Cast aluminum alloy with high elongation and preparation method

Abstract

The invention discloses a cast aluminum alloy with high elongation and a preparation method thereof, and the aluminum alloy comprises the following raw materials by weight percent: 6-10% of Si, 0.1-0.6% of Mn, 0.15-0.6% of Fe, and the balance of Al and inevitable impurities. According to the technical scheme, the alloy elements added to the alloy are few in variety, the content of auxiliary elements is low, and the price controllability is good; in a casting state, the steel has very excellent ductility and medium strength; heat treatment is not needed, the performance requirements of parts can be met in a casting state, and energy is saved; the method has high inclusion degree on internal defects of cast ingots, and high toughness of each area of a large-size casting can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of alloys, and in particular relates to a casting aluminum alloy with high elongation and a preparation method thereof. Background Art

[0002] With the rapid development of the new energy vehicle industry, large-scale integrated die-casting has flourished, that is, the original dozens to hundreds of parts of the car are integrated and designed and formed into a large casting through large die-casting machines. Integrated die-casting greatly reduces manufacturing costs, reduces the weight of the body structure, improves the overall rigidity of the car, and simplifies the automobile production line and process. Traditional low-pressure casting aluminum alloy structural parts achieve performance requirements through heat treatment (high temperature solid solution + low temperature aging). However, on the one hand, the size of the integrated die-casting is too large, and the heat treatment process is prone to deformation and warping. On the other hand, a certain number of bubbles will inevitably condense inside the large die-casting, and surface bubbling defects will be formed after heat treatment. Although the dimensional accuracy and defects can be improved to a certain extent by shaping means, it will also increase the scrap rate. Therefore, the development of heat-treatment-free die-casting aluminum alloy materials developed with the rise of integrated die-casting has become one of the key technologies of integrated die-casting. In order to maintain the fluidity requirements of large-scale integrated die-casting alloys, the existing heat-treatment-free alloys are mainly based on the Al-Si alloy system. Most of them use rare earth additions or one or more of the IV-VII transition elements (Mo, Zr, V, Cr, Ti, Ni) to improve the yield strength of the alloy. The alloys mainly examine strength and elongation indicators.

[0003] Automotive structural parts represented by shock absorber supports usually require extremely high elongation, but there are not many alloys in the commonly used cast aluminum alloys that can meet the performance requirements of medium strength and high elongation and do not need to be strengthened by heat treatment. Chinese invention patent CN104630578A discloses a preparation method of a high-plasticity cast aluminum alloy, which adds 0.01-1.0% RE elements, and the elongation reaches 18% after T6 heat treatment, but rare earth elements are expensive, which increases production costs, and there is no performance comparison in the cast state; Chinese invention patent CN114438380A discloses a high-toughness Al-Si cast aluminum alloy and its preparation method, which also obtains a uniform and dense microstructure by adding rare earth La+Ce combined with pressure casting, thereby achieving the effect of improving mechanical properties.

[0004] The development of large-scale integrated super-large-size castings has brought great challenges to the die-casting process. Due to the huge differences in filling and solidification conditions, the internal quality of different areas of the casting cannot reach exactly the same level, such as the proximal and distal ends of large-scale integrated die castings, the easy-to-form area and the difficult-to-form area, the slag bag layout area and the distal end without slag bags, etc. The distribution of hole defects inside the casting is quite different, and the performance of these locations, especially the elongation, is also quite different; the existing alloys face a serious problem in the application process, that is, the performance of the castings shows a large fluctuation with the internal quality difference, and the stability of batch products is also relatively poor.

[0005] Therefore, in view of the above technical problems, it is necessary to provide a cast aluminum alloy with high elongation and a preparation method thereof.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0007] The object of the present invention is to provide a casting aluminum alloy with high elongation and a preparation method thereof.

[0008] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0009] The raw material composition of the cast aluminum alloy with high elongation includes: 6-10wt.% Si, 0.1-0.6wt.% Mn, 0.15-0.6wt.% Fe, and the balance is Al and inevitable impurities.

[0010] In one or more embodiments of the present invention, V is further comprised between 0 and 0.3%.

[0011] In one or more embodiments of the present invention, the raw material composition of the aluminum alloy includes: Si is 6.5-9%, Mn is 0.2-0.5%, Fe is 0.15-0.5%, V is 0-0.2%, and the balance is Al and inevitable impurities.

[0012] In one or more embodiments of the present invention, the raw material composition of the aluminum alloy includes: Si is 7-8%, Mn is 0.3-0.4%, Fe is 0.15-0.4%, V is 0-0.15%, and the balance is Al and inevitable impurities.

[0013] In one or more embodiments of the present invention, a method for preparing a cast aluminum alloy with high elongation comprises:

[0014] S1. Raw material preparation: prepare raw materials, preheat and dry them for standby use; the preferred raw materials are pure metals, master alloys, corresponding metal agents (manganese agents, iron agents, etc.) or recycled aluminum alloy waste, etc.;

[0015] S2. Alloy melting: adding the raw materials into a melting furnace in order, heating and melting them, and stirring them evenly to obtain an alloy melt;

[0016] S3, refining and impurity removal: applying protective gas to the alloy melt for degassing and refining, then adding refiners and modifiers, and finally removing surface slag;

[0017] S4, gravity casting: gravity casting the melt treated in step S3 to obtain an aluminum alloy ingot. Preferably, the intermediate alloy is selected from Al-20Si, Al-10Mn, Al-10Fe, and Al-5V. Preferably, the order and parameters of raw material addition are: first heat the pure Al ingot and Al-Si intermediate alloy to 720-780°C, and then add Al-Mn, Al-Fe, Al-V and other intermediate alloys after they are completely melted. Stir evenly after complete melting, stir for 5-10 minutes, and then let stand for 5-10 minutes. Preferably, the gravity casting temperature in S4 is 680-710°C, and the casting mold is one or more of a steel mold, a copper mold, a water-cooled copper mold, and a water-cooled steel mold.

[0018] In one or more embodiments of the present invention, the preheat drying in S1 is sufficient drying at 100-500°C.

[0019] In one or more embodiments of the present invention, the protective gas in S3 is selected from argon, helium, and nitrogen. Preferably, the degassing conditions are a temperature of 740 to 760° C. and a degassing time of 10 to 60 min.

[0020] In one or more embodiments of the present invention, the refiner in S3 is Al-5Ti-B or TCB. Preferably, the amount of the refiner added is 0.15-0.4 wt.%.

[0021] In one or more embodiments of the present invention, the modifier in S3 is Al10Sr master alloy. Preferably, the amount of the modifier added is 0.015-0.03 wt.%.

[0022] In one or more embodiments of the present invention, the alloy raw material melting equipment is a high-temperature box-type resistance furnace or a medium-frequency induction heating furnace, and the melt insulation device is a high-temperature box-type resistance furnace, and the insulation temperature is accurate to ±2°C.

[0023] In one or more embodiments of the present invention, the degassing equipment is a motor-type graphite rotor degasser with variable frequency speed regulation and a speed range of 0 to 1000 rpm.

[0024] In one or more embodiments of the present invention, at least in the S1 preparation stage (at least implemented simultaneously in the S1 stage or completed in advance before the S1 stage, etc.), all tools and equipment that are in direct contact with the melt are also preheated, and at least the surface in contact with the melt is coated with a coating. All surfaces of tools and equipment that are in direct contact with the melt need to be preheated and then evenly coated with a coating of about 1 to 3 mm in thickness, with a preheating temperature of 200 to 400°C. The coating includes sodium-free silicate coating, ceramic coating, boron nitride and silicon nitride coating, etc.

[0025] Compared with the prior art, the cast aluminum alloy with high elongation and the preparation method of the present invention have fewer types of alloy elements added, low content of auxiliary elements, and good price controllability; they have very excellent elongation and medium strength in the cast state; they do not require heat treatment and can meet the performance requirements of parts in the cast state, saving energy; they have a high tolerance for internal defects of the ingot, and large-size castings can achieve high toughness in all regions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 The microstructure diagrams of different regions of the alloy of Example 1 of the present invention are as follows: (a), (b): near-wall region; (c), (d): central region;

[0028] Figure 2 This is a microstructure diagram of the alloy of Example 2 of the present invention; DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0030] The present invention provides a casting aluminum alloy with high elongation which can be industrially applied in the cast state, wherein the main alloy system is AlSiMn(FeV), wherein

[0031] Si element: A medium content of silicon can ensure that the alloy has sufficient fluidity and form a eutectic structure (secondary α-Al+Si) in the alloy to strengthen the alloy;

[0032] Mn element: refines grains, prevents mold sticking, and regulates iron phase. It plays different roles depending on the Fe content in the alloy: under low iron (≤0.2wt.%) conditions, it mainly plays a role in improving sticking; under high iron content (≥0.2wt.%), it mainly plays a role in regulating the iron phase;

[0033] Fe element: Recycled aluminum scrap can be used directly without additional Fe removal and reduction process, and the Fe tolerance is higher;

[0034] V element: refines grain structure, regulates Fe phase, and controls the dispersion and precipitation of primary phase;

[0035] Sr element: Modifies Si to prevent deterioration of performance;

[0036] Including but not limited to the following examples, the description of sample properties is the average value of multiple random samples taken from the same casting.

[0037] Embodiment 1:

[0038] The present embodiment discloses a high elongation cast aluminum alloy and a preparation method, the components and weight percentages of the aluminum alloy are: Si: 9%, Fe: 0.45%, Mn: 0.3%, and the rest is Al. Before the smelting experiment begins, each smelting tool and degassing rotor are preheated to 250°C and evenly coated with 2mm boron nitride coating (such as using Pyrotech (Shenzhen) High Temperature Materials Co., Ltd.; specification model: BN Lubricoat Blue ZV). The preparation method of the cast aluminum alloy based on the above composition in this embodiment includes the following steps: S1. Batching: quantitatively weigh the raw materials according to the designed composition, and fully dry them in a drying furnace at 300°C. S2. Smelting: pure Al and Al-20Si (Refers to the Si content in the master alloy being 20wt%, the same below) Place it in a graphite clay crucible and melt it in a high-temperature box-type resistance furnace at 730℃. After it is melted, add Al-10Fe and Al-10Mn intermediate alloys to continue smelting. After it is completely melted, stir for 10 minutes to obtain a uniform melt. S3, refining: Use a graphite rotor degasser to pass argon into the aluminum alloy melt at 740℃ for refining. The argon gas flow rate is 0.1L / min, and the refining time is 15min. After standing for 5min, add 0.02% modifier Al10Sr intermediate alloy at 720℃, stir and stand, then add 0.3% refiner TCB, stir and stand, then skim off the slag and remove impurities. S4, casting: The refined aluminum alloy melt is cast through a water-cooled copper mold to obtain an aluminum alloy ingot.

[0039] The cast aluminum alloy has a fracture elongation of 24.9% in the cast state, a yield strength of 94 MPa, and a tensile strength of 191 MPa.

[0040] Embodiment 2:

[0041] The present embodiment discloses a high elongation cast aluminum alloy and a preparation method thereof. The components and weight percentages of the aluminum alloy are: Si: 9%, Fe: 0.35%, Mn: 0.2%, V: 0.3%, and the rest is Al. Before the smelting experiment begins, each smelting tool and degassing rotor are preheated to 200°C and evenly coated with 2mm boron nitride coating (such as using Pyrotech (Shenzhen) High Temperature Materials Co., Ltd.; specification model: BN Lubricoat Blue ZV). The preparation method of the cast aluminum alloy based on the above composition in this embodiment includes the following steps: S1, batching: weigh the raw materials quantitatively according to the designed composition, and fully dry them at 300°C in a drying furnace. S2, smelting: place pure Al and Al-20Si in a graphite clay crucible and melt them in a medium frequency induction furnace at 730°C. After the melting is completed, add Al-10Fe, Al-10Mn, Al-5V and other intermediate alloys to continue smelting, and stir for 10 minutes after it is completely melted to obtain a uniform melt. S3, refining: 740 ℃ using graphite rotor degasser to pass argon into the aluminum alloy melt for refining, argon gas flow rate 0.1L / min, refining time 20min, after standing for 5min, 720 ℃ add 0.02% modifier Al10Sr master alloy, stirring and standing, add 0.3% refiner Al-5Ti-B, stirring and standing, slag removal. S4, casting: the refined aluminum alloy melt is cast through a water-cooled copper mold to obtain an aluminum alloy ingot.

[0042] The cast aluminum alloy has a fracture elongation of 26.4% in the cast state, a yield strength of 92 MPa, and a tensile strength of 199 MPa.

[0043] Embodiment 3:

[0044] The present embodiment discloses a high elongation cast aluminum alloy and a preparation method thereof. The components and weight percentages of the aluminum alloy are: Si: 7.0%, Fe: 0.2%, Mn: 0.1%, V: 0.2%, and the rest is Al. Before the smelting experiment begins, the smelting tools and degassing rotors are preheated to 300°C and evenly coated with 2mm boron nitride coating (such as using Pyrotech (Shenzhen) High Temperature Materials Co., Ltd.; specification model: BN Lubricoat Blue ZV). The preparation method of the cast aluminum alloy based on the above composition in this embodiment includes the following steps: S1, batching: weigh the raw materials quantitatively according to the designed composition, and fully dry them at 100°C in a drying furnace. S2, smelting: place pure Al and Al-20Si in a graphite clay crucible and melt them in a medium frequency induction furnace at 730°C. After the melting is completed, add Al-10Fe, Al-10Mn, Al-5V and other intermediate alloys to continue smelting, and stir for 5 minutes after it is completely melted to obtain a uniform melt. S3, refining: 750 ℃ ​​using graphite rotor degasser to pass argon into the aluminum alloy melt for refining, argon gas flow rate 0.1L / min, refining time 15min, after standing for 5min, 720 ℃ add 0.015% modifier Al10Sr master alloy, stirring and standing, add 0.2% refiner TCB, stirring and standing, slag removal. S4, casting: the refined aluminum alloy melt is cast through a water-cooled steel mold to obtain an aluminum alloy ingot.

[0045] The cast aluminum alloy has a fracture elongation of 22.4% in the cast state, a yield strength of 98 MPa, and a tensile strength of 202 MPa.

[0046] Embodiment 4:

[0047] The present embodiment discloses a high elongation cast aluminum alloy and a preparation method thereof. The components and weight percentages of the aluminum alloy are: Si: 8.0%, Fe: 0.5%, Mn: 0.4%, V: 0.1%, and the rest is Al. Before the smelting experiment begins, each smelting tool and degassing rotor are preheated to 400°C and evenly coated with a sodium-free ceramic phase coating (Beijing Zhisheng Weihua Chemical Co., Ltd., model: ZS-1, name: high temperature resistant water-based environmentally friendly ceramic coating (sodium-free)). The preparation method of the cast aluminum alloy based on the above components in this embodiment includes the following steps: S1, batching: weigh the raw materials quantitatively according to the designed components, and fully dry them at 500°C in a drying furnace. S2, smelting: place pure Al and Al-20Si in a graphite clay crucible and melt them in a high temperature box-type resistance furnace at 760°C. After the melting is completed, add Al-10Fe, Al-10Mn, Al-5V and other intermediate alloys to continue smelting, and stir for 8 minutes after it is completely melted to obtain a uniform melt. S3, refining: 760 ℃ using graphite rotor degasser to pass argon into the aluminum alloy melt for refining, argon gas flow rate 0.1L / min, refining time 30min, after standing for 5min, 720 ℃ add 0.025% modifier Al10Sr master alloy, stir and stand, add 0.25% refiner TCB, stir and stand, and then remove slag and impurities. S4, casting: the refined aluminum alloy melt is cast through a water-cooled steel mold to obtain an aluminum alloy ingot.

[0048] The cast aluminum alloy has a fracture elongation of 19.5% in the cast state, a yield strength of 101 MPa, and a tensile strength of 188 MPa.

[0049] Embodiment 5:

[0050] The difference between this embodiment and embodiment 1 is that the components and weight percentages of the aluminum alloy are: Si: 10%, Fe: 0.6%, Mn: 0.6%, and the rest is Al.

[0051] The cast aluminum alloy has a fracture elongation of 18.1% in the cast state, a yield strength of 103 MPa, and a tensile strength of 184 MPa.

[0052] Embodiment 6:

[0053] The only difference between this embodiment and embodiment 1 is that the components and weight percentages of the aluminum alloy are: Si: 6%, Fe: 0.15%, Mn: 0.1%, and the rest is Al.

[0054] The cast aluminum alloy has a fracture elongation of 25.3% in the cast state, a yield strength of 87 MPa, and a tensile strength of 180 MPa.

[0055] Embodiment 7:

[0056] The only difference between this embodiment and embodiment 3 is that the components and weight percentages of the aluminum alloy are: Si: 7.0%, Fe: 0.2%, Mn: 0.1%, V: 0.15%, and the rest is Al.

[0057] The cast aluminum alloy has a fracture elongation of 23.6% in the cast state, a yield strength of 107 MPa, and a tensile strength of 195 MPa.

[0058] Embodiment 8:

[0059] The only difference between this embodiment and embodiment 4 is that the components and weight percentages of the aluminum alloy are: Si: 9.0%, Fe: 0.35%, Mn: 0.2%, V: 0.15%, and the rest is Al.

[0060] The cast aluminum alloy has a fracture elongation of 20.9% in the cast state, a yield strength of 103 MPa, and a tensile strength of 194 MPa.

[0061] Embodiment 9:

[0062] The only difference between this embodiment and embodiment 3 is that the components and weight percentages of the aluminum alloy are: Si: 7.0%, Fe: 0.4%, Mn: 0.25%, V: 0.2%, and the rest is Al.

[0063] The cast aluminum alloy has a fracture elongation of 20.2% in the cast state, a yield strength of 102 MPa, and a tensile strength of 196 MPa.

[0064] Embodiment 10:

[0065] The only difference between this embodiment and embodiment 4 is that the components and weight percentages of the aluminum alloy are: Si: 9.0%, Fe: 0.4%, Mn: 0.2%, V: 0.3%, and the rest is Al.

[0066] The cast aluminum alloy has a fracture elongation of 19.7%, a yield strength of 99 MPa, and a tensile strength of 191 MPa in the cast state.

[0067] Embodiment 11:

[0068] The difference between this embodiment and embodiment 3 is as follows: S3, refining: argon gas is introduced into the aluminum alloy melt at 750°C for refining, the argon gas introduction amount is 0.1L / min, the refining time is 15min, after standing for 5min, 0.02% of the modifier Al10Sr intermediate alloy is added at 720°C, after stirring and standing, 0.15% of the refiner TCB is added, and after stirring and standing, slag is removed.

[0069] The cast aluminum alloy has a fracture elongation of 22.9% in the cast state, a yield strength of 95 MPa, and a tensile strength of 203 MPa.

[0070] Embodiment 12:

[0071] The difference between this embodiment and embodiment 4 is as follows: S3, refining: argon gas is introduced into the aluminum alloy melt at 750°C for refining, the argon gas introduction amount is 0.1L / min, the refining time is 15min, after standing for 5min, 0.02% of the modifier Al10Sr master alloy is added at 720°C, after stirring and standing, 0.15% of the refiner TCB is added, and after stirring and standing, slag is removed.

[0072] The cast aluminum alloy has a fracture elongation of 20.1% in the cast state, a yield strength of 99 MPa, and a tensile strength of 195 MPa.

[0073] Embodiment 13:

[0074] The difference between this embodiment and embodiment 3 is as follows: S3, refining: argon gas is introduced into the aluminum alloy melt at 750°C for refining, the argon gas introduction amount is 0.1L / min, the refining time is 15min, after standing for 5min, 0.03% of the modifier Al10Sr intermediate alloy is added at 720°C, after stirring and standing, 0.4% of the refiner TCB is added, and after stirring and standing, slag is removed.

[0075] The cast aluminum alloy has a fracture elongation of 21.9% in the cast state, a yield strength of 97 MPa, and a tensile strength of 199 MPa.

[0076] Embodiment 14:

[0077] The difference between this embodiment and embodiment 4 is that: S3, refining: argon gas is introduced into the aluminum alloy melt at 750°C for refining, the argon gas introduction amount is 0.1L / min, the refining time is 15min, after standing for 5min, 0.03% of the modifier Al10Sr intermediate alloy is added at 720°C, after stirring and standing, 0.4% of the refiner TCB is added, and after stirring and standing, slag is removed.

[0078] The cast aluminum alloy has a fracture elongation of 20.5% in the cast state, a yield strength of 103 MPa, and a tensile strength of 186 MPa.

[0079] Comparative Example 1:

[0080] This comparative example discloses a high elongation cast aluminum alloy and a preparation method, the components and weight percentages of the aluminum alloy are: Si: 6.5%, Fe: 0.4%, Mn: 0.4%, V: 0.15%, Mg: 0.2%, Cu: 1.0%, and the rest is Al. The preparation method of the cast aluminum alloy based on the above components in this embodiment includes the following steps: S1, batching: weigh the raw materials quantitatively according to the designed components, and fully dry them in a drying furnace at 300°C. S2, smelting: add pure Al and Al-20Si into the smelting furnace and melt them at 730°C. After the melting is completed, add pure Cu, Al-10Fe, Al-10Mn, Al-5V and other intermediate alloys to continue smelting. After stirring for 5 minutes, the temperature is reduced to 720°C and pure Mg is added. It is pressed in using a bell jar. After it is completely melted, stir for 10 minutes to obtain a uniform melt. S3, refining: 740 ℃ into the aluminum alloy melt into argon refining, argon gas flow rate 0.1L / min, refining time 20min, after standing for 5min, 720 ℃ add 0.02% modifier, stirring and standing, add 0.03% refiner, stirring and standing, after slag removal. S4, casting: the refined aluminum alloy melt is cast through a copper mold to obtain an aluminum alloy ingot.

[0081] The cast aluminum alloy has a fracture elongation of 9.3% in the cast state, a yield strength of 128 MPa, and a tensile strength of 253 MPa.

[0082] Main alloying element contents (wt.%) of the embodiments and comparative examples:

[0083]

[0084]

[0085] Performance statistics of embodiments and comparative examples:

[0086] Elongation after break (%) Yield strength (MPa) Tensile strength(MPa) Example 1 24.9 94 191 Example 2 26.4 92 199 Example 3 22.4 98 202 Example 4 19.5 101 188 Example 5 18.1 103 184 Example 6 25.3 87 180 Example 7 23.6 107 195 Example 8 20.9 103 194 Example 9 20.2 102 196 Example 10 19.7 99 191 Embodiment 11 22.9 95 203 Example 12 20.1 99 195 Embodiment 13 21.9 97 199 Embodiment 14 20.5 103 186 Comparative Example 1 9.3 128 253

[0087] Including but not limited to the above embodiments: the selection of preheating and drying in S1 and / or the selection of protective gas in S3 and / or the selection of degassing conditions in S3, etc., do not affect the implementation of the method of the present invention and the realization of the technical effects, so they are not listed one by one. Including but not limited to the above schemes, they can all be equally replaced without significantly affecting the effects of the embodiments.

[0088] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0089] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A cast aluminum alloy with high elongation, the raw material composition of which includes: Si is 6-10wt.%, Mn is 0.1-0.6wt.%, Fe is 0.15-0.6wt.%, and the balance is Al and inevitable impurities.

2. The cast aluminum alloy with high elongation according to claim 1, characterized in that It also includes V being 0 to 0.3%.

3. The cast aluminum alloy with high elongation according to claim 2, characterized in that The raw material composition of the aluminum alloy includes: Si is 6.5-9%, Mn is 0.2-0.5%, Fe is 0.15-0.5%, V is 0-0.2%, and the balance is Al and inevitable impurities.

4. The cast aluminum alloy with high elongation according to claim 3, characterized in that The raw material composition of the aluminum alloy includes: Si is 7-8%, Mn is 0.3-0.4%, Fe is 0.15-0.4%, V is 0-0.15%, and the balance is Al and inevitable impurities.

5. The method for preparing a cast aluminum alloy with high elongation according to any one of claims 1 to 4, comprising: S1. Raw material preparation: prepare raw materials, preheat and dry them for later use; S2. Alloy melting: adding the raw materials into a melting furnace in order, heating and melting them, and stirring them evenly to obtain an alloy melt; S3, refining and impurity removal: applying protective gas to the alloy melt for degassing and refining, then adding a refiner and a modifier, and finally removing surface scum; S4, gravity casting: gravity casting the melt processed in step S3 to obtain the aluminum alloy ingot.

6. The method for preparing a cast aluminum alloy with high elongation according to claim 5, characterized in that: The preheat drying in S1 is to fully dry at 100-500°C.

7. The method for preparing a cast aluminum alloy with high elongation according to claim 5, characterized in that: The protective gas in S3 is selected from argon, helium and nitrogen.

8. The method for preparing a cast aluminum alloy with high elongation according to claim 5, characterized in that: The refiner in S3 is Al-5Ti-B or TCB.

9. The method for preparing a cast aluminum alloy with high elongation according to claim 5, characterized in that: The modifier in S3 is Al10Sr master alloy.

10. The method for preparing a cast aluminum alloy with high elongation according to claim 5, characterized in that: At least in the S1 preparation stage, all tools and equipment that are in direct contact with the melt are also preheated, and at least the surfaces that are in contact with the melt are coated.

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