A cast aluminum alloy and a method of making the same

Abstract

The application discloses a kind of cast aluminum alloy and its preparation method, belong to cast aluminum alloy field.The secondary dendrite spacing of the aluminum alloy is reduced in the application.The cast aluminum alloy mass percentage provided by the application includes: 6.2-9.9%Si;0.2-0.6%Mg;2.6-4.9%Cu;0.006-0.18%Mn;0.01-0.2%Zr;0.02-0.2%Ti;0.0-0.12%Sr;0.0-0.15%La;0.0-0.15%Ce;0.0-0.4%Y;0.0-0.4%Gd;0.0-0.25%Pr;balance Al and unavoidable impurities;Total amount of rare earth elements RE≤0.9%.The aluminum alloy prepared by the application has higher strength and good casting process, can further reduce the weight of automobile engine cylinder, meet the demand of automobile light weight.

Description

Technical Field

[0001] This invention relates to a cast aluminum alloy and its preparation method, belonging to the field of cast aluminum alloys. Background Technology

[0002] With the continuous upgrading of the automotive industry, traditional fuel vehicles are facing increasing competitive pressure, and people's requirements for vehicle performance and energy consumption are also rising. As part of lightweighting, the use of cast aluminum alloy materials for engine blocks, with embedded cast iron cylinder liners, is becoming increasingly common. Because engine blocks must withstand thermal shock and thermal fatigue, the rigidity, coefficient of thermal expansion, and comprehensive mechanical properties of the block material are required to be high. At the same time, the structure of the engine block is relatively complex, and to achieve the requirements of thin-walled, lightweight, and precision castings, the casting performance of the alloy is also required to be high. Currently, the main aluminum alloy materials used for engine blocks are AlSi9Cu3, AlSi10Mg, and A380 alloys. These alloys contain a high Si content, giving the liquid metal good fluidity, which can be used to form large and complex thin-walled castings. Adding a certain amount of Cu and a small amount of Mg allows for age hardening treatment by forming precipitates such as AlMgSiCu and Mg2Si.

[0003] Experiments show that, even with similar main components, differences in the content of microalloying elements lead to variations in the alloy's microstructure, significantly affecting its performance. Secondary dendrite spacing is the most representative factor. Secondary dendrite spacing is related to factors such as the cooling rate during the solidification process of cast aluminum alloys, alloy composition, and solute diffusion coefficient. A higher cooling rate results in a smaller secondary dendrite spacing and better mechanical properties. Alloy composition also has a crucial impact on secondary dendrite spacing; a higher solute diffusion coefficient leads to poorer thermal stability of the precipitated phase and a greater likelihood of secondary dendrite coarsening. By reducing the secondary dendrite spacing of the alloy, new aluminum alloy materials with higher strength can be developed under the condition that the casting process remains essentially unchanged, and these materials can be used as next-generation engine block materials. Summary of the Invention

[0004] To further reduce the secondary dendrite spacing of aluminum alloys, this invention provides a cast aluminum alloy and its preparation method.

[0005] The technical solution of the present invention:

[0006] One objective of this invention is to provide a cast aluminum alloy comprising, by mass percentage: 6.2-9.9% Si; 0.2-0.6% Mg; 2.6-4.9% Cu; 0.006-0.18% Mn; 0.01-0.2% Zr; 0.02-0.2% Ti; 0.0-0.12% Sr; 0.0-0.15% La; 0.0-0.15% Ce; 0.0-0.4% Y; 0.0-0.4% Gd; 0.0-0.25% Pr; with the balance being Al and unavoidable impurities; and the total rare earth element content (RE) ≤ 0.9%.

[0007] Further specified, the cast aluminum alloy comprises, by mass percentage: 6.2% Si; 0.42% Mg; 3.2% Cu; 0.006% Mn; 0.01% Zr; 0.17% Ti; 0.082% Sr; 0.15% La; 0.01% Ce; 0.2% Pr, with the balance being Al and unavoidable impurities.

[0008] Further specified, the cast aluminum alloy comprises, by mass percentage: 9.5% Si; 0.43% Mg; 3.0% Cu; 0.14% Mn; 0.16% Zr; 0.055% Ti; 0.12% Sr; 0.13% La; 0.10% Ce; 0.01% Y; 0.2% Gd; 0.05% Pr; with the balance being Al and unavoidable impurities.

[0009] Further specifying, the cast aluminum alloy comprises, by mass percentage: 8.5% Si; 0.56% Mg; 3.8% Cu; 0.16% Mn; 0.12% Zr; 0.12% Ti; 0.063% Sr; 0.07% La; 0.12% Ce; 0.35% Y; 0.34% Gd; 0.06% Pr; with the balance being Al and unavoidable impurities.

[0010] A second objective of this invention is to provide a method for preparing the above-mentioned cast aluminum alloy, the method comprising the following steps:

[0011] (1) According to the aluminum alloy formula, AlSi20, metallic magnesium, AlCu50, AlMn10, AlTi10, AlSr10, AlZr5, AlLa20, AlCe10, AlY20, MgGd80, and MgPr20 are used as raw materials for batching.

[0012] (2) The raw materials in (1) are put into the smelting furnace in sequence for smelting, with metallic magnesium and raw materials containing rare earth elements being added last;

[0013] (3) The refining, slag removal, refining, casting, two-stage solution treatment and aging treatment are carried out in sequence.

[0014] Further specified, the melting temperature in (2) is 730-760℃.

[0015] Further specifying, (3) the refining process is: using argon gas with a purity of 99.9% to blow gas into the aluminum alloy liquid in the melting furnace for 5 minutes.

[0016] Further specifying, the casting temperature in (3) is 660-700℃.

[0017] Further specifying, (3) the two-stage solution treatment is: 500-510℃ for 3-6 hours; 520-530℃ for 6-10 hours.

[0018] Further specifying, (3) the aging treatment is to keep warm at 150-170℃ for 5-12 hours.

[0019] The third objective of this invention is to provide an application of the above-mentioned cast aluminum alloy, specifically for the manufacture of automobile engine cylinder blocks.

[0020] Beneficial effects:

[0021] This invention incorporates multiple rare earth elements, utilizing their interactions to enhance solute enrichment at the solid-liquid interface front, thereby promoting interface morphology instability, increasing grain boundary bifurcation probability, and reducing secondary dendrite spacing. Furthermore, the aluminum rare earth phase exhibits excellent thermal stability, preventing secondary dendrite coarsening during solidification, thus improving the alloy's mechanical properties.

[0022] The mechanical properties of the cast aluminum alloy provided by this invention can reach 350-450 MPa, which can meet the requirements of next-generation engine cylinder block materials. Attached Figure Description

[0023] Figure 1 An optical micrograph of the cast aluminum alloy prepared in Example 1;

[0024] Figure 2 An optical micrograph of the cast aluminum alloy prepared in Example 2;

[0025] Figure 3 An optical micrograph of the cast aluminum alloy prepared in Example 3;

[0026] Figure 4 An optical micrograph of the cast aluminum alloy prepared in Comparative Example 1.

[0027] Figure 5 Optical micrograph of the cast aluminum alloy prepared for Comparative Example 2. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0030] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0031] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0032] Example 1:

[0033] The cast aluminum alloy provided in this embodiment has the following elemental composition by mass percentage: 6.2% Si; 0.42% Mg; 3.2% Cu; 0.006% Mn; 0.01% Zr; 0.17% Ti; 0.082% Sr; 0.15% La; 0.01% Ce; 0.2% Pr, with the balance being Al and unavoidable impurities.

[0034] The preparation process of the above-mentioned cast aluminum alloy includes the following steps:

[0035] Step 1: Prepare the raw materials by calculating the mass of each raw material according to the element formula. The raw materials are AlSi20, metallic magnesium, AlCu50, AlMn10, AlTi10, AlSr10, AlZr5, AlLa20, AlCe10, AlY20, MgGd80, and MgPr20.

[0036] Step 2: Add the following ingredients in sequence to the melting furnace: AlSi20, metallic magnesium, AlCu50, AlMn10, AlTi10, AlSr10, AlZr5, AlLa20, AlCe10, AlY20, MgGd80, and MgPr20. Control the temperature of the molten aluminum at 730-760℃. Add magnesium and rare earth elements last, and add some rare earth elements as magnesium-rare earth intermediate alloys to reduce the loss of magnesium and rare earth elements.

[0037] Step 3: Refine and remove slag to obtain qualified components. Then, use 99.9% pure argon gas to blow gas into the aluminum alloy molten metal in the melting furnace for 5 minutes to refine it and reduce the gas content in the molten aluminum.

[0038] Step 4: Control the casting temperature between 660℃ and 700℃ and perform slow casting.

[0039] Step 5: Use a two-stage solution treatment at 500℃ for 6 hours and at 520℃ for 6 hours.

[0040] Step 6: After solution treatment, perform aging treatment within 12 hours. The aging temperature is 150℃ and the holding time is 12 hours.

[0041] Example 2:

[0042] The cast aluminum alloy provided in this embodiment has the following elemental composition by mass percentage: 9.5% Si; 0.43% Mg; 3.0% Cu; 0.14% Mn; 0.16% Zr; 0.055% Ti; 0.12% Sr; 0.13% La; 0.10% Ce; 0.01% Y; 0.2% Gd; 0.05% Pr; with the balance being Al and unavoidable impurities.

[0043] The preparation process of the above-mentioned cast aluminum alloy includes the following steps:

[0044] Step 1: Prepare the raw materials by calculating the mass of each raw material according to the element formula. The raw materials are AlSi20, metallic magnesium, AlCu50, AlMn10, AlTi10, AlSr10, AlZr5, AlLa20, AlCe10, AlY20, MgGd80, and MgPr20.

[0045] Step 2: Add the following ingredients in sequence to the melting furnace: AlSi20, metallic magnesium, AlCu50, AlMn10, AlTi10, AlSr10, AlZr5, AlLa20, AlCe10, AlY20, MgGd80, and MgPr20. Control the temperature of the molten aluminum at 730-760℃. Add magnesium and rare earth elements last, and add some rare earth elements as magnesium-rare earth intermediate alloys to reduce the loss of magnesium and rare earth elements.

[0046] Step 3: Refine and remove slag to obtain qualified components. Then, use 99.9% pure argon gas to blow gas into the aluminum alloy molten metal in the melting furnace for 5 minutes to refine it and reduce the gas content in the molten aluminum.

[0047] Step 4: Control the casting temperature between 660℃ and 700℃ and perform slow casting.

[0048] Step 5: Use a two-stage solution treatment at 510℃ for 4 hours and 525℃ for 8 hours.

[0049] Step 6: After solution treatment, perform aging treatment within 12 hours. The aging temperature is 170℃ and the holding time is 12 hours.

[0050] Example 3:

[0051] The cast aluminum alloy provided in this embodiment has the following elemental composition by mass percentage: 8.5% Si; 0.56% Mg; 3.8% Cu; 0.16% Mn; 0.12% Zr; 0.12% Ti; 0.063% Sr; 0.07% La; 0.12% Ce; 0.35% Y; 0.34% Gd; 0.06% Pr; with the balance being Al and unavoidable impurities.

[0052] The preparation process of the above-mentioned cast aluminum alloy includes the following steps:

[0053] Step 1: Prepare the raw materials by calculating the mass of each raw material according to the element formula. The raw materials are AlSi20, metallic magnesium, AlCu50, AlMn10, AlTi10, AlSr10, AlZr5, AlLa20, AlCe10, AlY20, MgGd80, and MgPr20.

[0054] Step 2: Add the following ingredients in sequence to the melting furnace: AlSi20, metallic magnesium, AlCu50, AlMn10, AlTi10, AlSr10, AlZr5, AlLa20, AlCe10, AlY20, MgGd80, and MgPr20. Control the temperature of the molten aluminum at 730-760℃. Add magnesium and rare earth elements last, and add some rare earth elements as magnesium-rare earth intermediate alloys to reduce the loss of magnesium and rare earth elements.

[0055] Step 3: Refine and remove slag to obtain qualified components. Then, use 99.9% pure argon gas to blow gas into the aluminum alloy molten metal in the melting furnace for 5 minutes to refine it and reduce the gas content in the molten aluminum.

[0056] Step 4: Control the casting temperature between 660℃ and 700℃ and perform slow casting.

[0057] Step 5: Use a two-stage solution treatment at 510℃ for 6 hours and 530℃ for 6 hours.

[0058] Step 6: After solution treatment, perform aging treatment within 12 hours. The aging temperature is 160℃ and the holding time is 10 hours.

[0059] Comparative Example 1:

[0060] The cast aluminum alloy provided in this comparative example has the following elemental composition by mass percentage: 8.2% Si; 0.2% Mg; 0.24% Cu; 0.13% Mn; 0.15% Zr; 0.08% Ti; 0.016% Sr; with the balance being Al and unavoidable impurities.

[0061] The preparation process of the above-mentioned cast aluminum alloy includes the following steps:

[0062] Step 1: Calculate the mass of each raw material according to the element formula and prepare the raw materials. The raw materials are AlSi2O, metallic magnesium, AlCu5O, AlMn10, AlTi10, AlSr10, and AlZr5.

[0063] Step 2: Add the ingredients AlSi20, metallic magnesium, AlCu50, AlMn10, AlTi10, AlSr10, and AlZr5 to the melting furnace in sequence for melting. Control the temperature of the aluminum liquid at 730-760℃. Magnesium and rare earth elements are added last, and some rare earth elements are added as magnesium-rare earth intermediate alloys to reduce the loss of magnesium and rare earth elements.

[0064] Step 3: Refine and remove slag to obtain qualified components. Then, use 99.9% pure argon gas to blow gas into the aluminum alloy molten metal in the melting furnace for 5 minutes to refine it and reduce the gas content in the molten aluminum.

[0065] Step 4: Control the casting temperature between 660℃ and 700℃ and perform slow casting.

[0066] Step 5: Use a two-stage solution treatment at 500℃ for 6 hours and at 520℃ for 10 hours.

[0067] Step 6: After solution treatment, perform aging treatment within 12 hours. The aging temperature is 150℃ and the holding time is 12 hours.

[0068] Comparative Example 2:

[0069] The cast aluminum alloy provided in this comparative example has the following elemental composition by mass percentage: 9.2% Si; 0.35% Mg; 0.30% Cu; 0.15% Mn; 0.20% Zr; 0.02% Ti; 0.011% Sr; with the balance being Al and unavoidable impurities.

[0070] The preparation process of the above-mentioned cast aluminum alloy includes the following steps:

[0071] Step 1: Calculate the mass of each raw material according to the element formula and prepare the raw materials. The raw materials are AlSi2O, metallic magnesium, AlCu5O, AlMn10, AlTi10, AlSr10, and AlZr5.

[0072] Step 2: Add the ingredients AlSi20, metallic magnesium, AlCu50, AlMn10, AlTi10, AlSr10, and AlZr5 to the melting furnace in sequence for melting. Control the temperature of the aluminum liquid at 730-760℃. Magnesium and rare earth elements are added last, and some rare earth elements are added as magnesium-rare earth intermediate alloys to reduce the loss of magnesium and rare earth elements.

[0073] Step 3: Refine and remove slag to obtain qualified components. Then, use 99.9% pure argon gas to blow gas into the aluminum alloy molten metal in the melting furnace for 5 minutes to refine it and reduce the gas content in the molten aluminum.

[0074] Step 4: Control the casting temperature between 660℃ and 700℃ and perform slow casting.

[0075] Step 5: Use a two-stage solution treatment at 500℃ for 12 hours.

[0076] Step 6: After solution treatment, perform aging treatment within 12 hours. The aging temperature is 150℃ and the holding time is 12 hours.

[0077] Example of effect:

[0078] The mechanical properties and secondary dendrite spacing of the cast aluminum alloys prepared in Examples 1-3 and Comparative Examples 1-2 were measured, and the results are shown in Table 1 below. Figures 1-5 As shown;

[0079] Table 1

[0080] Example 1 392 8 21 Example 2 426 9 16 Example 3 411 7 13 Comparative Example 1 331 7 28 Comparative Example 2 368 4 25

[0081] From the above table 1 and Figures 1-5 It is understood that the aluminum alloy provided by this invention has high strength and good casting processability, and can be used as a next-generation engine block material to further reduce the weight of automobile engine blocks and meet the needs of automobile lightweighting.

[0082] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A cast aluminum alloy, characterized in that, The alloy comprises, by mass percentage: 6.2% Si; 0.42% Mg; 3.2% Cu; 0.006% Mn; 0.01% Zr; 0.17% Ti; 0.082% Sr; 0.15% La; 0.01% Ce; 0.2% Pr, with the balance being Al and unavoidable impurities; the secondary dendrite spacing of the cast aluminum alloy composed of the above elements is 21 μm. Or 9.5% Si; 0.43% Mg; 3.0% Cu; 0.14% Mn; 0.16% Zr; 0.055% Ti; 0.12% Sr; 0.13% La; 0.10% Ce; 0.01% Y; 0.2% Gd; 0.05% Pr, with the balance being Al and unavoidable impurities; the secondary dendrite spacing of the cast aluminum alloy composed of the above elements is 16 μm; Or 8.5% Si; 0.56% Mg; 3.8% Cu; 0.16% Mn; 0.12% Zr; 0.12% Ti; 0.063% Sr; 0.07% La; 0.12% Ce; 0.35% Y; 0.34% Gd; 0.06% Pr, with the balance being Al and unavoidable impurities; the secondary dendrite spacing of the cast aluminum alloy composed of the above elements is 13 μm.

2. A method for preparing the cast aluminum alloy according to claim 1, characterized in that, include: (1) According to the aluminum alloy formula, AlSi20, metallic magnesium, AlCu50, AlMn10, AlTi10, AlSr10, AlZr5, AlLa20, AlCe10, AlY20, MgGd80, and MgPr20 are used as raw materials for batching. (2) The raw materials in (1) are put into the smelting furnace in sequence for smelting, with metallic magnesium and raw materials containing rare earth elements being added last; (3) The refining, slag removal, refining, casting, two-stage solution treatment and aging treatment are carried out in sequence; (3) The two-stage solution treatment is: heat preservation at 500-510℃ for 3-6 hours; heat preservation at 520-530℃ for 6-10 hours; and aging treatment is heat preservation at 150-170℃ for 5-12 hours.

3. The preparation method according to claim 2, characterized in that, (2) The melting temperature is 730-760℃, and (3) The casting temperature is 660-700℃.

4. The preparation method according to claim 2, characterized in that, (3) The refining process is as follows: use argon gas with a purity of 99.9% to blow gas into the aluminum alloy liquid in the melting furnace for 5 minutes.

5. An application of the cast aluminum alloy according to claim 1, characterized in that, Used in the manufacture of automobile engine cylinder blocks.

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