Semi-solid thixoforming method and system for spray-formed aluminum alloy blank

Abstract

The invention provides a semi-solid thixoforming method and system for a spray-formed aluminum alloy blank, and is applied to the technical field of aluminum alloy machining. The method comprises the following steps: heating a spray-molded aluminum alloy blank to a semi-solid temperature zone, so that the internal liquid phase fraction of the spray-molded aluminum alloy blank reaches 30-70%, and forming semi-solid slurry formed by coating solid-phase spherical particles with a uniform liquid film; placing the semi-solid slurry in a lower die of a forming die, and controlling an upper die of the forming die to press downwards by adopting a segmented pressure control process, so that the semi-solid slurry completes defect repair and forming in a closed cavity, and a deformed aluminum alloy forge piece is obtained; and the deformed aluminum alloy forge piece is cooled and solidified, and the target aluminum alloy forge piece is obtained. According to the method, precise forming of the aluminum alloy forge piece and synchronous elimination of microstructure defects are effectively completed, and the density, the mechanical property and the forming precision of the aluminum alloy forge piece are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of aluminum alloy processing technology, and in particular to a semi-solid thixotropic forming method and system for spray-formed aluminum alloy billets. Background Technology

[0002] Spray forming technology, with its advantages of rapid cooling, fine and uniform microstructure, and minimal segregation of alloying elements, has become an important process for manufacturing high-performance, high-alloy aluminum alloys (such as the 7xxx series of ultra-high-strength aluminum alloys). However, due to the inherent characteristics of the spray forming process, the preform often inevitably contains a certain proportion of defects such as micropores, porosity, and incomplete fusion between layers. These micro-defects not only reduce the density of the material but also become stress concentration sources when the part is under stress, severely weakening the material's mechanical properties and fatigue life.

[0003] However, how to achieve precision forming of high-performance parts is a technical problem that urgently needs to be solved in the field of high-performance aluminum alloy processing. Summary of the Invention

[0004] This application provides a semi-solid thixotropic forming method for spray-formed aluminum alloy billets to solve the defects in precision forming of high-performance parts in the prior art, realize the simultaneous processing of macro-precision forming and micro-structural defect elimination, and improve the density and mechanical properties of aluminum alloy forgings.

[0005] This application provides a semi-solid thixotropic forming method for spray-formed aluminum alloy billets, including: The spray-formed aluminum alloy billet is heated to the semi-solid temperature zone, so that the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 30% to 70%, forming a semi-solid slurry composed of solid phase spherical particles coated with a uniform liquid film. The semi-solid slurry is placed in the lower mold of the forming mold, and the upper mold of the forming mold is pressed down using a segmented pressure control process, so that the semi-solid slurry completes defect repair and forming in the closed cavity to obtain the deformed aluminum alloy forging. The deformed aluminum alloy forging is cooled and solidified to obtain the target aluminum alloy forging.

[0006] A semi-solid thixotropic forming method for spray-formed aluminum alloy billets according to an embodiment of this application, wherein a segmented pressure control process is used to control the downward pressing of the upper die of the forming mold, so that the semi-solid slurry completes defect repair and forming within a closed cavity to obtain a deformed aluminum alloy forging, comprising: using a first pressure in a first pressure segment to control the downward pressing of the upper die of the forming mold; utilizing the superplastic flow characteristics of the liquid phase in the semi-solid slurry to remove internal gas from the semi-solid slurry, thereby obtaining a prototype of the target aluminum alloy forging; and using... Using the second pressure in the second pressure section, the upper die of the forming mold is controlled to continue pressing down. The capillary effect drives the liquid phase in the semi-solid slurry to penetrate into the micropores inside the semi-solid slurry, completing the filling and repair of porosity and interlayer non-fusion defects in the prototype of the target aluminum alloy forging, and obtaining the repaired part of the target aluminum alloy forging. Using the third pressure in the third pressure section, the upper die of the forming mold is controlled to continue pressing down. By forcibly plastically deforming the repaired part of the target aluminum alloy forging, the deformed aluminum alloy forging is obtained.

[0007] A semi-solid thixotropic forming method for spray-formed aluminum alloy billets according to an embodiment of this application, wherein the spray-formed aluminum alloy billet is heated to a semi-solid temperature range, so that the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 30% to 70%, forming a semi-solid slurry composed of solid-phase spherical particles coated with a uniform liquid film, includes: in a first stage, rapidly heating the spray-formed aluminum alloy billet from room temperature to 50°C below the solidus temperature at a heating rate of ≥10°C / s to obtain a first aluminum alloy billet; in a second stage, heating the first aluminum alloy billet to the solidus temperature and holding it at that temperature, so that the temperature difference between the center and the surface of the first aluminum alloy billet is ≤10°C, to obtain a second aluminum alloy billet; in a third stage, heating the second aluminum alloy billet from the solidus temperature to a target semi-solid temperature within the semi-solid temperature range to obtain the semi-solid slurry, wherein the target semi-solid temperature corresponds to a liquid phase fraction of 30% to 70%.

[0008] According to an embodiment of this application, a semi-solid thixotropic forming method for spray-formed aluminum alloy billets is provided. The pressure in the first pressure section is 20% to 49% of the rated total pressure. Under the action of the first pressure, the semi-solid slurry undergoes grain boundary sliding and rotation, and initially fills the deep ribs and narrow grooves of the forming mold.

[0009] According to an embodiment of this application, a semi-solid thixotropic forming method for spray-formed aluminum alloy billets is provided. The pressure in the second pressure section is 50% to 79% of the rated total pressure, and the holding time is 3 to 10 seconds. The pressure gradient established by the second pressure is used to coordinate with the capillary pressure generated by the surface tension of the liquid phase in the semi-solid slurry, guiding the liquid phase in the semi-solid slurry to converge towards the micron-level loose and interlayer unfused defects and to undergo metallurgical bonding.

[0010] According to an embodiment of this application, a semi-solid thixotropic forming method for spray-formed aluminum alloy billets is provided, wherein the pressure in the third pressure section is 80% to 100% of the rated total pressure, and is used to force plastic deformation of the repair part of the target aluminum alloy forging.

[0011] According to an embodiment of this application, a semi-solid thixotropic forming method for spray-formed aluminum alloy billets is provided. During the segmented pressure control process, the downward pressing speed of the upper die of the forming mold is controlled by a variable speed. The variable speed control includes: in the first pressure segment, controlling the upper die of the forming mold to press down at a first speed, so that the semi-solid slurry is in a superplastic flow state; in the second pressure segment, controlling the upper die of the forming mold to press down at a second speed, the second speed being less than the first speed, and increasing the holding time, so as to utilize the capillary effect to allow the liquid phase in the semi-solid slurry to fully penetrate into the porous and interlayer unfused defects in the prototype of the target aluminum alloy forging.

[0012] A semi-solid thixotropic forming method for spray-formed aluminum alloy billets, according to an embodiment of this application, involves cooling and solidifying the deformed aluminum alloy forging to obtain a target aluminum alloy forging when the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 50% to 65%. The method includes: cooling the deformed aluminum alloy forging to obtain a third aluminum alloy billet; reheating the third aluminum alloy billet to a preset solid phase temperature range to obtain a fourth aluminum alloy billet; placing the fourth aluminum alloy billet in the lower die of a target forging mold and controlling the upper die of the target forging mold to press down to obtain the target aluminum alloy forging, wherein the shape of the target aluminum alloy forging matches the target forging mold.

[0013] According to an embodiment of this application, a semi-solid thixotropic forming method for spray-formed aluminum alloy blanks is provided. The method further includes: before entering the third pressure section, according to the displacement of the upper mold of the forming mold or a set time threshold, cyclically using the pressure in the first pressure section and the pressure in the second pressure section to control the upper mold of the forming mold to continue pressing down, so that the semi-solid slurry completes defect repair in the closed cavity.

[0014] According to an embodiment of this application, a semi-solid thixotropic forming method for spray-formed aluminum alloy billets is provided. The step of cooling and solidifying the deformed aluminum alloy forging to obtain a target aluminum alloy forging includes: maintaining the pressure of the upper die of the forming die in the third pressure segment while keeping the forming die in a closed state, and cooling the deformed aluminum alloy forging after a preset time to obtain the target aluminum alloy forging.

[0015] This application also provides a semi-solid thixoforming system for spray-formed aluminum alloy billets, including: The heating module is used to heat the spray-formed aluminum alloy billet to the semi-solid temperature zone, so that the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 30% to 70%, forming a semi-solid slurry composed of solid phase spherical particles coated with a uniform liquid film.

[0016] The pressing and deformation module is used to place the semi-solid slurry in the lower mold of the forming mold, and to control the upper mold of the forming mold to press down using a segmented pressure control process, so that the semi-solid slurry completes defect repair and forming in the closed cavity, and obtains the deformed aluminum alloy forging.

[0017] The target deformation module is used to cool and solidify the deformed aluminum alloy forging to obtain the target aluminum alloy forging.

[0018] This application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the semi-solid thixotropic forming method for spray-formed aluminum alloy billets as described above.

[0019] This application also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the semi-solid thixotropic forming method for spray-formed aluminum alloy billets as described above.

[0020] This application also provides a computer program product, including a computer program that, when executed by a processor, implements a semi-solid thixotropic forming method for spray-formed aluminum alloy billets as described above.

[0021] The semi-solid thixotropic forming method for spray-formed aluminum alloy billets provided in this application involves heating the spray-formed aluminum alloy billet to a semi-solid temperature range, causing the internal liquid phase fraction of the spray-formed aluminum alloy billet to reach 30% to 70%, forming a semi-solid slurry composed of solid-phase spherical particles coated with a uniform liquid film; placing the semi-solid slurry in the lower mold of a forming mold, and using a segmented pressure control process to control the downward pressure of the upper mold of the forming mold, so that the semi-solid slurry completes defect repair and forming within a closed cavity, obtaining a deformed aluminum alloy forging; and cooling and solidifying the deformed aluminum alloy forging to obtain the target aluminum alloy forging. A three-stage gradient heating process is used to precisely transform spray-formed aluminum alloy billets into semi-solid slurries consisting of solid particles coated with liquid film. The core of the process is segmented pressure and variable speed control. During the forming process, the superplastic flow of the liquid phase is used to remove gas, and the capillary effect is used to drive the liquid phase to penetrate into the micropores to repair porosity and interlayer non-fusion defects. Finally, high-pressure forced plastic deformation is used to achieve densification. Thus, the precision forming of complex aluminum alloy forgings and the simultaneous elimination of microstructure defects are completed in a single process, which significantly improves the density, mechanical properties and forming accuracy of aluminum alloy forgings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in 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 some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic flowchart of the semi-solid thixotropic forming method for spray-formed aluminum alloy blanks provided in Embodiment 1 of this application. Figure 2 This is a schematic diagram of a semi-solid thixotropic forming method for spray-formed aluminum alloy billets provided in Embodiment 1 of this application. Figure 3a This is a schematic diagram of the microstructure of the 7075 spray-formed aluminum ingot raw material provided in Embodiment 1 of this application; Figure 3b This is a schematic diagram of the semi-solid thixotropic deformation test of a cylindrical specimen provided in Embodiment 1 of this application; Figure 4a This is a comparative schematic diagram of the macroscopic outline of the cylindrical sample after semi-solid thixotropic deformation at different semi-solid temperatures, provided in Embodiment 1 of this application. Figure 4b This is a comparative schematic diagram of the microstructure of the cylindrical sample after semi-solid thixotropic deformation at different semi-solid temperatures, provided in Embodiment 1 of this application. Figure 5This is a schematic diagram of the microstructure evolution and defect repair characteristic curves of different strain regions inside the cylindrical sample provided in Embodiment 1 of this application after being held at a semi-solid temperature of 570°C for 60 seconds. Figure 6 This is a schematic flowchart of the semi-solid thixotropic forming method for spray-formed aluminum alloy billets provided in Embodiment 2 of this application. Figure 7 This is a schematic diagram of a semi-solid thixotropic forming method for spray-formed aluminum alloy billets provided in Embodiment 2 of this application. Figure 8 This is a schematic diagram of the semi-solid thixotropic forming system for spray-formed aluminum alloy blanks provided in the embodiments of this application; Figure 9 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0024] 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 with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] To better understand the embodiments of this application, the prior art will first be described in detail: In existing technologies, although spray forming technology can produce high-performance aluminum alloy preforms, it is constrained by the condensation characteristics during the droplet deposition process. As a result, defects such as micropores, porosity, and lack of interlayer fusion inevitably exist inside the preform, which directly weakens the mechanical properties and forming accuracy of the parts.

[0026] Current solutions have the following limitations: First, the repair process is redundant, requiring subsequent hot isostatic pressing or multiple secondary forgings to repair internal defects, resulting in a long and costly process chain, and repeated thermal cycles can easily lead to microstructure coarsening. Second, the function is singular; traditional semi-solid forming research focuses on improving the rheological filling ability of materials (i.e., macroscopic shape control), while lacking in-depth synchronous process research on how to utilize liquid phase flow in the semi-solid state to achieve active healing of micro-defects (i.e., microscopic quality control). Finally, high-alloy aluminum alloys are difficult to form, especially for 7xxx series ultra-high strength aluminum alloys, where existing technologies cannot simultaneously achieve precise filling of complex geometries and complete elimination of internal micro-defects in a single forming process.

[0027] To address the aforementioned technical problems, this application provides a semi-solid thixotropic forming method for spray-formed aluminum alloy billets. This method, through precise and coordinated control of heating temperature, liquid phase fraction, and segmented pressure, establishes a process logic of "simultaneous macroscopic forming and microscopic defect repair." This process not only significantly improves material utilization but also enables parts to achieve a continuous, dense microstructure close to theoretical density without hot isostatic pressing, resulting in a significant improvement in tensile strength and fatigue performance.

[0028] It should be noted that the above-mentioned semi-solid thixotropic forming method for spray-formed aluminum alloy blanks can be applied to cutting-edge manufacturing fields that have dual requirements for high density, high reliability, and complex structures. For example, it can be used in the aerospace field to manufacture load-bearing components, load-bearing rods, and high-strength plates with complex ribs and deep cavities; in the automotive and rail transportation field to produce high-performance aluminum alloy wheels, steering knuckles, complex housings, and shock-absorbing structural components, contributing to vehicle lightweighting; and in the high-end machinery manufacturing field to manufacture precision structural components requiring high fatigue life and various irregularly shaped high-strength aluminum alloy components.

[0029] It should be noted that the execution subject involved in the embodiments of this application can be a semi-solid thixotropic forming method device for spray-formed aluminum alloy billets, or it can be an electronic device. Optionally, the electronic device may include: a computer / laptop, a mobile terminal, a server, electronic assembly equipment, and electrical production equipment, etc.

[0030] Furthermore, the spray-formed aluminum alloys involved in this application have wide compositional applicability, including but not limited to 7xxx series ultra-high strength aluminum alloys (such as 7075 aluminum alloy) and various compositionally modified alloys. This semi-solid thixotropic forming method is applicable to spray-formed aluminum alloy blanks in various initial forms such as block, plate, and preform, and has good compatibility, ensuring the versatility and flexibility of this semi-solid thixotropic forming method in different industrial production scenarios.

[0031] The following uses an electronic device as an example to illustrate in detail the semi-solid thixotropic forming method for spray-formed aluminum alloy billets provided in the embodiments of this application: Example 1 Figure 1 This is a schematic flowchart of the semi-solid thixotropic forming method for spray-formed aluminum alloy blanks provided in Embodiment 1 of this application. Figure 2 This is a schematic diagram illustrating a scenario of the semi-solid thixotropic forming method for spray-formed aluminum alloy blanks provided in Embodiment 1 of this application. It should be noted that Embodiment 1 is a semi-solid thixotropic forming method for spray-formed aluminum alloy components with relatively regular shapes. For example, it is suitable for simple shells, thick-walled pipes, wheel hubs, or highly symmetrical disc-shaped components. Although these parts have relatively simple geometric structures, they have extremely high requirements for the density of their internal structure and the consistency of their mechanical properties.

[0032] Combination Figure 1 and Figure 2 It can be seen that the method includes the following steps 101-103.

[0033] Step 101: Heat the spray-formed aluminum alloy billet to the semi-solid temperature range so that the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 30% to 70%, forming a semi-solid slurry composed of solid phase spherical particles coated with a uniform liquid film.

[0034] Among them, spray-formed aluminum alloy billet refers to aluminum alloy preforms prepared using spray forming (also known as deposition forming) technology, which is also a type of raw billet.

[0035] The semi-solid temperature range refers to the temperature range between the solidus temperature and the liquidus temperature of a metallic material. Within this semi-solid temperature range, spray-formed aluminum alloy billets exhibit a solid-liquid coexistence state.

[0036] Liquid phase fraction refers to the percentage of molten metal (i.e., liquid phase) in the total volume or mass of an alloy within the semi-solid temperature range.

[0037] A semi-solid slurry with a uniform liquid film coating solid particles refers to a slurry state in which spherical solids are encapsulated by liquid at the microscopic level, exhibit fluidity at the macroscopic level, and have an extremely uniform structure. This semi-solid slurry is also a type of semi-solid preform. The microstructure of this semi-solid preform is characterized by near-spherical solid particles being uniformly coated by a continuous liquid phase.

[0038] In step 101, the electronic device places the spray-formed aluminum alloy billet in a heating device and heats it according to a preset heating curve. During the heating process, the electronic device monitors the surface and core temperatures of the billet in real time through a temperature sensor in the heating device, dynamically adjusting the heat input to minimize the temperature gradient. Under the effect of thermo-mechanical coupling, the low-melting-point phase inside the billet preferentially melts at the grain boundaries, and the original equiaxed fine-grained structure is passivated and undergoes spheroidization evolution under the thermal effect, forming stable solid-phase spheroids. At the same time, the newly generated liquid phase spreads fully along the solid-phase spheroid interface under the drive of surface tension, forming a uniform liquid film that completely covers the solid-phase spheroids. Finally, the electronic device controls the heating device to precisely lock the liquid phase fraction at 30% to 70%, transforming the spray-formed aluminum alloy billet from a solid state into a semi-solid slurry with excellent filling ability and thixotropic flowability.

[0039] Optionally, the heating device can be an induction heating device, a resistance heating furnace, or other high-precision temperature-controlled heating equipment. This heating device achieves uniform temperature control of the spray-formed aluminum alloy billet through resistive radiation, induction coil heating, or convection heat transfer, combined with multi-point closed-loop feedback control.

[0040] Optionally, the preset heating curve can be a "time-temperature-liquid phase fraction" correlation model pre-set based on the composition system of the spray-formed aluminum alloy billet. The electronic device calculates this correlation model using real-time collected temperature data and dynamically adjusts the output power of the heating device to ensure that the growth rate and spatial distribution of the liquid phase fraction inside the spray-formed aluminum alloy billet meet process requirements after entering the semi-solid temperature zone, thereby obtaining a semi-solid billet with extremely uniform microstructure. This control strategy ensures that the precipitation of the liquid phase at the grain boundaries meets the thixotropic flow requirements without causing liquid phase enrichment or segregation due to local overheating, thus obtaining a semi-solid billet with highly uniform macroscopic and microscopic microstructure.

[0041] Optionally, the electronic device monitors the surface and core temperature data of the spray-formed aluminum alloy billet in real time and performs online simulations in conjunction with the aforementioned correlation model. When it is determined that the internal liquid phase fraction reaches the preset process window of 30% to 70%, the electronic device automatically triggers a high-precision heat preservation mode or issues an automated furnace exit command to ensure that the semi-solid slurry has stable rheological parameters before entering the subsequent forming process.

[0042] It should be noted that by controlling the preset heating curve and minimizing the temperature gradient, not only is the rapid coarsening of the non-dendritic fine-grained structure unique to spray-formed aluminum alloy billets at high temperatures effectively suppressed, maximizing the preservation of the material's high-performance matrix advantages, but the internal structure of the spray-formed aluminum alloy billets can also be precisely transformed into an ideal thixotropic structure of solid-phase spherules covered by a uniform liquid film under thermal effects. This thixotropic structure significantly reduces the deformation resistance during the forming process, giving the spray-formed aluminum alloy billets excellent filling ability. On the other hand, by locking the liquid phase fraction within a specific range, a continuous liquid phase fluid channel is established. This provides a key material basis for eliminating micropores and achieving interlayer non-fusion metallurgical bonding in the subsequent segmented pressure process using the capillary effect, thereby fundamentally solving the problem of internal porosity in spray-formed aluminum alloy forgings and ensuring the densification and mechanical property consistency of the target aluminum alloy forgings.

[0043] The following section details how electronic devices heat spray-formed aluminum alloy billets to a semi-solid temperature range, causing the internal liquid phase fraction of the billets to reach 30%–70%, forming a semi-solid slurry composed of solid-phase spherical particles coated with a uniform liquid film: In some embodiments, the heating process of the spray-formed aluminum alloy billet by the electronic device is specifically divided into three stages: In the first stage, the spray-formed aluminum alloy billet is rapidly heated from room temperature to 50°C below the solidus temperature at a heating rate of ≥10°C / s to obtain a first aluminum alloy billet; In the second stage, the first aluminum alloy billet is heated to the solidus temperature and held at that temperature so that the temperature difference between the center and the surface of the first aluminum alloy billet is ≤10°C to obtain a second aluminum alloy billet; In the third stage, the second aluminum alloy billet is heated from the solidus temperature to a target semi-solid temperature within the semi-solid temperature range to obtain the semi-solid slurry, wherein the target semi-solid temperature corresponds to a liquid phase fraction of 30% to 70% and represents the liquidus temperature.

[0044] The target semi-solid temperature refers to a predetermined temperature point at which the spray-formed aluminum alloy billet reaches a preset liquid phase fraction equilibrium state. At this target semi-solid temperature, the liquid phase fraction is in the range of 30% to 70%, which ensures that the semi-solid slurry has sufficient thixotropic fluidity and maintains the macroscopic geometry of the billet through the solid phase skeleton.

[0045] In this embodiment of the application, the electronic device controls the heating device to perform a segmented heating process on the spray-formed aluminum alloy billet. In the first stage, the electronic device controls the heating device to rapidly heat the spray-formed aluminum alloy billet from room temperature to 50°C below the solidus temperature (e.g., to 480°C to 500°C) at a heating rate of ≥10°C / s, thereby obtaining the first aluminum alloy billet.

[0046] In the second stage, the electronic device controls the heating device to continue heating the first aluminum alloy billet to the solidus temperature and hold it at that temperature for a short time. The electronic device adjusts the heating power and frequency (such as the induction heating frequency) to keep the temperature difference between the center and the surface of the first aluminum alloy billet within 10°C, thus obtaining the second aluminum alloy billet.

[0047] In the third stage, the electronic device controls the heating device to heat the second aluminum alloy billet from the solidus temperature to the target semi-solid temperature in the semi-solid temperature range (this temperature corresponds to a liquid phase fraction of 30% to 70%). At this target semi-solid temperature, the electronic device controls the heating device to perform constant temperature holding for 60 to 120 seconds, using thermal activation energy to drive atomic diffusion, causing partial melting of grain boundaries and inducing spheroidization evolution of the solid phase structure, ultimately forming a semi-solid slurry with solid phase spheroids covered by a uniform liquid film.

[0048] During this heating process, the electronic equipment uses real-time temperature data and a preset heating curve for closed-loop feedback. By dynamically adjusting the output parameters of the heating device (such as the magnitude of the induced current), the temperature fluctuation of the spray-formed aluminum alloy billet is controlled within ±2°C. Once the spray-formed aluminum alloy billet reaches the target semi-solid temperature and completes the preset holding time, the electronic equipment determines that the semi-solid slurry composed of solid-phase spherical particles coated with a uniform liquid film has been prepared. This heating process is also a method of preparing a semi-solid billet.

[0049] It should be noted that the above three-stage precise temperature control process achieves "on-demand customization" of the microstructure of the spray-formed aluminum alloy billet. The first stage, through ultra-rapid heating, aims to shorten the residence time of the spray-formed aluminum alloy billet in the high-temperature solid phase region by utilizing an extremely high heating rate, thus suppressing the coarsening of the fine-grained structure unique to spray forming. The second stage, through the balance of heat conduction and inductive heating, eliminates the temperature gradient inside the spray-formed aluminum alloy billet, laying the foundation for the uniform precipitation of the subsequent liquid phase. The third stage, through isothermal induced spheroidization, utilizes thermal activation energy to drive atomic diffusion, causing the microstructure to evolve into an ideal thixotropic structure of "liquid film-coated solid spheres." The uniform, interconnected liquid phase network formed in this state not only significantly reduces forming resistance, but more importantly, this uniform, interconnected liquid phase network provides a physical carrier and micro-fluid channels for eliminating defects such as micropores, porosity, and interlayer incomplete fusion in subsequent steps, fundamentally ensuring the high density and performance consistency of the target aluminum alloy forging.

[0050] Step 102: Place the semi-solid slurry in the lower mold of the forming mold, and use a segmented pressure control process to control the upper mold of the forming mold to press down, so that the semi-solid slurry completes defect repair and forming in the closed cavity, and obtains the deformed aluminum alloy forging.

[0051] The forming mold refers to a precision mold system used to impart a specific geometry to a semi-solid slurry and provide pressure for defect repair. The forming mold includes an upper mold and a lower mold with cavity features; the internal space formed when the two are fully closed is called a closed cavity. Optionally, the forming mold can be a unidirectional pressing or multidirectional pressing structure.

[0052] Optionally, before placing the semi-solid slurry into the lower mold of the forming mold, the mold cavity is preheated. The preheating temperature range can be 250°C to 350°C to reduce the temperature difference between the semi-solid slurry and the forming mold. This preheating process effectively maintains the flow activity of the liquid phase by suppressing the chilling effect of the semi-solid slurry during the filling process, ensuring the filling accuracy of small features such as deep ribs and narrow grooves. At the same time, it significantly reduces the thermal shock stress on the surface of the forming mold, thus significantly extending the service life of the forming mold while ensuring the geometric integrity of the aluminum alloy forging.

[0053] Segmented pressure control technology refers to a process in which electronic equipment controls the forming device to apply pressure commands of different magnitudes, speeds, and durations at different stages of the forming process.

[0054] Optionally, the forming apparatus may employ a servo press, hydraulic press, or dedicated hydraulic forming system, capable of providing pressure-displacement-speed closed-loop control with millisecond-level response to ensure precise execution of the segmented process.

[0055] In step 102, after acquiring the semi-solid slurry, the electronic device controls the forming device to place the semi-solid slurry in the lower mold of the forming mold, and calls the forming device to use a segmented pressure control process to control the upper mold of the forming mold to press down, so that the semi-solid slurry completes defect repair and forming in the closed cavity, and obtains the deformed aluminum alloy forging.

[0056] It should be noted that by using electronic devices to drive the forming device to implement precise segmented pressure control, the pressure, speed and duration are adjusted in stages within the closed cavity of the forming mold. This not only achieves precise filling of complex shapes, but also effectively drives the semi-solid slurry to complete the repair of internal defects, ensuring the synergistic improvement of the macroscopic shape and microstructure density of the final aluminum alloy forging.

[0057] The following section details how, in electronic devices, a semi-solid slurry is placed in the lower mold of a forming die, and the upper mold of the forming die is controlled by a segmented pressure control process to allow the semi-solid slurry to complete defect repair and forming within a closed cavity, resulting in a deformed aluminum alloy forging: In some embodiments, the electronic device uses a first pressure in a first pressure section to control the upper die of the forming mold to press down, utilizing the superplastic flow characteristics of the liquid phase in the semi-solid slurry to remove internal gas from the semi-solid slurry, thereby obtaining a prototype of the target aluminum alloy forging; the electronic device uses a second pressure in a second pressure section to control the upper die of the forming mold to continue pressing down, utilizing the capillary effect to drive the liquid phase in the semi-solid slurry to penetrate into the micropores inside the semi-solid slurry, thereby filling and repairing the porosity and interlayer non-fusion defects in the prototype of the target aluminum alloy forging, thereby obtaining a repaired part of the target aluminum alloy forging; the electronic device uses a third pressure in a third pressure section to control the upper die of the forming mold to continue pressing down, thereby forcibly plastically deforming the repaired part of the target aluminum alloy forging to obtain the deformed aluminum alloy forging.

[0058] The first pressure stage refers to the initial stage where the upper mold of the forming die, driven by electronic equipment, contacts the semi-solid slurry and begins to apply pressure.

[0059] The second pressure stage refers to the defect repair stage that the electronic device enters after the upper mold displacement of the forming mold tends to level off or the cavity is basically filled.

[0060] The third pressure stage refers to the compaction stage where peak pressure is applied in the final stage of the forming of electronic devices.

[0061] The superplastic flow characteristics of the liquid phase refer to the lubricating effect of the liquid film wrapped around the surface of the solid particles in the initial stage of semi-solid slurry under pressure. This allows the solid particles to undergo large-scale displacement, sliding and rotation, thus giving the semi-solid slurry extremely low deformation resistance and excellent filling capacity.

[0062] The prototype of the target aluminum alloy forging refers to the intermediate billet that has been processed in the first pressure stage, and whose macroscopic shape has been initially filled into the cavity, but still contains trace amounts of gas and microscopic pores.

[0063] The capillary effect refers to the physical phenomenon in which the additional pressure generated by the tiny gaps between solid particles drives a lubricating liquid metal to automatically draw in and fill micropores under the synergistic effect of a pressure gradient.

[0064] Micropores, porosity, and interlayer non-fusion defects collectively refer to the inherent deposition defects in the spray forming process. Among them, micropores and porosity refer to tiny voids between solid particles, while interlayer non-fusion refers to weak interfacial bonding areas formed during droplet deposition due to excessively rapid condensation.

[0065] Repaired aluminum alloy forgings refer to components that have undergone the second pressure stage treatment, in which internal micro-defects have been filled by the liquid phase and achieved metallurgical bonding, resulting in a significant increase in density, but have not yet completed the final plastic shaping.

[0066] In this embodiment, the electronic device first controls the forming apparatus to drive the upper die of the forming mold into the first pressure section and apply a first pressure. At this time, the electronic device utilizes the superplastic flow characteristics of the semi-solid slurry liquid phase to make the semi-solid slurry spread rapidly and fill the cavity, while the gas remaining inside the semi-solid slurry is discharged through the gap of the forming mold, thus obtaining a prototype of the target aluminum alloy forging. Subsequently, the electronic device controls the forming apparatus to drive the upper die of the forming mold to continue applying a second pressure. In this second pressure section, the electronic device utilizes the capillary effect to guide the directional flow of the liquid phase, so that the liquid phase in the semi-solid slurry penetrates into the micropores, porosity, and interlayer unfusion defects in the prototype of the target aluminum alloy forging, realizing the physical filling and metallurgical repair of the defects, thereby obtaining a repaired part of the target aluminum alloy forging. Finally, the electronic device switches to the third pressure stage. The electronic device controls the forming device and drives the upper die of the forming mold to apply the third pressure with a peak load. The electronic device performs forced plastic deformation on the repair part of the target aluminum alloy forging, eliminates the residual liquid-solid gap and compacts the structure until the displacement stabilizes within the preset tolerance range, thereby obtaining the deformed aluminum alloy forging.

[0067] Optionally, the electronic device achieves precise switching between different pressure stages through a multi-sensor fusion mechanism. Specifically, the switching method from the first pressure stage to the second pressure stage involves the electronic device acquiring the displacement curve and feedback stress of the upper mold of the forming die in real time through a displacement sensor. When it is determined that the current pressing speed has dropped to 10% to 20% of the initial speed, and the feedback stress reaches the threshold of the first pressure stage (e.g., 49% of the rated total pressure), it is determined that the semi-solid slurry has completed the macroscopic filling and venting of the cavity, and then it switches to the second pressure stage, using a constant or slowly increasing pressure gradient to drive liquid phase penetration. The switching method from the second pressure stage to the third pressure stage involves the electronic device performing the switching based on both time and displacement criteria. In the second pressure stage, a pressure holding period of 3 to 10 seconds is performed to ensure that the capillary effect occurs fully. If the displacement sensor detects that the displacement increment is within the preset tolerance range multiple times during this period, it is determined that the micro-defects have been metallurgically repaired, and the electronic device immediately controls the forming device to instantaneously increase the pressure to the third pressure stage (80% to 100% of the rated total pressure) to perform final forced plastic compaction on the repaired aluminum alloy forging.

[0068] It should be noted that this segmented pressure control process cleverly utilizes the differences in physical properties of semi-solid slurry under different pressure conditions. Through a three-step strategy of "venting the initial layer, infiltration repair, and forced densification," it solves the process problem of "easy filling but difficult densification" in spray-formed aluminum alloys. Specifically, the first pressure stage ensures precise filling of complex irregular parts, while the second pressure stage utilizes liquid infiltration at the microscale to transform the originally fragile interlayer interface into a continuous metallurgical structure, completely eliminating the incomplete fusion defects inherent in the deposition process. By dynamically adjusting the pressure switching point, the risk of liquid phase being squeezed out and solid phase accumulation due to sudden pressure changes is avoided, ensuring a high degree of uniformity in the overall structure and properties of the forging. Finally, because internal defects are completely eliminated, the final target aluminum alloy forging can meet or even exceed the standards of traditional heat treatment in terms of fatigue life and tensile strength, meeting the high reliability requirements of key structural components.

[0069] In some embodiments, the electronic device uses a pressure of 20% to 49% of the rated total pressure in the first pressure section. Under the action of the first pressure, the semi-solid slurry undergoes grain boundary sliding and rotation, and initially fills the deep ribs and narrow grooves of the forming mold.

[0070] The rated total pressure refers to the maximum target load preset based on the rated load of the forming device and the unit forming pressure required for the target aluminum alloy forging. For example, the rated total pressure can range from 50 to 100 MPa.

[0071] The first pressure ranges from 20% to 49% of the rated total pressure.

[0072] Grain boundary sliding and rotation refer to the relative displacement and rotation behavior of solid particles along the liquid phase layer under stress during the compression process of semi-solid slurry. This is because the solid particles are completely covered by a uniform liquid film, and the frictional resistance between the particles is extremely small.

[0073] Deep ribs and narrow grooves refer to geometric areas in the cavity of a forming mold that have a high aspect ratio and narrow gaps.

[0074] In this embodiment, the electronic device first controls the forming device to drive the upper mold of the forming mold to press down and switch to the first pressure segment, locking the output pressure at 20% to 49% of the rated total pressure. Using the first pressure in the first pressure segment, the electronic device drives the slurry to trigger grain boundary sliding and rotation through low pressure, so that the semi-solid slurry can preferentially spread and penetrate into the deep ribs and narrow grooves of the forming mold without causing serious liquid-solid segregation.

[0075] It should be noted that by controlling the initial pressure at 20%–49% of the rated total pressure, the aim is to achieve low-resistance filling by utilizing the fluid-like properties of the semi-solid slurry. This stage induces grain boundary sliding and rotation, allowing the metal to smoothly fill complex cavities such as deep ribs and narrow grooves, ensuring the geometric integrity of the aluminum alloy forging. Simultaneously, the low-pressure initial filling effectively suppresses the risk of liquid-solid segregation caused by excessive pressure, ensuring uniform composition and microstructure in both thin-walled and thick-walled sections. Furthermore, the lower initial load reduces the scouring loss of the cavity walls caused by metal flow, significantly extending the service life of the forming die.

[0076] In some embodiments, the electronic device uses a pressure of 50% to 79% of the rated total pressure in the second pressure section and a pressure holding time of 3 to 10 seconds. The pressure gradient established by the second pressure is used to coordinate with the capillary pressure generated by the surface tension of the liquid phase in the semi-solid slurry, guiding the liquid phase in the semi-solid slurry to converge towards the micron-level loose and interlayer unfused defects and to undergo metallurgical bonding.

[0077] The value range of the second pressure is 50% to 79% of the rated total pressure.

[0078] Metallurgical bonding is the atomic-level fusion that occurs at the interface between the liquid phase filling defects in a semi-solid slurry and the original solid phase particles, restoring the continuity of the metallic material.

[0079] In this embodiment, after determining that the cavity of the forming mold has been initially filled, the electronic device quickly switches the output pressure to 50% to 79% of the rated total pressure and starts a high-precision timer to maintain pressure for 3 to 10 seconds. During this process, the electronic device controls the forming device to maintain a stable load output, establishing a pressure gradient from the outside to the inside within the semi-solid slurry. This pressure gradient, combined with the capillary pressure caused by the surface tension of the liquid phase, forms the driving force for the directional migration of the liquid phase, forcibly guiding the liquid phase to converge to defects such as micropores, looseness, and lack of interlayer fusion, thereby completing metallurgical bonding and obtaining a repaired part of the target aluminum alloy forging.

[0080] It should be noted that this step, by precisely controlling the medium pressure range of 50% to 79% of the rated total pressure, provides sufficient power to drive liquid phase permeation, and by protecting the morphology of the solid phase skeleton, avoids the liquid phase flow channel being blocked due to the pressure reaching the peak too early, thus ensuring the thoroughness of defect repair.

[0081] In some embodiments, the electronic device uses a pressure of 80% to 100% of the rated total pressure in the third pressure section to force plastic deformation of the repair part of the target aluminum alloy forging.

[0082] Forced plastic deformation refers to applying peak pressure to the repaired aluminum alloy forging that has already undergone defect repair, causing the solid particles to undergo extrusion deformation, displacement filling, and interface compaction, thereby eliminating residual micro-liquid-solid gaps.

[0083] In this embodiment, after the pressure holding period, the electronic device controls the forming device to drive the upper die of the forming mold to press down with full force, increasing the pressure to 80% to 100% of the rated total pressure (e.g., the third pressure). The electronic device ensures that the upper die of the forming mold reaches the final preset position through displacement feedback. Under this high pressure, the solid-phase skeleton inside the repaired part of the target aluminum alloy forging undergoes forced plastic deformation, further densifying the microstructure and locking in the final dimensional accuracy of the part. When the electronic device detects that the displacement no longer changes within a set time, it determines that the forming process is complete.

[0084] It should be noted that this step, through forced mechanical compaction, completely eliminates residual, extremely small liquid-solid gaps, refines the microstructure, and eliminates micro-regional component segregation that may be caused by liquid phase aggregation. Simultaneously, displacement increment feedback ensures that the final preset size value is achieved, thereby locking in the geometric accuracy and high fatigue resistance of the part.

[0085] In some embodiments, during the segmented pressure control process, the upper die of the forming mold is pressed down at a variable speed. The variable speed control includes: in a first pressure segment, controlling the upper die of the forming mold to press down at a first speed, so that the semi-solid slurry is in a superplastic flow state; in a second pressure segment, controlling the upper die of the forming mold to press down at a second speed, the second speed being less than the first speed, and increasing the holding time, so as to utilize the capillary effect to allow the liquid phase in the semi-solid slurry to fully penetrate into the porous and interlayer unfused defects in the prototype of the target aluminum alloy forging.

[0086] In this embodiment, when entering the first pressure stage, the electronic device controls the forming device to drive the upper mold of the forming mold to press down rapidly at a preset first speed. During this stage, the electronic device makes full use of the superplastic flow state exhibited by the semi-solid slurry under high-speed shear force, so as to cause the semi-solid slurry to spread rapidly in the cavity and fill the complex contour. Before the liquid phase condenses, the macroscopic filling of complex contours such as deep ribs and narrow grooves is completed, and the residual gas is efficiently discharged by using the propulsion effect of the metal wavefront. Subsequently, when the electronic device detects through the displacement sensor that the pressing speed has dropped to 10% to 20% of the initial speed (i.e., the first speed), or determines that the feedback load has reached the threshold of the first pressure segment, it simultaneously executes a deceleration command while switching to the second pressure segment. The electronic device reduces the current pressing speed to a second speed that is significantly lower than the first speed, entering a low-speed pressing mode. In this low-speed stage, since the second speed is significantly lower than the first speed, the electronic device effectively reduces the dynamic impact force between solid particles, thereby suppressing the liquid-solid two-phase separation that may be caused by high-speed extrusion. At the same time, the electronic device, combined with the aforementioned 3 to 10-second delay pressure holding strategy, provides a sufficient dynamic response window for the capillary effect, driving the liquid metal to fully penetrate into the micropores, looseness, and unfused interlayer areas of the target aluminum alloy forging prototype under a constant pressure gradient, ensuring the thoroughness of metallurgical repair.

[0087] It should be noted that the high-speed downward pressure in the first pressure stage ensures that the semi-solid slurry completes macroscopic filling before the semi-solid liquid phase condenses. The deceleration and pressure holding in the second pressure stage provides a necessary time window for microscopic liquid-phase penetration repair, avoiding liquid phase loss or incomplete repair due to excessively rapid downward pressure. Simultaneously, variable speed control effectively prevents severe liquid-solid segregation of the semi-solid slurry at the end of filling. The lower second speed reduces the dynamic impact force between solid particles, allowing for more uniform cooperation between the solid and liquid phases during the defect repair stage, ensuring consistent density in both complex thin-walled and thick-walled areas. Therefore, the final aluminum alloy forging not only has a clear surface contour and no folding defects, but also achieves extremely high internal metallurgical quality, significantly improving the material's fatigue resistance.

[0088] In some embodiments, after step 102, the method further includes: before entering the third pressure stage, the electronic device cyclically uses the pressure in the first pressure stage and the pressure in the second pressure stage according to the displacement of the upper mold of the forming mold or a set time threshold, and controls the upper mold of the forming mold to continue to press down, so that the semi-solid slurry completes defect repair in the closed cavity.

[0089] The displacement refers to the real-time travel value of the upper mold relative to the starting position or the lower mold reference plane. Electronic equipment obtains the displacement of the upper mold through a displacement sensor (such as a grating ruler or laser rangefinder) installed on the upper mold, in order to determine the filling height of the semi-solid slurry in the cavity and the instantaneous deformation of the semi-solid slurry.

[0090] The set time threshold refers to the upper limit of the duration or switching cycle pre-stored in the electronic device for different pressure stages. This time threshold is determined based on the rheological properties of spray-formed aluminum alloy billets at a specific liquid phase fraction and is used to trigger the alternating cycle of different pressure stages.

[0091] In this embodiment, after determining that the semi-solid slurry has completed its initial filling, the electronic device enters a dynamic "pumping" defect repair mode: the electronic device monitors the displacement of the upper mold in real time. When the displacement rate tends to stagnate or reaches a set time threshold, the electronic device does not directly enter the third pressure stage, but instead drives the forming device to switch back and forth between the first and second pressure stages. Specifically, the electronic device first drives the forming device to apply a lower pressure in the first pressure stage to cause slight rheological disturbance in the semi-solid slurry, and then rapidly increases the pressure to the second pressure stage to generate extrusion and penetration; then it decreases the pressure back to the first pressure stage to release the locally accumulated elastic strain. At this time, the electronic device issues a command to increase the pressure to the second pressure stage again according to the preset cycle parameter logic, thereby constructing a periodic pressure alternation command chain between the first and second pressure stages. Through this cyclic fluctuation of high and low pressure, the semi-solid slurry in the closed cavity is subjected to multiple "pressurization-relaxation-repressurization" disturbances until the displacement reaches the final repair preset value, thereby guiding the liquid phase to more thoroughly fill the micropores and complete the defect repair.

[0092] It should be noted that this cyclic control strategy disrupts the flow balance of the liquid phase inside the semi-solid slurry through dynamic loading. On the one hand, the micro-shear force generated by the reciprocating pressure disturbance can effectively break the fine oxide film between the spray-formed layers, clearing obstacles for metallurgical bonding; on the other hand, by utilizing the cyclic logic of "pressure penetration-pressure relaxation", a dynamic effect similar to a pulse pump is generated, which significantly enhances the power of the liquid phase to fill the deep micron-level porous layers, ensuring that complex aluminum alloy components achieve an extremely high degree of densification without increasing the overall forming load.

[0093] Step 103: Cool and solidify the deformed aluminum alloy forging to obtain the target aluminum alloy forging.

[0094] Cooling and solidification refers to the process by which the deformed aluminum alloy forging is cooled from the semi-solid temperature zone to below the solidus temperature under the constraint of the forming mold, so that the liquid phase component is completely solidified and combined with the solid phase skeleton into a whole.

[0095] In step 103, the electronic device controls the forming device to cool and solidify the deformed aluminum alloy forging until the temperature of the deformed aluminum alloy forging drops below the solidus temperature. Then, the forming device is controlled to drive the target aluminum alloy forging to be demolded.

[0096] It should be noted that the forming die in step 102 is an integral forming die. The closed cavity of this forming die matches the shape of the target aluminum alloy forging. This forming die can be a thixotropic forging die. This integral forming die ensures the dimensional tolerance stability of the forging during the high-pressure forming process, ensuring that the target aluminum alloy forging not only has high internal microstructure consistency but also excellent surface integrity, reducing the allowance for subsequent machining. Step 103, through controlled cooling rate, can quickly lock in the excellent spheroidized microstructure and dense microstructure obtained in the semi-solid processing stage, shortening the residence time of the forging in the high-temperature range. This effectively prevents secondary coarsening of solid grains and abnormal growth of precipitates during the cooling process, ensuring that the target aluminum alloy forging has a microstructure basis of high strength and high toughness.

[0097] The following section details the process of cooling and solidifying deformed aluminum alloy forgings using electronic devices to obtain the target aluminum alloy forging: In some embodiments, while keeping the forming mold in a closed state, the electronic device maintains the pressure of the upper die of the forming mold at the pressure in the third pressure segment, and after a preset time, cools the deformed aluminum alloy forging to obtain the target aluminum alloy forging.

[0098] In this embodiment, after the forced plastic deformation action in step 102 is completed, the electronic device immediately drives the forming device to maintain the forming mold in a closed state and continuously applies pressure in the third pressure segment (e.g., the third pressure). Subsequently, the electronic device maintains this pressure for a preset duration (e.g., 5s to 15s) and activates the cooling logic by adjusting the mold cooling system (e.g., circulating cooling water or a spray device), causing the deformed aluminum alloy forging to cool down at a controlled rate. During this process, the electronic device monitors the feedback data from the integrated temperature sensor within the forming mold in real time until the core temperature of the deformed aluminum alloy forging drops below the solidus temperature, determining that the liquid metal phase has completely solidified and the microstructure has been finalized. Finally, the electronic device issues an unloading command, controlling the forming device to open the upper mold of the forming mold and perform a demolding action to obtain the target aluminum alloy forging. This target aluminum alloy forging is also a final product. Based on the preparation of a semi-solid billet by heating, the final product can be obtained by performing steps 102 and 103 above. The final product exhibits a clear surface contour and extremely high geometric integrity. Furthermore, the discrete pores originally present in the semi-solid billet have essentially disappeared, and the microstructure has become dense and continuous. This process is also a semi-solid thixotropic forging process. During this process, the semi-solid billet undergoes semi-solid thixotropic flow. Under pressure, the capillary effect drives the liquid phase to penetrate into micropores and loose areas, achieving pore filling.

[0099] It should be noted that the "pressure-holding cooling" logic implemented through electronic devices utilizes continuous external mechanical pressure to compensate for the volume shrinkage of the metal during the solidification stage due to phase transformation, thereby completely eliminating secondary defects such as shrinkage cavities, hot cracks, and shrinkage porosity at the microscopic level. Because a one-piece forming die (such as a thixotropic forging die) is used, this controlled solidification process not only achieves physical locking of the fine spheroidized structure but also minimizes the thermal shrinkage deformation of the aluminum alloy forging through the strong rigidity constraint of the forming die, ensuring that the final target aluminum alloy forging possesses extremely high dimensional tolerance accuracy and excellent mechanical property stability.

[0100] To better understand the above embodiment one, a cylindrical sample selected from the raw material of 7075 spray-formed aluminum ingot using wire cutting process is used as the original billet for verification.

[0101] Figure 3a This is a schematic diagram of the microstructure of the 7075 spray-formed aluminum alloy cylindrical blank provided in Embodiment 1 of this application; Figure 3b This is a schematic diagram of a semi-solid thixotropic deformation test of a cylindrical specimen provided in Embodiment 1 of this application. Combined with... Figure 3a and Figure 3bIt can be seen that the microstructure of the original billet exhibits typical spray forming characteristics: the original billet grains contain uniformly and discretely distributed eutectic compounds (indicated by gray arrows), and there are irregularly shaped, unevenly sized, and unevenly distributed pores between the grains (indicated by black arrows).

[0102] First, the electronic device performs step 101 above by heating the cylindrical sample to different semi-solid temperatures (such as 510°C, 540°C, 570°C, and 600°C) at a rate of 10°C / s and holding it at that temperature for 60 seconds, thus successfully preparing semi-solid billets with different liquid phase fractions. Figure 4a This is a comparative schematic diagram of the macroscopic outline of the cylindrical sample after semi-solid thixotropic deformation at different semi-solid temperatures, provided in Embodiment 1 of this application. Figure 4b This is a comparative schematic diagram of the microstructure of the cylindrical sample provided in Embodiment 1 of this application after semi-solid thixotropic deformation at different semi-solid temperatures. Figure 4a and Figure 4b It can be seen that as the heating temperature of the original billet increases, the internal microstructure of the billet will change significantly. The solid α-Al grains are gradually passivated and spheroidized under the action of the liquid phase. At lower temperatures (such as 510°C and 540°C), the liquid phase is mainly distributed at the grain boundaries. At higher temperatures (such as 570°C and 600°C), the liquid phase not only forms a continuous grain boundary network, but also appears in the grains in the form of dots. This indicates that the low melting point phase in the grains also undergoes local melting, forming more developed liquid phase channels.

[0103] Next, the electronic device performs step 102 above, setting the forming strain rate to 0.1 s⁻¹ (or 1.0 s⁻¹ in the thermal simulation test), and the total reduction to 8 mm. During this deformation process, the liquid phase flowing inside the semi-solid billet can effectively penetrate and fill the pores in the original billet under pressure.

[0104] Finally, after obtaining the deformed aluminum alloy forging in step 102, the electronic device executes step 103 to obtain the final product.

[0105] To further reveal the local microstructural response during the semi-solid thixotropic deformation process, a quantitative analysis was conducted on different strain regions inside a cylindrical sample deformed after holding at a semi-solid temperature of 570°C for 60 seconds. The main parameters included grain diameter, liquid volume fraction, grain shape factor, and void volume ratio. Figure 5 This is a schematic diagram of the microstructure evolution and defect repair characteristic curves of different strain regions inside the cylindrical sample provided in Embodiment 1 of this application after being held at a semi-solid temperature of 570°C for 60 seconds. Figure 5It can be seen that as the forming temperature increases from 510°C to 600°C, the grain diameter shows a steady growth trend. Around the target semi-solid temperature of 570°C, the grain size remains at a moderate level of about 55 μm, effectively avoiding excessive grain coarsening. The grain shape factor increases significantly with increasing temperature, reaching close to 0.7 at 570°C. This indicates that the solid-phase grains undergo sufficient passivation and spheroidization evolution under thermal effects, forming an ideal spherical or near-spherical structure, which greatly improves the thixotropic flowability of the semi-solid slurry. The liquid fraction curve shows that at 570°C, the liquid content of the original blank (Strain0.00) is about 18%, while the local liquid fraction in the deformed region (Strain0.90) increases dramatically with temperature. This indicates that at higher forming temperatures, the liquid phase is not only distributed in the grain boundary region, but also appears in the grain interior in the form of dots. As the heating temperature increases, the continuous melting of the grain boundaries and the spheroidization of the grains promote the formation of an interconnected liquid phase network and its fusion with the solid phase. This has a positive effect on reducing deformation resistance and improving thixotropic forming performance. The most crucial data is reflected in the significant decrease in porosity fraction. The porosity of the original billet (Strain 0.00) was approximately 18%–20%, while the porosity of the region after large strain (Strain 1.20) treatment plummeted to nearly 1%. This indicates that the sufficient outflow of the liquid phase under pressure produced a significant filling effect, which to some extent filled a large number of voids inside the cylindrical sample. From macroscopic to microscopic, this comprehensively reduced the number and volume ratio of voids in each region of the cylindrical sample. Therefore, the crack initiation at the edge of the cylindrical sample was also significantly reduced due to the reduction in the number of voids, greatly improving the edge forming quality of the aluminum alloy forging.

[0106] It should be noted that the data on specimen temperature, upper die stroke, and forming pressure during the semi-solid thixotropic forming test of the cylindrical specimen were collected and recorded by the thermal simulation testing machine platform. Figure 5 The experimental data comparison shows that the semi-solid temperature of 570°C is the optimal process point for achieving a balance between "shape control" and "quality control" in 7075 spray-formed aluminum alloy. At this temperature, by utilizing the synergistic effect of the capillary effect of the liquid phase and the segmented pressure control, the inherent deposition defects of the spray forming process can be eliminated to the greatest extent without causing severe segregation.

[0107] In this embodiment of the application, the technical solution described in steps 101-103 above involves heating the spray-formed aluminum alloy billet to a semi-solid temperature range, so that the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 30% to 70%, forming a semi-solid slurry composed of solid spherical particles coated with a uniform liquid film; placing the semi-solid slurry in the lower mold of the forming mold, and using a segmented pressure control process to control the upper mold of the forming mold to press down, so that the semi-solid slurry completes defect repair and forming in the closed cavity, obtaining a deformed aluminum alloy forging; and cooling and solidifying the deformed aluminum alloy forging to obtain the target aluminum alloy forging. This method, through the technical route of "fully constrained flow" and "efficient densification," organically combines the macroscopic geometric forming and microstructural defect repair of spray-formed aluminum alloy billets for the first time. It simultaneously completes forging and internal densification during a single-step semi-solid thixotropic forming process, breaking through the technical bottleneck of the traditional "form first, then repair" process. Addressing the common internal defects in spray-formed aluminum alloys, it provides an effective solution for defect elimination without additional high-cost equipment, significantly improving the internal microstructure quality of aluminum alloy forgings and enhancing service reliability. This contributes to promoting the engineering application of this aluminum alloy material in aerospace and high-end equipment fields. Utilizing the low deformation resistance of aluminum alloy materials in the semi-solid state, complex aluminum alloy components can be formed and densified on smaller tonnage equipment. Simultaneously, by reducing or eliminating expensive post-processing steps such as hot isostatic pressing, it significantly shortens the manufacturing cycle and reduces energy consumption and overall costs. It is not only applicable to 7xxx series ultra-high-strength aluminum alloys but also covers other spray-formed aluminum alloy systems. It can also be combined with unidirectional or multidirectional forming die structures and different types of equipment, demonstrating good process flexibility and expansion potential.

[0108] Example 2 Figure 6 This is a schematic flowchart of the semi-solid thixotropic forming method for spray-formed aluminum alloy billets provided in Embodiment 2 of this application. Figure 7 This is a schematic diagram illustrating a scenario of the semi-solid thixoforming method for spray-formed aluminum alloy billets provided in Embodiment 2 of this application. It should be noted that Embodiment 2 is a semi-solid thixoforming method for aluminum alloy components with complex geometries and high mechanical performance requirements. For example, it is suitable for core load-bearing components in the aerospace field that have multi-directional complex stiffeners, narrow and deep cavity structures, and which have stringent requirements for tensile strength, plasticity, and fatigue life under service conditions.

[0109] Combination Figure 6 and Figure 7 It can be seen that the method includes the following steps 201-203.

[0110] Step 201: Heat the spray-formed aluminum alloy billet to the semi-solid temperature range so that the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 50% to 65%, forming a semi-solid slurry composed of solid phase spherical particles coated with a uniform liquid film.

[0111] It should be noted that the formation process of the semi-solid slurry with an internal liquid phase fraction of 50% to 65% is similar to that of the semi-solid slurry with an internal liquid phase fraction of 30% to 70%, and will not be elaborated here. Furthermore, the semi-solid slurry is also a type of semi-solid preform, and step 201 is also a process of heating to prepare a semi-solid preform.

[0112] Step 202: Place the semi-solid slurry in the lower mold of the forming mold, and use a segmented pressure control process to control the upper mold of the forming mold to press down, so that the semi-solid slurry completes defect repair and forming in the closed cavity, and obtains the deformed aluminum alloy forging.

[0113] It should be noted that the scheme described in step 202 is similar to the scheme described in step 102 above, and will not be described in detail here.

[0114] However, it is important to note that the forming mold in step 202 is different from the forming mold in step 102. This is because the forming mold in step 101 is a one-piece forming mold, such as a thixotropic forging mold, while the forming mold in step 202 is a pre-forming mold. Step 202 is also a semi-solid thixotropic pre-forming (pore filling) process. In this process, electronic equipment controls the forming device to place the semi-solid billet in the pre-forming mold, and induces semi-solid thixotropic flow in the semi-solid billet by applying segmented pressure. Utilizing the superplasticity brought about by the high liquid phase fraction (50%–65%), the semi-solid billet rapidly fills the forming mold cavity, and simultaneously guides the liquid phase under pressure to penetrate into the microscopic defects of the original billet, completing the pore filling. The deformed aluminum alloy forging obtained by this process is a pre-formed part. The microstructure of this pre-formed part is characterized by nearly spherical solid particles and liquid phase distributed among them, with clear edges of the solid particles.

[0115] Step 203: Cool and solidify the deformed aluminum alloy forging to obtain the target aluminum alloy forging.

[0116] In step 203, the electronic device controls the forming device to cool and solidify the deformed aluminum alloy forging until the temperature of the deformed aluminum alloy forging drops below the solidus temperature. Then, the forming device is controlled to drive the target aluminum alloy forging to be demolded.

[0117] It should be noted that step 203 is also a process of final forming (microstructure refinement) in die forging. In this process, the preform is reheated to the solid temperature range and placed in the final forming mold. Electronic equipment controls the upper die of the forming mold to apply peak pressure, causing the preform to undergo severe plastic deformation in the all-solid state. This large strain process triggers the dynamic recrystallization mechanism inside the metal, forcibly breaking down the coarse microstructure generated in the semi-solid thixotropic preforming process.

[0118] The following section details the cooling and solidification process used by the electronic device to obtain the target aluminum alloy forging: In some embodiments, the electronic device cools the deformed aluminum alloy forging to obtain a third aluminum alloy billet; the third aluminum alloy billet is heated again to reach a preset solid phase temperature range to obtain a fourth aluminum alloy billet; the fourth aluminum alloy billet is placed in the lower die of the target forging die, and the upper die of the target forging die is controlled to press down to obtain the target aluminum alloy forging, the shape of which matches the target forging die.

[0119] It should be noted that the target forging die is also a final forming die. The shape of the target aluminum alloy forging is matched with the target forging die, and the resulting target aluminum alloy forging is also a final product. The microstructure of this final product is characterized by the disappearance of the original semi-solid spherical solid phase grains, which are replaced by fine, uniform, and continuous refined grains.

[0120] In this embodiment, the electronic device cools and solidifies the deformed aluminum alloy forging, which is a third aluminum alloy billet obtained after the deformed aluminum alloy forging in a solid-liquid coexistence state enters a fully solid state. Subsequently, the electronic device controls the induction heating device to precisely heat the third aluminum alloy billet to a preset solid phase temperature range (this temperature is lower than the solidus temperature) to obtain a fourth aluminum alloy billet. Then, the electronic device drives the forming device to place the fourth aluminum alloy billet in the target forging mold, and controls the upper die of the target forging mold to apply a high load to perform large strain plastic deformation to obtain the target aluminum alloy forging.

[0121] It should be noted that, during this process, because the third aluminum alloy billet is in a fully solid state and undergoes intense extrusion, the electronic device utilizes the powerful forging stress to induce dislocation climb and dynamic recovery within the metal. Through a strain-induced recrystallization mechanism, the coarse equiaxed crystals generated during the semi-solid thixotropic preforming process due to high-temperature holding are forcibly broken and recrystallized, thereby significantly refining the grain size. Simultaneously, the electronic device applies multi-directional shear stress to the interior of the fourth aluminum alloy billet by controlling the extrusion path of the target forging die cavity. This stress field mechanically breaks up the localized liquid phase aggregation zones (i.e., segregation zones) that may form during the semi-solid thixotropic preforming process, driving the originally aggregated second-phase particles to relocate within the aluminum matrix and become dispersed and uniformly distributed. This completely eliminates the microstructure segregation phenomenon from a physical perspective, ultimately obtaining a target aluminum alloy forging with a refined microstructure and uniform composition. Therefore, this method achieves the unity of precise filling of complex geometries and excellent mechanical properties through the coupling of "semi-solid shape control" and "all-solid property control". This results in aluminum alloy forgings that are not only internally dense and defect-free, but also have fine and continuous grains. The tensile strength and plasticity are significantly improved compared to single-step processes, truly bringing out the high-performance potential of spray-formed aluminum alloy materials.

[0122] In this embodiment, the technical solution described in steps 201-203 involves heating the spray-formed aluminum alloy billet to a semi-solid temperature range, so that the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 50% to 65%, forming a semi-solid slurry composed of solid phase spherical particles coated with a uniform liquid film; placing the semi-solid slurry in the lower mold of the forming mold, and using a segmented pressure control process to control the upper mold of the forming mold to press down, so that the semi-solid slurry completes defect repair and forming within the closed cavity, obtaining a deformed aluminum alloy forging; cooling the deformed aluminum alloy forging to obtain a third aluminum alloy billet; heating the third aluminum alloy billet again to reach a preset solid phase temperature range, obtaining a fourth aluminum alloy billet; placing the fourth aluminum alloy billet in the lower mold of the target forging mold, and controlling the upper mold of the target forging mold to press down, obtaining the target aluminum alloy forging. This method, through a composite forming approach combining "semi-solid thixotropic preforming" and "solid-state precision forging," achieves a deep coupling between complex geometric filling and microstructural enhancement. By employing a "shape-first, property-second" strategy, it overcomes the limitations of forming complex ribbed and deep-cavity structural components, enabling complex aluminum alloy parts to achieve a fine, continuous grain structure while maintaining macroscopic dimensional accuracy. Compared to the single-step process of steps 101-103 described above, this method not only ensures internal density and defect-free properties but also significantly improves tensile strength and plasticity, fully exploring and leveraging the high-performance potential of spray-formed aluminum alloys in core load-bearing components for aerospace applications.

[0123] The semi-solid thixotropic forming system for spray-formed aluminum alloy billets provided in the embodiments of this application will be described below. The semi-solid thixotropic forming system for spray-formed aluminum alloy billets described below can be referred to in correspondence with the semi-solid thixotropic forming method for spray-formed aluminum alloy billets described above.

[0124] Figure 8 This is a schematic diagram of the semi-solid thixotropic forming system for spray-formed aluminum alloy billets provided in an embodiment of this application. Figure 8 As shown, the system includes: a heating module 801, a pressing deformation module 802, and a target deformation module 803.

[0125] Heating module 801 is used to heat the spray-formed aluminum alloy billet to the semi-solid temperature zone, so that the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 30% to 70%, forming a semi-solid slurry composed of solid phase spherical particles coated with a uniform liquid film.

[0126] The pressing and deformation module 802 is used to place the semi-solid slurry in the lower mold of the forming mold and use a segmented pressure control process to control the upper mold of the forming mold to press down, so that the semi-solid slurry completes defect repair and forming in the closed cavity, and obtains the deformed aluminum alloy forging.

[0127] The target deformation module 803 is used to cool and solidify the deformed aluminum alloy forging to obtain the target aluminum alloy forging.

[0128] Optionally, the heating module 801 is specifically used to rapidly heat the spray-formed aluminum alloy billet from room temperature to 50°C below the solidus temperature at a heating rate of ≥10°C / s in the first stage to obtain a first aluminum alloy billet; in the second stage, heat the first aluminum alloy billet to the solidus temperature and hold it at that temperature so that the temperature difference between the center and the surface of the first aluminum alloy billet is ≤10°C to obtain a second aluminum alloy billet; in the third stage, heat the second aluminum alloy billet from the solidus temperature to a target semi-solid temperature within the semi-solid temperature range to obtain the semi-solid slurry, wherein the target semi-solid temperature corresponds to a liquid phase fraction of 30% to 70%.

[0129] Optionally, the pressing deformation module 802 is specifically used to control the upper die of the forming mold to press down using the first pressure in the first pressure section, utilizing the superplastic flow characteristics of the liquid phase in the semi-solid slurry to remove the internal gas of the semi-solid slurry, thereby obtaining a prototype of the target aluminum alloy forging; using the second pressure in the second pressure section, the upper die of the forming mold is controlled to continue pressing down, utilizing the capillary effect to drive the liquid phase in the semi-solid slurry to penetrate into the micropores inside the semi-solid slurry, thereby filling and repairing the porosity and interlayer non-fusion defects in the prototype of the target aluminum alloy forging, thereby obtaining a repaired part of the target aluminum alloy forging; using the third pressure in the third pressure section, the upper die of the forming mold is controlled to continue pressing down, thereby forcibly plastically deforming the repaired part of the target aluminum alloy forging to obtain the deformed aluminum alloy forging.

[0130] Optionally, the pressure in the first pressure section is 20% to 49% of the rated total pressure. Under the action of the first pressure, the semi-solid slurry undergoes grain boundary sliding and rotation, and initially fills the deep ribs and narrow grooves of the forming mold.

[0131] Optionally, the pressure in the second pressure section is 50% to 79% of the rated total pressure, and the pressure holding time is 3 to 10 seconds. The pressure gradient established by the second pressure is used to coordinate with the capillary pressure generated by the surface tension of the liquid phase in the semi-solid slurry, guiding the liquid phase in the semi-solid slurry to converge towards the micron-level loose and interlayer unfused defects and to undergo metallurgical bonding.

[0132] Optionally, the pressure in the third pressure section is 80% to 100% of the rated total pressure, used to force plastic deformation of the repair part of the target aluminum alloy forging.

[0133] Optionally, in the segmented pressure control process, the downward pressing speed of the upper die of the forming mold is controlled by a variable speed. The variable speed control includes: in the first pressure section, controlling the upper die of the forming mold to press down at a first speed, so that the semi-solid slurry is in a superplastic flow state; in the second pressure section, controlling the upper die of the forming mold to press down at a second speed, the second speed being less than the first speed, and increasing the holding time, so as to utilize the capillary effect to allow the liquid phase in the semi-solid slurry to fully penetrate into the porous and interlayer unfused defects in the prototype of the target aluminum alloy forging.

[0134] Optionally, the pressing deformation module 802 is also used to control the upper mold of the forming mold to continue pressing down before entering the third pressure section, based on the displacement of the upper mold of the forming mold or a set time threshold, by cyclically using the pressure in the first pressure section and the pressure in the second pressure section, so that the semi-solid slurry can complete the defect repair in the closed cavity.

[0135] Optionally, the target deformation module 803 is specifically used to maintain the pressure of the upper die of the forming mold at the pressure in the third pressure segment while keeping the forming mold in a closed state, and to cool the deformed aluminum alloy forging after a preset time period to obtain the target aluminum alloy forging.

[0136] Optionally, the target deformation module 803 is used to cool and solidify the deformed aluminum alloy forging when the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 50% to 65% to obtain a target aluminum alloy forging. The method includes: cooling the deformed aluminum alloy forging to obtain a third aluminum alloy billet; reheating the third aluminum alloy billet to reach a preset solid phase temperature range to obtain a fourth aluminum alloy billet; placing the fourth aluminum alloy billet in the lower die of the target forging die and controlling the upper die of the target forging die to press down to obtain the target aluminum alloy forging, wherein the shape of the target aluminum alloy forging matches the target forging die.

[0137] Figure 9 This is a schematic diagram of the structure of the electronic device provided in an embodiment of this application. For example... Figure 9 As shown, the electronic device may include a processor 910, a communications interface 920, a memory 930, and a communication bus 940, wherein the processor 910, the communications interface 920, and the memory 930 communicate with each other via the communication bus 940. The processor 910 can call logic instructions in the memory 930 to execute a semi-solid thixoforming method for spray-formed aluminum alloy blanks.

[0138] Furthermore, the logical instructions in the aforementioned memory 930 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0139] On the other hand, embodiments of this application also provide a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer is able to execute the semi-solid thixotropic forming method for spray-formed aluminum alloy billets provided by the above methods.

[0140] In another aspect, embodiments of this application also provide a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the semi-solid thixotropic forming method for spray-formed aluminum alloy billets provided by the methods described above.

[0141] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0142] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the prior art, can be embodied in the form of software products. These computer software products can be stored in computer-readable storage media, such as ROM / RAM, magnetic disks, optical disks, etc., and include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of various embodiments or certain parts of embodiments.

[0143] 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 semi-solid thixotropic forming method for spray-formed aluminum alloy billets, characterized in that, include: The spray-formed aluminum alloy billet is heated to the semi-solid temperature zone, so that the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 30% to 70%, forming a semi-solid slurry composed of solid phase spherical particles coated with a uniform liquid film. The semi-solid slurry is placed in the lower mold of the forming mold, and the upper mold of the forming mold is pressed down using a segmented pressure control process, so that the semi-solid slurry completes defect repair and forming in the closed cavity to obtain the deformed aluminum alloy forging. The deformed aluminum alloy forging is cooled and solidified to obtain the target aluminum alloy forging.

2. The semi-solid thixotropic forming method for spray-formed aluminum alloy billets according to claim 1, characterized in that, The segmented pressure control process controls the downward pressure of the upper die of the forming mold, allowing the semi-solid slurry to complete defect repair and forming within a closed cavity, resulting in a deformed aluminum alloy forging, including: Using the first pressure in the first pressure section, the upper die of the forming mold is pressed down. The superplastic flow characteristics of the liquid phase in the semi-solid slurry are used to remove the internal gas of the semi-solid slurry, thereby obtaining the prototype of the target aluminum alloy forging. Using the second pressure in the second pressure section, the upper mold of the forming mold is controlled to continue to press down. The capillary effect is used to drive the liquid phase in the semi-solid slurry to penetrate into the micropores inside the semi-solid slurry, thereby filling and repairing the porosity and interlayer non-fusion defects in the prototype of the target aluminum alloy forging, and obtaining the repaired part of the target aluminum alloy forging. Using the third pressure in the third pressure section, the upper die of the forming mold is controlled to continue pressing down, and the repair part of the target aluminum alloy forging is subjected to forced plastic deformation to obtain the deformed aluminum alloy forging.

3. The semi-solid thixotropic forming method for spray-formed aluminum alloy billets according to claim 1 or 2, characterized in that, The process of heating the spray-formed aluminum alloy billet to a semi-solid temperature range, so that the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 30% to 70%, forming a semi-solid slurry composed of solid-phase spherical particles coated with a uniform liquid film, includes: In the first stage, the spray-formed aluminum alloy billet is rapidly heated from room temperature to 50°C below the solidus temperature at a heating rate of ≥10°C / s to obtain the first aluminum alloy billet. In the second stage, the first aluminum alloy billet is heated to the solidus temperature and held at that temperature, so that the temperature difference between the center and the surface of the first aluminum alloy billet is ≤10℃, thus obtaining the second aluminum alloy billet. In the third stage, the second aluminum alloy billet is heated from the solidus temperature to the target semi-solid temperature within the semi-solid temperature range to obtain the semi-solid slurry, wherein the target semi-solid temperature corresponds to a liquid phase fraction of 30% to 70%.

4. The semi-solid thixotropic forming method for spray-formed aluminum alloy billets according to claim 2, characterized in that, The pressure in the first pressure section is 20% to 49% of the rated total pressure. Under the action of the first pressure, the semi-solid slurry undergoes grain boundary sliding and rotation, and initially fills the deep ribs and narrow grooves of the forming mold.

5. The semi-solid thixotropic forming method for spray-formed aluminum alloy billets according to claim 2, characterized in that, The pressure in the second pressure section is 50% to 79% of the rated total pressure, and the pressure holding time is 3 to 10 seconds. The pressure gradient established by the second pressure is used to coordinate with the capillary pressure generated by the surface tension of the liquid phase in the semi-solid slurry, and guide the liquid phase in the semi-solid slurry to converge towards the micron-level loose and interlayer unfused defects and to undergo metallurgical bonding.

6. The semi-solid thixotropic forming method for spray-formed aluminum alloy billets according to claim 2, characterized in that, The pressure in the third pressure section is 80% to 100% of the rated total pressure, and is used to force plastic deformation of the repair part of the target aluminum alloy forging.

7. The semi-solid thixotropic forming method for spray-formed aluminum alloy billets according to claim 2, characterized in that, In the segmented pressure control process, the downward pressing speed of the upper die of the forming mold is controlled by a variable speed control, which includes: In the first pressure section, the upper mold of the forming mold is controlled to press down at a first speed, so that the semi-solid slurry is in a superplastic flow state. In the second pressure section, the upper die of the forming mold is controlled to press down at a second speed, which is less than the first speed, and the holding time is increased. The capillary effect is used to allow the liquid phase in the semi-solid slurry to fully penetrate into the porous and interlayer unfused defects in the prototype of the target aluminum alloy forging.

8. The semi-solid thixotropic forming method for spray-formed aluminum alloy billets according to claim 1, characterized in that, When the internal liquid phase fraction of the spray-formed aluminum alloy billet reaches 50% to 65%, the deformed aluminum alloy forging is cooled and solidified to obtain the target aluminum alloy forging, comprising: The deformed aluminum alloy forging is cooled to obtain a third aluminum alloy billet; The third aluminum alloy billet is heated again until the current heating temperature reaches the preset solid phase temperature range to obtain the fourth aluminum alloy billet. The fourth aluminum alloy billet is placed in the lower die of the target forging die, and the upper die of the target forging die is controlled to press down to obtain the target aluminum alloy forging. The shape of the target aluminum alloy forging matches the target forging die.

9. The semi-solid thixotropic forming method for spray-formed aluminum alloy billets according to claim 2, characterized in that, The method further includes: Before entering the third pressure section, the pressure in the first pressure section and the pressure in the second pressure section are used cyclically according to the displacement of the upper mold of the forming mold or the set time threshold to control the upper mold of the forming mold to continue to press down, so that the semi-solid slurry completes defect repair in the closed cavity.

10. The semi-solid thixotropic forming method for spray-formed aluminum alloy billets according to claim 2, characterized in that, The process of cooling and solidifying the deformed aluminum alloy forging to obtain the target aluminum alloy forging includes: While keeping the forming mold in a closed state, the pressure of the upper die of the forming mold is maintained at the pressure in the third pressure segment, and after a preset time, the deformed aluminum alloy forging is cooled to obtain the target aluminum alloy forging.

Images