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When the conductor is covered with ice on a non-circular section, and there is low-frequency, large-amplitude motion under wind excitation, it is usually called the transmission line galloping phenomenon. Due to the large amplitude, the galloping of the transmission line will lead to line fatigue, increase in tension, damage to hardware, or toppling of towers. In addition, it will also lead to flashover, tripping, and other transmission accidents caused by the short phase distance, which is not conducive to the safe operation of power grids. In order to improve the safety of power grid operation, this paper designed an online monitoring and early warning system for transmission line galloping on the basis of multi-source data and verified the system through implementation. It was found that the safety factor was 1.568, which determines its early warning level and affirms the feasibility of this study. This research has a positive role in improving the safe operation of the power grid.

It is well known in image recognition that global features represent the overall and have the ability to generalize an entire object, while local features can reflect the details, both of which are important for extracting more discriminative features. Recent research has shown that the performance of convolutional neural networks can be improved by introducing an attention module. In this paper, we propose a simple and effective channel attention module named layer feature that meets channel attention module (LC module, LCM), which combines the layer global information with channel dependence to calibrate the correlation between channel features and then adaptively recalibrates channel-wise feature responses. Compared with the traditional channel attention methods, the LC module utilizes the most significant information that needs to be focused on in the overall features to refine the channel relationship. Through empirical studies on CIFAR-10, CIFAR-100, and mini-ImageNet, this work proved its superiority compared to other attention modules in different DCNNs. Furthermore, we performed the two-dimensional visualization of the feature map through the class activation map and intuitively analyzed the effectiveness of the model.

The effect of the current-carrying mold (CCM) current on multi-physics fields and interface bonding quality of compound rolls was studied using ANSYS Parametric Design Language coupling with Fluent to get a reasonable CCM for producing the compound rolls. The results revealed that the magnetic flux density of the slag (Br) was the sum of Bres and Brm, where Bres was generated by the electrode, slag, clad and mandrel current and Brm was generated by the CCM current. When using a single current outlet (SCO) CCM, the axial component (Brmz) generated by the circumferential CCM current and the radial current $$ \left( {\varvec{J}_{\text{r}} } \right) $$ of the slag pool result in an additional rotating Lorentz force. Therefore, irregular circulating flows impacted the uniformity of the temperature field and interfacial bonding quality. By employing four current outlets and a conductive plate (FCO-CP) CCM, circumferential CCM current was reduced, eventually eliminating the Brmz along with rotating Lorentz force. Consequently, the uniformity of the circulating flows, temperature field and interfacial bonding quality was improved. The results of the magnetic flux density (Bz) and circulating flows of simulated results were in good agreement with the corresponding physical experimental results, thus verifying the accuracy of the industrial model. Overall, using FCO-CP CCM could effectively eliminate the deleterious effect of CCM current on multi-physics fields and interface bonding quality, so FCO-CP CCM was reasonable for the production of compound rolls with a uniform bonding quality.

In this study, a comprehensive transient numerical model of electroslag remelting cladding process with dynamic mesh technology is simulated to study the effect of the applied power on the uniformity of melting layer depth along the height of the as-prepared compound roll. The multi-physics fields are solved by the ANSYS Parametric Design Language and Fluent simulation software. The simulation results show that the mandrel absorbs heat (Qmsi) from the slag pool and the melting layer is formed on the mandrel surface. A sufficient metallurgical bonding quality between the mandrel and the clad is confirmed by the close contact of the melting layer with the molten bath of the clad. In addition, the use of high and low power during the early and later stages, respectively, improves the uniformity of the melting layer depth along the height. When high power (235 kW) is applied during the early stage, the height of the compound roll without metallurgical bonding decreases to 52 mm. After the melting layer depth increases to 6 mm along the height, the power decreases to 187 kW. The slag temperature and Qmsi decreases rapidly, and consequently, the melting layer depth initially decreases and then slightly increases along the height. The melting layer depth is acceptable within height of 52 to 260 mm. The change tendency of the melting layer depth along the height of the compound roll obtained by the semi-industrial experiment is in agreement with the simulation results, proving the reliability of the process. Moreover, the results of tensile and Charpy impact tests indicate good metallurgical bonding quality. The process investigated in this paper is expected to be efficient for industrial production of the compound rolls with a uniform melting layer depth.

In the present study, the comprehensive analyses based on the numerical simulation, in situ observation, and metallographic detection were carried out for the roll core of GCr15/45 carbon steel composite roll manufactured by the new electroslag remelting cladding (ESRC) method. During the ESRC process, the temperature distributions at the different radial and longitudinal positions of the roll core have great changes due to the different degrees of heat conduction from the slag bath, as a result, various microstructure and properties were obtained at the different positions of the roll core. The results illustrated that the ESRC process tended to be stable as the composite height reached a certain value and the high-temperature austenitization process mainly occurred in the radial regions where R > 60 mm, whereas no significant changes occurred at the areas where R ≦ 60 mm. The coarse grains and few Widmanstatten structures with proeutectoid ferrite were generated in the roll core areas near the bimetallic interface, while the fine grains with more proeutectoid ferrite were obtained in the roll core area away from the interface. Therefore, a higher tensile strength and a better plasticity were obtained for the specimens away from the interface.

In order to ensure the reliability of transmission line operation, it is necessary to carry out effective monitoring of its motion state, and master the running state of transmission line in real time by means of data analysis and comparison. During this period, transmission line motion state monitoring device is bound to be used. However, in order to ensure the effectiveness of transmission line monitoring, it is necessary to add communication network into the motion state monitoring device, so as to improve the reliability of transmission line data acquisition, transmission and analysis, and ensure the normal and safe operation of transmission circuit.

The operation state of insulators is closely related to the safety and reliability of the power network. Affected by the environment, the insulator strings will gradually age and become low-value or zero-value in insulators. Therefore, it is of great engineering significance to correctly and timely detect whether there are faults in insulators. It has a good engineering application prospect to evaluate the insulation condition of insulators by detecting the surface electric field value of insulators. In this paper, the external axial electric field value of the insulator skirt is obtained through finite element simulation, and the combined neural network model is used. Finally, the effectiveness of the model is verified by the measured data. The experimental results show that this method can effectively identify whether the insulator has deteriorated.

With the upsurge of the digital twin power grid, it is very necessary to carry out a three-dimensional model and simulation analysis of the power grid system. Insulators are one of the important components in the power system, and the appropriate simplification of the simulation model is of great significance. In this paper, the finite element software is used to calculate the three-dimensional model, and the influence of the length of the conductor, the tower, the yoke plate, the grading ring, and the arrangement of the insulators on the axial electric field distribution (EFD) is analyzed. The results show that: the length of the conductor will affect the uniformity of the axial electric field; compared with the grading ring, the yoke plate will cause serious distortion of the electric field intensity curve; the integrity of the tower has different effects; the arrangement of the insulators will affect the magnitude of the electric field and even the shape of the curve. Therefore, in the simulation analysis of the axial electric field, the above factors should be considered when simplifying the insulator model, which will promote the development of relevant digital twin technology.

The austenite decomposition behavior in medium-Mn steel was investigated here by combining thermo-mechanical controlled processing (TMCP) and continuous cooling processes. Microstructures were characterized by means of optical microscopy, electron probe micro analyzer, scanning electron microscopy, electron backscattered diffraction, and transmission electron microscopy. Furthermore, the effect of rolling reduction and cooling path on microstructural evolution and mechanical properties were studied. The results indicated that the austenite region was expanded by manganese, and the ferrite, pearlite, and bainite were not nucleated before martensite transformation even when the cooling rate was decreased to 0.07 °C/min. The approach to tailor yield ratio without compromising tensile strength depends on the control of martensite lath morphology and internal dislocation density. The resistance of lattice to shear transformation increases with the increasing strain hardening of prior austenite, which leads to decrease martensite-start (Ms) temperature. The martensite formed at lower transformation temperatures exhibited relatively high dislocation density and refined laths, resulting in high work-hardening capacity during the early stage of plastic deformation. The crack propagation can be effectively deviated or even terminated by high angle grain boundaries (HAGBs) and the nonparallel structures of martensite packets. These studies on the kinetics and thermodynamics of martensitic transformation confirmed the viability of processing continuously cooled medium-Mn steel in the hot rolling production line.

In the power network system, the main role of transmission tower is responsible for supporting the transmission line, to ensure the normal operation of the power network system. But the transmission tower in the outdoor, easy to be affected by the external environment, resulting in tower collapse, wire broken and other problems. Based on this, this paper, by using multi-sensor data melting technology on transmission tower operation monitoring system are studied, in particular, the system has carried on the design of hardware, software, and then with the inspection of transmission tower temperature and humidity data fusion, the effective monitoring results, confirmed the feasibility of the system design. Through this research, the aim is to make a modest contribution to the transmission tower motion state monitoring.

A novel single-power two-circuit ESR process (ESR-STCCM) with current-carrying mold has been investigated via numerical simulation and experimental research in this paper. A 2D quasi-steady-state mathematical model is developed to describe ESR-STCCM. The electromagnetic field, flow field, slag pool temperature distribution, and the shape of a molten steel pool in ESR-STCCM have been investigated by FLUENT software as well as user-defined functions (UDF). The results indicate that ESR-STCCM is different from the conventional ESR process. The maximum electromagnetic force, current density, Joule heat, and slag pool flow velocity are located in the lower part of the conductor in the ESR-STCCM process. The direction of the maximum electromagnetic force inclines upward. There are two distinct vortices in the slag pool. The larger swirl rotates counterclockwise near the conductor, with a value of 0.0263 m s−1 due to the interaction of the electromagnetic force and gravity. The maximum temperature of the slag pool is 2070 K (1797 °C) and is located in the center of the swirl with a filling ratio of 0.6 and a 20 mm electrode immersion depth. The depth of a molten steel pool is shallower, which is conducive to improving solidification quality. In addition, the filling ratio of 0.6 is conducive to controlling steel solidification quality. Some experiments have been done, and the numerical model is confirmed by experimental results.

We describe here structure-property relationship in a novel 1000 MPa hot-rolled TRIP steel with strain-assisted ferrite processed by thermo-mechanical controlled processing (TMCP) and tuning of the coiling process. A wide range of experimental material characterization techniques, notably, electron microscopy, EBSD, TEM, and nanoindentation were uniquely combined to understand the structure-property relationship. The ultrafine ferrite (average size of ~2.2–3.4 μm) was obtained by strain-assisted ferrite transformation and carbon was enriched in untransformed austenite, which led to increase in the content of retained austenite. The results indicated that ferrite delayed granular bainite transformation, and a high content of ferrite resulted in high austenite hardenability and facilitated the formation of lath bainite and martensite. The volume fraction of retained austenite was initially increased with the decrease of rolling temperature, followed by a decrease. Both granular bainite and lath bainite contained blocky retained austenite, while film-like retained austenite mainly existed in lath bainite. A good combination of strength and plasticity in the experimental steel was obtained because of strong TRIP effect. The product of tensile strength and % elongation (PSE) of the experimental steel approached 20.4 GPa·%, which is significantly greater as compared to hot-rolled ferrite-free TRIP steels.

Experimental and theoretical studies have been carried out to investigate the effects of the slag on desulfurization during the electroslag remelting (ESR) process with a focus of developing a mass transfer model to understand the mechanism of desulfurization. Stainless steel 1Cr21Ni5Ti was used as the electrode and remelted with two different kinds of slags using a 50-kg ESR furnace. The contents of sulfur along the axial direction of product ingots were analyzed. It was found that the sulfur content of 350 ppm in the electrode is reduced to 71 to 95 ppm in the ingot by remelting with the slag containing 5 wt pct of CaO, and lowered more to 47 to 59 ppm with another slag having 20 wt pct CaO. On the basis of the penetration and film theories, the theoretical model developed in this work well elucidates the kinetics of desulfurization revealing the mechanism of sulfur transfer during the ESR process. The calculation results obtained from the model agree well with the experimental results. The model indicates that when sulfur content in electrode is given, there is a corresponding minimum value of sulfur content in the ingot due to the kinetics limit. This lowest sulfur content cannot be further reduced even with increasing L S (sulfur distribution coefficient between metal and slag phases) or decreasing sulfur content in the slag. Constant addition of extra amount of CaO to the molten slag with the increase of sulfur content in the slag during the remelting process can improve the macrosegregation of sulfur distributed along the axial direction of ESR ingots. Since the rate-determining steps of the sulfur mass transfer lie in the metal phase, adding calcium as deoxidizer can change mass transfer of sulfur and thus promote desulfurization further during the ESR process.

Physical simulation of a single-power, two-circuit electroslag remelting (ESR) process with current conductive mold (ESR-STCCM) is carried out in this paper. Wood alloy and sodium chloride solution are used to study the current distribution ratio of passing electrode and conductive part of current carrying mold (conductor). A conventional ESR (CESR) process has been studied as a comparison. The total current of ESR-STCCM is larger than the CESR process, which indicates that the resistance in ESR-STCCM is smaller than in CESR. Results show that the ratio of I electrode/I conductor changes with filling ratio, electrode immersion depth, and effective conductor height. Electrode immersion depth plays an important role on the current distribution ratio. Nevertheless, the effective conductor height has a little influence on the current distribution ratio. A larger filling ratio has an obvious effect on the current distribution ratio in ESR-STCCM. Current flowing through the electrode increases with the increasing of electrode immersion depth under a certain filling ratio. The physical model established can provide an important direction to real ESR-STCCM.

Conventional methods that involve an increase in pressure are used to improve the solubility and yield of Mg in the steelmaking. Under high pressure, the effect of Mg addition on the number, morphological characteristics, composition, size, and density of inclusions in Cr12Mo1V1 steel (C: 1.40–1.60 wt%, Si: ≤0.60 wt%, Mn: ≤0.60 wt%, S: ≤0.03 wt%, P: ≤0.03 wt%, Cr: 11.00–13.00 wt%, V: ≤1.00 wt%, and Mo: 0.70–1.20 wt%) is studied. The experiments are made under three contents of Mg: 0, 0.0012 wt% and 0.0041 wt%. Results show that Al2O3 and MnS inclusions transform into approximately spherical MgO·Al2O3 spinel and spherical MgO·MgS inclusions, respectively. At ~0.07 wt% dissolved aluminum content, the micro content of Mg in molten steel leads to the formation of MgO·Al2O3 spinel inclusions. The MgO·Al2O3 inclusions disappear completely when the mass fraction of Mg is larger than 39.734 × 10−6. Further, as the Mg content increases, the number of inclusions 2 μm decreases. Meanwhile, during molten steel solidification, MnS and MnS–MgS precipitate around MgO·Al2O3 and MgO inclusions, respectively. The densities of MgO·Al2O3 spinel inclusions are lower than those of alumina inclusions. As the Mg content in Mg-containing inclusions increases, the density of inclusions decreases, leading to an improvement in inclusion removal efficiency. The role of Mg in the mechanical properties, tensile fracture morphology, and inclusions of quenched and tempered Cr12Mo1V1 steel is also investigated. As the Mg content increases from 0 wt% to 0.0041 wt%, at the tensile fracture, the area of shear lip goes through a process from small to large, the dimples go through a process from generation to deepening, and the strength and plasticity correspondingly increase.

Electroslag remelting cladding (ESRC) with a t-shape current carrying mold was adopted to make a compound roll including a working layer and mandrel. A comprehensive coupled transient model was established to reveal the basic phenomena of electromagnetic fields, flow fields, temperature fields, and multiphase flow. Meanwhile, the movement of the mandrel and working layer relative to the slag pool was simulated by dynamic mesh technology to reveal the interface bonding mechanism. The mechanism is as follows: The temperature of the mandrel increases and the mandrel melts slightly when the mandrel passes through the slag pool. The fusion layer is a mixture of molten steel of mandrel and working layer that is the connector between the mandrel and the working layer. Therefore, the interface bonding quality is dependent on a fusion layer that is affected by the voltage/power. The investigation indicates that the fusion layer thickness is between 2 and 4 mm in the condition of 40 V that benefits from obtaining a good interface bonding quality.

Many factors influence the chemical composition in electroslag remelting (ESR) steel, including atmosphere in crucible, melting rate, slag composition, deoxidation, and so on. Fluoride-based slag, which is exposed to liquid metal directly, influences the chemical composition of ESR ingots to a large extent. The present paper focuses on the effect of slag on the titanium, silicon, and aluminum contents in ingots based on the interaction of the slag and metal. In present work, superalloy of GH8825 and several slags containing different CaO contents have been employed for investigating the effect of slag on titanium, silicon, and aluminum contents in an electrical resistance furnace under argon atmosphere. Results indicate that the higher CaO content in slag has better capacity for avoiding loss of titanium caused by the reaction of titanium with silica in slag, especially in case of remelting superalloy with high titanium and low silicon content. The CaO has a great effect on the activities of TiO2, SiO2, and Al2O3. Thermodynamic analysis is applied to investigate the CaO behavior. Based on the ion and molecule coexistence theory of slag, activity model is established to calculate the activities of components containing titanium, silicon, and aluminum elements in a six-component slag consisting of CaO-CaF2-Al2O3-SiO2-TiO2-MgO. The components containing titanium, silicon, and aluminum in slag are mainly CaO·TiO2, 2CaO·SiO2, CaO·SiO2, CaO·Al2O3, and MgO·Al2O3. With the increase of CaO mass fraction in slag, the activity coefficient of SiO2 decreases significantly, whereas slightly change happens for Al2O3. As a result, the \( \lg ({{\gamma_{{{\text{SiO}}_{2} }} } \mathord{\left/ {\vphantom {{\gamma_{{{\text{SiO}}_{2} }} } {\gamma_{{{\text{TiO}}_{2} }} }}} \right. \kern-0pt} {\gamma_{{{\text{TiO}}_{2} }} }}) \) decreases with increasing CaO content, which is better for preventing loss of titanium caused by the reaction of titanium with silica in slag. The slag with high CaO and appropriate TiO2 content is suitable for electroslag remelting of GH8825.

Droplet formation and departure from an electrode tip affect the temperature distribution in liquid slag and a molten steel pool, as well as the removal of nonmetallic inclusions in the electroslag remelting process. In this article, magneto-hydrodynamics modules coupled with a volume of fluid (VOF) model (as described in VOF model theory) for tracking phase distribution have been employed to develop the electrode fusion model and to investigate formation and departure of a droplet from the electrode tip. Subsequently, the remelting rate and molten steel pool have been achieved based on the electrode fusion model. Results indicate that a droplet can increase the flow rate of liquid slag, especially the region of droplet fall through the slag pool; yet it has little impact on the flow distribution. Asymmetric flow can take place in a slag pool due to the action of the droplet. The depth of the molten steel pool increases in the presence of droplets, but the width of the mushy zone decreases. In addition, the shape of the electrode tip is not constant but changes with its fusion. The remelting rate is calculated instead of being imposed in this work. The development of the model supports further understanding of the process and the ability to set the appropriate operating parameters, especially for expensive and easy segregation materials.

The electroslag casting with liquid metal (ESC LM) is a new technology for producing composite roll of high quality based on electroslag metallurgy. In the present work, a two-dimensional quasi-steady state mathematical model of just one half of the ESC LM facility is developed due to the axial symmetry. Influences of operating voltage and pouring temperature on the heat transfer of the composite roll system have been studied. The Lorentz forces and Joule heat are combined with the turbulent flow and energy equations via additional source terms in these equations by the user-defined functions (UDF) based on Fluent software. Simulation results indicate that the distributions of electric potential, current density, Lorentz forces, and Joule heat are concentrated on the upper area of slag bath and a much shallower molten steel pool is obtained. By using the current carrying mold, the heat transfer from slag bath and superheat of the molten steel pool are lower than the conventional ESR process, which is beneficial to a vertical crystallization and an excellent bonding interface between the roll core and working layer of the composite roll. The study of this paper gives us a better understanding of the ESC LM process.

A novel process involving thermo-mechanical controlled processing (TMCP) and coiling process was adopted to obtain multiple-phase mixed microstructure. The coiling temperature governed microstructural evolution, stability of retained austenite (RA) and microstructure-properties relationships. The results indicated that the optimum properties were obtained at a coiling temperature of 485 °C with combination of tensile strength of 1006 MPa, elongation of 13.3%, hole-expansion ratio of 28% and impact toughness of 14.7 J (1/4-Charpy size sample at −20 °C). A small amount of RA was present when the coiling temperature was 430 °C (close to the Ms point), resulting in low elongation. The size of blocky RA located at grain boundary was ~450 nm, whereas, the film-like RA embedded in bainite laths was ~40–110 nm. The film-like RA was more stable than blocky RA, which enabled superior formability. Both types of RA provided positive and continuous TRIP effect during deformation. But the presence of a large amount of high-carbon martensite adversely affected impact toughness and formability because it acted as a source for crack initiation as a hard phase in the matrix.

Surface tensions of slag addition MgO and SiO2 based on conventional 70%CaF2-30%Al2O3 and 60%CaF2-20%CaO-20%Al2O3 (mass fraction) at 1300 °C, 1400 °C and 1500 °C were investigated. Influence mechanism of MgO and SiO2 on slag surface tension was also analyzed. Results indicate that surface tension decreases with the increase of MgO content in the case of the MgO content (mass fraction) less than 8%, however, when MgO content (mass fraction) is from 8% to 30%, surface tension increases with the increase of MgO content. When SiO2 content (mass fraction) is from 2% to 8%, surface tension decreases with the increase of SiO2 content. Additionally, the relationship between surface tension and optical basicity is a monotonically increasing linear function. Research findings can provide important reference for slag design and the study of slag-metal interfacial tension.

Many factors influence the non-metallic inclusions in electroslag steel including furnace atmosphere and inclusions’ content in the consumable electrode, slag amount and its composition, power input, melting rate, filling ratio, and so on. Fluoride containing slag, which influences the non-metallic inclusions to a great extent, has been widely used for the electroslag remelting process. The current paper focuses on the effect of fluoride containing slag on the inclusions in electroslag ingots based on the interaction of the slag-metal interface and electroslag remelting process. In this work, die steel of CR-5A and several slags have been employed for investigating the effect of slag on inclusions in an electrical resistance furnace under argon atmosphere in order to eliminate the effect of ambient oxygen. Specimens were taken at different times for analyzing the content, dimensions, and type of non-metallic inclusions. Results of quantitative metallographic analysis indicate that a multi-component slag has better capacity for controlling the amount of inclusions; especially protective gas atmosphere has also been adopted. The findings of inclusions in electroslag steel by SEM–EDS analysis reveal that most non-metallic inclusions in electroslag steel are MgO-Al2O3 inclusions for multi-component slags, but it is Al2O3 inclusions when remelting using conventional 70 wt pct CaF2-30 wt pct Al2O3 slag. The maximal inclusions’ size using multi-component slags is less than that using conventional binary slag. Small filling ratio as well as protective gas atmosphere is favorable for controlling the non-metallic inclusions in electroslag steel. All the results obtained will be compared to the original state inclusions in steel, which contribute to choice of slag for electroslag remelting.