furnace and kept warm for 30 minutes. After the alloy is completely melted, the melt is stirred for 5 minutes to make the alloy melt composition uniform, and then left to stand and kept warm for 10 minutes;

[0037] (3) Refining and casting: Add refining agent C to the melt. 2 C1 6 , add C 2 C1 6 The mass of C is 3% of the total mass of the ingredients. 2 C1 6 Immerse in the melt until no gas comes out, let it stand and keep warm for 10 minutes before removing the slag; cast the aluminum alloy melt to form an ingot plate.

[0038] Step 2: Homogenize the ingot plate

[0039] The alloy ingot plate obtained in step 1 was heated to 520°C and kept at this temperature for 12 hours, then furnace cooled to room temperature, the oxide scale was removed and the surface was milled to control the final thickness to be 15 mm.

[0040] Step 3: One Rolling

[0041] The homogenized ingot was kept at 470℃ for 1h, and then hot rolled in three passes on a two-roll hot rolling mill. After each pass of hot rolling, the hot rolled plate was kept at 470℃ for 10min. After hot rolling, the plate was intermediate annealed at 450℃ for 1h, and then cold rolled in three passes. The specific process is shown in Table 1.

[0042] Table 1 One-step rolling (cold rolling and hot rolling) process

[0043]

[0044] Step 4: Primary heat treatment

[0045] The primary heat treatment is to sequentially perform solution treatment and high temperature aging treatment on the alloy plate obtained after the primary rolling deformation:

[0046] Solution treatment: The rolled plate is kept at 540℃ for 1h, then water quenched to room temperature to obtain a solid solution alloy plate. The quenching transfer time is controlled within 15s and the water temperature is room temperature.

[0047] High temperature aging: The solution treated plate is kept at 400°C for 2h.

[0048] Step 5: Secondary rolling

[0049] The cold deformation of the alloy after high temperature aging is set to 80%. A multi-pass rolling process is adopted, and the deformation of each pass is controlled at 15-20%;

[0050] Step 6: Secondary Heat Treatment

[0051] The alloy sheet obtained after secondary rolling deformation is subjected to low temperature aging treatment:

[0052] Low temperature aging: The secondary rolled plate is aged at 180°C for 5 hours to obtain the final Al-Mg-Si-0.15Zr aluminum alloy.

[0053] In order to test the mechanical properties of Al-Mg-Si-0.15Zr alloy plate, a room temperature tensile test was carried out on the alloy plate. The specific steps are as follows: a standard tensile specimen was made along the direction of the alloy plate (rolling direction of the plate) according to the national standard GB6397-86 to obtain an alloy specimen. The mechanical properties of the obtained alloy specimen were tested on a universal testing machine at a tensile speed of 1 mm / min. Three groups of specimens were repeatedly measured as the average value. The obtained performance values ​​are shown in Table 2.

[0054] In order to test the conductivity of Al-Mg-Si-0.15Zr alloy plate, the room temperature was controlled at 20 °C, and a digital metal eddy current conductivity meter was used for conductivity measurement. The value was calibrated first, and then the conductivity of the front and back sides of the casting was measured. 15 groups were measured and the average value was taken. See Table 2 for details.

[0055] Example 2

[0056] This embodiment prepares Al-Mg-Si-0.3Er alloy material by the same steps as in Embodiment 1, except that:

[0057] In step (1), metal Al, Mg ingots, Al-20% Si master alloy and Al-10% Er master alloy are weighed and prepared according to the mass percentage of 97.9% Al, 0.8% Mg, 1% Si and 0.3% Er, and the total mass of the ingredients is 200 g;

[0058] The Al-Mg-Si-0.3Er alloy material was subjected to a room temperature tensile test in the same manner as in Example 1. The obtained mechanical property values ​​are shown in Table 2.

[0059] The electrical conductivity of the Al-Mg-Si-0.3Er alloy material was tested in the same manner as in Example 1. The obtained values ​​are shown in Table 2.

[0060] Example 3

[0061] This embodiment prepares Al-Mg-Si-0.15Zr-0.3Er alloy material by the same steps as in Embodiment 1, except that:

[0062] In step (1), according to the mass percentage of 97.75% Al, 0.8% Mg, 1% Si, 0.15% Zr and 0.3% Er, metal Al, Mg ingot, Al-20% Si master alloy, Al-10Zr master alloy and Al-10% Er master alloy are weighed and mixed, and the total mass of the mixed materials is 200g;

[0063] The Al-Mg-Si-0.15Zr-0.3Er alloy plate was subjected to a room temperature tensile test in the same manner as in Example 1. The obtained mechanical property values ​​are shown in Table 2.

[0064] The electrical conductivity of the Al-Mg-Si-0.15Zr-0.3Er alloy plate was tested in the same manner as in Example 1. The obtained values ​​are shown in Table 2.

[0065] Comparative Example

[0066] In this comparative example, an Al-Mg-Si alloy material was prepared by the same steps as in Example 3, in order to compare the effects of adding transition element Zr and rare earth element Er alone and in combination on the properties of the Al-Mg-Si alloy material. The only difference is that in step (1), metal Al, Mg ingots, and Al-20% Si master alloy were weighed and prepared according to the mass percentage of 98.2% Al, 0.8% Mg, and 1% Si, and the total mass of the ingredients was 200 g;

[0067] The Al-Mg-Si alloy plate was subjected to a room temperature tensile test in the same manner as in Example 1. The obtained mechanical property values ​​are shown in Table 2.

[0068] The electrical conductivity of the Al-Mg-Si alloy plate was tested in the same manner as in Example 1, and the obtained values ​​are shown in Table 2.

[0069] The alloy composition of each example is shown in Table 3

[0070] Table 2 Mechanical properties and electrical conductivity of alloy plates obtained in Examples 1-3 and Comparative Examples

[0071]

[0072] Table 3 Alloy composition of Examples 1-3 and Comparative Examples

[0073] Sample Al(％) Mg(%) Si(%) Zr(％) Er(％) Example 1 98.05 0.8 1 0.15 / Example 2 97.9 0.8 1 / 0.3 Example 3 97.75 0.8 1 0.15 0.3 Comparative Example 98.2 0.8 1 / /

[0074] Comparing the mechanical properties and electrical conductivity of alloy materials with different added elements, it can be seen from Table 2 that adding Zr or Er can significantly improve the strength and elongation of Al-Mg-Si alloy. This is mainly because adding Zr or Er can refine the alloy recrystallization structure. Grain refinement can simultaneously improve strength and plasticity. The combined addition of 0.15% Zr and 0.3% Er can greatly strengthen the alloy. The strengthening can be summarized as work hardening, grain refinement, solid solution strengthening and second phase strengthening. Among them, the second phase strengthening includes dispersion strengthening and precipitation strengthening, and the second phase strengthening mechanism is the orowan bypass strengthening mechanism. During the low temperature aging process, the electrical conductivity gradually increases, which is mainly due to Mg 2 The precipitation of Si strengthening phase causes Mg 2 The Si strengthening phase is finer and more dispersed. This is because after solid solution and artificial aging treatment, the Al-Mg-Si-0.15Zr-0.3Er alloy has uniform structure and fine grains, so it has good formability.

[0075] The above is a detailed introduction to the aluminum alloy manufacturing method provided by the present application. For those skilled in the art, according to the idea of ​​the embodiments of the present application, there will be changes in the specific implementation and application scope. In summary, the content of this specification should not be understood as limiting the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a high-strength and high-conductivity Al-Mg-Si-Zr-Er alloy, Features: The Al-Mg-Si-Zr-Er alloy has the following components in mass percentage: Mg 0.65-0.8%, Si 0.7-1%, Zr 0.1-0.15%, Er 0.1-0.3%, and the balance is Al and other inevitable impurities; The method for preparing the high-strength and high-conductivity Al-Mg-Si-Zr-Er alloy comprises the following steps: Step 1: Prepare alloy ingot plate (1) Ingredients: According to the mass percentage of alloy elements, aluminum ingots, magnesium ingots, Al-20Si alloy, Al-10Zr alloy, and Al-10Er alloy are weighed as raw materials; (2) Melting: heating and melting the aluminum ingot, and then adding the magnesium ingot, Al-20Si alloy, Al-10Zr alloy, and Al-10Er alloy to form an aluminum alloy melt; (3) Refining and casting: The aluminum alloy melt is refined with a refining agent to remove impurities in the furnace, and the aluminum alloy melt is cast to form an ingot plate; Step 2: performing homogenization treatment, primary rolling, primary heat treatment, secondary rolling, and secondary heat treatment on the ingot plate to obtain Al-Mg-Si-Zr-Er aluminum alloy; In step 2, the homogenization treatment is to heat the ingot plate obtained in step 1 to 490-540°C and keep it at this temperature for 8-14 hours, then cool it to room temperature, remove the oxide scale and mill the surface; In step 2, the first rolling is to heat the homogenized ingot plate at 430-480°C for 1-3 hours, and then perform three hot rolling. After each hot rolling, the hot rolled plate is kept at 430-480°C for 10-60 minutes. After hot rolling, the plate is intermediate annealed at 430-480°C for 1-2 hours, and then cold rolled for three times. The primary heat treatment in step 2 is to sequentially perform a solution treatment and a high temperature aging treatment on the alloy plate obtained after the primary rolling; The solution treatment is to place the alloy plate obtained after the first rolling at 540-570°C for 1-2 hours and then water quench; The high temperature aging is to keep the plate after solution treatment at 380-420°C for 1-2h; The secondary rolling in step 2 is based on the actual thickness of the alloy plate and the equipment conditions, and the rolling deformation of the high temperature aging alloy is set to 60-80%, and a multi-pass rolling process is adopted, and the deformation of each pass is controlled at 15-20%; The secondary heat treatment in step 2 is to perform low-temperature aging treatment on the alloy plate obtained after the secondary rolling deformation, and the low-temperature aging is to age the plate at 170-210°C for 2-6 hours to obtain the final Al-Mg-Si-Zr-Er aluminum alloy.

2. The method for preparing the high-strength and high-conductivity Al-Mg-Si-Zr-Er alloy according to claim 1, Features: The smelting temperature in step (2) is 720-780°C.

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