Semi-solid casting method for rare earth alloying modified 3102 aluminum alloy

Abstract

The invention relates to the technical field of aluminum alloy casting, and discloses a rare earth alloying modified 3102 aluminum alloy semi-solid casting method which comprises the following steps: S1, preparing ingredients: firstly preparing a raw material of a 3102 aluminum alloy and then preparing a rare earth element, S2, smelting: sequentially putting the raw material of the 3102 aluminum alloy into smelting equipment according to a sequence, S3, adding the rare earth element, and S4, casting. After the 3102 aluminum alloy raw material is smelted, S4, preparing semi-solid slurry, namely, cooling and stirring a smelted solution through stirring equipment, and adding a grain refiner while stirring until the smelted solution is formed into the semi-solid slurry, S5, performing die casting or injection molding, injecting the semi-solid slurry into a die casting mold of die casting equipment, and S6, cooling and demolding. And S7, heat treatment is conducted, specifically, the demolded casting is subjected to solution treatment, and a protective atmosphere is added. The yield strength and tensile strength of the alloy are improved through mechanisms such as solid solution strengthening, copper and aluminum can form an intermetallic compound to achieve dispersion strengthening, hardness increasing and wear resistance improving, silicon is beneficial for reducing melt viscosity and improving fluidity, and the alloy body performance is further improved through mixing of multiple materials, and the alloy is suitable for being used in various scenes.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy casting, in particular to a semi-solid casting method of a rare earth alloyed modified 3102 aluminum alloy. Background Art

[0002] Rare earth alloying modified 3102 aluminum alloy is a technical means to improve the performance of 3102 aluminum alloy by adding rare earth elements. 3102 aluminum alloy is an aluminum-manganese series alloy, commonly used to manufacture aluminum materials with medium strength requirements. It has good corrosion resistance and formability and is widely used in construction, automobiles, home appliances and other industries. However, the strength, hardness and wear resistance of pure aluminum and its alloys are general and cannot meet the needs of high-performance applications. These properties can be effectively improved by alloying with rare earth elements.

[0003] Rare earth alloying modified 3102 aluminum alloy uses semi-solid casting method, mainly to give full play to the role of rare earth elements, improve the comprehensive performance of the alloy, and effectively avoid common defects in the casting process. Semi-solid casting is a casting technology between liquid and solid in the casting process. It usually controls the temperature to make the alloy in a partially solidified state, thereby obtaining a better casting effect than traditional casting methods.

[0004] Traditional aluminum alloy materials have certain limitations in some aspects. For example, the yield strength and tensile strength of some common aluminum alloys are relatively limited, and they are prone to deformation when subjected to large external forces. In terms of wear resistance, due to the lack of an effective strengthening mechanism, the surface hardness of the aluminum alloy is insufficient. In a working environment with relative friction contact, excessive wear will shorten the service life of components, increase maintenance costs and replacement frequency, and affect the overall operating efficiency and reliability of the equipment. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a semi-solid casting method for a rare earth alloyed modified 3102 aluminum alloy to solve the problems of low tensile strength and easy deformation; poor wear resistance and insufficient hardness and easy wear; poor toughness and easy brittle fracture under impact, and difficulty in meeting the requirements of strength, wear resistance and impact resistance under different working conditions.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] A rare earth alloy modified 3102 aluminum alloy semi-solid casting method comprises the following steps:

[0008] S1. Ingredient preparation: first prepare the raw materials of 3102 aluminum alloy, the raw materials of 3102 aluminum alloy include manganese, copper, iron, silicon, magnesium, and the rest is aluminum, and then prepare rare earth elements, the rare earth elements include neodymium, cerium and titanium;

[0009] S2, smelting, placing the 3102 aluminum alloy raw materials into the smelting equipment in order, heating them until they are completely melted to form aluminum alloy melt, and adding refining agent during the heating process;

[0010] S3, adding rare earth elements, after the 3102 aluminum alloy raw material is smelted, rare earth elements are added, then the temperature of the resistance furnace is increased, and then rare earth elements are added, and then stirred by a stirring device to make the rare earth elements and the refiner evenly distributed in the melt;

[0011] S4, semi-solid slurry preparation, the smelted solution is stirred while being cooled by a stirring device, and a grain refiner is added while stirring until a semi-solid slurry is formed;

[0012] S5, die casting or injection molding, injecting the semi-solid slurry into a die casting mold of a die casting device, adding a release agent to the inner side of the mold before injection, and die casting the semi-solid slurry;

[0013] S6, cooling and demoulding, cooling the formed casting to room temperature, and then demoulding and taking it out;

[0014] S7, heat treatment, the casting after demoulding is subjected to solution treatment, and a protective atmosphere is added, and after the solution treatment, water quenching is performed, and then heat preservation is performed.

[0015] Preferably, the raw materials of S1 and 3102 aluminum alloy have the following mass percentages: manganese 0.8-1.3%, copper 0.1-0.3%, iron 0.1-0.7%, silicon 0.3-0.7% and magnesium 0.1-0.3%, with the remainder being aluminum. The mass percentages of the various materials in the rare earth elements are 0.1-0.3% neodymium and 0.1-0.3% cerium, and titanium is used as a refiner, with an addition amount of 0.05-0.1%.

[0016] Preferably, in S2, the smelting equipment includes a resistance furnace, the heating temperature of the resistance furnace is 700-750°C, and the order of adding the materials is to first put the aluminum ingot into the resistance furnace to melt it completely, add manganese 5-10 minutes after the aluminum melts, stir evenly when the manganese is completely melted, and keep warm for 5-10 minutes, then add copper, stir evenly after the copper is completely melted, and keep warm for 3-5 minutes, then add silicon, stir evenly, and keep the temperature for 3-5 minutes, then add magnesium, stir evenly, and keep the temperature for 3-5 minutes, finally add iron, stir evenly, and keep the temperature for 3-5 minutes, and then add refining agent, the refining agent includes hexachloroethane or chlorine.

[0017] Preferably, in S3, the temperature of the resistance furnace is 720-730°C, the stirring device is an electromagnetic stirring device, the rotation speed of the electromagnetic stirring device is 200-300 rpm, and the order of adding the rare earth elements is to first add neodymium and stir at 200-250 rpm for 2-3 minutes, then add cerium and stir at 200-250 rpm for 2-3 minutes, and then add titanium and stir at 250-300 rpm for 1-2 minutes.

[0018] Preferably, in S4, the stirring equipment includes a stirrer, the stirring speed of the stirrer is 80-100 rpm, the stirring time is 15-20 minutes, the cooling rate during stirring is 10-20°C / minute for cooling, and then a grain refiner is added and stirred for 2-3 minutes, and cooled to 580-600°C until a semi-solid state is formed, the grain refiner includes an Al-Ti-B master alloy, and the addition amount of the Al-Ti-B master alloy accounts for 0.1-0.3% of the total mass, and the grain refiner is used to improve the mechanical properties and organizational uniformity of the casting.

[0019] Preferably, in S5, the die-casting pressure of the die-casting equipment is 80-100 MPa, the holding time is 10-15 seconds, and the release agent includes graphite powder or silicone oil. The release agent is used to improve the surface quality of the casting and the service life of the mold.

[0020] Preferably, in S6, the cooling method is water cooling, the water flow rate is 10-20 cubic meters per hour, the water temperature is 15-25°C, and the water spray pressure is 0.1-0.5 MPa.

[0021] Preferably, in S7, during the solution treatment, the casting is kept warm at a temperature of 530-550°C for 2-3 hours, and then water quenched at a temperature of 180-200°C for 8-10 hours. The protective atmosphere includes nitrogen or argon, and the protective atmosphere is used for heat treatment and surface quality.

[0022] The present invention provides a semi-solid casting method of rare earth alloyed modified 3102 aluminum alloy, which has the following beneficial effects:

[0023] 1. The present invention improves the yield strength and tensile strength of the alloy through mechanisms such as solid solution strengthening, making the casting less likely to deform when subjected to external force. Copper can form intermetallic compounds with aluminum to achieve dispersion strengthening, increase hardness, and improve wear resistance. Silicon helps to reduce melt viscosity and improve fluidity, which is beneficial to the smooth progress of subsequent casting processes. At the same time, it participates in the aging strengthening process to further enhance the strength and hardness of the alloy. Magnesium can not only enhance strength through solid solution strengthening, but also improve toughness, making the material less likely to break brittlely when impacted. The mixing of multiple materials further improves the performance of the alloy body and adapts to the effect of use in various scenarios.

[0024] 2. The present invention can effectively remove inclusions and gas impurities such as hydrogen in the aluminum alloy melt by adding a refining agent, purify the melt, improve the purity of the aluminum alloy, and further improve the internal quality of the casting, reduce defects caused by impurities such as pores and slag inclusions, and make the casting have higher performance.

[0025] 3. The present invention adds AlTiB intermediate alloy as a grain refiner, which can further refine the grains, improve the mechanical properties of the casting, enhance the strength, toughness and organizational uniformity, make the casting denser in microstructure and more stable in performance, and help meet the requirements of casting quality in different usage scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a method flow chart of a rare earth alloying modified 3102 aluminum alloy semi-solid casting method. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings 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 are within the scope of protection of the present invention.

[0028] Example:

[0029] Please refer to the attached Figure 1 The embodiment of the present invention provides a rare earth alloying modified 3102 aluminum alloy semi-solid casting method, comprising the following steps:

[0030] S1. Ingredient preparation: first prepare the raw materials of 3102 aluminum alloy, which include manganese, copper, iron, silicon, magnesium, and the rest is aluminum, and then prepare rare earth elements, which include neodymium, cerium and titanium;

[0031] S2, smelting, placing the 3102 aluminum alloy raw materials into the smelting equipment in order, heating them until they are completely melted to form aluminum alloy melt, and adding refining agent during the heating process;

[0032] S3, adding rare earth elements, after the 3102 aluminum alloy raw material is smelted, rare earth elements are added, then the temperature of the resistance furnace is increased, and then rare earth elements are added, and then stirred by a stirring device to make the rare earth elements and the refiner evenly distributed in the melt;

[0033] S4, semi-solid slurry preparation, the smelted solution is stirred while being cooled by a stirring device, and a grain refiner is added while stirring until a semi-solid slurry is formed;

[0034] S5, die casting or injection molding, injecting the semi-solid slurry into a die casting mold of a die casting device, adding a release agent to the inner side of the mold before injection, and die casting the semi-solid slurry;

[0035] S6, cooling and demoulding, cooling the formed casting to room temperature, and then demoulding and taking it out;

[0036] S7, heat treatment, the casting after demoulding is subjected to solution treatment, and a protective atmosphere is added, and after the solution treatment, water quenching is performed, and then heat preservation is performed.

[0037] The raw materials of S1 and 3102 aluminum alloys are 0.8-1.3% manganese, 0.1-0.3% copper, 0.1-0.7% iron, 0.3-0.7% silicon and 0.1-0.3% magnesium by mass, and the rest is aluminum. The mass percentages of various materials in the rare earth elements are 0.1-0.3% neodymium and 0.1-0.3% cerium, and titanium is used as a refiner, with an addition amount of 0.05-0.1%.

[0038] Specifically, manganese in 3102 aluminum alloy can be integrated into the aluminum lattice structure by solid solution strengthening, increasing the degree of lattice distortion, thereby effectively improving the strength of the aluminum alloy. In some application scenarios of aluminum alloy plates that need to withstand certain external forces, the appropriate content of manganese can ensure that the plates are not easily deformed during processing and use, and maintain the stability of the structure. Manganese can also improve the corrosion resistance of aluminum alloys. It can form a relatively stable oxide film on the surface of the aluminum alloy to prevent external corrosive media from further corroding the base metal. This can extend the service life and reduce maintenance costs for aluminum alloy products such as outdoor architectural decorations, or some aluminum alloy parts used in slightly corrosive environments;

[0039] Copper is an effective alloying element. It can form a variety of intermetallic compounds with aluminum. These compounds will be dispersed in the matrix during the solidification process of aluminum alloy, playing a role of dispersion strengthening, further improving the mechanical properties of aluminum alloy, and increasing the hardness of the material. It is suitable for some applications that have certain requirements for wear resistance, such as aluminum alloy guide rails used in industrial conveying equipment. The presence of copper helps to improve its wear resistance.

[0040] Iron is usually regarded as an impurity element in aluminum alloys. However, within a certain content range, it can interact with other elements and affect the structure and properties of aluminum alloys. For example, iron can combine with elements such as manganese to form some fine intermetallic compounds. If these compounds are evenly distributed, they can refine the grain structure to a certain extent and play a role similar to that of a refiner. Of course, its effect is weaker than that of a special refiner, but it still makes a certain contribution to improving the overall performance of aluminum alloys.

[0041] Silicon is an extremely important element for improving casting performance. When casting aluminum alloys, it can significantly reduce the viscosity of the melt, improve the fluidity of the molten metal, make it easier for the molten metal to fill complex mold cavities, and reduce the probability of casting defects such as pores and shrinkage holes. For example, when manufacturing aluminum alloy die castings with complex shapes, the presence of silicon can ensure the integrity and appearance quality of the castings and improve the yield rate;

[0042] After magnesium is added, it can form a solid solution with aluminum, and enhance the strength of aluminum alloy through solid solution strengthening. At the same time, it can also improve the toughness of aluminum alloy to a certain extent, so that the material is not prone to brittle fracture when subjected to external impact, but has a certain plastic deformation ability. This comprehensive improvement in strength and toughness makes aluminum alloy perform well in application scenarios such as some non-critical structural parts of automobile bodies and electronic equipment casings that require both certain strength and impact resistance.

[0043] Neodymium has a significant metamorphic effect. It can change the shape and distribution of inclusions in aluminum alloys, transforming them from coarse and irregular shapes that may have an adverse effect on material properties to fine, dispersed and relatively evenly distributed. For example, during the casting process, neodymium can refine some non-metallic inclusions in aluminum alloys, thereby reducing the possibility of these inclusions acting as stress concentration points and causing defects such as cracks, thereby improving the quality and reliability of castings;

[0044] Cerium can effectively refine the grains. During the solidification process of aluminum alloy, it will concentrate at the grain boundaries, which will hinder the growth of grains on the one hand, and on the other hand, it can serve as the core of heterogeneous nucleation, prompting the aluminum alloy to form more, finer and evenly distributed grains. This refined grain structure can greatly improve the comprehensive mechanical properties of aluminum alloys, such as strength, toughness and fatigue resistance. It can help improve the performance and life of various aluminum alloy products, whether they are castings or deformed parts.

[0045] Titanium is an effective refiner, mainly through the formation of some high melting point compounds, such as TiAl3, etc. These compounds can serve as the core of heterogeneous nucleation when the aluminum alloy melt solidifies, providing more nucleation sites for the crystallization of aluminum atoms, thereby promoting the formation of fine and evenly distributed grain structure of aluminum alloy. Compared with other refiners, titanium has a more stable refinement effect, and can play a better role under different cooling conditions and process parameters, ensuring that the grain refinement effect of aluminum alloy is achieved.

[0046] In S2, the smelting equipment includes a resistance furnace, the heating temperature of the resistance furnace is 700-750°C, and the order of adding materials is to first put the aluminum ingot into the resistance furnace to melt it completely, add manganese 5-10 minutes after the aluminum melts, stir evenly when the manganese is completely melted, and keep warm for 5-10 minutes, then add copper, stir evenly after the copper is completely melted, and keep warm for 3-5 minutes, then add silicon, stir evenly, and keep the temperature for 3-5 minutes, then add magnesium, stir evenly, and keep the temperature for 3-5 minutes, finally add iron, stir evenly, and keep the temperature for 3-5 minutes, then add refining agent, the refining agent includes hexachloroethane or chlorine.

[0047] Specifically, first put the aluminum ingot into the resistance furnace. The reason for adding the aluminum ingot first is that aluminum is the matrix element in the 3102 aluminum alloy and accounts for the vast majority of the content. At a heating temperature of 700-750°C, the aluminum ingot will gradually melt. In this process, as the temperature rises, the aluminum ingot changes from solid to liquid, and the heat is transferred from the heating element of the resistance furnace to the surface of the aluminum ingot, and then gradually conducted to the inside, making it melt evenly as a whole. When the aluminum is completely melted, it creates a good liquid environment for the subsequent addition and dissolution of other elements, because liquid aluminum can better mix and alloy with other elements;

[0048] Wait 5-10 minutes after the aluminum is completely melted before adding manganese. This is because the aluminum melt needs a certain amount of time to stabilize its temperature and fluidity, so that the manganese element can be better integrated in the future. The melting point of manganese is relatively high. After adding it, it needs to rely on the heat of the aluminum melt to melt it. During this period of time, through proper stirring (stirring can be done with a mechanical stirring rod or an electromagnetic stirring device. The mechanical stirring rod is generally made of high-temperature resistant graphite materials, etc., and can work stably in high-temperature aluminum melts. Electromagnetic stirring uses the Lorentz force generated by the principle of electromagnetic induction to drive the melt flow to achieve the stirring effect. The stirring speed can be adjusted between tens to hundreds of revolutions per minute according to actual conditions), the melting speed of manganese can be accelerated, so that it is evenly dispersed in the aluminum melt to form a uniform alloy solution. The operation of keeping warm for 5-10 minutes is to ensure that manganese is completely melted and fully alloyed with aluminum, to avoid the occurrence of locally unmelted manganese particles or uneven alloy composition, which is conducive to the subsequent addition of other elements and to ensure the stability of the quality of the entire alloy.

[0049] When the manganese is completely melted, stirred evenly, and the heat preservation is completed, copper is then added. After the copper is added, it also relies on the heat of the aluminum melt to melt. Since the melting point of copper is also relatively high, continuous stirring during its melting process can make the copper element more evenly dispersed in the alloy melt faster and improve the alloying efficiency. The step of keeping warm for 3-5 minutes, on the one hand, ensures that the copper is completely melted, and on the other hand, allows the copper to further react and diffuse with the existing aluminum and manganese elements to form a stable alloy phase structure, laying the foundation for the subsequent addition of other elements to further improve the alloy composition, so that the final 3102 aluminum alloy has a more even distribution of components, and better performance in various aspects such as mechanical properties;

[0050] Then silicon is added. Silicon has the function of reducing melt viscosity and improving fluidity in aluminum alloy smelting. After being added, it can be quickly dispersed in the alloy melt by stirring evenly and maintaining the temperature for 3-5 minutes. In this process, silicon will better interact with other elements and participate in the formation of the solidification structure of the alloy. For example, it helps to improve the filling capacity of the molten metal during the subsequent casting of aluminum alloy and reduce the possibility of casting defects. It also has a positive effect on the performance improvement of aluminum alloy such as aging strengthening, ensuring that the smelted aluminum alloy can meet the subsequent different processing and use requirements;

[0051] After the addition of magnesium, in addition to enhancing the strength and toughness of aluminum alloys through solid solution strengthening and other methods, it also plays an important role in the surface treatment of aluminum alloys. Therefore, it is very important to ensure its uniform dispersion and full alloying with other elements. Only in this way can the advantages of magnesium be fully utilized in the subsequent processing and use of aluminum alloy products to improve the overall quality of the product.

[0052] The addition of iron and subsequent operations combined with elements such as manganese to form some special compounds participate in the process of grain structure regulation of the alloy, contribute to improving the comprehensive performance of the aluminum alloy, and ensure that the smelted 3102 aluminum alloy meets the established composition requirements and performance standards.

[0053] After all the main ingredients are added and the corresponding operations are completed, a refining agent is added. The refining agent mentioned here includes hexachloroethane or chlorine. 2 Cl 6 ) will decompose in high-temperature aluminum melt to produce some gases (such as chlorine, aluminum chloride, etc.). These gases form a large number of tiny bubbles in the melt. In the process of the bubbles floating up, they can absorb some inclusions and gas impurities (such as hydrogen, etc.) in the melt and bring them to the surface of the melt, thereby achieving the purpose of removing impurities and purifying the melt. Chlorine (Cl 2 ) itself is a strong oxidizing gas. After being introduced into the aluminum melt, it can also react chemically with some impurity elements in the melt to generate compounds that are easy to float up and discharge, thereby achieving the refining of the melt and improving the purity of the aluminum alloy, which provides a guarantee for the subsequent high-quality casting and processing of the aluminum alloy and the good performance of the final product. However, when using hexachloroethane or chlorine, appropriate ventilation and protective measures must be taken, because the gases produced by their decomposition or reaction may be harmful to the health of operators and the environment. It is necessary to ensure that the refining operation is carried out under conditions that meet safety and environmental protection requirements.

[0054] In S3, the temperature of the resistance furnace is 720-730°C, the stirring device is an electromagnetic stirring device, the rotation speed of the electromagnetic stirring device is 200-300 rpm, and the order of adding rare earth elements is to first add neodymium and then stir at 200-250 rpm for 2-3 minutes, then add cerium and stir at 200-250 rpm for 2-3 minutes, and then add titanium and stir at 250-300 rpm for 1-2 minutes.

[0055] Specifically, the temperature of the resistance furnace is set in a relatively more precise range of 720-730℃. For the smelting of various components of 3102 aluminum alloy, this temperature range can not only ensure that the main elements (such as aluminum, manganese, copper, silicon, magnesium, iron, etc.) are fully melted and quickly alloyed, but also avoid some problems that may be caused by excessively high temperature to a certain extent;

[0056] The electromagnetic stirring device is a device that uses the principle of electromagnetic induction to stir the aluminum alloy melt. When an alternating current is passed through, an alternating magnetic field is generated around the melt. The charged particles in the melt (such as aluminum ions, etc.) move in a directional manner under the action of the Lorentz force, thereby driving the entire melt to flow in a regular manner to achieve a stirring effect. Compared with traditional mechanical stirring methods, electromagnetic stirring has the advantages of more uniform stirring, no introduction of additional impurities (mechanical stirring rods may wear and drop debris, etc.), and flexible adjustment of stirring intensity.

[0057] In this speed range, the melt can form a relatively stable and reasonable flow state, and each element can diffuse quickly and evenly in the aluminum melt, accelerating the alloying process. For example, after adding manganese, stirring at a speed of 200-300 rpm, manganese particles can melt faster and disperse evenly in the aluminum melt, effectively ensuring the uniformity of the composition of the entire alloy melt, laying the foundation for the subsequent addition of other elements and the smooth formation of high-quality 3102 aluminum alloy.

[0058] The reason why neodymium is added first is that neodymium can first play its modifying role in 3102 aluminum alloy, changing the morphology and distribution of inclusions. At this specific stirring speed and time, the neodymium element can be fully dispersed in the melt and interact with the existing alloy components;

[0059] Then, cerium is added. Cerium mainly plays a role in grain refinement. At this rotation speed and stirring time, cerium can be evenly distributed in the melt. In the process of its segregation to the grain boundary and hindering grain growth and acting as a heterogeneous nucleation core, the appropriate stirring operation ensures that it can be in a good dispersion state in the melt, and synergizes with other elements and neodymium to promote the aluminum alloy to form more, finer and evenly distributed grains.

[0060] The purpose of adding titanium element finally is to disperse it quickly and evenly in the melt containing neodymium and cerium in a relatively short time, so that it can quickly interact with other elements to form effective nucleation points and play the best role in grain refinement.

[0061] In S4, the stirring device includes a stirrer, the stirring speed of the stirrer is 80-100 rpm, the stirring time is 15-20 minutes, the cooling rate during stirring is 10-20°C / minute, and then a grain refiner is added and stirred for 2-3 minutes, and cooled to 580-600°C until a semi-solid state is formed. The grain refiner includes an AlTiB master alloy, and the addition amount of the AlTiB master alloy accounts for 0.1-0.3% of the total mass. The grain refiner is used to improve the mechanical properties and organizational uniformity of the casting.

[0062] Specifically, a moderate stirring speed can prevent violent splashing of the melt, increased oxidation, and the entrainment of too much air, while ensuring that the melt has sufficient flow strength in the mixing barrel, promoting a more uniform distribution of internal components and temperature, etc. This allows the various components in the melt to be further fully mixed, laying the foundation for the stability and improvement of the aluminum alloy performance in the subsequent process, and ensuring that the subsequent added substances can better interact with it;

[0063] The stirring time is given enough time to allow the mixer to fully exert its stirring effect, so that the melt undergoes multiple circulations and mixing, improves the uneven composition phenomenon, and reduces the temperature difference in different areas. The physical and chemical state of the entire melt is more uniform, creating good conditions for the uniform dispersion of the grain refiner, ensuring that it can effectively play a role in improving the performance of castings;

[0064] The cooling rate controls the growth morphology and growth rate of the crystals in the aluminum alloy melt during the cooling process, preventing the crystals from growing too fast to form a coarse grain structure, and promoting the formation of small and evenly distributed crystal nuclei. This helps to obtain a good semi-solid structure, ensures that subsequent processing can proceed smoothly, and is conducive to the manufacture of casting products with good internal structure quality;

[0065] Grain refiner uses the TiB it contains 2 、TiAl 3 Compounds such as aluminum and aluminum oxide serve as heterogeneous nucleation cores, providing appropriate nucleation sites for aluminum atom crystallization, and refining grains without introducing too many impurities or affecting the normal solidification of the melt and subsequent processing performance. Significantly improve the mechanical properties of castings, including improving strength indicators such as tensile strength and yield strength, enhancing material toughness, and reducing the risk of brittle fracture; at the same time, improve organizational uniformity, avoid performance instability caused by local grain differences, ensure reliable performance of different parts of the casting, good dimensional accuracy and appearance quality, and meet the production needs of high-performance castings;

[0066] Cooling to 580-600℃ to form a semi-solid state makes the aluminum alloy melt reach an ideal semi-solid state with unique rheological properties, such as good fluidity and thixotropy. In subsequent molding processes (such as die casting, rheological casting, etc.), it can better fill the mold cavity, help to manufacture castings with complex shapes, high dimensional accuracy and dense internal structure, improve the quality and comprehensive performance of castings, and adapt to diversified industrial application scenarios.

[0067] In S5, the die-casting pressure of the die-casting equipment is 80-100MPa, the holding time is 10-15 seconds, and the release agent includes graphite powder or silicone oil. The release agent is used to improve the surface quality of the casting and the service life of the mold.

[0068] Specifically, the die-casting pressure of the die-casting equipment pushes the semi-solid aluminum alloy melt to quickly and evenly fill the die-casting mold cavity, overcome flow resistance, replicate precise shapes and contours, and improve melt density and reduce internal defects. The casting has high dimensional accuracy, enhanced mechanical properties, improved load-bearing and durability, and extended service life;

[0069] The holding time of the die-casting equipment compensates for the shrinkage of the solidified melt, maintains the shape stability, and prevents shrinkage holes, deformation, and uneven wall thickness. It improves the yield rate, reduces the scrap rate, saves costs, and the casting has a good appearance quality that meets the design requirements;

[0070] The release agent forms an isolation film between the casting and the mold to prevent adhesion and scratches, improve the surface quality of the casting, reduce mold wear and chemical erosion, and extend the life of the mold. The casting has a beautiful appearance, which is conducive to subsequent surface treatment, reduces the frequency of mold maintenance and replacement, and ensures efficient and stable die-casting production.

[0071] In S6, water cooling is adopted for cooling, the water flow rate is 10-20 cubic meters / hour, the water temperature is 15-25℃, and the water spray pressure is 0.1-0.5 MPa.

[0072] Specifically, the heat of the casting is taken away by the flow of water, which can achieve rapid cooling and allow the casting to cool from the high temperature state after die-casting to the appropriate temperature as soon as possible, which helps to stabilize the internal structure of the casting and prevent abnormal grain growth due to long-term high temperature. The coordination of appropriate parameters such as water flow, water temperature and water spray pressure can effectively regulate the cooling rate, allow all parts of the casting to cool evenly, and avoid thermal stress concentration caused by excessive local cooling, which in turn causes defects such as cracking and deformation of the casting. In terms of ensuring the quality of castings: the castings can obtain good internal structures, ensure that their mechanical properties are stable, and indicators such as strength and hardness meet the requirements, while reducing casting defects and improving product qualification rates. In terms of improving production efficiency: the relatively fast cooling rate can shorten the production cycle, speed up the turnover of castings, improve the efficiency of the entire die-casting production process, and meet the needs of mass production.

[0073] In S7, during the solution treatment, the casting is kept at 530-550°C for 2-3 hours, and then water quenched at 180-200°C for 8-10 hours. The protective atmosphere includes nitrogen or argon, and the protective atmosphere is used for heat treatment and surface quality.

[0074] Specifically, solution treatment is carried out in this temperature range to fully dissolve the alloy elements inside the casting into the aluminum matrix to form a uniform solid solution, which helps to eliminate the structural inhomogeneities such as segregation produced during the casting process and optimize the microstructure of the casting. The appropriate holding time ensures sufficient atomic diffusion process, allowing the various phases to be fully homogenized, laying the foundation for the subsequent improvement of the mechanical properties of the casting. After this treatment, the strength, hardness and other mechanical performance indicators of the casting can be significantly improved, so that it can better meet the requirements of load-bearing in actual use. For example, aluminum alloy castings used in mechanical structures can withstand greater external forces;

[0075] The water quenching temperature is 180-200℃, and the insulation time is 8-10 hours. Water quenching is a rapid cooling heat treatment method. By quickly placing the high-temperature castings in water at a specific temperature of 180-200℃ for insulation, the solid solution state formed at high temperature can be fixed, inhibiting the precipitation of alloy elements, obtaining a supersaturated solid solution, further strengthening the alloy, and improving its strength, hardness and other properties. The combination of specific water quenching temperature and insulation time can effectively control the magnitude of thermal stress generated inside the casting, avoid defects such as cracking of the casting due to excessive quenching stress, and ensure the smooth progress of the quenching process. The mechanical properties of the castings are significantly improved, especially the strength and hardness are significantly improved, making it more applicable in some occasions with high requirements for wear resistance and deformation resistance, such as aluminum alloy application scenarios in some moving parts;

[0076] Protective atmosphere in heat treatment: Protective atmospheres such as nitrogen or argon can isolate the air, prevent the casting from oxidizing with oxygen in the air during high-temperature solution treatment, avoid the formation of an oxide film on the surface of the casting, ensure that the surface composition and internal structure of the casting after heat treatment are not affected by oxidation, and maintain the ideal heat treatment effect. It effectively avoids problems such as surface roughness and discoloration caused by oxidation, keeps the surface of the casting smooth, and provides a good foundation for subsequent possible surface treatments such as electroplating and spraying, improves the appearance quality of the casting, and enhances the market competitiveness of the product. The surface of the casting after heat treatment is bright and free of oxide layer, and its internal structure and performance are optimized as expected, ensuring the overall quality of the product, so that it can show good performance and appearance in various application scenarios, and improves the product's qualification rate and market recognition.

[0077] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A semi-solid casting method for rare earth alloyed modified 3102 aluminum alloy, characterized in that: The following steps are involved: S1. Ingredient preparation: first prepare the raw materials of 3102 aluminum alloy, the raw materials of 3102 aluminum alloy include manganese, copper, iron, silicon, magnesium, and the rest is aluminum, and then prepare rare earth elements, the rare earth elements include neodymium, cerium and titanium; S2, smelting, placing the 3102 aluminum alloy raw materials into the smelting equipment in order, heating them until they are completely melted to form aluminum alloy melt, and adding refining agent during the heating process; S3, adding rare earth elements, after the 3102 aluminum alloy raw material is smelted, rare earth elements are added, then the temperature of the resistance furnace is increased, and then rare earth elements are added, and then stirred by a stirring device to make the rare earth elements and the refiner evenly distributed in the melt; S4, semi-solid slurry preparation, the smelted solution is stirred while being cooled by a stirring device, and a grain refiner is added while stirring until a semi-solid slurry is formed; S5, die casting or injection molding, injecting the semi-solid slurry into a die casting mold of a die casting device, adding a release agent to the inner side of the mold before injection, and die casting the semi-solid slurry; S6, cooling and demoulding, cooling the formed casting to room temperature, and then demoulding and taking it out; S7, heat treatment, the casting after demoulding is subjected to solution treatment, and a protective atmosphere is added, and after the solution treatment, water quenching is performed, and then heat preservation is performed.

2. The semi-solid casting method of rare earth alloyed modified 3102 aluminum alloy according to claim 1, characterized in that: The raw materials of S1 and 3102 aluminum alloys have the following mass percentages: manganese 0.8-1.3%, copper 0.1-0.3%, iron 0.1-0.7%, silicon 0.3-0.7% and magnesium 0.1-0.3%, with the remainder being aluminum. The mass percentages of the various materials in the rare earth elements are 0.1-0.3% of neodymium and 0.1-0.3% of cerium, and titanium is used as a refiner, with an addition amount of 0.05-0.1%.

3. The semi-solid casting method of rare earth alloyed modified 3102 aluminum alloy according to claim 1, characterized in that: In S2, the smelting equipment includes a resistance furnace, the heating temperature of the resistance furnace is 700-750°C, and the order of adding the materials is to first put the aluminum ingot into the resistance furnace to completely melt it, add manganese 5-10 minutes after the aluminum melts, stir evenly when the manganese is completely melted, and keep warm for 5-10 minutes, then add copper, stir evenly after the copper is completely melted, and keep warm for 3-5 minutes, then add silicon, stir evenly, and keep the temperature for 3-5 minutes, then add magnesium, stir evenly, and keep the temperature for 3-5 minutes, finally add iron, stir evenly, and keep the temperature for 3-5 minutes, and then add refining agent, the refining agent includes hexachloroethane or chlorine.

4. The semi-solid casting method of rare earth alloyed modified 3102 aluminum alloy according to claim 1, characterized in that: In S3, the temperature of the resistance furnace is 720-730°C, the stirring device is an electromagnetic stirring device, the rotation speed of the electromagnetic stirring device is 200-300 rpm, and the order of adding the rare earth elements is to first add neodymium and then stir at 200-250 rpm for 2-3 minutes, then add cerium and stir at 200-250 rpm for 2-3 minutes, and then add titanium and stir at 250-300 rpm for 1-2 minutes.

5. The semi-solid casting method of rare earth alloyed modified 3102 aluminum alloy according to claim 1, characterized in that: In S4, the stirring device includes a stirrer, the stirring speed of the stirrer is 80-100 rpm, the stirring time is 15-20 minutes, the cooling rate during stirring is 10-20°C / minute for cooling, and then a grain refiner is added and stirred for 2-3 minutes, and cooled to 580-600°C until a semi-solid state is formed, the grain refiner includes an Al-Ti-B master alloy, and the addition amount of the Al-Ti-B master alloy accounts for 0.1-0.3% of the total mass, and the grain refiner is used to improve the mechanical properties and organizational uniformity of the casting.

6. The semi-solid casting method of rare earth alloyed modified 3102 aluminum alloy according to claim 1, characterized in that: In S5, the die-casting pressure of the die-casting equipment is 80-100 MPa, the holding time is 10-15 seconds, and the release agent includes graphite powder or silicone oil. The release agent is used to improve the surface quality of the casting and the service life of the mold.

7. The semi-solid casting method of rare earth alloyed modified 3102 aluminum alloy according to claim 1, characterized in that: In S6, the cooling method adopts water cooling, the water flow rate is 10-20 cubic meters / hour, the water temperature is 15-25°C, and the water spray pressure is 0.1-0.5 MPa.

8. The semi-solid casting method of rare earth alloyed modified 3102 aluminum alloy according to claim 1, characterized in that: In S7, during the solution treatment, the casting is kept warm at a temperature of 530-550°C for 2-3 hours, and then water quenched at a temperature of 180-200°C for 8-10 hours. The protective atmosphere includes nitrogen or argon, and the protective atmosphere is used for heat treatment and surface quality.

Images