Aluminum-silicon alloy and die-casting process thereof

Abstract

The invention relates to an aluminum-silicon alloy and a die-casting process thereof. The die-casting process of the aluminum-silicon alloy comprises the following steps: melting alloy raw materials, degassing and refining, carrying out semi-solid pulping, adding a refiner in the semi-solid pulping process, stirring, reducing the temperature of a semi-solid alloy melt, and continuously stirring, so as to realize primary refinement and modification of primary crystal grains and broken dendrites formed in the semi-solid slurry; a semi-solid alloy melt is obtained; and chilling, solidifying and forming the semi-solid alloy melt, and quenching to obtain the aluminum-silicon alloy casting. The invention further provides the aluminum-silicon alloy prepared through the die-casting technology. The problem that an existing refiner cannot meet the good refining effect and the good modification effect at the same time is solved, and the problems that an existing aluminum-silicon alloy die casting is thick in structure and poor in tensile property are further solved.

Description

Technical Field

[0001] The invention relates to the technical field of alloy processing, and in particular to an aluminum-silicon alloy and a die-casting process thereof. Background Art

[0002] Semi-solid rheocasting, as a green and efficient forming process, can produce high-performance castings. Compared with traditional die-casting methods, it has significant advantages: it can refine grains, optimize the morphology and distribution of the second phase, significantly reduce casting defects inside and on the surface of castings, and improve the density, mechanical and thermal conductivity of castings. And because of the low porosity, rheocasting parts can directly accept high-temperature heat treatment strengthening and welding.

[0003] However, in the preparation process of aluminum-silicon alloy, the refinement of primary aluminum, the modification of eutectic silicon and the refinement of grains are crucial to improving the casting formability and mechanical properties of the alloy. Although the semi-solid die-casting process can effectively break up dendrites, its refinement effect is still insufficient for the relatively coarse block and needle-shaped silicon phases, resulting in the primary aluminum in the semi-solid aluminum-silicon alloy structure to maintain a coarse dendrite form, the primary silicon exists in block form, and the eutectic silicon phase is lamellar or lath-shaped. These coarse primary aluminum dendrites and lamellar eutectic silicon seriously split the matrix structure, greatly weakening the mechanical properties of the alloy, especially the plasticity.

[0004] To address the above problems, researchers have tried to refine silicon and primary grains by adding refiners such as Al-Ti-B and Al-Nb-B. 2 、NbAl 3 , NbB 2 Due to their large density and relative atomic mass, particles such as Al-Sr and Al-B are prone to agglomeration and sedimentation in the aluminum melt, resulting in poor anti-degradation performance of the refiner. After being added to the melt, it needs to be immediately stirred and cast, which limits its wide range of industrial applications. In terms of commercial hypoeutectic aluminum-silicon alloy modifiers, Na salt modifiers are gradually being replaced by more environmentally friendly and better-modifying Al-Sr intermediate alloy modifiers. However, when the Al-Sr modifier is used to modify the cast aluminum-silicon alloy after Al-B alloy refinement, its modification effect is not as good as adding Al-Sr alloy alone, and the grain refinement effect is also weakened. In addition, if Al-Ti-B, Al-Nb-B, etc. are added above 800°C and kept warm for a long time, TiB 2 、TiAl 3、 Nb 3 The precipitation of compounds such as TiB 2 、TiAl 3、 Nb 3It is also easy to produce aggregation defects, which will gather into lumps in the melt, further reducing the refinement effect. At the same time, the traditional modifier aluminum strontium is prone to pinhole defects on the casting surface due to its large tendency to absorb hydrogen. If the alloy contains elements such as Zr, Cr, and Mn, it is also easy to cause "poisoning" and refinement decline. Therefore, it is urgent to find a preparation process for uniform refinement and modification of aluminum silicon alloy. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide an aluminum-silicon alloy and a die-casting process thereof to solve the problem that the existing refiners cannot simultaneously meet the requirements of good refinement effect and good modification effect, and also to solve the problem that the existing aluminum-silicon alloy die-castings have coarse structure and poor tensile properties.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A die-casting process for aluminum-silicon alloy comprises the following steps: S1, melting the alloy raw materials to obtain an alloy melt; S2, degassing and refining the alloy melt, performing semi-solid slurrying, adding a refiner during the semi-solid slurrying process, stirring, lowering the temperature of the semi-solid alloy melt and continuously stirring, so as to achieve a primary refinement and modification of the primary grains and broken dendrites formed in the semi-solid slurry, and obtain a semi-solid alloy melt; S3, the semi-solid alloy melt is solidified by rapid cooling and casting, and quenched to obtain an aluminum-silicon alloy casting.

[0007] According to the above technical means, the required alloy melt is obtained by melting the corresponding alloy raw materials, and the alloy melt is poured into a pulping device for semi-solid pulping, and a refiner is added during the semi-solid pulping process, and the mixture is first stirred and then cooled, and stirring is continued during the cooling process to achieve a primary refinement and metamorphism of the primary grains and broken dendrites formed by the semi-solid slurry, and the semi-solid alloy containing the primary solid phase that has undergone the primary refinement and metamorphism is introduced into a die casting cylinder for pressure casting, and the semi-solid alloy melt that has undergone the primary refinement and metamorphism is solidified under the dual effects of pressure and mold chilling, and the primary fine primary nucleation grains and unsolidified melt are secondary refined under the action of the refiner, so as to achieve a doubly refined aluminum alloy casting with uniform and fine structure, excellent strength and plasticity, and solves the problem that the existing refiner cannot simultaneously meet the requirements of good refinement effect and good metamorphism effect, and also solves the problem that the existing aluminum-silicon alloy castings have coarse grains and poor tensile properties during the production process.

[0008] The refiner consists of aluminum (Al), titanium (Ti), carbon (C), boron (B) and strontium (Sr), and the refiner also serves as a modifier in the preparation of aluminum-silicon alloy.

[0009] By using aluminum (Al), titanium (Ti), carbon (C), boron (B) and strontium (Sr) to form a refiner, the refiner can also be used as a modifier in the die-casting process of aluminum-silicon alloys. The primary grains and broken dendrites formed in the die-casting process can be refined and modified once, which can effectively reduce the TiB 2 、TiAl 3 , TiC and other nucleation particles, thereby improving the multiple modification and refinement effects of primary silicon, eutectic silicon and grains. This effectively solves the problem that existing refiners cannot simultaneously meet the requirements of good refinement and modification effects.

[0010] Preferably, the mass ratio of aluminum (Al), titanium (Ti), carbon (C), boron (B) and strontium (Sr) is 1:2:0.2:0.5:0.2.

[0011] Preferably, the refiner is composed of Al-10Sr master alloy and Al-Ti-CB composite material. Al-10Sr master alloy means that the percentage of aluminum is 90% and the percentage of titanium is 10%.

[0012] Al-Ti-CB composite material can also be replaced by Al-2Ti-0.2C-0.5B composite material. Al-Ti-CB means that the percentage of aluminum is 25%, the percentage of titanium is 25%, the percentage of carbon is 25%, and the percentage of boron is 25%. Al-2Ti-0.2C-0.5B means that the percentage of aluminum is 97.3%, the percentage of titanium is 2%, the percentage of carbon is 0.2%, and the percentage of boron is 0.5%.

[0013] Preferably, in said S1, the alloy raw material is selected from aluminum silicon alloy.

[0014] Preferably, in the S1, the mass percentage of Si element in the aluminum-silicon alloy is between 5% and 12%, and the content of other trace elements, such as Cr, Mn, etc., is less than 2%.

[0015] Preferably, in S1, the melting temperature is 750-800°C.

[0016] By melting the alloy raw materials at a temperature of 750-800°C, the volatilization is reduced on the basis of faster melting of the alloy, ensuring the accuracy of the alloy composition. At the same time, adding the refiner and stirring at a temperature of 750-800°C effectively ensures the dissolution of the master alloy. The stirring treatment further disperses the modification refiner in the alloy melt, improving its modification and refinement effect.

[0017] Preferably, in S2, the degassing and refining time is 10 to 20 minutes.

[0018] Preferably, in S2, the gas for degassing and refining is selected from one or both of anhydrous nitrogen and anhydrous argon.

[0019] Preferably, the gas used for degassing and refining is selected from anhydrous argon, which has high inertness and density.

[0020] By degassing and refining the alloy melt, hydrogen and inclusions in the alloy melt can be effectively removed to obtain a high-quality alloy melt.

[0021] Preferably, in S2, the amount of the refiner added is 0.5% to 1.5% of the total weight of the semi-solid aluminum-silicon alloy.

[0022] Preferably, in S2, the amount of the refiner added is 1% of the total weight of the semi-solid aluminum-silicon alloy.

[0023] Preferably, in S2, the stirring is selected from at least one of mechanical stirring, ultrasonic vibration, electromagnetic stirring, inclined plate casting and air-cooled stirring.

[0024] Preferably, in S2, the solid phase ratio of the semi-solid slurry is 20-60%.

[0025] Preferably, in S2, the temperature of the semi-solid alloy melt is reduced to 560-600°C.

[0026] Preferably, in S3, the semi-solid alloy melt is sent to a pressure chamber at a temperature of 100-120°C, and then pressed into a mold at a temperature of 150-250°C for chilling and solidification.

[0027] Preferably, in S3, the quenching temperature is 20-50°C.

[0028] Preferably, S3 specifically includes: sending the semi-solid alloy melt to a pressure chamber with a temperature of 100-120°C, and then pressing it into a mold with a temperature of 150-250°C for chilling and solidification, taking out the casting, quenching it, and obtaining an aluminum-silicon alloy casting, and obtaining a die-casting with sufficient refinement of primary aluminum and effective metamorphosis of eutectic silicon.

[0029] Preferably, the speed at which the semi-solid alloy melt is pressed into the mold is 0.1-1.5 m / s, the injection pressure is 100-150 MPa, and the holding time is 5-10 s.

[0030] Preferably, the heating method of the mold is selected from at least one of electromagnetic induction heating, resistance coil heating, steam heating and dielectric heating.

[0031] Preferably, the semi-solid alloy melt is cooled by water cooling, oil cooling, gas cooling or salt bath cooling.

[0032] Preferably, after S3, the method further includes: S4, performing solution treatment, water quenching, aging treatment and air cooling on the aluminum-silicon alloy die casting; The temperature of the solution treatment is 525-545°C, and the time of the solution treatment is 2-3 hours; The temperature of the aging treatment is 155-175° C., and the time of the aging treatment is 0-10 hours.

[0033] By performing short-time solid solution and aging treatment on aluminum-silicon alloy die castings, the mechanical properties of the alloy are further improved, and the strength and toughness of the alloy are significantly improved.

[0034] The present invention also provides an aluminum-silicon alloy, which is prepared by the die-casting process of the present invention.

[0035] Beneficial effects of the present invention: The aluminum-silicon alloy die-casting process of the present invention first obtains a high-quality alloy melt by accurately controlling the melting process of the alloy raw material. Subsequently, the melt is introduced into an advanced pulping device for semi-solid pulping treatment to ensure that the microstructure of the alloy reaches an ideal state. In the pulping process, a modified refiner is cleverly introduced, and through disturbance and cooling technology, the refiner fully acts on the primary grains formed in the semi-solid slurry to achieve primary refinement and modification. This process not only refines the grains, but also improves the organizational structure of the alloy, laying a solid foundation for subsequent casting. Then, the semi-solid alloy that has undergone primary refinement and modification is introduced into a die-casting cylinder for pressure casting. Under the combined action of pressure and mold chilling, the alloy melt solidifies rapidly to form a dense casting. In this process, the primary fine primary nucleation grains and the unsolidified melt undergo a secondary refinement process under the continuous action of the refiner, further improving the microstructure uniformity and performance of the casting. The die-casting process of the present invention successfully produces aluminum alloy castings with uniform and fine structure, excellent strength and plasticity, which not only effectively solves the key problems of coarse grains and poor tensile properties in the production process of existing aluminum-silicon alloy castings, but also shows broad promotion and application prospects in the field of alloy processing technology.

[0036] The aluminum-silicon alloy die-casting process of the present invention realizes the dual functions of refiner and modifier by carefully blending elements such as aluminum (Al), titanium (Ti), carbon (C), boron (B) and strontium (Sr). The refiner is applied to the aluminum-silicon alloy die-casting process, which can significantly optimize the refinement and modification process of primary grains during the die-casting process. The refiner can not only effectively slow down the TiB 2 、TiAl 3 It can increase the sedimentation rate of key nucleation particles such as TiC, and can also significantly improve the multiple metamorphic refinement effects of primary silicon, eutectic silicon and the overall grains, opening up a new way to improve the performance of aluminum-silicon alloys, and has promotion and application value in the field of alloy processing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a SEM image of the refined squeeze-cast Al-9Si alloy obtained in Example 1; Figure 2 is a SEM image of the refined squeeze-cast Al-12Si alloy obtained in Example 2; Figure 3 is a SEM image of the refined squeeze-cast Al-6Si alloy obtained in Example 3; Figure 4 This is the SEM image of the squeeze cast Al-9Si alloy before refinement prepared in Control Example 1. DETAILED DESCRIPTION

[0038] The following will describe the embodiments of the present invention with reference to the preferred embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0039] The present invention is intended to disclose an aluminum-silicon alloy and a die-casting process thereof, so as to solve the problem that the existing refiner cannot simultaneously meet the requirements of good refinement effect and good modification effect, and can also solve the problem that the existing aluminum-silicon alloy die-castings have coarse structure and poor tensile properties.

[0040] Among them, a die-casting process of aluminum-silicon alloy includes the following steps: S1, melting the alloy raw materials to obtain an alloy melt; S2, degassing and refining the alloy melt, performing semi-solid slurrying, adding a refiner during the semi-solid slurrying process, stirring, lowering the temperature of the semi-solid alloy melt and continuously stirring, so as to achieve a primary refinement and modification of the primary grains and broken dendrites formed in the semi-solid slurry, and obtain a semi-solid alloy melt; S3, solidifying the semi-solid alloy melt by rapid cooling, and quenching to obtain an aluminum-silicon alloy casting.

[0041] The desired alloy melt is obtained by melting corresponding alloy raw materials, and the alloy melt is poured into a pulping device for semi-solid pulping. A metamorphic refiner is added into the disturbed semi-solid pulping process and the temperature is lowered, and the primary grains formed by the semi-solid slurry are subjected to a first refinement and metamorphism. The semi-solid alloy containing the primary solid phase after the first refinement and metamorphism is introduced into a die casting cylinder for pressure casting. The semi-solid alloy melt after the first refinement and metamorphism is solidified under the dual effects of pressure and mold chilling, and the primary fine primary nucleation grains and unsolidified melt are secondarily refined under the action of the refiner, so as to realize a double-refined aluminum alloy casting with uniform and fine structure, excellent strength and plasticity, and solves the problems of coarse grains and poor tensile properties of existing aluminum-silicon alloy castings in the production process.

[0042] In some embodiments, the refiner is composed of aluminum (Al), titanium (Ti), carbon (C), boron (B) and strontium (Sr); the refiner also acts as a modifier in the preparation of aluminum silicon alloy.

[0043] In some embodiments, the mass ratio of aluminum (Al), titanium (Ti), carbon (C), boron (B), and strontium (Sr) is 1:2:0.2:0.5:0.2.

[0044] In some embodiments, the refiner consists of Al-10Sr master alloy and Al-Ti-CB composite material.

[0045] In some embodiments, during the extrusion casting process, the shrinkage compensation can be optimized and forced shrinkage compensation can be achieved by cooling the corresponding positions on the mold and heating the gate, thereby further improving the density of the casting.

[0046] In some embodiments, in S1, the alloy raw material is selected from aluminum silicon alloy, wherein the Si element content is between 5% and 12%, and the content of other trace elements, such as Cr, Mn, etc., is less than 2%.

[0047] In some embodiments, in S1, in order to reduce volatilization while melting the alloy faster and ensure the accuracy of the alloy composition, the melting temperature is set to 750-800°C.

[0048] At the same time, adding refiners and stirring at a temperature of 750-800 °C effectively ensures the dissolution of the master alloy. The stirring treatment further disperses the refiners in the alloy melt, improving its refinement effect.

[0049] In some embodiments, in S2, in order to remove hydrogen and inclusions in the alloy melt and obtain a high-quality alloy melt, the degassing refining time is set to 10 to 20 minutes.

[0050] In some embodiments, in S2, the gas used for degassing and refining is selected from one or both of anhydrous nitrogen and anhydrous argon.

[0051] Exemplarily, the gas for degassing and refining is selected from anhydrous argon. Anhydrous argon has high inertness and high density.

[0052] In some embodiments, in S2, the refiner is composed of an aluminum-strontium (Al-Sr) master alloy and an Al-Ti-CB composite material.

[0053] In some embodiments, in S2, the amount of the refiner added is 0.5% to 1.5% of the total weight of the semi-solid aluminum-silicon alloy.

[0054] Exemplarily, in S2, the amount of the refiner added is 1% of the total amount of the semi-solid aluminum-silicon alloy.

[0055] In some embodiments, in S2, stirring is selected from at least one of mechanical stirring, ultrasonic vibration, electromagnetic stirring, inclined plate casting and air-cooled stirring.

[0056] In some embodiments, in S2, the solid phase ratio of the semi-solid slurry is 20-60%.

[0057] In some embodiments, in S2, the temperature of the semi-solid alloy melt is reduced to 560-600°C.

[0058] In some embodiments, in S3, the semi-solid alloy melt is sent to a pressure chamber with a temperature of 100-120°C, and then pressed into a mold with a temperature of 150-250°C for chilling and solidification.

[0059] In some embodiments, in S3, the quenching water temperature is 20-50°C.

[0060] Exemplarily, S3 specifically includes: sending the semi-solid alloy melt to a pressure chamber with a temperature of 100-120°C, and then pressing it into a mold with a temperature of 150-250°C for chilling and solidification, taking out the casting, quenching it, and obtaining an aluminum-silicon alloy casting, and obtaining a die-casting with sufficient refinement of primary aluminum and effective modification of eutectic silicon.

[0061] Exemplarily, the speed at which the semi-solid alloy melt is pressed into the mold is 0.1-1.5 m / s, the injection pressure is 100-150 MPa, and the holding time is 5-10 s.

[0062] Exemplarily, the heating method of the mold is selected from at least one of electromagnetic induction heating, resistance coil heating, steam heating and dielectric heating.

[0063] In some embodiments, the semi-solid alloy melt is cooled by water cooling, oil cooling, gas cooling or salt bath cooling.

[0064] In some embodiments, in order to further improve the mechanical properties of the alloy and significantly increase the strength and toughness of the alloy, after S3, the process further includes: S4, performing solution treatment, water quenching, aging treatment and air cooling on the aluminum-silicon alloy die casting; The temperature of the solution treatment is 525-545°C, and the time of the solution treatment is 2-3 hours; The temperature of the aging treatment is 155-175° C., and the time of the aging treatment is 0-10 hours.

[0065] By performing short-time solid solution and aging treatment on aluminum-silicon alloy die castings, the mechanical properties of the alloy are further improved, and the strength and toughness of the alloy are significantly improved.

[0066] In some embodiments, an aluminum-silicon alloy is also provided, which is prepared using any of the above-mentioned die-casting processes.

[0067] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the die-casting process of the aluminum-silicon alloy of the present invention will be further described in detail below in combination with specific embodiments and drawings. Obviously, the specific embodiments described are only part of the embodiments of the present application, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation to the present application and its applications. Based on the specific embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present application.

[0068] If no specific techniques or conditions are specified in the specific embodiments, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0069] A die-casting process for aluminum-silicon alloy comprises the following steps: S1. Melting Al-9Si alloy raw material at a temperature of 800±15° C. to obtain an aluminum-silicon alloy melt; S2, the aluminum-silicon alloy melt in S1 is degassed and refined for 15 minutes, and semi-solid slurry is performed, and Al-10Sr master alloy and Al-2Ti-0.2C-0.5B refiner are added in the semi-solid slurry process, and Al-2Ti-0.2C-0.5B-0.2Sr refiner is obtained by proportioning, and a low-frequency spiral electromagnetic stirring device is started, with a rated current of 400 A and a frequency of 2-10 Hz, so that the melt can move up and down in a spiral in the crucible, and the temperature of the melt is reduced to 600 °C and stirred continuously, so as to drive the refiner to be evenly distributed in the melt, so as to achieve a refinement and modification of the primary grains and broken dendrites formed in the semi-solid slurry, and obtain a semi-solid alloy melt; S3, scoop out the semi-solid alloy melt, send it to a pressure chamber at a temperature of 120°C, and then press it into a mold at a temperature of 200°C for chilling and solidification, take out the casting, quench it, and obtain an aluminum-silicon alloy casting with primary aluminum fully refined twice and eutectic silicon effectively modified; The speed of the melt being pressed into the mold was 0.5 m / s, the injection pressure was 120 MPa, the holding time was 10 s, and the quenching temperature was 25 °C. S4. The aluminum-silicon alloy die casting in S3 is solution treated at a temperature of 535°C for 2.5 h, water quenched, and then aged at a temperature of 175°C for 3.5 h, and air-cooled to obtain a refined and modified Al-9Si alloy extrusion casting.

[0070] A die-casting process for aluminum-silicon alloy comprises the following steps: S1. Melting Al-12Si-1Cu-1Mg alloy raw material at a temperature of 780±15° C. to obtain an aluminum-silicon alloy melt; S2, the aluminum-silicon alloy melt in S1 is degassed and refined for 15 minutes, and semi-solid slurry is performed. Al-10Sr master alloy and Al-3Ti-0.3C-0.3B refiner are added in the semi-solid slurry process, and Al-3Ti-0.3C-0.3B-0.2Sr refiner is obtained after proportioning, and the melt is melted at 760°C, and a low-frequency spiral electromagnetic stirring device is started, with a rated current of 400 A and a frequency of 2-10 Hz, so that the melt can spiral up and down in the crucible, and the melt temperature is reduced to 600°C between the solid-liquid two-phase region and continuously stirred, so as to drive the refiner to be evenly distributed in the melt, so as to achieve a refinement and modification of the primary grains and broken dendrites formed in the semi-solid slurry, and obtain a semi-solid alloy melt; S3, scoop out the semi-solid alloy melt, send it to a pressure chamber at a temperature of 120°C, and then press it into a mold at a temperature of 150°C for chilling and solidification, take out the casting, quench it, and obtain an aluminum-silicon alloy casting with fully refined primary aluminum and effectively modified eutectic silicon; The speed of the melt being pressed into the mold was 0.5 m / s, the injection pressure was 120 MPa, the holding time was 10 s, and the quenching temperature was 25 °C. S4. The semi-solid aluminum-silicon alloy die casting in S3 is solution treated at a temperature of 535°C for 2.5 hours, water quenched, and then aged at a temperature of 175°C for 3.5 hours, and air-cooled to obtain a refined and modified Al-12Si-1Cu-1Mg alloy extrusion casting.

[0071] A die-casting process for aluminum-silicon alloy comprises the following steps: S1. Melting Al-6Si alloy raw material at a temperature of 780±15° C. to obtain an aluminum-silicon alloy melt; S2, the aluminum-silicon alloy melt in S1 is degassed and refined for 15 minutes, and semi-solid slurry is made, and Al-10Sr master alloy and Al-2Ti-0.2C-0.3B refiner are added in the semi-solid slurry process, and Al-2Ti-0.2C-0.3B-0.2Sr refiner is obtained by proportioning, and a low-frequency spiral electromagnetic stirring device is started, with a rated current of 400 A and a frequency of 2-10 Hz, so that the melt can move up and down in the crucible in a spiral, and the temperature is reduced to 600°C between the solid-liquid two-phase region and stirred continuously, so as to drive the refiner to be evenly distributed in the melt, so as to achieve a refinement and modification of the primary grains and broken dendrites formed in the semi-solid slurry, and obtain a semi-solid alloy melt; S3, scoop out the semi-solid alloy melt, send it to a pressure chamber at a temperature of 120°C, and then press it into a mold at a temperature of 150°C for chilling and solidification, take out the casting, quench it, and obtain an aluminum-silicon alloy casting with fully refined primary aluminum and effectively modified eutectic silicon; The speed of the melt being pressed into the mold was 0.5 m / s, the injection pressure was 120 MPa, the holding time was 10 s, and the quenching temperature was 25 °C. S4. The aluminum-silicon alloy die casting in S3 is solution treated at a temperature of 535°C for 2.5 h, water quenched, and then aged at a temperature of 175°C for 3.5 h, and air-cooled to obtain a refined and modified Al-6Si alloy extrusion casting.

[0072] Comparative Example 1 A die-casting process for aluminum-silicon alloy comprises the following steps: S1. Melting Al-9Si alloy raw material at a temperature of 780±15° C. to obtain an aluminum-silicon alloy melt; S2, degas and refine the aluminum-silicon alloy melt in S1 for 15 minutes, then stand at 730°C for 10 minutes and skim off the slag; S3, and start the low-frequency spiral electromagnetic stirring device, rated current: 400 A, frequency: 2~10 Hz, to achieve spiral up and down movement of the melt in the crucible, reduce the temperature to 600°C between the solid-liquid two-phase region, and obtain a semi-solid alloy melt; S4, sending the semi-solid melt to a pressure chamber at a temperature of 120°C, and then pressing it into a mold at a temperature of 150°C for chilling and solidification, taking out the casting, quenching it, and obtaining an Al-9Si alloy casting; The speed of the melt being pressed into the mold was 0.5 m / s, the injection pressure was 120 MPa, the holding time was 10 s, and the quenching temperature was 25 °C. S5. The die casting in S4 is solution treated at a temperature of 535°C for 2.5 h, water quenched, and then aged at a temperature of 175°C for 3.5 h, and air-cooled to obtain an Al-9Si alloy extrusion casting.

[0073] Detection and analysis 1) SEM analysis The Al-Si alloys prepared by extrusion casting in Example 1, Example 2, Example 3 and Comparative Example 1 were subjected to SEM analysis. The results are as follows: Figure 1 , Figure 2 , Figure 3 and Figure 4 shown.

[0074] from Figure 1 , Figure 2 , Figure 3 and Figure 4 Comparative analysis shows that the Si phase in the refined and heat-treated Al-Si alloys all presents a nearly spherical morphology, replacing the blocky and needle-shaped Si phases with coarse and sharp morphology in the unrefined Al-Si alloys. The average length of the Si phase is also reduced from 10~20 μm to 2~5 μm, which has an excellent second phase strengthening effect. At the same time, the addition of Al-Ti-CB-Sr refiner reduces the grain size of the three alloys in the embodiment to between 90~100 μm, which has excellent grain refinement and fine grain strengthening effects.

[0075] 2) Tensile strength, yield strength and elongation test The specific operation steps are as follows: The tensile test is carried out at room temperature using an MTS810 electronic universal testing machine according to GB / T228-2010 standard, and the tensile rate is 2 mm / min. The error of each tensile data is based on the test of at least 3 samples. The mechanical property test results of the aluminum-silicon alloy prepared in Example 1, Example 2, Example 3 and Comparative Example 1 are shown in Table 1.

[0076] Table 1 Mechanical properties of squeeze casting aluminum-silicon alloy Yield strength (MPa) Tensile strength (MPa) Elongation (%) Example 1 345±6.7 421.2±8.9 6.7±0.8 Example 2 353.6±5.8 426.8±7.6 5.9±0.6 Example 3 338.5±9.3 401.1±8.8 7.1±0.6 Comparative Example 1 334.5±8.3 371.3±6.9 3.6±0.3 From the comparative analysis in Table 1, it can be seen that the strength and elongation of the extrusion casting aluminum-silicon alloy after refinement treatment and solid solution aging treatment are greatly improved, and it has excellent strong-toughness coupling performance.

[0077] In summary, the aluminum-silicon alloy extrusion casting process of the present invention first obtains a high-quality alloy melt by accurately controlling the melting process of the alloy raw material. Subsequently, the melt is introduced into an advanced pulping device for semi-solid pulping treatment to ensure that the microstructure of the alloy reaches an ideal state. In the pulping process, a modified refiner is cleverly introduced, and through disturbance and cooling technology, the refiner is fully acted on the primary grains formed in the semi-solid slurry to achieve primary refinement and metamorphism. Under the action of spiral stirring, the alloy is always in a flowing state inside the semi-solid slurry, evenly distributed inside the melt, and the particles are dispersed and not easy to precipitate. Each crystal face of the particle can fully contact with the aluminum liquid, thereby ensuring a high primary crystal nucleation rate. This process not only refines the grains, but also improves the organizational structure of the alloy, laying a solid foundation for subsequent extrusion casting. Next, the semi-solid alloy that has undergone primary refinement and metamorphism is introduced into a die casting cylinder for pressure casting. Under the combined action of pressure and mold chilling, the alloy melt solidifies rapidly to form a dense casting. In this process, the primary fine nucleation grains and the unsolidified melt undergo a secondary refinement process under the continuous action of the refiner, further improving the microstructure uniformity and performance of the casting. The die-casting process of the present invention successfully produces aluminum alloy castings with uniform and fine structure, excellent strength and plasticity. This not only effectively solves the key problems of coarse grains and poor tensile properties in the existing aluminum-silicon alloy casting production process, but also shows a broad prospect for promotion and application in the field of alloy processing technology.

[0078] The aluminum-silicon alloy extrusion casting process of the present invention realizes the dual functions of a refiner and a modifier by carefully blending elements such as aluminum (Al), titanium (Ti), carbon (C), boron (B) and strontium (Sr). The refiner is applied to the extrusion casting process of aluminum-silicon alloy, which can significantly optimize the refinement and modification process of primary grains during the extrusion casting process. The refiner can not only effectively slow down the sedimentation rate of key nucleation particles such as TiB2, TiAl3, and TiC, but also significantly improve the multiple modification and refinement effects of primary silicon, eutectic silicon and overall grains, opening up a new way to improve the performance of aluminum-silicon alloys, and has promotion and application value in the field of alloy processing technology.

[0079] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent substitution or change made by a person skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A die-casting process for aluminum-silicon alloy, characterized in that: The following steps are involved: S1, melting the alloy raw materials to obtain an alloy melt; S2, degassing and refining the alloy melt, performing semi-solid slurrying, adding a refiner during the semi-solid slurrying process, stirring, lowering the temperature of the semi-solid alloy melt and continuously stirring, so as to achieve a primary refinement and modification of the primary grains and broken dendrites formed in the semi-solid slurry, and obtain a semi-solid alloy melt; S3, the semi-solid alloy melt is solidified by rapid cooling and casting, and quenched to obtain an aluminum-silicon alloy casting.

2. The die casting process according to claim 1, characterized in that: The refiner consists of aluminum (Al), titanium (Ti), carbon (C), boron (B) and strontium (Sr), and the refiner also serves as a modifier in the preparation of aluminum-silicon alloy.

3. The die casting process according to claim 2, characterized in that: The mass ratio of aluminum (Al), titanium (Ti), carbon (C), boron (B) and strontium (Sr) is 1:2:0.2:0.5:0.

2.

4. The die casting process according to claim 2, characterized in that: The refiner is composed of aluminum-strontium master alloy and Al-Ti-CB composite material; The aluminum-strontium master alloy is selected from Al-10Sr.

5. The die casting process according to claim 1, characterized in that: In S1, the alloy raw material is selected from aluminum-silicon alloy: the Si content in the aluminum-silicon alloy is between 5% and 12%, and the content of other trace elements is less than 2%; And / or, in S1, the melting temperature is 750-850°C.

6. The die casting process according to claim 1, characterized in that: In S2, the degassing and refining time is 10 to 20 minutes; And / or, in S2, the gas for degassing and refining is selected from one or both of anhydrous nitrogen and anhydrous argon.

7. The die casting process according to claim 4, characterized in that: The Al-Ti-CB composite material is selected from Al-2Ti-0.2C-0.5B composite material; And / or, in said S2, the amount of the refiner added is 0.5% to 1.5% of the total weight of the semi-solid aluminum-silicon alloy; And / or, in S2, the stirring is selected from at least one of mechanical stirring, ultrasonic vibration, electromagnetic stirring, tilted plate casting and air-cooled stirring; And / or, in S2, the solid phase ratio of the semi-solid slurry is 20-60%.

8. The die casting process according to claim 4, characterized in that: In S2, the temperature of the semi-solid alloy melt is reduced to 560-600° C.; And / or, in S3, the semi-solid alloy melt is sent to a pressure chamber at a temperature of 100-120°C, and then pressed into a mold at a temperature of 150-250°C for chilling and solidification; And / or, in S3, the quenching temperature is 20-50°C; And / or, the method of cooling the semi-solid alloy melt is selected from water cooling, oil cooling, gas cooling or salt bath cooling.

9. The die casting process according to claim 4, characterized in that: After S3, it also includes: S4, performing solution treatment, water quenching, aging treatment and air cooling on the aluminum-silicon alloy die casting; The temperature of the solution treatment is 525-545°C, and the time of the solution treatment is 2-3 hours; The temperature of the aging treatment is 155-175° C., and the time of the aging treatment is 0-10 hours.

10. An aluminum-silicon alloy, characterized in that: The method is prepared by the die-casting process as described in any one of claims 1 to 9.

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