Method for enhancing aluminum-magnesium heat-treatment-free die-casting aluminum alloy through cooperation of electromagnetic field and TiCN

Abstract

The invention discloses a method for heat-treatment-free die-casting of an aluminum alloy by reinforcing aluminum and magnesium through cooperation of an electromagnetic field and TiCN, and relates to the technical field of high-performance aluminum alloy die-casting. According to the method for heat treatment-free die casting of the aluminum alloy through the cooperation of the electromagnetic field and the TiCN reinforced aluminum magnesium, the electromagnetic stirring technology and the TiCN refiner are innovatively introduced into the aluminum magnesium alloy die casting process, and through the synergistic effect of the electromagnetic field and the refining phase, the uniformity and the grain refining effect of alloy liquid are remarkably improved; and a high-strength and high-toughness as-cast structure can be obtained under a heat-treatment-free condition. The method not only solves the problems of high energy consumption, long period, easy deformation and the like of the traditional heat treatment process, but also greatly improves the production efficiency and the product consistency, has remarkable practical value and popularization prospect, and is particularly suitable for the fields of new energy automobiles, aerospace and the like with strict requirements on light weight and performance.

Description

Technical Field

[0001] This application belongs to the field of high-performance aluminum alloy die casting, and particularly relates to a method for electromagnetic field-assisted TiCN-reinforced heat-free die-cast aluminum-magnesium alloy. Background Technology

[0002] In recent years, with the increasing demand for high-performance aluminum alloys in fields such as automotive lightweighting and aerospace, die-cast heat-treatable aluminum alloys have become a research hotspot. In contrast, traditional die-cast aluminum alloys have certain limitations. While traditional die-cast aluminum alloys, such as Al-Si alloys, possess good casting and mechanical properties, heat treatment is usually required to further improve their strength, hardness, and other properties. However, heat treatment processes have the following limitations: heat treatment requires specialized equipment, consumes a lot of energy, and involves complex processes, leading to increased production costs. The heat treatment process is time-consuming, affecting production efficiency. Deformation is easily generated during heat treatment, affecting the dimensional accuracy and surface quality of castings. The heat treatment process consumes a large amount of energy, which is inconsistent with the development trend of green manufacturing. Heat-treatable aluminum alloys refer to aluminum alloys that can obtain good mechanical properties in the as-cast state through alloy composition optimization, melt treatment, and microstructure control. Their advantages are mainly reflected in: eliminating the heat treatment process, simplifying the production flow, and reducing production costs; improving production efficiency and shortening product delivery cycles; avoiding the deformation risk during heat treatment, and improving the dimensional accuracy and surface quality of castings. It aligns with the development trend of green manufacturing, reducing energy consumption and environmental pollution. Summary of the Invention

[0003] To address some or all of the technical problems existing in the prior art, this application provides a method for electromagnetic field-assisted TiCN-reinforced heat-free die-cast aluminum-magnesium alloy.

[0004] This application provides a method for electromagnetic field-assisted TiCN-reinforced heat-free die-cast aluminum-magnesium alloy, comprising the following steps: S1. Make preliminary preparations, inspect and clean the smelting equipment, ensure that the power supply and temperature measurement system are normal, and eliminate the risk of leakage. S2. Preheat the die-casting mold and the pressure chamber runner to 200°C, and spray with boron nitride release agent; S3. Perform surface polishing, alcohol cleaning and 100℃ drying on aluminum alloy raw materials; S4. Crush some alloy ingots into blocks, add them to a crucible along with pure Al, Al-40Si, and Al-10Mn, melt them at 760℃ and hold for 20 minutes. S5. When the alloy liquid cools down to 720℃, add pure Mg. After the reaction is complete, remove the slag. S6. Add TiCN refiner and homogenize the alloy liquid using an electromagnetic stirring device; S7. Finally, die casting is performed, with the casting temperature controlled at 700℃ and the injection time at 3 seconds. After the mold cools, the aluminum-magnesium alloy casting is removed.

[0005] Preferably, the aluminum-magnesium alloy has the following weight percentages: Mg: 6.5%–7.0%, Si: 2.0%–2.5%, Mn: 0.6%, Fe: 0.15%, TiCN: 0.3wt.%, with the balance being Al.

[0006] Preferably, the die-casting mold and gating system need to be preheated to above 200°C, and boron nitride release agent is evenly applied to the surface of the mold.

[0007] Preferably, the aluminum alloy raw material must be polished by a sand mill to remove the oxide layer, cleaned with alcohol, and then dried in an oven at 100°C.

[0008] Preferably, the die-casting temperature is controlled at 700–720°C.

[0009] Preferably, the die-casting process adopts a pressure boosting mode, and the injection time is 3 seconds.

[0010] Preferably, the parameters of the electromagnetic stirring device are set as follows: stirring frequency 5–50Hz, stirring voltage 0–380V, and stirring time 600 seconds.

[0011] The method for electromagnetic field-assisted TiCN-reinforced heat-free die-cast aluminum-magnesium alloys in this application has the following advantages and positive effects: Compared with existing heat-free aluminum alloy technologies, this invention innovatively introduces electromagnetic stirring technology and TiCN grain refiner into the die-casting process of aluminum-magnesium alloys. Through the synergistic effect of the electromagnetic field and the refining phase, the uniformity of the alloy melt and the grain refinement effect are significantly improved, resulting in a high-strength and high-toughness as-cast microstructure without heat treatment. This method not only solves the problems of high energy consumption, long cycle time, and easy deformation in traditional heat treatment processes, but also significantly improves production efficiency and product consistency. It has significant practical value and promising prospects, and is particularly suitable for fields with stringent requirements for lightweighting and performance, such as new energy vehicles and aerospace. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for further understanding of the embodiments of this application and constitute a part of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1This is a process flow diagram of the electromagnetic field-assisted TiCN-reinforced heat-free die-cast aluminum-magnesium alloy method of this application; Figure 2 This is a schematic diagram of the electromagnetic stirring device of this application.

[0013] Explanation of reference numerals in the attached figures: 1-Graphite inner liner, 2-Sealing cap, 3-Thermocouple, 4-Fused material. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0015] Example 1: This embodiment prepares an aluminum-magnesium alloy with synergistic enhancement by electromagnetic stirring and TiCN refining. The weight percentages of its components are: Mg: 6.5%, Si: 2.5%, Mn: 0.6%, Fe: 0.15%, and 0.3 wt.% TiCN refining agent is added, with the balance being Al and unavoidable impurities.

[0016] like Figure 1As shown, the specific preparation and die-casting process includes the following steps: First, preliminary preparations are made, including checking the condition of the melting equipment, cleaning the splashed debris in the furnace and the residual metal fragments in the crucible to ensure a clean melting environment, preventing impurities from mixing into the alloy liquid, avoiding contamination and inclusion formation, and ensuring alloy purity. Simultaneously, equipment safety is checked to avoid potential hazards such as electrical leakage and improve operational reliability. The power lines and temperature measuring devices of the melting equipment are checked to ensure accuracy and reliability, and potential electrical leakage hazards are eliminated. Precise temperature control and process safety are guaranteed; accurate temperature measurement is key to controlling the melting process and avoiding temperature fluctuations that affect alloy quality. The die-casting mold and pressure chamber gating are preheated to 200℃, and it is confirmed that the mold surface has been sprayed with boron nitride release agent. Preheating the mold reduces thermal shock and prevents casting cracking or deformation; spraying the release agent facilitates demolding, improves the surface quality of the casting, and reduces defects. The aluminum alloy raw materials undergo surface treatment. The oxide layer is removed by sand milling, followed by cleaning with alcohol and drying in a 100℃ oven. This process removes the oxide layer and absorbed moisture from the raw material surface, preventing porosity and oxide inclusions during melting, and improving the alloy's density and mechanical properties. Some alloy ingots are broken into blocks to facilitate faster melting into molten aluminum, increasing the raw material surface area, accelerating the melting process, improving melting efficiency, and reducing energy consumption. Pure Al, Al-40Si, and Al-10Mn are added to a crucible and heated to 760℃ to melt. The temperature is held for 20 minutes. Pure Al serves as the matrix, while Al-40Si and Al-10Mn act as intermediate alloys, facilitating the dissolution and uniform distribution of Si and Mn elements. Melting at 760℃ and holding ensures complete melting and initial homogenization of the alloy elements, preparing for the subsequent addition of Mg. When the alloy melt temperature drops to 720℃, pure Mg is added. After sufficient reaction, surface slag is removed. Mg is easily oxidized, so adding it at a lower temperature (720℃) reduces burn-off and oxidation. Slag removal removes surface oxides and impurities, improving alloy cleanliness. Subsequently, TiCN grain refiner is added, and an electromagnetic stirrer is activated to homogenize the alloy melt. The stirring frequency is set to 55Hz, the stirring voltage to 380V, and the total stirring time to 600 seconds, consisting of 60 seconds of forward rotation, 60 seconds of reverse rotation, with a 10-second interval. The TiCN grain refiner acts as a heterogeneous nucleation core, promoting grain refinement. Electromagnetic stirring breaks dendrites and promotes uniform solute distribution through Lorentz force, reducing segregation. The alternating forward and reverse stirring prevents vortex formation and ensures overall homogenization. This step is a key synergistic process for obtaining fine equiaxed grains. Finally, die casting is performed, controlling the casting temperature at 700℃. Safety precautions must be taken during casting. A casting temperature of 700℃ ensures good alloy fluidity, complete mold filling, and reduces cold shuts and shrinkage cavities. Die casting allows for rapid solidification, further refining the microstructure. After the mold cools down, the ingot is removed from the mold and allowed to cool naturally to avoid residual stress, thus obtaining a casting with stable dimensions.

[0017] Through the above process, the aluminum-magnesium alloy obtained in this embodiment has excellent as-cast properties and can meet the high performance requirements without any heat treatment: tensile strength: ≥320MPa, yield strength: ≥180MPa, elongation: ≥10%.

[0018] Example 2: like Figure 1 As shown, this embodiment prepares an aluminum-magnesium alloy with synergistic enhancement by electromagnetic stirring and TiCN refining. The weight percentages of its components are: Mg: 7.0%, Si: 2.0%, Mn: 0.6%, Fe: 0.15%, and 0.3 wt.% TiCN refining agent is added, with the balance being Al and unavoidable impurities.

[0019] The specific preparation and die-casting process includes the following steps: First, preliminary preparations are carried out, including a careful inspection of the melting equipment, thorough cleaning of splashed debris in the furnace and residual metal fragments in the crucible to prevent contamination of the alloy liquid by foreign impurities, ensuring accurate alloy composition and stable performance. A multimeter is used to test the power supply and temperature measuring device to ensure accuracy and reliability, eliminate potential leakage hazards, and ensure precise control of process parameters (such as temperature) to improve safety and repeatability. The die-casting mold and pressure chamber runner are preheated to 200℃, and it is confirmed that the mold surface has been evenly sprayed with boron nitride release agent. Preheating the mold avoids thermal stress that could lead to casting defects; even spraying of the release agent ensures a smooth casting surface for easy demolding. The aluminum alloy raw material undergoes surface treatment, carefully grinding it with a sand mill to remove the surface oxide layer and impurities, then wiping it clean with alcohol and thoroughly drying it in a 100℃ oven to completely remove the oxide layer and moisture, reduce gas content and inclusions during the melting process, and improve alloy purity. Some alloy ingots are broken into blocks to accelerate the melting process, increase the melting rate, reduce smelting time, and lower energy consumption. Pure Al, Al-40Si, and Al-10Mn are added to a crucible in the specified ratio and heated to 760℃ to completely melt them. This temperature is maintained for 20 minutes to ensure the full dissolution and initial homogenization of the matrix Al and alloying elements Si and Mn, creating stable conditions for the addition of Mg. When the alloy melt temperature drops to 720℃, pure Mg is added and stirred thoroughly until completely dissolved. After the reaction is complete, the scum on the surface is removed to reduce Mg oxidation loss. Stirring promotes Mg dissolution; removing scum removes oxides and improves alloy quality. Subsequently, TiCN refining agent was added, and an electromagnetic stirring device was activated to homogenize the alloy melt. The stirring frequency was set to 55Hz, the stirring voltage to 380V, and the total stirring time to 600 seconds, including 60 seconds of forward rotation, 60 seconds of reverse rotation, and a 10-second interval. The TiCN refining agent provides nucleation sites, refining the primary phase; electromagnetic stirring enhances melt convection, breaks down temperature and concentration gradients, and achieves homogenization of composition and microstructure. The alternating forward and reverse rotation prevents precipitation and ensures uniform distribution of TiCN particles. Finally, die casting is performed, with the casting temperature strictly controlled at 700℃. During the casting process, operators must take safety precautions, control the injection speed and pressure, and ensure smooth filling. The 700℃ casting temperature optimizes fluidity, and injection control ensures complete mold filling, reducing porosity and shrinkage. After the mold cools naturally, the mold is opened, the casting is removed, and cleaning and post-processing are performed. Natural cooling reduces internal stress; post-processing (such as deburring) improves the appearance and dimensional accuracy of the casting, resulting in a high-performance aluminum-magnesium alloy die casting.

[0020] The aluminum-magnesium alloy obtained in this embodiment has high performance in the as-cast state and does not require heat treatment: tensile strength: ≥330MPa, yield strength: ≥180MPa, elongation: ≥10%.

[0021] Example 3: like Figure 1As shown, this embodiment provides an aluminum-magnesium alloy that is synergistically enhanced by electromagnetic stirring and TiCN refining. By weight percentage, its composition is: Mg: 7.0%, Si: 2.5%, Mn: 0.6%, Fe: 0.15%, with 0.3 wt.% TiCN refining agent added, and the balance being Al and unavoidable impurities.

[0022] The preparation and die-casting method of the aluminum-magnesium alloy includes the following steps: cleaning the smelting equipment and crucible, removing impurities and electrical safety hazards, ensuring a clean and safe smelting environment, preventing the introduction of impurities and electrical faults, and ensuring process stability; preheating the die-casting mold and gating system to 200°C, and spraying boron nitride release agent to reduce the thermal difference between the mold and the alloy liquid, preventing the casting from sticking to the mold or cracking; the release agent improves surface quality; the aluminum alloy raw material undergoes surface polishing, alcohol cleaning, and 100°C drying to remove surface oxides and contaminants, reduce hydrogen content, and prevent porosity and inclusion defects; the crushed alloy ingot is then mixed with pure Al, Al-40Si, Al and 10Mn were added together to the crucible and melted at 760℃ for 20 minutes, with the broken ingots accelerating the melting process. Melting and holding at 760℃ ensured sufficient diffusion and homogenization of the alloying elements. Pure Mg was added when the alloy melt cooled to 720℃. After the reaction, surface slag was removed to reduce the oxidation risk during Mg addition. Slag removal improved alloy purity. TiCN grain refiner was added, and the mixture was stirred for 600 seconds at 55Hz and 380V using an electromagnetic stirrer, alternating between forward and reverse rotation for 60 seconds each, with a 10-second interval. TiCN grain refiner induced heterogeneous nucleation, refining the grains. Electromagnetic stirring enhanced convection, homogenized composition and temperature, and reduced defects. The alternating forward and reverse rotation ensured uniform stirring throughout the mixture. The casting temperature was controlled at 700℃ for die casting, with an injection time of 3 seconds. After cooling, the aluminum-magnesium alloy die casting was obtained. Casting at 700℃ optimized fluidity and filling properties. Controlled injection time ensured molding efficiency. Rapid solidification locked in the microstructure.

[0023] The aluminum-magnesium alloy prepared in this embodiment exhibits excellent comprehensive properties in the as-cast state without the need for heat treatment: tensile strength: ≥340MPa, yield strength: ≥180MPa, elongation: ≥10%.

[0024] like Figure 2 As shown, an example of an electromagnetic stirring device for implementing the method of this application is provided. An openable sealing cover 2 is provided above a graphite inner liner 1. A thermocouple 3 penetrates vertically into the graphite inner liner 1 through the sealing cover 2. The molten alloy 4 is located within the graphite inner liner 1, and the molten alloy 4 can be poured out by opening the cover. The thermocouple 3 is used to detect the temperature of the molten alloy during electromagnetic stirring.

[0025] This embodiment provides a specific method for implementing electromagnetic stirring: An induction coil is wound around the outside or bottom of a furnace (graphite inner liner); the molten metal to be stirred (such as aluminum-magnesium alloy liquid) is placed within the range of the magnetic field, serving as the "object subjected to electromagnetic force"; By supplying ultra-low frequency alternating current to the induction coil through a frequency converter, a magnetic field with periodically changing direction and intensity is formed around the coil (the magnetic field can pass through the furnace wall and act directly on the internal melt without contact). When an induced current is generated in the melt, and an alternating magnetic field passes through the liquid metal, according to Faraday's law of electromagnetic induction, a closed "eddy current" will be induced inside the melt; (the direction of the induced current is opposite to the direction of the magnetic field change, and its magnitude is positively correlated with the magnetic field strength and the conductivity of the melt). In the original alternating magnetic field, the induced current will be subjected to the "Lorentz force" (the force exerted by the magnetic field on the current). The direction of the Lorentz force is perpendicular to the direction of the magnetic field and the current, and is consistent with the "movement direction" of the magnetic field, thereby driving the melt to flow in a fixed direction in a directional and regular manner (such as rotation or horizontal circulation). By adjusting the "output frequency" (which changes the rate of change of the magnetic field, thereby changing the magnitude of the electromagnetic force) and "current intensity" (which changes the magnetic field intensity) of the variable frequency power supply, the stirring speed, direction, and intensity of the melt can be precisely controlled, avoiding melt splashing or gas entrainment caused by excessive stirring.

[0026] The test results of the aluminum-magnesium alloys obtained from Examples 1-3 are summarized in the following table:

[0027] Comparing the test results of Examples 1-3, the following conclusions can be drawn: This application achieves refined grains and a uniform microstructure directly in the as-cast state through the synergistic effect of electromagnetic stirring and TiCN refining agent. TiCN refining agent, acting as a highly efficient heterogeneous nucleation site, and TiCN particles, serving as a highly efficient nucleation substrate, lower the nucleation barrier, increase the nucleation density, and significantly increase the nucleation rate, leading to grain refinement and promoting the formation of fine equiaxed grains. Simultaneously, electromagnetic stirring drives melt flow through electromagnetic force, forcibly convection breaking up dendrite fronts, reducing compositional supercooling, promoting solute redistribution, and facilitating the uniform dispersion of TiCN particles, further refining the grains and eliminating macroscopic segregation. This synergistic process results in a high-density, fine equiaxed grain structure and a uniform second-phase distribution in the as-cast microstructure, equivalent to or even superior to the microstructure after traditional heat treatment. This allows the alloy to form a uniform and fine microstructure during solidification, directly improving strength, toughness, and density. Therefore, high mechanical properties and corrosion resistance can be obtained without heat treatment to adjust the microstructure or eliminate defects, saving energy and time and reducing production costs.

[0028] High performance can be achieved without heat treatment in the as-cast state. All three embodiments do not require traditional aluminum alloy heat treatment, achieving comprehensive performance of "tensile strength ≥320MPa + elongation ≥10%" in the as-cast state. This overcomes the bottleneck of "low strength and poor plasticity" of traditional die-cast alloys (such as ADC12) and avoids problems such as deformation of large parts, high energy consumption, and low yield caused by heat treatment. The composition and process are highly stable and easy to scale up. The Mn, Fe, and TiCN addition amounts and core preparation processes (such as smelting and die-casting parameters) are consistent in all three embodiments. Performance can be stably controlled by adjusting only the Mg and Si ratios, indicating that the composition-process system of this application has strong compatibility with parameter fluctuations, stable element yield, and is suitable for industrial mass production.

[0029] It should be noted that, unless otherwise expressly specified and limited, the term "connection" or its synonyms should be interpreted broadly in this document. For example, "connection" can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. Furthermore, expressions such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. At the same time, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. In addition, the terms "front," "rear," "left," "right," "upper," and "lower" in this document refer to the placement states shown in the accompanying drawings.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for synergistically enhancing the properties of aluminum-magnesium alloy die-castings through electromagnetic stirring and TiCN refining, characterized in that, Includes the following steps: S1. Make preliminary preparations, inspect and clean the smelting equipment, ensure that the power supply and temperature measurement system are normal, and eliminate the risk of leakage. S2. Preheat the die-casting mold and the pressure chamber runner to 200°C, and spray with boron nitride release agent; S3. Perform surface polishing, alcohol cleaning and 100℃ drying on aluminum alloy raw materials; S4. Crush some alloy ingots into blocks, add them to a crucible along with pure Al, Al-40Si, and Al-10Mn, melt them at 760℃ and hold for 20 minutes. S5. When the alloy liquid cools down to 720℃, add pure Mg. After the reaction is complete, remove the slag. S6. Add TiCN refiner and homogenize the alloy liquid using an electromagnetic stirring device; S7. Finally, die casting is performed, with the casting temperature controlled at 700℃ and the injection time at 3 seconds. After the mold cools, the aluminum-magnesium alloy casting is removed.

2. The method for synergistically enhancing the performance of aluminum-magnesium alloy die castings by electromagnetic stirring and TiCN refinement according to claim 1, wherein the weight percentage of each component of the aluminum-magnesium alloy is: Mg: 6.5%–7.0%, Si: 2.0%–2.5%, Mn: 0.6%, Fe: 0.15%, TiCN: 0.3wt.%, with the balance being Al.

3. The method for synergistically enhancing the properties of aluminum-magnesium alloy die-castings by electromagnetic stirring and TiCN refinement according to claim 1 or 2, characterized in that: The die-casting mold and sprue need to be preheated to above 200°C, and boron nitride release agent should be evenly applied to the surface of the mold.

4. The method for synergistically enhancing the properties of aluminum-magnesium alloy die-castings by electromagnetic stirring and TiCN refinement according to claim 1 or 2, characterized in that: The aluminum alloy raw material must be polished by a sand mill to remove the oxide layer, cleaned with alcohol, and then dried in an oven at 100°C.

5. The method for synergistically enhancing the properties of aluminum-magnesium alloy die-castings by electromagnetic stirring and TiCN refinement according to claim 1 or 2, characterized in that: The die-casting temperature is controlled at 700–720℃.

6. The method for synergistically enhancing the properties of aluminum-magnesium alloy die-castings by electromagnetic stirring and TiCN refinement according to claim 1 or 2, characterized in that: The die-casting process uses a pressurization mode, with an injection time of 3 seconds.

7. The method for synergistically enhancing the properties of aluminum-magnesium alloy die-castings by electromagnetic stirring and TiCN refinement according to claim 1 or 2, characterized in that: The parameters of the electromagnetic stirring device are set as follows: stirring frequency 5–50Hz, stirring voltage 0–380V, and stirring time 600 seconds.

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