Die-cast aluminum alloys and their preparation methods, automotive structural components and vehicles

Abstract

This application provides a die-cast aluminum alloy and its preparation method, automotive structural parts and vehicles. The die-cast aluminum alloy includes Si, and the mass percentage of Si, Wt(Si)%, satisfies the formula shown in Formula I, where V is the ratio of the cooling rate to 100. The Si content satisfies Formula I, which helps to make the die-cast aluminum alloy have both excellent yield strength and impact toughness.

Description

Technical Field

[0001] This application relates to the field of aluminum alloys, and more particularly to a die-cast aluminum alloy and its preparation method, automotive structural components, and vehicles. Background Technology

[0002] With the trend towards lightweighting in automobiles, aluminum alloy structural components, such as body frames, energy-absorbing boxes, and battery pack housings, are increasingly adopting integrated die-casting processes to improve production efficiency.

[0003] Most aluminum alloys used for structural components on the market are wrought aluminum alloys, which are insufficient to meet the integrated die-casting requirements of complex thin-walled structures. Furthermore, the brittle phases inside die-cast aluminum alloys tend to agglomerate, affecting their yield strength and impact toughness. Summary of the Invention

[0004] This application provides a die-cast aluminum alloy and its preparation method, an automotive structural component, and a vehicle, aiming to improve the yield strength and impact toughness of die-cast aluminum alloys.

[0005] To achieve the above objectives, in a first aspect, embodiments of this application provide a die-cast aluminum alloy, the die-cast aluminum alloy comprising Si; The mass percentage of Si, Wt(Si)%, satisfies the formula shown in Equation I: Wt(Si) = 11.33 - 0.0219V 3 +0.2792V 2 -1.4403V±1 type I; Where V is the ratio of the cooling rate to 100, and the unit of cooling rate is K / S.

[0006] Optionally, in some embodiments of this application, the mass percentage of Si, Wt(Si)%, satisfies the formula shown in Equation III: Wt(Si) = 11.33 - 0.0219V 3 +0.2792V 2 -1.4403V±0.7Form III.

[0007] Optionally, in some embodiments of this application, the value of V ranges from 1 to 9; Preferably, the value of V ranges from 1 to 7.

[0008] Optionally, in some embodiments of this application, the mass percentage of Si in the die-cast aluminum alloy is 6% to 11%.

[0009] Optionally, in some embodiments of this application, the die-cast aluminum alloy further includes Ti; The mass percentage of Ti, Wt(Ti)%, satisfies the formula shown in Equation II: Wt(Ti) ​​= 0.2012e -0.177(V) ±0.02 Formula II.

[0010] Optionally, in some embodiments of this application, the mass percentage of Ti, Wt(Ti)%, satisfies the formula shown in Equation IV: Wt(Ti) ​​= 0.2012e -0.177(V) ±0.015 Form IV.

[0011] Optionally, in some embodiments of this application, the mass percentage of Ti in the die-cast aluminum alloy is 0.02% to 0.17%.

[0012] Optionally, in some embodiments of this application, the die-cast aluminum alloy further includes functional elements; The functional element includes at least one of Mn, Mg, Sr, Cu, Fe, and Zn.

[0013] The yield strength of the die-cast aluminum alloy is greater than or equal to 105 MPa; and / or The impact toughness of the die-cast aluminum alloy is greater than or equal to 250 kJ / m. 2 ; Preferably, the yield strength of the die-cast aluminum alloy is greater than or equal to 120 MPa; Preferably, the impact toughness of the die-cast aluminum alloy is greater than or equal to 260 kJ / m. 2 .

[0014] Secondly, embodiments of this application provide a method for preparing a die-cast aluminum alloy, used to prepare the aforementioned die-cast aluminum alloy, comprising the following steps: Provide aluminum alloy liquid; The aluminum alloy liquid is die-cast at a cooling rate to obtain the die-cast aluminum alloy.

[0015] Optionally, in some embodiments of this application, the cooling rate ranges from 100K / S to 900K / S; Preferably, the cooling rate ranges from 100 K / S to 700 K / S.

[0016] Optionally, in some embodiments of this application, the mold temperature range in the die casting process is 50°C. o C to 320 o C; and / or The temperature range of the molten aluminum alloy is 660°C. o C to 730o C; and / or The die-casting speed in the die-casting process ranges from 2.0 m / s to 6.0 m / s; and / or The casting pressure in the die casting process is 30 MPa to 60 MPa.

[0017] Thirdly, embodiments of this application provide an automotive structural component, the automotive structural component comprising the die-cast aluminum alloy as described above or the die-cast aluminum alloy prepared by the aforementioned method.

[0018] Fourthly, embodiments of this application provide a vehicle, the vehicle comprising the aforementioned automotive structural components or the aforementioned die-cast aluminum alloy.

[0019] This application provides a die-cast aluminum alloy comprising Si, wherein the mass percentage of Si, Wt(Si)%, satisfies the formula shown in Formula I, where V is the ratio of the cooling rate to 100; the Si content satisfies Formula I, which helps the die-cast aluminum alloy to possess both excellent yield strength and impact toughness. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a graph showing the relationship between the mass percentage of Si and the cooling rate in some embodiments of this application; Figure 2 This is a graph showing the relationship between the mass percentage of Si and the cooling rate in some embodiments of this application; Figure 3 This is a graph showing the relationship between the mass percentage of Ti and the cooling rate in some embodiments of this application; Figure 4 This is a graph showing the relationship between the mass percentage of Ti and the cooling rate in some embodiments of this application; Figure 5 This is a metallographic image of the aluminum alloy of Embodiment 1-1 of this application; Figure 6 This is a metallographic image of the aluminum alloy of Embodiment 7-1 of this application; Figure 7 This is a metallographic image of the aluminum alloy of Comparative Example 1-1 of this application; Figure 8 These are metallographic images of the aluminum alloys of Comparative Examples 1-4 of this application. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0023] Currently, most research on aluminum alloys with good impact resistance focuses on wrought aluminum, with no relevant reports on die-cast aluminum. The main reason is that die-cast aluminum alloys, due to their high degree of alloying and uneven solute distribution caused by rapid forming, are prone to the segregation of brittle phases at grain boundaries. This makes the aluminum alloys prone to failure at the brittle phase aggregation points when subjected to impact loads. Therefore, their impact resistance is a weaker property compared to die-cast aluminum alloys.

[0024] According to a first aspect of the embodiments of this application, a die-cast aluminum alloy is provided, the die-cast aluminum alloy comprising Si; The mass percentage of Si, Wt(Si)%, satisfies the formula shown in Equation I: Wt(Si) = 11.33 - 0.0219V 3 +0.2792V 2 -1.4403V±1 type I; Where V is the ratio of the cooling rate to 100, and the unit of cooling rate is K / S.

[0025] By adopting the above scheme, the mass percentage of Si satisfies the formula shown in Equation I, which helps to give the die-cast aluminum alloy both excellent yield strength and impact toughness. This is because the cooling rate of the die-cast aluminum alloy during die-casting is different, resulting in different strengthening effects from the AlSi eutectic structure after fine grain strengthening. Moreover, the mass percentage of Si has a significant impact on the latent heat of crystallization of the die-cast aluminum alloy. The release of latent heat during the solidification process of the aluminum alloy can easily affect the cooling rate. Combining its alloy composition ratio characteristics and die-casting characteristics, and using the phase diagram calculation, the formula shown in Equation I is obtained.

[0026] By combining the excellent microstructure with macroscopic mechanical properties and experimental results on the microstructure and properties exhibited by the corresponding components at different cooling rates, the relationship between the mass percentage of the corresponding components and the cooling rate is summarized.

[0027] Figure 1 This is a graph showing the relationship between the mass percentage of Si (Wt(Si)%) and the cooling rate in some embodiments of this application. Figure 1It can be seen that, under the same cooling rate, the corresponding abscissas (mass percentage of Si) on the two curves can be obtained respectively. These two abscissas constitute a selectable range. Obtaining the mass percentage of Si within this selectable range can result in fine surface grains and uniform distribution of eutectic Si and Al matrix, thus ensuring high yield strength of aluminum alloy; the core structure has a high proportion of Al matrix and no primary Si segregation or small primary Si size, thus ensuring excellent toughness of the core structure, and realizing the preparation of aluminum alloy with excellent impact toughness and yield strength.

[0028] The cooling rate in this embodiment refers to the cooling rate of the molten aluminum alloy after it is injected into the mold. This cooling rate can be obtained by testing the cooling rate using a sensor device at the mold end of the die-casting mold.

[0029] In some embodiments of this application, the value of V ranges from 1 to 9. Further, the value of V ranges from 1 to 7. Exemplarily, V can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or any value between two adjacent values ​​mentioned above.

[0030] In some embodiments of this application, the mass percentage of Si, Wt(Si)%, satisfies the formula shown in Equation III: Wt(Si) = 11.33 - 0.0219V 3 +0.2792V 2 -1.4403V±0.7Form III.

[0031] By adopting the above scheme and further optimizing the range of Formula I, if the mass percentage of Si satisfies the formula shown in Formula III, a die-cast aluminum alloy with both superior yield strength and impact toughness can be obtained.

[0032] Figure 2 This is a graph showing the relationship between the mass percentage of Si and the cooling rate in some embodiments of this application. Figure 2 It can be seen that the range of possible values ​​for the two horizontal axes corresponding to the same vertical axis is narrower. By taking values ​​within this narrower range, aluminum alloys with better impact toughness and yield strength can be obtained.

[0033] In some embodiments of this application, the mass percentage of Si in the die-cast aluminum alloy is 6% to 11%.

[0034] By adopting the above scheme, the AlSi eutectic structure has a strengthening effect, and an appropriate Si content helps to ensure that the eutectic structure has a good strengthening effect; however, Si has a low effect on impact toughness at the same mass percentage, so the Si content should not be too high.

[0035] In some embodiments of this application, the die-cast aluminum alloy further includes Ti; The mass percentage of Ti, Wt(Ti)%, satisfies the formula shown in Equation II: Wt(Ti) ​​= 0.2012e -0.177(V) ±0.02 Formula II.

[0036] By adopting the above scheme, the refining effect of Ti in the Al matrix varies under different cooling rates. The embodiments of this application can effectively refine the proportional relationship between Ti and cooling rate in die-cast aluminum alloys.

[0037] Figure 3 This is a graph showing the relationship between the mass percentage of Ti (Wt(Si)%) and the cooling rate in some embodiments of this application. Figure 3 It can be seen that, under the same cooling rate, the corresponding horizontal axis (Ti%) on the two curves can be obtained. These two horizontal axes constitute the selectable range of Ti. Obtaining the mass percentage of Ti within this selectable range can achieve excellent grain refinement effect, while also reducing excessive Ti from becoming impurity-like, thereby ensuring the yield strength and impact toughness of the die-cast aluminum alloy.

[0038] In some embodiments of this application, the mass percentage of Ti, Wt(Ti)%, satisfies the formula shown in Equation IV: Wt(Ti) ​​= 0.2012e -0.177(V) ±0.015 Form IV.

[0039] Figure 4 This is a graph showing the relationship between the mass percentage of Ti and the cooling rate in some embodiments of this application. Figure 4 It can be seen that the range of possible values ​​for the two horizontal axes corresponding to the same vertical axis is narrower. By taking values ​​within this narrower range, die-cast aluminum alloys with both superior yield strength and impact toughness can be obtained.

[0040] In some embodiments of this application, the mass percentage of Ti in the die-cast aluminum alloy is 0.02% to 0.17%.

[0041] By adopting the above scheme, high-melting-point elements such as Ti can play a grain-refining strengthening role. Under a suitable cooling rate, the grains gradually grow, and the Ti content has a more obvious effect on grain refinement. Ti has low solubility in aluminum alloys, with a solubility of only 0.12 wt% at 938 K. Under rapid cooling conditions, excessive Ti is very likely to precipitate prematurely.

[0042] In some embodiments of this application, the die-cast aluminum alloy further includes functional elements; The functional elements include at least one of Mn, Mg, Sr, Cu, Fe, and Zn.

[0043] By adopting the above schemes, Mg can play a prominent strengthening role, mainly relying on the Mg2Si phase and the AlSiMgMn / Fe phase, which helps to improve the impact toughness of die-cast aluminum alloys. The strengthening phases of Mn mainly include the MnAl6 phase and the AlFeMnSi phase. The strengthening effect of Mn on die-cast aluminum alloys is mostly a combined strengthening, and the formed strengthening phases are mostly spherical or short rod-shaped. Its effect on strength improvement and impact toughness of aluminum alloys is weaker than that of Mg2Si-type strengthening phases. At the same time, Mn can improve the erosion effect on die-casting molds. The strengthening phases of Cu mainly include the CuAl2 phase and the AlSiCuFe phase. In the die-casting process, an appropriate amount of Cu can ensure a moderate amount of precipitated phases and a more uniform distribution of precipitated phases. An appropriate amount of Fe helps to improve the erosion effect on die-casting molds.

[0044] In some embodiments of this application, the yield strength of the die-cast aluminum alloy is greater than or equal to 110 MPa. Further, the yield strength of the die-cast aluminum alloy is greater than or equal to 120 MPa. Exemplarily, the yield strength of the die-cast aluminum alloy can be 110 MPa, 111 MPa, 112 MPa, 113 MPa, 115 MPa, 117 MPa, 120 MPa, 123 MPa, 124 MPa, 125 MPa, 127 MPa, 128 MPa, 130 MPa, 132 MPa, 140 MPa, or any value between two adjacent values ​​mentioned above.

[0045] In some embodiments of this application, the impact toughness of the die-cast aluminum alloy is greater than or equal to 250 kJ / m. 2 Furthermore, the impact toughness of the die-cast aluminum alloy is greater than or equal to 300 kJ / m. 2 For example, the impact toughness of die-cast aluminum alloys can be 253 kJ / m. 2 256kJ / m 2 258kJ / m 2 260kJ / m 2 262kJ / m 2 265kJ / m 2 276kJ / m 2 283kJ / m 2 285kJ / m 2 300kJ / m 2 305kJ / m 2 310kJ / m 2 320kJ / m 2 323kJ / m 2 325kJ / m 2 327kJ / m 2 330kJ / m2 And any value between the two adjacent values ​​mentioned above.

[0046] By adopting the above-described solution, the yield strength of the die-cast aluminum alloy in this application embodiment is above 110 MPa, which helps to prevent impact instability, and the impact toughness of the aluminum alloy is 250 kJ / m. 2 The above measures effectively prevent large castings from becoming too brittle and cracking over a large area, thus meeting the comprehensive performance requirements of aluminum alloys.

[0047] According to a second aspect of the embodiments of this application, a method for preparing a die-cast aluminum alloy is provided, comprising the following steps: Provide aluminum alloy liquid; The aluminum alloy liquid is die-cast at a cooling rate to obtain a die-cast aluminum alloy.

[0048] By adopting the above scheme and setting different cooling rates during the die casting process, the crystal structure of die-cast aluminum alloy can be effectively improved, the segregation of brittle phases can be avoided, thereby improving the impact toughness of die-cast aluminum alloy and reducing the risk of collision failure.

[0049] In die-cast aluminum alloys, the precipitation strengthening effect of each element varies under different cooling rates. For example, at a suitable cooling rate, the strengthening phase of Mg can avoid segregation at grain boundaries, thus reducing its impact on the impact toughness of the die-cast aluminum alloy. Appropriate Si content and Si at a suitable cooling rate can induce grain refinement strengthening, and the AlSi eutectic structure provides a strengthening effect. Moreover, at the same content, Si has a relatively lower impact on impact toughness compared to other elements.

[0050] In some embodiments of this application, the step of providing molten aluminum alloy includes: Aluminum alloy liquid is made from at least one of pure aluminum, aluminum-silicon alloy, aluminum-titanium alloy, pure magnesium, aluminum-manganese alloy, or aluminum-strontium alloy.

[0051] By adopting the above scheme, different metal raw materials or alloy raw materials can be selected according to different application requirements.

[0052] In some embodiments of this application, the cooling rate ranges from 100 k / s to 900 k / s. Further, the cooling rate ranges from 100 k / s to 700 k / s. Exemplarily, the cooling rate can be 100 k / s, 200 k / s, 300 k / s, 400 k / s, 500 k / s, 600 k / s, 700 k / s, or any value between two adjacent values.

[0053] By adopting the above-mentioned scheme, the cooling rate of the traditional die-casting process is extremely fast. The cooling rate of the embodiment of this application is within a suitable range, which helps to make the precipitates uniformly dispersed and avoid the precipitates from agglomerating at the grain boundaries, thereby ensuring that the die-cast aluminum alloy of the embodiment of this application has excellent yield strength and impact toughness.

[0054] In some embodiments of this application, the mold temperature range in die casting is 50°C. o C to 320 o C. For example, the mold temperature in die casting can be 50°C. o C, 80 o C, 100 o C, 120 o C, 150 o C, 180 o C, 200 o C, 2200 o C, 250 o C, 270 o C, 300 o C, 320 o C and any value between the two adjacent values ​​mentioned above.

[0055] In some embodiments of this application, the temperature of the molten aluminum alloy ranges from 660°C. o C to 730 o C. For example, the temperature of the molten aluminum alloy can be 660°C. o C, 670 o C, 680 o C, 690 o C, 700 o C, 710 o C, 720 o C, 730 o C and any value between the two adjacent values ​​mentioned above.

[0056] In some embodiments of this application, the die-casting speed in die-casting molding ranges from 2.0 m / s to 6.0 m / s. Exemplarily, the die-casting speed in die-casting molding can be 2.0 m / s, 2.5 m / s, 3.0 m / s, 3.5 m / s, 4.0 m / s, 4.5 m / s, 4.8 m / s, 5.1 m / s, 5.6 m / s, 6.0 m / s, or any value between two adjacent values ​​mentioned above.

[0057] In some embodiments of this application, the casting pressure in die casting ranges from 30 MPa to 60 MPa. Exemplarily, the casting pressure in die casting can be 35 MPa, 40 MPa, 45 MPa, 50 MPa, 55 MPa, 60 MPa, or any value between two adjacent values.

[0058] By adopting the above scheme, the cooling rate can be controlled by adjusting the mold temperature, the initial temperature of the aluminum alloy liquid before die casting, the die casting speed, and the casting pressure. When the mold temperature, the initial temperature of the aluminum alloy liquid before die casting, the die casting speed, and the casting pressure are within the above range, it helps to control the cooling rate between 100K / S and 900K / S, thereby obtaining an aluminum alloy with both good impact toughness and yield strength.

[0059] According to a third aspect of the embodiments of this application, an automotive structural component is provided, the automotive structural component comprising a die-cast aluminum alloy as described above or a die-cast aluminum alloy prepared by the aforementioned method for preparing die-cast aluminum alloy.

[0060] By adopting the above-described solution, the automotive structural components of this application embodiment include all the beneficial effects of the aforementioned die-cast aluminum alloy, which will not be repeated here. Exemplarily, automotive structural components may include, but are not limited to, the front compartment of a vehicle, the rear floor of a vehicle, door frames of a vehicle, battery pack housings, energy-absorbing boxes, etc.

[0061] According to a fourth aspect of the embodiments of this application, a vehicle is provided, the vehicle including the aforementioned automotive structural components or the aforementioned die-cast aluminum alloy.

[0062] By adopting the above solution, the vehicle in this application embodiment includes all the beneficial effects of the aforementioned automotive structural components, which will not be repeated here.

[0063] The present application will be specifically described below through specific embodiments. These embodiments are only some embodiments of the present application and are not intended to limit the present application. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0064] Example 1-1 Preparation of materials: Weigh Al, Mn, Si and Ti according to the mass proportions shown in Table 1, and preheat and dry them to ensure the dryness of the raw materials; According to the preset ratio, prepare pure aluminum, aluminum-silicon alloy AlSi20, and aluminum-titanium alloy AlTi5 for smelting. Pure aluminum is added to a smelting furnace and heated to 700°C. o C to 800 o C, fully melt pure aluminum to obtain the first melt; Aluminum-silicon alloy, aluminum-manganese alloy AlMn10 and aluminum-titanium alloy are added sequentially to the first melt, and the mixture is continued to melt and stirred evenly to obtain the second melt. The second melt is then refined, purified, and modified at a temperature controlled at 700°C. o C to 720 oC. Then, high-purity argon gas is introduced into the bottom of the second melt using a degassing rotor and stirred clockwise for 15 minutes to carry out impurity removal and degassing refining treatment. Then, the aluminum slag is removed from the furnace to obtain aluminum alloy liquid. Molten aluminum alloy is filled into a die-casting and heat-insulating equipment, and die-casting is performed at a cooling rate to obtain structural parts; wherein, the mold temperature is 250±10℃. o C. The temperature of the aluminum alloy melt is 680±5℃. o C, cooling rate is 100K / S, die casting speed is 4.5±0.3m / s, and casting pressure is 40±5MPa.

[0065] Examples 1-2 to 1-3 The difference between Examples 1-2 to 1-3 and Example 1-1 lies in the different contents of Si and Ti in the aluminum alloy. The aluminum alloys in Examples 1-2 to 1-3 are configured according to the alloying elements and mass parts in Table 1.

[0066] Comparative Examples 1-1 to 1-3 The difference between Comparative Examples 1-1 to 1-3 and Example 1-1 lies in the different contents of Si and Ti in the aluminum alloy. The aluminum alloys of Comparative Examples 1-1 to 1-3 are configured according to the alloying elements and mass parts in Table 1.

[0067] Table 1

[0068] Example 2-1 The difference from Example 1-1 is that the aluminum alloy liquid is die-cast at different cooling rates, and the die-casting process parameters are a mold temperature of 270±10℃. o C. The temperature of the aluminum alloy melt is 660±5℃. o C, cooling rate is 200 K / S, die casting speed is 5±0.3 m / s, and casting pressure is 50±5 MPa.

[0069] Examples 2-2 to 2-3 The difference between Examples 2-2 to 2-3 and Example 2-1 is that the content of Si and Ti in the aluminum alloy is different. The aluminum alloys in Examples 2-2 to 2-3 are configured according to the alloying elements and mass parts in Table 2.

[0070] Comparative Examples 2-1 to 2-2 The difference between Comparative Examples 2-1 to 2-2 and Example 2-1 lies in the different contents of Si and Ti in the aluminum alloy. The aluminum alloys of Comparative Examples 2-1 to 2-2 are configured according to the alloying elements and mass parts in Table 2.

[0071] Table 2

[0072] Example 3-1 The difference from Example 1-1 is that the aluminum alloy liquid is die-cast at different cooling rates, and the die-casting process parameters are a mold temperature of 270±10℃. o C. The temperature of the aluminum alloy melt is 680±5℃. o C, cooling rate is 300 K / S, die casting speed is 4.5±0.3 m / s, and casting pressure is 45±5 MPa.

[0073] Examples 3-2 to 3-3 The difference between Examples 3-2 to 3-3 and Example 3-1 is that the content of Si and Ti in the aluminum alloy is different. The aluminum alloys in Examples 3-2 to 3-3 are configured according to the alloying elements and mass parts in Table 3.

[0074] Comparative Examples 3-1 to 3-2 The difference between Comparative Examples 3-1 to 3-2 and Example 3-1 lies in the different contents of Si and Ti in the aluminum alloy. The aluminum alloys of Comparative Examples 3-1 to 3-2 are configured according to the alloying elements and mass parts in Table 3.

[0075] Table 3

[0076] Example 4-1 The difference from Example 1-1 is that the aluminum alloy liquid is die-cast at different cooling rates, and the die-casting process parameters are a mold temperature of 250±10℃. o C. The temperature of the aluminum alloy melt is 700±5℃. o C, cooling rate is 400 K / S, die casting speed is 5±0.3 m / s, and casting pressure is 55±5 MPa.

[0077] Examples 4-2 to 4-3 The difference between Examples 4-2 and 4-3 and Example 4-1 is that the content of Si and Ti in the aluminum alloy is different. The aluminum alloys in Examples 4-2 and 4-3 are configured according to the alloying elements and mass parts in Table 4.

[0078] Comparative Examples 4-1 to 4-2 The difference between Comparative Examples 4-1 to 4-2 and Example 4-1 lies in the different contents of Si and Ti in the aluminum alloy. The aluminum alloys of Comparative Examples 4-1 to 4-2 are configured according to the alloying elements and mass parts in Table 4.

[0079] Table 4

[0080] Example 5-1 The difference from Example 1-1 is that the aluminum alloy liquid is die-cast at different cooling rates, and the die-casting process parameters are a mold temperature of 230±10℃. o C. The temperature of the aluminum alloy melt is 690±5℃.o C, cooling rate is 500 K / S, die casting speed is 4.5±0.3 m / s, and casting pressure is 45±5 MPa.

[0081] Examples 5-2 to 5-3 The difference between Examples 5-2 and 5-3 and Example 5-1 is that the content of Si and Ti in the aluminum alloy is different. The aluminum alloys in Examples 5-2 and 5-3 are configured according to the alloying elements and mass parts in Table 5.

[0082] Comparative Examples 5-1 to 5-2 The difference between Comparative Examples 5-1 to 5-2 and Example 5-1 lies in the different contents of Si and Ti in the aluminum alloy. The aluminum alloys of Comparative Examples 5-1 to 5-2 are configured according to the alloying elements and mass parts in Table 5.

[0083] Table 5

[0084] Example 6-1 The difference from Example 1-1 is that the aluminum alloy liquid is die-cast at different cooling rates, and the die-casting process parameters are a mold temperature of 200±10℃. o C. The temperature of the aluminum alloy melt is 700±5℃. o C, cooling rate is 600 K / S, die casting speed is 4±0.3 m / s, and casting pressure is 50±5 MPa.

[0085] Examples 6-2 to 6-3 The difference between Examples 6-2 and 6-3 and Example 6-1 is that the content of Si and Ti in the aluminum alloy is different. The aluminum alloys in Examples 6-2 and 6-3 are configured according to the alloying elements and mass parts in Table 6.

[0086] Comparative Examples 6-1 to 6-2 The difference between Comparative Examples 6-1 to 6-2 and Example 6-1 lies in the different contents of Si and Ti in the aluminum alloy. The aluminum alloys of Comparative Examples 6-1 to 6-2 are configured according to the alloying elements and mass parts in Table 6.

[0087] Table 6

[0088] Example 7-1 The difference from Example 1-1 is that the aluminum alloy liquid is die-cast at different cooling rates, and the die-casting process parameters are a mold temperature of 170±10℃. o C. The temperature of the aluminum alloy melt is 700±5℃. o C, cooling rate is 700 K / S, die casting speed is 5±0.3 m / s, and casting pressure is 45±5 MPa.

[0089] Examples 7-2 to 7-3 The difference between Examples 7-2 and 7-3 and Example 7-1 is that the content of Si and Ti in the aluminum alloy is different. The aluminum alloys in Examples 7-2 and 7-3 are configured according to the alloying elements and mass parts in Table 7.

[0090] Comparative Examples 7-1 to 7-2 The difference between Comparative Examples 7-1 to 7-2 and Example 7-1 lies in the different contents of Si and Ti in the aluminum alloy. The aluminum alloys of Comparative Examples 7-1 to 7-2 are configured according to the alloying elements and mass parts in Table 7.

[0091] Table 7

[0092] Example 8-1 The difference from Example 1-1 is that the aluminum alloy liquid is die-cast at different cooling rates, and the die-casting process parameters are a mold temperature of 140±10℃. o C. The temperature of the aluminum alloy melt is 700±5℃. o C, cooling rate is 800 K / S, die casting speed is 5±0.3 m / s, and casting pressure is 40±5 MPa.

[0093] Examples 8-2 to 8-3 The difference between Examples 8-2 and 8-3 and Example 8-1 is that the content of Si and Ti in the aluminum alloy is different. The aluminum alloys in Examples 8-2 and 8-3 are configured according to the alloying elements and mass parts in Table 8.

[0094] Comparative Examples 8-1 to 8-2 The difference between Comparative Examples 8-1 to 8-2 and Example 8-1 is that the content of Si and Ti in the aluminum alloy is different. The aluminum alloys of Comparative Examples 8-1 to 8-2 are configured according to the alloying elements and mass parts in Table 8.

[0095] Table 8

[0096] Example 9-1 The difference from Example 1-1 is that the aluminum alloy liquid is die-cast at different cooling rates, and the die-casting process parameters are a mold temperature of 100±10℃. o C. The temperature of the aluminum alloy melt is 700±5℃. o C, cooling rate is 900 K / S, die casting speed is 5±0.3 m / s, and casting pressure is 45±5 MPa.

[0097] Comparative Example 9-1 The difference between Comparative Example 9-1 and Example 9-1 is that the content of Si and Ti in the aluminum alloy is different. The aluminum alloy of Comparative Example 9-1 is prepared according to the alloying elements and mass parts in Table 9.

[0098] Table 9

[0099] Performance testing: (1) Tensile test: The tensile strength, yield strength, and elongation of the material were tested according to GB / T 228.1-2010 Metallic materials, tensile testing—Part 1: Test at room temperature. Tensile test bars (diameter 6.4mm × gauge length 50mm) were tested for tensile properties using a CMT5105 electronic universal testing machine with a gauge length of 50mm and a loading rate of 2mm / min. Measurement data were recorded. (2) Impact toughness test: A pendulum impact testing machine was used. The pendulum of the machine impacts and passes through the sample at a certain speed. The energy consumed by the pendulum angle was measured to evaluate the impact resistance of the material. The pendulum pre-tilt angle was 150°. The test material was an unnotched sample with a length × width × thickness of 55 × 10 mm × 4 mm.

[0100] The test results are shown in Table 10. Table 10

[0101] Comparing the embodiments with the comparative examples, the mass percentage of Si in the embodiments satisfies Equation I, while the mass percentage of Si in the comparative examples is outside the range of Equation I. Referring to Table 10, it can be seen that, compared with the comparative examples, the embodiments exhibit superior yield strength and impact toughness. That is, within a suitable range, the yield strength of the aluminum alloy in the embodiments is greater than or equal to 105 MPa, and the impact toughness is greater than or equal to 250 kJ / m. 2 However, the yield strength and impact toughness of the aluminum alloy in comparison cannot simultaneously meet the performance requirements.

[0102] Compared with Examples 8-1 to 8-3 and Example 9-1, when the cooling rate reaches 800 K / S or 900 K / S, the impact toughness of aluminum alloy is significantly reduced when the Si content is less than 7.5%. This is mainly due to the low forming capacity of the material and the significantly larger shrinkage rate, which leads to a significant increase in defects in the aluminum alloy and a deterioration in the impact toughness of the aluminum alloy.

[0103] Figure 5 This is a metallographic image of the aluminum alloy of Embodiment 1-1 of this application, by... Figure 5 It can be seen that the metallographic structure is uniformly distributed and there is no obvious aggregation of brittle phases. When subjected to impact load, it can uniformly transmit stress, effectively avoid local stress concentration, and has good impact toughness. Figure 6 This is a metallographic image of the aluminum alloy of Embodiment 7-1 of this application, by... Figure 6 It can be seen that the metallographic structure is also uniformly distributed, with no obvious aggregation of brittle phases. When subjected to impact load, it can uniformly transmit stress, effectively avoid local stress concentration, and has good impact toughness.

[0104] Figure 7 This is a metallographic image of the aluminum alloy in Comparative Example 1-1 of this application. Figure 8 These are metallographic images of the aluminum alloys in Comparative Examples 1-4 of this application, by... Figure 7-8 It can be seen that the metallographic structure is unevenly distributed, with obvious aggregation of brittle phases, and the size difference of α-Al is large in the casting, which disrupts the continuity of the material and easily causes local stress concentration. The aluminum alloy with this morphology has poor impact resistance.

[0105] The foregoing has provided a detailed description of the die-cast aluminum alloy and its preparation method, automotive structural parts, and vehicles provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A die-cast aluminum alloy, characterized in that, The die-cast aluminum alloy includes Si; The mass percentage of Si, Wt(Si)%, satisfies the formula shown in Equation I: Wt(Si) = 11.33 - 0.0219V 3 +0.2792V 2 -1.4403V±1 type I; Where V is the ratio of the cooling rate to 100, and the unit of cooling rate is K / S.

2. The die-cast aluminum alloy according to claim 1, characterized in that, The mass percentage of Si, Wt(Si)%, satisfies the formula shown in Equation III: Wt(Si) = 11.33 - 0.0219V 3 +0.2792V 2 -1.4403V±0.7Form III.

3. The die-cast aluminum alloy according to claim 1 or 2, characterized in that, The value of V ranges from 1 to 9; Preferably, the value of V ranges from 1 to 7.

4. The die-cast aluminum alloy according to any one of claims 1 to 3, characterized in that, The Si content in the die-cast aluminum alloy is 6% to 11% by mass.

5. The die-cast aluminum alloy according to any one of claims 1 to 4, characterized in that, The die-cast aluminum alloy also includes Ti; The mass percentage of Ti, Wt(Ti)%, satisfies the formula shown in Equation II: Wt(Ti) ​​= 0.2012e -0.177(V) ±0.02 Formula II.

6. The die-cast aluminum alloy according to claim 5, characterized in that, The mass percentage of Ti, Wt(Ti)%, satisfies the formula shown in Equation IV: Wt(Ti) ​​= 0.2012e -0.177(V) ±0.015 Form IV.

7. The die-cast aluminum alloy according to claim 5 or 6, characterized in that, The mass percentage of Ti in the die-cast aluminum alloy is 0.02% to 0.17%.

8. The die-cast aluminum alloy according to any one of claims 1 to 7, characterized in that, The die-cast aluminum alloy also includes functional elements; The functional element includes at least one of Mn, Mg, Sr, Cu, Fe, and Zn.

9. The die-cast aluminum alloy according to any one of claims 1 to 8, characterized in that, The yield strength of the die-cast aluminum alloy is greater than or equal to 105 MPa. The impact toughness of the die-cast aluminum alloy is greater than or equal to 250 kJ / m. 2 ; Preferably, the yield strength of the die-cast aluminum alloy is greater than or equal to 120 MPa; Preferably, the impact toughness of the die-cast aluminum alloy is greater than or equal to 260 kJ / m. 2 .

10. A method for preparing a die-cast aluminum alloy, characterized in that, The method for preparing the die-cast aluminum alloy as described in any one of claims 1 to 9 comprises the following steps: Provide aluminum alloy liquid; The aluminum alloy liquid is die-cast at a cooling rate to obtain the die-cast aluminum alloy.

11. The method for preparing die-cast aluminum alloy according to claim 10, characterized in that, The cooling rate ranges from 100 K / S to 900 K / S; Preferably, the cooling rate ranges from 100 K / S to 700 K / S.

12. The method for preparing die-cast aluminum alloy according to claim 10, characterized in that, The mold temperature range in the die casting process is 50°C. o C to 320 o C; and / or The temperature range of the molten aluminum alloy is 660°C. o C to 730 o C; and / or The die-casting speed in the die-casting process ranges from 2.0 m / s to 6.0 m / s; and / or The casting pressure in the die casting process is 30 MPa to 60 MPa.

13. An automotive structural component, characterized in that, The automotive structural component includes a die-cast aluminum alloy prepared by any one of claims 1 to 9 or by any one of claims 10 to 12.

14. A vehicle, characterized in that, The vehicle includes the automotive structural components as described in claim 13 or the die-cast aluminum alloy as described in any one of claims 1 to 9.

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