Search Results (470)

Energy-intensive foundries require methods to explore trade-offs among delivery performance, production horizon, electricity use, and cost when industrial data are incomplete. This paper presents an offline, process-level digital twin case study for the melting and casting area of a Danish cast-iron foundry. A multi-agent simulation represents production orders, enterprise resource planning and manufacturing execution system functions, induction furnaces, holding furnaces, crane-based transfer of molten metal, vertical moulding lines, the operating calendar, and electricity cost accounting for the induction furnaces. The model is assessed through boundary definition, assumption registration, implementation checks, material flow plausibility, a diagnostic comparison of furnace temperature, controlled scenario experiments, and local sensitivity analysis. These activities support internal consistency and bounded interpretation but do not constitute independent operational validation of the full production system. In the simulated 200-order monthly case, First-Come-First-Served and Earliest Deadline First complete the same 288,620 pieces and 5482.00 t. Earliest Deadline First increases the simulated on-time completion rate from 87.5% to 100%, while makespan, model-estimated electricity use by induction furnaces, and model-estimated electricity cost increase by 7.52%, 0.58%, and 3.42%, respectively. The case indicates that deadline-oriented sequencing may improve delivery performance but lead to a longer production horizon and higher energy use and cost within the defined model boundary. The contribution is an auditable foundry-specific modelling workflow that links heterogeneous data conditions to modelling choices, supporting evidence, and interpretation limits. The model is therefore intended for preliminary offline scenario exploration rather than validated operational decision support. Full article

The geometric morphology and dynamic evolution of the molten pool are key indicators of heat input, metal transfer, and solidification behavior during welding, making them critical for quality monitoring and process control. To address the challenges of molten pool image segmentation under complex conditions, including strong arc interference, blurred boundaries, small foreground regions, and significant shape variations, a MIG welding-based visual acquisition system is established to construct a multi-condition dataset. Based on this dataset, an efficient boundary-guided dual-branch network, WPSeg-Net, is proposed. The network employs ResNet-34 as the encoder, integrates a lightweight Transformer module for global context modeling, and adopts BiFPN for multi-scale feature fusion. A region branch and a boundary branch with a mutual guidance mechanism are further designed to improve segmentation accuracy and boundary refinement. Experimental results demonstrate that WPSeg-Net achieves an IoU of 92.83% and a Dice score of 96.28%, improving by 0.98% and 0.58% over DeepLabV3+, respectively. Meanwhile, the proposed method reduces the parameter size from 22.43 MB to 21.78 MB and decreases FLOPs from 62.25 G to 31.90 G, achieving a better balance between segmentation performance and computational efficiency. Full article

Relatively low-cost titanium carbide (TiC) materials and metal matrix composites (MMC) are proposed for waste-to-hydrogen conversion. Two types of steels are used as bases prepared from EN 10088 flat products, namely X2CrTi12 (1.4512, AISI 409) and X5CrNi18-10 (1.4301, AISI 304). TiC is mixed with TRIBALOY^® T-800 alloy in powder form and applied via laser-directed energy deposition (DED-LB) over the substrates. For the powder mixture, Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) are performed. The raw materials are investigated for the processes that occur in them under heating. After the solidification of the molten mixture, grinding and polishing are performed to achieve a thin layer. The studies of the obtained MMC include interface zone assessment, hardness and Young’s modulus distribution, microstructural analysis, and visual defect evaluation. Advanced sensors for acoustic emission (AE) and Electrical Contact Resistance (ECR) provided characterization together with micro-scratch testing. The use of photoluminescence spectroscopy is proposed for the new composite materials. The electron transfer pathway can be studied with time-resolved spectroscopy. Renewable energy production by breaking down waste into hydrogen-rich syngas can be achieved through pyrolysis, followed by steam reforming and purification. The obtained novel materials show promising application solutions with increased durability, corrosion, and wear resistance. Full article

Aluminum/magnesium (Al/Mg) hybrid structures are promising candidates for lightweight engineering, but reliable joining is still limited by brittle intermetallic compounds (IMCs), oxide films, pores, cracks, and corrosion-related degradation. This review summarizes recent advances in Al/Mg dissimilar-metal joining, including solid-state welding, fusion welding, brazing, resistance-based joining, and mechanical joining. Emphasis is placed on process characteristics, interfacial reactions, defect formation, mechanical properties, service reliability, and simulation-assisted process understanding. The reviewed studies indicate that joint reliability cannot be interpreted solely from IMC thickness; phase type, continuity, spatial distribution, interfacial morphology, and involvement in the fracture path are also critical. Solid-state and high-speed impact processes can restrict continuous Al–Mg reaction layers by reducing thermal exposure and promoting plastic contact, whereas fusion-based processes provide greater manufacturing flexibility but require stricter control of molten-pool behavior, Mg evaporation, porosity, and interlayer stability. Recent numerical simulations and data-driven studies are further discussed as tools for mechanism-guided parameter design. This review provides an integrated comparison of joining routes and highlights future needs for standardized testing, fatigue and corrosion evaluation, thermal-cycling assessment, coupled service-performance analysis, and process selection for engineering applications. Full article

MXenes, a rapidly expanding family of two-dimensional transition-metal carbides and nitrides, are increasingly viewed as strong candidates for defense-oriented multifunctional systems because they combine metallic conductivity, surface tunability, mechanical flexibility, and solution processability within a lightweight platform. Unlike conventional metals, ceramics, and semiconductors, which usually optimize one or two parameters at the expense of density, brittleness, or integration compatibility, MXenes offer a rare opportunity to coordinate electromagnetic, mechanical, thermal, and sensing functions within one material family. Different from existing reviews that focus on laboratory-level record performance or single-function optimization, this review presents an innovative deployment-oriented perspective and fills the research gap of systematic military-oriented evaluation for MXenes. In this review, we examine MXenes from a deployment-oriented perspective rather than through isolated record values. We first summarize their formation chemistry and major synthesis routes, including HF and in-situ HF etching, bifluoride and alkaline methods, molten-salt strategies, electrochemical approaches, and precursor-free chemical vapor deposition. We then discuss the principal levers of property regulation, focusing on composition design, surface-termination control, and heterostructure engineering, and show how these strategies shape the performance envelopes relevant to shielding, stealth, impact response, energy storage, and sensing. This review constructs a full-chain analytical framework from synthesis, property regulation to military application and deployment challenges for the first time. Finally, we identify the main barriers to translation, especially manufacturing inconsistency, termination heterogeneity, oxidation and interfacial degradation, and limited application-level validation, and outline the most realistic paths toward deployable defense technologies. Full article

Activated Tungsten Inert Gas (ATIG) welding employs an activating flux to increase penetration and improve productivity compared with the conventional Tungsten Inert Gas (TIG) process. Conventional fluxes typically consist of metallic oxides dispersed in alcohol- or acetone-based solvents. In this study, a novel flux composed of SiO₂ and TiO₂ nanoparticles suspended in a sodium-silicate solvent was used for welding Inconel 718. The proposed flux achieved full penetration of a 7 mm thick plate at 160 A DCEN using 60° and 90° electrode tip angles, without visible distortion or defects in the examined cross-sections. Microstructural characterization revealed notable changes in the content, morphology, and size of Nb-rich interdendritic constituents consistent with Laves phase formation compared with welds produced without flux. ATIG specimens contained a lower amount of these brittle intermetallic constituents, which exhibited a less branched and more coagulated morphology despite the lower cooling rate. As a result, a greater fraction of alloying elements remained available for dendrite reinforcement rather than being segregated into Nb-rich interdendritic regions, leading to higher weld-metal microhardness in the ATIG60 specimen than in TIG welds. These observations were attributed to enhanced weld-pool stirring caused by molten metal flow toward the weld center and downward through the weld pool, consistent with the reversal of Marangoni convection. Full article

Rare earth has been widely introduced in heat-resistant steel. However, excessive amounts of rare earth should be added due to the low yield rate, and the molten steel in the mold was highly reducible. Severe slag–metal interface reactions occurred when conventional mold fluxes were used. To restrain interfacial reactions during continuous casting of heat-resistant steel containing rare earth, a new method for designing mold flux was proposed, and different flux systems containing rare earth oxide were devised. The properties such as melting temperature, viscosity, and crystalline phase of the different mold fluxes were systematically investigated. Comparisons of properties between the new fluxes and the conventional mold fluxes were conducted. The results show that properties similar to those of the conventional mold flux could be obtained by adopting Li₂O and B₂O₃ as fluxing agents in the newly designed system. The new mold flux with high content of CaO and Al₂O₃ had approximate properties with the conventional mold flux. Cerium oxide could not separate out in the continuous cooling process. The main crystalline phase was LiAlO₂ in the new mold fluxes, which is different from the cuspidine (3CaO∙2SiO₂∙CaF₂) in the conventional mold flux. LiAlO₂ can be a potential substitute for cuspidine. It was entirely feasible to devise and develop a new mold flux containing rare earth with a high content of CaO and Al₂O₃ for rare earth steel continuous casting by further optimizing its properties. Full article

Crack defects are prone to occur during MAG overlay remanufacturing of TBM cutter rings, thereby affecting the repair quality and service reliability of the remanufactured layer. In this study, longitudinal alternating magnetic field (LAMF) stirring was introduced into the MAG overlay remanufacturing process of H13 steel cutter rings to regulate molten-pool behavior and suppress crack defects. A molten-pool-scale sequentially coupled thermo-fluid-electromagnetic model was developed to compare the relative changes in the temperature and velocity fields with and without LAMF under identical MAG process parameters, heat-source input, material properties, and boundary conditions. In the model, the effect of LAMF was introduced through a Lorentz-force source term acting on the electrically conductive molten metal. The simulation results show that LAMF promoted heat redistribution within the molten pool, smoothed the thermal transition near the rear region of the molten pool, and reduced local heat accumulation. Meanwhile, LAMF modified the molten-pool flow pattern by weakening excessive flow along the welding direction and enhancing transverse circulation and vortex-induced mixing. Comparative overlay remanufacturing experiments were then conducted using a self-built magnetic-field stirring platform. Penetrant testing, X-ray inspection, metallographic observation, and industrial CT reconstruction were combined to characterize surface cracks, internal defects, and post-solidification microstructure. Compared with the non-LAMF condition, the maximum internal crack length decreased from 29.41 mm to 20.30 mm, corresponding to a reduction of 30.98%, and the crack-defect volume fraction decreased from 0.93% to 0.28%, corresponding to a decrease of 0.65 percentage points. The combined simulation and characterization results indicate that Lorentz-force-driven electromagnetic stirring improves the thermal-fluid conditions near the solidification front, thereby effectively reducing the formation tendency of solidification-related crack defects during MAG overlay remanufacturing. Full article

A novel sodium-oxide-fluxed slag is applied in the aluminothermic reduction of manganese ore. The slag’s high Al₂O₃ solubility facilitates the recycling of Al₂O₃ through hydrometallurgical processes, where NaAlO₂ serves as a water-leachable compound. Aluminothermic reduction is gaining renewed interest as an alternative processing route for the circular economy. In addition, CO₂ emissions in aluminium production via the electrochemical Hall–Héroult process can be reduced if the process electricity is sourced from non-fossil fuels. The unique Na₂O-fluxed MnO₂ ore formulation includes a small quantity of carbon reductant to ensure rapid pre-reduction to MnO. This approach negates the need for a pre-roasting step. Feed mixture variations with different collector metal additions (Si, Cr, Cu) were made to improve alloy–slag separation efficiency. The collector metals may influence the chemistry of the slag. This work compares the phase chemistry of slags formed during aluminothermic reduction to equilibrium phase chemistries calculated for the Na₂O-SiO₂-Al₂O₃-MnO-CaO system. The slag phase morphology consists of distinct alumina-rich strands (1.5% to 2.1%) embedded within a Na₂O-SiO₂-Al₂O₃-MnO-CaO glass matrix. The alumina-rich strands appear molten, indicating that the processing temperatures were higher than their liquidus temperatures (1537 °C to 1655 °C), as high as 1921 °C and 2053 °C. These findings contribute to sustainable practices in the circular economy through the production of low-carbon ferro-manganese complex alloys. Full article

Intermittent tilting pouring is widely utilized in metal casting due to its operational simplicity and cost-effectiveness. However, this method faces challenges such as difficult manual tuning and inconsistency in achieving constant flow rates. Targeting pouring equipment at a high-purity metal smelting company, this study proposes a closed-surface flux calculation method based on the Gauss divergence theorem to determine molten metal volume at any given instant. A mathematical model for pouring processes involving ladles with non-cylindrical inner surfaces is established. Based on this model, pouring characteristics are analyzed. Through piecewise fitting, angular velocity functions for constant flow rate pouring are derived, which provides theoretical guidance for practical industrial operations. Full article

Volatilization of alloying elements during vacuum refining of high-Cr die steel can cause fume generation, resource loss and increased dust-collection burden. Here, D2 high-carbon high-chromium die steel was melted in a vacuum induction furnace and held at 15 Pa and 1600 °C for 60 min, while CO and CO₂ evolution was monitored online. The collected volatile matter and the used magnesia crucible were characterized by XRF, XRD, Micro-CT, SEM-EDS, and XPS. The volatile matter mainly consisted of Fe-Cr-Mn metallic solid-solution phases and nanoscale agglomerates with partial surface oxidation. XRF results showed that the collected metallic volatile matter contained 49.96 wt.% Mn, 32.58 wt.% Fe, and 13.23 wt.% Cr. The enrichment factors of Cr and Mn relative to Fe were calculated to be 2.78 and 3.91 × 10², respectively, indicating strong selective volatilization of Mn. Micro-CT revealed that the deposition layer was confined to the inner surface of the upper crucible, while the bulk MgO crucible remained dense. Thermodynamic calculations showed that at 10 Pa, the calculated volatilization amounts of Fe, Cr, and Mn reached 3.32 g, 1.05 g, and 0.31 g per 100 g of molten steel, respectively, whereas element volatilization was markedly suppressed when the pressure was increased. A vacuum level above 20 Pa is therefore proposed as a practical process window to reduce fume generation and alloy loss during vacuum processing of high-Cr die steels. Full article

Wire arc additive manufacturing (WAAM) has emerged as a promising technology for producing large-scale metal components due to its high deposition efficiency, low material cost, and design flexibility. However, the widespread industrial adoption of WAAM is hindered by challenges in geometric accuracy, process stability, and defect control, which are closely related to two critical aspects: trajectory planning and real-time weld seam tracking. This review provides a comprehensive and critical analysis of recent advances in both fields, with an emphasis on their interconnection rather than treating them as separate research streams. Unlike existing reviews that primarily summarize path planning algorithms or image processing techniques in isolation, this paper explicitly examines the integration challenges and synergistic potential between offline trajectory optimization and online vision-based monitoring. Key topics include adaptive path strategies for sharp corners and intersections, interlayer filling methods to mitigate heat accumulation and residual stress, as well as passive and active visual sensing technologies for molten pool characterization and defect detection. The review further identifies a persistent gap in closed-loop systems that combine real-time image feedback with dynamic path replanning. Based on the analysis of representative studies, current limitations are discussed and future research directions are proposed, including the development of digital twins, multi-modal data fusion, and reinforcement learning-based adaptive control. This review offers a distinct perspective aimed at advancing intelligent, high-precision WAAM systems for complex metal components. Full article

With the rapid development of clean and low-carbon energy systems, non-metallic pipelines have become increasingly important in urban gas distribution, water supply, and emerging energy-transport applications, including hydrogen service. As a critical joining technology that governs system integrity and long-term operational safety, electrofusion welding requires a comprehensive and mechanism-oriented understanding beyond empirical process control. In this study, a review is conducted on research published over the past decade in the field of electrofusion welding of non-metallic pipelines, with emphasis on fundamental technical issues including the formation and evolution of temperature fields, characteristics of the molten fusion zone and defect development, and thermo-mechanical coupling with residual stress generation. Based on a synthesis of the literature, the review clarifies the global research landscape, core research communities, and underlying knowledge structure. The results indicate a clear transition of the field from empirically driven parameter optimization toward a mechanism-based and process-controllable paradigm centered on temperature field evolution, fusion zone development, and thermo-mechanical behavior. Current research hotspots converge on HDPE material adaptability, welding process regulation, and the long-term reliability of welded joints. Building on these insights, future research directions are discussed, including mechanism-driven process design, intelligent defect identification based on multi-source data, and full-life reliability assessment under service conditions. This review provides a theoretical framework to support process optimization and engineering application of electrofusion welding in non-metallic pipeline systems. Full article

Alkaline and alkaline earth metal chloride salts are used in molten chloride salt fast reactors (MCFRs) and pyro–electrometallurgical (or –electrochemical) recovering of uranium and transuranic elements (PERUT) from spent nuclear fuel. Reprocessing of MCFR spent fuel with the PERUT process, after recovery of U and transuranic elements (Np, Pu, Am, Cm), results in a chloride salt solvent waste stream containing fission and activation product chlorides. Recycling the chloride salt solvent by separation of fission and light element activation products (FPs and LEAPs) is highly desired because of the low chloride loading in the available glass and ceramic waste forms. This paper reviews the status of chloride salt waste management, chloride salt recycling studies, and potential FP and LEAP chlorides sequestration approaches. The chloride salt solvent recycling studies are represented by chemical precipitation of rare earth (RE) fission product chlorides with carbonate, O₂ gas and phosphate in LiCl and eutectic LiCl-KCl salt solvent, which is then followed by separation of Cs and Sr with distillation or crystallization. More than 99% removal efficiencies are attained for RE FP chlorides, and distillation removes more than 99% of Sr and Ba from the salt solvent. Volatile species released from the operation of MCFRs need to be sequestered. Minor chlorides species, such as SnCl₃, FeCl₃, CrCl₃, and ZrCl_2, will be present in the waste stream, and the separation of these species will be required for salt solvent recycling. Bromine and iodine can form bromides and iodides with metal elements such as alkaline and alkaline earth metal elements, which behave chemically similarly to their chloride counterparts. The presence of these compounds in the salt solvent waste may complexify the recycling process, for which more experimental studies are required. Full article

The quality and integrity of aluminothermic rail welds are strongly governed by the thermal conditions involved during preheating, pouring and cooling stages of the process. In this study, a simplified numerical framework is presented, based on the finite volume method and implemented in the open-source software OpenFOAM^® version 7, to predict the heat transfer and solidification processes. Within this framework, the preheating stage is simulated by employing a heat flux profile derived from experimental measurements, while the mould filling stage is neglected under the assumption of instantaneous pouring of the molten metal. The steel–slag multiphase system is treated using the Volume of Fluid method, whereas melting and solidification are captured using the enthalpy-porosity approach on a fixed Eulerian grid. The numerical framework is validated for a rapid welding process with short preheating procedure, consistent with typical industrial practice for rail welding. The predicted temperature histories during the preheating stage show sufficiently good agreement with the experimental measurements. Subsequently, the cooling stage is validated for a molten metal temperature of 2200 $°\mathrm{C}$ (≈2473 K). The predicted width of the fusion zone is compared with experimental data, showing reasonably good agreement in the railhead region, while an underestimation is observed in the rail web and rail foot regions. Furthermore, a systematic parametric investigation is conducted by varying two key process parameters, namely the molten metal temperature examined at four distinct levels ranging from 1800 $°\mathrm{C}$ (≈2073 K) to 2400 $°\mathrm{C}$ (≈2673 K), and the active preheating duration, varied across six values ranging from 90 $\mathrm{s}$ (1.5 min)–390 $\mathrm{s}$ (6.5 min), in order to assess their influence on the cooling stage. The numerical results provide detailed insight into the temporal evolution of the thermal field and its influence on the formation and extent of the fusion zone and heat-affected zone. The results demonstrate that, despite simplifications, the model captures the dominant thermal phenomena of the process and offers a computationally efficient tool for parameter studies and process optimisation. Full article