The design of submerged arc welding (SAW) fluxes for marine and offshore applications has traditionally relied on trial-and-error methods, leading to inconsistent arc stability and slag detachability. This study aims to systematically design and characterize twenty-five SAW fluxes using a Design of Experiments (DoE) approach based on SiO 2 –TiO 2 –CaF 2 –BaO–MnO ternary diagrams, with fixed CaO content addition. Basicity index (BI = 2.1–4.6), density measurements, thermophysical analysis (Hot Disk TPS-2500S), X-ray diffraction (XRD), and Fourier Transform Infrared (FTIR) spectroscopy were used to evaluate the flux formulations. Based on the obtained results, the values of bulk densities found in the range of 1.40–1.54 g/cm 3 , thermal conductivity range from 0.34 to 0.52 W/m·K, specific heat capacity range from 0.902 to 1.192 MJ/m 3 ·K, and thermal diffusivity range from 0.202 to 0.351 mm 2 /s. XRD confirms the presence of fluorite (CaF 2 ), rutile (TiO 2 ), and MnO phases, with composition-dependent crystallinity influencing slag fluidity. FTIR shows complex silicate networks, hydroxyl groups and depolymerization with the amount of modifiers. The flux formulation approach provides a rational basis for designing SAW fluxes with desirable thermophysical properties.
The effect of Ce on inclusions, carbides, and solidification structures in Cr12MoV cold-work die steel was systematically investigated through high-temperature melting experiments, 3D electrolytic etching and thermodynamic calculations. The results showed that with increasing Ce content, inclusions evolved in the following sequence: Al2O3 + MnS -> CeAlO3 -> Ce2O2S. Ce addition significantly refined the inclusions and promoted a more dispersed distribution within the steel matrix. Optimal inclusion modification was achieved with the Ce addition of 75 ppm, which effectively minimized the equivalent diameter of inclusions to approximately 3 mu m and maintained an area fraction of around 0.05% throughout the ingot. Furthermore, although Ce addition did not alter the existing carbide types, which were identified as Cr-rich M7C3, Mo-rich MC, and fine Cr-rich M23C6, it effectively refined the morphology of the eutectic network carbides and reduced the prior austenite grain size. Quantitative analysis demonstrated that the optimal 75 ppm Ce treatment reduced the total carbide area fraction by nearly half, decreasing it from approximately 14-17% to 7-9%. By establishing the quantitative relationship between Ce content and microstructural refinement, this study provides a theoretical basis for optimizing rare earth treatments, offering valuable guidance for the industrial production of high-performance cold-work die steels and the broader application of rare earth elements in high-alloy steels.
In this study, a previously developed structural model for ternary silicate melts and glasses, which assumes that metallic oxides behave similarly in silicate melts, was used to calculate the thermodynamic properties and ternary phase diagrams of the SiO 2 -NiO-FeO-Cu 2 O-MgO system. The model allows calculation of ternary system properties using only data from binary subsystems, without requiring any ternary terms. The phase diagrams for the NiO-SiO 2 and Cu 2 O-SiO 2 systems were optimized using a binary structural model. The ternary structural model was then applied to calculate the phase diagrams for SiO 2 -FeO-NiO, SiO 2 -Cu 2 O-NiO, and SiO 2 -MgO-NiO. The results showed that the mixing free energies for the NiO-SiO 2 , Cu 2 O-SiO 2 , and FeO-SiO 2 binary systems are very similar, supporting the assumption of random mixing of metal cations in the silicate structure. The mixing free energy of liquid MgO-SiO 2 is much lower than that of binary NiO-SiO 2 . Nevertheless, the calculated SiO 2 -MgO-NiO phase diagram agreed with the experimental results.
Design of a new strategy for the precipitation of Fe 2 Nb Laves phases was applied to optimize the mechanical properties of Fe-0.2C-2Nb (wt.%) steel. The quantitative models between the microstructure parameters and mechanical properties were established to reveal aging characteristics and strengthening mechanism of Fe 2 Nb Laves phases. The research found that the Fe 2 Nb phases aged at 200 °C for 15 min can effectively pin the dislocations in the grain interior and make an outstanding contribution to strength. The yield strength of as-peak-aged sample can reach 592 MPa from 307 MPa of as-received sample, the ultimate tensile strength can reach 752 MPa from 452 MPa of as-received sample, the total elongation can reach 13.56% from 9.01% of as-received sample, and the product of strength and elongation can reach 10.20 GPa% from 4.07 GPa% of as-received sample.
Blast furnace (BF) process & imath;in large-sized integrated complex plants is dependent on various process aspects due to sensitive heat balance and thermodynamics requirements. Operational parameters such as hot blast pressure, permeability, hot blast temperature, top gas pressure and temperature, wall pressures and temperatures, ore-to-coke ratio, flame temperature, additional steam and oxygen injections, etc. are aimed to keep balanced without any sudden fluctuations, movement or interruptions by experience and heuristic approach. In this paper, hot blast flow of a BF is modeled using ANN (Artificial neural networks) by selecting input parameters and time-series based statistical ARIMA (Autoregressive integrated moving average) model is applied using the same data and input-output set to compare the predictions success using performance criterion, R2, RMSE and MAPE. Secondly, a fuzzy logic model is developed to support oxygen enrichment decisions and model evaluates metal temperature, combustion and system balance trends, and makes oxygen increase, decrease or hold decisions. The experiment output reveals that ANN is very accurate to track hot blast flow values and shows better performance than ARIMA and proposed fuzzy-driven expert system could identify oxygen enrichment actions as next step to have efficient and cost-effective operation. The primary scientific novelty of this work is threefold: (i) for the first time in the open literature, a tightly coupled architecture is presented in which a data-driven ANN predictor for hot blast flow feeds directly into a real-time fuzzy expert system for oxygen enrichment control, creating a closed-loop advisory pipeline; (ii) the hybrid system is benchmarked against a statistical ARIMA baseline using three independent performance metrics grounding the evaluation in real plant conditions rather than simulated data; and (iii) hierarchical Mamdani type fuzzy inference architecture with metallurgically subsystems. Decision distributions yield 54.1% "Hold", 37.8% "Decrease", and 8.1% "Increase", demonstrating that the model adopts safe and stable control approach.
The use of degradable magnesium alloys (DMAs) in the oil and gas industry has been on rise in the past 10 to 15 years. The most notable application of DMAs is hydraulic fracturing. All applications of DMAs have one thing in common which is to temporarily plug a flow path then corrode to reestablish flow without needing costly and time-consuming well intervention. This review paper provides a thorough guide for the use of DMAs for the oil and gas industry. It discusses hydraulic fracturing methods as well as other applications in the oil and gas industry that utilize DMAs. Several topics are also introduced, such as the effect of alloying elements, manufacturing methods, and methods to analyze the corrosion rate in the lab. Finally, the paper presents a list of DMAs that were collected from peer-reviewed journals summarizing their mechanical and corrosion properties.
Waste printed circuit boards (WPCBs) are rich in valuable metals but contain large amounts of non-metallic fractions, leading to high slag viscosity and high flux consumption when smelted alone. This study proposed a co-smelting approach for WPCBs with copper concentrate, leveraging existing oxygen-enriched copper smelting technology. The effects of CaO addition, oxygen concentration, and Fe/SiO 2 ratio on copper content in the slag were investigated through thermodynamic calculations and co-smelting experiments. The results showed that CaO enlarged the liquidus region and reduced slag viscosity, but excessive addition formed high-melting-point phases such as Ca 2 SiO 4 . An appropriate Fe/SiO 2 ratio reduced slag viscosity, but an excessively high ratio increased the liquidus temperature. With a WPCBs to copper concentrate mass ratio of 1:10, 4 wt.% CaO addition, 60% oxygen concentration, and an Fe/SiO 2 ratio of 1.4 in the slag, the copper content in the slag decreased to 0.52 wt.%, while the magnetite content reached 19.26 wt.%. Magnetite enrichment around matte particles, which formed a wrapping layer was identified as the main cause of mechanical copper entrainment. This study provides theoretical support for the industrial application of co-smelting WPCBs with copper concentrate.
High-entropy alloys (HEAs) have gained wide attention for their exceptional structural and functional properties derived from their unique multi-principal element compositions. This review provides a comprehensive overview of HEAs, covering fabrication methods, processing parameters, mechanical behavior, and potential applications. Unlike many previous reviews, this workplace particular emphasis on elemental selection strategies explaining how to choose suitable elements based on thermodynamic parameters, atomic characteristics, and phase stability calculations. Detailed discussions on the use of predictive tools such as CALPHAD and phase diagram plotting software are included to guide beginners in designing and optimizing new HEAs. This paper aims to serve as a fundamental reference for early researchers, simplifying the path from alloy design to fabrication and property evaluation.
This study proposes a hybrid experimental-thermodynamic approach to determine the solubility products of rare earth oxysulfides and establish phase equilibria in molten copper. By combining limited experimental data at 1473 K with thermodynamic modeling, we derived temperature-dependent solubility product expressions (1340–1500 K) for Y 2 O 3 , YS, Y 2 O 2 S, Ce 2 O 3 , CeS, and Ce 2 O 2 S. Thermodynamic analysis conclusively rules out the formation of Y 2 S 3 and Ce 2 S 3 . We systematically analyzed the formation criteria for RE 2 O 2 S, RES, and RE 2 O 3 phases in liquid copper and constructed Y/Ce–O–S equilibrium diagrams at 1373 K and 1473 K. These results can provide essential foundational data for copper metallurgy for rare earth additions.
Molten salt temperature serves as a critical parameter for assessing the electrolytic reaction state in rare earth molten salt processes, and its precise prediction is fundamental to optimizing process control. Addressing challenges such as flame and material disturbances during electrolysis, as well as the insufficient accuracy of existing prediction models under dynamic disturbances, this paper proposes an intelligent molten salt temperature prediction method. This method first employs a Gaussian mixture model and Kalman filter to establish a dual "spatial-temporal" interference suppression mechanism, filtering out flame and material interference while smoothing temporal noise. It then integrates multi-color space information (RGB, HSV, Lab) to construct a 19-dimensional feature vector, comprehensively characterizing molten salt radiation properties. Building upon this foundation, a BO-Transformer-BiLSTM hybrid neural network is designed, achieving high-precision temperature prediction through self-attention mechanisms and bidirectional temporal modeling. Experiments demonstrate that the proposed GMM-Kalman preprocessing reduces the mean absolute error (MAE) from 11.6 degrees C to 1.85 degrees C, representing an approximately 84% performance improvement. The BO-Transformer-BiLSTM model further controls MAE between 0.55 degrees C and 0.60 degrees C, achieves an R2 of 0.96, and attains an RPD of 8.27, with average prediction errors within 2 degrees C. Its overall performance significantly outperforms comparison models. This study provides an effective method for online molten salt temperature prediction in highly disturbed environments and offers a technical reference for visual temperature measurement in similar industrial scenarios.
TiNiZr high-temperature shape memory alloys (SMA), alloyed with niobium and tantalum for the composition Ti 31 Ni 49 Zr 15 Ta 5 and Ti 31 Ni 49 Zr 15 Nb 5 , were aged at different temperatures. In both cases, the hardness increased with the aging temperature and peaks at 700 °C. Martensite structure appears during the aging treatment and grows with aging temperature. The transformation temperature exhibited different trends with the addition of niobium, tantalum, depending on the aging temperatures. With quaternary compositions, aging led to an increase in transformation hysteresis. A key attribute of this trend was the induced lattice strain with the quaternary addition of Ta and Nb, which led to a higher degree of undercooling. Additionally, higher temperature propagated the precipitation of the (Ti, Zr) 2 Ni second phase in the matrix, which peaked for a limited time of 1 hr at 700 °C. The martensite morphology became coarser, indicating a significant grain growth and an overgrowth of the precipitates. The hardness values also peaked at an aging temperature of 700 °C, indicating that a highest volume of precipitation in the matrix.
The determination of the thermal conductivity of slag is important for enhancing thermal efficiency and achieving greater accuracy in numerical simulations. This study focuses on the thermal conductivity of the CaF 2 -CaO-Al 2 O 3 -MgO-TiO 2 slag system, which was determined using the transient hot-wire method. The effects of current intensity, temperature, and slag composition on thermal conductivity were investigated. Summarize the relationship between the thermal conductivity of slag and temperature as well as slag composition changes. The results indicate that, for slags with a porosity in the range 0.33∼0.35, the thermal conductivity of the solid slag (powdered bulk material) increases with temperature, whereas that of the liquid slag decreases with temperature. Furthermore, the thermal conductivity of the slag system increases with increasing CaF 2 content and decreases linearly with increasing of MgO and TiO 2 content. The formation of high thermal conductivity resistance, such as MgO∙Al 2 O 3 and 2MgO∙TiO 2 leads to a decrease in thermal conductivity. According to the above results, the relationship between the thermal conductivity of slag system and the temperature and the composition of slag system is summarized.
Large blast furnaces (design volume ≥ 3,800 m 3 ) underpin India’s primary hot-metal output, yet operator-oriented quantitative assessments for this cohort remain limited. This study analyses FY 2023–24 annual data from twelve Indian large blast furnaces to quantify how routinely controlled thermal and burden variables associate with working-volume productivity (tHM/m 3 /day). Given the small cohort ( n = 12), a parsimonious ordinary least squares (OLS) model is adopted for interpretability and benchmarking. The final six-predictor model—hot-blast temperature (HBT), oxygen enrichment, slag rate, slag basicity (CaO/SiO 2 ), hot-metal silicon, and coke ash—accounts for a large share of cross-plant variation ( R 2 = 97.22%; adjusted R 2 = 93.88%). Higher HBT and oxygen enrichment are positively associated with productivity, whereas higher slag rate, slag basicity, and coke ash show negative associations. Pairwise analyses indicate that higher slag and coke rates co-vary with lower throughput, while gas utilisation (GU) aligns with improved performance and is best interpreted as a diagnostic indicator. Leave-One-Out Cross-Validation (LOOCV) indicates moderate out-of-sample performance (Predicted R 2 = 65.54%), and the model is therefore positioned as an associational benchmarking framework rather than a predictive tool. On a useful-volume basis, benchmarking against published data for large Chinese blast furnaces (2017) indicates that Indian furnaces achieve moderately higher productivity (∼6–7%) but at the cost of higher fuel consumption (∼5–6%) and substantially higher slag generation (∼20–23%). Despite a remaining temporal gap, the comparison provides directional insights, highlighting slag control and fuel efficiency as key improvement areas.
The corrosion behavior of X65 carbon steel under combined CO 2 /H 2 S conditions was investigated at flow velocities of 0, 1.2 and 2.4 m s -1 over 28 days. Electrochemical tests and surface analyses revealed that the corrosion mechanism is governed by a velocity-dependent transition between flow-accelerated corrosion and scale-controlled corrosion. During the first week, increasing flow velocity significantly enhanced mass transfer and reduced the boundary-layer thickness, leading to higher corrosion current densities. Peak i(corr ) values of 120 ± 10, 180 ± 15, and 210 ± 15 μA cm -2 were observed at 0, 500 and 1000 RPM, respectively. In weeks 2–3, the accelerated transport of Fe 2 + away from the surface and of CO 3 2 -/S 2 - toward the steel promoted supersaturation and precipitation of more compact FeCO 3 and FeS 2 scales. By week 4, corrosion rates for all velocities converged to approximately 100 μA cm -2 , indicating a diffusion-controlled regime dominated by the protective scale rather than flow effects. These findings provide mechanistic insight into sour-service flow conditions and offer quantitative guidance for corrosion management in high-velocity pipelines.
This study investigates the corrosion behavior of laser powder bed fusion (produced in simulated soil environments with varying sulfate ion (SO 4 2− ) concentrations. As grounding grids critical components in power systems - face significant corrosion challenges in soil, this research evaluates the innovative application of 3D-printed 2205 DSS. The results demonstrated that increasing SO 4 2− concentration (0 to 1 mol/L) significantly enhanced the corrosion tendency of 2205 DSS, as evidenced by a negative shift in corrosion potential, increased corrosion current density, and reduced polarization resistance. SO 4 2− deteriorated the stability of the passive film, increased oxygen vacancy density, and promoted localized corrosion, thereby accelerating material degradation. Furthermore, the passive film formed in high SO 4 2− environments was thinner and more defective, further compromising corrosion resistance. The findings provide a critical knowledge gap in the field of additive-manufactured corrosion-resistant alloys for power infrastructure applications.
The preparation of metallic samarium through metallothermic reduction is complicated by its variable valence characteristics. This study employed SmF 3 as precursor for magnesium thermal reduction. The reduction products were thoroughly characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) to determine the crystal structure, morphology, elemental distribution, and chemical valence states. Thermodynamic calculations indicate that the reduction of SmF 3 by Mg to form SmF 2 is spontaneous, whereas the formation of metallic Sm is thermodynamically unfavorable. Experimental results demonstrate that at Mg/SmF 3 molar ratios of 0.5, 1.0, and 1.5, the reduction primarily yields Sm 3 F 7 and MgF 2 , while increasing the ratio to 2.0 leads to additional formation of SmMgF 4 . Importantly, varying the Mg/SmF 3 molar ratio does not alter the valence states of samarium in the final products. XPS analysis reveals the coexistence of Sm 3+ and Sm 2+ in all products with a consistent ratio of ∼9:1, where adsorbed oxygen promotes Sm 2+ oxidation. These findings provide important insights for controlling valence states in samarium alloy preparation via metallothermic reduction.
Converter vanadium slag serves as a critical medium in the efficient extraction of vanadium resources, with its viscosity and structural evolution governing the flowability and vanadium enrichment efficiency during the extraction process. This study investigated the CaO-SiO 2 -11.3wt.% V 2 O 5 -13.45wt.% MnO-FeO slag system. The effects of basicity (CaO/SiO 2 ) and FeO content on the viscosity and structure of the slag were examined using the rotating cylinder method, Fourier Transform Infrared Spectroscopy (FTIR), and Raman spectroscopy. The results indicated that as basicity and FeO content increased, both the viscosity and apparent activation energy of the slag decreased substantially, thereby improving fluidity. Notably, the most significant variations in viscosity occurred when the basicity ranged from 0.5 to 1.0 and the FeO content was approximately 31wt.%. FTIR analysis revealed a decrease in the absorption intensity of [SiO 4 ] tetrahedra and a shift toward lower wavenumbers, with the trough depth of the Si-O-Si bond becoming shallower. The central wavenumber shifted from 484.09 cm −1 to 498.64 cm −1 . Raman spectroscopy demonstrated that increases in FeO and CaO promoted the generation of free oxygen ions (O 2− ) and inhibited the transformation of Q 0 and Q 1 species into Q 2 and Q 3 species, consequently reducing the degree of polymerization and complexity of the slag. The most significant modification to the silicate network occurred when the basicity ranged from 0.2 to 0.5 and the FeO content ranged from 23.3% to 31.3%.
Titanium (Ti) alloys are widely used in industrial manufacturing, healthcare, transportation, and other sectors. However, due to significant variations in their physical and chemical properties when welded with other alloys, cracks are likely to develop in the joints, making it difficult to achieve stable welds. Key aspects of these processes include residual stresses, processing windows, temperature, material flow, welding tool wear, and design considerations. Particular emphasis is placed on the relationship between microstructure and resulting properties. This review aims to present current research and applications while providing a comprehensive overview of recent advancements in the welding and joining of titanium and light alloys. Various welding techniques such as fusion welding, brazing, friction welding, and reactive joining have been explored for titanium and light alloys. Among these, friction stir welding (FSW) of titanium alloys is the primary focus of this study, with special attention given to tool design, welding parameters, and weld strength.
