High-frequency induction (HFI) tube welding is an energy-intensive process in which the impeder plays a critical role in power utilization. Conventional ferrite cores often operate near magnetic saturation in small-diameter applications, which can limit efficiency and process stability, particularly under high production rates. Soft magnetic composites (SMCs) offer higher saturation potential, but their internal behavior under welding conditions is difficult to assess experimentally. To address this challenge, this study proposes a methodology for evaluating impeder performance without relying on industrial-scale trials. The approach combines a three-dimensional electromagnetic–thermal model of the welding process with a reduced two-dimensional model for detailed analysis. The predictive capability of the 3D model was assessed through comparison with experimental measurements, providing an initial experimental validation under the investigated operating conditions. Based on this reference, a 2D model is derived by removing the tube and introducing an equivalent correction factor, obtained through comparison with the 3D results, to account for its influence. The reduced model is then used to investigate the internal thermal behavior of a representative SMC (Fluxtrol 50) impeder. The results reveal a pronounced hotspot in the region corresponding to the inductor position, with significantly higher temperatures than in other areas, indicating a critical thermal limitation for operation. The proposed methodology provides a reliable and efficient framework for analyzing and designing impeder systems, offering a practical alternative to costly industrial testing.

Industrial production still relies heavily on thermal processes that predominantly use fossil fuels for energy. This has significant consequences for primary energy use and greenhouse gas emissions. Meanwhile, rapid advances in electrotechnologies—defined as processes that use electrical energy to transform materials through internal heat dissipation (inductive, conductive, or dielectric/microwave) or heat transfer via resistance and infrared systems—are paving the way for a transition to a non-fossil fuel-based energy supply across a wide range of temperatures and power densities. However, replacing fuel with electricity is not simply a case of making a straightforward substitution; the feasibility of this change is determined by process requirements, constraints on installation space and grid connection, the reliability and volatility of the electricity supply, and economics. This paper therefore proposes a simple, decision-oriented methodology to assess the feasibility of defossilisation from energetic and economic perspectives. The methodology centres on a “substitution coefficient” that compares the amount of fossil energy substituted by a given amount of electrical energy and benchmarks this against the primary energy intensity of electricity generation. The methodology is demonstrated using case studies from energy-intensive sectors such as cement production (using resistance and microwave methods), steel strip processing (with inductive boosting combined with resistive holding) and metal melting for cast iron and aluminium. The case studies show under which conditions electrification can be implemented as a drop-in substitute, a hybrid booster or an enabler of new production models. The results indicate where electrotechnologies can deliver primary energy savings and CO2 reductions today and outline the conditions under which their advantages will increase as power systems become more decarbonised.

The phase composition, microstructure and mechanical properties of arc-melted eutectic Nb-18.7Si (at.-%) alloys with different nano-ceramic particle addition (Al2O3, TiC, SiC, 5 mol.-%) were investigated. The results showed that ceramic Al2O3 and TiC nanoparticle are thermally and chemically stable and can be used to tailor phase composition and refine the microstructure, while SiC dissolves completely in the melt. Al2O3 and TiC nano- particle were found mainly in two different areas: (1) at grain boundaries of eutectic structures and (2) on the phase boundaries of silicides inside the eutectics. The presence of the particles refined the microstructure down to nano-scale lamellae by functioning as heterogeneous nuclei for the silicide phase. Without nano particle addition, the Nb-18.7Si alloy was mainly composed of Nb solid solution (Nbss) and Nb3Si. The addition of 5 mol.% Al2O3 promoted the decomposition of the Nb3Si phase and an ultrafine nano-scale lamellar eutectic structure (Nbss + alpha-Nb5Si3) formed. With the addition of 5 mol.-% TiC, primary Nb3Si and coarse Nbss were observed, as well as fine eutectic Nbss + gamma-Nb5Si3 structures. The complete dissolution of SiC led to a hypereutectic alloy with primary Nb3Si and gamma-Nb5Si3 phase, coarse Nbss and eutectic Nbss + gamma-Nb5Si3 structures. The compressive strength was increased from 3068 MPa to 3446 MPa by adding 5 mol.-% Al2O3 due to the formation of the high strength alpha-Nb5Si3 phase, the ultrafine nano-scale lamellar structures of Nbss + alpha-Nb5Si3 and the strong interface of Nbss/ alpha-Nb5Si3. However, the small grain size of the Nbss phase was not effective in inhibiting crack propagation. Crack bridging and branching seem to be important mechanisms at the Nbss phase to inhibit crack propagation. Therefore, the size and distribution of Nbss play a key role. The results indicate that a continuous Nbss phase with embedded silicide phase and coarse Nbss phases can inhibit crack propagation.

Eutectic Nb-18.7Si alloys with different ceramic nanoparticle addition (Al2O3, TiC, SiC, 5 mol.-%), prepared by arc-melting, were heat-treated for 24 h at 1500 degrees C. Phase composition, microstructure transition and mechanical properties were investigated. The results show that the gamma-Nb5Si3 and small Nb3Si phases from the as-cast alloy decomposed into alpha-Nb5Si3 and Nbss/alpha-Nb5Si3-eutectoids. Larger Nb3Si phases still existed after heat treatment. Additionally, after heat treatment the Nbss phases were interconnected to a continuous matrix, while silicides appeared coarsened and spherical while being uniformly distributed in the Nbss phase. This effect was most pronounced in the alloy with addition of Al2O3 nanoparticles, due to the ultrafine nano-scale lamellar structures of Nbss + alpha-Nb5Si3 in its as-cast condition. While the added nanoparticles had a strong effect on the initial microstructure of the as-cast state, they showed no noticeable effects like pinning of grain boundaries during heat treatment. A decrease in hardness was observed due to the coarsening of the microstructure and the reduced area fraction of silicide phases. However, the transformation to the coarser microstructure with a continuous Nbss matrix and spherical silicide phases seems to be effective in inhibiting crack propagation by promoting crack deflection and bridging over the Nbss phase.

Considering Europe’s imperative to reduce CO2 emissions under the Paris Climate Agreement, there is an urgent need to transition to low-CO2 steam generation in industrial processes. Since steam generation is a major contributor to carbon emissions. This paper presents a comparative analysis across various steam generation technologies, including heat pumps, biogas, biomethane, geothermal, and solar thermal solutions. Employing a multidimensional approach, the study assesses key performance indicators such as steam generation cost, CO2 emissions, CO2 abatement costs, and energy demand to unveil viable alternatives to current fossil-based technologies. The findings identify a clear path for transitioning to low-CO2 steam generation within industrial processes, emphasizing the exploration of high-temperature renewable heat sources, followed by electrification and energy carrier substitution approaches. High-temperature renewable heat sources offer the advantage of achieving an 80–90% reduction in CO2 emissions, with the potential for net cost savings at current CO2 pricing. Addressing challenges associated with each steam generation technology is pivotal to finding the perfect fit for each industrial process and ensuring a successful transition to low-CO2 steam generation.

In this paper, three kinds of wall conditions are numerically simulated to investigate deposition, powder recovery and energy aspects of spray dryers. A co-current dryer with a pressure nozzle is chosen as a base dryer and two dryers with fully insulated, and cooled walls are compared with the base one. Governing equations of a transient flow field are solved through the Eulerian approach, while Lagrangian particle tracking predicts particles’ motion. The sticky point curve is employed as a criterion of bouncing or stickiness to model the deposition pattern of skim milk particles on the surfaces. Results show that the spray dryer with cooled walls has better deposition characteristics, while the dryer with insulated surfaces works with higher drying efficiency. Overall, it is observed that the wall conditions can be changed to improve the drying efficiency and wall deposition. However, changing the thermal boundary conditions does not seem to be effective in improving the powder recovery.

This article presents a study of the influence of electromagnetically (EM) forced convection on segregation formation. As a reference case the solidification of Sn-5 wt pct Pb alloy from the Hebditch and Hunt experiment is taken. Applied forcing of convective flow is determined by the dimensionless electromagnetic forcing parameter F. The study was carried out in the range -3.5× 10^6<F<3.5× 10^6. Velocity profiles and flow patterns in the liquid phase are obtained for different applied EM forcing conditions. As a result of parametric analysis, the dependence of the Reynolds number on the electromagnetic forcing parameter was obtained. Electromagnetic forces can significantly affect the flow in the liquid bulk, increasing and slowing down the velocity, as well as changing the circulating flow direction. Solute concentration distribution analysis has shown that EM-forced convection does not affect global solute segregation formation. For the two cases, segregation channels were obtained. However, the analysis of the global segregation index showed that an increase in the Reynolds number provokes a slight decrease in this parameter. The main mechanism of segregation formation is transport of solute rich liquid into the mushy zone. In considered numerical experiment configuration, the penetration into the mushy zone is not large, and even a change in the direction of convection in the liquid bulk does not significantly affect the mushy zone flow. The calculations were made by means of open source code in OpenFOAM and Elmer.

Heat and momentum transfer of low-Prandtl-number fluid (Pr = 0.029) in a closed rectangular cavity (100 × 60 × 10 mm) heated at one side and cooled at the opposite side are analyzed. The electromagnetic forces into the liquid metal are generated by the travelling magnetic field inductor and directed towards buoyancy forces. Large eddy simulations are performed with the Grashof number Gr from 1.9 · 10 to 7.6 · 10 and the electromagnetic forcing parameter F from 2.6 · 10 to 2.6 · 10. An experimental validation of the simulation results of vertical convection and electromagnetically driven flow using GaInSn alloy has been performed. Three types of flow patterns are obtained for different interaction parameters N = F/Gr: counterclockwise flow, clockwise flow, and coexistence of two vortices. Analysis of the Reynolds number shows that the transition zone from natural convection to electromagnetic stirring lies in the range 0.02 < F/Gr < 0.07 and two braking modes are found. The transition point between the convective heat transfer regimes is found for F/Gr around 1. The analysis of isotherms deformation showed that in such convective systems it is possible to achieve minimum deviation of the isotherm shape from a straight line in the range of 0.05 < F/Gr < 0.2.

Electromagnetic stirring (EMS) is nowadays widely applied in continuous casting of metals, in order to increase the quality of the solidified cast. Therefore, an accurate investigation of the stirring effect represents a matter of great interest. Numerical simulations normally calculate only the average Lorentz force distribution inside the molten metal, which plays the major role in the final velocity field generation. Double-frequency component of the force is then neglected, and the real Lorentz force is approximated. In this paper, the stirring effect under the influence of the real Lorentz force distribution is investigated: both average and double-frequency components are calculated, and the resulting flow field inside the melt is analysed. Numerical simulations are experimentally validated with the use of GaInSn melt and UDV probe.

Purpose This paper aims to deal with different induction and conduction heating approaches to realize a tailored heating of round billets for hot forming processes. In particular, this work examines the limits in which tailor-made temperature profiles can be achieved in the billet. In this way, a flow stress distribution based on the temperature field in the material can be set in a targeted manner, which is decisive for forming processes. Design/methodology/approach For the heating of round billets by induction, the rotationally symmetric arrangement is used and a parameterized 2D finite element method model is created. The harmonic electromagnetic solution is coupled with the transient thermal solution. For heating by means of conduction, the same procedure is used only with the use of a 3D model. Findings First results have shown that both methods can achieve very good results for billets with small diameters (d < 30 mm). For larger diameters, an adapted control of the heating process is necessary to ensure through heating of the material. Further investigations are carried out. Practical implications Using tailored heating for forging billets, several forming steps can be achieved in one step. Among other things, higher energy efficiency and throughput rates can be achieved. Originality/value The peculiarity of the tailored heating approach is that, in contrast to inhomogeneous heating, where only partial areas are heated, the entire component is heated to the target.

Electrode Induction Melting Inert Gas Atomization (EIGA) is the state-of-the-art process for the high-quality spherical powder production for additive manufacturing needs. The growing demand for EIGA powders drives the interest for the scale-up of well-established atomization of small Ø50 mm Ti-6Al-4V electrodes, as well as atomization of new refractory materials like Tantalum. However, during first tests with Ø150 mm Ti-6Al-4V and Ø50 mm Tantalum electrodes, the difficulties with melting stability were observed. In order to overcome these difficulties and to improve understanding of details of inductive coupling and favorable melting conditions, a numerical model for the electrode induction melting has been developed and applied.

This paper deals with the numerical simulation and experimental investigation of magnetic flux concentrators (MFC) in particular with innovative additive manufactured MFC for induction heating applications. The novel type of magnetic flux concentrators presented in this paper is based on ferromagne tic particles embedded in ceramic matrix material guaranteeing high temperature mechanical stability and good magnetic performance. The additive manufacturing provides flexible, customized and complex geometry design of the MFC.

Non steady applied magnetic field impact on a liquid metal has good prospects for industry. For a better understanding of heat and mass transfer processes under these circumstances, numerical simulations are needed. A combination of finite elements and volumes methods was used to calculate the flow and solidification of liquid metal under electromagnetic influence. Validation of numerical results was carried out by means of measuring with ultrasound Doppler velocimetry technique, as well as with neutron radiography snapshots of the position and shape of the solid/liquid interface. As a result of the first part of the work, a numerical model of electromagnetic stirring and solidification was developed and validated. This model could be an effective tool for analyzing the electromagnetic stirring during the solidification process. In the second part, the dependences of the velocity pulsation amplitude and the melt velocity maximum value on the magnetic field pulsation frequency are obtained. The ability of the pulsating force to develop higher values of the liquid metal velocity at a frequency close to the MHD resonance was found numerically. The obtained characteristics give a more detailed description of the electrically conductive liquid behaviour under action of pulsating traveling magnetic field.

Electromagnetic control of liquid metal flow has a numerous benefits for modern industry. Alternating magnetic field influence on electro conducting liquids leads to their movement and consequently forced convection. These phenomena are widely used in wide range of metallurgical applications, and one of them is an electromagnetic stirring during the solidification of metal. We consider a case of travelling magnetic field stirrer (TMF) for liquid gallium in a rectangular cell. TMF inductors are used instead of rotating permanent magnets and show-certain advantages, such as a lack of mechanical vibrations and flexible control of magnetic field parameters. The 3D harmonic electromagnetic (EM) analysis is performed by means of finite element method. The magnetic flux density distribution, induced current density and the Lorentz forces in the melt are analyzed. For hydrodynamic simulation of EM driven liquid metal flow finite volume software Fluent was implemented. As a result, a velocity field in liquid metal domain is obtained. Comparison of numerical results with experimental data, obtained by the Doppler ultrasound velocimetry, has a good agreement.

A wide range of industrial metallurgical heating and melting processes are carried out using electrothermal technologies. The application of electrothermal processes offers many advantages from technological, ecological and economical point of view. Although the technology level of the electro heating and melting installations and processes used in the industry today is very high, there are still potentials for improvement and optimization due to the increasing complexity of the applications and the strong requirements regarding the performance and quality of the products but also regarding the reduction of time and costs for the development of new processes and technologies. In this paper recent applications and future development trends for efficient heating and melting by electrothermal technologies in metallurgical processes are described along selected examples like induction heating for forging or rolling of billets, heat treatment of strips and plates, press-hardening processes, induction surface hardening of complex geometries, induction welding as well as induction melting processes.

Comprehensive knowledge of the turbulent flows, heat and mass transfer processes in the melt of induction applications is required to realize efficient metallurgical processes. Therefore, the process oriented development, design and optimization of induction furnaces for melting and casting of metals require praxis oriented simulation and analysis of the complex in-stationary turbulent melt flows and temperature distributions as well as the heat and mass transfer processes in the liquid metal. The studies, presented in this paper, demonstrate the possibilities of using advanced three-dimensional transient numerical modelling for successful simulation of the melt flow as well as heat and mass transfer processes in metallurgical applications. Along selected examples like classical induction crucible furnace and the cold crucible induction furnace for melting and casting of TiAl alloys as well as the innovative electromagnetic levitation melting where the free surface dynamics has to be taken into account the successful development and application of experimentally verified numerical simulation techniques will be demonstrated.

A wide range of industrial metallurgical heating and melting processes are carried out using electrothermal technologies. The application of electrothermal processes offers many advantages from technological, ecological and economical point of view. Although the technology level of the electro heating and melting installations and processes used in the industry today is very high, there are still potentials for improvement and optimization due to the increasing complexity of the applications and the strong requirements regarding the performance and quality of the products but also regarding the reduction of time and costs for the development of new processes and technologies. In this paper recent applications and future development trends for efficient heating and melting by electrothermal technologies in metallurgical processes are described along selected examples like induction heating for forging or rolling of billets, heat treatment of strips and plates, press-hardening processes, induction surface hardening of complex geometries, induction welding as well as induction melting processes.

This paper deals with numerical modeling of longitudinal high-frequency (HF) induction welding of cladded pipes using double frequency approach. Solutions are proposed to reach the required temperature distribution at the welding edge for the cladding composite of S355 and Alloy 625 with single and double frequencies. An advanced consideration of magnetic and other material properties was performed to simulate the dominating physical effects of HF welding. By the use of FEM analysis, the theoretical capability of an inductive longitudinal welding process for cladded pipes has been demonstrated. Despite some simplifications, the dominating effects of the longitudinal welding were considered by the presented model. In the context of the research, a correlation for welding speed, welding frequency and temperature distribution with industrial relevance was found for the cladded pipe welding. Industrial scale process windows for both, single frequency and simultaneous double frequency is presented in this work.