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The heating rates and forming temperatures during the hot forming process of titanium alloys cause significant differences in phase transformation, grain size, and dislocation evolution. The formability and service performance of titanium alloy formed components are affected by these factors. This study investigated the hot flow behaviors of Ti-6Al-4V at temperatures ranging from 800 to 900 °C and heating rates ranging from 0.1 to 10 °C/s. These were tested via Gleeble hot tensile experiments, and the grain size and phase evolution were quantitatively characterized via EBSD and XRD. The results suggest that a higher heating rate decreases the β-phase transformation and dislocation density and inhibits grain coarsening, leading to better formability. The heating rate was introduced into the viscoplastic constitutive model for the first time to achieve accurate predictions of the microstructure and hot flow behavior under different heating rates. The prediction accuracy of the hot flow behavior and phase volume fraction reaches 92.93% and 94.97%. The current-assisted hot stamping experiments and finite element (FE) simulations of Ti-6Al-4V irregular cross-section components were carried out at temperatures of 800 and 900 °C and at heating rates of 1 and 3 °C/s. The results show that the rapidly heated formed components exhibit better thickness uniformity and yield strength. The FE simulation guided by the optimized constitutive model has achieved a 96.96% and 92.76% prediction accuracy for the thickness distribution and β-phase volume fraction, respectively.

The deformation mechanism during the hot compression of PM nickel-based superalloy FGH99 and its micro-structural evolution, especially the evolution of γ’ phases, are the key factors affecting the final molding quality of aero-engine hot forged turbine disks. In this study, a new constitutive model of viscoplasticity with micro-structures as physical internal parameters were developed to simulate the hot compression behavior of FGH99 by incorporating the strengthening effect of the γ’ phase. The mechanical behavior of high-temperature (>1000 K) compressive deformation of typical superalloys under a wide strain rate (0.001~1 s−1) is investigated using the Gleeble thermal-force dynamic simulation tester. The micro-structure after the hot deformation was characterized using EBSD and TEM. Work hardening as well as dynamic softening were observed in the hot compression tests. Based on the mechanical responses and micro-structural features, the model considered the coupled effects of dislocation density, DRX, and γ’ phase during hot flow. The model is programmed into a user subroutine based on the Fortran language and called in the simulation of the DEFORM-3D V6.1 software, thus realizing the multiscale predictive simulation of FGH99 alloy by combining macroscopic deformation and micro-structural evolution. The established viscoplastic constitutive model shows a peak discrepancy of 10.05% between its predicted hot flow stresses and the experimental values. For the average grain size of FGH99, predictions exhibit an error below 7.20%. These results demonstrate the high accuracy of the viscoplastic constitutive model developed in this study.

The heat transfer coefficient, including interfacial heat transfer coefficient (IHTC) and convective heat transfer coefficient (CHTC), plays a pivotal role in the thermal dynamics of hot gas forming processes. This parameter can determine the temperature field, thereby affecting the deformation and mechanical properties of the material to improve productivity. In this paper, we present an innovative experimental apparatus designed to measure the temperature evolutions of the aluminum specimen and the die during the hot gas forming processes. This apparatus is capable of simultaneously measuring IHTC and CHTC. Using the inverse finite element method, the simulated temperature histories are matched with empirical data and the best-fit values are adopted as indicative of IHTC and CHTC. This study identified the effects of contact pressure and die temperature on IHTC, as well as the impact of gas pressure on CHTC. In addition, a predictive model was developed to forecast the IHTC and CHTC at varying contact pressures and die temperatures with a prediction accuracy surpassing 0.95. By leveraging the predictive model presented in this paper, users can modulate contact pressure and die temperature based on specific production needs to achieve a targeted temperature profile. This method offers enhanced precision in managing the temperature field of the workpiece during hot gas forming experiments, thereby refining the temperature distribution. Moreover, it optimizes the formability and microstructural attributes of the material, ultimately leading to improved mechanical characteristics.

In this paper, the current-assisted hot stamping process of high-temperature titanium alloy is used to prevent the limited formability caused by the temperature loss during the transfer. The forming experiment and simulation of the regular cross-section component of the TA32 high-temperature titanium alloy missile shell were carried out at 780–940 ℃. First, the effect of forming temperature and heating rate on the forming accuracy, microstructure evolution, and component strength of TA32 were studied. Second, a plane stress visco-plastic model of TA32 was successfully implemented into the finite element (FE) model using a VUMAT subroutine, combined with the traditional FE; the difference in simulation accuracy of TA32 forming components under two FE analyses was analyzed. The results show that the increased forming temperature and slow heating rate can promote the β phase transition and reduce the flow stress and dimensional deviation of the components. However, the decreasing hardening due to the low dislocation density leads to a decrease in thickness uniformity. Through comparison, it is found that the subroutine FE simulation results have better prediction accuracy than that of the traditional FE simulation, and the simulation accuracy of the average thickness distributions and dimensional deviation is improved by 25.1% and 43.7%, respectively. The results of this research provide guidance on matching forming temperature and heating rate for the TA32 components while ensuring high forming an accuracy and efficient production cycle.

This paper presents a systematic study of heating effects on the hot deformation and microstructure of dual-phase titanium alloy Ti-6Al-4V (TC4) under hot forming conditions. Firstly, hot flow behaviors of TC4 were characterized by conducting tensile tests at different heating temperatures ranging from 850 °C to 950 °C and heating rates ranging from 1 to 100 °C/s. Microstructure analysis, including phase and grain size, was carried out under the different heating conditions using SEM and EBSD. The results showed that when the heating temperature was lower than 900 °C, a lower heating rate could promote a larger degree of phase transformation from α to β, thus reducing the flow stress and improving the ductility. When the temperature reached 950 °C, a large heating rate effectively inhibited the grain growth and enhanced the formability. Subsequently, according to the mechanism of phase transformation during heating, a phenomenological phase model was established to predict the evolution of the phase volume fraction at different heating parameters with an error of 5.17%. Finally, a specific resistance heating device incorporated with an air-cooling set-up was designed and manufactured to deform TC4 at different heating parameters to determine its post-form strength. Particularly, the yield strength at the temperature range from 800 °C to 900 °C and the heating rate range from 30 to 100 °C/s were obtained. The results showed that the yield strength generally increased with the increase of heating temperature and the decrease of heating rate, which was believed to be dominated by the phase transformation.

The isothermal hot forming of high-elasticity titanium alloy thin-walled components often suffers from significant elastic loss. This study investigates the novel Ti–35Nb–2Zr–0.3O (Ti3523) high-elasticity titanium alloy, focusing on the effects of rapid resistance heating (RRH) compared to traditional muffle furnace heating (MFH) on its microstructure and mechanical properties via EBSD and tensile tests. The results show that RRH at a high heating rate (~45 °C/s) effectively suppresses grain coarsening and minimizes dislocation annihilation. Following air cooling, the yield strength of the alloy decreased to 503.01 MPa for RRH-treated specimens, while 405.49 MPa for MFH-treated specimens compared to the original cold-rolled sheet with a yield strength of 754.25 MPa. Additionally, RRH promoted a higher martensitic α′′ transition, leading to lower elastic modulus (40.62 GPa). After aging treatment, the RRH-treated specimens exhibited precipitation of a high-strength α phase, leading to significant improvement of yield strength (755.63 MPa) and elastic modulus (70.39 GPa). The elastic performance of RRH-treated specimens ( Ur = 4.056 MPa) was better than that of the MFH-treated specimens ( Ur = 3.333 MPa) and close to the performance of the original sheet ( Ur = 4.577 MPa). With the identical heating method (RRH), higher heating rates can preserve the high elasticity of the original sheet. Building upon these findings, the hot forming process of the Ti3523 alloy was further explored. The results revealed that dynamic recrystallization process occurs more completely in the alloy after forming and aging under the RRH process, leading to a 70.72% increase in resilience modulus compared to the original cold-rolled sheet. Due to the dynamic recrystallization, the dislocation density decreased from 6.94×10 14 /m 2 to 6.63×10 14 /m 2 and the proportion of dynamically recrystallized grains increased from 28% to 48.1% after aging treatment. This rapid heating and high-temperature forming method offers a promising technical route for manufacturing advanced aerospace components.

Background Tracheoesophageal fistula (TEF) is a rare but life-threatening complication after esophagectomy. A new gastrointestinal occluder device provides treatment for TEF patients. However, TEF-related pneumonia and respiratory failure increase the difficulty of anesthesia management, especially in airway management. Case presentation A 64-year-old man with thoracic esophageal cancer underwent esophagectomy and gastric tube reconstruction one year ago. The patient presented with recurrent cough and sputum after surgery. Gastroscopy revealed a fistula between the esophagogastric anastomotic site and membrane of the trachea. Therefore, the patient received implantation of a new gastrointestinal occluder device under gastroscopy combined with tracheoscopy. Airway management under general anesthesia was discussed with an interdisciplinary decision, and cuffed endotracheal tube with an inner diameter of 5.5 mm was chosen. This airway management ensured adequate oxygenation during the operation and provided sufficient space for the operation of the tracheoscope in the trachea. Finally, the TEF disappeared after the operation, and the patient was administered an oral diet on the first postoperative day. Conclusions The implantation of a new gastrointestinal occluder device under gastroscopy combined with tracheoscopy provides a new treatment for TEF patients. This case report suggests that it is important to select an endotracheal tube with an appropriate inner diameter that can not only meet the requirements of ventilation but also does not affect the operation of tracheoscopy in the trachea.

In the North China Plain, it is a matter of urgency to explore the feasibility of using biodegradable film to replace polyethylene film. A field experiment was conducted by covering soils with polyethylene white film, biodegradable white film, biodegradable black film, while the control remained uncovered. This study analysed the effects of using different film types on summer maize dry matter accumulation and transfer, grain yield and yield components during the 2016 and 2017 summer maize growing seasons. Results showed that, for both growing seasons, compared with non-mulching, dry matter translocation, dry matter transfer efficiency of vegetative organs and grain yield for plants following polyethylene white film and biodegradable white film treatments were always lower. However, dry matter accumulation, dry matter translocation, dry matter transfer efficiency, grain yield, and the contribution of dry matter translocation to grain yield before flowering in biodegradable black film treatments significantly increased by 21.0, 33.3, 21.4, 12.6, and 18.5%, respectively. Only the black biodegradable film could increase grain yield as determined by the 1000 kernel mass. Results indicate that black biodegradable films are a viable alternative to polyethylene film in summer maize production in the North China Plain.

Precision beam polarization measurements based on Compton polarimeters are essential for the physics program of future high-energy colliders. In order to prepare for these and to extend the scope of physics measurements of the BESIII experiment at the BEPCII, a diagnostic of electron beam transverse polarization at BEPCII is of interest. The design and status report of the commissioning, until July 2025, of this device is reported in this paper. We report unambiguous observation of Compton interaction, discuss current limitations of the experimental setup and draw prospects for improvements and actual measurement of electron beam polarization in the near future.