Die-casting aluminum alloy, aluminum alloy casting and preparation method of aluminum alloy casting

Abstract

The invention belongs to the technical field of alloy materials, and discloses a die-casting aluminum alloy, an aluminum alloy casting and a preparation method of the aluminum alloy casting. The die-casting aluminum alloy comprises the following components in percentage by mass: 11%-13% of Si, 0.9% of Fe, 1.0%-3.5% of Cu, 0.15%-0.5% of Mn, 0.3%-1.0% of Mg, 0.1%-0.3% of Zn, 0.5%-0.7% of Ni, 0.1% of Pb, 0.2% of Sn and the balance of Al and inevitable impurities on the basis of the overall mass of the die-casting aluminum alloy. The aluminum alloy casting is high in density and small in apparent porosity, after die-casting forming, secondary surface treatment is not needed, T6 heat treatment process strengthening can be directly conducted, the aluminum alloy casting obtains higher yield strength, tensile strength, fatigue resistance, corrosion resistance and hardness, time consumed by the machining procedure is greatly shortened, the cost is greatly reduced, and the production efficiency is improved. And the production efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy materials, and in particular relates to a die-casting aluminum alloy, an aluminum alloy casting and a preparation method thereof. Background Art

[0002] Aluminum alloy is a major alloy material in current industrial production due to its excellent performance. In particular, in the automobile industry, aluminum alloy is often used for integrated die casting of the car body and its components to achieve the effect of weight reduction and strengthening. However, most of the conventional aluminum alloys currently have the following problems when integrated die casting: First, the existing aluminum alloys have poor shrinkage compensation, and the molded castings are prone to shrinkage defects and shrinkage holes, and there are many surface cracks, which seriously affect the quality of the castings; second, the fluidity is poor, and when molding castings with small cavities, it cannot flow smoothly through the mold cavity; third, the integrated die casting process is used, and the aluminum alloy melt is easy to absorb air, resulting in surface pinhole defects after the casting is formed, and subcutaneous pore defects are formed inside the casting, which cannot be subjected to solution heat treatment. Summary of the invention

[0003] The object of the present invention is to provide a die-cast aluminum alloy to solve the technical problems that during die-casting of the aluminum alloy in the prior art, the aluminum alloy melt has poor fluidity, the aluminum alloy melt is easy to absorb air, resulting in high apparent porosity, many shrinkage defects, resulting in poor casting quality, inability to flow smoothly through small cavities, and the surface cannot be directly strengthened.

[0004] The present invention also aims to provide an aluminum alloy casting to solve the same technical problem as above.

[0005] The present invention also aims to provide a method for preparing an aluminum alloy casting to solve the same technical problem as above.

[0006] To achieve the above purpose, the technical solution of die-casting aluminum alloy provided by the present invention is: A die-cast aluminum alloy, based on the overall quality of the die-cast aluminum alloy, includes: 11-13% Si, 0.9% Fe, 1.0-3.5% Cu, 0.15-0.5% Mn, 0.3-1.0% Mg, 0.1-0.3% Zn, 0.5-0.7% Ni, 0.1% Pb, 0.2% Sn, The balance is Al and inevitable impurities.

[0007] Furthermore, the content of Mn is 0.5 mass %.

[0008] Furthermore, the content of Zn is 0.1 mass %.

[0009] Furthermore, the content of Ni is 0.5 mass %.

[0010] The beneficial effects of the die-cast aluminum alloy of the present invention are: 1. The aluminum alloy molten liquid does not absorb air for a long time, which ensures the casting quality, good fluidity, slow self-solidification time, and the casting cavity such as the spiral tube gap can flow through the filling mold, and can form castings with small cavities; 2. Good shrinkage compensation performance, good casting quality, not prone to shrinkage, effectively overcoming the problem of many cracks in aluminum alloy after forming in the prior art; 3. Aluminum alloy has a low expansion coefficient. After the cast casting is solidified, the casting has stable dimensions, good casting performance, no tendency to thermal cracking, high air tightness and small linear shrinkage.

[0011] 4. Aluminum alloy, in a hypereutectic phase, refines primary silicon, has a more uniform grain structure, high density, and small apparent porosity. When used in piston casting, it greatly improves the high temperature performance, wear resistance and dimensional stability of the piston; cast structural parts have high strength, high weldability and corrosion resistance, good casting mechanical properties, good heat resistance, and good aluminum liquid flow performance. It can be heat-treated and strengthened, and has high mechanical properties at high temperature and room temperature.

[0012] To achieve the above object, the technical solution of the aluminum alloy casting provided by the present invention is: An aluminum alloy casting composed of a die-cast aluminum alloy.

[0013] Furthermore, the apparent porosity of the aluminum alloy casting is less than 0.05%.

[0014] Furthermore, a die-cast aluminum alloy, based on the overall quality of the die-cast aluminum alloy, comprises: 11-13% Si, 0.9% Fe, 1.0-3.5% Cu, 0.15-0.5% Mn, 0.3-1.0% Mg, 0.1-0.3% Zn, 0.5-0.7% Ni, 0.1% Pb, 0.2% Sn, The balance is Al and inevitable impurities.

[0015] Furthermore, the content of Mn is 0.5 mass %.

[0016] Furthermore, the content of Zn is 0.1 mass %.

[0017] Furthermore, the content of Ni is 0.5 mass %.

[0018] The beneficial effects of the aluminum alloy casting of the present invention are: 1. The aluminum alloy molten liquid does not absorb air for a long time, which ensures the casting quality, good fluidity, slow self-solidification time, and the casting cavity such as the spiral tube gap can flow through the filling mold, and can form castings with small cavities; 2. Good shrinkage compensation performance, good casting quality, not prone to shrinkage, effectively overcoming the problem of many cracks in aluminum alloy after forming in the prior art; 3. Aluminum alloy has a low expansion coefficient. After the cast casting is solidified, the casting has stable dimensions, good casting performance, no tendency to thermal cracking, high air tightness and small linear shrinkage.

[0019] 4. Aluminum alloy, in a hypereutectic phase, refines primary silicon, has a more uniform grain structure, high density, and small apparent porosity. When used in piston casting, it greatly improves the high temperature performance, wear resistance and dimensional stability of the piston; cast structural parts have high strength, high weldability and corrosion resistance, good casting mechanical properties, good heat resistance, and good aluminum liquid flow performance. It can be heat-treated and strengthened, and has high mechanical properties at high temperature and room temperature.

[0020] To achieve the above object, the technical solution of the method for preparing aluminum alloy castings provided by the present invention is: A method for preparing an aluminum alloy casting comprises the following steps: 1) Die-casting aluminum alloy proportioning, melting aluminum and other metal elements or their aluminum intermediate alloys into a molten liquid; 2) Adjust the melt temperature to 800℃-820℃, add phosphorus alloy modifier, make the phosphorus content in the solution 50-110PPM, keep warm for 20-50 minutes until the phosphorus alloy modifier is completely melted and mixed evenly; 3) Refining, slag removal, degassing and casting to obtain the finished product.

[0021] Furthermore, in step 1), the melt is sampled, the content of each element is detected, and the composition of each element is adjusted to a ratio range by supplementing raw materials.

[0022] Furthermore, the finished product is strengthened by a T6 heat treatment process.

[0023] Furthermore, the T6 heat treatment process includes the following steps in sequence: 1) Solution treatment: (1) Heating to 480°C in 1h40min; (2) Heating to 510°C in 40 minutes; (3) 510℃ for 7h; 2) Quench at 80℃ and place at room temperature for 24h; 3) Time-limited processing (1) Heating to 145°C in 30 minutes; (2) Heating to 160°C in 10 minutes; (3) Keep at 160℃ for 8h.

[0024] Furthermore, a die-cast aluminum alloy, based on the overall quality of the die-cast aluminum alloy, comprises: 11-13% Si, 0.9% Fe, 1.0-3.5% Cu, 0.15-0.5% Mn, 0.3-1.0% Mg, 0.1-0.3% Zn, 0.5-0.7% Ni, 0.1% Pb, 0.2% Sn, The balance is Al and inevitable impurities.

[0025] Furthermore, the content of Mn is 0.5 mass %.

[0026] Furthermore, the content of Zn is 0.1 mass %.

[0027] Furthermore, the content of Ni is 0.5 mass %.

[0028] Furthermore, an aluminum alloy casting composed of a die-cast aluminum alloy.

[0029] Furthermore, the apparent porosity of the aluminum alloy casting is less than 0.05%.

[0030] The beneficial effects of the method for preparing the aluminum alloy casting of the present invention are: 1. The aluminum alloy molten liquid does not absorb air for a long time, which ensures the casting quality, good fluidity, slow self-solidification time, and the casting cavity such as the spiral tube gap can flow through the filling mold, and can form castings with small cavities; 2. Good shrinkage compensation performance, good casting quality, not prone to shrinkage, effectively overcoming the problem of many cracks in aluminum alloy after forming in the prior art; 3. Aluminum alloy has a low expansion coefficient. After the cast casting is solidified, the casting has stable dimensions, good casting performance, no tendency to thermal cracking, high air tightness and small linear shrinkage.

[0031] 4. The metallographic structure of aluminum alloy castings is hypereutectic, with refined primary silicon, more uniform grain structure, high density, and small apparent porosity. When used in piston casting, it greatly improves the high temperature performance, wear resistance and dimensional stability of the piston; the cast structural parts have high strength, high weldability and corrosion resistance, good casting mechanical properties, good heat resistance, and good aluminum liquid flow performance. It can be heat-treated and strengthened, and has high mechanical properties at high temperature and room temperature.

[0032] 5. The aluminum alloy casting of the present invention has high density and small apparent porosity. After die-casting, it does not need to undergo secondary surface treatment and can be directly strengthened by T6 heat treatment process, so that the aluminum alloy casting obtains higher yield strength, tensile strength, fatigue resistance, corrosion resistance and hardness, greatly reducing the time and cost of the processing process and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a metallographic determination diagram of the apparent porosity of the aluminum alloy casting of the present invention. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the present invention, "not containing a certain element" means that the certain element is not intentionally added, and does not exclude the fact that the element is contained as an impurity. In addition, the range "AB" of the content means that the contents shown by the numbers A and B are included.

[0036] A die-cast aluminum alloy, based on the overall quality of the die-cast aluminum alloy, includes: 11-13% Si can improve the casting mold of the alloy, improve the permeability of the alloy in the molten state, facilitate the alloy melt to pass through narrow gaps, and facilitate the flow through the small or narrow gaps. However, the solubility of Si in the alloy is limited, and too high a content has little effect on strengthening the alloy, but reduces the plasticity of the alloy. Therefore, in a most preferred embodiment, the content of Si is 11% by mass.

[0037] 0.9% Fe, Fe will increase the strength of the alloy, but too much Fe will reduce the mechanical properties of the alloy such as corrosion resistance and elongation.

[0038] 1.0-3.5% Cu, Cu can form Al-Ni-Cu phase and CuAl2 phase in Al-Si-Cu-Ni alloy, which can improve the room temperature and high temperature strength of the alloy, but the elongation decreases. The inventor's research shows that the higher the Cu content, the more obvious the aging hardening characteristics of the alloy, the higher the aging temperature, the faster the aging hardening rate. In this formula, when the Cu content is greater than 1.5%, although a skeletal metallographic structure will be produced as the Cu content increases, the tensile strength of the alloy is not greatly improved, but it will affect the hot melt fluidity of the alloy. Therefore, in a most preferred embodiment, the Cu content is 1.5% by mass.

[0039] 0.15-0.5% Mn. The increase of Mn content will improve the high temperature tensile strength and hardness of the alloy, and also reduce the thermal expansion system of the aluminum alloy. However, the increase of Mn content will lead to a decrease in the overall strength of the alloy during T6 strengthening. Therefore, in a most preferred embodiment, the Mn content is 0.5 mass%.

[0040] 0.3-1.0% Mg. The increase of Mg content will increase the solid solution content in the alloy, improve the mechanical strength and thermal conductivity of the alloy. However, when the Mg content exceeds 1.0%, excess Mg will form more Mg2Si, which will affect the strength of the alloy. Therefore, in a most preferred embodiment, the Mg content is 0.7% by mass.

[0041] 0.1-0.3% Zn. The increase of Zn content can improve the strength of the alloy. However, with the increase of Zn, the stress cracking resistance of the alloy becomes more serious. Therefore, in a most preferred embodiment, the Zn content is 0.1 mass %.

[0042] 0.5-0.7% Ni, the Ni content has a significant effect on the microstructure of the alloy. The higher the content, the higher the high-temperature tensile strength of the alloy, and the room-temperature strength will decrease. In addition, as the Ni content increases, the elongation of the alloy will also decrease. Therefore, in a most preferred embodiment, the Ni content is 0.5 mass %.

[0043] 0.1% Pb is mainly used to increase the solubility of Zn.

[0044] 0.2% Sn will improve the solid solution strengthening of the alloy, but excessive Sn will reduce the strength of the alloy.

[0045] The balance is Al and inevitable impurities.

[0046] The method for preparing an aluminum alloy casting using the die-cast aluminum alloy under the above conditions comprises the following steps: 1) Die-casting aluminum alloy proportioning, melting aluminum and other metal elements or their aluminum intermediate alloys into a molten liquid; 2) Adjust the melt temperature to 800℃-820℃, add phosphorus alloy modifier, make the phosphorus content in the solution 50-110PPM, keep warm for 20-50 minutes until the phosphorus alloy modifier is completely melted and mixed evenly; 3) Refining, slag removal, degassing and casting to obtain the finished product.

[0047] In a preferred embodiment, in order to ensure the composition ratio of the die-casting aluminum alloy of the present invention, in step 1), the melt is sampled, the content of each element is detected, and the composition of each element is adjusted to a ratio range by supplementing raw materials.

[0048] In a preferred embodiment, the finished aluminum alloy casting is strengthened by a T6 heat treatment process.

[0049] In a preferred embodiment, the T6 heat treatment process for the finished aluminum alloy casting comprises the following steps in sequence: 1) Solution treatment: (1) Heating to 480°C in 1h40min; (2) Heating to 510°C in 40 minutes; (3) 510℃ for 7h; 2) Quench at 80℃ and place at room temperature for 24h; 3) Time-limited processing (1) Heating to 145°C in 30 minutes; (2) Heating to 160°C in 10 minutes; (3) Keep at 160℃ for 8h.

[0050] Examples and Comparative Examples Example

[0051] Based on the overall quality of die-cast aluminum alloy: 11% Si, 0.9% Fe, 1.5% Cu, 0.5% Mn, 0.7% Mg, 0.1% Zn, 0.5% Ni, 0.1% Pb, 0.2% Sn, and the balance is Al and inevitable impurities. Example

[0052] Based on the overall quality of die-cast aluminum alloy: 13% Si, 0.9% Fe, 3.5% Cu, 0.5% Mn, 1.0% Mg, 0.3% Zn, 0.7% Ni, 0.1% Pb, 0.2% Sn, and the balance is Al and inevitable impurities. Example

[0053] Based on the overall quality of die-cast aluminum alloy: 12% Si, 0.9% Fe, 2% Cu, 0.4% Mn, 0.7% Mg, 0.2% Zn, 0.6% Ni, 0.1% Pb, 0.2% Sn, and the balance is Al and inevitable impurities.

[0054] Comparative Example 1 Based on the overall quality of die-cast aluminum alloy: 10% Si, 1% Fe, 1.0% Cu, 1% Mn, 0.3% Mg, 0.4% Zn, 0.5% Ni, 0.1% Pb, 0.2% Sn, the balance is Al and unavoidable impurities Comparative Example 2 Based on the overall quality of die-cast aluminum alloy: 14% Si, 1% Fe, 4% Cu, 0.6% Mn, 0.3% Mg, 0.3% Zn, 0.7% Ni, 0.15% Pb, 0.3% Sn, and the balance is Al and inevitable impurities.

[0055] Examples 1-3 and Comparative Examples 1-2 were made into aluminum alloy rods under the conditions of the above-mentioned preparation method. During this process, the fluidity was tested respectively according to the aluminum alloy fluidity testing device and testing method disclosed in Chinese Patent 202211349777.X.

[0056] The aluminum alloy test bar was machined into a standard specimen and then subjected to T6 heat treatment. Then, a room temperature tensile test was performed on an electronic universal material testing machine. The mechanical properties of the specimen were tested using GB / T228.1_2010 Metallic Material Tensile Test Part 1: Room Temperature Test Method. At the same time, the apparent porosity of the specimen was determined according to GB3489_2015. As an example, Figure 1 This is the metallographic determination diagram of the apparent porosity of Example 1.

[0057] 1. Liquidity Test Liquidity Index Example 1 3623 Example 2 3528 Example 3 3551 Comparative Example 1 3219 Comparative Example 2 3402 2. Performance Test Serial number Tensile strength (MPa) Yield strength (MPa) Elongation(%) Hardness(HBW) Apparent porosity (volume fraction %) Example 1 388 272 7.0 131 0.02 Example 2 380 284 7.5 126 0.04 Example 3 380 285 6.6 131 0.03 Comparative Example 1 335 281 1.5 131 0.13 Comparative Example 2 361 289 2.5 126 0.21 It can be seen from the fluidity test and performance test that the data of Examples 1-3 are much greater than the data of Comparative Examples 1-2, indicating that the aluminum alloy formula and preparation method of the present invention can effectively improve the casting fluidity as well as the tensile strength, yield strength and elongation of the aluminum alloy.

Claims

1. A die-cast aluminum alloy, characterized in that: The overall quality of die-cast aluminum alloys includes: 11-13% Si, 0.9% Fe, 1.0-3.5% Cu, 0.15-0.5% Mn, 0.3-1.0% Mg, 0.1-0.3% Zn, 0.5-0.7% Ni, 0.1% Pb, 0.2% Sn, The balance is Al and inevitable impurities.

2. The die-cast aluminum alloy according to claim 1, characterized in that: The content of Mn was 0.5 mass %.

3. The die-cast aluminum alloy according to claim 1, characterized in that: The Zn content was 0.1 mass %.

4. The die-cast aluminum alloy according to claim 1, characterized in that: The content of Ni was 0.5 mass %.

5. An aluminum alloy casting composed of the die-casting aluminum alloy according to any one of claims 1 to 4.

6. The aluminum alloy casting according to claim 5, characterized in that: The apparent porosity of aluminum alloy castings is less than 0.05%.

7. A method for preparing an aluminum alloy casting according to claim 5 or 6, characterized in that: The following steps are involved: 1) The die-casting aluminum alloy according to any one of claims 1 to 4 is prepared by smelting aluminum and other metal elements or their aluminum intermediate alloys into a molten liquid; 2) Adjust the melt temperature to 800℃-820℃, add phosphorus alloy modifier, make the phosphorus content in the solution 50-110PPM, keep warm for 20-50 minutes until the phosphorus alloy modifier is completely melted and mixed evenly; 3) Refining, slag removal, degassing and casting to obtain the finished product.

8. The method for preparing an aluminum alloy casting according to claim 7, characterized in that: In step 1), the melt is sampled, the content of each element is detected, and the composition of each element is adjusted to a ratio range by adding raw materials.

9. The method for preparing an aluminum alloy casting according to claim 7, characterized in that: The finished product is strengthened by T6 heat treatment process.

10. The method for preparing an aluminum alloy casting according to claim 9, characterized in that: The T6 heat treatment process includes the following steps in sequence: 1) Solution treatment: (1) Heating to 480°C in 1h40min; (2) Heating to 510°C in 40 minutes; (3) 510℃ for 7h; 2) Quench at 80℃ and place at room temperature for 24h; 3) Time-limited processing (1) Heating to 145°C in 30 minutes; (2) Heating to 160°C in 10 minutes; (3) Keep at 160℃ for 8h.

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