Accurate regulation and control method and system for chemical components of TC4 return scrap EB + VAR duplex smelting cast ingot

Abstract

The invention discloses an accurate regulation and control method and system for chemical components of TC4 return scrap EB + VAR duplex smelting cast ingots, belongs to the technical field of titanium alloy precision metallurgy, and constructs a set of intelligent closed-loop process system. The method comprises the core steps that firstly, the temperature of a molten pool is calculated on line based on EB furnace heat balance and serves as core input, and a model is established according to the Langmuir law to predict the volatilization rate of the Al element in real time; secondly, the Al compensation amount is dynamically calculated according to the prediction result, meanwhile, the feeding process is stabilized by optimizing the charging density and stabilizing the feeding process of the return scrap and the compensation aluminum material in a blank pressing or laminating mode, the fluctuation of the smelting speed is controlled within + / -5%, and an EB cast ingot with preliminarily uniform components is prepared; and finally, the EB cast ingot is subjected to VAR remelting, and ultimate homogenization is achieved through the electromagnetic stirring and directional solidification effects of the EB cast ingot. According to the cast ingot obtained through the method, the deviation of the total-length Al element content is stably controlled within + / -0.4%, and the component uniformity, the batch stability and the return scrap utilization rate are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of precision metallurgy technology for titanium alloys, specifically to a method and system for precise control of the chemical composition of TC4 return material EB+VAR duplex melting ingots. Background Technology

[0002] As a key material for aero-engines and fuselage structural components, the recycling of the large amount of recycled materials (such as scrap, forging flash, and machining chips) generated during the production of TC4 titanium alloy is of significant economic and strategic importance for reducing production costs and achieving green manufacturing. The dual-process smelting of electron beam cold hearth furnace (EB) and vacuum arc remelting furnace (VAR) is currently the mainstream process for processing such recycled materials to remove high- and low-density inclusions and obtain high-quality ingots.

[0003] However, this process faces a prominent and unresolved core technical challenge when handling return materials with diverse physical forms and large specific surface areas, especially cutting chips: the uneven density and shape of the return materials easily lead to unstable feeding speeds in the feeding system, causing fluctuations in the EB furnace melting process. Changes in the molten pool temperature directly affect the volatilization rate of volatile elements such as Al, ultimately resulting in uneven chemical composition of the ingot, especially severe vertical segregation of Al, making it difficult to meet the stringent requirements for compositional uniformity in aerospace-grade materials (typically requiring an Al content deviation of ≤±0.4%). Currently, industrial practice relies heavily on fixed compositional compensation coefficients and operator experience for post-processing analysis and inter-furnace adjustments. This control strategy has significant lag, failing to perceive and respond to dynamic changes during a single melting process in real time. This results in low compositional qualification rates and poor batch stability of return material ingots, severely restricting the high-proportion, safe, and reliable application of return materials in high-end titanium alloy components.

[0004] To address the aforementioned challenges, existing technologies have explored various approaches, but all have certain limitations. For example, Chinese invention patent CN120989430A discloses a short-process recycling smelting method for TC4 titanium alloy scrap in an EB furnace. The core of this method is to prepare scrap of a specific size, aluminum briquettes, and functional agents, mix and press them into a billet, and then smelt them, employing a segmented temperature control strategy. It compensates for aluminum volatilization losses during the smelting process by adding core-shell aluminum briquettes and uses functional agents to control oxygen content. This technical solution achieves control over the content of the target element to a certain extent, but its compensation mechanism is essentially static and preset. That is, the amount of aluminum briquettes added is determined in advance based on experience or a fixed ratio, failing to form a closed-loop feedback and dynamic linkage with the real-time changing state of the molten pool during the smelting process. Therefore, it is still difficult to completely solve the problem of instantaneous changes in Al element recovery rate and final segregation caused by real-time disturbances such as feeding fluctuations.

[0005] On the other hand, in the broader field of intelligent control of metallurgical processes, some technologies attempt to introduce data-driven models to achieve more precise regulation. For example, Chinese invention patent CN117577217A discloses a method for optimizing the chemical composition and precisely controlling the smelting of a new type of wear-resistant steel. This method collects production data and uses a BP neural network to establish a preset model for optimizing the chemical composition and a prediction model for precise control of special element smelting, aiming to optimize and predict alloy proportions. This technology represents progress from empirical methods to model prediction methods, but its technical background and application are in the steel smelting process, which is fundamentally different from the high-temperature melting process of titanium alloys in a high-vacuum EB furnace. Therefore, it cannot be applied to or solve the problems existing in this invention.

[0006] In summary, existing technologies either employ static, open-loop compensation strategies in the titanium alloy field, failing to achieve dynamic process response; or introduce intelligent models in other metallurgical fields, but these cannot be directly applied to the specific scenarios of titanium alloy EB melting. Therefore, there is an urgent need in this field to develop a new method and technology system that can deeply integrate the physicochemical mechanisms of the titanium alloy EB melting process, respond to process fluctuations in real time, and achieve dynamic and precise closed-loop control of volatile elements such as Al. Summary of the Invention

[0007] The purpose of this invention is to provide a method and system for precise control of the chemical composition of TC4 return material EB+VAR duplex melting ingots, so as to achieve precise and repeatable control of the chemical composition of TC4 titanium alloy return material EB+VAR duplex melting ingots, especially the uniformity of Al element.

[0008] The technical solution of this invention is a method for precise control of the chemical composition of TC4 return material EB+VAR dual-melting ingots. This method constructs an intelligent closed-loop process system encompassing online calculation of molten pool temperature, real-time prediction of element volatilization, dynamic determination of compensation amount, stable control of the feeding process, and ultimate homogenization via VAR. The system includes the following steps: Step S1: Calculation of molten pool surface temperature and prediction of volatilization. Based on the heat balance principle during EB furnace operation, the surface temperature of the EB furnace molten pool is calculated online. And based on the calculated surface temperature of the molten pool Using Langmuir's law as the key input parameter, the real-time volatilization rate of Al is predicted. ; Step S2: Precise compensation and stable feeding. Based on the real-time prediction of the Al volatilization rate in step S1, the compensation amount of Al is dynamically calculated and determined for precise compensation. At the same time, a self-consuming silo is used and the feeding density is controlled to ensure stable feeding, so that the feeding speed matches the melting power and the fluctuation of the feeding speed and melting speed are controlled within ±5%, so as to prepare EB ingots with initially uniform composition. Step S3: VAR furnace remelting and homogenization. The EB ingot obtained in step S2 is remelted in a VAR furnace. By using electromagnetic stirring and directional solidification, the uniformity of Al content in the final TC4 return ingot is stabilized to a level where the deviation does not exceed ±0.4% throughout its entire length.

[0009] Furthermore, in step S1, the surface temperature of the molten pool is calculated based on the heat balance principle of the EB furnace. Specifically, this involves establishing and solving the following energy balance equations: in: P – Electron beam input power Qm – Heat required to melt the raw material Qt – Heat loss due to conduction ε – Emissivity of the molten pool surface σ – Stefan-Boltzmann constant - The radiation area of ​​the molten pool.

[0010] Furthermore, the heat required for melting the raw material, Qm, is calculated using the following formula: Qm= in: V - Melting speed - Specific heat capacity at constant pressure of the raw material, - The temperature change of the raw material from its initial temperature to its melting point. - Latent heat of fusion of raw materials Conductive heat loss is calculated using the following formula: = in: - Heat transfer area - Thermal conductivity of the material - The temperature change of the raw material from its initial temperature to its melting point Furthermore, based on Langmuir's law, the following elemental volatilization kinetic model is established to accurately predict the real-time volatilization rate of Al. The volatilization kinetics model is as follows: in, - Activity of Al in TC4 alloy - Saturated vapor pressure of Al - Molar mass of Al R – Ideal gas constant -constant.

[0011] Further, in step S2, the compensation amount of Al is dynamically calculated and determined based on the predicted Al volatilization rate. Specifically, the volatilization amounts of Al and Ti during the EB furnace smelting process, i.e., the compensation amounts of Al and Ti, are calculated using the following formula: in, - Volatilization of Al and Ti - Volatilization rates of Al and Ti - Volatile area - Evaporation time The evaporation area includes the cooling bed area, crucible area, and gating area, and the evaporation time is the melt residence time; The required compensation for the weight of Al element is calculated using the following formula: In the formula, - Weight of TC4 alloy return material (kg) - Al content in TC4 alloy return material y%-EB furnace TC4 alloy ingot Al element content - Amount of Al volatilized during the smelting process (kg) - Ti volatilization during the smelting process (kg) - The weight (kg) of Al element needs to be compensated.

[0012] Furthermore, the control of the loading density in step S2 is specifically as follows: for shaving return material, it is uniformly mixed with compensating aluminum granules and then pressed into a high-density billet; for block return material, the compensating aluminum plate and the return material are regularly stacked in a cross-layering manner.

[0013] Furthermore, in step S3, the process parameters for VAR furnace remelting satisfy the following: the vacuum degree is controlled within the range of 0.3~0.7 Pa, and a multi-stage feeding process is adopted.

[0014] Furthermore, the Al content in the head, middle, and tail sections of the prepared TC4 return ingot varies by no more than 0.8%.

[0015] A precise control system for smelting composition includes: an EB furnace and a VAR furnace connected in sequence, a consumable hopper located at the feed end of the EB furnace, and a central controller electrically connected to the consumable hopper and the EB furnace.

[0016] Furthermore, the central controller is configured to store and run the heat balance calculation model and the element volatilization prediction model, and adjust the feeding speed of the self-consuming silo and the melting power of the EB furnace in real time according to the model calculation results.

[0017] The beneficial effects of this invention are: 1. The compositional uniformity of the ingot prepared by this invention is improved: by constructing an intelligent closed-loop control system with online calculation of molten pool temperature and real-time prediction of Al volatilization as the core, dynamic and accurate compensation for volatilization loss is achieved from the source. Furthermore, by utilizing the ultimate homogenization effect of VAR remelting, the Al content deviation of the final ingot along its entire axial length can be stably controlled within ±0.4%, with a range ≤0.8%. The product meets the stringent requirements for compositional uniformity of aerospace-grade materials.

[0018] 2. This invention offers high control precision and good repeatability: It abandons the traditional post-adjustment mode that relies on fixed compensation coefficients and operational experience, and adopts a quantitative control method based on physical models, which significantly reduces the uncertainty of human experience and greatly improves the accuracy of process control and the stability between different production batches.

[0019] 3. The invention exhibits strong process adaptability: By optimizing the charging density to address the core issue of unstable feeding caused by return materials in different physical forms, the feeding speed of the consumable silo is ensured to be stable, thereby controlling the melting speed fluctuation within ±5%. This effectively suppresses abnormal thermal states of the molten pool caused by feeding fluctuations, enabling the method to reliably handle return materials in various forms and broadening the range of qualified raw material sources.

[0020] 4. This method offers significant economic benefits: TC4 titanium alloy recycled materials constitute a high proportion of aerospace-grade products, providing a reliable technical path for their safe application. By achieving precise and stable control of composition and a high yield rate, the recycling rate of recycled materials can be significantly improved, directly reducing dependence on expensive virgin materials such as sponge titanium, thereby generating significant economic benefits and aligning with the goals of green manufacturing and sustainable development. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart illustrating the process for precise control of the chemical composition of the ingots according to the present invention. Figure 2 The EB furnace charging box uses TC4 titanium alloy block return material as the charging method. Figure 3 This is a schematic diagram of the Al content distribution in the head, middle, and tail sections of the EB ingot in Example 1; Figure 4 This is a schematic diagram of the Al content distribution in the head, middle, and tail sections of the VAR ingot in Example 1; Figure 5 This is a schematic diagram of the melting temperature and volatilization rate distribution in Example 1; Figure 6 The EB furnace charging box uses TC4 titanium alloy scrap return material as the charging method. Figure 7 is a schematic diagram of the melting rate and AI element content distribution in Example 2; Figure 8 This is a schematic diagram of the Al content distribution in the head, middle, and tail sections of the EB ingot in Example 2; Figure 9 This is a schematic diagram of the Al content distribution in the head, middle, and tail sections of the VAR ingot in Example 2. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and conventional means in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0024] The method of this invention is based on a precise control system for smelting composition. The control system includes an EB furnace and a VAR furnace connected in sequence, a consumable hopper located at the feed end of the EB furnace, and a central controller electrically connected to the consumable hopper and the EB furnace. The central controller is configured to store and run a heat balance calculation model and an element volatilization prediction model, and to adjust the feeding speed of the consumable hopper and the smelting power of the EB furnace in real time according to the model calculation results.

[0025] Reference Figure 1This invention discloses a method for precise control of TC4 recycled material EB+VAR composition based on thermal balance and volatilization prediction. Its core lies in constructing an intelligent closed-loop process system that includes "calculating the molten pool temperature based on thermal balance → predicting element volatilization → precise compensation → stabilizing the feeding power → VAR final homogenization." Specifically, it includes the following steps: Step S1: Online calculation of molten pool temperature and prediction of element volatilization Based on the thermal balance principle of the EB furnace, an energy balance equation is established and solved to calculate the surface temperature T of the molten pool in the EB furnace. The energy balance equation is as follows: Where P is the electron beam input power, Qm is the heat required to melt the raw material, ε is the emissivity of the molten pool surface, σ is the Stefan-Boltzmann constant, S is the radiating area, Tl represents the molten pool surface temperature to be determined, Qt is the conductive heat loss, and V is the melting rate. The surface radiation area of ​​the molten pool. The specific heat capacity at constant pressure of the raw material is given by - The temperature change of the raw material from its initial temperature to its melting point. The latent heat of fusion of the raw material, For heat transfer area, The heat transfer coefficient of the material, It represents the temperature change of the raw material from its initial temperature to its melting point.

[0026] Based on Langmuir's law, and using the calculated molten pool temperature Tl as the core input parameter, an element volatilization kinetic model is established to accurately predict the real-time volatilization rate VAl of Al. The volatilization kinetic model is as follows: in, The activity of Al in TC4 alloy. The saturated vapor pressure of Al. Let be the molar mass of Al, and R be the ideal gas constant.

[0027] Step S2: Precise element compensation and stable control of the feeding process Based on the Al volatilization rate predicted in step S1 This process accurately calculates and determines the required Al element compensation, achieving a leap from "empirical estimation" to "model-based quantification." Simultaneously, to achieve a stable match between feeding speed and melting power, a self-consumable silo system is employed, and the stability of the feeding process is ensured by controlling the charging density. (Refer to...) Figure 3The specific material stacking method is as follows: for shaving-like return material, it is uniformly mixed with compensating aluminum briquettes and then pressed into high-density billets; for block-like return material, an optimized material distribution method is adopted, which involves layering and regularly stacking it with aluminum plates. Through the above measures, the fluctuations in the actual feeding speed and melting speed are controlled within ±5% of the preset values, thereby stabilizing the heat input of the molten pool, suppressing abnormal fluctuations in element volatilization, and producing EB ingots with initially uniform composition.

[0028] The compensation amount for the Al element is obtained from: , The amount of Al and Ti volatilized. The evaporation rate of Al element, For evaporation area, The volatilization time is the time the melt remains in the melt. The volatilization area includes the cooling bed area, crucible area, and gating area. Ti will also volatilize during the smelting process, and the compensation method for Ti is the same as that for Al.

[0029] The required compensation for the weight of Al element is calculated using the following formula: The weight (kg) of the TC4 alloy return material. y% represents the Al content of the returned TC4 alloy material, and y% represents the Al content of the TC4 alloy ingot cast from the EB furnace. This represents the amount of Al volatilized during the smelting process (kg). This represents the amount of Ti volatilized during the smelting process (kg).

[0030] Step S3, VAR remelting and final homogenization The EB ingot obtained in step S2 was used as an electrode and remelted in a VAR furnace. By precisely controlling the melting current and vacuum level of the VAR furnace within the range of 0.3~0.7 Pa, and employing a multi-stage feeding process, the composition of the ingot was ultimately homogenized by utilizing the strong electromagnetic stirring and directional solidification effect of the VAR process. Ultimately, the uniformity of the Al element chemical composition of the TC4 return ingot was stably controlled within ±0.4% (i.e., range ≤0.8%) over the entire length, meeting aerospace standards.

[0031] Example 1: Recycling 100% TC4 titanium alloy block recycled material Step 1: Raw material preparation: Collect 600kg of TC4 blocks and pre-treat them by strict cleaning and drying.

[0032] Step 2: EB furnace smelting and closed-loop control Step 21: Based on the model, the required aluminum plate compensation is calculated to be 9.88 kg. Specifically, the Al volatilization rate is obtained. Then prepare aluminum plates, each measuring 1463×1.5×336mm, in a quantity of 5. These plates are arranged in a cross-layered manner and loaded into a consumable hopper. Note that the aluminum plates should be placed under the titanium alloy return material to prevent the electron gun from directly attacking the aluminum plates.

[0033] Step 22: In the BMO-25 EB furnace, the central controller runs the heat balance model and volatilization prediction model in real time. The melting speed is set to 200 kg / h, and the molten pool temperature is set to 1790℃ (2063 K). When the system detects fluctuations in the melting speed or deviations in the molten pool temperature from the set values, it immediately adjusts the feeding speed and electron beam power to stabilize the melting speed at 200 ± 5 kg / h and control the molten pool temperature fluctuation within ± 20 K. Figure 5 .

[0034] Step 23: Melting completes, yielding EB ingots. (Refer to...) Figure 3 Tests showed that the Al content was 6.44% in the head, 6.58% in the middle, and 6.10% in the tail, with a range of 0.48% between the head, middle, and tail.

[0035] Step 3: VAR furnace remelting. The EB ingot is remelted in a 3t VAR furnace with a vacuum degree of 0.5Pa and a multi-stage feeding process.

[0036] Step 4: Final inspection, refer to Figure 4 The sampling analysis of the final VAR ingot showed that the Al content was 6.12% in the head, 6.36% in the middle, and 6.43% in the tail, with a range of 0.31%, which fully met the uniformity requirement of ±0.4%, and the content of all elements complied with the GB / T3620.1-2016 standard.

[0037] Example 2: Recycling TC4 titanium alloy scrap Step 1: Raw material preparation and compaction: The raw materials are prepared based on "30% TC4 scrap recycled material + 70% new material (sponge titanium, etc.)" to obtain 603 kg of raw materials; Step 2: EB furnace smelting and closed-loop control: Step 21: Based on the model calculation, the required aluminum compensation is 9.88 kg. Weigh the aluminum briquettes, sponge titanium, aluminum-vanadium master alloy, titanium dioxide, and TC4 scrap as described above, totaling 603 kg. After mixing, press the mixture into 9 billets using an 8000-ton press: 8 billets (numbered A) each weigh 64.625 kg, with dimensions of 600×320×130 mm and a density of approximately 2.589 g / cm³; the remaining billet (numbered B) weighs 86.4 kg, with dimensions of 600×320×180 mm and a density of approximately 2.50 g / cm³. The amount of aluminum briquettes added to billet B (3.36 kg) is slightly higher than that to billet A (2.49 kg / bill). Billet B is placed at the front of the charging mechanism to compensate for additional aluminum volatilization caused by unstable vacuum and current during the initial melting stage. Load the 9 pressed billets into the consumable hopper in sequence, ensuring that billet B is at the front, referring to... Figure 6 .

[0038] Step 22: In the BMO-25 EB furnace, the central controller runs the heat balance and volatilization prediction model in real time. The target melting speed and molten pool temperature are set. When the system detects parameter fluctuations, it immediately and collaboratively adjusts the feeding speed and electron beam power to strictly control the melting speed and molten pool temperature fluctuations within the set range, referring to... Figure 7 . Step 23: Melting completes, yielding EB ingots. Sampling and analysis of the ingots show the Al content as follows: 5.630% at the head, 5.598% in the middle, and 5.481%, 5.102%, and 5.561% at the tail (150mm, 100mm, and 50mm) respectively, with a range of 0.069%. (Refer to...) Figure 8 .

[0039] Step 3: VAR furnace remelting: Using the above EB ingot as an electrode, remelting is carried out in a 3t VAR furnace, controlling the appropriate vacuum degree and adopting a multi-stage feeding process.

[0040] Step 4: Final Inspection: Samples are taken from the final ingot after VAR remelting for analysis, referring to... Figure 9 The test results showed that the average Al content at the head (50mm) was 5.90%, the middle was 5.90%, and the tail (50mm) was 6.04%, with a range of 0.14% between the head, middle, and tail. This fully meets the ±0.4% uniformity requirement, demonstrating excellent chemical composition uniformity across the entire length of the ingot, with all element contents conforming to the requirements of GB / T3620.1-2016 standard.

[0041] The above provides a detailed description of the method and system for precise control of the chemical composition of TC4 return material EB+VAR duplex melting ingots provided by this invention. Specific examples have been used to illustrate the structure and working principle of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the scope of protection of the claims of this invention.

Claims

1. A method for precise control of the chemical composition of TC4 return material EB+VAR duplex melting ingots, characterized in that: The construction of an intelligent closed-loop process system includes the following steps: online calculation of molten pool surface temperature, real-time prediction of element volatilization, dynamic determination of compensation amount, stable control of the feeding process, and ultimate homogenization via VAR. Step S1: Calculation of molten pool surface temperature and prediction of volatilization. Based on the heat balance principle during EB furnace operation, the surface temperature of the EB furnace molten pool is calculated online. And based on the calculated surface temperature of the molten pool Using Langmuir's law as the key input parameter, the real-time volatilization rate of Al is predicted. ; Step S2: Precise compensation and stable feeding. Based on the real-time prediction of the Al volatilization rate in step S1, the compensation amount of Al is dynamically calculated and determined for precise compensation. At the same time, a self-consuming silo is used and the feeding density is controlled to ensure stable feeding, so that the feeding speed matches the melting power and the fluctuation of the feeding speed and melting speed are controlled within ±5%, so as to prepare EB ingots with initially uniform composition. Step S3: VAR furnace remelting and homogenization. The EB ingot obtained in step S2 is remelted in a VAR furnace. By using electromagnetic stirring and directional solidification, the uniformity of Al content in the final TC4 return ingot is stabilized to a level where the deviation does not exceed ±0.4% throughout its entire length.

2. The method for precise control of the chemical composition of TC4 return material EB+VAR duplex melting ingots according to claim 1, characterized in that: In step S1, the surface temperature of the molten pool is calculated based on the heat balance principle of the EB furnace. Specifically, this involves establishing and solving the following energy balance equations: in: P – Electron beam input power Qm – Heat required to melt the raw material Qt – Heat loss due to conduction ε – Emissivity of the molten pool surface σ – Stefan-Boltzmann constant - Surface radiation area of ​​the molten pool.

3. The method for precise control of the chemical composition of TC4 return material EB+VAR duplex melting ingots according to claim 2, characterized in that: The heat required for melting the raw material, Qm, is calculated using the following formula: Qm= in: V - Melting speed - Specific heat capacity at constant pressure of the raw material, - The temperature change of the raw material from its initial temperature to its melting point. - Latent heat of fusion of raw materials Conductive heat loss is calculated using the following formula: = in: - Heat transfer area - The heat transfer coefficient of the material - The temperature change of the raw material from its initial temperature to its melting point.

4. The method for precise control of the chemical composition of TC4 return material EB+VAR duplex melting ingots according to claim 1, characterized in that: Based on Langmuir's law, the following elemental volatilization kinetic model is established to accurately predict the real-time volatilization rate of Al. The volatilization kinetics model is as follows: in, - Activity of Al in TC4 alloy - Saturated vapor pressure of Al - Molar mass of Al R – Ideal gas constant -constant.

5. The method for precise control of the chemical composition of TC4 return material EB+VAR duplex melting ingots according to claim 1, characterized in that: In step S2, the compensation amount of Al is dynamically calculated and determined based on the predicted Al volatilization rate. Specifically, the volatilization amounts of Al and Ti during the EB furnace smelting process, i.e., the compensation amounts of Al and Ti, are calculated using the following formula: in, - Volatilization of Al and Ti - Volatilization rates of Al and Ti - Volatile area - Evaporation time The evaporation area includes the cooling bed area, crucible area, and gating area, and the evaporation time is the melt residence time; The required compensation for the weight of Al element is calculated using the following formula: In the formula, - Weight of TC4 alloy return material (kg) - Al content in TC4 alloy return material y%-EB furnace TC4 alloy ingot Al element content - Amount of Al volatilized during the smelting process (kg) - Ti volatilization during the smelting process (kg) - The weight (kg) of Al element needs to be compensated.

6. The method for precise control of the chemical composition of TC4 return material EB+VAR duplex melting ingots according to claim 1, characterized in that: The control of the loading density in step S2 is specifically as follows: for shaving return material, it is mixed evenly with compensating aluminum granules and then pressed into a high-density billet; for block return material, the compensating aluminum plate and the return material are stacked regularly in a cross-layering manner.

7. The method for precise control of the chemical composition of TC4 return material EB+VAR duplex melting ingots according to claim 1, characterized in that: In step S3, the process parameters for VAR furnace remelting are: the vacuum degree is controlled within the range of 0.3~0.7 Pa, and a multi-stage feeding process is adopted.

8. The method for precise control of the chemical composition of TC4 return material EB+VAR duplex melting ingots according to claim 1, characterized in that: The Al content in the head, middle and tail sections of the prepared TC4 return ingot varies by no more than 0.8%.

9. A system for precisely controlling the smelting composition for implementing the method of any one of claims 1-8, characterized in that, include: The EB furnace and VAR furnace are connected in sequence, a consumable hopper is set at the feed end of the EB furnace, and a central controller is electrically connected to the consumable hopper and the EB furnace.

10. The precise control system for smelting composition according to claim 9, characterized in that: The central controller is configured to store and run the heat balance calculation model and the element volatilization prediction model, and adjust the feeding speed of the self-consuming silo and the melting power of the EB furnace in real time according to the model calculation results.

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