A method of homogenization heat treatment of an al-mg-si alloy ingot

Abstract

The application discloses a homogenization heat treatment method of Al-Mg-Si alloy ingot, and the Al-Mg-Si alloy ingot is subjected to one-time medium-temperature hot rolling pre-deformation and then is subjected to homogenization treatment. The application has the advantages that the tensile strength of the obtained Al-Mg-Si alloy ingot reaches 152 MPa-160 MPa, the elongation at break is 29%-32%, and the elongation is excellent; the grain size of the alloy organization is obviously reduced, and most of the needle-like beta-AlFeSi phases are transformed into the dispersedly distributed alpha-AlFeSi phases, the size and volume fraction of the hard and brittle beta-AlFeSi phases are reduced, and the harmfulness of the hard and brittle beta-AlFeSi phases is reduced.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy heat treatment technology, and in particular to a homogenization heat treatment method for Al-Mg-Si alloy ingots. Background Technology

[0002] Low-alloy Al-Mg-Si aluminum alloys, typified by high-conductivity 6101 aluminum alloy, possess good strength, weldability, and excellent conductivity. In recent years, they have been widely used in high-strength conductive materials and busbar conductors, including in new energy vehicle charging piles and conductive plates. Therefore, high-conductivity Al-Mg-Si alloys have become the latest development trend in the application of conductive materials for new energy vehicles internationally.

[0003] In the preparation of highly conductive Al-Mg-Si alloys, the cast ingots often undergo a series of processes including homogenization, rolling, solution treatment, and aging to obtain a final product with stable mechanical properties and excellent electrical conductivity. Homogenization is a crucial step affecting product performance. This is because the high cooling rate during the solidification of Al-Mg-Si alloy ingots leads to uneven element distribution, forming a low-melting-point second phase that accumulates at grain boundaries, resulting in severe compositional segregation. The Al-Mg-Si alloy ingots contain a large amount of coarse, brittle, and hard acicular β-AlFeSi phase, which exhibits strong thermal shrinkage, easily causing cracks and significant hot brittleness. It can also act as a stress concentration source, reducing the alloy's strength and plasticity. The purpose of homogenization is to dissolve the segregated elements at grain boundaries into the matrix as much as possible, reducing compositional segregation.

[0004] However, when the Mn content in Al-Mg-Si alloy is less than 0.01%, during the conventional homogenization heat treatment of Al-Mg-Si aluminum alloy ingots (holding at 560℃ for 8-10 hours), only a small amount of primary hard and brittle β-AlFeSi phase can undergo phase transformation, transforming into a small amount of discontinuously distributed granular α-AlFeSi phase. A large amount of needle-like β-AlFeSi phase remains distributed on the grain boundaries, which, as a hard phase, can easily lead to cracking and other problems during subsequent rolling, thus impairing the overall performance of the plate. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a homogenization heat treatment method for Al-Mg-Si alloy ingots, which significantly reduces the grain size of the alloy structure, and most of the acicular β-AlFeSi phases undergo phase transformation into dispersed α-AlFeSi phases, thereby reducing the size and volume fraction of the hard and brittle β-AlFeSi phases.

[0006] To solve the above-mentioned technical problems, the present invention provides a homogenization heat treatment method for Al-Mg-Si alloy ingots, which involves performing a medium-temperature hot rolling pre-deformation on the Al-Mg-Si alloy ingots, followed by homogenization treatment.

[0007] Furthermore, the method for pre-deformation of Al-Mg-Si alloy ingot by medium-temperature hot rolling is as follows: the Al-Mg-Si alloy ingot is heated to 300℃-400℃, held for 25min-35min, and then rolled, with a deformation amount of 28%-33%.

[0008] Furthermore, the method for pre-deformation of the Al-Mg-Si alloy ingot by hot rolling is as follows: the Al-Mg-Si alloy ingot is heated to 350°C, held for 30 minutes, and then rolled, with a deformation of 33%.

[0009] Furthermore, the homogenization treatment method is as follows: the pre-deformed Al-Mg-Si alloy ingot is kept at 540℃-560℃ for 6h-7h, and then air-cooled to room temperature.

[0010] Furthermore, the homogenization treatment method is as follows: the pre-deformed Al-Mg-Si alloy ingot is kept at 560℃ for 6 hours, and then air-cooled to room temperature.

[0011] Furthermore, the homogenization process is as follows: first, the homogenization furnace is preheated to 350℃-400℃, then the pre-deformed Al-Mg-Si alloy ingot is placed into the homogenization furnace, and the timing is started after the furnace temperature reaches the homogenization treatment temperature and stabilizes.

[0012] Furthermore, the mass fraction of Mn in the Al-Mg-Si alloy is less than 0.01%.

[0013] Furthermore, the composition of the Al-Mg-Si alloy ingot, by mass percentage, is as follows: Mg: 0.38%-0.50%, Si: 0.32%-0.48%, Fe≤0.11%, Cu≤0.01%, Mn<0.01%, Zn≤0.02%, Cr≤0.001%, Ti≤0.01%, with the balance being Al and unavoidable impurities.

[0014] Beneficial effects of this invention: (1) The Al-Mg-Si alloy ingots obtained by the method of this invention have a tensile strength of 152MPa-160MPa and a fracture elongation of 29%-32%, exhibiting excellent elongation. After one pre-deformation by medium-temperature hot rolling, the Al-Mg-Si alloy ingots undergo ingot homogenization treatment, resulting in a significant reduction in grain size. Furthermore, most of the acicular β-AlFeSi phases undergo phase transformation, converting into dispersed α-AlFeSi phases, thus reducing the size and volume fraction of the hard and brittle β-AlFeSi phase and mitigating its harmfulness. The granular α-AlFeSi phase can withstand higher stresses and exhibits excellent elongation and hot working properties, providing favorable conditions for further improving the overall performance of Al-Mg-Si alloy plates and demonstrating promising application prospects.

[0015] (2) The optimization method provided by the present invention, compared with the conventional homogenization process, shortens the heat treatment time, improves the utilization rate of heat treatment equipment, reduces production energy consumption, improves production efficiency, and reduces production costs, and has good market prospects. Attached Figure Description

[0016] Figure 1 The image shows the initial SEM morphology of the Al-Mg-Si alloy ingot. Figure 2 The image shows the SEM morphology of the alloy ingot prepared in Example 1. Figure 3 The image shows the SEM morphology of the alloy ingot prepared in Example 2. Figure 4 The image shows the SEM morphology of the alloy ingot prepared in Example 3. Figure 5 The image shows the SEM morphology of the alloy ingot prepared in Comparative Example 1. Figure 6 Metallographic photograph of the initial Al-Mg-Si alloy ingot; Figure 7 Metallographic photograph of the alloy ingot prepared in Example 2; Figure 8 Metallographic photograph of the alloy ingot prepared in Comparative Example 1. Detailed Implementation

[0017] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0018] Example 1

[0019] A method for homogenizing Al-Mg-Si alloy ingots includes the following steps: S1. Medium-temperature hot rolling pre-deformation: The Al-Mg-Si alloy ingot is heated to 300℃, held for 35 minutes, and then rolled with a deformation of 28%. The composition of the Al-Mg-Si alloy ingot, by mass percentage, includes: Mg=0.40%, Si=0.46%, Fe=0.11%, Mn=0.003%, Cu≤0.01%, Zn≤0.02%, Cr≤0.001%, Ti≤0.01%, with the balance being Al and unavoidable impurities. The Al-Mg-Si alloy ingot is produced by smelting and semi-continuous casting of electrolytic aluminum.

[0020] S2. Homogenization treatment: Preheat the homogenization furnace to 350℃, then put the pre-deformed Al-Mg-Si alloy ingot into the homogenization furnace. Start timing when the furnace temperature rises to 550℃, hold for 7 hours and then remove it, and then air cool to room temperature.

[0021] Example 2

[0022] A method for homogenizing Al-Mg-Si alloy ingots includes the following steps: S1. Medium-temperature hot rolling pre-deformation: The Al-Mg-Si alloy ingot is heated to 350℃, held for 30 minutes, and then rolled with a deformation of 33%. The composition of the Al-Mg-Si alloy ingot, by mass percentage, includes: Mg=0.40%, Si=0.46%, Fe=0.11%, Mn=0.003%, Cu≤0.01%, Zn≤0.02%, Cr≤0.001%, Ti≤0.01%, with the balance being Al and unavoidable impurities. The Al-Mg-Si alloy ingot is produced by smelting and semi-continuous casting of electrolytic aluminum.

[0023] S2. Homogenization treatment: Preheat the homogenization furnace to 350℃, then put the pre-deformed Al-Mg-Si alloy ingot into the homogenization furnace. Start timing when the furnace temperature rises to 560℃, hold for 6 hours and then remove it from the furnace. Then air cool to room temperature.

[0024] Example 3

[0025] A method for homogenizing Al-Mg-Si alloy ingots includes the following steps: S1. Medium-temperature hot rolling pre-deformation: The Al-Mg-Si alloy ingot is heated to 400℃, held for 25 minutes, and then rolled with a deformation of 30%. The composition of the Al-Mg-Si alloy ingot, by mass percentage, includes: Mg=0.40%, Si=0.46%, Fe=0.11%, Mn=0.003%, Cu≤0.01%, Zn≤0.02%, Cr≤0.001%, Ti≤0.01%, with the balance being Al and unavoidable impurities. The Al-Mg-Si alloy ingot is produced by smelting and semi-continuous casting of electrolytic aluminum.

[0026] S2. Homogenization treatment: Preheat the homogenization furnace to 400℃, then put the pre-deformed Al-Mg-Si alloy ingot into the homogenization furnace. Start timing when the furnace temperature rises to 540℃, hold for 7 hours and then remove it from the furnace. Then air cool to room temperature.

[0027] Comparative Example 1 A conventional heat treatment method for homogenizing Al-Mg-Si aluminum alloy ingots includes the following steps: The homogenizing furnace was preheated to 350℃, and then the Al-Mg-Si alloy ingot was placed in the furnace. Timing began when the furnace temperature reached 560℃, and the ingot was held at that temperature for 8 hours before being removed and air-cooled to room temperature. The composition of the Al-Mg-Si alloy ingot, by mass percentage, included: Mg=0.40%, Si=0.46%, Fe=0.11%, Mn=0.003%, Cu≤0.01%, Zn≤0.02%, Cr≤0.001%, Ti≤0.01%, with the balance being Al and unavoidable impurities. The Al-Mg-Si alloy ingot was produced by smelting molten aluminum using electrolytic aluminum and then semi-continuous casting.

[0028] Experiment 1 To observe the differences in the microstructure of the alloys prepared according to this invention, SEM images were taken of the initial Al-Mg-Si alloy ingot, the ingots prepared in Examples 1-3, and Comparative Example 1, as follows: Figure 1-5 As shown. Metallographic photographs were taken of the initial Al-Mg-Si alloy ingot, Example 2, and Comparative Example 1, as follows. Figure 6-8 As shown.

[0029] Combination Figure 1-5 It can be seen that the acicular β-AlFeSi phase in the alloy microstructure prepared in Examples 1-3 is essentially transformed into a finer, more dispersed granular α-AlFeSi phase. Combined with... Figure 6-8 It can be seen that, compared with the initial Al-Mg-Si alloy ingot and Comparative Example 1, the grain size of Example 2 is significantly reduced.

[0030] Experiment 2 To verify the mechanical properties of the alloy microstructure prepared by the present invention, mechanical tests were conducted on the ingots prepared in Examples 1-3 and Comparative Example 1, respectively. The tensile strength and elongation at break were tested, and the test results are shown in the table below: Tensile strength (MPa) 150-153 156-160 156-158 150-154 Elongation at break (%) 28.6-29.8 30.5-31.9 29.5-30.1 23.6-26.2 As can be seen from the table, the alloy ingots prepared in Examples 1-3 have a tensile strength of 152MPa-160MPa and a fracture elongation of 29%-32%. Compared with Comparative Example 1, the elongation is significantly improved, and the tensile strength is also slightly improved.

[0031] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A homogenization heat treatment method for Al-Mg-Si alloy ingots, characterized in that: The Al-Mg-Si alloy ingot is pre-deformed by medium-temperature hot rolling and then homogenized. The method for pre-deformation of Al-Mg-Si alloy ingots by medium-temperature hot rolling is as follows: the Al-Mg-Si alloy ingots are heated to 300℃-400℃, held at that temperature for 25min-35min, and then rolled, with a deformation of 28%-33%; The homogenization process is as follows: the pre-deformed Al-Mg-Si alloy ingot is kept at 540℃-560℃ for 6-7 hours, and then air-cooled to room temperature. The composition of the Al-Mg-Si alloy ingot, by mass percentage, includes: Mg: 0.38%-0.50%, Si: 0.32%-0.48%, Fe≤0.11%, Cu≤0.01%, Mn<0.01%, Zn≤0.02%, Cr≤0.001%, Ti≤0.01%, with the balance being Al and unavoidable impurities.

2. The homogenization heat treatment method for Al-Mg-Si alloy ingots according to claim 1, characterized in that: The method for pre-deformation of Al-Mg-Si alloy ingot by medium-temperature hot rolling is as follows: the Al-Mg-Si alloy ingot is heated to 350℃, held for 30 minutes, and then rolled, with a deformation of 33%.

3. The homogenization heat treatment method for Al-Mg-Si alloy ingots according to claim 1, characterized in that: The homogenization process involves placing the pre-deformed Al-Mg-Si alloy ingot at 560°C for 6 hours and then air-cooling it to room temperature.

4. The homogenization heat treatment method for Al-Mg-Si alloy ingots according to claim 1, characterized in that: The homogenization process is as follows: first, preheat the homogenization furnace to 350℃-400℃, then place the pre-deformed Al-Mg-Si alloy ingot into the homogenization furnace, and start timing after the furnace temperature reaches the homogenization treatment temperature and stabilizes.

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