A high-strength and high-damping cast aluminum-silicon alloy and its preparation method

Abstract

The present invention provides a high-strength and high-damping cast aluminum-silicon alloy, which, by mass percentage, comprises: Si in an amount of 7.5-8.5, Mg in an amount of 1.0-1.5, Sn in an amount of 1.5-2.5, Ti in an amount of 0.10-0.15, Zr in an amount of 0-0.20, Sr in an amount of 0.01-0.02, and the balance being aluminum. The present invention also provides a preparation method of the high-strength and high-damping cast aluminum-silicon alloy for manufacturing the high-strength and high-damping cast aluminum-silicon alloy as described above, and the steps are as follows: proportioning and preheating the raw materials to 200°C, and the raw materials can be single substances or master alloys of various alloying elements; preparing the furnace body; adding aluminum ingots until completely melted; adding silicon blocks until completely melted and stirring evenly; adding other ingredients, and finally adding Al-Sr master alloy and stirring evenly; refining; casting and molding; heat treatment. The present invention makes the Mg2Si and Mg2Sn phases be finely and dispersedly distributed in the aluminum alloy matrix and makes the eutectic Si phase degenerate and spheroidize, thereby improving the damping performance and strength of the aluminum alloy.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials and new energy, and particularly relates to an aluminum-silicon alloy with better damping performance and a preparation method thereof. Background Art

[0002] At present, damping, also known as "internal friction", refers to the phenomenon that mechanical vibration energy dissipation occurs due to the inherent reasons of the system itself when the material vibrates under the action of an externally applied stress. During the vibration process, the material usually converts mechanical energy into internal energy through changes in its internal structure and dissipates it into the material and the environment, thereby reducing vibration and noise. This ability of the material to consume vibration energy through its own conversion is the damping performance of the material. High-damping materials have extensive application requirements in the fields of national defense, aerospace, transportation, etc., and can improve the stability, safety, concealment, and comfort of components or equipment. They are one of the urgent material requirements in the development of aerospace, rail transit, and modern industry.

[0003] Currently, commonly used high-damping metal materials include alloy series such as Mn-Cu, Ni-Ti, Zn-Al, etc. Among them, the Zn-Al alloy has always been a hot topic in the research field of high-damping metal materials due to its advantages such as light weight, easy forming and processing, and heat treatment strengthening. At present, Zn-Al alloys with high damping have been developed, such as Zn-27Al, etc. However, since its composition is mainly Zn with a relatively large density, the density of the alloy is relatively high, about 6.16 g / cm 3 .

[0004] Considering the requirements of lightweight and low cost, high-damping aluminum alloys have a broader application prospect in the field of vibration reduction and noise reduction. However, although aluminum alloys have the characteristics of light weight and high strength, the intrinsic damping performance of Al is relatively low, and the damping value Q of aluminum alloys at room temperature and 1 Hz -1 usually difficult to exceed 0.02, which limits the development of aluminum alloys in the field of damping vibration reduction.

[0005] Therefore, how to obtain an aluminum-silicon alloy with better damping performance is an urgent problem to be solved in the high-strength casting industry. Summary of the Invention

[0006] One main object of the present invention is to overcome at least one defect of the above-mentioned prior art, and provide a high-strength and high-damping cast aluminum-silicon alloy capable of obtaining better damping performance and a preparation method thereof.

[0007] To achieve the above-mentioned invention object, the present invention adopts the following technical solutions:

[0008] According to one aspect of the present invention, there is provided a high-strength and high-damping cast aluminum-silicon alloy, which includes, by mass percentage:

[0009] The amount of Si is 7.5 - 8.5 wt.%, the amount of Mg is 1.0 - 1.5 wt.%, the amount of Sn is 1.5 - 2.5 wt.%, the amount of Ti is 0.10 - 0.15 wt.%, the amount of Zr is 0 - 0.20 wt.%, the amount of Sr is 0.01 - 0.02 wt.%, and the balance is aluminum.

[0010] According to a specific embodiment of the present invention, the chemical formula of the high-strength and high-damping cast aluminum-silicon alloy is: AlSi8Mg 1.5 Sn2Ti 0.15 Or AlSi8Mg 1.5 Sn2Ti 0.15 Zr 0.2 。

[0011] According to another aspect of the present invention, a method for preparing a high-strength and high-damping cast aluminum-silicon alloy is provided, which is used to manufacture the high-strength and high-damping cast aluminum-silicon alloy as described above. The steps are as follows:

[0012] Step 1, proportion the raw materials and preheat them to 200 °C. The raw materials can be the single elements or master alloys of various alloying elements;

[0013] Step 2, prepare the furnace body;

[0014] Step 3, add aluminum ingots until completely melted;

[0015] Step 4, add silicon blocks until completely melted and then stir evenly;

[0016] Step 5, add other ingredients, and finally add Al-Sr master alloy and stir evenly;

[0017] Step 6, refine;

[0018] Step 7, cast and form;

[0019] Step 8, heat treatment.

[0020] According to a specific embodiment of the present invention, in step 2, it includes: cleaning the furnace body, adding ZnO coating and preheating the furnace body.

[0021] According to a specific embodiment of the present invention, in step 3, heat to 680 - 700 °C.

[0022] According to a specific embodiment of the present invention, in step 4, maintain the temperature in step 3 until the silicon is completely melted and then stir for 2 - 3 minutes.

[0023] According to a specific embodiment of the present invention, in step 6, the refining temperature is 700 - 730 °C, and the refining time is controlled within 20 ± 1 minute.

[0024] According to a specific embodiment of the present invention, in step 7, after removing the dross, casting is carried out, and the temperature of the molten liquid is 720 ± 5 °C.

[0025] According to a specific embodiment of the present invention, in step 8, it includes solution treatment and aging treatment; wherein, the solution treatment is single-stage solution treatment at 505 °C for 14 hours or multi-stage solution treatment at 505 °C for 5 hours plus 535 °C for 5 hours; the aging treatment is aging treatment at 155 °C for 12 hours or aging treatment at 165 °C for 8 hours.

[0026] According to a specific embodiment of the present invention, after the solution treatment of the alloy, it is cooled in water at 60 °C, and after the aging treatment of the alloy, it is cooled in air.

[0027] As can be seen from the above technical solutions, the advantages and positive effects of the high-strength and high-damping cast aluminum-silicon alloy and its preparation method of the present invention are as follows:

[0028] By regulating the ratio of Sn and Mg in the present invention, the Mg2Si and Mg2Sn phases are finely and dispersedly distributed in the aluminum alloy matrix and the eutectic Si phase is spheroidized, the amount of Mg2Sn phase is increased and the β-Sn phase is reduced, achieving the effect of simultaneously improving the damping performance and strength of the aluminum alloy, and adding appropriate amounts of Ti and Zr to the aluminum alloy to further enhance the damping performance and / or strength of the aluminum alloy, so as to achieve high-strength and high-damping performance without increasing the cost by adding precious metals. Description of the Drawings

[0029] Figure 1 is a metallographic structure picture of a high-strength and high-damping cast aluminum-silicon alloy proposed by the present invention.

[0030] Figure 2 is a stress-strain curve graph of a high-strength and high-damping cast aluminum-silicon alloy proposed by the present invention.

[0031] Figure 3 is a DMA damping test result graph of a high-strength and high-damping cast aluminum-silicon alloy proposed by the present invention. Detailed Embodiments

[0032] Now, the exemplary embodiments will be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; on the contrary, these embodiments are provided so that the present invention will be thorough and complete, and the concept of the exemplary embodiments will be fully conveyed to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed descriptions will be omitted.

[0033] The high-strength and high-damping cast aluminum-silicon alloy of the present invention comprises six alloying elements, namely Al, Si, Mg, Sn, Ti and Zr, and uses an Al-Sr master alloy as a refiner. The so-called "high strength" means that the tensile strength that the material can reach is ≥300 MPa, and the so-called "high damping" means that the damping performance Q -1 (tanδ) of the material can reach ≥0.03.

[0034] The strength of the alloy of the present invention is closely related to the composition of the alloy. If the alloy needs to further improve its strength, the contents of Si and Sn can be further reduced, and the contents of Mg, Ti and Zr can be increased. If the damping performance needs to be further improved, the Sn content of the alloy can be increased. However, excessive Sn content may result in the formation of β-Sn phase, which will affect the mechanical properties of the alloy. If the elongation of the alloy needs to be improved, a relatively low aging temperature and a relatively short holding time can be adopted, such as 155°C for 9-12 h. A small amount of rare earth elements can be added to the alloy to improve its mechanical properties and damping performance, but a more precise casting process needs to be adopted to prevent a large number of casting defects caused by alloy oxidation.

[0035] The microstructure of the alloy is observed by a ZEISS EVO MA25 type scanning electron microscope. The tensile strength and elongation after fracture of the alloy are obtained by room temperature tensile test according to GB / T228.1-2010. The damping performance is tested by a DMA850 type dynamic thermomechanical analyzer. The test temperature is 25°C and the frequency is 1 Hz. The damping loss factor tanδ is used as the damping performance index.

[0036] In the preparation method of the present invention, Sn and Mg are added to the Al-Si cast aluminum alloy to form a dispersed and fine distribution of Sn phase in the aluminum alloy matrix, so as to improve the damping performance of the aluminum alloy; an appropriate amount of Ti and Zr are added to further strengthen the aluminum alloy matrix. Through the exploration of the heat treatment system, the optimal solution heat treatment and aging system are obtained. Through the reasonable selection of the types and contents of the above elements and the optimization of heat treatment, the damping performance and mechanical properties of the cast aluminum alloy are balanced.

[0037] Among them, the amount of Sn added is 1.5-2.5 wt.%, the amount of Mg added is 1.0-1.5 wt.%, the amount of Ti added is 0.10-0.15%, the amount of Zr added is 0-0.20 wt.%, and the amount of Sr added is 0.01-0.02 wt.%. The preparation method of the present invention first prepares raw materials according to the ratio.

[0038] Then, clean the furnace body and apply ZnO coating, and preheat the furnace body. Meanwhile, preheat the metal mold to 200 °C. Then add aluminum ingots into the furnace and heat them up to 680 - 700 °C with the furnace until they are completely melted. Use an electric resistance furnace or intermediate frequency induction furnace to melt the mixed furnace charge of Al, Si, and Mg, add Si between 680 °C and 700 °C, stir for 2 - 3 minutes after complete melting and hold for a period of time. Heat up to 730 - 740 °C and add Al-5Ti, stir evenly during the process and then add Al-10Zr, cool down to 680 - 690 °C and add Mg, stir evenly during the process and then add Al-50Sn, heat up to 720 - 730 °C and add Al-10Sr, stir for 3 - 4 minutes after it is completely melted.

[0039] Refining: When the temperature is between 700 - 730 °C, introduce argon gas into the smelting body for refining. After refining for 20 minutes, let it stand for a period of time, remove the floating slag and then carry out pouring. After refining, pour the molten metal liquid into the French standard and national standard metal molds preheated to 200 °C at a temperature of 715 - 725 °C.

[0040] Maintain the melt temperature at 700 - 750 °C, press the Al-Sn master alloy preheated to 200 - 300 °C into the center of the molten pool with a bell jar, hold for 3 - 5 minutes, then skim the slag and cast to obtain the required high-strength and high-damping cast aluminum alloy. It is necessary to add pure Si and pure Mg at 680 - 700 °C, melt Al-Ti and Al-Zr into the gate runner at 730 - 740 °C, melt Al-Sr into the gate runner at 720 - 730 °C, introduce argon gas for refining during the casting process, and finally carry out casting at 715 - 725 °C.

[0041] Perform heat treatment on the alloy. Solution treatment can be carried out at 505 °C for 14 h / 505 °C for 5 h + 535 °C for 5 h. After solution treatment, put it into water cooling with the water temperature at 60 °C. Use the aging method of 155 °C for 12 h / 165 °C for 8 h, and then air cool to room temperature.

[0042] On the other hand, the present invention provides a high-strength and high-damping cast aluminum-silicon alloy, which is prepared by the preparation method described above. The properties of the alloy include: the tensile strength is 280 - 340 MPa. At 25 °C and 1 Hz, using the single-cantilever mode to measure the damping sheet with dimensions of 40 mm × 10 mm × 2 mm, its damping performance, the damping loss factor tanδ is 0.079 - 0.093. If it is a damping sheet with dimensions of 40 mm × 10 mm × 1 mm, its damping loss factor tanδ is 0.034 - 0.040.

[0043] The chemical formula of the alloy is: AlSi8Mg 1.5 Sn2Ti 0.15Or AlSi8Mg 1.5 Sn2Ti 0.15 Zr 0.2 By reasonably selecting the types and contents of elements, the present invention improves the damping performance of Al-Si series cast aluminum alloys on the premise that the plasticity and casting fluidity of the alloys are basically equivalent, and balances the mechanical properties of the alloys. The present invention does not contain rare and precious metals, nor does it require changing the existing aluminum alloy melting and casting equipment.

[0044] Sn can be used as high internal friction particles in Al-Si-Mg alloys and can form more interfaces to improve the damping performance of the alloys. However, pure Sn has low strength, and the β-Sn phase formed in Al-Si-Mg alloys will significantly reduce the mechanical properties of the alloys. By increasing the content of Mg in the alloys and controlling the ratio of Mg and Sn in the alloys, the second-phase particles Mg2Sn are formed in the alloy matrix, which can reduce the adverse effects of the β-Sn phase on the alloy strength, and the second-phase particles Mg2Sn can also improve the damping performance.

[0045] Since the composition of Al-Si-Mg-Sn alloys is different from that of Al-Si-Mg alloys, and the formation temperatures of the Mg2Sn phase and the originally existing Mg2Si phase are inconsistent, it is difficult to disperse and precipitate the second phase in the alloy matrix by using the original heat treatment system to achieve a good strengthening effect, and it may also cause the alloy to overheat and significantly reduce the mechanical properties of the alloy. Therefore, it is necessary to optimize the heat treatment system of the alloy to obtain an alloy with more balanced strength and plasticity.

[0046] Example 1: AlSi8Mg 1.5 Sn2Ti 0.15 alloy

[0047] A high-strength and high-damping cast aluminum-silicon alloy consists of the following components in mass percentage: the mass percentage of Si is 8.0%, the mass percentage of Mg is 1.5%, the mass percentage of Sn is 2.0%, the mass percentage of Ti is 0.15%, and the mass percentage of Sr is 0.02%. The balance is Al and inevitable impurities such as Fe. Prepare the alloy according to the composition listed in Example 1, melt pure aluminum, pure Si, pure Mg, Al-50Sn master alloy, Al-5Ti master alloy, and Al-10Sr master alloy in an electric resistance furnace or an intermediate frequency induction furnace, control the melt temperature at 700-750 °C, add pure Si and pure Mg at 680-700 °C during the process, melt Al-Ti into the gating runner at 730-740 °C, melt Al-Sr into the gating runner at 720-730 °C, add Al-50Sn master alloy blocks at 200-300 °C, and then refine by introducing argon gas during the casting process, and finally cast at 715-725 °C.

[0048] Afterwards, heat treatment was carried out on the alloy, adopting a solution treatment regime of 505°C for 5 h + 535°C for 5 h and an aging treatment regime of 155°C for 12 h.

[0049] The room-temperature tensile strength and elongation after fracture of the alloy were tested in accordance with GB / T 228.1-2010 of the national standard; the damping performance of the alloy was tested using a dynamic thermomechanical analyzer DMAQ850, the test temperature was 25°C, the frequency was 1 Hz, and the damping loss factor tanδ was used as the damping performance index. The results are shown in Table 1.

[0050] Table 1 AlSi8Mg 1.5 Sn2Ti 0.15 Room-temperature mechanical properties and damping performance of the alloy

[0051]

[0052] Example 2: AlSi8Mg 1.5 Sn2Ti 0.15 Zr 0.2 Alloy

[0053] A high-strength and high-damping cast aluminum-silicon alloy consists of the following components by mass percentage: the mass percentage of Si is 8.0%, the mass percentage of Mg is 1.5%, the mass percentage of Sn is 2.0%, the mass percentage of Ti is 0.15%, the mass percentage of Zr is 0.2%, and the mass percentage of Sr is 0.02%. The balance is Al and unavoidable impurities such as Fe. The alloy was prepared according to the component ratio listed in Example 2. Pure aluminum, pure Si, pure Mg, Al-50Sn master alloy, Al-5Ti master alloy, Al-10Zr master alloy, and Al-10Sr master alloy were melted in an electric resistance furnace or an intermediate frequency induction furnace. The melt temperature was controlled at 700-750°C. During the process, pure Si and pure Mg were added at 680-700°C, Al-Ti and Al-Zr were melted into the gating runner at 730-740°C, Al-Sr needed to be melted into the gating runner at 720-730°C, and Al-50Sn master alloy blocks were added at 200-300°C. Afterwards, argon gas was introduced for refining during the pouring process, and finally pouring was carried out at 715-725°C.

[0054] Afterwards, heat treatment was carried out on the alloy, adopting a solution treatment regime of 505°C for 5 h + 535°C for 5 h and an aging treatment regime of 165°C for 8 h.

[0055] The room-temperature tensile strength and elongation after fracture of the alloy were tested in accordance with GB / T 228.1-2010 of the national standard; the damping performance of the alloy was tested using a dynamic thermomechanical analyzer DMAQ850, the test temperature was 25°C, the frequency was 1 Hz, and the damping loss factor tanδ was used as the damping performance index. The results are shown in Table 2.

[0056] Table 2 AlSi8Mg 1.5 Sn2Ti 0.15 Zr 0.2 Room temperature mechanical properties and damping properties of the alloy

[0057]

[0058] The above has introduced in detail a high-strength and high-damping cast aluminum alloy and its preparation method provided by the embodiments of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes.

[0059] Regarding the performance comparison of the present invention, compared with the currently applied aluminum alloy structural materials such as ZL101A and ZL114A, this alloy meets their national standard mechanical property indicators and at the same time has damping properties, and is a new type of alloy with integrated structure and function. The following Table 3 is the reference of the national standard performance of common cast Al-Si series alloys:

[0060] Table 3 Reference of relevant mechanical properties of common cast Al-Si alloys by permanent mold casting

[0061]

[0062] Among the alloy systems with relatively high damping properties in current light alloys, through the optimization of the composition and heat treatment system, this alloy has a tensile strength > 300 MPa and a room temperature damping of about 0.030 - 0.040 under the condition of density < 3 g·cm -3 , showing significant advantages compared with other damping alloys. The following Table 4 is the comparison of damping and mechanical properties of common light alloys:

[0063] Table 4 Reference of damping and mechanical properties of common light alloys

[0064]

[0065] The optimization of the heat treatment system in this alloy system also plays a key role in improving the comprehensive performance of the alloy. The following Table 5 is the comparison of the mechanical properties of the alloy in the as-cast, solution-treated, and aged states:

[0066] Table 5 Comparison of mechanical properties of Al-8Si-1.5Mg-2Sn-0.15Ti-0.2Zr alloy in different states

[0067] Status Tensile strength (MPa) Yield strength (MPa) Elongation (%) Hardness (HB) As-cast 170 113 3.0 75.8 Solution-treated 243 162 5.5 85.6 Aged 333 278 3.0 114

[0068] Such as Figures 1 to 3As shown, compared with the conventional hypoeutectic Al-Si-Mg alloy, the alloy composition of the present invention has better damping performance, and its damping value is increased by 55% - 85%. It can have a better vibration reduction and noise reduction effect in the application of vibration reduction components such as bogie components and brake system components in aerospace and rail transit. Compared with the commonly used Zn-Al damping alloy at present, while having comparable damping performance, its density < 3 g·cm -3 , and it has significant advantages in the lightweight of mechanical parts such as gears, bearings, and transmission components.

[0069] Those of ordinary skill in the art to which the present invention pertains should understand that the specific structures and process procedures shown in the above specific implementation part are merely exemplary and not restrictive. Moreover, those of ordinary skill in the art to which the present invention pertains can combine the various technical features shown above in various possible ways to form new technical solutions, or make other modifications, and all fall within the scope of the present invention.

Claims

1. A high-strength and high-damping cast aluminum-silicon alloy, characterized in that, By mass percentage, it includes: The amount of Si is 7.5 - 8.5 wt.%, the amount of Mg is 1.0 - 1.5 wt.%, the amount of Sn is 1.5 - 2.5 wt.%, the amount of Ti is 0.10 - 0.15 wt.%, the amount of Zr is 0 - 0.20 wt.%, the amount of Sr is 0.01 - 0.02 wt.%, and the balance is aluminum; The preparation method of the high-strength and high-damping cast aluminum-silicon alloy includes solution treatment and aging treatment; wherein, the solution treatment is single-stage solution treatment at 505°C for 14 hours or multi-stage solution treatment at 505°C for 5 hours plus 535°C for 5 hours; the aging treatment is aging treatment at 155°C for 12 hours or aging treatment at 165°C for 8 hours.

2. The high-strength and high-damping cast aluminum-silicon alloy according to claim 1, wherein: The chemical formula of the high-strength and high-damping cast aluminum-silicon alloy is: AlSi8Mg 1.5 Sn2Ti 0.15 Or AlSi8Mg 1.5 Sn2Ti 0.15 Zr 0.2 , and the mass percentage of Sr is 0.02%.

3. A preparation method of a high-strength and high-damping cast aluminum-silicon alloy, characterized in that, For manufacturing the high-strength and high-damping cast aluminum-silicon alloy as described in Claim 1 or 2, the steps are as follows: Step 1, proportion the raw materials and preheat them to 200°C. The raw materials are single elements or master alloys of various alloying elements. Step 2, prepare the furnace body. Step 3, add aluminum ingots until completely melted. Step 4, add silicon blocks until completely melted and then stir evenly. Step 5, add other ingredients, and finally add Al-Sr master alloy and stir evenly. Step 6, refine. Step 7, cast into shape. Step 8, heat treatment, including solution treatment and aging treatment; wherein, the solution treatment is single-stage solution treatment at 505°C for 14 hours or multi-stage solution treatment at 505°C for 5 hours plus 535°C for 5 hours; the aging treatment is aging treatment at 155°C for 12 hours or aging treatment at 165°C for 8 hours.

4. The preparation method of the high-strength and high-damping cast aluminum-silicon alloy according to claim 3, characterized in that: In Step 2, it includes: cleaning the furnace body, adding ZnO coating and preheating the furnace body.

5. The preparation method of the high-strength and high-damping cast aluminum-silicon alloy according to claim 4, characterized in that: In Step 3, heat to 680 - 700°C.

6. The preparation method of the high-strength and high-damping cast aluminum-silicon alloy according to claim 5, characterized in that: In Step 4, maintain the temperature in Step 3 until the silicon is completely melted and then stir for 2 - 3 minutes.

7. The preparation method of the high-strength and high-damping cast aluminum-silicon alloy according to claim 6, characterized in that: In Step 6, the refining temperature is 700 - 730°C, and the refining time is controlled within 20 ± 1 minute.

8. The preparation method of the high-strength and high-damping cast aluminum-silicon alloy according to claim 7, characterized in that: In Step 7, remove the dross and then cast. The melt temperature is 720 ± 5°C.

9. The preparation method of the high-strength and high-damping cast aluminum-silicon alloy according to claim 8, wherein: After the alloy solution treatment, it is cooled in water at 60°C, and after the alloy aging treatment, it is cooled in air.

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