Cast aluminum alloy and preparation method thereof

Abstract

The invention belongs to the field of aluminum alloy materials, and particularly relates to a cast aluminum alloy and a preparation method thereof. The aluminum alloy comprises the following components in percentage by weight: 4 to 7 percent of Cu, 0.2 to 0.7 percent of Si, 0.1 to 0.5 percent of Mg, 0.1 to 0.5 percent of Zr, 0.01 to 0.3 percent of Cr, 0.01 to 0.3 percent of Sc, 0.01 to 1 percent of Zn, 0.1 to 0.5 percent of Fe, 0.01 to 0.1 percent of Sn, less than or equal to 0.1 percent of Mn and the balance of Al. The cast aluminum alloy comprises Si, alpha-Fe, Al5Cu2Mg8Si6, Mg2Si, Al2Cu and AlSn phases, the preparation method comprises the steps of casting forming and heat treatment, the tensile strength of the aluminum alloy is 520-580 MPa, the yield strength is 480-500 MPa, and the elongation is 10-15%. According to the cast aluminum alloy and the preparation method, the obdurability and the corrosion resistance of the Al-Cu alloy are synchronously improved.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy materials, specifically relating to a cast aluminum alloy and its preparation method. Background Technology

[0002] With the rapid development of the new energy vehicle industry, aluminum alloy castings are being used more widely in automobile bodies and components. As the safety performance of automotive structural components increases, higher demands are being placed on the strength and toughness of aluminum alloys. Traditional cast Al-Si aluminum alloys are gradually failing to meet the lightweight requirements of modern automobiles, making it urgent to improve the comprehensive mechanical properties of cast aluminum alloys. Al-Cu alloys, due to their superior mechanical properties compared to Al-Si cast alloys and their ability to maintain excellent performance at high temperatures, are ideal materials to replace Al-Si alloys in the manufacture of automobile bodies and components. However, the poor corrosion resistance of traditional Al-Cu alloys and their inability to simultaneously possess high strength and high toughness limit their further development as automotive components.

[0003] Chinese invention patent CN 119144881A discloses a microalloying material for casting Al-Cu alloys and a heat treatment process. The material of this invention has a maximum yield strength of 371.5 MPa and a maximum tensile strength of 482.1 MPa, but the elongation is not higher than 8%, and the corrosion resistance of the alloy is not considered.

[0004] Chinese invention patent CN 119433310A discloses a high-strength, high-thermal-stability Al-Cu alloy and its preparation method. The method involves first melting and casting raw materials to obtain alloy ingots, then homogenizing the alloy ingots, cutting the ingots into aluminum rods, and hot-extruded them to obtain extruded profiles. Finally, the profiles undergo heat treatment. The heat-treated alloy exhibits high strength, toughness, and corrosion resistance; however, the entire alloy preparation process is complex and time-consuming. Summary of the Invention

[0005] The cast aluminum alloys and their preparation methods disclosed in the aforementioned patents improve the strength and toughness of the alloys to a certain extent, but they suffer from problems such as neglecting the corrosion resistance of the alloys or having complex preparation processes. Therefore, finding a simpler and more efficient preparation method that can achieve a synergistic improvement in the strength, toughness, and corrosion resistance of Al-Cu alloys is of great significance.

[0006] To address the aforementioned technical problems, this application provides the following technical solution:

[0007] This invention provides a cast aluminum alloy, which, by weight, is composed of the following elements: Cu 4-7%, Si 0.2-0.7%, Mg 0.1-0.5%, Zr 0.1-0.5%, Cr 0.01-0.3%, Sc 0.01-0.3%, Zn 0.01-1%, Fe 0.1%-0.5%, Sn 0.01%-0.1%, Mn ≤0.1%, with the remainder being Al and unavoidable impurity elements;

[0008] The cast aluminum alloy comprises eutectic Si, α-Fe, Al5Cu2Mg8Si6, Mg2Si, Al2Cu and AlSn phases, wherein the volume fraction of the Al2Cu phase is 0.1-1.8%, the volume fraction of the Al5Cu2Mg8Si6 phase is 0.1-1.2%, and the volume fraction of the eutectic Si is 0.01-0.2%. In the non-heat-treated state, the eutectic Si has a fibrous morphology, and the diameter of a single eutectic Si fiber is less than 3 μm.

[0009] Preferably, the yield strength of the cast aluminum alloy is 480-500 MPa.

[0010] Preferably, the tensile strength of the cast aluminum alloy is 520-580 MPa.

[0011] Preferably, the elongation of the cast aluminum alloy is 10-15%.

[0012] The present invention also provides a method for preparing the above-mentioned cast aluminum alloy, comprising the following steps:

[0013] S11: Aluminum alloy ingots are obtained by batching, smelting, and casting using pure Al, pure Cu, pure Mg, and intermediate alloys as raw materials;

[0014] By weight, the aluminum alloy ingot is composed of the following elements: Cu 4-7%, Si 0.2-0.7%, Mg 0.1-0.5%, Zr 0.1-0.5%, Cr 0.01-0.3%, Sc 0.01-0.3%, Zn 0.01-1%, Fe 0.1-0.5%, Sn 0.01-0.1%, Mn≤0.1%, with the remainder being Al and unavoidable impurity elements;

[0015] S12: The aluminum alloy ingot is subjected to solution treatment and aging treatment to obtain the cast aluminum alloy; the solution treatment steps are as follows:

[0016] S21: Heat the aluminum alloy ingot to 490-510℃ and hold for 8-14 hours;

[0017] S22: After the aluminum alloy ingot has been heat-preserved in S21, heat it to 515-530℃ and hold it for 5-9 hours before water quenching.

[0018] Preferably, the master alloy includes Al-20Si master alloy, Al-5Zr master alloy, Al-10Cr master alloy, Al-5Sc master alloy, Al-10Fe master alloy, Al-50Sn master alloy and Al-10Mn master alloy.

[0019] Preferably, in step S11, the casting method is selected from gravity casting, high pressure casting, squeeze casting, low pressure casting, or differential pressure casting.

[0020] Preferably, in step S21, the heating rate is 40-110°C per hour.

[0021] Preferably, in step S12, the aging treatment method is to keep the solution-treated aluminum alloy ingot at 150-180℃ for 10-15 hours.

[0022] The present invention also provides the application of the above-mentioned cast aluminum alloy in the manufacture of automotive parts.

[0023] The technical solution of the present invention has the following advantages compared with the prior art:

[0024] This invention relates to a cast aluminum alloy and its preparation method. By controlling the alloy composition and proportion, as well as the temperature and time of heat treatment during the preparation process, the volume fraction and size of the eutectic Si phase, and the volume fraction of the Al2Cu phase and Al5Cu2Mg8Si6 phase are adjusted, thereby simultaneously improving the strength, toughness and corrosion resistance of the Al-Cu alloy. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the alloy structure of Embodiment 1 of the present invention;

[0026] Figure 2 This is a schematic diagram of the alloy structure of Embodiment 2 of the present invention;

[0027] Figure 3 This is a schematic diagram of the alloy structure of Embodiment 3 of the present invention;

[0028] Figure 4 This is a schematic diagram of the alloy structure in Embodiment 4 of the present invention;

[0029] Figure 5 This is a schematic diagram of the alloy structure of Embodiment 5 of the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0031] Example 1:

[0032] This embodiment discloses a cast aluminum alloy and its preparation method, which has high strength and high toughness, while also improving fluidity and corrosion resistance. The composition and weight percentage of the aluminum alloy are as follows: Cu 4%, Si 0.2%, Mg 0.1%, Zr 0.1%, Cr 0.01%, Sc 0.01%, Zn 0.01%, Fe 0.1%, with the remainder being Al and unavoidable impurity elements.

[0033] The preparation method of the high-strength and high-toughness cast aluminum alloy based on the above composition in this embodiment includes the following steps:

[0034] (1) Add pure Al, pure Cu, Al-20Si master alloy, pure Mg, Al-5Zr master alloy, Al-10Cr master alloy, Al-5Sc master alloy, Al-10Fe master alloy, pure Zn, Al-50Sn and Al-10Mn master alloy to the above-mentioned aluminum alloys, melt the alloys at 750℃ for 30min, and obtain ingots by gravity casting in a metal mold. The cooling rate during the solidification process of the alloy is 30℃ / min.

[0035] (2) The ingot from step (1) is subjected to solution treatment and aging treatment:

[0036] First, the aluminum alloy ingot is placed in a heat treatment furnace, and the ingot is heated from room temperature (25°C) to 490°C at a rate of 180°C per hour and held for 8 hours. Then, it is heated to 515°C and held for 5 hours. After completion, it is subjected to water quenching.

[0037] The alloy ingot after solution treatment was held at 150℃ for 10 hours to obtain a high-strength and high-toughness cast aluminum alloy.

[0038] The alloy microstructure obtained in this embodiment is as follows: Figure 1 As shown, microscopic observation under a scanning electron microscope revealed that the volume fraction of the Al2Cu phase in the cast aluminum alloy was 0.1%, the volume fraction of the Al5Cu2Mg8Si6 phase was 0.1%, and the volume fraction of the eutectic Si was 0.01%. In the non-heat-treated state, the eutectic Si had a fibrous morphology, and the diameter of a single eutectic Si fiber was less than 3 μm.

[0039] According to the tensile property test (test standard GB / T6397-1985), the yield strength of the cast aluminum alloy is 480MPa, the tensile strength is 520MPa, and the elongation is 10%.

[0040] Example 2:

[0041] This embodiment discloses a cast aluminum alloy and its preparation method, which has high strength and high toughness, while also improving fluidity and corrosion resistance. The composition and weight percentage of the aluminum alloy are as follows: Cu 4.5%, Si 0.25%, Mg 0.2%, Zr 0.2%, Cr 0.1%, Sc 0.1%, Zn 0.3%, Fe 0.2%, Mn 0.01%, with the remainder being Al and unavoidable impurity elements.

[0042] The preparation method of the high-strength and high-toughness cast aluminum alloy based on the above composition in this embodiment includes the following steps:

[0043] (1) Add pure Al, pure Cu, Al-20Si master alloy, pure Mg, Al-5Zr master alloy, Al-10Cr master alloy, Al-5Sc master alloy, Al-10Fe master alloy, pure Zn, Al-50Sn and Al-10Mn master alloy to the above-mentioned aluminum alloys, melt the alloys at 760℃ for 35min, and obtain ingots by high pressure casting. The cooling rate of the alloy solidification process is 400℃ / min.

[0044] (2) The ingot from step (1) is subjected to solution treatment and aging treatment:

[0045] First, the aluminum alloy ingot is placed in a heat treatment furnace, and the ingot is heated from room temperature (25°C) to 494°C at a rate of 180°C per hour and held for 10 hours. Then, it is heated to 520°C and held for 6 hours. After completion, it is subjected to water quenching.

[0046] The alloy ingot after solution treatment was held at 160℃ for 10 hours to obtain a high-strength and high-toughness cast aluminum alloy.

[0047] The alloy microstructure obtained in this embodiment is as follows: Figure 2 As shown, microscopic observation under a scanning electron microscope revealed that the volume fraction of the Al2Cu phase in the cast aluminum alloy was 0.5%, the volume fraction of the Al5Cu2Mg8Si6 phase was 0.4%, and the volume fraction of the eutectic Si was 0.15%. In the non-heat-treated state, the eutectic Si had a fibrous morphology, and the diameter of a single eutectic Si fiber was less than 3 μm.

[0048] According to the tensile property test (test standard GB / T6397-1985), the yield strength of the cast aluminum alloy is 496MPa, the tensile strength is 573MPa, and the elongation is 14%.

[0049] Example 3:

[0050] This embodiment discloses a cast aluminum alloy and its preparation method, which has high strength and high toughness, while also improving fluidity and corrosion resistance. The composition and weight percentage of the aluminum alloy are as follows: Cu 6%, Si 0.3%, Mg 0.3%, Zr 0.3%, Cr 0.2%, Sc 0.2%, Zn 0.5%, Fe 0.3%, Mn 0.03%, with the remainder being Al and unavoidable impurity elements.

[0051] The preparation method of the high-strength and high-toughness cast aluminum alloy based on the above composition in this embodiment includes the following steps:

[0052] (1) Add pure Al, pure Cu, Al-20Si master alloy, pure Mg, Al-5Zr master alloy, Al-10Cr master alloy, Al-5Sc master alloy, Al-10Fe master alloy, pure Zn, Al-50Sn and Al-10Mn master alloy to the above-mentioned aluminum alloys, melt the alloys at 770℃ for 25min, and obtain ingots by extrusion casting. The cooling rate of the alloy solidification process is 280℃ / min.

[0053] (2) The ingot from step (1) is subjected to solution treatment and aging treatment:

[0054] First, the aluminum alloy ingot is placed in a heat treatment furnace, and the ingot is heated from room temperature (25°C) to 500°C at a rate of 180°C per hour and held for 10 hours. Then, it is heated to 525°C and held for 7 hours. After completion, it is subjected to water quenching.

[0055] The alloy ingot after solution treatment was held at 170℃ for 12 hours to obtain a high-strength and high-toughness cast aluminum alloy.

[0056] The alloy microstructure obtained in this embodiment is as follows: Figure 3 As shown, microscopic observation under a scanning electron microscope revealed that the volume fraction of the Al2Cu phase in the cast aluminum alloy was 1%, the volume fraction of the Al5Cu2Mg8Si6 phase was 0.8%, and the volume fraction of the eutectic Si was 0.1%. In the non-heat-treated state, the eutectic Si had a fibrous morphology, and the diameter of a single eutectic Si fiber was less than 3 μm.

[0057] According to the tensile property test (test standard GB / T6397-1985), the yield strength of the cast aluminum alloy is 500MPa, the tensile strength is 580MPa, and the elongation is 15%.

[0058] Example 4:

[0059] This embodiment discloses a cast aluminum alloy and its preparation method, which has high strength and high toughness, while also improving fluidity and corrosion resistance. The composition and weight percentage of the aluminum alloy are as follows: Cu 6.5%, Si 0.5%, Mg 0.4%, Zr 0.4%, Cr 0.24%, Sc 0.26%, Zn 0.8%, Fe 0.4%, Mn 0.06%, with the remainder being Al and unavoidable impurity elements.

[0060] The preparation method of the high-strength and high-toughness cast aluminum alloy based on the above composition in this embodiment includes the following steps:

[0061] (1) Add pure Al, pure Cu, Al-20Si master alloy, pure Mg, Al-5Zr master alloy, Al-10Cr master alloy, Al-5Sc master alloy, Al-10Fe master alloy, pure Zn, Al-50Sn and Al-10Mn master alloy to the above-mentioned aluminum alloys, melt the alloys at 740℃ for 50 min, and obtain ingots by low-pressure casting. The cooling rate of the alloy solidification process is 300℃ / min.

[0062] (2) The ingot from step (1) is subjected to solution treatment and aging treatment:

[0063] First, the aluminum alloy ingot is placed in a heat treatment furnace, and the ingot is heated from room temperature (25°C) to 505°C at a rate of 180°C per hour and held for 12 hours. Then, it is heated to 528°C and held for 8 hours. After completion, it is subjected to water quenching.

[0064] The alloy ingot after solution treatment was held at 175℃ for 10 hours to obtain a high-strength and high-toughness cast aluminum alloy.

[0065] The alloy microstructure obtained in this embodiment is as follows: Figure 4 As shown, microscopic observation under a scanning electron microscope revealed that the volume fraction of the Al2Cu phase in the cast aluminum alloy was 1.5%, the volume fraction of the Al5Cu2Mg8Si6 phase was 1%, and the volume fraction of the eutectic Si was 0.15%. In the non-heat-treated state, the eutectic Si had a fibrous morphology, and the diameter of a single eutectic Si fiber was less than 3 μm.

[0066] According to the tensile property test (test standard GB / T6397-1985), the yield strength of the cast aluminum alloy is 491 MPa, the tensile strength is 569 MPa, and the elongation is 12%.

[0067] Example 5:

[0068] This embodiment discloses a cast aluminum alloy and its preparation method, which has high strength and high toughness, while also improving fluidity and corrosion resistance. The composition and weight percentage of the aluminum alloy are as follows: Cu 7%, Si 0.7%, Mg 0.5%, Zr 0.5%, Cr 0.03%, Sc 0.3%, Zn 1%, Fe 0.5%, with the remainder being Al and unavoidable impurity elements.

[0069] The preparation method of the high-strength and high-toughness cast aluminum alloy based on the above composition in this embodiment includes the following steps:

[0070] (1) Add pure Al, pure Cu, Al-20Si master alloy, pure Mg, Al-5Zr master alloy, Al-10Cr master alloy, Al-5Sc master alloy, Al-10Fe master alloy, pure Zn, Al-50Sn and Al-10Mn master alloy to the above-mentioned aluminum alloys, melt the alloys at 745℃ for 60min, and obtain ingots by differential pressure casting. The cooling rate of the alloy solidification process is 120℃ / min.

[0071] (2) The ingot from step (1) is subjected to solution treatment and aging treatment:

[0072] First, the aluminum alloy ingot is placed in a heat treatment furnace, and the ingot is heated from room temperature (25°C) to 510°C at a rate of 180°C per hour and held for 14 hours. Then, it is heated to 530°C and held for 9 hours. After completion, it is subjected to water quenching.

[0073] The alloy ingot after solution treatment was held at 180℃ for 15 hours to obtain a high-strength and high-toughness cast aluminum alloy.

[0074] The alloy microstructure obtained in this embodiment is as follows: Figure 5 As shown, microscopic observation under a scanning electron microscope revealed that the volume fraction of the Al2Cu phase in the cast aluminum alloy was 1.8%, the volume fraction of the Al5Cu2Mg8Si6 phase was 1.2%, and the volume fraction of the eutectic Si was 0.2%. In the non-heat-treated state, the eutectic Si had a fibrous morphology, and the diameter of a single eutectic Si fiber was less than 3 μm.

[0075] According to the tensile property test (test standard GB / T6397-1985), the yield strength of the cast aluminum alloy is 492MPa, the tensile strength is 564MPa, and the elongation is 13%.

[0076] The technical content and features of the present invention have been disclosed above. However, those skilled in the art may still make various substitutions and modifications that do not depart from the spirit of the present invention based on the teachings and disclosures of the present invention. Therefore, the scope of protection of the present invention should not be limited to the content disclosed in the embodiments, but should include various substitutions and modifications that do not depart from the present invention, and should be covered by the claims of this patent application.

Claims

1. A cast aluminum alloy, characterized in that, By weight, the cast aluminum alloy is composed of the following elements: Cu 4-7%, Si 0.2-0.7%, Mg 0.1-0.5%, Zr 0.1-0.5%, Cr 0.01-0.3%, Sc 0.01-0.3%, Zn 0.01-1%, Fe 0.1-0.5%, Sn 0.01-0.1%, Mn≤0.1%, with the remainder being Al and unavoidable impurity elements; The cast aluminum alloy comprises eutectic Si, α-Fe, Al5Cu2Mg8Si6, Mg2Si, Al2Cu and AlSn phases, wherein the volume fraction of the Al2Cu phase is 0.1-1.8%, the volume fraction of the Al5Cu2Mg8Si6 phase is 0.1-1.2%, and the volume fraction of the eutectic Si is 0.01-0.2%. In the non-heat-treated state, the eutectic Si has a fibrous morphology, and the diameter of a single eutectic Si fiber is less than 3 μm.

2. The cast aluminum alloy as described in claim 1, characterized in that, The yield strength of the cast aluminum alloy is 480-500 MPa.

3. The cast aluminum alloy as described in claim 1, characterized in that, The tensile strength of the cast aluminum alloy is 520-580 MPa.

4. The cast aluminum alloy as described in claim 1, characterized in that, The elongation of the cast aluminum alloy is 10-15%.

5. A method for preparing the cast aluminum alloy according to any one of claims 1-4, characterized in that, Includes the following steps: S11: Aluminum alloy ingots are obtained by batching, smelting, and casting using pure Al, pure Cu, pure Mg, and intermediate alloys as raw materials; By weight, the aluminum alloy ingot is composed of the following elements: Cu 4-7%, Si 0.2-0.7%, Mg 0.1-0.5%, Zr 0.1-0.5%, Cr 0.01-0.3%, Sc 0.01-0.3%, Zn 0.01-1%, Fe 0.1%-0.5%, Sn 0.01%-0.1%, Mn≤0.1%, with the remainder being Al and unavoidable impurity elements; S12: The aluminum alloy ingot is subjected to solution treatment and aging treatment to obtain the cast aluminum alloy; the solution treatment steps are as follows: S21: Heat the aluminum alloy ingot to 490-510℃ and hold for 8-14 hours; S22: After the aluminum alloy ingot has been heat-preserved in S21, heat it to 515-530℃ and hold it for 5-9 hours before water quenching.

6. The preparation method according to claim 5, characterized in that, The master alloys include Al-20Si master alloy, Al-5Zr master alloy, Al-10Cr master alloy, Al-5Sc master alloy, Al-10Fe master alloy, Al-50Sn master alloy and Al-10Mn master alloy.

7. The preparation method according to claim 5, characterized in that, In step S11, the casting method is selected from gravity casting, high pressure casting, squeeze casting, low pressure casting or differential pressure casting.

8. The preparation method according to claim 5, characterized in that, In step S21, the heating rate is 40-110°C per hour.

9. The preparation method according to claim 5, characterized in that, In step S12, the aging treatment method is to keep the solution-treated aluminum alloy ingot at 150-180℃ for 10-15 hours.

10. The application of the cast aluminum alloy according to any one of claims 1-4 in the manufacture of automotive parts.

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