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A multi-strand composite welding wire was applied to join high nitrogen austenitic stainless steel, and microstructures and mechanical properties were investigated. The electrical signals demonstrate that the welding process using a multi-strand composite welding wire is highly stable. The welded joints are composed of columnar austenite and dendritic ferrite and welded joints obtained under high heat input and cooling rate have a noticeable coarse-grained heat-affected zone and larger columnar austenite in weld seam. Compared with welded joints obtained under the high heat input and cooling rate, welded joints have the higher fractions of deformed grains, high angle grain boundaries, Schmid factor, and lower dislocation density under the low heat input and cooling rate, which indicate a lower tensile strength and higher yield strength. The rotated Goss (GRD) (110⟨1 1 ¯ 0⟩) orientation of a thin plate and the cube (C) (001⟨100⟩) orientation of a thick plate are obvious after welding, but the S (123⟨63 4 ¯ ⟩) orientation at 65° sections of Euler’s space is weak. The δ-ferrite was studied based on the primary ferrite solidification mode. It was observed that low heat input and a high cooling rate results in an increase of δ-ferrite, and a high dislocation density was obtained in grain boundaries of δ-ferrite. M23C6 precipitates due to a low cooling rate and heat input in the weld seam and deteriorates the elongation of welded joints. The engineering Stress–strain curves also show the low elongation and tensile strength of welded joints under low heat input and cooling rate, which is mainly caused by the high fraction of δ-ferrite and the precipitation of M23C6.

A high-frequency model of the toroidal powder core inductor with litz wire winding is presented. In the analyzed model, the power losses that occurred in both the winding and the magnetic core were taken into account. A new method of determining the power losses in the winding of a magnetic element made of a litz wire with a circular cross-section, wound on a toroidal magnetic core, for both sinusoidal and deformed currents, by transforming the parameters of the wire to the Dowell equation has been proposed. The methodology of estimating the resistance for the alternating component of the current flowing through a litz wire with a circular cross-section wound on a toroidal core is shown. The influence of the type of winding wire, the shape of the core, the number of winding layers, the winding angle, and the frequency range for which the litz wire obtains lower power losses than a solid-round wire are discussed.

The paper is focused on numerical modeling of multi-strand cable lines placed in free air. Modeling is carried out within the framework of the so-called multi-physics approach using commercial software. The paper describes in detail the steps undertaken to develop realistic, reliable numerical models of power engineering cables, taking into account their geometries and heat exchange conditions. The results might be of interest to the designers of multi-strand cable systems.

In this paper, the effect of ER2209 multi-stranded wire compared to single wire on the microstructure and pitting resistance of 2205 duplex stainless steel submerged arc welded joints was studied using electron backscatter diffraction, scanning electron microscopy, energy spectrum analysis, electrochemistry and other detection techniques. Compared with single-wire welding of duplex stainless steel, the multi-stranded wire deposited more metal and doubled the welding efficiency with the same heat input, while increasing the elemental concentration of Ni in the weld metal and the proportion of austenite in the heat-affected zone. Compared with single-wire welding, multi-stranded wire welding promotes the diffusion of the main alloying elements (Cr, Mo, Ni, N) in the welded joint and improves the mechanical properties and pitting resistance of the welded joint.

In continuous casting, it is common to close single or multiple submerged nozzles of multi-strands tundish to adapt to production rhythm due to insufficient liquid steel or equipment failure. However, the closure of the nozzle will change the flow field in the tundish and further affect the removal efficiency of inclusions in the tundish. For this reason, based on numerical simulation, the flow behavior of liquid steel and the removal of inclusion in tundish with different nozzle closed were studied, and the optimal nozzle closing scheme was obtained, which provided a basis for the selection of nozzle closing in tundish. At the same time, the gas curtain is set in the tundish to alleviate the negative effects such as the increase of dead zone caused by closing nozzle. The results show that the removal rate of inclusions with sizes 10, 30, 50, 70, and 90 μm change from 12.4%, 39.1%, 74.2%, 93.3%, and 95.6% to 14.7%, 36.4%, 76.4%, 85.3%, and 93.8%, respectively. The volume of the tundish dead zone is increased after closure of nozzle, the dead zone of the tundish is improved when the gas is installed, and the dead zone volume was reduced from 14.8% and 16.4% to 13.9 and 14.1%.

The recently developed smart strand can be used to measure the prestress force in the prestressed concrete (PSC) structure from the construction stage to the in-service stage. The higher cost of the smart strand compared to the conventional strand renders it unaffordable to replace all the strands by smart strands, and results in the application of only a limited number of smart strands in the PSC structure. However, the prestress forces developed in the strands of the multi-strand system frequently adopted in PSC structures differ from each other, which means that the prestress force in the multi-strand system cannot be obtained by simple proportional scaling using the measurement of the smart strand. Therefore, this study examines the prestress force distribution in the multi-strand system to find the correlation between the prestress force measured by the smart strand and the prestress force distribution in the multi-strand system. To that goal, the prestress force distribution was measured using electromagnetic sensors for various factors of the multi-strand system adopted on site in the fabrication of actual PSC girders. The results verified the possibility to assume normal distribution for the prestress force distribution per anchor head, and a method computing the mean and standard deviation defining the normal distribution is proposed. This paper presents a meaningful finding by proposing an estimation method of the prestress force based upon field-measured data of the prestress force distribution in the multi-strand system of actual PSC structures.

Prestressed concrete (PSC) bridge resists to deflection and cracking by prestressing its concrete superstructure using steel strands. The initial prestress force introduced in the strands at the completion of the structure influences sensitively its long-term performance. Rating the health of the PSC bridge should thus start with the knowledge of this initial prestress. However, the measurements given by the hydraulic jack and load cell used during prestressing may not be absolute indicators of the effective stress introduced in the strands. Considering that the strain distribution in the anchor can be used to measure the prestress in the strands and that the anchor head is the most accessible part of the PSC member, this study presents a method using the deformation characteristics of the anchor head to evaluate the initial prestress of the strands. To that goal, experimental and numerical analyses were performed on an anchorage-strand system considering the coefficient of friction between the wedge and the anchor head. The results show that the variation of the hoop strain measured in the multi-strand anchor head can be used to evaluate effectively the initial prestress state of the strands with respect to the applied jacking force.

In some substations, shielded wire is made of Copper Clad Aluminum, it can be severely corroded because of the exposing in the air. To reduce the loss, an economy and effective way must be developed. Isolating the shielded wire from moisture and exposing in the air is the best way to protect it. How to replace the corroded wire which is exposing in the air, while the electric cable still working is an important problem to be solved currently. This paper introduces a replacement technology—multi-strand copper wire replacement technology, which can accomplish the replacement work of shielded wire without power outage. This will be a major breakthrough in the power industry.

The Energy Climate Package is the EU response to the Global Warming Challenge.Induction heating processes can contribute to the energy saving goal:20%saving within 2020.European induction manufacturer already propose many efficient solutions at industrial scale.To improve induction devices for an always better energy efficiency,EDF R&D set up a French cooperative project called ISIS with a financial support of the French National Research Agency.Its objective is to promote induction heating as Best Available Technology(BAT)and to develop innovative solutions to increase its efficiency.The ISIS innovations concern the electroheat conversion of induction devices(auto-adaptive multi-coil power supply,low losses coils)and the recovering of fatally lost energy.This paper shows the mid-term results of this project.Firsts control algorithms were successfully tested on a 100 kW 3-coil power supply.A homogenization technique is proposed to model a multi-strand coil.A heat recovery test bench is build and equipped with a PFC control loop to fit with the production fluctuations.

The factors that affect the stability of the melt stream during the casting of wire directly from the melt have been investigated. It is shown that the criticality of process parameters centres mostly on the forces imposed on the melt stream at confluence with the cooling water. The analysis of these forces indicated that the shear component of the disturbance is dependent on the ratio of the velocity of the melt stream (vm) to that of the cooling water (vw) in accord with results obtained from previous experiments. The role of oxide-forming elements in widening the process parameters range is attributed to the increased stability of the melt stream due to the additional shear force resistance offered by the solid oxide layer. The roles of Cr and Si oxides in stabilising the melt stream are confirmed by X-ray photoelectron spectroscopy (XPS) of wire indicating the presence of these oxides on fresh as-cast wires. Melt superheat and nozzle clearance distance are not strictly stream stability factors, but rather their role in glass formation prescribes optimal limits for fully amorphous wire.