Cast aluminum alloy and preparation method therefor

Abstract

The present invention belongs to the field of aluminum alloys, and particularly relates to a cast aluminum alloy and a preparation method therefor. The aluminum alloy comprises the following components: 4-8% of Mg, 1-6% of Si, 0.1-0.5% of Fe, 0.5-3% of Cu, 0.5-1.5% of Zn, 0.1-0.5% of Mn, 0.01-0.1% of Mo, 0.01-0.1% of V, 0.01-0.03% of Sr, and the balance of Al and inevitable impurity elements. The cast aluminum alloy comprises Si, AlMg, α-Fe, Al5Cu2Mg8Si6, Mg2Si and Al2Cu phases. The preparation method for the aluminum alloy comprises casting forming and a heat treatment. The cast aluminum alloy has a yield strength of 270-320 MPa, a tensile strength of 330-380 MPa, and an elongation of 6-10%. The cast aluminum alloy and the preparation method of the present invention achieve the synchronous improvement of the formability, strength, toughness and corrosion resistance of an Al-Mg alloy.

Description

A cast aluminum alloy and its preparation method 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 requirements of modern automobiles, making it urgent to improve the comprehensive mechanical properties of cast aluminum alloys. Al-Mg alloys, due to their superior mechanical properties compared to Al-Si casting alloys, are ideal materials to replace Al-Si alloys in the manufacture of automobile bodies and components. However, the low fluidity of Al-Mg alloys and their inability to be heat-treated for strengthening limit their application range.

[0003] Chinese invention patent CN 118531268A discloses a high-strength and high-toughness cast Al-Mg alloy and its preparation method. This invention uses a squeeze casting method to prepare the alloy and utilizes the residual heat from pressure casting for quenching, thereby improving the alloy's strength and toughness. However, this invention is only applicable to squeeze casting, limiting the alloy's forming methods. Furthermore, the alloy cannot be strengthened by heat treatment, resulting in limited strength improvement; the yield strength of the alloy does not exceed 165 MPa, significantly restricting its application range.

[0004] Chinese invention patent CN110603341A discloses a high-strength and tough cast Al-Mg alloy and its preparation method. It effectively improves the strength and toughness of the Al-Mg alloy by adding Zr, Sc, Hf, V and Cr elements. However, the addition of the above elements will undoubtedly increase the production cost of parts. At the same time, the alloy cannot be strengthened by heat treatment, and the strength improvement effect is limited. 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 some extent, but they do not change the characteristic that the alloys cannot be strengthened by heat treatment. Significantly improving the strength of cast aluminum alloys is of great importance to enhancing the safety of automotive parts.

[0006] To address the aforementioned technical problems, this application provides the following technical solution: This invention provides a cast aluminum alloy, wherein the volume fraction of eutectic Si is 0.01-2.2%; in the non-heat-treated state, the eutectic Si has a fibrous morphology, with the diameter of a single eutectic Si fiber being less than 3 μm; the volume fraction of the AlMg phase is 3-18%; the volume fraction of the Fe-containing α-Al(FeM)Si phase is 0.1-2.3%, with a size of 200-500 nm; wherein M is selected from one or more of Mn, Mo, and V; the volume fraction of the Al5Cu2Mg8Si6 phase is 0.1-5.8%, with a size not exceeding 10 μm; the mass ratio of Mg to Si is greater than 1.3, the volume fraction of the Mg2Si phase is 3-14%, and the volume fraction of the Al2Cu phase is 0.1-1.8%.

[0007] Preferably, by weight fraction, the aluminum alloy comprises 4-8% Mg, 1-6% Si, 0.1-0.5% Fe, 0.5%-3% Cu, 0.5-1.5% Zn, 0.01-0.5% Mn, 0.01-0.1% Mo, 0.01-0.1% V, 0.01-0.03% Sr, with the remainder being Al and unavoidable impurity elements.

[0008] The present invention also provides a method for preparing the above-mentioned cast aluminum alloy, comprising the following steps: S11: using pure Al, pure Mg, Al-20Si, Al-10Fe, pure Cu, pure Zn, Al-10Mn master alloy, Al-5Mo master alloy, Al-5V master alloy and Al-10Sr master alloy as raw materials for batching and smelting to obtain an aluminum alloy ingot; by weight fraction, the composition of the aluminum alloy ingot includes Mg 4-8%, Si 1-6%, Fe 0.1-0.5%, Cu 0.5%-3%, Zn 0.5-1.5%, Mn 0.01-0.5%, Mo 0.01-0.1%, V 0.01-0.1%, Sr 0.01-0.03%, with the remainder being Al and unavoidable impurity elements; S12: subjecting the aluminum alloy ingot to solution treatment and aging treatment to obtain the cast aluminum alloy.

[0009] Preferably, the casting is carried out after melting, and the casting method is selected from gravity casting, high pressure casting, squeeze casting, low pressure casting or differential pressure casting.

[0010] Preferably, in step S12, the solution treatment includes the following steps: S21: placing the aluminum alloy ingot in a heat treatment furnace and heating it to 480-500℃ and holding it for 6-10 hours; S22: heating it to 510-530℃ and holding it for 1-8 hours; S23: performing water quenching treatment to complete the solution treatment step.

[0011] Furthermore, in step S21, the temperature is increased at a rate of 40-110°C per hour.

[0012] Preferably, in step S12, the yield strength of the aluminum alloy ingot after solution treatment and aging is 270-320 MPa.

[0013] Preferably, in step S12, the tensile strength of the aluminum alloy ingot after solution treatment and aging treatment is 330-380 MPa.

[0014] Preferably, in step S12, the elongation of the aluminum alloy ingot after solution treatment and aging is 6% to 10%.

[0015] Preferably, in step S12, the aging treatment includes the following steps: aging the solution-treated alloy ingot at 160–190°C for 15–22 hours to obtain the cast aluminum alloy.

[0016] Compared with the prior art, the technical solution of the present invention has the following advantages: The present invention is a casting 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 of eutectic Si, the Fe-containing phase of α-Al(FeM)Si (where M is one or more of Mn, Mo, and V), the volume fraction and size of Al5Cu2Mg8Si6 phase and Al2Cu phase are controlled, thereby simultaneously improving the strength, toughness, fluidity and corrosion resistance of Al-Mg alloy. Attached Figure Description

[0017] Figure 1 is a schematic diagram of the alloy structure of Embodiment 1 of the present invention; Figure 2 is a schematic diagram of the alloy structure of Embodiment 2 of the present invention; Figure 3 is a schematic diagram of the alloy structure of Embodiment 3 of the present invention; Figure 4 is a schematic diagram of the alloy structure of Embodiment 4 of the present invention; Figure 5 is a schematic diagram of the alloy structure of Embodiment 5 of the present invention. Detailed Implementation

[0018] 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. Embodiment 1

[0019] 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: Mg 4%, Si 1%, Fe 0.1%, Cu 0.5%, Zn 0.5%, Mn 0.1%, Mo 0.01%, V 0.01%, Sr 0.01%, with the remainder being Al and unavoidable impurity elements.

[0020] The preparation method of the high-toughness cast aluminum alloy based on the above composition in this embodiment includes the following steps: (1) The aluminum alloy with the above composition is batched, melted, and ingots are obtained by gravity casting; (2) The ingot in step (1) is subjected to solution treatment and aging treatment: First, the aluminum alloy ingot is placed in a heat treatment furnace, and the ingot is heated from room temperature (25°C) to 480°C at 40°C per hour and held for 6 hours, and then heated to 510°C and held for 1 hour. After completion, water quenching treatment is performed; The alloy ingot after solution treatment is held at 160°C for 15 hours to finally obtain the high-toughness cast aluminum alloy.

[0021] In this embodiment, the alloy contains 4% Mg and 4% Si by mass. The microstructure of the alloy obtained in this embodiment is shown in Figure 1. Observation of the microstructure under a scanning electron microscope revealed that the Fe-containing phase in the non-heat-treated state of the cast aluminum alloy includes α-Al(FeMn)Si, α-Al(FeMo)Si, and α-Al(FeV)Si, with a volume fraction of Fe ranging from 0.3% and a size of approximately 200 nm. The volume fraction of the Mg2Si phase is 3.1%, the volume fraction of the Al2Cu phase is 0.18%, and the volume fraction of the AlMg phase is 6%.

[0022] Tensile property tests (test standard GB / T6397-1985) showed that the cast aluminum alloy had a yield strength of 272 MPa, a tensile strength of 336 MPa, and an elongation of 6.2%. Example 2

[0023] 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: Mg 5%, Si 2.5%, Fe 0.2%, Cu 1%, Zn 0.7%, Mn 0.2%, Mo 0.03%, V 0.03%, Sr 0.01%, with the remainder being Al and unavoidable impurity elements.

[0024] The preparation method of the high-toughness cast aluminum alloy based on the above composition in this embodiment includes the following steps: (1) The aluminum alloy with the above composition is batched, melted, and ingots are obtained by gravity casting; (2) The ingots in step (1) are subjected to solution treatment and aging treatment: First, the aluminum alloy ingots are placed in a heat treatment furnace, and the ingots are heated from room temperature to 485°C at 60°C per hour and held for 7 hours, and then heated to 515°C and held for 3 hours. After completion, water quenching treatment is performed; The alloy ingots after solution treatment are held at 170°C for 16 hours to finally obtain the high-toughness cast aluminum alloy.

[0025] In this embodiment, the alloy contains 2% Mg and 2% Si by mass. The microstructure of the alloy obtained in this embodiment is shown in Figure 2. Observation of the microstructure under a scanning electron microscope revealed that the Fe-containing phase in the non-heat-treated state of the cast aluminum alloy includes α-Al(FeMn)Si, α-Al(FeMo)Si, and α-Al(FeV)Si, with a volume fraction of Fe ranging from 0.5% and a size of approximately 270 nm. The volume fraction of the Al5Cu2Mg8Si6 phase ranges from 0.43% and the size is approximately 10 μm. The volume fraction of the Mg2Si phase is 7%, the volume fraction of the Al2Cu phase is 0.1%, and the volume fraction of the AlMg phase is 18%.

[0026] Tensile property tests (test standard GB / T6397-1985) showed that the cast aluminum alloy had a yield strength of 287 MPa, a tensile strength of 347 MPa, and an elongation of 7.4%. Example 3

[0027] 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: Mg 6.5%, Si 3%, Fe 0.3%, Cu 2%, Zn 1%, Mn 0.3%, Mo 0.05%, V 0.05%, Sr 0.02%, with the remainder being Al and unavoidable impurity elements.

[0028] The preparation method of the cast aluminum alloy based on the above composition in this embodiment includes the following steps: (1) The aluminum alloy is batched, melted, and ingots are obtained by extrusion casting; (2) The ingots in step (1) are subjected to solution treatment and aging treatment: First, the aluminum alloy ingots are placed in a heat treatment furnace, and the ingots are heated from room temperature to 490°C at 80°C per hour and held for 8 hours, and then heated to 520°C and held for 5 hours. After completion, water quenching treatment is performed; The alloy ingots after solution treatment are held at 175°C for 19 hours to finally obtain high-toughness cast aluminum alloys.

[0029] In this embodiment, the alloy contains 2.2% Mg and Si by mass. The microstructure of the alloy obtained in this embodiment is shown in Figure 3. Observation of the microstructure under a scanning electron microscope revealed that the Fe-containing phase in the non-heat-treated state of the cast aluminum alloy includes α-Al(FeMn)Si, α-Al(FeMo)Si, and α-Al(FeV)Si, with a volume fraction of Fe ranging from 1.1% and a size of approximately 350 nm. The volume fraction of the Al5Cu2Mg8Si6 phase ranges from 0.8% and the size is approximately 8 μm. The volume fraction of the Mg2Si phase is 9.7%, the volume fraction of the Al2Cu phase is 0.8%, and the volume fraction of the AlMg phase is 12%.

[0030] Tensile property tests (test standard GB / T6397-1985) showed that the cast aluminum alloy had a yield strength of 299 MPa, a tensile strength of 365 MPa, and an elongation of 8.7%. Example 4

[0031] 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: Mg 7%, Si 5%, Fe 0.4%, Cu 2.5%, Zn 1.3%, Mn 0.4%, Mo 0.07%, V 0.07%, Sr 0.03%, with the remainder being Al and unavoidable impurity elements.

[0032] The preparation method of the high-toughness cast aluminum alloy based on the above composition in this embodiment includes the following steps: (1) The aluminum alloy with the above composition is batched, melted, and ingots are obtained by gravity casting; (2) The ingots in step (1) are subjected to solution treatment and aging treatment: First, the aluminum alloy ingots are placed in a heat treatment furnace, and the ingots are heated from room temperature to 495°C at 100°C per hour and held for 9 hours, and then heated to 525°C and held for 7 hours. After completion, water quenching treatment is performed; The alloy ingots after solution treatment are held at 180°C for 21 hours to finally obtain the high-toughness cast aluminum alloy.

[0033] In this embodiment, the mass percentage of Mg to Si in the alloy is 1.4. The microstructure of the alloy obtained in this embodiment is shown in Figure 4. Observation of the microstructure under a scanning electron microscope revealed that the volume fraction of eutectic Si in the matrix of the cast aluminum alloy in the non-heat-treated state ranges from 2.2%, with a fibrous morphology. The Fe-containing phases include α-Al(FeMn)Si, α-Al(FeMo)Si, and α-Al(FeV)Si, with a volume fraction of Fe ranging from 1.6% and a size of approximately 400 nm. The volume fraction of the Al5Cu2Mg8Si6 phase ranges from 5.9%, with a size of approximately 10 μm. The volume fraction of the Mg2Si phase is 10%, and the volume fraction of the Al2Cu phase is 0.13%.

[0034] Tensile property tests (test standard GB / T6397-1985) showed that the cast aluminum alloy had a yield strength of 310 MPa, a tensile strength of 370 MPa, and an elongation of 9.2%. Example 5

[0035] 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: Mg 8%, Si 6%, Fe 0.5%, Cu 3%, Zn 1.5%, Mn 0.5%, Mo 0.1%, V 0.1%, Sr 0.03%, with the remainder being Al and unavoidable impurity elements.

[0036] The preparation method of the high-toughness cast aluminum alloy based on the above composition in this embodiment includes the following steps: (1) The aluminum alloy is batched, melted, and ingots are obtained by high pressure; (2) The ingots in step (1) are subjected to solution treatment and aging treatment: The aluminum alloy ingots are placed in a heat treatment furnace, and the ingots are heated from room temperature to 500°C at 110°C per hour and held for 10 hours, and then heated to 530°C and held for 8 hours. After completion, water quenching treatment is performed; The alloy ingots after solution treatment are held at 190°C for 22 hours to finally obtain the high-toughness cast aluminum alloy.

[0037] In this embodiment, the mass percentage of Mg to Si in the alloy is 1.3. The microstructure of the alloy obtained in this embodiment is shown in Figure 5. Observation of the microstructure under a scanning electron microscope revealed that the volume fraction of eutectic Si in the matrix of the cast aluminum alloy in the non-heat-treated state ranges from 0.8%, with a fibrous morphology. The Fe-containing phases include α-Al(FeMn)Si, α-Al(FeMo)Si, and α-Al(FeV)Si, with a volume fraction of Fe ranging from 2.3% and a size of approximately 500 nm. The volume fraction of the Al5Cu2Mg8Si6 phase ranges from 2.2%, with a size of approximately 6 μm. The volume fraction of the Mg2Si phase is 14%, the volume fraction of the Al2Cu phase is 1.8%, and the volume fraction of the AlMg phase is 3%.

[0038] According to the tensile property test (test standard GB / T6397-1985), the yield strength of the cast aluminum alloy is 323 MPa, the tensile strength is 382 MPa, and the elongation is 10.1%.

[0039] 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 by, In the cast aluminum alloy The volume fraction of eutectic Si is 0.01-2.2%; 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; the volume fraction of AlMg phase is 3-18%. The α-Fe phase is the α-Al(FeM)Si phase, with a volume fraction of 0.1-2.3% and a size of 200-500 nm; wherein M is selected from one or more of Mn, Mo and V; the Al5Cu2Mg8Si6 phase has a volume fraction of 0.1-5.8% and a size not greater than 10 μm; The mass ratio of Mg to Si is greater than 1.3, the volume fraction of the Mg2Si phase is 3-14%, and the volume fraction of the Al2Cu phase is 0.1-1.8%.

2. The cast aluminum alloy of claim 1, wherein, The aluminum alloy comprises, by weight fraction, 4-8% Mg, 1-6% Si, 0.1-0.5% Fe, 0.5%-3% Cu, 0.5-1.5% Zn, 0.01-0.5% Mn, 0.01-0.1% Mo, 0.01-0.1% V, 0.01-0.03% Sr, with the remainder being Al and unavoidable impurity elements.

3. A method of producing the cast aluminum alloy according to claim 2, characterized by, Includes the following steps: S11: Aluminum alloy ingots are prepared by batching and smelting pure Al, pure Mg, Al-20Si, Al-10Fe, pure Cu, pure Zn, Al-10Mn master alloy, Al-5Mo master alloy, Al-5V master alloy, and Al-10Sr master alloy. By weight fraction, the composition of the aluminum alloy ingot includes Mg 4-8%, Si 1-6%, Fe 0.1-0.5%, Cu 0.5%-3%, Zn 0.5-1.5%, Mn 0.01-0.5%, Mo 0.01-0.1%, V 0.01-0.1%, Sr 0.01-0.03%, 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.

4. The production method according to claim 3, wherein After melting, casting is carried out, and the casting method is selected from gravity casting, high pressure casting, squeeze casting, low pressure casting or differential pressure casting.

5. The production method according to claim 3, wherein In step S12, the solution treatment includes the following steps: S21: Place the aluminum alloy ingot in a heat treatment furnace and heat it to 480-500℃ for 6-10 hours; S22: Heat to 510-530℃ and hold for 1-8 hours; S23: Perform water quenching to complete the solution treatment step.

6. The production method according to claim 5, wherein In step S21, the temperature is increased at a rate of 40-110°C per hour.

7. The production method according to claim 3, wherein In step S12, the yield strength of the cast aluminum alloy is 270-320 MPa.

8. The production method according to claim 3, wherein In step S12, the tensile strength of the cast aluminum alloy is 330-380 MPa.

9. The production method according to claim 3, wherein In step S12, the elongation of the cast aluminum alloy is 6% to 10%.

10. The production method according to claim 3, wherein In step S12, the timeliness processing includes the following steps: The alloy ingot after solution treatment is held at 160–190°C for 15–22 hours to obtain the cast aluminum alloy.

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