A medium-strength and highly conductive aluminum alloy sheet and its preparation method

Abstract

A medium-strength and high-conductivity aluminum alloy sheet and its preparation method, which relate to an aluminum alloy sheet and its preparation method. The purpose of the present invention is to solve the technical problem that when other alloying elements are added to existing aluminum alloys to improve the mechanical properties of the alloy, its electrical conductivity will be sacrificed. The medium-strength and high-conductivity aluminum alloy sheet includes the following components by weight percentage: Mg: 0.45-0.53%, Si: 0.4-0.46%, Cu: 0.1-0.5%, Fe≤0.16%, Zn≤0.01%, Mn≤0.03%, Cr≤0.02%, and the balance is impurities and Al. Method: First, prepare an aluminum alloy ingot; second, perform heat treatment; third, perform rolling; fourth, perform solution aging treatment. The electrical conductivity of the medium-strength and high-conductivity aluminum alloy sheet prepared by the present invention is above 53% IACS, while the hardness is higher than 75 HV and the tensile strength is higher than 187 MPa. The present invention can obtain a medium-strength and high-conductivity aluminum alloy sheet.

Description

Technical Field

[0001] The present invention relates to an aluminum alloy sheet and a preparation method thereof. Background Art

[0002] Currently, Cu alloys are mainly used as conductor materials for new energy vehicles. For decades, the large-scale use of copper has led to a shortage of copper resources and an increase in costs. The application trend of "using aluminum to save copper" for conductor materials varies among countries around the world, but generally shows a progressive development. Abroad, aluminum alloy materials have been used for substitution. Some automobile manufacturers have changed the wires for charging piles to aluminum alloy materials (6101 alloy) and are planning to change the conductors used in automobiles to aluminum alloy as well to achieve the purpose of weight reduction. In the actual application process of aluminum conductors, compared with copper conductors, the power transmission loss is comparable, and the current-carrying capacity can also be designed and achieved according to actual situations. Against this background, researching and developing high-conductivity aluminum alloy materials will be an important development trend in the near future. For conductive aluminum alloys, both the mechanical properties of the alloy and the conductivity of the material need to be considered to achieve a good match of material properties.

[0003] Al-Mg-Si series aluminum alloys are widely used in the automotive, power, and electrical industries due to their moderate strength, good plasticity, corrosion resistance, and excellent electrical conductivity. Among them, 6101 aluminum alloy is widely used in the field of electrical drive for manufacturing wires, conductive tracks, electrical equipment, etc. due to its good conductivity and strength. The mechanical properties and electrical conductivity of the alloy are mainly affected by the second phase and solutes in the alloy. The increase in solute concentration improves the mechanical properties at the expense of a decrease in electrical conductivity, and the mechanical properties and electrical conductivity can be improved by adjusting the morphology and dispersion of the second phase. After short-term aging of Al-Mg-Si series aluminum alloys, the hardness increases significantly. The hardening is due to the formation of a large number of nano-scale and metastable precipitation phases distributed throughout the Al matrix.

[0004] Most of the existing technologies improve the mechanical properties of aluminum alloy conductors at the expense of the conductivity of the aluminum alloy conductors, which is not conducive to the exertion of the comprehensive performance of aluminum alloy conductors. Generally speaking, the introduction of alloying elements will change the order degree of the aluminum matrix, cause lattice distortion of the aluminum matrix, increase the electron scattering effect, and reduce the electrical conductivity. How to improve the strength without affecting the electrical conductivity of aluminum alloys requires a reasonable selection of the types and addition amounts of alloying elements. Summary of the Invention

[0005] The purpose of the present invention is to solve the technical problem that when other alloying elements are added to existing aluminum alloys to improve the mechanical properties of the alloy, the electrical conductivity thereof will be sacrificed, and to provide a medium-strength and high-conductivity aluminum alloy sheet and a preparation method thereof.

[0006] A medium-strength and high-conductivity aluminum alloy sheet, characterized in that the medium-strength and high-conductivity aluminum alloy sheet comprises the following components by weight percentage: Mg: 0.45-0.53%, Si: 0.4-0.46%, Cu: 0.1-0.5%, Fe≤0.16%, Zn≤0.01%, Mn≤0.03%, Cr≤0.02%, and the balance is impurities and Al.

[0007] A preparation method of a medium-strength and high-conductivity aluminum alloy sheet, which is specifically completed according to the following steps:

[0008] I. Preparation of an aluminum alloy ingot:

[0009] ①. Weigh 6101 aluminum alloy and Al-50Cu master alloy according to the weight percentage of Mg: 0.45-0.53%, Si: 0.4-0.46%, Cu: 0.1-0.5%, Fe≤0.16%, Zn≤0.01%, Mn≤0.03%, Cr≤0.02%, and the balance is impurities and Al to obtain raw materials;

[0010] ②. Put the 6101 aluminum alloy into a crucible, heat it electrically in a furnace, control the furnace temperature at 750°C. After the 6101 aluminum alloy is completely melted, skim off the floating slag, add the Al-50Cu master alloy into the crucible, keep it warm. After all the raw materials are melted, obtain aluminum alloy liquid; add a refining agent to the aluminum alloy liquid at a temperature of 730-750°C for refining. After degassing and slag removal, cast at 720-730°C to obtain an aluminum alloy ingot;

[0011] II. Heat treatment:

[0012] Perform homogenization treatment on the aluminum alloy ingot to obtain a heat-treated aluminum alloy ingot;

[0013] III. Rolling:

[0014] ①. Cut the heat-treated aluminum alloy ingot to obtain a rolling blank;

[0015] ②. Heat and keep warm the rolling blank, then perform hot rolling and cold rolling to obtain an aluminum alloy rolled sheet;

[0016] IV. Solution aging treatment:

[0017] Perform solution and aging treatment on the aluminum alloy rolled sheet to obtain a medium-strength and high-conductivity aluminum alloy sheet.

[0018] The principle of the present invention:

[0019] 1. The addition of Cu in the present invention can change the precipitation type during artificial aging of the alloy, significantly improving the aging hardening kinetics of the Al-Mg-Si alloy; after the Cu content, the activation energy of the strengthening phase β' of the alloy decreases, making it easier to precipitate, shortening the time to reach the hardness peak point; saving material processing time; the addition of Cu makes the precipitated phase finer and more dispersed within a certain range, thereby improving the strength of the alloy;

[0020] 2. The present invention restores the internal lattice structure of the alloy through solution treatment, removes the lattice defects formed during the alloy processing, and improves the performance; performs aging treatment on the solution-treated alloy to promote the precipitation of the Mg2Si strengthening phase, increasing the strength of the alloy and simultaneously reducing the solid solubility to improve the electrical conductivity of the alloy.

[0021] Advantages of the present invention:

[0022] The electrical conductivity of the medium-strength and high-conductivity aluminum alloy sheet prepared by the present invention is above 53% IACS, while the hardness is higher than 75 HV and the tensile strength is higher than 187 MPa; enabling the aluminum alloy sheet to have enhanced mechanical properties while taking into account high electrical conductivity performance. Description of the drawings

[0023] Figure 1 Digital photo of the medium-strength and high-conductivity aluminum alloy sheet prepared in Example 1;

[0024] Figure 2 Microstructure diagram of the medium-strength and high-conductivity aluminum alloy sheet prepared in Example 1. Detailed implementation manners

[0025] Detailed implementation manner 1: A medium-strength and high-conductivity aluminum alloy sheet in this implementation manner includes the following components by weight percentage: Mg: 0.45 - 0.53%, Si: 0.4 - 0.46%, Cu: 0.1 - 0.5%, Fe ≤ 0.16%, Zn ≤ 0.01%, Mn ≤ 0.03%, Cr ≤ 0.02%, and the balance is impurities and Al.

[0026] Detailed implementation manner 2: The difference between this implementation manner and detailed implementation manner 1 is that the content of a single impurity in the medium-strength and high-conductivity aluminum alloy sheet is less than 0.03%, and the total impurity content is less than 0.1%; the thickness of the medium-strength and high-conductivity aluminum alloy sheet is 2 - 2.5 mm. Other steps are the same as those in detailed implementation manner 1.

[0027] Specific Embodiment 3: The difference between this embodiment and one of Specific Embodiments 1 or 2 is that the medium-strength and high-conductivity aluminum alloy sheet includes the following components by weight percentage: Mg: 0.53%, Si: 0.46%, Cu: 0.5%, Fe: 0.16%, Zn: 0.01%, Mn: 0.03%, Cr: 0.02%, and the balance is impurities and Al. Other steps are the same as those in Specific Embodiment 1 or 2.

[0028] Specific Embodiment 4: The difference between this embodiment and one of Specific Embodiments 1 to 3 is that the medium-strength and high-conductivity aluminum alloy sheet includes the following components by weight percentage: Mg: 0.53%, Si: 0.46%, Cu: 0.11%, Fe: 0.16%, Zn: 0.01%, Mn: 0.03%, Cr: 0.02%, and the balance is impurities and Al. Other steps are the same as those in Specific Embodiments 1 to 3.

[0029] Specific Embodiment 5: A method for preparing a medium-strength and high-conductivity aluminum alloy sheet, which is specifically completed according to the following steps:

[0030] I. Preparation of aluminum alloy ingot:

[0031] ①. Weigh 6101 aluminum alloy and Al-50Cu master alloy according to the weight percentage of Mg: 0.45 - 0.53%, Si: 0.4 - 0.46%, Cu: 0.1 - 0.5%, Fe ≤ 0.16%, Zn ≤ 0.01%, Mn ≤ 0.03%, Cr ≤ 0.02%, and the balance is impurities and Al to obtain raw materials;

[0032] ②. Put the 6101 aluminum alloy into a crucible, heat it electrically in the furnace, control the furnace temperature at 750°C. After the 6101 aluminum alloy is completely melted, skim off the floating slag, add the Al-50Cu master alloy into the crucible, keep it warm. After all the raw materials are melted, obtain aluminum alloy liquid; Add a refining agent to the aluminum alloy liquid at a temperature of 730 - 750°C for refining. After degassing and slag removal, cast at 720 - 730°C to obtain an aluminum alloy ingot;

[0033] II. Heat treatment:

[0034] Perform homogenization treatment on the aluminum alloy ingot to obtain a heat-treated aluminum alloy ingot;

[0035] III. Rolling:

[0036] ①. Cut the heat-treated aluminum alloy ingot to obtain rolling blanks;

[0037] ②. Heat and keep the rolling blanks warm, then perform hot rolling and cold rolling to obtain aluminum alloy rolled sheets;

[0038] IV. Solution aging treatment:

[0039] The aluminum alloy rolling sheet is subjected to solution treatment and aging treatment to obtain a medium-strength and high-conductivity aluminum alloy sheet.

[0040] Specific Embodiment 6: The difference between this embodiment and one of Embodiments 1 to 5 is as follows: In step 1②, the Al-50Cu master alloy is added into the crucible and kept warm for 30 min to 40 min; the refining time in step 1② is 20 min to 30 min; the refining agent in step 1② is hexachloroethane; the addition amount of the refining agent is 0.3% of the weight percentage of the raw materials weighed in step 1. Other steps are the same as those in Embodiments 1 to 5.

[0041] Specific Embodiment 7: The difference between this embodiment and one of Embodiments 1 to 6 is as follows: The homogenization treatment method in step 2 is: placing the aluminum alloy ingot in a heating furnace, heating it to 520 - 540 °C, keeping it warm for 7 h to 8 h, and then taking it out of the furnace and air-cooling it. Other steps are the same as those in Embodiments 1 to 6.

[0042] Specific Embodiment 8: The difference between this embodiment and one of Embodiments 1 to 7 is as follows: The thickness of the rolling blank in step 3① is 10 mm; before heat preservation of the rolling blank in step 3②, the surface oxide layer and impurities of the rolling blank are removed with sandpaper to keep the surface clean; the heating and heat preservation temperature in step 3② is 530 - 540 °C, and the heating and heat preservation time is 20 min to 30 min. Other steps are the same as those in Embodiments 1 to 7.

[0043] Specific Embodiment 9: The difference between this embodiment and one of Embodiments 1 to 8 is as follows: The hot rolling in step 3② is carried out in 3 passes, the reduction rate per pass is 20 - 25%, the hot rolling temperature is 500 - 520 °C, and the heat preservation time between hot rolling passes is 5 - 10 min; the cold rolling in step 3② is carried out in 2 passes, and the reduction rate per pass is 20 - 30%. Other steps are the same as those in Embodiments 1 to 8.

[0044] Specific Embodiment 10: The difference between this embodiment and one of Embodiments 1 to 9 is as follows: The solution aging treatment process in step 4 is: the solution temperature is 520 - 550 °C, the solution heat preservation time is 0.7 - 0.8 h, and the quenching method is water quenching; the aging treatment temperature is 170 - 180 °C, and the aging treatment heat preservation time is 7 - 8 h. Other steps are the same as those in Embodiments 1 to 9.

[0045] The following examples are used to verify the beneficial effects of the present invention:

[0046] Example 1: A preparation method of a medium-strength and high-conductivity aluminum alloy sheet is completed according to the following steps:

[0047] I. Preparation of Aluminum Alloy Ingot:

[0048] ①. Weigh 6101 aluminum alloy and Al-50Cu master alloy according to the weight percentages: Mg: 0.53%, Si: 0.46%, Cu: 0.5%, Fe: 0.16%, Zn: 0.01%, Mn: 0.03%, Cr: 0.02%, with the balance being impurities and Al, to obtain the raw materials.

[0049] ②. Put the 6101 aluminum alloy into a crucible and heat it electrically in the furnace. Control the furnace temperature at 750°C. After the 6101 aluminum alloy is completely melted, skim off the floating slag, add the Al-50Cu master alloy into the crucible, and keep it warm for 30 minutes. After all the raw materials are melted, obtain the aluminum alloy liquid. Add a refining agent to the aluminum alloy liquid at 740°C for 20 minutes of refining. After degassing and slag removal, cast at 730°C to obtain the aluminum alloy ingot.

[0050] The refining agent described in step I② is hexachloroethane; the addition amount of the refining agent is 0.3% of the weight percentage of the raw materials weighed in step I.

[0051] II. Heat Treatment:

[0052] Carry out homogenization treatment on the aluminum alloy ingot to obtain the heat-treated aluminum alloy ingot.

[0053] The method of homogenization treatment described in step II is: place the aluminum alloy ingot in a heating furnace, raise the temperature to 540°C and keep it warm for 8 hours, then take it out of the furnace and air-cool.

[0054] III. Rolling:

[0055] ①. Cut the heat-treated aluminum alloy ingot to obtain a rolling blank with a thickness of 10 mm; use sandpaper to clean the surface oxide layer and impurities to keep the surface clean.

[0056] ②. Heat and keep the rolling blank warm, then carry out hot rolling and cold rolling to obtain the aluminum alloy rolling sheet.

[0057] The temperature of heating and keeping warm described in step III② is 540°C, and the time of heating and keeping warm is 20 minutes.

[0058] The hot rolling described in step III② is carried out in 3 passes, with a reduction ratio of 25% for each pass, a hot rolling temperature of 520°C, and a heat preservation of 10 minutes between hot rolling passes.

[0059] The cold rolling described in step III② is carried out in 2 passes, with a reduction ratio of 30% for each pass.

[0060] IV. Solution Aging Treatment:

[0061] The aluminum alloy rolling sheet is subjected to solution treatment and aging treatment to obtain a medium-strength and high-conductivity aluminum alloy sheet.

[0062] The process of the solution aging treatment described in step 4 is as follows: the solution temperature is 545 °C, the solution holding time is 0.75 h, and the quenching method is water quenching; the aging treatment temperature is 170 °C, and the aging treatment holding time is 8 h.

[0063] Example 2: The difference between this example and Example 1 is that in step 1①, 6101 aluminum alloy and Al-50Cu master alloy are weighed according to the weight percentages of Mg: 0.53%, Si: 0.46%, Cu: 0.11%, Fe: 0.16%, Zn: 0.01%, Mn: 0.03%, Cr: 0.02%, and the balance is impurities and Al. Other steps and parameters are the same as those in Example 1.

[0064] Example 3: The difference between this example and Example 1 is that in step 1①, 6101 aluminum alloy and Al-50Cu master alloy are weighed according to the weight percentages of Mg: 0.53%, Si: 0.46%, Cu: 0.11%, Fe: 0.16%, Zn: 0.01%, Mn: 0.03%, Cr: 0.02%, and the balance is impurities and Al; the process of the solution aging treatment described in step 4 is as follows: the solution temperature is 525 °C, the solution holding time is 0.75 h, and the quenching method is water quenching. Other steps and parameters are the same as those in Example 1.

[0065] Comparative Example 1: The difference between this example and Example 1 is that in step 1①, 6101 aluminum alloy and Al-50Cu master alloy are weighed according to the weight percentages of Mg: 0.53%, Si: 0.46%, Cu: 0.01%, Fe: 0.16%, Zn: 0.01%, Mn: 0.03%, Cr: 0.02%, and the balance is impurities and Al. Other steps and parameters are the same as those in Example 1.

[0066] The relevant performance test data of the medium-strength and high-conductivity aluminum alloy sheets prepared in Examples 1 to 3 and the aluminum alloy sheet prepared in Comparative Example 1 are shown in Table 1;

[0067] Table 1

[0068] Scheme Conductivity (%IACS) Hardness (HV) Tensile strength (MPa) Example 1 53.2 80.4 196 Example 2 54.0 77.2 191 Example 3 54.7 75.4 187 Comparative Example 1 53.3 71.7 176

[0069] It can be seen from the component, process flow and material performance data of Examples 1-3 and Comparative Example 1 in Table 1 that the examples of the present invention have obvious medium strength and high conductivity compared with other aluminum alloy sheets by adding an appropriate content of Cu element to 6101 aluminum alloy and a reasonable processing process, so that the mechanical properties of the material are improved without sacrificing the conductivity.

Claims

1. A preparation method of a medium-strength and high-conductivity aluminum alloy sheet, characterized in that The conductivity of the medium-strength and high-conductivity aluminum alloy sheet prepared by the preparation method is 53.2% IACS, the hardness is 80.4 HV, and the tensile strength is 196 MPa. The preparation method is specifically completed according to the following steps: I. Preparation of aluminum alloy ingot: ①. Weigh 6101 aluminum alloy and Al-50Cu master alloy according to the weight percentages of Mg: 0.53%, Si: 0.46%, Cu: 0.5%, Fe: 0.16%, Zn: 0.01%, Mn: 0.03%, Cr: 0.02%, and the balance being impurities and Al to obtain the raw materials; ②. Put the 6101 aluminum alloy into a crucible and heat it electrically in a furnace. Control the furnace temperature at 750 °C. After the 6101 aluminum alloy is completely melted, skim off the floating slag, add the Al-50Cu master alloy into the crucible, and keep it warm for 30 min. After all the raw materials are melted, obtain the aluminum alloy liquid; add a refining agent to the aluminum alloy liquid at a temperature of 740 °C for 20 min of refining. After degassing and slag removal, cast at 730 °C to obtain the aluminum alloy ingot; The refining agent described in step I ② is hexachloroethane; the addition amount of the refining agent is 0.3% of the weight percentage of the raw materials weighed in step I; II. Heat treatment: Perform homogenization treatment on the aluminum alloy ingot to obtain the heat-treated aluminum alloy ingot; The method of the homogenization treatment described in step II is: place the aluminum alloy ingot in a heating furnace, heat it up to 540 °C and keep it warm for 8 h, and then take it out of the furnace and air-cool it; III. Rolling: ①. Cut the heat-treated aluminum alloy ingot to obtain a rolling blank with a thickness of 10 mm; use sandpaper to clean the surface oxide layer and impurities to keep the surface clean; ②. Heat and keep the rolling blank warm, and then perform hot rolling and cold rolling to obtain the aluminum alloy rolled sheet; The temperature of the heating and heat preservation described in step III ② is 540 °C, and the time of the heating and heat preservation is 20 min; The hot rolling described in step III ② is carried out in 3 passes, with a reduction rate of 25% for each pass, a hot rolling temperature of 520 °C, and a heat preservation of 10 min between hot rolling passes; The cold rolling described in step III ② is carried out in 2 passes, with a reduction rate of 30% for each pass; IV. Solution aging treatment: Perform solution and aging treatments on the aluminum alloy rolled sheet to obtain the medium-strength and high-conductivity aluminum alloy sheet; The process of the solution aging treatment described in step IV is: the solution temperature is 545 °C, the solution heat preservation time is 0.75 h, and the quenching method is water quenching; the aging treatment temperature is 170 °C, and the aging treatment heat preservation time is 8 h.

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